Reduced Vitellogenesis and Female Fertility in Gper Knockout Zebrafish

Area of Science:

• Reproductive biology
• Endocrinology
• Molecular genetics

Background:

• The function of G-protein coupled estrogen receptor (GPER) in vertebrate reproduction is not fully understood.
• Estrogen receptors play vital roles in reproductive processes.

Purpose of the Study:

• To investigate the role of GPER in zebrafish ovarian follicle development and reproduction.
• To elucidate the molecular mechanisms underlying GPER's function in the reproductive system.

Main Methods:

• Generated a GPER knockout zebrafish line (gper) using TALEN technology.
• Assessed fertility, oocyte development, plasma vitellogenin levels, and gene expression in mutant and wild-type zebrafish.
• Quantified follicle stages and measured hormone levels.

Main Results:

• Gper mutant females exhibited significantly reduced fertility and embryo production (40.85% decrease).
• Ovaries of gper mutants contained more early vitellogenic follicles (Stage III) and fewer ovulated oocytes (Stage V), indicating retarded follicle development.
• Reduced plasma vitellogenin levels and lower epidermal growth factor receptor (Egfr) expression in Stage III oocytes were observed in gper mutants.

Conclusions:

• GPER plays a significant role in controlling ovarian follicle development in zebrafish.
• GPER regulates vitellogenesis and Egfr expression, which are critical for reproductive success.
• These findings clarify GPER's function in vertebrate reproduction.