南方鲇幼鱼细菌性败血症病原与组织病理

从天然患病南方鲇(Silurus meridionalis Chen)幼鱼的肝脏中分离获得1株优势菌,命名为SCL1.用该菌株人工感染健康南方鲇幼鱼,发现菌株SCL1的感染致死率高,且患病症状与自然发病症状一致.再从人工感染的患病鱼肝脏中分离病原菌,再次感染健康南方鲇幼鱼,其症状与自然发病症状一致,确认分离菌株为南方鲇"败血症"的致病菌.该菌株形态学、生理生化特征和16S rDNA基因序列显示其为嗜水气单胞菌(Aeromonas hydrophila).药敏试验结果表明,该菌对土霉素、链霉素、氧氟沙星、氟哌酸、卡那霉素和庆大霉素高度敏感,而对青霉素钠、麦迪霉素、罗红霉素、甲氧苄啶、乙酞螺旋霉素不敏感.组织病理研究显示患病南方贴肝组织严重坏死,肝细胞排列紊乱,部分肝细胞核肿胀、崩解;脾脏细胞间界限不清,细胞核膨大,核内染色质疏松;肾小管上皮细胞肿胀,肾小囊腔间隙增大,可见该菌主要损伤南方鲇幼鱼肝、肾和脾.本研究旨在为南方站细菌性败血症的诊断与防治提供科学依据.     

Effect of dietary composition on specific dynamic action in southern catfish Silurus meridionalis Chen

The effect of dietary macronutrient composition on specific dynamic action (SDA) in southern catfish Silurus meridionalis Chen juveniles (39.0±2.8 g) was studied. A control diet (40% protein, 10% lipid and 15% carbohydrate) was the optimal dietary profile for growth in this catfish according to a previous study. Based on this, two diets were formulated by substituting protein and lipid for one another, referred to as LPHL (30% P:15% L) and HPLL (50% P:5% L), and two diets were formulated by substituting protein and carbohydrate for one another, referred to as LPHC (30% P:30% C) and HPLC (50% P:0% C). The results showed that dietary composition affected the peak metabolic rate, duration and SDA coefficient. The peak metabolic rate in the LPHC group (211.5 mgO₂ kg^?1 h^?1) was significantly lower than catfish in the control (265.2 mg O₂ kg^?1 h^?1) and the HPLC (257.7 mg O₂ kg^?1 h^?1) group. The SDA duration in the control group (26.8 h) was significantly shorter than those of the HPLL (38.0 h), LPHC (33.8 h) and HPLC (33.8 h) groups. The SDA coefficient in the LPHL group (11.1%) was significantly lower than those of the control and the other groups (13.2–15.4%). The results suggest that in southern catfish, the SDA response to dietary carbohydrate is similar to that of dietary protein, and that the SDA may not be affected solely by an increase in the amount of protein ingested, but may be influenced by interaction of other dietary components.     

脂肪酶对南方鲇生长性能、消化酶活性及血液生化指标的影响

在基础饲料中分别添加0、0.1、0.3 g/kg的脂肪酶,饲喂平均体重(57.6±0.02)g的南方鲇(Silurus meridionalis Chen)60 d,测定南方鲇的生长性能、饲料表观消化率、消化酶活性及血液生化指标。结果显示:添加0.1 g/kg和0.3 g/kg的脂肪酶,增重率比对照组分别提高了4.0%和5.8%,但差异不显著(P>0.05),饲料系数分别下降了5.0%和6.6%,差异显著(P<0.05),肥满度和粗脂肪消化率显著提高(P<0.05),对内脏指数、肝脏指数、肠脂指数、胰蛋白酶活力、肠蛋白酶活力、肠脂肪酶活力及血液生化指标均没有显著影响(P>0.05)。添加0.3 g/kg的脂肪酶显著提高胰脂肪酶活力(P<0.05),添加0.1 g/kg的脂肪酶对胰脂肪酶活力没有显著影响(P>0.05)。结果表明,在脂肪水平为10%的饲料中添加0.3 g/kg的脂肪酶可以提高胰脂肪酶活力,提高脂肪消化率,改善饲料利用率。     

不同摄食状态下南方鲇幼鱼肠道黏液细胞的量化分析

量化分析了南方鲇(Silurus meridionalis)幼鱼在正常摄食节律下摄食前(S0d)、摄食后64 h(S0d-64h)、饥饿16d(S16d)、饥饿32 d(S32d)以及饥饿后首次恢复摄食64 h(S16d-64h,S32d-64h)肠道各类型黏液细胞的反应特征。结果发现,摄食后肠道各部位黏液细胞总数均有一定程度减少,其中前肠减少最为显著(P<0.05);中肠和后肠II型黏液细胞数量显著减少(P<0.05),中肠的III型黏液细胞数量显著增多(P<0.05);肠腔中黏液增多,黏液细胞呈空泡结构。S16d组和S16d-64h组前肠和中肠的I型细胞数量显著减少(P<0.05),III型细胞数量显著增多(P<0.05)。S32d组和S32d-64h组前肠各类型细胞数量以及黏液细胞总数变化不明显(P>0.05);中肠的II型细胞数量显著增多(P<0.05),IV型细胞数量显著减少(P<0.05);饥饿和恢复摄食后肠各类型黏液细胞数目变化不明显(P>0.05)。研究表明,南方鲇幼鱼肠道黏液细胞的摄食反应明显;饥饿胁迫以及恢复摄食后肠道黏液细胞的反应特征与肠道各段的生理功能相适应;面对营养胁迫时,肠道前段能迅速调节黏液细胞的数目,而后肠基本不变,可能是该鱼应对营养缺乏的保护性适应机制。     

鲶鱼养殖技术之二龟石水库网箱养殖南方大口鲶技术

南方大口鲶俗称河鲶,是一种经济价值较高的淡水鱼类,肉食性,主要摄食小鱼、小虾,养殖经济效益高,市场开发前景广阔。位于广西区贺州市富川县的龟石水库,库区面积约6万亩,水质清新且无污染,库区内各种野杂鱼品     

小型水库养殖南方大口鲶高产高效技术

在小型水库中主养南方大口鲶,投放经转食驯化的大规格鱼种,用浮性颗粒饲料养殖166 d,成鱼增重14.7倍,平均规格739 g/尾,产量6 453.4 kg/hm2,利润42 593元/hm2。与施肥主养鲢、鳙相比,单产提高1.29%,利润增长3.65倍,实现了品种结构调整和高产、高效的目标。     

南方鲇幼鱼标准代谢的昼夜节律

为了考察南方鲇标准代谢的昼夜节律,在光照周期13 L∶11 D、水温25℃的条件下,于14:00、16:00、18:00、20:00、22:00、00:00、2:00、4:00、6:00、8:00、10:00、12:00分别测定南方鲇幼鱼[(17.36±0.46)g,n=12]的标准代谢率。试验结果表明:南方鲇幼鱼标准代谢的峰值[(109.86±5.02)mgO2/(kg.h)]和最小值[(86.6±5.42)mg O2/(kg.h)]分别出现在22:00、12:00;标准代谢率的日平均、夜间平均、白昼平均值分别为(95.88±2.02)、(101.78±6.44)、(91.67±3.49)mg O2/(kg.h);夜间与白昼的平均标准代谢率差异显著(P<0.05)。南方鲇的夜间标准代谢显著高于白昼;在近自然光照周期条件下日平均标准代谢率低于相关文献报道的在全光照条件下的研究结果。     

鲶鱼养殖技术之三:南方大口鲶池塘苗种培育技术

南方大口鲶(Silurusmeridionalis Chen)属鲶形目、鲶科,俗称鲶巴朗,原产于长江及其支流和通江湖泊,是一种大型肉食性鱼类。为了提高该鱼在福建省的养殖产量,减少运输环节,节约成本,我们于2003年进行了南方大口鲶池塘苗种培育试验,现将其技术总结如下:一、池塘条件池塘面积约4亩,养殖期间平均水深1.5m,水温17℃~31℃,水色呈浅绿色,水体透明度30cm~45cm,pH6.8~8.1,使用前泼洒生石灰水进行全池消毒,7天后注水。二、鱼苗放养2003年5月17日运回鱼苗2万尾,平均全长为2.1cm/尾,体重0.16g/尾,运输成活率为90%,暂养24小时后放入池塘。三、养殖管理1…     

南方大口鲶鱼病防治技术

<正> 南方大口鲶以其生长快、产量高、质优效益好而成为水产养殖优良品种之一。它抗病力强,在天然条件下生长增殖和人工粗养情况下,一般不会患病,但在高密度精养过程中,也会发生鱼病。笔者根据有关资料和养殖大口鲶防治实践,现将南方大口鲶几种常见病的防治方法介绍如下,供养殖户参考。1 病毒性出血病 病症及危害:病鱼的上下颌、口腔、眼眶、鳃盖充血,眼球突出,鳃丝、鳍梢腐烂,体表及     

Establishment and characterization of an ovarian cell line from Southern catfish (Silurus meridionalis)

An ovarian cell line was successfully developed from the juvenile ovary of Southern catfish (SCO1) (Silurus meridionalis), which was designated as SCO1. The cell line multiplied preferentially in L-15 medium with 15 % fetal bovine serum at 28 °C for more than 70 passages over a period of 420 days. SCO1 showed fibroblast-like morphology and predominantly retained a diploid karyotype of 58 chromosomes. From the gene expression patterns, SCO1 showed a characteristic of ovarian granulosa cells. After the cells were transfected with the green fluorescent protein expression vector, bright fluorescent signals could be observed in approximately 30 % cells. This cell line may be valuable for the evaluation of endocrine disruptors and studying interactions between somatic cells and germ cells.     

氨氮对南方鲶两种抗氧化酶和抗菌活力的影响

采用静水生物试验法,人工添加氨氮并检测与南方鲶免疫相关的两种抗氧化酶及抗菌活力的变 化,进行氨氮对南方鲶免疫水平影响的试验。结果表明：在本试验剂量范围内,氨氮在一定浓度时对南方鲶 超氧化物歧化酶(SOD)、过氧化物酶(POD)以及抗菌活力均表现出诱导作用;在氨氮浓度高于30 mg/L 时 各组 SOD 及 POD 活力均出现显著高于正常水平(P＜0． 05) 的活力值,之后随时间延长活力逐渐下降;高浓 度氨氮水平(150 mg/L与120 mg/L)对抗菌活力主要表现为抑制作用。试验表明氨氮对南方鲶存在一定的 “阈值”,只有水体实际氨氮浓度超过这一作用“阈值”(30～60 mg/L 之间)时才会表现出诱导作用。     

不同配合饲料对南方鲇幼鱼体组成的影响

主要探索不同饲料组成对鱼体组成的影响.将360尾南方鲇(Silurus meridionalis Chen)幼鱼随机分成24组,饲养于24个水泥池中;共设计了21种饲料;实验持续了40 d.结果表明:(1)不同营养素水平,对鱼体中的蛋白质沉积无明显影响;肌肉中脂肪水平随着饲料中脂肪和碳水化合物(CBH)水平的增加而增加;CBH含量为33%时,肌肉中的CBH的沉积量显著高于其他几个组(P<0.05);(2)脏体比和肠脂比随着饲料中脂肪水平升高而升高,脂肪水平9%～15%,肝脏中沉积的脂肪含量随着饲料中脂肪含量的增加而增加,添加CBH含量为33%的饲料时,肝脏中糖原的沉积含量显著的高丁其他几个CBH含量的组(P<0.05).     

鲇仔、稚鱼消化系统胚后发育的组织学观察研究

通过石蜡包埋切片法对鲇(SilurusasotusL.)仔、稚鱼消化系统胚后发育进行了较系统的组织切片观察。本研究描述了全长5.0～22.5mm的鲇摄食器官、消化器官胚后发育的组织学结构特征。观察发现,1～3日龄为内源性营养阶段,卵黄囊很大,2日龄消化道出现裂缝状腔隙,3日龄基本贯通但未开始摄食;4～6日龄为混合营养阶段,卵黄囊被逐步吸收,主要靠吞食轮虫、小型枝角类等为食;6日龄以后卵黄囊消失,进入外源性营养阶段,捕食能力增强。观察还发现,鲇前咽顶壁始终平直无粘膜皱褶;颌齿和咽齿为斜生尖锥状的同型齿,数量多、排列紧密,与相应的骨骼牢固地骨性固着;后咽、食道的粘膜上皮内粘液细胞极多,深层结缔组织肌肉层发达。这些构造适应于鲇的完全吞食摄食方式。胃腔小,前肠膨大、中肠粘膜上皮细胞纹状缘发达,肝脏和胰脏发育速度较快。胃的消化功能较弱,主要储存、消化场所为前肠,吸收场所在中肠。鱼苗4～6日龄下塘适宜,6～8日龄可开始诱其摄食人工饲料。     

长江中上游南方鲇遗传多样性的RAPD分析

采用随机扩增多态性DNA(RAPD)技术对取自长江中上游合川、木洞、涪陵、彭水、巫山、宜昌及岳阳7个江段的南方鲇(Silurus meridionalisChen)野生群体的遗传多样性进行了分析,24个随机引物共检测出327个位点(200~2500 bp)。各群体的多态位点比例在28.75%~48.62%之间,基因多样性指数为0.2047~0.3074。遗传距离显示长江中上游南方鲇各群体间有一定遗传分化,其中,木洞和合川群体间遗传距离最小为0.0537),而合川和岳阳群体间的遗传距离最大(0.1205),群体间遗传分化系数为0.1866。聚类分析(UPGMA)显示,7个群体聚为两大类群,合川和木洞亲缘关系最近,首先聚在一起,之后与彭水、涪陵、巫山群体相继聚类形成类群Ⅰ,岳阳和宜昌群体则聚类形成类群Ⅱ。Shannon指数分析表明,长江中上游南方鲇野生群体间种质资源状况良好,遗传多样性水平较高。     

Effect of temperature on excess post-exercise oxygen consumption in juvenile southern catfish (<Emphasis Type="Italic">Silurus meridionalis</Emphasis> Chen) following exhaustive exercise

The effects of temperature on resting oxygen consumption rate (MO_2rest) and excess post-exercise oxygen consumption (EPOC) after exhaustive exercise (chasing) were measured in juvenile southern catfish (Silurus meridionalis) (8.40 ± 0.30 g, n = 40) to test whether temperature has a significant influence on MO_2rest, maximum post-exercise oxygen consumption rate (MO_2peak) and EPOC and to investigate how metabolic scope (MS: MO_2peak − MO_2rest) varies with acclimation temperature. The MO_2rest increased from 64.7 (10°C) to 160.3 mg O₂ h⁻¹ kg⁻¹ (25°C) (P < 0.05) and reached a plateau between 25 and 30°C. The post-exercise MO₂ in all temperature groups increased immediately to the peak values and then decreased slowly to a steady state that was higher than the pre-exercise MO₂. The MO_2peak did not significantly differ among the 20, 25 and 30°C groups, though these values were much higher than those of the lower temperature groups (10 and 15°C) (P < 0.05). The duration of EPOC varied from 32.9 min at 10°C to 345 min at 20°C, depending on the acclimation temperatures. The MS values of the lower temperature groups (10 and 15°C) were significantly smaller than those of the higher temperature groups (20, 25 and 30°C) (P < 0.05). The magnitude of EPOC varied ninefold among all of the temperature groups and was the largest for the 20°C temperature group (about 422.4 mg O₂ kg⁻¹). These results suggested that (1) the acclimation temperature had a significant effect on maintenance metabolism (as indicated by MO_2rest) and the post-exercise metabolic recovery process (as indicated by MO_2peak, duration and magnitude of EPOC), and (2) the change of the MS as a function of acclimation temperature in juvenile southern catfish might be related to their high degree of physiological flexibility, which allows them to adapt to changes in environmental conditions in their habitat in the Yangtze River and the Jialing River.     

灭活菌苗免疫的南方鲇外周血液细胞免疫指标的变化

以嗜水气单胞菌(Aeromonashydrophila)灭活菌苗为免疫原,以平均体重为86 20g人工饲养的健康南方(Silu rusmeridionalis)为实验对象,通过腹腔注射免疫原(浓度为1 0×108/mL)免疫,剂量为0 2mL/尾,并分别在免疫后的第1、2、4、7、14、21、28天对实验鱼尾静脉采血,进行血液生理指标和血液中吞噬细胞活性的测定。结果显示,嗜水气单胞菌灭活菌苗(FKC)可以增加南方外周血液白细胞数量并引起不同种类白细胞组成比例的变化,提高吞噬细胞的吞噬活性。在免疫后第1、2、4、7、14、21、28天,南方外周血中白细胞数量呈明显上升趋势,其中嗜中性粒细胞、单核细胞、淋巴细胞变化趋势更为明显;而且吞噬细胞活性大为提高,吞噬百分比较对照组平均升高了17 66%,吞噬指数比对照组平均升高了1 16,在免疫后第4天吞噬百分比和吞噬指数均达到最高值,吞噬百分比为48 40%,吞噬指数为4 82;免疫后第21天,吞噬百分比和吞噬指数开始下降,但仍高于对照组。由此表明,使用疫苗后,鱼类非特异细胞免疫在初期(尤其是在第2～7天)明显增强,这是鱼用疫苗在免疫早期保护作用的主要机制之一。     

Isolation and Characterization of Edwardsiella ictaluri from Southern Catfish,Silurus soldatovi meridionalis, (Chen) Cultured in China

In April 2011, there was an outbreak of an infectious disease in southern catfish, Silurus soldatovi meridionalis, (Chen) (15–20 g) in Sichuan Province, China. Two isolates, LW101 and LW102, were isolated from kidney and liver of the sick fish on brain‐heart infusion (BHI) agar and were considered to be the cause of this disease based on experimental challenges. The morphological and physiological characteristics as well as the biochemical tests of the two isolates were the same and similar to Edwardsiella ictaluri. Furthermore, the sequencing of the 16S rRNA gene and the gryB gene revealed that the isolates were highly homogeneous with E. ictaluri. On the basis of the phenotypic characteristics and phylogenetic analysis of these genes, both isolates were identified as E. ictaluri. Susceptibility of the isolates to 22 antibiotics was tested using the disc diffusion method. Both isolates showed a similar antibiotic susceptibility, which was characterized by resistance to acetylspiramycin, ampicillin, clarithromycin, penicillin, oxytetracycline, and sinomin (SMZ/TMP); the strains were susceptible to amikacin, chloramphenicol, florfenicol, roxithromycin, ciprofloxacin, norfloxacin, doxycycline, and tenemycin. To our knowledge, this is the first report of E. ictaluri infection in southern catfish.     

Isolation, sequence analysis, and characterization of androgen receptor in Southern catfish, Silurus meridionalis

Androgen receptor (AR), the mediator of androgen, plays important roles in the androgen signal pathway. In the present study, we isolated and analyzed the cDNA sequence and tissue distribution of androgen receptor in Southern catfish (scAR). The full-length cDNA of scAR contains 3,116 bp with an open reading frame (ORF) of 2,415 bp, encoding a protein of 804 amino acids (aa). Tissue distribution analysis of scAR revealed that it was expressed in all tissues examined, with no sexual dimorphism in the ovary and testis. Phylogenetic analysis and multiple amino acids sequence alignment indicated the close relationship and high similarity of scAR with ARs from cypriniform species. In addition, partial sequences of ARs from 7 other siluriform species were also isolated. Comparison of catfish ARs with those from other vertebrates revealed that an extra C-terminal tail of about 20aa exists in all the ARs from siluriform fishes investigated, but not in other ARs. The extra sequence was resulted from a 4-bp insertion before the stop codon of other vertebrate ARs, and it was identical in ARs from siluriform species of the same genus but different among ARs from species of different genera. We report here for the first time that the ARs from siluriform species are longer in C-terminal than those from other vertebrates and it might be useful in reconstruction of the phylogenetic relationship among siluriform fishes. The significance of the extra C-terminal tail for AR function remains elusive.     

饥饿对南方鲇幼鱼胃排空及其数学模型选择的影响

为研究饥饿对南方鲇幼鱼胃排空及其数学模型选择产生的影响,实验在(25±0.5)℃条件下,在对照组(饥饿0 d,S0)和饥饿组(饥饿16 d,S16;饥饿32 d,S32)实验鱼摄入6%BW(百分比体质量)泥鳅饵料后的不同时间分别测定胃内容物重量及其百分比,用常见3个数学模型对实验数据进行拟合并比较。结果发现,随摄食后时间的增加,3个实验组的胃内容物重量及其百分比均呈现阶段性减少变化特征,但饥饿组(S16,S32)胃内容物重量百分比的下降速率明显慢于S0对照组(P<0.05);S0对照组和饥饿组(S16,S32)胃排空的最优数学模型均为平方根模型;S32饥饿组的胃排空率(0.188%/h)明显小于S0对照组(0.239%/h)(P<0.05),两个饥饿组的胃排空时间(均为64 h)显著长于S0对照组(36 h),二者都延长了近78%。研究表明,饥饿对南方鲇幼鱼的胃排空特征及其最优数学模型未产生显著影响,但明显降低该种鱼的胃排空率并延长胃排空时间。