拟穴青蟹糖代谢调控与利用的生理与分子机制

Combined techniques of aquatic animal nutrition, biochemistry, physiology and molecular biology, the proposed research aims at solving the problem of the pysiological and molecular mechanisms in metabolism regulation and utilization of carbohydrate for the mud crab, Scylla paramamosain, an important aquaculture species in southeast China. This research will systematically investigate the effects of dietary carbohydrate sources and carbohydrate contents on the plasma glucose level and the digestive enzyme activity, key enzyme's activities and gene expression of glycolysis and gluconeogenesis,the effects of the crustacean hyperglycemic hormone(CHH) on the plasma glucose level and the key enzyme's activities and gene expression of glycolysis and gluconeogenesis, comparison on utilization between monosaccharides and polysaccharides, interactions between dietary carbohydrate and protein and lipid, the effects of dietary carbohydrate sources and carbohydrate contents on gut microbiota in Scylla paramamosain. The results showed the trends of carbohydrate digestivie enzymes and glucose key metaoblic enzymes activities. Digestion and absorption database of different carbohydrate sources were established. The results revealed CHH on the role of regulation of glucose metabolism and plasma glucose tolerance,and the mechanism of regulation of key enzyme in glucose metabolism gene expression for Scylla paramamosain were evaluated. It is proposed to increase the measures of carbohydrate utilization ability. The results of the proposed research are expected to not only exposite physiological and molecular mechanisms in the carbohydrates metabolic regulation and utilization for mud crab, promoting research on the molecular nutrition of crustaceans, but also provide the theroetical basis of development efficient and environment- friendly commercial formulated feed for S. paramamosain.

以拟穴青蟹(Scylla paramamosain)为研究对象，综合水产动物营养学、生物化学、生理学和分子生物学等学科的方法，围绕拟穴青蟹糖代谢调控与利用的科学问题，研究糖源和含量对拟穴青蟹糖消化酶活性与糖代谢关键酶活性及其基因表达的影响，高血糖激素对拟穴青蟹血糖浓度及糖酵解和糖异生途径关键酶活性和基因表达的影响，拟穴青蟹对单糖和多糖利用能力的差异，拟穴青蟹饲料中糖、蛋白质和脂类的交互作用，糖源和含量对拟穴青蟹肠道菌群的影响。拟阐明拟穴青蟹糖消化酶和糖代谢关键酶活性变化趋势；获得拟穴青蟹对不同糖源的消化吸收数据库；揭示高血糖素对拟穴青蟹糖代谢调节作用以及拟穴青蟹葡萄糖的耐受性；探讨拟穴青蟹糖代谢关键酶基因表达的调控机理；探明糖对拟穴青蟹肠道菌群的关系等，为开发青蟹高效糖利技术奠定基础。研究成果不仅可阐明拟穴青蟹糖代谢调控与利用的生理和分子机制，而且可为开发高效环境友好型拟穴青蟹配合饲料提供

以拟穴青蟹(S. paramamosain)为对象，探讨了青蟹对6种糖源的表观消化率以及糖源和糖含量、铬对拟穴青蟹生长性能、糖代谢关键酶、肠道菌群、肝胰腺转录组基因表达谱等影响。结果表明，拟穴青蟹对糊化玉米淀粉、玉米淀粉、糊化小麦淀粉和木薯淀粉的表观消化率高。高筋面粉(GF)、玉米淀粉(CS)、木薯淀粉(TS)和小麦淀粉(WS)组的幼蟹的增重率、特定增长率显著高于麦芽糖(M)和葡萄糖(G)组的(P<0.05)，GF组、CS组、TS组和WS组的幼蟹成活率显著高于M组和G组(P<0.05)。糖源对幼蟹的淀粉酶和脂肪酶活性的影响显著(P<0.05)，对幼蟹蛋白酶活性影响不显著(P>0.05)。多糖提高了幼蟹抗氧化能力。青蟹肠道优势菌群为变形菌门(40%)，梭杆菌门(21%)，拟杆菌门(19%)，厚壁菌门(8%)，软壁菌门(6%)，螺旋体菌(6%)，糖源显著影响幼蟹肠道菌群。幼蟹糖代谢通路有521个基因/转录本，占总代谢通路的22%。对比葡萄糖组，麦芽糖组上调基因为205，CS组和GF组分别为248和226，WS组和TS组分别155和159，其中总有基因为35。对比G组，M组上调基因为216，CS组和GF组分别为273和295，WS组和TS组分别366和362，其中总有基因为105。G组和M组的HK、G6P、GCS酶的表达水平相近，CS组糖酵解水平高，WS组和GF组的这3个酶表达水平均较低。糖含量显著影响拟穴青蟹幼蟹的增重率、特定增长率、成活率等，随着饲料糖含量的升高，拟穴青蟹幼蟹的蛋白酶和脂肪酶活性影响不显著(P>0.05), 淀粉酶活性变化显著(P<0.05)。糖含量对肝胰腺HK、PFK、PK、G6 Pase等酶活性影响显著(P<0.05)，对FBPase及PEPCK活性影响不显著(P>0.05)。在试验条件下, 糖含量在20%~30%内,幼蟹均表现良好生长性能，糖含量的回归分析表明, 幼蟹饲料糖含量的适宜水平为25.8%。研究成果丰富了青蟹营养学知识，为开发青蟹高效配合饲料提供了基础资料，具有重要的理论意义和应用价值。