ビオチンと胎児発育(<特集>ビタミン・ミネラルと生殖【II】)

抄録

We have recently studied the mechanism for the supply of biotin from the maternal body to the ovary follicles or the egg yolk in domestic fowl. At first, it was clear that free biotin was being supplied in large amounts to growing ovarian follicles, particularly just before ovulation. We demonstrated that the biotin incorporated into follicles is transported in free form to embryos at the age of 3-4 days, and the transportation of biotin during embryogenesis differs according to the type of embryonic tissue. In mice, biotin is transported to the embryo from the dam over the course of the pregnancy. An especially large amount of biotin is supplied to the maxillofacial area between days 12 and 15 of gestation. These findings demonstrate a relationship between biotin and the formation and differentiation of tissues and organs. As for the expression of carboxylases, ACC (acetyl CoA carboxylase) was detected in both the yolks of domestic fowl and the livers of mouse dams. PC (pyruvate carboxylase), MCC (methylcrotonyl CoA carboxylase) and PCC (propionyl CoA carboxylase) were observed in their embryos, but ACC levels were low, so it was not detected using the Western blotting technique. In conclusion, the expression of carboxylases in yolks and embryos is organ-specific, perhaps because of the specific function of biotin. Our findings indicate that biotin is an essential nutrient and plays an important role in the embryonic growth of birds and mammals, and that it is important to maintain proper biotin levels during gestation.