Maternal age effects on offspring personality and stress neuroendocrinology in the mound-building mouse 05 September 2023 Host institution Laboratoire d’Ethologie Expérimentale et Comparée UR 4443 | LEEC Université Sorbonne Paris Nord - Campus Villetaneuse Website: http://leec.univ-paris13.fr/ Supervision of internship Heiko G. Rödel (Professeur) ; https://scholar.google.de/citations?user=CYj8VnoAAAAJ&hl=en Cédric Zimmer(Maitre de Conférences) ; https://scholar.google.de/citations?hl=en&user=S9M1iHkAAAAJ Project description Maternal effects occur when non-genetic characteristics of the mother affect the offspring phenotype. One of these characteristics can be mothers’ age. Maternal age effects on offspring traits such as on growth, health, survival or reproductive success are well established. However, maternal age effects on offspring behavioral phenotype have rarely been studied. The moundbuilding mouse (Mus spicilegus) is an interesting model to study such effects, as under natural conditions two distinct cohorts of primiparous mothers of old and young age emerge. On the one hand, as reproduction is typically paused during the winter, overwintering juvenile females start giving birth in spring at an age of around 8 months. On the other hand, females born and maturing during the same breeding season start reproducing at young age of around 3 months. Research questions and predictions: In this laboratory-based study, we will investigate the effects of maternal age on the emergence of offspring personality in the mound-building mouse. Maternal effects can be subject to natural selection, acting to adaptively shape offspring phenotype to the prevailing environment. Accordingly, the emergence of more proactive phenotypes in offspring born during the early breeding season, which will start reproducing within the same season at young age, may be selected for. Thus, we hypothesize that maternal age, which is strongly related to seasonality under natural conditions, may be an important contributor to offspring personality. In accordance with this assumption, we would predict that offspring from older mothers will be more proactive and exploratory. Indeed, preliminary findingsfrom our group point towards a higher exploration tendency in offspring from old compared to young mothers. Furthermore, we will study whether offspring from old and young mothers will also differ in personality-related parameters of stress neuroendocrinology. Methods: Personality types of juvenile mound building mice born to young mothers (around 3 months old) and to old mothers (around 8 months old) will be determined by repeated standardized behavioral tests at different ages (vocalization responses after maternal separation, behavior in open field and novel object settings). Furthermore, HPA axis activity will be assessed via corticosterone metabolite concentrations in feces by ELISA, and in terms of glucocorticoid receptor expression in the brain by qPCR. The candidate will carry out and learn the following procedures: behavioral experimentation, analysis of video recordings with specific software (BORIS, ICY Image Analysis), physiological (ELISA) and genetic (qPCR) analysis, statistical analysis of the data. Candidate: We are looking for a highly motivated student of animal behavior/behavioral ecology/ethology or from a related discipline, preferably with experience in animal experimentation. Applied knowledge of statistics, e.g., with the program R, will be advantageous. The working language will be English and French. The project will preferably start in January 2024. Interested candidates should contact us as soon as possible, not later than in September 2023. Contact: Prof. Heiko G. Rödel, LEEC; Email: heiko.rodel@univ-paris13.fr Laboratoire d’Ethologie Expérimentale et Comparée UR 4443, Université Sorbonne Paris Nord, F-93430 Villetaneuse