Revisando la inactivación del cromosoma X y su impacto en la longevidad femenina

La inactivación del cromosoma X es el mecanismo genético por el cual la expresión génica ligada al X se iguala entre los géneros masculinos y femeninos de todas las especies de mamíferos placentarios. Dado que la probabilidad de expresión de alelo ligado a X mutante disminuye como resultado de la inactivación, se ha propuesto que las hembras tienen ventajas biológicas en relación con los machos. Estas ventajas han captado la atención de la comunidad científica en los últimos años y la han centrado en este tema y sus implicaciones clínicas. Para arrojar algo de luz sobre este fenómeno intrigante, este artículo revisa los eventos moleculares más relevantes involucrados en este proceso. Estos eventos incluyen el papel de Xist , el mecanismo de selección para la futura inactivación del cromosoma X, la inactivación relacionada con la edadsesgo y la relación entre la inactivación y la aparición de enfermedades ligadas al cromosoma X, posibles tratamientos y longevidad.X-chromosome inactivation is the genetic mechanism by which X-linked gene expression is equalized between the male and female genders of all placental mammal species. Given that the probability of mutant X-linked allele expression decreases as a result of the inactivation, it has been proposed that females have biological advantages relative to males. These advantages have grabbed the attention of the scientific community in recent years and have focused it on this topic and its clinical implications. To shed some new light on this intriguing phenomenon, this article reviews the most relevant molecular events involved in this process. These events include the role of Xist, the selection mechanism for future X-chromosome inactivation, the age-related inactivation skewing, and the relationship between inactivation and the emergence of X-linked diseases, possible treatments, and longevit

Preliminary population study of Methylenetetrahydrofolate Reductase (MTHFR) C677T polymorphism determination in a pilot group of students from the University of Rosario

Introducción: la 5, 10-metilentetrahidrofolato reductasa (MTHFR) es una enzima clave en el metabolismo del folato; sus polimorfismos se han asociado al aumento de riesgo de padecer enfermedad coronaria, problemas obstétricos en mujeres gestantes, desarrollo de fetos con defectos de cierre del tubo neural y susceptibilidad a algunos tipos de cáncer. Este gen presenta una variación polimórfica de nucleótido único, que consiste en un cambio de C por T en la posición 677 el cual afecta de manera notable su actividad enzimática. Objetivo: Dada la importancia de esta enzima y la heterogeneidad genética de la población colombiana se realizó un estudio para determinar las frecuencias alélicas y genotípicas del polimorfismo C677T de MTHFR en individuos sanos, debido a que en el país sólo se han realizado estudios que involucran metodología de casos y controles. Materiales y métodos: Este polimorfismo se estudió a partir de ADN de una muestra poblacional de 206 estudiantes. Adicionalmente, se calcularon las frecuencias globales de Colombia utilizando los datos de controles sanos reportados en otros estudios. Resultados: En la muestra evaluada se detectó un desequilibrio Hardy-Weinberg, mientras que en los datos globales colombianos se encontró que la población está en equilibrio. Conclusión: la frecuencia poblacional del alelo T parece estar sometida a una presión de selección positiva, dado su incremento en la población a pesar de su efecto deletéreo. Un estudio español reporta resultados similares y argumenta como causa probable de este cambio en la frecuencia alélica de T la suplementación con ácido fólico a futuras madres. Introduction: the 5, 10-methylenetetrahydrofolate reductase (MTHFR) is an essential enzyme in folate metabolism; their polymorphisms have been associated with heart disease risk increase, obstetric problems, neural tube defects in fetuses and cancer susceptibility. This gene has a single nucleotide polymorphism, a C-T change at nucleotide 677, which affects significantly its enzymatic activity. Objective: because of the biological importance of this enzyme and the Colombian population genetic heterogeneity characteristic, a study was performed to determine allele and genotype frequencies of MTHFR C677T polymorphism in healthy individuals, taking into account that in Colombia there are only studies that have involved case-control methodology. Methods: we analyzed this polymorphism trough the amplification of the DNA of a 206 students sample population. Additionally, Colombian overall frequencies were calculated, using data from healthy controls reported in other studies. Results: a Hardy-Weinberg disequilibri m was found in the sample tested. For the Colombian data, we found that the global population was in equilibrium. Conclusion: T allele population frequency seems to be under positive selection pressure, which is reflected in the population allele increase, despite its deleterious effect. A Spanish study reported similar results and identified folic acid supplementation on expectant mothers as a probably cause of this change.

Chromosomal instability in farmers exposed to pesticides: High prevalence of clonal and non-clonal chromosomal alterations

Introduction: An important economic activity in Colombia is agricultural production and farmers are frequently exposed to pesticides. Occupational exposure to pesticides is associated with an increased incidence of various diseases, including cancer, Parkinson’s disease, Alzheimer’s disease, reproductive disorders, and birth defects. However, although high genotoxicity is associated with these chemicals, information about the type and frequency of specific chromosomal alterations (CAs) and the level of chromosomal instability (CIN) induced by exposure to pesticides is scarce or absent. Methods: In this study, CAs and CIN were assessed in peripheral blood lymphocytes (PBLs) from five farmers occupationally exposed to pesticides and from five unexposed individuals using GTG-banding and molecular cytogenetic analysis. Results: A significant increase in clonal and non-clonal chromosomal alterations was observed in pesticide-exposed individuals compared with unexposed individuals (510±12,2 vs 73±5,7, respectively; p less than 0.008). Among all CAs, monosomies and deletions were more frequently observed in the exposed group. Also, a high frequency of fragilities was observed in the exposed group. Conclusion: Together, these findings suggest that exposure to pesticides could be associated with CIN in PBLs and indicate the need for the establishment of educational programs on safety precautions when handling pesticides, such as wearing gloves, masks and boots, changing clothes and maintaining proper hygiene, among others. Further evaluation in other similar studies that include a greater number of individuals exposed to pesticides is necessary. © 2020 Cepeda et al

Biodiversity in the Amazon: Origin Hypotheses, Intrinsic Capacity of Species Colonization, and Comparative Phylogeography of River Otters (Lontra longicaudis and Pteronura brasiliensis, Mustelidae, Carnivora) and Pink River Dolphin (Inia sp., Iniidae, Cetacea)

We sequenced mitochondrial genes of otter (Lontra longicaudis and Pteronura brasiliensis) and dolphin (Inia sp.) species to provide new systematics data and to test hypotheses that offer explanations as to the Amazon’s biodiversity. Four of the 11 hypotheses tested --Paleogeography (PH), Recent Lagoon (RLH), Hydrogeological Recent Change (HRCH), and Refugia (RH)-- support the evolution of these three species. As part of this comparative phylogenetic study, we also considered the degree of water dependence of each species. For the least water dependent of the three species, L. longicaudis, only HRCH and RH had an influence on genetic structure, although it was relatively minor. For the more water dependent otter species, P. brasiliensis, our analyses stressed the significance of a single PH event along with two lesser important PH events. However, its gene diversification basically occurred during the Pleistocene and our analyses did detect a relatively small influence of HRCH and RH. For the completely water dependent species, Inia, we detected two significant PH events. Its genetic structure was considerably more developed than in either otter species, although the Pleistocene was a very important period of genetic diversification for the pink river dolphins (HRCH and RLH). Each species has ancestors with different geographical origins and genomes with different capacities to colonize—making it difficult to rely on a generalized hypothesis to understand the origins of the Amazon’s extremely rich biodiversity. © 2017, Springer Science+Business Media New York

Divulgación Científica No.4

En las instituciones encargadas de adelantar proyectos de investigación, como es el caso de la universidad, debemos reflexionar sobre lo que hacemos y sus implicaciones, de tal forma que encontremos claves para propiciar, desde nuestros saberes, agentes dinamizadores que animen la discusión, el debate y la comparación. Lo anterior con el enfoque de proponer caminos y soluciones para problemas actuales que nos aquejan como individuos. Las distintas búsquedas que hacemos apuntan a contribuir a la construcción de mejores sociedades, y la investigación es una valiosa herramienta con a que contamos para lograrlo. Es necesario entender la investigación como un agente que permite y propicia cambios.In the institutions in charge of carrying out research projects, such as the university, we must reflect on what we do and its implications, in such a way that we find keys to promote, from our knowledge, dynamic agents that encourage discussion, debate and the comparison. The above with the focus of proposing paths and solutions for current problems that afflict us as individuals. The different searches that we do aim to contribute to the construction of better societies, and research is a valuable tool that we have to achieve it. It is necessary to understand research as an agent that allows and promotes changes

Divulgación Científica No.4

En las instituciones encargadas de adelantar proyectos de investigación, como es el caso de la universidad, debemos reflexionar sobre lo que hacemos y sus implicaciones, de tal forma que encontremos claves para propiciar, desde nuestros saberes, agentes dinamizadores que animen la discusión, el debate y la comparación. Lo anterior con el enfoque de proponer caminos y soluciones para problemas actuales que nos aquejan como individuos. Las distintas búsquedas que hacemos apuntan a contribuir a la construcción de mejores sociedades, y la investigación es una valiosa herramienta con a que contamos para lograrlo. Es necesario entender la investigación como un agente que permite y propicia cambios.In the institutions in charge of carrying out research projects, such as the university, we must reflect on what we do and its implications, in such a way that we find keys to promote, from our knowledge, dynamic agents that encourage discussion, debate and the comparison. The above with the focus of proposing paths and solutions for current problems that afflict us as individuals. The different searches that we do aim to contribute to the construction of better societies, and research is a valuable tool that we have to achieve it. It is necessary to understand research as an agent that allows and promotes changes