Biology subjects

Ordonez, B.

Publications and source records attributed to Ordonez, B..

4 recordsLinked to original sources

bioRxiv2024

Comparative genomic analysis of a Colombian strain of Leptospira santarosai serogroup Autumnalis serovar Alice and inference of its virulence factors

IntroductionThe study aimed to characterize the genome of a Colombian strain of Leptospira santarosai to infer bacterial virulence factors. Materials and methodsUnder the approach of a quantitative research, an isolate of Colombian origin of L. santarosai was sequenced using new generation 454 GS FLX Titanium sequencers. Subsequently, bioinformatics programs were used for the physical description of the genome (number of genes, size), open reading frame prediction, prediction of proteins and their orthologs in other pathogenic species, of intermediate pathogenicity and non-pathogenic, cellular localization of proteins. ResultsThe assembly of the spirochete genome was achieved Leptospira santarosai serogroup Autumnalis serovar Aliceand the description of the genetic, structural and functional characteristics of its genes. It is concluded that the core- genome of the isolate is composed of 1747 proteins, which are common to all L. santarosai strains available in GenBank. It was determined that it has a total of 4,138 proteins, 141 of which are unique to its genome. The possible role of the virulence factors found in the Colombian isolate was identified and described. ConclusionsThe study contributes to the understanding of the pathophysiological mechanisms induced by Leptospira.

microbiology↗

bioRxiv2021

LD-CNV: rapid and simple discovery of chromosomal translocations using linkage disequilibrium between copy number variable loci

Large scale structural variations, such as chromosomal translocations, can have profound effects on fitness and phenotype, but are difficult to identify and characterize. Here, we describe a simple and effective method aimed at identifying translocations using only the dosage of sequence reads mapped on the reference genome. We binned reads on genomic segments sized according to sequencing coverage and identified instances when copy number segregated in populations. For each dosage-polymorphic 1Mb bin, we tested linkage disequilibrium with other variable bins. In nine potato (Solanum tuberosum) dihaploid families translocations affecting pericentromeric regions were common and in two cases were due to genomic misassembly. In two populations, we found evidence for translocation affecting euchromatic arms. In cv. PI 310467, a non-reciprocal translocation between chromosome 7 and 8 resulted in a 5-3 copy number change affecting several Mb at the respective chromosome tips. In cv. "Alca Tarma", the terminal arm of chromosome 4 translocated to the tip of chromosome 1. Using oligonucleotide-based fluorescent in situ hybridization painting probes (oligo-FISH), we tested and confirmed the predicted arrangement in PI 310467. In 192 natural accessions of Arabidopsis thaliana, dosage haplotypes tended to vary continuously and resulted in higher noise, but we identified pericentromeric LD suggesting the effect of repeats. This method should be useful in species where translocations are suspected because it tests linkage without the need for genotyping.

genomics↗

bioRxiv2020

Rare instances of haploid inducer DNA in potato dihaploids and ploidy-dependent genome instability

In cultivated tetraploid potato, reduction to diploidy (dihaploidy) allows hybridization to diploid germplasm, introgression breeding, and may facilitate the production of inbreds. Pollination with haploid inducers yields maternal dihaploids, as well as triploid and tetraploid hybrids. It is not known if dihaploids result from parthenogenesis, entailing development of embryos from unfertilized eggs, or genome elimination, entailing missegregation and loss of paternal chromosomes. A sign of genome elimination is the occasional persistence of haploid inducer DNA in some of the dihaploids. We characterized the genomes of 1,001 putative dihaploids and 134 hybrids produced by pollinating tetraploid clones with three haploid inducers, IVP35, IVP101, and PL4. We detected inheritance of full or partial chromosomes from the haploid inducer parent in 0.87% of the overall dihaploid progeny, irrespective of the combination of parental genotypes. Chromosomal breaks commonly affected the paternal genome in the dihaploid and tetraploid progeny, but not in the triploid progeny. Residual haploid inducer DNA is consistent with genome elimination as the mechanism of haploid induction. Further, the fact that paternal chromosome breaks are specific to dihaploids and tetraploid progeny suggests that they may be specific to 2x sperms, and supports the hypothesis that 2x sperms facilitate genome elimination.

plant biology↗

bioRxiv2019

Genomic Outcomes of Haploid Induction Crosses in Potato (Solanum tuberosum L.)

The challenges of breeding autotetraploid potato (Solanum tuberosum) have motivated the development of alternative breeding strategies. A common approach is to obtain uniparental dihaploids from a tetraploid of interest through pollination with S. tuberosum Andigenum Group (formerly S. phureja) cultivars. The mechanism underlying haploid formation of these crosses is unclear, and questions regarding the frequency of paternal DNA transmission remain. Previous reports described aneuploid and euploid progeny, which, in some cases, displayed genetic markers from the haploid inducer. Here, we surveyed a population of 167 presumed dihaploids for large-scale structural variation that would underlie chromosomal addition from the haploid inducer, and for small-scale introgression of genetic markers. In 19 progeny, we detected ten of the twelve possible trisomies and, in all cases, demonstrated the non-inducer parent origin of the additional chromosome. Deep sequencing indicated that occasional, short-tract signals appearing of haploid inducer origin were better explained as technical artifacts. Leveraging recurring CNV patterns, we documented sub-chromosomal dosage variation indicating segregation of polymorphic maternal haplotypes. Collectively, 52% of assayed chromosomal loci were classified as dosage variable. Our findings help elucidate the genomic consequences of potato haploid induction and suggest that most potato dihaploids will be free of residual pollinator DNA.

genomics↗