; 黄条; 五条; 消化酶活力; 分布特征" />
  渔业科学进展  2022, Vol. 43 Issue (6): 102-110  DOI: 10.19663/j.issn2095-9869.20211023001
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引用本文 

崔爱君, 徐永江, 柳学周, 姜燕, 李影, 王开杰, 方璐, 王滨. 3种养殖鱼消化相关酶活性的比较分析[J]. 渔业科学进展, 2022, 43(6): 102-110. DOI: 10.19663/j.issn2095-9869.20211023001.
CUI Aijun, XU Yongjiang, LIU Xuezhou, JIANG Yan, LI Ying, WANG Kaijie, FANG Lu, WANG Bin. Comparative Analysis of Digestive Enzyme Activities among Three Seriola Species[J]. Progress in Fishery Sciences, 2022, 43(6): 102-110. DOI: 10.19663/j.issn2095-9869.20211023001.

基金项目

国家重点研发计划项目(2019YFD0900901; 2018YFD0901204)、中国水产科学研究院基本科研业务费(2020TD47)、中国水产科学研究院黄海水产研究所基本科研业务费(20603022021011; 20603022020005)、国家海洋水产种质资源库项目和财政部和农业农村部:国家现代农业产业技术体系共同资助

作者简介

崔爱君,E-mail: aijun0218@126.com

通讯作者

徐永江,研究员,E-mail: xuyj@ysfri.ac.cn

文章历史

收稿日期:2021-10-23
3种养殖鱼消化相关酶活性的比较分析
崔爱君 , 徐永江 , 柳学周 , 姜燕 , 李影 , 王开杰 , 方璐 , 王滨     
中国水产科学研究院黄海水产研究所 青岛海洋科学与技术试点国家实验室深蓝渔业工程联合实验室 山东 青岛 266071
摘要:为深入了解鱼的消化生理特性,测定并比较分析了3种鱼[高体(Seriola dumerili)、黄条(Seriola lalandi)、五条(Seriola quinqueradiata)]的消化系统(胃、幽门盲囊、前肠、中肠、后肠和肝脏)中5种消化相关酶(胰蛋白酶、脂肪酶、淀粉酶、碱性磷酸酶和酸性磷酸酶)活性与组织分布特点。结果显示,3种鱼中5种消化相关酶主要分布在幽门盲囊、肝脏和肠道中。3种鱼胃组织中胃蛋白酶活性无差异。幽门盲囊中胰蛋白酶活性:黄条 > 高体 > 五条(P < 0.05),高体肝脏组织中胰蛋白酶活性显著高于其他2种鱼(P < 0.05);胃、中肠、后肠组织中α-淀粉酶活性:五条 > 黄条 > 高体(P < 0.05),幽门盲囊、前肠组织中α-淀粉酶活性:黄条 > 五条 > 高体(P < 0.05);胃、幽门盲囊组织中脂肪酶活性:黄条 > 五条 > 高体(P < 0.05),前肠、后肠、肝脏中脂肪酶活性:五条 > 黄条 > 高体(P < 0.05);3种鱼的酸、碱性磷酸酶活性组织分布趋势基本一致,其中,黄条幽门盲囊组织中酸、碱性磷酸酶活性最高(P < 0.05)。研究表明,3种鱼消化相关酶活性的组织分布特点基本一致,幽门盲囊是5种酶作用的主要靶器官,除胰蛋白酶外,高体其他4种酶活性均显著低于其他2种鱼,黄条幽门盲囊和肠道的5种酶活性显著偏高。结果可为揭示属鱼类的消化生理特性、研制适宜属鱼类消化特点和种特异性生长的高效专用配合饲料提供理论依据。
关键词高体    黄条    五条    消化酶活力    分布特征    
Comparative Analysis of Digestive Enzyme Activities among Three Seriola Species
CUI Aijun , XU Yongjiang , LIU Xuezhou , JIANG Yan , LI Ying , WANG Kaijie , FANG Lu , WANG Bin     
Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Joint Laboratory for Deep Blue Fishery Engineering of Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, Shandong 266071, China
Abstract: Seriola fish are long-distance migratory oceanic species inhabiting temperate and subtropical waters worldwide. Nine species have been identified in the genus Seriola, of which three species, namely S. lalandi, S. dumerili, and S. quinqueradiata, are found in the coastal waters of China. Seriola fish are large and fast-growing, and their flesh is highly favored by international consumers owing to its excellent taste, nutritional quality, and economic value. Moreover, Seriola fish are promising candidates for different culture modes, including deep-sea cages and recirculatory aquaculture systems. Since 2017, China has witnessed a great breakthrough in the seedling production of S. lalandi. Subsequently, in 2020, we achieved a breakthrough in the seedling production of S. quinqueradiata. The Seriola fish farming industry was developed in Liaoning, Fujian, and Shandong provinces, with the annual farming yield reaching approximately 20 000 tons.At present, ice trash is the primary feed for Seriola. However, excess trash fish feeding can produce a severe environmental pressure on coastal waters, which is not beneficial for sustainable development of the Seriola fish farming industry. Thus, there is an urgent need to develop specific commercial feed to solve bottleneck problems, including culture inefficiency and environmental pressure. The key to developing a specific commercial feed is to understand the digestive system structure and nutritional physiological characteristics of fish. Therefore, the distribution patterns of digestive enzyme activities in Seriola species warrant immediate attention.In December 2020, 3-year-old S. dumerili, S. lalandi, and S. quinqueradiata were collected from a cage culture base in Ningde, Fujian Province. The experimental fish were fed ice trash twice daily. Fish were healthy and vigorous. The total length and body weight of four fish of each species were measured, and their visceral structures were observed and recorded. The average length and weight were respectively (62.380±0.805) cm and (3.306±0.208) kg in S. dumerili; respectively (65.400±0.351) cm and (2.906±0.082) kg in S. lalandi; and respectively (74.640±1.041) cm and (4.622±0.258) kg in S. quinqueradiata. The stomach, intestines (to remove intestinal contents), and liver were collected, and the intestine was divided into the foregut, midgut, and hindgut according to the physiological curvature. Enzyme activity kits were purchased from Nanjing Jiancheng Reagent Company. The activities and distribution of five enzymes (trypsin, lipase, amylase, alkaline phosphatase, and acid phosphatase) in the digestive system (stomach, pyloric caeca, foregut, midgut, hindgut, and liver) of the three Seriola species studied were compared.In all Seriola species, trypsin activity was mainly distributed in the pyloric caeca and liver, α-amylase activity was mainly distributed in the pyloric caeca and midgut, lipase activity was evenly distributed in all tissues, alkaline phosphatase activity was mainly distributed in the pyloric caeca and intestinal tract, and acid phosphatase activity was mainly distributed in the pyloric caeca. Compared with the other two species, S. dumerili exhibited significantly higher trypsin activity in the liver; significantly lower α-amylase activity in the stomach, pyloric caeca, foregut, and hindgut; significantly lower lipase activity in the stomach, pyloric caeca, foregut, hindgut, and liver; significantly lower alkaline phosphatase activity in the stomach, pyloric caeca, foregut, midgut, and hindgut; and significantly lower acid phosphatase activity in the pyloric caeca, foregut, and midgut. Moreover, compared with the other two species, S. lalandi exhibited significantly higher trypsin and α-amylase activities in the pyloric caeca and foregut; significantly higher lipase activity in the stomach, pyloric caeca, and midgut; significantly higher alkaline phosphatase activity in the pyloric caeca and hindgut; and significantly higher acid phosphatase activity in the pyloric caeca. Furthermore, compared with the other two species, S. quinqueradiata exhibited significantly higher α-amylase activity in the stomach, midgut, and hindgut; significantly higher lipase activity in the foregut, hindgut, and liver; significantly higher alkaline phosphatase activity in the foregut and liver; and significantly higher acid phosphatase activity in the hindgut.In conclusion, the results of the present study indicate that the activities of the five enzymes studied show similar distribution patterns in the digestive system of the three Seriola species, with the pyloric caeca being the primary target organ for digestive enzymes. Comparative analysis revealed that the activities of all digestive enzymes, except trypsin, were significantly lower in S. dumerili; the activities of digestive enzymes in the pyloric caeca and intestines were significantly higher in S. lalandi; and the activities digestive enzyme in the pyloric caeca of S. quinqueradiata were significantly lower. These results may provide a theoretical basis for revealing the digestive physiological characteristics of Seriola species and developing highly efficient specific compound feed suitable for their digestion and growth.
Key words: Seriola dumerili    Seriola lalandi    Seriola quinqueradiata    Digestive related enzymes activity    Distribution pattern    

“十三五”以来,为拓展海水养殖新空间、养护近海渔业资源、保护近岸海域环境,我国大力发展深远海养殖,各种深远海大型养殖平台不断投入运行,但深远海养殖“养什么、怎么养”的问题日益凸显,成为深远海养殖持续健康发展的重要制约瓶颈。鱼是鲈形目(Perciformes)、鲹科(Carangidae)、属(Seriola)鱼类的统称,是一类体型大、生长快、全球水域广泛分布且长距离洄游的大洋性经济鱼类,目前,全世界已知的属鱼类共有9种(王波等, 2005),我国海域分布主要有3种,分别为高体(Seriola dumerili)、黄条(Seriola lalandi)和五条(Seriola quinqueradiata)。鱼具有较高的营养价值,是制作生鱼片、寿司等料理的上等食材,也是休闲渔业的重要培育对象,非常适宜深海网箱等深远海平台养殖。

本团队于2017年突破黄条苗种的繁育技术,近年来已实现黄条苗种规模化繁育,并于2020年突破五条亲鱼生殖调控和苗种繁育技术,为我国鱼养殖产业的快速发展提供了优质种苗的供给。目前,3种鱼的养殖已在我国辽宁、山东、福建等省兴起,养殖规模不断扩大。但是,在目前国内外鱼养殖过程中,饲料主要是冰鲜杂鱼,饲料的转化效率较低且大量投喂对养殖区的水域环境带来较大压力,亟需研发专用配合饲料来解决鱼养殖因鲜杂饵料投喂产生的潜在环境压力与饵料成本高的效益瓶颈问题。鱼类驯化养殖成功的关键是通过人为改变某些条件使其适应新的人工塑造的生存环境,其中包括适口配合饲料的研制与应用,而研制专用配合饲料的前提是了解鱼类的消化系统结构与营养生理特性(白晓慧等, 2007; 刘伟等, 2017)。目前,已有国内外学者关于环境条件对3种鱼消化酶活性影响的相关研究,不同温度和蛋白添加配比的饲料对五条消化酶活性具有显著影响(Kofuji et al, 2005),水温对黄条肠道消化时间、消化酶活性具有明显影响(Miegel et al, 2010),但关于3种鱼消化生理特征比较研究国内外尚未见报道。因此,本研究比较分析同一养殖条件下的3种鱼消化相关酶的分布特征与活性,揭示其消化生理特性与摄食食性的关系,旨在为研制适宜鱼消化特点和生长发育要求的高效专用配合饲料提供参考依据,助力我国鱼养殖产业的持续健康发展。

1 材料与方法 1.1 实验鱼来源

实验鱼于2020年12月取自福建东山富闽洋水产有限公司网箱养殖基地,网箱规格为10 m×10 m× 8 m,养殖密度为15 kg/m3。实验所取高体、黄条和五条养殖鱼为3龄鱼,均为海上采捕的野生苗种经人工养殖而成,实验鱼健康且活力好。样品采集前24 h停止投喂,养殖水温为18℃。实验鱼每天投喂2次,投喂率为鱼体重的5%,饵料为冰鲜玉筋鱼(Ammodytes personatus)。

1.2 样品采集与保存

采集3种鱼各4尾,测量全长、体重等数据,观察其内脏结构并做记录。采集的高体平均全长为(62.380±0.805) cm、平均体重为(3.306±0.208) kg,黄条平均全长为(65.400±0.351) cm、平均体重为(2.906±0.082) kg,五条平均全长为(74.640±1.041) cm、平均体重为(4.622±0.258) kg。实验鱼以MS 222 (100 mg/L)麻醉后,取出其胃、肠(清除肠道内容物)及肝脏,其中肠道按生理弯曲分为前肠、中肠和后肠,并用0.9%生理盐水冲洗干净,迅速放入液氮中冷冻保存,利用干冰运回实验室于–20℃冰箱保存。

1.3 消化酶活性测定

本实验蛋白浓度测定方法依照上海碧云天生物技术有限公司生产的Bradford蛋白浓度测定试剂盒(P0006)利用酶标仪(BIO-RAD iMARK,美国)进行操作;酶活性测定方法依照南京建成α-淀粉酶试剂盒(C016-1-1)、胰蛋白酶试剂盒(A080-2)利用分光光度计(普析TU-1810,中国)进行操作;胃蛋白酶试剂盒(A080-1-1)、脂肪酶试剂盒(A054-2-1)、碱性磷酸酶试剂盒(A059-2)和酸性磷酸酶试剂盒(A060-2)用酶标仪(BIO-RAD iMARK,美国)按照试剂盒说明书进行操作。

测定酶活性前将样品取出用0.9%的生理盐水冲洗,称取0.1 g组织使用灭菌解剖剪将其剪碎,加入900 µL样品匀浆介质,使用样品破碎仪(净信JXFSTPRP-24, 中国)使组织破碎匀浆,匀浆液于3500 r/min离心15 min后吸取上清液,于–20℃冰箱保存待用,15 d内测定完毕,测定脂肪酶、酸性磷酸酶、碱性磷酸酶活性时,再将10%浓度的上清液稀释至2%浓度待用。

胃蛋白酶活力单位定义:每毫克组织蛋白37℃每分钟分解蛋白生成1 μg酪氨酸相当于1个酶活力单位。胰蛋白酶活力单位定义:在pH 8.0、37℃条件下,每毫克蛋白中含有的胰蛋白酶每分钟使吸光度值(OD值)变化0.003即为1个酶活力单位。α-淀粉酶活力单位定义:组织中每毫克蛋白在37℃与底物作用30 min,水解10 mg淀粉定义为1个淀粉酶活力单位。脂肪酶活力单位定义:在37℃条件下,每毫升酶液在反应体系中与底物反应1 min,每消耗1 mmol底物为1个酶活力单位。碱性磷酸酶活力单位定义:每克组织蛋白在37℃与基质作用15 min产生1 mg酚为1金氏单位。酸性磷酸酶活力单位定义:每克组织蛋白在37℃与基质作用30 min产生1 mg酚为1金氏单位。

1.4 统计分析

采用SPSS 22.0软件对实验数据进行分析,运用单因子方差分析(one-way ANOVA)和Duncan检验法对同一种鱼不同组织和同一组织不同种鱼酶活性数据进行显著性差异分析和多重比较分析,设定差异显著性水平P值为0.05,所有数值均采用平均值±标准差(Mean±SD)表示。

2 结果 2.1 消化系统的外部形态比较

鱼胃与口咽腔连接,体积较大,胃壁较薄但弹性大,内褶皱较多,摄食后整个胃呈膨大的囊状。3种鱼均有细长条样幽门盲囊,其中,高体和五条幽门盲囊数量为60个左右,而黄条幽门盲囊数量为120个左右。肠道细长,前端与胃幽门底部联通,后端与泄殖孔联通,肠道有2个生理弯曲,在腹腔内呈“之”字形分布,整体包被在内脏的脂肪组织中,肝脏包覆于胃的上部。

2.2 蛋白酶活性的比较分析

3种鱼中,胰蛋白酶主要分布在幽门盲囊和肝脏中,肠道中活性较低(P < 0.05)。其中,幽门盲囊胰蛋白酶活性比较:黄条 > 高体 > 五条(P < 0.05);黄条肝脏中胰蛋白酶活性显著低于高体和五条(P < 0.05) (图 1)。3种鱼胃蛋白酶活性无显著差异(P > 0.05) (图 2)。

图 1 3种鱼各组织胰蛋白酶活性分布及比较 Fig.1 The distribution and comparative activity of trypsin in digestive system of three Seriola species GTS:高体;HTS:黄条;WTS:五条。不同大写字母表示同一组织不同种鱼间消化酶活性变化差异显著(P < 0.05),不同小写字母表示同一种鱼不同组织间酶活性变化差异显著(P < 0.05)。下同。 GTS: S. dumerili; HTS: S. lalandi; WTS: S. quinqueradiata; different capital letters indicate significant difference of digestive enzymes activities in same tissue from different species (P < 0.05); different lowercase letters indicate significant difference of digestive enzymes activities in different tissues from the same species (P < 0.05).
The same as below.
图 2 3种鱼胃组织胃蛋白酶活性比较 Fig.2 The comparative activity of pepsin in digestive system of three Seriola species
2.3 α-淀粉酶活性的比较分析

3种鱼中,α-淀粉酶主要分布在幽门盲囊和中肠,其中幽门盲囊α-淀粉酶活性最高(P < 0.05)。3种鱼胃、中肠、后肠中α-淀粉酶活性比较:五条 > 黄条 > 高体(P < 0.05);黄条前肠中α-淀粉酶活性显著高于高体和五条(P < 0.05);高体幽门盲囊中α-淀粉酶活性显著低于黄条和五条(P < 0.05) (图 3)。

图 3 3种鱼各组织α-淀粉酶活性分布及其比较 Fig.3 The distribution and comparative activity of α-amylase in digestive system of three Seriola species
2.4 脂肪酶活性的比较分析

3种鱼各组织中脂肪酶活性均有较高表达水平(图 4),其中,高体后肠脂肪酶活性显著低于其他组织(P < 0.05);黄条幽门盲囊脂肪酶活性显著高于其他组织(P < 0.05),后肠脂肪酶活性最低(P < 0.05);五条幽门盲囊脂肪酶活性和后肠脂肪酶活性显著高于其他组织(P < 0.05)。3种鱼胃、幽门盲囊、前肠、后肠中脂肪酶活性:黄条和五条显著高于高体(P < 0.05);五条肝脏脂肪酶活性显著高于高体和黄条(P < 0.05),中肠脂肪酶活性显著低于后二者(P < 0.05)。

图 4 3种鱼各组织脂肪酶活性分布及其比较 Fig.4 The distribution and comparative activity of lipase in digestive system of three Seriola species
2.5 碱性磷酸酶活性的比较分析

3种鱼中,碱性磷酸酶主要在幽门盲囊中高表达(图 5)。其中,高体和黄条的碱性磷酸酶活性:幽门盲囊 > 前肠 > 中肠 > 后肠 > 肝脏 > 胃(P < 0.05)。胃和中肠中碱性磷酸酶活性:高体组织酶活性显著低于五条和黄条(P < 0.05),幽门盲囊和后肠中碱性磷酸酶活性:高体 < 五条 < 黄条(P < 0.05),前肠中碱性磷酸酶活性:高体 < 黄条 < 五条(P < 0.05),肝脏中碱性磷酸酶活性:黄条 < 高体 < 五条 (P < 0.05)。

图 5 3种鱼各组织碱性磷酸酶活性分布及其比较 Fig.5 The distribution and comparative activity of alkaline phosphatase in digestive system of three Seriola species
2.6 酸性磷酸酶活性的比较分析

图 6所示,高体酸性磷酸酶活性分布:肝脏 > 幽门盲囊 > 胃,均显著高于肠道(P < 0.05),黄条酸性磷酸酶活性:幽门盲囊显著高于其他组织(P < 0.05);五条酸性磷酸酶活性:幽门盲囊 > 胃 > 肝脏 > 前肠 > 后肠 > 中肠(P < 0.05)。幽门盲囊中酸性磷酸酶活性:黄条 > 五条 > 高体(P < 0.05),前肠和中肠中酸性磷酸酶活性:高体组织酶活性显著低于黄条和五条(P < 0.05),后肠中酸性磷酸酶活性:五条组织酶活性显著高于高体和黄条(P < 0.05)。

图 6 3种鱼各组织酸性磷酸酶活性分布及其比较 Fig.6 The distribution and comparative activity of acid phosphatase in digestive system of three Seriola species
3 讨论

本研究比较了3种属鱼类的消化系统5种消化相关酶的活性分布特性,为深入认识属鱼类的消化生理功能提供了依据。

已有研究表明,同一种鱼类不同生长阶段其消化酶活性存在一定差异,养殖环境及饵料与消化酶活性也存在一定关系,一定范围内盐度、温度的变化也是消化酶活力变化的影响因素(陈慕雁等, 2004; 白晓慧等, 2007; 庄平等, 2008; Miegel et al, 2010),同时消化酶活性与其食性关系密切,但即使食性相同的鱼类其酶活性也存在一定的差异,这也是生物本身对环境的一种适应机制(谭北平, 1995)。本研究发现,同一养殖条件同一季节和相同饵料投喂条件下,高体、黄条、五条的5种消化相关酶活性分布特点大致相同,幽门盲囊是5种酶作用的主要靶器官,黄条幽门盲囊酶活性显著高于其他2种鱼,高体酶活性低于黄条和五条。幽门盲囊是鱼类特有的消化器官,其组织学构造与酶含量等都与肠道相似,起着消化和吸收的作用,3种鱼幽门盲囊形态、数量上的差异可能是造成3种鱼消化相关酶活性差异的原因之一,黄条幽门盲囊为120条左右,由少部分长条状幽门盲囊和大部分短条状幽门盲囊组成(李荣等, 2017),高体和五条的幽门盲囊数为60条左右,主要由长条状幽门盲囊组成,黄条幽门盲囊数量是其他2种鱼的2倍左右,大大增加了食物在幽门盲囊停留的时间,有利于食物的消化吸收,消化能力大小既取决于消化酶水平,也取决于运输时间(Fountoulaki et al, 2005),食糜与酶在黄条幽门盲囊接触的时间长于其他2种鱼,故而推测可能是导致酶活性显著高于其他2种鱼的因素之一,但影响鱼类消化相关酶活性因素复杂,具体机制有待进一步深入研究。

3.1 蛋白酶活性分析

食物进入胃后刺激胃酸分泌,胃是胃蛋白酶分泌的最大靶器官(周景祥等, 2000; 章龙珍等; 2016)。通常肉食性鱼类具有较高的蛋白质消化能力,本研究发现,3种鱼胃蛋白酶活性较高且无显著差异,这与乌鳢(Channa argus)、许氏平(Sebastods schlegelii)胃蛋白酶在胃中消化结果一致(郑家声等, 2002; 刘红梅, 2006)。不同部位对蛋白酶的消化能力不同,高体和五条的肝脏是胰蛋白酶的主要作用靶器官,消化能力远高于其他组织,黄条的幽门盲囊是胰蛋白酶的主要作用靶器官,其次才是肝脏,表明3种鱼胰蛋白酶作用的靶器官和代谢机制不同。已有研究表明,有些鱼类的肝胰脏的主要作用是分泌蛋白酶原,肠道分泌肠致活酶,以激活肝脏分泌的蛋白酶原,蛋白酶原经肠液激活后,酶活性明显高于肠道中的蛋白酶活性(倪寿文等, 1993; 李瑾等, 2001; 黄瑾等, 2013)。幽门盲囊也是胰蛋白酶作用的主要器官(黄瑾等, 2013; 付新华等, 2005),黄条幽门盲囊的胰蛋白酶活力显著高于其他2种鱼,可能与黄条幽门盲囊形态及数量远高于其他2种鱼有关,同时这种蛋白酶活性的差异也会因为鱼的种类不同而不同,具体的机制有待于深入研究。

3.2 淀粉酶活性分析

消化道中的淀粉酶主要是消化吸收食物中的碳水化合物和糖类。张正荣等(2020)研究了黄条早期生长过程中淀粉酶活性的变化,发现随着早期生长黄条对碳水化合物的需求逐渐减少。肉食性鱼类淀粉酶活力相比于草食性或杂食性鱼类一般较低,虹鳟(Oncorhynchus mykiss)、大麻哈鱼(Oncorhynchus keta)、大眼鲈(Stizostedion vitreum)、大菱鲆(Scophthalmus maximus)等肉食性鱼类幽门盲囊的淀粉酶活性最高,其次是肠道,肝脏中淀粉酶活性最弱(北御门等, 1960; 周景祥等, 2000; 付新华等, 2005)。本研究中,3种鱼养殖的饵料是玉筋鱼,结果发现幽门盲囊是3种鱼淀粉酶消化的主要靶器官,其次是中肠,食物进入胃中被磨碎后进一步经过幽门盲囊和肠道,在较发达的幽门盲囊中消化和吸收的时间长,淀粉酶的高活性可能表明碳水化合物的消化主要依靠幽门盲囊和中肠。肝脏和胃淀粉酶活力很低,可能是胃液的pH值较低,其酸性环境不利于淀粉酶发挥生理功能(余涛等, 2002),导致胃中的淀粉酶活性较弱。3种鱼均具有较长的胆管,前端与肝脏连接,肝脏主要分泌胆汁从而消化食物中的脂类物质,这与鲟鱼(Acipenser sinensis)肝脏淀粉酶消化活性的特点一致(李瑾等, 2001; 章龙珍等, 2016)。

3.3 脂肪酶活性分析

脂肪酶主要是由鱼类的肝胰脏分泌,在鱼类的消化生理中占据很重要的地位。3种鱼脂肪酶活性在各组织中的分布不存在一致的规律。黄条和五条的幽门盲囊是脂肪酶主要作用的靶器官,其次是肠道,大多数肉食性鱼类的大部分脂质吸收发生在幽门盲囊和肠道(Denstadli et al, 2004),并由胆盐促进,通过激活胆盐依赖的脂肪酶促进其消化吸收(Denton et al, 1974; Iijima et al, 1998)。Mankura等(1984)比较了几种肉食性海水鱼类,发现幽门盲囊脂肪酶活性最高,脂肪酶活性也会与鱼的种类和大小及幽门盲囊的数量有关(宋波澜等, 2007)。属鱼类肌肉的脂肪含量相对较高(柳学周等, 2017),这种高脂肪含量与脂肪酶的活性存在密切的相关关系。

3.4 酸性磷酸酶活性分析

酸性磷酸酶(ACP)是溶酶体的一种标志酶,参与吞噬细胞的胞内消化、核酸和蛋白质、磷酸酯的代谢、免疫调节等重要生命活动(Li et al, 2009)。本研究发现,幽门盲囊是酸性磷酸酶作用的主要靶器官,3种鱼的肠道酸性磷酸酶活性最低。溶酶体的基本功能是对生物大分子的强烈消化作用,以维持细胞的正常代谢活动(翟中和, 1995),食物在消化道中激活溶酶体中的酸性磷酸酶进行胞内消化、核酸、蛋白质、酸磷脂等的代谢,从而维持细胞正常的新陈代谢(魏炜等, 2001),说明酸性磷酸酶主要在鱼的幽门盲囊中发挥胞内消化及酸磷脂代谢等功能,胃和肝脏是酸性磷酸酶作用的次要靶器官,肠道的主要作用是吸收营养。

3.5 碱性磷酸酶活性分析

碱性磷酸酶作为一种吸收酶在鱼类的肠道均有分布,参与脂类、葡萄糖、钙和无机磷等营养物质的吸收和转运(Tengjaroenkul et al, 2000; Cara et al, 2003)。3种鱼碱性磷酸酶活性呈现幽门盲囊、前肠、中肠、后肠、肝脏、胃依次递减的趋势,说明幽门盲囊是碱性磷酸酶主要分布表达的靶器官,该结果与褐牙鲆(Paralichthys olivaceus)、鲟鱼、卵形鲳鲹(Trachinotus ovatus)消化道中碱性磷酸酶的研究结果基本一致(王宏田, 2000; 杨贵强等, 2008; 区又君等, 2011)。王锐等(2001)研究认为,文昌鱼(Branchiostoma belcheri)消化道中的碱性磷酸酶活性与跨膜运输有关,可参加物质的转运。区又君等(2011)研究认为,消化道细胞可通过内吞作用将食物吞入细胞内,借助溶酶体对摄入的营养物质进行消化、吸收和转运,从而完成整个消化过程,因此,幽门盲囊和肠道对营养物质的消化、吸收和转运能力更强,有研究发现,大弹涂鱼(Boleophthalmus pectinirostris)和大鳞大麻哈鱼(Oncorhynchus tschawytscha)的胃上皮细胞对葡萄糖、钙和无机磷的消化吸收能力较强(Kapoor et al, 1975; 吴仁协等, 2007),但由于属鱼类胃的主要作用是储存并分解食物,所以吸收能力可能相对较弱。黄条的幽门盲囊碱性磷酸酶活性显著高于其他组织及其他2种鱼,推测和黄条幽门盲囊较大,且数量是其他2种鱼的2倍有关,食物在黄条幽门盲囊内消化更彻底,对葡萄糖、钙和无机磷的消化吸收能力更强。

本研究比较分析了3种鱼5种消化相关酶活性的组织分布特征,明确了不同鱼种和组织中酶活性的特异性,为专用高效配合饲料研制过程中原料选择、组分配比的技术方案制定提供了依据。在今后鱼专用高效饲料研制过程中,应主要借鉴其不同组织的消化相关酶分布特性,针对性研发不同鱼种特异性的专用配合饲料,促进养殖鱼生长代谢,进而推动我国鱼养殖产业快速持续发展。

参考文献
BAI X H, XIONG C X. Different feed including the type and feed ingredients, different protein source and protein content, feed additives and feed processing had significant effect on the digestive enzymes of fish. China Feed, 2007(10): 20 [白晓慧, 熊传喜. 不同饲料对鱼类消化酶活性的影响. 中国饲料, 2007(10): 20 DOI:10.3969/j.issn.1004-3314.2007.10.009]
CARA J B, MOYANO F J, CARDENAS S, et al. Assessment of digestive enzyme activities during larval development of white bream. Journal of Fish Biology, 2003, 63: 48-58 DOI:10.1046/j.1095-8649.2003.00120.x
CHEN M Y, ZHANG X M. Recent advances in digestive physiology of marine fish larvae-juvenile. Progress in Fishery Sciences, 2004, 25(3): 81-88 [陈慕雁, 张秀梅. 海水鱼类仔稚鱼消化生理学研究进展. 渔业科学进展, 2004, 25(3): 81-88 DOI:10.3969/j.issn.1000-7075.2004.03.014]
DENSTADLI V, VEGUSDAL A, KROGDAHL A, et al. Lipid absorption in different segments of the gastrointestinal tract of Atlantic salmon (Salmo salar L.). Aquaculture, 2004, 240: 385-398 DOI:10.1016/j.aquaculture.2004.06.030
DENTON J, YOUSEF I, KUKSIS A. Bile acid composition of rainbow trout, Salmo gairdneri. Lipids, 1974, 9: 945-951 DOI:10.1007/BF02533816
FOUNTOULAKI E, ALEXIS M N, NENGAS I, et al. Effect of diet composition on nutrient digestibility and digestive enzyme levels of gilthead sea bream (Sparus aurata L.). Aquaculture Research, 2005, 36: 1243-1251 DOI:10.1111/j.1365-2109.2005.01232.x
FU X H, SUN M, SUN S C. Activity of digestive enzymes in Scophthalmus maximus. Journal of Fishery Sciences of China, 2005, 12(1): 26-32 [付新华, 孙谧, 孙世春. 大菱鲆消化酶的活力. 中国水产科学, 2005, 12(1): 26-32 DOI:10.3321/j.issn:1005-8737.2005.01.006]
HUANG J, XIONG B X, CHEN J, et al. Activity and distribution of digestigestive enzymes for paddlefish (Polyodon spathula). Journal of Huazhong Agricultural University, 2013, 32(1): 110-115 [黄瑾, 熊邦喜, 陈洁, 等. 匙吻鲟的消化酶分布及其活性. 华中农业大学学报, 2013, 32(1): 110-115 DOI:10.3969/j.issn.1000-2421.2013.01.021]
IIJIMA N, TANAKA S, OTA Y. Purification and characterization of bile salt-activated lipase from the hepatopancreas of red sea bream, Pagrus major. Fish Physiology and Biochemistry, 1998, 18: 59-69 DOI:10.1023/A:1007725513389
KAPOOR B G, SMITH H, VERIGHINA I A. The alimentary canal and digestion in teleosts. Advances in Marine Biology, 1975, 13: 109-239
KOFUJI P Y M, AKIMOTO A, HOSOKAWA H, et al. Seasonal changes in proteolytic enzymes of yellowtail Seriola quinqueradiata (Temminck & Schlegel; Carangidae) fed extruded diets containing different protein and energy levels. Aquaculture and Fisheries Management, 2005, 36(7): 696-703
LI J Y, SUN X Q, ZHENG F R, et al. Histochemical localization and characterization of AKP, ACP, NSE, and POD from cultured Apostichopus japonicus. Chinese Journal of Oceanology and Limnology, 2009, 27(3): 550-554 DOI:10.1007/s00343-009-9125-z
LI J, HE R G, WANG X D. Comparative studies on digestive enzymatic activities of the four alimentary organs in Acipenser sinensis. Fisheries Science Technology Information, 2001(3): 99-102 [李瑾, 何瑞国, 王学东. 中华鲟消化酶活性分布的研究. 水产科技情报, 2001(3): 99-102 DOI:10.3969/j.issn.1001-1994.2001.03.010]
LI R, XU Y J, LIU X Z, et al. Morphometric analysis and internal anatomy of yellowtail kingfish (Seriola aureovittata). Progress in Fishery Sciences, 2017, 38(1): 142-149 [李荣, 徐永江, 柳学周, 等. 黄条(Seriola aureovittata)形态度量与内部结构特征. 渔业科学进展, 2017, 38(1): 142-149]
LIU H M. Study on the histology and enzyme in the digestive tract of Ophicephalus argus. Master′s Thesis of Ocean University of China, 2006, 28-29 [刘红梅. 乌鳢消化系统组织学及消化酶的研究. 中国海洋大学硕士研究生学位论文, 2006, 28-29]
LIU W, CHEN Q H, TANG F J, et al. Comparison of activities of digestive enzymes among four culter species in Xingkai Lake. Chinese Journal of Fisheries, 2017, 30(5): 23-27 [刘伟, 陈清华, 唐富江, 等. 兴凯湖四种野生鲌消化酶活性比较研究. 水产学杂志, 2017, 30(5): 23-27 DOI:10.3969/j.issn.1005-3832.2017.05.005]
LIU X Z, XU Y J, LI R, et al. Analysis and evaluation of nutritional composition of the muscle of yellowtail kingfish (Seriola aureovittata). Progress in Fishery Sciences, 2017, 38(1): 128-135 [柳学周, 徐永江, 李荣, 等. 黄条 (Seriola aureovittata)肌肉营养组成分析与评价. 渔业科学进展, 2017, 38(1): 128-135]
MANKURA M, KAYAMA M, SAITO S. Wax ester hydrolysis by lipolytic enzymes in pyloric ceca of various fishes. Bulletin of the Japanese Society of Scientific Fisheries, 1984, 50(12): 2127-2131 DOI:10.2331/suisan.50.2127
MIEGEL R P, PAIN S J, VAN WETTERE W H E J, et al. Effect of water temperature on gut transit time, digestive enzyme activity and nutrient digestibility in yellowtail kingfish (Seriola lalandi). Aquaculture, 2010, 308(3/4): 145-151
NI S W, GUI M Y, LIU H L. Investigation on the comparison of protease activities in grass carp, common carp, silver carp, big head carp and tilapla nilotica. Acta Zoologica Sinica, 1993, 39(2): 160-168 [倪寿文, 桂明远, 刘焕亮. 草鱼、鲤、鲢、鳙和尼罗非鱼肝胰脏和肠道蛋白酶活性的初步探讨. 动物学报, 1993, 39(2): 160-168 DOI:10.3321/j.issn:0001-7302.1993.02.015]
NORTY M, LEARN W S. Digestive enzymes study. Journal of Japan´ s Fisheries Society, 1960, 26(7): 685-690 [北御门, 学野新光. 消化酶素研究. 日本水产学会志, 1960, 26(7): 685-690]
OU Y J, LUO Q, LI J E. Distribution and cryopreservation of alkaline phosphatase (AKP) and acid phosphatase (ACP) in Trachinotus ovatus. South China Fisheries Science, 2011, 7(2): 49-54 [区又君, 罗奇, 李加儿. 卵形鲳鲹碱性磷酸酶和酸性磷酸酶的分布及其低温保存. 南方水产科学, 2011, 7(2): 49-54 DOI:10.3969/j.issn.2095-0780.2011.02.008]
SONG B L, CHEN G, YE F L, et al. Relation between lipase activities and environmental factors in the young fish of Rachycentron canadum. Journal of Jinan University (Natural Science), 2007, 8(5): 531-536 [宋波澜, 陈刚, 叶富良, 等. 军曹鱼幼鱼脂肪酶的活力与环境因子的关系. 暨南大学学报(自然科学版), 2007, 8(5): 531-536]
TAN B P. Studies on protease activity of some predatory fishes in coastal area of Taihu Lake. Journal of Hubei Agricultural College, 1995, 15(2): 96-98 [谭北平. 太湖沿岸区几种肉食性鱼类蛋白酶活性的研究. 湖北农学院学报, 1995, 15(2): 96-98]
TENGJAROENKUL B, SMITH B J, CACECI T, et al. Distribution of intestinal enzyme activities along the intestinal tract of cultured Nile tilapia, Oreochromis niloticus L. Aquaculture, 2000, 182: 317-327 DOI:10.1016/S0044-8486(99)00270-7
WANG B, SUN P X, DONG Z F. Biological characteristics and aquaculture of yellowtail kingfish (Seriola lalandi). Fishery Modernization, 2005(3): 18-20 [王波, 孙丕喜, 董振芳. 黄尾的生物学特性与养殖. 渔业现代化, 2005(3): 18-20 DOI:10.3969/j.issn.1007-9580.2005.03.007]
WANG H T. The research on immune system and disease resistance of flounder, Paralichthys olivaceus. Doctoral Dissertation of Institution Oceanology, Chinese Academy of Sciences, 2000, 70-80 [王宏田. 牙鲆免疫系统和抗病力的研究. 中国科学院海洋研究所博士研究生学位论文, 2000, 70-80]
WANG R, ZHANG S C. Distribution of alkline phosphatase in amphioxus Branchiostoma belcheri tsingtaunese. Journal of Ocean University of Qingdao, 2001, 31(1): 81-85 [王锐, 张士璀. 碱性磷酸酶在文昌鱼体内的分布. 青岛海洋大学学报, 2001, 31(1): 81-85]
WEI W, ZHANG H Y, SHI A J. The study of relationship between acid phosphatase activity and oyster defence. Acta Hydrobiologica Sinica, 2001, 25(4): 413-415 [魏炜, 张洪渊, 石安静. 育珠蚌酸性磷酸酶活力与免疫反应关系的研究. 水生生物学报, 2001, 25(4): 413-415]
WU R X, GE W, HONG W S, et al. Digestive enzymes of adult mudskipper Boleophthalmus pectinirostris. Journal of Fishery Sciences of China, 2007, 14(1): 99-105 [吴仁协, 戈薇, 洪万树, 等. 大弹涂鱼成鱼消化酶活性的研究. 中国水产科学, 2007, 14(1): 99-105]
YANG G Q, ZHANG Y, WANG N M, et al. Comparison on activities of phosphatase and alexin in the serum and tissue of three kinds of sturgeons. Journal of Fisheries Science, 2008, 21(1): 53-58 [杨贵强, 张颖, 王念民, 等. 三种鲟鱼血清及组织中磷酸酶和补体活性的比较. 水产学杂志, 2008, 21(1): 53-58]
YU T, SHI L C, QU D F, et al. Activities of digestive enzyme in Pseudobagrus fulvidraco. Journal of Jilin Agricultural University, 2002, 24(5): 92-94 [余涛, 施立才, 曲东风, 等. 黄颡鱼消化酶活性的初步研究. 吉林农业大学学报, 2002, 24(5): 92-94]
ZHANG L Z, CHEN N N, ZHANG T, et al. The activity and distribution of digestive enzymes in 2-year-old Acipenser baerii. Marine Fisheries, 2016, 38(2): 166-173 [章龙珍, 陈宁宁, 张涛, 等. 2龄西伯利亚鲟消化酶活性分布. 海洋渔业, 2016, 38(2): 166-173]
ZHANG Z R, LIU X Z, YU Y, et al. The variations of digestive enzymes in larval and juvenile Seriola aureovittata. Progress in Fishery Sciences, 2020, 41(2): 61-68 [张正荣, 柳学周, 于毅, 等. 黄条仔稚幼鱼消化酶活性变化研究. 渔业科学进展, 2020, 41(2): 61-68]
ZHENG J S, FENG X Y. Distribution of intestinal enzymes in digestive tract of tract of Sebastes schlegeli. Journal of Fishery Sciences of China, 2002, 9(4): 309-314 [郑家声, 冯晓燕. 许氏平. 中国水产科学, 2002, 9(4): 309-314]
ZHOU J X, ZHANG D M, HUANG Q, et al. Studies on the activities of amylase of walleye (Stizosedion vitreum). Journal of Jilin Agricultural University, 2000, 22(3): 107-110 [周景祥, 张东鸣, 黄权, 等. 大眼鲈蛋白酶活性的研究. 吉林农业大学学报, 2000, 22(3): 107-110]
ZHUANG P, ZHANG L Z, TIAN H J, et al. Effects of salinity on digestive enzyme activities of juvenile Acipenser schrenckii. Journal of Fishery Sciences of China, 2008, 2: 198-203 [庄平, 章龙珍, 田宏杰, 等. 盐度对施氏鲟幼鱼消化酶活力的影响. 中国水产科学, 2008, 2: 198-203]