Verri T, Mandal A, Zilli L, Bossa D, Mandal P K, Ingrosso L, Zonno V, Vilella S, Ahearn G A, Storelli C
Laboratory of General Physiology, Department of Biology, University of Lecce, Italy.
Comp Biochem Physiol A Mol Integr Physiol. 2001 Oct;130(3):585-606. doi: 10.1016/s1095-6433(01)00434-2.
Physiological mechanisms of gastrointestinal absorption of organic solutes among crustaceans remain severely underinvestigated, in spite of the considerable relevance of characterizing the routes of nutrient absorption for both nutritional purposes and formulation of balanced diets in aquaculture. Several lines of evidence attribute a primary absorptive role to the digestive gland (hepatopancreas) and a secondary role to the midgut (intestine). Among absorbed organic solutes, the importance of D-glucose in crustacean metabolism is paramount. Its plasma levels are finely tuned by hormones (crustacean hyperglycemic hormone, insulin-like peptides and insulin-like growth factors) and the function of certain organs (i.e. brain and muscle) largely depends on a balanced D-glucose supply. In the last few decades, D-glucose absorptive processes of the gastrointestinal tract of crustaceans have been described and transport mechanisms investigated, but not fully disclosed. We briefly review our present knowledge of D-glucose transport processes in the crustacean hepatopancreas. A discussion of previous results from experiments with hepatopancreatic epithelial brush-border membrane vesicles is presented. In addition, recent advances in our understandings of hepatopancreatic D-glucose transport are shown, as obtained (1) after isolation of purified R-, F-, B- and E-cell suspensions from the whole organ by centrifugal elutriation, and (2) by protein expression in hepatopancreatic mRNA-injected Xenopus laevis oocytes. In a perspective, the applicability of these novel methods to the study of hepatopancreatic absorptive function will certainly improve our knowledge of this structurally complex organ.
尽管确定营养吸收途径对于水产养殖的营养目的和均衡饲料配方都具有相当重要的意义，但甲壳类动物胃肠道对有机溶质的生理吸收机制仍严重缺乏研究。有几条证据表明，消化腺（肝胰腺）起主要吸收作用，中肠（肠道）起次要吸收作用。在吸收的有机溶质中，D - 葡萄糖在甲壳类动物新陈代谢中的重要性至关重要。其血浆水平由激素（甲壳类高血糖激素、胰岛素样肽和胰岛素样生长因子）精细调节，某些器官（即脑和肌肉）的功能很大程度上取决于平衡的D - 葡萄糖供应。在过去几十年中，已经描述了甲壳类动物胃肠道的D - 葡萄糖吸收过程并研究了转运机制，但尚未完全揭示。我们简要回顾一下目前关于甲壳类动物肝胰腺中D - 葡萄糖转运过程的知识。本文讨论了以前用肝胰腺上皮刷状缘膜囊泡进行实验的结果。此外，还展示了我们在肝胰腺D - 葡萄糖转运方面的最新认识进展，这些进展是通过以下方式获得的：（1）通过离心淘析从整个器官中分离出纯化的R - 、F - 、B - 和E - 细胞悬液后；（2）通过在注射肝胰腺mRNA的非洲爪蟾卵母细胞中进行蛋白质表达获得。从长远来看，这些新方法在肝胰腺吸收功能研究中的应用肯定会增进我们对这个结构复杂器官的了解。
