AfrOBIS: a marine biogeographic information system for sub-Saharan Africa

AfrOBIS is one of 11 global nodes of the Ocean Biogeographic Information System (OBIS), a freely accessible network of databases collating marine data in support of the Census of Marine Life. Versatile graphic products, provided by OBIS, can be used to display the data. To date, AfrOBIS has loaded about3.2 million records of more than 23 000 species located mainly in the seas around southern Africa. This forms part of the 13.2 million records of more than 80 000 species currently stored in OBIS. Scouting for South African data has been successful, whereas locating records in other African countries has been much less so

Regulation of the pyruvate kinase from Alcaligenes eutrophus H 16 <em>in vitro</em> and<em> in vivo</em>.

The biosynthesis of the enzyme pyruvate kinase (E.C. 2.7.1.40) of Alcaligenes eutrophus (Hydrogenomonas eutropha) H 16 was influenced by the carbon and energy source. After growth on gluconate the specific enzyme activity was high while acetate grown cells exhibited lower activities (340 and 55 &mu;moles/min&middot;g protein, respectively). The pyruvate kinase from autotrophically grown cells was purified 110-fold. The enzyme was characterized by homotropic cooperative interactions with the substrate phosphoenolpyruvate, the activators AMP, ribose-5-phosphate, glucose-6-phosphate and the inhibitor ortho-phosphate. In addition to phosphate ATP caused inhibition but in this case non-sigmoidal kinetics was obtained. The half maximal substrate saturation constant S0.5 for phosphoenolpyruvate in the absence of any effectors was 0.12 mM, in the presence of 1 mM ribose-5-phosphate 0.07 mM, and with 9 mM phosphate 0.67 mM. The corresponding Hill values were 0.96, 1.1 and 2.75. The ADP saturation curve was hyperbolic even in the presence of the effectors, the Kmvalue was 0.14 mM ADP. When the known intracellular metabolite concentrations in A. eutrophus H 16 were compared with the regulatory sensitivity of the enzyme, it appeared that under the conditions in vivo the inhibition by ATP was more important than the regulation by the allosteric effectors

The Upper Bajocian and Bathonian in the Cordillera de Domeyko, North-Chilean Precordillera : sedimentological and biostratigraphical results.

The Jurassic ammonites of the Cordillera de Domeyko have been studied in several monographies. The classic memoirs of Steinmann (1881), Tornquist (1898), Burckhardt (1903) and Stehn (1923) are particularly relevant. However, the biostratigraphic problems concerning stage boundaries arisen only in recent dates. New sedimentological and biostratigraphical data have been obtained in relation to the Bajocian/Bathonian of this region. Several sections have been studied in two separate areas : Caracoles and Sierra de Varas. More than one thousand ammonites were collected in situ from these localities. Facies analysis shows that sedimentation during Late Bajocian and Bathonian occurs in a marine environment on a carbonate platform with abundant siliciclastic supply. Facies distribution was controlled by structural segmentation of the platform and processes of differential subsidence. The stratigraphical-sedimentological results together with taphonomical-palaeoecological observations are a diagnostic tool for sequence analysis. The successive ammonite assemblages which were found have allowed the establishment of four biostratigraphic units, spanning the interval from Upper Bajocian to Upper Bathonian. The sedimentological and biostratigraphical results indicate the existence of a regional discontinuity at the base of the Bathonian

Transfer of the nitrogen fixing hydrogen bacterium <em>Corynebacterium autotrophicum</em> Baumgarten et al. to <em>Xanthobacte</em>r gen. nov.

Thirty-five nitrogen-fixing, hydrogen-oxidizing bacteria, all members of Cory-nebacterium autotrophicum Baumgarten, Reh, and Schlegel 1974, and including the type strain of this species, were compared with 28 strains of coryneform bacteria by numerical taxonomy methods. The nitrogen-fixing hydrogen bacteria formed a well defined cluster; their similarity to the other strains tested was low, however. Furthermore, the chemotaxonomic characters of these strains excluded them from the coryneform bacteria. Therefore C. autotrophicum was reclassified, following the keys of Bergey&#39;s Manual of Determinative Bacteriology (8th ed.) as a species of the family Azotobacteraceae. Although taxonomically close to Beijerinckia and Derxia, the nitrogen-fixing, hydrogen-oxidizing bacteria are regarded as representing a new genus, for which we propose the name Xanthobacter. C. autotrophicum Baumgarten, Reh, and Schlegel is transferred to the new genus as Xanthobacter autotrophicus (Baumgarten et al.) comb. nov

Proterozoic-Paleozoic development of the basement of the Central Andes (18-26°S) - A mobile belt of the South American craton

The Late Precambrian-Early Paleozoic metamorphic basement forms a volumetrically important part of the Andean crust. We investigated its evolution in order to subdivide the area between 18 and 26°S into crustal domains by means of petrological and age data (Sm-Nd isochrons, K-Ar). The metamorphic crystallization ages and tDM ages are not consistent with growth of the Pacific margin north of the Argentine Precordillera by accretion of exotic terranes, but favor a model of a mobile belt of the Pampean Cycle. Peak metamorphic conditions in all scattered outcrop areas between 18 and 26°S are similar and reached the upper amphibolite facies conditions indicated by mineral paragensis and the occurrence of migmatite. Sm-Nd mineral isochrons yielded 525 ± 10,505 ± 6 and 509 ± 1 Ma for the Chilean Coast Range, the Chilean Precordillera and the Argentine Puna, and 442 ± 9 and 412 ± 18 Ma for the Sierras Pampeanas. Conventional K-Ar cooling age data of amphibole and mica cluster around 400 Ma, but are frequently reset by Late Paleozoic and Jurassic magmatism. Final exhumation of the Early Paleozoic orogen is confirmed by Devonian erosional unconformities. Sm-Nd depleted mantle model ages of felsic rocks from the metamorphic basement range from 1.4 to 2.2 Ga, in northern Chile the average is 1.65 ± 0.16 Ga (1σ, n = 12), average tDM of both gneiss and metabasite in NW Argentina is 1.76 ± 0.4 Ga (1σ, n = 22), and the isotopic composition excludes major addition of juvenile mantle derived material during the Early Paleozoic metamorphic and magmatic cycle. These new data indicate a largely similar development of the metamorphic basement south of the Arequipa Massif at 18°S and north of the Argentine Precordillera at 28°S. Variations of metamorphic grade and of ages of peak metamorphism are of local importance. The protolith was derived from Early to Middle Proterozoic cratonic areas, similar to the Proterozoic rocks from the Arequipa Massif, which had undergone Grenvillian metamorphism at ca. 1.0 Ga.Fil: Lucassen, F.. Technishe Universitat Berlin; AlemaniaFil: Becchio, Raul Alberto. Technishe Universitat Berlin; Alemania. Universidad Nacional de Salta; ArgentinaFil: Wilke, H.G.. Universidad Catolica del Norte; ChileFil: Franz, G.. Technishe Universitat Berlin; AlemaniaFil: Thirlwall, M.F.. University of London; Reino UnidoFil: Viramonte, Jose German. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Wemmer, K.. Institut Für Geologie Und Dynamik Der Lithosphäre

Géodynamique andine : résumé étendus = Andean geodynamics : extended abstracts

Un métamorphisme de haut grade, haute température (600-750°C) et basse pression (environ 6kb) est observé dans différents sites depuis le NW de l'Argentine jusqu'à la chaîne côtière du nord Chili, avec des âges Sm-Nd de paroxysme métamorphique à 500 Ma. Les âges K-Ar sur minéraux indiquent un refroidissement des roches métamorphiques autour de 400 Ma. L'exhumation finale a eu lieu jusqu'au Carbonifère. Le degré de métamorphisme, la déformation et les relations d'âge montrent un évènement métamorphique avec un fort flux de chaleur au niveau de la croûte moyenne. Ceci n'est pas en accord avec un développement de la marge continentale, à la fin du Protérozoïque et au Paléozoïque, par un système multi-cycles "collision-ouverture de rifts". (Résumé d'auteur

Das Hochwasser 1993/94 im Rheingebiet

SIGLEAvailable from TIB Hannover: RN 4055(833) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman