Sexual reproduction in eukaryotes requires the creation of haploid
gametes from diploid cells by a specialized cell division called meiosis. Correct
alignment and orientation of the homologues on the meta phase I plate is crucial
for the correct reductional segregation of chromosomes during meiosis. In most
organisms, homologue alignment is concurrent with, although distinct from, a
process called synapsis, which is the close association between the homologues
within the context of a proteinaceous structure formed along the entire length of
the chromosome, called the synaptonemal complex (SC).
The model yeast system Sehizosaeeharomyees pombe exhibits an SC-free
meiosis. In S. pombe, proteinaceous structures termed linear elements (LinEs)
are formed, which vary in length and are classified accordingly. A major
component of LinEs is the Rec10 protein. Different mutations in the rec10 gene
result in distinct defects in the formation and/or development of LinEs alongside
varying effects on meiotic recombination.
In this study, we demonstrate the temporal order of LinE formation and
maturation, correlated with Rad51 and Hop1 localisation. Cytological analysis of
Hop1 localisation revealed the presence of as yet unidentified structures.
A multiple sequence alignment of the C-terminal domain of Rec10 with
axial proteins of other organisms exhibited domain homology, with some
residues being highly conserved. Based on this, this study generated several
rec10 mutants exhibiting different point mutations within the C-terminal domain
of rec10. In this study we analysed the temporal profile of LinE development and
the recombination proficiency of these mutants.
This study analysed the temporal profile of LinE development in mutants
of LinE-associated proteins, previously demonstrated as having altered LinE
formation; demonstrating that Rec27 is not required for initiation of LinE
formation, as previously proposed.
In addition, we present data that is in agreement with the regions of
crossover preference model. We also analyse LinE formation in several rec10
heterozygous diploids, demonstrating semi-dominance of some rec10 mutant
alleles.