Proteasomal degradation of BRAHMA promotes Boron tolerance in Arabidopsis

High levels of boron (B) induce DNA double-strand breaks (DSBs) in eukaryotes, including plants. Here we show a molecular pathway of high B-induced DSBs by characterizing Arabidopsis thaliana hypersensitive to excess boron mutants. Molecular analysis of the mutants revealed that degradation of a SWItch/Sucrose Non-Fermentable subunit, BRAHMA (BRM), by a 26S proteasome (26SP) with specific subunits is a key process for ameliorating high-B-induced DSBs. We also found that high-B treatment induces histone hyperacetylation, which increases susceptibility to DSBs. BRM binds to acetylated histone residues and opens chromatin. Accordingly, we propose that the 26SP limits chromatin opening by BRM in conjunction with histone hyperacetylation to maintain chromatin stability and avoid DSB formation under high-B conditions. Interestingly, a positive correlation between the extent of histone acetylation and DSB formation is evident in human cultured cells, suggesting that the mechanism of DSB induction is also valid in animals

Primed histone demethylation regulates shoot regenerative competency

Acquisition of pluripotency by somatic cells is a striking process that enables multicellular organisms to regenerate organs. This process includes silencing of genes to erase original tissue memory and priming of additional cell type specification genes, which are then poised for activation by external signal inputs. Here, through analysis of genome-wide histone modifications and gene expression profiles, we show that a gene priming mechanism involving LYSINE-SPECIFIC DEMETHYLASE 1-LIKE 3 (LDL3) specifically eliminates H3K4me2 during formation of the intermediate pluripotent cell mass known as callus derived from Arabidopsis root cells. While LDL3-mediated H3K4me2 removal does not immediately affect gene expression, it does facilitate the later activation of genes that act to form shoot progenitors when external cues lead to shoot induction. These results give insights into the role of H3K4 methylation in plants, and into the primed state that provides plant cells with high regenerative competency

Primed histone demethylation regulates shoot regenerative competency

Acquisition of pluripotency by somatic cells is a striking process that enables multicellular organisms to regenerate organs. This process includes silencing of genes to erase original tissue memory and priming of additional cell type specification genes, which are then poised for activation by external signal inputs. Here, through analysis of genome-wide histone modifications and gene expression profiles, we show that a gene priming mechanism involving LYSINE-SPECIFIC DEMETHYLASE 1-LIKE 3 (LDL3) specifically eliminates H3K4me2 during formation of the intermediate pluripotent cell mass known as callus derived from Arabidopsis root cells. While LDL3-mediated H3K4me2 removal does not immediately affect gene expression, it does facilitate the later activation of genes that act to form shoot progenitors when external cues lead to shoot induction. These results give insights into the role of H3K4 methylation in plants, and into the primed state that provides plant cells with high regenerative competency

Topical insulin-like growth factor 1 treatment using gelatin hydrogels for glucocorticoid-resistant sudden sensorineural hearing loss: a prospective clinical trial

<p>Abstract</p> <p>Background</p> <p>Sudden sensorineural hearing loss (SSHL) is a common condition in which patients lose the hearing in one ear within 3 days. Systemic glucocorticoid treatments have been used as standard therapy for SSHL; however, about 20% of patients do not respond. We tested the safety and efficacy of topical insulin-like growth factor 1 (IGF1) application using gelatin hydrogels as a treatment for SSHL.</p> <p>Methods</p> <p>Patients with SSHL that showed no recovery to systemic glucocorticoid administration were recruited. We applied gelatin hydrogels, impregnated with recombinant human IGF1, into the middle ear. The primary outcome measure was the proportion of patients showing hearing improvement 12 weeks after the test treatment. The secondary outcome measures were the proportion of patients showing improvement at 24 weeks and the incidence of adverse events. The null hypothesis was that 33% of patients would show hearing improvement, as was reported for a historical control after hyperbaric oxygen therapy.</p> <p>Results</p> <p>In total, 25 patients received the test treatment at a median of 23 days (range 15-32) after the onset of SSHL, between 2007 and 2009. At 12 weeks after the test treatment, 48% (95% CI 28% to 69%; <it>P </it>= 0.086) of patients showed hearing improvement, and the proportion increased to 56% (95% CI 35% to 76%; <it>P </it>= 0.015) at 24 weeks. No serious adverse events were observed.</p> <p>Conclusions</p> <p>Topical IGF1 application using gelatin hydrogels is well tolerated and may be efficacious for hearing recovery in patients with SSHL that is resistant to systemic glucocorticoids.</p

Isolation of Arabidopsis thaliana mutants sensitive to excess boron

Understandings of molecular mechanisms of boron action in plants remain limited to those known in cell walls. Toxicity mechanisms are largely unknown. In order to obtain the insights into mechanisms of boron toxicity, screening of Arabidopsis thaliana mutants sensitive to excess boron was conducted. The screening strategy was to select plants that grow reasonably well under normal boron condition (0.03 mM boric acid), but not under high boron condition (3 mM boric acid). We used root growth as a selection parameter. About 20,000 ethyl methanesulfonate (EMS) mutagenized M2 seeds of Arabidopsis thaliana (ecotype Col-0) were grown on plates containing high levels of boric acid (3 mM). After 2 weeks, plants showed short-root were transferred to media containing normal levels of boric acid (0.03 mM) and those plants that recovered growth were selected. The phenotypes were reevaluated at M3 generation and reselected plants were crossed with Col-0 for genetic analysis. Finally, we isolated 7 recessive mutants. Most of the mutants showed extremely shorter roots than wild type under boron toxicity, but not under the normal condition, indicating its sensitivity to excess boron

Isolation of Arabidopsis thaliana mutants sensitive to excess boron

Understandings of molecular mechanisms of boron action in plants remain limited to those known in cell walls. Toxicity mechanisms are largely unknown. In order to obtain the insights into mechanisms of boron toxicity, screening of Arabidopsis thaliana mutants sensitive to excess boron was conducted. The screening strategy was to select plants that grow reasonably well under normal boron condition (0.03 mM boric acid), but not under high boron condition (3 mM boric acid). We used root growth as a selection parameter. About 20,000 ethyl methanesulfonate (EMS) mutagenized M2 seeds of Arabidopsis thaliana (ecotype Col-0) were grown on plates containing high levels of boric acid (3 mM). After 2 weeks, plants showed short-root were transferred to media containing normal levels of boric acid (0.03 mM) and those plants that recovered growth were selected. The phenotypes were reevaluated at M3 generation and reselected plants were crossed with Col-0 for genetic analysis. Finally, we isolated 7 recessive mutants. Most of the mutants showed extremely shorter roots than wild type under boron toxicity, but not under the normal condition, indicating its sensitivity to excess boron

Difference in cesium accumulation among rice cultivars grown in the paddy field in Fukushima Prefecture in 2011 and 2012

After the accident of the Fukushima 1 Nuclear Power Plant in March 2011, radioactive cesium was released and paddy fields in a wide area including Fukushima Prefecture were contaminated. To estimate the levels of radioactive Cs accumulation in rice produced in Fukushima, it is crucial to obtain the actual data of Cs accumulation levels in rice plants grown in the actual paddy field in Fukushima City. We herein conducted a two-year survey in 2011 and 2012 of radioactive and non-radioactive Cs accumulation in rice using a number of rice cultivars grown in the paddy field in Fukushima City. Our study demonstrated a substantial variation in Cs accumulation levels among the cultivars of rice