Studies on the toxin of Aspergillus fumigatus. XVIII. Photooxidation of asp-hemolysin in the presence of various dyes and its relation to the site of hemolytic activity

The site of hemolytic activity of a toxin isolated from Aspergillus fumigatus designated Asp-hemolysin was determined by photooxidation techniques. The hemolytic activity of this toxin was strongly inhibited by photooxidation with methylene blue, rose bengal, riboflavin, or eosin G as a sensitizer, whereas crystal violet, hematoxylin, naphthol yellow S, bromothymol blue, methyl orange, and cresol red had no effect. pH dependence of the inactivation with methylene blue was observed in the narrow range of pH values from 7.0 to 8.0, like that of the inactivation with rose bengal or riboflavin. The histidine, cysteine, methionine, tryptophan, and tyrosine content of methylene blue-photooxidized Asp-hemolysin was significantly decreased, while other amino acids were not affected. The hemolytic activity of the toxin was lost more slowly than the histidine residue, being maintained at about 50% even at the time when the histidine residue was completely lost after 30 min. Photooxidation of Asp-hemolysin in the presence of rose bengal also caused a decrease in histidine, methionine, and threonine content. These findings suggest that residues of cysteine, methionine, threonine, tryptophan, and/or tyrosine but not histidine may play an important role through stereostructure in the manifestation of the hemolytic activity of Asp-hemolysin.     

Characterization of a cDNA clone encoding a basic protein, TP2, involved in chromatin condensation during spermiogenesis in the mouse

A cDNA clone encoding a small cysteine and serine-rich basic protein has been isolated from a mouse testis cDNA library. This cDNA clone encodes the mouse homologue of a protein involved in the initial phases of condensation of chromatin during spermiogenesis in rats, TP2, based on similarities in the sequence of the carboxyl terminus, composition, molecular weight, and electrophoretic mobility. Mouse TP2 can be divided into a highly basic domain comprising about one-third of the polypeptide chain at the carboxyl terminus and a much less basic domain comprising the remaining two-thirds at the amino terminus. The 5' end of the mouse TP2 mRNA contains two in-phase initiation codons both of which may be used generating two polypeptides which differ in length at the amino terminus. Southern blots demonstrate that there is a single copy of the TP2 gene in the mouse genome and Northern blots demonstrate that the polyadenylated TP2 mRNA is present at high and essentially equal levels in early and late haploid cells, and that it is virtually absent from meiotic cells.     

Preservation of sorghum plant portions harvested,processed and ensiled at ten stages of maturity

Two varieties of grain sorghum were harvested at 10 intervals from 35–189 days post planting. Leaf, stem and head portions were separated before being prepared for chemical analysis or ensiled for 30 days in 1-1 silos with or without preservatives. The taller variety (FS-1b) accumulated 60% more dry matter than ORO-T with advancing plant maturity, while whole plant crude protein content decreased from near 20 to less than 7% for both varieties. Dry matter ensiling loss (DMEL) was different (P < 0.05) for each plant portion, but was lower and less variable after the 77-day harvest. Immature leaves and heads resulted in the greatest average DMEL of 31 and 24%, respectively. Propionic acid decreased DMEL, while an ammonia solution was ineffective when compared to control leaf, stem and heads. The DMEL of leaves was influenced (P < 0.05) by a varietal × modulus of fineness interaction while the stem exhibited an interaction with plant maturity × modulus of fineness. Modulus of fineness was not associated with levels of organic acid production in silages, but plant maturity significantly influenced acetic, propionic and butyric acid production in heads. These data indicated that numerous combinations of silage preservation techniques affected DMEL of sorghum plant portions at different maturities.     

Extracellular matrix metabolism by chondrocytes 7. Evidence that L-glutamine is an essential amino acid for chondrocytes and other connective tissue cells

THe incorporation of [³H]glycine into acid-insoluble protein and of [³H]acetate into glysoaminoglycans by cultured chick chondrocytes was stimulated by the addition of L-glutamine to the incubation medium. The effect of exogenous L-glutamine on protein synthesis was studied further by examining changes in the sedimentation patterns on sucrose gardients of ribosomes isolated from chondrocytes incubated in presence and absence of L-glutamine. It was found that the absence of L-glutamine caused a disaggregation of poly-ribosomes that was reversed by the addition of this amino acid to the culture medium. No detectable glutamine synthetase activity could be measured in avian articular cartilage. These results indicate that L-glutamine is an essential amino acid for cartilage in that an extracellular supply of this amino acid is required for the maintenance of protein and glycosaminoglycan synthesis. A dependence on L-glutamine was also demonstrated for other avain connective tissues.     

Repetitive sequences of the sea urchin genome: Distribution of members of specific repetitive families

Three repetitive sequence families from the sea urchin genome were studied, each defined by homology with a specific cloned probe one to a few hundred nucleotides long. Recombinant λ-sea urchin DNA libraries were screened with these probes, and individual recombinants were selected that include genomic members of these families. Restriction mapping, gel blot, and kinetic analyses were carried out to determine the organization of each repeat family. Sequence elements belonging to the first of the three repeat families were found to be embedded in longer repeat sequences. These repeat sequences frequently occur in small clusters. Members of the second repeat family are also found in a long repetitive sequence environment, but these repeats usually occur singly in any given region of the DNA. The sequences of the third repeat are only 200 to 300 nucleotides long, and are generally terminated by single copy DNA, though a few examples were found associated with other repeats. These three repeat sequence families constitute sets of homologous sequence elements that relate distant regions of the DNA.     

Comparative tissue ascorbic acid studies in fishes

Comparative tissue ascorbic acid levels in four species of major carp viz., Labeo rohila, L. calbasu, Cirrhina tnrigala and Catla catla , were investigated. The ascorbic acid level was found to be the highest in the spleen in the four species studied (range 430–380 μg/g) followed by the anterior (adrenal) kidney, gonads, liver, renal kidney, brain and/or eye. Heart and blood had the lowest levels (range 26–18 μg/ml) amongst the tissues studied. Overall tissue ascorbic acid levels were the highest in L. rohita and the lowest in C. mrigala . Investigation on seasonal variations in blood and kidney ascorbic acid levels of Notopterus notopterus revealed peak levels in spring (February-April) and the lowest levels in the postspawning period (August-September).     

Relation between D-glucose and L- and D-alanine in the initiation of germination of Bacillus subtilis spore

The rate of L-alanine-initiated germination of Bacillus subtilis spore was measured by both loss of heat resistance and loss of turbidity, and the effect of glucose on the germination response to a wide range of concentrations of the germinant was analyzed in the presence and absence of D-alanine, an inhibitor. Glucose stimulated L-alanine germination by means of a cooperative effect: glucose increased the affinity of L-alanine by about 3-fold and the rate of germination by about 1.3-fold. However, glucose had little effect on the binding affinity of D-alanine. The apparent binding constant of L-alanine to the spore, which was determined by the next measurable event in the trigger reaction, was 1.2 X 10(-5), that of D-alanine was 6 X 10(-6), and that of glucose was 5 X 10(-5). The relation between the binding site for glucose and those for L- and D-alanine on the spore is discussed. Effect of glucose analogs was also examined.     

Acetone-regulated synthesis and degradation of cytochrome P450E1 and cytochrome P4502B1 in rat liver [corrected

The regulation of CYP2E1 and 2B1 was studied by following mRNA levels, catalytic activities and the subcellular distribution of the apoproteins in rat liver 0, 6, 12, 24, 48 and 96 h after a single intragastric dose of acetone. No changes were observed in hepatic CYP2E1 mRNA levels at any time after acetone treatment, whereas rapid rises were observed in the microsomal amount of CYP2E1 protein and CYP2E1-catalyzed 4-nitrophenol hydroxylase and carbon-tetrachloride-initiated lipid-peroxidation activities. However, CYP2E1-dependent catalytic activities declined much faster than the immunodetectable CYP2E1 protein, suggesting that this cytochrome P-450 is inactivated prior to degradation. Similar results were seen in primary hepatocyte cultures. By contrast, concomitant changes in levels of CYP2B1 and CYP2B1-dependent O-depentylation of pentoxyresorufin were observed in the same microsomal preparations. Investigation of the degradative mechanism of both CYP2E1 and CYP2B1 by immunoquantitation of the proteins in lysosomes and by immunohistochemistry indicated their degradation via an autophagic-lysosomal pathway. The data suggest that CYP2E1 is acutely inactivated in the endoplasmic reticulum and that degradation of this isozyme occurs, at least in part, by the lysosomal route. By contrast, CYP2B1 is principally controlled at the level of synthesis.