Comparison of transcriptomics and proteomics revealed distinct molecular mechanisms underlying egg development of...

Ecological adaptation, the process by which organisms acquire beneficial traits through natural selection, enhances survival but its molecular mechanisms are often poorly understood. A prime example is the fish species Culter alburnus, which has evolved a dichotomous reproductive strategy: Producing adhesive eggs in still waters and semi-buoyant eggs in flowing rivers. To elucidate the molecular basis of this adaptation, a comparative study of the two egg types was conducted. Our findings revealed that adhesive and semi-buoyant eggs employ distinct developmental strategies. Semi-buoyant eggs prioritize energy mobilization and protein synthesis to fuel rapid development. In contrast, adhesive eggs upregulate genes involved in immune regulation and cell adhesion. Further analysis revealed that semi-buoyant eggs enhance hydration through protein degradation and undergo extensive cytoskeletal remodeling via tubulin folding and collagen production. Adhesive eggs, however, utilize integrin-mediated interactions with proteins like TMEM132 and FN to regulate adhesion, a process coupled with egg envelope hardening. Our results demonstrate that the aquatic environment profoundly shapes physiological and transcriptional programs in fish eggs, offering significant insights into population-specific adaptations in teleosts.