Asunto(s)
Erradicación de la Enfermedad/organización & administración , Infecciones por VIH/epidemiología , Infecciones por VIH/prevención & control , Accesibilidad a los Servicios de Salud/organización & administración , Síndrome de Inmunodeficiencia Adquirida/epidemiología , Síndrome de Inmunodeficiencia Adquirida/prevención & control , Antirretrovirales/uso terapéutico , Financiación Gubernamental/organización & administración , Infecciones por VIH/diagnóstico , Infecciones por VIH/tratamiento farmacológico , Humanos , Liderazgo , Política , Grupos Raciales , Minorías Sexuales y de Género , Estigma Social , Factores Socioeconómicos , Estados UnidosRESUMEN
The effect that different regions of the Alu consensus sequence have upon the stability and accumulation of its RNA polymerase III (Pol III) directed transcripts was determined by transiently overexpressing Alu deletion and chimeric constructs in human 293 cells. Transcripts of the left Alu monomer are more stable than those of the full-length consensus sequence and any additional 3' sequence beyond the left monomer destabilizes the resulting transcript. Neither the middle A-rich region nor the 3' A-rich tail specifically affect the stability of Alu transcripts. However, the right monomer is inherently less stable than corresponding left monomer transcripts. Alu's dimeric structure and sequences peculiar to the right monomer each limit the stability and steady state accumulation of its transcripts. A host requirement to rapidly metabolize Alu RNA or restrict its abundance may have selected for these two features of the Alu consensus sequence.
Asunto(s)
Elementos Alu/genética , Transcripción Genética/genética , Animales , Northern Blotting , Línea Celular , ADN/química , ADN/genética , Dimerización , Expresión Génica , Humanos , Ratones , Plásmidos/genética , ARN/genética , ARN/metabolismo , Estabilidad del ARN , Elementos de Nucleótido Esparcido Corto/genéticaRESUMEN
Human Alu and adenovirus VA1 RNAs each stimulate the translational expression of reporter genes in co-transient transfection assays without affecting either the rate of global protein synthesis or the abundance of the reporter mRNA. This selective, post-transcriptional stimulation of expression, which is observed in human and mouse cell lines and for three reporters, acts through a PKR- independent mechanism. The activity of Alu and VA1 RNAs in this assay is transient, causing a reduction in the lag time for the translational expression of the newly synthesized reporter mRNAs. The reduction in this lag time accounts for the relative selectivity of the effect upon the expression of the reporter and suggests novel roles for Alu and VA1 RNA in cell stress recovery and viral infection. Deletion analysis demonstrates that a specific region residing within the right monomer of the dimeric Alu consensus sequence is necessary for activity. Highly abundant left Alu monomer transcripts are inactive but the right Alu monomer is fully active, although its transcripts are scarce. Mouse B1 and B2 SINE RNAs stimulate reporter gene expression in mouse cells, suggesting that this activity is a general property of eucaryotic SINEs.
Asunto(s)
Elementos Alu/genética , Biosíntesis de Proteínas/genética , ARN/metabolismo , Adenoviridae/genética , Animales , Línea Celular , Regulación de la Expresión Génica , Células HeLa , Humanos , Luciferasas/genética , Luciferasas/metabolismo , Ratones , Ratones Noqueados , Datos de Secuencia Molecular , Conformación de Ácido Nucleico , Plásmidos/genética , ARN/química , ARN/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , ARN Viral/genética , ARN Viral/metabolismo , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismo , Transfección , eIF-2 Quinasa/genética , eIF-2 Quinasa/metabolismoRESUMEN
Abstract- This article evaluates the use of DNA hybridization for estimating the extent of divergence among the single-copy fractions of vertebrate genomes. It focuses, in particular, on the nature and informational content of the melting profiles as a guide to phylogenetic relationships. While concluding that the DNA hybridization approach remains the best and most cost-effective guide to such relationships over its useful range, it demonstrates serious flaws in certain recent attempts to apply the method to specific cases among primates and birds. The major points are: 1 The T50 H statistic is flawed as a measure of mean sequence divergence, and also, therefore, as a measure of phylogenetic distance. 2 The Tmode statistic overcomes many of the problems inherent in interpreting thermal stabilities of DNA heteroduplexes for phylogenetic purposes. 3 The phylogenetic significance of ΔTmodes of > 15dÌ or so cannot be accurately assessed. 4 The putative slowdown in the rate of nuclear DNA sequence change among the lemurs is not justified by the data. 5 The claims of Sibley and Ahlquist to have resolved the human/chimpanzee/gorilla trichotomy are not supported by their data. 6 There are major problems in the published Sibley and Ahlquist avian phylogenies; in particular, with those containing evolutionary "staircases" of nodes separated by less than 1dÌ from one another. 7 There would appear to be a lineage misplacement involving a ΔT of at least 4dÌ in a recent publication on avian phylogeny. 8 Certain of the published ΔT50 H values seem not to be representative of the actual data on which they are based. 9 Most important, it is recommended that no phytogenies based on DNA hybridization comparisons should be presented without being accompanied by the data relevant to each claim of a resolved lineage.
