Project description:In social insects, workers and queens arise from the same genome but display profound differences in behavior and longevity. In Harpegnathos saltator ants, adult workers can transition to a queen-like state called gamergate, which results in reprogramming of social behavior and life-span extension. Using single-cell RNA sequencing, we compared the distribution of neuronal and glial populations before and after the social transition. We found that the conversion of workers into gamergates resulted in the expansion of neuroprotective ensheathing glia. Brain injury assays revealed that activation of the damage response gene Mmp1 was weaker in old workers, where the relative frequency of ensheathing glia also declined. On the other hand, long-lived gamergates retained a larger fraction of ensheathing glia and the ability to mount a strong Mmp1 response to brain injury into old age. We also observed molecular and cellular changes suggestive of age-associated decline in ensheathing glia in Drosophila.
Project description:This experiment was performed to investigate the effect of the manipulation of social rank on gene expression. Fire ants newly mated queens were paired and placed in nesting chambers. After emergence of workers, queensM-^R behavior was monitored. Once the behavioral observation revealed the social rank of the two cofoundresses (winners and losers), queens were weighed again and re-paired with a different partner. We created the following three groups of queens: a) winner + winner (similar weight), b) loser + loser (similar weight), and c) winner + loser (different weights). Again, we monitored the behavior until the social rank of the newly coupled specimens was evident and we collected 4 new behavioral phenotypes in the same way as above: a) winners switched into losers (win/los), b) losers switched into winners (los/win), c) continuing winners (win/win) and d) continuing losers (los/los).
Project description:Using an organ-specific RNA-sequencing approach, we explore the role of supergene genotype and social environment on unmated, reproductive females Solenopsis invicta ants as they depart on their mating flights.
Project description:NG2 glia, also known as oligodendrocyte precursor cells (OPCs), play an important role in proliferation and give rise to myelinating oligodendrocytes during early brain development. In contrast to other glial cell types, the most intriguing aspect of NG2 glia is their ability to directly sense synaptic inputs from neurons. However, whether this synaptic interaction is bidirectional or unidirectional, or its physiological relevance has not yet been clarified. Here, we report that NG2 glia form synaptic complexes with hippocampal interneurons and that selective photostimulation of NG2 glia (expressing channelrhodopsin-2) functionally drives GABA release and enhances inhibitory synaptic transmission onto proximal interneurons in a microcircuit. The mechanism involves GAD67 biosynthesis and VAMP-2 containing vesicular exocytosis. Further, behavioral assays demonstrate that NG2 glia photoactivation triggers an anxiety-like behavior in vivo and induces anxiety-like behavior in a mouse model of chronic social defeat stress.
Project description:Senescence is manifested by an increase in oxidative stress and a decline in biological functions with age. In most organisms, body maintenance is traded-off with reproduction. The negative relationship between longevity and fecundity is also evident on the molecular level, yet the proximate mechanisms remain poorly understood. Apparently by-passing this trade-off, social insect queens are both extremely long-lived (up to 30 years in some ants) and highly fecund compared to workers. Here, we study changes in gene expression with age and fecundity in queens to determine how the trade-off between those two traits is reshaped. We analyse tissue-specific gene expression in young founding queens and old, highly fecund queens of the ant Temnothorax rugatulus. More genes altered their expression with age in the fat body than in the brain. Despite strong differences in ovary development, few fecundity genes were differentially expressed. However, many longevity genes involved in well-known pathways or lifespan-associated biological processes changed their expression with age indicating that multiple longevity mechanisms are activated successively throughout a queens’ life. Young queens invested in immunity (i.e. activation of the Toll signalling pathway) and resistance against environmental and physiological stress associated with the founding phase (i.e. down regulation of the TOR pathway), while established older queens up-regulate anti-aging mechanisms (i.e. up-regulation of catalase, superoxide dismutase, heat shock 70 kDa proteins). Finally, we identified a number of candidate genes and pathways, potentially involved in reshaping the fertility-longevity trade-off in social insects, shedding light on how this is achieved on a proximate level.
Project description:In most organisms, reproduction is correlated with shorter lifespan. However, the reproductive queen in eusocial insects exhibits much longer lifespan than workers. In Harpegnathos ants, when the queen dies, workers can undergo an adult caste switch to reproductive pseudo-queens (gamergates) exhibiting a 5X prolonged lifespan. To explore the relation between reproduction and longevity, we compared gene expression during caste switching. Insulin expression is increased in the gamergate brain that correlates with increased lipid synthesis and production of vitellogenin in the fat body, both transported to the egg. This results from activation of the mitogen-activated protein kinase (MAPK) branch of the insulin signaling pathway. In contrast, the production in the gamergate developing ovary of anti-insulin Imp-L2 leads to decreased signaling of the AKT/FOXO branch in the fat body, consistent with their extended longevity.
Project description:This SuperSeries is composed of the following subset Series: GSE22678: Transcriptome sequencing and analysis of two ants: Camponotus floridanus and Harpegnathos saltator GSE22679: Small RNA sequencing and analysis of two ants: Camponotus floridanus and Harpegnathos saltator Refer to individual Series
Project description:Animal longevity widely differs across species, and even individuals from the same species may exhibit different rates of ageing. In different species, the rate at which individuals actually age is related to the level of their social interactions, but this was still not known in ants. In a given colony, ant individuals are close genetic relatives, exhibit very different behaviours and a contrasted lifespan according to the Caste. Such characteristics constitute main advantages to study relationships between sociality and ageing. Therefore, the aim of this study was to characterize differences in the proteome of Lasius niger queens versus that of domestic and foraging workers. Proteomic data were put in relation with the behaviour of individuals from the three Castes. Hence, it was found that sociality correlates with ant longevity, with i) social immunity enabling the queen to mainly invest in soma protection, and ii) marked exposition of workers to the environment and nutrients inducing metabolic pathways that reduce their lifespan.