Molecular regulation of reproduction in insect societies

1 PhD project offered in the IPP summer call 2019

Scientific Background

The main feature of social insects is the reproductive division of labor, whereby queens monopolize reproduction while sterile workers perform other tasks to maintain the colony. Investigating the molecular mechanisms regulating reproduction and division of labor in ants is necessary to understand the evolution and ecological success of insect societies. A common approach to study reproductive division of labor is to compare queen and worker castes. However, queens and workers not only differ in reproductive activity but also in morphology, lifespan, etc. In this context, the clonal raider ant Ooceraea biroi has emerged as a powerful study system to investigate gene regulatory processes and the molecular regulation of reproduction (Chandra et al. 2018, Libbrecht et al. 2016, Libbrecht et al. 2018). These ants produce female offspring by parthenogenesis, and colonies alternate between a queen-like phase when larvae are absent (all ants reproduce), and a worker-like phase when larvae are present (all ants stop reproducing to care for the brood). This allows the collection of genetically identical individuals only differing in their reproductive activity, thus facilitating the study of molecular mechanisms regulating reproduction.

PhD project proposal: Molecular regulation of reproduction in insect societies

The goal of this PhD project is to identify the gene regulatory mechanisms underlying gene expression changes modulating reproduction in O. biroi. To achieve this goal, we will identify putative gene regulatory mechanisms associated with reproduction, and investigate the functional link between social cues (presence of larvae), regulatory mechanisms, gene expression, and reproduction.

The genome, transcriptome and methylome of O. biroi are already available (Oxley et al. 2014, Libbrecht et al. 2016, Libbrecht et al. 2018), and O. biroi mutants have been recently generated using the Crispr/Cas9 system (Trible et al. 2017). Since we previously found that DNA methylation was unlikely to regulate reproduction in O. biroi (Libbrecht et al. 2016), we will use RNAseq and ChIPseq to focus on other mechanisms susceptible to regulate gene expression and reproduction (e.g., ncRNAs, histone modifications). We will also manipulate the presence of larvae, and use RNAi or Crispr/Cas9 to investigate the functional links between candidate regulatory mechanisms, gene expression and reproduction. This project will shed light on the regulation and evolution of reproductive division of labor in insect societies, as well as on how gene regulation can translate social cues into physiological changes.

Publications relevant to the project:

Chandra, V., Fetter-Pruneda, I., Oxley, P.R., Ritger, A.L., McKenzie, S.K., Libbrecht, R., and Kronauer, D.J.C. (2018). Social regulation of insulin signaling and the evolution of eusociality in ants. Science 361, 398–402.

Libbrecht, R., Oxley, P.R., Keller, L., and Kronauer, D.J.C. (2016). Robust DNA methylation in the clonal raider ant brain. Current Biology 26, 391–395.

Libbrecht, R., Oxley, P.R., and Kronauer, D.J. (2018). Clonal raider ant brain transcriptomics identifies candidate molecular mechanisms for reproductive division of labor. BMC Biology 16, 89.

Oxley, P.R., Ji, L., Fetter-Pruneda, I., McKenzie, S.K., Li, C., Hu, H., Zhang, G., and Kronauer, D.J. (2014). The genome of the clonal raider ant Cerapachys biroi. Current Biology 24, 451–458.

Trible, W., Olivos-Cisneros, L., McKenzie, S.K., Saragosti, J., Chang, N.C., Matthews, B.J., Oxley, P.R., and Kronauer, D.J.C. (2017). orco mutagenesis causes loss of antennal lobe glomeruli and impaired social behavior in ants. Cell 170, 727–735.

Contact:

Dr Romain Libbrecht

Department of Behavioural Ecology and Social Evolution
Johannes Gutenberg University Mainz

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