中华绒螯蟹幼体消化酶活力与氨基酸组成的研究

本文对中华绒螯蟹（Ｅｒｉｏｃｈｅｉｒｓｉｎｅｎｓｉｓ）各期幼体的消化酶活力与氨基酸组成进行了分析。实验结果表明，在中华缄螯蟹幼体发育过程中，五种消化酶活力表现出三种变化模式。胃蛋白酶、类胰蛋白酶和淀粉酶活力在食性转换过程中出现较明显变化，其中胃蛋白酶和类胰蛋白酶活力在状幼体期达到最大值；淀粉酶活力在状幼体期达最大值；纤维素酶和脂肪酶活力极微。氨基酸含量随着幼体发育逐渐增加，在必需氨基酸中以亮氧酸含量最高，色氨酸含量最低；非必需氨基酸中含量最高者为谷氨酸，最低者为胱氨酸。同时单个必需氨基酸含量与必需氨基酸总量的比值（Ａ／Ｅ）在幼体不同发育阶段略有差异，但基本趋于一致。     

克氏原螯虾幼体发育时期消化酶活力及氨基酸含量研究

采用生物化学方法对克氏原螯虾各期幼体消化酶活力与氨基酸组成进行了分析。实验结果显示,在克氏原螯虾幼体发育过程中,五种消化酶活力(胃蛋白酶、类胰蛋白酶、淀粉酶、纤维素酶和脂肪酶)表现出两种变化模式:胃蛋白酶和类胰蛋白酶在幼体发育Ⅱ龄幼体期和Ⅳ龄幼体期活力较高,其中Ⅳ龄幼体期该两种酶活力最高;淀粉酶、纤维素酶和脂肪酶活力为先增高后降低,在Ⅲ龄幼体期,三种酶的活力达到最高,但与Ⅳ龄幼体期的酶活力比较无显著差异。总氨基酸含量在幼体发育早期逐渐降低,幼体发育至Ⅲ龄幼体期,其氨基酸含量最低,Ⅳ龄幼体期又有所增加。在测定的所有氨基酸中谷氨酸含量最高,必需氨基酸中赖氨酸含量最高,单个必需氨基酸含量与必需氨基酸总量的比值(A/E)在整个胚胎发育过程中的变化趋于一致。     

罗氏沼虾幼体及仔虾消化酶活力的研究

以酶学分析方法对罗氏沼虾幼体及仔虾4种消化酶的活力进行研究。结果表明：罗氏沼虾早期个体消化酶类胰蛋白酶、胃蛋白酶和脂肪酶比活力均为蚤状幼体I朗(Z1)＜蚤状幼状IV期(z4)＜蚤状幼体x期(Zlo)＜仔虾I—Ⅱ期(PI—Ⅱ)，各期的类胰蛋白酶比活力明显低于胃蛋白酶；淀粉酶比活力为z＜P期，在pH值2—9．8的范围内，蛋白酶活性出现2个高峰分别为pH2．6—3．2和pH5．6—6．25淀粉酶最适pH值为5．2—5．8，呈弱酸性。     

中华绒螯蟹胚胎发育过程中的消化酶活力及氨基酸组成

采用生物化学方法测定了中华绒螯蟹(Eriocheir sinensis)胚胎发育过程中7个发育期的5种水解酶(类胰蛋白酶、胃蛋白酶、淀粉酶、脂酶和纤维素酶)活力和氨基酸的组成。结果表明，胚胎发育各阶段消化酶活力及氨基酸组成的变化与其发育关系密切。在整个胚胎发育过程中，类胰蛋白酶、胃蛋白酶和纤维素酶的活力呈“高-低-高”的变化趋势，脂酶则呈现逐渐上升的趋势，而淀粉酶的变化趋势不明显。但在原蚤状幼体期，5种酶的活力均显著升高，这与孵化后幼体开口摄食的自身调控机理有关。可溶性蛋白质的含量呈“低-高-低”的变化趋势，明显与相关酶的活力有关。氨基酸含量在前6期变化不大，在原蚤状幼体期显著下降。所有氨基酸中，谷氨酸的含量最高；必需氨基酸中以亮氨酸的含量最高，并且单个必需氨基酸含量与必需氨基酸总量的比值(A／E)在胚胎发育不同阶段略有差异，但基本趋于一致。     

三疣梭子蟹幼体消化酶活力及氨基酸组成的研究

在三疣梭子蟹幼体发育过程中，五种消化酶活力表现出三种变化模式，其中胃蛋白酶和类胰蛋白酶活力呈上升趋势，而且在蚤状幼体Ⅰ期时就较高，淀粉酶活力逐渐减小，纤维素酶和脂肪酶活力极微。氨基酸含量随幼体发育逐渐增加。必需氨基酸中以亮氨酸含量最高，色氨酸含量最低；非必需所基酸中含量最高者为谷氨酸，最低者为胱氨酸。同时单个必需氨基酸含量与必需氨基酸总量的比值（Ａ／Ｅ）在幼体不同发展阶段略有差异，但基本趋于一致。     

甲壳动物幼体消化酶研究进展

通过研究近年来国内外学者关于甲壳动物幼体消化酶方面的研究现状,发现目前已测定出甲壳动物幼体消化酶的种类主要有：蛋白酶、胰蛋白酶、羧肽酶A、羧肽酶B、氨肽酶、胶原酶、弹性蛋白酶、胃蛋白酶、糜蛋白酶、酯酶、脂肪酶、淀粉酶、纤维素酶、几丁质酶、麦芽糖酶、蔗糖酶、昆布多糖酶等种类,初步归纳了甲壳动物幼体主要消化酶的分子量、最适pH和最适温度;分析了幼体发育过程中消化酶活力变化模式以及与食性的关系,并采用淀粉酶/蛋白酶活力（A/P）比值或淀粉酶/类胰蛋白酶（A/T）比值作为甲壳动物幼体的食性指标;观察了幼体消化器官的发育,阐明幼体消化酶的合成与分泌不仅由遗传控制、中肠腺发育程度等因子决定,而且还与饲料的营养水平有关,提出采用幼体消化酶对饲料组成的适应性研究幼体营养需求的新途径.[中国水产科学,2006,13（3）：492-501]     

温度对中国对虾幼体生长发育与消化酶活力的影响↑（*）

本文通过计数、称重和酶学分析的实验方法研究温度对中国对虾幼体生长发育与消化酶活力的影响。实验表明，温度对中国对虾各期幼体的存活率、变态率和增重量及三种消化酶活力有明显的影响，呈一个峰值变化。在实验温度范围内随着幼体发育，温度对存活率的影响逐渐减弱，对增重量影响逐渐增大。还表明温度对其各期幼体消化酶活力的影响与食性有关，各期幼体的三种消化酶活力对环境温度有各自的适应性，适温范围为２２－２８℃，而且在幼体发育过程中，其适宜温度逐渐上升。     

凡纳对虾(Litopenaeus vannamei Boone)幼体淀粉酶(Amylase)和脂肪酶(Lipase)活力的研究

本文以酶学分析方法测定了凡纳对虾状幼体,糠虾和仔虾三个发育期淀粉酶和脂肪酶的活力。实验结果表明,糠虾期淀粉酶比活力显著高于状幼体和仔虾两期(P<0.05);脂肪酶比活力状幼体显著高于糠虾幼体(P<0.05)。在食性转化过程中,凡纳对虾幼体消化酶活力与其食性相适应,不同发育阶段消化酶调节机制不同。     

大黄鱼发育进程中消化酶的活力变化

不同发育阶段大黄鱼(Pseudosciaena crocea)样品体重30～500g,取自厦门海区网箱养殖区。以酶学分析方法测定大黄鱼发育进程中胃蛋白酶、类胰蛋白酶、淀粉酶、脂肪酶4种消化酶的活力。结果表明,在大黄鱼发育进程中,对蛋白的整体消化能力始终较强;4种消化酶活力表现出2种变化模式,其中胃蛋白酶和类胰蛋白酶活力逐渐降低,而淀粉酶和脂肪酶活力呈上升趋势。胃蛋白酶、类胰蛋白酶、淀粉酶和脂肪酶的比活力随鱼体重的变化分别遵循回归方程Y=34．89／X 0．050;Y=53．36／X 0．29;Y=-22．38／X 1．13和Y=-1．35／X 0．13。初步认为,在大黄鱼发育过程中,150g体重为其生长发育的转折点,这一阶段各种消化酶的变化可反映其食性的变化情况,本研究旨为大黄鱼配合饲料的研制与开发提供基础依据。     

卵巢发育过程中河蟹肝胰腺消化酶活力的变化

研究了河蟹卵巢发育过程中肝胰腺的5种消化酶活力的变化。测定结果表明：随着卵巢发育的逐渐成熟，河蟹肝胰腺中的胃蛋白酶、类胰蛋白酶、纤维素酶、淀粉酶活力变化都是先升后降，Ⅲ2期达到峰值，其中淀粉酶比活力较高，平均高达152．855U／mg蛋白，脂肪酶比活力极低，平均仅为0．020U／mg蛋白。肝胰腺消化酶活力的大小和变化与河蟹卵巢发育过程中的营养需要和物质转换密切相关。     

罗氏沼虾胚胎发育期主要消化酶和同工酶特性

采用生物化学方法分别测定了罗氏沼虾胚胎发育期5种消化酶:胃蛋白酶、类胰蛋白酶、淀粉酶、纤维素酶和脂肪酶的比活力,测定了6种同工酶:酯酶(EST)、苹果酸脱氢酶(MDH)、谷氨酸脱氢酶(GDH)、碱性磷酸酶(ALP)、乳酸脱氢酶(LDH)和淀粉酶(AMY)在成熟卵细胞和胚胎发育时期的表达特征。结果显示:5种消化酶的活力表现出两种变化趋势,即胃蛋白酶、类胰蛋白酶、淀粉酶和纤维素酶的酶活力呈现出“高—低—高”的变化趋势,而脂肪酶活力则呈现出下降的变化趋势。6种同工酶酶谱则随胚胎发育渐趋复杂,酶活性随之增强。研究表明,所测定的消化酶以及同工酶在罗氏沼虾受精卵期均已表现出酶活性,此阶段为卵源性的酶;原肠期是胚胎发育中一个较为重要的时期,胚胎内酶基因表达能力开始逐渐增强,开始合成一些酶类,为胚胎发育后期利用卵黄物质提供了保证。消化酶以及同工酶对卵黄物质的利用和胚胎发育的物质代谢起重要作用。     

Development of digestive enzyme activity in spotted rose snapper,Lutjanus guttatus (Steindachner, 1869) larvae

We describe digestive enzyme activity during the larval development of spotted rose snapper, Lutjanus guttatus. Trypsin, chymotrypsin, leucine aminopeptidase, pepsin, amylase, lipase, and acid and alkaline phosphatase activities were evaluated using spectrophotometric techniques from hatching through 30 days. The spotted rose snapper larvae present the same pattern of digestive enzyme activity previously reported for other species in which pancreatic (i.e., trypsin, chymotrypsin, amylase, and lipase) and intestinal (i.e., acid and alkaline phosphatases and leucine aminopeptidase) enzymatic activities are present from hatching allowing the larvae to digest and absorb nutrients in the yolk-sac and live prey by the time of first feeding. The digestive and absorption capacity of the spotted rose snapper increases during the larval development. A significant increase in individual activity of all enzymes occurs at 20 DAH, and around 25 DAH, the juvenile-type of digestion is observed with the appearance of pepsin secreted by the stomach, suggesting that maturation of the digestive function occurs around 20–25 DAH. Our results are in agreement with a previous suggestion that early weaning may be possible from 20 DAH. However, the patterns of enzymatic activities reported in our study should be considered during the formulation of an artificial diet for early weaning of the spotted rose snapper.     

Ontogenetic development of digestive functionality in golden pompano Trachinotus ovatus (Linnaeus 1758)

Ontogenetic development of the digestive system in golden pompano (Trachinotus ovatus, Linnaeus 1758) larvae was histologically and enzymatically studied from hatch to 32 day post-hatch (DPH). The development of digestive system in golden pompano can be divided into three phases: phase I starting from hatching and ending at the onset of exogenous feeding; phase II starting from first feeding (3 DPH) and finishing at the formation of gastric glands; and phase III starting from the appearance of gastric glands on 15 DPH and continuing onward. The specific activities of trypsin, amylase, and lipase increased sharply from the onset of first feeding to 5–7 DPH, followed by irregular fluctuations. Toward the end of this study, the specific activities of trypsin and amylase showed a declining trend, while the lipase activity remained at similar levels as it was at 5 DPH. The specific activity of pepsin was first detected on 15 DPH and increased with fish age. The dynamics of digestive enzymes corresponded to the structural development of the digestive system. The enzyme activities tend to be stable after the formation of the gastric glands in fish stomach on 15 DPH. The composition of digestive enzymes in larval pompano indicates that fish are able to digest protein, lipid and carbohydrate at early developmental stages. Weaning of larval pompano is recommended from 15 DPH onward. Results of the present study lead to a better understanding of the ontogeny of golden pompano during the larval stage and provide a guide to feeding and weaning of this economically important fish in hatcheries.     

不同阶段三疣梭子蟹保护酶及消化酶活性研究

以三疣梭子蟹(Portunus trituberculatus)的幼蟹、雌性成蟹及抱卵雌蟹为研究对象,分别测定比较了野生和养殖蟹肌肉中的超氧化物歧化酶(SOD)及肝胰腺中的胃蛋白酶、脂肪酶、淀粉酶活性,旨在揭示三疣梭子蟹不同生长阶段的消化酶和SOD酶活性的变化规律,及其与生长环境之间的关系。结果表明:(1)幼蟹、成蟹和抱卵蟹的SOD酶均表现为野生蟹显著高于养殖蟹(P<0.05);野生成蟹的脂肪酶和胃蛋白酶活性亦显著高于养殖蟹,是养殖蟹的2.5倍以上。因此,养殖蟹的机体健康水平、免疫保护和抗应激能力不及野生蟹,尤以幼蟹阶段SOD酶活性最低,抗逆境力最差。(2)野生和养殖幼蟹的淀粉酶活性分别为(1.57±0.09)U.mg-1和(2.61±0.01)U.mg-1,显著高于成蟹和抱卵蟹(P<0.05);野生和养殖成蟹的胃蛋白酶活性分别为(5.83±0.45)U.mg-1和(2.77±0.10)U.mg-1,显著高于幼蟹和抱卵蟹(P<0.05),是幼蟹和抱卵蟹的2～3倍;脂肪酶活性以养殖抱卵蟹最高,野生成蟹次之;消化酶活性变化与蟹的生长阶段及食性转变相关。     

不同饵料对奥尼罗非鱼仔稚鱼生长发育及消化酶活力的影响

将初始体质量为(0.006±0.0005)g的仔鱼,随机分为4组,每组3个平行,分别投喂4种饵料:人工配合饵料、轮虫、蛋黄和轮虫+人工配合饵料.试验周期为28 d.结果表明,(1)轮虫+人工配合饵料和人工配合饵料组生长较快,特定生长率分别为0.014 %/d和0.013 %/d, 绝对生长率达到0.150、0.142 g/d,二组差异不显著(P>0.05);蛋黄组生长最慢,与其他各组差异显著(P<0.05).(2)轮虫+人工配合饵料与轮虫组仔稚鱼的成活率达到90.3%和 89.7%,大部分个体发育进入幼鱼阶段,二组差异不显著(P>0.05);蛋黄组存活率较低,只有40.7%,与其他各组差异显著(P<0.05).(3)投喂不同饵料对奥尼罗非鱼仔稚鱼的消化酶具有显著影响,蛋黄组的淀粉酶和脂肪酶活力显著高于其他各组(P<0.05);轮虫+人工配合饵料组的胃蛋白酶活力较高,天然饵料(轮虫)组较低.     

Developmental changes in digestive enzyme activity in American shad, <Emphasis Type="Italic">Alosa sapidissima</Emphasis>, during early ontogeny

In order to assess the digestive physiological capacity of the American shad Alosa sapidissima and to establish feeding protocols that match larval nutritional requirements, we investigated the ontogenesis of digestive enzymes (trypsin, amylase, lipase, pepsin, alkaline phosphatase, and leucine aminopeptidase) in larvae, from hatching to 45 days after hatching (DAH). We found that all of the target enzymes were present at hatching, except pepsin, which indicated an initial ability to digest nutrients and precocious digestive system development. Trypsin rapidly increased to a maximum at 14 DAH. Amylase sharply increased until 10 DAH and exhibited a second increase at 33 DAH, which coincided with the introduction of microdiet at 30 DAH, thereby suggesting that the increase was associated with the microdiet carbohydrate content. Lipase increased until 14 DAH, decreased until 27 DAH, and then increased until 45 DAH. Pepsin was first detected at 27 DAH and then sharply increased until 45 DAH, which suggested the formation of a functional stomach. Both alkaline phosphatase and leucine aminopeptidase markedly increased until 18 DAH, which indicated intestinal maturation. According to our results, we conclude that American shad larvae possess the functional digestive system before mouth opening, and the significant increases in lipase, amylase, pepsin, and intestinal enzyme activities between 27 and 33 DAH suggest that larvae can be successfully weaned onto microdiets around this age.