Project Type


Publication Date


Department or Program

Biological Sciences


College of Arts and Sciences

Faculty Mentor #1

Baker, Dianne


The goal of this research was to explore how photoperiod affects the reproductive endocrine axis in zebrafish (Danio rerio). It is known that the reproductive endocrine axis controls zebrafish reproduction. Additionally, it is known that photoperiod determines both reproductive seasonality (long days promote reproduction) and daily timing of spawning (initiates at the start of the light phase). However, there is limited research examining the effects of photoperiod on those endocrine pathways controlling zebrafish reproduction. I hypothesized that in males, long-day photoperiods promote the synthesis of key reproductive hormones, the gonadotropins (FSH and LH). To test this hypothesis, I used qPCR to compare gonadotropin transcript levels in male zebrafish that have been exposed to long photoperiods with those exposed to short photoperiods. I compared relative gonad sizes by calculating the gonadosomatic index (GSI). I found no significant differences in gonadosomatic index between groups. Additionally, I found no significant differences in mean LH transcript levels. However, there were significant differences in mean FSH transcript levels between the 14-day control group and 14-day short-day group, as well as the 14-day control group and 14-day long-day group. These results indicate photoperiod may affect FSH transcript levels. Future directions include conducting more trials using more fish and tanks to allow for a larger sample size, as well as using an ELISA to detect 11-KT concentrations.

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Biology Commons