RESUMO
The sex chromosome constitution of the silkworm, Bombyx mori, is ZW in the female and ZZ in the male. Very little molecular information is available about the Z chromosome in Lepidoptera, although the topic is interesting because of the absence of gene dosage compensation in this chromosome. We constructed a 320-kb BAC contig around the Bmkettin gene on the Z chromosome in Bombyx and determined its nucleotide sequence by the shotgun method. We found 13 novel protein-coding sequences in addition to Bmkettin. All the transposable elements detected in the region were truncated, and no LTR retrotransposons were found, in stark contrast to the situation on the W chromosome. In this 320-kb region, four genes for muscle proteins (Bmkettin, Bmtitin1, Bmtitin2, and Bmprojectin) are clustered, together with another gene (Bmmiple) on the Z chromosome in B. mori; their orthologs are also closely linked on chromosome 3 in Drosophila, suggesting a partial synteny. Real-time RT-PCR experiments demonstrated that transcripts of 13 genes of the 14 Z-linked genes found accumulated in larger amounts in males than in female moths, indicating the absence of gene dosage compensation. The implications of these findings for the evolution and function of the Z chromosome in Lepidoptera are discussed.
Assuntos
Bombyx/genética , Proteínas de Drosophila , Genes de Insetos , Proteínas de Insetos/genética , Proteínas Musculares/genética , Cromossomos Sexuais/genética , Motivos de Aminoácidos , Sequência de Aminoácidos , Animais , Sequência de Bases , Mapeamento Cromossômico , Passeio de Cromossomo , Cromossomos Artificiais Bacterianos/genética , Conectina , Mapeamento de Sequências Contíguas , Etiquetas de Sequências Expressas , Feminino , Biblioteca Gênica , Masculino , Dados de Sequência Molecular , Análise de Sequência de DNA , Caracteres SexuaisAssuntos
Cromossomos/genética , Impressão Genômica , Animais , Bacteriófago P1/genética , Mapeamento de Sequências Contíguas , DNA/química , DNA/genética , Biblioteca Genômica , Camundongos , Camundongos Endogâmicos , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Análise de Sequência de DNARESUMO
The mouse gene U2 auxiliary factor binding protein related sequence (U2afbp-rs) has previously been shown to be genomically imprinted with monoallelic expression from the paternal allele. To determine if the human homologue is imprinted and contains conserved structural features which regulate imprinting, we isolated genomic clones from a human P1-derived artificial chromosome (PAC) library that map to human chromosome 5q22-31, a region syntenic to the proximal portion of mouse chromosome 11 where U2afbp-rs resides. A genomic subclone was isolated which contained an open reading frame with high homology to the mouse gene. This subclone also maintained the intronless character of the mouse gene. A KpnI polymorphism within the open reading frame of the gene was found to occur in 21% (8/38) of the alleles tested from human placental tissue samples. RT-PCR analysis of human placentas using the KpnI polymorphism to determine the parental origin of the alleles indicates biallelic expression of the human chromosome 5 U2AFBPL gene.
Assuntos
Impressão Genômica , Proteínas do Tecido Nervoso , Proteínas Nucleares , Ribonucleoproteínas/genética , Alelos , Animais , Cromossomos Humanos Par 5 , Primers do DNA/química , Genes , Humanos , Camundongos , Placenta/fisiologia , Sequências Repetitivas de Ácido Nucleico , Mapeamento por Restrição , Ribonucleoproteínas Nucleares Pequenas , Fator de Processamento U2AFRESUMO
The role of genomic alterations in mutagenesis induced by ionizing radiation has been the subject of considerable speculation. By Southern blotting analysis we show here that 9 of 55 (approximately 1/6) gamma-ray-induced mutants at the adenine phosphoribosyl transferase (aprt) locus of Chinese hamster ovary (CHO) cells have a detectable genomic rearrangement. These fall into two classes: intragenic deletions and chromosomal rearrangements. In contrast, no major genomic alterations were detected among 67 spontaneous mutants, although two restriction site loss events were observed. Three gamma-ray-induced mutants were found to be intragenic deletions; all may have identical break-points. The remaining six gamma-ray-induced mutants demonstrating a genomic alteration appear to be the result of chromosomal rearrangements, possibly translocation or inversion events. None of the remaining gamma-ray-induced mutants showed any observable alteration in blotting pattern indicating a substantial role for point mutation in gamma-ray-induced mutagenesis at the aprt locus.
Assuntos
Adenina Fosforribosiltransferase/genética , Genes/efeitos da radiação , Mutação , Pentosiltransferases/genética , Animais , Linhagem Celular , Cricetinae , Cricetulus , DNA/isolamento & purificação , Enzimas de Restrição do DNA , Feminino , Peso Molecular , Hibridização de Ácido Nucleico , OvárioRESUMO
Streptomyces griseus ATCC 10137 synthesizes about 1 IU of L-asparaginase/100 ml of a 4% peptone medium. The enzyme has a pH optimum of 8.5 which is comparable to that of the L-asparaginase derived from Escherichia coli which has antitumor properties.