Antitrypanosomal action of cis-diamminedichloroplatinum (II) analogs

The present report deals with the alterations produced by cis-diamminedichloroplatinum (II) (DDP), and 2 of its analogs: cis-Pt(II)(tranylcypromine)2Cl2 and cis-Pt(II)(benzothiazole)2Cl2 in cultured epimastigote forms of Trypanosoma cruzi. Studies have been performed at the ultrastructural level and the inhibitory effect of these complexes on macromolecule synthesis, evaluated by 3H-thymidine, 3H-uridine, and 3H-leucine incorporation, has been investigated. DDP at concentrations of 50 and 100 micrograms/ml does not inhibit significantly the incorporation of radioactive precursors, but a clear decrease was observed with the 2 analogs. Eight hours of treatment at a concentration of 10 micrograms/ml rendered in all 3 cases an increase in autophagic vacuoles and lipids as well as an abnormal condensation of the nucleus chromatin.     

Extramacrochaetae,a trans-acting gene of the achaete-scute complex of Drosophila involved in cell communication

Summary Phenotypic analyses of genetic combinations involving the gene extramacrochaetae (emc) reveal its participation in the differentiation of both sensory elements and wing veins. The study of near-amorphic alleles of emc in mitotitc recombination clones indicates that it also affects cell proliferation. These clones show abnormal sizes, shapes and spatial distribution. They differentiate extra sensory elements as well as extra veins. A gain of function mutation in the gene causes opposite phenotypes in both differentiation systems. The effects of the mutant on proliferation and patterning are consistent with the emc gene being involved in the transfer of information between neighbouring cells, which leads to the spatial expression of the achaetescute gene complex and genes involved in vein formation.     

Transport of ethanol in baker’s yeast

Ethanol is transported into various strains of baker's yeast by simple diffusion (no effect of inhibitors and a linear concentration dependence of the initial rate of uptake and final distribution in cells). It distributes itself in 96.6 +/- 16.2% of intracellular water.     

Management of a harem breeding colony of rhesus monkeys to reduce trauma-related morbidity and mortality

A management procedure was developed for a harem breeding colony of rhesus monkeys to reduce trauma-related injuries and deaths resulting from the periodic removal of pregnant monkeys for research and their subsequent return to the population. Lower morbidity and mortality rates, a reduced mean conception interval, and a higher mean conception rate occurred when monkeys were maintained in permanent harems to which returning females were reintroduced compared to new social groups formed from aggregates of unfamiliar animals.     

Evidence for Plasmid Linkage of Raffinose Utilization and Associated alpha-Galactosidase and Sucrose Hydrolase Activity in Pediococcus pentosaceus

The ability to ferment the trisaccharide raffinose was linked with the presence of plasmid DNA in three strains of Pediococcus pentosaceus. Parental strains showed associated inducible alpha-galactosidase and sucrose hydrolase activities when grown in alpha-galactosides and sucrose, respectively. Derivative strains of PPE1.0, PPE2.0, and PPE5.0, which had lost 30-, 28-, and 23-megadalton plasmids, respectively, had no alpha-galactosidase or sucrose hydrolase activity.     

The anthranilate aggregate of Escherichia coli: kinetics of inhibition by tryptophan of phosphoribosyltransferase

The kinetic mechanism of the phosphoribosyltransferase reaction is shown to be rapid equilibrium random bi bi with an enzyme-anthranilate-pyrophosphate abortive complex. We present a rate equation that not only predicts the observed kinetic patterns but also accommodates the fact that feedback inhibition is partial, even though tryptophan (Ki = 0.5 microM) and phosphoribosylpyrophosphate (Km = 50 microM) are competitive. Neither ligand completely abolishes the effect of the other. Instead, the binding of one ligand leads to a mutual elevation in the dissociation constant of the opposing ligand by a factor of two to three. Tryptophan inhibition is noncompetitive with respect to anthranilate (Km = 0.58 microM) and does not diminish the rate of interconversion of ternary complexes. Tryptophan cooperativity, with respect to the inhibition of phosphoribosyltransferase, conforms to the concerted Monod-Wyman-Changeux formulation (kinetic Hill coefficient = 2), whereas tryptophan as an inhibitor of anthranilate synthase more closely conforms to a Koshland model of sequential cooperativity with a kinetic Hill coefficient of 1.4. The aggregate contains only one class of tryptophan sites. Thus the first tryptophan molecule bound to the aggregate maximally inhibits both phosphoribosyltransferase active centers and one of the two anthranilate synthase catalytic sites. The remaining anthranilate synthase subunit thereupon is converted into a form with less (but not zero) affinity for chorismate and a greater affinity for a second molecule of tryptophan.     

The steroids and fatty acids of the basidiomycete Scleroderma polyrhizum

The fruit bodies of the Basidiomycete Scleroderma polyrhizum have been shown to contain the steroids ergosta-4,6,8(14) 22-tetraen-3-one and 5α,8α-epidoxyergosta-6,22-dien-3β-ol and also palmitic and oleic acids.