The transmission of tumours induced in cockroaches by nerve severance

Résumé On a obtenu des tumeurs dans des blattes (Periplaneta americana) après la section du nerf récurrent. Des extraits ou des filtrats de ces tumeurs, exempts de cellules, ont provoqué des lésions semblables quand on les a injectés à des adultes ou des nymphes.

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Part of the work was carried out during the tenure of a Commonwealth Visiting Professorship at the University of East Anglia and Visiting Professorship in the Department of Anatomy, Albert Einstein College of Medicine, Bronx (New York, USA).     

The structure of locomotor activity in bilobectomized cockroaches (Blaberus fuscus)

Summary The aperiodic activity patterns of bilobectomized cockroaches can largely be described by simple stochastic regularities: a) there are no correlations between the lengths of successive activity bursts and rest pauses, b) the probabilities for the transition from activity to rest and from rest to activity are time-independent. The activity sequence is strongly influenced by singular temperature steps or temperature cycles.     

Hormonal control of sexual receptivity in cockroaches

Many animals exhibit specific behaviors associated with sexual receptivity only when they are reproductively competent. In insects with gonadal maturation cycles, these behaviors usually coincide with ovarian matruation. In the cockroachBlattella germanica, juvenile hormone (JH), produced by the corpora allata (CA), regulates female reproductive physiology. Various experimental manipulations, including ablation of the CA, therapy with JH analogs, CA denervation, ovariectomy, and changing nutrient quality, coupled with time-lapse video recording, support the hypothesis that JH also controls female sexual receptivity. A re-examination of the role of the CA in the maturation of male sexual readiness shows that, while sexual behavior develops in the absence of JH in bothB. germanica andSupella longipalpa, JH accelerates the expression of sexual readiness.     

Protective action on mice of acellular extracts from Salmonella typhimurium]

Acellular fractions obtained by saline extraction at 60 or at 100 degree C of Salmonella typhimurium protect mice against an experimental infection with the homologous strain. After purification, these fractions which are complex, might be used for the development of a vaccine.     

Increased rate of melanization in hemolymph of American cockroaches (Periplaneta americana) and house crickets (Acheta domesticus) intoxicated by insecticides

Treatment of house crickets and American cockroaches with any one of a variety of insecticides increased the rate of melanization in hemolymph incubated with diphenol substrates.     

Increased rate of melanization in hemolymph of American cockroaches (Periplaneta americana) an house crickets (Acheta domesticus) intoxicated by insecticides

Summary Treatment of house crickets and American cockroaches with any one of a variety of insecticides increased the rate of melanization in hemolymph incubated with diphenol substrates.     

Regeneration of entire legs in cockroaches as a model for developmental events

Summary Young cockroach nymphs have the ability to generate entire legs which become the same size as normal legs when the animal is an adult. Studies of the physiological, structural and biochemical properties of some of the regenerated muscles suggest that these muscles are different from normal ones.     

Some new aspects of a sheep pineal gonadotropic inhibiting activity in in vitro experiments

Résumé Par des méthodes simples et bien déterminées: gelfiltration sur Sephadex G-25, G-10 et l'ultrafiltration par des diaflomembranes UM-02 et UM-05, on a pu isoler à partir d'un extrait aqueux d'épiphyses de mouton, des fractions capables d'inhiber l'activité gonadotrope hypophysaire. Cette activité inhibitrice a pu être localisée par l'électrophorèse sur papier. Les fractions ainsi obtenues sont capables d'inhiber in vitro l'excrétion hypophysaire de FSH et de LH.

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Acknowledgment. The authors gratefully acknowledge Dr. Reichert and Dr. Niswender for the generous supply of antigens and antibodies for the radioimmunoassay. Our thanks are also due to Mrs. A. E. M. Horwitz-Bresser for her skilful assistance in the isolation procedures.     

Role of intracellular symbionts in the fatbody of cockroaches: Influence on hemolymph proteins

Zusammenfassung Zur Herabsetzung der Anzahl von Symbionten in einem Fettkörper der KüchnschabeBlaberus craniifer wurde eine Penicillin-G-Behandlung durchgeführt, was eine Reduktion bei 2 Hämolymphe-Proteinen verursachte. Diese mit der Symbionten-Aktivität und Fortpflanzung verknüpften Proteine treten am Ende der Behandlung wieder in Erscheinung.     

The waking action of histamine

Zusammenfassung Die i.v. Infusion von 1 mg Histamin-2 HCl in 30 ml bei einer konstanten Strömung von 1 ml/min während 30 min führt zu einer statistisch signifikanten Abnahme der spontanen kortikalen Delta-Aktivität beim Kaninchen. Dieser elektrographische Weck-Parameter, der gleichzeitig mit einer Desynchronisierung des EEG einhergeht, ist bedeutend grösser bei Kaninchen, die Histamin erhalten haben, als bei Kontrolltieren. Die Weckreaktion dauert nach Ende der Infusion weitere 30 min an. Gleichzeitig bewirkt Histamin ein geringfügiges, nicht signifikantes Absinken des arteriellen Blutdruckes, eine Zunahme der Herzfrequenz sowie ein leichtes Ansteigen der Atmungsfrequenz. Aus diesen Befunden geht hervor, dass Histamin bei unwichtigen visceralen Auswirkungen bei der Regulierung des Wach-Schlaf-Zustandes eine Rolle spielen könnte.     

The action of cycloheximide on the action potential and protein synthesis in medullatedXenopus axons

Summary Cycloheximide depresses maximum rate of change in membrane potential observed during the rising phase of the action potential in single medullated axons ofXenopus. Time course of depression is independent of cycloheximide concentration over a range that almost completely inhibits leucine incorporation into axonal proteins.