Department of Biological and Ecological Sciences, Tuscia University, Viale dell'Università snc, 01100 Viterbo, Italy; Department of Public Health and Infectious Diseases, Section of Parasitology, Sapienza University of Rome, Laboratory affiliated to "Istituto Pasteur Italy - Fondazione Cenci-Bolognetti", P.le Aldo Moro 5, 00185 Rome, Italy.
Department of Public Health and Infectious Diseases, Section of Parasitology, Sapienza University of Rome, Laboratory affiliated to "Istituto Pasteur Italy - Fondazione Cenci-Bolognetti", P.le Aldo Moro 5, 00185 Rome, Italy; Department of Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, Villa Comunale 1, 80121 Naples, Italy.
Infect Genet Evol. 2021 Aug;92:104887. doi: 10.1016/j.meegid.2021.104887. Epub 2021 Apr 30.
The southern Pacific Ocean, off the New Zealand coast, has been reported as one sympatric area of the two parasite species Anisakis pegreffii and A. berlandi. Here, a multilocus genotyping approach, based on a panel of eleven DNA microsatellite (SSR) loci plus the sequences analysis of the nuclear nas10 nDNA and the mitochondrial mtDNA cox2 gene loci, was applied to a total of N = 344 adults and larvae of Anisakis spp. from cetacean and fish species, respectively. Out of the newly scored SSR loci, Anisl 15 and Anisl 2 showed fixed alternative alleles between A. pegreffii and A. berlandi resulting as 100% diagnostic loci. Out of SSRs Anisl 00314 and Anisl 7 previously disclosed, two additional loci, i.e., Anisl 4 and Anisl 22, were found to be sex-linked. The Bayesian genotypes clustering approach (STRUCTURE) allowed identification, with a 100% of probability value, N = 208 specimens to the "pure parental" A. pegreffii, N = 133 to the "pure parental" A. berlandi, while one adult and two larval stages showed mixed ancestry between the two groups having, in all cases, a Q-value = 0.50. NEWHYBRIDS analysis assigned (100% of probability) those specimens to their F1 hybrid category. This represents the first evidence of contemporary hybridization between the two parasite species in a sympatric area. The pairwise F values estimated at intraspecific and interspecific level, inferred from both SSR loci and mitochondrial mtDNA cox2 sequences, have also demonstrated the existence of two distinct panmictic units in this study area, corresponding respectively to A. pegreffii and A. berlandi. The results obtained support the useful application of a multilocus approach in the identification of sibling species and their hybrid categories in sympatric areas. The possible use of sex-linked SSR loci of the two species of the A. simplex (s. l.), for sex determination of their larval stages, is also suggested.
据报道，南太平洋新西兰沿海是两种寄生虫物种——棘头虫属的阿尼西克氏棘头虫（Anisakis pegreffii）和阿尼西克氏贝兰德虫（A. berlandi）的共生区之一。在这里，应用了一种基于十一个 DNA 微卫星（SSR）基因座的多位点基因分型方法，外加核 nas10 nDNA 和线粒体 mtDNA cox2 基因座的序列分析，对总共 344 个来自鲸目动物和鱼类的成年和幼虫的棘头虫属进行了分析。在新评分的 SSR 基因座中，Anisl 15 和 Anisl 2 在阿尼西克氏棘头虫和阿尼西克氏贝兰德虫之间显示出固定的替代等位基因，成为 100%的诊断基因座。在之前披露的 SSRs Anisl 00314 和 Anisl 7 之外，还发现了另外两个基因座，即 Anisl 4 和 Anisl 22，是性连锁的。贝叶斯基因型聚类方法（STRUCTURE）允许以 100%的概率值识别 N=208 个标本为“纯亲代”的阿尼西克氏棘头虫，N=133 个标本为“纯亲代”的阿尼西克氏贝兰德虫，而一个成年和两个幼虫阶段在两组之间显示出混合遗传，在所有情况下，Q 值=0.50。NEWHYBRIDS 分析将这些标本（100%的概率）分配到它们的 F1 杂交类别。这是在共生区首次发现这两种寄生虫物种之间的当代杂交。从 SSR 基因座和线粒体 mtDNA cox2 序列推断的种内和种间的成对 F 值也表明，在本研究区存在两个不同的混合单元，分别对应于阿尼西克氏棘头虫和阿尼西克氏贝兰德虫。研究结果支持在共生区识别姐妹种及其杂交类别的多基因座方法的有用应用。还建议使用这两种阿尼西克氏（s. l.）物种的性连锁 SSR 基因座来确定其幼虫阶段的性别。
