RESUMO
The genomic analysis of heterochromatin is essential for studying chromosome behavior as well as for understanding chromosome evolution. The Y chromosome of Drosophila melanogaster is entirely heterochromatic and the under-representation of this chromosome in genomic libraries together with the difficulty of assembling its sequence has made its study very difficult. Here, we present the construction of bacterial artificial chromosome (BAC) contigs from regions h14, h16 and the centromeric region h18. The analysis of these contigs shows that telomere-derived sequences are present at internal regions. In addition, immunostaining of prometaphase chromosomes with an antibody to the kinetochore-specific protein BubR1 has revealed the presence of this protein in some Y chromosome regions rich in telomere-related sequences. Collectively, our data provide further evidence for the hypothesis that the Drosophila Y chromosomes might have evolved from supernumerary chromosomes.
Assuntos
Drosophila melanogaster/genética , Heterocromatina/genética , Telômero/genética , Cromossomo Y/genética , Animais , Anticorpos/imunologia , Sequência de Bases , Proteínas de Ciclo Celular , Cromossomos Artificiais Bacterianos/genética , Cromossomos Artificiais de Levedura/genética , Mapeamento de Sequências Contíguas , Elementos de DNA Transponíveis , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Proteínas de Drosophila/fisiologia , Produtos do Gene gag/genética , Produtos do Gene gag/metabolismo , Produtos do Gene gag/fisiologia , Genômica , Hibridização in Situ Fluorescente , Masculino , Dados de Sequência Molecular , Proteínas Quinases/análise , Proteínas Quinases/imunologia , Proteínas Quinases/metabolismo , Proteínas Serina-Treonina Quinases , Cromossomo Y/química , Cromossomo Y/metabolismoRESUMO
The repetitive nature of heterochromatin hampers its analysis in general genome-sequencing projects. Specific studies are needed to extend the sequence into telomeric and centromeric heterochromatin. Drosophila telomeres lack the telomerase-generated repeats that are characteristic of other eukaryotic chromosomes. Instead, they consist of tandem arrays of HeT-A and TART elements. Herein, we present the genomic organization of the telomeres in the isogenic strain (y; cn bw sp) that was used for the Drosophila melanogaster sequencing project. The data indicate that the canonical features of telomere organization are widely conserved in evolution. In addition, we have identified full-length elements, likely competent elements, for HeT-A and TART.
Assuntos
Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Produtos do Gene gag/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Cromossomos Artificiais Bacterianos/genética , Evolução Molecular , Genes de Insetos , Genoma , Heterocromatina/genética , Modelos Genéticos , Dados de Sequência Molecular , Retroelementos/genética , Homologia de Sequência de Aminoácidos , Homologia de Sequência do Ácido Nucleico , Telômero/genéticaRESUMO
Drosophila telomeres do not have typical telomerase repeats. Instead, two families of non-LTR retrotransposons, HeT-A and TART, maintain telomere length by occasional transposition to the chromosome ends. Despite the work on Drosophila telomeres, its evolutionary origin remains controversial. Herein we describe a novel telomere-specific retroelement that we name TAHRE (Telomere-Associated and HeT-A-Related Element). The structure of the three telomere-specific elements indicates a common ancestor. These results suggest that preexisting transposable elements were recruited to perform the cellular function of telomere maintenance. A recruitment similar to that of a retrotransposal reverse transcriptase has been suggested as the common origin of telomerases.
Assuntos
Drosophila melanogaster/genética , Retroelementos/genética , Telômero/genética , Animais , Sequência de Bases , Cromossomos Artificiais Bacterianos/genética , Evolução Molecular , Modelos Genéticos , Dados de Sequência Molecular , FilogeniaRESUMO
Molluscum contagiosum virus (MCV) lesions from Spanish human immunodeficiency virus (HIV)-negative patients were clinically examined and analyzed for virus detection and typing. In a study of 147 patients, 97 (66%) were children under 10 years, of whom 49% had atopic dermatitis. MCV lesions were morphologically indistinguishable among the different age groups, but atopic patients presented larger lesions compared with patients without the disorder. In adults, lesions were observed mainly on the genitals. MCVI was the predominant subtype. The deduced MCVI/MCVII ratio (146:1) was much higher than that found in other geographical areas. Protein preparations of the virus-induced lesions were immunoblotted with sera from 25 MCVI patients. The host-serum antibody response was weak and variable, although no significant differences were found between atopic and nonatopic patients. Three immunoreactive proteins of 74/80, 60, and 35 kDa were detected in almost all the analyzed sera. The 35 and 74/80-kDa proteins were virus specific, whereas the 60-kDa protein band was composed of a mix of human keratins. Immunoblotting of MCV lesions and vaccinia virus-infected cell extracts with either MCV patient serum or a rabbit antiserum against vaccinia virus showed no cross-reactivity of these two human poxviruses at the antigenic level.