Characterization of the lipopolysaccharide ofVeillonella parvula ATN and growth conditions affecting its yield

The lipopolysaccharide (LPS) ofVeillonella parvula ATN, a human oral isolate, was characterized. Lipid A accounted for, approximately 55% of the weight of the LPS complex. Major fatty acids included tridecanoic acid, 3-hydroxytridecanoic acid, and 3-hydroxypentadecanoic acid. Glucose was the only hexose detected. Amino compounds included glucosamine, galactosamine, and glycine. Heptose and 2-keto-3-deoxyoctonic acid (KDO) were also present. Alterations in the culture medium formulation affected LPS extraction yields. Furthermore, evidence was presented for the existence of a heterogeneous LPS component, with changes in growth conditions giving rise to more or less hydrophilic types of LPS.     

Weigle reactivation of diploid M13 phage

Molecular Genetics and Genomics - The limited ability of ultraviolet (UV)-irradiated E. coli cells to W-reactivate UV-irradiated, single-stranded DNA phages fd and M13 was investigated. The...     

Molecular characterization of choline acetyltransferase from Drosophila melanogaster

Purified acetyl-CoA: choline O-acetyltransferase (EC 2.3.1.6) from Drosophila melanogaster has been shown to contain two major polypeptides of 67 and 54 K Daltons. However, all enzyme activity is found in a single molecular weight form of approx 67 K Daltons as determined by sucrose gradient sedimentation and molecular exclusion chromatography. The latter showed both the 67 and 54 K Dalton polypeptides on polyacrylamide gel electrophoresis in sodium lauryl sulfate (10% acrylamide). Analysis of purified choline acetyltransferase on polyacrylamide gel electrophoresis in sodium lauryl sulfate (15% acrylamide) revealed the presence of an additional polypeptide at 13 K Daltons. Tryptic-peptide maps of the 67, 54 and 13 K Dalton components showed all three to be structurally related. In addition to several common tryptic peptides, the 13 K Dalton polypeptide contained three tryptic-peptides that were also found in the 67 K Dalton polypeptide, but were absent from the 54 K Dalton polypeptide. This evidence suggests that native Drosophila choline acetyltransferase may exist in two forms, one a single polypeptide chain with a molecular weight of 67 K Daltons and the other consisting of two noncovalently bound polypeptide chains with molecular weights of 54 and 13 K Daltons. The latter form is the major one isolated and may be generated by limited proteolysis of the single chain 67 K Dalton form.     

Glutathione stability and oxidative stress in P. falciparum infection in vitro: Responses of normal and G6PD deficient cells

Red cell oxidative stress in P. falciparum infection in vitro was investigated in relation to the G6PD-Malaria hypothesis. Glutathione stability was enhanced in infected red cells; glucose consumption and pentose pathway activity were not different in normal and G6PD deficient cells, although parasite growth was impaired in G6PD deficiency. Evidence for a response to oxidative stress was not found. Infected red cells have glutamate dehydrogenase activity which was not found in uninfected cells. This enzyme provides a separate pathway for the generation of NADPH independent from the pentose shunt. The data suggest that a significant oxidative stress is not present in falciparum malaria and that another mechanism may be operative in G6PD deficiency.     

Bounded survival

The useful and flexible “generic” family of parametric survival functions has been extended to cover the case of a hypothesized bound on the lifespan. The resulting model can be considered to be analogous to a simple system of three chemical reactions where survivors are lost, and where hazard (risk) and senescence are increased. Tables of one, two, and three parameter special cases, including single hit, Gompertz, Weibull, extreme value, and Burr functions, are presented. An application to a published life table is briefly discussed.