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H. Van den Eynde

Bio: H. Van den Eynde is an academic researcher from University of Antwerp. The author has contributed to research in topics: Red algae & Fusobacterium nucleatum. The author has an hindex of 3, co-authored 4 publications receiving 31 citations.

Papers
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Journal ArticleDOI
TL;DR: Intraphylum relationships deduced from 5S rRNAs suggested that Bacteroides is specifically related to Cytophaga rather than to Fusobacterium, as was suggested by 16S rRNA analyses.
Abstract: The 5S ribosomal ribonucleic acid (rRNA) sequences were determined for Bacteroides fragilis, Bacteroides thetaiotaomicron, Bacteroides capillosus, Bacteroides veroralis, Porphyromonas gingivalis, Anaerorhabdus furcosus, Fusobacterium nucleatum, Fusobacterium mortiferum, and Fusobacterium varium. A dendrogram constructed by a clustering algorithm from these sequences, which were aligned with all other hitherto known eubacterial 5S rRNA sequences, showed differences as well as similarities with respect to results derived from 16S rRNA analyses. In the 5S rRNA dendrogram, Bacteroides clustered together with Cytophaga and Fusobacterium, as in 16S rRNA analyses. Intraphylum relationships deduced from 5S rRNAs suggested that Bacteroides is specifically related to Cytophaga rather than to Fusobacterium, as was suggested by 16S rRNA analyses. Previous taxonomic considerations concerning the genus Bacteroides, based on biochemical and physiological data, were confirmed by the 5S rRNA sequence analysis.

18 citations

Journal ArticleDOI
TL;DR: The accumulation of 5S RNA and tRNA in oocytes of Pleurodeles waltl is compared with the corresponding process previously studied in Xenopus laevis, finding that the storage function of the 7S particle protein (TFIIIA) is only marginal in this species.
Abstract: We have compared the accumulation of 5S RNA and tRNA in oocytes of Pleurodeles waltl with the corresponding process previously studied in Xenopus laevis. 5S RNA synthesis is regulated similarly in both species since different families of 5S RNA genes are transcribed in oocytes and in somatic cells of P. waltl, as in those of X. laevis. Previtellogenic oocytes of P. waltl contain only one prominent kind of storage particles (thesaurisomes). In contrast, X. laevis oocytes of the same size contain two major classes of thesaurisomes, sedimenting at 42S and 7S. The more abundant particles found in P. waltl oocytes are homologous to the larger thesaurisomes (42S) of X. laevis, but they have a lower sedimentation coefficient and a higher tRNA/5S RNA molar ratio than their X. laevis counterparts. Small amounts of particles which we think to be homologous to the 7S particles of X. laevis are present in previtellogenic oocytes of P. waltl. Therefore, the storage function of the 7S particle protein (TFIIIA) is only marginal in this species. In X. laevis oocytes TFIIIA has a second function. It acts as a positive transcription factor involved in the developmentally regulated expression of the 5S RNA genes. In X. laevis expression of the oocyte-type 5S RNA genes is accompanied by a massive accumulation of TFIIIA. This is not the case in P. waltl.

9 citations


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Journal ArticleDOI
TL;DR: With few exceptions, the 16 S rRNA data were in overall agreement with previously proposed reclassifications of species of Bacteroides, Prevotella, and Porphyromonas.
Abstract: The phylogenetic structure of the bacteroides subgroup of the cytophaga-flavobacter-bacteroides (CFB) phylum was examined by 16S rRNA sequence comparative analysis. Approximately 95% of the 16S rRNA sequence was determined for 36 representative strains of species of Prevotella, Bacteroides, and Porphyromonas and related species by a modified Sanger sequencing method. A phylogenetic tree was constructed from a corrected distance matrix by the neighbor-joining method, and the reliability of tree branching was established by bootstrap analysis. The bacteroides subgroup was divided primarily into three major phylogenetic clusters which contained most of the species examined. The first cluster, termed the prevotella cluster, was composed of 16 species of Prevotella, including P. melaninogenica, P. intermedia, P. nigrescens, and the ruminal species P. ruminicola. Two oral species, P. zoogleoformans and P. heparinolytica, which had been recently placed in the genus Prevotella, did not fall within the prevotella cluster. These two species and six species of Bacteroides, including the type species B. fragilis, formed the second cluster, termed the bacteroides cluster. The third cluster, termed the porphyromonas cluster, was divided into two subclusters. The first contained Porphyromonas gingivalis, P. endodontalis, P. asaccharolytica, P. circumdentaria, P. salivosa, [Bacteroides] levii (the brackets around genus are used to indicate that the species does not belong to the genus by the sensu stricto definition), and [Bacteroides] macacae, and the second subcluster contained [Bacteroides] forsythus and [Bacteroides] distasonis. [Bacteroides] splanchnicus fell just outside the three major clusters but still belonged within the bacteroides subgroup. With few exceptions, the 16 S rRNA data were in overall agreement with previously proposed reclassifications of species of Bacteroides, Prevotella, and Porphyromonas. Suggestions are made to accommodate those species which do not fit previous reclassification schemes.

219 citations

Journal ArticleDOI
TL;DR: On the basis of biochemical properties, phylogenetic position, DNA G+C content and DNA-DNA hybridization, it is proposed to unify Clostridium orbiscindens and Eubacterium plautii in a new genus as Flavonifractorplautii gen. nov., comb.
Abstract: We isolated several strains from various clinical samples (five samples of blood, four of intra-abdominal pus and one of infected soft tissue) that were anaerobic, motile or non-motile and Gram-positive rods. Some of the strains formed spores. Phylogenetic analysis of the 16S rRNA gene sequence showed that these organisms could be placed within clostridial cluster IV as defined by Collins et al. [(1994). Int J Syst Bacteriol 44, 812-826] and shared more than 99 % sequence similarity with Clostridium orbiscindens DSM 6740(T) and Eubacterium plautii DSM 4000(T). Together, they formed a distinct cluster, with Bacteroides capillosus ATCC 29799(T) branching off from this line of descent with sequence similarities of 97.1-97.4 %. The next nearest neighbours of these organisms were Clostridium viride, Oscillibacter valericigenes, Papillibacter cinnamivorans and Sporobacter termitidis, with sequence similarities to the respective type strains of 93.1-93.4, 91.2-91.4, 89.8-90 and 88.7-89.3 %. On the basis of biochemical properties, phylogenetic position, DNA G+C content and DNA-DNA hybridization, it is proposed to unify Clostridium orbiscindens and Eubacterium plautii in a new genus as Flavonifractor plautii gen. nov., comb. nov., with the type strain Prevot S1(T) (=ATCC 29863(T) =VPI 0310(T) =DSM 4000(T)), and to reassign Bacteroides capillosus to Pseudoflavonifractor capillosus gen. nov., comb. nov., with the type strain CCUG 15402A(T) (=ATCC 29799(T) =VPI R2-29-1(T)).

84 citations

Journal ArticleDOI
TL;DR: This paper summarizes recently published data on the structure and function of 5 S rRNA and its interactions in complexes with proteins, within and outside the ribosome.
Abstract: 5 S rRNA is an integral component of the large ribosomal subunit in all known organisms. Despite many years of intensive study, the function of 5 S rRNA in the ribosome remains unknown. Advances in the analysis of ribosome structure that have revealed the crystal structures of large ribosomal subunits and of the complete ribosome from various organisms put the results of studies on 5 S rRNA in a new perspective. This paper summarizes recently published data on the structure and function of 5 S rRNA and its interactions in complexes with proteins, within and outside the ribosome.

82 citations

Journal ArticleDOI
TL;DR: In this paper, the enzyme was solubilized with 2% Triton X-100 in 0.5M NaCl and purified 63fold to a specific activity of 870 nkat/mg by affinity chromatography on monomeric avidin-separharose.
Abstract: Membrane preparations of Fusobacterium nucleatum grown on glutamate contain glutaconyl-CoA decarboxylase at a high specific activity (13.8 nkat/mg protein). The enzyme was solubilized with 2% Triton X-100 in 0.5M NaCl and purified 63-fold to a specific activity of 870 nkat/mg by affinity chromatography on monomeric avidin-Sepharose. The activity of the decarboxylase was strictly dependent on Na+ (Km=3 mM) and was stimulated up to 3-fold by phospholipids. The glutaconyl-CoA decarboxylases from the gram-positive bacteria Acidaminococcus fermentans and Clostridium symbiosum have a lower apparent Km for Na+ (1 mM) and were not stimulated by phospholipids. In addition only the fusobacterial decarboxylase required sodium ion for stability and was inactivated by potassium ion. By incorporation of this purified enzyme into phospholipids an electrogenic sodium ion pump was reconstituted. The enzyme consists of four subunits,α (m=65 kDa), β (33 kDa), γ (19 kDa), and δ (16 kDa) with the functions of a carboxy transferase (α), a carboxy lyase (β and probably δ) and a biotin carrier (γ). The subunits are very similar to those of the glutaconyl-CoA decarboxylases from the gram-positive bacteria. With an antiserum directed against the decarboxylase from A. fermentans the α- and the biotin containing subunits of the three decarboxylases and that from Peptostreptoccus asaccharolyticus could be detected on Western blots.

72 citations

Book ChapterDOI
Sarah P. Gibbs1
01 Jan 1992
TL;DR: The present understanding of how chloroplasts evolved in the different groups of algae is summed up in this symposium presentation.
Abstract: The algae are not a natural assemblage of organisms Rather they are a diverse group of protists and fungi which have acquired chloroplasts in various ways, in some groups directly from symbiotic photosynthetic prokaryotes and in others from symbiotic eukaryotic algae The new techniques for rapidly sequencing ribosomal RNA, discussed by Adoutte in this volume, are producing evolutionary trees which are giving us a clearer understanding of the true relationships between different eukaryotes In Fig 1, I have drawn an evolutionary tree based on the sequences of the small subunit ribosomal RNA of a number of eukaryotes The most ancient eukaryotes whose ribosomal RNA has been sequenced to date are Giardia lamblia, a parasitic diplomonad, and Vairimorpha necatrix, a microsporidian Neither of these protists has mitochondria, and it is possible that these ancient eukaryotes evolved prior to the acquisition of mitochondria Also ancient are the trypanosomes and Euglena Somewhat later Dictyostelium evolved, but then came an explosive radiation of many protist groups, fungi, plants and animals In this tree, I have put in boldface lettering those groups which contain species with chloroplasts A glance at the tree shows that the algae are polyphyletic Euglenoids evolved very early and are related to trypanosomes The dinoflagellates, which many have assumed to be an ancient group because of the presence of a mesokaryotic nucleus (Loeblich, 1976), in fact evolved late and are related to ciliates The brown algae and Chrysophytes are related to each other and to the Oomycetes, a relationship long suspected due to the presence of heterokont flagella in each group Higher plants and green algae form a natural assemblage The fact that organisms with chloroplasts appear on different branches of the tree indicates that different groups have acquired chloroplasts independently of each other In this symposium presentation, I will summarize our present understanding of how chloroplasts evolved in the different groups of algae

68 citations