Legionella sainthelensi: a new species of Legionella isolated from water near Mt. St. Helens

Six strains of a new species, Legionella sainthelensi, were isolated from freshwater in areas affected by the volcanic eruptions of Mt. St. Helens in the state of Washington. Strains of L. sainthelensi are culturally and biochemically similar to other legionellae. They grow on buffered charcoal yeast agar but not on media that lack cysteine. They are gram-negative, nonsporeforming, motile rods that are positive in reactions for catalase, oxidase, gelatin liquefaction, and beta-lactamase. They are negative in reactions for urease, hydrolysis of hippurate, reduction of nitrates, fermentation of glucose, and blue-white autofluorescence. Their cell wall fatty acid composition is qualitatively similar to those of other legionellae, with 50 to 62% branched-chain fatty acids. They contain the isobranched-chain 14- and 16-carbon acids and anteisobranched-chain 15- and 17-carbon acids and relatively large amounts of straight-chain 16-carbon acid. All strains of L. sainthelensi contain approximately equal amounts of ubiquinones Q9, Q10, Q11, and Q12, a pattern similar to those of Legionella bozemanii, Legionella dumoffi, and Legionella longbeachae. Serological cross-reactions were observed between L. sainthelensi, both serogroups of L. longbeachae, and Legionella oakridgensis. Three strains of L. sainthelensi were greater than 90% related by DNA hybridization. The type strain of L. sainthelensi, Mt. St. Helens 4, was 36% related to the type strain of L. longbeachae and 3 to 14% related to the other nine described Legionella species.     

On the stochastic treatment of fast chemical reactions

A Monte Carlo code was developed to stimulate stochastically the fast reactions of radiolysis products in water. The results of these calculations show that treatments based on deterministic kinetic rate equations do not reproduce correctly the evolution in time of the number of species. Ad hoc initial distributions of species in spurs, of the type used in deterministic approaches, are compared with more realistic distributions obtained from Monte Carlo-generated particle tracks. The effects of using either type of distribution, stochastically or deterministically, are discussed.     

Effect of fatty acids of ω6 series on the biosynthesis of arachidonic acid in HTC cells

Summary The influence of the preincubation of HTC cells with fatty acids of 6 series and columbinic acid (St, 9c, 12c 18:3) on the biosynthesis of arachidonic acid was studied. The cells were incubated on a chemically defined medium with or without the addition of unlabeled linoleic, -linolenic, eicosatrienoic, arachidonic, docosatetraenoic, docosapentaenoic and columbinic acids. After 24 hr of preincubation in the presence of the aforementioned fatty acids, [1-¹⁴C]eicosa-8,11,14-trienoic acid was added to the culture medium as the only lipidic source. Twenty-four hours later the synthesis of arachidonic acid and the fatty acid composition of the cells were determined. At 20 MM concentration the 6 fatty acids studied except docosapentaenoic acid produced an increase on the biosynthesis of arachidonic acid compared to the cells incubated in the absence of unlabeled fatty acids in the medium. The fatty acids added to the culture medium were incorporated into the cells and modified their fatty acid composition. Columbinic acid, with a similar structure to linoleic acid, also produced a significant increase on the conversion of eicosatrienoic acid to arachidonic acid. These results would suggest that the effect of both, linoleic and columbinic acids, may be adscribed to their configuration and not necessarily to their transformation in higher homologs, since columbinic acid is unable to be desaturated.All authors are members of the Carrera del Investigador Cientifico of the Consejo Nacional de Investigaciones Cientifícas y Técnicas, Argentina.     

Mutants affecting paramyosin in Caenorhabditis elegans

Four mutants of Caenorhabditis elegans with abnormal muscle structure are described which are alleles of a single locus unc-15. In one of the mutants, E1214, paramyosin is completely absent from both body-wall and pharyngeal musculature. In the other three mutants paramyosin is present but does not assemble into thick filaments. Instead paramyosin paracrystals are formed in the body-wall muscle cells. Myosin filaments lacking paramyosin cores are present in all four mutants, but these filaments fail to integrate stably into the myofilament lattice. One mutant is temperature-sensitive; all four are semi-dominant in their effect on muscle structure. The hypothesis that unc-15 is the structural gene for paramyosin is discussed.     

Influence of molecular configuration on the passage of macromolecules across the glomerular capillary wall

The influence of molecular configuration on the filtration of macromolecules across glomerular capillary walls was examined by comparing fractional clearances of two uncharged polysaccharides of distinctly different molecular configuration in the Munich-Wistar rat. The macromolecules employed were dextran, a slightly branched polymer of glucopyranose, and ficoll, a highly cross-linked copolymer of sucrose and epichlorohydrin. Differences in effective shape between these two polymers were determined from measurements of several physical properties of aqueous solutions containing either dextran or ficoll. It was found that dextran is best represented as a prolate ellipsoid with axial ratios of 4, 9, and 16 for molecules with Stokes-Einstein radii of 22, 32, and 40 A, respectively. On the other hand, ficoll is more closely approximated as spherical since the axial ratio was found to be between 1 and 2 for all molecular sizes. Fractional clearances of dextran and ficoll ranging in effective radius from 18 to 44 A were determined in each of seven Munich-Wistar rats. Fractional clearances of dextran were found to be greater than those of ficoll, the difference being significant for molecular radii ranging from 24 to 44 A. In addition, as shown previously for dextran, ficoll was found to be neither secreted nor reabsorbed by the renal tubules. These results, therefore, suggest that in addition to molecular size and charge, molecular configuration is also a determinant of the filtration of macromolecules across the glomerular capillary wall.     

Study on the composition-structure relationship of lipophorins

High density lipophorin (HDLp is the main lipoprotein found in resting insect hemolymph. It has, in general, two molecules of apolipoproteins: apoLp-I (250 kDa) and apoLp-II (80 kDa) and a variable lipid content which ranges from 35% to 59% (w/w). Diacylglycerols (DG), phospholipids (PL), and hydrocarbons (HC) are the main lipid components, whereas cholesterol and triacylglycerols are minor components. DG content varies from 7 to 30%, PL from 11 to 24%, and HC from 0 to 15%. In order to determine the relationship between the lipid composition and the arrangement of lipid and protein components in the lipoprotein particle, a density-composition structural model was designed. The model was established by means of 12 sets of data on lipophorin density-composition relationships, and model validity was determined throughout lipoprotein space- and surface-filling conditions. Despite the differences among the lipid compositions of lipophorins, it is concluded that there are several unifying structural restrictions that govern the molecular organization of lipophorins. Quantitative treatment of the model indicates that lipophorin structure is consistent with the following. 1) Spherical particles with a protein-rich outer layer of approximately 20-21 A thickness, comprised of proteins, phospholipids, cholesterol, and small amounts of DG, and a lipid-rich core composed of HC, TG, and almost all the lipophorin DG. 2) Apolipophorins have a lipid-embedded localization within the lipoprotein particle. They might represent one of the few examples of proteins containing beta-shift structure, exerting strong hydrophobic interaction and having a lipid-embedded localization.(ABSTRACT TRUNCATED AT 250 WORDS)     

An efficient method for isolation of plasmid DNA from methylotrophic bacteria

A method, suitable for the isolation of closed circular plasmid DNA from methylotrophic bacteria is described. Improvement of cell lysis was achieved by butanol extraction of cells before application of the lytic agent. Using this method, cryptic plasmids of 7.8, 14, 36 and 200 kb were purified from soil-isolated methylotrophs.     

Heterogeneity of cell surface endothelin receptors

Two distinct cell surface endothelin receptors were identified, namely a 73-kDa protein referred to as ET-R1 and a 60-kDa protein named ET-R2. ET-R1 was expressed as the sole endothelin receptor on rat A10 vascular smooth muscle cells and C6 glial cells. Binding of 125I-ET-1 to these cells was inhibited by 50-200 pM endothelin-1 and -2, whereas endothelin-3 did not compete for this receptor subtype. Binding of 125I-ET-1 to intact A10 and C6 cells was reversible, indicating that ET-R1 is located on the cell surface. Affinity labelling of a single 73-kDa band on sodium dodecyl sulfate-polyacrylamide gels by 125I-ET-1 in A10 and C6 cells was inhibited by endothelin-1 but not by endothelin-3. In A10 cells, endothelin-1 but not endothelin-3 elicited a concentration-dependent increase in intracellular inositol trisphosphate levels. ET-R1 was also expressed in cultured rat glomerular mesangial cells based on findings of a subset of receptors with an apparent molecular mass of 73 kDa that bound 125I-ET-1 displacable by endothelin-1 and endothelin-2 but not by endothelin-3. These cells also expressed the ET-R2 receptor subtype, based on findings of a 60-kDa binding site that could be labeled by both 125I-ET-1 and 125I-ET-3. Labeling of ET-R2 by the radioactive endothelins-1 and -3 was inhibited competitively by endothelins-1, -2, and -3. Furthermore, ET-R2 was shown to be a functional receptor, as endothelin-3 caused inositol trisphosphate levels to rise in mesangial cells. An endothelin binding site with high affinity for endothelin-3 was also identified on rat PC12 pheochromocytoma cells, although the apparent molecular mass of this receptor could not be verified by cross-linking studies. Since endothelin-1 or -3 failed to augment inositol trisphosphate levels in these cells, this binding site could represent a third endothelin receptor subtype. Thus, two distinct functional receptors for endothelins were identified on rat cells, namely the 73-kDa ET-R1 which has an exceedingly low affinity for endothelin-3 and the 60-kDa ET-R2 which binds endothelin-3 with high affinity. Whether an additional endothelin receptor subtype exists in PC12 cells remains to be shown with certainty.     

Discrimination and consistency of five myosin ATPase stains in human normal and duchenne dystrophic muscle

Summary Limitations in the ability of the human visual system to assess accurately the relative staining densities of individual fibers in muscle tissue stained for myosin ATPase can complicate the objective evaluation of fiber type populations. In this study a novel approach is employed which utilizes human visual capabilities to provide accurate fiber classification. Using this approach, the ability of five ATPase staining techniques to discriminate fiber type categories in single samples of human normal and Duchenne dystrophic skeletal muscle is evaluated, as is the consistency of the fiber type classifications between stains. While no major discrepancies in fiber typing were observed in the sample of normal muscle, significant differences in classification, along with a decrease in the ability to discriminate fiber types were noted in the sample of Duchenne muscular dystrophy. For the most part, these discrepancies were resolved by a re-interpretation of the staining characteristics of fibers in one stain.This work was supported in part by NIH grant NS 15584, and by a grant from the Muscular Dystrophy Association     

Deoxyribonucleic acid relatedness inYersinia enterocolitica andYersinia enterocolitica-like organisms

Yersinia enterocolitica andY. enterocolitica-like strains were characterized by DNA relatedness. These strains formed four distinct DNA relatedness groups: (i) the 5 classical biotypes ofY. enterocolitica sensu stricto as designated by Wauters; (ii) strains that are rhamnose positive and also positive in tests for melibiose, α-methyl-d-glucoside, raffinose, and Simmons' citrate; (iii) strains that are rhamnose positive but negative in tests for melibiose, α-methyl-d-glucoside, and raffinose; (iv) sucrose-negative, Voges-Proskauer-negative, trehalose-positive strains.