Limits...
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

3-D reconstruction of Micrasterias dictyosomes from FIB-SEM series.Cis-side in red, trans-side in green. (A) The entire dictyosome is enwrapped by ER envelope (blue) (scale bar is 1 μm). (B) Detail of another dictyosome showing the close spatial interaction between dictyosomal cisternae and the ER. Mucilage vesicles in white, multivesicular bodies in yellow (scale bar is 1 μm). Reprinted with permission from Lütz-Meindl et al. (2015), (A) Copyright© 2015 Royal Microscopical Society and from Wanner et al. (2013)(B), Copyright© 2013 Elsevier Inc.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4940373&req=5

Figure 5: 3-D reconstruction of Micrasterias dictyosomes from FIB-SEM series.Cis-side in red, trans-side in green. (A) The entire dictyosome is enwrapped by ER envelope (blue) (scale bar is 1 μm). (B) Detail of another dictyosome showing the close spatial interaction between dictyosomal cisternae and the ER. Mucilage vesicles in white, multivesicular bodies in yellow (scale bar is 1 μm). Reprinted with permission from Lütz-Meindl et al. (2015), (A) Copyright© 2015 Royal Microscopical Society and from Wanner et al. (2013)(B), Copyright© 2013 Elsevier Inc.

Mentions: Dictyosomes of Micrasterias are unique organelles measuring 2–3 μm in diameter and revealing a constant number of 11 cisternae independent from the stage of the cell cycle. They are thus many times larger than in higher plant cells or in other algae (see also Lütz-Meindl et al., 2015). In growing cells they are located in great number around the nucleus and along the chloroplast membrane. Like in higher plant cells (see e.g., Hawes and Satiat-Jeunemaitre, 2005) they have been shown to be associated with a cis-located ER cisternae in TEM. A recent study using focused ion beam milling and block face imaging by field emission scanning electron microscopy (FIB-SEM) has yielded first information on the 3-D architecture of Golgi stacks in M. denticulata (Wanner et al., 2013). This method allows 3-D reconstruction of large cytoplasmic volumes up to several hundred μm3 by 5–10 nm serial slicing. FIB-SEM series and 3-D reconstruction of high pressure frozen and cryo-substituted Micrasterias cells showed that the dictyosomes are not only associated with a cis-ER cisternae but are surrounded by a huge trans-side located ER sheath leading to an almost entire ER envelope around them (Figures 5A,B).


Micrasterias as a Model System in Plant Cell Biology.

Lütz-Meindl U - Front Plant Sci (2016)

3-D reconstruction of Micrasterias dictyosomes from FIB-SEM series.Cis-side in red, trans-side in green. (A) The entire dictyosome is enwrapped by ER envelope (blue) (scale bar is 1 μm). (B) Detail of another dictyosome showing the close spatial interaction between dictyosomal cisternae and the ER. Mucilage vesicles in white, multivesicular bodies in yellow (scale bar is 1 μm). Reprinted with permission from Lütz-Meindl et al. (2015), (A) Copyright© 2015 Royal Microscopical Society and from Wanner et al. (2013)(B), Copyright© 2013 Elsevier Inc.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 5: 3-D reconstruction of Micrasterias dictyosomes from FIB-SEM series.Cis-side in red, trans-side in green. (A) The entire dictyosome is enwrapped by ER envelope (blue) (scale bar is 1 μm). (B) Detail of another dictyosome showing the close spatial interaction between dictyosomal cisternae and the ER. Mucilage vesicles in white, multivesicular bodies in yellow (scale bar is 1 μm). Reprinted with permission from Lütz-Meindl et al. (2015), (A) Copyright© 2015 Royal Microscopical Society and from Wanner et al. (2013)(B), Copyright© 2013 Elsevier Inc.
Mentions: Dictyosomes of Micrasterias are unique organelles measuring 2–3 μm in diameter and revealing a constant number of 11 cisternae independent from the stage of the cell cycle. They are thus many times larger than in higher plant cells or in other algae (see also Lütz-Meindl et al., 2015). In growing cells they are located in great number around the nucleus and along the chloroplast membrane. Like in higher plant cells (see e.g., Hawes and Satiat-Jeunemaitre, 2005) they have been shown to be associated with a cis-located ER cisternae in TEM. A recent study using focused ion beam milling and block face imaging by field emission scanning electron microscopy (FIB-SEM) has yielded first information on the 3-D architecture of Golgi stacks in M. denticulata (Wanner et al., 2013). This method allows 3-D reconstruction of large cytoplasmic volumes up to several hundred μm3 by 5–10 nm serial slicing. FIB-SEM series and 3-D reconstruction of high pressure frozen and cryo-substituted Micrasterias cells showed that the dictyosomes are not only associated with a cis-ER cisternae but are surrounded by a huge trans-side located ER sheath leading to an almost entire ER envelope around them (Figures 5A,B).

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