RESUMEN
Somatic cell nuclear transfer technology has been applied to produce live clones successfully in several mammalian species, but the success rates are very low. In mice, about half of the nuclear transfer embryos undergo implantation, but very few survive to term. We undertook detailed histological analyses of placentas from cloned mouse embryos generated from cumulus cells at 10.5 dpc of pregnancy, by which stage most clones have terminated their development. At 10.5 dpc, the extraembryonic tissues displayed several defined histological patterns, each reflecting their stage of developmental arrest. The most notable abnormality was the poor development of the spongiotrophoblast layer of diploid cells. This is in contrast to the placental hyperplasia frequently observed in somatic clones at 12.5 dpc or later stages. A variety of structural abnormalities were also observed in the embryos. Both placental and embryonic defects likely contribute to the low success rate of the mouse clones.
Asunto(s)
Membrana Corioalantoides/metabolismo , Clonación de Organismos/métodos , Técnicas de Cultivo de Embriones , Placenta/metabolismo , Animales , Núcleo Celular/metabolismo , Desarrollo Embrionario , Femenino , Hibridación in Situ , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos DBA , Enfermedades Placentarias/genética , Embarazo , PreñezRESUMEN
By comparing mammalian genomes, we and others have identified actively transcribed Ty3/gypsy retrotransposon-derived genes with highly conserved DNA sequences and insertion sites. To elucidate the functions of evolutionarily conserved retrotransposon-derived genes in mammalian development, we produced mice that lack one of these genes, Peg10 (paternally expressed 10), which is a paternally expressed imprinted gene on mouse proximal chromosome 6. The Peg10 knockout mice showed early embryonic lethality owing to defects in the placenta. This indicates that Peg10 is critical for mouse parthenogenetic development and provides the first direct evidence of an essential role of an evolutionarily conserved retrotransposon-derived gene in mammalian development.
Asunto(s)
Pérdida del Embrión/genética , Impresión Genómica , Proteínas Nucleares/genética , Placenta/patología , Retroelementos , Factores de Transcripción/genética , Animales , Proteínas Reguladoras de la Apoptosis , Metilación de ADN , Proteínas de Unión al ADN , Femenino , Retardo del Crecimiento Fetal/genética , Eliminación de Gen , Regulación del Desarrollo de la Expresión Génica , Ratones , Ratones Noqueados , Proteínas Nucleares/metabolismo , Partenogénesis/genética , Placenta/fisiología , Embarazo , Proteínas de Unión al ARN , Factores de Transcripción/metabolismoRESUMEN
The Meg1/Grb10 protein has been implicated as an adapter protein in the signaling pathways from insulin receptor (IR) and insulin-like growth factor 1 receptor (IGF1R) in vitro. To elucidate its in vivo function, four independent Meg1/Grb10 transgenic mouse lines were established, and the effects of excess Meg1/Grb10 on both postnatal growth and glucose metabolism were examined. All of the Meg1/Grb10 transgenic mice showed growth retardation after weaning (3-4 weeks), which indicates that ectopic overexpression of Meg1/Grb10 inhibits postnatal growth that is mediated by IGF1 via IGF1R. In addition, the mice became hyperinsulinemic owing to high levels of insulin resistance, which demonstrates that Meg1/Grb10 also modulates the insulin receptor cascade negatively in vivo. Type II diabetes arose frequently in the two transgenic lines, which also showed impaired glucose tolerance. In these mice, severe atrophy of the pancreatic acinus cells was associated with high-level production of Meg1/Grb10 in the pancreas. These results suggest that Meg1/Grb10 inhibits the function of both insulin and IGF1 receptors in these cells, since a similar phenotype has been reported for Ir and Igf1r double knockout mice. Taken together, these results indicate that Meg1/Grb10 interacts with both insulin and IGF1 receptors in vivo, and negatively regulates the IGF growth pathways via these receptors.
Asunto(s)
Glucosa/metabolismo , Trastornos del Crecimiento/metabolismo , Resistencia a la Insulina , Insulina/metabolismo , Proteínas/metabolismo , Receptor IGF Tipo 1/metabolismo , Receptor de Insulina/metabolismo , Animales , Animales Recién Nacidos , Regulación hacia Abajo , Proteína Adaptadora GRB10 , Ratones , Ratones Endogámicos C3H , Ratones Transgénicos/metabolismo , Especificidad de Órganos , Ingeniería de Proteínas/métodos , Proteínas Recombinantes/metabolismo , Distribución TisularRESUMEN
Shiga toxin (Stx)-producing Escherichia coli (STEC), an important cause of hemolytic uremic syndrome, was completely killed by (60)Co irradiation at 1 x l0(3) gray (1 kGy) or higher. However, a low dose of irradiation (0.1-0.3 kGy) markedly induced Stx phage from STEC. Stx production was observed in parallel to the phage induction. Inactivation of Stx phage required a higher irradiation dose than that for bacterial killing. Regarding Stx, cytotoxicity was susceptible to irradiation, but cytokine induction activity was more resistant than Stx phage. The findings suggest that (1). although (60)Co irradiation is an effective means to kill the bacteria, it does induce Stx phage at a lower irradiation dose, with a risk of Stx phage transfer and emergence of new Stx-producing strains, and (2). irradiation differentially inactivates some activities of Stx.
Asunto(s)
Bacteriófagos/efectos de la radiación , Escherichia coli/efectos de la radiación , Escherichia coli/virología , Contaminación de Alimentos/prevención & control , Toxina Shiga/biosíntesis , Animales , Bacteriófagos/crecimiento & desarrollo , Bacteriófagos/metabolismo , Bovinos , Radioisótopos de Cobalto , ADN Bacteriano/efectos de la radiación , Escherichia coli/metabolismo , Humanos , Plásmidos/efectos de la radiaciónRESUMEN
BACKGROUND: Clarithromycin-resistant Helicobacter pylori (CRHP) is increasing worldwide. Clarithromycin resistance in H. pylori from familial members has not been investigated. MATERIALS AND METHODS: Biopsy specimens were taken from 13 families living in Tokyo, Yokohama, and Niigata between 1998 and 2001. Drug resistance was tested with the replica plating method. The minimum inhibitory concentrations of antimicrobial agents for H. pylori strains were determined by the agar dilution method. Molecular analyses of H. pylori strains were performed by ribosomal RNA gene restriction pattern analysis. The DNA region, associated with clarithromycin resistance, was analyzed by PCR and sequencing. RESULTS: Helicobacter pylori strains isolated from a 5-year-old-son displayed clarithromycin resistance with a mutation (A --> G at position 2143) in the 23S ribosomal RNA, whereas H. pylori strains from his parents did not. DNA analyses revealed that the boy was infected with his father's strain. The boy had repeatedly developed otitis media and received clarithromycin since the age of 2 years. Studies on an additional 12 families demonstrated that clarithromycin resistance in the children's strains reached 42.9% and was significantly higher than those of H. pylori strains from their parents (0%) or from adult patients (11.1%) (p <.05). CONCLUSIONS: The rate of clarithromycin resistance in H. pylori strains from Japanese children was extremely high, in contrast to those from their parents or adult patients. Prior history of clarithromycin usage in a child suggested development of clarithromycin resistance in resident H. pylori, which was originated from a parent.
Asunto(s)
Antibacterianos/farmacología , Claritromicina/farmacología , Farmacorresistencia Bacteriana/genética , Infecciones por Helicobacter/epidemiología , Helicobacter pylori/efectos de los fármacos , Adulto , Niño , Preescolar , ADN Ribosómico/análisis , Familia , Femenino , Infecciones por Helicobacter/microbiología , Infecciones por Helicobacter/transmisión , Humanos , Masculino , Pruebas de Sensibilidad Microbiana , Padres , Prevalencia , ARN Ribosómico 23S/genética , Ribotipificación , Análisis de Secuencia de ADNRESUMEN
Shiga toxin-producing Escherichia coli (STEC) is associated with hemolytic uremic syndrome (HUS). Although most clinical isolates of STEC produce hemolysin (called enterohemolysin), the precise role of enterohemolysin in the pathogenesis of STEC infections is unknown. Here we demonstrated that E. coli carrying the cloned enterohemolysin operon (hlyC, A, B, D genes) from an STEC human strain induced the production of interleukin-1beta (IL-1beta) through its mRNA expression but not tumor necrosis factor-alpha from human monocytes. No IL-1beta release was observed with an enterohemolysin (HlyA)-negative, isogenic E. coli strain carrying a mutation in the hlyA gene. The data suggest that enterohemolysin, a pore-forming toxin, induces the production of IL-1beta, which is one of serum risk markers for HUS.