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Al-Saadi, R. S.

Publications and source records attributed to Al-Saadi, R. S..

3 recordsLinked to original sources

Disruption of the insulin signaling pathway in C. elegans dramatically increases male longevity and enhances reproductive health late in life

Males and females are known to have dramatically different health and lifespan trajectories, but the underlying basis for these differences is only now being fully investigated1. In the Caenorhabditis elegans nematode model system, most aging studies have been conducted with hermaphrodites, and little is known about male-specific responses to pro-longevity mutations. Several previous studies have used the auxin-inducible degron system to degrade the insulin-like DAF-2/IGF-1 receptor in hermaphrodites, finding that both ubiquitous and tissue-specific degradation can extend lifespan2-4. Here we show that ubiquitous degradation of DAF-2 in male C. elegans increases median lifespan by more than 440%, one of the longest lifespan extensions by a single intervention to date. Conversely, degrading DAF-2 in the male germline decreased lifespan, opposite of its effect in hermaphrodites3. Using male mating and reproductive success as a meaningful ecological and neurophysiological measure of healthspan, we found that ubiquitous degradation of DAF-2 greatly prolongs reproductive health, likely by prolonging function of the male intromittent organ in the tail. This work highlights the importance of studying sex differences in aging and highlights the utility of using C. elegans males to understand the underlying basis of enhanced lifespan and healthspan.

genetics↗

Pro-longevity compounds extend Caenorhabditis elegans male lifespan and reproductive healthspan

Sex differences in aging are robust and ubiquitous. Demographic differences in aging generated by sex have long been recognized, but the underlying biological basis for these differences and the potential for sex-specific interventions remain understudied. To explore sex differences in the response to pro-longevity interventions, we utilized the C. elegans aging model and asked whether male lifespan and reproductive healthspan can be extended via compounds known to have pro-longevity effects in hermaphrodites. We tested seven different compounds at two concentrations each and found that lifespan was extended under all tested conditions. However, reproductive healthspan measured by mating success in late life improved under only two tested conditions, sulforaphane and metformin. These results demonstrate that lifespan and healthspan can be decoupled in C. elegans males and offer a new framework for screening pro-longevity compounds and for studying sex differences in aging in a classical aging model.

physiology↗

Mating strategies in Caenorhabditis elegans populations are determined by male developmental history

Mating strategies, whether sexual or asexual, confer unique costs and benefits to populations and species that facilitate evolutionary processes. In wild isolates of Caenorhabditis elegans, mating strategies are dependent on developmental history. Outcrossing levels significantly increase when one or both parents have transiently passed through the stress-resistant dauer diapause stage. However, the molecular mechanisms of how life history alters mating strategies have not been systematically explored. Sex-specific responses to pheromones are a major driver of mating behaviors in C. elegans. We demonstrated previously that postdauer hermaphrodites exhibit a decreased avoidance of the pheromone ascr#3 due to the downregulation of the osm-9 TRPV channel gene in postdauer ADL neurons. Thus, we hypothesized that altered responses to pheromones in postdauer animals could contribute to increased outcrossing. We conducted mating assays using wild type N2 Bristol, as well as daf-3/co-SMAD and mut-16/Mutator strains that fail to downregulate osm-9 in postdauer hermaphrodite ADL neurons. First, we show that the outcrossing level of N2 Bristol correlated with the developmental history of males, and that postdauer males exhibited an increased ability to detect mates via pheromones compared to continuously developed males. In addition, DAF-3 plays a critical role in postdauer males to regulate mating, while playing a more minor role in hermaphrodites. Furthermore, the mut-16 strain exhibited negligible outcrossing, and attempts to rescue the outcrossing phenotype resulted in transgenerational sterility due to germline defects. Together, our results suggest a model whereby mating strategy is driven by developmental history under combinatorial control of TGF-{beta} and RNAi pathways.

genetics↗