Dimorphism inBenjaminiella poitrasii: cell wall chemistry of parent and two stable yeast mutants

In the dimorphic zygomycetous fungusBenjaminiella poitrasii, the cell wall compositions of mycelial phase (M), yeast phase (Y) and its yeast form mutants (Y-2 and Y-5) were studied. Chitosan was abundant in M-phase (26.6%) whereas lesser amounts were present in Y-phase (17.3%) and in mutants Y-2 (19.6%) or Y-5 (17.3%). Although chitin was present as a smaller fraction of the total glucosaminoglycan in each of different cell wall preparations, it was almost 3 times more prevalent in M-phase than the Y-phase cells. Cross-linking studies among the various cell wall components inB. poitrasii, suggest linkages among mannans and proteins and glucans and glucosaminoglycans.NCL Communication No. 5111.     

An experimental study of a modified turbidostat

Summary The efficacy of a modified turbidostat scheme for control of a continuous fermentor supporting substrate - inhibited growth of a methylotroph, L3, was experimentally examined. The control was based on continuous measure of optical density of fermentation broth. The experimental results illustrate the feasibility of the control scheme for effective startup as well as stabilization of a continuous fermentor under the influence of a load disturbance.     

Carbodithioate MeOBDCG for decreasing intracellular cadmium deposits in rats of different ages

The efficiency of chelating agents to remove aged intracellular deposits of cadmium in young and older rats was studied. The administration of the chelating agent sodiumN-(4-methoxybenzyl)-D-glucamine-N-carbodithioate monohydrate (MeOBDCG) 2 wk after a single intraperitoneal 115m Cd administration reduced the whole body, liver, and kidney retention in suckling rats to about 63, 42, and 71 percent and in older rats to 39, 17 and 76 percent of values obtained in respective controls. Chelation therapy was generally more effective in older than younger rats and the age-related effect was most pronounced in the liver. These results indicate that specific features of young organisms may significantly alter the effect of chelation treatment.     

The origins of specificity in polyketide synthase protein interactions

Polyketides, a diverse group of heteropolymers with antibiotic and antitumor properties, are assembled in bacteria by multiprotein chains of modular polyketide synthase (PKS) proteins. Specific protein-protein interactions determine the order of proteins within a multiprotein chain, and thereby the order in which chemically distinct monomers are added to the growing polyketide product. Here we investigate the evolutionary and molecular origins of protein interaction specificity. We focus on the short, conserved N- and C-terminal docking domains that mediate interactions between modular PKS proteins. Our computational analysis, which combines protein sequence data with experimental protein interaction data, reveals a hierarchical interaction specificity code. PKS docking domains are descended from a single ancestral interacting pair, but have split into three phylogenetic classes that are mutually noninteracting. Specificity within one such compatibility class is determined by a few key residues, which can be used to define compatibility subclasses. We identify these residues using a novel, highly sensitive co-evolution detection algorithm called CRoSS (correlated residues of statistical significance). The residue pairs selected by CRoSS are involved in direct physical interactions in a docked-domain NMR structure. A single PKS system can use docking domain pairs from multiple classes, as well as domain pairs from multiple subclasses of any given class. The termini of individual proteins are frequently shuffled, but docking domain pairs straddling two interacting proteins are linked as an evolutionary module. The hierarchical and modular organization of the specificity code is intimately related to the processes by which bacteria generate new PKS pathways.     

Synthesis, spectroscopic and biological aspects of iron(II) complexes

Five novel coordinated complexes of iron(II) with ciprofloxacin and neutral bidentate ligands have been prepared and characterized using elemental analyses, magnetic measurements, IR spectra, UV-VIS spectral, thermogravimetric analyses, 1H-NMR and 13C-NMR. The antimicrobial activity of the individual ligands, metal salt and metal complexes with respect to Bacillus subtilis, Escherichia coli, Bacillus cereus, Staphylococcus aureus, Salmonella typhi, Serratia marcescens, Aspergillus niger, Aspergillus flavus and Lasiodiplodia theobromae were evaluated by the agar-plate technique in comparison to reference standard drugs (ofloxacin, levofloxacin and fluconozole). Binding of the complexes to DNA was studied and is discussed.     

Genome Sequence of a Novel Actinophage PIS136 Isolated from a Strain of Saccharomonospora sp

A wide-host-range bacteriophage (phage) PIS136 was isolated from PA136, a strain of Saccharomonospora belonging to the group actinomycetes. Here, we present the genome sequence of the PIS136 phage, which is 94,870 bp long and contains 132 putative coding sequences and one tRNA gene. An IS element-like region with two genes for putative transposases was identified in the genome. The presence of IS element-like sequences suggests that PIS136 is still under active evolution.