Presentation Title

Rhox-10 mRNA Expression in Siberian Hamsters is Not Affected By Photoperiod-Mediated Changes in Testicular Function

Faculty Mentor

Kelly A. Young

Start Date

18-11-2017 2:15 PM

End Date

18-11-2017 3:15 PM

Location

BSC-Ursa Minor 95

Session

Poster 3

Type of Presentation

Poster

Subject Area

biological_agricultural_sciences

Abstract

Testis function in Siberian hamsters (Phodopus sungorus) is inhibited by short day lengths, whereas testicular activity is stimulated by long photoperiods. While the systemic neuroendocrine mediations of these changes are well understood, genes that regulate the seasonal loss and restoration of testicular function have not been identified. Because the cluster of Reproductive Homeobox X-linked (Rhox) genes encode transcription factors that are important in spermatogenesis, we hypothesized that these genes may be differentially regulated by photoperiod and thus affect testicular function. As a first step to address this hypothesis we sought to determine if 1) exposure to stimulatory photoperiod would restore photoinhibited testis function, and 2) if Rhox-10 was present in testes of Siberian hamsters and affected by changes in photoperiod. Male adult hamsters were exposed to long photoperiod (LD, control) or inhibitory short photoperiod for 14 weeks (SD), or short day for 14 weeks followed by transfer to LD for 1, 2, 4 or 8 weeks (post transfer, PT). SD exposure significantly reduced paired testis mass as compared to all other groups. Seminiferous tubule diameters and spermatogenic activity levels, assessed via histological analysis, significantly decreased with SD as compared to LD exposure, and returned to levels no different than LD after PT week 2. No differences in Rhox-10 mRNA expression were detected by real time PCR analysis, suggesting that photoperiod has no effect on Rhox-10 expression. These results indicate that testicular recovery after exposure to a stimulatory photoperiod is relatively rapid, but this transition may not be dependent on Rhox-10.

Key Words: testis, spermatogenesis, seasonal reproduction, photoperiod, Rhox

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Nov 18th, 2:15 PM Nov 18th, 3:15 PM

Rhox-10 mRNA Expression in Siberian Hamsters is Not Affected By Photoperiod-Mediated Changes in Testicular Function

BSC-Ursa Minor 95

Testis function in Siberian hamsters (Phodopus sungorus) is inhibited by short day lengths, whereas testicular activity is stimulated by long photoperiods. While the systemic neuroendocrine mediations of these changes are well understood, genes that regulate the seasonal loss and restoration of testicular function have not been identified. Because the cluster of Reproductive Homeobox X-linked (Rhox) genes encode transcription factors that are important in spermatogenesis, we hypothesized that these genes may be differentially regulated by photoperiod and thus affect testicular function. As a first step to address this hypothesis we sought to determine if 1) exposure to stimulatory photoperiod would restore photoinhibited testis function, and 2) if Rhox-10 was present in testes of Siberian hamsters and affected by changes in photoperiod. Male adult hamsters were exposed to long photoperiod (LD, control) or inhibitory short photoperiod for 14 weeks (SD), or short day for 14 weeks followed by transfer to LD for 1, 2, 4 or 8 weeks (post transfer, PT). SD exposure significantly reduced paired testis mass as compared to all other groups. Seminiferous tubule diameters and spermatogenic activity levels, assessed via histological analysis, significantly decreased with SD as compared to LD exposure, and returned to levels no different than LD after PT week 2. No differences in Rhox-10 mRNA expression were detected by real time PCR analysis, suggesting that photoperiod has no effect on Rhox-10 expression. These results indicate that testicular recovery after exposure to a stimulatory photoperiod is relatively rapid, but this transition may not be dependent on Rhox-10.

Key Words: testis, spermatogenesis, seasonal reproduction, photoperiod, Rhox