【作者】 文祝友；

【导师】 肖调义；

【作者基本信息】 湖南农业大学 ， 渔业， 2008， 硕士

【摘要】 三角帆蚌(Hyriopsis cumingii)是中国特有的优质淡水育珠蚌。目前,其养殖规模不断扩大,养殖水域超负荷运行,使得三角帆蚌种质资源严重退化。虽然我国关于三角帆蚌育珠的研究已有悠久的历史,但仍有许多与养殖相关的基础理论尚未弄清,尤其是关于三角帆蚌消化生理方面的相关问题。本文对三角帆蚌(Hyriopsis cumingii)消化系统的形态结构、消化酶的最适pH值,以及在不同藻类培养条件下消化酶活性变化等方面展开了研究,旨在为贝类消化生理以及人工培养淡水藻类提供理论依据。采用大体解剖及光镜技术对三角帆蚌消化系统进行了形态解剖研究。观察结果:三角帆蚌的消化系统由消化腺-肝脏和消化道构成,消化道包括口、食道、胃、前肠、中肠、后肠、直肠、肛门几部分组成。口位于前闭壳肌下,口两侧各有一对三角形唇片,食道紧接口的后面,极短;胃与食道相连,体积较小;胃周围有一对肝脏;晶杆(胶质棒状结构)与胃内的胃盾相接触,肠由内外两管构成,根据内肠管结构变化分为:前肠、中肠、后肠、直肠四部分。前肠与胃相连,晶杆和前肠内管出胃时同包在一条囊管中,盘曲于内脏团内:中肠(由前肠内管突然变小部位至后面肠内管膨大部位,中间只有外囊管相连),外囊管内充满食物,盘曲于内脏团后部内;后肠(由膨大部位至穿过心脏),外囊管内充满食物;直肠(由心脏至肛门),肠外包管管道内充满食物和排泄物;肛门开口于后闭壳肌上,位于出水管附近。三角帆蚌消化系统组织结构:肝脏又称消化盲囊,是蚌体最主要的消化器官。组织切片显示它由众多分支的小盲管组成.按结构和功能可区分为肝总管和肝小管两部分。消化道管壁由粘膜层、粘膜下层和浆膜组成,没有肌层。但肠外包管具有肌肉层,由前到后肌肉层逐渐增厚。粘膜层由具纤毛的长形柱状细胞组成.在消化道的不同部位,粘膜层和粘膜下层的结构略有差异,后肠粘膜上皮也呈不规则凹凸,胃粘膜上皮比肠粘膜上皮稍厚,除此之外肠上皮还具分泌粘液的杯状细胞,尤以后肠粘膜上皮杯状细胞数量最多。本实验采用Folin-酚法、碘-淀粉比色法和DNS法等分别测定了三角帆蚌消化系统的肝脏、胃、前肠、中肠、后肠和直肠的蛋白酶、淀粉酶、纤维素酶的活性,以及各酶活性的最适pH值。结果表明,蛋白酶活性由高到低为:胃＞肝脏＞前肠＞中肠＞后肠＞直肠,除直肠(pH=7.5)外,其它器官蛋白酶活性最适pH值均为7.0;淀粉酶活性由高到低为:胃＞后肠＞肝脏＞中肠＞前肠＞直肠,肝脏、胃和后肠的淀粉酶活性最适pH值为7.5,而前肠、中肠和直肠的为7.0;纤维素酶活性由高到低为:胃＞中肠＞肝脏＞后肠＞前肠＞直肠,肝脏的纤维素酶活性最适pH值为5.0,其它器官的均为4.6。在不同藻类培养条件下,两组蛋白酶、淀粉酶、纤维素酶活性都存在显著和极显著的差异。更多还原

【Abstract】 Triangle sail mussel (Hyriopsis cumingii) is the most important freshwater pearl mussels in China. Both the enlarging farming scale and overloaded aquacultural water resource lead to a serious regression of germplasm resources of Hyriopsis cumingii. Although it has been for a long time that Hyriopsis cumingii was used to commercially exploited for freshwater pearl culture in China, a number of basic theories associated with aquaculture have not yet been clarified, particularly in digestive physiology of Hyriopsis cumingii. In this study, the morphological structure of digestive system, the optimal pH value of digestive enzymes activity, and the variation of digestive enzymes under different algal culture conditions were investigated, which will provide basic imformation on shellfish digestive physiology and alga’l cultivation.The morphological anatomy of the digestive system was studied by using anatomy and optical microscope techniques. The results showed that the digestive system of Hyriopsis cumingii was constituted of digestive gland and enteron. The former only contained the liver, while the latter included the mouth, esophagus, stomach, foregut, midgut, hindgut, rectum, anus, and so on. The mouth, which had a pair of triangular piece lip on two sides, was under anterior adductor muscle. Esophagus was very short at the back of the mouth. The volume of stomach was small. A pair of liver surrounded the stomach. Contactto crystal rod (rod-like structure of glial). was contacted with gastricshield. The intestine was constituted of inner tube and outer tube. According to the structure, the intestine could be divided into four parts: foregut, midgut, hindgut and rectum. The foregut was joined to the stomach. Both the crystal rod and the foregut were wrapped into one tube during getting out of the stomach, and twisted in the visceral mass. The midgut was constituted from the suddenly small part of foregut to the swelled part of hindgut. The above two parts were joined by capsule, which was full of food and also twisted in the visceral mass. The hindgut was began with the swelled part through into the heart, which was constitute of one capsule filled with food. The rectum was from the heart to anus, and wrapped in a pipe which was full of food and waste. The anus was located at the posterior adductor muscle and the outlet pipe.The organization structure of digestive system of Hyriopsis cumingii.The liver, as digestive diverticula, was the most important digestive organs, which was composed of a number of branches of small blind tubes by biopsy technique. According to the structure and function, the liver could be divided into common hepatic duct and tubule. The enteron was constituted of mucosa, submucosa and serosa, and did not have muscle. However, there was a muscle layer outside of the intestinal tract, which was gradually thickened from the beginning to the end. Mucous layer was constituted of long cylindrical cells with cilia. In different parts of the enteron, the structure of mucosa layer were slightly different from that of submucosa layer. The mucosa epithelium of hindgut was irregularly rough. The gastric mucosa epithelium was little thicker than intestinal mucosa epithelium. Besides, the intestinal epithelium contained caliciform cells, which could secrete mucus, especially in the hindgut.The activities and optimal pH values of protease, amylase and cellulase were determined by using Folin-phenol, iodine-starch colorimetry and DNS techniques in the liver, stomach, foregut, midgut, hindgut and rectum. The results showed that the protease activity was from high to low as follows: stomach> liver> foregut> midgut> hindgut> rectum. The optimal pH value of all organs was 7.0, except the rectum 7.5. The amylase activity was from high to low as follows: stomach > hindgut> liver> midgut> foregut> rectum. The optimal pH value of liver, stomach and hindgut was 7.5, while that of foregut, midgut and rectum was 7.0. The cellulose activity was from high to low as follows: stomach> midgut> liver> hindgut> foregut> rectum. The optimal pH value of liver is 5.0, while that of the others was 4.6. Compared test was showed that activities of protease, amylase, cellulase in two groups were significantly different under different conditions of live algae.更多还原