Some genetic aspects of senescence and the effects that irradiation may have in accelerating life-shortening are considered. Topics discussed include factors associated with spontaneous senescence, inheritance patterns, developmental sequences, somatic mutations and crossing over, chromosome breakage, ...
Energy Citations Database
The studies presented in the review indicate that perinatal exposure of the fetal or neonatal rodent to a toxicant can adversely affect reproductive development, reduce fertility and accelerate reproductive senescence. In rodents and humans exposure to DE...
National Technical Information Service (NTIS)
Leaf senescence, which constitutes the final stage of leaf development, involves programmed cell death and is intricately regulated by various internal and environmental signals that are incorporated with age-related information. ABA plays diverse and important physiological roles in plants, and is involved in various developmental events and stress ...
PubMed
Petal development and senescence entails a normally irreversible process. It starts with petal expansion and pigment production, and ends with nutrient remobilization and ultimately cell death. In many species this is accompanied by petal abscission. Post-harvest stress is an important factor in limiting petal longevity in cut flowers and accelerates some ...
PubMed Central
Leaf senescence is a developmentally programmed degeneration process, which is fine tuned by a complex regulatory network for plant fitness. However, molecular regulation of leaf senescence is poorly understood, especially in rice (Oryza sativa), an important staple crop for more than half of the world population. Here, we report a ...
The studies presented in this review indicate that perinatal exposure of the fetal or neonatal rodent to a toxicant can adversely affect reproductive development, reduce fertility.and accelerate reproductive senescence. n rodents and humans exposure to DES, estrogens, androgens a...
EPA Science Inventory
Auxin regulates a variety of physiological and developmental processes in plants. Although auxin acts as a suppressor of leaf senescence, its exact role in this respect has not been clearly defined, aside from circumstantial evidence. It was found here that ARF2 functions in the auxin-mediated control of Arabidopsis leaf longevity, as discovered by ...
SUMMARY: Senescence is the highly regulated last developmental phase of plant organs and tissues, and is optimized to allow nutrient remobilization to surviving plant parts, such as seeds of annual crops. High leaf carbohydrate to nitrogen (C : N) ratios have been implicated in the induction or acceleration of the ...
Timing of various developmental stages including anthesis and whole-plant ('monocarpic') senescence influences yield and quality of annual crops. While a correlation between flowering/seed filling and whole-plant senescence has been observed in many annuals, it is unclear how the gene networks controlling these processes interact. ...
Timing of various developmental stages including anthesis and whole-plant (�monocarpic�) senescence influences yield and quality of annual crops. While a correlation between flowering/seed filling and whole-plant senescence has been observed in many annuals, it is unclear how the gene networks controlling these processes interact. ...
Epidemiological studies show a strong association between low birth weight and hypertension, renal, and cardiovascular disease, especially after catch-up growth. Senescence is an important contributor to the progression of chronic disease. Developmentally programmed premature senescence may be a link among low birth weight, catch-up ...
Degradation of chlorophyll (Chl) is a developmentally regulated cellular process usually related with leaf senescence and fruit ripening. In the plastid of senescing leaves, photoactive Chl is catabolized in a stepwise manor to yield fluorescent chlorophyll catabolites (FCCs). FCCs are then exported...
Technology Transfer Automated Retrieval System (TEKTRAN)
The initiation, progression, and natural variation of autumn senescence in European aspen (Populus tremula) was investigated by monitoring chlorophyll degradation in (1) trees growing in natural stands and (2) cloned trees growing in a greenhouse under various light regimes. The main trigger for the initiation of autumn senescence in aspen is the ...
Senescence is a complex and highly regulated process. Leaf senescence is influenced by endogenous developmental and external environmental signals. In this work, we found that expression of an Ap2/DREB-type transcription factor gene, Arabidopsis Rap2.4f (At4g28140), was upregulated by salt, mannitol, and dark treatments. Constitutively ...
Mature indeterminate Medicago truncatula nodules are zonated with an apical meristem, an infection zone, a fixation zone with nitrogen-fixing bacteroids, and a "developmental" senescence zone that follows nodule growth with a conical front originating in the center of the fixation zone. In nitrogen-fixing cells, senescence is initiated ...
Mature indeterminate Medicago truncatula nodules are zonated with an apical meristem, an infection zone, a fixation zone with nitrogen-fixing bacteroids, and a �developmental� senescence zone that follows nodule growth with a conical front originating in the center of the fixation zone. In nitrogen-fixing cells, senescence is ...
A modest ethylene climacteric accompanies flower senescence in Mirabilis jalapa L., and exogenous ethylene accelerates the process. However, inhibitors of ethylene action and synthesis have little effect on the life-span of these ephemeral flowers. Treatment with '-amanitin, an inhibitor of DNA-de...
The senescence of detached Tropaeolum majus leaves was compared with that described earlier for Avena. Tropaeolum was chosen as being not only a dicot but also as having a nearly circular leaf, thus needing only the smallest minimum of wounding, since wounding delays the loss of chlorophyll and protein in darkness. Tropaeolum resembles Avena in that closing the stomata ...
... associated tumors as well as melanoma and pancreatic cancer cell lines. In developmental studies, Tbx2 has been shown ...
DTIC Science & Technology
Asparagus officinalis L. Garden Asparagus E FACU 0 136 Asplenium montanum Willd. Mountain Spleenwort N Kn. 8
E-print Network
BackgroundSenescence is integral to the flowering plant life-cycle. Senescence-like processes occur also in non-angiosperm land plants, algae and photosynthetic prokaryotes. Increasing numbers of genes have been assigned functions in the regulation and execution of angiosperm senescence. At the same time there has been a large ...
Nitrogen-fixing bacteroids are degraded during nodule senescence. This is in contrast to recent implications that viable bacteroids can be released into soil from legume nodules. Rhizobia originating from persistent infection threads in senescing nodule plant cells seem to be the source of viable cells required for perpetuation of the Rhizobium spp. ...
Inflammation is an underlying basis for the molecular alterations that link aging and age-related pathological processes. In a previous study, we found that secretory phospholipase A(2) (sPLA(2)) induced cellular senescence in human dermal fibroblasts (HDFs). To further investigate the association of inflammation with cellular senescence, the effects of ...
Fibroblasts derived from glucose-6-phosphate dehydrogenase (G6PD)-deficient patients display retarded growth and accelerated cellular senescence that is attributable to increased accumulation of oxidative DNA damage and increased sensitivity to oxidant-induced senescence, but not to accelerated telomere attrition. ...
... were processed and analyzed in the same manner. Analysis. Herbivore loads were expressed as psyllid feeding days (pfd) per ... ...
NBII National Biological Information Infrastructure
BackgroundCellular senescence is a major barrier to tumour progression, though its role in pathogenesis of cancer and other diseases is poorly understood in vivo. Improved understanding of the degree to which latent senescence signalling persists in tumours might identify intervention strategies to provoke "accelerated ...
Leaf senescence is a developmentally programmed degeneration process that constitutes the final step of leaf development and is controlled by multiple developmental and environmental signals. In addition to the information obtained from other plants, Arabidopsis has, as a model system, contributed to our understanding of this complex ...
Leaf senescence is a developmentally programmed cell death process that constitutes the final step of leaf development and involves the extensive reprogramming of gene expression. Despite the importance of senescence in plants, the underlying regulatory mechanisms are not well understood. This study reports the isolation and functional ...
Flower senescence is the terminal phase of developmental processes that lead to the death of flower, which include, flower wilting, shedding of flower parts and fading of blossoms. Since it is a rapid process as compared to the senescence of other parts of the plant it therefore provides excellent model system for the study of ...
Plant organs are initiated as primordial outgrowths, and require controlled cell division and differentiation to achieve their final size and shape. Superimposed on this is another developmental program that orchestrates the switch from vegetative to reproductive to senescence stages in the life cycle. These require sequential function of heterochronic ...
... be associated with either peramorphic phenomena, such as accelerated rates of ... reproductive�developmental�ecological systems that are highly ... ...
Senescence of isolated oat seedling leaves, floating on water or solutions in white light, has been followed by the disappearance of chlorophyll and the liberation of free amino nitrogen. In parallel, measurements of stomatal aperture were made with a diffusion resistance porometer, and borne out also by changes in fresh weight. The stomata open as expected in the light but ...
Considering the early phylogenetic appearance of functional xylem and phloem elements and the range of senescent processes expressed onto genetically, it becomes apparent that such processes are inextricably linked to the evolution, development, reproduction, form, and function of higher plants. The importance of these senescent processes to man are ...
Mammalian aging is thought to be partially caused by the diminished capacity of stem/precursor cells to undergo self-renewing divisions. Although many cell-cycle regulators are involved in this process, it is unknown to what extent cell senescence, first identified as irreversible growth arrest in vitro, contributes to the aging process. Here, using a serum-induced mouse ...
Senescence may be considered the antithesis of early development, but yet there may be factors and mechanisms in common between these two phenomena during the process of aging. We investigated whether any relationship exists between the regulatory mechanisms that function in early development and in senescence using the zebrafish (Danio rerio), a small ...
Leaf senescence is a genetically programmed decline in various cellular processes including photosynthesis and involves the hydrolysis of macromolecules such as proteins, lipids, etc. It is governed by the developmental age and is induced or enhanced by environmental stresses such as drought, heat, salinity and others. Internal factors such as reproductive ...
Therapy-induced accelerated cellular senescence (ACS) is a reversible tumor response to chemotherapy that is likely detrimental to the overall therapeutic efficacy of cancer treatment. To further understand the mechanism by which cancer cells can escape the sustained cell cycle arrest in ACS, we established a tissue culture model, in which the p53-null ...
BackgroundGenotoxic stress, such as by exposure to bromodeoxyuridine (BrdU) and cigarette smoke, induces premature cell senescence. Recent evidence indicates that cellular senescence of various types of cells is accelerated in COPD patients. However, whether the senescence of airway epithelial cells contributes to ...
The plant hormone ethylene is involved in many developmental processes, including fruit ripening, abscission, senescence, and leaf epinasty. Tomato contains a family of ethylene receptors, designated LeETR1, LeETR2, NR, LeETR4, and LeETR5, with homology to the Arabidopsis ETR1 ethylene receptor. Transgenic plants with reduced LeETR4 gene expression display ...
The senescence (proteolysis and loss of chlorophyll) of isolated leaves of oat seedlings in the dark is inhibited or delayed by compounds of six different types: phenazine methosulfate, fusicoccin, ?,??-dipyridyl, cycloheximide, spermidine, and two cytokinins. In every case but the last, these compounds in optimum concentration caused the stomata to open and remain partly or ...
The finite proliferative potential of normal human cells leads to replicative cellular senescence, which is a critical barrier to tumour progression in vivo1�3. We show that human p53 isoforms (?133p53 and p53?)4 constitute an endogenous regulatory mechanism for p53-mediated replicative senescence. Induced p53? and diminished ?133p53 were associated with ...
The finite proliferative potential of normal human cells leads to replicative cellular senescence, which is a critical barrier to tumour progression in vivo. We show that the human p53 isoforms Delta133p53 and p53beta function in an endogenous regulatory mechanism for p53-mediated replicative senescence. Induced p53beta and diminished Delta133p53 were ...
The elderly are prone to postprandial hyperglycemia that increases their cardiovascular risk. Although insulin therapy is necessary to treat diabetes, high plasma concentrations of insulin may cause the development of atherosclerosis and accelerate endothelial senescence. We assumed that high glucose causes stress-induced premature ...
Cellular senescence represents a powerful tumor suppressor mechanism to prevent proliferation and invasion of malignant cells. Since tumor cells as well as primary fibroblasts lacking the lysosomal cysteine-type carboxypeptidase cathepsin X exhibit a reduced invasive capacity, we hypothesized that the underlying reason may be the induction of cellular ...
Senescence is a highly orchestrated developmental stage in the life cycle of plants. The onset of senescence is tightly controlled by signaling cascades that initiate changes in gene expression and the synthesis of new proteins. This complement of new proteins includes hydrolytic enzymes capable of executing catabolism of ...
Leaf senescence is a developmentally programmed cell death process that constitutes the final step of leaf development, and it can be regulated by multiple environmental cues and endogenous signals. The mitogen-activated protein kinase (MAPK) cascades play diverse roles in intracellular and extracellular signaling in plants. Roles of the MAPK signaling ...
Arabidopsis hexokinase (AtHXK1), an enzyme that catalyses hexose phosphorylation, accelerates leaf senescence, whereas the plant hormone cytokinin inhibits senescence. Previous work in our laboratory has shown that isopentenyl transferase (IPT), a key gene in the biosynthesis of cytokinin, expressed under promoters of the ...
1. Longitudinal studies of various vertebrate populations have recently demonstrated senescent declines in reproductive performance and/or survival probability with age to be almost ubiquitous in nature. Little is known, however, about the extent to which rates of senescence vary between individuals, and about causes or consequences of such variation. ...
Recent studies have demonstrated that p21WAF1 (now known as CDKN1A)-dependent and -independent accelerated senescence responses are a major determinant of the sensitivity of cancer cells to chemotherapeutic agents. The objective of the present study was to determine whether human solid tumor-derived cell lines that express wild-type TP53 can exhibit levels ...
Manganese superoxide dismutase (MnSOD or SOD2) is a key mitochondrial enzymatic antioxidant. Arguably the most striking phenotype associated with complete loss of SOD2 in flies and mice is shortened life span. To further explore the role of SOD2 in protecting animals from aging and age-associated pathology, we generated a unique collection of Drosophila mutants that progressively reduce SOD2 ...
Although the accelerated atherosclerosis and premature aging of the cardiovascular system in patients with metabolic syndrome have been appreciated, the mechanisms of their development and potential therapeutic interventions remain unresolved. Our previous studies implicated advanced glycosylation end products in development of premature senescence ...
The decline in olfaction with age is well documented in histological, psychological, and electroencephalographical studies. However, there are few electrophysiological studies on changes in the sensitivity of the peripheral olfactory cells with age. We evaluated the behavior, the amplitude of electro-olfactogram (EOG), and the thickness of the olfactory epithelium in the ...
Evidence supporting the hypothesis that ethylene is involved in the control of senescence and abscission is reviewed. The data indicate that ethylene causes abscission in vivo by inhibiting auxin synthesis and transport or enhancing auxin destruction, thus lowering the diffusible auxin level. Studies with isolated leaves and explants suggest that the gas also may influence ...
... metamorphosis earlier than tadpoles kept in constant conditions. Acceleration was not possible when food was withheld, except ... lowered and only during later developmental stages. Because acceleration o...
Leaf senescence is a highly regulated developmental process that is coordinated by several factors. Many senescence-associated genes (SAGs) have been identified, but their roles during senescence remain unclear. A sweet potato (Ipomoea batatas) SAG, named SPA15, whose function was unknown, was identified ...
*The aim of this work was to determine the genetic basis of sugar-regulated senescence and to explore the relationship with other traits, including flowering and nitrogen-use efficiency. *Quantitative trait loci (QTLs) for senescence were mapped in the Arabidopsis Bay-0 x Shahdara recombinant-inbred line (RIL) population after growth on glucose-containing ...
RESEARCH ARTICLE Age-related disruptions of circadian rhythm and memory in the senescence and circadian rhythms with a focus on the senescence-accelerated mouse (SAM) as a model of aging. We explore-Fos . circadian rhythms . mouse . running wheel . SAMP8 . suprachiasmatic nucleus Cognitive impairments are well
... of p21 in apoptosis and senescence of human colon cancer cells treated with camptothecin. J. Biol. Chem 277: ... J. Jorgensen. p21WAF1/CIP1 antisense therapy radiosensitizes human colon cancer by convertin...
A modest ethylene climacteric accompanies flower senescence in Mirabilis jalapa L., and exogenous ethylene accelerates the process. However, inhibitors of ethylene action and synthesis have little effect on the life-span of these ephemeral flowers. Treatment with a-amanitin, an inhibitor of DNA-depe...
Experiments were conducted to examine the effects of the anti-ozonant ethylenediurea (EDU) and chronic ozone (O3) exposure on leaf physiology and senescence in an O3-sensitive potato cultivar (Solanum tuberosum L. cv. Norland). A dose-response experiment showed that an EDU concentration of 15 mg l(-1) soil (given as a soil drench) provided complete protection from ...
Seasonal dynamics of total phenolics (TP), extractable condensed tannins (ECT), protein-bound condensed tannins (PBCT), fiber-bound condensed tannins (FBCT), total condensed tannins (TCT), and protein precipitation capacity (PPC) in young, mature and senescent branchlets of Casuarina equisetifolia were studied at Chishan Forestry Center of Dongshan County, Fujian Province, ...
, the nonreproductive swarmer cell differ- entiates into a sessile and reproductive stalked cell. The stalked cell, the reproductive output of stalked cells decreased at an accelerating rate with in- creasing age, indicating-trans- formed rate of reproduction on cell age indi- cated that reproductive output decreased with age (combined
... Obstetrics and Gynecology, Brown Medical School and Women & Infants Hospital, Providence, Rhode Island 02905 bLaboratory for Reproductive ... at the Marine Biological Laboratory and Women and Infants...
a transition from autotrophic to heterotrophic metabolism indicating that de novo synthesis of enzymes, which and cytokinin treatments delayed the induction of SARK transcript, while darkness and ethylene accelerated- dependent leaf senescence were identified through the interaction between age-related changes and ethylene
part of aging [18]. It may also be highly relevant to conditions of accelerated senescence, or progeria syndromes. In this regard, it is significant that patients with Hutchinson-Gilford Progeria Syndrome appear
In Arabidopsis thaliana, a family of six genes (ACBP1 to ACBP6) encodes acyl-CoA binding proteins (ACBPs). Investigations on ACBP3 reported here show its upregulation upon dark treatment and in senescing rosettes. Transgenic Arabidopsis overexpressing ACBP3 (ACBP3-OEs) displayed accelerated leaf senescence, whereas an acbp3 T-DNA ...
We describe the basic tenets of the current concepts of cancer biology, and review the recent advances on the suppressor role of senescence in tumor growth and the breakdown of this barrier during the origin of tumor growth. Senescence phenotype can be induced by (1) telomere attrition-induced senescence at the end of the cellular ...
Different parameters which vary during the leaf development in sunflower plants grown with nitrate (2 or 20 mM) for a 42-day period have been determined. The plants grown with 20 mM nitrate (N+) showed greater leaf area and specific leaf mass than the plants grown with 2 mM nitrate (N-). The total chlorophyll content decreased with leaf senescence, like the photosynthetic ...
Travelling wave linear electron accelerators (LEA) are widely used in the circuits of pulse sources and neutron selectors. Previous investigations on optimizing the parameters of waveguide accelerators of neutron sources have shown certain advantages of u...
Animal models are valuable research tools towards effective prevention of sarcopenia and towards a better understanding of the mechanisms underlying skeletal muscle aging. We investigated whether senescence-accelerated mouse (SAM) strains provide valid models for skeletal muscle aging studies. Male senescence-prone mice SAMP6 and SAMP8 were studied at age ...
CD28 costimulatory signal transduction in T lymphocytes is essential for optimal telomerase activity, stabilization of cytokine mRNAs, and glucose metabolism. During aging and chronic infection with HIV-1, there are increased proportions of CD8 T lymphocytes that lack CD28 expression and show additional features of replicative senescence. Moreover, the abundance of these cells ...
Rationale: Senescence of pulmonary artery smooth muscle cells (PA-SMCs) caused by telomere shortening or oxidative stress may contribute to pulmonary hypertension associated with chronic lung diseases. Objective: To investigate whether cell senescence contributes to pulmonary vessel remodeling and pulmonary hypertension in chronic obstructive pulmonary ...
Increased female reproductive rates usually result in accelerated senescence. This correlation provides a link between the evolutionary conflict of the sexes and aging when ejaculate components elevate female reproductive rates at the cost of future reproduction. It is not clear whether this female cost is manifest as shorter lifespan or an earlier onset ...
Mesenchymal stem cells (MSCs) are of great therapeutic potentials due to their multi-lineage differentiation capabilities. Before transplantation, in vitro culture-expansion of MSCs is necessary to get desired cell number. We observed that cell contact accelerated replicative senescence during such process. To confirm the finding as well as to investigate ...
Telomeres and their changes in length throughout the life span of cells have been intensively investigated in different organisms. Telomere length is assumed to control replicative senescence in mammalian cells. However, only very few data are available on the developmental dynamics of plant telomeres. Here, changes of telomere length and DNA-protein ...
Leaf senescence of annual plants is a genetically programmed developmental phase. The onset of leaf senescence is however not exclusively determined by tissue age but is modulated by various environmental factors. Shading of individual attached leaves evokes dark-induced senescence. The initiation and progression ...
Acceleration, which involves the reorganization of instruction and curricula in ways that facilitate the completion of academic requirements in an expedited manner, is an increasingly popular strategy at community colleges for improving the outcomes of developmental education students. This paper reviews the literature on acceleration ...
ERIC Educational Resources Information Center
Remobilization of mineral nutrients from leaves to reproductive structures is a possible regulatory factor in leaf senescence. The relationship between P remobilization from leaves of soybean (Glycine max [L.] Merr. cv McCall) during reproductive development and leaf senescence was determined by utilizing soil P treatments that supplied deficient, optimum, ...
The main symptoms of leaf senescence are the degradation of chlorophyll and proteins (which may be accompanied by ammonium accumulation), and an increase of electrolyte leakage (EL), which has been traditionally attributed to disruption of cell membranes. The aim of this study was to determine if ammonium efflux contributes to the increase EL in senescing ...
The insulin-like growth factor (IGF) signaling pathway plays a crucial role in the regulation of cell growth, differentiation, apoptosis, and aging. IGF-binding proteins (IGFBPs) are important members of the IGF axis. IGFBP-5 is up-regulated during cellular senescence in human dermal fibroblasts and endothelial cells, but the function of IGFBP-5 in cellular ...
Cellular senescence, being the result of serial subculturing or of exogenous stresses, is considered to be a potent anticancer mechanism. However, it has been proposed that senescent cells may enhance the growth of adjacent malignant epithelial cells. On the other hand, exposure of tumors to repeated low doses of ?-irradiation is a common treatment regime. ...
