2,771 research outputs found
Evaluating the Evolutionary Origins of Unexpected Character Distributions within the Bacterial Planctomycetes-Verrucomicrobia-Chlamydiae Superphylum
Recently, several characters that are absent from most bacteria, but which are found in many eukaryotes or archaea, have been identified within the bacterial Planctomycetes-Verrucomicrobia-Chlamydiae (PVC) superphylum. Hypotheses of the evolutionary history of such characters are commonly based on the inference of phylogenies of gene or protein families associated with the traits, estimated from multiple sequence alignments (MSAs). So far, studies of this kind have focused on the distribution of (i) two genes involved in the synthesis of sterol, (ii) tubulin genes, and (iii) c1 transfer genes. In many cases, these analyses have concluded that horizontal gene transfer (HGT) is likely to have played a role in shaping the taxonomic distribution of these gene families. In this article, we describe several issues with the inference of HGT from such analyses, in particular concerning the considerable uncertainty associated with our estimation of both gene family phylogenies (especially those containing ancient lineage divergences) and the Tree of Life (ToL), and the need for wider use and further development of explicit probabilistic models to compare hypotheses of vertical and horizontal genetic transmission. We suggest that data which is often taken as evidence for the occurrence of ancient HGT events may not be as convincing as is commonly described, and consideration of alternative theories is recommended. While focusing on analyses including PVCs, this discussion is also relevant for inferences of HGT involving other groups of organisms
Bijzondere broedvogels in Vlaanderen in de periode 1994-2005; Populatietrends en recente status van zeldzame, kolonievormende en exotische broedvogels in Vlaanderen
Detection of genetically modified plant products by protein strip testing: an evaluation of real-life samples
The determination of the presence of genetically modified plant material by the detection of expressed genetically engineered proteins using lateral flow protein strip tests has been evaluated in different matrices. The presence of five major genetically engineered proteins (CP4-EPSPS, CryIAb, Cry9C, PAT/pat and PAT/bar protein) was detected at low levels in seeds, seed/leaf powder and leaf tissue from genetically modified soy, maize or oilseed rape. A comparison between "protein strip test" (PST) and "polymerase chain reaction" (PCR) analysis of genetically modified food/feed samples demonstrates complementarities of both techniques. -ÂŽ Springer-Verlag 2007</p
The role of geomorphic controls on the development of defensive networks along the Western Front during the Great War: case study of Champagne and Argonne (france)
The Great War was marked on the western front mainly by a war of position (for 40 out of the 51 months of the conflict) along the 750 km of the front area from Flanders to Alsace. The objective of this article is to understand the spatial organisation of defence networks in the eastern part of the Champagne region (Champagne sèche), the Vallage dâAisne and in the Argonne region in 1918 by means of an analysis of geographical information system (GIS)-processed trench maps. This article presents a methodology, involving the transfer of fire trenches, communication trenches and vegetation, integrated into a geodatabase, and then cross-referenced with the digital terrain model (DTM). This comparison of three distinct regions with a chalky plateau (Champagne sèche), a wet plain (Vallage dâAisne) and a sandy plateau covered with forests (Argonne), not only makes it possible to qualify the role of geographical conditions on the Great War but also to quantify the defence networks.Keywords: WW1, trench map, GIS, spatial analysis, Champagne sèche, Vallage dâAisne, Argonn
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