“Pleiotypic Response”

A hypothesis has been developed to relate stringent control in bacteria to a set of interactions involved in the regulation of growth of transformed and untransformed mammalian cells.     

Inhibition of DNA Synthesis but not of Poly-dAT Synthesis by the Arabinose Analogue of Cytidine <Emphasis Type="Italic">in vitro</Emphasis>

Kimball and Wilson¹ reported that the arabinose analogue of cytidine (ara-C) inhibited DNA polymerase in a crude extract prepared from Ehrlich ascites cells. Furth and Cohen² observed cytosine arabinoside triphosphate (ara-CTP) inhibited DNA polymerase in extracts from either calf thymus or bovine lymphosarcoma tissue, although these investigators³ had already found no effect of ara-CTP on DNA polymerase from Escherichia coli. The inhibition in both of these cases could be substantially reversed by dCTP; but incorporation of the arabinose nucleotide (ara-CMP) into DNA could not be unequivocally demonstrated. Graham and Whitmore⁴ reported the incorporation of ara-C into DNA in vivo and the inhibition of a DNA polymerase from L cells by ara-CTP. They found that ara-CMP was initially incorporated into small DNA strands but subsequently appeared in long strands. Momparler⁵ has presented evidence that, in vitro, ara-C incorporation was limited to the 3′-hydroxyl end of DNA chains. Such incorporation might be expected to block further chain elongation but this expectation was not supported by the evidence presented by Graham and Whitmore.     

Endopeptidase Activity of Phage λ-Endolysin

JACOB and Fuerst^1,2 demonstrated the presence of a bacteriolytic enzyme (λ-endolysin) in the induced cultures of lysogenic Escherichia coli K12 (λ). The enzyme was later identified as the product of gene R; of phage λ³ which is involved in bacterial lysis at the end of a latent period. The enzyme is apt to form spheroplast-like structures in E. coli² and one would therefore expect its substrate to be murein.     

Protection against acute paraquat toxicity by ambroxol

An expression vector for G-CSF, pASLB3-3, was constructed and introduced into Namalwa KJM-1 cells (Hosoi et al., 1988), and cells resistant to 100 nM of methotrexate (MTX) were obtained. Among them, the highest producer, clone SC57, was selected and the productivity of this clone was further characterized. The maximal production of G-CSF was at the most 1.8 g/ml/day using a 25 cm² tissue culture flask, even though the cell number was above 7×10⁵ cells/ml. The limiting factors at high density were analyzed as the deficiency of nutrients, such as glucose, cysteine and serine, and pH control. The depression of specific G-CSF productivity per cell under the batch culture conditions was overcome by using a perfusion culture system, Biofermenter^TM (Sato, 1983) with modifications of nutrients supplementation by a dialysis membrane and/or dissolved oxygen (DO) supplementation by microsilicone fibers. ITPSGF medium was modified to elevate concentrations of amino acids and glucose by 2.0- and 2.5-times, respectively. Under the control of pH at 7.4 and DO at 3 ppm, the specific G-CSF productivity was not depressed even at high cell density (above 1×10⁷ cells/ml), and the amount of G-CSF reached 41 g/ml. These results indicated the possibility of finding the optimum culture conditions for the production of recombinant proteins by Namalwa KJM-1 cells.Abbreviations ABTS 2,2-Azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid - BSA Bovine Serum Albumin - BSA-PBS Phosphate-buffered Saline without Ca²⁺ and Mg²⁺ containing Bovine Serum Albumin - dhfr Dihydrofolate Reductase - DO Dissolved Oxygen - G-CSF Granulocyte Colony-stimulating Factor - HEPES 4-(2-Hydroxyethyl)-1-piperazineethansulfonic Acid - IFN Interferon - MTX Methotrexate - PBS(-) Phosphate-buffered saline without Ca²⁺ and Mg²⁺ - Tween-PBS Phosphate-buffered saline without Ca²⁺ and Mg²⁺ containing 0.05% of Tween 20     

Persistence of influenza serum antibodies in humans following immunization with a bivalent A/Victoria and A/New Jersey vaccine.

The persistence of serum antibodies 1 year after immunization with a bivalent vaccine containing recombinant viruses that were antigenically identical with A/Victoria/3/75 (H3N2) and A/New Jersey/8/76 (Hsw1N1) viruses was measured in 128 persons aged 18 to 65 years. Serum samples were tested with the hemagglutination inhibition assay against the two vaccine antigens and against A/Texas/1/77 (H3N2) and A/USSR/90/77 (H1N1) viruses. Prior to vaccination 56% and 79% of the participants had been found to be seronegative to A/Victoria and A/New Jersey antigens respectively; the geometric mean antibody titres were low (1:5 to 1:11) except in persons aged 51 to 65 years, whose mean titre of antibody to the A/New Jersey antigen was 1:23, and persons aged 26 to 35 years, whose mean titre of antibody to the A/USSR antigen was 1:25. By 3 weeks after vaccination 85% of the seronegative persons had a fourfold or greater rise in titres of antibodies to the viruses in the vaccine, and 70% had a fourfold increase in titre of antibody to the A/Texas antigen. Of the persons aged 26 to 35 years (seronegative and seropositive) 68% had a fourfold or greater increase in titre of antibody to the A/USSR antigen. There was no change in the mean titres of 19 unvaccinated control subjects during the observation period. At 6 and 12 months after vaccination the titres of antibodies to the A/Victoria and A/New Jersey antigens had declined moderately in all age groups from those observed 3 weeks after vaccination. The rate of decline was similar for the various antibodies except that to the A/USSR antigen in persons 26 to 35 years of age, in whom the decline was much slower.     

Cytogenetics of the parthenogenetic grasshopper Warramaba (formerly Moraba) virgo and its bisexual relatives

Hybrids of both sexes were obtained from the reciprocal crosses, carried out in the laboratory, between the species believed to have given rise, by hybridization some thousands of years ago, to the parthenogenetic species W. virgo. All males with a Y-chromosome derived from P196 died before reaching the adult stage, but two males from the reciprocal cross (i.e., with a Y from P169) survived up to the adult stage. Their testes were small but normal in structure and histology. At the first meiotic division almost all the chromosomes were univalents, 0–2 bivalents being formed. Some chiasmata between non-homologous chromosomes were present. Segregation at first anaphase is irregular so that sperms with 3–15 chromosomes are formed. Such hybrids appear to be entirely sterile.     

Influence of clay minerals on sorption of bacteriolytic enzymes

Myxobacteria presumably produce extracellular bacteriolytic enzymes when they are growing in soil. In order to study their ecological significance, adsorption experiments were performed with lytic enzymes produced byMyxococcus virescens in casitone media. Different soils as well as montmorillonite and kaolinite can rapidly adsorb the bacteriolytic but not the proteolytic enzymes. About 1 gm of montmorillonite per liter of cell-free culture solution is enough for the adsorption of 97% of the bacteriolytic enzymes. The adsorption per unit weight is about 100 times greater on montmorillonite than on kaolinite. About 40% of the adsorbed enzymes can be eluted with solutions of high pH or high ionic strength. The only desorbed bacteriolytic enzyme is the alanyl-∈-N-lysine endopeptidase.     

Staining of Some Specific Regions of Human Chromosomes,particularly the Secondary Constriction of No. 9

SEVERAL procedures have been described recently which produce specific patterns of differential staining in human chromosomes^1–9. Techniques which involve DNA denaturation and reannealing reveal deeply stained areas on centromere and secondary constriction regions which have been equated with constitutive heterochromatin⁹.