塔里木河流域发现河川沙塘鳢

2006年10月28日,作者在新疆阿拉尔市塔里木大学集贸市场采购到1尾活的属于塘鳢科小鱼;2007年6月15日,塔里木大学文理学院学生在新疆生产建设兵团农一师十二团八连(属阿拉尔市管辖)塔里木河灌溉沟渠中抓获一批小杂鱼,从中获得6尾与上述小鱼同样的鱼;     

河川沙塘鳢胚胎、仔鱼发育过程中 蛋白质含量及氨基酸库的变化

采用生物化学方法测定和分析了河川沙塘鳢(Odontobutis potamophila)胚胎、仔鱼发育过程中蛋白质含量及氨基酸的组成和含量。结果显示,从受精卵开始到孵出后8 d饥饿仔鱼的整个胚胎和仔鱼发育过程中,其总蛋白和总氨基酸含量均呈下降趋势;总的必需氨基酸含量和总的非必需氨基酸含量也一样都呈现出下降趋势;平均含量最高的氨基酸是亮氨酸Leu、赖氨酸Lys、谷氨酸Glu和天冬氨酸Asp。与总氨基酸库相反,游离氨基酸库却呈现出随着发育的进行而不断增长的趋势,这种增长趋势也反映在游离的必需氨基酸和游离的非必需氨基酸含量的变化上,并且平均含量最高的游离氨基酸是赖氨酸Lys、亮氨酸Leu、脯氨酸Pro和谷氨酸Glu。整个发育过程中,游离氨基酸的含量仅占总氨基酸库的很小一部分(在受精卵,仅占0.16%)。由于总蛋白和总氨基酸含量在发育过程中均呈下降趋势,而游离氨基酸含量呈增长趋势,由此可知,在整个胚胎发生过程中,其卵黄蛋白的水解速度大于胚体同化和异化作用对氨基酸的消耗速度。     

苯并(a)芘与壬基酚对河川沙塘鳢的联合毒性研究

为探究环境内分泌干扰物联合毒性对鱼类的影响,选取苯并芘(benzo[a]pyrene,BaP)及千幕酚(4-nonlyphenol,NP)对河川沙塘鳢Odontobutis potamophila进行单独和联合毒性研究.研究了NP和BaP对河川沙塘鳢血清雌二醇(E2)、卵黄蛋白原(Vtg)、血清谷草转氨酶(GOT)以及肝脏7-乙氧基-3-异吩咏唑酮-脱乙基酶(7-ethoxyresoufin-O-deethylase,EROD)和超氧化物岐化酶(SOD)的影响.结果 表明,BaP单一暴露时,随着BaP剂量浓度的升高雌鱼血清E2含量下降,肝脏EROD活性升高;25 mg/kg BaP试验组雌鱼肝脏EROD活性显著高十对照组;肝脏SOD和血清GOT活性与对照无筹异;NP和BaP联合暴露中,200 mg/kg NP+10 mg/kg BaP、200 mg/kg NP+2 mg/kg BaP试验组雄性个体血清Vtg平均含量比200 mg/kg NP组低50%左右,而血清E2含最显著高于对照组,肝脏EROD酶活性、血清GOT活性变化与BaP剂量浓度呈正相关,而肝脏SOD酶活性则与BaP剂量浓度呈负相关;200 mg/kg NP+25 mg/kg BaP试验组肝脏SOD活性显著低于对照组,而血清GOT活性则显著高于对照组.显示NP和BaP联合作用时BaP可拮抗NP对雄鱼Vtg的诱导效应;200 mg/kg NP+2 mg/kg BaP可导致河川沙塘鳢肝脏肝细胞损伤.     

河川沙塘鳢孵化腺的发生及孵化酶的分泌

利用光学显微镜和扫描电镜观察了河川沙塘鳢Odontobutis potamophila(Gnther)孵化腺的发生及孵化酶的分泌过程。河川沙塘鳢的孵化腺为单层细胞腺体,发生于外胚层。孵化腺(Hatching gland,HG)最早发生自眼晶体形成期的胚胎,初发生时孵化腺细胞(Hatching gland cells,HGCs)分布于头部腹面及其与卵黄囊连接处。随着胚胎的发育,HG仍以单层细胞分布于胚体和卵黄囊的外表面,HGCs数量急剧增多,细胞体积增大,分布范围更加广泛。至眼黑色素出现期的胚胎,HGCs的数量达到大约900-1200个,广泛分布于胚胎头部两侧、头部腹面及其与卵黄囊连接处、卵黄囊的前腹面。HGCs大多呈椭圆形,短径为5-8μm,长径为7-12μm,在HE染色中呈粉红色。至孵化前期时,孵化酶颗粒自HGCs顶部的开口分泌出来,分泌颗粒呈圆球形,直径为0.5-1.0μm,有的以单体的形式存在,有的粘结成团。孵化酶进入卵周液,对卵膜内层进行消化和降解,使胚胎破膜而出。孵化后2d,HGCs便从表皮中消失。     

云斑尖塘鳢仔鱼摄食节律的研究

对自然光照条件下云斑尖塘鳢仔鱼的昼夜摄食节律和在夜间增加不同强度外光源条件下仔鱼的摄食发生率进行了研究。结果表明,云斑尖塘鳢仔鱼具有明显的昼夜摄食节律,晚上摄食发生率是著高于白天,其摄食主要集中在光线较弱的16:00～00:00;5日龄仔鱼在100～500Lx,8日龄和12日龄仔鱼在10～100Lx光照条件下的摄食发生率要明显高于黑暗或更高光照条件下的摄食发生率。     

河川沙塘鳢繁殖期与非繁殖期种群形态差异、雌雄个体差异及遗传多样性分析

本研究利用传统形态性状测量及框架性状分析方法研究了江苏省河川沙塘鳢繁殖期与非繁殖期种群形态特征及雌雄个体差异。结果显示,河川沙塘鳢存在形态特征的季节差异,繁殖期个体拥有相对较大的眼径、眼间距,推测与食物资源的季节性变化有关;另外,背鳍前距和胸鳍基长较长,可能因性腺发育饱满导致该时期个体腹腔容积变大。在两性特征中,两性异形指数为-0.013,表明雄鱼个体较大。雄性在尾柄高、尾鳍长等方面显著大于雌性,以此来增加竞争能力以及对后代的保护能力。雌性个体具有较大的腹腔容量,增加了繁殖输出,提高繁殖适合度。另外,本研究基于线粒体cytb基因,84个个体共识别出17个单倍型,整体表现出具有较高的遗传多样性（h=0.892,π=0.508%）,表明江苏省河川沙塘鳢群体存在丰富的线粒体DNA多态性。     

云斑尖塘鳢胚胎和早期仔鱼的发育

对云斑尖塘鳢(Oxyeleotris marmoratus)胚胎和早期仔鱼的发育进行了观察,详细描述了各发育阶段的形态特征。在28℃定水温条件下,云斑尖塘鳢的胚胎发育历时80h 30min,可分为24个发育分期。在整个发育过程中,眼、耳囊、心脏、消化道、肾脏、鳔、胸鳍和尾鳍等得到了优先发育。     

线纹尖塘鳢仔、稚鱼的形态发育

对池养条件下线纹尖塘鳢(Oxyeleotris lineolatus)的胚后发育进行定期观察,胚后发育大致可分为前期仔鱼、后期仔鱼、稚鱼和幼成鱼期。观察发现,线纹尖塘鳢的初孵仔鱼个体较小,仅2.875mm,前期仔鱼,包括混合营养仔鱼期,时间短,仅为5d,属较早建立起外源性营养摄食机制的鱼类;器官发育主要在后期仔鱼阶段完成;鳞的出现和鳞被形成在稚鱼发育阶段完成;在池塘自然水温26~30℃条件下,从初孵仔鱼到稚鱼发育期完成历时43~44d。     

褐菖鲉的视觉器官发育

为研究褐菖鲉（Sebastiscus marmoratus）视觉器官发育与生态习性及摄食行为之间的关系,用组织学方法对人工培育条件下的褐菖鲉仔、稚鱼的视觉器官发育特征进行了详细观察。结果表明,褐菖鲉为卵胎生鱼类,其视觉器官的分化速度较一般鱼类快,从母体产出时,仔鱼视网膜神经细胞层和原始晶状体已形成;1日龄仔鱼的视网膜分化为6层,晶状体出现纤维化,直径约72 μm,仔鱼开始具有一定趋光性;2日龄仔鱼视网膜分化完成,可见10层结构,巩膜出现,与仔鱼开口摄食相适应,游泳能力增强;5 ~ 7日龄晶状体直径达99 μm,晶状囊形成;17日龄,仔鱼角膜结构分化完成,脉络膜趋于完善;37日龄稚鱼的视觉器官各部分已经发育完全。     

河川沙塘鳢对猎物种类和大小选择性研究

为了明确河川沙塘鳢(Odontobutis potamophila Günther)养殖宜投喂饵料生物的种类和规格, 通过室内外试验研究了沙塘鳢对生活习性不同8种饵料生物的种类选择, 对不同规格赤眼鳟(Squaliobarbus curriculus Richardson)的选择, 以及其不同生长阶段对饵料鱼大小的选择。研究结果表明, 沙塘鳢对麦鲮(Cirrhinus mrigala Hamilton)的选择指数显著大于其对剩余7种饵料生物的选择指数; 在无仿真水草条件下, 沙塘鳢对小规格饵料生物的选择指数显著大于对大、中规格饵料生物的选择指数; 在仿真水草条件下, 沙塘鳢对小规格饵料生物的选择指数显著大于其对大规格饵料生物的选择指数。在不同生长阶段中, 沙塘鳢全长与其捕食的饵料鱼全长呈现正相关关系; 沙塘鳢捕食的饵料鱼PPR值为0.23—0.73, 均值为0.49±0.1(均值±标准差); 随沙塘鳢规格的增加其捕食饵料鱼的PPR值降低, 捕食饵料鱼规格分布小于环境中饵料鱼规格分布。综上, 沙塘鳢养殖宜投喂饵料鱼麦鲮, 饵料鱼PPR值宜为0.38—0.6。     

仿生态养殖技术在淡水养殖中的应用

文章对河川沙塘鳢(Odontobutis potamophila)繁殖过程中鱼巢选择、鱼卵孵化、产后亲本和苗种生长情况及同类残食进行了相关研究。结果显示, 河川沙塘鳢亲本对鱼巢的选择为池塘四周中层水体的鱼巢; 苗种最佳孵化方式为孵化缸带雄鱼孵化, 该种方式水霉发生率最低(29.13%)。通过对亲本池与苗种池河川沙塘鳢生长和繁殖力的周年监测, 发现鱼苗9月特定生长率最大, 10月明显下降, 冬季接近于0, 至次年繁殖期降为负值, 繁殖过后迅速回升; 亲本特定生长率变化趋势与苗种相似, 不同的是亲本在10月特定生长率最大。鱼苗生长至次年能完成性腺发育并参与繁殖, 绝对繁殖力为(1157±666)粒, 显著低于亲本池(2570±943)粒, 但相对繁殖力[(112.78±19.97)粒/g]显著高于亲本池[(89.05±26.25)粒/g]。此外, 文章基于养殖过程中出现同类残食现象, 构建了预测模型TLprey=0.701TLcannibal –8.043, 提出苗种培育的分级培育技术, 建议在集约化养殖中将全长比值相差1.55倍的个体分开培育。文章丰富了河川沙塘鳢人工繁育技术。

     

Sall3 plays essential roles in horizontal cell maturation through regulation of neurofilament expression levels

The region-specific homeotic gene spalt (sal) gene plays a critical role in Drosophila development. The mammalian Sal homologous genes contain four members, and Sall3 is mainly expressed in horizontal cells. In the developing retinas of Sall3 knockout (KO) mice until around birth, horizontal precursor cells developed with comparable numbers and position; the horizontal cell marker NF160 was expressed weakly and neurite-like structure had once formed. Since Sall3-KO mice die at postnatal day 1, subsequent retinal development was examined by in vitro retinal explant culture. In the Sall3-KO retina culture, the expression of NF160 was abrogated, and neurite extension was not observed. Furthermore, Sall3-KO horizontal precursors were initially localized at the appropriate horizontal positions, but eventually moved to an abnormal site in the outer nuclear layer. Overexpression of Sall3 in retinal progenitors did not induce differentiation of retinal progenitor cells into the horizontal cell-fate, but enhanced NF160 expression and neurite extension. In addition, differentiation into Müller glia was promoted, and rod cells were severely suppressed without perturbing proliferation. In conclusion, Sall3 may not be involved in horizontal cell-fate determination, but rather functions to instruct terminal differentiation of horizontal cells and to maintain NF160 expression.     

Acetylcholine and Dopamine Promote the Production of Platelet Activating Factor in Immature Cells of Chick Embryonic Retina

We have previously shown that platelet-activating factor (PAF), a naturally occurring lipid mediator of cell-to-cell communication, was produced by 3-day-old chick retina stimulated with acetylcholine (ACh) and dopamine (DA), but not with other neurotransmitters. ACh and DA stimulated PAF synthesis via a dithiothreitol (DTT)-insensitive cholinephosphotransferase, without affecting the acetyltransferase pathway, which was stimulated only by the calcium ionophore A23187. Therefore, we attempted to study the effects of neurotransmitters on PAF production and on the activities of the DTT-insensitive cholinephosphotransferase and acetyltransferase in the developing chick embryo retina up to hatching. Our results show that PAF was produced already at 8 days of development, when retinal cells are still rather immature and ganglion and Mueller cells are the only differentiated cells. The stimulation of PAF production occurred with ACh and not with other neurotransmitters. In older stages, DA also stimulated PAF production, as already described in the chick after hatching. DTT-insensitive cholinephosphotransferase and acetyltransferase activities were present in 8-day-old embryos, the earliest stage analyzed. Both enzymatic activities increased with age; DTT-insensitive cholinephosphotransferase increased rapidly from day 12 up to day 18, whereas acetyltransferase activity increased linearly up to the time of hatching. To promote PAF production, ACh and DA activate DTT-insensitive cholinephosphotransferase, but not acetyltransferase.(ABSTRACT TRUNCATED AT 250 WORDS)     

Robo2 is required for Slit-mediated intraretinal axon guidance

The developing optic pathway has proven one of the most informative model systems for studying mechanisms of axon guidance. The first step in this process is the directed extension of retinal ganglion cell (RGC) axons within the optic fibre layer (OFL) of the retina towards their exit point from the eye, the optic disc. Previously, we have shown that the inhibitory guidance molecules, Slit1 and Slit2, regulate two distinct aspects of intraretinal axon guidance in a region-specific manner. Using knockout mice, we have found that both of these guidance activities are mediated via Robo2. Of the four vertebrate Robos, only Robo1 and Robo2 are expressed by RGCs. In mice lacking robo1 intraretinal axon guidance occurs normally. However, in mice lacking robo2 RGC axons make qualitatively and quantitatively identical intraretinal pathfinding errors to those reported previously in Slit mutants. This demonstrates clearly that, as in other regions of the optic pathway, Robo2 is the major receptor required for intraretinal axon guidance. Furthermore, the results suggest strongly that redundancy with other guidance signals rather than different receptor utilisation is the most likely explanation for the regional specificity of Slit function during intraretinal axon pathfinding.