A3α肽聚糖对凡纳对虾幼体生长及抗病毒感染力的影响

用含不同量的A3α肽聚糖(PG)(0.005%、0.01%、0.1%)的幼体饵料投喂凡纳对虾幼体,另在育苗水体中添加不同水平(0.005mg·mL-1、0.01mg·mL-1、0.05mg·mL-1)PG浸浴并以投喂不添加PG的幼体饵料的实验组作为对照,另设投喂活饵的实验组作参考,分别考察Z1-M1期、M1-PL1期、Z1-PL1期幼体的成活率,M1期、PL1期幼体体长,PL1期幼体体重,另外,PL1期仔虾经7d饲养后,检测体内酚氧化酶(PO)活性,并用白斑综合症病毒(WSSV)料投喂感染。结果显示:与投喂不添加PG幼体饵料组相比,在Z1-M1期,活饵组、0.01%PG添加量的幼体饵料组、0.005mg·mL-1PG的浸浴组幼体的成活率有极显著(P<0.01)提高,而在Z1-PL1、M1-PL1期,各实验组除0.05mg·mL-1浸浴组外均有极显著地(P<0.01)提高;各实验组除0.01mg·mL-1、0.05mg·mL-1PG浸浴组外,M1期幼体体长、PL1期幼体体重也有显著(P<0.01)增长,且各实验组PL1期幼体都有极显著(P<0.01)增长;各实验组仔虾PO活力均有极显著(P<0.01)提高;各实验组除0.1%PG添加量的幼体饵料组外,感染WSSV后仔虾的存活率有不同程度地提高。

Effects of A3α peptidoglycan on growth of Penaeus vannamei larvae and resistance to virus

The cultivation of larvae is the first and foremost step in shrimp farming which is directly related to the success or failure of the whole culture. Consequently, high quality of larvae is a guarantee to succeed in successive culture. There is now low survival rate in larvae cultivation of shrimp just because larvae are vulnerable to most pathogen, such as virus, bacteria, et al, which pose a menace to the production and quality of larvae. The use of immunostimulants to facilitate larvae culture is widely promising. Recently, more and more evidences show that peptidoglycan(PG) is helpful for aquatic animals to enhance the immunocompetence and resistance to pathogens, nevertheless, no evidence is given to shrimp larvae. In this experiment, Penaeus vannamei larvae were fed with steamed egg custard with the supplement of 0.005%,0.01%,0.1% peptidoglycan(PG),and immersed in the seawater containing 0.005 mg/mL, 0.01 mg/mL, 0.05 mg/mL PG, while larvae fed with egg custard without PG were designed as the control. The other larvae fed with living diet during the experiment are included, too. The survival rates of larvae at stages Z1-M1, stages M1-PL1, stages Z1-PL1,and the body length of larvae at stages M1 and PL1 and the body weight of larvae at stage PL1 were evaluated, respectively. The activities of phenoloxdase(PO) were tested after PL1 were fed for another 7 d, then the larvae were challenged by white spot syndrome virus (WSSV). The results showed that compared with control, the survival rates of larvae in the other groups (fed with living diet and steamed egg custard with 0.01% PG supplement, immersed in the seawater containing 0.005 mg/mL PG) at stage Z1-M1 increased significantly(P<0.01); at stages of Z1-PL1 and M1-PL1,only the group immersed in the seawater containing 0.05 mg/mL PG did not show higher(P>0.01) survival rate, and all other groups showed much higher(P<0.01) survival rates; both body length of larvae at stage M1 and body weight of larvae at stage PL1 of the groups immersed in the seawater containing 0.01 mg/mL and 0.05 mg/mL PG did not increase significantly (P(>0.01)), while other groups increased significantly (P<0.01); the body length of larvae at stage PL1 increased significantly (P<0.01) too; the larvae of all groups showed much higher (P<0.01) PO activities; the group fed with steamed egg custard with a supplement of 0.1% PG challenged by WSSV did not show higher(P>0.01) survival rates, and all other groups challenged by WSSV showed higher(P<0.01) survival rates.