Poster: Cell Cycle & Cytokinesis
Abs #
1090: Structural defects of male meiotic chromosomes in the ask1-1 mutant of Arabidopsis
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Presenter: |
Yang, Ming , yming@okstate.edu | Authors | Yang, Ming (A) Wang, Yixing (A) Wu, Hong (A) (B) Liang, Genqing (A) | | Affiliations: |
(A): Department of Botany, Oklahoma State University
(B): South China Agricultural University, Guangzhou 510642, Guangdong, P. R. China
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| Web Site: | http://plantbionet.okstate.edu/faculty/myang.html | |
Recombination nodules (RNs) and synaptonemal complexes (SCs) are essential for the synapsis of homologous chromosomes in most eukaryotes during meiosis. RNs and SCs normally must be removed during prophase I in order for homologous chromosomes to separate. Little is known about what proteins regulate the removal of proteins that link homologous chromosomes. Here we report the characterization of structural defects on male meiotic chromosomes in the arabidopsis skp1-like1 (ask1-1) mutant. We observed in ask1-1 by fluorescence microscopy that the chromosomes differed in morphology with those in the wild type (WT) in prophase I, the bivalents exhibited non-disjunction in prophase II, and a subset of the chromosomes remained associated during anaphase II. By transmission electron microscopy we revealed in ask1-1 that there were more RNs in the microsporocytes than in the WT, the SCs were deformed, and there were persistent recombination nodule-like structures (RNLs) associated with the chromosomes in the later stages of male meiosis. By isolating and analyzing RNA samples from microsporocytes or tetrads at the different cell cycle stages, we found that ASK1 was transcribed throughout male meiosis in the WT, and ASK1 and its closest homologue ASK2 did not overlap in transcription during prophase I but overlapped afterwards. Based on these findings and on the fact that ASK1 is a component of the SCF ubiquitin ligase, we hypothesize that ASK1 regulates the degradation of RNs and RNLs that preferentially link two homologous non-sister chromatids within each bivalent during male meiosis in Arabidopsis.
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