Effects of exogenous Ca^(2+) on the membrane permeability, MDA and SH group content of Alexandrium sp. LC3 under surfactant stress

The effect of Ca 2+ on the removal of Alexandrium sp. LC3 under HDTMAB stress was investigated. The results showed that the toxic effect of HDTMAB on Alexandrium sp. LC3 was significantly reduced in the presence of Ca 2+, especially under 4 mmol/L of Ca 2+. To understand the underlying mechanism, the SH group and MDA content of the cell membrane and membrane permeability were measured. It was found that the SH content of cell member increased, the MDA content and membrane permeability decreased when Alexandrium sp. was treated with Ca 2+ and HDTMAB complex, compared with using HDTMAB only. The data suggested that Ca 2+ might promote HDTMAB stress resistance of Alexandrium sp. LC3 by reducing the permeability and increasing the stability of cell membrane.

Non-Thermal Biological Effect of Graphene Far-Infrared Ray on Saccharomyces cerevisiae Cells

Graphene materials can emit far-infrared ray, but the biological effects of graphene far-infrared ray have not been studied. Furthermore, the non-thermal biological effect of far-infrared ray on organism has not been systematically studied independently of the thermal effect. The purpose of this study was to investigate the non-thermal biological effect of graphene far-infrared ray (gFIR) on Saccharomyces cerevisiae cells. In this work, stringent control of the cultivation conditions was carried out to ensure the stability and constancy of the culture and its temperature. Flow cytometry was used to detect the non-thermal effect of gFIR irradiation on cell membrane permeability, mitochondrial membrane potential (MMP) and intracellular reactive oxygen species (ROS) content. Compared with the control group, cell membrane permeability of the gFIR exposure cells decreased by 4.7%, MMP increased by 16% and intracellular ROS reduced by 10.7%. The results revealed the valuable features of the non-thermal biological effect of gFIR on Saccharomyces cerevisiae cells, and the further analysis demonstrated that graphene far-infrared materials should have great application value in disease prevention and health promotion.

Promotion of hexadecyltrimethyleamine bromide to the damage of Alexandrium sp.LC3 by cupric glutamate

The effect of hexadecyltrimethyleamine bromide （HDTMAB） on the removal of A lexandrium sp. LC3 under cupric glutamate stress was investigated. Toxic effect of cupric glutamate on A lexandrium sp. LC3 was significantly promoted in the presence of HDTMAB, especially at 3.0 cmc of HDTMAB. It was found that the sulfhydryl group content of the cell decreased, while the malonaldehyde content and membrane permeability increased when A lexandrium sp. LC3 was treated with HDTMAB and cupric glutamate complex, compared with cupric glutamate alone. The data suggest that HDTMAB might stimulate the damage of A lexandrium sp. LC3 by enhancing the membrane permeability.

Effect of Drought Stress on Growth and Water Physiological Characteris­tics of Poa sibirica

In order to develop the resources of native turfgrass,the morphological traits and drought resistance of native Siberian bluegrass(Poa sibirica,abbreviated as PS)was evaluated using the introduced Kentucky bluegrass'Midnight'(Poa pratensis,abbreviated as PP)as a control.Two water schemes were imposed to plants in this pot culture study in greenhouse.One was with drought stress persistent limiting water supply for 20 days,the other was re-hydrated until 14 days after drought.The leaf shape,turf color,water status and cell plasma membrane permeability were evaluated.Similar changing trends with these parameters were shown for both species,and there were not significant differences with most evaluations during drought and re-water periods.The values leaf width and length of PS were higher while leaf color intensity was slightly lower than that of PP,but the greenness of PS leaf was still visually acceptable.There were not significant differences with cell membrane stability between the two species.In comparison,the native wild species PS possessed the potential for to be domesticated into a new cultivar for turf industry.

Herbicide promotes the conjugative transfer of multi-resistance genes by facilitating cellular contact and plasmid transfer

The global dissemination of antibiotic resistance genes(ARGs),especially via plasmid-mediated horizontal transfer,is becoming a pervasive health threat.While our previous study found that herbicides can accelerate the horizontal gene transfer(HGT)of ARGs in soil bacteria,the underlying mechanisms by which herbicides promote the HGT of ARGs across and within bacterial genera are still unclear.Here,the underlying mechanism associ-ated with herbicide-promoted HGT was analyzed by detecting intracellular reactive oxygen species(ROS)production,extracellular polymeric substance composition,cell membrane integrity and proton motive force combined with genome-wide RNA sequencing.Exposure to herbicides induced a series of the above bacterial responses to promote HGT except for the ROS response,including compact cell-to-cell contact by enhancing pilus-encoded gene expression and decreasing cell surface charge,increasing cell membrane permeability,and enhancing the proton motive force,providing additional power for DNA uptake.This study provides a mechanistic understanding of the risk of bacterial resistance spread promoted by herbicides,which elucidates a new perspective on nonantibiotic agrochemical acceleration of the HGT of ARGs.