Coexistence of neoteny and an internal cycle a polystomatid (Monogenea)]

Metapolystoma cachani a parasite of Ptychadena longirostris (Peters) has been discovered in the Ivory coast. Its life cycle is the first to involve both the possibility of an internal cycle in the bladder of the adult Amphibian and a neotenical reproduction on the gills of the Tadpole. This double process is the link between the Monogeneans which are only parasites of aquatic hosts and those which are adapted to terrestrial hosts. Its place is therefore essential in the phylogeny of Polystomatidae.     

Orientation of Giemsa C-bands in interphase cells of Allium cepa L.

Orientation of Giemsa C-bands in Allium cepa was studied in both mitotic and interphase cells. It has been shown that telophase orientation of the chromosome is maintained throughout the interphase and early phophase. It has been assumed that this non-random orientation is due to anchorage of the telomeres with the nuclear membrane. Contrary to earlier observations, 2 by 2 pairing of the telomers could not be traced to this species.     

Activité des N-acétyl-glucosaminyl-transférases microsomiques chez les souris BALB/c infectées par le virus de la tumeur mammaire murine (M-MTV)

Summary N-acetyl-glucosaminyl transferase in spleen cells of mice infected with M-MTV is enhanced. This increased synthesis of glycoprotein is not due to synthesis of new enzyme. Such a result suggest that the spleen is implicated in the infecting process.

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Ce travail fait partie d'une thèse de Doctorat ès-sciences préparée sous la direction de Madame le Docteur Jacqueline Mouriquand. Nous remercions le Professeur Pierre Louisot pour ses conseils fructueux dans la conduite de ce travail.     

Mutagenic effects of sulfur dioxide onSaccharomyces cerevisiae diploid strains

Summary In resting cells of diploidSaccharomyces cerevisiae strains sulfur dioxide induces at very high frequency: a) respiratory deficinet mutants: b) mutants with altered methionine metabolism. In growing cells the following kinds of mutants appear: a) revertants for respiration; b) mutants altered in the methionine metabolism; c) SO₂-resistants. It is suggested that sulfur dioxide acts as a selective agent through the induction SO₂-resistant mutantsAcknowledgments. This investigation was supported by grant of C.N.R., Roma. The authors are grateful to Prof. Domenico L. Palenzona for helpful comments and suggestions.     

Age dependency of the primary immune response in the hereditary pituitary dwarf and normal snell-bagg mouse

Riassunto Vengono riportati i dati relativi allo sviluppo in funzione dell'età, della reatività immunologica primaria nel topo con nanismo ereditario preipofisario e nel corrispondente fratello normale. Mentre in quest'ultimo si è notato un graduale incremento della reattività immunitaria di tipo primario soprattutto a partire dalla fine del periodo di allattamento, nel topo nano la reattività immunitaria primaria è rimasta costante nel tempo su bassi livelli anche dopo lo svezzamento. Alla luce dei dati sperimentali riportati viene ipotizzata l'esistenza di un controllo ipofisario della reattività immunitaria primaria.     

Urease. VIII. Its interaction with sodium dodecyl sulfate

Riassunto Il dodecilsolfato di sodio causa la dissociazione dell'urease (massa molecolare 480,000) in una maniera che dipende fortemente sulla concentrazione relativa dei reagenti. Il prodotto ottenuto con un sufficiente eccesso di detergente ha una massa molecolare di 50,000–60,000.

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This work was supported by Grant No. 11,573 and Career Award No. 5K3 GM 13,489 (to G.G.) from the National Institutes of Health, Department of Health, Education and Welfare.