1,721,164 research outputs found
Assembly and disassembly of plant microtubules: tubulin modifications and binding to MAPs
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The "stop-and-go" movement of Golgi stacks: illuminating the dynamic association between membranes and cytoskeleton
No full textThe manuscript by Nebenführ and coworkers showed that the plant Golgi bodies move along actin filaments and that transport occurs in a way called as "stop-and-go". This means that Golgi bodies can move along actin filaments but they can also temporarily stop at precise locations in the plant cell. Constant transport guarantees that Golgi bodies are uniformly distributed in the cell, while the stop phase is required for production of vesicles at specific sites. Using techniques of protein engineering (cloning the GmMan1 gene, which encodes the resident Golgi protein á-1,2 mannosidase I, and fusing it with GFP) the authors labeled specifically the Golgi bodies and were able to visualize the movement of Golgi stacks in living BY-2 cells. The Golgi stacks performed a "stop-and-go" movement, in which directed movement is dependent on cytoplasmic streaming occurring along actin microfilaments. Authors also observed that microtubule-disrupting drugs had a stimulatory effect on organelle streaming. Nebenführ and coworkers suggested a model in which the "stop-and-go" movement of Golgi units along actin filaments is regulated by stop messages produced by the endoplasmic reticulum. The stop signals are used to optimize the interaction between Golgi and ER in order to regulate the trafficking of proteins from membrane compartments to the cell wall. Observation of moving Golgi bodies in the plant cell revealed a phenomenon that was already been predicted previously but never described before. I would like to support this article for the special issue of Plant Physiology dedicated to the celebration of the 25,000th published Article. As I work in related fields, I found the manuscript of Nebenführ and coworkers fascinating and highly motivating. The possibility to observe Golgi bodies while moving along actin filaments in living cells opened enormous prospective of research and provided critical information on the dynamic interactions between plant cell organelles and the cytoskeleton, a process that also controls critical aspects of the plant cell (such as shape and growth direction). Following this manuscript, other papers have shown the movement of different organelle classes (such as endosomes and secretory vesicles) in living plant cells. Transport of proteins from ER to Golgi and then to the cell wall matrix is an important process because it is used by plant cells to regulate the secretion of enzymes that construct the cell wall polysaccharides thus determining the shape and growth direction of the cell. Understanding the molecular mechanism of this process is fundamental for realizing how a plant cell coordinates the cytoskeletal activity with membrane trafficking and cell wall construction
The legacy of kinesins in the pollen tube 30 years later
Full text linkThe pollen tube is fundamental in the reproduction of seed plants. Particularly in angiosperms, we now have much information about how it grows, how it senses extracellular signals, and how it converts them into a directional growth mechanism. The expansion of the pollen tube is also related to dynamic cytoplasmic processes based on the cytoskeleton (such as polymerization/depolymerization of microtubules and actin filaments) or motor activity along with the two cytoskeletal systems and is dependent on motor proteins. While a considerable amount of information is available for the actomyosin system in the pollen tube, the role of microtubules in the transport of organelles or macromolecular structures is still quite uncertain despite that 30 years ago the first work on the presence of kinesins in the pollen tube was published. Since then, progress has been made in elucidating the role of kinesins in plant cells. However, their role within the pollen tube is still enigmatic. In this review, I will postulate some roles of kinesins in the pollen tube 30 years after their initial discovery based on information obtained in other plant cells in the meantime. The most concrete hypotheses predict that kinesins in the pollen tube enable the short movement of specific organelles or contribute to generative cell or sperm cell transport, as well as mediate specific steps in the process of endocytosis
Rethinking cytoskeleton in plant reproduction: toward a biotechnological future?
No full textSexual reproduction in plants is intimately
connected to the activity of the cytoskeletal apparatus in
reproductive cells. Because of the ease with which the
pollen tube can be studied, it has become a model for
studying many aspects of cell physiology related to the
cytoskeleton, such as movement of organelles and vesicles
and cell division. However, information about cytoskeletal
proteins is still insufficient for determining cytoskeletal
functions during reproduction, especially in
terms of cell-cell interactions. One reason may be that
cytological and biochemical research on the cytoskeleton
of pollen and the embryo sac has not been complemented
by sufficient research activity at genetic and molecular
levels, and few laboratories are currently involved in
this work. This might be because of problems in identifying
appropriate applied applications of the work that
might attract more investigation
Pollen priming for more efficient reproduction in a heating world: what we know, what we need to know
No full textGlobal warming is predicted to alter temperatures thereby leading to a significant loss in crop productivity and yield. One target of global warming is plant sexual reproduction, which will be deeply threatened by high temperatures because the male gametophyte (the pollen) is particularly susceptible to heat stress. As a reaction to the latter, pollen enacts many responses that involve specific reprogramming of genetic, metabolic, and cellular activities. Most published works focus on a single episode of heat stress but less is known about the effects of heat pre-exposure (priming) on acquired thermotolerance (ATT). The purpose of this review is to gain a deeper understanding of ATT mechanisms in pollen and pollen tube, primarily from available literature. In particular, we will examine many facets (cell wall, cytoskeleton, ion fluxes, reactive oxygen species, etc.) that could be both targets of heat stress and active responses to priming
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