Amebacidal action of cycloserine

Zusammenfassung Endamoeba histolytica wird durch Cycloserin abgetötet. Diese amöbizide Wirkung wird durch Adenin und Guanin teilweise verhindert und durch Adenosin, Guanosin, Adenylsäure, Guanylsäure und 2,6-Diaminopurin vollständig aufgehoben.     

Glycine methoxyamide,acyclic analog of cycloserine

Zusammenfassung Methoxy-glycinamid, ein offenkettiges Isomeres von Cycloserin, wurde hergestellt. Seine physikalischen Eigenschaften sind von denjenigen des Cycloserins stark verschieden. Es besitzt keine antibiotische Eigenschaft mehr.     

Synthesis of L-4-amino-3-isoxazolidinone,the unnatural stereoisomer of cycloserine and its antibiotic activity

Zusammenfassung Eine direkte Synthese vonl- undd-Cycloserin ausl- undd-Serin wurde beschrieben. Die bakteriostatischen Effekte der drei Formen von Cycloserin (d-,l-unddl-) aufE. coli in synthetischem Medium wurden verglichen.     

Effect of temperature on in situ feulgen reaction with schiff reagent at less acid pH

Zusammenfassung Die Feulgenfärbung geht umso besser, je höher im Bereich von 5–25°C die Temperatur ist. Als Material wurde Wasserbüffelniere verwendet.     

Increase of the amount of DNA-feulgen in mammalian tissue by schiff reagents at less acid pH

Zusammenfassung Die Färbbarkeit der DNS mit dem Feulgenreagens nimmt mit steigendem pH des Reagens zu. Es wird nachgewiesen, dass die verstärkte Reaktion alle 3 Bestandteile des gebräuchlichen Fuchsins betrifft.

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The author wishes to record his sincere appreciation to Prof.B. R. Seshachar for providing facilities to carry out this investigation. This work was supported in part by a research grant (GM 10499) from the National Institutes of Health, U.S. Public Health Service, to Prof.B. P. Kaufmann.     

Atypical base composition of foldback DNA

Summary Salmon, calf and human foldback DNAs all exhibited hypermethylation, reduced adenine plus thymine content and an excess of adenine over thymine when compared with their respective native DNAs. The only unusual feature of the base composition of wheat germ foldback DNA was the excess of thymine over adenine.This work was supported by grants from the Committee on Higher Degrees and Research Grants and the Department of Pathology, University of Hong Kong.This study was carried out in partial fulfillment of the requirements of the University of Hong Kong for the degree of Doctor of Philosophy.     

Incorporation of base analogues for detection of unusual base compositions in plant metaphase chromosomes (Vicia faba,Leguminosae)

Summary Bromodeoxyuridine and bromodeoxycytidine with fluorescence-plus-Giemsa staining resulted in similar patterns of asymmetric bands inVicia faba chromosomes. Limitations as to the use of methods for identification of A+T-and G+C-rich regions are discussed.Acknowledgements. We are grateful to Mr G. Versteegh. Groningen, for kindly providing us with a sample of BrdC and to Ms B. Hildebrandt for skilful technical assistance.     

On the presence of periodic acid schiff positive substances in the paraphysis cerebri,the choroid plexuses and the neuroglia of ambystoma mexicanum

Zusammenfassung Mittels Färbung mit der histochemischen Methode nachMcManus lässt sich eine grosse Menge Glykogen in derParaphysis cerebri vonAmbystoma nachweisen. Glykogentropfen finden sich weiter im Epithel desPlexus chorioideus und vor allem auch in den ependymalen Gliozyten, deren Ausläufer richtige Strassen zum Glykogentransport zu bilden scheinen.Es wird eine Arbeitshypothese aufgestellt, nach der das Glykogen, eine wichtige Energiequelle wie ein Baustein mehr komplexer chemischer Verbindungen, gebildet in der bei Amphibien mächtig entwickelten Paraphyse, in die ventrikuläre Cerebrospinalflüssigkeit gelangt, um von dort aus von den ependymalen Gliozyten aufgenommen und in das nervöse Parenchym hinein transportiert zu werden, wo es eine Rolle bei der Metabolie und dem strukturellen Aufbau spielen kann.

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This investigation was aided by a grant from the Health Organization of the Society for Applied Scientific Research, The Netherlands.     

Aspects biochimiques des herbicides à base de triazines

Summary The triazine herbicides are potent inhibitors of theHill reaction, resembling the phenylureas, acylanilides and carbamates. The inhibition of the photosynthesis by the triazines is the most obvious explanation for their mode of action in plant metabolism. Besides this there are also effects on light independent reactions where the effective concentrations are higher than those inhibiting the photosynthesis. Particularly, a positive influence of the triazines on the uptake of the nutrients by the roots was noted. Changes in the nitrogen metabolism of the plants, due to increased uptake of nitrate from the medium, result in a higher content of organic nitrogen in the plants.Several enzyme systems in plants and in micro-organisms are influenced by the triazine herbicides. Until now, the mechanism of action has not been elucidated.Concerning the phenomenon of the selectivity of the triazine herbicides, several factors may be responsible. The different abilities of the plant species to metabolize the herbicide and to translocate it to the active centres in the cells are significant from the biochemical point of view.

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Une partie de ce travail a été présentée lors de la 463^e séance de la Biochemical Society, Aberystwyth, septembre 1966.P. W. Müller, Biochem. J.101, 1P. (1966).Nous tenons à exprimer nos remerciements àR. Truan qui a bien voulu se charger de la version française ainsi qu'àG. Dupuis pour sa participation à la mise au point du manuscrit.     

A predicting system based on combining an adaptive predictor and a knowledge base as applied to a blast furnace

In this paper a system is proposed and applied to predicting silicon content in pig iron for a blast furnace. It combines an adaptive predictor with a knowledge base. On-line experiments show that the prediction accuracy of the system is much better than that of an experienced operator or of an adaptive predictor alone. Such a system will be helpful to operators in selecting desirable control methods.     

Functions of disordered regions in mammalian early base excision repair proteins

Reactive oxygen species, generated endogenously and induced as a toxic response, produce several dozen oxidized or modified bases and/or single-strand breaks in mammalian and other genomes. These lesions are predominantly repaired via the conserved base excision repair (BER) pathway. BER is initiated with excision of oxidized or modified bases by DNA glycosylases leading to formation of abasic (AP) site or strand break at the lesion site. Structural analysis by experimental and modeling approaches shows the presence of a disordered segment commonly localized at the N- or C-terminus as a characteristic signature of mammalian DNA glycosylases which is absent in their bacterial prototypes. Recent studies on unstructured regions in DNA metabolizing proteins have indicated their essential role in interaction with other proteins and target DNA recognition. In this review, we have discussed the unique presence of disordered segments in human DNA glycosylases, and AP endonuclease involved in the processing of glycosylase products, and their critical role in regulating repair functions. These disordered segments also include sites for posttranslational modifications and nuclear localization signal. The teleological basis for their structural flexibility is discussed.     

Solanum verrucosum as a base for mutation breeding in potato

Summary Solanum verrucosum Schlechtd, is proposed as a base for mutation breeding in potato. Its mutability was demonstrated with N-methyl-N-nitrosourea and N-ethyl-N-nitrosourea as mutagens.     

Kuhnian theory-choice and virtue convergence: Facing the base rate fallacy

Perhaps the strongest argument for scientific realism, the no-miracles-argument, has been said to commit the so-called base rate fallacy. The apparent elusiveness of the base rate of true theories has even been said to undermine the rationality of the entire realism debate. On the basis of the Kuhnian picture of theory choice, I confront this challenge by arguing that a theory is likely to be true if it possesses multiple theoretical virtues and is embraced by numerous scientists–even when the base rate converges to zero.