不同发育时期月鳢消化酶活性的变化

对月鳢稚鱼、幼鱼和成鱼的主要消化酶活性及分布进行了研究,结果如下：①随着鱼体发育和生长,月鳢消化系统各器官组织的各种消化酶活性不断地增强,尤其是蛋白酶和脂肪酶活性的发育更为明显。②月鳢幼鱼蛋白酶活性以肠组织最大,肝胰脏次之,胃组织最小,且肠组织和肝胰脏中该酶活性显著高于胃组织;胰蛋白酶活性以肝胰脏最大,胃组织和肠组织均表现较小;淀粉酶活性和脂肪酶活性均以胃组织最大,且显著大于肠组织和肝胰脏。③月鳢成鱼蛋白酶活性以中肠粘膜组织和后肠粘膜组织最高,前肠粘膜和肝胰脏次之,胃粘膜最低;胰蛋白酶活性以中肠粘膜组织和前肠粘膜最高,胃粘膜组织次之,肝胰脏小于胃粘膜,后肠粘膜组织的胰蛋白酶活性最小;淀粉酶活性以后肠粘膜组织和中肠粘膜组织最大,肝胰脏次之,胃粘膜组织和前肠粘膜组织最小;脂肪酶活性以胃粘膜组织最大,其他器官组织该酶活性均表现较小。     

光照强度对紫海胆浮游幼体生长及消化酶活性的影响

本研究以紫海胆(Anthocidaris crassispina)为研究对象,通过水槽实验方法,模拟分析了自然光周期条件下光照强度对紫海胆浮游幼体生长、存活以及体内消化酶活性的影响,旨在为紫海胆苗种的规模化繁育提供必要的生物学参数。研究发现,在实验设计的光照强度梯度(0、500、1000、2000、3000 lx)内,光照强度对紫海胆浮游幼体的体长、躯干部骨针长度和口后腕骨针长度的影响趋势一致,影响程度由高到低为500 lx>0 lx>1000 lx>2000 lx>3000 lx。在500 lx条件下,紫海胆浮游幼体的体长、躯干部骨针长度和口后腕骨针长度都达到最高,且显著优于其他实验组(P<0.05),此时脂肪酶和淀粉酶活性最强;在2000 lx条件下,紫海胆的胃蛋白酶活性最强;在3000 lx条件下,紫海胆浮游幼体发育到11 d已全部死亡。研究表明,在500 lx光照强度下,紫海胆浮游幼体可保持最佳的生长速度、消化酶活性以及存活率,500 lx为紫海胆浮游幼体生长发育的最佳光照强度。     

狼鳗的外部形态、消化系统和生殖系统的观察

采用观察、测量、解剖和拍照的方法,对狼鳗(Anarrhichthys ocellatus)的外部形态、可数可量性状及消化系统、生殖系统进行研究,并描述了狼鳗的相关特征。结果显示,狼鳗体型为鳗形,整体呈黑色或灰黑色,头部、背部及背鳍鳍条上有若干似眼睛的黑色圆斑,体表无鳞。背鳍鳍条数为232~267,胸鳍鳍条数为15~22,臀鳍鳍条数为189~220,无腹鳍,背鳍和臀鳍因与尾鳍相连而无明显区分界限,侧线左右各2条,均不完整,雄性侧线点明显,而雌性侧线点不明显。上排侧线点数为18~25,下排侧线点数为76~85。上鳃耙数为49~70,下鳃耙数为55~73,脊椎骨数为232~271。全长/体长线性相关性最好,雌、雄差异很小,稳定性最好。头长/吻长、头长/眼径、体长/肠长的变化范围较大,雌、雄间差异较大,线性相关性差,可以作为区分狼鳗雌、雄的重要特征;狼鳗体重与体长关系:W=0.0337S12.4798(R²=0.9992),雌性:W=0.0326Si2.4864(R²=0.9990),雄性:W=0.0359Si2.4672(R²=0.9995)。消化系统由消化道和消化腺构成,口咽腔大,具颌齿,无腭齿、犁齿,咽喉齿发达;胃大,呈"Ⅰ"型,无幽门盲囊;肠短粗,比肠长为0.45;相关性状及特征显示狼鳗为肉食性鱼类。雌雄异体,卵巢(Ⅲ~Ⅳ)呈椭圆形,粉红色,左右对称,精巢(Ⅲ~Ⅳ)呈黄白色,"Y"形。     

不同糖源对卵形鲳鲹(Trachinotus ovatus)日增重、饲料利用和消化酶活性的影响

以葡萄糖、蔗糖、糊精、玉米淀粉和糊化玉米淀粉为糖源制成5种等氮等脂饲料,投喂卵形鲳碜(Trachinotus ovatus)8周,研究不同糖源对其日增重、饲料利用和肝脏消化酶活性的影响.结果显示,不同糖源对卵形鲳鲹日增重、饲料效率和蛋白效率均有显著影响(P＜0.05).糊化玉米淀粉组的日增重、饲料效率和蛋白效率均最高,显著高于非淀粉糖源组(P＜0.05),而与玉米淀粉组无显著差异(P＞0.05);葡萄糖组的日增重、饲料效率和蛋白效率均最低,显著低于其他糖源组(P＜0.05).消化酶活性结果显示,饲料中的不同糖源对卵形鲳鲹的肝脏消化酶活性有显著影响(P＜0.05).两个淀粉组的蛋白酶活性显著低于分子量较低其他三组(P＜0.05);蔗糖组的淀粉酶活性最高,显著高于除糊精组外的其他糖源组(P＜0.05);脂肪酶活性随着糖分子量的增大而增大.本研究中淀粉类大分子糖类对卵形鲳鲹的促生长效果优于葡萄糖、蔗糖和糊精,糊化玉米淀粉组的促生长效果最好.     

宽口裂腹鱼消化系统解剖和组织学观察

该研究采用解剖、石蜡切片和HE染色法对宽口裂腹鱼(Schizothorax eurystomus)消化系统解剖特征和组织切片进行观察。结果显示,其消化管管壁由内向外分别为黏膜层、黏膜下层、肌层和浆膜,主要差别在于黏膜层和肌层。食道黏膜上皮为复层扁平上皮,上皮间分布有大量杯状细胞;前肠和中肠黏膜上皮为单层柱状上皮,明显可见刷状缘、杯状细胞和淋巴细胞分布其间;后肠黏膜上皮为假复层柱状上皮,其间也有杯状细胞和淋巴细胞分布,肠道中杯状细胞由前至后逐渐增多。食道肌层为内环外纵的骨骼肌;前肠肌层为内环外纵的平滑肌;中肠和后肠为内螺旋外环行的平滑肌。消化腺由肝脏和胰腺组成,胰腺弥散状分布在肝脏中,肝小叶不明显。研究表明,宽口裂腹鱼消化系统组织学特征与其食性具有适应性。     

大黄鱼消化道菌群结构、消化酶和非特异性免疫酶活力分析

为研究大黄鱼(Larimichthys crocea)消化道的菌群结构、消化酶和非特异性免疫酶活力特征,本研究采用高通量测序技术系统分析大黄鱼胃、幽门盲囊和肠道中菌群组成及分布,并对比研究工厂化养殖和网箱养殖模式下的消化道菌群;同时,结合生化分析方法解析2种模式下消化道消化酶和非特异性免疫酶活力特征。结果显示,2种养殖模式下,菌群多样性随消化道延伸呈下降趋势;乳杆菌科(Lactobacillaceae(f))、Fructobacillus、黄杆菌属(Flavobacterium)等代表的菌属为共有优势菌群。其中,拟杆菌属(Bacteroides)和Anaerostipes等的丰度随消化道延伸呈下降趋势,而乳杆菌科、E01_9C_26_marine_group(o)所代表的菌属及黄杆菌属等则相反;普氏菌属(Prevotella_9)、乳杆菌科代表的菌属为2种模式养殖大黄鱼的主要差异菌属。工厂化养殖条件下,幽门盲囊和肠道中的菌群组成及其参与营养和免疫相关代谢通路的基因数目差异不显著(P>0.05),但与胃部的菌群组成和相关代谢通路基因数目存在明显差异;而网箱养殖大黄鱼胃部与幽门盲囊和肠道的菌群结构及相关代谢通路基因数目差异相对较小。2种养殖模式下的大黄鱼消化道菌群与饲料菌群相近。另外,胃和幽门盲囊也具有非特异性免疫酶活性,说明,整个消化道还具有一定的化学免疫屏障作用。本研究结果将为大黄鱼健康养殖提供基础参考,并为消化道菌群生理功能探讨提供理论依据。     

黄条鰤仔稚幼鱼消化酶活性变化研究

为了解黄条鰤(Seriola aureovittata)早期发育阶段的消化生理特性,测定了黄条鰤胚胎、仔稚幼鱼阶段脂肪酶、淀粉酶、胰蛋白酶和碱性磷酸酶活性变化。结果显示,在黄条鰤仔鱼出膜前胚胎阶段,即能检测到脂肪酶、淀粉酶和碱性磷酸酶活性;初孵仔鱼体内(1 d)初次检测出胰蛋白酶的活性。脂肪酶和碱性磷酸酶比活力在仔鱼孵化后迅速增强(P<0.05),在4 d开口时,2种酶比活力达最高值;淀粉酶比活力在7 d时达最大值;胰蛋白酶比活力在仔鱼阶段缓慢上升,15 d时比活力最大。稚鱼阶段内脏团中脂肪酶、碱性磷酸酶和胰蛋白酶活性基本维持稳定,幼鱼阶段内脏团脂肪酶、碱性磷酸酶和胰蛋白酶活性都呈现上升趋势;稚鱼和幼鱼阶段内脏团中淀粉酶活性下降并基本稳定于较低水平。研究表明,黄条鰤仔稚幼鱼发育过程中,各种消化酶活性变化明显,且与其发育阶段和食性密切相关。在尚未摄食饵料的早期仔鱼体内已存在消化酶,认为其是母源传递而来,不是由外源性饵料所致;幼鱼阶段内脏团脂肪酶、碱性磷酸酶和胰蛋白酶比活力明显提高,这反映出随苗种生长发育,其肠道结构和消化机能逐渐完善,并且对脂肪、蛋白质的需求逐渐增强。     

栉孔扇贝消化盲囊亚细胞组分分离与鉴定技术

采用匀浆、差速离心、镜检和标志酶测定等方法,研究了栉孔扇贝(Chlamys farreri)消化盲囊亚细胞组分分离与鉴定技术。结果显示,经Hoechst33258染色,在匀浆2min对照组中,观察到大量栉孔扇贝消化盲囊完整细胞,呈圆形或椭圆形,细胞膜完整,荧光强度较高;在匀浆3、4、5 min实验组中,完整细胞数目逐渐减少,且出现许多形态较小、荧光强度弱、轮廓模糊的细胞碎片。通过血球计数板法得到的细胞破碎结果与上述染色结果一致,随着匀浆时间(2~5 min)的增加,细胞破碎率升高,当匀浆时间达到5 min时,细胞破碎率升至94.24%。利用Hoechst 33258染色栉孔扇贝消化盲囊亚细胞分离组分(S2、C2、C4、S5和C5),镜检发现,C2组分荧光强度最强,荧光颗粒数目多,而其他组分荧光强度弱,且基本观察不到荧光颗粒。由此推测,细胞核主要存在于C2组分中;同时,细胞膜(5’-核苷酸酶)、线粒体(琥珀酸脱氢酶)、细胞质(乳酸脱氢酶)和微粒体(葡萄糖-6-磷酸酶)标志酶活力在其他亚细胞组分中有少量检出,但它们在S2、C4、S5和C5组分中的的标志酶活性比例较高(分别为63.90%、64.89%、77.82%和67.55%)。由此推测,S2、C2、C4、S5和C5分离组分分别为细胞膜、细胞核、细胞质、线粒体和微粒体。本研究成功构建了栉孔扇贝消化盲囊亚细胞组分分离与鉴定技术方法,为贝类生理机制研究提供技术支持。     

The changes in digestive enzymes and hormones of gilthead seabream larvae (Sparus aurata, L 1758) fed on Artemia nauplii enriched with free methionine

Variations in digestive enzymes and hormones during the larval development of gilthead seabream (Sparus aurata) fed on live prey (Artemia nauplii) enriched with free methionine were investigated for 16 days (from day 24 to day 40). Prior to initiation of the experiment, newly hatched larvae were transferred from incubators to fiber glass tanks (300 l) with black walls and fed with same diets until day 24. Each experiment was performed in triplicate. In the experimental group, the content of the free methionine in the Artemia nauplii was increased by adding a 5.3 mM free methionine solution to the culture water during a 16-h enrichment period. The larvae of both the control and enriched-methionine groups were sampled four times, with 4-day intervals between samplings, during a 16-day period. The larvae in the control group had a significantly lower growth than those of the methionine group at the end of the study (P < 0.05). The highest trypsin activity and leucine aminopeptidase N/leucine–alanine peptidase ratios were observed in the control group. A significant difference between bombesin activities in the treatment groups was not found at 5th minute after the initiation of feeding (P > 0.05), but they were significant at 15th minute post-initiation of feeding (P < 0.05). A significant difference between the cholecystokinin levels of the treatment groups was found (P < 0.05).     

Effects of dietary medicinal herbs and Bacillus on survival, growth, body composition, and digestive enzyme activity of the white shrimp Litopenaeus vannamei

The basal diet (C), with 0.20% medicinal herbs (M) and 0.30% Bacillus (BM1), with 0.10% medicinal herbs and 0.15% Bacillus (BM2), and with 0.30% Bacillus (B), was used to feed white shrimps (Litopenaeus vannamei) (1.91 ± 0.03 g) in order to assess survival, growth, body composition, and digestive enzyme activity. At the end of the feeding trial, survival ranged from 95.83 to 98.33% with no significant difference (P > 0.05) among all groups. Growth measured as weight gain was significantly (P < 0.05) higher in shrimp fed with BM2, BM1, and M compared to that of C. However, no significant differences were found among B, BM1, and M. In the case of specific growth rate, the shrimp fed with BM1 and BM2 exhibited significantly (P < 0.05) higher values than that of C. The contents of body moisture, crude protein, and ash seemed to be unaffected by the feed supplements, though lipid content was found to be significantly (P < 0.05) different among the treatments. The shrimp fed with BM1 and BM2 had the lowest and highest lipid contents, respectively. The digestive enzyme activity assessed using shrimp hepatopancreas revealed that the activities of amylase and protease in shrimp fed with BM2 were significantly (P < 0.05) higher than those of C at the end of the 2nd and 6th weeks. However, better performance of the specific amylase activity was shown by the shrimp fed with B at the end of the 8th week.