Dall D J
J Theor Biol. 1983 Dec 21;105(4):647-59. doi: 10.1016/0022-5193(83)90225-4.
A theory is presented which can explain the interaction of the major factors known to influence in vitro extrusion of the microsporidian polar filament. It is proposed that the pH, and concentration and species of cation in the external medium influence the activity of carboxylic ionophore molecules in spore membranes in the following manner: (1) Alkaline environmental conditions establish a proton gradient across the spore plasma membrane, and facilitate the activation of ionophore molecules in this membrane. (2) This proton gradient drives an ionophorically-mediated cation/proton exchange across the plasma membrane. (3) As protons are lost from the sporoplasm its alkalinity increases, so that ionophore molecules in organelle membranes (i.e. in the polaroplast and posterior vacuole) are activated. This initiates a cation/proton exchange between sporoplasm and organelles. (4) Continued movement of cations into organelles in the spore causes major osmotic imbalance across spore membranes. This leads to a rapid inflow of water into the spore and swelling of the polaroplast and posterior vacuole. The associated pressure increase in the spore causes the explosive discharge of the polar filament through the polar cap. This model is used to explain previously published results from the literature, and methods of testing predictions generated by this hypothesis are outlined.
本文提出了一种理论，该理论能够解释已知影响微孢子虫极丝体外挤出的主要因素之间的相互作用。我们认为，外部介质中的pH值、阳离子浓度和种类以如下方式影响孢子膜中羧酸离子载体分子的活性：（1）碱性环境条件在孢子质膜上建立质子梯度，并促进该膜中离子载体分子的活化。（2）这种质子梯度驱动质膜上由离子载体介导的阳离子/质子交换。（3）随着质子从孢子质中流失，其碱度增加，从而细胞器膜（即极质体和后液泡）中的离子载体分子被激活。这引发了孢子质与细胞器之间的阳离子/质子交换。（4）阳离子持续进入孢子中的细胞器会导致孢子膜两侧出现严重的渗透失衡。这会导致水迅速流入孢子，极质体和后液泡肿胀。孢子内相关的压力增加导致极丝通过极帽爆炸性射出。该模型用于解释文献中先前发表的结果，并概述了检验该假设所产生预测的方法。
