RESUMO
Eucalyptus urophylla is an important species in the Brazilian forest sector due to its rapid growth rates and resistance to disease. The aim of this study was to verify Mendelian inheritance, genetic linkage, and genotypic disequilibrium for 15 microsatellite loci, with the goal of producing a robust set of genetic markers. Mendelian inheritance and genetic linkage analyses were carried out using genotypes from maternal trees, and their open-pollinated seeds and genotypic disequilibrium were assessed using adult trees. By comparing heterozygous maternal genotypes and their seeds, we found no significant deviations from the expected 1:1 Mendelian segregation and the expected 1:1:1:1 segregation hypothesis for pairwise loci. For adult trees, we did not find strong evidence of genotypic imbalance for pairwise loci. Our results indicated that the analyzed set of microsatellite loci could be used to carry out analyses of genetic diversity, mating system, and parentage in E. urophylla.
Assuntos
Eucalyptus/genética , Desequilíbrio de Ligação , Repetições de Microssatélites , Frequência do Gene , Genótipo , Polimorfismo GenéticoRESUMO
Leptospira species colonize a significant proportion of rodent populations worldwide and produce life-threatening infections in accidental hosts, including humans. Complete genome sequencing of Leptospira interrogans serovar Copenhageni and comparative analysis with the available Leptospira interrogans serovar Lai genome reveal that despite overall genetic similarity there are significant structural differences, including a large chromosomal inversion and extensive variation in the number and distribution of insertion sequence elements. Genome sequence analysis elucidates many of the novel aspects of leptospiral physiology relating to energy metabolism, oxygen tolerance, two-component signal transduction systems, and mechanisms of pathogenesis. A broad array of transcriptional regulation proteins and two new families of afimbrial adhesins which contribute to host tissue colonization in the early steps of infection were identified. Differences in genes involved in the biosynthesis of lipopolysaccharide O side chains between the Copenhageni and Lai serovars were identified, offering an important starting point for the elucidation of the organism's complex polysaccharide surface antigens. Differences in adhesins and in lipopolysaccharide might be associated with the adaptation of serovars Copenhageni and Lai to different animal hosts. Hundreds of genes encoding surface-exposed lipoproteins and transmembrane outer membrane proteins were identified as candidates for development of vaccines for the prevention of leptospirosis.
Assuntos
Genoma Bacteriano , Genômica , Leptospira interrogans/fisiologia , Leptospira interrogans/patogenicidade , Animais , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Cricetinae , Humanos , Leptospira interrogans/classificação , Leptospira interrogans/genética , Leptospirose/microbiologia , Camundongos , Dados de Sequência Molecular , Análise de Sequência de DNA , Sorotipagem , Virulência/genéticaRESUMO
Xylella fastidiosa is a xylem-dwelling, insect-transmitted, gamma-proteobacterium that causes diseases in many plants, including grapevine, citrus, periwinkle, almond, oleander, and coffee. X. fastidiosa has an unusually broad host range, has an extensive geographical distribution throughout the American continent, and induces diverse disease phenotypes. Previous molecular analyses indicated three distinct groups of X. fastidiosa isolates that were expected to be genetically divergent. Here we report the genome sequence of X. fastidiosa (Temecula strain), isolated from a naturally infected grapevine with Pierce's disease (PD) in a wine-grape-growing region of California. Comparative analyses with a previously sequenced X. fastidiosa strain responsible for citrus variegated chlorosis (CVC) revealed that 98% of the PD X. fastidiosa Temecula genes are shared with the CVC X. fastidiosa strain 9a5c genes. Furthermore, the average amino acid identity of the open reading frames in the strains is 95.7%. Genomic differences are limited to phage-associated chromosomal rearrangements and deletions that also account for the strain-specific genes present in each genome. Genomic islands, one in each genome, were identified, and their presence in other X. fastidiosa strains was analyzed. We conclude that these two organisms have identical metabolic functions and are likely to use a common set of genes in plant colonization and pathogenesis, permitting convergence of functional genomic strategies.
Assuntos
Citrus/microbiologia , Gammaproteobacteria/genética , Genoma Bacteriano , Doenças das Plantas/microbiologia , Sequência de Bases , Dados de Sequência MolecularRESUMO
Com o propósito de determinar a relaçäo filogenética entre a cana-de-açúcar e membros da subtribo Saccharinae,a regiäo gênica nuclear ITS1-5,8S-ITS2 (ITS: espaçador interno transcrito; 5,8S: DNA ribossomal 5.8S), com alta taxa evolutiva, foi identificada no banco de dados do projeto genoma "Sugarcane Expressed Sequence Tag" (SUCEST). Uma análise através do método de parcimônia, utilizando esta regiäo e seqüências homólogas de 23 Andropogoneae retiradas da base de dados GenBank, indicou que a cana-de-açúcar é o grupo-irmäo de Saccharum sinense. No entanto, devido à pequena quantidade de caracteres informativos para parcimônia e à homoplasia presentes na regiäo ITS1-5,8S-ITS2, näo foi possível determinar com segurança a relaçäo filogenética entre a cana-de-açúcar e alguns dos demais membros da tribo Saccharine. Como alternativa para esta baixa resoluçäo, dezessete regiões gênicas nucleares, cloroplasmáticas ou mitocondriais foram selecionadas a partir do banco de dados SUCEST com o objetivo de encontrar marcadores mais apropriados para a reconstruçäo da filogenia da cana-de-açúcar. Entre elas, aquelas correspondentes à alfa-tubulina, rpl16, a rpoC2 apresentaram baixa incidência de polimorfismo e taxas de evoluçäo equivalentes ou mesmo maiores do que a observada para a regiäo ITS1-5,8S-ITS2. Estes marcadores säo propostos como preferenciais para estudos filogenéticos da subtribo Saccharinae.