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为探讨高等动物糖尿病诱导剂对家蚕血糖含量的影响以及鉴定原核表达的家蚕素Ⅱ(BBXⅡ)的降血糖活性,通过给家蚕幼虫注射糖尿病诱导剂链脲佐菌素和BBXⅡ,调查家蚕的生理效应及血糖含量变化。分别以50~500μg/g的剂量给4龄24 h幼虫注射链脲佐菌素后12~48 h,会引起蚕体血液中的海藻糖含量升高,但与对照组的差异不显著;以250μg/g的剂量给5龄24 h幼虫注射链脲佐菌素后6 h,血液中的海藻糖含量显著升高,海藻糖酶活性显著降低。蚕体注射链脲佐菌素后表现出不同程度中毒症状,生长发育、存活率、茧质、眠性及后代的滞育性等均受到不同程度的影响。半定量RT-PCR检测表明,链脲佐菌素会导致家蚕体内BBX-Ⅱ基因的表达量下调,其中对4龄期幼虫的影响大于5龄期幼虫。用原核表达的BBXⅡ注射正常饲养的家蚕幼虫、饥饿后进食的幼虫和经链脲佐菌素处理的幼虫,均可引起血液中海藻糖含量显著降低和海藻糖酶活性升高,显示原核表达的BBXⅡ对家蚕具有降血糖活性。
In order to investigate the effect of higher animal diabetes-inducing agents on the blood glucose level of silkworm and to identify the hypoglycemic activity of prokaryotic expression of Bone Marrow II (BBXⅡ), the silkworm larvae were injected with streptozotocin And blood sugar levels change. The levels of trehalose in the silkworm blood were all increased at 12 ~ 48 h after injection of streptozotocin at 24 hrs of age at the dose of 50 ~ 500 μg / g, but the difference was not significant with the control group. At the concentration of 250 μg / g, the trehalose content in blood increased significantly and the trehalase activity decreased significantly at 6 h after injection of streptozotocin at 24 h. Silkworm injection of streptozotocin showed symptoms of varying degrees of toxicity, growth, survival, cocoon quality, dormancy and the offspring of diapause were affected to varying degrees. Semiquantitative RT-PCR results showed that streptozotocin induced a down-regulation of BBX-Ⅱgene expression in silkworms, of which the effect on 4th instar larvae was greater than that on 5th instar larvae. Injection of prokaryotic BBXII into the normally-fed silkworm larvae, post-starvation larvae, and streptozotocin-treated larvae both caused a significant decrease in the blood trehalose content and an increase in trehalase activity, indicating that prokaryotic expression BBX Ⅱ has hypoglycemic activity on silkworm.