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a aaa a aa aa a a E. coli aa, a aa aa a , a a aa - a .

Laboratory of Biological Investigations.

Laboratory for Chemistry of Antibiotics.  相似文献   

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Defensive steroids from a carrion beetle (Silpha americana)   总被引:2,自引:0,他引:2  
Summary The defensive anal effluent discharged bySilpha americana in response to disturbance contains a mixture of steroids stemming from a glandular annex of the rectum. The compounds have been characterized as 15-hydroxyprogesterone (1, principal component), 5-pregnan-15-ol-3, 20-dione (2), 5-pregnan-3, 15-diol-20-one (3), 5-pregnan-7, 15-diol-3,20-dione (4), 5-pregnan-3, 7, 15-triol-20-one (5), 5-pregnan-16-ol-3,20-dione (6), and 5-pregnan-3, 16-diol-20-one (7), none previously found in insects. Bioassays with jumping spiders showed compounds1 and6 to be feeding deterrents at the 1 g level.Paper No. 78 of the series: Defense Mechanisms of Arthropods. Study supported by NIH (Grants AI-02908, AI-12020). We thank Maura Malarcher and Maria Eisner for excellent technical help, and the Squibb Institute of Medical Research for samples of authentic reference compounds.  相似文献   

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Summary Morphological transformations are often describable by simple series kinetic models,AB, ABC, etc., which allow assessment of the rates of interconversion of the distinguishable shapes or forms present and their probabilities of occurrence at various points in time, thus providing a means for kinetic comparisons with biochemical measurements of the molecular-level reactions that cause the transformations. When changes in cell morphology are followed turbidimetrically, the real-time progress curves can be simulated by fitting the data to a form of Beer's law for scattering by mixtures in which the species concentrations change with time in accordance with the chosen kinetic scheme. Because many even relatively large cells are mostly water, classical light scattering theory can be used to interpret the turbidimetric data in terms of simple geometrical models ofaverage cell size and shape suggested by microscopic examination. Two examples are briefly considered, the stimulus-induced changes in blood platelet shape and apparent size and their correlation with cytosolic-free calcium, and apparent swimming motion exhibited by neutrophils in suspension.What do you know about this business? the King said to Alice. Nothing, said Alice. Nothing whatever? persisted the King. Nothing whatever, said Alice. That's very important, the King said. Lewis Carroll (1865), in Alice's Adventures in Wonderland  相似文献   

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Summary Centrifugation techniques were used to determine the subcellular distribution of noradrenaline (NA) and dopamine -hydroxylase (DH) in the rabbit iris. By application of isopycnic and differential gradient centrifugation methods 2 types of NA vesicles could be demonstrated. Of the total particle bound NA about 70% is associated with light and about 30% with heavy vesicles. For both types of vesicles the distribution of DH reflected that of NA.  相似文献   

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Zusammenfassung Die Darstellung der beiden epimeren C21-Methylderivate des 9-Fluorprednisolons wird beschrieben. 9-Fluor-21-methyl-1, 4-pregnadien-11, 17, 21B-triol-3, 20-dion-21-azetat ist ein hochwirksames entzündungshemmendes Steroid, vollkommen frei von Nebenwirkungen der Natrium- und Wasserretention des C21-unsubstituierten 9-Fluorprednisolons.  相似文献   

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Summary [1-N4-Dimethyl-asparagine]-angiotensin II was synthesized by Merrifield's solid-phase procedure. The analogue gave rat blood pressure about 70% relative potency to Hypertensin (Ciba). Rabbit aorta strips gave intrinsic activity E=1, a PD2 of 6.92±0.09 and an affinity relative to [Asn1]-angiotensin II of 6.5%.The editors do not hold themselves responsible for the opinions expressed in the authors' brief reports. — Les auteurs sont seuls responsables des opinions exprimées dans ces brèves communications. — Für die Kurzmitteilungen ist ausschliesslich der Autor verantwortlich. — Per le brevi comunicazioni è responsabile solo l'autore. — . — Solo los autores son responsables de las opiniones expresadas en estas comunicationes breves.Acknowledgment. The authors wish to express their appreciation to Dr Emanuel Escher, School of Medicine, Centre Hospitalier Universitaire, Sherbrooke, Quebec, for his help in providing the biological data and critical comments.  相似文献   

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-Spermophilus brunneus . , 13 18 ,S. brunneus S. townsendii mollis (2n=38) , , ; ;S. brunneus . S. brunneus , Spermophilus.

Supported by National Science Foundation Grants No. GB32114X and No. GB 29131X, and the Sprague Foundation. We thankD. Pozin for technical assistance.  相似文献   

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