Ultrastructure of rhoptry development in Plasmodium falciparum erythrocytic schizonts
Ultrastructure of rhoptry development in Plasmodium falciparum erythrocytic schizonts
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DOI：
10.1017/s0031182099006320
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发表时间：
2000-09-01
期刊：
影响因子：
2.4
通讯作者：
Mitchell, GH
中科院分区：
文献类型：
--
作者：
Bannister, LH;Hopkins, JM;Mitchell, GH
在从恶性疟原虫裂殖体中分离出裂殖子之前，在每个裂殖子芽中合成和组装各种特定阶段的细胞器。裂殖子的顶端靠近内有丝分裂纺锤体的末端启动。在每一个部位，核膜形成包被的小泡，出现单个盘状或杯状高尔基体池。连续切片的重建表明，这种结构从核膜接收小泡，然后释放包被的小泡，产生顶端分泌细胞器。棒状幼虫首先形成球状结构，并通过边缘小泡的逐渐融合而生长。随着每个棒状体的发育，其内有两个不同的区域，一个是顶端网状区，电子透光区由颗粒状物质线条隔开，另一个是更均匀的颗粒状基底区。顶端部分延伸到导管内，有证据表明在导管顶端有进一步的囊泡融合。圆形的锥体底部逐渐变得更加致密，形成一个球状的质量块，并且在管道中也发生了压实。通常情况下，一个棒状体会比另一个更早成熟。冰冻裂管膜在内外向骨折面膜内颗粒的大小和数量不对称。
Prior to the separation of merozoites from the Plasmodium falciparum schizont, various stage-specific organelles are synthesized and assembled within each merozoite bud. The apical ends of the merozoites are initiated close to the ends of endomitotic spindles. At each of these sites, the nuclear membrane forms coated vesicles, and a single discoidal or cuplike Golgi cisterna appears. Reconstruction from serial sections indicates that this structure receives vesicles from the nuclear envelope and in turn gives off coated vesicles to generate the apical secretory organelles. Rhoptries first form as spheroidal structures and grow by progressive fusion of small vesicles around their margins. As each rhoptry develops, 2 distinctive regions separate within it, an apical reticular zone with electron-lucent areas separated by cords of granular material, and a more homogenously granular basal region. The apical part elongates into the duct, with evidence for further vesicular fusion at the duct apex. The rounded rhoptry base becomes progressively more densely packed to form a spheroidal mass, and compaction also occurs in the duct. Typically, one rhoptry matures before the other. Cryofractured rhoptry membranes show asymmetry in the sizes and numbers of intramembranous particles at the internally- and externally-directed fracture faces.