Boon Nele A M, Fannes Wouter, Rombouts Sara, Polman Katja, Volckaert Filip A M, Huyse Tine
Laboratory of Biodiversity and Evolutionary Genomics, Biology,University of Leuven,Ch. Deberiotstraat 32, B-3000 Leuven,Belgium.
Department of Biology,Royal Museum for Central Africa,Leuvensesteenweg 13, B-3080 Tervuren,Belgium.
Parasitology. 2017 Jun;144(7):954-964. doi: 10.1017/S0031182017000087. Epub 2017 Feb 20.
Hybrid parasites may have an increased transmission potential and higher virulence compared to their parental species. Consequently, hybrid detection is critical for disease control. Previous crossing experiments showed that hybrid schistosome eggs have distinct morphotypes. We therefore compared the performance of egg morphology with molecular markers with regard to detecting hybridization in schistosomes. We studied the morphology of 303 terminal-spined eggs, originating from 19 individuals inhabiting a hybrid zone with natural crosses between the human parasite Schistosoma haematobium and the livestock parasite Schistosoma bovis in Senegal. The egg sizes showed a high variability and ranged between 92·4 and 176·4 µm in length and between 35·7 and 93·0 µm in width. No distinct morphotypes were found and all eggs resembled, to varying extent, the typical S. haematobium egg type. However, molecular analyses on the same eggs clearly showed the presence of two distinct partial mitochondrial cox1 profiles, namely S. bovis and S. haematobium, and only a single nuclear ITS rDNA profile (S. haematobium). Therefore, in these particular crosses, egg morphology appears not a good indicator of hybrid ancestry. We conclude by discussing strengths and limitations of molecular methods to detect hybrids in the context of high-throughput screening of field samples.
与亲本物种相比，杂交寄生虫可能具有更高的传播潜力和更强的毒力。因此，杂交检测对于疾病控制至关重要。先前的杂交实验表明，杂交血吸虫卵具有独特的形态类型。因此，我们比较了虫卵形态学和分子标记物在检测血吸虫杂交方面的性能。我们研究了303个端刺虫卵的形态，这些虫卵来自塞内加尔一个杂交区的19个个体，该杂交区存在人类寄生虫埃及血吸虫和家畜寄生虫牛血吸虫之间的自然杂交。虫卵大小差异很大，长度在92.4至176.4微米之间，宽度在35.7至93.0微米之间。未发现明显的形态类型，所有虫卵在不同程度上都类似于典型的埃及血吸虫卵类型。然而，对同一批虫卵的分子分析清楚地表明存在两种不同的线粒体细胞色素氧化酶亚基1（cox1）部分图谱，即牛血吸虫和埃及血吸虫，而只有单一的核糖体DNA内转录间隔区（ITS rDNA）图谱（埃及血吸虫）。因此，在这些特定的杂交中，虫卵形态似乎不是杂交血统的良好指标。我们通过讨论在高通量筛选野外样本的背景下检测杂交种的分子方法的优点和局限性来得出结论。
