Yolk Proteins Of Macrobrachium Nipponense And Effects On Their Accumulation By Unilateral Eyestalk Ablation

Yolk proteins are the nutritious source in the developmental stage of crustaceans embryos and nauplii. Therefore, the synthesis, the accumulation and the quantity of them is very crucial to the embryos and nauplii. Vitellin is the major component of yolk proteins. In this dissertation, isolation, purification and biochemical characterization of the vitellin from the mature ovary of the freshwater shrimp, Macrobrachium nipponense was studied. This research established the theoretical basis on the synthesis mechanism of yolk proteins. The paper also focused on the effect to the accumulation of yolk proteins as the unilateral eyestalk is ablated. The study of it provided basic data in the further analysis of the effect of unilateral eyestalk ablation to the quality of eggs.1. The research on the vitellin of M. nipponenseWith the PAGE, still applying various staining methods, our study proved one form of vitellin in the mature ovary of M nipponense. According to this paper, the vitellin was purified by electric-elution. And an analysis was carried to its partial biochemical characterization.During the research, the molecular weight of the vitellin was 458Ku in a gradient native PAGE. Three subunits (110, 96, and 89 Ku) in purified vitellin were detected with SDS-PAGE. In the mean time, we found these three subunits all contained carbohydrate moieties based on the staining with periodic acid-Schiff s reagent. Three subunits of vitellin were also observed in SDS-PAGE whether the vitellin was reduced with j3-mercaptoethanol or not. So, we supposed that the disulfide bonds was no-existence among the three polypeptie subunits.By applying traditional immunity way and taking the purified vitellin as antigen to inject rabbit, the vitellin's specific antiserum was obtained. With this specific antiserum and applying immunology method, the vitellin of M nipponense were studied . The results showed: the vitellin of M nipponense was the female-specific protein ; both vitellin and vitellogenin had the same immunogenicity ; hepatopancreas might be the extraovarian site of vitellogenin synthesis. There was no immunological cross-reaction between the vitellin of M. nipponense and the vitellin or vitellogenin of other species , for example , M. rosenbergii , Fenneropenaeus chinensis , Litopenaeus vannamei , Eriocheir sinensis , and Brachydanio rerio.2. Effects on the accumulation of yolk proteins by unilateral eyestalk ablationUnilateral eyestalk ablation was performed with fine scissors, and the cut stump was cauterized. Our research proved that eyestalk ablation could accelerate ovary's growth speed, so as to pre-mature the shrimp. With the help of SDS-PAGE, we compared the elements of soluble proteins in the ovary between the shrimps of the experiment group (eyestalk ablation) and that of the control group(without ablation). Three weeks later, the proteins component in the experiment group had a little change. In contrast with the control group, the proteins component in the experiment group had a more protein which molecular weight was 93 Ku. We also compared the total proteins concentration between the experiment group and the control group by using Bradford, and compared vitellin in mature ovaries by rocket immunoelectrophoresis. In the mature ovaries, we found that both the proteins concentration and vitellin concentration in the experiment group were lower than that in the control group. It was obvious that, although eyestalk ablation could quicken the development of ovary, shorten the period of laying eggs, it could reduce the concentration of the total proteins and vitellin. As a result, it may effect on the quality of eggs and the survival rate of nauplii.