[시사매거진/광주전남] GST (Gwangju Institute of Science and Technology, President Ki-seon Kim) The research team of Professor Young-Joon Kim of the Department of Life Sciences investigated the mechanism by which the somatostatin neuropeptide released by the brain biological clock generates the circadian rhythm of egg formation.
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* Neuropeptide: Neuroprotein refers to proteins of relatively small size that neurons use to communicate with each other. Neuroproteins are known to be involved in a wide range of brain functions, including food intake, metabolism, reproduction, social behavior, learning, and memory and sleep. * Oogenesis: The process of generating mature eggs from the female ovary’s reproductive stem cells. The generation of yellow fruit fly eggs is divided into 14 stages. The glaze hormone, the main reproductive hormone in yellow fruit flies, allows the egg in stage 7 to mature into the egg in stage 8, which starts to accumulate egg yolk, inducing egg formation. |
The research team applied neuronal activity regulation technology and gene expression manipulation technology, and six pairs of circadian clock nerves (posterior dorsal nerves) out of about 100,000 neurons in the yellow Drosophila brain were found in the brainstem region of insulin growth hormone-secreting cells. It was discovered that it creates a circadian rhythm of egg formation by creating a secretion rhythm of Juvenile hormone (JH), a reproductive hormone that promotes egg formation through periodic inhibition of activity.
| * Posterior dorsal neuron 1 (DN1p): It is a part of 150 biological clock neural networks reported in the yellow Drosophila brain, and has high morning activity due to the influence of the M-nerve, which increases in activity in the morning. In previous studies, it was reported that this nerve induces circadian behavioral rhythm changes under the influence of temperature and light. In this study, it was found that the nerve is an essential biological clock in determining the rhythm of oocyte formation. |
Animals evolve to optimize the reproductive period for successful reproduction. Large mammals have a gestation period of more than 6 months, breed in the fall to give birth in spring, and small mammals and birds with a short gestation period mainly breed in the spring and give birth in summer. The biological clock of animals is estimated to play an important role in determining the breeding period by detecting changes in the length of day and night according to the season, but the mechanism for determining the breeding period of females is unknown.
The yellow fruit fly is an important model animal for circadian clock research, and researchers who isolated the circadian clock gene PERIOD from the yellow fruit fly won the 2017 Nobel Prize in Physiology or Medicine. The yellow fruit fly’s brain has about 150 nerves that perform the circadian clock function, creating a circadian rhythm of various physiological processes such as the hormone secretion rhythm along with the behavioral cycle of the yellow fruit fly. However, how the brain circadian clock generates the oocyte formation cycle, which is important for the formation of the reproductive period, remains unknown.
The research team was the first to discover that allatostatin-C, a somatostatin-based neuropeptide periodically released by DN1p biological clock nerves, inhibits the secretion activity of insulin growth hormone cells.
| * Somatostatin/ Allatostatin-C: As a kind of neuroprotein, it has high evolutionary preservation, such as found in vertebrates as well as invertebrates. It was first reported as a role in inhibiting the production and secretion of growth hormone in vertebrates, and is known to inhibit the secretion of the gonadotropin-releasing hormone that regulates the secretion of reproductive hormones. |
Allatostatin-C is a homolog to somatostatin, which is known to inhibit the secretion of gonadotropin-releasing hormone, which regulates the secretion of reproductive hormones in vertebrates including mammals. Somatostatin released by the biological clock in vertebrates. It is hypothesized that this reproductive hormone will generate a circadian cycle of secretion activity.
Prof. Young-Jun Kim said, “The causal relationship between the allatostatin-C release biotic clock nerve, secretion of reproductive hormones, and the rhythm of oocyte formation, which was first discovered in this study, is still unknown. We look forward to providing important insights.”
This research was conducted with the support of the Biomedical Science Convergence Research Institute project supported by GIST, the mid-sized researcher support project supported by the National Research Foundation of Korea, and the Korea Drosophila Resource Center. It was published online on January 26, 2021 in the world-renowned journal of the National Academy of Sciences (PNAS).
Reporter Kim Gong [email protected]
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