Life cycle of Caligus rogercresseyi, (Copepoda: Caligidae) parasite of Chilean reared salmonids

Caligus rogercresseyi, [Contrib. Zool. 69 (2000) 137] is the only caligid known to affect the salmon industry in Southern Chile. Economic losses due to reduced fish quality, cost of chemical treatment and outbreaks of other diseases such as the Piscirickettsiosis occur. The life cycle of C. rogercresseyi is described in rainbow trout reared in seawater tanks from observations made under natural conditions of light and temperature between January 1997 and April 1998. Fish were infected with laboratory-cultured larvae obtained from ovigerous females. Rainbow trout were periodically slaughtered for parasite collection and identification. C. rogercresseyi life cycle includes the following stages: two nauplius, one copepodid, four chalimus and the adult. No preadult stage was observed. Timing of the different stages of development was directly dependent on water temperature. The maturation of the eggs or the time for a complete life cycle took place at 45 days in July at 10.3 °C, 31–32 days in April at 12.4 and 12.8 °C, respectively, and at 26 days in November at 15.2 °C. In January, at 16.7 °C, only the appearance of first eggs were observed at 18 days. A simple degree–day (dd) model is proposed for each developmental stage between 4 and 17 °C, where the development rate is a linear function of the average temperature of water. Using this degree–day model, the proportion of fourth stage chalimus was maximum at 172 dd of effective temperature, adult males at 193 degree–days, adult females at 208 dd. The minimum temperature threshold is at 4.2 °C where there is no development of the parasite. The appearance of first eggs occurred at 231 dd and the first pigmented eggs at 277 dd. The temperature-independent degree–days value allowed to predict the timing of C. rogercresseyi life cycle at any temperature within the evaluated range.     

基于转录组测序技术筛选花(鱼骨)卵巢发育相关基因

为筛选影响花■卵巢发育相关的基因,采用Illumina Hiseq技术对花■脑、卵巢和肝脏组织进行高通量转录组测序。结果显示,3个组织分别产生了49 484 132、47 540 538和50 622 304个clean reads,组装后共获得了99 878个unigenes,平均长度为1 430 bp。DE seq分析发现,在脑vs.卵巢组中特异性表达的基因数为2 305个,脑vs.肝脏组中特异性表达的基因数为839个,卵巢vs.肝脏组中特异性表达的基因数为1 474个,3个比较组共有的差异表达基因数为860个。GO分析发现,上述差异表达基因主要集中在初级代谢过程(primary metabolic process)、单细胞过程(single-organism process)、有机物代谢过程(organic substance metabolic process)等生物学过程中。KEGG pathway分析显示,一些与卵巢发育和减数分裂相关的信号通路得到了显著富集,如GnRH信号通路、类固醇激素合成、TGF-β信号通路、卵母细胞减数分裂等代谢通路。本研究结果丰富了花■的基因资源,可为花■的繁殖生物学研究提供基础数据。     

花鲈ncc、nkcc基因在海、淡水适应中鳃组织的表达与定位分析

为探究ncc、nkcc基因在花鲈渗透调节中发挥的作用,实验通过全基因组鉴定、多重序列比对、系统进化树构建以及蛋白结构预测对花鲈ncc进行了鉴定及序列分析,利用实时荧光定量PCR (qRT-PCR)检测ncc和nkcc在海水、淡水花鲈鳃组织中的表达水平,利用原位杂交技术确定ncc2和nkcc1a在海水及淡水花鲈鳃中的表达位置。结果显示,从花鲈中鉴定出2个ncc基因,即ncc1和ncc2,其编码序列(CDS)长度分别为2 691和3 120bp,编码896和1 039个氨基酸,在进化上具有保守性。ncc2在淡水花鲈鳃组织中的表达量显著高于海水,而nkcc1a在海水花鲈鳃组织中的表达量显著高于淡水,ncc1、nkcc1b、nkcc2在海淡水中的表达量则无显著差异。淡水适应过程中花鲈鳃组织中的ncc2的表达量逐渐上调,而nkcc1a的表达量逐渐下调;海水适应过程则呈现相反的表达趋势。此外,原位杂交结果显示,ncc2和nkcc1a基因分别位于淡水与海水中鳃组织的相邻鳃小片间的鳃丝上皮。以上结果表明,ncc2和nkcc1a基因分别编码淡水及海水花鲈鳃中重要的Na⁺及Cl     

盐度与pH对花鲈孵化、初孵仔鱼成活及早期幼鱼生长性能的影响

为探究我国北方海域花鲈繁育适宜盐度和pH处理的设定,及促进早期花鲈苗种推广,本研究针对不同盐度(0、15、20、25、30、35和40)与pH(5.5、6.5、7.5、8.5和9.5)条件下,北方人工繁殖花鲈受精卵的孵化率、畸形率及饥饿10 d后的存活情况进行了分析,并对花鲈初孵仔鱼进行不投饵耐饥饿实验,记录每日存活率(SR)及最终生存活力指数(SAI)。最后观测低盐0、养殖盐度30与高盐45对花鲈早期幼鱼生长性能的影响。结果显示,北方海域花鲈受精卵适宜孵化盐度为20~35,以盐度25组孵化率最高,适宜pH为6.5~7.5,以pH 6.5组孵化率最高。低盐15组中,具最低的孵化率及最高的畸形率,但在最终饥饿SR的统计中,低盐15组的SR及SAI明显高于盐度30与35组,推测低盐15接近花鲈体液等渗点,降低了渗透调节中的能量消耗,更利于存活。初孵仔鱼饥饿实验中,盐度20组SR下降相对平缓,在第8天仍有12.66%的SR(其他组已为0)。饥饿1 d时,各pH组SR均小于90%,以pH 6.5组SR最高,为89.11%。与盐度处理组相比,花鲈初孵仔鱼对pH变化较为敏感,其孵化率及最终SR显著低于盐度处理组。花鲈早期幼鱼盐度处理组中,低盐0与高盐45将对此规格花鲈幼鱼产生较大损伤,以高盐45抑制最显著,应为苗种盐度推广的上限,而花鲈生长盐度30与各处理盐度相比,较适合花鲈早期幼鱼的生长。研究结果将为北方海域花鲈繁育适宜盐度和pH处理的设定,及提高花鲈孵化率、育苗成活率与早期苗种推广提供基础资料。     

Pacific sardine (Sardinops sagax, Jenyns 1842) landings prediction. A neural network ecosystemic approach

In this study the performances of computational neural networks (CNNs), multiple linear regressions (MLRs) and generalised additive models (GAMs) to predict Pacific sardine (Sardinops sagax) landings and to analyse their relationships with environmental factors in the north area off Chile were studied. For this purpose several local and global environmental variables and indexes (sea surface temperature, sea level and Ekman transport index in the Chilean coast and, sea surface temperature in the area Niño 3 + 4 and Niño 1 + 2, and the south oscillation index) were considered as inputs or independent variables. Additionally, several CNNs were calibrated and validated adding the anchovy (Engraulis ringens) landings in the same area as model inputs. The time lags of the variables considered were selected through analysis of the non-linear cross-correlation functions and an alternative form of sensitivity analysis based on the approach of the missing value problem. The analysis of error measures with validation data set showed that the best results were obtained when local and global variables were used separately and combined with anchovy landings. Globally, the best result was given by a CNN with 18 input variables (model CNN 6(II) which only considered global variables and anchovy landings) and 10 neurons in a hidden layer. For this configuration the explained variance was slightly higher to 86% which supposed a standard error of prediction of 7.66%. These results were significantly better than those obtained with MLRs and GAMs. The strong correlation between predicted and observed sardine landings suggests that CNNs captured the trend of the historical data. Also, the generalisation capacity together the sensitivity analysis allowed us to identify the variables with a high weight in the model and partially to interpret the statistical functional relationships between these environmental variables and sardine landings.     

花(鱼骨)对饲料中磷的营养需求

以酪蛋白-明胶为蛋白源,磷酸二氢钾为磷源配制6个磷水平(0.32%、0.58%、0.83%、1.09%、1.35%和1.59%)的等氮等能的精制饲料,饱食投喂花(鱼骨)[初始体质量为(7.97±0.07)g]8周,探讨饲料磷水平对花(鱼骨)生长、饲料利用、骨组织无机物含量、血清磷的影响,确定花(鱼骨)对饲料磷的需要量.试验结果表明:(1)当饲料磷水平从0.32%上升到0.83%时,增重、饲料效率随之而提高,但超过此水平后各组差异不显著(P0.05),折线模型分析饲料磷水平与相对增重率之间的关系,花(鱼骨)获得最大增重时饲料磷的最低需求为0.91%.(2)脊椎骨、鳃盖骨和鳞片的矿物组成受到饲料磷水平的显著影响(P<0.05),二次曲线回归方程拟合饲料磷水平与脊椎骨灰分率的关系,花(鱼骨)脊椎骨达到最大矿化时饲料磷为1.17%.(3)血清磷水平随饲料磷的增加而升高,饲料磷对血清钙没有显著影响.综合分析体增重、磷存留率、骨灰分含量、血清磷浓度等多项生物学指标,花(鱼骨)对饲料磷的需要量为0.91%～1.17%.     

花鲈鳃与鳔器官发育的组织学与形态学观察

为阐明花鲈鳃与鳔器官的发生机制,实验采用连续组织切片技术接合形态学观察对出膜后1～45 d花鲈胚后发育的鳃与鳔器官的发生、发育过程进行了系统的观察与研究。结果显示,花鲈仔稚鱼鳃的胚后发育分为4个阶段,鳃原基出现期(0～3 d)、鳃丝分化期(4～14 d)、鳃小片分化期(15～25 d)与鳃器官完善期(26～45 d)。在水温15～18°C条件下,花鲈孵化后的第1天,鳃原基出现;孵化后的第15天,仔鱼假鳃上分化出鳃小片结构;孵化后的第25天,仔鱼各鳃弓上均分化出鳃小片结构;孵化后的第45天,稚鱼鳃结构发育完全,与成鱼相同。组织学观察结果显示,花鲈鳔器官的发育时期分为形成、扩张、充气和退化4个阶段。花鲈初孵仔鱼未出现鳔原基,在孵化1 d后,仔鱼出现鳔原基,5 d后仔鱼鳔开始扩张,11 d后仔鱼鳔充气完成,13 d后仔鱼鳔开始退化。     

鲤和草鱼IL17受体基因家族的全基因组识别、起源进化及表达分析

为了研究鲤科鱼类最具代表性的二个物种—鲤和草鱼IL17受体基因家族的起源进化,实验采用比较基因组学和生物信息学的方法,分别在鲤和草鱼基因组数据库进行序列比对和注释,然后对得到的基因进行结构域和系统发育学分析,最后在12个不同组织中进行基因表达分析研究。结果显示,在鲤和草鱼中分别注释得到9个和5个IL17受体基因家族成员。系统发育分析显示,该基因家族不存在鱼类特有的基因,在硬骨鱼类中具有一定的保守性。比较基因组学结果显示,与四足动物相比,大多数硬骨鱼类中IL17受体基因没有明显增多。鲤与草鱼等其他硬骨鱼类相比,除IL17RB以外,其余IL17受体基因家族成员均加倍。不同组织的表达分析结果显示全基因组复制后不同基因拷贝的功能发生了分化。研究表明,虽然硬骨鱼经历第三轮全基因组复制,但是由于复制发生时间久远,大多数基因已经发生改变或退化,进而在基因组中丢失。而鲤第四轮基因组复制时间发生在820万年前,复制发生时间较近,故复制后的基因基本得以保留。但是对于一些具有特殊功能的高度保守基因(例如IL17RB),也会发生在极短时间内出现丢失现象。鲤和草鱼健康组织的表达谱分析结果同样表明,鲤IL17受体基因的不同拷贝之间已经发生了快速进化及亚功能化,并且这种现象在鲤四倍体基因组中普遍存在。     

花鲈等渗点分析及海水淡化对Na+/K+/Cl-浓度、Na+-K+-ATP酶活性及基因表达的影响

广盐性鱼类有着较为复杂的渗透调节机制,能够在较大盐度范围内存活并生长。通常认为鱼类在等渗环境下用于渗透调节的代谢能量最少,有利于鱼类生长。本实验首先根据不同盐度下花鲈血清渗透压对应水体渗透压的变化,计算得到花鲈的等渗点为11.4。而后进行海水淡化和淡水适应两个阶段的盐度实验,通过对花鲈两个阶段中血清渗透压、Na~+/K~+/Cl-浓度、Na~+-K~+-ATP酶(Na~+-K~+-ATPase,NKA)活性及其基因表达的测定,探讨了海水淡化对花鲈的生理影响与分子响应机制。在盐度实验中,Na~+和Cl-浓度变化和血清渗透压变化趋势一致,在淡化阶段显著下降,在淡水适应阶段逐渐恢复稳定,但仍低于起始水平。鳃组织中NKA基因表达结果显示,NKAα1a和NKAα1b的变化趋势与Na~+-K~+-ATP酶活性变化趋势基本一致,在淡化阶段显著下降,随后回升至稳定,不同的是,淡水适应后花鲈NKAα1a表达量与盐度30组无显著性差异,而NKAα1b表达量显著低于盐度30;NKAα3在淡化第1天,表达量显著降低,且在淡水(盐度0)环境下一直处于较低水平;NKAβ在淡水适应过程中的表达量总体高于淡化过程。相关性分析中,海水淡化阶段,Na~+-K~+-ATP酶和NKAα1a呈极显著相关。本研究通过对花鲈等渗点以及海水淡化和淡水适应阶段相关离子、酶、基因表达的测定,弥补有关花鲈等渗点研究的空白,同时为花鲈的淡化养殖提供一定的理论指导。     

Effect of EPA/DHA ratios on the growth and survival of Galaxias maculatus (Jenyns, 1842) larvae reared under different salinity regimes

Despite the importance of certain highly unsaturated fatty acids in osmotic regulation, few studies have been addressed to determine the essential fatty acid requirements for a given species cultured under different salinities. As Galaxias maculatus is a diadromic species, the present study aimed to determine the effect of salinity on the optimum dietary EPA/docosahexaenoic (DHA) ratio for survival and growth during the larval stages. Larvae were fed for 20 days with rotifers containing two different EPA/DHA ratios (low: 0.64 and high: 2.18) at three different salinities (0, 10 and 15 g L^?1). The results of this study showed a marked effect of water salinity on larval dietary lipid utilization in G. maculatus larvae. These results suggested that G. maculatus larvae reared at higher salinities may have a higher dietary requirement for DHA, whereas larvae reared at 0‰ showed higher requirements for EPA. The overall results of the present study indicate that even small changes in salinity can determine the optimum dietary EPA/DHA ratio and the quantitative essential fatty requirements of fish. This may have important repercussions and affect the rearing performance of G. maculatus cultured under different salinities.     

魁蚶各组织溶菌酶活性对鳗弧菌侵染的响应

为了有效防治细菌及其他病原微生物对魁蚶等贝类的危害,本实验研究了魁蚶各组织中溶菌酶活性对鳗弧菌侵染的响应过程,以期探讨魁蚶体内溶菌酶的免疫功能。本实验采用注射活菌的方法侵染20月龄魁蚶个体,随机选取16只个体,在每只个体的斧足处注射1 mL(约1×10~9个)鳗弧菌菌悬液作为感染组;随机选取16只个体不注射鳗弧菌作为对照组。两组魁蚶分别于洁净海水中暂养4、12、24和48 h后,每组随机取4只魁蚶个体的血液、外套膜、鳃、斧足、肝胰腺和闭壳肌等组织,采用ELISA试剂盒测定其溶菌酶含量变化。结果显示,对于鳗弧菌的侵入,魁蚶血液中溶菌酶含量由正常低值迅速增高并一直维持较高的含量,说明血液是魁蚶机体防御病原菌的主要免疫组织之一;魁蚶外套膜在无感染的情况下,对外界水环境的干扰始终保持较高的溶菌酶含量;鳃、斧足的溶菌酶含量均在注射细菌24 h之后明显高于正常值,说明外套膜、鳃、斧足作为魁蚶机体与外界接触的第一道屏障也能应对病原菌入侵,但反应较血液延迟;肝胰腺和闭壳肌的溶菌酶含量变化不明显,推测肝胰腺和闭壳肌不是魁蚶的重要免疫组织或器官。本实验结果可为魁蚶抗病选育及免疫机理方面的研究提供相关的参数。     

豆粕替代鱼粉对牛蛙生长、体组成、消化酶活力及肝脏生化指标的影响

为减少牛蛙饲料鱼粉使用量以降低养殖成本,研究了豆粕替代饲料中不同比例的鱼粉对牛蛙的生长性能、体组成、肠道消化酶活力和肝脏生化指标的影响。用豆粕分别替代0%、20%、40%、60%、80%和100%的鱼粉配制出6种等氮等能的实验饲料,每组饲料设3重复,养殖牛蛙60 d。结果显示,豆粕替代鱼粉对牛蛙摄食率、成活率、肝体指数、脏体指数、蛙体水分和灰分含量、蛙腿肌肉组成以及肝脏丙二醛含量的影响不显著;豆粕100%替代鱼粉显著降低牛蛙增重率、特定生长率、饲料系数、蛋白质效率、蛋白质累积率;随豆粕替代鱼粉比例的提高,牛蛙的肥满度和后腿指数呈下降趋势,替代100%鱼粉显著降低牛蛙肥满度,替代60%鱼粉显著降低牛蛙后腿指数;替代80%鱼粉显著降低牛蛙全体粗蛋白的含量;牛蛙全体粗脂肪含量随替代鱼粉比例的提高呈上升的趋势,替代100%鱼粉组粗脂肪含量最高;随着替代比例的提高,牛蛙肠道蛋白酶的活力显著降低,而肠道淀粉酶和脂肪酶活力显著提高。豆粕替代鱼粉显著影响肝脏超氧化物歧化酶和过氧化氢酶活力,其中超氧化物歧化酶活力最低值出现在替代80%鱼粉组,过氧化氢酶活力最低值出现在替代100%鱼粉组。基于以上实验结果,建议牛蛙饲料中豆粕可替代鱼粉的比例为60%~80%。     

杜仲对草鱼生长、肌肉品质和胶原蛋白基因表达的影响

为研究杜仲对草鱼生长性能、肌肉品质及胶原蛋白基因COL1A1和COL1A2表达的影响,实验采用初始体质量为(215.0±0.4)g的草鱼120尾,随机分为2处理组(每组3重复,每重复20尾鱼),分别饲喂基础饲料(对照组)和添加2%杜仲的实验饲料(杜仲组),养殖时间为8周。结果显示,与对照组相比,添加2%杜仲对草鱼生长性能无显著影响,但能显著增加肌肉、皮肤和肝脏胶原蛋白水平,增加肌肉总必需氨基酸(TEAA)、总氨基酸(TAA)水平。2%杜仲可显著降低草鱼肌肉的冷冻失水率、离心失水率,但对肌纤维密度和肌纤维直径无显著影响。在胶原蛋白基因表达方面,2%杜仲显著增加了第4周、8周时草鱼的肌肉、皮肤和第8周时的肝脏组织COL1A1、COL1A2基因m RNA表达量。研究表明,饲料中添加2%杜仲可改善大规格草鱼的肌肉品质。     

Molecular evidence for the lack of transmission of the monogenean Sparicotyle chrysophrii (Monogenea, Polyopisthocotylea) and isopod Ceratothoa oestroides (Crustacea, Cymothoidae) between wild bogue (Boops boops) and cage-reared sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax)

In the Mediterranean area, wild fish have often been suggested as either the reservoirs of the causative agents or at least the carriers of the pathogens responsible for disease outbreaks in cultured fish. However, no epidemiological investigations on actual pathogen/disease interactions between farmed and wild fish have been conducted even for the most important fish pathogens. Only sporadic isolations and identifications of various pathogens in wild fish have been done and real associations with the pathological conditions that exist within the farm environment and vice versa have not been established. Monogenean ectoparasite Sparicotyle chrysophrii and isopod Ceratothoa oestroides are commonly found in the Mediterranean cage-reared sea bream and sea bass and in the surrounding wild fish population. Both species were recognized as pathogens that seasonally inflict serious losses in fingerlings and juveniles of sea bream and sea bass, being potentially propagated and exchanged during wild and caged fish interaction. In order to evaluate the degree of pathogens transfer between wild and farmed fish, we investigated genetic population structures of these two important parasitic pathogens inferred by mtDNA cytochrome oxidase I locus. Parasites isolated from wild and farmed fish on the two most productive Adriatic fish farms showed genetic heterogeneity, contradicting widely accepted hypothesis of cross-contamination, at least in case of S. chrysophrii and C. oestroides. As far as we know, this is the first report that in a study of pathogen transfer molecular evidence was employed to asses the genetic population structure of shared parasites.     

鲢鳙混养对三角帆蚌生长和养殖水质影响的围隔实验

2008年4月23日—9月21日通过围隔实验,研究了不同鲢鳙混养比例对三角帆蚌生长及水化学指标的影响。实验中鲢鳙混养比例设置了6个水平,分别为0/0(对照组),100/0,70/30,50/50,30/70和0/100。实验开始和结束时测量三角帆蚌湿重,壳长和壳宽。每个月上下旬测量围隔水化学指标包括NO3N、NO2N、NH3N、TN、TP、PO4P和COD。实验结果表明,鲢鳙混养比例100/0的围隔蚌壳长相对生长率显著低于混养比例0/0,50/50和0/100的围隔(P<0.05),而不同混养比例下蚌的成活率、蚌壳宽及蚌重增长均无显著差异(P>0.05)。从水质来看,混养比例30/70围隔TP显著低于100/0(P<0.05),COD显著低于100/0及70/30(P<0.05),NH3N显著低于100/0(P<0.05)以及PO4P显著低于70/30(P<0.05)。因此,综合蚌生长及水质指标,混养比例30/70围隔对三角帆蚌养殖最有利。     

盐度胁迫对尼罗罗非鱼免疫相关指标的影响

为探究盐度胁迫对尼罗罗非鱼免疫的影响,对体质量(35.0±5.0) g的尼罗罗非鱼进行了急性和慢性的盐度胁迫实验,对免疫相关指标进行了检测和分析。在急性盐度胁迫中,设置0、5和15盐度组,分别在胁迫后6、12、24、48和96 h进行取样,检测血清SOD、CAT、GSH-Px和AKP的活性。在慢性实验中,设置0、10、20和30盐度组,胁迫8周后检测血清SOD、CAT、GSH-Px和AKP活性,并进行了无乳链球菌易感性实验。结果显示:①血清中SOD活性在急性盐度胁迫6、12和24 h时都有随盐度上升而上升的趋势,但在96 h时盐度15组酶活性显著低于盐度5组;在慢性盐度胁迫下,各组的酶活性呈现出随着盐度升高而显著性下降的趋势。②血清CAT活性在急性盐度胁迫下12和24 h时呈现出随着盐度升高而显著下降的趋势;在慢性胁迫下不存在显著性差异。③血清中GSH-Px活性在急性和慢性胁迫后,均呈现随着盐度升高而降低的趋势。④血清AKP活性在胁迫后6 h随盐度升高呈现出显著下降趋势;在慢性盐度胁迫下,盐度20组显著低于其他实验组。⑤尼罗罗非鱼对无乳链球菌易感性实验中,盐度10组的易感性和盐度0组之...     

Brachionus vs Artemia duel: Optimizing first feeding of Upogebia pusilla (Decapoda: Thalassinidea) larvae

Larval rearing of many marine organisms is dependent on the availability of live food. The aim of this study was to optimize larval first feeding for the mud shrimp Upogebia pusilla, by comparing the effectiveness of the two most commonly used live feeds: Brachionus plicatilis and Artemia sp. nauplii. Survival, larval duration, molt synchronism and megalop size were compared using five feeding treatments: Artemia from zoea I to IV (B0), Brachionus during zoea I and Artemia from zoea II to IV (B1), Brachionus during zoea I and II and Artemia during zoea III and IV (B2), Brachionus from zoea I to III and Artemia during zoea IV (B3) and Brachionus from zoea I to IV (B4). The proportion of larvae that reached the megalop stage was 0.00% in treatment B0, 3.33% in treatment B1, 33.33% in treatment B2, 66.67% in treatment B3 and 76.67% in treatment B4. Larvae fed on rotifers until zoea III or zoea IV stages had a higher survival but no differences were found either in time to reach megalop or in megalop size. This study demonstrates that rotifers are essential for the survival and development of U. pusilla early larval stages but that rotifers can be successfully replaced by Artemia nauplii in the zoea IV stage.     

饲用枯草芽孢杆菌HGcc-1对鲤肠肝健康、血清补体及肠道菌群的影响

为了研究枯草芽孢杆菌HGcc-1对鲤肠肝健康、血清补体和肠道菌群的影响,实验选择体质量为(13.10±0.39) g健康鲤,随机分为HGcc-1添加组和对照组,养殖20周后测定生长指标,用试剂盒检测了鲤血清内毒素(LPS)、谷丙转氨酶(ALT)、谷草转氨酶(AST)、总补体和溶菌酶,并对肠道菌群进行了16S rRNA测序,同时将添加组和对照组的肠道菌群转接至无菌斑马鱼,然后检测无菌斑马鱼体内毒素结合蛋白(LBP)、ALT、AST的水平和C3、C4基因表达量;最后还检测了HGcc-1直接作用于无菌斑马鱼时,无菌斑马鱼的ALT、AST的水平和C3、C4基因表达量。结果显示,HGcc-1对鲤的增重率无显著影响;与对照组相比,饲料中添加HGcc-1显著降低鲤血清内毒素、ALT和AST水平;同时HGcc-1添加组血清总补体水平显著升高。在门水平上,HGcc-1添加组中梭杆菌门丰度比对照组增加了47.1%;变形菌门丰度比对照组减少了70.7%;在属水平上,HGcc-1添加组中鲸杆菌属(的丰度比对照组增加了47.1%;柠檬酸杆菌属和气单胞菌属(的丰度比对照组分别减少了56.6%和70.9%。利用无菌斑马鱼模型进一步发现,HGcc-1添加组鲤肠道菌群显著降低了无菌斑马鱼LBP含量和AST水平,显著上调了无菌斑马鱼补体C3和C4基因表达;与此同时,HGcc-1与无菌斑马鱼直接互作也降低了鱼体ALT和AST水平。研究表明,饲料中添加枯草芽孢杆菌HGcc-1能够改善鲤肠肝健康、血清补体以及肠道菌群稳态。本研究为枯草芽孢杆菌HGcc-1的下一步应用奠定了理论基础。     

植物乳杆菌(LP HMX-3)对仿刺参生长、消化、免疫和肠道菌群的影响

为探究植物乳杆菌LP HMX-3对仿刺参生长性能、消化酶活性、免疫能力和肠道菌群的影响,选择初始体重为(4.22±0.05)g的仿刺参,随机分为对照组(C组)和LP HMX-3添加组即10⁵ CFU/g的LL组和10⁷ CFU/g的LM组,进行为期8周的养殖实验。结果显示,(1)LP HMX-3显著提高了仿刺参的终体重、增重率以及特定生长率,且LL组的生长指标更优;(2)LL组的肠道淀粉酶和LM组的肠道脂肪酶活性显著高于C组,说明LP HMX-3可能提高仿刺参的消化利用率;(3)LL组和LM组体腔液的碱性磷酸酶和过氧化氢酶活性以及LM组的酸性磷酸酶活性均显著高于C组,此外,LL组和LM组体腔细胞Aj-p105和Aj-catalase表达量以及LM组的Aj-C3表达量显著高于C组,说明LP HMX-3可增强仿刺参的免疫力;(4)由16S r DNA V4区测序可知,α多样性指数显示,LP HMX-3显著提高了仿刺参肠道微生物丰富度和均匀度,但LL组和LM组差异不大;β多样性分析显示,LL组和LM组的微生物种群结构相似,但明显不同于C组;(5)在...     

Genetic variations in survival of rohu carp (Labeo rohita, Hamilton) after Aeromonas hydrophila infection in challenge tests

A challenge test against Aeromonas hydrophila was conducted using 2062 rohu carp (Labeo rohita) fingerlings obtained from 52 dams and 87 sires (87 full-sib families) of two year-classes (2003 and 2004). Attempts to establish a cohabitant challenge model were not successful. Therefore, fish were challenged by intraperitoneal injection with A. hydrophila in two replicate tanks per year-class, and dead fish were collected hourly. The mortality reached its peak at 16–22 h after challenge and had almost completely stopped after 58 h. The test was terminated after 382 h at which the average survival was 43.9 and 48.9% in the two 2003 year-class tanks, and 77.1 and 35.8% in the two 2004 year-class tanks. Heritability estimates for survival were obtained from sire and dam threshold models (THR) and sire and dam linear repeatability models (LINR). For both types of models the heritability estimates based on data from single tanks were not consistent. For both year-classes, data from one of the two challenged tanks demonstrated significant additive genetic variation in survival during the A. hydrophila infection, whereas the heritability estimates were not significantly different from zero for the other tank. Further, genetic correlation between survivals in the two replicate tanks in each year-class was not significantly different from zero. The differential results from the replicate tanks demonstrate that additional challenge test experiments are needed before firm conclusions can be drawn about the magnitude of additive genetic variation for survival to aeromonasis in rohu carp. A cohabitant challenge model that allows the testing of important defence mechanisms in the skin and mucous membranes of the fish might have been more appropriate. To establish a valid cohabitant challenge model for rohu carp should be given high priority.