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Université de Fribourg

Multiple genetic pathways involving the Caenorhabditis elegans Bloom's syndrome genes him-6, rad-51, and top-3 are needed to maintain genome stability in the germ line

Wicky, Chantal ; Alpi, Arno ; Passannante, Myriam ; Rose, Ann ; Gartner, Anton ; Müller, Fritz

In: Molecular and Cellular Biology, 2004, vol. 24, p. 5016-5027

Bloom's syndrome (BS) is an autosomal-recessive human disorder caused by mutations in the BS RecQ helicase and is associated with loss of genomic integrity and an increased incidence of cancer. We analyzed the mitotic and the meiotic roles of Caenorhabditis elegans him-6, which we show to encode the ortholog of the human BS gene. Mutations in him-6 result in an enhanced irradiation sensitivity, a...

Université de Fribourg

Covariation of mitochondrial genome size with gene lengths: evidence for gene length reduction during mitochondrial evolution

Schneider, André ; Ebert, Dieter

In: Journal of Molecular Evolution, 2004, vol. 59, p. 90-96

Reduction of genome size and gene shortening have been observed in a number of parasitic and mutualistic intracellular symbionts. Reduction of coding capacity is also a unifying principle in the evolutionary history of mitochondria, but little is known about the evolution of gene length in mitochondria. The genes for cytochrome c oxidase subunits I–III, cytochrome b, and the large and small...

Université de Fribourg

The Caenorhabditis elegans ortholog of C21orf80, a potential new protein O-fucosyltransferase, is required for normal development

Menzel, Olivier ; Vellai, Tibor ; Takacs-Vellai, Krisztina ; Reymond, Alexandre ; Müller, Fritz ; Antonarakis, Stylianos E. ; Guipponi, Michel

In: Genomics, 2004, vol. 84, p. 320-330

Down syndrome (DS), as a phenotypic result of trisomy 21, is the most frequent aneuploidy at birth and the most common known genetic cause of mental retardation. DS is also characterized by other phenotypes affecting many organs, including brain, muscle, heart, limbs, gastrointestinal tract, skeleton, and blood. Any of the human chromosome 21 (Hsa21) genes may contribute to some of the DS...

Université de Fribourg

Chromatin diminution leads to rapid evolutionary changes in the organization of the germ line genomes of the parasitic nematodes A. suum and P. univalens

Bachmann-Waldmann, Christa ; Jentsch, Stephan ; Tobler, Heinz ; Müller, Fritz

In: Molecular and Biochemical Parasitology, 2004, vol. 134, p. 53-64

Chromatin diminution in the parasitic nematodes Ascaris suum and Parascaris univalens represents a rather complex molecular phenomenon that includes chromosomal breakage, DNA degradation and new telomere formation. At a given elimination site, DNA breakage and new telomere addition does not take place at a single chromosomal locus but at many different places within a several kilobase long...

Université de Fribourg

Integration of complex larval chemosensory organs into the adult nervous system of Drosophila

Gendre, Nanaë ; Lüer, Karin ; Friche, Sandrine ; Grillenzoni, Nicola ; Ramaekers, Ariane ; Technau, Gerhard M. ; Stocker, Reinhard F.

In: Development, 2004, vol. 131, p. 83-92

The sense organs of adult Drosophila, and holometabolous insects in general, derive essentially from imaginal discs and hence are adult specific. Experimental evidence presented here, however, suggests a different developmental design for the three largely gustatory sense organs located along the pharynx. In a comprehensive cellular analysis, we show that the posteriormost of the three organs...

Université de Fribourg

The T-stem determines the cytosolic or mitochondrial localization of trypanosomal tRNAsMet

Crausaz Esseiva, Anne ; Maréchal-Drouard, Laurence ; Cosset, Anne ; Schneider, André

In: Molecular Biology of the Cell, 2004, vol. 15, p. 2750-2757

The mitochondrion of Trypanosoma brucei lacks tRNA genes. Organellar translation therefore depends on import of cytosolic, nucleus-encoded tRNAs. Except for the cytosol-specific initiator tRNAMet, all trypanosomal tRNAs function in both the cytosol and the mitochondrion. The initiator tRNAMet is closely related to the imported elongator tRNAMet. Thus, the distinct localization of the two tRNAsMet...

Université de Fribourg

Expression of a major surface protein of Trypanosoma brucei insect forms is controlled by the activity of mitochondrial enzymes

Vassella, Erik ; Probst, Matthias ; Schneider, André ; Studer, Erwin ; Kunz Renggli, Christina ; Roditi, Isabel

In: Molecular Biology of the Cell, 2004, vol. 15, p. 3986-3993

In cycling between the mammalian host and the tsetse fly vector, trypanosomes undergo major changes in energy metabolism and surface coat composition. Early procyclic (insect) forms in the tsetse fly midgut are coated by glycoproteins known as EP and GPEET procyclins. EP expression continues in late procyclic forms, whereas GPEET is down-regulated. In culture, expression of GPEET is modulated by...

Université de Fribourg

Dissecting the ß-aminobutyric acid–induced priming phenomenon in Arabidopsis

Ton, Jurriaan ; Jakab, Gabor ; Toquin, Valérie ; Flors, Victor ; Iavicoli, Annalisa ; Maeder, Muriel N. ; Métraux, Jean-Pierre ; Mauch-Mani, Brigitte

In: The Plant Cell, 2005, vol. 17, p. 987-999

Plants treated with the nonprotein amino acid ß-aminobutyric acid (BABA) develop an enhanced capacity to resist biotic and abiotic stresses. This BABA-induced resistance (BABA-IR) is associated with an augmented capacity to express basal defense responses, a phenomenon known as priming. Based on the observation that high amounts of BABA induce sterility in Arabidopsis thaliana, a mutagenesis...

Université de Fribourg

Developmental origin of wiring specificity in the olfactory system of Drosophila

Jefferis, Gregory S. X. E. ; Vyas, Raj M. ; Berdnik, Daniela ; Ramaekers, Ariane ; Stocker, Reinhard F. ; Tanaka, Nobuaki K. ; Ito, Kei ; Luo, Liqun

In: Development, 2004, vol. 131, p. 117-130

In both insects and mammals, olfactory receptor neurons (ORNs) expressing specific olfactory receptors converge their axons onto specific glomeruli, creating a spatial map in the brain. We have previously shown that second order projection neurons (PNs) in Drosophila are prespecified by lineage and birth order to send their dendrites to one of ~50 glomeruli in the antennal lobe. How can a given...

Université de Fribourg

Paradoxes in the logistic equation?

Gabriel, Jean-Pierre ; Saucy, Francis ; Bersier, Louis-Félix

In: Ecological Modelling

Levins and Ginzburg raised two paradoxes concerning the logistic equation of population growth. None of them received a satisfactory answer within the frame of the original equation. Here, we propose solutions to both paradoxes.