Sequential loading of cohesin subunits during the first meiotic prophase of grasshoppers.

The cohesin complexes play a key role in chromosome segregation during both mitosis and meiosis. They establish sister chromatid cohesion between duplicating DNA molecules during S-phase, but they also have an important role during postreplicative double-strand break repair in mitosis, as well as during recombination between homologous chromosomes in meiosis. An additional function in meiosis is related to the sister kinetochore cohesion, so they can be pulled by microtubules to the same pole at anaphase I.

Mammalian SGO2 appears at the inner centromere domain and redistributes depending on tension across centromeres during meiosis II and mitosis.

Shugoshin (SGO) is a family of proteins that protect centromeric cohesin complexes from release during mitotic prophase and from degradation during meiosis I. Two mammalian SGO paralogues - SGO1 and SGO2 - have been identified, but their distribution and function during mammalian meiosis have not been reported. Here, we analysed the expression of SGO2 during male mouse meiosis and mitosis.

Drosophila cohesins DSA1 and Drad21 persist and colocalize along the centromeric heterochromatin during mitosis.

Sister chromatid cohesion in eukaryotes is maintained mainly by a conserved multiprotein complex termed cohesin. Drad21 and DSA1 are the Drosophila homologues of the yeast Scc1 and Scc3 cohesin subunits, respectively. We recently identified a Drosophila mitotic cohesin complex composed of Drad21/DSA1/DSMC1/DSMC3.

Depletion of Drad21/Scc1 in Drosophila cells leads to instability of the cohesin complex and disruption of mitotic progression.

Background: The coordination of cell cycle events is necessary to ensure the proper duplication and dissemination of the genome. In this study, we examine the consequences of depleting Drad21 and SA, two non-SMC subunits of the cohesin complex, by dsRNA-mediated interference in Drosophila cultured cells.

Results: We have shown that a bona fide cohesin complex exists in Drosophila embryos.

Expression and behaviour of CENP-E at kinetochores during mouse spermatogenesis.

Centromere protein E (CENP-E) is a microtubule motor protein localised in the outer kinetochore plate and in the fibrous corona that relocalises to the midzone in early anaphase. While its expression in somatic cells has been widely analysed, an accurate description of its behaviour during the two meiotic divisions has not yet been reported. We have carefully analysed by immunofluorescence the subcellular distribution of CENP-E during mouse spermatogenesis.