Auxin-induced SCFTIR1-Aux/IAA interaction involves stable modification of the SCFTIR1 complex

The plant hormone auxin can regulate gene expression by destabilizing members of the Aux/IAA family of transcriptional repressors. Auxin-induced Aux/IAA degradation requires the protein-ubiquitin ligase SCFTIR1, with auxin acting to enhance the interaction between the Aux/IAAs and SCIFTIR1. SKP1, Cullin, and an F-box-containing protein (SCF)-mediated degradation is an important component of many eukaryotic signaling pathways. In all known cases to date, the interaction between the targets and their cognate SCFs is regulated by signal-induced modification of the target. The mechanism by which auxin promotes the interaction between SCFTIR1 and Aux/IAAs is not understood, but current hypotheses propose auxin-induced phosphorylation, hydroxylation, or proline isomerization of the Aux/IAAs. We found no evidence to support these hypotheses or indeed that auxin induces any stable modification of Aux/IAAs to increase their affinity for SCFTIR1. Instead, we present data suggesting that auxin promotes the SCIFTIR1-Aux/IAA interaction by affecting the SCIF component, TIR1, or proteins tightly associated with it

Utilización de Lactuca sativa y Panagrellus redivivus para el estudio ecotoxicológico de los ríos Salado y Negro (Chaco, Argentina)

Los ríos Salado y Negro corren por la planicie del Chaco Oriental. El primero atraviesa campos naturales usados para la ganadería donde la ocupación humana es baja. El segundo, un afluente del río Paraná altamente poblado, recibe efluentes urbanos e industriales. La inundación en la región es distintivamente estacional dependiendo de las lluvias de verano. En aguas bajas ambos ríos tienden a ser poco profundos y la concentración salina aumenta. En este estudio usamos bioensayos con Lactuca sativa y Panagrellus redivivus para determinar la toxicidad de los sedimentos y del agua de ambos ríos durante aguas altas y bajas. El bioensayo con lechuga está basado en la habilidad de las semillas para germinar y producir raíces al entrar en contacto con la solución problema. En el ensayo con nemátodos, el crecimiento y desarrollo de los organismos es lento o se detiene bajo condiciones adversas del medio. En Puerto Tiro! (río Negro) hubo decrecimiento de la maduración de los nemátodos y de la elongación de la raíz respecto del control (efectos subletales) usando agua sin tratamiento, extracto de sedimentos y agua concentrada (5 veces). En el río Salado los efectos subletales fueron medidos sólo en la fase de aguas bajas usando agua concentrada y extracto de sedimentos. Se discute la utilidad de ambos bioensayos en ríos que presentan fases de aguas bajas con alta salinidad

Use of Red Cactus Pear (Opuntia ficus-indica) Encapsulated Powder to Pigment Extruded Cereal

Encapsulated powder of the red cactus pear is a potential natural dye for the food industry and a known antioxidant. Although the use of this powder is possible, it is not clear how it alters food properties, thus ensuing commercial acceptability. The aim of thisstudywastoevaluatetheeffectofencapsulatedpowderoftheredcactuspearonthephysicochemicalpropertiesofextruded cereals. The powder was mixed (2.5, 5.0, and 7.5% w/w) with maize grits and extruded (mix moisture 22%, temperature 100∘C, and screw speed 325rpm). The physical, chemical, and sensory characteristics of the extruded cereal were evaluated; extruded cerealwithoutencapsulatedpowderwasusedasacontrol.Allcerealextrudatespigmentedwiththeencapsulatedpowdershowed statisticallysignificantdifferences

Caracterización físico-química de ambientes acuáticos permanentes y temporarios del Chaco Oriental

Physico-chemical characteristies of 17 strearas and 3 tropical swamps-so called "esteros"- were studied in the provinces of Santa Fe, Chaco and Formosa in the esastern Chaco (Argentine). This study was done in order to gather suitable information about the availability of regional hydric re-sources, to determine the possible utilization and to contribute to the improvement of the landscape management. In the initial stage, samples were analyzed in three different opportunities during the hydrologic cycle, including dry and flooded seasons. The paper describes seasonal variations of the salinity, major ion composition, expressed as the porcentage of equivalent sum of total cations or anions, their geographical distribution and some other features, as the nutrient levels,hardness and aptitude for irrigation. On this basis, a characterization of the differents habitats is given also considering the most distinctive physico-chemical features. Analysis have been made according with the methodology described in Standard Methods (APHA, 1975) and Golterman and Clymo (IBP, 1978). Among the obtained records, the most relevant was the one concerning with the salinization phenomena being frequent in the Salado, Saladito, Saladillo and Palometa streams. In low water periods, they increased the conductivity to 103 uS.cm-1, with the correlative increment in the sodium, chloride and sulfate concentration which determined changes in the ionic typology.Physico-chemical characteristies of 17 strearas and 3 tropical swamps-so called "esteros"- were studied in the provinces of Santa Fe, Chaco and Formosa in the esastern Chaco (Argentine). This study was done in order to gather suitable information about the availability of regional hydric re-sources, to determine the possible utilization and to contribute to the improvement of the landscape management. In the initial stage, samples were analyzed in three different opportunities during the hydrologic cycle, including dry and flooded seasons. The paper describes seasonal variations of the salinity, major ion composition, expressed as the porcentage of equivalent sum of total cations or anions, their geographical distribution and some other features, as the nutrient levels,hardness and aptitude for irrigation. On this basis, a characterization of the differents habitats is given also considering the most distinctive physico-chemical features. Analysis have been made according with the methodology described in Standard Methods (APHA, 1975) and Golterman and Clymo (IBP, 1978). Among the obtained records, the most relevant was the one concerning with the salinization phenomena being frequent in the Salado, Saladito, Saladillo and Palometa streams. In low water periods, they increased the conductivity to 103 uS.cm-1, with the correlative increment in the sodium, chloride and sulfate concentration which determined changes in the ionic typology

Calidad del agua en el tramo bajo del Río Negro (Chaco, Argentina)

Las principales características físicas, químicas y biológicas fueron medidas entre noviembre de 1999 y mayo de 2002 en 4 sitios ubicados en el cauce principal del río Negro. En los sitios 1 y 2 los humedales y bosques con baja ocupación humana constituyen el paisaje característico que bordea al curso principal. Los sitios 3 y 4 están afectados por descargas domésticas e industriales, aunque la producción de tanino fue de menor volumen en los últimos años. La composición química del agua superficial estuvo influenciada por la estacionalidad de las lluvias y el lavado de suelos ricos en sales de los humedales hacia el canal del río. La conductividad eléctrica del agua durante las sequías fue más alta que la registrada después de las lluvias. La salinidad fluctuó de manera semejante entre 82,7 mg.l-1 y 6500 mg.l-1. La concentración promedio de fósforo total fue alta (1053 µg.l-1) y el pH neutro o ligeramente alcalino. En el sitio 4, el contenido de materia orgánica (DQO=385 mg.l-1) aumentó significativamente durante el periodo de aguas bajas. No se encontraron residuos de 27 plaguicidas y compuestos organoclorados en los sedimentos del fondo de los sitios muestreados. El contenido de Plomo y Cadmio de los sedimentos estuvo debajo del límite de detección. Los valores de Cromo varió entre 14 y 22 µg.g de sedimento seco, dependiendo del sitio estudiado. Diez especies de plantas acuáticas fueron recolectadas en el Sitio 1 que se caracterizó por baja velocidad de flujo. La riqueza de macrófitas disminuyó aguas abajo. La ocurrencia de algunas especies, tales como Hydrocotyle ranunculoides y Ceratophyllum demersum, estuvo relacionada con la buena disponibilidad de fósforo. La biomasa de algas indicada por la concentración de clorofila a fue baja en todos los sitios estudiados (inferior a 20 µg.l-1)

A combinatorial TIR1/AFB–Aux/IAA co-receptor system for differential sensing of auxin

The plant hormone auxin regulates virtually every aspect of plant growth and development. Auxin acts by binding the F-box protein transport inhibitor response 1 (TIR1) and promotes the degradation of the AUXIN/INDOLE-3-ACETIC ACID (Aux/IAA) transcriptional repressors. Here we show that efficient auxin binding requires assembly of an auxin co-receptor complex consisting of TIR1 and an Aux/IAA protein. Heterologous experiments in yeast and quantitative IAA binding assays using purified proteins showed that different combinations of TIR1 and Aux/IAA proteins form co-receptor complexes with a wide range of auxin-binding affinities. Auxin affinity seems to be largely determined by the Aux/IAA. As there are 6 TIR1/AUXIN SIGNALING F-BOX proteins (AFBs) and 29 Aux/IAA proteins in Arabidopsis thaliana, combinatorial interactions may result in many co-receptors with distinct auxin-sensing properties. We also demonstrate that the AFB5–Aux/IAA co-receptor selectively binds the auxinic herbicide picloram. This co-receptor system broadens the effective concentration range of the hormone and may contribute to the complexity of auxin response

Effect of Extrusion Cooking on Bioactive Compounds in Encapsulated Red Cactus Pear Powder

Red cactus pear has significant antioxidant activity and potential as a colorant in food, due to the presence of betalains. However, the betalains are highly thermolabile, and their application in thermal process, as extrusion cooking, should be evaluated. The aim of this study was to evaluate the effect of extrusion conditions on the chemical components of red cactus pear encapsulated powder. Cornstarch and encapsulated powder (2.5% w/w) were mixed and processed by extrusion at different barrel temperatures (80, 100, 120, 140 °C) and screw speeds (225, 275, 325 rpm) using a twin-screw extruder. Mean residence time (trm), color (L*, a*, b*), antioxidant activity, total polyphenol, betacyanin, and betaxanthin contents were determined on extrudates, and pigment degradation reaction rate constants (k) and activation energies (Ea) were calculated. Increases in barrel temperature and screw speed decreased the trm, and this was associated with better retentions of antioxidant activity, total polyphenol, betalain contents. The betacyanins k values ranged the −0.0188 to −0.0206/s and for betaxanthins ranged of −0.0122 to −0.0167/s, while Ea values were 1.5888 to 6.1815 kJ/mol, respectively. The bioactive compounds retention suggests that encapsulated powder can be used as pigments and to provide antioxidant properties to extruded products

Revisiting Coupling Selection Rules in Heterotic Orbifold Models

We study L-point couplings between twisted sector fields in heterotic orbifold compactifications, using conformal field theory. Selection rules provide an easy way to identify which couplings are non-vanishing. Those used in the current literature are gauge invariance, R-charge conservation and the space group selection rule, but they are not the whole story. We revive and refine a fourth selection rule, due to symmetries in the underlying torus lattice, and introduce a fifth one, due to the existence or not of classical worldsheet instanton solutions to mediate the couplings. We consider briefly the phenomenological consequences of the additional rules, in particular for recent orbifold constructions whose field content correspond to that of the MSSM. The structure of the exotic mass matrices is unaltered and many dimension-5 proton-decay operators vanish.Comment: 27 pages, v2: several clarifications, matches JHEP version. v3: supercedes journal version, erratum to appear in JHEP; correction to "rule 5" equations, main ideas unchange

Rarity of monodominance in hyperdiverse Amazonian forests.

Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such "monodominant" forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tree Diversity Network (ATDN). Utilizing a simple defining metric of at least half of the trees ≥ 10 cm diameter belonging to one species, we found only a few occurrences of monodominance in Amazonia, and the phenomenon was not significantly linked to previously hypothesized life history traits such wood density, seed mass, ectomycorrhizal associations, or Rhizobium nodulation. In our analysis, coppicing (the formation of sprouts at the base of the tree or on roots) was the only trait significantly linked to monodominance. While at specific locales coppicing or ectomycorrhizal associations may confer a considerable advantage to a tree species and lead to its monodominance, very few species have these traits. Mining of the ATDN dataset suggests that monodominance is quite rare in Amazonia, and may be linked primarily to edaphic factors

Mixed cryoglobulinemia

Mixed cryoglobulinemia (MC), type II and type III, refers to the presence of circulating cryoprecipitable immune complexes in the serum and manifests clinically by a classical triad of purpura, weakness and arthralgias. It is considered to be a rare disorder, but its true prevalence remains unknown. The disease is more common in Southern Europe than in Northern Europe or Northern America. The prevalence of 'essential' MC is reported as approximately 1:100,000 (with a female-to-male ratio 3:1), but this term is now used to refer to a minority of MC patients only. MC is characterized by variable organ involvement including skin lesions (orthostatic purpura, ulcers), chronic hepatitis, membranoproliferative glomerulonephritis, peripheral neuropathy, diffuse vasculitis, and, less frequently, interstitial lung involvement and endocrine disorders. Some patients may develop lymphatic and hepatic malignancies, usually as a late complication. MC may be associated with numerous infectious or immunological diseases. When isolated, MC may represent a distinct disease, the so-called 'essential' MC. The etiopathogenesis of MC is not completely understood. Hepatitis C virus (HCV) infection is suggested to play a causative role, with the contribution of genetic and/or environmental factors. Moreover, MC may be associated with other infectious agents or immunological disorders, such as human immunodeficiency virus (HIV) infection or primary Sjögren's syndrome. Diagnosis is based on clinical and laboratory findings. Circulating mixed cryoglobulins, low C4 levels and orthostatic skin purpura are the hallmarks of the disease. Leukocytoclastic vasculitis involving medium- and, more often, small-sized blood vessels is the typical pathological finding, easily detectable by means of skin biopsy of recent vasculitic lesions. Differential diagnoses include a wide range of systemic, infectious and neoplastic disorders, mainly autoimmune hepatitis, Sjögren's syndrome, polyarthritis, and B-cell lymphomas. The first-line treatment of MC should focus on eradication of HCV by combined interferon-ribavirin treatment. Pathogenetic treatments (immunosuppressors, corticosteroids, and/or plasmapheresis) should be tailored to each patient according to the progression and severity of the clinical manifestations. Long-term monitoring is recommended in all MC patients to assure timely diagnosis and treatment of the life-threatening complications. The overall prognosis is poorer in patients with renal disease, liver failure, lymphoproliferative disease and malignancies