| Research Abstract |
In order to determine the cause of inbreeding depression in the early developmental stage in Japanese quail, free amino acids of yolk, enzyme activities, contents of protein and nucleic acids, and incorporations of amino acids and nucleoside(thymidine, uridine)into embryos were analyzed biochemically in this study. Prior to biochemical examination, embryonic mortality was examined. The marked high embryonic mortality in the early developmental stage was found in the full-sib mating group and increased remarked with inbreeding. Furthermore, the decrease in the cell division and proliferation of the early embryos was found in the full-sib mating group by morphological examination. The free amino acids of yolk in the full-sib mating group were lower in contents than random mating group, showing the large differences at the 3rd generation.
Hexokinase, phosphorylase and glucose 6-phosphate dehydrogenase activities were significantly lower in the full-sib mating group and decreased with inbreeding. The relationships between these enzyme activities and embryonic development were found in the two mating groups. The marked reduced contents of protein, DNA and RNA were observed in the full-sib mating group when compared with random mating group. Lower values of protein/DNA and RNA/DNA in 2 days embryos were also found in the full-sib mating group. Incorporations of ^<14>C-glycine, leucine, glutamic acid, and ^3H-thymidine and uridine into embryos were depressed in the full-sib mating group. RNA analysis of the early embryos did not succeed because of technical problem and will be advanced further.
These results indicate that the increase of embryonic mortality and retardation in the full-sib mating group might be caused by the lack of free amino acids and the decrease in the metabolic function related to enzyme, protein and nucleis acid synthesis.
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