Microbial transformation of sucrose and glucose to erythritol

Summary Two strains of osmophilic yeast which were isolated from honey-comb, produced good yields of erythritol as a main product. These strains were identified as Trichosporonoides sp., 150-5 and 331-1.From the fermentation studies with these strains using glucose and sucrose as substrate, strain 331-1 produced more erythritol as the sole polyhydric product,with trace quantities of glycerol, than strain 150-5.     

frizzled Gene expression and development of tissue polarity in the Drosophila wing

Almost every cell in the Drosophila pupal wing forms a single, distally pointing cuticular hair. The function of the frizzled (fz) gene is essential for the elaboration of the normal wing hair pattern. In the absence of fz function hairs develop, but they display an abnormal polarity. We have examined the developmental expression of the fi gene at the RNA level via in situ hybridization and at the protein level via Western blotting. We have found that fz is expressed in all regions of the epidermis before, during, and after the fz cold sensitive period. We have also found that fz function is not required for normal fi expression. We have further found that mutations in several other tissue polarity genes do not noticeably alter the expression or the modification state of the Fz protein. © 1994 Wiley-Liss, Inc.     

人──板系统最佳蹬伸动作的控制模型及数值分析

本文基于Hanavan模型和人体测量学参数,以人体各环节间的相对运动作为控制量,建立了人-板系统中起跳蹬伸动作的数学模型,给出了模型的数值计算方法,在此基础上给出了实现最佳蹬伸用力过程的计算实验途径与运动技术诊断方法。     

Fission yeast with DNA polymerase delta temperature-sensitive alleles exhibits cell division cycle phenotype.

DNA polymerases alpha and delta are essential enzymes believed to play critical roles in initiation and replication of chromosome DNA. In this study, we show that the genes for Schizosaccharomyces pombe (S.pombe) DNA polymerase alpha and delta (pol alpha+ and pol delta+) are essential for cell viability. Disruption of either the pol alpha+ or pol delta+ gene results in distinct terminal phenotypes. The S.pombe pol delta+ gene is able to complement the thermosensitive cdc2-2 allele of Saccharomyces cerevisiae (S.cerevisiae) at the restrictive temperature. By random mutagenesis in vitro, we generated three pol delta conditional lethal alleles. We replaced the wild type chromosomal copy of pol delta+ gene with the mutagenized sequence and characterized the thermosensitive alleles in vivo. All three thermosensitive mutants exhibit a typical cell division cycle (cdc) terminal phenotype similar to that of the disrupted pol delta+ gene. Flow cytometric analysis showed that at the nonpermissive temperature all three mutants were arrested in S phase of the cell cycle. The three S.pombe conditional pol delta alleles were recovered and sequenced. The mutations causing the thermosensitive phenotype are missense mutations. The altered amino acid residues are uniquely conserved among the known polymerase delta sequences.     

The vascular endothelial growth factor (VEGF) isoforms: differential deposition into the subepithelial extracellular matrix and bioactivity of extracellular matrix-bound VEGF.

Vascular endothelial growth factor (VEGF)mRNA undergoes alternative splicing events that generate four different homodimeric isoforms, VEGF121, VEGF165, VEGF189, or VEGF206. VEGF121 is a nonheparin-binding acidic protein, which is freely diffusible. The longer forms, VEGF189 or VEGF206, are highly basic proteins tightly bound to extracellular heparin-containing proteoglycans. VEGF165 has intermediate properties. To determine the localization of VEGF isoforms, transfected human embryonic kidney CEN4 cells expressing VEGF165, VEGF189, or VEGF206 were stained by immunofluorescence with a specific monoclonal antibody. The staining was found in patches and streaks suggestive of extracellular matrix (ECM). VEGF165 was observed largely in Golgi apparatus-like structures. Immunogold labeling of cells expressing VEGF189 or VEGF206 revealed that the staining was localized to the subepithelial ECM. VEGF associated with the ECM was bioactive, because endothelial cells cultured on ECM derived from cells expressing VEGF189 or VEGF206 were markedly stimulated to proliferate. In addition, ECM-bound VEGF can be released into a soluble and bioactive form by heparin or plasmin. ECM-bound VEGF189 and VEGF206 have molecular masses consistent with the intact polypeptides. The ECM may represent an important source of VEGF and angiogenic potential.     

-cyano-substituted analogoues of decarboxylated S-adenosylmethionine as enzyme activated, irreversible inhibitors of S-adenosylmethionine decarboxylase

A pair of -cyano analogues of decarboxylated S-adenosylmethionine (2a and 2b) were synthesized as potential enzyme activated, irreversible inhibitors of the[pyruvoyl enzyme S-adenosylmethionine decarboxylase (AdoMet-DC). Each of these analogues acts as an irreversible inactivator for ADoMet-DC from Escherichia coli (IC₅₀ values of 9 and 50 μM, respectively). These analogues also inactivate human AdoMet-DC, with K_I values of 246.6 and 7.2 μM, and k_inact values of 0.29 and 0.03 min⁻¹, respectively.     

Preparation of the pure diastereomeric forms of S- (5′-deoxy-5′-adenosyl)-1-ammonio-4-methylsulfonio-2- cyclopentene and their evaluation as irreversible inhibitors of S-adenosylmethionine decarboxylase from Escherichia coli

The conformationally restricted S-adenosylmethionine analogue AdoMac (S-(5′-deoxy-5′-adenosyl)-1-ammonio-4-methylsulfonio-2-cyclopentene has been shown to act as an enzyme activated, irreversible inhibitor of theEscherichia coli form of the enzyme S-adenosylmethionine decarboxylase. Inactivation of the enzyme is presumably initiated by formation of an imine linkage between the inhibitor and the terminal pyruvate of the enzyme, followed by base-catalyzed elimination of methylthioadenosine and generation of a latent electrophile. Removal of the driving force for the elimination of methylthioadenosine resulted in a reversibly binding inhibitor. Thus, the thioether analogue corresponding to AdoMac, and the corresponding dihydro derivative (H₂-AdoMac), reversibly inhibit the enzyme. AdoMac was resolved into its four pure diastereomeric forms, and each diastereomer was evaluated as an irreversible inhibitor of the enzyme. The K_I values for the individual diastereomers range between 3.83 and 39.6 μM, with the cis-1S,4R diastereomer being the most potent inhibitor. However, the k_inact values for the four diastereomers are not significantly different, suggesting that the binding of each diastereomer to the enzyme is configuration-dependent, while the subsequent inactivation likely proceeds through a single intermediate which is formed from each of the four diastereomers. Since each pure diastereomer represents a distinct conformational mimic exhibiting restricted sidechain rotation, the data suggests that these and related analogues may be useful as conformational probes for the catalytic site of AdoMet-DC.     

Integrating sample similarities into latent class analysis: a tree-structured shrinkage approach

This paper is concerned with using multivariate binary observations to estimate the probabilities of unobserved classes with scientific meanings. We focus on the setting where additional information about sample similarities is available and represented by a rooted weighted tree. Every leaf in the given tree contains multiple samples. Shorter distances over the tree between the leaves indicate a priori higher similarity in class probability vectors. We propose a novel data integrative extension to classical latent class models with tree-structured shrinkage. The proposed approach enables (1) borrowing of information across leaves, (2) estimating data-driven leaf groups with distinct vectors of class probabilities, and (3) individual-level probabilistic class assignment given the observed multivariate binary measurements. We derive and implement a scalable posterior inference algorithm in a variational Bayes framework. Extensive simulations show more accurate estimation of class probabilities than alternatives that suboptimally use the additional sample similarity information. A zoonotic infectious disease application is used to illustrate the proposed approach. The paper concludes by a brief discussion on model limitations and extensions.