In: Mathematical Biosciences, 2004, vol. 191, p. 207
A model is presented of competition between sensory axons for trophic molecules (e.g. a neurotrophin such as NGF), produced in a region of skin small enough to permit their free diffusion throughout it; e.g., a touch dome, or a vibrissal follicle hair sinus. The variables specified are the number of high affinity trophic factor receptors per axon terminal and the concentration of trophic factor...
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In: Journal of Multivariate Analysis, 2005, vol. 93, p. 180-197
This paper proposes a unified treatment of maximum likelihood estimates of angular Gaussian and multivariate Cauchy distributions in both the real and the complex case. The complex case is relevant in shape analysis. We describe in full generality the set of maxima of the corresponding log-likelihood functions with respect to an arbitrary probability measure. Our tools are the convexity of...
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In: Journal of Computational Physics, 2005, vol. 204, p. 292-301
Due to their rapid – often exponential – convergence as the number N of interpolation/collocation points is increased, polynomial pseudospectral methods are very efficient in solving smooth boundary value problems. However, when the solution displays boundary layers and/or interior fronts, this fast convergence will merely occur with very large N. To address this difficulty, we present a...
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In: Ecology, 2004, vol. 85, p. 823-833
While host stress in vertebrate populations has often been linked to outbreaks of epidemics, which are attributed to the immuno-compromise of the stressed hosts, no predictions have been made about the response of invertebrate host populations to stressful conditions. Experiments conducted on individual invertebrate hosts, however, suggest that starved hosts may be a poor resource for...
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In: Animal Behaviour, 2004, vol. 68, p. 589-598
Although the fitness benefits of learning are well understood, we know little about its costs; yet both are essential to understand the evolution of animal learning. We tested the hypothesis that learning has an operating cost, such that an animal repeatedly forced to use its learning ability would show a reduction in some fitness component(s), relative to an animal of the same genotype that does...
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In: Journal of Evolutionary Biology, 2004, vol. 17, p. 1402-1404
Salathé and Ebert (2003, J. Evol. Biol. 16: 976-985) have shown that the mean logarithmic fitness of Daphnia magna clones declined faster than linearly with increasing inbreeding coefficient F. They interpreted this result as evidence for synergistic epistasis. Trouve et al. (2004, J. Evol. Biol., doi: 10.1111/j.1420-9101.2004.00755.x) suggested that hybrid vigour could be an alternative...
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In: Journal of Experimental Biology, 2004, vol. 207, p. 179-188
An understanding of associative learning is facilitated if it can be analyzed in a simple animal like the fruit fly Drosophila. Here, we introduce the first visual associative learning paradigm for larval Drosophila; this is remarkable as larvae have an order of magnitude fewer neurons than adult flies. Larvae were subjected to either of two reciprocal training regimes: Light+/Dark- or...
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In: Journal of Biological Chemistry, 2004, vol. 279, p. 1161-1166
Glutaminyl-tRNA synthetase is thought to be absent from organelles. Instead, Gln-tRNA is formed via the transamidation pathway, the other route to this essential compound in protein biosynthesis. However, it was previously shown that glutaminyl-tRNA synthetase activity is present in Leishmania mitochondria. This work identifies genes encoding glutaminyl- and glutamyl-tRNA synthetase in the...
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In: Journal of Biological Chemistry, 2004, vol. 279, p. 42363-42368
Apicomplexan parasites have the smallest known mitochondrial genome. It consists of a repeated element of ~6–7 kb in length and encodes three mitochondrial proteins, a number of rRNA fragments, but no tRNAs. It has therefore been postulated that in apicomplexans all tRNAs required for mitochondrial translation are imported from the cytosol. To provide direct evidence for this process we have...
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In: EMBO reports, 2004, vol. 5, p. 268-273
The protozoan Trypanosoma brucei has a single mitochondrion and lacks an apoptotic machinery. Here we show that expression of the proapoptotic protein Bax in T. brucei causes the release of cytochrome c, the depolarization of the mitochondrial membrane potential and mitochondrial fission. However, in contrast to mammalian cells, the three events are temporally well separated. The release of...
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