ABSTRACT
En los organismos diploides, cada gen autosómico está representado por dos copias, o alelos, heredados de cada progenitor al momento de la fecundación. Para la gran mayoría de los genes la expresión ocurre desde ambos alelos de manera simultánea. Sin embargo, un número reducido de genes (menos del 1%) es afectado por un proceso de impronta genómica. Este proceso determina que la expresión del gen sea dependiente del origen parental, es decir, se comporte de manera distinta si su origen es materno o paterno. La metilación del ADN es una de las modificaciones epigenéticas mejor estudiadas y su participación resulta esencial durante el establecimiento de la impronta genómica. Si bien los patrones de metilación a nivel genómico son estables y heredables, existen al menos dos períodos del desarrollo embrionario de mamíferos durante los cuales los patrones de metilación globales son borrados y re-establecidos. Estos dos períodos del desarrollo coinciden con el borrado y establecimiento de la impronta genómica específica de cada individuo. Desde el punto de vista funcional, la mayoría de los genes sometidos a impronta cumplen roles en el control del crecimiento y desarrollo embrionario y placentario. Alteraciones en el patrón de expresión de ellos han sido relacionados a patologías tales como el Síndrome de Algelman y el Síndrome de Prader-Willi, entre otros.
In diploid organisms, autosomal genes are composed of two copies, or alleles, inherited from both parents at fertilization. For the vast majority of autosomal genes, expression occurs from both alleles simultaneously. However, a small proportion (<1%) of genes are imprinted, meaning that their expression depends on the parental origin . DNA methylation is one of the most known epigenetic modifications and its function is critical for the establishment of imprinting. The global pattern of genomic methylation is stable and inheritable, however, it is erased and re-established in a sex-depended manner at two critical periods of embryonic development. Functionally, the majority of imprinted genes play roles in the control of embryonic and placental growth and development. Alterations in imprinted genes have been correlated with several pathologies including the Angelman and Prader-Willi syndromes.
Subject(s)
Humans , Animals , Genomic Imprinting , DNA Methylation , Epigenesis, Genetic , Embryonic Development/geneticsABSTRACT
Background: In Chile, residency training programs (RTP) take place in a stimulating academic environment for the promotion of clinical research skills. However, research is not a frequent curricular outcome. Accreditation of these programs by the National Accreditation Commission is an opportunity to improve the trainee's research competences. Aim: To analyze in the RTP curricula, the explicit intention to carry out clinical research and its correlation with the scientific productivity of professors and residents. Material and Methods: Fifty six training study programs corresponding to six primary specialties and six derived specialties, offered by seven universities holding accreditation tenure for RTP from the Chilean Association of Medicine Faculties (ASOFAMECH) up to 2005, were analyzed. The analysis included each academic program, courses and/or rotations and professors and residents' productivity, measured as publications accredited in the Institute for Scientific Information (ISI), between 1999 and 2007. Results: RTP are based on a tutorial educational model, where the close relationship between professors and residents is essential for the expected final outcome. Simultaneously, the programs' curricula revealed a high intentionality towards clinical research. However, professors' publications of ISI indexed articles showed a low and irregular scientific productivity. Conclusions: The gap between the declared training in clinical research and the effective ISI productivity is an awareness call with respect to the contribution that RTP could provide to accreditation, to professors and residents, and in general to health improvement in the country.