Transcriptomic signatures of social experience during early development in a highly social cichlid fish

Abstract

The social environment encountered early during development can temporarily or permanently influence life history decisions and behaviour of individuals and correspondingly shape molecular pathways. In the highly social cichlid fish Neolamprologus pulcher, deprivation of brood care permanently affects social behaviour and alters the expression of stress axis genes in juveniles and adults. It is unclear when gene expression patterns change during early life depending on social experience, and which genes are involved. We compared brain gene expression of N. pulcher at two time points during the social experience phase when juveniles were reared either with or without brood care, and one time point shortly afterwards. We compared (a) whole transcriptomes and (b) expression of 79 genes related to stress regulation, in order to define a neurogenomic state of stress for each fish. At developmental day 75, that is, after the social experience phase, 43 genes were down‐regulated in fish having experienced social deprivation, while two genes involved in learning and memory and in post‐translational modifications of proteins (PTM), respectively, were up‐regulated. Down‐regulated genes were mainly associated with immunity, PTM and brain function. In contrast, during the experience phase no genes were differentially expressed when assessing the whole transcriptome. When focusing on the neurogenomic state associated with the stress response, we found that individuals from the two social treatments differed in how their brain gene expression profiles changed over developmental stages. Our results indicate that the early social environment influences the transcriptional activation in fish brains, both during and after an early social experience, possibly affecting plasticity, immune system function and stress axis regulation.

Genome-Wide Epigenomic Stress Response in the European Sea Bass (Dicentrarchus Labrax, L.)

“…This is however not the rst RRBS protocol dedicated to the addition of a second restriction enzyme [104], but this is hereby proposed in a context of improved multiplexing of samples and increased sequencing capacities, thus offering more opportunities to explore important biological processes, such as the stress response. Data allowed us to explore how RBC's DNA methylation may respond to stressors in the European sea bass and -albeit some limitations discussed below -was shown to complement both the traditional evaluation of the stress response based on analyses of blood serum samples [85,105], or on gene expression variation, often using invasive brain samples [93,94,[106][107][108][109][110][111].…”

Genome-wide epigenomic stress response in the European sea bass (Dicentrarchus labrax, L.)

“…This is however not the first RRBS protocol dedicated to the addition of a second restriction enzyme [104], but this is hereby proposed in a context of improved multiplexing of samples and increased sequencing capacities, thus offering more opportunities to explore important biological processes, such as the stress response. Data allowed us to explore how RBC’s DNA methylation may respond to stressors in the European sea bass and - albeit some limitations discussed below - was shown to complement both the traditional evaluation of the stress response based on analyses of blood serum samples [85,105], or on gene expression variation, often using invasive brain samples [93,94,106–111].…”

“…Aluru and Vijayan 2009; Rey et al 2013; Martos-Sitcha et al 2014; Ghalambor et al 2015. Wong et al 2015; Metzger and Schulte 2016; Gerlai et al 2017; Nyman et al 2020).…”

“…Candidate genes coming from other fish studies with role in memory consolidation could be added (see, e.g. Nyman et al 2020; Yang et al 2020 for proposals).…”

Genome-wide epigenomic stress response in the European sea bass (Dicentrarchus labrax, L.)

“…We showed that RBC's DNA methylation may respond to stressors in the European sea bass, but remains relatively stable over time and is mostly in uenced by genetic background. In spite of confounding factors, results suggest that some epigenetic marks could complement both the traditional evaluation of the stress response based on analyses of blood serum samples [85,105], or on gene expression variation, often evaluated using invasive brain samples [87,93,94,[106][107][108][109][110][111].…”