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Circadian Rhythm of Salivary Cortisol in Asian Elephants (Elephas maximus): A Factor to Consider During Welfare Assessment

Elevated glucocorticoid levels during an extended time period might be a stress indicator in nonhuman animals. Therefore, knowledge of the circadian pattern of cortisol secretion is very important to correctly interpret data obtained for welfare assessment of animals in captivity through salivary cortisol. In order to define the circadian rhythm of salivary cortisol secretion in the Asian elephant (Elephas maximus), morning and evening saliva samples of 3 Asian elephants were collected and analyzed by radioimmunoassay. Significantly higher salivary cortisol concentrations were found in the morning than in the evening in all individuals. These results show that salivary cortisol of Asian elephants follows a diurnal pattern of secretion, which could be taken into account when using this methodology to assess welfare in captive Asian elephants.

Seasonal pattern of salivary cortisol secretion in the greater one-horned rhino (Rhinoceros unicornis)

The Indian rhinoceros or greater one-horned rhino (Rhinoceros unicornis) is listed as vulnerable by the IUCN Red List of Threatened Species and, therefore, captive individuals have been subject to the European Endangered Species Programme since 1990. Enhancement of welfare is key in ensuring the breeding success of this species in captivity. Salivary cortisol has been recently used to assess welfare of captive and free-ranging animals. Nevertheless, rhythms of cortisol secretion may fluctuate throughout the year and therefore, knowledge of the circannual pattern of cortisol secretion is essential to evaluate the physiological significance of seasonal variations of cortisol levels as an indicator of stress in animals. Here, we analyse monthly differences in cortisol secretion in two Indian rhinoceros. Saliva samples of two rhinoceros were collected and analysed by radioimmunoassay for the period of one year to determine cortisol concentrations. We found a seasonal pattern of salivary cortisol secretion. The highest cortisol concentrations were found in August and decreased until reaching a nadir in January. Cortisol concentrations in these two animals showed a correlation with temperature and visitor numbers but it is not possible to draw conclusions from this study as to whether the variation in cortisol was due to these or other factors.

La integración de los trabajos prácticos en la enseñanza de la química como investigación dirigida

A pesar de la importancia de las practicas de laboratorio para aprender tanto ciencias como naturaleza de las ciencias, las practicas habituales suelen transmitir a los estudiantes una vision ateorica y empirista de la ciencia y consistir en un laboratorio tipo receta, como secuencias de instrucciones con serias carencias desde el punto de vista de la epistemologia cientifica. Mostramos que estas deficiencias pueden superarse desde los modelos de ensenanza por investigacion o indagacion, concretando en el modelo de ensenanza por investigacion en torno a problemas fundamentales, en el que el trabajo practico se integra dentro de la estructura de los temas de un modo coherente con la introduccion de conceptos y modelos y la resolucion de problemas. A titulo de ejemplo, transformamos una practica habitual sobre velocidad de reaccion (tiosulfato de sodio con acido clorhidrico) en una secuencia problematizada de actividades, incluyendo comentarios didacticos detallados para cada una de las actividades de la secuencia.