Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science, P.O. Box 8146 Dep., 0033, Oslo, Norway,
Parasitol Res. 2014 Apr;113(4):1591-604. doi: 10.1007/s00436-014-3806-z. Epub 2014 Feb 18.
Individual sarcocysts were isolated from fresh or alcohol-fixed muscle samples of two moose from Alberta, Canada, and examined by light (LM) and scanning electron microscopy (SEM) and molecular methods, comprising polymerase chain reaction (PCR) amplification and sequencing of the complete18S rRNA gene and the partial cytochrome c oxidase subunit I gene (cox1). By LM, four sarcocyst types were recognized, and the sequencing results showed that each type represented a distinct species, i.e. Sarcocystis alces, Sarcocystis alceslatrans, Sarcocystis ovalis and Sarcocystis taeniata n. sp. The finding of S. alceslatrans and S. ovalis has been reported briefly previously, but further details are provided here, including the ultrastructure of sarcoysts of S. alceslatrans as seen by SEM. The species S. alces was found for the first time in Canadian moose, whereas the finding of S. taeniata is the first record of this species in any host. The sarcocysts of S. taeniata were sac-like and about 1,000-1,100 × 60-80 μm in size. By LM, the cysts had a thin and smooth wall with no visible protrusions, whereas SEM revealed that the cyst surface had sparsely but regularly distributed, thin ribbon-like protrusions, about 2 μm long and 0.2 μm wide, lying flat against the surface and leaving most of the cyst surface naked. Similar protrusions have previously been reported from Sarcocystis grueneri in reindeer, which was found by sequence comparisons and phylogenetic analyses to be the species most closely related to S. taeniata. The phylogenetic analyses further suggested that S. taeniata, like S. alces and S. alceslatrans, use canids as definitive hosts, whereas corvid birds are known definitive hosts for S. ovalis. In contrast to the three other species found, S. taeniata displayed considerable intra-specific and intra-isolate sequence variation (substitutions, insertions/deletions) in certain regions of the 18S rRNA gene.
从加拿大艾伯塔省的两头麋鹿的新鲜或酒精固定的肌肉样本中分离出个体肉孢子虫，通过光学显微镜（LM）和扫描电子显微镜（SEM）以及分子方法进行检查，包括聚合酶链反应（PCR）扩增和完整 18S rRNA 基因和部分细胞色素 c 氧化酶亚基 I 基因（cox1）的测序。通过 LM，识别出四种肉孢子虫类型，测序结果表明每种类型代表一个独特的物种，即鹿肉孢子虫、鹿肉孢子虫、卵形肉孢子虫和 Taeniata 肉孢子虫。此前曾简要报道过 S. alceslatrans 和 S. ovalis 的发现，但这里提供了更详细的信息，包括 SEM 观察到的 S. alceslatrans 肉孢子虫的超微结构。在加拿大麋鹿中首次发现 S. alces 种，而 Taeniata 种的发现是该物种在任何宿主中的首次记录。Taeniata 肉孢子虫的肉孢子呈囊状，大小约为 1000-1100×60-80μm。通过 LM，囊肿具有薄而光滑的壁，没有可见的突起，而 SEM 显示囊肿表面稀疏但规则地分布着薄的带状突起，长约 2μm，宽 0.2μm，平贴在表面上，使囊肿表面大部分裸露。以前在驯鹿中的 Greneri 肉孢子虫中也报道过类似的突起，通过序列比较和系统发育分析发现，该种与 Taeniata 种最为密切相关。系统发育分析进一步表明，Taeniata 种与 S. alces 和 S. alceslatrans 一样，使用犬科动物作为终末宿主，而雀形目鸟类是卵形肉孢子虫的已知终末宿主。与其他三种发现的物种不同，Taeniata 种在 18S rRNA 基因的某些区域显示出相当大的种内和种内序列变异（取代、插入/缺失）。
