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

Arabidopsis TOBAMOVIRUS MULTIPLICATION (TOM) 2 locus encodes a transmembrane protein that interacts with TOM1

The tom2-1 mutation of Arabidopsis thaliana reduces the efficiency of intracellular multiplication of tobamoviruses. The tom2-1 mutant was derived from fast-neutron-irradiated seeds, and the original mutant line also carries ttm1, a dominant modifier that increases tobamovirus multiplication efficiency in a tobamovirus-strain-specific manner in the tom2-1 genetic background. Here, we show that the tom2-1 mutation involved a deletion of ∼20 kb in the nuclear genome. The deleted region included two genes named TOM2A and TOM2B that were both associated with the tom2-1 phenotype, whereas ttm1 corresponded to the translocation of part of the deleted region that included intact TOM2B but not TOM2A. TOM2A encodes a 280 amino acid putative four-pass transmembrane protein with a C-terminal farnesylation signal, while TOM2B encodes a 122 amino acid basic protein. The split-ubiquitin assay demonstrated an interaction of TOM2A both with itself and with TOM1, an integral membrane protein of A.thaliana presumed to be an essential constituent of tobamovirus replication complex. The data presented here suggest that TOM2A is also an integral part of the tobamovirus replication complex

A Simple Method for Differentiating Complicated Parapneumonic Effusion/Empyema from Parapneumonic Effusion Using the Split Pleura Sign and the Amount of Pleural Effusion on Thoracic CT.

BackgroundPleural separation, the "split pleura" sign, has been reported in patients with empyema. However, the diagnostic yield of the split pleura sign for complicated parapneumonic effusion (CPPE)/empyema and its utility for differentiating CPPE/empyema from parapneumonic effusion (PPE) remains unclear. This differentiation is important because CPPE/empyema patients need thoracic drainage. In this regard, the aim of this study was to develop a simple method to distinguish CPPE/empyema from PPE using computed tomography (CT) focusing on the split pleura sign, fluid attenuation values (HU: Hounsfield units), and amount of fluid collection measured on thoracic CT prior to diagnostic thoracentesis.MethodsA total of 83 consecutive patients who underwent chest CT and were diagnosed with CPPE (n=18)/empyema (n=18) or PPE (n=47) based on the diagnostic thoracentesis were retrospectively analyzed.ResultsOn univariate analysis, the split pleura sign (odds ratio (OR), 12.1; p<0.001), total amount of pleural effusion (≥30 mm) (OR, 6.13; p<0.001), HU value≥10 (OR, 5.94; p=0.001), and the presence of septum (OR, 6.43; p=0.018), atelectasis (OR, 6.83; p=0.002), or air (OR, 9.90; p=0.002) in pleural fluid were significantly higher in the CPPE/empyema group than in the PPE group. On multivariate analysis, only the split pleura sign (hazard ratio (HR), 6.70; 95% confidence interval (CI), 1.91-23.5; p=0.003) and total amount of pleural effusion (≥30 mm) on thoracic CT (HR, 7.48; 95%CI, 1.76-31.8; p=0.006) were risk factors for empyema. Sensitivity, specificity, positive predictive value, and negative predictive value of the presence of both split pleura sign and total amount of pleural effusion (≥30 mm) on thoracic CT for CPPE/empyema were 79.4%, 80.9%, 75%, and 84.4%, respectively, with an area under the curve of 0.801 on receiver operating characteristic curve analysis.ConclusionThis study showed a high diagnostic yield of the split pleura sign and total amount of pleural fluid (≥30 mm) on thoracic CT that is useful and simple for discriminating between CPPE/empyema and PPE prior to diagnostic thoracentesis

A Simple Method for Differentiating Complicated Parapneumonic Effusion/Empyema from Parapneumonic Effusion Using the Split Pleura Sign and the Amount of Pleural Effusion on Thoracic CT.

BackgroundPleural separation, the "split pleura" sign, has been reported in patients with empyema. However, the diagnostic yield of the split pleura sign for complicated parapneumonic effusion (CPPE)/empyema and its utility for differentiating CPPE/empyema from parapneumonic effusion (PPE) remains unclear. This differentiation is important because CPPE/empyema patients need thoracic drainage. In this regard, the aim of this study was to develop a simple method to distinguish CPPE/empyema from PPE using computed tomography (CT) focusing on the split pleura sign, fluid attenuation values (HU: Hounsfield units), and amount of fluid collection measured on thoracic CT prior to diagnostic thoracentesis.MethodsA total of 83 consecutive patients who underwent chest CT and were diagnosed with CPPE (n=18)/empyema (n=18) or PPE (n=47) based on the diagnostic thoracentesis were retrospectively analyzed.ResultsOn univariate analysis, the split pleura sign (odds ratio (OR), 12.1; p<0.001), total amount of pleural effusion (≥30 mm) (OR, 6.13; p<0.001), HU value≥10 (OR, 5.94; p=0.001), and the presence of septum (OR, 6.43; p=0.018), atelectasis (OR, 6.83; p=0.002), or air (OR, 9.90; p=0.002) in pleural fluid were significantly higher in the CPPE/empyema group than in the PPE group. On multivariate analysis, only the split pleura sign (hazard ratio (HR), 6.70; 95% confidence interval (CI), 1.91-23.5; p=0.003) and total amount of pleural effusion (≥30 mm) on thoracic CT (HR, 7.48; 95%CI, 1.76-31.8; p=0.006) were risk factors for empyema. Sensitivity, specificity, positive predictive value, and negative predictive value of the presence of both split pleura sign and total amount of pleural effusion (≥30 mm) on thoracic CT for CPPE/empyema were 79.4%, 80.9%, 75%, and 84.4%, respectively, with an area under the curve of 0.801 on receiver operating characteristic curve analysis.ConclusionThis study showed a high diagnostic yield of the split pleura sign and total amount of pleural fluid (≥30 mm) on thoracic CT that is useful and simple for discriminating between CPPE/empyema and PPE prior to diagnostic thoracentesis

Correlations among radiological parameters in both PPE (A-C) and CPPE/empyema groups (D-F).

<p>A significant correlation between total amount of fluid and thickness of the visceral pleura is seen in both CPPE/empyema (r = 0.394, <i>p</i> = 0.019) and PPE groups (r = 0.318, <i>p</i> = 0.03). Similarly, the thickness of visceral pleura and HU (Hounsfield units) value show moderate positive correlations in both groups (CPPE/empyema group: r = 0.454, <i>p</i> = 0.006; PPE group: r = 0.438, <i>p</i> = 0.002). A significant correlation between total amount of pleural fluid and HU value is seen in the PPE group, but not in the CPPE/empyema group.</p

Measurement of total amount of pleural effusion.

<p>The amount of pleural effusion is calculated from the distance between the parietal and visceral pleura layers by drawing a vertical line (Fig 1).</p

Diagnostic accuracies of the two risk factors for CPPE/empyema.

<p>AUC: area uncer the curve, CPPE: complicated parapneumonic effusion, PE: pleural effusion</p><p>Diagnostic accuracies of the two risk factors for CPPE/empyema.</p

Correlation between serum WBC counts and pleural fluid TCC in the CPPE/empyema and PPE groups.

<p>No apparent associations are seen between serum WBC counts and pleural fluid TCC in the CPPE/empyema group (r = -0.134, <i>p</i> = 0.444) and PPE group (r = -0.172, <i>p</i> = 0.382). CPPE: complicated parapneumonic effusion, PPE: parapneumonic effusion, TCC: total cell count, WBC: white blood cell count.</p

Representative figures for hemi-split pleura sign (A, B) and split pleura sign (C, D).

<p>Thickened visceral or parietal pleura on thoracic CT show the “hemi-split pleura sign” (A, B). When both pleura are thickened and separated by effusion, this is defined as the “split pleura sign” (C, D).</p