مقاومت در برابر استرس و طول عمر در خطوط انتخاب شده از مگس سرکه
|کد مقاله||سال انتشار||مقاله انگلیسی||ترجمه فارسی||تعداد کلمات|
|37867||1999||9 صفحه PDF||سفارش دهید||6543 کلمه|
Publisher : Elsevier - Science Direct (الزویر - ساینس دایرکت)
Journal : Neurobiology of Aging, Volume 20, Issue 5, September–October 1999, Pages 521–529
Five independent populations (lines) of Drosophila melanogaster were selected for female starvation resistance. Females and males from the selected lines were relatively starvation resistant when compared to flies from five control lines. Moreover, flies from selected lines were resistant to other stresses: desiccation, acetone fumes, ethanol fumes, and paraquat (a source of oxygen radicals). Data from a variety of previous studies indicate an association between stress resistance and longevity. In this context, the present study addressed the question of whether flies from the stress-resistant lines were relatively long-lived. Replicate population cages from each selected and control line were used to assess longevity. Neither females nor males from the selected lines were relatively long-lived. In at least some cases, stress resistance may be necessary, but not sufficient, for longevity.
A body of data suggest an association between stress resistance and longevity. Support for a genetic basis for this relationship is derived from selection experiments, mutation analysis, and studies of differential gene expression. Selection experiments using Drosophila melanogaster have implicated a relationship between stress and longevity. Rose  selected for late-life reproduction, which increased longevity as a correlated response to selection. Flies from these selected lines were also found to be resistant to a variety stresses . Specifically, Males and females from the selected lines were resistant to starvation, desiccation, and vapor from 15% ethanol. Conversely, selection for desiccation resistance or starvation resistance resulted in increased longevity . Mutational analysis of longevity has been based on three model organisms: a yeast (Saccharomyces cerevisiae), a nematode (Caenorhabditis elegans) and a fly (D. melanogaster). Induced mutations in these model organisms indicate a correlation between longevity and stress resistance. For example, yeast mutations characterized by stress resistance may exhibit a longer replicative life span . A D. melanogaster P-element insertion mutation characterized by extended longevity was also relatively resistant to oxidative stress (paraquat), starvation, and high temperature . A suite of nematode genes control entry into the dauer larval state, and mutations in some of these genes confer greater longevity . Nematode mutations that increase longevity tend to be multiple-stress resistant  and . Investigation of gene expression during the aging process, and studies based on differential expression of genes by using transgenic organisms, also indicate a genetic relationship between stress resistance and longevity. Relatively old yeast show elevated expression of the RAS2 gene and, perhaps accordingly, transgenic over expression of RAS2 delays replicative senescence in yeast  and . RAS2 plays a general role in environment-mediated cell signaling and can mediate responses to nutritional status and various stresses, including starvation, exposure to ultraviolet light, heat shock, and oxidative damage  and . D. melanogaster has proven to be useful in this area of investigation. In aging muscle tissue, Wheeler et al.  documented increased expression of heat shock protein 70 (hsp70) and increased mRNA abundance of the hsp22 and hsp23 genes. Tatar et al.  determined that a transgenic strain of D. melanogaster with extra copies of the hsp70 gene exhibited an increased life span. Also in D. melanogaster, transgenic over expression of a superoxide dismutase (SOD) gene resulted in increased resistance to oxidative damage and increased life span in one study, but not in a second study  and . Simultaneous over expression of catalase and SOD apparently increased life span  and . In an inducible D. melanogaster gene expression system, catalase over-expression did not extend life span, but SOD over-expression increased life span ∼50% . Using D. melanogaster, we continue the investigation of the association between stress resistance and longevity. The current study compares five lines selected for starvation resistance with five control lines . The comparison consists of stress-resistance assays and analysis of life span. The stress assays were tests for resistance to desiccation, solvent fumes, oxidation, as well as starvation resistance. Life span was evaluated for all selected and control lines by monitoring daily mortality in population cages. The a priori hypotheses were that flies from the lines selected for starvation resistance were resistant to other stresses and that they were relatively long-lived