CELLULAR-LOCALIZATION AND PROPOSED FUNCTION OF MIDGUT TREHALASE IN THE SILKWORM LARVA, BOMBYX-MORI
CELLULAR-LOCALIZATION AND PROPOSED FUNCTION OF MIDGUT TREHALASE IN THE SILKWORM LARVA, BOMBYX-MORI
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DOI：
10.1016/0040-8166(85)90030-8
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发表时间：
1985-01-01
期刊：
影响因子：
2.6
通讯作者：
YAMASHITA, O
中科院分区：
文献类型：
--
作者：
AZUMA, M;YAMASHITA, O
山梨糖醇密度梯度分析与几个标志酶的援助表明，中肠海藻糖酶的家蚕幼虫，家蚕，是本地化的微粒体膜，而不是在线粒体，溶酶体和微绒毛的顶端表面。电子显微镜检查表明，海藻糖酶富集的膜组分由来自内质网和质膜部分而不是微绒毛膜的膜泡的异质混合物组成。海藻糖酶活性的酶组织化学染色的中肠部分可以检测到只有在基底表面的上皮细胞对血腔。这种特异性定位进一步证实了免疫组织化学与过氧化物酶结合的抗体技术。因此，家蚕幼虫中肠海藻糖酶位于上皮细胞基底面的质膜上。在含有[14C]海藻糖的培养基中体外孵育的完整中肠制剂可以将海藻糖水解为葡萄糖并将其吸收到细胞中，尽管当孵育时间延长时，一些葡萄糖被释放到培养基中。这些结果表明，中肠海藻糖在血淋巴海藻糖的利用中起生理作用，而不是在营养吸收中。
A sorbitol density gradient analysis with the aid of several marker enzymes demonstrated that midgut trehalase of the silkworm larvae, Bombyx mori, was localized in the microsomal membranes, but not in mitochondria, lysosomes and microvilli at the apical surface. Electron microscopic examination showed that trehalase-enriched membrane fraction consisted of heterogeneous mixtures of membrane vesicles derived from the endoplasmic reticulum and plasma membrane parts other than the microvillus membrane. The enzyme-histochemical stains of trehalase activity on the midgut section could be detected only at the basal surface of the epithelium against haemocoel. Such a specific localization was further confirmed by immunohistochemistry with the peroxidase-conjugated antibody technique. Thus, it is concluded that midgut trehalase of silkworm larvae is situated on the plasma membrane at the basal surface of the epithelium. An intact preparation of midgut incubated in vitro in the medium containing [14C]trehalose could hydrolyse trehalose into glucose and take it up into the cell, although some glucose was liberated into the medium when incubated for extended periods. These results suggest that midgut trehalose plays a physiological role in utilization of haemolymph trehalose not in nutrient absorption.