RESUMEN
AIMS: Bacterial community structure and composition of a drinking water network were assessed to better understand this ecosystem in relation to haloacetic acid (HAA) degradation and to identify new bacterial species having HAA degradation capacities. METHODS AND RESULTS: Biofilm samples were collected from a model system, simulating the end of the drinking water distribution network and supplied with different concentrations of dichloroacetic and trichloroacetic acids at different periods over the course of a year. The samples were analysed by culturing, denaturing gradient gel electrophoresis (DGGE) and sequencing. Pipe diameter and HAA ratios did not impact the bacterial community profiles, but the season had a clear influence. Based on DGGE profiles, it appeared that a particular biomass has developed during the summer compared with the other seasons. Among the bacteria isolated in this study, those from genus Cupriavidus were able to degrade dichloroacetic acid. Moreover, these bacteria degrade dichloroacetic acid at 18°C but not at 10°C. CONCLUSIONS: The microbial diversity evolved throughout the experiment, but the bacterial community was distinct during the summer. Results obtained on the capacity of Cupriavidus to degrade DCAA only at 18°C but not at 10°C indicate that water temperature is a major element affecting DCAA degradation and confirming observations made regarding season influence on HAA degradation in the drinking water distribution network. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first demonstration of the HAA biodegradation capacity of the genus Cupriavidus.
RESUMEN
HIPK2 is a eukaryotic Serine-Threonine kinase that controls cellular proliferation and survival in response to exogenous signals. Here, we show that the human transcription factor ZBTB4 is a new target of HIPK2. The two proteins interact in vitro, colocalize and associate in vivo, and HIPK2 phosphorylates several conserved residues of ZBTB4. Overexpressing HIPK2 causes the degradation of ZBTB4, whereas overexpressing a kinase-deficient mutant of HIPK2 has no effect. The chemical activation of HIPK2 also decreases the amount of ZBTB4 in cells. Conversely, the inhibition of HIPK2 by drugs or by RNA interference causes a large increase in ZBTB4 levels. This negative regulation of ZBTB4 by HIPK2 occurs under normal conditions of cell growth. In addition, the degradation is increased by DNA damage. These findings have two consequences. First, we have recently shown that ZBTB4 inhibits the transcription of p21. Therefore, the activation of p21 by HIPK2 is two-pronged: stimulation of the activator p53, and simultaneous repression of the inhibitor ZBTB4. Second, ZBTB4 is also known to bind methylated DNA and repress methylated sequences. Consequently, our findings raise the possibility that HIPK2 might influence the epigenetic regulation of gene expression at loci that remain to be identified.
Asunto(s)
Proteínas Portadoras/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Represoras/metabolismo , Secuencia de Aminoácidos , Animales , Western Blotting , Proteínas Portadoras/genética , Línea Celular Tumoral , Daño del ADN , Regulación hacia Abajo , Células HCT116 , Humanos , Inmunoprecipitación , Proteínas Luminiscentes/genética , Proteínas Luminiscentes/metabolismo , Ratones , Datos de Secuencia Molecular , Mutación , Células 3T3 NIH , Fosforilación , Unión Proteica , Proteínas Serina-Treonina Quinasas/genética , Interferencia de ARN , Proteínas Represoras/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Homología de Secuencia de Aminoácido , Treonina/metabolismo , Técnicas del Sistema de Dos HíbridosRESUMEN
Mammalian dosage compensation involves silencing of one of the two X chromosomes in females and is controlled by the X-inactivation center (Xic). The Xic, which includes Xist and its antisense transcription unit Tsix/Xite, somehow senses the number of X chromosomes and triggers Xist up-regulation from one of the two X chromosomes in females. We found that a segment of the mouse Xic lying several hundred kilobases upstream of Xist brings the two Xics together before the onset of X inactivation. This region can autonomously drive Xic trans-interactions even as an ectopic single-copy transgene. Its introduction into male embryonic stem cells is strongly selected against, consistent with a possible role in trans-activating Xist. We propose that homologous associations driven by this novel X-pairing region (Xpr) of the Xic enable a cell to sense that more than one X chromosome is present and coordinate reciprocal Xist/Tsix expression.
Asunto(s)
Emparejamiento Cromosómico , Inactivación del Cromosoma X , Cromosoma X/genética , Alelos , Animales , Diferenciación Celular , Línea Celular , Cromosomas Artificiales Bacterianos , Regulación hacia Abajo , Células Madre Embrionarias , Femenino , Ratones , Ratones Transgénicos , ARN Largo no Codificante , ARN no Traducido/genética , ARN no Traducido/metabolismo , Fase S , Transfección , Transgenes , Regulación hacia Arriba , Cromosoma X/fisiologíaRESUMEN
The process of well child care in public health clinics was evaluated using a peer review approach based on explicit criteria formulated by the peers themselves. The criteria defined what should be done in order to ensure good preventive care during a client-provider encounter. The data from this study suggest that the traditional goals of public health are being pursued, but that a broader spectrum of preventive care, including attention to the child's psychosocial development, is still lacking.