On the blood group B gene-specified alpha-galactosyltransferase in the serum of the Japanese tortoise (Clemmys japonica).

Human blood group O cells were converted into B-active cells by incubation at either 4 degrees or 37 degrees with uridine diphosphate D-galactose and unfractionated serum from the Japanese tortoise (Clemmys japonica). The specificity of the converted cells was tested by their reactions with human anti-B, anti-A and rabbit anti-B sera. Under the conditions used, Bombay (Oh) type cells were not converted, and group-O foetal cells possessing a few H antigenic sites were only weakly converted into B-active cells. In addition, the agglutination titre of the converted cells with eel anti-H serum decreased. These results therefore indicate that the conversion depends upon the preference of H-substance on the red cells. The alpha-galactosyltransferase in tortoise serum thus resembles the transferase in human group-B serum and these results suggest that the mechanism of biosynthesis of blood group B substance in the tortoise is similar to that in humans.