Considerations Paléogéographiques déduites de l’étude des Foraminifères des couches de passage du Viséen au Namurien (Bassins de Reggane et de Fort-Polignac, Sahara Central.)

The foraminiferal microfauna of the Visean Tethys is identical to that of the Gondwanian craton of North Africa, but differs from that of the Appalachian realm. This distribution contradicts the hypothesis of contiguity between Eurafrica and North America during the Carboniferous

Microfacies d’une lentille biohermale a la limite Eifelien/Givetien (Wellin, bord sud du synclinorium de Dinant)

A biohermal lens is described from the Eifelian-Givetian transition beds near Wellin (southern flank of the Dinant basin). The lens is about 200 m long and 45 m thick. It is composed of a central stromatopore-coral framestone (30 m) and of flanks of udoteacean packstone and stromatopore-brachiopod floatstone. The sedimentology based on two nearby sections indicate a regression. The log is based on the succession of 10 carbonate microfacies (MF1-10, standard sequence). The deepest microfacies (MF1) is open marine at the upper limit of the storm waves and the dysphotic-euphotic boundary. The shallower microfacies is partly emerged (lagoonal sediments, MF10). The framestone (MF7) is characterized by early isopachous cementation. Communities and fossil assemblages underline the important development of udoteacean meadows in the flanks while these algae play little or no role in the formation of the framestone. The bioherm covers a crinoidal sole (MF4), that is overlying the open marine facies (MF1-3). These show evidence of sulfate-reduction, with widespread bacterial (?) filamentous pyrite. Correlation between the two stratigraphic sections indicates that the architecture of the bioherm (central core and flanks) is planar (‘bank »). The total thickness of the studied succession is about 70 m. They grade from dysphotic-euphotic boundary estimated here around 20 m deep to emersion. Thus subsidence is here much more important than the eustatic regression. A new green udoteacean alga is described : Vignella nilsii n.gen., n. sp

Le Calcaire de Givetien à Givet

The authors recount the original definitions and the evolution of the conceptions of the Giuet Limestone and the Givetian at Givet. In order to end the existing confusion they define a Givet Group composed of three formations, which are, from base to top : Trois-Fontaines, Mont d'Haurs and Fromelennes Formations.Each of these formations corresponds to a third order positive-negative bisequence (marine facies - sabkha - marine facies), while second order sequences permit the recognition of thirty-two major phases which indicate the following environments : detrital and non-turbulent in the euphotic zone, reef, lagoon and of sabkha; minor first order sequences are recognized in those major phases.As for the Givetian, the authors make suggestions to be eventually examined by international bodie

Algues Viséennes du sondage de Turnhout (Campine, Belgique)

The article describes twenty-five algae, mostly green algae (dasycladaceans and codiaceans) observed in the Visean carbonates of the Turnhout borehole. Two species are new: Orthriosiphon turnhouti and Atractyliopsis weyanti</i

Sédimentologie des faciès “Marbres Noirs” du paléozoïque franco-belge

This study works out the sedimentation of upper paleozoic formations of Belgium and northern France.It deals with sequential analysis of calcareous facies, more particularily, the so-called « black marbles »; it is possible to recognize a number of « rythmic patterns » which can be followed laterally from quarry to quarry. These « rhythms » have chronostratigraphic value; coupled with local markers, they enable the building of an extremely precise paleogeography.The petrographic investigation of the strata of « black marbles » leads to a more general classification of limestones in which the type of cement and the proportions of the different calcareous debris (allochems) arc the main variables.Ecologie studies on the relative distribution of macro- and niicrofauna show the faunal assemblage to be dominated by biocenic influences. « Black marbles » are neither characteristically rich in plankton, nor deposited in sulfuric environments; they are characterized by the thinness and uniformity of the calcite grains and by a reducing Eh at the sedimentation time

Microfaciès d’une lentille biohermale a la limite Eifelien/Givetien (‘Fondry Des Chiens’, Nismes, bord sud du synclinorium de Dinant)

Microfacies of a biohermal lens at the Eifelian.Givetian transition (‘Fondry des Chiens’, Nismes, southern border of the Dinant Synclinorium). The biohermal lens of the ‘Fondry des Chiens’ belongs to the Eifelian-Givetian transition beds near Nismes (southern flank of the Dinant basin). The lens is 64 m thick and composed of a stromatopore-coral framestone. It is overlain by restricted lagoonal algal and cyanophycean facies near the emersion, and overlies Udoteacean and coral-bryozoan coverstones forming the flanks of two other unexposed lenses. Two crinoidal soles stabilized by syntaxial cementation constitute the substratum of these lenses. The reefal sedimentation is regressive. The log is based on the succession of 10 carbonate microfacies (MF1-10, standard sequence). The deepest microfacies (MF1) is open marine at the upper limit of the storm waves and the dysphotic-euphotic boundary. The shallowest sediments were partly emerged (lagoonal sediments, MF10). The exposed reefal lens (rudstones and framestones, MF6-7) and the flanks (grainstones, floatstones and coverstones, MF3-4-5) of the two other lenses are preserved due to early isopachous intergranular cement in the original cavities of the framestones or ‘intramicritic’ (replacement of the matrix) cementation in the floatstones and coverstones. The similarity of the facies and their algal content suggest that the sedimentary model proposed at Wellin is applicable at Nismes. Sequential analysis points to a three steps regressive evolution of the sedimentation probably related to a discontinuous subidence. The sequences have similar thicknesses (sixty or so meters) and grade from the dysphotic-euphotic boundary estimated here around twenty meters deep to emersion. As for Wellin, the subsidence is thus much more important than the eustatic regression

Marine Carboniferous algae from metacarbonates of the Ochtina Formation(Gemeric Unit, Western Carpathians)

An association of eight taxons of marine algae is described from the anchimetamorphosed dolomites of Late Visean-Namurian A aged The algae confirm this determination of age based preciously on conodonts. The flora is indicative of latest Viscan Zone 16 to Early, Serpukhovian Zone 17. The microfossils from the locality Furmanec are somewhat older, indicative of Late Viscan (Zone 15 to 16?)

Action des sulfonates d'éthyle et de méthyle méthane sur l'injection d'ADN et la recombinaison génétique dans le bactériophage T7.

peer reviewedAfter treatment with methyl or ethyl methane sulfonate, T7 amber mutants display a reduced capacity for recombination. Moreover, alkylation reduces recombination frequency involving markers on the right-hand side of the genetic map more than it reduces recombination frequency involving markers on the left-hand side. We interpret this to mean that alkylation can stop DNA injection at any point along the DNA molecule, and that T7 phage injects its DNA in a unique fashion starting from the end carrying the genes for early proteins

Prognostic value of clinicopathological parameters in head and neck squamous cell carcinoma: a prospective analysis.

The prognostic weight of histological and biological factors was compared with that of known clinical prognostic factors in a population of 108 consecutive previously untreated patients with head and neck squamous cell carcinoma. Parameters studied were: tumour vascularisation, mitotic index, histological differentiation, nuclear grade, keratinisation, desmoplasia, growth pattern, inflammation, tumour emboli in peripheral vessels, keratins 6, 13, 19 immunohistochemical expression, cytofluorometric ploidy and S-phase. In multivariate analysis (Cox), only age and nodal status had a significant impact on the overall survival, whereas T stage was the only significant factor associated with locoregional failure. The cumulative incidence of metastases was correlated not only with age, T and N stage, but also with histological differentiation. All the other histological and biological factors studied failed to provide further prognostic information. These findings may help to select patients with high metastatic risk

Beneficial plant-microbial interactions in agroecosystems: deciphering the rhizosphere microbial community in two field grown crops

Non-Peer Reviewe