Cellular identity of a novel small subunit rDNA sequence clade of apicomplexans:: Description of the marine parasite Rhytidocystis polygordiae n. Sp (Host: Polygordius sp., polychaeta)
Cellular identity of a novel small subunit rDNA sequence clade of apicomplexans:: Description of the marine parasite Rhytidocystis polygordiae n. Sp (Host: Polygordius sp., polychaeta)
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DOI：
10.1111/j.1550-7408.2006.00109.x
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发表时间：
2006-07-01
影响因子：
2.2
通讯作者：
Ramey, Patricia A.
中科院分区：
文献类型：
--
作者：
Leander, Brian S.;Ramey, Patricia A.
利用电子显微镜和小亚基 (SSU) rDNA 序列的系统发育分析，对大西洋北美水域的一种新种 Rhytidocystis (Apicomplexa) 进行了鉴定。多角纹囊藻 n. sp。是多毛纲 Polygordius sp. 的寄生虫。并成为该属中第四个描述的物种。 R.polygordiae的滋养体是相对较小的长方形细胞(L＝35-55μm；W＝20-25μm)并且其独特之处在于在细胞的两端具有亚末端凹痕。滋养体表面有六至八个纵向的小横向褶皱和数个呈短线状排列的微孔。 R. polygordiae 的滋养体位于肠上皮刷状缘下方，但似乎位于细胞外基质内的上皮细胞之间，而不是细胞内。滋养体具有均匀分布的副糖原颗粒、推定的顶质体、具有管状嵴的线粒体和位于中央的细胞核。滋养体是非运动性的并且缺乏μcron和顶端复合体。 R. polygordiae 的细胞内子孢子具有圆锥形、一些棒状体、微线体、致密颗粒和位于后部的核。从 SSU rDNA 序列推断的系统发育表明，R. polygordiae 与从大砗磲血淋巴中报道的鲜为人知的寄生虫之间存在密切关系。皱孢子虫分支在顶端复合体辐射早期就分化出来，并且与由隐孢子虫寄生虫、单囊虫和新格雷加林组成的分支表现出较弱的亲和力。
A new species of Rhytidocystis (Apicomplexa) is characterized from North American waters of the Atlantic Ocean using electron microscopy and phylogenetic analyses of small subunit (SSU) rDNA sequences. Rhytidocystis polygordiae n. sp. is a parasite of the polychaete Polygordius sp. and becomes the fourth described species within this genus. The trophozoites of R. polygordiae were relatively small oblong cells (L=35-55 mu m; W=20-25 mu m) and distinctive in possessing subterminal indentations at both ends of the cell. The surface of the trophozoites had six to eight longitudinal series of small transverse folds and several micropores arranged in short linear rows. The trophozoites of R. polygordiae were positioned beneath the brush border of the intestinal epithelium but appeared to reside between the epithelial cells within the extracellular matrix rather than within the cells. The trophozoites possessed a uniform distribution of paraglycogen granules, putative apicoplasts, mitochondria with tubular cristae, and a centrally positioned nucleus. The trophozoites were non-motile and lacked a mucron and an apical complex. Intracellular sporozoites of R. polygordiae had a conoid, a few rhoptries, micronemes, dense granules, and a posteriorly positioned nucleus. Phylogenies inferred from SSU rDNA sequences demonstrated a close relationship between R. polygordiae and the poorly known parasite reported from the hemolymph of the giant clam Tridacna crocea. The rhytidocystid clade diverged early in the apicomplexan radiation and showed a weak affinity to a clade consisting of cryptosporidian parasites, monocystids, and neogregarines.