Correlation Between Degradation of Bacteriophage T2 Deoxyribonucleic Acid and the Resistance of Escherichia coli to Infection

The ability of certain strains of Escherichia coli to degrade T2 deoxyribonucleic acid to acid-soluble fragments is correlated with their high capacity to survive T2 infection.     

Synergistic effects of metabolically related amino acids on the growth of a multicellular plant

The effects of several amino acids related to the metabolism of aspartic acid on the growth and development of gemmalings of the liverwort Marchantia polymorpha were investigated under axenic conditions. Lysine and theonine synergistically inhibit the growth of these plants and cause a loss of normal pigmentation at concentrations as low as 1 μm. These effects are highly specific for this pair of amino acids, are partially reversible upon removal of the effectors, and can be prevented by low concentrations of methionine or its metabolic precursor, homoserine. Alterations in the growth and development of gemmalings in the presence of natural amino acids are discussed in relation to metabolic regulatory mechanisms which have been well established in microorganisms.     

Androgen sulphate formation in male and female mice

1. After the administration of large doses of androsterone, epiandrosterone, dehydroepiandrosterone and testosterone to mice, females excreted more of the dose conjugated with sulphuric acid than did males. 2. Liver slices from female mice conjugated androgens with sulphuric acid to a greater extent than did slices from males. 3. Sulphotransferase preparations from livers of female rats and mice catalysed the formation of dehydroepiandrosterone sulphate at a faster rate than preparations from livers of the male animals. 4. A possible explanation for the observed sex differences is discussed.     

Purification and characterization of bovine aorta ribonucleases

1. Two ribonucleases (aorta ribonuclease I and aorta ribonuclease II) from bovine aorta were purified 4611-fold and 667-fold respectively. Ethanolic precipitation, acid extraction, isoionic precipitation at pH3.5 and Bio-Rex 70 column chromatography were the methods employed. 2. Aorta ribonuclease I exhibited no deoxyribonuclease or alkaline phosphatase activity. 3. Aorta ribonuclease I appeared to be homogeneous when subjected to discontinuous gel electrophoresis. 4. Aorta ribonuclease II exhibited the same properties as aorta ribonuclease previously isolated. 5. The activities of the aorta ribonucleases and pancreatic ribonuclease on homopolymers and dinucleoside phosphates were compared. 6. Aorta ribonuclease I exhibited optimum pH7.5 and, under the assay conditions used, optimum temperature 60 degrees .     

Detection of Lymphocytic Choriomeningitis Virus Antibody in Murine Sera by Immunofluorescence

An immunofluorescence technique developed for detection of antibody in murine sera to lymphocyitc choriomeningitis virus is described.     

Mycobacterial Polysaccharides II. Comparison of Polysaccharides from Strains of Four Species of Mycobacteria

Evidence from chemical and serological studies indicates that a cellular heteropolysaccharide, also found in lipid extracts and culture filtrate, is present as a group antigen in Mycobacterium tuberculosis H37Ra and in other strains of mycobacteria representing M. kansasii, scotochromogenic and Battey strains. Polysaccharides from the four strains contain the same main sugars, arabinose, and galactose, as revealed by thin-layer chromatography and spectrophotometric studies. In Ouchterlony gel diffusions, bands of identity are produced between the polysaccharides by using rabbit antiserum prepared against any of the four mycobacteria. Immune adsorption studies also confirm the presence of identical antigenic determinant groups. In skin tests with tuberculopolysaccharide I, a skin reaction of about equal size was elicited in guinea pigs sensitized with either M. tuberculosis H37Ra or heterologous mycobacterial antigens in Freund's incomplete adjuvant. In animals sensitized with M. tuberculosis H37Ra, skin tests with both homologous and heterologous polysaccharides elicited similar responses.