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81.
Hatching asynchrony in the house wren, Troglodytes aedon: a test of the brood-reduction hypothesis 总被引:1,自引:0,他引:1
We tested the brood-reduction hypothesis by adding three nestlingsto naturally occurring synchronous and asynchronous broods ofthe house wren (Troglodytes aedon) in order to mimic food shortagesfor the broods. Two types of controls were established in whichbrood size remained unchanged: those in which nestlings wereexchanged among broods and those in which no nestlings wereexchanged. The critical test of the hypothesis was in 1988 whenthere was a food shortage for enlarged broods. Although broodreduction occurred, enlarged synchronous broods produced asmany fledglings as did enlarged asynchronous broods, and fledgingmass was similar. Juvenile recapture 2-8 weeks after fledgingand offspring recruitment to subsequent breeding populationswere not related to treatment. The results are not consistentwith the brood-reduction hypothesis as an explanation for theoccurrence of hatching asynchrony in the house wren. 相似文献
82.
PATMAT: a searching and extraction program for sequence, pattern and block queries and databases 总被引:2,自引:0,他引:2
A program has been developed that provides molecular biologistswith multiple tools for searching databases, yet uses a verysimple interface. PATMATcan use protein or (translated) DNAsequences, patterns or blocks of aligned proteins as queriesof databases consisting of amino acid or nucleotide sequences,patterns or blocks. The ability to search databases of blocksby on-the-fly conversion to scoring matrices providesa new tool for detection and evaluation of distant relationships.PATMAT uses a pull-down, menu-driven interface to carry outits multiple searching, extraction and viewing functions. Eachquery or database type is recognized, reported, and the appropriatesearch carried out, with matches and alignments reported inwindows as they occur. Any of the high scoring matches can beexported to a file, viewed and recalled as a query using onlya few keystrokes or mouse selections. Searches of multiple databasefiles are carried out by user selection within a window. PATMATruns under DOS; the searching engine also runs under UNIX. 相似文献
83.
Twelve strains ofLegionella pneumophila were tested for the presence of plasmid DNA. Three strains, belonging to serogroup 1, had large plasmids of 83.8×106 daltons, as determined by electron microscopy. A fourth strain, also from serogroup 1, had a similar large plasmid in addition to a smaller plasmid. Restriction analysis of plasmid DNA isolated from the strains with a single size plasmid indicated that the plasmids were structurally very similar. The biologic functions of these plasmids are yet to be determined. 相似文献
84.
Dr. Edward B. Blanchard Frank Andrasik Susan E. Jurish Steven J. Teders 《Applied psychophysiology and biofeedback》1982,7(2):185-191
Eleven patients with episodic cluster headache were assessed and offered a treatment program consisting of 8 weeks of training in abbreviated progressive relaxation followed by 12 sessions of thermal biofeedback. Four dropped out before treatment began. Of the seven who completed the full treatment regimen, three (27% of initial sample) reported some degree of improvement when their next cluster bout occurred. In no one was the disorder eliminated.This research was supported by a grant from the National Institute of Neurological and Communicative Disorders and Stroke, NS-15235. 相似文献
85.
86.
Steven Martindale 《Journal of theoretical biology》1980,83(1):107-110
In a recent paper in this journal, Sparling & Williams (1978) demonstrated several multivariate techniques by applying them to measurements of albatross calls. Their paper contains a useful summary of the literature, but includes several misleading interpretations of the analyses. Since the stated purpose of that article was to familiarize biologists with proper uses of the statistical methods, it is important to clarify the problems, some of which I discuss below. I then mention how such techniques are likely to be particularly valuable in the near future, when coupled with real-time sound spectrum analysis. 相似文献
87.
Three methods of estimating bacterial productivity were compared using parallel samples of Atlantic Ocean water (within 0.25–15 km of the Georgia coast). The frequency-of-dividing cells (FDC) method and the [3H]thymidine incorporation method gave results which were strongly correlated (r=0.97), but the FDC estimates were always higher (X2 to X7) than the [3H]thymidine estimates. Estimates of bacterial productivity ranged from 2–4×108 cells·l–1·h–1 at 0.25 km from shore to 1–9×107cells·l–1·h–1 at 15 km. A method involving incubation of 3-m filtrates and direct counting gave results that could not be easily translated into estimates of bacterial productivity. Application of the FDC method to sediment samples gave high productivity estimates, which could be not reconciled with productivity estimates based on sediment oxygen uptake. 相似文献
88.
Christopher B. Capelle James T. Meyer Steven E. Sorensen Steven B. Oppenheimer 《Experimental cell research》1981,131(2):470-476
An aggregation inhibitory factor (AIF) has been extracted from mouse ascites teratoma cells (that do not aggregate in culture) that retards adhesion of cultured teratoma cells of the same cell line (that do aggregate). Preliminary characterization of AIF on polyacrylamide gels suggests that AIF is a protein composed of four subunits. Extraction of AIF from ascites teratoma cells was accomplished without significant loss of viability by a technique involving the application of an electric field to large numbers of whole cells suspended in a hypertonic electrode buffer. In tests of adhesion, AIF consistently and immediately inhibited aggregation of cultured teratoma cells after 5, 10, 15, and 30 min of incubation. Furthermore, a reduced concentration of AIF resulted in a corresponding decrease in inhibition, suggesting a concentration-dependent action. AIF may help explain how cultured teratoma cells adhere, whereas ascites teratoma cells of the same subline do not adhere. 相似文献
89.
Analysis of the nucleoside triphosphate pyrophosphohydrolase specific activity of red cells obtained from a random Caucasian population indicated at least two subclasses. The specific activity of 18% of the population ranged from undetectable activity to 27.5 nmol ITP cleaved/20 min/mg hemoglobin. The remainder of the population had higher activity, 27.5–125 nmoles ITP cleaved/20 min/mg hemoglobin. The variation of NTPH activity evident in the red cells of an individual is reflected in granulocytes, lymphocytes, and platelets of that individual. Erythrocyte activity ranges from 0.7 to 21 units (nmol of ITP cleaved in 20 min)/107 cells, granulocytes have 17–201 units/107 cells, lymphocytes have 91–462 units/107 cells, and platelets have 1.1–7.1 units/107 platelets. These cell differences are discussed with respect to the hypothesis that NTPH prevents incorporation of ITP or dITP into nucleic acids.This work was supported by funds allocated by the Agricultural Experiment Station, Michigan State University. Michigan Agricultural Experiment Station Journal No. 8727. 相似文献
90.