亚硝酸盐和硫化物对克氏原螯虾幼虾的毒性效应研究

采用静水法生物测试,研究了亚硝酸盐(NO2--N)和硫化物(S2-)对克氏原螯虾(Procambarus clarkii)幼虾急性毒性效应。实验结果表明,克氏原螯虾幼虾的死亡率随着NO2--N和S2-浓度的升高和暴露时间的延长而显著上升。NO2--N对克氏原螯虾幼虾24、48、72、96h的半致死浓度(LC50)分别为108.09、90.08、73.02、69.74mg/L。S2-对克氏原螯虾幼虾24、48、72、96h的半致死浓度(LC50)分别为12.96、9.57、7.62、4.63mg/L。克氏原螯虾幼虾对NO2--N和S2-的安全浓度(SC)分别为6.97mg/L和0.46mg/L,为相应渔业水质标准的35倍和2.3倍,说明克氏原螯虾对NO2--N和S2-的毒性具有一定的耐受力,且对NO2--N的耐受能力强于S2-。     

克氏原螯虾大颚器的超微结构研究

克氏原螯虾的大颚器为一对,位于左右大颚的背面,大颚几丁质腱外侧基部。大颚器含丰富的血淋巴管和血窦,大颚器细胞围绕血窦成短束状排列,典型大颚器细胞超微结构最显著的特征;（１）线粒体和光面内质网广泛分布于胞质中,光面内质网明显分成小池状和小管状两种类型;（２）细胞质膜内陷并作不同程度的卷绕;（３）质膜外侧的基膜增厚,富含微丝。在泡状化的大颚器细胞中,光面内质网几乎消失,线粒体形态变异,胞核中的异染色质     

Growth performance and muscle composition response to reduced feeding levels in juvenile red swamp crayfish Procambarus clarkii (Girard, 1852)

Overfeeding in aquaculture can lead to suboptimal growth and increased production costs. Red swamp crayfish, Procambarus clarkii, is one of the most noteworthy species cultured in China, but little information is available on the optimal feeding levels of this species, especially in ponds cultured with macrophytes. In this study, we tested the effects of five different feeding levels (20%, 40%, 60%, 80% and 100% satiation) of an artificial diet on growth performance and muscle composition of juvenile P. clarkii in 15 concrete ponds cultured with the macrophyte Hydrilla verticillata (three replicates for each treatment). The results showed that growth performance decreased only when feeding levels were below 60% satiation. Muscle composition analysis revealed that the moisture and ash contents of muscle did not vary significantly with feeding levels but that the lipid and protein contents of muscle significantly decreased when P. clarkii was fed to 40% satiation. Stable isotope analysis suggested a shift in crayfish diets to easily available H. verticillata when feeding levels decreased. With this study, we hope to encourage crayfish farmers to reduce feeding levels and increase natural food items such as macrophytes in cultured ponds to maximize crayfish yields and reduce production costs.     

贵州草海小龙虾虾青素提取条件及含量测定

以贵州草海自然水域捕获的新鲜小龙虾(Procambarus clarkii)为材料,采用单因素实验研究了提取溶液、料液比、提取温度、提取时间、提取次数对虾青素提取效果的影响,用分光光度法测定了草海小龙虾不同部位虾青素的含量。结果表明,以乙酸乙酯为提取溶液,料液比为1∶2(g∶mL),在60℃下提取2 h,重复提取两次,再此提取条件下虾壳中虾青素含量最高。在虾壳、虾肉和内脏三个部位中,虾壳中虾青素含量最高,虾肉和内脏中也含有少量虾青素,但是含量远低于虾壳中的含量,说明了小龙虾虾青素主要富集在虾壳中。     

Juvenile Procambarus clarkii farmed using biofloc technology or commercial feed in zero‐water exchange indoor tanks: A comparison of growth performance,enzyme activity and proximate composition

A 60‐day study comparing the growth performance; proximate composition and the digestive, immune and antioxidant enzyme activities of juvenile red swamp crayfish (Procambarus clarkii) reared using biofloc technology (the biofloc group) or a commercial diet (the control group) in zero‐water exchange indoor tanks was performed. A commercial diet was fed to both groups, and the daily feeding amount in the biofloc group was 40% less than that in the control group. Wheat bran and glucose were used in the biofloc group to ensure a C/N ratio >15 and the same feeding energy as that given to the control group. After 60 days of feeding, the final weight, weight gain and specific growth rate in the biofloc group were significantly higher than those in the control group. Furthermore, proximate composition analysis showed that the total hepatopancreatic lipid and ash contents of the biofloc group were significantly higher than those of the control group, and the intestinal and hepatopancreatic pepsin activities in crayfish in the biofloc group were higher than those in crayfish in the control group. Moreover, higher hepatopancreatic lipase and cellulase activities were observed for the biofloc group than for the control group. Biofloc technology promoted the health of the crayfish in terms of their immune and antioxidant enzyme activities. Based on the results of this study, biofloc technology is more effective than traditional commercial diets for the farming of juvenile crayfish.     

克氏原螯虾苗种规模化繁育技术

为解决克氏原螯虾苗种规模化供应短缺问题,以洪泽湖地区克氏原螯虾为研究对象,在研究、掌握本地区克氏原螯虾繁殖习性的基础上,设计并建设了由700 m2大棚产卵池和50 m2加温孵化温室及若干特制网箱组成的苗种规模化繁育设施.2007年9月分批次将16 443只成熟的克氏原螯虾亲虾放入大棚产卵池特制网箱,通过降低光照、微孔增氧、循环流水等措施,先后获得抱卵虾6 053只,平均抱卵率为45.7%;抱卵虾移入温室后,在控温、流水条件下孵化,获得了平均体长0.88 cm的稚虾76.9万尾,平均孵化率为81.1%.     

Oral vaccination trials with crayfish, Procambarus clarkii, to induce resistance to the white spot syndrome virus

The potential of oral vaccination against white spot syndrome virus (WSSV) in crayfish Procambarus clarkii was investigated. The protective effect of binary ethylenimine (BEI)-inactivated WSSV was tested by oral vaccination, followed by an oral challenge with WSSV. The crayfish fed with feed pellets coated with BEI-inactivated WSSV showed a resistance to WSSV on the seventh day post vaccination (dpv). The relative percentage survival values were 60%, 70% and 75% for the vaccinated once, twice and thrice with inactivated WSSV. Following an intramuscular injection experiment, no mortality was recorded in the inactivated WSSV group and the negative control at 17 days post challenge. The cumulative mortalities in the heated WSSV group and WSSV group were 100%. Shrimp that survived the WSSV challenge on the seventh day after cessation of oral vaccination were positive for the presence of WSSV by a polymerase chain reaction assay specific for WSSV. This result indicated that inactivated WSSV could protect crayfish against WSSV by oral delivery.     

温度、pH对克氏原螯虾血清酚氧化酶活力及稳定性的影响

以克氏原螯虾(Procam barus clarkii)为材料,研究温度、pH对其血清酚氧化酶活力及稳定性的影响。实验以L-dopa为反应底物,在试验设计的温度范围(20,30,40,50,60,70℃)内,测得酚氧化酶活力的最适温度为20℃,随温度升高酶活力迅速下降,该酶在20~40℃范围内表现出较高的热稳定性,而30℃时最稳定;该酶的最适pH 7.0,在pH 6.0和7.0的缓冲系统中表现出较强的稳定性。     

WSSV口服卵黄抗体的制备及在螯虾中的应用

将提纯的WSSV接种于蛋鸡后获得了高效价的IgY(卵黄抗体),与一定比例的保护剂混合后,瞬间喷雾干燥制成干粉其效价基本维持不变。在以螯虾为实验模型的攻毒及治疗试验结果表明:饲料中0.1%的IgY含量能在一定程度上延缓螯虾死亡时间,而0.2%的IgY含量则能够使螯虾的最终死亡率从100%降至30%左右。这表明WSSV特异性IgY制剂是安全有效的抗WSSV感染的的新型生物制剂。     

克氏原螯虾对3种不同生长型沉水植物清水态系统的影响

鉴于克氏原螯虾（Procambarus clarkii）是目前全球入侵最广、对淡水生态系统最具破坏性的物种之一,探究其对沉水植物清水态系统的影响,有助于防范克氏原螯虾入侵给浅水湖泊带来的生态风险。通过受控实验,研究了克氏原螯虾对直立型沉水植物轮叶黑藻（Hydrilla verticillata）、冠层型沉水植物穗花狐尾藻（Myriophyllum spicatum）和莲座型沉水植物密刺苦草（Vallisneria denseserrulata）的影响以及不同植物培养系统对理化因子的响应变化。结果显示,直立型轮叶黑藻相对生物减少量（60.5%）大于冠层型穗花狐尾藻（45.7%）和莲座型密刺苦草（39.0%）;克氏原螯虾进入后导致3种生长型沉水植物清水态系统的总悬浮物浓度、叶绿素a和营养盐均极显著增高（P<0.01）。研究表明,水生态系统中的克氏原螯虾会直接降低沉水植物生物量,并扰动底泥增加水体的悬浮物、叶绿素a和营养盐浓度,导致水体由清水态向浊水态转变,也会通过直接牧食或扰动破坏,降低沉水植物生物量,最终影响草型清水态系统的稳定性。