Long-distant transport in characean algae

溶质的跨细胞渗透和长距离运输尤为重要，因为它们将光合同化物输送到生长的细胞中，并使多细胞生物发育过程中涉及的信号物质得以运输。这些运输机制强烈依赖于细胞质的力学和粘弹性特性。近年来，各种生物和人工系统中主动转运的研究成为人们关注的热点。特别是，主动系统的自组装和集体行为在整个长度尺度上似乎有许多相似之处。了解这些现象在生物系统中的生理相关性是必不可少的。特征藻类提供了一个独特的机会来研究在几厘米的长度尺度上的循环驱动的细胞间运输。在这个提议中，我们将探索特征细胞链中的长距离运输，并了解细胞质的粘弹性特性如何决定可变条件下光代谢产物的运输。我们将使用磁性纳米/微粒子和磁性乳剂来测量粘弹性响应和靶向细胞质中的生物活性物质。这将使我们能够建立细胞质流变学与外部pH （pH带）异质性形成和光合活性之间的关系。将开发一种新的无创方法来研究自然产生的光代谢物的胞间质渗透，并阐明细胞间电导调节的生理手段。我们打算确定在具有不同适应环境渗透机制的物种中，胞间连丝的渗透性如何取决于循环速度和盐度胁迫的存在。此外，我们希望阐明循环电流在细胞间通讯和具有各种光合作用的结构形成中的作用。

Transcellular permeation and long-distance transport of solutes are particularly important because they deliver the photosynthetic assimilates to growing cells and enable trafficking of signalling substances involved in the development of multicellular organisms. These transport mechanisms strongly rely on the mechanical and viscoelastic properties of the cellular cytoplasm. In recent years, studies of active transport in various biological and artificial systems become a focus of intensive research. In particular, self-assembly and collective behaviour of active systems appear to have many similarities across the lengthscales. Understanding the physiological relevance of those phenomena in biological systems is essential. Characean algae provide a unique opportunity to study cyclosis-driven intercellular transport on the length scale of a few centimetres. In this proposal, we are going to explore the long-distant transport in characean cell chains and understand how the viscoelastic properties of the cytoplasm determine the transport of photo-metabolites under variable conditions. We are going to employ magnetic nano/microparticles and magnetic emulsions for measurement of the viscoelastic response and targeting biologically active materials in the cytoplasm. This will allow us to establish the relation between the rheology of the cytoplasm and the formation of the heterogeneities in the external pH (pH bands) and the photosynthetic activity. A new noninvasive method will be developed to study the plasmodesmal permeation by naturally produced photometabolites and to elucidate the physiological means for modulation of cell-to-cell conductance. We intend to establish how the permeability of the plasmodesmata depends on the cyclosis velocity and the presence of the salinity stress in the species with different mechanisms of adaptation to the environment osmoticity. Furthermore, we expect to clarify the role of the circulating electric currents in intercellular communications and formation of structures with various photosynthetic activities.