Biomedical subjects

Gaetan Borgonie

Publications and source records attributed to Gaetan Borgonie.

5 recordsLinked to original sources

PubMed2006

An improved molecular phylogeny of the Nematoda with special emphasis on marine taxa.

Phylogenetic reconstructions of relations within the phylum Nematoda are inherently difficult but have been advanced with the introduction of large-scale molecular-based techniques. However, the most recent revisions were heavily biased towards terrestrial and parasitic species and greater representation of clades containing marine species (e.g. Araeolaimida, Chromadorida, Desmodorida, Desmoscolecida, Enoplida, and Monhysterida) is needed for accurate coverage of known taxonomic diversity. We now add small subunit ribosomal DNA (SSU rDNA) sequences for 100 previously un-sequenced species of nematodes, including 46 marine taxa. SSU rDNA sequences for >200 taxa have been analysed based on Bayesian inference and LogDet-transformed distances. The resulting phylogenies provide support for (i) the re-classification of the Secernentea as the order Rhabditida that derived from a common ancestor of chromadorean orders Araeolaimida, Chromadorida, Desmodorida, Desmoscolecida, and Monhysterida and (ii) the position of Bunonema close to the Diplogasteroidea in the Rhabditina. Other, previously controversial relationships can now be resolved more clearly: (a) Alaimus, Campydora, and Trischistoma belong in the Enoplida, (b) Isolaimium is placed basally to a big clade containing the Axonolaimidae, Plectidae, and Rhabditida, (c) Xyzzors belongs in the Desmodoridae, (d) Comesomatidae and Cyartonema belongs in the Monhysterida, (e) Globodera belongs in the Hoplolaimidae and (f) Paratylenchus dianeae belongs in the Criconematoidea. However, the SSU gene did not provide significant support for the class Chromadoria or clear evidence for the relationship between the three classes, Enoplia, Dorylaimia, and Chromadoria. Furthermore, across the whole phylum, the phylogenetically informative characters of the SSU gene are not informative in a parsimony analysis, highlighting the short-comings of the parsimony method for large-scale phylogenetic modelling.

Animals↗

PubMed2004

An SXP/RAL-2 protein produced by the subventral pharyngeal glands in the plant parasitic root-knot nematode Meloidogyne incognita.

Meloidogyne incognita is a major parasite of numerous plant families, including many crop species. Upon infection of the plant root, it induces several multinucleate giant cells by the injection of pharyngeal gland secretions into the root cells. In order to obtain a better understanding of the nematode-plant interaction, characterization of the pharyngeal gland secretions is a necessity. By differential display, a nematode gene was identified that encodes a new member of the SXP/RAL-2 protein family. The gene is specifically expressed in the subventral pharyngeal glands and the protein is most likely secreted.

Amino Acid Sequence↗

PubMed2004

The apical disposition of the Caenorhabditis elegans intestinal terminal web is maintained by LET-413.

We wish to understand how organ-specific structures assemble during embryonic development. In the present paper, we consider what determines the subapical position of the terminal web in the intestinal cells of the nematode Caenorhabditis elegans. The terminal web refers to the organelle-depleted, intermediate filament-rich layer of cytoplasm that underlies the apical microvilli of polarized epithelial cells. It is generally regarded as the anchor for actin rootlets protruding from the microvillar cores. We demonstrate that: (i) the widely used monoclonal antibody MH33 reacts (only) with the gut-specific intermediate filament protein encoded by the ifb-2 gene; (ii) IFB-2 protein accumulates near the gut lumen beginning at the lima bean stage of embryogenesis and remains associated with the gut lumen into adulthood; and (iii) as revealed by immunoelectron microscopy, IFB-2 protein is confined to a discrete circumferential subapical layer within the intestinal terminal web (known in nematodes as the "endotube"); this layer joins directly to the apical junction complexes that connect adjacent gut cells. To investigate what determines the disposition of the IFB-2-containing structure as the terminal web assembles during development, RNAi was used to remove the functions of gene products previously shown to be involved in the overall apicobasal polarity of the developing gut cell. Removal of dlg-1, ajm-1, or hmp-1 function has little effect on the overall position or continuity of the terminal web IFB-2-containing layer. In contrast, removal of the function of the let-413 gene leads to a basolateral expansion of the terminal web, to the point where it can now extend around the entire circumference of the gut cell. The same treatment also leads to concordant basolateral expansion of both gut cell cortical actin and the actin-associated protein ERM-1. LET-413 has previously been shown to be basolaterally located and to prevent the basolateral expansion of several individual apical proteins. In the present context, we conclude that LET-413 is also necessary to maintain the entire terminal web or brush border assembly at the apical surface of C. elegans gut cells, a dramatic example of the so-called "fence" function ascribed to epithelial cell junctions. On the other hand, LET-413 is not necessary to establish this apical location during early development. Finally, the distance at which the terminal web intermediate filament layer lies beneath the gut cell surface (both apical and basolateral) must be determined independently of apical junction position.

Animals↗

PubMed2004

A new class of ubiquitin extension proteins secreted by the dorsal pharyngeal gland in plant parasitic cyst nematodes.

By performing cDNA AFLP on pre- and early parasitic juveniles, we identified genes encoding a novel type of ubiquitin extension proteins secreted by the dorsal pharyngeal gland in the cyst nematode Heterodera schachtii. The proteins consist of three domains, a signal peptide for secretion, a mono-ubiquitin domain, and a short C-terminal positively charged domain. A gfp-fusion of this protein is targeted to the nucleolus in tobacco BY-2 cells. We hypothesize that the C-terminal peptide might have a regulatory function during syncytium formation in plant roots.

Amino Acid Sequence↗

PubMed2003

A high-throughput screening system for genes extending life-span.

We developed a high-throughput functional genomic screening system that allows identification of genes prolonging life-span in the baker's yeast Saccharomyces cerevisiae. The method is based on isolating yeast mother cells with extended number of cell divisions as indicated by the increased number of bud scars on their surface. Fluorescently labelled Wheat Germ Agglutinin was used for specific staining of chitin, a major component of bud scars. Screening of a human HepG2 cDNA expression library in yeast resulted in the isolation of 12 yeast transformants with a potentially prolonged life-span. The transgene in one of the lines was identified as ferritin light chain (FTL) and studied in more detail. Yeast cells containing FTL showed an enhanced iron and H(2)O(2) resistance, a reduced cell death rate and an increased number of cell divisions. Overexpression of FTL in the nematode Caenorhabditis elegans resulted in a life-span increase of 8% confirming our yeast observations in a multicellular organism. Our data demonstrate that this method permits a fast screening of libraries for hunting genes involved in ageing processes.

Ferritins↗