No abstract

: Essential oils as natural sanitizing agents were sprayed on Swiss chard leaves produced by organic methods. Samples were stored at 0 and 5°C and 97% to 98% relative humidity. Microbial populations, peroxidase activity, and sensory attributes were monitored during storage. No significant differences were observed between treated and control samples stored at 0°C. However, samples treated with the essential oils of eucalyptus, tea tree, and clove and stored at 5°C presented microbial counts significantly lower than those of control samples. The essential oils of eucalyptus, tea tree, lemon, rosemary, and clove presented peroxidase activity inhibition that, in the case of eucalyptus, increased to 65% during storage. Although some of the essential oils did appear to reduce microbial counts and peroxidase activity compared with controls, they were not effective in extending the shelflife of the Swiss chard leaves from a sensory point of view.

INTRODUCCIÓN Las enfermedades cardiovasculares constituyen un problema de salud pública por su alta prevalencia y por ser la principal causa de muerte de la población adulta en la mayoría de los países (1). Según diversos estudios, la población de adultos jóvenes parece encaminarse hacia la adopción de conductas de riesgo y estilos de vida poco saludables. Algunos autores lo atribuyen a las débiles conexiones entre la población universitaria con la redes de apoyo; como la familia y los centros educacionales (2,3). Los estudiantes son sometidos a condiciones particulares al ingresar al sistema universitario. El ambiente académico puede producir cambios en sus estilos de vida, con implicaciones positivas y negativas. Se encuentran en una etapa crítica para el desarrollo de sus hábitos alimentarios, caracterizados por presentar poco tiempo para comer, saltarse comidas frecuentemente, comer entre horas, alto consumo de comida rápida, entre otros (4,5). Sumado a esto, presentan una disminución de la práctica de actividad física por el auge que han tenido

(Rev Med Chile 2011; 139: 1573-1580.

South America was invaded by slider turtles (Trachemys spp.) twice, with one immigration wave estimated to have reached South America 8.6-7.1 million years ago (mya) and a second wave, 2.5-2.2 mya. The two widely disjunct South American subspecies of Trachemys dorbigni (northeastern and southern Brazil, R ıo de la Plata region of Argentina and Uruguay) are derived from the first dispersal pulse, while the two South American subspecies of Trachemys venusta (Colombia, Venezuela) originated from the second immigration event. We describe a new species of slider turtle from the lower Atrato river basin of Antioquia and Choc o departments, northwestern Colombia. This new species, the Atrato slider (Trachemys medemi n. sp.), is the first representative of the older immigration wave inhabiting northern South America. Using phylogenetic analyses of 3,242 bp of mitochondrial and 3,396 bp of nuclear DNA, we show that T. medemi is more closely related to T. dorbigni than to the geographically neighboring subspecies of Trachemys grayi and T. venusta from Central America and northern South America. The two subspecies of T. dorbigni are separated from the Atrato slider by the Andes and the Amazon Basin, and occur approximately 4,600 km and 3,700 km distant from T. medemi. According to molecular clock calculations, T. medemi diverged from the last common ancestor of the two subspecies of T. dorbigni during the Pliocene (4.1-2.8 mya), with T. dorbigni diversifying later (2.3-1.9 mya) in eastern South America beyond the Amazon basin. The divergence of the T. dorbigni subspecies overlaps with the estimated arrival of T. venusta in South America (2.5-2.2 mya). This time is characterized by massive climatic and environmental fluctuations with intermittent dispersal corridors in South America. According to their distribution, it seems likely that the ancestors of the extant subspecies of T. dorbigni dispersed along the eastern corridor, leaving a relict population northwest of the Andes with T. medemi.The distribution range of T. medemi is surrounded by taxa derived from the second southern range expansion of slider turtles, so that it can be concluded that T. venusta circumvented the habitats occupied by the ancestors of the Atrato slider when entering South America.