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Micrasterias as a Model System in Plant Cell Biology.

Lütz-Meindl U - Front Plant Sci (2016)

Bottom Line: The review focuses particularly on cell wall formation and composition, dictyosomal structure and function, cytoskeleton control of growth and morphogenesis as well as on ionic regulation and signal transduction.It has been also shown in the recent years that Micrasterias is a highly sensitive indicator for environmental stress impact such as heavy metals, high salinity, oxidative stress or starvation.This review is intended to summarize and discuss the most important results obtained in Micrasterias in the last 20 years and to compare the results to similar processes in higher plant cells.

View Article: PubMed Central - PubMed

Affiliation: Plant Physiology Division, Cell Biology Department, University of Salzburg Salzburg, Austria.

ABSTRACT
The unicellular freshwater alga Micrasterias denticulata is an exceptional organism due to its complex star-shaped, highly symmetric morphology and has thus attracted the interest of researchers for many decades. As a member of the Streptophyta, Micrasterias is not only genetically closely related to higher land plants but shares common features with them in many physiological and cell biological aspects. These facts, together with its considerable cell size of about 200 μm, its modest cultivation conditions and the uncomplicated accessibility particularly to any microscopic techniques, make Micrasterias a very well suited cell biological plant model system. The review focuses particularly on cell wall formation and composition, dictyosomal structure and function, cytoskeleton control of growth and morphogenesis as well as on ionic regulation and signal transduction. It has been also shown in the recent years that Micrasterias is a highly sensitive indicator for environmental stress impact such as heavy metals, high salinity, oxidative stress or starvation. Stress induced organelle degradation, autophagy, adaption and detoxification mechanisms have moved in the center of interest and have been investigated with modern microscopic techniques such as 3-D- and analytical electron microscopy as well as with biochemical, physiological and molecular approaches. This review is intended to summarize and discuss the most important results obtained in Micrasterias in the last 20 years and to compare the results to similar processes in higher plant cells.

No MeSH data available.


Related in: MedlinePlus

Transmission electron microscopy micrograph of abnormal cluster of dictyosomes induced by treatment of Micrasterias with CdSO4. Scale bar 1 μm.
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Figure 9: Transmission electron microscopy micrograph of abnormal cluster of dictyosomes induced by treatment of Micrasterias with CdSO4. Scale bar 1 μm.

Mentions: Among all metals tested on Micrasteriascadmium was the only one that, though extremely toxic to physiology and ultrastructure of the cells, was not compartmentalized intracellularly at all (Volland et al., 2011; Andosch et al., 2012). Cd is highly water soluble and enters aquatic ecosystems and soils mainly as consequence of anthropogenic activities such as disposal of electronic components. It represents a severe threat to human health by getting into the food chain via accumulation by plants (Templeton and Liu, 2010). Besides its severe negative implications on cell pattern formation, growth, photosynthetic activity and cell division (see above) it induces dictyosomal disintegration and autophagy in Micrasterias in concentrations of 150 μM (Andosch et al., 2012). Even a 1 h exposure to Cd resulted in a dramatic disturbance of ultrastructure, morphology and function of dictyosomes. The 11 cisternae of a control Golgi stack of Micrasterias were reduced to a maximum of 4 on the one hand, whereas on the other hand dictyosomal clusters that have completely lost their cis-trans-polarity (Figure 9) were found in Cd exposed cells. Vesicles were no longer found at the cisternal rims or in surrounding of the dictyosomes indicating a loss in secretion activity. The remaining inoperable dictyosomes consisted of only a few ring-shaped cisternae that were frequently surrounded by dilated ER cisternae (Andosch et al., 2012). Different stages of autophagosomes and autophagic vacuoles enclosing organelles, cytoplasmic portions or mucilage vesicles were present. Although cell viability was not affected, prolonged treatment with Cd for 1 day resulted in an almost complete depletion of dictyosomes in Micrasterias.


Micrasterias as a Model System in Plant Cell Biology.

Lütz-Meindl U - Front Plant Sci (2016)

Transmission electron microscopy micrograph of abnormal cluster of dictyosomes induced by treatment of Micrasterias with CdSO4. Scale bar 1 μm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4940373&req=5

Figure 9: Transmission electron microscopy micrograph of abnormal cluster of dictyosomes induced by treatment of Micrasterias with CdSO4. Scale bar 1 μm.
Mentions: Among all metals tested on Micrasteriascadmium was the only one that, though extremely toxic to physiology and ultrastructure of the cells, was not compartmentalized intracellularly at all (Volland et al., 2011; Andosch et al., 2012). Cd is highly water soluble and enters aquatic ecosystems and soils mainly as consequence of anthropogenic activities such as disposal of electronic components. It represents a severe threat to human health by getting into the food chain via accumulation by plants (Templeton and Liu, 2010). Besides its severe negative implications on cell pattern formation, growth, photosynthetic activity and cell division (see above) it induces dictyosomal disintegration and autophagy in Micrasterias in concentrations of 150 μM (Andosch et al., 2012). Even a 1 h exposure to Cd resulted in a dramatic disturbance of ultrastructure, morphology and function of dictyosomes. The 11 cisternae of a control Golgi stack of Micrasterias were reduced to a maximum of 4 on the one hand, whereas on the other hand dictyosomal clusters that have completely lost their cis-trans-polarity (Figure 9) were found in Cd exposed cells. Vesicles were no longer found at the cisternal rims or in surrounding of the dictyosomes indicating a loss in secretion activity. The remaining inoperable dictyosomes consisted of only a few ring-shaped cisternae that were frequently surrounded by dilated ER cisternae (Andosch et al., 2012). Different stages of autophagosomes and autophagic vacuoles enclosing organelles, cytoplasmic portions or mucilage vesicles were present. Although cell viability was not affected, prolonged treatment with Cd for 1 day resulted in an almost complete depletion of dictyosomes in Micrasterias.

Bottom Line: The review focuses particularly on cell wall formation and composition, dictyosomal structure and function, cytoskeleton control of growth and morphogenesis as well as on ionic regulation and signal transduction.It has been also shown in the recent years that Micrasterias is a highly sensitive indicator for environmental stress impact such as heavy metals, high salinity, oxidative stress or starvation.This review is intended to summarize and discuss the most important results obtained in Micrasterias in the last 20 years and to compare the results to similar processes in higher plant cells.

View Article: PubMed Central - PubMed

Affiliation: Plant Physiology Division, Cell Biology Department, University of Salzburg Salzburg, Austria.

ABSTRACT
The unicellular freshwater alga Micrasterias denticulata is an exceptional organism due to its complex star-shaped, highly symmetric morphology and has thus attracted the interest of researchers for many decades. As a member of the Streptophyta, Micrasterias is not only genetically closely related to higher land plants but shares common features with them in many physiological and cell biological aspects. These facts, together with its considerable cell size of about 200 μm, its modest cultivation conditions and the uncomplicated accessibility particularly to any microscopic techniques, make Micrasterias a very well suited cell biological plant model system. The review focuses particularly on cell wall formation and composition, dictyosomal structure and function, cytoskeleton control of growth and morphogenesis as well as on ionic regulation and signal transduction. It has been also shown in the recent years that Micrasterias is a highly sensitive indicator for environmental stress impact such as heavy metals, high salinity, oxidative stress or starvation. Stress induced organelle degradation, autophagy, adaption and detoxification mechanisms have moved in the center of interest and have been investigated with modern microscopic techniques such as 3-D- and analytical electron microscopy as well as with biochemical, physiological and molecular approaches. This review is intended to summarize and discuss the most important results obtained in Micrasterias in the last 20 years and to compare the results to similar processes in higher plant cells.

No MeSH data available.


Related in: MedlinePlus