RESUMO
From genetic point of view, differences between ancient and modern horses can be reconstructed by using the phylogeographic analysis of mitochondrial genomes and by studying phenotypically important nuclear loci. The variety of modern horse coat colors resulted from artificial selection indicates a high degree of domestication. We have conducted the phylogenetic analysis of mitochondrial DNA extracted from bone samples of six ancient horses from Tsaramburial in the Republic of Buryatia, and established that they belong to a haplogroup E by Achilli's classification. This haplogroup is found among modern horses of the Maremmano breed from Italy. Gray coat color different from wild type have been detected in two ancient horses, which demonstrates a sufficiently high domestication level of Buryat horses during the period I century BC to I century AD. The analysis of the mitochondrial genome hypervariable region fragments revealed that ancient Buryat horses belong to a haplotype X3 by Cieslak's classification, which is ancestral to the haplogroup X3 of modern horses in Mongolia, Tuva, and Buryatia.
Assuntos
Técnicas de Genotipagem , Haplótipos , Cavalos/genética , Animais , Domesticação , Genoma Mitocondrial , História Antiga , SibériaAssuntos
Cromossomos/genética , Proteínas de Ligação a DNA/genética , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Animais , Proteínas de Ligação a DNA/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/ultraestrutura , Mutação/genética , Glândulas Salivares/metabolismoRESUMO
The Suppressor of Underreplication ( SuUR) gene contributes to the regulation of DNA replication in regions of intercalary heterochromatin in salivary gland polytene chromosomes. In the SuUR mutant these regions complete replication earlier than in wild type and, as a consequence, undergo full polytenization. Here we describe the effects of ectopic expression of SuUR using the GAL4-UAS system. We demonstrate that ectopically expressed SuUR exerts qualitatively distinct influences on polyploid and diploid tissues. Ectopic expression of SuUR inhibits DNA replication in polytene salivary gland nuclei, and reduces the degree of amplification of chorion protein genes that occurs in the follicle cell lineage. Effects caused by ectopic SuUR in diploid tissues vary considerably; there is no obvious effect on eye formation, but apoptosis is observed in the wing disc, and wing shape is distorted. The effect of ectopic SuUR expression is enhanced by mutations in the genes E2F and mus209 ( PCNA). Differential responses of polyploid and diploid cells to ectopic SuUR may reflect differences in the mechanisms underlying mitotic cell cycles and endocycles.
