Gestational diabetes is associated with increased L-arginine transport and nitric oxide (NO) synthesis, and reduced adenosine transport in human umbilical vein endothelial cells (HUVEC). Adenosine increases endothelial L-arginine/NO pathway via A 2 purinoceptors in HUVEC from normal pregnancies. It is unknown whether the effect of gestational diabetes is associated with activation of these purinoceptors or altered expression of human cationic amino acid transporter 1 (hCAT-1) or human equilibrative nucleoside transporter 1 (hENT1), or endothelial NO synthase (eNOS) in HUVEC. Cells were isolated from normal or gestational diabetic pregnancies and cultured up to passage 2. Gestational diabetes increased hCAT-1 mRNA expression (2.4-fold) and activity, eNOS mRNA (2.3-fold), protein level (2.1-fold), and phosphorylation (3.8-fold), but reduced hENT1 mRNA expression (32%) and activity. Gestational diabetes increased extracellular adenosine (2.7 µM), and intracellular L-arginine (1.9 mM) and L-citrulline (0.

The existence of latitudinal gradients in species richness and their abundance is known for many free living organisms but few cases have been reported for parasitic diseases. In addition, asymmetries between the Northern and Southern Hemispheres in several characteristics may affect the distribution and diversity of species at all ecological levels. In this respect, we study the distribution of several genera of blood parasites infecting birds along a latitudinal gradient that includes the world's southernmost forests ecosystems. Birds were mist-netted and sampled for blood in localities across Chile ranging from 33 degrees S to 55 degrees S during the years 2003-06. Overall, 26 bird species were sampled and 27 parasite lineages were identified. The latter belonged to three genera: Plasmodium (8), Haemoproteus (8) and Leucocytozoon (11). We found a positive significant relationship between prevalence and latitude for Leucocytozoon lineages and a negative relationship for Haemoproteus, Plasmodium and mixed infections. However, we did not find a significant relationship between parasite diversity and latitude. We found 18 lineages infecting only one species of host, and 19 lineages appear in only one of the localities of sampling. This pattern implies that some parasite lineages may evolve in isolation in some species/localities. In addition, specificity at the host-family level was only found for Haemoproteus lineages infecting birds in the family Emberizidae. Individuals of the long distance migrant bird white-crested elaenia (Elaenia albiceps), were found infected by the same parasite lineages in localities separated by 20 degrees of latitude. Infections by these lineages were detected in other sedentary birds including juveniles and nestlings of different bird species. Therefore, long distance migrants are able to distort the presence of latitudinal gradients of diseases due to the potential role of migrants in spreading infections. Geographical gradients in prevalence of avian haematozoa differ between parasite genera and hemispheres, probably in relation to the existence of appropriate vector-parasite-host interactions

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Background: Environmental stressors increase the secretion of glucocorticoids that in turn can shorten telomeres via oxidative damage. Modification of telomere length, as a result of adversity faced early in life, can modify an individual's phenotype. Studies in captivity have suggested a relationship between glucocorticoids and telomere length in developing individuals, however less is known about that relationship in natural populations. Methods: In order to evaluate the effect of early environmental stressors on telomere length in natural populations, we compared baseline corticosterone (CORT) levels and telomere length in nestlings of the same age. We collected blood samples for hormone assay and telomere determination from two geographically distinct populations of the Thorn-tailed Rayadito (Aphrastura spinicauda) that differed in brood size; nestlings body mass and primary productivity. Within each population we used path analysis to evaluate the relationship between brood size, body mass, baseline CORT and telomere length. Results: Within each distinct population, path coefficients showed a positive relationship between brood size and baseline CORT and a strong and negative correlation between baseline CORT and telomere length. In general, nestlings that presented higher baseline CORT levels tended to present shorter telomeres. When comparing populations it was the low latitude population that presented higher levels of baseline CORT and shorter telomere length.

Abstract.It is well known that the risk of predation affects prey decision making. However, few studies have been concerned with the cues used by prey to assess this risk. Prey animals may use indirect environmental cues to assess predation hazard since direct evaluation may be dangerous. I studied the assessment of predation risk, manipulated via environmental illumination level, and the trade-off between foraging and predation hazard avoidance in the nocturnal rodent Phyllotis darwini (Rodentia: Cricetidae). In experimental arenas I simulated dark and full moon nights (which in nature correlate with low and high predation risk, respectively) and measured the immediate responses of animals to flyovers of a raptor model. Second, varying illumination only, I evaluated patch use, food consumption, central place foraging, and nocturnal variation of body weight. During flyover experiments, animals showed significantly more evasive reactions under full moon illumination than in moonless conditions. In the patch use experiments, rodents significantly increased their giving-up density and decreased their total food consumption under moonlight. On dark nights, rodents normally fed in the food patch, but when illumination was high they became central place foragers in large proportion. Moreover, the body weight of individuals decreased proportionately more during bright nights. These results strongly suggest that P. darwini uses the level of environmental illumination as a cue to the risk of being preyed upon and may sacrifice part of its energy return to avoid risky situations.

We present an analysis of behavioral flexibility in a day-active caviomorph rodent, the degu, Octodon degus, in response to temporal (daily and seasonal), spatial, and thermal heterogeneity of its environment. We quantified activity and foraging behavior in a population, together with thermal conditions, in an open habitat in the seasonally hot and arid matorral of central Chile. Summer activity was bimodal, with a gap of more than 8 h between the morning bout of 2.5 h of intensive foraging and the afternoon bout of 2 h. More than half of the 4.5 h of summer activity occurred in the shade of early morning or late afternoon when the sun was below the local skyline. Autumn and spring activity were also bimodal, but with greater proportions of activity under direct solar radiation, and with a shorter midday gap between the two major bouts. Winter activity was unimodal and all occurred under direct solar radiation. In summer, autumn, and spring the activity of degus was curtailed as our index of operative temperature, T e , moved above 40 ºC. We used a single measurement of T e (measured in a thermal mannequin representing degu size, shape and surface properties) as an index of the interactive effects of solar radiation and convection on body temperature. At the winter solstice (June), when degus remained fully exposed to solar radiation throughout the day, T e generally remained below 30 ºC. Flexibility in the timing of surface activity allows degus to maintain thermal homeostasis and energy balance throughout the year. Degus shift the times of daily onset and end of activity and the number of major bouts (unimodal or bimodal) over the course of the year. They remain active on the surface under a much narrower range or "window" of thermal conditions than those that occur over the entire broad range of the day and year.Key words: Chile, foraging, Octodon degus, seasonality, thermal ecology. RESUMENPresentamos un análisis de la flexibilidad conductual en la actividad diaria del degu (Octodon degus), un roedor caviomorfo, en respuesta a la heterogeneidad del ambiente temporal (diario y estacional), espacial y térmico. Junto con las condiciones térmicas, cuantificamos la conducta de actividad y forrajeo en una población que vive en un hábitat abierto en el matorral árido y estacional de Chile central. La actividad de verano fue bimodal, con 2,5 h de actividad de forrajeo intenso durante la mañana y con 2 h durante la tarde. No hubo actividad por mas de 8 h entre ambos eventos. Más de la mitad de las 4,5 h diarias de actividad de la mañana y de la tarde ocurrieron en la sombra, cuando el sol se encuentra bajo la línea local del cielo. La actividad durante el otoño y la primavera también fue bimodal pero con una mayor proporción de actividad bajo radiación solar directa y con un período de inactividad menor entre los dos eventos principales. La actividad de invierno fue unimodal y bajo radiación solar directa. En verano, otoño y primavera la actividad estuvo sesgada cuando nuestro índice de temperatura operativa,...

We present evidence of differential maternal allocation to eggs in response to manipulated male attractiveness in the migratory pied flycatcher (Ficedula hypoleuca). We manipulated the size of a male secondary sexual trait, the white forehead patch, right after male arrival to the breeding area and before female arrival. Patch size was (1) enlarged to the maximum observed in the population, (2) reduced by 40% or (3) kept constant by painting with indelible felt markers over the natural feather patch. Male behaviour was affected by the experimental manipulation, as individuals with enlarged patches performed more approaches to the nestbox in response to song playback during the territory occupation and nest-site presentation phases. Females paired with males with reduced forehead patches laid significantly smaller eggs than those paired with males in the control and enlargedpatch treatments. Laying date and clutch size did not differ among the experimental groups. We discuss that manipulations of ornaments designed to study differential allocation at laying should reduce as well as enlarge their expression.

We conducted a study of the breeding biology of the Thorn-tailed Rayadito (Aphrastura spinicauda) in secondary forests on the continental island of Chiloé (42° S), southern Chile. Rayaditos are small insectivorous furnariids inhabiting the south-temperate forests of Chile and Argentina. We followed the reproduction of rayadito pairs breeding in nest-boxes. Rayaditos build their nests mainly of rhizomes and stems of epiphytic vines, grasses, and hairs during periods of at least a week, and show a marked population asynchrony in laying dates of more than two months (October–December). Rayaditos lay clutches of 3–6 eggs with a mode of 4 and laying occurs on alternate days. Eggs are 50% larger and hatchlings are 30% larger than expected from allometric equations. Most broods hatch synchronously. Nestling growth curves adjust well to logistic functions and at 2 weeks nestlings attain masses similar to asymptotic values. Nestling growth, which occurs over 3 weeks, is 27% slower than expected from allometry. Fledglings attain adult size with respect to tarsus length, but have less developed plumage and higher body mass than adults. Rayaditos exhibit clutch and brood reduction, suggesting possible food limitation. The protracted breeding periods may preclude second breeding attempts for most pairs in Chiloé. There is evidence for declines in parental quality with season. The low seasonal fecundity, large eggs, and prolonged dependence periods of a truly south-temperate species like the Thorn-tailed Rayadito reflect a ‘slow’ life history similar to that of tropical passerines. Biología Reproductiva de Aphrastura spinicauda (Furnariidae) en Bosques Lluviosos Templados Meridionales de Chile Resumen. Realizamos un estudio de la biología reproductiva del Rayadito Aphrastura spinicauda en bosques secundarios de la isla continental de Chiloé (42° S), sur de Chile. Este pequeño furnárido insectívoro habita los bosques templados meridionales de Chile y Argentina. Seguimos las actividades reproductivas de parejas de rayaditos que utilizaron cajas artificiales para nidificar. Los rayaditos construyen sus nidos utilizando rizomas, hierbas y pelo durante períodos de al menos una semana, y muestran una marcada asincronía a nivel de población de más de dos meses (octubre a diciembre) en el inicio de la puesta. Las puestas incluyen de 3 a 6 huevos, con un tamaño modal de 4 huevos, los cuales son puestos en días alternos. Los huevos son 50% más grandes y los polluelos recién eclosionados 30% más grandes de lo esperado según ecuaciones alométricas. La mayoría de las nidadas eclosionan sincrónicamente. Las curvas de crecimiento se ajustan bien a funciones logísticas y el peso alcanza valores asintóticos a las dos semanas. El crecimiento de los polluelos, que ocurre durante un período de permanencia en el nido de tres semanas, es un 27% más lento de lo esperado por alometría. Los volantones alcanzan el tamaño adulto con respecto a la longitud de tarso, pero presentan un plumaje menos desarrollado y un mayor peso que los adultos. Esta especie presenta casos de reducción de la puesta o de la nidada, lo que sugiere posibles limitaciones en la disponibilidad de alimentos. Los prolongados períodos de reproducción pueden impedir el inicio de segundas puestas en Chiloé. Hay evidencia de disminuciones estacionales en la calidad parental. La baja fecundidad anual, el gran tamaño de los huevos y el prolongado periodo de crecimiento del Rayadito refleja una historia de vida ‘lenta’ similar a la de paseriformes tropicales.