凡纳滨对虾感染虾肝肠胞虫的群体及组织间差异性分析

Differences between populations and tissues of Litopenaeus vannamei infected with Enterocytozoon hepatopenaei

中文关键词: 凡纳滨对虾  虾肝肠胞虫  生长参数  原位杂交

英文关键词: Litopenaeus vannamei  Enterocytozoon hepatopenaei  Growth parameters  in-situ hybridization

中文摘要:

      对来自河北黄骅(HH)、山东平度(PD)、江苏吴江(WJ)和山东日照(RZ)的4个凡纳滨对虾(Litopenaeus vannamei)群体进行了对虾生长参数测量，用TaqMan qPCR检测了凡纳滨对虾各群体的肝胰腺组织中和RZ群体多种组织中的虾肝肠胞虫数量(Amount of Enterocytozoon hepatopenaei, EHP)。结果显示，在主要生长相关参数中，RZ群体最优，该群体EHP载量也最低。不同群体的样本数EHP对数直方图的模式存在差异，HH和PD群体的EHP对数呈双峰分布，而WJ和RZ群体的EHP对数呈单峰分布，代表EHP在不同群体中可能存在不同的传播模式。EHP对数呈单峰分布的群体或从多峰分布的群体中分离出的高EHP对数子群体的对虾体长或体重与EHP对数呈显著的负相关。RZ群体中，各个体不同组织中EHP从高到低的顺序依次是肝胰腺>中肠>血淋巴>鳃>肌肉。肝胰腺、中肠和鳃3个组织中EHP对数相互间的相关性为99.9%的极显著水平(P<0.001)；除了中肠与血淋巴和肝胰腺与血淋巴以外，其余组织间EHP对数的相关性也达到极显著(P<0.01)或显著(P<0.05)水平。用DIG标记的EHP探针对肝胰腺、肌肉、鳃、肠道组织的原位杂交显示，肝胰腺是主要的EHP感染组织，其他组织中杂交信号较弱，但各组织中有少数细胞的EHP易感。

英文摘要:

      Growth-related parameters of individuals from four populations of Litopenaeus vannamei from Huanghua of Heibei Province (HH), Pingdu of Shandong Province (PD), Wujiang of Jiangsu Province (WJ), and Rizhao of Shandong Province (RZ) were assessed. Amount of Enterocytozoon hepatopenaei (EHP) in the hepatopancreas of individuals from all populations and EHP in multiple tissues of shrimp from the RZ population were assessed with TaqMan-based quantitative PCR. The results showed that the RZ population possessed optimal growth-related parameters and the lowest EHP among the four populations. The histograms of case-logarithmic EHPs of the four populations presented different modes. The case distribution of logarithmic EHPs from the HH and PD populations showed double peaks, while those of the WJ and RZ populations showed a single peak. The different distribution modes may indicate a different EHP spread in the four populations. The population with a single peak mode or the higher logarithmic EHP subpopulation isolated from the population with a multiple peak mode showed a significant negative correlation with shrimp body length or body weight to logarithmic EHP. The EHP detected in different tissues of the RZ population followed the order (from highest to lowest), EHP in hepatopancreas > EHP in midgut > EHP in hemolymph > EHP in gills > EHP in muscle. The logarithmic EHP in the hepatopancreas–midgut, hepatopancreas–gills, and midgut–gills had a significant correlation level above 99.9% (P<0.001), while the logarithmic EHP of the other two tissues had a significant correlation level above 99.0% (P<0.01) or above 99.5% (P<0.05), except for midgut–hemolymph and hepatopancreas–hemolymph. In-situ hybridization of a DIG-labeled EHP probe in the hepatopancreas, muscle, gills, and midgut showed that the hepatopancreas is the major target tissue of EHP infection in shrimp. Minor and weak hybridization signals were also observed in other tissues, which indicated that a few cells in those tissues were also susceptible to EHP infection in L. vannamei.