Journal of Cell Science 116, e903 (2003)
Copyright © 2003 The Company of Biologists Limited
Linear elements help chromosomes pair up
Meiosis in fission yeast has several unusual features. One is the presence
of `linear elements' rather than synaptonemal complexes (SCs) on paired
homologous chromosomes. These resemble the axial elements that appear prior to
SCs in other organisms but lack the central region that connects chromosomes
in the mature SC. Since little is known about the assembly and function of
linear elements, Jürg Kohli and co-workers have studied their formation
in a group of meiotic-recombination-deficient (rec) mutants,
combining EM work with analyses of chromosome pairing in cells containing
GFP-labelled chromosomes (see p.
1719). The authors find that linear elements can form in
rec12 mutants, which cannot generate recombination-initiating
double-stranded breaks (DSBs), but are significantly altered in rec8
and rec11 mutants, which lack meiotic cohesins. Cohesion but not DSB
formation is thus a prerequisite for efficient assembly of linear elements.
Interestingly, Kohli and co-workers observe that rec10 mutants lack
linear elements entirely. These cells exhibit normal sister chromatid cohesion
but compromised homologous chromosome pairing away from the centromere. The
authors therefore propose that linear elements promote pairing of interstitial
arm regions of chromosomes but that alternative mechanisms underpin pairing
elsewhere.
Related articles in JCS:
- Linear element formation and their role in meiotic sister chromatid cohesion and chromosome pairing
- Monika Molnar, Eveline Doll, Ayumu Yamamoto, Yasushi Hiraoka, and Jürg Kohli
JCS 2003 116: 1719-1731.
[Abstract]
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