Department of Parasitology and Mycology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Infectious Diseases Research Center, Kermanshah University of Medical Sciences, Kermanshah, Iran.
Ann Parasitol. 2021;67(2):351-352. doi: 10.17420/ap6702.350.
Dear Editor-in-Chief, In Annals of Parasitology 2021, 67(1), 55-65, a paper entitled "Genetic characterization and phylogenetic analysis of Fasciola species based on ITS2 gene sequence, with first molecular evidence of intermediate Fasciola from water buffaloes in Aswan, Egypt" was published with great interest [1]. After reading the article carefully and critically, we think some points should be noted. Fasciola species are meiotically functional diploid, can produce sperm and temporarily and store in the seminal vesicles. This type is named spermic fluke [2]. On the other hand, intermediate Fasciola with morphological characteristics intermediates between F. hepatica and F. gigantica with no sperm or aspermic and no sperm in seminal vesicles. However, this is also seen in older flukes [3-5]. It seems that morphological studies based on spermatogenesis ability were necessary for this study. Also, this parasite's anthelmintic resistance is due to aspects of biology, and population structure depends on genetic diversity [6]. We question whether there are any documents about and sequences of mitochondrial markers as COX (Cytochrome Oxidase) and NAD (Nicotinamide Adenine Dinucleotide) to analyze intraspecific phylogenetic relationship in addition to nuclear gene? In Table 3, the pairwise distances between three groups of Fasciola spp. from different livestock animals were low, ranging from 0.004 to 0.01 with an overall mean of 0.008. Genetic diversity is described as a tendency of genetic characteristics to vary and serves as a way for the population to adapt to changing hosts and environments [7]. The nature of the nuclear gene (ITS) is instability. It is better to use mitochondrial sequence data to compare diversity. Also, genetic discrimination grade from infra population to meta population is annotated by Fst value ranging; 0 to 1. Fst values between 0-0.05 indicated a low genetic differentiation population [8]. It seems that by calculating Fst and showing the gene migration based on mitochondrial sequences data of specimens, this study's species population will be obtained. Also, Tajima's D and Fu's F in all loci populations based on GenBank data may show the Fasciola haplotypes' population proximity. Here we recommend, that Omar et al. [1] studies that molecular phylogeny with mitochondrial DNA efectively used for appropriate diferentiation of haplotypes and spermatogenic ability by carmen allium staining helps them find the physiological aspects. Of course, more prominent populations are needed to find intermediate types. [1] Omar M.A, Elmajdoub L.O., Ali A.O., Ibrahim D.A., Sorour S.S., Al-Wabel M.A., Suresh M., Metwally A.M. 2021. Genetic characterization and phylogenetic analysis of Fasciola species based on ITS2 gene sequence, with first molecular evidence of intermediate Fasciola from water buffaloes in Aswan, Egypt. Annals of Parasitology 67: 55-65. doi:10.17420/ap6701.312 [2] Sanderson A. 1953. Maturation and probable gynogenesis in the liver fluke, Fasciola hepatica L. Nature 172: 110-112. doi:10.1038/172110a0 [3] Hayashi K., Ichikawa-Seki M., Mohanta U.K., Singh T.S., Shoriki T., Sugiyama H., Itagaki T. 2015. Molecular phylogenetic analysis of Fasciola flukes from eastern India. Parasitology International 64: 334-338. https://doi.org/10.1016/j.parint.2015.04.004 [4] Ichikawa-Seki M., Tokashiki M., Opara M.N., Iroh G., Hayashi K., Kumar U.M., Itagaki T. 2017. Molecular characterization and phylogenetic analysis of Fasciola gigantica from Nigeria. Parasitology International 66: 893-897. doi:10.1016/j.parint.2016.10.010 [5] Rouhani S., Raeghi S., Mirahmadi H., Fasihi Harandi M., Haghighi A., Spotin A. 2017. Identification of Fasciola spp. in the east of Iran, based on the spermatogenesis and nuclear ribosomal DNA (ITS1) and mitochondrial (ND1) genes. Archives of Clinical Infectious Diseases 12:e57283. doi:10.5812/archcid.57283 [6] Hodgkinson J., Cwiklinski K., Beesley N., Paterson S., Williams D., Devaney E. 2013. Identification of putative markers of triclabendazole resistance by a genome-wide analysis of genetically recombinant Fasciola hepatica. Parasitology 140: 1523. doi:10.1017/S0031182013000528 [7] Bozorgomid A., Rouhani S., Harandi M.F., Ichikawa- Seki M., Raeghi S. 2020. Genetic diversity and distribution of Fasciola hepatica haplotypes in Iran: molecular and phylogenetic studies. Veterinary Parasitology: Regional Studies and Reports 19: 00359. [8] Rouhani S., Raeghi S., Spotin A. 2017. Spermatogenic and phylo-molecular characterizations of isolated Fasciola spp. from cattle, North West Iran. Pakistan Journal of Biological Sciences 20: 204-209.
在 2021 年的《寄生虫学年鉴》第 67（1）卷，55-65 页上发表了一篇题为“基于 ITS2 基因序列的 Fasciola 种的遗传特征和系统发育分析，首次从埃及阿斯旺的水牛中获得中间 Fasciola 的分子证据”的论文[1]。在仔细批判性地阅读这篇文章后，我们认为有几点需要注意。Fasciola 物种是减数分裂功能的二倍体，可以产生精子并暂时储存在精囊内。这种类型被称为精子虫[2]。另一方面，中间 Fasciola 的形态特征介于肝片形吸虫和巨片形吸虫之间，没有精子或无精，精囊内也没有精子。然而，这种情况也见于较老的吸虫[3-5]。似乎有必要进行基于精子发生能力的形态学研究。此外，这种寄生虫的抗药性是由于生物学方面的原因，种群结构取决于遗传多样性[6]。我们质疑除了核基因外，是否有关于线粒体标记物（如 COX（细胞色素氧化酶）和 NAD（烟酰胺腺嘌呤二核苷酸））的文献和序列，用于分析种内系统发育关系？在表 3 中，来自不同家畜的 Fasciola spp. 三组之间的成对距离较低，范围为 0.004 至 0.01，平均为 0.008。遗传多样性被描述为遗传特征变化的趋势，是种群适应不断变化的宿主和环境的一种方式[7]。核基因（ITS）的性质不稳定。最好使用线粒体序列数据来比较多样性。此外，从亚种群到元种群的遗传歧视等级通过 Fst 值注释，范围为 0-1。Fst 值在 0-0.05 之间表示种群遗传分化程度较低[8]。似乎通过计算 Fst 值并根据标本的线粒体序列数据显示基因迁移，可以获得该研究的物种种群。此外，基于 GenBank 数据的所有基因座群体中的 Tajima's D 和 Fu's F 可能表明 Fasciola 单倍型的种群亲缘关系。在这里，我们建议 Omar 等人[1]的研究通过卡门氏染色法进行的分子系统发育与线粒体 DNA 有效结合，有助于他们发现生理方面。当然，需要更多突出的种群来发现中间类型。
[1] Omar M.A, Elmajdoub L.O., Ali A.O., Ibrahim D.A., Sorour S.S., Al-Wabel M.A., Suresh M., Metwally A.M. 2021. Genetic characterization and phylogenetic analysis of Fasciola species based on ITS2 gene sequence, with first molecular evidence of intermediate Fasciola from water buffaloes in Aswan, Egypt. Annals of Parasitology 67: 55-65. doi:10.17420/ap6701.312
[2] Sanderson A. 1953. Maturation and probable gynogenesis in the liver fluke, Fasciola hepatica L. Nature 172: 110-112. doi:10.1038/172110a0
[3] Hayashi K., Ichikawa-Seki M., Mohanta U.K., Singh T.S., Shoriki T., Sugiyama H., Itagaki T. 2015. Molecular phylogenetic analysis of Fasciola flukes from eastern India. Parasitology International 64: 334-338. https://doi.org/10.1016/j.parint.2015.04.004
[4] Ichikawa-Seki M., Tokashiki M., Opara M.N., Iroh G., Hayashi K., Kumar U.M., Itagaki T. 2017. Molecular characterization and phylogenetic analysis of Fasciola gigantica from Nigeria. Parasitology International 66: 893-897. doi:10.1016/j.parint.2016.10.010
[5] Rouhani S., Raeghi S., Mirahmadi H., Fasihi Harandi M., Haghighi A., Spotin A. 2017. Identification of Fasciola spp. in the east of Iran, based on the spermatogenesis and nuclear ribosomal DNA (ITS1) and mitochondrial (ND1) genes. Archives of Clinical Infectious Diseases 12:e57283. doi:10.5812/archcid.57283
[6] Hodgkinson J., Cwiklinski K., Beesley N., Paterson S., Williams D., Devaney E. 2013. Identification of putative markers of triclabendazole resistance by a genome-wide analysis of genetically recombinant Fasciola hepatica. Parasitology 140: 1523. doi:10.1017/S0031182013000528
[7] Bozorgomid A., Rouhani S., Harandi M.F., Ichikawa- Seki M., Raeghi S. 2020. Genetic diversity and distribution of Fasciola hepatica haplotypes in Iran: molecular and phylogenetic studies. Veterinary Parasitology: Regional Studies and Reports 19: 00359.
[8] Rouhani S., Raeghi S., Spotin A. 2017. Spermatogenic and phylo-molecular characterizations of isolated Fasciola spp. from cattle, North West Iran. Pakistan Journal of Biological Sciences 20: 204-209.
