Systems and Photosystems: Cellular Limits of Autotrophic Productivity in Cyanobacteria

PubMed Central

Burnap, Robert L.

2014-01-01

Recent advances in the modeling of microbial growth and metabolism have shown that growth rate critically depends upon the optimal allocation of finite proteomic resources among different cellular functions and that modeling growth rates becomes more realistic with the explicit accounting for the costs of macromolecular synthesis, most importantly, protein expression. The “proteomic constraint” is considered together with its application to understanding photosynthetic microbial growth. The central hypothesis is that physical limits of cellular space (and corresponding solvation capacity) in conjunction with cell surface-to-volume ratios represent the underlying constraints on the maximal rate of autotrophic microbial growth. The limitation of cellular space thus constrains the size the total complement of macromolecules, dissolved ions, and metabolites. To a first approximation, the upper limit in the cellular amount of the total proteome is bounded this space limit. This predicts that adaptation to osmotic stress will result in lower maximal growth rates due to decreased cellular concentrations of core metabolic proteins necessary for cell growth owing the accumulation of compatible osmolytes, as surmised previously. The finite capacity of membrane and cytoplasmic space also leads to the hypothesis that the species-specific differences in maximal growth rates likely reflect differences in the allocation of space to niche-specific proteins with the corresponding diminution of space devoted to other functions including proteins of core autotrophic metabolism, which drive cell reproduction. An optimization model for autotrophic microbial growth, the autotrophic replicator model, was developed based upon previous work investigating heterotrophic growth. The present model describes autotrophic growth in terms of the allocation protein resources among core functional groups including the photosynthetic electron transport chain, light-harvesting antennae, and the

Effect of Inhibition of Deoxyribonucleic Acid and Protein Synthesis on the Direction of Cell Wall Growth in Streptococcus faecalis

PubMed Central

Higgins, M. L.; Daneo-Moore, L.; Boothby, D.; Shockman, G. D.

1974-01-01

Selective inhibition of protein synthesis in Streptococcus faecalis (ATCC 9790) was accompanied by a rapid and severe inhibition of cell division and a reduction of enlargement of cellular surface area. Continued synthesis of cell wall polymers resulted in rapid thickening of the wall to an extent not seen in exponential-phase populations. Thus, the normal direction of wall growth was changed from a preferential feeding out of new wall surface to that of thickening existing cell surfaces. However, the overall manner in which the wall thickened, from nascent septa toward polar regions, was the same in both exponential-phase and inhibited populations. In contrast, selective inhibition of deoxyribonucleic acid (DNA) synthesis using mitomycin C was accompanied by an increase in cellular surface area and by division of about 80% of the cells in random populations. Little or no wall thickening was observed until the synthesis of macromolecules other than DNA was impaired and further cell division ceased. Concomitant inhibition of both DNA and protein synthesis inhibited cell division but permitted an increase in average cell volume. In such doubly inhibited cells, walls thickened less than in cells inhibited for protein synthesis only. On the basis of the results obtained, a model for cell surface enlargement and cell division is presented. The model proposes that: (i) each wall enlargement site is influenced by an individual chromosome replication cycle; (ii) during chromosome replication peripheral surface enlargement would be favored over thickening (or septation); (iii) a signal associated with chromosome termination would favor thickening (and septation) at the expense of surface enlargement; and (iv) a factor or signal related to protein synthesis would be required for one or more of the near terminal stages of cell division or cell separation, or both. Images PMID:4133352

Transparent metal model study of the use of a cellular growth front to form aligned monotectic composite materials

NASA Technical Reports Server (NTRS)

Kaukler, William F.

1988-01-01

The purpose of this work was to resolve a scientific controversy in the understanding of how second phase particles become aligned during unidirectional growth of a monotectic alloy. A second aspect was to make the first systematic observations of the solidification behavior of a monotectic alloy during cellular growth in-situ. This research provides the first systematic transparent model study of cellular solidification. An interface stability diagram was developed for the planar to cellular transition of the succinonitrile glycerol (SNG) system. A method was developed utilizing Fourier Transform Infrared Spectroscopy which allows quantitative compositional analysis of directionally solidified SNG along the growth axis. To determine the influence of cellular growth front on alignment for directionally solidified monotectic alloys, the planar and cellular growth morphology was observed in-situ for SNG between 8 and 17 percent glycerol and for a range of over two orders of magnitude G/R.

A Compact Synchronous Cellular Model of Nonlinear Calcium Dynamics: Simulation and FPGA Synthesis Results.

PubMed

Soleimani, Hamid; Drakakis, Emmanuel M

2017-06-01

Recent studies have demonstrated that calcium is a widespread intracellular ion that controls a wide range of temporal dynamics in the mammalian body. The simulation and validation of such studies using experimental data would benefit from a fast large scale simulation and modelling tool. This paper presents a compact and fully reconfigurable cellular calcium model capable of mimicking Hopf bifurcation phenomenon and various nonlinear responses of the biological calcium dynamics. The proposed cellular model is synthesized on a digital platform for a single unit and a network model. Hardware synthesis, physical implementation on FPGA, and theoretical analysis confirm that the proposed cellular model can mimic the biological calcium behaviors with considerably low hardware overhead. The approach has the potential to speed up large-scale simulations of slow intracellular dynamics by sharing more cellular units in real-time. To this end, various networks constructed by pipelining 10 k to 40 k cellular calcium units are compared with an equivalent simulation run on a standard PC workstation. Results show that the cellular hardware model is, on average, 83 times faster than the CPU version.

A High-Performance Cellular Automaton Model of Tumor Growth with Dynamically Growing Domains

PubMed Central

Poleszczuk, Jan; Enderling, Heiko

2014-01-01

Tumor growth from a single transformed cancer cell up to a clinically apparent mass spans many spatial and temporal orders of magnitude. Implementation of cellular automata simulations of such tumor growth can be straightforward but computing performance often counterbalances simplicity. Computationally convenient simulation times can be achieved by choosing appropriate data structures, memory and cell handling as well as domain setup. We propose a cellular automaton model of tumor growth with a domain that expands dynamically as the tumor population increases. We discuss memory access, data structures and implementation techniques that yield high-performance multi-scale Monte Carlo simulations of tumor growth. We discuss tumor properties that favor the proposed high-performance design and present simulation results of the tumor growth model. We estimate to which parameters the model is the most sensitive, and show that tumor volume depends on a number of parameters in a non-monotonic manner. PMID:25346862

Protein accounting in the cellular economy.

PubMed

Vázquez-Laslop, Nora; Mankin, Alexander S

2014-04-24

Knowing the copy number of cellular proteins is critical for understanding cell physiology. By being able to measure the absolute synthesis rates of the majority of cellular proteins, Li et al. gain insights into key aspects of translation regulation and fundamental principles of cellular strategies to adjust protein synthesis according to the functional needs. Copyright © 2014 Elsevier Inc. All rights reserved.

Interactions of cytokines, growth factors, and the extracellular matrix in the cellular biology of uterine leiomyomata.

PubMed

Sozen, Ibrahim; Arici, Aydin

2002-07-01

To review the available information regarding the role of cytokines, growth factors, and the extracellular matrix in the pathophysiology of uterine leiomyomata and to integrate this information in a suggested model of disease at the cellular level. A thorough literature and MEDLINE search was conducted to identify the relevant studies in the English literature published between January, 1966 and October, 2001. A model of disease at the cellular level was developed using the most likely cytokines to be involved in the pathogenesis of leiomyomata as determined by our assessment of the available literature. A number of cytokines and growth factors, including transforming growth factor-beta (TGF-beta), epidermal growth factor, monocyte chemotactic protein-1, insulin-like growth factors 1 and 2, prolactin, parathyroid-hormone-related peptide, basic fibroblast growth factor, platelet-derived growth factor, interleukin-8, and endothelin, have been investigated in myometrium and leiomyoma. Among these cytokines, TGF-beta appears to be the only growth factor that has been shown to be overexpressed in leiomyoma vs. myometrium, be hormonally-regulated both in vivo and in vitro, and be both mitogenic and fibrogenic in these tissues. In addition to the cytokines, extracellular matrix components such as collagen, fibronectin, proteoglycans, matrix metalloproteinases, and tissue inhibitors of metalloproteinases seem to play pivotal roles in the pathogenesis of leiomyomata. We believe that, given the extent and depth of the current research on the cellular biology of leiomyomata, the cellular mechanisms responsible in the pathogenesis of leiomyomata will be identified clearly within the foreseeable future. This will enable researchers to develop therapy directed against the molecules and mechanisms at the cellular level.

Transient regulation of protein synthesis in Escherichia coli upon shift-up of growth temperature.

PubMed

Yamamori, T; Ito, K; Nakamura, Y; Yura, T

1978-06-01

Synthesis of total cellular proteins of Escherichia coli was studied upon transfer of a log-phase culture from 30 (or 37) to 42 degrees C. Cells were pulse-labeled with [3H]leucine, and the labeled proteins were analyzed by gel electrophoresis in the presence of sodium dodecyl sulfate. The rates of synthesis of at least five protein chains were found to increase markedly (5- to 10-fold) within 5 min after temperature shift-up and gradually decrease to the new steady-state levels, in contrast to the majority of proteins which gradually increase to the steady-state levels (about 1.5-fold the rate at 30 degrees C). Temperature shift-down did not cause any appreciable changes in the pattern of protein synthesis as detected by the present method. Among the proteins greatly affected by the temperature shift-up were those with apparent molecular weights fo 87,000 (87K), 76K, 73K, 64K, and 61K. Two of them (64K and 61K) were found to be precipitated with specific antiserum against proteins that had previously been shown to have an adenosine triphosphatase activity. The bearings of these findings on bacterial adaptation to variation in growth temperature are discussed.

Salinity and temperature variations reflecting on cellular PCNA, IGF-I and II expressions, body growth and muscle cellularity of a freshwater fish larvae.

PubMed

Martins, Y S; Melo, R M C; Campos-Junior, P H A; Santos, J C E; Luz, R K; Rizzo, E; Bazzoli, N

2014-06-01

The present study assessed the influence of salinity and temperature on body growth and on muscle cellularity of Lophiosilurus alexaxdri vitelinic larvae. Slightly salted environments negatively influenced body growth of freshwater fish larvae and we observed that those conditions notably act as an environmental influencer on muscle growth and on local expression of hypertrophia and hypeplasia markers (IGFs and PCNA). Furthermore, we could see that salinity tolerance for NaCl 4gl(-)(1) diminishes with increasing temperature, evidenced by variation in body and muscle growth, and by irregular morphology of the lateral skeletal muscle of larvae. We saw that an increase of both PCNA and autocrine IGF-II are correlated to an increase in fibre numbers and fibre diameter as the temperature increases and salinity diminishes. On the other hand, autocrine IGF-I follows the opposite way to the other biological parameters assessed, increasing as salinity increases and temperature diminishes, showing that this protein did not participate in muscle cellularity, but participating in molecular/cellular repair. Therefore, slightly salted environments may provide adverse conditions that cause some obstacles to somatic growth of this species, suggesting some osmotic expenditure with a salinity increment. Copyright © 2014 Elsevier Inc. All rights reserved.

Effect of high electromagnetic fields on cellular growth

NASA Astrophysics Data System (ADS)

Albalawi, Abdullah; Mustafa, Mohammed; Masood, Samina

It is already known that high-intensity electromagnetic field affect the human lung growth and forces the T-cells to decrease by 20-30 percent. The electromagnetic field had a severe impact on human T-cells in contrast to lung cells. Due to the high-intensity electromagnetic field, the growth of T-cells becomes low and release of Ca+2 increases up to 3.5 times more than the lung cells. The high-intensity electromagnetic radiations do not directly produce cancer cells but had a severe impact on the growth of T-cells. It can also be said that electromagnetic field acts a role in the cancer initiation. It creates disordered in the structure of membranes and gesture transduction. The higher exposure to electromagnetic field increases PKC-alpha and this larger release from membranes cannot be controlled. It was concluded that greater exposure to the electromagnetic field is dangerous and had a severe impact on T-cells growth and lung cells growth and due to this greater possibility of leukemia occurrence. We show a similar effect of electromagnetic fields single celled bacteria to compare the bacterial cellular growth with the human cells using the bacteria strains which are commonly found in human body.

Epidermal Growth Factor Enhances Cellular Uptake of Polystyrene Nanoparticles by Clathrin-Mediated Endocytosis

PubMed Central

Phuc, Le Thi Minh; Taniguchi, Akiyoshi

2017-01-01

The interaction between nanoparticles and cells has been studied extensively, but most research has focused on the effect of various nanoparticle characteristics, such as size, morphology, and surface charge, on the cellular uptake of nanoparticles. In contrast, there have been very few studies to assess the influence of cellular factors, such as growth factor responses, on the cellular uptake efficiency of nanoparticles. The aim of this study was to clarify the effects of epidermal growth factor (EGF) on the uptake efficiency of polystyrene nanoparticles (PS NPs) by A431 cells, a human carcinoma epithelial cell line. The results showed that EGF enhanced the uptake efficiency of A431 cells for PS NPs. In addition, inhibition and localization studies of PS NPs and EGF receptors (EGFRs) indicated that cellular uptake of PS NPs is related to the binding of EGF–EGFR complex and PS NPs. Different pathways are used to enter the cells depending on the presence or absence of EGF. In the presence of EGF, cellular uptake of PS NPs is via clathrin-mediated endocytosis, whereas, in the absence of EGF, uptake of PS NPs does not involve clathrin-mediated endocytosis. Our findings indicate that EGF enhances cellular uptake of PS NPs by clathrin-mediated endocytosis. This result could be important for developing safe nanoparticles and their safe use in medical applications. PMID:28629179

Epidermal Growth Factor Enhances Cellular Uptake of Polystyrene Nanoparticles by Clathrin-Mediated Endocytosis.

PubMed

Phuc, Le Thi Minh; Taniguchi, Akiyoshi

2017-06-19

The interaction between nanoparticles and cells has been studied extensively, but most research has focused on the effect of various nanoparticle characteristics, such as size, morphology, and surface charge, on the cellular uptake of nanoparticles. In contrast, there have been very few studies to assess the influence of cellular factors, such as growth factor responses, on the cellular uptake efficiency of nanoparticles. The aim of this study was to clarify the effects of epidermal growth factor (EGF) on the uptake efficiency of polystyrene nanoparticles (PS NPs) by A431 cells, a human carcinoma epithelial cell line. The results showed that EGF enhanced the uptake efficiency of A431 cells for PS NPs. In addition, inhibition and localization studies of PS NPs and EGF receptors (EGFRs) indicated that cellular uptake of PS NPs is related to the binding of EGF-EGFR complex and PS NPs. Different pathways are used to enter the cells depending on the presence or absence of EGF. In the presence of EGF, cellular uptake of PS NPs is via clathrin-mediated endocytosis, whereas, in the absence of EGF, uptake of PS NPs does not involve clathrin-mediated endocytosis. Our findings indicate that EGF enhances cellular uptake of PS NPs by clathrin-mediated endocytosis. This result could be important for developing safe nanoparticles and their safe use in medical applications.

Simulation of interdiffusion and voids growth based on cellular automata

NASA Astrophysics Data System (ADS)

Zhang, Fan; Zhang, Boyan; Zhang, Nan; Du, Haishun; Zhang, Xinhong

2017-02-01

In the interdiffusion of two solid-state materials, if the diffusion coefficients of the two materials are not the same, the interface of the two materials will shift to the material with the lower diffusion coefficient. This effect is known as the Kirkendall effect. The Kirkendall effect leads to Kirkendall porosity. The pores act as sinks for vacancies and become voids. In this paper, the movement of the Kirkendall plane at interdiffusion is simulated based on cellular automata. The number of vacancies, the critical radius of voids nucleation and the nucleation rate are analysed. The vacancies diffusion, vacancies aggregation and voids growth are also simulated based on cellular automata.

Quantifying the entropic cost of cellular growth control

NASA Astrophysics Data System (ADS)

De Martino, Daniele; Capuani, Fabrizio; De Martino, Andrea

2017-07-01

Viewing the ways a living cell can organize its metabolism as the phase space of a physical system, regulation can be seen as the ability to reduce the entropy of that space by selecting specific cellular configurations that are, in some sense, optimal. Here we quantify the amount of regulation required to control a cell's growth rate by a maximum-entropy approach to the space of underlying metabolic phenotypes, where a configuration corresponds to a metabolic flux pattern as described by genome-scale models. We link the mean growth rate achieved by a population of cells to the minimal amount of metabolic regulation needed to achieve it through a phase diagram that highlights how growth suppression can be as costly (in regulatory terms) as growth enhancement. Moreover, we provide an interpretation of the inverse temperature β controlling maximum-entropy distributions based on the underlying growth dynamics. Specifically, we show that the asymptotic value of β for a cell population can be expected to depend on (i) the carrying capacity of the environment, (ii) the initial size of the colony, and (iii) the probability distribution from which the inoculum was sampled. Results obtained for E. coli and human cells are found to be remarkably consistent with empirical evidence.

Inflating bacterial cells by increased protein synthesis

PubMed Central

Basan, Markus; Zhu, Manlu; Dai, Xiongfeng; Warren, Mya; Sévin, Daniel; Wang, Yi-Ping; Hwa, Terence

2015-01-01

Understanding how the homeostasis of cellular size and composition is accomplished by different organisms is an outstanding challenge in biology. For exponentially growing Escherichia coli cells, it is long known that the size of cells exhibits a strong positive relation with their growth rates in different nutrient conditions. Here, we characterized cell sizes in a set of orthogonal growth limitations. We report that cell size and mass exhibit positive or negative dependences with growth rate depending on the growth limitation applied. In particular, synthesizing large amounts of “useless” proteins led to an inversion of the canonical, positive relation, with slow growing cells enlarged 7- to 8-fold compared to cells growing at similar rates under nutrient limitation. Strikingly, this increase in cell size was accompanied by a 3- to 4-fold increase in cellular DNA content at slow growth, reaching up to an amount equivalent to ∼8 chromosomes per cell. Despite drastic changes in cell mass and macromolecular composition, cellular dry mass density remained constant. Our findings reveal an important role of protein synthesis in cell division control. PMID:26519362

Effects of sound exposure on the growth and intracellular macromolecular synthesis of E. coli k-12

PubMed Central

Zhang, Yongzhu; Wu, Ying

2016-01-01

Microbes, as one of the primary producers of the biosphere, play an important role in ecosystems. Exploring the mechanism of adaptation and resistance of microbial population to various environmental factors has come into focus in the fields of modern microbial ecology and molecular ecology. However, facing the increasingly serious problem of acoustic pollution, very few efforts have been put forth into studying the relation of single cell organisms and sound field exposure. Herein, we studied the biological effects of sound exposure on the growth of E. coli K-12 with different acoustic parameters. The effects of sound exposure on the intracellular macromolecular synthesis and cellular morphology of E. coli K-12 were also analyzed and discussed. Experimental results indicated that E. coli K-12 exposed to sound waves owned a higher biomass and a faster specific growth rate compared to the control group. Also, the average length of E. coli K-12 cells increased more than 27.26%. The maximum biomass and maximum specific growth rate of the stimulation group by 8000 Hz, 80dB sound wave was about 1.7 times and 2.5 times that of the control group, respectively. Moreover, it was observed that E. coli K-12 can respond rapidly to sound stress at both the transcriptional and posttranscriptional levels by promoting the synthesis of intracellular RNA and total protein. Some potential mechanisms may be involved in the responses of bacterial cells to sound stress. PMID:27077011

Effects of sound exposure on the growth and intracellular macromolecular synthesis of E. coli k-12.

PubMed

Gu, Shaobin; Zhang, Yongzhu; Wu, Ying

2016-01-01

Microbes, as one of the primary producers of the biosphere, play an important role in ecosystems. Exploring the mechanism of adaptation and resistance of microbial population to various environmental factors has come into focus in the fields of modern microbial ecology and molecular ecology. However, facing the increasingly serious problem of acoustic pollution, very few efforts have been put forth into studying the relation of single cell organisms and sound field exposure. Herein, we studied the biological effects of sound exposure on the growth of E. coli K-12 with different acoustic parameters. The effects of sound exposure on the intracellular macromolecular synthesis and cellular morphology of E. coli K-12 were also analyzed and discussed. Experimental results indicated that E. coli K-12 exposed to sound waves owned a higher biomass and a faster specific growth rate compared to the control group. Also, the average length of E. coli K-12 cells increased more than 27.26%. The maximum biomass and maximum specific growth rate of the stimulation group by 8000 Hz, 80dB sound wave was about 1.7 times and 2.5 times that of the control group, respectively. Moreover, it was observed that E. coli K-12 can respond rapidly to sound stress at both the transcriptional and posttranscriptional levels by promoting the synthesis of intracellular RNA and total protein. Some potential mechanisms may be involved in the responses of bacterial cells to sound stress.

Polyvinylpyrrolidone-induced anisotropic growth of gold nanoprisms in plasmon-driven synthesis

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

Zhai, Yueming; DuChene, Joseph S.; Wang, Yi-Chung

After more than a decade, it is still unknown whether the plasmon-mediated growth of silver nanostructures can be extended to the synthesis of other noble metals, as the molecular mechanisms governing the growth process remain elusive. Herein, we demonstrate the plasmon-driven synthesis of gold nanoprisms and elucidate the details of the photochemical growth mechanism at the single-nanoparticle level. Our investigation reveals that the surfactant polyvinylpyrrolidone preferentially adsorbs along the nanoprism perimeter and serves as a photochemical relay to direct the anisotropic growth of gold nanoprisms. This discovery confers a unique function to polyvinylpyrrolidone that is fundamentally diferent from its widelymore » accepted role as a crystal-face-blocking ligand. Additionally, we find that nanocrystal twinning exerts a profound influence on the kinetics of this photochemical process by controlling the transport of plasmon-generated hot electrons to polyvinylpyrrolidone. These insights establish a molecular-level description of the underlying mechanisms regulating the plasmon-driven synthesis of gold nanoprisms.« less

Polyvinylpyrrolidone-induced anisotropic growth of gold nanoprisms in plasmon-driven synthesis

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

Zhai, Yueming; DuChene, Joseph S.; Wang, Yi-Chung

After more than a decade, it is still unknown whether the plasmon-mediated growth of silver nanostructures can be extended to the synthesis of other noble metals, as the molecular mechanisms governing the growth process remain elusive. In this paper, we demonstrate the plasmon-driven synthesis of gold nanoprisms and elucidate the details of the photochemical growth mechanism at the single-nanoparticle level. Our investigation reveals that the surfactant polyvinylpyrrolidone preferentially adsorbs along the nanoprism perimeter and serves as a photochemical relay to direct the anisotropic growth of gold nanoprisms. This discovery confers a unique function to polyvinylpyrrolidone that is fundamentally different frommore » its widely accepted role as a crystal-face-blocking ligand. Additionally, we find that nanocrystal twinning exerts a profound influence on the kinetics of this photochemical process by controlling the transport of plasmon-generated hot electrons to polyvinylpyrrolidone. Finally, these insights establish a molecular-level description of the underlying mechanisms regulating the plasmon-driven synthesis of gold nanoprisms.« less

Polyvinylpyrrolidone-induced anisotropic growth of gold nanoprisms in plasmon-driven synthesis

DOE PAGES

Zhai, Yueming; DuChene, Joseph S.; Wang, Yi-Chung; ...

2016-07-04

After more than a decade, it is still unknown whether the plasmon-mediated growth of silver nanostructures can be extended to the synthesis of other noble metals, as the molecular mechanisms governing the growth process remain elusive. In this paper, we demonstrate the plasmon-driven synthesis of gold nanoprisms and elucidate the details of the photochemical growth mechanism at the single-nanoparticle level. Our investigation reveals that the surfactant polyvinylpyrrolidone preferentially adsorbs along the nanoprism perimeter and serves as a photochemical relay to direct the anisotropic growth of gold nanoprisms. This discovery confers a unique function to polyvinylpyrrolidone that is fundamentally different frommore » its widely accepted role as a crystal-face-blocking ligand. Additionally, we find that nanocrystal twinning exerts a profound influence on the kinetics of this photochemical process by controlling the transport of plasmon-generated hot electrons to polyvinylpyrrolidone. Finally, these insights establish a molecular-level description of the underlying mechanisms regulating the plasmon-driven synthesis of gold nanoprisms.« less

Increased cellular levels of spermidine or spermine are required for optimal DNA synthesis in lymphocytes activated by concanavalin A.

PubMed Central

Fillingame, R H; Jorstad, C M; Morris, D R

1975-01-01

There are large increases in cellular levels of the polyamines spermidine and spermine in lymphocytes induced to transform by concanavalin A. The anti-leukemic agent methylglyoxal bis(guanylhydrazone) (MGBG) blocks synthesis of these polyamines by inhibiting S-adenosylmethionine decarboxylase. Previous results showed that when cells are activated in the presence of MGBG the synthesis and processing of RNA, as well as protein synthesis, proceed as in the absence of the drug. In contrast, the incorporation of [methyl-3H]thymidine into DNA and the rate of entry of the cells into mitosis are inhibited by 60% in the presence of MGBG. Several experiments suggest that MGBG inhibits cell proliferation by directly blocking polyamine synthesis and not by an unrelated pharmacological effect: (1) the inhibitory action of MGBG is reversed by exogenously added spermidine or spermine; (2) inhibition of DNA synthesis by MGBG shows the same dose-response curve as does inhibition of spermidine and spermine synthesis; and (3) if MGBG is added to cells which have been allowed to accumulate their maximum complement of polyamines, there is no inhibition of thymidine incorporation. MGBG-treated and control cultures initiate DNA synthesis at the same time and show the same percentage of labeled cells by autoradiography. Therefore, it appears that in the absence of increased cellular levels of polyamines, lymphocytes progress normally from G0 through G1 and into S-phase. Furthermore, these experiments suggest that the increased levels of spermidine and spermine generally seen in rapidly proliferating eukaryotic systems are necessary for enhanced rates of DNA replication. PMID:1060087

Altered cellular kinetics in growth plate according to alterations in weight bearing.

PubMed

Park, Hoon; Kong, Sun Young; Kim, Hyun Woo; Yang, Ick Hwan

2012-05-01

To examine the effects of change in weight bearing on the growth plate metabolism, a simulated animal model of weightlessness was introduced and the chondrocytes' cellular kinetics was evaluated. Unloading condition on the hind-limb of Sprague-Dawley rats was created by fixing a tail and lifting the hind-limb. Six rats aged 6 weeks old were assigned to each group of unloading, reloading, and control groups of unloading or reloading. Unloading was maintained for three weeks, and then reloading was applied for another one week thereafter. Histomorphometry for the assessment of vertical length of the growth plate, 5-bromo-2'-deoxyuridin immunohistochemistry for cellular kinetics, and biotin nick end labeling transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) assay for chondrocytes apoptosis in the growth plate were performed. The vertical length of the growth plate and the proliferative potential of chondrocytes were decreased in the unloading group compared to those of control groups. Inter-group differences were more significant in the proliferative and hypertrophic zones. Reloading increased the length of growth plate and proliferative potential of chondrocytes. However, apoptotic changes in the growth plate were not affected by the alterations of weight bearing. Alterations in the weight bearing induced changes in the chondrocytic proliferative potential of the growth plate, however, had no effects on the apoptosis. This may explain why non-weight bearing in various clinical situations hampers normal longitudinal bone growth. Further studies on the factors for reversibility of chondrocytic proliferation upon variable mechanical stresses are needed.

The laforin-malin complex negatively regulates glycogen synthesis by modulating cellular glucose uptake via glucose transporters.

PubMed

Singh, Pankaj Kumar; Singh, Sweta; Ganesh, Subramaniam

2012-02-01

Lafora disease (LD), an inherited and fatal neurodegenerative disorder, is characterized by increased cellular glycogen content and the formation of abnormally branched glycogen inclusions, called Lafora bodies, in the affected tissues, including neurons. Therefore, laforin phosphatase and malin ubiquitin E3 ligase, the two proteins that are defective in LD, are thought to regulate glycogen synthesis through an unknown mechanism, the defects in which are likely to underlie some of the symptoms of LD. We show here that laforin's subcellular localization is dependent on the cellular glycogen content and that the stability of laforin is determined by the cellular ATP level, the activity of 5'-AMP-activated protein kinase, and the affinity of malin toward laforin. By using cell and animal models, we further show that the laforin-malin complex regulates cellular glucose uptake by modulating the subcellular localization of glucose transporters; loss of malin or laforin resulted in an increased abundance of glucose transporters in the plasma membrane and therefore excessive glucose uptake. Loss of laforin or malin, however, did not affect glycogen catabolism. Thus, the excessive cellular glucose level appears to be the primary trigger for the abnormally higher levels of cellular glycogen seen in LD.

Expression of a transmembrane phosphotyrosine phosphatase inhibits cellular response to platelet-derived growth factor and insulin-like growth factor-1.

PubMed

Mooney, R A; Freund, G G; Way, B A; Bordwell, K L

1992-11-25

Tyrosine phosphorylation is a mechanism of signal transduction shared by many growth factor receptors and oncogene products. Phosphotyrosine phosphatases (PTPases) potentially modulate or counter-regulate these signaling pathways. To test this hypothesis, the transmembrane PTPase CD45 (leukocyte common antigen) was expressed in the murine cell line C127. Hormone-dependent autophosphorylation of the platelet-derived growth factor (PDGF) and insulin-like growth factor-1 (IGF-1) receptors was markedly reduced in cells expressing the transmembrane PTPase. Tyrosine phosphorylation of other PDGF-dependent phosphoproteins (160, 140, and 55 kDa) and IGF-1-dependent phosphoproteins (145 kDa) was similarly decreased. Interestingly, the pattern of growth factor-independent tyrosine phosphorylations was comparable in cells expressing the PTPase and control cells. This suggests a selectivity or accessibility of the PTPase limited to a subset of cellular phosphotyrosyl proteins. The maximum mitogenic response to PDGF and IGF-1 in cells expressing the PTPase was decreased by 67 and 71%, respectively. These results demonstrate that a transmembrane PTPase can both affect the tyrosine phosphorylation state of growth factor receptors and modulate proximal and distal cellular responses to the growth factors.

Evaluation of the In Vitro Effect of Gold Nanorod Aspect Ratio, Surface Charge and Chemistry on Cellular Association and Cytotoxicity

DTIC Science & Technology

2016-03-28

Synthesis of GNRs ..............................................................................................................3 3.2 PEG...chemistry we can enhance their biocompatibility while maintaining their cellular uptake. 3 3.0 METHODS 3.1 Synthesis of GNRs MTAB GNRs (MTAB-1...chlorauric acid (0.1 M) was combined at room temperature with a growth solution of CTAB (0.1 M), chlorauric acid (0.1 M) silver nitrate (0.1 M) ascorbic

Antibiotic efficacy is linked to bacterial cellular respiration

PubMed Central

Lobritz, Michael A.; Belenky, Peter; Porter, Caroline B. M.; Gutierrez, Arnaud; Yang, Jason H.; Schwarz, Eric G.; Dwyer, Daniel J.; Khalil, Ahmad S.; Collins, James J.

2015-01-01

Bacteriostatic and bactericidal antibiotic treatments result in two fundamentally different phenotypic outcomes—the inhibition of bacterial growth or, alternatively, cell death. Most antibiotics inhibit processes that are major consumers of cellular energy output, suggesting that antibiotic treatment may have important downstream consequences on bacterial metabolism. We hypothesized that the specific metabolic effects of bacteriostatic and bactericidal antibiotics contribute to their overall efficacy. We leveraged the opposing phenotypes of bacteriostatic and bactericidal drugs in combination to investigate their activity. Growth inhibition from bacteriostatic antibiotics was associated with suppressed cellular respiration whereas cell death from most bactericidal antibiotics was associated with accelerated respiration. In combination, suppression of cellular respiration by the bacteriostatic antibiotic was the dominant effect, blocking bactericidal killing. Global metabolic profiling of bacteriostatic antibiotic treatment revealed that accumulation of metabolites involved in specific drug target activity was linked to the buildup of energy metabolites that feed the electron transport chain. Inhibition of cellular respiration by knockout of the cytochrome oxidases was sufficient to attenuate bactericidal lethality whereas acceleration of basal respiration by genetically uncoupling ATP synthesis from electron transport resulted in potentiation of the killing effect of bactericidal antibiotics. This work identifies a link between antibiotic-induced cellular respiration and bactericidal lethality and demonstrates that bactericidal activity can be arrested by attenuated respiration and potentiated by accelerated respiration. Our data collectively show that antibiotics perturb the metabolic state of bacteria and that the metabolic state of bacteria impacts antibiotic efficacy. PMID:26100898

Multiple regulatory systems coordinate DNA replication with cell growth in Bacillus subtilis.

PubMed

Murray, Heath; Koh, Alan

2014-10-01

In many bacteria the rate of DNA replication is linked with cellular physiology to ensure that genome duplication is coordinated with growth. Nutrient-mediated growth rate control of DNA replication initiation has been appreciated for decades, however the mechanism(s) that connects these cell cycle activities has eluded understanding. In order to help address this fundamental question we have investigated regulation of DNA replication in the model organism Bacillus subtilis. Contrary to the prevailing view we find that changes in DnaA protein level are not sufficient to account for nutrient-mediated growth rate control of DNA replication initiation, although this regulation does require both DnaA and the endogenous replication origin. We go on to report connections between DNA replication and several essential cellular activities required for rapid bacterial growth, including respiration, central carbon metabolism, fatty acid synthesis, phospholipid synthesis, and protein synthesis. Unexpectedly, the results indicate that multiple regulatory systems are involved in coordinating DNA replication with cell physiology, with some of the regulatory systems targeting oriC while others act in a oriC-independent manner. We propose that distinct regulatory systems are utilized to control DNA replication in response to diverse physiological and chemical changes.

Time Dependence of Tip Morphology during Cellular/Dendritic Arrayed Growth

NASA Technical Reports Server (NTRS)

Song, H.; Tewari, S. N.

1996-01-01

Succinonitrile-1.9 wt pct acetone has been directionally solidified in 0.7 X 0.7-cm-square cross section pyrex ampoules in order to observe the cell/dendrite tip morphologies, not influenced by the 'wall effects', which are present during growth in the generally used thin (about 200 gm) crucibles. The tips do not maintain a steady-state shape, as is generally assumed. Instead, they fluctuate within a shape envelope. The extent of fluctuation increases with decreasing growth speed, as the micro structure changes from the dendritic to cellular. The influence of natural convection has been examined by comparing these morphologies with those grown, without convection, in the thin ampoules.

Modeling of urban growth using cellular automata (CA) optimized by Particle Swarm Optimization (PSO)

NASA Astrophysics Data System (ADS)

Khalilnia, M. H.; Ghaemirad, T.; Abbaspour, R. A.

2013-09-01

In this paper, two satellite images of Tehran, the capital city of Iran, which were taken by TM and ETM+ for years 1988 and 2010 are used as the base information layers to study the changes in urban patterns of this metropolis. The patterns of urban growth for the city of Tehran are extracted in a period of twelve years using cellular automata setting the logistic regression functions as transition functions. Furthermore, the weighting coefficients of parameters affecting the urban growth, i.e. distance from urban centers, distance from rural centers, distance from agricultural centers, and neighborhood effects were selected using PSO. In order to evaluate the results of the prediction, the percent correct match index is calculated. According to the results, by combining optimization techniques with cellular automata model, the urban growth patterns can be predicted with accuracy up to 75 %.

Cellular modelling of secondary radial growth in conifer trees: application to Pinus radiata (D. Don).

PubMed

Forest, Loïc; Demongeot, Jacques; Demongeota, Jacques

2006-05-01

The radial growth of conifer trees proceeds from the dynamics of a merismatic tissue called vascular cambium or cambium. Cambium is a thin layer of active proliferating cells. The purpose of this paper was to model the main characteristics of cambial activity and its consecutive radial growth. Cell growth is under the control of the auxin hormone indole-3-acetic. The model is composed of a discrete part, which accounts for cellular proliferation, and a continuous part involving the transport of auxin. Cambium is modeled in a two-dimensional cross-section by a cellular automaton that describes the set of all its constitutive cells. Proliferation is defined as growth and division of cambial cells under neighbouring constraints, which can eliminate some cells from the cambium. The cell-growth rate is determined from auxin concentration, calculated with the continuous model. We studied the integration of each elementary cambial cell activity into the global coherent movement of macroscopic morphogenesis. Cases of normal and abnormal growth of Pinus radiata (D. Don) are modelled. Abnormal growth includes deformed trees where gravity influences auxin transport, producing heterogeneous radial growth. Cross-sectional microscopic views are also provided to validate the model's hypothesis and results.

WNK1 Promotes PIP2 Synthesis to Coordinate Growth Factor and GPCR-Gq Signaling

PubMed Central

An, Sung-Wan; Cha, Seung-Kuy; Yoon, Joonho; Chang, Seungwoo; Ross, Elliott M.; Huang, Chou-Long

2011-01-01

Summary Background PLC-β signaling is generally thought to be mediated by allosteric activation by G proteins and Ca2+. While availability of the PIP2 substrate is limiting in some cases, its production has not been shown to be independently regulated as a signaling mechanism. WNK1 protein kinase is known to regulate ion homeostasis and cause hypertension when expression is increased by gene mutations. However, its signaling functions remain largely elusive. Results Using diacylglycerol-stimulated TRPC6 and inositol trisphosphate-mediated Ca2+ transients as cellular biosensors, we show that WNK1 stimulates PLC-β signaling in cells by promoting the synthesis of PIP2 via stimulation of phosphatidylinositol 4-kinase IIIα. WNK1 kinase activity is not required. Stimulation of PLC-β by WNK1 and by Gαq are synergistic; WNK1 activity is essential for regulation of PLC-β signaling by Gq-coupled receptors and basal input from Gq is necessary for WNK1 signaling via PLC-β. WNK1 further amplifies PLC-β signaling when it is phosphorylated by Akt kinase in response to insulin-like growth factor. Conclusions WNK1 is a novel regulator of PLC-β that acts by controlling substrate availability. WNK1 thereby coordinates signaling between G protein and Akt kinase pathways. Because PIP2 is itself a signaling molecule, regulation of PIP2 synthesis by WNK1 also allows the cell to initiate PLC signaling while independently controlling the effects of PIP2 on other targets. These findings describe a new signaling pathway for Akt-activating growth factors, a mechanism for G protein-growth factor crosstalk and a means to independently control PLC signaling and PIP2 availability. PMID:22119528

N-acetylcysteine stimulates protein synthesis in enterocytes independently of glutathione synthesis.

PubMed

Yi, Dan; Hou, Yongqing; Wang, Lei; Long, Minhui; Hu, Shengdi; Mei, Huimin; Yan, Liqiong; Hu, Chien-An Andy; Wu, Guoyao

2016-02-01

Dietary supplementation with N-acetylcysteine (NAC) has been reported to improve intestinal health and treat gastrointestinal diseases. However, the underlying mechanisms are not fully understood. According to previous reports, NAC was thought to exert its effect through glutathione synthesis. This study tested the hypothesis that NAC enhances enterocyte growth and protein synthesis independently of cellular glutathione synthesis. Intestinal porcine epithelial cells were cultured for 3 days in Dulbecco's modified Eagle medium containing 0 or 100 μM NAC. To determine a possible role for GSH (the reduced form of glutathione) in mediating the effect of NAC on cell growth and protein synthesis, additional experiments were conducted using culture medium containing 100 μM GSH, 100 μM GSH ethyl ester (GSHee), diethylmaleate (a GSH-depletion agent; 10 μM), or a GSH-synthesis inhibitor (buthionine sulfoximine, BSO; 20 μM). NAC increased cell proliferation, GSH concentration, and protein synthesis, while inhibiting proteolysis. GSHee enhanced cell proliferation and GSH concentration without affecting protein synthesis but inhibited proteolysis. Conversely, BSO or diethylmaleate reduced cell proliferation and GSH concentration without affecting protein synthesis, while promoting protein degradation. At the signaling level, NAC augmented the protein abundance of total mTOR, phosphorylated mTOR, and phosphorylated 70S6 kinase as well as mRNA levels for mTOR and p70S6 kinase in IPEC-1 cells. Collectively, these results indicate that NAC upregulates expression of mTOR signaling proteins to stimulate protein synthesis in enterocytes independently of GSH generation. Our findings provide a hitherto unrecognized biochemical mechanism for beneficial effects of NAC in intestinal cells.

Growth cone travel in space and time: the cellular ensemble of cytoskeleton, adhesion, and membrane.

PubMed

Vitriol, Eric A; Zheng, James Q

2012-03-22

Growth cones, found at the tip of axonal projections, are the sensory and motile organelles of developing neurons that enable axon pathfinding and target recognition for precise wiring of the neural circuitry. To date, many families of conserved guidance molecules and their corresponding receptors have been identified that work in space and time to ensure billions of axons to reach their targets. Research in the past two decades has also gained significant insight into the ways in which growth cones translate extracellular signals into directional migration. This review aims to examine new progress toward understanding the cellular mechanisms underlying directional motility of the growth cone and to discuss questions that remain to be addressed. Specifically, we will focus on the cellular ensemble of cytoskeleton, adhesion, and membrane and examine how the intricate interplay between these processes orchestrates the directed movement of growth cones. Copyright © 2012 Elsevier Inc. All rights reserved.

Synthesis of Core-shell Lanthanide-doped Upconversion Nanocrystals for Cellular Applications.

PubMed

Ai, Xiangzhao; Lyu, Linna; Mu, Jing; Hu, Ming; Wang, Zhimin; Xing, Bengang

2017-11-10

Lanthanide-doped upconversion nanocrystals (UCNs) have attracted much attention in recent years based on their promising and controllable optical properties, which allow for the absorption of near-infrared (NIR) light and can subsequently convert it into multiplexed emissions that span over a broad range of regions from the UV to the visible to the NIR. This article presents detailed experimental procedures for high-temperature co-precipitation synthesis of core-shell UCNs that incorporate different lanthanide ions into nanocrystals for efficiently converting deep-tissue penetrable NIR excitation (808 nm) into a strong blue emission at 480 nm. By controlling the surface modification with biocompatible polymer (polyacrylic acid, PAA), the as-prepared UCNs acquires great solubility in buffer solutions. The hydrophilic nanocrystals are further functionalized with specific ligands (dibenzyl cyclooctyne, DBCO) for localization on the cell membrane. Upon NIR light (808 nm) irradiation, the upconverted blue emission can effectively activate the light-gated channel protein on the cell membrane and specifically regulate the cation (e.g., Ca 2+ ) influx in the cytoplasm. This protocol provides a feasible methodology for the synthesis of core-shell lanthanide-doped UCNs and subsequent biocompatible surface modification for further cellular applications.

Effects of nicotine on cellular proliferation, macromolecular synthesis and cell cycle phase distribution in human and murine cells

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

Konno, S.; Chiao, J.; Rossi, J.

1986-05-01

Addition of nicotine causes a dose- and time-dependent inhibition of cell growth in established human and murine cells. In the human promyelocytic HL-60 leukemic cells, 3 mM nicotine results in a 50% inhibition of cellular proliferation after 80 h. Nicotine was also found to affect the cell cycle distribution of HL-60 cells. Treatment with 4 mM nicotine for 20 h causes an increase in proportion of Gl-phase cells (from 49% to 57%) and a significant decrease in the proportion of S-phase cells (from 41% to 32%). These results suggest that nicotine causes cell arrest in the Gl-phase which may inmore » part account for its effects on cell growth. To determine whether nicotine has a primary effect on the uptake/transport of macromolecular precursors into cells, HL-60 cells were treated with 2-6 mM nicotine for 30 h/sub 3/ at the end of which time cells were labeled with (/sup 3/H)thymidine, (/sup 3/H)uridine, (/sup 14/C)lysine and (/sup 35/S)methionine, the trichloroacetic acid (TCA) soluble and insoluble radioactivities from each of the labeling conditions were determined. These studies show that nicotine primarily affect the synthesis of proteins.« less

Platelet Activating Factor: A Growth Factor for Breast Cancer

DTIC Science & Technology

2006-09-01

synthase (ADS) increases ether lipid content, growth and PAF synthesis in MCF-7 cells. 4. Eicosapentaenoic acid (EPA) inhibits the synthesis of PAF...Schmitt, J. D., Bullock, B. C. Wykle, R. L. Reacylation of platelet activating factor with eicosapentaenoic acid in fish-oil-enriched monkey...breast cancer. Recent studies have shown that the ratio of two families of essential fatty acids is important in regulating many cellular processes

Chitin synthesis in Saccharomyces cerevisiae in response to supplementation of growth medium with glucosamine and cell wall stress.

PubMed

Bulik, Dorota A; Olczak, Mariusz; Lucero, Hector A; Osmond, Barbara C; Robbins, Phillips W; Specht, Charles A

2003-10-01

In Saccharomyces cerevisiae most chitin is synthesized by Chs3p, which deposits chitin in the lateral cell wall and in the bud-neck region during cell division. We have recently found that addition of glucosamine (GlcN) to the growth medium leads to a three- to fourfold increase in cell wall chitin levels. We compared this result to the increases in cellular chitin levels associated with cell wall stress and with treatment of yeast with mating pheromone. Since all three phenomena lead to increases in precursors of chitin, we hypothesized that chitin synthesis is at least in part directly regulated by the size of this pool. This hypothesis was strengthened by our finding that addition of GlcN to the growth medium causes a rapid increase in chitin synthesis without any pronounced change in the expression of more than 6,000 genes monitored with Affymetrix gene expression chips. In other studies we found that the specific activity of Chs3p is higher in the total membrane fractions from cells grown in GlcN and from mutants with weakened cell walls. Sucrose gradient analysis shows that Chs3p is present in an inactive form in what may be Golgi compartments but as an active enzyme in other intracellular membrane-bound vesicles, as well as in the plasma membrane. We conclude that Chs3p-dependent chitin synthesis in S. cerevisiae is regulated both by the levels of intermediates of the UDP-GlcNAc biosynthetic pathway and by an increase in the activity of the enzyme in the plasma membrane.

Chitin Synthesis in Saccharomyces cerevisiae in Response to Supplementation of Growth Medium with Glucosamine and Cell Wall Stress

PubMed Central

Bulik, Dorota A.; Olczak, Mariusz; Lucero, Hector A.; Osmond, Barbara C.; Robbins, Phillips W.; Specht, Charles A.

2003-01-01

In Saccharomyces cerevisiae most chitin is synthesized by Chs3p, which deposits chitin in the lateral cell wall and in the bud-neck region during cell division. We have recently found that addition of glucosamine (GlcN) to the growth medium leads to a three- to fourfold increase in cell wall chitin levels. We compared this result to the increases in cellular chitin levels associated with cell wall stress and with treatment of yeast with mating pheromone. Since all three phenomena lead to increases in precursors of chitin, we hypothesized that chitin synthesis is at least in part directly regulated by the size of this pool. This hypothesis was strengthened by our finding that addition of GlcN to the growth medium causes a rapid increase in chitin synthesis without any pronounced change in the expression of more than 6,000 genes monitored with Affymetrix gene expression chips. In other studies we found that the specific activity of Chs3p is higher in the total membrane fractions from cells grown in GlcN and from mutants with weakened cell walls. Sucrose gradient analysis shows that Chs3p is present in an inactive form in what may be Golgi compartments but as an active enzyme in other intracellular membrane-bound vesicles, as well as in the plasma membrane. We conclude that Chs3p-dependent chitin synthesis in S. cerevisiae is regulated both by the levels of intermediates of the UDP-GlcNAc biosynthetic pathway and by an increase in the activity of the enzyme in the plasma membrane. PMID:14555471

The cellular growth rate controls overall mRNA turnover, and modulates either transcription or degradation rates of particular gene regulons.

PubMed

García-Martínez, José; Delgado-Ramos, Lidia; Ayala, Guillermo; Pelechano, Vicent; Medina, Daniel A; Carrasco, Fany; González, Ramón; Andrés-León, Eduardo; Steinmetz, Lars; Warringer, Jonas; Chávez, Sebastián; Pérez-Ortín, José E

2016-05-05

We analyzed 80 different genomic experiments, and found a positive correlation between both RNA polymerase II transcription and mRNA degradation with growth rates in yeast. Thus, in spite of the marked variation in mRNA turnover, the total mRNA concentration remained approximately constant. Some genes, however, regulated their mRNA concentration by uncoupling mRNA stability from the transcription rate. Ribosome-related genes modulated their transcription rates to increase mRNA levels under fast growth. In contrast, mitochondria-related and stress-induced genes lowered mRNA levels by reducing mRNA stability or the transcription rate, respectively. We also detected these regulations within the heterogeneity of a wild-type cell population growing in optimal conditions. The transcriptomic analysis of sorted microcolonies confirmed that the growth rate dictates alternative expression programs by modulating transcription and mRNA decay.The regulation of overall mRNA turnover keeps a constant ratio between mRNA decay and the dilution of [mRNA] caused by cellular growth. This regulation minimizes the indiscriminate transmission of mRNAs from mother to daughter cells, and favors the response capacity of the latter to physiological signals and environmental changes. We also conclude that, by uncoupling mRNA synthesis from decay, cells control the mRNA abundance of those gene regulons that characterize fast and slow growth. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

Shape selection criterion for cellular array during constrained growth of binary alloys - Need for low gravity experiment

NASA Technical Reports Server (NTRS)

Tewari, Surendra N.; Trivedi, Rohit

1991-01-01

Development of steady-state periodic cellular array is one of the critical problems in the study of nonlinear pattern formation during directional solidification of binary alloys. The criterion which establishes the values of cell tip radius and spacing under given growth condition is not known. Theoretical models, such as marginal stability and microscopic solvability, have been developed for purely diffusive regime. However, the experimental conditions where cellular structures are stable are precisely the ones where the convection effects are predominant. Thus, the critical data for meaningful evaluation of cellular array growth models can only be obtained by partial directional solidification and quenching experiments carried out in the low gravity environment of space.

Macro-cellular silica foams: synthesis during the natural creaming process of an oil-in-water emulsion.

PubMed

Sen, T; Tiddy, G J T; Casci, J L; Anderson, M W

2003-09-07

The room-temperature synthesis of a macro-mesoporous silica material during the natural creaming process of an oil-in-water emulsion is reported. The material has 3-dimensional interconnected macropores with a strut-like structure similar to meso-cellular silica foams with mesoporous walls of worm-hole structure. The material has very high surface area (approximately 800 m2 g(-1)) with narrow mesopore size distribution.

Multiple Regulatory Systems Coordinate DNA Replication with Cell Growth in Bacillus subtilis

PubMed Central

Murray, Heath; Koh, Alan

2014-01-01

In many bacteria the rate of DNA replication is linked with cellular physiology to ensure that genome duplication is coordinated with growth. Nutrient-mediated growth rate control of DNA replication initiation has been appreciated for decades, however the mechanism(s) that connects these cell cycle activities has eluded understanding. In order to help address this fundamental question we have investigated regulation of DNA replication in the model organism Bacillus subtilis. Contrary to the prevailing view we find that changes in DnaA protein level are not sufficient to account for nutrient-mediated growth rate control of DNA replication initiation, although this regulation does require both DnaA and the endogenous replication origin. We go on to report connections between DNA replication and several essential cellular activities required for rapid bacterial growth, including respiration, central carbon metabolism, fatty acid synthesis, phospholipid synthesis, and protein synthesis. Unexpectedly, the results indicate that multiple regulatory systems are involved in coordinating DNA replication with cell physiology, with some of the regulatory systems targeting oriC while others act in a oriC-independent manner. We propose that distinct regulatory systems are utilized to control DNA replication in response to diverse physiological and chemical changes. PMID:25340815

Peptidoglycan Synthesis Machinery in Agrobacterium tumefaciens During Unipolar Growth and Cell Division

PubMed Central

Cameron, Todd A.; Anderson-Furgeson, James; Zupan, John R.; Zik, Justin J.

2014-01-01

ABSTRACT The synthesis of peptidoglycan (PG) in bacteria is a crucial process controlling cell shape and vitality. In contrast to bacteria such as Escherichia coli that grow by dispersed lateral insertion of PG, little is known of the processes that direct polar PG synthesis in other bacteria such as the Rhizobiales. To better understand polar growth in the Rhizobiales Agrobacterium tumefaciens, we first surveyed its genome to identify homologs of (~70) well-known PG synthesis components. Since most of the canonical cell elongation components are absent from A. tumefaciens, we made fluorescent protein fusions to other putative PG synthesis components to assay their subcellular localization patterns. The cell division scaffolds FtsZ and FtsA, PBP1a, and a Rhizobiales- and Rhodobacterales-specific l,d-transpeptidase (LDT) all associate with the elongating cell pole. All four proteins also localize to the septum during cell division. Examination of the dimensions of growing cells revealed that new cell compartments gradually increase in width as they grow in length. This increase in cell width is coincident with an expanded region of LDT-mediated PG synthesis activity, as measured directly through incorporation of exogenous d-amino acids. Thus, unipolar growth in the Rhizobiales is surprisingly dynamic and represents a significant departure from the canonical growth mechanism of E. coli and other well-studied bacilli. PMID:24865559

One-step Melt Synthesis of Water Soluble, Photoluminescent, Surface-Oxidized Silicon Nanoparticles for Cellular Imaging Applications

PubMed Central

Manhat, Beth A.; Brown, Anna L.; Black, Labe A.; Ross, J.B. Alexander; Fichter, Katye; Vu, Tania; Richman, Erik

2012-01-01

We have developed a versatile, one-step melt synthesis of water-soluble, highly emissive silicon nanoparticles using bi-functional, low-melting solids (such as glutaric acid) as reaction media. Characterization through transmission electron microscopy, selected area electron diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy shows that the one-step melt synthesis produces nanoscale Si cores surrounded by a silicon oxide shell. Analysis of the nanoparticle surface using FT-IR, zeta potential, and gel electrophoresis indicates that the bi-functional ligand used in the one-step synthesis is grafted onto the nanoparticle, which allows for tuning of the particle surface charge, solubility, and functionality. Photoluminescence spectra of the as-prepared glutaric acid-synthesized silicon nanoparticles show an intense blue-green emission with a short (ns) lifetime suitable for biological imaging. These nanoparticles are found to be stable in biological media and have been used to examine cellular uptake and distribution in live N2a cells. PMID:23139440

Insulin-like growth factor-I, physical activity, and control of cellular anabolism.

PubMed

Nindl, Bradley C

2010-01-01

The underlying mechanisms responsible for mediating the beneficial outcomes of exercise undoubtedly are many, but the insulin-like growth factor-I (IGF-I) system is emerging as an important and central hormonal axis that plays a significant role concerning cellular anabolism. This introductory article summarizes the intent and the content for papers presented as part of a 2008 American College of Sports Medicine national symposium entitled "Insulin-like Growth Factor-I, Physical Activity, and Control of Cellular Anabolism." The individual authors and their papers are as follows: Jan Frystyk authoring "The relationship between exercise and the growth hormone/insulin-like growth factor-I axis," Greg Adams authoring "IGF-I signaling in skeletal muscle and the potential for cytokine interactions," and Brad Nindl authoring "Insulin-like growth factor-I as a biomarker of health, fitness, and training status." These papers focus on 1) different assay methodologies for IGF-I within the paradigm of exercise studies, 2) research demonstrating that intracellular signaling components associated with several proinflammatory cytokines have the potential to interact with anabolic signaling processes in skeletal muscle, and 3) an overview of IGF-I as a biomarker related to exercise training, muscle and bone remodeling, body composition, cognition, and cancer. When summed in total, the contribution that these papers will make will undoubtedly involve bringing attention to the vast regulatory complexity of the IGF-I system and will hopefully convince the reader that the IGF-I system warrants further detailed scientific inquiry to resolve many unanswered questions and paradoxical experimental findings. The IGF-I system remains one of the most intriguing and captivating marvels of human physiology that seems central in mediating numerous adaptations from physical activity.

Choline pathways during normal and stimulated renal growth in rats.

PubMed Central

Bean, G H; Lowenstein, L M

1978-01-01

Cellular membrane synthesis occurs during normal and stimulated renal growth. Choline in the kidney is utilized as a precursor for membrane synthesis via the choline kinase reaction. We investigated choline phosphorylation during normal and stimulated renal growth. Rapidly growing neonatal rat kidneys contained relatively high levels of choline kinase activity (61 pmol phosphorylcholine/min per mg protein). Choline kinase activity and phosphorylcholine production then fell gradually over the 1st mo of life; by 1 mo phosphorylcholine production was 34 pmol phosphorylcholine/min per mg protein. Choline kinase activity increased by 27% (P less than 0.001) in 28-day-old rats when renal growth was stimulated by contralateral nephrectomy; the increase occurred within 2 h after surgery. Thus, changes in the activity of this important enzyme in the initiation of membrane synthesis is associated both with normal renal development and with adaptation to nephron loss. The findings further suggest that the cell membrane may be involved in the initiation of compensatory renal growth. PMID:659614

Vitamin B12–dependent taurine synthesis regulates growth and bone mass

PubMed Central

Roman-Garcia, Pablo; Quiros-Gonzalez, Isabel; Mottram, Lynda; Lieben, Liesbet; Sharan, Kunal; Wangwiwatsin, Arporn; Tubio, Jose; Lewis, Kirsty; Wilkinson, Debbie; Santhanam, Balaji; Sarper, Nazan; Clare, Simon; Vassiliou, George S.; Velagapudi, Vidya R.; Dougan, Gordon; Yadav, Vijay K.

2014-01-01

Both maternal and offspring-derived factors contribute to lifelong growth and bone mass accrual, although the specific role of maternal deficiencies in the growth and bone mass of offspring is poorly understood. In the present study, we have shown that vitamin B12 (B12) deficiency in a murine genetic model results in severe postweaning growth retardation and osteoporosis, and the severity and time of onset of this phenotype in the offspring depends on the maternal genotype. Using integrated physiological and metabolomic analysis, we determined that B12 deficiency in the offspring decreases liver taurine production and associates with abrogation of a growth hormone/insulin-like growth factor 1 (GH/IGF1) axis. Taurine increased GH-dependent IGF1 synthesis in the liver, which subsequently enhanced osteoblast function, and in B12-deficient offspring, oral administration of taurine rescued their growth retardation and osteoporosis phenotypes. These results identify B12 as an essential vitamin that positively regulates postweaning growth and bone formation through taurine synthesis and suggests potential therapies to increase bone mass. PMID:24911144

Mechanistic links between cellular trade-offs, gene expression, and growth.

PubMed

Weiße, Andrea Y; Oyarzún, Diego A; Danos, Vincent; Swain, Peter S

2015-03-03

Intracellular processes rarely work in isolation but continually interact with the rest of the cell. In microbes, for example, we now know that gene expression across the whole genome typically changes with growth rate. The mechanisms driving such global regulation, however, are not well understood. Here we consider three trade-offs that, because of limitations in levels of cellular energy, free ribosomes, and proteins, are faced by all living cells and we construct a mechanistic model that comprises these trade-offs. Our model couples gene expression with growth rate and growth rate with a growing population of cells. We show that the model recovers Monod's law for the growth of microbes and two other empirical relationships connecting growth rate to the mass fraction of ribosomes. Further, we can explain growth-related effects in dosage compensation by paralogs and predict host-circuit interactions in synthetic biology. Simulating competitions between strains, we find that the regulation of metabolic pathways may have evolved not to match expression of enzymes to levels of extracellular substrates in changing environments but rather to balance a trade-off between exploiting one type of nutrient over another. Although coarse-grained, the trade-offs that the model embodies are fundamental, and, as such, our modeling framework has potentially wide application, including in both biotechnology and medicine.

Postnatal Exocrine Pancreas Growth by Cellular Hypertrophy Correlates with a Shorter Lifespan in Mammals.

PubMed

Anzi, Shira; Stolovich-Rain, Miri; Klochendler, Agnes; Fridlich, Ori; Helman, Aharon; Paz-Sonnenfeld, Avital; Avni-Magen, Nili; Kaufman, Elizabeth; Ginzberg, Miriam B; Snider, Daniel; Ray, Saikat; Brecht, Michael; Holmes, Melissa M; Meir, Karen; Avivi, Aaron; Shams, Imad; Berkowitz, Asaf; Shapiro, A M James; Glaser, Benjamin; Ben-Sasson, Shmuel; Kafri, Ran; Dor, Yuval

2018-06-18

Developmental processes in different mammals are thought to share fundamental cellular mechanisms. We report a dramatic increase in cell size during postnatal pancreas development in rodents, accounting for much of the increase in organ size after birth. Hypertrophy of pancreatic acinar cells involves both higher ploidy and increased biosynthesis per genome copy; is maximal adjacent to islets, suggesting endocrine to exocrine communication; and is partly driven by weaning-related processes. In contrast to the situation in rodents, pancreas cell size in humans remains stable postnatally, indicating organ growth by pure hyperplasia. Pancreatic acinar cell volume varies 9-fold among 24 mammalian species analyzed, and shows a striking inverse correlation with organismal lifespan. We hypothesize that cellular hypertrophy is a strategy for rapid postnatal tissue growth, entailing life-long detrimental effects. Copyright © 2018 Elsevier Inc. All rights reserved.

The growth hormone–insulin-like growth factor-I axis in the diagnosis and treatment of growth disorders

PubMed Central

Blum, Werner F; Alherbish, Abdullah; Alsagheir, Afaf; El Awwa, Ahmed; Kaplan, Walid; Koledova, Ekaterina; Savage, Martin O

2018-01-01

The growth hormone (GH)–insulin-like growth factor (IGF)-I axis is a key endocrine mechanism regulating linear growth in children. While paediatricians have a good knowledge of GH secretion and assessment, understanding and use of measurements of the components of the IGF system are less current in clinical practice. The physiological function of this axis is to increase the anabolic cellular processes of protein synthesis and mitosis, and reduction of apoptosis, with each being regulated in the appropriate target tissue. Measurement of serum IGF-I and IGF-binding protein (IGFBP)-3 concentrations can complement assessment of GH status in the investigation of short stature and contribute to prediction of growth response during GH therapy. IGF-I monitoring during GH therapy also informs the clinician about adherence and provides a safety reference to avoid over-dosing during long-term management. PMID:29724795

The growth hormone-insulin-like growth factor-I axis in the diagnosis and treatment of growth disorders.

PubMed

Blum, Werner; Alherbish, Abdullah; Alsagheir, Afaf; El Awwa, Ahmed; Kaplan, Walid; Koledova, Ekaterina; Savage, Martin O

2018-05-03

The growth hormone (GH)-insulin-like growth factor (IGF)-I axis is a key endocrine mechanism regulating linear growth in children. While paediatricians have a good knowledge of GH secretion and assessment, understanding and use of measurements of the components of the IGF system are less current in clinical practice. The physiological function of this axis is to increase the anabolic cellular processes of protein synthesis and mitosis, and reduction of apoptosis, with each being regulated in the appropriate target tissue. Measurement of serum IGF-I and IGFBP-3 concentrations can complement assessment of GH status in the investigation of short stature and contribute to prediction of growth response during GH therapy. IGF-I monitoring during GH therapy also informs the clinician about adherence and provides a safety reference to avoid over-dosing during long-term management.

Synthesis of marmycin A and investigation into its cellular activity

NASA Astrophysics Data System (ADS)

Cañeque, Tatiana; Gomes, Filipe; Mai, Trang Thi; Maestri, Giovanni; Malacria, Max; Rodriguez, Raphaël

2015-09-01

Anthracyclines such as doxorubicin are used extensively in the treatment of cancers. Anthraquinone-related angucyclines also exhibit antiproliferative properties and have been proposed to operate via similar mechanisms, including direct genome targeting. Here, we report the chemical synthesis of marmycin A and the study of its cellular activity. The aromatic core was constructed by means of a one-pot multistep reaction comprising a regioselective Diels-Alder cycloaddition, and the complex sugar backbone was introduced through a copper-catalysed Ullmann cross-coupling, followed by a challenging Friedel-Crafts cyclization. Remarkably, fluorescence microscopy revealed that marmycin A does not target the nucleus but instead accumulates in lysosomes, thereby promoting cell death independently of genome targeting. Furthermore, a synthetic dimer of marmycin A and the lysosome-targeting agent artesunate exhibited a synergistic activity against the invasive MDA-MB-231 cancer cell line. These findings shed light on the elusive pathways through which anthraquinone derivatives act in cells, pointing towards unanticipated biological and therapeutic applications.

A Systems Biology Approach Uncovers Cellular Strategies Used by Methylobacterium extorquens AM1 During the Switch from Multi- to Single-Carbon Growth

PubMed Central

Skovran, Elizabeth; Crowther, Gregory J.; Guo, Xiaofeng; Yang, Song; Lidstrom, Mary E.

2010-01-01

Background When organisms experience environmental change, how does their metabolic network reset and adapt to the new condition? Methylobacterium extorquens is a bacterium capable of growth on both multi- and single-carbon compounds. These different modes of growth utilize dramatically different central metabolic pathways with limited pathway overlap. Methodology/Principal Findings This study focused on the mechanisms of metabolic adaptation occurring during the transition from succinate growth (predicted to be energy-limited) to methanol growth (predicted to be reducing-power-limited), analyzing changes in carbon flux, gene expression, metabolites and enzymatic activities over time. Initially, cells experienced metabolic imbalance with excretion of metabolites, changes in nucleotide levels and cessation of cell growth. Though assimilatory pathways were induced rapidly, a transient block in carbon flow to biomass synthesis occurred, and enzymatic assays suggested methylene tetrahydrofolate dehydrogenase as one control point. This “downstream priming” mechanism ensures that significant carbon flux through these pathways does not occur until they are fully induced, precluding the buildup of toxic intermediates. Most metabolites that are required for growth on both carbon sources did not change significantly, even though transcripts and enzymatic activities required for their production changed radically, underscoring the concept of metabolic setpoints. Conclusions/Significance This multi-level approach has resulted in new insights into the metabolic strategies carried out to effect this shift between two dramatically different modes of growth and identified a number of potential flux control and regulatory check points as a further step toward understanding metabolic adaptation and the cellular strategies employed to maintain metabolic setpoints. PMID:21124828

A systems biology approach uncovers cellular strategies used by Methylobacterium extorquens AM1 during the switch from multi- to single-carbon growth.

PubMed

Skovran, Elizabeth; Crowther, Gregory J; Guo, Xiaofeng; Yang, Song; Lidstrom, Mary E

2010-11-24

When organisms experience environmental change, how does their metabolic network reset and adapt to the new condition? Methylobacterium extorquens is a bacterium capable of growth on both multi- and single-carbon compounds. These different modes of growth utilize dramatically different central metabolic pathways with limited pathway overlap. This study focused on the mechanisms of metabolic adaptation occurring during the transition from succinate growth (predicted to be energy-limited) to methanol growth (predicted to be reducing-power-limited), analyzing changes in carbon flux, gene expression, metabolites and enzymatic activities over time. Initially, cells experienced metabolic imbalance with excretion of metabolites, changes in nucleotide levels and cessation of cell growth. Though assimilatory pathways were induced rapidly, a transient block in carbon flow to biomass synthesis occurred, and enzymatic assays suggested methylene tetrahydrofolate dehydrogenase as one control point. This "downstream priming" mechanism ensures that significant carbon flux through these pathways does not occur until they are fully induced, precluding the buildup of toxic intermediates. Most metabolites that are required for growth on both carbon sources did not change significantly, even though transcripts and enzymatic activities required for their production changed radically, underscoring the concept of metabolic setpoints. This multi-level approach has resulted in new insights into the metabolic strategies carried out to effect this shift between two dramatically different modes of growth and identified a number of potential flux control and regulatory check points as a further step toward understanding metabolic adaptation and the cellular strategies employed to maintain metabolic setpoints.

Characterization of the cell growth analysis for detection of immortal cellular impurities in human mesenchymal stem cells.

PubMed

Kono, Ken; Takada, Nozomi; Yasuda, Satoshi; Sawada, Rumi; Niimi, Shingo; Matsuyama, Akifumi; Sato, Yoji

2015-03-01

The analysis of in vitro cell senescence/growth after serial passaging can be one of ways to show the absence of immortalized cells, which are frequently tumorigenic, in human cell-processed therapeutic products (hCTPs). However, the performance of the cell growth analysis for detection of the immortalized cellular impurities has never been evaluated. In the present study, we examined the growth rates of human mesenchymal stem cells (hMSCs, passage 5 (P = 5)) contaminated with various doses of HeLa cells, and compared with that of hMSCs alone. The growth rates of the contaminated hMSCs were comparable to that of hMSCs alone at P = 5, but significantly increased at P = 6 (0.1% and 0.01% HeLa) or P = 7 (0.001% HeLa) within 30 days. These findings suggest that the cell growth analysis is a simple and sensitive method to detect immortalized cellular impurities in hCTPs derived from human somatic cells. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Unstable vicinal crystal growth from cellular automata

NASA Astrophysics Data System (ADS)

Krasteva, A.; Popova, H.; KrzyŻewski, F.; Załuska-Kotur, M.; Tonchev, V.

2016-03-01

In order to study the unstable step motion on vicinal crystal surfaces we devise vicinal Cellular Automata. Each cell from the colony has value equal to its height in the vicinal, initially the steps are regularly distributed. Another array keeps the adatoms, initially distributed randomly over the surface. The growth rule defines that each adatom at right nearest neighbor position to a (multi-) step attaches to it. The update of whole colony is performed at once and then time increases. This execution of the growth rule is followed by compensation of the consumed particles and by diffusional update(s) of the adatom population. Two principal sources of instability are employed - biased diffusion and infinite inverse Ehrlich-Schwoebel barrier (iiSE). Since these factors are not opposed by step-step repulsion the formation of multi-steps is observed but in general the step bunches preserve a finite width. We monitor the developing surface patterns and quantify the observations by scaling laws with focus on the eventual transition from diffusion-limited to kinetics-limited phenomenon. The time-scaling exponent of the bunch size N is 1/2 for the case of biased diffusion and 1/3 for the case of iiSE. Additional distinction is possible based on the time-scaling exponents of the sizes of multi-step Nmulti, these are 0.36÷0.4 (for biased diffusion) and 1/4 (iiSE).

Treatment Analysis in a Cancer Stem Cell Context Using a Tumor Growth Model Based on Cellular Automata.

PubMed

Monteagudo, Ángel; Santos, José

2015-01-01

Cancer can be viewed as an emergent behavior in terms of complex system theory and artificial life, Cellular Automata (CA) being the tool most used for studying and characterizing the emergent behavior. Different approaches with CA models were used to model cancer growth. The use of the abstract model of acquired cancer hallmarks permits the direct modeling at cellular level, where a cellular automaton defines the mitotic and apoptotic behavior of cells, and allows for an analysis of different dynamics of the cellular system depending on the presence of the different hallmarks. A CA model based on the presence of hallmarks in the cells, which includes a simulation of the behavior of Cancer Stem Cells (CSC) and their implications for the resultant growth behavior of the multicellular system, was employed. This modeling of cancer growth, in the avascular phase, was employed to analyze the effect of cancer treatments in a cancer stem cell context. The model clearly explains why, after treatment against non-stem cancer cells, the regrowth capability of CSCs generates a faster regrowth of tumor behavior, and also shows that a continuous low-intensity treatment does not favor CSC proliferation and differentiation, thereby allowing an unproblematic control of future tumor regrowth. The analysis performed indicates that, contrary to the current attempts at CSC control, trying to make CSC proliferation more difficult is an important point to consider, especially in the immediate period after a standard treatment for controlling non-stem cancer cell proliferation.

Modeling of time dependent localized flow shear stress and its impact on cellular growth within additive manufactured titanium implants.

PubMed

Zhang, Ziyu; Yuan, Lang; Lee, Peter D; Jones, Eric; Jones, Julian R

2014-11-01

Bone augmentation implants are porous to allow cellular growth, bone formation and fixation. However, the design of the pores is currently based on simple empirical rules, such as minimum pore and interconnects sizes. We present a three-dimensional (3D) transient model of cellular growth based on the Navier-Stokes equations that simulates the body fluid flow and stimulation of bone precursor cellular growth, attachment, and proliferation as a function of local flow shear stress. The model's effectiveness is demonstrated for two additive manufactured (AM) titanium scaffold architectures. The results demonstrate that there is a complex interaction of flow rate and strut architecture, resulting in partially randomized structures having a preferential impact on stimulating cell migration in 3D porous structures for higher flow rates. This novel result demonstrates the potential new insights that can be gained via the modeling tool developed, and how the model can be used to perform what-if simulations to design AM structures to specific functional requirements. © 2014 Wiley Periodicals, Inc.

Modeling of time dependent localized flow shear stress and its impact on cellular growth within additive manufactured titanium implants

PubMed Central

Zhang, Ziyu; Yuan, Lang; Lee, Peter D; Jones, Eric; Jones, Julian R

2014-01-01

Bone augmentation implants are porous to allow cellular growth, bone formation and fixation. However, the design of the pores is currently based on simple empirical rules, such as minimum pore and interconnects sizes. We present a three-dimensional (3D) transient model of cellular growth based on the Navier–Stokes equations that simulates the body fluid flow and stimulation of bone precursor cellular growth, attachment, and proliferation as a function of local flow shear stress. The model's effectiveness is demonstrated for two additive manufactured (AM) titanium scaffold architectures. The results demonstrate that there is a complex interaction of flow rate and strut architecture, resulting in partially randomized structures having a preferential impact on stimulating cell migration in 3D porous structures for higher flow rates. This novel result demonstrates the potential new insights that can be gained via the modeling tool developed, and how the model can be used to perform what-if simulations to design AM structures to specific functional requirements. PMID:24664988

The Effect of Gravity Fields on Cellular Gene Expression

NASA Technical Reports Server (NTRS)

Hughes-Fulford, Millie

1999-01-01

Early theoretical analysis predicted that microgravity effects on the isolated cell would be minuscule at the subcellular level; however, these speculations have not proven true in the real world. Astronauts experience a significant bone and muscle loss in as little as 2 weeks of spaceflight and changes are seen at the cellular level soon after exposure to microgravity. Changes in biological systems may be primarily due to the lack of gravity and the resulting loss of mechanical stress on tissues and cells. Recent ground and flight studies examining the effects of gravity or mechanical stress on cells demonstrate marked changes in gene expression when relatively small changes in mechanical forces or gravity fields were made. Several immediate early genes (IEG) like c-fos and c-myc are induced by mechanical stimulation within minutes. In contrast, several investigators report that the absence of mechanical forces during space flight result in decreased sera response element (SRE) activity and attenuation of expression of IEGs such as c-fos, c-jun and cox-2 mRNAs. Clearly, these early changes in gene expression may have long term consequences on mechanically sensitive cells. In our early studies on STS-56, we reported four major changes in the osteoblast; 1) prostaglandin synthesis in flight, 2) changes in cellular morphology, 3) altered actin cytoskeleton and 4) reduced osteoblast growth after four days exposure to microgravity. Initially, it was believed that changes in fibronectin (FN) RNA, FN protein synthesis or subsequent FN matrix formation might account for the changes in cytoskeleton and/ or reduction of growth. However our recent studies on Biorack (STS-76, STS-81 and STS-84), using ground and in-flight 1-G controls, demonstrated that fibronectin synthesis and matrix formation were normal in microgravity. In addition, in our most recent Biorack paper, our laboratory has documented that relative protein synthesis and mRNA synthesis are not changed after 24

Guanosine 3'-diphosphate 5'-diphosphate is not required for growth rate-dependent control of rRNA synthesis in Escherichia coli.

PubMed Central

Gaal, T; Gourse, R L

1990-01-01

rRNA synthesis in Escherichia coli is subject to at least two regulation systems, growth rate-dependent control and stringent control. The inverse correlation between rRNA synthesis rates and guanosine 3'-diphosphate 5'-diphosphate (ppGpp) levels under various physiological conditions has led to the supposition that ppGpp is the mediator of both control mechanisms by inhibiting transcription from rrn P1 promoters. Recently, relA- spoT- strains have been constructed in which both ppGpp synthesis pathways most likely have been removed (M. Cashel, personal communication). We have confirmed that such strains produce no detectable ppGpp and therefore offer a direct means for testing the involvement of ppGpp in the regulation of rRNA synthesis in vivo. Stringent control was determined by measurement of rRNA synthesis after amino acid starvation, while growth rate control was determined by measurement of rRNA synthesis under different nutritional conditions. As expected, the relA- spoT- strain is relaxed for stringent control. However, growth rate-dependent regulation is unimpaired. These results indicate that growth rate regulation can occur in the absence of ppGpp and imply that ppGpp is not the mediator, or at least is not the sole mediator, of growth rate-dependent control. Therefore, growth rate-dependent control and stringent control may utilize different mechanisms for regulating stable RNA synthesis. PMID:2196571

TIF-IA-dependent regulation of ribosome synthesis in drosophila muscle is required to maintain systemic insulin signaling and larval growth.

PubMed

Ghosh, Abhishek; Rideout, Elizabeth J; Grewal, Savraj S

2014-10-01

The conserved TOR kinase signaling network links nutrient availability to cell, tissue and body growth in animals. One important growth-regulatory target of TOR signaling is ribosome biogenesis. Studies in yeast and mammalian cell culture have described how TOR controls rRNA synthesis-a limiting step in ribosome biogenesis-via the RNA Polymerase I transcription factor TIF-IA. However, the contribution of TOR-dependent ribosome synthesis to tissue and body growth in animals is less clear. Here we show in Drosophila larvae that ribosome synthesis in muscle is required non-autonomously to maintain normal body growth and development. We find that amino acid starvation and TOR inhibition lead to reduced levels of TIF-IA, and decreased rRNA synthesis in larval muscle. When we mimic this decrease in muscle ribosome synthesis using RNAi-mediated knockdown of TIF-IA, we observe delayed larval development and reduced body growth. This reduction in growth is caused by lowered systemic insulin signaling via two endocrine responses: reduced expression of Drosophila insulin-like peptides (dILPs) from the brain and increased expression of Imp-L2-a secreted factor that binds and inhibits dILP activity-from muscle. We also observed that maintaining TIF-IA levels in muscle could partially reverse the starvation-mediated suppression of systemic insulin signaling. Finally, we show that activation of TOR specifically in muscle can increase overall body size and this effect requires TIF-IA function. These data suggest that muscle ribosome synthesis functions as a nutrient-dependent checkpoint for overall body growth: in nutrient rich conditions, TOR is required to maintain levels of TIF-IA and ribosome synthesis to promote high levels of systemic insulin, but under conditions of starvation stress, reduced muscle ribosome synthesis triggers an endocrine response that limits systemic insulin signaling to restrict growth and maintain homeostasis.

Thermosolutal convection during cellular arrayed growth of Pb-Sn alloys

NASA Technical Reports Server (NTRS)

Tewari, S. N.; Shah, Rajesh; Chopra, M. A.

1993-01-01

Thermosolutal convection caused by the solute build up ahead of the growing arrays of cells and dendrites results in macrosegregation along the length of the Pb-Sn alloy (10 to 58 wt pct Sn) specimens when they are directionally solidified in a positive thermal gradient (melt on top, solid below, and gravity pointing down). At a constant thermal gradient, the extent of macrosegregation increases with decreasing growth speed as the microstructure changes from dendritic, to cellular and to planar. An empirical parameter, effective partition coefficient, obtained from the dependence of the longitudinal macrosegregation on fraction distance solidified can be used to represent the extent of macrosegregation.

Amino acids and autophagy: cross-talk and co-operation to control cellular homeostasis.

PubMed

Carroll, Bernadette; Korolchuk, Viktor I; Sarkar, Sovan

2015-10-01

Maintenance of amino acid homeostasis is important for healthy cellular function, metabolism and growth. Intracellular amino acid concentrations are dynamic; the high demand for protein synthesis must be met with constant dietary intake, followed by cellular influx, utilization and recycling of nutrients. Autophagy is a catabolic process via which superfluous or damaged proteins and organelles are delivered to the lysosome and degraded to release free amino acids into the cytoplasm. Furthermore, autophagy is specifically activated in response to amino acid starvation via two key signaling cascades: the mammalian target of rapamycin (mTOR) complex 1 (mTORC1) and the general control nonderepressible 2 (GCN2) pathways. These pathways are key regulators of the integration between anabolic (amino acid depleting) and catabolic (such as autophagy which is amino acid replenishing) processes to ensure intracellular amino acid homeostasis. Here, we discuss the key roles that amino acids, along with energy (ATP, glucose) and oxygen, are playing in cellular growth and proliferation. We further explore how sophisticated methods are employed by cells to sense intracellular amino acid concentrations, how amino acids can act as a switch to dictate the temporal and spatial activation of anabolic and catabolic processes and how autophagy contributes to the replenishment of free amino acids, all to ensure cell survival. Relevance of these molecular processes to cellular and organismal physiology and pathology is also discussed.

Carbon flux to growth or polyhydroxyalkanoate synthesis under microaerophilic conditions is affected by fatty acid chain-length in Pseudomonas putida LS46.

PubMed

Blunt, Warren; Dartiailh, Christopher; Sparling, Richard; Gapes, Daniel; Levin, David B; Cicek, Nazim

2018-05-24

Economical production of medium-chain length polyhydroxyalkanoates (mcl-PHA) is dependent on efficient cultivation processes. This work describes growth and mcl-PHA synthesis characteristics of Pseudomonas putida LS46 when grown on medium-chain length fatty acids (octanoic acid) and lower-cost long-chain fatty acids (LCFAs, derived from hydrolyzed canola oil) in microaerophilic environments. Growth on octanoic acid ceased when the oxygen uptake rate was limited by the oxygen transfer rate, and mcl-PHA accumulated to 61.9% of the cell dry mass. From LCFAs, production of non-PHA cell mass continued at a rate of 0.36 g L -1  h -1 under oxygen-limited conditions, while mcl-PHA accumulated simultaneously to 31% of the cell dry mass. The titer of non-PHA cell mass from LCFAs at 14 h post-inoculation was double that obtained from octanoic acid in bioreactors operated with identical feeding and aeration conditions. While the productivity for octanoic acid was higher by 14 h, prolonged cultivation on LCFAs achieved similar productivity but with twice the PHA titer. Simultaneous co-feeding of each substrate demonstrated the continued cell growth under microaerophilic conditions characteristic of LCFAs, and the resulting polymer was dominant in C8 monomers. Furthermore, co-feeding resulted in improved PHA titer and volumetric productivity compared to either substrate individually. These results suggest that LCFAs improve growth of P. putida in oxygen-limited environments and could reduce production costs since more non-PHA cell mass, the cellular factories required to produce mcl-PHA and the most oxygen-intensive cellular process, can be produced for a given oxygen transfer rate.

TIF-IA-Dependent Regulation of Ribosome Synthesis in Drosophila Muscle Is Required to Maintain Systemic Insulin Signaling and Larval Growth

PubMed Central

Ghosh, Abhishek; Rideout, Elizabeth J.; Grewal, Savraj S.

2014-01-01

The conserved TOR kinase signaling network links nutrient availability to cell, tissue and body growth in animals. One important growth-regulatory target of TOR signaling is ribosome biogenesis. Studies in yeast and mammalian cell culture have described how TOR controls rRNA synthesis—a limiting step in ribosome biogenesis—via the RNA Polymerase I transcription factor TIF-IA. However, the contribution of TOR-dependent ribosome synthesis to tissue and body growth in animals is less clear. Here we show in Drosophila larvae that ribosome synthesis in muscle is required non-autonomously to maintain normal body growth and development. We find that amino acid starvation and TOR inhibition lead to reduced levels of TIF-IA, and decreased rRNA synthesis in larval muscle. When we mimic this decrease in muscle ribosome synthesis using RNAi-mediated knockdown of TIF-IA, we observe delayed larval development and reduced body growth. This reduction in growth is caused by lowered systemic insulin signaling via two endocrine responses: reduced expression of Drosophila insulin-like peptides (dILPs) from the brain and increased expression of Imp-L2—a secreted factor that binds and inhibits dILP activity—from muscle. We also observed that maintaining TIF-IA levels in muscle could partially reverse the starvation-mediated suppression of systemic insulin signaling. Finally, we show that activation of TOR specifically in muscle can increase overall body size and this effect requires TIF-IA function. These data suggest that muscle ribosome synthesis functions as a nutrient-dependent checkpoint for overall body growth: in nutrient rich conditions, TOR is required to maintain levels of TIF-IA and ribosome synthesis to promote high levels of systemic insulin, but under conditions of starvation stress, reduced muscle ribosome synthesis triggers an endocrine response that limits systemic insulin signaling to restrict growth and maintain homeostasis. PMID:25356674

Ribosome Synthesis and MAPK Activity Modulate Ionizing Radiation-Induced Germ Cell Apoptosis in Caenorhabditis elegans

PubMed Central

Eberhard, Ralf; Stergiou, Lilli; Hofmann, E. Randal; Hofmann, Jen; Haenni, Simon; Teo, Youjin; Furger, André; Hengartner, Michael O.

2013-01-01

Synthesis of ribosomal RNA by RNA polymerase I (RNA pol I) is an elemental biological process and is key for cellular homeostasis. In a forward genetic screen in C. elegans designed to identify DNA damage-response factors, we isolated a point mutation of RNA pol I, rpoa-2(op259), that leads to altered rRNA synthesis and a concomitant resistance to ionizing radiation (IR)-induced germ cell apoptosis. This weak apoptotic IR response could be phenocopied when interfering with other factors of ribosome synthesis. Surprisingly, despite their resistance to DNA damage, rpoa-2(op259) mutants present a normal CEP-1/p53 response to IR and increased basal CEP-1 activity under normal growth conditions. In parallel, rpoa-2(op259) leads to reduced Ras/MAPK pathway activity, which is required for germ cell progression and physiological germ cell death. Ras/MAPK gain-of-function conditions could rescue the IR response defect in rpoa-2(op259), pointing to a function for Ras/MAPK in modulating DNA damage-induced apoptosis downstream of CEP-1. Our data demonstrate that a single point mutation in an RNA pol I subunit can interfere with multiple key signalling pathways. Ribosome synthesis and growth-factor signalling are perturbed in many cancer cells; such an interplay between basic cellular processes and signalling might be critical for how tumours evolve or respond to treatment. PMID:24278030

Design, synthesis and cellular metabolism study of 4'-selenonucleosides.

PubMed

Yu, Jinha; Sahu, Pramod K; Kim, Gyudong; Qu, Shuhao; Choi, Yoojin; Song, Jayoung; Lee, Sang Kook; Noh, Minsoo; Park, Sunghyouk; Jeong, Lak Shin

2015-01-01

4'-seleno-homonucleosides were synthesized as next-generation nucleosides, and their cellular phosphorylation was studied to confirm the hypothesis that bulky selenium atom can sterically hinder the approach of cellular nucleoside kinase to the 5'-OH for phosphorylation. 4'-seleno-homonucleosides (n = 2), with one-carbon homologation, were synthesized through a tandem seleno-Michael addition-SN2 ring cyclization. LC-MS analysis demonstrated that they were phosphorylated by cellular nucleoside kinases, resulting in anticancer activity. The bulky selenium atom played a key role in deciding the phosphorylation by cellular nucleoside kinases. [Formula: see text].

Growth and Synthesis of Nucleic Acid and Protein by Excised Radish Cotyledons 1

PubMed Central

Nieman, R. H.; Poulsen, L. L.

1967-01-01

Nutritional and light requirements for growth and synthesis of RNA, DNA, and protein by cotyledons excised from 5-day-old seedlings of Raphanus sativus L. were investigated, and the course of synthesis was followed through the cell cycle. The minimum requirements for a net increase in nucleic acid and protein were sugar, nitrate, and light. The cotyledons used nitrite at low concentration, but not ammonium ion. Light was required for preliminary steps in synthesis of RNA, DNA, and protein, but the actual polymerization reactions occurred in the dark. The cotyledons contained sufficient endogenous growth factors for about half of the cells to complete 1 cycle on a medium of 1% sucrose, 80 mm KNO3. The increase in DNA was limited to about 50% and was accompanied by a comparable increase in cell number. Fresh weight, RNA, and protein tended to increase in proportion to DNA. Growth of the isolated cotyledons commenced with cell enlargement. RNA began to increase after about 4 hours, DNA after about 12. The major increase in protein also began at about 12 hours. The maximum rate of increase for all 3 occurred between 12 and 16 hours. Cell counts indicated that by 28 hours most of the cells which had replicated DNA had also completed cell division. PMID:16656601

Response of cellular stoichiometry and phosphorus storage of the cyanobacteria Aphanizomenon flos-aquae to small-scale turbulence

NASA Astrophysics Data System (ADS)

Li, Zhe; Xiao, Yan; Yang, Jixiang; Li, Chao; Gao, Xia; Guo, Jinsong

2017-11-01

Turbulent mixing, in particular on a small scale, affects the growth of microalgae by changing diffusive sublayers and regulating nutrient fluxes of cells. We tested the nutrient flux hypothesis by evaluating the cellular stoichiometry and phosphorus storage of microalgae under different turbulent mixing conditions. Aphanizomenon flos-aquae were cultivated in different stirring batch reactors with turbulent dissipation rates ranging from 0.001 51 m2/s3 to 0.050 58 m2/s3, the latter being the highest range observed in natural aquatic systems. Samples were taken in the exponential growth phase and compared with samples taken when the reactor was completely stagnant. Results indicate that, within a certain range, turbulent mixing stimulates the growth of A. flos-aquae. An inhibitory effect on growth rate was observed at the higher range. Photosynthesis activity, in terms of maximum effective quantum yield of PSII (the ratio of F v/ F m) and cellular chlorophyll a, did not change significantly in response to turbulence. However, Chl a/C mass ratio and C/N molar ratio, showed a unimodal response under a gradient of turbulent mixing, similar to growth rate. Moreover, we found that increases in turbulent mixing might stimulate respiration rates, which might lead to the use of polyphosphate for the synthesis of cellular constituents. More research is required to test and verify the hypothesis that turbulent mixing changes the diffusive sublayer, regulating the nutrient flux of cells.

Expression of human choline kinase in NIH 3T3 fibroblasts increases the mitogenic potential of insulin and insulin-like growth factor I.

PubMed

Chung, T; Huang, J S; Mukherjee, J J; Crilly, K S; Kiss, Z

2000-05-01

In mammalian cells, growth factors, oncogenes, and carcinogens stimulate phosphocholine (PCho) synthesis by choline kinase (CK), suggesting that PCho may regulate cell growth. To validate the role of PCho in mitogenesis, we determined the effects of insulin, insulin-like growth factor I (IGF-I), and other growth factors on DNA synthesis in NIH 3T3 fibroblast sublines highly expressing human choline kinase (CK) without increasing phosphatidylcholine synthesis. In serum-starved CK expressor cells, insulin and IGF-I stimulated DNA synthesis, p70 S6 kinase (p70 S6K) activity, phosphatidylinositol 3-kinase (PI3K) activity, and activating phosphorylation of p42/p44 mitogen-activated protein kinases (MAPK) to greater extents than in the corresponding vector control cells. Furthermore, the CK inhibitor hemicholinium-3 (HC-3) inhibited insulin- and IGF-I-induced DNA synthesis in the CK overexpressors, but not in the vector control cells. The results indicate that high cellular levels of PCho potentiate insulin- and IGF-I-induced DNA synthesis by MAPK- and p70 S6K-regulated mechanisms.

Effects of Sucrose and Kinetin on Growth and Chlorophyll Synthesis in Tobacco Tissue Cultures 1

PubMed Central

Kaul, K.; Sabharwal, P. S.

1971-01-01

Investigations were carried out on the effects of various combinations of sucrose and kinetin concentrations on growth and chlorophyll production in a green and a nongreen clone of pith callus of Nicotiana tabacum L. It was found that 2 milligrams per liter or higher amounts of kinetin induced greening in the nongreen tissue. The observations suggested that growth of the callus and synthesis of chlorophyll and soluble protein are controlled by relative concentrations of sucrose and kinetin in the medium. Kinetin was found to be inhibitory for chlorophyll synthesis in the green callus. PMID:16657686

Regulation of intestinal mucosal growth by amino acids.

PubMed

Ray, Ramesh M; Johnson, Leonard R

2014-03-01

Amino acids, especially glutamine (GLN) have been known for many years to stimulate the growth of small intestinal mucosa. Polyamines are also required for optimal mucosal growth, and the inhibition of ornithine decarboxylase (ODC), the first rate-limiting enzyme in polyamine synthesis, blocks growth. Certain amino acids, primarily asparagine (ASN) and GLN stimulate ODC activity in a solution of physiological salts. More importantly, their presence is also required before growth factors and hormones such as epidermal growth factor and insulin are able to increase ODC activity. ODC activity is inhibited by antizyme-1 (AZ) whose synthesis is stimulated by polyamines, thus, providing a negative feedback regulation of the enzyme. In the absence of amino acids mammalian target of rapamycin complex 1 (mTORC1) is inhibited, whereas, mTORC2 is stimulated leading to the inhibition of global protein synthesis but increasing the synthesis of AZ via a cap-independent mechanism. These data, therefore, explain why ASN or GLN is essential for the activation of ODC. Interestingly, in a number of papers, AZ has been shown to inhibit cell proliferation, stimulate apoptosis, or increase autophagy. Each of these activities results in decreased cellular growth. AZ binds to and accelerates the degradation of ODC and other proteins shown to regulate proliferation and cell death, such as Aurora-A, Cyclin D1, and Smad1. The correlation between the stimulation of ODC activity and the absence of AZ as influenced by amino acids is high. Not only do amino acids such as ASN and GLN stimulate ODC while inhibiting AZ synthesis, but also amino acids such as lysine, valine, and ornithine, which inhibit ODC activity, increase the synthesis of AZ. The question remaining to be answered is whether AZ inhibits growth directly or whether it acts by decreasing the availability of polyamines to the dividing cells. In either case, evidence strongly suggests that the regulation of AZ synthesis is the

Regulation of the cellular and physiological effects of glutamine.

PubMed

Chwals, Walter J

2004-10-01

Glutamine is the most abundant amino acid in humans and possesses many functions in the body. It is the major transporter of amino-nitrogen between cells and an important fuel source for rapidly dividing cells such as cells of the immune and gastrointestinal systems. It is important in the synthesis of nucleic acids, glutathione, citrulline, arginine, gamma aminobutyric acid, and glucose. It is important for growth, gastrointestinal integrity, acid-base homeostasis, and optimal immune function. The regulation of glutamine levels in cells via glutaminase and glutamine synthetase is discussed. The cellular and physiologic effects of glutamine upon the central nervous system, gastrointestinal function, during metabolic support, and following tissue injury and critical illness is also discussed.

Cellular compartmentalization of secondary metabolism

USDA-ARS?s Scientific Manuscript database

Fungal secondary metabolism is often considered apart from the essential housekeeping functions of the cell. However, there are clear links between fundamental cellular metabolism and the biochemical pathways leading to secondary metabolite synthesis. Besides utilizing key biochemical precursors sh...

African swine fever virus controls the host transcription and cellular machinery of protein synthesis.

PubMed

Sánchez, Elena G; Quintas, Ana; Nogal, Marisa; Castelló, Alfredo; Revilla, Yolanda

2013-04-01

Throughout a viral infection, the infected cell reprograms the gene expression pattern in order to establish a satisfactory antiviral response. African swine fever virus (ASFV), like other complex DNA viruses, sets up a number of strategies to evade the host's defense systems, such as apoptosis, inflammation and immune responses. The capability of the virus to persist in its natural hosts and in domestic pigs, which recover from infection with less virulent isolates, suggests that the virus displays effective mechanisms to escape host defense systems. ASFV has been described to regulate the activation of several transcription factors, thus regulating the activation of specific target genes during ASFV infection. Whereas some reports have concerned about anti-apoptotic ASFV genes and the molecular mechanisms by which ASFV interferes with inducible gene transcription and immune evasion, less is yet known regarding how ASFV regulates the translational machinery in infected cells, although a recent report has shown a mechanism for favored expression of viral genes based on compartmentalization of viral mRNA and ribosomes with cellular translation factors within the virus factory. The viral mechanisms involved both in the regulation of host genes transcription and in the control of cellular protein synthesis are summarized in this review. Copyright © 2012 Elsevier B.V. All rights reserved.

Endoplasmic reticulum mediated signaling in cellular microdomains

PubMed Central

Biwer, Lauren; Isakson, Brant E

2016-01-01

The endoplasmic reticulum (ER) is a prime mediator of cellular signaling due to its functions as an internal cellular store for calcium, as well as a site for synthesis of proteins and lipids. Its peripheral network of sheets and tubules facilitate calcium and lipid signaling, especially in areas of the cell that are more distant to the main cytoplasmic network. Specific membrane proteins shape the peripheral ER architecture and influence the network stability in order to project into restricted spaces. The signaling microdomains are anatomically separate from the cytoplasm as a whole and exhibit localized protein, ion channel and cytoskeletal element expression. Signaling can also occur between the ER and other organelles, such as the Golgi or mitochondria. Lipids made in the ER membrane can be sent to the Golgi via specialized transfer proteins and specific phospholipid synthases are enriched at ER-mitochondria junctions to more efficiently expedite phospholipid transfer. As a hub for protein and lipid synthesis, a store for intracellular calcium [Ca2+]i, and a mediator of cellular stress, the ER is an important cellular organelle. Its ability to organize into tubules and project into restricted spaces allows for discrete and temporal signaling, which is important for cellular physiology and organism homeostasis. PMID:26973141

Regulation of Intestinal Mucosal Growth by Amino Acids

PubMed Central

Ray, Ramesh M.; Johnson, Leonard R.

2013-01-01

Amino acids, especially glutamine (GLN) have been known for many years to stimulate the growth of small intestinal mucosa. Polyamines are also required for optimal mucosal growth, and the inhibition of ornithine decarboxylase (ODC), the first rate-limiting enzyme in polyamine synthesis, blocks growth. Certain amino acids, primarily asparagine (ASN) and GLN stimulate ODC activity in a solution of physiological salts. More importantly, their presence is also required before growth factors and hormones such as EGF and insulin are able to increase ODC activity. ODC activity is inhibited by antizyme-1 (AZ) whose synthesis is stimulated by polyamines, thus, providing a negative feedback regulation of the enzyme. In the absence of amino acids mammalian target of rapamycin complex 1 (mTORC1) is inhibited, whereas, mTORC2 is stimulated leading to the inhibition of global protein synthesis but increasing the synthesis of AZ via a cap-independent mechanism. These data, therefore, explain why ASN or GLN is essential for the activation of ODC. Interestingly, in a number of papers, AZ has been shown to inhibit cell proliferation, stimulate apoptosis or increase autophagy. Each of these activities results in decreased cellular growth. AZ binds to and accelerates the degradation of ODC and other proteins shown to regulate proliferation and cell death, such as Aurora-A, Cyclin D1 and Smad1. The correlation between the stimulation of ODC activity and the absence of AZ as influenced by amino acids is high. Not only do amino acids such as ASN and GLN stimulate ODC while inhibiting AZ synthesis, but also amino acids such as lysine, valine and ornithine, which inhibit ODC activity, increase the synthesis of AZ. The question remaining to be answered is whether AZ inhibits growth directly or whether it acts by decreasing the availability of polyamines to the dividing cells. In either case, evidence strongly suggests that the regulation of AZ synthesis is the mechanism through which amino

Regulation of adult cardiocyte growth: effects of active and passive mechanical loading

NASA Technical Reports Server (NTRS)

Decker, M. L.; Janes, D. M.; Barclay, M. M.; Harger, L.; Decker, R. S.

1997-01-01

Fluctuations in hemodynamic load have been documented to modulate contractile protein turnover and myofibrillar structure in the heart; however, the relative importance of active and passive loading in regulating adult cardiocyte growth remains unresolved. To address this issue at the cellular level, adult feline cardiocytes were cultured either on Silastic membranes or plastic surfaces. Cardiocyte-laden membranes were stretched 10% of their rest length to enhance passive loading, whereas heart cells cultured on plastic or Silastic were field stimulated at 1 Hz to mimic active loading. Turnover of contractile proteins and structural integrity of the contractile-cytoskeletal apparatus were monitored for periods ranging from 4 to 72 h. Active and passive loading elevated contractile protein synthesis nearly equally (approximately 50%) and promoted the attachment of remodeled myofibrils to vinculin-positive focal contacts and/or costameres during the first 24 h of loading. Thereafter, rates of contractile protein synthesis returned to control values in passively stretched heart cells but remained elevated in field-stimulated cultures. The fractional rate of growth was increased significantly (approximately 8%/day) in electrically paced cells, whereas in passively stretched cardiocytes the growth rate rose only modestly (approximately 2%/day). Changes in the rate of myocyte growth appeared more closely correlated with the development of focal contacts and myofibril remodeling than with changes in myofibrillar protein turnover per se. 2,3-Butanedione monoxime, nifedipine, and, to a lesser extent, ryanodine blocked field-stimulated contractile protein synthesis and myofibrillar remodeling but had no impact on protein turnover or myofibril reassembly in passively loaded cardiocytes. The results of these experiments imply that both active and passive loading stimulate contractile protein turnover and myofibril remodeling, but the generation of active tension accelerates

Regulation of adult cardiocyte growth: effects of active and passive mechanical loading.

PubMed

Decker, M L; Janes, D M; Barclay, M M; Harger, L; Decker, R S

1997-06-01

Fluctuations in hemodynamic load have been documented to modulate contractile protein turnover and myofibrillar structure in the heart; however, the relative importance of active and passive loading in regulating adult cardiocyte growth remains unresolved. To address this issue at the cellular level, adult feline cardiocytes were cultured either on Silastic membranes or plastic surfaces. Cardiocyte-laden membranes were stretched 10% of their rest length to enhance passive loading, whereas heart cells cultured on plastic or Silastic were field stimulated at 1 Hz to mimic active loading. Turnover of contractile proteins and structural integrity of the contractile-cytoskeletal apparatus were monitored for periods ranging from 4 to 72 h. Active and passive loading elevated contractile protein synthesis nearly equally (approximately 50%) and promoted the attachment of remodeled myofibrils to vinculin-positive focal contacts and/or costameres during the first 24 h of loading. Thereafter, rates of contractile protein synthesis returned to control values in passively stretched heart cells but remained elevated in field-stimulated cultures. The fractional rate of growth was increased significantly (approximately 8%/day) in electrically paced cells, whereas in passively stretched cardiocytes the growth rate rose only modestly (approximately 2%/day). Changes in the rate of myocyte growth appeared more closely correlated with the development of focal contacts and myofibril remodeling than with changes in myofibrillar protein turnover per se. 2,3-Butanedione monoxime, nifedipine, and, to a lesser extent, ryanodine blocked field-stimulated contractile protein synthesis and myofibrillar remodeling but had no impact on protein turnover or myofibril reassembly in passively loaded cardiocytes. The results of these experiments imply that both active and passive loading stimulate contractile protein turnover and myofibril remodeling, but the generation of active tension accelerates

Transforming growth factor-beta1 mediates cellular response to DNA damage in situ

NASA Technical Reports Server (NTRS)

Ewan, Kenneth B.; Henshall-Powell, Rhonda L.; Ravani, Shraddha A.; Pajares, Maria Jose; Arteaga, Carlos; Warters, Ray; Akhurst, Rosemary J.; Barcellos-Hoff, Mary Helen

2002-01-01

Transforming growth factor (TGF)-beta1 is rapidly activated after ionizing radiation, but its specific role in cellular responses to DNA damage is not known. Here we use Tgfbeta1 knockout mice to show that radiation-induced apoptotic response is TGF-beta1 dependent in the mammary epithelium, and that both apoptosis and inhibition of proliferation in response to DNA damage decrease as a function of TGF-beta1 gene dose in embryonic epithelial tissues. Because apoptosis in these tissues has been shown previously to be p53 dependent, we then examined p53 protein activation. TGF-beta1 depletion, by either gene knockout or by using TGF-beta neutralizing antibodies, resulted in decreased p53 Ser-18 phosphorylation in irradiated mammary gland. These data indicate that TGF-beta1 is essential for rapid p53-mediated cellular responses that mediate cell fate decisions in situ.

New insights into the cellular mechanisms of plant growth at elevated atmospheric carbon dioxide.

PubMed

Gamage, Dananjali; Thompson, Michael; Sutherland, Mark; Hirotsu, Naoki; Makino, Amane; Seneweera, Saman

2018-04-02

Rising atmospheric carbon dioxide concentration ([CO 2 ]) significantly influences plant growth, development and biomass. Increased photosynthesis rate, together with lower stomatal conductance, have been identified as the key factors that stimulate plant growth at elevated [CO 2 ] (e[CO 2 ]). However, variations in photosynthesis and stomatal conductance alone cannot fully explain the dynamic changes in plant growth. Stimulation of photosynthesis at e[CO 2 ] is always associated with post-photosynthetic secondary metabolic processes that include carbon and nitrogen metabolism, cell cycle functions and hormonal regulation. Most studies have focused on photosynthesis and stomatal conductance in response to e[CO 2 ], despite the emerging evidence of e[CO 2 ]'s role in moderating secondary metabolism in plants. In this review, we briefly discuss the effects of e[CO 2 ] on photosynthesis and stomatal conductance and then focus on the changes in other cellular mechanisms and growth processes at e[CO 2 ] in relation to plant growth and development. Finally, knowledge gaps in understanding plant growth responses to e[CO 2 ] have been identified with the aim of improving crop productivity under a CO 2 rich atmosphere. This article is protected by copyright. All rights reserved.

Rapid-synthesis of zeolite T via sonochemical-assisted hydrothermal growth method.

PubMed

Jusoh, Norwahyu; Yeong, Yin Fong; Mohamad, Maisarah; Lau, Kok Keong; M Shariff, Azmi

2017-01-01

Sonochemical-assisted method has been identified as one of the potential pre-treatment methods which could reduce the formation duration of zeolite as well as other microporous and mesoporous materials. In the present work, zeolite T was synthesized via sonochemical-assisted pre-treatment prior to hydrothermal growth. The durations for sonochemical-assisted pre-treatment were varied from 30min to 90min. Meanwhile, the hydrothermal growth durations were ranged from 0.5 to 3days. The physicochemical properties of the resulting samples were characterized using XRD, FESEM, FTIR and BET. As verified by XRD, the samples synthesized via hydrothermal growth durations of 1, 2 and 3days and sonochemical-assisted pre-treatment durations of 60min and 90min demonstrated zeolite T structure. The samples which underwent sonochemical-assisted pre-treatment duration of 60min yielded higher crystallinity with negligible change of zeolite T morphology. Overall, the lengthy synthesis duration of zeolite T has been successfully reduced from 7days to 1day by applying sonochemical-assisted pre-treatment of 60min, while synthesis duration of 0.5days via sonochemical-assisted pre-treatment of 60min was not sufficient to produce zeolite T structure. Copyright © 2016 Elsevier B.V. All rights reserved.

Remobilization of Phytol from Chlorophyll Degradation Is Essential for Tocopherol Synthesis and Growth of Arabidopsis

PubMed Central

vom Dorp, Katharina; Hölzl, Georg; Plohmann, Christian; Eisenhut, Marion; Abraham, Marion

2015-01-01

Phytol from chlorophyll degradation can be phosphorylated to phytyl-phosphate and phytyl-diphosphate, the substrate for tocopherol (vitamin E) synthesis. A candidate for the phytyl-phosphate kinase from Arabidopsis thaliana (At1g78620) was identified via a phylogeny-based approach. This gene was designated VITAMIN E DEFICIENT6 (VTE6) because the leaves of the Arabidopsis vte6 mutants are tocopherol deficient. The vte6 mutant plants are incapable of photoautotrophic growth. Phytol and phytyl-phosphate accumulate, and the phytyl-diphosphate content is strongly decreased in vte6 leaves. Phytol feeding and enzyme assays with Arabidopsis and recombinant Escherichia coli cells demonstrated that VTE6 has phytyl-P kinase activity. Overexpression of VTE6 resulted in increased phytyl-diphosphate and tocopherol contents in seeds, indicating that VTE6 encodes phytyl-phosphate kinase. The severe growth retardation of vte6 mutants was partially rescued by introducing the phytol kinase mutation vte5. Double mutant plants (vte5 vte6) are tocopherol deficient and contain more chlorophyll, but reduced amounts of phytol and phytyl-phosphate compared with vte6 mutants, suggesting that phytol or phytyl-phosphate are detrimental to plant growth. Therefore, VTE6 represents the missing phytyl-phosphate kinase, linking phytol release from chlorophyll with tocopherol synthesis. Moreover, tocopherol synthesis in leaves depends on phytol derived from chlorophyll, not on de novo synthesis of phytyl-diphosphate from geranylgeranyl-diphosphate. PMID:26452599

DGK1-encoded Diacylglycerol Kinase Activity Is Required for Phospholipid Synthesis during Growth Resumption from Stationary Phase in Saccharomyces cerevisiae*

PubMed Central

Fakas, Stylianos; Konstantinou, Chrysanthos; Carman, George M.

2011-01-01

In the yeast Saccharomyces cerevisiae, triacylglycerol mobilization for phospholipid synthesis occurs during growth resumption from stationary phase, and this metabolism is essential in the absence of de novo fatty acid synthesis. In this work, we provide evidence that DGK1-encoded diacylglycerol kinase activity is required to convert triacylglycerol-derived diacylglycerol to phosphatidate for phospholipid synthesis. Cells lacking diacylglycerol kinase activity (e.g. dgk1Δ mutation) failed to resume growth in the presence of the fatty acid synthesis inhibitor cerulenin. Lipid analysis data showed that dgk1Δ mutant cells did not mobilize triacylglycerol for membrane phospholipid synthesis and accumulated diacylglycerol. The dgk1Δ phenotypes were partially complemented by preventing the formation of diacylglycerol by the PAH1-encoded phosphatidate phosphatase and by channeling diacylglycerol to phosphatidylcholine via the Kennedy pathway. These observations, coupled to an inhibitory effect of dioctanoyl-diacylglycerol on the growth of wild type cells, indicated that diacylglycerol kinase also functions to alleviate diacylglycerol toxicity. PMID:21071438

Stochastic cellular automata model of neurosphere growth: Roles of proliferative potential, contact inhibition, cell death, and phagocytosis.

PubMed

Sipahi, Rifat; Zupanc, Günther K H

2018-05-14

Neural stem and progenitor cells isolated from the central nervous system form, under specific culture conditions, clonal cell clusters known as neurospheres. The neurosphere assay has proven to be a powerful in vitro system to study the behavior of such cells and the development of their progeny. However, the theory of neurosphere growth has remained poorly understood. To overcome this limitation, we have, in the present paper, developed a cellular automata model, with which we examined the effects of proliferative potential, contact inhibition, cell death, and clearance of dead cells on growth rate, final size, and composition of neurospheres. Simulations based on this model indicated that the proliferative potential of the founder cell and its progenitors has a major influence on neurosphere size. On the other hand, contact inhibition of proliferation limits the final size, and reduces the growth rate, of neurospheres. The effect of this inhibition is particularly dramatic when a stem cell becomes encapsulated by differentiated or other non-proliferating cells, thereby suppressing any further mitotic division - despite the existing proliferative potential of the stem cell. Conversely, clearance of dead cells through phagocytosis is predicted to accelerate growth by reducing contact inhibition. A surprising prediction derived from our model is that cell death, while resulting in a decrease in growth rate and final size of neurospheres, increases the degree of differentiation of neurosphere cells. It is likely that the cellular automata model developed as part of the present investigation is applicable to the study of tissue growth in a wide range of systems. Copyright © 2018 Elsevier Ltd. All rights reserved.

Emergence of robust growth laws from optimal regulation of ribosome synthesis.

PubMed

Scott, Matthew; Klumpp, Stefan; Mateescu, Eduard M; Hwa, Terence

2014-08-22

Bacteria must constantly adapt their growth to changes in nutrient availability; yet despite large-scale changes in protein expression associated with sensing, adaptation, and processing different environmental nutrients, simple growth laws connect the ribosome abundance and the growth rate. Here, we investigate the origin of these growth laws by analyzing the features of ribosomal regulation that coordinate proteome-wide expression changes with cell growth in a variety of nutrient conditions in the model organism Escherichia coli. We identify supply-driven feedforward activation of ribosomal protein synthesis as the key regulatory motif maximizing amino acid flux, and autonomously guiding a cell to achieve optimal growth in different environments. The growth laws emerge naturally from the robust regulatory strategy underlying growth rate control, irrespective of the details of the molecular implementation. The study highlights the interplay between phenomenological modeling and molecular mechanisms in uncovering fundamental operating constraints, with implications for endogenous and synthetic design of microorganisms. © 2014 The Authors. Published under the terms of the CC BY 4.0 license.

Aminoimidazole Carboxamide Ribotide Exerts Opposing Effects on Thiamine Synthesis in Salmonella enterica

PubMed Central

Bazurto, Jannell V.; Heitman, Nicholas J.

2015-01-01

ABSTRACT In Salmonella enterica, the thiamine biosynthetic intermediate 5-aminoimidazole ribotide (AIR) can be synthesized de novo independently of the early purine biosynthetic reactions. This secondary route to AIR synthesis is dependent on (i) 5-amino-4-imidazolecarboxamide ribotide (AICAR) accumulation, (ii) a functional phosphoribosylaminoimidazole-succinocarboxamide (SAICAR) synthetase (PurC; EC 6.3.2.6), and (iii) methionine and lysine in the growth medium. Studies presented here show that AICAR is a direct precursor to AIR in vivo. PurC-dependent conversion of AICAR to AIR was recreated in vitro. Physiological studies showed that exogenous nutrients (e.g., methionine and lysine) antagonize the inhibitory effects of AICAR on the ThiC reaction and decreased the cellular thiamine requirement. Finally, genetic results identified multiple loci that impacted the effect of AICAR on thiamine synthesis and implicated cellular aspartate levels in AICAR-dependent AIR synthesis. Together, the data here clarify the mechanism that allows conditional growth of a strain lacking the first five biosynthetic enzymes, and they provide additional insights into the complexity of the metabolic network and its plasticity. IMPORTANCE In bacteria, the pyrimidine moiety of thiamine is derived from aminoimidazole ribotide (AIR), an intermediate in purine biosynthesis. A previous study described conditions under which AIR synthesis is independent of purine biosynthesis. This work is an extension of that previous study and describes a new synthetic pathway to thiamine that depends on a novel thiamine precursor and a secondary activity of the biosynthetic enzyme PurC. These findings provide mechanistic details of redundancy in the synthesis of a metabolite that is essential for nucleotide and coenzyme biosynthesis. Metabolic modifications that allow the new pathway to function or enhance it are also described. PMID:26100042

Room temperature growth of ZnO nanorods by hydrothermal synthesis

NASA Astrophysics Data System (ADS)

Tateyama, Hiroki; Zhang, Qiyan; Ichikawa, Yo

2018-05-01

The effect of seed layer morphology on ZnO nanorod growth at room temperature was studied via hydrothermal synthesis on seed layers with different thicknesses and further annealed at different temperatures. The change in the thickness and annealing temperature enabled us to control over a diameter of ZnO nanorods which are attributed to the changing of crystallinity and roughness of the seed layers.

Understanding Self-Catalyzed Epitaxial Growth of III-V Nanowires toward Controlled Synthesis.

PubMed

Zi, Yunlong; Suslov, Sergey; Yang, Chen

2017-02-08

The self-catalyzed growth of III-V nanowires has drawn plenty of attention due to the potential of integration in current Si-based technologies. The homoparticle-assisted vapor-liquid-solid growth mechanism has been demonstrated for self-catalyzed III-V nanowire growth. However, the understandings of the preferred growth sites of these nanowires are still limited, which obstructs the controlled synthesis and the applications of self-catalyzed nanowire arrays. Here, we experimentally demonstrated that thermally created pits could serve as the preferred sites for self-catalyzed InAs nanowire growth. On that basis, we performed a pregrowth annealing strategy to promote the nanowire density by enhancing the pits formation on the substrate surface and enable the nanowire growth on the substrate that was not capable to facilitate the growth. The discovery of the preferred self-catalyzed nanowire growth sites and the pregrowth annealing strategy have shown great potentials for controlled self-catalyzed III-V nanowire array growth with preferred locations and density.

Cellular Development Associated with Induced Mycotoxin Synthesis in the Filamentous Fungus Fusarium graminearum

PubMed Central

Menke, Jon; Weber, Jakob; Broz, Karen; Kistler, H. Corby

2013-01-01

Several species of the filamentous fungus Fusarium colonize plants and produce toxic small molecules that contaminate agricultural products, rendering them unsuitable for consumption. Among the most destructive of these species is F. graminearum, which causes disease in wheat and barley and often infests the grain with harmful trichothecene mycotoxins. Synthesis of these secondary metabolites is induced during plant infection or in culture in response to chemical signals. Our results show that trichothecene biosynthesis involves a complex developmental process that includes dynamic changes in cell morphology and the biogenesis of novel subcellular structures. Two cytochrome P-450 oxygenases (Tri4p and Tri1p) involved in early and late steps in trichothecene biosynthesis were tagged with fluorescent proteins and shown to co-localize to vesicles we provisionally call “toxisomes.” Toxisomes, the inferred site of trichothecene biosynthesis, dynamically interact with motile vesicles containing a predicted major facilitator superfamily protein (Tri12p) previously implicated in trichothecene export and tolerance. The immediate isoprenoid precursor of trichothecenes is the primary metabolite farnesyl pyrophosphate. Changes occur in the cellular localization of the isoprenoid biosynthetic enzyme HMG CoA reductase when cultures non-induced for trichothecene biosynthesis are transferred to trichothecene biosynthesis inducing medium. Initially localized in the cellular endomembrane system, HMG CoA reductase, upon induction of trichothecene biosynthesis, increasingly is targeted to toxisomes. Metabolic pathways of primary and secondary metabolism thus may be coordinated and co-localized under conditions when trichothecene biosynthesis occurs. PMID:23667578

Impact of labile metal nanoparticles on cellular homeostasis. Current developments in imaging, synthesis and applications.

PubMed

Chevallet, Mireille; Veronesi, Giulia; Fuchs, Alexandra; Mintz, Elisabeth; Michaud-Soret, Isabelle; Deniaud, Aurélien

2017-06-01

The use of nanomaterials is constantly increasing in electronics, cosmetics, food additives, and is emerging in advanced biomedical applications such as theranostics, bio-imaging and therapeutics. However their safety raises concerns and requires appropriate methods to analyze their fate in vivo. In this review, we describe the current knowledge about the toxicity of labile metal (ZnO, CuO and Ag) nanoparticles (NPs) both at the organism and cellular levels, and describe the pathways that are triggered to maintain cellular homeostasis. We also describe advanced elemental imaging approaches to analyze intracellular NP fate. Finally, we open the discussion by presenting recent developments in terms of synthesis and applications of Ag and CuO NPs. Labile metal nanoparticles (MeNPs) release metal ions that trigger a cellular response involving biomolecules binding to the ions followed by regulation of the redox balance. In addition, specific mechanisms are set up by the cell in response to physiological ions such as Cu(I) and Zn(II). Among all types of NPs, labile MeNPs induce the strongest inflammatory responses which are most probably due to the combined effects of the NPs and of its released ions. Interestingly, recent developments in imaging technologies enable the intracellular visualization of both the NPs and their ions and promise new insights into nanoparticle fate and toxicity. The exponential use of nanotechnologies associated with the difficulties of assessing their impact on health and the environment has prompted scientists to develop novel methodologies to characterize these nanoobjects in a biological context. Copyright © 2016 Elsevier B.V. All rights reserved.

Water-Assisted Highly Efficient Synthesis of Impurity-Free Single-Walled Carbon Nanotubes-``Super-Growth''

NASA Astrophysics Data System (ADS)

Hata, Kenji

2005-03-01

We demonstrate an extremely efficient chemical vapour deposition synthesis of single-walled carbon nanotubes where the activity and lifetime of the catalysts are enhanced by water [1]. Water-stimulated enhanced catalytic activity results in massive growth of super-dense and vertically-aligned nanotube forests with heights up to 2.5 millimeters that can be easily separated from the catalysts, providing nanotube material with carbon purity above 99.98%. Moreover, patterned highly organized intrinsic nanotube structures were successfully fabricated. The water-assisted synthesis method addresses many critical problems that currently plague carbon nanotube synthesis. [1] K. Hata, et al., Science, 306, 1362 (2004).

Compound Synthesis or Growth and Development of Roots/Stomata Regulate Plant Drought Tolerance or Water Use Efficiency/Water Uptake Efficiency.

PubMed

Meng, Lai-Sheng

2018-04-11

Water is crucial to plant growth and development because it serves as a medium for all cellular functions. Thus, the improvement of plant drought tolerance or water use efficiency/water uptake efficiency is important in modern agriculture. In this review, we mainly focus on new genetic factors for ameliorating drought tolerance or water use efficiency/water uptake efficiency of plants and explore the involvement of these genetic factors in the regulation of improving plant drought tolerance or water use efficiency/water uptake efficiency, which is a result of altered stomata density and improving root systems (primary root length, hair root growth, and lateral root number) and enhanced production of osmotic protectants, which is caused by transcription factors, proteinases, and phosphatases and protein kinases. These results will help guide the synthesis of a model for predicting how the signals of genetic and environmental stress are integrated at a few genetic determinants to control the establishment of either water use efficiency or water uptake efficiency. Collectively, these insights into the molecular mechanism underpinning the control of plant drought tolerance or water use efficiency/water uptake efficiency may aid future breeding or design strategies to increase crop yield.

Cellular solidification in a monotectic system

NASA Technical Reports Server (NTRS)

Kaukler, W. F.; Curreri, P. A.

1987-01-01

Succinonitrile-glycerol, SN-G, transparent organic monotectic alloy is studied with particular attention to cellular growth. The phase diagram is determined, near the monotectic composition, with greater accuracy than previous studies. A solidification interface stability diagram is determined for planar growth. The planar-to-cellular transition is compared to predictions from the Burton, Primm, Schlichter theory. A new technique to determine the solute segregation by Fourier transform infrared spectroscopy is developed. Proposed models that involve the cellular interface for alignment of monotectic second-phase spheres or rods are compared with observations.

On the feasibility of growth-coupled product synthesis in microbial strains.

PubMed

Klamt, Steffen; Mahadevan, Radhakrishnan

2015-07-01

Enforcing obligate coupling of growth with synthesis of a desired product has become a key principle for metabolic engineering of microbial production strains. Various methods from stoichiometric and constraint-based modeling have been developed to calculate intervention strategies by which a given microorganism can only grow if it synthesizes a desired compound as a mandatory by-product. However, growth-coupled synthesis is not necessarily feasible for every compound of a metabolic network and no rigorous criterion is currently known to test feasibility of coupled product and biomass formation (before searching for suitable intervention strategies). In this work, we show which properties a network must fulfill such that strain designs guaranteeing coupled biomass and product synthesis can exist at all. In networks without flux bounds, coupling is feasible if and only if an elementary mode exists that leads to formation of both biomass and product. Setting flux boundaries leads to more complicated inhomogeneous problems. Making use of the concept of elementary (flux) vectors, a generalization of elementary modes, a criterion for feasibility can also be derived for this situation. We applied our criteria to a metabolic model of Escherichia coli and determined for each metabolite, whether its net production can be coupled with biomass synthesis and calculated the maximal (guaranteed) coupling yield. The somewhat surprising result is that, under aerobic conditions, coupling is indeed possible for each carbon metabolite of the central metabolism. This also holds true for most metabolites under anaerobic conditions but consideration of ATP maintenance requirements implies infeasibility of coupling for certain compounds. On the other hand, ATP maintenance may also increase the maximal coupling yield for some metabolites. Overall, our work provides important insights and novel tools for a central problem of computational strain design. Copyright © 2015 International

Cellular and dendritic growth in a binary melt - A marginal stability approach

NASA Technical Reports Server (NTRS)

Laxmanan, V.

1986-01-01

A simple model for the constrained growth of an array of cells or dendrites in a binary alloy in the presence of an imposed positive temperature gradient in the liquid is proposed, with the dendritic or cell tip radius calculated using the marginal stability criterion of Langer and Muller-Krumbhaar (1977). This approach, an approach adopting the ad hoc assumption of minimum undercooling at the cell or dendrite tip, and an approach based on the stability criterion of Trivedi (1980) all predict tip radii to within 30 percent of each other, and yield a simple relationship between the tip radius and the growth conditions. Good agreement is found between predictions and data obtained in a succinonitrile-acetone system, and under the present experimental conditions, the dendritic tip stability parameter value is found to be twice that obtained previously, possibly due to a transition in morphology from a cellular structure with just a few side branches, to a more fully developed dendritic structure.

Cross Talk between Nucleotide Synthesis Pathways with Cellular Immunity in Constraining Hepatitis E Virus Replication

PubMed Central

Wang, Yijin; Wang, Wenshi; Xu, Lei; Zhou, Xinying; Shokrollahi, Ehsan; Felczak, Krzysztof; van der Laan, Luc J. W.; Pankiewicz, Krzysztof W.; Sprengers, Dave; Raat, Nicolaas J. H.; Metselaar, Herold J.; Peppelenbosch, Maikel P.

2016-01-01

Viruses are solely dependent on host cells to propagate; therefore, understanding virus-host interaction is important for antiviral drug development. Since de novo nucleotide biosynthesis is essentially required for both host cell metabolism and viral replication, specific catalytic enzymes of these pathways have been explored as potential antiviral targets. In this study, we investigated the role of different enzymatic cascades of nucleotide biosynthesis in hepatitis E virus (HEV) replication. By profiling various pharmacological inhibitors of nucleotide biosynthesis, we found that targeting the early steps of the purine biosynthesis pathway led to the enhancement of HEV replication, whereas targeting the later step resulted in potent antiviral activity via the depletion of purine nucleotide. Furthermore, the inhibition of the pyrimidine pathway resulted in potent anti-HEV activity. Interestingly, all of these inhibitors with anti-HEV activity concurrently triggered the induction of antiviral interferon-stimulated genes (ISGs). Although ISGs are commonly induced by interferons via the JAK-STAT pathway, their induction by nucleotide synthesis inhibitors is completely independent of this classical mechanism. In conclusion, this study revealed an unconventional novel mechanism of cross talk between nucleotide biosynthesis pathways and cellular antiviral immunity in constraining HEV infection. Targeting particular enzymes in nucleotide biosynthesis represents a viable option for antiviral drug development against HEV. HEV is the most common cause of acute viral hepatitis worldwide and is also associated with chronic hepatitis, especially in immunocompromised patients. Although often an acute and self-limiting infection in the general population, HEV can cause severe morbidity and mortality in certain patients, a problem compounded by the lack of FDA-approved anti-HEV medication available. In this study, we have investigated the role of the nucleotide synthesis pathway

Kisspeptin-10 induces endothelial cellular senescence and impaired endothelial cell growth.

PubMed

Usui, Sayaka; Iso, Yoshitaka; Sasai, Masahiro; Mizukami, Takuya; Mori, Hiroyoshi; Watanabe, Takuya; Shioda, Seiji; Suzuki, Hiroshi

2014-07-01

The KPs (kisspeptins) are a family of multifunctional peptides with established roles in cancer metastasis, puberty and vasoconstriction. The effects of KPs on endothelial cells have yet to be determined. The aim of the present study was to investigate the effects of KP-10 on endothelial cell growth and the mechanisms underlying those effects. The administration of recombinant KP-10 into the hindlimbs of rats with ischaemia significantly impaired blood flow recovery, as shown by laser Doppler, and capillary growth, as shown using histology, compared with the controls. HUVECs (human umbilical vein endothelial cells) express the KP receptor and were treated with KP-10 in culture studies. KP-10 inhibited endothelial cell tube formation and proliferation in a significant and dose-dependent manner. The HUVECs treated with KP exhibited the senescent phenotype, as determined using a senescence-associated β-galactosidase assay, cell morphology analysis, and decreased Sirt1 (sirtuin 1) expression and increased p53 expression shown by Western blot analysis. Intriguingly, a pharmacological Rho kinase inhibitor, Y-27632, was found to increase the proliferation of HUVECs and to reduce the number of senescent phenotype cells affected by KP-10. In conclusion, KP-10 suppressed endothelial cells growth both in vivo and in vitro in the present study. The adverse effect of KP on endothelial cells was attributable, at least in part, to the induction of cellular senescence.

Sulfur partitioning between glutathione and protein synthesis determines plant growth.

PubMed

Speiser, Anna; Silbermann, Marleen; Dong, Yihan; Haberland, Stefan; Uslu, Veli Vural; Wang, Shanshan; Bangash, Sajid A K; Reichelt, Michael; Meyer, Andreas J; Wirtz, Markus; Hell, Ruediger

2018-05-11

Photoautotrophic organisms must efficiently allocate their resources between stress-response pathways and growth-promoting pathways to be successful in a constantly changing environment. In this study, we addressed the coordination of sulfur flux between biosynthesis of the reactive oxygen species scavenger glutathione (GSH) and protein translation as one example of a central resource allocation switch. We crossed the Arabidopsis (Arabidopsis thaliana) GSH synthesis depleted cadmium-sensitive cad2-1 mutant, which lacks glutamate Cys ligase, into the sulfite reductase (SiR) sir1-1 mutant, which suffers from a significantly decreased flux of sulfur into cysteine and is consequently retarded in growth. Surprisingly, depletion of GSH synthesis promoted the growth of the sir1-1 cad2-1 double mutant (s1c2) when compared to sir1-1. Determination of GSH levels and in vivo live-cell imaging of the reduction-oxidation sensitive green fluorescent protein (roGFP2)-sensor demonstrated significant oxidation of the plastidic GSH redox-potential in cad2-1 and s1c2. This oxidized GSH redox-potential aligned with significant activation of plastid-localized sulfate reduction and a significantly higher flux of sulfur into proteins. The specific activation of the serine/threonine sensor kinase Target Of Rapamycin (TOR) in cad2-1 and s1c2 was the trigger for reallocation of cysteine from GSH biosynthesis into protein translation. Activation of TOR in s1c2 enhanced ribosome abundance and partially rescued the decreased meristematic activity observed in sir1-1 mutants. Therefore, we found that the coordination of sulfur flux between glutathione biosynthesis and protein translation determines growth via regulation of TOR. {copyright, serif} 2018 American Society of Plant Biologists. All rights reserved.

Effect of pH on the extra cellular synthesis of gold and silver nanoparticles by Saccharomyces cerevisae.

PubMed

Lim, Hyun-Ah; Mishra, Amrita; Yun, Soon-Il

2011-01-01

In the present study, the synthesis of gold and silver nanoparticles was investigated using the culture supernatant broth of the yeast Saccharomyces cerevisae. Gold nanoparticles were formed within 24 hours of gold ion coming in contact with the culture supernatant broth. In case of silver the reduction process took 48 hours. The synthesized nanoparticles were investigated by UV-Visible spectroscopy. Distinct surface plasmon peaks were observed at 540 nm and 415 nm for gold and silver nanoparticles respectively. Bio-TEM micrographs of the synthesized nanoparticles indicated that the particles were well dispersed and near spherical in shape. The size range of the gold and silver nanoparticles was around 20-100 nm and 5-20 nm respectively. XRD patterns showed the presence of three distinct peaks corresponding to gold and silver nanoparticles respectively. A pH range of 4 to 6 and 8 to 10 favored optimum synthesis of gold and silver nanoparticles respectively. The process of reduction being extra cellular could be used in future for downstream processing in an eco friendly manner.

PAH1-encoded Phosphatidate Phosphatase Plays a Role in the Growth Phase- and Inositol-mediated Regulation of Lipid Synthesis in Saccharomyces cerevisiae*

PubMed Central

Pascual, Florencia; Soto-Cardalda, Aníbal; Carman, George M.

2013-01-01

In the yeast Saccharomyces cerevisiae, the synthesis of phospholipids in the exponential phase of growth occurs at the expense of the storage lipid triacylglycerol. As exponential phase cells progress into the stationary phase, the synthesis of triacylglycerol occurs at the expense of phospholipids. Early work indicates a role of the phosphatidate phosphatase (PAP) in this metabolism; the enzyme produces the diacylglycerol needed for the synthesis of triacylglycerol and simultaneously controls the level of phosphatidate for the synthesis of phospholipids. Four genes (APP1, DPP1, LPP1, and PAH1) encode PAP activity in yeast, and it has been unclear which gene is responsible for the synthesis of triacylglycerol throughout growth. An analysis of lipid synthesis and composition, as well as PAP activity in various PAP mutant strains, showed the essential role of PAH1 in triacylglycerol synthesis throughout growth. Pah1p is a phosphorylated enzyme whose in vivo function is dependent on its dephosphorylation by the Nem1p-Spo7p protein phosphatase complex. nem1Δ mutant cells exhibited defects in triacylglycerol synthesis and lipid metabolism that mirrored those imparted by the pah1Δ mutation, substantiating the importance of Pah1p dephosphorylation throughout growth. An analysis of cells bearing PPAH1-lacZ and PPAH1-DPP1 reporter genes showed that PAH1 expression was induced throughout growth and that the induction in the stationary phase was stimulated by inositol supplementation. A mutant analysis indicated that the Ino2p/Ino4p/Opi1p regulatory circuit and transcription factors Gis1p and Rph1p mediated this regulation. PMID:24196957

Mps1 (Monopolar Spindle 1) Protein Inhibition Affects Cellular Growth and Pro-Embryogenic Masses Morphology in Embryogenic Cultures of Araucaria angustifolia (Araucariaceae).

PubMed

Douétts-Peres, Jackellinne C; Cruz, Marco Antônio L; Reis, Ricardo S; Heringer, Angelo S; de Oliveira, Eduardo A G; Elbl, Paula M; Floh, Eny I S; Silveira, Vanildo; Santa-Catarina, Claudete

2016-01-01

Somatic embryogenesis has been shown to be an efficient tool for studying processes based on cell growth and development. The fine regulation of the cell cycle is essential for proper embryo formation during the process of somatic embryogenesis. The aims of the present work were to identify and perform a structural and functional characterization of Mps1 and to analyze the effects of the inhibition of this protein on cellular growth and pro-embryogenic mass (PEM) morphology in embryogenic cultures of A. angustifolia. A single-copy Mps1 gene named AaMps1 was retrieved from the A. angustifolia transcriptome database, and through a mass spectrometry approach, AaMps1 was identified and quantified in embryogenic cultures. The Mps1 inhibitor SP600125 (10 μM) inhibited cellular growth and changed PEMs, and these effects were accompanied by a reduction in AaMps1 protein levels in embryogenic cultures. Our work has identified the Mps1 protein in a gymnosperm species for the first time, and we have shown that inhibiting Mps1 affects cellular growth and PEM differentiation during A. angustifolia somatic embryogenesis. These data will be useful for better understanding cell cycle control during somatic embryogenesis in plants.

Mps1 (Monopolar Spindle 1) Protein Inhibition Affects Cellular Growth and Pro-Embryogenic Masses Morphology in Embryogenic Cultures of Araucaria angustifolia (Araucariaceae)

PubMed Central

Douétts-Peres, Jackellinne C.; Cruz, Marco Antônio L.; Reis, Ricardo S.; Heringer, Angelo S.; de Oliveira, Eduardo A. G.; Elbl, Paula M.; Floh, Eny I. S.; Silveira, Vanildo

2016-01-01

Somatic embryogenesis has been shown to be an efficient tool for studying processes based on cell growth and development. The fine regulation of the cell cycle is essential for proper embryo formation during the process of somatic embryogenesis. The aims of the present work were to identify and perform a structural and functional characterization of Mps1 and to analyze the effects of the inhibition of this protein on cellular growth and pro-embryogenic mass (PEM) morphology in embryogenic cultures of A. angustifolia. A single-copy Mps1 gene named AaMps1 was retrieved from the A. angustifolia transcriptome database, and through a mass spectrometry approach, AaMps1 was identified and quantified in embryogenic cultures. The Mps1 inhibitor SP600125 (10 μM) inhibited cellular growth and changed PEMs, and these effects were accompanied by a reduction in AaMps1 protein levels in embryogenic cultures. Our work has identified the Mps1 protein in a gymnosperm species for the first time, and we have shown that inhibiting Mps1 affects cellular growth and PEM differentiation during A. angustifolia somatic embryogenesis. These data will be useful for better understanding cell cycle control during somatic embryogenesis in plants. PMID:27064899

Lipase genes in Mucor circinelloides: identification, sub-cellular location, phylogenetic analysis and expression profiling during growth and lipid accumulation.

PubMed

Zan, Xinyi; Tang, Xin; Chu, Linfang; Zhao, Lina; Chen, Haiqin; Chen, Yong Q; Chen, Wei; Song, Yuanda

2016-10-01

Lipases or triacylglycerol hydrolases are widely spread in nature and are particularly common in the microbial world. The filamentous fungus Mucor circinelloides is a potential lipase producer, as it grows well in triacylglycerol-contained culture media. So far only one lipase from M. circinelloides has been characterized, while the majority of lipases remain unknown in this fungus. In the present study, 47 potential lipase genes in M. circinelloides WJ11 and 30 potential lipase genes in M. circinelloides CBS 277.49 were identified by extensive bioinformatics analysis. An overview of these lipases is presented, including several characteristics, sub-cellular location, phylogenetic analysis and expression profiling of the lipase genes during growth and lipid accumulation. All of these proteins contained the consensus sequence for a classical lipase (GXSXG motif) and were divided into four types including α/β-hydrolase_1, α/β-hydrolase_3, class_3 and GDSL lipase (GDSL) based on gene annotations. Phylogenetic analyses revealed that class_3 family and α/β-hydrolase_3 family were the conserved lipase family in M. circinelloides. Additionally, some lipases also contained a typical acyltransferase motif of H-(X) 4-D, and these lipases may play a dual role in lipid metabolism, catalyzing both lipid hydrolysis and transacylation reactions. The differential expression of all lipase genes were confirmed by quantitative real-time PCR, and the expression profiling were analyzed to predict the possible biological roles of these lipase genes in lipid metabolism in M. circinelloides. We preliminarily hypothesized that lipases may be involved in triacylglycerol degradation, phospholipid synthesis and beta-oxidation. Moreover, the results of sub-cellular localization, the presence of signal peptide and transcriptional analyses of lipase genes indicated that four lipase in WJ11 most likely belong to extracellular lipases with a signal peptide. These findings provide a platform

Enoyl-Acyl Carrier Protein Reductase I (FabI) Is Essential for the Intracellular Growth of Listeria monocytogenes

PubMed Central

Ericson, Megan E.; Frank, Matthew W.

2016-01-01

Enoyl-acyl carrier protein reductase catalyzes the last step in each elongation cycle of type II bacterial fatty acid synthesis and is a key regulatory protein in bacterial fatty acid synthesis. Genes of the facultative intracellular pathogen Listeria monocytogenes encode two functional enoyl-acyl carrier protein isoforms based on their ability to complement the temperature-sensitive growth phenotype of Escherichia coli strain JP1111 [fabI(Ts)]. The FabI isoform was inactivated by the FabI selective inhibitor AFN-1252, but the FabK isoform was not affected by the drug, as expected. Inhibition of FabI by AFN-1252 decreased endogenous fatty acid synthesis by 80% and lowered the growth rate of L. monocytogenes in laboratory medium. Robust exogenous fatty acid incorporation was not detected in L. monocytogenes unless the pathway was partially inactivated by AFN-1252 treatment. However, supplementation with exogenous fatty acids did not restore normal growth in the presence of AFN-1252. FabI inactivation prevented the intracellular growth of L. monocytogenes, showing that neither FabK nor the incorporation of host cellular fatty acids was sufficient to support the intracellular growth of L. monocytogenes. Our results show that FabI is the primary enoyl-acyl carrier protein reductase of type II bacterial fatty acid synthesis and is essential for the intracellular growth of L. monocytogenes. PMID:27736774

Enoyl-Acyl Carrier Protein Reductase I (FabI) Is Essential for the Intracellular Growth of Listeria monocytogenes.

PubMed

Yao, Jiangwei; Ericson, Megan E; Frank, Matthew W; Rock, Charles O

2016-12-01

Enoyl-acyl carrier protein reductase catalyzes the last step in each elongation cycle of type II bacterial fatty acid synthesis and is a key regulatory protein in bacterial fatty acid synthesis. Genes of the facultative intracellular pathogen Listeria monocytogenes encode two functional enoyl-acyl carrier protein isoforms based on their ability to complement the temperature-sensitive growth phenotype of Escherichia coli strain JP1111 [fabI(Ts)]. The FabI isoform was inactivated by the FabI selective inhibitor AFN-1252, but the FabK isoform was not affected by the drug, as expected. Inhibition of FabI by AFN-1252 decreased endogenous fatty acid synthesis by 80% and lowered the growth rate of L. monocytogenes in laboratory medium. Robust exogenous fatty acid incorporation was not detected in L. monocytogenes unless the pathway was partially inactivated by AFN-1252 treatment. However, supplementation with exogenous fatty acids did not restore normal growth in the presence of AFN-1252. FabI inactivation prevented the intracellular growth of L. monocytogenes, showing that neither FabK nor the incorporation of host cellular fatty acids was sufficient to support the intracellular growth of L. monocytogenes Our results show that FabI is the primary enoyl-acyl carrier protein reductase of type II bacterial fatty acid synthesis and is essential for the intracellular growth of L. monocytogenes. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Synthesis of Very-Long-Chain Fatty Acids in the Epidermis Controls Plant Organ Growth by Restricting Cell Proliferation

PubMed Central

Nobusawa, Takashi; Okushima, Yoko; Nagata, Noriko; Kojima, Mikiko; Sakakibara, Hitoshi; Umeda, Masaaki

2013-01-01

Plant organ growth is controlled by inter-cell-layer communication, which thus determines the overall size of the organism. The epidermal layer interfaces with the environment and participates in both driving and restricting growth via inter-cell-layer communication. However, it remains unknown whether the epidermis can send signals to internal tissue to limit cell proliferation in determinate growth. Very-long-chain fatty acids (VLCFAs) are synthesized in the epidermis and used in the formation of cuticular wax. Here we found that VLCFA synthesis in the epidermis is essential for proper development of Arabidopsis thaliana. Wild-type plants treated with a VLCFA synthesis inhibitor and pasticcino mutants with defects in VLCFA synthesis exhibited overproliferation of cells in the vasculature or in the rib zone of shoot apices. The decrease of VLCFA content increased the expression of IPT3, a key determinant of cytokinin biosynthesis in the vasculature, and, indeed, elevated cytokinin levels. These phenotypes were suppressed in ipt3;5;7 triple mutants, and also by vasculature-specific expression of cytokinin oxidase, which degrades active forms of cytokinin. Our results imply that VLCFA synthesis in the epidermis is required to suppress cytokinin biosynthesis in the vasculature, thus fine-tuning cell division activity in internal tissue, and therefore that shoot growth is controlled by the interaction between the surface (epidermis) and the axis (vasculature) of the plant body. PMID:23585732

Glycosaminoglycan synthesis in the mandibular condyle during growth adaptation.

PubMed

Kantomaa, T; Pirttiniemi, P; Tuominen, M; Poikela, A

1994-01-01

Condylar growth was studied after an operation simulating functional orthodontic appliances. Twenty-five rabbits underwent a surgical operation for the induction of premature synostosis to displace the glenoid fossa posteriorly during growth. Twenty-five control rabbits underwent sham operations. At the age of 15 days, 10 experimental and 10 control animals and, at the age of 20 days, 5 experimental and 5 control animals were killed. Their mandibular condyles were organ-cultured for 3 h in the presence of radiolabelled sulphur. The condyles were used for autoradiographic purposes. Digital image analysis of autoradiograms of histological sections showed synthesis of glycosaminoglycans to have increased from the anterior to the posterior direction. This increase was more marked in experimental animals than in the condyles of control animals. Ten experimental and 10 control animals were killed at the age of 15 days, and mandibular condyles were organ-cultured for 1, 4 and 7 days. Differentiation of proliferating prechondroblasts into hypertrophied chondrocytes continued under organ culture conditions. A marked decrease in the proliferating cell layer was noticed, especially in control condyles. Hypertrophy was faster and came closer to the surface of the condyle in the anterior region of the condyle. This was most marked in the condyles of experimental animals. The results indicate that a procedure carried out on the glenoid fossa with the same effect as functional appliances increases the synthesis of extracellular matrix in the posterosuperior region of the mandibular condyle.

Modelling urban growth in the Indo-Gangetic plain using nighttime OLS data and cellular automata

NASA Astrophysics Data System (ADS)

Roy Chowdhury, P. K.; Maithani, Sandeep

2014-12-01

The present study demonstrates the applicability of the Operational Linescan System (OLS) sensor in modelling urban growth at regional level. The nighttime OLS data provides an easy, inexpensive way to map urban areas at a regional scale, requiring a very small volume of data. A cellular automata (CA) model was developed for simulating urban growth in the Indo-Gangetic plain; using OLS data derived maps as input. In the proposed CA model, urban growth was expressed in terms of causative factors like economy, topography, accessibility and urban infrastructure. The model was calibrated and validated based on OLS data of year 2003 and 2008 respectively using spatial metrics measures and subsequently the urban growth was predicted for the year 2020. The model predicted high urban growth in North Western part of the study area, in south eastern part growth would be concentrated around two cities, Kolkata and Howrah. While in the middle portion of the study area, i.e., Jharkhand, Bihar and Eastern Uttar Pradesh, urban growth has been predicted in form of clusters, mostly around the present big cities. These results will not only provide an input to urban planning but can also be utilized in hydrological and ecological modelling which require an estimate of future built up areas especially at regional level.

Selective inhibition of influenza virus protein synthesis by inhibitors of DNA function. [UV radiation

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

Minor, P.D.; Dimmock, N.J.

1977-05-15

Various known inhibitors of cellular DNA function were shown to inhibit cellular RNA synthesis and influenza (fowl plague) virus multiplication. The drugs were investigated for their effect upon the synthesis of influenza virus proteins. According to this effect they could be classified with previously studied compounds as follows: Group I (ethidium bromide, proflavine, and N-nitroquinoline-N-oxide) inhibited both viral and cellular protein synthesis; Group II (nogalomycin, daunomycin and ..cap alpha..-amanitin) inhibited viral but not cellular protein synthesis, and all viral proteins were inhibited coordinately; Group III (mithramycin, echinomycin, and actinomycin D) inhibited all viral but not cellular protein synthesis at highmore » concentrations, but at a lower critical concentration inhibited the synthesis of viral haemagglutinin, neuraminidase, and M protein preferentially; Group IV(uv irradiation and camptothecin) inhibited the synthesis of viral haemagglutinin, neuraminidase, and M protein, but not other viral proteins, even at high doses. The mode of action of these inhibitors is discussed in relation to the mechanism of the nuclear events upon which influenza virus multiplication is dependent.« less

Inferring the Growth of Massive Galaxies Using Bayesian Spectral Synthesis Modeling

NASA Astrophysics Data System (ADS)

Stillman, Coley Michael; Poremba, Megan R.; Moustakas, John

2018-01-01

The most massive galaxies in the universe are typically found at the centers of massive galaxy clusters. Studying these galaxies can provide valuable insight into the hierarchical growth of massive dark matter halos. One of the key challenges of measuring the stellar mass growth of massive galaxies is converting the measured light profiles into stellar mass. We use Prospector, a state-of-the-art Bayesian spectral synthesis modeling code, to infer the total stellar masses of a pilot sample of massive central galaxies selected from the Sloan Digital Sky Survey. We compare our stellar mass estimates to previous measurements, and present some of the quantitative diagnostics provided by Prospector.

West nile virus-induced activation of mammalian target of rapamycin complex 1 supports viral growth and viral protein expression.

PubMed

Shives, Katherine D; Beatman, Erica L; Chamanian, Mastooreh; O'Brien, Caitlin; Hobson-Peters, Jody; Beckham, J David

2014-08-01

Since its introduction in New York City, NY, in 1999, West Nile virus (WNV) has spread to all 48 contiguous states of the United States and is now the leading cause of epidemic encephalitis in North America. As a member of the family Flaviviridae, WNV is part of a group of clinically important human pathogens, including dengue virus and Japanese encephalitis virus. The members of this family of positive-sense, single-stranded RNA viruses have limited coding capacity and are therefore obligated to co-opt a significant amount of cellular factors to translate their genomes effectively. Our previous work has shown that WNV growth was independent of macroautophagy activation, but the role of the evolutionarily conserved mammalian target of rapamycin (mTOR) pathway during WNV infection was not well understood. mTOR is a serine/threonine kinase that acts as a central cellular censor of nutrient status and exercises control of vital anabolic and catabolic cellular responses such as protein synthesis and autophagy, respectively. We now show that WNV activates mTOR and cognate downstream activators of cap-dependent protein synthesis at early time points postinfection and that pharmacologic inhibition of mTOR (KU0063794) significantly reduced WNV growth. We used an inducible Raptor and Rictor knockout mouse embryonic fibroblast (MEF) system to further define the role of mTOR complexes 1 and 2 in WNV growth and viral protein synthesis. Following inducible genetic knockout of the major mTOR cofactors raptor (TOR complex 1 [TORC1]) and rictor (TORC2), we now show that TORC1 supports flavivirus protein synthesis via cap-dependent protein synthesis pathways and supports subsequent WNV growth. Since its introduction in New York City, NY, in 1999, West Nile virus (WNV) has spread to all 48 contiguous states in the United States and is now the leading cause of epidemic encephalitis in North America. Currently, the mechanism by which flaviviruses such as WNV translate their genomes in

Green synthesis of Au nanoparticles using potato extract: stability and growth mechanism

NASA Astrophysics Data System (ADS)

Castillo-López, D. N.; Pal, U.

2014-08-01

We report on the synthesis of spherical, well-dispersed colloidal gold nanoparticles of 17.5-23.5 nm average sizes in water using potato extract (PE) both as reducing and stabilizing agent. The effects of PE content and the pH value of the reaction mixture have been studied. Formation and growth dynamics of the Au nanoparticles in the colloids were studied using transmission electron microscopy and UV-Vis optical absorption spectroscopy techniques. While the reductor content and, hence, the nucleation and growth rates of the nanoparticles could be controlled by controlling the PE content in the reaction solution, the stability of the nanoparticles depended strongly on the pH of the reaction mixture. The mechanisms of Au ion reduction and stabilization of Au nanoparticles by potato starch have been discussed. The use of common natural solvent like water and biological reductor like PE in our synthesis process opens up the possibility of synthesizing Au nanoparticles in fully green (environmental friendly) way, and the Au nanoparticles produced in such way should have good biocompatibility.

Human Cortical Neural Stem Cells Expressing Insulin-Like Growth Factor-I: A Novel Cellular Therapy for Alzheimer’s Disease

PubMed Central

McGinley, Lisa M.; Sims, Erika; Lunn, J. Simon; Kashlan, Osama N.; Chen, Kevin S.; Bruno, Elizabeth S.; Pacut, Crystal M.; Hazel, Tom; Johe, Karl; Sakowski, Stacey A.

2016-01-01

Alzheimer’s disease (AD) is the most prevalent age-related neurodegenerative disorder and a leading cause of dementia. Current treatment fails to modify underlying disease pathologies and very little progress has been made to develop effective drug treatments. Cellular therapies impact disease by multiple mechanisms, providing increased efficacy compared with traditional single-target approaches. In amyotrophic lateral sclerosis, we have shown that transplanted spinal neural stem cells (NSCs) integrate into the spinal cord, form synapses with the host, improve inflammation, and reduce disease-associated pathologies. Our current goal is to develop a similar “best in class” cellular therapy for AD. Here, we characterize a novel human cortex-derived NSC line modified to express insulin-like growth factor-I (IGF-I), HK532-IGF-I. Because IGF-I promotes neurogenesis and synaptogenesis in vivo, this enhanced NSC line offers additional environmental enrichment, enhanced neuroprotection, and a multifaceted approach to treating complex AD pathologies. We show that autocrine IGF-I production does not impact the cell secretome or normal cellular functions, including proliferation, migration, or maintenance of progenitor status. However, HK532-IGF-I cells preferentially differentiate into gamma-aminobutyric acid-ergic neurons, a subtype dysregulated in AD; produce increased vascular endothelial growth factor levels; and display an increased neuroprotective capacity in vitro. We also demonstrate that HK532-IGF-I cells survive peri-hippocampal transplantation in a murine AD model and exhibit long-term persistence in targeted brain areas. In conclusion, we believe that harnessing the benefits of cellular and IGF-I therapies together will provide the optimal therapeutic benefit to patients, and our findings support further preclinical development of HK532-IGF-I cells into a disease-modifying intervention for AD. Significance There is no cure for Alzheimer’s disease (AD) and

NADE (p75NTR-associated cell death executor) suppresses cellular growth in vivo.

PubMed

Tong, Xiangjun; Xie, Dong; Roth, Wilfried; Reed, John; Koeffler, H Phillip

2003-06-01

NADE, a p75NTR (low-affinity neurotrophin receptor p75) -associated cell death executor, was initially cloned from a human ovarian granulosa cell cDNA library, as an unknown protein with the name, pHGR74. It was reported to mediate nerve growth factor-induced apoptosis. We independently isolated human NADE (pHGR74) from breast cancer cell lines. Expression of NADE in various human cancer cell lines, and human and murine tissues was examined. NADE was highly expressed in human endocrine-related organs and embryotic murine tissues. Forced expression of NADE in CHO (Chinese hamster ovary) cells and MDA-MB-231 human breast cancer cells had little effect on the growth of the cells in vitro, while it dramatically suppressed cellular growth in vivo. We used the yeast two-hybrid system to search for NADE binding protein. Dynactin was identified as a candidate. The p75NTR was not found in this assay and did not co-immunoprecipitate with human NADE. Furthermore, the cells stably transfected with NADE did not respond to NGF or TNF. Thus, human and murine NADE appear to have different functions.

Growth and biosurfactant synthesis by Nigerian hydrocarbon-degrading estuarine bacteria.

PubMed

Adebusoye, Sunday A; Amund, Olukayode O; Ilori, Matthew O; Domeih, Dupe O; Okpuzor, Joy

2008-12-01

The ability of microorganisms to degrade petroleum hydrocarbons is important for finding an environmentally-friendly method to restoring contaminated environmental matrices. Screening of hydrocarbon-utilizing and biosurfactant-producing abilities of organisms from an estuarine ecosystem in Nigeria, Africa, resulted in the isolation of five microbial strains identified as Corynebacterium sp. DDV1, Flavobacterium sp. DDV2, Micrococcus roseus DDV3, Pseudomonas aeruginosa DDV4 and Saccharomyces cerevisae DDV5. These isolates grew readily on several hydrocarbons including hexadecane, dodecane, crude oil and petroleum fractions. Axenic cultures of the organisms utilized diesel oil (1.0% v/v) with generation times that ranged significantly (t-test, P < 0.05) between 3.25 and 3.88 day, with concomitant production of biosurfactants. Kinetics of growth indicates that biosurfactant synthesis occurred predominantly during exponential growth phase, suggesting that the bioactive molecules are primary metabolites. Strains DDV1 and DDV4 were evidently the most metabolically active in terms of substrate utilization and biosurfactant synthesis compared to other strains with respective emulsification index of 63 and 78%. Preliminary biochemical characterization indicates that the biosurfactants are heteropolymers consisting of lipid, protein and carbohydrate moieties. The hydrocarbon catabolic properties coupled with biosurfactant-producing capabilities is an asset that could be exploited for cleanup of oil-contaminated matrices and also in food and cosmetic industries.

Combining cellular automata and Lattice Boltzmann method to model multiscale avascular tumor growth coupled with nutrient diffusion and immune competition.

PubMed

Alemani, Davide; Pappalardo, Francesco; Pennisi, Marzio; Motta, Santo; Brusic, Vladimir

2012-02-28

In the last decades the Lattice Boltzmann method (LB) has been successfully used to simulate a variety of processes. The LB model describes the microscopic processes occurring at the cellular level and the macroscopic processes occurring at the continuum level with a unique function, the probability distribution function. Recently, it has been tried to couple deterministic approaches with probabilistic cellular automata (probabilistic CA) methods with the aim to model temporal evolution of tumor growths and three dimensional spatial evolution, obtaining hybrid methodologies. Despite the good results attained by CA-PDE methods, there is one important issue which has not been completely solved: the intrinsic stochastic nature of the interactions at the interface between cellular (microscopic) and continuum (macroscopic) level. CA methods are able to cope with the stochastic phenomena because of their probabilistic nature, while PDE methods are fully deterministic. Even if the coupling is mathematically correct, there could be important statistical effects that could be missed by the PDE approach. For such a reason, to be able to develop and manage a model that takes into account all these three level of complexity (cellular, molecular and continuum), we believe that PDE should be replaced with a statistic and stochastic model based on the numerical discretization of the Boltzmann equation: The Lattice Boltzmann (LB) method. In this work we introduce a new hybrid method to simulate tumor growth and immune system, by applying Cellular Automata Lattice Boltzmann (CA-LB) approach. Copyright © 2011 Elsevier B.V. All rights reserved.

Modeling and predicting urban growth pattern of the Tokyo metropolitan area based on cellular automata

NASA Astrophysics Data System (ADS)

Zhao, Yaolong; Zhao, Junsan; Murayama, Yuji

2008-10-01

The period of high economic growth in Japan which began in the latter half of the 1950s led to a massive migration of population from rural regions to the Tokyo metropolitan area. This phenomenon brought about rapid urban growth and urban structure changes in this area. Purpose of this study is to establish a constrained CA (Cellular Automata) model with GIS (Geographical Information Systems) to simulate urban growth pattern in the Tokyo metropolitan area towards predicting urban form and landscape for the near future. Urban land-use is classified into multi-categories for interpreting the effect of interaction among land-use categories in the spatial process of urban growth. Driving factors of urban growth pattern, such as land condition, railway network, land-use zoning, random perturbation, and neighborhood interaction and so forth, are explored and integrated into this model. These driving factors are calibrated based on exploratory spatial data analysis (ESDA), spatial statistics, logistic regression, and "trial and error" approach. The simulation is assessed at both macro and micro classification levels in three ways: visual approach; fractal dimension; and spatial metrics. Results indicate that this model provides an effective prototype to simulate and predict urban growth pattern of the Tokyo metropolitan area.

Growth, oxygen consumption, and protein and RNA synthesis rates in the yolk sac larvae of the African catfish (Clarias gariepinus).

PubMed

Smith, Richard W; Ottema, Colin

2006-03-01

Rapidly growing African catfish yolk sac larvae were investigated during the first 22 h after hatching. Body compartment protein concentration increased fourfold yet oxygen consumption remained constant (mean=21.3 +/- 3.2 nmol O2 mg(-1) protein h(-1)), suggesting fast growth results mainly from yolk sac protein absorption. The protein synthesis rates at 1-2 and 5-6 h also equaled the highest conceivable rates of muscle protein synthesis; 11.6-11.9% and 7.4-7.9% day(-1), respectively. Therefore the corresponding energetic costs of protein synthesis were almost the theoretical minimum; 13.0 +/- 1.7-16.3 +/- 2.8 micromol O2 mg(-1) protein synthesised. Total protein synthesis expenditure (74.5-77.7 micromol O2 g(-1) protein h(-1)) was also less than other yolk sac larvae. These protein synthesis rates resulted from high RNA concentrations (113.2 +/- 3.4 microg RNA mg(-1) protein) and were also correlated with RNA translational efficiency. High translational efficiency (1 h; 1.2+/-0.1 mg protein synthesised microg(-1) RNA day(-1)) equaled high synthesis rate (36.8 +/- 5.4 microg RNA microg(-1) DNA day(-1)) and both declined over 22 h. This investigation suggests rapid growth combines growth efficiency and compensatory energy partitioning. This accommodates the ontogenetic and phylogenetic standpoints imposed by energy budget limitations.

Mechanisms of Oxygen Toxicity at the Cellular Level.

DTIC Science & Technology

1982-06-30

exposed and measured using glucose as the sole carbon source. Addition of SH containing reducing agents (cysteine, lipoic acid or dithiothreitol) before...of a Few Seconds. Biotechnology and Bioengineering 16:1645-1657 (1974). (28) Brown, O.R. Failure of Lipoic Acid to Protect Against Cellular Oxygen...respiration, and fatty acid synthesis. The interruption of fatty acid synthesis is not the result of inactivation of the fatty acid synthetase enzyme complex

Nutritional and regulatory roles of leucine in muscle growth and fat reduction.

PubMed

Duan, Yehui; Li, Fengna; Liu, Hongnan; Li, Yinghui; Liu, Yingying; Kong, Xiangfeng; Zhang, Yuzhe; Deng, Dun; Tang, Yulong; Feng, Zemeng; Wu, Guoyao; Yin, Yulong

2015-01-01

The metabolic roles for L-leucine, an essential branched-chain amino acid (BCAA), go far beyond serving exclusively as a building block for de novo protein synthesis. Growing evidence shows that leucine regulates protein and lipid metabolism in animals. Specifically, leucine activates the mammalian target of rapamycin (mTOR) signaling pathway, including the 70 kDa ribosomal protein S6 kinase 1 (S6K1) and eukaryotic initiation factor (eIF) 4E-binding protein 1 (4EBP1) to stimulate protein synthesis in skeletal muscle and adipose tissue and to promote mitochondrial biogenesis, resulting in enhanced cellular respiration and energy partitioning. Activation of cellular energy metabolism favors fatty acid oxidation to CO2 and water in adipocytes, lean tissue gain in young animals, and alleviation of muscle protein loss in aging adults, lactating mammals, and food-deprived subjects. As a functional amino acid, leucine holds great promise to enhance the growth, efficiency of food utilization, and health of animals and humans. 

Unlocking the Constraints of Cyanobacterial Productivity: Acclimations Enabling Ultrafast Growth

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

Bernstein, Hans C.; McClure, Ryan S.; Hill, Eric A.

ABSTRACT Harnessing the metabolic potential of photosynthetic microbes for next-generation biotechnology objectives requires detailed scientific understanding of the physiological constraints and regulatory controls affecting carbon partitioning between biomass, metabolite storage pools, and bioproduct synthesis. We dissected the cellular mechanisms underlying the remarkable physiological robustness of the euryhaline unicellular cyanobacteriumSynechococcussp. strain PCC 7002 (Synechococcus7002) and identify key mechanisms that allow cyanobacteria to achieve unprecedented photoautotrophic productivities (~2.5-h doubling time). Ultrafast growth ofSynechococcus7002 was supported by high rates of photosynthetic electron transfer and linked to significantly elevated transcription of precursor biosynthesis and protein translation machinery. Notably, no growth or photosynthesis inhibition signaturesmore » were observed under any of the tested experimental conditions. Finally, the ultrafast growth inSynechococcus7002 was also linked to a 300% expansion of average cell volume. We hypothesize that this cellular adaptation is required at high irradiances to support higher cell division rates and reduce deleterious effects, corresponding to high light, through increased carbon and reductant sequestration. IMPORTANCEEfficient coupling between photosynthesis and productivity is central to the development of biotechnology based on solar energy. Therefore, understanding the factors constraining maximum rates of carbon processing is necessary to identify regulatory mechanisms and devise strategies to overcome productivity constraints. Here, we interrogate the molecular mechanisms that operate at a systems level to allow cyanobacteria to achieve ultrafast growth. This was done by considering growth and photosynthetic kinetics with global transcription patterns. We have delineated putative biological principles that allow unicellular cyanobacteria to achieve ultrahigh growth rates

Differential chlorate inhibition of Chaetomium globosum germination, hyphal growth, and perithecia synthesis.

PubMed

Biles, Charles L; Wright, Desiree; Fuego, Marianni; Guinn, Angela; Cluck, Terry; Young, Jennifer; Martin, Markie; Biles, Josiah; Poudyal, Shubhra

2012-12-01

Chaetomium globosum Kunze:Fr is a dermatophytic, dematiaceous fungus that is ubiquitous in soils, grows readily on cellulolytic materials, and is commonly found on water-damaged building materials. Chlorate affects nitrogen metabolism in fungi and is used to study compatibility among anamorphic fungi by inducing nit mutants. The effect of chlorate toxicity on C. globosum was investigated by amending a modified malt extract agar (MEA), oat agar, and carboxymethyl cellulose agar (CMC) with various levels of potassium chlorate (KClO(3)). C. globosum perithecia production was almost completely inhibited (90-100 %) at low levels of KClO(3) (0.1 mM) in amended MEA. Inhibition of perithecia production was also observed on oat agar and CMC at 1 and 10 mM, respectively. However, hyphal growth in MEA was only inhibited 20 % by 0.1-100 mM KClO(3) concentrations. Hyphal growth was never completely inhibited at the highest levels tested (200 mM). Higher levels of KClO(3) were needed on gypsum board to inhibit perithecia synthesis. In additional experiments, KClO(3) did not inhibit C. globosum, Fusarium oxysporum, Aspergillus niger, Penicillum expansum, and airborne fungal spore germination. The various fungal spores were not inhibited by KClO(3) at 1-100 mM levels. These results suggest that C. globosum perithecia synthesis is more sensitive to chlorate toxicity than are hyphal growth and spore germination. This research provides basic information that furthers our understanding about perithecia formation and may help in developing control methods for fungal growth on building materials.

An integrative model links multiple inputs and signaling pathways to the onset of DNA synthesis in hepatocytes

PubMed Central

Huard, Jérémy; Mueller, Stephanie; Gilles, Ernst D; Klingmüller, Ursula; Klamt, Steffen

2012-01-01

During liver regeneration, quiescent hepatocytes re-enter the cell cycle to proliferate and compensate for lost tissue. Multiple signals including hepatocyte growth factor, epidermal growth factor, tumor necrosis factor α, interleukin-6, insulin and transforming growth factor β orchestrate these responses and are integrated during the G1 phase of the cell cycle. To investigate how these inputs influence DNA synthesis as a measure for proliferation, we established a large-scale integrated logical model connecting multiple signaling pathways and the cell cycle. We constructed our model based upon established literature knowledge, and successively improved and validated its structure using hepatocyte-specific literature as well as experimental DNA synthesis data. Model analyses showed that activation of the mitogen-activated protein kinase and phosphatidylinositol 3-kinase pathways was sufficient and necessary for triggering DNA synthesis. In addition, we identified key species in these pathways that mediate DNA replication. Our model predicted oncogenic mutations that were compared with the COSMIC database, and proposed intervention targets to block hepatocyte growth factor-induced DNA synthesis, which we validated experimentally. Our integrative approach demonstrates that, despite the complexity and size of the underlying interlaced network, logical modeling enables an integrative understanding of signaling-controlled proliferation at the cellular level, and thus can provide intervention strategies for distinct perturbation scenarios at various regulatory levels. PMID:22443451

One-pot green synthesis of doxorubicin loaded-silica nanoparticles for in vivo cancer therapy.

PubMed

Jiang, Shan; Hua, Li; Guo, Zilong; Sun, Lin

2018-09-01

The present work reveals a new and simple one-pot green method to load doxorubicin (DOX) drugs in silica nanoparticles for efficient in vivo cancer therapy. The synthesis of DOX loaded silica nanoparticles (SiNPs/DOX) is based on the efficient encapsulation of DOX in surfactant Tween 80 micelles which act as a template for the formation of silica nanoparticles. The release profile, cellular uptake behavior, cytotoxicity and antitumor effect of SiNPs/DOX nanoparticles were investigated and compared to free DOX. The silica nanoparticles improved the cellular drug delivery efficiency and exhibited high cytotoxicity, successfully achieving the inhibition of tumor growth. Notably, the tumor size and weight of SiNPs/DOX group was 2-fold and 1.7-fold smaller than that of free DOX group, and 4-fold and 2-fold smaller than that of PBS group. The one-pot green synthesis system may have the potential to be developed as a promising drug delivery system. Copyright © 2018 Elsevier B.V. All rights reserved.

Measurement of cellular copper levels in Bacillus megaterium during exponential growth and sporulation.

PubMed

Krueger, W B; Kolodziej, B J

1976-01-01

Both atomic absorption spectrophotometry (AAS) and neutron activation analysis have been utilized to determine cellular Cu levels in Bacillus megaterium ATCC 19213. Both methods were selected for their sensitivity to detection of nanogram quantities of Cu. Data from both methods demonstrated identical patterms of Cu uptake during exponenetial growth and sporulation. Late exponential phase cells contained less Cu than postexponential t2 cells while t5 cells contained amounts equivalent to exponential cells. The t11 phase-bright forespore containing cells had a higher Cu content than those of earlier time periods, and the free spores had the highest Cu content. Analysis of the culture medium by AAS corroborated these data by showing concomitant Cu uptake during exponential growth and into t2 postexponential phase of sporulation. From t2 to t4, Cu egressed from the cells followed by a secondary uptake during the maturation of phase-dark forespores into phase-bright forespores (t6--t9).

Cellular Automata

NASA Astrophysics Data System (ADS)

Gutowitz, Howard

1991-08-01

Cellular automata, dynamic systems in which space and time are discrete, are yielding interesting applications in both the physical and natural sciences. The thirty four contributions in this book cover many aspects of contemporary studies on cellular automata and include reviews, research reports, and guides to recent literature and available software. Chapters cover mathematical analysis, the structure of the space of cellular automata, learning rules with specified properties: cellular automata in biology, physics, chemistry, and computation theory; and generalizations of cellular automata in neural nets, Boolean nets, and coupled map lattices. Current work on cellular automata may be viewed as revolving around two central and closely related problems: the forward problem and the inverse problem. The forward problem concerns the description of properties of given cellular automata. Properties considered include reversibility, invariants, criticality, fractal dimension, and computational power. The role of cellular automata in computation theory is seen as a particularly exciting venue for exploring parallel computers as theoretical and practical tools in mathematical physics. The inverse problem, an area of study gaining prominence particularly in the natural sciences, involves designing rules that possess specified properties or perform specified task. A long-term goal is to develop a set of techniques that can find a rule or set of rules that can reproduce quantitative observations of a physical system. Studies of the inverse problem take up the organization and structure of the set of automata, in particular the parameterization of the space of cellular automata. Optimization and learning techniques, like the genetic algorithm and adaptive stochastic cellular automata are applied to find cellular automaton rules that model such physical phenomena as crystal growth or perform such adaptive-learning tasks as balancing an inverted pole. Howard Gutowitz is

Application of cellular mechanisms to growth and development of food producing animals.

PubMed

Chung, K Y; Johnson, B J

2008-04-01

Postnatal skeletal muscle growth is a result of hypertrophy of existing skeletal muscle fibers in food producing animals. Accumulation of additional nuclei, as a source of DNA, to the multinucleated skeletal muscle fiber aids in fiber hypertrophy during periods of rapid skeletal muscle growth. Muscle satellite cells are recognized as the source of nuclei to support muscle hypertrophy. Exogenous growth-enhancing compounds have been used to modulate growth rate and efficiency in meat animals for over a half century. In cattle, these compounds enhance efficiency of growth by preferentially stimulating skeletal muscle growth compared with adipose tissue. There are 2 main classes of compounds approved for use in cattle in the United States, anabolic steroids and beta-adrenergic agonists (beta-AA). Administration of both trenbolone acetate and estradiol-17beta, as implants, increased carcass protein accumulation 8 to 10% in yearling steers. Muscle satellite cells isolated from steers implanted with trenbolone acetate/ estradiol-17beta had a shorter lag phase in culture compared with satellite cells isolated from control steers. Collectively, these data indicate that activation, increased proliferation, and subsequent fusion of satellite cells in muscles of implanted cattle may be an important mechanism by which anabolic steroids enhance muscle hypertrophy. Oral administration of beta-AA to ruminants does not alter DNA accumulation in skeletal muscle over a typical feeding period (28 to 42 d). Enhanced muscle hypertrophy observed due to beta-AA feeding occurs by direct, receptor-mediated changes in protein synthesis and degradation rates of skeletal muscle tissue. Proper timing of anabolic steroid administration when coupled with beta-AA feeding could result in a synergistic response in skeletal muscle growth due to the effects of anabolic steroids at increasing satellite cell activity, which then can support the rapid hypertrophic changes of the muscle fiber when exposed

Fracture mechanics of cellular glass

NASA Technical Reports Server (NTRS)

Zwissler, J. G.; Adams, M. A.

1981-01-01

The fracture mechanics of cellular glasses (for the structural substrate of mirrored glass for solr concentrator reflecting panels) are discussed. Commercial and developmental cellular glasses were tested and analyzed using standard testing techniques and models developed from linear fracture mechanics. Two models describing the fracture behavior of these materials were developed. Slow crack growth behavior in cellular glass was found to be more complex than that encountered in dense glasses or ceramics. The crack velocity was found to be strongly dependent upon water vapor transport to the tip of the moving crack. The existence of a static fatigue limit was not conclusively established, however, it is speculated that slow crack growth behavior in Region 1 may be slower, by orders of magnitude, than that found in dense glasses.

Emergent Behaviors from a Cellular Automaton Model for Invasive Tumor Growth in Heterogeneous Microenvironments

PubMed Central

Jiao, Yang; Torquato, Salvatore

2011-01-01

Understanding tumor invasion and metastasis is of crucial importance for both fundamental cancer research and clinical practice. In vitro experiments have established that the invasive growth of malignant tumors is characterized by the dendritic invasive branches composed of chains of tumor cells emanating from the primary tumor mass. The preponderance of previous tumor simulations focused on non-invasive (or proliferative) growth. The formation of the invasive cell chains and their interactions with the primary tumor mass and host microenvironment are not well understood. Here, we present a novel cellular automaton (CA) model that enables one to efficiently simulate invasive tumor growth in a heterogeneous host microenvironment. By taking into account a variety of microscopic-scale tumor-host interactions, including the short-range mechanical interactions between tumor cells and tumor stroma, degradation of the extracellular matrix by the invasive cells and oxygen/nutrient gradient driven cell motions, our CA model predicts a rich spectrum of growth dynamics and emergent behaviors of invasive tumors. Besides robustly reproducing the salient features of dendritic invasive growth, such as least-resistance paths of cells and intrabranch homotype attraction, we also predict nontrivial coupling between the growth dynamics of the primary tumor mass and the invasive cells. In addition, we show that the properties of the host microenvironment can significantly affect tumor morphology and growth dynamics, emphasizing the importance of understanding the tumor-host interaction. The capability of our CA model suggests that sophisticated in silico tools could eventually be utilized in clinical situations to predict neoplastic progression and propose individualized optimal treatment strategies. PMID:22215996

Porcine Reproductive and Respiratory Syndrome Virus Nucleocapsid Protein Interacts with Nsp9 and Cellular DHX9 To Regulate Viral RNA Synthesis.

PubMed

Liu, Long; Tian, Jiao; Nan, Hao; Tian, Mengmeng; Li, Yuan; Xu, Xiaodong; Huang, Baicheng; Zhou, Enmin; Hiscox, Julian A; Chen, Hongying

2016-06-01

Porcine reproductive and respiratory syndrome virus (PRRSV) nucleocapsid (N) protein is the main component of the viral capsid to encapsulate viral RNA, and it is also a multifunctional protein involved in the regulation of host cell processes. Nonstructural protein 9 (Nsp9) is the RNA-dependent RNA polymerase that plays a critical role in viral RNA transcription and replication. In this study, we demonstrate that PRRSV N protein is bound to Nsp9 by protein-protein interaction and that the contacting surface on Nsp9 is located in the two predicted α-helixes formed by 48 residues at the C-terminal end of the protein. Mutagenesis analyses identified E646, E608, and E611 on Nsp9 and Q85 on the N protein as the pivotal residues participating in the N-Nsp9 interaction. By overexpressing the N protein binding fragment of Nsp9 in infected Marc-145 cells, the synthesis of viral RNAs, as well as the production of infectious progeny viruses, was dramatically inhibited, suggesting that Nsp9-N protein association is involved in the process of viral RNA production. In addition, we show that PRRSV N interacts with cellular RNA helicase DHX9 and redistributes the protein into the cytoplasm. Knockdown of DHX9 increased the ratio of short subgenomic mRNAs (sgmRNAs); in contrast, DHX9 overexpression benefited the synthesis of longer sgmRNAs and the viral genomic RNA (gRNA). These results imply that DHX9 is recruited by the N protein in PRRSV infection to regulate viral RNA synthesis. We postulate that N and DHX9 may act as antiattenuation factors for the continuous elongation of nascent transcript during negative-strand RNA synthesis. It is unclear whether the N protein of PRRSV is involved in regulation of the viral RNA production process. In this report, we demonstrate that the N protein of the arterivirus PRRSV participates in viral RNA replication and transcription through interacting with Nsp9 and its RdRp and recruiting cellular RNA helicase to promote the production of

Ursolic Acid Inhibits Na+/K+-ATPase Activity and Prevents TNF-α-Induced Gene Expression by Blocking Amino Acid Transport and Cellular Protein Synthesis

PubMed Central

Yokomichi, Tomonobu; Morimoto, Kyoko; Oshima, Nana; Yamada, Yuriko; Fu, Liwei; Taketani, Shigeru; Ando, Masayoshi; Kataoka, Takao

2011-01-01

Pro-inflammatory cytokines, such as tumor necrosis factor (TNF)-α, induce the expression of a wide variety of genes, including intercellular adhesion molecule-1 (ICAM-1). Ursolic acid (3β-hydroxy-urs-12-en-28-oic acid) was identified to inhibit the cell-surface ICAM-1 expression induced by pro-inflammatory cytokines in human lung carcinoma A549 cells. Ursolic acid was found to inhibit the TNF-α-induced ICAM-1 protein expression almost completely, whereas the TNF-α-induced ICAM-1 mRNA expression and NF-κB signaling pathway were decreased only partially by ursolic acid. In line with these findings, ursolic acid prevented cellular protein synthesis as well as amino acid uptake, but did not obviously affect nucleoside uptake and the subsequent DNA/RNA syntheses. This inhibitory profile of ursolic acid was similar to that of the Na+/K+-ATPase inhibitor, ouabain, but not the translation inhibitor, cycloheximide. Consistent with this notion, ursolic acid was found to inhibit the catalytic activity of Na+/K+-ATPase. Thus, our present study reveals a novel molecular mechanism in which ursolic acid inhibits Na+/K+-ATPase activity and prevents the TNF-α-induced gene expression by blocking amino acid transport and cellular protein synthesis. PMID:24970122

Cardiomyocyte cell cycle control and growth estimation in vivo--an analysis based on cardiomyocyte nuclei.

PubMed

Walsh, Stuart; Pontén, Annica; Fleischmann, Bernd K; Jovinge, Stefan

2010-06-01

Adult mammalian cardiomyocytes are traditionally viewed as being permanently withdrawn from the cell cycle. Whereas some groups have reported none, others have reported extensive mitosis in adult myocardium under steady-state conditions. Recently, a highly specific assay of 14C dating in humans has suggested a continuous generation of cardiomyocytes in the adult, albeit at a very low rate. Mice represent the most commonly used animal model for these studies, but their short lifespan makes them unsuitable for 14C studies. Herein, we investigate the cellular growth pattern for murine cardiomyocyte growth under steady-state conditions, addressed with new analytical and technical strategies, and we furthermore relate this to gene expression patterns. The observed levels of DNA synthesis in early life were associated with cardiomyocyte proliferation. Mitosis was prolonged into early life, longer than the most conservative previous estimates. DNA synthesis in neonatal life was attributable to bi-nucleation, therefore suggesting that cardiomyocytes withdraw from the cell cycle shortly after birth. No cell cycle activity was observed in adult cardiomyocytes and significant polyploidy was observed in cardiomyocyte nuclei. Gene analyses identified 32 genes whose expression was predicted to be particular to day 3-4 neonatal myocytes, compared with embryonic or adult cells. These cell cycle-associated genes are crucial to the understanding of the mechanisms of bi-nucleation and physiological cellular growth in the neonatal period.

L-Citrulline Supplementation Enhances Fetal Growth and Protein Synthesis in Rats with Intrauterine Growth Restriction.

PubMed

Bourdon, Aurélie; Parnet, Patricia; Nowak, Christel; Tran, Nhat-Thang; Winer, Norbert; Darmaun, Dominique

2016-03-01

Intrauterine growth restriction (IUGR) results from either maternal undernutrition or impaired placental blood flow, exposing offspring to increased perinatal mortality and a higher risk of metabolic syndrome and cardiovascular disease during adulthood. l-Citrulline is a precursor of l-arginine and nitric oxide (NO), which regulates placental blood flow. Moreover, l-citrulline stimulates protein synthesis in other models of undernutrition. The aim of the study was to determine whether l-citrulline supplementation would enhance fetal growth in a model of IUGR induced by maternal dietary protein restriction. Pregnant rats were fed either a control (20% protein) or a low-protein (LP; 4% protein) diet. LP dams were randomly allocated to drink tap water either as such or supplemented with l-citrulline (2 g · kg(-1) · d(-1)), an isonitrogenous amount of l-arginine, or nonessential l-amino acids (NEAAs). On day 21 of gestation, dams received a 2-h infusion of l-[1-(13)C]-valine until fetuses were extracted by cesarean delivery. Isotope enrichments were measured in free amino acids and fetal muscle, liver, and placenta protein by GC-mass spectrometry. Fetal weight was ∼29% lower in the LP group (3.82 ± 0.06 g) than in the control group (5.41 ± 0.10 g) (P < 0.001). Regardless of supplementation, fetal weight remained below that of control fetuses. Yet, compared with the LP group, l-citrulline and l-arginine equally increased fetal weight to 4.15 ± 0.08 g (P < 0.05) and 4.13 ± 0.1 g (P < 0.05 compared with LP), respectively, whereas NEAA did not (4.05 ± 0.05 g; P = 0.07). Fetal muscle protein fractional synthesis rate was 35% lower in the LP fetuses (41% ± 11%/d) than in the control (61% ± 13%/d) fetuses (P < 0.001) and was normalized by l-citrulline (56% ± 4%/d; P < 0.05 compared with LP, NS compared with control) and not by other supplements. Urinary nitrite and nitrate excretion was lower in the LP group (6.4 ± 0.8 μmol/d) than in the control group (17.9 �

Growth and Decay in Life-Like Cellular Automata

NASA Astrophysics Data System (ADS)

Eppstein, David

Since the study of life began, many have asked: is it unique in the universe, or are there other interesting forms of life elsewhere? Before we can answer that question, we should ask others: What makes life special? If we happen across another system with life-like behavior, how would we be able to recognize it? We are speaking, of course, of the mathematical systems of cellular automata, of the fascinating patterns that have been discovered and engineered in Conway's Game of Life, and of the possible existence of other cellular automaton rules with equally complex behavior to that of Life.

Cellular-dendritic transition in directionally solidified binary alloys

NASA Technical Reports Server (NTRS)

Tewari, S. N.; Laxmanan, V.

1987-01-01

The microstructural development of binary alloys during directional solidification is studied. Cellular growth data for the Al-Cu and Pb-Sn binary alloy systems are analyzed in order evaluate the criteria of Kurz and Fisher (1981) and Trivedi (1984) for cellular-dendritic transition. It is observed that the experimental growth values do not correlate with the Kurz and Fisher or Trivedi data.

Catch-up Growth: Cellular and Molecular Mechanisms

PubMed Central

Finkielstain, GP; Lui, JC; Baron, J

2012-01-01

In mammals, after a period of growth inhibition, body growth often does not just return to a normal rate but actually exceeds the normal rate, resulting in catch-up growth. Recent evidence suggests that catch-up growth occurs because growth-inhibiting conditions delay progression of the physiological mechanisms that normally cause body growth to slow and cease with age. As a result, following the period of growth inhibition, tissues retain a greater proliferative capacity than normal, and therefore grow more rapidly than normal for age. There is evidence that this mechanism contributes both to catch-up growth in terms of body length, which involves proliferation in the growth plate, and to catch-up growth in terms of organ mass, which involves proliferation in multiple non-skeletal tissues. PMID:23428687

Galacturonomannan and Golgi-derived membrane linked to growth and shaping of biogenic calcite

NASA Technical Reports Server (NTRS)

Marsh, M. E.; Ridall, A. L.; Azadi, P.; Duke, P. J.

2002-01-01

The coccolithophores are valuable models for the design and synthesis of composite materials, because the cellular machinery controlling the nucleation, growth, and patterning of their calcitic scales (coccoliths) can be examined genetically. The coccoliths are formed within the Golgi complex and are the major CaCO(3) component in limestone sediments-particularly those of the Cretaceous period. In this study, we describe mutants lacking a sulfated galacturonomannan and show that this polysaccharide in conjunction with the Golgi-derived membrane is directly linked to the growth and shaping of coccolith calcite but not to the initial orientated nucleation of the mineral phase.

Growth and cellular ion content of a salt-sensitive symbiotic system Azolla pinnata-Anabaena azollae under NaCl stress.

PubMed

Rai, Vandna; Sharma, Naveen Kumar; Rai, Ashwani K

2006-09-01

Salinity, at a concentration of 10 mM NaCl affected the growth of Azolla pinnata-Anabaena azollae association and became lethal at 40 mM. Plants exposed up to 30 mM NaCl exhibited longer roots than the control, especially during the beginning of incubation. Average root number in plants exposed to 10 and 20 mM NaCl remained almost the same as in control. A further rise in NaCl concentration to 30 mM reduced the root number, and roots shed off at 40 mM NaCl. Presence of NaCl in the nutrient solution increased the cellular Na+ of the intact association exhibiting differential accumulation by individual partners, while it reduced the cellular Ca2+ level. However, cellular K+ content did not show significant change. Cellular Na+ based on fresh weight of respective individual partners (host tissues and cyanobiont) remained higher in the host tissues than the cyanobiont, while reverse was true for K+ and Ca2+ contents. The contribution of A. azollae in the total cellular ion content of the association was a little because of meagre contribution of the cyanobiont mass (19-21%). High salt sensitivity of Azolla-Anabaena complex is due to an inability of the association to maintain low Na+ and high Ca2+ cellular level.

Cellular Fatty Acid Metabolism and Cancer

PubMed Central

Currie, Erin; Schulze, Almut; Zechner, Rudolf; Walther, Tobias C.; Farese, Robert V.

2013-01-01

Cancer cells commonly have characteristic changes in metabolism. Cellular proliferation, a common feature of all cancers, requires fatty acids for synthesis of membranes and signaling molecules. Here, we provide a view of cancer cell metabolism from a lipid perspective, and we summarize evidence that limiting fatty acid availability can control cancer cell proliferation. PMID:23791484

Growth mechanisms of MgO nanocrystals via a sol-gel synthesis using different complexing agents

PubMed Central

2014-01-01

In the preparation of nanostructured materials, it is important to optimize synthesis parameters in order to obtain the desired material. This work investigates the role of complexing agents, oxalic acid and tartaric acid, in the production of MgO nanocrystals. Results from simultaneous thermogravimetric analysis (STA) show that the two different synthesis routes yield precursors with different thermal profiles. It is found that the thermal profiles of the precursors can reveal the effects of crystal growth during thermal annealing. X-ray diffraction confirms that the final products are pure, single phase and of cubic shape. It is also found that complexing agents can affect the rate of crystal growth. The structures of the oxalic acid and tartaric acid as well as the complexation sites play very important roles in the formation of the nanocrystals. The complexing agents influence the rate of growth which affects the final crystallite size of the materials. Surprisingly, it is also found that oxalic acid and tartaric acid act as surfactants inhibiting crystal growth even at a high temperature of 950°C and a long annealing time of 36 h. The crystallite formation routes are proposed to be via linear and branched polymer networks due to the different structures of the complexing agents. PMID:24650322

A cellular automata model for avascular solid tumor growth under the effect of therapy

NASA Astrophysics Data System (ADS)

Reis, E. A.; Santos, L. B. L.; Pinho, S. T. R.

2009-04-01

Tumor growth has long been a target of investigation within the context of mathematical and computer modeling. The objective of this study is to propose and analyze a two-dimensional stochastic cellular automata model to describe avascular solid tumor growth, taking into account both the competition between cancer cells and normal cells for nutrients and/or space and a time-dependent proliferation of cancer cells. Gompertzian growth, characteristic of some tumors, is described and some of the features of the time-spatial pattern of solid tumors, such as compact morphology with irregular borders, are captured. The parameter space is studied in order to analyze the occurrence of necrosis and the response to therapy. Our findings suggest that transitions exist between necrotic and non-necrotic phases (no-therapy cases), and between the states of cure and non-cure (therapy cases). To analyze cure, the control and order parameters are, respectively, the highest probability of cancer cell proliferation and the probability of the therapeutic effect on cancer cells. With respect to patterns, it is possible to observe the inner necrotic core and the effect of the therapy destroying the tumor from its outer borders inwards.

Spatiotemporal chaos near the onset of cellular growth during thin-film solidification of a binary alloy

NASA Technical Reports Server (NTRS)

Lee, J. T. C.; Tsiveriotis, K.; Brown, R. A.

1992-01-01

Thin-film solidification experiments with a succinonitrile-acetone alloy are used to observe the long time-scale dynamics of cellular crystal growth at growth rates only slightly above the critical value VC = Vc(lambda sub c) for the onset of morphological instability. Under these conditions only very small amplitude cells are observed with wavelengths near the value predicted by linear stability theory lambda = lambda sub c. At long times, microstructures with wavelengths significantly finer than lambda suc c form by nucleation at defects across the interface. These interfaces do not have a unique microstructure, but seem to exhibit spatiotemporal chaos on a long time scale caused by the continual birth and death of cells by tip splitting and cell annihilation in grooves.

Cellular differentiation in response to nutrient availability: The repressor of meiosis, Rme1p, positively regulates invasive growth in Saccharomyces cerevisiae.

PubMed Central

van Dyk, Dewald; Hansson, Guy; Pretorius, Isak S; Bauer, Florian F

2003-01-01

In the yeast Saccharomyces cerevisiae, the transition from a nutrient-rich to a nutrient-limited growth medium typically leads to the implementation of a cellular adaptation program that results in invasive growth and/or the formation of pseudohyphae. Complete depletion of essential nutrients, on the other hand, leads either to entry into a nonbudding, metabolically quiescent state referred to as G0 in haploid strains or to meiosis and sporulation in diploids. Entry into meiosis is repressed by the transcriptional regulator Rme1p, a zinc-finger-containing DNA-binding protein. In this article, we show that Rme1p positively regulates invasive growth and starch metabolism in both haploid and diploid strains by directly modifying the transcription of the FLO11 (also known as MUC1) and STA2 genes, which encode a cell wall-associated protein essential for invasive growth and a starch-degrading glucoamylase, respectively. Genetic evidence suggests that Rme1p functions independently of identified signaling modules that regulate invasive growth and of other transcription factors that regulate FLO11 and that the activation of FLO11 is dependent on the presence of a promoter sequence that shows significant homology to identified Rme1p response elements (RREs). The data suggest that Rme1p functions as a central switch between different cellular differentiation pathways. PMID:14668363

Unusual effects of penicillin G and chloramphenicol on the growth of Moraxella osloensis.

PubMed

DeLeys, R J; Juni, E

1977-11-01

Growth of exponential-phase liquid cultures of Moraxella osloensis was inhibited by 0.5 U of penicillin G per ml. For this organism, low concentrations of penicillin acted primarily in a bacteriostatic rather than in a bactericidal manner. At higher concentrations of penicillin some killing did take place, but the rate of killing was rather slow and appeared to be independent of penicillin concentration. Microscopic observation of cells from penicillin-treated cultures showed little or no cellular swelling or lysis. The total cell count did not decrease significantly during 6 h of incubation in 5,000 U of penicillin per ml. The rates of respiration, nucleic acid synthesis, and protein synthesis were not affected by the presence of penicillin. Attempts to counteract the bactericidal action of high concentrations of penicillin with growth inhibitory concentrations of chloramphenicol were unsuccessful, since chloramphenicol itself was more bactericidal than penicillin for M. osloensis.

Unusual Effects of Penicillin G and Chloramphenicol on the Growth of Moraxella osloensis

PubMed Central

DeLeys, Robert J.; Juni, Elliot

1977-01-01

Growth of exponential-phase liquid cultures of Moraxella osloensis was inhibited by 0.5 U of penicillin G per ml. For this organism, low concentrations of penicillin acted primarily in a bacteriostatic rather than in a bactericidal manner. At higher concentrations of penicillin some killing did take place, but the rate of killing was rather slow and appeared to be independent of penicillin concentration. Microscopic observation of cells from penicillin-treated cultures showed little or no cellular swelling or lysis. The total cell count did not decrease significantly during 6 h of incubation in 5,000 U of penicillin per ml. The rates of respiration, nucleic acid synthesis, and protein synthesis were not affected by the presence of penicillin. Attempts to counteract the bactericidal action of high concentrations of penicillin with growth inhibitory concentrations of chloramphenicol were unsuccessful, since chloramphenicol itself was more bactericidal than penicillin for M. osloensis. PMID:335964

Cyanobacteria in CELSS: Growth strategies for nutritional variation and nitrogen cycling

NASA Technical Reports Server (NTRS)

Fry, I. V.; Packer, L.

1990-01-01

Cyanobacteria (blue-green algae) are versatile organisms which are capable of adjusting their cellular levels of carbohydrate, protein, and lipid in response to changes in the environment. Under stress conditions there is an imbalance between nitrogen metabolism and carbohydrate/lipid synthesis. The lesion in nitrogen assimilation is at the level of transport: the stress condition diverts energy from the active accumulation of nitrate to the extrusion of salt, and probably inhibits a cold-labile ATP'ace in the case of cold shock. Both situations affect the bioenergetic status of the cell such that the nitrogenous precursors for protein synthesis are depleted. Dispite the inhibition of protein synthesis and growth, photosynthetic reductant generation is relatively unaffected. The high O2 reductant would normally lead to photo-oxidative damage of cellular components; however, the organism copes by channeling the 'excess' reductant into carbon storage products. The increase in glycogen (28 to 35 percent dry weight increase) and the elongation of lipid fatty acid side chains (2 to 5 percent dry weight increase) at the expense of protein synthesis (25 to 34 percent dry weight decrease) results in carbohydrate, lipid and protein ratios that are closer to those required in the human diet. In addition, the selection of nitrogen fixing mutants which excrete ammonium ions present an opportunity to tailor these micro-organisms to meet the specific need for a sub-system to reverse potential loss of fixed nitrogen material.

Alternative Ways to Think about Cellular Internal Ribosome Entry*

PubMed Central

Gilbert, Wendy V.

2010-01-01

Internal ribosome entry sites (IRESs) are specialized mRNA elements that allow recruitment of eukaryotic ribosomes to naturally uncapped mRNAs or to capped mRNAs under conditions in which cap-dependent translation is inhibited. Putative cellular IRESs have been proposed to play crucial roles in stress responses, development, apoptosis, cell cycle control, and neuronal function. However, most of the evidence for cellular IRES activity rests on bicistronic reporter assays, the reliability of which has been questioned. Here, the mechanisms underlying cap-independent translation of cellular mRNAs and the contributions of such translation to cellular protein synthesis are discussed. I suggest that the division of cellular mRNAs into mutually exclusive categories of “cap-dependent” and “IRES-dependent” should be reconsidered and that the implications of cellular IRES activity need to be incorporated into our models of cap-dependent initiation. PMID:20576611

Cellular oxido-reductive proteins of Chlamydomonas reinhardtii control the biosynthesis of silver nanoparticles

PubMed Central

2011-01-01

Background Elucidation of molecular mechanism of silver nanoparticles (SNPs) biosynthesis is important to control its size, shape and monodispersity. The evaluation of molecular mechanism of biosynthesis of SNPs is of prime importance for the commercialization and methodology development for controlling the shape and size (uniform distribution) of SNPs. The unicellular algae Chlamydomonas reinhardtii was exploited as a model system to elucidate the role of cellular proteins in SNPs biosynthesis. Results The C. reinhardtii cell free extract (in vitro) and in vivo cells mediated synthesis of silver nanoparticles reveals SNPs of size range 5 ± 1 to 15 ± 2 nm and 5 ± 1 to 35 ± 5 nm respectively. In vivo biosynthesized SNPs were localized in the peripheral cytoplasm and at one side of flagella root, the site of pathway of ATP transport and its synthesis related enzymes. This provides an evidence for the involvement of oxidoreductive proteins in biosynthesis and stabilization of SNPs. Alteration in size distribution and decrease of synthesis rate of SNPs in protein-depleted fractions confirmed the involvement of cellular proteins in SNPs biosynthesis. Spectroscopic and SDS-PAGE analysis indicate the association of various proteins on C. reinhardtii mediated in vivo and in vitro biosynthesized SNPs. We have identified various cellular proteins associated with biosynthesized (in vivo and in vitro) SNPs by using MALDI-MS-MS, like ATP synthase, superoxide dismutase, carbonic anhydrase, ferredoxin-NADP+ reductase, histone etc. However, these proteins were not associated on the incubation of pre-synthesized silver nanoparticles in vitro. Conclusion Present study provides the indication of involvement of molecular machinery and various cellular proteins in the biosynthesis of silver nanoparticles. In this report, the study is mainly focused towards understanding the role of diverse cellular protein in the synthesis and capping of silver nanoparticles using C. reinhardtii as

Nicotine-induced retardation of chondrogenesis through down-regulation of IGF-1 signaling pathway to inhibit matrix synthesis of growth plate chondrocytes in fetal rats

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

Deng, Yu; Cao, Hong; Cu, Fenglong

Previous studies have confirmed that maternal tobacco smoking causes intrauterine growth retardation (IUGR) and skeletal growth retardation. Among a multitude of chemicals associated with cigarette smoking, nicotine is one of the leading candidates for causing low birth weights. However, the possible mechanism of delayed chondrogenesis by prenatal nicotine exposure remains unclear. We investigated the effects of nicotine on fetal growth plate chondrocytes in vivo and in vitro. Rats were given 2.0 mg/kg·d of nicotine subcutaneously from gestational days 11 to 20. Prenatal nicotine exposure increased the levels of fetal blood corticosterone and resulted in fetal skeletal growth retardation. Moreover, nicotinemore » exposure induced the inhibition of matrix synthesis and down-regulation of insulin-like growth factor 1 (IGF-1) signaling in fetal growth plates. The effects of nicotine on growth plates were studied in vitro by exposing fetal growth plate chondrocytes to 0, 1, 10, or 100 μM of nicotine for 10 days. Nicotine inhibited matrix synthesis and down-regulated IGF-1 signaling in chondrocytes in a concentration-dependent manner. These results suggest that prenatal nicotine exposure induces delayed chondrogenesis and that the mechanism may involve the down-regulation of IGF-1 signaling and the inhibition of matrix synthesis by growth plate chondrocytes. The present study aids in the characterization of delayed chondrogenesis caused by prenatal nicotine exposure, which might suggest a candidate mechanism for intrauterine origins of osteoporosis and osteoarthritis. - Highlights: ► Prenatal nicotine-exposure could induce delayed chondrogenesis in fetal rats. ► Nicotine inhibits matrix synthesis of fetal growth plate chondrocytes. ► Nicotine inhibits IGF-1 signaling pathway in fetal growth plate chondrocytes.« less

Viral Activation of Cellular Metabolism

PubMed Central

Sanchez, Erica L.; Lagunoff, Michael

2015-01-01

To ensure optimal environments for their replication and spread, viruses have evolved to alter many host cell pathways. In the last decade, metabolomic studies have shown that eukaryotic viruses induce large-scale alterations in host cellular metabolism. Most viruses examined to date induce aerobic glycolysis also known as the Warburg effect. Many viruses tested also induce fatty acid synthesis as well as glutaminolysis. These modifications of carbon source utilization by infected cells can increase available energy for virus replication and virion production, provide specific cellular substrates for virus particles and create viral replication niches while increasing infected cell survival. Each virus species also likely requires unique metabolic changes for successful spread and recent research has identified additional virus-specific metabolic changes induced by many virus species. A better understanding of the metabolic alterations required for each virus may lead to novel therapeutic approaches through targeted inhibition of specific cellular metabolic pathways. PMID:25812764

Cell Proliferation, Reactive Oxygen and Cellular Glutathione

PubMed Central

Day, Regina M.; Suzuki, Yuichiro J.

2005-01-01

A variety of cellular activities, including metabolism, growth, and death, are regulated and modulated by the redox status of the environment. A biphasic effect has been demonstrated on cellular proliferation with reactive oxygen species (ROS)—especially hydrogen peroxide and superoxide—in which low levels (usually submicromolar concentrations) induce growth but higher concentrations (usually >10–30 micromolar) induce apoptosis or necrosis. This phenomenon has been demonstrated for primary, immortalized and transformed cell types. However, the mechanism of the proliferative response to low levels of ROS is not well understood. Much of the work examining the signal transduction by ROS, including H2O2, has been performed using doses in the lethal range. Although use of higher ROS doses have allowed the identification of important signal transduction pathways, these pathways may be activated by cells only in association with ROS-induced apoptosis and necrosis, and may not utilize the same pathways activated by lower doses of ROS associated with increased cell growth. Recent data has shown that low levels of exogenous H2O2 up-regulate intracellular glutathione and activate the DNA binding activity toward antioxidant response element. The modulation of the cellular redox environment, through the regulation of cellular glutathione levels, may be a part of the hormetic effect shown by ROS on cell growth. PMID:18648617

The controlled growth of perovskite thin films: Opportunities, challenges, and synthesis

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

Schlom, D.G.; Theis, C.D.; Hawley, M.E.

1997-10-01

The broad spectrum of electronic and optical properties exhibited by perovskites offers tremendous opportunities for microelectronic devices, especially when a combination of properties in a single device is desired. Molecular beam epitaxy (MBE) has achieved unparalleled control in the integration of semiconductors at the monolayer-level; its use for the integration of perovskites with similar nanoscale customization appears promising. Composition control and oxidation are often significant challenges to the growth of perovskites by MBE, but we show that these can be met through the use of purified ozone as an oxidant and real-time atomic absorption composition control. The opportunities, challenges, andmore » synthesis of oxide heterostructures by reactive MBE are described, with examples taken from the growth of oxide superconductors and oxide ferroelectrics.« less

Effect of 2',3'-dideoxythymidine-5'-triphosphate on HeLa cell in vitro DNA synthesis: evidence that DNA polymerase alpha is the only polymerase required for cellular DNA replication.

PubMed Central

Waqar, M A; Evans, M J; Huberman, J A

1978-01-01

We have studied the effects of the nucleotide analogue, 2',3'-dideoxythymidine-5'-triphosphate (ddTTP) on replicative DNA synthesis in HeLa cell lysates. As previously demonstrated (1), such lysates carry out extensive DNA synthesis in vitro, at rates and in a fashion similar to in vivo DNA replication. We report here that all aspects of DNA synthesis in such lysates (total dNTP incorporation, elongation of continuous nascent strands, and the initiation, elongation, and joining of Okazaki pieces) are only slightly inhibited by concentrations of ddTTP as high as 100-500 micrometer when the dTTP concentration is maintained at 10 micrometer. This finding is consistent with the report by Edenberg, Anderson, and DePamphilis (2) that all aspects of replicative in vitro simian virus 40 DNA synthesis are also resistant to ddTTP. We also find, in agreement with Edenberg, Anderson, and DePamphilis (2), that DNA synthesis catalyzed by DNA polymerases beta or gamma is easily inhibited by ddTTP, while synthesis catalyzed by DNA polymerase alpha is very resistant. These observations suggest that DNA polymerase alpha may be the only DNA polymerase required for all aspects of cellular DNA synthesis. PMID:673840

L-Arginine promotes protein synthesis and cell growth in brown adipocyte precursor cells via the mTOR signal pathway.

PubMed

Ma, Xi; Han, Meng; Li, Defa; Hu, Shengdi; Gilbreath, Kyler R; Bazer, Fuller W; Wu, Guoyao

2017-05-01

L-Arginine has been reported to enhance brown adipose tissue developments in fetal lambs of obese ewes, but the underlying mechanism is unknown. The present study tested the hypothesis that L-arginine stimulates growth and development of brown adipocyte precursor cells (BAPCs) through activation of mammalian target of rapamycin cell signaling. BAPCs isolated from fetal lambs at day 90 of gestation were incubated   for 6 h in arginine-free DMEM, and then cultured in DMEM with concentrations of 50, 100, 200, 500 or 1000 μmol L-arginine/L for 24-96 h. Cell proliferation, protein turnover, the mammalian target of rapamycin (mTOR) signaling pathway and pre-adipocyte differentiation markers were determined. L-arginine treatment enhanced (P < 0.05) BAPC growth and protein synthesis, while inhibiting proteolysis in a dose-dependent manner. Compared with 50 and 100 μmol/L (the concentrations of arginine in the maternal plasma of obese ewes), 200 μmol L-arginine/L (the concentrations of arginine in the maternal plasma of obese ewes receiving arginine supplementation) increased (P < 0.05) the abundances of phosphorylated mTOR, P70 S6K and 4EBP1, as well as the abundances of PGC1α, UCP1, BMP7 and PRDM16. These novel findings indicate that increasing extra-cellular arginine concentration from 50 to 200 µmol/L activates mTOR cell signaling in BAPCs and enhances their growth and development in a dose-dependent manner. Our results provide a mechanism for arginine supplementation to enhance the development of brown adipose tissue in fetal lambs.

Variable-Internal-Stores models of microbial growth and metabolism with dynamic allocation of cellular resources.

PubMed

Nev, Olga A; van den Berg, Hugo A

2017-01-01

Variable-Internal-Stores models of microbial metabolism and growth have proven to be invaluable in accounting for changes in cellular composition as microbial cells adapt to varying conditions of nutrient availability. Here, such a model is extended with explicit allocation of molecular building blocks among various types of catalytic machinery. Such an extension allows a reconstruction of the regulatory rules employed by the cell as it adapts its physiology to changing environmental conditions. Moreover, the extension proposed here creates a link between classic models of microbial growth and analyses based on detailed transcriptomics and proteomics data sets. We ascertain the compatibility between the extended Variable-Internal-Stores model and the classic models, demonstrate its behaviour by means of simulations, and provide a detailed treatment of the uniqueness and the stability of its equilibrium point as a function of the availabilities of the various nutrients.

Multiscale Systems Analysis of Root Growth and Development: Modeling Beyond the Network and Cellular Scales

PubMed Central

Band, Leah R.; Fozard, John A.; Godin, Christophe; Jensen, Oliver E.; Pridmore, Tony; Bennett, Malcolm J.; King, John R.

2012-01-01

Over recent decades, we have gained detailed knowledge of many processes involved in root growth and development. However, with this knowledge come increasing complexity and an increasing need for mechanistic modeling to understand how those individual processes interact. One major challenge is in relating genotypes to phenotypes, requiring us to move beyond the network and cellular scales, to use multiscale modeling to predict emergent dynamics at the tissue and organ levels. In this review, we highlight recent developments in multiscale modeling, illustrating how these are generating new mechanistic insights into the regulation of root growth and development. We consider how these models are motivating new biological data analysis and explore directions for future research. This modeling progress will be crucial as we move from a qualitative to an increasingly quantitative understanding of root biology, generating predictive tools that accelerate the development of improved crop varieties. PMID:23110897

Prostaglandin E₂ regulates cellular migration via induction of vascular endothelial growth factor receptor-1 in HCA-7 human colon cancer cells.

PubMed

Fujino, Hiromichi; Toyomura, Kaori; Chen, Xiao-bo; Regan, John W; Murayama, Toshihiko

2011-02-01

An important event in the development of tumors is angiogenesis, or the formation of new blood vessels. Angiogenesis is also known to be involved in tumor cell metastasis and is dependent upon the activity of the vascular endothelial growth factor (VEGF) signaling pathway. Studies of mice in which the EP3 prostanoid receptors have been genetically deleted have shown a role for these receptors in cancer growth and angiogenesis. In the present study, human colon cancer HCA-7 cells were used as a model system to understand the potential role of EP3 receptors in tumor cell migration. We now show that stimulation of HCA-7 cells with PGE₂ enhanced the up-regulation of VEGF receptor-1 (VEGFR-1) expression by a mechanism involving EP3 receptor-mediated activation of phosphatidylinositol 3-kinase and the extracellular signal-regulated kinases. Moreover, the PGE₂ stimulated increase in VEGFR-1 expression was accompanied by an increase in the cellular migration of HCA-7 cells. Given the known involvement of VEGFR-1 in cellular migration, our results suggest that EP3 receptors may contribute to tumor cell metastasis by increasing cellular migration through the up-regulation of VEGFR-1 signaling. Copyright © 2010 Elsevier Inc. All rights reserved.

Synthesis of dopamine in E. coli using plasmid-based expression system and its marked effect on host growth profiles.

PubMed

Das, Arunangshu; Verma, Anita; Mukherjee, Krishna J

2017-09-14

L-Dopa and dopamine are important pathway intermediates toward the synthesis of catecholamine such as epinephrine and norepinephrine from amino acid L-tyrosine. Dopamine, secreted from dopaminergic nerve cells, serves as an important neurotransmitter. We report the synthesis of dopamine by extending the aromatic amino acid pathway of Escherichia coli DH5α by the expression of 4-hydroxyphenylacetate-3-hydrolase (HpaBC) from E. coli and an engineered dopa decarboxylase (DDC) from pig kidney cell. The activity of HpaBC and DDC require 200 µM iron supplementation and 50 µM vitamin B6, respectively as additives to the growth media. The maximum concentration of L-dopa and dopamine obtained from the broth was around 26 and 27 mg/L after 24 hr of separate shake flask studies. We observed that in the presence of dopamine synthesized in vivo host growth was remarkably enhanced. These observations lead us to an interesting finding about the role of these catecholamines on bacterial growth. It is clear that synthesis of dopamine in vivo actually promotes growth much efficiently as compared to when dopamine is added to the system from outside. From HPLC and GC-MS data it was further observed that L-dopa was stable within the observable time of experiments whereas dopamine actually was subjected to degradation via oxidation and host consumption.

Entrainment of the Mammalian Cell Cycle by the Circadian Clock: Modeling Two Coupled Cellular Rhythms

PubMed Central

Gérard, Claude; Goldbeter, Albert

2012-01-01

The cell division cycle and the circadian clock represent two major cellular rhythms. These two periodic processes are coupled in multiple ways, given that several molecular components of the cell cycle network are controlled in a circadian manner. For example, in the network of cyclin-dependent kinases (Cdks) that governs progression along the successive phases of the cell cycle, the synthesis of the kinase Wee1, which inhibits the G2/M transition, is enhanced by the complex CLOCK-BMAL1 that plays a central role in the circadian clock network. Another component of the latter network, REV-ERBα, inhibits the synthesis of the Cdk inhibitor p21. Moreover, the synthesis of the oncogene c-Myc, which promotes G1 cyclin synthesis, is repressed by CLOCK-BMAL1. Using detailed computational models for the two networks we investigate the conditions in which the mammalian cell cycle can be entrained by the circadian clock. We show that the cell cycle can be brought to oscillate at a period of 24 h or 48 h when its autonomous period prior to coupling is in an appropriate range. The model indicates that the combination of multiple modes of coupling does not necessarily facilitate entrainment of the cell cycle by the circadian clock. Entrainment can also occur as a result of circadian variations in the level of a growth factor controlling entry into G1. Outside the range of entrainment, the coupling to the circadian clock may lead to disconnected oscillations in the cell cycle and the circadian system, or to complex oscillatory dynamics of the cell cycle in the form of endoreplication, complex periodic oscillations or chaos. The model predicts that the transition from entrainment to 24 h or 48 h might occur when the strength of coupling to the circadian clock or the level of growth factor decrease below critical values. PMID:22693436

Sulfur-Doped Zinc Oxide (ZnO) Nanostars: Synthesis and Simulation of Growth Mechanism

DTIC Science & Technology

2011-10-01

Zinc Oxide ( ZnO ) Nanostars: Synthesis and Simulation of Growth Mechanism Jinhyun Cho1, Qiubao Lin2,3, Sungwoo...characterization, and ab initio simulations of star-shaped hexagonal zinc oxide ( ZnO ) nanowires. The ZnO nanostructures were synthesized by a low...Introduction Zinc oxide ( ZnO ) is a wide bandgap (3.37 eV), Ⅱ–Ⅵ semiconductor of great interest for optoelectronic applications [1–3]. Its

[A Cellular Automata Model for a Community Comprising Two Plant Species of Different Growth Forms].

PubMed

Frolov, P V; Zubkova, E V; Komarov, A S

2015-01-01

A cellular automata computer model for the interactions between two plant species of different growth forms--the lime hairgrass Deschampsia caespitosa (L.) P. Beauv., a sod cereal, and the moneywort Lysimachia nummularia L., a ground creeping perennial herb--is considered. Computer experiments on the self-maintenance of the populations of each species against the background of a gradual increase in the share of randomly eliminated individuals, coexistence of the populations of two species, and the effect of the phytogenous field have been conducted. As has been shown, all the studied factors determine the number of individuals and self-sustainability of the simulated populations by the degree of their impact. The limits of action have been determined for individual factors; within these limits, the specific features in plant reproduction and dispersal provide sustainable coexistence of the simulated populations. It has been demonstrated that the constructed model allows for studying the long-term developmental dynamics of the plants belonging to the selected growth forms.

Divergent synthesis and identification of the cellular targets of deoxyelephantopins

NASA Astrophysics Data System (ADS)

Lagoutte, Roman; Serba, Christelle; Abegg, Daniel; Hoch, Dominic G.; Adibekian, Alexander; Winssinger, Nicolas

2016-08-01

Herbal extracts containing sesquiterpene lactones have been extensively used in traditional medicine and are known to be rich in α,β-unsaturated functionalities that can covalently engage target proteins. Here we report synthetic methodologies to access analogues of deoxyelephantopin, a sesquiterpene lactone with anticancer properties. Using alkyne-tagged cellular probes and quantitative proteomics analysis, we identified several cellular targets of deoxyelephantopin. We further demonstrate that deoxyelephantopin antagonizes PPARγ activity in situ via covalent engagement of a cysteine residue in the zinc-finger motif of this nuclear receptor.

Altered Lipid Synthesis by Lack of Yeast Pah1 Phosphatidate Phosphatase Reduces Chronological Life Span*

PubMed Central

Park, Yeonhee; Han, Gil-Soo; Mileykovskaya, Eugenia; Garrett, Teresa A.; Carman, George M.

2015-01-01

In Saccharomyces cerevisiae, Pah1 phosphatidate phosphatase, which catalyzes the dephosphorylation of phosphatidate to yield diacylglycerol, plays a crucial role in the synthesis of the storage lipid triacylglycerol. This evolutionarily conserved enzyme also plays a negative regulatory role in controlling de novo membrane phospholipid synthesis through its consumption of phosphatidate. We found that the pah1Δ mutant was defective in the utilization of non-fermentable carbon sources but not in oxidative phosphorylation; the mutant did not exhibit major changes in oxygen consumption rate, mitochondrial membrane potential, F1F0-ATP synthase activity, or gross mitochondrial morphology. The pah1Δ mutant contained an almost normal complement of major mitochondrial phospholipids with some alterations in molecular species. Although oxidative phosphorylation was not compromised in the pah1Δ mutant, the cellular levels of ATP in quiescent cells were reduced by 2-fold, inversely correlating with a 4-fold increase in membrane phospholipids. In addition, the quiescent pah1Δ mutant cells had 3-fold higher levels of mitochondrial superoxide and cellular lipid hydroperoxides, had reduced activities of superoxide dismutase 2 and catalase, and were hypersensitive to hydrogen peroxide. Consequently, the pah1Δ mutant had a shortened chronological life span. In addition, the loss of Tsa1 thioredoxin peroxidase caused a synthetic growth defect with the pah1Δ mutation. The shortened chronological life span of the pah1Δ mutant along with its growth defect on non-fermentable carbon sources and hypersensitivity to hydrogen peroxide was suppressed by the loss of Dgk1 diacylglycerol kinase, indicating that the underpinning of pah1Δ mutant defects was the excess synthesis of membrane phospholipids. PMID:26338708

Inferring the Limit Behavior of Some Elementary Cellular Automata

NASA Astrophysics Data System (ADS)

Ruivo, Eurico L. P.; de Oliveira, Pedro P. B.

Cellular automata locally define dynamical systems, discrete in space, time and in the state variables, capable of displaying arbitrarily complex global emergent behavior. One core question in the study of cellular automata refers to their limit behavior, that is, to the global dynamical features in an infinite time evolution. Previous works have shown that for finite time evolutions, the dynamics of one-dimensional cellular automata can be described by regular languages and, therefore, by finite automata. Such studies have shown the existence of growth patterns in the evolution of such finite automata for some elementary cellular automata rules and also inferred the limit behavior of such rules based upon the growth patterns; however, the results on the limit behavior were obtained manually, by direct inspection of the structures that arise during the time evolution. Here we present the formalization of an automatic method to compute such structures. Based on this, the rules of the elementary cellular automata space were classified according to the existence of a growth pattern in their finite automata. Also, we present a method to infer the limit graph of some elementary cellular automata rules, derived from the analysis of the regular expressions that describe their behavior in finite time. Finally, we analyze some attractors of two rules for which we could not compute the whole limit set.

Physiological-phased kinetic characteristics of microalgae Chlorella vulgaris growth and lipid synthesis considering synergistic effects of light, carbon and nutrients.

PubMed

Liao, Qiang; Chang, Hai-Xing; Fu, Qian; Huang, Yun; Xia, Ao; Zhu, Xun; Zhong, Nianbing

2018-02-01

To comprehensively understand kinetic characteristics of microalgae growth and lipid synthesis in different phases, a phase-feeding strategy was proposed to simultaneously regulate light, carbon and nutrients in adaption, growth and stationary phases of microalgae cultivation. Physiological-phased kinetic characteristics of microalgae Chlorella vulgaris growth and lipid synthesis under synergistic effects of light, carbon and nutrients were investigated, and supply-demand relationships of electrons and energy between light and dark reactions of photosynthesis process were discussed. Finally, the optimized cultivation strategy for microalgae in various phases were obtained, under which the lipid productivity was significantly improved from 130.11 mg/L/d to 163.42 mg/L/d. The study provided some important guidance for the large-scale production of biofuels from microalgae. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cellular La protein shields nonsegmented negative-strand RNA viral leader RNA from RIG-I and enhances virus growth by diverse mechanisms.

PubMed

Bitko, Vira; Musiyenko, Alla; Bayfield, Mark A; Maraia, Richard J; Barik, Sailen

2008-08-01

The La antigen (SS-B) associates with a wide variety of cellular and viral RNAs to affect gene expression in multiple systems. We show that La is the major cellular protein found to be associated with the abundant 44-nucleotide viral leader RNA (leRNA) early after infection with respiratory syncytial virus (RSV), a nonsegmented negative-strand RNA virus. Consistent with this, La redistributes from the nucleus to the cytoplasm in RSV-infected cells. Upon RNA interference knockdown of La, leRNA is redirected to associate with the RNA-binding protein RIG-I, a known activator of interferon (IFN) gene expression, and this is accompanied by the early induction of IFN mRNA. These results suggest that La shields leRNA from RIG-I, abrogating the early viral activation of type I IFN. We mapped the leRNA binding function to RNA recognition motif 1 of La and showed that while wild-type La greatly enhanced RSV growth, a La mutant defective in RSV leRNA binding also did not support RSV growth. Comparative studies of RSV and Sendai virus and the use of IFN-negative Vero cells indicated that La supports the growth of nonsegmented negative-strand RNA viruses by both IFN suppression and a potentially novel IFN-independent mechanism.

The effects of glutathione depletion on thermotolerance and heat stress protein synthesis.

PubMed Central

Russo, A.; Mitchell, J. B.; McPherson, S.

1984-01-01

The effects of cellular glutathione depletion by buthionine sulfoximine on the development of thermotolerance and synthesis of heat stress protein was studied. Cellular glutathione levels were found to increase rapidly following an acute heat treatment of either 12 min at 45.5 degrees C or 1 h at 43 degrees C and remain elevated for prolonged periods. Glutathione depletion and prevention of glutathione synthesis by buthionine sulfoximine resulted in inhibition of the development of thermotolerance and a decrease in total protein as well as specific heat stress proteins. While the degree of inhibition of thermotolerance was similar for both glutathione depletion protocols, inhibition in heat stress protein synthesis was greater when glutathione was depleted to low levels prior to heating. The possible role of glutathione and the cellular redox state to thermotolerance and synthesis of heat stress protein is discussed. Images Figure 2 PMID:6733022

Host Pah1p phosphatidate phosphatase limits viral replication by regulating phospholipid synthesis

PubMed Central

Zhang, Zhenlu; He, Guijuan; Catanzaro, Nicholas; Wu, Zujian; Xie, Lianhui

2018-01-01

Replication of positive-strand RNA viruses [(+)RNA viruses] takes place in membrane-bound viral replication complexes (VRCs). Formation of VRCs requires virus-mediated manipulation of cellular lipid synthesis. Here, we report significantly enhanced brome mosaic virus (BMV) replication and much improved cell growth in yeast cells lacking PAH1 (pah1Δ), the sole yeast ortholog of human LIPIN genes. PAH1 encodes Pah1p (phosphatidic acid phosphohydrolase), which converts phosphatidate (PA) to diacylglycerol that is subsequently used for the synthesis of the storage lipid triacylglycerol. Inactivation of Pah1p leads to altered lipid composition, including high levels of PA, total phospholipids, ergosterol ester, and free fatty acids, as well as expansion of the nuclear membrane. In pah1Δ cells, BMV replication protein 1a and double-stranded RNA localized to the extended nuclear membrane, there was a significant increase in the number of VRCs formed, and BMV genomic replication increased by 2-fold compared to wild-type cells. In another yeast mutant that lacks both PAH1 and DGK1 (encodes diacylglycerol kinase converting diacylglycerol to PA), which has a normal nuclear membrane but maintains similar lipid compositional changes as in pah1Δ cells, BMV replicated as efficiently as in pah1Δ cells, suggesting that the altered lipid composition was responsible for the enhanced BMV replication. We further showed that increased levels of total phospholipids play an important role because the enhanced BMV replication required active synthesis of phosphatidylcholine, the major membrane phospholipid. Moreover, overexpression of a phosphatidylcholine synthesis gene (CHO2) promoted BMV replication. Conversely, overexpression of PAH1 or plant PAH1 orthologs inhibited BMV replication in yeast or Nicotiana benthamiana plants. Competing with its host for limited resources, BMV inhibited host growth, which was markedly alleviated in pah1Δ cells. Our work suggests that Pah1p promotes

Novel vascular endothelial growth factor blocker improves cellular viability and reduces hypobaric hypoxia-induced vascular leakage and oedema in rat brain.

PubMed

Saraswat, Deepika; Nehra, Sarita; Chaudhary, Kamal; CVS, Siva Prasad

2015-05-01

Vascular endothelial growth factor (VEGF) is an important cerebral angiogenic and permeability factor under hypoxia. There is a need to find effective molecules that may ameliorate hypoxia-induced cerebral oedema. In silico identification of novel candidate molecules that block VEGF-A site were identified and validated with a Ramachandran plot. The active site residues of VEGF-A were detected by Pocketfinder, CASTp, and DogSiteScorer. Based on in silico data, three VEGF-A blocker (VAB) candidate molecules (VAB1, VAB2, and VAB3) were checked for improvement in cellular viability and regulation of VEGF levels in N2a cells under hypoxia (0.5% O2 ). Additionally, the best candidate molecule's efficacy was assessed in male Sprague-Dawley rats for its ameliorative effect on cerebral oedema and vascular leakage under hypobaric hypoxia 7260 m. All experimental results were compared with the commercially available VEGF blocker sunitinib. Vascular endothelial growth factor-A blocker 1 was found most effective in increasing cellular viability and maintaining normal VEGF levels under hypoxia (0.5% oxygen) in N2a cells. Vascular endothelial growth factor-A blocker 1 effectively restored VEGF levels, decreased cerebral oedema, and reduced vascular leakage under hypobaric hypoxia when compared to sunitinib-treated rats. Vascular endothelial growth factor-A blocker 1 may be a promising candidate molecule for ameliorating hypobaric hypoxia-induced vasogenic oedema by regulating VEGF levels. © 2015 Wiley Publishing Asia Pty Ltd.

INVITED REVIEW: Inhibitors of myostatin as methods of enhancing muscle growth and development.

PubMed

Chen, P R; Lee, K

2016-08-01

With the increasing demand for affordable, high-quality meat, livestock and poultry producers must continually find ways to maximize muscle growth in their animals without compromising palatability of the meat products. Muscle mass relies on myoblast proliferation during prenatal or prehatch stages and fiber hypertrophy through protein synthesis and nuclei donation by satellite cells after birth or hatch. Therefore, understanding the cellular and molecular mechanisms of myogenesis and muscle development is of great interest. Myostatin is a well-known negative regulator of muscle growth and development that inhibits proliferation and differentiation in myogenic cells as well as protein synthesis in existing muscle fibers. In this review, various inhibitors of myostatin activity or signaling are examined that may be used in animal agriculture for enhancing muscle growth. Myostatin inhibitors are relevant as potential therapies for muscle-wasting diseases and muscle weakness in humans and animals. Currently, there are no commercial myostatin inhibitors for agriculture or biomedical purposes because the safest and most effective option has yet to be identified. Further investigation of myostatin inhibitors and administration strategies may revolutionize animal production and the medical field.

Biomimetic hybrid porous scaffolds immobilized with platelet derived growth factor-BB promote cellularization and vascularization in tissue engineering.

PubMed

Murali, Ragothaman; Ponrasu, Thangavel; Cheirmadurai, Kalirajan; Thanikaivelan, Palanisamy

2016-02-01

Development of hybrid scaffolds with synergistic combination of growth factor is a promising approach to promote early in vivo wound repair and tissue regeneration. Here, we show the rapid wound healing in Wistar albino rats using biomimetic collagen-poly(dialdehyde) guar gum based hybrid porous scaffolds covalently immobilized with platelet derived growth factor-BB. The immobilized platelet derived growth factor in the hybrid scaffolds not only enhance the total protein, collagen, hexosamine, and uronic acid contents in the granulation tissue but also provide stronger tissues. The wound closure analysis reveal that the complete epithelialization period is 15.4 ± 0.9 days for collagen-poly(dialdehyde) guar gum-platelet derived growth factor hybrid scaffolds, whereas it is significantly higher for control, collagen, collagen- poly(dialdehyde) guar gum and povidine-iodine treated groups. Further, the histological evaluation shows that the immobilized platelet derived growth factor in the hybrid scaffolds induced a more robust cellular and vascular response in the implanted site. Hence, we demonstrate that the collagen-poly(dialdehyde) guar gum hybrid scaffolds loaded with platelet derived growth factor stimulates chemotactic effects in the implanted site to promote rapid tissue regeneration and wound repair without the assistance of antibacterial agents. © 2015 Wiley Periodicals, Inc.

Selective coexpression of VEGF receptor 2 in EGFRvIII-positive glioblastoma cells prevents cellular senescence and contributes to their aggressive nature.

PubMed

Jones, Karra A; Gilder, Andrew S; Lam, Michael S; Du, Na; Banki, Michael A; Merati, Aran; Pizzo, Donald P; VandenBerg, Scott R; Gonias, Steven L

2016-05-01

In glioblastoma (GBM), the gene for epidermal growth factor receptor (EGFR) is frequently amplified. EGFR mutations also are common, including a truncation mutation that yields a constitutively active variant called EGFR variant (v)III. EGFRvIII-positive GBM progresses rapidly; however, the reason for this is not clear because the activity of EGFRvIII is attenuated compared with EGF-ligated wild-type EGFR. We hypothesized that EGFRvIII-expressing GBM cells selectively express other oncogenic receptors that support tumor progression. Mining of The Cancer Genome Atlas prompted us to test whether GBM cells in culture, which express EGFRvIII, selectively express vascular endothelial growth factor receptor (VEGFR)2. We also studied human GBM propagated as xenografts. We then applied multiple approaches to test the effects of VEGFR2 on GBM cell growth, apoptosis, and cellular senescence. In human GBM, EGFR overexpression and EGFRvIII positivity were associated with increased VEGFR2 expression. In GBM cells in culture, EGFRvIII-initiated cell signaling increased expression of VEGFR2, which prevented cellular senescence and promoted cell cycle progression. The VEGFR-selective tyrosine kinase inhibitor cediranib decreased tumor DNA synthesis, increased staining for senescence-associated β-galactosidase, reduced retinoblastoma phosphorylation, and increased p27(Kip1), all markers of cellular senescence. Similar results were obtained when VEGFR2 was silenced. VEGFR2 expression by GBM cells supports cell cycle progression and prevents cellular senescence. Coexpression of VEGFR2 by GBM cells in which EGFR signaling is activated may contribute to the aggressive nature of these cells. © The Author(s) 2015. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Hormonal regulation of growth and life span of bullfrog tadpole tail epidermal cells cultured in vitro.

PubMed

Nishikawa, A; Yoshizato, K

1986-02-01

Epidermal cells were dissociated from tails of the bullfrog tadpole, Rana catesbeiana, and cultured to investigate their response to steroid and thyroid hormones. Charcoal-treated serum (CTS) was used in the growth medium when cells were to be grown in the absence of steroid and thyroid hormones. The cells could be maintained for 2 weeks with a small increase in cell number in medium that contained CTS (CTS medium). Addition of cortisol to CTS medium increased both cellular attachment to the culture dishes and the proliferation of the attached cells with an optimum concentration of 5 X 10(-7) M. The cells remained viable and attached for at least a week. Cortisol stimulated the rate of protein synthesis 1.8-fold but did not alter the rate of DNA synthesis. The cells did not proliferate in the medium containing triiodothyronine (T3) and detached themselves from the dish within 5 days, which occurred in a dose-dependent manner with a maximum effect at 10(-8) M. It drastically decreased the rate of DNA synthesis but did not influence the rate of protein synthesis. These responses of cells to cortisol and T3 may reflect growth and death of tail epidermal cells in vivo at metamorphosis.

Growth hormone is a cellular senescence target in pituitary and nonpituitary cells

PubMed Central

Chesnokova, Vera; Zhou, Cuiqi; Ben-Shlomo, Anat; Zonis, Svetlana; Tani, Yuji; Ren, Song-Guang; Melmed, Shlomo

2013-01-01

Premature proliferative arrest in benign or early-stage tumors induced by oncoproteins, chromosomal instability, or DNA damage is associated with p53/p21 activation, culminating in either senescence or apoptosis, depending on cell context. Growth hormone (GH) elicits direct peripheral metabolic actions as well as growth effects mediated by insulin-like growth factor 1 (IGF1). Locally produced peripheral tissue GH, in contrast to circulating pituitary-derived endocrine GH, has been proposed to be both proapoptotic and prooncogenic. Pituitary adenomas expressing and secreting GH are invariably benign and exhibit DNA damage and a senescent phenotype. We therefore tested effects of nutlin-induced p53-mediated senescence in rat and human pituitary cells. We show that DNA damage senescence induced by nutlin triggers the p53/p21 senescent pathway, with subsequent marked induction of intracellular pituitary GH in vitro. In contrast, GH is not induced in cells devoid of p53. Furthermore we show that p53 binds specific GH promoter motifs and enhances GH transcription and secretion in senescent pituitary adenoma cells and also in nonpituitary (human breast and colon) cells. In vivo, treatment with nutlin results in up-regulation of both p53 and GH in the pituitary gland, as well as increased GH expression in nonpituitary tissues (lung and liver). Intracrine GH acts in pituitary cells as an apoptosis switch for p53-mediated senescence, likely protecting the pituitary adenoma from progression to malignancy. Unlike in the pituitary, in nonpituitary cells GH exerts antiapoptotic properties. Thus, the results show that GH is a direct p53 transcriptional target and fulfills criteria as a p53 target gene. Induced GH is a readily measurable cell marker for p53-mediated cellular senescence. PMID:23940366

The Molecular and Cellular Events That Take Place during Craniofacial Distraction Osteogenesis

PubMed Central

Rachmiel, Adi

2014-01-01

Summary: Gradual bone lengthening using distraction osteogenesis principles is the gold standard for the treatment of hypoplastic facial bones. However, the long treatment time is a major disadvantage of the lengthening procedures. The aim of this study is to review the current literature and summarize the cellular and molecular events occurring during membranous craniofacial distraction osteogenesis. Mechanical stimulation by distraction induces biological responses of skeletal regeneration that is accomplished by a cascade of biological processes that may include differentiation of pluripotential tissue, angiogenesis, osteogenesis, mineralization, and remodeling. There are complex interactions between bone-forming osteoblasts and other cells present within the bone microenvironment, particularly vascular endothelial cells that may be pivotal members of a complex interactive communication network in bone. Studies have implicated number of cytokines that are intimately involved in the regulation of bone synthesis and turnover. The gene regulation of numerous cytokines (transforming growth factor-β, bone morphogenetic proteins, insulin-like growth factor-1, and fibroblast growth factor-2) and extracellular matrix proteins (osteonectin, osteopontin) during distraction osteogenesis has been best characterized and discussed. Understanding the biomolecular mechanisms that mediate membranous distraction osteogenesis may guide the development of targeted strategies designed to improve distraction osteogenesis and accelerate bone regeneration that may lead to shorten the treatment duration. PMID:25289295

Epstein-Barr virus growth/latency III program alters cellular microRNA expression

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

Cameron, Jennifer E.; Tulane Cancer Center, Tulane University Health Sciences Center, 1430 Tulane Avenue, SL79, New Orleans, LA 70112; Fewell, Claire

The Epstein-Barr virus (EBV) is associated with lymphoid and epithelial cancers. Initial EBV infection alters lymphocyte gene expression, inducing cellular proliferation and differentiation as the virus transitions through consecutive latency transcription programs. Cellular microRNAs (miRNAs) are important regulators of signaling pathways and are implicated in carcinogenesis. The extent to which EBV exploits cellular miRNAs is unknown. Using micro-array analysis and quantitative PCR, we demonstrate differential expression of cellular miRNAs in type III versus type I EBV latency including elevated expression of miR-21, miR-23a, miR-24, miR-27a, miR-34a, miR-146a and b, and miR-155. In contrast, miR-28 expression was found to be lowermore » in type III latency. The EBV-mediated regulation of cellular miRNAs may contribute to EBV signaling and associated cancers.« less

Interplay of bistable kinetics of gene expression during cellular growth

NASA Astrophysics Data System (ADS)

Zhdanov, Vladimir P.

2009-02-01

In cells, the bistable kinetics of gene expression can be observed on the level of (i) one gene with positive feedback between protein and mRNA production, (ii) two genes with negative mutual feedback between protein and mRNA production, or (iii) in more complex cases. We analyse the interplay of two genes of type (ii) governed by a gene of type (i) during cellular growth. In particular, using kinetic Monte Carlo simulations, we show that in the case where gene 1, operating in the bistable regime, regulates mutually inhibiting genes 2 and 3, also operating in the bistable regime, the latter genes may eventually be trapped either to the state with high transcriptional activity of gene 2 and low activity of gene 3 or to the state with high transcriptional activity of gene 3 and low activity of gene 2. The probability to get to one of these states depends on the values of the model parameters. If genes 2 and 3 are kinetically equivalent, the probability is equal to 0.5. Thus, our model illustrates how different intracellular states can be chosen at random with predetermined probabilities. This type of kinetics of gene expression may be behind complex processes occurring in cells, e.g., behind the choice of the fate by stem cells.

Numerical simulation of biofilm growth in flow channels using a cellular automaton approach coupled with a macro flow computation.

PubMed

Yamamoto, Takehiro; Ueda, Shuya

2013-01-01

Biofilm is a slime-like complex aggregate of microorganisms and their products, extracellular polymer substances, that grows on a solid surface. The growth phenomenon of biofilm is relevant to the corrosion and clogging of water pipes, the chemical processes in a bioreactor, and bioremediation. In these phenomena, the behavior of the biofilm under flow has an important role. Therefore, controlling the biofilm behavior in each process is important. To provide a computational tool for analyzing biofilm growth, the present study proposes a computational model for the simulation of biofilm growth in flows. This model accounts for the growth, decay, detachment and adhesion of biofilms. The proposed model couples the computation of the surrounding fluid flow, using the finite volume method, with the simulation of biofilm growth, using the cellular automaton approach, a relatively low-computational-cost method. Furthermore, a stochastic approach for considering the adhesion process is proposed. Numerical simulations for the biofilm growth on a planar wall and that in an L-shaped rectangular channel were carried out. A variety of biofilm structures were observed depending on the strength of the flow. Moreover, the importance of the detachment and adhesion processes was confirmed.

Acidosis induces reprogramming of cellular metabolism to mitigate oxidative stress

PubMed Central

2013-01-01

Background A variety of oncogenic and environmental factors alter tumor metabolism to serve the distinct cellular biosynthetic and bioenergetic needs present during oncogenesis. Extracellular acidosis is a common microenvironmental stress in solid tumors, but little is known about its metabolic influence, particularly when present in the absence of hypoxia. In order to characterize the extent of tumor cell metabolic adaptations to acidosis, we employed stable isotope tracers to examine how acidosis impacts glucose, glutamine, and palmitate metabolism in breast cancer cells exposed to extracellular acidosis. Results Acidosis increased both glutaminolysis and fatty acid β-oxidation, which contribute metabolic intermediates to drive the tricarboxylic acid cycle (TCA cycle) and ATP generation. Acidosis also led to a decoupling of glutaminolysis and novel glutathione (GSH) synthesis by repressing GCLC/GCLM expression. We further found that acidosis redirects glucose away from lactate production and towards the oxidative branch of the pentose phosphate pathway (PPP). These changes all serve to increase nicotinamide adenine dinucleotide phosphate (NADPH) production and counter the increase in reactive oxygen species (ROS) present under acidosis. The reduced novel GSH synthesis under acidosis may explain the increased demand for NADPH to recycle existing pools of GSH. Interestingly, acidosis also disconnected novel ribose synthesis from the oxidative PPP, seemingly to reroute PPP metabolites to the TCA cycle. Finally, we found that acidosis activates p53, which contributes to both the enhanced PPP and increased glutaminolysis, at least in part, through the induction of G6PD and GLS2 genes. Conclusions Acidosis alters the cellular metabolism of several major metabolites, which induces a significant degree of metabolic inflexibility. Cells exposed to acidosis largely rely upon mitochondrial metabolism for energy generation to the extent that metabolic intermediates are

Modeling the mechanics of cancer: effect of changes in cellular and extra-cellular mechanical properties.

PubMed

Katira, Parag; Bonnecaze, Roger T; Zaman, Muhammad H

2013-01-01

Malignant transformation, though primarily driven by genetic mutations in cells, is also accompanied by specific changes in cellular and extra-cellular mechanical properties such as stiffness and adhesivity. As the transformed cells grow into tumors, they interact with their surroundings via physical contacts and the application of forces. These forces can lead to changes in the mechanical regulation of cell fate based on the mechanical properties of the cells and their surrounding environment. A comprehensive understanding of cancer progression requires the study of how specific changes in mechanical properties influences collective cell behavior during tumor growth and metastasis. Here we review some key results from computational models describing the effect of changes in cellular and extra-cellular mechanical properties and identify mechanistic pathways for cancer progression that can be targeted for the prediction, treatment, and prevention of cancer.

The physics of cellular synthesis, growth and division

NASA Technical Reports Server (NTRS)

Pollard, E. C.

1974-01-01

Three areas of research in NASA'S University Program are described. Primitive terrestrial living cells were studied as a guide to the kind of cells to look for in extraterrestrial life. Experiments in zero gravity conditions are described with emphasis upon effects on small organisms. The effects of ionizing radiation on cells are studied so that it will be possible to predict dosages which can be tolerated by humans with no permanent damage.

Niemann-pick type C1 (NPC1) overexpression alters cellular cholesterol homeostasis.

PubMed

Millard, E E; Srivastava, K; Traub, L M; Schaffer, J E; Ory, D S

2000-12-08

The Niemann-Pick type C1 (NPC1) protein is a key participant in intracellular trafficking of low density lipoprotein cholesterol, but its role in regulation of sterol homeostasis is not well understood. To characterize further the function of NPC1, we generated stable Chinese hamster ovary (CHO) cell lines overexpressing the human NPC1 protein (CHO/NPC1). NPC1 overexpression increases the rate of trafficking of low density lipoprotein cholesterol to the endoplasmic reticulum and the rate of delivery of endosomal cholesterol to the plasma membrane (PM). CHO/NPC1 cells exhibit a 1.5-fold increase in total cellular cholesterol and up to a 2.9-fold increase in PM cholesterol. This increase in PM cholesterol is closely paralleled by a 3-fold increase in de novo cholesterol synthesis. Inhibition of cholesterol synthesis results in marked redistribution of PM cholesterol to intracellular sites, suggesting an unsuspected role for NPC1 in internalization of PM cholesterol. Despite elevated total cellular cholesterol, CHO/NPC1 cells exhibit increased cholesterol synthesis, which may be attributable to both resistance to oxysterol suppression of sterol-regulated gene expression and to reduced endoplasmic reticulum cholesterol levels under basal conditions. Taken together, these studies provide important new insights into the role of NPC1 in the determination of the levels and distribution of cellular cholesterol.

The similia principle: results obtained in a cellular model system.

PubMed

Wiegant, Fred; Van Wijk, Roeland

2010-01-01

This paper describes the results of a research program focused on the beneficial effect of low dose stress conditions that were applied according to the similia principle to cells previously disturbed by more severe stress conditions. In first instance, we discuss criteria for research on the similia principle at the cellular level. Then, the homologous ('isopathic') approach is reviewed, in which the initial (high dose) stress used to disturb cellular physiology and the subsequent (low dose) stress are identical. Beneficial effects of low dose stress are described in terms of increased cellular survival capacity and at the molecular level as an increase in the synthesis of heat shock proteins (hsps). Both phenomena reflect a stimulation of the endogenous cellular self-recovery capacity. Low dose stress conditions applied in a homologous approach stimulate the synthesis of hsps and enhance survival in comparison with stressed cells that were incubated in the absence of low dose stress conditions. Thirdly, the specificity of the low dose stress condition is described where the initial (high dose) stress is different in nature from the subsequently applied (low dose) stress; the heterologous or 'heteropathic' approach. The results support the similia principle at the cellular level and add to understanding of how low dose stress conditions influence the regulatory processes underlying self-recovery. In addition, the phenomenon of 'symptom aggravation' which is also observed at the cellular level, is discussed in the context of self-recovery. Finally, the difference in efficiency between the homologous and the heterologous approach is discussed; a perspective is indicated for further research; and the relationship between studies on the similia principle and the recently introduced concept of 'postconditioning hormesis' is emphasized. Copyright 2009 The Faculty of Homeopathy. Published by Elsevier Ltd. All rights reserved.

Protein metabolism in marine animals: the underlying mechanism of growth.

PubMed

Fraser, Keiron P P; Rogers, Alex D

2007-01-01

Growth is a fundamental process within all marine organisms. In soft tissues, growth is primarily achieved by the synthesis and retention of proteins as protein growth. The protein pool (all the protein within the organism) is highly dynamic, with proteins constantly entering the pool via protein synthesis or being removed from the pool via protein degradation. Any net change in the size of the protein pool, positive or negative, is termed protein growth. The three inter-related processes of protein synthesis, degradation and growth are together termed protein metabolism. Measurement of protein metabolism is vital in helping us understand how biotic and abiotic factors affect growth and growth efficiency in marine animals. Recently, the developing fields of transcriptomics and proteomics have started to offer us a means of greatly increasing our knowledge of the underlying molecular control of protein metabolism. Transcriptomics may also allow us to detect subtle changes in gene expression associated with protein synthesis and degradation, which cannot be detected using classical methods. A large literature exists on protein metabolism in animals; however, this chapter concentrates on what we know of marine ectotherms; data from non-marine ectotherms and endotherms are only discussed when the data are of particular relevance. We first consider the techniques available to measure protein metabolism, their problems and what validation is required. Protein metabolism in marine organisms is highly sensitive to a wide variety of factors, including temperature, pollution, seasonality, nutrition, developmental stage, genetics, sexual maturation and moulting. We examine how these abiotic and biotic factors affect protein metabolism at the level of whole-animal (adult and larval), tissue and cellular protein metabolism. Available gene expression data, which help us understand the underlying control of protein metabolism, are also discussed. As protein metabolism appears to

DC Plasma Synthesis of Vertically Aligned Carbon Nanofibers for Biointerfacing

NASA Astrophysics Data System (ADS)

Pearce, Ryan Christopher

Vertically aligned carbon nanofibers (VACNFs) are a class of materials whose nanoscale dimensions and physical properties makes them uniquely suitable as functional elements in many applications for biodetection and biointerfacing on a cellular level. Control of VACNF synthesis by catalytic plasma enhanced chemical vapor deposition (PECVD) presents many challenges in integration into devices and structures designed for biointerfacing, such as transparent or flexible substrates. This dissertation addresses ways to overcome many of these issues in addition to deepening the fundamental understanding of nano-synthesis in catalytic PECVD. First, a survey of the field of VACNF synthesis and biointerfacing is presented, identifying the present challenges and greatest experimental applications. It is followed by experimental observations that elucidate the underlying mechanism to fiber alignment during synthesis, a critical step for deterministic control of fiber growth. Using a grid of electrodes patterned by photolithography on an insulating substrate, it was found that the alignment of the fibers is controlled by the anisotropic etching provided by ions during dc-PECVD synthesis. The VACNFs that have been utilized for many cellular interfacing experiments have unique mechanical and fluorescent properties due to a SiNx coating. The mechanism for SiNx deposition to VACNF sidewalls during synthesis is explored in addition to a detailed study of the optical properties of the coating. To explain the optical properties of this coating it is proposed that the source of photoluminescence for the SiNx coated VACNFs is quantum confinement effects due to the presence of silicon nanoclusters embedded in a Si3N4 matrix. These luminescent fibers have proven useful as registry markers in cell impalefection studies. To realize VACNF arrays used as an inflatable angioplasty balloon with embedded fibers to deliver drugs across the blood-brain barrier, a method for transferring fibers to

At a glance: cellular biology for engineers.

PubMed

Khoshmanesh, K; Kouzani, A Z; Nahavandi, S; Baratchi, S; Kanwar, J R

2008-10-01

Engineering contributions have played an important role in the rise and evolution of cellular biology. Engineering technologies have helped biologists to explore the living organisms at cellular and molecular levels, and have created new opportunities to tackle the unsolved biological problems. There is now a growing demand to further expand the role of engineering in cellular biology research. For an engineer to play an effective role in cellular biology, the first essential step is to understand the cells and their components. However, the stumbling block of this step is to comprehend the information given in the cellular biology literature because it best suits the readers with a biological background. This paper aims to overcome this bottleneck by describing the human cell components as micro-plants that form cells as micro-bio-factories. This concept can accelerate the engineers' comprehension of the subject. In this paper, first the structure and function of different cell components are described. In addition, the engineering attempts to mimic various cell components through numerical modelling or physical implementation are highlighted. Next, the interaction of different cell components that facilitate complicated chemical processes, such as energy generation and protein synthesis, are described. These complex interactions are translated into simple flow diagrams, generally used by engineers to represent multi-component processes.

Equiaxed and columnar dendrite growth simulation in Al-7Si- Mg ternary alloys using cellular automaton method

NASA Astrophysics Data System (ADS)

Chen, Rui; Xu, Qingyan; Liu, Baicheng

2015-06-01

In this paper, a modified cellular automaton (MCA) model allowing for the prediction of dendrite growth of Al-Si-Mg ternary alloys in two and three dimensions is presented. The growth kinetic of S/L interface is calculated based on the solute equilibrium approach. In order to describe the dendrite growth with arbitrarily crystallographic orientations, this model introduces a modified decentered octahedron algorithm for neighborhood tracking to eliminate the effect of mesh dependency on dendrite growth. The thermody namic and kinetic data needed for dendrite growth is obtained through coupling with Pandat software package in combination with thermodynamic/kinetic/equilibrium phase diagram calculation databases. The effect of interactions between various alloying elements on solute diffusion coefficient is considered in the model. This model has first been used to simulate Al-7Si (weight percent) binary dendrite growth followed by a validation using theoretical predictions. For ternary alloy, Al-7Si-0.5Mg dendrite simulation has been carried out and the effects of solute interactions on diffusion matrix as well as the differences of Si and Mg in solute distribution have been analyzed. For actual application, this model has been applied to simulate the equiaxed dendrite growth with various crystallographic orientations of Al-7Si-0.36Mg ternary alloy, and the predicted secondary dendrite arm spacing (SDAS) shows a reasonable agreement with the experimental ones. Furthermore, the columnar dendrite growth in directional solidification has also been simulated and the predicted primary dendrite arm spacing (PDAS) is in good agreement with experiments. The simulated results effectively demonstrate the abilities of the model in prediction of dendritic microstructure of Al-Si-Mg ternary alloy.

Cell-wall recycling and synthesis in Escherichia coli and Pseudomonas aeruginosa - their role in the development of resistance.

PubMed

Dhar, Supurna; Kumari, Hansi; Balasubramanian, Deepak; Mathee, Kalai

2018-01-01

The bacterial cell-wall that forms a protective layer over the inner membrane is called the murein sacculus - a tightly cross-linked peptidoglycan mesh unique to bacteria. Cell-wall synthesis and recycling are critical cellular processes essential for cell growth, elongation and division. Both de novo synthesis and recycling involve an array of enzymes across all cellular compartments, namely the outer membrane, periplasm, inner membrane and cytoplasm. Due to the exclusivity of peptidoglycan in the bacterial cell-wall, these players are the target of choice for many antibacterial agents. Our current understanding of cell-wall biochemistry and biogenesis in Gram-negative organisms stems mostly from studies of Escherichia coli. An incomplete knowledge on these processes exists for the opportunistic Gram-negative pathogen, Pseudomonas aeruginosa. In this review, cell-wall synthesis and recycling in the various cellular compartments are compared and contrasted between E. coli and P. aeruginosa. Despite the fact that there is a remarkable similarity of these processes between the two bacterial species, crucial differences alter their resistance to β-lactams, fluoroquinolones and aminoglycosides. One of the common mediators underlying resistance is the amp system whose mechanism of action is closely associated with the cell-wall recycling pathway. The activation of amp genes results in expression of AmpC β-lactamase through its cognate regulator AmpR which further regulates multi-drug resistance. In addition, other cell-wall recycling enzymes also contribute to antibiotic resistance. This comprehensive summary of the information should spawn new ideas on how to effectively target cell-wall processes to combat the growing resistance to existing antibiotics.

Skeletal-muscle growth and protein turnover.

PubMed Central

Millward, D J; Garlick, P J; Stewart, R J; Nnanyelugo, D O; Waterlow, J C

1975-01-01

Because of turnover, protein synthesis and breakdown can each be involved in the regulation of the growth of tissue protein. To investigate the regulation of skeletal-muscle-protein growth we measured rates of protein synthesis and breakdown in growing rats during development on a good diet, during development on a marginally low-protein diet and during rehabilitation on a good diet after a period of severe protein deficiency. Rates of protein synthesis were measured in vivo with a constant intravenous infusion of [14C]tyrosine. The growth rate of muscle protein was measured and the rate of breakdown calculated as breakdown rate=synthesis rate-growth rate. These measurements showed that during development on a good diet there was a fall with age in the rate of protein synthesis resulting from a fall in capacity (RNA concentration) and activity (synthesis rate per unit of RNA). There was a fall with age in the breakdown rate so that the rate was highest in the weaning rats, with a half-life of 3 days. There was a direct correlation between the fractional growth and breakdown rates. During rehabilitation on the good diet, rapid growth was also accompanied by high rates of protein breakdown. During growth on the inadequate diet protein synthesis rates were lesss than in controls, but growth occurred because of decreased rates of protein breakdown. This compression was not complete, however, since ultimate muscle size was only one-half that of controls. It is suggested that increased rates of protein breakdown are a necessary accompaniment to muscle growth and may result from the way in which myofibrils proliferate. PMID:1180916

A mitochondria-selective near-infrared-emitting fluorescent dye for cellular imaging studies.

PubMed

Choi, Peter; Noguchi, Katsuya; Ishiyama, Munetaka; Denny, William A; Jose, Jiney

2018-05-03

This communication details the synthesis, evaluation of photophysical properties, and cellular imaging studies of cyanine chromophore based fluorescent dye 1 as a selective imaging agent for mitochondria. Copyright © 2018 Elsevier Ltd. All rights reserved.

Composite alginate gels for tunable cellular microenvironment mechanics

NASA Astrophysics Data System (ADS)

Khavari, Adele; Nydén, Magnus; Weitz, David A.; Ehrlicher, Allen J.

2016-08-01

The mechanics of the cellular microenvironment can be as critical as biochemistry in directing cell behavior. Many commonly utilized materials derived from extra-cellular-matrix create excellent scaffolds for cell growth, however, evaluating the relative mechanical and biochemical effects independently in 3D environments has been difficult in frequently used biopolymer matrices. Here we present 3D sodium alginate hydrogel microenvironments over a physiological range of stiffness (E = 1.85 to 5.29 kPa), with and without RGD binding sites or collagen fibers. We use confocal microscopy to measure the growth of multi-cellular aggregates (MCAs), of increasing metastatic potential in different elastic moduli of hydrogels, with and without binding factors. We find that the hydrogel stiffness regulates the growth and morphology of these cell clusters; MCAs grow larger and faster in the more rigid environments similar to cancerous breast tissue (E = 4-12 kPa) as compared to healthy tissue (E = 0.4-2 kpa). Adding binding factors from collagen and RGD peptides increases growth rates, and change maximum MCA sizes. These findings demonstrate the utility of these independently tunable mechanical/biochemistry gels, and that mechanical confinement in stiffer microenvironments may increase cell proliferation.

Lipoteichoic acid synthesis inhibition in combination with antibiotics abrogates growth of multidrug-resistant Enterococcus faecium.

PubMed

Paganelli, Fernanda L; van de Kamer, Tim; Brouwer, Ellen C; Leavis, Helen L; Woodford, Neil; Bonten, Marc J M; Willems, Rob J L; Hendrickx, Antoni P A

2017-03-01

Enterococcus faecium is a multidrug-resistant (MDR) nosocomial pathogen causing significant morbidity in debilitated patients. New antimicrobials are needed to treat antibiotic-resistant E. faecium infections in hospitalised patients. E. faecium incorporates lipoteichoic acid (LTA) (1,3-polyglycerol-phosphate linked to glycolipid) in its cell wall. The small-molecule inhibitor 1771 [2-oxo-2-(5-phenyl-1,3,4-oxadiazol-2-ylamino)ethyl 2-naphtho[2,1-b]furan-1-ylacetate] specifically blocks the activity of Staphylococcus aureus LtaS synthase, which polymerises 1,3-glycerolphosphate into LTA polymers. Here we characterised the effects of the small-molecule inhibitor 1771 on the growth of E. faecium isolates, alone (28 strains) or in combination with the antibiotics vancomycin, daptomycin, ampicillin, gentamicin or linezolid (15 strains), and on biofilm formation (16 strains). Inhibition of LTA synthesis at the surface of the cell by compound 1771 in combination with current antibiotic therapy abrogates enterococcal growth in vitro but does not affect mature E. faecium biofilms. Targeting LTA synthesis may provide new possibilities to treat MDR E. faecium infections. Copyright © 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

Genome-wide mRNA processing in methanogenic archaea reveals post-transcriptional regulation of ribosomal protein synthesis

PubMed Central

Qi, Lei; Yue, Lei; Feng, Deqin; Qi, Fengxia

2017-01-01

Abstract Unlike stable RNAs that require processing for maturation, prokaryotic cellular mRNAs generally follow an ‘all-or-none’ pattern. Herein, we used a 5΄ monophosphate transcript sequencing (5΄P-seq) that specifically captured the 5΄-end of processed transcripts and mapped the genome-wide RNA processing sites (PSSs) in a methanogenic archaeon. Following statistical analysis and stringent filtration, we identified 1429 PSSs, among which 23.5% and 5.4% were located in 5΄ untranslated region (uPSS) and intergenic region (iPSS), respectively. A predominant uridine downstream PSSs served as a processing signature. Remarkably, 5΄P-seq detected overrepresented uPSS and iPSS in the polycistronic operons encoding ribosomal proteins, and the majority upstream and proximal ribosome binding sites, suggesting a regulatory role of processing on translation initiation. The processed transcripts showed increased stability and translation efficiency. Particularly, processing within the tricistronic transcript of rplA-rplJ-rplL enhanced the translation of rplL, which can provide a driving force for the 1:4 stoichiometry of L10 to L12 in the ribosome. Growth-associated mRNA processing intensities were also correlated with the cellular ribosomal protein levels, thereby suggesting that mRNA processing is involved in tuning growth-dependent ribosome synthesis. In conclusion, our findings suggest that mRNA processing-mediated post-transcriptional regulation is a potential mechanism of ribosomal protein synthesis and stoichiometry. PMID:28520982

Ultrasonication-assisted synthesis of high aspect ratio gold nanowires on a graphene template and investigation of their growth mechanism.

PubMed

Xin, Wenbo; De Rosa, Igor M; Cao, Yang; Yin, Xunqian; Yu, Hang; Ye, Peiyi; Carlson, Larry; Yang, Jenn-Ming

2018-04-19

We report a facile synthesis of Au nanowires (AuNWs) with a high aspect ratio (l/D) of up to 5000 on a plasma activated graphene template with ultrasound assistance. We demonstrate that the ultrasonication induced symmetry breaking of Au clusters facilitates the growth of AuNWs from the embryonic stages. Furthermore, the growth mechanism of AuNWs is systematically investigated using high resolution electron transmission microscopy (HRTEM), which reveals the unique role of the defective graphene template in directing the growth of AuNWs.

Lyme disease and relapsing fever Borrelia elongate through zones of peptidoglycan synthesis that mark division sites of daughter cells.

PubMed

Jutras, Brandon Lyon; Scott, Molly; Parry, Bradley; Biboy, Jacob; Gray, Joe; Vollmer, Waldemar; Jacobs-Wagner, Christine

2016-08-16

Agents that cause Lyme disease, relapsing fever, leptospirosis, and syphilis belong to the phylum Spirochaetae-a unique lineage of bacteria most known for their long, spiral morphology. Despite the relevance to human health, little is known about the most fundamental aspects of spirochete growth. Here, using quantitative microscopy to track peptidoglycan cell-wall synthesis, we found that the Lyme disease spirochete Borrelia burgdorferi displays a complex pattern of growth. B. burgdorferi elongates from discrete zones that are both spatially and temporally regulated. In addition, some peptidoglycan incorporation occurs along the cell body, with the notable exception of a large region at the poles. Newborn cells inherit a highly active zone of peptidoglycan synthesis at midcell that contributes to elongation for most of the cell cycle. Concomitant with the initiation of nucleoid separation and cell constriction, second and third zones of elongation are established at the 1/4 and 3/4 cellular positions, marking future sites of division for the subsequent generation. Positioning of elongation zones along the cell is robust to cell length variations and is relatively precise over long distances (>30 µm), suggesting that cells ‟sense" relative, as opposed to absolute, cell length to establish zones of peptidoglycan synthesis. The transition from one to three zones of peptidoglycan growth during the cell cycle is also observed in relapsing fever Borrelia. However, this mode of growth does not extend to representative species from other spirochetal genera, suggesting that this distinctive growth mode represents an evolutionary divide in the spirochete phylum.

RAPTOR controls developmental growth transitions by altering the hormonal and metabolic balance.

PubMed

Salem, Mohamed A; Li, Yan; Bajdzienko, Krzysztof; Fisahn, Joachim; Watanabe, Mutsumi; Hoefgen, Rainer; Schöttler, Mark Aurel; Giavalisco, Patrick

2018-04-23

Vegetative growth requires the systemic coordination of numerous cellular processes, which are controlled by regulatory proteins that monitor extra- and intra-cellular cues and translate them into growth decisions. In eukaryotes, one of the central factors regulating growth is the Ser/Thr protein kinase Target of Rapamycin (TOR), which forms complexes with regulatory proteins. To understand the function of one such regulatory protein, Regulatory-Associated Protein of TOR 1B (RAPTOR1B) in plants, we analyzed the effect of raptor1b mutations on growth and physiology in Arabidopsis thaliana by detailed phenotyping, metabolomic, lipidomic, and proteomic analysis. Mutation of RAPTR1B resulted in a strong reduction of TOR kinase activity, leading to massive changes in central carbon and nitrogen metabolism, accumulation of excess starch, and induction of autophagy. These shifts led to a significant, reduction of plant growth that occurred non-linearly during developmental stage transtions.. This phenotype was accompanied by changes in cell morphology and tissue anatomy. In contrast to previous studies in rice, we found that the Arabidopsis raptor1b mutation did not affect chloroplast development or photosynthetic electron transport efficiency; however, it resulted in decreased CO2 assimilation rate and increased stomatal conductance. The raptor1b mutants also had reduced abscisic acid levels. Surprisingly, ABA feeding experiments resulted in partial complementation of the growth phenotypes, indicating the tight interaction between TOR function and hormone synthesis and signaling in plants. {copyright, serif} 2018 American Society of Plant Biologists. All rights reserved.

[Antifungals cellular targets and mechanisms of resistance].

PubMed

Accoceberry, Isabelle; Noël, Thierry

2006-01-01

Antifungals of systemic use for the treatment of invasive fungal infections belong to four main chemical families which have globally three cellular targets in fungal cells: fluorinated pyrimidines act on deoxyribonucleic acid (DNA) replication and protein synthesis; polyenes and azoles are toxic for ergosterol and its biosynthetic pathway; lipopeptides inhibit the synthesis of cell wall beta glucans. The resistance mechanisms that are developed by some fungi begin to be well understood particularly in Candida yeasts. The underlying bases of these mechanisms are either mutations that modify the antifungal target, or that block access to the target, and, on the other hand, the overexpression of genes encoding the target, or some membrane proteins involved in the active efflux of antifungal drugs.

Properties, synthesis, and growth mechanisms of carbon nanotubes with special focus on thermal chemical vapor deposition.

PubMed

Nessim, Gilbert D

2010-08-01

Carbon nanotubes (CNTs) have been extensively investigated in the last decade because their superior properties could benefit many applications. However, CNTs have not yet made a major leap into industry, especially for electronic devices, because of fabrication challenges. This review provides an overview of state-of-the-art of CNT synthesis techniques and illustrates their major technical difficulties. It also charts possible in situ analyses and new reactor designs that might enable commercialization. After a brief description of the CNT properties and of the various techniques used to synthesize substrate-free CNTs, the bulk of this review analyzes chemical vapor deposition (CVD). This technique receives special attention since it allows CNTs to be grown in predefined locations, provides a certain degree of control of the types of CNTs grown, and may have the highest chance to succeed commercially. Understanding the primary growth mechanisms at play during CVD is critical for controlling the properties of the CNTs grown and remains the major hurdle to overcome. Various factors that influence CNT growth receive a special focus: choice of catalyst and substrate materials, source gases, and process parameters. This review illustrates important considerations for in situ characterization and new reactor designs that may enable researchers to better understand the physical growth mechanisms and to optimize the synthesis of CNTs, thus contributing to make carbon nanotubes a manufacturing reality.

Chemo-enzymatic synthesis of isotopically labeled nicotinamide riboside.

PubMed

Tran, Ai; Yokose, Ryota; Cen, Yana

2018-05-15

As a cofactor for numerous reactions, NAD+ is found widely dispersed across many maps of cellular metabolism. This core redox role alone makes the biosynthesis of NAD+ of great interest. Recent studies have revealed new biological roles for NAD+ as a substrate for diverse enzymes that regulate a broad spectrum of key cellular tasks. These NAD+-consuming enzymes further highlight the importance of understanding NAD+ biosynthetic pathways. In this study, we developed a chemo-enzymatic synthesis of isotopically labeled NAD+ precursor, nicotinamide riboside (NR). The synthesis of NR isotopomers allowed us to unambiguously determine that NR is efficiently converted to NAD+ in the cellular environment independent of degradation to nicotinamide, and it is incorporated into NAD+ in its intact form. The versatile synthetic method along with the isotopically labeled NRs will provide powerful tools to further decipher the important yet complicated NAD+ metabolism.

A parallelized three-dimensional cellular automaton model for grain growth during additive manufacturing

NASA Astrophysics Data System (ADS)

Lian, Yanping; Lin, Stephen; Yan, Wentao; Liu, Wing Kam; Wagner, Gregory J.

2018-05-01

In this paper, a parallelized 3D cellular automaton computational model is developed to predict grain morphology for solidification of metal during the additive manufacturing process. Solidification phenomena are characterized by highly localized events, such as the nucleation and growth of multiple grains. As a result, parallelization requires careful treatment of load balancing between processors as well as interprocess communication in order to maintain a high parallel efficiency. We give a detailed summary of the formulation of the model, as well as a description of the communication strategies implemented to ensure parallel efficiency. Scaling tests on a representative problem with about half a billion cells demonstrate parallel efficiency of more than 80% on 8 processors and around 50% on 64; loss of efficiency is attributable to load imbalance due to near-surface grain nucleation in this test problem. The model is further demonstrated through an additive manufacturing simulation with resulting grain structures showing reasonable agreement with those observed in experiments.

A parallelized three-dimensional cellular automaton model for grain growth during additive manufacturing

NASA Astrophysics Data System (ADS)

Lian, Yanping; Lin, Stephen; Yan, Wentao; Liu, Wing Kam; Wagner, Gregory J.

2018-01-01

In this paper, a parallelized 3D cellular automaton computational model is developed to predict grain morphology for solidification of metal during the additive manufacturing process. Solidification phenomena are characterized by highly localized events, such as the nucleation and growth of multiple grains. As a result, parallelization requires careful treatment of load balancing between processors as well as interprocess communication in order to maintain a high parallel efficiency. We give a detailed summary of the formulation of the model, as well as a description of the communication strategies implemented to ensure parallel efficiency. Scaling tests on a representative problem with about half a billion cells demonstrate parallel efficiency of more than 80% on 8 processors and around 50% on 64; loss of efficiency is attributable to load imbalance due to near-surface grain nucleation in this test problem. The model is further demonstrated through an additive manufacturing simulation with resulting grain structures showing reasonable agreement with those observed in experiments.

Isolation of a Mutant of Salmonella typhimurium Dependent on D-Arabinose-5-phosphate for Growth and Synthesis of 3-Deoxy-D-mannoctulosonate (Ketodeoxyoctonate)

PubMed Central

Rick, P. D.; Osborn, M. J.

1972-01-01

A new type of auxotrophic mutant of Salmonella typhimurium has been isolated that is defective in the synthesis of the 3-deoxy-D-mannooctulosonate (ketodeoxyoctonate) region of the lipopolysaccharide and requires D-arabinose-5-phosphate for growth. Genetic and biochemical evidence indicated that the mutant defect was due to an altered ketodeoxyoctonate-8-phosphate synthetase with an apparent Km for D-arabinose-5-phosphate 35-fold higher than that of the parental enzyme. As a result of this enzymatic lesion, the mutant strain was dependent on exogenous D-arabinose-5-phosphate both for growth and for synthesis of a complete lipopolysaccharide. PMID:4566459

Molecular and Cellular Biophysics

NASA Astrophysics Data System (ADS)

Jackson, Meyer B.

2006-01-01

Molecular and Cellular Biophysics provides advanced undergraduate and graduate students with a foundation in the basic concepts of biophysics. Students who have taken physical chemistry and calculus courses will find this book an accessible and valuable aid in learning how these concepts can be used in biological research. The text provides a rigorous treatment of the fundamental theories in biophysics and illustrates their application with examples. Conformational transitions of proteins are studied first using thermodynamics, and subsequently with kinetics. Allosteric theory is developed as the synthesis of conformational transitions and association reactions. Basic ideas of thermodynamics and kinetics are applied to topics such as protein folding, enzyme catalysis and ion channel permeation. These concepts are then used as the building blocks in a treatment of membrane excitability. Through these examples, students will gain an understanding of the general importance and broad applicability of biophysical principles to biological problems. Offers a unique synthesis of concepts across a wide range of biophysical topics Provides a rigorous theoretical treatment, alongside applications in biological systems Author has been teaching biophysics for nearly 25 years

Wall mechanics and exocytosis define the shape of growth domains in fission yeast.

PubMed

Abenza, Juan F; Couturier, Etienne; Dodgson, James; Dickmann, Johanna; Chessel, Anatole; Dumais, Jacques; Carazo Salas, Rafael E

2015-10-12

The amazing structural variety of cells is matched only by their functional diversity, and reflects the complex interplay between biochemical and mechanical regulation. How both regulatory layers generate specifically shaped cellular domains is not fully understood. Here, we report how cell growth domains are shaped in fission yeast. Based on quantitative analysis of cell wall expansion and elasticity, we develop a model for how mechanics and cell wall assembly interact and use it to look for factors underpinning growth domain morphogenesis. Surprisingly, we find that neither the global cell shape regulators Cdc42-Scd1-Scd2 nor the major cell wall synthesis regulators Bgs1-Bgs4-Rgf1 are reliable predictors of growth domain geometry. Instead, their geometry can be defined by cell wall mechanics and the cortical localization pattern of the exocytic factors Sec6-Syb1-Exo70. Forceful re-directioning of exocytic vesicle fusion to broader cortical areas induces proportional shape changes to growth domains, demonstrating that both features are causally linked.

Monosaccharides as Scaffolds for the Synthesis of Novel Compounds

NASA Astrophysics Data System (ADS)

Murphy, Paul V.; Velasco-Torrijos, Trinidad

This chapter focuses on monosaccharides and scaffolds their derivatives as scaffolds for the synthesis of primarily bioactive compounds. Such carbohydrate derivatives have been designed to modulate mainly protein-protein and peptide-protein interactions although modulators of carbohydrate-protein and carbohydrate-nucleic acid interactions have also been of interest. The multiple hydroxyl groups that are present on saccharides have made pyranose, furanose and iminosugars ideal templates or scaffolds to which recognition or pharmacophoric groups can be grafted to generate novel compounds for medicinal chemistry. The synthesis of compounds for evaluations require strategies for regioselective reactions of saccharide hydroxyl groups and use of orthogonally stable protecting groups. Syntheses have been carried out on the solid phase and in solution. Also the use of uronic acids, amino sugars and sugar amino acids has facilitated the synthesis of peptidomimetics and prospecting libraries as they enable, through presence of amino or carboxylic acid groups, chemoselective approaches to be employed in solution and on solid phase. Sugar amino acids are readily incorporated, as peptide isosteres, to generate sugar-peptide hybrids or for the synthesis of novel carbopeptoids . The synthesis of new cyclic compounds, derived in part from saccharides, and their application as scaffolds is an emerging area and recent examples include spirocyclic compounds, benzodiazepine-saccharide hybrids and macrolide-saccharide hybrids. Potent bioactive saccharide derivatives have been identified that include enzyme inhibitors , somatostatin receptor ligands, integrin ligands, anti-viral compounds, shiga toxin inhibitors and cell growth inhibitors. Some saccharide derivatives have demonstrated improved cellular permeability when compared with peptides and are in clinical trials.

Cellular Viscosity in Prokaryotes and Thermal Stability of Low Molecular Weight Biomolecules.

PubMed

Cuecas, Alba; Cruces, Jorge; Galisteo-López, Juan F; Peng, Xiaojun; Gonzalez, Juan M

2016-08-23

Some low molecular weight biomolecules, i.e., NAD(P)H, are unstable at high temperatures. The use of these biomolecules by thermophilic microorganisms has been scarcely analyzed. Herein, NADH stability has been studied at different temperatures and viscosities. NADH decay increased at increasing temperatures. At increasing viscosities, NADH decay rates decreased. Thus, maintaining relatively high cellular viscosity in cells could result in increased stability of low molecular weight biomolecules (i.e., NADH) at high temperatures, unlike what was previously deduced from studies in diluted water solutions. Cellular viscosity was determined using a fluorescent molecular rotor in various prokaryotes covering the range from 10 to 100°C. Some mesophiles showed the capability of changing cellular viscosity depending on growth temperature. Thermophiles and extreme thermophiles presented a relatively high cellular viscosity, suggesting this strategy as a reasonable mechanism to thrive under these high temperatures. Results substantiate the capability of thermophiles and extreme thermophiles (growth range 50-80°C) to stabilize and use generally considered unstable, universal low molecular weight biomolecules. In addition, this study represents a first report, to our knowledge, on cellular viscosity measurements in prokaryotes and it shows the dependency of prokaryotic cellular viscosity on species and growth temperature. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Growth hormone stimulates protein synthesis during hypocaloric parenteral nutrition. Role of hormonal-substrate environment.

PubMed Central

Manson, J M; Smith, R J; Wilmore, D W

1988-01-01

The influence of growth hormone (GH) on protein metabolism and fuel utilization was investigated in eight paired studies of normal volunteers. GH (10 mg) was given daily during one period, and saline was injected during control studies. For 6 days, subjects received parenteral nutrition that provided adequate dietary nitrogen, vitamin, and minerals, but energy intake varied to provide 30-100% of requirements. On Day 7, the feedings were discontinued and an oral glucose load (100 g) was administered. The level of energy intake did not markedly influence the actions of GH. During nutrient infusions, GH caused positive nitrogen balance (1.0 +/- 0.3 g/m2/day vs. -1.2 +/- 0.3 in controls, p less than 0.001) and increased protein synthesis (16.8 +/- 0.7 g N/m2/day vs. 13.9 +/- 0.8, p less than 0.01). No change in the rate of protein breakdown or excretion of 3-methylhistidine occurred. GH was associated with an increase in insulin and insulin-like growth factor-I concentrations (IGF-I, 9.1 +/- 0.6 IU/ml vs. 3.3 +/- 0.5, p less than 0.001). After discontinuation of the parenteral nutrition and administration of the oral glucose load, glucose concentrations tended to be higher after GH; however, despite a two- to threefold increase in insulin response, muscle glucose uptake was attenuated (1.10 +/- 0.19 g/kg forearm vs. 1.64 +/- 0.30 in controls, p less than 0.05). Compared with control conditions, GH appeared to attenuate the increase in amino acid nitrogen efflux from muscle after the administration of oral glucose. These data demonstrate that the protein anabolic effect of GH, which occurs even during hypocaloric feedings, is related to multiple mechanisms that favor protein synthesis. These include the increase in plasma concentrations of GH, insulin IGF-I and fat utilization. GH administration results in a hormonal-substrate environment that favors nitrogen retention and protein synthesis. GH may be beneficial in promoting protein synthesis in surgical patients

Cellular energy metabolism maintains young status in old queen honey bees (Apis mellifera).

PubMed

Lu, Cheng-Yen; Qiu, Jiantai Timothy; Hsu, Chin-Yuan

2018-05-02

Trophocytes and oenocytes of queen honey bees are used in studies of cellular longevity, but their cellular energy metabolism with age is poorly understood. In this study, the molecules involved in cellular energy metabolism were evaluated in the trophocytes and oenocytes of young and old queen bees. The findings indicated that there were no significant differences between young and old queen bees in β-oxidation, glycolysis, and protein synthesis. These results indicate that the cellular energy metabolism of trophocytes and oenocytes in old queen bees is similar to young queen bees and suggests that maintaining cellular energy metabolism in a young status may be associated with the longevity of queen bees. Fat and glycogen accumulation increased with age indicating that old queen bees are older than young queen bees. © 2018 Wiley Periodicals, Inc.

Cellular compartmentalization of secondary metabolism

PubMed Central

Kistler, H. Corby; Broz, Karen

2015-01-01

Fungal secondary metabolism is often considered apart from the essential housekeeping functions of the cell. However, there are clear links between fundamental cellular metabolism and the biochemical pathways leading to secondary metabolite synthesis. Besides utilizing key biochemical precursors shared with the most essential processes of the cell (e.g., amino acids, acetyl CoA, NADPH), enzymes for secondary metabolite synthesis are compartmentalized at conserved subcellular sites that position pathway enzymes to use these common biochemical precursors. Co-compartmentalization of secondary metabolism pathway enzymes also may function to channel precursors, promote pathway efficiency and sequester pathway intermediates and products from the rest of the cell. In this review we discuss the compartmentalization of three well-studied fungal secondary metabolite biosynthetic pathways for penicillin G, aflatoxin and deoxynivalenol, and summarize evidence used to infer subcellular localization. We also discuss how these metabolites potentially are trafficked within the cell and may be exported. PMID:25709603

The cellular response to vascular endothelial growth factors requires co-ordinated signal transduction, trafficking and proteolysis

PubMed Central

Smith, Gina A.; Fearnley, Gareth W.; Tomlinson, Darren C.; Harrison, Michael A.; Ponnambalam, Sreenivasan

2015-01-01

VEGFs (vascular endothelial growth factors) are a family of conserved disulfide-linked soluble secretory glycoproteins found in higher eukaryotes. VEGFs mediate a wide range of responses in different tissues including metabolic homoeostasis, cell proliferation, migration and tubulogenesis. Such responses are initiated by VEGF binding to soluble and membrane-bound VEGFRs (VEGF receptor tyrosine kinases) and co-receptors. VEGF and receptor splice isoform diversity further enhances complexity of membrane protein assembly and function in signal transduction pathways that control multiple cellular responses. Different signal transduction pathways are simultaneously activated by VEGFR–VEGF complexes with membrane trafficking along the endosome–lysosome network further modulating signal output from multiple enzymatic events associated with such pathways. Balancing VEGFR–VEGF signal transduction with trafficking and proteolysis is essential in controlling the intensity and duration of different intracellular signalling events. Dysfunction in VEGF-regulated signal transduction is important in chronic disease states including cancer, atherosclerosis and blindness. This family of growth factors and receptors is an important model system for understanding human disease pathology and developing new therapeutics for treating such ailments. PMID:26285805

Step-Growth Polymerization.

ERIC Educational Resources Information Center

Stille, J. K.

1981-01-01

Following a comparison of chain-growth and step-growth polymerization, focuses on the latter process by describing requirements for high molecular weight, step-growth polymerization kinetics, synthesis and molecular weight distribution of some linear step-growth polymers, and three-dimensional network step-growth polymers. (JN)

Arachidonic acid stimulates DNA synthesis in brown preadipocytes through the activation of protein kinase C and MAPK.

PubMed

Garcia, Bibian; Martinez-de-Mena, Raquel; Obregon, Maria-Jesus

2012-10-01

Arachidonic acid (AA) is a polyunsaturated fatty acid that stimulates the proliferation of many cellular types. We studied the mitogenic potential of AA in rat brown preadipocytes in culture and the signaling pathways involved. AA is a potent mitogen which induces 4-fold DNA synthesis in brown preadipocytes. The AA mitogenic effect increases by NE addition. AA also increases the mitogenic action of different growth factor combinations. Other unsaturated and saturated fatty acids do not stimulate DNA synthesis to the same extent as AA. We analyzed the role of PKC and MEK/MAPK signaling pathways. PKC inhibition by bisindolilmaleimide I (BIS) abolishes AA and phorbol ester stimulation of DNA synthesis and reduces the mitogenic activity of different growth factors in brown preadipocytes. Brown preadipocytes in culture express PKC α, δ, ε and ζ isoforms. Pretreatment with high doses of the phorbol ester PDBu, induces downregulation of PKCs ε and δ and reproduces the effect of BIS indicating that AA-dependent induction of DNA synthesis requires PKC activity. AA also activates MEK/MAPK pathway and the inhibition of MEK activity inhibits AA stimulation of DNA synthesis and brown adipocyte proliferation. Inhibition of PKC δ by rottlerin abolishes AA-dependent stimulation of DNA synthesis and MAPK activation, whereas PKC ε inhibition does not produce any effect. In conclusion, our results identify AA as a potent mitogen for brown adipocytes and demonstrate the involvement of the PDBu-sensitive PKC δ isoform and MEK/MAPK pathway in AA-induced proliferation of brown adipocytes. Increased proliferative activity might increase the thermogenic capacity of brown fat. Copyright © 2012 Elsevier B.V. All rights reserved.

Retinoic acid-induced alveolar cellular growth does not improve function after right pneumonectomy.

PubMed

Dane, D Merrill; Yan, Xiao; Tamhane, Rahul M; Johnson, Robert L; Estrera, Aaron S; Hogg, Deborah C; Hogg, Richard T; Hsia, Connie C W

2004-03-01

To determine whether all-trans retinoic acid (RA) treatment enhances lung function during compensatory lung growth in fully mature animals, adult male dogs (n = 4) received 2 mg x kg(-1) x day(-1) po RA 4 days/wk beginning the day after right pneumonectomy (R-PNX, 55-58% resection). Litter-matched male R-PNX controls (n = 4) received placebo. After 3 mo, transpulmonary pressure (TPP)-lung volume relationship, diffusing capacities for carbon monoxide and nitric oxide, cardiac output, and septal volume (V(tiss-RB)) were measured under anesthesia by a rebreathing technique at two lung volumes. Lung air and tissue volumes (V(air-CT) and V(tiss-CT)) were also measured from high-resolution computerized tomographic (CT) scans at a constant TPP. In RA-treated dogs compared with controls, TPP-lung volume relationships were similar. Diffusing capacities for carbon monoxide and nitric oxide were significantly impaired at a lower lung volume but similar at a high lung volume. Whereas V(tiss-RB) was significantly lower at both lung volumes in RA-treated animals, V(air-CT) and V(tiss-CT) were not different between groups; results suggest uneven distribution of ventilation consistent with distortion of alveolar geometry and/or altered small airway function induced by RA. We conclude that RA does not improve resting pulmonary function during the early months after R-PNX despite histological evidence of its action in enhancing alveolar cellular growth in the remaining lung.

Molecular cellular mechanisms of peptide regulation of melatonin synthesis in pinealocyte culture.

PubMed

Khavinson, V Kh; Linkova, N S; Kvetnoy, I M; Kvetnaia, T V; Polyakova, V O; Korf, H-W

2012-06-01

The effects of epithalone and vilone peptides on the synthesis of melatonin and factors involved in this process, arylalkylamine-N-acetyltransferase (AANAT) enzyme and pCREB transcription protein, were studied in rat pinealocyte culture. Epithalone stimulated AANAT and pCREB synthesis and increased melatonin level in culture medium. Simultaneous addition of norepinephrine and peptides into the culture potentiated the expression of AANAT and pCREB.

Penta-Twinned Copper Nanorods: Facile Synthesis via Seed-Mediated Growth and Their Tunable Plasmonic Properties

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

Luo, Ming; Ruditskiy, Aleksey; Peng, Hsin-Chieh

When seed-mediated growth is used as a versatile approach to the synthesis of penta-twinned Cu nanorods with uniform diameters and controllable aspect ratios is reported. The success of this approach relies on our recent synthesis of uniform Pd decahedra, with sizes in the range of 6–20 nm. The Pd decahedral seeds can direct the heterogeneous nucleation and growth of Cu along the fivefold axis to produce nanorods with uniform diameters defined by the lateral dimension of the original seeds. Due to a large mismatch in the lattice constants between Cu and Pd (7.1%), the deposited Cu is forced to growmore » along one side of the Pd decahedral seed, generating a nanorod with an asymmetric distribution of Cu, with the Pd seed situated at one of the two ends. According to extinction spectra, the as-obtained Cu nanorods can be stored in water under the ambient conditions for at least six months without noticeable degradation. The resulting stability allows us to systematically investigate the size-dependent surface plasmon resonance properties of the penta-twinned Cu nanorods. With the nanorod transverse modes positioned at 560 nm, the longitudinal modes can be readily tuned from the visible to the near-infrared region by controlling the aspect ratio.« less

Penta-Twinned Copper Nanorods: Facile Synthesis via Seed-Mediated Growth and Their Tunable Plasmonic Properties

DOE PAGES

Luo, Ming; Ruditskiy, Aleksey; Peng, Hsin-Chieh; ...

2016-01-07

When seed-mediated growth is used as a versatile approach to the synthesis of penta-twinned Cu nanorods with uniform diameters and controllable aspect ratios is reported. The success of this approach relies on our recent synthesis of uniform Pd decahedra, with sizes in the range of 6–20 nm. The Pd decahedral seeds can direct the heterogeneous nucleation and growth of Cu along the fivefold axis to produce nanorods with uniform diameters defined by the lateral dimension of the original seeds. Due to a large mismatch in the lattice constants between Cu and Pd (7.1%), the deposited Cu is forced to growmore » along one side of the Pd decahedral seed, generating a nanorod with an asymmetric distribution of Cu, with the Pd seed situated at one of the two ends. According to extinction spectra, the as-obtained Cu nanorods can be stored in water under the ambient conditions for at least six months without noticeable degradation. The resulting stability allows us to systematically investigate the size-dependent surface plasmon resonance properties of the penta-twinned Cu nanorods. With the nanorod transverse modes positioned at 560 nm, the longitudinal modes can be readily tuned from the visible to the near-infrared region by controlling the aspect ratio.« less

Short communication: Arginase inhibition reduces the synthesis of casein in bovine mammary epithelial cells.

PubMed

Wang, M Z; Ding, L Y; Wang, C; Chen, L M; Loor, J J; Wang, H R

2017-05-01

The main purpose of this work was to determine the effect of arginase inhibition via N ω -hydroxy-nor-l-arginine (nor-NOHA) on casein synthesis in bovine mammary epithelial cells (BMEC). Passage 2 BMEC isolated from dairy cows were seeded to 6-well plates and randomly divided into 4 treatments: (1) control [Dulbecco's modified Eagle medium:Nutrient Mixture F-12 medium (DMEM/F12)]; (2) nor-NOHA (DMEM/F12 + 1 mmol/L nor-NOHA); (3) nor-NOHA + arginine (DMEM/F12 + 1 mmol/L nor-NOHA + 3.2 mmol/L Arg); and (4) nor-NOHA + ornithine (DMEM/F12+ 1 mmol/L nor-NOHA + 1 mmol/L Orn). Then, we determined the activity of enzymes related to Arg metabolism and casein synthesis in BMEC and the proliferation of cells. The addition of nor-NOHA reduced the activity of arginase and ornithine decarboxylase but had no effect on the activity of nitric oxide synthase, and these responses were the same at the gene expression level. In addition, supplementation of nor-NOHA in BMEC reduced cellular proliferation and casein synthesis. Addition of Arg to nor-NOHA resulted in cellular proliferation and casein synthesis similar to that of nor-NOHA alone. In contrast, addition of Orn to the medium with nor-NOHA increased the synthesis of casein and cellular proliferation compared with Nor-NOHA. In conclusion, suppression of the Arg-arginase-Orn pathway reduced casein synthesis and cellular proliferation, which indicated that this pathway is an important regulator of the synthesis of casein in BMEC. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

The Effect of New Zealand Kanuka, Manuka and Clover Honeys on Bacterial Growth Dynamics and Cellular Morphology Varies According to the Species

PubMed Central

Lu, Jing; Carter, Dee A.; Turnbull, Lynne; Rosendale, Douglas; Hedderley, Duncan; Stephens, Jonathan; Gannabathula, Swapna; Steinhorn, Gregor; Schlothauer, Ralf C.; Whitchurch, Cynthia B.; Harry, Elizabeth J.

2013-01-01

Treatment of chronic wounds is becoming increasingly difficult due to antibiotic resistance. Complex natural products with antimicrobial activity, such as honey, are now under the spotlight as alternative treatments to antibiotics. Several studies have shown honey to have broad-spectrum antibacterial activity at concentrations present in honey dressings, and resistance to honey has not been attainable in the laboratory. However not all honeys are the same and few studies have used honey that is well defined both in geographic and chemical terms. Here we have used a range of concentrations of clover honey and a suite of manuka and kanuka honeys from known geographical locations, and for which the floral source and concentration of methylglyoxal and hydrogen peroxide potential were defined, to determine their effect on growth and cellular morphology of four bacteria: Bacillus subtilis, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. While the general trend in effectiveness of growth inhibition was manuka>manuka-kanuka blend>kanuka>clover, the honeys had varying and diverse effects on the growth and cellular morphology of each bacterium, and each organism had a unique response profile to these honeys. P. aeruginosa showed a markedly different pattern of growth inhibition to the other three organisms when treated with sub-inhibitory concentrations of honey, being equally sensitive to all honeys, including clover, and the least sensitive to honey overall. While hydrogen peroxide potential contributed to the antibacterial activity of the manuka and kanuka honeys, it was never essential for complete growth inhibition. Cell morphology analysis also showed a varied and diverse set of responses to the honeys that included cell length changes, cell lysis, and alterations to DNA appearance. These changes are likely to reflect the different regulatory circuits of the organisms that are activated by the stress of honey treatment. PMID:23418472

Correction: Controlled synthesis of Bi25FeO40 with different morphologies: growth mechanism and enhanced photo-Fenton catalytic properties.

PubMed

Ji, Wenda; Li, Mingmeng; Zhang, Gaoke; Wang, Pei

2017-03-14

Correction for 'Controlled synthesis of Bi 25 FeO 40 with different morphologies: growth mechanism and enhanced photo-Fenton catalytic properties' by Wenda Ji et al., Dalton Trans., 2017, DOI: 10.1039/c6dt04864a.

Quantitative Analysis of Intra Urban Growth Modeling using socio economic agents by combining cellular automata model with agent based model

NASA Astrophysics Data System (ADS)

Singh, V. K.; Jha, A. K.; Gupta, K.; Srivastav, S. K.

2017-12-01

Recent studies indicate that there is a significant improvement in the urban land use dynamics through modeling at finer spatial resolutions. Geo-computational models such as cellular automata and agent based model have given evident proof regarding the quantification of the urban growth pattern with urban boundary. In recent studies, socio- economic factors such as demography, education rate, household density, parcel price of the current year, distance to road, school, hospital, commercial centers and police station are considered to the major factors influencing the Land Use Land Cover (LULC) pattern of the city. These factors have unidirectional approach to land use pattern which makes it difficult to analyze the spatial aspects of model results both quantitatively and qualitatively. In this study, cellular automata model is combined with generic model known as Agent Based Model to evaluate the impact of socio economic factors on land use pattern. For this purpose, Dehradun an Indian city is selected as a case study. Socio economic factors were collected from field survey, Census of India, Directorate of economic census, Uttarakhand, India. A 3X3 simulating window is used to consider the impact on LULC. Cellular automata model results are examined for the identification of hot spot areas within the urban area and agent based model will be using logistic based regression approach where it will identify the correlation between each factor on LULC and classify the available area into low density, medium density, high density residential or commercial area. In the modeling phase, transition rule, neighborhood effect, cell change factors are used to improve the representation of built-up classes. Significant improvement is observed in the built-up classes from 84 % to 89 %. However after incorporating agent based model with cellular automata model the accuracy improved from 89 % to 94 % in 3 classes of urban i.e. low density, medium density and commercial classes

Fabrication of cellular materials

NASA Astrophysics Data System (ADS)

Prud'homme, Robert K.; Aksay, Ilhan A.; Garg, Rajeev

1996-02-01

Nature uses cellular materials in applications requiring strength while, simultaneously, minimizing raw materials requirements. Minimizing raw materials is efficient both in terms of the energy expended by the organism to synthesize the structure and in terms of the strength- to-weight ratio of the structure. Wood is the most obvious example of cellular bio-materials, and it is the focus of other presentations in this symposium. The lightweight bone structure of birds is another excellent example where weight is a key criterion. The anchoring foot of the common muscle [Mytilus edulis] whereby it attaches itself to objects is a further example of a biological system that uses a foam to fill space and yet conserve on raw materials. In the case of the muscle the foam is water filled and the foot structure distributes stress over a larger area so that the strength of the byssal thread from which it is suspended is matched to the strength of interfacial attachment of the foot to a substrate. In these examples the synthesis and fabrication of the cellular material is directed by intercellular, genetically coded, biochemical reactions. The resulting cell sizes are microns in scale. Cellular materials at the next larger scale are created by organisms at the next higher level of integration. For example an African tree frog lays her eggs in a gas/fluid foam sack she builds on a branch overhanging a pond. The outside of the foam sack hardens in the sun and prevents water evaporation. The foam structure minimizes the amount of fluid that needs to be incorporated into the sack and minimizes its weight. However, as far as the developing eggs are concerned, they are in an aqueous medium, i.e. the continuous fluid phase of the foam. After precisely six days the eggs hatch, and the solidified outer wall re-liquefies and dumps the emerging tadpoles into the pond below. The bee honeycomb is an example of a cellular material with exquisite periodicity at millimeter length scales. The

A review on the synthesis, crystal growth, structure and physical properties of rare earth based quaternary intermetallic compounds

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

Mumbaraddi, Dundappa; Sarkar, Sumanta; Peter, Sebastian C., E-mail: sebastiancp@jncasr.ac.in

2016-04-15

This review highlights the synthesis and crystal growth of quaternary intermetallic compounds based on rare earth metals. In the first part of this review, we highlight briefly about intermetallics and their versatile properties in comparison to the constituent elements. In the next part, we have discussed about various synthesis techniques with more focus on the metal flux technique towards the well shaped crystal growth of novel compounds. In the subsequent parts, several disordered quaternary compounds have been reviewed and then outlined most known ordered quaternary compounds with their complex structure. A special attention has been given to the ordered compoundsmore » with structural description and relation to the parent binary and ternary compounds. The importance of electronic and structural feature is highlighted as the key roles in designing these materials for emerging applications. - Graphical abstract: Rare earth based quaternary intermetallic compounds crystallize in complex novel crystal structures. The diversity in the crystal structure may induce unique properties and can be considered them as future materials. - Highlights: • Crystal growth and crystal structure of quaternary rare earth based intermetallics. • Structural complexity of quaternary compounds in comparison to the parent compounds. • Novel quaternary compounds display unique crystal structure.« less

Genome-wide mRNA processing in methanogenic archaea reveals post-transcriptional regulation of ribosomal protein synthesis.

PubMed

Qi, Lei; Yue, Lei; Feng, Deqin; Qi, Fengxia; Li, Jie; Dong, Xiuzhu

2017-07-07

Unlike stable RNAs that require processing for maturation, prokaryotic cellular mRNAs generally follow an 'all-or-none' pattern. Herein, we used a 5΄ monophosphate transcript sequencing (5΄P-seq) that specifically captured the 5΄-end of processed transcripts and mapped the genome-wide RNA processing sites (PSSs) in a methanogenic archaeon. Following statistical analysis and stringent filtration, we identified 1429 PSSs, among which 23.5% and 5.4% were located in 5΄ untranslated region (uPSS) and intergenic region (iPSS), respectively. A predominant uridine downstream PSSs served as a processing signature. Remarkably, 5΄P-seq detected overrepresented uPSS and iPSS in the polycistronic operons encoding ribosomal proteins, and the majority upstream and proximal ribosome binding sites, suggesting a regulatory role of processing on translation initiation. The processed transcripts showed increased stability and translation efficiency. Particularly, processing within the tricistronic transcript of rplA-rplJ-rplL enhanced the translation of rplL, which can provide a driving force for the 1:4 stoichiometry of L10 to L12 in the ribosome. Growth-associated mRNA processing intensities were also correlated with the cellular ribosomal protein levels, thereby suggesting that mRNA processing is involved in tuning growth-dependent ribosome synthesis. In conclusion, our findings suggest that mRNA processing-mediated post-transcriptional regulation is a potential mechanism of ribosomal protein synthesis and stoichiometry. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

The effect of inhibitors of cellular RNA synthesis on stimulation of mouse encephalomyocarditis virus reproduction by poliovirus in HeLa and MIO cells.

PubMed

Shirman, G A; Maslova, S V

1978-05-01

Inoculation of HeLa and MIO cells with a guanidine-dependent mutant of poliovirus (gd-polio) in the absence of guanidine resulted in stimulation of mouse encephalomyocarditis (EMC) virus reproduction. No stimulation was found to occur in the presence of actinomycin D, on pre-treatment of the cells with cordycepin, or on their UV irradiation or enucleation. In contrast to HeLa cells, the enhancement of EMC virus reproduction by gd-polio in MIO cells required no current synthesis of cellular RNAs: it occurred in the presence of actinomycin D, upon UV irradiation of the cells or their enucleation. The possible mechanisms of the stimulating effect of poliovirus in HeLa and MIO cells are discussed.

The effect of tunicamycin on the glucose uptake, growth, and cellular adhesion in the protozoan parasite Crithidia fasciculata.

PubMed

Rojas, Robert; Segovia, Christopher; Trombert, Annette Nicole; Santander, Javier; Manque, Patricio

2014-10-01

Crithidia fasciculata represents a very interesting model organism to study biochemical, cellular, and genetic processes unique to members of the family of the Trypanosomatidae. Thus, C. fasciculata parasitizes several species of insects and has been widely used to test new therapeutic strategies against parasitic infections. By using tunicamycin, a potent inhibitor of glycosylation in asparaginyl residues of glycoproteins (N-glycosylation), we demonstrate that N-glycosylation in C. fasciculata cells is involved in modulating glucose uptake, dramatically impacting growth, and cell adhesion. C. fasciculata treated with tunicamycin was severely affected in their ability to replicate and to adhere to polystyrene substrates and losing their ability to aggregate into small and large groups. Moreover, under tunicamycin treatment, the parasites were considerably shorter and rounder and displayed alterations in cytoplasmic vesicles formation. Furthermore, glucose uptake was significantly impaired in a tunicamycin dose-dependent manner; however, no cytotoxic effect was observed. Interestingly, this effect was reversible. Thus, when tunicamycin was removed from the culture media, the parasites recovered its growth rate, cell adhesion properties, and glucose uptake. Collectively, these results suggest that changes in the tunicamycin-dependent glycosylation levels can influence glucose uptake, cell growth, and adhesion in the protozoan parasite C. fasciculata.

YB-1 Is Important for Late-Stage Embryonic Development, Optimal Cellular Stress Responses, and the Prevention of Premature Senescence

PubMed Central

Lu, Zhi Hong; Books, Jason T.; Ley, Timothy J.

2005-01-01

Proteins containing “cold shock” domains belong to the most evolutionarily conserved family of nucleic acid-binding proteins known among bacteria, plants, and animals. One of these proteins, YB-1, is widely expressed throughout development and has been implicated as a cell survival factor that regulates the transcription and/or translation of many cellular growth and death-related genes. For these reasons, YB-1 deficiency has been predicted to be incompatible with cell survival. However, the majority of YB-1−/− embryos develop normally up to embryonic day 13.5 (E13.5). After E13.5, YB-1−/− embryos exhibit severe growth retardation and progressive mortality, revealing a nonredundant role of YB-1 in late embryonic development. Fibroblasts derived from YB-1−/− embryos displayed a normal rate of protein synthesis and minimal alterations in the transcriptome and proteome but demonstrated reduced abilities to respond to oxidative, genotoxic, and oncogene-induced stresses. YB-1−/− cells under oxidative stress expressed high levels of the G1-specific CDK inhibitors p16Ink4a and p21Cip1 and senesced prematurely; this defect was corrected by knocking down CDK inhibitor levels with specific small interfering RNAs. These data suggest that YB-1 normally represses the transcription of CDK inhibitors, making it an important component of the cellular stress response signaling pathway. PMID:15899865

Protein synthesis in geostimulated root caps

NASA Technical Reports Server (NTRS)

Feldman, L. J.

1982-01-01

A study is presented of the processes occurring in the root cap of corn which are requisite for the formation of root cap inhibitor and which can be triggered or modulated by both light and gravity. The results of this study indicate the importance of protein synthesis for light-induced gravitropic bending in roots. Root caps in which protein synthesis is prevented are unable to induce downward bending. This suggests that light acts by stimulating proteins which are necessary for the translation of the gravitropic stimulus into a growth response (downward bending). The turnover of protein with time was also examined in order to determine whether light acts by stimulating the synthesis of unique proteins required for downward growth. It is found that auxin in combination with light allows for the translation of the gravitropic stimulus into a growth response at least in part through the modification of protein synthesis. It is concluded that unique proteins are stimulated by light and are involved in promoting the downward growth in roots which are responding to gravity.

Seedless Synthesis of Monodispersed Gold Nanorods with Remarkably High Yield: Synergistic Effect of Template Modification and Growth Kinetics Regulation.

PubMed

Liu, Kang; Bu, Yanru; Zheng, Yuanhui; Jiang, Xuchuan; Yu, Aibing; Wang, Huanting

2017-03-08

Gold nanorods (AuNRs) are versatile materials due to their broadly tunable optical properties associated with their anisotropic feature. Conventional seed-mediated synthesis is, however, not only limited by the operational complexity and over-sensitivity towards subtle changes of experimental conditions but also suffers from low yield (≈15 %). A facile seedless method is reported to overcome these challenges. Monodispersed AuNRs with high yield (≈100 %) and highly adjustable longitudinal surface plasmon resonance (LSPR) are reproducibly synthesized. The parameters that influence the AuNRs growth were thoroughly investigated in terms of growth kinetics and soft-template regulation, offering a better understanding of the template-based mechanism. The facile synthesis, broad tunability of LSRP, high reproducibility, high yield, and ease of scale-up make this method promising for the future mass production of monodispersed AuNRs for applications in catalysis, sensing, and biomedicine. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

[In vitro study over statins effects on cellular growth curves and its reversibility with mevalonate].

PubMed

Millan Núñez-Cortés, Jesús; Alvarez Rodriguez, Ysmael; Alvarez Novés, Granada; Recarte Garcia-Andrade, Carlos; Alvarez-Sala Walther, Luis

2014-01-01

HMG-CoA-Reductase inhibitors, also known as statins, are currently the most powerful cholesterol-lowering drugs available on the market. Clinical trials and experimental evidence suggest that statins have heavy anti-atherosclerotic effects. These are in part consequence of lipid lowering but also result from pleiotropic actions of the drugs. These so-called pleiotropic properties affect various aspects of cell function, inflammation, coagulation, and vasomotor activity. These effects are mediated either indirectly through LDL-c reduction or via a direct effect on cellular functions. Although many of the pleiotropic properties of statins may be a class effect, some may be unique to certain agents and account for differences in their pharmacological activity. So, although statins typically have similar effects on LDL-c levels, differences in chemical structure and pharmacokinetic profile can lead to variations in pleiotropic effects. In this paper we analize the in vitro effects of different statins over different cell lines from cells implicated in atherosclerotic process: endothelial cells, fibroblasts, and vascular muscular cells. In relation with our results we can proof that the effects of different dosis of different statins provides singular effects over growth curves of different cellular lines, a despite of a class-dependent effects. So, pleiotropic effects and its reversibility with mevalonate are different according with the molecule and the dosis. Copyright © 2013 Elsevier España, S.L. y SEA. All rights reserved.

Identification of Novel Human Breast Carcinoma (MDA-MB-231) Cell Growth Modulators from a Carbohydrate-Based Diversity Oriented Synthesis Library.

PubMed

Lenci, Elena; Innocenti, Riccardo; Biagioni, Alessio; Menchi, Gloria; Bianchini, Francesca; Trabocchi, Andrea

2016-10-20

The application of a cell-based growth inhibition on a library of skeletally different glycomimetics allowed for the selection of a hexahydro-2 H -furo[3,2- b ][1,4]oxazine compound as candidate inhibitors of MDA-MB-231 cell growth. Subsequent synthesis of analogue compounds and preliminary biological studies validated the selection of a valuable hit compound with a novel polyhydroxylated structure for the modulation of the breast carcinoma cell cycle mechanism.

Cellular context-dependent consequences of Apc mutations on gene regulation and cellular behavior.

PubMed

Hashimoto, Kyoichi; Yamada, Yosuke; Semi, Katsunori; Yagi, Masaki; Tanaka, Akito; Itakura, Fumiaki; Aoki, Hitomi; Kunisada, Takahiro; Woltjen, Knut; Haga, Hironori; Sakai, Yoshiharu; Yamamoto, Takuya; Yamada, Yasuhiro

2017-01-24

The spectrum of genetic mutations differs among cancers in different organs, implying a cellular context-dependent effect for genetic aberrations. However, the extent to which the cellular context affects the consequences of oncogenic mutations remains to be fully elucidated. We reprogrammed colon tumor cells in an Apc Min/+ (adenomatous polyposis coli) mouse model, in which the loss of the Apc gene plays a critical role in tumor development and subsequently, established reprogrammed tumor cells (RTCs) that exhibit pluripotent stem cell (PSC)-like signatures of gene expression. We show that the majority of the genes in RTCs that were affected by Apc mutations did not overlap with the genes affected in the intestine. RTCs lacked pluripotency but exhibited an increased expression of Cdx2 and a differentiation propensity that was biased toward the trophectoderm cell lineage. Genetic rescue of the mutated Apc allele conferred pluripotency on RTCs and enabled their differentiation into various cell types in vivo. The redisruption of Apc in RTC-derived differentiated cells resulted in neoplastic growth that was exclusive to the intestine, but the majority of the intestinal lesions remained as pretumoral microadenomas. These results highlight the significant influence of cellular context on gene regulation, cellular plasticity, and cellular behavior in response to the loss of the Apc function. Our results also imply that the transition from microadenomas to macroscopic tumors is reprogrammable, which underscores the importance of epigenetic regulation on tumor promotion.

Cellular context-dependent consequences of Apc mutations on gene regulation and cellular behavior

PubMed Central

Hashimoto, Kyoichi; Yamada, Yosuke; Semi, Katsunori; Yagi, Masaki; Tanaka, Akito; Itakura, Fumiaki; Aoki, Hitomi; Kunisada, Takahiro; Woltjen, Knut; Haga, Hironori; Sakai, Yoshiharu; Yamamoto, Takuya; Yamada, Yasuhiro

2017-01-01

The spectrum of genetic mutations differs among cancers in different organs, implying a cellular context-dependent effect for genetic aberrations. However, the extent to which the cellular context affects the consequences of oncogenic mutations remains to be fully elucidated. We reprogrammed colon tumor cells in an ApcMin/+ (adenomatous polyposis coli) mouse model, in which the loss of the Apc gene plays a critical role in tumor development and subsequently, established reprogrammed tumor cells (RTCs) that exhibit pluripotent stem cell (PSC)-like signatures of gene expression. We show that the majority of the genes in RTCs that were affected by Apc mutations did not overlap with the genes affected in the intestine. RTCs lacked pluripotency but exhibited an increased expression of Cdx2 and a differentiation propensity that was biased toward the trophectoderm cell lineage. Genetic rescue of the mutated Apc allele conferred pluripotency on RTCs and enabled their differentiation into various cell types in vivo. The redisruption of Apc in RTC-derived differentiated cells resulted in neoplastic growth that was exclusive to the intestine, but the majority of the intestinal lesions remained as pretumoral microadenomas. These results highlight the significant influence of cellular context on gene regulation, cellular plasticity, and cellular behavior in response to the loss of the Apc function. Our results also imply that the transition from microadenomas to macroscopic tumors is reprogrammable, which underscores the importance of epigenetic regulation on tumor promotion. PMID:28057861

Short-term administration of rhGH increases markers of cellular proliferation but not milk protein gene expression in normal lactating women

PubMed Central

Maningat, Patricia D.; Sen, Partha; Rijnkels, Monique; Hadsell, Darryl L.; Bray, Molly S.

2011-01-01

Growth hormone is one of few pharmacologic agents known to augment milk production in humans. We hypothesized that recombinant human GH (rhGH) increases the expression of cell proliferation and milk protein synthesis genes. Sequential milk and blood samples collected over four days were obtained from five normal lactating women. Following 24 h of baseline milk and blood sampling, rhGH (0.1 mg/kg/day) was administered subcutaneously once daily for 3 days. Gene expression changes were determined by microarray studies utilizing milk fat globule RNA isolated from each milk sample. Following rhGH administration, DNA synthesis and cell cycle genes were induced, while no significant changes were observed in the expression of milk synthesis genes. Expression of glycolysis and citric acid cycle genes were increased by day 4 compared with day 1, while lipid synthesis genes displayed a circadian-like pattern. Cell cycle gene upregulation occurred after a lag of ∼2 days, likely explaining the failure to increase milk production after only 3 days of rhGH treatment. We conclude that rhGH induces expression of cellular proliferation and metabolism genes but does not induce milk protein gene expression, as potential mechanisms for increasing milk production and could account for the known effect of rhGH to increase milk production following 7–10 days. PMID:21205870

Acute myotube protein synthesis regulation by IL-6-related cytokines.

PubMed

Gao, Song; Durstine, J Larry; Koh, Ho-Jin; Carver, Wayne E; Frizzell, Norma; Carson, James A

2017-11-01

IL-6 and leukemia inhibitory factor (LIF), members of the IL-6 family of cytokines, play recognized paradoxical roles in skeletal muscle mass regulation, being associated with both growth and atrophy. Overload or muscle contractions can induce a transient increase in muscle IL-6 and LIF expression, which has a regulatory role in muscle hypertrophy. However, the cellular mechanisms involved in this regulation have not been completely identified. The induction of mammalian target of rapamycin complex 1 (mTORC1)-dependent myofiber protein synthesis is an established regulator of muscle hypertrophy, but the involvement of the IL-6 family of cytokines in this process is poorly understood. Therefore, we investigated the acute effects of IL-6 and LIF administration on mTORC1 signaling and protein synthesis in C2C12 myotubes. The role of glycoprotein 130 (gp130) receptor and downstream signaling pathways, including phosphoinositide 3-kinase (PI3K)-Akt-mTORC1 and signal transducer and activator of transcription 3 (STAT3)-suppressor of cytokine signaling 3 (SOCS3), was investigated by administration of specific siRNA or pharmaceutical inhibitors. Acute administration of IL-6 and LIF induced protein synthesis, which was accompanied by STAT3 activation, Akt-mTORC1 activation, and increased SOCS3 expression. This induction of protein synthesis was blocked by both gp130 siRNA knockdown and Akt inhibition. Interestingly, STAT3 inhibition or Akt downstream mTORC1 signaling inhibition did not fully block the IL-6 or LIF induction of protein synthesis. SOCS3 siRNA knockdown increased basal protein synthesis and extended the duration of the protein synthesis induction by IL-6 and LIF. These results demonstrate that either IL-6 or LIF can activate gp130-Akt signaling axis, which induces protein synthesis via mTORC1-independent mechanisms in cultured myotubes. However, IL-6- or LIF-induced SOCS3 negatively regulates the activation of myotube protein synthesis. Copyright © 2017 the

Effect of penicillin on fatty acid synthesis and excretion in Streptococcus mutans BHT

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

Brissette, J.L.; Pieringer, R.A.

Treatment of exponentially growing cultures of Streptococcus mutans BHT with growth-inhibitory concentrations (0.2 microgram/ml) of benzylpenicillin stimulates the incorporation of (2-/sup 14/C) acetate into lipids excreted by the cells by as much as 69-fold, but does not change the amount of /sup 14/C incorporated into intracellular lipids. At this concentration of penicillin cellular lysis does not occur. The radioactive label is incorporated exclusively into the fatty acid moieties of the glycerolipids. During a 4-hr incubation in the presence of penicillin, the extracellular fatty acid ester concentration increases 1.5 fold, even though there is no growth or cellular lysis. An indicationmore » of the relative rate of fatty acid synthesis was most readily obtained by placing S. mutans BHT in a buffer containing /sup 14/C-acetate. Under these nongrowing conditions free fatty acids are the only lipids labeled, a factor which simplifies the assay. The addition of glycerol to the buffer causes all of the nonesterified fatty acids to be incorporated into glycerolipid. The cells excrete much of the lipid whether glycerol is present or not. Addition of penicillin to the nongrowth supporting buffer system does not stimulate the incorporation of (/sup 14/C)-acetate into fatty acids.« less

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

Accelerated Growth Rate Induced by Neonatal High-Protein Milk Formula Is Not Supported by Increased Tissue Protein Synthesis in Low-Birth-Weight Piglets

PubMed Central

Jamin, Agnès; Sève, Bernard; Thibault, Jean-Noël; Floc'h, Nathalie

2012-01-01

Low-birth-weight neonates are routinely fed a high-protein formula to promote catch-up growth and antibiotics are usually associated to prevent infection. Yet the effects of such practices on tissue protein metabolism are unknown. Baby pigs were fed from age 2 to 7 or 28 d with high protein formula with or without amoxicillin supplementation, in parallel with normal protein formula, to determine tissue protein metabolism modifications. Feeding high protein formula increased growth rate between 2 and 28 days of age when antibiotic was administered early in the first week of life. This could be explained by the occurrence of diarrhea when piglets were fed the high protein formula alone. Higher growth rate was associated with higher feed conversion and reduced protein synthesis rate in the small intestine, muscle and carcass, whereas proteolytic enzyme activities measured in these tissues were unchanged. In conclusion, accelerated growth rate caused by high protein formula and antibiotics was not supported by increased protein synthesis in muscle and carcass. PMID:22315674

Large-scale parallel lattice Boltzmann-cellular automaton model of two-dimensional dendritic growth

NASA Astrophysics Data System (ADS)

Jelinek, Bohumir; Eshraghi, Mohsen; Felicelli, Sergio; Peters, John F.

2014-03-01

An extremely scalable lattice Boltzmann (LB)-cellular automaton (CA) model for simulations of two-dimensional (2D) dendritic solidification under forced convection is presented. The model incorporates effects of phase change, solute diffusion, melt convection, and heat transport. The LB model represents the diffusion, convection, and heat transfer phenomena. The dendrite growth is driven by a difference between actual and equilibrium liquid composition at the solid-liquid interface. The CA technique is deployed to track the new interface cells. The computer program was parallelized using the Message Passing Interface (MPI) technique. Parallel scaling of the algorithm was studied and major scalability bottlenecks were identified. Efficiency loss attributable to the high memory bandwidth requirement of the algorithm was observed when using multiple cores per processor. Parallel writing of the output variables of interest was implemented in the binary Hierarchical Data Format 5 (HDF5) to improve the output performance, and to simplify visualization. Calculations were carried out in single precision arithmetic without significant loss in accuracy, resulting in 50% reduction of memory and computational time requirements. The presented solidification model shows a very good scalability up to centimeter size domains, including more than ten million of dendrites. Catalogue identifier: AEQZ_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEQZ_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, UK Licensing provisions: Standard CPC license, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 29,767 No. of bytes in distributed program, including test data, etc.: 3131,367 Distribution format: tar.gz Programming language: Fortran 90. Computer: Linux PC and clusters. Operating system: Linux. Has the code been vectorized or parallelized?: Yes. Program is parallelized using MPI

Coordination of Cellular Dynamics Contributes to Tooth Epithelium Deformations

PubMed Central

Morita, Ritsuko; Kihira, Miho; Nakatsu, Yousuke; Nomoto, Yohei; Ogawa, Miho; Ohashi, Kazumasa; Mizuno, Kensaku; Tachikawa, Tetsuhiko; Ishimoto, Yukitaka; Morishita, Yoshihiro; Tsuji, Takashi

2016-01-01

The morphologies of ectodermal organs are shaped by appropriate combinations of several deformation modes, such as invagination and anisotropic tissue elongation. However, how multicellular dynamics are coordinated during deformation processes remains to be elucidated. Here, we developed a four-dimensional (4D) analysis system for tracking cell movement and division at a single-cell resolution in developing tooth epithelium. The expression patterns of a Fucci probe clarified the region- and stage-specific cell cycle patterns within the tooth germ, which were in good agreement with the pattern of the volume growth rate estimated from tissue-level deformation analysis. Cellular motility was higher in the regions with higher growth rates, while the mitotic orientation was significantly biased along the direction of tissue elongation in the epithelium. Further, these spatio-temporal patterns of cellular dynamics and tissue-level deformation were highly correlated with that of the activity of cofilin, which is an actin depolymerization factor, suggesting that the coordination of cellular dynamics via actin remodeling plays an important role in tooth epithelial morphogenesis. Our system enhances the understanding of how cellular behaviors are coordinated during ectodermal organogenesis, which cannot be observed from histological analyses. PMID:27588418

Modulation of protein synthesis by polyamines.

PubMed

Igarashi, Kazuei; Kashiwagi, Keiko

2015-03-01

Polyamines are ubiquitous small basic molecules that play important roles in cell growth and viability. Since polyamines mainly exist as a polyamine-RNA complex, we looked for proteins whose synthesis is preferentially stimulated by polyamines at the level of translation, and thus far identified 17 proteins in Escherichia coli and 6 proteins in eukaryotes. The mechanisms of polyamine stimulation of synthesis of these proteins were investigated. In addition, the role of eIF5A, containing hypusine formed from spermidine, on protein synthesis is described. These results clearly indicate that polyamines and eIF5A contribute to cell growth and viability through modulation of protein synthesis. © 2015 International Union of Biochemistry and Molecular Biology.

Synthesis of Lipidated Proteins.

PubMed

Mejuch, Tom; Waldmann, Herbert

2016-08-17

Protein lipidation is one of the major post-translational modifications (PTM) of proteins. The attachment of the lipid moiety frequently determines the localization and the function of the lipoproteins. Lipidated proteins participate in many essential biological processes in eukaryotic cells, including vesicular trafficking, signal transduction, and regulation of the immune response. Malfunction of these cellular processes usually leads to various diseases such as cancer. Understanding the mechanism of cellular signaling and identifying the protein-protein and protein-lipid interactions in which the lipoproteins are involved is a crucial task. To achieve these goals, fully functional lipidated proteins are required. However, access to lipoproteins by means of standard expression is often rather limited. Therefore, semisynthetic methods, involving the synthesis of lipidated peptides and their subsequent chemoselective ligation to yield full-length lipoproteins, were developed. In this Review we summarize the commonly used methods for lipoprotein synthesis and the development of the corresponding chemoselective ligation techniques. Several key studies involving full-length semisynthetic lipidated Ras, Rheb, and LC3 proteins are presented.

Approximate probabilistic cellular automata for the dynamics of single-species populations under discrete logisticlike growth with and without weak Allee effects.

PubMed

Mendonça, J Ricardo G; Gevorgyan, Yeva

2017-05-01

We investigate one-dimensional elementary probabilistic cellular automata (PCA) whose dynamics in first-order mean-field approximation yields discrete logisticlike growth models for a single-species unstructured population with nonoverlapping generations. Beginning with a general six-parameter model, we find constraints on the transition probabilities of the PCA that guarantee that the ensuing approximations make sense in terms of population dynamics and classify the valid combinations thereof. Several possible models display a negative cubic term that can be interpreted as a weak Allee factor. We also investigate the conditions under which a one-parameter PCA derived from the more general six-parameter model can generate valid population growth dynamics. Numerical simulations illustrate the behavior of some of the PCA found.

NUTRITION OF CELLULAR SLIME MOLDS I.

PubMed Central

Hohl, Hans-Rudolf; Raper, Kenneth B.

1963-01-01

Hohl, Hans-Rudolf (University of Wisconsin, Madison) and Kenneth B. Raper. Nutrition of cullular slime molds. I. Growth on living and dead bacteria. J. Bacteriol. 85:191–198. 1963.—Methods for growing selected species of cellular slime molds in liquid culture on living and dead bacteria are described. Species investigated included Polysphondylium pallidum, P. violaceum, Dictyostelium discoideum, and D. purpureum. Maximal growth of myxamoebae occurred in suspensions of 1010 living bacteria (Escherichia coli B/r)/ml in Sörensen's phosphate buffer (pH 6.0), reaching a density of 107 to 2 × 107 cells/ml in 48 hr. The generation time for the different slime molds ranged from 2.4 hr for P. violaceum to 2.9 hr for D. discoideum (strain V-12). Good growth of P. pallidum occurred between pH 3.6 and 7.8. The slime molds grew less well on dead (autoclaved) than on living bacteria and, except for P. pallidum, the amount and rate of growth decreased markedly as the time of autoclaving was increased from 2.5 to 80 min. Bacteria killed with propylene oxide supported growth equal to those autoclaved for a few minutes. The myxamoebae were very sensitive to the osmotic pressure of the culture medium, especially in the presence of living bacteria, and addition of as little as 0.01 m NaCl caused a measurable decrease in slime mold growth. The culture techniques employed afford useful methods for investigating the nutritional requirements of the cellular slime molds, and the experiments described provide the bases for subsequent studies relating to the axenic cultivation of these singular microorganisms. Images PMID:13961228

New concept: cellular senescence in pathophysiology of cholangiocarcinoma.

PubMed

Sasaki, Motoko; Nakanuma, Yasuni

2016-01-01

Cholangiocarcinoma, a malignant tumor arising in the hepatobiliary system, presents with poor prognosis because of difficulty in its early detection/diagnosis. Recent progress revealed that cellular senescence may be involved in the pathophysiology of cholangiocarcinoma. Cellular senescence is defined as permanent growth arrest caused by several cellular injuries, such as oncogenic mutations and oxidative stress. "Oncogene-induced" and/or stress-induced senescence may occur in the process of multi-step cholangiocarcinogenesis, and overexpression of a polycomb group protein EZH2 may play a role in the escape from, and/or bypassing of, senescence. Furthermore, senescent cells may play important roles in tumor development and progression via the production of senescence-associated secretory phenotypes. Cellular senescence may be a new target for the prevention, early diagnosis, and therapy of cholangiocarcinoma in the near future.

Mechanical stimulation of skeletal muscle increases prostaglandin F2(alpha) synthesis and cyclooxygenase activity by a pertussis toxin sensitive mechanism

NASA Technical Reports Server (NTRS)

Vandenburgh, Herman H.; Shansky, Janet; Solerssi, Rosa; Chromiak, Joseph

1992-01-01

Repetitive mechanical stimulation of differentiated skeletal muscle in tissue culture increases the production of prostaglandin F(sub 2(alpha)), an anabolic stimulator of myofiber growth. Within 4 h of initiating mechanical activity, the activity of cyclooxygenase, a regulatory enzyme in prostaglandin synthesis, was increased 82% (P is less than .005), and this increase was maintained for at least 24 h. Kinetic analysis of the stretch-activated cyclooxygenase indicated a two to three-fold decrease in the enzyme's K(sub m) with no change in V(sub max). The stretch-induced increase in enzymatic activity was not inhibited by cycloheximide, was independent of cellular electrical activity (tetrodotoxin-insensitive), but was prevented by the G protein inhibitor pertussis toxin. Pertussis toxin also inhibited the stretch-induced increases in PGF(sub 2(alpha)) production, and cell growth. It is concluded that stretch of skeletal muscle increases the synthesis of the anabolic modulator PGF(sub 2(alpha)) by a G protein-dependent process which involves activation of cyclooxygenase by a posttranslational mechanism.

GROWTH CHARACTERISTICS OF POLIOMYELITIS VIRUS IN HELA CELL CULTURES: LACK OF PARALLELISM IN CELLULAR INJURY AND VIRUS INCREASE

PubMed Central

Ackermann, W. Wilbur; Rabson, Alan; Kurtz, Hilda

1954-01-01

A detailed study of the cytological changes which are induced in HeLa cells by the Saukett strain of Type III poliomyelitis virus has been made. The observations were of cultures in which a single sequence of infection was induced. The cytological changes were examined in relation to the growth curve of the virus in the same type of culture. This curve showed a latent period of 4 to 5 hours, followed by a gradual release of virus over an interval of 6 to 7 hours. Changes in the staining character of the cells occurred before the major portion of the viral yield appeared. The infected cells exhibited a striking cytopathology with increased basophilia, nuclear pyknosis, and basophilic cytoplasmic granules. Individual cells showed characteristic differences in the rate at which the cytopathology progresses. The multiplication of the virus in HeLa cells was inhibited by fluorophenylalanine. The inhibitory effectiveness of the antimetabolite was related to the age of the infection. It apparently inhibits only an early stage of viral development. The inhibition is completely reversed by phenylalanine if the amino acid is added within 6 hours, not later, after the induction of virostasis. The data are interpreted in terms of the rate at which the ability of the infected cell to support viral synthesis was lost. Flurophenylalanine also inhibited the multiplication of HeLa cells; however, the effect upon the uninfected cell was reversible after 3 days, as indicated by viability after such treatment. While the fluoro derivative completely inhibited viral multiplication, it did not prevent the cytopathogenic effect of the virus. In the presence of fluorophenylalanine, the disintegration of an infected cell proceeded at what appeared to be the ordinary rate, without any increase of the infectious agent. Experimentally the processes leading to viral increase and to cellular injury have been shown to possess a significant degree of autonomy. PMID:13211906

IGF-I enhances cellular senescence via the reactive oxygen species-p53 pathway

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

Handayaningsih, Anastasia-Evi; Takahashi, Michiko; Fukuoka, Hidenori

2012-08-24

Highlights: Black-Right-Pointing-Pointer Cellular senescence plays an important role in tumorigenesis and aging process. Black-Right-Pointing-Pointer We demonstrated IGF-I enhanced cellular senescence in primary confluent cells. Black-Right-Pointing-Pointer IGF-I enhanced cellular senescence in the ROS and p53-dependent manner. Black-Right-Pointing-Pointer These results may explain the underlying mechanisms of IGF-I involvement in tumorigenesis and in regulation of aging. -- Abstract: Cellular senescence is characterized by growth arrest, enlarged and flattened cell morphology, the expression of senescence-associated {beta}-galactosidase (SA-{beta}-gal), and by activation of tumor suppressor networks. Insulin-like growth factor-I (IGF-I) plays a critical role in cellular growth, proliferation, tumorigenesis, and regulation of aging. In the presentmore » study, we show that IGF-I enhances cellular senescence in mouse, rat, and human primary cells in the confluent state. IGF-I induced expression of a DNA damage marker, {gamma}H2AX, the increased levels of p53 and p21 proteins, and activated SA-{beta}-gal. In the confluent state, an altered downstream signaling of IGF-I receptor was observed. Treatment with a reactive oxygen species (ROS) scavenger, N-acetylcystein (NAC) significantly suppressed induction of these markers, indicating that ROS are involved in the induction of cellular senescence by IGF-I. In p53-null mouse embryonic fibroblasts, the IGF-I-induced augmentation of SA-{beta}-gal and p21 was inhibited, demonstrating that p53 is required for cellular senescence induced by IGF-I. Thus, these data reveal a novel pathway whereby IGF-I enhances cellular senescence in the ROS and p53-dependent manner and may explain the underlying mechanisms of IGF-I involvement in tumorigenesis and in regulation of aging.« less

Structure and functional dynamics of the mitochondrial Fe/S cluster synthesis complex.

PubMed

Boniecki, Michal T; Freibert, Sven A; Mühlenhoff, Ulrich; Lill, Roland; Cygler, Miroslaw

2017-11-03

Iron-sulfur (Fe/S) clusters are essential protein cofactors crucial for many cellular functions including DNA maintenance, protein translation, and energy conversion. De novo Fe/S cluster synthesis occurs on the mitochondrial scaffold protein ISCU and requires cysteine desulfurase NFS1, ferredoxin, frataxin, and the small factors ISD11 and ACP (acyl carrier protein). Both the mechanism of Fe/S cluster synthesis and function of ISD11-ACP are poorly understood. Here, we present crystal structures of three different NFS1-ISD11-ACP complexes with and without ISCU, and we use SAXS analyses to define the 3D architecture of the complete mitochondrial Fe/S cluster biosynthetic complex. Our structural and biochemical studies provide mechanistic insights into Fe/S cluster synthesis at the catalytic center defined by the active-site Cys of NFS1 and conserved Cys, Asp, and His residues of ISCU. We assign specific regulatory rather than catalytic roles to ISD11-ACP that link Fe/S cluster synthesis with mitochondrial lipid synthesis and cellular energy status.

Viral and Cellular mRNA Translation in Coronavirus-Infected Cells

PubMed Central

Nakagawa, K.; Lokugamage, K.G.; Makino, S.

2017-01-01

Coronaviruses have large positive-strand RNA genomes that are 5′ capped and 3′ polyadenylated. The 5′-terminal two-thirds of the genome contain two open reading frames (ORFs), 1a and 1b, that together make up the viral replicase gene and encode two large polyproteins that are processed by viral proteases into 15–16 nonstructural proteins, most of them being involved in viral RNA synthesis. ORFs located in the 3′-terminal one-third of the genome encode structural and accessory proteins and are expressed from a set of 5′ leader-containing subgenomic mRNAs that are synthesized by a process called discontinuous transcription. Coronavirus protein synthesis not only involves cap-dependent translation mechanisms but also employs regulatory mechanisms, such as ribosomal frameshifting. Coronavirus replication is known to affect cellular translation, involving activation of stress-induced signaling pathways, and employing viral proteins that affect cellular mRNA translation and RNA stability. This chapter describes our current understanding of the mechanisms involved in coronavirus mRNA translation and changes in host mRNA translation observed in coronavirus-infected cells. PMID:27712623

Cellular stress associated with the differentiation of Plasmodium berghei ookinetes.

PubMed

Duran-Bedolla, Josefina; Téllez-Sosa, Juan; Valdovinos-Torres, Humberto; Pavón, Natalia; Buelna-Chontal, Mabel; Tello-López, Angel T; Argotte-Ramos, Rocio; Rodríguez, Mario Henry; Rodríguez, María Carmen

2017-04-01

For malaria transmission, Plasmodium parasites must develop in the mosquito vector. Oxidative stress in the insect midgut, triggered by environmental changes (e.g., pH and temperature), influences the cellular signaling involved in differentiation from gametocytes to mobile ookinetes for the purpose of parasite survival. Oxidative stress activates the homeostatic response to stress characterized by the phosphorylation eIF2α, the attenuation of protein synthesis, and the transcription of genes participating in the unfolded protein response and antioxidant processes, forming a part of an integrated stress response (ISR). We hypothesized that ISR operates during the differentiation of gametocytes to ookinetes to assure Plasmodium survival. Using in-vitro conditions resembling the mosquito midgut conditions, we cultured Plasmodium berghei gametocytes to ookinetes and evaluated the redox balance by detecting reactive oxygen species and superoxide dismutase activity. Additionally, we evaluated the phosphorylation of eIF2α, the attenuation of the global protein synthesis, and the gene expression of cellular stress markers (e.g., endoplasmic reticulum chaperones and antioxidant molecules, measured by reverse-transcription quantitative polymerase chain reaction), finding that these processes were all taking place, probably to improve survival during the differentiation of Plasmodium berghei ookinetes.

Triangles bridge the scales: Quantifying cellular contributions to tissue deformation

NASA Astrophysics Data System (ADS)

Merkel, Matthias; Etournay, Raphaël; Popović, Marko; Salbreux, Guillaume; Eaton, Suzanne; Jülicher, Frank

2017-03-01

In this article, we propose a general framework to study the dynamics and topology of cellular networks that capture the geometry of cell packings in two-dimensional tissues. Such epithelia undergo large-scale deformation during morphogenesis of a multicellular organism. Large-scale deformations emerge from many individual cellular events such as cell shape changes, cell rearrangements, cell divisions, and cell extrusions. Using a triangle-based representation of cellular network geometry, we obtain an exact decomposition of large-scale material deformation. Interestingly, our approach reveals contributions of correlations between cellular rotations and elongation as well as cellular growth and elongation to tissue deformation. Using this triangle method, we discuss tissue remodeling in the developing pupal wing of the fly Drosophila melanogaster.

Physiological and Transcriptional Responses of Different Industrial Microbes at Near-Zero Specific Growth Rates.

PubMed

Ercan, Onur; Bisschops, Markus M M; Overkamp, Wout; Jørgensen, Thomas R; Ram, Arthur F; Smid, Eddy J; Pronk, Jack T; Kuipers, Oscar P; Daran-Lapujade, Pascale; Kleerebezem, Michiel

2015-09-01

The current knowledge of the physiology and gene expression of industrially relevant microorganisms is largely based on laboratory studies under conditions of rapid growth and high metabolic activity. However, in natural ecosystems and industrial processes, microbes frequently encounter severe calorie restriction. As a consequence, microbial growth rates in such settings can be extremely slow and even approach zero. Furthermore, uncoupling microbial growth from product formation, while cellular integrity and activity are maintained, offers perspectives that are economically highly interesting. Retentostat cultures have been employed to investigate microbial physiology at (near-)zero growth rates. This minireview compares information from recent physiological and gene expression studies on retentostat cultures of the industrially relevant microorganisms Lactobacillus plantarum, Lactococcus lactis, Bacillus subtilis, Saccharomyces cerevisiae, and Aspergillus niger. Shared responses of these organisms to (near-)zero growth rates include increased stress tolerance and a downregulation of genes involved in protein synthesis. Other adaptations, such as changes in morphology and (secondary) metabolite production, were species specific. This comparison underlines the industrial and scientific significance of further research on microbial (near-)zero growth physiology. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Sustainable microalgae for the simultaneous synthesis of carbon quantum dots for cellular imaging and porous carbon for CO2 capture.

PubMed

Guo, Li-Ping; Zhang, Yan; Li, Wen-Cui

2017-05-01

Microalgae biomass is a sustainable source with the potential to produce a range of products. However, there is currently a lack of practical and functional processes to enable the high-efficiency utilization of the microalgae. We report here a hydrothermal process to maximize the utilizability of microalgae biomass. Specifically, our concept involves the simultaneous conversion of microalgae to (i) hydrophilic and stable carbon quantum dots and (ii) porous carbon. The synthesis is easily scalable and eco-friendly. The microalgae-derived carbon quantum dots possess a strong two-photon fluorescence property, have a low cytotoxicity and an efficient cellular uptake, and show potential for high contrast bioimaging. The microalgae-based porous carbons show excellent CO 2 capture capacities of 6.9 and 4.2mmolg -1 at 0 and 25°C respectively, primarily due to the high micropore volume (0.59cm 3 g -1 ) and large specific surface area (1396m 2 g -1 ). Copyright © 2017 Elsevier Inc. All rights reserved.

Mechanism for CCC DNA synthesis in hepadnaviruses.

PubMed

Sohn, Ji A; Litwin, Samuel; Seeger, Christoph

2009-11-30

Hepadnavirus replication requires the synthesis of a covalently closed circular (CCC) DNA from the relaxed circular (RC) viral genome by an unknown mechanism. CCC DNA formation could require enzymatic activities of the viral reverse transcriptase (RT), or cellular DNA repair enzymes, or both. Physical mapping of the 5' and 3' ends of RC DNA and sequence analysis of CCC DNA revealed that CCC DNA synthesis requires the removal of the RT and an RNA oligomer from the 5' ends of minus and plus strand DNA, respectively, removal of sequences from the terminally redundant minus strand, completion of the less than full-length plus strand, and ligation of the ends. Two models have been proposed that could explain CCC DNA formation. The first (model 1) invokes a role for the RT to catalyze a cleavage-ligation reaction leading to the formation of a unit length minus strand in CCC DNA and a DNA repair reaction for the completion and ligation of plus strand DNA; the second (model 2) predicts that CCC DNA formation depends entirely on cellular DNA repair enzymes. To determine which mechanism is utilized, we developed cell lines expressing duck hepatitis B virus genomes carrying mutations permitting us to follow the fate of viral DNA sequences during their conversion from RC to CCC DNA. Our results demonstrated that the oligomer at the 5' end of minus strand DNA is completely or at least partially removed prior to CCC DNA synthesis. The results indicated that both RC DNA strands undergo DNA repair reactions carried out by the cellular DNA repair machinery as predicted by model 2. Thus, our study provided the basis for the identification of the cellular components required for CCC DNA formation.

Growth inhibition and possible mechanism of oleamide against the toxin-producing cyanobacterium Microcystis aeruginosa NIES-843.

PubMed

Shao, Jihai; He, Yaxian; Li, Fan; Zhang, Huiling; Chen, Anwei; Luo, Si; Gu, Ji-Dong

2016-01-01

Oleamide, a fatty acid derivative, shows inhibitory effect against the bloom-forming cyanobacterium Microcystis aeruginosa. The EC50 of oleamide on the growth of M. aeruginosa NIES-843 was 8.60 ± 1.20 mg/L. In order to elucidate the possible mechanism of toxicity of oleamide against M. aeruginosa, chlorophyll fluorescence transient, cellular ultrastructure, fatty acids composition and the transcription of the mcyB gene involved in microcystins synthesis were studied. The results of chlorophyll fluorescence transient showed that oleamide could destruct the electron accepting side of the photosystem II of M. aeruginosa NIES-843. Cellular ultrastructure examination indicated that the destruction of fatty acid constituents, the distortion of thylakoid membrane and the loss of integrity of cell membrane were associated with oleamide treatment and concentration. The damage of cellular membrane increased the release of microcystins from intact cells into the medium. Results presented in this study provide new information on the possible mechanisms involved and potential utilization of oleamide as an algicide in cyanobacterial bloom control.

Synthesis and excretion of glycerol teichoic acid during growth of two streptococcal species.

PubMed Central

Joseph, R; Shockman, G D

1975-01-01

Examination of both supernatant culture medium and cell pellets after exponential- and stationary-phase growth of Streptococcus mutans strain FA-1 and Streptococcus faecalis ATCC 9790 (S. faecium) showed the presence of [-3H]glycerol-labeled material that possessed several of the properties of glycerol teichoic acid. In the supernatant medium of S. mutans FA-1, an apparently large-molecular-size material, which eluted from agarose columns with the Kd value expected of a lipoteichoic acid, was observed. Large amounts of this material were present in supernatants during the stationary phase. In contrast, with S. faecalis only an apparently lower-molecular-weight form, with a Kd consistent with deacylated glycerol teichoic acid, was found in the growth medium. Both organisms had high-molecular-weight lipoteichoic acid in the cells along with the deacylated glycerol teichoic acid. The presence of relatively large amounts of glycerol teichoic acids in the medium was considered to be a result of excretion of these compounds rather than a result of cellular lysis. PMID:807523

Cellular Automaton Study of Hydrogen Porosity Evolution Coupled with Dendrite Growth During Solidification in the Molten Pool of Al-Cu Alloys

NASA Astrophysics Data System (ADS)

Gu, Cheng; Wei, Yanhong; Yu, Fengyi; Liu, Xiangbo; She, Lvbo

2017-09-01

Welding porosity defects significantly reduce the mechanical properties of welded joints. In this paper, the hydrogen porosity evolution coupled with dendrite growth during solidification in the molten pool of Al-4.0 wt pct Cu alloy was modeled and simulated. Three phases, including a liquid phase, a solid phase, and a gas phase, were considered in this model. The growth of dendrites and hydrogen gas pores was reproduced using a cellular automaton (CA) approach. The diffusion of solute and hydrogen was calculated using the finite difference method (FDM). Columnar and equiaxed dendrite growth with porosity evolution were simulated. Competitive growth between different dendrites and porosities was observed. Dendrite morphology was influenced by porosity formation near dendrites. After solidification, when the porosities were surrounded by dendrites, they could not escape from the liquid, and they made pores that existed in the welded joints. With the increase in the cooling rate, the average diameter of porosities decreased, and the average number of porosities increased. The average diameter of porosities and the number of porosities in the simulation results had the same trend as the experimental results.

Synthesis of nickel entities: From highly stable zerovalent nanoclusters to nanowires. Growth control and catalytic behavior.

PubMed

Peinetti, Ana S; Mizrahi, Martín; Requejo, Félix G; Buceta, David; López-Quintela, M Arturo; González, Graciela A; Battaglini, Fernando

2018-04-15

Non-noble metal nanoclusters synthesis is receiving increased attention due to their unique catalytic properties and lower cost. Herein, the synthesis of ligand-free Ni nanoclusters with an average diameter of 0.7 nm corresponding to a structure of 13 atoms is presented; they exhibit a zero-valence state and a high stability toward oxidation and thermal treatment. The nanoclusters formation method consists in the electroreduction of nickel ions inside an ordered mesoporous alumina; also, by increasing the current density, other structures can be obtained reaching to nanowires of 10 nm diameter. A seed-mediated mechanism is proposed to explain the growth to nanowires inside these mesoporous cavities. The size dependence on the catalytic behavior of these entities is illustrated by studying the reduction of methylene blue where the nanoclusters show an outstanding performance. Copyright © 2018 Elsevier Inc. All rights reserved.

Influence of Synthesis Temperature on the Growth and Surface Morphology of Co₃O₄ Nanocubes for Supercapacitor Applications.

PubMed

Samal, Rashmirekha; Dash, Barsha; Sarangi, Chinmaya Kumar; Sanjay, Kali; Subbaiah, Tondepu; Senanayake, Gamini; Minakshi, Manickam

2017-10-31

A facile hydrothermal route to control the crystal growth on the synthesis of Co₃O₄ nanostructures with cube-like morphologies has been reported and tested its suitability for supercapacitor applications. The chemical composition and morphologies of the as-prepared Co₃O₄ nanoparticles were extensively characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Varying the temperature caused considerable changes in the morphology, the electrochemical performance increased with rising temperature, and the redox reactions become more reversible. The results showed that the Co₃O₄ synthesized at a higher temperature (180 °C) demonstrated a high specific capacitance of 833 F/g. This is attributed to the optimal temperature and the controlled growth of nanocubes.

Synthesis of tritium-labeled cyadox, a promising antimicrobial growth-promoting agent with high specific activity.

PubMed

Harnud, Sechenchogt; Zhang, Aiqun; Yuan, Zonghui

2018-05-23

Cyadox is a new antimicrobial growth-promoting agent for food-producing animals. Studies on radiolabeled compounds enable the use of sensitive radiometric analytical methods and help in the elucidation of metabolic and elimination pathways. In the present study, 6-[ 3 H]-cyadox with a high specific activity of 2.08 Ci/mmol was prepared by the catalytic bromine-tritium exchange of 4-bromo-2-nitroaniline followed by a three-step microscale synthesis, giving a high yield between 36.16% and 94.75%. Copyright © 2018. Published by Elsevier Ltd.

H2‐Fueled ATP Synthesis on an Electrode: Mimicking Cellular Respiration

PubMed Central

Gutiérrez‐Sanz, Óscar; Natale, Paolo; Márquez, Ileana; Marques, Marta C.; Zacarias, Sonia; Pita, Marcos; Pereira, Inês A. C.

2016-01-01

Abstract ATP, the molecule used by living organisms to supply energy to many different metabolic processes, is synthesized mostly by the ATPase synthase using a proton or sodium gradient generated across a lipid membrane. We present evidence that a modified electrode surface integrating a NiFeSe hydrogenase and a F1F0‐ATPase in a lipid membrane can couple the electrochemical oxidation of H2 to the synthesis of ATP. This electrode‐assisted conversion of H2 gas into ATP could serve to generate this biochemical fuel locally when required in biomedical devices or enzymatic synthesis of valuable products. PMID:26991333

Disruption of methicillin-resistant Staphylococcus aureus protein synthesis by tannins

PubMed Central

Adnan, Siti-Noor-Adnalizawati; Ibrahim, Nazlina; Yaacob, Wan Ahmad

2017-01-01

Introduction Methicillin-resistant Staphylococcus aureus (MRSA) is a worldwide public health threat, displaying multiple antibiotic resistance that causes morbidity and mortality. Management of multidrug-resistant (MDR) MRSA infections is extremely difficult due to their inherent resistance to currently used antibiotics. New antibiotics are needed to combat the emergence of antimicrobial resistance. Methods The in vitro effect of tannins was studied against MRSA reference strain (ATCC 43300) and MRSA clinical strains utilizing antimicrobial assays in conjunction with both scanning and transmission electron microscopy. To reveal the influence of tannins in MRSA protein synthesis disruption, we utilized next-generation sequencing (NGS) to provide further insight into the novel protein synthesis transcriptional response of MRSA exposed to these compounds. Results Tannins possessed both bacteriostatic and bactericidal activity with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 0.78 and 1.56 mg/mL, respectively, against all tested MRSA. Scanning and transmission electron microscopy of MRSA treated with tannins showed decrease in cellular volume, indicating disruption of protein synthesis. Conclusion Analysis of a genome-wide transcriptional profile of the reference strain ATCC 43300 MRSA in response to tannins has led to the finding that tannins induced significant modulation in essential ribosome pathways, which caused a reduction in the translation processes that lead to inhibition of protein synthesis and obviation of bacterial growth. These findings highlight the potential of tannins as new promising anti-MRSA agents in clinical application such as body wash and topical cream or ointments. PMID:29264356

Modulation of growth, differentiation, and mucous glycoprotein synthesis by retinyl acetate in cloned carcinoma cell lines. [Rats

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

Marchok, A.C.; Clark, J.N.; Klein-Szanto, A.

1981-06-01

The ability of retinyl acetate to alter growth, differentiation, and synthesis of mucous glycoproteins in cell lines cloned from an adenocarcinoma (T-8) and a squamous cell carcinoma (1000 WT) was investigated with the use of F344 rats. Growth rate was inhibited approximately 25 and 50% in 6.6 x 10/sup -6/ and 3.3 x 10/sup -5/ M retinyl acetate, respectively, in both cell lines. Retinyl acetate induced the formation of numerous vacuoles and periodic acid-silver methenamine-positive granules in both T-8 and 1000 WT cells. After T-8 cells were cultured for 7 days in retinyl acetate, (/sup 3/H)glucosamine incorporation increased 133- tomore » 147-fold and (/sup 14/C)serine incorporation increased twelvefold to twentyfold in the high-molecular-weight mucous glycoprotein fraction (peak A) from the cell cytosol. In 1000 WT cells, (/sup 3/H)glucosamine incorporation increased only 4.2- to 7.5-fold, and (/sup 14/C)serine incorporation increased only 2.6- to 4.6-fold under the same culture conditions. Thus T-8 cells showed a marked increase in the synthesis and secretion of mucins, whereas 1000 WT cells showed a comparatively small but significant increase.« less

On oscillatory microstructure during cellular growth of directionally solidified Sn–36at.%Ni peritectic alloy

PubMed Central

Peng, Peng; Li, Xinzhong; Li, Jiangong; Su, Yanqing; Guo, Jingjie

2016-01-01

An oscillatory microstructure has been observed during deep-cellular growth of directionally solidified Sn–36at.%Ni hyperperitectic alloy containing intermetallic compounds with narrow solubility range. This oscillatory microstructure with a dimension of tens of micrometers has been observed for the first time. The morphology of this wave-like oscillatory structure is similar to secondary dendrite arms, and can be observed only in some local positions of the sample. Through analysis such as successive sectioning of the sample, it can be concluded that this oscillatory microstructure is caused by oscillatory convection of the mushy zone during solidification. And the influence of convection on this oscillatory microstructure was characterized through comparison between experimental and calculations results on the wavelength. Besides, the change in morphology of this oscillatory microstructure has been proved to be caused by peritectic transformation during solidification. Furthermore, the melt concentration increases continuously during solidification of intermetallic compounds with narrow solubility range, which helps formation of this oscillatory microstructure. PMID:27066761

On oscillatory microstructure during cellular growth of directionally solidified Sn-36at.%Ni peritectic alloy.

PubMed

Peng, Peng; Li, Xinzhong; Li, Jiangong; Su, Yanqing; Guo, Jingjie

2016-04-12

An oscillatory microstructure has been observed during deep-cellular growth of directionally solidified Sn-36at.%Ni hyperperitectic alloy containing intermetallic compounds with narrow solubility range. This oscillatory microstructure with a dimension of tens of micrometers has been observed for the first time. The morphology of this wave-like oscillatory structure is similar to secondary dendrite arms, and can be observed only in some local positions of the sample. Through analysis such as successive sectioning of the sample, it can be concluded that this oscillatory microstructure is caused by oscillatory convection of the mushy zone during solidification. And the influence of convection on this oscillatory microstructure was characterized through comparison between experimental and calculations results on the wavelength. Besides, the change in morphology of this oscillatory microstructure has been proved to be caused by peritectic transformation during solidification. Furthermore, the melt concentration increases continuously during solidification of intermetallic compounds with narrow solubility range, which helps formation of this oscillatory microstructure.

Structure determination and total synthesis of a novel antibacterial substance, AB0022A, produced by a cellular slime mold.

PubMed

Sawada, T; Aono, M; Asakawa, S; Ito, A; Awano, K

2000-09-01

A novel antibacterial substance, AB0022A, was isolated from the cellular slime mold Dictyostelium purpureum K1001. It inhibited the growth of Gram-positive bacteria, and its MICs ranged from 0.39 to 50 microg/ml. Because AB0022A was a highly substituted aromatic compound, we could not determine its structure based on only its physico-chemical and spectral data. We therefore used a dehalogenated derivative from AB0022A and deduced that its structure was 1,9-dihydroxy-3,7-dimethoxy-2-hexanoyl-4,6,8-trichlorodibenzofuran . To confirm this structure, we synthesized the compound having the deduced structure. The synthetic compound was identical to naturally occurring AB0022A.

Size and Morphology Controlled Synthesis of Boehmite Nanoplates and Crystal Growth Mechanisms

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

Zhang, Xin; Cui, Wenwen; Page, Katharine L.

The aluminum oxyhydroxide boehmite is an important crystalline phase in nature and industry. We report development of a flexible additive-free hydrothermal synthesis method to prepare high quality boehmite nanoplates with sizes ranging from under 20 nm to 5 um via using hydrated alumina gels and amorphous powders as precursors. The size and morphology of the boehmite nanoplates was systematically varied between hexagonal and rhombic by adjusting precursor concentrations, pH, and the synthesis temperature, due to face-specific effects. The transformation mechanism is consistent with dissolution and reprecipitation, and involves transitory initial appearance of metastable gibbsite that is later consumed upon nucleationmore » of boehmite. Detailed X-ray pair distribution characterization of the solids over time showed similarities in short-range order that suggest linkages in local chemistry and bonding topology between the precursors and product boehmite, yet also that precursor-specific differences in long-range order appear to manifest subtle changes in resulting boehmite characteristics, suggesting that the rate and extent of water release or differences in the resulting solubilized aluminate speciation leads to slightly different polymerization and condensation pathways. The findings suggest that during dissolution of the precursor that precursor-specific dehydration or solution speciation could be important aspects of the transformation impacting the molecular level details of boehmite nucleation and growth.« less

Effect of the synthesis of rice non-symbiotic hemoglobins 1 and 2 in the recombinant Escherichia coli TB1 growth

PubMed Central

Álvarez-Salgado, Emma; Arredondo-Peter, Raúl

2016-01-01

Non-symbiotic hemoglobins (nsHbs) are widely distributed in land plants, including rice. These proteins are classified into type 1 (nsHbs-1) and type 2. The O 2-affinity of nsHbs-1 is very high mostly because of an extremely low O 2-dissociation rate constant resulting in that nsHbs-1 apparently do not release O 2 after oxygenation. Thus, it is possible that the in vivo function of nsHbs-1 is other than O 2-transport. Based on the properties of multiple Hbs it was proposed that nsHbs-1 could play diverse roles in rice organs, however the in vivo activity of rice nsHbs-1 has been poorly analyzed. An in vivo analysis for rice nsHbs-1 is essential to elucidate the biological function(s) of these proteins. Rice Hb1 and Hb2 are nsHbs-1 that have been generated in recombinant Es cherichia coli TB1. The rice Hb1 and Hb2 amino acid sequence, tertiary structure and rate and equilibrium constants for the reaction of O 2 are highly similar. Thus, it is possible that rice Hb1 and Hb2 function similarly in vivo. As an initial approach to test this hypothesis we analyzed the effect of the synthesis of rice Hb1 and Hb2 in the recombinant E. coli TB1 growth. Effect of the synthesis of the O 2-carrying soybean leghemoglobin a, cowpea leghemoglobin II and Vitreoscilla Hb in the recombinant E. coli TB1 growth was also analyzed as an O 2-carrier control. Our results showed that synthesis of rice Hb1, rice Hb2, soybean Lb a, cowpea LbII and Vitreoscilla Hb inhibits the recombinant E. coli TB1 growth and that growth inhibition was stronger when recombinant E. coli TB1 synthesized rice Hb2 than when synthesized rice Hb1. These results suggested that rice Hb1 and Hb2 could function differently in vivo. PMID:26973784

Cellular uptake mediated by epidermal growth factor receptor facilitates the intracellular activity of phosphorothioate-modified antisense oligonucleotides

PubMed Central

Wang, Shiyu; Allen, Nickolas; Vickers, Timothy A; Revenko, Alexey S; Sun, Hong; Liang, Xue-hai; Crooke, Stanley T

2018-01-01

Abstract Chemically modified antisense oligonucleotides (ASOs) with phosphorothioate (PS) linkages have been extensively studied as research and therapeutic agents. PS-ASOs can enter the cell and trigger cleavage of complementary RNA by RNase H1 even in the absence of transfection reagent. A number of cell surface proteins have been identified that bind PS-ASOs and mediate their cellular uptake; however, the mechanisms that lead to productive internalization of PS-ASOs are not well understood. Here, we characterized the interaction between PS-ASOs and epidermal growth factor receptor (EGFR). We found that PS-ASOs trafficked together with EGF and EGFR into clathrin-coated pit structures. Their co-localization was also observed at early endosomes and inside enlarged late endosomes. Reduction of EGFR decreased PS-ASO activity without affecting EGF-mediated signaling pathways and overexpression of EGFR increased PS-ASO activity in cells. Furthermore, reduction of EGFR delays PS-ASO trafficking from early to late endosomes. Thus, EGFR binds to PS-ASOs at the cell surface and mediates essential steps for active (productive) cellular uptake of PS-ASOs through its cargo-dependent trafficking processes which migrate PS-ASOs from early to late endosomes. This EGFR-mediated process can also serve as an additional model to better understand the mechanism of intracellular uptake and endosomal release of PS-ASOs. PMID:29514240

Cellular pharmacodynamics of the cytotoxic guanidino-containing drug CHS 828. Comparison with methylglyoxal-bis(guanylhydrazone).

PubMed

Ekelund, S; Sjöholm, A; Nygren, P; Binderup, L; Larsson, R

2001-04-20

N-(6-(4-chlorophenoxy)hexyl)-N'-cyano-N"-4-pyridylguanidine (CHS 828) is a new guanidino-containing compound with antitumoral activity both in vitro and in vivo. Its activity profile differs from those of standard cytotoxic drugs but the mechanism of action is not yet fully understood. CHS 828 is presently in early phase I and II clinical trials. In the present study, the pharmacodynamic effects at the cellular level of CHS 828 was compared to another compound containing two guanidino groups, methylglyoxal-bis(guanylhydrazone) (MGBG). MGBG is known to inhibit the synthesis of polyamines, which are important in, e.g., proliferation and macromolecular synthesis. The concentration-response relationship of CHS 828 closely resembled that of MGBG and the drugs were similar with respect to inhibition of DNA and protein synthesis. On the other hand, CHS 828 induced a significant increase in cellular metabolism while MGBG did not. The cytotoxic effect of MGBG was reversed by the addition of exogenous polyamines, while that of CHS 828 was unaffected. Unlike MGBG, there was also no effect of CHS 828 on the levels of decarboxylating enzymes in the polyamine biosynthesis. In conclusion, CHS 828 does not appear to share any major mechanisms of action with the polyamine synthesis inhibitor MGBG. Further studies will be required to define the exact mechanism of action of CHS 828.

BTK suppresses myeloma cellular senescence through activating AKT/P27/Rb signaling.

PubMed

Gu, Chunyan; Peng, Hailin; Lu, Yue; Yang, Hongbao; Tian, Zhidan; Yin, Gang; Zhang, Wen; Lu, Sicheng; Zhang, Yi; Yang, Ye

2017-08-22

We previously explored the role of BTK in maintaining multiple myeloma stem cells (MMSCs) self-renewal and drug-resistance. Here we investigated the elevation of BTK suppressing MM cellular senescence, a state of irreversible cellular growth arrest. We firstly discovered that an increased expression of BTK in MM samples compared to normal controls by immunohistochemistry (IHC), and significant chromosomal gain in primary samples. In addition, BTK high-expressing MM patients are associated with poor outcome in both Total Therapy 2 (TT2) and TT3 cohorts. Knockdown BTK expression by shRNA induced MM cellular senescence using β-galactosidase (SA-b-gal) staining, cell growth arrest by cell cycle staining and decreased clonogenicity while forcing BTK expression in MM cells abrogated these characteristics. We also validated this feature in mouse embryonic fibroblast cells (MEFs), which showed that elevated BTK expression was resistant to MEF senescence after serial cultivation in vitro . Further mechanism study revealed that BTK activated AKT signaling leading to down-regulation of P27 expression and hindered RB activity while AKT inhibitor, LY294002, overcame BTK-overexpression induced cellular senescence resistance. Eventually we demonstrated that BTK inhibitor, CGI-1746, induced MM cellular senescence, colony reduction and tumorigenecity inhibition in vivo . Summarily, we designate a novel mechanism of BTK in mediating MM growth, and BTK inhibitor is of great potential in vivo and in vitro suggesting BTK is a promising therapeutic target for MM.

BTK suppresses myeloma cellular senescence through activating AKT/P27/Rb signaling

PubMed Central

Lu, Yue; Yang, Hongbao; Tian, Zhidan; Yin, Gang; Zhang, Wen; Lu, Sicheng; Zhang, Yi; Yang, Ye

2017-01-01

We previously explored the role of BTK in maintaining multiple myeloma stem cells (MMSCs) self-renewal and drug-resistance. Here we investigated the elevation of BTK suppressing MM cellular senescence, a state of irreversible cellular growth arrest. We firstly discovered that an increased expression of BTK in MM samples compared to normal controls by immunohistochemistry (IHC), and significant chromosomal gain in primary samples. In addition, BTK high-expressing MM patients are associated with poor outcome in both Total Therapy 2 (TT2) and TT3 cohorts. Knockdown BTK expression by shRNA induced MM cellular senescence using β-galactosidase (SA-b-gal) staining, cell growth arrest by cell cycle staining and decreased clonogenicity while forcing BTK expression in MM cells abrogated these characteristics. We also validated this feature in mouse embryonic fibroblast cells (MEFs), which showed that elevated BTK expression was resistant to MEF senescence after serial cultivation in vitro. Further mechanism study revealed that BTK activated AKT signaling leading to down-regulation of P27 expression and hindered RB activity while AKT inhibitor, LY294002, overcame BTK-overexpression induced cellular senescence resistance. Eventually we demonstrated that BTK inhibitor, CGI-1746, induced MM cellular senescence, colony reduction and tumorigenecity inhibition in vivo. Summarily, we designate a novel mechanism of BTK in mediating MM growth, and BTK inhibitor is of great potential in vivo and in vitro suggesting BTK is a promising therapeutic target for MM. PMID:28915637

Role of Fatty Acid Kinase in Cellular Lipid Homeostasis and SaeRS-Dependent Virulence Factor Expression in Staphylococcus aureus

PubMed Central

Ericson, Megan E.; Subramanian, Chitra; Frank, Matthew W.

2017-01-01

ABSTRACT The SaeRS two-component system is a master activator of virulence factor transcription in Staphylococcus aureus, but the cellular factors that control its activity are unknown. Fatty acid (FA) kinase is a two-component enzyme system required for extracellular FA uptake and SaeRS activity. Here, we demonstrate the existence of an intracellular nonesterified FA pool in S. aureus that is elevated in strains lacking FA kinase activity. SaeRS-mediated transcription is restored in FA kinase-negative strains when the intracellular FA pool is reduced either by growth with FA-depleted bovine serum albumin to extract the FA into the medium or by the heterologous expression of Neisseria gonorrhoeae acyl-acyl carrier protein synthetase to activate FA for phospholipid synthesis. These data show that FAs act as negative regulators of SaeRS signaling, and FA kinase activates SaeRS-dependent virulence factor production by lowering inhibitory FA levels. Thus, FA kinase plays a role in cellular lipid homeostasis by activating FA for incorporation into phospholipid, and it indirectly regulates SaeRS signaling by maintaining a low intracellular FA pool. PMID:28765222

Synthesis, solubilization, and surface functionalization of highly fluorescent quantum dots for cellular targeting through a small molecule

NASA Astrophysics Data System (ADS)

Galloway, Justin F.

To achieve long-term fluorescence imaging with quantum dots (QDs), a CdSe core/shell must first be synthesized. The synthesis of bright CdSe QDs is not trivial and as a consequence, the role of surfactant in nucleation and growth was investigated. It was found that the type of surfactant used, either phosphonic or fatty acid, played a pivotal role in the size of the CdSe core. The study of surfactant on CdSe synthesis, ultimately led to an electrical passivation method that utilized a short-chained phosphonic acid and highly reactive organometallic precursors to achieve high quantum yield (QY) as has been previously described. The synthesis of QDs using organometallic precursors and a phosphonic acid for passivation resulted in 4 out of 9 batches of QDs achieving QYs greater than 50% and 8 out of 9 batches with QYs greater than 35%. The synthesis of CdSe QDs was done in organic solutions rendering the surface of the particle hydrophobic. To perform cell-targeting experiments, QDs must be transferred to water. The transfer of QDs to water was successfully accomplished by using single acyl chain lipids. A systematic study of different lipid combinations and coatings demonstrated that 20-40 mol% single acyl chained lipids were able to transfer QDs to water resulting in monodispersed, stable QDs without adversely affecting the QY. The advantage to water solubilization using single acyl chain lipids is that the QD have a hydrodynamic radius less than 15 nm, QYs that can exceed 50% and additional surface functionalization can be down using the reactive sites incorporated into the lipid bilayer. QDs that are bright and stable in water were studied for the purpose of targeting G protein-coupled Receptors (GPCR). GPCRs are transmembrane receptors that internalize extracellular cues, and thus mediate signal transduction. The cyclic Adenosine Monophosphate Receptor 1 of the model organism Dictyostelium disodium was the receptor of interest. The Halo protein, a genetically

Phytochelatin synthesis and glutathione levels in response to heavy metals in tomato cells.

PubMed

Scheller, H V; Huang, B; Hatch, E; Goldsbrough, P B

1987-12-01

Cell suspension cultures of tomato, Lycopersicon esculentum Mill. cv VFNT-Cherry, produce phytochelatins (poly[gamma-glutamylcysteinyl]glycines) when exposed to cadmium. The synthesis of these peptides is accompanied by a decline in cellular levels of glutathione. Buthionine sulfoximine, an inhibitor of glutathione synthesis, inhibits the sustained production of phytochelatins. However, phytochelatin synthesis can occur in the presence of buthionine sulfoximine provided that sufficient glutathione is available. These results indicate that glutathione is a substrate for phytochelatin synthesis. The protein synthesis inhibitor cycloheximide does not affect the initial production of phytochelatin.

Further developments in the controlled growth approach for optimal structural synthesis

NASA Technical Reports Server (NTRS)

Hajela, P.

1982-01-01

It is pointed out that the use of nonlinear programming methods in conjunction with finite element and other discrete analysis techniques have provided a powerful tool in the domain of optimal structural synthesis. The present investigation is concerned with new strategies which comprise an extension to the controlled growth method considered by Hajela and Sobieski-Sobieszczanski (1981). This method proposed an approach wherein the standard nonlinear programming (NLP) methodology of working with a very large number of design variables was replaced by a sequence of smaller optimization cycles, each involving a single 'dominant' variable. The current investigation outlines some new features. Attention is given to a modified cumulative constraint representation which is defined in both the feasible and infeasible domain of the design space. Other new features are related to the evaluation of the 'effectiveness measure' on which the choice of the dominant variable and the linking strategy is based.

RRM2 induces NF-{kappa}B-dependent MMP-9 activation and enhances cellular invasiveness

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

Duxbury, Mark S.; Whang, Edward E.

2007-03-02

Ribonucleotide reductase is a dimeric enzyme that catalyzes conversion of ribonucleotide 5'-diphosphates to their 2'-deoxynucleotide forms, a rate-limiting step in the production of 2'-deoxyribonucleoside 5'-triphosphates required for DNA synthesis. The ribonucleotide reductase M2 subunit (RRM2) is a determinant of malignant cellular behavior in a range of human cancers. We examined the effect of RRM2 overexpression on pancreatic adenocarcinoma cellular invasiveness and nuclear factor-{kappa}B (NF-{kappa}B) transcription factor activity. RRM2 overexpression increases pancreatic adenocarcinoma cellular invasiveness and MMP-9 expression in a NF-{kappa}B-dependent manner. RNA interference (RNAi)-mediated silencing of RRM2 expression attenuates cellular invasiveness and NF-{kappa}B activity. NF-{kappa}B is a key mediator ofmore » the invasive phenotypic changes induced by RRM2 overexpression.« less

Plasma-assisted synthesis of MoS2

NASA Astrophysics Data System (ADS)

Campbell, Philip M.; Perini, Christopher J.; Chiu, Johannes; Gupta, Atul; Ray, Hunter S.; Chen, Hang; Wenzel, Kevin; Snyder, Eric; Wagner, Brent K.; Ready, Jud; Vogel, Eric M.

2018-03-01

There has been significant interest in transition metal dichalcogenides (TMDs), including MoS2, in recent years due to their potential application in novel electronic and optical devices. While synthesis methods have been developed for large-area films of MoS2, many of these techniques require synthesis temperatures of 800 °C or higher. As a result of the thermal budget, direct synthesis requiring high temperatures is incompatible with many integrated circuit processes as well as flexible substrates. This work explores several methods of plasma-assisted synthesis of MoS2 as a way to lower the synthesis temperature. The first approach used is conversion of a naturally oxidized molybdenum thin film to MoS2 using H2S plasma. Conversion is demonstrated at temperatures as low as 400 °C, and the conversion is enabled by hydrogen radicals which reduce the oxidized molybdenum films. The second method is a vapor phase reaction incorporating thermally evaporated MoO3 exposed to a direct H2S plasma, similar to chemical vapor deposition (CVD) synthesis of MoS2. Synthesis at 400 °C results in formation of super-stoichiometric MoS2 in a beam-interrupted growth process. A final growth method relies on a cyclical process in which a small amount of Mo is sputtered onto the substrate and is subsequently sulfurized in a H2S plasma. Similar results could be realized using an atomic layer deposition (ALD) process to deposit the Mo film. Compared to high temperature synthesis methods, the lower temperature samples are lower quality, potentially due to poor crystallinity or higher defect density in the films. Temperature-dependent conductivity measurements are consistent with hopping conduction in the plasma-assisted synthetic MoS2, suggesting a high degree of disorder in the low-temperature films. Optimization of the plasma-assisted synthesis process for slower growth rate and better stoichiometry is expected to lead to high quality films at low growth temperature.

Gravitational Effects on Cellular Flame Structure

NASA Technical Reports Server (NTRS)

Dunsky, C. M.; Fernandez-Pello, A. C.

1991-01-01

An experimental investigation has been conducted of the effect of gravity on the structure of downwardly propagating, cellular premixed propane-oxygen-nitrogen flames anchored on a water-cooled porous-plug burner. The flame is subjected to microgravity conditions in the NASA Lewis 2.2-second drop tower, and flame characteristics are recorded on high-speed film. These are compared to flames at normal gravity conditions with the same equivalence ratio, dilution index, mixture flow rate, and ambient pressure. The results show that the cellular instability band, which is located in the rich mixture region, changes little under the absence of gravity. Lifted normal-gravity flames near the cellular/lifted limits, however, are observed to become cellular when gravity is reduced. Observations of a transient cell growth period following ignition point to heat loss as being an important mechanism in the overall flame stability, dominating the stabilizing effect of buoyancy for these downwardly-propagating burner-anchored flames. The pulsations that are observed in the plume and diffusion flame generated downstream of the premixed flame in the fuel rich cases disappear in microgravity, verifying that these fluctuations are gravity related.

Investigation of growth dynamics of carbon nanotubes

PubMed Central

2017-01-01

The synthesis of single-walled carbon nanotubes (SWCNTs) with defined properties is required for both fundamental investigations and practical applications. The revealing and thorough understanding of the growth mechanism of SWCNTs is the key to the synthesis of nanotubes with required properties. This paper reviews the current status of the research on the investigation of growth dynamics of carbon nanotubes. The review starts with the consideration of the peculiarities of the growth mechanism of carbon nanotubes. The physical and chemical states of the catalyst during the nanotube growth are discussed. The chirality selective growth of nanotubes is described. The main part of the review is dedicated to the analysis and systematization of the reported results on the investigation of growth dynamics of nanotubes. The studies on the revealing of the dependence of the growth rate of nanotubes on the synthesis parameters are reviewed. The correlation between the lifetime of catalyst and growth rate of nanotubes is discussed. The reports on the calculation of the activation energy of the nanotube growth are summarized. Finally, the growth properties of inner tubes inside SWCNTs are considered. PMID:28503394

Advances in the cellular and molecular biology of angiogenesis.

PubMed

Egginton, Stuart; Bicknell, Roy

2011-12-01

Capillaries have been recognized for over a century as one of the most important components in regulating tissue oxygen transport, and their formation or angiogenesis a pivotal element of tissue remodelling during development and adaptation. Clinical interest stems from observations that both excessive and inadequate vascular growth plays a major role in human diseases, and novel developments in treatments for cancer and eye disease increasingly rely on anti-angiogenic therapies. Although the discovery of VEGF (vascular endothelial growth factor) provided the first clue for specificity of signalling in endothelial cell activation, understanding the integrative response that drives angiogenesis requires a much broader perspective. The Advances in the Cellular and Molecular Biology of Angiogenesis meeting brought together researchers at the forefront of this rapidly moving field to provide an update on current understanding, and the most recent insights into molecular and cellular mechanisms of vascular growth. The plenary lecture highlighted the integrative nature of the angiogenic process, whereas invited contributions from basic and clinician scientists described fundamental mechanisms and disease-associated issues of blood vessel formation, grouped under a number of themes to aid discussion. These articles will appeal to academic, clinical and pharmaceutical scientists interested in the molecular and cellular basis of angiogenesis, their modulation or dysfunction in human diseases, and application of these findings towards translational medicine.

Continuous transport of a small fraction of plasma membrane cholesterol to endoplasmic reticulum regulates total cellular cholesterol

PubMed Central

Infante, Rodney Elwood; Radhakrishnan, Arun

2017-01-01

Cells employ regulated transport mechanisms to ensure that their plasma membranes (PMs) are optimally supplied with cholesterol derived from uptake of low-density lipoproteins (LDL) and synthesis. To date, all inhibitors of cholesterol transport block steps in lysosomes, limiting our understanding of post-lysosomal transport steps. Here, we establish the cholesterol-binding domain 4 of anthrolysin O (ALOD4) as a reversible inhibitor of cholesterol transport from PM to endoplasmic reticulum (ER). Using ALOD4, we: (1) deplete ER cholesterol without altering PM or overall cellular cholesterol levels; (2) demonstrate that LDL-derived cholesterol travels from lysosomes first to PM to meet cholesterol needs, and subsequently from PM to regulatory domains of ER to suppress activation of SREBPs, halting cholesterol uptake and synthesis; and (3) determine that continuous PM-to-ER cholesterol transport allows ER to constantly monitor PM cholesterol levels, and respond rapidly to small declines in cellular cholesterol by activating SREBPs, increasing cholesterol uptake and synthesis. DOI: http://dx.doi.org/10.7554/eLife.25466.001 PMID:28414269

Gap junction protein expression and cellularity: comparison of immature and adult equine digital tendons

PubMed Central

Stanley, Rachael L; Fleck, Roland A; Becker, David L; Goodship, Allen E; Ralphs, Jim R; Patterson-Kane, Janet C

2007-01-01

Injury to the energy-storing superficial digital flexor tendon is common in equine athletes and is age-related. Tenocytes in the superficial digital flexor tendon of adult horses appear to have limited ability to respond adaptively to exercise or prevent the accumulation of strain-induced microdamage. It has been suggested that conditioning exercise should be introduced during the growth period, when tenocytes may be more responsive to increased quantities or intensities of mechanical strain. Tenocytes are linked into networks by gap junctions that allow coordination of synthetic activity and facilitate strain-induced collagen synthesis. We hypothesised that there are reductions in cellular expression of the gap junction proteins connexin (Cx) 43 and 32 during maturation and ageing of the superficial digital flexor tendon that do not occur in the non-injury-prone common digital extensor tendon. Cryosections from the superficial digital flexor tendon and common digital extensor tendon of 5 fetuses, 5 foals (1–6 months), 5 young adults (2–7 years) and 5 old horses (18–33 years) were immunofluorescently labelled and quantitative confocal laser microscopy was performed. Expression of Cx43 and Cx32 protein per tenocyte was significantly higher in the fetal group compared with all other age groups in both tendons. The density of tenocytes was found to be highest in immature tissue. Higher levels of cellularity and connexin protein expression in immature tendons are likely to relate to requirements for tissue remodelling and growth. However, if further studies demonstrate that this correlates with greater gap junctional communication efficiency and synthetic responsiveness to mechanical strain in immature compared with adult tendons, it could support the concept of early introduction of controlled exercise as a means of increasing resistance to later injury. PMID:17848160

Cellular telephone as reservoir of bacterial contamination: myth or fact.

PubMed

Walia, Satinder S; Manchanda, Adesh; Narang, Ramandeep S; N, Anup; Singh, Balwinder; Kahlon, Sukhdeep S

2014-01-01

To assess bacterial contamination of cellular telephone of dental care personnel, and to determine factors contributing to their contamination. A descriptive, cross-sectional study was conducted, which included 300 people using a cellular telephone The study group (hundred in each group) comprised of Dental Health Care Personnel (DHCP), In-Hospital Personnel (IHP) and Out-Hospital Personnel (OHP) of a dental college cum hospital. Swab was wiped along the front and all sides of cellular handset and it was incubated in glucose broth. The swab was subplated onto growth media plates made with half Mac Conkey's agar and half blood agar and allowed to incubate for 48 hours at 37(o)C. Isolates were tested for antimicrobial susceptibility. The analysis of presence or absence of microorganisms in the DHCP, IHP and OHP group showed no pyogenic growth in 28%, 31% and 41% cases respectively, the distribution of which was not significant (p>.05). Among non potential pathogens, spore bearing gram positive bacilli were seen in 20 cases of DHCP group, 16 cases of IHP group and 17 cases of OHP group; the distribution of which was not significant (p>.05) Among potential pathogens, significant differences were observed in the distribution of growth of Enterobacter (p<.001), Pseudomonas species (p<.05), Acinetobacter bacteria (p<.05) and Methicillin-resistant Staphylococcus aureus (MRSA) bacteria (p<.001) between the participants of different groups. RESULTs of this study showed that fomites such as cellular telephones can potentially act as "Trojan horses", thus causing Hospital-Acquired Infections (HAIs) in the dental setting.

Cell-free protein synthesis: the state of the art.

PubMed

Whittaker, James W

2013-02-01

Cell-free protein synthesis harnesses the synthetic power of biology, programming the ribosomal translational machinery of the cell to create macromolecular products. Like PCR, which uses cellular replication machinery to create a DNA amplifier, cell-free protein synthesis is emerging as a transformative technology with broad applications in protein engineering, biopharmaceutical development, and post-genomic research. By breaking free from the constraints of cell-based systems, it takes the next step towards synthetic biology. Recent advances in reconstituted cell-free protein synthesis (Protein synthesis Using Recombinant Elements expression systems) are creating new opportunities to tailor the reactions for specialized applications including in vitro protein evolution, printing protein microarrays, isotopic labeling, and incorporating nonnatural amino acids.

The Periplasmic Nitrate Reductase Nap Is Required for Anaerobic Growth and Involved in Redox Control of Magnetite Biomineralization in Magnetospirillum gryphiswaldense

PubMed Central

Li, Yingjie; Katzmann, Emanuel; Borg, Sarah

2012-01-01

The magnetosomes of many magnetotactic bacteria consist of membrane-enveloped magnetite crystals, whose synthesis is favored by a low redox potential. However, the cellular redox processes governing the biomineralization of the mixed-valence iron oxide have remained unknown. Here, we show that in the alphaproteobacterium Magnetospirillum gryphiswaldense, magnetite biomineralization is linked to dissimilatory nitrate reduction. A complete denitrification pathway, including gene functions for nitrate (nap), nitrite (nir), nitric oxide (nor), and nitrous oxide reduction (nos), was identified. Transcriptional gusA fusions as reporters revealed that except for nap, the highest expression of the denitrification genes coincided with conditions permitting maximum magnetite synthesis. Whereas microaerobic denitrification overlapped with oxygen respiration, nitrate was the only electron acceptor supporting growth in the entire absence of oxygen, and only the deletion of nap genes, encoding a periplasmic nitrate reductase, and not deletion of nor or nos genes, abolished anaerobic growth and also delayed aerobic growth in both nitrate and ammonium media. While loss of nosZ or norCB had no or relatively weak effects on magnetosome synthesis, deletion of nap severely impaired magnetite biomineralization and resulted in fewer, smaller, and irregular crystals during denitrification and also microaerobic respiration, probably by disturbing the proper redox balance required for magnetite synthesis. In contrast to the case for the wild type, biomineralization in Δnap cells was independent of the oxidation state of carbon substrates. Altogether, our data demonstrate that in addition to its essential role in anaerobic respiration, the periplasmic nitrate reductase Nap has a further key function by participating in redox reactions required for magnetite biomineralization. PMID:22730130

Knockdown of EphB1 receptor decreases medulloblastoma cell growth and migration and increases cellular radiosensitization

PubMed Central

Timofeeva, Olga; Pasquale, Elena B.; Hirsch, Kellen; MacDonald, Tobey J.; Dritschilo, Anatoly; Lee, Yi Chien; Henkemeyer, Mark; Rood, Brian; Jung, Mira; Wang, Xiao-Jing; Kool, Marcel

2015-01-01

The expression of members of the Eph family of receptor tyrosine kinases and their ephrin ligands is frequently dysregulated in medulloblastomas. We assessed the expression and functional role of EphB1 in medulloblastoma cell lines and engineered mouse models. mRNA and protein expression profiling showed expression of EphB1 receptor in the human medulloblastoma cell lines DAOY and UW228. EphB1 downregulation reduced cell growth and viability, decreased the expression of important cell cycle regulators, and increased the percentage of cells in G1 phase of the cell cycle. It also modulated the expression of proliferation, and cell survival markers. In addition, EphB1 knockdown in DAOY cells resulted in significant decrease in migration, which correlated with decreased β1-integrin expression and levels of phosphorylated Src. Furthermore, EphB1 knockdown enhanced cellular radiosensitization of medulloblastoma cells in culture and in a genetically engineered mouse medulloblastoma model. Using genetically engineered mouse models, we established that genetic loss of EphB1 resulted in a significant delay in tumor recurrence following irradiation compared to EphB1-expressing control tumors. Taken together, our findings establish that EphB1 plays a key role in medulloblastoma cell growth, viability, migration, and radiation sensitivity, making EphB1 a promising therapeutic target. PMID:25879388

Knockdown of EphB1 receptor decreases medulloblastoma cell growth and migration and increases cellular radiosensitization.

PubMed

Bhatia, Shilpa; Baig, Nimrah A; Timofeeva, Olga; Pasquale, Elena B; Hirsch, Kellen; MacDonald, Tobey J; Dritschilo, Anatoly; Lee, Yi Chien; Henkemeyer, Mark; Rood, Brian; Jung, Mira; Wang, Xiao-Jing; Kool, Marcel; Rodriguez, Olga; Albanese, Chris; Karam, Sana D

2015-04-20

The expression of members of the Eph family of receptor tyrosine kinases and their ephrin ligands is frequently dysregulated in medulloblastomas. We assessed the expression and functional role of EphB1 in medulloblastoma cell lines and engineered mouse models. mRNA and protein expression profiling showed expression of EphB1 receptor in the human medulloblastoma cell lines DAOY and UW228. EphB1 downregulation reduced cell growth and viability, decreased the expression of important cell cycle regulators, and increased the percentage of cells in G1 phase of the cell cycle. It also modulated the expression of proliferation, and cell survival markers. In addition, EphB1 knockdown in DAOY cells resulted in significant decrease in migration, which correlated with decreased β1-integrin expression and levels of phosphorylated Src. Furthermore, EphB1 knockdown enhanced cellular radiosensitization of medulloblastoma cells in culture and in a genetically engineered mouse medulloblastoma model. Using genetically engineered mouse models, we established that genetic loss of EphB1 resulted in a significant delay in tumor recurrence following irradiation compared to EphB1-expressing control tumors. Taken together, our findings establish that EphB1 plays a key role in medulloblastoma cell growth, viability, migration, and radiation sensitivity, making EphB1 a promising therapeutic target.

Cellular recovery from exposure to sub-optimal concentrations of AB toxins that inhibit protein synthesis.

PubMed

Cherubin, Patrick; Quiñones, Beatriz; Teter, Ken

2018-02-06

Ricin, Shiga toxin, exotoxin A, and diphtheria toxin are AB-type protein toxins that act within the host cytosol and kill the host cell through pathways involving the inhibition of protein synthesis. It is thought that a single molecule of cytosolic toxin is sufficient to kill the host cell. Intoxication is therefore viewed as an irreversible process. Using flow cytometry and a fluorescent reporter system to monitor protein synthesis, we show a single molecule of cytosolic toxin is not sufficient for complete inhibition of protein synthesis or cell death. Furthermore, cells can recover from intoxication: cells with a partial loss of protein synthesis will, upon removal of the toxin, increase the level of protein production and survive the toxin challenge. Thus, in contrast to the prevailing model, ongoing toxin delivery to the cytosol appears to be required for the death of cells exposed to sub-optimal toxin concentrations.

Cellular Energy Pathways as Novel Targets for the Therapy of Autosomal Dominant Polycystic Kidney Disease

DTIC Science & Technology

2017-09-01

AWARD NUMBER: W81XWH-15-1-0419 TITLE: Cellular Energy Pathways as Novel Targets for the Therapy of Autosomal Dominant Polycystic Kidney Disease...COVERED 1 Sep 2016 - 31 Aug 2017 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Cellular Energy Pathways as Novel Targets for the Therapy of Autosomal...inappropriate cell growth, fluid secretion, and dysregulation of cellular energy metabolism. The enzyme AMPK regulates a number of cellular pathways, including

Rational Targeting of Cellular Cholesterol in Diffuse Large B-Cell Lymphoma (DLBCL) Enabled by Functional Lipoprotein Nanoparticles: A Therapeutic Strategy Dependent on Cell of Origin.

PubMed

Rink, Jonathan S; Yang, Shuo; Cen, Osman; Taxter, Tim; McMahon, Kaylin M; Misener, Sol; Behdad, Amir; Longnecker, Richard; Gordon, Leo I; Thaxton, C Shad

2017-11-06

Cancer cells have altered metabolism and, in some cases, an increased demand for cholesterol. It is important to identify novel, rational treatments based on biology, and cellular cholesterol metabolism as a potential target for cancer is an innovative approach. Toward this end, we focused on diffuse large B-cell lymphoma (DLBCL) as a model because there is differential cholesterol biosynthesis driven by B-cell receptor (BCR) signaling in germinal center (GC) versus activated B-cell (ABC) DLBCL. To specifically target cellular cholesterol homeostasis, we employed high-density lipoprotein-like nanoparticles (HDL NP) that can generally reduce cellular cholesterol by targeting and blocking cholesterol uptake through the high-affinity HDL receptor, scavenger receptor type B-1 (SCARB1). As we previously reported, GC DLBCL are exquisitely sensitive to HDL NP as monotherapy, while ABC DLBCL are less sensitive. Herein, we report that enhanced BCR signaling and resultant de novo cholesterol synthesis in ABC DLBCL drastically reduces the ability of HDL NPs to reduce cellular cholesterol and induce cell death. Therefore, we combined HDL NP with the BCR signaling inhibitor ibrutinib and the SYK inhibitor R406. By targeting both cellular cholesterol uptake and BCR-associated de novo cholesterol synthesis, we achieved cellular cholesterol reduction and induced apoptosis in otherwise resistant ABC DLBCL cell lines. These results in lymphoma demonstrate that reduction of cellular cholesterol is a powerful mechanism to induce apoptosis. Cells rich in cholesterol require HDL NP therapy to reduce uptake and molecularly targeted agents that inhibit upstream pathways that stimulate de novo cholesterol synthesis, thus, providing a new paradigm for rationally targeting cholesterol metabolism as therapy for cancer.

Laminin peptide YIGSR induces collagen synthesis in Hs27 human dermal fibroblasts

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

Yoon, Jong Hyuk; Kim, Jaeyoon; Lee, Hyeongjoo

Highlights: Black-Right-Pointing-Pointer We identify a function of the YIGSR peptide to enhance collagen synthesis in Hs27. Black-Right-Pointing-Pointer YIGSR peptide enhanced collagen type 1 synthesis both of gene and protein levels. Black-Right-Pointing-Pointer There were no changes in cell proliferation and MMP-1 level in YIGSR treatment. Black-Right-Pointing-Pointer The YIGSR effect on collagen synthesis mediated activation of FAK, pyk2 and ERK. Black-Right-Pointing-Pointer The YIGSR-induced FAK and ERK activation was modulated by FAK and MEK inhibitors. -- Abstract: The dermal ECM is synthesized from fibroblasts and is primarily compromised of fibrillar collagen and elastic fibers, which support the mechanical strength and resiliency of skin,more » respectively. Laminin, a major glycoprotein located in the basement membrane, promotes cell adhesion, cell growth, differentiation, and migration. The laminin tyrosine-isoleucine-glycine-serine-arginine (YIGSR) peptide, corresponding to the 929-933 sequence of the {beta}1 chain, is known to be a functional motif with effects on the inhibition of tumor metastasis, the regulation of sensory axonal response and the inhibition of angiogenesis through high affinity to the 67 kDa laminin receptor. In this study, we identified a novel function of the YIGSR peptide to enhance collagen synthesis in human dermal fibroblasts. To elucidate this novel function regarding collagen synthesis, we treated human dermal fibroblasts with YIGSR peptide in both a time- and dose-dependent manner. According to subsequent experiments, we found that the YIGSR peptide strongly enhanced collagen type 1 synthesis without changing cell proliferation or cellular MMP-1 level. This YIGSR peptide-mediated collagen type 1 synthesis was modulated by FAK inhibitor and MEK inhibitor. This study clearly reveals that YIGSR peptide plays a novel function on the collagen type 1 synthesis of dermal fibroblasts and also suggests that YIGSR is a strong

Controlled cellular energy conversion in brown adipose tissue thermogenesis

NASA Technical Reports Server (NTRS)

Horowitz, J. M.; Plant, R. E.

1978-01-01

Brown adipose tissue serves as a model system for nonshivering thermogenesis (NST) since a) it has as a primary physiological function the conversion of chemical energy to heat; and b) preliminary data from other tissues involved in NST (e.g., muscle) indicate that parallel mechanisms may be involved. Now that biochemical pathways have been proposed for brown fat thermogenesis, cellular models consistent with a thermodynamic representation can be formulated. Stated concisely, the thermogenic mechanism in a brown fat cell can be considered as an energy converter involving a sequence of cellular events controlled by signals over the autonomic nervous system. A thermodynamic description for NST is developed in terms of a nonisothermal system under steady-state conditions using network thermodynamics. Pathways simulated include mitochondrial ATP synthesis, a Na+/K+ membrane pump, and ionic diffusion through the adipocyte membrane.

Physiological effects in bovine lymphocytes of inhibiting polyamine synthesis with ethylglyoxal bis(guanylhydrazone).

PubMed

Igarashi, K; Morris, D R

1984-11-01

Previous results have suggested that ethylglyoxal bis(guanylhydrazone) is a more specific inhibitor of polyamine biosynthesis than the widely used methylglyoxal bis(guanylhydrazone). The physiological effects on mitogenically activated lymphocytes of polyamine depletion with ethylglyoxal bis(guanylhydrazone) were examined. In the presence of ethylglyoxal bis(guanylhydrazone) and the ornithine decarboxylase inhibitor alpha-difluoromethylornithine, the cellular contents of putrescine, spermidine, and spermine were decreased by 75 to 90, 65 to 80, and 40 to 60%, respectively, compared with control cultures. Inhibition of DNA synthesis in these polyamine-deficient cells was always greater than that of protein synthesis. Upon addition of spermidine to the deficient cells, the cellular spermidine content was restored within 4 hr, but the complete recovery of macromolecular synthesis took 10 to 20 hr. Thymidine kinase and DNA polymerase alpha activities in polyamine-deficient cells were lower than those in normal cells, whereas RNA polymerase II and leucyl transfer RNA synthase activities were nearly equal to those in normal cells. These results and studies with 2-dimensional gel electrophoresis raise the possibility that polyamines may regulate the synthesis of specific proteins. Decreased synthesis of replication proteins in polyamine-deficient cells may be one reason for the reduced synthesis of DNA.

Engineering cellular fibers for musculoskeletal soft tissues using directed self-assembly.

PubMed

Schiele, Nathan R; Koppes, Ryan A; Chrisey, Douglas B; Corr, David T

2013-05-01

Engineering strategies guided by developmental biology may enhance and accelerate in vitro tissue formation for tissue engineering and regenerative medicine applications. In this study, we looked toward embryonic tendon development as a model system to guide our soft tissue engineering approach. To direct cellular self-assembly, we utilized laser micromachined, differentially adherent growth channels lined with fibronectin. The micromachined growth channels directed human dermal fibroblast cells to form single cellular fibers, without the need for a provisional three-dimensional extracellular matrix or scaffold to establish a fiber structure. Therefore, the resulting tissue structure and mechanical characteristics were determined solely by the cells. Due to the self-assembly nature of this approach, the growing fibers exhibit some key aspects of embryonic tendon development, such as high cellularity, the rapid formation (within 24 h) of a highly organized and aligned cellular structure, and the expression of cadherin-11 (indicating direct cell-to-cell adhesions). To provide a dynamic mechanical environment, we have also developed and characterized a method to apply precise cyclic tensile strain to the cellular fibers as they develop. After an initial period of cellular fiber formation (24 h postseeding), cyclic strain was applied for 48 h, in 8-h intervals, with tensile strain increasing from 0.7% to 1.0%, and at a frequency of 0.5 Hz. Dynamic loading dramatically increased cellular fiber mechanical properties with a nearly twofold increase in both the linear region stiffness and maximum load at failure, thereby demonstrating a mechanism for enhancing cellular fiber formation and mechanical properties. Tissue engineering strategies, designed to capture key aspects of embryonic development, may provide unique insight into accelerated maturation of engineered replacement tissue, and offer significant advances for regenerative medicine applications in tendon

[Effect of vesicular-arbuscular mycorrhizal fungi on growth, nutrient uptake and synthesis of volatile oil in Schizonepeta tenuifolia briq].

PubMed

Wei, G; Wang, H

1991-03-01

Inoculating Schizonepeta tenuifolia with VA mycorrhizal fungi can significantly improve the plant growth and uptake of P and S, and influence the absorption of K, Na, Fe, Mo, Mn, Zn, Co, Ba, Ni and Pb. It is interesting to note that VA mycorrhiza can also increase the synthesis of volatile oil in the shoots of S. tenuifolia. The efficiency of VA mycorrhiza varies with the fungal species.

Choroidal retinoic acid synthesis: a possible mediator between refractive error and compensatory eye growth.

PubMed

Mertz, J R; Wallman, J

2000-04-01

Research over the past two decades has shown that the growth of young eyes is guided by vision. If near- or far-sightedness is artificially imposed by spectacle lenses, eyes of primates and chicks compensate by changing their rate of elongation, thereby growing back to the pre-lens optical condition. Little is known about what chemical signals might mediate between visual effects on the retina and alterations of eye growth. We present five findings that point to choroidal retinoic acid possibly being such a mediator. First, the chick choroid can convert retinol into all-trans-retinoic acid at the rate of 11 +/- 3 pmoles mg protein(-1) hr(-1), compared to 1.3 +/- 0.3 for retina/RPE and no conversion for sclera. Second, those visual conditions that cause increased rates of ocular elongation (diffusers or negative lens wear) produce a sharp decrease in all-trans-retinoic acid synthesis to levels barely detectable with our assay. In contrast, visual conditions which result in decreased rates of ocular elongation (recovery from diffusers or positive lens wear) produce a four- to five-fold increase in the formation of all-trans-retinoic acid. Third, the choroidal retinoic acid is found bound to a 28-32 kD protein. Fourth, a large fraction of the choroidal retinoic acid synthesized in culture is found in a nucleus-enriched fraction of sclera. Finally, application of retinoic acid to cultured sclera at physiological concentrations produced an inhibition of proteoglycan production (as assessed by measuring sulfate incorporation) with a EC50 of 8 x 10(-7) M. These results show that the synthesis of choroidal retinoic acid is modulated by those visual manipulations that influence ocular elongation and that this retinoic acid may reach the sclera in concentrations adequate to modulate scleral proteoglycan formation.

Green Synthesis of Metal Nanoparticles Using Sprout Plants: Pros and Cons.

PubMed

Park, Sungmook; Sung, Hwa Kyung; Kim, Younghun

2016-05-01

A critical need in the field of nanotechnology is the development of a sustainable and eco-friendly process for the synthesis of metallic nanoparticles (NPs). To accomplish this, the use of live plants becomes essential for the production of low-cost, energy-efficient, and nontoxic metallic NPs. In this study, we tried in-vivo synthesis (green synthesis) of silver and gold NPs using seeds of bean, radish, and alfalfa, which were grown hydroponically in aqueous solutions containing metal salts, 20-25 nm sized NPs were found on the inner surfaces of the plants' vascular cylinders and cortex. The amounts of NPs taken up by the intracellular systems were clearly dependent on the exposure time and concentration of the metal salts. Although these results regarding the green synthesis of NPs on the growth of plant species are somewhat interesting and effective, metal salts adversely affected the root growth of the plants. Silver ions in the growth media showed a more negative impact on root growth compared to gold ions. Therefore, even though biosynthesis of metal NPs using live plants is considered as green synthesis, we have to consider their phytotoxicity on plant growth.

Cellular mechanisms of estradiol-mediated sexual differentiation of the brain.

PubMed

Wright, Christopher L; Schwarz, Jaclyn S; Dean, Shannon L; McCarthy, Margaret M

2010-09-01

Gonadal steroids organize the developing brain during a perinatal sensitive period and have enduring consequences for adult behavior. In male rodents testicular androgens are aromatized in neurons to estrogens and initiate multiple distinct cellular processes that ultimately determine the masculine phenotype. Within specific brain regions, overall cell number and dendritic morphology are the principal targets for hormonal organization. Recent advances have been made in elucidating the cellular mechanisms by which the neurological underpinnings of sexually dimorphic physiology and behavior are determined. These include estradiol-mediated prostaglandin synthesis, presynaptic release of glutamate, postsynaptic changes in glutamate receptors and changes in cell adhesion molecules. Sex differences in cell death are mediated by hormonal modulation of survival and death factors such as TNFalpha and Bcl-2/BAX. Copyright 2010 Elsevier Ltd. All rights reserved.

A biphasic endothelial stress-survival mechanism regulates the cellular response to vascular endothelial growth factor A

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

Latham, Antony M.; Odell, Adam F.; Mughal, Nadeem A.

2012-11-01

Vascular endothelial growth factor A (VEGF-A) is an essential cytokine that regulates endothelial function and angiogenesis. VEGF-A binding to endothelial receptor tyrosine kinases such as VEGFR1 and VEGFR2 triggers cellular responses including survival, proliferation and new blood vessel sprouting. Increased levels of a soluble VEGFR1 splice variant (sFlt-1) correlate with endothelial dysfunction in pathologies such as pre-eclampsia; however the cellular mechanism(s) underlying the regulation and function of sFlt-1 are unclear. Here, we demonstrate the existence of a biphasic stress response in endothelial cells, using serum deprivation as a model of endothelial dysfunction. The early phase is characterized by a highmore » VEGFR2:sFlt-1 ratio, which is reversed in the late phase. A functional consequence is a short-term increase in VEGF-A-stimulated intracellular signaling. In the late phase, sFlt-1 is secreted and deposited at the extracellular matrix. We hypothesized that under stress, increased endothelial sFlt-1 levels reduce VEGF-A bioavailability: VEGF-A treatment induces sFlt-1 expression at the cell surface and VEGF-A silencing inhibits sFlt-1 anchorage to the extracellular matrix. Treatment with recombinant sFlt-1 inhibits VEGF-A-stimulated in vitro angiogenesis and sFlt-1 silencing enhances this process. In this response, increased VEGFR2 levels are regulated by the phosphatidylinositol-3-kinase and PKB/Akt signaling pathways and increased sFlt-1 levels by the ERK1/2 signaling pathway. We conclude that during serum withdrawal, cellular sensing of environmental stress modulates sFlt-1 and VEGFR2 levels, regulating VEGF-A bioavailability and ensuring cell survival takes precedence over cell proliferation and migration. These findings may underpin an important mechanism contributing to endothelial dysfunction in pathological states. -- Highlights: Black-Right-Pointing-Pointer Endothelial cells mount a stress response under conditions of low serum. Black

Opposite cytokine synthesis by fibroblasts in contact co-culture with osteosarcoma cells compared with transwell co-cultures.

PubMed

David, Manu S; Kelly, Elizabeth; Zoellner, Hans

2013-04-01

We recently reported exchange of membrane and cytoplasm during contact co-culture between human Gingival Fibroblasts (h-GF) and SAOS-2 osteosarcoma cells, a process we termed 'cellular sipping' to reflect the manner in which cells become morphologically diverse through uptake of material from the opposing cell type, independent of genetic change. Cellular sipping is increased by Tumor Necrosis Factor-α (TNF-α), and we here show for the first time altered cytokine synthesis in contact co-culture supporting cellular sipping compared with co-culture where h-GF and SAOS-2 were separated in transwells. SAOS-2 had often undetectably low cytokine levels, while Interleukin-6 (IL-6), Granulocyte Colony Stimulating Factor (G-CSF) and Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF) were secreted primarily by TNF-α stimulated h-GF and basic Fibroblast Growth Factor (FGF) was prominent in h-GF lysates (p < 0.001). Contact co-cultures permitting cellular sipping had lower IL-6, G-CSF and GM-CSF levels, as well as higher lysate FGF levels compared with TNF-α treated h-GF alone (p < 0.05). The opposite was the case for co-cultures in transwells, with increased IL-6, G-CSF and GM-CSF levels (p < 0.03) and no clear difference in FGF. We thus demonstrate significant phenotypic change in cultures where cellular sipping occurs, potentially contributing to tumor inflammatory responses. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

Cellular Contraction and Polarization Drive Collective Cellular Motion.

PubMed

Notbohm, Jacob; Banerjee, Shiladitya; Utuje, Kazage J C; Gweon, Bomi; Jang, Hwanseok; Park, Yongdoo; Shin, Jennifer; Butler, James P; Fredberg, Jeffrey J; Marchetti, M Cristina

2016-06-21

Coordinated motions of close-packed multicellular systems typically generate cooperative packs, swirls, and clusters. These cooperative motions are driven by active cellular forces, but the physical nature of these forces and how they generate collective cellular motion remain poorly understood. Here, we study forces and motions in a confined epithelial monolayer and make two experimental observations: 1) the direction of local cellular motion deviates systematically from the direction of the local traction exerted by each cell upon its substrate; and 2) oscillating waves of cellular motion arise spontaneously. Based on these observations, we propose a theory that connects forces and motions using two internal state variables, one of which generates an effective cellular polarization, and the other, through contractile forces, an effective cellular inertia. In agreement with theoretical predictions, drugs that inhibit contractility reduce both the cellular effective elastic modulus and the frequency of oscillations. Together, theory and experiment provide evidence suggesting that collective cellular motion is driven by at least two internal variables that serve to sustain waves and to polarize local cellular traction in a direction that deviates systematically from local cellular velocity. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Postischemic revascularization: from cellular and molecular mechanisms to clinical applications.

PubMed

Silvestre, Jean-Sébastien; Smadja, David M; Lévy, Bernard I

2013-10-01

After the onset of ischemia, cardiac or skeletal muscle undergoes a continuum of molecular, cellular, and extracellular responses that determine the function and the remodeling of the ischemic tissue. Hypoxia-related pathways, immunoinflammatory balance, circulating or local vascular progenitor cells, as well as changes in hemodynamical forces within vascular wall trigger all the processes regulating vascular homeostasis, including vasculogenesis, angiogenesis, arteriogenesis, and collateral growth, which act in concert to establish a functional vascular network in ischemic zones. In patients with ischemic diseases, most of the cellular (mainly those involving bone marrow-derived cells and local stem/progenitor cells) and molecular mechanisms involved in the activation of vessel growth and vascular remodeling are markedly impaired by the deleterious microenvironment characterized by fibrosis, inflammation, hypoperfusion, and inhibition of endogenous angiogenic and regenerative programs. Furthermore, cardiovascular risk factors, including diabetes, hypercholesterolemia, hypertension, diabetes, and aging, constitute a deleterious macroenvironment that participates to the abrogation of postischemic revascularization and tissue regeneration observed in these patient populations. Thus stimulation of vessel growth and/or remodeling has emerged as a new therapeutic option in patients with ischemic diseases. Many strategies of therapeutic revascularization, based on the administration of growth factors or stem/progenitor cells from diverse sources, have been proposed and are currently tested in patients with peripheral arterial disease or cardiac diseases. This review provides an overview from our current knowledge regarding molecular and cellular mechanisms involved in postischemic revascularization, as well as advances in the clinical application of such strategies of therapeutic revascularization.

[Effects of germanium on cell growth, polysaccharide production and cellular redox status in suspension cultures of protocorm-like bodies of Dendrobium huoshanense].

PubMed

Wei, Ming; Yang, Chaoying; Jiang, Shaotong

2010-03-01

To solve the problem of low growth rate and metabolism level in suspension cultures of protocorm-like bodies (PLBs) of Dendrobium huoshanense. The effects of germanium on PLB proliferation and accumulation of polysaccharides together with nutrient utilization were investigated and the contents of reducing sugars, soluble proteins, the activities of antioxidant enzymes and redox status of the cells of PLB were analyzed. The results indicated that the optimum concentration of germanium dioxide (4.0 mg/L) significantly enhanced the cell growth and accumulation of polysaccharides, greatly improved contents of reducing sugars and soluble proteins, increased the activities of superoxide dismutase (SOD) and catalase (CAT) but decreased the activity of peroxidase(POD). The cell dry weight and production of polysaccharides were 32.6 g/L and 3.78 g/L, respectively. The analysis of cellular redox status showed that the ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG) in cells and the activity of glutathione reductase were significantly increased by the addition of germanium dioxide. The suitable concentration of germanium dioxide was beneficial to the cell growth and the accumulation of polysaccharides.

Efficient delivery to human lung fibroblasts (WI-38) of pirfenidone incorporated into liposomes modified with truncated basic fibroblast growth factor and its inhibitory effect on collagen synthesis in idiopathic pulmonary fibrosis.

PubMed

Togami, Kohei; Miyao, Aki; Miyakoshi, Kei; Kanehira, Yukimune; Tada, Hitoshi; Chono, Sumio

2015-01-01

In the present in vitro study, we assessed the delivery of pirfenidone incorporated into liposomes modified with truncated basic fibroblast growth factor (tbFGF) to lung fibroblasts and investigated the anti-fibrotic effect of the drug. The tbFGF peptide, KRTGQYKLC, was used to modify the surface of liposomes (tbFGF-liposomes). We used the thin-layer evaporation method, followed by sonication, to prepare tbFGF-liposomes containing pirfenidone. The cellular accumulation of tbFGF-liposomes was 1.7-fold greater than that of non-modified liposomes in WI-38 cells used as a model of lung fibroblasts. Confocal laser scanning microscopy showed that tbFGF-liposomes were widely localized in WI-38 cells. The inhibitory effects of pirfenidone incorporated into tbFGF-liposomes on transforming growth factor-β1 (TGF-β1)-induced collagen synthesis in WI-38 cells were evaluated by measuring the level of intracellular hydroxyproline, a major component of the protein collagen. Pirfenidone incorporated into tbFGF-liposomes at concentrations of 10, 30, and 100 µM significantly decreased the TGF-β1-induced hydroxyproline content in WI-38 cells. The anti-fibrotic effect of pirfenidone incorporated into tbFGF-liposomes was enhanced compared with that of pirfenidone solution. These results indicate that tbFGF-liposomes are a useful drug delivery system of anti-fibrotic drugs to lung fibroblasts for the treatment of idiopathic pulmonary fibrosis.

Tinkering with Translation: Protein Synthesis in Virus-Infected Cells

PubMed Central

Walsh, Derek; Mathews, Michael B.; Mohr, Ian

2013-01-01

Viruses are obligate intracellular parasites, and their replication requires host cell functions. Although the size, composition, complexity, and functions encoded by their genomes are remarkably diverse, all viruses rely absolutely on the protein synthesis machinery of their host cells. Lacking their own translational apparatus, they must recruit cellular ribosomes in order to translate viral mRNAs and produce the protein products required for their replication. In addition, there are other constraints on viral protein production. Crucially, host innate defenses and stress responses capable of inactivating the translation machinery must be effectively neutralized. Furthermore, the limited coding capacity of the viral genome needs to be used optimally. These demands have resulted in complex interactions between virus and host that exploit ostensibly virus-specific mechanisms and, at the same time, illuminate the functioning of the cellular protein synthesis apparatus. PMID:23209131

A Herpesvirus Ribosome-Associated, RNA-Binding Protein Confers a Growth Advantage upon Mutants Deficient in a GADD34-Related Function†

PubMed Central

Mulvey, Matthew; Poppers, Jeremy; Ladd, Alison; Mohr, Ian

1999-01-01

The herpes simplex virus type 1 γ34.5 gene product and the cellular GADD34 protein both contain similar domains that can regulate the activity of eukaryotic initiation factor 2 (eIF2), a critical translation initiation factor. Viral mutants that lack the GADD34-related function grow poorly on a variety of malignant human cells, as activation of the cellular PKR kinase leads to the accumulation of inactive, phosphorylated eIF2 at late times postinfection. Termination of translation prior to the completion of the viral reproductive cycle leads to impaired growth. Extragenic suppressors that regain the ability to synthesize proteins efficiently in the absence of the viral GADD34-related function have been isolated. These suppressor alleles are dominant in trans and affect the steady-state accumulation of several viral mRNA species. We demonstrate that deregulated expression of Us11, a virus-encoded RNA-binding, ribosome-associated protein is necessary and sufficient to confer a growth advantage upon viral mutants that lack a GADD34-related function. Ectopic expression of Us11 reduces the accumulation of the activated cellular PKR kinase and allows for sustained protein synthesis. Thus, an RNA-binding, ribosome-associated protein (Us11) and a GADD34-related protein (γ34.5) both function in a signal pathway that regulates translation by modulating eIF2 phosphorylation. PMID:10074192

Cellular Telephone as Reservoir of Bacterial Contamination: Myth or Fact

PubMed Central

Walia, Satinder S.; Manchanda, Adesh; Narang, Ramandeep S.; N., Anup; Singh, Balwinder; Kahlon, Sukhdeep S.

2014-01-01

Objective: To assess bacterial contamination of cellular telephone of dental care personnel, and to determine factors contributing to their contamination. Materials and Methods: A descriptive, cross-sectional study was conducted, which included 300 people using a cellular telephone The study group (hundred in each group) comprised of Dental Health Care Personnel (DHCP), In-Hospital Personnel (IHP) and Out-Hospital Personnel (OHP) of a dental college cum hospital. Swab was wiped along the front and all sides of cellular handset and it was incubated in glucose broth. The swab was subplated onto growth media plates made with half Mac Conkey’s agar and half blood agar and allowed to incubate for 48 hours at 37oC. Isolates were tested for antimicrobial susceptibility. Result: The analysis of presence or absence of microorganisms in the DHCP, IHP and OHP group showed no pyogenic growth in 28%, 31% and 41% cases respectively, the distribution of which was not significant (p>.05). Among non potential pathogens, spore bearing gram positive bacilli were seen in 20 cases of DHCP group, 16 cases of IHP group and 17 cases of OHP group; the distribution of which was not significant (p>.05) Among potential pathogens, significant differences were observed in the distribution of growth of Enterobacter (p<.001), Pseudomonas species (p<.05), Acinetobacter bacteria (p<.05) and Methicillin-resistant Staphylococcus aureus (MRSA) bacteria (p<.001) between the participants of different groups. Conclusion: Results of this study showed that fomites such as cellular telephones can potentially act as “Trojan horses”, thus causing Hospital-Acquired Infections (HAIs) in the dental setting. PMID:24596722

Phenotypic Screening Identifies Protein Synthesis Inhibitors as H-Ras-Nanocluster-Increasing Tumor Growth Inducers.

PubMed

Najumudeen, Arafath K; Posada, Itziar M D; Lectez, Benoit; Zhou, Yong; Landor, Sebastian K-J; Fallarero, Adyary; Vuorela, Pia; Hancock, John; Abankwa, Daniel

2015-12-15

Ras isoforms H-, N-, and K-ras are each mutated in specific cancer types at varying frequencies and have different activities in cell fate control. On the plasma membrane, Ras proteins are laterally segregated into isoform-specific nanoscale signaling hubs, termed nanoclusters. As Ras nanoclusters are required for Ras signaling, chemical modulators of nanoclusters represent ideal candidates for the specific modulation of Ras activity in cancer drug development. We therefore conducted a chemical screen with commercial and in-house natural product libraries using a cell-based H-ras-nanoclustering FRET assay. Next to established Ras inhibitors, such as a statin and farnesyl-transferase inhibitor, we surprisingly identified five protein synthesis inhibitors as positive regulators. Using commonly employed cycloheximide as a representative compound, we show that protein synthesis inhibition increased nanoclustering and effector recruitment specifically of active H-ras but not of K-ras. Consistent with these data, cycloheximide treatment activated both Erk and Akt kinases and specifically promoted H-rasG12V-induced, but not K-rasG12V-induced, PC12 cell differentiation. Intriguingly, cycloheximide increased the number of mammospheres, which are enriched for cancer stem cells. Depletion of H-ras in combination with cycloheximide significantly reduced mammosphere formation, suggesting an exquisite synthetic lethality. The potential of cycloheximide to promote tumor cell growth was also reflected in its ability to increase breast cancer cell tumors grown in ovo. These results illustrate the possibility of identifying Ras-isoform-specific modulators using nanocluster-directed screening. They also suggest an unexpected feedback from protein synthesis inhibition to Ras signaling, which might present a vulnerability in certain tumor cell types.

Flotillin proteins recruit sphingosine to membranes and maintain cellular sphingosine-1-phosphate levels

PubMed Central

Riento, Kirsi; Zhang, Qifeng; Clark, Jonathan; Begum, Farida; Stephens, Elaine; Wakelam, Michael J.

2018-01-01

Sphingosine-1-phosphate (S1P) is an important lipid signalling molecule. S1P is produced via intracellular phosphorylation of sphingosine (Sph). As a lipid with a single fatty alkyl chain, Sph may diffuse rapidly between cellular membranes and through the aqueous phase. Here, we show that the absence of microdomains generated by multimeric assemblies of flotillin proteins results in reduced S1P levels. Cellular phenotypes of flotillin knockout mice, including changes in histone acetylation and expression of Isg15, are recapitulated when S1P synthesis is perturbed. Flotillins bind to Sph in vitro and increase recruitment of Sph to membranes in cells. Ectopic re-localisation of flotillins within the cell causes concomitant redistribution of Sph. The data suggest that flotillins may directly or indirectly regulate cellular sphingolipid distribution and signalling. PMID:29787576

Organizing principles underlying microorganism's growth-robustness trade-off.

PubMed

Bolli, Alessandro; Salvador, Armindo

2014-10-01

Growth Robustness Reciprocity (GRR) is an intriguing microbial manifestation: the impairment of microorganism's growth enhances their ability to resist acute stresses, and vice-versa. This is caused by regulatory interactions that determine higher expression of protection mechanisms in response to low growth rates. But because such regulatory mechanisms are species-specific, GRR must result from convergent evolution. Why does natural selection favor such an outcome? We used mathematical models of optimal cellular resource allocation to identify the general principles underlying GRR. Non-linear optimization allowed to predict allocation patterns of biosynthetic resources (ribosomes devoted to the synthesis of each cell component) that maximize growth. These models predict the down-regulation of stress defenses under high substrate availabilities and low stress levels. Under these conditions, stress tolerance ensues from growth-related damage dilution: the higher the substrate availability, the fastest the dilution of damaged proteins by newly synthesized proteins, the lower the accumulation of damaged components into the cell. In turn, under low substrate availability growth is too slow for effective damage dilution, and the expression of the defenses up to some optimal level then increases growth. As a consequence, slow-growing cells are pre-adapted to withstand acute stresses. Therefore, the observed negative correlation between growth and stress tolerance can be explained as a consequence of optimal resource allocation for maximal growth. We acknowledge fellowship SFRH/BPD/90065/2012 and grants PEst-C/SAU/LA0001/2013-2014 and FCOMP-01-0124-FEDER-020978 financed by FEDER through the "Programa Operacional Factores de Competitividade, COMPETE" and by national funds through "FCT, Fundação para a Ciência e a Tecnologia" (project PTDC/QUI-BIQ/119657/2010). Copyright © 2014. Published by Elsevier Inc.

CELLULAR DIFFERENTIATION AND THE AGING PROCESS IN CARTILAGINOUS TISSUES

PubMed Central

Shulman, Herbert J.; Meyer, Karl

1968-01-01

Primary cell cultures of differentiated chondrocytes were shown to produce chondroitin-4-sulfate as the predominant mucopolysaccharide, with suggestive evidence for the synthesis of keratan sulfate and possibly chondroitin-6-sulfate. Chicken embryonic cartilage was shown to be composed mainly of chondroitin-4-sulfate, with a small amount of chondroitin-6-sulfate, but essentially no keratan sulfate. These findings were compared to the data of others, and a hypothesis explaining the aging process in cartilage in terms of cellular differentiation was presented. PMID:5688079

Synthesis, characterisation, and in vitro cellular uptake kinetics of nanoprecipitated poly(2-methacryloyloxyethyl phosphorylcholine)- b-poly(2-(diisopropylamino)ethyl methacrylate) (MPC-DPA) polymeric nanoparticle micelles for nanomedicine applications

NASA Astrophysics Data System (ADS)

Salvage, Jonathan P.; Smith, Tia; Lu, Tao; Sanghera, Amendeep; Standen, Guy; Tang, Yiqing; Lewis, Andrew L.

2016-10-01

Nanoscience offers the potential for great advances in medical technology and therapies in the form of nanomedicine. As such, developing controllable, predictable, and effective, nanoparticle-based therapeutic systems remains a significant challenge. Many polymer-based nanoparticle systems have been reported to date, but few harness materials with accepted biocompatibility. Phosphorylcholine (PC) based biomimetic materials have a long history of successful translation into effective commercial medical technologies. This study investigated the synthesis, characterisation, nanoprecipitation, and in vitro cellular uptake kinetics of PC-based polymeric nanoparticle micelles (PNM) formed by the biocompatible and pH responsive block copolymer poly(2-methacryloyloxyethyl phosphorylcholine)- b-poly(2-(diisopropylamino)ethyl methacrylate) (MPC-DPA). Atom transfer radical polymerisation (ATRP), and gel permeation chromatography (GPC) were used to synthesise and characterise the well-defined MPC100-DPA100 polymer, revealing organic GPC, using evaporative light scatter detection, to be more accurate than aqueous GPC for this application. Subsequent nanoprecipitation investigations utilising photon correlation spectroscopy (PCS) revealed PNM size increased with polymer concentration, and conferred Cryo-stability. PNM diameters ranged from circa 64-69 nm, and increased upon hydrophobic compound loading, circa 65-71 nm, with loading efficiencies of circa 60 % achieved, whilst remaining monodisperse. In vitro studies demonstrated that the PNM were of low cellular toxicity, with colony formation and MTT assays, utilising V79 and 3T3 cells, yielding comparable results. Investigation of the in vitro cellular uptake kinetics revealed rapid, 1 h, cellular uptake of MPC100-DPA100 PNM delivered fluorescent probes, with fluorescence persistence for 48 h. This paper presents the first report of these novel findings, which highlight the potential of the system for nanomedicine application

Evaluation of cellular glasses for solar mirror panel applications

NASA Technical Reports Server (NTRS)

Giovan, M.; Adams, M.

1979-01-01

An analytic technique was developed to compare the structural and environmental performance of various materials considered for backing of second surface glass solar mirrors. Cellular glass was determined to be a prime candidate due to its low cost, high stiffness-to-weight ratio, thermal expansion match to mirror glass, evident minimal environmental impact and chemical and dimensional stability under conditions of use. The current state of the art and anticipated developments in cellular glass technology are discussed; material properties are correlated to design requirements. A mathematical model is presented which suggests a design approach which allows minimization of life cost; and, a mechanical and environmental testing program is outlined, designed to provide a material property basis for development of cellular glass hardware, together with methodology for collecting lifetime predictive data. Preliminary material property data from measurements are given. Microstructure of several cellular materials is shown, and sensitivity of cellular glass to freeze-thaw degradation and to slow crack growth is discussed. The effect of surface coating is addressed.

Longevity of major coenzymes allows minimal de novo synthesis in microorganisms.

PubMed

Hartl, Johannes; Kiefer, Patrick; Meyer, Fabian; Vorholt, Julia A

2017-05-15

Coenzymes are vital for cellular metabolism and act on the full spectrum of enzymatic reactions. Intrinsic chemical reactivity, enzyme promiscuity and high flux through their catalytic cycles make coenzymes prone to damage. To counteract such compromising factors and ensure stable levels of functional coenzymes, cells use a complex interplay between de novo synthesis, salvage, repair and degradation. However, the relative contribution of these factors is currently unknown, as is the overall stability of coenzymes in the cell. Here, we use dynamic 13 C-labelling experiments to determine the half-life of major coenzymes of Escherichia coli. We find that coenzymes such as pyridoxal 5-phosphate, flavins, nicotinamide adenine dinucleotide (phosphate) and coenzyme A are remarkably stable in vivo and allow biosynthesis close to the minimal necessary rate. In consequence, they are essentially produced to compensate for dilution by growth and passed on over generations of cells. Exceptions are antioxidants, which are short-lived, suggesting an inherent requirement for increased renewal. Although the growth-driven turnover of stable coenzymes is apparently subject to highly efficient end-product homeostasis, we exemplify that coenzyme pools are propagated in excess in relation to actual growth requirements. Additional testing of Bacillus subtilis and Saccharomyces cerevisiae suggests that coenzyme longevity is a conserved feature in biology.

Physiological epidermal growth factor concentrations activate high affinity receptors to elicit calcium oscillations.

PubMed

Marquèze-Pouey, Béatrice; Mailfert, Sébastien; Rouger, Vincent; Goaillard, Jean-Marc; Marguet, Didier

2014-01-01

Signaling mediated by the epidermal growth factor (EGF) is crucial in tissue development, homeostasis and tumorigenesis. EGF is mitogenic at picomolar concentrations and is known to bind its receptor on high affinity binding sites depending of the oligomerization state of the receptor (monomer or dimer). In spite of these observations, the cellular response induced by EGF has been mainly characterized for nanomolar concentrations of the growth factor, and a clear definition of the cellular response to circulating (picomolar) concentrations is still lacking. We investigated Ca2+ signaling, an early event in EGF responses, in response to picomolar doses in COS-7 cells where the monomer/dimer equilibrium is unaltered by the synthesis of exogenous EGFR. Using the fluo5F Ca2+ indicator, we found that picomolar concentrations of EGF induced in 50% of the cells a robust oscillatory Ca2+ signal quantitatively similar to the Ca2+ signal induced by nanomolar concentrations. However, responses to nanomolar and picomolar concentrations differed in their underlying mechanisms as the picomolar EGF response involved essentially plasma membrane Ca2+ channels that are not activated by internal Ca2+ store depletion, while the nanomolar EGF response involved internal Ca2+ release. Moreover, while the picomolar EGF response was modulated by charybdotoxin-sensitive K+ channels, the nanomolar response was insensitive to the blockade of these ion channels.

Suppressing the cellular breakdown in silicon supersaturated with titanium

NASA Astrophysics Data System (ADS)

Liu, Fang; Prucnal, S.; Hübner, R.; Yuan, Ye; Skorupa, W.; Helm, M.; Zhou, Shengqiang

2016-06-01

Hyper doping Si with up to 6 at.% Ti in solid solution was performed by ion implantation followed by pulsed laser annealing and flash lamp annealing. In both cases, the implanted Si layer can be well recrystallized by liquid phase epitaxy and solid phase epitaxy, respectively. Cross-sectional transmission electron microscopy of Ti-implanted Si after liquid phase epitaxy shows the so-called growth interface breakdown or cellular breakdown owing to the occurrence of constitutional supercooling in the melt. The appearance of cellular breakdown prevents further recrystallization. However, the out-diffusion and cellular breakdown can be effectively suppressed by solid phase epitaxy during flash lamp annealing due to the high velocity of amorphous-crystalline interface and the low diffusion velocity for Ti in the solid phase.

Size-tailored synthesis of silver quasi-nanospheres by kinetically controlled seeded growth.

PubMed

Liu, Xiaxia; Yin, Yadong; Gao, Chuanbo

2013-08-20

This paper describes a simple and convenient procedure to synthesize monodisperse silver (Ag) quasi-nanospheres with size tunable in a range of 19-140 nm through a one-step seeded growth strategy. Acetonitrile was employed as a coordinating ligand of a Ag(I) salt in order to achieve a low concentration of elemental Ag after reduction and thus suppression of new nucleation events. Since the addition of the seeds significantly accelerates the reduction reaction of Ag(I) by ascorbic acid, the reaction kinetics was further delicately balanced by tuning the reaction temperature, which proved to be critical in producing Ag quasi-nanospheres with uniform size and shape. This synthesis is highly scalable, so that it provides a simple yet very robust process for producing Ag quasi-nanospheres for many biological, analytical, and catalytic applications which often demand samples in large quantity and widely tunable particle sizes.

Glutamine drives glutathione synthesis and contributes to radiation sensitivity of A549 and H460 lung cancer cell lines

PubMed Central

Sappington, Daniel R.; Siegel, Eric R.; Hiatt, Gloria; Desai, Abhishek; Penney, Rosalind B.; Jamshidi-Parsian, Azemat; Griffin, Robert J.; Boysen, Gunnar

2016-01-01

Background Increased glutamine uptake is known to drive cancer cell proliferation, making tumor cells glutamine-dependent. Glutamine provides additional carbon and nitrogen sources for cell growth. The first step in glutamine utilization is its conversion to glutamate by glutaminase (GLS). Glutamate is a precursor for glutathione synthesis, and we investigated the hypothesis that glutamine drives glutathione synthesis and thereby contributes to cellular defense systems. Methods The importance of glutamine for glutathione synthesis was studied in H460 and A549 lung cancer cell lines using glutamine-free medium and Bis-2-(5-phenyl-acetamido-1,3,4-thiadiazol-2-yl)ethyl sulfide (BPTES) a GLS inhibitor. Metabolic activities were determined by targeted mass spectrometry. Results A significant correlation between glutamine consumption and glutathione excretion was demonstrated in H460 and A549 tumor cells. Culturing in the presence of [13C5]glutamine demonstrated that by 12 hrs >50% of excreted glutathione is derived from glutamine. Culturing in glutamine-free medium or treatment with BPTES, a glutaminase (GLS)-specific inhibitor, reduced cell proliferation and viability, and abolished glutathione excretion. Treatment with glutathione-ester prevented BPTES induced cytotoxicity. Inhibition of GLS markedly radiosensitized the lung tumor cell lines, suggesting an important role of glutamine-derived glutathione in determining radiation sensitivity. Conclusions We demonstrate here for the first time that a significant amount of extracellular glutathione is directly derived from glutamine. This finding adds yet another important function to the already known glutamine dependence of tumor cells and probably tumors as well. General significance Glutamine is essential for synthesis and excretion of glutathione to promote cell growth and viability. PMID:26825773

Sterol synthesis and cell size distribution under oscillatory growth conditions in Saccharomyces cerevisiae scale-down cultivations.

PubMed

Marbà-Ardébol, Anna-Maria; Bockisch, Anika; Neubauer, Peter; Junne, Stefan

2018-02-01

Physiological responses of yeast to oscillatory environments as they appear in the liquid phase in large-scale bioreactors have been the subject of past studies. So far, however, the impact on the sterol content and intracellular regulation remains to be investigated. Since oxygen is a cofactor in several reaction steps within sterol metabolism, changes in oxygen availability, as occurs in production-scale aerated bioreactors, might have an influence on the regulation and incorporation of free sterols into the cell lipid layer. Therefore, sterol and fatty acid synthesis in two- and three-compartment scale-down Saccharomyces cerevisiae cultivation were studied and compared with typical values obtained in homogeneous lab-scale cultivations. While cells were exposed to oscillating substrate and oxygen availability in the scale-down cultivations, growth was reduced and accumulation of carboxylic acids was increased. Sterol synthesis was elevated to ergosterol at the same time. The higher fluxes led to increased concentrations of esterified sterols. The cells thus seem to utilize the increased availability of precursors to fill their sterol reservoirs; however, this seems to be limited in the three-compartment reactor cultivation due to a prolonged exposure to oxygen limitation. Besides, a larger heterogeneity within the single-cell size distribution was observed under oscillatory growth conditions with three-dimensional holographic microscopy. Hence the impact of gradients is also observable at the morphological level. The consideration of such a single-cell-based analysis provides useful information about the homogeneity of responses among the population. Copyright © 2017 John Wiley & Sons, Ltd.

A genetically encoded fluorescent tRNA is active in live-cell protein synthesis

PubMed Central

Masuda, Isao; Igarashi, Takao; Sakaguchi, Reiko; Nitharwal, Ram G.; Takase, Ryuichi; Han, Kyu Young; Leslie, Benjamin J.; Liu, Cuiping; Gamper, Howard; Ha, Taekjip; Sanyal, Suparna

2017-01-01

Abstract Transfer RNAs (tRNAs) perform essential tasks for all living cells. They are major components of the ribosomal machinery for protein synthesis and they also serve in non-ribosomal pathways for regulation and signaling metabolism. We describe the development of a genetically encoded fluorescent tRNA fusion with the potential for imaging in live Escherichia coli cells. This tRNA fusion carries a Spinach aptamer that becomes fluorescent upon binding of a cell-permeable and non-toxic fluorophore. We show that, despite having a structural framework significantly larger than any natural tRNA species, this fusion is a viable probe for monitoring tRNA stability in a cellular quality control mechanism that degrades structurally damaged tRNA. Importantly, this fusion is active in E. coli live-cell protein synthesis allowing peptidyl transfer at a rate sufficient to support cell growth, indicating that it is accommodated by translating ribosomes. Imaging analysis shows that this fusion and ribosomes are both excluded from the nucleoid, indicating that the fusion and ribosomes are in the cytosol together possibly engaged in protein synthesis. This fusion methodology has the potential for developing new tools for live-cell imaging of tRNA with the unique advantage of both stoichiometric labeling and broader application to all cells amenable to genetic engineering. PMID:27956502

Origins of the protein synthesis cycle

NASA Technical Reports Server (NTRS)

Fox, S. W.

1981-01-01

Largely derived from experiments in molecular evolution, a theory of protein synthesis cycles has been constructed. The sequence begins with ordered thermal proteins resulting from the self-sequencing of mixed amino acids. Ordered thermal proteins then aggregate to cell-like structures. When they contained proteinoids sufficiently rich in lysine, the structures were able to synthesize offspring peptides. Since lysine-rich proteinoid (LRP) also catalyzes the polymerization of nucleoside triphosphate to polynucleotides, the same microspheres containing LRP could have synthesized both original cellular proteins and cellular nucleic acids. The LRP within protocells would have provided proximity advantageous for the origin and evolution of the genetic code.

Cellular interface morphologies in directional solidification. II - The effect of grain boundaries

NASA Technical Reports Server (NTRS)

Ungar, Lyle H.; Brown, Robert A.

1984-01-01

A singular perturbation analysis valid for small grain-boundary slopes is used with the one-sided model for solidification to show that grain boundaries introduce imperfections into the symmetry of the developing cellular interfaces which rupture the junction between the family of planar shapes and the bifurcating cellular families. Undulating interfaces are shown to develop first near grain boundaries, and to evolve with decreasing temperature gradient either by a smooth transition from the almost planar family or by a sudden jump to moderate-amplitude cellular forms, depending on the growth rate.

Synthesis and single crystal growth of perovskite semiconductor CsPbBr3

NASA Astrophysics Data System (ADS)

Zhang, Mingzhi; Zheng, Zhiping; Fu, Qiuyun; Chen, Zheng; He, Jianle; Zhang, Sen; Chen, Cheng; Luo, Wei

2018-02-01

As a typical representative of all-inorganic lead halide perovskites, cesium lead bromine (CsPbBr3) has attracted significant attention in recent years. The direct band gap semiconductor CsPbBr3 has a wide band gap of 2.25 eV and high average atomic number (Cs: 55, Pb: 82 and Br: 35), which meet most of the requirements for detection of X- and γ-ray radiation, such as high attenuation, high resistivity, and significant photoconductivity response. However, the growth of large volume CsPbBr3 single crystals remains a challenge. In this paper, the synthesis of CsPbBr3 polycrystalline powders by a chemical co-precipitation method was investigated and the optimum synthesis conditions were obtained. A large CsPbBr3 single crystal of 8 mm diameter and 60 mm length was obtained by a creative electronic dynamic gradient (EDG) method. X-ray diffraction (XRD) patterns and X-ray rocking curve showed that the CsPbBr3 crystal preferentially oriented in the (1 1 0) direction and had a low dislocation density and small residual stress in the crystal. The IR and UV-Vis transmittance and temperature-dependent photoluminescence (PL) spectra showed the crystal had a good basic optical performance. The almost linear current-voltage (I-V) curves implied good ohmic contact between the electrodes and crystal surfaces. The resistivity of the crystal was calculated 109-1010 Ω cm. The above results showed that the quality of the obtained crystal had met the demand of optoelectronic applications.

Rosiglitazone ameliorates senescence-like phenotypes in a cellular photoaging model.

PubMed

Chen, Liang; Bi, Bo; Zeng, Jiping; Zhou, Yiqun; Yang, Ping; Guo, Yu; Zhu, Jingjing; Yang, Qingjian; Zhu, Ningwen; Liu, Tianyi

2015-03-01

Rosiglitazone (RO), a second-generation thiazolidinedione used mainly in the treatment of non-insulin-dependent diabetes mellitus, has been discovered to be a high-affinity ligand for peroxisome proliferator-activated receptor-γ (PPAR-γ). Several studies have revealed that PPAR-γ is also involved in the regulation of oxidative stress and chronic inflammation associated with aging process in vivo as well as with cellular senescence in vitro. We sought to investigate whether RO pretreatment will counteract the photoaging process using a well-established cellular photoaging model. Murine dermal fibroblasts (MDFs) were cultured in the absence or presence of RO for 48h, followed by exposure to repeated UVB irradiation. The senescent phenotypes were evaluated including cell viability, senescence-associated β-galactosidase (SA-β-gal) expression, cell morphology, ROS generation, cell cycle, production and degradation of extracellular matrix (ECM), and the potential mechanisms were discussed. Pretreatment with RO (40μM) significantly decreased the staining intensity and the percentage of SA-β-gal-positive cells and reserved the elongated cell shape compared with UVB group. The cells pretreated with RO also showed decreased UVB-induced degradation of type I collagen by decreasing MMPs expressions. In addition, we observed counteraction of cell-cycle arrest and repression of UVB-induced p53 and p21 in the presence of RO. We further confirmed a significant decrease in ROS accumulation accompanied by an increase in catalase in RO group. RO, a potent PPAR-γ activator, counteracts senescence-like phenotypes, including long-term growth arrest, flattened morphology, degradation of ECM and SA-β-gal-positive staining in MDFs by inhibiting the expression of MMPs and increasing the synthesis of catalase when administered to repeated UVB irradiation. The novel application of RO may lead to innovative and effective anti-photoaging therapies. Copyright © 2015 Japanese Society

Cellular and multicellular form and function.

PubMed

Liu, Wendy F; Chen, Christopher S

2007-11-10

Engineering artificial tissue constructs requires the appropriate spatial arrangement of cells within scaffolds. The introduction of microengineering tools to the biological community has provided a valuable set of techniques to manipulate the cellular environment, and to examine how cell structure affects cellular function. Using micropatterning techniques, investigators have found that the geometric presentation of cell-matrix adhesions are important regulators of various cell behaviors including cell growth, proliferation, differentiation, polarity and migration. Furthermore, the presence of neighboring cells in multicellular aggregates has a significant impact on the proliferative and differentiated state of cells. Using microengineering tools, it will now be possible to manipulate the various environmental factors for practical applications such as engineering tissue constructs with greater control over the physical structure and spatial arrangement of cells within their surrounding microenvironment.

Experiment K-7-22: Growth Hormone Regulation Synthesis and Secretion in Microgravity. Part 2; Hypothalamic Growth Hormone-Releasing Factor, Somatostatin Immunoreactivity, and Messenger RNA Levels in Microgravity

NASA Technical Reports Server (NTRS)

Sawchenko, P. E.; Arias, C.; Krasnov, I.; Grindeland, R. E.; Vale, W.

1994-01-01

Immunohistochemical analyses of hypothalamic hormones carried out on tissue from rats flown on an earlier flight (Cosmos 1887) suggested preferential effects on hypophysiotropic principles involved in the regulation of growth hormone secretion and synthesis. We found that staining in the median eminence for peptides that provide both stimulatory (growth hormone-releasing factor, or GRF) and inhibitory (somatostatin, SS) influences on growth hormone secretion were depressed in flight animals relative to synchronous controls, while staining for other neuroendocrine peptides, cortocotropin-releasing factor and arginine vasopressin, were similar in these two groups. While this suggests some selective impact of weightlessness on the two principal central nervous system regulators of growth hormone dynamics, the fact that both GRF- and SS-immunoreactivity (IR) appeared affected in the same direction is somewhat problematic, and makes tentative any intimation that effects on CNS control mechanisms may be etiologically significant contributors to the sequelae of reduced growth hormone secretion seen in prolonged space flight. To provide an additional, and more penetrating, analysis we attempted in hypothalamic material harvested from animals flown on Cosmos 2044 to complement immunohistochemical analyses of GRF and SS staining with quantitative, in situ assessments of messenger RNAs encoding the precursors for both these hormones.

Heat shock represses rRNA synthesis by inactivation of TIF-IA and lncRNA-dependent changes in nucleosome positioning.

PubMed

Zhao, Zhongliang; Dammert, Marcel A; Hoppe, Sven; Bierhoff, Holger; Grummt, Ingrid

2016-09-30

Attenuation of ribosome biogenesis in suboptimal growth environments is crucial for cellular homeostasis and genetic integrity. Here, we show that shutdown of rRNA synthesis in response to elevated temperature is brought about by mechanisms that target both the RNA polymerase I (Pol I) transcription machinery and the epigenetic signature of the rDNA promoter. Upon heat shock, the basal transcription factor TIF-IA is inactivated by inhibition of CK2-dependent phosphorylations at Ser170/172. Attenuation of pre-rRNA synthesis in response to heat stress is accompanied by upregulation of PAPAS, a long non-coding RNA (lncRNA) that is transcribed in antisense orientation to pre-rRNA. PAPAS interacts with CHD4, the adenosine triphosphatase subunit of NuRD, leading to deacetylation of histones and movement of the promoter-bound nucleosome into a position that is refractory to transcription initiation. The results exemplify how stress-induced inactivation of TIF-IA and lncRNA-dependent changes of chromatin structure ensure repression of rRNA synthesis in response to thermo-stress. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

Synthesis, purification and bulk crystal growth of radiation detector materials using melt growth technique

NASA Astrophysics Data System (ADS)

Surabhi, Raja Rahul Reddy

In the past decade, there has been new and increased usage of radiation-detection technologies for applications in homeland security, non-proliferation, and national defense. Most of these applications require a portable device with high gamma-ray energy resolution and detection efficiency, compact size, room-temperature operation, and low cost. Consequently, there is a renewed understanding of the material limitations for these technologies and a great demand to develop next-generation radiation-detection materials that can operate at room temperature. Mercuric iodide (HgI2), Lead iodide (PbI2), and CdZnTe (CZT) are the current leading candidates for radiation detector applications. This is because of their high atomic number and large band gap that makes them particularly well suited for fabrication of high resolution and high efficiency compact devices. PbI2 is a promising material for room temperature nuclear radiation detectors, characterized by its wide band gap (EG=2.32eV) and high-density (rho=6.2g/cm3). It has been reported that PbI2 crystal detectors are able to detect gamma-ray in the range of 1KeV-1MeV, with good energy resolution. However, PbI 2 detectors have not been studied in detail because of non-availability of high quality single crystals. This study presents the synthesis, purification, growth and characterization of PbI2 single crystals grown. In this research, solid-state synthesis technique has been utilized for obtaining PbI2 as a starting material. For the first time, a unique low-temperature purification technique has been developed to obtain high-purity starting material. The crystals were grown using 2-zone Bridgman-Stockbarger (B.S) technique wherein growth rate and temperature gradient at the solid-liquid interface were optimized. Single crystals of PbI2 were successfully grown in quartz glass ampoule under different growth conditions. Material purity was determined by measuring the elemental concentration using the Inductively

Growth hormone stimulation test - series (image)

MedlinePlus

... skeletal growth in children. In adults, GH stimulates protein synthesis in muscle and the release of fatty acids ... acids. The amino acids are used in the synthesis of proteins, and the muscle shifts to using fatty acids ...

Viral and cellular subnuclear structures in human cytomegalovirus-infected cells.

PubMed

Strang, Blair L

2015-02-01

In human cytomegalovirus (HCMV)-infected cells, a dramatic remodelling of the nuclear architecture is linked to the creation, utilization and manipulation of subnuclear structures. This review outlines the involvement of several viral and cellular subnuclear structures in areas of HCMV replication and virus-host interaction that include viral transcription, viral DNA synthesis and the production of DNA-filled viral capsids. The structures discussed include those that promote or impede HCMV replication (such as viral replication compartments and promyelocytic leukaemia nuclear bodies, respectively) and those whose role in the infected cell is unclear (for example, nucleoli and nuclear speckles). Viral and cellular proteins associated with subnuclear structures are also discussed. The data reviewed here highlight advances in our understanding of HCMV biology and emphasize the complexity of HCMV replication and virus-host interactions in the nucleus. © 2015 The Authors.

Fibronectin gene expression, synthesis and accumulation during in vitro differentiation of chicken osteoblasts

NASA Technical Reports Server (NTRS)

Winnard, R. G.; Gerstenfeld, L. C.; Toma, C. D.; Franceschi, R. T.; Landis, W. J. (Principal Investigator)

1995-01-01

A well-defined chicken osteoblast culture system(18) has been used to examine fibronectin (FN) mRNA levels, synthesis, and accumulation during in vitro differentiation and matrix mineralization. Immunofluorescent staining of cells after 6 or 18 days in culture revealed that FN was initially associated with the cell surface and in partial coalignment with cytoskeletal elements while at the latter time most FN was associated with the extracellular matrix as a ubiquitous fibrillar network. Western blot analysis of total cell-associated proteins also detected FN at all culture times. However, when results were normalized to cellular DNA, FN levels increased until 12-16 and remained relatively constant thereafter. Similarly, FN synthesis as measured by [35S]-methionine labeling, and immunoprecipitation was greatest in early cultures (culture day 3) and then declined such that synthesis decreased 60% at day 18 and 94% after 24-31 days. FN mRNA levels as measured by Northern blot analysis were well correlated with FN synthesis. These results clearly show that FN is made by primary osteoblasts during their in vitro maturation. In contrast to other osteoblast markers such as alkaline phosphatase, osteocalcin, and osteopontin, whose expression increases as cells differentiate, FN accumulates in the matrix during periods of early cell growth and attachment and then remains proportional to cell number. Results with FN differ from those obtained with collagen which continues to accumulate in the extracellular matrix during osteoblast maturation. These results are consistent with FN being important for the initial attachment of early osteoblasts or osteoblast precursors to the pericellular matrix.

Nitric oxide synthesis leads to vascular endothelial growth factor synthesis via the NO/cyclic guanosine 3',5'-monophosphate (cGMP) pathway in human corpus cavernosal smooth muscle cells.

PubMed

Komori, Kazuhiko; Tsujimura, Akira; Takao, Tetsuya; Matsuoka, Yasuhiro; Miyagawa, Yasushi; Takada, Shingo; Nonomura, Norio; Okuyama, Akihiko

2008-07-01

Vascular smooth muscle cells express endothelial nitric oxide synthase (eNOS) and produce nitric oxide (NO). Recently, increased NO production has been reported to induce the synthesis and secretion of vascular endothelial growth factor (VEGF) via the NO/cyclic guanosine 3',5'-monophosphate (cGMP) pathway. L-arginine (L-arg), the precursor of NO, and selective phosphodiesterase type 5 (PDE-5) inhibitors that increase levels of intracellular cGMP may complementarily enhance VEGF synthesis in corpus cavernosal smooth muscle cells (CCSMCs), and may consequently restore impaired endothelial function. Expression of eNOS in corpus cavernosal smooth muscle has also been reported. However, it is unclear whether CCSMCs can generate NO. To elucidate whether CCSMCs can synthesize NO and whether NO synthesis enhances VEGF synthesis via the NO/cGMP pathway. Corpus cavernosal cells were cultured and characterized by immunocytochemistry and immunoblotting. CCSMCs were treated with L-arg. CCSMCs were also incubated with L-arg and with vardenafil, an inhibitor of PDE-5. Release of NO from cells was confirmed by assay of NO metabolites (NOx). Intracellular cGMP concentration and VEGF concentration in the medium were measured. Isolated cells were determined to be CCSMCs. The expression of eNOS by CCSMCs was also identified. NOx and cGMP levels in the L-arg-treated group were significantly greater than those in the control group. VEGF and cGMP levels in the L-arg-treated group were also significantly greater than those in the control group. VEGF and cGMP levels in the L-arg + vardenafil-treated group were significantly greater than those in the L-arg-treated group and the control group. CCSMCs express eNOS and synthesize NO. NO synthesis leads to enhancement of VEGF synthesis via the NO/cGMP pathway. Combined L-arg and vardenafil treatment, which can enhance VEGF production, may provide a novel therapeutic strategy for the treatment of erectile dysfunction as well as endothelial

A Rapid Method for Quantifying Viable Mycobacterium avium subsp. paratuberculosis in Cellular Infection Assays

PubMed Central

Pooley, Hannah B.; de Silva, Kumudika; Purdie, Auriol C.; Begg, Douglas J.; Whittington, Richard J.

2016-01-01

ABSTRACT Determining the viability of bacteria is a key outcome of in vitro cellular infection assays. Currently, this is done by culture, which is problematic for fastidious slow-growing bacteria such as Mycobacterium avium subsp. paratuberculosis, where it can take up to 4 months to confirm growth. This study aimed to identify an assay that can rapidly quantify the number of viable M. avium subsp. paratuberculosis cells in a cellular sample. Three commercially available bacterial viability assays along with a modified liquid culture method coupled with high-throughput quantitative PCR growth detection were assessed. Criteria for assessment included the ability of each assay to differentiate live and dead M. avium subsp. paratuberculosis organisms and their accuracy at low bacterial concentrations. Using the culture-based method, M. avium subsp. paratuberculosis growth was reliably detected and quantified within 2 weeks. There was a strong linear association between the 2-week growth rate and the initial inoculum concentration. The number of viable M. avium subsp. paratuberculosis cells in an unknown sample was quantified based on the growth rate, by using growth standards. In contrast, none of the commercially available viability assays were suitable for use with samples from in vitro cellular infection assays. IMPORTANCE Rapid quantification of the viability of Mycobacterium avium subsp. paratuberculosis in samples from in vitro cellular infection assays is important, as it allows these assays to be carried out on a large scale. In vitro cellular infection assays can function as a preliminary screening tool, for vaccine development or antimicrobial screening, and also to extend findings derived from experimental animal trials. Currently, by using culture, it takes up to 4 months to obtain quantifiable results regarding M. avium subsp. paratuberculosis viability after an in vitro infection assay; however, with the quantitative PCR and liquid culture method

Developing Inhibitors of Translesion DNA Synthesis as Therapeutic Agents against Lung Cancer

DTIC Science & Technology

2015-12-01

normal DNA synthesis. In contrast, pol eta shows a combination of high efficiency and low fidelity when replicating 8-oxo-G. These combined properties...are consistent with a pro- mutagenic role for pol eta when replicating this DNA lesion under cellular conditions. Studies with modified nucleotide...analogs indicate that pol eta relies heavily on hydrogen-bonding interactions during normal and translesion synthesis. However, some nucleobase

Compatible Solute Synthesis and Import by the Moderate Halophile Spiribacter salinus: Physiology and Genomics

PubMed Central

León, María J.; Hoffmann, Tamara; Sánchez-Porro, Cristina; Heider, Johann; Ventosa, Antonio; Bremer, Erhard

2018-01-01

Members of the genus Spiribacter are found worldwide and are abundant in ecosystems possessing intermediate salinities between seawater and saturated salt concentrations. Spiribacter salinus M19-40 is the type species of this genus and its first cultivated representative. In the habitats of S. salinus M19-40, high salinity is a key determinant for growth and we therefore focused on the cellular adjustment strategy to this persistent environmental challenge. We coupled these experimental studies to the in silico mining of the genome sequence of this moderate halophile with respect to systems allowing this bacterium to control its potassium and sodium pools, and its ability to import and synthesize compatible solutes. S. salinus M19-40 produces enhanced levels of the compatible solute ectoine, both under optimal and growth-challenging salt concentrations, but the genes encoding the corresponding biosynthetic enzymes are not organized in a canonical ectABC operon. Instead, they are scrambled (ectAC; ectB) and are physically separated from each other on the S. salinus M19-40 genome. Genomes of many phylogenetically related bacteria also exhibit a non-canonical organization of the ect genes. S. salinus M19-40 also synthesizes trehalose, but this compatible solute seems to make only a minor contribution to the cytoplasmic solute pool under osmotic stress conditions. However, its cellular levels increase substantially in stationary phase cells grown under optimal salt concentrations. In silico genome mining revealed that S. salinus M19-40 possesses different types of uptake systems for compatible solutes. Among the set of compatible solutes tested in an osmostress protection growth assay, glycine betaine and arsenobetaine were the most effective. Transport studies with radiolabeled glycine betaine showed that S. salinus M19-40 increases the pool size of this osmolyte in a fashion that is sensitively tied to the prevalent salinity of the growth medium. It was amassed in

The Presence of ADP-Ribosylated Fe Protein of Nitrogenase in Rhodobacter capsulatus Is Correlated with Cellular Nitrogen Status

PubMed Central

Yakunin, Alexander F.; Laurinavichene, Tatyana V.; Tsygankov, Anatoly A.; Hallenbeck, Patrick C.

1999-01-01

The photosynthetic bacterium Rhodobacter capsulatus has been shown to regulate its nitrogenase by covalent modification via the reversible ADP-ribosylation of Fe protein in response to darkness or the addition of external NH4+. Here we demonstrate the presence of ADP-ribosylated Fe protein under a variety of steady-state growth conditions. We examined the modification of Fe protein and nitrogenase activity under three different growth conditions that establish different levels of cellular nitrogen: batch growth with limiting NH4+, where the nitrogen status is externally controlled; batch growth on relatively poor nitrogen sources, where the nitrogen status is internally controlled by assimilatory processes; and continuous culture. When cultures were grown to stationary phase with different limiting concentrations of NH4+, the ADP-ribosylation state of Fe protein was found to correlate with cellular nitrogen status. Additionally, actively growing cultures (grown with N2 or glutamate), which had an intermediate cellular nitrogen status, contained a portion of their Fe protein in the modified state. The correlation between cellular nitrogen status and ADP-ribosylation state was corroborated with continuous cultures grown under various degrees of nitrogen limitation. These results show that in R. capsulatus the modification system that ADP-ribosylates nitrogenase in the short term in response to abrupt changes in the environment is also capable of modifying nitrogenase in accordance with long-term cellular conditions. PMID:10094674

Hypoxic and Ras-transformed cells support growth by scavenging unsaturated fatty acids from lysophospholipids

PubMed Central

Kamphorst, Jurre J.; Cross, Justin R.; Fan, Jing; de Stanchina, Elisa; Mathew, Robin; White, Eileen P.; Thompson, Craig B.; Rabinowitz, Joshua D.

2013-01-01

Cancer cell growth requires fatty acids to replicate cellular membranes. The kinase Akt is known to up-regulate fatty acid synthesis and desaturation, which is carried out by the oxygen-consuming enzyme stearoyl-CoA desaturase (SCD)1. We used 13C tracers and lipidomics to probe fatty acid metabolism, including desaturation, as a function of oncogene expression and oxygen availability. During hypoxia, flux from glucose to acetyl-CoA decreases, and the fractional contribution of glutamine to fatty acid synthesis increases. In addition, we find that hypoxic cells bypass de novo lipogenesis, and thus, both the need for acetyl-CoA and the oxygen-dependent SCD1-reaction, by scavenging serum fatty acids. The preferred substrates for scavenging are phospholipids with one fatty acid tail (lysophospholipids). Hypoxic reprogramming of de novo lipogenesis can be reproduced in normoxic cells by Ras activation. This renders Ras-driven cells, both in culture and in allografts, resistant to SCD1 inhibition. Thus, a mechanism by which oncogenic Ras confers metabolic robustness is through lipid scavenging. PMID:23671091

TEMPERATURE-SENSITIVE DEXTRANSUCRASE SYNTHESIS BY A LACTOBACILLUS.

PubMed

DUNICAN, L K; SEELEY, H W

1963-11-01

Dunican, L. K. (Cornell University, Ithaca, New York), and H. W. Seeley, Jr. Temperature-sensitive dextransucrase synthesis by a lactobacillus. J. Bacteriol. 86:1079-1083. 1963.-Dextran synthesis was found to be temperature-dependent in Lactobacillus strain RWM-13. Dextran was not formed above 37 C, although growth of cells occurred up to 42 C. Logarithmically growing cells transferred from 30 C to 40 C ceased producing dextran while growth decreased nominally. An examination of the extracts of cells broken by sonic treatment showed that as the temperature of growth was increased above 37 C the production of dextransucrase decreased. By use of an inhibitor of invertase, 10(-4)m AgNO(3), it was shown that invertase replaced dextransucrase activity at temperatures above 37 C. In contrast to dextransucrase in Leuconostoc mesenteroides, the enzyme in Lactobacillus strain RWM-13 was constitutive and thus resembled that of Streptococcus bovis. Thermosensitivity of dextransucrase synthesis has not been observed in Leuconostoc or Streptococcus.

Endocrinological control of growth.

PubMed

Sizonenko, P C

1978-01-01

Many endocrinological factors control cellular growth of different tissues (cell multiplication and cell volume) and skeletal growth. The role of neuro-transmitters and of hypothalamic releasing and inhibiting factors of growth hormone secretion will be reviewed. The importance of the somatomedins on cartilage growth will be stressed. Thyroid hormones, androgens, and oestrogens have important stimulating actions on skeletal growth and maturation. Conversely, glucocorticoids have an important inhibitory effect on growth. The precise roles of these hormone factors in the regulation of growth hormone secretion, somatomedin production and tissue growth, particularly the cartilage, remain to be completely elucidated.

Inhibition of NFkappaB reduces cellular viability in GH3 pituitary adenoma cells.

PubMed

Vender, John R; Laird, Melissa D; Dhandapani, Krishnan M

2008-05-01

Adenomas of the pituitary gland are among the most common types of tumors of the adult brain. Although adenomas are histologically benign, they may be associated with significant morbidity and mortality, mostly because of their invasive growth pattern and hormone hypersecretion. Current medical therapies are suppressive, acting at a receptor level. Thus, there is a need to identify novel cellular and molecular targets for pituitary tumors. We investigated the possible role of the NFkappaB transcription factor in pituitary tumor cell growth. The effect of NFkappaB pathway inhibition on cellular viability was studied in the GH3 pituitary adenoma cell line, a well-characterized rat cell line that secretes growth hormone and prolactin. Cells were treated with mechanistically diverse pharmacological NFkappaB pathway inhibitors or with molecular inhibitors that were overexpressed in tumor cells before the assessment of cellular viability. NFkappaB activity was also assessed in GH3 cells using deoxyribonucleic acid binding assays. GH3 cells exhibited constitutive NFkappaB activity, which contributed to increased cellular proliferation. Treatment with wedelolactone, an IkappaB kinase inhibitor, or overexpression of an IkappaB super-repressor reduced cell viability, further implicating NFkappaB in pituitary tumor cell growth. Pharmacological or molecular inhibition of Akt similarly reduced GH3 viability and NFkappaB binding, suggesting that constitutive activation of NFkappaB may be, at least in part, mediated by Akt. Directed targeting of the Akt and NFkappaB signaling pathways may be a useful adjunct in the clinical management of pituitary tumors. Further elucidation of this pathway may yield novel information regarding the behavior of pituitary tumors in humans.

Polyamines in chemiosmosis in vivo: A cunning mechanism for the regulation of ATP synthesis during growth and stress

PubMed Central

Ioannidis, Nikolaos E.; Kotzabasis, Kiriakos

2014-01-01

Polyamines (PAs) are low molecular weight amines that occur in every living organism. The three main PAs (putrescine, spermidine, and spermine) are involved in several important biochemical processes covered in recent reviews. As rule of thumb, increase of the cellular titer of PAs in plants is related to cell growth and cell tolerance to abiotic and biotic stress. In the present contribution, we describe recent findings from plant bioenergetics that bring to light a previously unrecognized dynamic behavior of the PA pool. Traditionally, PAs are described by many authors as organic polycations, when in fact they are bases that can be found in a charged or uncharged form. Although uncharged forms represent less than 0.1% of the total pool, we propose that their physiological role could be crucial in chemiosmosis. This process describes the formation of a PA gradient across membranes within seconds and is difficult to be tested in vivo in plants due to the relatively small molecular weight of PAs and the speed of the process. We tested the hypothesis that PAs act as permeable buffers in intact leaves by using recent advances in vivo probing. We found that an increase of PAs increases the electric component (Δψ) and decreases the ΔpH component of the proton motive force. These findings reveal an important modulation of the energy production process and photoprotection of the chloroplast by PAs. We explain in detail the theory behind PA pumping and ion trapping in acidic compartments (such as the lumen in chloroplasts) and how this regulatory process could improve either the photochemical efficiency of the photosynthetic apparatus and increase the synthesis of ATP or fine tune antenna regulation and make the plant more tolerant to stress. PMID:24592272

Oscillatory cellular patterns in three-dimensional directional solidification

NASA Astrophysics Data System (ADS)

Tourret, D.; Debierre, J.-M.; Song, Y.; Mota, F. L.; Bergeon, N.; Guérin, R.; Trivedi, R.; Billia, B.; Karma, A.

2015-10-01

We present a phase-field study of oscillatory breathing modes observed during the solidification of three-dimensional cellular arrays in microgravity. Directional solidification experiments conducted onboard the International Space Station have allowed us to observe spatially extended homogeneous arrays of cells and dendrites while minimizing the amount of gravity-induced convection in the liquid. In situ observations of transparent alloys have revealed the existence, over a narrow range of control parameters, of oscillations in cellular arrays with a period ranging from about 25 to 125 min. Cellular patterns are spatially disordered, and the oscillations of individual cells are spatiotemporally uncorrelated at long distance. However, in regions displaying short-range spatial ordering, groups of cells can synchronize into oscillatory breathing modes. Quantitative phase-field simulations show that the oscillatory behavior of cells in this regime is linked to a stability limit of the spacing in hexagonal cellular array structures. For relatively high cellular front undercooling (i.e., low growth velocity or high thermal gradient), a gap appears in the otherwise continuous range of stable array spacings. Close to this gap, a sustained oscillatory regime appears with a period that compares quantitatively well with experiment. For control parameters where this gap exists, oscillations typically occur for spacings at the edge of the gap. However, after a change of growth conditions, oscillations can also occur for nearby values of control parameters where this gap just closes and a continuous range of spacings exists. In addition, sustained oscillations at to the opening of this stable gap exhibit a slow periodic modulation of the phase-shift among cells with a slower period of several hours. While long-range coherence of breathing modes can be achieved in simulations for a perfect spatial arrangement of cells as initial condition, global disorder is observed in both

A cellular automaton - finite volume method for the simulation of dendritic and eutectic growth in binary alloys using an adaptive mesh refinement

NASA Astrophysics Data System (ADS)

Dobravec, Tadej; Mavrič, Boštjan; Šarler, Božidar

2017-11-01

A two-dimensional model to simulate the dendritic and eutectic growth in binary alloys is developed. A cellular automaton method is adopted to track the movement of the solid-liquid interface. The diffusion equation is solved in the solid and liquid phases by using an explicit finite volume method. The computational domain is divided into square cells that can be hierarchically refined or coarsened using an adaptive mesh based on the quadtree algorithm. Such a mesh refines the regions of the domain near the solid-liquid interface, where the highest concentration gradients are observed. In the regions where the lowest concentration gradients are observed the cells are coarsened. The originality of the work is in the novel, adaptive approach to the efficient and accurate solution of the posed multiscale problem. The model is verified and assessed by comparison with the analytical results of the Lipton-Glicksman-Kurz model for the steady growth of a dendrite tip and the Jackson-Hunt model for regular eutectic growth. Several examples of typical microstructures are simulated and the features of the method as well as further developments are discussed.

Some growth factors stimulate cultured adult rabbit ventricular myocyte hypertrophy in the absence of mechanical loading

NASA Technical Reports Server (NTRS)

Decker, R. S.; Cook, M. G.; Behnke-Barclay, M.; Decker, M. L.

1995-01-01

Cultured adult rabbit cardiac myocytes treated with recombinant growth factors display enhanced rates of protein accumulation (ie, growth) in response to insulin and insulin-like growth factors (IGFs), but epidermal growth factor, acidic or basic fibroblast growth factor, and platelet-derived growth factor failed to increase contractile protein synthesis or growth of the heart cells. Insulin and IGF-1 increased growth rates by stimulating anabolic while simultaneously inhibiting catabolic pathways, whereas IGF-2 elevated growth modestly by apparently inhibiting lysosomal proteolysis. Neutralizing antibodies directed against either IGF-1 or IGF-2 or IGF binding protein 3 blocked protein accumulation. A monoclonal antibody directed against the IGF-1 receptor also inhibited changes in protein turnover provoked by recombinant human IGF-1 but not IGF-2. Of the other growth factors tested, only transforming growth factor-beta 1 increased the fractional rate of myosin heavy chain (MHC) synthesis, with beta-MHC synthesis being elevated and alpha-MHC synthesis being suppressed. However, the other growth factors were able to modestly stimulate the rate of DNA synthesis in this preparation. Bromodeoxyuridine labeling revealed that these growth factors increased DNA synthesis in myocytes and nonmyocytes alike, but the heart cells displayed neither karyokinesis or cytokinesis. In contrast, cocultures of cardiac myocytes and nonmyocytes and nonmyocyte-conditioned culture medium failed to enhance the rate of cardiac MHC synthesis or its accumulation, implying that quiescent heart cells do not respond to "conditioning" by cardiac nonmyocytes. These findings demonstrated that insulin and the IGFs promote passively loaded cultured adult rabbit heart cells to hypertrophy but suggest that other growth factors tested may be limited in this regard.

Cellular Strategies for Regulating Functional and Nonfunctional Protein Aggregation

PubMed Central

Gsponer, Jörg; Babu, M. Madan

2012-01-01

Summary Growing evidence suggests that aggregation-prone proteins are both harmful and functional for a cell. How do cellular systems balance the detrimental and beneficial effect of protein aggregation? We reveal that aggregation-prone proteins are subject to differential transcriptional, translational, and degradation control compared to nonaggregation-prone proteins, which leads to their decreased synthesis, low abundance, and high turnover. Genetic modulators that enhance the aggregation phenotype are enriched in genes that influence expression homeostasis. Moreover, genes encoding aggregation-prone proteins are more likely to be harmful when overexpressed. The trends are evolutionarily conserved and suggest a strategy whereby cellular mechanisms specifically modulate the availability of aggregation-prone proteins to (1) keep concentrations below the critical ones required for aggregation and (2) shift the equilibrium between the monomeric and oligomeric/aggregate form, as explained by Le Chatelier’s principle. This strategy may prevent formation of undesirable aggregates and keep functional assemblies/aggregates under control. PMID:23168257

Removal of S6K1 and S6K2 Leads to Divergent Alterations in Learning, Memory, and Synaptic Plasticity

ERIC Educational Resources Information Center

Antion, Marcia D.; Merhav, Maayan; Hoeffer, Charles A.; Reis, Gerald; Kozma, Sara C.; Thomas, George; Schuman Erin M.; Rosenblum, Kobi; Klann, Eric

2008-01-01

Protein synthesis is required for the expression of enduring memories and long-lasting synaptic plasticity. During cellular proliferation and growth, S6 kinases (S6Ks) are activated and coordinate the synthesis of de novo proteins. We hypothesized that protein synthesis mediated by S6Ks is critical for the manifestation of learning, memory, and…

The GARP complex is required for cellular sphingolipid homeostasis.

PubMed

Fröhlich, Florian; Petit, Constance; Kory, Nora; Christiano, Romain; Hannibal-Bach, Hans-Kristian; Graham, Morven; Liu, Xinran; Ejsing, Christer S; Farese, Robert V; Walther, Tobias C

2015-09-10

Sphingolipids are abundant membrane components and important signaling molecules in eukaryotic cells. Their levels and localization are tightly regulated. However, the mechanisms underlying this regulation remain largely unknown. In this study, we identify the Golgi-associated retrograde protein (GARP) complex, which functions in endosome-to-Golgi retrograde vesicular transport, as a critical player in sphingolipid homeostasis. GARP deficiency leads to accumulation of sphingolipid synthesis intermediates, changes in sterol distribution, and lysosomal dysfunction. A GARP complex mutation analogous to a VPS53 allele causing progressive cerebello-cerebral atrophy type 2 (PCCA2) in humans exhibits similar, albeit weaker, phenotypes in yeast, providing mechanistic insights into disease pathogenesis. Inhibition of the first step of de novo sphingolipid synthesis is sufficient to mitigate many of the phenotypes of GARP-deficient yeast or mammalian cells. Together, these data show that GARP is essential for cellular sphingolipid homeostasis and suggest a therapeutic strategy for the treatment of PCCA2.

Influence of Synthesis Temperature on the Growth and Surface Morphology of Co3O4 Nanocubes for Supercapacitor Applications

PubMed Central

Samal, Rashmirekha; Dash, Barsha; Sarangi, Chinmaya Kumar; Subbaiah, Tondepu; Senanayake, Gamini; Minakshi, Manickam

2017-01-01

A facile hydrothermal route to control the crystal growth on the synthesis of Co3O4 nanostructures with cube-like morphologies has been reported and tested its suitability for supercapacitor applications. The chemical composition and morphologies of the as-prepared Co3O4 nanoparticles were extensively characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Varying the temperature caused considerable changes in the morphology, the electrochemical performance increased with rising temperature, and the redox reactions become more reversible. The results showed that the Co3O4 synthesized at a higher temperature (180 °C) demonstrated a high specific capacitance of 833 F/g. This is attributed to the optimal temperature and the controlled growth of nanocubes. PMID:29088061

A dynamic cellular vertex model of growing epithelial tissues

NASA Astrophysics Data System (ADS)

Lin, Shao-Zhen; Li, Bo; Feng, Xi-Qiao

2017-04-01

Intercellular interactions play a significant role in a wide range of biological functions and processes at both the cellular and tissue scales, for example, embryogenesis, organogenesis, and cancer invasion. In this paper, a dynamic cellular vertex model is presented to study the morphomechanics of a growing epithelial monolayer. The regulating role of stresses in soft tissue growth is revealed. It is found that the cells originating from the same parent cell in the monolayer can orchestrate into clustering patterns as the tissue grows. Collective cell migration exhibits a feature of spatial correlation across multiple cells. Dynamic intercellular interactions can engender a variety of distinct tissue behaviors in a social context. Uniform cell proliferation may render high and heterogeneous residual compressive stresses, while stress-regulated proliferation can effectively release the stresses, reducing the stress heterogeneity in the tissue. The results highlight the critical role of mechanical factors in the growth and morphogenesis of epithelial tissues and help understand the development and invasion of epithelial tumors.

HSF1 critically attunes proteotoxic stress sensing by mTORC1 to combat stress and promote growth.

PubMed

Su, Kuo-Hui; Cao, Junyue; Tang, Zijian; Dai, Siyuan; He, Yishu; Sampson, Stephen Byers; Benjamin, Ivor J; Dai, Chengkai

2016-05-01

To cope with proteotoxic stress, cells attenuate protein synthesis. However, the precise mechanisms underlying this fundamental adaptation remain poorly defined. Here we report that mTORC1 acts as an immediate cellular sensor of proteotoxic stress. Surprisingly, the multifaceted stress-responsive kinase JNK constitutively associates with mTORC1 under normal growth conditions. On activation by proteotoxic stress, JNK phosphorylates both RAPTOR at S863 and mTOR at S567, causing partial disintegration of mTORC1 and subsequent translation inhibition. Importantly, HSF1, the central player in the proteotoxic stress response (PSR), preserves mTORC1 integrity and function by inactivating JNK, independently of its canonical transcriptional action. Thereby, HSF1 translationally augments the PSR. Beyond promoting stress resistance, this intricate HSF1-JNK-mTORC1 interplay, strikingly, regulates cell, organ and body sizes. Thus, these results illuminate a unifying mechanism that controls stress adaptation and growth.

Elastic force restricts growth of the murine utricle

PubMed Central

Gnedeva, Ksenia; Jacobo, Adrian; Salvi, Joshua D; Petelski, Aleksandra A; Hudspeth, A J

2017-01-01

Dysfunctions of hearing and balance are often irreversible in mammals owing to the inability of cells in the inner ear to proliferate and replace lost sensory receptors. To determine the molecular basis of this deficiency we have investigated the dynamics of growth and cellular proliferation in a murine vestibular organ, the utricle. Based on this analysis, we have created a theoretical model that captures the key features of the organ’s morphogenesis. Our experimental data and model demonstrate that an elastic force opposes growth of the utricular sensory epithelium during development, confines cellular proliferation to the organ’s periphery, and eventually arrests its growth. We find that an increase in cellular density and the subsequent degradation of the transcriptional cofactor Yap underlie this process. A reduction in mechanical constraints results in accumulation and nuclear translocation of Yap, which triggers proliferation and restores the utricle’s growth; interfering with Yap’s activity reverses this effect. DOI: http://dx.doi.org/10.7554/eLife.25681.001 PMID:28742024

Maturational alterations in gap junction expression and associated collagen synthesis in response to tendon function.

PubMed

Young, N J; Becker, D L; Fleck, R A; Goodship, A E; Patterson-Kane, J C

2009-07-01

tissue and PINP expression per tenocyte also decreased with maturation in the SDFT. In the CDET PINP and PIIINP expression per tenocyte increased in the adult, and exceeded those in the adult SDFT. The level of PINP per mm(2) was greater in the adult CDET than in the SDFT despite the higher cellularity of the latter tendon. In the adult SDFT, levels of PIIINP were greater than those of PINP, suggesting relatively greater synthesis of a weaker form of collagen previously associated with microdamage. Tenocytes in monolayers showed differences in Cx43 and Cx32 expression compared with those in tissue, however there were age- and tendon-specific phenotypic differences, with a longer time for 50% recovery of fluorescence after photobleaching in adult SDFT cells compared with those from the CDET and immature SDFT. As cellularity reduces following growth in the SDFT, a failure of the remaining tenocytes to show a compensatory increase in GJ expression and collagen synthesis may explain why cell populations are not able to respond to exercise and to repair microdamage in some adult athletes. Enhancing GJIC in mature energy-storing tendons could provide a strategy to increase the cellular synthetic and reparative capacity.

Role of Fatty Acid Kinase in Cellular Lipid Homeostasis and SaeRS-Dependent Virulence Factor Expression in Staphylococcus aureus.

PubMed

Ericson, Megan E; Subramanian, Chitra; Frank, Matthew W; Rock, Charles O

2017-08-01

The SaeRS two-component system is a master activator of virulence factor transcription in Staphylococcus aureus , but the cellular factors that control its activity are unknown. Fatty acid (FA) kinase is a two-component enzyme system required for extracellular FA uptake and SaeRS activity. Here, we demonstrate the existence of an intracellular nonesterified FA pool in S. aureus that is elevated in strains lacking FA kinase activity. SaeRS-mediated transcription is restored in FA kinase-negative strains when the intracellular FA pool is reduced either by growth with FA-depleted bovine serum albumin to extract the FA into the medium or by the heterologous expression of Neisseria gonorrhoeae acyl-acyl carrier protein synthetase to activate FA for phospholipid synthesis. These data show that FAs act as negative regulators of SaeRS signaling, and FA kinase activates SaeRS-dependent virulence factor production by lowering inhibitory FA levels. Thus, FA kinase plays a role in cellular lipid homeostasis by activating FA for incorporation into phospholipid, and it indirectly regulates SaeRS signaling by maintaining a low intracellular FA pool. IMPORTANCE The SaeRS two-component system is a master transcriptional activator of virulence factor production in response to the host environment in S. aureus , and strains lacking FA kinase have severely attenuated SaeRS-dependent virulence factor transcription. FA kinase is required for the activation of exogenous FAs, and it plays a role in cellular lipid homeostasis by recycling cellular FAs into the phospholipid biosynthetic pathway. Activation of the sensor kinase, SaeS, is mediated by its membrane anchor domain, and the FAs which accumulate in FA kinase knockout strains are potent inhibitors of SaeS-dependent signaling. This work identifies FAs as physiological effectors for the SaeRS system and reveals a connection between cellular lipid homeostasis and the regulation of virulence factor transcription. FA kinase is widely

Heterologous Synthesis and Recovery of Advanced Biofuels from Bacterial Cell Factories.

PubMed

Malik, Sana; Afzal, Ifrah; Mehmood, Muhammad Aamer; Al Doghaither, Huda; Rahimuddin, Sawsan Abdulaziz; Gull, Munazza; Nahid, Nazia

2018-01-01

Microbial engineering to produce advanced biofuels is currently the most encouraging approach in renewable energy. Heterologous synthesis of biofuels and other useful industrial chemicals using bacterial cell factories has radically diverted the attentions from the native synthesis of these compounds. However, recovery of biofuels from the media and cellular toxicity are the main hindrances to successful commercialization of advanced biofuels. Therefore, membrane transporter engineering is gaining increasing attentions from all over the world. The main objective of this review is to explore the ways to increase the microbial production of biofuels by counteracting the cellular toxicity and facilitating their easier recovery from media. Microbial synthesis of industrially viable compounds such as biofuels has been increased due to genomic revolution. Moreover, advancements in protein engineering, gene regulation, pathway portability, metabolic engineering and synthetic biology led the focus towards the development of robust and cost-effective systems for biofuel production. The most convenient way to combat cellular toxicity and to secrete biofuels is the use of membrane transport system. The use of membrane transporters is currently a serious oversight as do not involve chemical changes and contribute greatly to efflux biofuels in extracellular milieu. However, overexpression of transport systems can also be detrimental to cell, so, in future, structure-based engineering of transporters can be employed to evaluate optimum expression range, to increase biofuel specificity and transport rate through structural studies of biofuel molecules. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Cellular imaging using BODIPY-, pyrene- and phthalocyanine-based conjugates.

PubMed

Bizet, Faustine; Ipuy, Martin; Bernhard, Yann; Lioret, Vivian; Winckler, Pascale; Goze, Christine; Perrier-Cornet, Jean-Marie; Decréau, Richard A

2018-01-15

Fluorescent Probes aimed at absorbing in the blue/green region of the spectrum and emitting in the green/red have been synthesized (as the form of dyads-pentads), studied by spectrofluorimetry, and used for cellular imaging. The synthesis of phthalocyanine-pyrene 1 was achieved by cyclotetramerization of pyrenyldicyanobenzene, whereas phthalocyanine-BODIPY 2c was synthesized by Sonogashira coupling between tetraiodophthalocyanine and meso-alkynylBODIPY. The standard four-steps BODIPY synthesis was applied to the BODIPY-pyrene dyad 3 starting from pyrenecarbaldehyde and dimethylpyrrole. 1 H, 13 C, 19 F, 11 BNMR, ICP, MS, and UV/Vis spectroscopic analyses demonstrated that 2c is a mixture of BODIPY-Pc conjugates corresponding to an average ratio of 2.5 BODIPY per Pc unit, where its bis, tris, tetrakis components could not be separated. Fluorescence emission studies (μM concentration in THF) showed that the design of the probes allowed excitation of their antenna (pyrene, BODIPY) in the blue/green region of the spectrum, and subsequent transfer to the acceptor platform (BODIPY, phthalocyanine) followed by its emission in the green/red (with up to 140-350 nm overall Stokes shifts). The fluorescent probes were used for cellular imaging of B16F10 melanoma cells upon solubilization in 1% DMSO containing RPMI or upon encapsulation in liposomes (injection method). Probes were used at 1-10 μM concentrations, cells were fixed with methanol and imaged by biphoton and/or confocal microscopy, showing that probes could achieve the staining of cells membranes and not the nucleus. Copyright © 2017. Published by Elsevier Ltd.

AMPD2 Regulates GTP Synthesis and is Mutated in a Potentially-Treatable Neurodegenerative Brainstem Disorder

PubMed Central

Akizu, Naiara; Cantagrel, Vincent; Schroth, Jana; Cai, Na; Vaux, Keith; McCloskey, Douglas; Naviaux, Robert K.; Vleet, Jeremy Van; Fenstermaker, Ali G.; Silhavy, Jennifer L.; Scheliga, Judith S.; Toyama, Keiko; Morisaki, Hiroko; Sonmez, Fatma Mujgan; Celep, Figen; Oraby, Azza; Zaki, Maha S.; Al-Baradie, Raidah; Faqeih, Eissa; Saleh, Mohammad; Spencer, Emily; Rosti, Rasim Ozgur; Scott, Eric; Nickerson, Elizabeth; Gabriel, Stacey; Morisaki, Takayuki; Holmes, Edward W.; Gleeson, Joseph G.

2013-01-01

Purine biosynthesis and metabolism, conserved in all living organisms, is essential for cellular energy homeostasis and nucleic acids synthesis. The de novo synthesis of purine precursors is under tight negative feedback regulation mediated by adenosine and guanine nucleotides. We describe a new distinct early-onset neurodegenerative condition resulting from mutations in the adenosine monophosphate deaminase 2 gene (AMPD2). Patients have characteristic brain imaging features of pontocerebellar hypoplasia (PCH), due to loss of brainstem and cerebellar parenchyma. We found that AMPD2 plays an evolutionary conserved role in the maintenance of cellular guanine nucleotide pools by regulating the feedback inhibition of adenosine derivatives on de novo purine synthesis. AMPD2 deficiency results in defective GTP-dependent initiation of protein translation, which can be rescued by administration of purine precursors. These data suggest AMPD2-related PCH as a new, potentially treatable early-onset neurodegenerative disease. PMID:23911318

Synthesis, crystal growth and studies on non-linear optical property of new chalcones

NASA Astrophysics Data System (ADS)

Sarojini, B. K.; Narayana, B.; Ashalatha, B. V.; Indira, J.; Lobo, K. G.

2006-09-01

The synthesis, crystal growth and non-linear optical (NLO) property of new chalcone derivatives are reported. 4-Propyloxy and 4-butoxy benzaldehydes were made to under go Claisen-Schmidt condensation with 4-methoxy, 4-nitro and 4-phenoxy acetophenones to form corresponding chalcones. The newly synthesized compounds were characterized by analytical and spectral data. The Second harmonic generation (SHG) efficiency of these compounds was measured by powder technique using Nd:YAG laser. Among tested compounds three chalcones showed NLO property. The chalcone 1-(4-methoxyphenyl)-3-(4-propyloxy phenyl)-2-propen-1-one exhibited SHG conversion efficiency 2.7 times that of urea. The bulk crystal of 1-(4-methoxyphenyl)-3-(4-butoxyphenyl)-2-propen-1-one (crystal size 65×28×15 mm 3) was grown by slow-evaporation technique from acetone. Microhardness of the crystal was tested by Vicker's microhardness method.

Iron Reverses Impermeable Chelator Inhibition of DNA Synthesis in CCl39 Cells

NASA Astrophysics Data System (ADS)

Alcain, Francisco J.; Low, Hans; Crane, Frederick L.

1994-08-01

Treatment of Chinese hamster lung fibro-blasts (CCl 39 cells) with the impermeable iron(II) chelator bathophenanthroline disulfonate (BPS) inhibits DNA synthesis when cell growth is initiated with growth factors including epidermal growth factor plus insulin, thrombin, or ceruloplasmin, but not with 10% fetal calf serum. The BPS treatment inhibits transplasma membrane electron transport. The treatment leads to release of iron from the cells as determined by BPS iron(II) complex formation over 90 min. Growth factor stimulation of DNA synthesis and electron transport are restored by addition of di- or trivalent iron to the cells in the form of ferric ammonium citrate, ferrous ammonium sulfate, or diferric transferrin. The effect with BPS differs from the inhibition of growth by hydroxyurea, which acts on the ribonucleotide reductase, or diethylenetriaminepentaacetic acid, which is another impermeable chelating agent, in that these agents inhibit growth in 10% fetal calf serum. The BPS effect is consistent with removal of iron from a site on the cell surface that controls DNA synthesis.

Controlling cytoplasmic c-Fos controls tumor growth in the peripheral and central nervous system.

PubMed

Gil, Germán A; Silvestre, David C; Tomasini, Nicolás; Bussolino, Daniela F; Caputto, Beatriz L

2012-06-01

Some 20 years ago c-Fos was identified as a member of the AP-1 family of inducible transcription factors (Angel and Karin in Biochim Biophys Acta 1072:129-157, 1991). More recently, an additional activity was described for this protein: it associates to the endoplasmic reticulum and activates the biosynthesis of phospholipids (Bussolino et al. in FASEB J 15:556-558, 2001), (Gil et al. in Mol Biol Cell 15:1881-1894, 2004), the quantitatively most important components of cellular membranes. This latter activity of c-Fos determines the rate of membrane genesis and consequently of growth in differentiating PC12 cells (Gil et al. in Mol Biol Cell 15:1881-1894, 2004). In addition, it has been shown that c-Fos is over-expressed both in PNS and CNS tumors (Silvestre et al. in PLoS One 5(3):e9544, 2010). Herein, it is shown that c-Fos-activated phospholipid synthesis is required to support membrane genesis during the exacerbated growth characteristic of brain tumor cells. Specifically blocking c-Fos-activated phospholipid synthesis significantly reduces proliferation of tumor cells in culture. Blocking c-Fos expression also prevents tumor progression in mice intra-cranially xeno-grafted human brain tumor cells. In NPcis mice, an animal model of the human disease Neurofibromatosis Type I (Cichowski and Jacks in Cell 104:593-604, 2001), animals spontaneously develop tumors of the PNS and the CNS, provided they express c-Fos (Silvestre et al. in PLoS One 5(3):e9544, 2010). Treatment of PNS tumors with an antisense oligonucleotide that specifically blocks c-Fos expression also blocks tumor growth in vivo. These results disclose cytoplasmic c-Fos as a new target for effectively controlling brain tumor growth.

Synthesis of Graphite Encapsulated Metal Nanoparticles and Metal Catalyzed Nanotubes

NASA Technical Reports Server (NTRS)

vanderWal, R. L.; Dravid, V. P.

1999-01-01

This work focuses on the growth and inception of graphite encapsulated metal nanoparticles and metal catalyzed nanotubes using combustion chemistry. Deciphering the inception and growth mechanism(s) for these unique nanostructures is essential for purposeful synthesis. Detailed knowledge of these mechanism(s) may yield insights into alternative synthesis pathways or provide data on unfavorable conditions. Production of these materials is highly desirable given many promising technological applications.

[Enhanced ε-poly-L-lysine production by improving cellular activity during fermentation].

PubMed

Liu, Shengrong; Wu, Qingping; Zhang, Jumei; Yang, Xiaojuan; Cai, Shuzhen

2015-06-04

To assess the effect of cellular activity on ε-poly-1-lysine (ε-PL) biosynthesis and thereby to rationally improve the production, we studied the cellular activity, ε-PL formation and other parameters cross flask fermentation by Streptomyces ahygroscopicus. Laser scanning confocal microscopy and a colorimetric method were used to determine cellular activity using BacLight Live/Dead and 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) as viable stains. To enhance the activity of the cells in the ε-PL production period, yeast extract was added. During ε-PL submerged fermentation in flasks, most cells were active in the growth period (0 - 16 h); cells had metabolic activity in the growth and earlier ε-PL production periods between 0 and 30 h fermentation. Almost no activity was detected after 48 h fermentation when no ε-PL was produced. The improved fermentation achieved 2. 24 g/L ε-PL from 1.04 g/L. Biosynthesis of ε-PL can be boosted by up-regulating cell activity in its production phase.

The effect of epidermal growth factor on neonatal incisor differentiation in the mouse.

PubMed

Topham, R T; Chiego, D J; Gattone, V H; Hinton, D A; Klein, R M

1987-12-01

The effect of epidermal growth factor (EGF) on cellular differentiation of the neonatal mouse mandibular incisor was examined autoradiographically using tritiated thymidine ([3H]TDR) and tritiated proline ([3H]PRO). On days 0 (day of birth), 1, and 2, EGF was administered (3 micrograms/g body wt) sc to neonates. Mice were killed on Days 1, 4, 7, 10, and 13 after birth and were injected with either [3H]TDR or [3H]PRO 1 hr before death. [3H]TDR was used to analyze cell proliferation in eight cell types in the developing mouse incisor including upper (lingual) and lower (buccal) pulpal fibroblasts, preodontoblasts, inner and outer enamel epithelial cells (IEE and OEE), stratum intermedium (SI), stellate reticulum (SR), and periodontal ligament (PDL) fibroblasts. [3H]PRO was used to analyze protein synthesis in ameloblasts, and their secretion products (enamel and dentin), as well as PDL fibroblasts. The selected EGF injection scheme elicited acceleration of incisor eruption with minimal growth retardation. At Day 1, the upper and lower pulp, preodontoblasts, SI, and SR showed a significant decrease in labeling index (LI) 24 hr after a single EGF injection. After multiple injections (Days 0, 1, 2), two LI patterns were observed. In lower pulp, preodontoblasts, IEE, SI, SR, and OEE, a posteruptive change in LI was observed. In contrast, the upper pulp and PDL regions demonstrated a direct temporal relationship with eruption. Autoradiographic analysis with [3H]PRO indicated that EGF treatment caused significant increases in grain counts per unit area in ameloblast, odontoblast, and PDL regions studied. Significant differences were found in all four regions studied (ameloblasts, enamel, odontoblasts, dentin) at the 45-microns-tall ameloblast level as well as ameloblasts and odontoblasts at the 30-microns level at 13 days of age. The PDL demonstrated significant differences at all locations studied (base, 30 microns, 45 microns,) in 4-, 7-, and 13-day-old mice

Phosphatidylcholine synthesis is required for optimal function of Legionella pneumophila virulence determinants.

PubMed

Conover, Gloria M; Martinez-Morales, Fernando; Heidtman, Matthew I; Luo, Zhao-Qing; Tang, May; Chen, Cui; Geiger, Otto; Isberg, Ralph R

2008-02-01

The function of phosphatidylcholine (PC) in the bacterial cell envelope remains cryptic. We show here that productive interaction of the respiratory pathogen Legionella pneumophila with host cells requires bacterial PC. Synthesis of the lipid in L. pneumophila was shown to occur via either phospholipid N-methyltransferase (PmtA) or phosphatidylcholine synthase (PcsA), but the latter pathway was demonstrated to be of predominant importance. Loss of PC from the cell envelope caused lowered yields of L. pneumophila within macrophages as well as loss of high multiplicity cytotoxicity, while mutants defective in PC synthesis could be complemented either by reintroduction of PcsA or by overproduction of PmtA. The lowered yields and reduced cytotoxicity in mutants with defective PC biosynthesis were due to three related defects. First, there was a poorly functioning Dot/Icm apparatus, which delivers substrates required for intracellular growth into the cytosol of infected cells. Second, there was reduced bacterial binding to macrophages, possibly due to loss of PC or a PC derivative on the bacterium that is recognized by the host cell. Finally, strains lacking PC had low steady-state levels of flagellin protein, a deficit that had been previously associated with the phenotypes of lowered cytotoxicity and poor cellular adhesion.

Cellular signaling by fibroblast growth factors (FGFs) and their receptors (FGFRs) in male reproduction.

PubMed

Cotton, Leanne M; O'Bryan, Moira K; Hinton, Barry T

2008-04-01

The major function of the reproductive system is to ensure the survival of the species by passing on hereditary traits from one generation to the next. This is accomplished through the production of gametes and the generation of hormones that function in the maturation and regulation of the reproductive system. It is well established that normal development and function of the male reproductive system is mediated by endocrine and paracrine signaling pathways. Fibroblast growth factors (FGFs), their receptors (FGFRs), and signaling cascades have been implicated in a diverse range of cellular processes including: proliferation, apoptosis, cell survival, chemotaxis, cell adhesion, motility, and differentiation. The maintenance and regulation of correct FGF signaling is evident from human and mouse genetic studies which demonstrate that mutations leading to disruption of FGF signaling cause a variety of developmental disorders including dominant skeletal diseases, infertility, and cancer. Over the course of this review, we will provide evidence for differential expression of FGFs/FGFRs in the testis, male germ cells, the epididymis, the seminal vesicle, and the prostate. We will show that this signaling cascade has an important role in sperm development and maturation. Furthermore, we will demonstrate that FGF/FGFR signaling is essential for normal epididymal function and prostate development. To this end, we will provide evidence for the involvement of the FGF signaling system in the regulation and maintenance of the male reproductive system.

Complex, multi-scale small intestinal topography replicated in cellular growth substrates fabricated via chemical vapor deposition of Parylene C.

PubMed

Koppes, Abigail N; Kamath, Megha; Pfluger, Courtney A; Burkey, Daniel D; Dokmeci, Mehmet; Wang, Lin; Carrier, Rebecca L

2016-08-22

Native small intestine possesses distinct multi-scale structures (e.g., crypts, villi) not included in traditional 2D intestinal culture models for drug delivery and regenerative medicine. The known impact of structure on cell function motivates exploration of the influence of intestinal topography on the phenotype of cultured epithelial cells, but the irregular, macro- to submicron-scale features of native intestine are challenging to precisely replicate in cellular growth substrates. Herein, we utilized chemical vapor deposition of Parylene C on decellularized porcine small intestine to create polymeric intestinal replicas containing biomimetic irregular, multi-scale structures. These replicas were used as molds for polydimethylsiloxane (PDMS) growth substrates with macro to submicron intestinal topographical features. Resultant PDMS replicas exhibit multiscale resolution including macro- to micro-scale folds, crypt and villus structures, and submicron-scale features of the underlying basement membrane. After 10 d of human epithelial colorectal cell culture on PDMS substrates, the inclusion of biomimetic topographical features enhanced alkaline phosphatase expression 2.3-fold compared to flat controls, suggesting biomimetic topography is important in induced epithelial differentiation. This work presents a facile, inexpensive method for precisely replicating complex hierarchal features of native tissue, towards a new model for regenerative medicine and drug delivery for intestinal disorders and diseases.

Cellular metabolic rates from primary dermal fibroblast cells isolated from birds of different body masses.

PubMed

Jimenez, Ana Gabriela; Williams, Joseph B

2014-10-01

The rate of metabolism is the speed at which organisms use energy, an integration of energy transformations within the body; it governs biological processes that influence rates of growth and reproduction. Progress at understanding functional linkages between whole organism metabolic rate and underlying mechanisms that influence its magnitude has been slow despite the central role this issue plays in evolutionary and physiological ecology. Previous studies that have attempted to relate how cellular processes translate into whole-organism physiology have done so over a range of body masses of subjects. However, the data still remains controversial when observing metabolic rates at the cellular level. To bridge the gap between these ideas, we examined cellular metabolic rate of primary dermal fibroblasts isolated from 49 species of birds representing a 32,000-fold range in body masses to test the hypothesis that metabolic rate of cultured cells scales with body size. We used a Seahorse XF-96 Extracellular flux analyzer to measure cellular respiration in fibroblasts. Additionally, we measured fibroblast size and mitochondrial content. We found no significant correlation between cellular metabolic rate, cell size, or mitochondrial content and body mass. Additionally, there was a significant relationship between cellular basal metabolic rate and proton leak in these cells. We conclude that metabolic rate of cells isolated in culture does not scale with body mass, but cellular metabolic rate is correlated to growth rate in birds. Copyright © 2014 Elsevier Inc. All rights reserved.

Mechanical tension as a driver of connective tissue growth in vitro.

PubMed

Wilson, Cameron J; Pearcy, Mark J; Epari, Devakara R

2014-07-01

We propose the progressive mechanical expansion of cell-derived tissue analogues as a novel, growth-based approach to in vitro tissue engineering. The prevailing approach to producing tissue in vitro is to culture cells in an exogenous "scaffold" that provides a basic structure and mechanical support. This necessarily pre-defines the final size of the implantable material, and specific signals must be provided to stimulate appropriate cell growth, differentiation and matrix formation. In contrast, surgical skin expansion, driven by increments of stretch, produces increasing quantities of tissue without trauma or inflammation. This suggests that connective tissue cells have the innate ability to produce growth in response to elevated tension. We posit that this capacity is maintained in vitro, and that order-of-magnitude growth may be similarly attained in self-assembling cultures of cells and their own extracellular matrix. The hypothesis that growth of connective tissue analogues can be induced by mechanical expansion in vitro may be divided into three components: (1) tension stimulates cell proliferation and extracellular matrix synthesis; (2) the corresponding volume increase will relax the tension imparted by a fixed displacement; (3) the repeated application of static stretch will produce sustained growth and a tissue structure adapted to the tensile loading. Connective tissues exist in a state of residual tension, which is actively maintained by resident cells such as fibroblasts. Studies in vitro and in vivo have demonstrated that cellular survival, reproduction, and matrix synthesis and degradation are regulated by the mechanical environment. Order-of-magnitude increases in both bone and skin volume have been achieved clinically through staged expansion protocols, demonstrating that tension-driven growth can be sustained over prolonged periods. Furthermore, cell-derived tissue analogues have demonstrated mechanically advantageous structural adaptation in

Transition from a planar interface to cellular and dendritic structures during rapid solidification processing

NASA Technical Reports Server (NTRS)

Laxmanan, V.

1986-01-01

The development of theoretical models which characterize the planar-cellular and cell-dendrite transitions is described. The transitions are analyzed in terms of the Chalmers number, the solute Peclet number, and the tip stability parameter, which correlate microstructural features and processing conditions. The planar-cellular transition is examined using the constitutional supercooling theory of Chalmers et al., (1953) and it is observed that the Chalmers number is between 0 and 1 during dendritic and cellular growth. Analysis of cell-dendrite transition data reveal that the transition occurs when the solute Peclet number goes through a minimum, the primary arm spacings go through a maximum, and the Chalmers number is equal to 1/2. The relation between the tip stability parameter and the solute Peclet number is investigated and it is noted that the tip stability parameter is useful for studying dendritic growth in alloys.

Synthesis of heterocycles: Indolo (2,1-a) isoquinolines, renewables, and aptamer ligands for cellular imaging

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

Beasley, Jonathan

2013-01-01

In this thesis, we explore both total syntheses and methodologies of several aromatic heterocyclic molecules. Extensions of the Kraus indole synthesis toward 2-substituted and 2,3-disubstituted indoles, as well as biologically attractive indolo[2,1-a]isoquinolines are described. Recent renewable efforts directed to commodity maleic acid and the first reported furan-based ionic liquids are described. Our total synthesis of mRNA aptamer ligand PDC-Gly, and its dye coupled forms, plus aminoglycoside dye coupled ligands used in molecular imaging, are described.

Mitochondrial protein acetylation mediates nutrient sensing of mitochondrial protein synthesis and mitonuclear protein balance.

PubMed

Di Domenico, Antonella; Hofer, Annette; Tundo, Federica; Wenz, Tina

2014-11-01

Changes in nutrient supply require global metabolic reprogramming to optimize the utilization of the nutrients. Mitochondria as a central component of the cellular metabolism play a key role in this adaptive process. Since mitochondria harbor their own genome, which encodes essential enzymes, mitochondrial protein synthesis is a determinant of metabolic adaptation. While regulation of cytoplasmic protein synthesis in response to metabolic challenges has been studied in great detail, mechanisms which adapt mitochondrial translation in response to metabolic challenges remain elusive. Our results suggest that the mitochondrial acetylation status controlled by Sirt3 and its proposed opponent GCN5L1 is an important regulator of the metabolic adaptation of mitochondrial translation. Moreover, both proteins modulate regulators of cytoplasmic protein synthesis as well as the mitonuclear protein balance making Sirt3 and GCN5L1 key players in synchronizing mitochondrial and cytoplasmic translation. Our results thereby highlight regulation of mitochondrial translation as a novel component in the cellular nutrient sensing scheme and identify mitochondrial acetylation as a new regulatory principle for the metabolic competence of mitochondrial protein synthesis. © 2014 International Union of Biochemistry and Molecular Biology.

Studies on the Role of RNA Synthesis in Auxin Induction of Cell Enlargement 1

PubMed Central

Nooden, Larry D.

1968-01-01

Selective inhibitors were used to study the connection between nucleic acid synthesis and indoleacetic acid (IAA) induction of cell enlargement. Actinomycin D (act D) and azaguanine (azaG) almost completely inhibit IAA-induced growth in aged artichoke tuber disks when they are added simultaneously with IAA. In contrast, when they are added 24 hours after the hormone, these inhibitors have little or no effect on the induced growth which continues for 48 hours or more with little or no inhibition. Inhibitors of protein synthesis still stop growth when applied 24 hours after the IAA, thus protein synthesis and presumably supporting metabolism are still essential. In corn coleoptile sections auxin-induced growth did not show any pronounced tendency to become less sensitive to act D as the IAA treatment progressed. Act D did not completely inhibit the response to IAA unless the sections were pretreated with act D for 6 hours. In contrast to act D, cordycepin produced almost complete inhibition of IAA-induced growth when added with the IAA. Although IAA has a very large and very rapid stimulatory effect (within 10 min) on incorporation of 32P-orthophosphate into RNA in disks, it did not cause a detectable change in the base composition of the RNA synthesized. Furthermore, the promotive effect could be accounted for through increased uptake of the 32P. That much of the RNA synthesis in these tissues is not necessary for auxin action is indicated by the results with fluorouracil (FU). FU strongly inhibits RNA synthesis, probably acting preferentially on ribosomal RNA synthesis, without inhibiting auxin-induced growth in the disks or coleoptile sections. FU also strongly inhibited respiration in auxin-treated disks indicating that the large promotion of respiration by auxin likewise may not be entirely necessary for growth. At least in the artichoke disks, RNA synthesis is required for auxin induction of cell enlargement and not for cell enlargement itself. The possible

Drosophila larvae synthesize the putative oncometabolite L-2-hydroxyglutarate during normal developmental growth

PubMed Central

Li, Hongde; Chawla, Geetanjali; Hurlburt, Alexander J.; Sterrett, Maria C.; Zaslaver, Olga; Cox, James; Karty, Jonathan A.; Rosebrock, Adam P.; Caudy, Amy A.

2017-01-01

L-2-hydroxyglutarate (L-2HG) has emerged as a putative oncometabolite that is capable of inhibiting enzymes involved in metabolism, chromatin modification, and cell differentiation. However, despite the ability of L-2HG to interfere with a broad range of cellular processes, this molecule is often characterized as a metabolic waste product. Here, we demonstrate that Drosophila larvae use the metabolic conditions established by aerobic glycolysis to both synthesize and accumulate high concentrations of L-2HG during normal developmental growth. A majority of the larval L-2HG pool is derived from glucose and dependent on the Drosophila estrogen-related receptor (dERR), which promotes L-2HG synthesis by up-regulating expression of the Drosophila homolog of lactate dehydrogenase (dLdh). We also show that dLDH is both necessary and sufficient for directly synthesizing L-2HG and the Drosophila homolog of L-2-hydroxyglutarate dehydrogenase (dL2HGDH), which encodes the enzyme that breaks down L-2HG, is required for stage-specific degradation of the L-2HG pool. In addition, dLDH also indirectly promotes L-2HG accumulation via synthesis of lactate, which activates a metabolic feed-forward mechanism that inhibits dL2HGDH activity and stabilizes L-2HG levels. Finally, we use a genetic approach to demonstrate that dLDH and L-2HG influence position effect variegation and DNA methylation, suggesting that this compound serves to coordinate glycolytic flux with epigenetic modifications. Overall, our studies demonstrate that growing animal tissues synthesize L-2HG in a controlled manner, reveal a mechanism that coordinates glucose catabolism with L-2HG synthesis, and establish the fly as a unique model system for studying the endogenous functions of L-2HG during cell growth and proliferation. PMID:28115720

Drosophila larvae synthesize the putative oncometabolite L-2-hydroxyglutarate during normal developmental growth.

PubMed

Li, Hongde; Chawla, Geetanjali; Hurlburt, Alexander J; Sterrett, Maria C; Zaslaver, Olga; Cox, James; Karty, Jonathan A; Rosebrock, Adam P; Caudy, Amy A; Tennessen, Jason M

2017-02-07

L-2-hydroxyglutarate (L-2HG) has emerged as a putative oncometabolite that is capable of inhibiting enzymes involved in metabolism, chromatin modification, and cell differentiation. However, despite the ability of L-2HG to interfere with a broad range of cellular processes, this molecule is often characterized as a metabolic waste product. Here, we demonstrate that Drosophila larvae use the metabolic conditions established by aerobic glycolysis to both synthesize and accumulate high concentrations of L-2HG during normal developmental growth. A majority of the larval L-2HG pool is derived from glucose and dependent on the Drosophila estrogen-related receptor (dERR), which promotes L-2HG synthesis by up-regulating expression of the Drosophila homolog of lactate dehydrogenase (dLdh). We also show that dLDH is both necessary and sufficient for directly synthesizing L-2HG and the Drosophila homolog of L-2-hydroxyglutarate dehydrogenase (dL2HGDH), which encodes the enzyme that breaks down L-2HG, is required for stage-specific degradation of the L-2HG pool. In addition, dLDH also indirectly promotes L-2HG accumulation via synthesis of lactate, which activates a metabolic feed-forward mechanism that inhibits dL2HGDH activity and stabilizes L-2HG levels. Finally, we use a genetic approach to demonstrate that dLDH and L-2HG influence position effect variegation and DNA methylation, suggesting that this compound serves to coordinate glycolytic flux with epigenetic modifications. Overall, our studies demonstrate that growing animal tissues synthesize L-2HG in a controlled manner, reveal a mechanism that coordinates glucose catabolism with L-2HG synthesis, and establish the fly as a unique model system for studying the endogenous functions of L-2HG during cell growth and proliferation.

Unique Cellular Organization in the Oldest Root Meristem.

PubMed

Hetherington, Alexander J; Dubrovsky, Joseph G; Dolan, Liam

2016-06-20

Roots and shoots of plant bodies develop from meristems-cell populations that self-renew and produce cells that undergo differentiation-located at the apices of axes [1].The oldest preserved root apices in which cellular anatomy can be imaged are found in nodules of permineralized fossil soils called coal balls [2], which formed in the Carboniferous coal swamp forests over 300 million years ago [3-9]. However, no fossil root apices described to date were actively growing at the time of preservation [3-10]. Because the cellular organization of meristems changes when root growth stops, it has been impossible to compare cellular dynamics as stem cells transition to differentiated cells in extinct and extant taxa [11]. We predicted that meristems of actively growing roots would be preserved in coal balls. Here we report the discovery of the first fossilized remains of an actively growing root meristem from permineralized Carboniferous soil with detail of the stem cells and differentiating cells preserved. The cellular organization of the meristem is unique. The position of the Körper-Kappe boundary, discrete root cap, and presence of many anticlinal cell divisions within a broad promeristem distinguish it from all other known root meristems. This discovery is important because it demonstrates that the same general cellular dynamics are conserved between the oldest extinct and extant root meristems. However, its unique cellular organization demonstrates that extant root meristem organization and development represents only a subset of the diversity that has existed since roots first evolved. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Arabidopsis Small Rubber Particle Protein Homolog SRPs Play Dual Roles as Positive Factors for Tissue Growth and Development and in Drought Stress Responses.

PubMed

Kim, Eun Yu; Park, Ki Youl; Seo, Young Sam; Kim, Woo Taek

2016-04-01

Lipid droplets (LDs) act as repositories for fatty acids and sterols, which are used for various cellular processes such as energy production and membrane and hormone synthesis. LD-associated proteins play important roles in seed development and germination, but their functions in postgermination growth are not well understood. Arabidopsis (Arabidopsis thaliana) contains three SRP homologs (SRP1, SRP2, and SRP3) that share sequence identities with small rubber particle proteins of the rubber tree (Hevea brasiliensis). In this report, the possible cellular roles of SRPs in postgermination growth and the drought tolerance response were investigated. Arabidopsis SRPs appeared to be LD-associated proteins and displayed polymerization properties in vivo and in vitro. SRP-overexpressing transgenic Arabidopsis plants (35S:SRP1, 35S:SRP2, and 35S:SRP3) exhibited higher vegetative and reproductive growth and markedly better tolerance to drought stress than wild-type Arabidopsis. In addition, constitutive over-expression of SRPs resulted in increased numbers of large LDs in postgermination seedlings. In contrast, single (srp1, 35S:SRP2-RNAi, and srp3) and triple (35S:SRP2-RNAi/srp1srp3) loss-of-function mutant lines exhibited the opposite phenotypes. Our results suggest that Arabidopsis SRPs play dual roles as positive factors in postgermination growth and the drought stress tolerance response. The possible relationships between LD-associated proteins and the drought stress response are discussed. © 2016 American Society of Plant Biologists. All Rights Reserved.

Mechanism of growth delay induced in Escherichia coli by near ultraviolet radiation.

PubMed Central

Ramabhadran, T V; Jagger, J

1976-01-01

Continuously growing cultures of E. coli B/r were irradiated with a fluence of broad-band near-ultraviolet radiation (315-405 nm) sufficient to cause extensive growth delay and complete cessation of net RNA synthesis. Chloramphenicol treatment was found to stimulate resumption of RNA synthesis, similar to that observed with chloramphenicol treatment after amino-acid starvation. E. coli strains in which amino-acid starvation does not result in cessation of RNA synthesis ("relaxed" or rel- strains) show no cessation of growth and only a slight effect on the rate of growth or of RNA synthesis. These findings show that such near-UV fluences do not inactivate the RNA synthetic machinery but affect the regulation of RNA synthesis, in a manner similat to that produced by amino-acid starvation. Such regulation is believed to be mediated through alterations in concentration of guanosine tetraphosphate (ppGpp), and our estimations of ppGpp after near-UV irradiation are consistent with such an interpretation. These data, combined with earlier published data, strongly suggest that the mechanism of near-UV-induced growth delay in E. coli involves partial inactivation of certain tRNA species, which is interpreted by the cell in a manner similar to that of amino-acid starvation, causing a rise in ppGpp levels, a shut-off of net RNA synthesis, and the induction of a growth delay. Images PMID:1108019

Extracellular cystatin SN and cathepsin B prevent cellular senescence by inhibiting abnormal glycogen accumulation.

PubMed

Oh, Sang-Seok; Park, Soojong; Lee, Ki-Won; Madhi, Hamadi; Park, Sae Gwang; Lee, Hee Gu; Cho, Yong-Yeon; Yoo, Jiyun; Dong Kim, Kwang

2017-04-06

Cystatin SN (CST1), a known inhibitor of cathepsin B (CatB), has important roles in tumor development. Paradoxically, CatB is a member of the cysteine cathepsin family that acts in cellular processes, such as tumor development and invasion. However, the relationship between CST1 and CatB, and their roles in tumor development are poorly understood. In this study, we observed that the knockdown of CST1 induced the activity of senescence-associated β-galactosidase, a marker of cellular senescence, and expression of senescence-associated secretory phenotype genes, including interleukin-6 and chemokine (C-C motif) ligand 20, in MDA-MB-231 and SW480 cancer cells. Furthermore, CST1 knockdown decreased extracellular CatB activity, and direct CatB inhibition, using specific inhibitors or shCatB, induced cellular senescence. Reconstitution of CST1 restored CatB activity and inhibited cellular senescence in CST1 knockdown cells. CST1 knockdown or CatB inhibition increased glycogen synthase (GS) kinase 3β phosphorylation at serine 9, resulting in the activation of GS and the induction of glycogen accumulation associated with cellular senescence. Importantly, CST1 knockdown suppressed cancer cell proliferation, soft agar colony growth and tumor growth in a xenograft model. These results indicate that CST1-mediated extracellular CatB activity enhances tumor development by preventing cellular senescence. Our findings suggest that antagonists of CST1 or inhibitors of CatB are potential anticancer agents.

The penny pusher: a cellular model of lens growth.

PubMed

Shi, Yanrong; De Maria, Alicia; Lubura, Snježana; Šikić, Hrvoje; Bassnett, Steven

2014-12-16

The mechanisms that regulate the number of cells in the lens and, therefore, its size and shape are unknown. We examined the dynamic relationship between proliferative behavior in the epithelial layer and macroscopic lens growth. The distribution of S-phase cells across the epithelium was visualized by confocal microscopy and cell populations were determined from orthographic projections of the lens surface. The number of S-phase cells in the mouse lens epithelium fell exponentially, to an asymptotic value of approximately 200 cells by 6 months. Mitosis became increasingly restricted to a 300-μm-wide swath of equatorial epithelium, the germinative zone (GZ), within which two peaks in labeling index were detected. Postnatally, the cell population increased to approximately 50,000 cells at 4 weeks of age. Thereafter, the number of cells declined, despite continued growth in lens dimensions. This apparently paradoxical observation was explained by a time-dependent increase in the surface area of cells at all locations. The cell biological measurements were incorporated into a physical model, the Penny Pusher. In this simple model, cells were considered to be of a single type, the proliferative behavior of which depended solely on latitude. Simulations using the Penny Pusher predicted the emergence of cell clones and were in good agreement with data obtained from earlier lineage-tracing studies. The Penny Pusher, a simple stochastic model, offers a useful conceptual framework for the investigation of lens growth mechanisms and provides a plausible alternative to growth models that postulate the existence of lens stem cells. Copyright 2015 The Association for Research in Vision and Ophthalmology, Inc.

The Association of Birth Weight and Infant Growth with Energy Balance-Related Behavior – A Systematic Review and Best-Evidence Synthesis of Human Studies

PubMed Central

Chinapaw, Mai J. M.; Jansma, Elise P.; Vrijkotte, Tanja G. M.; Gemke, Reinoud J. B. J.

2017-01-01

Background Suboptimal prenatal and early postnatal growths are associated with obesity in later life, but the underlying mechanisms are unknown. The aim of this study was to systematically review the literature that reports on the longitudinal association of (i) birth size or (ii) infant growth with later (i) energy intake, (ii) eating behaviors, (iii) physical activity or (iv) sedentary behavior in humans. Methods A comprehensive search of MEDLINE, EMBASE, PsycINFO and The Cochrane Library was conducted to identify relevant publications. We appraised the methodological quality of the studies and synthesized the extracted data through a best-evidence synthesis. Results Data from 41 publications were included. The quality of the studies was high in three papers, moderate in 11 and low in the large majority (n = 27) of papers appraised. Our best-evidence synthesis indicates that there is no evidence for an association of birth weight with later energy intake, eating behavior, physical activity or sedentary behavior. We found moderate evidence for an association of extreme birth weights (at both ends of the spectrum) with lower physical activity levels at a later age. Evidence for the association of infant growth with energy balance-related behavior was generally insufficient. Conclusions We conclude that current evidence does not support an association of early-life growth with energy balance-related behaviors in later life, except for an association of extreme birth weights with later physical activity. PMID:28081150

Effect of TPA on ion fluxes and DNA synthesis in vascular smooth muscle cells

PubMed Central

1985-01-01

Previous reports have suggested that phorbol esters can decrease the affinity of epidermal growth factor (EGF) for its cellular receptors. Investigations of the consequences of the interaction between phorbol esters and EGF, however, have been limited to EGF-stimulated Na/H exchange in A431 cells (Whitely, B., D. Cassel, Y.-X. Zuang, and L. Glaser, 1984, J. Cell Biol., 99:1162-1166). In the present study, the effect of the phorbol ester 12-O-tetradecanoyl phorbol-13-acetate (TPA) on EGF-stimulated ion transport and DNA synthesis was determined in cultured vascular smooth muscle cells (A7r5). It was found that TPA stimulated Na/H exchange when added alone (half-maximal stimulatory concentration, 25 nM). However, when cells were pretreated with TPA and then challenged with EGF, TPA significantly inhibited EGF-stimulated Na/H exchange (78%; half-maximal inhibition [Ki] at 2.5 nM). Subsequently the effects of TPA on Na/K/Cl co-transport were measured. TPA was observed to inhibit Na/K/Cl co-transport (half-maximal inhibitory concentration, 50 nM) and also to inhibit EGF-stimulated Na/K/Cl co-transport (100%; Ki at 5 nM). Finally, the effects of TPA on DNA synthesis were assessed. TPA had a modest stimulatory effect on DNA synthesis (half-maximal stimulatory concentration, 6 nM), but had a significant inhibitory effect on EGF-stimulated DNA synthesis (56%; Ki at 5 nM). These findings suggest that the inhibitory effect of TPA on EGF-receptor functions goes beyond previously reported effects on Na/H exchange in A431 cells and extends to EGF-stimulation of Na/K/Cl co- transport and DNA synthesis in vascular smooth muscle cells. PMID:2410432

High-Concentrate Diet-Induced Change of Cellular Metabolism Leads to Decreases of Immunity and Imbalance of Cellular Activities in Rumen Epithelium.

PubMed

Lu, Zhongyan; Shen, Hong; Shen, Zanming

2018-01-01

In animals, the immune and cellular processes of tissue largely depend on the status of local metabolism. However, in the rumen epithelium, how the cellular metabolism affects epithelial immunity, and cellular processes, when the diet is switched from energy-rich to energy-excess status, with regard to animal production and health, have not as yet been reported. RNA-seq was applied to compare the biological processes altered by an increase of dietary concentration from 10% to 35% with those altered by an increase of dietary concentration from 35% to 65% (dietary concentrate: the non-grass component in diet, including corn, soya bean meal and additive. High concentrate diet composed of 35% grass, 55% corn, 8% soya bean meal and 2% additive). In addition to the functional analysis of enriched genes in terms of metabolism, the immune system, and cellular process, the highly correlated genes to the enriched metabolism genes were identified, and the function and signaling pathways related to the differentially expressed neighbors were compared among the groups. The variation trends of molar proportions of ruminal SCFAs and those of enriched pathways belonging to metabolism, immune system, and cellular process were altered with the change of diets. With regard to metabolism, lipid metabolism and amino acid metabolism were most affected. According to the correlation analysis, both innate and adaptive immune responses were promoted by the metabolism genes enriched under the 65% concentrate diet. However, the majority of immune responses were suppressed under the 35% concentrate diet. Moreover, the exclusive upregulation of cell growth and dysfunction of cellular transport and catabolism were induced by the metabolism genes enriched under the 65% concentrate diet. On the contrary, a balanced regulation of cellular processes was detected under the 35% concentrate diet. These results indicated that the alterations of cellular metabolism promote the alterations in cellular

Graphene Synthesis by Plasma-Enhanced CVD Growth with Ethanol

DOE PAGES

Campo, Teresa; Cotto, María; Márquez, Francisco; ...

2016-03-01

A modified route to synthesize graphene flakes is proposed using the Chemical Vapor Deposition (CVD) technique, by using copper substrates as supports. The carbon source used was ethanol, the synthesis temperature was 950°C and the pressure was controlled along the whole process. In this CVD synthesis process the incorporation of the carbon source was produced at low pressure and 950°C inducing the appearance of a plasma blue flash inside the quartz tube. Apparently, the presence of this plasma blue flash is required for obtaining graphene flakes. The synthesized graphene was characterized by different techniques, showing the presence of non-oxidized graphenemore » with high purity.« less

Growth control of the eukaryote cell: a systems biology study in yeast.

PubMed

Castrillo, Juan I; Zeef, Leo A; Hoyle, David C; Zhang, Nianshu; Hayes, Andrew; Gardner, David Cj; Cornell, Michael J; Petty, June; Hakes, Luke; Wardleworth, Leanne; Rash, Bharat; Brown, Marie; Dunn, Warwick B; Broadhurst, David; O'Donoghue, Kerry; Hester, Svenja S; Dunkley, Tom Pj; Hart, Sarah R; Swainston, Neil; Li, Peter; Gaskell, Simon J; Paton, Norman W; Lilley, Kathryn S; Kell, Douglas B; Oliver, Stephen G

2007-01-01

Cell growth underlies many key cellular and developmental processes, yet a limited number of studies have been carried out on cell-growth regulation. Comprehensive studies at the transcriptional, proteomic and metabolic levels under defined controlled conditions are currently lacking. Metabolic control analysis is being exploited in a systems biology study of the eukaryotic cell. Using chemostat culture, we have measured the impact of changes in flux (growth rate) on the transcriptome, proteome, endometabolome and exometabolome of the yeast Saccharomyces cerevisiae. Each functional genomic level shows clear growth-rate-associated trends and discriminates between carbon-sufficient and carbon-limited conditions. Genes consistently and significantly upregulated with increasing growth rate are frequently essential and encode evolutionarily conserved proteins of known function that participate in many protein-protein interactions. In contrast, more unknown, and fewer essential, genes are downregulated with increasing growth rate; their protein products rarely interact with one another. A large proportion of yeast genes under positive growth-rate control share orthologs with other eukaryotes, including humans. Significantly, transcription of genes encoding components of the TOR complex (a major controller of eukaryotic cell growth) is not subject to growth-rate regulation. Moreover, integrative studies reveal the extent and importance of post-transcriptional control, patterns of control of metabolic fluxes at the level of enzyme synthesis, and the relevance of specific enzymatic reactions in the control of metabolic fluxes during cell growth. This work constitutes a first comprehensive systems biology study on growth-rate control in the eukaryotic cell. The results have direct implications for advanced studies on cell growth, in vivo regulation of metabolic fluxes for comprehensive metabolic engineering, and for the design of genome-scale systems biology models of the

Growth control of the eukaryote cell: a systems biology study in yeast

PubMed Central

Castrillo, Juan I; Zeef, Leo A; Hoyle, David C; Zhang, Nianshu; Hayes, Andrew; Gardner, David CJ; Cornell, Michael J; Petty, June; Hakes, Luke; Wardleworth, Leanne; Rash, Bharat; Brown, Marie; Dunn, Warwick B; Broadhurst, David; O'Donoghue, Kerry; Hester, Svenja S; Dunkley, Tom PJ; Hart, Sarah R; Swainston, Neil; Li, Peter; Gaskell, Simon J; Paton, Norman W; Lilley, Kathryn S; Kell, Douglas B; Oliver, Stephen G

2007-01-01

Background Cell growth underlies many key cellular and developmental processes, yet a limited number of studies have been carried out on cell-growth regulation. Comprehensive studies at the transcriptional, proteomic and metabolic levels under defined controlled conditions are currently lacking. Results Metabolic control analysis is being exploited in a systems biology study of the eukaryotic cell. Using chemostat culture, we have measured the impact of changes in flux (growth rate) on the transcriptome, proteome, endometabolome and exometabolome of the yeast Saccharomyces cerevisiae. Each functional genomic level shows clear growth-rate-associated trends and discriminates between carbon-sufficient and carbon-limited conditions. Genes consistently and significantly upregulated with increasing growth rate are frequently essential and encode evolutionarily conserved proteins of known function that participate in many protein-protein interactions. In contrast, more unknown, and fewer essential, genes are downregulated with increasing growth rate; their protein products rarely interact with one another. A large proportion of yeast genes under positive growth-rate control share orthologs with other eukaryotes, including humans. Significantly, transcription of genes encoding components of the TOR complex (a major controller of eukaryotic cell growth) is not subject to growth-rate regulation. Moreover, integrative studies reveal the extent and importance of post-transcriptional control, patterns of control of metabolic fluxes at the level of enzyme synthesis, and the relevance of specific enzymatic reactions in the control of metabolic fluxes during cell growth. Conclusion This work constitutes a first comprehensive systems biology study on growth-rate control in the eukaryotic cell. The results have direct implications for advanced studies on cell growth, in vivo regulation of metabolic fluxes for comprehensive metabolic engineering, and for the design of genome

CREG1 enhances p16INK4a-induced cellular senescence

PubMed Central

Moolmuang, Benchamart

2011-01-01

Cellular senescence is an irreversible growth arrest that is activated in normal cells upon shortening of telomere and other cellular stresses. Bypassing cellular senescence is a necessary step for cells to become immortal during oncogenic transformation. During the spontaneous immortalization of Li-Fraumeni Syndrome (LFS) fibroblasts, we found that CREG1 (Cellular Repressor of E1A-stimulated Genes 1) expression was decreased during immortalization and increased in senescence. Moreover, we found that repression of CREG1 expression occurs via an epigenetic mechanism, promoter DNA methylation. Ectopic expression of CREG1 in the immortal LFS cell lines decreases cell proliferation but does not directly induce senescence. We confirmed this in osteosarcoma and fibrosarcoma cancer cell lines, cancers commonly seen in Li-Fraumeni Syndrome. In addition, we found that p16INK4a is also downregulated in immortal cells and that coexpression of CREG1 and p16INK4a, an inhibitor of CDK4/6 and Rb phosphorylation, has a greater effect than either CREG1 and p16INK4a alone to reduce cell growth, induce cell cycle arrest and cellular senescence in immortal LFS fibroblasts, osteosarcoma and fibrosarcoma cell lines. Moreover, cooperation of CREG1 and p16INK4a inhibits the expression of cyclin A and cyclin B by inhibiting promoter activity, thereby decreasing mRNA and protein levels; these proteins are required for S-phase entry and G2/M transition. In conclusion, this is the first evidence to demonstrate that CREG1 enhances p16INK4a-induced senescence by transcriptional repression of cell cycle-regulated genes. PMID:21263217

Large-area snow-like MoSe2 monolayers: synthesis, growth mechanism, and efficient electrocatalyst application.

PubMed

Huang, Jingwen; Liu, Huiqiang; Jin, Bo; Liu, Min; Zhang, Qingchun; Luo, Liqiong; Chu, Shijin; Chu, Sheng; Peng, Rufang

2017-07-07

This study explores the large-area synthesis of controllable morphology, uniform, and high-quality monolayer. MoSe 2 is essential for its potential application in optoelectronics, photocatalysis, and renewable energy sources. In this study, we successfully synthesized snow-like MoSe 2 monolayers using a simple chemical vapor deposition method. Results reveal that snow-like MoSe 2 is a single crystal with a hexagonal structure, a thickness of ∼0.9 nm, and a lateral dimension of up to 20 μm. The peak position of the photoluminescence spectra is ∼1.52 eV corresponding to MoSe 2 monolayer. The growth mechanism of the snow-like MoSe 2 monolayer was investigated and comprised a four-step process during growth. Finally, we demonstrate that the snow-like MoSe 2 monolayers are ideal electrocatalysts for hydrogen evolution reactions (HERs), reflected by a low Tafel slope of ∼68 mV/decade. Compared with the triangular-shaped MoSe 2 monolayer, the hexangular snow-like shape with plentiful edges is superior for perfect electrocatalysts for HERs or transmission devices of optoelectronic signals.

Role of G protein-coupled estrogen receptor-1 in estradiol 17β-induced alterations in protein synthesis and protein degradation rates in fused bovine satellite cell cultures.

PubMed

Kamanga-Sollo, E; Thornton, K J; White, M E; Dayton, W R

2017-01-01

In feedlot steers, estradiol-17β (E2) and combined E2 and trenbolone acetate (a testosterone analog) implants enhance rate and efficiency of muscle growth; and, consequently, these compounds are widely used as growth promoters in several countries. Treatment with E2 stimulates protein synthesis rate and suppresses protein degradation rate in fused bovine satellite cell (BSC) cultures; however, the mechanisms involved in these effects are not known with certainty. Although the genomic effects of E2 mediated through the classical estrogen receptors have been characterized, recent studies indicate that binding of E2 to the G protein-coupled estrogen receptor (GPER)-1 mediates nongenomic effects of E2 on cellular function. Our current data show that inhibition of GPER-1, matrix metalloproteinases 2 and 9 (MMP2/9), or heparin binding epidermal growth factor-like growth factor (hbEGF) suppresses E2 stimulate protein synthesis rate in cultured BSCs (P < 0.001) suggesting that all of these are required in order for E2 to stimulate protein synthesis in these cultures. In contrast, inhibition of GPER-1, MMP2/9, or hbEGF has no effect on the ability of E2 to suppress protein degradation rates in fused BSC cultures indicating that these factors are not required in order for E2 to suppress protein degradation rate in these cells. Furthermore, treatment of fused BSC cultures with E2 increased (P < 0.05) pAKT levels indicating that the pAKT pathway may play a role in E2-stimulated effects on cultured BSC. In summary, our current data show that active GPER-1, MMP2/9, and hbEGF are necessary for E2-stimulated protein synthesis but not for E2-simulated suppression of protein degradation in cultured BSC. In addition, E2 treatment increases pAKT levels in cultured BSC. Copyright © 2016 Elsevier Inc. All rights reserved.

Mutants of Escherichia coli defective in membrane phospholipid synthesis: macromolecular synthesis in an sn-glycerol 3-phosphate acyltransferase Km mutant.

PubMed

Bell, R M

1974-03-01

sn-Glycerol 3-phosphate (G3P) auxotrophs of Escherichia coli have been selected from a strain which cannot aerobically catabolize G3P. The auxotrophy resulted from loss of the biosynthetic G3P dehydrogenase (EC 1.1.1.8) or from a defective membranous G3P acyltransferase. The apparent K(m) of the acyltransferase for G3P was 11- to 14-fold higher (from about 90 mum to 1,000 to 1,250 mum) in membrane preparations from the mutants than those of the parent. All extracts prepared from revertants of the G3P dehydrogenase mutants showed G3P dehydrogenase activity, but most contained less than 10% of the wild-type level. Membrane preparations from revertants of the acyltransferase mutants had apparent K(m)'s for G3P similar to that of the parent. Strains have been derived in which the G3P requirement can be satisfied with glycerol in the presence of glucose, presumably because the glycerol kinase was desensitized to inhibition by fructose 1,6-diphosphate. Investigations on the growth and macromolecular synthesis in a G3P acyltransferase K(m) mutant revealed that upon glycerol deprivation, net phospholipid synthesis stopped immediately; growth continued for about one doubling; net ribonucleic acid (RNA), deoxyribonucleic acid (DNA), and protein nearly doubled paralleling the growth curve; the rate of phospholipid synthesis assessed by labeling cells with (32)P-phosphate, (14)C-acetate, or (3)H-serine was reduced greater than 90%; the rates of RNA and DNA synthesis increased as the cells grew and then decreased as the cells stopped growing; the rate of protein synthesis showed no increase and declined more slowly than the rates of RNA and DNA synthesis when the cells stopped growing. The cells retained and gained in the capacity to synthesize phospholipids upon glycerol deprivation. These data indicate that net phospholipid synthesis is not required for continued macromolecular synthesis for about one doubling, and that the rates of these processes are not coupled during this

Oscillating-Crucible Technique for Silicon Growth

NASA Technical Reports Server (NTRS)

Daud, T.; Dumas, K. A.; Kim, K. M.; Schwuttke, G. H.; Smetana, P.

1984-01-01

Technique yields better mixing of impurities and superior qualiity crystals. Accellerated motion stirs melt which reduces temperature gradients and decreases boundary layer for diffusion of impurities near growing surface. Results better mixing of impurities into melt, decrease in tendency for dendritic growth or cellular growth and crystals with low dislocation density. Applied with success to solution growth and Czochralski growth, resulting in large crystals of superior quality.

Involvement of H- and N-Ras isoforms in transforming growth factor-{beta}1-induced proliferation and in collagen and fibronectin synthesis

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

Martinez-Salgado, Carlos; Fuentes-Calvo, Isabel; Instituto 'Reina Sofia' de Investigacion Nefrologica, Universidad de Salamanca, 37007 Salamanca

2006-07-01

Transforming growth factor {beta}1 (TGF-{beta}1) has a relevant role in the origin and maintenance of glomerulosclerosis and tubule-interstitial fibrosis. TGF-{beta} and Ras signaling pathways are closely related: TGF-{beta}1 overcomes Ras mitogenic effects and Ras counteracts TGF-{beta} signaling. Tubule-interstitial fibrosis is associated to increases in Ras, Erk, and Akt activation in a renal fibrosis model. We study the role of N- and H-Ras isoforms, and the involvement of the Ras effectors Erk and Akt, in TGF-{beta}1-mediated extracellular matrix (ECM) synthesis and proliferation, using embrionary fibroblasts from double knockout (KO) mice for H- and N-Ras (H-ras {sup -/-}/N-ras {sup -/-}) isoforms andmore » from heterozygote mice (H-ras {sup +/-}/N-ras {sup +/-}). ECM synthesis is increased in basal conditions in H-ras {sup -/-}/N-ras {sup -/-} fibroblasts, this increase being higher after stimulation with TGF-{beta}1. TGF-{beta}1-induced fibroblast proliferation is smaller in H-ras {sup -/-}/N-ras {sup -/-} than in H-ras {sup +/-}/N-ras {sup +/-} fibroblasts. Erk activation is decreased in H-ras {sup -/-}/N-ras {sup -/-} fibroblasts; inhibition of Erk activation reduces fibroblast proliferation. Akt activation is higher in double KO fibroblasts than in heterozygotes; inhibition of Akt activation also inhibits ECM synthesis. We suggest that H- and N-Ras isoforms downregulate ECM synthesis, and mediate proliferation, in part through MEK/Erk activation. PI3K-Akt pathway activation may be involved in the increase in ECM synthesis observed in the absence of H- and N-Ras.« less

Arctigenin induced gallbladder cancer senescence through modulating epidermal growth factor receptor pathway.

PubMed

Zhang, Mingdi; Cai, Shizhong; Zuo, Bin; Gong, Wei; Tang, Zhaohui; Zhou, Di; Weng, Mingzhe; Qin, Yiyu; Wang, Shouhua; Liu, Jun; Ma, Fei; Quan, Zhiwei

2017-05-01

Gallbladder cancer has poor prognosis and limited therapeutic options. Arctigenin, a representative dibenzylbutyrolactone lignan, occurs in a variety of plants. However, the molecular mechanisms involved in the antitumor effect of arctigenin on gallbladder cancer have not been fully elucidated. The expression levels of epidermal growth factor receptor were examined in 100 matched pairs of gallbladder cancer tissues. A positive correlation between high epidermal growth factor receptor expression levels and poor prognosis was observed in gallbladder cancer tissues. Pharmacological inhibition or inhibition via RNA interference of epidermal growth factor receptor induced cellular senescence in gallbladder cancer cells. The antitumor effect of arctigenin on gallbladder cancer cells was primarily achieved by inducing cellular senescence. In gallbladder cancer cells treated with arctigenin, the expression level of epidermal growth factor receptor significantly decreased. The analysis of the activity of the kinases downstream of epidermal growth factor receptor revealed that the RAF-MEK-ERK signaling pathway was significantly inhibited. Furthermore, the cellular senescence induced by arctigenin could be reverted by pcDNA-epidermal growth factor receptor. Arctigenin also potently inhibited the growth of tumor xenografts, which was accompanied by the downregulation of epidermal growth factor receptor and induction of senescence. This study demonstrates arctigenin could induce cellular senescence in gallbladder cancer through the modulation of epidermal growth factor receptor pathway. These data identify epidermal growth factor receptor as a key regulator in arctigenin-induced gallbladder cancer senescence.

TIF-IA, the factor mediating growth-dependent control of ribosomal RNA synthesis, is the mammalian homolog of yeast Rrn3p.

PubMed

Bodem, J; Dobreva, G; Hoffmann-Rohrer, U; Iben, S; Zentgraf, H; Delius, H; Vingron, M; Grummt, I

2000-08-01

Cells carefully modulate the rate of rRNA transcription in order to prevent an overinvestment in ribosome synthesis under less favorable nutritional conditions. In mammals, growth-dependent regulation of RNA polymerase I (Pol I) transcription is mediated by TIF-IA, an essential initiation factor that is active in extracts from growing but not starved or cycloheximide-treated mammalian cells. Here we report the molecular cloning and functional characterization of recombinant TIF-IA, which turns out to be the mammalian homolog of the yeast factor Rrn3p. We demonstrate that TIF-IA interacts with Pol I in the absence of template DNA, augments Pol I transcription in vivo and rescues transcription in extracts from growth-arrested cells in vitro.

Investigation on preferably oriented abnormal growth of CdSe nanorods along (0002) plane synthesized by henna leaf extract-mediated green synthesis

NASA Astrophysics Data System (ADS)

Iyyappa Rajan, P.; Judith Vijaya, J.; Jesudoss, S. K.; Kaviyarasu, K.; Lee, Seung-Cheol; John Kennedy, L.; Jothiramalingam, R.; Al-Lohedan, Hamad A.; Mahamad Abdullah, M.

2018-03-01

The theme of this work is to highlight the significance of green plant extracts in the synthesis of nanostructures. In asserting this statement, herein, we report our obtained results on the synthesis of hexagonal CdSe nanorods preferably oriented along (0002) plane through henna leaf extract-mediated reaction along with a discussion about the structural, morphological and optical properties of the synthesized nanorods. The possible mechanism for the synthesis of CdSe nanorods was explored. The formation of nanorods along (0002) plane was confirmed by the relatively high intensity of the (0002) peak in X-ray diffraction pattern. To account for the experimentally realistic condition, we have calculated the surface energies of hexagonal CdSe surface slabs along the low indexed (0002), (10 1 ¯ 0 ) and (11 2 ¯ 0 ) plane surfaces using density functional theory approach and the calculated surface energy value for (0002) surface is 802.7 mJ m-2, which is higher than (11 2 ¯ 0 ) and (10 1 ¯ 0 ) surfaces. On realizing the calculated surface energies of these slabs, we determined that the combination of (11 2 ¯ 0 ) and (10 1 ¯ 0 ) planes with lower surface energies will lead to the formation of CdSe nanorods growth along (0002) orientation. Finally, we argue that the design of new greener route for the synthesis of novel functional nanomaterials is highly desired.

Epitaxial growth of hybrid nanostructures

NASA Astrophysics Data System (ADS)

Tan, Chaoliang; Chen, Junze; Wu, Xue-Jun; Zhang, Hua

2018-02-01

Hybrid nanostructures are a class of materials that are typically composed of two or more different components, in which each component has at least one dimension on the nanoscale. The rational design and controlled synthesis of hybrid nanostructures are of great importance in enabling the fine tuning of their properties and functions. Epitaxial growth is a promising approach to the controlled synthesis of hybrid nanostructures with desired structures, crystal phases, exposed facets and/or interfaces. This Review provides a critical summary of the state of the art in the field of epitaxial growth of hybrid nanostructures. We discuss the historical development, architectures and compositions, epitaxy methods, characterization techniques and advantages of epitaxial hybrid nanostructures. Finally, we provide insight into future research directions in this area, which include the epitaxial growth of hybrid nanostructures from a wider range of materials, the study of the underlying mechanism and determining the role of epitaxial growth in influencing the properties and application performance of hybrid nanostructures.

AMPD2 regulates GTP synthesis and is mutated in a potentially treatable neurodegenerative brainstem disorder.

PubMed

Akizu, Naiara; Cantagrel, Vincent; Schroth, Jana; Cai, Na; Vaux, Keith; McCloskey, Douglas; Naviaux, Robert K; Van Vleet, Jeremy; Fenstermaker, Ali G; Silhavy, Jennifer L; Scheliga, Judith S; Toyama, Keiko; Morisaki, Hiroko; Sonmez, Fatma M; Celep, Figen; Oraby, Azza; Zaki, Maha S; Al-Baradie, Raidah; Faqeih, Eissa A; Saleh, Mohammed A M; Spencer, Emily; Rosti, Rasim Ozgur; Scott, Eric; Nickerson, Elizabeth; Gabriel, Stacey; Morisaki, Takayuki; Holmes, Edward W; Gleeson, Joseph G

2013-08-01

Purine biosynthesis and metabolism, conserved in all living organisms, is essential for cellular energy homeostasis and nucleic acid synthesis. The de novo synthesis of purine precursors is under tight negative feedback regulation mediated by adenosine and guanine nucleotides. We describe a distinct early-onset neurodegenerative condition resulting from mutations in the adenosine monophosphate deaminase 2 gene (AMPD2). Patients have characteristic brain imaging features of pontocerebellar hypoplasia (PCH) due to loss of brainstem and cerebellar parenchyma. We found that AMPD2 plays an evolutionary conserved role in the maintenance of cellular guanine nucleotide pools by regulating the feedback inhibition of adenosine derivatives on de novo purine synthesis. AMPD2 deficiency results in defective GTP-dependent initiation of protein translation, which can be rescued by administration of purine precursors. These data suggest AMPD2-related PCH as a potentially treatable early-onset neurodegenerative disease. Copyright © 2013 Elsevier Inc. All rights reserved.

Dispersion fraction enhances cellular growth of carbon nanotube and aluminum oxide reinforced ultrahigh molecular weight polyethylene biocomposites.

PubMed

Patel, Anup Kumar; Balani, Kantesh

2015-01-01

Ultrahigh molecular weight polyethylene (UHMWPE) is widely used as bone-replacement material for articulating surfaces due to its excellent wear resistance and low coefficient of friction. But, the wear debris, generated during abrasion between mating surfaces, leads to aseptic loosening of implants. Thus, various reinforcing agents are generally utilized, which may alter the surface and biological properties of UHMWPE. In the current work, the cellular response of compression molded UHMWPE upon reinforcement of bioactive multiwalled carbon nanotubes (MWCNTs) and bioinert aluminum oxide (Al2O3) is investigated. The phase retention and stability were observed using X-ray diffraction, Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The reinforcement of MWCNTs and Al2O3 has shown to alter the wettability (from contact angle of ~88°±2° to ~118°±4°) and surface energy (from ~23.20 to ~17.75 mN/m) of composites with respect to UHMWPE, without eliciting any adverse effect on cytocompatibility for the L929 mouse fibroblast cell line. Interestingly, the cellular growth of the L929 mouse fibroblast cell line is observed to be dominated by the dispersion fraction of surface free energy (SFE). After 48 h of incubation period, a decrease in metabolic activity of MWCNT-Al2O3 reinforced composites is attributed to apatite formation that reduces the dispersion fraction of surface energy. The mineralized apatite during incubation was confirmed and quantified by energy dispersive spectroscopy and X-ray diffraction respectively. Thus, the dispersion fraction of surface free energy can be engineered to play an important role in achieving enhanced metabolic activity of the MWCNT-Al2O3 reinforced UHMWPE biopolymer composites. Copyright © 2014 Elsevier B.V. All rights reserved.

The control of translational accuracy is a determinant of healthy ageing in yeast.

PubMed

von der Haar, Tobias; Leadsham, Jane E; Sauvadet, Aimie; Tarrant, Daniel; Adam, Ilectra S; Saromi, Kofo; Laun, Peter; Rinnerthaler, Mark; Breitenbach-Koller, Hannelore; Breitenbach, Michael; Tuite, Mick F; Gourlay, Campbell W

2017-01-01

Life requires the maintenance of molecular function in the face of stochastic processes that tend to adversely affect macromolecular integrity. This is particularly relevant during ageing, as many cellular functions decline with age, including growth, mitochondrial function and energy metabolism. Protein synthesis must deliver functional proteins at all times, implying that the effects of protein synthesis errors like amino acid misincorporation and stop-codon read-through must be minimized during ageing. Here we show that loss of translational accuracy accelerates the loss of viability in stationary phase yeast. Since reduced translational accuracy also reduces the folding competence of at least some proteins, we hypothesize that negative interactions between translational errors and age-related protein damage together overwhelm the cellular chaperone network. We further show that multiple cellular signalling networks control basal error rates in yeast cells, including a ROS signal controlled by mitochondrial activity, and the Ras pathway. Together, our findings indicate that signalling pathways regulating growth, protein homeostasis and energy metabolism may jointly safeguard accurate protein synthesis during healthy ageing. © 2017 The Authors.

The control of translational accuracy is a determinant of healthy ageing in yeast

PubMed Central

Leadsham, Jane E.; Sauvadet, Aimie; Tarrant, Daniel; Adam, Ilectra S.; Saromi, Kofo; Laun, Peter; Rinnerthaler, Mark; Breitenbach-Koller, Hannelore; Breitenbach, Michael; Tuite, Mick F.; Gourlay, Campbell W.

2017-01-01

Life requires the maintenance of molecular function in the face of stochastic processes that tend to adversely affect macromolecular integrity. This is particularly relevant during ageing, as many cellular functions decline with age, including growth, mitochondrial function and energy metabolism. Protein synthesis must deliver functional proteins at all times, implying that the effects of protein synthesis errors like amino acid misincorporation and stop-codon read-through must be minimized during ageing. Here we show that loss of translational accuracy accelerates the loss of viability in stationary phase yeast. Since reduced translational accuracy also reduces the folding competence of at least some proteins, we hypothesize that negative interactions between translational errors and age-related protein damage together overwhelm the cellular chaperone network. We further show that multiple cellular signalling networks control basal error rates in yeast cells, including a ROS signal controlled by mitochondrial activity, and the Ras pathway. Together, our findings indicate that signalling pathways regulating growth, protein homeostasis and energy metabolism may jointly safeguard accurate protein synthesis during healthy ageing. PMID:28100667

Tunable synthesis and in situ growth of silicon-carbon mesostructures using impermeable plasma.

PubMed

Yaghoubi, Alireza; Mélinon, Patrice

2013-01-01

In recent years, plasma-assisted synthesis has been extensively used in large scale production of functional nano- and micro-scale materials for numerous applications in optoelectronics, photonics, plasmonics, magnetism and drug delivery, however systematic formation of these minuscule structures has remained a challenge. Here we demonstrate a new method to closely manipulate mesostructures in terms of size, composition and morphology by controlling permeability at the boundaries of an impermeable plasma surrounded by a blanket of neutrals. In situ and rapid growth of thin films in the core region due to ion screening is among other benefits of our method. Similarly we can take advantage of exceptional properties of plasma to control the morphology of the as deposited nanostructures. Probing the plasma at boundaries by means of observing the nanostructures, further provides interesting insights into the behaviour of gas-insulated plasmas with possible implications on efficacy of viscous heating and non-magnetic confinement.

Tunable synthesis and in situ growth of silicon-carbon mesostructures using impermeable plasma

PubMed Central

Yaghoubi, Alireza; Mélinon, Patrice

2013-01-01

In recent years, plasma-assisted synthesis has been extensively used in large scale production of functional nano- and micro-scale materials for numerous applications in optoelectronics, photonics, plasmonics, magnetism and drug delivery, however systematic formation of these minuscule structures has remained a challenge. Here we demonstrate a new method to closely manipulate mesostructures in terms of size, composition and morphology by controlling permeability at the boundaries of an impermeable plasma surrounded by a blanket of neutrals. In situ and rapid growth of thin films in the core region due to ion screening is among other benefits of our method. Similarly we can take advantage of exceptional properties of plasma to control the morphology of the as deposited nanostructures. Probing the plasma at boundaries by means of observing the nanostructures, further provides interesting insights into the behaviour of gas-insulated plasmas with possible implications on efficacy of viscous heating and non-magnetic confinement. PMID:23330064

Green Synthesis of Robust, Biocompatible Silver Nanoparticles Using Garlic Extract

PubMed Central

Von White, Gregory; Kerscher, Petra; Brown, Ryan M.; Morella, Jacob D.; McAllister, William; Dean, Delphine; Kitchens, Christopher L.

2012-01-01

This paper details a facile approach for the synthesis of stable and monodisperse silver nanoparticles performed at ambient/low temperature where Allium sativum (garlic) extract functions as the silver salt reducing agent during nanoparticle synthesis as well as the post-synthesis stabilizing ligands. Varying the synthesis conditions provides control of particle size, size-distribution, and kinetics of particle formation. Infrared spectroscopy, energy dispersive x-ray chemical analysis, and high performance liquid chromatography indicated that the carbohydrates present in the garlic extract are the most likely nanoparticle stabilizing chemistry. The synthesized silver nanoparticles also demonstrate potential for biomeical applications, owing to the 1) enhanced stability in biological media, 2) resistance to oxidation by the addition of H2O2, 3) ease and scalability of synthesis, and 4) lack of harsh chemicals required for synthesis. Cytotoxicity assays indicated no decrease in cellular proliferation for vascular smooth muscle cells and 3T3 fibroblasts at a concentration of 25 μg/ml, confirming that garlic extract prepared silver nanoparticles are ideal candidates for future experimentation and implementation into biomedical applications. PMID:24683414

Green Synthesis of Robust, Biocompatible Silver Nanoparticles Using Garlic Extract.

PubMed

Von White, Gregory; Kerscher, Petra; Brown, Ryan M; Morella, Jacob D; McAllister, William; Dean, Delphine; Kitchens, Christopher L

2012-01-01

This paper details a facile approach for the synthesis of stable and monodisperse silver nanoparticles performed at ambient/low temperature where Allium sativum (garlic) extract functions as the silver salt reducing agent during nanoparticle synthesis as well as the post-synthesis stabilizing ligands. Varying the synthesis conditions provides control of particle size, size-distribution, and kinetics of particle formation. Infrared spectroscopy, energy dispersive x-ray chemical analysis, and high performance liquid chromatography indicated that the carbohydrates present in the garlic extract are the most likely nanoparticle stabilizing chemistry. The synthesized silver nanoparticles also demonstrate potential for biomeical applications, owing to the 1) enhanced stability in biological media, 2) resistance to oxidation by the addition of H 2 O 2 , 3) ease and scalability of synthesis, and 4) lack of harsh chemicals required for synthesis. Cytotoxicity assays indicated no decrease in cellular proliferation for vascular smooth muscle cells and 3T3 fibroblasts at a concentration of 25 μg/ml, confirming that garlic extract prepared silver nanoparticles are ideal candidates for future experimentation and implementation into biomedical applications.

Oscillatory cellular patterns in three-dimensional directional solidification

DOE PAGES

Tourret, D.; Debierre, J. -M.; Song, Y.; ...

2015-09-11

We present a phase-field study of oscillatory breathing modes observed during the solidification of three-dimensional cellular arrays in micro-gravity. Directional solidification experiments conducted onboard the International Space Station have allowed for the first time to observe spatially extended homogeneous arrays of cells and dendrites while minimizing the amount of gravity-induced convection in the liquid. In situ observations of transparent alloys have revealed the existence, over a narrow range of control parameters, of oscillations in cellular arrays with a period ranging from about 25 to 125 minutes. Cellular patterns are spatially disordered, and the oscillations of individual cells are spatiotemporally uncorrelatedmore » at long distance. However, in regions displaying short-range spatial ordering, groups of cells can synchronize into oscillatory breathing modes. Quantitative phase-field simulations show that the oscillatory behavior of cells in this regime is linked to a stability limit of the spacing in hexagonal cellular array structures. For relatively high cellular front undercooling (\\ie low growth velocity or high thermal gradient), a gap appears in the otherwise continuous range of stable array spacings. Close to this gap, a sustained oscillatory regime appears with a period that compares quantitatively well with experiment. For control parameters where this gap exist, oscillations typically occur for spacings at the edge of the gap. However, after a change of growth conditions, oscillations can also occur for nearby values of control parameters where this gap just closes and a continuous range of spacings exists. In addition, sustained oscillations at to the opening of this stable gap exhibit a slow periodic modulation of the phase-shift among cells with a slower period of several hours. While long-range coherence of breathing modes can be achieved in simulations for a perfect spatial arrangement of cells as initial condition, global

Oscillatory cellular patterns in three-dimensional directional solidification

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

Tourret, D.; Debierre, J. -M.; Song, Y.

We present a phase-field study of oscillatory breathing modes observed during the solidification of three-dimensional cellular arrays in micro-gravity. Directional solidification experiments conducted onboard the International Space Station have allowed for the first time to observe spatially extended homogeneous arrays of cells and dendrites while minimizing the amount of gravity-induced convection in the liquid. In situ observations of transparent alloys have revealed the existence, over a narrow range of control parameters, of oscillations in cellular arrays with a period ranging from about 25 to 125 minutes. Cellular patterns are spatially disordered, and the oscillations of individual cells are spatiotemporally uncorrelatedmore » at long distance. However, in regions displaying short-range spatial ordering, groups of cells can synchronize into oscillatory breathing modes. Quantitative phase-field simulations show that the oscillatory behavior of cells in this regime is linked to a stability limit of the spacing in hexagonal cellular array structures. For relatively high cellular front undercooling (\\ie low growth velocity or high thermal gradient), a gap appears in the otherwise continuous range of stable array spacings. Close to this gap, a sustained oscillatory regime appears with a period that compares quantitatively well with experiment. For control parameters where this gap exist, oscillations typically occur for spacings at the edge of the gap. However, after a change of growth conditions, oscillations can also occur for nearby values of control parameters where this gap just closes and a continuous range of spacings exists. In addition, sustained oscillations at to the opening of this stable gap exhibit a slow periodic modulation of the phase-shift among cells with a slower period of several hours. While long-range coherence of breathing modes can be achieved in simulations for a perfect spatial arrangement of cells as initial condition, global

Finite element design for the HPHT synthesis of diamond

NASA Astrophysics Data System (ADS)

Li, Rui; Ding, Mingming; Shi, Tongfei

2018-06-01

The finite element method is used to simulate the steady-state temperature field in diamond synthesis cell. The 2D and 3D models of the China-type cubic press with large deformation of the synthesis cell was established successfully, which has been verified by situ measurements of synthesis cell. The assembly design, component design and process design for the HPHT synthesis of diamond based on the finite element simulation were presented one by one. The temperature field in a high-pressure synthetic cavity for diamond production is optimized by adjusting the cavity assembly. A series of analysis about the influence of the pressure media parameters on the temperature field are examined through adjusting the model parameters. Furthermore, the formation mechanism of wasteland was studied in detail. It indicates that the wasteland is inevitably exists in the synthesis sample, the distribution of growth region of the diamond with hex-octahedral is move to the center of the synthesis sample from near the heater as the power increasing, and the growth conditions of high quality diamond is locating at the center of the synthesis sample. These works can offer suggestion and advice to the development and optimization of a diamond production process.

Influence of beam shape on in-vitro cellular transformations in human skin fibroblasts

NASA Astrophysics Data System (ADS)

Mthunzi, Patience; Forbes, Andrew; Hawkins, Denise; Abrahamse, Heidi; Karsten, Aletta E.

2005-08-01

A variety of strategies have been utilised for prevention and treatment of chronic wounds such as leg ulcers, diabetic foot ulcers and pressure sores1. Low Level Laser Therapy (LLLT) has been reported to be an invaluable tool in the enhancement of wound healing through stimulating cell proliferation, accelerating collagen synthesis and increasing ATP synthesis in mitochondria to name but a few2. This study focused on an in-vitro analysis of the cellular responses induced by treatment with three different laser beam profiles namely, the Gaussian (G), Super Gaussian (SG) and Truncated Gaussian (TG), on normal wounded irradiated (WI) and wounded non-irradiated (WNI) human skin fibroblast cells (WS1), to test their influence in wound healing at 632.8 nm using a helium neon (HeNe) laser. For each beam profile, measurements were made using average energy densities over the sample ranging from 0.2 to 1 J, with single exposures on normal wounded cells. The cells were subjected to different post irradiation incubation periods, ranging from 0 to 24 hours to evaluate the duration (time) dependent effects resulting from laser irradiation. The promoted cellular alterations were measured by increase in cell viability, cell proliferation and cytotoxicity. The results obtained showed that treatment with the G compared to the SG and TG beams resulted in a marked increase in cell viability and proliferation. The data also showed that when cells undergo laser irradiation some cellular processes are driven by the peak energy density rather than the energy of the laser beam. We show that there exist threshold values for damage, and suggest optimal operating regimes for laser based wound healing.

Cell-free synthesis of functional human epidermal growth factor receptor: Investigation of ligand-independent dimerization in Sf21 microsomal membranes using non-canonical amino acids