A study on the utilization of biotin in the embryos in domestic fowl
2007
Taniguchi, A.(University of Hyogo, Himeji (Japan)) | Watanabe, T.
It is known that biotin deficiency induces both external and skeletal malformations in the embryos of fowl. Also biotin is required for maintaining reproductive function and is contained in a large amount in the egg yolk. Therefore, this study was designed to elucidate the mechanism of transport of biotin from egg yolk to embryos. The data were obtained from the fertilized eggs of the white leghorn. In the egg yolk, biotin concentration was 600+-200 ng/g on day 1 and had decreased with the growth of the embryos. Biotinidase activity had also decreased after day 1. The percentage of free biotin was above 70% in egg yolks on days 2-11. Conversely in embryos, biotin concentration was the highest value, 206.4+-48.6ng/g, on day 3. Biotinidase activity showed the highest value on day 2. These results demonstrate that biotin is metabolized into free form soon after fertilization in the egg yolk and transported abundantly to embryos on days 3-4. In the embryo, the way of provision of biotin is different according to developmental stage or organ, and it may be that biotin is concerned with the formation of each organ or tissue. The expression of biotin-dependent carboxylase was shown only in acetyl-CoA carboxylase (ACC) and pyruvate carboxylase (PC) in the egg yolk, and ACC increased after day 2. In embryos, the expression of PC, propionyl-CoA carboxylase (PCC) and methylcrotonyl-CoA carboxylase (MCC) was shown, and PC increased with the growth of the embryos. Thus, the expression is different between egg yolk and embryos, and it appears that the way of using of biotin is different. Accordingly, this indicates that a large amount of biotin is provided from egg yolk to embryos. From these findings, biotin may be an essential nutrient and play an important role in the normal development of embryos in fowls.
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