Burkholderia insecticola sp. nov., a gut symbiotic bacterium of the bean bug Riptortus pedestris

A Gram-negative, aerobic, rod-shaped, non-spore-forming, motile bacterium, designated strain RPE64(T), was isolated from the gut symbiotic organ of the bean bug Riptortus pedestris, collected in Tsukuba, Japan, in 2007. 16S rRNA gene sequencing showed that this strain belongs to the Burkholderia glathei Glade, exhibiting the highest sequence similarity to Burkholderia peredens LMG 29314(T) (100%), Burkholderia turbans LMG 29316(T) (99.52%) and Burkholderia ptereochthonis LMG 29326(T) (99.04 %). Phylogenomic analyses based on 107 single-copy core genes and Genome BLAST Distance Phylogeny confirmed B. peredens LMG 29314(T), B. ptereochthonis LMG 29326(T) and several uncultivated, endophytic Burkholderia species as its nearest phylogenetic neighbours. Digital DNA-DNA hybridization experiments unambiguously demonstrated that strain RPE64(T) represents a novel species in this lineage. The G+C content of its genome was 63.2 mol%. The isoprenoid quinone was ubiquinone 8 and the predominant fatty acid components were C-16:0, C-18:1 omega 7c and C-17:0 cyclo. The absence of nitrate reduction and the capacity to grow at pH 8 clearly differentiated strain RPE64(T) from related Burkholderia species. Based on these genotypic and phenotypic characteristics, strain RPE64(T) is classified as representing a novel species of the genus Burkholderia, for which the name Burkholderia insecticola sp. nov. is proposed. The type strain is RPE64(T) (=NCIMB 15023(T)=JCM 31142(T))

Zinc increases vulnerability of rat thymic lymphocytes to arachidonic acid under in vitro conditions

Previous studies on the cytotoxicity of arachidonic acid (ARA) elucidated the involvement of oxidative stress and Ca2+. In the present study, the Zn2+-related cytotoxicity of ARA was studied by a flow cytometric technique with appropriate fluorescent probes in rat thymocytes. Addition of 10 μM ZnCl2 enhanced the increase in cell lethality induced by 10 μM ARA. The removal of Zn2+ by Zn2+ chelators attenuated the ARA-induced increase in cell lethality. Thus, Zn2+ is suggested to be involved in ARA cytotoxicity. ARA at 3–10 μM elevated intracellular Zn2+ level. The Zn2+ chelators attenuated the ARA-induced increase in intracellular Zn2+ level while ARA significantly increased intracellular Zn2+ level in the presence of 3 μM ZnCl2, suggesting the involvement of external Zn2+. Zn2+ reportedly exerts cytotoxic action under oxidative stress induced by hydrogen peroxide, via an excessive increase in intracellular Zn2+ levels. Since ARA induces oxidative stress, the simultaneous administration of zinc and ARA may be harmful

Zinc-related actions of sublethal levels of benzalkonium chloride : Potentiation of benzalkonium cytotoxicity by zinc

Benzalkonium chloride (BZK) is a common preservative used in pharmaceutical and personal care products. ZnCl2 was recently reported to significantly potentiate the cytotoxicity of some biocidal compounds. In the present study, therefore, we compared the cytotoxic potency of BZK and then further studied the Zn2+-related actions of the most cytotoxic agent among BZK, using flow cytometric techniques with appropriate fluorescent probes in rat thymocytes. Cytotoxicity of benzylcetyldimethylammonium (BZK-C16) was more potent that those of benzyldodecyldimethylammonium and benzyldimethyltetradecylammonium. ZnCl2 (1–10 μM) significantly potentiated the cytotoxicity of BZK-C16 at a sublethal concentration (1 μM). The co-treatment of cells with 3 μM ZnCl2 and 1 μM BZK-C16 increased the population of both living cells with phosphatidylserine exposed on membrane surfaces and dead cells. BZK-C16 at 0.3–1.0 μM elevated intracellular Zn2+ levels by increasing Zn2+ influx, and augmented the cytotoxicity of 100 μM H2O2. Zn2+ is concluded to facilitate the toxicity of BZK. We suggest that the toxicity of BZK is determined after taking extracellular (plasma) and/or environmental Zn2+ levels into account

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements