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首页> 外文期刊>Protoplasma: An International Journal of Cell Biology >When is a cell not a cell? A theory relating coenocytic structure to the unusual electrophysiology of Ventricaria ventricosa (Valonia ventricosa)
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When is a cell not a cell? A theory relating coenocytic structure to the unusual electrophysiology of Ventricaria ventricosa (Valonia ventricosa)

机译：什么时候细胞不是细胞？一种将表皮细胞结构与室韦氏菌（Valonia ventricosa）的异常电生理联系起来的理论

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摘要

Ventricaria ventricosa and its relatives have intrigued cell biologists and electrophysiologists for over a hundred years. Historically, electrophysiologists have regarded V ventricosa as a large single plant cell with unusual characteristics including a small and positive vacuole-to-outside membrane potential difference. However, V ventricosa has a coenocytic construction, with an alveolate cytoplasm interpenetrated by a complex vacuole containing sulphated polysaccharides. We present a theory relating the coenocytic structure to the unusual electrophysiology of V ventricosa. The alveolate cytoplasm of V ventricosa consists of a collective of uninucleate cytoplasmic domains interconnected by fine cytoplasmic strands containing microtubules. The cytoplasm is capable of, disassociating into single cytoplasmic domains or aggregations of domains that can regenerate new coenocytes. The cytoplasmic domains are enclosed by outer (apical) and inner (basolateral) faces of a communal membrane with polarised K+-transporting functions, stabilised by microtubules and resembling a tissue such as a polarised epithelium. There is evidence for membrane trafficking through endocytosis and exocytosis and so "plasmalemma" and "tonoplast" do not have fixed identities. Intra- and extracellular polysaccharide mucilage has effects on electrophysiology through reducing the activity of water and through ion exchange. The vacuole-to-outside potential difference, at which the cell membrane conductance is maximal, reverses its sign from positive under hypertonic conditions to negative under hypotonic conditions. The marked mirror symmetry of the characteristics of current as a function of voltage and conductance as a function of voltage is interpreted as a feature of the communal membrane with polarised K+ transport. The complex inhomogeneous structure of the cytoplasm places in doubt previous measurements of cytoplasm-to-outside potential difference.
机译：怀氏弧菌及其亲属吸引了细胞生物学家和电生理学家一百多年了。从历史上看，电生理学家一直将V ventricosa视为具有单个特征的大型单个植物细胞，包括液泡与外部膜之间的电位差很小且为正值。然而，V ventricosa具有共胞质结构，其肺泡细胞质被含有硫酸化多糖的复杂液泡穿透。我们提出了一种理论，该理论将脑血管结构与V ventricosa的异常电生理学联系起来。 V.ventricosa的肺泡胞质由一组单核胞质域组成，这些域由包含微管的细胞质链相互连接。细胞质能够解离成单个细胞质结构域或结构域的聚集体，从而可以再生新的共细胞。胞质结构域被具有极化K +传输功能，由微管稳定并类似于诸如极化上皮的组织的公共膜的外表面（顶端）和内表面（基底外侧）所包围。有证据表明通过内吞作用和胞吐作用进行膜运输，因此“浆膜”和“液泡膜”没有固定的身份。细胞内和细胞外多糖黏液通过降低水的活性和离子交换对电生理产生影响。细胞膜电导最大的液泡-外电势差将其符号从高渗条件下的正反转为低渗条件下的负。电流特性作为电压的函数和电导率作为电压的函数的显着镜像对称性被解释为具有极化K +传输的公共膜的特征。细胞质复杂的不均匀结构使先前对细胞质与外部电位差的测量产生了疑问。

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