Lu Xia, Luan Sheng, Cao Baoxiang, Meng Xianhong, Sui Juan, Dai Ping, Luo Kun, Shi Xiaoli, Hao Dengchun, Han Guomin, Kong Jie
Key Laboratory of Sustainable Utilization of Marine Fisheries Resources, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, China.
Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
PLoS One. 2017 Mar 22;12(3):e0173835. doi: 10.1371/journal.pone.0173835. eCollection 2017.
Regarding the practical farming of Litopenaeus vannamei, the deterioration of water quality from intensive culture systems and environmental pollution is a common but troublesome problem in the cultivation of this species. The toxicities that result from deteriorating water quality, such as that from ammonia stress, have lethal effects on juvenile shrimp and can increase their susceptibility to pathogens. The toxicity of ammonia plays an important role in the frequently high mortality during the early stage on shrimp farms. However, little information is available regarding the genetic parameters of the ammonia tolerance of juveniles in the early stage, but this information is necessary to understand the potential for the genetic improvement of this trait. Considering the euryhalinity of L. vannamei and the fact that low salinity can increase the toxicity of ammonia stress, we estimated the heritability of ammonia tolerance in juveniles in 30‰ (normal) and 5‰ (low) salinity in this study using the survival time (ST) at individual level and the survival status at the half-lethal time (SS50) at the family level. In the normal and low salinity conditions and for the merged data, the heritability estimates of the ST (0.784±0.070, 0.575±0.068, and 0.517±0.058, respectively) and SS50 (0.402±0.061, 0.216±0.050, and 0.264±0.050, respectively) were all significantly greater than zero, which indicates that the ammonia-tolerance of shrimp can be greatly improved. So it might provide an alternative method to reduce mortality, help to enhance resistance to pathogens and reduce the occurrence of infectious diseases. The significant positive genetic correlation between ST and body length suggested that ammonia is more toxic to shrimp in the early stage. The medium-strength genetic correlations of the ST and SS50 between the two environments (0.394±0.097 and 0.377±0.098, respectively) indicate a strong genotype-by-environment (G×E) interaction for ammonia tolerance between the different salinity levels. Therefore, salinity-specific breeding programs for ammonia tolerance in shrimp should be purposefully implemented.
关于凡纳滨对虾的实际养殖，集约化养殖系统导致的水质恶化和环境污染是该物种养殖中常见但棘手的问题。水质恶化产生的毒性，如氨应激产生的毒性，对幼虾具有致死作用，并会增加它们对病原体的易感性。氨的毒性在虾养殖场早期频繁出现的高死亡率中起着重要作用。然而，关于早期幼虾氨耐受性的遗传参数信息很少，但这些信息对于了解该性状的遗传改良潜力是必要的。考虑到凡纳滨对虾的广盐性以及低盐度会增加氨应激的毒性这一事实，我们在本研究中使用个体水平的存活时间（ST）和家系水平的半数致死时间存活状态（SS50），估计了幼虾在30‰（正常）和5‰（低）盐度下氨耐受性的遗传力。在正常和低盐度条件下以及合并数据时，ST（分别为0.784±0.070、0.575±0.068和0.517±0.058）和SS50（分别为0.402±0.061、0.216±0.050和0.264±0.050）的遗传力估计值均显著大于零，这表明虾的氨耐受性可以得到极大提高。因此，这可能提供一种降低死亡率的替代方法，有助于增强对病原体的抵抗力并减少传染病的发生。ST与体长之间显著的正遗传相关性表明，氨在早期对虾的毒性更大。两种环境下ST和SS50的中等强度遗传相关性（分别为0.394±0.097和0.377±0.098）表明，不同盐度水平之间氨耐受性存在强烈的基因型×环境（G×E）互作。因此，应针对性地实施针对虾氨耐受性的特定盐度育种计划。
