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.

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.

Disruption of colonic barrier function and induction of mediator release by strains of Campylobacter jejuni that invade epithelial cells

AIM: To study the mechanisms by which Campylobacter jejuni (C. jejuni) causes inflammation and diarrhea. In particular, direct interactions with intestinal epithelial cells and effects on barrier function are poorly under- stood. METHODS: To model the initial pathogenic effects of C. jejuni on intestinal epithelium, polarized human colonic HCA-7 monolayers were grown on permeabilized filters and infected apically with clinical isolates of C. jejuni. Integrity of the monolayer was monitored by changes in monolayer resistance, release of lactate dehydrogenase, mannitol fluxes and electron microscopy. Invasion of HCA-7 cells was assessed by a modified gentamicin protection assay, translocation by counting colony forming units in the basal chamber, stimulation of mediator release by immunoassays and secretory responses in monolayers stimulated by bradykinin in an Ussing chamber. RESULTS: All strains translocated across monolayers but only a minority invaded HCA-7 cells. Strains that invaded HCA-7 cells destroyed monolayer resistance over 6 h, accompanied by increased release of lactate dehydrogenase, a four-fold increase in permeability to [3H] mannitol, and ultrastructural disruption of tight junctions, with rounding and lifting of cells off the filter membrane. Synthesis of interleukin (IL)-8 and prostaglandin E2 was increased with strains that invaded the monolayer but not with those that did not. CONCLUSION: These data demonstrate two distinct effects of C. jejuni on colonic epithelial cells and provide an informative model for further investigation of initial host cell responses to C. jejuni.

Pure metal extraction from molten oxide slag by short-circuit galvanic cell

The oxygen-ion-permeable membrane galvanic short-circuit method has been developed, in which pure metal was directly extracted from the molten oxide slag, and no external voltage is applied. The galvanic cell employed in the experiment was as follows: graphite rod|[O]Fe+C saturation|ZrO2(MgO)|(FeO)(slag)|Fe rod. The reduction current in the galvanic cell consisted of an external short-circuit current and an interior short-circuit current in the oxygen-ion-permeable membrane. The real-time variation of external circuit reduction ratio of the molten slag could be obtained from the curve of the external circuit current to the time.

Pure metal extraction from molten oxide slag by short-circuit galvanic cell

The oxygen-ion-permeable membrane galvanic short-circuit method has been developed, in which pure metal was directly extracted from the molten oxide slag, and no external voltage is applied. The galvanic cell employed in the experiment was as follows: graphite rod|[O]_(Fe+C saturation)[ZrO_2(MgO)|(FeO)_(slag))|Fe rod. The reduction current in the galvanic cell consisted of an external short-circuit current and an interior short-circuit current in the oxygen-ion-permeable membrane. The real-time variation of external circuit reduction ratio of the molten slag could be obtained from the curve of the external circuit current to the time.

Actin Dynamics Regulates Voltage-Dependent Calcium-Permeable Channels of the Vicia faba Guard Cell Plasma Membrane

Free cytosolic Ca^2＋ （[Ca^2＋]cyt） is an ubiquitous second messenger in plant cell signaling, and [Ca^2＋]cyt elevation is associated with Ca^2＋-permeable channels in the plasma membrane and endomembranes regulated by a wide range of stimuli. However, knowledge regarding Ca^2＋ channels and their regulation remains limited in planta. A type of voltage- dependent Ca^2＋-permeable channel was identified and characterized for the Vicia faba L. guard cell plasma membrane by using patch-clamp techniques. These channels are permeable to both Ba^2＋ and Ca^2＋, and their activities can be inhibited by micromolar Gd^3＋. The unitary conductance and the reversal potential of the channels depend on the Ca^2＋ or Ba^2＋ gradients across the plasma membrane. The inward whole-cell Ca^2＋ （Ba^2＋） current, as well as the unitary current amplitude and NPo of the single Ca^2＋ channel, increase along with the membrane hyperpolarization. Pharmacological experiments suggest that actin dynamics may serve as an upstream regulator of this type of calcium channel of the guard cell plasma membrane. Cytochalasin D, an actin polymerization blocker, activated the NPo of these channels at the single channel level and increased the current amplitude at the whole-cell level. But these channel activations and current increments could be restrained by pretreatment with an F-actin stabilizer, phalloidin. The potential physiological significance of this regulatory mechanism is also discussed.

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.

Pigment epithelium-derived factor protects retinal ganglion cells from hypoxia-induced apoptosis by preventing mitochondrial dysfunction

AIM： To investigate the potential of pigment epitheliumderived factor（PEDF） to protect the immortalized rat retinal ganglion cells-5（RGC-5） exposed to Co Cl2-induced chemical hypoxia. METHODS： After being differentiated with staurosporine（SS）, RGC-5 cells were cultured in four conditions： control group cells cultured in Dulbecco ＇s modified eagle medium（DMEM） supplemented with 10% fetal bovine serum, 100 μmol/m L streptomycin and penicillin（named as normal conditions）; hypoxia group cells cultured in DMEM containing 300 μmol/m L Co Cl2; cells in the group protected by PEDF were first pretreated with 100 ng/m L PEDF for 2h and then cultured in the same condition as hypoxia group cells; and PEDF group cells that were cultured in the presence of 100 ng/m L PEDF under normal conditions. The cell viability was assessed by MTT assay, the percentage of apoptotic cells was quantified using Annexin V-FITC apoptosis kit, and intra-cellar reactive oxygen species（ROS） was measured by dichloro-dihydro-fluorescein diacetate（DCFH-DA） probe. The mitochondria-mediated apoptosis was also examined to further study the underlying mechanism of the protective effect of PEDF. The opening of mitochondrial permeability transition pores（m PTPs） and membrane potential（Δψm） were tested as cellular adenosine triphosphate（ATP） level and glutathione（GSH）. Also, the expression and distribution of Cyt C and apoptosis inducing factor（AIF） were observed.RESULTS： SS induced differentiation of RGC-5 cells resulting in elongation of their neurites and establishing contacts between outgrowths. Exposure to 300 μmol/m L Co Cl2 triggered death of 30% of the total cells in cultures within 24 h. At the same time, pretreatment with 100 ng/m L PEDF significantly suppressed the cell death induced by hypoxia（P〈0.05）. The apoptosis induced by treatment of Co Cl2 was that induced cell death accompanied with increasing intracellar ROS and decreasing GSH and ATP level. PEDF pretreatment suppressed these effects（P〈0.05）. Additionally, PEDF treatment inhibited the opening of m PTPs and suppressed decreasing of Δψm in RGC-5 cells, resulting in blocking of the mitochondrial apoptotic pathway.CONCLUSION： Pretreatment of RGC-5 cells with 100 ng/m L PEDF significantly decreases the extent of apoptosis. PEDF inhibits the opening of m PTPs and suppresses decreasing of Δψm. Moreover, PEDF also reduces ROS production and inhibits cellular ATP level＇s reduction. Cyt C and AIF activation in PEDF-pretreated cultures are also reduced. These results demonstrate the potential for PEDF to protect RGCs against hypoxic damage in vitro by preventing mitochondrial dysfunction.

利用Triton X-100提升巴氏芽孢杆菌脲酶活性的效果

微生物诱导碳酸盐沉积(MICP)技术是近年来发展起来的一种新型绿色加固技术,如何提升MICP技术的加固效能一直是学者关注的热点,本工作重点结合巴氏芽孢杆菌产脲酶原理和非离子表面活性剂的特点,设计采用非离子表面活性剂Triton X-100提升MICP效能的试验研究。结果表明:(1)在单因素试验结果的基础上,通过响应面试验分析确定了活性剂的最优处理条件,即掺量1.37%、处理时间5.02 h、处理温度34.28℃、菌胶比1∶2.11;(2)采用最优条件处理的巴氏芽孢杆菌对钙质砂进行加固后,钙质砂固化体碳酸钙含量和无侧限抗压强度分别提升了25.48%和22.83%;(3)非离子表面活性剂Triton X-100增大了巴氏芽孢杆菌的细胞膜通透性,一方面使得更多的胞内脲酶释放到细胞外,同时更多的尿素分子进入到细胞内,促进了尿素水解,提升了碳酸钙的生成速率;另一方面使得以细菌为核点生成的碳酸钙胶凝体的结构更为致密,在这两方面作用下,MICP效能得到有效提升。相关思路和研究结果可为MICP加固效果的提升提供新的参考和思路。

源自蜡样芽孢杆菌抗菌肽DB16的筛选及其对金黄色葡萄球菌的抑菌机制

本实验发现当与蜡样芽孢杆菌混合培养时,金黄色葡萄球菌的生长受到抑制。结合生物信息学方法从蜡样芽孢杆菌DeadBoxATP依赖性RNA解旋酶中预测、筛选得到抗菌肽DB16(RKLLQFAKKLGIVFTK)。抗菌肽DB16对金黄色葡萄球菌的最低抑菌质量浓度(minimum inhibitory concentration,MIC)为31.25μg/mL,可在0.5 h内完全抑制金黄色葡萄球菌的生长;抗菌肽DB16在磷酸盐缓冲溶液中呈现无规卷曲结构,在十二烷基硫酸钠环境中转变为α-螺旋结构。采用荧光探针、流式细胞术、透射电子显微镜、DNA凝胶电泳以及圆二色谱等方法探究抗菌肽DB16对金黄色葡萄球菌的抑菌机制,结果表明,抗菌肽DB16能够改变细菌细胞膜通透性,造成细胞内容物外泄,同时进入胞内与金黄色葡萄球菌基因组DNA结合,影响正常DNA的复制,最终抑制菌体的生长繁殖。此外,对哺乳动物红细胞的处理表明,DB16在8×MIC条件下仍无溶血性。综上,源自蜡样芽孢杆菌的抗菌肽DB16在金黄色葡萄球菌防控方面具有很大应用潜力。

3种超声方式对蓝莓蜡质层和细胞结构及真空冷冻干燥特性的影响

蓝莓表皮蜡质成分严重阻碍其真空冷冻干燥过程中的水分扩散。以新鲜蓝莓为原料,分析3种超声方式对蓝莓蜡质层和内部细胞结构的影响,结合蓝莓脆品质特性和干燥特性,探究适宜蓝莓真空冷冻干燥的超声预处理方式。气相色谱-质谱联用结果表明:不同超声处理对蓝莓表皮蜡质组成和含量影响不同,其中间歇式超声处理后蓝莓表皮蜡质组成和总相对含量变化最大,与对照组相比总相对含量减少了35%。微观结构分析结果表明:探头式和间歇式超声处理后蓝莓表皮的蜡质分布疏松,表皮裸露;连续式超声处理后蓝莓表皮蜡质晶体结构由管状变为片状。探头式和间歇式超声处理对蓝莓内部细胞结构破坏较大,使其形成大尺寸微通道,并且探头式超声处理后,蓝莓细胞膜渗透率显著高于其他处理方式(P<0.05)。不同超声处理后蓝莓的T 2弛豫曲线均整体向左移动,峰面积和信号幅值减小;3种超声处理方式明显改善了真空冷冻干燥蓝莓干燥速率,连续式和探头式超声处理显著改善了真空冷冻干燥蓝莓的脆性,分别提高了38.25%、40.09%。连续式超声处理获得的真空冷冻干燥蓝莓维生素C和花青素保留率显著提高,分别为86.17%±0.18%和71.30%±1.88%。综合比较,连续式超声处理是较优的蓝莓真空冷冻干燥预处理方式。

7种中药提取物体外抑制金黄色葡萄球菌的效果及机制研究

本研究旨在探究黄芩苷、小檗碱、杜鹃花、虎儿草、唐古特青蓝、诃子、沙棘果7种中药对金黄色葡萄球菌的体外抑菌效果以及其作用机制。通过微量肉汤稀释法测定7种不同中药材水或醇提取物对金黄色葡萄球菌的最小抑菌浓度,并测定不同药物提取物浓度下金黄色葡萄球菌的生长曲线,研究中药对金黄色葡萄球菌的体外抑菌效果;然后测定中药材对金黄色葡萄球菌生物被膜生成的影响、生物被膜通透性的影响和胞内三磷酸腺苷(ATP)含量的影响来研究其抑菌机制。结果表明,所有中草药提取物对金黄色葡萄球菌均有抑制作用,其中小檗碱和黄芩苷2种中药抑菌作用优于其他中药提取物。中药处理组的金黄色葡萄球菌生长缓慢,小檗碱对金黄色葡萄球菌的生长抑制作用最强。小檗碱、黄芩苷、唐古特青蓝、杜鹃花、沙棘果、虎儿草水提取物以及唐古特青蓝、杜鹃花、诃子、沙棘果、虎儿草的醇提取物能明显抑制金黄色葡萄球菌生物膜的形成。经过黄芩苷和小檗碱处理后,金黄色葡萄球菌胞外总蛋白和核酸含量与药物提取物浓度呈正相关增加。经过小檗碱作用后的金黄色葡萄球菌胞内的ATP含量显著下降。综上,7种中药对金黄色葡萄球菌有体外抑菌效果,能够抑制细菌的生长,其机制与影响金黄色葡萄球菌的生物被膜通透性以及细胞能量代谢相关。

汞污染水体下AM真菌对水生美人蕉生长、光合生理及汞吸收的影响

为探究汞污染水体下接种AM真菌促进水生美人蕉生长、光合生理及汞吸收的作用,试验模拟水体汞浓度(0、5、10、20 mg/L)并接种AM真菌摩西斗管囊霉(Funneliformis mosseae,FM)、幼套近明球囊霉(Claroideoglomus etunicatum,CE)、共同双接种(FM+CE)以及不接种对照(CK)共16个处理,测定水生美人蕉生长、光合作用、渗透调节以及植物体内汞含量等指标。结果表明,水环境中AM真菌与水生美人蕉能形成稳定共生关系,菌根侵染率和菌丝密度最高达63.0%和1.68 m/g,低浓度汞对AM真菌侵染无影响,而高浓度下则降低AM真菌侵染率和菌丝密度。随汞浓度增加,接种AM真菌能够促进水生美人蕉对地上部和根系的汞吸收量,增强根系对汞的富集能力而降低转移系数。在汞5 mg/L浓度水平下,与CK相比,FM+CE处理的水生美人蕉叶片叶绿素a含量差异不显著,叶绿素b含量提高47.4%;FM+CE处理的净光合速率、蒸腾速率和胞间CO_(2)浓度比CK处理分别增加12.2%、28.6%和6.3%,地上部氮含量增加38.8%,根系磷吸收量增加85.7%,渗透调节物质中可溶性糖和脯氨酸含量分别增加67.6和57.4个百分点,而丙二醛含量和相对电导率分别下降38.9和27.5个百分点。水环境中汞浓度与水生美人蕉地上部和根系汞含量呈正相关关系,与CK处理相比,FM+CE处理的富集系数增加62.5%,而转运系数差异不显著。结论认为接种AM真菌能够显著提高水生美人蕉株高和生物量,增加叶绿素含量并提高光合作用,提高植物对氮、磷的吸收量以及渗透调节物质含量、降低丙二醛和相对电导率来增强对汞污染的抗性,同时能够加强植物根系吸附固持汞,从而减少汞向植株地上部分的转移,相对于单一接种FM、CE处理,共同接种FM+CE处理修复汞污染水体、促进植物生长的效果最好。

肉桂、百里香、罗勒精油联合抑菌活性研究

目的:为探究肉桂、百里香及罗勒精油对致病菌的抑菌作用。方法:选取5种常见致病菌为受试菌,采用棋盘稀释法、抑菌圈等方法选出具有协同抑菌的复配精油,借助气相色谱-质谱联用仪分析3种精油的特征组分。研究大肠杆菌、副溶血性弧菌和金黄色葡萄球菌细胞膜通透性。结果:GC-MS分析表明肉桂醛、百里酚和丁香酚分别为肉桂精油、百里香精油和罗勒精油中的主要抑菌成分。肉桂和百里香精油复配对大肠杆菌和副溶血性弧菌的FIC为0.5,肉桂与罗勒精油复配对大肠杆菌和金黄色葡萄球菌的FIC为0.5。肉桂醛-百里酚复配处理大肠杆菌和副溶血性弧菌的OD_(280nm)比单一组分处理的OD_(280nm)分别提升了6.13%,4.42%,比单一百里酚分别提升了12.44%,12.53%。同样,肉桂醛-丁香酚复配处理大肠杆菌和金黄色葡萄球菌的OD_(280nm)比单一肉桂醛分别提升了8.97%,7.38%,比单一丁香酚分别提升了17.02%,24.69%。结论:肉桂和百里香精油复配对大肠杆菌和副溶血性弧菌具有协同抑菌作用,肉桂-百里香精油和肉桂-罗勒精油的协同抑菌分别是肉桂醛-百里酚和肉桂醛-丁香酚的联合作用所致,且复配组分通过破坏菌体的细胞膜完整性,使其通透性增加,核酸、蛋白质等胞内容物大量泄露,导致菌体死亡。

马铃薯疮痂病菌Streptomyces acidiscabies鉴定及抑菌有机酸筛选

本研究旨在鉴定微型薯连作基质中疮痂病原菌的种类,筛选具有良好抑制活性的有机酸以利于控制疮痂病发生。研究从病薯上分离纯化病原菌,用薯片法、萝卜片法及温室盆栽接种法检测其致病性,结合形态学观察、生理生化特性测定及16S rRNA基因序列分析确定种类,对其耐盐性等生物学特性进行研究,用纸碟法测定甲酸等有机酸对疮痂链霉菌生长的影响。链霉菌19311具有致病性,其致病岛毒力相关基因型为txtAB+/tomA+/necI+,根据19311菌株培养特征、生理生化特性及16S rRNA序列分析结果鉴定为酸性疮痂链霉菌(Streptomyces acidiscabies)。甲酸、乙酸、丙酸、乳酸、柠檬酸、酒石酸可显著抑制S.acidiscabies的生长,甲酸抑菌效果最佳,抑菌圈直径为45.43 mm,抑菌最低有效浓度为1%,可通过增加细胞膜通透性抑制S.acidiscabies生长。综上所述,本研究明确了微型薯生产基质中疮痂链霉菌19311的种类及其生物学特性。未来可考虑使用1%甲酸进行疮痂病的控制试验,并评估其对原原种生产的潜在影响。

Membrane nanotubes:Novel communication between distant cells

The many kinds of cell structures involved in cell-cell communication include tight junction,adherens junction and gap junction,but almost all are between adjacent cells.Recently,a general and dynamic membrane tether,termed tunneling nanotubes or membrane nanotubes(MNTs),was discovered to be involved in communication between distant cells.By facilitating intercellular communication,MNTs contribute to many biological functions and pathologic changes in cells.Many works have revealed the structure,formation and functional properties of MNTs.However,as novel structures,further research is needed.

Effect of Sulfonation Degree on Performance of Proton Exchange Membranes for Direct Methanol Fuel Cells

A series of proton exchange membranes based on sulfonated polyarylene ether ketones（SPAEKs） was used to study the effect of sulfonation degree on proton conductivity, methanol permeation and performance of direct methanol fuel cells（DMFCs）. Dependences of physical characteristics of the membranes, i. e., proton conductivity, water uptake, swelling ratio, methanol permeability and ion exchange capacity（IEC） were systematically studied. Both methanol permeability and proton conductivity of the SPAEK membrane grow rapidly as the increase in sulfonation degree since methanol molecules and protons share the same transfer channel. However, the methanol permeability plays more important role comparing to proton conductivity. As a result, the SPAEK membrane with a medium sulfonation degree（60%） was found to yield the best performance in a DMFC due to the acquirement of balanced conductivity and methanol permeability.

超声对细胞膜通透性的影响及应用

适当参数的超声，使细胞膜发生可以修复的损伤，使细胞膜的通透性提高，从而使细胞内的物质释放到细胞外，细胞外的物质进入细胞内。这一现象可以用于释放代谢产物或中间产物，基因转导，强化化学方法治疗肿瘤等方面。

棕榈在北方不同生态环境下越冬栽培适应性的生理研究

在设置的不同生态环境小区内栽培棕榈 ,通过分析越冬栽培期间不同小区内的温度、风速及空气相对湿度等气候因子 ,观察植株寒害反应及来年生长状况 ,并结合植株叶片组织水分、可溶性糖及可溶性蛋白的质量分数和过氧化物酶 (POD)及超氧歧化酶 (SOD)比活性的测定 ,揭示了棕榈北方越冬栽培适应性的生理基础和伤害发生的可能机制 .结果表明 ,背风向阳的生态环境、一定程度的低温、大风 ,引发叶片组织中水的质量分数降低、渗透调节物质可溶性糖和可溶性蛋白等的质量分数以及膜的保护酶POD和SOD的比活性提高 ,这有利于植株抵御寒害 ,安全越冬 .自然裸地生态环境内的低温 ,尤其是大的风速加之较低的空气相对湿度 ,使叶片组织的POD和SOD比活性下降、质膜透性增强 ,叶片呈现生理干旱的伤害性特征 ,且部分植株生长点部位严重受害 ,翌年死亡 .冬季寒潮所造成的极端低温以及大风引发的生理干旱 ,是棕榈树在北方户外越冬的限制因子 .