Zoospores of the Oyster Pathogen, Dermocystidium marinum. I. Fine Structure of the Conoid and Other Sporozoan-Like Organelles
Zoospores of the Oyster Pathogen, Dermocystidium marinum. I. Fine Structure of the Conoid and Other Sporozoan-Like Organelles
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牡蛎病原体 Dermocystidium marinum 的游动孢子。
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发表时间：
1976
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通讯作者：
F. Perkins
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作者：
F. Perkins
描述了一种与孢子虫中发现的顶端复合体，该复合体来自Marlnum Dermocystidium Marlnum Mackin，Owen和Collier的游动孢子，Collier是美国牡蛎(Crassostrea Oirgiica Gmelin)的病原体。该复合体由一个圆锥体、极环、多达39个亚质膜微管、棒状微管和微线组成。此外，还发现了微孔和相当于膜下的膜。在内质网的胞体、包涵体和锥形腔内的小泡中发现酸性磷酸酶活性。用Thiery法未检测到棒状体和微线体中的多糖。观察表明，D.marum是Apicomplexa亚门的一种原生动物，与球虫Sporosasida Leuckart关系最近。由于Gustafson等人的最初描述。(1954)，新的作者注意到球虫、Gregincs、Sarcocystis sp.、Besnoitia sp.和Frenkelia sp.在一个或多个细胞周期中，所有细胞在细胞的前部或末端都有中空的锥形结构。这种细胞器称为圆锥体，由管状亚基组成，前端螺旋状排列成直径0.08μ.m至0.4μ.m的截形中空锥体，后端直径0.2μ.m至0.53μ.m(肖尔蒂塞克，1973年)。圆锥体的前面是2个(可能有3个：Porchet-Hennere，1975)前圆锥体环，由致密的颗粒物质组成，通过致密的物质冠层连接到圆锥体，在最前端有一个开口。一个由电子致密物质组成的环，即极环，环绕着圆锥。该环是两个紧密相对的单位膜(“膜下膜”)的前部精加工，它们略低于质膜。两个或更多由电子致密物质组成的瓶状、薄膜状的囊汇聚在圆锥体上，每个“烧瓶”的颈部都位于圆锥体内。这些细胞器被称为棒状细胞器或成对细胞器，被认为含有裂解酶，有助于机体对宿主细胞的渗透。散布在细胞前1⁄2或11.i的是微线，它们是由电子致密物质组成的索状、膜结合囊。一些工作人员建议1976年1月26日收到Rhop bi和Microronemes。·投稿编号：786，弗吉尼亚州马林科学研究所，格洛斯特角，弗吉尼亚州，23062。959一个功能系统，可能是后者导致了前者(Vivier和Petitprez，1972)。附着在极环上并从极环辐射的微管通常有22到24个微管，它们位于“膜下膜”下面，向细胞后方延伸大部分距离。在大多数具有圆锥体的生物体中，还发现有1至9个内陷的质膜，即微孔。这些特殊的结构通常在内陷的远端周围有一圈电子致密的材料，另一外圆柱状的领子是通过内折“膜下膜”而形成的。后者在凹陷的近端不连续。圆锥体、极环、膜下微管、微线和棒状体统称为心尖复合体(Levine，1973)。在原生动物中观察到的这种复合体的一致性似乎与其他原因有关，导致了Apicomplexa Levine 1970亚门的形成，其中包括梨质体、Gregine和球虫。后者包括弓形虫、肉孢子虫、贝斯氏原虫、疟原虫、弗氏原虫、艾氏原虫和等孢子虫。本文证明，牡蛎病原菌海洋皮囊线虫也具有上述细胞器，因此与尖丛线虫有亲缘关系。关于病原体的亲和力，文献中有许多建议，包括不同的类群，如鼻孢子菌科960寄生虫学杂志，第一卷。62，No.6,1976年12月，内霉菌门(Mackin，1962)，Chytricliales的Sy11chytriaceae(Mackin和BoswolJ，1956)，迷宫菌(Mackin和Ray，1966)，子囊菌(Mackin，1951)，Japlosporida(Spraogue，1954)，和EntomophtJ1oralcs(F.K.Sparrow，Jr.)在雷，1954)。Mackin和Ray(1066)将这种生物重新命名为迷宫霉菌，因此认为它是迷宫霉属的一员。他们的决定源于对滑行细胞的观察，这些细胞带有迷宫壳状“轨迹”、质突和类似于萨瓦迷宫粘虫的营养分裂图形(Dul，ost1 1921)。Perkins(1974)没有在牡蛎病原体中发现任何迷路特征，除了一种不寻常的动体颗粒，并提出了当时Marinum不可能与任何k11自己的群体有关的观点。
An apical complex comparable to that found in the Sporozoa is described from zoospores of Dermocystidium marlnum Mackin, Owen, and Collier, a pathogen of the American oyster (Crassostrea oirginica Gmelin) . The complex consists of a conoid, polar ring, up to 39 subplasmalemmal microtubules, rhoptries, and micronemes. Micropores and a subpellicular membrane equivalent were also found. Acid phosphatase activity was found in cistemae of the endoplasmic reticulum, inclusion bodies, and vesicles within the conoid lumen. No polysaccharides were detected in the rhoptries and micronemes using the Thiery method. Observations indicate that D. marinum is a protozoan in the subphylum Apicomplexa and is most closely related to the coccidian Sporozoasida Leuckart. Since the initial description by Gustafson et al. (1954), nwnerous authors have noted that coccidians, gregarincs, Sarcocystis sp ., Besnoitia sp., and Frenkelia sp. all have, in one or more cell stages iJ1 the li£e cycle, a hollow, cone-like structure at Lhe antedor end of the cell. This organelle, termed a conoid, consists of tubular subunits, spirally arranged to form a truncated hollow cone 0.08 μ.m to 0.4 μ.m in diameter at the anterior end and 0.2 μ.m to 0.53 μ.m at the posterior end ( Scholtyseck, 1973). Anterior to the conoid are 2 (possibly 3: Porchet-Hennere, 1975) preconoidal rings consisting of elecb·on-dense granular material connected to the conoid by a canopy of elecb·on-dense material which has an opening at the extreme anterior end. A ring of electrondense material, the polar ring, encircles the conoid. The ring is an anterior elaboration of the two closely opposed unit membranes (''subpellicular membrane") which lie slightly under the plasmalcmma. Two or more flaskshaped, membrane-bound sacs of electrondense material converge on the conoid, the neck of each "flask" lying within the conoid Ju.men. These sbuctw·es, termed rhoptries or paired organelles, are believed to contain lytic enzymes which aid the organism in host cell penetration. Scattered throughout the anterior 1⁄2 or 11.i of the cell are the micronemes which are cord-like, membrane-bound sacs of electron-dense material. Some workers have suggested the rhopbi es and micronemes are Received for publication 26 January 1976. • Contribution No. 786, Virginia Institute of Maline Science, Gloucester Point, Virg inia 23062. 959 one functional system, possibly the latter giving rise to the former (Vivier and Petitprez, 1972) . Attached to and radiating from the polar ring are generally 22 to 24 microtubules which lie beneath the "subpellicular membrane" and extend most of the distance toward the cell posterior. In most of the organisms with conoids are also found 1 to 9 invaginations of the plasmalemma, the micropores. These specialized stmctures often have a collar of electron-dense mate1ial around the distal part of the invaginatiou and another outer cylindrical collar fonncd by infolding of the "subpellicular membrane." The latter is discontinuous at the proximal end of the invagi.nation. Collectively the conoid, polar ring, subpellicular microtubles, micronemes, and rhoptries have been termed the apical complex (Levine, 1973). The consistency with which the complex has been observed in Protozoa that appear to be related for other reasons, has led to the consb.uction of the subphylum Apicomplexa Levine 1970, which includes the piroplasms, gregarines, and coccidians. The latter group includes sp ecies of Toxoplasma, Sarcocystis, Besnoit ia, Plasmodium, Frenkelia, Eirneria, and Isospora. In this paper it is shown that the oyster pathogen, Dermocystidium marinum, also has the organelles described above and thus has affinities with the Apicomplexa. There are numerous suggestions in the literature as to the affinities of the pathogen, ranging through such diverse groups as the Rhinosporidiaceae 960 THE JOURNAL OF PARASITOLOGY, VOL. 62, NO. 6, DECEMBER 1976 of the Endomycctales (Mackin, 1962), Sy11chytriaceae of the Chytricliales (Mackin and BoswolJ, 1956), Labyrinthulia ( Mackin and Ray, 1966), Ascomycctes (Mackin, 1951), lJaplosporida (Sprague, 1954) , and EntomophtJ1oralcs (F. K. Sparrow, Jr. in Ray, 1954). Mackin and Ray ( 1066) have renamed the organism Labyrinthomyxa marina thus considering it to be allied to the Labyrinthulia. Their decision resulted from observations of gliding cells with labyrinlhulid "tracks," plasmoclia, and vegetative division figures similar to those of Labyrinthomyxa sauvageatii (Dul,osct1 1921). Perkins ( 1974) did not find any laby1inthulid characteristics in the oyster pathogen, except an unusual kinetosome granule, and e»'Presscd the opinion that D. marinu.m could not, at that time, be related to any k11own group