Lengthening spring days trigger genes in the brain of the Japanese quail that, through a cascade of effects, prime the bird’s body for breeding, according to a research team reporting in Nature this week.
Led by Takashi Yoshimura of Nagoya University, Japan, the team made their discovery of how the quail’s brain tells its body that spring has arrived and it is time to breed by subjecting the birds to a sudden shift in day length, from short to long, and then studying gene activation in their brains.
When the quails are transferred to longer days, the genes are activated in two waves: roughly 14 hours after dawn on the first long day; and then some four hours later. These waves of gene activation have a range of effects including enlargement of the gonads, the researchers report.
The team’s analysis shows that the activation of a gene for a thyroid-stimulating hormone called tryotrophin is the crucial event that triggers the cascade. This occurs in a region of the brain called the pars tuberalis.
The work sheds light on the molecular mechanisms that regulate seasonal breeding in animals in response to changing day lengths. According to the researchers, the Japanese quail, Coturnix japonica, responds rapidly and dramatically to changes in day length so is a robust model for the study of these mechanisms.
Writing about the research in the News & Views section of Nature, Hitoshi Okamura of Kyoto University, says that researchers’ findings in Japanese quail are likely to hold for mammals.
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