Differential Equations for Algebraic Functions

It is classical that univariate algebraic functions satisfy linear differential equations with polynomial coefficients. Linear recurrences follow for the coefficients of their power series expansions. We show that the linear differential equation of minimal order has coefficients whose degree is cubic in the degree of the function. We also show that there exists a linear differential equation of order linear in the degree whose coefficients are only of quadratic degree. Furthermore, we prove the existence of recurrences of order and degree close to optimal. We study the complexity of computing these differential equations and recurrences. We deduce a fast algorithm for the expansion of algebraic series

Novel ligature methods for studying sublethal effects of sit-and-wait predators: test using Cordulegaster boltonii (Donovan, 1807) larvae (Anisoptera: Cordulegasteridae)

A novel method of labial palp ligature was tested as a substitute for palp ablation for studying sublethal effects of larvae of C. boltonii on prey populations and their consequences for ecosystem functioning. Two alternative types of ligature were designed to test for neutral or aggressive, but non-lethal, predator-prey interaction effects. Ligature efficiency in preventing prey capture was very high and the effects on larval survival and emergence success were negligible. Potential advantages and drawbacks, compared to other methods, are discussed. The results indicate that this fully reversible method should be applied whenever possible, especially for naturally rare or endangered odon. spp

Transcriptome profiling of the feeding-to-fasting transition in chicken liver

<p>Abstract</p> <p>Background</p> <p>Starvation triggers a complex array of adaptative metabolic responses including energy-metabolic responses, a process which must imply tissue specific alterations in gene expression and in which the liver plays a central role. The present study aimed to describe the evolution of global gene expression profiles in liver of 4-week-old male chickens during a 48 h fasting period using a chicken 20 K oligoarray.</p> <p>Results</p> <p>A large number of genes were modulated by fasting (3532 genes with a pvalue corrected by Benjamini-Hochberg < 0.01); 2062 showed an amplitude of variation higher than +/- 40% among those, 1162 presented an human ortholog, allowing to collect functional information. Notably more genes were down-regulated than up-regulated, whatever the duration of fasting (16 h or 48 h). The number of genes differentially expressed after 48 h of fasting was 3.5-fold higher than after 16 h of fasting. Four clusters of co-expressed genes were identified by a hierarchical cluster analysis. Gene Ontology, KEGG and Ingenuity databases were then used to identify the metabolic processes associated to each cluster. After 16 h of fasting, genes involved in ketogenesis, gluconeogenesis and mitochondrial or peroxisomal fatty acid beta-oxidation, were up-regulated (cluster-1) whereas genes involved in fatty acid and cholesterol synthesis were down-regulated (cluster-2). For all genes tested, the microarray data was confirmed by quantitative RT-PCR. Most genes were altered by fasting as already reported in mammals. A notable exception was the <it>HMG-CoA synthase 1 </it>gene, which was up-regulated following 16 and 48 h of fasting while the other genes involved in cholesterol metabolism were down-regulated as reported in mammalian studies. We further focused on genes not represented on the microarray and candidates for the regulation of the target genes belonging to cluster-1 and -2 and involved in lipid metabolism. Data are provided concerning PPARa, SREBP1, SREBP2, NR1H3 transcription factors and two desaturases (FADS1, FADS2).</p> <p>Conclusion</p> <p>This study evidences numerous genes altered by starvation in chickens and suggests a global repression of cellular activity in response to this stressor. The central role of lipid and acetyl-CoA metabolisms and its regulation at transcriptional level are confirmed in chicken liver in response to short-term fasting. Interesting expression modulations were observed for <it>NR1H3, FADS1 </it>and <it>FADS2 </it>genes. Further studies are needed to precise their role in the complex regulatory network controlling lipid metabolism.</p

Segregation of a major gene influencing ovulation in progeny of Lacaune meat sheep

Inheritance of the ovulation rate (OR) in the Lacaune meat breed was studied through records from a small nucleus of 36 hyper-prolific ewes screened on farms on the basis of their natural litter size, and from progeny data of three selected Lacaune sires. These sires were chosen at the AI centre according to their breeding values estimated for the mean and the variability of their daughters' litter size. Non-carrier Lacaune dairy ewes were inseminated to produce 121 F1 daughters and 27 F1 sons. Twelve sons (four from each sire) were used in turn to inseminate non-carrier Lacaune dairy ewes providing 260 BC progeny ewes. F1 and BC progeny were brought from private farms and gathered after weaning on an experimental farm where ovulation rates were recorded in the first and second breeding seasons. With an average of 6.5 records each, the mean OR of hyper-prolific ewes was very high (5.34), and 38.4% of records showed a rate of 6 or more. F1 data showed high repeatability of OR (r = 0.54) within ewe, with significant variability among ewes. High OR (≥ 4) were observed in each family. A segregation analysis provided a significant likelihood ratio and classified the three founders as heterozygous. BC ewes also displayed high repeatability of OR (r = 0.47) and the mean OR varied considerably between families (from 1.24 to 1.78). Seven of the 12 BC families presented high-ovulating ewes (at least one record ≥ 4) and segregation analysis yielded a highly significant likelihood ratio as compared to an empirical test distribution. The high variability of the mean ovulation rate shown by a small group of daughters of BC ewes inseminated by putative carrier F1 rams, and the very high ovulation rate observed for some of these ewe lambs, confirmed the segregation of a major gene with two co-dominant alleles borne by an autosome. The difference between homozygous non-carriers and heterozygous ewes was about one ovulation on the observed scale and 2.2 standard deviations on the underlying scale

Spatial spring distribution of the copepod Eurytemora affinis (Copepoda,Calanoida) in a restoring estuary, the Scheldt (Belgium)

The spatial spring distribution of Eurytemora affinis (adults and C5) in the Scheldt estuary (Belgium) brackish and freshwater reacheswas studied in between 1996 and 2007. The bulk of the E. affinis population being generally situated in the brackish water reach (salinity > 0.5); we studied which environmental factors are responsible for its recent sporadic occurrence in the freshwater estuarine reach. Using PLS analysis, it is shown that its presence upstream is limited by a sufficient oxygen concentration (>4mg l-1) that is associated with temperature. Not only are the environmental conditions in the upstream zone important, but also the frequent presence of an O2 minimum zone in the mid-estuary (O2 min < 1.3mg l-1) seems to block the movement of the downstream E. affinis population in an upstream direction. Occasionally, the bulk of the population is however situated upstream. During these periods, high E. affinis abundancewas also observed in the Durme tributary. Our findings suggest the possibility to use E. affinis as an “indicator” species ofwaterquality, but also lead us to stress the necessity to consider conditions over the entire estuary when studying restoration effects, not exclusively in the zone of interest

Pyroséquençage pour le développement d'EST et de SNP aviaires

Le but du programme est de combler les déficits en marqueurs observés pour trois espèces aviaires : la caille, le canard et la poule. La stratégie choisie est l'obtention, à partir de plusieurs individus de lignées d'intérêt, de SNP (Single Nucleotide Polymorphism, polymorphisme d'un nucléotide) par une nouvelle technologie de séquençage à haut débit (séquenceur 454 GS-FLX, Roche). Nous séquençons des représentations réduites du génome, en sélectionnant d'une part des fragments de restriction d'ADN génomique - les mêmes chez tous les individus - et d'autre part les transcrits qui représentent globalement la partie du génome correspondant aux gènes exprimés. Ces expérimentations sont réalisées à partir d'échantillons d'ADN ou d'ARN issus d'individus de lignées à l'origine de croisements existants, pour chacune des trois espèces. Les données générées par plusieurs "runs" de séquence seront traitées in silico : contigage à haut débit, recherche de SNP, comparaison avec les banques de séquences connues...En plus de l'intérêt que représente la production d'un très grand nombre de SNP nouveaux, cette technologie devrait permettre de mieux séquencer les régions riches en (G+C) correspondant aux plus petits des microchromosomes pour lesquels il n'y a pas de séquence chez la poule. La comparaison des séquences des transcrits obtenues chez la caille et le canard avec la séquence du génome de la poule permettra d'établir une "cartographie virtuelle" des SNP obtenus, grâce à la grande conservation de synténie existant entre ces trois espèces

Déterminisme génétique de la prolificité chez les ovins (clonage positionnel du gène Booroola et localisation du gène Lacaune)

MONTPELLIER-SupAgro La Gaillarde (341722306) / SudocSudocFranceF

MarkerSet: a marker selection tool based on markers location and informativity in experimental designs

International audienceBackground: The recent sequencing of full genomes has led to the availability of many SNP markers which are very useful for the mapping of complex traits. In livestock production, there are still no commercial arrays and many studies use home-made sets of SNPs. Thus, the current methodologies for SNP genotyping are still expensive and it is a crucial step to select the SNPs to use. Indeed, the main factors affecting the power of the linkage analyses are the density of the genetic map and the heterozygosity of markers in tested animal parents. Findings: This is why we have developed a PERL program selecting a defined number of markers based on their locations on the genome and their informativity in specific experimental designs. As an option, different experimental designs can be combined in order to select the best possible common marker set. The program has been tested using different conditions of marker informativity and density with both real and simulated datasets. The results show the efficiency of our program to select the most informative markers even if there is a wide range of informativity for whole genome scan mapping analyses. In case of combination of different experimental crosses, the multidesign mode can optimize the SNP markers selection. Conclusion: Written in PERL, it assures a maximum portability to other operating systems (OS) and the source code availability for user modifications. Except for the simulation mode which could be time consuming, MarkerSet can compute results in a very short time

MarkerSet: a marker selection tool based on markers location and informativity in experimental designs

Abstract Background The recent sequencing of full genomes has led to the availability of many SNP markers which are very useful for the mapping of complex traits. In livestock production, there are still no commercial arrays and many studies use home-made sets of SNPs. Thus, the current methodologies for SNP genotyping are still expensive and it is a crucial step to select the SNPs to use. Indeed, the main factors affecting the power of the linkage analyses are the density of the genetic map and the heterozygosity of markers in tested animal parents. Findings This is why we have developed a PERL program selecting a defined number of markers based on their locations on the genome and their informativity in specific experimental designs. As an option, different experimental designs can be combined in order to select the best possible common marker set. The program has been tested using different conditions of marker informativity and density with both real and simulated datasets. The results show the efficiency of our program to select the most informative markers even if there is a wide range of informativity for whole genome scan mapping analyses. In case of combination of different experimental crosses, the multidesign mode can optimize the SNP markers selection. Conclusion Written in PERL, it assures a maximum portability to other operating systems (OS) and the source code availability for user modifications. Except for the simulation mode which could be time consuming, MarkerSet can compute results in a very short time.</p