New record of Mythapion adesmiae Kissinger, 2005 (Coleoptera: Brentidae) in Argentina

The weevil Mythapion adesmiae, previously known from Chilean Patagonia (Aysén and Magallanes regions) and the province of Santa Cruz in Argentina, is recorded for the first time for the province of Río Negro, above the treeline, between 1744-1850 m a.s.l. on Cerro Challhuaco associated with Adesmia corymbosa, which is a new plant association. The known records suggest an extensive distribution along the Patagonian Andes of Chile and Argentina.Fil: Gavini, Sabrina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Kun, Marcelo Eduardo. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche; Argentin

“La Chinche Foliada de los Pinos” Leptoglossus occidentalis

Las "chinches foliadas" son insectos pertenecientes a la familia Coreidae, un grupo diverso de heterópteros que posee una distribución cosmopolita. Desde el año 2017 se registra en la provincia de Río Negro y más recientemente también en la provincia de Neuquén. La especie es conocida como la "chinche foliada de los pinos" o "chinche de las coníferas occidental" Leptoglossus occidentalis. Nativo de América del Norte, este insecto ha invadido varias regiones del mundo. La detección en la Patagonia es muy reciente y posiblemente esté asociada al transporte desde Chile hacia el Noroeste de esta región.Estación Experimental Agropecuaria Bariloche. Área de Recursos Forestales. Grupo de Ecología de Pobalciones de InsectosFil: Kun, Marcelo. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Departamento de Zoología; Argentin

Feeding habits and their implications for the conservation of the endangered semiaquatic frog Atelognathus patagonicus (Anura, Neobatrachia) in a northwestern Patagonian pond

Feeding habits and their implications for the conservation of the endangered semiaquatic frog Atelognathus patagonicus (Anura, Neobatrachia) in a northwestern Patagonian pond. Atelognathus patagonicus (Gallardo, 1962) is an endemic frog species whose distribution is restricted to an endorheic pond system in basaltic basins in the northwest of the Argentinean Patagonia. Atelognathus patagonicus has two morphotypes: aquatic and littoral. This study presents data on the diet of A. patagonicus in Laguna del Burro, in Neuquén Province. Digestive tracts were analyzed for 20 specimens: 17 of the aquatic form and 3 of the littoral form. Diversity and trophic niche breadth, and index of relative importance (IRI) were calculated for the aquatic form. Nine food categories were found in the stomachs and intestine with the most important being Odonate naiads (Rhionaeschna sp.; IRI% = 86.57) and amphipod crustaceans (Hyalella sp.; IRI% = 12.89). There was not a statistically significant correlation between snout-vent length and mouth width of the frogs and mean prey lengths. For the littoral form of A. patagonicus, 25 prey categories were found, and all preys were adult terrestrial arthropods. Conclusions about the feeding habits of Atelognathus patagonicus and their implications for the design of conservation programs for the species are also given

Seasonal trophic activity of the aquatic morphotype of Atelognathus patagonicus (Anura, Neobatrachia) and prey availability in the littoral benthos of a permanent pond in Argentinean Patagonia

Estudamos a dieta do morfótipo aquático de Atelognathus patagonicus com base em indivíduos coletados na lagoa Laguna Verde (Laguna Blanca National Park, Neuquén, Argentina). O conteúdo gastrointestinal de 35 indivíduos pós-metamórficos (novembro de 2003 a abril de 2006) foi correlacionado com a composição do bentos em seu micro-habitat. O número, o tamanho, a ocorrência e a importância relativa das presas, a diversidade da dieta, a amplitude do nicho trófico e a eletividade foram estimados para cada estação do ano. A dieta consistiu de artrópodes aquáticos. A composição do bentos e da dieta (número e ocorrência de organismos na dieta) foram dominadas pelo anfípode Hyalella sp. A importância relativa (IRI) de Hyalella sp. na dieta foi maior que 99% no verão e no outono e de 100% no inverno e na primavera. Diptera e Copepoda no verão e Dytiscidae e Ostracoda no outono tiveram valores sazonais de IRI < 0,2%. A amplitude do nicho trófico foi muito baixa no verão e no outono e nula (= 0) no inverno e na primavera. O número médio de presas por indivíduo foi maior na primavera (19) e menor no inverno (4). Os anuros continuaram a se alimentar no inverno, mesmo após o congelamento da superfície da lagoa. Há uma correspondência entre o principal item alimentar desses anuros e sua presença no bentos.The diet of the aquatic morphotype of Atelognathus patagonicus was studied in frogs collected from the Laguna Verde pond (Laguna Blanca National Park, Neuquén, Argentina). The content of 35 gastrointestinal tracts of post-metamorphic specimens from November 2003 to April 2006 was related to the composition of the benthos in their microhabitat. Number, size, occurrence and relative importance of preys, diversity of the diet, trophic niche breadth and electivity were estimated for each season of the year. The diet consisted of aquatic arthropods. The composition of both the benthos and the food (number and occurrence of organisms in the diet) were dominated by the amphipod Hyalella sp. The relative importance (IRI) of Hyalella sp. in the diet was over 99% in summer and autumn, and 100% in winter and spring. Diptera and Copepoda in summer, and Dytiscidae and Ostracoda in autumn, had seasonal IRI values < 0.2%. Trophic niche breadth was very low in summer and autumn, and null (= 0) in winter and spring. The mean number of preys per individual was highest in spring (19 preys/frog) and lowest in winter (4 preys/frog). Frogs continued with their trophic activity in winter, even when the surface of the pond was frozen. There is a correspondence between the frogs' main food item and its presence in the benthos

Myiasis gastrointestinal humana por Eristalis tenax

The myiasis observed in Bariloche are characterized and the probable conditions under which the infestations took place established. The larvae obtained from faeces of 2 patients were identified as Eristalis tenax (Diptera: Syrphidae) according to Hartley (1961) and Organización Panamericana de la Salud keys (1962). These 2 cases of human gastrointestinal myiasis were the first to be registered in Bariloche (Patagonia, Argentina) and their characteristics were similar to those described for this species in other parts of the world. The lack of specific control measures in the domestic water supply system was the most probable cause of the infestation. This event extends the distribution of E. tenax and human gastrointestinal myiasis in South America to 41º 03' S.Son caracterizadas las myiasis registradas en Bariloche y establecidas las condiciones probables bajo las cuales se produjeron las infestaciones. Las larvas obtenidas a partir de heces de 2 pacientes fueron identificadas como Eristalis tenax (Diptera: Syrphidae) de acuerdo a las claves de Hartley (1961) y Organización Panamericana de la Salud (1962). Estos 2 casos de myiasis gastrointestinal humana constituyen los primeros registrados en Bariloche (Patagonia, Argentina) y sus características responden a las registradas para esta especie de Díptera en otras partes del mundo. La falta de control específico en el sistema domiciliario de suministro de agua ha sido la causa más probable de la infestación. Este registro extiende la distribución de E. tenax y de las myiasis gastrointestinales humanas en América del Sur hasta los 41º 03' S.Foram caracterizadas as miasis registradas em Bariloche (Patagonia, Argentina) e estabelecidas as prováveis condições sob as quais são produzidas as infestações. As larvas obtidas a partir das fezes de dois pacientes foram identificadas como Eristalis tenax (Diptera: Syrphdae). Esses dois casos de miasis gastrointestinal humana foram os primeiros registrados em Bariloche, Argentina, e suas características respondem às registradas para esta espécie de Diptera em outras partes do mundo. A falta de controle específico no sistema domiciliário de abastecimento de água tem sido a causa mais provável de infestação. Este registro amplia a distribuição de E. tenax e das miasis gastrointestinais humanas em América do Sul até os 41º 03's

Gibbs Paradox and Similarity Principle

As no heat effect and mechanical work are observed, we have a simple experimental resolution of the Gibbs paradox: both the thermodynamic entropy of mixing and the Gibbs free energy change are zero during the formation of any ideal mixtures. Information loss is the driving force of these spontaneous processes. Information is defined as the amount of the compressed data. Information losses due to dynamic motion and static symmetric structure formation are defined as two kinds of entropies - dynamic entropy and static entropy, respectively. There are three laws of information theory, where the first and the second laws are analogs of the two thermodynamic laws. However, the third law of information theory is different: for a solid structure of perfect symmetry (e.g., a perfect crystal), the entropy (static entropy for solid state) S is the maximum. More generally, a similarity principle is set up: if all the other conditions remain constant, the higher the similarity among the components is, the higher the value of entropy of the mixture (for fluid phases) or the assemblage (for a static structure or a system of condensed phases) or any other structure (such as quantum states in quantum mechanics) will be, the more stable the mixture or the assemblage will be, and the more spontaneous the process leading to such a mixture or an assemblage or a chemical bond will be.Comment: Final version 12 pages, 10 figures, presented at MaxEnt200

Biological collection of insects: from collection to conservation

Las colecciones biológicas son bibliotecas de especímenes que representan la principal fuente de información sobre la biodiversidad de una región. Estos archivos históricos permiten realizar estudios de taxonomía, fisiología y ecología, entre otros, que son fundamentales para impulsar medidas de conservación medioambiental. En este artículo hacemos énfasis en las colecciones entomológicas, que pueden ser generadas sin afectar sus poblaciones. Asimismo, las colecciones sin fines científicos son una problemática que amenaza a vistosos y escasos insectos. Concluimos que la divulgación y exhibición de las colecciones biológicas es uno de los puntos de partida para la conservación de la biodiversidad del planeta.Biological collections are libraries of specimens that represent the main source of information about the biodiversity of a region. These historical archives allow us to carry out studies of taxonomy, physiology and ecology, among others, which are fundamental when promoting measures for environmental conservation. In this article we emphasize the entomological collections that can be generated without affecting their populations. Likewise, collections with no scientific purpose are a problem that threatens the attractive and scarce insects. We conclude that the divulgation and exhibition of biological collections is one of the starting points for the conservation of the planet's biodiversity.Fil: García, Roberto Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Villagrán, Matías. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche; ArgentinaFil: Wittner Fernández, Daniel Nicolás. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche; ArgentinaFil: Kun, Marcelo Eduardo. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche; Argentin

Antagonistic Mixing in Micelles of Amphiphilic Polyoxometalates and Hexaethylene Glycol Monododecyl Ether

International audienceHypothesis: Polyoxometalates (POMs) are metal oxygen clusters with a range of interesting magnetic and catalytic properties. POMs with attached hydrocarbon chains show amphiphilic behaviour so we hypothesised that mixtures of a nonionic surfactant and anionic surfactants with a polyoxometalate cluster as headgroup would form mixed micelles, giving control of the POM density in the micelle, and which would differ in size and shape from micelles formed by the individual surfactants. Due to the high charge and large size of the POM, we suggested that these would be nonideal mixtures due to the complex interactions between the two types of surfactants. The nonideality and the micellar composition may be quantified using regular solution theory. With supplementary information provided by small-angle neutron scattering (SANS), an understanding of this unusual binary surfactant system can be established.Experiments: A systematic study was performed on mixed surfactant systems containing polyoxometalate-headed amphiphiles (K10[P2W17O61OSi2(CnH(2n+1))2], abbreviated as P2W17-2Cn, where n = 12, 14 or 16) and hexaethylene glycol monododecyl ether (C12EO6). Critical micelle concentrations (CMCs) of these mixtures were measured and used to calculate the interaction parameters based on regular solution theory, enabling prediction of micellar composition. Predictions were compared to micelle structures obtained from SANS. A phase diagram was also established.Findings: The CMCs of these mixtures suggest unusual unfavourable interactions between the two species despite formation of mixed micelles. Micellar compositions obtained from SANS concurred with those calculated using the averaged interaction parameters for P2W17-2Cn/C12EO6 (n = 12 and 14). We attribute the unfavourable interactions to a combination of different phenomena: counterion-mediated interactions between P2W17 units and the unfolding of the ethylene oxide headgroups of the nonionic surfactant, yet micelles still form in these systems due to the hydrophobic interactions between surfactant tails

Keys for the identification of genera and species of limnoterrestrial tardigrades (Tardigrada) from the Parque Nacional Nahuel Huapi and surroundings (Patagonia, Argentina)

La información acerca de la diversidad del Phylum Tardigrada en la Argentina yen particular en la región patagónica se encuentra fragmentada y dispersa. En esta contribución se presenta una clave para la identificación de los 23 géneros y 49 especies de tardígrados limnoterrestres registrados hasta el momento en el área del Parque Nacional Nahuel Huapi y sus alrededores.The information about the diversity of the Phylum Tardigrada in Argentina and particularly in the Patagonian region is fragmented and dispersed. In this contribution, keys for the identification of the 23 genera and 49 species of limnoterrestrial tardigrades registered up to now in the area of the Nahuel Huapi National Park and surroundings are presented.Fil: Meier, María Florencia. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche; ArgentinaFil: Rocha, Alejandra Mariana. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Biológicas; ArgentinaFil: Kun, Marcelo Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Messuti, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentin

Canonical and Atypical E2Fs Regulate the Mammalian Endocycle

SUMMARY The endocycle is a variant cell cycle consisting of successive DNA synthesis and Gap phases that yield highly polyploid cells. Although essential for metazoan development, relatively little is known about its control or physiologic role in mammals. Using novel lineage-specific cre mice we identified two opposing arms of the E2F program, one driven by canonical transcription activation (E2F1, E2F2 and E2F3) and the other by atypical repression (E2F7 and E2F8), that converge on the regulation of endocycles in vivo. Ablation of canonical activators in the two endocycling tissues of mammals, trophoblast giant cells in the placenta and hepatocytes in the liver, augmented genome ploidy, whereas ablation of atypical repressors diminished ploidy. These two antagonistic arms coordinate the expression of a unique G2/M transcriptional program that is critical for mitosis, karyokinesis and cytokinesis. These results provide in vivo evidence for a direct role of E2F family members in regulating non-traditional cell cycles in mammals