罗氏沼虾繁殖行为的再描述

2007年6～9月对采自孟加拉国库尔纳专区羌纳县布苏尔河原产地罗氏沼虾(Macrobrachium rosenbergii)的繁殖行为进行了观察研究。配合摄像机录像技术,重点观察并记录了野生罗氏沼虾生殖过程中的主要行为特征。本文所涉及的繁殖过程特指在人工操控条件下,自两性遭遇、识别至雌虾抱卵为止这段时间。选择体重在80.0g以上的雄虾、40.0g以上的雌虾分别在当地河堤外侧的池沼中驯化适应15d,然后,在室内水泥池中观察其繁殖行为。罗氏沼虾在繁殖过程中呈现的典型行为主要有:两性遭遇及识别,雄虾的占位,雌虾的蜕壳,雄虾俘获雌虾及其交媾前的守卫、交媾及精荚传递,雄虾交媾后的守卫及释放雌虾,雌虾产卵及抱卵。其中,雄虾的配偶守卫行为是有效地保证两性生殖成功的交配策略之一。     

恩诺沙星在罗氏沼虾体内的药物代谢动力学

应用反相高效液相色谱法(RP-HPLC)研究了恩诺沙星在罗氏沼虾(Macrobrachiumrosenbergii)体内的药物代谢动力学。实验结果表明,恩诺沙星在血淋巴、肝胰腺、肌肉中的平均回收率分别为86.54%±2.39%、85.43%±2.75%、95.01%±1.99%,其代谢产物环丙沙星在血淋巴、肝胰腺、肌肉中的平均回收率分别为94.34%±8.30%、75.17%±5.42%、80.42%±1.67%;恩诺沙星及其代谢产物环丙沙星在三种组织中的平均日内精密度分别为3.39%±0.53%和3.92%±1.24%,而日间精密度分别为5.11%±1.73%和5.28%±2.10%。恩诺沙星、环丙沙星的最低检测限分别为0.02μg/ml和0.01μg/ml。罗氏沼虾以10mg/kg虾体重剂量单次肌肉注射给药后,血液中药物浓度即刻达到峰值,并迅速向组织中分布。实验数据经MCPKP药动学软件分析,恩诺沙星在血淋巴中的主要药物代谢动力学参数为:t1/2α为0.581h、t1/2β为69.315h、Vd/F为7.230L/kg、CL/F为0.035L/h.kg、K12为0.01/h、K21为0.005/h、AUC为291.898μg/ml.h、Tmax为0.083h、Cmax为6.293μg/ml;恩诺沙星在肝胰腺、肌肉组织中主要药动学参数:t1/2α为1.941h、0.000h;t1/2β为70.732h、59.456h;AUC为308.07μg/ml.h、217.039μg/ml.h。三种组织中均能检测到恩诺沙星的活性代谢产物环丙沙星,但含量均处于较低水平,药物浓度-时间数据经MCPKP药动学软件处理后,不能用开放性一室模型或二室模型拟合。     

温度对罗氏沼虾亲虾代谢的影响

罗氏沼虾［Ｍａｃｒｏｂｒａｃｈｉｕｍｒｏｓｅｎｂｅｒｇｉ（ＤｅＭａｎ）］具有较高的经济价值,为当今世界上淡水虾类养殖的主要品种之一。由于我国没有天然的亲虾资源,人工育苗所需的亲虾靠养殖和人工越冬所得。因此研究亲虾的生理生态,可为提高人工繁殖技术的理论...     

注射光合细菌后罗氏沼虾血细胞组成的变化

以光合细菌作为刺激物,对罗氏沼虾进行肌肉注射,在注射后12、24、36、48、60h依次从罗氏沼虾心脏取血,用改良后的瑞氏染色法制成血涂片,光镜观察罗氏沼虾血细胞组成的变化.结果发现罗氏沼虾透明细胞在循环血细胞中所占地比例由正常状态下的66.62%略微下降至60%左右;36h左右所占比例急剧下降到30%左右;48h左右开始逐步回升;60h恢复至55%;接受刺激后的变化遵循缓慢下降、急剧下降、缓慢回升的过程.     

罗氏沼虾与克氏原螯虾血细胞的比较研究

对罗氏沼虾与克氏原螫虾血细胞的分类与组成进行了染色观察比较研究。根据染色后光镜下血细胞的核质比、颗粒的大小和数量等来对血细胞进行分类,罗氏沼虾与克氏原螯虾的血细胞均可分为透明细胞、半颗粒细胞和颗粒细胞三类;其血细胞浓度分别为1.02±0.21×10⁷ Ind·ml^-1和0.85±0.15×10⁷Ind·ml^-1。2种虾血细胞的颗粒形态存在显著差异;透明细胞、半颗粒细胞和颗粒细胞占血细胞总量的百分比在罗氏沼虾为21.3±6.3%,45.7±2.5%,33.0±6.8%:在克氏原螯虾为12.0±5.8%、49.5±5.1%和38.5±9.5%。     

三丁基锡(TBT)对罗氏沼虾的毒性效应

将罗氏沼虾(Macrobrachium rosenbergii)幼虾和成虾暴露在不同浓度的三丁基锡(tributyhin,TBT)溶液中,进行急性和慢性毒性实验,通过组织病理学观察研究TBT对罗氏沼虾的毒性效应。结果表明:TBT对罗氏沼虾幼虾和成虾的96h半致死浓度(96h LC50)分别为51和376μg.L-1,安全浓度(SC)分别为5.1和37.6μg.L-1;罗氏沼虾幼虾暴露在浓度分别为1.25、2.5和5μg.L-1的TBT溶液中30d后,其体重和体长均极显著低于对照组(P<0.05);罗氏沼虾成虾暴露在浓度分别为2、8和32μg.L-1的TBT溶液中30d后,生长速度虽未见明显差异,但鳃和肝胰脏组织结构均出现异常;TBT浓度高于8μg.L-1时,处理组鳃上皮细胞肿胀,支持细胞中的细胞核萎缩,鳃血窦中血细胞聚集,肝胰脏细胞肿大,出现空泡化,细胞中出现细小颗粒;TBT浓度达32μg.L-1时,罗氏沼虾肝胰脏细胞空泡化程度严重,细胞核消失,部分细胞解体并出现坏死区;表明一定剂量的TBT对罗氏沼虾的鳃和肝胰脏有明显的毒性效应。     

壬基酚和雌二醇干扰罗氏沼虾卵黄蛋白原VTG基因表达的效应

对刚孵化后的罗氏沼虾(Macrobrachium rosenbergii)亲虾用高低两个浓度的壬基酚(nonylphenol,NP,100μg/L和0·01μg/L)和雌二醇(estradiol,E2,1μg/L和0·01μg/L)进行浸泡处理,分别于3d和5d对罗氏沼虾肝胰腺和卵巢中卵黄蛋白原(vitellogenin,VTG)基因表达变化进行半定量分析。结果显示,NP和E2能够提高罗氏沼虾肝胰腺和卵巢中卵黄蛋白原VTG基因的表达。100μg/LNP对罗氏沼虾表现出雌激素效应,0·01μg/LNP作用效果不明显;而E2则在1μg/L和0·01μg/L两个浓度下均对罗氏沼虾有较强的雌激素效应。在100μg/LNP作用下,卵巢VTG表达量3d和5d均保持较高水平,无明显下降,其他实验组均是3dVTG基因表达量升高,5d后表达量较3d表达量有所降低。结果表明,与其他动物一样,NP对罗氏沼虾具有内分泌干扰作用。     

罗氏沼虾体内两种病毒颗粒的分离、纯化与核酸特性

从患肌肉白浊症状的罗氏沼虾幼苗体内分离纯化得到两种大小不同的病毒颗粒.这两种病毒颗粒均为对称的20面体结构,表面光滑,无囊膜,对氯仿不敏感.一种是直径为26nm～27nm的颗粒,在氯化铯中的密度为132g/cm3,病毒基因组含两段单链的RNA,分别为30kb和12kb,具有诺达病毒科成员的特征.一种是直径为14nm～16nm的颗粒,在氯化铯中的密度为133g/cm3,含有一段大小为09kb的单链RNA,拟为卫星病毒样颗粒或辅助病毒.     

He-Ne激光照射罗氏沼虾腹髓鞘神经纤维的电镜观察

用He Ne激光照射罗氏沼虾 (Macrobrachiumrosenbergii)的腹髓鞘神经纤维 ,结果表明 ,神经胶质细胞为不规则形 ,核的一端较大 ,另一端分叉 ,半包裹着轴突 ,呈蝴蝶形 ,核的横轴直径为 3 0 7μm ,轴突直径为 1 5 3 μm ;在髓鞘中普遍出现增厚的膜层结构 ,且膜层结构厚薄不一 ,具有高嗜锇性、电子密度大 ,正常的膜层厚度为 3 3 3 3nm ,增厚的膜层厚度可达 1 0 0nm。在两膜层之间存在着许多颗粒状物质。     

罗氏沼虾亲虾越冬池中不同基质上微生物群落多样性分析

【目的】了解罗氏沼虾亲虾越冬时循环养殖系统对水质的调控效果,探明其中微生物群落的作用。【方法】采集循环养殖系统运行88 d后的越冬池池水、池中人工水草(普通纤维膜)以及外置式生物滤器中的纳米纤维膜等3种不同基质上的微生物,利用DNA抽提、PCR扩增和定量以及高通量Mi Seq测序技术等对3种不同基质上的微生物进行16S r RNA基因序列V4-V5区的测定和分析,并根据测序得到的双端测序读长(Pair-end reads)进行质量控制和过滤,之后进行操作分类单元(OTU)聚类分析,并基于OTU对微生物群落的多样性指数和群落结构进行分析;每3-4 d对越冬池池水水质进行监测。【结果】养殖池塘的水质保持在良好的状态,其中氨氮和亚硝氮浓度控制在0.17±0.08 mg/L和0.28±0.15 mg/L;不同基质上的微生物组成和多样性都不相同。在3种基质上共检测并鉴定出细菌64种,隶属于9门64属,包括变形菌门(Proteobacteria)、放线菌门(Actinobacteria)、拟杆菌门(Bacteroidetes)、绿弯菌门(Chloroflexi)、厚壁菌门(Firmicutes)、浮霉菌门(Planctomycetes)、硝化螺旋菌门(Nitrospirae)、酸杆菌门(Acidobacteria)和绿菌门(Chlorobi)。从属水平上对3种基质上的细菌进行分析,发现养殖池水中含量最高的为丛毛单菌科下的一个未分类类群(Comamonadaceae_unclassified),其也是3种基质的共有优势类群;普通纤维膜上为Inhella,纳米纤维膜上则是小纺锤状菌属(Fusibacter)。3种基质上细菌群落多样性顺序为:纳米纤维膜普通纤维膜养殖池水。通过对亲虾越冬养殖全过程的水质监测,发现越冬期间亲虾池水质始终保持在良好状态,并且在循环水系统开启约40 d后水质达到了相对稳定的状态。【结论】通过在育苗池中悬挂人工水草,配合内含纳米纤维膜的外置式生物滤器,可使罗氏沼虾越冬亲虾池保持良好的水质。随着新型材料科学的发展,开发出适用于水产养殖业的滤料很有必要。     

An in vitro study of metal ion-induced lipid peroxidation in giant fresh water prawn Macrobrachium rosenbergii (de MAN)

Though metal ions are essential components of many cellular functions, their overexposure to organisms lead to oxidative stress through the formation of reactive oxygen species (ROS). Lipid peroxidation (LPX) is the oxidative deterioration of membrane lipids and considered as an index of oxidative stress. In the present study in vitro effect of various metals (FeCl₃, FeSO₄, CuSO₄, CdCl₂, and ZnSO₄) on the lipid peroxidation of gills and hepatopancreas of Giant Freshwater prawn, Macrobrachium rosenbergii, was compared with respect to dose and duration. The results clearly indicate that among all the metals investigated, FeCl₃ and CdCl₂ are more potent in inducing LPX, and FeCl₃ is more toxic than FeSO₄ in inducing LPX in the hepatopancreas. ZnSO₄ exhibits a moderate toxicity while CuSO₄ is least toxic and also inhibits LPX at higher concentration. Thus results of the present investigation suggest that all the metal ions investigated in the present study are capable of inducing oxidative stress in gills and hepatopancreas of M. rosenbergii     

养殖密度对史氏鲟稚鱼生长的影响

养殖密度对史氏鲟生长影响的研究结果表明 ,在养殖密度分别为 0 .2 32、0 .6 6 5、1.34 7和 2 .46 9kg·m-2 的流水环境中 ,各密度组的史氏鲟稚鱼的生长表现为不等速性 ,但生长离散没有加剧 .试验持续 2 8d后 ,各组的生长表现出显著差异 ,生长效率、特定生长率和日增重都随密度的增大而降低 ,而饵料转化率和净增重随密度的增大而增大 .特定生长率 (SGR)与养殖密度 (D)之间存在着显著的负相关     

Isolation and characterization of microsatellites in giant freshwater prawn Macrobrachium rosenbergii

Microsatellite loci were characterized in a freshwater prawn from enriched genomic library using six biotinylated probes: (AG)₁₀, (TG)₁₀, (CAA)₁₀, (CAG)₁₀, (GAT)₁₀ and (TAC)₁₀. Primers for DNA amplification were designed and synthesized for 20 loci. Ten loci were polymorphic with the number of alleles ranging from five to 17 alleles per locus and the observed heterozygosity ranging from 0.27 to 0.83 per locus. Developed microsatellite primers should prove useful for selective breeding programs and population genetic studies of freshwater prawn.     

不同形态型雄性罗氏沼虾的交配能力

从行为生态学角度,对采自孟加拉国库尔纳专区羌纳县布苏尔河罗氏沼虾原产地池塘种群中3种不同形态型雄虾的繁殖行为及交配能力进行了初步研究.结果表明：社群中蓝螯型（BC）、橙螯型(OC)和小型(SM)雄性罗氏沼虾的交配行为模式没有明显的区别,但BC、OC和SM雄虾在交媾前守卫、交媾及精荚传递和交媾后守卫3个典型行为中投入的时间存在明显差异.BC雄虾交媾前守卫、交媾及精荚传递用时明显比OC、SM雄虾短,而交媾后守卫用时明显比OC 、SM雄虾长.SM雄虾在交媾前守卫和精荚传递上投入的时间最长,而交媾后守卫用时最短.在雌虾体质量为雄虾体质量的80%,且♀∶♂为8∶1性比条件下,BC、OC和SM雄虾在120 h内平均交媾次数分别为4.6、2.2、1.3,BC雄虾具有较强的连续交媾能力.罗氏沼虾的交配能力与其体质量相关,雄、雌虾的体质量相匹配才能保证成功交媾.否则会出现“假交”现象.     

Microsatellite DNA markers in the giant freshwater prawn, Macrobrachium rosenbergii: a tool for genetic analysis

Eight microsatellite loci were identified and characterized in the commercially important giant freshwater prawn, Macrobrachium rosenbergii. The microsatellite loci were detected by the random screening for dinucleotide repeat units within a partial genomic library developed for the species with biotinylated probes (CA)(15) , (AT)(15) and (GA)(15) . All the eight loci were found to be polymorphic. The number of alleles and observed heterozygosities per locus ranged between three to 16 and 0.22 to 0.71, respectively. These microsatellite markers will be useful for the conservation and management of wild and cultured stocks and population genetic studies of freshwater prawn.     

Isolation and characterization of microsatellite loci in the Malaysian giant freshwater prawn, Macrobrachium rosenbergii

Eight single locus microsatellite markers were developed to characterize the Malaysian giant freshwater prawn, Macrobrachium rosenbergii. These microsatellites were isolated from an enriched genomic library contained by using a 5'-anchored polymerase chain reaction technique. Primers were designed to flank the repeat sequences and subsequently used to characterize 30 unrelated individuals of the giant freshwater prawn. The polymerase chain reaction amplification products of these eight microsatellite loci were polymorphic with the number of alleles ranging from two to 10 alleles per locus while the levels of heterozygosity ranged from 0.6333 to 0.8667.     

Chemical synthesis of N‐glycosylated insulin‐like androgenic gland factor from the freshwater prawn Macrobrachium rosenbergii

Crustacean insulin‐like androgenic gland factor (IAG) of Macrobrachium rosenbergii, a heterodimeric peptide having both four disulfide bonds and an N‐linked glycan, was synthesized by the combination of solid‐phase peptide synthesis and the regioselective disulfide formation reactions. The disulfide isomer of IAG could also be synthesized by the same manner. The conformational analysis of these peptides by circular dichroism (CD) spectral measurement indicated that the disulfide bond arrangement affected the peptide conformation in IAG. On the other hand, the N‐linked glycan attached at A chain showed no effect on CD spectra of IAG. This is the first report for the chemical synthesis of insulin‐like heterodimeric glycopeptide having three interchain disulfides, and the synthetic strategy shown here might be useful for the synthesis of other glycosylated four‐disulfide insulin‐like peptides.     

Lead toxicity at different life stages of the giant prawn (Macrobrachium rosenbergii,de Man): considerations of osmoregulatory capacity and histological changes in adult gills

This study evaluated the acute toxicity of lead in different life stages of the freshwater prawn Macrobrachium rosenbergii, determined the effect of sublethal Pb concentrations on osmoregulatory capacity (OC), measured the Pb level in gills, and investigated the effect of Pb on the structure of the gills of adult prawns. The 24-, 48-, and 96-h LC₅₀ values for Pb to M. rosenbergii increased progressively with increasing life stage, from post-larvae (PL), juvenile to adult. The 24- and 48-h LC₅₀ values for post-larvae ranged from 0.01- to 0.09-mg Pb/L. The 24-, 48-, and 96-h LC₅₀ values for Pb were lower at 12 ppt than those at 0 ppt for either the juveniles or the adults. At 12 ppt, the 96-h LC₅₀ values in PL11, juvenile and adult were 0.47-, 0.58-, and 2.03-mg Pb/L, respectively. Meanwhile, at 12 ppt, the 96-h LC₅₀ values in PL11, juvenile and adult were 0.63-, 4.44-, and 7.98-mg Pb/L, respectively. In adults, the OC values of controls and prawns exposed to 2- and 4-mg Pb/L at 0 ppt were not significantly different. The OC of prawns exposed to and 2-mg Pb/L at 12 ppt increased by 72 and 109% from the OC of the control prawns. At media 12 ppt, the OC value of prawns exposed to 1-mg Pb/L was significantly different from that of prawns exposed to 2-mg Pb/L. The concentrations of Pb in gill tissues increased significantly in Pb exposed prawns both at 0 and 12 ppt. The level of Pb in gills of prawns exposed to 2-mg Pb/L at 12 ppt was not significantly different from those exposed at 0 ppt. The severe toxic actions of Pb were noted in gills of prawns exposed in media 12 ppt. Hyperplasia and necrosis were observed in gill lamellae, resulting in abnormal gill tips after Pb exposure at media 12 ppt. Since the effect of Pb is more pronounced in higher salinity (12 ppt) than in freshwater (0 ppt) it is clear that aquaculture of M. rosenbergii should be conducted in freshwater ponds.     

Identification of lectin isoforms in juvenile freshwater prawns Macrobrachium rosenbergii (DeMan, 1879)

From the serum of juvenile freshwater prawns, we isolated by affinity chromatography on glutaraldehyde-fixed rat erythrocytes stroma, immobilized in Sephadex G-25, a sialic acid specific lectin of 9.6[emsp4 ]kDa per subunit. Comparative analysis against adult organisms purified lectin, by chromatofocusing, showed that the lectin from juvenile specimens is composed by four main isoforms with a pl of 4.2, 4.6, 5.1, and 5.6, whereas the lectin from adults is eluted at pH 4.2. The amino acid composition of the lectin obtained from adult and juvenile stages suggest identity, but the compositions are not identical since a higher content of carbohydrates was found in the lectin from younger organisms. The freshwater prawn lectin showed specificity toward N-acetylated amino sugar residues such as GlcNAc, GalNAc, Neu5Ac and Neu5,9Ac; but in juvenile organisms the lectin showed three times less hemagglutinating activity than the lectin from adults. Both lectins agglutinated rat, rabbit and chicken erythrocytes, indicating that Neu5,9Ac in specific O-glycosydically linked glycans seems to be relevant for the interaction of M. rosenbergii lectins with their specific cellular receptor. Our results suggest that the physicochemical characteristics of the lectin from the freshwater prawn are regulated through maturation.     

Impacts of stocking density on development and puberty attainment of replacement beef heifers

In all, 60 Angus×Hereford heifers were ranked by age and BW (210±2 days and 220±2 kg) on day 0, and assigned to: (a) one of three drylot pens (10×14 m pens; 10 heifers/pen) resulting in a stocking density of 14 m²/heifer (HIDENS; n=3), or (b) one of three pastures (25 ha pastures; 10 heifers/pasture), resulting in a stocking density of 25 000 m²/heifer (LOWDENS; n=3). Pastures were harvested for hay before the beginning of this experiment, and negligible forage was available for grazing to LOWDENS heifers during the experiment (days 0 to 182). All heifers received the same limited-fed diet, which averaged (dry matter basis) 4.0 kg/heifer daily of hay and 3.0 kg/heifer daily of a corn-based concentrate. Heifer shrunk BW was recorded after 16 h of feed and water withdrawal on days −3 and 183 for BW gain calculation. On day 0, heifers were fitted with a pedometer behind their right shoulder. Each week, pedometer results were recorded and blood samples were collected for puberty evaluation via plasma progesterone. Plasma samples collected on days 0, 28, 56, 84, 112, 140, 161 and 182 were also analyzed for cortisol concentrations. On days 0, 49, 98, 147 and 182, hair samples were collected from the tail switch for analysis of hair cortisol concentrations. On days 28, 102 and 175, blood samples were collected for whole blood RNA isolation and analysis of heat shock protein (HSP) 70 and HSP72 mRNA expression. Heifers from LOWDENS had more (P<0.01) steps/week compared with HIDENS. No treatment effects were detected (P=0.82) for heifer BW gain. Plasma cortisol concentrations were greater (P⩽0.05) in LOWDENS compared with HIDENS heifers on days 84, 140, 161 and 182 (treatment×day interaction; P<0.01). Hair cortisol concentrations were greater (P<0.01) in HIDENS compared with LOWDENS heifers beginning on day 98 (treatment×day interaction; P<0.01). Heifers from LOWDENS had greater (P=0.04) mean mRNA expression of HSP72, and tended (P=0.09) to have greater mean mRNA expression of HSP70 compared with HIDENS. Heifers from HIDENS experienced delayed puberty attainment and had less (P<0.01) proportion of pubertal heifers on day 182 compared with LOWDENS (treatment×day interaction; P<0.01). In summary, HIDENS altered heifer stress-related and physiological responses, and delayed puberty attainment compared with LOWDENS.