Early stage toxicity of excess copper to photosystem II of Chlorella pyrenoidosa–OJIP chlorophyll a fluorescence analysis

Acute toxicity of excess Cu on the photosynthetic performance of Chlorella pyrenoidosa was examined by using chlorophyll a fluorescence transients and JIP-test after exposure to elevated Cu concentrations for a short time period. High Cu concentration resulted in a significant suppression in photosynthesis and respiration. The absorption flux (ABS/RC) per PSII reaction center increased with increasing Cu concentration, but the electron transport flux (ET₀/RC) decreased. Excess Cu had an insignificant effect on the trapping flux (TR₀/RC). The decline in the efficiency, with which a trapped exciton can move an electron into the electron transport chain further than Q_A−(Ψ₀), the maximal quantum yield of primary photochemistry (?_P0), and the quantum yield of electron transport (?_E0) were also observed. The amount of active PSII reaction centers per excited cross section (RC/CS) was also in consistency with the change of photosynthesis when cells were exposed to excess Cu concentration. JIP-test parameters had a good linear relationship with photosynthetic O₂ evolution. These results suggested that the decrease of photosynthesis in exposure to excess Cu may be a result of the inactivation of PSII reaction centers and the inhibition of electron transport in the acceptor side.     

超声波在低声能密度下处理污泥的实验研究

文章采用超声波在0.014W/mL、0.025W/mL、0.031W/mL、0.035W/mL四个声能密度水平下,作用时间在0～60min范围内对生活污水厂污泥进行处理。研究结果表明:在低声能密度下,超声波处理污泥45min可以使可溶性化学需氧量(SCOD)溶出率超过10%,同时可以使污泥中氨氮的含量降到5mg/L左右。     

红霉素废液生产单细胞蛋白的发酵条件研究

采用单因素及正交方法,以微生物含量为主要检测指标,研究红霉素废液生产单细胞蛋白的工艺条件。探讨了接菌量、发酵培养基中废液含量、发酵时间、发酵pH值、氮源等因素对单细胞蛋白产量的影响。结果表明,红霉素废液发酵生产蛋白的适宜条件为:发酵培养基中废液含量20%,接菌量6%,pH=6,发酵时间72h。     

Using the nematode Caenorhabditis elegans as a model animal for assessing the toxicity induced by microcystin-LR

Among more than 75 variants of microcystin(MC),microcystin-LR(MC-LR) is one of the most common toxins.In this study,the feasibility of using Caenorhabditis elegans to evaluate MC-LR toxicity was studied.C.elegans was treated with MC-LR at different concentrations ranging from 0.1 to 80 μg/L.The results showed that MC-LR could reduce lifespan,delay development,lengthen generation time,decrease brood size,suppress locomotion behavior,and decreases hsp-16-2-gfp expression.The endpoints of generation time,brood...     

Identification and characterization of the chromium（Ⅵ） responding protein from a newly isolated Ochrobactrum anthropi CTS-325

A Gram-negative, chromium(VI) tolerant and reductive strain CTS-325, isolated from a Chinese chromate plant, was identified as Ochrobactrum anthropi based on its biochemical properties and 16S rDNA sequence analysis. It was able to tolerate up to 10 mmol/L Cr(VI) and completely reduce 1 mmol/L Cr(VI) to Cr(III) within 48 h. When the strain CTS-325 was induced with Cr(VI), a protein increased significantly in the whole cell proteins. Liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis revealed that this protein was a superoxide dismutase (SOD) homology. The measured superoxide dismutase activity was 2694 U/mg after three steps of purification. The SOD catalyzes the dismutation of the superoxide anion (O₂^·−) into hydrogen peroxide and molecular oxygen. This protein is considered to be one of the most important anti-oxidative enzymes for O. anthropi as it allows the bacterium to survive high oxygen stress environments, such as the environment produced during the reduction process of Cr(VI).     

土霉素对小麦种子发芽与幼苗生长发育的生态毒性

研究了土霉素对小麦种子发芽以及早期幼苗生长发育的生态毒性效应.结果表明,土霉素对小麦种子芽长及根长的抑制效应显著(p<0.01),而且它们之间具有良好的剂量-效应关系.根据线性回归方程得出土霉素对小麦种子芽长和根长的半抑制浓度为65.5 mg/L和34.7 mg/L.然而,土霉素对小麦种子的发芽率并没有显著的影响.研究还表明,0.15~2.4 mg/L土霉素暴露21 d后,小麦叶片中的叶绿素含量降低了35.6%~47.3%,叶片及根部的可溶性蛋白含量也均呈显著下降趋势.暴露7 d后,0.15~2.4 mg/L土霉素对小麦叶片和根部SOD与POD活性的抑制效应不显著,但随着暴露时间的延长,土霉素对小麦的SOD与POD酶活性抑制率显著下降;2.4 mg/L土霉素暴露21 d后,小麦根部的SOD活性下降72.3%,说明土霉素对小麦幼苗体内的抗氧化系统具有破坏作用.该实验结果显示,低浓度土霉素长期暴露对小麦幼苗的生长发育具有不良的生态毒性效应.     

铜锈环棱螺对镉污染沉积物慢性胁迫的生物标志物响应

沉积物毒性测试是评价水生态系统中沉积物污染生态风险的重要手段.建立合适的毒性测试生物是进行沉积物毒性测试的基本前提.铜锈环棱螺(Bellamya aeruginosa)在我国淡水水体中分布广泛,具有重要的生态价值.本研究将实验室培养的铜锈环棱螺暴露于不同含量的镉加标沉积物中28d,以评价该物种在镉污染沉积物慢性胁迫下生物标志物响应的敏感性.结果表明,除了谷胱甘肽(GSH)相对不敏感外,壳长增长率、肝胰脏超氧化物歧化酶(SOD)和过氧化氢酶(CAT)、以及肝胰脏和肾脏中的金属硫蛋白(MT)均表现出相对较高的敏感性,可用作重金属污染沉积物慢性胁迫的有效生物标志物.尤其是肝胰脏SOD和CAT可以用作指示低水平镉污染沉积物长期污染胁迫下的敏感生物标志物.此外,该物种的实验室培养和毒性测试操作容易进行,可以考虑将铜锈环棱螺作为我国淡水沉积物毒性评价的候选物种.     

预防职业病有妙招

正近几年,职业病已经成为伤害我们劳动人民的罪魁祸首。所从事的工作岗位不同,其职业病的危害因素、程度也有所不同。根据重庆市疾病预防控制中心专家介绍,如果员工在做好劳动保护的同时,能科学合理安排饮食,正确利用饮食获得良好的营养素,也可有效地预防、减轻职业病危害因素所致的健康危害。接触粉尘作业的工人可常吃些猪血,猪血中的血浆蛋白经胃酸的分解能产生一种可润肠解毒的物质,有利于体内尘毒的排出。     

肝素钠生产废水处理及蛋白回收

肝素钠生产废水中Cl-含量及盐度均较多,并且w(蛋白质)为1.68%,ρ(COD_Cr)为31 968 mg/g,处理难度大.为探究其净化和回收蛋白的方法,首先对FeCl₃·6H₂O、FeSO₄·7H₂O、KAl(SO₄)·12H₂O进行粗筛,选择FeCl₃·6H₂O为无害蛋白絮凝剂;再通过单因素试验和Box-Benhnken-Design响应面法,考察了FeCl₃·6H₂O投加量、膨润土投加量、硅藻土投加量及pH对蛋白沉淀量的影响及交互作用;建立了蛋白回收的数学模型.结果表明,各因素对蛋白沉淀量的影响为:X₂X₄(硅藻土投加量与pH的交互项)>X₄(硅藻土投加量)>X₁X₃(FeCl₃·6H₂O投加量与膨润土的交互项)>X₁(FeCl₃·6H₂O投加量)>X₁X₄(FeCl₃·6H₂O投加量与硅藻土投加量的交互项);在最佳反应条件(pH为7.5,FeCl₃·6H₂O添加量为0.38%,膨润土投加量为1.90%,硅藻土添加量为4.25%)下蛋白沉淀量达0.82%,与预测值的偏差为3.50%.研究显示,在最佳反应条件下COD_Cr去除率达80.94%,减轻了废水后期的处理难度.      

基于三维荧光光谱的鄱阳湖湿地水体有色可溶性有机物组成特征和来源

有色可溶性有机物(Chromophoric dissolved organic matter,CDOM)是水生生态系统的重要组成部分,在生物地球化学循环过程中起着重要的作用.本研究基于2021年4月鄱阳湖南矶湿地国家级自然保护区内3个碟形湖(战备湖、白沙湖和东湖)28个采样点的水样和实测水质参数数据,运用紫外-可见吸收...