| This paper was mainly working on the biochemical changes (water, carbohydrate, lipid, fatty acid, protein, amino acid) during embryonic development of Cherax quadricarinatus. At the same time, we especially worked on the yolk protein-vitellin in two aspects: 1. Isolation, purification and characterization of vitellin from the ovary of female Cherax quadricarinatus. 2. Variation of protein and vitellin concentration during embryonic development.1 water , carbonateDuring the embryonic development, water content increased from 53.15 1.35% in fertilized egg stage to 81.75 1.79 % in prepare-hatching stage. The content of carbonate was high in the middle of embryonic stages. On the beginning of embryonic development, it increased 3.71 %(dry wet), but decreased from 7.41 % to 3.71 %(dry wet) in the end.2 lipid, fatty acidThis experiment was conducted to mensure and analyse the composition of lipid and fatty acid of the Cherax Quadricarinatus. The result indicated that the content of total lipid decreased during embryonic development. The predominant fatty acids of both neutral lipid and polar lipid were C18:l 9, C16:0, C18:3 3 and C18:0. Each fatty acids decreased with the development of embryo.3 metabolism of proteinThe compositions of the proteins and amino acids were mensurated and analyzed during the embryonic development of Cherax Quadricarinatus. The results indicated that the contents of the total protein and the total amino acids were all downtrend. The total protein contents reduced from 16.3%(wet weight) at the fertilized egg stage to 9.11% at the prepare-hatching stage. The total amino acid contents reduced from 58.05%(dry weight) at the fertilized egg stage to 47.49% at the prepare-hatching stage. The correlation between the total amino acid and the essential amino acid(except methionine) was prominent, the coefficients of variation were from 10.18% to 15.29%. In the non-essential amino acid , the contents of glutamine acid and aspartic acid were relatively high, but the content of cysteine was relatively low. It's indicated that the protein and amino acid were not only the construction substances of embryonicdevelopment, but also the dominating energy sources.The results indicated that concentration of vitellin decreased in the whole stage. It is a little decreased in stage II (3.19%) , then increased. After the highest in StageIV (4.67%), it decreased remarkably with embryonic development. The results suggested that vitellin was the major protein that was closely correlated with embryonic developmental stages.The experimental of the enzyme resulted that the activity of pepsin is low in the first three stages and stage VI, but it increased in stage IV, and reach the top of 22.25 1.89 U/mg prot. Meanwhile, the activity of trypsin is also in the first three stages ,but it reach the top of 16.69 1.23 U/mg prot. in stage V.4 characterization of vitellinA purified vitellin was isolated from the mature ovaries of the crayfish Cherax Quadricarinatus using chromatography and electrophoresis. The characterization of vitellin was carried out by SDS-PAGE. The result indicated that Vn has a molecular mass of 369kDa and have four bands (85.4, 80.6> 76.6, 73.7kDa). It has been suggested that the purified vitellin is a glyco-lipid-carotenoprotein. The amino acid composition of the vitellin has also been analyzed.The result of Western Blotting showed that the natural molecular weight of vitellin did not change, but the content decreased. On the basis of purification and immunity of vitellin, antibodies of vitellin were obtained and used to measure the concentration of vitellin in embryo in different stages of embryonic development by enzyme-linked immunosorbent assay (ELISA).
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