西江野生斑鱯乳酸脱氢酶和酯酶同工酶的电泳研究

斑鱯(Mystus guttatus)俗称魽鱼、芝麻鲶、梅花鲶、西江魽、白须魽,属鲇形目鲿科鱯属。主要分布于珠江水系的东江、北江、西江以及海南岛的南渡江水系[1]。斑鱯为无鳞鱼,栖息于江河底层,以小型水生动物为食,其肉质嫩滑,肉味鲜美,与卷口鱼、鳜鱼、鲈鱼一起被誉为珠江四大名鱼[2]。同工酶标记技术是研究鱼类遗传特征的一种重要方法,同工酶作为一项生化遗传指标广泛应用于鱼类的系统进化、群体遗传、杂交育种、个体发育、病理生理和环境保护等方面[3]。国内外许多学者利用这一方法对鱼类进行了许多生化遗传学研究,为鱼类的群体遗传和进化研究…     

Acute toxicity of organochlorine insecticide endosulfan to the giant freshwater prawn Macrobrochium rosenbergii

Endosulfan, an organochlorine pesticide, is highly toxic and effective at controlling pests in agriculture, horticulture, and public health programs. In this study, static bioassays were used to evaluate the toxicity of endosulfan to freshwater prawns( Macrobrachium rosenbergii) of various lengths(1.5±0.03,4±0.08, and 7±0.06 cm). Additionally, the activities of peroxidase(POD), acid phosphatase(ACP),alkaline phosphatase, acetylcholinesterase(AChE), and Na + /K +-ATPase were analyzed to refl ect the effects of endosulfan exposure. The 96 h LC 50 of endosulfan for prawns 1.5, 4, and 7 cm long were 1.86, 4.53,and 6.09μg/L, respectively, improved tolerance to endosulfan with growth. The POD activities of test organisms exposed to low concentrations of endosulfan were inhibited, indicating the presence of oxygen damaged tissue. Moreover, a notable decrease in AChE activity was observed due to overstimulation of neurotransmission, which might result in abnormal behavior. The effect caused by endosulfan on phosphatase production in the hepatopancreas of prawns 1.5, 4, and 7 cm long was different because the ability of nonspecifi c immune regulation increased with growth. The 96 h LC 50 values obtained in this study could be used in the formulation of water-quality criteria in China. Moreover, the changes in enzymes activities of M. rosenbergii under stress of endosulfan could be applied in the establishment of early warning indicators for bio-safety.     

Cloning and characterization of a thermostable carboxylesterase from inshore hot spring thermophile Geobacillus sp. ZH1

The gene(741 bp) encoding carboxylesterase from the thermophilic bacterium Geobacillus sp.ZHl was cloned and overexpressed in Escherichia coli.The purified recombinant protein presented a molecular mass of about 40 kDa by SDS-PAGE analysis.Enzyme assays using p-nitrophenyl esters with different acyl chain lengths as the substrates confirmed its esterase activity,yielding highest specific activity with p-nitrophenyl acetate.Among the p-nitrophenyl esters tested,the carboxylesterase presented preference for p-nitrophenyl caprylate,but hydrolyzed p-nitrophenyl butyrate more efficiently.When p-nitrophenyl butyrate was used as a substrate,the recombinant carboxylesterase exhibited highest activity at pH 8.0 and 60℃.Almost no decrease in esterase activity was observed at 60℃for 3 h,and over 40% of activity was still maintained after incubation at 90℃for 3 h.These results indicate that Geobacillus sp.ZH1 recombinant esterase was thermostable.The enzymatic activity was inhibited by the addition of phenylmethylsulfonyl fluoride,indicating that it contains serine residue,which plays a key role in the catalytic mechanism.Except SDS and xylene,this esterase showed stability toward other tested detergents and organic solvents.Cloning,expression,and biochemical characterization of Geobacillus sp.ZH1 carboxylesterase lay a good foundation for its structural characterization and industrial application.     

试论沙冬青属的染色体地理*

沙冬青属是我国西北干旱地区及中亚东部荒漠的一个特有属,是我国荒漠中唯一的旱生常绿阔叶灌木,本文采用细胞学的方法,研究沙冬青属2种植物及其近缘属──黄花木属和黄华属在青藏高原的代表种(黄花木、紫花黄华)的核型、酯酶同工酶,进而探讨沙冬青属的演化趋势、地理分布及与环境的关系。本文是植物染色体地理的试验研究。     

海洋土曲霉C23-3与不同类型海洋微生物共培养对其次生代谢产物的影响

【目的】研究海洋土曲霉C23-3与不同类型海洋微生物共培养对其次生代谢产物的影响,挖掘土曲霉菌株C23-3的次生代谢潜力。【方法】将副溶血弧菌、枯草芽孢杆菌和胶红酵母的活菌或灭活菌体分别以不同时间与土曲霉C23-3共培养;采用DPPH自由基清除法和Ellman法分别评价各提取物的抗氧化和乙酰胆碱酯酶抑制活性,采用滤纸片法比较各提取物的抗菌活性,采用HPLC指纹图谱分析各提取物化学成分的差异。【结果与结论】发现不同类型的微生物与土曲霉共培养均可激活一些原本沉默的活性次级代谢产物;菌株及共培养物的化学拮抗能力、HPLC指纹图谱中的特征代谢产物变化揭示在活菌培养体系中土曲霉占竞争优势;而且灭活菌体中可能存在某些信号物质,在12 d时对土曲霉群体自感应信号分子丁内酯-I的产生具有比活菌更强的刺激作用。研究结果为深入挖掘海洋真菌代谢潜力及抗老年痴呆等活性先导化合物的发现提供基础。     

黄鱼(Hexagrammos otakii)脑组织AChE的亲和层析

采用亲和层析法对黄鱼脑组织的乙酰胆碱酯酶进行分离纯化。纯化酶最大比活力为63．136U／mg蛋白，最适pH为8，最适反应温度为35℃。此酶经过SDS-PAGE呈一条带，表明其纯度达电泳纯。对纯化酶进行底物特异性、过量底物抑制效应和抑制剂选择性检验，结果证实该酶为乙酰胆碱酯酶。     

基于FIA和光学原理的酶传感器检测海水甲基对硫磷

将乙酰胆碱酯酶(acetylcholinesterase,AChE)传感器与流动注射系统(flow injection analysis system,FIA)相结合,通过光学方法测定固定化酶受农药抑制后的残余活性,对海水中微量甲基对硫磷进行定量分析。该系统的适宜工作条件为:温度30℃;固定化酶的用量0.05 U;载液流速0.45 mL/min;进样时间20 min;底物(碘化硫代乙酰胆碱)溶液浓度0.100 mol/L,注射量100μL。在0.1~100μg/L之间,农药浓度的对数值与固定化酶活性的抑制率之间具有良好的线性关系(r=0.995 3)。利用该系统检测含甲基对硫磷分别为0.8μg/L和5.0μg/L的模拟海水样品,获得了较好的准确度和精密度,平均相对误差和变异系数均小于10%。     

枝管藻多糖对久效磷暴露水体中鱼类保护作用的研究

以金鱼(Carassius auratus)体内超氧化物歧化酶(Superoxide dismutase，SOD)活力、乙酰胆碱酯酶(Acetylcholinesteras，AChE)活力变化为指标，观察了枝管藻多糖对久效磷暴露的水体中鱼类生理功能的影响。结果表明：用枝管藻多糖灌胃鲫鱼15d，枝管藻多糖能显著降低久效磷对鱼类体内SOD活力的诱导和有效阻止久效磷对鱼类中枢神经系统AChE活性的抑制，具有拮抗久效磷农药对鱼类毒害的作用。     

东海近海赤潮水体中酯酶活性测定及其意义

测试了东海正常海水与赤潮暴发时水体中的酯酶浓度，初步研究了营养盐的变化与酯酶浓度及其赤潮暴发的关系，发现赤潮暴发时水体的酯酶浓度大大高于正常海水，表明在赤潮暴发水体中浮游植物大量裂解死亡。     

久效磷对单环刺螠体内几种酶活性影响的初步研究

运用冰冻切片技术和酶组织化学的方法研究了长期暴露于不同质量浓度久效磷(0,50,100,150ng/L)下的单环刺螠(Urechisunicinctus)体内的乙酰胆碱酯酶(AChE)、细胞色素C氧化酶(CCO)、碱性磷酸酶(AKP)的活性变化。实验表明,AChE在单环刺螠的体壁上呈现出较强的酶活性,活性位点处为红棕色的颗粒沉淀、并随久效磷胁迫浓度的提高显色越来越深;消化道切片上基本上没有AChE的活性。CCO在单环刺螠的体壁及肠道上都呈现出较强的酶活性,活性位点显示为棕色;肠道上,不同质量浓度组由低到高其CCO活性位点依次增多、显色也依次加深。低质量浓度久效磷(<150ng/L)胁迫对单环刺螠体内的AKP活性没有明显的影响。