Characterization of chymotrypsin activity during early ontogeny of larval red drum (Sciaenops ocellatus)

The temporal evolution of chymotrypsin activity during early ontogeny of laboratory reared red drum larvae was accomplished using a combination of biochemical assays and electrophoretic methods (substrate SDS-PAGE). Optimal functional conditions for chymotrypsin were also determined. Chymotrypsin activity was first detected prior to the onset of exogenous feeding. Total chymotrypsin activity increased with age and standard length. Specific activity was greatest on day 10 post-hatch. Maximal chymotrypsin activity was observed at 50 °C, pH 7.8, and Ca²⁺ concentration of 25 mM. Using substrate gel electrophoresis and specific inhibitors the molecular weight of red drum chymotrypsin was estimated to be 26–27 kD. Our results indicate that the digestive system of red drum larvae is capable of alkaline proteolysis before first feeding and suggest that chymotrypsin may have potential as an indicator of nutritional condition.     

羊消化道寄生虫种类及防治措施

羊消化道的寄生虫病较多,不仅能不同程度地影响羊只的生长发育,降低生产性能,严重的还能造成羊只死亡,对养羊业危害较为严重。笔者概述了羊消化道寄生虫种类及不同地区、季节、年龄羊消化道寄生虫的感染情况,并介绍不同羊消化道寄生虫常用的驱虫药及防治策略。     

甜菜碱对热应激肉鸡生长性能、十二指肠消化酶活性及盲肠微生物区系的影响

本试验通过在饲粮中添加不同剂量的甜菜碱研究其对热应激肉鸡生长性能、十二指肠消化酶活性及盲肠微生物区系的影响。选取270只14日龄爱拔益加(AA)肉鸡随机分成6组:常温组、热应激组,常温+0.1%甜菜碱组、热应激+0.1%甜菜碱组、热应激+0.2%甜菜碱、热应激+0.4%甜菜碱组。热应激肉鸡饲养在(32±1)℃的高温环境中。每组3个重复,每个重复15只。预试期7 d,正试期21 d。结果表明:1)饲粮添加甜菜碱可极显著增加28~42日龄热应激肉鸡的体重(P<0.01),极显著降低22~35日龄肉鸡料重比(P<0.01);2)除添加0.1%和0.2%甜菜碱饲粮对28日龄热应激肉鸡胰蛋白酶活性无显著影响(P>0.05)和添加0.1%甜菜碱对35日龄热应激肉鸡淀粉酶活性无显著影响(P>0.05)外,不同浓度的甜菜碱均能显著或极显著增加28、35、42日龄热应激肉鸡十二指肠胰蛋白酶、淀粉酶和胰脂肪酶活性(P<0.05或P<0.01);3)饲粮添加甜菜碱极显著提高了28、35、42日龄热应激肉鸡盲肠内乳酸杆菌的数量(P<0.01),极显著降低了产气荚膜梭菌的数量(P<0.01)。由此可见,热应激状态下,在基础饲粮中添加甜菜碱可改善AA肉鸡生长性能,提高十二指肠消化酶的活性,维持盲肠内微生物区系平衡,从而减轻热应激对肉鸡的危害。     

复合酸化剂在断奶仔猪饲料中的应用研究

将96头断奶1周杜×长×大仔猪(35日龄)随机分成4组,每组24头,分为4个重复,每个重复6头,进行28d试验。试验采用单因子完全随机化设计,共设4个处理,包括对照组和3个试验组,基础日粮相同,对照组为不添加酸化剂的基础日粮,试验1、2、3组分别为添加0.10%、0.15%和0.20%复合酸化剂的基础日粮。结果表明:添加0.15%和0.20%复合酸化剂均能显著提高断奶仔猪日增重、小肠胰蛋白酶、淀粉酶活性及盲肠乳酸杆菌数量,降低胃内容物pH,以添加0.15%复合酸化剂最好,能够显著降低料肉比和盲肠大肠杆菌数量。     

光照对中国对虾稚虾3种消化酶活力的影响

在实验室条件下研究光照(光照周期、光照强度和光色)对中国对虾(Fenneropenaeus chinensis)稚虾3种消化酶(蛋白酶、淀粉酶和脂肪酶)活力的影响。在本实验条件下,主要结果如下:(1)4种光照周期下,对虾3种消化酶的活力差异不显著(P>0.05);(2)在完全黑暗、6μmol.m-2.s-1、30μmol.m-2.s-1和110μmol.m-2.s-1光照强度下,对虾蛋白酶的活力分别为0.361 U.mg-1(protein)、0.081 U.mg-1(protein)、0.088 U.mg-1(protein)和0.273 U.mg-1(protein),完全黑暗和110μmol.m-2.s-1下的活力显著高于其他两个光照强度(P<0.05),且两者间的差异达到显著水平(P<0.05);中国对虾淀粉酶的活力分别为0.386 U.mg-1(protein)、0.095 U.mg-1(protein)、0.111 U.mg-1(protein)和0.315 U.mg-1(protein),完全黑暗和110μmol.m-2.s-1条件下的活力显著高于其他两个光照强度(P<0.05),两者间的差异亦达到显著水平(P<0.05);对虾脂肪酶的活力分别为0.147×10-2U.mg-1(protein)、0.150×10-2U.mg-1(protein)、0.170×10-2U.mg-1(protein)和0.183×10-2U.mg-1(protein),完全黑暗和110μmol.m-2.s-1条件下的活力差异达到显著水平(P<0.05);(3)不同光色下,对虾蛋白酶和淀粉酶的活力差异不显著(P>0.05),脂肪酶的活力则存在一定的差异,蓝光和黄光下,对虾脂肪酶的活力分别为0.093×10-2U.mg-1(protein)和0.107×10-2U.mg-1(protein),显著高于白光和绿光下的活力(P<0.05),但蓝光组和黄光组间的差异不显著(P>0.05)。     

松江鲈鱼初期胚后发育阶段消化系统组织学的初步研究

实验通过对松江鲈鱼(Trachidermus fasciatus Heckel)仔鱼的消化道进行从口腔到尾部的连续切片,观察其消化道的组织学结构。结果表明:①松江鲈鱼仔鱼在出膜后1d与2d的消化道组织结构简单,肠腔部分位置堵塞,未见畅通,仔鱼靠自身的卵黄囊进行营养。②出膜3d后的松江鲈鱼仔鱼消化道畅通,可进行主动摄食。了解到这一情况,并根据其当时精确的口径大小,可为解决松江鲈鱼仔鱼开口时间与选择合适开口饵料提供理论依据。     

中国对虾亲虾生殖周期中消化酶活性及组织生化成分的变化

叙述了中国对虾亲虾(海捕亲虾与池养亲虾)在生殖周期中肝胰腺、中肠的消化酶活性及卵巢、肝胰腺、血淋巴生化成分的研究结果。蛋白酶、脂肪酶在卵巢成熟的Ⅳ期前活性较高，临产卵时(Ⅴ期)活性明显下降，而且海捕亲虾与池养亲虾具有相同的变化趋势；中国对虾卵巢、肝胰腺和血淋巴的蛋白质和脂肪含量随性腺发育有不同的变化规律，其中总蛋自在这几种组织中均随性腺发育含量增加，至Ⅳ期(肝胰腺)和Ⅴ期(卵巢、血淋巴)达到高峰值；卵巢的总脂和甘油三酯从发育Ⅰ期-Ⅴ期随着性腺指数的增长而有规律的上升，但肝胰腺脂肪含量在卵巢发育初期(Ⅰ期-Ⅱ期)未见明显变化，Ⅱ期以后，肝胰腺脂肪含量逐渐下降，当卵巢脂肪含量达到最高值时，肝胰腺脂肪含量正好下降到最低点。同时，还对中国对虾卵巢发育过程中蛋白质和脂肪的积累问题进行了分析和讨论。     

Digestive enzyme activity of the red porgy (Pagrus pagrus, L.) during larval development under culture conditions

The ontogenic development of the main digestive enzymes (proteases, amylase and lipase) in the red porgy, Pagrus pagrus, larvae was assayed during the larval development. The green water technique was carried out for larval rearing and whole‐body homogenates were used for enzymatic assays in triplicate. Significant alterations in specific activities of all digestive enzymes measured during the period of this study were mostly related to metamorphosis and weaning. Trypsin‐ and chymotrypsin‐specific activities were first detected on day 3, together with opening of the mouth, and slightly increased until 25 days after hatching (DAH). After this period, the specific activities of these enzymes slightly decreased. Pepsin was first detected on day 28, concurrent with stomach formation, and a sharp increase was observed until 30 DAH. A slight decrease was measured from this date until the end of the experiment. Both amylase and lipase were measured for the first time on days 2 and 4 respectively, and the specific activities of these enzymes showed similar patterns during the first week of the study. Then, slight variations were observed until 30 DAH and while lipase‐specific activity declined, an increase in the specific activity of amylase was found until the end of the experiment. It is concluded that the variations observed in the specific activity of digestive enzymes were related to either metamorphosis, such as the formation of the stomach (28 DAH), or to changes in food composition. The profile of the developmental pattern of the main digestive enzymes detected in P. pagrus is similar to that described for other Sparid species.     

Presence and ontogeny of intestinal and pancreatic phospholipase A2-like proteins in the Red Sea bream,Pagrus major. An immunocytochemical study

We have studied the location and the ontogeny of the digestive enzyme, phospholipase A₂ (PLA₂) immunohistochemically in the adult and larvae/juvenile of the red sea breamPagrus major by using an antiserum against theNaja naja venom PLA₂. The antiserum reacts with at least one enzyme among the PLA₂s purified from the fish hepatopancreas or intestine. Although the reactivities were comparatively low, it labelled zymogen granules of the pancreatic acinar cells and secretory materials of certain epithelial cells in the depths of epithelial crypts in the pyloric caeca of the adult. The immunoreactivities of PLA₂s were investigated in the viscera of larvae and juveniles of the 0 to 85^th day after hatch. In the larvae of the 13^th day, accumulation of PLA₂-positive zymogen granules in the pancreatic acinar cells were first recognized by the immunostaining. The intensity of the labelling subsequently became stronger and dramatically increased between the 20^th and 30^th day. This increase appeared to be one of the physiological changes associated with the transition to a new benthic life as juveniles. Lack of PLA₂ in the pancreas before the 13^th day may suggest the possibility that larvae utilized exogenous PLA₂, inherent in their prey, to digest the phospholipids. On the other hand, no reactivity was found in the intestine until the 85^th day.     

Stimulating effects of pond water on digestive enzyme activity in the Pacific white shrimp, Litopenaeus vannamei (Boone)

Crude enzyme extracts were obtained from the digestive glands of Pacific white shrimp, Litopenaeus vannamei (Boone), reared in oligotrophic well water and eutrophic shrimp pond water to compare digestive enzyme activity between the two groups. Specific activities of serine protease, collagenase, amylase, cellulase, lipase and acid phosphatase were significantly higher (P < 0.01) in pond water‐reared shrimp (PW shrimp) than in well water reared‐shrimp (WW shrimp). For most enzymes assayed, specific activity was more than two times higher in PW shrimp, and cellulase activity was over six times higher. In contrast, chitinase activity was significantly higher (P < 0.001) in WW shrimp. Higher specific activity of most digestive enzymes in PW shrimp was probably due to natural productivity in the pond water that served as a source of organic substrates, and this increased activity may contribute to the growth‐enhancing effect of shrimp pond water.