Exceptional Chromosome Regions Workshop I
References for Arabidopsis centromer studies
Greg Copenhaver & Daphne Pruess
- Copenhaver, G. P., Nickel, K., Kuromori, T., Benito, M-I., Kaul, S., Lin,
X., Bevan, M., Murphy, G., Harris, B., Parnell, L.D., McCombie, W.R., Martienssen,
R.A., Marra, M. and Preuss, D. (1999) Genetic Definition and Sequence Analysis
of Arabidopsis Centromeres. Science 286: 2468-74.
High precision genetic mapping was used to define the regions that contain
centromere functions on each natural chromosome in Arabidopsis thaliana.
These regions exhibited dramatic recombinational repression and contained
complex DNA surrounding large arrays of 180-bp repeats. Unexpectedly, the
DNA within the centromeres was not merely structural, but also encoded several
expressed genes. The regions flanking the centromeres were densely populated
by repetitive elements yet experienced normal levels of recombination. The
genetically defined centromeres were well conserved between Arabidopsis
ecotypes but displayed limited sequence homology between different chromosomes,
excluding repetitive DNA. This investigation provides a platform for dissecting
the role of individual sequences in higher eukaryotic centromeres
- Copenhaver, G.P. and Preuss, D. (1999) Centromeres in the genomic era:
Unraveling paradoxes. Curr. Op. Plant Biol. 2: 104-108.
The centromeres of higher plants and animals share many common features, though
current models fail to account for all aspects of centromere composition and
function. This dilemma will likely be resolved in the next few years in Arabidopsis
where robust assays for centromere function are available and the sequence
of the entire genome will be determined.
- Copenhaver, G.P., Browne, W.E. and Preuss, D. (1998 ) Assaying genome-wide
recombination and centromere functions with Arabidopsis tetrads. Proc.
Natl. Acad. Sci 95:247-252.
During meiosis, crossover events generate new allelic combinations, yet the
abundance of these genetic exchanges in individual cells has not been measured
previously on a genomic level. To perform a genome-wide analysis of recombination,
we monitored the assortment of genetic markers in meiotic tetrads from Arabidopsis.
By determining the number and distribution of crossovers in individual meiotic
cells, we demonstrate i) surprisingly precise regulation of crossover number
in each meiosis, ii) considerably reduced recombination along chromosomes
carrying ribosomal DNA arrays, and iii) an inversely proportional relationship
between recombination frequencies and chromosome size. This use of tetrad
analysis also achieved precise mapping of all five Arabidopsis centromeres,
localizing centromere functions in the intact chromosomes of a higher eukaryote.
Other relevant references:
- Copenhaver, G.P., Doelling, J.H., Gens, S.J., Pikaard, C.S. (1995) Use of
RFLPs larger than 100 kbp to map the position and internal organization of
the nucleolus organizer region on chromosome 2 in Arabidopsis thaliana.
The Plant Journal 7(2): 273-286.
- Copenhaver, G.P., and Pikaard, C.S. (1996) RFLP and physical mapping with
an rDNA-specific endonuclease reveals that nucleolus organizer regions of
Arabidopsis thaliana adjoin the telomeres on chromosomes 2 and 4.The
Plant Journal 9(2): 259-272.
- Copenhaver, G.P. and Pikaard, C.S. (1996) Two-dimensional RFLP analyses
reveal megabase-sized clusters of rRNA gene variants in Arabidopsis thaliana,
suggesting local spreading of variants as the mode for gene homogenization
during concerted evolution. The Plant Journal 9(2): 273-282.
Wednesday, October 22, 2003
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