Social Evolution: Epigenetic regulation of division of labor and ageing in social insects

1 PhD project offered in the IPP summer call 2021

Scientific background

Social insect queens exhibit extraordinarily long life spans with over 40 years. Their sterile workers are short-lived. Yet, whether an egg develops into a queen or a worker is not genetically determined in most social insects, but depends on environmental factors that influence divergent gene expression patterns. The epigenetic regulation of caste development and ageing is the focus of our research. We ask: How can ant queens live for several decades? How is ageing regulated on a molecular level? We could show that fecundity is positively associated with longevity (Negroni et al. in press) and that epigenetic marks such as histone acetylation play a role in the dynamic activity changes of genes important for a long life (Choppin et al. unpubl. ms). We also have demonstrated that in some cases parasites, such as a parasitic cestode, can cause an extension in life span (Beros et al. 2015). Indeed, infected workers live many times longer than uninfected workers (Stoldt et al. 2021). How parasites interfere with the regulation of life span in Temnothorax ants is therefore another focus of our research. Finally, we investigate the influence of the gut microbiome on ageing and immunity (Negroni et al. 2020). We could show that fertile workers live longer and responded to an immune challenge differently with changes in gene expression. Moreover, immune challenged workers downregulated the diversity of their microbial community in the gut. How, this is regulated (e.g. via microRNAs) and is linked to ageing will be the focus of future studies.

PhD project : Epigenetic regulation of ageing in ants

This project will investigate the molecular regulation of ageing in workers and queens using the small ant species Temnothorax rugatulus and Temnothorax nylanderi as our model organisms. We will analyze, how queens and workers change their gene expression with age and which regulatory mechanisms are involved. We focus on histone acetylation, DNA methylation and microRNAs as regulatory mechanisms, for which we have already evidence that they play a role in dynamically changing gene expression. We recently sequenced and annotated the genomes of both species (Jongepier et al. unpubl. ms) and already identified a number of candidate genes linked to lifespan in both species using RNAseq (Stoldt et al. 2021, Negroni et al. 2019, 2020, 2021). RNAi has been used successfully in Temnothorax ants to functionally annotate candidate genes (Kohlmeier et al. 2018) and we will use this method to investigate which genes linked to life span regulate known longevity pathways such as mTOR or IIS. Finally, we will investigate the role of parasites and diseases in ageing including how the parasitic cestode Anomotaenia brevis extends the lifespan of its ant host. Here we focus also on the role of the gut microbiome in immune defense and ageing. The diverse methods used will include experimental manipulations (e.g. using epigenetic inhibitors, inducing oxidative or immune stress), survival analyses, tissue-specific RNAseq, functional annotation via RNAi, Chip Seq to investigate histone acetylation, microRNA and lnc RNAs, ATAC seq, gut microbiome analyses 16S seq and the required bioinformatic analyses.

Publications relevant to this project

Negroni MA, Macit MN, Stoldt M, Feldmeyer B, Foitzik S (2021) Molecular regulation of lifespan extension in fertile ant workers.Philosophical Transactions of the Royal Society B, in press

Negroni MA, Feldmeyer B, Foitzik S (2021) Experimental increase in fecundity causes upregulation of fecundity and body maintenance genes in the fat body of ant queens. Biology Letters, 17:20200909

Stoldt M, Klein L, Beros S, Butter F, Jongepier E, Feldmeyer B, Foitzik S (2021) Parasite presence induces gene expression changes in an ant host and their function in immunity and longevity.Genes, 12:95

Negroni MA, Segers F, Vogelweith F, Foitzik S (2020) Immune challenge reduces gut microbial diversity and triggers fertility-dependent gene expression changes in a social insect.BMC Genomics, 21:816

Negroni MA, Foitzik S, Feldmeyer B (2019) Long-lived Temnothorax ant queens switch from investment in immunity to antioxidant production with age. Scientific reports, 9:7270

Contact

Prof. Susanne Foitzik

Email

Webpage