Extended longevity lines of Drosophila melanogaster: abundance of yolk protein gene mRNA in fat body and ovary.
Lines of Drosophila melanogaster selected for late-life female reproduction typically exhibit correlated responses of reduced early fecundity and increased longevity. This relationship suggests a tradeoff between reproductive effort and somatic maintenance, which in turn, underlies some evolutionary theories of senescence. The mechanistic basis of the apparent tradeoff between increased longevity and reduced early-age fecundity has remained obscure. The present manuscript addresses the issues of whether the reduced early-age fecundity in selected lines corresponds to reduced yolk-protein mRNA production, and whether long-lived flies exhibit somatic maintenance in terms of relatively reduced yolk-protein mRNA production in the fat body. Yolk protein is one of the most abundant proteins used for female reproduction. By comparing a set of lines selected for late life reproduction with the corresponding control lines, we show that that yolk-protein gene mRNA relative abundance during the first four days posteclosion did not correspond to reduced early-life fecundity in the selected lines. In D. melanogaster, yolk protein is produced in the fat body and ovarian follicle cells. On the fourth day posteclosion, relatively more yolk-protein gene mRNA was present in the fat body. On day 1 posteclosion, supplemental yeast did not alter relative yolk-protein gene mRNA abundance. However, on day 4 posteclosion, supplemental yeast stimulated yolk-protein gene mRNA production in the fat body, which suggests an underlying mechanism for the nutrition-based phenotypic plasticity of fecundity previously documented in these lines. On medium without supplemental yeast, the relatively low abundance of fat body yolk-protein gene mRNA in the selected lines on day 4 posteclosion corresponds to a prediction derived from the disposable soma theory.
Carlson
K A
KA
School of biological Sciences, University of Nebraska-Lincoln, 68588-0118, USA.
Harshman
L G
LG
D000375:Aging / Q000235:genetics / Q000502:physiology; D000818:Animals; D004331:Drosophila melanogaster / Q000235:genetics* / Q000502:physiology; D004527:Egg Proteins / Q000235:genetics*; D005216:Fat Body / Q000378:metabolism; D005260:Female; D005298:Fertility / Q000235:genetics / Q000502:physiology; D008136:Longevity / Q000235:genetics* / Q000502:physiology; D010053:Ovary / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
D004527:Egg Proteins; D012333:RNA, Messenger