Seasonal variation of androgen interconversion in testicular tissue ofRana temporaria in vitro

Summary Testicular steroid metabolism of winter and spring frogs,Rana temporaria, were studied by in vitro incubation with radioactively labelled dehydroepiandrosterone and androst-4-ene-3,17-dione. Marked seasonal differences were observed which are in line with the findings of others.     

A study of excitation-contraction coupling in frog tonic muscle fibers ofRana temporaria

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Some properties of crystalline inclusion bodies in oocytes ofRana temporaria andRana esculenta

Zusammenfassung Die drei in Oocyten vonRana temporaria undRana esculenta vorkommenden, kristallinen Einschlusskörper wurden mit Elektronenstrahl-Röntgen-Mikroanalyse und enzymatischer Verdauung am Dünnschnitt untersucht. Die hierbei erhaltenen Ergebnisse lassen auf eine unterschiedliche chemische Zusammensetzung der bis jetzt als Dotterplättchen bezeichneten Strukturen schliessen, was im Gegensatz zu bisherigen Annahmen steht.     

Spontaneous occurrence of aneuploidy in somatic cells ofRana tigrina (Ranidae: Anura)

Zusammenfassung Es wurde Aneuploidie bis zu drei Chromosomen in den männlichen Körperzellen vonRana tigrina (Ranidae: Anura: Amphibia) beobachtet. Die Variationen betreffen:2n–3, 2n–2, 2n–1, 2n, 2n+1, 2n+2 und2n+3.

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Acknowledgments. My sincere thanks are due to Dr.S. P. Sharma, Zoology Department, for facilities; to Mr.R. K. Pillai and MissMadhu for technical assistance with preparations and Drs.K. K. Rishi andL. K. Vats for helpful suggestions.     

The mechanism of tetrodotoxin on the in situ acetylcholinesterase in the vagal heart system ofRana pipiens

Zusammenfassung Am isolierten Vagus-Herzen vonRana pipiens wird die Wirkung der Vagusreizung gemessen: Konzentrationen unter 4×10^–10 g/ml Tetrodotoxin erhöhen die vagale Reizungswirkung, nicht aber die Herzkontraktionen.     

Abnormalities of meioses in male reciprocal hybrids between the Hiroshima and Ichinoseki populations ofRana japonica

In order to elucidate cytogenetically the cause of male sterility in intraspecific hybrids ofRana japonica, the behavior of chromosomes in the first meiosis was observed in spermatocytes from male reciprocal hybrids between two populations from Hiroshima and Ichinoseki. In the parental Hiroshima and Ichioseki populations, 2530 (96.7%) meiotic spreads had 13 bivalents and 78 (3.0%) contained 12 bivalents and two univalents, whereas in reciprocal hybrids only 337 (7.0%) contained 13 bivalents and the other 4445 (93.0%) had 2–26 univalents. A total of 31647 (93.4%) bivalents was ring-shaped and the other 2234 (6.6%) were rod-shaped in both parental populations, whereas in reciprocal hybrids 26352 (57.1%) and 19819 (42.9%) bivalents were ring- and rod-shaped, respectively. These results show that meiotic chromosomes of reciprocal hybrids are characterized by a remarkable increase in univalents and rod-shaped bivalents.     

Stimulation of dorsal axial differentiation in ventral explants ofRana pipiens embryos by CaCl2 and guanidine HCl

Résumé La culture de fragments isolés de mésoderme et d'ectoderme ventraux des gastrula de grenouilles (Rana pipiens) en présence de CaCl₂ 0,025–0.05M pendant un jour ou en présence de HCl guanidine 0,5% pendant un demi jour, et suivi d'une période de culture dans un salin physiologique induit une différentiation de tissus nerveux et musculaires dans 15 à 25% des cas. Des concentrations de CaCl₂ et de HCl guanidine pareilles à celle qui induit cette différentiation peuvent solubiliser des plaquettes vitellines isolés.     

Elemental distribution of Na,P, Cl and K in different structures of myelinated nerve ofRana esculenta

Summary Measurements of the distribution of Na, P, Cl and K were performed in different structures of the myelinated nerve. Whereas the axon shows a typical intracellular distribution pattern for Na, Cl and K, the interstitial space and the myelin sheath show a typical extracellular pattern. These measurements have demonstrated that Na is present in the myelin sheath close to the node of Ranvier.     

The role of the diffusible factor released by the egg jelly in fertilization of the toad egg

Resumen Los experimentes descritos indican que el factor difusible de las cubiertas gelatinosas de los ovocitos deBufo arenarum activaría a los espermatozoides a través de un efecto alcalinizante sobre el medio de inseminación.     

Presence of serum proteins in submaxillary duct perfusate

The secretory activity of the main excretory duct of rat submaxillary gland was investigated by the technique of luminal perfusion. Immunologic studies of the perfusate revealed the presence of serum antigens and the absence of intrinsic submaxillary gland antigens. It is suggested that the submaxillary duct permits passive transport of serum proteins to saliva from serum.     

Presence of serum proteins in submaxillary duct perfusate

Summary The secretory activity of the main excretory duct of rat submaxillary gland was investigated by the technique of luminal perfusion. Immunologic studies of the perfusate revealed the presence of serum antigens and the absence of intrinsic submaxillary gland antigens. It is suggested that the submaxillary duct permits passive transport of serum proteins to saliva from serum.     

Presence of viruses in a strain ofMycoplasma pulmonis

Summary Filtrates prepared from heavily grown agar cultures ofM. pulmonis strain Negroni-52 formed plaques on lawns ofA. laidlawii strain JA1 but not on those ofM. pulmonis strains Ash or Negroni-52. The plaque-forming agent proved to be rod-shaped particles morphologically identical with mycoplasmavirus group 1. Evidence supporting the conclusion that the virus originated from Negroni-52 has been obtained. Electron microscopy revelaed that Negroni-52 is also a carrier of long-tailed phage-like particles.