Beakes GW, Glockling SL
Department of Biological and Nutritional Sciences, University of Newcastle upon Tyne, Newcastle upon Tyne, NE1 7RU, United Kingdom.
Fungal Genet Biol. 1998 Jun;24(1-2):45-68. doi: 10.1006/fgbi.1998.1072.
The gun cells which develop from germinating cysts in Haptoglossa produce a specialized infection apparatus, the injection tube. Upon eversion this tube fires a missile-like projectile which penetrates the host cuticle and then forms an infective sporidium within the body cavity of the nematode host. The temporal assembly of this complex cell organelle has been determined by serial-section reconstructions of maturing gun cells in a previously undescribed Haptoglossa species. The differentiation of the partially walled inverted injection tube is an unusual example of internal tube growth, in which membrane and wall assembly are temporally separated. There is no evidence that the shape of this inverted tube, which coils around the nucleus until it doubles back on itself, is dictated by the disposition of cytoplasmic microtubules. However, actin-like material was associated with the delimiting membrane of the differentiating tube, particularly in the regions of extension. From these studies it seems likely that the "head and buttress" structures previously depicted as the barbed tip of the "harpoon-like" penetration missile are part of a separate, structurally complex system which we suggest locks the "missile" into position in the invaginated injection tube. From this detailed account of cell architecture, models for the likely mechanism of infection cell firing are discussed, and unresolved questions relating to the cell biology and biochemistry of these complex organelles are highlighted. Copyright 1998 Academic Press.
在触舌菌属中，由萌发的囊肿发育而来的枪细胞会产生一种特殊的感染器官——注射管。外翻时，该管会发射出类似导弹的投射物，穿透宿主表皮，然后在线虫宿主的体腔内形成感染性孢子体。通过对一种此前未描述过的触舌菌属物种中成熟枪细胞的连续切片重建，确定了这种复杂细胞器的时间组装过程。部分有壁的倒置注射管的分化是内管生长的一个不寻常例子，其中膜和壁的组装在时间上是分开的。没有证据表明这种倒置管的形状（它围绕细胞核盘绕，直到自身折返）是由细胞质微管的排列决定的。然而，肌动蛋白样物质与分化管的界定膜相关，特别是在延伸区域。从这些研究来看，之前被描绘为“鱼叉状”穿透导弹带刺尖端的“头部和支撑”结构似乎是一个独立的、结构复杂的系统的一部分，我们认为这个系统将“导弹”锁定在内陷注射管中的位置。基于对细胞结构的详细描述，讨论了感染细胞发射可能机制的模型，并突出了与这些复杂细胞器的细胞生物学和生物化学相关的未解决问题。版权所有1998年学术出版社。
