Sepúlveda Fabiola A, González M Teresa
Programa Ciencias Aplicadas, mención Sistemas Marinos Costeros, Universidad de Antofagasta, P.O. Box 170, Antofagasta, 1240000, Chile.
Instituto de Ciencias Naturales "Alexander von Humboldt", Facultad de Ciencias del Mar y Recursos Biológicos, Universidad de Antofagasta, Antofagasta, 1240000, Chile.
Parasit Vectors. 2015 May 22;8:282. doi: 10.1186/s13071-015-0892-4.
The monogenean, Zeuxapta seriolae, is a host-specific parasite that has an extensive geographical distribution on its host, Seriola lalandi, and is considered highly pathogenic in farmed fish. In recent years, developing cultures of S. lalandi in different coastal localities in Southeastern Pacific Ocean (SEP) have been affected by moderate and heavy infections of this parasite, attributed to contagion from wild to farmed fish. Here, we evaluated the pattern of genetic variations and biological traits of Z. seriolae in a spatial and temporal scale across its geographical distribution in SEP to determine its genetic status and biological traits, which could affect its transmission dynamics from wild to farmed fish.
Wild fish and their parasites were sampled from fisheries in the northern Chilean coast (NCC: 24°S-30°S) and Eastern islands (JFA: ca 33°S; 80°W) between 2012 and 2014. Fragments of 816 bp of the cytochrome c oxidase subunit I (COI) gene was sequenced for 112 individuals from NCC and 63 from JFA and compared using AMOVA. Prevalence and intensity of Z. seriolae were calculated for each area. The parasite body size, fecundity and size at sexual maturity were estimated for 177 parasites from NCC and 128 from JFA, and significant differences were evaluated using GLM.
Geographical genetic structuring was detected for Z. seriolae across SEP, with a population in NCC and the other in JFA, both with the same high haplotype diversity. Neutrality tests and mismatch analyses indicated that both Z. seriolae populations are stable. Parasite biological traits such as fecundity, body size, and size at sexual maturity, and population parameters varied significantly between geographical areas.
Two genetic groups of Z. seriolae were detected in wild fish across SEP. Because of the seasonal migration of wild host and temporal contact with farming, quantifying the genetic diversity and level of gene flow or isolation between parasite populations is useful for fish health management in farming. The smallest size of sexual maturity in parasites from NCC is predictive of shorter life cycles, and their high genetic diversity suggests high evolutionary potential and high transmission of this parasite to farmed hosts.
单殖吸虫Zeuxapta seriolae是一种宿主特异性寄生虫，在其宿主黄条鰤（Seriola lalandi）上具有广泛的地理分布，并且被认为对养殖鱼类具有高度致病性。近年来，在东南太平洋（SEP）不同沿海地区开展的黄条鰤养殖受到这种寄生虫的中度和重度感染影响，这归因于野生鱼向养殖鱼的传播。在此，我们在SEP的地理分布范围内，在空间和时间尺度上评估了Zeuxapta seriolae的遗传变异模式和生物学特性，以确定其遗传状况和生物学特性，这可能会影响其从野生鱼到养殖鱼的传播动态。
2012年至2014年期间，从智利北部海岸（NCC：南纬24°-30°）和东部岛屿（JFA：约南纬33°；西经80°）的渔场采集野生鱼类及其寄生虫。对来自NCC的112个个体和来自JFA的63个个体的细胞色素c氧化酶亚基I（COI）基因的816 bp片段进行测序，并使用分子方差分析（AMOVA）进行比较。计算每个区域Zeuxapta seriolae的感染率和感染强度。对来自NCC的177个寄生虫和来自JFA的128个寄生虫估计寄生虫的体长、繁殖力和性成熟时的大小，并使用广义线性模型（GLM）评估显著差异。
在SEP范围内检测到Zeuxapta seriolae的地理遗传结构，一个群体在NCC，另一个在JFA，两者都具有相同的高单倍型多样性。中性检验和错配分析表明，两个Zeuxapta seriolae群体都是稳定的。寄生虫的生物学特性，如繁殖力、体长和性成熟时的大小，以及群体参数在不同地理区域之间存在显著差异。
在SEP的野生鱼类中检测到两个Zeuxapta seriolae遗传群体。由于野生宿主的季节性迁移以及与养殖的时间接触，量化寄生虫群体之间的遗传多样性和基因流动或隔离水平对于养殖中的鱼类健康管理是有用的。来自NCC的寄生虫性成熟时的最小尺寸预示着较短的生命周期，并且它们的高遗传多样性表明这种寄生虫具有高进化潜力和向养殖宿主的高传播性。
