A study of antifungal antibiotic production by Streptomyces chattanoogensis MTCC 3423 using full factorial design

AIMS: The understanding of the dynamics of surface microbial colonization with concomitant monitoring of biofilm formation requires the development of biofilm reactors that enable direct and real-time evaluation under different hydrodynamic conditions. METHODS AND RESULTS: This work proposes and discusses a simple flow cell reactor that provides a means to monitoring biofilm growth by periodical removing biofilm-attached slides for off-line, both non-destructive and destructive biofilm analyses. This is managed without the stoppage of the flow, thus reducing the contamination and the disturbance of the biofilm development. With this flow cell, biofilm growth and respiratory activity can be easily followed, either in well-defined laboratory conditions or in an industrial environment. CONCLUSIONS, SIGNIFICANCE AND IMPACT OF THE STUDY: The reproducible and typical biofilm development curves obtained, validated this flow cell and confirmed its potential for different biofilm-related studies, which can include biocidal treatment.     

A cytosolic form of aminopeptidase P from Drosophila melanogaster: molecular cloning and characterization

Using a functional genomic approach, we have identified and characterized a cytosolic form of aminopeptidase P from Drosophila melanogaster. This study represents the first characterization of an insect aminopeptidase P. The complete sequence of a 12.5 kbp genomic clone from D. melanogaster showed the presence of a 1,839 bp ORF, encoding a protein of 613 amino acids with a calculated molecular mass of 68.5 kDa. The deduced amino acid sequence was 48% identical and 66% similar to rat and human cytosolic aminopeptidase P. Amino acids important for catalytic activity and the metal binding ligands were found to be conserved between Drosophila AP-P and its mammalian homologues. The recombinant enzyme expressed in Escherichia coli hydrolyzed the amino terminal Xaa-Pro bond of substance P and bradykinin, revealing its functional identity. Further enzyme characterization showed the enzyme to be a manganese-dependent metallopeptidase. Immunoblot analysis showed that DAP-P is located exclusively in the cytosol and is temporally regulated during Drosophila development. In the adult fly, the protein could be detected in gut, testis and ovary, with a high level of expression in brain.     

Inheritance of flower color in periwinkle: orange-red corolla and white eye

The commonly found flower colors in periwinkle (Catharanthus roseus)--pink, white, red-eyed, and pale pink center--are reported to be governed by the epistatic interaction between four genes--A, R, W, and I. The mode of inheritance of an uncommon flower color, orange-red corolla and white eye, was studied by crossing an accession possessing this corolla color with a white flowered variety (Nirmal). The phenotype of the F(1) plants and segregation data of F(2) and backcross generations suggested the involvement of two more interacting and independently inherited genes, one (proposed symbol E) determining the presence or absence of red eye and another (proposed symbol O) determining orange-red corolla.     

Function of cytokines within the TGF-beta superfamily as determined from transgenic and gene knockout studies in mice

Several major conceptual problems regarding specific in vivo functions of the TGF-beta family members remain the key focus of many researchers studying the biology of these secreted signaling molecules. More than 45 members of this family of growth factors have been identified and partially characterized for their molecular roles in numerous processes such as cell proliferation and differentiation, embryonic development, carcinogenesis, immune dysfunction, inflammation and wound healing. The high degree of similarity that exists at the structural level among the isoforms of these growth factors is accompanied by a significant overlap in function, as defined by many in vitro model systems and in vivo systems involving administration of exogenous ligand or of ligand-specific blocking antibodies. The ability to discern the critical functions of these molecules based on patterns of expression has also often been quite difficult. The evolution of more sophisticated functional genomics approaches has been recently instrumental in generating unique perspectives into the mechanisms governing the activity of the members of the TGF-beta family. The studies outlined in this review are significant in that they not only support working hypotheses regarding the activities of TGF-beta generated through extensive in vitro studies but also raise new questions regarding the role of each isoform in numerous processes. With the rapid advances in these approaches to probe activity in a more cell and time-dependent fashion, we will gain valuable insights for designing approaches for targeting the complex cellular pathways mediating their responses and will also help us develop novel therapies to treat disease processes.     

Analysis of DNA curvature distribution in mycobacterial promoters using theoretical models

In this paper, 125 different mycobacterial promoters are analyzed for their DNA curvature distribution using several di- and tri-nucleotide dependent models of DNA curvature. Different models give similar behavior and therefore qualitative validation of the results. Mycobacterial promoters resembling the E. coli sigma(70) type have almost 81% (85%) sequences having medium and high curvature profiles using dinucleotide-dependent models. Non-E. coli sigma(70) type mycobacterial promoters have comparatively higher percent of low curvature profiles. Very few extended -10 promoters have low curvature profiles. Mycobacterial promoters having A(n)T(m) (n+m > or =3) tract in the upstream region of -35 box and repeated in phase with each other have high curvature profiles. M. smegmatis promoters have high curvature profiles compared to M. tuberculosis promoters.     

Effect of nimesulide on acetic acid- and leukotriene-induced inflammatory bowel disease in rats

Inflammatory bowel disease (IBD) is a relapsing inflammation of intestine, which is mediated by release of inflammatory mediators. Both cyclo-oxygenase product prostaglandin (PGE2) and lipo-oxygenase product leukotriene (LTB4), may contribute to the pathogenesis of the inflammatory response. Nimesulide, a preferential COX-2 inhibitor was evaluated for its efficacy against experimental colitis in two different models (acetic acid- and LTB4-induced IBD) in rats. Inflammatory response was induced by intrarectal single administration of acetic acid or LTB4. Nimesulide (9 and 18 mg/kg, p.o.) significantly prevented development of inflammatory changes, decreased myeloperoxidase (MPO) activity, and also restored the altered contractility response of the isolated colon segment to KCl. The results suggested the involvement of both cyclo-oxygenase (COX) and lipo-oxygenase-mediated proinflammatory agents in colonic inflammatory process associated with IBD. Further, this study suggests that such therapeutic interventions may be of value in the treatment of IBD.     

A polarity complex of mPar-6 and atypical PKC binds,phosphorylates and regulates mammalian Lgl

The evolutionarily conserved proteins Par-6, atypical protein kinase C (aPKC), Cdc42 and Par-3 associate to regulate cell polarity and asymmetric cell division, but the downstream targets of this complex are largely unknown. Here we identify direct physiological interactions between mammalian aPKC, murine Par-6C (mPar-6C) and Mlgl, the mammalian orthologue of the Drosophila melanogaster tumour suppressor Lethal (2) giant larvae. In cultured cell lines and in mouse brain, aPKC, mPar-6C and Mlgl form a multiprotein complex in which Mlgl is targeted for phosphorylation on conserved serine residues. These phosphorylation sites are important for embryonic fibroblasts to polarize correctly in response to wounding and may regulate the ability of Mlgl to direct protein trafficking. Our data provide a direct physical and regulatory link between proteins of distinct polarity complexes, identify Mlgl as a functional substrate for aPKC in cell polarization and indicate that aPKC is directed to cell polarity substrates through a network of protein-protein interactions.     

Targeted elimination of peroxisome proliferator-activated receptor gamma in beta cells leads to abnormalities in islet mass without compromising glucose homeostasis

The nuclear hormone receptor peroxisome proliferator-activated receptor gamma (PPAR gamma) is an important regulator of lipid and glucose homeostasis and cellular differentiation. Studies of many cell types in vitro and in vivo have demonstrated that activation of PPAR gamma can reduce cellular proliferation. We show here that activation of PPAR gamma is sufficient to reduce the proliferation of cultured insulinoma cell lines. We created a model with mice in which the expression of the PPARG gene in beta cells was eliminated (beta gamma KO mice), and these mice were found to have significant islet hyperplasia on a chow diet. Interestingly, the normal expansion of beta-cell mass that occurs in control mice in response to high-fat feeding is markedly blunted in these animals. Despite this alteration in beta-cell mass, no effect on glucose homeostasis in beta gamma KO mice was noted. Additionally, while thiazolidinediones enhanced insulin secretion from cultured wild-type islets, administration of rosiglitazone to insulin-resistant control and beta gamma KO mice revealed that PPAR gamma in beta cells is not required for the antidiabetic actions of these compounds. These data demonstrate a critical physiological role for PPAR gamma function in beta-cell proliferation and also indicate that the mechanisms controlling beta-cell hyperplasia in obesity are different from those that regulate baseline cell mass in the islet.