首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
A K Agarwal 《Experientia》1976,32(12):1518-1520
Trehalase from the salivary glands and the midgut of Sesamia inferens showed optimum activity at pH 5.8, and at temperatures of 50 and 60 degrees C respectively. The increase in the incubation period, enzyme concentration, and substrate concentration respectively increased the end-product, the hydrolysis, and the rate of hydrolysis of the substrate. Dialysis did not affect, tryptophan accelerated, and other amino acids and end-product inhibited the enzyme activity.  相似文献   

2.
Summary The pH and temperature for the optimum activity of trypsin from the midgut ofSarcophaga ruficornis andMusca domestica was 7.5 and 8.0 respectively and 50°C. The enzymic activity increased with the increase in incubation period and enzyme concentration.Thanks are due to Prof.R. Rakshpal for guidance.  相似文献   

3.
Summary Probabilistic ideas and methods from Newton's writings are discussed in § 1: Newton's ideas pertaining to the definition of probability, his probabilistic method in chronology, his probabilistic ideas and method in the theory of errors and his probabilistic reasonings on the system of the world. Newton's predecessors and his influence upon subsequent scholars are dealt with in §2: beginning with his predecessors the discussion continues with his contemporaries Arbuthnot and De Moiver, then Bentley. The section ends with Laplace, whose determinism is seen as a development of the Newtonian determinism.An addendum is devoted to Lambert's reasoning on randomness and to the influence of Darwin on statistics. A synopsis is attached at the end of the article.Abbreviations PT abridged Philosophical Transactions of the Royal Society 1665–1800 abridged. London, 1809 - Todhunter I. Todhunter, History of the mathematical theory of probability, Cambridge, 1865 To the memory of my mother, Sophia Sheynin (1900–1970)  相似文献   

4.
Summary The ability of dog renal cortex slices to accumulate -methyl-glucoside or glycine is enhanced by the flavonoid (+)-catechin at a concentration of 3.5 mM. This stimulatory effect is apparently due to a decreased rate of efflux of either substrate. On the other hand, the uptake of p-amino-hippuric acid and N1-methyl-nicotinamide is inhibited by (+)-catechin. The drug at the same concentration is without action on amino-acid transport by guineapig intestine in vitro.This study was supported by grants from Zyma S.A., Nyon. We are grateful to MmesH. Capt andP. Ganguillet and MlleD. Mettraux for their skilful technical assistance.  相似文献   

5.
Over the past years, accumulating evidence has indicated that d-serine is the endogenous ligand for the glycine-modulatory binding site on the NR1 subunit of N-methyl-d-aspartate receptors in various brain areas. d-Serine is synthesized in glial cells and neurons by the pyridoxal-5′ phosphate-dependent enzyme serine racemase, and it is released upon activation of glutamate receptors. The cellular concentration of this novel messenger is regulated by both serine racemase isomerization and elimination reactions, as well as by its selective degradation catalyzed by the flavin adenine dinucleotide-containing flavoenzyme d-amino acid oxidase. Here, we present an overview of the current knowledge of the metabolism of d-serine in human brain at the molecular and cellular levels, with a specific emphasis on the brain localization and regulatory pathways of d-serine, serine racemase, and d-amino acid oxidase. Furthermore, we discuss how d-serine is involved with specific pathological conditions related to N-methyl-d-aspartate receptors over- or down-regulation.  相似文献   

6.
Summary The PGE2-induced cyclic AMP accumulation in the rat anterior pituitary in vitro is inhibited by [desamino1]-, [desamino1] [descarboxy14] and [d-Lys4]-somatostatin similarly to somatostatin, while the [descarboxy14]-somatostatin exhibits reduced activity; [d-Lys9]-somatostatin is ineffective at a higher concentration.The authors acknowledge the technical assistance ofG. Alexander. F. Bellini, D. Mangerel andJ. Rochon and thank Dr.G. Schilling and his associates for the analytical data.  相似文献   

7.
Summary N-(o-Carboxybenzoyl)-dl-glutamic acid imide anddl-glutamic acid imide · HCl did not lead to fetal malformations after i.p. administration to pregnant mice; the injected solutions contained 25% Tween 20. Thus, of the 12 hydrolysis products of thalidomide only those 3 which contain the phthalimide moiety show teratogenic activity, i.e. 2-phthalimido-dl-glutaramic acid, 4-phthalimido-dl-glutaramic acid and 2-phthalimido-dl-glutaric acid.  相似文献   

8.
Summary Attention has previously been drawn to a specific effect of NHCP on embryonicPleurodeles cell differentiation. With a modified NHCP labelling technique, autoradiography has revealed a cytoplasmic concentration of labelled NHCP and has not revealed any difference between homospecific and heterospecific NHCP penetration.This work has been supported financially by research grants from the C.N.R.S. (ERA No. 327 and ATP No. 4310 on the cellular differentiation), and INSERM (No. 711019).The authors wish to extend their thands to Dr.Mazarguil who kindly initiated us in the techniques of enzyme binding. Many thanks are also due to Mr.Hawks for most valuable help in correcting the English.  相似文献   

9.
Zusammenfassung Die ultrastruktuelle Untersuchung des Haftorgans vonCardiocephaloides physalis (Trematoda) lässt eine mit Aushöhlungen versehene zellplasmatische Oberfläche erkennen, die mit der lamina propria der Wirtsdarmzotte (Phalacrocorax bougainvillei) in engstem Kontakt steht und möglicherweise Plazenta-funktion besitzt.

I am extremely grateful to Prof.Baer for his interest and generosity in sending me the specimens, and to Mr. T.Davies for his technical assistance.  相似文献   

10.
Zusammenfassung Von den Blutzellen derPhallusia mamillata Cuvier zeigen nur die stark vakuolisierten (compartment cells) im UV-Licht eine stabile blaue Fluoreszenz ( max =5200 und 4600 Å). Sie ist in den Zellgranula lokalisiert. Bei den Blutzellen vonCiona intestinalis L. tritt dagegen eine gelbe Fluoreszenz ( max = 5900, 5200 und 4600 Å) auf, die nur von den Vanadocyten ausgeht. Diese Fluoreszenz, welche auch von den Testazellen der Oocyten gegeben wird, geht innerhalb einiger Minuten in die blaue Fluoreszenz über.

This work has been carried out in the Stazione Zoologica, Napoli (director Dr.P. Dohrn) and in the Istituto di Biologia Generale e Genetica della Università di Napoli (director Prof. Dr.B. de Lerma). —M. de Vincentiis wishes to thank Dr,P. Dohrn for placing at his disposal a working place of the Consiglio Nazionale delle Ricerche, Roma. —W. Rüdiger thanks sincerely the Deutsche Forschungsgemeinschaft, Bad Godesberg, for providing grants, and Prof. Dr.H.-J. Bielig for his interest.  相似文献   

11.
Summary Emulsin (Rohferment ofHelferich) and similar enzyme preparations ofRosaceae-Amygdaloideae seeds have been found to exhibit a low but definite oxidizing activity towards aldohexoses in concentrated sugar solutions used for transglycosylation experiments.  相似文献   

12.
Summary Biological and statistical aspects of the application of variance to mean ratio to describe spatial distribution of animals are discussed. It is shown that the parameterb inTaylor's power laws 2=a m b shows intra-specific variation depending on the distribution of the constituent units of the population.a andb are only parameters of a very empirical way of describing the relation between variance and mean, which itself is an indicator for spatial distribution. Hence,a andb depend on the distribution behaviour of the animals, and not vice versa.Acknowledgments: The work was developed whilst I was at the Department of Entomology, University of Nairobi. I am grateful to ProfessorT. R. Odhiambo for his interest. I thank the referee for comments.  相似文献   

13.
Résumé Présentation d'une hypothèse pour la phosphorylation oxidative qui comprend des substances vinyl carbonyl, suivie d'une esquisse d'un système cyclique utilisant des quinones, hydroxyquinones, hydroxy-hydroquinones et leurs dérivés phosphorilatés.

This investigation was supported by the grant of a Special Fellowship, Division of Medical Sciences; and partially supported by grant C-2399 National Cancer Institute, National Institutes of Health; Department of Health Education and Welfare.

The abbreviations used are DPN diphosphopyridine nucleotide, DPNH reduced diphosphopyridine nucleotide, ATP Adenosine triphosphate, ADP Adenosine diphosphate, Pi orthophosphate, P/O ratio of atoms of phosphorous and oxygen coupled through oxidative phosphorylation, DNP 2,4-dinitrophenol, E enzyme.

Acknowledgement: Thanks are due Dr.H. A. Lardy for his enthusiastic support, Dr.W. W. Cleland for his interest, and Mr.L. R. Gignilliat III for his counsel.  相似文献   

14.
Summary The teratogenicity of 3 hydrolysis products of thalidomide, 2-(o-carboxybenzamido)-glutaric acid, phthalic acid and glutamic acid, was determined by administering 25% Tween 20 i.p. to pregnant SWS-mice. Under these experimental conditions, the tested products were devoid of any teratogenic properties, whereas thel-isomer of phthaloyl-glutamic acid showed the well-known embryotoxic and teratogenic activity.  相似文献   

15.
In the last half of the 16th century, the method of casting a solar image through an aperture onto a screen for the purposes of observing the sun and its eclipses came into increasing use among professional astronomers. In particular, Tycho Brahe adapted most of his instruments to solar observations, both of positions and of apparent diameters, by fitting the upper pinnule of his diopters with an aperture and allowing the lower pinnule with an engraved centering circle to serve as a screen. In conjunction with these innovations a method of calculating apparent solar diameters on the basis of the measured size of the image was developed, but the method was almost entirely empirically based and developed without the assistance of an adequate theory of the formation of images behind small apertures. Thus resulted the unsuccessful extension of the method by Tycho to the quantitative observation of apparent lunar diameters during solar eclipses. Kepler's attention to the eclipse of July 1600, prompted by Tycho's anomalous results, gave him occasion to consider the relevant theory of measurement. The result was a fully articulated account of pinhole images. Dedicated to the memory of Ronald Cameron Riddell (29.1.1938–11.1.1981)  相似文献   

16.
Summary Cyclic AMP was determined during the development of the dipteraCeratitis capitata. The concentration of the nucleotide reaches a peak at apolysis with a sharp decline in the pharate adult stage. A gradual increase takes place through the longevity of adult stage reaching a maximum plateau at the end of life.We are indebted to Prof.A. M. Municio for advice and encouragement and Mr.V. G. Corces for technical assistance.  相似文献   

17.
Zusammenfassung Ein auf Blättern vonEugenia jambolana Lam. in Indien Blattflecken verursachender Ascomycet gehört zu einer neuen Gattung,Muelleromyces Kamat undAnahosur; Typus istMuelleromyces indicus Kamat undAnahosur. Der Pilz hat dem Blattgewebe eingesenkte, einzelstehende und von einem mächtig entwickelten Klypeus überdeckte Perithecien, verschleimende Asci und ungleich zweizellige, hyaline Ascosporen; Paraphysen fehlen.

The fungus is named after Dr.E. Müller of The Institute of Special Botany, Zürich (Switzerland), in recognition of his outstanding contributions to Fungi in general and Ascomycetes in particular. The material of this new fungus is deposited at M.A.C.S. Herb. Poona (India), C.M.I., Kew, Surrey (England) and Herb. Orientalis, New Delhi (India).  相似文献   

18.
Zusammenfassung Zehn der vonLeupold isolierten UV-induzierten Mutanten beim Adenin-1-Gen vonSchizosaccharomyces pombe sind in zehn verschiedenen Stellen im Gen lokalisiert.

I am extremely grateful to ProfessorU. Leupold for his help and hospitality in his laboratory, and to Dr.Charlotte Auerbach for her encouragement and interest.  相似文献   

19.
Summary I attempt to solve the enigma of how de Moivre derived his recursion formulae and the formulae for the probability of a duration of exactly n games. I believe that he obtained the latter probability by differencing Nicholas Bernoulli's formula for the probability of ruin and that he obtained the recursion formulae by a simple algebraic method and induction.  相似文献   

20.
Site- and state-specific lysine methylation of histones is catalyzed by a family of proteins that contain the evolutionarily conserved SET domain and plays a fundamental role in epigenetic regulation of gene activation and silencing in all eukaryotes. The recently determined three-dimensional structures of the SET domains from chromosomal proteins reveal that the core SET domain structure contains a two-domain architecture, consisting of a conserved anti-parallel β-barrel and a structurally variable insert that surround a unusual knot-like structure that comprises the enzyme active site. These structures of the SET domains, either in the free state or when bound to cofactor S-adenosyl-L-homocysteine and/or histone peptide, mimicking an enzyme/cofactor/substrate complex, further yield the structural insights into the molecular basis of the substrate specificity, methylation multiplicity and the catalytic mechanism of histone lysine methylation. Received 10 June 2006; accepted 22 August 2006  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号