Inhibition of protein and lipid synthesis in muscle by 2,4-dinitrofluorobenzene, an inhibitor of creatine phosphokinase

A photoaffinity label, 4-azidobenzoyltrimethionine has been synthesized. It competitively inhibits trimethionine uptake in the yeast C. albicans. Upon UV irradiation it irreversibly and specifically blocks oligopeptide uptake. These results give the first example of photoinhibition of peptide uptake in yeast.     

Structure-activity relations of the molluscan neuropeptide FMRFamide on some molluscan muscles

Analogs of the molluscan neuropeptide FMRFamide were tested on four different molluscan muscle preparations which show qualitatively different responses to the peptide; the structure-activity relations are basically similar, but not identical. The C-terminal amide and the Arg³ residue are critical for FMRFamide-like activity on all four preparations. In contrast, analogs extended at the N-terminal or with conservative substitutions for the Phe¹ or Met² residue are approximately equipotent to FMRFamide. These structural requirements parallel those for the C-terminal tetrapeptide amide of gastrin.     

Development and evaluation of a starter culture for the industrial production of gari

Gari starter cultures (Gastat) were developed by mixing pure single strains of the organisms that ferment cassava. They were propagated and maintained as granules on dried cocoyam slurry. The cultures were tested for fermentative and acid-producing activity. The acidity produced at 30°C varied from 0.07% to 0.85% lactic acid with maximum levels occurring after 48 h. High levels of reducing sugar were produced during the first 24 h. The amounts produced were about 50% more than those from the self-inoculated cassava. The quality of the gari produced by the starter cultures was good and well accepted. The texture was similar to that produced by natural fermentation. These results highlight the possibility of using starter cultures in the large-scale production of gari.     

Asymmetric synthesis of (S)-ethyl-4-chloro-3-hydroxybutanoate using Candida parapsilosis ATCC 7330

Asymmetric reduction of ethyl-4-chloro-3-oxobutanoate to (S)-ethyl-4-chloro-3-hydroxybutanoate in aqueous medium by resting cells of Candida parapsilosis ATCC 7330 was optimized. The influence of culture parameters (inoculum size, inoculum age and biocatalyst harvest time) and reaction parameters (co-substrate, resting cell, pH and substrate concentrations) on the asymmetric reduction were studied. It was found that these parameters significantly influenced the rate of the asymmetric reduction. Under the optimum conditions, the final concentration of (S)-ethyl-4-chloro-3-hydroxybutanoate, enantiomeric excess and the isolated yield of (S)-ethyl-4-chloro-3-hydroxybutanoate were 1.38 M (230 g/l), >99 and 95%, respectively. The space time yield was 115 mmol/lh, which is significantly higher than other whole cell biocatalysts reported so far.     

Hemoglobin Dallas (alpha 97(G4)Asn-->Lys): functional characterization of a high oxygen affinity natural mutant.

Hemoglobin Dallas, an alpha-chain variant with a substitution of lysine for asparagine at position 97(G4), was found to have increased oxygen affinity (p1/2 = 1 mmHg at pH 7.3 and 20 degrees C), diminished cooperativity (n, the Hill coefficient = 1.7) and reduced Bohr effect (about 50%). Addition of allosteric effectors (such as 2,3-diphosphoglycerate, inositol hexakisphosphate and bezafibrate) led to a decrease in oxygen affinity and increase in cooperative energy. Kinetic studies at pH 7.0 and 20 degrees C revealed that (i), the overall rate of oxygen dissociation is 1.4-fold slower than that for HbA and (ii), the carbon monoxide dissociation rate is unaffected. The abnormal properties of this hemoglobin variant can be attributed to a more 'relaxed' T-state.     

Binding of lipoproteins to inert materials revisited with computer-assisted analysis

A number of studies conducted in the last decade showed that saturable ('specific') binding, by itself, does not necessarily imply biological significance. That is, biological ligands were shown to bind to inert materials as well as to biological receptors in a saturable manner. In these studies specific binding was operationally defined as binding that was displaceable by excess concentrations of unlabeled ligand. This method of measuring specific binding is now no longer considered optimal. To investigate whether optimal (computer-assisted) techniques of measuring specific binding--namely, nonlinear least-squares curve fitting of total binding data, with mathematical separation of the total binding into its various components--might ensure biological significance of measured specific binding, we studied the binding of high-density lipoproteins (HDL3) to tissue culture dishes as an example of binding without biological significance. This binding closely followed the paradigm of a ligand interacting with a class of homogeneous, saturable sites and with a class of relatively unsaturable sites, just as it would have if the HDL3 were interacting with an unpurified biological receptor. This finding indicates that computer-assisted analysis, while most accurately describing binding data, nevertheless does not ensure that measured specific binding has biological significance. Saturability is such a nonselective feature of equilibrium binding data that it should probably no longer be considered one of the criteria for deciding whether or not a defined binding site is a receptor.     

Round robin investigation of methods for recovering human enteric viruses from sludge

To select a tentative standard method for detection of viruses in sludge the American Society for Testing and Materials D19:24:04:04 Subcommittee Task Group initiated round robin comparative testing of two procedures that, after initial screening of several methodologies, were found to meet the basic criteria considered essential by the task group. Eight task group member laboratories agreed to perform round robin testing of the two candidate methods, namely, The Environmental Protection Agency or low pH-AlCl3 method and the Glass or sonication-extraction method. Five different types of sludge were tested. For each particular type of sludge, a single laboratory was designated to collect the sludge in a single sampling, make samples, and ship it to the participating laboratories. In most cases, participating laboratories completed all the tests within 48 h of sample arrival. To establish the reproducibility of the methods, each laboratory tested each sludge sample in triplicate for the two candidate virus methods. Each processed sludge sample was quantitatively assayed for viruses by the procedures of each individual round robin laboratory. To attain a more uniform standard of comparison, a sample of each processed sample from all laboratories was reassayed with one cell line and passage number by a single laboratory (Environmental Protection Agency Environmental Monitoring and Support Laboratory, Cincinnati, Ohio). When the data were statistically analyzed, the Environmental Protection Agency method was found to yield slightly higher virus recoveries for all sludge types, except the dewatered sludge. The precisions of both methods were not significantly different.(ABSTRACT TRUNCATED AT 250 WORDS)     

The study of X-rays and TCDD effects on satellite associations may suggest a simple model for application in environmental mutagenesis

Summary Satellite associations were used as parameters to test nucleolar organizer activity. Assuming that toxic and/or mutagenic agents may affect the ribosomal genes, satellite associations in human lymphocytes were analysed following exposure to X-rays and compared with the satellite association pattern of subjects exposed to TCDD. A significant decrease in the satellite association frequency in D group chromosomes was found both in irradiated lymphocytes and in subjects exposed to Dioxin. The findings seem to be in accordance with the hypothesis based on random damage of functional nucleolar organizing regions.