Photoperiod-Specific Expression of Eyes Absent 3 Splice Variant in the Pars Tuberalis of the Japanese Quail.

The molecular mechanism underlying photoperiodic response in seasonal breeding animals such as the Japanese quail, red jungle fowl, sheep, mouse, and hamster involves thyroid-stimulating hormone beta subunit () mRNA expression in the pars tuberalis stimulated by the extension in day length. Furthermore, this mechanism is regulated by eyes absent 3 () in mammals. Even in birds, the expression of both and is induced in the pars tuberalis by the extension in day length; however, the relationship between the two genes is unknown. To clarify the function of EYA3 in quail photoperiodism, in the present study, we performed mRNA structure analysis of the Japanese quail mRNA using reverse transcription-polymerase chain reaction (RT-PCR) and Southern blot analysis. The results revealed that there are four types of splice variants within regions of exons 7, 8, and 9 of quail mRNA. Among the four splice variants of quail , the splice variant containing exon 7 was expressed in the pars tuberalis on the first long day, when quails were transferred from the short-day condition to the long-day condition. The results indicate that splice variant containing exon 7 is involved in the photoperiodic response of the pars tuberalis in the Japanese quail.