The species Nierembergia linariifolia var. linariifolia has been historically incriminated as toxic for animals in northwestern Argentina. A dose of 10 g of ground dry matter / kg of live weight was administered to three adult goats by the use of a nasogastric tube. Another three animals remained as "control group", and receiving alfalfa hay. The goats that received the plant presented clinical signs of abdominal colic between 7 and 45 hours post-administration. None of the animals died and all recovered fully within 72 hours of initiation of the test. Nierembergia linariifolia var. linariaefolia showed to have toxic effects at the gastrointestinal level at the dose administered, although no severe damage was observed.

Nierembergia linariifolia var. linariifolia ha sido sospechada históricamente como planta tóxica en algunas regiones del noroeste de Argentina. Se administró una dosis de 10 g de materia seca de planta molida/kg de peso, a tres cabras adultas mediante el empleo de sonda nasogástrica. Otros tres animales permanecieron como grupo control y recibieron heno de alfalfa. Las cabras que recibieron la planta, presentaron signos clínicos de cólico abdominal entre las 7 y 45 horas post-administración. Ninguno de los animales murió y todos se recuperaron totalmente a las 72 horas de iniciado el ensayo. Nierembergia linariifolia var. linariaefolia demostró tener efectos tóxicos a nivel gastrointestinal a la dosis administrada, aunque no se observaron daños más severos.

A post-Cretaceous sedimentary rocks outcrop has been found in Bahía Crossley (54°48'16"S and 64°41'3.8"W) in the north-western part of the island. The lower contact with the folded strata of the Beauvoir Formation (Late Jurassic-Early Cretaceous) is represented by an angular unconformity. These new deposit could be correlated with the Tertiary continental strata of the Punta Cactus and Bahía Sloggett Formations, Bahía Sloggett (54°59'34"S and 66°19'57"W), Tierra del Fuego. There is not enough available information yet to provide a precise age of these new outcrops, although they are younger than the folding of the Beauvoir Formation (Late Cretaceous). We present the principal characteristics of these beds and the implications of this discovery for the regional geological history.

Un afloramiento de rocas sedimentarias postcretácicas, desconocido hasta el momento, ha sido hallado en bahía Crossley (54°48'16"S y 64°41'3,8"O) en la porción noroeste de la isla de los Estados. El mismo se dispone en forma horizontal a subhorizontal sobre los estratos plegados de la Formación Beauvoir (Jurásico Superior-Cretácico Inferior) por medio de una discordancia angular. No se conocen datos ni menciones previas sobre esta secuencia en la literatura. Una posible correlación podría establecerse con los estratos del Terciario continental de las Formaciones Punta Cactus y Sloggett, aflorantes en bahía Sloggett, Tierra del Fuego (54°59'34"S y 66°19'3";O). Aún no se cuenta con información fehaciente que precise la edad de estos nuevos depósitos, aunque son posteriores al plegamiento de la Formación Beauvoir (Cretácico Superior). Se presentan las características principales de estas capas y las implicancias del hallazgo para la historia geológica de la región.

The effect of three different lipid sources (soybean oil, chicken oil or bovine fat) on the abdominal fat fatty acid composition in 50 day-old broiler chickens was evaluated. A completely randomized design was used, with 4 treatments, 8 repetitions and 40 Arbor Acres broiler chicks of each sex. The four treatments were isocaloric and isoproteic with the following characteristics: T1 Control (Soybean-corn); T2 Control + 3% soybean oil; T3 Control + 3% chicken oil; and T4 Control + 3% bovine fat. The lipids from the diets had significantly statistical effects (p<0,05) on the fatty acid composition of broiler abdominal fat. Multivariate techniques also showed differences in fatty acid composition within treatments due to sex. The studied dietary lipids affected the polyunsaturated/saturated fatty acid ratio (P/S) but had only small effects on the n-6: n-3 fatty acid ratio.

The aim of this work was to evaluate sex effect on behavior of two commercial broilers lines. Productive parameters, carcass composition and yield, amount and quality of fat deposited in the meat and skin and total body fat were studied. A completely randomized design with four treatments (MR-Male Ross, HR-Female Ross, MAF-Male Avian Farm and HAF-Female Avian Farm) and eight repetitions of 40 chickens was used. Animals received water and food ad libitum. After 50 days, two birds (a male and a female) per repetition were chosen at random and slaughtered for carcass evaluation. Samples of breast, leg, skin and abdominal fats were analyzed to determine the percentage of intramuscular fat, total cholesterol and fatty acid composition. The Ross line showed higher final weight and weight gain, better intake and feed conversion rate. Also, it was observed that females of both lines had similar results in relation to these parameters. Better yield of breast with bone was found in Ross males and females. In relation to legs and thigh, Ross males showed better results and no differences were observed among females of both lines. Males deposited less fat than females. Finally, differences in percentage of intramuscular fat, content of cholesterol in breast with skin, leg with skin and skin, percentage of saturated, mono and polyunsaturated fatty acids were observed between sex and lines.

It has been propoosed that one of the functions of the enzyme phosphoenolpyruvate carboxylase (PEPCase) in the roots of white lupines consists in providing the carbon required to support the significant quantity of citrate that is excreted by P-starved plants. To demonstrate that citrate excretion by roots is an event more sensitive to P concentration than PEPCase, the activity of the enzyme extracted from roots of white lupines growing in soil as well as its activity and citrate release in plants growing in a nutrient solution were measured. PEPCase activity of plants growing in soil at five P treatments (with P added to obtain shoot P ranging from deficient to adequate) varied from 0.22 to 0.18 m mole NADH mg protein-1 min-1 for a shoot P of 0.14 to 0.19%, respectively. In a broad range of P concentrations in nutrient solutions (with P added to obtain shoot P ranging from deficient to near toxicity), the enzyme activity and citrate release were reduced to almost undetectable levels when shoot P was increased to 0.7 and 0.5%, respectively. The results indicate that in vitro PEPCase activity does not significantly change with the range of shoot P from deficient to adequate, and suggest that the mechanism associated with citrate excretion might be impaired at P concentrations lower than those required to inhibit PEPCase activity.

Se ha propuesto que una de las funciones de la enzima fosfoenolpiruvato carboxilasa (PEPCasa) de raíces de lupino blanco (Lupinus albus) consiste en proveer del carbono requerido para soportar la significativa cantidad de citrato que es exudado por plantas sometidas a deficiencias de P. Con el propósito de demostrar que la excreción de citrato es un evento más sensible a la concentración de P que la PEPCasa, se cuantificó la actividad de la enzima en lupino blanco mantenido en suelo, así como su actividad y exudación de citrato en plantas mantenidas en solución nutritiva. La actividad PEPCasa de plantas mantenidas en suelo (con P agregado para obtener concentraciones de P en la biomasa aérea fluctuante entre deficiente y adecuado) varió entre 0,22 y 0,18 m moles NADH mg proteína-1 min-1, para concentraciones de P en la biomasa aérea de 0,14 y 0,19%, respectivamente. En un rango más amplio de concentraciones de P en solución nutritiva (con P agregado para obtener concentraciones de P en la biomasa aérea entre deficiente y cercano a toxicidad), la actividad de la enzima y la exudación de citrato se redujeron a niveles casi no detectables, cuando las concentraciones de P en la biomasa aérea se elevaron a 0,7 y 0,5%, respectivamente. Estos resultados indican que la actividad PEPCasa in vitro no se alteró significativamente en plantas mantenidas con concentraciones de P en la biomasa aérea entre deficiente a adecuado, y sugieren que el mecanismo asociado con la excreción de citrato sería inhibido por concentraciones de P inferiores a aquellas requeridas para inhibir la actividad de la enzima PEPCasa.