Gonad differentiation and puberty onset in the zebrafish: Evidence for the dependence of puberty onset on body growth but not age in females

Abstract

Puberty is the period in the vertebrate life cycle that marks the transition from sexual immaturity to maturity, enabling an animal to acquire adult reproductive functions. Puberty, an important point in vertebrate reproductive life, has been under extensive study in the past decades. It has been known for a long time that the initiation of puberty in mammals is closely associated with body growth and metabolism; however, there has been no equivalent report in small model teleosts such as the zebrafish. Using morphological and histological analysis, this study was undertaken to examine the timing of gonad differentiation and female maturation (puberty) in the zebrafish, with particular emphasis on the potential impact of body growth on the onset of puberty. Our data showed that gonad differentiation in the zebrafish completed around 35 days post-fertilization (dpf) in females and 45 dpf in males. Puberty in females is initiated at around 45 dpf. Our experiments provided clear evidence that the initiation of puberty in female zebrafish was strongly correlated with body size but not age, supporting the importance of the growth axis in the onset of puberty. This study provides essential information on basic characteristics of growth and reproduction in zebrafish.

Disruption of Zebrafish Follicle-Stimulating Hormone Receptor (fshr) But Not Luteinizing Hormone Receptor (lhcgr) Gene by TALEN Leads to Failed Follicle Activation in Females Followed by Sexual Reversal to Males

“…The control and mutant fish examined had similar body size (data not shown). As shown in Figure 2A, the control fish showed normal ovarian development with large PG follicles at 40 dpf and PV follicles at 45 dpf, a marker for puberty (55,56). In contrast, the ovaries of mutant fish were extremely small with only one or two layers of underdeveloped PG follicles in the section.…”

Developmental exposure to progestins causes male bias and precocious puberty in zebrafish (Danio rerio)

“…There is considerable plasticity in the age and size at which fish enter puberty. The timing of puberty is sensitive to environmental conditions like food availability, salinity, temperature and photoperiod (Chen and Ge, 2013;Melo et al, 2014). This is likely because reproductive success of fish, and especially of seasonally spawning fish, is dependent on that reproductive behavior is synchronized with the proper external environment (Rowe and Hutchings, 2003).…”

Zebrafish pituitary gene expression before and after sexual maturation

“…Puberty is defined as the period that marks the transition from sexual immaturity to maturity. It has been suggested that the onset of ovary maturation in female zebrafish occurs at around 45 dpf (Chen & Ge 2013). Under standard laboratory conditions, zebrafish normally exhibit a growth burst stage within 9-51 dpf, coinciding with the critical stage of their sex differentiation.…”

“…Zebrafish is phylogenetically closer to the farmed cyprinid fish species than any other vertebrate model, which makes it a useful organism to study the gene functions of aquaculture fish. All juvenile zebrafish develop an ovary-like structure (juvenile ovary), which will either develop into a definite ovary in females or transform into a testis in males around 45 days post-fertilization (dpf; Chen & Ge 2013). It takes w3 months to reach sexual maturity (Clelland & Peng 2009).…”