复合酸化剂对鲤生长及消化酶活性的影响

在鲤鱼(Cyprinus carpio)基础饲料中,分别添加不同梯度的复合酸化剂(质量分数分别为0、0.2%、0.3%),研究复合酸化剂对其生长和消化酶活性的影响。结果表明:1)添加复合酸化剂显著(P<0.05)提高鲤鱼的相对增重率、特定生长率、饵料转化效率、饲料蛋白质效率以及饲料蛋白质沉积率等生长性能指标;2)添加质量分数0.3%的复合酸化剂时,鲤鱼肝胰脏、前肠和中肠的蛋白酶活性显著提高(P<0.05),酸化剂组的淀粉酶和脂肪酶活性有升高的趋势,但与对照组差异不显著;3)鱼体的粗蛋白质、粗脂肪、粗灰分、水分、肥满度及内脏比等品质指标在各组间差异不显著。综上所述,鲤鱼饲料中添加以柠檬酸、乳酸、磷酸等为主的复合酸化剂,可显著提高鲤鱼肝胰脏、前肠和中肠的蛋白酶活性,促进鲤鱼生长。     

Occurrence of Bothriocephalus acheilognathi (Cestoda, Bothriocephallidea) in grass carp Ctenopharyngodon idella in the Changjiang River drainage

Bothriocephalus acheilognathi is a potentially serious pathogen in wild or cultured fish in worldwide distribution. We examined 58-farmed grass carp from Nanchang in the Changjiang (Yangtze) River drainage, from which 20.7% were found to harbor the parasite with an infection intensity of 36.9±54.7. The parasites were identified based on morphology and rDNA ITS sequence analysis. The present report represents the first record of the parasite in grass carp Ctenopharyngodon idella in the river drainage.     

Integrated biological control of water hyacinths, Eichhornia crassipes by a novel combination of grass carp, Ctenopharyngodon idella (Valenciennes, 1844), and the weevil, Neochetina spp.

The efficacy of grass carp Ctenopharyngodon idella (Cyprinidae) and weevils Neochetina spp. (Curculionidae) to control the aquatic weed, water hyacinth, is investigated in a square net cage (happas) setting at a farm in Cuddalore District, South India. This novel combination of insects and fish is found to be superior to individual treatments for controlling the weed growth within 110 d. The biomass of the weed, number of plants, percentage of flowered plants and chlorophyll contents were studied. The weed biomass is reduced from 5 kg (day 1) to 0.33 kg (day 110) when exposed to grass carp and weevils. The number of plants is reduced to 0.75 in grass carp and weevil exposed happas, while it is 741.5 in the control. The mean number of leaves per plant is also reduced. In addition, the chlorophyll a and b are significantly reduced in happas exposed to the combination of fish and insects when compared to the other treatments. Based on the results of this study, we consider the combined use of grass carp and weevils to be more efficient and sustainable for managing water hyacinths than the use of these organisms individually.     

草鱼种质退化相关SRAP分子标记的筛选

采用相关序列扩增多态性(sequence-realted amplified polymorphism,SRAP)技术分析野生草鱼和家养草鱼,并筛选与草鱼种质退化相关的分子遗传标记。共进行88对引物组合的检测,产生标记数目共计905个。依据标记在群体中出现的频率和变化规律,共筛选出21个可能与种质相关的特异性标记,对这些特异性标记进行测序并将测序结果进行BLAST分析,发现测得片段中有8个片段能在GeneBank中找到同源性较高的序列,而其他片段与数据库中序列的相似性较低。     

Molecular cloning and mRNA expression analysis of myosin heavy chain (MyHC) from fast skeletal muscle of grass carp, Ctenopharyngodon idella

The myosin heavy chain (MyHC) is one of the major structural and contracting proteins of muscle. We have isolated the cDNA clone encoding MyHC of the grass carp, Ctenopharyngodon idella. The sequence comprises 5 934 bp, including a 5 814 bp open reading frame encoding an amino acid sequence of 1 937 residues. The deduced amino acid sequence showed 69% homology to rabbit fast skeletal MyHC and 73%–76% homology to the MyHCs from the mandarin fish, walleye pollack, white croaker, chum salmon, and carp. The putative sequences of subfragment-1 and the light meromyosin region showed 61.4%–80% homology to the corresponding regions of other fish MyHCs. The tissue-specific and developmental stage-specific expressions of the MyHC gene were analyzed by quantitative real-time PCR. The MyHC gene showed the highest expression in the muscles compared with the kidney, spleen and intestine. Developmentally, there was a gradual increase in MyHC mRNA expression from the neural formation stage to the tail bud stage. The highest expression was detected in hatching larva. Our work on the MyHC gene from the grass carp has provided useful information for fish molecular biology and fish genomics.     

Protective effects of C-phycocyanin on alcohol-induced acute liver injury in mice

Excessive alcohol consumption leads to liver disease. Extensive evidence suggests that C-phycocyanin (C-PC), a chromophore phycocyanobilin derived from Spirulina platensis, exerts protective effects against chemical-induced organ damage. In this study, we investigated whether C-PC could protect against ethanol-induced acute liver injury. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), triglyceride (TG), total cholesterol (CHOL), low-density lipoprotein (LDL), liver homogenate malondialdehyde (MDA), superoxide dismutase (SOD) content were measured, and pathological examination of liver sections were examined. C-PC showed obvious inhibitory effects on serum ALT, AST, TG, CHOL, LDL and MDA, and SOD content significantly increased in the liver. The structure of hepatic lobules was clear, liver sinus returned to normal, and liver cell cords were arranged in neat rows. Cloudiness, swelling, inflammatory cell infiltration and spotty necrosis of liver cells were significantly reduced. Therefore, C-PC can significantly protect against ethanol-induced acute liver injury.     

Histopathological alterations in the liver and intestine of Nile tilapia Oreochromis niloticus exposed to long-term sublethal concentrations of cadmium chloride

Fingerlings of Nile tilapia Oreochromis niloticus were exposed to 1.68, 3.36, and 5.04 mg/L cadmium(as CdCl2), which represent 10%, 20%, and 30% of their previously determined 96-h LC5 0. After exposure for 20 days, sections of the liver and intestine of treated fish were examined histologically. Histopathological changes varied from slight to severe structural modification, depending on the exposure concentration. The hepatic tissues of fish exposed to 10% LC 50 showed markedly increased vacuolation of the hepatocytes and coarse granulation of their cytoplasm. Abundant erythrocytic infiltration among the hepatocytes was observed in fish exposed to 20% LC5 0. In the intestinal tissues of fish exposed to all doses, goblet cells proliferated and were greatly increased in size, the longitudinal muscularis mucosa was disturbed and, in the crypts of the sub-mucosal layer, apoptosis increased, indicated by large numbers of degenerated nuclei. Large numbers of inflammatory cells and dilated blood vessels were observed in the intestine of the group treated with 30% LC5 0.     

溶藻弧菌胞外产物注射赤点石斑鱼后的组织病理学观察

在注射溶藻弧菌胞外产物(ECP)48 h后,石斑鱼Epinephelus akaara出现死亡,临床症状表现为:运动迟缓,体色变深,腹部膨大,腹腔有明显的积水,肝脏出血有花斑,肾脏和脾脏肿大。病理组织切片观察发现:肝细胞坏死,解体,界限模糊,细胞核变形、裂解甚至消失;肝脏出血,肝索中有红细胞浸润,有的红细胞变形甚至破裂;肾小管上皮细胞脱落、坏死;肠粘膜上皮细胞脱落、坏死,微绒毛不整齐,模糊不清,脱落;脾窦和脾索不清晰,分界不清,且在脾窦和脾索中分布着大量的、形态不规则的红细胞。此外,还发现在肝脏、脾脏、肾脏、肠壁肌层、心肌和鳃等组织中存在一种相同结构,该结构有平滑肌环绕,管腔内壁衬以扁平上皮细胞,管腔中含有一团染成紫红色的物质,经推断为小动脉透明样变性,而在正常的组织切片中,均无此结构。     

Comparison of intestinal bacterial communities in grass carp, Ctenopharyngodon idellus, from two different habitats

The intestinal bacteria of vertebrates form a close relationship with their host.External and internal conditions of the host,including its habitat,affect the intestinal bacterial community.Similarly,the intestinal bacterial community can,in turn,influence the host,particularly with respect to disease resistance.We compared the intestinal bacterial communities of grass carp that were collected from farm-ponds or a lake.We conducted denaturing gradient gel electrophoresis of amplified 16S rRNA genes,from which 66 different operational taxonomic units were identified.Using both the unweighted pair-group method with arithmetic means clustering and principal component analysis ordination,we found that the intestinal bacterial communities from the two groups of pond fish were clustered together and inset into the clusters of wild fish,except for DF-7,and there was no significant correlation between genetic diversity of grass carp and their intestinal bacterial communities(Mantel one-tailed test,R=0.157,P=0.175).Cetobacterium appeared more frequently in the intestine of grass carp collected from pond.A more thorough understanding of the role played by intestinal microbiota on fish health would be of considerable benefit to the aquaculture industry.     

Lipid and fatty acid compositions of cod (<Emphasis Type="Italic">Gadus morhua</Emphasis>), haddock (<Emphasis Type="Italic">Melanogrammus aeglefinus</Emphasis>) and halibut (<Emphasis Type="Italic">Hippoglossus hippoglossus</Emphasis>)

This study was conducted to compare lipid and fatty acid composition of cod, haddock and halibut. Three groups of cod (276 g ± 61 g), haddock (538 g ± 83 g) and halibut (3704 g ± 221 g) were maintained with commercial feeds mainly based on fish meal and marine fish oil for 12 weeks prior to sampling. The fatty acid compositions of muscle and liver were determined by GC/FID after derivatization of extracted lipids into fatty acid methyl esters (FAME). Lipids were also fractionated into neutral and polar lipids using Waters silica Sep-Pak?. The phospholipid fraction was further separated by high-performance thin-layer chromatography (HPTLC) and the FAME profile was obtained. Results of the present study showed that cod and haddock were lean fish and their total muscle lipid contents were 0.8% and 0.7%, respectively, with phospholipid constituting 83.6% and 87.5% of the total muscle lipid, respectively. Halibut was a medium-fat fish and its muscle lipid content was 8%, with 84% of the total muscle lipid being neutral lipid. Total liver lipid contents of cod, haddock and halibut were 36.9%, 67.2% and 30.7%, respectively, of which the neutral lipids accounted for the major fraction (88.1%–97.1%). Polyunsaturated fatty acids were the most abundant in cod and haddock muscle neutral lipid. Monounsaturated fatty acid level was the highest in halibut muscle neutral lipid. Fatty acid compositions of phospholipid were relatively constant. In summary, the liver of cod and haddock as lean fish was the main lipid reserve organ, and structural phospholipid is the major lipid form in flesh. However, as a medium-fat fish, halibut stored lipid in both their liver and muscle.     

草鱼网围养殖区声波的研究

对网围养殖区内草鱼的活动声波进行了采集与分析,并将采集的声波进行了回放。结果表明,草鱼网围养殖区声波频率范围为0~3.2 kHz,整个频段内没有宽带波峰。在草鱼饥饿、食饵和饱食的不同状态下养殖区内的水声特性有一定的差异。研究表明在网围养殖区通过声波回放能对草鱼起到诱集作用,在投饵回放、投饵不回放及不投饵回放声波的情况下,草鱼的响应时间分别为2.55、3.504、.80 min,存在显著差异。回放持续性声波和间隔性声波在响应时间上不存在显著差异。     

Development of intermediate foodstuff derived from freshwater fish in China

According to the three-dimensional contour maps showing the gel-forming properties of surimi derived from freshwater fish, 8 species of surimi were classified into two types. The-valley type surimi （silver carp, big-head carp, Chinese snake head and blunt snout bream） shows easy setting, low resistance to gel collapse, high enhancement ability with two-step heating, and narrow optimum heating temperature and time area, which are of the same characteristics as the walleye pollack surimi. In contrast, the Plateau type surimi （tilapia, grass carp, mud carp and common carp） exhibits difficult setting, high resistance to gel collapse, no enhancement ability with two-step heating, and wide optimum heating temperature and time area. There are seasonal changes of gelling properties of silver carp surimi, and the setting ability of surimi gel is higher in winter and lower in summer. The marine fish meat gels and the freshwater fish meat gels have the same acceptability for inland Chinese according to the sensory evaluation results. A slight increase in sensory scorings of kamaboko gels occurred when the extract from walleye pollack muscle was added, especially in the odor scoring of silver carp kamaboko gels.     

Impact of the Three Gorges Dam on reproduction of four major Chinese carps species in the middle reaches of the Changjiang River

Silver carp (Hypophthalmichthys molitrix), bighead carp (Aristichthys nobilis), grass carp (Ctenopharyngodon idella), and black carp (Mylopharyngodon piceus) are the four major Chinese carps and are commercially important aquaculture species in China. Reproduction of these carp has declined since the construction of the Three Gorges Dam (TGD) due to an altered water flow and thermal regime in the Changjiang (Yangtze) River. However, details of the changes in reproduction of the four species are not well understood. To assess the impact of the TGD on reproduction of the four carp, we investigated their eggs and larvae at Yidu City, which is 80 km below the TGD, during 2005–2012. We examined diff erences in larval abundance of the four species in the Jianli section (350 km downstream of the TGD) before (1997–2002) and after (2003–2012) construction of the TGD. Based on these observations, the first spawning date of the four species was delayed a mean of about 25 days after the dam was constructed. Mean egg abundance in the Yidu section of the river was 249 million and mean larval abundance was 464 million, which were significant decreases since the 1980s. Moreover, larval abundance in the Jianli section after the dam was constructed was significantly lower than that before construction (ANCOVA, P<0.05). The observed larval abundance accounted for only 24.66% of the predicted value in 2003 when the dam was first inundated. The present spawning grounds between the TGD and Yidu section of the river are very similar to those described in the 1980s, and some spawning grounds exist upstream of the TGD. Large free-flowing stretches upstream of the TGD and the creation of artificially flooded downstream reaches are needed to stimulate spawning and eff ectively conserve these four major Chinese carps species.     

Structure and Classification of Haemocytes in the Bivalve Mollusc Meretrix meretrix

Light and electron microscopic studies were carried out in order to characterize haemocytes in the bivalve mollusc Meretrix meretrix. According to nucleus and cytoplasm characters, four types of haemocytes were recognized： agranular haemocytes, lymphoid haemocyte, large granular and small granular haemocytes. Agranular hamocyte is the main cell type, accounting for 75%. It is agranular with rich organelles in cytoplasm, including mitochondria, golgi body and endoplasmic reticulum. Glycogen deposits were usually found in this cell type. The number of lymphoid haemocyte accounts for 1% - 2%. This cell type is agranular and shows a high ratio of nucleus to cytoplasm. A few organelles were found. High electrondense granules with diameters of 0.2 - 0.5μm and rich organelles were found in small granular haemocyte. The proportion of this cell type is about 15%. Rich granules of high electron-dense with diameters of 0.8- 2.4μm were found in large granular haemocyte. The proportion of this cell type is about 10%, and the quantity of organelles is the least.     

ENCLOSURE EXPERIMENTS ON AND LACUSTRINE PRACTICE FOR ELIMINATING MICROCYSTIS BLOOM

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Effect of dietary cottonseed meal on growth performance,physiological response,and gossypol accumulation in pre-adult grass carp, <Emphasis Type="Italic">Ctenopharyngodon idellus</Emphasis>

Cottonseed meal (CM) was used at up to 36.95% content in the diet (replacing 60% of dietary fish meal protein) without any negative eff ects on growth performance of pre-adult grass carp (initial body weight, 761 g) under outdoor conditions. A culture trial was conducted in net cages installed in a large concrete pond. Seven isonitrogenous and isoenergetic diets containing a gradient of CM concentrations (0, 12.2%, 24.4%, 36.6%, 48.8%, 54.8%, and 61.0%) as replacement for dietary fish meal protein (0, 20%, 40%, 60%, 80%, 90%, and 100%) were formulated. Dietary non-resistant starch (from maize) was inverse to dietary CM. Growth performance and feed utilization of fish fed the diets containing CM replacing 0–40% fishmeal protein were not aff ected after the 6-week feeding trial. Accumulation of hepatopancreatic total gossypol in the hepatopancreas was significantly correlated with free gossypol content in the diets (HTG=88.6+1.5×DFG, R ²=0.89, P<0.05). Intestinal α-amylase and γ-glutamyl transpeptidase activities rose along with increasing dietary CM level. The structure of the mid-intestinal tissues and the ultrastructure of the enterocyte microvilli were normal when dietary CM was <36.6% (60% protein replacement). Increasing dietary CM content increased serum alanine aminotransferase levels but decreased serum alkaline phosphatase, cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, and albumin (P<0.05).     

Lipid and Fatty Acid Compositions of Cod(Gadus morhua),Haddock(Melanogrammus aeglefinus)and Halibut(Hippogiossus hippoglossus)

This study was conducted to compare lipid and fatty acid composition of cod,haddock and halibut.Three groups of cod(276 g±61 g),haddock(538 g±83 g)and halibut(3704 g±221 g)were maintained with commercial feeds mainly based on fish meal and marine fish oil for 12 weeks prior to sampling.The fatty acid compositions of muscle and liver were determined by GC/FID after derivatization of extracted lipids into fatty acid methyl esters(FAME).Lipids were also fractionated into neutral and polar lipids using Waters silica Sep-Pak(R).The phospholipid fraction was further separated by high-performance thin-layer chromatography(HPTLC)and the FAME profile was obtained.Results of the present study showed that cod and haddock were lean fish and their total muscle lipid contents were 0.8% and 0.7%,respectively,with phospholipid constituting 83.6% and 87.5% of the total muscle lipid,respectively.Halibut was a medium-fat fish and its muscle lipid content was 8%,with 84% of the total muscle lipid being neutral lipid.Total liver lipid contents of cod,haddock and halibut were 36.9%,67.2% and 30.7%,respectively,of which the neutral lipids accounted for the major fraction(88.1%-97.1%).Polyunsaturated fatty acids were the most abundant in cod and haddock muscle neutral lipid.Monounsaturated fatty acid level was the highest in halibut muscle neutral lipid.Fatty acid compositions of phospholipid were relatively constant.In summary,the liver of cod and haddock as lean fish was the main lipid reserve organ,and structural phospholipid is the major lipid form in flesh.However,as a medium-fat fish,halibut stored lipid in both their liver and muscle.     

Experimental studies on the role of planktivorous fishes in the elimination ofMicrocystis bloom from Donghu Lake using enclosure method

The hypertrophic subtropic Donghu Lake's dense water bloom (of mainlyMicrocystis, Anabaena andOscillatoria) that occurred annually from the beginning of the 1970s, has disappeared since 1985. The influence of planktivorous fishes (silver and bighead carps) on the water bloom was studied for three years using the enclosure method. The enclosures stocked densely with bighead and/or silver carp were free of water bloom during the experimental period. The water bloom that appeared in the fish-free enclosures was completely eliminated in 10–20 days by introduction of silver and/or bighead carp(grass carp was not effective in controlling water bloom). This study showed clearly that grazing pressure by planktivorous fishes is a key factor in eliminating water bloom from the lake. This work was supported by FEBL (State Key Laboratory for Freshwater Ecology and Biotechnology of China) funds and by the National Natural Science Foundation of China (Grant No., 3937014).     

Long-Term Effects of Docosahexaenoic Acid-Bound Phospholipids and the Combination of Docosahexaenoic Acid-Bound Triglyceride and Egg Yolk Phospholipid on Lipid Metabolism in Mice

The bioavailability of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) depends on their chemical forms. This study investigated the long-term effects of DHA-bound triglyceride (TG-DHA), DHA-bound phospholipid (PL-DHA), and the combination of TG-DHA and egg yolk phospholipid (Egg-PL) on lipid metabolism in mice fed with a high-fat diet (fat levels of 22.5%). Male C57BL/6J mice were fed with different formulations containing 0.5% DHA, including TG-DHA, PL-DHA, and the combination of TG-DHA and Egg-PL, for 6 weeks. Serum, hepatic, and cerebral lipid concentrations and the fatty acid compositions of the liver and brain were determined. The concentrations of serum total triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-c), and hepatic TG in the PL-DHA group and the combination group were significantly lower than those in the high-fat (HF) group (P < 0.05). Atherogenic index (AI) of the PL-DHA group was significantly lower than that of the combination group (P < 0.05). Hepatic TC level in the combination group was significantly lower than that in the HF group (P < 0.05), but no significant difference was observed between the combination group and the PL-DHA group. Both the PL-DHA and the combination groups showed significantly increased DHA levels in the liver compared with the HF group (P < 0.05). However, there were no obvious increases in the cerebral DHA levels in all DHA diet groups. These results suggest that PL-DHA was superior to the combination of TG-DHA and Egg-PL in decreasing the AI. Long-term dietary supplementation with low amount of DHA (0.5%) may improve hepatic DHA levels, although cerebral DHA levels may not be enhanced.     

Effects of dietary carbohydrate-to-lipid ratio on the growth performance and feed utilization of juvenile turbot (<Emphasis Type="Italic">Scophthalmus maximus</Emphasis>)

A 9-week feeding trial was conducted to investigate the effects of dietary carbohydrate to lipid ratio(CHO:LIP) on the growth performance and feed utilization of juvenile turbot Scophthalmus maximus(initial body weight 8.75 g ± 0.04 g). Four isonitrogenous and isoenergetic low protein level(39%) diets were formulated with increasing ratios of dietary carbohydrate to lipid(2:18, 6:18, 18:12 and 28:6). A high protein level(50%) diet with the 2:12 ratio of carbohydrate to lipid was used as the control. Results showed that the survival rate, contents of moisture, crude protein and ash in muscle were not significantly affected by dietary treatments. With the dietary CHO:LIP ratio increased from 2:18 to 18:12, weight gain rate significantly increased(P < 0.05). Higher dietary CHO:LIP ratio(28:6) resulted in the significantly decreased weight gain rate(P < 0.05). Meanwhile, this treatment also resulted in the highest daily feed intake and liver glycogen content, as well as the lowest feed efficiency(P < 0.05). Muscle glycogen content in fish fed the diet with 2:12 or 2:18 CHO:LIP ratio was significantly lower than those fed with the other three diets(P < 0.05). The present results confirmed that the juvenile turbot can utilize carbohydrate. Furthermore, the appropriate ratio of dietary carbohydrate to lipid was important to the growth and feed utilization of turbot. The proper CHO:LIP ratio based on the growth performance in the present study was determined to be 18:12 when the dietary protein level was 39%.