The Rlm1 transcription factor is a target of the cell wall integrity pathway. We report that an Δ mutant grown on a nonfermentable carbon source at low osmolarity forms cell groups in which a mother cell is surrounded by smaller "satellite-daughter" cells. Mother cells in these groups progressed through repeated rounds of cell division with normal rates of bud growth and genetic stability; however, these cells underwent precocious START relative to wild-type mothers. Thus, once activated, Rlm1 delays the transition from G to S, a mechanism we term the cell wall/START (CW/START) checkpoint. The Δ satellite-cell phenotype is suppressed by deletion of either , which encodes the kinase that activates Rlm1, or , which is also activated by Slt2; suggesting that Slt2 can have opposing roles in regulating the START transition. Consistent with an Rlm1-dependent CW/START checkpoint, Δ satellite daughters were unable to grow or divide further even after transfer to rich medium, but UV irradiation in G could partially rescue Δ satellite daughters in the next division. Indeed, after cytokinesis, these satellite daughters shrank rapidly, displayed amorphous actin staining, and became more permeable. As a working hypothesis, we propose that duplication of an "actin-organizing center" in late G may be required both to progress through START and to reestablish the actin cytoskeleton in daughter cells.
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http://dx.doi.org/10.1534/genetics.117.204206 | DOI Listing |
Gene
October 2023
Pritzker Laboratory for Molecular Systematics and Evolution, Field Museum of Natural History, Chicago, Illinois, USA.
The Lemon shark Negaprion brevirostris is an important species experiencing conservation issues that is in need of genomic resources. Herein, we conducted a genome survey sequencing in N. brevirostris and determined genome size, explored repetitive elements, assembled and annotated the 45S rRNA DNA operon and mitochondrial genome.
View Article and Find Full Text PDFAn Acad Bras Cienc
September 2024
Universidade Federal de Mato Grosso, Departamento de Botânica e Ecologia, Instituto de Biociências, Laboratório de Estudos Integrados de Plantas, Av. Fernando Correa da Costa, 2375, 78060-900 Cuiabá, MT, Brazil.
Repetitive sequences can lead to variation in DNA quantity and composition among species. The Orchidaceae, the largest angiosperm family, is divided into five subfamilies, with Apostasioideae as the basal group and Orchidoideae and Epidendroideae showing high diversification rates. Despite their different evolutionary paths, some species in these groups have similar nuclear DNA content.
View Article and Find Full Text PDFJ Exp Bot
September 2024
Department of Biology and the Skidmore Microscopy Imaging Center, Skidmore College, Saratoga Springs, NY, 12866, USA.
Penium margaritaceum, a unicellular zygnematophyte (Streptophyta), was employed to elucidate changes in cell expansion when cells were challenged with the fungal pectinolytic enzyme, pectate lyase, and/or the microtubule disrupting agent, amiprophos-methyl (APM). Microtubule disruption by APM results in significant swelling at expansion zones. These swollen zones provide an easy marker for the location of expansion zones, particularly in cells with altered cell wall pectin.
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