RESUMO
In recent years, there has been a burgeoning interest in exploring the nuances of animal stress physiology, particularly in relation to parameters such as sex, and behavioral phenotype-dependent variations, that is crucial for understanding phenotypic variation and its role in evolutionary selection. However, a significant dearth remains in how chronic stressors affect organismal stress physiology concerning the aforesaid parameters. This void is even wider pertaining to the response of peripheral tissues, such as the skin, the organ with the highest surface contact area with the environment. Hence, we behaviorally grouped the zebrafishes based on their boldness and the body condition, whole-body cortisol response, along with examining the transcriptional response, global DNA methylome, and oxidative DNA damage in the skin upon chronic crowding. Upon baseline conditions, clear distinction between bold and shy phenotypes were found, particularly in males. The boldness index score distribution exhibited greater uniformity in males than in females. Regarding the body condition response to chronic crowding, shy males showed a significant relative decline compared to their bold counterparts, while this trend did not hold true for females. qPCR data revealed distinctive expression patterns in key genes which play critical roles in cellular processes such as stress mediated gene regulation, immune response, oxidative stress protection, and maintenance of genomic integrity through epigenetic modifications across behavioral phenotypes and sexes under both with and without chronic crowding stress. Global DNA methylation levels significantly declined only in chronically crowded shy males, and sex/behavioral phenotype-dependent trends in oxidative DNA damage were identified.
