Role of neuraminic acid in the heterogeneity of alkaline phosphatase in sheep brain

1. Comparative studies of the polyuridylic acid-directed phenylalanine-incorporating activity of cell-free systems derived from rat and chicken livers demonstrated markedly lower activity in the chicken liver system. 2. The chicken liver cell sap contained the factor(s) responsible for this lower activity. Ribosomes from chicken and rat performed equally well in the presence of rat liver cell sap. Chicken liver cell sap, when mixed with rat liver cell sap, caused an inhibition of incorporation of phenylalanine into acid-insoluble material. 3. Though ribosomal preparations and cell sap from both rat and chicken liver degraded polyuridylic acid to some extent, the chicken liver cell sap contained the largest amount of activity. 4. Rat liver cell sap inhibited the nuclease activities of ribosomal preparations, but no such nuclease inhibition could be demonstrated with chicken liver cell sap.     

Histochemical localization of protein-polysaccharides in renal tissue

The purpose of this study was to investigate the distribution of protein-polysaccharides in the glomerular and non-glomerular regions of the nephron. The techniques used include the digestion of kidney slices with specific polysaccharidases: neuraminidase, hyaluronidase, chondroitinase ABC, and collagenase followed by several cytochemical techniques to identify the glycosaminoglycans and glycoproteins at the light and electron microscope levels. Differential staining of hyaluronic acid and sulphated glycosaminoglycans was accomplished with Alcian Blue at pH 2.5 and pH 0.5, respectively. Sialoproteins were stained with Alcian Blue at pH 2.5. The periodic acid Schiff’s reaction technique was employed for the visualization of collagen. At the electron microscope level the polysaccharides were identified with the periodic acid-chromic acid-silver methenamine reaction. Our results indicated that the major polysaccharide components of the glomerular basement membrane were sialoproteins and collagen, with smaller amounts of hyaluronic acid and various sulphated glycosaminoglycans. Hyaluronidase digestion resulted in partial detachment of epithelial processes from the glomerular basement membrane indicating the hyaluronic acid may have a role in the stability of the attachment of these processes. Tubular basement membranes also contain sialoproteins and sulphated glycosaminoglycans but in considerably lower concentrations than the glomerular basement membrane. Bowman’s capsule appears to contain mostly sulphated glycosaminoglycans and has a lower concentration of sialoproteins and hyaluronic acid.     

Effect of a lexA41(Ts) mutation on DNA repair in recA(Def) derivatives of Escherichia coli K-12

Summary Derivatives of Escherichia coli K-12 carrying a deletion of the recA gene survive exposure to UV (254 nm) better if they also contain the lexA41 mutation which codes for a labile LexA protein. This effect of the lexA41 mutation is not observed in comparable strains carrying a uvr A6 mutation. Using two independent methods to detect pyrimidine dimers we found that UV irradiated RecA deficient cells removed dimers from their DNA more rapidly if they contained the lexA41 mutation than if the contained the wild-type lexA gene. Our results are consistent with the idea that a relatively high level of UvrABC incision nuclease resulting from inefficient repression of the corresponding genes by the labile LexA41 protein facilitates excision of pyrimidine dimers from the DNA of UV irradiated cells.     

A genetic analysis of various functions of the TyrR protein of Escherichia coli.

The TyrR protein is involved in both repression and activation of the genes of the TyrR regulon. Correction of an error in a previously published sequence has revealed a Cro-like helix-turn-helix DNA-binding domain near the carboxyl terminus. Site-directed mutagenesis in this region has generated a number of mutants that can no longer repress or activate. Deletions of amino acid residues 5 to 42 produced a protein that could repress but not activate. The central domain of TyrR contains an ATP-binding site and is homologous with the NtrC family of activator proteins. A mutation to site A of the ATP-binding site and other mutations in this region affect tyrosine-mediated repression but do not prevent activation or phenylalanine-mediated repression of aroG.     

alpha1-Antitrypsin variants in different racial groups in Malaysia.

In a study of Malaysians of different racial groups, 1,510 sera (908 from Malays, 371 from Chinese and 231 from Indians) were identified for their protease inhibitor (Pi) types. The gene frequencies for the alleles PiM, PiS and PiX in Malays were, respectively, 0.979, 0.015, and 0.007. In Chinese, the frequencies were 0.981, 0.019 and 0.000, and in Indians they were 0.976, 0.24, and 0.000. It is interesting that the usually rare PiX type is found in appreciable frequency in the Malays. Two different types with unusual behavior and obscure origin were also found.     

Biochemical genetic markers in the Kadazans of Sabah,Malaysia

Summary Kadazans, the largest indigenous group in Sabah, northern Borneo, were surveyed for glyoxalase I, phosphoglucomutase I, red cell acid phosphatase, esterase D, adenosine deaminase, soluble glutamate pyruvate transaminase, soluble glutamate oxaloacetate transaminase, 6-phosphogluconate dehydrogenase, uridine monophosphate kinase, adenylate kinase, peptidase B and D, superoxide dismutase, C₅, group specific component, haptoglobin and transferrin.Kadazans were found to be polymorphic for GLOI, PGMI, RCAP, esterase D, ADA, s-Gpt, 6PGD, UMPK, Gc, C₅, haptoglobin and peptidase B. Rare variants were found for transferrin and peptidase D. No variant was found for s-Got, SOD and AK.     

Temperature-sensitive deoxyribonucleic acid replication in a dnaC mutant of Bacillus subtilis.

A temperature-sensitive mutant of Bacillus subtilis is defective in deoxyribonucleic acid (DNA) synthesis, contains a lesion in the dnaC locus, and is not primarily an initiation mutant. The amount of DNA synthesized by this mutant at temperatures above 40 C decreases with increasing temperature. DNA synthesis resumes within 20 min after the temperature is lowered to 30 C. In the presence of chloramphenical, DNA synthesis begins at a reduced rate after the temperature is lowered to 30 C. Spores germinated at 46 C cannot initiate DNA replication. The capacity for residual DNA synthesis is stable at the restrictive temperature during inhibition of DNA synthesis. When the temperature is lowered to 30 C after a period of incubation at 43 C, DNA synthesis starts at the origin of the chromosome as well as at preexisting growing points. Similar DNA synthesis patterns are found in mutant cells in vivo and after toluene treatment.