Morphological and Endocrine Aspects of Sex Differentiation in the European Sea Bass and Implications for Sex Control in Aquaculture

Retinoic acid signaling pathway : gene regulation during the onset of puberty in the European sea bass.

“…This means that the final sex ratios in a population depend on both genetic inheritance and the thermal regime during a thermosensitive period located during larval development and early ontogenesis . Male-skewed sex ratios in farmed populations can be obtained by increasing the temperature of the rearing water , or by adding androgens to the diet during early development (Blázquez et al, 2001;Blázquez et al, 1995;Blázquez and Saillant, 2019;. Manipulation of sex determination by the induction of polyploidy, gynogenesis and androgenesis show that these technologies could be advantageous in the production of large sized fish and useful for the creation of genomic tools for this species, such as linkage maps and genome sequencing (reviewed in Felip and Piferrer, 2019).…”

“…The European sea bass is a differentiated gonochoristic species. Moreover, sex differentiation is more dependent on length than on age (Blázquez and Saillant, 2019; and sex-related size differences are established before histological differentiation of the gonads (Koumoundouros et al, 2002;Papadaki et al, 2005;Saillant et al, 2002;Blázquez and Saillant, 2019). In addition, sex differentiation is influenced by environmental conditions (Vandeputte et al, 2007) and the temperature of the rearing water is confirmed as the main environmental cue responsible for the high male proportions found under intensive farming conditions (Blazquez et al, 1998;Koumoundouros et al, 2002;Mylonas et al, 2005;Pavlidis et al, 2000;Saillant et al, 2003;Sfakianakis et al, 2013).…”

“…PGCs in the European sea bass can be identified by electron microscopy and through the expression of the vasa gene, a molecular marker implicated in the transduction of mRNAs involved in the differentiation of gonadal-specific cell types Nishimura and Tanaka, 2014). Under culture conditions, gonads remain histologically undifferentiated during most of the first year of life (Roblin andBruslé, 1983, Blázquez andSaillant, 2019). PGCs can be histologically identified as early as 25 days post fertilization (dpf), start migrating and colonizing the gonadal ridges at 35 dpf, and rapidly proliferate between 50 and 100 dpf (Roblin and Bruslé, 1983;.…”