Sexual determination and differentiation in teleost fish

Abstract

The present work reviews the latest information on the cellular, molecular and physiological aspects of sexual determination and differentiation in teleost fish. The group exhibits a large variety of mechanisms of sexual determination. These may be genetic, or depend on environmental conditions such as temperature, pH, and social factors, all of which can influence the proportion of the sexes. Additionally, sex steroids play an important role in the regulation of sexual differentiation. The patterns of gonadal sexual differentiation are diverse, and species may be hermaphroditic or gonochoristic, some of the latter displaying juvenile hermaphroditism. In recent years, several genes involved in the sexual determination and differentiation pathways in vertebrates, particularly in mammals, have also been characterized in teleosts. Conserved as well as diversified functions have been proposed.

Zebrafish sex: a complicated affair

“…Although SD has only been analyzed in a small subset of the 32 000 fish species (reviews: [3, 15]), there are plenty of examples for species with GSD (e.g. Japanese medaka [31], threespine stickleback [32] and Patagonian pejerrey [33]) and ESD (e.g.…”

Monocrotophos pesticide modulates the expression of sexual differentiation genes and causes phenotypic feminization in zebrafish (Danio rerio)

“…Cyp19, a member of the cytochrome P450 superfamily, plays a main role in gonadal sexual differentiation in teleosts. In fish, the outcome of this process (i.e., the development of a testis or an ovary) is regulated by the ratio between androgens and estrogens, which is controlled by aromatase (reviewed by Sandra and Norma, 2010). In addition, forkhead transcription factor gene L2 (foxl2) and doublesex/mab-3 related transcription factor 1 (dmrt1) are transcription factors that act upstream in the signaling cascades that regulate sexual differentiation in fish.…”

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“…On the other hand, in direct sex differentiation, undifferentiated gonads develop directly into ovaries or testes (Yamamoto, 1969). Nakamura et al (1998), Devlin and Nagahama (2002), Strüssmann and Nakamura (2002), Penman and Piferrer (2008) and Sandra and Norma (2010) have extensively reviewed the factors affecting sex differentiation, with genetic, endocrine, environmental and social factors all playing an important role.…”