357 research outputs found
Evolutionary trends of Famennian icriodids in the Dinant and Vesdre basins (Conodonts, Belgian upper Devonian)
Two different probably depth- and/or facies-related morphological groups are recognized within the "shallow water" genus Icriodus of the Belgian Famennian: the "Icriodus alternatus group" dominates in the relatively quiet offshore marine sediments of the Lower Famennian ("Groupe des Schistes de la Famenne "), where as the "Icriodus cornutus-costatus group" characterizes the more nearshore, turbulent facies of the Upper-Famennian ("Groupe des Psammites du Condroz"). A probable endemic morphological evolution is suggested for the latter group. A phylomorphogenetical lineage has been observed between I. alternatus BRANSON & MEHL and I. cornutus SANNEMANN at the base of the Famennian. The interspecific morphological relations and the intraspecific morphological variability within the different Icriodus-stock are discussed. Three new morphotypes of I. alternatus, one new subspecies of I. cornutus and two new subsepcies of I. costatus (THOMAS) are described; their stratigraphical range is discussed
Sedimentary environments, conodont biofacies and paleoecology of the belgian Famennian (upper devonian) - an approach
The vertical succession of the sedimentary formations, which are diachronic with respect to the standard conodont and other microfossils zonation, represents a regressive megasequence in the Belgian Famennian, ranging from relatively deep, offshore open marine, shallow nearshore, to backshore restricted marine environments (THOREZ et al., 1977). Different associations of platform conodont form genera (Biofacies) reflect different ecological conditions, which are directly or indirectly related to water depth, turbulency, salinity and proximity to the coast ; from offshore to backshore we recognized successively a Palmatolepid, a Palmatolepid-Polygnathid, a Polygnathid-Icriodid, an Icriodid, and a supposed Clydagnathid biofacies. In this way the distribution pattern of conodont biofacies throughout the Famennian, represents a normal response to the oscillating movements of a prograding "coast" in the studied sedimentary basins. The presence moreover of mixed conodont biofacies (or thanatocoenoses) is also related to sedimentological processes, such as storm wave action, turbidity currents and tidal inlets
Fammenian
The name of the Famennian stage originated in the 19th century from the Famenne region in southern Belgium. After the pioneering work of Dumont, d'Omalius d'Halloy, Gosselet and Mourlon, a renewed interest in the 1960’s focused mainly on the lithological, sedimentological, paleontological and palynological characteristics of the Famennian. This resulted in a refined litho- and biostratigraphical framework for the Lower Famennian Famenne Shales and the Upper Famennian Condroz Sandstones in Belgium. The most obvious finding was the distinct diachronous character of the Condroz Group. The present review paper extends this stratigraphical framework into the neighbouring Avesnois (Northern France) and Aachen (Northwestern Germany) areas: it proposes a lithostratigraphical correlation between the units identified within the individual tectonic units. An overview is given of the main lithological-sedimentological characteristics, depositional environments (for both the siliciclastics and the carbonates) and prevailing paleogeographical-paloeclimatological conditions, during the Famennian stage in Belgium and adjacent areas
Recherches biostratigraphiques dans quelques coupes du Famennien de l'Avesnois (Nord de la France)
Conodonts and Goniatites from four "old" famennian sections in the Avesnois (France) have been carefully studies. For the first time, the biostratigraphic position of these sections is determined
The Devono-Carboniferous transition in the Franco-Belgian basin with reference to Foraminifera and Brachiopods
After a brief summary of the most striking evolutionary trends of the Upper Frasnian through Lower Tournaisian foraminifer assemblages in Northwestern Europe, some new biostratigraphic data are discussed mainly from an important section near St. Hilaire (Avesnois area, Northern France) as well as their impact on the problem of the Devono-Carboniferous boundary in the Franco-Belgian Basin
Odorous chemical perturbations of (Na+ + K+)-dependent ATPase activities. Effects on native and lipid-substituted preparations from individual turbinals from dog olfactory tissue
Infection with the gastrointestinal nematode Ostertagia ostertagi in cattle affects mucus biosynthesis in the abomasum
The mucus layer in the gastrointestinal (GI) tract is considered to be the first line of defense to the external environment. Alteration in mucus components has been reported to occur during intestinal nematode infection in ruminants, but the role of mucus in response to abomasal parasites remains largely unclear. The aim of the current study was to analyze the effects of an Ostertagia ostertagi infection on the abomasal mucus biosynthesis in cattle. Increased gene expression of MUC1, MUC6 and MUC20 was observed, while MUC5AC did not change during infection. Qualitative changes of mucins, related to sugar composition, were also observed. AB-PAS and HID-AB stainings highlighted a decrease in neutral and an increase in acidic mucins, throughout the infection. Several genes involved in mucin core structure synthesis, branching and oligomerization, such as GCNT3, GCNT4, A4GNT and protein disulphide isomerases were found to be upregulated. Increase in mucin fucosylation was observed using the lectin UEA-I and through the evaluation of fucosyltransferases gene expression levels. Finally, transcription levels of 2 trefoil factors, TFF1 and TFF3, which are co-expressed with mucins in the GI tract, were also found to be significantly upregulated in infected animals. Although the alterations in mucus biosynthesis started early during infection, the biggest effects were found when adult worms were present on the surface of the abomasal mucosa and are likely caused by the alterations in mucosal cell populations, characterized by hyperplasia of mucus secreting cells
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