Progesterone transformations as a diagnostic feature in the generaAlternaria,Stemphylium andCladosporium

Various species of the generaAlternaria, Stemphylium andCladosporium were shown to display a specific reaction characteristic for the given genus. In theAlternaria genus this is a 1-2-dehydrogenation of the A ring of the steroid molecule, inStemphylium 14α-hydroxylation and inCladosporium 7β-hydroxylation. This chemotaxonomic feature may supplement morphological and functional criteria in the taxonomy of filamentous fungi (Hyphomycetes).     

Purification and characterization of beta-glucosidase of Alcaligenes faecalis

A cellobiose-utilizing bacterium isolated from sugar cane bagasse and identified as a strain of Alcaligenes faecalis (ATCC 21400) produced an inducible beta-glucoside-splitting enzyme. The enzyme was purified by a series of streptomycin and ammonium sulfate fractionations and by Sephadex and diethylaminoethyl column chromatography. The final preparation was purified 130-fold, with a recovery of about 10% of the initial enzyme activity. The enzyme had a wide pH range, with optimal activity at pH 6.0 to 7.0. The enzyme was stable in solution at pH 6.5 to 7.8 when kept at 30 C for 2 hr, but it was destroyed by temperatures above 55 C. At 58 and 60 C, the time required to inactivate 90% of the initial activity was 16 and 6.5 min, respectively. An activation energy of 9,500 cal/mole and a K(m) of 1.25 x 10(-4)m were obtained by using p-nitrophenyl beta-glucoside as a substrate. The K(i) value and hydrolysis of cellobiose by the enzyme indicated a high affinity of the enzyme for the cellobiose. The enzyme had its specificity on beta-glucosidic linkage and the rate of hydrolisis of glucosides depended upon the nature of the aglycon moiety. The inactivation studies showed the presence of sulfhydryl groups in the enzyme. The activity of the enzyme was easily destroyed by the Cu(++) and Hg(++) ions. The Michaelis-Menton relationship and the rate of heat inactivation indicated the presence of one type of noninteracting active site in the bacterial beta-glucosidase. Molecular weight of the enzyme was estimated by gel filtration (Sephadex G-200) and sucrose density gradient, and a value of 120,000 to 160,000 was obtained.     

A neural network algorithm for the multiple traveling salesmen problem

We developed an efficient neural network algorithm for solving the Multiple Traveling Salesmen Problem (MTSP). A new transformation of the N-city M-salesmen MTSP to the standard Traveling Salesmen Problem (TSP) is introduced. The transformed problem is represented by an expanded version of Hopfield-Tank's neuromorphic city-position map with (N + M-1)-cities and a single fictitious salesmen. The dynamic model associated with the problem is based on the Basic Differential Multiplier Method (BDMM) [26] which evaluates Lagrange multipliers simultaneously with the problem's state variables. The algorithm was successfully tested on many problems with up to 30 cities and five salesmen. In all test cases, the algorithm always converged to valid solutions. The great advantage of this kind of algorithm is that it can provide solutions to complex decision making problems directly by solving a system of ordinary differential equations. No learning steps, logical if statements or adjusting of parameters are required during the computation. The algorithm can therefore be implemented in hardware to solve complex constraint satisfaction problems such as the MTSP at the speed of analog silicon VLSI devices or possibly future optical neural computers.     

Cardiac and vascular actions of sarafotoxin S6b and endothelin-1

Snake venom-derived sarafotoxin S6B (SRT) and porcine endothelium-derived endothelin-1 (ET) have striking structural similarities. In conscious, freely-moving rats, ET (0.67 nmol/kg) produced a transient tachycardia and fall in arterial blood pressure which was followed by a long-lasting increase in arterial pressure, bradycardia, decrease in cardiac output (CO) and marked increase in total peripheral resistance. In contrast, SRT (0.67 nmol/kg) produced only the sustained cardiovascular responses. The sustained cardiovascular effects of SRT or ET were similarly attenuated by nifedipine. SRT and ET (30 nM) produced vasoconstriction in the isolated perfused mesenteric vascular bed without initial vasodilation. SRT and ET had potent positive inotropic and negative chronotropic effects on isolated perfused hearts and induced toxic reactions including coronary vasospasm, arrhythmias, A-V block and ventricular fibrillation. In addition to SRT lacking the initial depressor response in vivo, several differences in the activities of the peptides were also observed. ET produced greater and longer-lasting actions than SRT in producing pressor and vasoconstrictor responses in all 3 preparations, and in its ability to induce toxic effects on the heart.     

Variability of entrainment of cohesive sediments in freshwater

Estimates of sediment entrainment are required for models of particle transport in lakes and estuaries but are difficult to make because of the multiplicity of factors affecting cohesiveness of surficial sediments. We present results of sediment resuspension studies performed in an annular flume calibrated with laser-Doppler velocimetry. In our experiments, using sediments collected from two sites in the R. Raisin which flows into L. Erie and from one site in the western basin of L. Erie near the mouth of the R. Raisin, we applied shear stresses at the sediment-water interface in steps from 2 to 12 dyne/cm². Percent water content at the surface of the sediments was either 77 or 74%, and trials were run with and without oxygenating the water overlying the sediments. Entrainment rates as a function of shear stress at the sediment-water interface were best described by a power-law relationship. All but 14% of the variability in the power law expression was due to shear stress and percent water content; the variability not accounted for was due to differences in particle size distributions, chemical properties, and biological activity in the sediments.     

人U_1和U_2snRNA基因定位缺失和取代突变

 用寡聚核苷酸诱导的定位突变法,将人U_1和U_2snRNA基因的5'-端调控区域的一段能与SV_(40)T抗原相结合的DNA删去,造成缺失突变,改变这段DNA核苷酸的排列顺序,造成取代突变。突变株用原位杂交法筛选,由限制性内切酶电泳图谱分析和DNA顺序测定得到证实。突变率约为5％。     

Clusters in social behaviour of female domestic cats (Felis silvestris catus) living in confinement

Associations between different agonistic and affiliative behavioural patterns of female domestic cats (Felis silvestris catus) were studied. In three groups of intact cats living in confinement frequencies of fourteen agonistic and affiliative behavioural patterns were recorded. The technique of factor analysis (Principal Components Analysis followed by varimax rotation on a dyads X behavioural patterns matrix) was used to detect clusters in these behavioural patterns. Five factors (or types of interindividual relationships) were extracted per group. They accounted collectively for at least 77% of the total variance present in the data. Although differences existed between groups with respect to behavioural patterns included in each factor, four clusters of behaviours could be discriminated: (I) social rubbing, lordosis and rolling in front of partner (sexual behaviour), (II) allogrooming, social sniffing, nosing, sniffing rear and treading (inspection-affiliative behaviour), (III) offensive behaviour and staring, and (IV) defensive behaviour and staring. The role of these clusters in group living is discussed.     

An efficient DDAB-mediated transfection of Drosophila S2 cells.

I have developed an efficient method for transfecting Drosophila S2 cells using DDAB, a cationic liposome reagent. The optimized DDAB method resulted in a 10 times or greater increase in transfection efficiency compared with the conventional calcium phosphate method which has been essentially the only way for transfecting S2 cells.     

重组水蛭素HV2的稳定性

重组水蛭素ＨＶ２是凝血酶的特异性抑制剂,是一种非常稳定的蛋白质。温度的升高（１００℃水浴）和ｐＨ（１─１３）的改变不影响其活力,在某些变性剂（８ｍｏｌ／Ｌ尿素、１％ＳＤＳ和６ｍｏｌ／Ｌ盐酸胍）存在的条件下也非常稳定,０．１ｍｏｌ／Ｌ的ＤＴＴ在７０℃时使其部分失活,只有ｐＨ和温度同时升高其活力才开始下降,ｐＨ１３、８０℃处理１５ｍｉｎ即完全失活,氨基酸组成和活性分析发现失活样品的Ｃｙｓ和Ｌｙｓ被破坏。重组水蛭素ＨＶ２含有一个结构紧密的Ｎ端核心区和一个无序的Ｃ端尾部。其Ｎ端的３个Ｌｙｓ－Ｘａａ键均不被胰蛋白酶水解;胃蛋白酶及糜蛋白酶消化后,分离所得片段,氨基酸组成分析发现Ｎ端核心区依然保持很高的抗凝血酶活性,继续消化２４ｈ,核心区不被进一步降解。