| Subordinated to Crustacea, Decapoda, Varunidae, Chinese mitten crab(Eriocheir sinensis) is so-called ―da zha xie‖ or ―he xie‖, which becomes a kind of healthy economic crabs cultured in fresh water in our country. Not only its meat is delicate and delicious but also it has a high nutritional and medicinal value, it becomes the very popular healthy food and high-quality gift. With the increasing demand of the market, the proportion of artificial breeding and yield increased in recent years, the Chinese mitten crab annual output from 1075 tons in 1993, increased to750 thousand tons in 2014. A lot of research on artificial breeding, feeding mode and breeding &reproduction of Chinese mitten crab has been carried out by scholars such as Wang Wu and Cheng Yongxu. However, the basic research on gastric and intestinal motility of Chinese mitten crab is still relatively scarce. In this study, the preliminary research of intestinal motility related neurons, intestinal motility and gastric emptying of Eriocheir sinensis was carried out as the main content.The intestinal wall layers of Chinese mitten crab were separated and stretched for the first time using the whole mount stretch preparation technologies to clarify the distribution and morphological characteristics of AchE and NOS positive neurons throughout the Eriocher sinensis midgut and hindgut using histochemistry, and to analysis the content of Ach and NO and Na+-K+-ATP enzyme activity of midgut and hindgut in Eriocher sinensis by biochemical method. As far as we know, this is the first document which whole-mount preparations of intestinal walls of midgut and hindgut in Eriocher sinensis were respectively made and stained with H&E. The effects of temperature on the feeding rate, the time of food intake and the effects of different feeding modes on the feeding rhythm of juvenile crab larvae were studied and analyzed at the same time in this study.1 The Histological comparison of stretches of hindgut and midgut in Chinese mitten crab using H.E stainingThe midgut and hindgut of Chinese mitten crab were stratified stretched, and muscle layers, submucosa and basement-membrane layers were successfully obtained. Using H.E staining, The results showed that muscle layer of midgut and hindgut was made of smooth muscle, compared to the hindgut, the midgut muscle layer consisted of thin muscle fiber with obvious muscle fiber spacing, muscle fiber of midgut arranged closely and thickly. Submucosas of midgut and hindgut were made up of various cells. These cells were more abundant in the submucosa of hindgut than midgut, sized 2-10μm. Without obvious cell structure, basement-membrane of midgut was thiner than that of hindgut,basement-membrane was thin and transparent,which is similarly to membranous-like.2 Observation of AchE, NOS and Cajal positive neurons and a comparison of Ach and NO content and Na+-K+-ATP enzyme activity of midgut and hindgut in Eriocher sinensisTo clarify the distribution and morphological characteristics of AchE and NOS positive neurons throughout the midgut and hindgut of Eriocher sinensis using histochemistry, and to analysis the content of Ach and NO and Na+-K+-ATP enzyme activity of midgut and hindgut in Eriocher sinensis by biochemical method. The results showed that AchE-positive neurons and NOS-positive neurons distributed densely only in the submucosa, especially in hindgut. The AchE-positive neurons were colored brown, which ranged from 3 to 10 μm in size. The shape of AchE-positive neurons in midgut were various, most of them were round, oval or spindle shape. The NOS-positive neurons with different size and shape were colored blue. A few of these cells with cytoplasmic projections could be observed. ICC The content of Ach and NO and Na+-K+-ATP enzyme activity in midgut had obviously different from that in hindgut. The content of Ach and NO in midgut were significantly lower than those in hindgut(P<0.05). However, Na+-K+-ATP enzyme activity of midgut(1.12±0.17μmol Pi/mgprot/h) was significantly higher than those of hindgut(0.62±0.18μmol Pi/mgprot/h)(P<0.05).3 Effects of temperature on the food advance speed and gastric emptying time of the intestinal tract of Chinese mitten crabFour temperature groups(17℃,20℃,25℃,30℃)were carried out to research the effects of temperature on the intestinal propulsion rate and gastric emptying time of the intestinal tract of Chinese mitten crab by taking notes of the food advance of every time point. The results showed that,The mean retention time(MRT) in the stomach of male crabs is longer than the female crabs, Food didn’t run to the midgut in male crabs, and female crabs had run to the midgut in 1h. Male crabs intestinal propulsion time is shorter. 80% of female crabs has been synchronized gastric emptying in about 7 h, and male crab in 6.5 hours appear synchronous emptying. From 16℃ to 25℃. With water temperature rised, the Chinese mitten crabs food digestion rate had increased, a corresponding reduction in the gastric emptying time. However, when the water temperature reached to 30℃, the Chinese mitten crab gastric emptying time increased, emptying time of 20 ℃ and 25 ℃ groups was significantly faster(P<0.05), and 16 degrees and 30 ℃ group, intestinal food promotion was significantly lower than 20 ℃ and 25 ℃ group(P<0.05); Female juvenile crabs gut promote rate was generally higher than male juvenile crab. The results showed that 20- 25 ℃ was the suit temperature for gastric emptying of Chinese mitten crab. |
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