Transcriptomic evidence for a trade-off between germline proliferation and immunity inDrosophila

Abstract

Life-history theory posits that investment into reproduction might occur at the expense of investment into somatic maintenance, including immune function. If so, reduced or curtailed reproductive effort might be expected to increase immunity. In support of this notion, work in Caenorhabditis elegans has shown that worms lacking a germline exhibit improved immunity, but whether the antagonistic relation between germline proliferation and immunity also holds for other organisms is less well understood. Here, we report that transgenic ablation of germ cells in late development or early adulthood in Drosophila melanogaster causes elevated baseline expression and increased induction of Toll and Imd immune genes upon bacterial infection, as compared to fertile flieswith an intact germline. We also identify immune genes whose expression after infection differs between fertile and germline-less flies in a manner that is conditional on their mating status. We conclude that germline activity strongly impedes the expression and inducibility of immune genes and that this physiological trade-off might be evolutionarily conserved.

Fertility decline inAedesmosquitoes is associated with reduced maternal transcript deposition and does not depend on female age

“…Female mosquitoes’ reproductive output has been positively correlated with nutritional reserves during the previtellogenic resting stage of oogenesis [56,57]. Fertility and fitness have been linked in insects, particularly in regards to immunity [58,59]. Artificial selection experiments in Drosophila showed that selecting for increased lifespan extends adult survivorship but decreased early reproduction and vise-versa [60].…”

Inherent constraints on a polyfunctional tissue lead to a reproduction-immunity tradeoff

“…Additionally, we observed transcriptional signatures of ER stress in the MI females, consistent with a previous report that described ER stress upon infection in D. melanogaster [ 29 ]. Previous studies that used whole flies to interrogate the transcriptional response to mating (e.g., [ 28 , 30 ]) or infection (e.g., [ 10 ]) have not highlighted ribogenesis genes as a category that change expression substantially in response to infection. A probable explanation may be that the suppressed ribogenesis occurs primarily in the fat body and is masked in samples derived from whole flies.…”

Effect of larval diet on adult immune function is contingent upon selection history and host sex inDrosophila melanogaster

“…This can potentially free up resources, that would otherwise have been invested in oogenesis, and even in times of resource scarcity, help maintain other organismal functions (such as immune function) at their optimal levels. Ablation of germline, and therefore the resource sink , has been previously shown to improve immune function in flies (Short et al 2012, Rodrigues et al 2021)…”