Comparing the expression of genes involved in homologous recombination and non-homologous end-joining DNA repair pathways in soma and germline tissue in the bdelloid rotifer Adineta vaga

Abstract

Bdelloid rotifers are known to survive desiccation and high doses of ionizing radiation. This extreme resistance is notably due to their capacity to deal with numerous DNA double strand breaks (DSBs). Genes coding for proteins involved in non-homologous end-joining (NHEJ) DNA repair pathway have previously been observed to be highly expressed in the bdelloid rotifer Adineta vaga after exposure to ionizing radiation but not the genes coding for proteins involved in homologous recombination (HR). However, it is possible that the DNA repair pathways in somatic and germline nuclei of Adineta Vaga differ with the germline, being under-represented in transcriptomic or proteomic analyses of entire bdelloid rotifer individuals. In this study, we established an in situ hybridization on A. vaga individuals, to study a differential expression of RNA in somatic and germline tissue. We optimized first this technique by studying the expression of several candidate genes known to be highly expressed in bdelloid rotifer A. vaga: 60S ribosomal protein, HSP82, actin, and AvLigase E. The aim is to then investigate the spatial expression of DNA repair genes involved exclusively in NHEJ or in HR in A. vaga. We showed that Rad51 and Rad54, both being key players of HR are expressed in the developing oocyte of previously irradiated A. vaga. Rad51 was also expressed in the germo-vitellarium of irradiated rotifers and the developing oocyte of non irradiated rotifers while Rad54 was not. HSP82, 60S, PCNA and actin were found to be expressed around the nurse cell nuclei, corresponding to the germo-vitellarium whereas, AvLigase E was found to have a disperse expression in the entire body but not especially around the nurse nuclei. Ku80, specifically involved in NHEJ, showed a similar staining, indicating the possible general expression of this gene within the soma. Overall, our results bring new evidences for a differential expression between the soma (NHEJ) and germline (HR) DSB DNA repair in bdelloids A. vaga.

Date of Award	2022
Original language	English
Awarding Institution	University of Namur
Supervisor	Karine Van Doninck (Supervisor) & Victoria Moris (Co-Supervisor)