TraceAncestor: a Tool to Infer Unphased Phylogenomic Karyotypes of Admixed Plant Genomes

International audienc

GeMo: a web-based platform for the visualization and curation of genome ancestry mosaics

International audienceIn silico chromosome painting is a technique by which contributions of distinct genetic groups are represented along chromosomes of hybrid individuals. This type of analysis is used to study the mechanisms by which these individuals were formed. Such techniques are well adapted to identify genetic groups contributing to these individuals as well as hybridization events. It can also be used to follow chromosomal recombinations that occurred naturally or were generated by selective breeding. Here, we present GeMo, a novel interactive web-based and user-oriented interface to visualize in a linear-based fashion results of in silico chromosome painting. To facilitate data input generation, a script to execute analytical commands is provided and an interactive data curation mode is supported to ensure consistency of the automated procedure. GeMo contains preloaded datasets from published studies on crop domestication but can be applied to other purposes, such as breeding programs Although only applied so far on plants, GeMo can handle data from animals as well. Database URL: https://gemo.southgreen.fr

Analysis of Fretting Behavior of Silver and Gold Flashed Palladium-nickel Dissimilar Coatings for Connectors

International audienceIt is well known that good wear performance can be obtained with Au-flashed palladium-nickel sphere on flat contacts simulating various connector applications. It has also been shown that these good wear properties could be recorded for asymmetrical coatings such as a noble metal sphere on Au-flashed palladium-nickel. In this paper we investigate the fretting properties of such asymmetrical coatings particularly of Ag versus Au flashed PdNi. The contacts are submitted to severe fretting wear by applying imposed sine displacements of amplitude similar to the Hertz contact radius. The contact resistance, the friction force and wear evolutions were analyzed and correlated to 3D profilometry measurements allowing wear volumes quantification and EDS elemental identification of the wear tracks.Very different behaviors are observed whether the silver coating is on the sphere or on the plane though in both case the embedding of the oxidized wear debris by silver improves the fretting behavior. The transfer of silver from the sphere contact onto the palladium nickel flat is seen to be beneficial to the electrical stability of the interface for a long time, leading to more stable results than even silver/silver contacts. Nevertheless an unusual phenomenon of the galling type is observed for which more investigations are needed

CulebrONT : a streamlined long reads multi-assembler pipeline for prokaryotic and eukaryotic genomes

Using long reads provides higher contiguity and better genome assemblies. However, producing such high quality sequences from raw reads requires to chain a growing set of tools, and determining the best workflow is a complex task. To tackle this challenge, we developed CulebrONT, an open-source, scalable, modular and traceable Snakemake pipeline for assembling long reads data. CulebrONT enables to perform tests on multiple samples and multiple long reads assemblers in parallel, and can optionally perform, downstream circularization and polishing. It further provides a range of assembly quality metrics summarized in a final user-friendly report. CulebrONT alleviates the difficulties of assembly pipelines development, and allow users to identify the best assembly options

Durability of some asymmetrical contact pairs for connector application

International audienceReliability of connectors is still a major concern for end users in many applications. One way to improve it is to optimize the surface coatings deposited on base substrates. Although gold remains the most widely used contact plating material, many alternative coatings have been developed in the past or recent years. Among these alternatives are silver final coatings and gold flash over palladium-nickel plated alloy. The properties of these two platings have been mainly investigated in symmetrical configurations where male and female contacts have similar deposits. In this work, asymmetrical configurations - where platings on male and female contacts are dissimilar - are studied. Wear behaviour was investigated with friction and fretting tests. The aim was to characterize the role of the various layers on the wear performances of contacts. Contact resistance behaviours were measured and correlated to the wear tracks investigated with various techniques such as SEM, EDS and 3D-Profilometry. It is shown that in some cases dissimilar final coatings on male and female contacts can significantly improve durability

Genotyping by sequencing can reveal the complex mosaic genomes in gene pools resulting from reticulate evolution: a case study in diploid and polyploid citrus

International audienceBackground and Aims Reticulate evolution, coupled with reproductive features limiting further interspecific recombinations, results in admixed mosaics of large genomic fragments from the ancestral taxa. Whole-genome sequencing (WGS) data are powerful tools to decipher such complex genomes but still too costly to be used for large populations. The aim of this work was to develop an approach to infer phylogenomic structures in diploid, triploid and tetraploid individuals from sequencing data in reduced genome complexity libraries. The approach was applied to the cultivated Citrus gene pool resulting from reticulate evolution involving four ancestral taxa, C. maxima, C. medico, C. micrantha and C. reticulara. Methods A genotyping, by sequencing library was established with the restriction enzyme ApeK.1 applying one base (A) selection. Diagnostic single nucleotide polymorphisms (DSNPs) for the four ancestral taxa were mined in 29 representative varieties. A generic pipeline based on a maximum likelihood analysis of the number of read data was established to infer ancestral contributions along the genome of diploid, triploid and tetraploid individuals. The pipeline was applied to 48 diploid, four triploid and one tetraploid citrus accessions. Key Results Among 43 598 mined SNPs, we identified a set of 15 946 DSNPs covering the whole genome with a distribution similar to that of gene sequences. The set efficiently inferred the phylogenomic karyotype of the 53 analysed accessions, providing patterns for common accessions very close to that previously established using WGS data. The complex phylogenomic karyotypes of 21 cultivated citrus, including bergamot, triploid and tetraploid limes, were revealed for the first time. Conclusions The pipeline, available online, efficiently inferred the phylogenomic structures of diploid, triploid and tetraploid citrus. it will be useful for any species whose reproductive behaviour resulted in an interspecific mosaic of large genomie fragments. It can also be used for the first generations of interspecific breeding schem

Compatibility of Gold, Palladium and hard Silver based plating systems for connector applications

International audiencePlating systems of electrical contacts are key technologies for connectors in terms of electrical and mechanical reliability performance. Au/Ni is historically the reference plating system and Au/PdNi/Ni is widely used since 1986. More recently, plating systems like Au/Ag/Ni, Au/NiW, AgPd/Ni and AgSb/Ni were also introduced. Nevertheless, published scientific literature, concerning tribological compatibility of these various plating systems, is limited. This research work is a simplified approach to study compatibility, in terms of durability & wear, between Au/Ni, AuPdNi/Ni, Au/Ag/Ni and AgSb/Ni under different contact pressures or normal forces. Durability and frictional wear testing were performed. Various surface analysis techniques were used to analyze wear tracks and investigate wear mechanisms as well as their impact on contact resistance. Results show that terminal contact pressure range is a key parameter to take into account when mating two different platings

Comparative performance study of different conventional silver and hard silver-plating processes for connector applications

International audienceSilver plating processes have become key technologies for connector applications in the past 10 years. The signif- icant utilization increase of various pure silver plating types and various silver alloys, for electrical contact surface finishing, can be attributed to several factors such as the development of electrical vehicles, the continuous rise of many connector operating temperatures up to 150°C and 180°C, where Tin plating cannot be used anymore, the increase of smaller-size power connectors requiring higher electrical conductivity than what can be provided by hard gold plating, and finally the severe increase of Gold and Palladium metal prices. Connector users sometimes have difficulties to understand the performance differences between all the existing silver-based plating offering. This work presents a summary between several widely used commercial silver-based deposits such as soft or hard pure silver, Antimony or Bismuth based silver alloys as well low friction silver coatings. Some key tribological, electrical and mechanical characteristics are compared. Some structural surface analysis is carried out to under- stand certain behaviour differences. The objective is to better define the optimal performance domain of each type of silver-plating technologies