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71.
Measures of geographic range size: the effects of sample size 总被引:2,自引:0,他引:2
A number of methods have been used for quantifying the sizes of the geographic ranges of species. The consequences of different levels of sampling (the proportion of actual spatial occurrences) are explored for eight of these, using data on the occurrences of butterfly species on a 10 × 10 km grid across Britain. For all methods, the percentage error of estimation (PEE) decreases with the number of 10 × 10 km squares which a species occupies, most rapidly for extent measures, and more rapidly for area measures than for measures of numbers of units occupied. The rate of decline in PEE itself falls as sampling effort increases. At a given sampling level, rank correlations between range sizes measured by different methods are generally high, but there is no consistent change in the magnitude of these correlations as the level of sampling increases. The composition of the set of species with the smallest range sizes changes with the level of sampling. 相似文献
72.
Stuart L. Myers Richard Turnage Kevin Kadesky Lori Bartula Angela Riva Barbara Kalley-Taylor 《Prostaglandins & other lipid mediators》1995,50(1)
This study examines the hypothesis that PAF stimulates release of PGI2 from inflamed rabbit gallbladder explant cell cultures. New Zealand white rabbits underwent bile duct ligation for 72 h (72 h BDL), or sham operation, Sham and 72 h BDL gallbladder explants were placed in culture, and the cells grown to 75% confluence. The cells were exposed to increasing concentrations of PAF for 60 min. The media analyzed for eicosanoid release by EIA and the cells analyzed for cyclooxygenase and prostacyclin synthase content by immunoblot analysis. PAF increased release of 6-keto-PGF1α from the 72 h BDL gallbladder cell cultures in a dose-related manner which was inhibited by indomethacin preincubation by 90%. The increased 72 h BDL cell release of 6-keto-PGF1α was not associated with changes in the content of cyclooxygenase or prostacyclin synthase. PAF did not alter eicosanoid release from sham control cell cultures. These data suggest that PAF can only up-regulate endogenous 6-keto-PGF1α release from the 72 h BDL cells that had been previously stimulated by inflammation. PAF may thus contribute to gallbladder distention and injury by chronic stimulation of inflamed gallbladder PGI2 release. 相似文献
73.
An Immunological Assay for Detection and Enumeration of Thermophilic Biomining Microorganisms 总被引:2,自引:1,他引:1 下载免费PDF全文
Ana M. Amaro Kevin B. Hallberg E. Brje Lindstrm Carlos A. Jerez 《Applied microbiology》1994,60(9):3470-3473
A specific, fast, and sensitive nonradioactive immunobinding assay for the detection and enumeration of the moderate thermophile Thiobacillus caldus and the thermophilic archaeon Sulfolobus acidocaldarius was developed. It employs enhanced chemiluminescence or peroxidase-conjugated immunoglobulins in a dot or slot blotting system and is very convenient for monitoring thermophilic bioleaching microorganisms in effluents from industrial bioleaching processes. 相似文献
74.
Jan Kwiatowski Douglas Skarecky Kevin Bailey Francisco J. Ayala 《Journal of molecular evolution》1994,38(5):443-454
The phylogeny and taxonomy of the drosophilids have been the subject of extensive investigations. Recently, Grimaldi (1990)
has challenged some common conceptions, and several sets of molecular data have provided information not always compatible
with other taxonomic knowledge or consistent with each other. We present the coding nucleotide sequence of the Cu,Zn superoxide
dismutase gene (Sod) for 15 species, which include the medfly Ceratitis capitata (family Tephritidae), the genera Chymomyza and Zaprionus, and representatives of the subgenera Dorsilopha, Drosophila, Hirtodrosophila, Scaptodrosophila, and Sophophora. Phylogenetic analysis of the Sod sequences indicates that Scaptodrosophila and Chymomyza branched off the main lineage before the major Drosophila radiations. The presence of a second intron in Chymomyza and Scaptodrosophila (as well as in the medfly) confirms the early divergence of these two taxa. This second intron became deleted from the main
lineage before the major Drosophila radiations. According to the Sod sequences, Sophophora (including the melanogaster, obscura, saltans, and willistoni species groups) is older than the subgenus Drosophila; a deep branch splits the willistoni and saltans groups from the melanogaster and obscura groups. The genus Zaprionus and the subgenera Dorsilopha and Hirtodrosophila appear as branches of a prolific “bush” that also embraces the numerous species of the subgenus Drosophila. The Sod results corroborate in many, but not all, respects Throckmorton's (King, R.C. (ed) Handbook of Genetics. Plenum Press, New York, pp. 421–469, 1975) phylogeny; are inconsistent in some important ways with Grimaldi's (Bull. Am. Museum Nat. Hist.
197:1–139, 1990) cladistic analysis; and also are inconsistent with some inferences based on mitochondrial DNA data. The Sod results manifest how, in addition to the information derived from nucleotide sequences, structural features (i.e., the deletion
of an intron) can help resolve phylogenetic issues.
Correspondence requests to: F. J. Ayala 相似文献
75.
Ethylbenzene degradation by Pseudomonas fluorescens strain CA-4 总被引:2,自引:0,他引:2
David M. Corkery Kevin E. O'Connor Catherine M. Buckley Alan D.W. Dobson 《FEMS microbiology letters》1994,124(1):23-27
Abstract Pseudomonas fluorescens strain CA-4 is a bioreactor isolate capable of ethylbenzene degradation. Transposon mutagenesis and enzyme assays have been performed which allow us to propose the ethylbenzene degradative pathway in operation in this strain. Ethylbenzene is initially converted to 2-phenylethanol. This is degraded to phenylacetaldehyde and then to phenylacetic acid. The major inducer of the pathway is ethylbenzene itself. The pathway is regulated by the presence of non-aromatic carbon sources. Oxidation of ethylbenzene is repressed by glutamate, but not by citrate or glucose. A clone from a chromosomal library has been found to complement a mutant deficient in the ability to convert ethylbenzene to 2-phenylethanol. 相似文献
76.
The preconditions are outlined for enantioselective separations in capillary electrophoresis (CE) with chiral selectors as additives to the background electrolyte. Free solution capillary electrophoresis conditions are characterised by a single solution phase. Chiral separations are reviewed by selector type (chiral ligand exchange, cyclodextrins, crown ethers, glycoproteins) with the extensive studies on cyclodextrins grouped into sections on amino acids, pharmaceuticals, and speciality chemicals, optimisation, biological fluids, and quantitative aspects. In micellar electrokinetic capillary chromatography, enantioselective discrimination occurs by partition in a two-phase system, with a chiral micellar phase as selector. Optimum separation conditions can be readily predicted for a given selector–selectand combination, and absolute values of binding constants determined by CE. Advantages of CE in comparison with HPLC using a chiral stationary phase include robust, rapid assays and the use of small volumes of aqueous solutions; disadvantages include less favourable detection limits. © 1994 Wiley-Liss, Inc. 相似文献
77.
C. David Pauza Peter Emau Maria S. Salvato Parul Trivedi Debra MacKenzie Miroslav Malkovsky Hideo Uno Kevin T. Schultz 《Journal of medical primatology》1993,22(2-3):154-161
Intrarectal inoculation of rhesus monkeys with low doses of SIVmac led to a prolonged clinical and virological latency that was not observed for high intrarectal doses or for intravenous inoculation. Animals infected intrarectally with low virus doses remained negative for serum antibody responses to SIV for at least one year even though they readily transferred SIV to naive recipients via transfusion of whole blood. 相似文献
78.
79.
Bradley B. Olwin Kirstin Arthur Kevin Hannon Patrick Hein Zhaohui Zhou Michael E. Zuber Arthur J. Kudla Aidan McFall Alan C. Rapraeger Bruce Riley Gyrgyi Szebenyi John F. Fallon 《Molecular reproduction and development》1994,39(1):90-101
Fibroblast growth factors (FGFs) are a family of nine proteins that bind to three distinct types of cell surface molecules: (i) FGF receptor tyrosine kinases (FGFR-1 through FGFR-4); (ii) a cysteine-rich FGF receptor (CFR); and (iii) heparan sulfate proteoglycans (HSPGs). Signaling by FGFs requires participation of at least two of these receptors: the FGFRs and HSPGs form a signaling complex. The length and sulfation pattern of the heparan sulfate chain determines both the activity of the signaling complex and, in part, the ligand specificity for FGFR-1. Thus, the heparan sulfate proteoglycans are likely to play an essential role in signaling. We have recently identified a role for FGF in limb bud development in vivo. In the chick limb bud, ectopic expression of the 18 kDa form of FGF-2 or FGF-2 fused to an artificial signal peptide at its amino terminus causes skeletal duplications. These data, and the observations that FGF-2 is localized to the subjacent mesoderm and the apical ectodermal ridge in the early developing limb, suggest that FGF-2 plays an important role in limb outgrowth. We propose that FGF-2 is an apical ectodermal ridgederived factor that participates in limb outgrowth and patterning. © 1994 Wiley-Liss, Inc. 相似文献
80.
The species ofSavoryella from freshwater are discussed and a key is provided.Savoryella grandispora sp. nov. from Malaysia is described and illustrated with interference contrast micrographs. 相似文献