How To Make Zebrafish Switch Sex

Scientists have found that the number of primordial germ cells regulates the gonadal switch in zebrafish.

AsianScientist (Dec. 12, 2014) – Tweaking the number of gonadal stem cells can control whether zebrafish turn out male or female, according to research published in Stem Cell Reports. These findings could find applications in aquaculture, where the sex ratio of cultured stocks controls aspects such as size, color and maturation in several fish species.

Zebrafish (Danio rerio) are small-bodied ornamental fish that have become an important model for vertebrate biology over the past four decades. Every zebrafish individual starts to develop as an immature female and future males must undergo a ‘gonadal transformation’ to produce functional testes. However, the molecular regulation of this process appears to be complex and is poorly understood.

Researchers from the Temasek Life Sciences Laboratory—in collaboration with Japanese scientists from Hokkaido University and Ehime University—have now found that the number of specialized gonadal stem cells known as primordial germ cells (PGCs) plays a regulatory role during sexual differentiation in zebrafish.

Using both morpholino depletion and transplantation into PGC-lacking fish, they demonstrated that a reduction in the number of PGCs results in more males presumably by forcing some of the females to change their sex permanently without affecting their fertility.

“These data show that a PGC counting mechanism in the gonad determines sexual development, giving rise to the hypothesis of PGC dosage-dependent sex differentiation. This provides a novel perspective to research on sexual development of fishes and a new insight in vertebrate germline biology,” said study co-author associate professor Rie Goto at Ehime University.

“Better understanding of this ‘gonadal switch’ in zebrafish might eventually lead to improved tools for sex control in cultured fish species, especially in ‘sex changing’ food fishes, such as the groupers or Asian seabass, and improvements in their farm-based culture,” commented Professor László Orbán, senior principal investigator at Temasek Life Sciences Laboratory and corresponding author of the present study.

The article can be found at: Tzung et al. (2014) Early Depletion of Primordial Germ Cells in Zebrafish Promotes Testis Formation.


Source: Temasek Life Sciences Laboratory; Photo: Tohru Murakami/Flickr/CC.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

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