ght2 + is required for UDP-galactose synthesis from extracellular galactose by Schizosaccharomyces pombe

Schizosaccharomyces pombe has eight hexose transporter genes, ght1 ⁺ to ght8 ⁺. Here we report that ght2 ⁺, which is highly expressed in the presence of glucose, is essential for UDP-galactose synthesis from extracellular galactose when cells grow on glucose. The galactosylation defect of a uge1Δ mutant defective in synthesis of UDP-galactose from glucose was suppressed in galactose-containing medium, but disruption of ght2 ⁺ in the uge1Δ mutant reversed suppression of the galactosylation defect. Expression of Saccharomyces cerevisiae GAL2 in uge1Δght2Δ cells suppressed the defective galactosylation phenotype in galactose-containing medium. These results indicate that galactose is transported from the medium to the cytosol in a Ght2-dependent manner, and is then converted into UDP-galactose.     

Cell Kinetic Study of Human Carcinomas Using Bromodeoxyuridine

Abstract. Cell kinetics in human malignant tumours were studied in vivo using bromodeoxyuridine (BrdU) and immunohistochemistry. BrdU was administered to twenty-four patients with gastric cancer at a dose of 1 g pre-operatively. Specimens were obtained during the operation, fixed in 70% ethanol and embedded in paraffin. BrdU-incorporating cells were detected by immunohistochemical staining using anti-BrdU monoclonal antibody. the labelling index (LI), determined by counting tumour cells microscopically, ranged from 4.0 to 41.4%. the LI was higher at the site of invasion than in the central area of the tumour, but no correlation was found between histological differentiation and LI. the LI of stage I gastric cancer was statistically lower than that of stage II, III and IV gastric cancers (P < 0.005). This technique, which is less cumbersome and time-consuming than using radioactive isotopes of thymidine, appears to be useful for studying cell kinetics of human malignant tumours.     

Dynamical conformational change of DNA induced by synthetic polymers: direct observation by fluorescence microscopy.

Brownian motion and Higher-order structure of DNA molecules complexed with synthetic polymers: poly-L-arginine (pArg) and polyacrylamide (pAAm), were observed using fluorescence microscopy. Quantitative analyses of the conformation and motion of the complexes demonstrate that these two polymers influence the structure of DNA molecules in an opposite way. The electrostatic binding of pArg induces contraction of DNA, whereas the intercalative pseudo-grafting of pAAm extends DNA.     

Purification and characterization of aqualysin I (a thermophilic alkaline serine protease) produced by Thermus aquaticus YT-1

Aqualysin I is an alkaline serine protease which is secreted into the culture medium by Thermus aquaticus YT-1. Aqualysin I was purified, and its apparent relative molecular mass was determined to be 28 500. The enzyme contained four Cys residues (probably as two cystines), and its amino acids composition was similar to those of cysteine-containing serine proteases (proteinase K, etc.) as well as those of subtilisins. The NH2-terminal sequence of aqualysin I showed homology with those of the microbial serine proteases. The optimum pH for the proteolytic activity of aqualysin I was around 10.0. Ca2+ stabilized the enzyme to heat treatment, and the maximum proteolytic activity was observed at 80 degrees C. Aqualysin I was stable to denaturing reagents (7 M urea, 6 M guanidine.HCl and 1% SDS) at 23 degrees C for 24 h. The enzyme hydrolyzed the ester bond of an alanine ester and succinyl-Ala-Ala-Ala p-nitroanilide, a synthetic substrate for mammalian elastase. The cleavage sites for aqualysin I in oxidized insulin B chain were not specific when it was digested completely.