RESUMO
Retrotransposons are mobile genetic elements. They can transpose via the reverse transcription of mRNA into double-stranded DNA (dsDNA) followed by the insertion of this dsDNA into new sites within the host genome. The unintegrated, linear, dsDNA form of retrotransposons is usually very rare. We report here the isolation of a retrotransposon from Candida albicans which is unusual in this respect. This element, which we have named pCal, was first identified as a distinct band when uncut C. albicans DNA was examined on an agarose gel. Sequence analysis of the cloned element revealed that it is a retrotransposon belonging to the Ty1/copia group. It is estimated that pCal produces 50 to 100 free, linear, dsDNA copies of itself per cell. This is a much higher level of expression than even that of the system in which Ty1 is expressed behind the highly active GAL1 promoter on a high-copy-number plasmid (about 10 copies per cell). Another unusual feature of pCal is that its Pol enzymes are likely to be expressed via the pseudoknot-assisted suppression of an upstream, in-phase stop codon, as has been shown for Moloney murine leukemia virus.
Assuntos
Candida albicans/genética , Elementos de DNA Transponíveis/genética , Retroelementos , Sequência de Aminoácidos , Sequência de Bases , Mapeamento Cromossômico , Clonagem Molecular , Códon de Terminação , DNA Fúngico/análise , DNA Fúngico/genética , DNA Fúngico/isolamento & purificação , Endopeptidases/genética , Regulação Fúngica da Expressão Gênica , Produtos do Gene pol/genética , Produtos do Gene pol/metabolismo , Integrases/genética , Dados de Sequência Molecular , Estrutura Molecular , Fases de Leitura Aberta , Filogenia , Plasmídeos , Regiões Promotoras Genéticas , DNA Polimerase Dirigida por RNA/genética , Ribonucleases/genética , Alinhamento de Sequência , Análise de Sequência de DNA , Homologia de Sequência de AminoácidosRESUMO
This paper describes the use of the terephthalate dosimeter to measure the threshold and extent of cavitation arising from medical ultrasound sources at high frequencies. Significant hydroxyl radical production was noted from a physiotherapy source and low level activity was also detected when using a pulsed, diagnostic type transducer system. The effect of sound intensity and the type of field is described. The possibility of using polymer degradation to monitor the cavitation is also discussed.
Assuntos
Ácidos Ftálicos , Monitoramento de Radiação/métodos , Ultrassom , Ultrassonografia , Calibragem , Sequestradores de Radicais Livres , Radical Hidroxila , Monitoramento de Radiação/instrumentação , Sensibilidade e EspecificidadeRESUMO
This study compared the effectiveness of a rap video with a traditional video in providing nutrition information. Sixty pregnant African-American females (ages 14 through 18) were randomly assigned to view either a rap video or a traditional video about good nutrition. The data revealed no significant difference in scores between the two versions; both videos produced significant learning; and 17 and 18 year olds scored higher than 15 and 16 year olds.
Assuntos
Música , Ciências da Nutrição/educação , Ensino/métodos , Adolescente , Humanos , Estados UnidosRESUMO
Nineteen linkage groups containing a total of 52 markers have been identified in the sheep genome after typing large paternal half-sib families. The linkage groups range in size from 2 markers showing no recombination to a group containing 6 markers covering approximately 30 cM of the sheep genome. Thirteen of the groups have been assigned to a sheep chromosome. Three groups contain markers from bovine syntenic groups U2, U7 and U29, and one other group contains a marker that has been mapped only in humans. The remaining three groups are unassigned. This information will provide a useful foundation for a genetic linkage map of sheep.
