Some structural features of isolated mitochondrial membranes

Zusammenfassung Isolierte Membranen von Mitochondrien (Ratte) wurden mit Kaliumpermanganat fixiert, mit Ultraschall behandelt und dann bedampft. Elektronenmikroskopische Aufnahmen zeigen eine granuläre Struktur und gelegentlich auch Fasern. Diese Ergebnisse sind im Einklang mit denen einiger anderer Autoren.     

Homology of arthropod anterior appendages revealed by Hox gene expression in a sea spider

Arthropod head segments offer a paradigm for understanding the diversification of form during evolution, as a variety of morphologically diverse appendages have arisen from them. There has been long-running controversy, however, concerning which head appendages are homologous among arthropods, and from which ancestral arrangement they have been derived. This controversy has recently been rekindled by the proposition that the probable ancestral arrangement, with appendages on the first head segment, has not been lost in all extant arthropods as previously thought, but has been retained in the pycnogonids, or sea spiders. This proposal was based on the neuroanatomical analysis of larvae from the sea spider Anoplodactylus sp., and suggested that the most anterior pair of appendages, the chelifores, are innervated from the first part of the brain, the protocerebrum. Our examination of Hox gene expression in another sea spider, Endeis spinosa, refutes this hypothesis. The anterior boundaries of Hox gene expression domains place the chelifore appendages as clearly belonging to the second head segment, innervated from the second part of the brain, the deutocerebrum. The deutocerebrum must have been secondarily displaced towards the protocerebrum in pycnogonid ancestors. As anterior-most appendages are also deutocerebral in the other two arthropod groups, the Euchelicerata and the Mandibulata, we conclude that the protocerebral appendages have been lost in all extant arthropods.     

Spatial coupling of nitrogen inputs and losses in the ocean

Nitrogen fixation is crucial for maintaining biological productivity in the oceans, because it replaces the biologically available nitrogen that is lost through denitrification. But, owing to its temporal and spatial variability, the global distribution of marine nitrogen fixation is difficult to determine from direct shipboard measurements. This uncertainty limits our understanding of the factors that influence nitrogen fixation, which may include iron, nitrogen-to-phosphorus ratios, and physical conditions such as temperature. Here we determine nitrogen fixation rates in the world's oceans through their impact on nitrate and phosphate concentrations in surface waters, using an ocean circulation model. Our results indicate that nitrogen fixation rates are highest in the Pacific Ocean, where water column denitrification rates are high but the rate of atmospheric iron deposition is low. We conclude that oceanic nitrogen fixation is closely tied to the generation of nitrogen-deficient waters in denitrification zones, supporting the view that nitrogen fixation stabilizes the oceanic inventory of fixed nitrogen over time.     

Etude préliminaire des Halos Pléochroïques de quelques Roches métamorphiques et éruptives du St-Gothard

Zusammenfassung Die Untersuchung der pleochroitischen Höfe der Biotite in Orthogneisen, Paragneisen und Bündnerschiefern des südlichen Gotthardmassives ergab durchwegs ein ähnliches Alter, nämlich < 60 Millionen Jahre. Es bedeutet dies, dass eventuell vorhandene vortertiäre Höfe in prätriadischen Biotiten der Gneise während der alpinen Metamorphose fast oder ganz durch Rekristallisation zerstört worden sind.     

Intrarenal redistribution of the organ blood flow,induced by bleeding or hemorrhagic shock

Zusammenfassung Es wird eine durch Blutung und hämorrhagischen Schock hervorgerufene intrarenale Neuverteilung der Durchblutung beschrieben. Der wesentliche Effekt ist eine verminderte Blutversorgung der äussern Markzone.     

Age des halos pléochroïques de quelques granites tertiaires de la Toscane

Riassunto Sono stati studiati gli aloni dei graniti delle isole di Montecristo e del Giglio (arcipelago toscano) e del continente (Gavorrano).Tale studio ha permesso di dimostrare che il loro consolidamento è avvenuto in momenti diversi la cui successione ripete quella dei corrugamenti appenninici. Le età di tali graniti, comparate a quella dell'Elba (Monte Capanne), sono nel seguente ordine:Elba = Montecristo > Giglio > Gavorrano.I singoli stadi sono largamente spaziati nel tempo e gli intervalli sono risultati dell'ordine di circa dieci millioni di anni.

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Attachée à l'Institut Interuniversitaire des Sciences Nucléaires.

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Comitato Nazionale per le Ricerche Nucleari.