Analysis,characterization and diagnostic use of circulating filarial antigen in bancroftian filariasis

Sodium dodecyl sulphate-polyacrylamide gel electrophoresis of circulating filarial antigen fraction-2 isolated from plasma of microfilaraemic patients withWuchereria bancrofti infection has shown 21 bands with molecular weights ranging from 12 to 120 kDa. The gel (12 cm) was sliced at an interval of one cm and the eluates of all the gel slicesviz., CFA2-1 to CFA2-12 showed the presence of filarial antigen by sandwich enzyme-linked immunosorbent assay. The low molecular weight circulating filarial antigen fractions were found to share a common epitope withWuchereria bancrofti microfilariae excretory-secretory antigen and urinary filarial antigen. The 3 antigen fractions CFA2-1, CFA2-9 and CFA2-12 showed higher sensitivity in detecting filarial immunoglobulin M antibodies than immunoglobulin G antibodies. However CFA2-9 fraction was found useful in serological differentiation of microfilaraemics from those with disease manifestations when filarial immunoglobulin G antibodies were detected. The antigenic epitope of CFA2-1 appears to be a carbohydrate, whereas CFA2-9 appears to be protein in nature.     

Correlation between stability of a protein and its dipeptide composition: a novel approach for predicting in vivo stability of a protein from its primary sequence

Statistical analysis of 12 unstable and 32 stable proteins revealed that there are certain dipeptides, the occurrence of which is significantly different in the unstable proteins compared with those in the stable ones. Based on the impact of these dipeptides on the unstable proteins over the stable ones, a weight value of instability is assigned to each of the dipeptides. For a given protein the summation of these weight values normalized to the length of its sequence helps to distinguish between unstable and stable proteins. Results suggest that the in vivo instability of proteins is possibly determined by the order of certain amino acids in its sequence. An attempt is made to correlate metabolic stability of proteins with features of their primary sequence where weight values of instability for a protein of known sequence could thus be used as an index for predicting its stability characteristics.     

Effect of prolactin on DNA methylation in the liver and kidney of rat

Prolactin is an important growth modulatory hormone in fetal and adult tissues. It stimulates DNA synthesis and enzymatic markers of the G1 phase of cell cycle in rat liver and other tissues. In this study the effects of prolactin on 5-methyl cytosine content in liver and kidney of rats was studied using HPLC. Prolactin treatment caused hypomethylation of DNA in the liver and kidney of immature rats at 48 h after treatment and the effect remained even at 72 h. Prolactin also caused hypomethylation of DNA in the kidney and liver of adult rats at 48 h after treatment. These results indicate that prolactin probably regulates DNA methylation in the liver and kidney of immature and adult rats.     

Ester Production by Pseudomonas fragi IV. Demonstration of Esterase Activity

Assay of the esterase activity of sonically treated cell-free extracts, whole cell suspensions, and supernatant fluid of Pseudomonas fragi cultures with a differential respirometer revealed that the esterases were intracellular. Polyacrylamide-gel electrophoresis demonstrated six bands of esterase activity, which revealed substrate specificity differences. Band 1 exhibited slow mobility, bands 2, 3, and 4 moderate mobility, and bands 5 and 6 rapid mobility. Six bands were active with alpha-naphthyl acetate, four bands with alpha-naphthyl propionate, and 5 bands with alphanaphthyl butyrate. These esterases appeared to be more active with aromatic esters than with aliphatic esters.     

Associative growth studies in three-strain mixtures of lactic streptococci

A recently developed differential agar medium was used to study associative growth patterns in 17 different heterologous, three-strain mixtures of Streptococcus lactis, S. cremoris, and S. diacetilactis grown in milk. Mixtures were made by combining equal volumes of 18-hr milk cultures of the three species. Relative populations of component species were followed through three successive transfers in milk after the initial mixed propagation. Direct evidence for strain dominance and compatibility was obtained. A procedure also was developed to estimate the extent of suppression of S. lactis and S. diacetilactis in a mixture containing a dominant S. cremoris strain. The technique described could be successfully applied in quality-control work in the dairy-starter manufacturing industry.     

Ferredoxin- and Nicotinamide Adenine Dinucleotide-Dependent H2 Production from Ethanol and Formate in Extracts of S Organism Isolated from “Methanobacillus omelianskii”

S organism ferments ethanol to acetate and H(2) but grows poorly on ethanol unless the partial pressure of H(2) is kept low, as when it is grown in combination with an H(2)-utilizing methanogenic bacterium. The present study shows that S organism contains an alcohol dehydrogenase and a formate dehydrogenase, both of which require nicotinamide adenine dinucleotide (NAD) for activity. Hydrogen is evolved from NADH generated by these activities via a ferredoxin-dependent oxidation of NADH to NAD and H(2). NADH:NADP oxido-reductase activity was also demonstrated. The relationship of these activities to the growth of S organism is discussed.     

EFFECT OF SALINITY ON POLLEN I. POLLEN VIABILITY AS ALTERED BY INCREASING OSMOTIC PRESSURE WITH NaCl,MgCl2, and CaCl2

Petunia (Petunia hybrida Vilm. cv. ‘Snowstorm') plants were grown in saline solution (NaCl, MgCl₂, and/or CaCl₂) of 0, 1, 2, and 3 bars osmotic pressures. Pollen viability was tested by tetrazolium chloride staining and by germination (by the hanging drop method, using 15 % sucrose and 0.01 % boric acid as the nutrient medium, at 27 ± 1 C). Pollen viability decreased with increased salinity. Pollen from plants grown in single salt solutions of NaCl, MgCl₂, and CaCl₂ (each at 0, 1, 2, or 3 bars osmotic pressure) was germinated in base culture medium. Pollen viability decreased more with NaCl than with MgCl₂ or CaCl₂. In vitro studies of the effects of three salts, viz., NaCl, MgCl₂, and CaCl₂, on pollen germination and tube growth showed that NaCl inhibited germination and pollen tube growth more than did MgCl₂ or CaCl₂. MgCl₂ was least injurious, and even promoted tube growth at 0.5 and 0.75 bars osmotic pressure. Adding low concentrations of MgCl₂ reduced the toxic effect of NaCl and increased the percentage of germination. CaCl₂ reduced the effect of NaCl less than did MgCl₂. We conclude that specific ion effects were more important than osmotic pressure.     

MICROBODIES IN EXPERIMENTALLY ALTERED CELLS : II. The Relationship of Microbody Proliferation to Endocrine Glands

The liver cells of intact male rats given ethyl-α-p-chlorophenoxyisobutyrate (CPIB) characteristically show a marked increase in microbodies and in catalase activity, while those of intact female rats do not. In castrated males given estradiol benzoate and CPIB the increase in catalase activity and microbody proliferation is abolished, while in castrated females given testosterone propionate and CPIB the livers show a marked increase in microbodies and in catalase activity. No sex difference in microbody and catalase response is apparent in fetal and neonatal rats. Both sexes show a sharp rise in catalase activity on the day of birth, with a rapid decline at 5 days after birth. Thyroidectomy abolishes the hypolipidemic effect of CPIB in rats, but microbody proliferation and increase in catalase activity persists in thyroidectomized male rats, indicating that microbody proliferation can be independent of hypolipidemia. Adrenalectomy does not alter appreciably the microbody-catalase response to CPIB. These experiments demonstrate that (1) in adult rats, hepatic microbody proliferation is dependent to a significant degree upon male sex hormone but is largely independent of thyroid or adrenal gland hormones; (2) hepatic microbody proliferation is independent of the hypolipidemic effect of CPIB; (3) displacement of thyroxine from serum protein may not be sufficient cause for stimulation of microbody formation.     

Ester Production by Pseudomonas fragi. II. Factors Influencing Ester Levels in Milk Cultures

Cultures of Pseudomonas fragi were grown at 21 C in sterile homogenized milk and reconstituted skim milk media supplemented with ethyl alcohol. Quantitative determinations of ethyl butyrate and ethyl hexanoate by gas-liquid chromatography showed definite increases in the concentrations of the two esters produced in these media in comparison to media not supplemented with ethyl alcohol. Supplementation with butyric acid in addition to ethyl alcohol generally elevated the ethyl butyrate concentration and usually depressed the cell count slightly. Aeration of any of the media during growth tended to reduce the cell population slightly. A relationship between increase in cell number and increase in concentration of esters during the growth of the culture was observed. Media containing high concentrations of ethyl alcohol plus milk fat or low-molecular-weight fatty acids were conducive to the production of a fruity aroma by P. fragi.