近亲裸腹溞对海水盐度的适应性

为了解淡水枝角类对海水盐度的适应性,在实验室内采用种群实验生态学方法研究25 ℃±0.5 ℃恒温条件下不同盐度（0、1、2、3、4、5）对近亲裸腹溞(Moina affinis)生存、生长和生殖的影响.结果表明,在各盐度梯度范围内,近亲裸腹溞的平均寿命随盐度升高而缩短,盐度4和5组内禀增长率与其它各组差异显著;盐度4和5组平均每窝产幼量与对照及其他组差异显著.一生产幼量除盐度1组和对照组较高外,其他各组均显著下降.对照组体长增长幅度与日增长率均低于各处理组.日增长率随着盐度的升高而增大.个体平均每胎产幼量以盐度1、2组最高.盐度5为近亲裸腹溞的生存和生殖盐限,但经过短期的海水驯化,其生殖耐盐上限有所提升,可达6.5.     

微波和电场对蒙古裸腹溞存活、生长和生殖的影响

研究了微波和电场对蒙古裸腹溞存活、生长和生殖的影响.结果表明: 35 s以上的2 450 MHz的微波辐照对蒙古裸腹溞的致死效应明显.短时间(<25 s)微波处理显著提高了蒙古裸腹溞的每窝产幼量及一生产幼量,其中10 s微波处理组一生产幼量最高.微波处理使蒙古裸腹溞的寿命显著延长(总寿命15.8～18 d).短时间的微波处理对幼溞的发育无显著影响,但对成溞的生长具有一定的抑制作用.脉冲电场可大幅提高蒙古裸腹溞的一生产幼量, 其中29 kV·cm^-1的脉冲电场效果最佳; 高压静电场对蒙古裸腹溞的繁殖无显著影响.高压静电场和脉冲电场对幼溞的发育均无显著影响,高压静电场对成溞的生长影响不明显,而脉冲电场则对成溞的生长具有一定的抑制作用,且电压越高,抑制作用越明显.     

亚热带浅水湖泊中两种裸腹溞生活史特征的比较

以来自武汉南湖的远东裸腹溞和江苏太湖的微型裸腹溞为对象,在温度为(25±1)℃、食物条件为2×10~5cells·mL~(-1)斜生栅藻下,研究了两种裸腹溞的体长、成熟时间、存活率、寿命和产幼溞数等生活史参数。结果表明:两种裸腹溞的体长均随着龄数增加呈现递增的趋势;远东裸腹溞的成熟时间(P=0.008)和首次产幼溞时间(P=0.022)均显著小于微型裸腹溞,而其成熟体长(P0.001)、寿命(P=0.003)和首次产幼溞数(P0.001)均显著大于微型裸腹溞;远东裸腹溞和微型裸腹溞的内禀增长率分别为0.73和0.49 ind·d~(-1);Pearson相关性分析显示,远东裸腹溞(r=0.659,P=0.008)和微型裸腹溞(r=0.649,P=0.009)的首次产幼溞数与成熟体长间均呈极显著相关;江苏太湖的微型裸腹溞的成熟时间长,而武汉南湖的远东裸腹溞的生殖能力更强,这可能与两种裸腹溞的遗传结构及它们对环境适应等差异有关。     

百草枯和草甘膦对多刺裸腹溞的毒性效应

采用急性毒性实验方法研究了两种常见除草剂百草枯和草甘膦对多刺裸腹溞(Moina macrocopa)的48hLC50值,应用生命表实验方法研究了亚致死浓度的百草枯(0、0.01和0.04mg·L-1)和草甘膦(0、0.4和1.6mg·L-1)对多刺裸腹溞生命表统计学参数的影响。结果表明:百草枯和草甘膦对多刺裸腹溞的48hLC50值分别为0.626和26.287mg·L-1;百草枯浓度对多刺裸腹溞的生命期望、世代时间、净生殖率和种群内禀增长率有显著影响(P<0.01),草甘膦浓度对多刺裸腹溞的生命期望、世代时间和种群内禀增长率有显著影响(P<0.01),百草枯和草甘膦的交互作用对多刺裸腹溞的世代时间和种群内禀增长率有显著影响(P<0.01)。多重比较显示:当忽略草甘膦的影响时,0.01mg·L-1的百草枯使多刺裸腹溞的生命期望显著延长,而0.04mg·L-1的百草枯则相反,0.04mg·L-1的百草枯使多刺裸腹溞的净生殖率显著降低;当忽略百草枯的影响时,0.4和1.6mg·L-1的草甘膦均使多刺裸腹溞的生命期望显著缩短;与空白对照组相比,0.01mg·L-1的百草枯和1.6mg·L-1的草甘膦混合液使多刺裸腹溞的世代时间显著延长;而0.04mg·L-1的百草枯和0、0.4、1.6mg·L-1的草甘膦混合液均使多刺裸腹溞的世代时间显著缩短,种群内禀增长率显著降低。随着草甘膦浓度的升高,0.04mg·L-1的百草枯对多刺裸腹溞的毒性显著降低,表现出明显的拮抗作用。     

碱度和pH对两品系蒙古裸腹溞(Moina mongolica Daday)存活、生长和生殖的影响

在温度为(25±0.5)℃,盐度为31.5±0.5的条件下,研究了碱度和pH对两品系蒙古裸腹溞的存活、生长和生殖的影响.结果表明,两品系蒙古裸腹溞在培养液的pH 6～8时,生长率和存活率显著高于其他各组;晋南品系的内禀增长率最大为0 5758 ind · d-1,内蒙品系的内禀增长率最大为0.5519 ind · d-1.碱度的实验表明,两品系蒙古裸腹溞在培养液的碱度为2.05到4.58 mmol · L-1时,生长率和存活率显著高于其他各组;晋南品系的内禀增长率最大为0.5573 ind · d-1,内蒙品系的内禀增长率最大为0.5376 ind · d-1.在相同的实验条件下,两品系体长的增长差异不大,但各生殖参数晋南品系大多高于内蒙品系.两品系蒙古裸腹溞存活的最适pH为6～8,最适碱度为2.05到4.58mmol · L-1,晋南品系对于碱度和pH的适应能力大于内蒙品系.     

钼对多刺裸腹溞的毒性

运用急性毒性和生命表实验方法,研究了钼对多刺裸腹溞(Moina macrocopa)的急性毒性和生命表统计学参数的影响。结果表明,钼对多刺裸腹溞的48hLC50值为134.46mg·L-1,95%置信区间为107.05～194.53mg·L-1;在2.0～15.0mg·L-1的浓度范围内,钼对多刺裸腹溞的生命期望、世代时间、平均寿命和净生殖率均无显著影响,但对种群内禀增长率有显著影响。空白对照组中,多刺裸腹溞的种群内禀增长率为0.0448±0.0033h-1,显著高于6.4、8.4、11.2和15.0mg·L-1钼浓度下多刺裸腹溞的种群内禀增长率(分别为0.0334±0.0007、0.0327±0.0010、0.0335±0.0003和0.0346±0.0005h-1)。与其他已测试的物种相比,多刺裸腹溞对钼具有较强的敏感性;在所研究的生命表统计学参数中,种群内禀增长率是最敏感的指标。     

共培养大型海藻对蒙古裸腹溞培养体系的生态效应

为了解大型海藻与盐水枝角类共培养的生态作用,通过大型海藻与蒙古裸腹溞共培养的方法,研究了孔石莼和肠浒苔对共培养水体水质的静态净化效果以及对该溞生殖与种群增长的影响。结果表明:孔石莼和肠浒苔对共培养水体氨氮(NH3-N)、pH和溶解氧(DO)的影响显著(P0.05)且变化规律基本一致,其中NH3-N在第12 d降到最低(0.016mg·L~(-1)),随后维持在相对稳定范围内; pH和DO随孔石莼和肠浒苔生物量的增加而升高,pH变化范围8.2～9.0,DO变化范围4.2～6.4 mg·L~(-1);共培养条件下两种大型海藻对蒙古裸腹溞生殖和种群增长的影响表现出明显差异,在孔石莼共培养体系中,蒙古裸腹溞的平均生殖量、内禀增长率rm、周限增长率λ和世代周期T随孔石莼生物量的增加呈波动升高,当生物量为2.5 g·L~(-1)时均达峰值,之后逐渐下降,平均寿命随孔石莼生物量的增加而减少;孔石莼共培养体系显著优于对照组单一蒙古裸腹溞培养效果(P0.05),而肠浒苔共培养体系与对照组相差不显著(P0.05)。研究结果证明了孔石莼对共培养体系水质和养殖动物的有利作用,即共培养一定生物量(2.5～3.5 g·L~(-1))的孔石莼不但有利于培养水体中NH3-N、DO等水质净化,还可以促进蒙古裸腹溞的生长与繁殖,为蒙古裸腹溞规模化培养工艺优化与新模式构建提供了科学依据。     

艾氏剂对连续三个世代多刺裸腹溞生命表统计学参数的影响

利用生命表技术对连续3个世代暴露于不同浓度(20、40、80、160、320μg/L和640 μg/L)艾试剂(aldrin)溶液中的多刺裸腹溞(Moina macrocopa)生命表统计学参数进行了研究.结果表明:艾试剂对3个世代多刺裸腹溞所有生命表统计学参数均有显著性影响(P<0.05).与空白对照组相比,浓度高于80 μg/L的艾氏剂使多刺裸腹溞母代的生命期望和净生殖率显著降低;浓度高于160 μg/L的艾氏剂使母代的世代时间显著缩短,种群内禀增长率显著降低.浓度高于40 μg/L的艾氏剂使多刺裸腹溞F1代的生命期望显著缩短,20μg/L和80～640 μg/L的艾试剂使F1代的净生殖率显著降低,320μg/L和640 μg/L的艾氏剂使F1代的世代时间显著缩短,所有浓度的艾试剂均使F1代的种群内禀增长率显著降低.160～640 μg/L的艾氏剂使多刺裸腹溞F2代的生命期望和世代时间显著缩短,160 μg/L和640 μg/L的艾氏剂使F2代的净生殖率显著降低;除40和320 μg/L外,所有浓度的艾试剂均显著提高了F2代的种群内禀增长率.在实验设置的艾试剂浓度范围内,除F2代种群内禀增长率外,3个世代多刺裸腹溞的所有生命表统计学参数均与艾试剂浓度呈曲线相关.在慢性毒性试验中,污染物对多刺裸腹溞生命表统计学参数的影响因其暴露时所处发育时期和持续暴露世代数的不同而存在着重要的差异.     

硫丹和狄氏剂对多刺裸腹的毒性效应

为了解亚致死浓度的有机氯农药硫丹和狄氏剂对枝角类的急性、慢性和联合毒性作用,采用急性毒性实验方法研究了硫丹和狄氏剂对多刺裸腹溞(Moina macrocopa)的48 h半效应浓度,应用生命表实验方法研究了亚致死浓度的硫丹(0、52和208 μg/L)和狄氏剂(0、12和48μg/L)对多刺裸腹溞生命表统计学参数的影响.结果表明,硫丹及狄氏剂对多刺裸腹溞的48 h半效应浓度是834.9和185.8 μg/L.硫丹对多刺裸腹溞出生时的生命期望(e0)、世代时间(T)和净生殖率(R0)有显著的影响(P<0.05),但对种群内禀增长率(rm)没有显著的影响(P>0.05);狄氏剂仅对种群内禀增长率有显著的影响(P<0.05);硫丹与狄氏剂的交互作用对所有生命表统计学参数均无显著影响(P>0.05).与硫丹浓度为0时相比,52和208μg/L的硫丹均使多刺裸腹溞的e0.和T显著缩短,R0显著降低;与狄氏剂浓度为0时相比,48μg/L的狄氏剂使多刺裸腹溞的rm显著升高.这说明硫丹与狄氏剂对多刺裸腹溞的联合作用形式是独立相加,没有产生协同作用.     

温度和食用藻密度对发头裸腹溞种群动态和两性生殖的影响

研究了不同温度和食用藻密度对发头裸腹溞种群动态和两性生殖的影响.结果表明： 温度、食用藻密度对发头裸腹溞的种群密度、雄体密度和卵鞍数均有显著影响.高食用藻密度组的发头裸腹溞种群密度明显高于中、低食用藻密度组,其最大种群密度出现在20 ℃下的高食用藻密度组.在相同的温度下,发头裸腹溞的首次产幼溞数随食用藻密度的降低而减少,平均每个母溞首次产出的最大幼溞数出现在25 ℃下的高食用藻密度组.高食用藻密度组发头裸腹溞产生的雄体密度明显高于中、低食用藻密度组.发头裸腹溞的雄体密度与其种群密度之间存在极显著的相关性.发头裸腹溞所产的卵鞍数随食用藻密度的下降而下降,且25 ℃下发头裸腹溞所产的卵鞍数明显高于其他温度组.与温度相比,食用藻密度对发头裸腹溞的种群动态和两性生殖的影响更大.     

The synthetic rate of dipeptide catalyzed by organic solvent-stable protease from Pseudomonas aeruginosa PST-01 in the presence of water-soluble organic solvents

The initial synthetic rates of peptide Cbz-Arg-Leu-NH(2) from Cbz-Arg and Leu-NH(2) using PST-01 protease in the presence and absence of organic solvents were investigated under various conditions. The synthetic rates of Cbz-Arg-Leu-NH(2) in the presence of 50% (v/v) methanol, 50% (v/v) N,N-dimethylformamide (DMF) and 60% (v/v) dimethyl sulfoxide (DMSO) were 1.6-, 2.4-, and 5.1-times higher than that in the absence of organic solvent, respectively. The PST-01 protease was not only stable in the presence of organic solvents but also exhibited high reaction rates in the presence of methanol, DMF, and DMSO. When the Cbz-Arg concentration was lower than 60mM or the Leu-NH(2) concentration was lower than 400mM, the initial rates increased lineally with increase in their concentrations. However, the rates did not increase when the Leu-NH(2) concentration was more than 500mM. The optimum temperature and pH of the reaction were 40 degrees C and 7.0, respectively.     

New derivatives of D-mannaric and galactaric acids. Synthesis of a new stereoregular Nylon 66 analog from carbohydrate-based monomers having the D-manno configuration

2,3,4,5-Tetra-O-methyl-D-mannaric and galactaric acids and their bis(pentachlorophenyl) esters have been prepared as crystalline compounds, in good yields, from D-mannitol and galactitol, respectively. A new stereoregular polyamide, analogous to Nylon 66, has been prepared by polycondensation of bis(pentachlorophenyl) 2,3,4,5-tetra-O-methyl-D-mannarate with 1,6-diamino-1,6-dideoxy-2,3,4,5-tetra-O-methyl-D-mannitol dihydrochloride. The polymer has a M(w) of 31,100 with a polydispersity of 1.5 (GPC). It was highly hygroscopic and soluble in ethanol, acetone, dimethyl sulfoxide, N,N-dimethylformamide and chloroform, but only slightly soluble in water.     

Inhibitory effect of organic solvents on the mutagenicity of N-nitrosodialkylamines in Salmonella

The influence of organic solvents on the mutagenicity of 11 N-nitrosamines was examined in Salmonella typhimurium TA100 using the Ames's liquid incubation assay in the presence of rat-liver S9. The mutagenic activities of N-nitrosodimethylamine, N-nitrosodiethylamine, 6 oxidative derivatives of N-nitrosopropylamine and N-nitroso-2,6-dimethylmorpholine were considerably decreased by addition of dimethyl sulfoxide, dimethyl formamide, acetone, 95% ethanol or acetonitrile, which are recommended for use as solvents in the assay by Ames's group, to the incubation mixture. The mutagenic activities of N-nitrosodipropylamine and N-nitrosodibutylamine, which are barely soluble in water, were also suppressed by increasing concentrations of dimethyl sulfoxide. These organic solvents did not appear to exert their influence by desmutagenic and antimutagenic actions. In contrast, the recoveries of unmetabolized carcinogens from preincubation mixtures and from agar plates were significantly higher in the presence of organic solvents than in their absence. The results indicate that the inhibitory effect is a result of interference with the process of metabolic activation by liver S9.     

A new method for extraction of iron-molybdenum cofactor (FeMoco) from nitrogenase adsorbed to DEAE-cellulose. 2. Solubilization of FeMoco in a wide range of organic solvents

While the iron-molybdenum cofactor (FeMoco) of nitrogenase, a constituent of the active site for nitrogen reduction, can be extracted into N-methylformamide (NMF) and pyrrollidinone, the inability to solubilize it in any other organic solvents has hampered further understanding of its structure and chemical properties. A method to solubilize FeMoco, prepared in N,N-dimethylformamide (DMF) with Bu4N+ as counterion [McLean, P. A., Wink, D. A., Chapman, S. K., Hickman, A. B., McKillop, D. M., & Orme-Johnson, W. H. (1989) Biochemistry (preceding paper in this issue)], in acetonitrile, acetone, methylene chloride, tetrahydrofuran, and benzene is reported. FeMoco evaporated to dryness in vacuo dissolves readily in good yield (55-100%) and with no significant loss in specific activity. In addition, FeMoco can be extracted directly into these solvents from MoFe protein bound to a DEAE-Sepharose column if the protein is pretreated with DMF. Methods have also been developed to extract fully active FeMoco into acetone and acetonitrile in the absence of any amide solvents (NMF or DMF). Extraction of FeMoco into acetone (30% yield) involves only pretreatment of column-bound protein with methanol, while extraction into acetonitrile (22% yield) requires pretreatment with methanol followed by THF. We conclude that the presence of a suitable soluble cation confers solubility to the cofactor in many common organic solvents and that the solubility of FeMoco in a given solvent may be independent of the ability of that solvent to extract the cofactor from column-bound protein.     

Mitochondrial morphology and function impaired by dimethyl sulfoxide and dimethyl Formamide

In this work, the effects of two non-ionic, non-hydroxyl organic solvents, dimethyl sulfoxide (DMSO) and dimethyl formamide (DMF) on the morphology and function of isolated rat hepatic mitochondria were investigated and compared. Mitochondrial ultrastructures impaired by DMSO and DMF were clearly observed by transmission electron microscopy. Spectroscopic and polarographic results demonstrated that organic solvents induced mitochondrial swelling, enhanced the permeation to H⁺/K⁺, collapsed the potential inner mitochondrial membrane (IMM), and increased the IMM fluidity. Moreover, with organic solvents addition, the outer mitochondrial membrane (OMM) was broken, accompanied with the release of Cytochrome c, which could activate cell apoptosis signaling pathway. The role of DMSO and DMF in enhancing permeation or transient water pore formation in the mitochondrial phospholipid bilayer might be the main reason for the mitochondrial morphology and function impaired. Mitochondrial dysfunctions induced by the two organic solvents were dose-dependent, but the extents varied. Ethanol (EtOH) showed the highest potential damage on the mitochondrial morphology and functions, followed by DMF and DMSO.     

Effects of the water-miscible organic solvents on lactoperoxidase purified from creek-water buffalo milk

Water buffalo lactoperoxidase (WBLPO) was purified with Amberlite CG-50 (NH₄ ⁺ form) resin, CM-Sephadex C-50 ion-exchange chromatography, and Sephadex G-100 gel-filtration chromatography from skimmed buffalo milk. The purity of the WBLPO was shown with SDS-PAGE. The R_z(A ₄₁₂/A ₂₈₀) value for the WBLPO was 0.9. The optimum pH for the WBLPO was at 6.0. The K _m value at optimum pH and 25°C was 0.13 mM. The V _max value at optimum pH and 25°C was 5.3 mol/min per ml. The K _i values for methanol, ethanol, dimethyl sulfoxide (DMSO), acetonitrile, isopropanol, tetrahydrofuran (THF), N,N"-dimethylformamide (DMF), and ethylene glycol were 1.087, 0.364, 0.302, 0.459, 0.330, 0.126, 0.093, and 2.125 M, respectively. All the solvents showed competitive inhibition. The I ₅₀ values of methanol, ethanol, dimethyl sulfoxide, acetonitrile, isopropanol, tetrahydrofuran, N,N"-dimethylformamide, and ethylene glycol were 2.910, 0.942, 0.537, 1.320, 0.875, 0.470, 0.405, and 3.920 M, respectively. Ethylene glycol, methanol, acetonitrile, and ethanol have been found to be very promising solvents for performing biocatalytic reactions with LPO in organic media.     

Inhibition of forskolin-activated adenylate cyclase by ethanol and other solvents

Ethanol and a variety of solvents are known to activate basal and Gpp(NH)p- and hormone-stimulated adenylate cyclase. We report here that ethanol and other solvents inhibit the activation of adenylate cyclase by forskolin. In the presence of 10 microM forskolin, 2% ethanol gives about 20% inhibition and 5% ethanol gives 40% inhibition of enzyme activity. Analysis of ethanol inhibition at several forskolin concentrations suggests that inhibition is competitive versus forskolin. Thus the effect of ethanol is greater at low forskolin concentrations and minimal at high concentrations. In addition to ethanol, inhibition of forskolin activation was observed with acetone, n-butanol, t-butanol, dimethyl formamide, dioxane, methanol and n-propanol. Dimethyl sulfoxide was inhibitory only at high concentrations (10%). Since some solvent is needed to prepare forskolin solutions and to maintain solubility at higher concentrations, the inhibitory effects reported here are an important consideration in studies employing forskolin activation. To minimize solvent inhibition we recommend that dimethyl sulfoxide be used to prepare forskolin solutions. At concentrations of 5% and less, dimethyl sulfoxide gives little if any inhibition of forskolin activation and causes only small increases in basal activity.     

Effect of organic solvents on the conformation and interaction of catalase and anticatalase antibodies

Effect of six organic solvents—methanol, ethanol, propanol, dimethyl sulphoxide (DMSO), N,N-dimethyl formamide (DMF), and glycerol on the conformation and interaction of catalase and anticatalase antibodies were studied with the aim of identifying the solvents in which antigen–antibody interactions are strong. The antigen binding activity of the antibodies in the various organic solvents increased in the following order: ethanol < methanol < no organic solvent < propanol < DMSO < DMF < glycerol. The structure of both the antibody and the antigen molecule was affected significantly in 40% concentration of the organic solvents used in this study. Catalase activity was inhibited in DMSO. However, the enzyme was activated in DMF upto about 50% of its concentration.     

Toxicity of solvents and surfactants to Amblyomma cajennense (Fabricius, 1787) (Acari: Ixodidae) and Dermacentor nitens (Neumann, 1897) (Acari: Ixodidae) larvae

The objective of this work was to verify the sensitivity of Amblyomma cajennense and Dermacentor nitens larvae to the solvents ethanol, methanol, acetone, xylol and dimethyl sulfoxide (DMSO) and the surfactant Tween 80. The first four solvents were tested at analytical purity while the DMSO and surfactant Tween 80 were tested at a concentration of 1%. The substances tested at analytical purity that caused high mortality were also tested at concentrations of 50%, 25% and 1%. The larval packet test was used, with 10 repetitions for each treatment. A control group was also formed with the same number of repetitions, in which the larvae were only exposed to distilled water. In the first experiment, only xylol was highly toxic at the concentrations tested, causing mortality above 90% for larvae of both species. In the second experiment, xylol at 1% and at 25% showed low toxicity to the A. cajennense and D. nitens larvae, respectively, since the percentage mortality was statistically similar to that of the control group (p>0.05).     

Stability of hydrolytic enzymes in water-organic solvent systems

The effects of organic solvents on the stabilities of bovine pancreas trypsin, chymotrypsin, carboxypeptidase A and porcine pancreas lipase were studied. Water-miscible solvents (ethanol, acetonitrile, 1,4-dioxane and dimethyl sulfoxide) and water-immiscible solvents (ethyl acetate and toluene) were used in 100 mM phosphate buffer (pH 7.0) or 100 mM Tris/HCl buffer (pH 7.0) in concentrations of 20–80% (v/v). All hydrolytic enzymes studied were inactivated by mixtures containing dimethyl sulfoxide at higher concentrations. Trypsin and carboxypeptidase A resisted solvent mixtures containing acetonitrile, 1,4-dioxane and ethanol. They preserved more than 80% of their starting activities during 20-min incubations. The activities of lipase and chymotrypsin decreased with increasing concentration of water-miscible polar organic solvents, but at higher concentrations (80%) 70–90% of the activity remained. In mixtures with water-immiscible solvents, the decrease in activity of carboxypeptidase A was pronounced. Trypsin and chymotrypsin underwent practically no loss in activity in the presence of toluene or ethyl acetate. In respect of stability, the polar solvent proved to be more favorable for lipase. These results suggest that the conformational stabilities of hydrolytic enzymes are highly dependent on the solvent-protein interactions and the enzyme structure.