Aquaculture for all

Scientists Discover New Mechanism for Sex Control in Zebrafish

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New research has discovered that the reduction of gonadal stem cells will yield more male zebrafish. The findings, by Lszl Orbn et al, Temasek Life SciencesLaboratory, suggest that a stem cell counting mechanism in the zebrafish gonad is important for determining sexual development, which provides new insight in vertebrate germline biology.

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There are more fish species on Earth than all other vertebrates combined. Fishes are very diverse not only in their external appearance, but also in the way their sexual development is controlled.

Zebrafish 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.

The molecular regulation of this process appears to be complex and poorly understood.

However, researchers from Temasek Life Sciences Laboratory (Singapore) - in collaboration with Japanese scientists from Hokkaido University and Ehime University - reveal that the number of PGCs plays a regulatory role during sexual differentiation in zebrafish.

Using different methods and zebrafish lines, they demonstrate 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 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.

Further Reading

You can view the full report and list of authors in Stem Cell Reports by clicking here.

December 2014