Adaptive responses in Chlamydomonas reinhardtii

The photosynthetic single cellular alga Chlamydomonas reinhardtii has been used as a model organism to examine in detail the physiological, biochemical and molecular processes of photosynthesis, flagella synthesis and movement, mineral stress, interactions between nucleus, chloroplasts and mitochondria and other processes. In this review we summarize part of the current knowledge on adaptive responses in C. reinhardtii when it is exposed to oxidative stress and to changes in light intensity, concentration of minerals, herbicides and metals. The individual responses are linked in order to understand the response of the cell, which is continuously subjected to fluctuations, as a whole

Epidemiología molecular y caracterización de genes de virulencia de aislados de estafilococo aureus resistentes a la meticilina adquiridos en la comunidad y adquiridos en el hospital en Colombia

Objective: To determine the molecular epidemiology and presence of virulence genes in communityacquired (CA) and hospital-acquired (HA) methicillin-resistant Staphylococcus aureus (MRSA) isolates and their relationship to clinical outcomes. Methods: An observational and prospective study of infections caused by MRSA was conducted between June 2006 and December 2007 across seven hospitals in three Colombian cities. MRSA isolates were analyzed for SCCmec. Also, pulsed-field gel electrophoresis and multilocus sequence typing were performed and 25 virulence genes were identified. Results: Two hundred and seventy isolates were collected from 262 adult hospital patients with MRSA infections. Overall, 68% of the isolates were classified as HA-MRSA and 32% as CA-MRSA. We identified differences in the patterns of virulence genes: 85% of HA-MRSA isolates possessed the enterotoxin gene cluster (egc), whereas 92% of CA-MRSA isolates possessed the lukF-PV/lukS-PV genes. Multivariate analysis showed an increased risk of mortality for seg (p = 0.001, odds ratio 4.73) and a protective effect for eta (p = 0.018, odds ratio 0.33). Conclusions: Our study confirms that three clones of MRSA predominantly circulate in Colombia: a Chilean clone, a pediatric clone that causes HA-MRSA infections, and a USA300-related clone (SCCmec IVc) in CA-MRSA infections, which differ in the content of clinically important virulence genes. This study confirms that PVL is not a determinant of severity or mortality in CA-MRSA infections. 2013 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved

Epidemiología molecular y caracterización de genes de virulencia de aislados de estafilococo aureus resistentes a la meticilina adquiridos en la comunidad y adquiridos en el hospital en Colombia

Objective: To determine the molecular epidemiology and presence of virulence genes in communityacquired (CA) and hospital-acquired (HA) methicillin-resistant Staphylococcus aureus (MRSA) isolates and their relationship to clinical outcomes. Methods: An observational and prospective study of infections caused by MRSA was conducted between June 2006 and December 2007 across seven hospitals in three Colombian cities. MRSA isolates were analyzed for SCCmec. Also, pulsed-field gel electrophoresis and multilocus sequence typing were performed and 25 virulence genes were identified. Results: Two hundred and seventy isolates were collected from 262 adult hospital patients with MRSA infections. Overall, 68% of the isolates were classified as HA-MRSA and 32% as CA-MRSA. We identified differences in the patterns of virulence genes: 85% of HA-MRSA isolates possessed the enterotoxin gene cluster (egc), whereas 92% of CA-MRSA isolates possessed the lukF-PV/lukS-PV genes. Multivariate analysis showed an increased risk of mortality for seg (p = 0.001, odds ratio 4.73) and a protective effect for eta (p = 0.018, odds ratio 0.33). Conclusions: Our study confirms that three clones of MRSA predominantly circulate in Colombia: a Chilean clone, a pediatric clone that causes HA-MRSA infections, and a USA300-related clone (SCCmec IVc) in CA-MRSA infections, which differ in the content of clinically important virulence genes. This study confirms that PVL is not a determinant of severity or mortality in CA-MRSA infections. 2013 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved

Efecto del roble (Quercus humboldtii) sobre los ensamblajes de plantas de los robledales de Colombia

Spa: Generalmente se asume que las especies dominantes de un ecosistema están bien adaptadas a su entorno y tienen altas capacidades competitivas. Por otra parte, la teoría neutral ha propuesto que por procesos de deriva ecológica, ciertas especies tienden a dominar en un área determinada por efecto solamente de su capacidad de dispersión. Quisimos evaluar estas hipótesis, enfocándonos en el Roble (Quercus humboldtii), el cual es un especie dominante en algunos bosques en los Andes colombianos y de la cual se reportan efectos alelopáticos sobre otras especies, aunque las evidencias empíricas son escazas. En este trabajo evaluamos el efecto de la presencia de roble sobre el crecimiento y la densidad de la madera, dos rasgos funcionales relacionados, de las especies que lo acompañan usando 20 parcelas donde se tienen datos de crecimiento de 114 especies incluyendo el roble. Una prueba de T-pareada indica que las tasas de crecimiento del 70% de las especies disminuye en presencia del roble (T=50.28, p<0.001). Luego, mediante un ANOVA encontramos que las especies con tasas de crecimiento no afectadas por el roble tienen una densidad de la madera significativamente mayor que las afectadas (F=5.21, p<0.05). Estos resultados sugieren que el Roble tiene ventajas competitivas sobre un gran número de especies y ayudan a entender su a dominancia en muchas regiones de los andes. Adicionalmente, ya que la especie está siendo utilizada ampliamente en programas de recuperación de áreas degradadas los resultados puede ser una guía para diseñar modelos de restauración más eficientes. Palabras clave: Quercus Humboldtii; Tasa de crecimiento; Robledal; Competencia