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为了解Mo6+的毒性积累和毒性机制,以及草鱼(Ctenopharyngodon idellus)的健康饲养提供参考,采用静水测试法研究了养殖水体中不同质量浓度Mo6+ (0 mg/L,15.33 mg/L,30.67 mg/L,61.33 mg/L,122.66 mg/L,245.32 mg/L)对草鱼幼鱼鳃、肝胰脏及心脏组织结构的影响.结果表明:Mo6+对草鱼24 h、48 h和96 h的半数致死浓度(LC50)分别为1.553 6 mg/L、1.000 7 mg/L和0.000 1 mg/L,由公式(48 h LC50×0.3)/(24 h LC50/48 h LC50)2和96 h LC50×0.1计算的安全质量浓度分别为0.543 mg/L和0.001 mg/L.中毒后草鱼鳃的鳃小片卷曲、变短,呼吸上皮细胞水肿变性并部分脱落,细胞开始出现破裂,细胞液溢出,细胞核出现轻微的聚集状况;肝脏的肝细胞出现严重水样变性,并且血窦扩张,伴随细胞溶解、浑浊变性和轮廓模糊,形成局部的点状病灶;心脏的肌纤维细胞体积增大,单位视野内细胞数变少,细胞核形态异常,以及局部的细胞空泡变性,但出现少量细胞核偏移和密集并且细胞轮廓模糊,肌纤维有轻微断裂现象.     

低盐度和不同硫酸铜浓度对银鲳鳃离子调节酶和肝抗氧化功能的影响

开展银鲳(Pampus argenteus)试养海域的盐度易随气候降低, 且受到一定程度Cu等重金属污染, 研究低盐条件下硫酸铜对银鲳的影响十分必要。本实验首先进行银鲳幼鱼低盐度适应, 将盐度以4的幅度从24逐步降低至12。稳定后进行硫酸铜胁迫, 在盐度12下CuSO₄·5H₂O浓度梯度设为0、0.1、0.3、0.5 mg·L^–1, 盐度24下CuSO₄·5H₂O浓度梯度设为0、0.5 mg·L^–1, 胁迫持续144 h。通过检测两种鳃离子调节酶: Na⁺/K⁺-ATP酶(NKA)和V-H⁺-ATP酶(VHA), 以及3种肝抗氧化活性物质－还原型谷胱甘肽(GSH)、超氧化物歧化酶(SOD)和过氧化氢酶(CAT), 探究低盐条件下铜离子对银鲳幼鱼上述指标的影响。结果显示, 盐度逐步降低后, NKA与VHA活力呈上升后下降的变化, 之后NKA活力随硫酸铜浓度增加而减弱; VHA活力加入硫酸铜后都出现显著下降, 其中CuSO₄·5H₂O 0.3 mg·L^–1与0.5 mg·L^–1组在72 h时下降更为明显; 盐度24硫酸铜组NKA和VHA活力都在24 h时增强而后减弱。GSH含量和SOD活力在盐度降低时出现跃升, CAT活力则呈波动变化, 加入硫酸铜后, 0.3 mg·L^–1与0.5 mg·L^–1组GSH含量持续下降后显著上升而后回落; 各硫酸铜组SOD活力都出现增强后回落的变化; 0.3 mg·L^–1与0.5 mg·L^–1组CAT活力在72 h有显著增强。本实验表明, 铜离子对NKA与VHA有抑制作用, 盐度降低时其作用更强; GSH、SOD和CAT的变化能反映低盐度和铜离子对银鲳的伤害程度。银鲳对水体铜离子有一定的抗性, 但在盐度降低等环境变化时, 应当密切注意水体中铜等重金属浓度。

     

Dietary potassium requirement of juvenile grass carp (Ctenopharyngodon idella Val.) based on growth and tissue potassium content

A growth trial was conducted to estimate the optimum concentration of dietary potassium (K) for grass carp (Ctenopharyngodon idella). Triplicate groups of grass carp (3.96 ± 0.06 g) were fed diets containing graded levels (0.87, 2.90, 5.37, 7.54, 9.87 and 12.4 g kg^?1) of K for 8 weeks. Final body weight, weight gain and feed efficiency and gill Na⁺‐K⁺ ATPase activity were highest in fish fed with 9.87 g kg^?1 dietary K and lowest in fish fed the basal diet (P < 0.05). The K contents in whole body and muscle were linearly increased up to the 9.87 g kg^?1 dietary K and then levelled off beyond this level, whereas in scales and vertebrae up to the 7.54 g kg^?1 dietary K (P < 0.05). However, dietary K levels had no significant effect on ash, Ca, P and Mg contents in whole body, scales, vertebrae or muscle. Analysis using polynomial regression of weight gain and gill Na⁺‐K⁺ ATPase activity and using the broken‐line regression of whole body K concentrations indicated that the adequate dietary K concentration for grass carp is about 9.45–9.99 g kg^?1 diet.     

Recovery of Bacillus mycoides,B. pseudomycoides and Aeromonas hydrophila from common carp (Cyprinus carpio) and rainbow trout (Oncorhynchus mykiss) with gill disease

During a 3‐month period from June to the end of August 2016, ~5% mortalities were observed in a farm with rainbow trout (Oncorhynchus mykiss Walbaum) and one farm of common carp (Cyprinus carpio L.) in Bulgaria. The disease was manifested by gill ulcers/rot, asphyxiation and bloody ascites. Aeromonas hydrophila was isolated from the internal organs of all the diseased fish. Bacillus mycoides or B. pseudomycoides were recovered from the gill lesions on diseased carp and rainbow trout, respectively, with identification achieved by conventional phenotyping and by sequencing of the 16S rRNA gene. In vivo experiments confirmed that all three organisms were pathogenic to rainbow trout.     

镉对背角无齿蚌鳃和肝脏氧化损伤的影响

为了探明镉(Cd~(2+))对背角无齿蚌(Anodonta woodiana woodiana)鳃和肝脏的氧化损伤,根据Cd~(2+)96 h的半致死浓度,设置了5个处理组(4.22、8.43、16.86、33.72、67.45 mg·L~(-1))和1个空白对照组,分别处理24、48、72、96 h,通过实验测定其鳃与肝脏中过氧化氢(Hydrogen peroxide,H_2O_2)含量、抗超氧阴离子能力(Superoxide anion,O_2~-·)、抑制羟自由基能力(Hydroxyl radical,·OH)及总抗氧化能力(Total antioxidant capacity,T-AOC)。结果显示,在同一时间,与对照组相比,背角无齿蚌鳃和肝脏中H_2O_2含量整体表现为极显著性升高(P0.01);鳃抑制·OH能力出现极显著性降低(P0.01),肝脏抑制·OH无明显变化;鳃和肝脏抗O_2~-·能力均呈极显著性降低(P0.01);鳃和肝脏T-AOC呈极显著性升高(P0.01)。研究表明,肝脏作为背角无齿蚌的解毒器官,对外源Cd~(2+)的污染较为敏感,可以作为水体中镉污染监测的靶器官;鳃和肝脏抗O_2~-·能力均呈降低趋势,说明O_2~-·可能是镉致使背角无齿蚌氧化损伤的首要因素,可以作为水体镉污染监测的生物指标。     

运输胁迫对四指马鲅幼鱼肝脏、鳃和脾脏组织结构的影响

[目的]探究运输胁迫对四指马鲅(Eleutheronema tetradactylum)幼鱼肝脏、鳃、脾脏组织结构的影响,提高种苗运输存活率,为其规模化养殖提供技术支持.[方法]以四指马鲅幼鱼为研究对象,分别设对照组(未运输)、混合组(运输,同时添加抗应激混合物)和空白组(运输,不添加任何抗应激剂),抗应激剂为维生素C∶谷氨酰胺=1∶1.混合组和空白组幼鱼经6h运输后分别取样(肝脏、鳃和脾脏),经石蜡切片和HE染色,显微镜下观察测定肝脏、鳃和脾脏的细胞形态、组织结构、生活及生理状态.[结果]对照组幼鱼表现正常,未出现死亡现象,混合组幼鱼的累计死亡率为12.5%,空白组的累计死亡达27.5%.对照组幼鱼的各组织均呈正常形态;混合组幼鱼的肝脏部分区域细胞排列疏松,肝小板结构不清晰;空白组幼鱼的肝脏组织整体失去固有形态,肝小板结构消失不见,大部分细胞核变性呈椭圆形或纺锤形.混合组幼鱼的鳃丝排列混乱,少数鳃小片末端或整体肿胀,血窦内红细胞出现部分堆积现象,线粒体丰富细胞体积变大;空白组的鳃小片整体肿胀,血窦加粗,部分鳃小片因红细胞过多而胀破,线粒体丰富细胞体积变大且数量增多.混合组幼鱼的脾脏白髓区域相对增大,黑色素—巨噬细胞中心数量及大小均有所增加;空白组幼鱼的脾脏组织红髓区域占据大部分,白髓区域相对较少,呈零散分布,巨噬细胞中心减小.[结论]运输胁迫导致四指马鲅幼鱼肝脏、鳃及脾脏组织损伤,抗应激剂混合物虽然在一定程度上起到缓解作用,但并不能完全消除.     

Histopathological and behaviour effects of formaldehyde treatment in juvenile mullet,Mugil liza (Valenciennes)

Considerable losses may be related to diseases caused by parasites in aquaculture. Formaldehyde (37% gas dissolved in water) is an effective chemotherapeutic, widely used to control ectoparasites in fish. However, for many species of fish used in aquaculture, the control of external parasites and the deleterious effects of formaldehyde in short‐term baths are still uncertain. In order to clarify some gaps, 1 h‐prophylactic baths (67.5, 135, 270, 405 and 540 mg L^?1 formaldehyde in triplicate) were performed in juvenile mullet, Mugil liza (Valenciennes). Results showed that prophylactic baths of 135 mg L^?1 formaldehyde by 1 h did not cause death in tested mullets. At this concentration, histopathologies were mild and fish survival was high. However, fish exposed to increasing concentrations of formaldehyde presented severe histopathologies in the gills besides behavioural and morphological alterations. The histopathological and behavioural implications of formaldehyde use in aquaculture are discussed.     

稀有鮈鲫鳃的组织结构及水体镉暴露对其影响

运用石蜡切片技术和扫描电镜技术对稀有鮈鲫(Gobiocypris rarus)鳃结构进行观察,并采用浓度为2 mg/L的Cd Cl_2水溶液对稀有鮈鲫进行急性毒理实验。结果显示:稀有鮈鲫具4对鳃,由鳃耙、鳃弓、鳃丝及鳃小片组成。鳃的各个部位表面均有上皮细胞覆盖;鳃耙和鳃弓具味蕾,鳃弓上还具不同类型的黏液细胞;相邻鳃小片的上皮细胞间也分布有黏液细胞,在鳃小片基部有氯细胞着生。鳃丝表面有不规则凹陷和微嵴,具沟、坑、孔等结构;鳃小片两面均呈凹凸状。在2 mg/L的Cd Cl_2水溶液暴露下,鳃受到损伤,发生鳃小片充血呈球状,鳃上皮水肿、脱落,黏液细胞增多等现象;并随时间延长受损程度加重。     

凡纳滨对虾鳃细胞膜IHHNV衣壳蛋白受体的筛选

对虾传染性皮下及造血组织坏死病(IHHN)为对虾主要病毒病之一,近些年,在全球范围内广泛流行并造成严重的经济损失。目前,在流行病学和诊断方面受到重视,但其致病机理鲜有报道。本研究首先构建了IHHNV CP原核表达载体,纯化CP蛋白并制备多抗,抗体效价达到1︰51200;利用匀浆、超速离心方法分离未感染IHHNV的凡纳滨对虾(Litopenaeus vannamei)鳃细胞膜蛋白;用VOPBA和HIS PULL–DOWN方法筛选凡纳滨对虾鳃细胞膜IHHNV CP受体,分别将疑似的蛋白条带进行LC-MS/MS分析。结果表明,信号转导与转录激活因子(STAT)、热休克蛋白90(HSP 90)、酚氧化酶原2型、Na+/K+-ATP酶α亚基4种蛋白能与IHHNV衣壳蛋白产生相互作用,并具有多种生物学活性,可能参与病毒的入侵及细胞病变的产生。其具体作用有待深入研究。