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Chromatin associations in Arabidopsis interphase nuclei.

Schubert V, Rudnik R, Schubert I - Front Genet (2014)

Bottom Line: We found that chromatin fiber movement and variable associations, although in general relatively seldom, may occur between euchromatin segments along chromosomes, sometimes even over large distances.The combination of euchromatin segments bearing high or low co-expressing genes did not reveal different association frequencies probably due to adjacent genes of deviating expression patterns.Based on previous data and on FISH analyses presented here, we conclude that the global interphase chromatin organization in A. thaliana is relatively stable, due to the location of its 10 centromeres at the nuclear periphery and of the telomeres mainly at the centrally localized nucleolus.

View Article: PubMed Central - PubMed

Affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben Stadt Seeland, Germany.

ABSTRACT
The arrangement of chromatin within interphase nuclei seems to be caused by topological constraints and related to gene expression depending on tissue and developmental stage. In yeast and animals it was found that homologous and heterologous chromatin association are required to realize faithful expression and DNA repair. To test whether such associations are present in plants we analyzed Arabidopsis thaliana interphase nuclei by FISH using probes from different chromosomes. We found that chromatin fiber movement and variable associations, although in general relatively seldom, may occur between euchromatin segments along chromosomes, sometimes even over large distances. The combination of euchromatin segments bearing high or low co-expressing genes did not reveal different association frequencies probably due to adjacent genes of deviating expression patterns. Based on previous data and on FISH analyses presented here, we conclude that the global interphase chromatin organization in A. thaliana is relatively stable, due to the location of its 10 centromeres at the nuclear periphery and of the telomeres mainly at the centrally localized nucleolus. Nevertheless, chromatin movement enables a flexible spatial genome arrangement in plant nuclei.

No MeSH data available.


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CTs are mainly compact but allow relaxation, chromatin fiber out looping and association. (A) Scheme of chromosomes 1 and 5 showing the labeling of the euchromatic CT1top, CT1bottom and CT5bottom arm segments by FISH. (B) Arrows mark chromatin domains clearly located outside of their CTs in 2C nuclei. The left nucleus contains compact CTs of both homologs without external chromatin. (C) Minor (top arrow) and larger (bottom arrow) chromatin segments separated from CT1bottom arms in 4C nuclei. (D) Due to chromatin fiber out looping in this 4C nucleus, the homologous CT5bottom arms are connected (arrow).
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Figure 1: CTs are mainly compact but allow relaxation, chromatin fiber out looping and association. (A) Scheme of chromosomes 1 and 5 showing the labeling of the euchromatic CT1top, CT1bottom and CT5bottom arm segments by FISH. (B) Arrows mark chromatin domains clearly located outside of their CTs in 2C nuclei. The left nucleus contains compact CTs of both homologs without external chromatin. (C) Minor (top arrow) and larger (bottom arrow) chromatin segments separated from CT1bottom arms in 4C nuclei. (D) Due to chromatin fiber out looping in this 4C nucleus, the homologous CT5bottom arms are connected (arrow).

Mentions: A. thaliana chromosomes are organized in distinct CTs which are only seldom completely dispersed (Pecinka et al., 2004; Schubert et al., 2012). Here we show that after labeling CT1top, CT1bottom and CT5bottom in different colors by FISH also small or larger chromatin segments may be localized distantly apart from their compact CTs. Such chromatin fiber movements may also lead (once in 300 nuclei analyzed) to chromatin association between distantly located CTs by out-looping from their own CT (Figure 1).


Chromatin associations in Arabidopsis interphase nuclei.

Schubert V, Rudnik R, Schubert I - Front Genet (2014)

CTs are mainly compact but allow relaxation, chromatin fiber out looping and association. (A) Scheme of chromosomes 1 and 5 showing the labeling of the euchromatic CT1top, CT1bottom and CT5bottom arm segments by FISH. (B) Arrows mark chromatin domains clearly located outside of their CTs in 2C nuclei. The left nucleus contains compact CTs of both homologs without external chromatin. (C) Minor (top arrow) and larger (bottom arrow) chromatin segments separated from CT1bottom arms in 4C nuclei. (D) Due to chromatin fiber out looping in this 4C nucleus, the homologous CT5bottom arms are connected (arrow).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4230181&req=5

Figure 1: CTs are mainly compact but allow relaxation, chromatin fiber out looping and association. (A) Scheme of chromosomes 1 and 5 showing the labeling of the euchromatic CT1top, CT1bottom and CT5bottom arm segments by FISH. (B) Arrows mark chromatin domains clearly located outside of their CTs in 2C nuclei. The left nucleus contains compact CTs of both homologs without external chromatin. (C) Minor (top arrow) and larger (bottom arrow) chromatin segments separated from CT1bottom arms in 4C nuclei. (D) Due to chromatin fiber out looping in this 4C nucleus, the homologous CT5bottom arms are connected (arrow).
Mentions: A. thaliana chromosomes are organized in distinct CTs which are only seldom completely dispersed (Pecinka et al., 2004; Schubert et al., 2012). Here we show that after labeling CT1top, CT1bottom and CT5bottom in different colors by FISH also small or larger chromatin segments may be localized distantly apart from their compact CTs. Such chromatin fiber movements may also lead (once in 300 nuclei analyzed) to chromatin association between distantly located CTs by out-looping from their own CT (Figure 1).

Bottom Line: We found that chromatin fiber movement and variable associations, although in general relatively seldom, may occur between euchromatin segments along chromosomes, sometimes even over large distances.The combination of euchromatin segments bearing high or low co-expressing genes did not reveal different association frequencies probably due to adjacent genes of deviating expression patterns.Based on previous data and on FISH analyses presented here, we conclude that the global interphase chromatin organization in A. thaliana is relatively stable, due to the location of its 10 centromeres at the nuclear periphery and of the telomeres mainly at the centrally localized nucleolus.

View Article: PubMed Central - PubMed

Affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben Stadt Seeland, Germany.

ABSTRACT
The arrangement of chromatin within interphase nuclei seems to be caused by topological constraints and related to gene expression depending on tissue and developmental stage. In yeast and animals it was found that homologous and heterologous chromatin association are required to realize faithful expression and DNA repair. To test whether such associations are present in plants we analyzed Arabidopsis thaliana interphase nuclei by FISH using probes from different chromosomes. We found that chromatin fiber movement and variable associations, although in general relatively seldom, may occur between euchromatin segments along chromosomes, sometimes even over large distances. The combination of euchromatin segments bearing high or low co-expressing genes did not reveal different association frequencies probably due to adjacent genes of deviating expression patterns. Based on previous data and on FISH analyses presented here, we conclude that the global interphase chromatin organization in A. thaliana is relatively stable, due to the location of its 10 centromeres at the nuclear periphery and of the telomeres mainly at the centrally localized nucleolus. Nevertheless, chromatin movement enables a flexible spatial genome arrangement in plant nuclei.

No MeSH data available.


Related in: MedlinePlus