大渡河软刺裸裂尻鱼（Schizopygopsis malacanthus）游泳能力研究

为了探究大渡河软刺裸裂尻鱼的游泳能力,为大渡河水域过鱼设施的设计提供基础数据支持以及充实鱼类游泳能力机制的数据资料。本研究采用递增流速法,用自制Brett-type水槽对大渡河软刺裸裂尻鱼的感应流速、临界游泳速度、突进游泳速度进行测试。结果表明,在水温范围为11.9~14.1℃条件下,体长为15~21.5cm,体重为34.8~152.9g的大渡河软刺裸裂尻鱼的绝对感应流速为0.084~0.0948m/s,相对感应流速为0.321~0.588BL/s,相对感应游泳速度随体长增大而减小;绝对临界游泳速度（Ucrit）为0.61~1.31m/s,相对临界游泳速度为4.16~5.076BL/s,这两者均随体长增大而增大;大渡河软刺裸裂尻鱼的绝对突进游泳速度（Uburst）为1.02~1.4m/s,与体长关系并不显著（P>0.05）,相对突进游泳速度为5.73~8.36BL/s,随体长增加而减小。通过视频回放发现,试验鱼突进游泳速度测试过程分为三个阶段：占突进速度0~29%,速度范围为0~0.4m/s;占突进速度29%~60%,速度范围为0.4~0.84m/s;占突进速度60%~100%,速度范围为0.84~1.4m/s。各阶段的静止不动、平稳摆动、冲刺-滑行三种游泳状态所占比例有显著不同。本研究可为以大渡河软刺裸裂尻鱼为过鱼对象的过鱼设施设计提供流速指标参考。     

应用于鱼道设计的新疆木扎提河斑重唇鱼的游泳能力测试

为了探究斑重唇鱼的游泳能力,给过鱼设施设计和鱼类游泳行为学研究提供基础参数,本研究以木扎提河野生斑重唇鱼(全长TL=12～16 cm)为研究对象,测定了其在(16.6±1.6)℃水温下的感应流速、临界游泳速度、爆发游泳速度及持续与耐久游泳能力。结果显示,斑重唇鱼感应流速为(0.18±0.02)m/s,相对感应流速为(1.40±0.23) BL/s (BL为体长);临界游泳速度为(1.02±0.15) m/s,相对临界游泳速度为(8.58±1.65) BL/s;爆发游泳速度为(1.39±0.17) m/s,相对爆发游泳速度为(10.92±1.86) BL/s;最大持续游泳速度为0.87 m/s,最大耐久游泳速度为1.37 m/s,与平均爆发游泳速度相近。其持续游泳时间与流速呈负相关(l g T=?5:136X+8:504)。当以斑重唇鱼为主要过鱼对象时,建议为吸引鱼类进入鱼道,进口流速设计为1.02～1.39 m/s,休息池主流设计为0.20～1.02 m/s,鱼道竖缝处流速宜低于0.85 m/s。鱼道长度为1 000 m时,鱼道内平均水流速度应低于0.78m/s。本研究结果可为新疆木扎提河流域鱼类游泳能力研究提供参考,对保护日益减少的鱼类资源具有重要意义。     

温度梯度对四大家鱼临界游泳速度的影响

在水利工程建设中,鱼道是一项重要的生态补偿措施,研究鱼类游泳能力可为鱼道等过鱼设施设计提供参考数据。本研究以四大家鱼为研究对象,分别测定其在不同温度(10℃、15℃、20℃、25℃和30℃)梯度下的临界游泳速度。结果显示,在10℃~30℃温度范围内,青鱼(Mylopharyngodon piceus)、草鱼(Ctenopharyngodon idellus)、鲢(Hypophthalmichthys molitrix)、鳙(Aristichthys nobilis)的相对临界游泳速度分别为(3.93±0.24~9.94±1.65) BL/s、(3.50±0.48~10.55± 2.07) BL/s、(0.95±0.04~4.68±0.58) BL/s、(2.22±0.18~3.95±0.23) BL/s [BL为实验鱼的体长(cm)]。在水温为10℃~20℃范围内,四大家鱼的绝对临界游泳速度和相对临界游泳速度均随水温升高而增大,基本表现为在20℃时达到最大值,随后趋于稳定,且20℃组四大家鱼游泳能力显著高于15℃组和10℃组,20℃组、25℃组和30℃组四大家鱼临界游泳速度均无显著性差异。此外,随着温度的升高,草鱼的游泳能力增加速度高于其他3种鱼。相同温度条件下,草鱼和青鱼的临界游泳速度相近,均极显著高于鲢和鳙(P<0.01)。当考虑过鱼对象为四大家鱼时,建议延长鱼道在夏季的开放时间,将鳙的临界游泳速度作为鱼道设计的主要依据。     

鳙幼鱼4种典型游泳状态特性研究

在23±0.5℃水温条件下,利用游泳行为测试水槽分析早期发育阶段鳙幼鱼（Hypophthalmichthys nobilis）（5.0～9.0cm,2.5～11.5g）游泳行为特性与水流流速变化的响应关系。结果表明该体长范围鳙幼鱼的平均临界游泳速度为0.468±0.161m/s;平均突进游泳速度为0.672±0.154m/s,且绝对临界游泳速度和绝对突进游泳速度均随体长的增加而线性增加,相对突进游泳速度随体长的增加而线性减小;绝对突进游泳速度与绝对临界游泳速度存在如下关系： ;在测试突进游泳速度中鱼类游泳行为随水流流速变化存在4种游泳状态相互穿插（顶流前进、顶流后退、顶流静止、顺流而下）,根据鱼类运动过程中的四个阶段分别对应的4种游泳状态,得到以鳙幼鱼为过鱼对象的鱼道池室主流流速为16.0～46.5cm/s;对于鱼道高流速区的竖缝、孔口等最佳流速应为46.5～85.4cm/s。本研究成果补充了四大家鱼游泳特性指标,为四大家鱼资源保护、鱼类洄游通道建设提供参考依据。     

异齿裂腹鱼游泳能力初探

为了摸清雅鲁藏布江特有种异齿裂腹鱼(Schizothorax oconnori)的游泳能力,以野生鱼种为实验对象,通过丹麦Loligo System公司的环形试验水槽测试了异齿裂腹鱼的临界游泳速度、突进游泳速度和持续游泳速度。结果显示,异齿裂腹鱼的临界游泳速度随体长的增大而增加,相对临界游泳速度随体长的增大而减小,其临界游泳速度与体长的关系为Y1=-39.369+13.23X-0.371X2+0.004X3(Y1是绝对临界游泳速度,X为体长)。突进游泳速度随体长的增加而近似呈线性递增趋势,而相对突进游泳速度随体长的增大而减小。在三个固定流速(60cm/s、80 cm/s、100 cm/s)下,初步确定60 cm/s为异齿裂腹鱼的持续游泳速度,80 cm/s、100 cm/s为耐久游泳速度。研究成果以期为青藏高原地区鱼类行为学的研究提供基础资料,为鱼道等过鱼设施的设计提供参考资料。     

障碍物对鲢幼鱼游泳动力学的影响

为了解鱼在复杂水流环境中的运动行为,提升鱼道过鱼效果,实验通过在水槽中放置障碍物,分析不同来流速度(1,3和5 BL/s)(BL/s即体长每秒)下鲢幼鱼顶流静止和顶流前进时的游泳动力学表现,提取的游泳动力学指标有摆尾频率、摆尾幅度、对地游泳速度、游泳加速度和运动步长。结果发现,半流速度1 BL/s下,与自由来流相比,鲢幼鱼在障碍物后方顶流静止时,摆尾频率降低,摆尾幅度增加;顶流前进时,摆尾频率、对地游泳速度、游泳加速度和运动步长降低,摆尾幅度增加。半流速度3 BL/s下,障碍物有助于节省鱼类运动能量的消耗。在有障碍物的水流中,顶流静止时的摆尾频率随流速的增加而增加;顶流前进时,摆尾频率、摆尾幅度和游泳加速度随流速增大而增大,而运动步长随流速增大而减小。位置偏好研究表明,当流速为3 BL/s时,鲢幼鱼明显集中在距离障碍物后方约5～30 cm处游动,停留时间占比达92.5%,可能采用了卡门步态的运动模式;当流速为1和5 BL/s时,鲢幼鱼没有表现出非常明显的位置偏好;在自由来流中,鲢常贴壁游泳,亦没有明显的位置偏好,表明障碍物和流速的结合可为鱼类提供水流藏匿场,研究结果为鱼道设计提供重要参考依据。     

应用于鱼道设计的新疆木扎提河斑重唇鱼的游泳能力测试

为了探究斑重唇鱼的游泳能力，给过鱼设施设计和鱼类游泳行为学研究提供基础参数，本研究以木扎提河野生斑重唇鱼(全长TL=12~16 cm)为研究对象，测定了其在(16.6±1.6) ℃水温下的感应流速、临界游泳速度、爆发游泳速度及持续与耐久游泳能力。结果显示，斑重唇鱼感应流速为(0.18±0.02)m/s，相对感应流速为(1.40±0.23) BL/s (BL为体长)；临界游泳速度为(1.02±0.15) m/s，相对临界游泳速度为(8.58±1.65) BL/s；爆发游泳速度为(1.39±0.17) m/s，相对爆发游泳速度为(10.92±1.86) BL/s；最大持续游泳速度为0.87 m/s，最大耐久游泳速度为1.37 m/s，与平均爆发游泳速度相近。其持续游泳时间与流速呈负相关(${\rm lg}T = - 5.136{{X}} + 8.504$)。当以斑重唇鱼为主要过鱼对象时，建议为吸引鱼类进入鱼道，进口流速设计为1.02~1.39 m/s，休息池主流设计为0.20~1.02 m/s，鱼道竖缝处流速宜低于0.85 m/s。鱼道长度为1 000 m时，鱼道内平均水流速度应低于0.78 m/s。本研究结果可为新疆木扎提河流域鱼类游泳能力研究提供参考，对保护日益减少的鱼类资源具有重要意义。     

鲢幼鱼游泳能力及游泳行为的试验研究

为了探究四大家鱼的游泳能力,指导鱼道水力学设计,提高鱼道过鱼成功率,增殖鱼类资源总量,以四大家鱼之一的鲢(Hypophthalmichthys molitrix)为试验对象,研究其游泳能力及游泳行为。在(30±1)℃水温下,采用流速递增法,鲢的体长7.3~16.8 cm,体重6.10~66.50 g,按体长将鲢分为(8.17±0.59)cm、(10.09±0.53)cm、(11.84±0.67)cm、(13.94±0.68)cm、(15.90±0.64)cm共计5个试验组。结果表明,鲢的临界游泳速度为52~100 cm/s,相对临界游泳速度为5.90~7.14 BL/s,摆尾频率为98.7~432.2次/min。鲢的临界游泳速度随体长增加而增大,其线性拟合方程为Ucrit=4.908L+17.63(R2=0.998);其相对临界游泳速度随体长增加而减小,线性拟合方程为U'crit=-0.130L+8.025(R2=0.979);在整个试验过程中,根据鱼类对水流速度的游泳行为响应,鲢摆尾频率随水流速度的增大而增加,两者呈线性关系;在相同流速下,较长个体鲢的摆尾频率显著小于较小的个体。     

鲢幼鱼非疲劳贴网及姿态转换行为研究

流速是影响鱼类生存与繁衍栖息的重要因子。为了了解鱼类在中等流速区的游泳行为,探究其对水流的适应特征,利用鱼类游泳能力测定装置,以鲢(Hypophthalmichthys molitrix)幼鱼[体重(9.82±3.81) g,体长(8.56±1.11) cm)]为对象,采用递增流速法,分析了游泳过程中的非疲劳贴网行为与姿态转换行为。结果表明,在22℃水温条件下,鲢幼鱼平均相对临界游泳速度(critical swimming speed,U_(crit))相比其体长(body length,BL)为(6.00±0.93)BL/s;其非疲劳贴网速度(no-fatigue impingement speed,U_(imp))与临界游泳速度呈线性正相关,U_(crit)=1.03 U_(imp)+1.26 (R~2=0.86,P0.01);姿态转换速度(gait transition speed,U_(tran))与临界游泳速度呈线性正相关,U_(tran)=0.59 U_(crit)+1.55 (R~2=0.43,P0.01);非疲劳贴网速度与姿态转换速度呈线性正相关,U_(tran)=0.51U_(imp)+2.72 (R~2=0.41,P0.001)。在中等流速范围内(2～4 BL/s),实验鱼摆尾频率(tail beat frequency, TBF)和单次摆尾周期前进距离(stride length, SL)均随流速增加而增大。首次出现非疲劳贴网的流速为4.62 BL/s,流速增至5.08 BL/s时出现姿态转换行为。发生姿态转换后,TBF开始下降,而SL随流速增加快速增大。研究显示,鲢幼鱼非疲劳贴网行为对游泳能力和姿态转换速度有显著影响,且非疲劳贴网行为与姿态转换行为之间也存在相互影响。研究结果可为自然环境中鱼类生态行为研究、鱼类资源保护及渔业管理提供参考。     

5种鱼类标志对草鱼临界游泳速度的影响

采用被动整合雷达标志法(PIT)、切鳍标记、荧光标记、超声波标志和T型标志这5种标志方法对草鱼(Ctenopharyngodon idellus)进行标记后,测定其临界游泳速度,研究5种不同标记对草鱼游泳能力的影响。将试验草鱼按不同体长分为3组:15~18 cm,18~21 cm,21~25 cm,每个体长组均设置对照组,并分别进行以上5种鱼类标志,测量标志后草鱼的绝对临界游泳速度和相对临界游泳速度。采用SPSS17.0统计软件进行数据的分析比较。研究结果表明,随着体长增加,草鱼的绝对临界游泳速度增大,相对临界游泳速度减小;超声波标志对3个体长组草鱼的临界游泳速度均有极显著影响(P0.01),标志后草鱼绝对临界游泳速度分别下降18.72%、16.40%、23.15%,相对临界游泳速度分别下降18.95%、17.78%、21.86%;T型标志对15~18 cm体长组草鱼的临界游泳速度有极显著性影响(P0.01),标志后草鱼绝对临界游泳速度下降8.35%,相对临界游泳速度下降9.30%,对体长大于18 cm的草鱼无显著性影响;PIT标志、切鳍标记和荧光标记对这3个体长组草鱼的临界游泳速度均无显著性影响(P0.05)。     

Susceptibility by amberjack (Seriola dumerili), yellowtail (S. quinqueradiata) and Japanese flounder (Paralichthys olivaceus) to Neobenedenia girellae (Monogenea) infection and their acquired protection

This study investigated: 1) susceptibility differences to infection by Neobenedenia girellae (Capsalidae) between amberjack Seriola dumerili (Carangidae), yellowtail S. quinqueradiata and Japanese flounder Paralichthys olivaceus (Paralichthyidae); 2) growth and egg production of N. girellae on each fish species; 3) acquired protection of each fish species against this parasite. The number of N. girellae on S. dumerili was significantly higher than on S. quinqueradiata and P. olivaceus when these fishes were exposed to oncomiracidia in the same aquarium. Neobenedenia girellae growth on S. dumerili was fastest and, thus the number of eggs laid by parasites on S. dumerili was greater than on the other two species. Seriola dumerili and P. olivaceus, which were previously infected with N. girellae and treated by freshwater bath, acquired partial protection against re-infection by N. girellae. The relative re-infection of three S. dumerili individuals out of eleven individuals was markedly low compared with the initial infection, and the relative initial infection and re-infection on two P. olivaceus out of eleven individuals was markedly low. The results of this study could be useful to control N. girellae infections when cultivating S. dumerili, S. quinqueradiata and P. olivaceus.     

AFLP-based genetic linkage map of marine shrimp Penaeus (Fenneropenaeus) chinensis

This paper presents the genetic linkage map of the Chinese shrimp Penaeus (Fenneropenaeus) chinensis constructed with 472 AFLP markers. A hundred F₁ progeny from an intercross between a female from the new variety “Yellow Sea No. 1” and wild caught male used for the mapping study. Two separate maps were constructed for each parent. The female linkage map consisted of 197 marker loci forming 35 linkage groups and spanned a total length of 2191.1 cM, with an average marker space of 13.5 cM. The male map consisted of 194 marker loci mapped to 36 linkage groups and spanned a total length of 1737.3 cM, with an average marker spacing of 11.0 cM. The level of segregation distortion observed in this study was 12.2%. The estimated genome length of P. chinensis was 3150.3 cM for the female and 2549.3 cM for the male, respectively. The observed genome coverage was 69.6% for the female and 68.1% for the male map. The linkage maps constructed in this study provide basic information for further linkage studies on Chinese shrimp, and more importantly, the construction of the maps are part of the work of the genetic breeding programs which will be used for growth discovered in the QTL analysis of P. chinensis.     

Composition in essential and non-essential elements of early stages of cephalopods and dietary effects on the elemental profiles of Octopus vulgaris paralarvae

During the present study, we aimed at providing a first look at the elemental composition of the early stages of cephalopods as an approach to their elemental requirements in culture. Essential and non-essential elemental profiles of the European cuttlefish Sepia officinalis, the European squid Loligo vulgaris and the common octopus Octopus vulgaris laboratory hatchlings and wild juveniles were analysed. In addition, for O. vulgaris we determined elemental profiles of mature ovary, eggs in different stages of development and followed possible effects of four dietary treatments during paralarval rearing, also analyzing elemental content of the live preys Artemia nauplii and Maja brachydactyla hatchling zoeae. Content was determined for essential (As, Ca, Cr, Co, Cu, Fe, K, Mg, Mn, Na, Ni, P, Rb, S, Sr, Zn) and non-essential (Ag, Al, Ba, Cd, Hg, Pb) elements. The content in non-essential elements found in hatchlings and juveniles of the three species analyzed here seems to be far lower in comparison with subadult and adult stages of coastal cephalopods. In the octopus eggs, the non-essential element concentrations remained globally low compared to hatchlings and juveniles indicating the absorption of these elements along the ontogenetic development. The elemental composition of the octopus ovary and of the eggs, hatchlings and juveniles of the three cephalopod species analyzed here showed a high content in S. As expected, the calcified internal shell of the cuttlefish, rich in Ca and Sr, originates the main difference between species. It is remarkable the richness in Cu of hatchling octopus, that may indicate a particular nutritional requirement for this element during the planktonic life. The reared octopus paralarvae feed on Artemia nauplii, a prey with relatively low Cu content, showed nearly half Cu content that the “natural” profile of octopus hatchlings or wild juveniles. This suggests a dietary effect and/or an indication of the poor physiological stage of the Artemia-fed paralarvae. At the present, the percentage of essential element absorption by food or seawater is unknown for cephalopods and should be determined in the future to understand their feeding requirements in culture.     

太平洋鳕RAG1和IgM基因荧光定量PCR方法的建立及初步应用

为研究太平洋鳕发育早期特异免疫系统形成的机制,通过RAG1和IgM基因的转录水平衡量特异免疫系统的发育特点.根据GenBank中RAG1和IgM的序列信息,分别设计1对特异引物,从太平洋鳕头肾中扩增得到RAG1和IgM的基因片段.将所获基因片段分别插入到克隆载体pMD18-T中,从而构建太平洋鳕RAG1和IgM基因的质粒标准品.建立并优化太平洋鳕RAG1和IgM基因绝对荧光定量PCR方法.为进一步验证该方法的可靠性,分别利用绝对定量和相对定量检验目的基因在太平洋鳕早期发育过程不同组织内的表达差异.以优化后的绝对荧光定量PCR方法检测不同发育时期太平洋鳕RAG1和IgM的表达情况.结果显示,RAG1的回归方程为y=-3.266x+33.77,回归系数R2=0.996;IgM的回归方程为y=-3.119x +27.61,回归系数R2 =0.998.绝对定量和相对定量结果在基因转录趋势上显现出一致性,即RAG1基因在胸腺和头肾中表达,且在胸腺中的表达量显著高于头肾中的表达量,在肝脏和脾脏中无表达;IgM基因在胸腺、头肾、肝脏和脾脏中均有表达,其中脾脏中表达量最高,其次是头肾.RAG1基因在太平洋鳕发育早期的表达水平很低,到61日龄(days posthatching,dph)至95 dph表达量显著提高;IgM基因在早期表达水平同样很低,到33 dph至61 dph才有明显表达,在95 dph时表达量显著提高.研究表明,本实验方法可靠,特异性较强,可成功对目标基因转录水平进行检测.     

Recruitment and effects of Discocotyle sagittata (Monogenea) infection on farmed trout

Farmed rainbow trout Oncorhynchus mykiss and brown trout Salmo trutta were monitored over 3 years for infection with the blood-feeding gill fluke Discocotyle sagittata. Parasite transmission is seasonal: new infections take place during summer/autumn, and transmission is generally negligible during winter/spring. There are 2 sources of infection for naïve fish-of-the-year: limited invasion when fish are in the raceways by riverborne larvae originating external to the farm; and internally, within the farm, when 0+ fish are transferred to ponds previously occupied by older cohorts of infected fish. Thereafter, infection levels continue to increase in rainbow trout primarily through transmission within the farm. Prevalence rose to 100% in 1+ fish by the end of their second summer. In O. mykiss, mean abundance reached 194 worms/host for 1+ fish (up to 489 worms/host) and 160 worms/host for 2+ fish. By contrast, in S. trutta, parasite prevalence never exceeded 85% and, after the first year's invasions, infection levels decreased over time: in 1+ and 2+ brown trout, parasite mean abundance was < 4 (maximum 15) worms/host. We present evidence of the detrimental effects of D. sagittata on the host: high burdens are associated with pale gills, decreased body condition and host mortality. Parasite burdens become overdispersed during the warmer part of the year, as prevalence and mean abundance increase. However, the degree of parasite overdispersion decreases over winter; we cannot distinguish whether decreased aggregation is due to parasite losses from infected fish (including immune-mediated parasite mortality) or parasite-induced host mortality.     

罗非鱼海豚链球菌病的病理学观察

采用光学显微镜和透射电子显微镜技术分别对患海豚链球菌病的罗非鱼的病理学变化进行了研究。分离的病原菌革兰氏染色呈阳性,透射电镜负染观察菌体球形或卵圆形,直径0.6~1.0μm,多数呈链状排列。组织学病变主要表现为全身多组织、器官水肿,出血、变性、坏死以及炎症反应,特别是肝、脾、肾和脑分别表现为肝炎,脾炎,间质性肾炎和脑膜炎。超微结构观察发现病鱼肝、脾、肾、脑、心肌和骨骼肌等器官的细胞超微结构都有较为严重的破坏,细胞核畸形,染色质浓缩或边集,粗面内质网囊泡化及脱粒,线粒体肿胀,嵴断裂或溶解消失。研究表明,海豚链球菌能造成罗非鱼全身性组织器官病变,致使器官功能障碍,正常生理代谢调节紊乱,最后导致死亡。     

吉富罗非鱼与奥利亚罗非鱼自繁与杂交 F1遗传特性与抗病力分析

以吉富罗非鱼与奥利亚罗非鱼为繁育亲本,采用完全双列杂交繁育4组F1,将初始规格基本一致的4组罗非鱼饲养100 d后,运用“加性-显性”遗传分析模型,分析了4组F1罗非鱼8个生长相关性状杂种优势、遗传效应以及与性状间的相关性.结果表明:(1)F1群体平均优势为0.129 4～0.368 4.除尾柄长超亲优势较大外,其他性状的群体超亲优势较小或表现出负向超亲优势.(2)8个性状的广义遗传率(HB)为0.714 2～0.995 3,表明加性效应和显性效应对性状的遗传变异影响极显著(P＜0.01).除尾柄长外,其他性状的狭义遗传率(HN)介于0.469 4～0.737 9,表明加性遗传方差在表型方差中所占比率较高.(3)体质量、全长、体长、体高、体宽、头长、尾柄长、尾柄高性状之间表型相关在0.776 6～0.999 7范围内,而遗传相关在0.994 1～1.000 0之间,表明这些性状间都存在极显著的正相关.取样结束后,采用3.95×106 CFU/mL的海豚链球菌菌液进行腹腔感染,吉富罗非鱼自繁组F1代12 h后出现死亡,而奥利亚罗非鱼自繁组F1192 h后才出现死亡.384 h后,吉富罗非鱼自繁组F1死亡率为40％,正反交组F1分别为20％和23.3％,奥利亚罗非鱼自繁组F1死亡率最低,为6.67％.研究结果表明,除尾柄长外,杂交F1的其他性状不具备超亲优势,然而杂交可以提高选育后代的抗病力.     

4种岩礁性鱼类视网膜感光细胞和最小分辨角的比较

运用组织学方法,对铠平鲉、花斑平鲉、大泷六线鱼和斑头六线鱼的性成熟个体视网膜光感受细胞和最小分辨角进行了比较研究。结果表明:(1)大泷六线鱼和斑头六线鱼视锥细胞的排列方式为4个双锥细胞围绕一个单锥细胞构成正方形或者菱形镶嵌结构,铠平鲉和花斑平鲉的双锥细胞排列成行,单锥细胞随机分布于4个双锥细胞之间;分析认为,大泷六线鱼和斑头六线鱼视锥排列方式更复杂,单锥细胞与双锥细胞的比值(SC/DC)更高,推测其具有更好的色觉。(2)铠平鲉和花斑平鲉视柱细胞与视锥细胞的比值(R/C)大于7∶1,而大泷六线鱼和斑头六线鱼的R/C小于3∶1;推测铠平鲉和花斑平鲉更适合在夜间活动,而大泷六线鱼和斑头六线鱼属白天活动的鱼类。(3)铠平鲉、花斑平鲉、大泷六线鱼和斑头六线鱼视锥细胞密度最高处分别位于视网膜的腹-颞(V-T)区、腹区(V)、腹-颞(V-T)区和背-颞区(D-T),与各自的生活习性和摄食行为相适应。(4)4种岩礁性鱼类的成熟个体中,铠平鲉的最小分辨角最大,其次为花斑平鲉和大泷六线鱼,斑头六线鱼的最小分辨角最小。分析认为,即使是同样栖息于礁区的鱼类,其视觉特征也存在差异,这或许可以为岩礁区选择性渔具的开发提供一些有益的参考。     

半滑舌鳎StAR基因克隆及其在不同组织的时空表达分析

利用半滑舌鳎性腺转录组测序获得的StAR基因部分序列,设计RACE引物,克隆了半滑舌鳎StAR基因的cDNA序列,全长为1 294 bp,5'端UTR为132 bp,3'端UTR为310 bp,开放阅读框(ORF)为852 bp,共编码283个氨基酸。将半滑舌鳎StAR基因与其他物种StAR基因进行氨基酸同源性分析,结果显示,半滑舌鳎StAR与塞内加尔鳎、大口黑鲈、花鲈、金头鲷的同源性都达到了85%,与虹鳟、斜带石斑鱼及日本鳗鲡的同源性分别为81%、83%和76%。雌、雄鱼不同组织StAR基因的表达分析表明,StAR基因在雄鱼性腺中高表达,在雄鱼的肝脏、脑及心脏中表达量较低,而在雄鱼的其他组织中不表达;在雌鱼肠中不表达,在其他组织(卵巢、肝脏、脾脏、脑、垂体、肌肉、心脏、肾脏)中微量表达。荧光定量PCR分析不同组织与不同时期性腺表达谱表明,雄鱼性腺中StAR基因的表达量显著高于雌、雄鱼其他各组织(P0.05),提示StAR基因对雄鱼精巢发育起重要作用。雄鱼不同时期表达谱分析结果显示,StAR基因在66天前的精巢中不表达,在150天时表达量急剧增加,至2龄时表达量最高,3龄时表达量下降,说明该基因在精巢发育成熟过程中起重要作用。原位杂交结果显示,StAR基因主要在雄鱼精巢的精子细胞中表达,而在雌鱼的卵巢中不表达。研究表明,StAR基因在半滑舌鳎精巢发育中发挥作用,且可能在精子形成中发挥重要作用。     

Distribution of a fish pathogen Listonella anguillarum in the Japanese flounder Paralichthys olivaceus hatchery

The present study was undertaken to investigate the distribution of Listonella anguillarum in a Japanese flounder (Paralichthys olivaceus) hatchery. A total of 2704 isolates were obtained from the developing fish, live diets and artificial feeds of Japanese flounder and their rearing water, 439 of which were identified as L. anguillarum by the combining incubation on thiosulfate-citrate-bile salt-sucrose (TCBS) agar at 35 °C overnight with polymerase chain reaction (PCR) detection for the VAH1 hemolysin gene. L. anguillarum was detected in all seven rotifer samples, with densities of 2.5 × 10³ to 4.6 × 10⁶ colony forming units (CFU) g^− 1. Both the analyzed samples of Nannochloropsis oculata contained this bacterium at densities of 1.6 × 10⁴ to 1.4 × 10⁵ CFU g^− 1. L. anguillarum was detected in only one of four samples of Artemia nauplii with a density of 4.8 × 10⁵ CFU g^− 1 (35%) and it was not detected in the two analyzed artificial feed samples. L. anguillarum was detected in 11 of 18 specimens of larval and juvenile Japanese flounder at densities of 5.0 × 10¹ to 7.4 × 10⁵ CFU g^− 1, while it was not detected in the two analyzed egg specimens of Japanese flounder. These results indicate that L. anguillarum associated with the developing Japanese flounder is likely derived from rearing water and live diets such as rotifers. Further, it is strongly suggested that L. anguillarum is a transient bacterium of the intestinal microflora for the Japanese flounder but is a permanently indigenous one for the Japanese flounder hatcheries.