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.     

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.     

Isolation and screening of potential actinobacteria for rapid composting of rice straw

Rice straw is produced as a by-product from rice cultivation, which is composed largely of lignocellulosic materials amenable to general biodegradation. Lignocellulolytic actinobacteria can be used as a potential agent for rapid composting of bulky rice straw. Twenty-five actinobacteria isolates were isolated from various in situ and in vitro rice straw compost sources. Isolates A2, A4, A7, A9 and A24 were selected through enzymatic degradation of starch, cellulose and lignin followed by the screening for their adaptability on rice straw powder amended media. The best adapted isolate (A7) was identified as Micromonospora carbonacea. It was able to degrade cellulose, hemicelluloses and carbon significantly (P ≤ 0.05) over the control. C/N ratio was reduced to 18.1 from an initial value of 29.3 in 6 weeks of composting thus having the potential to be used in large scale composting of rice straw.     

Alanine metabolism in the perfused rat liver. Studies with (15)N.

We have utilized [(15)N]alanine or (15)NH(3) as metabolic tracers in order to identify sources of nitrogen for hepatic ureagenesis in a liver perfusion system. Studies were done in the presence and absence of physiologic concentrations of portal venous ammonia in order to test the hypothesis that, when the NH(4)(+):aspartate ratio is >1, increased hepatic proteolysis provides cytoplasmic aspartate in order to support ureagenesis. When 1 mm [(15)N]alanine was the sole nitrogen source, the amino group was incorporated into both nitrogens of urea and both nitrogens of glutamine. However, when studies were done with 1 mm alanine and 0.3 mm NH(4)Cl, alanine failed to provide aspartate at a rate that would have detoxified all administered ammonia. Under these circumstances, the presence of ammonia at a physiologic concentration stimulated hepatic proteolysis. In perfusions with alanine alone, approximately 400 nmol of nitrogen/min/g liver was needed to satisfy the balance between nitrogen intake and nitrogen output. When the model included alanine and NH(4)Cl, 1000 nmol of nitrogen/min/g liver were formed from an intra-hepatic source, presumably proteolysis. In this manner, the internal pool provided the cytoplasmic aspartate that allowed the liver to dispose of mitochondrial carbamyl phosphate that was rapidly produced from external ammonia. This information may be relevant to those clinical situations (renal failure, cirrhosis, starvation, low protein diet, and malignancy) when portal venous NH(4)(+) greatly exceeds the concentration of aspartate. Under these circumstances, the liver must summon internal pools of protein in order to accommodate the ammonia burden.     

Identification of a GM1-Binding Protein on the Surface of Murine Neuroblastoma Cells

S20Y murine neuroblastoma cells appear to express a protein component(s) able to adhere specifically to the oligosaccharide portion of GM1 (oligo-GM1). To identify proteins with which the oligo-GM1 becomes closely associated, a radiolabeled (125I), photoactivatable derivative of oligo-GM1 was prepared. This was accomplished by reductive amination of the glucosyl moiety of oligo-GM1 to 1-deoxy-1-aminoglucitol, followed by reaction of the amine with sulfosuccinimidyl 2-(p-azidosalicylamido)ethyl-1,3'-dithiopropionate (SASD). Crosslinking studies using the photoactivatable probe indicated that it came in close proximity to a protein with an apparent molecular mass of approximately 71 kDa. In competition experiments, as little as a 10-fold molar excess of oligo-GM1 resulted in a selective reduction in labeling of this protein; preincubation with a 200-fold molar excess of siayllactose was necessary to observe the same change in the labeling pattern, lending additional support to the hypothesis that the approximately 71-kDa protein specifically associates with oligo-GM1. Cell surface location of the oligo-GM1 binding protein was confirmed using subcellular fractionation and morphological analyses.     

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.     

Circulating immune complexes in the pathogenesis of recurrent erysipelas

The dynamics of circulating immune complexes (CIC) in comparison with the level of SH-groups of serum deproteinate and other characteristics of cell-mediated and humoral immunity (the reaction of the inhibition of antibodies, the levels of T-cells and their main subpopulations) was studied in 103 erysipelas patients and in 46 persons having had the disease at the acute period of this infection and at the periods between relapses. The elevated levels of CIC and SH-groups of serum deproteinate were found to be directly correlated with the inhibition index. The study showed that, as a rule, in patients with the elevated level of CIC the frequently relapsing form of erysipelas, accompanied by the formation of relative hypersuppressor-type secondary immunodeficiency and by a decrease in the functional activity of dermal macrophages, was observed.