TY - JOUR A1 - Balazadeh, Salma A1 - Kwasniewski, Miroslaw A1 - Caldana, Camila A1 - Mehrnia, Mohammad A1 - Zanor, Maria Ines A1 - Xue, Gang-Ping A1 - Müller-Röber, Bernd T1 - ORS1, an H2O2-Responsive NAC Transcription Factor, Controls Senescence in Arabidopsis thaliana JF - Molecular plant N2 - We report here that ORS1, a previously uncharacterized member of the NAC transcription factor family, controls leaf senescence in Arabidopsis thaliana. Overexpression of ORS1 accelerates senescence in transgenic plants, whereas its inhibition delays it. Genes acting downstream of ORS1 were identified by global expression analysis using transgenic plants producing dexamethasone-inducible ORS1-GR fusion protein. Of the 42 up-regulated genes, 30 (similar to 70%) were previously shown to be up-regulated during age-dependent senescence. We also observed that 32 (similar to 76%) of the ORS1-dependent genes were induced by long-term (4 d), but not short-term (6 h) salinity stress (150 mM NaCl). Furthermore, expression of 16 and 24 genes, respectively, was induced after 1 and 5 h of treatment with hydrogen peroxide (H2O2), a reactive oxygen species known to accumulate during salinity stress. ORS1 itself was found to be rapidly and strongly induced by H2O2 treatment in both leaves and roots. Using in vitro binding site selection, we determined the preferred binding motif of ORS1 and found it to be present in half of the ORS1-dependent genes. ORS1 is a paralog of ORE1/ANAC092/AtNAC2, a previously reported regulator of leaf senescence. Phylogenetic footprinting revealed evolutionary conservation of the ORS1 and ORE1 promoter sequences in different Brassicaceae species, indicating strong positive selection acting on both genes. We conclude that ORS1, similarly to ORE1, triggers expression of senescence-associated genes through a regulatory network that may involve cross-talk with salt- and H2O2-dependent signaling pathways. KW - NAC transcription factor KW - leaf senescence KW - gene expression KW - gene regulatory network KW - hydrogen peroxide Y1 - 2011 U6 - https://doi.org/10.1093/mp/ssq080 SN - 1674-2052 VL - 4 IS - 2 SP - 346 EP - 360 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Winck, Flavia Vischi A1 - Kwasniewski, Miroslaw A1 - Wienkoop, Stefanie A1 - Müller-Röber, Bernd T1 - An optimized method for the isolation of nuclei from chlamydomas Reinhardtii (Chlorophyceae) JF - Journal of phycology N2 - The cell nucleus harbors a large number of proteins involved in transcription, RNA processing, chromatin remodeling, nuclear signaling, and ribosome assembly. The nuclear genome of the model alga Chlamydomonas reinhardtii P. A. Dang. was recently sequenced, and many genes encoding nuclear proteins, including transcription factors and transcription regulators, have been identified through computational discovery tools. However, elucidating the specific biological roles of nuclear proteins will require support from biochemical and proteomics data. Cellular preparations with enriched nuclei are important to assist in such analyses. Here, we describe a simple protocol for the isolation of nuclei from Chlamydomonas, based on a commercially available kit. The modifications done in the original protocol mainly include alterations of the differential centrifugation parameters and detergent-based cell lysis. The nuclei-enriched fractions obtained with the optimized protocol show low contamination with mitochondrial and plastid proteins. The protocol can be concluded within only 3 h, and the proteins extracted can be used for gel-based and non-gel-based proteomic approaches. KW - 2D gel electrophoresis KW - algae KW - Chlamydomonas KW - nuclear proteins KW - nucleus KW - proteomics Y1 - 2011 U6 - https://doi.org/10.1111/j.1529-8817.2011.00967.x SN - 0022-3646 VL - 47 IS - 2 SP - 333 EP - 340 PB - Wiley-Blackwell CY - Malden ER -