Mother-to-embryo vitellogenin transport in a viviparous teleost Xenotoca eiseni

魚類がお腹の子供に与える栄養素を解明 --哺乳類が失った遺伝子を利用して胎生機構を獲得--. 京都大学プレスリリース. 2019-10-09.Vitellogenin (Vtg), a yolk nutrient protein that is synthesized in the livers of female animals, and subsequently carried into the ovary, contributes to vitellogenesis in oviparous animals. Thus, Vtg levels are elevated during oogenesis. In contrast, Vtg proteins have been genetically lost in viviparous mammals, thus the yolk protein is not involved in their oogenesis and embryonic development. In this study, we identified Vtg protein in the livers of females during the gestation of the viviparous teleost, Xenotoca eiseni. Although vitellogenesis is arrested during gestation, biochemical assays revealed that Vtg protein was present in ovarian tissues and lumen fluid. The Vtg protein was also detected in the trophotaeniae of the intraovarian embryo. Immunoelectron microscopy revealed that Vtg protein is absorbed into intracellular vesicles in the epithelial cells of the trophotaeniae. Furthermore, extraneous Vtg protein injected into the abdominal cavity of a pregnant female was subsequently detected in the trophotaeniae of the intraovarian embryo. Our data suggest that the yolk protein is one of the matrotrophic factors supplied from the mother to the intraovarian embryo during gestation in X. eiseni

Reduced muscle strength of knee extensors is a risk factor for silent lacunar infarcts among Japanese elderly people: the Bunkyo Health Study

Abstract Background Silent lacunar infarcts (SLIs) are often incidentally diagnosed by brain magnetic resonance imaging in elderly people and are associated with the future onset of stroke, dementia, and frailty. While decreased muscle strength was reported as a risk factor for stroke, it is still unclear whether it also predisposes to SLI. In this study, we investigated the association between muscle strength and SLI in elderly subjects. Methods The subjects were 1536 elderly people aged 65–84 years without previous stroke events, living in an urban area of Tokyo, Japan, and recruited in the Bunkyo Health Study. Lacunar infarcts were defined by brain magnetic resonance imaging. Muscle strength of the knee extensors was measured using a dynamometer. After categorizing subjects by age and sex, we divided them into three groups based on muscle strength tertiles (High, Medium, and Low) and investigated the association between muscle strength and SLI. Results The mean subject age was 73.0 ± 5.4 years, and 58.9% were female. The prevalence of SLI was 16.4% and was inversely associated with muscle strength (High, 12.3%; Medium, 17.7%; and Low, 19.3%; P for trend 0.003). After multivariate adjustment, the odds ratio for SLI was increased in the Medium and Low groups compared with the High group (High, 1.00 [reference]; Medium, 1.42 [95% confidence interval: 0.98–2.04]; and Low: 1.48 [1.02–2.14]), and the linear trend across the three groups was significant (P for trend 0.043). Conclusions Reduced knee extensor muscle strength is associated with SLI among Japanese elderly, independently of other established risk factors