Spatial expression dynamics of Men-9 delineate the third floral whorl in male and female flowers of dioecious Silene latifolia

Sex determination in Silene latifolia is controlled by heteromorphic sex chromosomes. Female flowers have five fused carpels and ten arrested stamen primordia. The male-determining Y chromosome overrides female development to suppress carpel formation and promote stamen development. The isolation and characterization of two S. latifoliaM ale en hanced cDNAs, Men-9a and Men-9b, which probably represent different alleles of a novel gene are reported here. Men-9a and Men-9b share 91.8% coding sequence nucleotide identity, yet only 85.4% amino acid identity. The Men-9 cDNAs are related to the previously reported MROS3 cDNA from S. latifolia. However, MROS3 is not present in the S. latifolia population used in these studies and the expression dynamics of Men-9a and Men-9b contrast dramatically with those reported for MROS3. Men-9 cDNAs are expressed primarily in anthers of young male flowers, with highest expression in 1–2 mm buds. Men-9 expression is also observed at a low level in female flowers. In situ hybridization analysis reveals two phases of Men-9 expression. The first phase is during a common stage of early stamen development in male and female flowers prior to stamen arrest in female flowers. The second phase of Men-9 expression is maximal in the epidermis and endothecium of Y chromosome- and Ustilago violacea-induced stamens; expression in male and female flowers extends to the epidermis of the staminal nectaries with strict boundaries at the second and fourth whorls. Men-9 gene expression therefore delineates the boundaries of the third floral whorl in S. latifolia flowers.     

Construction of an ∼2 Mb contig in the region around 80 cM of Arabidopsis thaliana chromosome 2

A method for construction of bacterial artificial chromosome (BAC) contigs from a yeast artifical chromosome (YAC) physical map is described. An ∼2 Mb contig, consisting of two large BAC contigs linked by a small YAC, has been assembled in the region around 80 cM of Arabidopsis thaliana chromosome 2. Clones from this contig will facilitate gene isolation in the region and can be used directly as substrates for DNA sequencing.     

水-有机溶剂两相体系中甲基单胞菌Z201催化丙烯环氧化的初步研究

Lanne于1987年提出了生物催化剂工程（Biocatalyst engimeering）和介质工程（Medium enineering）的概念^[1].有机相生物催化中溶剂的选择也是介质工程的内容之一。纯酶在有机相中的催化作用已有大量报道^[2],但对完整细胞研究甚少。本文以甲基单胞菌（Methylomonos）Z201完整细胞为生物催化剂,丙烯环氧化为指标反应,研究有机溶剂对活性的影响并对催化活性-溶剂疏水性进行了相关性分析。研究了水-十六烷两相体系中十六烷含量和搅拦速度对丙烯环氧化速度的影响和细胞的操作稳定性。     

Polyamine derivatives as inhibitors of trypanothione reductase and assessment of their trypanocidal activities

Trypanothione reductase (TR) occurs exclusively in trypanosomes and leishmania, which are the etiological agents of many diseases. TR plays a vital role in the antioxidant defenses of these parasites and inhibitors of TR have potential as antitrypanosomal agents. We describe the syntheses of several spermine and spermidine derivatives and the inhibiting effects of these compounds on T. cruzi TR. All of the inhibiting compounds displayed competitive inhibition of TR-mediated reduction of trypanothione disulfide. The three most effective compounds studied were N⁴,N⁸-bis(3-phenylpropyl)spermine (12), N⁴,N⁸-bis(2-naphthylmethyl)spermine (14), and N¹,N⁸-bis(2-naphthylmethyl)spermidine (21), with K_i values of 3.5, 5.5 and 9.5 μM, respectively. Compounds 12, 14, and 21 were found to be potent trypanocides in vitro with IC₅₀ values ranging from 0.19 to 0.83 μM against four T. brucei ssp. strains. However, these compounds did not prolong the lives of mice infected with trypanosomes. This work indicates that certain polyamine derivatives which target a unique pathway in Trypanosomatidae have potential as antitrypanosomal agents.     

Binding of vanadate to human erythrocyte ghosts and subsequent events

Spectroscopic techniques were used to investigate the interaction between vanadate and human erythrocyte ghosts. Direct evidence from ⁵¹V nuclear magnetic resonance (NMR) studies suggested that the monomeric and polymeric vanadate species may bind to the anion binding sites of band 3 protein of the erythrocyte membrane. The results of ⁵¹V NMR studies and the quenching effect of vanadate on the intrinsic fluorescence of the membrane proteins indicated that in the low concentration range of vanadate (<0.6 mm), monomeric vanadate binds mostly to the anion sites of band 3 protein with the dissociation constant close to 0.23 mm. The experiments of sulfhydryl content titration by the method of Ellman and residue sulfhydryl-labeled fluorescence spectroscopies clearly displayed that vanadate reacts directly with sulfhydryl groups. The appearance of the anisotropic election spin resonance (ESR) signal of vanadyl suggests that a small (c. 3%) amount of vanadate was reduced by sulfhydryl groups of membrane proteins. The fluidity and order of intact ghost membrane were reduced by the reaction with vanadate, as shown by the ESR studies employing the protein- and lipid-specific spin labels. It was concluded that although vanadates mainly bind to band 3 protein, a minor part of vanadate may oxidize the residue sulfhydryl groups of membrane proteins, and thus decrease the fluidity of erythrocyte membrane.     

Binding of antibodies against high and low molecular weight cytokeratin proteins in the human placenta with special reference to infarcts, proliferation and differentiation processes

Recent immunocytochemical studies have shown that placental villous trophoblasts contain the high molecular weight cytokeratin (CK) proteins 5/6 and 17. In the case of CK 17, trophoblastic immunostaining was positive in villi covered by fibrinoid. CKs 5/6 and 17 are expressed by hyperproliferative cells. The aim of this investigation was to examine the location of these CKs in placental infarcts, known to be demarcated by fibrinoid and hyperproliferative trophoblasts. The results were compared with those obtained by immunostaining against Ki-67, tenascin and α1-, α6- and β1- integrins, which are involved in cell proliferation, differentiation and regenerative processes. Furthermore, the expression of the single CKs 7, 8, 10, 13, 14, 18 and 19 was investigated by immunocytochemistry and immunoblotting. While low and high molecular weight CKs were present in villous and extravillous trophoblasts, only low molecular weight CKs were detected in vascular and extravascular placental smooth muscle cells. Placental infarcts revealed different immunoreactivities in the infarct margin and centre: high molecular CKs, tenascin, Ki-67 and oncofoetal fibronectin predominated in the infarct margin, low molecular CKs, fibrin and integrins in the centre. The expression of tenascin and a defined change in the expression of CK 17 indicates villous repair and hyperproliferative mechanisms in placental infarcts. This revised version was published online in November 2006 with corrections to the Cover Date.     

Purification, characterization, and properties of an aryl aldehyde oxidoreductase from Nocardia sp. strain NRRL 5646.

An aryl aldehyde oxidoreductase from Nocardia sp. strain NRRL 5646 was purified 196-fold by a combination of Mono-Q, Reactive Green 19 agarose affinity, and hydroxyapatite chromatographies. The purified enzyme runs as a single band of 140 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The molecular mass was estimated to be 163 +/- 3.8 kDa by gel filtration, indicating that this enzyme is a monomeric protein. The binding of the enzyme to Reactive Green 19 agarose was Mg2+ dependent. The binding capacity was estimated to be about 0.2 mg of Reactive Green agarose per ml in the presence of 10 mM MgCl2. This enzyme can catalyze the reduction of a wide range of aryl carboxylic acids, including substituted benzoic acids, phenyl-substituted aliphatic acids, heterocyclic carboxylic acids, and polyaromatic ring carboxylic acids, to produce the corresponding aldehydes. The Km values for benzoate, ATP, and NADPH were determined to be 645 +/- 75, 29.3 +/- 3.1, and 57.3 +/- 12.5 microM, respectively. The Vmax was determined to be 0.902 +/- 0.04 micromol/min/mg of protein. Km values for (S)-(+)-alpha-methyl-4-(2-methylpropyl)-benzeneacetic acid (ibuprofen) and its (R)-(-) isomer were determined to be 155 +/- 18 and 34.5 +/- 2.5 microM, respectively. The Vmax for the (S)-(+) and (R)-(-) isomers were 1.33 and 0.15 micromol/min/mg of protein, respectively. Anthranilic acid is a competitive inhibitor with benzoic acid as a substrate, with a Ki of 261 +/- 30 microM. The N-terminal and internal amino acid sequences of a 76-kDa peptide from limited alpha-chymotrypsin digestion were determined.     

Maximum activity of recombinant ribulose 1,5-bisphosphate carboxylase/oxygenase of Anabaena sp. strain CA requires the product of the rbcX gene.

Filamentous cyanobacteria of the genus Anabaena contain a unique open reading frame, rbcX, which is juxtaposed and cotranscribed with the genes (rbcL and rbcS) encoding form I ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO). Plasmid constructions containing the genes from Anabaena sp. strain CA were prepared, and expression studies in Escherichia coli indicated that the product of the rbcX gene mimicked the ability of chaperonin proteins to facilitate the proper folding of recombinant RubisCO proteins. The purified recombinant Anabaena sp. strain CA RubisCO, much like the RubisCO enzymes from other cyanobacteria, was shown not to undergo inhibition of activity during a time course experiment, and the properties of this chaperoned recombinant protein appear to be consistent with those of the enzyme isolated from the native organism.