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1.
S J Getting L Gibbs A J Clark R J Flower M Perretti 《Journal of immunology (Baltimore, Md. : 1950)》1999,162(12):7446-7453
To investigate the relevance of adrenocorticotrophic hormone (ACTH) therapy in human gouty arthritis, we have tested the effect of several ACTH-related peptides in a murine model of experimental gout. Systemic treatment of mice with ACTH4-10 (MEHFRWG) (10-200 microgram s. c.) inhibited neutrophil accumulation without altering peripheral blood cell counts or circulating corticosterone levels. A similar effect was seen with alpha- and beta-melanocyte stimulating hormones (1-30 microgram s.c.). In vivo release of the chemokine KC-(detected in the lavage fluids before maximal influx of neutrophils) was significantly reduced (-50 to -60%) by ACTH4-10. Macrophage activation in vitro, determined as phagocytosis and KC release, was inhibited by ACTH and ACTH4-10 with approximate IC50 values of 30 nM and 100 microM, respectively. The melanocortin receptor type 3/4 antagonist SHU9119 prevented the inhibitory actions of ACTH4-10 both in vitro and in vivo. However, melanocortin type 3, but not type 4, receptor mRNA was detected in mouse peritoneal macrophages by RT-PCR. Therefore, we propose that activation of this receptor type by ACTH4-10 and related amino acid sequences attenuates KC release (and possibly production of other cytokines) from macrophages with consequent inhibition of the host inflammatory response, thus providing a notional anti-inflammatory mechanism for ACTH that is unrelated to stimulation of glucocorticoid release. 相似文献
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R. J. Flower 《Hydrobiologia》1986,143(1):93-103
The species composition of surface sediment diatom assemblages in 33 Galloway lakes, pH range c. 4.5 to 7.4, is related in a statistically significant manner to water acidity (or to factors closely associated with pH). Predictive models of summer mean pH, using simple regression equations of Index B (Renberg & Hellberg, 1982) with both Scandinavian and Galloway data sets, and multiple regression equations using diatom pH preference groups and individual species, are described and applied to fossil diatoms in six sediment cores. Although multiple regression of individual species gives the highest correlation coefficient (r2=0.87) in the modern data set this method is least appropriate for reconstructing pH values from fossil material where predictor species are often absent. Of the four methods examined here it is suggested that multiple regression of diatom preference groups is probably the most suitable for pH reconstructions from sediment cores. 相似文献
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Restoration goals for damaged freshwater habitats can bedefinedaccording to ecological as well as to chemical criteria. Fordisturbed lakes, the sediment microfossil record can be usedtoselect potential modern analogue sites as possible restorationtarget ecosystems.Fossil diatom assemblages in two acidified lakes (Round LochofGlenhead and Loch Dee) in Galloway, Scotland, were comparedfloristically with modern surface sediment samples from ca. 200lakes in Britain, Ireland, Sweden and Norway using numericaltechniques. Mean squared Chi-squared dissimilarity (SCD)valuesbased on between sample Chi-square distance measures were usedtocompare samples.Space-for-time substitution using diatom assemblage matchingtechniques identified several modern analogue sites withHebrideanLoch Teanga and Irish Lough Claggan possessing modern diatomflorasmost similar to those which existed at the Round Loch ofGlenheadand Loch Dee before acidification.From the point of view of atmospheric pollution, the mostcloselymatching modern analogue sites were not necessarily in themostpristine regions. Some analogues occurred in UK regions ofmoderateor low acid deposition and modern diatom assemblages inatmospherically cleaner mid Norway were generally less similarfloristically.It is argued that identification of modern analogue sitesraisesthe possibility of using time-space substitution of closelymatchedmodern and fossil samples to infer whole lake ecosystems.Diatoms are however poor indicators of some water chemistryvariables and the two closest matched modern analogue siteshavetoo high calcium concentrations making faunistic comparisonsquestionable.Identification of good modern analogue lakes can be improvedbyusing selection criteria, other than diatoms, to pre-selectsites.Screening inappropriate sites according to water chemistry andbasin features combined with a larger biological database ofmodernand fossil samples offers a promising way of refining theselectionprocesses.Despite necessary refinements, modern analogue matching canpotentially identify whole lake ecosystems that can serve asbiological target communities for currently disturbed sites.Beingbased on biological rather than chemical criteria, thisapproachdoes not rely on species-water chemistry transfer functions.It istherefore directly relevant to lake conservation andrestorationobjectives and offers an alternative method for reconstructing lakepalaeo-environments. 相似文献
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A highly conserved nuclear gene for low-level phylogenetics: elongation factor-1 alpha recovers morphology-based tree for heliothine moths 总被引:8,自引:2,他引:6
Cho S; Mitchell A; Regier JC; Mitter C; Poole RW; Friedlander TP; Zhao S 《Molecular biology and evolution》1995,12(4):650-656
Molecular systematists need increased access to nuclear genes. Highly
conserved, low copy number protein-encoding nuclear genes have attractive
features for phylogenetic inference but have heretofore been applied mostly
to very ancient divergences. By virtue of their synonymous substitutions,
such genes should contain a wealth of information about lower-level
taxonomic relationships as well, with the advantage that amino acid
conservatism makes both alignment and primer definition straightforward. We
tested this postulate for the elongation factor-1 alpha (EF-1 alpha) gene
in the noctuid moth subfamily Heliothinae, which has probably diversified
since the middle Tertiary. We sequenced 1,240 bp in 18 taxa representing
heliothine groupings strongly supported by previous morphological and
allozyme studies. The single most parsimonious gene tree and the
neighbor-joining tree for all nucleotides show almost complete concordance
with the morphological tree. Homoplasy and pairwise divergence levels are
low, transition/transversion ratios are high, and phylogenetic information
is spread evenly across gene regions. The EF-1 alpha gene and presumably
other highly conserved genes hold much promise for phylogenetics of
Tertiary age eukaryote groups.
相似文献
10.
Darren R. Flower 《Journal of molecular recognition : JMR》1995,8(3):185-195
The lipocalins, a diverse family of small extracellular ligand proteins, display a remarkable range of different molecular properties. While their binding of small hydrophobic molecules, and to a lesser extent their binding to cell surface receptors, is well known, it is shown here that formation of macromolecular complexes is also a common feature of this family. Analysis of known crystallographic structures reveals that the lipocalins process a conserved common structure: an antiparallel β-barrel with a repeated +1 topology. Comparisons show that within this overall similarity the structure of individual proteins is specifically adapted to bind their particular ligands, forming a binding site from an internal cavity (within the barrel) and/or an external loop scaffold, which gives rise to different binding modes that reflects the need to accommodate ligands of different shape, size, and chemical structure. The architecture of the lipocalin fold suggests that the both the ends and sides of this barrel are topologically distinct, differences also apparent in analyses of structural and sequence variation within the family. These different can be linked to experimental evidence suggesting a possible functional dichotomy between the two ends of the lipocalin fold. The structurally invariant end of the molecule may be implicated in general binding small ligands and forming macromolecular complexes via an exposed binding surface. 相似文献