Giorgio Castellaro

Fertility in a high-altitude environment is compromised by luteal dysfunction: the relative roles of hypoxia and oxidative stress

BackgroundAt high altitudes, hypoxia, oxidative stress or both compromise sheep fertility. In the present work, we tested the relative effect of short- or long-term exposure to high altitude hypobaric hypoxia and oxidative stress on corpora luteal structure and function.MethodsThe growth dynamics of the corpora lutea during the estrous cycle were studied daily by ultrasonography in cycling sheep that were either native or naïve to high-altitude conditions and that were supplemented or not supplemented with antioxidant vitamins. Arterial and venous blood samples were simultaneously drawn for determination of gases and oxidative stress biomarkers and progesterone measurement. On day five after ovulation in the next cycle, the ovaries were removed for immunodetection of luteal HIF-1alpha and VEGF and IGF-I and to detect IGF-II gene expression.ResultsThe results showed that both short- and long-term exposure to high-altitude conditions decreased luteal growth and IGF-I and IGF-II gene expression but increased HIF-1 alpha and VEGF immunoexpression. The level of plasma progesterone was also increased at a high altitude, although an association with increased corpus luteum vascularization was only found in sheep native to a high-altitude location. Administration of antioxidant vitamins resulted in a limited effect, which was restricted to decreased expression of oxidative stress biomarkers and luteal HIF-1alpha and VEGF immunoexpression.ConclusionsExposure of the sheep to high-altitude hypobaric hypoxia for short or long time periods affects the development and function of the corpus luteum. Moreover, the observed association of oxidative stress with hypoxia and the absence of any significant effect of antioxidant vitamins on most anatomical and functional corpus luteum traits suggests that the effects of high altitude on this ovarian structure are mainly mediated by hypoxia. Thus, these findings may help explain the decrease in sheep fertility at a high altitude.

Disturbances in Maternal Steroidogenesis and Appearance of Intrauterine Growth Retardation at High-Altitude Environments Are Established from Early Pregnancy. Effects of Treatment with Antioxidant Vitamins.

Pregnancies at high-altitudes are influenced by hypoxia and oxidative stress and frequently affected by IUGR. However, a common thought is that early pregnant women visiting altitude have no major complications for gestation development, since IUGR is developed during the second half of pregnancy. Thus, using a well-characterized sheep-model, we aimed to determine whether long- and/or short-term exposure to high-altitude may affect maternal steroidogenesis and therefore embryo-fetal growth from conception. The second aim was to differentiate the relative role of hypoxia and oxidative stress by assessing the effects of supplementation with antioxidant agents during this early-pregnancy stage, which were previously found to be useful to prevent IUGR. The results indicate that both long- and short-term exposure to high-altitude causes disturbances in maternal ovarian steroidogenesis and negatively affects embryo-fetal growth already during the very early stages of gestation, with the consequences being even worsened in newcomers to high-altitude. The supply of antioxidant during this period only showed discrete effects for preventing IUGR. In conclusion, the present study gives a warning for clinicians about the risks for early-pregnant women when visiting high-altitude regions and suggests the need for further studies on the effects of the length of exposure and on the interaction of the exposure with the pregnancy stage.

Characterization of genetic coefficients of durum wheat (Triticum turgidumL. ssp. durum)'Llareta-INIA' and 'Corcolén-INIA'

The genetic coefficients, representative of a crop, are necessary to use growth models; in many cases the range of the species is known, but there are no specific values for varieties. Durum wheat ( Triticum turgidum L. ssp. durum ) ‘Llareta- INIA’ and ‘Corcolen-INIA’ were sown under irrigation in the experiment station Antumapu of the Universidad de Chile on 29 June 2007, 19 May 2009, and 15 June 2010 in order to determinate four genetic coefficients: developmental thermal time, phyllochron (PHLN), extinction coefficient (k), and radiation use efficiency (RUE), and to evaluate the performance of these coefficients. Thermal times to anthesis and from anthesis to physiological maturity were 652 and 541° C d, respectively. Two PHLN values were found, 46.6° C d leaf-1 from emergence to fifth leaf and 102.9 ° C d leaf-1 from fifth to eighth leaf. In both cases neither variety nor sowing date was significant. The value of k did not vary among sowing dates for ‘Llareta-INIA’ and was not significantly different from that of ‘Corcolen-INIA’ for normal planting date, due to which a single fit for the two varieties was adjusted, obtaining a value of 0.46. However, ‘Corcolen-INIA’ had a lower value of k for later sowing dates. RUE did not vary between varieties or sowing dates; its estimated value was 2.83 g MJ-1. The evaluation of the coefficients obtained showed coherent results, thus they can be used in model simulations.

Aplicación de un Algoritmo de Split-Window para la Estimación de la Temeratura de la Superficie Terrestre desde Datos AVHRR-NOAA

Estimaciones de temperatura de la superficie terrestre, en dias parciales a completamente despejados, fueron realizadas a partir de los datos proporcionados por el sensor Advanced Very High Resolution Radiometer (AVHRR), a bordo de la serie de satelites de la National Oceanic and Atmospheric Administration (NOAA) por aplicacion de un algoritmo basado en el metodo de Split-Window. El algoritmo utilizado supone correcciones por emisividad y contenido de vapor de agua atmosferico, y fue validado con mediciones de temperatura de la superficie terrestre realizadas en terreno. Para esto, un data logger LI-1000 se instalo en la Estacion Agrometeorologica dependiente del Instituto de Investigaciones Agropecuarias, Centro Regional de Investigacion Carillanca, Region de la Araucania (38°41?lat. S; 72°25?long. O; 200 m.s.n.m). Las mediciones de temperatura se realizaron a intervalos temporales de una hora. Los resultados obtenidos muestran que la aplicacion del algoritmo permite obtener la temperatura de la superficie terrestre con un alto grado de confianza, obteniendose un error cuadrado medio de la prediccion (RMSE) inferior al 1%.

Botanical Composition of Alpaca (Lama pacos Linn.) Diet in a Central Mediterranean Range of Chile

CHILEAN JOURNAL OF AGRICULTURAL RESEARCH 68:136-145 (APRIL-JUNE 2008) A B S T R A C T The re-introduction of domestic South American camelids (alpacas and llamas) in the central zone of Chile makes it necessary to study their behaviour and adaptability. Since it is fundamental to characterize the camelid’s diet, the present work had as an objective the determination of the plant species selected by the alpacas (Lama pacos Linn.) in different phenological stages (vegetative, reproductive and dry season). The study was carried out over three years in a paddock of 2.5 ha of sparse shrubland dominated by Acacia caven (Mol.) Mol. and annual species in the herbaceous stratum, which were continually grazed by five male alpacas. The botanical composition and the forage dry matter available for grazing in the pasture was evaluated. Botanical composition of diets was estimated with the microhistological technique, using dung samples collected directly from the rectum. During the vegetative season, the most consumed plant species were annual and perennial grasses. In the reproductive season, the most important components of the diet were woody plant species, annual grasses and forbs. In the dry season, the diet was composed of a high percentage of woody plant species.

A simple method for estimating suitable territory for bioenergy species in Chile

In the past 20 years, different areas of research concerning native and exotic species, herbaceous crops and forest plantations have been oriented toward satisfying domestic, industrial and transportation energy requirements. Because bioenergy species constitute an important resource, it would be strategic for a country to have a method for identifying areas suitable for their cultivation to properly incorporate the establishment of energy crops into land use planning. In this study, we sought to define the suitable territories for 16 bioenergy species and their energy potential based on their soil and climate requirements in Central and Southern Chile. We used an adapted version of the FAO EcoCrop database implemented through DIVA-GIS software to predict the crop suitability of different geographical areas, and our results indicate that this method is a simple way to identify land suitable for the establishment of bioenergy species, which is information that can be used in land use planning. Furthermore, spatially explicit regression and ordinary kriging proved to be satisfactory tools for interpolating data from weather station networks through the generation of continuous climatic information grids. Land suitability is presented at a scale of 1:1,000,000 in a continuous digital format expressed in probabilistic terms. En estos ultimos 20 anos diversas lineas de investigacion en especies nativas y exoticas, cultivos herbaceos y plantaciones forestales se han orientado al desarrollo de aplicaciones energeticas domesticas, industriales y para el transporte. Como son un recurso importante, es estrategico contar con un metodo que permita identificar en el territorio nacional las areas con aptitud para el cultivo de estas especies, con el objetivo de realizar una planificacion territorial adecuada para el establecimiento de las plantaciones bioenergeticas. En este estudio se presenta un metodo simple para definir la idoneidad territorial de 16 especies con potencial energetico (El Bassam, 2010) en el Centro y Sur de Chile, en base a sus requerimientos de suelo y clima. Se utilizo una adaptacion del metodo EcoCrop implementado en el software DIVA-GIS para predecir la idoneidad de los cultivos en dicha zona geografica. Los resultados muestran que el metodo propuesto representa una forma sencilla de estimar las zonas del territorio con idoneidad adecuada para establecer plantaciones bioenergeticas especificas, informacion que puede ser utilizada para la toma de decisiones en la planificacion del territorio. La regresion espacialmente explicita y el kriging ordinario mostraron ser una herramienta satisfactoria de interpolacion de los datos obtenidos de redes de estaciones climaticas para la generacion de rejillas continuas de datos climaticos. La idoneidad territorial se presenta en un formato digital continuo expresado en terminos probabilisticos a una escala 1:1.000.000.