Bacillus cereus, a potential pathogen of snakehead fish Ophiocephalus argus

Bacillus cereus is an emerging pathogen that has caused high mortalities in aquaculture animals. Yet the pathogenicity of B. cereus in snakehead fish Ophiocephalus argus is still unclear. In this study, a virulent strain (CA4) was isolated from diseased snakehead fish suffering from a typical symptom of hepatic hemorrhage with blood vessel congestion and macrophage infiltration, and was identified molecularly and phenotypically as B. cereus. It was β-hemolytic, showed an LD50 value of 2.57×106 CFU mL-1 for snakehead fish, and developed multiple resistances to cotrimoxazole, doxycycline, florfenicol, neomycin, sulfisoxazole, and tetracycline in aquaculture use. To the best of our knowledge, this is the first report of snakehead fish- pathogenic B. cereus. The findings of this study provide new insights into the potential threat of pathogenic B. cereus to snakehead fish

Stochastic back analysis of permeability coefficient using generalized Bayesian method

Owing to the fact that the conventional deterministic back analysis of the permeability coefficient cannot reflect the uncertainties of parameters, including the hydraulic head at the boundary, the permeability coefficient and measured hydraulic head, a stochastic back analysis taking consideration of uncertainties of parameters was performed using the generalized Bayesian method. Based on the stochastic finite element method (SFEM) for a seepage field, the variable metric algorithm and the generalized Bayesian method, formulas for stochastic back analysis of the permeability coefficient were derived. A case study of seepage analysis of a sluice foundation was performed to illustrate the proposed method. The results indicate that, with the generalized Bayesian method that considers the uncertainties of measured hydraulic head, the permeability coefficient and the hydraulic head at the boundary, both the mean and standard deviation of the permeability coefficient can be obtained and the standard deviation is less than that obtained by the conventional Bayesian method. Therefore, the present method is valid and applicable

Two-photon-induced excited state intramolecular proton transfer process and nonlinear optical properties of HBT in cyclohexane solution

The two-photon-induced excited state intramolecular proton transfer (ESIPT) process of 2-(2 ' -hydroxyphenyl) benzothiazole (HBT) in cyclohexane solution has been investigated. We focus on the calculation of the two-photon absorption (TPA) coefficient and nonlinear refraction index of HBT, and the theoretical computational results are in good agreement with the experimental ones. By establishing the ESIPT kinetic model for HBT based on TPA, the TPA cross section is obtained. The numerical results show that HBT exhibits a rather large TPA cross section compared with that of 2-(2 ' -hydroxyphenyl)benzoxazole (HBO) reported previously. Therefore, HBT is a promising TPA material and is worthy of further research

Auxin guides germ-cell specification in Arabidopsis anthers

International audienceSignificance Germ cells (GCs) (i.e., the cells that are committed to meiosis and gametogenesis) are key carriers for eukaryotes to complete their life cycle, transmitting their genetic information from one generation to the next while generating variations to integrate environmental changes. Compared to what has been known in animals, very little is known about how the GCs in plants are segregated from somatic cells. This work demonstrates that auxin is a key factor guiding GC specification in Arabidopsis anthers. Local auxin biosynthesis interacts with the transcription of SPOROCYTELESS/NOZZLE and a progressive GC specification itself to form a dynamic feedback circuit that ensures the completion of GC specification

Association between Promoter Methylation of Gene ERCC3 and Benzene Hematotoxicity

Benzene is a primary industrial chemical and a ubiquitous environmental pollutant. ERCC3 is a key player in nucleotide excision repair. Recent studies suggested that site-specific methylation is a possible mechanism of the transcriptional dysregulation by blocking transcription factors binding. We previously found that the average promoter methylation level of ERCC3 was increased in benzene-exposed workers. In order to test whether specific CpG sites of ERCC3 play an important role in benzene-induced epigenetic changes and whether the specific methylation patterns are associated with benzene hematotoxicity, we analyzed the promoter methylation levels of individual CpG sites, transcription factor binding motif and the correlation between aberrant CpG methylation and hematotoxicity in 76 benzene-exposed workers and 24 unexposed controls in China. Out of all the CpGs analyzed, two CpG units located 43 bp upstream and 99 bp downstream of the transcription start site of ERCC3 (CpG 2–4 and CpG 17–18, respectively), showed the most pronounced increase in methylation levels in benzene-exposed workers, compared with unexposed controls (Mean ± SD: 5.86 ± 2.77% vs. 4.92 ± 1.53%, p = 0.032; 8.45 ± 4.09% vs. 6.79 ± 2.50%, p = 0.024, respectively). Using the JASPAR CORE Database, we found that CpG 2–4 and CpG 17–18 were bound by three putative transcription factors (TFAP2A, E2F4 and MZF1). Furthermore, the methylation levels for CpG 2–4 were correlated negatively with the percentage of neutrophils (β = −0.676, p = 0.005) in benzene-exposed workers. This study demonstrates that CpG-specific DNA methylation in the ERCC3 promoter region may be involved in benzene-induced epigenetic modification and it may contribute to benzene-induced hematotoxicity

Rosiglitazone Prevents Amyloid-β Oligomer-Induced Impairment Of Synapse Formation And Plasticity Via Increasing Dendrite And Spine Mitochondrial Number

Rosiglitazone has been known to attenuate neurodegeneration in Alzheimer\u27s disease (AD), but the underlying mechanisms remain to be fully elucidated. In this study, living-cell image, immunocytochemistry, and electrophysiology were used to examine the effects of soluble amyloid-β protein (Aβ) oligomers and rosiglitazone on the synapse formation, plasticity, and mitochondrial distribution in cultured neurons. Incubation of hippocampal cultures with amyloid-β (Aβ) 42 oligomers (0.5 μM) for 3 h significantly decreased dendritic filopodium and synapse density. Pretreatment with rosiglitazone (0.5-5 μM) for 24 h prevented the Aβ 42 - induced loss of dendritic filopodium and synapse in a dose-dependent manner. However, neither Aβ 42 oligomer nor rosiglitazone has a significant effect on the velocity and length of dendritic filopodia. Electrophysiological recording showed that acute exposure of slices with 0.5 μM Aβ 42 oligomers impaired hippocampal long-term potentiation (LTP). Pre-incubation of hippocampal slices with rosiglitazone significantly attenuated the Aβ 42 -induced LTP deficit, which depended on rosiglitazone concentrations (1-5 μM) and pretreatment period (1-5 h). The beneficial effects of rosiglitazone were abolished by the peroxisome proliferator-activated receptor gamma (PPARγ) specific antagonist, GW9662. Moreover, the mitochondrial numbers in the dendrite and spine were decreased by Aβ 42 oligomers, which can be prevented by rosiglitazone. In conclusion, our data suggested that rosiglitazone prevents Aβ 42 oligomers-induced impairment via increasing mitochondrial numbers in the dendrite and spine, improving synapse formation and plasticity. This process is most likely through the PPARγ-dependent pathway and in concentration and time dependent manners. The study provides novel insights into the mechanisms for the protective effects of rosiglitzone on AD. © 2014 - IOS Press and the authors. All rights reserved