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Sökning: L773:0028 0836 OR L773:1476 4687 > (1980-1989) > (1989)

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  • Ahlberg, Per E. (författare)
  • Fossil fishes from Gogo
  • 1989
  • Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 337, s. 511-512
  • Tidskriftsartikel (övrigt vetenskapligt)
  • Björck, Lars, et al. (författare)
  • Bacterial growth inhibited by a synthetic inhibitor based upon the structure of a human proteinase inhibitor
  • 1989
  • Ingår i: Nature. - Nature Publishing Group. - 0028-0836. ; 337:6205, s. 385-386
  • Tidskriftsartikel (refereegranskat)abstract
    • Cysteine proteinases are important not only in the intracellular catabolism of peptides and proteins1 and in the processing of prohormones and proenzymes2,3, but also in the penetration of normal human tissue by malignant cells4 and possibly microorganisms5, including viruses. Cystatin C is a human cysteine proteinase inhibitor present in extracellular fluids6. We have synthesized peptide derivatives mimicking the proposed proteinase-binding centre of cystatin C7 and find that they irreversibly inhibit cysteine proteinases. Several bacteria produce proteinases, so we tested a tripeptide derivative (Z-LVG-CHN2) for in vitro anti-bacterial activity against a large number of bacterial strains belonging to thirteen different species. It was found to inhibit specifically the growth of all strains of group A streptococci. The susceptibility of these human pathogens to the peptide was compared with that to well-established anti-streptococcal antibiotics such as tetracy-cline and bacitracin. Moreover, the peptide was active in vivo against group A streptococci: mice injected with lethal doses of these bacteria were cured by a single injection of Z-LVG-CHN2. The cysteine proteinase produced by group A streptococci was isolated and found to be inhibited by Z-LVG-CHN2; moreover, excess proteinase relieved the growth inhibition caused by the peptide derivative, suggesting that the antibacterial activity of Z-LVG-CHN2 is due to inhibition of this cysteine proteinase. This strategy of blocking proteinases with peptide derivatives that mimic naturally occurring inhibitors could be useful in the construction of new agents against other microorganisms, including viruses.
  • Olsén, Arne, et al. (författare)
  • Fibronectin binding mediated by a novel class of surface organelles on Escherichia coli
  • 1989
  • Ingår i: Nature. - 0028-0836. ; 338:6217, s. 652-5
  • Tidskriftsartikel (refereegranskat)abstract
    • Gram-negative bacteria are known to produce two types of surface organelles: flagella, which are required for motility and chemotaxis, and pili (fimbriae), which play a part in the interaction of bacteria with other bacteria and with eukaryotic host cells. Here we report a third class of E. coli surface organelles for which we propose the name curli. Curli are coiled surface structures composed of a single type of subunit, the curlin, which differs from all known pilin proteins and is synthesized in the absence of a cleavable signal peptide. Although the gene encoding this structural subunit, crl, is present and transcribed in most natural isolates of E. coli, only certain strains are able to assemble the subunit protein into curli. This assembly process occurs preferentially at growth temperatures below 37 degrees C. The ability of curli to mediate binding to fibronectin may be a virulence-associated property for wound colonization and for the colonization of fibronectin-coated surfaces.
  • Schantz, T von, et al. (författare)
  • Female choice selects for a viability-based male trait in pheasants
  • 1989
  • Ingår i: Nature. - Nature Publishing Group. - 0028-0836. ; 337:6203, s. 166-169
  • Tidskriftsartikel (refereegranskat)abstract
    • Recent theory on sexual selection1–4 suggests that females in species without paternal care choose mates by their secondary sexual characters because these indicate genotypic quality which will be transmitted to the offspring. These ideas are not yet empiri-cally supported as data quantifying the relationship between female mate choice and female reproductive success are lacking. Only in one case, in Colias butterflies, has it been demonstrated unequivo-cally that females choose 'good genotypes' as mates5 and there is only one study, on Drosophila, demonstrating that mate choice increases one component of offspring fitness6. Spur length of male pheasants (Phasianus colchicus) correlates with various fitness-related properties7. We here present the first experimental field data showing that female pheasants select mates on the basis of male spur length and that female mate choice correlates with female reproductive success.
  • von Schantz, Torbjörn, et al. (författare)
  • Female choice - Reply
  • 1989
  • Ingår i: Nature. - Nature Publishing Group. - 0028-0836. ; 339:6224, s. 432-433
  • Tidskriftsartikel (refereegranskat)
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