Unusual ultrastructural variants in the ferret parietal cell

Résumé On décrit deux rares variations structurelles: cristalloïdes cytoplasmiques intracellulaires et mitochondries géantes, observées dans les cellules marginals de la muqueuse gastrique du furet. Les cristalloïdes cytoplasmiques sont probablement en rapport avec la dégénération mitochondrielle, et les mitochondries géantes sont un caractère aberrant.     

Catecholamine biosynthesis in vascular tissue

Zusammenfassung Die Umwandlung von Tyrosin in Katecholamin wurde in verschiedenen Blutgefässen untersucht. Die Katecholamin-Biosynthese erfolgte am schnellsten in der Arteria mesenterica sup. (0,6 g/g/h), was zehnmal höher liegt als diejenige in der Aorta oder in der Arteria pulmonalis.     

Ultra-relativistic electrons in Jupiter's radiation belts

Ground-based observations have shown that Jupiter is a two-component source of microwave radio emission: thermal atmospheric emission and synchrotron emission from energetic electrons spiralling in Jupiter's magnetic field. Later in situ measurements confirmed the existence of Jupiter's high-energy electron-radiation belts, with evidence for electrons at energies up to 20[?]MeV. Although most radiation belt models predict electrons at higher energies, adiabatic diffusion theory can account only for energies up to around 20[?]MeV. Unambiguous evidence for more energetic electrons is lacking. Here we report observations of 13.8[?]GHz synchrotron emission that confirm the presence of electrons with energies up to 50[?]MeV; the data were collected during the Cassini fly-by of Jupiter. These energetic electrons may be repeatedly accelerated through an interaction with plasma waves, which can transfer energy into the electrons. Preliminary comparison of our data with model results suggests that electrons with energies of less than 20[?]MeV are more numerous than previously believed.     

Beitrag zur Kenntnis der Resistenzphänomene einzelner Pflanzen gegenüber dem phytotoxischen Wirkstoff Simazin

Summary 2,4-Dihydroxy-7-methoxy-1,4-benzoxazin-3-one (III), isolated from corn sap, detoxifies the herbicide Simazine, 2-chloro-4,6-bis-ethylamino-s-triazine,in vitro. 2,4-Dihydroxy-1,4-benzoxazin-3-one and the corresponding natural precursors of it and of (III), glucosides, behave in the same manner. It is very likely, therefore, that these glucosides and aglucones play a role in the resistance phenomena of some plant species against Simazine and related phytotoxic compounds. 6-Methoxybenzoxazolone and benzoxazolone, derived from the abovementioned benzoxazinones by heating, do not interfere with Simazine.     

The action of epinephrectomy on the toxicity of neomycin

Zusammenfassung Beiderseitige Exstirpation der Nebennieren vermindert die Toxizität von Neomycin undd-Tubocurarin.     

An asymptotic-giant-branch star in the progenitor system of a type Ia supernova

Stars that explode as supernovae come in two main classes. A type Ia supernova is recognized by the absence of hydrogen and the presence of elements such as silicon and sulphur in its spectrum; this class of supernova is thought to produce the majority of iron-peak elements in the Universe. They are also used as precise 'standard candles' to measure the distances to galaxies. While there is general agreement that a type Ia supernova is produced by an exploding white dwarf star, no progenitor system has ever been directly observed. Significant effort has gone into searching for circumstellar material to help discriminate between the possible kinds of progenitor systems, but no such material has hitherto been found associated with a type Ia supernova. Here we report the presence of strong hydrogen emission associated with the type Ia supernova SN2002ic, indicating the presence of large amounts of circumstellar material. We infer from this that the progenitor system contained a massive asymptotic-giant-branch star that lost several solar masses of hydrogen-rich gas before the supernova explosion.