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  • Kinetochore individualization in meiosis I is required for centromeric cohesin removal in meiosis II.

Kinetochore individualization in meiosis I is required for centromeric cohesin removal in meiosis II.

The EMBO journal (2021-03-02)
Yulia Gryaznova, Leonor Keating, Sandra A Touati, Damien Cladière, Warif El Yakoubi, Eulalie Buffin, Katja Wassmann

Partitioning of the genome in meiosis occurs through two highly specialized cell divisions, named meiosis I and meiosis II. Step-wise cohesin removal is required for chromosome segregation in meiosis I, and sister chromatid segregation in meiosis II. In meiosis I, mono-oriented sister kinetochores appear as fused together when examined by high-resolution confocal microscopy, whereas they are clearly separated in meiosis II, when attachments are bipolar. It has been proposed that bipolar tension applied by the spindle is responsible for the physical separation of sister kinetochores, removal of cohesin protection, and chromatid separation in meiosis II. We show here that this is not the case, and initial separation of sister kinetochores occurs already in anaphase I independently of bipolar spindle forces applied on sister kinetochores, in mouse oocytes. This kinetochore individualization depends on separase cleavage activity. Crucially, without kinetochore individualization in meiosis I, bivalents when present in meiosis II oocytes separate into chromosomes and not sister chromatids. This shows that whether centromeric cohesin is removed or not is determined by the kinetochore structure prior to meiosis II.

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Product Description

Dimethyl sulfoxide, Hybri-Max, sterile-filtered, BioReagent, suitable for hybridoma, ≥99.7%
Triton X-100, for molecular biology
DL-Dithiothreitol, for molecular biology, ≥98% (HPLC), ≥99% (titration)
Propidium iodide solution, solution (1.0 mg/ml in water)
Mineral oil, light oil
Formaldehyde solution, contains 10-15% methanol as stabilizer, 37 wt. % in H2O
N6,2′-O-Dibutyryladenosine 3′,5′-cyclic monophosphate sodium salt, ≥97% (HPLC), powder
Paraformaldehyde, prilled, 95%
Anti-α-Tubulin−FITC antibody, Mouse monoclonal, clone DM1A, purified from hybridoma cell culture
(+)-S-Trityl-L-cysteine, 97%
Anti-PP2A, C subunit Antibody, clone 1D6, Alexa Fluor® 488 Conjugate, clone 1D6, from mouse, ALEXA FLUOR® 488