东亚地区低层大气环流季节性变化与粘虫远距离迁飞

我国位于盛行的东亚季风区域内,季节变化明显。粘虫(Mythimna separata Walker)远距离北迁南回,与东亚地区低层大气环流季节性变化有着密切的关系。因此根据诱蛾资料和气象观测记录,着重对我国粘虫的迁飞方向、迁飞高度、迁飞界限、起飞降落条件以及虫源基地等问题进行分析,绘制我国粘虫迁飞路径图,是十分必要的。     

3-氰基吡啶水合酶产生菌的筛选及其酶形成条件

应用富集培养和梯度底物浓度定向筛选技术,从长期被腈化物污染的土壤中筛选到一株产 3-氰基吡啶水合酶(3-cyanopyridine hydratase)活性较高的马红球菌(Rhodococcus e-qui)SHB-121.研究了该菌3-氰基吡啶水合酶的最适形成条件.在最适条件下,酶的比活力达5.3u/mg干细胞,比在初筛条件下的酶活力提高95倍,而在其细胞内共存的尼克酰胺(烟酰胺)水解酶活力很低.     

河南济源晚石炭世太原组的一种复体四射珊瑚

Ａｃｒｏｃｙａｔｈｕｓ是一类块状体或丛状体的四射珊瑚，在北美分布于下石炭统，我国见于上石炭统，但丛状体的在我国系首次发现。在连续切片上，可见两个生长阶段，其繁殖方式有侧芽繁殖和边缘泡沫板内繁殖，系统分类上另置独立的科级分类。根据形态分析，该珊瑚栖息在动水，能量略高及食料丰富的浅水环境。当前标本为一新种：Ａ．ｊｉｙｕａｎｅｎｓｉｓｓｐ．ｎｏｖ．。     

Characterization of the 16S rRNA- and membrane-binding domains of Streptococcus pneumoniae Era GTPase: structural and functional implications.

Era is a highly conserved GTPase essential for bacterial growth. The N-terminal part of Era contains a conserved GTPase domain, whereas the C-terminal part of the protein contains an RNA- and membrane-binding domain, the KH domain. To investigate whether the binding of Era to 16S rRNA and membrane requires its GTPase activity and whether the GTPase domain is essential for these activities, the N- and C-terminal parts of the Streptococcus pneumoniae Era - Era-N (amino acids 1-185) and Era-C (amino acids 141-299), respectively - were expressed and purified. Era-C, which had completely lost GTPase activity, bound to the cytoplasmic membrane and 16S rRNA. In contrast, Era-N, which retained GTPase activity, failed to bind to RNA or membrane. These results therefore indicate that the binding of Era to RNA and membrane does not require the GTPase activity of the protein and that the RNA-binding domain is an independent, functional domain. The physiological effects of the overexpression of Era-C were assessed. The Escherichia coli cells overexpressing Era and Era-N exhibited the same growth rate as wild-type E. coli cells. In contrast, the E. coli cells overexpressing Era-C exhibited a reduced growth rate, indicating that the overexpression of Era-C inhibits cell growth. Furthermore, overexpression of era-N and era-C resulted in morphological changes. Finally, purified Era and Era-C were able to bind to poly(U) RNA, and the binding of Era to poly(U) RNA was significantly inhibited by liposome, as the amount of Era bound to the RNA decreased proportionally with the increase of liposome in the assay. Therefore, this study provides the first biochemical evidence that both binding sites are overlapping. Together, these results indicate that the RNA- and membrane-binding domain of Era is a separate, functional entity and does not require the GTPase activity or the GTPase domain of the protein for activity.     

Computer Simulation of Clostridium botulinum Strain 56A Behavior at Low Spore Concentrations

It is generally assumed that spore behavior is independent of spore concentration, but recently published mathematical models indicate that this is not the case. A Monte Carlo simulation was employed in this study to further examine the independence assumption by evaluating the inherent variance in spore germination data. All simulations were carried out with @Risk software. A total of 500 to 4,000 iterations were needed for each simulation to reach convergence. Lag time and doubling time from a higher inoculum concentration were used to simulate the time to detection (TTD) at a lower inoculum concentration under otherwise identical environmental conditions. The point summaries of the simulated and observed TTDs were recorded for the 26 simulations, with kinetic data at the target inoculum concentration. The ratios of the median (R_m = median_obs/median_sim) and 90% range (R_r = 90% range_obs/90% range_sim) were calculated. Most R_m and R_r values were greater than one, indicating that the simulated TTDs were smaller and more homogeneous than the observed ones. R_r values departed farther from one than R_m values. Ratios obtained when simulating 1 spore with 10,000 spores deviated the farthest from one. Neither ratio was significantly different from the other when simulating 1 spore with 100 spores or simulating 100 spores with 10,000 spores. When kinetic data were not available, the percent positive observed at the 95th percentile of the simulated TTDs was obtained. These simulation results confirmed that the assumption of independence between spores is not valid.     

Flavin-containing monooxygenase: a major detoxifying enzyme for the pyrrolizidine alkaloid senecionine in guinea pig tissues

Evidence based on optimal pH, thermal stability, and enzyme inhibition data suggests that the NADPH-dependent microsomal N-oxidation of the pyrrolizidine alkaloid senecionine is carried out largely by flavin-containing monooxygenase in guinea pig liver, lung, and kidney. In contrast, the hepatic microsomal conversion of senecionine to the pyrrole metabolite (+/-)-6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP) is catalyzed largely by cytochrome P450. However, the rate of senecionine N-oxide formation (detoxication) far exceeded the rate of DHP formation (activation) in guinea pig liver microsomes over a range of pHs (pH 6.8 to 9.8). In guinea pig lung and kidney microsomes, N-oxide was the major metabolite formed from senecionine with little or no production of DHP. The high rate of detoxication coupled with the low level of activation of senecionine in liver, lung, and kidney may help explain the apparent resistance of the guinea pig to intoxication by senecionine and other pyrrolizidine alkaloids.     

Characterization of a new substrate for protein kinase C: assay by continuous fluorometric monitoring and high performance liquid chromatography

A synthetic peptide derived from the phosphorylation site in the beta-subunit of phosphorylase kinase (RTKRSGSVYEPLKI) is an efficient substrate for rat brain protein kinase C: Km = 18 +/- 2 microM and Vmax = 2.1 +/- 0.1 mumol/min/mg. The phosphorylation of the peptide, which occurs at Ser7, can be followed by four independent procedures. 1. Standard measurement of 32P incorporation. 2. Reverse phase HPLC in a gradient system containing 0.1 M ammonium sulfate in the stationary phase. 3. Continuous fluorometric monitoring of the changes in intrinsic peptide fluorescence. 4. Continuous fluorometric determination of NADH oxidation in a coupled enzyme assay.     

Comparison of rainbow trout and mammalian cytochrome P450 enzymes: evidence for structural similarity between trout P450 LMC5 and human P450IIIA4

Studies were undertaken to determine the immunochemical relationship between constitutive trout cytochrome P450s and mammalian cytochrome P450IIIA enzymes. Polyclonal antibodies (IgG) generated against trout P450 LMC5 reacted strongly with P450IIIA1 in dexamethasone-induced rat liver microsomes and with P450IIIA4 in human liver microsomes in immunoblots. In contrast, rabbit anti-P450 LMC1 IgG did not recognize these proteins in rat and human liver microsomes. Reciprocal immunoblots using anti-rat P450IIIA1 showed that this antibody does not recognize trout P450 LMC1 or LMC5. However, anti-human P450IIIA4 IgG was found to cross react strongly with P450 LMC1 and LMC5. Progesterone 6 beta-hydroxylase activity of trout liver microsomes, a reaction catalyzed by P450 LMC5, was markedly inhibited by anti-P450IIIA4 and by gestodene, a mechanism-based inactivator of P450IIIA4. These results provide evidence for a close structural similarity between trout P450 LMC5 and human P450IIIA4.     

Estimating equations for parameters in means and covariances of multivariate discrete and continuous responses.

Generalized estimating equations are introduced in an ad hoc fashion for the covariance matrix of a multivariate response. These equations are to be solved jointly with score equations from a generalized linear model for mean parameters. A class of quadratic exponential models is used to develop joint estimating equations for mean and covariance parameters in a more systematic fashion, and proposals for the use of such equations are developed. Comments on the relative merits of the ad hoc and model-based approaches to estimation are given and a regression illustration with a bivariate response is provided.     

Fractal analysis of protein chain conformation

This paper presents a simple practical method for characterizing conformation of protein chains. A single number Df, as the fractal dimension, is assigned to each chain. Df = Ln(N)/Ln(N.d/L), where N is the number of the amino acid residues in the chain, L and d are the total length and the planar diameter of the chain, respectively. In general, 1 less than Df less than or equal to 2, which is related to the shape of the protein chain. These values are different from those of Stapleton's group, but in agreement with computer simulations.