RESUMO
Dysregulation of oncogenes by translocation to an IgH (14q32) or IgL (kappa, 2p11 or lambda, 22q11) locus is a frequent event in the pathogenesis of B-cell tumors. Translocations involving an IgH locus and a diverse but nonrandom array of chromosomal loci occur in most multiple myeloma (MM) tumors even though the translocations often are not detected by conventional cytogenetic analysis. In a continuing analysis of translocations in 21 MM lines, we show that the novel, karyotypically silent t(14;16)(q32.3;q23) translocation is present in 5 MM lines, with cloned breakpoints from 4 lines dispersed over an approximately 500-kb region centromeric to the c-maf proto-oncogene at 16q23. Another line has a t(16;22)(q23;q11), with the breakpoint telomeric to c-maf, so that the translocation breakpoints in these 6 lines bracket c-maf. Only these 6 lines overexpress c-maf mRNA. As predicted for dysregulation of c-maf by translocation, there is selective expression of one c-maf allele in 2 informative lines with translocations. This is the first human tumor in which the basic zipper c-maf transcription factor is shown to function as an oncogene.
Assuntos
Cromossomos Humanos Par 14 , Cromossomos Humanos Par 16 , Proteínas de Ligação a DNA/genética , Cadeias Pesadas de Imunoglobulinas/genética , Mieloma Múltiplo/genética , Proteínas Proto-Oncogênicas/genética , Translocação Genética , Sequência de Aminoácidos , Cromossomos Artificiais de Levedura , Regulação Neoplásica da Expressão Gênica , Genes de Imunoglobulinas , Humanos , Hibridização in Situ Fluorescente , Dados de Sequência Molecular , Proto-Oncogene Mas , Proteínas Proto-Oncogênicas c-maf , Células Tumorais CultivadasRESUMO
Four classes of Xanthomonas campestris mutants were identified with respect to pectate lyase. Pectate lyase production in the wild-type and classes I and IIb mutants was partially dependent on the growth-phase whereas in classes IIa and III it was totally dependent. Enzyme activity in some of the mutants was constitutive and resistant to catabolite repression.
RESUMO
Four hundred and eight apparently healthy school children from rural primary schools in Ile-Ife were examined for the prevalence of Salmonella and Shigella species, which were found respectively in 2% and 3.2% of these children. The prevalence of the organisms decreased as the age of the children increased. Salmonella species were found only in specimens from boys while Shigella species occurred in both sexes and were more prevalent among females. No specimen contained both organisms. Only one of the 12 different sources of well and rain water used for domestic purposes in the rural areas where the children examined lived contained Salmonella species, and none contained any species of Shigella or faecal E. coli.
