异育银鲫口服不同剂量淀粉后血糖和血脂代谢变化

碳水化合物是鱼类饲料中易得且价廉的非蛋白能源,可以节约蛋白质分解供能,但大多数鱼类对糖的耐受量很低,表现出一种类似糖尿病的症状。反映鱼类的血糖调节能力的首要指标是糖耐量实验,Wilson早在1994年就通过灌喂方式进行糖耐量实验来研究鱼类对糖的耐受情况。鱼类对糖的利用能力因鱼的种类不同而不同。在糖耐量实验中,对于肉食性的鱼类,需要在饲料中给予较低水平的碳水化合物才会产生一个基础血糖水平,如果没有对这种含碳水化合物的饲料进行适应,它们对血糖的调节能力极为低下。杂食性鱼类对葡萄糖的耐受量要比肉食性鱼类高。     

乙肝病毒X蛋白结合蛋白通过下调PEPCK的表达抑制肝脏糖异生

乙肝病毒X蛋白结合蛋白（hepatitis B X-interacting protein,HBXIP）可以调节乳腺癌中糖代谢重编程. 为了研究HBXIP在生理条件下对糖代谢的调节作用及机制,本研究利用Cre/loxP重组酶系统成功构建了肝脏组织中HBXIP特异敲除小鼠. 当小鼠接受刺激后,与正常组小鼠相比,肝脏HBXIP敲除小鼠表现基础糖代谢功能异常,如葡萄糖、丙酮酸;相对于对照小鼠,肝脏HBXIP敲除小鼠对糖异生和胰岛素耐受性减弱. RT-PCR、Western blot实验和免疫组化实验结果表明,HBXIP敲除小鼠肝脏组织中糖异生关键酶磷酸烯醇式丙酮酸羧化酶(phosphoenolpyruvate carboxykinase,PEPCK)表达显著增加. QRT-PCR 分析30例临床肝组织中HBXIP mRNA和PEPCK mRNA表达水平发现,HBXIP与PEPCK表达水平呈负相关. 荧光素酶报告基因实验和ChIP实验结果表明HBXIP可以在基因转录水平调节PEPCK表达. 以上结果表明,HBXIP通过调节糖异生关键酶PEPCK的表达参与调控小鼠肝脏糖异生.     

乌鱼—很好的养殖对象

鸟鱼 Ophicephalus argus(Cantor)是一种凶猛的肉食性鱼类,是养鱼业之害。因此,在养鱼池中进行除野,清除鸟鱼和其他肉食性鱼类的危害是必要的。但是,鸟鱼也是有着很大养殖价值的鱼类,可以成力很好的养殖对象之一。1.鸟鱼的生长速度很快,这是决定一种鱼有无养殖价值的主要标志。根据我们对邛海鸟鱼生长的研究,发现有的鸟鱼仅一年多的时间体长就达到48厘米,体重达到1343克。曾得到一条长71.5厘米,重     

不同糖源及糖水平对大菱鲆糖代谢酶活性的影响

采用34双因素实验设计, 以初始质量为(8.060.08) g的大菱鲆幼鱼(Scophthalmus maximus L.)为对象, 研究在饲料中添加3种糖源(葡萄糖、蔗糖和糊精)及4个水平(0、5%、15%、28%)对大菱鲆肝脏糖酵解关键酶己糖激酶(HK)、葡萄糖激酶(GK)、磷酸果糖激酶(PFK)、丙酮酸激酶(PK)和糖异生关键酶磷酸烯醇式丙酮酸羧激酶(PEPCK)、1, 6-二磷酸果糖酶(FBPase)活性的影响。结果表明: 饲料糖添加量从0升高到15%时, 大菱鲆的糖酵解酶GK和PK活性随饲料葡萄糖或糊精含量的增加而增加; 当饲料中葡萄糖或糊精含量为28%时, GK和PK活性有下降的趋势。3种糖源的4个添加水平对HK和PFK活性均无显著影响(P 0.05)。添加不同水平的葡萄糖对大菱鲆糖异生途径的PEPCK活性无显著影响(P 0.05), 但在饲料中葡萄糖添加量为5%时显著促进了FBPase活性(P 0.05), 当葡萄糖添加量升高为15%或28%时, FBPase活性与对照组无显著差异(P 0.05)。糊精作为饲料糖源时抑制了大菱鲆肝脏FBPase和PEPCK的活性, 而添加不同水平的蔗糖对FBPase和PEPCK活性的影响均不显著(P 0.05)。总的来说, 从大菱鲆幼鱼肝脏糖代谢角度而言, 在饲料中添加15%的葡萄糖或糊精时, 可以有效促进大菱鲆肝脏糖酵解能力; 较添加葡萄糖, 糊精在促进大菱鲆肝脏糖酵解的同时对糖异生存在一定程度的抑制。蔗糖作为饲料糖源时, 仅在添加量为28%时显著促进糖酵解酶GK活性, 糖酵解其他酶活性以及糖异生酶活性均不受蔗糖水平的显著影响。       

军曹鱼营养需求与饲料研究进展

目前, 养殖鱼类已成为满足人类对水产品需求的主要来源。军曹鱼(Rachycentron canadum)具有生长速度快、肉质细嫩鲜美、营养价值高等特点, 已成为我国南方重要的海水网箱养殖鱼类。然而, 目前饲养军曹鱼仍主要依靠冰鲜杂鱼, 特别是大规格鱼的养殖, 这严重制约其养殖业的健康发展, 研发适合不同生长阶段需要的配合饲料非常必要。文章重点总结了军曹鱼对蛋白质、脂肪、氨基酸、脂肪酸、微量营养素等的需求, 饲料中鱼粉和鱼油替代研究, 饲料添加剂应用及其饲料产业发展现状, 以期为军曹鱼营养需求和配合饲料开发的深入研究提供参考。     

我国东北的狗鱼

在松花江和黑龙江上的渔家,根据狗鱼的头部和嘴的形状,又长、又扁、又薄而又坚硬,叫它为鸭子鱼.因为食性贪婪,牙齿尖锐,所以又叫它为狗鱼.在解放前,我国研究鱼类的文献中,还没有系统地介绍过这种鱼,解放后,东北人民出版社编印的中学动物学教科书上,曾有一幅狗鱼的图片;在课文中的鱼类部分,提到狗鱼是一种凶猛性的鱼类.最近经过修订的这个教本,把凶猛性的鱼,改用了,在我国分布得比较广泛的乌鳢(Ophiocephalus orgus).那一幅图片也取消了.因此,引起了对鱼类有兴趣的人们提出了这些问题:我国出产狗鱼么?     

3种不同食性淡水鱼类谷胱甘肽S-转移酶Pi、Mu、Theta型cDNA序列的克隆分析及表达

鱼类谷胱甘肽S-转移酶(glutathione S-transferase,GST)是鱼类一种重要的Ⅱ相去毒酶,在催化毒素与还原谷胱甘肽(GSH)加合去毒代谢过程中具有关键作用。采用RT-PCR及RACE法,分离、克隆得到草鱼、尼罗罗非鱼pi、mu、theta型GST(GSTpi、GSTmu、GSTtheta)基因、鲢鱼GSTmu、GSTtheta基因的cDNA部分序列并推测各自对应的氨基酸序列。氨基酸序列同源性比较和系统进化分析均表明,鲢鱼、草鱼、尼罗罗非鱼与鱼类GST同源性较高,与哺乳类、鸟类、两栖类GST同源性较低,可能与鱼类GST基因在水环境毒素去毒代谢中承担的特殊功能有关。而不同种鱼类GSTtheta的同源性明显要较GSTpi、GSTmu的同源性低,可能与不同淡水鱼类食性及对毒素耐受性不同有关。用实时荧光定量PCR(RT-PCR)检测三种鱼肝脏中三型GST基因组成型表达水平,发现三种鱼各型之间皆有一定差异,尼罗罗非鱼肝脏整体GSTs基因表达很低,GSTtheta显著低于草鱼(P<0.05),GSTmu显著低于鲢鱼(P<0.05)。本研究为从分子水平上研究不同型谷胱甘肽S-转移酶基因在不同食性淡水鱼类体内代谢去毒过程中的作用提供了基础。     

THE EFFECTS OF VALINE LEVEL ON PLASMA BIOCHEMICAL INDEXES,LIPID CONTENT AND GENE EXPRESSION INVOLVED IN LIPID METABOLISM IN COBIA (RACHYCENTRONCANADUM)

实验旨在研究饲料缬氨酸水平对军曹鱼(Rachycentron canadum)[初始体质量为(40.90.8) g]鱼体脂肪含量、血浆生化指标和肝脏脂肪代谢基因表达的影响。在基础饲料中梯度添加晶体缬氨酸, 配制出缬氨酸含量分别为1.26% (缺乏组)、2.21% (适量组)和2.62% (过量组)3种等氮等脂饲料, 饲喂养殖在海水浮式网箱的军曹鱼10周, 每天饱食投喂2次。结果表明, 缬氨酸缺乏组的军曹鱼鱼体和肌肉脂肪含量显著低于缬氨酸适量组和过量组(P0.05)。肝脏脂肪含量随着饲料中缬氨酸含量从1.26%升高到2.21%而显著升高(P0.05), 然后随之而逐渐下降(P0.05)。军曹鱼血浆总蛋白和总胆固醇含量在缬氨酸缺乏饲料组显著低于其他各处理组(P0.05)。饲料缬氨酸水平对军曹鱼血浆谷草转氨酶和谷丙转氨酶均无显著影响(P0.05)。军曹鱼肝脏固醇调节元件结合蛋白-1 (sterol regulatory element binding protein-1, SREBP-1)基因表达水平和肝脏脂肪酸合成酶(FAS)表达量, 均随着饲料缬氨酸水平增加而显著升高(P0.05)。军曹鱼肝脏过氧化物酶体增殖物激活受体(peroxisome proliferator activated receptor, PPAR)表达量在缬氨酸适量组, 显著低于过量组(P0.05), 而与缺乏组差异不显著(P0.05)。而随着缬氨酸含量升高, 肉毒碱棕榈酰转移酶-1 (CPT-1, Carnitine palmitoyltransferase-1)表达量逐渐下降(P0.05)。总之, 饲料缺乏缬氨酸可减少军曹鱼鱼体脂肪积累。饲料中缬氨酸水平对军曹鱼鱼体脂肪沉积的影响, 可能是通过调控脂肪合成和-氧化相关基因表达而实现的。     

长江宜宾江段铜鱼属鱼类种间食物关系

采用碳、氮稳定同位素技术对2012年4-5月长江宜宾江段铜鱼和圆口铜鱼的食物组成进行了分析,并利用多元统计分析方法探讨了铜鱼和圆口铜鱼种间食物关系,包括饵料相似性指数、重叠系数及2种鱼的摄食器官形态差异对食物组成的影响.结果表明:1)铜鱼的δ13C和δ15N变化范围分别为-21.15‰～-20.31‰和9.67‰～ 10.21‰,为偏动物性的杂食性鱼类;圆口铜鱼的δ13C和δ15N分别为-23.30‰～-21.18‰和7.40‰～ 9.21‰,相对铜鱼为偏植物性的杂食性鱼类,铜鱼和圆口铜鱼均与传统肠含物分析的结果存在一定的差异;2)两种鱼的食物相似性指数和食物重叠系数分别为78.7％和55.6％;3)主成分分析(PCA)表明,铜鱼和圆口铜鱼摄食器官形态特征存在一定的差异.长江宜宾江段铜鱼和圆口铜鱼种间竞争不激烈,作为向家坝蓄水前最后一次对长江宜宾江段铜鱼和圆口铜鱼食性及种间食物关系的调查,研究结果可为分析向家坝蓄水对宜宾江段鱼类营养结构的影响提供数据参考.     

饲料能量密度和投喂水平对吉富罗非鱼生长和健康的影响

为探讨饲料能量密度(DED)和投喂水平(DFR)对鱼类生长和健康的影响,本试验采用2×2双因子设计,设置2个DED(对照组和高糖高脂组)和2个DFR(1倍和1.2倍表观饱食投喂对照组饲料的能量水平),研究DED和DFR对吉富罗非鱼[Oreochromis niloticus,(14.59±0.06)g]生长性能、饲料利...     

The role of hepatic, renal and intestinal gluconeogenic enzymes in glucose homeostasis of juvenile rainbow trout

Rainbow trout is unable to utilize high levels of dietary carbohydrates and experiences hyperglycemia after consumption of carbohydrate-rich meals. Carbohydrates stimulate hepatic glycolytic activity, but gene expression of the rate-limiting gluconeogenic enzymes glucose-6-phosphatase (G6Pase), fructose-1,6-bisphosphatase (FBPase) and phosphoenolpyruvate carboxykinase (PEPCK) remains high. Although there is significant mRNA expression and activity of gluconeogenic enzymes in trout intestine and kidney, the regulation of these enzymes by diet is not known. We tested the hypothesis that dietary carbohydrate modulates intestinal and renal G6Pase, FBPase and PEPCK. Fish were either fasted or fed isocaloric carbohydrate-free (CF) or high carbohydrate (HC) diets for 14 days. As expected, fish fed HC exhibited postprandial hyperglycemia and enhanced levels of hepatic glucokinase mRNA and activity. Dietary carbohydrates had no significant effect on the expression and activity of PEPCK, FBPase and G6Pase in all three organs. In contrast, fasting enhanced the activity, but not the mRNA expression of both hepatic and intestinal PEPCK, as well as intestinal FBPase. Therefore, the activity of rate-limiting gluconeogenic enzymes in trout can be modified by fasting, but not by the carbohydrate content of the diet, potentially causing hyperglycemia when fed high levels of dietary carbohydrates. In this species consuming low carbohydrate diets at infrequent intervals in the wild, fasting-induced increases in hepatic and intestinal gluconeogenic enzyme activities may be a key adaptation to prevent perturbations in blood glucose during food deprivation. Presented in part at Experimental Biology, April 2006, San Francisco, CA [Kirchner S., Panserat S., Kaushik S. and Ferraris R. FASEB-IUPS-2006 A667.6].     

Gluconeogenic enzyme gene expression is decreased by dietary carbohydrates in common carp (Cyprinus carpio) and gilthead seabream (Sparus aurata)

Our objective is to understand the low metabolic utilization of dietary carbohydrates in fish. We compared the regulation of gluconeogenic enzymes at a molecular level in two fish species, the common carp (Cyprinus carpio) and gilthead seabream (Sparus aurata), known to be relatively tolerant to dietary carbohydrates. After cloning of partial cDNA sequences for three key gluconeogenic enzymes (glucose-6-phosphatase (G6Pase), fructose biphosphatase (FBPase) and phosphoenolpyruvate carboxykinase (PEPCK) in the two species, we analyzed gene expressions of these enzymes 6 and 24 h after feeding with (20%) or without carbohydrates. Our data show that there is at least one gluconeogenic enzyme strongly regulated (decreased expression after feeding) in the two fish species, i.e. the PEPCK for common carp and G6Pase/FBPase for gilthead seabream. In these fish species, the regulation seems to be similar to the mammals at least at the molecular level.     

Dietary carbohydrates induce changes in glucosensing capacity and food intake of rainbow trout

We hypothesize that variations in dietary carbohydrate levels produce changes in glucosensor parameters in previously characterized glucosensing areas (hypothalamus and hindbrain) related with the regulation of food intake of a carnivorous fish species like rainbow trout. Therefore, we fed trout with standard, carbohydrate-free (CF) or high-carbohydrate (HC) diets for 10 days to assess changes in glucosensing system and food intake. Fish fed CF diet displayed hypoglycemia and increased food intake. Fish fed a HC diet displayed hyperglycemia and decreased food intake. Changes in food intake due to dietary carbohydrates were accompanied in hypothalamus and hindbrain of fish fed with HC diet by changes in parameters involved in glucosensing, such as increased glucose, glucose 6-phosphate, and glycogen levels and increased glucokinase (GK), glycogen synthase, and pyruvate kinase activities as well as increased GK and GLUT2 expression. All those results address for the first time in fish, despite the relative intolerance to glucose of carnivorous species, that dietary carbohydrates are important regulators of the glucosensing system in carnivorous fish, suggesting that the information generated by this system can be associated with the changes observed in food intake.     

大亚湾养殖鱼类寄生车轮虫的种类组成与季节动态

2017年8月至2018年7月对大亚湾8种养殖鱼类的车轮虫感染情况进行了调查, 采用Lom倡导的“统一特定方法”及Van As & Basson提出的“齿体定位描述法”对采获的车轮虫标本进行了形态鉴定与描述。结果在卵形鲳鲹(Trachinotus ovatus)、星点笛鲷(Lutjanus stellatus)、鞍带石斑鱼(Epinephelus lanceolatus)、眼斑拟石首鱼(Sciaenops ocellatus)和虎龙杂交斑[E. fuscoguttatus (♀) × E. lanceolatus (♂)]等5种鱼上共检获5种车轮虫: 亚卓车轮虫(Trichodina jadranica)、莱普斯车轮虫(T. lepsii)、长须鳠车轮虫(T. guliae)、劳牧小车轮虫(Trichodinella lomi)和斜拟车轮虫(Paratrichodina oblique); 其中卵形鲳鲹5种虫均有寄生, 虎龙杂交斑感染了4种虫, 星点笛鲷、眼斑拟石首鱼和鞍带石斑鱼分别感染了3种、2种和1种虫。周年感染数据表明: 5种虫的感染率均以卵形鲳鲹最高, 眼斑拟石首鱼上2种虫的感染率最低; 莱普斯车轮虫平均感染强度最高的宿主是虎龙杂交斑, 其他4种虫的均是卵形鲳鲹。寄生车轮虫的季节动态表明: 冬季的感染率和平均感染强度较低; 不同虫种感染高峰出现的季节不一, 其中斜拟车轮虫的感染高峰出现在秋季, 其春夏秋季的平均感染强度均大于其他4种虫。研究填补了大亚湾海区鱼类寄生车轮虫研究的空缺, 为该海区车轮虫病的诊断与防控提供了参考。     

洱海鲢、鳙的食物组成及与太湖新银鱼的食性重叠研究

为了研究鲢（Hypophthalmichthys molitrix）、鳙（Aristichthys nobilis）两种鱼食物组成的空间变化,分析了2010年7月至2011年10月在洱海古生和北部两采样点逐月采集或收集的共93尾鲢和71尾鳙的肠道内含物,对其食物组成的季节变化、空间变化及与太湖新银鱼（Neosalanx taihuensis）的食物重叠进行了研究。结果表明,鲢、鳙全年摄食的饵料生物数分别为75 属和 64属。根据相对重要性指数（IRI%）,微囊藻（Microcystis）和象鼻溞（Bosmina）为两种鱼的主要饵料类群。鲢、鳙的食物组成呈明显的季节变化,这与饵料生物的季节变化密切相关。在空间上,两种鱼在古生摄食的浮游植物比例大于北部,这是由不同区域饵料生物组成差异导致的结果。Schoener重叠指数显示鲢、鳙与太湖新银鱼之间的食性重叠不显著（E0.6）。       

环境因子对卵形鲳鲹幼鱼耗氧率和排氨率的影响

运用封闭流水式实验方法研究温度、盐度、pH和流速对卵形鲳鲹(Trachinotus ovatus)幼鱼耗氧率和排氨率的影响.实验结果表明,随着温度的升高,耗氧率和排氨率均是先增大后减小,当温度为27℃时,耗氧率和排氨率达最大值,温度对卵形鲳鲹幼鱼耗氧率和排氨率的影响显著(P＜0.0l);耗氧率和排氨率随着盐度的升高均出...     

Interspecific dietary diversity has little influence on pathways of glucose metabolism in liver and heart of piranhas and pacus (family Serrasalmidae)

The Serrasalmidae is a speciose family of Neotropical freshwater fishes with diverse interspecies dietary preferences, from the herbivorous or frugivorous pacus to the omnivorous or carnivorous piranhas. The Serrasalmidae is an ideal comparative model to explore the biochemical correlates of dietary preference. For example, debate exists about whether variation in dietary preference among fishes influences the capacities for de novo glucose synthesis (gluconeogenesis) or glucose use as metabolic fuel (glycolysis). We predicted that carnivory in piranhas would be associated with an enhanced gluconeogenic capacity compared with the herbivorous pacus, because carnivores consume less carbohydrate. As a corollary, we expected similar glycolytic capacities at a major site of glucose use (heart) in fishes with different diets. We measured activities of key enzymes of gluconeogenesis and the opposing reactions of glycolysis in liver (the primary gluconeogenic site) and heart of five serrasalmid species showing an interspecies dietary gradient from herbivory to omnivory to carnivory. The interspecific variation in enzyme activities was, in general, unrelated to dietary preference. Glycolytic capacity in heart was lower in herbivores but this may be related to non-diet factors. Among serrasalmid fishes, the enzymatic capacities of glucose metabolism are not overtly influenced by interspecific divergence of dietary preference.     

Cytosolic phosphoenolpyruvate carboxykinase does not solely control the rate of hepatic gluconeogenesis in the intact mouse liver

When dietary carbohydrate is unavailable, glucose required to support metabolism in vital tissues is generated via gluconeogenesis in the liver. Expression of phosphoenolpyruvate carboxykinase (PEPCK), commonly considered the control point for liver gluconeogenesis, is normally regulated by circulating hormones to match systemic glucose demand. However, this regulation fails in diabetes. Because other molecular and metabolic factors can also influence gluconeogenesis, the explicit role of PEPCK protein content in the control of gluconeogenesis was unclear. In this study, metabolic control of liver gluconeogenesis was quantified in groups of mice with varying PEPCK protein content. Surprisingly, livers with a 90% reduction in PEPCK content showed only a approximately 40% reduction in gluconeogenic flux, indicating a lower than expected capacity for PEPCK protein content to control gluconeogenesis. However, PEPCK flux correlated tightly with TCA cycle activity, suggesting that under some conditions in mice, PEPCK expression must coordinate with hepatic energy metabolism to control gluconeogenesis.     

Effects of dietary fibre on the intestinal absorption of dextrin, blood sugar level and growth of tilapia, Oreochromis niloticm × O. aureus

The roles of five different dietary fibres (cellulose, agar, guar gum, carrageenan and carboxy-methylcellulose) each as 10% wt/wt added into the diet, affecting the intestinal sugar absorption, blood sugar level and utilization of dextrin were studied in hybrid tilapia, Oreochromis niloticus × O. aureus ; dextrin and glucose were also included in the study as controls for comparison. There were seven dietary groups: each diet was fed to three aquaria each containing 15 fish. The experiment was carried out in a closed circulation, filtered, rearing system for 2 months. The results indicated that the weight gain percentage and food conversion ratio were significantly (P<0.05) lower in tilapia fed fibre-containing diets than those of tilapia fed dextrin or glucose diet. The intestinal absorption of carbohydrate and the blood sugar content of tilapia were low when diets contained fibre, regardless of the source.