title: The biphasic interphase-mitotic polarity of cell nuclei induced under DNA replication stress seems to be correlated with Pin2 localization in root meristems of Allium cepa.
abstract: Long-term treatment of Allium cepa seedlings with low concentration of hydroxyurea (HU) results in a disruption of cell cycle checkpoints, leading root apex meristem (RAM) cells to an abnormal organization of nuclear structures forming interphase (I) and mitotic (M) domains of chromatin at opposite poles of the nucleus. Thus far, both critical cell length and an uneven distribution of cyclin B-like proteins along the nuclear axis have been recognized as essential factors needed to facilitate the formation of biphasic interphase-mitotic (IM) cells. Two new aspects with respect to their emergence are investigated in this study. The first concerns a relationship between the polarity of increasing chromatin condensation (IM orientation) and the acropetal (base→apex) alignment of RAM cell files. The second problem involves the effects of auxin (IAA), on the frequency of IM cells. We provide evidence that there is an association between the advanced M-poles of the IM cell nuclei and the polarized accumulation sites of auxin efflux carriers (PIN2 proteins) and IAA. Furthermore, our observations reveal exclusion regions for PIN2 proteins in the microtubule-rich structures, such as preprophase bands (PPBs) and phragmoplast. The current and previous studies have prompted us to formulate a hypothetical mechanism linking PIN2-mediated unilateral localization of IAA and the induction of bipolar IM cells in HU-treated RAMs of A. cepa.
authors.affiliation: Department of Cytophysiology, Faculty of Biology and Environmental Protection, University of Łódź, Pomorska 141/143, 90-236 Łódź, Poland. Electronic address: zabkka@poczta.onet.pl.
authors.forename: Aneta
authors.initials: A
authors.lastname: Żabka
authors.affiliation: Laboratory of Molecular and Systemic Neuromorphology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Pasteura 3, 02-093 Warsaw, Poland. Electronic address: p.trzaskoma@gmail.com.
authors.forename: Paweł
authors.initials: P
authors.lastname: Trzaskoma
authors.affiliation: Department of Cytophysiology, Faculty of Biology and Environmental Protection, University of Łódź, Pomorska 141/143, 90-236 Łódź, Poland. Electronic address: winnicki@biol.uni.lodz.pl.
authors.forename: Konrad
authors.initials: K
authors.lastname: Krajewski
authors.affiliation: Department of Cytophysiology, Faculty of Biology and Environmental Protection, University of Łódź, Pomorska 141/143, 90-236 Łódź, Poland. Electronic address: justpoli@biol.uni.lodz.pl.
authors.forename: Justyna Teresa
authors.initials: JT
authors.lastname: Polit
authors.affiliation: Department of Cytophysiology, Faculty of Biology and Environmental Protection, University of Łódź, Pomorska 141/143, 90-236 Łódź, Poland. Electronic address: agnieszka_chmielnicka@wp.pl.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Chmielnicka
authors.affiliation: Department of Cytophysiology, Faculty of Biology and Environmental Protection, University of Łódź, Pomorska 141/143, 90-236 Łódź, Poland. Electronic address: jamasz@biol.uni.lodz.pl.
authors.forename: Janusz
authors.initials: J
authors.lastname: Maszewski
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D016764:Cell Polarity / Q000187:drug effects; D004261:DNA Replication / Q000187:drug effects; D005455:Fluorescent Antibody Technique; D006918:Hydroxyurea / Q000494:pharmacology; D007210:Indoleacetic Acids / Q000494:pharmacology; D007399:Interphase / Q000187:drug effects; D018519:Meristem / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism; D008938:Mitosis / Q000187:drug effects; D008954:Models, Biological; D019697:Onions / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*; D011418:Prophase; D021381:Protein Transport / Q000187:drug effects; D013312:Stress, Physiological / Q000187:drug effects
chemical_list: D029681:Arabidopsis Proteins; D006918:Hydroxyurea; D007210:Indoleacetic Acids; D010940:Plant Proteins; C117013:AT5G57090 protein, Arabidopsis; C030737:indoleacetic acid
keywords: Biphasic nuclei; Cell cycle; DNA replication stress; Hydroxyurea; IAA; PIN2