Propriétés chitinolytiques du liquide exuvial du ver à soie (Bombyx mori L.)

Summary The authors add further confirmation to the hypothesis of the role played by a chitinase during the process of moulting. By ligaturingBombyx mori-larvae between head and thorax, accumulation of moulting fluid takes place between the larval and nymphal cuticles, swallowing of this fluid being prevented. The chitinolytic properties of this moulting fluid are demonstratedin vitro. The activity of chitinase at different pH is investigated: the optimum pH lying at about 5.4.     

Additional studies on the effects of neonatal thymectomy and lactate dehydrogenase virus infection on mice

Zusammenfassung Die gegebenen Befunde lassen vermuten, dass neonatale Thymektomie und/oder Infektion mit LDH-Virus einen Effekt auf eine Anzahl von Faktoren wie LDH-Plasma-Spiegel, Gewichtserhöhung und Lebensdauer in Mäusen hervorrufen können. Der Virustiter im Plasma ist vom Zeitpunkt der Infektion abhängig.

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Supported by Public Health Service research grant No. 5 R01 CA05742-06 from the National Cancer Institute.     

Morphogenetic effect of precocene I and II onSchistocerca gregaria (Forsk)

Summary 4th instar nymphs ofSchistocerca gregaria exposed to precocene I and II by topical application metamorphosed precociously. The ED₅₀ of both compounds were evaluated and, unexpectedly, precocene I was found to be more active than precocene II. All adultiforms were identical and in an advanced form.Acknowledgments. This work was supported by grants from the Natural Sciences and Engineering Research Council of Canada and the Ministère de l'Education du Québec. We are grateful to Gaston Grégoire for rearing the insects.     

The somatic chromosomes of 3 lizard species:Gekko gecko,Iguana iguana,andCrotaphytus collaris

Zusammenfassung Die somatischen Chromosomen der 3 EidechsenartenGekko gecko (2N=38),Iguana iguana (2N=34) undCrotophytus collaris (2N=36), werden dargestellt.G. gecko besitzt metazentrische, subteleozentrische und teleozentrische Elemente, aber keine Mikrochromosomen.I. iguana undC. collaris besitzen Makrochromosomen (6 Paare) und Mikrochromosomen. Bei den ArtenG. gecko undI. iguana waren in keinen von beiden Geschlechtern heteromorphische Chromosomenpaare nach zuweisen.

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Supported by Project No. 417 from the U.S. Children's Bureau and Grant No. 08737 from the National Cancer Institute.     

Technique d'inclusion et d'ultramicrotomie,destinée à l'étude du développement des organelles dans une cellule isolée

Summary (1) Control of cell orientation and knowledge of the plane of sectioning are indispensable (but generally ignored) requirements for studies of the development of cellular constituents. (2) A simple technique that meets these requirements for the electron microscope is given. (3) As applied toParamecium, it is shown that the ciliary complexes of the new gullet develop outside of the old one, and that invagination begins at the anterior end of the gullet anlage.

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Travail effectué dans le cadre d'une recherche faite en collaboration avec les Instituts d'Histologie et de Biophysique, grâce à une subvention de «Fritz Hoffmann-La Roche-Stiftung zur Förderung wissenschaftlicher Arbeitsgemeinschaften in der Schweiz».     

Cytological demonstration of female heterogamety in isopods

Résumé Des chromosomes sexuels, inconnus jusqu'à présent chez les Isopodes, ont été trouvés dans 4 espèces de la superespèceJaera marina (Janiridae, Asellota). Il s'agit d'un système multiple de chromosomes sexuels, ce qui aboutit à la formation d'un trivalent sexuel dans la méiose femelle. Les femelles — hétérogamétiques — ont la constitution XY₁Y₂, les mâles étant XX. D'après les données chromosomiques présentées par les 4 espèces étudiées, la formation du système multiple sexuel est due à des processus cytologiques évolutifs d'ordre Robertsonien.

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Aided by a grant from the Janggen Pöhn Foundation (St. Gallen, Switzerland) and supported by the Swiss Commission for the Biological Station of Roscoff.     

Ultrasonic vocalizations by adult prairie voles,Microtus ochrogaster

Summary Male and femaleMicrotus ochrogaster were presented with anesthetized and awake conspecifics while ultrasonic vocalizations (USVs) were monitored. Males produced significantly more USVs than females during 5-min testing sessions. Males tended to produce more USVs to unfamiliar females than to familiar female siblings. Sexual experience led to increased USV scores by males. These results suggest that USVs by male prairie voles communicate to females the male's gender and his availability for reproductive behavior.     

Somesthetic cortex reactivity during sleeping and waking in the rat

Summary The cortical S1 responsiveness was studied by unique and coupled stimuli of non-maximal intensity applied to somesthetic radiations. The reactivity is highest during sleep with slow waves, lowest during active waking, intermediate during non-active waking and rapid sleep. The recovery of responsiveness presents an exactly opposite form and begins at a long interstimulus delay (>150 msec).     

Preparation of lymphocytes from small volumes of peripheral mouse blood

Summary A method was developed which allowed for the isolation of lymphocytes (95% of leukocytes in the final suspensions) from small volumes of peripheral mouse blood (38% recovery). The method proved of value for studies of murine lymphocytes which required biochemical analysis of samples from individual animals on a serial basis.This work was supported in part by a University College Faculty Research Grant.