Biomedical subjects

T Schiex

Publications and source records attributed to T Schiex.

3 recordsLinked to original sources

PubMed2002

Genome sequence of the plant pathogen Ralstonia solanacearum.

Ralstonia solanacearum is a devastating, soil-borne plant pathogen with a global distribution and an unusually wide host range. It is a model system for the dissection of molecular determinants governing pathogenicity. We present here the complete genome sequence and its analysis of strain GMI1000. The 5.8-megabase (Mb) genome is organized into two replicons: a 3.7-Mb chromosome and a 2.1-Mb megaplasmid. Both replicons have a mosaic structure providing evidence for the acquisition of genes through horizontal gene transfer. Regions containing genetically mobile elements associated with the percentage of G+C bias may have an important function in genome evolution. The genome encodes many proteins potentially associated with a role in pathogenicity. In particular, many putative attachment factors were identified. The complete repertoire of type III secreted effector proteins can be studied. Over 40 candidates were identified. Comparison with other genomes suggests that bacterial plant pathogens and animal pathogens harbour distinct arrays of specialized type III-dependent effectors.

Bacterial Proteins↗

PubMed1998

A composite genetic map of the parasitoid wasp Trichogramma brassicae based on RAPD markers.

Three linkage maps of the genome of the microhymenopteran Trichogramma brassicae were constructed from the analysis of segregation of random amplified polymorphic DNA markers in three F2 populations. These populations were composed of the haploid male progeny of several virgin F1 females, which resulted from the breeding of four parental lines that were nearly fixed for different random amplified polymorphic DNA markers and that were polymorphic for longevity and fecundity characters. As the order of markers common to the three mapping populations was found to be well conserved, a composite linkage map was constructed. Eighty-four markers were organized into five linkage groups and two pairs. The mean interval between two markers was 17.7 cM, and the map spanned 1330 cM.

Animals↗

PubMed1997

CARTHAGENE: constructing and joining maximum likelihood genetic maps.

Genetic mapping is an important step in the study of any organism. An accurate genetic map is extremely valuable for locating genes or more generally either qualitative or quantitative trait loci (QTL). This paper presents a new approach to two important problems in genetic mapping: automatically ordering markers to obtain a multipoint maximum likelihood map and building a multipoint maximum likelihood map using pooled data from several crosses. The approach is embodied in an hybrid algorithm that mixes the statistical optimization algorithm EM with local search techniques which have been developed in the artificial intelligence and operations research communities. An efficient implementation of the EM algorithm provides maximum likelihood recombination fractions, while the local search techniques look for orders that maximize this maximum likelihood. The specificity of the approach lies in the neighborhood structure used in the local search algorithms which has been inspired by an analogy between the marker ordering problem and the famous traveling salesman problem. The approach has been used to build joined maps for the wasp Trichogramma brassicae and on random pooled data sets. In both cases, it compares quite favorably with existing softwares as far as maximum likelihood is considered as a significant criteria.

Algorithms↗