Comparative analysis of respiratory activity in the wild type strain of <Emphasis Type="Italic">Neurospora crassa</Emphasis> and its photoreceptor complex mutants

Cell respiratory activity of protoplasts obtained from the wild type of Neurospora crassa and photoreceptor complex WCC—white collar 1 (wc-1) and white collar 2 (wc-2)—mutants of Neurospora crassa strains was investigated. Respiration inhibition by KCN in the presence of 25 mM succinate was similar in all strains and did not exceed 83–85% against control. The significant induction of KCN-resistant respiratory pathway occurred under 1% glucose oxidation in wc-1 and wc-2 mutants if compared with the wild type strains. The inhibitors of the main (cytochrome) pathway of electron transfer in mitochondria—1 mM KCN and antimycin A (4 μg/ml)—blocked the respiration rate of the protoplasts from N. crassa wild type by 75%, while the cell respiration of wc-1 and wc-2 strains was suppressed by approximately 50%. The specific inhibitor of alternative oxidase—10 mM salicylhydroxamic acid (SHAM)—in combination with the blockers of mitochondrial electron transfer chain caused the total suppression of respiratory activity of protoplasts in all studied strains. It is supposed that an increase of KCN-resistance in WCC mutants under glucose oxidation is connected with alternative oxidase activation as the result of failure in reception and signal transduction of active oxygen species.     

Initial Commitment to Pre-Exposure Prophylaxis and Circumcision for HIV Prevention amongst Indian Truck Drivers

Studies of HIV prevention interventions such as pre-exposure prophylaxis (PREP) and circumcision in India are limited. The present study sought to investigate Indian truck-drivers initial commitment to PREP and circumcision utilizing the AIDS Risk Reduction Model. Ninety truck-drivers completed an in-depth qualitative interview and provided a blood sample for HIV and HSV-2 testing. Truck-drivers exhibited low levels of initial commitment towards PREP and even lower for circumcision. However, potential leverage points for increasing commitment were realized in fear of infecting family rather than self, self-perceptions of risk, and for PREP focusing on cultural beliefs towards medication and physicians. Cost was a major barrier to both HIV prevention interventions. Despite these barriers, our findings suggest that the ARRM may be useful in identifying several leverage points that may be used by peers, health care providers and public health field workers to enhance initial commitment to novel HIV prevention interventions in India.     

Decreased virulence in stable,acapsular mutants ofCryptococcus neoformans

Six acapsular strains ofCryptococcus neoformans obtained by chemical mutagenesis failed to produce a capsulein vivo and were avirulent in mice following high dose intramuscular, intraperitoneal or intravenous inoculation. Peritoneal granulomas were observed in all animals inoculated with the acapsular mutants. These granulomas were characterized by a large central mass consisting of intact, degenerating and necrotic yeast cells. This was surrounded by concentric layers of a broad band of histiocytes, a narrow band of fibroblasts, and around the periphery, a mass of lymphocytes and plasma cells. These isolates did not revert to an encapsulated or virulent state after more than a year of subculturing or 18 passages through mice.     

High performance liquid chromatography,chemical laboratory practice: By Heinz Engelhardt. Springer-Verlag,New York/Berlin, 1979. 248 pp. $29.80

A gel filtration method has been developed for the complete removal of sodium dodecyl sulfate (SDS) from proteins and peptides. The protein or peptide (20 μg–10 mg) containing SDS (up to 30–60 mg) is dissolved in a mixture of propionic acid, formic acid, and water (2:1:2, $\text{v}\text{v}$). Under these conditions, protein-SDS (or peptide-SDS) complexes, as well as SDS micelles, are dissociated. Subsequently, protein and SDS can be separated on a small Sephadex G-25 superfine column. The recovery of protein is typically 90% or more.     

Acetate production from lactate and glucose fermentation by Gluconobacter oxydans

Summary The production of acetate from the fermentation of lactate by Gluconobacter oxydans was studied. Batch experiments showed that glucose was the preferred substrate compared to lactate. A fed-batch culture was fed with a mixture of glucose and lactate followed by periodic addition of lactate. The maximum productivity of acetate was 0.16 g/l h but this value decreased during the fedbatch culture due to growth inhibition by acetate.     

Limited proteolysis of human erythrocyte Ca2+-ATPase in membrane-bound form. Identification of calmodulin-binding fragments

Water-soluble and membrane-bound calmodulin-binding polypeptides formed upon limited proteolysis of erythrocyte ghosts were isolated by means of affinity chromatography. Immune blotting revealed that all isolated fragments originated from Ca2+-ATPase. Among the fragments obtained those having formed an acylphosphate intermediate were identified. The N-terminal residue of purified intact Ca2+-ATPase was shown to be blocked (probably acylated).     

Reactivity and binding of benzo(a)pyrene diol epoxide to poly(dG-dC).(dG-dC) and poly(dG-m5dC).(dG-m5dC) in the B and Z forms

The physical and covalent binding of the carcinogen benzo(a)pyrene-7,8-diol-9,10-oxide (BaPDE) to poly(dG-dC).(dG-dC) and poly(dG-m5dC).(dG-m5dC) in the B and Z forms were studied utilizing absorbance, fluorescence and linear dichroism techniques. In the case of poly(dG-dC).(dG-dC) the decrease in the covalent binding of BaPDE with increasing NaCl concentration (0.1-4 M) as the B form is transformed to the Z form is attributed to the effects of high ionic strengths on the reactivity and physical binding of BaPDE to the polynucleotides; these effects tend to obscure differences in reactivities with the B and Z forms of the nucleic acids. In the case of poly(dG-m5dC).(dG-m5dC) the B-to-Z transition is induced at low ionic strength (2 mM NaCl + 10 microM Co(NH3)6Cl3) and the covalent binding is found to be 2-3-times lower to the Z form than to the B form. Physical binding of BaPDE by intercalation, which precedes the covalent binding reaction, is significantly lower in the Z form than in the B form, thus accounting, in part, for the lower covalent binding. The linear dichroism characteristics of BaPDE covalently bound to the Z and B forms of poly(dG-m5dC).(dG-m5dC) are consistent with nonintercalative, probably external conformations of the aromatic pyrenyl residues.