卤虫投喂下长吻(鱼危)仔稚鱼消化酶发育和口宽变化的研究

采用酶学和形态学测定方法, 研究在投喂卤虫条件下长吻(鱼危)仔鱼4种主要消化酶: 胃蛋白酶、胰蛋白酶、脂肪酶和淀粉酶的活性变化以及长吻(鱼危)仔鱼口宽、全长变化。实验共进行13d, 实验结果表明: (1)长吻(鱼危)仔鱼全长、口宽的发育与其日龄表现出明显的线性正相关(R_TL²=0.974, R_MW²=0.964)。口宽与全长比值(MW/TL)在仔鱼开口后急剧下降, 并自7日龄开始维持在0.07—0.08, 口宽和全长处于同步发育期并表现出明显的相关性(R²=0.948), 说明7日龄(/h, days post hatching)后口宽和全长处于同步发育期, 标志仔鱼转食的开始。(2)长吻(鱼危)仔鱼初次开口时即可检测出四种消化酶的活性。5—7/h时胰蛋白酶显著高于初孵仔鱼, 与此时仔鱼开始开口摄食的行为相一致。胃蛋白酶、脂肪酶活性在仔鱼孵化后第7天即开口的第3天, 淀粉酶活性在孵化后第6天, 显著高于初次孵化出来的仔鱼。8—13/h时, 胃蛋白酶、胰蛋白酶、脂肪酶和淀粉酶活性均在较高水平平稳的波动, 标志着消化道发育逐渐健全。     

不同饲料营养对池塘养殖长吻(鱼危)生长性能和鱼肉品质的影响

研究通过90d的投喂实验研究不同配方饲料对池塘养殖长吻(鱼危)(Leiocassis longirostris Günther)生长性 能和鱼肉品质的影响.实验使用5种饲料 (Cont:对照、HP:高蛋白、HC:高糖、HL:高脂和HE:高能). 结果发现:HC组鱼体生长最差,而HP组特定生长率(SGR)和饲料效率(FE)都最高.鱼体水分和脂肪含量变 化趋势相反,HL组最低,HE组略高,HP组最高.鱼体脂肪主要分布于内脏,在HL和HE组显著增高,导致 出肉率(yield)显著降低,氧化产物丙二醛(MDA)增多.投喂实验结束时,鱼体背部黄度(B~*)HC组最高,HE组 其次,HP组最低,腹部红度(a~*)HE组最高,HL组次之,HP组最低.新鲜肉色各处理无差异,冰冻3d后,鱼 肉L~*和白度(△E)HE组最高,HL,组其次,Cont组最低;鱼肉a~*Cont组最高,HL组其次,HP组最低.新鲜鱼 肉硬度、胶黏性均为HP组最高,Cont组其次,HE组最低,其他肉质指标均无显著差异:结果表明:饲料营 养中脂肪是影响肉质最明显的因素,饲料脂肪通过控制鱼体成分影响鱼体体色、肉质,以及冰冻储存产生的 MDA;冰冻储存显著降低鱼肉品质,冰冻后鱼肉硬度、胶黏性、咀嚼性和系水力都明显降低,黏附性明显增 大,该指标的变化是肉质降低的表现.     

不同饵料对稀有鳇鲫仔稚鱼生长、消化道及消化酶的影响

为了筛选稀有逗鲫(Gobiocypris rarus)仔稚鱼期合适的饵料, 将初孵仔鱼随机分为3个组: 活饵组、饲料组、转食组, 每组3个平行, 均从3 dah(day after hatching)开始投喂相应饵料, 在10、15、20、25、30、35 dah时统计生长指标和存活率, 并进行35 dah仔稚鱼消化道组织学及消化酶活性研究。结果显示: (1)35 dah时, 活饵组存活率最高; (2)从15 dah开始, 活饵组表现出最好的生长性能, 并维持这种趋势; (3)活饵组的消化道各部肌层厚度、黏液细胞数目均最高, 提示该组仔稚鱼消化道发育状态较好, 并具有较优的消化吸收能力; (4)转食组胰蛋白酶活性显著高于活饵组和饲料组。研究结果提示: 相对于饲料和转食, 一直投喂活饵更有利于稀有逗鲫仔稚鱼的生长和发育。建议在标准化养殖过程中, 对仔稚鱼期的稀有逗鲫采取活饵投喂的方式。     

哲罗鱼稚鱼最佳投喂策略

为探讨哲罗鱼稚鱼的最佳投喂策略,设置了饥饿再投喂试验、饥饿再投喂恢复试验以及日投喂频率试验.结果表明: 饥饿再投喂试验中,各饥饿组未表现出补偿生长现象.但在饥饿再投喂恢复试验中,各饥饿组表现出不同程度的补偿生长,其中S_1/2组(饥饿1/2 d投喂1/2 d)体质量的增加量与对照组接近,表现出完全补偿生长.表明在哲罗鱼早期稚鱼阶段(体质量0～2 g,水温9～15.3 ℃),S_1/2是可以考虑使用的投喂方法.日投喂频率试验中,T₃组(日投喂3次)体长、体质量的增加量以及特定生长率均最高,饵料转化率也相对较高.表明在哲罗鱼后期稚鱼阶段(体质量2～21 g,水温8.8～15.5 ℃),以日投喂3次为宜.     

投喂策略对黄颡鱼生长和繁殖的影响

实验设置饱食投喂(AS)、80%饱食(80AS)、50%饱食(50AS)及先饥饿34d后再饱食投喂31d (HAS)四个处理组,饲养初重(86.6±0.41) g的雌性黄颡鱼(Pelteobagrus fulvidraco) 65d,于实验中期(34d)和实验结束时取样,以探究投喂策略对黄颡鱼母本生长性能和繁殖能力的影响。实验结果显示:80AS组、50AS组和HAS组的总摄食量基本符合实验设计的比例且显著低于AS组。在实验结束时, 80AS组的增重率和体重与AS组无显著差异, HAS组体重显著低于AS组并与80AS组无显著差异,生长未能达到同期饱食水平。各组在实验结束时的肌肉粗脂肪和粗蛋白含量均随投喂水平降低而降低,性腺粗脂肪和粗蛋白则无显著差异,据此可以推测母本将营养优先供给性腺而非肌肉。实验末期AS组和80AS组卵直径无显著差异,均显著高于50AS组并低于HAS组,表明饥饿后恢复摄食对卵的发育有补偿效应。实验结束时各处理组的绝对繁殖力和相对繁殖力未受到投喂策略的显著影响。80AS、50AS及HAS组的star、sf-1、3β-hsd和cyp19a1基因表达由中期的显著低于AS组上调...     

摄食水平和投喂频率对大菱鲆幼鱼生长及生化成分的影响

以大菱鲆幼鱼(7.56±0.03 g)为试验对象,在水温17～19℃下,设计了4个摄食水平梯度(1.0％、1.5％、2.0％和饱食)和3个投喂频率梯度(1、2和3次·d-1),探讨了不同摄食水平和投喂频率对其生长及生化成分的影响.结果表明:随着摄食水平的升高,大菱鲆幼鱼的终末体重、相对增重率和摄食率显著升高(P＜0.05);特定生长率随摄食水平的增加呈线性升高;湿重、干重、蛋白质和能量转化效率出现先升高后降低的趋势;摄食水平对鱼体的体成分和组间表观消化率无显著影响(P＞0.05);不同投喂频率下,终末体重、相对增重率、特定生长率及转化效率呈先升高再降低的趋势,在2次·d-1时取得最大值;投喂频率对鱼体的体成分和组间表观消化率无显著影响(P＞O.05).     

西江鲤仔稚鱼生长及消化酶活性变化

为了探究了鲤(Cyprinus carpio)仔稚鱼的生长过程中主要消化酶活性变化规律, 实验测定了鲤从孵化出膜到40 日龄(日龄, Day after hatching)仔稚鱼期间的生长、可溶性蛋白含量和几种消化酶活性变化。结果显示: 仔稚鱼全长以及体重在15 日龄后增速加快, 特定生长率为14.81%。淀粉酶、脂肪酶、胰蛋白酶, 糜乳蛋白酶、碱性磷酸酶以及氨基肽酶在1 日龄仔鱼体内均能检测到活性。在仔稚鱼发育过程中, 其可溶性蛋白含量先下降后上升。仔鱼摄食前消化酶的活性出现一定的上升, 随着仔稚鱼消化系统发育以及营养方式的转变, 其消化酶活性从3到25 日龄处于不断的变化状态, 而25 日龄到实验结束鲤仔稚鱼的消化酶处于一种相对稳定的状态, 标志着其消化功能趋于完善。根据不同发育时期鲤消化酶活性的变化, 设计有机可腐化的材料制备人工鱼巢以提高人工鱼巢的生态修复功能, 降低饥饿对仔稚鱼成活率的影响。     

长薄鳅仔稚鱼发育和生长的研究

长薄鳅Leptobotia elongata(Bleeker)隶属鳅科、薄鳅属,分布在长江中上游江段及其支流,是鳅科鱼类中生长最快、个体最大的一种,最大个体达3.0kg。然而近20多年来,人为过度捕捞、生态环境破坏等原因,在长江中游已很难捕到此鱼,长江上游也正面临着生存环境的破坏而资源急速下降。       

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...     

长吻(鱼危)血细胞发生的研究

用Wright-Giemsa和PAS染色对长吻(鱼危)头肾、肾脏、脾脏、肝脏等器官组织的涂片、印片染色观察发现,头肾、肾脏和脾脏是其主要造血器官.红细胞、粒细胞和淋巴细胞主要在肾脏和头肾中发生,其次是脾脏.单核细胞则主要在肾脏和脾脏中发生,头肾中也有少量单核细胞产生.肝脏中无原始型血细胞,可能不是其造血器官.红细胞的发育经历四个阶段,其胞体体积经历了由大到小,由小到大再变小的"两大两小"发育过程;粒细胞的发育经历五个阶段,其胞体体积均由大变小,双叶或多叶核的粒细胞可能是衰老的粒细胞亦即核的分叶是粒细胞衰老的标志;淋巴细胞和单核细胞的发育各经历了三个阶段,两者发育成熟过程中胞体体积均由大变小.巨噬细胞由单核细胞发育而来.原血细胞和部分早期幼稚血细胞可以进行有丝分裂,部分成熟红细胞和血栓细胞可以进行直接分裂.红细胞在整个发育过程中,PAS反应均呈阴性,各类白细胞的发育过程中,PAS反应由阴性到阳性并逐渐增强,这显示随着白细胞的逐渐发育成熟,细胞内糖原物质含量逐渐增多.     

Isolation and characterization of 17 microsatellite loci for the Chinese longsnout catfish (Leiocassis longirostris)

We describe the isolation and development of 17 polymorphic dinucleotide microsatellite loci for the Chinese longsnout catfish (Leiocassis longirostris). All loci were polymorphic in the 30 individuals tested. The number of alleles per variable locus ranged from 6 to 18, with a mean of 11.71. Observed and expected heterozygosities ranged from 0.467 to 1.000 and from 0.540 to 0.929, respectively. Eight loci were found to have deviated from HWE in the sampled population after Bonferroni correction. Linkage disequilibrium tests revealed significant linkage between two loci (LLW5 and LL27). These microsatellite loci will be useful for revealing population structure, genetic diversity, and phylogeography of the Chinese longsnout catfish.     

Effect of dietary carbohydrate-to-lipid ratios on growth and feed utilization in Chinese longsnout catfish (Leiocassis longirostris Günther)

An 8‐week growth trial was carried out in a semi‐recirculation system at 26 ± 0.5°C to investigate the optimal dietary carbohydrate‐to‐lipid (CHO:L) ratio for carnivorous Chinese longsnout catfish (Leiocassis longirostris Günther). Triplicate tanks of fish were assigned to each of five isocaloric and isonitrogenous diets with different carbohydrate‐to‐lipid ratios (0.75, 1.48, 1.98, 2.99 and 5.07). The results showed that a higher specific growth rate (SGR) and feed rate (FR) were observed in the fish fed diet ratios of 1.98 CHO:L (P < 0.05). Overloading dietary carbohydrate (5.07 CHO:L ratio) caused skeletal malformations. Apparent digestibility of dry matter (ADC_d) significantly increased with dietary CHO:L ratio (P < 0.05), while significantly higher apparent digestibility of protein (ADC_p) and apparent digestibility of energy (ACD_e) was observed only in the 1.98 CHO:L group (P < 0.05). Whole body contents of dry matter, lipid and energy significantly increased as the CHO:L ratio decreased (P < 0.05). The hepatosomatic index (HSI) was highest at 1.98 CHO:L ratio (P < 0.05). Highest dietary CHO:L ratio resulted in lower liver glycogen, liver lipid, plasma glucose and plasma triacylglycerol (P < 0.05), whereas there was no significant difference in plasma total cholesterol (P > 0.05). High dietary CHO:L ratio caused pathological changes in fish morphology and liver histology. Based on maximum growth, the optimal carbohydrate‐to‐lipid ratio was 1.98 for Chinese longsnout catfish.     

Temporal genetic variation of the Chinese longsnout catfish (Leiocassis longirostris) in the upper Yangtze River with resource decline

Environmental Biology of Fishes - We investigated the temporal dynamics of population genetics of the Chinese longsnout catfish (Leiocassis longirostris) given wild population decline due to...     

Genetic variation of the Chinese longsnout catfish Leiocassis longirostris in the Yangtze River revealed using mitochondrial DNA cytochrome b sequences

The mitochondrial DNA cytochrome b of 132 Leiocassis longirostris collected from 12 localities in the upper to lower reaches of the Yangtze River were amplified and partially sequenced using the PCR technique. The results showed that 27 nucleotide sites were variable along 817 bp length of homologous sequence (3.3%), base substitutions happened mostly at the third codon position. A total of 22 haplotypes were identified, which were characterized with moderate haplotype diversity (h = 0.5417 ± 0.0519), but low nucleotide diversity (π = 0.0019 ± 0.0012). Median-joining network analysis revealed star-shaped patterns with one common central haplotype (H3), whereas mismatch distribution analysis found that the Chinese longsnout catfish fitted a smooth unimodal distribution, which suggested that this species underwent population expansion following bottlenecks and/or they originated from a small number of founding individuals. The time that the total population of Chinese longsnout catfish in the Yangtze River expanded was estimated 169,000–337,000 years before present. The analysis of molecular variance (AMOVA) and phylogenetic reconstructions did not detect significant geographic structure between different river sections, especially between above and below the Gezhouba Dam and the Three Gorges Dam, which suggested that these recently developed dams might have not significantly resulted in population genetic differentiation in the Chinese longsnout catfish.     

Genetic variation at mtDNA and microsatellite loci in Chinese longsnout catfish (<Emphasis Type="Italic">Leiocassis longirostris</Emphasis>)

Genetic variability and population structure of the Chinese longsnout catfish Leiocassis longirostris Günther in the Yangtze River was examined with mitochondrial control region sequences and nuclear microsatellite markers. A 705-bp segment of the mitochondrial DNA control region was sequenced from 132 samples, which identified a total of 61 haplotypes. The Chinese longsnout catfish in the Yangtze River was characterized with high haplotype diversity (h = 0.9770 ± 0.0041) but low nucleotide diversity (π = 0.0081 ± 0.0043). Median-joining network analysis revealed a star-shaped pattern and mismatch distribution analysis found a smooth unimodal distribution, which suggested that this species in the Yangtze River underwent a population expansion following bottlenecks and/or they originated from a small size of founding population. It was estimated that the possible time of population expansion was 139,000–435,000 years before present, a time period in the middle Pleistocene. The analysis of molecular variance and phylogenetic reconstructions did not detect significant geographic structure between different river sections. This pattern of genetic variation was further evidenced with nuclear microsatellite markers. The genetic differentiation between above and below the Gezhouba Dam and Three Gorges Dam is very small at mitochondrial and nuclear levels, which suggested that these recently developed dams might have not significantly resulted in population genetic fragmentation in the Chinese longsnout catfish. However, the potential exacerbation of genetic structuring by the dams should not be overlooked in the future.     

Effects of salinity on growth and survival of African sharptooth catfish (clarias gariepinus) larvae

Growth and survival of replicate batches of African sharptooth catfish (Clarias gariepinus) larvae were monitored in 0, 2.5, 5.0, 7.5 and 10 ppt salinity. No significant differences in mortality or growth rate were evident between 0 and 5 ppt salinity. At 7.5 ppt mortality rate was higher and larval growth rate declined in comparison to the lower salinities. At 10 ppt all larvae died within 48 hours. The condition factor of the larvae similar between 0–2.5 ppt and displayed a declining trend between 2.5–7.5 ppt. Osmoconcentratkm of blood plasma of C. gariepinus in fresh water was 280 ± 20 mOsm/kg which is equivalent to 9.5 ppt salinity. It was concluded that 0–2.5 ppt is the optimal sclinity range for larval rearing and that short-term exposure to higher salinities (2.5–7.5 ppt) could be effective in the treatment of ectoparasitic diseases.     

Effects of feeding rate on the growth performance of gynogenetic albino sterlet,Acipenser ruthenus (Linnaeus, 1758) larvae

The feeding rate effects were studied on the growth performance of gynogenetic diploid larvae of sterlet Acipenser ruthenus during the first 4 weeks of exogenous feeding. The experimental rearing was conducted from 7 to 38 days post‐hatch (dph) in a circulation system. This was set up in four groups with three replicates (440 individuals/replicate), viz: AC‐control larvae fed Artemia sp., CFC‐control larvae fed compound feed, AG‐gynogenetic larvae fed Artemia sp., and CFG‐gynogenetic larvae fed compound feed. The larvae were reared in glass tanks (44 L volume, 10 individuals/L) with the temperature maintained at 18 ± 0.5°C, photoperiod of 12L:12D and water flow regime of 1‐L/min and fed 50%, 25%, 25%, and 9% of their total biomass/day during feeding. Highest TL and WBW of gynogenetic diploid larvae (AG) were observed with 50.6 ± 1.2 mm and 607.3 ± 36.1 mg (n = 30) at 38 dph. Highest TL and WBW of control larvae (AC) were recorded with 49.5 ± 3.8 mm and 600.8 ± 88.0 mg (n = 30), respectively, with 73.1% ± 11.4% survival; the lowest survival rate was at 46.4% ± 7.1% (n = 30) for the CFG group. The results indicate that the gynogenetic and normal larvae of sterlet fed with live food (Artemia nauplii) from 7 dph can achieve higher growth and survivability compared to the larvae fed with formulated test feed. Results of this study suggest that the effective rearing of sterlet larvae from 7 to 38 dph strongly depends upon the types of feed rather than the genome manipulation performed.     

延迟首次投喂对南方鲇(Silurus meridionalis Chen)仔鱼身体含能量、体长及游泳能力的影响

在（22.0±0.5）℃条件下,将人工孵化的南方鲇仔鱼分别于出膜后4、5、6、7天进行首次投喂（其中4d的为对照组）,首次投喂前（出膜后4d）取样测量体长、体重、身体含能量作为初始值,于出膜后7d（延迟投喂实验）和21d（继续喂养实验）分别测定体长、体重、身体所含能量和临界游泳速度。结果显示：延迟投喂实验结束时各处理组的体重、身体含能量和体长随首次投喂时间的延迟均呈下降趋势,相对临界游泳速度随首次投喂时间的延迟表现为先提高后降低的趋势,绝对临界游泳速度在延迟投喂2d以内无显著差异;继续喂养实验结束时处理组各指标逐渐接近对照组水平,两种临界游泳速度表现为同步变化趋势;另外,体长特定生长率相对百分比（SGRL%）的变化幅度小于身体含能量特定生长率相对百分比（SGRE%）的变化幅度,而绝对临界游泳速度相对百分比（Ucrit%）的变化又小于体长特定生长率相对百分比的变化。结果表明：早期食物资源的短缺会导致南方鲇仔鱼体重、身体含能量产生明显变化,体长生长速度的变化则相对较小,而短期饥饿不会显著降低南方鲇仔鱼的游泳能力。     

Effects of elevated CO2 on feeding preference and performance of the gypsy moth (Lymantria dispar) larvae

Multiple‐choice assays were conducted in the laboratory to examine the effect of CO₂‐induced changes in leaf quality on growth, nutritional indices and preferences of the gypsy moth (Lymantria dispar) larvae. The tested tree species, one‐year‐old aspen (Populus pseudo‐simonii Kitag.), two‐year‐old birch (Betula platyphylla) and three‐year‐old oak (Quercus mongolica Fisch.) were transplanted to open‐top chambers at ambient or elevated CO₂ (650 ppm) concentrations in May 2005. The present study was conducted in 2006. Leaves from the upper and lower crowns of each tree species were sampled and analysed, respectively. On both measurement dates (24 July 2006 and 16 August 2006), there were significant CO₂ effects on levels of condensed tannin, starch, nitrogen and C : N ratio. But only on the latter date, were the concentrations of total phenolics, soluble sugar, carbon and total non‐structural carbohydrates significantly affected by elevated CO₂. Leaf dry weight content and specific leaf weight were almost completely unaffected by CO₂ enrichment. Gypsy moth larvae exhibited a clear selectivity for tested leaf types (leaves from the upper and lower crowns of each tree species) even in their early instar stage, with the upper leaves of P. pseudo‐simonii being the most preferable and the lower leaves of Q. mongolica being the least preferred. The changes in leaf quality significantly reduced larval growth and altered partial indices of insect performance (e.g., relative growth rate and relative consumption rate). However, at least in this short‐term choice feeding assay (13 days), the CO₂‐induced changes in leaf quality had no significant effects on food preference behaviour of the gypsy moth larvae, neither within the limited range of host plants nor within the leaves at different canopy heights of the same tree species.     

The complete mitochondrial genome of the Chinese longsnout catfish <Emphasis Type="Italic">Leiocassis longirostris</Emphasis> (Siluriformes: Bagridae) and a time-calibrated phylogeny of ostariophysan fishes

The complete mitogenome sequence of the Chinese longsnout catfish Leiocassis longirostris was determined using long-polymerase chain reaction (long-PCR) and directly sequenced with primer walking method. The complete mtDNA was 16,534 bp in length and contained 13 protein-coding genes, two rRNA genes, 22 tRNA genes, and a control region (D-loop), the gene composition/order of which was identical to that observed in most other vertebrates. Phylogenetic relationship of 15 ostariophysan fishes was reconstructed using Bayesian inference and maximum likelihood methods based on a total of 15,658 nucleotides from all the 13 protein-coding, two rRNA, and 22 tRNA genes, using recently developed models of rate autocorrelation, which resolved the phylogenetic relationship of the major ostariophysan lineages with a high statistical support. The present result was consistent with some previous molecular cladistic work which supported the grouping of (((((Characiformes, Gymnotiformes), Siluriformes), Cypriniformes), Gonorynchiformes), outgroup). The Chinese longsnout catfish together with the Bagrid catfish (both from the same family Bagridae) had a closer affinity with Amblycipitidae than with other four analyzed catfish families. The relaxed molecular clock method incorporated into the program BEAST vl.5.3 was used to estimate divergence dates among ostariophysan lineages, which revealed that the major ostariophysan lineages diversified in the middle Jurassic (around 164.5 million years ago (Mya)) and the split of Leiocassis/Pseudobagrus occurred in the Oligocene to Miocene (8.9–25.1 Mya). The time-calibrated tree generated in this study would provide a powerful evolutionary tool for broad-scale comparative studies of the catfishes and the ostariophysan fishes.