Systematic significance of midrib vascular bundles in some Schefflera Spreng (Araliaceae) species

NASA Astrophysics Data System (ADS)

Noor-Syaheera, M. Y.; Noraini, T.; Aida-Shafreena, A. P.

2014-09-01

Anatomy study was undertaken on midrib vascular bundles of six Schefflera Spreng species, namely as S. obovatilimba, S. borneensis, S.kinabaluensis, S.lineamentorum, S. opacus and S.petiolosa. The genus Schefflera belongs to the family Araliaceae. The objective of this study is to determine variations in the midrib anatomical characteristics that can be used to identify species. Leaves samples were collected from various forest reserves in Sabah and Sarawak, Malaysia., were fixed in AA (Acetic acid: Alcohol, in a ratio of 1:3), the midrib parts then were sectioned using sliding microtome, were stained in Safranin and Alcian blue, been mounted in Eupharal and were observed under light microscope. Findings in this study have shown that all species have complex structure of vascular bundles. Each species has identical arrangement of vascular bundles and can be very useful for species identification. As a conclusion, variation in the midrib anatomical characteristics is outstanding and can has taxonomic value in the genus Schefflera respectively.

Additional Amphivasal Bundles in Pedicel Pith Exacerbate Central Fruit Dominance and Induce Self-Thinning of Lateral Fruitlets in Apple1[C][W

PubMed Central

Celton, Jean-Marc; Dheilly, Emmanuelle; Guillou, Marie-Charlotte; Simonneau, Fabienne; Juchaux, Marjorie; Costes, Evelyne; Laurens, François; Renou, Jean-Pierre

2014-01-01

Apple (Malus × domestica) trees naturally produce an excess of fruitlets that negatively affect the commercial value of fruits brought to maturity and impact their capacity to develop flower buds the following season. Therefore, chemical thinning has become an important cultural practice, allowing the selective removal of unwanted fruitlets. As the public pressure to limit the use of chemical agents increases, the control of thinning becomes a major issue. Here, we characterized the self-thinning capacity of an apple hybrid genotype from the tree scale to the molecular level. Additional amphivasal vascular bundles were identified in the pith of pedicels supporting the fruitlets with the lowest abscission potential (central fruitlet), indicating that these bundles might have a role in the acquisition of dominance over lateral fruitlets. Sugar content analysis revealed that central fruitlets were better supplied in sorbitol than lateral fruitlets. Transcriptomic profiles allowed us to identify genes potentially involved in the overproduction of vascular tissues in central pedicels. In addition, histological and transcriptomic data permitted a detailed characterization of abscission zone development and the identification of key genes involved in this process. Our data confirm the major role of ethylene, auxin, and cell wall-remodeling enzymes in abscission zone formation. The shedding process in this hybrid appears to be triggered by a naturally exacerbated dominance of central fruitlets over lateral ones, brought about by an increased supply of sugars, possibly through additional amphivasal vascular bundles. The characterization of this genotype opens new perspectives for the selection of elite apple cultivars. PMID:24550240

Causes and Effects of Changes in Xylem Functionality in Apple Fruit

PubMed Central

DRAŽETA, LAZAR; LANG, ALEXANDER; HALL, ALISTAIR J.; VOLZ, RICHARD K.; JAMESON, PAULA E.

2004-01-01

• Background and Aims The xylem in fruit of a number of species becomes dysfunctional as the fruit develops, resulting in a reduction of xylem inflow to the fruit. Such a reduction may have consequential effects on the mineral balance of the fruit. The aim of this study was to elucidate the dynamics and nature of xylem failure in developing apples (Malus domestica) showing differing susceptibilities to bitter pit, a calcium‐related disorder. • Methods Developmental changes in xylem functionality of the fruit were investigated in ‘Braeburn’ and ‘Granny Smith’ apples by using a dye infusion technique, to stain the vasculature along the path of dye movement. The vascular bundles were clearly visible in transverse section when fruit were sectioned equatorially. The intensity of staining of the vascular bundles in the fruit was recorded at regular intervals throughout the season. Tissue containing dysfunctional bundles was fixed and embedded in wax for subsequent sectioning and examination. • Key Results As the season progressed, an increasing proportion of vascular bundles failed to show any staining, with the most marked change occurring in the primary bundles, and in nearly all bundles with increasing distance from the stalk end of the fruit. Decreased conductance in the primary bundles of ‘Braeburn’ occurred earlier than in ‘Granny Smith’. Microscopy revealed that the xylem in vascular bundles of the fruit suffered substantial damage, indicating that the mode of dysfunction was via the physical disruption of the xylem caused by expansion of the flesh. • Conclusions Results support the view that the relative calcium deficiency of apple fruit is due to a progressive breakdown of xylem conductance caused by growth‐induced damage to the xylem strand in the bundle. The earlier onset of xylem dysfunction in the cultivar more susceptible to bitter pit suggests that the relative growth dynamics of the fruit may control the occurrence of calcium‐related disorders. PMID:14988096

Influence of calcium oxalate crystal accumulation on the calcium content of seeds from Medicago truncatula

USDA-ARS?s Scientific Manuscript database

Crystals of calcium oxalate often form in cells adjacent to the vascular bundles in the tissues along the xylem stream. This spatial crystal pattern suggests a role for calcium oxalate formation in regulating calcium transport and partitioning to edible organs such as seeds. To investigate this pote...

Vascular leiomyoma of the oral cavity. Clinical, histopathological and immunohistochemical characteristics. Presentation of five cases and review of the literature.

PubMed

Gaitan Cepeda, Luis Alberto; Quezada Rivera, Daniel; Tenorio Rocha, Fernando; Leyva Huerta, Elba Rosa; Mendez Sánchez, Edgar Ramiro

2008-08-01

Leiomyoma, a benign neoplasia arising from smooth muscle is an uncommon neoplasia of the oral cavity. The most common histological subtype in the oral cavity is the vascular one. To supplement information on vascular leiomyoma of the oral cavity (VLOC), we present cases of VLOC describing their clinical, histological, and immunohistochemical characteristics. Case reports. Five cases of VLOC (3 females; 2 males) from the Clinical and Experimental Pathology Laboratory, Dental School, National Autonomous University of México, are included. The most frequent clinical characteristic of VLOC was a single, asymptomatic, slow growing nodule. The age average of the cases was 40.6, however 3 out of our 5 cases were < or = 40 years old at the moment of their diagnosis. The lesions were composed of fusiform cells arranged in bundles or fascicles. The neoplastic cells were characterized by eosinophilic cytoplasm and tapered nuclei. The presence of vascular spaces was prominent in all cases. The immunocharacteristics of VLOC neoplastic cells were: alpha smooth muscle (+); vimentin (+), desmin (+), CD34 (-) and S-100 protein (-). The endothelial cells of vascular spaces were CD34 (+). Differential diagnosis of VLOC with fusocellular neoplasm is discussed.

Specialised sympathetic neuroeffector associations in rat iris arterioles

PubMed Central

SANDOW, SHAUN L.; WHITEHOUSE, DREW; HILL, CARYL E.

1998-01-01

Vascular sympathetic neuroeffector associations have been examined in rat iris arterioles using serial section electron microscopy and reconstruction techniques. Examination of random sections showed that, of all profiles of varicosities (199) seen to lie closer than 4 μm to vascular smooth muscle cells, only a small proportion (29/199) were found in close association with vascular smooth muscle cells, where adjacent membranes were separated by less than 100 nm. However, serial section examination, from intervaricose region to intervaricose region, of 79 varicosities similarly observed lying within 4 μm of vascular smooth muscle cells showed that 54 formed close associations with vascular smooth muscle cells. In serial sections, all these varicosities were also closely associated with melanocytes and of the 25 remaining varicosities, 22 formed close associations with melanocytes alone, whilst 3 did not come into close association with any effector cell. The increased observation of close associations with vascular smooth muscle cells in serial sections, compared with random sections, is consistent with the demonstration that the area of contact only occupies, on average, a small percentage (5%) of the total surface area of the varicosity as seen in the 3-dimensional reconstructions. In both random and serial sections, close associations were observed between varicosities and vascular smooth muscle cells or melanocytes irrespective of whether fibres were present singly or in small nerve bundles. Three-dimensional reconstruction of associations of varicosities and vascular smooth muscle cells demonstrated several common features, such as accumulations of synaptic vesicles and loss of Schwann cell covering at the region of membrane facing the effector cell. The similarity in the appearance of the neuroeffector association seen in this study and those described in previous studies provides evidence for the existence of a common sympathetic neuroeffector association, irrespective of the receptor subtype involved in neurotransmission. PMID:9568560

Cellular sequestration of cadmium in the hyperaccumulator plant species Sedum alfredii.

PubMed

Tian, Shengke; Lu, Lingli; Labavitch, John; Yang, Xiaoe; He, Zhenli; Hu, Hening; Sarangi, Ritimukta; Newville, Matt; Commisso, Joel; Brown, Patrick

2011-12-01

Spatial imaging of cadmium (Cd) in the hyperaccumulator Sedum alfredii was investigated in vivo by laser ablation inductively coupled plasma mass spectrometry and x-ray microfluorescence imaging. Preferential Cd accumulation in the pith and cortex was observed in stems of the Cd hyperaccumulating ecotype (HE), whereas Cd was restricted to the vascular bundles in its contrasting nonhyperaccumulating ecotype. Cd concentrations of up to 15,000 μg g(-1) were measured in the pith cells, which was many fold higher than the concentrations in the stem epidermis and vascular bundles in the HE plants. In the leaves of the HE, Cd was mainly localized to the mesophyll and vascular cells rather than the epidermis. The distribution pattern of Cd in both stems and leaves of the HE was very similar to calcium but not zinc, irrespective of Cd exposure levels. Extended x-ray absorption fine structure spectroscopy analysis showed that Cd in the stems and leaves of the HE was mainly associated with oxygen ligands, and a larger proportion (about 70% in leaves and 47% in stems) of Cd was bound with malic acid, which was the major organic acid in the shoots of the plants. These results indicate that a majority of Cd in HE accumulates in the parenchyma cells, especially in stems, and is likely associated with calcium pathways and bound with organic acid (malate), which is indicative of a critical role of vacuolar sequestration of Cd in the HE S. alfredii.

Immunolocalization of antioxidant enzymes in high-pressure frozen root and stem nodules of Sesbania rostrata.

PubMed

Rubio, Maria C; Becana, Manuel; Kanematsu, Sumio; Ushimaru, Takashi; James, Euan K

2009-01-01

The activities and localizations of superoxide dismutases (SODs) were compared in root and stem nodules of the semi-aquatic legume Sesbania rostrata using gel-activity assays and immunogold labelling, respectively. Nodules were fixed by high-pressure freezing and dehydrated by freeze substitution. Stem nodules showed more total and specific SOD activities than root nodules because of the presence of chloroplastic CuZnSOD. Most of the total SOD activity of stem and root nodules resulted from 'cytosolic' CuZnSOD, localized in the cytoplasm and chromatin, and from MnSOD in the bacteroids and in the mitochondria of vascular tissue. FeSOD was present in nodule plastids and in leaf chloroplasts, and was found to be associated with chromatin. Superoxide production was detected histochemically in the vascular bundles and in the infected tissue of stem and root nodules, whereas peroxide accumulation was observed in the cortical cell walls and intercellular spaces, as well as within the infection threads of both nodule types. These data suggest a role of CuZnSOD and FeSOD in protecting nuclear DNA from reactive oxygen species and/or in modulating gene activity. The enhanced levels of CuZnSOD, MnSOD and superoxide production in vascular bundle cells are consistent with a role of CuZnSOD and superoxide in the lignification of xylem vessels, but also suggest additional functions in coping with superoxide production by the high respiratory activity of parenchyma cells.

Fruit weight is controlled by Cell Size Regulator encoding a novel protein that is expressed in maturing tomato fruits

PubMed Central

Chakrabarti, Manohar; Liu, Xiaoxi; Wang, Yanping; Ramos, Alexis

2017-01-01

Increases in fruit weight of cultivated vegetables and fruits accompanied the domestication of these crops. Here we report on the positional cloning of a quantitative trait locus (QTL) controlling fruit weight in tomato. The derived allele of Cell Size Regulator (CSR-D) increases fruit weight predominantly through enlargement of the pericarp areas. The expanded pericarp tissues result from increased mesocarp cell size and not from increased number of cell layers. The effect of CSR on fruit weight and cell size is found across different genetic backgrounds implying a consistent impact of the locus on the trait. In fruits, CSR expression is undetectable early in development from floral meristems to the rapid cell proliferation stage after anthesis. Expression is low but detectable in growing fruit tissues and in or around vascular bundles coinciding with the cell enlargement stage of the fruit maturation process. CSR encodes an uncharacterized protein whose clade has expanded in the Solanaceae family. The mutant allele is predicted to encode a shorter protein due to a 1.4 kb deletion resulting in a 194 amino-acid truncation. Co-expression analyses and GO term enrichment analyses suggest association of CSR with cell differentiation in fruit tissues and vascular bundles. The derived allele arose in Solanum lycopersicum var cerasiforme and appears completely fixed in many cultivated tomato’s market classes. This finding suggests that the selection of this allele was critical to the full domestication of tomato from its intermediate ancestors. PMID:28817560

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tatsumi, Y.; Chachin, K.; Ogata, K.

The purpose of the experiment was to determine the changes of o- diphenol, ascorbic acid, and activities of polyphenol oxidase and peroxidase, accompanied with the browning by the low dose of gamma ray, in three parts of tuber tissue (cortex, vascular bundle, and pith), and to observe the relation between the browning and the changes of ihose compounds and enzyme activities. The odiphenol content increased in irradiated tabers and the increasing rate was greater in cortex and vascular bundle than in pith. The ascorbic acid content decreased with higher doses, and the decreasing rate was greater in cortex and vascularmore » bundle than in pith. The activities of polyphenol oxidase and peroxidase also increased in irradiated tubers. The activity of polyphenol oxidase increased more in cortex than in vascular bundle and pith and the activity of peroxidase increased more in vascular bundle than in cortex and pith. ln the potato tubers in which irradiation was conducted immediately after harvest, the browning was induced within several days after irradiation. However, in the potato tubers in which irradiation was conducted about 3 months, the browning did not occur after irradiation. The former showed the increase of o-diphenol content and the activities of these enzymes, and the decrease of ascorbic acid content, the latter did not show the changes of o-diphenol and ascorbic acid and activities of the enzymes. (auth)« less

Photosynthesis-related characteristics of the midrib and the interveinal lamina in leaves of the C3–CAM intermediate plant Mesembryanthemum crystallinum

PubMed Central

Kuźniak, Elżbieta; Kornas, Andrzej; Kaźmierczak, Andrzej; Rozpądek, Piotr; Nosek, Michał; Kocurek, Maciej; Zellnig, Günther; Müller, Maria; Miszalski, Zbigniew

2016-01-01

Background and Aims Leaf veins are usually encircled by specialized bundle sheath cells. In C4 plants, they play an important role in CO2 assimilation, and the photosynthetic activity is compartmentalized between the mesophyll and the bundle sheath. In C3 and CAM (Crassulacean acid metabolism) plants, the photosynthetic activity is generally attributed to the leaf mesophyll cells, and the vascular parenchymal cells are rarely considered for their role in photosynthesis. Recent studies demonstrate that enzymes required for C4 photosynthesis are also active in the veins of C3 plants, and their vascular system contains photosynthetically competent parenchyma cells. However, our understanding of photosynthesis in veins of C3 and CAM plants still remains insufficient. Here spatial analysis of photosynthesis-related properties were applied to the midrib and the interveinal lamina cells in leaves of Mesembryanthemum crystallinum, a C3–CAM intermediate plant. Methods The midrib anatomy as well as chloroplast structure and chlorophyll fluorescence, diurnal gas exchange profiles, the immunoblot patterns of PEPC (phosphoenolpyruvate carboxylase) and RubisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase), H2O2 localization and antioxidant enzyme activities were compared in the midrib and in the interveinal mesophyll cells in leaves of C3 and CAM plants. Key Results Leaf midribs were structurally competent to perform photosynthesis in C3 and CAM plants. The midrib chloroplasts resembled those in the bundle sheath cells of C4 plants and were characterized by limited photosynthetic activity. Conclusions The metabolic roles of midrib chloroplasts differ in C3 and CAM plants. It is suggested that in leaves of C3 plants the midrib chloroplasts could be involved in the supply of CO2 for carboxylation, and in CAM plants they could provide malate to different metabolic processes and mediate H2O2 signalling. PMID:27091507

Photosynthesis-related characteristics of the midrib and the interveinal lamina in leaves of the C3-CAM intermediate plant Mesembryanthemum crystallinum.

PubMed

Kuźniak, Elżbieta; Kornas, Andrzej; Kaźmierczak, Andrzej; Rozpądek, Piotr; Nosek, Michał; Kocurek, Maciej; Zellnig, Günther; Müller, Maria; Miszalski, Zbigniew

2016-06-01

Leaf veins are usually encircled by specialized bundle sheath cells. In C4 plants, they play an important role in CO2 assimilation, and the photosynthetic activity is compartmentalized between the mesophyll and the bundle sheath. In C3 and CAM (Crassulacean acid metabolism) plants, the photosynthetic activity is generally attributed to the leaf mesophyll cells, and the vascular parenchymal cells are rarely considered for their role in photosynthesis. Recent studies demonstrate that enzymes required for C4 photosynthesis are also active in the veins of C3 plants, and their vascular system contains photosynthetically competent parenchyma cells. However, our understanding of photosynthesis in veins of C3 and CAM plants still remains insufficient. Here spatial analysis of photosynthesis-related properties were applied to the midrib and the interveinal lamina cells in leaves of Mesembryanthemum crystallinum, a C3-CAM intermediate plant. The midrib anatomy as well as chloroplast structure and chlorophyll fluorescence, diurnal gas exchange profiles, the immunoblot patterns of PEPC (phosphoenolpyruvate carboxylase) and RubisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase), H2O2 localization and antioxidant enzyme activities were compared in the midrib and in the interveinal mesophyll cells in leaves of C3 and CAM plants. Leaf midribs were structurally competent to perform photosynthesis in C3 and CAM plants. The midrib chloroplasts resembled those in the bundle sheath cells of C4 plants and were characterized by limited photosynthetic activity. The metabolic roles of midrib chloroplasts differ in C3 and CAM plants. It is suggested that in leaves of C3 plants the midrib chloroplasts could be involved in the supply of CO2 for carboxylation, and in CAM plants they could provide malate to different metabolic processes and mediate H2O2 signalling. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Sucrose-Metabolizing Enzymes in Transport Tissues and Adjacent Sink Structures in Developing Citrus Fruit 1

PubMed Central

Lowell, Cadance A.; Tomlinson, Patricia T.; Koch, Karen E.

1989-01-01

Juice tissues of citrus lack phloem; therefore, photosynthates enroute to juice sacs exit the vascular system on the surface of each segment. Areas of extensive phloem unloading and transport (vascular bundles + segment epidermis) can thus be separated from those of assimilate storage (juice sacs) and adjacent tissues where both processes occur (peel). Sugar composition, dry weight accumulation, and activities of four sucrose-metabolizing enzymes (soluble and cell-wall-bound acid invertase, alkaline invertase, sucrose synthase, and sucrose phosphate synthase) were measured in these transport and sink tissues of grapefruit (Citrus paradisi Macf.) to determine more clearly whether a given enzyme appeared to be more directly associated with assimilate transport versus deposition or utilization. Results were compared at three developmental stages. Activity of sucrose (per gram fresh weight and per milligram protein) extracted from zones of extensive phloem unloading and transport was significantly greater than from adjacent sink tissues during the stages (II and III) when juice sacs grow most rapidly. In stage II fruit, activity of sucrose synthase also significantly surpassed that of all other sucrose-metabolizing enzymes in extracts from the transport tissues (vascular bundles + segment epidermis). In contrast, sucrose phosphate synthase and alkaline invertase at this stage of growth were the most active enzymes from adjacent, rapidly growing, phloem-free sink tissues (juice sacs). Activity of these two enzymes in extracts from juice sacs was significantly greater than that form the transport tissues (vascular bundles + segment epidermis). Soluble acid invertase was the most active enzyme in extracts from all tissues of very young fruit (stage I), including nonvascular regions, but nearly disappeared prior to the onset of juice sac sugar accumulation. The physiological function of high sucrose synthase activity in the transport tissues during rapid sucrose import remains to be determined. PMID:16666942

Phloem unloading follows an extensive apoplasmic pathway in cucumber (Cucumis sativus L.) fruit from anthesis to marketable maturing stage.

PubMed

Hu, Liping; Sun, Huihui; Li, Ruifu; Zhang, Lingyun; Wang, Shaohui; Sui, Xiaolei; Zhang, Zhenxian

2011-11-01

The phloem unloading pathway remains unclear in fruits of Cucurbitaceae, a classical stachyose-transporting species with bicollateral phloem. Using a combination of electron microscopy, transport of phloem-mobile symplasmic tracer carboxyfluorescein, assays of acid invertase and sucrose transporter, and [(14)C]sugar uptake, the phloem unloading pathway was studied in cucumber (Cucumis sativus) fruit from anthesis to the marketable maturing stage. Structural investigations showed that the sieve element-companion cell (SE-CC) complex of the vascular bundles feeding fruit flesh is apparently symplasmically restricted. Imaging of carboxyfluorescein unloading showed that the dye remained confined to the phloem strands of the vascular bundles in the whole fruit throughout the stages examined. A 37 kDa acid invertase was located predominantly in the cell walls of SE-CC complexes and parenchyma cells. Studies of [(14)C]sugar uptake suggested that energy-driven transporters may be functional in sugar trans-membrane transport within symplasmically restricted SE-CC complex, which was further confirmed by the existence of a functional plasma membrane sucrose transporter (CsSUT4) in cucumber fruit. These data provide a clear evidence for an apoplasmic phloem unloading pathway in cucumber fruit. A presumption that putative raffinose or stachyose transporters may be involved in soluble sugars unloading was discussed. © 2011 Blackwell Publishing Ltd.

The phylogenetic significance of the carpophore in Apiaceae

PubMed Central

Liu, Mei; Plunkett, Gregory M.; Van Wyk, Ben-Erik; Tilney, Patricia M.; Lowry, Porter P.

2012-01-01

Background and aims Fruit structural characters have traditionally been important in the taxonomy of the family Apiaceae. Previous investigations using a limited number of taxa have shown that the carpophore may be especially useful in helping to circumscribe subfamily Azorelloideae. The present study examines, for the first time, carpophore structure in 92 species from 43 genera, representing all subfamilies of Apiaceae, and including all genera assigned to subfamily Azorelloideae. Phylogenetic interpretations are made for the first time, using all available information, and a standard terminology is proposed to describe the various character states found in carpophores. Methods Carpophore structure was studied in detail using light microscopy. Key Results Carpophores, when present, may be categorized into two main groups (B and C) based mainly on the arrangement of the vascular bundles in transverse section, and further divided into six sub-types according to the length of the carpophore (short in B1 and C1) and whether they are entire (B1–B3 and C1) or bifurcate (B4 and C2). Free carpophores are absent in subfamily Mackinlayoideae, and in tribes Lichtensteinieae and Phlyctidocarpeae, which have two opposite vascular bundles (Group A). Entire carpophores with one or two vascular bundles, or bifurcate carpophores with lateral vascular bundles (arranged side by side within the commissural plane), are the main types characterizing Azorelloideae. The short, hygroscopic carpophores found in Choritaenia are unique in Apiaceae and provide additional evidence for the exclusion of this genus from Azorelloideae. Carpophore type C2 is typical for most Apioideae sensu lato (exceptions are, for example, Arctopus and Alepidea, which have type B2). Conclusions A single carpophore and ventral vascular bundles not forming free carpophores are proposed to be the ancestral conditions in Apiaceae, while bifurcate carpophores with opposite vascular bundles are the derived state, present in most Apioideae. Secondary reductions seem to have occurred in several unrelated lineages in all major groups, e.g. many Azorelloideae, several protoapioids (including nearly all members of the tribe Saniculeae) and 29 euapioid genera (e.g. some Oenantheae). PMID:22966116

Sites of action of elevated CO2 on leaf development in rice: discrimination between the effects of elevated CO2 and nitrogen deficiency.

PubMed

Tsutsumi, Koichi; Konno, Masae; Miyazawa, Shin-Ichi; Miyao, Mitsue

2014-02-01

Elevated CO2 concentrations (eCO2) trigger various plant responses. Despite intensive studies of these responses, the underlying mechanisms remain obscure. In this work, we investigated when and how leaf physiology and anatomy are affected by eCO2 in rice plants. We analyzed the most recently fully expanded leaves that developed successively after transfer of the plant to eCO2. To discriminate between the effects of eCO2 and those of nitrogen deficiency, we used three different levels of N application. We found that a decline in the leaf soluble protein content (on a leaf area basis) at eCO2 was only observed under N deficiency. The length and width of the leaf blade were reduced by both eCO2 and N deficiency, whereas the blade thickness was increased by eCO2 but was not affected by N deficiency. The change in length by eCO2 became detectable in the secondly fully expanded leaf, and those in width and thickness in the thirdly fully expanded leaf, which were at the leaf developmental stages P4 and P3, respectively, at the onset of the eCO2 treatment. The decreased blade length at eCO2 was associated with a decrease in the epidermal cell number on the adaxial side and a reduction in cell length on the abaxial side. The decreased width resulted from decreased numbers of small vascular bundles and epidermal cell files. The increased thickness was ascribed mainly to enhanced development of bundle sheath extensions at the ridges of vascular bundles. These observations enable us to identify the sites of action of eCO2 on rice leaf development.

Occurrence and forms of Kranz anatomy in photosynthetic organs and characterization of NAD-ME subtype C4 photosynthesis in Blepharis ciliaris (L.) B. L. Burtt (Acanthaceae).

PubMed

Akhani, Hossein; Ghasemkhani, Maraym; Chuong, Simon D X; Edwards, Gerald E

2008-01-01

Blepharis (Acanthaceae) is an Afroasiatic genus comprising 129 species which occur in arid and semi-arid habitats. This is the only genus in the family which is reported to have some C(4) species. Blepharis ciliaris (L.) B. L. Burtt. is a semi-desert species with distribution in Iran, Oman, and Pakistan. Its form of photosynthesis was investigated by studying different organs. C(4)-type carbon isotope composition, the presence of atriplicoid type Kranz anatomy, and compartmentation of starch all indicate performance of C(4) photosynthesis in cotyledons, leaves, and the lamina part of bracts. A continuous layer of distinctive bundle sheath cells (Kranz cells) encircle the vascular bundles in cotyledons and the lateral vascular bundles in leaves. In older leaves, there is extensive development of ground tissue in the midrib and the Kranz tissue becomes interrupted on the abaxial side, and then becomes completely absent in the mature leaf base. Cotyledons have 5-6 layers, and leaves 2-3 layers, of spongy chlorenchyma beneath the veins near the adaxial side of the leaf, indicating bifacial organization of chlorenchyma. As the plant matures, bracts and spines develop and contribute to carbon assimilation through an unusual arrangement of Kranz anatomy which depends on morphology and exposure to light. Stems do not contribute to carbon assimilation, as they lack chlorenchyma tissue and Kranz anatomy. Analysis of C(4) acid decarboxylases by western blot indicates B. ciliaris is an NAD-malic enzyme type C(4) species, which is consistent with the Kranz cells having chloroplasts with well-developed grana and abundant mitochondria.

Lodging Resistance of Japonica Rice (Oryza Sativa L.): Morphological and Anatomical Traits due to top-Dressing Nitrogen Application Rates.

PubMed

Zhang, Wujun; Wu, Longmei; Wu, Xiaoran; Ding, Yanfeng; Li, Ganghua; Li, Jingyong; Weng, Fei; Liu, Zhenghui; Tang, She; Ding, Chengqiang; Wang, Shaohua

2016-12-01

Lodging in rice production often limits grain yield and quality by breaking or bending stems. Excessive nitrogen (N) fertilizer rates are the cause of poor lodging resistance in rice, but little is known about the effect of top-dressing N application rates on the mechanical strength of japonica rice plants, especially how the anatomical structure in culms is affected by N. In this study, field experiments on two japonica rice varieties with three top-dressing N application rates, 0 kg N ha(-1) (LN), 135 kg N ha(-1) (MN), and 270 kg N ha(-1) (HN) as urea, were conducted. Wuyunjing23, a lodging-resistant japonica rice cultivar and W3668, a lodging-susceptible japonica rice cultivar were used. The lodging index, breaking strength, morphological and anatomical traits in culms were measured in this study. The visual lodging rate in japonica rice differed remarkably between genotypes and top-dressing N treatments. The higher lodging index of rice plants was primarily attributed to the weak breaking strength of the lower internodes. The longer elongated basal internodes were responsible for higher plant height and a higher lodging index. Correlation analysis showed that breaking strength was significantly and positively correlated with the thickness of the mechanical tissue but was significantly and negatively correlated with the inner diameter of the major axis (b2). With increasing top-dressing N rates, the sclerenchyma cells of the mechanical tissues and the vascular bundles of the Wuyunjing23 cultivar varied little. The plant height, inner diameter of the minor axis (a2) and b2 increased significantly, but the area of the large vascular bundle (ALVB) and the area of the small vascular bundle (ASVB) decreased significantly and resulted in lower stem strength and a higher lodging index under higher top-dressing N conditions. The culm diameter of the W3668 cultivar increased slightly with no significant difference, and the sclerenchyma cells in the mechanical tissues and vascular bundles showed deficient lignifications under high top-dressing N conditions. Moreover, the ALVB and the ASVB decreased significantly, while the area of air chambers (AAC) increased rapidly. An improvement in the lodging resistance of japonica rice plants could be achieved by reducing the length of the lower internodes, decreasing the inner culm diameter and developing a thicker mechanical tissue. Top-dressing N application increased the plant height and inner culm diameter and decreased the ALVB and the ASVB of the Wuyunjing23 cultivar and caused deficient lignified sclerenchyma cells, lowered the ALVB and the ASVB, and increased the AAC of the W3668 cultivar resulting in weaker stem strength and a higher lodging index.

Cadmium remobilization from shoot to grain is related to pH of vascular bundle in rice.

PubMed

Zhang, Bing-Lin; Ouyang, You-Nan; Xu, Jun-Ying; Liu, Ke

2018-01-01

The remobilization of cadmium (Cd) from shoots to grain is the key process to determine the Cd accumulation in grain. The apoplastic pH of plants is an important factor and signal in influencing on plant responding to environmental variation and inorganic elements uptake. It is proposed that pH of rice plants responds and influences on Cd remobilization from shoots to grain when rice is exposed to Cd stress. The results of hydroponic experiment showed that: pH of the rice leaf vascular bundles among 3 cultivars was almost increased, pH value of 1 cultivar was slightly increasing when rice plants were treated with Cd. The decrease degree of H + concentration in leaf vascular bundles was different among cultivars. The cultivar with higher decreasing in H + concentration, showed higher Cd transfer efficiency from shoots to grain. The H + concentration of leaf vascular bundles under normal condition was negatively correlated to cadmium accumulation in leaf. Moreover, pH change was related to Cd accumulation in shots and remobilization from shoots to grain. Uncovering the role of pH response is a key component for the understanding Cd uptake and remobilization mechanism for rice production. Copyright © 2017 Elsevier Inc. All rights reserved.

The KNOTTED-like genes of peach (Prunus persica L. Batsch) are differentially expressed during drupe growth and the class 1 KNOPE1 contributes to mesocarp development.

PubMed

Testone, Giulio; Condello, Emiliano; Di Giacomo, Elisabetta; Nicolodi, Chiara; Caboni, Emilia; Rasori, Angela; Bonghi, Claudio; Bruno, Leonardo; Bitonti, Maria Beatrice; Giannino, Donato

2015-08-01

The Knotted-like transcription factors (KNOX) contribute to plant organ development. The expression patterns of peach KNOX genes showed that the class 1 members act precociously (S1-S2 stages) and differentially during drupe growth. Specifically, the transcription of KNOPE1 and 6 decreased from early (cell division) to late (cell expansion) S1 sub-stages, whilst that of STMlike1, 2, KNOPE2, 2.1 ceased at early S1. The KNOPE1 role in mesocarp was further addressed by studying the mRNA localization in the pulp cells and vascular net at early and late S1. The message signal was first diffuse in parenchymatous cells and then confined to hypodermal cell layers, showing that the gene down-tuning accompanied cell expansion. As for bundles, the mRNA mainly featured in the procambium/phloem of collateral open types and subsequently in the phloem side of complex structures (converging bundles, ducts). The KNOPE1 overexpression in Arabidopsis caused fruit shortening, decrease of mesocarp cell size, diminution of vascular lignification together with the repression of the major gibberellin synthesis genes AtGA20ox1 and AtGA3ox1. Negative correlation between the expression of KNOPE1 and PpGA3ox1 was observed in four cultivars at S1, suggesting that the KNOPE1 repression of PpGA3ox1 may regulate mesocarp differentiation by acting on gibberellin homeostasis. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

A Preliminary Study on a Specifically Expressed Arabidopsis Promotor in Vascular Bundle

NASA Astrophysics Data System (ADS)

Yun-hong, Gu; Chuan-xiao, Xie; Li-fang, Wu; Zeng-liang, Yu; Guang-yong, Qin; Yu-ping, Huo

2003-04-01

From a population of about 3500 single plants in Arabidopsis promoter trapping bank, one plant whose GUS-gene had been specifically expressed in vascular bundle, was screened by the method of gus tissue staining. The T-DNA flanking sequence was amplified using TAIL-PCR. This band will be purified and connected to TA cloning vector. After sequencing and searching in the genebank, its function will be demonatrated through transformation.

Anatomical diversity of funicles in Leguminosae.

PubMed

Endo, Yasuhiko

2012-01-01

To clarify the diversity in funicular internal structures in Leguminosae, 59 legume species (classified into 46 genera, 20 tribes, and 3 subfamilies) were examined by a paraffin-sectioning method. The vascular bundles of legume funicles were clarified as collateral, amphicribral, or amphivasal. In species in which the funicular vascular bundle was collateral throughout the funicle, the xylem is positioned at the pericarpial side in the basal part of the funicle, and the xylem was always positioned at the micropylar side of the phloem in the apical end of the funicles. Whenever the seed direction (from hilum to the micropyle) faces the stylar side, the funicular vascular bundle appears to twist between the basal and the apical part of the funicle. This twist would involve a rotation of the seeds (ovules) during seed (ovule) development. This also may mean that the direction (from hilum to the micropyle) of legume seeds originally faces the pericarp.

Architecture of the human renal inner medulla and functional implications

PubMed Central

Wei, Guojun; Rosen, Seymour; Dantzler, William H.

2015-01-01

The architecture of the inner stripe of the outer medulla of the human kidney has long been known to exhibit distinctive configurations; however, inner medullary architecture remains poorly defined. Using immunohistochemistry with segment-specific antibodies for membrane fluid and solute transporters and other proteins, we identified a number of distinctive functional features of human inner medulla. In the outer inner medulla, aquaporin-1 (AQP1)-positive long-loop descending thin limbs (DTLs) lie alongside descending and ascending vasa recta (DVR, AVR) within vascular bundles. These vascular bundles are continuations of outer medullary vascular bundles. Bundles containing DTLs and vasa recta lie at the margins of coalescing collecting duct (CD) clusters, thereby forming two regions, the vascular bundle region and the CD cluster region. Although AQP1 and urea transporter UT-B are abundantly expressed in long-loop DTLs and DVR, respectively, their expression declines with depth below the outer medulla. Transcellular water and urea fluxes likely decline in these segments at progressively deeper levels. Smooth muscle myosin heavy chain protein is also expressed in DVR of the inner stripe and the upper inner medulla, but is sparsely expressed at deeper inner medullary levels. In rodent inner medulla, fenestrated capillaries abut CDs along their entire length, paralleling ascending thin limbs (ATLs), forming distinct compartments (interstitial nodal spaces; INSs); however, in humans this architecture rarely occurs. Thus INSs are relatively infrequent in the human inner medulla, unlike in the rodent where they are abundant. UT-B is expressed within the papillary epithelium of the lower inner medulla, indicating a transcellular pathway for urea across this epithelium. PMID:26290371

Pharmacognostic studies of the leaves and stem of Careya arborea Roxb.

PubMed Central

Gupta, Prakash Chandra; Sharma, Nisha; Rao, Ch V

2012-01-01

Objective To study detailed pharmacognostic profile of leaves and stem of Careya arborea (C. arborea) Roxb. (Lecthyidaceae), an important medicinal plant in the Indian system of medicine. Methods Leaf and stem samples of C. arborea were studied by macroscopical, microscopical, physicochemical, phytochemical, fluorescence analysis of powder of the plant and other methods for standardization recommended by WHO. Results Macroscopically, the leaves are simple, broadly obovate in shape, acuminate apex with crenate, dentate margin, petioles (0.1–1.8 cm) long. Microscopically, the leaf showed the presence of median large size vascular bundle covered with fibrous bundle sheath, arrangement of xylem in cup shape and presence of cortical vascular bundle, patches of sclerenchyma, phloem fibers in groups and brown pigment containing cells in stem are some of the diagnostic features noted from anatomical study. Powder microscopy of leaf revealed the presence of parenchyma cells, xylem with pitted vessels and epidermis with anisocytic stomata. The investigations also included leaf surface data; quantitative leaf microscopy and fluorescence analysis. Physiochemical parameters such as loss on drying, swelling index, extractive values and ash values were also determined and results showed that total ash of the stem bark was about two times higher than leaf and water soluble extractive value of leaf and stem bark was two times higher than alcohol soluble extractive value. Preliminary phytochemical screening showed the presence of triterpenoids, saponins, tannins and flavonoids. Conclusions The results of the study can serve as a valuable source of information and provide suitable standards for identification of this plant material in future investigations and applications. PMID:23569939

Magnetic resonance imaging reveals functional anatomy and biomechanics of a living dragon tree

PubMed Central

Hesse, Linnea; Masselter, Tom; Leupold, Jochen; Spengler, Nils; Speck, Thomas; Korvink, Jan Gerrit

2016-01-01

Magnetic resonance imaging (MRI) was used to gain in vivo insight into load-induced displacements of inner plant tissues making a non-invasive and non-destructive stress and strain analysis possible. The central aim of this study was the identification of a possible load-adapted orientation of the vascular bundles and their fibre caps as the mechanically relevant tissue in branch-stem-attachments of Dracaena marginata. The complex three-dimensional deformations that occur during mechanical loading can be analysed on the basis of quasi-three-dimensional data representations of the outer surface, the inner tissue arrangement (meristem and vascular system), and the course of single vascular bundles within the branch-stem-attachment region. In addition, deformations of vascular bundles could be quantified manually and by using digital image correlation software. This combination of qualitative and quantitative stress and strain analysis leads to an improved understanding of the functional morphology and biomechanics of D. marginata, a plant that is used as a model organism for optimizing branched technical fibre-reinforced lightweight trusses in order to increase their load bearing capacity. PMID:27604526

Phloem transport velocity varies over time and among vascular bundles during early cucumber seedling development.

PubMed

Savage, Jessica A; Zwieniecki, Maciej A; Holbrook, N Michele

2013-11-01

We use a novel dye-tracing technique to measure in vivo phloem transport velocity in cucumber (Cucumis sativus) plants during early seedling development. We focus on seedlings because of their importance in plant establishment and because they provide a simple source and sink model of phloem transport. The dye-tracing method uses a photodiode to track the movement of a bleach front of fluorescent dye traveling in the phloem from the cotyledons (source) to the roots (sink). During early seedling development, phloem transport velocity in this direction can change 2-fold depending on vascular connectivity and the number of actively growing sinks. Prior to leaf expansion, vascular bundles attached to the first developing leaf demonstrate a decline in basipetal phloem transport that can be alleviated by the leaf's removal. At this stage, seedlings appear carbon limited and phloem transport velocity is correlated with cotyledon area, a pattern that is apparent both during cotyledon expansion and after source area manipulation. When the first leaf transitions to a carbon source, seedling growth rate increases and basipetal phloem transport velocity becomes more stable. Because bundles appear to operate autonomously, transport velocity can differ among vascular bundles. Together, these results demonstrate the dynamic and heterogeneous nature of phloem transport and underline the need for a better understanding of how changes in phloem physiology impact growth and allocation at this critical stage of development.

Auxin efflux facilitator and auxin dynamism responsible for the gravity-regulated development of peg in cucumber seedlings

NASA Astrophysics Data System (ADS)

Takahashi, Hideyuki; Watanabe, Chiaki; Fujii, Nobuharu; Miyazawa, Yutaka

Cucumber seedlings develop a protuberance, peg, by which seed coats are pulled out just af-ter germination. The peg is usually formed on the lower side of the transition zone between hypocotyl and root of the seedlings grown in a horizontal position. Our previous spaceflight experiment showed that unilateral positioning of a peg in cucumber seedlings occurred due to its suppression on the upper side of the transition zone because seedlings grown in microgravity developed a peg on each side of the transition zone. We also showed that auxin was a major factor responsible for peg development. There was a redistribution of auxin in the gravistimu-lated transition zone, decreasing IAA level on the upper side, and IAA application induced a peg on both lower and upper sides of the transition zone. In addition, peg was released from its suppression in the seedlings treated with inhibitors of auxin efflux. Namely, two pegs devel-oped in the TIBA-treated seedlings even when they were grown in a horizontal position. These results imply that a reduction of auxin level due to its efflux is required for the suppression of peg development on the upper side of the transition zone in a horizontal position. To under-stand molecular mechanism underlying the negative control of morphogenesis by graviresponse in cucumber seedlings, we isolated cDNAs of auxin efflux facilitators, CsPINs, from cucumber and examined the expressions of their proteins, in relation to the redistribution of endogenous auxin and peg development. We isolated six cDNAs of PIN homologues CsPIN1 to CsPIN6 from cucumber. By immunohistochemical study using some of their anti-bodies, we revealed that CsPIN1 was localized in endodermis, vascular tissue and pith around the transition zone of cucumber seedlings. In cucumber seedlings grown in a vertical position with radicles pointing down, CsPIN1 in endodermal cells was mainly localized on the plasma membrane neighboring vascular bundle but not on the plasma membrane next to the cortex. This CsPIN1 localization could play a role in transporting auxin from cortex to vascular bundle. In both vascular and pith tissues, CsPIN1 was localized on the bottom plasma membrane of the cells, which could allow auxin to move toward the roots. In the seedlings grown in a horizontal position, endoder-mal cells situated above the vascular bundle localized CsPIN1 on the lower plasma membrane, whereas the polarized localization of CsPIN1 in endodermal cells situated below the vascular bundle became less clear. This differential expression of CsPIN1 in the endodermis commenced within 30 min after gravistimulation. We measured endogenous IAA contents in the transi-tion zone of the 24-hour-old seedlings. In the longitudinally halved transition zone of seedlings grown in a horizontal position, free IAA content was significantly lowered in the upper side, compared to that of the lower side or either side of the transition zone in a vertical position. When 24-hour-old seedlings grown in a vertical position were gravistimulated by reorienting them to the horizontal, free IAA in the lower side of the transition zone increased by 30 min after gravistimulation and eventually decreased to the control level by 180 min after gravistim-ulation. IAA content in the upper side of the transition zone did not change much and was comparable to that in the vertical transition zone during 180 min after gravistimulation. Thus, it appears that gravistimulation causes an immediate increase of IAA level in the lower side and its eventual decrease in the upper side of the transition zone. The gravity-induced changes in CsPIN1 localization in endodermal cells could be involved in auxin redistribution that leads to unilateral positioning of a peg in cucumber seedlings.

Hemangiopericytoma in the eyelid of a horse.

PubMed

Serena, A; Joiner, K S; Schumacher, J

2006-07-01

Hemangiopericytoma (HP) is a well-recognized neoplasm arising from vascular pericytes that has been reported only in the dog and man. In this study, we describe a 14-year-old female Arabian horse that was presented for surgical excision of a 2-cm-diameter expansile subcuticular mass in the right lower eyelid. Histologically, the mass consisted of loosely arranged interlacing streams and storiform bundles of spindle cells that often formed distinct whorls around a central capillary and bundles of collagen (Antoni A-like pattern). Immunohistochemical analysis revealed strong diffuse cytoplasmic immunoreactivity for vimentin and focal immunoreactivity for smooth muscle actin, whereas neoplastic cells did not stain for Factor VIII-related antigen, Glial fibrillary acidic protein (GFAP), or S100. On the basis of histomorphology and immunohistochemical reactivity, the present tumor was diagnosed as HP. To our knowledge, this is the first report describing a HP in a horse.

Auxin Influx Carriers Control Vascular Patterning and Xylem Differentiation in Arabidopsis thaliana

PubMed Central

Siligato, Riccardo; Alonso, Jose M.; Swarup, Ranjan; Bennett, Malcolm J.; Mähönen, Ari Pekka; Caño-Delgado, Ana I.; Ibañes, Marta

2015-01-01

Auxin is an essential hormone for plant growth and development. Auxin influx carriers AUX1/LAX transport auxin into the cell, while auxin efflux carriers PIN pump it out of the cell. It is well established that efflux carriers play an important role in the shoot vascular patterning, yet the contribution of influx carriers to the shoot vasculature remains unknown. Here, we combined theoretical and experimental approaches to decipher the role of auxin influx carriers in the patterning and differentiation of vascular tissues in the Arabidopsis inflorescence stem. Our theoretical analysis predicts that influx carriers facilitate periodic patterning and modulate the periodicity of auxin maxima. In agreement, we observed fewer and more spaced vascular bundles in quadruple mutants plants of the auxin influx carriers aux1lax1lax2lax3. Furthermore, we show AUX1/LAX carriers promote xylem differentiation in both the shoot and the root tissues. Influx carriers increase cytoplasmic auxin signaling, and thereby differentiation. In addition to this cytoplasmic role of auxin, our computational simulations propose a role for extracellular auxin as an inhibitor of xylem differentiation. Altogether, our study shows that auxin influx carriers AUX1/LAX regulate vascular patterning and differentiation in plants. PMID:25922946

Architecture of the human renal inner medulla and functional implications.

PubMed

Wei, Guojun; Rosen, Seymour; Dantzler, William H; Pannabecker, Thomas L

2015-10-01

The architecture of the inner stripe of the outer medulla of the human kidney has long been known to exhibit distinctive configurations; however, inner medullary architecture remains poorly defined. Using immunohistochemistry with segment-specific antibodies for membrane fluid and solute transporters and other proteins, we identified a number of distinctive functional features of human inner medulla. In the outer inner medulla, aquaporin-1 (AQP1)-positive long-loop descending thin limbs (DTLs) lie alongside descending and ascending vasa recta (DVR, AVR) within vascular bundles. These vascular bundles are continuations of outer medullary vascular bundles. Bundles containing DTLs and vasa recta lie at the margins of coalescing collecting duct (CD) clusters, thereby forming two regions, the vascular bundle region and the CD cluster region. Although AQP1 and urea transporter UT-B are abundantly expressed in long-loop DTLs and DVR, respectively, their expression declines with depth below the outer medulla. Transcellular water and urea fluxes likely decline in these segments at progressively deeper levels. Smooth muscle myosin heavy chain protein is also expressed in DVR of the inner stripe and the upper inner medulla, but is sparsely expressed at deeper inner medullary levels. In rodent inner medulla, fenestrated capillaries abut CDs along their entire length, paralleling ascending thin limbs (ATLs), forming distinct compartments (interstitial nodal spaces; INSs); however, in humans this architecture rarely occurs. Thus INSs are relatively infrequent in the human inner medulla, unlike in the rodent where they are abundant. UT-B is expressed within the papillary epithelium of the lower inner medulla, indicating a transcellular pathway for urea across this epithelium. Copyright © 2015 the American Physiological Society.

Biomechanics of selected arborescent and shrubby monocotyledons

PubMed Central

Haushahn, Tobias; Fink, Samuel; Speck, Thomas

2016-01-01

Main aims of the study are a deepened understanding of the mechanically relevant (ultra-)structures and the mechanical behaviour of various arborescent and shrubby monocotyledons and obtaining the structure–function relationships of different structurally conspicuous parts in Dracaena marginata stems. The stems of five different “woody” monocotyledon species were dissected and the mechanical properties of the most noticeable tissues in the five monocotyledons and, additionally, of individual vascular bundles in D. marginata, were tested under tensile stress. Results for Young’s moduli and density of these tissues were assessed as well as the area, critical strain, Young’s modulus and tensile strength of the vascular bundles in Dracaena marginata. These analyses allowed for generating a model for the mechanical interaction of tissues and vascular bundles of the stem in D. marginata as well as filling major “white spots” in property charts for biological materials. Additionally we shortly discuss the potential significance of such studies for the development of branched and unbranched bio-inspired fibre-reinforced materials and structures with enhanced properties. PMID:28144511

Phloem Transport Velocity Varies over Time and among Vascular Bundles during Early Cucumber Seedling Development1[C][W][OPEN

PubMed Central

Savage, Jessica A.; Zwieniecki, Maciej A.; Holbrook, N. Michele

2013-01-01

We use a novel dye-tracing technique to measure in vivo phloem transport velocity in cucumber (Cucumis sativus) plants during early seedling development. We focus on seedlings because of their importance in plant establishment and because they provide a simple source and sink model of phloem transport. The dye-tracing method uses a photodiode to track the movement of a bleach front of fluorescent dye traveling in the phloem from the cotyledons (source) to the roots (sink). During early seedling development, phloem transport velocity in this direction can change 2-fold depending on vascular connectivity and the number of actively growing sinks. Prior to leaf expansion, vascular bundles attached to the first developing leaf demonstrate a decline in basipetal phloem transport that can be alleviated by the leaf’s removal. At this stage, seedlings appear carbon limited and phloem transport velocity is correlated with cotyledon area, a pattern that is apparent both during cotyledon expansion and after source area manipulation. When the first leaf transitions to a carbon source, seedling growth rate increases and basipetal phloem transport velocity becomes more stable. Because bundles appear to operate autonomously, transport velocity can differ among vascular bundles. Together, these results demonstrate the dynamic and heterogeneous nature of phloem transport and underline the need for a better understanding of how changes in phloem physiology impact growth and allocation at this critical stage of development. PMID:24072581

Analysis of gene expression profiles for cell wall modifying proteins and ACC synthases in soybean cyst nematode colonized roots, adventitious rooting hypocotyls, root tips, flooded roots, and IBA and ACC treatment roots

USDA-ARS?s Scientific Manuscript database

We hypothesized that soybean cyst nematode (SCN) co-opts a part or all of one or more innate developmental process in soybean to establish its feeding structure, syncytium, in soybean roots. The syncytium in soybean roots is formed in a predominantly lateral direction within the vascular bundle by ...

Multi-instrumental Analysis of Tissues of Sunflower Plants Treated with Silver(I) Ions – Plants as Bioindicators of Environmental Pollution

PubMed Central

Krizkova, Sona; Ryant, Pavel; Krystofova, Olga; Adam, Vojtech; Galiova, Michaela; Beklova, Miroslava; Babula, Petr; Kaiser, Jozef; Novotny, Karel; Novotny, Jan; Liska, Miroslav; Malina, Radomir; Zehnalek, Josef; Hubalek, Jaromir; Havel, Ladislav; Kizek, Rene

2008-01-01

The aim of this work is to investigate sunflower plants response on stress induced by silver(I) ions. The sunflower plants were exposed to silver(I) ions (0, 0.1, 0.5, and 1 mM) for 96 h. Primarily we aimed our attention to observation of basic physiological parameters. We found that the treated plants embodied growth depression, coloured changes and lack root hairs. Using of autofluorescence of anatomical structures, such as lignified cell walls, it was possible to determine the changes of important shoot and root structures, mainly vascular bungles and development of secondary thickening. The differences in vascular bundles organisation, parenchymatic pith development in the root centre and the reduction of phloem part of vascular bundles were well observable. Moreover with increasing silver(I) ions concentration the vitality of rhizodermal cells declined; rhizodermal cells early necrosed and were replaced by the cells of exodermis. Further we employed laser induced breakdown spectroscopy for determination of spatial distribution of silver(I) ions in tissues of the treated plants. The Ag is accumulated mainly in near-root part of the sample. Moreover basic biochemical indicators of environmental stress were investigated. The total content of proteins expressively decreased with increasing silver(I) ions dose and the time of the treatment. As we compare the results obtained by protein analysis – the total protein contents in shoot as well as root parts – we can assume on the transport of the proteins from the roots to shoots. This phenomenon can be related with the cascade of processes connecting with photosynthesis. The second biochemical parameter, which we investigated, was urease activity. If we compared the activity in treated plants with control, we found out that presence of silver(I) ions markedly enhanced the activity of urease at all applied doses of this toxic metal. Finally we studied the effect of silver(I) ions on activity of urease in in vitro conditions. PMID:27879716

Structural and mechanical design of tissue interfaces in the giant reed Arundo donax.

PubMed

Rüggeberg, Markus; Burgert, Ingo; Speck, Thomas

2010-03-06

The culms of the giant reed Arundo donax represent slender tube-like structures. Several nodes along the culm, a ring of sclerenchymatous fibres in the periphery of the culm wall and numerous isolated vascular bundles enclosed by fibre rings in the culm wall function as stiffening elements. The bundles are embedded in lignified parenchyma. Micromechanical analysis indicated differences in stiffness between the individual tissues of more than one order of magnitude. In case of abrupt transitions in stiffness at the interfaces, stress discontinuities arise under dynamic loads. This eventually leads to critical shear stresses at cell ends, and culm failure may be initiated at these points. Pronounced mechanical differences between individual tissues can be compromised by gradual transitions at their interfaces. Ultrastructural and spectroscopic investigations with high spatial resolution revealed a gradual transition of cell parameters (cell wall area fraction and cell length). However, cell wall parameters (cellulose microfibril angle and lignin content) showed abrupt transitions or remained almost constant across the interfaces between various tissues. The design principles found at the interfaces between tissues in the culm walls of A. donax are discussed as an adaptation strategy to mechanical loads at different levels of hierarchy.

Structural and mechanical design of tissue interfaces in the giant reed Arundo donax

PubMed Central

Rüggeberg, Markus; Burgert, Ingo; Speck, Thomas

2010-01-01

The culms of the giant reed Arundo donax represent slender tube-like structures. Several nodes along the culm, a ring of sclerenchymatous fibres in the periphery of the culm wall and numerous isolated vascular bundles enclosed by fibre rings in the culm wall function as stiffening elements. The bundles are embedded in lignified parenchyma. Micromechanical analysis indicated differences in stiffness between the individual tissues of more than one order of magnitude. In case of abrupt transitions in stiffness at the interfaces, stress discontinuities arise under dynamic loads. This eventually leads to critical shear stresses at cell ends, and culm failure may be initiated at these points. Pronounced mechanical differences between individual tissues can be compromised by gradual transitions at their interfaces. Ultrastructural and spectroscopic investigations with high spatial resolution revealed a gradual transition of cell parameters (cell wall area fraction and cell length). However, cell wall parameters (cellulose microfibril angle and lignin content) showed abrupt transitions or remained almost constant across the interfaces between various tissues. The design principles found at the interfaces between tissues in the culm walls of A. donax are discussed as an adaptation strategy to mechanical loads at different levels of hierarchy. PMID:19726440

Effective reduction of cadmium accumulation in rice grain by expressing OsHMA3 under the control of the OsHMA2 promoter

PubMed Central

Shao, Ji Feng; Xia, Jixing; Yamaji, Naoki; Shen, Ren Fang; Ma, Jian Feng

2018-01-01

Abstract Reducing cadmium (Cd) accumulation in rice grain is an important issue for human health. The aim of this study was to manipulate both expression and tissue localization of OsHMA3, a tonoplast-localized Cd transporter, in the roots by expressing it under the control of the OsHMA2 promoter, which shows high expression in different organs including roots, nodes, and shoots. In two independent transgenic lines, the expression of OsHMA3 was significantly enhanced in all organs compared with non-transgenic rice. Furthermore, OsHMA3 protein was detected in the root pericycle cells and phloem region of both the diffuse vascular bundle and the enlarged vascular bundle of the nodes. At the vegetative stage, the Cd concentration in the shoots and xylem sap of the transgenic rice was significantly decreased, but that of the whole roots and root cell sap was increased. At the reproductive stage, the concentration of Cd, but not other essential metals, in the brown rice of transgenic lines was decreased to less than one-tenth that of the non-transgenic rice. These results indicate that expression of OsHMA3 under the control of the OsHMA2 promoter can effectively reduce Cd accumulation in rice grain through sequestering more Cd into the vacuoles of various tissues. PMID:29562302

Effective reduction of cadmium accumulation in rice grain by expressing OsHMA3 under the control of the OsHMA2 promoter.

PubMed

Shao, Ji Feng; Xia, Jixing; Yamaji, Naoki; Shen, Ren Fang; Ma, Jian Feng

2018-04-27

Reducing cadmium (Cd) accumulation in rice grain is an important issue for human health. The aim of this study was to manipulate both expression and tissue localization of OsHMA3, a tonoplast-localized Cd transporter, in the roots by expressing it under the control of the OsHMA2 promoter, which shows high expression in different organs including roots, nodes, and shoots. In two independent transgenic lines, the expression of OsHMA3 was significantly enhanced in all organs compared with non-transgenic rice. Furthermore, OsHMA3 protein was detected in the root pericycle cells and phloem region of both the diffuse vascular bundle and the enlarged vascular bundle of the nodes. At the vegetative stage, the Cd concentration in the shoots and xylem sap of the transgenic rice was significantly decreased, but that of the whole roots and root cell sap was increased. At the reproductive stage, the concentration of Cd, but not other essential metals, in the brown rice of transgenic lines was decreased to less than one-tenth that of the non-transgenic rice. These results indicate that expression of OsHMA3 under the control of the OsHMA2 promoter can effectively reduce Cd accumulation in rice grain through sequestering more Cd into the vacuoles of various tissues.

Phytotoxic Mechanism of Nanoparticles: Destruction of Chloroplasts and Vascular Bundles and Alteration of Nutrient Absorption

NASA Astrophysics Data System (ADS)

Nhan, Le Van; Ma, Chuanxin; Rui, Yukui; Liu, Shutong; Li, Xuguang; Xing, Baoshan; Liu, Liming

2015-06-01

This study focused on determining the phytotoxic mechanism of CeO2 nanoparticles (NPs): destroying chloroplasts and vascular bundles and altering absorption of nutrients on conventional and Bt-transgenic cottons. Experiments were designed with three concentrations of CeO2 NPs including: 0, 100 and 500 mg·L-1, and each treatment was three replications. Results indicate that absorbed CeO2 nanoparticles significantly reduced the Zn, Mg, Fe, and P levels in xylem sap compared with the control group and decreased indole-3-acetic acid (IAA) and abscisic acid (ABA) concentrations in the roots of conventional cotton. Transmission electron microscopy (TEM) images revealed that CeO2 NPs were absorbed into the roots and subsequently transported to the stems and leaves of both conventional and Bt-transgenic cotton plants via xylem sap. In addition, the majority of aggregated CeO2 NPs were attached to the external surface of chloroplasts, which were swollen and ruptured, especially in Bt-transgenic cotton. The vascular bundles were destroyed by CeO2 nanoparticles, and more damage was observed in transgenic cotton than conventional cotton.

From proto-Kranz to C4 Kranz: building the bridge to C4 photosynthesis.

PubMed

Sage, Rowan F; Khoshravesh, Roxana; Sage, Tammy L

2014-07-01

In this review, we examine how the specialized "Kranz" anatomy of C4 photosynthesis evolved from C3 ancestors. Kranz anatomy refers to the wreath-like structural traits that compartmentalize the biochemistry of C4 photosynthesis and enables the concentration of CO2 around Rubisco. A simplified version of Kranz anatomy is also present in the species that utilize C2 photosynthesis, where a photorespiratory glycine shuttle concentrates CO2 into an inner bundle-sheath-like compartment surrounding the vascular tissue. C2 Kranz is considered to be an intermediate stage in the evolutionary development of C4 Kranz, based on the intermediate branching position of C2 species in 14 evolutionary lineages of C4 photosynthesis. In the best-supported model of C4 evolution, Kranz anatomy in C2 species evolved from C3 ancestors with enlarged bundle sheath cells and high vein density. Four independent lineages have been identified where C3 sister species of C2 plants exhibit an increase in organelle numbers in the bundle sheath and enlarged bundle sheath cells. Notably, in all of these species, there is a pronounced shift of mitochondria to the inner bundle sheath wall, forming an incipient version of the C2 type of Kranz anatomy. This incipient version of C2 Kranz anatomy is termed proto-Kranz, and is proposed to scavenge photorespiratory CO2. By doing so, it may provide fitness benefits in hot environments, and thus represent a critical first stage of the evolution of both the C2 and C4 forms of Kranz anatomy. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Transcript profiling of a novel plant meristem, the monocot cambium

Treesearch

Matthew Zinkgraf; Suzanne Gerttula; Andrew Groover

2017-01-01

While monocots lack the ability to produce a vascular cambium or woody growth, some monocot lineages evolved a novel lateral meristem, the monocot cambium, which supports secondary radial growth of stems. In contrast to the vascular cambium found in woody angiosperm and gymnosperm species, the monocot cambium produces secondary vascular bundles, which have an...

Multi-instrumental Analysis of Tissues of Sunflower Plants Treated with Silver(I) Ions - Plants as Bioindicators of Environmental Pollution.

PubMed

Krizkova, Sona; Ryant, Pavel; Krystofova, Olga; Adam, Vojtech; Galiova, Michaela; Beklova, Miroslava; Babula, Petr; Kaiser, Jozef; Novotny, Karel; Novotny, Jan; Liska, Miroslav; Malina, Radomir; Zehnalek, Josef; Hubalek, Jaromir; Havel, Ladislav; Kizek, Rene

2008-01-24

The aim of this work is to investigate sunflower plants response on stressinduced by silver(I) ions. The sunflower plants were exposed to silver(I) ions (0, 0.1, 0.5,and 1 mM) for 96 h. Primarily we aimed our attention to observation of basic physiologicalparameters. We found that the treated plants embodied growth depression, coloured changes and lack root hairs. Using of autofluorescence of anatomical structures, such aslignified cell walls, it was possible to determine the changes of important shoot and rootstructures, mainly vascular bungles and development of secondary thickening. Thedifferences in vascular bundles organisation, parenchymatic pith development in the rootcentre and the reduction of phloem part of vascular bundles were well observable.Moreover with increasing silver(I) ions concentration the vitality of rhizodermal cellsdeclined; rhizodermal cells early necrosed and were replaced by the cells of exodermis.Further we employed laser induced breakdown spectroscopy for determination of spatialdistribution of silver(I) ions in tissues of the treated plants. The Ag is accumulated mainlyin near-root part of the sample. Moreover basic biochemical indicators of environmentalstress were investigated. The total content of proteins expressively decreased withincreasing silver(I) ions dose and the time of the treatment. As we compare the resultsobtained by protein analysis - the total protein contents in shoot as well as root parts - wecan assume on the transport of the proteins from the roots to shoots. This phenomenon canbe related with the cascade of processes connecting with photosynthesis. The secondbiochemical parameter, which we investigated, was urease activity. If we compared theactivity in treated plants with control, we found out that presence of silver(I) ions markedlyenhanced the activity of urease at all applied doses of this toxic metal. Finally we studiedthe effect of silver(I) ions on activity of urease in in vitro conditions.

PHARMACOGNOSTIC STUDIES ON THE FRUITS OF JATROPHA CURCAS LINN

PubMed Central

Joseph, G.V.R.

2001-01-01

Present paper deals with the pharmacognostic studies of the fruits of J. curcas Linn. The 75-80 cells thick pericarp is differentiated into epicarp, mesocarp and endocarp. Mesocarpic zone embeds non-articulated laticifers, tannin containing idioblasts and randomly distributed vascular bundles. Endocarp shows the occurrence of fibrous sclereids. Preliminary phytochemical screening of the drug powder shows the presence of alkaloids, carbohydrates, glycosides and tannins. Clinical evaluation of the fresh fruit juice has shown it s anti gingivitic property. PMID:22557042

Dianthus chinensis L.: The Structural Difference between Vascular Bundles in the Placenta and Ovary Wall Suggests Their Different Origin

PubMed Central

Guo, Xue-Min; Yu, Ying-Ying; Bai, Lan; Gao, Rong-Fu

2017-01-01

Dianthus chinensis is a perennial herbaceous plant with great ornamental, botanical, ecological, and medicinal value. The pistil of D. chinensis is composed of two fused carpels with free central placenta and two separate styles. The placenta is a columnar structure extending about two-thirds the length of the maturing fruit, which is typical of the Caryophyllaceous. Traditionally, free central placenta is thought to have evolved from axial placenta by septal disappearance, and axial placenta to have occurred through fusion of conduplicate carpels with marginal placenta. However, the traditional opinion is becoming more and more inconsistent with the new data gained in recent research of angiosperm systematics. To clarify the origin of D. chinensis pistil, the present anatomical study was carried out. The results show that the vascular system of placenta is independent to that of the ovary wall in D. chinensis. Moreover, in the central part of placenta there are one or two amphicribral bundles, and correspondingly numerous ones in the pistil which supply the ovules/seeds. It is obvious that the central amphicribral bundles in placenta are comparable to the counterparts in branches but not to those in leaves or their derivatives. Therefore, it is reasonable to deduce that the placenta of D. chinensis was not derived from conduplicate carpels through fusion of collateral vascular bundles, and actually a floral axis with ovules/seeds laterally adhering. On the contrary, the ovary wall was the lateral appendages of the floral axis. The result of the present study is completely in agreement with Unifying Theory, in which the placenta is taken as an ovule-bearing branch. Except for D. chinensis, the similar vascular organization has been observed in placenta of numerous isolated taxa. But till now, it is uncertain that whether this vascular organization pattern is popular in the whole angiosperms or not. More intensive and extensive investigations are needed. PMID:29250086

Dianthus chinensis L.: The Structural Difference between Vascular Bundles in the Placenta and Ovary Wall Suggests Their Different Origin.

PubMed

Guo, Xue-Min; Yu, Ying-Ying; Bai, Lan; Gao, Rong-Fu

2017-01-01

Dianthus chinensis is a perennial herbaceous plant with great ornamental, botanical, ecological, and medicinal value. The pistil of D. chinensis is composed of two fused carpels with free central placenta and two separate styles. The placenta is a columnar structure extending about two-thirds the length of the maturing fruit, which is typical of the Caryophyllaceous. Traditionally, free central placenta is thought to have evolved from axial placenta by septal disappearance, and axial placenta to have occurred through fusion of conduplicate carpels with marginal placenta. However, the traditional opinion is becoming more and more inconsistent with the new data gained in recent research of angiosperm systematics. To clarify the origin of D. chinensis pistil, the present anatomical study was carried out. The results show that the vascular system of placenta is independent to that of the ovary wall in D. chinensis . Moreover, in the central part of placenta there are one or two amphicribral bundles, and correspondingly numerous ones in the pistil which supply the ovules/seeds. It is obvious that the central amphicribral bundles in placenta are comparable to the counterparts in branches but not to those in leaves or their derivatives. Therefore, it is reasonable to deduce that the placenta of D. chinensis was not derived from conduplicate carpels through fusion of collateral vascular bundles, and actually a floral axis with ovules/seeds laterally adhering. On the contrary, the ovary wall was the lateral appendages of the floral axis. The result of the present study is completely in agreement with Unifying Theory, in which the placenta is taken as an ovule-bearing branch. Except for D. chinensis , the similar vascular organization has been observed in placenta of numerous isolated taxa. But till now, it is uncertain that whether this vascular organization pattern is popular in the whole angiosperms or not. More intensive and extensive investigations are needed.

Developmental and environmental regulation of the Nicotiana plumbaginifolia cytosolic Cu/Zn-superoxide dismutase promoter in transgenic tobacco.

PubMed Central

Hérouart, D; Van Montagu, M; Inzé, D

1994-01-01

Superoxide dismutases (SODs) play a key role in the cellular defense against reactive oxygen species. To study the transcriptional regulation at the cellular level, the promoter of the Nicotiana plumbaginifolia cytosolic gene encoding Cu/ZnSOD (SODCc) was fused to the beta-glucuronidase (GUS) reporter gene (gusA) and analyzed in transgenic tobacco plants. The promoter was highly active in vascular bundles of leaves and stems, where it is confined to phloem cells. In flowers, GUS activity was detected in ovules and pollen grains, in pigmented tissues of petals, and in vascular tissue of ovaries and anthers. In response to treatment with the superoxide-generating herbicide paraquat, very strong GUS staining was observed in photosynthetically active cells of leaves and in some epidermal root cells of seedlings. The expression of the SODCc-gusA was also induced in seedlings after heat shock and chilling and after treatment with sulfhydryl antioxidants such as reduced glutathione and cysteine. It is postulated that SODCc expression is directly linked to a cell-specific production of excess superoxide radicals in the cytosol. PMID:8165260

Developmental and environmental regulation of the Nicotiana plumbaginifolia cytosolic Cu/Zn-superoxide dismutase promoter in transgenic tobacco.

PubMed

Hérouart, D; Van Montagu, M; Inzé, D

1994-03-01

Superoxide dismutases (SODs) play a key role in the cellular defense against reactive oxygen species. To study the transcriptional regulation at the cellular level, the promoter of the Nicotiana plumbaginifolia cytosolic gene encoding Cu/ZnSOD (SODCc) was fused to the beta-glucuronidase (GUS) reporter gene (gusA) and analyzed in transgenic tobacco plants. The promoter was highly active in vascular bundles of leaves and stems, where it is confined to phloem cells. In flowers, GUS activity was detected in ovules and pollen grains, in pigmented tissues of petals, and in vascular tissue of ovaries and anthers. In response to treatment with the superoxide-generating herbicide paraquat, very strong GUS staining was observed in photosynthetically active cells of leaves and in some epidermal root cells of seedlings. The expression of the SODCc-gusA was also induced in seedlings after heat shock and chilling and after treatment with sulfhydryl antioxidants such as reduced glutathione and cysteine. It is postulated that SODCc expression is directly linked to a cell-specific production of excess superoxide radicals in the cytosol.

Symplasmic transport and phloem loading in gymnosperm leaves

PubMed Central

Liesche, Johannes; Martens, Helle Juel

2010-01-01

Despite more than 130 years of research, phloem loading is far from being understood in gymnosperms. In part this is due to the special architecture of their leaves. They differ from angiosperm leaves among others by having a transfusion tissue between bundle sheath and the axial vascular elements. This article reviews the somewhat inaccessible and/or neglected literature and identifies the key points for pre-phloem transport and loading of photoassimilates. The pre-phloem pathway of assimilates is structurally characterized by a high number of plasmodesmata between all cell types starting in the mesophyll and continuing via bundle sheath, transfusion parenchyma, Strasburger cells up to the sieve elements. Occurrence of median cavities and branching indicates that primary plasmodesmata get secondarily modified and multiplied during expansion growth. Only functional tests can elucidate whether this symplasmic pathway is indeed continuous for assimilates, and if phloem loading in gymnosperms is comparable with the symplasmic loading mode in many angiosperm trees. In contrast to angiosperms, the bundle sheath has properties of an endodermis and is equipped with Casparian strips or other wall modifications that form a domain border for any apoplasmic transport. It constitutes a key point of control for nutrient transport, where the opposing flow of mineral nutrients and photoassimilates has to be accommodated in each single cell, bringing to mind the principle of a revolving door. The review lists a number of experiments needed to elucidate the mode of phloem loading in gymnosperms. PMID:21107620

Cell lineage in vascularized bone transplantation.

PubMed

Willems, Wouter F; Larsen, Mikko; Friedrich, Patricia F; Bishop, Allen T

2014-01-01

The biology behind vascularized bone allotransplantation remains largely unknown. We aim to study cell traffic between donor and recipient following bone auto-, and allografting. Vascularized femoral transplantation was performed with arteriovenous bundle implantation and short-term immunosuppression. Twenty male Piebald Virol Glaxo (PVG; RT1(c) ) rats received isotransplants from female PVG (RT1(c) ) rats and 22 male PVG rats received allografts from female Dark Agouti rats (DA, RT1(a) ), representing a major histocompatibility mismatch. Both groups were randomly analyzed at 4 or 18 weeks. Bone remodeling areas (inner and outer cortical samples) were labeled and laser capture microdissected. Analysis of sex-mismatch genes by real-time reverse transcription-polymerase chain reaction provided the relative Expression Ratio (rER) of donor (female) to recipient (male) cells. The rER was 0.456 ± 0.266 at 4 weeks and 0.749 ± 0.387 at 18 weeks (p = 0.09) in allotransplants. In isotransplants, the rER was 0.412 ± 0.239 and 0.467 ± 0.252 at 4 and 18 weeks, respectively (p = 0.21). At 4 weeks, the rER at the outer cortical area of isotransplants was significantly lower in isotransplants as compared with allotransplants (0.247 ± 0.181 vs. 0.549 ± 0.184, p = 0.007). Cells in the inner and outer cortical bone remodeling areas in isotransplants were mainly donor derived (rER < 0.5) at 18 weeks, whereas allotransplants contained mainly recipient-derived cells (rER > 0.5) at 18 weeks. Applying novel methodology, we describe detailed cell traffic in vascularized bone transplants, elaborating our comprehension on bone transplantation. Copyright © 2013 Wiley Periodicals, Inc.

Dirigent proteins and dirigent sites in lignifying tissues

NASA Technical Reports Server (NTRS)

Burlat, V.; Kwon, M.; Davin, L. B.; Lewis, N. G.

2001-01-01

Tissue-specific dirigent protein gene expression and associated dirigent (site) localization were examined in various organs of Forsythia intermedia using tissue printing, in situ mRNA hybridization and immunolabeling techniques, respectively. Dirigent protein gene expression was primarily noted in the undifferentiated cambial regions of stem sections, whereas dirigent protein sites were detected mainly in the vascular cambium and ray parenchyma cell initials. Immunolocalization also revealed cross-reactivity with particular regions of the lignified cell walls, these being coincident with the known sites of initiation of lignin deposition. These latter regions are considered to harbor contiguous arrays of dirigent (monomer binding) sites for initiation of lignin biopolymer assembly. Dirigent protein mRNA expression was also localized in the vascular regions of roots and petioles, whereas in leaves the dirigent sites were primarily associated with the palisade layers and the vascular bundle. That is, dirigent protein mediated lignan biosynthesis was initiated primarily in the cambium and ray cell initial regions of stems as well as in the leaf palisade layers, this being in accordance with the occurrence of the lignans for defense purposes. Within lignified secondary xylem cell walls, however, dirigent sites were primarily localized in the S(1) sublayer and compound middle lamella, these being coincident with previously established sites for initiation of macromolecular lignin biosynthesis. Once initiation occurs, lignification is proposed to continue through template polymerization.

GIGANTEA directly activates Flowering Locus T in Arabidopsis thaliana.

PubMed

Sawa, Mariko; Kay, Steve A

2011-07-12

Plants perceive environmental signals such as day length and temperature to determine optimal timing for the transition from vegetative to floral stages. Arabidopsis flowers under long-day conditions through the CONSTANS (CO)-FLOWERING LOCUS T (FT) regulatory module. It is thought that the environmental cues for photoperiodic control of flowering are initially perceived in the leaves. We have previously shown that GIGANTEA (GI) regulates the timing of CO expression, together with FLAVIN-BINDING, KELCH REPEAT, F BOX protein 1. Normally, CO and FT are expressed exclusively in vascular bundles, whereas GI is expressed in various tissues. To better elucidate the role of tissue-specific expression of GI in the flowering pathway, we established transgenic lines in which GI is expressed exclusively in mesophyll, vascular bundles, epidermis, shoot apical meristem, or root. We found that GI expressed in either mesophyll or vascular bundles rescues the late-flowering phenotype of the gi-2 loss-of-function mutant under both short-day and long-day conditions. Interestingly, GI expressed in mesophyll or vascular tissues increases FT expression without up-regulating CO expression under short-day conditions. Furthermore, we examined the interaction between GI and FT repressors in mesophyll. We found that GI can bind to three FT repressors: SHORT VEGETATIVE PHASE (SVP), TEMPRANILLO (TEM)1, and TEM2. Finally, our chromatin immunoprecipitation experiments showed that GI binds to FT promoter regions that are near the SVP binding sites. Taken together, our data further elucidate the multiple roles of GI in the regulation of flowering time.

Specialised sympathetic neuroeffector associations in immature rat iris arterioles

PubMed Central

SANDOW, SHAUN L.; HILL, CARYL E.

1999-01-01

Sympathetic nerve-mediated vasoconstriction in iris arterioles of mature rats occurs via the activation of α1B-adrenoceptors alone, while in immature rat iris arterioles, vasoconstriction occurs via activation of both α1- and α2-adrenoceptors. In mature rats the vast majority of sympathetic varicosities form close neuroeffector junctions. Serial section electron microscopy of 14 d iris arterioles has been used to determine whether restriction in physiological receptor types with age may result from the establishment of these close neuroeffector junctions. Ninety varicosities which lay within 4 μm of arteriolar smooth muscle were followed for their entire length. Varicosities rarely contained dense cored vesicles even after treatment with 5-hydroxydopamine. 47% of varicosities formed close associations with muscle cells and 88% formed close associations with muscle cells or melanocytes. Varicosities in bundles were as likely as single varicosities to form close associations with vascular smooth muscle cells, although the distribution of synaptic vesicles in single varicosities did not show the asymmetric accumulation towards the smooth muscle cells seen in the varicosities in bundles which were frequently clustered together. We conclude that restriction of physiological receptor types during development does not appear to correlate with the establishment of close neuroeffector junctions, although changes in presynaptic structures may contribute to the refinement of postsynaptic responses. PMID:10529061

Microscopic diagnosis of the leaf and stem of Piper solmsianum C.DC.

PubMed

Bertocco, A R P; Migacz, I P; Santos, V L P; Franco, C R C; Silva, R Z; Yunes, R A; Cechinel-Filho, V; Budel, J M

2017-08-01

Piper solmsianum C.DC., which is popularly known as pariparoba, is a shrub that measures 1-3 m in height and it inhabits areas with wet tropical soils. The objective of this study was to analyze the leaf and stem anatomy using light microscopy, scanning electron micrographs, and energy-dispersive X-ray spectroscopy in order to provide information for species identification. The anatomical profile showed the following main microscopic markers: hypostomatic leaf; hypodermis layer on both sides; pearl glands; biconvex midrib shape; five collateral vascular bundles in open arc with the central bundle larger than the others; circular stem shape; collateral vascular bundles arranged in two rings; sinuous sclerenchymatic sheath in the pith; secretory idioblasts; and starch grains in the mesophyll, in the ground parenchyma of the midrib, petiole, and in the stem; and six morphotypes of calcium oxalate crystals (styloids, cuneiform, tabular crystal rosettes, cuneiform crystal rosettes, elongated square dipyramids, as well as very elongated square dipyramids). © 2017 Wiley Periodicals, Inc.

OsAGSW1, an ABC1-like kinase gene, is involved in the regulation of grain size and weight in rice.

PubMed

Li, Tao; Jiang, Jieming; Zhang, Shengchun; Shu, Haoran; Wang, Yaqin; Lai, Jianbin; Du, Jinju; Yang, Chengwei

2015-09-01

Grain shape and weight are two determining agronomic traits of rice yield. ABC1 (Activity of bc1 complex) is a newly found atypical kinase in plants. Here, we report on an ABC1 protein kinase gene, OsAGSW1 (ABC1-like kinase related to Grain size and Weight). Expression of OsAGSW1-GFP in rice revealed that OsAGSW1 is localized to the chloroplasts in rice. Analysis of OsAGSW1 promoter::β-glucuronidase transgenic rice indicated that this gene was highly expressed in vascular bundles in shoot, hull and caryopsis. Furthermore, OsAGSW1-RNAi and overexpressed transgenic rice lines were generated. Stable transgenic lines overexpressing OsAGSW1 exhibited a phenotype with a significant increase in grain size, grain weight, grain filling rate and 1000-grain weight compared with the wild-type and RNAi transgenic plants. Microscopy analysis showed that spikelet hulls just before heading were different in the OsAGSW1-overexpressed plants compared with wild-type and OsAGSW1 RNAi rice. Further cytological analysis showed that the number of external parenchyma cells in rice hulls of OsAGSW1-overexpressed plants increased, leading to wider and longer spikelet hulls than those of the wild-type and OsAGSW1-RNAi plants. The vascular cross-sectional area in lemma, carpopodium and ovules also strikingly increased and area of both xylem and phloem were enlarged in the OsAGSW1-overexpressed plants. Thus, our results demonstrated that OsAGSW1 plays an important role in seed shape and size of rice by regulating the number of external parenchyma cells and the development of vascular bundles, providing a new insight into the functions of ABC1 genes in plants. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

The accumulation and localization of chalcone synthase in grapevine (Vitis vinifera L.).

PubMed

Wang, Huiling; Wang, Wei; Zhan, JiCheng; Yan, Ailing; Sun, Lei; Zhang, Guojun; Wang, Xiaoyue; Ren, Jiancheng; Huang, Weidong; Xu, Haiying

2016-09-01

Chalcone synthase (CHS, E.C.2.3.1.74) is the first committed enzyme in the flavonoid pathway. Previous studies have primarily focused on the cloning, expression and regulation of the gene at the transcriptional level. Little is yet known about the enzyme accumulation, regulation at protein level, as well as its localization in grapevine. In present study, the accumulation, tissue and subcellular localization of CHS in different grapevine tissues (Vitis vinifera L. Cabernet Sauvignon) were investigated via the techniques of Western blotting, immunohistochemical localization, immunoelectron microscopy and confocal microscopy. The results showed that CHS were mainly accumulated in the grape berry skin, leaves, stem tips and stem phloem, correlated with flavonoids accumulation. The accumulation of CHS is developmental dependent in grape berry skin and flesh. Immunohistochemical analysis revealed that CHS were primarily localized in the exocarp and vascular bundles of the fruits during berry development; in palisade, spongy tissues and vascular bundles of the leaves; in the primary phloem and pith ray in the stems; in the growth point, leaf primordium, and young leaves of leaf buds; and in the endoderm and primary phloem of grapevine roots. Furthermore, at the subcellular level, the cell wall, cytoplasm and nucleus localized patterns of CHS were observed in the grapevine vegetative tissue cells. Results above indicated that distribution of CHS in grapevine was organ-specific and tissue-specific. This work will provide new insight for the biosynthesis and regulation of diverse flavonoid compounds in grapevine. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Matrix remodeling between cells and cellular interactions with collagen bundle

NASA Astrophysics Data System (ADS)

Kim, Jihan; Sun, Bo

When cells are surrounded by complex environment, they continuously probe and interact with it by applying cellular traction forces. As cells apply traction forces, they can sense rigidity of their local environment and remodel the matrix microstructure simultaneously. Previous study shows that single human carcinoma cell (MDA-MB-231) remodeled its surrounding extracellular matrix (ECM) and the matrix remodeling was reversible. In this study we examined the matrix microstructure between cells and cellular interaction between them using quantitative confocal microscopy. The result shows that the matrix microstructure is the most significantly remodeled between cells consisting of aligned, and densified collagen fibers (collagen bundle)., the result shows that collagen bundle is irreversible and significantly change micromechanics of ECM around the bundle. We further examined cellular interaction with collagen bundle by analyzing dynamics of actin and talin formation along with the direction of bundle. Lastly, we analyzed dynamics of cellular protrusion and migrating direction of cells along the bundle.

Increased leaf angle1, a Raf-like MAPKKK that interacts with a nuclear protein family, regulates mechanical tissue formation in the Lamina joint of rice.

PubMed

Ning, Jing; Zhang, Baocai; Wang, Nili; Zhou, Yihua; Xiong, Lizhong

2011-12-01

Mitogen-activated protein kinase kinase kinases (MAPKKKs), which function at the top level of mitogen-activated protein kinase cascades, are clustered into three groups. However, no Group C Raf-like MAPKKKs have yet been functionally identified. We report here the characterization of a rice (Oryza sativa) mutant, increased leaf angle1 (ila1), resulting from a T-DNA insertion in a Group C MAPKKK gene. The increased leaf angle in ila1 is caused by abnormal vascular bundle formation and cell wall composition in the leaf lamina joint, as distinct from the mechanism observed in brassinosteroid-related mutants. Phosphorylation assays revealed that ILA1 is a functional kinase with Ser/Thr kinase activity. ILA1 is predominantly resident in the nucleus and expressed in the vascular bundles of leaf lamina joints. Yeast two-hybrid screening identified six closely related ILA1 interacting proteins (IIPs) of unknown function. Using representative IIPs, the interaction of ILA1 and IIPs was confirmed in vivo. IIPs were localized in the nucleus and showed transactivation activity. Furthermore, ILA1 could phosphorylate IIP4, indicating that IIPs may be the downstream substrates of ILA1. Microarray analyses of leaf lamina joints provided additional evidence for alterations in mechanical strength in ila1. ILA1 is thus a key factor regulating mechanical tissue formation at the leaf lamina joint.

CD34-reactive fibrous papule of the nose.

PubMed

Shea, C R; Salob, S; Reed, J A; Lugo, J; McNutt, N S

1996-08-01

In human skin, the CD34 antigen is expressed on endothelium, periadnexal cells, and a population of reticular dermal interstitial cells. CD34 expression is characteristic of dermatofibrosarcoma protuberans and several other neoplasms, but not of typical fibrous papules of the nose. We describe a 16-year-old white girl with a slowly growing papule on the nose. Histopathology showed a dermal tumor with a superficial component of branched, thin-walled blood vessels and a deeper component of benign-appearing, spindle-shaped cells. These cells uniformly and strongly expressed CD34, but not factor XIIIa or markers of melanocytic, neural, muscular, vascular, or histiocytic differentiation. We consider this lesion a CD34-reactive fibrous papule. This benign tumor must be clearly distinguished from dermatofibrosarcoma protuberans, which also is composed of bundles of CD34-reactive spindle-shaped cells in most cases but has locally aggressive behavior.

Espins and the actin cytoskeleton of hair cell stereocilia and sensory cell microvilli

PubMed Central

Sekerková, Gabriella; Zheng, Lili; Loomis, Patricia A.; Mugnaini, Enrico; Bartles, James R.

2008-01-01

The espins are novel actin-bundling proteins that are produced in multiple isoforms from a single gene. They are present at high concentration in the parallel actin bundle of hair cell stereocilia and are the target of deafness mutations in mice and humans. Espins are also enriched in the microvilli of taste receptor cells, solitary chemoreceptor cells, vomeronasal sensory neurons and Merkel cells, suggesting that espins play important roles in the microvillar projections of vertebrate sensory cells. Espins are potent actin-bundling proteins that are not inhibited by Ca2+. In cells, they efficiently elongate parallel actin bundles and, thereby, help determine the steady-state length of microvilli and stereocilia. Espins bind actin monomer via their WH2 domain and can assemble actin bundles in cells. Certain espin isoforms can also bind phosphatidylinositol 4,5-bisphosphate, profilins or SH3 proteins. These biological activities distinguish espins from other actin-bundling proteins and may make them well-suited to sensory cells. PMID:16909209

The Third, Intensive Care Bundle With Blood Pressure Reduction in Acute Cerebral Hemorrhage Trial

ClinicalTrials.gov

2018-04-24

Cerebral Hemorrhage; Stroke; Hypertension; Diabetes; Anticoagulant-induced Bleeding; Cerebral Vascular Disorder; Brain Disorder; Hemorrhage; Intracranial Hemorrhages; Cardiovascular Diseases; Central Nervous System Diseases

The Main Transport System in the Wheat Ear

NASA Technical Reports Server (NTRS)

Stieber, Joseph; Stieber, Joli; Bubenheim, David L.; Kliss, Mark (Technical Monitor)

1996-01-01

The vascular system in the rachis, rachilla, and florets of the wheat ear was studied by direct microscopical observation of cleaned semi longitudinal sections. A periodic repetitive change of amphivasal and collateral phases was found along each main vascular bundle in the rachis. This change alternates between the two groups of main bundles and is related to the bilateral alternate arrangement of the spikelets on the rachis, so that a large amphivasal phase of the one group opposes the collateral phase of the other group. Ring-shaped tracheary inter-connections were observed mostly at the nodes. A similar system was found in the rachilla. There is a continuous uninterrupted tracheary connection between each of the florets and the rachis. A functional significance of the periodic changes observed has been suggested.

Vascular adaptations for heat conservation in the tail of Florida manatees (Trichechus manatus latirostris)

PubMed Central

Rommel, Sentiel A; Caplan, Heather

2003-01-01

Although Florida manatees (Trichechus manatus latirostris) have relatively low basal metabolic rates for aquatic mammals of their size, they maintain normal mammalian core temperatures. We describe vascular structures in the manatee tail that permit countercurrent heat exchange (CCHE) to conserve thermal energy. Approximately 1000 arteries juxtaposed to 2000 veins are found at the cranial end of the caudal vascular bundle (CVB); these numbers decrease caudally, but the 1 : 2 ratio of arteries to veins persists. Arterial walls are relatively thin when compared to those previously described in vascular countercurrent heat exchangers in cetaceans. It is assumed that CCHE in the CVB helps manatees to maintain core temperatures. Activity in warm water, however, mandates a mechanism that prevents elevated core temperatures. The tail could transfer heat to the environment if arterial blood delivered to the skin were warmer than the surrounding water; unfortunately, CCHE prevents this heat transfer. We describe deep caudal veins that provide a collateral venous return from the tail. This return, which is physically outside the CVB, reduces the venous volume within the bundle and allows arterial expansion and increased arterial supply to the skin, and thus helps prevent elevated core temperatures. PMID:12739612

Vascular adaptations for heat conservation in the tail of Florida manatees (Trichechus manatus latirostris).

PubMed

Rommel, Sentiel A; Caplan, Heather

2003-04-01

Although Florida manatees (Trichechus manatus latirostris) have relatively low basal metabolic rates for aquatic mammals of their size, they maintain normal mammalian core temperatures. We describe vascular structures in the manatee tail that permit countercurrent heat exchange (CCHE) to conserve thermal energy. Approximately 1000 arteries juxtaposed to 2000 veins are found at the cranial end of the caudal vascular bundle (CVB); these numbers decrease caudally, but the 1:2 ratio of arteries to veins persists. Arterial walls are relatively thin when compared to those previously described in vascular countercurrent heat exchangers in cetaceans. It is assumed that CCHE in the CVB helps manatees to maintain core temperatures. Activity in warm water, however, mandates a mechanism that prevents elevated core temperatures. The tail could transfer heat to the environment if arterial blood delivered to the skin were warmer than the surrounding water; unfortunately, CCHE prevents this heat transfer. We describe deep caudal veins that provide a collateral venous return from the tail. This return, which is physically outside the CVB, reduces the venous volume within the bundle and allows arterial expansion and increased arterial supply to the skin, and thus helps prevent elevated core temperatures.

Whole-Mount Adult Ear Skin Imaging Reveals Defective Neuro-Vascular Branching Morphogenesis in Obese and Type 2 Diabetic Mouse Models.

PubMed

Yamazaki, Tomoko; Li, Wenling; Yang, Ling; Li, Ping; Cao, Haiming; Motegi, Sei-Ichiro; Udey, Mark C; Bernhard, Elise; Nakamura, Takahisa; Mukouyama, Yoh-Suke

2018-01-11

Obesity and type 2 diabetes are frequently associated with peripheral neuropathy. Though there are multiple methods for diagnosis and analysis of morphological changes of peripheral nerves and blood vessels, three-dimensional high-resolution imaging is necessary to appreciate the pathogenesis with an anatomically recognizable branching morphogenesis and patterning. Here we established a novel technique for whole-mount imaging of adult mouse ear skin to visualize branching morphogenesis and patterning of peripheral nerves and blood vessels. Whole-mount immunostaining of adult mouse ear skin showed that peripheral sensory and sympathetic nerves align with large-diameter blood vessels. Diet-induced obesity (DIO) mice exhibit defective vascular smooth muscle cells (VSMCs) coverage, while there is no significant change in the amount of peripheral nerves. The leptin receptor-deficient db/db mice, a severe obese and type 2 diabetic mouse model, exhibit defective VSMC coverage and a large increase in the amount of smaller-diameter nerve bundles with myelin sheath and unmyelinated nerve fibers. Interestingly, an increase in the amount of myeloid immune cells was observed in the DIO but not db/db mouse skin. These data suggest that our whole-mount imaging method enables us to investigate the neuro-vascular and neuro-immune phenotypes in the animal models of obesity and diabetes.

Morphological changes in vascular and circulating blood cells following exposure to detergent sclerosants.

PubMed

Cooley-Andrade, O; Connor, D E; Ma, D D F; Weisel, J W; Parsi, K

2016-04-01

To investigate morphological changes in vascular and circulating blood cells following exposure to detergent sclerosants sodium tetradecyl sulfate and polidocanol. Samples of whole blood, isolated leukocytes, platelets, endothelial cells, and fibroblasts were incubated with varying concentrations of sclerosants. Whole blood smears were stained with Giemsa and examined by light and bright field microscopy. Phalloidin and Hoechst stains were used to analyze cytoplasmic and nuclear morphology by fluorescence microscopy. Endothelial cell and fibroblasts were analyzed by live cell imaging. Higher concentrations of sclerosants induced cell lysis. Morphological changes in intact cells were observed at sublytic concentrations of detergents. Low concentration sodium tetradecyl sulfate induced erythrocyte acanthocytosis and macrocytosis, while polidocanol induced Rouleaux formation and increased the population of target cells and stomatocytes. Leukocytes showed swelling, blebbing, vacuolation, and nuclear degradation following exposure to sodium tetradecyl sulfate, while polidocanol induced pseudopodia formation, chromatin condensation, and fragmentation. Platelets exhibited pseudopodia with sodium tetradecyl sulfate and a "fried egg" appearance with polidocanol. Exposure to sodium tetradecyl sulfate resulted in size shrinkage in both endothelial cell and fibroblasts, while endothelial cell developed distinct spindle morphology. Polidocanol induced cytoplasmic microfilament bundles in both endothelial cell and fibroblasts. Patchy chromatin condensation was observed following exposure of fibroblasts to either agent. Detergent sclerosants are biologically active at sublytic concentrations. The observed morphological changes are consistent with cell activation, apoptosis, and oncosis. The cellular response is concentration dependent, cell-specific, and sclerosant specific. © The Author(s) 2015.

Vascularized bone transplant chimerism mediated by vascular endothelial growth factor.

PubMed

Willems, Wouter F; Larsen, Mikko; Friedrich, Patricia F; Bishop, Allen T

2015-01-01

Vascular endothelial growth factor (VEGF) induces angiogenesis and osteogenesis in bone allotransplants. We aim to determine whether bone remodeling in VEGF-treated bone allotransplants results from repopulation with circulation-derived autogenous cells or survival of allogenic transplant-derived cells. Vascularized femoral bone transplants were transplanted from female Dark Agouti rats (DA;RT1(a) ) to male Piebald Viral Glaxo (PVG;RT1(c) ). Arteriovenous bundle implantation and short-term immunosuppression were used to maintain cellular viability. VEGF was encapsulated in biodegradable microspheres and delivered intramedullary in the experimental group (n = 22). In the control group (n = 22), no VEGF was delivered. Rats were sacrificed at 4 or 18 weeks. Laser capture microdissection of bone remodeling areas was performed at the inner and outer cortex. Sex-mismatched genes were quantified with reverse transcription-polymerase chain reaction to determine the amount of male cells to total cells, defined as the relative expression ratio (rER). At 4 weeks, rER was significantly higher at the inner cortex in VEGF-treated transplants as compared to untreated transplants (0.622 ± 0.225 vs. 0.362 ± 0.081, P = 0.043). At 4 weeks, the outer cortex in the control group had a significantly higher rER (P = 0.038), whereas in the VEGF group, the inner cortex had a higher rER (P = 0.015). Over time, in the outer cortex the rER significantly increased to 0.634 ± 0.106 at 18 weeks in VEGF-treated rats (P = 0.049). At 18 weeks, the rER was >0.5 at all cortical areas in both groups. These in vivo findings suggest a chemotactic effect of intramedullary applied VEGF on recipient-derived bone and could imply that more rapid angiogenesis of vascularized allotransplants can be established with microencapsulated VEGF. © 2014 Wiley Periodicals, Inc.

Negative hair-bundle stiffness betrays a mechanism for mechanical amplification by the hair cell.

PubMed

Martin, P; Mehta, A D; Hudspeth, A J

2000-10-24

Hearing and balance rely on the ability of hair cells in the inner ear to sense miniscule mechanical stimuli. In each cell, sound or acceleration deflects the mechanosensitive hair bundle, a tuft of rigid stereocilia protruding from the cell's apical surface. By altering the tension in gating springs linked to mechanically sensitive transduction channels, this deflection changes the channels' open probability and elicits an electrical response. To detect weak stimuli despite energy losses caused by viscous dissipation, a hair cell can use active hair-bundle movement to amplify its mechanical inputs. This amplificatory process also yields spontaneous bundle oscillations. Using a displacement-clamp system to measure the mechanical properties of individual hair bundles from the bullfrog's ear, we found that an oscillatory bundle displays negative slope stiffness at the heart of its region of mechanosensitivity. Offsetting the hair bundle's position activates an adaptation process that shifts the region of negative stiffness along the displacement axis. Modeling indicates that the interplay between negative bundle stiffness and the motor responsible for mechanical adaptation produces bundle oscillation similar to that observed. Just as the negative resistance of electrically excitable cells and of tunnel diodes can be embedded in a biasing circuit to amplify electrical signals, negative stiffness can be harnessed to amplify mechanical stimuli in the ear.

Time-course of programmed cell death during leaf senescence in Eucommia ulmoides.

PubMed

Cao, Jing; Jiang, Feng; Sodmergen; Cui, Keming

2003-02-01

Leaves of Eucommia ulmoidesOliv. harvested between April to November were examined for programmed cell death (PCD) during growth and senescence. Leaves developed in April, becoming fully expanded in late May, remaining unchanged until November when they started to dehisce. Falling leaves retained a green color. Our results showed that (1) mesophyll cells gradually reduced their nuclei from September to November, (2) positive TUNEL signals appeared on the nuclei from August, (3) ladder-like DNA fragmentation occurred in September and October, and (4) a 20-kDa Ca(2+)-dependent DNase appeared in these same months. In fallen leaves, intact mesophyll cell nuclei could not be detected, but a few cells around the vascular bundle had nuclei. Therefore, (1) programmed cell death (PCD) of leaf cells occurred in the leaves of E. ulmoides, (2) the progress of mesophyll cell PCD lasted for more than 2 months, and (3) PCD of leaf cells was asynchronous in natural senescing leaves.

WRKY13 acts in stem development in Arabidopsis thaliana.

PubMed

Li, Wei; Tian, Zhaoxia; Yu, Diqiu

2015-07-01

Stems are important for plants to grow erectly. In stems, sclerenchyma cells must develop secondary cell walls to provide plants with physical support. The secondary cell walls are mainly composed of lignin, xylan and cellulose. Deficiency of overall stem development could cause weakened stems. Here we prove that WRKY13 acts in stem development. The wrky13 mutants take on a weaker stem phenotype. The number of sclerenchyma cells, stem diameter and the number of vascular bundles were reduced in wrky13 mutants. Lignin-synthesis-related genes were repressed in wrky13 mutants. Chromatin immunoprecipitation assays proved that WRKY13 could directly bind to the promoter of NST2. Taken together, we proposed that WRKY13 affected the overall development of stem. Identification of the role of WRKY13 may help to resolve agricultural problems caused by weaker stems. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Characterization of a novel glycine-rich protein from the cell wall of maize silk tissues.

PubMed

Tao, T Y; Ouellet, T; Dadej, K; Miller, S S; Johnson, D A; Singh, J

2006-08-01

The isolation, characterization and regulation of expression of a maize silk-specific gene is described. zmgrp5 (Zea mays glycine-rich protein 5) encodes a 187 amino acid glycine-rich protein that displays developmentally regulated silk-specific expression. Northern, Western, in situ mRNA hybridization and transient gene expression analyses indicate that zmgrp5 is expressed in silk hair and in cells of the vascular bundle and pollen tube transmitting tissue elements. The protein is secreted into the extracellular matrix and is localized in the cell wall fraction mainly through interactions mediated by covalent disulphide bridges. Taken together, these results suggest that the protein may play a role in maintaining silk structure during development. This is the first documented isolation of a stigma-specific gene from maize, an important agronomic member of the Poaceae family.

Isolation of Mesophyll Cells and Bundle Sheath Cells from Digitaria sanguinalis (L.) Scop. Leaves and a Scanning Microscopy Study of the Internal Leaf Cell Morphology 1

PubMed Central

Edwards, Gerald E.; Black, Clanton C.

1971-01-01

A technique is described for the separation of mesophyll and bundle sheath cells from Digitaria sanguinalis leaves and evidence for separation is given with light and scanning electron micrographs. Gentle grinding of fully differentiated leaves in a mortar releases mesophyll cells which are isolated on nylon nets by filtration. More extensive grinding of the remaining tissue yields bundle sheath strands which are isolated by filtration with stainless steel sieves and nylon nets. Further grinding of bundle sheath strands in a tissue homogenizer releases bundle sheath cells which are collected on nylon nets. Percentage of purity derived from cell counts and yield data on a chlorophyll basis are given. The internal leaf cell morphology is presented in scanning electron micrographs and compared with light micrographs of fully-differentiated D. sanguinalis leaves. In leaves of plants which possess the C4-dicarboxylic acid cycle of photosynthesis, the relationship of leaf morphology to photosynthesis in mesophyll and bundle sheath cells is considered, and the hypothesis is presented that as atmospheric CO2 enters a leaf about 85% is fixed by the C4-dicarboxylic acid cycle in the mesophyll cells and 10 to 15% is fixed by the reductive pentose phosphate cycle in the bundle sheath cells. A technique also is given for the isolation of mesophyll cells from spinach leaves. Images PMID:16657571

Isolation of Mesophyll Cells and Bundle Sheath Cells from Digitaria sanguinalis (L.) Scop. Leaves and a Scanning Microscopy Study of the Internal Leaf Cell Morphology.

PubMed

Edwards, G E; Black, C C

1971-01-01

A technique is described for the separation of mesophyll and bundle sheath cells from Digitaria sanguinalis leaves and evidence for separation is given with light and scanning electron micrographs. Gentle grinding of fully differentiated leaves in a mortar releases mesophyll cells which are isolated on nylon nets by filtration. More extensive grinding of the remaining tissue yields bundle sheath strands which are isolated by filtration with stainless steel sieves and nylon nets. Further grinding of bundle sheath strands in a tissue homogenizer releases bundle sheath cells which are collected on nylon nets. Percentage of purity derived from cell counts and yield data on a chlorophyll basis are given.The internal leaf cell morphology is presented in scanning electron micrographs and compared with light micrographs of fully-differentiated D. sanguinalis leaves. In leaves of plants which possess the C(4)-dicarboxylic acid cycle of photosynthesis, the relationship of leaf morphology to photosynthesis in mesophyll and bundle sheath cells is considered, and the hypothesis is presented that as atmospheric CO(2) enters a leaf about 85% is fixed by the C(4)-dicarboxylic acid cycle in the mesophyll cells and 10 to 15% is fixed by the reductive pentose phosphate cycle in the bundle sheath cells.A technique also is given for the isolation of mesophyll cells from spinach leaves.

Comparative transduction mechanisms of hair cells in the bullfrog uticulus. 2: Sensitivity and response dynamics to hair bundle displacement

NASA Technical Reports Server (NTRS)

Baird, Richard A.

1994-01-01

The present study was motivated by an interest in seeing whether hair cell types in the bullfrog utriculus might differ in their voltage responses to hair bundle displacement. Particular interest was in assessing the contributions of two factors to the responses of utricular hair cells. First, interest in examining the effect of hair bundle morphology on the sensitivity of hair cells to natural stimulation was motivated by the observation that vestibular hair cells, unlike many auditory hair cells, are not free-standing but rather linked to an accessory cupular or otolithic membrane via the tip of their kinocilium. Interest also laid in examining the contribution, if any, of adaptation to the response properties of utricular hair cells. Hair cells in auditory and vibratory inner ear endorgans adapt to maintained displacements of their hair bundles, sharply limiting their low frequency sensitivity. This adaptation is mediated by a shift in the displacement-response curve (DRC) of the hair cell along the displacement axis. Observations suggest that the adaptation process occurs within the hair bundle and precedes mechanoelectric transduction. Recent observations of time-dependent changes in hair bundle stiffness are consistent with this conclusion. Adaptation would be expected to be most useful in inner ear endorgans in which hair cells are subject to large static displacements that could potentially saturate their instantaneous response and compromise their sensitivity to high frequency stimulation. The adaptation process also permits hair cells to maintain their sensory hair bundle in the most sensitive portion of their DRC. In vestibular otolith organs in which static sensitivity is desirable, any adaptation process in the hair cells may be undesirable. The rate and extent of the decline of the voltage responses was measured of utricular hair cells to step and sinusoidal hair bundle displacements. Then for similar resting potentials and response amplitudes, the voltage responses of individual hair cells were compared to both hair bundle displacement and intracellular current.

Synchrotron study of metal localization in Typha latifolia L. root sections

DOE PAGES

Qian, Yu; Jones, Keith W.; Feng, Huan; ...

2015-09-15

Understanding mechanisms that control plant root metal assimilation in soil is critical to the sustainable management of metal-contaminated land. With the assistance of the synchrotron X-ray fluorescence technique, this study investigated possible mechanisms that control the localization of Fe, Cu, Mn, Pb and Zn in the root tissues of Typha latifolia L. collected from a contaminated wetland. Metal localizations especially in the case of Fe and Pb in the dermal tissue and the vascular bundles were different. Cluster analysis was performed to divide the dermal tissue into iron-plaque-enriched dermal tissue and regular dermal tissue based on the spatial distribution ofmore » Pb and Fe. Factor analysis showed that Cu and Zn were closely correlated to each other in the dermal tissues. The association of Cu, Zn and Mn with Fe was strong in both regular dermal tissue and iron-plaque-enriched dermal tissue, while significant (p < 0.05) correlation of Fe with Pb was only observed in tissues enriched with iron plaque. In the vascular bundles, Zn, Mn and Cu showed strong association, suggesting that the localization of these three elements was controlled by a similar mechanism. Iron plaque in the peripheral dermal tissues acted as a barrier for Pb and a buffer for Zn, Cu and Mn. Furthermore, the Casparian strip regulated the transportation of metals from dermal tissues to the vascular bundles. The results suggested that the mechanisms controlling metal localization in root tissues varied with both tissue types and metals.« less

Rates of Water Loss and Uptake in Recalcitrant Fruits of Quercus Species Are Determined by Pericarp Anatomy

PubMed Central

Xia, Ke; Daws, Matthew I.; Stuppy, Wolfgang; Zhou, Zhe-Kun; Pritchard, Hugh W.

2012-01-01

Desiccation-sensitive recalcitrant seeds and fruits are killed by the loss of even moderate quantities of water. Consequently, minimizing the rate of water loss may be an important ecological factor and evolutionary driver by reducing the risk of mortality during post-dispersal dry-spells. For recalcitrant fruits of a range of Quercus species, prolonged drying times have been observed previously. However, the underlying mechanism(s) for this variation is unknown. Using nine Quercus species we investigated the major route(s) of water flow into and out of the fruits and analysed the relative importance of the different pericarp components and their anatomy on water uptake/loss. During imbibition (rehydration), the surface area of the cupule scar and the frequency and area of the vascular bundles contained therein were significantly correlated with the rates of water uptake across the scar. The vascular bundles serving the apex of the fruit were a minor contributor to overall water. Further, the rate of water uptake across the remainder of the pericarp surface was significantly correlated with the thickness of the vascularised inner layer in the pericarp. Fruits of Q. franchetii and Q. schottkyana dried most slowly and had a comparatively small scar surface area with few vascular bundles per unit area. These species inhabit drier regions than the other species studied, suggesting these anatomical features may have ecological value by reducing the risk of desiccation stress. However, this remains to be tested in the field. PMID:23071795

Analysis of the Proteome of Hair-Cell Stereocilia by Mass Spectrometry

PubMed Central

Krey, Jocelyn F.; Wilmarth, Philip A.; David, Larry L.; Barr-Gillespie, Peter G.

2017-01-01

Characterization of proteins that mediate mechanotransduction by hair cells, the sensory cells of the inner ear, is hampered by the scarcity of these cells and their sensory organelle, the hair bundle. Mass spectrometry, with its high sensitivity and identification precision, is the ideal method for determining which proteins are present in bundles and what proteins they interact with. We describe here the isolation of mouse hair bundles, as well as preparation of bundle-protein samples for mass spectrometry. We also describe protocols for data-dependent (shotgun) and parallel-reaction-monitoring (targeted) mass spectrometry that allow us to identify and quantify proteins of the hair bundle. These sensitive methods are particularly useful for comparing proteomes of wild-type and mice with deafness mutations affecting hair-bundle proteins. (120 words; maximum 250) PMID:28109437

Hair bundles of cochlear outer hair cells are shaped to minimize their fluid-dynamic resistance.

PubMed

Ciganović, Nikola; Wolde-Kidan, Amanuel; Reichenbach, Tobias

2017-06-15

The mammalian sense of hearing relies on two types of sensory cells: inner hair cells transmit the auditory stimulus to the brain, while outer hair cells mechanically modulate the stimulus through active feedback. Stimulation of a hair cell is mediated by displacements of its mechanosensitive hair bundle which protrudes from the apical surface of the cell into a narrow fluid-filled space between reticular lamina and tectorial membrane. While hair bundles of inner hair cells are of linear shape, those of outer hair cells exhibit a distinctive V-shape. The biophysical rationale behind this morphology, however, remains unknown. Here we use analytical and computational methods to study the fluid flow across rows of differently shaped hair bundles. We find that rows of V-shaped hair bundles have a considerably reduced resistance to crossflow, and that the biologically observed shapes of hair bundles of outer hair cells are near-optimal in this regard. This observation accords with the function of outer hair cells and lends support to the recent hypothesis that inner hair cells are stimulated by a net flow, in addition to the well-established shear flow that arises from shearing between the reticular lamina and the tectorial membrane.

Biomechanics and functional morphology of a climbing monocot

PubMed Central

Hesse, Linnea; Wagner, Sarah T.; Neinhuis, Christoph

2016-01-01

Plants with a climbing growth habit possess unique biomechanical properties arising from adaptations to changing loading conditions connected with close attachment to mechanical supports. In monocot climbers, mechanical adaptation is restricted by the absence of a bifacial vascular cambium. Flagellaria indica was used to investigate the mechanical properties and adaptations of a monocot climber that, uniquely, attaches to the surrounding vegetation via leaf tendrils. Biomechanical methods such as three-point bending and torsion tests were used together with anatomical studies on tissue development, modification and distribution. In general, the torsional modulus was lower than the bending modulus; hence, torsional stiffness was less than flexural stiffness. Basal parts of mature stems showed the greatest stiffness while that of more apical stem segments levelled off. Mechanical properties were modulated via tissue maturation processes mainly affecting the peripheral region of the stem. Peripheral vascular bundles showed a reduction in the amount of conducting tissue while the proportion and density of the bundle sheath increased. Furthermore, adjacent bundle sheaths merged resulting in a dense ring of fibrous tissue. Although F. indica lacks secondary cambial growth, the climbing habit is facilitated by a complex interaction of tissue maturation and attachment. PMID:26819259

[Difference of root anatomy characteristics and its effect on DEHP accumulation in two genotypes of Brassica parachinensis].

PubMed

Zeng, Qiao-yun; Mo, Ce-hui; Wen, Rong-lian; Cai, Quan-ying

2010-08-01

Two genotypes of Brassica parachinensis, DEHP high-accumulation of Youqing-60 and low-accumulation of Teqing-60, were grown in hydroponic systems contaminated with DEHP (20 and 50 mg x L(-1)). Anatomy of roots was measured, and their effects on uptake of DEHP in roots and shoots were discussed. The results showed that roots anatomy of two genotypes of Brassica parachinensis and their responds to DEHP pollution were significantly different. DEHP contents in roots and shoots of Youqing-60 were mainly affected by the thickness of cambium in taproot and the diameter of vascular bundle, the coefficients on DEHP of roots and shoots were 0.900 and 0.809, respectively. DEHP contents of Teqing-60 were mainly affected by the thickness of cambium in taproot and cortex in fibre root in roots, which the coefficient was 0.757, and were mainly affected by the thickness of cambium in taproot in shoots, which the coefficient was 0.856. The wood ray cells in roots of Youqing-60 were rectangular shape and arranged orderly. The thickness of cork layer in taproot and cortex in fibre root of Youqing-60 were lower and the quantity of trachea and diameter of vascular bundle and trachea in fibre root of Yonqing-60 were higher than that of Teqing-60, which indicated that DEHP in soil solution and adsorbed on root were easier penetrated into xylem and transported in Youqing-60 than in Teqing-60.

Steady-state stiffness of utricular hair cells depends on macular location and hair bundle structure.

PubMed

Spoon, Corrie; Moravec, W J; Rowe, M H; Grant, J W; Peterson, E H

2011-12-01

Spatial and temporal properties of head movement are encoded by vestibular hair cells in the inner ear. One of the most striking features of these receptors is the orderly structural variation in their mechanoreceptive hair bundles, but the functional significance of this diversity is poorly understood. We tested the hypothesis that hair bundle structure is a significant contributor to hair bundle mechanics by comparing structure and steady-state stiffness of 73 hair bundles at varying locations on the utricular macula. Our first major finding is that stiffness of utricular hair bundles varies systematically with macular locus. Stiffness values are highest in the striola, near the line of hair bundle polarity reversal, and decline exponentially toward the medial extrastriola. Striolar bundles are significantly more stiff than those in medial (median: 8.9 μN/m) and lateral (2.0 μN/m) extrastriolae. Within the striola, bundle stiffness is greatest in zone 2 (106.4 μN/m), a band of type II hair cells, and significantly less in zone 3 (30.6 μN/m), which contains the only type I hair cells in the macula. Bathing bundles in media that break interciliary links produced changes in bundle stiffness with predictable time course and magnitude, suggesting that links were intact in our standard media and contributed normally to bundle stiffness during measurements. Our second major finding is that bundle structure is a significant predictor of steady-state stiffness: the heights of kinocilia and the tallest stereocilia are the most important determinants of bundle stiffness. Our results suggest 1) a functional interpretation of bundle height variability in vertebrate vestibular organs, 2) a role for the striola in detecting onset of head movement, and 3) the hypothesis that differences in bundle stiffness contribute to diversity in afferent response dynamics.

Steady-state stiffness of utricular hair cells depends on macular location and hair bundle structure

PubMed Central

Spoon, Corrie; Moravec, W. J.; Rowe, M. H.; Grant, J. W.

2011-01-01

Spatial and temporal properties of head movement are encoded by vestibular hair cells in the inner ear. One of the most striking features of these receptors is the orderly structural variation in their mechanoreceptive hair bundles, but the functional significance of this diversity is poorly understood. We tested the hypothesis that hair bundle structure is a significant contributor to hair bundle mechanics by comparing structure and steady-state stiffness of 73 hair bundles at varying locations on the utricular macula. Our first major finding is that stiffness of utricular hair bundles varies systematically with macular locus. Stiffness values are highest in the striola, near the line of hair bundle polarity reversal, and decline exponentially toward the medial extrastriola. Striolar bundles are significantly more stiff than those in medial (median: 8.9 μN/m) and lateral (2.0 μN/m) extrastriolae. Within the striola, bundle stiffness is greatest in zone 2 (106.4 μN/m), a band of type II hair cells, and significantly less in zone 3 (30.6 μN/m), which contains the only type I hair cells in the macula. Bathing bundles in media that break interciliary links produced changes in bundle stiffness with predictable time course and magnitude, suggesting that links were intact in our standard media and contributed normally to bundle stiffness during measurements. Our second major finding is that bundle structure is a significant predictor of steady-state stiffness: the heights of kinocilia and the tallest stereocilia are the most important determinants of bundle stiffness. Our results suggest 1) a functional interpretation of bundle height variability in vertebrate vestibular organs, 2) a role for the striola in detecting onset of head movement, and 3) the hypothesis that differences in bundle stiffness contribute to diversity in afferent response dynamics. PMID:21918003

Multiple pass gas absorption cell utilizing a spherical mirror opposite one or more pair of obliquely disposed flat mirrors

NASA Technical Reports Server (NTRS)

Pearson, Richard (Inventor); Lynch, Dana H. (Inventor); Gunter, William D. (Inventor)

1995-01-01

A method and apparatus for passing light bundles through a multiple pass sampling cell is disclosed. The multiple pass sampling cell includes a sampling chamber having first and second ends positioned along a longitudinal axis of the sampling cell. The sampling cell further includes an entrance opening, located adjacent the first end of the sampling cell at a first azimuthal angular position. The entrance opening permits a light bundle to pass into the sampling cell. The sampling cell also includes an exit opening at a second azimuthal angular position. The light exit permits a light bundle to pass out of the sampling cell after the light bundle has followed a predetermined path.

Verticillium Infection Triggers VASCULAR-RELATED NAC DOMAIN7–Dependent de Novo Xylem Formation and Enhances Drought Tolerance in Arabidopsis[W

PubMed Central

Reusche, Michael; Thole, Karin; Janz, Dennis; Truskina, Jekaterina; Rindfleisch, Sören; Drübert, Christine; Polle, Andrea; Lipka, Volker; Teichmann, Thomas

2012-01-01

The soilborne fungal plant pathogen Verticillium longisporum invades the roots of its Brassicaceae hosts and proliferates in the plant vascular system. Typical aboveground symptoms of Verticillium infection on Brassica napus and Arabidopsis thaliana are stunted growth, vein clearing, and leaf chloroses. Here, we provide evidence that vein clearing is caused by pathogen-induced transdifferentiation of chloroplast-containing bundle sheath cells to functional xylem elements. In addition, our findings suggest that reinitiation of cambial activity and transdifferentiation of xylem parenchyma cells results in xylem hyperplasia within the vasculature of Arabidopsis leaves, hypocotyls, and roots. The observed de novo xylem formation correlates with Verticillium-induced expression of the VASCULAR-RELATED NAC DOMAIN (VND) transcription factor gene VND7. Transgenic Arabidopsis plants expressing the chimeric repressor VND7-SRDX under control of a Verticillium infection-responsive promoter exhibit reduced de novo xylem formation. Interestingly, infected Arabidopsis wild-type plants show higher drought stress tolerance compared with noninfected plants, whereas this effect is attenuated by suppression of VND7 activity. Together, our results suggest that V. longisporum triggers a tissue-specific developmental plant program that compensates for compromised water transport and enhances the water storage capacity of infected Brassicaceae host plants. In conclusion, we provide evidence that this natural plant–fungus pathosystem has conditionally mutualistic features. PMID:23023171

Pseudoaneurysm of the articular branch of the descending genicular artery following double-bundle anterior cruciate ligament reconstruction.

PubMed

Tsubosaka, Masanori; Matsushita, Takehiko; Kuroda, Ryosuke; Matsumoto, Tomoyuki; Kurosaka, Masahiro

2017-09-01

This report describes a case of a pseudoaneurysm of the articular branch of the descending genicular artery following double-bundle anterior cruciate ligament (ACL) reconstruction. An 18-year-old male received double-bundle ACL reconstruction. During ACL reconstruction, a far anteromedial portal was created for femoral tunnel drilling. The patient presented with pulsatile swelling on the medial side of the knee on the second post-operative day. The pseudoaneurysm was diagnosed using contrast computed tomography and Doppler ultrasonography and was subsequently treated by embolization with a microcatheter. Although a vascular injury is a very rare complication of knee arthroscopy, it should be considered a possibility in patients who undergo such procedures. V.

The influence of leaf anatomy on the internal light environment and photosynthetic electron transport rate: exploration with a new leaf ray tracing model

PubMed Central

Xiao, Yi; Tholen, Danny; Zhu, Xin-Guang

2016-01-01

Leaf photosynthesis is determined by biochemical properties and anatomical features. Here we developed a three-dimensional leaf model that can be used to evaluate the internal light environment of a leaf and its implications for whole-leaf electron transport rates (J). This model includes (i) the basic components of a leaf, such as the epidermis, palisade and spongy tissues, as well as the physical dimensions and arrangements of cell walls, vacuoles and chloroplasts; and (ii) an efficient forward ray-tracing algorithm, predicting the internal light environment for light of wavelengths between 400 and 2500nm. We studied the influence of leaf anatomy and ambient light on internal light conditions and J. The results show that (i) different chloroplasts can experience drastically different light conditions, even when they are located at the same distance from the leaf surface; (ii) bundle sheath extensions, which are strips of parenchyma, collenchyma or sclerenchyma cells connecting the vascular bundles with the epidermis, can influence photosynthetic light-use efficiency of leaves; and (iii) chloroplast positioning can also influence the light-use efficiency of leaves. Mechanisms underlying leaf internal light heterogeneity and implications of the heterogeneity for photoprotection and for the convexity of the light response curves are discussed. PMID:27702991

Synchronization of Spontaneous Active Motility of Hair Cell Bundles

PubMed Central

Zhang, Tracy-Ying; Ji, Seung; Bozovic, Dolores

2015-01-01

Hair cells of the inner ear exhibit an active process, believed to be crucial for achieving the sensitivity of auditory and vestibular detection. One of the manifestations of the active process is the occurrence of spontaneous hair bundle oscillations in vitro. Hair bundles are coupled by overlying membranes in vivo; hence, explaining the potential role of innate bundle motility in the generation of otoacoustic emissions requires an understanding of the effects of coupling on the active bundle dynamics. We used microbeads to connect small groups of hair cell bundles, using in vitro preparations that maintain their innate oscillations. Our experiments demonstrate robust synchronization of spontaneous oscillations, with either 1:1 or multi-mode phase-locking. The frequency of synchronized oscillation was found to be near the mean of the innate frequencies of individual bundles. Coupling also led to an improved regularity of entrained oscillations, demonstrated by an increase in the quality factor. PMID:26540409

Stimulation of hair cells with ultraviolet light

NASA Astrophysics Data System (ADS)

Azimzadeh, Julien B.; Fabella, Brian A.; Hudspeth, A. J.

2018-05-01

Hair bundles are specialized organelles that transduce mechanical inputs into electrical outputs. To activate hair cells, physiologists have resorted to mechanical methods of hair-bundle stimulation. Here we describe a new method of hair-bundle stimulation, irradiation with ultraviolet light. A hair bundle illuminated by ultraviolet light rapidly moves towards its tall edge, a motion typically associated with excitatory stimulation. The motion disappears upon tip-link rupture and is associated with the opening of mechanotransduction channels. Hair bundles can be induced to move sinusoidally with oscillatory modulation of the stimulation power. We discuss the implications of ultraviolet stimulation as a novel hair-bundle stimulus.

Uptake, sequestration and tolerance of cadmium at cellular levels in the hyperaccumulator plant species Sedum alfredii

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tian, Shengke; Xie, Ruohan; Wang, Haixin

Sedum alfredii is one of a few plant species known to hyperaccumulate cadmium (Cd). Uptake, localization, and tolerance of Cd at cellular levels in shoots were compared in hyperaccumulating (HE) and non-hyperaccumulating (NHE) ecotypes of Sedum alfredii. X-ray fluorescence images of Cd in stems and leaves showed only a slight Cd signal restricted within vascular bundles in the NHEs, while enhanced localization of Cd, with significant tissue- and age-dependent variations, was detected in HEs. In contrast to the vascular-enriched Cd in young stems, parenchyma cells in leaf mesophyll, stem pith and cortex tissues served as terminal storage sites for Cdmore » sequestration in HEs. Kinetics of Cd transport into individual leaf protoplasts of the two ecotypes showed little difference in Cd accumulation. However, far more efficient storage of Cd in vacuoles was apparent in HEs. Subsequent analysis of cell viability and hydrogen peroxide levels suggested that HE protoplasts exhibited higher resistance to Cd than those of NHE protoplasts. These results suggest that efficient sequestration into vacuoles, as opposed to rapid transport into parenchyma cells, is a pivotal process in Cd accumulation and homeostasis in shoots of HE S. alfredii. This is in addition to its efficient root-to-shoot translocation of Cd.« less

Synchrotron study of metal localization in Typha latifolia  L. root sections

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qian, Yu; Feng, Huan; Gallagher, Frank J.

2015-10-13

Understanding mechanisms that control plant root metal assimilation in soil is critical to the sustainable management of metal-contaminated land. With the assistance of the synchrotron X-ray fluorescence technique, this study investigated possible mechanisms that control the localization of Fe, Cu, Mn, Pb and Zn in the root tissues ofTypha latifolia L. collected from a contaminated wetland. Metal localizations especially in the case of Fe and Pb in the dermal tissue and the vascular bundles were different. Cluster analysis was performed to divide the dermal tissue into iron-plaque-enriched dermal tissue and regular dermal tissue based on the spatial distribution of Pb andmore » Fe. Factor analysis showed that Cu and Zn were closely correlated to each other in the dermal tissues. The association of Cu, Zn and Mn with Fe was strong in both regular dermal tissue and iron-plaque-enriched dermal tissue, while significant (p< 0.05) correlation of Fe with Pb was only observed in tissues enriched with iron plaque. In the vascular bundles, Zn, Mn and Cu showed strong association, suggesting that the localization of these three elements was controlled by a similar mechanism. Iron plaque in the peripheral dermal tissues acted as a barrier for Pb and a buffer for Zn, Cu and Mn. The Casparian strip regulated the transportation of metals from dermal tissues to the vascular bundles. The results suggested that the mechanisms controlling metal localization in root tissues varied with both tissue types and metals.« less

Structural and immunohistochemical changes in the hepatic vascular system in compensated and decompensated stenosis of the pulmonary trunk.

PubMed

Novikov, Yu V; Shormanov, S V; Kulikov, S V

2012-01-01

Modeling of pulmonary trunk stenosis leads to an increase in hepatic vascular resistance because of veno-arterial and veno-venous reactions. During the compensation phase, bundles of intimal musculature and myoelastic sphincters appear in the arteries, while in the efferent veins hypertrophy of the muscle rolls is observed. The decompensation phase of stenosis is characterized by relaxation of hepatic vascular walls, reduction of the number of arteries with intimal muscles and sphincter structures, and atrophy of muscle rolls in hepatic veins. Sclerotic changes develop in the vascular bed. Failure of the compensatory reactions results in development of chronic hepatic venous plethora with typical morphological manifestations.

From cell differentiation to cell collectives: Bacillus subtilis uses division of labor to migrate.

PubMed

van Gestel, Jordi; Vlamakis, Hera; Kolter, Roberto

2015-04-01

The organization of cells, emerging from cell-cell interactions, can give rise to collective properties. These properties are adaptive when together cells can face environmental challenges that they separately cannot. One particular challenge that is important for microorganisms is migration. In this study, we show how flagellum-independent migration is driven by the division of labor of two cell types that appear during Bacillus subtilis sliding motility. Cell collectives organize themselves into bundles (called "van Gogh bundles") of tightly aligned cell chains that form filamentous loops at the colony edge. We show, by time-course microscopy, that these loops migrate by pushing themselves away from the colony. The formation of van Gogh bundles depends critically on the synergistic interaction of surfactin-producing and matrix-producing cells. We propose that surfactin-producing cells reduce the friction between cells and their substrate, thereby facilitating matrix-producing cells to form bundles. The folding properties of these bundles determine the rate of colony expansion. Our study illustrates how the simple organization of cells within a community can yield a strong ecological advantage. This is a key factor underlying the diverse origins of multicellularity.

Microtubule bundling plays a role in ethylene-mediated cortical microtubule reorientation in etiolated Arabidopsis hypocotyls.

PubMed

Ma, Qianqian; Sun, Jingbo; Mao, Tonglin

2016-05-15

The gaseous hormone ethylene is known to regulate plant growth under etiolated conditions (the 'triple response'). Although organization of cortical microtubules is essential for cell elongation, the underlying mechanisms that regulate microtubule organization by hormone signaling, including ethylene, are ambiguous. In the present study, we demonstrate that ethylene signaling participates in regulation of cortical microtubule reorientation. In particular, regulation of microtubule bundling is important for this process in etiolated hypocotyls. Time-lapse analysis indicated that selective stabilization of microtubule-bundling structures formed in various arrays is related to ethylene-mediated microtubule orientation. Bundling events and bundle growth lifetimes were significantly increased in oblique and longitudinal arrays, but decreased in transverse arrays in wild-type cells in response to ethylene. However, the effects of ethylene on microtubule bundling were partially suppressed in a microtubule-bundling protein WDL5 knockout mutant (wdl5-1). This study suggests that modulation of microtubule bundles that have formed in certain orientations plays a role in reorienting microtubule arrays in response to ethylene-mediated etiolated hypocotyl cell elongation. © 2016. Published by The Company of Biologists Ltd.

Ulnar nerve sonography in leprosy neuropathy.

PubMed

Wang, Zhu; Liu, Da-Yue; Lei, Yang-Yang; Yang, Zheng; Wang, Wei

2016-01-01

A 23-year-old woman presented with a half-year history of right forearm sensory and motor dysfunction. Ultrasound imaging revealed definite thickening of the right ulnar nerve trunk and inner epineurium, along with heterogeneous hypoechogenicity and unclear nerve fiber bundle. Color Doppler exhibited a rich blood supply, which was clearly different from the normal ulnar nerve presentation with a scarce blood supply. The patient subsequently underwent needle aspiration of the right ulnar nerve, and histopathological examination confirmed that granulomatous nodules had formed with a large number of infiltrating lymphocytes and a plurality of epithelioid cells in the fibrous connective tissues, with visible atypical foam cells and proliferous vascularization, consistent with leprosy. Our report will familiarize readers with the characteristic sonographic features of the ulnar nerve in leprosy, particularly because of the decreasing incidence of leprosy in recent years.

Probabilistic visual and electromagnetic data fusion for robust drift-free sequential mosaicking: application to fetoscopy

PubMed Central

Tella-Amo, Marcel; Peter, Loic; Shakir, Dzhoshkun I.; Deprest, Jan; Iglesias, Juan Eugenio; Ourselin, Sebastien

2018-01-01

Abstract. The most effective treatment for twin-to-twin transfusion syndrome is laser photocoagulation of the shared vascular anastomoses in the placenta. Vascular connections are extremely challenging to locate due to their caliber and the reduced field-of-view of the fetoscope. Therefore, mosaicking techniques are beneficial to expand the scene, facilitate navigation, and allow vessel photocoagulation decision-making. Local vision-based mosaicking algorithms inherently drift over time due to the use of pairwise transformations. We propose the use of an electromagnetic tracker (EMT) sensor mounted at the tip of the fetoscope to obtain camera pose measurements, which we incorporate into a probabilistic framework with frame-to-frame visual information to achieve globally consistent sequential mosaics. We parametrize the problem in terms of plane and camera poses constrained by EMT measurements to enforce global consistency while leveraging pairwise image relationships in a sequential fashion through the use of local bundle adjustment. We show that our approach is drift-free and performs similarly to state-of-the-art global alignment techniques like bundle adjustment albeit with much less computational burden. Additionally, we propose a version of bundle adjustment that uses EMT information. We demonstrate the robustness to EMT noise and loss of visual information and evaluate mosaics for synthetic, phantom-based and ex vivo datasets. PMID:29487889

Heterotopic bone formation in the musculus latissimus dorsi of sheep using β-tricalcium phosphate scaffolds: evaluation of an extended prefabrication time on bone formation and matrix degeneration.

PubMed

Spalthoff, S; Jehn, P; Zimmerer, R; Möllmann, U; Gellrich, N-C; Kokemueller, H

2015-06-01

We previously generated viable heterotopic bone in living animals and found that 3 months of intrinsic vascularization improved bone formation and matrix degeneration. In this study, we varied the pre-vascularization time to determine its effects on the kinetics of bone formation and ceramic degradation. Two 25-mm-long cylindrical β-tricalcium phosphate scaffolds were filled intraoperatively with autogenous iliac crest bone marrow and implanted in the latissimus dorsi muscle in six sheep. To examine the effect of axial perfusion, one scaffold was surgically implanted with (group C) or without (group D) a central vascular bundle. All animals were sacrificed 6 months postoperatively and histomorphometric measurements were compared to previous results. All implanted scaffolds exhibited ectopic bone growth. However, bone growth was not significantly different between the 3-month (group A, 0.191±0.097 vs. group C, 0.237±0.075; P=0.345) and 6-month (group B, 0.303±0.105 vs. group D, 0.365±0.258; P=0.549) pre-vascularization durations, regardless of vessel supply; early differences between surgically and extrinsically vascularized constructs disappeared after 6 months. Here, we describe a reliable procedure for generating ectopic bone in vivo. A 3-month pre-vascularization duration appears sufficient and ceramic degradation proceeds in accordance with bone generation, supporting the hypothesis of cell-mediated resorption. Copyright © 2014 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Daple coordinates organ-wide and cell-intrinsic polarity to pattern inner-ear hair bundles

PubMed Central

Siletti, Kimberly; Hudspeth, A. J.

2017-01-01

The establishment of planar polarization by mammalian cells necessitates the integration of diverse signaling pathways. In the inner ear, at least two systems regulate the planar polarity of sensory hair bundles. The core planar cell polarity (PCP) proteins coordinate the orientations of hair cells across the epithelial plane. The cell-intrinsic patterning of hair bundles is implemented independently by the G protein complex classically known for orienting the mitotic spindle. Although the primary cilium also participates in each of these pathways, its role and the integration of the two systems are poorly understood. We show that Dishevelled-associating protein with a high frequency of leucine residues (Daple) interacts with PCP and cell-intrinsic signals. Regulated by the cell-intrinsic pathway, Daple is required to maintain the polarized distribution of the core PCP protein Dishevelled and to position the primary cilium at the abneural edge of the apical surface. Our results suggest that the primary cilium or an associated structure influences the domain of cell-intrinsic signals that shape the hair bundle. Daple is therefore essential to orient and pattern sensory hair bundles. PMID:29229865

Dimerization and actin-bundling properties of villin and its role in the assembly of epithelial cell brush borders.

PubMed

George, Sudeep P; Wang, Yaohong; Mathew, Sijo; Srinivasan, Kamalakkannan; Khurana, Seema

2007-09-07

Villin is a major actin-bundling protein in the brush border of epithelial cells. In this study we demonstrate for the first time that villin can bundle actin filaments using a single F-actin binding site, because it has the ability to self-associate. Using fluorescence resonance energy transfer, we demonstrate villin self-association in living cells in microvilli and in growth factor-stimulated cells in membrane ruffles and lamellipodia. Using sucrose density gradient, size-exclusion chromatography, and matrix-assisted laser desorption ionization time-of-flight, the majority of villin was identified as a monomer or dimer. Villin dimers were also identified in Caco-2 cells, which endogenously express villin and Madin-Darby canine kidney cells that ectopically express villin. Using truncation mutants of villin, site-directed mutagenesis, and fluorescence resonance energy transfer, an amino-terminal dimerization site was identified that regulated villin self-association in parallel conformation as well as actin bundling by villin. This detailed analysis describes for the first time microvillus assembly by villin, redefines the actin-bundling function of villin, and provides a molecular mechanism for actin bundling by villin, which could have wider implications for other actin cross-linking proteins that share a villin-like headpiece domain. Our study also provides a molecular basis to separate the morphologically distinct actin-severing and actin-bundling properties of villin.

Macroautophagy and microautophagy in relation to vacuole formation in mesophyll cells of Dendrobium tepals.

PubMed

van Doorn, Wouter G; Kirasak, Kanjana; Ketsa, Saichol

2015-04-01

Prior to flower opening, mesophyll cells at the vascular bundles of Dendrobium tepals showed a large increase in vacuolar volume, partially at the expense of the cytoplasm. Electron micrographs indicated that this increase in vacuolar volume was mainly due to vacuole fusion. Macroautophagous structures typical of plant cells were observed. Only a small part of the decrease in cytoplasmic volume seemed due to macroautophagy. The vacuoles contained vesicles of various types, including multilamellar bodies. It was not clear if these vacuolar inclusions were due to macroautophagy or microautophagy. Only a single structure was observed of a protruding vacuole, indicating microautophagy. It is concluded that macroautophagy occurs in these cells but its role in vacuole formation seems small, while a possible role of microautophagy in vacuole formation might be hypothesized. Careful labeling of organelle membranes seems required to advance our insight in plant macro- and microautophagy and their roles in vacuole formation. Copyright © 2015 Elsevier GmbH. All rights reserved.

Structural and metabolic transitions of C4 leaf development and differentiation defined by microscopy and quantitative proteomics in maize.

PubMed

Majeran, Wojciech; Friso, Giulia; Ponnala, Lalit; Connolly, Brian; Huang, Mingshu; Reidel, Edwin; Zhang, Cankui; Asakura, Yukari; Bhuiyan, Nazmul H; Sun, Qi; Turgeon, Robert; van Wijk, Klaas J

2010-11-01

C(4) grasses, such as maize (Zea mays), have high photosynthetic efficiency through combined biochemical and structural adaptations. C(4) photosynthesis is established along the developmental axis of the leaf blade, leading from an undifferentiated leaf base just above the ligule into highly specialized mesophyll cells (MCs) and bundle sheath cells (BSCs) at the tip. To resolve the kinetics of maize leaf development and C(4) differentiation and to obtain a systems-level understanding of maize leaf formation, the accumulation profiles of proteomes of the leaf and the isolated BSCs with their vascular bundle along the developmental gradient were determined using large-scale mass spectrometry. This was complemented by extensive qualitative and quantitative microscopy analysis of structural features (e.g., Kranz anatomy, plasmodesmata, cell wall, and organelles). More than 4300 proteins were identified and functionally annotated. Developmental protein accumulation profiles and hierarchical cluster analysis then determined the kinetics of organelle biogenesis, formation of cellular structures, metabolism, and coexpression patterns. Two main expression clusters were observed, each divided in subclusters, suggesting that a limited number of developmental regulatory networks organize concerted protein accumulation along the leaf gradient. The coexpression with BSC and MC markers provided strong candidates for further analysis of C(4) specialization, in particular transporters and biogenesis factors. Based on the integrated information, we describe five developmental transitions that provide a conceptual and practical template for further analysis. An online protein expression viewer is provided through the Plant Proteome Database.

Differences in Stylet Sheath Occurrence and the Fibrous Ring (Sclerenchyma) between xCitroncirus Plants Relatively Resistant or Susceptible to Adults of the Asian Citrus Psyllid Diaphorina citri (Hemiptera: Liviidae)

PubMed Central

Ammar, El-Desouky; Richardson, Matthew L.; Abdo, Zaid; Hall, David G.; Shatters, Robert G.

2014-01-01

The Asian citrus psyllid (ACP, Diaphorina citri, Hemiptera: Liviidae), is the principal vector of the phloem-limited bacteria strongly associated with huanglongbing (HLB), the world’s most serious disease of citrus. Host plant resistance may provide an environmentally safe and sustainable method of controlling ACP and/or HLB. Two xCitroncirus accessions (hybrids of Poncirus trifoliata and Citrus spp.), that are relatively resistant (UN-3881) or relatively susceptible (Troyer-1459) to ACP adults with regard to adult longevity, were compared in relation to ACP feeding behavior and some structural features of the leaf midrib. The settling (putative feeding/probing) sites of ACP adults on various parts of the leaf were not influenced primarily by plant accession. However, fewer ACP stylet sheaths were found in the midrib and fewer stylet sheath termini reached the vascular bundle (phloem and/or xylem) in UN-3881 compared to Troyer-1459 plants. Furthermore, in midribs of UN-3881 leaves the fibrous ring (sclerenchyma) around the phloem was significantly wider (thicker) compared to that in midribs of Troyer-1459 leaves. Our data indicate that feeding and/or probing by ACP adults into the vascular bundle is less frequent in the more resistant (UN-3881) than in the more susceptible (Troyer-1459) accessions. Our results also suggest that the thickness of the fibrous ring may be a barrier to stylet penetration into the vascular bundle, which is important for successful ACP feeding on the phloem and for transmitting HLB-associated bacteria. These results may help in the development of citrus plants resistant to ACP, which in turn could halt or slow the spread of the HLB-associated bacteria by this vector. PMID:25343712

The Actions of Calcium on Hair Bundle Mechanics in Mammalian Cochlear Hair Cells

PubMed Central

Beurg, Maryline; Nam, Jong-Hoon; Crawford, Andrew; Fettiplace, Robert

2008-01-01

Sound stimuli excite cochlear hair cells by vibration of each hair bundle, which opens mechanotransducer (MT) channels. We have measured hair-bundle mechanics in isolated rat cochleas by stimulation with flexible glass fibers and simultaneous recording of the MT current. Both inner and outer hair-cell bundles exhibited force-displacement relationships with a nonlinearity that reflects a time-dependent reduction in stiffness. The nonlinearity was abolished, and hair-bundle stiffness increased, by maneuvers that diminished calcium influx through the MT channels: lowering extracellular calcium, blocking the MT current with dihydrostreptomycin, or depolarizing to positive potentials. To simulate the effects of Ca2+, we constructed a finite-element model of the outer hair cell bundle that incorporates the gating-spring hypothesis for MT channel activation. Four calcium ions were assumed to bind to the MT channel, making it harder to open, and, in addition, Ca2+ was posited to cause either a channel release or a decrease in the gating-spring stiffness. Both mechanisms produced Ca2+ effects on adaptation and bundle mechanics comparable to those measured experimentally. We suggest that fast adaptation and force generation by the hair bundle may stem from the action of Ca2+ on the channel complex and do not necessarily require the direct involvement of a myosin motor. The significance of these results for cochlear transduction and amplification are discussed. PMID:18178649

Induction of human umbilical cord mesenchymal stem cells into tissue-forming cells in a murine model: implications for pelvic floor reconstruction.

PubMed

Ding, Jing; Han, Qin; Deng, Mou; Song, Xiao-Chen; Chen, Chun; Ai, Fang-Fang; Zhu, Lan; Zhao, Robert Chun-Hua

2018-06-01

HUMSCs were isolated, differentiated and characterized in vitro. Both HUMSCs and smooth muscle cells differentiated from HUMSCs were used to fabricate tissue-engineered fascia equivalents. Forty-eight mature female Sprague Dawley rats were randomly assigned to four groups: group A (GynemeshTMPS, n = 12), group B (GynemeshTMPS + HUMSCs; n = 12), group C (GynemeshTMPS + smooth muscle cells differentiated from HUMSCs; n = 12) and group D (GynemeshTMPS + HUMSCs + smooth muscle cells differentiated from HUMSCs; n = 12). The posterior vaginal wall was incised from the introitus and the mesh was then implanted. Three implants of each type were tested at 1, 4, 8 and 12 weeks. Fibrotic remodeling, inflammation, vascularization and tissue regeneration were histologically assessed. The levels of type I and type III collagen were determined. There was no difference in fibrotic remodeling between cell-seeded and unseeded meshes at any time (p > 0.05). At 12 weeks, there did not appear to be fewer inflammatory cells around the filament bundles in the mesh with cells compared with the mesh alone (P > 0.05). Group D showed a trend toward better vascularization at 12 weeks compared with group A (P < 0.05). Twelve weeks after implantation, a thin layer of new tissue growth covered the unseeded scaffold and a thicker layer covered the cell-seeded scaffold (P < 0.05). No significant difference in the ratio of collagen type I/III could be detected among the different groups after 12 weeks (P > 0.05). HUMSCs with differentiated smooth muscle cells might have a potential role in fascia tissue engineering to repair POP in the future.

The influence of leaf anatomy on the internal light environment and photosynthetic electron transport rate: exploration with a new leaf ray tracing model.

PubMed

Xiao, Yi; Tholen, Danny; Zhu, Xin-Guang

2016-11-01

Leaf photosynthesis is determined by biochemical properties and anatomical features. Here we developed a three-dimensional leaf model that can be used to evaluate the internal light environment of a leaf and its implications for whole-leaf electron transport rates (J). This model includes (i) the basic components of a leaf, such as the epidermis, palisade and spongy tissues, as well as the physical dimensions and arrangements of cell walls, vacuoles and chloroplasts; and (ii) an efficient forward ray-tracing algorithm, predicting the internal light environment for light of wavelengths between 400 and 2500nm. We studied the influence of leaf anatomy and ambient light on internal light conditions and J The results show that (i) different chloroplasts can experience drastically different light conditions, even when they are located at the same distance from the leaf surface; (ii) bundle sheath extensions, which are strips of parenchyma, collenchyma or sclerenchyma cells connecting the vascular bundles with the epidermis, can influence photosynthetic light-use efficiency of leaves; and (iii) chloroplast positioning can also influence the light-use efficiency of leaves. Mechanisms underlying leaf internal light heterogeneity and implications of the heterogeneity for photoprotection and for the convexity of the light response curves are discussed. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Defining the Diverse Cell Populations Contributing to Lignification in Arabidopsis Stems.

PubMed

Smith, Rebecca A; Schuetz, Mathias; Karlen, Steven D; Bird, David; Tokunaga, Naohito; Sato, Yasushi; Mansfield, Shawn D; Ralph, John; Samuels, A Lacey

2017-06-01

Many land plants evolved tall and sturdy growth habits due to specialized cells with thick lignified cell walls: tracheary elements that function in water transport and fibers that function in structural support. The objective of this study was to define how and when diverse cell populations contribute lignin precursors, monolignols, to secondary cell walls during lignification of the Arabidopsis ( Arabidopsis thaliana ) inflorescence stem. Previous work demonstrated that, when lignin biosynthesis is suppressed in fiber and tracheary element cells with thickened walls, fibers become lignin-depleted while vascular bundles still lignify, suggesting that nonlignifying neighboring xylem cells are contributing to lignification. In this work, we dissect the contributions of different cell types, specifically xylary parenchyma and fiber cells, to lignification of the stem using cell-type-specific promoters to either knock down an essential monolignol biosynthetic gene or to introduce novel monolignol conjugates. Analysis of either reductions in lignin in knockdown lines, or the addition of novel monolignol conjugates, directly identifies the xylary parenchyma and fiber cell populations that contribute to the stem lignification and the developmental timing at which each contribution is most important. © 2017 American Society of Plant Biologists. All Rights Reserved.

[Ultrastructural observation related to cell-to-cell movement and long-distance systemic transport on the hosts infected with BBWV 2].

PubMed

Hong, Jian; Wang, Wei-Bing; Zhou, Xue-Ping; Hu, Dong-Wei

2006-06-01

The alteration of ultrastructure in Pisum sativum and Vicia faba leaf cells infected with B935 isolate of BBWV 2 were investigated by electron microscopy, immunogold-labeling technique. The results showed that the membranous proliferation, virus-formed crystals and tubular structures were found in leaf cells of two hosts. At early stages of infection, the tubules containing virus-like particles associate with plasmodesmata in mesophyll cell. Immunogold particles anti-BBWV 2 were localized to the plasmodesmata modified by tubules passing through them. The membranous proliferation and virus-formed tubules were also found in the parenchyma cells, companion cells and transfer cells of vascular bundle. Some virus-like particles located within sieve tube can be labeled immunogold particles anti-BBWV 2. These suggest that BBWV 2, similar CPMV, produce tubules extending into the plasmodesmata. Virions assembled in the cytoplasm are escorted to the tubular structures through interactions with their MP and are then transported to the adjacent cell. Many 160 nm in diameter virus-formed tubules in the cytoplasm, as a special aggregate, not directly relate to cell-to-cell movement; Intact virions are long-distance sustemic transported possibly through sieve elements.

Cues for cellular assembly of vascular elastin networks

NASA Astrophysics Data System (ADS)

Kothapalli, Chandrasekhar R.

Elastin, a structural protein distributed in the extracellular matrix of vascular tissues is critical to the maintenance of vascular mechanics, besides regulation of cell-signaling pathways involved in injury response and morphogenesis. Thus, congenital absence or disease-mediated degradation of vascular elastin and its malformation within native vessels due to innately poor elastin synthesis by adult vascular cells compromise vascular homeostasis. Current elastin regenerative strategies using tissue engineering principles are limited by the progressive destabilization of tropoelastin mRNA expression in adult vascular cells and the unavailability of scaffolds that can provide cellular cues necessary to up-regulate elastin synthesis and regenerate faithful mimics of native elastin. Since our earlier studies demonstrated the elastogenic utility of hyaluronan (HA)-based cues, we have currently sought to identify a unique set of culture conditions based on HA fragments (0.756-2000 kDa), growth factors (TGF-beta1, IGF-1) and other biomolecules (Cu2+ ions, LOX), which will together enhance synthesis, crosslinking, maturation and fibrous elastin matrix formation by adult SMCs, under both healthy and inflammatory conditions. It was observed that TGF-beta1 (1 ng/mL) together with HA oligomers (0.2 microg/mL) synergistically suppressed SMC proliferation, enhanced tropoelastin (8-fold) and matrix elastin synthesis (5.5-fold), besides improving matrix yield (4.5-fold), possibly by increasing production and activity of lysyl oxidase (LOX). Though addition of IGF-1 alone did not offer any advantage, HA fragments (20-200 kDa) in the presence of IGF-1 stimulated tropoelastin and soluble elastin synthesis more than 2.2-fold, with HMW HA contributing for ˜5-fold increase in crosslinked matrix elastin synthesis. Similarly, 0.1 M of Cu2+ ions, alone or together with HA fragments stimulated synthesis of tropoelastin (4-fold) and crosslinked matrix elastin (4.5-fold), via increases in LOX protein synthesis (2.5-fold); these cues also enhanced deposition of mature elastic fibers (˜1 mum diameter) within these cultures. Interestingly, instead of copper salt addition, even release of Cu 2+ ions (˜0.1 M) from copper nanoparticles (400 ng/mL), concurrent with HA oligomers, promoted crosslinking of elastin into mature matrix, with multiple bundles of highly-crosslinked elastin fiber formation observed (diameter ˜200-500 nm). These results strongly attest to the potential individual and combined benefits of these cues to faithful elastin matrix regeneration by healthy, patient-derived cells within tissue-engineered vascular constructs. When these cues (TGF-beta1 and HA oligomers) were added to TNF-alpha-stimulated SMC cultures, model cell culture systems mimicking phenotypically-altered cells within aneurysms, they upregulated elastin matrix production, organized elastin protein into fibers, and simultaneously stabilized this matrix by attenuating production of elastolytic enzymes. Similarly these cues also attenuated inflammatory cytokines release within cells isolated from induced-aortic aneurysms in rats, and significantly upregulated elastin synthesis and matrix formation by upregulating LOX and desmosine protein amounts. The cues were also highly effective in organizing the elastin into fibrous matrix structures mimicking the native elastin deposition process. The outcomes of this study might be of tremendous use in optimizing design of HA constructs to modulate vascular healing and matrix synthesis following revascularization, and in enabling repair of elastin networks within diseased or inflammatory (aneurysmal) adult vascular tissues.

Specialised emission pattern of leaf trace in a late Permian (253 million-years old) conifer

PubMed Central

Wei, Hai-Bo; Feng, Zhuo; Yang, Ji-Yuan; Chen, Yu-Xuan; Shen, Jia-Jia; He, Xiao-Yuan

2015-01-01

Leaf traces are important structures in higher plants that connect leaves and the stem vascular system. The anatomy and emission pattern of leaf traces are well studied in extant vascular plants, but remain poorly understood in fossil lineages. We quantitatively analysed the leaf traces in the late Permian conifer Ningxiaites specialis from Northwest China based on serial sections through pith, primary and secondary xylems. A complete leaf traces emission pattern of a conifer is presented for the first time from the late Palaeozoic. Three to five monarch leaf traces are grouped in clusters, arranged in a helical phyllotaxis. The leaf traces in each cluster can be divided into upper, middle and lower portions, and initiate at the pith periphery and cross the wood horizontally. The upper leaf trace increases its diameter during the first growth increment and then diminishes completely, which indicates leaf abscission at the end of the first year. The middle trace immediately bifurcates once or twice to form two or three vascular bundles. The lower trace persists as a single bundle during its entire length. The intricate leaf trace dynamics indicates this fossil plant had a novel evolutionary habit by promoting photosynthetic capability for the matured plant. PMID:26198410

Passive restriction of blood flow and counter-current heat exchange via lingual retia in the tongue of a neonatal gray whale Eschrichtius robustus (Cetacea, Mysticeti).

PubMed

Ekdale, Eric G; Kienle, Sarah S

2015-04-01

Retia mirabilia play broad roles in cetacean physiology, including thermoregulation during feeding and pressure regulations during diving. Vascular bundles of lingual retia are described within the base of the tongue of a neonatal female gray whale (Eschrichtius robustus). Each rete consists of a central artery surrounded by four to six smaller veins. The retia and constituent vessels decrease in diameter as they extend anteriorly within the hyoglossus muscle from a position anterior to the basihyal cartilage toward the apex of the tongue. The position of the retia embedded in the hyoglossus and the anterior constriction of the vessels differs from reports of similar vascular bundles that were previously identified in gray whales. The retia likely serve as a counter-current heat exchange system to control body temperature during feeding. Cold blood flowing toward the body center within the periarterial veins would accept heat from warm blood in the central artery flowing toward the anterior end of the tongue. Although thermoregulatory systems have been identified within the mouths of a few mysticete species, the distribution of such vascular structures likely is more widespread among baleen whales than has previously been described. © 2015 Wiley Periodicals, Inc.

Transduction channels' gating can control friction on vibrating hair-cell bundles in the ear.

PubMed

Bormuth, Volker; Barral, Jérémie; Joanny, Jean-François; Jülicher, Frank; Martin, Pascal

2014-05-20

Hearing starts when sound-evoked mechanical vibrations of the hair-cell bundle activate mechanosensitive ion channels, giving birth to an electrical signal. As for any mechanical system, friction impedes movements of the hair bundle and thus constrains the sensitivity and frequency selectivity of auditory transduction. Friction is generally thought to result mainly from viscous drag by the surrounding fluid. We demonstrate here that the opening and closing of the transduction channels produce internal frictional forces that can dominate viscous drag on the micrometer-sized hair bundle. We characterized friction by analyzing hysteresis in the force-displacement relation of single hair-cell bundles in response to periodic triangular stimuli. For bundle velocities high enough to outrun adaptation, we found that frictional forces were maximal within the narrow region of deflections that elicited significant channel gating, plummeted upon application of a channel blocker, and displayed a sublinear growth for increasing bundle velocity. At low velocity, the slope of the relation between the frictional force and velocity was nearly fivefold larger than the hydrodynamic friction coefficient that was measured when the transduction machinery was decoupled from bundle motion by severing tip links. A theoretical analysis reveals that channel friction arises from coupling the dynamics of the conformational change associated with channel gating to tip-link tension. Varying channel properties affects friction, with faster channels producing smaller friction. We propose that this intrinsic source of friction may contribute to the process that sets the hair cell's characteristic frequency of responsiveness.

Mechanisms of desiccation tolerance in the bromeliad Pitcairnia burchellii Mez: biochemical adjustments and structural changes.

PubMed

Vieira, Evandro Alves; Silva, Kleber Resende; Oriani, Aline; Moro, Camila Fernandes; Braga, Marcia Regina

2017-12-01

Rocky outcrops represent the diversity center of vascular desiccation tolerant (DT) plants. Vegetation in this environment is exposed to an extended dry season and extreme conditions due to rocky soils and high sun exposure. In this study, we demonstrated that Pitcairnia burchellii, a bromeliad from rocky outcrops, tolerates intense desiccation for about 90 days due to strategies as accumulation of compatible osmolytes and antioxidant substances together with leaf morphological changes. In dehydrated plants, an increase in antioxidant activity was observed and the vacuolization of parenchyma cells was accompanied by proline accumulation in leaves and rhizomes. Precursors related to phenylpropanoid pathway increased significantly during plant dehydration. Accordingly, increases in anthocyanin and phenolic contents as well as lignin deposition were observed in leaves of dehydrated plants. Cell divisions and a decrease in stored starch were observed in the rhizomes indicating starch mobilization. Anatomical analyses revealed the presence of a more developed water-storage tissue in dehydrated leaves. During desiccation, leaves curl upwards and the adaxial V deep water-storage tissue is supported by two larger lateral vascular bundles. Cell wall folding and an increased proportion of arabinose-containing polymers was observed in leaves under dehydration, suggesting increasing of cell wall flexibility during desiccation. Such biochemical and morphological changes are consistent with the ability of P. burchellii to tolerate intense desiccation and behave as a resurrection species. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Disruption of SorCS2 reveals differences in the regulation of stereociliary bundle formation between hair cell types in the inner ear

PubMed Central

Taylor, Ruth R.; Lovett, Michael; Jagger, Daniel J.

2017-01-01

Behavioural anomalies suggesting an inner ear disorder were observed in a colony of transgenic mice. Affected animals were profoundly deaf. Severe hair bundle defects were identified in all outer and inner hair cells (OHC, IHC) in the cochlea and in hair cells of vestibular macular organs, but hair cells in cristae were essentially unaffected. Evidence suggested the disorder was likely due to gene disruption by a randomly inserted transgene construct. Whole-genome sequencing identified interruption of the SorCS2 (Sortilin-related VPS-10 domain containing protein) locus. Real-time-qPCR demonstrated disrupted expression of SorCS2 RNA in cochlear tissue from affected mice and this was confirmed by SorCS2 immuno-labelling. In all affected hair cells, stereocilia were shorter than normal, but abnormalities of bundle morphology and organisation differed between hair cell types. Bundles on OHC were grossly misshapen with significantly fewer stereocilia than normal. However, stereocilia were organised in rows of increasing height. Bundles on IHC contained significantly more stereocilia than normal with some longer stereocilia towards the centre, or with minimal height differentials. In early postnatal mice, kinocilia (primary cilia) of IHC and of OHC were initially located towards the lateral edge of the hair cell surface but often became surrounded by stereocilia as bundle shape and apical surface contour changed. In macular organs the kinocilium was positioned in the centre of the cell surface throughout maturation. There was disruption of the signalling pathway controlling intrinsic hair cell apical asymmetry. LGN and Gαi3 were largely absent, and atypical Protein Kinase C (aPKC) lost its asymmetric distribution. The results suggest that SorCS2 plays a role upstream of the intrinsic polarity pathway and that there are differences between hair cell types in the deployment of the machinery that generates a precisely organised hair bundle. PMID:28346477

Bioinspired Tuning of Hydrogel Permeability-Rigidity Dependency for 3D Cell Culture

NASA Astrophysics Data System (ADS)

Lee, Min Kyung; Rich, Max H.; Baek, Kwanghyun; Lee, Jonghwi; Kong, Hyunjoon

2015-03-01

Hydrogels are being extensively used for three-dimensional immobilization and culture of cells in fundamental biological studies, biochemical processes, and clinical treatments. However, it is still a challenge to support viability and regulate phenotypic activities of cells in a structurally stable gel, because the gel becomes less permeable with increasing rigidity. To resolve this challenge, this study demonstrates a unique method to enhance the permeability of a cell-laden hydrogel while avoiding a significant change in rigidity of the gel. Inspired by the grooved skin textures of marine organisms, a hydrogel is assembled to present computationally optimized micro-sized grooves on the surface. Separately, a gel is engineered to preset aligned microchannels similar to a plant's vascular bundles through a uniaxial freeze-drying process. The resulting gel displays significantly increased water diffusivity with reduced changes of gel stiffness, exclusively when the microgrooves and microchannels are aligned together. No significant enhancement of rehydration is achieved when the microgrooves and microchannels are not aligned. Such material design greatly enhances viability and neural differentiation of stem cells and 3D neural network formation within the gel.

Inner hair cell stereocilia movements captured in-situ by a high-speed camera with subpixel image processing

NASA Astrophysics Data System (ADS)

Wang, Yanli; Puria, Sunil; Steele, Charles R.; Ricci, Anthony J.

2018-05-01

Mechanical stimulation of the stereocilia hair bundles of the inner and outer hair cells (IHCs and OHCs, respectively) drives IHC synaptic release and OHC electromotility. The modes of hair-bundle motion can have a dramatic influence on the electrophysiological responses of the hair cells. The in vivo modes of motion are, however, unknown for both IHC and OHC bundles. In this work, we are developing technology to investigate the in situ hair-bundle motion in excised mouse cochleae, for which the hair bundles of the OHCs are embedded in the tectorial membrane but those of the IHCs are not. Motion is generated by pushing onto the stapes at 1 kHz with a glass probe coupled to a piezo stack, and recorded using a high-speed camera at 10,000 frames per second. The motions of individual IHC stereocilia and the cell boundary are analyzed using 2D and 1D Gaussian fitting algorithms, respectively. Preliminary results show that the IHC bundle moves mainly in the radial direction and exhibits a small degree of splay, and that the stereocilia in the second row move less than those in the first row, even in the same focal plane.

Developmental pathway from leaves to galls induced by a sap-feeding insect on Schinus polygamus (Cav.) Cabrera (Anacardiaceae).

PubMed

Dias, Graciela G; Ferreira, Bruno G; Moreira, Gilson R P; Isaias, Rosy M S

2013-03-01

Galling sap-feeding insects are presumed to cause only minor changes in host plant tissues, because they usually do not require development of nutritive tissues for their own use. This premise was examined through comparison of the histometry, cytometry and anatomical development of non-galled leaves and galls of Calophya duvauae (Scott) (Hemiptera: Calophyidae) on Schinus polygamus (Cav.) Cabrera (Anacardiaceae). Cell fates changed from non-galled leaves to galls during the course of tissue differentiation. C. duvauae caused changes in dermal, ground, and vascular systems of the leaves of S. polygamus. Its feeding activity induced the homogenization of the parenchyma, and the neoformation of vascular bundles and trichomes. The histometric and cytometric data revealed compensatory effects of hyperplasia and cell hypertrophy in the epidermis, with hyperplasia predominating in the adaxial epidermis. There was a balance between these processes in the other tissues. Thus, we found major differences between the developmental pathways of non-galled leaves and galls. These changes were associated with phenotypic alterations related to shelter and appropriate microenvironmental conditions for the gall inducer. The nondifferentiation of a typical nutritive tissue in this case was compared to other non-phylogenetically related arthropod gall systems, and is suggested to result from convergence associated with the piercing feeding apparatus of the corresponding gall-inducer.

Strong fascin expression promotes metastasis independent of its F-actin bundling activity.

PubMed

Heinz, Lisa S; Muhs, Stefanie; Schiewek, Johanna; Grüb, Saskia; Nalaskowski, Marcus; Lin, Yuan-Na; Wikman, Harriet; Oliveira-Ferrer, Leticia; Lange, Tobias; Wellbrock, Jasmin; Konietzny, Anja; Mikhaylova, Marina; Windhorst, Sabine

2017-12-15

High expression of the actin bundling protein Fascin increases the malignancy of tumor cells. Here we show that fascin expression is up-regulated in more malignant sub-cell lines of MDA-MB-231 cells as compared to parental cells. Since also parental MDA-MB-231 cells exhibit high fascin levels, increased fascin expression was termed as "hyperexpression". To examine the effect of fascin hyperexpression, fascin was hyperexpressed in parental MDA-MB-231 cells and metastasis was analyzed in NOD scid gamma (NSG) mice. In addition, the effect of fascin mutants with inactive or constitutively active actin bundling activity was examined. Unexpectedly, we found that hyperexpression of both, wildtype (wt) and mutant fascin strongly increased metastasis in vivo , showing that the effect of fascin hyperexpression did not depend on its actin bundling activity. Cellular assays revealed that hyperexpression of wt and mutant fascin increased adhesion of MDA-MB-231 cells while transmigration and proliferation were not affected. Since it has been shown that fascin controls adhesion by directly interacting with microtubules ( MTs), we analyzed if fascin hyperexpression affects MT dynamics. We found that at high concentrations fascin significantly increased MT dynamics in cells and in cell-free approaches. In summary our data show that strong expression of fascin in breast cancer cells increases metastasis independent of its actin bundling activity. Thus, it seems that the mechanism of fascin-stimulated metastasis depends on its concentration.

Glycine decarboxylase is confined to the bundle-sheath cells of leaves of C3-C 4 intermediate species.

PubMed

Hylton, C M; Rawsthorne, S; Smith, A M; Jones, D A; Woolhouse, H W

1988-10-01

Immunogold labelling has been used to determine the cellular distribution of glycine decarboxylase in leaves of C3, C3-C4 intermediate and C4 species in the genera Moricandia, Panicum, Flaveria and Mollugo. In the C3 species Moricandia foleyi and Panicum laxum, glycine decarboxylase was present in the mitochondria of both mesophyll and bundle-sheath cells. However, in all the C3-C4 intermediate (M. arvensis var. garamatum, M. nitens, M. sinaica, M. spinosa, M. suffruticosa, P. milioides, Flaveria floridana, F. linearis, Mollugo verticillata) and C4 (P. prionitis, F. trinervia) species studied glycine decarboxylase was present in the mitochondria of only the bundle-sheath cells. The bundle-sheath cells of all the C3-C4 intermediate species have on their centripetal faces numerous mitochondria which are larger in profile area than those in mesophyll cells and are in close association with chloroplasts and peroxisomes. Confinement of glycine decarboxylase to the bundle-sheath cells is likely to improve the potential for recapture of photorespired CO2 via the Calvin cycle and could account for the low rate of photorespiration in all C3-C4 intermediate species.

Right Atrial Anomalous Muscle Bundle Presenting with Acute Superior Vena Cava Syndrome and Pulmonary Embolism: Surgical Management.

PubMed

Madjarov, Jeko M; Katz, Michael G; Madjarova, Sophia; Madzharov, Svetozar; Arko, Frank R; Miller, David W; Robicsek, Francis

2018-05-21

An anomalous muscle bundle crossing the right atrial cavity represents a pathological finding with unproved clinical significance. This congenital anomaly may be difficult to recognize via echocardiography and could be confused with other intra-cavitary lesions. We report a case of a 53-year-old female presented to the cardio-vascular service with acute superior vena cava syndrome and sub-massive pulmonary embolism. The patient underwent venography confirming superior vena cava stenosis. A ventilation/perfusion lung scan showed two sizable perfusion defects due to pulmonary embolism. MRI and echocardiography imaging demonstrated right atrium mass. Surgery was then carried out using standard cardiopulmonary bypass; right atrial muscle bundle was excised and superior vena cava reconstruction was performed. The patient was discharged uneventfully and remains symptom-free at two years follow-up. In cases of nonmalignant pathology of superior vena cava syndrome, appropriate studies should be conducted to exclude potential congenital abnormalities such as this anomalous muscle bundle in the right atrium. Open heart surgery is a viable treatment option in select cases. Published by Elsevier Inc.

Folliculosebaceous cystic hamartoma with a neural component: an immunohistochemical study.

PubMed

Toyoda, M; Morohashi, M

1997-07-01

We present a case of follicular cystic hamartoma, a distinctive cutaneous malformation characterized by marked overgrowth of folliculosebaceous units accompanied by appreciable mesenchymal alterations, including fibroplasia, increased vascular components, and numerous adipocytes. A conspicuous feature of our case is an aggregation of thick trespassing nerve bundles in the deep portion of the neoplasm. An immunohistochemical study revealed the nerve bundles were immunoreactive for the general neuronal marker protein gene product 9.5. The nerves, however, stained negatively with antibodies against neuropeptides such as calcitonin gene-related peptide, substance P, vasoactive intestinal polypeptide, and neuropeptide Y, all of which are known to be contained in normal cutaneous nerves. The presence of these aberrant nerve bundles devoid of the normal expression of neuropeptides supports the concept that folliculosebaceous cystic hamartoma is a true, tumor-like malformation characterized by abnormal overgrowth of normal components of the skin.

Effects of Mechanical Loading on the Dynamics of Hair-Cell Stereociliary Bundles

NASA Astrophysics Data System (ADS)

Fredrickson, Lea

Hearing is remarkably sensitive and still not entirely understood. Hair cells of the inner ear are the mechano-electrical transducers of sound and understanding how they function is essential to the understanding of hearing in general. Spontaneous oscillations exhibited by stereociliary bundles of the bullfrog sacculus provide a useful probe for the study of the hair cells' internal dynamic state. In this work we study the effects of mechanical loading on these hair-cell bundles in order to study their dynamics. When applying stiffness loads, we find that the spontaneous oscillation profile changes from multimode to single mode with light loading, and decreases in amplitude and increases in frequency with stiffer loads. We also find that tuning decreases with increasing load such that at loads comparable to in vivo conditions the tuning is flat. We further explore loading via deflections to hair cell bundles, both in the form of steady-state offsets and slow ramps. We find that steady state offsets lead to significant modulation of the characteristic frequency of response, decreasing the frequency in the channels closed direction (negative) and increasing it in the channels open direction (positive). Attachment to the overlying membrane was found, in vitro, to affect bundle offset position in hair cells of the bullfrog sacculus. Application of similar offsets on free-standing, spontaneously oscillating hair bundles shows modulation of their dynamic state, i.e. oscillation profile, characteristic frequency, and response to stimulus. Large offsets are found to arrest spontaneous oscillations, which recover upon reversal of the stimulus. The dynamical state of the hair bundle is dependent on both the history and direction of the offset stimulus. Oscillation suppression occurs much more readily in the negative direction and the bundle behavior approaching quiescence is distinct from that in the positive direction. With the change in spontaneous oscillation frequency and profile comes a change in the phase-locked response amplitude, dependent on bundle offset, winch extends the range of detection frequencies of the hair cell. We explore the broadband phase-locked response of spontaneously oscillating saccular hair cell bundles subject to time-dependent mechanical deflections. The experimental phase-locked amplitude shows an Arnold Tongue, consistent with theoretically predicted dynamical behavior. An offset that steadily increases in time, imposed on the position of the bundle to explore its dynamics at the zero frequency limit, is observed to progressively suppress spontaneous oscillations in a transition that displays strong frequency modulation, with the frequency vanishing at the critical point. When deflected at a faster rate and when allowed to recover to the oscillatory regime, the bundles also displayed a modulation in the amplitude of oscillation. We propose the dynamics of this transition to be dominated by a multi-critical region such that slight variations of a control parameter can produce either an infinite-period, supercritical Hopf, or Bogdanov-Takens bifurcation.

The spectrum of canine cutaneous perivascular wall tumors: morphologic, phenotypic and clinical characterization.

PubMed

Avallone, G; Helmbold, P; Caniatti, M; Stefanello, D; Nayak, R C; Roccabianca, P

2007-09-01

Perivascular wall tumors (PWTs) are defined as neoplasms deriving from mural cells of blood vessels, excluding the endothelial lining. The spectrum of human cutaneous PWT includes glomus tumor, hemangiopericytoma (HEP), myopericytoma, angioleiomyoma/sarcoma, angiomyofibroblastoma, and angiofibroma. The purpose of this study was to revise clinical presentation, cytology, histopathology, and immunohistology of canine cutaneous PWT with cytology typical of canine HEP. Diagnosis was established on the basis of vascular growth patterns (staghorn, placentoid, perivascular whorling, bundles from media) and immunohistology, including 7 smooth muscle markers and the cell membrane ganglioside of unknown origin recognized by the antibody 3G5 (CMG-3G5). Twenty cases were included. Ages ranged from 6 to 13 years; 12 dogs were males and 8 were females, and there was a prevalence of crossbreeds. Tumors arose from a single site with preferential acral location (10/20). Cytology revealed moderate to high cellularity in all cases, cohesive groups of cells (19/20), capillaries (18/20), and bi- to multinucleated cells (18/20). Six myopericytomas, 5 angioleiomyomas, 2 angioleiomyosarcomas, 2 HEP, 1 angiofibroma, and 1 adventitial tumor were identified. A definitive diagnosis was not possible in 3 cases. Smoothelin, heavy caldesmon, desmin, myosin, calponin, and CMG-3G5 were the most valuable markers to differentially diagnose canine PWT. Similar to reports in humans, canine HEP embodied a spectrum of neoplastic entities arising from different vascular mural cells. Before canine PWTs are assimilated into one prognostic category, a consistent classification and characterization of their biology is necessary. As proposed in humans, HEP should also be considered a diagnosis of exclusion in dogs.

From Cell Differentiation to Cell Collectives: Bacillus subtilis Uses Division of Labor to Migrate

PubMed Central

van Gestel, Jordi; Vlamakis, Hera; Kolter, Roberto

2015-01-01

The organization of cells, emerging from cell–cell interactions, can give rise to collective properties. These properties are adaptive when together cells can face environmental challenges that they separately cannot. One particular challenge that is important for microorganisms is migration. In this study, we show how flagellum-independent migration is driven by the division of labor of two cell types that appear during Bacillus subtilis sliding motility. Cell collectives organize themselves into bundles (called “van Gogh bundles”) of tightly aligned cell chains that form filamentous loops at the colony edge. We show, by time-course microscopy, that these loops migrate by pushing themselves away from the colony. The formation of van Gogh bundles depends critically on the synergistic interaction of surfactin-producing and matrix-producing cells. We propose that surfactin-producing cells reduce the friction between cells and their substrate, thereby facilitating matrix-producing cells to form bundles. The folding properties of these bundles determine the rate of colony expansion. Our study illustrates how the simple organization of cells within a community can yield a strong ecological advantage. This is a key factor underlying the diverse origins of multicellularity. PMID:25894589

Actin-binding proteins sensitively mediate F-actin bundle stiffness

NASA Astrophysics Data System (ADS)

Claessens, Mireille M. A. E.; Bathe, Mark; Frey, Erwin; Bausch, Andreas R.

2006-09-01

Bundles of filamentous actin (F-actin) form primary structural components of a broad range of cytoskeletal processes including filopodia, sensory hair cell bristles and microvilli. Actin-binding proteins (ABPs) allow the cell to tailor the dimensions and mechanical properties of the bundles to suit specific biological functions. Therefore, it is important to obtain quantitative knowledge on the effect of ABPs on the mechanical properties of F-actin bundles. Here we measure the bending stiffness of F-actin bundles crosslinked by three ABPs that are ubiquitous in eukaryotes. We observe distinct regimes of bundle bending stiffness that differ by orders of magnitude depending on ABP type, concentration and bundle size. The behaviour observed experimentally is reproduced quantitatively by a molecular-based mechanical model in which ABP shearing competes with F-actin extension/compression. Our results shed new light on the biomechanical function of ABPs and demonstrate how single-molecule properties determine mesoscopic behaviour. The bending mechanics of F-actin fibre bundles are general and have implications for cytoskeletal mechanics and for the rational design of functional materials.

Visualization of Live Cochlear Stereocilia at a Nanoscale Resolution Using Hopping Probe Ion Conductance Microscopy

PubMed Central

Vélez-Ortega, A. Catalina; Frolenkov, Gregory I.

2016-01-01

The mechanosensory apparatus that detects sound-induced vibrations in the cochlea is located on the apex of the auditory sensory hair cells and it is made up of actin-filled projections, called stereocilia. In young rodents, stereocilia bundles of auditory hair cells consist of 3 to 4 rows of stereocilia of decreasing height and varying thickness. Morphological studies of the auditory stereocilia bundles in live hair cells have been challenging because the diameter of each stereocilium is near or below the resolution limit of optical microscopy. In theory, scanning probe microscopy techniques, such as atomic force microscopy, could visualize the surface of a living cell at a nanoscale resolution. However, their implementations for hair cell imaging have been largely unsuccessful because the probe usually damages the bundle and disrupts the bundle cohesiveness during imaging. We overcome these limitations by using hopping probe ion conductance microscopy (HPICM), a non-contact scanning probe technique that is ideally suited for the imaging of live cells with a complex topography. Organ of Corti explants are placed in a physiological solution and then a glass nanopipette –which is connected to a 3D-positioning piezoelectric system and to a patch clamp amplifier– is used to scan the surface of the live hair cells at nanometer resolution without ever touching the cell surface. Here we provide a detailed protocol for the imaging of mouse or rat stereocilia bundles in live auditory hair cells using HPICM. We provide information about the fabrication of the nanopipettes, the calibration of the HPICM setup, the parameters we have optimized for the imaging of live stereocilia bundles and, lastly, a few basic image post-processing manipulations. PMID:27259929

Visualization of Live Cochlear Stereocilia at a Nanoscale Resolution Using Hopping Probe Ion Conductance Microscopy.

PubMed

Vélez-Ortega, A Catalina; Frolenkov, Gregory I

2016-01-01

The mechanosensory apparatus that detects sound-induced vibrations in the cochlea is located on the apex of the auditory sensory hair cells and it is made up of actin-filled projections, called stereocilia. In young rodents, stereocilia bundles of auditory hair cells consist of 3-4 rows of stereocilia of decreasing height and varying thickness. Morphological studies of the auditory stereocilia bundles in live hair cells have been challenging because the diameter of each stereocilium is near or below the resolution limit of optical microscopy. In theory, scanning probe microscopy techniques, such as atomic force microscopy, could visualize the surface of a living cell at a nanoscale resolution. However, their implementations for hair cell imaging have been largely unsuccessful because the probe usually damages the bundle and disrupts the bundle cohesiveness during imaging. We overcome these limitations by using hopping probe ion conductance microscopy (HPICM), a non-contact scanning probe technique that is ideally suited for the imaging of live cells with a complex topography. Organ of Corti explants are placed in a physiological solution and then a glass nanopipette-which is connected to a 3D-positioning piezoelectric system and to a patch clamp amplifier-is used to scan the surface of the live hair cells at nanometer resolution without ever touching the cell surface.Here, we provide a detailed protocol for the imaging of mouse or rat stereocilia bundles in live auditory hair cells using HPICM. We provide information about the fabrication of the nanopipettes, the calibration of the HPICM setup, the parameters we have optimized for the imaging of live stereocilia bundles and, lastly, a few basic image post-processing manipulations.

Spontaneous Oscillation by Hair Bundles of the Bullfrog's Sacculus

PubMed Central

Martin, Pascal; Bozovic, D.; Choe, Y.; Hudspeth, A. J.

2007-01-01

One prominent manifestation of mechanical activity in hair cells is spontaneous otoacoustic emission, the unprovoked emanation of sound by an internal ear. Because active hair-bundle motility probably constitutes the active process of non-mammalian hair cells, we investigated the ability of hair bundles in the bullfrog's sacculus to produce oscillations that might underlie spontaneous otoacoustic emissions. When maintained in the ear's normal ionic milieu, many bundles oscillated spontaneously through distances as great as 80 nm at frequencies of 5-50 Hz. Whole-cell recording disclosed that the positive phase of movement was associated with the opening of transduction channels. Gentamicin, which blocks transduction channels, reversibly arrested oscillation; drugs that affect the cAMP phosphorylation pathway and might influence myosin's activity altered the rate of oscillation. Increasing the Ca2+ concentration rendered oscillations faster and smaller until they were suppressed; lowering the Ca2+ concentration moderately with chelators had the opposite effect. When a bundle was offset with a stimulus fiber, oscillations were transiently suppressed but gradually resumed. Loading a bundle by partial displacement clamping, which simulated the presence of the accessory structures to which a bundle is ordinarily attached, increased the frequency and diminished the magnitude of oscillation. These observations accord with a model in which oscillations arise from the interplay of the hair bundle's negative stiffness with the activity of adaptation motors and with Ca2+-dependent relaxation of gating springs. PMID:12805294

Branched actin networks push against each other at adherens junctions to maintain cell-cell adhesion.

PubMed

Efimova, Nadia; Svitkina, Tatyana M

2018-05-07

Adherens junctions (AJs) are mechanosensitive cadherin-based intercellular adhesions that interact with the actin cytoskeleton and carry most of the mechanical load at cell-cell junctions. Both Arp2/3 complex-dependent actin polymerization generating pushing force and nonmuscle myosin II (NMII)-dependent contraction producing pulling force are necessary for AJ morphogenesis. Which actin system directly interacts with AJs is unknown. Using platinum replica electron microscopy of endothelial cells, we show that vascular endothelial (VE)-cadherin colocalizes with Arp2/3 complex-positive actin networks at different AJ types and is positioned at the interface between two oppositely oriented branched networks from adjacent cells. In contrast, actin-NMII bundles are located more distally from the VE-cadherin-rich zone. After Arp2/3 complex inhibition, linear AJs split, leaving gaps between cells with detergent-insoluble VE-cadherin transiently associated with the gap edges. After NMII inhibition, VE-cadherin is lost from gap edges. We propose that the actin cytoskeleton at AJs acts as a dynamic push-pull system, wherein pushing forces maintain extracellular VE-cadherin transinteraction and pulling forces stabilize intracellular adhesion complexes. © 2018 Efimova and Svitkina.

Real-Time Dynamics of Emerging Actin Networks in Cell-Mimicking Compartments

PubMed Central

Deshpande, Siddharth; Pfohl, Thomas

2015-01-01

Understanding the cytoskeletal functionality and its relation to other cellular components and properties is a prominent question in biophysics. The dynamics of actin cytoskeleton and its polymorphic nature are indispensable for the proper functioning of living cells. Actin bundles are involved in cell motility, environmental exploration, intracellular transport and mechanical stability. Though the viscoelastic properties of actin-based structures have been extensively probed, the underlying microstructure dynamics, especially their disassembly, is not fully understood. In this article, we explore the rich dynamics and emergent properties exhibited by actin bundles within flow-free confinements using a microfluidic set-up and epifluorescence microscopy. After forming entangled actin filaments within cell-sized quasi two-dimensional confinements, we induce their bundling using three different fundamental mechanisms: counterion condensation, depletion interactions and specific protein-protein interactions. Intriguingly, long actin filaments form emerging networks of actin bundles via percolation leading to remarkable properties such as stress generation and spindle-like intermediate structures. Simultaneous sharing of filaments in different links of the network is an important parameter, as short filaments do not form networks but segregated clusters of bundles instead. We encounter a hierarchical process of bundling and its subsequent disassembly. Additionally, our study suggests that such percolated networks are likely to exist within living cells in a dynamic fashion. These observations render a perspective about differential cytoskeletal responses towards numerous stimuli. PMID:25785606

Studying microstructure and microstructural changes in plant tissues by advanced diffusion magnetic resonance imaging techniques

PubMed Central

Morozov, Darya; Tal, Iris; Pisanty, Odelia; Shani, Eilon

2017-01-01

Abstract As sessile organisms, plants must respond to the environment by adjusting their growth and development. Most of the plant body is formed post-embryonically by continuous activity of apical and lateral meristems. The development of lateral adventitious roots is a complex process, and therefore the development of methods that can visualize, non-invasively, the plant microstructure and organ initiation that occur during growth and development is of paramount importance. In this study, relaxation-based and advanced diffusion magnetic resonance imaging (MRI) methods including diffusion tensor (DTI), q-space diffusion imaging (QSI), and double-pulsed-field-gradient (d-PFG) MRI, at 14.1 T, were used to characterize the hypocotyl microstructure and the microstructural changes that occurred during the development of lateral adventitious roots in tomato. Better contrast was observed in relaxation-based MRI using higher in-plane resolution but this also resulted in a significant reduction in the signal-to-noise ratio of the T2-weighted MR images. Diffusion MRI revealed that water diffusion is highly anisotropic in the vascular cylinder. QSI and d-PGSE MRI showed that in the vascular cylinder some of the cells have sizes in the range of 6–10 μm. The MR images captured cell reorganization during adventitious root formation in the periphery of the primary vascular bundles, adjacent to the xylem pole that broke through the cortex and epidermis layers. This study demonstrates that MRI and diffusion MRI methods allow the non-invasive study of microstructural features of plants, and enable microstructural changes associated with adventitious root formation to be followed. PMID:28398563

Transcriptomic Analysis Provides Insights into Grafting Union Development in Pecan (Carya illinoinensis).

PubMed

Mo, Zhenghai; Feng, Gang; Su, Wenchuan; Liu, Zhuangzhuang; Peng, Fangren

2018-02-05

Pecan ( Carya illinoinensis ), as a popular nut tree, has been widely planted in China in recent years. Grafting is an important technique for its cultivation. For a successful grafting, graft union development generally involves the formation of callus and vascular bundles at the graft union. To explore the molecular mechanism of graft union development, we applied high throughput RNA sequencing to investigate the transcriptomic profiles of graft union at four timepoints (0 days, 8 days, 15 days, and 30 days) during the pecan grafting process. After de novo assembly, 83,693 unigenes were obtained, and 40,069 of them were annotated. A total of 12,180 differentially expressed genes were identified between by grafting. Genes involved in hormone signaling, cell proliferation, xylem differentiation, cell elongation, secondary cell wall deposition, programmed cell death, and reactive oxygen species (ROS) scavenging showed significant differential expression during the graft union developmental process. In addition, we found that the content of auxin, cytokinin, and gibberellin were accumulated at the graft unions during the grafting process. These results will aid in our understanding of successful grafting in the future.

Transcriptomic Analysis Provides Insights into Grafting Union Development in Pecan (Carya illinoinensis)

PubMed Central

Mo, Zhenghai; Feng, Gang; Su, Wenchuan; Liu, Zhuangzhuang; Peng, Fangren

2018-01-01

Pecan (Carya illinoinensis), as a popular nut tree, has been widely planted in China in recent years. Grafting is an important technique for its cultivation. For a successful grafting, graft union development generally involves the formation of callus and vascular bundles at the graft union. To explore the molecular mechanism of graft union development, we applied high throughput RNA sequencing to investigate the transcriptomic profiles of graft union at four timepoints (0 days, 8 days, 15 days, and 30 days) during the pecan grafting process. After de novo assembly, 83,693 unigenes were obtained, and 40,069 of them were annotated. A total of 12,180 differentially expressed genes were identified between by grafting. Genes involved in hormone signaling, cell proliferation, xylem differentiation, cell elongation, secondary cell wall deposition, programmed cell death, and reactive oxygen species (ROS) scavenging showed significant differential expression during the graft union developmental process. In addition, we found that the content of auxin, cytokinin, and gibberellin were accumulated at the graft unions during the grafting process. These results will aid in our understanding of successful grafting in the future. PMID:29401757

* Hierarchically Structured Electrospun Scaffolds with Chemically Conjugated Growth Factor for Ligament Tissue Engineering.

PubMed

Pauly, Hannah M; Sathy, Binulal N; Olvera, Dinorath; McCarthy, Helen O; Kelly, Daniel J; Popat, Ketul C; Dunne, Nicholas J; Haut Donahue, Tammy Lynn

2017-08-01

The anterior cruciate ligament (ACL) of the knee is vital for proper joint function and is commonly ruptured during sports injuries or car accidents. Due to a lack of intrinsic healing capacity and drawbacks with allografts and autografts, there is a need for a tissue-engineered ACL replacement. Our group has previously used aligned sheets of electrospun polycaprolactone nanofibers to develop solid cylindrical bundles of longitudinally aligned nanofibers. We have shown that these nanofiber bundles support cell proliferation and elongation and the hierarchical structure and material properties are similar to the native human ACL. It is possible to combine multiple nanofiber bundles to create a scaffold that attempts to mimic the macroscale structure of the ACL. The goal of this work was to develop a hierarchical bioactive scaffold for ligament tissue engineering using connective tissue growth factor (CTGF)-conjugated nanofiber bundles and evaluate the behavior of mesenchymal stem cells (MSCs) on these scaffolds in vitro and in vivo. CTGF was immobilized onto the surface of individual nanofiber bundles or scaffolds consisting of multiple nanofiber bundles. The conjugation efficiency and the release of conjugated CTGF were assessed using X-ray photoelectron spectroscopy, assays, and immunofluorescence staining. Scaffolds were seeded with MSCs and maintained in vitro for 7 days (individual nanofiber bundles), in vitro for 21 days (scaled-up scaffolds of 20 nanofiber bundles), or in vivo for 6 weeks (small scaffolds of 4 nanofiber bundles), and ligament-specific tissue formation was assessed in comparison to non-CTGF-conjugated control scaffolds. Results showed that CTGF conjugation encouraged cell proliferation and ligament-specific tissue formation in vitro and in vivo. The results suggest that hierarchical electrospun nanofiber bundles conjugated with CTGF are a scalable and bioactive scaffold for ACL tissue engineering.

Erk regulation of actin capping and bundling by Eps8 promotes cortex tension and leader bleb-based migration

PubMed Central

Logue, Jeremy S; Cartagena-Rivera, Alexander X; Baird, Michelle A; Davidson, Michael W; Chadwick, Richard S; Waterman, Clare M

2015-01-01

Within the confines of tissues, cancer cells can use blebs to migrate. Eps8 is an actin bundling and capping protein whose capping activity is inhibited by Erk, a key MAP kinase that is activated by oncogenic signaling. We tested the hypothesis that Eps8 acts as an Erk effector to modulate actin cortex mechanics and thereby mediate bleb-based migration of cancer cells. Cells confined in a non-adhesive environment migrate in the direction of a very large ‘leader bleb.’ Eps8 bundling activity promotes cortex tension and intracellular pressure to drive leader bleb formation. Eps8 capping and bundling activities act antagonistically to organize actin within leader blebs, and Erk mediates this effect. An Erk biosensor reveals concentrated kinase activity within leader blebs. Bleb contents are trapped by the narrow neck that separates the leader bleb from the cell body. Thus, Erk activity promotes actin bundling by Eps8 to enhance cortex tension and drive the bleb-based migration of cancer cells under non-adhesive confinement. DOI: http://dx.doi.org/10.7554/eLife.08314.001 PMID:26163656

Contribution of actin filaments to the global compressive properties of fibroblasts.

PubMed

Ujihara, Yoshihiro; Nakamura, Masanori; Miyazaki, Hiroshi; Wada, Shigeo

2012-10-01

Actin filaments are often regarded as tension-bearing components. Here, we examined the effects of actin filaments on global compressive properties of cells experimentally and numerically. Fibroblasts were harvested from the patellar tendon of a mature Japanese white rabbit and treated with cytochalasin D to depolymerize the actin filaments. Intact cells and cells with disrupted actin filaments were subjected to the compressive tests. Each floating cell was held between the cantilever and compressive plates and compressed by moving the compressive plate with a linear actuator to obtain a load-deformation curve under quasi-static conditions. The experimental results demonstrated that the initial stiffness of a cell with disrupted actin filaments decreased by 51%. After the experiments, we simulated the compressive test of cells with/without bundles of actin filaments. A bundle of actin filaments was modeled as a tension-bearing component that generates a force based on Hooke's law only when it was elongated. By contrast, if it was shortened, it was assumed to exert no force. The computational results revealed that the alignment of bundles of actin filaments significantly affected the cell stiffness. In addition, the passive reorientation of bundles of actin filaments perpendicular to the compression induced an increase in the resistance to the vertical elongation of a cell and thereby increased the cell stiffness. These results clearly indicated that bundles of actin filaments contribute to the compressive properties of a cell, even if they are tension-bearing components. Copyright © 2012 Elsevier Ltd. All rights reserved.

Mutations in cadherin 23 affect tip links in zebrafish sensory hair cells.

PubMed

Söllner, Christian; Rauch, Gerd-Jörg; Siemens, Jan; Geisler, Robert; Schuster, Stephan C; Müller, Ulrich; Nicolson, Teresa

2004-04-29

Hair cells have highly organized bundles of apical projections, or stereocilia, that are deflected by sound and movement. Displacement of stereocilia stretches linkages at the tips of stereocilia that are thought to gate mechanosensory channels. To identify the molecular machinery that mediates mechanotransduction in hair cells, zebrafish mutants were identified with defects in balance and hearing. In sputnik mutants, stereociliary bundles are splayed to various degrees, with individuals displaying reduced or absent mechanotransduction. Here we show that the defects in sputnik mutants are caused by mutations in cadherin 23 (cdh23). Mutations in Cdh23 also cause deafness and vestibular defects in mice and humans, and the protein is present in hair bundles. We show that zebrafish Cdh23 protein is concentrated near the tips of hair bundles, and that tip links are absent in homozygous sputnik(tc317e) larvae. Moreover, tip links are absent in larvae carrying weak alleles of cdh23 that affect mechanotransduction but not hair bundle integrity. We conclude that Cdh23 is an essential tip link component required for hair-cell mechanotransduction.

Comparative transduction mechanisms of hair cells in the bullfrog utriculus. II. Sensitivity and response dynamics to hair bundle displacement

NASA Technical Reports Server (NTRS)

Baird, R. A.

1994-01-01

1. Hair cells in whole-mount in vitro preparations of the utricular macula of the bullfrog (Rana catesbeiana) were selected according to their macular location and hair bundle morphology. The sensitivity and response dynamics of selected hair cells to natural stimulation were examined by recording their voltage responses to step and sinusoidal hair bundle displacements applied to their longest stereocilia. 2. The voltage responses of 31 hair cells to sinusoidal hair bundle displacements were characterized by their gains and phases, taken with respect to peak hair bundle displacement. The gains of Type B and Type C cells at both 0.5 and 5.0 Hz were markedly lower than those of Type F and Type E cells. Phases, with the exception of Type C cells, lagged hair bundle displacement at 0.5 Hz. Type C cells had phase leads of 25-40 degrees. At 5.0 Hz, response phases in all cells were phase lagged with respect to those at 0.5 Hz. Type C cells had larger gains and smaller phase leads at 5.0 Hz than at 0.5 Hz, suggesting the presence of low-frequency adaptation. 3. Displacement-response curves, derived from the voltage responses to 5.0-Hz sinusoids, were sigmoidal in shape and asymmetrical, with the depolarizing response having a greater magnitude and saturating less abruptly than the hyperpolarizing response. When normalized to their largest displacement the linear ranges of these curves varied from < 0.5 to 1.25 microns and were largest in Type B and smallest in Type F and Type E cells. Sensitivity, defined as the slope of the normalized displacement-response curve, was inversely correlated with linear range. 4. The contribution of geometric factors associated with the hair bundle to linear range and sensitivity were predicted from realistic models of utricular hair bundles created using morphological data obtained from light and electron microscopy. Three factors, including 1) the inverse ratio of the lengths of the kinocilium and longest stereocilia, representing the lever arm between kinociliary and stereociliary displacement; 2) tip link extension/linear displacement, largely a function of stereociliary height and separation; and 3) stereociliary number, an estimate of the number of transduction channels, were considered in this analysis. The first of these factors was quantitatively more important than the latter two factors and their total contribution was largest in Type B and Type C cells. Theoretical models were also used to calculate the relation between rotary and linear displacement.(ABSTRACT TRUNCATED AT 400 WORDS).

Carbon dioxide and water vapor high temperature electrolysis

NASA Technical Reports Server (NTRS)

Isenberg, Arnold O.; Verostko, Charles E.

1989-01-01

The design, fabrication, breadboard testing, and the data base obtained for solid oxide electrolysis systems that have applications for planetary manned missions and habitats are reviewed. The breadboard tested contains sixteen tubular cells in a closely packed bundle for the electrolysis of carbon dioxide and water vapor. The discussion covers energy requirements, volume, weight, and operational characteristics related to the measurement of the reactant and product gas compositions, temperature distribution along the electrolyzer tubular cells and through the bundle, and thermal energy losses. The reliability of individual cell performance in the bundle configuration is assessed.

Microfilament regulatory protein MENA increases activity of RhoA and promotes metastasis of hepatocellular carcinoma.

PubMed

Lin, Ling; Yang, Xiao-Mei; Li, Jun; Zhang, Yan-Li; Qin, Wenxin; Zhang, Zhi-Gang

2014-09-10

Mammalian enabled (MENA), usually known as a direct regulator of microfilament polymerization and bundling, promotes metastasis in various cancers. Here we focus on the role of MENA in hepatocellular carcinoma (HCC) metastasis and the relevant mechanism from the view of RhoA activity regulation. By HCC tissue microarray analysis, we found that MENA expression was positively associated with satellite lesions (P<0.01) and vascular invasion (P<0.01). Cases with membrane reinforcement of MENA staining in HCC tissues had significantly higher rates of early recurrence in the intermediate MENA expression group. Knockdown of MENA significantly suppressed HCC cell migration and invasion in vitro, as well as their intrahepatic and distant metastasis in vivo. Knockdown of MENA also decreased filopodia and stress fibers in SMMC-7721 cells. Furthermore, a decrease of RhoA activity was detected by a pull-down assay in SMMC-7721-shMENA cells. The ROCK inhibitor, Y-27632, suppressed migration of both MENA knockdown SMMC-7721 cells and control cells, but diminished their difference. Thus, our findings suggest that MENA promotes HCC cell motility by activating RhoA. Copyright © 2014 Elsevier Inc. All rights reserved.

Stationary organization of the actin cytoskeleton in Vallisneria: the role of stable microfilaments at the end walls.

PubMed

Ryu, J H; Takagi, S; Nagai, R

1995-04-01

In mesophyll cells of the aquatic angiosperm Vallisneria gigantea, bundles of microfilaments (MFs) serve as tracks for the rotational streaming of the cytoplasm, which occurs along the two longer side walls and the two shorter end walls. The stationary organization of these bundles has been shown to depend on the association of the bundles with the plasma membrane at the end walls. To identify the sites of such association, the effects of cytochalasin B (CB) on the configuration of the bundles of MFs were examined. In the case of the side walls, MFs were completely disrupted after treatment with CB at 100 micrograms/ml for 24 hours. By contrast, in the case of the end walls, a number of partially disrupted MFs remained even after 48 hours of treatment. After removal of CB, a completely normal arrangement of bundles of MFs was once again evident within 24 hours after a rather complicated process of reassembly. When reassembly had been completed, the direction of cytoplasmic streaming was reversed only in a small fraction of the treated cells, suggesting that bundles of MFs are anchored and stabilized at the end walls of each cell and that the polarity of reorganized bundles and, therefore, the direction of the cytoplasmic streaming is determined in a manner that depends on the original polarity of MFs that remained in spite of the disruptive action of CB. By contrast, the direction of reinitiated cytoplasmic streaming was reversed in 50% of cells in which the bundles of MFs had been completely disrupted by exogenously applied trypsin prior treatment with CB.(ABSTRACT TRUNCATED AT 250 WORDS)

Generator module architecture for a large solid oxide fuel cell power plant

DOEpatents

Gillett, James E.; Zafred, Paolo R.; Riggle, Matthew W.; Litzinger, Kevin P.

2013-06-11

A solid oxide fuel cell module contains a plurality of integral bundle assemblies, the module containing a top portion with an inlet fuel plenum and a bottom portion receiving air inlet feed and containing a base support, the base supports dense, ceramic exhaust manifolds which are below and connect to air feed tubes located in a recuperator zone, the air feed tubes passing into the center of inverted, tubular, elongated, hollow electrically connected solid oxide fuel cells having an open end above a combustion zone into which the air feed tubes pass and a closed end near the inlet fuel plenum, where the fuel cells comprise a fuel cell stack bundle all surrounded within an outer module enclosure having top power leads to provide electrical output from the stack bundle, where the fuel cells operate in the fuel cell mode and where the base support and bottom ceramic air exhaust manifolds carry from 85% to all 100% of the weight of the stack, and each bundle assembly has its own control for vertical and horizontal thermal expansion control.

Xylem development in prunus flower buds and the relationship to deep supercooling.

PubMed

Ashworth, E N

1984-04-01

Xylem development in eight Prunus species was examined and the relationship to deep supercooling assessed. Dormant buds of six species, P. armeniaca, P. avium, P. cerasus, P. persica, P. salicina, and P. sargentii deep supercooled. Xylem vessel elements were not observed within the dormant floral primordia of these species. Instead, discrete bundles containing procambial cells were observed. Vascular differentiation resumed and xylem continuity was established during the time that the capacity to deep supercool was lost. In P. serotina and P. virginiana, two species which do not supercool, xylem vessels ran the length of the inflorescence and presumably provided a conduit for the spread of ice into the bud. The results support the hypothesis that the lack of xylem continuity is an important feature of buds which deep supercool.

Optical research of biomaterials of Sorbulak

NASA Astrophysics Data System (ADS)

Esyrev, O. V.; Kupchishin, A. A.; Kupchishin, A. I.; Voronova, N. A.

2016-02-01

Within the framework of optical research it was established that on the unpolluted samples of sedge stems occurs structuring of material, whereas on contaminated and irradiated blurring of its structure takes place. Sampling of sedges and rushes for research was carried out in areas near the first dam Sorbulak. For comparison, samples of same materials were taken far away from populated areas. Irradiation was carried out with high-energy electrons with energy of 2 MeV and integral dose of 3·105 Gr. Irradiation leads to a more pronounced structuredness of material. There is a significant difference in the structural elements (epidermis, vascular bundles, parenchymal cells, etc.). There are traced dark spots and bands associated with the presence of huge amounts of heavy metals against the background of a green matrix.

X-ray coherent diffraction imaging of cellulose fibrils in situ.

PubMed

Lal, Jyotsana; Harder, Ross; Makowski, Lee

2011-01-01

Cellulose is the most abundant renewable source of organic molecules on earth[1]. As fossil fuel reserves become depleted, the use of cellulose as a feed stock for fuels and chemicals is being aggressively explored. Cellulose is a linear polymer of glucose that packs tightly into crystalline fibrils that make up a substantial proportion of plant cell walls. Extraction of the cellulose chains from these fibrils in a chemically benign process has proven to be a substantial challenge [2]. Monitoring the deconstruction of the fibrils in response to physical and chemical treatments would expedite the development of efficient processing methods. As a step towards achieving that goal, we here describe Bragg-coherent diffraction imaging (CDI) as an approach to producing images of cellulose fibrils in situ within vascular bundles from maize.

ECM remodeling and its plasticity

NASA Astrophysics Data System (ADS)

Feng, Jingchen; Jones, Christopher A. R.; Cibula, Matthew; Mao, Xiaoming; Sander, Leonard M.; Levine, Herbert; Sun, Bo

The mechanical interactions between cells and Extracellular Matrix (ECM) are of great importance in many cellular processes. These interactions are reciprocal, i.e. contracting cells pull and reorganize the surrounding matrix, while the remodeled matrix feeds back to regulate cell activities. Recent experiments show in collagen gels with densely distributed cells, aligned fiber bundles are formed in the direction between neighboring cells. Fibers flow into the center region between contracting cell pairs in this process, which causes the concentration of fibers in the fiber bundles to become significantly enhanced. Using an extended lattice-based model, we show that viscoelasticity plays an essential role in ECM remodeling and contributes to the enhanced concentration in fiber bundles. We further characterize ECM plasticity within our model and verify our results with rheometer experiments.

Active Coupled Oscillators in the Inner Ear

NASA Astrophysics Data System (ADS)

Strimbu, Clark Elliott

Auditory and vestibular systems are endowed with an active process that enables them to detect signals as small as a few Angstroms; they also exhibit frequency selectivity; show strong nonlinearities; and can exhibit as spontaneous activity. Much of this active process comes from the sensory hair cells at the periphery of the auditory and vestibular systems. Each hair cell is capped by an eponymous hair bundle, a specialized structure that transduces mechanical forces into electrical signals. Experiments on mechanically decoupled cells from the frog sacculus have shown that individual hair bundles behave in an active manner analogous to an intact organ suggesting a common cellular basis for the active processes seen in many species. In particular, mechanically decoupled hair bundles show rapid active movements in response to transient stimuli and exhibit spontaneous oscillations. However, a single mechanosensitive hair cell is unable to match the performance of an entire organ. In vivo, hair bundles are often coupled to overlying membranes, gelatinous extracellular matrices. We used an in vitro preparation of the frog sacculus in which the otolithic membrane has been left intact. Under natural coupling conditions, there is a strong degree of correlation across the saccular epithelium, suggesting that the collective response of many cells contributes to the extreme sensitivity of this organ. When the membrane is left intact, the hair bundles do not oscillate spontaneously, showing that the natural coupling and loading tunes them into a quiescent regime. However, when stimulated by a pulse, the bundles show a rapid biphasic response that is abolished when the transduction channels are blocked. The active forces generated by the bundles are sufficient to move the overlying membrane.

Impact of renal medullary three-dimensional architecture on oxygen transport.

PubMed

Fry, Brendan C; Edwards, Aurélie; Sgouralis, Ioannis; Layton, Anita T

2014-08-01

We have developed a highly detailed mathematical model of solute transport in the renal medulla of the rat kidney to study the impact of the structured organization of nephrons and vessels revealed in anatomic studies. The model represents the arrangement of tubules around a vascular bundle in the outer medulla and around a collecting duct cluster in the upper inner medulla. Model simulations yield marked gradients in intrabundle and interbundle interstitial fluid oxygen tension (PO2), NaCl concentration, and osmolality in the outer medulla, owing to the vigorous active reabsorption of NaCl by the thick ascending limbs. In the inner medulla, where the thin ascending limbs do not mediate significant active NaCl transport, interstitial fluid composition becomes much more homogeneous with respect to NaCl, urea, and osmolality. Nonetheless, a substantial PO2 gradient remains, owing to the relatively high oxygen demand of the inner medullary collecting ducts. Perhaps more importantly, the model predicts that in the absence of the three-dimensional medullary architecture, oxygen delivery to the inner medulla would drastically decrease, with the terminal inner medulla nearly completely deprived of oxygen. Thus model results suggest that the functional role of the three-dimensional medullary architecture may be to preserve oxygen delivery to the papilla. Additionally, a simulation that represents low medullary blood flow suggests that the separation of thick limbs from the vascular bundles substantially increases the risk of the segments to hypoxic injury. When nephrons and vessels are more homogeneously distributed, luminal PO2 in the thick ascending limb of superficial nephrons increases by 66% in the inner stripe. Furthermore, simulations predict that owing to the Bohr effect, the presumed greater acidity of blood in the interbundle regions, where thick ascending limbs are located, relative to that in the vascular bundles, facilitates the delivery of O2 to support the high metabolic requirements of the thick limbs and raises NaCl reabsorption. Copyright © 2014 the American Physiological Society.

Transduction channels’ gating can control friction on vibrating hair-cell bundles in the ear

PubMed Central

Bormuth, Volker; Barral, Jérémie; Joanny, Jean-François; Jülicher, Frank; Martin, Pascal

2014-01-01

Hearing starts when sound-evoked mechanical vibrations of the hair-cell bundle activate mechanosensitive ion channels, giving birth to an electrical signal. As for any mechanical system, friction impedes movements of the hair bundle and thus constrains the sensitivity and frequency selectivity of auditory transduction. Friction is generally thought to result mainly from viscous drag by the surrounding fluid. We demonstrate here that the opening and closing of the transduction channels produce internal frictional forces that can dominate viscous drag on the micrometer-sized hair bundle. We characterized friction by analyzing hysteresis in the force–displacement relation of single hair-cell bundles in response to periodic triangular stimuli. For bundle velocities high enough to outrun adaptation, we found that frictional forces were maximal within the narrow region of deflections that elicited significant channel gating, plummeted upon application of a channel blocker, and displayed a sublinear growth for increasing bundle velocity. At low velocity, the slope of the relation between the frictional force and velocity was nearly fivefold larger than the hydrodynamic friction coefficient that was measured when the transduction machinery was decoupled from bundle motion by severing tip links. A theoretical analysis reveals that channel friction arises from coupling the dynamics of the conformational change associated with channel gating to tip-link tension. Varying channel properties affects friction, with faster channels producing smaller friction. We propose that this intrinsic source of friction may contribute to the process that sets the hair cell’s characteristic frequency of responsiveness. PMID:24799674

High-order synchronization of hair cell bundles

NASA Astrophysics Data System (ADS)

Levy, Michael; Molzon, Adrian; Lee, Jae-Hyun; Kim, Ji-Wook; Cheon, Jinwoo; Bozovic, Dolores

2016-12-01

Auditory and vestibular hair cell bundles exhibit active mechanical oscillations at natural frequencies that are typically lower than the detection range of the corresponding end organs. We explore how these noisy nonlinear oscillators mode-lock to frequencies higher than their internal clocks. A nanomagnetic technique is used to stimulate the bundles without an imposed mechanical load. The evoked response shows regimes of high-order mode-locking. Exploring a broad range of stimulus frequencies and intensities, we observe regions of high-order synchronization, analogous to Arnold Tongues in dynamical systems literature. Significant areas of overlap occur between synchronization regimes, with the bundle intermittently flickering between different winding numbers. We demonstrate how an ensemble of these noisy spontaneous oscillators could be entrained to efficiently detect signals significantly above the characteristic frequencies of the individual cells.

High-order synchronization of hair cell bundles

PubMed Central

Levy, Michael; Molzon, Adrian; Lee, Jae-Hyun; Kim, Ji-wook; Cheon, Jinwoo; Bozovic, Dolores

2016-01-01

Auditory and vestibular hair cell bundles exhibit active mechanical oscillations at natural frequencies that are typically lower than the detection range of the corresponding end organs. We explore how these noisy nonlinear oscillators mode-lock to frequencies higher than their internal clocks. A nanomagnetic technique is used to stimulate the bundles without an imposed mechanical load. The evoked response shows regimes of high-order mode-locking. Exploring a broad range of stimulus frequencies and intensities, we observe regions of high-order synchronization, analogous to Arnold Tongues in dynamical systems literature. Significant areas of overlap occur between synchronization regimes, with the bundle intermittently flickering between different winding numbers. We demonstrate how an ensemble of these noisy spontaneous oscillators could be entrained to efficiently detect signals significantly above the characteristic frequencies of the individual cells. PMID:27974743

Mammalian Auditory Hair Cell Bundle Stiffness Affects Frequency Tuning by Increasing Coupling along the Length of the Cochlea.

PubMed

Dewey, James B; Xia, Anping; Müller, Ulrich; Belyantseva, Inna A; Applegate, Brian E; Oghalai, John S

2018-06-05

The stereociliary bundles of cochlear hair cells convert mechanical vibrations into the electrical signals required for auditory sensation. While the stiffness of the bundles strongly influences mechanotransduction, its influence on the vibratory response of the cochlear partition is unclear. To assess this, we measured cochlear vibrations in mutant mice with reduced bundle stiffness or with a tectorial membrane (TM) that is detached from the sensory epithelium. We found that reducing bundle stiffness decreased the high-frequency extent and sharpened the tuning of vibratory responses obtained postmortem. Detaching the TM further reduced the high-frequency extent of the vibrations but also lowered the partition's resonant frequency. Together, these results demonstrate that the bundle's stiffness and attachment to the TM contribute to passive longitudinal coupling in the cochlea. We conclude that the stereociliary bundles and TM interact to facilitate passive-wave propagation to more apical locations, possibly enhancing active-wave amplification in vivo. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

Plant 115-kDa actin-filament bundling protein, P-115-ABP, is a homologue of plant villin and is widely distributed in cells.

PubMed

Yokota, Etsuo; Vidali, Luis; Tominaga, Motoki; Tahara, Hiroshi; Orii, Hidefumi; Morizane, Yosuke; Hepler, Peter K; Shimmen, Teruo

2003-10-01

In many cases, actin filaments are arranged into bundles and serve as tracks for cytoplasmic streaming in plant cells. We have isolated an actin-filament bundling protein, which is composed of 115-kDa polypeptide (P-115-ABP), from the germinating pollen of lily, Lilium longiflorum [Nakayasu et al. (1998) BIOCHEM: Biophys. Res. Commun. 249: 61]. P-115-ABP shared similar antigenicity with a plant 135-kDa actin-filament bundling protein (P-135-ABP), a plant homologue of villin. A full-length cDNA clone (ABP115; accession no. AB097407) was isolated from an expression cDNA library of lily pollen by immuno-screening using antisera against P-115-ABP and P-135-ABP. The amino acid sequence of P-115-ABP deduced from this clone showed high homology with those of P-135-ABP and four villin isoforms of Arabidopsis thaliana (AtVLN1, AtVLN2, AtVLN3 and AtVLN4), especially AtVLN4, indicating that P-115-ABP can also be classified as a plant villin. The P-115-ABP isolated biochemically from the germinating lily pollen was able to arrange F-actin filaments with uniform polarity into bundles and this bundling activity was suppressed by Ca2+-calmodulin (CaM), similar to the actin-filament bundling properties of P-135-ABP. The P-115-ABP type of plant villin was widely distributed in plant cells, from algae to land plants. In root hair cells of Hydrocharis dubia, this type of plant villin was co-localized with actin-filament bundles in the transvacuolar strands and the sub-cortical regions. Microinjection of the antiserum against P-115-ABP into living root hair cells caused the disappearance of transvaculor strands and alteration of the route of cytoplasmic streaming. In internodal cells of Chara corallina in which the P-135-ABP type of plant villin is lacking, the P-115-ABP type showed co-localization with actin-filament cables anchored on the intracellular surface of chloroplasts. These results indicated that plant villins are widely distributed and involved in the organization of actin filaments into bundles throughout the plant kingdom.

Hair cell regeneration in the bullfrog vestibular otolith organs following aminoglycoside toxicity

NASA Technical Reports Server (NTRS)

Baird, R. A.; Torres, M. A.; Schuff, N. R.

1993-01-01

Adult bullfrog were given single intraotic injections of the aminoglycoside antibiotic gentamicin sulfate and sacrificed at postinjection times ranging from 0.5 to 9 days. The saccular and utricular maculae of normal and injected animals were examined in wholemount and cross-section. Intraotic 200 microM gentamicin concentrations resulted in the uniform destruction of the hair bundles and, at later times, the cell bodies of saccular hair cells. In the utriculus, striolar hair cells were selectively damaged while extrastriolar hair cells were relatively unaffected. Regenerating hair cells, identified in sectioned material by their small cell bodies and short, well-formed hair bundles, were seen in the saccular and utricular maculae as early as 24-48 h postinjection. Immature versions of mature hair cell types in both otolith organs were recognized by the presence or absence of a bulbed kinocilia and the relative lengths of their kinocilia and longest stereocilia. Utricular hair cell types with kinocilia longer than their longest stereocilia were observed at earlier than hair cell types with shorter kinocilia. In the sacculus, the hair bundles of gentamicin-treated animals, even at 9 days postinjection, were significantly smaller than those of normal animals. The hair bundles of utricular hair cells, on the other hand, reached full maturity within the same time period.

Hair cell regeneration in the bullfrog vestibular otolith organs following aminoglycoside toxicity

NASA Technical Reports Server (NTRS)

Baird, Richard A.; Torres, M. A.; Schuff, N. R.

1994-01-01

Adult bullfrogs were given single intraotic injections of the aminoglycoside antibiotic gentamicin sulfate and sacrificed at postinjection times ranging from 0.5 to 9 days. The saccular and utricular maculae of normal and injected animals were examined in wholemount and cross-section. Intraotic 200 (mu) M gentamicin concentrations resulted in the uniform destruction of the hair bundles and, at later times, the cell bodies of saccular hair cells. In the utriculus, striolar hair cells were selectively damaged while extrastriolar hair cells were relatively unaffected. Regenerating hair cells, identified in sectioned material by their small cell bodies and short, well-formed hair bundles, were seen in the saccular and utricular maculae as early as 24-48 h postinjection. Immature versions of mature hair cell types in both otolith organs were recognized by the presence of absence of a bulbed kinocilia and the relative lengths of their kinocilia and longest sterocilia. Utricular hair cell types with kinocilia longer than their longest stereocilia were observed at earlier times than hair cell types with shorter kinocilia. In the same sacculus, the hair bundles of gentamicin-treated animals, even at 9 days postinjection, were significantly smaller than those of normal animals. The hair bundles of utricular hair cells, on the other hand, reached full maturity within the same time period.

Movement of protein and macromolecules between host plants and the parasitic weed Phelipanche aegyptiaca Pers.

PubMed

Aly, Radi; Hamamouch, Noureddine; Abu-Nassar, Jacklin; Wolf, Shmuel; Joel, Daniel M; Eizenberg, Hanan; Kaisler, Efrat; Cramer, Carole; Gal-On, Amit; Westwood, James H

2011-12-01

Little is known about the translocation of proteins and other macromolecules from a host plant to the parasitic weed Phelipanche spp. Long-distance movement of proteins between host and parasite was explored using transgenic tomato plants expressing green fluorescent protein (GFP) in their companion cells. We further used fluorescent probes of differing molecular weights to trace vascular continuity between the host plant and the parasite. Accumulation of GFP was observed in the central vascular bundle of leaves and in the root phloem of transgenic tomato plants expressing GFP under the regulation of AtSUC2 promoter. When transgenic tomato plants expressing GFP were parasitized with P. aegyptiaca, extensive GFP was translocated from the host phloem to the parasite phloem and accumulated in both Phelipanche tubercles and shoots. No movement of GFP to the parasite was observed when tobacco plants expressing GFP targeted to the ER were parasitized with P. aegyptiaca. Experiments using fluorescent probes of differing molecular weights to trace vascular continuity between the host plant and the parasite demonstrated that Phelipanche absorbs dextrans up to 70 kDa in size from the host and that this movement can be bi-directional. In the present study, we prove for the first time delivery of proteins from host to the parasitic weed P. aegyptiaca via phloem connections, providing information for developing parasite resistance strategies.

Increased dermal collagen bundle alignment in systemic sclerosis is associated with a cell migration signature and role of Arhgdib in directed fibroblast migration on aligned ECMs

PubMed Central

Lafyatis, Robert; Burkly, Linda C.

2017-01-01

Systemic sclerosis (SSc) is a devastating disease affecting the skin and internal organs. Dermal fibrosis manifests early and Modified Rodnan Skin Scores (MRSS) correlate with disease progression. Transcriptomics of SSc skin biopsies suggest the role of the in vivo microenvironment in maintaining the pathological myofibroblasts. Therefore, defining the structural changes in dermal collagen in SSc patients could inform our understanding of fibrosis pathogenesis. Here, we report a method for quantitative whole-slide image analysis of dermal collagen from SSc patients, and our findings of more aligned dermal collagen bundles in diffuse cutaneous SSc (dcSSc) patients. Using the bleomycin-induced mouse model of SSc, we identified a distinct high dermal collagen bundle alignment gene signature, characterized by a concerted upregulation in cell migration, adhesion, and guidance pathways, and downregulation of spindle, replication, and cytokinesis pathways. Furthermore, increased bundle alignment induced a cell migration gene signature in fibroblasts in vitro, and these cells demonstrated increased directed migration on aligned ECM fibers that is dependent on expression of Arhgdib (Rho GDP-dissociation inhibitor 2). Our results indicate that increased cell migration is a cellular response to the increased collagen bundle alignment featured in fibrotic skin. Moreover, many of the cell migration genes identified in our study are shared with human SSc skin and may be new targets for therapeutic intervention. PMID:28662216

A Model for Amplification of Hair-Bundle Motion by Cyclical Binding of Ca2+ to Mechanoelectrical-Transduction Channels

NASA Astrophysics Data System (ADS)

Choe, Yong; Magnasco, Marcelo O.; Hudspeth, A. J.

1998-12-01

Amplification of auditory stimuli by hair cells augments the sensitivity of the vertebrate inner ear. Cell-body contractions of outer hair cells are thought to mediate amplification in the mammalian cochlea. In vertebrates that lack these cells, and perhaps in mammals as well, active movements of hair bundles may underlie amplification. We have evaluated a mathematical model in which amplification stems from the activity of mechanoelectrical-transduction channels. The intracellular binding of Ca2+ to channels is posited to promote their closure, which increases the tension in gating springs and exerts a negative force on the hair bundle. By enhancing bundle motion, this force partially compensates for viscous damping by cochlear fluids. Linear stability analysis of a six-state kinetic model reveals Hopf bifurcations for parameter values in the physiological range. These bifurcations signal conditions under which the system's behavior changes from a damped oscillatory response to spontaneous limit-cycle oscillation. By varying the number of stereocilia in a bundle and the rate constant for Ca2+ binding, we calculate bifurcation frequencies spanning the observed range of auditory sensitivity for a representative receptor organ, the chicken's cochlea. Simulations using prebifurcation parameter values demonstrate frequency-selective amplification with a striking compressive nonlinearity. Because transduction channels occur universally in hair cells, this active-channel model describes a mechanism of auditory amplification potentially applicable across species and hair-cell types.

Viral and Cellular Factors Involved in Phloem Transport of Plant Viruses

PubMed Central

Hipper, Clémence; Brault, Véronique; Ziegler-Graff, Véronique; Revers, Frédéric

2013-01-01

Phloem transport of plant viruses is an essential step in the setting-up of a complete infection of a host plant. After an initial replication step in the first cells, viruses spread from cell-to-cell through mesophyll cells, until they reach the vasculature where they rapidly move to distant sites in order to establish the infection of the whole plant. This last step is referred to as systemic transport, or long-distance movement, and involves virus crossings through several cellular barriers: bundle sheath, vascular parenchyma, and companion cells for virus loading into sieve elements (SE). Viruses are then passively transported within the source-to-sink flow of photoassimilates and are unloaded from SE into sink tissues. However, the molecular mechanisms governing virus long-distance movement are far from being understood. While most viruses seem to move systemically as virus particles, some viruses are transported in SE as viral ribonucleoprotein complexes (RNP). The nature of the cellular and viral factors constituting these RNPs is still poorly known. The topic of this review will mainly focus on the host and viral factors that facilitate or restrict virus long-distance movement. PMID:23745125

Testing for Starch, Respiring Tissues, and Vascular Bundles: Inquiry-Based Seed and Stem Anatomy Labs.

ERIC Educational Resources Information Center

Florine, Sara; Hammond, Paul; Pomart, Katrina; Balschweid, Mark

2002-01-01

Describes some inquiry-based labs in which students identify starch in popped popcorn, then determine whether starch is present in the kernels prior to them being cooked. Students distinguish monocot and dicot stems as well as determining whether boiling kills tissues in seeds that have been soaked in water. (DDR)

First report of ratoon stunt of sugarcane caused by Leifsonia xyl. subsp. xyli in Pakistan

USDA-ARS?s Scientific Manuscript database

During a survey of the sugarcane crop in the area of Faisalabad, Sargodha and the Dera Ghazi Khan Division of the Punjab province of Pakistan from 2007 to 2010, symptoms consistent with ratoon stunting, including stunted growth and reddening of the vascular bundles at the nodal regions were observed...

Association of red coloration with senescence of sugar maple leaves in autumn

Treesearch

P.G. Schaberg; P.F. Murakami; M.R. Turner; H.K. Heitz; G.J. Hawley

2008-01-01

We evaluated the association of red coloration with senescence in sugar maple (Acer saccharum Marsh.) leaves by assessing differences in leaf retention strength and the progression of the abscission layer through the vascular bundle of green, yellow, and red leaves of 14 mature open-grown trees in October 2002. Computer image analysis confirmed...

Zebrafish Models for the Mechanosensory Hair Cell Dysfunction in Usher Syndrome 3 Reveal That Clarin-1 Is an Essential Hair Bundle Protein.

PubMed

Gopal, Suhasini R; Chen, Daniel H-C; Chou, Shih-Wei; Zang, Jingjing; Neuhauss, Stephan C F; Stepanyan, Ruben; McDermott, Brian M; Alagramam, Kumar N

2015-07-15

Usher syndrome type III (USH3) is characterized by progressive loss of hearing and vision, and varying degrees of vestibular dysfunction. It is caused by mutations that affect the human clarin-1 protein (hCLRN1), a member of the tetraspanin protein family. The missense mutation CLRN1(N48K), which affects a conserved N-glycosylation site in hCLRN1, is a common causative USH3 mutation among Ashkenazi Jews. The affected individuals hear at birth but lose that function over time. Here, we developed an animal model system using zebrafish transgenesis and gene targeting to provide an explanation for this phenotype. Immunolabeling demonstrated that Clrn1 localized to the hair cell bundles (hair bundles). The clrn1 mutants generated by zinc finger nucleases displayed aberrant hair bundle morphology with diminished function. Two transgenic zebrafish that express either hCLRN1 or hCLRN1(N48K) in hair cells were produced to examine the subcellular localization patterns of wild-type and mutant human proteins. hCLRN1 localized to the hair bundles similarly to zebrafish Clrn1; in contrast, hCLRN1(N48K) largely mislocalized to the cell body with a small amount reaching the hair bundle. We propose that this small amount of hCLRN1(N48K) in the hair bundle provides clarin-1-mediated function during the early stages of life; however, the presence of hCLRN1(N48K) in the hair bundle diminishes over time because of intracellular degradation of the mutant protein, leading to progressive loss of hair bundle integrity and hair cell function. These findings and genetic tools provide an understanding and path forward to identify therapies to mitigate hearing loss linked to the CLRN1 mutation. Mutations in the clarin-1 gene affect eye and ear function in humans. Individuals with the CLRN1(N48K) mutation are born able to hear but lose that function over time. Here, we develop an animal model system using zebrafish transgenesis and gene targeting to provide an explanation for this phenotype. This approach illuminates the role of clarin-1 and the molecular mechanism linked to the CLRN1(N48K) mutation in sensory hair cells of the inner ear. Additionally, the investigation provided an in vivo model to guide future drug discovery to rescue the hCLRN1(N48K) in hair cells. Copyright © 2015 the authors 0270-6474/15/3510188-14$15.00/0.

A macroscopic scale model of bacterial flagellar bundling

NASA Astrophysics Data System (ADS)

Kim, Munju; Bird, James C.; van Parys, Annemarie J.; Breuer, Kenneth S.; Powers, Thomas R.

2003-12-01

Escherichia coli and other bacteria use rotating helical filaments to swim. Each cell typically has about four filaments, which bundle or disperse depending on the sense of motor rotation. To study the bundling process, we built a macroscopic scale model consisting of stepper motor-driven polymer helices in a tank filled with a high-viscosity silicone oil. The Reynolds number, the ratio of viscous to elastic stresses, and the helix geometry of our experimental model approximately match the corresponding quantities of the full-scale E. coli cells. We analyze digital video images of the rotating helices to show that the initial rate of bundling is proportional to the motor frequency and is independent of the characteristic relaxation time of the filament. We also determine which combinations of helix handedness and sense of motor rotation lead to bundling.

Purification and Properties of Mesophyll and Bundle Sheath Cell α-Glucan Phosphorylases from Zea mays L. 1

PubMed Central

Mateyka, Christian; Schnarrenberger, Claus

1988-01-01

Two major α-glucan phosphorylases (I and II) from leaves of the C4 plant corn (Zea mays L.) were previously shown to be compartmented in mesophyll and bundle sheath cells, respectively (C Mateyka, C Schnarrenberger 1984 Plant Sci Lett 36: 119-123). The two enzymes were separated by chromatography on DEAE-cellulose and purified to homogeneity by affinity chromatography on immobilized starch, according to published procedures, as developed for the cytosol and chloroplast phosphorylase from the C3 plant spinach. The two α-glucan phosphorylases have their pH optimum at pH 7. The specificity for polyglucans was similar for soluble starch and amylopectin, however, differed for glycogen (Km = 16 micrograms per milliliter for the mesophyll cell and 250 micrograms per milliliter for the bundle sheath cell phosphorylase). Maltose, maltotriose, and maltotetraose were not cleaved by either phosphorylase. If maltopentaose was used as substrate, the rate was about twice as high with the bundle sheath cell phosphorylase, than with the mesophyll cell phosphorylase. The phosphorylase I showed a molecular mass of 174 kilodaltons and the phosphorylase II of 195 kilodaltons for the native enzyme and of 87 and of 53 kilodaltons for the SDS-treated proteins, respectively. Specific antisera raised against mesophyll cell phosphorylase from corn leaves and against chloroplast phosphorylase from spinach leaves implied high similarity for the cytosol phosphorylase of the C3 plant spinach with mesophyll cell phosphorylase of the C4 plant corn and of chloroplast phosphorylase of spinach with the bundle sheath cell phosphorylase of corn. Images Fig. 2 Fig. 7 PMID:16665923

Spatial imaging and speciation of Cu in rice (Oryza sativa L.) roots using synchrotron-based X-ray microfluorescence and X-ray absorption spectroscopy.

PubMed

Lu, Lingli; Xie, Ruohan; Liu, Ting; Wang, Haixing; Hou, Dandi; Du, Yonghua; He, Zhenli; Yang, Xiaoe; Sun, Hui; Tian, Shengke

2017-05-01

Knowledge of elemental localization and speciation in rice (Oryza sativa L.) roots is crucial for elucidating the mechanisms of Cu accumulation so as to facilitate the development of strategies to inhibit Cu accumulation in rice grain grown in contaminated soils. Using synchrotron-based X-ray microfluorescence and X-ray absorption spectroscopy, we investigated the distribution patterns and speciation of Cu in rice roots treated with 50 μM Cu for 7 days. A clear preferential localization of Cu in the meristematic zone was observed in root tips as compared with the elongation zone. Investigation of Cu in the root cross sections revealed that the intensity of Cu in the vascular bundles was more than 10-fold higher than that in the other scanned sites (epidermis and cortex) in rice roots. The dominant chemical form of Cu (79.1%) in rice roots was similar to that in the Cu-cell wall compounds. These results suggest that although Cu can be easily transported into the vascular tissues in rice roots, most of the metal absorbed by plants is retained in the roots owing to its high binding to the cell wall compounds, thus preventing metal translocation to the aerial parts of the plants. Copyright © 2017 Elsevier Ltd. All rights reserved.

[The structure of vegetative organs, and saponins histochemical localization and content comparization in Polygala sibirica L].

PubMed

Teng, Hong Mei; Fang, Min Feng; Hu, Zheng Hai

2009-02-01

Anatomical, histochemical and phytochemistry methods were used to investigate the structure of vegetative organs, and saponins localization and dynamic changes in Polygala sibirica L. The root consisted of developed periderm and secondary vascular. The secondary phloem was thick, and mainly composed of parenchyma. There were well-developed vessels and fibers in the secondary xylem. The stem was composed of epidermis, cortex and vascular bundle. The ring of sclerenchymatous cells lied between cortex and phloem might be the apoplastic protective screen which could protect the stem from drought. The leaf was bifacial one. The root and stem possessed characteristics adapting to arid environment. Histochemical localization results showed that saponins distributed in secondary phloem and phelloderm of root, in epidermis, cortex and phloem of stem, mainly in mesophyll of leaf. It displayed that saponins accumulated mainly in parenchyma cells of vegetative organs, among of which, the secondary phloem was the main storage site. The HPLC results also showed that the saponins accumulated in all the vegetative organs of Polygala sibirica L., with higher content in roots and lower content in the aerial part that included stems and leaves. The study indicated the aerial part of Polygala sibirica L. also had medicinal value. The saponins content had dynamic variance at the developmental stage, the crude drug should be gathered at period from April to May.

Spatial confinement of active microtubule networks induces large-scale rotational cytoplasmic flow

PubMed Central

Suzuki, Kazuya; Miyazaki, Makito; Takagi, Jun; Itabashi, Takeshi; Ishiwata, Shin’ichi

2017-01-01

Collective behaviors of motile units through hydrodynamic interactions induce directed fluid flow on a larger length scale than individual units. In cells, active cytoskeletal systems composed of polar filaments and molecular motors drive fluid flow, a process known as cytoplasmic streaming. The motor-driven elongation of microtubule bundles generates turbulent-like flow in purified systems; however, it remains unclear whether and how microtubule bundles induce large-scale directed flow like the cytoplasmic streaming observed in cells. Here, we adopted Xenopus egg extracts as a model system of the cytoplasm and found that microtubule bundle elongation induces directed flow for which the length scale and timescale depend on the existence of geometrical constraints. At the lower activity of dynein, kinesins bundle and slide microtubules, organizing extensile microtubule bundles. In bulk extracts, the extensile bundles connected with each other and formed a random network, and vortex flows with a length scale comparable to the bundle length continually emerged and persisted for 1 min at multiple places. When the extracts were encapsulated in droplets, the extensile bundles pushed the droplet boundary. This pushing force initiated symmetry breaking of the randomly oriented bundle network, leading to bundles aligning into a rotating vortex structure. This vortex induced rotational cytoplasmic flows on the length scale and timescale that were 10- to 100-fold longer than the vortex flows emerging in bulk extracts. Our results suggest that microtubule systems use not only hydrodynamic interactions but also mechanical interactions to induce large-scale temporally stable cytoplasmic flow. PMID:28265076

A new Late Devonian genus with seed plant affinities.

PubMed

Wang, Deming; Liu, Le

2015-02-26

Many ovules of Late Devonian (Famennian) seed plants have been well studied. However, because few taxa occur with anatomically preserved stems and/or petioles, the vascular system of these earliest spermatophytes is little understood and available data come mostly from Euramerica. There remains great controversy over the anatomical differentiation of Late Devonian and Carboniferous seed plant groups of Buteoxylonales, Calamopityales and Lyginopteridales. Protostele evolution of these early spermatophytes needs more research. A new taxon Yiduxylon trilobum gen. et sp. nov. with seed plant affinities has been discovered in the Upper Devonian (Famennian) Tizikou Formation of Hubei Province, China. It is represented by stems, helically arranged and bifurcate fronds with two orders of pinnae and planate pinnules. Both secondary pinnae and pinnules are borne alternately. Stems contain a small protostele with three primary xylem ribs possessing a single peripheral protoxylem strand. Thick secondary xylem displays multiseriate bordered pitting on the tangential and radial walls of the tracheids, and has biseriate to multiseriate and high rays. A narrow cortex consists of inner cortex without sclerotic nests and sparganum-type outer cortex with peripheral bands of vertically aligned sclerenchyma cells. Two leaf traces successively arise tangentially from each primary xylem rib and they divide once to produce four circular-oval traces in the stem cortex. Four vascular bundles occur in two C-shaped groups at each petiole base with ground tissue and peripheral bands of sclerenchyma cells. Yiduxylon justifies the assignment to a new genus mainly because of the protostele with protoxylem strands only near the periphery of primary xylem ribs, leaf trace origination and petiolar vascular supply structure. It shares many definitive characters with Calamopityales and Lyginopteridales, further underscoring the anatomical similarities among early seed plants. The primary vascular system, pycnoxylic-manoxylic secondary xylem with bordered pits on both tangential and radial walls of a tracheid and leaf trace divergence of Yiduxylon suggest transitional features between the early spermatophytes and ancestral aneurophyte progymnosperms.

Microanalysis of plant cell wall polysaccharides.

PubMed

Obel, Nicolai; Erben, Veronika; Schwarz, Tatjana; Kühnel, Stefan; Fodor, Andrea; Pauly, Markus

2009-09-01

Oligosaccharide Mass Profiling (OLIMP) allows a fast and sensitive assessment of cell wall polymer structure when coupled with Matrix Assisted Laser Desorption Ionisation Time Of Flight Mass Spectrometry (MALDI-TOF MS). The short time required for sample preparation and analysis makes possible the study of a wide range of plant organs, revealing a high degree of heterogeneity in the substitution pattern of wall polymers such as the cross-linking glycan xyloglucan and the pectic polysaccharide homogalacturonan. The high sensitivity of MALDI-TOF allows the use of small amounts of samples, thus making it possible to investigate the wall structure of single cell types when material is collected by such methods as laser micro-dissection. As an example, the analysis of the xyloglucan structure in the leaf cell types outer epidermis layer, entire epidermis cell layer, palisade mesophyll cells, and vascular bundles were investigated. OLIMP is amenable to in situ wall analysis, where wall polymers are analyzed on unprepared plant tissue itself without first isolating cell walls. In addition, OLIMP enables analysis of wall polymers in Golgi-enriched fractions, the location of nascent matrix polysaccharide biosynthesis, enabling separation of the processes of wall biosynthesis versus post-deposition apoplastic metabolism. These new tools will make possible a semi-quantitative analysis of the cell wall at an unprecedented level.

Magnetic actuation of hair cells

NASA Astrophysics Data System (ADS)

Rowland, David; Roongthumskul, Yuttana; Lee, Jae-Hyun; Cheon, Jinwoo; Bozovic, Dolores

2011-11-01

The bullfrog sacculus contains mechanically sensitive hair cells whose stereociliary bundles oscillate spontaneously when decoupled from the overlying membrane. Steady-state offsets on the resting position of a hair bundle can suppress or modulate this native motility. To probe the dynamics of spontaneous oscillation in the proximity of the critical point, we describe here a method for mechanical actuation that avoids loading the bundles or contributing to the viscous drag. Magnetite beads were attached to the tips of the stereocilia, and a magnetic probe was used to impose deflections. This technique allowed us to observe the transition from multi-mode to single-mode state in freely oscillating bundles, as well as the crossover from the oscillatory to the quiescent state.

Electrolytic/fuel cell bundles and systems including a current collector in communication with an electrode thereof

DOEpatents

Hawkes, Grant L.; Herring, James S.; Stoots, Carl M.; O& #x27; Brien, James E.

2013-03-05

Electrolytic/fuel cell bundles and systems including such bundles include an electrically conductive current collector in communication with an anode or a cathode of each of a plurality of cells. A cross-sectional area of the current collector may vary in a direction generally parallel to a general direction of current flow through the current collector. The current collector may include a porous monolithic structure. At least one cell of the plurality of cells may include a current collector that surrounds an outer electrode of the cell and has at least six substantially planar exterior surfaces. The planar surfaces may extend along a length of the cell, and may abut against a substantially planar surface of a current collector of an adjacent cell. Methods for generating electricity and for performing electrolysis include flowing current through a conductive current collector having a varying cross-sectional area.

Characterization of active hair-bundle motility by a mechanical-load clamp

NASA Astrophysics Data System (ADS)

Salvi, Joshua D.; Maoiléidigh, Dáibhid Ó.; Fabella, Brian A.; Tobin, Mélanie; Hudspeth, A. J.

2015-12-01

Active hair-bundle motility endows hair cells with several traits that augment auditory stimuli. The activity of a hair bundle might be controlled by adjusting its mechanical properties. Indeed, the mechanical properties of bundles vary between different organisms and along the tonotopic axis of a single auditory organ. Motivated by these biological differences and a dynamical model of hair-bundle motility, we explore how adjusting the mass, drag, stiffness, and offset force applied to a bundle control its dynamics and response to external perturbations. Utilizing a mechanical-load clamp, we systematically mapped the two-dimensional state diagram of a hair bundle. The clamp system used a real-time processor to tightly control each of the virtual mechanical elements. Increasing the stiffness of a hair bundle advances its operating point from a spontaneously oscillating regime into a quiescent regime. As predicted by a dynamical model of hair-bundle mechanics, this boundary constitutes a Hopf bifurcation.

Synthetic peptides that cause F-actin bundling and block actin depolymerization

DOEpatents

Sederoff, Heike [Raleigh, NC; Huber, Steven C [Savoy, IL; Larabell, Carolyn A [Berkeley, CA

2011-10-18

Synthetic peptides derived from sucrose synthase, and having homology to actin and actin-related proteins, sharing a common motif, useful for causing acting bundling and preventing actin depolymerization. Peptides exhibiting the common motif are described, as well as specific synthetic peptides which caused bundled actin and inhibit actin depolymerization. These peptides can be useful for treating a subject suffering from a disease characterized by cells having neoplastic growth, for anti-cancer therapeutics, delivered to subjects solely, or concomitantly or sequentially with other known cancer therapeutics. These peptides can also be used for stabilizing microfilaments in living cells and inhibiting growth of cells.

Elevated temperature triggers human respiratory syncytial virus F protein six-helix bundle formation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yunus, Abdul S.; Jackson, Trent P.; Crisafi, Katherine

2010-01-20

Human respiratory syncytial virus (RSV) is a major cause of severe lower respiratory tract infection in infants, immunocompromised patients, and the elderly. The RSV fusion (F) protein mediates fusion of the viral envelope with the target cell membrane during virus entry and is a primary target for antiviral drug and vaccine development. The F protein contains two heptad repeat regions, HR1 and HR2. Peptides corresponding to these regions form a six-helix bundle structure that is thought to play a critical role in membrane fusion. However, characterization of six-helix bundle formation in native RSV F protein has been hindered by themore » fact that a trigger for F protein conformational change has yet to be identified. Here we demonstrate that RSV F protein on the surface of infected cells undergoes a conformational change following exposure to elevated temperature, resulting in the formation of the six-helix bundle structure. We first generated and characterized six-helix bundle-specific antibodies raised against recombinant peptides modeling the RSV F protein six-helix bundle structure. We then used these antibodies as probes to monitor RSV F protein six-helix bundle formation in response to a diverse array of potential triggers of conformational changes. We found that exposure of 'membrane-anchored' RSV F protein to elevated temperature (45-55 deg. C) was sufficient to trigger six-helix bundle formation. Antibody binding to the six-helix bundle conformation was detected by both flow cytometry and cell-surface immunoprecipitation of the RSV F protein. None of the other treatments, including interaction with a number of potential receptors, resulted in significant binding by six-helix bundle-specific antibodies. We conclude that native, untriggered RSV F protein exists in a metastable state that can be converted in vitro to the more stable, fusogenic six-helix bundle conformation by an increase in thermal energy. These findings help to better define the mechanism of RSV F-mediated membrane fusion and have important implications for the identification of therapeutic strategies and vaccines targeting RSV F protein conformational changes.« less

Estimating biozone hydraulic conductivity in wastewater soil-infiltration systems using inverse numerical modeling.

PubMed

Bumgarner, Johnathan R; McCray, John E

2007-06-01

During operation of an onsite wastewater treatment system, a low-permeability biozone develops at the infiltrative surface (IS) during application of wastewater to soil. Inverse numerical-model simulations were used to estimate the biozone saturated hydraulic conductivity (K(biozone)) under variably saturated conditions for 29 wastewater infiltration test cells installed in a sandy loam field soil. Test cells employed two loading rates (4 and 8cm/day) and 3 IS designs: open chamber, gravel, and synthetic bundles. The ratio of K(biozone) to the saturated hydraulic conductivity of the natural soil (K(s)) was used to quantify the reductions in the IS hydraulic conductivity. A smaller value of K(biozone)/K(s,) reflects a greater reduction in hydraulic conductivity. The IS hydraulic conductivity was reduced by 1-3 orders of magnitude. The reduction in IS hydraulic conductivity was primarily influenced by wastewater loading rate and IS type and not by the K(s) of the native soil. The higher loading rate yielded greater reductions in IS hydraulic conductivity than the lower loading rate for bundle and gravel cells, but the difference was not statistically significant for chamber cells. Bundle and gravel cells exhibited a greater reduction in IS hydraulic conductivity than chamber cells at the higher loading rates, while the difference between gravel and bundle systems was not statistically significant. At the lower rate, bundle cells exhibited generally lower K(biozone)/K(s) values, but not at a statistically significant level, while gravel and chamber cells were statistically similar. Gravel cells exhibited the greatest variability in measured values, which may complicate design efforts based on K(biozone) evaluations for these systems. These results suggest that chamber systems may provide for a more robust design, particularly for high or variable wastewater infiltration rates.

Coupling and Elastic Loading Affect the Active Response by the Inner Ear Hair Cell Bundles

PubMed Central

Strimbu, Clark Elliott; Fredrickson-Hemsing, Lea; Bozovic, Dolores

2012-01-01

Active hair bundle motility has been proposed to underlie the amplification mechanism in the auditory endorgans of non-mammals and in the vestibular systems of all vertebrates, and to constitute a crucial component of cochlear amplification in mammals. We used semi-intact in vitro preparations of the bullfrog sacculus to study the effects of elastic mechanical loading on both natively coupled and freely oscillating hair bundles. For the latter, we attached glass fibers of different stiffness to the stereocilia and observed the induced changes in the spontaneous bundle movement. When driven with sinusoidal deflections, hair bundles displayed phase-locked response indicative of an Arnold Tongue, with the frequency selectivity highest at low amplitudes and decreasing under stronger stimulation. A striking broadening of the mode-locked response was seen with increasing stiffness of the load, until approximate impedance matching, where the phase-locked response remained flat over the physiological range of frequencies. When the otolithic membrane was left intact atop the preparation, the natural loading of the bundles likewise decreased their frequency selectivity with respect to that observed in freely oscillating bundles. To probe for signatures of the active process under natural loading and coupling conditions, we applied transient mechanical stimuli to the otolithic membrane. Following the pulses, the underlying bundles displayed active movement in the opposite direction, analogous to the twitches observed in individual cells. Tracking features in the otolithic membrane indicated that it moved in phase with the bundles. Hence, synchronous active motility evoked in the system of coupled hair bundles by external input is sufficient to displace large overlying structures. PMID:22479461

[Morphological and cytohistological observations of seed germination and protocorm development of Bletilla striata].

PubMed

Nie, Ning; Zhu, Yan; Tian, Mei; Hua, Jing-Wen; Wang, Long; Qin, Min-Jian

2016-04-01

In order to investigate the mechanism of growth for Bletilla striata, which could be applied for rapid propagation, morphological and cytohistological of seed germination and protocorm development in vitro culture were observed using paraffin section techniques. In this study, we have found that the development of B. striata goes through four stages： embryo, protocorm, rhizome and pseudobulb. The end away from embryo suspensor is able to differentiate green buds after the seed of B. striata swelling, growing point. At the same time, the other end of embryo grows many white villous roots, with the green bud differentiating into cotyledon, the embryo breaking through seed coat and being protocorm. The shoot apical meristem of protocorm consists of tunica, corpus and leaf primordium, whose developmental flowing tunica-corpus theory. After more vascular bundle appeared from the leaf primordium, B. striata grows into the stage of rhizome. While in the stage of rhizome, the root primordium of tissue culture seedlings are differentia initially that derived from rhizome vascular bundle, belonging to internal origin. Subsequently, the pseudobulb forms by the inner meristem growing into mature parenchymatous tissue and the rhizome enlargement gradually. Copyright© by the Chinese Pharmaceutical Association.

Actin filament bundling by fimbrin is important for endocytosis, cytokinesis, and polarization in fission yeast.

PubMed

Skau, Colleen T; Courson, David S; Bestul, Andrew J; Winkelman, Jonathan D; Rock, Ronald S; Sirotkin, Vladimir; Kovar, David R

2011-07-29

Through the coordinated action of diverse actin-binding proteins, cells simultaneously assemble actin filaments with distinct architectures and dynamics to drive different processes. Actin filament cross-linking proteins organize filaments into higher order networks, although the requirement of cross-linking activity in cells has largely been assumed rather than directly tested. Fission yeast Schizosaccharomyces pombe assembles actin into three discrete structures: endocytic actin patches, polarizing actin cables, and the cytokinetic contractile ring. The fission yeast filament cross-linker fimbrin Fim1 primarily localizes to Arp2/3 complex-nucleated branched filaments of the actin patch and by a lesser amount to bundles of linear antiparallel filaments in the contractile ring. It is unclear whether Fim1 associates with bundles of parallel filaments in actin cables. We previously discovered that a principal role of Fim1 is to control localization of tropomyosin Cdc8, thereby facilitating cofilin-mediated filament turnover. Therefore, we hypothesized that the bundling ability of Fim1 is dispensable for actin patches but is important for the contractile ring and possibly actin cables. By directly visualizing actin filament assembly using total internal reflection fluorescence microscopy, we determined that Fim1 bundles filaments in both parallel and antiparallel orientations and efficiently bundles Arp2/3 complex-branched filaments in the absence but not the presence of actin capping protein. Examination of cells exclusively expressing a truncated version of Fim1 that can bind but not bundle actin filaments revealed that bundling activity of Fim1 is in fact important for all three actin structures. Therefore, fimbrin Fim1 has diverse roles as both a filament "gatekeeper" and as a filament cross-linker.

Structural development of wheat nutrient transfer tissues and their relationships with filial tissues development.

PubMed

Xurun, Yu; Xinyu, Chen; Liang, Zhou; Jing, Zhang; Heng, Yu; Shanshan, Shao; Fei, Xiong; Zhong, Wang

2015-03-01

Nutrients from spikelet phloem are commonly delivered to endosperm via caryopsis nutrient transfer tissues (NTTs). Elucidation of NTTs development is paramount to developing an understanding of the control of assimilate partitioning. Little information was available on the structural development of the entire NTTs and their functions, particularly those involved in the relationship between development of NTTs and growth of filial tissues including endosperm and embryo. In this study, wheat caryopses at different development stages were collected for observation of the NTTs by light microscopy, stereoscopic microscopy, and scanning electron microscopy. The cytological features of NTTs in the developing wheat caryopsis were clearly elucidated. The results were as follows: NTTs in the wheat caryopsis include maternal transfer tissues that are composed of vascular bundle, chalaza and nucellar projection transfer cells, and endosperm transfer tissues that consist of the aleurone transfer cells, starchy endosperm transfer cells, and endosperm conducting cells. The initiation, development, and apoptosis of these NTTs revealed the pattern of temporal and spatial gradient and were closely coordinated with endosperm and embryo development. These results may give us a further understanding about the functions of NTTs and their relationships with endosperm and embryo development.

Prefabrication of axial vascularized tissue engineering coral bone by an arteriovenous loop: a better model.

PubMed

Dong, Qing-shan; Shang, Hong-tao; Wu, Wei; Chen, Fu-lin; Zhang, Jun-rui; Guo, Jia-ping; Mao, Tian-qiu

2012-08-01

The most important problem for the survival of thick 3-dimensional tissues is the lack of vascularization in the context of bone tissue engineering. In this study, a modified arteriovenous loop (AVL) was developed to prefabricate an axial vascularized tissue engineering coral bone in rabbit, with comparison of the arteriovenous bundle (AVB) model. An arteriovenous fistula between rabbit femoral artery and vein was anastomosed to form an AVL. It was placed in a circular side groove of the coral block. The complex was wrapped with an expanded-polytetrafluoroethylene membrane and implanted beneath inguinal skin. After 2, 4, 6 and 8 weeks, the degree of vascularization was evaluated by India ink perfusion, histological examination, vascular casts, and scanning electron microscopy images of vascular endangium. Newly formed fibrous tissues and vasculature extended over the surfaces and invaded the interspaces of entire coral block. The new blood vessels robustly sprouted from the AVL. Those invaginated cavities in the vascular endangium from scanning electron microscopy indicated vessel's sprouted pores. Above indexes in AVL model are all superior to that in AVB model, indicating that the modified AVL model could more effectively develop vascularization in larger tissue engineering bone. Copyright © 2012 Elsevier B.V. All rights reserved.

Plant-based torsional actuator with memory

Treesearch

Nayomi Plaza; Samuel L. Zelinka; Don S. Stone; Joseph E. Jakes

2013-01-01

A bundle of a few loblolly pine (Pinus taeda) cells are moisture-activated torsional actuators that twist multiple revolutions per cm length in direct proportion to moisture content. The bundles generate 10 N m kg􀀀1 specific torque during both twisting and untwisting, which is higher than an electric motor. Additionally, the bundles exhibit a moisture-...

Differential Protein Composition and Gene Expression in Leaf Mesophyll Cells and Bundle Sheath Cells of the C(4) Plant Digitaria sanguinalis (L.) Scop.

PubMed

Potter, J W; Black, C C

1982-08-01

The distribution and molecular weights of cellular proteins in soluble and membrane-associated locations were analyzed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Coomassie blue staining of leaf (Digitaria sanguinalis L. Scop.) extracts and isolated cell extracts. Leaf polypeptides also were pulse-labeled, followed by isolation of the labeled leaf cell types and analysis of the newly synthesized polypeptides in each cell type by electrophoresis and fluorography.Comparison of the electrophoretic patterns of crabgrass whole leaf polypeptides with isolated cell-type polypeptides indicated a difference in protein distribution patterns for the two cell types. The mesophyll cells exhibited a greater allocation of total cellular protein into membrane-associated proteins relative to soluble proteins. In contrast, the bundle sheath cells exhibited a higher percentage of total cellular protein in soluble proteins. Phosphoenolpyruvate carboxylase was the major soluble protein in the mesophyll cell and ribulose bisphosphate carboxylase was the major soluble protein in the bundle sheath cell. The majority of in vivo(35)S-pulse-labeled proteins synthesized by the two crabgrass cell types corresponded in molecular weight to the proteins present in the cell types which were detected by conventional staining techniques. The bundle sheath cell and mesophyll cell fluorograph profiles each had 15 major (35)S-labeled proteins. The major incorporation of (35)S by bundle sheath cells was into products which co-electrophoresed with the large and small subunits of ribulose bisphosphate carboxylase. In contrast, a major (35)S-labeled product in mesophyll cell extracts co-electrophoresed with the subunit of phosphoenolpyruvate carboxylase. Both cell types exhibited equivalent in vivo labeling of a polypeptide with one- and two-dimensional electrophoretic behavior similar to the major apoprotein of the light-harvesting chlorophyll a/b protein. Results from the use of protein synthesis inhibitors during pulse-labeling experiments indicated intercellular differences in both organelle and cytoplasmic protein synthesis. A majority of the (35)S incorporation by crabgrass mesophyll cell 70S ribosomes was associated with a pair of membrane-associated polypeptides of molecular weight 32,000 and 34,500; a comparison of fluorograph and stained gel profiles suggests these products resemble the precursor and mature forms of the maize chloroplast 32,000 dalton protein reported by Grebanier et al. (1978 J. Cell Biol. 28:734-746). In contrast, crabgrass bundle sheath cell organelle translation was directed predominantly into a product which co-electrophoresed with the large subunit of ribulose bisphosphate carboxylase.

Overexpression of OsEXPA8, a Root-Specific Gene, Improves Rice Growth and Root System Architecture by Facilitating Cell Extension

PubMed Central

Ma, Nana; Wang, Ying; Qiu, Shichun; Kang, Zhenhui; Che, Shugang; Wang, Guixue; Huang, Junli

2013-01-01

Expansins are unique plant cell wall proteins that are involved in cell wall modifications underlying many plant developmental processes. In this work, we investigated the possible biological role of the root-specific α-expansin gene OsEXPA8 in rice growth and development by generating transgenic plants. Overexpression of OsEXPA8 in rice plants yielded pleiotropic phenotypes of improved root system architecture (longer primary roots, more lateral roots and root hairs), increased plant height, enhanced leaf number and enlarged leaf size. Further study indicated that the average cell length in both leaf and root vascular bundles was enhanced, and the cell growth in suspension cultures was increased, which revealed the cellular basis for OsEXPA8-mediated rice plant growth acceleration. Expansins are thought to be a key factor required for cell enlargement and wall loosening. Atomic force microscopy (AFM) technology revealed that average wall stiffness values for 35S::OsEXPA8 transgenic suspension-cultured cells decreased over six-fold compared to wild-type counterparts during different growth phases. Moreover, a prominent change in the wall polymer composition of suspension cells was observed, and Fourier-transform infrared (FTIR) spectra revealed a relative increase in the ratios of the polysaccharide/lignin content in cell wall compositions of OsEXPA8 overexpressors. These results support a role for expansins in cell expansion and plant growth. PMID:24124527

Evaluation of the Paratrend Multi-Analyte Sensor for Potential Utilization in Long-Duration Automated Cell Culture Monitoring

NASA Technical Reports Server (NTRS)

Hwang, Emma Y.; Pappas, Dimitri; Jeevarajan, Antony S.; Anderson, Melody M.

2004-01-01

BACKGROUND: Compact and automated sensors are desired for assessing the health of cell cultures in biotechnology experiments. While several single-analyte sensors exist to measure culture health, a multi-analyte sensor would simplify the cell culture system. One such multi-analyte sensor, the Paratrend 7 manufactured by Diametrics Medical, consists of three optical fibers for measuring pH, dissolved carbon dioxide (pCO(2)), dissolved oxygen (pO(2)), and a thermocouple to measure temperature. The sensor bundle was designed for intra-vascular measurements in clinical settings, and can be used in bioreactors operated both on the ground and in NASA's Space Shuttle and International Space Station (ISS) experiments. METHODS: A Paratrend 7 sensor was placed at the outlet of a bioreactor inoculated with BHK-21 (baby hamster kidney) cells. The pH, pCO(2), pO(2), and temperature data were transferred continuously to an external computer. Cell culture medium, manually extracted from the bioreactor through a sampling port, was also assayed using a bench top blood gas analyzer (BGA). RESULTS: Two Paratrend 7 sensors were used over a single cell culture experiment (64 days). When compared to the manually obtained BGA samples, the sensor had good agreement for pH, pCO(2), and pO(2) with bias (and precision) 0.005(0.024), 8.0 mmHg (4.4 mmHg), and 11 mmHg (17 mmHg), respectively for the first two sensors. A third Paratrend sensor (operated for 141 days) had similar agreement (0.02+/-0.15 for pH, -4+/-8 mm Hg for pCO(2), and 24+/-18 mmHg for pO(2)). CONCLUSION: The resulting biases and precisions are com- parable to Paratrend sensor clinical results. Although the pO(2) differences may be acceptable for clinically relevant measurement ranges, the O(2) sensor in this bundle may not be reliable enough for the ranges of pO(2) in these cell culture studies without periodic calibration.

Diffusion and bulk flow in phloem loading: A theoretical analysis of the polymer trap mechanism for sugar transport in plants

NASA Astrophysics Data System (ADS)

Dölger, Julia; Rademaker, Hanna; Liesche, Johannes; Schulz, Alexander; Bohr, Tomas

2014-10-01

Plants create sugar in the mesophyll cells of their leaves by photosynthesis. This sugar, mostly sucrose, has to be loaded via the bundle sheath into the phloem vascular system (the sieve elements), where it is distributed to growing parts of the plant. We analyze the feasibility of a particular loading mechanism, active symplasmic loading, also called the polymer trap mechanism, where sucrose is transformed into heavier sugars, such as raffinose and stachyose, in the intermediary-type companion cells bordering the sieve elements in the minor veins of the phloem. Keeping the heavier sugars from diffusing back requires that the plasmodesmata connecting the bundle sheath with the intermediary cell act as extremely precise filters, which are able to distinguish between molecules that differ by less than 20% in size. In our modeling, we take into account the coupled water and sugar movement across the relevant interfaces, without explicitly considering the chemical reactions transforming the sucrose into the heavier sugars. Based on the available data for plasmodesmata geometry, sugar concentrations, and flux rates, we conclude that this mechanism can in principle function, but that it requires pores of molecular sizes. Comparing with the somewhat uncertain experimental values for sugar export rates, we expect the pores to be only 5%-10% larger than the hydraulic radius of the sucrose molecules. We find that the water flow through the plasmodesmata, which has not been quantified before, contributes only 10%-20% to the sucrose flux into the intermediary cells, while the main part is transported by diffusion. On the other hand, the subsequent sugar translocation into the sieve elements would very likely be carried predominantly by bulk water flow through the plasmodesmata. Thus, in contrast to apoplasmic loaders, all the necessary water for phloem translocation would be supplied in this way with no need for additional water uptake across the plasma membranes of the phloem.

Diffusion and bulk flow in phloem loading: a theoretical analysis of the polymer trap mechanism for sugar transport in plants.

PubMed

Dölger, Julia; Rademaker, Hanna; Liesche, Johannes; Schulz, Alexander; Bohr, Tomas

2014-10-01

Plants create sugar in the mesophyll cells of their leaves by photosynthesis. This sugar, mostly sucrose, has to be loaded via the bundle sheath into the phloem vascular system (the sieve elements), where it is distributed to growing parts of the plant. We analyze the feasibility of a particular loading mechanism, active symplasmic loading, also called the polymer trap mechanism, where sucrose is transformed into heavier sugars, such as raffinose and stachyose, in the intermediary-type companion cells bordering the sieve elements in the minor veins of the phloem. Keeping the heavier sugars from diffusing back requires that the plasmodesmata connecting the bundle sheath with the intermediary cell act as extremely precise filters, which are able to distinguish between molecules that differ by less than 20% in size. In our modeling, we take into account the coupled water and sugar movement across the relevant interfaces, without explicitly considering the chemical reactions transforming the sucrose into the heavier sugars. Based on the available data for plasmodesmata geometry, sugar concentrations, and flux rates, we conclude that this mechanism can in principle function, but that it requires pores of molecular sizes. Comparing with the somewhat uncertain experimental values for sugar export rates, we expect the pores to be only 5%-10% larger than the hydraulic radius of the sucrose molecules. We find that the water flow through the plasmodesmata, which has not been quantified before, contributes only 10%-20% to the sucrose flux into the intermediary cells, while the main part is transported by diffusion. On the other hand, the subsequent sugar translocation into the sieve elements would very likely be carried predominantly by bulk water flow through the plasmodesmata. Thus, in contrast to apoplasmic loaders, all the necessary water for phloem translocation would be supplied in this way with no need for additional water uptake across the plasma membranes of the phloem.

Integration of Tmc1/2 into the mechanotransduction complex in zebrafish hair cells is regulated by Transmembrane O-methyltransferase (Tomt)

PubMed Central

Erickson, Timothy; Morgan, Clive P; Olt, Jennifer; Hardy, Katherine; Busch-Nentwich, Elisabeth; Maeda, Reo; Clemens, Rachel; Krey, Jocelyn F; Nechiporuk, Alex; Barr-Gillespie, Peter G; Marcotti, Walter; Nicolson, Teresa

2017-01-01

Transmembrane O-methyltransferase (TOMT/LRTOMT) is responsible for non-syndromic deafness DFNB63. However, the specific defects that lead to hearing loss have not been described. Using a zebrafish model of DFNB63, we show that the auditory and vestibular phenotypes are due to a lack of mechanotransduction (MET) in Tomt-deficient hair cells. GFP-tagged Tomt is enriched in the Golgi of hair cells, suggesting that Tomt might regulate the trafficking of other MET components to the hair bundle. We found that Tmc1/2 proteins are specifically excluded from the hair bundle in tomt mutants, whereas other MET complex proteins can still localize to the bundle. Furthermore, mouse TOMT and TMC1 can directly interact in HEK 293 cells, and this interaction is modulated by His183 in TOMT. Thus, we propose a model of MET complex assembly where Tomt and the Tmcs interact within the secretory pathway to traffic Tmc proteins to the hair bundle. DOI: http://dx.doi.org/10.7554/eLife.28474.001 PMID:28534737

Symplastic continuity between mesophyll and companion cells in minor veins of mature Cucurbita pepo L. leaves.

PubMed

Turgeon, R; Hepler, P K

1989-08-01

Dye-coupling studies have been undertaken to determine whether plasmodesmata between intermediary cells (companion cells) and bundle-sheath cells in the minor veins of mature Cucurbita pepo L. leaves are open to passage of low-molecular-weight compounds. The abaxial phloem of these veins was exposed by stripping the lower epidermis of the leaf and removing the spongy-mesophyll cells by abrasion. Lucifer yellow, or 6-carboxyfluorescein, were microinjected into intermediary cells by iontophoresis, and dye location was monitored by fluorescence microscopy. Dye spread from one intermediary cell to another and from intermediary cells to bundle-sheath and mesophyll cells. No movement of microinjected dye occurred in some experiments, probably because plasmodesmata closed in response to cell damage incurred during tissue preparation. Most, but not all, minor veins in tissue prepared for microinjections studies are able to accumulate exogenously supplied [(14)C]sucrose. Plasmolysis studies indicate that the solute content of intermediary cells is much higher than that of bundle-sheath cells. In C. pepo, plasmodesmata may provide a route for the selective phloem loading of export sugars.

ACF7 is a hair-bundle antecedent, positioned to integrate cuticular plate actin and somatic tubulin.

PubMed

Antonellis, Patrick J; Pollock, Lana M; Chou, Shih-Wei; Hassan, Ahmed; Geng, Ruishuang; Chen, Xi; Fuchs, Elaine; Alagramam, Kumar N; Auer, Manfred; McDermott, Brian M

2014-01-01

The precise morphology of the mechanosensitive hair bundle requires seamless integration of actin and microtubule networks. Here, we identify Acf7a (actin crosslinking family protein 7a) as a protein positioned to bridge these distinct cytoskeletal networks in hair cells. By imaging Acf7a-Citrine fusion protein in zebrafish and immunolabeling of vestibular and cochlear mouse hair cells, we show that Acf7a and ACF7 circumscribe, underlie, and are interwoven into the cuticular plate (CP), and they also encircle the basal body of the kinocilium. In cochlear hair cells, ACF7 localization is graded, with the highest concentration near each fonticulus--an area free of F-actin in the region of the CP that contains the basal body. During hair-cell development and regeneration, Acf7a precedes formation of the hair bundle and CP. Finally, electron tomography demonstrates that the ends of microtubules insert into the CP and are decorated with filamentous linkers connecting microtubules to the CP. These observations are consistent with ACF7 being a linker protein, which may shape the cytoskeleton of the hair cell early during hair-bundle genesis.

ACF7 Is a Hair-Bundle Antecedent, Positioned to Integrate Cuticular Plate Actin and Somatic Tubulin

PubMed Central

Antonellis, Patrick J.; Pollock, Lana M.; Chou, Shih-Wei; Hassan, Ahmed; Geng, Ruishuang; Chen, Xi; Fuchs, Elaine; Alagramam, Kumar N.; Auer, Manfred

2014-01-01

The precise morphology of the mechanosensitive hair bundle requires seamless integration of actin and microtubule networks. Here, we identify Acf7a (actin crosslinking family protein 7a) as a protein positioned to bridge these distinct cytoskeletal networks in hair cells. By imaging Acf7a–Citrine fusion protein in zebrafish and immunolabeling of vestibular and cochlear mouse hair cells, we show that Acf7a and ACF7 circumscribe, underlie, and are interwoven into the cuticular plate (CP), and they also encircle the basal body of the kinocilium. In cochlear hair cells, ACF7 localization is graded, with the highest concentration near each fonticulus—an area free of F-actin in the region of the CP that contains the basal body. During hair-cell development and regeneration, Acf7a precedes formation of the hair bundle and CP. Finally, electron tomography demonstrates that the ends of microtubules insert into the CP and are decorated with filamentous linkers connecting microtubules to the CP. These observations are consistent with ACF7 being a linker protein, which may shape the cytoskeleton of the hair cell early during hair-bundle genesis. PMID:24381291

Numerically bridging lamellipodial and filopodial activity during cell spreading reveals a potentially novel trigger of focal adhesion maturation.

PubMed

Loosli, Y; Vianay, B; Luginbuehl, R; Snedeker, J G

2012-05-01

We present a novel approach to modeling cell spreading, and use it to reveal a potentially central mechanism regulating focal adhesion maturation in various cell phenotypes. Actin bundles that span neighboring focal complexes at the lamellipodium-lamellum interface were assumed to be loaded by intracellular forces in proportion to bundle length. We hypothesized that the length of an actin bundle (with the corresponding accumulated force at its adhesions) may thus regulate adhesion maturation to ensure cell mechanical stability and morphological integrity. We developed a model to test this hypothesis, implementing a "top-down" approach to simplify certain cellular processes while explicitly incorporating complexity of other key subcellular mechanisms. Filopodial and lamellipodial activities were treated as modular processes with functional spatiotemporal interactions coordinated by rules regarding focal adhesion turnover and actin bundle dynamics. This theoretical framework was able to robustly predict temporal evolution of cell area and cytoskeletal organization as reported from a wide range of cell spreading experiments using micropatterned substrates. We conclude that a geometric/temporal modeling framework can capture the key functional aspects of the rapid spreading phase and resultant cytoskeletal complexity. Hence the model is used to reveal mechanistic insight into basic cell behavior essential for spreading. It demonstrates that actin bundles spanning nascent focal adhesions such that they are aligned to the leading edge may accumulate centripetal endogenous forces along their length, and could thus trigger focal adhesion maturation in a force-length dependent fashion. We suggest that this mechanism could be a central "integrating" factor that effectively coordinates force-mediated adhesion maturation at the lamellipodium-lamellum interface.

A transmission and scanning electron microscopic study of the saccule in five species of catfishes.

PubMed

Jenkins, D B

1979-01-01

The sacculi of five species of catfishes were studied by transmission and scanning electron microscopy. In four species, the sagitta exhibited a multifluted anterior part and a tapered posterior part; in Corydoras aeneus, however, the fluted part was absent, and a vertical component extended dorsally to terminate near the opening of the transverse canal. In all species, the otoliths had a laminar structure. An otolithic membrane was present, and hair cell bundles projected into cavities on the macular surface of the membrane. Attachments of the otolithic membrane to the neuroepithelium included short extensions of the membrane to the tallest components of the hair cell bundles of the peripheral cells and more delicate connections to the kinocilium and taller stereocilia of central cells; in addition, attachments to the microvilli of supporting cells were present. In both hair cells and supporting cells single microtubules and bundles of microtubules were present; the bundles had an orderly arrangement and were associated with cytoplasmic densities surrounding the desmosomes. The hair cells were innervated by both afferent and efferent nerve endings. Studies of the polarization of the hair cells in all species (except C. aeneus) showed that there was a single longitudinal axis that divided dorsally polarized cells from those oriented ventrally. In Doras spinosissimus and Bunocephalus bicolor, an additional line of polarization was evident in a small area in the anterior part of the macula; therefore, in these forms there was a double bipolar orientation.

A two-dimensional microscale model of gas exchange during photosynthesis in maize (Zea mays L.) leaves.

PubMed

Retta, Moges; Ho, Quang Tri; Yin, Xinyou; Verboven, Pieter; Berghuijs, Herman N C; Struik, Paul C; Nicolaï, Bart M

2016-05-01

CO2 exchange in leaves of maize (Zea mays L.) was examined using a microscale model of combined gas diffusion and C4 photosynthesis kinetics at the leaf tissue level. Based on a generalized scheme of photosynthesis in NADP-malic enzyme type C4 plants, the model accounted for CO2 diffusion in a leaf tissue, CO2 hydration and assimilation in mesophyll cells, CO2 release from decarboxylation of C4 acids, CO2 fixation in bundle sheath cells and CO2 retro-diffusion from bundle sheath cells. The transport equations were solved over a realistic 2-D geometry of the Kranz anatomy obtained from light microscopy images. The predicted responses of photosynthesis rate to changes in ambient CO2 and irradiance compared well with those obtained from gas exchange measurements. A sensitivity analysis showed that the CO2 permeability of the mesophyll-bundle sheath and airspace-mesophyll interfaces strongly affected the rate of photosynthesis and bundle sheath conductance. Carbonic anhydrase influenced the rate of photosynthesis, especially at low intercellular CO2 levels. In addition, the suberin layer at the exposed surface of the bundle sheath cells was found beneficial in reducing the retro-diffusion. The model may serve as a tool to investigate CO2 diffusion further in relation to the Kranz anatomy in C4 plants. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

The Competition between Liquid and Vapor Transport in Transpiring Leaves1[W][OPEN

PubMed Central

Rockwell, Fulton Ewing; Holbrook, N. Michele; Stroock, Abraham Duncan

2014-01-01

In leaves, the transpirational flux of water exits the veins as liquid and travels toward the stomata in both the vapor and liquid phases before exiting the leaf as vapor. Yet, whether most of the evaporation occurs from the vascular bundles (perivascular), from the photosynthetic mesophyll cells, or within the vicinity of the stomatal pore (peristomatal) remains in dispute. Here, a one-dimensional model of the competition between liquid and vapor transport is developed from the perspective of nonisothermal coupled heat and water molecule transport in a composite medium of airspace and cells. An analytical solution to the model is found in terms of the energy and transpirational fluxes from the leaf surfaces and the absorbed solar energy load, leading to mathematical expressions for the proportions of evaporation accounted for by the vascular, mesophyll, and epidermal regions. The distribution of evaporation in a given leaf is predicted to be variable, changing with the local environment, and to range from dominantly perivascular to dominantly peristomatal depending on internal leaf architecture, with mesophyll evaporation a subordinate component. Using mature red oak (Quercus rubra) trees, we show that the model can be solved for a specific instance of a transpiring leaf by combining gas-exchange data, anatomical measurements, and hydraulic experiments. We also investigate the effect of radiation load on the control of transpiration, the potential for condensation on the inside of an epidermis, and the impact of vapor transport on the hydraulic efficiency of leaf tissue outside the xylem. PMID:24572172

The competition between liquid and vapor transport in transpiring leaves.

PubMed

Rockwell, Fulton Ewing; Holbrook, N Michele; Stroock, Abraham Duncan

2014-04-01

In leaves, the transpirational flux of water exits the veins as liquid and travels toward the stomata in both the vapor and liquid phases before exiting the leaf as vapor. Yet, whether most of the evaporation occurs from the vascular bundles (perivascular), from the photosynthetic mesophyll cells, or within the vicinity of the stomatal pore (peristomatal) remains in dispute. Here, a one-dimensional model of the competition between liquid and vapor transport is developed from the perspective of nonisothermal coupled heat and water molecule transport in a composite medium of airspace and cells. An analytical solution to the model is found in terms of the energy and transpirational fluxes from the leaf surfaces and the absorbed solar energy load, leading to mathematical expressions for the proportions of evaporation accounted for by the vascular, mesophyll, and epidermal regions. The distribution of evaporation in a given leaf is predicted to be variable, changing with the local environment, and to range from dominantly perivascular to dominantly peristomatal depending on internal leaf architecture, with mesophyll evaporation a subordinate component. Using mature red oak (Quercus rubra) trees, we show that the model can be solved for a specific instance of a transpiring leaf by combining gas-exchange data, anatomical measurements, and hydraulic experiments. We also investigate the effect of radiation load on the control of transpiration, the potential for condensation on the inside of an epidermis, and the impact of vapor transport on the hydraulic efficiency of leaf tissue outside the xylem.

Surface interactions of Fusarium graminearum on barley.

PubMed

Imboden, Lori; Afton, Drew; Trail, Frances

2018-06-01

The filamentous fungus Fusarium graminearum, a devastating pathogen of barley (Hordeum vulgare L.), produces mycotoxins that pose a health hazard. To investigate the surface interactions of F. graminearum on barley, we focused on barley florets, as the most important infection site leading to grain contamination. The fungus interacted with silica-accumulating cells (trichomes and silica/cork cell pairs) on the host surface. We identified variation in trichome-type cells between two-row and six-row barley, and in the role of specific epidermal cells in the ingress of F. graminearum into barley florets. Prickle-type trichomes functioned to trap conidia and were sites of fungal penetration. Infections of more mature florets supported the spread of hyphae into the vascular bundles, whereas younger florets did not show this spread. These differences related directly to the timing and location of increases in silica content during maturation. Focal accumulation of cellulose in infected paleae of two-row and six-row barley indicated that the response is in part linked to trichome type. Overall, silica-accumulating epidermal cells had an expanded role in barley, serving to trap conidia, provide sites for fungal ingress and initiate resistance responses, suggesting a role for silica in pathogen establishment. © 2017 BSPP AND JOHN WILEY & SONS LTD.

From Biological Cilia to Artificial Flow Sensors: Biomimetic Soft Polymer Nanosensors with High Sensing Performance

NASA Astrophysics Data System (ADS)

Asadnia, Mohsen; Kottapalli, Ajay Giri Prakash; Karavitaki, K. Domenica; Warkiani, Majid Ebrahimi; Miao, Jianmin; Corey, David P.; Triantafyllou, Michael

2016-09-01

We report the development of a new class of miniature all-polymer flow sensors that closely mimic the intricate morphology of the mechanosensory ciliary bundles in biological hair cells. An artificial ciliary bundle is achieved by fabricating bundled polydimethylsiloxane (PDMS) micro-pillars with graded heights and electrospinning polyvinylidenefluoride (PVDF) piezoelectric nanofiber tip links. The piezoelectric nature of a single nanofiber tip link is confirmed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Rheology and nanoindentation experiments are used to ensure that the viscous properties of the hyaluronic acid (HA)-based hydrogel are close to the biological cupula. A dome-shaped HA hydrogel cupula that encapsulates the artificial hair cell bundle is formed through precision drop-casting and swelling processes. Fluid drag force actuates the hydrogel cupula and deflects the micro-pillar bundle, stretching the nanofibers and generating electric charges. Functioning with principles analogous to the hair bundles, the sensors achieve a sensitivity and threshold detection limit of 300 mV/(m/s) and 8 μm/s, respectively. These self-powered, sensitive, flexible, biocompatibale and miniaturized sensors can find extensive applications in navigation and maneuvering of underwater robots, artificial hearing systems, biomedical and microfluidic devices.

From Biological Cilia to Artificial Flow Sensors: Biomimetic Soft Polymer Nanosensors with High Sensing Performance.

PubMed

Asadnia, Mohsen; Kottapalli, Ajay Giri Prakash; Karavitaki, K Domenica; Warkiani, Majid Ebrahimi; Miao, Jianmin; Corey, David P; Triantafyllou, Michael

2016-09-13

We report the development of a new class of miniature all-polymer flow sensors that closely mimic the intricate morphology of the mechanosensory ciliary bundles in biological hair cells. An artificial ciliary bundle is achieved by fabricating bundled polydimethylsiloxane (PDMS) micro-pillars with graded heights and electrospinning polyvinylidenefluoride (PVDF) piezoelectric nanofiber tip links. The piezoelectric nature of a single nanofiber tip link is confirmed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Rheology and nanoindentation experiments are used to ensure that the viscous properties of the hyaluronic acid (HA)-based hydrogel are close to the biological cupula. A dome-shaped HA hydrogel cupula that encapsulates the artificial hair cell bundle is formed through precision drop-casting and swelling processes. Fluid drag force actuates the hydrogel cupula and deflects the micro-pillar bundle, stretching the nanofibers and generating electric charges. Functioning with principles analogous to the hair bundles, the sensors achieve a sensitivity and threshold detection limit of 300 mV/(m/s) and 8 μm/s, respectively. These self-powered, sensitive, flexible, biocompatibale and miniaturized sensors can find extensive applications in navigation and maneuvering of underwater robots, artificial hearing systems, biomedical and microfluidic devices.

Bundling of elastic filaments induced by hydrodynamic interactions

NASA Astrophysics Data System (ADS)

Man, Yi; Page, William; Poole, Robert J.; Lauga, Eric

2017-12-01

Peritrichous bacteria swim in viscous fluids by rotating multiple helical flagellar filaments. As the bacterium swims forward, all its flagella rotate in synchrony behind the cell in a tight helical bundle. When the bacterium changes its direction, the flagellar filaments unbundle and randomly reorient the cell for a short period of time before returning to their bundled state and resuming swimming. This rapid bundling and unbundling is, at its heart, a mechanical process whereby hydrodynamic interactions balance with elasticity to determine the time-varying deformation of the filaments. Inspired by this biophysical problem, we present in this paper what is perhaps the simplest model of bundling whereby two or more straight elastic filaments immersed in a viscous fluid rotate about their centerline, inducing rotational flows which tend to bend the filaments around each other. We derive an integrodifferential equation governing the shape of the filaments resulting from mechanical balance in a viscous fluid at low Reynolds number. We show that such equation may be evaluated asymptotically analytically in the long-wavelength limit, leading to a local partial differential equation governed by a single dimensionless bundling number. A numerical study of the dynamics predicted by the model reveals the presence of two configuration instabilities with increasing bundling numbers: first to a crossing state where filaments touch at one point and then to a bundled state where filaments wrap along each other in a helical fashion. We also consider the case of multiple filaments and the unbundling dynamics. We next provide an intuitive physical model for the crossing instability and show that it may be used to predict analytically its threshold and adapted to address the transition to a bundling state. We then use a macroscale experimental implementation of the two-filament configuration in order to validate our theoretical predictions and obtain excellent agreement. This long-wavelength model of bundling will be applicable to other problems in biological physics and provides the groundwork for further, more realistic, models of flagellar bundling.

[Histological structure of the trabecular meshwork in the eyeball: challenging the traditional concept and preliminary findings in rabbits, rats and mice].

PubMed

Shi, Yun; Zhou, Fan-Qi; Luo, Zhou-Cai; Chen, Ying-Hua; Chen, Yu; Dong, Wei-Ren

2017-10-20

To verify that the trabecular meshwork (TM) in the wall of the eyeball consists of smooth muscle fibers instead of collagen fibers or endothelial cells. Eighteen fresh eyeballs from 3 rabbits, 3 SD rats and 3 mice were sectioned along the sagittal plane and sliced after paraffin embedding for HE staining, VG staining, Masson staining, α-SMA immunohistochemistry or CD31 immunohistochemistry. These slices were observed under microscope and the structure of the TM was compared with those of scleral collagen fibers, ciliary muscles and endothelial cells. HE staining of the eyeball slices from the 3 animal species resulted in purplish red staining of the TM, which was highly consistent with ciliary muscle fibers. The cell?like structures on the surface of the TM were not clearly outlined, with flat nuclei showing a dark purple staining; these structures did not show obvious boundaries from the TM. Ciliary muscle fibers, which were smooth muscle cells in nature, were aligned in bundles in various directions. The longitudinally sectioned cells were flat and contained purplish cytoplasm and highly flattened nuclei. Scleral collagen fibers were stained dark red with a few fibroblasts sandwiched among them. The long axis of the fibroblasts was in parallel with that of the collagen fibers. The outline of the fibroblast was not clear and the nucleus was flat in dark blue. The vascular endothelial cells presented with different morphologies and contained light purplish cytoplasm and dark nuclei, protruding into the vascular cavity. VG staining of the TM revealed a pale red filamentous structure, and the collagen fibers were stained bright red. Masson staining of the TM showed a reticular structure consisting mainly of dark red fibers intermingled with thin green fibers. Scleral collagen fibers presented with a cord?like green wavy structure. The endothelial cells were green and flat, while the ciliary smooth muscle fibers were purple. In immunohistochemistry for α?SMA, the TM and the ciliary smooth muscle fibers showed a strong positivity in the cytoplasm, while the scleral collagen fibers and vascular endothelial cells showed negative staining; immunohistochemistry for CD31 showed no obvious positive staining in the TM, collagen fibers or ciliary smooth muscle cells from all the animals in spite of slight differences among them. The TM consists mainly of smooth muscle fibers with a thin layer of peripheral endomysium without endothelial cells.

Xylem Development in Prunus Flower Buds and the Relationship to Deep Supercooling

PubMed Central

Ashworth, Edward N.

1984-01-01

Xylem development in eight Prunus species was examined and the relationship to deep supercooling assessed. Dormant buds of six species, P. armeniaca, P. avium, P. cerasus, P. persica, P. salicina, and P. sargentii deep supercooled. Xylem vessel elements were not observed within the dormant floral primordia of these species. Instead, discrete bundles containing procambial cells were observed. Vascular differentiation resumed and xylem continuity was established during the time that the capacity to deep supercool was lost. In P. serotina and P. virginiana, two species which do not supercool, xylem vessels ran the length of the inflorescence and presumably provided a conduit for the spread of ice into the bud. The results support the hypothesis that the lack of xylem continuity is an important feature of buds which deep supercool. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 PMID:16663523

A peptide hormone required for Casparian strip diffusion barrier formation in Arabidopsis roots.

PubMed

Nakayama, Takuya; Shinohara, Hidefumi; Tanaka, Mina; Baba, Koki; Ogawa-Ohnishi, Mari; Matsubayashi, Yoshikatsu

2017-01-20

Plants achieve mineral ion homeostasis by means of a hydrophobic barrier on endodermal cells called the Casparian strip, which restricts lateral diffusion of ions between the root vascular bundles and the soil. We identified a family of sulfated peptides required for contiguous Casparian strip formation in Arabidopsis roots. These peptide hormones, which we named Casparian strip integrity factor 1 (CIF1) and CIF2, are expressed in the root stele and specifically bind the endodermis-expressed leucine-rich repeat receptor kinase GASSHO1 (GSO1)/SCHENGEN3 and its homolog, GSO2. A mutant devoid of CIF peptides is defective in ion homeostasis in the xylem. CIF genes are environmentally responsive. Casparian strip regulation is not merely a passive process driven by root developmental cues; it also serves as an active strategy to cope with adverse soil conditions. Copyright © 2017, American Association for the Advancement of Science.

Perforating and deep lymphatic vessels in the knee region: an anatomical study and clinical implications.

PubMed

Pan, Wei-Ren; Zeng, Fan-Qiang; Wang, De-Guang; Qiu, Zhi-Qiang

2017-05-01

To determine the relationship between the perforating and deep lymphatic vessels in the knee region for clinical implications. Four lower limbs from two unembalmed human cadavers were used. Under a surgical microscope, 6% hydrogen peroxide was employed to detect lymph vessels accompanying the small saphenous vein, anterior tibial, posterior tibial and fibular blood vessels all commencing from distal ends of specimens. Each lymphatic vessel was inserted by a 30-gauge needle and injected with a barium sulphate mixture. Each specimen was dissected, radiographed and photographed to determine the perforating and deep lymphatic vessels in the region. A perforating lymph vessel was observed in the popliteal fossa of each specimen. It arose from the superficial popliteal lymph node and terminated in the deep popliteal lymph node. The anterior tibial, posterior tibial and peroneal lymph vessels were discovered in the region travelling with the corresponding vascular bundles. After penetrating the vascular aperture of the interosseous membrane between the tibia and fibula, the anterior tibial lymph vessel entered directly into the deep popliteal lymph node or converged to either the posterior tibial or fibular lymph vessel, before entering the node. The posterior tibial and peroneal lymph vessels entered the deep popliteal lymph node. The efferent lymph vessel of the deep popliteal lymph node travelled with the femoral vascular bundle. The perforating and deep lymphatic vessels in the knee region has been presented and discussed. The information advances our anatomical knowledge and the results will benefit clinical management. © 2017 Royal Australasian College of Surgeons.

Mechanical properties and cellular response of novel electrospun nanofibers for ligament tissue engineering: Effects of orientation and geometry.

PubMed

Pauly, Hannah M; Kelly, Daniel J; Popat, Ketul C; Trujillo, Nathan A; Dunne, Nicholas J; McCarthy, Helen O; Haut Donahue, Tammy L

2016-08-01

Electrospun nanofibers are a promising material for ligamentous tissue engineering, however weak mechanical properties of fibers to date have limited their clinical usage. The goal of this work was to modify electrospun nanofibers to create a robust structure that mimics the complex hierarchy of native tendons and ligaments. The scaffolds that were fabricated in this study consisted of either random or aligned nanofibers in flat sheets or rolled nanofiber bundles that mimic the size scale of fascicle units in primarily tensile load bearing soft musculoskeletal tissues. Altering nanofiber orientation and geometry significantly affected mechanical properties; most notably aligned nanofiber sheets had the greatest modulus; 125% higher than that of random nanofiber sheets; and 45% higher than aligned nanofiber bundles. Modifying aligned nanofiber sheets to form aligned nanofiber bundles also resulted in approximately 107% higher yield stresses and 140% higher yield strains. The mechanical properties of aligned nanofiber bundles were in the range of the mechanical properties of the native ACL: modulus=158±32MPa, yield stress=57±23MPa and yield strain=0.38±0.08. Adipose derived stem cells cultured on all surfaces remained viable and proliferated extensively over a 7 day culture period and cells elongated on nanofiber bundles. The results of the study suggest that aligned nanofiber bundles may be useful for ligament and tendon tissue engineering based on their mechanical properties and ability to support cell adhesion, proliferation, and elongation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Signal detection by active, noisy hair bundles

NASA Astrophysics Data System (ADS)

O'Maoiléidigh, Dáibhid; Salvi, Joshua D.; Hudspeth, A. J.

2018-05-01

Vertebrate ears employ hair bundles to transduce mechanical movements into electrical signals, but their performance is limited by noise. Hair bundles are substantially more sensitive to periodic stimulation when they are mechanically active, however, than when they are passive. We developed a model of active hair-bundle mechanics that predicts the conditions under which a bundle is most sensitive to periodic stimulation. The model relies only on the existence of mechanotransduction channels and an active adaptation mechanism that recloses the channels. For a frequency-detuned stimulus, a noisy hair bundle's phase-locked response and degree of entrainment as well as its detection bandwidth are maximized when the bundle exhibits low-amplitude spontaneous oscillations. The phase-locked response and entrainment of a bundle are predicted to peak as functions of the noise level. We confirmed several of these predictions experimentally by periodically forcing hair bundles held near the onset of self-oscillation. A hair bundle's active process amplifies the stimulus preferentially over the noise, allowing the bundle to detect periodic forces less than 1 pN in amplitude. Moreover, the addition of noise can improve a bundle's ability to detect the stimulus. Although, mechanical activity has not yet been observed in mammalian hair bundles, a related model predicts that active but quiescent bundles can oscillate spontaneously when they are loaded by a sufficiently massive object such as the tectorial membrane. Overall, this work indicates that auditory systems rely on active elements, composed of hair cells and their mechanical environment, that operate on the brink of self-oscillation.

P protein in the phloem of Cucurbita. II. The P protein of mature sieve elements.

PubMed

Cronshaw, J; Esau, K

1968-08-01

During maturation of sieve elements in Cucurbita maxima Duchesne, the P-protein bodies (slime bodies) usually disperse in the tonoplast-free cell. In some sieve elements the P-protein bodies fail to disperse. The occurrence of dispersal or nondispersal of P-protein bodies can be related to the position of the sieve elements in the stem or petiole. In the sieve elements within the vascular bundle the bodies normally disperse; in the extrafascicular sieve elements the bodies often fail to disperse. Extrafascicular sieve elements showing partial dispersal also occur. The appearance of the sieve plate in fixed material is related to the degree of dispersal or nondispersal of the P-protein bodies. In sieve elements in which complete dispersal occurs the sieve plate usually has a substantial deposit of callose, and the sieve-plate pores are filled with P protein. In sieve elements containing nondispersing P-protein bodies the sieve plate bears little or no callose, and its pores usually are essentially "open." The dispersed P-protein components may aggregate into loosely organized "strands," which sometimes extend vertically through the cell and continue through the sieve-plate pores; but they may be oriented otherwise in the cell, even transversely.

The organization of the actin cytoskeleton in vertical and graviresponding primary roots of maize

NASA Technical Reports Server (NTRS)

Blancaflor, E. B.; Hasenstein, K. H.

1997-01-01

To determine whether actin microfilament (MF) organization is correlated with differential elongation, primary roots of Zea mays cv Merit maintained vertically or reoriented horizontally for 15 to 120 min were stained with rhodamine phalloidin and examined with a confocal microscope. Root curvature was measured with a computer-controlled video digitizer. In vertical roots bundles of MFs in the elongation and maturation zone were oriented parallel to the longitudinal axis of cells. MFs in the vascular parenchyma cells were more abundant than in the cortex and epidermis. Epidermal and proendodermal cells in the meristematic region contained transverse cortical MFs. The organization of MFs of graviresponding roots was similar to that of vertical roots. Application of cytochalasin B or cytochalasin D resulted in extensive disruption of MFs in the cortex and epidermis, but only partially affected MFs in the stele. Despite the cytochalasin B-induced depolymerization of MFs, gravicurvature exceeded that of controls. In contrast, the auxin transport inhibitor N-1 naphthylphthalamic acid suppressed root curvature but had no observable effect on the integrity of the MFs. The data indicate that MFs may not be involved in the graviresponse of maize roots.

P PROTEIN IN THE PHLOEM OF CUCURBITA

PubMed Central

Cronshaw, James; Esau, Katherine

1968-01-01

During maturation of sieve elements in Cucurbita maxima Duchesne, the P-protein bodies (slime bodies) usually disperse in the tonoplast-free cell. In some sieve elements the P-protein bodies fail to disperse. The occurrence of dispersal or nondispersal of P-protein bodies can be related to the position of the sieve elements in the stem or petiole. In the sieve elements within the vascular bundle the bodies normally disperse; in the extrafascicular sieve elements the bodies often fail to disperse. Extrafascicular sieve elements showing partial dispersal also occur. The appearance of the sieve plate in fixed material is related to the degree of dispersal or nondispersal of the P-protein bodies. In sieve elements in which complete dispersal occurs the sieve plate usually has a substantial deposit of callose, and the sieve-plate pores are filled with P protein. In sieve elements containing nondispersing P-protein bodies the sieve plate bears little or no callose, and its pores usually are essentially "open." The dispersed P-protein components may aggregate into loosely organized "strands," which sometimes extend vertically through the cell and continue through the sieve-plate pores; but they may be oriented otherwise in the cell, even transversely. PMID:5664205

An operating principle of the turtle utricle to detect wide dynamic range.

PubMed

Nam, Jong-Hoon

2018-03-01

The utricle encodes both static information such as head orientation, and dynamic information such as vibrations. It is not well understood how the utricle can encode both static and dynamic information for a wide dynamic range (from <0.05 to >2 times the gravitational acceleration; from DC to > 1000 Hz vibrations). Using computational models of the hair cells in the turtle utricle, this study presents an explanation on how the turtle utricle encodes stimulations over such a wide dynamic range. Two hair bundles were modeled using the finite element method-one representing the striolar hair cell (Cell S), and the other representing the medial extrastriolar hair cell (Cell E). A mechano-transduction (MET) channel model was incorporated to compute MET current (i MET ) due to hair bundle deflection. A macro-mechanical model of the utricle was used to compute otoconial motions from head accelerations (a Head ). According to known anatomical data, Cell E has a long kinocilium that is embedded into the stiff otoconial layer. Unlike Cell E, the hair bundle of Cell S falls short of the otoconial layer. Considering such difference in the mechanical connectivity between the hair cell bundle and the otoconial layer, three cases were simulated: Cell E displacement-clamped, Cell S viscously-coupled, and Cell S displacement-clamped. Head accelerations at different amplitude levels and different frequencies were simulated for the three cases. When a realistic head motion was simulated, Cell E was responsive to head orientation, while the viscously-coupled Cell S was responsive to fast head motion imitating the feeding strike of a turtle. Copyright © 2017 Elsevier B.V. All rights reserved.

The acquisition of mechano-electrical transducer current adaptation in auditory hair cells requires myosin VI.

PubMed

Marcotti, Walter; Corns, Laura F; Goodyear, Richard J; Rzadzinska, Agnieszka K; Avraham, Karen B; Steel, Karen P; Richardson, Guy P; Kros, Corné J

2016-07-01

The transduction of sound into electrical signals occurs at the hair bundles atop sensory hair cells in the cochlea, by means of mechanosensitive ion channels, the mechano-electrical transducer (MET) channels. The MET currents decline during steady stimuli; this is termed adaptation and ensures they always work within the most sensitive part of their operating range, responding best to rapidly changing (sound) stimuli. In this study we used a mouse model (Snell's waltzer) for hereditary deafness in humans that has a mutation in the gene encoding an unconventional myosin, myosin VI, which is present in the hair bundles. We found that in the absence of myosin VI the MET current fails to acquire its characteristic adaptation as the hair bundles develop. We propose that myosin VI supports the acquisition of adaptation by removing key molecules from the hair bundle that serve a temporary, developmental role. Mutations in Myo6, the gene encoding the (F-actin) minus end-directed unconventional myosin, myosin VI, cause hereditary deafness in mice (Snell's waltzer) and humans. In the sensory hair cells of the cochlea, myosin VI is expressed in the cell bodies and along the stereocilia that project from the cells' apical surface. It is required for maintaining the structural integrity of the mechanosensitive hair bundles formed by the stereocilia. In this study we investigate whether myosin VI contributes to mechano-electrical transduction. We report that Ca(2+) -dependent adaptation of the mechano-electrical transducer (MET) current, which serves to keep the transduction apparatus operating within its most sensitive range, is absent in outer and inner hair cells from homozygous Snell's waltzer mutant mice, which fail to express myosin VI. The operating range of the MET channels is also abnormal in the mutants, resulting in the absence of a resting MET current. We found that cadherin 23, a component of the hair bundle's transient lateral links, fails to be downregulated along the length of the stereocilia in maturing Myo6 mutant mice. MET currents of heterozygous littermates appear normal. We propose that myosin VI, by removing key molecules from developing hair bundles, is required for the development of the MET apparatus and its Ca(2+) -dependent adaptation. © 2016 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.

Magnetic Bead Actuation of Saccular Hair Cells

NASA Astrophysics Data System (ADS)

Rowland, David; Ramunno-Johnson, Damien; Lee, Jae-Hyun; Cheon, Jinwoo; Bozovic, Dolores

2011-11-01

When decoupled from the overlying membrane, hair bundles of the amphibian sacculus exhibit spontaneous oscillation. To explore the dynamics of this innate motility without an imposed external load, we recorded their oscillations with a high-speed CMOS camera, and applied mechanical manipulation that minimally alters the geometry of an individual hair bundle. We present a technique that utilizes micron-sized magnetic particles to actuate the stereociliary bundle with a magnetized probe. Quasi-steady-state displacements were imposed on freely oscillating bundles. Our data indicate that deflection of the bundle affects both the frequency and the amplitude of the oscillations, with a crossing of the bifurcation that is dependent on the direction and speed of the applied offset.

The Use of Quantitative SPECT/CT Imaging to Assess Residual Limb Health

DTIC Science & Technology

2017-10-01

loss in 2020.4 BACKGROUND The integrity of the vasculature, nerves, and soft tissue within the extremities is of high importance, as an impairment or...formation, and vascular abnormalities .6 Therefore, effective diagnosis can be critical in directing the medical treatment of patients. Standard noninva...and identify damage to their nor- mal fasicular pattern, nerve swelling or thickening, loss of nerve bundle integrity , and development of neuromas

[Nitrogen bio-cycle in the alpine tundra ecosystem of Changbai Mountain and its comparison with arctic tundra].

PubMed

Wei, Jing; Zhao, Jing-zhu; Deng, Hong-bing; Wu, Gang; Hao, Ying-jie; Shang, Wen-yan

2005-03-01

The nitrogen bio-cycle was discussed in the alpine tundra ecosystem of Changbai Mountain through compartment model. The alpine tundra of Changbai Mountain was compared with Arctic tundra by the common ratio of genus and species in this paper. It was found that the 89.3% of genus and 58.6% of species was the common between Changbai alpine tundra and Arctic tundra while 95.5% of lichen genus and 58.7% lichen species, 82.1% of moss genus and 76.3% of moss species, 93.1% of vascular bundle genus and 40.5% of vascular bundle species were the common, respectively, which made vegetation type or community to be similar between Changbai alpine tundra and Arctic tundra. The total storage of nitrogen was 65220.6 t in the vegetation-plant system of Changbai Mountain, of which soil pool amounted to 99.3%. The nitrogen storage of each compartment was as follows: the vegetation pool, litterfall pool and soil pool were 237.4 t, 145.3 t and 64837.9 t respectively. The transferable amounts of nitrogen were 131.7 t x a(-1), 58 t/a and 73.7 t x a(-1) in the aboveground plant, belowground root system and litterfall of alpine tundra ecosystem of Changbai Mountain.

Thalamic reticular nucleus in Caiman crocodilus: Relationship with the dorsal thalamus.

PubMed

Pritz, M B

2016-05-13

The thalamic reticular nucleus was investigated in one group of crocodilians, Caiman crocodilus. This neuronal aggregate is composed of two parts: a compact portion and a diffuse region made up of scattered cells within the forebrain bundles. In Caiman, both the lateral and medial forebrain bundles project to the telencephalon and the thalamic reticular nucleus is associated with each fiber tract. In the lateral forebrain bundle, the compact area is termed the nucleus of the dorsal peduncle (dorsal peduncular nucleus) while the diffuse part is called the perireticular area. In the medial forebrain bundle, the interstitial nucleus comprises one part of the compact area while another region without a specific neuronal label is also present. Similar to the perireticular cells of the lateral forebrain bundle, scattered cells are also present in the medial forebrain bundle. Morphological features of the thalamic reticular nucleus are revealed with stains for the following: fibers; cells; succinic acid dehydrogenase; and acetylcholinesterase. Regardless of which dorsal thalamic nucleus was injected, a localized region of the thalamic reticular nucleus contained retrogradely labeled cells and anterogradely labeled axons and terminals. This grouping was termed clusters and was felt to represent the densest interconnection between the dorsal thalamus and the reticular nucleus. Using clusters as an index of interconnections, the reticular nucleus was divided into sectors, each of which was associated with a specific dorsal thalamic nucleus. An organization similar to that found in Caiman is present in other sauropsids as well as in mammals. These data suggest that a thalamic reticular nucleus is present in all amniotes and has morphological properties similar to those described in this analysis. Lastly, a hypothesis is presented to explain how the external shape of the reticular nucleus in Caiman might be transformed into the homologous area in a representative bird and mammal. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

Arabidopsis thaliana plants lacking the ARP2/3 complex show defects in cell wall assembly and auxin distribution.

PubMed

Pratap Sahi, Vaidurya; Cifrová, Petra; García-González, Judith; Kotannal Baby, Innu; Mouillé, Gregory; Gineau, Emilie; Müller, Karel; Baluška, František; Soukup, Aleš; Petrášek, Jan; Schwarzerová, Katerina

2017-12-25

The cytoskeleton plays an important role in the synthesis of plant cell walls. Both microtubules and actin cytoskeleton are known to be involved in the morphogenesis of plant cells through their role in cell wall building. The role of ARP2/3-nucleated actin cytoskeleton in the morphogenesis of cotyledon pavement cells has been described before. Seedlings of Arabidopsis mutants lacking a functional ARP2/3 complex display specific cell wall-associated defects. In three independent Arabidopsis mutant lines lacking subunits of the ARP2/3 complex, phenotypes associated with the loss of the complex were analysed throughout plant development. Organ size and anatomy, cell wall composition, and auxin distribution were investigated. ARP2/3-related phenotype is associated with changes in cell wall composition, and the phenotype is manifested especially in mature tissues. Cell walls of mature plants contain less cellulose and a higher amount of homogalacturonan, and display changes in cell wall lignification. Vascular bundles of mutant inflorescence stems show a changed pattern of AUX1-YFP expression. Plants lacking a functional ARP2/3 complex have decreased basipetal auxin transport. The results suggest that the ARP2/3 complex has a morphogenetic function related to cell wall synthesis and auxin transport. © The Author(s) 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The structure of the conus arteriosus of the sturgeon (Acipenser naccarii) heart: II. The myocardium, the subepicardium, and the conus-aorta transition.

PubMed

Icardo, José M; Colvee, Elvira; Cerra, Maria C; Tota, Bruno

2002-12-01

Sturgeons constitute a family of living "fossil" fish whose heart is related to that of other ancient fish and the elasmobranches. We have undertaken a systematic study of the structure of the sturgeon heart aimed at unraveling the relationship between the heart structure and the adaptive evolutionary changes. In a related paper, data were presented on the conus valves and the subendocardium. Here, the structure of the conus myocardium, the subepicardial tissue, and the conus-aorta transition were studied by conventional light, transmission, and scanning electron microscopy. In addition, actin localization by fluorescent phalloidin was used. The conus myocardium is organized into bundles whose spatial organization changes along the conus length. The variable orientation of the myocardial cell bundles may be effective in emptying the conus lumen during contraction and in preventing reflux of blood. Myocardial cell bundles are separated by loose connective tissue that contains collagen and elastin fibers, vessels, and extremely flat cells separating the cell bundles and enclosing blood vessels and collagen fibers. The ultrastructure of the myocardial cells was found to be very similar to that of other fish groups, suggesting that it is largely conservative. The subepicardium is characterized by the presence of nodular structures that contain lympho-hemopoietic (thymus-like) tissue in the young sturgeons and a large number of lymphocytes after the sturgeons reach sexual maturity. This tissue is likely implicated in the establishment and maintenance of the immune responses. The intrapericardial ventral aorta shows a middle layer of circumferentially oriented cells and internal and external layers with cells oriented longitudinally. Elastin fibers completely surround each smooth muscle cell, and the spaces between the different layers are occupied by randomly arranged collagen bundles. The intrapericardial segment of the ventral aorta is a true transitional segment whose structural characteristics are different from those of both the conus subendocardium and the rest of the ventral aorta. Copyright 2002 Wiley-Liss, Inc.

Tin-oxide-coated single-walled carbon nanotube bundles supporting platinum electrocatalysts for direct ethanol fuel cells.

PubMed

Hsu, Ryan S; Higgins, Drew; Chen, Zhongwei

2010-04-23

Novel tin-oxide (SnO(2))-coated single-walled carbon nanotube (SWNT) bundles supporting platinum (Pt) electrocatalysts for ethanol oxidation were developed for direct ethanol fuel cells. SnO(2)-coated SWNT (SnO(2)-SWNT) bundles were synthesized by a simple chemical-solution route. SnO(2)-SWNT bundles supporting Pt (Pt/SnO(2)-SWNTs) electrocatalysts and SWNT-supported Pt (Pt/SWNT) electrocatalysts were prepared by an ethylene glycol reduction method. The catalysts were physically characterized using TGA, XRD and TEM and electrochemically evaluated through cyclic voltammetry experiments. The Pt/SnO(2)-SWNTs showed greatly enhanced electrocatalytic activity for ethanol oxidation in acid medium, compared to the Pt/SWNT. The optimal SnO(2) loading of Pt/SnO(2)-SWNT catalysts with respect to specific catalytic activity for ethanol oxidation was also investigated.

From Biological Cilia to Artificial Flow Sensors: Biomimetic Soft Polymer Nanosensors with High Sensing Performance

PubMed Central

Asadnia, Mohsen; Kottapalli, Ajay Giri Prakash; Karavitaki, K. Domenica; Warkiani, Majid Ebrahimi; Miao, Jianmin; Corey, David P.; Triantafyllou, Michael

2016-01-01

We report the development of a new class of miniature all-polymer flow sensors that closely mimic the intricate morphology of the mechanosensory ciliary bundles in biological hair cells. An artificial ciliary bundle is achieved by fabricating bundled polydimethylsiloxane (PDMS) micro-pillars with graded heights and electrospinning polyvinylidenefluoride (PVDF) piezoelectric nanofiber tip links. The piezoelectric nature of a single nanofiber tip link is confirmed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Rheology and nanoindentation experiments are used to ensure that the viscous properties of the hyaluronic acid (HA)-based hydrogel are close to the biological cupula. A dome-shaped HA hydrogel cupula that encapsulates the artificial hair cell bundle is formed through precision drop-casting and swelling processes. Fluid drag force actuates the hydrogel cupula and deflects the micro-pillar bundle, stretching the nanofibers and generating electric charges. Functioning with principles analogous to the hair bundles, the sensors achieve a sensitivity and threshold detection limit of 300 mV/(m/s) and 8 μm/s, respectively. These self-powered, sensitive, flexible, biocompatibale and miniaturized sensors can find extensive applications in navigation and maneuvering of underwater robots, artificial hearing systems, biomedical and microfluidic devices. PMID:27622466

Herbicidal Spectrum, Absorption and Transportation, and Physiological Effect on Bidens pilosa of the Natural Alkaloid Berberine.

PubMed

Wu, Jiao; Ma, Jing-Jing; Liu, Bo; Huang, Lun; Sang, Xiao-Qing; Zhou, Li-Juan

2017-08-02

Berberine is a natural herbicidal alkaloid from Coptis chinensis Franch. Here we characterized its herbicidal spectrum and absorption and transportation in the plant, along with the possible mechanism. Berberine showed no effect on the germination of the 10 tested plants. The IC 50 values of berberine on the primary root length and fresh weight of the 10 tested plants ranged from 2.91 to 9.79 mg L -1 and 5.76 to 35.07 mg L -1 , respectively. Berberine showed a similar herbicidal effect on Bidens pilosa as the commercial naturally derived herbicide cinmethylin. HPLC and fluorescence analysis revealed that berberine was mainly absorbed by B. pilosa root and transported through vascular bundle acropetally. Enzyme activity studies, GC-MS analysis, and SEM and TEM observations indicated that berberine might first function on the cell membrane indicated by variation of the IUFA percent and then cause POD, PPO, and SOD activity changes and cellular structure deformity, which was eventually expressed as the decrease of cell adaptation ability and abnormal cell function and may even result in cell death. Environmental safety evaluation tests revealed that berberine was low in toxicity to Brachydanio rerio. These indicate that berberine has the potential to be a bioherbicide and/or a lead molecule for new herbicides.

Rasip1 regulates vertebrate vascular endothelial junction stability through Epac1-Rap1 signaling

PubMed Central

Wilson, Christopher W.; Parker, Leon H.; Hall, Christopher J.; Smyczek, Tanya; Mak, Judy; Crow, Ailey; Posthuma, George; De Mazière, Ann; Sagolla, Meredith; Chalouni, Cecile; Vitorino, Philip; Roose-Girma, Merone; Warming, Søren; Klumperman, Judith; Crosier, Philip S.

2013-01-01

Establishment and stabilization of endothelial tubes with patent lumens is vital during vertebrate development. Ras-interacting protein 1 (RASIP1) has been described as an essential regulator of de novo lumenogenesis through modulation of endothelial cell (EC) adhesion to the extracellular matrix (ECM). Here, we show that in mouse and zebrafish embryos, Rasip1-deficient vessels transition from an angioblast cord to a hollow tube, permit circulation of primitive erythrocytes, but ultimately collapse, leading to hemorrhage and embryonic lethality. Knockdown of RASIP1 does not alter EC-ECM adhesion, but causes cell-cell detachment and increases permeability of EC monolayers in vitro. We also found that endogenous RASIP1 in ECs binds Ras-related protein 1 (RAP1), but not Ras homolog gene family member A or cell division control protein 42 homolog. Using an exchange protein directly activated by cyclic adenosine monophosphate 1 (EPAC1)-RAP1–dependent model of nascent junction formation, we demonstrate that a fraction of the RASIP1 protein pool localizes to cell-cell contacts. Loss of RASIP1 phenocopies loss of RAP1 or EPAC1 in ECs by altering junctional actin organization, localization of the actin-bundling protein nonmuscle myosin heavy chain IIB, and junction remodeling. Our data show that RASIP1 regulates the integrity of newly formed blood vessels as an effector of EPAC1-RAP1 signaling. PMID:23886837

Invited Lectures from a Spatial Orientation Symposium in Honor of Frederick Guedry, Day 1

DTIC Science & Technology

2014-01-01

111  Computational Fluid Dynamics Model of Endolymph Flow around Hair Cell Bundle ̶ Wallace Grant...Wallace Grant: Computational Fluid Dynamics Model of Endolymph Flow around Hair Cell Bundle  Ian Curthoys: Update from Sydney  Discussion Tactile...usefulness of preserving free- flowing scholarly discussion. It is in the spirit of those fascinating early discussions among vestibular researchers1

The role of a Sertoli cell actin-myosin system in sperm bundle formation in the ratfish, Hydrolagus colliei (Chondrichthyes, Holocephali).

PubMed

Stanley, H P; Lambert, C C

1985-11-01

Sertoli cells in the ratfish entirely surround a clone of spermatids to form a spermatocyst. As spermiogenesis proceeds within the cyst cavity, the acrosome areas become apposed to the Sertoli cell plasma membrane lining the spermatocyst. The spermatids elongate and are gathered into an increasingly compact bundle oriented with acrosomal tips directed toward the Sertoli cell base. As all acrosome areas move closer together, Sertoli cell microfilaments oriented parallel to the long spermatid axis appear and increase in concentration. Actin and myosin were demonstrated in the microfilament area with fluorescent antibodies and NBD-Phallacidin. Simultaneously, endocytosis of Sertoli cell membrane between spermatid attachment sites removes the intervening membrane and allows the latter sites to approach each other. Sertoli cell endocytosis is spatially and temporally related to a unique projection at the basal rim of each acrosome. During midspermiogenesis, structured intercellular material appears between the Sertoli cell and the acrosomal region of each spermatid. Its periodicity is closely related to periodic arrangement of Sertoli cell actin and material within the spermatids. These attachment sites move together upon endocytosis, gathering a clone of spermatids into a closely packed bundle.

Size effects of single-walled carbon nanotubes on in vivo and in vitro pulmonary toxicity

PubMed Central

Fujita, Katsuhide; Fukuda, Makiko; Endoh, Shigehisa; Maru, Junko; Kato, Haruhisa; Nakamura, Ayako; Shinohara, Naohide; Uchino, Kanako; Honda, Kazumasa

2015-01-01

Abstract To elucidate the effect of size on the pulmonary toxicity of single-wall carbon nanotubes (SWCNTs), we prepared two types of dispersed SWCNTs, namely relatively thin bundles with short linear shapes (CNT-1) and thick bundles with long linear shapes (CNT-2), and conducted rat intratracheal instillation tests and in vitro cell-based assays using NR8383 rat alveolar macrophages. Total protein levels, MIP-1α expression, cell counts in BALF, and histopathological examinations revealed that CNT-1 caused pulmonary inflammation and slower recovery and that CNT-2 elicited acute lung inflammation shortly after their instillation. Comprehensive gene expression analysis confirmed that CNT-1-induced genes were strongly associated with inflammatory responses, cell proliferation, and immune system processes at 7 or 30 d post-instillation. Numerous genes were significantly upregulated or downregulated by CNT-2 at 1 d post-instillation. In vitro assays demonstrated that CNT-1 and CNT-2 SWCNTs were phagocytized by NR8383 cells. CNT-2 treatment induced cell growth inhibition, reactive oxygen species production, MIP-1α expression, and several genes involved in response to stimulus, whereas CNT-1 treatment did not exert a significant impact in these regards. These results suggest that SWCNTs formed as relatively thin bundles with short linear shapes elicited delayed pulmonary inflammation with slower recovery. In contrast, SWCNTs with a relatively thick bundle and long linear shapes sensitively induced cellular responses in alveolar macrophages and elicited acute lung inflammation shortly after inhalation. We conclude that the pulmonary toxicity of SWCNTs is closely associated with the size of the bundles. These physical parameters are useful for risk assessment and management of SWCNTs. PMID:25865113

ELMOD1 Stimulates ARF6-GTP Hydrolysis to Stabilize Apical Structures in Developing Vestibular Hair Cells.

PubMed

Krey, Jocelyn F; Dumont, Rachel A; Wilmarth, Philip A; David, Larry L; Johnson, Kenneth R; Barr-Gillespie, Peter G

2018-01-24

Sensory hair cells require control of physical properties of their apical plasma membranes for normal development and function. Members of the ADP-ribosylation factor (ARF) small GTPase family regulate membrane trafficking and cytoskeletal assembly in many cells. We identified ELMO domain-containing protein 1 (ELMOD1), a guanine nucleoside triphosphatase activating protein (GAP) for ARF6, as the most highly enriched ARF regulator in hair cells. To characterize ELMOD1 control of trafficking, we analyzed mice of both sexes from a strain lacking functional ELMOD1 [roundabout ( rda )]. In rda/rda mice, cuticular plates of utricle hair cells initially formed normally, then degenerated after postnatal day 5; large numbers of vesicles invaded the compromised cuticular plate. Hair bundles initially developed normally, but the cell's apical membrane lifted away from the cuticular plate, and stereocilia elongated and fused. Membrane trafficking in type I hair cells, measured by FM1-43 dye labeling, was altered in rda/rda mice. Consistent with the proposed GAP role for ELMOD1, the ARF6 GTP/GDP ratio was significantly elevated in rda/rda utricles compared with controls, and the level of ARF6-GTP was correlated with the severity of the rda/rda phenotype. These results suggest that conversion of ARF6 to its GDP-bound form is necessary for final stabilization of the hair bundle. SIGNIFICANCE STATEMENT Assembly of the mechanically sensitive hair bundle of sensory hair cells requires growth and reorganization of apical actin and membrane structures. Hair bundles and apical membranes in mice with mutations in the Elmod1 gene degenerate after formation, suggesting that the ELMOD1 protein stabilizes these structures. We show that ELMOD1 is a GTPase-activating protein in hair cells for the small GTP-binding protein ARF6, known to participate in actin assembly and membrane trafficking. We propose that conversion of ARF6 into the GDP-bound form in the apical domain of hair cells is essential for stabilizing apical actin structures like the hair bundle and ensuring that the apical membrane forms appropriately around the stereocilia. Copyright © 2018 the authors 0270-6474/18/380843-15$15.00/0.

Structured Post-IQ Domain Governs Selectivity of Myosin X for Fascin-Actin Bundles*

PubMed Central

Nagy, Stanislav; Rock, Ronald S.

2010-01-01

Without guidance cues, cytoskeletal motors would traffic components to the wrong destination with disastrous consequences for the cell. Recently, we identified a motor protein, myosin X, that identifies bundled actin filaments for transport. These bundles direct myosin X to a unique destination, the tips of cellular filopodia. Because the structural and kinetic features that drive bundle selection are unknown, we employed a domain-swapping approach with the nonselective myosin V to identify the selectivity module of myosin X. We found a surprising role of the myosin X tail region (post-IQ) in supporting long runs on bundles. Moreover, the myosin X head is adapted for initiating processive runs on bundles. We found that the tail is structured and biases the orientation of the two myosin X heads because a targeted insertion that introduces flexibility in the tail abolishes selectivity. Together, these results suggest how myosin motors may manage to read cellular addresses. PMID:20538587

The Triticum aestivum non-specific lipid transfer protein (TaLtp) gene family: comparative promoter activity of six TaLtp genes in transgenic rice.

PubMed

Boutrot, Freddy; Meynard, Donaldo; Guiderdoni, Emmanuel; Joudrier, Philippe; Gautier, Marie-Françoise

2007-03-01

Plant non-specific lipid transfer proteins (nsLTPs) are encoded by a multigene family and support physiological functions, which remain unclear. We adapted an efficient ligation-mediated polymerase chain reaction (LM-PCR) procedure that enabled isolation of 22 novel Triticum aestivum nsLtp (TaLtp) genes encoding types 1 and 2 nsLTPs. A phylogenetic tree clustered the wheat nsLTPs into ten subfamilies comprising 1-7 members. We also studied the activity of four type 1 and two type 2 TaLtp gene promoters in transgenic rice using the 1-Glucuronidase reporter gene. The activities of the six promoters displayed both overlapping and distinct features in rice. In vegetative organs, these promoters were active in leaves and root vascular tissues while no beta-Glucuronidase (GUS) activity was detected in stems. In flowers, the GUS activity driven by the TaLtp7.2a, TaLtp9.1a, TaLtp9.2d, and TaLtp9.3e gene promoters was associated with vascular tissues in glumes and in the extremities of anther filaments whereas only the TaLtp9.4a gene promoter was active in anther epidermal cells. In developing grains, GUS activity and GUS immunolocalization data evidenced complex patterns of activity of the TaLtp7.1a, TaLtp9.2d, and TaLtp9.4a gene promoters in embryo scutellum and in the grain epicarp cell layer. In contrast, GUS activity driven by TaLtp7.2a, TaLtp9.1a, and TaLtp9.3e promoters was restricted to the vascular bundle of the embryo scutellum. This diversity of TaLtp gene promoter activity supports the hypothesis that the encoded TaLTPs possess distinct functions in planta.

Fuel cell integral bundle assembly including ceramic open end seal and vertical and horizontal thermal expansion control

DOEpatents

Zafred, Paolo R [Murrysville, PA; Gillett, James E [Greensburg, PA

2012-04-24

A plurality of integral bundle assemblies contain a top portion with an inlet fuel plenum and a bottom portion containing a base support, the base supports a dense, ceramic air exhaust manifold having four supporting legs, the manifold is below and connects to air feed tubes located in a recuperator zone, the air feed tubes passing into the center of inverted, tubular, elongated, hollow electrically connected solid oxide fuel cells having an open end above a combustion zone into which the air feed tubes pass and a closed end near the inlet fuel plenum, where the open end of the fuel cells rest upon and within a separate combination ceramic seal and bundle support contained in a ceramic support casting, where at least one flexible cushion ceramic band seal located between the recuperator and fuel cells protects and controls horizontal thermal expansion, and where the fuel cells operate in the fuel cell mode and where the base support and bottom ceramic air exhaust manifolds carry from 85% to all of the weight of the generator.

Kidney of giraffes.

PubMed

Maluf, Noble Suydam Rustem

2002-06-01

This study focuses on certain aspects of the renal structure of the giraffe, with some implications as to its function. About 4,000 collecting ducts open at the truncated end of a curved crest that juts into the renal pelvis as the inner medulla (IM). Extensions of the pelvis pass between the medullary (MP) and vascular (VP) processes almost to the corticomedullary border. The MPs contain an IM and an outer medulla (OM) containing clusters of capillaries (vascular bundles). The VPs contain the interlobar arteries and veins. All of the IM and almost all of the OM, with its vascular bundles, are bathed with pelvic urine. The cortex comprises 63% of the parenchyma. The OM has nine times the mass of the IM. The IM comprises 4% of the parenchyma. The ratio of mass of the adult cortex to the medulla is 1.7:1.0, and the number of glomeruli per kidney is 6.6 x 10(6). Glomerular mass is 6.2-6.7% of renal mass in the adult and 5.2% in the 6-month-old calf. The dimensions of the glomerular capsules are the same across the thickness of the cortex. Every terminal collecting duct drains an estimated 1,650 nephrons. In the adult giraffe the ratio of thickness of the muscularis of the main renal artery (RA) to its diameter is 0.117 (right RA) and 0.132 (left RA). These ratios are close to those in rhinoceros and ox but greater than in man. The visceral arteries (celiac, anterior mesenteric, and renal) have about the same muscularis : diameter ratio. Giraffes have arterial hypertension, but atherosclerosis is apparently absent and serum lipid fractions are low. Copyright 2002 Wiley-Liss, Inc.

PCR localization of C-type natriuretic peptide and B-type receptor mRNAs in rat nephron segments.

PubMed

Terada, Y; Tomita, K; Nonoguchi, H; Yang, T; Marumo, F

1994-08-01

The present study was undertaken to investigate the presence of C-type natriuretic peptide (CNP) mRNA and its receptor, natriuretic peptide B-type receptor (ANPR-B) mRNA, in rat renal structures. The microlocalization of mRNAs coding for CNP and ANPR-B was carried out in the rat kidney, using an assay of reverse transcription and polymerase chain reaction (RT-PCR) in individual microdissected renal tubule segments, glomeruli, vasa recta bundle, and arcuate arteries. The PCR signal for CNP was detected in glomerulus, vasa recta bundle, and arcuate artery. The PCR product of ANPR-B was widely present in renal structures. Relatively large amounts of ANPR-B PCR product were detected in glomerulus, vasa recta bundle, arcuate artery, and distal nephron segments. A relatively high concentration of CNP (10(-7) M) stimulated guanosine 3',5'-cyclic monophosphate accumulation in glomerulus, medullary thick ascending limb, cortical collecting duct, and inner medullary collecting duct. Our data demonstrate that CNP can be produced locally in the glomerulus and renal vascular system and that ANPR-B is widely distributed in renal structures. Thus CNP may influence renal function and act in autocrine and paracrine fashions in the kidney.

The spatial expression and regulation of transcription factors IDEF1 and IDEF2

PubMed Central

Kobayashi, Takanori; Ogo, Yuko; Aung, May Sann; Nozoye, Tomoko; Itai, Reiko Nakanishi; Nakanishi, Hiromi; Yamakawa, Takashi; Nishizawa, Naoko K.

2010-01-01

Background and Aims Under conditions of low iron availability, rice plants induce genes involved in iron uptake and utilization. The iron deficiency-responsive cis-acting element binding factors 1 and 2 (IDEF1 and IDEF2) regulate transcriptional response to iron deficiency in rice roots. Clarification of the functions of IDEF1 and IDEF2 could uncover the gene regulation mechanism. Methods Spatial patterns of IDEF1 and IDEF2 expression were analysed by histochemical staining of IDEF1 and IDEF2 promoter-GUS transgenic rice lines. Expression patterns of the target genes of IDEF1 and IDEF2 were analysed using transformants with induced or repressed expression of IDEF1 or IDEF2 grown in iron-rich or in iron-deficient solutions for 1 d. Key Results IDEF1 and IDEF2 were highly expressed in the basal parts of the lateral roots and vascular bundles. IDEF1 and IDEF2 expression was dominant in leaf mesophyll and vascular cells, respectively. These expression patterns were similar under both iron-deficient and iron-sufficient conditions. IDEF1 was strongly expressed in pollen, ovaries, the aleurone layer and embryo. IDEF2 was expressed in pollen, ovaries and the dorsal vascular region of the endosperm. During seed germination, IDEF1 and IDEF2 were expressed in the endosperm and embryo. Expression of IDEF1 target genes was regulated in iron-rich roots similar to early iron-deficiency stages. In addition, the expression patterns of IDEF2 target genes were similar between iron-rich conditions and early or subsequent iron deficiency. Conclusions IDEF1 and IDEF2 are constitutively expressed during both vegetative and reproductive stages. The spatial expression patterns of IDEF1 and IDEF2 overlap with their target genes in restricted cell types, but not in all cells. The spatial expression patterns and gene regulation of IDEF1 and IDEF2 in roots are generally conserved under conditions of iron sufficiency and deficiency, suggesting complicated interactions with unknown factors for sensing and transmitting iron-deficiency signals. PMID:20197292

Metaproteomic identification of diazotrophic methanotrophs and their localization in root tissues of field-grown rice plants.

PubMed

Bao, Zhihua; Okubo, Takashi; Kubota, Kengo; Kasahara, Yasuhiro; Tsurumaru, Hirohito; Anda, Mizue; Ikeda, Seishi; Minamisawa, Kiwamu

2014-08-01

In a previous study by our group, CH4 oxidation and N2 fixation were simultaneously activated in the roots of wild-type rice plants in a paddy field with no N input; both processes are likely controlled by a rice gene for microbial symbiosis. The present study examined which microorganisms in rice roots were responsible for CH4 oxidation and N2 fixation under the field conditions. Metaproteomic analysis of root-associated bacteria from field-grown rice (Oryza sativa Nipponbare) revealed that nitrogenase complex-containing nitrogenase reductase (NifH) and the alpha subunit (NifD) and beta subunit (NifK) of dinitrogenase were mainly derived from type II methanotrophic bacteria of the family Methylocystaceae, including Methylosinus spp. Minor nitrogenase proteins such as Methylocella, Bradyrhizobium, Rhodopseudomonas, and Anaeromyxobacter were also detected. Methane monooxygenase proteins (PmoCBA and MmoXYZCBG) were detected in the same bacterial group of the Methylocystaceae. Because these results indicated that Methylocystaceae members mediate both CH4 oxidation and N2 fixation, we examined their localization in rice tissues by using catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH). The methanotrophs were localized around the epidermal cells and vascular cylinder in the root tissues of the field-grown rice plants. Our metaproteomics and CARD-FISH results suggest that CH4 oxidation and N2 fixation are performed mainly by type II methanotrophs of the Methylocystaceae, including Methylosinus spp., inhabiting the vascular bundles and epidermal cells of rice roots. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Absence of bundle structure in the neocortex of the reeler mouse at the embryonic stage. Studies by scanning electron microscopic fractography.

PubMed

Mikoshiba, K; Nishimura, Y; Tsukada, Y

The reeler mutant mouse is characterized by a derangement of the cerebral cortical structure due to abnormalities during the migration step at the embryonic stage. We have analyzed both the control and reeler cerebral cortex by means of scanning electron microscopic fractography. In the control cerebral cortex, the bundle formation was composed of fine fibers on which the migrating neuroblasts were attached perpendicular to the pial surface, whereas no bundle formation was observed in the reeler; instead, there was a fine meshwork of fibers surrounding the neuroblasts. The possible role of bundle formation in the normal cerebral cortex and the correlation between the inability of cells to migrate and the absence of bundle formation in the reeler is discussed.

Study of Sugarcane Pieces as Yeast Supports for Ethanol Production from Sugarcane Juice and Molasses Using Newly Isolated Yeast from Toddy Sap

PubMed Central

Satyanarayana, Botcha; Balakrishnan, Kesavapillai; Raghava Rao, Tamanam; Seshagiri Rao, Gudapaty

2012-01-01

A repeated batch fermentation system was used to produce ethanol using Saccharomyces cerevisiae strain (NCIM 3640) immobilized on sugarcane (Saccharum officinarum L.) pieces. For comparison free cells were also used to produce ethanol by repeated batch fermentation. Scanning electron microscopy evidently showed that cell immobilization resulted in firm adsorption of the yeast cells within subsurface cavities, capillary flow through the vessels of the vascular bundle structure, and attachment of the yeast to the surface of the sugarcane pieces. Repeated batch fermentations using sugarcane supported biocatalyst were successfully carried out for at least ten times without any significant loss in ethanol production from sugarcane juice and molasses. The number of cells attached to the support increased during the fermentation process, and fewer yeast cells leaked into fermentation broth. Ethanol concentrations (about 72.65~76.28 g/L in an average value) and ethanol productivities (about 2.27~2.36 g/L/hr in an average value) were high and stable, and residual sugar concentrations were low in all fermentations (0.9~3.25 g/L) with conversions ranging from 98.03~99.43%, showing efficiency 91.57~95.43 and operational stability of biocatalyst for ethanol fermentation. The results of the work pertaining to the use of sugarcane as immobilized yeast support could be promising for industrial fermentations. PMID:22783132

Engineering biomimetic hair bundle sensors for underwater sensing applications

NASA Astrophysics Data System (ADS)

Kottapalli, Ajay Giri Prakash; Asadnia, Mohsen; Karavitaki, K. Domenica; Warkiani, Majid Ebrahimi; Miao, Jianmin; Corey, David P.; Triantafyllou, Michael

2018-05-01

We present the fabrication of an artificial MEMS hair bundle sensor designed to approximate the structural and functional principles of the flow-sensing bundles found in fish neuromast hair cells. The sensor consists of micro-pillars of graded height connected with piezoelectric nanofiber "tip-links" and encapsulated by a hydrogel cupula-like structure. Fluid drag force actuates the hydrogel cupula and deflects the micro-pillar bundle, stretching the nanofibers and generating electric charges. These biomimetic sensors achieve an ultrahigh sensitivity of 0.286 mV/(mm/s) and an extremely low threshold detection limit of 8.24 µm/s. A complete version of this paper has been published [1].

Tau mediates microtubule bundle architectures mimicking fascicles of microtubules found in the axon initial segment

DOE PAGES

Chung, Peter J.; Song, Chaeyeon; Deek, Joanna; ...

2016-07-25

Tau, an intrinsically disordered protein confined to neuronal axons, binds to and regulates microtubule dynamics. Although there have been observations of string-like microtubule fascicles in the axon initial segment (AIS) and hexagonal bundles in neurite-like processes in non-neuronal cells overexpressing Tau, cell-free reconstitutions have not replicated either geometry. Here we map out the energy landscape of Tau-mediated, GTP-dependent ‘active’ microtubule bundles at 37°C, as revealed by synchrotron SAXS and TEM. Widely spaced bundles (wall-to-wall distance D w–w≈25–41nm) with hexagonal and string-like symmetry are observed, the latter mimicking bundles found in the AIS. A second energy minimum (D w–w≈16–23nm) is revealedmore » under osmotic pressure. The wide spacing results from a balance between repulsive forces, due to Tau’s projection domain (PD), and a stabilizing sum of transient sub-k BT cationic/anionic charge–charge attractions mediated by weakly penetrating opposing PDs. In the end, we find that this landscape would be significantly affected by charge-altering modifications of Tau associated with neurodegeneration.« less

A specialized outer layer of the primary cell wall joins elongating cotton fibers into tissue-like bundles.

PubMed

Singh, Bir; Avci, Utku; Eichler Inwood, Sarah E; Grimson, Mark J; Landgraf, Jeff; Mohnen, Debra; Sørensen, Iben; Wilkerson, Curtis G; Willats, William G T; Haigler, Candace H

2009-06-01

Cotton (Gossypium hirsutum) provides the world's dominant renewable textile fiber, and cotton fiber is valued as a research model because of its extensive elongation and secondary wall thickening. Previously, it was assumed that fibers elongated as individual cells. In contrast, observation by cryo-field emission-scanning electron microscopy of cotton fibers developing in situ within the boll demonstrated that fibers elongate within tissue-like bundles. These bundles were entrained by twisting fiber tips and consolidated by adhesion of a cotton fiber middle lamella (CFML). The fiber bundles consolidated via the CFML ultimately formed a packet of fiber around each seed, which helps explain how thousands of cotton fibers achieve their great length within a confined space. The cell wall nature of the CFML was characterized using transmission electron microscopy, including polymer epitope labeling. Toward the end of elongation, up-regulation occurred in gene expression and enzyme activities related to cell wall hydrolysis, and targeted breakdown of the CFML restored fiber individuality. At the same time, losses occurred in certain cell wall polymer epitopes (as revealed by comprehensive microarray polymer profiling) and sugars within noncellulosic matrix components (as revealed by gas chromatography-mass spectrometry analysis of derivatized neutral and acidic glycosyl residues). Broadly, these data show that adhesion modulated by an outer layer of the primary wall can coordinate the extensive growth of a large group of cells and illustrate dynamic changes in primary wall structure and composition occurring during the differentiation of one cell type that spends only part of its life as a tissue.

The new vestibular stimuli: sound and vibration-anatomical, physiological and clinical evidence.

PubMed

Curthoys, Ian S

2017-04-01

The classical view of the otoliths-as flat plates of fairly uniform receptors activated by linear acceleration dragging on otoconia and so deflecting the receptor hair bundles-has been replaced by new anatomical and physiological evidence which shows that the maculae are much more complex. There is anatomical spatial differentiation across the macula in terms of receptor types, hair bundle heights, stiffness and attachment to the overlying otolithic membrane. This anatomical spatial differentiation corresponds to the neural spatial differentiation of response dynamics from the receptors and afferents from different regions of the otolithic maculae. Specifically, receptors in a specialized band of cells, the striola, are predominantly type I receptors, with short, stiff hair bundles and looser attachment to the overlying otoconial membrane than extrastriolar receptors. At the striola the hair bundles project into holes in the otolithic membrane, allowing for fluid displacement to deflect the hair bundles and activate the cell. This review shows the anatomical and physiological evidence supporting the hypothesis that fluid displacement, generated by sound or vibration, deflects the short stiff hair bundles of type I receptors at the striola, resulting in neural activation of the irregular afferents innervating them. So these afferents are activated by sound or vibration and show phase-locking to individual cycles of the sound or vibration stimulus up to frequencies above 2000 Hz, underpinning the use of sound and vibration for clinical tests of vestibular function.

Immunocytochemical and autoradiographic studies on the process of keratinization in avian epidermis suggests absence of keratohyalin.

PubMed

Alibardi, Lorenzo

2004-02-01

The process of keratinization in apteric avian epidermis and in scutate scales of some avian species has been studied by autoradiography for histidine and immunohistochemistry for keratins and other epidermal proteins. Acidic or basic alpha-keratins are present in basal, spinosus, and transitional layers, but are not seen in the corneous layer. Keratinization-specific alpha-keratins (AE2-positive) are observed in the corneous layer of apteric epidermis but not in that of scutate scales, which contain mainly beta-keratin. Alpha-keratin bundles accumulate along the plasma membrane of transitional cells of apteric epidermis. In contrast to the situation in scutate scales, in the transitional layer and in the lowermost part of the corneous layer of apteric epidermis, filaggrin-like, loricrin-like, and transglutaminase immunoreactivities are present. The lack of isopeptide bond immunoreactivity suggests that undetectable isopeptide bonds are present in avian keratinocytes. Using immunogold ultrastructural immunocytochemistry a low but localized loricrin-like and, less, filaggrin-like labeling is seen over round-oval granules or vesicles among keratin bundles of upper spinosus and transitional keratinocytes of apteric epidermis. Filaggrin-and loricrin-labeling are absent in alpha-keratin bundles localized along the plasma membrane and in the corneous layer, formerly considered keratohyalin. Using ultrastructural autoradiography for tritiated histidine, occasional trace grains are seen among these alpha-keratin bundles. A different mechanism of redistribution of matrix and corneous cell envelope proteins probably operates in avian keratinocytes as compared to that of mammals. Keratin bundles are compacted around the lipid-core of apteric epidermis keratinocytes, which do not form complex chemico/mechanical-resistant corneous cell envelopes as in mammalian keratinocytes. These observations suggest that low amounts of matrix proteins are present among keratin bundles of avian keratinocytes and that keratohyalin granules are absent. Copyright 2003 Wiley-Liss, Inc.

The mechanosensory structure of the hair cell requires clarin-1, a protein encoded by Usher syndrome III causative gene.

PubMed

Geng, Ruishuang; Melki, Sami; Chen, Daniel H-C; Tian, Guilian; Furness, David N; Oshima-Takago, Tomoko; Neef, Jakob; Moser, Tobias; Askew, Charles; Horwitz, Geoff; Holt, Jeffrey R; Imanishi, Yoshikazu; Alagramam, Kumar N

2012-07-11

Mutation in the clarin-1 gene (Clrn1) results in loss of hearing and vision in humans (Usher syndrome III), but the role of clarin-1 in the sensory hair cells is unknown. Clarin-1 is predicted to be a four transmembrane domain protein similar to members of the tetraspanin family. Mice carrying null mutation in the clarin-1 gene (Clrn1(-/-)) show loss of hair cell function and a possible defect in ribbon synapse. We investigated the role of clarin-1 using various in vitro and in vivo approaches. We show by immunohistochemistry and patch-clamp recordings of Ca(2+) currents and membrane capacitance from inner hair cells that clarin-1 is not essential for formation or function of ribbon synapse. However, reduced cochlear microphonic potentials, FM1-43 [N-(3-triethylammoniumpropyl)-4-(4-(dibutylamino)styryl) pyridinium dibromide] loading, and transduction currents pointed to diminished cochlear hair bundle function in Clrn1(-/-) mice. Electron microscopy of cochlear hair cells revealed loss of some tall stereocilia and gaps in the v-shaped bundle, although tip links and staircase arrangement of stereocilia were not primarily affected by Clrn1(-/-) mutation. Human clarin-1 protein expressed in transfected mouse cochlear hair cells localized to the bundle; however, the pathogenic variant p.N48K failed to localize to the bundle. The mouse model generated to study the in vivo consequence of p.N48K in clarin-1 (Clrn1(N48K)) supports our in vitro and Clrn1(-/-) mouse data and the conclusion that CLRN1 is an essential hair bundle protein. Furthermore, the ear phenotype in the Clrn1(N48K) mouse suggests that it is a valuable model for ear disease in CLRN1(N48K), the most prevalent Usher syndrome III mutation in North America.

The Fysics of Filopodia (or The Physics of Philopodia)

NASA Astrophysics Data System (ADS)

Schwarz, Jen; Gopinathan, Ajay; Lee, Kun-Chun; Liu, Andrea; Yang, Louise

2006-03-01

Cell motility is driven by the dynamic reorganization of the cellular cytoskeleton which is composed of actin. Monomeric actin assembles into filaments that grow, shrink, branch and bundle. Branching generates new filaments that form a mesh-like structure that protrudes outward allowing the cell to move somewhere. But how does it know where to move? It has been proposed that filopodia serve as scouts for the cell. Filopodia are bundles of actin filaments that extend out ahead of the rest of the cell to probe its upcoming environment. Recent in vitro experiments [Vignjevic et al., J. Ce ll Bio. 160, 951 (2003)] determine the minimal ingredients required for such a process. We model these experiments analytically and via Monte Carlo simulations to estimate the typical bundle size and length. We also estimate the size of the mesh-like structure from which the filopodia emerge and explain the observed nonmonotonicity of this size as a function of capping protein concentration, which inhibits filament growth.

Are perioperative bundles associated with reduced postoperative morbidity in women undergoing benign hysterectomy? Retrospective cohort analysis of 16,286 cases in Michigan.

PubMed

Harris, John A; Sammarco, Anne G; Swenson, Carolyn W; Uppal, Shitanshu; Kamdar, Neil; Campbell, Darrel; Evilsizer, Sarah; DeLancey, John O; Morgan, Daniel M

2017-05-01

Healthcare teams that frequently follow a bundle of evidence-based processes provide care with lower rates of morbidity. Few process bundles to improve surgical outcomes in hysterectomy have been identified. The purpose of this study was to investigate whether a bundle of 4 perioperative care processes is associated with fewer postoperative complications and readmissions for hysterectomies in the Michigan Surgical Quality Collaborative. A bundle of perioperative care process goals was developed retrospectively with 30-day peri- and postoperative outcome data from the Hysterectomy Initiative in Michigan Surgical Quality Collaborative. All benign hysterectomies that had been performed between January 2013 and January 2015 were included. Based on evidence of lower complication rates after benign hysterectomy, the following processes were considered to be the "bundle": use of guideline-appropriate preoperative antibiotics, a minimally invasive surgical approach, operative duration <120 minutes, and avoidance of intraoperative hemostatic agent use. Each process was considered present or absent, and the number of processes was summed for a bundle score that ranged from 0-4. Cases with a score of zero were excluded. Outcomes measured were rates of complications (any and major) and hospital readmissions, all within 30 days of surgery. Postoperative events that were considered a "major complication" included acute renal failure, cardiac arrest that required cardiopulmonary resuscitation, central line infection, cerebral vascular accident, death, deep vein thrombosis, intestinal obstruction, myocardial infarction, pelvic abscess, pulmonary embolism, rectovaginal fistula, sepsis, surgical site infection (deep and organ-space), unplanned intubation, ureteral obstruction, and ureterovaginal and vesicovaginal fistula. The outcome "any complication" included all those events already described in addition to blood transfusion within 72 hours of surgery, urinary tract infection, and superficial surgical site infection. Outcomes were adjusted for patient demographics, surgical factors, and hospital-level clustering effects. There were 16,286 benign hysterectomies available for analysis. Among all hysterectomies that were reviewed, 33.6% met criteria for all bundle processes; however, there was wide variation in the rate among the 56 hospitals in the study sample with 9.1% of cases at the lowest quartile and 60.4% at the highest quartile of hospitals that met criteria for all bundle processes. Overall, the rate of any complication was 6.8% and of any major complication was 2.3%. The rate of hospital readmissions was 3.6%. After adjustment for confounders, in cases in which all bundle criterion were met compared with cases in which all bundle criterion were not met, the rate of any complications increased from 4.3-7.8% (P<.001); major complications increased from 1.7-2.6% (P<.001), and readmissions increased from 2.6-4.1% (P<.001). After adjustment for confounders, hospitals with greater rates of meeting all 4 criteria were associated significantly with lower hospital-level rates of postoperative complications (P<.001) and readmissions (P<.001). This multiinstitutional evaluation reveals that reduced morbidity and readmission are associated with rates of bundle compliance. The proposed bundle is a surgical goal, which is not possible in every case, and there is significant variation in the proportion of cases meeting all 4 bundle processes in Michigan hospitals. Implementation of evidence-based process bundles at a healthcare system level are worthy of prospective study to determine whether improvements in patient outcomes are possible. Copyright © 2017 Elsevier Inc. All rights reserved.

Flagellar Hook Flexibility Is Essential for Bundle Formation in Swimming Escherichia coli Cells

PubMed Central

Brown, Mostyn T.; Steel, Bradley C.; Silvestrin, Claudio; Wilkinson, David A.; Delalez, Nicolas J.; Lumb, Craig N.; Obara, Boguslaw; Berry, Richard M.

2012-01-01

Swimming Escherichia coli cells are propelled by the rotary motion of their flagellar filaments. In the normal swimming pattern, filaments positioned randomly over the cell form a bundle at the posterior pole. It has long been assumed that the hook functions as a universal joint, transmitting rotation on the motor axis through up to ∼90° to the filament in the bundle. Structural models of the hook have revealed how its flexibility is expected to arise from dynamic changes in the distance between monomers in the helical lattice. In particular, each of the 11 protofilaments that comprise the hook is predicted to cycle between short and long forms, corresponding to the inside and outside of the curved hook, once each revolution of the motor when the hook is acting as a universal joint. To test this, we genetically modified the hook so that it could be stiffened by binding streptavidin to biotinylated monomers, impeding their motion relative to each other. We found that impeding the action of the universal joint resulted in atypical swimming behavior as a consequence of disrupted bundle formation, in agreement with the universal joint model. PMID:22522898

Myosin IIA/IIB restrict adhesive and protrusive signaling to generate front-back polarity in migrating cells.

PubMed

Vicente-Manzanares, Miguel; Newell-Litwa, Karen; Bachir, Alexia I; Whitmore, Leanna A; Horwitz, Alan Rick

2011-04-18

Migratory front-back polarity emerges from the cooperative effect of myosin IIA (MIIA) and IIB (MIIB) on adhesive signaling. We demonstrate here that, during polarization, MIIA and MIIB coordinately promote localized actomyosin bundling, which generates large, stable adhesions that do not signal to Rac and thereby form the cell rear. MIIA formed dynamic actomyosin proto-bundles that mark the cell rear during spreading; it also bound to actin filament bundles associated with initial adhesion maturation in protrusions. Subsequent incorporation of MIIB stabilized the adhesions and actomyosin filaments with which it associated and formed a stable, extended rear. These adhesions did not turn over and no longer signal to Rac. Microtubules fine-tuned the polarity by positioning the front opposite the MIIA/MIIB-specified rear. Decreased Rac signaling in the vicinity of the MIIA/MIIB-stabilized proto-bundles and adhesions was accompanied by the loss of Rac guanine nucleotide exchange factor (GEFs), like βPIX and DOCK180, and by inhibited phosphorylation of key residues on adhesion proteins that recruit and activate Rac GEFs. These observations lead to a model for front-back polarity through local GEF depletion.

Calbindin and parvalbumin are early markers of non-mitotically regenerating hair cells in the bullfrog vestibular otolith organs

NASA Technical Reports Server (NTRS)

Steyger, P. S.; Burton, M.; Hawkins, J. R.; Schuff, N. R.; Baird, R. A.

1997-01-01

Earlier studies have demonstrated hair cell regeneration in the absence of cell proliferation, and suggested that supporting cells could phenotypically convert into hair cells following hair cell loss. Because calcium-binding proteins are involved in gene up-regulation, cell growth, and cell differentiation, we wished to determine if these proteins were up-regulated in scar formations and regenerating hair cells following gentamicin treatment. Calbindin and parvalbumin immunolabeling was examined in control or gentamicin-treated (GT) bullfrog saccular and utricular explants cultured for 3 days in amphibian culture medium or amphibian culture medium supplemented with aphidicolin, a blocker of nuclear DNA replication in eukaryotic cells. In control cultures, calbindin and parvalbumin immunolabeled the hair bundles and, less intensely, the cell bodies of mature hair cells. In GT or mitotically-blocked GT (MBGT) cultures, calbindin and parvalbumin immunolabeling was also seen in the hair bundles, cuticular plates, and cell bodies of hair cells with immature hair bundles. Thus, these antigens were useful markers for both normal and regenerating hair cells. Supporting cell immunolabeling was not seen in control cultures nor in the majority of supporting cells in GT cultures. In MBGT cultures, calbindin and parvalbumin immunolabeling was up-regulated in the cytosol of single supporting cells participating in scar formations and in supporting cells with hair cell-like characteristics. These data provide further evidence that non-mitotic hair cell regeneration in cultures can be accomplished by the conversion of supporting cells into hair cells.

Directional selectivity of afferent neurons in zebrafish neuromasts is regulated by Emx2 in presynaptic hair cells

PubMed Central

Ji, Young Rae; Warrier, Sunita; Jiang, Tao

2018-01-01

The orientation of hair bundles on top of sensory hair cells (HCs) in neuromasts of the lateral line system allows fish to detect direction of water flow. Each neuromast shows hair bundles arranged in two opposing directions and each afferent neuron innervates only HCs of the same orientation. Previously, we showed that this opposition is established by expression of Emx2 in half of the HCs, where it mediates hair bundle reversal (Jiang et al., 2017). Here, we show that Emx2 also regulates neuronal selection: afferent neurons innervate either Emx2-positive or negative HCs. In emx2 knockout and gain-of-function neuromasts, all HCs are unidirectional and the innervation patterns and physiological responses of the afferent neurons are dependent on the presence or absence of Emx2. Our results indicate that Emx2 mediates the directional selectivity of neuromasts by two distinct processes: regulating hair bundle orientation in HCs and selecting afferent neuronal targets. PMID:29671737

Involvement of microtubules and 10-nm filaments in the movement and positioning of nuclei in syncytia

PubMed Central

1979-01-01

Previous studies (Holmes, K.V., and P.W. Choppin. J. Exp. Med. 124:501- 520; J. Cell Biol. 39:526-543) showed that infection of baby hamster kidney (BHK21-F) cells with the parainfluenza virus SV5 causes extensive cell fusion, that nuclei migrate in the syncytial cytoplasm and align in tightly-packed rows, and that microtubules are involved in nuclear movement and alignment. The role of microtubules, 10-nm filaments, and actin-containing microfilaments in this process has been investigated by immunofluorescence microscopy using specific antisera, time-lapse cinematography, and electron microscopy. During cell fusion, micro tubules and 10-nm filaments from many cells form large bundles which are localized between rows of nuclei. No organized bundles of actin fibers were detected in these areas, although actin fibers were observed in regions away from the aligned nuclei. Although colchicine disrupts microtubules and inhibits nuclear movement, cytochalasin B (CB; 20-50 microgram/ml) does not inhibit cell fusion or nuclear movement. However, CB alters the shape of the syncytium, resulting in long filamentous processes extending from a central region. When these processes from neighboring cells make contact, fusion occurs, and nuclei migrate through the channels which are formed. Electron and immunofluorescence microscopy reveal bundles of microtubules and 10-nm filaments in parallel arrays within these processes, but no bundles of microfilaments were detected. The effect of CB on the structural integrity of microfilaments at this high concentration (20 microgram/ml) was demonstrated by the disappearance of filaments interacting with heavy meromyosin. Cycloheximide (20 microgram/ml) inhibits protein synthesis but does not affect cell fusion, the formation of microtubules and 10-nm filament bundles, or nuclear migration and alignment; thus, continued protein synthesis is not required. The association of microtubules and 10-nm filaments with nuclear migration and alignment suggests that microtubules and 10-nm filaments are two components in a system which serves both cytoskeletal and force-generating functions in intracellular movement and position of nuclei. PMID:227913

Erect panicle2 encodes a novel protein that regulates panicle erectness in indica rice.

PubMed

Zhu, Keming; Tang, Ding; Yan, Changjie; Chi, Zhengchang; Yu, Hengxiu; Chen, Jianmin; Liang, Jiansheng; Gu, Minghong; Cheng, Zhukuan

2010-02-01

Rice (Oryza sativa L.) inflorescence (panicle) architecture is an important agronomic trait for rice breeding. A number of high-yielding japonica rice strains, characterized by an erect panicle (EP) of their architecture, have been released as commercial varieties in China. But no EP-type indica varieties are released so far. Here, we identified two allelic erect-panicle mutants in indica rice, erect panicle2-1 (ep2-1) and erect panicle2-2 (ep2-2), exhibiting the characteristic erect panicle phenotype. Both mutants were derived from spontaneous mutation. We cloned the EP2 gene by way of a map-based cloning strategy, and a transgenic complementation test rescued the phenotype of ep2-1. Anatomical investigations revealed that the ep2 mutants have more vascular bundles and a thicker stem than that of wild-type plants, explaining the panicle erectness phenotype in ep2 mutants. It was shown that EP2 was specifically expressed in the vascular bundles of internodes by GUS staining and RT-PCR. EP2 encodes a novel plant-specific protein, which localizes to the endoplasmic reticulum with unknown biochemical function. In addition, EP2 also regulates other panicle characteristics, such as panicle length and grain size, but grain number per panicle shows little change, indicating that the mutation of the ep2 gene could be applied in EP-type indica rice breeding.

Roles of silica and lignin in horsetail (Equisetum hyemale), with special reference to mechanical properties

NASA Astrophysics Data System (ADS)

Yamanaka, Shigeru; Sato, Kanna; Ito, Fuyu; Komatsubara, Satoshi; Ohata, Hiroshi; Yoshino, Katsumi

2012-02-01

This research deals with detailed analyses of silica and lignin distribution in horsetail with special reference to mechanical strength. Scanning electron images of a cross-section of an internode showed silica deposited densely only around the outer epidermis. Detailed histochemical analyses of lignin showed no lignin deposition in the silica-rich outer internodes of horsetail, while a characteristic lignin deposition was noticed in the vascular bundle in inner side of internodes. To analyze the structure of horsetail from a mechanical viewpoint, we calculated the response of a model structure of horsetail to a mechanical force applied perpendicularly to the long axis by a finite element method. We found that silica distributed in the outer epidermis may play the major structural role, with lignin's role being limited ensuring that the vascular bundle keep waterproof. These results were in contrast to more modern tall trees like gymnosperms, for which lignin provides mechanical strength. Lignin has the advantage of sticking to cellulose, hemicellulose, and other materials. Such properties make it possible for plants containing lignin to branch. Branching of tree stems aids in competing for light and other atmospheric resources. This type of branching was impossible for ancient horsetails, which relied on the physical properties of silica. From the evolutional view points, over millennia in trees with high lignin content, true branching, and many chlorophyll-containing leaves developed.

SymB and SymC, two membrane associated proteins, are required for Epichloë festucae hyphal cell-cell fusion and maintenance of a mutualistic interaction with Lolium perenne.

PubMed

Green, Kimberly A; Becker, Yvonne; Tanaka, Aiko; Takemoto, Daigo; Fitzsimons, Helen L; Seiler, Stephan; Lalucque, Hervé; Silar, Philippe; Scott, Barry

2017-02-01

Cell-cell fusion in fungi is required for colony formation, nutrient transfer and signal transduction. Disruption of genes required for hyphal fusion in Epichloë festucae, a mutualistic symbiont of Lolium grasses, severely disrupts the host interaction phenotype. They examined whether symB and symC, the E. festucae homologs of Podospora anserina self-signaling genes IDC2 and IDC3, are required for E. festucae hyphal fusion and host symbiosis. Deletion mutants of these genes were defective in hyphal cell fusion, formed intra-hyphal hyphae, and had enhanced conidiation. SymB-GFP and SymC-mRFP1 localize to plasma membrane, septa and points of hyphal cell fusion. Plants infected with ΔsymB and ΔsymC strains were severely stunted. Hyphae of the mutants colonized vascular bundles, were more abundant than wild type in the intercellular spaces and formed intra-hyphal hyphae. Although these phenotypes are identical to those previously observed for cell wall integrity MAP kinase mutants no difference was observed in the basal level of MpkA phosphorylation or its cellular localization in the mutant backgrounds. Both genes contain binding sites for the transcription factor ProA. Collectively these results show that SymB and SymC are key components of a conserved signaling network for E. festucae to maintain a mutualistic symbiotic interaction within L. perenne. © 2016 The Authors. Molecular Microbiology Published by John Wiley & Sons Ltd.

Stimulus dependent properties of mammalian cochlear hair cell mechanoelectrical transduction

NASA Astrophysics Data System (ADS)

Scharr, A. L.; Ricci, Anthony

2018-05-01

Cochlear hair cell stereocilia move semi-independently, shaping the force transfer to mechanoelectrical transduction (MET) channels, as indicated by the MET current response. Semi-independent movement of stereocilia was evoked by stimulating inner hair cell (IHC) bundles from acutely dissected rat cochlea with stiff probes ranging in size from 1 to 10 µm. MET current responses were recorded using whole-cell patch-clamp electrophysiology. Small probes directly displaced stereocilia they contacted, and recruited adjacent stereocilia depending on stimulus magnitude. We inferred that the recruitment of stereocilia resulted in less uniform and less synchronous movement. Step displacements using smaller probes resulted in smaller current responses (from 1 nA for large probes to 0.3 nA for small, p <.0001), slower rate of current activation, as measured from the linear portion (from 4 nA/ms to 1 nA/ms, p <.0001), slower time constants of adaptation, as measured from double exponential fits from peak to steady state current (fast component: from 0.6 to 1.2 ms, p =.004; slow component: from 8 ms to 12 ms, p =.001) and less complete adaptation (from 95% to 30%, p <.0001). These results indicate that the mechanical properties of less coherent bundles greatly affect force transfer to MET channels as indicated by the electrical response of the cell. Thus, outer hair cells (OHCs), with their bundles embedded in the tectorial membrane, may exhibit synchronous MET activation and therefore time-dependent adaptation where fast adaptation provides a high pass filter. Hair cells with free standing bundles, like inner hair cells (IHC), may exhibit more asynchronous MET activation and adaptation, in which case adaptation would not provide this additional filter.

Exploring the membrane fusion mechanism through force-induced disassembly of HIV-1 six-helix bundle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Kai; Beijing Key Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101; University of Chinese Academy of Sciences, Beijing 100049

Enveloped virus, such as HIV-1, employs membrane fusion mechanism to invade into host cell. HIV-1 gp41 ectodomain uses six-helix bundle configuration to accomplish this process. Using molecular dynamic simulations, we confirmed the stability of this six-helix bundle by showing high occupancy of hydrogen bonds and hydrophobic interactions. Key residues and interactions important for the bundle integration were characterized by force-induced unfolding simulations of six-helix bundle, exhibiting the collapse order of these groups of interactions. Moreover, our results in some way concerted with a previous theory that the formation of coiled-coil choose a route which involved cooperative interactions between the N-terminalmore » and C-terminal helix. -- Highlights: •Unfolding of HIV-1 gp41 six-helix bundle is studied by molecular dynamics simulations. •Specific interactions responsible for the stability of HIV-1 envelope post-fusion conformation were identified. •The gp41 six-helix bundle transition inducing membrane fusion might be a cooperative process of the three subunits.« less

The 2006 William Feinberg lecture: shifting the paradigm from stroke to global vascular risk estimation.

PubMed

Sacco, Ralph L

2007-06-01

By the year 2010, it is estimated that 18.1 million people worldwide will die annually because of cardiovascular diseases and stroke. "Global vascular risk" more broadly includes the multiple overlapping disease silos of stroke, myocardial infarction, peripheral arterial disease, and vascular death. Estimation of global vascular risk requires consideration of a variety of variables including demographics, environmental behaviors, and risk factors. Data from multiple studies suggest continuous linear relationships between the physiological vascular risk modulators of blood pressure, lipids, and blood glucose rather than treating these conditions as categorical risk factors. Constellations of risk factors may be more relevant than individual categorical components. Exciting work with novel risk factors may also have predictive value in estimates of global vascular risk. Advances in imaging have led to the measurement of subclinical conditions such as carotid intima-media thickness and subclinical brain conditions such as white matter hyperintensities and silent infarcts. These subclinical measurements may be intermediate stages in the transition from asymptomatic to symptomatic vascular events, appear to be associated with the fundamental vascular risk factors, and represent opportunities to more precisely quantitate disease progression. The expansion of studies in molecular epidemiology and detection of genetic markers underlying vascular risks also promises to extend our precision of global vascular risk estimation. Global vascular risk estimation will require quantitative methods that bundle these multi-dimensional data into more precise estimates of future risk. The power of genetic information coupled with data on demographics, risk-inducing behaviors, vascular risk modulators, biomarkers, and measures of subclinical conditions should provide the most realistic approximation of an individual's future global vascular risk. The ultimate public health benefit, however, will depend on not only identification of global vascular risk but also the realization that we can modify this risk and prove the prediction models wrong.

X-ray CT and histological imaging of xylem vessels organization in Mimosa pudica.

PubMed

Lee, Sang Joon; Song, Kahye; Kim, Hae Koo; Park, Joonghyuk

2013-11-01

Mimosa pudica has three distinct specialized organs, namely, pulvinus, secondary pulvinus, and pulvinule, which are respectively controlling the movements of petioles, leaflets, and pinna in response to external stimuli. Water flow is a key factor for such movements, but detailed studies on the organization of the vascular system for water transport in these organs have not been published yet. In this study, organizations of the xylem vessels and morphological features of the pulvinus, the secondary pulvinus, and the pulvinule were experimentally investigated by X-ray computed tomography and histological technique. Results showed that the xylem vessels were circularly distributed in the specialized motile organs and reorganized into distinct vascular bundles at the extremities. The number and the total cross-sectional area of the xylem vessels were increased inside the specialized motile organs. Morphological characteristics obtained in this study provided new insight to understand the functions of the vascular networks in the dynamic movements of M. pudica. Copyright © 2013 Wiley Periodicals, Inc.

A 3D Poly(ethylene glycol)-based Tumor Angiogenesis Model to Study the Influence of Vascular Cells on Lung Tumor Cell Behavior

PubMed Central

Roudsari, Laila C.; Jeffs, Sydney E.; Witt, Amber S.; Gill, Bartley J.; West, Jennifer L.

2016-01-01

Tumor angiogenesis is critical to tumor growth and metastasis, yet much is unknown about the role vascular cells play in the tumor microenvironment. In vitro models that mimic in vivo tumor neovascularization facilitate exploration of this role. Here we investigated lung adenocarcinoma cancer cells (344SQ) and endothelial and pericyte vascular cells encapsulated in cell-adhesive, proteolytically-degradable poly(ethylene) glycol-based hydrogels. 344SQ in hydrogels formed spheroids and secreted proangiogenic growth factors that significantly increased with exposure to transforming growth factor beta 1 (TGF-β1), a potent tumor progression-promoting factor. Vascular cells in hydrogels formed tubule networks with localized activated TGF-β1. To study cancer cell-vascular cell interactions, we engineered a 2-layer hydrogel with 344SQ and vascular cell layers. Large, invasive 344SQ clusters (area > 5,000 μm2, circularity < 0.25) developed at the interface between the layers, and were not evident further from the interface or in control hydrogels without vascular cells. A modified model with spatially restricted 344SQ and vascular cell layers confirmed that observed cluster morphological changes required close proximity to vascular cells. Additionally, TGF-β1 inhibition blocked endothelial cell-driven 344SQ migration. Our findings suggest vascular cells contribute to tumor progression and establish this culture system as a platform for studying tumor vascularization. PMID:27596933

A 3D Poly(ethylene glycol)-based Tumor Angiogenesis Model to Study the Influence of Vascular Cells on Lung Tumor Cell Behavior

NASA Astrophysics Data System (ADS)

Roudsari, Laila C.; Jeffs, Sydney E.; Witt, Amber S.; Gill, Bartley J.; West, Jennifer L.

2016-09-01

Tumor angiogenesis is critical to tumor growth and metastasis, yet much is unknown about the role vascular cells play in the tumor microenvironment. In vitro models that mimic in vivo tumor neovascularization facilitate exploration of this role. Here we investigated lung adenocarcinoma cancer cells (344SQ) and endothelial and pericyte vascular cells encapsulated in cell-adhesive, proteolytically-degradable poly(ethylene) glycol-based hydrogels. 344SQ in hydrogels formed spheroids and secreted proangiogenic growth factors that significantly increased with exposure to transforming growth factor beta 1 (TGF-β1), a potent tumor progression-promoting factor. Vascular cells in hydrogels formed tubule networks with localized activated TGF-β1. To study cancer cell-vascular cell interactions, we engineered a 2-layer hydrogel with 344SQ and vascular cell layers. Large, invasive 344SQ clusters (area > 5,000 μm2, circularity < 0.25) developed at the interface between the layers, and were not evident further from the interface or in control hydrogels without vascular cells. A modified model with spatially restricted 344SQ and vascular cell layers confirmed that observed cluster morphological changes required close proximity to vascular cells. Additionally, TGF-β1 inhibition blocked endothelial cell-driven 344SQ migration. Our findings suggest vascular cells contribute to tumor progression and establish this culture system as a platform for studying tumor vascularization.

The evolution of plant secretory structures and emergence of terpenoid chemical diversity.

PubMed

Lange, Bernd Markus

2015-01-01

Secretory structures in terrestrial plants appear to have first emerged as intracellular oil bodies in liverworts. In vascular plants, internal secretory structures, such as resin ducts and laticifers, are usually found in conjunction with vascular bundles, whereas subepidermal secretory cavities and epidermal glandular trichomes generally have more complex tissue distribution patterns. The primary function of plant secretory structures is related to defense responses, both constitutive and induced, against herbivores and pathogens. The ability to sequester secondary (or specialized) metabolites and defense proteins in secretory structures was a critical adaptation that shaped plant-herbivore and plant-pathogen interactions. Although this review places particular emphasis on describing the evolution of pathways leading to terpenoids, it also assesses the emergence of other metabolite classes to outline the metabolic capabilities of different plant lineages.

Speckle-correlation monitoring of the internal micro-vascular flow

NASA Astrophysics Data System (ADS)

Zimnyakov, D. A.; Khmara, M. B.; Vilensky, M. A.; Kozlov, V. V.; Gorfinkel, I. V.; Zdrajevsky, R. A.

2009-10-01

The results of experimental study of possibility to monitor the micro-vascular blood flow in superficial tissues of various organs with the use of endoscope-based full-field speckle correlometer are presented. The blood microcirculation monitoring was carried out in the course of the laparotomy of abdominal cavity of laboratory animals (rats). Transfer of laser light to the area of interest and scattered radiation from the probed zone to the detector (CMOS camera) was carried out via fiber-optic bundles of endoscopic system. Microscopic hemodynamics was analyzed for small intestine, liver, spleen, kidney, and pancreas under different conditions (normal state, provocated peritonitis and ischemia, administration of vasodilative agents such as papaverine, lidocaine). The prospects and problems of internal monitoring of microvascular flow in laboratory and clinical conditions are discussed.

Scanning Electron Microscope Examination of Cotton Linters and Wood Pulp Fibers before and after Nitration and Gun Propellant Manufacture

DTIC Science & Technology

1983-03-01

both types of cellulose , the cell walls are still intact with the microfibrils showing little damage. The cellulose microfibrils consist of long chains...25 2. Model of Cellulose Microfibril ... S............. .............. .26 3. Model of Plant Cell Wall Bonding of Microfibril Bundles...molecules protrude above and below the plane of the cellulose ribbon.J’ (See Figures 2 and 3,) Bundles of these cellulose ribbons are called microfibrils

Rice Ovate Family Protein 2 (OFP2) alters hormonal homeostasis and vasculature development.

PubMed

Schmitz, Aaron J; Begcy, Kevin; Sarath, Gautam; Walia, Harkamal

2015-12-01

OFP (Ovate Family Protein) is a transcription factor family found only in plants. In dicots, OFPs control fruit shape and secondary cell wall biosynthesis. OFPs are also thought to function through interactions with KNOX and BELL transcription factors. Here, we have functionally characterized OsOFP2, a member of the OFP subgroup associated with regulating fruit shape. OsOFP2 was found to localize to the nucleus and to the cytosol. A putative nuclear export signal was identified within the OVATE domain and was required for the localization of OsOFP2 to distinct cytosolic spots. Rice plants overexpressing OsOFP2 were reduced in height and exhibited altered leaf morphology, seed shape, and positioning of vascular bundles in stems. Transcriptome analysis indicated disruptions of genes associated with vasculature development, lignin biosynthesis, and hormone homeostasis. Reduced expression of the gibberellin biosynthesis gene GA 20-oxidase 7 coincided with lower gibberellin content in OsOFP2 overexpression lines. Also, we found that OsOFP2 was expressed in plant vasculature and determined that putative vascular development KNOX and BELL proteins interact with OsOFP2. KNOX and BELL genes are known to suppress gibberellin biosynthesis through GA20ox gene regulation and can restrict lignin biosynthesis. We propose that OsOFP2 could modulate KNOX-BELL function to control diverse aspects of development including vasculature development. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

A natural variant of NAL1, selected in high-yield rice breeding programs, pleiotropically increases photosynthesis rate.

PubMed

Takai, Toshiyuki; Adachi, Shunsuke; Taguchi-Shiobara, Fumio; Sanoh-Arai, Yumiko; Iwasawa, Norio; Yoshinaga, Satoshi; Hirose, Sakiko; Taniguchi, Yojiro; Yamanouchi, Utako; Wu, Jianzhong; Matsumoto, Takashi; Sugimoto, Kazuhiko; Kondo, Katsuhiko; Ikka, Takashi; Ando, Tsuyu; Kono, Izumi; Ito, Sachie; Shomura, Ayahiko; Ookawa, Taiichiro; Hirasawa, Tadashi; Yano, Masahiro; Kondo, Motohiko; Yamamoto, Toshio

2013-01-01

Improvement of leaf photosynthesis is an important strategy for greater crop productivity. Here we show that the quantitative trait locus GPS (GREEN FOR PHOTOSYNTHESIS) in rice (Oryza sativa L.) controls photosynthesis rate by regulating carboxylation efficiency. Map-based cloning revealed that GPS is identical to NAL1 (NARROW LEAF1), a gene previously reported to control lateral leaf growth. The high-photosynthesis allele of GPS was found to be a partial loss-of-function allele of NAL1. This allele increased mesophyll cell number between vascular bundles, which led to thickened leaves, and it pleiotropically enhanced photosynthesis rate without the detrimental side effects observed in previously identified nal1 mutants, such as dwarf plant stature. Furthermore, pedigree analysis suggested that rice breeders have repeatedly selected the high-photosynthesis allele in high-yield breeding programs. The identification and utilization of NAL1 (GPS) can enhance future high-yield breeding and provides a new strategy for increasing rice productivity.

A natural variant of NAL1, selected in high-yield rice breeding programs, pleiotropically increases photosynthesis rate

PubMed Central

Takai, Toshiyuki; Adachi, Shunsuke; Taguchi-Shiobara, Fumio; Sanoh-Arai, Yumiko; Iwasawa, Norio; Yoshinaga, Satoshi; Hirose, Sakiko; Taniguchi, Yojiro; Yamanouchi, Utako; Wu, Jianzhong; Matsumoto, Takashi; Sugimoto, Kazuhiko; Kondo, Katsuhiko; Ikka, Takashi; Ando, Tsuyu; Kono, Izumi; Ito, Sachie; Shomura, Ayahiko; Ookawa, Taiichiro; Hirasawa, Tadashi; Yano, Masahiro; Kondo, Motohiko; Yamamoto, Toshio

2013-01-01

Improvement of leaf photosynthesis is an important strategy for greater crop productivity. Here we show that the quantitative trait locus GPS (GREEN FOR PHOTOSYNTHESIS) in rice (Oryza sativa L.) controls photosynthesis rate by regulating carboxylation efficiency. Map-based cloning revealed that GPS is identical to NAL1 (NARROW LEAF1), a gene previously reported to control lateral leaf growth. The high-photosynthesis allele of GPS was found to be a partial loss-of-function allele of NAL1. This allele increased mesophyll cell number between vascular bundles, which led to thickened leaves, and it pleiotropically enhanced photosynthesis rate without the detrimental side effects observed in previously identified nal1 mutants, such as dwarf plant stature. Furthermore, pedigree analysis suggested that rice breeders have repeatedly selected the high-photosynthesis allele in high-yield breeding programs. The identification and utilization of NAL1 (GPS) can enhance future high-yield breeding and provides a new strategy for increasing rice productivity. PMID:23985993

A secreted Ustilago maydis effector promotes virulence by targeting anthocyanin biosynthesis in maize

PubMed Central

Tanaka, Shigeyuki; Brefort, Thomas; Neidig, Nina; Djamei, Armin; Kahnt, Jörg; Vermerris, Wilfred; Koenig, Stefanie; Feussner, Kirstin; Feussner, Ivo; Kahmann, Regine

2014-01-01

The biotrophic fungus Ustilago maydis causes smut disease in maize with characteristic tumor formation and anthocyanin induction. Here, we show that anthocyanin biosynthesis is induced by the virulence promoting secreted effector protein Tin2. Tin2 protein functions inside plant cells where it interacts with maize protein kinase ZmTTK1. Tin2 masks a ubiquitin–proteasome degradation motif in ZmTTK1, thus stabilizing the active kinase. Active ZmTTK1 controls activation of genes in the anthocyanin biosynthesis pathway. Without Tin2, enhanced lignin biosynthesis is observed in infected tissue and vascular bundles show strong lignification. This is presumably limiting access of fungal hyphae to nutrients needed for massive proliferation. Consistent with this assertion, we observe that maize brown midrib mutants affected in lignin biosynthesis are hypersensitive to U. maydis infection. We speculate that Tin2 rewires metabolites into the anthocyanin pathway to lower their availability for other defense responses. DOI: http://dx.doi.org/10.7554/eLife.01355.001 PMID:24473076

Plant Flavonoids—Biosynthesis, Transport and Involvement in Stress Responses

PubMed Central

Petrussa, Elisa; Braidot, Enrico; Zancani, Marco; Peresson, Carlo; Bertolini, Alberto; Patui, Sonia; Vianello, Angelo

2013-01-01

This paper aims at analysing the synthesis of flavonoids, their import and export in plant cell compartments, as well as their involvement in the response to stress, with particular reference to grapevine (Vitis vinifera L.). A multidrug and toxic compound extrusion (MATE) as well as ABC transporters have been demonstrated in the tonoplast of grape berry, where they perform a flavonoid transport. The involvement of a glutathione S-transferase (GST) gene has also been inferred. Recently, a putative flavonoid carrier, similar to mammalian bilitranslocase (BTL), has been identified in both grape berry skin and pulp. In skin the pattern of BTL expression increases from véraison to harvest, while in the pulp its expression reaches the maximum at the early ripening stage. Moreover, the presence of BTL in vascular bundles suggests its participation in long distance transport of flavonoids. In addition, the presence of a vesicular trafficking in plants responsible for flavonoid transport is discussed. Finally, the involvement of flavonoids in the response to stress is described. PMID:23867610

Proangiogenic scaffolds as functional templates for cardiac tissue engineering.

PubMed

Madden, Lauran R; Mortisen, Derek J; Sussman, Eric M; Dupras, Sarah K; Fugate, James A; Cuy, Janet L; Hauch, Kip D; Laflamme, Michael A; Murry, Charles E; Ratner, Buddy D

2010-08-24

We demonstrate here a cardiac tissue-engineering strategy addressing multicellular organization, integration into host myocardium, and directional cues to reconstruct the functional architecture of heart muscle. Microtemplating is used to shape poly(2-hydroxyethyl methacrylate-co-methacrylic acid) hydrogel into a tissue-engineering scaffold with architectures driving heart tissue integration. The construct contains parallel channels to organize cardiomyocyte bundles, supported by micrometer-sized, spherical, interconnected pores that enhance angiogenesis while reducing scarring. Surface-modified scaffolds were seeded with human ES cell-derived cardiomyocytes and cultured in vitro. Cardiomyocytes survived and proliferated for 2 wk in scaffolds, reaching adult heart densities. Cardiac implantation of acellular scaffolds with pore diameters of 30-40 microm showed angiogenesis and reduced fibrotic response, coinciding with a shift in macrophage phenotype toward the M2 state. This work establishes a foundation for spatially controlled cardiac tissue engineering by providing discrete compartments for cardiomyocytes and stroma in a scaffold that enhances vascularization and integration while controlling the inflammatory response.

Proangiogenic scaffolds as functional templates for cardiac tissue engineering

PubMed Central

Madden, Lauran R.; Mortisen, Derek J.; Sussman, Eric M.; Dupras, Sarah K.; Fugate, James A.; Cuy, Janet L.; Hauch, Kip D.; Laflamme, Michael A.; Murry, Charles E.; Ratner, Buddy D.

2010-01-01

We demonstrate here a cardiac tissue-engineering strategy addressing multicellular organization, integration into host myocardium, and directional cues to reconstruct the functional architecture of heart muscle. Microtemplating is used to shape poly(2-hydroxyethyl methacrylate-co-methacrylic acid) hydrogel into a tissue-engineering scaffold with architectures driving heart tissue integration. The construct contains parallel channels to organize cardiomyocyte bundles, supported by micrometer-sized, spherical, interconnected pores that enhance angiogenesis while reducing scarring. Surface-modified scaffolds were seeded with human ES cell-derived cardiomyocytes and cultured in vitro. Cardiomyocytes survived and proliferated for 2 wk in scaffolds, reaching adult heart densities. Cardiac implantation of acellular scaffolds with pore diameters of 30–40 μm showed angiogenesis and reduced fibrotic response, coinciding with a shift in macrophage phenotype toward the M2 state. This work establishes a foundation for spatially controlled cardiac tissue engineering by providing discrete compartments for cardiomyocytes and stroma in a scaffold that enhances vascularization and integration while controlling the inflammatory response. PMID:20696917

Structure and immunocytochemical localization of photosynthetic enzymes in the lamina joint and sheath pulvinus of the C4 grass Arundinella hirta.

PubMed

Wakayama, Masataka; Ohnishi, Jun-ichi; Ueno, Osamu

2013-03-01

The C(4) grass Arundinella hirta exhibits a unique C(4) anatomy, with isolated Kranz cells (distinctive cells) and C(4)-type expression of photosynthetic enzymes in the leaf sheath and stem as well as in the leaf blade. The border zones between these organs are pale green. Those between the leaf blade and sheath and between the sheath and stem are called the lamina joint and sheath pulvinus, respectively, and are involved in gravity sensing. We investigated the structure and localization of C(3) and C(4) photosynthetic enzymes in these tissues. In both zones the epidermis lacked stomata. The inner tissue was composed of parenchyma cells and vascular bundles. The parenchyma cells were densely packed with small intercellular spaces and contained granal chloroplasts with large starch grains. No C(4)-type cellular differentiation was recognized. Western blot analysis showed that the lamina joint and pulvinus accumulated substantial amounts of phosphoenolpyruvate carboxylase (PEPC), pyruvate,Pi dikinase (PPDK), and ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco). Immunogold electron microscopy revealed PEPC in the cytosol and both PPDK and rubisco in the chloroplasts of parenchyma cells, suggesting the occurrence of C(3) and C(4) enzymes within a single type of chlorenchyma cell. These data indicate that the lamina joint and pulvinus have unique expression patterns of C(3) and C(4) enzymes, unlike those in C(4)-type anatomy.

The Mechanosensory Structure of the Hair Cell Requires Clarin-1, a Protein Encoded by Usher Syndrome III Causative Gene

PubMed Central

Geng, Ruishuang; Melki, Sami; Chen, Daniel H.-C.; Tian, Guilian; Furness, David; Oshima-Takago, Tomoko; Neef, Jakob; Moser, Tobias; Askew, Charles; Horwitz, Geoff; Holt, Jeffrey; Imanishi, Yoshikazu; Alagramam, Kumar N.

2012-01-01

Mutation in the clarin-1 gene results in loss of hearing and vision in humans (Usher syndrome III), but the role of clarin-1 in the sensory hair cells is unknown. Clarin-1 is predicted to be a four transmembrane domain protein similar to members of the tetraspanin family. Mice carrying null mutation in the clarin-1 (Clrn1−/−) gene show loss of hair cell function and a possible defect in ribbon synapse. We investigated the role of clarin-1 using various in vitro and in vivo approaches. We show by immunohistochemistry and patch-clamp recordings of Ca2+ currents and membrane capacitance from IHCs that clarin-1 is not essential for formation or function of ribbon synapse. However, reduced cochlear microphonic potentials, FM1-43 loading and transduction currents pointed to diminished cochlear hair bundle function in Clrn1−/− mice. Electron microscopy of cochlear hair cells revealed loss of some tall stereocilia and gaps in the v-shaped bundle, although tip-links and staircase arrangement of stereocilia were not primarily affected by Clrn1−/− mutation. Human clarin-1 protein expressed in transfected mouse cochlear hair cells localized to the bundle; however, the pathogenic variant, p.N48K, failed to localize to the bundle. The mouse model generated to study the in vivo consequence of p. N48K in clarin-1 (Clrn1N48K) supports our in vitro and Clrn1−/− mouse data and the conclusion that CLRN1 is an essential hair bundle protein. Further, the ear phenotype in the Clrn1N48K mouse suggests that it is a valuable model for ear disease in CLRN1N48K, the most prevalent Usher III mutation in North America. PMID:22787034

Functional Utrastructure of Genlisea (Lentibulariaceae) Digestive Hairs

PubMed Central

Płachno, Bartosz Jan; Kozieradzka-Kiszkurno, Małgorzata; Świątek, Piotr

2007-01-01

Background and Aims Digestive structures of carnivorous plants produce external digestive enzymes, and play the main role in absorption. In Lentibulariaceae, the ultrastructure of digestive hairs has been examined in some detail in Pinguicula and Utricularia, but the sessile digestive hairs of Genlisea have received very little attention so far. The aim of this study was to fill this gap by expanding their morphological, anatomical and histochemical characterization. Methods Several imaging techniques were used, including light, confocal and electron microscopy, to reveal the structure and function of the secretory hairs of Genlisea traps. This report demonstrates the application of cryo-SEM for fast imaging of whole, physically fixed plant secretory structures. Key Results and Conclusion The concentration of digestive hairs along vascular bundles in subgenus Genlisea is a primitive feature, indicating its basal position within the genus. Digestive hairs of Genlisea consist of three compartments with different ultrastructure and function. In subgenus Tayloria the terminal hair cells are transfer cells, but not in species of subgenus Genlisea. A digestive pool of viscous fluid occurs in Genlisea traps. In spite of their similar architecture, the digestive-absorptive hairs of Lentibulariaceae feature differences in morphology and ultrastructure. PMID:17550910

Mechanical properties of sensory hair bundles are reflected in their Brownian motion measured with a laser differential interferometer.

PubMed Central

Denk, W; Webb, W W; Hudspeth, A J

1989-01-01

By optically probing with a focused, low-power laser beam, we measured the spontaneous deflection fluctuations of the sensory hair bundles on frog saccular hair cells with a sensitivity of about 1 pm/square root of Hz. The preparation was illuminated by two orthogonally polarized laser beams separated by only about 0.2 microns at their foci in the structure under investigation. Slight movement of the object from one beam toward the other caused a change of the phase difference between the transmitted beams and an intensity modulation at the detector where the beams interfered. Maintenance of the health of the cells and function of the transduction mechanism were occasionally confirmed by measuring the intracellular resting potential and the sensitivity of transduction. The root-mean-square (rms) displacement of approximately 3.5 nm at a hair bundle's tip suggests a stiffness of about 350 microN/m, in agreement with measurements made with a probe attached to a bundle's tip. The spectra resemble those of overdamped harmonic oscillators with roll-off frequencies between 200 and 800 Hz. Because the roll-off frequencies depended strongly on the viscosity of the bathing medium, we conclude that hair-bundle motion is mainly damped by the surrounding fluid. PMID:2787510

Enhanced signal-to-noise ratios in frog hearing can be achieved through amplitude death

PubMed Central

Ahn, Kang-Hun

2013-01-01

In the ear, hair cells transform mechanical stimuli into neuronal signals with great sensitivity, relying on certain active processes. Individual hair cell bundles of non-mammals such as frogs and turtles are known to show spontaneous oscillation. However, hair bundles in vivo must be quiet in the absence of stimuli, otherwise the signal is drowned in intrinsic noise. Thus, a certain mechanism is required in order to suppress intrinsic noise. Here, through a model study of elastically coupled hair bundles of bullfrog sacculi, we show that a low stimulus threshold and a high signal-to-noise ratio (SNR) can be achieved through the amplitude death phenomenon (the cessation of spontaneous oscillations by coupling). This phenomenon occurs only when the coupled hair bundles have inhomogeneous distribution, which is likely to be the case in biological systems. We show that the SNR has non-monotonic dependence on the mass of the overlying membrane, and find out that the SNR has maximum value in the region of amplitude death. The low threshold of stimulus through amplitude death may account for the experimentally observed high sensitivity of frog sacculi in detecting vibration. The hair bundles' amplitude death mechanism provides a smart engineering design for low-noise amplification. PMID:23883956

Developmental Response of a Resistance-Breaking Population of Meloidogyne arenaria on Vitis spp.

PubMed

Anwar, Safdar A; McKenry, M V

2002-03-01

Pre- and post-infection resistance mechanisms expressed by Vitis rootstocks RS-9 and Teleki 5C against second-stage juveniles (J2) of resistance-breaking populations of Meloidogyne arenaria were observed and correlated with juvenile development and nematode reproduction. Cabernet Sauvignon grape was used as a susceptible control for comparison. Similar numbers of J2 penetrated Teleki 5C and Cabernet Sauvignon roots. Root-tip necrosis, a hypersensitive reaction, occurred in both rootstocks but was effective in reducing J2 penetration only in RS-9 roots. Juvenile development occurred in roots of all three rootstocks by 13 days after inoculation, with the highest number of swollen juveniles present in Cabernet Sauvignon roots. Cortical necroses restricted the ability of J2 to reach vascular bundles, thereby restricting access to successful feeding sites and leading to dead or underdeveloped juveniles in RS-9 roots. At 35 days after inoculation, only 5% and 25% of the initial inoculum in RS-9 and Teleki 5C roots, respectively, reached the adult stage compared to 32% in Cabernet roots. Giant cells were of sufficient size to support nematode development to maturity in Cabernet. Cell necrosis and underdeveloped giant cells were apparent in the resistant rootstocks, which delayed development of adults and limited egg production. Inadequate development of giant cells may provide long-term population reductions in woody-rooted perennial crops.

Characterization of a cinnamoyl-CoA reductase 1 (CCR1) mutant in maize: effects on lignification, fibre development, and global gene expression

PubMed Central

Tamasloukht, Barek; Wong Quai Lam, Mary Sarah-Jane; Martinez, Yves; Tozo, Koffi; Barbier, Odile; Jourda, Cyril; Jauneau, Alain; Borderies, Gisèle; Balzergue, Sandrine; Renou, Jean-Pierre; Huguet, Stéphanie; Martinant, Jean Pierre; Tatout, Christophe; Lapierre, Catherine; Barrière, Yves; Goffner, Deborah; Pichon, Magalie

2011-01-01

Cinnamoyl-CoA reductase (CCR), which catalyses the first committed step of the lignin-specific branch of monolignol biosynthesis, has been extensively characterized in dicot species, but few data are available in monocots. By screening a Mu insertional mutant collection in maize, a mutant in the CCR1 gene was isolated named Zmccr1–. In this mutant, CCR1 gene expression is reduced to 31% of the residual wild-type level. Zmccr1– exhibited enhanced digestibility without compromising plant growth and development. Lignin analysis revealed a slight decrease in lignin content and significant changes in lignin structure. p-Hydroxyphenyl units were strongly decreased and the syringyl/guaiacyl ratio was slightly increased. At the cellular level, alterations in lignin deposition were mainly observed in the walls of the sclerenchymatic fibre cells surrounding the vascular bundles. These cell walls showed little to no staining with phloroglucinol. These histochemical changes were accompanied by an increase in sclerenchyma surface area and an alteration in cell shape. In keeping with this cell type-specific phenotype, transcriptomics performed at an early stage of plant development revealed the down-regulation of genes specifically associated with fibre wall formation. To the present authors’ knowledge, this is the first functional characterization of CCR1 in a grass species. PMID:21493812

HMGB1 Promotes Intraoral Palatal Wound Healing through RAGE-Dependent Mechanisms.

PubMed

Tancharoen, Salunya; Gando, Satoshi; Binita, Shrestha; Nagasato, Tomoka; Kikuchi, Kiyoshi; Nawa, Yuko; Dararat, Pornpen; Yamamoto, Mika; Narkpinit, Somphong; Maruyama, Ikuro

2016-11-23

High mobility group box 1 (HMGB1) is tightly connected to the process of tissue organization upon tissue injury. Here we show that HMGB1 controls epithelium and connective tissue regeneration both in vivo and in vitro during palatal wound healing. Heterozygous HMGB1 ( Hmgb1 +/- ) mice and Wild-type (WT) mice were subjected to palatal injury. Maxillary tissues were stained with Mallory Azan or immunostained with anti-HMGB1, anti-proliferating cell nuclear antigen (PCNA), anti-nuclear factor-κB (NF-κB) p50 and anti-vascular endothelial growth factor (VEGF) antibodies. Palatal gingival explants were cultured with recombinant HMGB1 (rHMGB1) co-treated with siRNA targeting receptor for advanced glycation end products (RAGEs) for cell migration and PCNA expression analysis. Measurement of the wound area showed differences between Hmgb1 +/- and WT mice on Day 3 after wounding. Mallory Azan staining showed densely packed of collagen fibers in WT mice, whereas in Hmgb1 +/- mice weave-like pattern of low density collagen bundles were present. At three and seven days post-surgery, PCNA, NF-κB p50 and VEGF positive keratinocytes of WT mice were greater than that of Hmgb1 +/- mice. Knockdown of RAGE prevents the effect of rHMGB1-induced cell migration and PCNA expression in gingival cell cultures. The data suggest that HMGB1/RAGE axis has crucial roles in palatal wound healing.

A nano-microstructured artificial-hair-cell-type sensor based on topologically graded 3D carbon nanotube bundles

NASA Astrophysics Data System (ADS)

Yilmazoglu, O.; Yadav, S.; Cicek, D.; Schneider, J. J.

2016-09-01

A design for a unique artificial-hair-cell-type sensor (AHCTS) based entirely on 3D-structured, vertically aligned carbon nanotube (CNT) bundles is introduced. Standard microfabrication techniques were used for the straightforward micro-nano integration of vertically aligned carbon nanotube arrays composed of low-layer multi-walled CNTs (two to six layers). The mechanical properties of the carbon nanotube bundles were intensively characterized with regard to various substrates and CNT morphology, e.g. bundle height. The CNT bundles display excellent flexibility and mechanical stability for lateral bending, showing high tear resistance. The integrated 3D CNT sensor can detect three-dimensional forces using the deflection or compression of a central CNT bundle which changes the contact resistance to the shorter neighboring bundles. The complete sensor system can be fabricated using a single chemical vapor deposition (CVD) process step. Moreover, sophisticated external contacts to the surroundings are not necessary for signal detection. No additional sensors or external bias for signal detection are required. This simplifies the miniaturization and the integration of these nanostructures for future microsystem set-ups. The new nanostructured sensor system exhibits an average sensitivity of 2100 ppm in the linear regime with the relative resistance change per micron (ppm μm-1) of the individual CNT bundle tip deflection. Furthermore, experiments have shown highly sensitive piezoresistive behavior with an electrical resistance decrease of up to ˜11% at 50 μm mechanical deflection. The detection sensitivity is as low as 1 μm of deflection, and thus highly comparable with the tactile hair sensors of insects, having typical thresholds on the order of 30-50 μm. The AHCTS can easily be adapted and applied as a flow, tactile or acceleration sensor as well as a vibration sensor. Potential applications of the latter might come up in artificial cochlear systems. In particular, the stable mechanical bending of the sensor up to 90° opens up unique application opportunities.

Cell Based Therapeutic Approach in Vascular Surgery: Application and Review

PubMed Central

Rocca, Aldo; Tafuri, Domenico; Paccone, Marianna; Giuliani, Antonio; Zamboli, Anna Ginevra Immacolata; Surfaro, Giuseppe; Paccone, Andrea; Compagna, Rita; Amato, Maurizo; Serra, Raffaele; Amato, Bruno

2017-01-01

Abstract Multipotent stem cells - such as mesenchymal stem/stromal cells and stem cells derived from different sources like vascular wall are intensely studied to try to rapidly translate their discovered features from bench to bedside. Vascular wall resident stem cells recruitment, differentiation, survival, proliferation, growth factor production, and signaling pathways transduced were analyzed. We studied biological properties of vascular resident stem cells and explored the relationship from several factors as Matrix Metalloproteinases (MMPs) and regulations of biological, translational and clinical features of these cells. In this review we described a translational and clinical approach to Adult Vascular Wall Resident Multipotent Vascular Stem Cells (VW-SCs) and reported their involvement in alternative clinical approach as cells based therapy in vascular disease like arterial aneurysms or peripheral arterial obstructive disease. PMID:29071303

Infrared imaging spectrometry by the use of bundled chalcogenide glass fibers and a PtSi CCD camera

NASA Astrophysics Data System (ADS)

Saito, Mitsunori; Kikuchi, Katsuhiro; Tanaka, Chinari; Sone, Hiroshi; Morimoto, Shozo; Yamashita, Toshiharu T.; Nishii, Junji

1999-10-01

A coherent fiber bundle for infrared image transmission was prepared by arranging 8400 chalcogenide (AsS) glass fibers. The fiber bundle, 1 m in length, is transmissive in the infrared spectral region of 1 - 6 micrometer. A remote spectroscopic imaging system was constructed with the fiber bundle and an infrared PtSi CCD camera. The system was used for the real-time observation (frame time: 1/60 s) of gas distribution. Infrared light from a SiC heater was delivered to a gas cell through a chalcogenide fiber, and transmitted light was observed through the fiber bundle. A band-pass filter was used for the selection of gas species. A He-Ne laser of 3.4 micrometer wavelength was also used for the observation of hydrocarbon gases. Gases bursting from a nozzle were observed successfully by a remote imaging system.

Morphology, Growth, and Size Limit of Bacterial Cells

NASA Astrophysics Data System (ADS)

Jiang, Hongyuan; Sun, Sean X.

2010-07-01

Bacterial cells utilize a living peptidoglycan network (PG) to separate the cell interior from the surroundings. The shape of the cell is controlled by PG synthesis and cytoskeletal proteins that form bundles and filaments underneath the cell wall. The PG layer also resists turgor pressure and protects the cell from osmotic shock. We argue that mechanical influences alter the chemical equilibrium of the reversible PG assembly and determine the cell shape and cell size. Using a mechanochemical approach, we show that the cell shape can be regarded as a steady state of a growing network under the influence of turgor pressure and mechanical stress. Using simple elastic models, we predict the size of common spherical and rodlike bacteria. The influence of cytoskeletal bundles such as crescentin and MreB are discussed within the context of our model.

Quantitative Analysis of Statics and Dynamics of Actin Cables in Fission Yeast

NASA Astrophysics Data System (ADS)

Yusuf, Eddy; Wu, Jian-Qiu; Vavylonis, Dimitrios

2010-03-01

The assembly of actin and tubulin proteins into long filaments and bundles, i.e. closely-packed filaments, underlies important cellular processes such as cell motility, intracellular transport, and cell division. Recent theoretical and experimental work has addressed the nonequilibrium dynamics of single microtubules within live cells [1]. Actin filaments usually form dense networks that prevents microscopic imaging of individual filaments or bundles. Here, we studied actin dynamics using fission yeast that has low-density actin cytoskeleton consisting of actin cables (actin bundles aligned along the long axis of the cell) and ``actin patches.'' Yeast cells expressing GFP-CHD were imaged by 3D confocal microscopy. Stretching open active contours [2] were used to segment and track individual actin cables. We analyzed their curvature distribution, the tangent correlation, and the temporal bending amplitude fluctuations. We contrast our findings to equilibrium fluctuating semiflexible polymers and to microtubules in cells. We calculate the important time and length scales for the actin cables. We also discuss our findings within the broad context of understanding actin assembly in cells. [1] C. P. Brangwynne et. al., Phys. Rev. Lett. 100, 118104 (2008) [2] H. Li et. al., Proc. of the IEEE Int'l Symposium on Biomedical Imaging: From Nano to Macro, ISBI'09

Microscopic Analysis of Bacterial Motility at High Pressure

PubMed Central

Nishiyama, Masayoshi; Sowa, Yoshiyuki

2012-01-01

The bacterial flagellar motor is a molecular machine that converts an ion flux to the rotation of a helical flagellar filament. Counterclockwise rotation of the filaments allows them to join in a bundle and propel the cell forward. Loss of motility can be caused by environmental factors such as temperature, pH, and solvation. Hydrostatic pressure is also a physical inhibitor of bacterial motility, but the detailed mechanism of this inhibition is still unknown. Here, we developed a high-pressure microscope that enables us to acquire high-resolution microscopic images, regardless of applied pressures. We also characterized the pressure dependence of the motility of swimming Escherichia coli cells and the rotation of single flagellar motors. The fraction and speed of swimming cells decreased with increased pressure. At 80 MPa, all cells stopped swimming and simply diffused in solution. After the release of pressure, most cells immediately recovered their initial motility. Direct observation of the motility of single flagellar motors revealed that at 80 MPa, the motors generate torque that should be sufficient to join rotating filaments in a bundle. The discrepancy in the behavior of free swimming cells and individual motors could be due to the applied pressure inhibiting the formation of rotating filament bundles that can propel the cell body in an aqueous environment. PMID:22768943

Influence of carbon nanotubes on the buckling of microtubule bundles in viscoelastic cytoplasm using nonlocal strain gradient theory

NASA Astrophysics Data System (ADS)

Farajpour, A.; Rastgoo, A.

Carbon nanotubes are a new class of microtubule-stabilizing agents since they interact with protein microtubules in living cells, interfering with cell division and inducing apoptosis. In the present work, a modified beam model is developed to investigate the effect of carbon nanotubes on the buckling of microtubule bundles in living cell. A realistic interaction model is employed using recent experimental data on the carbon nanotube-stabilized microtubules. Small scale and surface effects are taken into account applying the nonlocal strain gradient theory and surface elasticity theory. Pasternak model is used to describe the normal and shearing effects of enclosing filament matrix on the buckling behavior of the system. An exact solution is obtained for the buckling growth rates of the mixed bundle in viscoelastic surrounding cytoplasm. The present results are compared with those reported in the open literature for single microtubules and an excellent agreement is found. Finally, the effects of different parameters such as the size, chirality, position and surface energy of carbon nanotubes on the buckling growth rates of microtubule bundles are studied. It is found that the buckling growth rate may increase or decrease by adding carbon nanotubes, depending on the diameter and chirality of carbon nanotubes.

Class III myosins shape the auditory hair bundles by limiting microvilli and stereocilia growth

PubMed Central

Lelli, Andrea; Michel, Vincent; Boutet de Monvel, Jacques; Cortese, Matteo; Bosch-Grau, Montserrat; Aghaie, Asadollah; Perfettini, Isabelle; Dupont, Typhaine; Avan, Paul

2016-01-01

The precise architecture of hair bundles, the arrays of mechanosensitive microvilli-like stereocilia crowning the auditory hair cells, is essential to hearing. Myosin IIIa, defective in the late-onset deafness form DFNB30, has been proposed to transport espin-1 to the tips of stereocilia, thereby promoting their elongation. We show that Myo3a−/−Myo3b−/− mice lacking myosin IIIa and myosin IIIb are profoundly deaf, whereas Myo3a-cKO Myo3b−/− mice lacking myosin IIIb and losing myosin IIIa postnatally have normal hearing. Myo3a−/−Myo3b−/− cochlear hair bundles display robust mechanoelectrical transduction currents with normal kinetics but show severe embryonic abnormalities whose features rapidly change. These include abnormally tall and numerous microvilli or stereocilia, ungraded stereocilia bundles, and bundle rounding and closure. Surprisingly, espin-1 is properly targeted to Myo3a−/−Myo3b−/− stereocilia tips. Our results uncover the critical role that class III myosins play redundantly in hair-bundle morphogenesis; they unexpectedly limit the elongation of stereocilia and of subsequently regressing microvilli, thus contributing to the early hair bundle shaping. PMID:26754646

Functional anatomy controls ion distribution in banana leaves: significance of Na+ seclusion at the leaf margins.

PubMed

Shapira, Or; Khadka, Sudha; Israeli, Yair; Shani, Uri; Schwartz, Amnon

2009-05-01

Typical salt stress symptoms appear in banana (Musa sp., cv. 'Grand Nain' AAA) only along the leaf margins. Mineral analysis of the dry matter of plants treated with increasing concentrations of KCl or NaCl revealed significant accumulation of Na+, but not of K+ or Cl(-), in the affected leaf margins. The differential distribution of the three ions suggests that water and ion movement out of the xylem is mostly symplastic and, in contrast to K+ and Cl(-), there exists considerable resistance to the flow of Na+ from the xylem to the adjacent mesophyll and epidermis. The parallel veins of the lamina are enclosed by several layers of bundle sheath parenchyma; in contrast, the large vascular bundle that encircles the entire lamina, and into which the parallel veins merge, lacks a complete bundle sheath. Xylem sap containing a high concentration of Na+ is 'pulled' by water tension from the marginal vein back into the adjacent mesophyll without having to cross a layer of parenchyma tissue. When the marginal vein was dissected from the lamina, the pattern of Na+ distribution in the margins changed markedly. The distinct anatomy of the marginal vein plays a major role in the accumulation of Na+ in the margins, with the latter serving as a 'dumping site' for toxic molecules.

The very large G-protein-coupled receptor VLGR1: a component of the ankle link complex required for the normal development of auditory hair bundles.

PubMed

McGee, Joann; Goodyear, Richard J; McMillan, D Randy; Stauffer, Eric A; Holt, Jeffrey R; Locke, Kirsten G; Birch, David G; Legan, P Kevin; White, Perrin C; Walsh, Edward J; Richardson, Guy P

2006-06-14

Sensory hair bundles in the inner ear are composed of stereocilia that can be interconnected by a variety of different link types, including tip links, horizontal top connectors, shaft connectors, and ankle links. The ankle link antigen is an epitope specifically associated with ankle links and the calycal processes of photoreceptors in chicks. Mass spectrometry and immunoblotting were used to identify this antigen as the avian ortholog of the very large G-protein-coupled receptor VLGR1, the product of the Usher syndrome USH2C (Mass1) locus. Like ankle links, Vlgr1 is expressed transiently around the base of developing hair bundles in mice. Ankle links fail to form in the cochleae of mice carrying a targeted mutation in Vlgr1 (Vlgr1/del7TM), and the bundles become disorganized just after birth. FM1-43 [N-(3-triethylammonium)propyl)-4-(4-(dibutylamino)styryl) pyridinium dibromide] dye loading and whole-cell recordings indicate mechanotransduction is impaired in cochlear, but not vestibular, hair cells of early postnatal Vlgr1/del7TM mutant mice. Auditory brainstem recordings and distortion product measurements indicate that these mice are severely deaf by the third week of life. Hair cells from the basal half of the cochlea are lost in 2-month-old Vlgr1/del7TM mice, and retinal function is mildly abnormal in aged mutants. Our results indicate that Vlgr1 is required for formation of the ankle link complex and the normal development of cochlear hair bundles.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chung, Peter J.; Song, Chaeyeon; Deek, Joanna

Tau, an intrinsically disordered protein confined to neuronal axons, binds to and regulates microtubule dynamics. Although there have been observations of string-like microtubule fascicles in the axon initial segment (AIS) and hexagonal bundles in neurite-like processes in non-neuronal cells overexpressing Tau, cell-free reconstitutions have not replicated either geometry. Here we map out the energy landscape of Tau-mediated, GTP-dependent ‘active’ microtubule bundles at 37°C, as revealed by synchrotron SAXS and TEM. Widely spaced bundles (wall-to-wall distance D w–w≈25–41nm) with hexagonal and string-like symmetry are observed, the latter mimicking bundles found in the AIS. A second energy minimum (D w–w≈16–23nm) is revealedmore » under osmotic pressure. The wide spacing results from a balance between repulsive forces, due to Tau’s projection domain (PD), and a stabilizing sum of transient sub-k BT cationic/anionic charge–charge attractions mediated by weakly penetrating opposing PDs. In the end, we find that this landscape would be significantly affected by charge-altering modifications of Tau associated with neurodegeneration.« less

Electrostatic interaction between stereocilia: I. Its role in supporting the structure of the hair bundle.

PubMed

Dolgobrodov, S G; Lukashkin, A N; Russell, I J

2000-12-01

This paper provides theoretical estimates for the forces of electrostatic interaction between adjacent stereocilia in auditory and vestibular hair cells. Estimates are given for parameters within the measured physiological range using constraints appropriate for the known geometry of the hair bundle. Stereocilia are assumed to possess an extended, negatively charged surface coat, the glycocalyx. Different charge distribution profiles within the glycocalyx are analysed. It is shown that charged glycocalices on the apical surface of the hair cells can support spatial separation between adjacent stereocilia in the hair bundles through electrostatic repulsion between stereocilia. The charge density profile within the glycocalyx is a crucial parameter. In fact, attraction instead of repulsion between adjacent stereocilia will be observed if the charge of the glycocalyx is concentrated near the membrane of the stereocilia, thereby making this type of charge distribution unlikely. The forces of electrostatic interaction between stereocilia may influence the mechanical properties of the hair bundle and, being strongly non-linear, contribute to the non-linear phenomena that have been recorded from the periphery of the auditory and vestibular systems.

High-resolution imaging of the retinal nerve fiber layer in normal eyes using adaptive optics scanning laser ophthalmoscopy.

PubMed

Takayama, Kohei; Ooto, Sotaro; Hangai, Masanori; Arakawa, Naoko; Oshima, Susumu; Shibata, Naohisa; Hanebuchi, Masaaki; Inoue, Takashi; Yoshimura, Nagahisa

2012-01-01

To conduct high-resolution imaging of the retinal nerve fiber layer (RNFL) in normal eyes using adaptive optics scanning laser ophthalmoscopy (AO-SLO). AO-SLO images were obtained in 20 normal eyes at multiple locations in the posterior polar area and a circular path with a 3-4-mm diameter around the optic disc. For each eye, images focused on the RNFL were recorded and a montage of AO-SLO images was created. AO-SLO images for all eyes showed many hyperreflective bundles in the RNFL. Hyperreflective bundles above or below the fovea were seen in an arch from the temporal periphery on either side of a horizontal dividing line to the optic disc. The dark lines among the hyperreflective bundles were narrower around the optic disc compared with those in the temporal raphe. The hyperreflective bundles corresponded with the direction of the striations on SLO red-free images. The resolution and contrast of the bundles were much higher in AO-SLO images than in red-free fundus photography or SLO red-free images. The mean hyperreflective bundle width around the optic disc had a double-humped shape; the bundles at the temporal and nasal sides of the optic disc were narrower than those above and below the optic disc (P<0.001). RNFL thickness obtained by optical coherence tomography correlated with the hyperreflective bundle widths on AO-SLO (P<0.001) AO-SLO revealed hyperreflective bundles and dark lines in the RNFL, believed to be retinal nerve fiber bundles and Müller cell septa. The widths of the nerve fiber bundles appear to be proportional to the RNFL thickness at equivalent distances from the optic disc.

Micro-PIXE investigation of bean seeds to assist micronutrient biofortification

NASA Astrophysics Data System (ADS)

Cvitanich, Cristina; Przybyłowicz, Wojciech J.; Mesjasz-Przybyłowicz, Jolanta; Blair, Matthew W.; Astudillo, Carolina; Orłowska, Elżbieta; Jurkiewicz, Anna M.; Jensen, Erik Ø.; Stougaard, Jens

2011-10-01

This study compares the distribution and concentrations of micro- and macronutrients in different bean cultivars with the aim of optimizing the biofortification, a sustainable approach towards improving dietary quality. Micro-PIXE was used to reveal the distribution of Fe, Zn, Mn, Ca, P, S in seeds of common beans (Phaseolus vulgaris) and runner beans (Phaseolus coccineus). Average concentrations of elements in different tissues were obtained using ICP-AES. The highest concentrations of Zn in the studied beans were found in the embryonic axis, but an increased concentration of this element was also detected in the provascular bundles of the cotyledons. The first layer of cells surrounding provascular bundles accumulated high concentrations of Fe, while the next cell layer had an increased concentration of Mn. The analysis showed that the provascular bundles and the first cell layers surrounding them could have a significant role in the storage of important seed micronutrients - Zn, Fe, and Mn. This information has important implications for molecular biology studies aimed at seed biofortification.

Artificial hair cell integrated with an artificial neuron: Interplay between criticality and excitability

NASA Astrophysics Data System (ADS)

Lee, Woo Seok; Jeong, Wonhee; Ahn, Kang-Hun

2014-12-01

We provide a simple dynamical model of a hair cell with an afferent neuron where the spectral and the temporal responses are controlled by the hair bundle's criticality and the neuron's excitability. To demonstrate that these parameters, indeed, specify the resolution of the sound encoding, we fabricate a neuromorphic device that models the hair cell bundle and its afferent neuron. Then, we show that the neural response of the biomimetic system encodes sounds with either high temporal or spectral resolution or with a combination of both resolutions. Our results suggest that the hair cells may easily specialize to fulfil various roles in spite of their similar physiological structures.

A structural review of foliar glands in Passiflora L. (Passifloraceae)

PubMed Central

da Costa Silva, Delmira; Flavia de Albuquerque Melo-de-Pinna, Gladys

2017-01-01

Extrafloral glands in Passifloraceae species have aroused the interest of many researchers because of their wide morphological diversity. The present work analyzed the foliar glands on 34 species of Passiflora from samples containing glands in the petiole and foliar blade fixed in 50% solution of formaldehyde-ethanol-acetic acid and stored in a 70% ethanol solution. For anatomical analyses, part of the material was embedded in Paraplast, longitudinally sectioned and double stained with safranin and astra blue. Scanning electron microscopy analysis was also carried out. To analyze the presence of sugars in the secretion of foliar glands, a glucose strip test was used. Based on the results of morphological, anatomical and glucose strip tests, the foliar secretory glands in Passiflora can be grouped into two categories: Type I glands, defined as nectaries, can be elevated or flattened, and can have a sugar content high enough to be detected by the glucose strip test analysis. Type II glands are elevated and did not show a positive reaction to the glucose strip test. From an anatomical viewpoint, glands characterized as extrafloral nectaries show a multistratified secretory epidermis, typically followed by two flat layers of nectariferous parenchyma with dense content. Internal to these layers, vascular bundles are immersed in the subsecretory parenchyma and terminate in phloem cells. On the other hand, type II glands show a single layer of elongated secretory epidermal cells. Internal to this single layer, parenchyma and vascular tissue with both phloem and xylem elements can be observed. The analyzed species show a wide diversity of gland shape and distribution, and the combined analysis of morphology, anatomy and preliminary tests for the presence of glucose in the exudate in different Passiflora subgenera suggests the occurrence of two categories of glands: nectaries and resin glands. PMID:29136029

Function of glutathione peroxidases in legume root nodules.

PubMed

Matamoros, Manuel A; Saiz, Ana; Peñuelas, Maria; Bustos-Sanmamed, Pilar; Mulet, Jose M; Barja, Maria V; Rouhier, Nicolas; Moore, Marten; James, Euan K; Dietz, Karl-Josef; Becana, Manuel

2015-05-01

Glutathione peroxidases (Gpxs) are antioxidant enzymes not studied so far in legume nodules, despite the fact that reactive oxygen species are produced at different steps of the symbiosis. The function of two Gpxs that are highly expressed in nodules of the model legume Lotus japonicus was examined. Gene expression analysis, enzymatic and nitrosylation assays, yeast cell complementation, in situ mRNA hybridization, immunoelectron microscopy, and LjGpx-green fluorescent protein (GFP) fusions were used to characterize the enzymes and to localize each transcript and isoform in nodules. The LjGpx1 and LjGpx3 genes encode thioredoxin-dependent phospholipid hydroperoxidases and are differentially regulated in response to nitric oxide (NO) and hormones. LjGpx1 and LjGpx3 are nitrosylated in vitro or in plants treated with S-nitrosoglutathione (GSNO). Consistent with the modification of the peroxidatic cysteine of LjGpx3, in vitro assays demonstrated that this modification results in enzyme inhibition. The enzymes are highly expressed in the infected zone, but the LjGpx3 mRNA is also detected in the cortex and vascular bundles. LjGpx1 is localized to the plastids and nuclei, and LjGpx3 to the cytosol and endoplasmic reticulum. Based on yeast complementation experiments, both enzymes protect against oxidative stress, salt stress, and membrane damage. It is concluded that both LjGpxs perform major antioxidative functions in nodules, preventing lipid peroxidation and other oxidative processes at different subcellular sites of vascular and infected cells. The enzymes are probably involved in hormone and NO signalling, and may be regulated through nitrosylation of the peroxidatic cysteine essential for catalytic function. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Optical imaging of neural and hemodynamic brain activity

NASA Astrophysics Data System (ADS)

Schei, Jennifer Lynn

Optical imaging technologies can be used to record neural and hemodynamic activity. Neural activity elicits physiological changes that alter the optical tissue properties. Specifically, changes in polarized light are concomitant with neural depolarization. We measured polarization changes from an isolated lobster nerve during action potential propagation using both reflected and transmitted light. In transmission mode, polarization changes were largest throughout the center of the nerve, suggesting that most of the optical signal arose from the inner nerve bundle. In reflection mode, polarization changes were largest near the edges, suggesting that most of the optical signal arose from the outer sheath. To overcome irregular cell orientation found in the brain, we measured polarization changes from a nerve tied in a knot. Our results show that neural activation produces polarization changes that can be imaged even without regular cell orientations. Neural activation expends energy resources and elicits metabolic delivery through blood vessel dilation, increasing blood flow and volume. We used spectroscopic imaging techniques combined with electrophysiological measurements to record evoked neural and hemodynamic responses from the auditory cortex of the rat. By using implantable optics, we measured responses across natural wake and sleep states, as well as responses following different amounts of sleep deprivation. During quiet sleep, evoked metabolic responses were larger compared to wake, perhaps because blood vessels were more compliant. When animals were sleep deprived, evoked hemodynamic responses were smaller following longer periods of deprivation. These results suggest that prolonged neural activity through sleep deprivation may diminish vascular compliance as indicated by the blunted vascular response. Subsequent sleep may allow vessels to relax, restoring their ability to deliver blood. These results also suggest that severe sleep deprivation or chronic sleep disturbances could push the vasculature to critical limits, leading to metabolic deficit and the potential for tissue trauma.

Development of the nervous system in Phoronopsis harmeri (Lophotrochozoa, Phoronida) reveals both deuterostome- and trochozoan-like features

PubMed Central

2012-01-01

Background Inferences concerning the evolution of invertebrate nervous systems are often hampered by the lack of a solid data base for little known but phylogenetically crucial taxa. In order to contribute to the discussion concerning the ancestral neural pattern of the Lophotrochozoa (a major clade that includes a number of phyla that exhibit a ciliated larva in their life cycle), we investigated neurogenesis in Phoronopsis harmeri, a member of the poorly studied Phoronida, by using antibody staining against serotonin and FMRFamide in combination with confocal microscopy and 3D reconstruction software. Results The larva of Phoronopsis harmeri exhibits a highly complex nervous system, including an apical organ that consists of four different neural cell types, such as numerous serotonin-like immunoreactive flask-shaped cells. In addition, serotonin- and FMRFamide-like immunoreactive bi- or multipolar perikarya that give rise to a tentacular neurite bundle which innervates the postoral ciliated band are found. The preoral ciliated band is innervated by marginal serotonin-like as well as FMRFamide-like immunoreactive neurite bundles. The telotroch is innervated by two neurite bundles. The oral field is the most densely innervated area and contains ventral and ventro-lateral neurite bundles as well as several groups of perikarya. The digestive system is innervated by both serotonin- and FMRFamide-like immunoreactive neurites and perikarya. Importantly, older larvae of P. harmeri show a paired ventral neurite bundle with serial commissures and perikarya. Conclusions Serotonin-like flask-shaped cells such as the ones described herein for Phoronopsis harmeri are found in the majority of lophotrochozoan larvae and therefore most likely belong to the ground pattern of the last common lophotrochozoan ancestor. The finding of a transitory paired ventral neurite bundle with serially repeated commissures that disappears during metamorphosis suggests that such a structure was part of the “ur-phoronid” nervous system, but was lost in the adult stage, probably due to its acquired sessile benthic lifestyle. PMID:22827441

Vascular Wall-Resident Multipotent Stem Cells of Mesenchymal Nature within the Process of Vascular Remodeling: Cellular Basis, Clinical Relevance, and Implications for Stem Cell Therapy.

PubMed

Klein, Diana

2016-01-01

Until some years ago, the bone marrow and the endothelial cell compartment lining the vessel lumen (subendothelial space) were thought to be the only sources providing vascular progenitor cells. Now, the vessel wall, in particular, the vascular adventitia, has been established as a niche for different types of stem and progenitor cells with the capacity to differentiate into both vascular and nonvascular cells. Herein, vascular wall-resident multipotent stem cells of mesenchymal nature (VW-MPSCs) have gained importance because of their large range of differentiation in combination with their distribution throughout the postnatal organism which is related to their existence in the adventitial niche, respectively. In general, mesenchymal stem cells, also designated as mesenchymal stromal cells (MSCs), contribute to the maintenance of organ integrity by their ability to replace defunct cells or secrete cytokines locally and thus support repair and healing processes of the affected tissues. This review will focus on the central role of VW-MPSCs within vascular reconstructing processes (vascular remodeling) which are absolute prerequisite to preserve the sensitive relationship between resilience and stability of the vessel wall. Further, a particular advantage for the therapeutic application of VW-MPSCs for improving vascular function or preventing vascular damage will be discussed.

The role of plasma membrane aquaporins in regulating the bundle sheath-mesophyll continuum and leaf hydraulics.

PubMed

Sade, Nir; Shatil-Cohen, Arava; Attia, Ziv; Maurel, Christophe; Boursiac, Yann; Kelly, Gilor; Granot, David; Yaaran, Adi; Lerner, Stephen; Moshelion, Menachem

2014-11-01

Our understanding of the cellular role of aquaporins (AQPs) in the regulation of whole-plant hydraulics, in general, and extravascular, radial hydraulic conductance in leaves (K(leaf)), in particular, is still fairly limited. We hypothesized that the AQPs of the vascular bundle sheath (BS) cells regulate K(leaf). To examine this hypothesis, AQP genes were silenced using artificial microRNAs that were expressed constitutively or specifically targeted to the BS. MicroRNA sequences were designed to target all five AQP genes from the PLASMA MEMBRANE-INTRINSIC PROTEIN1 (PIP1) subfamily. Our results show that the constitutively silenced PIP1 (35S promoter) plants had decreased PIP1 transcript and protein levels and decreased mesophyll and BS osmotic water permeability (P(f)), mesophyll conductance of CO2, photosynthesis, K(leaf), transpiration, and shoot biomass. Plants in which the PIP1 subfamily was silenced only in the BS (SCARECROW:microRNA plants) exhibited decreased mesophyll and BS Pf and decreased K(leaf) but no decreases in the rest of the parameters listed above, with the net result of increased shoot biomass. We excluded the possibility of SCARECROW promoter activity in the mesophyll. Hence, the fact that SCARECROW:microRNA mesophyll exhibited reduced P(f), but not reduced mesophyll conductance of CO2, suggests that the BS-mesophyll hydraulic continuum acts as a feed-forward control signal. The role of AQPs in the hierarchy of the hydraulic signal pathway controlling leaf water status under normal and limited-water conditions is discussed. © 2014 American Society of Plant Biologists. All Rights Reserved.

Vinpocetine Attenuates the Osteoblastic Differentiation of Vascular Smooth Muscle Cells.

PubMed

Ma, Yun-Yun; Sun, Lin; Chen, Xiu-Juan; Wang, Na; Yi, Peng-Fei; Song, Min; Zhang, Bo; Wang, Yu-Zhong; Liang, Qiu-Hua

2016-01-01

Vascular calcification is an active process of osteoblastic differentiation of vascular smooth muscle cells; however, its definite mechanism remains unknown. Vinpocetine, a derivative of the alkaloid vincamine, has been demonstrated to inhibit the high glucose-induced proliferation of vascular smooth muscle cells; however, it remains unknown whether vinpocetine can affect the osteoblastic differentiation of vascular smooth muscle cells. We hereby investigated the effect of vinpocetine on vascular calcification using a beta-glycerophosphate-induced cell model. Our results showed that vinpocetine significantly reduced the osteoblast-like phenotypes of vascular smooth muscle cells including ALP activity, osteocalcin, collagen type I, Runx2 and BMP-2 expression as well as the formation of mineralized nodule. Vinpocetine, binding to translocation protein, induced phosphorylation of extracellular signal-related kinase and Akt and thus inhibited the translocation of nuclear factor-kappa B into the nucleus. Silencing of translocator protein significantly attenuated the inhibitory effect of vinpocetine on osteoblastic differentiation of vascular smooth muscle cells. Taken together, vinpocetine may be a promising candidate for the clinical therapy of vascular calcification.

Development of basal endosperm transfer cells in Sorghum bicolor (L.) Moench and its relationship with caryopsis growth.

PubMed

Wang, Hui-Hui; Wang, Zhong; Wang, Feng; Gu, Yun-Jie; Liu, Zhi

2012-04-01

During sorghum caryopsis development, endosperm epidermal cells near the basal main vascular bundle are specialized by depositing wall ingrowths, differentiating into basal endosperm transfer cells (BETCs). All the BETCs together compose the basal endosperm transfer layer (BETL). BETCs are the first cell type to become histologically differentiated during endosperm development. The initiation and subsequent development of BETCs shows the pattern of temporal and spatial gradient. The developmental process of BETL can be divided into four stages: initiation, differentiation, functional, and apoptosis stage. A placental sac full of nutrient solutions would emerge, enlarge, and eventually disappear between the outmost layer of BETL and nucellar cells during caryopsis development. BETCs have dense cytoplasm rich in mitochondria, lamellar rough endoplasmic reticulum, Golgi bodies, and their secretory vesicles. They show a series of typical characteristics of senescence such as nuclei distortion and subcellular organelle deterioration during their specialization. BETCs probably play an active role in nutrient transfer into the starchy endosperm and embryo. The occurrence, development, and apoptosis of BETCs are in close relation to the caryopsis growth and maturation especially the enrichment of endosperm and the growth of embryo. The timing when BETL is fully developed, composed of three to four layers in radial direction and 70 to 80 rows in tangential direction, consists with the timing when average daily gain of caryopsis dry weight reaches its maximum. It is conceivable that measures that delay the senescence and death of BETCs would help to increase the crop yield.

Nano- and microstructured materials for in vitro studies of the physiology of vascular cells

PubMed Central

Chen, Hao; Biela, Sarah A; Kaufmann, Dieter

2016-01-01

The extracellular environment of vascular cells in vivo is complex in its chemical composition, physical properties, and architecture. Consequently, it has been a great challenge to study vascular cell responses in vitro, either to understand their interaction with their native environment or to investigate their interaction with artificial structures such as implant surfaces. New procedures and techniques from materials science to fabricate bio-scaffolds and surfaces have enabled novel studies of vascular cell responses under well-defined, controllable culture conditions. These advancements are paving the way for a deeper understanding of vascular cell biology and materials–cell interaction. Here, we review previous work focusing on the interaction of vascular smooth muscle cells (SMCs) and endothelial cells (ECs) with materials having micro- and nanostructured surfaces. We summarize fabrication techniques for surface topographies, materials, geometries, biochemical functionalization, and mechanical properties of such materials. Furthermore, various studies on vascular cell behavior and their biological responses to micro- and nanostructured surfaces are reviewed. Emphasis is given to studies of cell morphology and motility, cell proliferation, the cytoskeleton and cell-matrix adhesions, and signal transduction pathways of vascular cells. We finalize with a short outlook on potential interesting future studies. PMID:28144512

Proteome Analysis of Watery Saliva Secreted by Green Rice Leafhopper, Nephotettix cincticeps

PubMed Central

Hattori, Makoto; Komatsu, Setsuko; Noda, Hiroaki; Matsumoto, Yukiko

2015-01-01

The green rice leafhopper, Nephotettix cincticeps, is a vascular bundle feeder that discharges watery and gelling saliva during the feeding process. To understand the potential functions of saliva for successful and safe feeding on host plants, we analyzed the complexity of proteinaceous components in the watery saliva of N. cincticeps. Salivary proteins were collected from a sucrose diet that adult leafhoppers had fed on through a membrane of stretched parafilm. Protein concentrates were separated using SDS-PAGE under reducing and non-reducing conditions. Six proteins were identified by a gas-phase protein sequencer and two proteins were identified using LC-MS/MS analysis with reference to expressed sequence tag (EST) databases of this species. Full -length cDNAs encoding these major proteins were obtained by rapid amplification of cDNA ends-PCR (RACE-PCR) and degenerate PCR. Furthermore, gel-free proteome analysis that was performed to cover the broad range of salivary proteins with reference to the latest RNA-sequencing data from the salivary gland of N. cincticeps, yielded 63 additional protein species. Out of 71 novel proteins identified from the watery saliva, about 60 % of those were enzymes or other functional proteins, including GH5 cellulase, transferrin, carbonic anhydrases, aminopeptidase, regucalcin, and apolipoprotein. The remaining proteins appeared to be unique and species- specific. This is the first study to identify and characterize the proteins in watery saliva of Auchenorrhyncha species, especially sheath-producing, vascular bundle-feeders. PMID:25909947

Divergent metabolome and proteome suggest functional independence of dual phloem transport systems in cucurbits

PubMed Central

Zhang, Baichen; Tolstikov, Vladimir; Turnbull, Colin; Hicks, Leslie M.; Fiehn, Oliver

2010-01-01

Cucurbitaceous plants (cucurbits) have long been preferred models for studying phloem physiology. However, these species are unusual in that they possess two different phloem systems, one within the main vascular bundles [fascicular phloem (FP)] and another peripheral to the vascular bundles and scattered through stem and petiole cortex tissues [extrafascicular phloem (EFP)]. We have revisited the assumption that the sap released after shoot incision originates from the FP, and also investigated the long-standing question of why the sugar content of this sap is ~30-fold less than predicted for requirements of photosynthate delivery. Video microscopy and phloem labeling experiments unexpectedly reveal that FP very quickly becomes blocked upon cutting, whereas the extrafascicular phloem bleeds for extended periods. Thus, all cucurbit phloem sap studies to date have reported metabolite, protein, and RNA composition and transport in the relatively minor extrafascicular sieve tubes. Using tissue dissection and direct sampling of sieve tube contents, we show that FP in fact does contain up to 1 M sugars, in contrast to low-millimolar levels in the EFP. Moreover, major phloem proteins in sieve tubes of FP differ from those that predominate in the extrafascicular sap, and include several previously uncharacterized proteins with little or no homology to databases. The overall compositional differences of the two phloem systems strongly indicate functional isolation. On this basis, we propose that the fascicular phloem is largely responsible for sugar transport, whereas the extrafascicular phloem may function in signaling, defense, and transport of other metabolites. PMID:20566864

Motility of vestibular hair cells in the chick.

PubMed

Ogata, Y; Sekitani, T

1993-01-01

Recent studies of the outer hair cells in cochlea have demonstrated active motilities. However, very little study has been done on the vestibular hair cells (VHCs). The present study shows the motile response of the VHCs induced by application of Ca2+/ATP promoting contraction. Reversible cell shape changes could be shown in 10 of 16 isolated type I hair cells and 9 of 15 isolated type II hair cells by applying the contraction solution. Furthermore, the sensory hair bundles in the utricular epithelium pivoted around the base and stood perpendicularly to the apical borderline of the epithelium in response to the application of the same solution. It is suggested that the contraction of the isolated VHCs may be transferred to tension which causes the sensory hair bundles to restrict their motion in normal tissue, instead of changing the cell shape.

Schwann Cell Phenotype Changes in Aging Human Dental Pulp.

PubMed

Couve, E; Lovera, M; Suzuki, K; Schmachtenberg, O

2018-03-01

Schwann cells are glial cells that support axonal development, maintenance, defense, and regeneration in the peripheral nervous system. There is limited knowledge regarding the organization, plasticity, and aging of Schwann cells within the dental pulp in adult permanent teeth. The present study sought to relate changes in the pattern of Schwann cell phenotypes between young and old adult teeth with neuronal, immune, and vascular components of the dental pulp. Schwann cells are shown to form a prominent glial network at the dentin-pulp interface, consisting of nonmyelinating and myelinating phenotypes, forming a multicellular neuroimmune interface in association with nerve fibers and dendritic cells. Schwann cell phenotypes are recognized by the expression of S100, glial fibrillary acidic protein (GFAP), myelin basic protein (MBP), Sox10, GAP43, and p75NTR markers. In young adult teeth, a dense population of nonmyelinating Schwann cells projects processes in close association with sensory nerve terminals through the odontoblast layer, reaching the adjacent predentin/dentin domain. While GAP43 and p75NTR are highly expressed in nonmyelinating Schwann cells from young adult teeth, the presence of these markers declines significantly in old adult teeth. Myelinated axons, identified by MBP expression, are mainly present at the Raschkow plexus and within nerve bundles in the dental pulp, but their density is significantly reduced in old adult versus young adult teeth. These data reveal age-related changes within the glial network of the dental pulp, in association with a reduction of coronal dental pulp innervation in old adult versus young adult teeth. The prominence of Schwann cells as a cellular component at the dentin-pulp interface supports the notion that their association with sensory nerve terminals and immune system components forms part of an integrated multicellular barrier for defense against pathogens and dentin repair.

Localization and pattern of graviresponse across the pulvinus of barley Hordeum vulgare

NASA Technical Reports Server (NTRS)

Brock, T. G.; Lu, C. R.; Ghosheh, N. S.; Kaufman, P. B.

1989-01-01

Pulvini of excised stem segments from barley (Hordeum vulgare cv Larker') were pretreated with 1 millimolar coumarin before gravistimulation to reduce longitudinal cell expansion and exaggerate radial cell enlargement. The cellular localization and pattern of graviresponse across individual pulvini were then evaluated by cutting the organ in cross-section, photographing the cross-section, and then measuring pulvinus thickness and the radial width of cortical and epidermal cells in enlargements of the photomicrographs. With respect to orientation during gravistimulation, we designated the uppermost point of the cross-section 0 degrees and the lowermost point 180 degrees. A gravity-induced increase in pulvinus thickness was observable within 40 degrees of the vertical in coumarin-treated pulvini. In upper halves of coumarin-treated gravistimulated pulvini, cells in the inner cortex and inner epidermis had increased radial widths, relative to untreated gravistimulated pulvini. In lower halves of coumarin-treated pulvini, cells in the central and outer cortex and in the outer epidermis showed the greatest increase in radial width. Cells comprising the vascular bundles also increased in radial width, with this pattern following that of the central cortex. These results indicate (a) that all cell types are capable of showing a graviresponse, (b) that the graviresponse occurs in both the top and the bottom of the responding organ, and (c) that the magnitude of the response increases approximately linearly from the uppermost point to the lowermost. These results are also consistent with models of gravitropism that link the pattern and magnitude of the graviresponse to graviperception via statolith sedimentation.

Effects of different fixation and freeze substitution methods on the ultrastructural preservation of ZYMV-infected Cucurbita pepo (L.) leaves.

PubMed

Zechmann, Bernd; Müller, Maria; Zellnig, Günther

2005-08-01

Different fixation protocols [chemical fixation, plunge and high pressure freezing (HPF)] were used to study the effects of Zucchini yellow mosaic virus (ZYMV) disease on the ultrastructure of adult leaves of Styrian oil pumpkin plants (Cucurbita pepo L. subsp. pepo var. styriaca Greb.) with the transmission electron microscope. Additionally, different media were tested for freeze substitution (FS) to evaluate differences in the ultrastructural preservation of cryofixed plant leaf cells. FS was either performed in (i) 2% osmium tetroxide in anhydrous acetone containing 0.2% uranyl acetate, (ii) 0.01% safranin in anhydrous acetone, (iii) 0.5% glutaraldehyde in anhydrous acetone or (iv) anhydrous acetone. No ultrastructural differences were found in well-preserved cells of plunge and high pressure frozen samples. Cryofixed cells showed a finer granulated cytosol and smoother membranes, than what was found in chemically fixed samples. HPF led in comparison to plunge frozen plant material to an excellent preservation of vascular bundle cells. The use of FS-media such as anhydrous acetone, 0.01% safranin and 0.5% glutaraldehyde led to low membrane contrast and did not preserve the inner fine structures of mitochondria. Additionally, the use of 0.5% glutaraldehyde caused the cytosol to be fuzzy and partly loosened. ZYMV-induced ultrastructural alterations like cylindrical inclusions and dilated ER-cisternae did not differ between chemically fixed and cryofixed cells and were found within the cytosol of infected leaf cells and within sieve tube elements. The results demonstrate specific structural differences depending on the FS-medium used, which has to be considered for investigations of selected cell structures.

Wood as inspiration for new stimuli-responsive structures and materials

Treesearch

Joseph E. Jakes; Nayomi Plaza-Rodriguez; Samuel L. Zelinka; Donald S. Stone; Sophie-Charlotte Gleber; Stefan Vogt

2014-01-01

Nature has often provided inspiration for new smart structures and materials. Recently, we showed a bundle of a few wood cells are moisture-activated torsional actuators that can reversibly twist multiple revolutions per centimeter of length. The bundles produce specific torque higher than that produced by electric motors and possess shape memory twist capabilities....

Heavy metal accumulation imparts structural differences in fragrant Rosa species irrigated with marginal quality water.

PubMed

Ahsan, Muhammad; Younis, Adnan; Jaskani, Muhammad Jafar; Tufail, Aasma; Riaz, Atif; Schwinghamer, Timothy; Tariq, Usman; Nawaz, Fahim

2018-09-15

Wastewater is an alternative to traditional sources of renewable irrigation water in agriculture, particularly in water-scarce regions. However, the possible risks due to heavy metals accumulation in plant tissues are often overlooked by producers. The present study aimed to identify heavy metals-induced structural modifications to roots of scented Rosa species that were irrigated with water of marginal quality. The chemical and mineral contents from the experimental irrigation canal water (control) and treated wastewater were below the limits recommended by the Pakistan Environmental Protection Agency (Pak-EPA) for medicinal plants. The experimentally untreated wastewater contained electrical conductivity (EC), chemical oxygen demand (COD), biological oxygen demand (BOD), and heavy metals (Co, Cu, Cd, Pb) that were above the recommended limits. The responses by wastewater-treated Rosa species (Rosa damascena, R. bourboniana, R. Gruss-an-Teplitz, and R. centifolia) were evaluated. The experimental data revealed that treated wastewater significantly increased the thickness of collenchyma (cortex and pith) and parenchyma tissues (vascular bundle, xylem, and phloem) of R. Gruss-an-Teplitz. Root dermal tissues (epidermis) of R. bourboniana also responded to treated wastewater. R. damascena and R. centifolia were the least affected species, under the experimental irrigation conditions. Collenchyma and dermal tissues were thicker in R. damascena and R. Gruss-an-Teplitz under untreated wastewater conditions. In parenchyma tissues, vascular bundles were thicker in R. damascena in untreated wastewater conditions, while the xylem and phloem of R. Gruss-an-Teplitz were thicker where treated wastewater was applied. In tissues other than the vascular bundle, the differences in anatomical metrics due to the experimental irrigation treatments were greater during the second year of the experiment than in the first year. The contents of metals other than chromium in the roots and stems of roses were below the WHO limits, under all of the experimental irrigation conditions. Rosa centifolia contained higher heavy metals content than the other experimental species, and heavy metals content was associated with anatomical changes due to the treatments. We conclude that, under conditions of wastewater irrigation, R. Gruss-an-Teplitz was highly resistant; R. damascena was moderately resistant while R. bourboniana and R. centifolia were the most susceptible to irrigation with marginal quality water. This is the first report of plant tissue responses to wastewater irrigation by the experimental species. Regarding the accumulation of heavy metals in rose plant tissues, the results confirm that untreated wastewater must be treated to grow Rosa species where water is scarce. Copyright © 2018 Elsevier Inc. All rights reserved.

High-resolution confocal imaging of wall ingrowth deposition in plant transfer cells: Semi-quantitative analysis of phloem parenchyma transfer cell development in leaf minor veins of Arabidopsis.

PubMed

Nguyen, Suong T T; McCurdy, David W

2015-04-23

Transfer cells (TCs) are trans-differentiated versions of existing cell types designed to facilitate enhanced membrane transport of nutrients at symplasmic/apoplasmic interfaces. This transport capacity is conferred by intricate wall ingrowths deposited secondarily on the inner face of the primary cell wall, hence promoting the potential trans-membrane flux of solutes and consequently assigning TCs as having key roles in plant growth and productivity. However, TCs are typically positioned deep within tissues and have been studied mostly by electron microscopy. Recent advances in fluorophore labelling of plant cell walls using a modified pseudo-Schiff-propidium iodide (mPS-PI) staining procedure in combination with high-resolution confocal microscopy have allowed visualization of cellular details of individual tissue layers in whole mounts, hence enabling study of tissue and cellular architecture without the need for tissue sectioning. Here we apply a simplified version of the mPS-PI procedure for confocal imaging of cellulose-enriched wall ingrowths in vascular TCs at the whole tissue level. The simplified mPS-PI staining procedure produced high-resolution three-dimensional images of individual cell types in vascular bundles and, importantly, wall ingrowths in phloem parenchyma (PP) TCs in minor veins of Arabidopsis leaves and companion cell TCs in pea. More efficient staining of tissues was obtained by replacing complex clearing procedures with a simple post-fixation bleaching step. We used this modified procedure to survey the presence of PP TCs in other tissues of Arabidopsis including cotyledons, cauline leaves and sepals. This high-resolution imaging enabled us to classify different stages of wall ingrowth development in Arabidopsis leaves, hence enabling semi-quantitative assessment of the extent of wall ingrowth deposition in PP TCs at the whole leaf level. Finally, we conducted a defoliation experiment as an example of using this approach to statistically analyze responses of PP TC development to leaf ablation. Use of a modified mPS-PI staining technique resulted in high-resolution confocal imaging of polarized wall ingrowth deposition in TCs. This technique can be used in place of conventional electron microscopy and opens new possibilities to study mechanisms determining polarized deposition of wall ingrowths and use reverse genetics to identify regulatory genes controlling TC trans-differentiation.

Determination of the turbulence integral model parameters for a case of a coolant angular flow in regular rod-bundle

NASA Astrophysics Data System (ADS)

Bayaskhalanov, M. V.; Vlasov, M. N.; Korsun, A. S.; Merinov, I. G.; Philippov, M. Ph

2017-11-01

Research results of “k-ε” turbulence integral model (TIM) parameters dependence on the angle of a coolant flow in regular smooth cylindrical rod-bundle are presented. TIM is intended for the definition of efficient impulse and heat transport coefficients in the averaged equations of a heat and mass transfer in the regular rod structures in an anisotropic porous media approximation. The TIM equations are received by volume-averaging of the “k-ε” turbulence model equations on periodic cell of rod-bundle. The water flow across rod-bundle under angles from 15 to 75 degrees was simulated by means of an ANSYS CFX code. Dependence of the TIM parameters on flow angle was as a result received.

Nestin upregulation characterizes vascular remodeling secondary to hypertension in the rat.

PubMed

Tardif, Kim; Hertig, Vanessa; Duquette, Natacha; Villeneuve, Louis; El-Hamamsy, Ismail; Tanguay, Jean-François; Calderone, Angelino

2015-05-15

Proliferation and hypertrophy of vascular smooth muscle cells represent hallmark features of vessel remodeling secondary to hypertension. The intermediate filament protein nestin was recently identified in vascular smooth muscle cells and in other cell types directly participated in proliferation. The present study tested the hypothesis that vessel remodeling secondary to hypertension was characterized by nestin upregulation in vascular smooth muscle cells. Two weeks after suprarenal abdominal aorta constriction of adult male Sprague-Dawley rats, elevated mean arterial pressure increased the media area and thickness of the carotid artery and aorta and concomitantly upregulated nestin protein levels. In the normal adult rat carotid artery, nestin immunoreactivity was observed in a subpopulation of vascular smooth muscle cells, and the density significantly increased following suprarenal abdominal aorta constriction. Filamentous nestin was detected in cultured rat carotid artery- and aorta-derived vascular smooth muscle cells and an analogous paradigm observed in human aorta-derived vascular smooth muscle cells. ANG II and EGF treatment of vascular smooth muscle cells stimulated DNA and protein synthesis and increased nestin protein levels. Lentiviral short-hairpin RNA-mediated nestin depletion of carotid artery-derived vascular smooth muscle cells inhibited peptide growth factor-stimulated DNA synthesis, whereas protein synthesis remained intact. These data have demonstrated that vessel remodeling secondary to hypertension was characterized in part by nestin upregulation in vascular smooth muscle cells. The selective role of nestin in peptide growth factor-stimulated DNA synthesis has revealed that the proliferative and hypertrophic responses of vascular smooth muscle cells were mediated by divergent signaling events. Copyright © 2015 the American Physiological Society.

Comparative transduction mechanisms of hair cells in the bullfrog utriculus. 1: Responses to intracellular current

NASA Technical Reports Server (NTRS)

Baird, Richard A.

1994-01-01

Hair cells in the bullfrog sacculus are specifically adapted to sense small-amplitude, high-frequency linear accelerations. These hair cells display many properties that are undesirable or inappropriate for hair cells that must provide static gravity sensitivity. This study resulted in part due to an interest in seeing how the transduction mechanisms of hair cells in a gravity-sensing otolith endorgan would differ from those in the bullfrog sacculus. The bullfrog utriculus is an appropriate model for these studies, because its structure is representative of higher vertebrates in general and its function as a sensor of static gravity and dynamic linear acceleration is well known. Hair cells in the bullfrog utriculus, classifiable as Type 2 by cell body and synapse morphology, differ markedly in hair bundle morphology from those in the bullfrog sacculus. Moreover, the hair bundle morphologies of utricular hair cells, unlike those in the sacculus, differ in different membrane regions.

Kinesins have a dual function in organizing microtubules during both tip growth and cytokinesis in Physcomitrella patens.

PubMed

Hiwatashi, Yuji; Sato, Yoshikatsu; Doonan, John H

2014-03-01

Microtubules (MTs) play a crucial role in the anisotropic deposition of cell wall material, thereby affecting the direction of growth. A wide range of tip-growing cells display highly polarized cell growth, and MTs have been implicated in regulating directionality and expansion. However, the molecular machinery underlying MT dynamics in tip-growing plant cells remains unclear. Here, we show that highly dynamic MT bundles form cyclically in the polarized expansion zone of the moss Physcomitrella patens caulonemal cells through the coalescence of growing MT plus ends. Furthermore, the plant-specific kinesins (KINID1) that are is essential for the proper MT organization at cytokinesis also regulate the turnover of the tip MT bundles as well as the directionality and rate of cell growth. The plus ends of MTs grow toward the expansion zone, and KINID1 is necessary for the stability of a single coherent focus of MTs in the center of the zone, whose formation coincides with the accumulation of KINID1. We propose that KINID-dependent MT bundling is essential for the correct directionality of growth as well as for promoting growth per se. Our findings indicate that two localized cell wall deposition processes, tip growth and cytokinesis, previously believed to be functionally and evolutionarily distinct, share common and plant-specific MT regulatory components.

Vinpocetine Attenuates the Osteoblastic Differentiation of Vascular Smooth Muscle Cells

PubMed Central

Chen, Xiu-Juan; Wang, Na; Yi, Peng-Fei; Song, Min; Zhang, Bo; Wang, Yu-Zhong; Liang, Qiu-Hua

2016-01-01

Vascular calcification is an active process of osteoblastic differentiation of vascular smooth muscle cells; however, its definite mechanism remains unknown. Vinpocetine, a derivative of the alkaloid vincamine, has been demonstrated to inhibit the high glucose-induced proliferation of vascular smooth muscle cells; however, it remains unknown whether vinpocetine can affect the osteoblastic differentiation of vascular smooth muscle cells. We hereby investigated the effect of vinpocetine on vascular calcification using a beta-glycerophosphate-induced cell model. Our results showed that vinpocetine significantly reduced the osteoblast-like phenotypes of vascular smooth muscle cells including ALP activity, osteocalcin, collagen type I, Runx2 and BMP-2 expression as well as the formation of mineralized nodule. Vinpocetine, binding to translocation protein, induced phosphorylation of extracellular signal-related kinase and Akt and thus inhibited the translocation of nuclear factor-kappa B into the nucleus. Silencing of translocator protein significantly attenuated the inhibitory effect of vinpocetine on osteoblastic differentiation of vascular smooth muscle cells. Taken together, vinpocetine may be a promising candidate for the clinical therapy of vascular calcification. PMID:27589055

Imaging extracellular calcium in endolymph

NASA Astrophysics Data System (ADS)

Strimbu, C. Elliott; Fridberger, Anders

2018-05-01

Hair cell mechanoelectrical transduction and adaptation are believed to be regulated by extracellular calcium. However, the majority of experiments addressing calcium's role have been performed on reduced preparations in conditions that do not mimic those present in vivo. We used confocal microscopy and a low affinity (kd ˜11 µM) ratiometric fluorescent indicator to measure the extracellular calcium concentration in scala media in an in vitro preparation of the guinea pig cochlea. Microelectrodes were used to measure the cochlear microphonic potential during acoustic stimulation. The mean calcium concentration is significantly higher in the tectorial membrane (TM) than the surrounding endolymph, suggesting that the membrane acts as a calcium sink. We also observe calcium hot spots along the underside of the TM, near the outer hair cell bundles and near Hensens stripe close to the inner hair cell bundle. This suggests that the local calcium concentration near the hair bundles exceeds 100 µM, significantly higher than the bulk endolymph. These results were corroborated with fluorescence correlation spectroscopy using a second calcium sensitive dye, Oregon Green 488-BAPTA. Following a brief exposure to loud sound, TM calcium drops dramatically and shows recovery on a similar timescale as the microphonic potential. Our results suggest that the extracellular calcium concentration near the hair bundles is much higher than previously believed and may also serve as a partial control parameter for temporary threshold shifts.

Characterisation of myofibroblasts in fibrovascular tissues of primary and recurrent pterygia

PubMed Central

Touhami, A; Di Pascuale, M A; Kawatika, T; Valle, M Del; Rosa, R H; Dubovy, S; Tseng, S C G

2005-01-01

Aims: To determine the presence and origin of myofibroblasts in pterygia. Methods: 86 specimens including head, body, and fibrovascular tissue from 52 primary and 34 recurrent pterygia and five exenterated eyes without pterygia were searched for the origin of myofibroblasts. All tissues were subjected to haematoxylin and eosin staining, immunohistochemistry using antibodies against alpha smooth muscle actin (α-SMA), desmin, vimentin, and caldesmon, and transmission electron microscopy (TEM). The phenotype of fibroblasts subcultured in a serum free medium from pterygium fibrovascular tissues was characterised by the above antibodies. Bundles of dense fibrous tissues were noted in 86% of the fibrovascular tissue specimens evaluated. Cells within these bundles were characterised as myofibroblasts based on positive staining to α-SMA, but negative to desmin and caldesmon, markers for smooth muscle cells. Interestingly, positive α-SMA staining was also found in the periorbital fibroadipose tissue posterior to Tenon’s capsule near the nasal conjunctiva in all exenterated specimens. All first passage fibroblasts expressed vimentin, some were positive to α-SMA, but all were negative to desmin or caldesmon. Cells in pterygium fibrovascular tissues showed ultrastructural features of intracytoplasmic bundles of microfilaments, consistent with myofibroblastic differentiation. Conclusion: These studies collectively demonstrate the presence of contractile myofibroblasts bundle in pterygia and in the periorbital fibroadipose tissue posterior to Tenon’s capsule of exenterated eyes without pterygium. PMID:15722301

WOX4 and WOX14 act downstream of the PXY receptor kinase to regulate plant vascular proliferation independently of any role in vascular organisation.

PubMed

Etchells, J Peter; Provost, Claire M; Mishra, Laxmi; Turner, Simon R

2013-05-01

In plants, the cambium and procambium are meristems from which vascular tissue is derived. In contrast to most plant cells, stem cells within these tissues are thin and extremely long. They are particularly unusual as they divide down their long axis in a highly ordered manner, parallel to the tangential axis of the stem. CLAVATA3-LIKE/ESR-RELATED 41 (CLE41) and PHLOEM INTERCALATED WITH XYLEM (PXY) are a multifunctional ligand-receptor pair that regulate vascular cell division, vascular organisation and xylem differentiation in vascular tissue. A transcription factor gene, WUSCHEL HOMEOBOX RELATED 4 (WOX4) has been shown to act downstream of PXY. Here we show that WOX4 acts redundantly with WOX14 in the regulation of vascular cell division, but that these genes have no function in regulating vascular organisation. Furthermore, we identify an interaction between PXY and the receptor kinase ERECTA (ER) that affects the organisation of the vascular tissue but not the rate of cell division, suggesting that cell division and vascular organisation are genetically separable. Our observations also support a model whereby tissue organisation and cell division are integrated via PXY and ER signalling, which together coordinate development of different cell types that are essential for normal stem formation.

Trafficking of Aminoglycosides Into Endolymph in Vivo

NASA Astrophysics Data System (ADS)

Wang, Qi; Steyger, Peter S.

2009-02-01

In vitro, aminoglycosides increase the stiffness of cochlear hair cell stereocilia, altering bundle motion and transduction kinetics. Aminoglycosides also permeate the mechanosensitive transduction channel and rapidly initiate cytotoxicity in hair cells. If these effects occur in vivo, aminoglycosides would need to enter endolymph. The most direct route for systemically-administered aminoglycosides to enter endolymph is by trafficking from strial capillaries across the stria vascularis. An as-yet-unidentified active transporter is required to translocate aminoglycosides from the intra-strial space into the cytoplasm of marginal cells. Once in marginal cells, aminoglycosides would passively flow down the electrochemical gradient into endolymph. We present data that support a trans-strial trafficking route of aminoglycosides into endolymph, where they can then interfere with the mechanosensitive hair bundles.

Espins are multifunctional actin cytoskeletal regulatory proteins in the microvilli of chemosensory and mechanosensory cells

PubMed Central

Sekerková, Gabriella; Zheng, Lili; Loomis, Patricia A.; Changyaleket, Benjarat; Whitlon, Donna S.; Mugnaini, Enrico; Bartles, James R.

2010-01-01

Espins are associated with the parallel actin bundles of hair cell stereocilia and are the target of mutations that cause deafness and vestibular dysfunction in mice and humans. Here, we report that espins are also concentrated in the microvilli of a number of other sensory cells: vomeronasal organ sensory neurons, solitary chemoreceptor cells, taste cells and Merkel cells. Moreover, we show that hair cells and these other sensory cells contain novel espin isoforms that arise from a different transcriptional start site and differ significantly from other espin isoforms in their complement of ligand-binding activities and their effects on actin polymerization. The novel espin isoforms of sensory cells bundled actin filaments with high affinity in a Ca2+-resistant fashion, bound actin monomer via a WASP homology 2 domain, bound profilin via a single proline-rich peptide, and caused a dramatic elongation of microvillus-type parallel actin bundles in transfected epithelial cells. In addition, the novel espin isoforms of sensory cells differed from other espin isoforms in that they potently inhibited actin polymerization in vitro, did not bind the Src homology 3 domain of the adapter protein insulin receptor substrate p53 and did not bind the acidic, signaling phospholipid phosphatidylinositol 4,5- bisphosphate. Thus, the espins constitute a family of multifunctional actin cytoskeletal regulatory proteins with the potential to differentially influence the organization, dimensions, dynamics and signaling capabilities of the actin filament-rich, microvillus-type specializations that mediate sensory transduction in a variety of mechanosensory and chemosensory cells. PMID:15190118

Evaluation of healing and external tunnel histology of silver-coated peritoneal catheters in rats.

PubMed

Kathuria, P; Moore, H L; Mehrotra, R; Prowant, B F; Khanna, R; Twardowski, Z J

1996-01-01

A previous study showed that silver-coating peritoneal catheters tended to decrease the incidence of early exit-site infections in rats. This study was designed to further evaluate the healing, biocompatability, and external tunnel morphology of standard and silver-coated catheters. Catheters were coated with silver by an ion beam-assisted process. Fourteen male Sprague-Dawley rats underwent implantation of either a standard or silver-coated double-cuff peritoneal catheter. Weekly observation and photographs documented exit-site characteristics. Erythema, exudate, loose fit, and poor hair growth were evidence of an inflamed exit. Overt infection was indicated by the presence of three or more of the following: erythema, purulent exudate, exuberant granulation tissue, loose fit, and poor hair growth. Animals were sacrificed at six weeks, and catheters were removed and processed for histology of the external tunnel. Multiple measurements were taken using a Filar eyepiece, and data were expressed as a mean of several readings. Inflammation, vascularity, and fibrosis were judged semiquantitatively. At the end of six weeks, six of the seven exits of the silver catheters showed excellent healing, while one exit site had signs of excessive inflammation. Four of the exit sites of the standard catheters healed well, two were inflamed, and one was overtly infected. The sinus tract of the standard and silver catheters had similar characteristics: keratinized and nonkeratinized epithelium lined the external part of the sinus tract and merged into granulation tissue. A fibrous sheath was noted in some sinus tracts between the granulation tissue and the cuff. The cuff evoked a foreign body reaction, with fibrosis, multiple giant cells, and vascularization. Poorly healing or infected sinus tracts had highly vascular granulation tissue with overlying exudate. The cuff of these catheters had marked inflammation and scanty giant cells, although collagen bundle thickness was similar to the well-healing catheters. In conclusion, silver-coating potentially enhances healing of the exit sites of peritoneal catheters. Additionally, the similarity of the tunnel histomorphology of standard and silver catheters confirms the favorable biocompatibility of silver.

Auditory Mechanics of the Tectorial Membrane and the Cochlear Spiral

PubMed Central

Gavara, Núria; Manoussaki, Daphne; Chadwick, Richard S.

2012-01-01

Purpose of review This review is timely and relevant since new experimental and theoretical findings suggest that cochlear mechanics from the nanoscale to the macroscale are affected by mechanical properties of the tectorial membrane and the spiral shape. Recent findings Main tectorial membrane themes covered are i) composition and morphology, ii) nanoscale mechanical interactions with the outer hair cell bundle, iii) macroscale longitudinal coupling, iv) fluid interaction with inner hair cell bundles, v) macroscale dynamics and waves. Main cochlear spiral themes are macroscale low-frequency energy focusing and microscale organ of Corti shear gain. Implications Findings from new experimental and theoretical models reveal exquisite sensitivity of cochlear mechanical performance to tectorial membrane structural organization, mechanics, and its positioning with respect to hair bundles. The cochlear spiral geometry is a major determinant of low frequency hearing. Suggestions are made for future research directions. PMID:21785353

Stem cell-derived vascular endothelial cells and their potential application in regenerative medicine

USDA-ARS?s Scientific Manuscript database

Although a 'vascular stem cell' population has not been identified or generated, vascular endothelial and mural cells (smooth muscle cells and pericytes) can be derived from currently known pluripotent stem cell sources, including human embryonic stem cells and induced pluripotent stem cells. We rev...

Redox signaling, Nox5 and vascular remodeling in hypertension.

PubMed

Montezano, Augusto C; Tsiropoulou, Sofia; Dulak-Lis, Maria; Harvey, Adam; Camargo, Livia De Lucca; Touyz, Rhian M

2015-09-01

Extensive data indicate a role for reactive oxygen species (ROS) and redox signaling in vascular damage in hypertension. However, molecular mechanisms underlying these processes remain unclear, but oxidative post-translational modification of vascular proteins is critical. This review discusses how proteins are oxidatively modified and how redox signaling influences vascular smooth muscle cell growth and vascular remodeling in hypertension. We also highlight Nox5 as a novel vascular ROS-generating oxidase. Oxidative stress in hypertension leads to oxidative imbalance that affects vascular cell function through redox signaling. Many Nox isoforms produce ROS in the vascular wall, and recent findings show that Nox5 may be important in humans. ROS regulate signaling by numerous processes including cysteine oxidative post-translational modification such as S-nitrosylation, S-glutathionylation and sulfydration. In vascular smooth muscle cells, this influences cellular responses to oxidative stimuli promoting changes from a contractile to a proliferative phenotype. In hypertension, Nox-induced ROS production is increased, leading to perturbed redox signaling through oxidative modifications of vascular proteins. This influences mitogenic signaling and cell cycle regulation, leading to altered cell growth and vascular remodeling in hypertension.

Multilamellar Structures and Filament Bundles Are Found on the Cell Surface during Bunyavirus Egress

PubMed Central

Sanz-Sánchez, Laura; Risco, Cristina

2013-01-01

Inside cells, viruses build specialized compartments for replication and morphogenesis. We observed that virus release associates with specific structures found on the surface of mammalian cells. Cultured adherent cells were infected with a bunyavirus and processed for oriented sectioning and transmission electron microscopy. Imaging of cell basal regions showed sophisticated multilamellar structures (MLS) and extracellular filament bundles with attached viruses. Correlative light and electron microscopy confirmed that both MLS and filaments proliferated during the maximum egress of new viruses. MLS dimensions and structure were reminiscent of those reported for the nanostructures on gecko fingertips, which are responsible for the extraordinary attachment capacity of these lizards. As infected cells with MLS were more resistant to detachment than control cells, we propose an adhesive function for these structures, which would compensate for the loss of adherence during release of new virus progeny. PMID:23799021

The Mechanical Properties of Hydrated Intermediate Filaments: Insights from Hagfish Slime Threads

PubMed Central

Fudge, Douglas S.; Gardner, Kenn H.; Forsyth, V. Trevor; Riekel, Christian; Gosline, John M.

2003-01-01

Intermediate filaments (IFs) impart mechanical integrity to cells, yet IF mechanics are poorly understood. It is assumed that IFs in cells are as stiff as hard α-keratin, F-actin, and microtubules, but the high bending flexibility of IFs and the low stiffness of soft α-keratins suggest that hydrated IFs may be quite soft. To test this hypothesis, we measured the tensile mechanics of the keratin-like threads from hagfish slime, which are an ideal model for exploring the mechanics of IF bundles and IFs because they consist of tightly packed and aligned IFs. Tensile tests suggest that hydrated IF bundles possess low initial stiffness (Ei = 6.4 MPa) and remarkable elasticity (up to strains of 0.34), which we attribute to soft elastomeric IF protein terminal domains in series with stiffer coiled coils. The high tensile strength (180 MPa) and toughness (130 MJ/m3) of IF bundles support the notion that IFs lend mechanical integrity to cells. Their long-range elasticity suggests that IFs may also allow cells to recover from large deformations. X-ray diffraction and congo-red staining indicate that post-yield deformation leads to an irreversible α→β conformational transition in IFs, which leads to plastic deformation, and may be used by cells as a mechanosensory cue. PMID:12944314

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barber, Laura Jeaneen

The purpose of the L’Innovator is to assemble unique, state-of-the-art IP bundles developed at the national labs that aggregate synergistic technologies in furtherance of the emerging hydrogen and fuel cell market. The first L’Innovator IP bundle consists of Oxygen Reduction Reaction (ORR) Catalyst technology developed at Brookhaven National Laboratory (BNL), combined with Membrane Electrode Assembly (MEA) technology developed at Los Alamos National Laboratory (LANL).

Characterization of the Chicken Ovarian Cancer Model

DTIC Science & Technology

2005-08-01

Typical staining of tumor in an area of stromal hyperplasia . Figure 5. Adenocarcinoma, Ovary, Chicken, Her2/neu. Intense staining of tumor cells in...variable amounts of interstitial fibrovascular tissue and/or smooth muscle bundles, which accounted for their scirrhous nature grossly. 22...Figure 25). Figure 25. Peritoneum, Adenocarcinoma. Interstitial fibrovascular tissue and/or smooth muscle bundles account for the scirrhous

The chromokinesin Kid is required for maintenance of proper metaphase spindle size.

PubMed

Tokai-Nishizumi, Noriko; Ohsugi, Miho; Suzuki, Emiko; Yamamoto, Tadashi

2005-11-01

The human chromokinesin Kid/kinesin-10, a plus end-directed microtubule (MT)-based motor with both microtubule- and DNA-binding domains, is required for proper chromosome alignment at the metaphase plate. Here, we performed RNA interference experiments to deplete endogenous Kid from HeLa cells and confirmed defects in metaphase chromosome arm alignment in Kid-depleted cells. In addition, we noted a shortening of the spindle length, resulting in a pole-to-pole distance only 80% of wild type. The spindle microtubule-bundles with which Kid normally colocalize became less robust. Rescue of the two Kid deficiency phenotypes-imprecise chromosome alignment at metaphase and shortened spindles- exhibited distinct requirements. Mutants lacking either the DNA-binding domain or the MT motor ATPase failed to rescue the former defect, whereas rescue of the shortened spindle phenotype required neither activity. Kid also exhibits microtubule bundling activity in vitro, and rescue of the shortened spindle phenotype and the bundling activity displayed similar domain requirements, except that rescue required a coiled-coil domain not needed for bundling. These results suggest that distinct from its role in chromosome movement, Kid contributes to spindle morphogenesis by mediating spindle microtubules stabilization.

The Chromokinesin Kid Is Required for Maintenance of Proper Metaphase Spindle SizeD⃞

PubMed Central

Tokai-Nishizumi, Noriko; Ohsugi, Miho; Suzuki, Emiko; Yamamoto, Tadashi

2005-01-01

The human chromokinesin Kid/kinesin-10, a plus end-directed microtubule (MT)-based motor with both microtubule- and DNA-binding domains, is required for proper chromosome alignment at the metaphase plate. Here, we performed RNA interference experiments to deplete endogenous Kid from HeLa cells and confirmed defects in metaphase chromosome arm alignment in Kid-depleted cells. In addition, we noted a shortening of the spindle length, resulting in a pole-to-pole distance only 80% of wild type. The spindle microtubule-bundles with which Kid normally colocalize became less robust. Rescue of the two Kid deficiency phenotypes—imprecise chromosome alignment at metaphase and shortened spindles— exhibited distinct requirements. Mutants lacking either the DNA-binding domain or the MT motor ATPase failed to rescue the former defect, whereas rescue of the shortened spindle phenotype required neither activity. Kid also exhibits microtubule bundling activity in vitro, and rescue of the shortened spindle phenotype and the bundling activity displayed similar domain requirements, except that rescue required a coiled-coil domain not needed for bundling. These results suggest that distinct from its role in chromosome movement, Kid contributes to spindle morphogenesis by mediating spindle microtubules stabilization. PMID:16176979

Rheological alteration of erythrocytes exposed to carbon nanotubes.

PubMed

Heo, Yujin; Li, Cheng-Ai; Kim, Duckjong; Shin, Sehyun

2017-01-01

Single-walled carbon nanotubes (SWNTs) have been increasingly used in a variety of biomedical applications, such as in vivo delivery of drugs and tumor imaging. Potential exposure of SWNTs to human red blood cells (RBCs) may cause serious toxicity including alteration of mechanical properties of cells. The present study investigated the cellular response to exposure of SWNTs with measuring rheological characteristics of RBCs, including hemolysis, deformability, aggregation, and morphological changes. RBCs were exposed to two different dispersion-state samples (i.e. individual SWNTs and bundled SWNTs) in chitosan hydroxyphenyl acetamide (CHPA) solutions. The concentrations of SWNTs were carefully chosen to avoid any hemorheological alterations due to hemolysis. Rheological characteristics were measured using microfluidic-laser diffractometry and aggregometry. Our results show that the bundled SWNTs had higher hemolytic activity than did the individual SWNTs. RBC aggregation apparently decreased as the concentration of SWNTs or incubation time increased. Additionally, bundled SWNTs caused significant alterations in the shape and fusion of RBCs. In conclusion, bundled SWNTs were found to be more toxic than individual SWNTs. These results provide important insights into the interactions between RBCs and SWNTs and will facilitate assessment of the risk of nanomaterial toxicity of blood.

[Clinicopathological study of primary meningeal hemangiopericytoma].

PubMed

Shi, Qun-li; Chen, Xu-dong; Lu, Zhen-feng; Meng, Kui; Jin, Xing-zao; Yan, Xiao-wen; Zhou, Xiao-jun; Sheng, Chun-ning

2002-10-01

Meningeal hemangiopericytoma is an uncommon tumor. This study was designed to investigate the clinicopathological and biology behavior of primary meningeal hemangiopericytoma. Clinical data, combined with histopathology and immunohistochemistry of 20 cases of meningeal hemangiopericytoma were reviewed, in which 4 specimens were examined with electron microscope. The average age of patients with primary meningeal hemangiopericytoma was 42.4 year-old (21-69 years). The ratio of male to female was 1.2: 1. Most of the patients went to hospital for the symptoms of central nervous system such as headache. The tumor could occur on any locus of the cranial or spinal dura. Grossly, many of the tumors had capsule, whose testure were tenacious, and part of them looks like fish meat. Histopathologically, the small vascular spaces in the tumor were rich, the typical antler-liked vessel could be found, the short-spindle tumor cells were around the vessel, and distributed by radiation-shape. The tumor cells were pleomorphic and atypical, and could be found mitotic activity. Staining of argyrophilic fiber: the argyrophilic fiber surrounded single tumor cell, and distributed by radiation-shape around vessel. Immunohistochemistry showed negative for S-100 protein, F VIII, EMA, GFAP and CD34, while Vim was positive. Electron microscopically, the rich bundles of 10nm long intermediate filaments could be found in tumor cells. The exobasallamina, of cells were evidenced, and distributed around single cell. Follow-up, 8 of 17 cases were relapsed (47.1%). Meningeal hemangiopericytoma is a low-malignant tumor original from meningeal mesenchymal tissue. The features of histopathology, immunphenotype and ultrastructure are similar to hemangiopericytoma of the soft tissue.

A Dicarboxylate Transporter, LjALMT4, Mainly Expressed in Nodules of Lotus japonicus.

PubMed

Takanashi, Kojiro; Sasaki, Takayuki; Kan, Tomohiro; Saida, Yuka; Sugiyama, Akifumi; Yamamoto, Yoko; Yazaki, Kazufumi

2016-07-01

Legume plants can establish symbiosis with soil bacteria called rhizobia to obtain nitrogen as a nutrient directly from atmospheric N2 via symbiotic nitrogen fixation. Legumes and rhizobia form nodules, symbiotic organs in which fixed-nitrogen and photosynthetic products are exchanged between rhizobia and plant cells. The photosynthetic products supplied to rhizobia are thought to be dicarboxylates but little is known about the movement of dicarboxylates in the nodules. In terms of dicarboxylate transporters, an aluminum-activated malate transporter (ALMT) family is a strong candidate responsible for the membrane transport of carboxylates in nodules. Among the seven ALMT genes in the Lotus japonicus genome, only one, LjALMT4, shows a high expression in the nodules. LjALMT4 showed transport activity in a Xenopus oocyte system, with LjALMT4 mediating the efflux of dicarboxylates including malate, succinate, and fumarate, but not tricarboxylates such as citrate. LjALMT4 also mediated the influx of several inorganic anions. Organ-specific gene expression analysis showed LjALMT4 mRNA mainly in the parenchyma cells of nodule vascular bundles. These results suggest that LjALMT4 may not be involved in the direct supply of dicarboxylates to rhizobia in infected cells but is responsible for supplying malate as well as several anions necessary for symbiotic nitrogen fixation, via nodule vasculatures.

Map-based Cloning and Characterization of the BPH18 Gene from Wild Rice Conferring Resistance to Brown Planthopper (BPH) Insect Pest

PubMed Central

Ji, Hyeonso; Kim, Sung-Ryul; Kim, Yul-Ho; Suh, Jung-Pil; Park, Hyang-Mi; Sreenivasulu, Nese; Misra, Gopal; Kim, Suk-Man; Hechanova, Sherry Lou; Kim, Hakbum; Lee, Gang-Seob; Yoon, Ung-Han; Kim, Tae-Ho; Lim, Hyemin; Suh, Suk-Chul; Yang, Jungil; An, Gynheung; Jena, Kshirod K.

2016-01-01

Brown planthopper (BPH) is a phloem sap-sucking insect pest of rice which causes severe yield loss. We cloned the BPH18 gene from the BPH-resistant introgression line derived from the wild rice species Oryza australiensis. Map-based cloning and complementation test revealed that the BPH18 encodes CC-NBS-NBS-LRR protein. BPH18 has two NBS domains, unlike the typical NBS-LRR proteins. The BPH18 promoter::GUS transgenic plants exhibited strong GUS expression in the vascular bundles of the leaf sheath, especially in phloem cells where the BPH attacks. The BPH18 proteins were widely localized to the endo-membranes in a cell, including the endoplasmic reticulum, Golgi apparatus, trans-Golgi network, and prevacuolar compartments, suggesting that BPH18 may recognize the BPH invasion at endo-membranes in phloem cells. Whole genome sequencing of the near-isogenic lines (NILs), NIL-BPH18 and NIL-BPH26, revealed that BPH18 located at the same locus of BPH26. However, these two genes have remarkable sequence differences and the independent NILs showed differential BPH resistance with different expression patterns of plant defense-related genes, indicating that BPH18 and BPH26 are functionally different alleles. These findings would facilitate elucidation of the molecular mechanism of BPH resistance and the identified novel alleles to fast track breeding BPH resistant rice cultivars. PMID:27682162

Map-based Cloning and Characterization of the BPH18 Gene from Wild Rice Conferring Resistance to Brown Planthopper (BPH) Insect Pest.

PubMed

Ji, Hyeonso; Kim, Sung-Ryul; Kim, Yul-Ho; Suh, Jung-Pil; Park, Hyang-Mi; Sreenivasulu, Nese; Misra, Gopal; Kim, Suk-Man; Hechanova, Sherry Lou; Kim, Hakbum; Lee, Gang-Seob; Yoon, Ung-Han; Kim, Tae-Ho; Lim, Hyemin; Suh, Suk-Chul; Yang, Jungil; An, Gynheung; Jena, Kshirod K

2016-09-29

Brown planthopper (BPH) is a phloem sap-sucking insect pest of rice which causes severe yield loss. We cloned the BPH18 gene from the BPH-resistant introgression line derived from the wild rice species Oryza australiensis. Map-based cloning and complementation test revealed that the BPH18 encodes CC-NBS-NBS-LRR protein. BPH18 has two NBS domains, unlike the typical NBS-LRR proteins. The BPH18 promoter::GUS transgenic plants exhibited strong GUS expression in the vascular bundles of the leaf sheath, especially in phloem cells where the BPH attacks. The BPH18 proteins were widely localized to the endo-membranes in a cell, including the endoplasmic reticulum, Golgi apparatus, trans-Golgi network, and prevacuolar compartments, suggesting that BPH18 may recognize the BPH invasion at endo-membranes in phloem cells. Whole genome sequencing of the near-isogenic lines (NILs), NIL-BPH18 and NIL-BPH26, revealed that BPH18 located at the same locus of BPH26. However, these two genes have remarkable sequence differences and the independent NILs showed differential BPH resistance with different expression patterns of plant defense-related genes, indicating that BPH18 and BPH26 are functionally different alleles. These findings would facilitate elucidation of the molecular mechanism of BPH resistance and the identified novel alleles to fast track breeding BPH resistant rice cultivars.

Laser speckle contrast imaging: monitoring blood flow dynamics and vascular structure of photodynamic therapy

NASA Astrophysics Data System (ADS)

Liu, Qian; Zhou, Sibo; Zhang, Zhihong; Luo, Qingming

2005-01-01

Laser speckle contrast imaging (LSCI) is a noninvasive optical image technique that has been developed for imaging in vivo blood flow dynamics and vascular structure with high spatial and temporal resolution. It records the full-field spatio-temporal characteristics of microcirculation in real time without the need of laser beam flying. In this paper applications of this technique for monitoring changes of blood flow and vascular structure following photodynamic therapy (PDT) in vivo model were demonstrated. In this study, an in vivo model of chick chorioallantoic membrane (CAM) at embryo age (EA) of 10~13 days, was observed following PDT irradiated by a power tunable laser diode (λ = 656.5 nm). Laser intensity incident on the treatment site was maintained at 40 mW/cm2 and photosensitizer of Pyropheophorbide Acid (Pyro-Acid) was used. CAM was adopted in PDT since it is a transparent in vivo model and the irradiated lights of laser can penetrate tumor with greater depth. The laser delivered through fiber bundle to the treatment site in PDT also acted as the coherent light source of LSCI. This study shows that LSCI can be used to assess the efficacy of peripheral vessels damage of tumor in PDT by monitoring changes of blood flow and vascular structure.

Patient-specific cardiovascular progenitor cells derived from integration-free induced pluripotent stem cells for vascular tissue regeneration.

PubMed

Hu, Jiang; Wang, Yongyu; Jiao, Jiao; Liu, Zhongning; Zhao, Chao; Zhou, Zhou; Zhang, Zhanpeng; Forde, Kaitlynn; Wang, Lunchang; Wang, Jiangang; Baylink, David J; Zhang, Xiao-Bing; Gao, Shaorong; Yang, Bo; Chen, Y Eugene; Ma, Peter X

2015-12-01

Tissue-engineered blood vessels (TEBVs) are promising in regenerating a live vascular replacement. However, the vascular cell source is limited, and it is crucial to develop a scaffold that accommodates new type of vascular progenitor cells and facilitates in vivo lineage specification of the cells into functional vascular smooth muscle cells (VSMCs) to regenerate vascular tissue. In the present study, integration-free human induced pluripotent stem cells (hiPSCs) were established from patient peripheral blood mononuclear cells through episomal vector nucleofection of reprogramming factors. The established hiPSCs were then induced into mesoderm-originated cardiovascular progenitor cells (CVPCs) with a highly efficient directed lineage specification method. The derived CVPCs were demonstrated to be able to differentiate into functional VSMCs. Subcutaneous implantation of CVPCs seeded on macroporous nanofibrous poly(l-lactide) scaffolds led to in vivo VSMC lineage specification and matrix deposition inside the scaffolds. In summary, we established integration-free patient-specific hiPSCs from peripheral blood mononuclear cells, derived CVPCs through directed lineage specification, and developed an advanced scaffold for these progenitor cells to further differentiate in vivo into VSMCs and regenerate vascular tissue in a subcutaneous implantation model. This study has established an efficient patient-specific approach towards in vivo regeneration of vascular tissue. Copyright © 2015 Elsevier Ltd. All rights reserved.

Thick Filament Length and Isoform Composition Determine Self-Organized Contractile Units in Actomyosin Bundles

PubMed Central

Thoresen, Todd; Lenz, Martin; Gardel, Margaret L.

2013-01-01

Diverse myosin II isoforms regulate contractility of actomyosin bundles in disparate physiological processes by variations in both motor mechanochemistry and the extent to which motors are clustered into thick filaments. Although the role of mechanochemistry is well appreciated, the extent to which thick filament length regulates actomyosin contractility is unknown. Here, we study the contractility of minimal actomyosin bundles formed in vitro by mixtures of F-actin and thick filaments of nonmuscle, smooth, and skeletal muscle myosin isoforms with varied length. Diverse myosin II isoforms guide the self-organization of distinct contractile units within in vitro bundles with shortening rates similar to those of in vivo myofibrils and stress fibers. The tendency to form contractile units increases with the thick filament length, resulting in a bundle shortening rate proportional to the length of constituent myosin thick filament. We develop a model that describes our data, providing a framework in which to understand how diverse myosin II isoforms regulate the contractile behaviors of disordered actomyosin bundles found in muscle and nonmuscle cells. These experiments provide insight into physiological processes that use dynamic regulation of thick filament length, such as smooth muscle contraction. PMID:23442916

Xyloside primed glycosaminoglycans alter hair bundle micromechanical coupling and synaptic transmission: Pharmacokinetics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holman, Holly A.; Nguyen, Lynn Y.; Tran, Vy M.

Glycosaminoglycans (GAGs) are ubiquitous in the inner ear, and disorders altering their structure or production often result in debilitating hearing and balance deficits. The specific mechanisms responsible for loss of hair-cell function are not well understood. We recently reported that introduction of a novel BODIPY conjugated xyloside (BX) into the endolymph primes fluorescent GAGs in vivo [6, 15]. Confocal and two-photon fluorescence imaging revealed rapid turnover and assembly of a glycocalyx enveloping the kinocilia and extending into the cupula, a structure that presumably serves as a mechanical link between the hair bundle and the cupula. Extracellular fluorescence was also observedmore » around the basolateral surface of hair cells and surrounding afferent nerve projections into the crista. Single unit afferent recordings during mechanical hair bundle stimulation revealed temporary interruption of synaptic transmission following BX administration followed by recovery, demonstrating an essential role for GAGs in function of the hair cell synapse. In the present work we present a pharmacokinetic model to quantify the time course of BX primed GAG production and turnover in the ear.« less

Xyloside primed glycosaminoglycans alter hair bundle micromechanical coupling and synaptic transmission: Pharmacokinetics

NASA Astrophysics Data System (ADS)

Holman, Holly A.; Tran, Vy M.; Nguyen, Lynn Y.; Arungundram, Sailaja; Kalita, Mausam; Kuberan, Balagurunathan; Rabbitt, Richard D.

2015-12-01

Glycosaminoglycans (GAGs) are ubiquitous in the inner ear, and disorders altering their structure or production often result in debilitating hearing and balance deficits. The specific mechanisms responsible for loss of hair-cell function are not well understood. We recently reported that introduction of a novel BODIPY conjugated xyloside (BX) into the endolymph primes fluorescent GAGs in vivo [6, 15]. Confocal and two-photon fluorescence imaging revealed rapid turnover and assembly of a glycocalyx enveloping the kinocilia and extending into the cupula, a structure that presumably serves as a mechanical link between the hair bundle and the cupula. Extracellular fluorescence was also observed around the basolateral surface of hair cells and surrounding afferent nerve projections into the crista. Single unit afferent recordings during mechanical hair bundle stimulation revealed temporary interruption of synaptic transmission following BX administration followed by recovery, demonstrating an essential role for GAGs in function of the hair cell synapse. In the present work we present a pharmacokinetic model to quantify the time course of BX primed GAG production and turnover in the ear.

A Polypyrimidine Tract Binding Protein, Pumpkin RBP50, Forms the Basis of a Phloem-Mobile Ribonucleoprotein Complex[W

PubMed Central

Ham, Byung-Kook; Brandom, Jeri L.; Xoconostle-Cázares, Beatriz; Ringgold, Vanessa; Lough, Tony J.; Lucas, William J.

2009-01-01

RNA binding proteins (RBPs) are integral components of ribonucleoprotein (RNP) complexes and play a central role in RNA processing. In plants, some RBPs function in a non-cell-autonomous manner. The angiosperm phloem translocation stream contains a unique population of RBPs, but little is known regarding the nature of the proteins and mRNA species that constitute phloem-mobile RNP complexes. Here, we identified and characterized a 50-kD pumpkin (Cucurbita maxima cv Big Max) phloem RNA binding protein (RBP50) that is evolutionarily related to animal polypyrimidine tract binding proteins. In situ hybridization studies indicated a high level of RBP50 transcripts in companion cells, while immunolocalization experiments detected RBP50 in both companion cells and sieve elements. A comparison of the levels of RBP50 present in vascular bundles and phloem sap indicated that this protein is highly enriched in the phloem sap. Heterografting experiments confirmed that RBP50 is translocated from source to sink tissues. Collectively, these findings established that RBP50 functions as a non-cell-autonomous RBP. Protein overlay, coimmunoprecipitation, and cross-linking experiments identified the phloem proteins and mRNA species that constitute RBP50-based RNP complexes. Gel mobility-shift assays demonstrated that specificity, with respect to the bound mRNA, is established by the polypyrimidine tract binding motifs within such transcripts. We present a model for RBP50-based RNP complexes within the pumpkin phloem translocation stream. PMID:19122103

HMGB1 Promotes Intraoral Palatal Wound Healing through RAGE-Dependent Mechanisms

PubMed Central

Tancharoen, Salunya; Gando, Satoshi; Binita, Shrestha; Nagasato, Tomoka; Kikuchi, Kiyoshi; Nawa, Yuko; Dararat, Pornpen; Yamamoto, Mika; Narkpinit, Somphong; Maruyama, Ikuro

2016-01-01

High mobility group box 1 (HMGB1) is tightly connected to the process of tissue organization upon tissue injury. Here we show that HMGB1 controls epithelium and connective tissue regeneration both in vivo and in vitro during palatal wound healing. Heterozygous HMGB1 (Hmgb1+/−) mice and Wild-type (WT) mice were subjected to palatal injury. Maxillary tissues were stained with Mallory Azan or immunostained with anti-HMGB1, anti-proliferating cell nuclear antigen (PCNA), anti-nuclear factor-κB (NF-κB) p50 and anti-vascular endothelial growth factor (VEGF) antibodies. Palatal gingival explants were cultured with recombinant HMGB1 (rHMGB1) co-treated with siRNA targeting receptor for advanced glycation end products (RAGEs) for cell migration and PCNA expression analysis. Measurement of the wound area showed differences between Hmgb1+/− and WT mice on Day 3 after wounding. Mallory Azan staining showed densely packed of collagen fibers in WT mice, whereas in Hmgb1+/− mice weave-like pattern of low density collagen bundles were present. At three and seven days post-surgery, PCNA, NF-κB p50 and VEGF positive keratinocytes of WT mice were greater than that of Hmgb1+/− mice. Knockdown of RAGE prevents the effect of rHMGB1-induced cell migration and PCNA expression in gingival cell cultures. The data suggest that HMGB1/RAGE axis has crucial roles in palatal wound healing. PMID:27886093

Tracking multi-walled carbon nanotubes inside oat (Avena sativa L.) plants and assessing their effect on growth, yield, and mammalian (human) cell viability

NASA Astrophysics Data System (ADS)

Joshi, Anjali; Kaur, Simranjeet; Singh, Pargat; Dharamvir, Keya; Nayyar, Harsh; Verma, Gaurav

2018-05-01

Our findings show that oxidized multi-walled carbon nanotubes (MWCNT) having serpent-like morphology and smaller sizes (diameter of 35 nm and lengths of 200-300 nm) are compatible with oat plant tissues. Applied by seed-priming method as 90 µg/ml concentration, these serpentine MWCNT (having open-end caps) enter the oat plant and traverse the cells. Tracking of MWCNT inside sections and tissues during growth of oat plant has been done using special sample preparation. We present clear images of MWCNT inside the primed seeds and vascular bundles, the conducting tissues of root and shoot of oat. A dye fluorescein isothiocyanate non-covalently bonded to MWCNT also helped in detecting the path through circumferential perimeters of the oat channels, using fluorescence and confocal microscopy. The presence of MWCNT inside oat enhanced the growth of xylem cells by about 1.85-fold in vasculature of shoots. Compared to controls, the chlorophyll content increased by 57%, while photosynthetic activity enhanced by 15% for the same sample in MWCNT-primed plants. Overall, the growth factors were also augmented leading to significant increase in yield components. No toxic effects of MWCNT were observed in the DNA of the primed plants, and in the human cell lines treated with grains harvested from the MWCNT-primed plants. Our study provides some new insights about the role of MWCNT in plants and their potential benefits in agriculture.

ELIGULUM-A Regulates Lateral Branch and Leaf Development in Barley1[OPEN

PubMed Central

Haaning, Allison; Bilgic, Hatice

2018-01-01

The shoot apical and axillary meristems control shoot development, effectively influencing lateral branch and leaf formation. The barley (Hordeum vulgare) uniculm2 (cul2) mutation blocks axillary meristem development, and mutant plants lack lateral branches (tillers) that normally develop from the crown. A genetic screen for cul2 suppressors recovered two recessive alleles of ELIGULUM-A (ELI-A) that partially rescued the cul2 tillering phenotype. Mutations in ELI-A produce shorter plants with fewer tillers and disrupt the leaf blade-sheath boundary, producing liguleless leaves and reduced secondary cell wall development in stems and leaves. ELI-A is predicted to encode an unannotated protein containing an RNaseH-like domain that is conserved in land plants. ELI-A transcripts accumulate at the preligule boundary, the developing ligule, leaf margins, cells destined to develop secondary cell walls, and cells surrounding leaf vascular bundles. Recent studies have identified regulatory similarities between boundary development in leaves and lateral organs. Interestingly, we observed ELI-A transcripts at the preligule boundary, suggesting that ELI-A contributes to boundary formation between the blade and sheath. However, we did not observe ELI-A transcripts at the axillary meristem boundary in leaf axils, suggesting that ELI-A is not involved in boundary development for axillary meristem development. Our results show that ELI-A contributes to leaf and lateral branch development by acting as a boundary gene during ligule development but not during lateral branch development. PMID:29440592

An Epichloë festucae homologue of MOB3, a component of the STRIPAK complex, is required for the establishment of a mutualistic symbiotic interaction with Lolium perenne

PubMed Central

Green, Kimberly A.; Becker, Yvonne; Fitzsimons, Helen L.

2016-01-01

Summary In both Sordaria macrospora and Neurospora crassa, components of the conserved STRIPAK (striatin‐interacting phosphatase and kinase) complex regulate cell–cell fusion, hyphal network development and fruiting body formation. Interestingly, a number of Epichloë festucae genes that are required for hyphal cell–cell fusion, such as noxA, noxR, proA, mpkA and mkkA, are also required for the establishment of a mutualistic symbiotic interaction with Lolium perenne. To determine whether MobC, a homologue of the STRIPAK complex component MOB3 in S. macrospora and N. crassa, is required for E. festucae hyphal fusion and symbiosis, a mobC deletion strain was generated. The ΔmobC mutant showed reduced rates of hyphal cell–cell fusion, formed intrahyphal hyphae and exhibited enhanced conidiation. Plants infected with ΔmobC were severely stunted. Hyphae of ΔmobC showed a proliferative pattern of growth within the leaves of Lolium perenne with increased colonization of the intercellular spaces and vascular bundles. Although hyphae were still able to form expressoria, structures allowing the colonization of the leaf surface, the frequency of formation was significantly reduced. Collectively, these results show that the STRIPAK component MobC is required for the establishment of a mutualistic symbiotic association between E. festucae and L. perenne, and plays an accessory role in the regulation of hyphal cell–cell fusion and expressorium development in E. festucae. PMID:27277141

Stem cell function during plant vascular development

PubMed Central

Miyashima, Shunsuke; Sebastian, Jose; Lee, Ji-Young; Helariutta, Yka

2013-01-01

The plant vascular system, composed of xylem and phloem, evolved to connect plant organs and transport various molecules between them. During the post-embryonic growth, these conductive tissues constitutively form from cells that are derived from a lateral meristem, commonly called procambium and cambium. Procambium/cambium contains pluripotent stem cells and provides a microenvironment that maintains the stem cell population. Because vascular plants continue to form new tissues and organs throughout their life cycle, the formation and maintenance of stem cells are crucial for plant growth and development. In this decade, there has been considerable progress in understanding the molecular control of the organization and maintenance of stem cells in vascular plants. Noticeable advance has been made in elucidating the role of transcription factors and major plant hormones in stem cell maintenance and vascular tissue differentiation. These studies suggest the shared regulatory mechanisms among various types of plant stem cell pools. In this review, we focus on two aspects of stem cell function in the vascular cambium, cell proliferation and cell differentiation. PMID:23169537

Pathophysiological consequences of VEGF-induced vascular permeability

NASA Astrophysics Data System (ADS)

Weis, Sara M.; Cheresh, David A.

2005-09-01

Although vascular endothelial growth factor (VEGF) induces angiogenesis, it also disrupts vascular barrier function in diseased tissues. Accordingly, VEGF expression in cancer and ischaemic disease has unexpected pathophysiological consequences. By uncoupling endothelial cell-cell junctions VEGF causes vascular permeability and oedema, resulting in extensive injury to ischaemic tissues after stroke or myocardial infarction. In cancer, VEGF-mediated disruption of the vascular barrier may potentiate tumour cell extravasation, leading to widespread metastatic disease. Therefore, by blocking the vascular permeability promoting effects of VEGF it may be feasible to reduce tissue injury after ischaemic disease and minimize the invasive properties of circulating tumour cells.

Hematopoietic stem cell capture and directional differentiation into vascular endothelial cells for metal stent-coated chitosan/hyaluronic acid loading CD133 antibody.

PubMed

Zhang, Shixuan; Zhang, Fan; Feng, Bo; Fan, Qingyu; Yang, Feng; Shang, Debin; Sui, Jinghan; Zhao, Hong

2015-03-01

A series of metal stents coated with chitosan/hyaluronic acid (CS/HA) loading antibodies by electrostatic self-assembled method were prepared, and the types of cells captured by antibodies and their differentiation in vascular endothelial cells (ECs) evaluated by molecular biology and scanning electron microscope. The results showed that CD133 stent can selectively capture hematopoietic stem cells (HSC),which directionally differentiate into vascular ECs in peripheral blood by (CS/HA) induction, and simultaneously inhibit migration and proliferation of immune cells and vascular smooth muscle cells (MCs). CD34 stent can capture HSC, hematopoietic progenitor cells that differentiate into vascular ECs and immune cells, promoting smooth MCs growth, leading to thrombosis, inflammation, and rejection. CD133 stent can be implanted into miniature pig heart coronary and can repair vascular damage by capturing own HSC, thus contributing to the rapid natural vascular repair, avoiding inflammation and rejection, thrombosis and restenosis. These studies demonstrated that CD133 stent of HSC capture will be an ideal coated metal stent providing a new therapeutic approach for cardiovascular and cerebrovascular disease.

Nitrogen fertilizer application affects lodging resistance by altering secondary cell wall synthesis in japonica rice (Oryza sativa).

PubMed

Zhang, Wujun; Wu, Longmei; Ding, Yanfeng; Yao, Xiong; Wu, Xiaoran; Weng, Fei; Li, Ganghua; Liu, Zhenghui; Tang, She; Ding, Chengqiang; Wang, Shaohua

2017-09-01

Stem mechanical strength is an important agricultural quantitative trait that is closely related to lodging resistance in rice, which is known to be reduced by fertilizer with higher levels of nitrogen. To understand the mechanism that regulates stem mechanical strength in response to nitrogen, we analysed stem morphology, anatomy, mechanical properties, cell wall components, and expression of cell wall-related genes, in two varieties of japonica rice, namely, Wuyunjing23 (lodging-resistant variety) and W3668 (lodging-susceptible variety). The results showed that higher nitrogen fertilizer increased the lodging index in both varieties due to a reduction in breaking strength and bending stress, and these changes were larger in W3668. Cellulose content decreased slightly under higher nitrogen fertilizer, whereas lignin content reduced remarkably. Histochemical staining revealed that high nitrogen application decreased lignin deposition in the secondary cell wall of the sclerenchyma cells and vascular bundle cells compared with the low nitrogen treatments, while it did not alter the pattern of cellulose deposition in these cells in both Wuyunjing23 and W3668. In addition, the expression of the genes involved in lignin biosynthesis, OsPAL, OsCoMT, Os4CL3, OsCCR, OsCAD2, OsCAD7, OsCesA4, and OsCesA7, were also down-regulated under higher nitrogen conditions at the early stage of culm growth. These results suggest that the genes involved in lignin biosynthesis are down-regulated by higher nitrogen fertilizer, which causes lignin deficiency in the secondary cell walls and the weakening of mechanical tissue structure. Subsequently, this results in these internodes with reduced mechanical strength and poor lodging resistance.

Localization of nitric oxide synthase and NADPH-diaphorase in guinea pig and human cochleae.

PubMed

Ruan, R S; Leong, S K; Yeoh, K H

1997-01-01

The distributions of nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) and nitric oxide synthase (NOS) in mammalian cochlea were studied at light and electron microscope levels by NADPH-d histochemistry and brain NOS (bNOS) immunohistochemistry. The cochleae from 15 albino guinea pigs were perilymphatically fixed with 2% periodate-lysine-paraformaldehyde, decalcified in 10% EDTA and processed for light and electron microscopy after NADPH-d or NOS staining in frozen and vibratome sections respectively. One human cochlea was available for light microscope examination of NADPH-d or bNOS stained sections. Light microscope results revealed that type I neurons and nerve fibers of the spiral ganglion cells were labeled by bNOS immunohistochemistry as well as NADPH-d histochemistry in both guinea pig and human cochleae. At subcellular level, NADPH-d reaction product was localized in the mitochondria of the neuronal cytoplasm and axoplasm and in the cytoplasm of the vascular endothelium. The immunoreaction products of bNOS were evenly distributed in the neuronal cytoplasm and axoplasm. Myelinated and unmyelinated fibers in the intraganglionic spiral bundle and the inner spiral and inner radial fibers below the inner hair cells were labeled for bNOS. The nerve endings below the outer hair cells were not stained. NOS immunoreaction product was also found in the outer hair cells, Schwann cells of myelinated nerve fibers, Deiter's cells, pillar cells and the tympanic lamina cells. No difference was found in the staining pattern of both NADPH-d and NOS reaction products between human and guinea pig cochleae at the light microscope level. The results suggest that NO plays an important role in the maintenance of auditory function in the mammal.

Repair of traumatized mammalian hair cells via sea anemone repair proteins.

PubMed

Tang, Pei-Ciao; Smith, Karen Müller; Watson, Glen M

2016-08-01

Mammalian hair cells possess only a limited ability to repair damage after trauma. In contrast, sea anemones show a marked capability to repair damaged hair bundles by means of secreted repair proteins (RPs). Previously, it was found that recovery of traumatized hair cells in blind cavefish was enhanced by anemone-derived RPs; therefore, the ability of anemone RPs to assist recovery of damaged hair cells in mammals was tested here. After a 1 h incubation in RP-enriched culture media, uptake of FM1-43 by experimentally traumatized murine cochlear hair cells was restored to levels comparable to those exhibited by healthy controls. In addition, RP-treated explants had significantly more normally structured hair bundles than time-matched traumatized control explants. Collectively, these results indicate that anemone-derived RPs assist in restoring normal function and structure of experimentally traumatized hair cells of the mouse cochlea. © 2016. Published by The Company of Biologists Ltd.

In-Depth Analysis of the Structure and Properties of Two Varieties of Natural Luffa Sponge Fibers

PubMed Central

Chen, Yuxia; Su, Na; Zhang, Kaiting; Zhu, Shiliu; Zhao, Lei; Fang, Fei; Ren, Linyan; Guo, Yong

2017-01-01

The advancement in science and technology has led to luffa sponge (LS) being widely used as a natural material in industrial application because of its polyporous structure and light texture. To enhance the utility of LS fibers as the reinforcement of lightweight composite materials, the current study investigates their water absorption, mechanical properties, anatomical characteristics and thermal performance. Hence, moisture regain and tensile properties of LS fiber bundles were measured in accordance with American Society for Testing and Materials (ASTM) standards while their structural characteristics were investigated via microscopic observation. Scanning electron microscopy (SEM) was used to observe the surface morphology and fractured surface of fiber bundles. The test results show that the special structure where the phloem tissues degenerate to cavities had a significant influence on the mechanical properties of LS fiber bundles. Additionally, the transverse sectional area occupied by fibers in a fiber bundle (SF), wall thickness, ratio of wall to lumen of fiber cell, and crystallinity of cellulose had substantial impact on the mechanical properties of LS fiber bundles. Furthermore, the density of fiber bundles of LS ranged within 385.46–468.70 kg/m3, significantly less than that of jute (1360.40 kg/m3) and Arenga engleri (950.20 kg/m3). However, LS fiber bundles demonstrated superior specific modulus than Arenga engleri. PMID:28772838

Targeting Phosphatidylserine for Radioimmunotherapy of Breast Cancer Brain Metastasis

DTIC Science & Technology

2015-12-01

response. e. Correlate imaging findings with histological studies of vascular damage, tumor cell and endothelial cell apoptosis or necrosis and vascular ...phosphatidylserine (PS) is exposed exclusively on tumor vascular endothelium of brain metastases in mouse models. A novel PS-targeting antibody, PGN635... vascular endothelial cells in multi-focal brain metastases throughout the whole mouse brain. Vascular endothelium in normal brain tissues is negative

Distinguishing the Chinese materia medica Tiepishihu from similar Dendrobium species of the same genus using histological and microscopic method.

PubMed

Yu, Kun-Zi; Yan, Hua; Tai, Hai-Chuan; Zhang, Nan-Ping; Cheng, Xian-Long; Guo, Zeng-Xi; Ma, Shuang-Cheng; Wei, Feng

2017-07-01

The Chinese Materia Medica, Tiepishihu, used as a tonic for over one thousand years, is a well-known precious medicine in China. According to the Chinese Pharmacopoeia, its source is the species Dendrobium officinale Kimura et Migo, which is distinguished from other species in Dendrobium genus. However, these species from the same genus are similar with Tiepishihu and caused confusion in the market. To find a quick and simple method to distinguish Tiepishihu from other similar species, histologic and microscopic methods were combined together to investigate the transverse section of stem of Tiepishihu and other similar species. Phloroglucinol test solution with hydrochloric acid was used to reveal the lignified tissue by staining the transverse section of Tiepishihu and similar species. Results revealed the unique identification characteristics to distinguish Tiepishihu from similar species, which were difficult to distinguish by other methods. The identification characteristics of Tiepishihu include the cells of vascular bundle sheath were stained red, parenchyma cells were not stained red. What's more, other species can be distinguished from each other with microscopic and histological characteristics. These characteristics proved stable and can be easily observed by normal light microscopic examination. This method is rapid, accurate, stable, and inexpensive. © 2017 Wiley Periodicals, Inc.

Pepper pectin methylesterase inhibitor protein CaPMEI1 is required for antifungal activity, basal disease resistance and abiotic stress tolerance.

PubMed

An, Soo Hyun; Sohn, Kee Hoon; Choi, Hyong Woo; Hwang, In Sun; Lee, Sung Chul; Hwang, Byung Kook

2008-06-01

Pectin is one of the main components of the plant cell wall that functions as the primary barrier against pathogens. Among the extracellular pectinolytic enzymes, pectin methylesterase (PME) demethylesterifies pectin, which is secreted into the cell wall in a highly methylesterified form. Here, we isolated and functionally characterized the pepper (Capsicum annuum L.) gene CaPMEI1, which encodes a pectin methylesterase inhibitor protein (PMEI), in pepper leaves infected by Xanthomonas campestris pv. vesicatoria (Xcv). CaPMEI1 transcripts are localized in the xylem of vascular bundles in leaf tissues, and pathogens and abiotic stresses can induce differential expression of this gene. Purified recombinant CaPMEI1 protein not only inhibits PME, but also exhibits antifungal activity against some plant pathogenic fungi. Virus-induced gene silencing of CaPMEI1 in pepper confers enhanced susceptibility to Xcv, accompanied by suppressed expression of some defense-related genes. Transgenic Arabidopsis CaPMEI1-overexpression lines exhibit enhanced resistance to Pseudomonas syringae pv. tomato, mannitol and methyl viologen, but not to the biotrophic pathogen Hyaloperonospora parasitica. Together, these results suggest that CaPMEI1, an antifungal protein, may be involved in basal disease resistance, as well as in drought and oxidative stress tolerance in plants.

[Screening and identification of endophytic fungi with growth promoting effect on Dendrobium officinale].

PubMed

Hou, Xiao-qiang; Guo, Shun-xing

2014-09-01

The endophytic fungi with plant growth promoting effects were screened by co-culture of each endophytic fungus and seedlings of Dendrobium officinale. Anatomical features of the inoculated roots were studied by paraffin sectioning. Morphological characteristics and rDNA ITS1-5. 8S-ITS2 sequences were applied for the taxonomy of endophytic fungi. The results showed that 8 strains inoculated to D. officinale seedlings greatly enhanced plant height, stem diameter, new roots number and biomass. According to the anatomical features of the inoculated roots, each fungus could infect the velamina of seedlings. The hyphae or pelotons were existed in the exodermis passage cells and cortex cells. The effective fungi could not infect the endodermis and vascular bundle sheath, but which was exception for other fungi with harmful to seedlings. Combined with classic morphologic classification, 2 effective strains were identified which were subjected to Pestalotiopsis and Eurotium. Six species of fungi without conidiophore belonged to Pyrenochaeta, Coprinellus, Pholiota, Alternaria, Helotiales, which were identified by sequencing the PCR-amplified rDNA ITS1-5. 8S-ITS2 regions. The co-culture technology of effective endophytic fungi and plant can apply to cultivate the seedlings of D. officinale. It is feasible to shorten growth cycle of D. officinale and increase the resource of Chinese herbs.

Tension and Elasticity Contribute to Fibroblast Cell Shape in Three Dimensions.

PubMed

Brand, Christoph A; Linke, Marco; Weißenbruch, Kai; Richter, Benjamin; Bastmeyer, Martin; Schwarz, Ulrich S

2017-08-22

The shape of animal cells is an important regulator for many essential processes such as cell migration or division. It is strongly determined by the organization of the actin cytoskeleton, which is also the main regulator of cell forces. Quantitative analysis of cell shape helps to reveal the physical processes underlying cell shape and forces, but it is notoriously difficult to conduct it in three dimensions. Here we use direct laser writing to create 3D open scaffolds for adhesion of connective tissue cells through well-defined adhesion platforms. Due to actomyosin contractility in the cell contour, characteristic invaginations lined by actin bundles form between adjacent adhesion sites. Using quantitative image processing and mathematical modeling, we demonstrate that the resulting shapes are determined not only by contractility, but also by elastic stress in the peripheral actin bundles. In this way, cells can generate higher forces than through contractility alone. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Microparticle Shedding from Neural Progenitor Cells and Vascular Compartment Cells Is Increased in Ischemic Stroke.

PubMed

Chiva-Blanch, Gemma; Suades, Rosa; Crespo, Javier; Peña, Esther; Padró, Teresa; Jiménez-Xarrié, Elena; Martí-Fàbregas, Joan; Badimon, Lina

2016-01-01

Ischemic stroke has shown to induce platelet and endothelial microparticle shedding, but whether stroke induces microparticle shedding from additional blood and vascular compartment cells is unclear. Neural precursor cells have been shown to replace dying neurons at sites of brain injury; however, if neural precursor cell activation is associated to microparticle shedding, and whether this activation is maintained at long term and associates to stroke type and severity remains unknown. We analyzed neural precursor cells and blood and vascular compartment cells microparticle shedding after an acute ischemic stroke. Forty-four patients were included in the study within the first 48h after the onset of stroke. The cerebral lesion size was evaluated at 3-7 days of the stroke. Circulating microparticles from neural precursor cells and blood and vascular compartment cells (platelets, endothelial cells, erythrocytes, leukocytes, lymphocytes, monocytes and smooth muscle cells) were analyzed by flow cytometry at the onset of stroke and at 7 and 90 days. Forty-four age-matched high cardiovascular risk subjects without documented vascular disease were used as controls. Compared to high cardiovascular risk controls, patients showed higher number of neural precursor cell- and all blood and vascular compartment cell-derived microparticles at the onset of stroke, and after 7 and 90 days. At 90 days, neural precursor cell-derived microparticles decreased and smooth muscle cell-derived microparticles increased compared to levels at the onset of stroke, but only in those patients with the highest stroke-induced cerebral lesions. Stroke increases blood and vascular compartment cell and neural precursor cell microparticle shedding, an effect that is chronically maintained up to 90 days after the ischemic event. These results show that stroke induces a generalized blood and vascular cell activation and the initiation of neuronal cell repair process after stroke. Larger cerebral lesions associate with deeper vessel injury affecting vascular smooth muscle cells.

Microparticle Shedding from Neural Progenitor Cells and Vascular Compartment Cells Is Increased in Ischemic Stroke

PubMed Central

Chiva-Blanch, Gemma; Suades, Rosa; Crespo, Javier; Peña, Esther; Padró, Teresa; Jiménez-Xarrié, Elena; Martí-Fàbregas, Joan; Badimon, Lina

2016-01-01

Purpose Ischemic stroke has shown to induce platelet and endothelial microparticle shedding, but whether stroke induces microparticle shedding from additional blood and vascular compartment cells is unclear. Neural precursor cells have been shown to replace dying neurons at sites of brain injury; however, if neural precursor cell activation is associated to microparticle shedding, and whether this activation is maintained at long term and associates to stroke type and severity remains unknown. We analyzed neural precursor cells and blood and vascular compartment cells microparticle shedding after an acute ischemic stroke. Methods Forty-four patients were included in the study within the first 48h after the onset of stroke. The cerebral lesion size was evaluated at 3–7 days of the stroke. Circulating microparticles from neural precursor cells and blood and vascular compartment cells (platelets, endothelial cells, erythrocytes, leukocytes, lymphocytes, monocytes and smooth muscle cells) were analyzed by flow cytometry at the onset of stroke and at 7 and 90 days. Forty-four age-matched high cardiovascular risk subjects without documented vascular disease were used as controls. Results Compared to high cardiovascular risk controls, patients showed higher number of neural precursor cell- and all blood and vascular compartment cell-derived microparticles at the onset of stroke, and after 7 and 90 days. At 90 days, neural precursor cell-derived microparticles decreased and smooth muscle cell-derived microparticles increased compared to levels at the onset of stroke, but only in those patients with the highest stroke-induced cerebral lesions. Conclusions Stroke increases blood and vascular compartment cell and neural precursor cell microparticle shedding, an effect that is chronically maintained up to 90 days after the ischemic event. These results show that stroke induces a generalized blood and vascular cell activation and the initiation of neuronal cell repair process after stroke. Larger cerebral lesions associate with deeper vessel injury affecting vascular smooth muscle cells. PMID:26815842

Cytoplasmic pH dynamics in maize pulvinal cells induced by gravity vector changes

NASA Technical Reports Server (NTRS)

Johannes, E.; Collings, D. A.; Rink, J. C.; Allen, N. S.; Brown, C. S. (Principal Investigator)

2001-01-01

In maize (Zea mays) and other grasses, changes in orientation of stems are perceived by pulvinal tissue, which responds to the stimulus by differential growth resulting in upward bending of the stem. The amyloplast-containing bundle sheath cells are the sites of gravity perception, although the initial steps of gravity perception and transmission remain unclear. In columella cells of Arabidopsis roots, we previously found that cytoplasmic pH (pH(c)) is a mediator in early gravitropic signaling (A.C. Scott, N.S. Allen [1999] Plant Physiol 121: 1291-1298). The question arises whether pH(c) has a more general role in signaling gravity vector changes. Using confocal ratiometric imaging and the fluorescent pH indicator carboxy seminaphtorhodafluor acetoxymethyl ester acetate, we measured pH(c) in the cells composing the maize pulvinus. When stem slices were gravistimulated and imaged on a horizontally mounted confocal microscope, pH(c) changes were only apparent within the bundle sheath cells, and not in the parenchyma cells. After turning, cytoplasmic acidification was observed at the sides of the cells, whereas the cytoplasm at the base of the cells where plastids slowly accumulated became more basic. These changes were most apparent in cells exhibiting net amyloplast sedimentation. Parenchyma cells and isolated bundle sheath cells did not show any gravity-induced pH(c) changes although all cell types responded to external stimuli in the predicted way: Propionic acid and auxin treatments induced acidification, whereas raising the external pH caused alkalinization. The results suggest that pH(c) has an important role in the early signaling pathways of maize stem gravitropism.

Aphidicolin-induced nuclear elongation in tobacco BY-2 cells.

PubMed

Yasuhara, Hiroki; Kitamoto, Kazuki

2014-05-01

Plant nuclei are known to differentiate into various shapes within a single plant. However, little is known about the mechanisms of nuclear morphogenesis. We found that nuclei of tobacco BY-2 cells were highly elongated on long-term treatment with 5 mg l⁻¹ aphidicolin, an inhibitor of DNA polymerase α. In aphidicolin-treated cells, the nuclear length was correlated with the cell length. During culture in the presence of aphidicolin, the nuclei were elongated in parallel with cell elongation. Nuclear elongation was inhibited by the inhibition of cell elongation with 2,6-dichlorobenzonitrile, a cellulose synthesis inhibitor. However, cell elongation induced in the auxin-depleted medium in the absence of aphidicolin did not cause nuclear elongation, indicating that cell elongation alone is not sufficient for nuclear elongation. Treatment with either latrunculin B or propyzamide inhibited the aphidicolin-induced nuclear elongation, indicating that both actin filaments and microtubules (MTs) are required for nuclear elongation. Observations using BY-YTHCLR2 cells, in which actin filaments, MTs and nuclei were simultaneously visualized, revealed that the longitudinally arranged MT bundles associated with the nucleus play an important role in nuclear elongation, and that actin filaments affect the formation of these MT bundles. In aphidicolin-treated cells, the nuclear DNA contents of the elongated nuclei exceeded 4C, and the nuclear length was highly correlated with the nuclear DNA content. In cells treated with 50 mg l⁻¹ aphidicolin, cells were elongated and nucleus-associated longitudinal MT bundles were formed, but the nuclear DNA contents did not exceed 4C and the nuclei did not elongate. These results indicate that an increase in the nuclear DNA content above 4C is also required for nuclear elongation.

Morphological study of the atrioventricular conduction system and Purkinje fibers in yak.

PubMed

Duan, Deyong; Yu, Sijiu; Cui, Yan; Li, Chaoxu

2017-07-01

We studied the morphology of the atrioventricular conduction system (AVCS) and Purkinje fibers of the yak. Light and transmission electron microscopy were used to study the histological features of AVCS. The distributional characteristics of the His-bundle, the left bundle branch (LBB), right bundle branch (RBB), and Purkinje fiber network of yak hearts were examined using gross dissection, ink injection, and ABS casting. The results showed that the atrioventricular node (AVN) of yak located in the right side of interatrial septum and had a flattened ovoid shape. The AVN of yak is composed of the slender, interweaving cells formed almost entirely of the transitional cells (T-cells). The His-bundle extended from the AVN, and split into left LBB and RBB at the crest of the interventricular septum. The LBB descended along the left side of interventricular septum. At approximately the upper 1/3 of the interventricular septum, the LBB typically divided into three branches. The RBB ran under the endocardium of the right side of interventricular septum, and extended to the base of septal papillary muscle, passed into the moderator band, crossed the right ventricular cavity to reach the base of anterior papillary muscle, and divided into four fascicles under the subendocardial layer. The Purkinje fibers in the ventricle formed a complex spatial network. The distributional and cellular component characteristics of the AVCS and Purkinje fibers ensured normal cardiac function. © 2017 Wiley Periodicals, Inc.

Fascial structures and autonomic nerves in the female pelvis: a study using macroscopic slices and their corresponding histology.

PubMed

Tamakawa, Mitsuharu; Murakami, Gen; Takashima, Ken; Kato, Tomoyasu; Hareyama, Masato

2003-12-01

We investigated the topographical anatomy of the pelvic fasciae and autonomic nerves using macroscopic slices of five decalcified female pelves. The lateral aspect of the supravaginal cervix uteri and superior-most vagina issued abundant thick fiber bundles. These visceral fibrous tissues extended dorsolaterally, joined another fibrous tissue from the rectum (the actual lateral ligament of the rectum) and attached to the parietal fibrous tissues at and around the sciatic foramina (i.e. the sacrospinous ligament, thick fasciae of the coccygeus and piriformis and dorsal end of the covering fascia of the levator ani). The inferior or ventral vagina also issued thick fiber bundles communicating with the levator ani fascia. This connection between the vagina and levator fascia, when stretched, seemed to provide a macroscopic morphology called the arcus tendineus fasciae pelvis. The overall morphology of the visceroparietal fascial bridge exhibited a bilateral wing-like shape. The fascial bridge complex was adjacent but dorso-inferior to the internal iliac vascular sheath and located slightly ventral to the pelvic splanchnic nerve. However, the pelvic plexus and its peripheral branches were embedded in the fascial complex. The hypogastric nerve ran along and beneath the uterosacral peritoneal fold, which did not contain thick fibrous tissue. During surgery, in combination with the superficially located vascular sheath, the morphology of the visceroparietal fascial bridge and associated nerves seemed to be artificially changed and developed into the so-called cardinal, uterosacral, uterovesical and/or rectal lateral ligaments. The classical and original concepts of these pelvic fascial structures may need to be altered to adjust to these surgical observations.

Wide-field and high-resolution optical imaging for early detection of oral neoplasia

NASA Astrophysics Data System (ADS)

Pierce, Mark C.; Schwarz, Richard A.; Rosbach, Kelsey; Roblyer, Darren; Muldoon, Tim; Williams, Michelle D.; El-Naggar, Adel K.; Gillenwater, Ann M.; Richards-Kortum, Rebecca

2010-02-01

Current procedures for oral cancer screening typically involve visual inspection of the entire tissue surface at risk under white light illumination. However, pre-cancerous lesions can be difficult to distinguish from many benign conditions when viewed under these conditions. We have developed wide-field (macroscopic) imaging system which additionally images in cross-polarized white light, narrowband reflectance, and fluorescence imaging modes to reduce specular glare, enhance vascular contrast, and detect disease-related alterations in tissue autofluorescence. We have also developed a portable system to enable high-resolution (microscopic) evaluation of cellular features within the oral mucosa in situ. This system is a wide-field epi-fluorescence microscope coupled to a 1 mm diameter, flexible fiber-optic imaging bundle. Proflavine solution was used to specifically label cell nuclei, enabling the characteristic differences in N/C ratio and nuclear distribution between normal, dysplastic, and cancerous oral mucosa to be quantified. This paper discusses the technical design and performance characteristics of these complementary imaging systems. We will also present data from ongoing clinical studies aimed at evaluating diagnostic performance of these systems for detection of oral neoplasia.

Influence of blue light on the leaf morphoanatomy of in vitro Kalanchoe pinnata (Lamarck) Persoon (Crassulaceae).

PubMed

Leal-Costa, Marcos Vinicius; Nascimento, Luana Beatriz dos Santos; Moreira, Nattacha dos Santos; Reinert, Fernanda; Costa, Sônia Soares; Lage, Celso Luiz Salgueiro; Tavares, Eliana Schwartz

2010-10-01

Kalanchoe pinnata (Lamarck) Persoon (Crassulaceae) (air plant, miracle leaf) is popularly used to treat gastrointestinal disorders and wounds. Recently, the species was tested to treat cutaneous leishmaniasis with successful results. This medicinal activity was associated with the phenolic fraction of the plant. Blue light induces biosynthesis of phenolic compounds and many changes in anatomical characteristics. We studied the effects of supplementary blue light on the leaf morphology of in vitro K. pinnata. Plants cultured under white light (W plants) only and white light plus blue light (WB plants) show petioles with plain-convex section, amphistomatic leaf blades with simple epidermis, homogeneous mesophyll with densely packed cells, and a single collateral vascular bundle in the midrib. W plants have longer branches, a larger number of nodes per branch, and smaller leaves, whereas WB plant leaves have a thicker upper epidermis and mesophyll. Leaf fresh weight and leaf dry weight were similar in both treatments. Phenolic idioblasts were observed in the plants supplemented with blue light, suggesting that blue light plays an important role in the biosynthesis of phenolic compounds in K. pinnata.

Scaffolding for Three-Dimensional Embryonic Vasculogenesis

NASA Astrophysics Data System (ADS)

Kraehenbuehl, Thomas P.; Aday, Sezin; Ferreira, Lino S.

Biomaterial scaffolds have great potential to support efficient vascular differentiation of embryonic stem cells. Vascular cell fate-specific biochemical and biophysical cues have been identified and incorporated into three-dimensional (3D) biomaterials to efficiently direct embryonic vasculogenesis. The resulting vascular-like tissue can be used for regenerative medicine applications, further elucidation of biophysical and biochemical cues governing vasculogenesis, and drug discovery. In this chapter, we give an overview on the following: (1) developmental cues for directed differentiation of human embryonic stem cells (hESCs) into vascular cells, (2) 3D vascular differentiation in embryoid bodies (EBs), (3) preparation of 3D scaffolds for the vascular differentiation of hESCs, and (4) the most significant studies combining scaffolding and hESCs for development of vascular-like tissue.

Unique photosynthetic phenotypes in Portulaca (Portulacaceae): C3-C4 intermediates and NAD-ME C4 species with Pilosoid-type Kranz anatomy.

PubMed

Voznesenskaya, Elena V; Koteyeva, Nuria K; Edwards, Gerald E; Ocampo, Gilberto

2017-01-01

Portulacaceae is a family that has considerable diversity in photosynthetic phenotypes. It is one of 19 families of terrestrial plants where species having C 4 photosynthesis have been found. Most species in Portulaca are in the alternate-leaved (AL) lineage, which includes one clade (Cryptopetala) with taxa lacking C 4 photosynthesis and three clades having C 4 species (Oleracea, Umbraticola and Pilosa). All three species in the Cryptopetala clade lack Kranz anatomy, the leaves have C 3 -like carbon isotope composition and they have low levels of C 4 cycle enzymes. Anatomical, biochemical and physiological analyses show they are all C 3 -C 4 intermediates. They have intermediate CO 2 compensation points, enrichment of organelles in the centripetal position in bundle sheath (BS) cells, with selective localization of glycine decarboxylase in BS mitochondria. In the three C 4 clades there are differences in Kranz anatomy types and form of malic enzyme (ME) reported to function in C 4 (NAD-ME versus NADP-ME): Oleracea (Atriplicoid, NAD-ME), Umbraticola (Atriplicoid, NADP-ME) and Pilosa (Pilosoid, NADP-ME). Structural and biochemical analyses were performed on Pilosa clade representatives having Pilosoid-type leaf anatomy with Kranz tissue enclosing individual peripheral vascular bundles and water storage in the center of the leaf. In this clade, all species except P. elatior are NADP-ME-type C 4 species with grana-deficient BS chloroplasts and grana-enriched M chloroplasts. Surprisingly, P. elatior has BS chloroplasts enriched in grana and NAD-ME-type photosynthesis. The results suggest photosynthetic phenotypes were probably derived from an ancestor with NADP-ME-type C 4 , with two independent switches to NAD-ME type. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Regulation of leaf hydraulics: from molecular to whole plant levels.

PubMed

Prado, Karine; Maurel, Christophe

2013-01-01

The water status of plant leaves is dependent on both stomatal regulation and water supply from the vasculature to inner tissues. The present review addresses the multiple physiological and mechanistic facets of the latter process. Inner leaf tissues contribute to at least a third of the whole resistance to water flow within the plant. Physiological studies indicated that leaf hydraulic conductance (K leaf) is highly dependent on the anatomy, development and age of the leaf and can vary rapidly in response to physiological or environmental factors such as leaf hydration, light, temperature, or nutrient supply. Differences in venation pattern provide a basis for variations in K leaf during development and between species. On a short time (hour) scale, the hydraulic resistance of the vessels can be influenced by transpiration-induced cavitations, wall collapses, and changes in xylem sap composition. The extravascular compartment includes all living tissues (xylem parenchyma, bundle sheath, and mesophyll) that transport water from xylem vessels to substomatal chambers. Pharmacological inhibition and reverse genetics studies have shown that this compartment involves water channel proteins called aquaporins (AQPs) that facilitate water transport across cell membranes. In many plant species, AQPs are present in all leaf tissues with a preferential expression in the vascular bundles. The various mechanisms that allow adjustment of K leaf to specific environmental conditions include transcriptional regulation of AQPs and changes in their abundance, trafficking, and intrinsic activity. Finally, the hydraulics of inner leaf tissues can have a strong impact on the dynamic responses of leaf water potential and stomata, and as a consequence on plant carbon economy and leaf expansion growth. The manipulation of these functions could help optimize the entire plant performance and its adaptation to extreme conditions over short and long time scales.

Regulation of leaf hydraulics: from molecular to whole plant levels

PubMed Central

Prado, Karine; Maurel, Christophe

2013-01-01

The water status of plant leaves is dependent on both stomatal regulation and water supply from the vasculature to inner tissues. The present review addresses the multiple physiological and mechanistic facets of the latter process. Inner leaf tissues contribute to at least a third of the whole resistance to water flow within the plant. Physiological studies indicated that leaf hydraulic conductance (Kleaf) is highly dependent on the anatomy, development and age of the leaf and can vary rapidly in response to physiological or environmental factors such as leaf hydration, light, temperature, or nutrient supply. Differences in venation pattern provide a basis for variations in Kleaf during development and between species. On a short time (hour) scale, the hydraulic resistance of the vessels can be influenced by transpiration-induced cavitations, wall collapses, and changes in xylem sap composition. The extravascular compartment includes all living tissues (xylem parenchyma, bundle sheath, and mesophyll) that transport water from xylem vessels to substomatal chambers. Pharmacological inhibition and reverse genetics studies have shown that this compartment involves water channel proteins called aquaporins (AQPs) that facilitate water transport across cell membranes. In many plant species, AQPs are present in all leaf tissues with a preferential expression in the vascular bundles. The various mechanisms that allow adjustment of Kleaf to specific environmental conditions include transcriptional regulation of AQPs and changes in their abundance, trafficking, and intrinsic activity. Finally, the hydraulics of inner leaf tissues can have a strong impact on the dynamic responses of leaf water potential and stomata, and as a consequence on plant carbon economy and leaf expansion growth. The manipulation of these functions could help optimize the entire plant performance and its adaptation to extreme conditions over short and long time scales. PMID:23874349

Water retained in tall Cryptomeria japonica leaves as studied by infrared micro-spectroscopy.

PubMed

Azuma, Wakana; Nakashima, Satoru; Yamakita, Eri; Ishii, H Roaki; Kuroda, Keiko

2017-10-01

Recent studies in the tallest tree species suggest that physiological and anatomical traits of tree-top leaves are adapted to water-limited conditions. In order to examine water retention mechanism of leaves in a tall tree, infrared (IR) micro-spectroscopy was conducted on mature leaf cross-sections of tall Cryptomeria japonica D. Don from four different heights (51, 43, 31 and 19 m). We measured IR transmission spectra and mainly analyzed OH (3700-3000 cm-1) and C-O (1190-845 cm-1) absorption bands, indicating water molecules and sugar groups, respectively. The changes in IR spectra of leaf sections from different heights were compared with bulk-leaf hydraulics. Both average OH band area of the leaf sections and leaf water content were larger in the upper-crown, while osmotic potential at saturation did not vary with height, suggesting higher dissolved sugar contents of upper-crown leaves. As cell-wall is the main cellular structure of leaves, we inferred that larger average C-O band area of upper-crown leaves reflected higher content of structural polysaccharides such as cellulose, hemicellulose and pectin. Infrared micro-spectroscopic imaging showed that the OH and C-O band areas are large in the vascular bundle, transfusion tissue and epidermis. Infrared spectra of individual tissue showed that much more water is retained in vascular bundle and transfusion tissue than mesophyll. These results demonstrate that IR micro-spectroscopy is a powerful tool for visualizing detailed, quantitative information on the spatial distribution of chemical substances within plant tissues, which cannot be done using conventional methods like histochemical staining. The OH band could be well reproduced by four Gaussian OH components around 3530 (free water: long H bond), 3410 (pectin-like OH species), 3310 (cellulose-like OH species) and 3210 (bound water: short H bond) cm-1, and all of these OH components were higher in the upper crown while their relative proportions did not vary with height. Based on the spectral analyses, we inferred that polysaccharides play a key role in biomolecular retention of water in leaves of tall C. japonica. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Hedgehog and Resident Vascular Stem Cell Fate

PubMed Central

Mooney, Ciaran J.; Hakimjavadi, Roya; Fitzpatrick, Emma; Kennedy, Eimear; Walls, Dermot; Morrow, David; Redmond, Eileen M.; Cahill, Paul A.

2015-01-01

The Hedgehog pathway is a pivotal morphogenic driver during embryonic development and a key regulator of adult stem cell self-renewal. The discovery of resident multipotent vascular stem cells and adventitial progenitors within the vessel wall has transformed our understanding of the origin of medial and neointimal vascular smooth muscle cells (SMCs) during vessel repair in response to injury, lesion formation, and overall disease progression. This review highlights the importance of components of the Hh and Notch signalling pathways within the medial and adventitial regions of adult vessels, their recapitulation following vascular injury and disease progression, and their putative role in the maintenance and differentiation of resident vascular stem cells to vascular lineages from discrete niches within the vessel wall. PMID:26064136

Leaf blade structure of Verbesina macrophylla (Cass.) F. S. Blake (Asteraceae): ontogeny, duct secretion mechanism and essential oil composition.

PubMed

Bezerra, L D A; Mangabeira, P A O; de Oliveira, R A; Costa, L C D B; Da Cunha, M

2018-05-01

Secretory structures are common in Asteraceae, where they exhibit a high degree of morphological diversity. The species Verbesina macrophylla, popularly known as assa-peixe, is native to Brazil where it is widely used for medicinal purposes. Despite its potential medical importance, there have been no studies of the anatomy of this species, especially its secretory structures and secreted compounds. This study examined leaves of V. macrophylla with emphasis on secretory structures and secreted secondary metabolites. Development of secretory ducts and the mechanism of secretion production are described for V. macrophylla using ultrastructure, yield and chemical composition of its essential oils. Verbesina macrophylla has a hypostomatic leaf blade with dorsiventral mesophyll and secretory ducts associated with vascular bundles of schizogenous origin. Histochemistry identified the presence of lipids, terpenes, alkaloids and mucopolysaccharides. Ultrastructure suggests that the secretion released into the duct lumen is produced in plastids of transfer cells, parenchymal sheath cells and stored in vacuoles in these cells and duct epithelial cells. The essential oil content was 0.8%, and its major components were germacrene D, germacrene D-4-ol, β-caryophyllene, bicyclogermacrene and α-cadinol. Secretory ducts of V. macrophylla are squizogenous. Substances identified in tissues suggest that both secretions stored in the ducts and in adjacent parenchyma cells are involved in chemical defence. The essential oil is rich in sesquiterpenes, with germacrene D and its derivatives being notable components. © 2018 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.

A comparison of the hydraulic efficiency of a palm species (Iriartea deltoidea) with other wood types.

PubMed

Renninger, Heidi J; McCulloh, Katherine A; Phillips, Nathan

2013-02-01

Palms are an important component of tropical ecosystems, living alongside dicotyledonous trees, even though they have a very different growth pattern and vascular system. As monocots, vessels in palms are located within vascular bundles and, without a vascular cambium that many dicotyledonous trees possess, palms cannot add additional vessels to their vascular system as they get older and taller. This means that hydraulic architecture in palms is more predetermined, which may require a highly efficient hydraulic system. This preset nature, along with the decoupling of hydraulic and mechanical functioning to different cell types, may allow palms to have a more efficient hydraulic system than dicotyledonous trees. Therefore, this study seeks to determine the efficiency of the hydraulic system in the palm Iriartea deltoidea (Ruiz & Pav.) and compare this efficiency with other tree forms. We measured cross-sectional areas of roots, stems and fronds as well as leaf areas of I. deltoidea saplings. Likewise, cross-sections were made and vessel diameters and frequencies measured. This allowed for the calculation of theoretical specific conductivity (K(S,calc)), theoretical leaf-specific conductivity (K(L,calc)), and vessel diameter and vessel number ratios between distal and proximal locations in the palms. Iriartea deltoidea palms were found to have the largest, least frequent vessels that diverged most from the square packing limit (maximum number of vessels that fit into a given area) compared with other major tree forms, and they therefore invested the least space and carbon into water transport structures. Likewise, conduits tapered by ∼1/3 between ranks (root, bole and petiole), which represents an efficient ratio with regard to the trade-offs between safety and efficiency of the conducting system. Conduits also exhibited a high conservation of the sum of the conduit radii cubed (Σr(3)) across ranks, thereby approximating Murray's law patterning. Therefore, our results indicate that the palm I. deltoidea has a very efficient hydraulic system in terms of maintaining a large conducting capacity with a minimal vascular investment. This efficiency may allow palms to compete well with dicotyledonous trees in tropical and subtropical climates but other developmental factors largely restrict palms from regions that experience prolonged freezing temperatures.

Assembly kinetics determine the architecture of α-actinin crosslinked F-actin networks.

PubMed

Falzone, Tobias T; Lenz, Martin; Kovar, David R; Gardel, Margaret L

2012-05-29

The actin cytoskeleton is organized into diverse meshworks and bundles that support many aspects of cell physiology. Understanding the self-assembly of these actin-based structures is essential for developing predictive models of cytoskeletal organization. Here we show that the competing kinetics of bundle formation with the onset of dynamic arrest arising from filament entanglements and crosslinking determine the architecture of reconstituted actin networks formed with α-actinin crosslinks. Crosslink-mediated bundle formation only occurs in dilute solutions of highly mobile actin filaments. As actin polymerization proceeds, filament mobility and bundle formation are arrested concomitantly. By controlling the onset of dynamic arrest, perturbations to actin assembly kinetics dramatically alter the architecture of biochemically identical samples. Thus, the morphology of reconstituted F-actin networks is a kinetically determined structure similar to those formed by physical gels and glasses. These results establish mechanisms controlling the structure and mechanics in diverse semiflexible biopolymer networks.

Microtubules and epithem-cell morphogenesis in hydathodes of Pilea cadierei.

PubMed

Galatis, B

1988-12-01

When cell divisions have ceased, the epithem of the hydathodes of Pilea cadierei Gagnep. et Guill. consists of small polyhedral cells exhibiting a meristematic appearance, and completely lacks intercellular spaces. The cortical microtubules in epithem cells exhibit a unique organization: they are not scattered along the whole wall surface but form groups lying at some distance from each other. In sections, from two to eight groups of microtubules can be observed, each lining a wall region averaging between 0.5 and 1.5 μm in length. These groups represent sections of microtubule bundles girdling a major part or the whole of the cell periphery. They are connected to one another by anastomoses, forming a microtubular reticulum. The assembly of microtubule bundles is followed by the appearance of distinct local thickenings in the adjacent wall areas. The cellulose microfibrils in the thickenings are deposited in parallel to the underlying microtubules. Gradually, the vacuolating epithem cells undergo swelling, except for the areas bounded by the wall thickenings. Since the latter, and actually their constituent bundles of cellulose microfibrils, cannot extend in length the differential cell growth results in schizogenous formation of intercellular spaces between contiguous cell walls at their thickened regions. The spaces then broaden and merge to become an extensive intercellular space system. As a result of the above processes, the epithem cells become constricted and finally deeply lobed. The observations show that (i) the cortical microtubules are intimately involved in the morphogenesis of the epithem cells and (ii) the initiation and development of the epithem intercellular spaces is a phenomenon directly related to cell morphogenesis and therefore to the cortical microtubule cytoskeleton. The sites of initiation of these spaces are highly predictable.

The actin-binding proteins eps8 and gelsolin have complementary roles in regulating the growth and stability of mechanosensory hair bundles of mammalian cochlear outer hair cells.

PubMed

Olt, Jennifer; Mburu, Philomena; Johnson, Stuart L; Parker, Andy; Kuhn, Stephanie; Bowl, Mike; Marcotti, Walter; Brown, Steve D M

2014-01-01

Sound transduction depends upon mechanosensitive channels localized on the hair-like bundles that project from the apical surface of cochlear hair cells. Hair bundles show a stair-case structure composed of rows of stereocilia, and each stereocilium contains a core of tightly-packed and uniformly-polarized actin filaments. The growth and maintenance of the stereociliary actin core are dynamically regulated. Recently, it was shown that the actin-binding protein gelsolin is expressed in the stereocilia of outer hair cells (OHCs) and in its absence they become long and straggly. Gelsolin is part of a whirlin scaffolding protein complex at the stereocilia tip, which has been shown to interact with other actin regulatory molecules such as Eps8. Here we investigated the physiological effects associated with the absence of gelsolin and its possible overlapping role with Eps8. We found that, in contrast to Eps8, gelsolin does not affect mechanoelectrical transduction during immature stages of development. Moreover, OHCs from gelsolin knockout mice were able to mature into fully functional sensory receptors as judged by the normal resting membrane potential and basolateral membrane currents. Mechanoelectrical transducer current in gelsolin-Eps8 double knockout mice showed a profile similar to that observed in the single mutants for Eps8. We propose that gelsolin has a non-overlapping role with Eps8. While Eps8 is mainly involved in the initial growth of stereocilia in both inner hair cells (IHCs) and OHCs, gelsolin is required for the maintenance of mature hair bundles of low-frequency OHCs after the onset of hearing.

Noise alters hair-bundle mechanics at the cochlear apex

NASA Astrophysics Data System (ADS)

Strimbu, C. Elliott; Fridberger, Anders

2015-12-01

Exposure to loud sounds can lead to both permanent and short term changes in auditory sensitivity. Permanent hearing loss is often associated with gross changes in cochlear morphology including the loss of hair cells and auditory nerve fibers while the mechanisms of short term threshold shifts are much less well understood and may vary at different locations across the cochlea. Previous reports suggest that exposure to loud sounds leads to a decrease in the cochlear microphonic potential and in the stiffness of the organ of Corti. Because the cochlear microphonic reflects changes in the membrane potential of the hair cells, this suggests that hair-bundle motion should be reversibly altered following exposure to loud sounds. Using an in vitro preparation of the guinea pig temporal bone we investigate changes in the micro-mechanical response near the cochlear apex following a brief (up to 10 - 20 minutes) exposure to loud (˜ 120 dB) tones near the best frequency at this location. We use time-resolved confocal imaging to record the motion of outer hair cell bundles before and after acoustic overstimulation. We have also recorded larger-scale structural views of the organ of Corti before and after exposure to the loud sound. Conventional electrophysiological techniques are used measure the cochlear microphonic potential. As has been previously reported, following acoustic overexposure the cochlear microphonic declines in value and typically recovers on the order of 30 - 60 minutes. Hair-bundle trajectories are affected following the loud sound and typically recover on a somewhat faster time scale than the microphonic potential, although the results vary considerably across preparations. Preliminary results also suggest reversible changes in the hair cell's resting potential following the loud sound.

Hematopoietic Stem Cell Capture and Directional Differentiation into Vascular Endothelial Cells for Metal Stent-Coated Chitosan/Hyaluronic Acid Loading CD133 Antibody

PubMed Central

Zhang, Fan; Feng, Bo; Fan, Qingyu; Yang, Feng; Shang, Debin; Sui, Jinghan; Zhao, Hong

2015-01-01

A series of metal stents coated with chitosan/hyaluronic acid (CS/HA) loading antibodies by electrostatic self-assembled method were prepared, and the types of cells captured by antibodies and their differentiation in vascular endothelial cells (ECs) evaluated by molecular biology and scanning electron microscope. The results showed that CD133 stent can selectively capture hematopoietic stem cells (HSC),which directionally differentiate into vascular ECs in peripheral blood by (CS/HA) induction, and simultaneously inhibit migration and proliferation of immune cells and vascular smooth muscle cells (MCs). CD34 stent can capture HSC, hematopoietic progenitor cells that differentiate into vascular ECs and immune cells, promoting smooth MCs growth, leading to thrombosis, inflammation, and rejection. CD133 stent can be implanted into miniature pig heart coronary and can repair vascular damage by capturing own HSC, thus contributing to the rapid natural vascular repair, avoiding inflammation and rejection, thrombosis and restenosis. These studies demonstrated that CD133 stent of HSC capture will be an ideal coated metal stent providing a new therapeutic approach for cardiovascular and cerebrovascular disease. PMID:25404533

Visualizing heterogeneity of photosynthetic properties of plant leaves with two-photon fluorescence lifetime imaging microscopy.

PubMed

Iermak, Ievgeniia; Vink, Jochem; Bader, Arjen N; Wientjes, Emilie; van Amerongen, Herbert

2016-09-01

Two-photon fluorescence lifetime imaging microscopy (FLIM) was used to analyse the distribution and properties of Photosystem I (PSI) and Photosystem II (PSII) in palisade and spongy chloroplasts of leaves from the C3 plant Arabidopsis thaliana and the C4 plant Miscanthus x giganteus. This was achieved by separating the time-resolved fluorescence of PSI and PSII in the leaf. It is found that the PSII antenna size is larger on the abaxial side of A. thaliana leaves, presumably because chloroplasts in the spongy mesophyll are "shaded" by the palisade cells. The number of chlorophylls in PSI on the adaxial side of the A. thaliana leaf is slightly higher. The C4 plant M. x giganteus contains both mesophyll and bundle sheath cells, which have a different PSI/PSII ratio. It is shown that the time-resolved fluorescence of bundle sheath and mesophyll cells can be analysed separately. The relative number of chlorophylls, which belong to PSI (as compared to PSII) in the bundle sheath cells is at least 2.5 times higher than in mesophyll cells. FLIM is thus demonstrated to be a useful technique to study the PSI/PSII ratio and PSII antenna size in well-defined regions of plant leaves without having to isolate pigment-protein complexes. Copyright © 2016 Elsevier B.V. All rights reserved.

Thick filament length and isoform composition determine self-organized contractile units in actomyosin bundles.

PubMed

Thoresen, Todd; Lenz, Martin; Gardel, Margaret L

2013-02-05

Diverse myosin II isoforms regulate contractility of actomyosin bundles in disparate physiological processes by variations in both motor mechanochemistry and the extent to which motors are clustered into thick filaments. Although the role of mechanochemistry is well appreciated, the extent to which thick filament length regulates actomyosin contractility is unknown. Here, we study the contractility of minimal actomyosin bundles formed in vitro by mixtures of F-actin and thick filaments of nonmuscle, smooth, and skeletal muscle myosin isoforms with varied length. Diverse myosin II isoforms guide the self-organization of distinct contractile units within in vitro bundles with shortening rates similar to those of in vivo myofibrils and stress fibers. The tendency to form contractile units increases with the thick filament length, resulting in a bundle shortening rate proportional to the length of constituent myosin thick filament. We develop a model that describes our data, providing a framework in which to understand how diverse myosin II isoforms regulate the contractile behaviors of disordered actomyosin bundles found in muscle and nonmuscle cells. These experiments provide insight into physiological processes that use dynamic regulation of thick filament length, such as smooth muscle contraction. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Effects of Gingko biloba extract (EGb 761) on vascular smooth muscle cell calcification induced by β-glycerophosphate.

PubMed

Li, En-Gang; Tian, Jun; Xu, Zhong-Hua

2016-01-01

To investigate the effects of Gingko biloba extract (EGb 761) on calcification induced by β-glycerophosphate in rat aortic vascular smooth muscle cells. Rat aortic vascular smooth muscle cells were cultured with various concentrations of EGb 761 and β-glycerophosphate for 7 days. Calcium content in the cells, alkaline phosphatase activity, cell protein content, NF-κB activation, and reactive oxygen species production were assayed, respectively. The calcium depositions of vascular smooth muscle cells of the β-glycerophosphate group were significantly higher than those of the control group (p < 0.01), and were inhibited by EGb 761 in a concentration-dependent manner (p < 0.05). Data showed β-glycerophosphate induced the enhanced expression of alkaline phosphatase, up-regulated the NF-κB activity and increased reactive oxygen species production of vascular smooth muscle cells while these decreased when administrated with EGb 761(p < 0.05). EGb 761 significantly reduced deposition of calcium induced by β-glycerophosphate in rat aortic vascular smooth muscle cells. It not only reduced the deposition of calcium, but also inhibited osteogenic transdifferentiation, which may be associated with decreasing expression of alkaline phosphatase, down-regulating the NF-κB activity, and reducing reactive oxygen species production of vascular smooth muscle cells, and may have the potential to serve as a role for vascular calcification in clinical situations.

Epithelial rotation promotes the global alignment of contractile actin bundles during Drosophila egg chamber elongation

PubMed Central

Cetera, Maureen; Ramirez-San Juan, Guillermina R.; Oakes, Patrick W.; Lewellyn, Lindsay; Fairchild, Michael J.; Tanentzapf, Guy; Gardel, Margaret L.; Horne-Badovinac, Sally

2014-01-01

Tissues use numerous mechanisms to change shape during development. The Drosophila egg chamber is an organ-like structure that elongates to form an elliptical egg. During elongation the follicular epithelial cells undergo a collective migration that causes the egg chamber to rotate within its surrounding basement membrane. Rotation coincides with the formation of a “molecular corset”, in which actin bundles in the epithelium and fibrils in the basement membrane are all aligned perpendicular to the elongation axis. Here we show that rotation plays a critical role in building the actin-based component of the corset. Rotation begins shortly after egg chamber formation and requires lamellipodial protrusions at each follicle cell’s leading edge. During early stages, rotation is necessary for tissue-level actin bundle alignment, but it becomes dispensable after the basement membrane is polarized. This work highlights how collective cell migration can be used to build a polarized tissue organization for organ morphogenesis. PMID:25413675

Uncommon formation of two antiparallel sperm bundles per cyst in tenebrionid beetles (Coleoptera)

NASA Astrophysics Data System (ADS)

Dias, Glenda; Yotoko, Karla S. C.; Gomes, Luiz F.; Lino-Neto, José

2012-09-01

Several species of Tenebrionidae are stored-grain pests. Since they belong to a specious family, the systematics of these beetles is still in doubt. In insects, spermatogenesis and the spermatozoa exhibit great diversity, and are therefore commonly used in phylogenetic and taxonomic analyses. During the spermatogenetic process in these organisms, the cells originating from a single spermatogonium develop synchronically in groups referred to as cysts. At the end of this process, there is usually only one sperm bundle per cyst, with all the cells in the same orientation. This paper details the spermiogenesis of the tenebrionid beetles Tenebrio molitor, Zophobas confusa, Tribolium castaneum and Palembus dermestoides using whole mount and histological sections of the cysts. In these species, spermatogenesis is similar to that which occurs in most insects. However, during spermiogenesis, the nuclei of the spermatids migrate to two opposite regions at the periphery of the cyst, leading to the uncommon formation of two bundles of spermatozoa per cyst. This feature is possibly an apomorphy for Tenebrionidae.

Alteration of in vivo cellulose ribbon assembly by carboxymethylcellulose and other cellulose derivatives.

PubMed

Haigler, C H; White, A R; Brown, R M; Cooper, K M

1982-07-01

In vivo cellulose ribbon assembly by the Gram-negative bacterium Acetobacter xylinum can be altered by incubation in carboxymethylcellulose (CMC), a negatively charged water-soluble cellulose derivative, and also by incubation in a variety of neutral, water-soluble cellulose derivatives. In the presence of all of these substituted celluloses, normal fasciation of microfibril bundles to form the typical twisting ribbon is prevented. Alteration of ribbon assembly is most extensive in the presence of CMC, which often induces synthesis of separate, intertwining bundles of microfibrils. Freeze-etch preparations of the bacterial outer membrane suggest that particles that are thought to be associated with cellulose synthesis or extrusion may be specifically organized to mediate synthesis of microfibril bundles. These data support the previous hypothesis that the cellulose ribbon of A. xylinum is formed by a hierarchical, cell-directed, self-assembly process. The relationship of these results to the regulation of cellulose microfibril size and wall extensibility in plant cell walls is discussed.

Generation of contractile actomyosin bundles depends on mechanosensitive actin filament assembly and disassembly

PubMed Central

Tojkander, Sari; Gateva, Gergana; Husain, Amjad; Krishnan, Ramaswamy; Lappalainen, Pekka

2015-01-01

Adhesion and morphogenesis of many non-muscle cells are guided by contractile actomyosin bundles called ventral stress fibers. While it is well established that stress fibers are mechanosensitive structures, physical mechanisms by which they assemble, align, and mature have remained elusive. Here we show that arcs, which serve as precursors for ventral stress fibers, undergo lateral fusion during their centripetal flow to form thick actomyosin bundles that apply tension to focal adhesions at their ends. Importantly, this myosin II-derived force inhibits vectorial actin polymerization at focal adhesions through AMPK-mediated phosphorylation of VASP, and thereby halts stress fiber elongation and ensures their proper contractility. Stress fiber maturation additionally requires ADF/cofilin-mediated disassembly of non-contractile stress fibers, whereas contractile fibers are protected from severing. Taken together, these data reveal that myosin-derived tension precisely controls both actin filament assembly and disassembly to ensure generation and proper alignment of contractile stress fibers in migrating cells. DOI: http://dx.doi.org/10.7554/eLife.06126.001 PMID:26652273

Generation of contractile actomyosin bundles depends on mechanosensitive actin filament assembly and disassembly.

PubMed

Tojkander, Sari; Gateva, Gergana; Husain, Amjad; Krishnan, Ramaswamy; Lappalainen, Pekka

2015-12-10

Adhesion and morphogenesis of many non-muscle cells are guided by contractile actomyosin bundles called ventral stress fibers. While it is well established that stress fibers are mechanosensitive structures, physical mechanisms by which they assemble, align, and mature have remained elusive. Here we show that arcs, which serve as precursors for ventral stress fibers, undergo lateral fusion during their centripetal flow to form thick actomyosin bundles that apply tension to focal adhesions at their ends. Importantly, this myosin II-derived force inhibits vectorial actin polymerization at focal adhesions through AMPK-mediated phosphorylation of VASP, and thereby halts stress fiber elongation and ensures their proper contractility. Stress fiber maturation additionally requires ADF/cofilin-mediated disassembly of non-contractile stress fibers, whereas contractile fibers are protected from severing. Taken together, these data reveal that myosin-derived tension precisely controls both actin filament assembly and disassembly to ensure generation and proper alignment of contractile stress fibers in migrating cells.

MicroRNA regulation of endothelial homeostasis and commitment-implications for vascular regeneration strategies using stem cell therapies.

PubMed

Scott, Elizabeth; Loya, Komal; Mountford, Joanne; Milligan, Graeme; Baker, Andrew H

2013-09-01

Human embryonic (hESC) and induced pluripotent (hiPSC) stem cells have broad therapeutic potential in the treatment of a range of diseases, including those of the vascular system. Both hESCs and hiPSCs have the capacity for indefinite self-renewal, in addition to their ability to differentiate into any adult cell type. These cells could provide a potentially unlimited source of cells for transplantation and, therefore, provide novel treatments, e.g. in the production of endothelial cells for vascular regeneration. MicroRNAs are short, noncoding RNAs that act posttranscriptionally to control gene expression and thereby exert influence over a wide range of cellular processes, including maintenance of pluripotency and differentiation. Expression patterns of these small RNAs are tissue specific, and changes in microRNA levels have often been associated with disease states in humans, including vascular pathologies. Here, we review the roles of microRNAs in endothelial cell function and vascular disease, as well as their role in the differentiation of pluripotent stem cells to the vascular endothelial lineage. Furthermore, we discuss the therapeutic potential of stem cells and how knowledge and manipulation of microRNAs in stem cells may enhance their capacity for vascular regeneration. © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

Rumen Bacterial Degradation of Forage Cell Walls Investigated by Electron Microscopy

PubMed Central

Akin, Danny E.; Amos, Henry E.

1975-01-01

The association of rumen bacteria with specific leaf tissues of the forage grass Kentucky-31 tall fescue (Festuca arundinacea Schreb.) during in vitro degradation was investigated by transmission and scanning electron microscopy. Examination of degraded leaf cross-sections revealed differential rates of tissue degradation in that the cell walls of the mesophyll and pholem were degraded prior to those of the outer bundle sheath and epidermis. Rumen bacteria appeared to degrade the mesophyll, in some cases, and phloem without prior attachment to the plant cell walls. The degradation of bundle sheath and epidermal cell walls appeared to be preceded by attachment of bacteria to the plant cell wall. Ultrastructural features apparently involved in the adhesion of large cocci to plant cells were observed by transmission and scanning electron microscopy. The physical association between plant and rumen bacterial cells during degradation apparently varies with tissue types. Bacterial attachment, by extracellular features in some microorganisms, is required prior to degradation of the more resistant tissues. Images PMID:16350017

Bundle-sheath leakiness in C4 photosynthesis: a careful balancing act between CO2 concentration and assimilation.

PubMed

Kromdijk, Johannes; Ubierna, Nerea; Cousins, Asaph B; Griffiths, Howard

2014-07-01

Crop species with the C4 photosynthetic pathway are generally characterized by high productivity, especially in environmental conditions favouring photorespiration. In comparison with the ancestral C3 pathway, the biochemical and anatomical modifications of the C4 pathway allow spatial separation of primary carbon acquisition in mesophyll cells and subsequent assimilation in bundle-sheath cells. The CO2-concentrating C4 cycle has to operate in close coordination with CO2 reduction via the Calvin-Benson-Bassham (CBB) cycle in order to keep the C4 pathway energetically efficient. The gradient in CO2 concentration between bundle-sheath and mesophyll cells facilitates diffusive leakage of CO2. This rate of bundle-sheath CO2 leakage relative to the rate of phosphoenolpyruvate carboxylation (termed leakiness) has been used to probe the balance between C4 carbon acquisition and subsequent reduction as a result of environmental perturbations. When doing so, the correct choice of equations to derive leakiness from stable carbon isotope discrimination (Δ(13)C) during gas exchange is critical to avoid biased results. Leakiness responses to photon flux density, either short-term (during measurements) or long-term (during growth and development), can have important implications for C4 performance in understorey light conditions. However, recent reports show leakiness to be subject to considerable acclimation. Additionally, the recent discovery of two decarboxylating C4 cycles operating in parallel in Zea mays suggests that flexibility in the transported C4 acid and associated decarboxylase could also aid in maintaining C4/CBB balance in a changing environment. In this paper, we review improvements in methodology to estimate leakiness, synthesize reports on bundle-sheath leakiness, discuss different interpretations, and highlight areas where future research is necessary. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Choline acetyltransferase (ChAT) immunoelectron microscopy distinguishes at least three types of efferent synapses in the organ of Corti.

PubMed

Eybalin, M; Pujol, R

1987-01-01

Using anatomical criteria, the olivo-cochlear fibers ending in the organ of Corti (efferent fibers) have recently been separated into two systems: a lateral system innervating principally the inner hair cell (IHC) area and a medial system innervating mainly the outer hair cells (OHCs). Electrophysiological and biochemical experiments suggest that acetylcholine may be a neurotransmitter of these efferent fibers. However, efferent synapses that use acetylcholine as neurotransmitter have not yet been identified at the electron microscopic level. Using a pre-embedding immunoelectron microscopic technique with a monoclonal antibody against choline acetyltransferase (ChAT), we localized ChAT-immunostained fibers below both the IHCs and OHCs. In the inner spiral bundle, one type of ChAT-immunostained fibers was vesiculated and formed axo-dendritic synapses with the afferent auditory dendrites contacting the inner hair cells. A second type of ChAT-immunostained fibers seen in the inner spiral bundle was unvesiculated. Unstained vesiculated varicosities synapsing with the auditory dendrites were also seen in the inner spiral bundle. At the OHC level, ChAT immunostaining was found in nearly all the terminals synapsing with the OHCs. The finding of two types of ChAT-immunostained efferent synapses in the organ of Corti, i.e. axo-dendritic synapses in the inner spiral bundle and axo-somatic synapses with the OHCs, supports the hypothesis that both the lateral and the medial olivo-cochlear systems use acetylcholine as a neurotransmitter. The finding of numerous unstained synapses in the inner spiral bundle, and some below OHCs, together with previous data about putative cochlear neurotransmitters, suggests the possibility of additional non-cholinergic olivo-cochlear systems. It might soon appear useful to reclassify efferents according to the nature of the different neurotransmitters/co-transmitters found in the various efferent synapses of the organ of Corti.

Spatiotemporal changes in the distribution of LHFPL5 in mice cochlear hair bundles during development and in the absence of PCDH15

PubMed Central

Mahendrasingam, Shanthini; Fettiplace, Robert; Alagramam, Kumar N.; Cross, Ellen

2017-01-01

Mechanosensory transduction by vertebrate hair cells depends on a protein complex at the tips of shorter stereocilia associated with mechanoelectrical transduction channels activated by tip links in the hair bundle. In mammalian hair cells, this complex includes transmembrane channel-like protein subunit 1 (TMC1), lipoma HMGIC fusion partner-like 5 protein (LHFPL5) and protocadherin 15 (PCDH15), a lower-end component of the tip link. TMC1 interacts with LHFPL5 and PCDH15 but how the complex develops to maturity, and the relationships between these proteins, remains uncertain. Here we evaluate the spatiotemporal development of LHFPL5 distributions in mouse cochlear hair bundles by immunofluorescence and immunogold transmission electron microscopy, from postnatal day 0 (P0) through P21 in wild type and PCDH15-deficient mice. At P0, hair bundles contain many short microvilli-like processes which we term unranked stereocilia, and a subset of lengthening rows, adjacent to a kinocilium. LHFPL5 is distributed throughout the bundle, including on stereocilia tips and the kinocilium. At P3, 4-to-6 rows of ranked stereocilia are evident, total LHFPL5 expression peaks, and LHFPL5 is localised to ranked stereocilia tips of all rows and to lower shaft/ankle links. By P12, the bundle has a mature pattern with 3 ranked rows but virtually no unranked stereocilia or kinocilium; LHFPL5 expression has declined and become restricted to the tips of shorter stereocilia. Throughout development from P0, expression of LHFPL5 is greater overall on apical than basal bundles, but there is, on average, an equal amount of labelling per labelled tip. In P3 mice lacking PCDH15, LHFPL5 labelling is not at the tips but is primarily on unranked stereocilia and lower lateral links. These data show that LHFPL5 is already present in the MET apparatus at P0 but requires PCDH15 at P3 to remain there. Shaft/ankle link localisation suggests it interacts with link proteins other than PCDH15. PMID:29069081

Evidence for Apoplasmic Phloem Unloading in Developing Apple Fruit1

PubMed Central

Zhang, Ling-Yun; Peng, Yi-Ben; Pelleschi-Travier, Sandrine; Fan, Ying; Lu, Yan-Fen; Lu, Ying-Min; Gao, Xiu-Ping; Shen, Yuan-Yue; Delrot, Serge; Zhang, Da-Peng

2004-01-01

The phloem unloading pathway remains unclear in fleshy fruits accumulating a high level of soluble sugars. A structural investigation in apple fruit (Malus domestica Borkh. cv Golden Delicious) showed that the sieve element-companion cell complex of the sepal bundles feeding the fruit flesh is symplasmically isolated over fruit development. 14C-autoradiography indicated that the phloem of the sepal bundles was functional for unloading. Confocal laser scanning microscopy imaging of carboxyfluorescein unloading showed that the dye remained confined to the phloem strands of the sepal bundles from the basal to the apical region of the fruit. A 52-kD putative monosaccharide transporter was immunolocalized predominantly in the plasma membrane of both the sieve elements and parenchyma cells and its amount increased during fruit development. A 90-kD plasma membrane H+-ATPase was also localized in the plasma membrane of the sieve element-companion cell complex. Studies of [14C]sorbitol unloading suggested that an energy-driven monosaccharide transporter may be functional in phloem unloading. These data provide clear evidence for an apoplasmic phloem unloading pathway in apple fruit and give information on the structural and molecular features involved in this process. PMID:15122035

The BEACH protein LRBA is required for hair bundle maintenance in cochlear hair cells and for hearing.

PubMed

Vogl, Christian; Butola, Tanvi; Haag, Natja; Hausrat, Torben J; Leitner, Michael G; Moutschen, Michel; Lefèbvre, Philippe P; Speckmann, Carsten; Garrett, Lillian; Becker, Lore; Fuchs, Helmut; Hrabe de Angelis, Martin; Nietzsche, Sandor; Kessels, Michael M; Oliver, Dominik; Kneussel, Matthias; Kilimann, Manfred W; Strenzke, Nicola

2017-11-01

Lipopolysaccharide-responsive beige-like anchor protein (LRBA) belongs to the enigmatic class of BEACH domain-containing proteins, which have been attributed various cellular functions, typically involving intracellular protein and membrane transport processes. Here, we show that LRBA deficiency in mice leads to progressive sensorineural hearing loss. In LRBA knockout mice, inner and outer hair cell stereociliary bundles initially develop normally, but then partially degenerate during the second postnatal week. LRBA deficiency is associated with a reduced abundance of radixin and Nherf2, two adaptor proteins, which are important for the mechanical stability of the basal taper region of stereocilia. Our data suggest that due to the loss of structural integrity of the central parts of the hair bundle, the hair cell receptor potential is reduced, resulting in a loss of cochlear sensitivity and functional loss of the fraction of spiral ganglion neurons with low spontaneous firing rates. Clinical data obtained from two human patients with protein-truncating nonsense or frameshift mutations suggest that LRBA deficiency may likewise cause syndromic sensorineural hearing impairment in humans, albeit less severe than in our mouse model. © 2017 The Authors.

Role of Resident Stem Cells in Vessel Formation and Arteriosclerosis.

PubMed

Zhang, Li; Issa Bhaloo, Shirin; Chen, Ting; Zhou, Bin; Xu, Qingbo

2018-05-25

Vascular, resident stem cells are present in all 3 layers of the vessel wall; they play a role in vascular formation under physiological conditions and in remodeling in pathological situations. Throughout development and adult early life, resident stem cells participate in vessel formation through vasculogenesis and angiogenesis. In adults, the vascular stem cells are mostly quiescent in their niches but can be activated in response to injury and participate in endothelial repair and smooth muscle cell accumulation to form neointima. However, delineation of the characteristics and of the migration and differentiation behaviors of these stem cells is an area of ongoing investigation. A set of genetic mouse models for cell lineage tracing has been developed to specifically address the nature of these cells and both migration and differentiation processes during physiological angiogenesis and in vascular diseases. This review summarizes the current knowledge on resident stem cells, which has become more defined and refined in vascular biology research, thus contributing to the development of new potential therapeutic strategies to promote endothelial regeneration and ameliorate vascular disease development. © 2018 The Authors.

Human iPS cell-engineered cardiac tissue sheets with cardiomyocytes and vascular cells for cardiac regeneration

PubMed Central

Masumoto, Hidetoshi; Ikuno, Takeshi; Takeda, Masafumi; Fukushima, Hiroyuki; Marui, Akira; Katayama, Shiori; Shimizu, Tatsuya; Ikeda, Tadashi; Okano, Teruo; Sakata, Ryuzo; Yamashita, Jun K.

2014-01-01

To realize cardiac regeneration using human induced pluripotent stem cells (hiPSCs), strategies for cell preparation, tissue engineering and transplantation must be explored. Here we report a new protocol for the simultaneous induction of cardiomyocytes (CMs) and vascular cells [endothelial cells (ECs)/vascular mural cells (MCs)], and generate entirely hiPSC-engineered cardiovascular cell sheets, which showed advantageous therapeutic effects in infarcted hearts. The protocol adds to a previous differentiation protocol of CMs by using stage-specific supplementation of vascular endothelial cell growth factor for the additional induction of vascular cells. Using this cell sheet technology, we successfully generated physically integrated cardiac tissue sheets (hiPSC-CTSs). HiPSC-CTS transplantation to rat infarcted hearts significantly improved cardiac function. In addition to neovascularization, we confirmed that engrafted human cells mainly consisted of CMs in >40% of transplanted rats four weeks after transplantation. Thus, our HiPSC-CTSs show promise for cardiac regenerative therapy. PMID:25336194

Regulatory T Cell-Enriching Microparticles for Promoting Vascularized Composite Allotransplant Survival

DTIC Science & Technology

2016-10-01

AWARD NUMBER: W81XWH-15-1-0244 TITLE: Regulatory T Cell-Enriching Microparticles for Promoting Vascularized Composite Allotransplant Survival...2016 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Regulatory T Cell-Enriching Microparticles for Promoting Vascularized Composite Allotransplant Survival...observed effects these particles have on allograft survival. Key Words CTA Composite Tissue Allotransplantation VCA Vascularized Composite

Heat transfer and vascular cambium necrosis in the boles of trees during surface fires

Treesearch

M. B. Dickinson

2002-01-01

Heat-transfer and cell-survival models are used to link surface fire behavior with vascular cambium necrosis from heating by flames. Vascular cambium cell survival was predicted with a numerical model based on the kinetics of protein denaturation and parameterized with data from the literature. Cell survival was predicted for vascular cambium temperature regimes...

Circulating vascular cell adhesion molecule-1 in pre-eclampsia, gestational hypertension, and normal pregnancy: evidence of selective dysregulation of vascular cell adhesion molecule-1 homeostasis in pre-eclampsia.

PubMed

Higgins, J R; Papayianni, A; Brady, H R; Darling, M R; Walshe, J J

1998-08-01

Our purpose was to investigate circulating levels of vascular cell adhesion molecule-1 in the peripheral and uteroplacental circulations during normotensive and hypertensive pregnancies. This prospective observational study involved 2 patient groups. Group 1 consisted of 22 women with pre-eclampsia and 30 normotensive women followed up longitudinally through pregnancy and post partum. There were an additional 13 women with established gestational hypertension. Group 2 consisted of 20 women with established pre-eclampsia and 19 normotensive control subjects undergoing cesarean delivery. Plasma levels of vascular cell adhesion molecule-1 were measured in blood drawn from the antecubital vein (group 1) and from both the antecubital and uterine veins (group 2). Data were analyzed by analysis of variance. In group 1 vascular cell adhesion molecule-1 levels did not change significantly throughout normal pregnancy and post partum. Women with established pre-eclampsia had increased vascular cell adhesion molecule-1 levels compared with the normotensive pregnancy group (P = .01). Vascular cell adhesion molecule-1 levels were not elevated in women with established gestational hypertension. In group 2 significantly higher levels of vascular cell adhesion molecule-1 were detected in the uteroplacental (P < .0001) and peripheral (P < .0001) circulations of pre-eclamptic women by comparison with normotensive women. In the pre-eclamptic group there was a tendency toward higher vascular cell adhesion molecule-1 levels in the peripheral circulation than in the uteroplacental circulation (P = .06). In contrast to vascular cell adhesion molecule-1, circulating levels of E-selectin and intercellular adhesion molecule-1, other major leukocyte adhesion molecules expressed by the endothelium, were not different in pre-eclamptic and normotensive pregnancies. Established pre-eclampsia is characterized by selective dysregulation of vascular cell adhesion molecule-1 homeostasis. This event is not an early preclinical feature of pre-eclampsia, does not persist post partum, is not a feature of nonproteinuric gestational hypertension, and is not observed with other major leukocyte adhesion molecules. Induction of vascular cell adhesion molecule-1 expression in pre-eclampsia may contribute to leukocyte-mediated tissue injury in this condition or may reflect perturbation of other, previously unrecognized, functions of this molecule in pregnancy.

Crystal structure of bacterial cell-surface alginate-binding protein with an M75 peptidase motif

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maruyama, Yukie; Ochiai, Akihito; Mikami, Bunzo

Research highlights: {yields} Bacterial alginate-binding Algp7 is similar to component EfeO of Fe{sup 2+} transporter. {yields} We determined the crystal structure of Algp7 with a metal-binding motif. {yields} Algp7 consists of two helical bundles formed through duplication of a single bundle. {yields} A deep cleft involved in alginate binding locates around the metal-binding site. {yields} Algp7 may function as a Fe{sup 2+}-chelated alginate-binding protein. -- Abstract: A gram-negative Sphingomonas sp. A1 directly incorporates alginate polysaccharide into the cytoplasm via the cell-surface pit and ABC transporter. A cell-surface alginate-binding protein, Algp7, functions as a concentrator of the polysaccharide in the pit.more » Based on the primary structure and genetic organization in the bacterial genome, Algp7 was found to be homologous to an M75 peptidase motif-containing EfeO, a component of a ferrous ion transporter. Despite the presence of an M75 peptidase motif with high similarity, the Algp7 protein purified from recombinant Escherichia coli cells was inert on insulin B chain and N-benzoyl-Phe-Val-Arg-p-nitroanilide, both of which are substrates for a typical M75 peptidase, imelysin, from Pseudomonas aeruginosa. The X-ray crystallographic structure of Algp7 was determined at 2.10 A resolution by single-wavelength anomalous diffraction. Although a metal-binding motif, HxxE, conserved in zinc ion-dependent M75 peptidases is also found in Algp7, the crystal structure of Algp7 contains no metal even at the motif. The protein consists of two structurally similar up-and-down helical bundles as the basic scaffold. A deep cleft between the bundles is sufficiently large to accommodate macromolecules such as alginate polysaccharide. This is the first structural report on a bacterial cell-surface alginate-binding protein with an M75 peptidase motif.« less

Vaccination with vascular progenitor cells derived from induced pluripotent stem cells elicits antitumor immunity targeting vascular and tumor cells.

PubMed

Koido, Shigeo; Ito, Masaki; Sagawa, Yukiko; Okamoto, Masato; Hayashi, Kazumi; Nagasaki, Eijiro; Kan, Shin; Komita, Hideo; Kamata, Yuko; Homma, Sadamu

2014-05-01

Vaccination of BALB/c mice with dendritic cells (DCs) loaded with the lysate of induced vascular progenitor (iVP) cells derived from murine-induced pluripotent stem (iPS) cells significantly suppressed the tumor of CMS-4 fibrosarcomas and prolonged the survival of CMS-4-inoculated mice. This prophylactic antitumor activity was more potent than that of immunization with DCs loaded with iPS cells or CMS-4 tumor cells. Tumors developed slowly in mice vaccinated with DCs loaded with iVP cells (DC/iVP) and exhibited a limited vascular bed. Immunohistochemistry and a tomato-lectin perfusion study demonstrated that the tumors that developed in the iVP-immunized mice showed a marked decrease in tumor vasculature. Immunization with DC/iVP induced a potent suppressive effect on vascular-rich CMS-4 tumors, a weaker effect on BNL tumors with moderate vasculature, and nearly no effect on C26 tumors with poor vasculature. Treatment of DC/iVP-immunized mice with a monoclonal antibody against CD4 or CD8, but not anti-asialo GM1, inhibited the antitumor activity. CD8(+) T cells from DC/iVP-vaccinated mice showed significant cytotoxic activity against murine endothelial cells and CMS-4 cells, whereas CD8(+) T cells from DC/iPS-vaccinated mice did not. DNA microarray analysis showed that the products of 29 vasculature-associated genes shared between genes upregulated by differentiation from iPS cells into iVP cells and genes shared by iVP cells and isolated Flk-1(+) vascular cells in CMS-4 tumor tissue might be possible targets in the immune response. These results suggest that iVP cells from iPS cells could be used as a cancer vaccine targeting tumor vascular cells and tumor cells.

Cholangiocytes and blood supply.

PubMed

Gaudio, Eugenio; Franchitto, Antonio; Pannarale, Luigi; Carpino, Guido; Alpini, Gianfranco; Francis, Heather; Glaser, Shannon; Alvaro, Domenico; Onori, Paolo

2006-06-14

The microvascular supply of the biliary tree, the peribiliary plexus (PBP), stems from the hepatic artery branches and flows into the hepatic sinusoids. A detailed three-dimensional study of the PBP has been performed by using the Scanning Electron Microscopy vascular corrosion casts (SEMvcc) technique. Considering that the PBP plays a fundamental role in supporting the secretory and absorptive functions of the biliary epithelium, their organization in either normalcy and pathology is explored. The normal liver shows the PBP arranged around extra- and intrahepatic biliary tree. In the small portal tract PBP was characterized by a single layer of capillaries which progressively continued with the extrahepatic PBP where it showed a more complex vascular network. After common duct ligation (BDL), progressive modifications of bile duct and PBP proliferation are observed. The PBP presents a three-dimensional network arranged around many bile ducts and appears as bundles of vessels, composed by capillaries of homogeneous diameter with a typical round mesh structure. The PBP network is easily distinguishable from the sinusoidal network which appears normal. Considering the enormous extension of the PBP during BDL, the possible role played by the Vascular Endothelial Growth Factor (VEGF) is evaluated. VEGF-A, VEGF-C and their related receptors appeared highly immunopositive in proliferating cholangiocytes of BDL rats. The administration of anti-VEGF-A or anti-VEGF-C antibodies to BDL rats as well as hepatic artery ligation induced a reduced bile duct mass. The administration of rVEGF-A to BDL hepatic artery ligated rats prevented the decrease of cholangiocyte proliferation and VEGF-A expression as compared to BDL control rats. These data suggest the role of arterial blood supply of the biliary tree in conditions of cholangiocyte proliferation, such as it occurs during chronic cholestasis. On the other hand, the role played by VEGF as a tool of cross-talk between cholangiocytes and PBP endothelial cells suggests that manipulation of VEGF release and function could represent a therapeutic strategy for human pathological conditions characterized by damage of hepatic artery or the biliary tree.

OsNIP3;1, a rice boric acid channel, regulates boron distribution and is essential for growth under boron-deficient conditions.

PubMed

Hanaoka, Hideki; Uraguchi, Shimpei; Takano, Junpei; Tanaka, Mayuki; Fujiwara, Toru

2014-06-01

Boron is an essential micronutrient for higher plants. Boron deficiency is an important agricultural issue because it results in loss of yield quality and/or quantity in cereals and other crops. To understand boron transport mechanisms in cereals, we characterized OsNIP3;1, a member of the major intrinsic protein family in rice (Oryza sativa L.), because OsNIP3;1 is the most similar rice gene to the Arabidopsis thaliana boric acid channel genes AtNIP5;1 and AtNIP6;1. Yeast cells expressing OsNIP3;1 imported more boric acid than control cells. GFP-tagged OsNIP3;1 expressed in tobacco BY2 cells was localized to the plasma membrane. The accumulation of OsNIP3;1 transcript increased fivefold in roots within 6 h of the onset of boron starvation, but not in shoots. Promoter-GUS analysis suggested that OsNIP3;1 is expressed mainly in exodermal cells and steles in roots, as well as in cells around the vascular bundles in leaf sheaths and pericycle cells around the xylem in leaf blades. The growth of OsNIP3;1 RNAi plants was impaired under boron limitation. These results indicate that OsNIP3;1 functions as a boric acid channel, and is required for acclimation to boron limitation. Boron distribution among shoot tissues was altered in OsNIP3;1 knockdown plants, especially under boron-deficient conditions. This result demonstrates that OsNIP3;1 regulates boron distribution among shoot tissues, and that the correct boron distribution is crucial for plant growth. © 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.

Adipose-Derived Stromal Vascular Fraction Differentially Expands Breast Progenitors in Tissue Adjacent to Tumors Compared to Healthy Breast Tissue

PubMed Central

Chatterjee, Sumanta; Laliberte, Mike; Blelloch, Sarah; Ratanshi, Imran; Safneck, Janice; Buchel, Ed

2015-01-01

Background: Autologous fat grafts supplemented with adipose-derived stromal vascular fraction are used in reconstructive and cosmetic breast procedures. Stromal vascular fraction contains adipose-derived stem cells that are thought to encourage wound healing, tissue regeneration, and graft retention. Although use of stromal vascular fraction has provided exciting perspectives for aesthetic procedures, no studies have yet been conducted to determine whether its cells contribute to breast tissue regeneration. The authors examined the effect of these cells on the expansion of human breast epithelial progenitors. Methods: From patients undergoing reconstructive breast surgery following mastectomies, abdominal fat, matching tissue adjacent to breast tumors, and the contralateral non–tumor-containing breast tissue were obtained. Ex vivo co-cultures using breast epithelial cells and the stromal vascular fraction cells were used to study the expansion potential of breast progenitors. Breast reduction samples were collected as a source of healthy breast cells. Results: The authors observed that progenitors present in healthy breast tissue or contralateral non–tumor-containing breast tissue showed significant and robust expansion in the presence of stromal vascular fraction (5.2- and 4.8-fold, respectively). Whereas the healthy progenitors expanded up to 3-fold without the stromal vascular fraction cells, the expansion of tissue adjacent to breast tumor progenitors required the presence of stromal vascular fraction cells, leading to a 7-fold expansion, which was significantly higher than the expansion of healthy progenitors with stromal vascular fraction. Conclusions: The use of stromal vascular fraction might be more beneficial to reconstructive operations following mastectomies compared with cosmetic corrections of the healthy breast. Future studies are required to examine the potential risk factors associated with its use. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, V. PMID:26090768

Differentiation of vascular smooth muscle cells from local precursors during embryonic and adult arteriogenesis requires Notch signaling

PubMed Central

Chang, Linda; Noseda, Michela; Higginson, Michelle; Ly, Michelle; Patenaude, Alexandre; Fuller, Megan; Kyle, Alastair H.; Minchinton, Andrew I.; Puri, Mira C.; Dumont, Daniel J.; Karsan, Aly

2012-01-01

Vascular smooth muscle cells (VSMC) have been suggested to arise from various developmental sources during embryogenesis, depending on the vascular bed. However, evidence also points to a common subpopulation of vascular progenitor cells predisposed to VSMC fate in the embryo. In the present study, we use binary transgenic reporter mice to identify a Tie1+CD31dimvascular endothelial (VE)-cadherin−CD45− precursor that gives rise to VSMC in vivo in all vascular beds examined. This precursor does not represent a mature endothelial cell, because a VE-cadherin promoter-driven reporter shows no expression in VSMC during murine development. Blockade of Notch signaling in the Tie1+ precursor cell, but not the VE-cadherin+ endothelial cell, decreases VSMC investment of developing arteries, leading to localized hemorrhage in the embryo at the time of vascular maturation. However, Notch signaling is not required in the Tie1+ precursor after establishment of a stable artery. Thus, Notch activity is required in the differentiation of a Tie1+ local precursor to VSMC in a spatiotemporal fashion across all vascular beds. PMID:22509029

Human adipose-derived stem cells promote vascularization of collagen-based scaffolds transplanted into nude mice

PubMed Central

Cherubino, Mario; Valdatta, Luigi; Balzaretti, Riccardo; Pellegatta, Igor; Rossi, Federica; Protasoni, Marina; Tedeschi, Alessandra; Accolla, Roberto S; Bernardini, Giovanni; Gornati, Rosalba

2016-01-01

Aim: After in vivo implantation of cell-loaded devices, only the cells close to the capillaries can obtain nutrients to maintain their functions. It is known that factors secreted by stem cells, rather than stem cells themselves, are fundamental to guarantee new vascularization in the area of implant. Materials & methods: To investigate this possibility, we have grafted mice with Bilayer and Flowable Integra® scaffolds, loaded or not with human adipose-derived stem cells. Results: Our results support the therapeutic potential of human adipose-derived stem cells to induce new vascular networks of engineered organs and tissues. Conclusion: This finding suggests that our approach can help to form new vascular networks that allow sufficient vascularization of engineered organs and tissues in cases of difficult wound healing due to ischemic conditions. PMID:26965659

Vascular Regeneration in a Basal Chordate Is Due to the Presence of Immobile, Bi-Functional Cells

PubMed Central

Braden, Brian P.; Taketa, Daryl A.; Pierce, James D.; Kassmer, Susannah; Lewis, Daniel D.; De Tomaso, Anthony W.

2014-01-01

The source of tissue turnover during homeostasis or following injury is usually due to proliferation of a small number of resident, lineage-restricted stem cells that have the ability to amplify and differentiate into mature cell types. We are studying vascular regeneration in a chordate model organism, Botryllus schlosseri, and have previously found that following surgical ablation of the extracorporeal vasculature, new tissue will regenerate in a VEGF-dependent process within 48 hrs. Here we use a novel vascular cell lineage tracing methodology to assess regeneration in parabiosed individuals and demonstrate that the source of regenerated vasculature is due to the proliferation of pre-existing vascular resident cells and not a mobile progenitor. We also show that these cells are bi-potential, and can reversibly adopt two fates, that of the newly forming vessels or the differentiated vascular tissue at the terminus of the vasculature, known as ampullae. In addition, we show that pre-existing vascular resident cells differentially express progenitor and differentiated cell markers including the Botryllus homologs of CD133, VEGFR-2, and Cadherin during the regenerative process. PMID:24736432

Vascular Cell Induction Culture System Using Arabidopsis Leaves (VISUAL) Reveals the Sequential Differentiation of Sieve Element-Like Cells.

PubMed

Kondo, Yuki; Nurani, Alif Meem; Saito, Chieko; Ichihashi, Yasunori; Saito, Masato; Yamazaki, Kyoko; Mitsuda, Nobutaka; Ohme-Takagi, Masaru; Fukuda, Hiroo

2016-06-01

Cell differentiation is a complex process involving multiple steps, from initial cell fate specification to final differentiation. Procambial/cambial cells, which act as vascular stem cells, differentiate into both xylem and phloem cells during vascular development. Recent studies have identified regulatory cascades for xylem differentiation. However, the molecular mechanism underlying phloem differentiation is largely unexplored due to technical challenges. Here, we established an ectopic induction system for phloem differentiation named Vascular Cell Induction Culture System Using Arabidopsis Leaves (VISUAL). Our results verified similarities between VISUAL-induced Arabidopsis thaliana phloem cells and in vivo sieve elements. We performed network analysis using transcriptome data with VISUAL to dissect the processes underlying phloem differentiation, eventually identifying a factor involved in the regulation of the master transcription factor gene APL Thus, our culture system opens up new avenues not only for genetic studies of phloem differentiation, but also for future investigations of multidirectional differentiation from vascular stem cells. © 2016 American Society of Plant Biologists. All rights reserved.

Piezo- and Flexoelectric Membrane Materials Underlie Fast Biological Motors in the Ear

PubMed Central

Breneman, Kathryn D.; Rabbitt, Richard D.

2010-01-01

The mammalian inner ear is remarkably sensitive to quiet sounds, exhibits over 100dB dynamic range, and has the exquisite ability to discriminate closely spaced tones even in the presence of noise. This performance is achieved, in part, through active mechanical amplification of vibrations by sensory hair cells within the inner ear. All hair cells are endowed with a bundle of motile microvilli, stereocilia, located at the apical end of the cell, and the more specialized outer hair cells (OHC’s) are also endowed with somatic electromotility responsible for changes in cell length in response to perturbations in membrane potential. Both hair bundle and somatic motors are known to feed energy into the mechanical vibrations in the inner ear. The biophysical origin and relative significance of the motors remains a subject of intense research. Several biological motors have been identified in hair cells that might underlie the motor(s), including a cousin of the classical ATP driven actin-myosin motor found in skeletal muscle. Hydrolysis of ATP, however, is much too slow to be viable at audio frequencies on a cycle-by-cycle basis. Heuristically, the OHC somatic motor behaves as if the OHC lateral wall membrane were a piezoelectric material and the hair bundle motor behaves as if the plasma membrane were a flexoelectric material. We propose these observations from a continuum materials perspective are literally true. To examine this idea, we formulated mathematical models of the OHC lateral wall “piezoelectric” motor and the more ubiquitous “flexoelectric” hair bundle motor. Plausible biophysical mechanisms underlying piezo- and flexoelectricity were established. Model predictions were compared extensively to the available data. The models were then applied to study the power conversion efficiency of the motors. Results show that the material properties of the complex membranes in hair cells provide them with the ability to convert electrical power available in the inner ear cochlea into useful mechanical amplification of sound induced vibrations at auditory frequencies. We also examined how hair cell amplification might be controlled by the brain through efferent synaptic contacts on hair cells and found a simple mechanism to tune hearing to signals of interest to the listener by electrical control of these motors. PMID:21188296

Calcium Deficiency Triggers Phloem Remobilization of Cadmium in a Hyperaccumulating Species1

PubMed Central

Tian, Shengke; Xie, Ruohan; Wang, Haixin; Hu, Yan; Ge, Jun; Liao, Xingcheng; Gao, Xiaoyu; Brown, Patrick; Lin, Xianyong; Lu, Lingli

2016-01-01

Understanding cadmium (Cd) accumulation in plants is critical for the development of plant-based strategies for soil remediation and crop safety. Sedum alfredii is a nonbrassica plant species known to hyperaccumulate Cd. The characteristics of Cd uptake, distribution, and retranslocation affected by the Ca status were investigated at cellular levels in S. alfredii. Low Ca supply significantly increased Cd contents in shoots of S. alfredii, particularly in the young leaves. Micro x-ray fluorescence images confirmed that sequestration of Cd was greatly enhanced in the young leaves under Ca deficiency stress, with a significant amount of Cd localized in mesophyll cells, compared to the young leaves supplied with high Ca levels. Cd influx into protoplasts isolated from young leaves was significantly inhibited by the addition of Ca channel inhibitors, but not by pre-exposure to Ca deficiency. In stems, the Cd signal in vascular systems under low Ca levels was 10-fold higher than in those treated with higher Ca levels. A detailed investigation of vascular bundles revealed that an extremely high Cd signal induced by low Ca supply occurred in the phloem tissues, but not in the xylem tissues. Transfer of Cd pretreated plants to nutrient solutions at different Ca levels confirmed that a much higher amount of Cd was reallocated to the new growth tissues under low Ca stress compared to plants supplied with sufficient Ca. These results suggest that Ca deficiency triggered a highly efficient phloem remobilization of Cd in S. alfredii and subsequently enhanced Cd accumulation in its young leaves. PMID:27789737

Ultrastructure of myopericytoma: a continuum of transitional phenotypes of myopericytes.

PubMed

Díaz-Flores, L; Gutiérrez, R; García, M P; Díaz-Flores, L; Valladares, F; Madrid, J F

2012-05-01

The authors report the ultrastructural characteristics of myopericytoma, a recently described variant of perivascular (pericytic) tumors, mainly with regard to their myopericytic cells and vessels. Myopericytes range between pericytes and vascular smooth muscle cells (SMCs) in a morphologic continuum. The principal findings of the intermediate phenotypes are (1) elongated or annular morphology with processes of varying length and thickness (usually long and thin); (2) a continuous, irregularly thickened and zonally duplicated basement membrane; (3) heterocellular "peg and socket" junctions with neighboring endothelial cells, and scarce specialized junctions between myopericytes; (4) numerous micropinocytotic vesicles, whether continuous or forming focal rows; (5) abundant thin microfilaments, grouped in bundles with dense bodies and adhesion plaques; (6) poorly developed synthetic system (RER and Golgi); (7) pseudointracellular bodies formed by invagination of basement and plasma membranes, with numerous endocytic vesicles; and (8) zones of cytoplasmic rarefaction near micropinocytotic vesicles and intracellular organelles. The ultrastructure of myopericytes therefore makes it possible to distinguish them from pericytes, SMCs, and fibroblast/myofibroblasts, which is useful for myopericytoma diagnosis. The main pattern of the vessels, with perivascular concentric and multilayered growth of myopericytes (a thick wall in contrast to a small lumen) and lack of elastic material, also supports an intermediate form between pericytic and muscular microvasculature. The presence of myopericytes more similar to SMCs and of hemangiopericytoma-like vessels concurs with transitional forms with angioleyomyoma and true hemangiopericytoma, histogenetically representing a morphologic continuum for the perivascular tumors.

Characterization and gene cloning of the rice (Oryza sativa L.) dwarf and narrow-leaf mutant dnl3.

PubMed

Shi, L; Wei, X J; Adedze, Y M N; Sheng, Z H; Tang, S Q; Hu, P S; Wang, J L

2016-09-16

The dwarf and narrow-leaf rice (Oryza sativa L.) mutant dnl3 was isolated from the Japonica cultivar Zhonghua 11 (wild-type). dnl3 exhibited pleiotropic developmental defects. The narrow-leaf phenotype resulted from a marked reduction in the number of vascular bundles, while the dwarf stature was caused by the formation of foreshortened internodes and a reduced number of parenchyma cells. The suggestion that cell division is impaired in the mutant was consistent with the transcriptional behavior of various genes associated with cell division. The mutant was less responsive to exogenously supplied gibberellic acid than the wild-type, and profiling the transcription of genes involved in gibberellin synthesis and response revealed that a lesion in the mutant affected gibberellin signal transduction. The dnl3 phenotype was inherited as a single-dominant gene, mapping within a 19.1-kb region of chromosome 12, which was found to harbor three open reading frames. Resequencing the open reading frames revealed that the mutant carried an allele at one of the three genes that differed from the wild-type sequence by 2-bp deletions; this gene encoded a cellulose synthase-like D4 (CSLD4) protein. Therefore, OsCSLD4 is a candidate gene for DNL3. DNL3 was expressed in all of the rice organs tested at the heading stage, particularly in the leaves, roots, and culms. These results suggest that DNL3 plays important roles in rice leaf morphogenesis and vegetative development.

[The dynamics of calcium distribution in stigma and style of lettuce (Lactuca sativa L.) before and after pollination].

PubMed

Qiu, Yi Lan; Liu, Ru Shi; Xie, Chao Tian; Yang, Yan Hong; Gu, Li; Tian, Hui Qiao

2005-08-01

Potassium antimonite was used to deposit calcium in the stigma and style of lettuce (Lactuca sativa L.) before and after pollination. The stigma of lettuce is two splits. Abundant calcium granules are displayed in the wall of papillae on the receptive surface of stigma before and after pollination, which may facilitate pollen germination. However, a few calcium granules in the wall of epidermis cell on no-receptive surface. Calcium distribution in style presents a gradient in transmitting tissue and parenchyma cells from the top to the base of the style before pollination. After pollination, calcium in transmitting tissue distinctly increased and its gradient distribution became more evident. Pollen tubes grow in the intercellular gaps of transmitting tissue. When pollen tubes grew into transmitting tissue, calcium granules in parenchyma around transmitting tissue decreased, suggesting a calcium movement was controlled by pollen tubes. The calcium gradient distribution also appeared in the trachea of vascular bundle of style. In general, calcium in style displays a feature of time-special distribution: transmitting tissue doesn't need much more calcium that is only stored in the parenchyma before pollination. However, calcium in parenchyma cells may be transported to transmitting tissue and make the latter contain more calcium to form an evident calcium gradient and meet the requirement of pollen tubes directionally growing after pollination. This is the second sample of calcium gradient existing in style, which was found by using potassium antimonite method.

Distribution of Silicified Microstructures, Regulation of Cinnamyl Alcohol Dehydrogenase and Lodging Resistance in Silicon and Paclobutrazol Mediated Oryza sativa

PubMed Central

Dorairaj, Deivaseeno; Ismail, Mohd Razi

2017-01-01

Lodging is a phenomenon that affects most of the cereal crops including rice, Oryza sativa. This is due to the fragile nature of herbaceous plants whose stems are non-woody, thus affecting its ability to grow upright. Silicon (Si), a beneficial nutrient is often used to toughen and protect plants from biotic and abiotic stresses. Deposition of Si in plant tissues enhances the rigidity and stiffness of the plant as a whole. Silicified cells provide the much needed strength to the culm to resist breaking. Lignin plays important roles in cell wall structural integrity, stem strength, transport, mechanical support, and plant pathogen defense. The aim of this study is to resolve effects of Si on formation of microstructure and regulation of cinnamyl alcohol dehydrogenase (CAD), a key gene responsible for lignin biosynthesis. Besides evaluating silicon, paclobutrazol (PBZ) a plant growth retartdant that reduces internode elongation is also incorporated in this study. Hardness, brittleness and stiffness were improved in presence of silicon thus reducing lodging. Scanning electron micrographs with the aid of energy dispersive x-ray (EDX) was used to map silicon distribution. Presence of trichomes, silica cells, and silica bodies were detected in silicon treated plants. Transcripts of CAD gene was also upregulated in these plants. Besides, phloroglucinol staining showed presence of lignified vascular bundles and sclerenchyma band. In conclusion, silicon treated rice plants showed an increase in lignin content, silicon content, and formation of silicified microstructures. PMID:28747889

Platelets regulate lymphatic vascular development through CLEC-2-SLP-76 signaling.

PubMed

Bertozzi, Cara C; Schmaier, Alec A; Mericko, Patricia; Hess, Paul R; Zou, Zhiying; Chen, Mei; Chen, Chiu-Yu; Xu, Bin; Lu, Min-min; Zhou, Diane; Sebzda, Eric; Santore, Matthew T; Merianos, Demetri J; Stadtfeld, Matthias; Flake, Alan W; Graf, Thomas; Skoda, Radek; Maltzman, Jonathan S; Koretzky, Gary A; Kahn, Mark L

2010-07-29

Although platelets appear by embryonic day 10.5 in the developing mouse, an embryonic role for these cells has not been identified. The SYK-SLP-76 signaling pathway is required in blood cells to regulate embryonic blood-lymphatic vascular separation, but the cell type and molecular mechanism underlying this regulatory pathway are not known. In the present study we demonstrate that platelets regulate lymphatic vascular development by directly interacting with lymphatic endothelial cells through C-type lectin-like receptor 2 (CLEC-2) receptors. PODOPLANIN (PDPN), a transmembrane protein expressed on the surface of lymphatic endothelial cells, is required in nonhematopoietic cells for blood-lymphatic separation. Genetic loss of the PDPN receptor CLEC-2 ablates PDPN binding by platelets and confers embryonic lymphatic vascular defects like those seen in animals lacking PDPN or SLP-76. Platelet factor 4-Cre-mediated deletion of Slp-76 is sufficient to confer lymphatic vascular defects, identifying platelets as the cell type in which SLP-76 signaling is required to regulate lymphatic vascular development. Consistent with these genetic findings, we observe SLP-76-dependent platelet aggregate formation on the surface of lymphatic endothelial cells in vivo and ex vivo. These studies identify a nonhemostatic pathway in which platelet CLEC-2 receptors bind lymphatic endothelial PDPN and activate SLP-76 signaling to regulate embryonic vascular development.

Illumina microRNA profiles reveal the involvement of miR397a in Citrus adaptation to long-term boron toxicity via modulating secondary cell-wall biosynthesis.

PubMed

Huang, Jing-Hao; Qi, Yi-Ping; Wen, Shou-Xing; Guo, Peng; Chen, Xiao-Min; Chen, Li-Song

2016-03-10

The mechanisms underlying tolerance to B-toxicity in plants are still controversial. Our previous studies indicated that B-toxicity is mainly limited to leaves in Citrus and that alternations of cell-wall structure in vascular bundles are involved in tolerance to B-toxicity. Here, miRNAs and their expression patterns were first identified in B-treated Citrus sinensis (tolerant) and C. grandis (intolerant) leaves via high-throughput sequencing. Candidate miRNAs were then verified with molecular and anatomical approaches. The results showed that 51 miRNAs in C. grandis and 20 miRNAs in C. sinensis were differentially expressed after B-toxic treatment. MiR395a and miR397a were the most significantly up-regulated miRNAs in B-toxic C. grandis leaves, but both were down-regulated in B-toxic C. sinensis leaves. Four auxin response factor genes and two laccase (LAC) genes were confirmed through 5'-RACE to be real targets of miR160a and miR397a, respectively. Up-regulation of LAC4 resulted in secondary deposition of cell-wall polysaccharides in vessel elements of C. sinensis, whereas down-regulation of both LAC17 and LAC4, led to poorly developed vessel elements in C. grandis. Our findings demonstrated that miR397a plays a pivotal role in woody Citrus tolerance to B-toxicity by targeting LAC17 and LAC4, both of which are responsible for secondary cell-wall synthesis.

Illumina microRNA profiles reveal the involvement of miR397a in Citrus adaptation to long-term boron toxicity via modulating secondary cell-wall biosynthesis

PubMed Central

Huang, Jing-Hao; Qi, Yi-Ping; Wen, Shou-Xing; Guo, Peng; Chen, Xiao-Min; Chen, Li-Song

2016-01-01

The mechanisms underlying tolerance to B-toxicity in plants are still controversial. Our previous studies indicated that B-toxicity is mainly limited to leaves in Citrus and that alternations of cell-wall structure in vascular bundles are involved in tolerance to B-toxicity. Here, miRNAs and their expression patterns were first identified in B-treated Citrus sinensis (tolerant) and C. grandis (intolerant) leaves via high-throughput sequencing. Candidate miRNAs were then verified with molecular and anatomical approaches. The results showed that 51 miRNAs in C. grandis and 20 miRNAs in C. sinensis were differentially expressed after B-toxic treatment. MiR395a and miR397a were the most significantly up-regulated miRNAs in B-toxic C. grandis leaves, but both were down-regulated in B-toxic C. sinensis leaves. Four auxin response factor genes and two laccase (LAC) genes were confirmed through 5′-RACE to be real targets of miR160a and miR397a, respectively. Up-regulation of LAC4 resulted in secondary deposition of cell-wall polysaccharides in vessel elements of C. sinensis, whereas down-regulation of both LAC17 and LAC4, led to poorly developed vessel elements in C. grandis. Our findings demonstrated that miR397a plays a pivotal role in woody Citrus tolerance to B-toxicity by targeting LAC17 and LAC4, both of which are responsible for secondary cell-wall synthesis. PMID:26962011

Electrostatic interaction between stereocilia: II. Influence on the mechanical properties of the hair bundle.

PubMed

Dolgobrodov, S G; Lukashkin, A N; Russell, I J

2000-12-01

This paper is based on our model [Dolgobrodov et al., 2000. Hear. Res., submitted for publication] in which we examine the significance of the polyanionic surface layers of stereocilia for electrostatic interaction between them. We analyse how electrostatic forces modify the mechanical properties of the sensory hair bundle. Different charge distribution profiles within the glycocalyx are considered. When modelling a typical experiment on bundle stiffness measurements, applying an external force to the tallest row of stereocilia shows that the asymptotic stiffness of the hair bundle for negative displacements is always larger than the asymptotic stiffness for positive displacements. This increase in stiffness is monotonic for even charge distribution and shows local minima when the negative charge is concentrated in a thinner layer within the cell coat. The minima can also originate from the co-operative effect of electrostatic repulsion and inter-ciliary links with non-linear mechanical properties. Existing experimental observations are compared with the predictions of the model. We conclude that the forces of electrostatic interaction between stereocilia may influence the mechanical properties of the hair bundle and, being strongly non-linear, contribute to the non-linear phenomena, which have been recorded from the auditory periphery.

Cell Therapy Applications for Retinal Vascular Diseases: Diabetic Retinopathy and Retinal Vein Occlusion.

PubMed

Park, Susanna S

2016-04-01

Retinal vascular conditions, such as diabetic retinopathy and retinal vein occlusion, remain leading causes of vision loss. No therapy exists to restore vision loss resulting from retinal ischemia and associated retinal degeneration. Tissue regeneration is possible with cell therapy. The goal would be to restore or replace the damaged retinal vasculature and the retinal neurons that are damaged and/or degenerating from the hypoxic insult. Currently, various adult cell therapies have been explored as potential treatment. They include mesenchymal stem cells, vascular precursor cells (i.e., CD34+ cells, hematopoietic cells or endothelial progenitor cells), and adipose stromal cells. Preclinical studies show that all these cells have a paracrine trophic effect on damaged ischemic tissue, leading to tissue preservation. Endothelial progenitor cells and adipose stromal cells integrate into the damaged retinal vascular wall in preclinical models of diabetic retinopathy and ischemia-reperfusion injury. Mesenchymal stem cells do not integrate as readily but appear to have a primary paracrine trophic effect. Early phase clinical trials have been initiated and ongoing using mesenchymal stem cells or autologous bone marrow CD34+ cells injected intravitreally as potential therapy for diabetic retinopathy or retinal vein occlusion. Adipose stromal cells or pluripotent stem cells differentiated into endothelial colony-forming cells have been explored in preclinical studies and show promise as possible therapies for retinal vascular disorders. The relative safety or efficacy of these various cell therapies for treating retinal vascular disorders have yet to be determined.

Histological study of the influence of plasma rich in growth factors (PRGF) on the healing of divided Achilles tendons in sheep.

PubMed

Fernández-Sarmiento, J Andrés; Domínguez, Juan M; Granados, María M; Morgaz, Juan; Navarrete, Rocío; Carrillo, José M; Gómez-Villamandos, Rafael J; Muñoz-Rascón, Pilar; Martín de Las Mulas, Juana; Millán, Yolanda; García-Balletbó, Montserrat; Cugat, Ramón

2013-02-06

The use of plasma rich in growth factors (PRGF) has been proposed to improve the healing of Achilles tendon injuries, but there is debate about the effectiveness of this therapy. The objective of the present study was to evaluate the histological effects of PRGF, which is a type of leukocyte-poor platelet-rich plasma, on tendon healing. The Achilles tendons of twenty-eight sheep were divided surgically. The animals were randomly divided into four groups of seven animals each. The repaired tendons in two groups received an infiltration of PRGF intraoperatively and every week for the following three weeks under ultrasound guidance. The tendons in the other two groups received injections with saline solution. The animals in one PRGF group and one saline solution group were killed at four weeks, and the animals in the remaining two groups were killed at eight weeks. The Achilles tendons were examined histologically, and the morphometry of fibroblast nuclei was calculated. The fibroblast nuclei of the PRGF-treated tendons were more elongated and more parallel to the tendon axis than the fibroblast nuclei of the tendons in the saline solution group at eight weeks. PRGF-treated tendons showed more packed and better oriented collagen bundles at both four and eight weeks. In addition to increased maturation of the collagen structure, fibroblast density was significantly lower in PRGF-infiltrated tendons. PRGF-treated tendons exhibited faster vascular regression than tendons in the control groups, as demonstrated by a lower vascular density at eight weeks. PRGF was associated with histological changes consistent with an accelerated early healing process in repaired Achilles tendons in sheep after experimental surgical disruption. PRGF-treated tendons showed improvements in the morphometric features of fibroblast nuclei, suggesting a more advanced stage of healing. At eight weeks, histological examination revealed more mature organization of collagen bundles, lower vascular densities, and decreased fibroblast densities in PRGF-treated tendons than in tendons infiltrated with saline solution. These findings were consistent with a more advanced stage of the healing process. Based on the findings in this animal model, PRGF infiltration may improve the early healing process of surgically repaired Achilles tendons.

Phase slips in oscillatory hair bundles.

PubMed

Roongthumskul, Yuttana; Shlomovitz, Roie; Bruinsma, Robijn; Bozovic, Dolores

2013-04-05

Hair cells of the inner ear contain an active amplifier that allows them to detect extremely weak signals. As one of the manifestations of an active process, spontaneous oscillations arise in fluid immersed hair bundles of in vitro preparations of selected auditory and vestibular organs. We measure the phase-locking dynamics of oscillatory bundles exposed to low-amplitude sinusoidal signals, a transition that can be described by a saddle-node bifurcation on an invariant circle. The transition is characterized by the occurrence of phase slips, at a rate that is dependent on the amplitude and detuning of the applied drive. The resultant staircase structure in the phase of the oscillation can be described by the stochastic Adler equation, which reproduces the statistics of phase slip production.

The Presence of Vascular Mimicry Predicts High Risk of Clear Cell Renal Cell Carcinoma after Radical Nephrectomy.

PubMed

Zhou, Lin; Chang, Yuan; Xu, Le; Liu, Zheng; Fu, Qiang; Yang, Yuanfeng; Lin, Zongming; Xu, Jiejie

2016-08-01

Vascular mimicry is a type of tumor cell plasticity. The aim of this study was to determine the prognostic value of vascular mimicry in patients with clear cell renal cell carcinoma. We performed a retrospective cohort study in 387 patients with clear cell renal cell carcinoma who underwent radical nephrectomy at Zhongshan Hospital, Fudan University between 2008 and 2009. Pathological features, baseline patient characteristics and followup data were recorded. Vascular mimicry in clear cell renal cell carcinoma tissue was identified by CD31-periodic acid-Schiff double staining. Univariate and multivariate Cox regression models were used to analyze the impact of prognostic factors on recurrence-free survival. The concordance index and the Akaike information criterion were used to assess the predictive accuracy and sufficiency of different models. Positive vascular mimicry staining occurred in 25 of 387 clear cell renal cell carcinoma cases (6.5%) and it was associated with an increased risk of recurrence (log-rank p <0.001). Incorporating vascular mimicry into pT stage, Fuhrman grade and Leibovich score helped refine individual risk stratification. Moreover, vascular mimicry was identified as an independent prognostic factor (p = 0.001). It was entered into a nomogram together with pT stage, Fuhrman grade, tumor size and necrosis. In the primary cohort the Harrell concordance index for the established nomogram to predict recurrence-free survival was slightly higher than that of the Leibovich model (0.850 vs. 0.823), which failed to reach statistical significance (p = 0.158). Vascular mimicry could be a potential prognosticator for recurrence-free survival in patients with clear cell renal cell carcinoma after radical nephrectomy. Further external validation and functional analysis should be pursued to assess its potential prognostic and therapeutic values for clear cell renal cell carcinoma. Copyright © 2016 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Comparative characterization of stromal vascular cells derived from three types of vascular wall and adipose tissue.

PubMed

Yang, Santsun; Eto, Hitomi; Kato, Harunosuke; Doi, Kentaro; Kuno, Shinichiro; Kinoshita, Kahori; Ma, Hsu; Tsai, Chi-Han; Chou, Wan-Ting; Yoshimura, Kotaro

2013-12-01

Multipotent stem/progenitor cells localize perivascularly in many organs and vessel walls. These tissue-resident stem/progenitor cells differentiate into vascular endothelial cells, pericytes, and other mesenchymal lineages, and participate in physiological maintenance and repair of vasculatures. In this study, we characterized stromal vascular cells obtained through the explant culture method from three different vessel walls in humans: arterial wall (ART; >500 μm in diameter), venous wall (VN; >500 μm in diameter), and small vessels in adipose tissue (SV; arterioles and venules, <100 μm in diameter). These were examined for functionality and compared with adipose-derived stem/stromal cells (ASCs). All stromal vascular cells of different origins presented fibroblast-like morphology and we could not visually discriminate one population from another. Flow cytometry showed that the cultured population heterogeneously expressed a variety of surface antigens associated with stem/progenitor cells, but CD105 was expressed by most cells in all groups, suggesting that the cells generally shared the characteristics of mesenchymal stem cells. Our histological and flow cytometric data suggested that the main population of vessel wall-derived stromal vascular cells were CD34(+)/CD31(-) and came from the tunica adventitia and areola tissue surrounding the adventitia. CD271 (p75NTR) was expressed by the vasa vasorum in the VN adventitia and by a limited population in the adventitia of SV. All three populations differentiated into multiple lineages as did ASCs. ART cells induced the largest quantity of calcium formation in the osteogenic medium, whereas ASCs showed the greatest adipogenic differentiation. SV and VN stromal cells had greater potency for network formation than did ART stromal cells. In conclusion, the three stromal vascular populations exhibited differential functional properties. Our results have clinical implications for vascular diseases such as arterial wall calcification and possible applications to regenerative therapies involving each vessel wall-resident stromal population.

PINUS cembra L: histo-anatomical features, antioxidant enzyme activities and heavy metal contents of leaves and long shoots.

PubMed

Lungu, Cristina; Stănescu, Irina; Cojocaru, Sabina Ioana; Ciobanu, C; Ivănescu, Bianca; Miron, Anca

2015-01-01

This study aimed to investigate the histo-anatomical features of the long shoots and leaves (young and mature) of Pinus cembra L.. The activity of antioxidant enzymatic systems and the content of heavy metals were also evaluated. For the histo-anatomical study, the cross-sections were performed by usual techniques. The activity of antioxidant enzymatic systems (superoxide dismutase, catalase and peroxidase) was evaluated by spectrophotometric methods. The content of heavy metals was determined by atomic absorption spectroscopy. The cross-section through the long shoots shows many resiniferous canals and a periderm of variable thickness. The leaf has a triangular shape and only two vascular bundles in the inferior and upper levels. The highest level of superoxide dismutase activity (344.90 U/mg protein) was determined in the long shoots collected from a cembran pine in Vatra Dornei, while the highest level of peroxidase activity (7611.11 U/mg protein) was found in the leaves collected in Calimani Mountains. Cd level in all samples was under the quantification limit. Higher levels of Pb were determined in the long shoots (3 μg/g dry weight for the vegetal material collected in Vatra Dornei and 2.86 μg/g dry weight for the vegetal material collected in Calimani Mountains). Pinus cembra L. leaves show specific elements of subgenus Strobus (a triangular shape of the cross section, one single vascular bundle and two resiniferous canals). The results obtained for the superoxide dismutase and peroxidase activities corroborated with those obtained for the heavy metal contents indicate that antioxidant enzymes play an important role in the protection of Pinus cembra L. against exogenous stress factors.

Limitation of Unloading in the Developing Grains Is a Possible Cause Responsible for Low Stem Non-structural Carbohydrate Translocation and Poor Grain Yield Formation in Rice through Verification of Recombinant Inbred Lines

PubMed Central

Li, Guohui; Pan, Junfeng; Cui, Kehui; Yuan, Musong; Hu, Qiuqian; Wang, Wencheng; Mohapatra, Pravat K.; Nie, Lixiao; Huang, Jianliang; Peng, Shaobing

2017-01-01

Remobilisation of non-structural carbohydrates (NSC) from leaves and stems and unloading into developing grains are essential for yield formation of rice. In present study, three recombinant inbred lines of rice, R91, R156 and R201 have been tested for source-flow-sink related attributes determining the nature of NSC accumulation and translocation at two nitrogen levels in the field. Compared to R91 and R156, R201 had lower grain filling percentage, harvest index, and grain yield. Meanwhile, R201 had significantly lower stem NSC translocation during grain filling stage. Grain filling percentage, harvest index, and grain yield showed the consistent trend with stem NSC translocation among the three lines. In comparison with R91 and R156, R201 had similarity in leaf area index, specific leaf weight, stem NSC concentration at heading, biomass, panicles m-2, spikelets per panicle, remobilization capability of assimilation in stems, sink capacity, sink activity, number and cross sectional area of small vascular bundles, greater number and cross sectional area of large vascular bundles, and higher SPAD, suggesting that source, flow, and sink were not the limiting factors for low stem NSC translocation and grain filling percentage of R201. However, R201 had significant higher stem and rachis NSC concentrations at maturity, which implied that unloading in the developing grains might result in low NSC translocation in R201. The results indicate that stem NSC translocation could be beneficial for enhancement of grain yield potential, and poor unloading into caryopsis may be the possible cause of low stem NSC translocation, poor grain filling and yield formation in R201. PMID:28848573

Converging roads: evidence for an adult hemangioblast.

PubMed

Bailey, Alexis S; Fleming, William H

2003-11-01

Classical studies of the developing embryo first suggested the existence of the hemangioblast, a precursor cell with the potential to differentiate into both blood and blood vessels. Several lines of investigation demonstrated that many of the genes activated during early hematopoietic development are also expressed in the vascular endothelium. Gene-targeting studies using embryonic stem cells have identified Flk-1, SCL, and Runx-1 as important regulatory molecules that specify both hematopoietic and vascular outcomes. Although it was anticipated that the hemangioblast would be present only during the earliest stages of vascular development in the yolk sac, accumulating evidence now indicates that hematopoietic cells with hemangioblast activity persist into adulthood. In the adult, bone marrow-derived, circulating endothelial progenitors contribute to postnatal neovascularization and enhance vascular repair following ischemic injury. Highly purified populations of hematopoietic stem cells from humans and mice can differentiate into both blood cells and vascular tissue at the single cell level. These recent findings suggest that bone marrow-derived hematopoietic stem cells or their progeny may contribute to the maintenance and repair of both the hematopoietic and the vascular systems during adult life.

Assembly Kinetics Determine the Architecture of α-actinin Crosslinked F-actin Networks

PubMed Central

Falzone, Tobias T.; Lenz, Martin; Kovar, David R.; Gardel, Margaret L.

2013-01-01

The actin cytoskeleton is organized into diverse meshworks and bundles that support many aspects of cell physiology. Understanding the self-assembly of these actin-based structures is essential for developing predictive models of cytoskeletal organization. Here we show that the competing kinetics of bundle formation with the onset of dynamic arrest arising from filament entanglements and cross-linking determine the architecture of reconstituted actin networks formed with α-actinin cross-links. Cross-link mediated bundle formation only occurs in dilute solutions of highly mobile actin filaments. As actin polymerization proceeds, filament mobility and bundle formation are arrested concomitantly. By controlling the onset of dynamic arrest, perturbations to actin assembly kinetics dramatically alter the architecture of biochemically identical samples. Thus, the morphology of reconstituted F-actin networks is a kinetically determined structure similar to those formed by physical gels and glasses. These results establish mechanisms controlling the structure and mechanics in diverse semi-flexible biopolymer networks. PMID:22643888

Fibronectin Deposition Participates in Extracellular Matrix Assembly and Vascular Morphogenesis

PubMed Central

Hielscher, Abigail; Ellis, Kim; Qiu, Connie; Porterfield, Josh; Gerecht, Sharon

2016-01-01

The extracellular matrix (ECM) has been demonstrated to facilitate angiogenesis. In particular, fibronectin has been documented to activate endothelial cells, resulting in their transition from a quiescent state to an active state in which the cells exhibit enhanced migration and proliferation. The goal of this study is to examine the role of polymerized fibronectin during vascular tubulogenesis using a 3 dimensional (3D) cell-derived de-cellularized matrix. A fibronectin-rich 3D de-cellularized ECM was used as a scaffold to study vascular morphogenesis of endothelial cells (ECs). Confocal analyses of several matrix proteins reveal high intra- and extra-cellular deposition of fibronectin in formed vascular structures. Using a small peptide inhibitor of fibronectin polymerization, we demonstrate that inhibition of fibronectin fibrillogenesis in ECs cultured atop de-cellularized ECM resulted in decreased vascular morphogenesis. Further, immunofluorescence and ultrastructural analyses reveal decreased expression of stromal matrix proteins in the absence of polymerized fibronectin with high co-localization of matrix proteins found in association with polymerized fibronectin. Evaluating vascular kinetics, live cell imaging showed that migration, migration velocity, and mean square displacement, are disrupted in structures grown in the absence of polymerized fibronectin. Additionally, vascular organization failed to occur in the absence of a polymerized fibronectin matrix. Consistent with these observations, we tested vascular morphogenesis following the disruption of EC adhesion to polymerized fibronectin, demonstrating that block of integrins α5β1 and αvβ3, abrogated vascular morphogenesis. Overall, fibronectin deposition in a 3D cell-derived de-cellularized ECM appears to be imperative for matrix assembly and vascular morphogenesis. PMID:26811931

Vascular wall progenitor cells in health and disease.

PubMed

Psaltis, Peter J; Simari, Robert D

2015-04-10

The vasculature plays an indispensible role in organ development and maintenance of tissue homeostasis, such that disturbances to it impact greatly on developmental and postnatal health. Although cell turnover in healthy blood vessels is low, it increases considerably under pathological conditions. The principle sources for this phenomenon have long been considered to be the recruitment of cells from the peripheral circulation and the re-entry of mature cells in the vessel wall back into cell cycle. However, recent discoveries have also uncovered the presence of a range of multipotent and lineage-restricted progenitor cells in the mural layers of postnatal blood vessels, possessing high proliferative capacity and potential to generate endothelial, smooth muscle, hematopoietic or mesenchymal cell progeny. In particular, the tunica adventitia has emerged as a progenitor-rich compartment with niche-like characteristics that support and regulate vascular wall progenitor cells. Preliminary data indicate the involvement of some of these vascular wall progenitor cells in vascular disease states, adding weight to the notion that the adventitia is integral to vascular wall pathogenesis, and raising potential implications for clinical therapies. This review discusses the current body of evidence for the existence of vascular wall progenitor cell subpopulations from development to adulthood and addresses the gains made and significant challenges that lie ahead in trying to accurately delineate their identities, origins, regulatory pathways, and relevance to normal vascular structure and function, as well as disease. © 2015 American Heart Association, Inc.

Simultaneous submicrometric 3D imaging of the micro-vascular network and the neuronal system in a mouse spinal cord

PubMed Central

Fratini, Michela; Bukreeva, Inna; Campi, Gaetano; Brun, Francesco; Tromba, Giuliana; Modregger, Peter; Bucci, Domenico; Battaglia, Giuseppe; Spanò, Raffaele; Mastrogiacomo, Maddalena; Requardt, Herwig; Giove, Federico; Bravin, Alberto; Cedola, Alessia

2015-01-01

Faults in vascular (VN) and neuronal networks of spinal cord are responsible for serious neurodegenerative pathologies. Because of inadequate investigation tools, the lacking knowledge of the complete fine structure of VN and neuronal system represents a crucial problem. Conventional 2D imaging yields incomplete spatial coverage leading to possible data misinterpretation, whereas standard 3D computed tomography imaging achieves insufficient resolution and contrast. We show that X-ray high-resolution phase-contrast tomography allows the simultaneous visualization of three-dimensional VN and neuronal systems of ex-vivo mouse spinal cord at scales spanning from millimeters to hundreds of nanometers, with nor contrast agent nor sectioning and neither destructive sample-preparation. We image both the 3D distribution of micro-capillary network and the micrometric nerve fibers, axon-bundles and neuron soma. Our approach is very suitable for pre-clinical investigation of neurodegenerative pathologies and spinal-cord-injuries, in particular to resolve the entangled relationship between VN and neuronal system. PMID:25686728

Lateral Movement of Water and Sugar Across Xylem in Sugarcane Stalks

PubMed Central

Bull, T. A.; Gayler, K. R.; Glasziou, K. T.

1972-01-01

Laterally connected vascular bundles in the nodes of sugarcane (Saccharum species cv. Pindar) stalks allow a rapid redistribution of water across the stalk should the vascular continuity be partly disrupted. Tritiated water supplied to the roots exchanged rapidly between the xylem and storage tissue so that net movement up the stalk was slow. The half-time for exchange in a labeled stalk was about 4 hours so that the entire water content of a sugarcane stalk can turn over at least once in a single day. No rapid flux of sugar between xylem and phloem or xylem and storage tissue was detected. Functional xylem contained only low sugar concentrations: less than 0.3% w/v in the stalk and less than 0.02% w/v in the leaf. Previous reports of high sugar levels (9% w/v) in sugarcane stalk xylem reflect some degree of xylem blockage followed by a slow equilibration with free space sugars in the storage tissue. PMID:16658067

Cyclophilin A in cardiovascular homeostasis and diseases.

PubMed

Satoh, Kimio

2015-01-01

Vascular homeostasis is regulated by complex interactions between many vascular cell components, including endothelial cells, vascular smooth muscle cells (VSMCs), adventitial inflammatory cells, and autonomic nervous system. The balance between oxidant and antioxidant systems determines intracellular redox status, and their imbalance can cause oxidative stress. Excessive oxidative stress is one of the important stimuli that induce cellular damage and dysregulation of vascular cell components, leading to vascular diseases through multiple pathways. Cyclophilin A (CyPA) is one of the causative proteins that mediate oxidative stress-induced cardiovascular dysfunction. CyPA was initially discovered as the intracellular receptor of the immunosuppressive drug cyclosporine 30 years ago. However, recent studies have established that CyPA is secreted from vascular cell components, such as endothelial cells and VSMCs. Extracellular CyPA augments the development of cardiovascular diseases. CyPA secretion is regulated by Rho-kinase, which contributes to the pathogenesis of vasospasm, arteriosclerosis, ischemia/reperfusion injury, hypertension, pulmonary hypertension, and heart failure. We recently reported that plasma CyPA levels are significantly higher in patients with coronary artery disease, which is associated with increased numbers of stenotic coronary arteries and the need for coronary intervention in such patients. Furthermore, we showed that the vascular erythropoietin (Epo)/Epo receptor system plays an important role in production of nitric oxide and maintenance of vascular redox state and homeostasis, with a potential mechanistic link to the Rho-kinase-CyPA pathway. In this article, I review the data on the protective role of the vascular Epo/Epo receptor system and discuss the roles of the CyPA/Rho-kinase system in cardiovascular diseases.

Reciprocal interactions between endothelial cells and macrophages in angiogenic vascular niches

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baer, Caroline; Squadrito, Mario Leonardo; Iruela-Arispe, M. Luisa, E-mail: arispe@mcdb.ucla.edu

The ability of macrophages to promote vascular growth has been associated with the secretion and local delivery of classic proangiogenic factors (e.g., VEGF-A and proteases). More recently, a series of studies have also revealed that physical contact of macrophages with growing blood vessels coordinates vascular fusion of emerging sprouts. Interestingly, the interactions between macrophages and vascular endothelial cells (ECs) appear to be bidirectional, such that activated ECs also support the expansion and differentiation of proangiogenic macrophages from myeloid progenitors. Here, we discuss recent findings suggesting that dynamic angiogenic vascular niches might also exist in vivo, e.g. in tumors, where sproutingmore » blood vessels and immature myeloid cells like monocytes engage in heterotypic interactions that are required for angiogenesis. Finally, we provide an account of emerging mechanisms of cell-to-cell communication that rely on secreted microvesicles, such as exosomes, which can offer a vehicle for the rapid exchange of molecules and genetic information between macrophages and ECs engaged in angiogenesis. -- Highlights: • Macrophages promote angiogenesis by secreting proangiogenic factors. • Macrophages modulate angiogenesis via cell-to-cell contacts with endothelial cells. • Endothelial cells promote the differentiation of proangiogenic macrophages. • Macrophages and endothelial cells may cooperate to form angiogenic vascular niches.« less

Brain vascular pericytes following ischemia have multipotential stem cell activity to differentiate into neural and vascular lineage cells.

PubMed

Nakagomi, Takayuki; Kubo, Shuji; Nakano-Doi, Akiko; Sakuma, Rika; Lu, Shan; Narita, Aya; Kawahara, Maiko; Taguchi, Akihiko; Matsuyama, Tomohiro

2015-06-01

Brain vascular pericytes (PCs) are a key component of the blood-brain barrier (BBB)/neurovascular unit, along with neural and endothelial cells. Besides their crucial role in maintaining the BBB, increasing evidence shows that PCs have multipotential stem cell activity. However, their multipotency has not been considered in the pathological brain, such as after an ischemic stroke. Here, we examined whether brain vascular PCs following ischemia (iPCs) have multipotential stem cell activity and differentiate into neural and vascular lineage cells to reconstruct the BBB/neurovascular unit. Using PCs extracted from ischemic regions (iPCs) from mouse brains and human brain PCs cultured under oxygen/glucose deprivation, we show that PCs developed stemness presumably through reprogramming. The iPCs revealed a complex phenotype of angioblasts, in addition to their original mesenchymal properties, and multidifferentiated into cells from both a neural and vascular lineage. These data indicate that under ischemic/hypoxic conditions, PCs can acquire multipotential stem cell activity and can differentiate into major components of the BBB/neurovascular unit. Thus, these findings support the novel concept that iPCs can contribute to both neurogenesis and vasculogenesis at the site of brain injuries. © 2015 AlphaMed Press.

Intermicrotubular actin filaments in the transalar cytoskeletal arrays of Drosophila.

PubMed

Mogensen, M M; Tucker, J B

1988-11-01

Rabbit muscle myosin subfragment S1 decorates 6 nm diameter filaments in Drosophila wing epidermal cells in the arrowhead fashion characteristic of the binding of subfragment S1 to actin filaments. The filaments in question are concentrated between microtubules that are mostly composed of 15 protofilaments and form cell surface-associated transcellular bundles. There are indications that the majority of the actin filaments have the same polarity and that, like the microtubules, they may elongate from sites at the apical surfaces of the cells. The bundles of F actin and microtubules occur in dorsal and ventral epidermal cell layers of a wing blade. They are joined in dorso-ventral pairs by attachment desmosomes. These transalar cytoskeletal arrays may provide an example of a situation where actin filaments operate as stiffeners rather than active generators of force in conjunction with myosin. The arrays probably function as noncontractile pillars to maintain basal cell extensions and keep haemocoelic spaces open in the highly folded and expanding wing blades of late pupae.

A basis for customising perimetric locations within the macula in glaucoma.

PubMed

Alluwimi, Muhammed S; Swanson, William H; Malinovsky, Victor E; King, Brett J

2018-03-01

It has been recognised that the 24-2 grid used for perimetry may poorly sample the macula, which has been recently identified as a critical region for diagnosing and managing patients with glaucoma. We compared data derived from patients and controls to investigate the efficacy of a basis for customising perimetric locations within the macula, guided by en face images of retinal nerve fibre layer (RNFL) bundles. We used SD-OCT en face montages (www.heidelbergengineering.com) of the RNFL in 10 patients with glaucoma (ages 56-80 years, median 67.5 years) and 30 age-similar controls (ages 47-77, median 58). These patients were selected because of either the absence of perimetric defect while glaucomatous damage to the RNFL bundles was observed, or because of perimetric defect that did not reflect the extent and locations of the glaucomatous damage that appeared in the RNFL images. We used a customised blob stimulus for perimetric testing (a Gaussian blob with 0.25° standard deviation) at 10-2 grid locations, to assess the correspondence between perimetric defects and damaged RNFL bundles observed on en face images and perimetric defects. Data from the age-similar controls were used to compute total deviation (TD) and pattern deviation (PD) values at each location; a perimetric defect for a location was defined as a TD or PD value of -0.5 log unit or deeper. A McNemar's test was used to compare the proportions of locations with perimetric defects that fell outside the damaged RNFL bundles, with and without accounting for displacement of ganglion cell bodies. All patients but one had perimetric defects that were consistent with the patterns of damaged RNFL bundles observed on the en face images. We found six abnormal perimetric locations of 2040 tested in controls and 132 abnormal perimetric locations of 680 tested in patients. The proportions of abnormal locations that fell outside the damaged RNFL bundles, with and without accounting for displacement of the ganglion cell bodies were 0.08 and 0.07, respectively. The difference between the two proportions did not reach statistical significance (p = 0.5 for a one-tailed test). We demonstrated that it is effective to customise perimetric locations within the macula, guided by en face images of the RNFL bundles. The perimetric losses found with a 10-2 grid demonstrated similar patterns as the damaged RNFL bundles observed on the en face images. © 2018 The Authors. Ophthalmic and Physiological Optics published by John Wiley & Sons Ltd on behalf of College of Optometrists.

Early Lessons on Bundled Payment at an Academic Medical Center.

PubMed

Jubelt, Lindsay E; Goldfeld, Keith S; Blecker, Saul B; Chung, Wei-Yi; Bendo, John A; Bosco, Joseph A; Errico, Thomas J; Frempong-Boadu, Anthony K; Iorio, Richard; Slover, James D; Horwitz, Leora I

2017-09-01

Orthopaedic care is shifting to alternative payment models. We examined whether New York University Langone Medical Center achieved savings under the Centers for Medicare and Medicaid Services Bundled Payments for Care Improvement initiative. This study was a difference-in-differences study of Medicare fee-for-service patients hospitalized from April 2011 to June 2012 and October 2013 to December 2014 for lower extremity joint arthroplasty, cardiac valve procedures, or spine surgery (intervention groups), or for congestive heart failure, major bowel procedures, medical peripheral vascular disorders, medical noninfectious orthopaedic care, or stroke (control group). We examined total episode costs and costs by service category. We included 2,940 intervention episodes and 1,474 control episodes. Relative to the trend in the control group, lower extremity joint arthroplasty episodes achieved the greatest savings: adjusted average episode cost during the intervention period decreased by $3,017 (95% confidence interval [CI], -$6,066 to $31). For cardiac procedures, the adjusted average episode cost decreased by $2,999 (95% CI, -$8,103 to $2,105), and for spinal fusion, it increased by $8,291 (95% CI, $2,879 to $13,703). Savings were driven predominantly by shifting postdischarge care from inpatient rehabilitation facilities to home. Spinal fusion index admission costs increased because of changes in surgical technique. Under bundled payment, New York University Langone Medical Center decreased total episode costs in patients undergoing lower extremity joint arthroplasty. For patients undergoing cardiac valve procedures, evidence of savings was not as strong, and for patients undergoing spinal fusion, total episode costs increased. For all three conditions, the proportion of patients referred to inpatient rehabilitation facilities upon discharge decreased. These changes were not associated with an increase in index hospital length of stay or readmission rate. Opportunities for savings under bundled payment may be greater for lower extremity joint arthroplasty than for other conditions.

NMDA-Type Glutamate Receptor Activation Promotes Vascular Remodeling and Pulmonary Arterial Hypertension.

PubMed

Dumas, Sébastien J; Bru-Mercier, Gilles; Courboulin, Audrey; Quatredeniers, Marceau; Rücker-Martin, Catherine; Antigny, Fabrice; Nakhleh, Morad K; Ranchoux, Benoit; Gouadon, Elodie; Vinhas, Maria-Candida; Vocelle, Matthieu; Raymond, Nicolas; Dorfmüller, Peter; Fadel, Elie; Perros, Frédéric; Humbert, Marc; Cohen-Kaminsky, Sylvia

2018-05-29

Excessive proliferation and apoptosis resistance in pulmonary vascular cells underlie vascular remodeling in pulmonary arterial hypertension (PAH). Specific treatments for PAH exist, mostly targeting endothelial dysfunction, but high pulmonary arterial pressure still causes heart failure and death. Pulmonary vascular remodeling may be driven by metabolic reprogramming of vascular cells to increase glutaminolysis and glutamate production. The N -methyl-d-aspartate receptor (NMDAR), a major neuronal glutamate receptor, is also expressed on vascular cells, but its role in PAH is unknown. We assessed the status of the glutamate-NMDAR axis in the pulmonary arteries of patients with PAH and controls through mass spectrometry imaging, Western blotting, and immunohistochemistry. We measured the glutamate release from cultured pulmonary vascular cells using enzymatic assays and analyzed NMDAR regulation/phosphorylation through Western blot experiments. The effect of NMDAR blockade on human pulmonary arterial smooth muscle cell proliferation was determined using a BrdU incorporation assay. We assessed the role of NMDARs in vascular remodeling associated to pulmonary hypertension, in both smooth muscle-specific NMDAR knockout mice exposed to chronic hypoxia and the monocrotaline rat model of pulmonary hypertension using NMDAR blockers. We report glutamate accumulation, upregulation of the NMDAR, and NMDAR engagement reflected by increases in GluN1-subunit phosphorylation in the pulmonary arteries of human patients with PAH. K v channel inhibition and type A-selective endothelin receptor activation amplified calcium-dependent glutamate release from human pulmonary arterial smooth muscle cell, and type A-selective endothelin receptor and platelet-derived growth factor receptor activation led to NMDAR engagement, highlighting crosstalk between the glutamate-NMDAR axis and major PAH-associated pathways. The platelet-derived growth factor-BB-induced proliferation of human pulmonary arterial smooth muscle cells involved NMDAR activation and phosphorylated GluN1 subunit localization to cell-cell contacts, consistent with glutamatergic communication between proliferating human pulmonary arterial smooth muscle cells via NMDARs. Smooth-muscle NMDAR deficiency in mice attenuated the vascular remodeling triggered by chronic hypoxia, highlighting the role of vascular NMDARs in pulmonary hypertension. Pharmacological NMDAR blockade in the monocrotaline rat model of pulmonary hypertension had beneficial effects on cardiac and vascular remodeling, decreasing endothelial dysfunction, cell proliferation, and apoptosis resistance while disrupting the glutamate-NMDAR pathway in pulmonary arteries. These results reveal a dysregulation of the glutamate-NMDAR axis in the pulmonary arteries of patients with PAH and identify vascular NMDARs as targets for antiremodeling treatments in PAH. © 2018 American Heart Association, Inc.

Skin integrated with perfusable vascular channels on a chip.

PubMed

Mori, Nobuhito; Morimoto, Yuya; Takeuchi, Shoji

2017-02-01

This paper describes a method for fabricating perfusable vascular channels coated with endothelial cells within a cultured skin-equivalent by fixing it to a culture device connected to an external pump and tubes. A histological analysis showed that vascular channels were constructed in the skin-equivalent, which showed a conventional dermal/epidermal morphology, and the endothelial cells formed tight junctions on the vascular channel wall. The barrier function of the skin-equivalent was also confirmed. Cell distribution analysis indicated that the vascular channels supplied nutrition to the skin-equivalent. Moreover, the feasibility of a skin-equivalent containing vascular channels as a model for studying vascular absorption was demonstrated by measuring test molecule permeation from the epidermal layer into the vascular channels. The results suggested that this skin-equivalent can be used for skin-on-a-chip applications including drug development, cosmetics testing, and studying skin biology. Copyright © 2016 Elsevier Ltd. All rights reserved.

Plant nuclei can contain extensive grooves and invaginations

NASA Technical Reports Server (NTRS)

Collings, D. A.; Carter, C. N.; Rink, J. C.; Scott, A. C.; Wyatt, S. E.; Allen, N. S.; Brown, C. S. (Principal Investigator)

2000-01-01

Plant cells can exhibit highly complex nuclear organization. Through dye-labeling experiments in untransformed onion epidermal and tobacco culture cells and through the expression of green fluorescent protein targeted to either the nucleus or the lumen of the endoplasmic reticulum/nuclear envelope in these cells, we have visualized deep grooves and invaginations into the large nuclei of these cells. In onion, these structures, which are similar to invaginations seen in some animal cells, form tubular or planelike infoldings of the nuclear envelope. Both grooves and invaginations are stable structures, and both have cytoplasmic cores containing actin bundles that can support cytoplasmic streaming. In dividing tobacco cells, invaginations seem to form during cell division, possibly from strands of the endoplasmic reticulum trapped in the reforming nucleus. The substantial increase in nuclear surface area resulting from these grooves and invaginations, their apparent preference for association with nucleoli, and the presence in them of actin bundles that support vesicle motility suggest that the structures might function both in mRNA export from the nucleus and in protein import from the cytoplasm to the nucleus.

Regulation of spinogenesis in mature Purkinje cells via mGluR/PKC-mediated phosphorylation of CaMKIIβ

PubMed Central

Sugawara, Takeyuki; Hisatsune, Chihiro; Miyamoto, Hiroyuki; Ogawa, Naoko; Mikoshiba, Katsuhiko

2017-01-01

Dendritic spines of Purkinje cells form excitatory synapses with parallel fiber terminals, which are the primary sites for cerebellar synaptic plasticity. Nevertheless, how density and morphology of these spines are properly maintained in mature Purkinje cells is not well understood. Here we show an activity-dependent mechanism that represses excessive spine development in mature Purkinje cells. We found that CaMKIIβ promotes spine formation and elongation in Purkinje cells through its F-actin bundling activity. Importantly, activation of group I mGluR, but not AMPAR, triggers PKC-mediated phosphorylation of CaMKIIβ, which results in dissociation of the CaMKIIβ/F-actin complex. Defective function of the PKC-mediated CaMKIIβ phosphorylation promotes excess F-actin bundling and leads to abnormally numerous and elongated spines in mature IP3R1-deficient Purkinje cells. Thus, our data suggest that phosphorylation of CaMKIIβ through the mGluR/IP3R1/PKC signaling pathway represses excessive spine formation and elongation in mature Purkinje cells. PMID:28607044

Plant Nuclei Can Contain Extensive Grooves and InvaginationsW⃞W⃞

PubMed Central

Collings, David A.; Carter, Crystal N.; Rink, Jochen C.; Scott, Amie C.; Wyatt, Sarah E.; Allen, Nina Strömgren

2000-01-01

Plant cells can exhibit highly complex nuclear organization. Through dye-labeling experiments in untransformed onion epidermal and tobacco culture cells and through the expression of green fluorescent protein targeted to either the nucleus or the lumen of the endoplasmic reticulum/nuclear envelope in these cells, we have visualized deep grooves and invaginations into the large nuclei of these cells. In onion, these structures, which are similar to invaginations seen in some animal cells, form tubular or planelike infoldings of the nuclear envelope. Both grooves and invaginations are stable structures, and both have cytoplasmic cores containing actin bundles that can support cytoplasmic streaming. In dividing tobacco cells, invaginations seem to form during cell division, possibly from strands of the endoplasmic reticulum trapped in the reforming nucleus. The substantial increase in nuclear surface area resulting from these grooves and invaginations, their apparent preference for association with nucleoli, and the presence in them of actin bundles that support vesicle motility suggest that the structures might function both in mRNA export from the nucleus and in protein import from the cytoplasm to the nucleus. PMID:11148288

Single microfilaments mediate the early steps of microtubule bundling during preprophase band formation in onion cotyledon epidermal cells

PubMed Central

Takeuchi, Miyuki; Karahara, Ichirou; Kajimura, Naoko; Takaoka, Akio; Murata, Kazuyoshi; Misaki, Kazuyo; Yonemura, Shigenobu; Staehelin, L. Andrew; Mineyuki, Yoshinobu

2016-01-01

The preprophase band (PPB) is a cytokinetic apparatus that determines the site of cell division in plants. It originates as a broad band of microtubules (MTs) in G2 and narrows to demarcate the future division site during late prophase. Studies with fluorescent probes have shown that PPBs contain F-actin during early stages of their development but become actin depleted in late prophase. Although this suggests that actins contribute to the early stages of PPB formation, how actins contribute to PPB-MT organization remains unsolved. To address this question, we used electron tomography to investigate the spatial relationship between microfilaments (MFs) and MTs at different stages of PPB assembly in onion cotyledon epidermal cells. We demonstrate that the PPB actins observed by fluorescence microscopy correspond to short, single MFs. A majority of the MFs are bound to MTs, with a subset forming MT-MF-MT bridging structures. During the later stages of PPB assembly, the MF-mediated links between MTs are displaced by MT-MT linkers as the PPB MT arrays mature into tightly packed MT bundles. On the basis of these observations, we propose that the primary function of actins during PPB formation is to mediate the initial bundling of the PPB MTs. PMID:27053663

Cytoskeletal mechanics: Structure and Dynamics

NASA Astrophysics Data System (ADS)

Bausch, Andreas

2008-03-01

The actin cytoskeleton, a dynamic network of semiflexible filaments and associated regulatory proteins, is responsible for the extraordinary viscoelastic properties of cells. Especially for cellular motility the controlled self assembly to defined structures and the dynamic reorganization on different time scales are of outstanding importance. A prominent example for the controlled self assembly are actin bundles: in many cytoskeletal processes cells rely on the tight control of the structural and mechanical properties of the actin bundles. Using an in vitro model system we show that size control relies on a mismatch between the helical structure of individual actin filaments and the packing symmetry within bundles. While such self assembled structure may evoke the picture of a static network the contrary is the case: the cytoskeleton is highly dynamic and a constant remodeling takes place in vivo. Such dynamic reorganization of the cytoskeleton relies on the non-static nature of single actin/ABP bonds. Here, we study the thermal and forced unbinding events of individual ABP in such in vitro networks. The binding kinetics of the transient crosslinkers determines the mechanical response of such networks -- in the linear as well in the non-linear regime. These effects are important prerequisites for the high adaptability of cells and at the same time might be the molecular mechanism employed by them for mechanosensing.

Specialized mouse embryonic stem cells for studying vascular development.

PubMed

Glaser, Drew E; Burns, Andrew B; Hatano, Rachel; Medrzycki, Magdalena; Fan, Yuhong; McCloskey, Kara E

2014-01-01

Vascular progenitor cells are desirable in a variety of therapeutic strategies; however, the lineage commitment of endothelial and smooth muscle cell from a common progenitor is not well-understood. Here, we report the generation of the first dual reporter mouse embryonic stem cell (mESC) lines designed to facilitate the study of vascular endothelial and smooth muscle development in vitro. These mESC lines express green fluorescent protein (GFP) under the endothelial promoter, Tie-2, and Discomsoma sp. red fluorescent protein (RFP) under the promoter for alpha-smooth muscle actin (α-SMA). The lines were then characterized for morphology, marker expression, and pluripotency. The mESC colonies were found to exhibit dome-shaped morphology, alkaline phosphotase activity, as well as expression of Oct 3/4 and stage-specific embryonic antigen-1. The mESC colonies were also found to display normal karyotypes and are able to generate cells from all three germ layers, verifying pluripotency. Tissue staining confirmed the coexpression of VE (vascular endothelial)-cadherin with the Tie-2 GFP+ expression on endothelial structures and smooth muscle myosin heavy chain with the α-SMA RFP+ smooth muscle cells. Lastly, it was verified that the developing mESC do express Tie-2 GFP+ and α-SMA RFP+ cells during differentiation and that the GFP+ cells colocalize with the vascular-like structures surrounded by α-SMA-RFP cells. These dual reporter vascular-specific mESC permit visualization and cell tracking of individual endothelial and smooth muscle cells over time and in multiple dimensions, a powerful new tool for studying vascular development in real time.

Arterial grafts exhibiting unprecedented cellular infiltration and remodeling in vivo: the role of cells in the vascular wall.

PubMed

Row, Sindhu; Peng, Haofan; Schlaich, Evan M; Koenigsknecht, Carmon; Andreadis, Stelios T; Swartz, Daniel D

2015-05-01

To engineer and implant vascular grafts in the arterial circulation of a pre-clinical animal model and assess the role of donor medial cells in graft remodeling and function. Vascular grafts were engineered using Small Intestinal Submucosa (SIS)-fibrin hybrid scaffold and implanted interpositionally into the arterial circulation of an ovine model. We sought to demonstrate implantability of SIS-Fibrin based grafts; examine the remodeling; and determine whether the presence of vascular cells in the medial wall was necessary for cellular infiltration from the host and successful remodeling of the implants. We observed no occlusions or anastomotic complications in 18 animals that received these grafts. Notably, the grafts exhibited unprecedented levels of host cell infiltration that was not limited to the anastomotic sites but occurred through the lumen as well as the extramural side, leading to uniform cell distribution. Incoming cells remodeled the extracellular matrix and matured into functional smooth muscle cells as evidenced by expression of myogenic markers and development of vascular reactivity. Interestingly, tracking the donor cells revealed that their presence was beneficial but not necessary for successful grafting. Indeed, the proliferation rate and number of donor cells decreased over time as the vascular wall was dominated by host cells leading to significant remodeling and development of contractile function. These results demonstrate that SIS-Fibrin grafts can be successfully implanted into the arterial circulation of a clinically relevant animal model, improve our understanding of vascular graft remodeling and raise the possibility of engineering mural cell-free arterial grafts. Copyright © 2015 Elsevier Ltd. All rights reserved.

Development of an optical time-resolved measurement system under high-pressure and low-temperature with a piston-cylinder pressure cell

NASA Astrophysics Data System (ADS)

Tsuchiya, Satoshi; Kino, Yohei; Nakagawa, Koichi; Nakagawa, Daisuke; Yamada, Jun-ichi; Toda, Yasunori

2016-04-01

To perform the femtosecond pump-probe spectroscopy under high pressure and low temperature, we constructed a measurement system with a piston cylinder type pressure cell installing an optical fiber bundle. The applied pressure was achieved to 6 kbar and the cell was cooled down to 15 K. Several demonstrations revealed that broadening and change of polarization of pulse (duration of ˜120 fs) owing to the dispersions in the fiber bundle are much small indicating that those have little influence on the measurement of carrier relaxation dynamics. In the measurements of κ-(BEDT-TTF)2Cu(NCS)2 under 1.3 kbar at 43 K, we have successfully detected the polarization anisotropy of the carrier relaxation dynamics and estimated the decay time in the same way as the normal measurement.

Development of an optical time-resolved measurement system under high-pressure and low-temperature with a piston-cylinder pressure cell.

PubMed

Tsuchiya, Satoshi; Kino, Yohei; Nakagawa, Koichi; Nakagawa, Daisuke; Yamada, Jun-Ichi; Toda, Yasunori

2016-04-01

To perform the femtosecond pump-probe spectroscopy under high pressure and low temperature, we constructed a measurement system with a piston cylinder type pressure cell installing an optical fiber bundle. The applied pressure was achieved to 6 kbar and the cell was cooled down to 15 K. Several demonstrations revealed that broadening and change of polarization of pulse (duration of ∼120 fs) owing to the dispersions in the fiber bundle are much small indicating that those have little influence on the measurement of carrier relaxation dynamics. In the measurements of κ-(BEDT-TTF)2Cu(NCS)2 under 1.3 kbar at 43 K, we have successfully detected the polarization anisotropy of the carrier relaxation dynamics and estimated the decay time in the same way as the normal measurement.

Cell-microenvironment interactions and architectures in microvascular systems

PubMed Central

Bersini, Simone; Yazdi, Iman K.; Talò, Giuseppe; Shin, Su Ryon; Moretti, Matteo; Khademhosseini, Ali

2016-01-01

In the past decade, significant advances have been made in the design and optimization of novel biomaterials and microfabrication techniques to generate vascularized tissues. Novel microfluidic systems have facilitated the development and optimization of in vitro models for exploring the complex pathophysiological phenomena that occur inside a microvascular environment. To date, most of these models have focused on engineering of increasingly complex systems, rather than analyzing the molecular and cellular mechanisms that drive microvascular network morphogenesis and remodeling. In fact, mutual interactions among endothelial cells (ECs), supporting mural cells and organ-specific cells, as well as between ECs and the extracellular matrix, are key driving forces for vascularization. This review focuses on the integration of materials science, microengineering and vascular biology for the development of in vitro microvascular systems. Various approaches currently being applied to study cell-cell/cell-matrix interactions, as well as biochemical/biophysical cues promoting vascularization and their impact on microvascular network formation, will be identified and discussed. Finally, this review will explore in vitro applications of microvascular systems, in vivo integration of transplanted vascularized tissues, and the important challenges for vascularization and controlling the microcirculatory system within the engineered tissues, especially for microfabrication approaches. It is likely that existing models and more complex models will further our understanding of the key elements of vascular network growth, stabilization and remodeling to translate basic research principles into functional, vascularized tissue constructs for regenerative medicine applications, drug screening and disease models. PMID:27417066

Cell-microenvironment interactions and architectures in microvascular systems.

PubMed

Bersini, Simone; Yazdi, Iman K; Talò, Giuseppe; Shin, Su Ryon; Moretti, Matteo; Khademhosseini, Ali

2016-11-01

In the past decade, significant advances have been made in the design and optimization of novel biomaterials and microfabrication techniques to generate vascularized tissues. Novel microfluidic systems have facilitated the development and optimization of in vitro models for exploring the complex pathophysiological phenomena that occur inside a microvascular environment. To date, most of these models have focused on engineering of increasingly complex systems, rather than analyzing the molecular and cellular mechanisms that drive microvascular network morphogenesis and remodeling. In fact, mutual interactions among endothelial cells (ECs), supporting mural cells and organ-specific cells, as well as between ECs and the extracellular matrix, are key driving forces for vascularization. This review focuses on the integration of materials science, microengineering and vascular biology for the development of in vitro microvascular systems. Various approaches currently being applied to study cell-cell/cell-matrix interactions, as well as biochemical/biophysical cues promoting vascularization and their impact on microvascular network formation, will be identified and discussed. Finally, this review will explore in vitro applications of microvascular systems, in vivo integration of transplanted vascularized tissues, and the important challenges for vascularization and controlling the microcirculatory system within the engineered tissues, especially for microfabrication approaches. It is likely that existing models and more complex models will further our understanding of the key elements of vascular network growth, stabilization and remodeling to translate basic research principles into functional, vascularized tissue constructs for regenerative medicine applications, drug screening and disease models. Copyright © 2016 Elsevier Inc. All rights reserved.

Nanotechnology in vascular tissue engineering: from nanoscaffolding towards rapid vessel biofabrication.

PubMed

Mironov, Vladimir; Kasyanov, Vladimir; Markwald, Roger R

2008-06-01

The existing methods of biofabrication for vascular tissue engineering are still bioreactor-based, extremely expensive, laborious and time consuming and, furthermore, not automated, which would be essential for an economically successful large-scale commercialization. The advances in nanotechnology can bring additional functionality to vascular scaffolds, optimize internal vascular graft surface and even help to direct the differentiation of stem cells into the vascular cell phenotype. The development of rapid nanotechnology-based methods of vascular tissue biofabrication represents one of most important recent technological breakthroughs in vascular tissue engineering because it dramatically accelerates vascular tissue assembly and, importantly, also eliminates the need for a bioreactor-based scaffold cellularization process.

Interleukin-17A and vascular remodelling in severe asthma; lack of evidence for a direct role.

PubMed

Panariti, A; Baglole, C J; Sanchez, V; Eidelman, D H; Hussain, S; Olivenstein, R; Martin, J G; Hamid, Q

2018-04-01

Bronchial vascular remodelling may contribute to the severity of airway narrowing through mucosal congestion. Interleukin (IL)-17A is associated with the most severe asthmatic phenotype but whether it might contribute to vascular remodelling is uncertain. To assess vascular remodelling in severe asthma and whether IL-17A directly or indirectly may cause endothelial cell activation and angiogenesis. Bronchial vascularization was quantified in asthmatic subjects, COPD and healthy subjects together with the number of IL-17A + cells as well as the concentration of angiogenic factors in the sputum. The effect of IL-17A on in vitro angiogenesis, cell migration and endothelial permeability was assessed directly on primary human lung microvascular endothelial cells (HMVEC-L) or indirectly with conditioned medium derived from normal bronchial epithelial cells (NHBEC), fibroblasts (NHBF) and airway smooth muscle cells (ASMC) after IL-17A stimulation. Severe asthmatics have increased vascularity compared to the other groups, which correlates positively with the concentrations of angiogenic factors in sputum. Interestingly, we demonstrated that increased bronchial vascularity correlates positively with the number of subepithelial IL-17A + cells. However IL-17A had no direct effect on HMVEC-L function but it enhanced endothelial tube formation and cell migration through the production of angiogenic factors by NHBE and ASMC. Our results shed light on the role of IL-17A in vascular remodelling, most likely through stimulating the synthesis of other angiogenic factors. Knowledge of these pathways may aid in the identification of new therapeutic targets. © 2018 John Wiley & Sons Ltd.

Angiopoietin–Tie signalling in the cardiovascular and lymphatic systems

PubMed Central

Eklund, Lauri; Kangas, Jaakko; Saharinen, Pipsa

2016-01-01

Endothelial cells that form the inner layer of blood and lymphatic vessels are important regulators of vascular functions and centrally involved in the pathogenesis of vascular diseases. In addition to the vascular endothelial growth factor (VEGF) receptor pathway, the angiopoietin (Ang)–Tie system is a second endothelial cell specific ligand–receptor signalling system necessary for embryonic cardiovascular and lymphatic development. The Ang–Tie system also regulates postnatal angiogenesis, vessel remodelling, vascular permeability and inflammation to maintain vascular homoeostasis in adult physiology. This system is implicated in numerous diseases where the vasculature has an important contribution, such as cancer, sepsis, diabetes, atherosclerosis and ocular diseases. Furthermore, mutations in the TIE2 signalling pathway cause defects in vascular morphogenesis, resulting in venous malformations and primary congenital glaucoma. Here, we review recent advances in the understanding of the Ang–Tie signalling system, including cross-talk with the vascular endothelial protein tyrosine phosphatase (VE-PTP) and the integrin cell adhesion receptors, focusing on the Ang–Tie system in vascular development and pathogenesis of vascular diseases. PMID:27941161

Forskolin Modifies Retinal Vascular Development in Mrp4-Knockout Mice

PubMed Central

Matsumiya, Wataru; Kusuhara, Sentaro; Hayashibe, Keiko; Maruyama, Kazuichi; Kusuhara, Hiroyuki; Tagami, Mizuki; Schuetz, John D.; Negi, Akira

2012-01-01

Purpose. Multidrug resistance protein 4 (MRP4) effluxes a wide variety of endogenous compounds, including cyclic adenosine monophosphate (cAMP), and is exclusively expressed in vascular endothelial cells (ECs) of the retina. This study aimed to investigate the role of MRP4 in retinal vascular development. Methods. The retinal vascular phenotype of Mrp4−/− mice was examined by whole-mount immunohistochemistry at P3, P6, and P14. The retinas from P6 pups that received an intraperitoneal injection of either solvent control or forskolin, an inducer of intracellular cAMP formation, at P4 and P5 were analyzed in terms of their vascular formation (vascular length, vascular branching, vascular density, and the number of tip cells), cell proliferation and apoptosis, and vessel stability. Results. The Mrp4−/− mice exhibited no overt abnormalities in the development of the retinal vasculature, but retinal vascular development in the Mrp4−/− mice was suppressed in response to forskolin administration. There was a significant decrease in the vascular length, vascular branching, and vascular density, and inhibited tip cell formation at the vascular front. The forskolin-treated Mrp4−/− mice showed an increased number of Ki67-positive and cleaved caspase 3–positive ECs, a significant decrease in the amount of pericyte coverage, and a reduced number of empty sleeves. In pups exposed to hyperoxia (75% oxygen) from P7 to P12, the Mrp4−/− mice showed a significant increase in the unvascularized retinal area. Conclusions. Mrp4−/− mice exhibited suppressed retinal vascular development in response to forskolin treatment. Thus, Mrp4 might have protective roles in retinal vascular development by regulating the intracellular cAMP level. PMID:23154460

Forskolin modifies retinal vascular development in Mrp4-knockout mice.

PubMed

Matsumiya, Wataru; Kusuhara, Sentaro; Hayashibe, Keiko; Maruyama, Kazuichi; Kusuhara, Hiroyuki; Tagami, Mizuki; Schuetz, John D; Negi, Akira

2012-12-07

Multidrug resistance protein 4 (MRP4) effluxes a wide variety of endogenous compounds, including cyclic adenosine monophosphate (cAMP), and is exclusively expressed in vascular endothelial cells (ECs) of the retina. This study aimed to investigate the role of MRP4 in retinal vascular development. The retinal vascular phenotype of Mrp4(-/-) mice was examined by whole-mount immunohistochemistry at P3, P6, and P14. The retinas from P6 pups that received an intraperitoneal injection of either solvent control or forskolin, an inducer of intracellular cAMP formation, at P4 and P5 were analyzed in terms of their vascular formation (vascular length, vascular branching, vascular density, and the number of tip cells), cell proliferation and apoptosis, and vessel stability. The Mrp4(-/-) mice exhibited no overt abnormalities in the development of the retinal vasculature, but retinal vascular development in the Mrp4(-/-) mice was suppressed in response to forskolin administration. There was a significant decrease in the vascular length, vascular branching, and vascular density, and inhibited tip cell formation at the vascular front. The forskolin-treated Mrp4(-/-) mice showed an increased number of Ki67-positive and cleaved caspase 3-positive ECs, a significant decrease in the amount of pericyte coverage, and a reduced number of empty sleeves. In pups exposed to hyperoxia (75% oxygen) from P7 to P12, the Mrp4(-/-) mice showed a significant increase in the unvascularized retinal area. Mrp4(-/-) mice exhibited suppressed retinal vascular development in response to forskolin treatment. Thus, Mrp4 might have protective roles in retinal vascular development by regulating the intracellular cAMP level.

Lipid-Polymer Nanoparticles Encapsulating Curcumin for Modulating the Vascular Deposition of Breast Cancer Cells

PubMed Central

Palange, Anna L.; Di Mascolo, Daniele; Carallo, Claudio; Gnasso, Agostino; Decuzzi, Paolo

2014-01-01

Vascular adhesion and endothelial transmigration are critical steps in the establishment of distant metastasis by circulating tumor cells (CTCs). Also, vascular inflammation plays a pivotal role in steering CTCs out of the blood stream. Here, long circulating lipid-polymer nanoparticles encapsulating curcumin (NANOCurc) are proposed for modulating the vascular deposition of CTCs. Upon treatment with NANOCurc, the adhesion propensity of highly metastatic breast cancer cells (MDA-MB-231) onto TNF-α stimulated endothelial cells (HUVECs) reduces by ~ 70%, in a capillary flow. Remarkably, the CTC vascular deposition already reduces up to ~ 50% by treating solely the inflamed HUVECs. The CTC arrest is mediated by the interaction between ICAM-1 on HUVECs and MUC-1 on cancer cells, and moderate doses of curcumin down-regulate the expression of both molecules. This suggests that NANOCurc could prevent metastasis and limit the progression of the disease by modulating vascular inflammation and impairing the CTC arrest. PMID:24566270

Numerical Study of the Complex Temporal Pattern of Spontaneous Oscillation in Bullfrog Saccular Hair Cells

NASA Astrophysics Data System (ADS)

Roongthumskul, Yuttana; Fredrickson-Hemsing, Lea; Kao, Albert; Bozovic, Dolores

2011-11-01

Hair bundles of the bullfrog sacculus display spontaneous oscillations that show complex temporal profiles. Quiescent intervals are typically interspersed with oscillations, analogous to bursting behavior observed in neural systems. By introducing slow calcium dynamics into the theoretical model of bundle mechanics, we reproduce numerically the multi-mode oscillations and explore the effects of internal parameters on the temporal profiles and the frequency tuning of their linear response functions. We also study the effects of mechanical overstimulation on the oscillatory behavior.

Vestibular receptor cells and signal detection: bioaccelerometers and the hexagonal sampling of two-dimensional signals

NASA Technical Reports Server (NTRS)

Mugler, D. H.; Ross, M. D.

1990-01-01

The inner ear contains sensory organs which signal changes in head movement. The vestibular sacs, in particular, are sensitive to linear accelerations. Electron microscopic images have revealed the structure of tiny sensory hair bundles, whose mechanical deformation results in the initiation of neuronal activity and the transmission of electrical signals to the brain. The structure of the hair bundles is shown in this paper to be that of the most efficient two-dimensional phased-array signal processors.

Aldosterone mediates its rapid effects in vascular endothelial cells through GPER activation.

PubMed

Gros, Robert; Ding, Qingming; Liu, Bonan; Chorazyczewski, Jozef; Feldman, Ross D

2013-03-01

The importance of the rapid vascular effects of aldosterone is increasingly appreciated. Through these rapid pathways, aldosterone has been shown to regulate vascular contractility, cell growth, and apoptosis. In our most recent studies, we demonstrated the effects of aldosterone on cell growth and contractility in vascular smooth muscle cells. We showed that these effects could occur via activation of the classic mineralocorticoid receptor, as well the recently characterized G protein-coupled estrogen receptor (GPER), initially characterized as an estrogen-specific receptor. However, the mechanisms underlying aldosterone's endothelium-dependent actions are unknown. Furthermore, the ERK regulatory and proapoptotic effects of aldosterone mediated by GPER activation in cultured vascular smooth muscle cells were only apparent when GPER was reintroduced into these cells by gene transfer. Whether GPER activation via aldosterone might be an important regulator in native vascular cells has been questioned. Therefore, to determine the role of GPER in mediating aldosterone's effects on cell growth and vascular reactivity in native cells, we examined rat aortic vascular endothelial cells, a model characterized by persistent robust expression of GPER, but without detectable mineralocorticoid receptor expression. In these endothelial cells, the GPER agonist G1 mediates a rapid increase in ERK phosphorylation that is wholly GPER-dependent, paralleling the actions of aldosterone. The effects of G1 and aldosterone to stimulate ERK phosphorylation paralleled their proapoptotic and antiproliferative effects. In previous studies, we reported that aldosterone mediates a rapid endothelium-dependent vasodilatory effect, antagonistic to its direct vasoconstrictor effect in endothelium-denuded preparations. Using a rat aortic ring/organ bath preparation to determine the GPER dependence of aldosterone's endothelium-dependent vasodilator effects, we demonstrate that aldosterone inhibits phenylephrine-mediated contraction. This vasodilator effect parallels the actions of the GPER agonist G1. Furthermore, the effects of aldosterone were completely ablated by the GPER antagonist G15. These data support an important role of GPER activation in aldosterone-mediated regulation of endothelial cell growth, as well as in aldosterone's endothelium-mediated regulation of vasoreactivity.

Analysis for apoptosis and necrosis on adipocytes, stromal vascular fraction, and adipose-derived stem cells in human lipoaspirates after liposuction.

PubMed

Wang, Wei Z; Fang, Xin-Hua; Williams, Shelley J; Stephenson, Linda L; Baynosa, Richard C; Wong, Nancy; Khiabani, Kayvan T; Zamboni, William A

2013-01-01

Adipose-derived stem cells have become the most studied adult stem cells. The authors examined the apoptosis and necrosis rates for adipocyte, stromal vascular fraction, and adipose-derived stem cells in fresh human lipoaspirates. Human lipoaspirate (n = 8) was harvested using a standard liposuction technique. Stromal vascular fraction cells were separated from adipocytes and cultured to obtain purified adipose-derived stem cells. A panel of stem cell markers was used to identify the surface phenotypes of cultured adipose-derived stem cells. Three distinct stem cell subpopulations (CD90/CD45, CD105/CD45, and CD34/CD31) were selected from the stromal vascular fraction. Apoptosis and necrosis were determined by annexin V/propidium iodide assay and analyzed by flow cytometry. The cultured adipose-derived stem cells demonstrated long-term proliferation and differentiation evidenced by cell doubling time and positive staining with oil red O and alkaline phosphatase. Isolated from lipoaspirates, adipocytes exhibited 19.7 ± 3.7 percent apoptosis and 1.1 ± 0.3 percent necrosis; stromal vascular fraction cells revealed 22.0 ± 6.3 percent of apoptosis and 11.2 ± 1.9 percent of necrosis; stromal vascular fraction cells had a higher rate of necrosis than adipocytes (p < 0.05). Among the stromal vascular fraction cells, 51.1 ± 3.7 percent expressed CD90/CD45, 7.5 ± 1.0 percent expressed CD105/CD45, and 26.4 ± 3.8 percent expressed CD34/CD31. CD34/CD31 adipose-derived stem cells had lower rates of apoptosis and necrosis compared with CD105/CD45 adipose-derived stem cells (p < 0.05). Adipose-derived stem cells had a higher rate of apoptosis and necrosis than adipocytes. However, the extent of apoptosis and necrosis was significantly different among adipose-derived stem cell subpopulations.

The conflict between cell proliferation and expansion primarily affects stem organogenesis in Arabidopsis.

PubMed

Maeda, Saori; Gunji, Shizuka; Hanai, Kenya; Hirano, Tomonari; Kazama, Yusuke; Ohbayashi, Iwai; Abe, Tomoko; Sawa, Shinichiro; Tsukaya, Hirokazu; Ferjani, Ali

2014-11-01

Plant shoot organs such as stems, leaves and flowers are derived from specialized groups of stem cells organized at the shoot apical meristem (SAM). Organogenesis involves two major processes, namely cell proliferation and differentiation, whereby the former contributes to increasing the cell number and the latter involves substantial increases in cell volume through cell expansion. Co-ordination between the above processes in time and space is essential for proper organogenesis. To identify regulatory factors involved in proper organogenesis, heavy-ion beam-irradiated de-etiolated (det) 3-1 seeds have been used to identify striking phenotypes in the A#26-2; det3-1 mutant. In addition to the stunted plant stature mimicking det3-1, the A#26-2; det3-1 mutant exhibited stem thickening, increased floral organ number and a fruit shape reminiscent of clavata (clv) mutants. DNA sequencing analysis demonstrated that A#26-2; det3-1 harbors a mutation in the CLV3 gene. Importantly, A#26-2; det3-1 displayed cracks that randomly occurred on the main stem with a frequency of approximately 50%. Furthermore, the double mutants clv3-8 det3-1, clv1-4 det3-1 and clv2-1 det3-1 consistently showed stem cracks with frequencies of approximately 97, 38 and 35%, respectively. Cross-sections of stems further revealed an increase in vascular bundle number, cell number and size in the pith of clv3-8 det3-1 compared with det3-1. These findings suggest that the stem inner volume increase due to clv mutations exerts an outward mechanical stress; that in a det3-1 background (defective in cell expansion) resulted in cracking of the outermost layer of epidermal cells. © The Author 2014. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Brittle stalk 2 encodes a putative glycosylphosphatidylinositol-anchored protein that affects mechanical strength of maize tissues by altering the composition and structure of secondary cell walls.

PubMed

Ching, Ada; Dhugga, Kanwarpal S; Appenzeller, Laura; Meeley, Robert; Bourett, Timothy M; Howard, Richard J; Rafalski, Antoni

2006-10-01

A spontaneous maize mutant, brittle stalk-2 (bk2-ref), exhibits dramatically reduced tissue mechanical strength. Reduction in mechanical strength in the stalk tissue was highly correlated with a reduction in the amount of cellulose and an uneven deposition of secondary cell wall material in the subepidermal and perivascular sclerenchyma fibers. Cell wall accounted for two-thirds of the observed reduction in dry matter content per unit length of the mutant stalk in comparison to the wildtype stalk. Although the cell wall composition was significantly altered in the mutant in comparison to the wildtype stalks, no compensation by lignin and cell wall matrix for reduced cellulose amount was observed. We demonstrate that Bk2 encodes a Cobra-like protein that is homologous to the rice Bc1 protein. In the bk2-ref gene, a 1 kb transposon-like element is inserted in the beginning of the second exon, disrupting the open reading frame. The Bk2 gene was expressed in the stalk, husk, root, and leaf tissues, but not in the embryo, endosperm, pollen, silk, or other tissues with comparatively few or no secondary cell wall containing cells. The highest expression was in the isolated vascular bundles. In agreement with its role in secondary wall formation, the expression pattern of the Bk2 gene was very similar to that of the ZmCesA10, ZmCesA11, and ZmCesA12 genes, which are known to be involved in secondary wall formation. We have isolated an independent Mutator-tagged allele of bk2, referred to as bk2-Mu7, the phenotype of which is similar to that of the spontaneous mutant. Our results demonstrate that mutations in the Bk2 gene affect stalk strength in maize by interfering with the deposition of cellulose in the secondary cell wall in fiber cells.

Concurrent generation of functional smooth muscle and endothelial cells via a vascular progenitor.

PubMed

Marchand, Melanie; Anderson, Erica K; Phadnis, Smruti M; Longaker, Michael T; Cooke, John P; Chen, Bertha; Reijo Pera, Renee A

2014-01-01

Smooth muscle cells (SMCs) and endothelial cells (ECs) are typically derived separately, with low efficiencies, from human pluripotent stem cells (hPSCs). The concurrent generation of these cell types might lead to potential applications in regenerative medicine to model, elucidate, and eventually treat vascular diseases. Here we report a robust two-step protocol that can be used to simultaneously generate large numbers of functional SMCs and ECs from a common proliferative vascular progenitor population via a two-dimensional culture system. We show here that coculturing hPSCs with OP9 cells in media supplemented with vascular endothelial growth factor, basic fibroblast growth factor, and bone morphogenetic protein 4 yields a higher percentage of CD31(+)CD34(+) cells on day 8 of differentiation. Upon exposure to endothelial differentiation media and SM differentiation media, these vascular progenitors were able to differentiate and mature into functional endothelial cells and smooth muscle cells, respectively. Furthermore, we were able to expand the intermediate population more than a billion fold to generate sufficient numbers of ECs and SMCs in parallel for potential therapeutic transplantations.

Vascular pattern formation in plants.

PubMed

Scarpella, Enrico; Helariutta, Ykä

2010-01-01

Reticulate tissue systems exist in most multicellular organisms, and the principles underlying the formation of cellular networks have fascinated philosophers, mathematicians, and biologists for centuries. In particular, the beautiful and varied arrangements of vascular tissues in plants have intrigued mankind since antiquity, yet the organizing signals have remained elusive. Plant vascular tissues form systems of interconnected cell files throughout the plant body. Vascular cells are aligned with one another along continuous lines, and vascular tissues differentiate at reproducible positions within organ environments. However, neither the precise path of vascular differentiation nor the exact geometry of vascular networks is fixed or immutable. Several recent advances converge to reconcile the seemingly conflicting predictability and plasticity of vascular tissue patterns. A control mechanism in which an apical-basal flow of signal establishes a basic coordinate system for body axis formation and vascular strand differentiation, and in which a superimposed level of radial organizing cues elaborates cell patterns, would generate a reproducible tissue configuration in the context of an underlying robust, self-organizing structure, and account for the simultaneous regularity and flexibility of vascular tissue patterns. Copyright 2010 Elsevier Inc. All rights reserved.

The impact of various scaffold components on vascularized bone constructs.

PubMed

Eweida, Ahmad; Schulte, Matthias; Frisch, Oliver; Kneser, Ulrich; Harhaus, Leila

2017-06-01

Bone tissue engineering is gaining more interest in the field of craniofacial surgery where continuous efforts are being made to improve the outcomes via modulation of the scaffold components. In an in vitro three dimensional (3D) culture, the effect of bone morphogenic protein 2 (BMP2, 60 μg/ml) and the effect of different cell seeding densities (0.25, 0.5, and 1 × 104) of rat mesenchymal stem cells seeded on nanocrystalline hydroxyapatite in silica gel matrix (Nanobone ® ) on the cell viability and differentiation were studied. Alkaline phosphatase and viability assays were performed at day 7, day 14, and day 21 to assess the differentiation and the relative fraction of viable cells in the 3D cell cultures. In a subsequent in vivo study, we examined the effect of axial vascularization, the scaffold's particle size and the nature of the matrix (collagen type I vs. diluted fibrin) on vascularization and tissue generation in vascularized bone construct in rats. Regarding vascularization, we compared constructs vascularized randomly by extrinsic vascularization from the periphery of the implanted construct with others vascularized axially via an implanted arteriovenous loop (AVL). Regarding the particle size, we compared constructs having a scaffold particle size of 0.2 mm (powder) with other constructs having a particle size of 2 × 0.6 mm (granules). Regarding the matrix we compared constructs having a collagen matrix with others having a fibrin matrix. Various groups were compared regarding the amount of tissue generation, vascularization, and cellular proliferation. The initial seeding density had a temporary and minimal effect on the overall osteogenic differentiation of the cells. On the contrary, adding BMP2 in a concentration of 60 μg/ml over one week led to an overall enhanced osteogenic differentiation despite depressed cell viability. Axial vascularization was mandatory for efficient tissue formation and vascularization of the bone construct. Collagen matrix and a smaller particle size provided more favorable results in terms of vascularization and tissue formation than diluted fibrin and larger Nanobone particles. Copyright © 2017 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Tissue-engineered vascular grafts for use in the treatment of congenital heart disease: from the bench to the clinic and back again.

PubMed

Patterson, Joseph T; Gilliland, Thomas; Maxfield, Mark W; Church, Spencer; Naito, Yuji; Shinoka, Toshiharu; Breuer, Christopher K

2012-05-01

Since the first tissue-engineered vascular graft (TEVG) was implanted in a child over a decade ago, growth in the field of vascular tissue engineering has been driven by clinical demand for improved vascular prostheses with performance and durability similar to an autologous blood vessel. Great strides were made in pediatric congenital heart surgery using the classical tissue engineering paradigm, and cell seeding of scaffolds in vitro remained the cornerstone of neotissue formation. Our second-generation bone marrow cell-seeded TEVG diverged from tissue engineering dogma with a design that induces the recipient to regenerate vascular tissue in situ. New insights suggest that neovessel development is guided by cell signals derived from both seeded cells and host inflammatory cells that infiltrate the graft. The identification of these signals and the regulatory interactions that influence cell migration, phenotype and extracellular matrix deposition during TEVG remodeling are yielding a next-generation TEVG engineered to guide neotissue regeneration without the use of seeded cells. These developments represent steady progress towards our goal of an off-the-shelf tissue-engineered vascular conduit for pediatric congenital heart surgery.

Efficient Direct Reprogramming of Mature Amniotic Cells into Endothelial Cells by ETS Factors and TGFβ Suppression

PubMed Central

Ginsberg, Michael; James, Daylon; Ding, Bi-Sen; Nolan, Daniel; Geng, Fuqiang; Butler, Jason M; Schachterle, William; Pulijaal, Venkat R; Mathew, Susan; Chasen, Stephen T; Xiang, Jenny; Rosenwaks, Zev; Shido, Koji; Elemento, Olivier; Rabbany, Sina Y; Rafii, Shahin

2012-01-01

ETS transcription factors ETV2, FLI1 and ERG1 specify pluripotent stem cells into endothelial cells (ECs). However, these ECs are unstable and drift towards non-vascular cell fates. We show that human mid-gestation c-Kit− lineage-committed amniotic cells (ACs) can be readily reprogrammed into induced vascular endothelial cells (iVECs). Transient ETV2 expression in ACs generated proliferative but immature iVECs, while co-expression with FLI1/ERG1 endowed iVECs with a vascular repertoire and morphology matching mature stable ECs. Brief TGFβ-inhibition functionalized VEGFR2 signaling, augmenting specification of ACs to iVECs. Genome-wide transcriptional analyses showed that iVECs are similar to adult ECs in which vascular-specific genes are turned on and non-vascular genes are silenced. Functionally, iVECs form long-lasting patent vasculature in Matrigel plugs and regenerating livers. Thus, short-term ETV2 expression and TGFβ-inhibition along with constitutive ERG1/FLI1 co-expression reprogram mature ACs into durable and functional iVECs with clinical-scale expansion potential. Public banking of HLA-typed iVECs would establish a vascular inventory for treatment of genetically diverse disorders. PMID:23084400

Design of biomimetic vascular grafts with magnetic endothelial patterning.

PubMed

Fayol, Delphine; Le Visage, Catherine; Ino, Julia; Gazeau, Florence; Letourneur, Didier; Wilhelm, Claire

2013-01-01

The development of small diameter vascular grafts with a controlled pluricellular organization is still needed for effective vascular tissue engineering. Here, we describe a technological approach combining a tubular scaffold and magnetically labeled cells to create a pluricellular and organized vascular graft, the endothelialization of which could be monitored by MRI prior to transplantation. A novel type of scaffold was developed with a tubular geometry and a porous bulk structure enabling the seeding of cells in the scaffold pores. A homogeneous distribution of human mesenchymal stem cells in the macroporous structure was obtained by seeding the freeze-dried scaffold with the cell suspension. The efficient covering of the luminal surface of the tube was then made possible thanks to the implementation of a magnetic-based patterning technique. Human endothelial cells or endothelial progenitors were magnetically labeled with iron oxide nanoparticles and successfully attracted to the 2-mm lumen where they attached and formed a continuous endothelium. The combination of imaging modalities [fluorescence imaging, histology, and 3D magnetic resonance imaging (MRI)] evidenced the integrity of the vascular construct. In particular, the observation of different cell organizations in a vascular scaffold within the range of resolution of single cells by 4.7 T MRI is reported.

Redox-dependent impairment of vascular function in sickle cell disease.

PubMed

Aslan, Mutay; Freeman, Bruce A

2007-12-01

The vascular pathophysiology of sickle cell disease (SCD) is influenced by many factors, including adhesiveness of red and white blood cells to endothelium, increased coagulation, and homeostatic perturbation. The vascular endothelium is central to disease pathogenesis because it displays adhesion molecules for blood cells, balances procoagulant and anticoagulant properties of the vessel wall, and regulates vascular homeostasis by synthesizing vasoconstricting and vasodilating substances. The occurrence of intermittent vascular occlusion in SCD leads to reperfusion injury associated with granulocyte accumulation and enhanced production of reactive oxygen species. The participation of nitric oxide (NO) in oxidative reactions causes a reduction in NO bioavailability and contributes to vascular dysfunction in SCD. Therapeutic strategies designed to counteract endothelial, inflammatory, and oxidative abnormalities may reduce the frequency of hospitalization and blood transfusion, the incidence of pain, and the occurrence of acute chest syndrome and pulmonary hypertension in patients with SCD.

A natural protective mechanism against hyperglycaemia in vascular endothelial and smooth-muscle cells: role of glucose and 12-hydroxyeicosatetraenoic acid.

PubMed Central

Alpert, Evgenia; Gruzman, Arie; Totary, Hanan; Kaiser, Nurit; Reich, Reuven; Sasson, Shlomo

2002-01-01

Bovine aortic endothelial and smooth-muscle cells down-regulate the rate of glucose transport in the face of hyperglycaemia, thus providing protection against deleterious effects of increased intracellular glucose levels. When exposed to high glucose concentrations these cells reduced the mRNA and protein content of their typical glucose transporter, GLUT-1, as well as its plasma-membrane abundance. Inhibition of the lipoxygenase (LO) pathway, and particularly 12-LO, reversed this glucose-induced down-regulatory process and restored the rate of hexose transport to the level seen in vascular cells exposed to normal glucose levels. This reversal was accompanied by increased levels of GLUT-1 mRNA and protein, as well as of its plasma-membrane content. Exposure of the vascular cells to elevated glucose concentrations increased by 2-3-fold the levels of cell-associated and secreted 12-hydroxyeicosatetraenoic acid (12-HETE), the product of 12-LO. Inhibition of 15- and 5-LO, cyclo-oxygenases 1 and 2, and eicosanoid-producing cytochrome P450 did not modify the hexose-transport system in vascular cells. These results suggest a role for HETEs in the autoregulation of hexose transport in vascular cells. 8-Iso prostaglandin F(2alpha), a non-enzymic oxidation product of arachidonic acid, had no effect on the hexose-transport system in vascular cells exposed to hyperglycaemic conditions. Taken together, these findings show that hyperglycaemia increases the production rate of 12-HETE, which in turn mediates the down-regulation of GLUT-1 expression and the glucose-transport system in vascular endothelial and smooth-muscle cells. PMID:11853550

The force-sensing device region of α-catenin is an intrinsically disordered segment in the absence of intramolecular stabilization of the autoinhibitory form.

PubMed

Hirano, Yoshinori; Amano, Yu; Yonemura, Shigenobu; Hakoshima, Toshio

2018-05-01

Mechanotransduction by α-catenin facilitates the force-dependent development of adherens junctions (AJs) by recruiting vinculin to reinforce actin anchoring of AJs. The α-catenin mechanotransducing action is facilitated by its force-sensing device region that autoinhibits the vinculin-binding site 1 (VBS1). Here, we report the high-resolution structure of the force-sensing device region of α-catenin, which shows the autoinhibited form comprised of helix bundles E, F and G. The cryptic VBS1 is embedded into helix bundle E stabilized by direct interactions with the autoinhibitory region forming helix bundles F and G. Our molecular dissection study showed that helix bundles F and G are stable in solution in each isolated form, whereas helix bundle E that contains VBS1 is unstable and intrinsically disordered in solution in the isolated form. We successfully identified key residues mediating the autoinhibition and produced mutated α-catenins that display variable force sensitivity and autoinhibition. Using these mutants, we demonstrate both in vitro and in vivo that, in the absence of this stabilization, the helix bundle containing VBS1 would adopt an unfolded form, thus exposing VBS for vinculin binding. We provide evidence for importance of mechanotransduction with the intrinsic force sensitivity for vinculin recruitment to adherens junctions of epithelial cell sheets with mutated α-catenins. © 2018 Molecular Biology Society of Japan and John Wiley & Sons Australia, Ltd.

Structure and composition of pulmonary arteries, capillaries and veins

PubMed Central

2013-01-01

The pulmonary vasculature is comprised of three anatomic compartments connected in series: the arterial tree, an extensive capillary bed, and the venular tree. Although in general this vasculature is thin-walled, structure is nonetheless complex. Contributions to structure (and thus potentially to function) from cells other than endothelial and smooth muscle cells as well as those from the extracellular matrix should be considered. This review is multifaceted, bringing together information regarding 1) classification of pulmonary vessels, 2) branching geometry in the pulmonary vascular tree, 3) a quantitative view of structure based on morphometry of the vascular wall, 4) the relationship of nerves, a variety of interstitial cells, matrix proteins, and striated myocytes to smooth muscle and endothelium in the vascular wall, 5) heterogeneity within cell populations and between vascular compartments, 6) homo- and heterotypic cell-cell junctional complexes, and 7) the relation of the pulmonary vasculature to that of airways. These issues for pulmonary vascular structure are compared, when data is available, across species from human to mouse and shrew. Data from studies utilizing vascular casting, light and electron microscopy, as well as models developed from those data, are discussed. Finally, the need for rigorous quantitative approaches to study of vascular structure in lung is highlighted. PMID:23606929

Effect of reconstructive vascular surgery on red cell deformability--preliminary results.

PubMed Central

Irwin, S T; Rocks, M J; McGuigan, J A; Patterson, C C; Morris, T C; O'Reilly, M J

1983-01-01

Using a simple filtration method, red cell deformability was measured in healthy control subjects and in patients with peripheral vascular disease. Impaired red cell deformability was demonstrated in patients with rest pain or gangrene and in patients with intermittent claudication. An improvement in red cell deformability was demonstrated after successful reconstructive vascular surgery in both patient groups. An improvement in red cell deformability was demonstrated in patients undergoing major limb amputation. PMID:6619311

Light-enhanced dark respiration in leaves, isolated cells and protoplasts of various types of C4 plants.

PubMed

Parys, Eugeniusz; Jastrzebski, Hubert

2006-04-01

The rate of respiratory CO2 evolution from the leaves of Zea mays, Panicum miliaceum, and Panicum maximum, representing NADP-ME, NAD-ME, and PEP-CK types of C4 plants, respectively, was increased by approximately two to four times after a period of photosynthesis. This light-enhanced dark respiration (LEDR) was a function of net photosynthetic rate specific to plant species, and was depressed by 1% O2. When malate, aspartate, oxaloacetate or glycine solution at 50 mM concentration was introduced into the leaves instead of water, the rate of LEDR was enhanced, far less in Z. mays (by 10-25%) than in P. miliaceum (by 25-35%) or P. maximum (by 40-75%). The enhancement of LEDR under glycine was relatively stable over a period of 1 h, whereas the remaining metabolites caused its decrease following a transient increase. The metabolites reduced the net photosynthesis rate in the two Panicum species, but not in Z. mays, where this process was stimulated by glycine. The bundle sheath cells from P. miliaceum exhibited a higher rate of LEDR than those of Z. mays and P. maximum. Glycine had no effect on the respiration rate of the cells, but malate increased in cells of Z. mays and P. miliaceum by about 50% and 30%, respectively. With the exception of aspartate, which stimulated both the O2 evolution and O2 uptake in P. maximum, the remaining metabolites reduced photosynthetic O2 evolution from bundle sheath cells in Panicun species. The net O2 exchange in illuminated cells of Z. mays did not respond to CO2 or metabolites. Leaf mesophyll protoplasts of Z. mays and P. miliaceum, and bundle sheath protoplasts of Z. mays, which are unable to fix CO2 photosynthetically, also produced LEDR, but the mesophyll protoplasts, compared with bundle sheath protoplasts, required twice the time of illumination to obtain the maximal rate. The results suggest that the substrates for LEDR in C4 plants are generated during a period of illumination not only via the Calvin cycle reactions, but also by the conversion of endogenous compounds present in leaf cells. The stimulation of LEDR under glycine is discussed in relation to its direct or indirect effect on mitochondrial respiration.

Penetration and development of Meloidogyne arenaria on two new grape rootstocks.

PubMed

Anwar, Safdar A; McKenry, M V

2002-06-01

Penetration, development, and reproduction of a virulent 'Harmony' population of Meloidogyne arenaria was studied on two nematode-resistant grape rootstocks 10-17A and 6-19B. 'Cabernet Sauvignon' was used as a susceptible control for comparison. Plants were inoculated with 100 freshly hatched second-stage juveniles (J2) of M. arenaria. Greater numbers of J2 penetrated roots of 'Cabernet' than 10-17A, and none penetrated roots of 6-19B 4 days after inoculation (DAI). At 7 DAI, vermiform J2 advanced to sausage-shaped J2 in roots of 'Cabernet,' penetrated roots of 6-19B, and had egressed from roots of 10-17A. Resistant rootstocks expressed hypersensitive responses to penetrating J2 along the root epidermis, among the cortical cells, and along the differentiating vascular bundles. At 13 DAI, 68% of the J2 had attained globose stage in roots of 'Cabernet,' whereas there was no development of vermiform J2 in roots of the other two rootstocks. The nematodes reproduced only in roots of 'Cabernet.' Lack of development of J2 in roots of the two resistant grape rootstocks might be the result of a hypersensitive response to J2 feeding.

Correlations between axial stiffness and microstructure of a species of bamboo

PubMed Central

Mannan, Sayyad; Paul Knox, J.

2017-01-01

Bamboo is a ubiquitous monocotyledonous flowering plant and is a member of the true grass family Poaceae. In many parts of the world, it is widely used as a structural material especially in scaffolding and buildings. In spite of its wide use, there is no accepted methodology for standardizing a species of bamboo for a particular structural purpose. The task of developing structure–property correlations is complicated by the fact that bamboo is a hierarchical material whose structure at the nanoscopic level is not very well explored. However, we show that as far as stiffness is concerned, it is possible to obtain reliable estimates of important structural properties like the axial modulus from the knowledge of certain key elements of the microstructure. Stiffness of bamboo depends most sensitively on the size and arrangement of the fibre sheaths surrounding the vascular bundles and the arrangement of crystalline cellulose microfibrils in their secondary cell walls. For the species of bamboo studied in this work, we have quantitatively determined the radial gradation that the arrangement of fibres renders to the structure. The arrangement of the fibres gives bamboo a radially graded property variation across its cross section. PMID:28280545

Tolerance to Cadmium of Agave lechuguilla (Agavaceae) Seeds and Seedlings from Sites Contaminated with Heavy Metals

PubMed Central

Méndez-Hurtado, Alejandra; Rangel-Méndez, René; Flores, Joel

2013-01-01

We investigated if seeds of Agave lechuguilla from contaminated sites with heavy metals were more tolerant to Cd ions than seeds from noncontaminated sites. Seeds from a highly contaminated site (Villa de la Paz) and from a noncontaminated site (Villa de Zaragoza) were evaluated. We tested the effect of Cd concentrations on several ecophysiological, morphological, genetical, and anatomical responses. Seed viability, seed germination, seedling biomass, and radicle length were higher for the non-polluted site than for the contaminated one. The leaves of seedlings from the contaminated place had more cadmium and showed peaks attributed to chemical functional groups such as amines, amides, carboxyl, and alkenes that tended to disappear due to increasing the concentration of cadmium than those from Villa de Zaragoza. Malformed cells in the parenchyma surrounding the vascular bundles were found in seedlings grown with Cd from both sites. The leaves from the contaminated place showed a higher metallothioneins expression in seedlings from the control group than that of seedlings at different Cd concentrations. Most of our results fitted into the hypothesis that plants from metal-contaminated places do not tolerate more pollution, because of the accumulative effect that cadmium might have on them. PMID:24453802

Tolerance to cadmium of Agave lechuguilla (Agavaceae) seeds and seedlings from sites contaminated with heavy metals.

PubMed

Méndez-Hurtado, Alejandra; Rangel-Méndez, René; Yáñez-Espinosa, Laura; Flores, Joel

2013-01-01

We investigated if seeds of Agave lechuguilla from contaminated sites with heavy metals were more tolerant to Cd ions than seeds from noncontaminated sites. Seeds from a highly contaminated site (Villa de la Paz) and from a noncontaminated site (Villa de Zaragoza) were evaluated. We tested the effect of Cd concentrations on several ecophysiological, morphological, genetical, and anatomical responses. Seed viability, seed germination, seedling biomass, and radicle length were higher for the non-polluted site than for the contaminated one. The leaves of seedlings from the contaminated place had more cadmium and showed peaks attributed to chemical functional groups such as amines, amides, carboxyl, and alkenes that tended to disappear due to increasing the concentration of cadmium than those from Villa de Zaragoza. Malformed cells in the parenchyma surrounding the vascular bundles were found in seedlings grown with Cd from both sites. The leaves from the contaminated place showed a higher metallothioneins expression in seedlings from the control group than that of seedlings at different Cd concentrations. Most of our results fitted into the hypothesis that plants from metal-contaminated places do not tolerate more pollution, because of the accumulative effect that cadmium might have on them.

In Vitro Endothelialization of Biodegradable Vascular Grafts Via Endothelial Progenitor Cell Seeding and Maturation in a Tubular Perfusion System Bioreactor.

PubMed

Melchiorri, Anthony J; Bracaglia, Laura G; Kimerer, Lucas K; Hibino, Narutoshi; Fisher, John P

2016-07-01

A critical challenge to the success of biodegradable vascular grafts is the establishment of a healthy endothelium. To establish this monolayer of endothelial cells (ECs), a variety of techniques have been developed, including cell seeding. Vascular grafts may be seeded with relevant cell types and allowed to mature before implantation. Due to the low proliferative ability of adult ECs and issues with donor site morbidity, there has been increasing interest in using endothelial progenitor cells (EPCs) for vascular healing procedures. In this work, we combined the proliferative and differentiation capabilities of a commercial cell line of early EPCs with an established bioreactor system to support the maturation of cell-seeded vascular grafts. All components of the vascular graft and bioreactor setup are commercially available and allow for complete customization of the scaffold and culturing system. This bioreactor setup enables the control of flow through the graft, imparting fluid shear stress on EPCs and affecting cellular proliferation and differentiation. Grafts cultured with EPCs in the bioreactor system demonstrated greatly increased cell populations and neotissue formation compared with grafts seeded and cultured in a static system. Increased expression of markers for mature endothelial tissues were also observed in bioreactor-cultured EPC-seeded grafts. These findings suggest the distinct advantages of a customizable bioreactor setup for the proliferation and maturation of EPCs. Such a strategy may be beneficial for utilizing EPCs in vascular tissue engineering applications.

Multiplexed salivary protein profiling for patients with respiratory diseases using fiber-optic bundles and fluorescent antibody-based microarrays.

PubMed

Nie, Shuai; Benito-Peña, Elena; Zhang, Huaibin; Wu, Yue; Walt, David R

2013-10-01

Over the past 40 years, the incidence and prevalence of respiratory diseases have increased significantly throughout the world, damaging economic productivity and challenging health care systems. Current diagnoses of different respiratory diseases generally involve invasive sampling methods such as induced sputum or bronchoalveolar lavage that are uncomfortable, or even painful, for the patient. In this paper, we present a platform incorporating fiber-optic bundles and antibody-based microarrays to perform multiplexed protein profiling of a panel of six salivary biomarkers for asthma and cystic fibrosis (CF) diagnosis. The platform utilizes an optical fiber bundle containing approximately 50,000 individual 4.5 μm diameter fibers that are chemically etched to create microwells in which modified microspheres decorated with monoclonal capture antibodies can be deposited. On the basis of a sandwich immunoassay format, the array quantifies human vascular endothelial growth factor (VEGF), interferon gamma-induced protein 10 (IP-10), interleukin-8 (IL-8), epidermal growth factor (EGF), matrix metalloproteinase 9 (MMP-9), and interleukin-1 beta (IL-1β) salivary biomarkers in the subpicomolar range. Saliva supernatants collected from 291 individuals (164 asthmatics, 71 CF patients, and 56 healthy controls (HC)) were analyzed on the platform to profile each group of patients using this six-analyte suite. It was found that four of the six proteins were observed to be significantly elevated (p < 0.01) in asthma and CF patients compared with HC. These results demonstrate the potential to use the multiplexed protein array platform for respiratory disease diagnosis.

Sox17 drives functional engraftment of endothelium converted from non-vascular cells.

PubMed

Schachterle, William; Badwe, Chaitanya R; Palikuqi, Brisa; Kunar, Balvir; Ginsberg, Michael; Lis, Raphael; Yokoyama, Masataka; Elemento, Olivier; Scandura, Joseph M; Rafii, Shahin

2017-01-16

Transplanting vascular endothelial cells (ECs) to support metabolism and express regenerative paracrine factors is a strategy to treat vasculopathies and to promote tissue regeneration. However, transplantation strategies have been challenging to develop, because ECs are difficult to culture and little is known about how to direct them to stably integrate into vasculature. Here we show that only amniotic cells could convert to cells that maintain EC gene expression. Even so, these converted cells perform sub-optimally in transplantation studies. Constitutive Akt signalling increases expression of EC morphogenesis genes, including Sox17, shifts the genomic targeting of Fli1 to favour nearby Sox consensus sites and enhances the vascular function of converted cells. Enforced expression of Sox17 increases expression of morphogenesis genes and promotes integration of transplanted converted cells into injured vessels. Thus, Ets transcription factors specify non-vascular, amniotic cells to EC-like cells, whereas Sox17 expression is required to confer EC function.

Tension is required for fibripositor formation.

PubMed

Kapacee, Zoher; Richardson, Susan H; Lu, Yinhui; Starborg, Tobias; Holmes, David F; Baar, Keith; Kadler, Karl E

2008-05-01

Embryonic tendon cells (ETCs) have actin-rich fibripositors that accompany parallel bundles of collagen fibrils in the extracellular matrix. To study fibripositor function, we have developed a three-dimensional cell culture system that promotes and maintains fibripositors. We show that ETCs cultured in fixed-length fibrin gels replace the fibrin during ~6 days in culture with parallel bundles of narrow-diameter collagen fibrils that are uniaxially aligned with fibripositors, thereby generating a tendon-like construct. Fibripositors occurred simultaneously with onset of parallel collagen fibrils. Interestingly, the constructs have a tendon-like crimp. In initial experiments to study the effects of tension, we showed that cutting the constructs resulted in loss of tension, loss of fibripositors and the appearance of immature fibrils with no preferred orientation.

Nrf2/Keap1 system regulates vascular smooth muscle cell apoptosis for vascular homeostasis: role in neointimal formation after vascular injury

PubMed Central

Ashino, Takashi; Yamamoto, Masayuki; Numazawa, Satoshi

2016-01-01

Abnormal increases in vascular smooth muscle cells (VSMCs) in the intimal region after a vascular injury is a key event in developing neointimal hyperplasia. To maintain vascular function, proliferation and apoptosis of VSMCs is tightly controlled during vascular remodeling. NF-E2-related factor 2 (Nrf2)/Kelch-like ECH-associated protein 1 (Keap1) system, a key component of the oxidative stress response that acts in maintaining homeostasis, plays an important role in neointimal hyperplasia after a vascular injury; however, the role of Nrf2/Keap1 in VSMC apoptosis has not been clarified. Here we report that 14 days after arterial injury in mice, TUNEL-positive VSMCs are detected in both the neointimal and medial layers. These layers contain cells expressing high levels of Nrf2 but low Keap1 expression. In VSMCs, Keap1 depletion induces features of apoptosis, such as positive TUNEL staining and annexin V binding. These changes are associated with an increased expression of nuclear Nrf2. Simultaneous Nrf2 depletion inhibits Keap1 depletion-induced apoptosis. At 14 days after the vascular injury, Nrf2-deficient mice demonstrated fewer TUNEL-positive cells and increased neointimal formation in the neointimal and medial areas. The results suggest that the Nrf2/Keap1 system regulates VSMC apoptosis during neointimal formation, thereby inhibiting neointimal hyperplasia after a vascular injury. PMID:27198574

Fascin 1 is an actin filament-bundling protein that regulates ectoplasmic specialization dynamics in the rat testis

PubMed Central

Gungor-Ordueri, N. Ece; Celik-Ozenci, Ciler

2014-01-01

In the testis, spermatids are polarized cells, with their heads pointing toward the basement membrane during maturation. This polarity is crucial to pack the maximal number of spermatids in the seminiferous epithelium so that millions of sperms can be produced daily. A loss of spermatid polarity is detected after rodents are exposed to toxicants (e.g., cadmium) or nonhormonal male contraceptives (e.g., adjudin), which is associated with a disruption on the expression and/or localization of polarity proteins. In the rat testis, fascin 1, an actin-bundling protein found in mammalian cells, was expressed by Sertoli and germ cells. Fascin 1 was a component of the ectoplasmic specialization (ES), a testis-specific anchoring junction known to confer spermatid adhesion and polarity. Its expression in the seminiferous epithelium was stage specific. Fascin 1 was localized to the basal ES at the Sertoli cell-cell interface of the blood-testis barrier in all stages of the epithelial cycle, except it diminished considerably at late stage VIII. Fascin 1 was highly expressed at the apical ES at stage VII–early stage VIII and restricted to the step 19 spermatids. Its knockdown by RNAi that silenced fascin 1 by ∼70% in Sertoli cells cultured in vitro was found to perturb the tight junction-permeability barrier via a disruption of F-actin organization. Knockdown of fascin 1 in vivo by ∼60–70% induced defects in spermatid polarity, which was mediated by a mislocalization and/or downregulation of actin-bundling proteins Eps8 and palladin, thereby impeding F-actin organization and disrupting spermatid polarity. In summary, these findings provide insightful information on spermatid polarity regulation. PMID:25159326

The cell wall of Arabidopsis thaliana influences actin network dynamics.

PubMed

Tolmie, Frances; Poulet, Axel; McKenna, Joseph; Sassmann, Stefan; Graumann, Katja; Deeks, Michael; Runions, John

2017-07-20

In plant cells, molecular connections link the cell wall-plasma membrane-actin cytoskeleton to form a continuum. It is hypothesized that the cell wall provides stable anchor points around which the actin cytoskeleton remodels. Here we use live cell imaging of fluorescently labelled marker proteins to quantify the organization and dynamics of the actin cytoskeleton and to determine the impact of disrupting connections within the continuum. Labelling of the actin cytoskeleton with green fluorescent protein (GFP)-fimbrin actin-binding domain 2 (FABD2) resulted in a network composed of fine filaments and thicker bundles that appeared as a highly dynamic remodelling meshwork. This differed substantially from the GFP-Lifeact-labelled network that appeared much more sparse with thick bundles that underwent 'simple movement', in which the bundles slightly change position, but in such a manner that the structure of the network was not substantially altered during the time of observation. Label-dependent differences in actin network morphology and remodelling necessitated development of two new image analysis techniques. The first of these, 'pairwise image subtraction', was applied to measurement of the more rapidly remodelling actin network labelled with GFP-FABD2, while the second, 'cumulative fluorescence intensity', was used to measure bulk remodelling of the actin cytoskeleton when labelled with GFP-Lifeact. In each case, these analysis techniques show that the actin cytoskeleton has a decreased rate of bulk remodelling when the cell wall-plasma membrane-actin continuum is disrupted either by plasmolysis or with isoxaben, a drug that specifically inhibits cellulose deposition. Changes in the rate of actin remodelling also affect its functionality, as observed by alteration in Golgi body motility. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Smooth muscle architecture within cell-dense vascular tissues influences functional contractility.

PubMed

Win, Zaw; Vrla, Geoffrey D; Steucke, Kerianne E; Sevcik, Emily N; Hald, Eric S; Alford, Patrick W

2014-12-01

The role of vascular smooth muscle architecture in the function of healthy and dysfunctional vessels is poorly understood. We aimed at determining the relationship between vascular smooth muscle architecture and contractile output using engineered vascular tissues. We utilized microcontact printing and a microfluidic cell seeding technique to provide three different initial seeding conditions, with the aim of influencing the cellular architecture within the tissue. Cells seeded in each condition formed confluent and aligned tissues but within the tissues, the cellular architecture varied. Tissues with a more elongated cellular architecture had significantly elevated basal stress and produced more contractile stress in response to endothelin-1 stimulation. We also found a correlation between the contractile phenotype marker expression and the cellular architecture, contrary to our previous findings in non-confluent tissues. Taken with previous results, these data suggest that within cell-dense vascular tissues, smooth muscle contractility is strongly influenced by cell and tissue architectures.

Vasculature on the clock: Circadian rhythm and vascular dysfunction.

PubMed

Crnko, Sandra; Cour, Martin; Van Laake, Linda W; Lecour, Sandrine

2018-05-17

The master mammalian circadian clock (i.e. central clock), located in the suprachiasmatic nucleus of the hypothalamus, orchestrates the synchronization of the daily behavioural and physiological rhythms to better adapt the organism to the external environment in an anticipatory manner. This central clock is entrained by a variety of signals, the best established being light and food. However, circadian cycles are not simply the consequences of these two cues but are generated by endogenous circadian clocks. Indeed, clock machinery is found in mainly all tissues and cell types, including cells of the vascular system such as endothelial cells, fibroblasts, smooth muscle cells and stem cells. This machinery physiologically contributes to modulate the daily vascular function, and its disturbance therefore plays a major role in the pathophysiology of vascular dysfunction. Therapies targeting the circadian rhythm may therefore be of benefit against vascular disease. Copyright © 2018 Elsevier Inc. All rights reserved.