Vilella S, Zilli L, Ingrosso L, Schiavone R, Zonno V, Verri T, Storelli C
Laboratory of General and Comparative Physiology, Department of Biological and Environmental Sciences and Technologies, University of Lecce, Via Provinciale Lecce-Monteroni, 73100 Lecce, Italy.
J Comp Physiol B. 2003 Nov;173(8):679-86. doi: 10.1007/s00360-003-0379-z. Epub 2003 Aug 29.
D-Glucose absorptive processes at the gastrointestinal tract of decapod crustaceans are largely under-investigated. We have studied Na(+)-dependent D-glucose transport (Na(+)/D-glucose cotransport) in the hepatopancreas of the Kuruma prawn, Marsupenaeus japonicus, using both brush-border membrane vesicles and purified R and B hepatopancreatic cell suspensions. As assessed by brush-border membrane vesicle studies, Na(+)/D-glucose cotransport was inhibited by phloridzin and responsive to the (inside negative) membrane potential. Furthermore, it was strongly activated by protons (although only in the presence of an inside-negative membrane potential), which correlates with the fact that the lumen of crustacean hepatopancreatic tubules is acidic. When assayed in purified R and B cell suspensions, Na(+)/D-glucose cotransport activity was restricted to B cells only. Mab 13, a monoclonal antibody recognizing an 80- to 85-KDa protein at the brush-border membrane location, inhibited Na(+)/D-glucose cotransport in brush-border membrane vesicles as well as in enriched B cell suspensions. Primers designed after comparison of highly homologous regions of various mammalian sodium-glucose transporter) nucleotide sequences failed to produce RT-PCR amplification products from Kuruma prawn hepatopancreatic RNA. The molecular nature of this Na(+)/D-glucose cotransport system is still to be established.
十足目甲壳动物胃肠道中的D-葡萄糖吸收过程在很大程度上未得到充分研究。我们使用刷状缘膜囊泡和纯化的R型及B型肝胰腺细胞悬液，研究了日本对虾（Marsupenaeus japonicus）肝胰腺中依赖Na⁺的D-葡萄糖转运（Na⁺/D-葡萄糖共转运）。通过刷状缘膜囊泡研究评估，根皮苷可抑制Na⁺/D-葡萄糖共转运，且该转运对（膜内负电位）膜电位有反应。此外，它受到质子的强烈激活（尽管仅在膜内负电位存在时），这与甲壳动物肝胰腺小管腔呈酸性这一事实相关。当在纯化的R型和B型细胞悬液中进行测定时，Na⁺/D-葡萄糖共转运活性仅局限于B细胞。单克隆抗体Mab 13可识别刷状缘膜位置的一种80至85 kDa的蛋白质，它在刷状缘膜囊泡以及富集的B细胞悬液中均能抑制Na⁺/D-葡萄糖共转运。在比较各种哺乳动物钠-葡萄糖转运体核苷酸序列的高度同源区域后设计的引物，未能从日本对虾肝胰腺RNA中产生RT-PCR扩增产物。这种Na⁺/D-葡萄糖共转运系统的分子性质仍有待确定。
