Fish reproductive endocrinology a journey from basic to applied

Abstract

In the early seventies marine fish culture became a reality and the study of fish reproductive process was an unavoidable need. So, I became interested in fish reproductive endocrinology, a breadth field with a spanning spectrum from very fundamental research to its zootechnical translation. Then, two reviews on fish pituitary gland (Pickfrod and Atz, 1957) and fish reproduction (Fish Physiology, VIII: Hoar and Randall, 1969) had tremendous impact on the field, as they compiled all the existing information providing insights on the understanding of gametogenesis, the hormones that control it, their mechanisms of action and their environmental interactions helping, as well, to address challenges frequently raised by the aquaculture industry. Here I intent to provide a journey along 35 years of research that gave rise to a wealth of basic information on fish reproductive endocrinology, and its transfer to the fish culture industry as practical uses and new technologies. I will focus on the European sea bass; a marine teleost where intensive basic reproductive endocrinology research has been driven by applied challenges. Since earlier studies on gonad morphology, seasonal changes of reproductive hormone levels and hormonal and environmental shifting of gametogenesis and spawning, novel discoveries were made on the Kiss/GPR54 and GnRH/GnRHR systems multiplicity and their functional significance, the structure/function of gonadotropis, gametogenesis and steroideogenesis, crosscommunications between the components of the brain-pituitary-gonadal (BPG) axis, its environmental control, sex differentiation and puberty. As we entered in the genomics era the associated technologies such as gene-transfer and recombinant hormone production, among others have been used to identify and study genes involved in reproduction and their regulation by environmental and endocrine factors. The output of this research enables the industry to produce good quality gametes, fertilized eggs and viable juveniles on demand.