Behavioral discrimination between monogyne and polygyne red fire ants (Hymenoptera: Formicidae) in their native range

Nestmate recognition among social insects is presumed to restrict non-nestmates from exploiting nest resources. Here, we developed aggression bioassays to assess the discrimination behaviors of both polygynous and monogynous forms of the red fire ant, Solenopsis invicta Buren, during symmetrical interactions in neutral arenas. Workers from polygyne colonies exhibited risk avoidance behaviors; that is, defensive postures or the avoidance of direct contact during interactions. Workers from monogyne colonies always exhibited aggressive behaviors in the form of physical or chemical attacks. In interactions between both, monogyne workers usually started the aggression by surrounding and biting the polygyne ants. Polygyne S. invicta workers also distinguished nestmates from foreigners, but their response was not as aggressive as that of monogynes. The proposed ethogram that we constructed identified monogyne and polygyne forms of S. invicta colonies in concordance with current measures, including number of queens, and expression of the Gp-9 gene.Fil: Chirino, Monica Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Centro de Estudios e Investigación; ArgentinaFil: Gilbert, Lawrence E.. University of Texas at Austin; Estados UnidosFil: Folgarait, Patricia Julia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Centro de Estudios e Investigación; Argentin

Pseudacteon tricuspis: Its behavior and development according to the social form of its host and the role of interference competition among females

We studied how the behavior and performance of Pseudacteon tricuspis Borgmeier varies with the social form of its host Solenopsis invicta Buren, in its native range in Argentina where monogyne colonies are more abundant than polygynes (≈75 vs. 25%). Female, P. tricuspis took 44% less time (50 vs. 89 s) to attack monogyne than polygyne ants, but oviposition attempts were similar (23 vs. 18 attacks). The presence of the parasitoid affected the average size of foragers on the trail, with the proportion of minor workers increasing on both social forms. In the laboratory, P. tricuspis selected similar host sizes, although pupal survival was 25% higher on monogynes than on polygynes. Developmental times of both genders were similar (3335 d), although larger females emerged from bigger hosts. The sex ratio of P. tricuspis was more male biased when exploiting polygyne ants. Intraspecific competition significantly affected parasitoid reproductive success, being significantly higher for a solitary female than when three females were present, although the size of workers selected did not vary. The male:female ratio also changed, being 1:1 without competition but 2:1 with competition. We demonstrated for the first time the consequences of interference competition among P. tricuspis females, a common behavior observed in others parasitoids. We discuss why P. tricuspis sex ratios are always biased toward males in both social forms and suggest that similar studies of interference competition within and between already naturalized Pseudacteon species in the United States could help predict establishment patterns.Fil: Chirino, Monica Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Centro de Estudios e Investigación; ArgentinaFil: Folgarait, Patricia Julia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Centro de Estudios e Investigación; ArgentinaFil: Gilbert, Lawrence E.. University of Texas at Austin; Estados Unido

Características de tres pastizales bajos con distinto periodo de descanso

In an upland region with short grassland in the Dpto Loventué- La Pampa (Lat-.36°50' S Long.65°18' W) we compared three areas-. Two of them were exclosures of 28 and 14 years; the third had a rest of twelve months every other year. The three communities were similar in floristic composition but different in the values of abundance-cover of their principal species. Vegetation cover had a maximum in the exclosures and a minimum in the area that had a rest of twelve months every other year. In the three areas the frequency of dominants and codominants species ranged among 90-100%. Standing crop reached 320 gMS/m2 in the oldest exclosure and 150 gMS/m2 in the area with a rest of twelve months every other year. Flower stalk numbers, culm lenght and crown diameter were great in the 14 years exclosure·.koeleria permollis a decreaser palatable specie was codominant only in the 28 years exclosure. Poa ligularis another decreaser desiderable specie codominated in the 14 years exclosure. In the area with a rest of twelve months every other year was dominant Piptochaetium.En una región con pastizal bajo del departamento, La Pampa (lat·.36°50' S Long'. 65°18' W) se analizaron las diferencias entre tres áreas. Dos de ellas eran clausuras de 28 y 14 años. La tercera tuvo en los últimos años un descanso de doce meses, año por medio. Las tres áreas son similares en composición florística, pero difieren en los valores de abundancia-cobertura de sus especies principales. La cobertura de la vegetación tuvo un máximo en las dos clausuras y un mínimo en el área con descanso de doce meses, año por medio. La frecuencia de las especies dominantes y codominantes vario del 90 al 100%. La fitomasa aérea alcanzó a 320 gMS/m2 en el área no pastoreada durante 28 años y de150 gMS/m2 en el área con un descanso anual, año por medio. Los valores de altura de cañas, altura verde y diámetro de corona fueron mayores en la clausura de 14 años. Koeleria permollis una especie decreciente codominó solamente en la clausura de 28 años. Poa ligularis otra especie decreciente, deseable, codominó en la clausura de 14 años y Piptochaetium napostaense domino en el área con un descanso de doce meses, año por medio

Presence of Clostridium difficile in pig faecal samples and wild animal species associated with pig farms

Aims: to determine the presence of Clostridium difficile on fattening pig farms in north-eastern Spain. Methods and results: Twenty-seven farms were sampled. Pools of pig faecal samples (n = 210), samples of intestinal content from common farm pest species (n = 95) and environment-related samples (n = 93) were collected. Isolates were tested for toxin genes of C. difficile, and typed by PCR-ribotyping and toxinotyping. The minimal inhibitory concentrations of six antimicrobial agents were determined using Etest. Thirty-four isolates were obtained from 12 farms, and 30 (88·2%) had toxin genes. Seven ribotypes were identified. Ribotype 078 and its variant 126 were predominant (52·9%). The same ribotypes were isolated from different animal species on the same farm. None of the isolates were resistant to metronidazole or vancomycin. Conclusions: Clostridium difficile was common within the pig farm environment. Most of the positive samples came from pest species or were pest-related environmental samples. Significance and Impact of the Study: Pest species were colonized with toxigenic and antimicrobial-resistant C. difficile strains of the same ribotypes that are found in humans and pigs. Rodents and pigeons may transmit toxigenic and antimicrobial-resistant C. difficile strains that are of the same ribotypes as those occuring in humans

Estados de condición del sitio pastizal de gramíneas bajas de planicie presentes en el departamento Loventué La Pampa

It has been evaluating range condition in twenty areas of shortgrasslands in Loventué - La Pampa. The state Condition's identification was realized with the standing - crop's dates. Frequency, density, cover and height of principal’s species were taken. The following indices were used to classified the grassland's Condition: Very Good; Good, Fair, Poor and Very Poor.Se evaluó la condición de pastura en 20 áreas de pastizal de planicie en el Departamento Loventué, La Pampa. La identificación del estado de condición se realizó en función del peso de las especies por unidad de muestreo. Se hicieron además determinaciones de frecuencia, densidad, cobertura y altura de las especies más importantes. Para la determinación de la condición de las áreas, fueron usados los siguientes índices: Muy buena. Buena, Regular, Mala y Muy Mala

Determinación de proteína bruta de algunas especies forrajeras de La Pampa

This work took place in three different grasslands in the Province of La Pampa. The first, located in LAS MERCEDES farm, departament of TOAY, with predominane of Digitaria californica. This warm season species reached 14,4% of crude protein (CP) at the beginning of growing season. LA BAYA VIEJA farm was the second place under study, with predominance of winter season species such as Poa ligularis, Piptochaetium napostaense on which 8,5% and 12,4% of CP were obtained respectively in the grow out after cutting. The third place was LOS GUADALES farm, depatament of CALEU CALEU with predominance, of Pappophorum caespitosum during summer and Medicago minima and Erodium cicutarium in winter, wich resulted 9,8%, 24,8% and 23,8% of CP respectively at the beginning of growing season.Este trabajo se realizó en tres pastizales diferentes de la provincia de La Pampa. El primero ubicado en la Ea. La Mercedes, Depto. Toay, presenta dominancia de Digitaria californica, especie de verano en la que se obtuvo 14,4% de PB. al comienzo de su período productivo. El segundo pastizal estudiado está ubicado en la Ea. La Baya Vieja, Depto. Toay, con predominio de especies invernales como Poa ligularis y Piptochaetium napostaense, en la que se obtuvieron valores de 8,5% y 12,4% de PB. respectivamente al inciarse el rebrote. El tercer pastizal estudiado está ubicado en la Ea. Los Guadales, Depto. Caleu-Caleu, con predominio de Pappophorum caespitosum en verano y con Medicago minima y Erodium cicutarium en invierno, especies en las que se obtuvieron los valores 9,8%, 24,8 y 23,8% de PB. respectivamente al iniciarse la brotación

Persistencia de los cambios provocados por los fuegos controlados en diferentes estructuras del bosque de caldén (Prosopis caldenia Burk.)

Fire may be reintroducted as prescribed burns for different purposes, mainly to remove accumulated fuels and the risk of intense fires or as a tool of range management in order to improve the forage offer. The objective of this study was to assess the vegetation response to burning 6 and 12 months after precribed fires in two different caldén woodlands: open woodland (BA) associated with torage species, and closed forest (BD) with a poor proportion of forage species a) in the community b) in the seed bank. The effect of prescribed burn in this study had less impact on the vegetation structure of both communities than expected, in terms of reduction of non palatable woody species and increasing of forage species abundance. The vegetation response is principally influenced by ils structural and floristic characteristics.La reintroducción del fuego en forma de quema prescriptas puede tener diferentes finalidades. El uso más frecuente es para la reducción de fitomasa altamente combustible, disminuyendo de esta manera los riesgos de propagación de incendio o como herramienta para mantener o aumentar la producción forrajera de las áreas. El objetivo del presente trabajo es evaluar la respuesta de la vegetación a la acción de la quema controlada en los 6 y 12 meses posteriores a la misma en dos variantes de la comunidad de bosque de caldén: bosque abierto (BA) con presencia de especies forrajeras y bosque denso (BD) con baja proporción de especies forrajeras a) en la vegetación b) en el banco de semillas de gramíneas. El efecto del fuego controlado observado en este trabajo para ambas comunidades no tuvo la magnitud de cambio estructural que se esperaba en lo que respecta a aumento de forrajeras y disminución de especies no forrajeras y leñosas. La respuesta de la vegetación estuvo principalmente condicionada por las características estructurales y florísticas de la comunidad

Crystal Structure of the Hemochromatosis Protein HFE and Characterization of Its Interaction with Transferrin Receptor

AbstractHFE is an MHC-related protein that is mutated in the iron-overload disease hereditary hemochromatosis. HFE binds to transferrin receptor (TfR) and reduces its affinity for iron-loaded transferrin, implicating HFE in iron metabolism. The 2.6 Å crystal structure of HFE reveals the locations of hemochromatosis mutations and a patch of histidines that could be involved in pH-dependent interactions. We also demonstrate that soluble TfR and HFE bind tightly at the basic pH of the cell surface, but not at the acidic pH of intracellular vesicles. TfR:HFE stoichiometry (2:1) differs from TfR:transferrin stoichiometry (2:2), implying a different mode of binding for HFE and transferrin to TfR, consistent with our demonstration that HFE, transferrin, and TfR form a ternary complex

Comportamiento de la presentación podálica en la gestante primigrávida. Resultados perinatales. Behavior of podalic presentation in primigravid woman. Perinatal results

Con la finalidad de analizar el comportamiento de los resultados perinatales en la presentación podálica en gestante sin partos y con partos, se realizó una investigación retrospectiva, transversal y analítica en el Hospital Universitario "Abel Santamaría Cuadrado" entre mayo del 2001 y diciembre del 2002. El universo de estudio lo conformaron todos los nacimientos ocurridos en la etapa analizada, mientras que la muestra quedó constituida por todos los nacimientos ocurridos con presentación podálica; este grupo se dividió en dos: el grupo "A" formado por las gestantes que no tenían partos anteriores y el grupo "B" integrado por gestantes con partos anteriores. Se analizaron diferentes variables de la madre, el parto y el recién nacido. El análisis estadístico se realizó por el porciento, la media, la desviación estándar y para la comparación de los grupos se utilizó el test de Chi Cuadrado con nivel de significación de p < 0.05. Se obtuvo asociación entre las adolescentes con presentación podálica y el grupo "A" y entre las mujeres del intervalo de 30-34 años y el grupo "B". El peso del recién nacido, el Apgar y la morbilidad no resultaron significativas estadísticamente. Se concluye que los resultados perinatales en la presentación podálica son similares tanto para las gestantes como para las que han tenido embarazos anteriores. Palabras clave: PARTO, PRESENTACIÓN EN EL TRABAJO DE PARTO. ABSTRACT In order to analyze the behaviour the perinatal results in podalic presentation in pregnants with delivery and without delivery, a retrospective, cross - sectional and analytic research was performed at Abel Santamaria University Hospital from May, 2001 and December, 2002. The universe in the study consisted of all births taking place during the analyzed period, whereas the sample comprised all births taking place with podalic presentation; this group was devided into two: group A which is formed by pregnants with no previous delivery and group B formed by pregnants with previous delivery. Defferent variates of the mother, delivery and new born were analyzed. The statistical analysis was performed by percent, mean, and standard deviation; and for comparing groups chi square test was used with a p <0.05 significance level. There was an association between adolescents with podalic presentation and group A, and between women raging from 30 to 34 years of age and group B. Post-term pregnancy was associated with previous deliveries; an association between caesarean section and group A, and eutocic delivery and group B was significant. The newborn´s weight, Apgar and morbidity did not turn out to be statistically significant. As a conclusion, perinatal results in the podalic presentation are similar both for primigravidas and for those women having previous deliveries. Key words: DELIVERY, LABOR PRESENTATION

Comportamiento de la presentación podálica en la gestante primigrávida. Resultados perinatales. Behavior of podalic presentation in primigravid woman. Perinatal results

Con la finalidad de analizar el comportamiento de los resultados perinatales en la presentación podálica en gestante sin partos y con partos, se realizó una investigación retrospectiva, transversal y analítica en el Hospital Universitario "Abel Santamaría Cuadrado" entre mayo del 2001 y diciembre del 2002. El universo de estudio lo conformaron todos los nacimientos ocurridos en la etapa analizada, mientras que la muestra quedó constituida por todos los nacimientos ocurridos con presentación podálica; este grupo se dividió en dos: el grupo "A" formado por las gestantes que no tenían partos anteriores y el grupo "B" integrado por gestantes con partos anteriores. Se analizaron diferentes variables de la madre, el parto y el recién nacido. El análisis estadístico se realizó por el porciento, la media, la desviación estándar y para la comparación de los grupos se utilizó el test de Chi Cuadrado con nivel de significación de p < 0.05. Se obtuvo asociación entre las adolescentes con presentación podálica y el grupo "A" y entre las mujeres del intervalo de 30-34 años y el grupo "B". El peso del recién nacido, el Apgar y la morbilidad no resultaron significativas estadísticamente. Se concluye que los resultados perinatales en la presentación podálica son similares tanto para las gestantes como para las que han tenido embarazos anteriores. Palabras clave: PARTO, PRESENTACIÓN EN EL TRABAJO DE PARTO. ABSTRACT In order to analyze the behaviour the perinatal results in podalic presentation in pregnants with delivery and without delivery, a retrospective, cross - sectional and analytic research was performed at Abel Santamaria University Hospital from May, 2001 and December, 2002. The universe in the study consisted of all births taking place during the analyzed period, whereas the sample comprised all births taking place with podalic presentation; this group was devided into two: group A which is formed by pregnants with no previous delivery and group B formed by pregnants with previous delivery. Defferent variates of the mother, delivery and new born were analyzed. The statistical analysis was performed by percent, mean, and standard deviation; and for comparing groups chi square test was used with a p <0.05 significance level. There was an association between adolescents with podalic presentation and group A, and between women raging from 30 to 34 years of age and group B. Post-term pregnancy was associated with previous deliveries; an association between caesarean section and group A, and eutocic delivery and group B was significant. The newborn´s weight, Apgar and morbidity did not turn out to be statistically significant. As a conclusion, perinatal results in the podalic presentation are similar both for primigravidas and for those women having previous deliveries. Key words: DELIVERY, LABOR PRESENTATION