魁蚶母源大防御素在子代发育早期的动态变化

母源免疫因子能够通过卵细胞、母乳等方式转移给子代,在免疫系统发育成熟之前发挥重要的免疫保护作用,但贝类中的相关报道较少。为探索贝类非特异性免疫因子在子代发育早期的表达规律,本研究以魁蚶(Scapharca broughtonii)为研究对象,通过qRT-PCR和ELISA分析了大防御素在魁蚶胚胎及幼虫早期发育过程中mRNA和蛋白质的动态变化特征。结果显示,魁蚶卵子受精后发育至壳顶幼虫期,大防御素mRNA和蛋白质的表达变化趋势基本相同,即从受精卵期开始下降,至囊胚期最低,自担轮幼虫期表达量开始上升;与对照组相比,幼虫发育至担轮幼虫期,鳗弧菌(Vibrio anguillarum)处理组的大防御素升高更为显著,mRNA和蛋白的表达水平都基本高于对照组,说明鳗弧菌刺激能够上调担轮幼虫期后魁蚶幼体体内大防御素的表达量。总的来说,研究结果表明魁蚶母源性大防御素能够通过卵子传递给后代,从卵细胞受精后开始被消耗,当幼虫发育至担轮幼虫可能开始自身合成。

DYNAMIC EXPRESSION OF BIG-DEFENSIN IN DIFFERENT DEVELOPMENTAL STAGES OF EARLY-LARVEA OF SCAPHARCA OUGHTONII

It has been reported in various species that maternal immune factors, such as antibodies, lysozyme, and lectins, could be transferred to offspring from mother via egg and milk, and play important immune roles in developmental stage of embryos and larvae before immune system maturity. However, the expression characteristics of immune factors in different developmental stage of shellfish early-larvae remain lacking. In this study, quantitative real-time PCR (qRT-PCR) and enzyme linked immunosorbent assay (ELISA) were employed to investigate the dynamic expression of big-defensin during different developmental stages of early-larvae of ark shell Scapharca broughtonii. The results show that the mRNA and protein of big-defensin could be detected during stages from eggs to umbo-larvae, indicating clearly its maternal transfer properties. The mRNA and protein expression of big-defensin generally showed a similar variation trend, of which the expression level decreased from spermatovum stage to blastula stage, and then increased gradually from protrochophora stage. Compared to control group, the expression of big-defensin in Vibrio anguillarum change group increased after protrochophora stage, indicating that V. anguillarum could up-regulate the big-defensin expression. Therefore, the big-defensin in eggs could be consumed from fertilization to synthesization of protrochophora, and thus the immune system could generate at the protrochophora stage. This finding of big-defensin expression regularity may enhance our understanding of maternal transmission of immune factors in S. broughtonii, providing basic scientific data for the utilization of maternal immune.