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Université de Fribourg

Experimental evolution of field populations of Daphnia magna in response to parasite treatment

Zbinden, Marc ; Haag, Christoph R. ; Ebert, Dieter

In: Journal of Evolutionary Biology, 2008///doi:10.1111/j.1420-9101.2008.01541.x

Although there is little doubt that hosts evolve to reduce parasite damage, little is known about the evolutionary time scale on which host populations may adapt under natural conditions. Here we study the effects of selection by the microsporidian parasite Octosporea bayeri on populations of Daphnia magna. In a field study, we infected replicated populations of D. magna with the parasite,...

Université de Fribourg

Characterization and biological function of the ISOCHORISMATE SYNTHASE 2 gene of Arabidopsis thaliana

Garcion, Christophe ; Lohmann, Antje ; Lamodiere, Elisabeth ; Catinot, Jeremy ; Buchala, Antony J. ; Doermann, Peter ; Métraux, Jean-Pierre

In: Plant Physiology, 2009, p. -

Salicylic acid (SA) is an important mediator of plant defense response. In Arabidopsis thaliana, this compound was proposed to derive mainly from isochorismate, itself produced from chorismate through the activity of ICS1 (Isochorismate Synthase1). Null ics1 mutants still accumulate some SA, suggesting the existence of an enzymatic activity redundant with ICS1 or of an alternative...

Université de Fribourg

6S1/2-6P1/2 transition of Cs atoms in cubic and hexagonal solid ⁴He

Hofer, Adrian ; Moroshkin, Peter ; Ulzega, Simone ; Nettels, Daniel ; Müller-Siebert, Reinhard ; Weis, Antoine

In: Physical Review A, 2007, vol. 76, no. 2, p. 022502

We present a systematic experimental study of the absorption and fluorescence spectra of the 6S1/2-6P1/2 transition in Cs atoms isolated in solid ⁴He matrices. The bubble model developed earlier for alkali-metal atoms in liquid He is revised and applied to the present system. The analysis of the dependencies of absorption and fluorescence wavelengths on He...

Université de Fribourg

Pentatricopeptide repeat proteins in Trypanosoma brucei function in mitochondrial ribosomes

Pusnik, Mascha ; Small, Ian ; Read, Laurie K. ; Fabbro, Thomas ; Schneider, André

In: Molecular and Cellular Biology, 2007, vol. 27, no. 19, p. 6876-6888

The pentatricopeptide repeat (PPR), a degenerate 35-amino-acid motif, defines a novel eukaryotic protein family. Plants have 400 to 500 distinct PPR proteins, whereas other eukaryotes generally have fewer than 5. The few PPR proteins that have been studied have roles in organellar gene expression, probably via direct interaction with RNA. Here we show that the parasitic protozoan Trypanosoma...

Université de Fribourg

Bax function in the absence of mitochondria in the primitive protozoan Giardia lamblia

Hehl, Adrian B. ; Regos, Attila ; Schraner, Elisabeth ; Schneider, André

In: PLoS ONE, 2007, vol. 2, no. 5, p. e488

Bax-induced permeabilization of the mitochondrial outer membrane and release of cytochrome c are key events in apoptosis. Although Bax can compromise mitochondria in primitive unicellular organisms that lack a classical apoptotic machinery, it is still unclear if Bax alone is sufficient for this, or whether additional mitochondrial components are required. The protozoan parasite Giardia lamblia...