Acclimation responses of Arabidopsis thaliana to sustained phosphite treatments

Phosphite () induces a range of physiological and developmental responses in plants by disturbing the homeostasis of the macronutrient phosphate. Because of its close structural resemblance to phosphate, phosphite impairs the sensing, membrane transport, and subcellular compartmentation of phosphate. In addition, phosphite induces plant defence responses by an as yet unknown mode of action. In this study, the acclimation of Arabidopsis thaliana plants to a sustained phosphite supply in the growth medium was investigated and compared with plants growing under varying phosphate supplies. Unlike phosphate, phosphite did not suppress the formation of lateral roots in several Arabidopsis accessions. In addition, the expression of well-documented phosphate-starvation-induced genes, such as miRNA399d and At4, was not repressed by phosphite accumulation, whilst the induction of PHT1;1 and PAP1 was accentuated. Thus, a mimicking of phosphate by phosphite was not observed for these classical phosphate-starvation responses. Metabolomic analysis of phosphite-treated plants showed changes in several metabolite pools, most prominently those of aspartate, asparagine, glutamate, and serine. These alterations in amino acid pools provide novel insights for the understanding of phosphite-induced pathogen resistance

Feixes de Restinga da Ilha de Santa Catarina, Brasil

Beach ridge sands from the northern beaches of Santa Catarina Island (Florianópolis), Brazil, are studied by considering their textural and mineralogical properties. Grain size analysis shows that sedimenst are fine sands (Mz = 2,500-2,266), very well sorted (=0,343-0,258) and both positive (Jurerê beach), and negative (Canasvieiras beach) skewed. Sphericity and roundness indices, and the prevailing surface texture reveal that the samples are on the mature to supermature development stage (FOLK, 1951)5 . Primary structures are represented by laminar bedding dipping 3-4º seaward and cut-and-fill cross-bedding.Areias de feixes de restinga da extremidade norte da Ilha de Santa Catarina (Florianópolis) foram analisadas e estudadas em suas propriedades texturais e mineralógicas. Dois locais foram amostrados (praias de Jurerê e Canasvieiras), e as análises revelam que os sedimentos são constituídos por areias finas (Mz entre 2,50 e 2,26), muito bem classificadas (0,34-0,25) e de assimetria ora positiva (Jurerê) ora negativa (Canasvieiras). Os índices de esfericidade, arredondamento e textura superficial mostram que os sedimentos situam-se no estágio de maturidade à supermaturidade (FOLK, 1951)5. As areias são dominantemente quartzosas, com pouca incidência de fragmentos de conchas e incidência relativamente acentuada de minerais pesados. As estruturas primárias presentes são representadas homogeneamente por uma acamadamento paralelo, sub-laminado, sub-horizontal (3-4º para o mar) e simples. Alguns casos de estratificação cruzada do tipo > foram constados

Structural, petrographic and geochemical characteristics of mafic dikes intrusive in metasedimentary rocks of the Crixás greenstone belt, Goiás

Mafic dikes and stocks are a common feature in the Archean terrain of Goiás, Central Brazil, where they occur as swarms of 2.3 - 2.5 Ga within the granite-gneiss complexes (2.8 e 2.7 Ga), as well as intrusions related to the komatiite and basalt flows of the greenstone belts lower stratigraphic units, but were unknown within the upper metasedimentary units. Detailed study of core sections from several drill-sites in the area of the Crixás greenstone belt gold deposits showed that dike intrusion occurred after the main Paleoproterozoic deformation and metamorphism of the metasedimentary units, and literature data indicate that the magmatic zircons from the dikes yielded an age of 2,170 ± 17 Ma. Petrographic and geochemical data show that they have the composition of epicratonic high-Ti diabases, which are similar to the large continental flood basalts of the Paraná Basin. The age of the intrusions may be correlated with the short time-interval of the Rhyacian (2.20 to 2.17 Ga), during which successive localized episodes of mantle plume volcanism occurred on the Earth.Diques e raros stocks máficos são comuns nos terrenos arqueanos de Goiás, onde ocorrem em enxames de 2.3 - 2.5 Ga nos complexos granito-gnáissicos (2.8 e 2.7 Ga) e nas seções estratigráficas inferiores de metakomatiitos e metabasaltos, mas eram desconhecidos nas unidades metassedimentares superiores dos greenstone belts. O detalhamento de seções de sondagem de área dos depósitos auríferos do greenstone belt de Crixás revelou que a intrusão destes diques ocorreu após os principais eventos de deformação e metamorfismo paleoproterozoicos da seção metassedimentar e sobre os quais dados de literatura indicam que zircão magmático dos mesmos possui a idade de 2170 ± 17 Ma. Dados petrográficos e geoquímicos registram tratar-se de diabásios com características composicionais de basaltos epicratônicos de alto-Ti semelhantes aos da Bacia do Paraná. A idade das intrusões se correlaciona com o curto intervalo de tempo (2,20 a 2,17 Ga) do Rhyaciano, durante o qual ocorreram sucessivos e localizados episódios de plumas mantélicas no Globo Terrestre

Cálculos Petroquímicos Segundo o Sistema de Niggli por Computador IBM - 1130

Os autores apresentam um programa em linguagem Fortran para uso em computador IBM-1130 a fim de proceder ao cálculo de parâmetros petrológicos, obedecendo ao Sistema de Niggli, conforme publicado por Burri (1959), e compreendendo a obtenção dos números de Niggli, dos valores para estudos das relações composicionais e quantitativas de feldspatos normativos e outros parâmetros similares, da base, da catanorma padrão e dos parâmetros para uso no triângulo QLM. Os autores anunciam, ao mesmo tempo, a preparação de programas com finalidades similares, visando a obtenção das variantes mineralógicas da catanorma padrão do Sistema de Niggli

Neoproterozoic anatexis of 2.9 Ga old granitoids in the Goiás-Crixás archean block, Central Brazil: evidence from new SHRIMP U-Pb data and Sm-Nd isotopes

The first SHRIMP U-Pb ages for granitoid rocks from the southern part of the Goiás-Crixás Archean Block (Caiçara and Uvá complexes) are presented and discussed in combination with Sm-Nd isotopic data in order to elucidate the main aspects of the geological evolution of that part of the Brasília Belt in central Brazil. Zircon grains from a tonalitic gneiss (GOV-4) in the Uvá Complex show that the original tonalite crystallized at 2934 ± 5 Ma. One metamorphic zircon crystal is concordant and indicates an Archean age for the recrystallization episode (2793 ± 3 Ma) and one inherited grain with an age of 3092 ± 9 suggests, together with negative values of µNd(T) (+0.4 and -4.6), that the magma was contaminated with older crust. One leucocratic granite (GOV-1) exposed north of the Goiás greenstone belt crystallized at 626 ± 7 Ma, as indicated by the igneous overgrowths surrounding older inherited cores. The latter indicate a crystallization age of 2893 ± 12 Ma. This rock is interpreted therefore as the product of Neoproterozoic anatexis of ca. 2.89 Ga-old rocks of the Caiçara Complex. This is reinforced by strongly negative µNd(T = 626) values of - 28.0 and -29.0. Its crystallization age is identical to the U-Pb ages of the Itapuranga granite and Uruana quartz syenite, which are exposed to the north of the investigated area and interpreted as syn-tectonic intrusions in relation to the main Brasiliano tectonic event. This represents, therefore, the first evidence of Neoproterozoic magmatism within the Goiás Archean Block and raises the possibility that other leucogranite dykes and stocks identified regionally may also have been formed during the Brasiliano orogeny.No presente estudo são reportadas as primeiras idades U-Pb SHRIMP para rochas granito-gnáissicas dos complexos Uvá e Caiçara, na parte sul dos terrenos arqueanos de Goiás. Combinados com análises isotópicas Sm-Nd, os dados U-Pb permitem aprofundar o conhecimento a respeito da evolução geológica daquela parte da Faixa Brasília. Cristais de zircão do gnaisse tonalítico de Uvá (GOV-4) indicam a idade de 2934 ± 5 Ma para a cristalização do protólito ígneo. Um grão de zircão metamórfico sugere idade de 2793 ± 3 Ma para o metamorfismo que afetou a rocha, enquanto que um grão herdado de zircão com idade de 3092 ± 9, aliado a valores de µNd(T) variando entre +0,4 e -4,6, sugere contaminação com crosta continental mais antiga. Granito leucocrático exposto a norte do greenstone belt de Crixás no Complexo Caiçara apresenta idade de cristalização de 626 ± 7 Ma, dada por sobrecrescimentos ígneos cristalizados em torno de núcleo com idade de 2893 ± 12 Ma. O resultado, combinado com valores fortemente negativos de µNd(T) (entre -28,0 e -29,0), indica que o granito é produto de refusão de rochas arqueanas com ca. 2,89 Ga de idade. A idade do granito é idêntica às idades U-Pb SHRIMP e convencional do álcali-granito Itapuranga e quartzo sienito de Uruana, expostos a norte da área estudada. Trata-se, portanto, do primeiro registro confiável de magmatismo Neoproterozóico no interior dos terrenos arqueanos de Goiás e pode sinalizar que vários dos pequenos corpos e diques de leucogranitos encontrados em meio aos terrenos TTG podem representar magmas gerados durante a orogênese brasiliana

Stratigraphy and geochronlogy of the Guarinos greenstone belt, Goiás, Brazil

O greenstone belt de Guarinos é uma das três faixas de rochas supracrustais de baixo grau metamórfico marginadas por ortognaisses do extremo norte do Bloco Arqueano de Goiás. A investigação da estratigrafia daquelas faixas iniciou no final da década de 1970, com modificações ao longo dos anos em decorrência de mapeamentos geológicos de detalhe. A proposta estratigráfica mais recente em vigor do greenstone belt de Guarinos reúne as rochas supracrustais no Grupo Guarinos, subdividido nas formações Serra do Cotovelo (metakomatiitos), Serra Azul (metabasaltos), São Patricinho (metaturbiditos máficos), Aimbé (BIF) e Cabaçal (filitos carbonosos e metarenitos impuros). O mapeamento de detalhe e os resultados de sondagens do programa de exploração mineral na área pela Yamana Desenvolvimento Mineral S.A. possibilitaram redefinir a Formação Cabaçal e desdobrá-la em um membro inferior de filitos carbonosos com intercalações de derrames de basalto e lentes de gondito; um intermediário de horizonte de gondito e formação ferrífera com metachert e barita maciça; e um superior de filito carbonoso com eventuais lentes de metachert. Os metarenitos impuros, por seu turno, são propostos sob a denominação de Formação Mata Preta, a qual está lateralmente interdigitada com as rochas da Formação Cabaçal. Dados geocronológicos U-Pb obtidos por LA-ICP-MS em cristais detríticos de zircão dos turbiditos máficos da Formação São Patricinho e dos metarenitos da Formação Mata Preta indicam área fonte dominada por rochas do Sideriano e Riaciano, com parcial participação de fonte Arqueana. A natureza dos litotipos das formações Cabaçal e Mata Preta e as relações de contato entre ambas sugerem que o estágio de bacia que representam evoluiu a partir de importante evento anóxico oceânico mundial de 2,2 a 2,06 Ga e responsável pela Formação Cabaçal. O ambiente euxênico foi contemporâneo com um arco magmático que atuou como fonte da carga clástica dos arenitos da Formação Mata Preta.The Guarinos greenstone belt is one of the three low metamorphic grade supracrustal rocks assemblage rimmed by orthogneisses of Central Brazil's Archean Block northern limits. The investigation of the stratigraphy of those greenstone belts started by the end of 1970's and underwent improvements during the years as a result of detailed geological mapping. The latest and accepted stratigraphic model for the Guarinos greenstone belt refers its supracrustal rocks under the Guarinos Group, which is subdivided into the Serra do Cotovelo (metakomatiites), Serra Azul (metabasalts), São Patricinho (mafic metaturbidites), Aimbé (BIF) and Cabaçal (carbonaceous phyllites and impure metarenites) formations. Detailed geologic mapping (1:10,000) and drill-cores during an exploration program by Yamana Desenvolvimento Mineral S.A. in the area allowed a better definition of the metasedimentary package of the Cabaçal Formation, which is here formally proposed to be subdivided into a Lower Member of carbonaceous phyllites with basalt lava flows and gondite lenses interlayers, an Intermediate Member of gondite, iron formation, metachert and massive barite lenses, and an Upper Member of carbonaceous phyllites with minor metachert lenses. The impure metarenites, formerly considered as part of the Cabaçal Formation, are proposed under the Mata Preta Formation, which is laterally interfingered with the Cabaçal Formation. U-Pb LA-ICP-MS geochronological data of detrital zircon grains from the São Patricinho mafic metaturbidites and the impure metarenites of the Mata Preta formations indicate that the major source-area of the clastic load had a Siderian to Rhyacian age, with minor contribution from Archean rocks. From the rock assemblage of both units and their contact relationships it is concluded that the basin stage they represent evolved during the world-wide Anoxic Oceanic Event (AOE) that took place during the 2.2 to 2.06 Ga, represented by the carbonaceous phyllites of the Cabaçal Formation, coeval with the erosion of a magmatic arc that derived the immature clastic load of the Mata Preta Formation

Geochemistry and isotopic signatures of metavolcanic and metaplutonic rocks of the Faina and Serra de Santa Rita greenstone belts, Central Brazil : evidences for a Mesoarchean intraoceanic arc.

The Archean-Paleoproterozoic Terrane of Goi?s, Central Brazil, is an allochthonous block within the Neoproterozoic Tocatins Province and consists of an association of Archean TTG complexes and goldbearing Archean-Paleoproterozoic greenstone belts. The Faina and Serra Santa Rita greenstone belts, located in the southern portion of the terrane, are investigated using geochemistry and isotope geology to establish the time of magmatism and tectonic environment. Our data show that the ultramafic rocks have some chemical characteristics similar to modern boninites, whereas the amphibolites are subdivided into two groups: the type 1 basalts group are tholeiites with flat REE patterns and are similar to back-arc basin basalts; the type 2 basalts group have high Nb contents and are comparable to Nbenriched basalts. Felsic to intermediate rocks present some of the main chemical diagnostic features of adakites, in which the metandesites and metatonalites are comparable to high-SiO2 adakites, and the metadiorites, characterized by very high MgO, Cr and Ni contents, are comparable to low-SiO2 adakites or high-Mg andesites. Metavolcanic and metaplutonic rocks show two main periods of magmatic crystallization ages with juvenile and slightly crustal contaminated rocks. The first occurred at 2.96?2.92 Ga with positive ?Nd (t) values of +2.16 to +2.77, while the second formed at 2.8 Ga with slightly negative ?Nd (t) value of 0.15. The volcanic and plutonic protoliths of the two greenstone belts were formed in an intraoceanic forearc-arc-back-arc system. The initial stage corresponds to ultramafic lava eruption in the forearc region of a proto-island arc, at 2.96 Ga. The evolution of the island arc and subduction progression led to oceanic slab-melting and generation of adakites. At 2.92 Ga, the adakitic melt was totally consumed by peridotite mantle and the subsequent melting of these hybridized mantle wedge generated high-Mg andesites that lodged in the crust as dioritic intrusions with high MgO, Cr and Ni contents. The late-stage corresponds to a continental arc formation at 2.8 Ga, marked by tonalitic magmatism and amalgamation with other island arcs and continental arcs of the TTG complexes of the Archean- Paleoproterozoic Terrane of Goi?s

Entangled-Photon Generation from Parametric Down-Conversion in Media with Inhomogeneous Nonlinearity

We develop and experimentally verify a theory of Type-II spontaneous parametric down-conversion (SPDC) in media with inhomogeneous distributions of second-order nonlinearity. As a special case, we explore interference effects from SPDC generated in a cascade of two bulk crystals separated by an air gap. The polarization quantum-interference pattern is found to vary strongly with the spacing between the two crystals. This is found to be a cooperative effect due to two mechanisms: the chromatic dispersion of the medium separating the crystals and spatiotemporal effects which arise from the inclusion of transverse wave vectors. These effects provide two concomitant avenues for controlling the quantum state generated in SPDC. We expect these results to be of interest for the development of quantum technologies and the generation of SPDC in periodically varying nonlinear materials.Comment: submitted to Physical Review

Convergence and Gauge Dependence Properties of the Resummed One-loop Quark-Quark Scattering Amplitude in Perturbative QCD

The one-loop QCD effective charge $\alpha_s^{eff}$ for quark-quark scattering is derived by diagrammatic resummation of the one-loop amplitude using an arbitary covariant gauge. Except for the particular choice of gauge parameter $\xi = -3$, $\alpha_s^{eff}$ is found to {\it increase} with increasing physical scale, $Q$, as $\ln Q$ or $\ln^2 Q$. For $\xi = -3$, $\alpha_s^{eff}$ decreases with increasing $Q$ and satisfies a renormalisation group equation. Also, except for the case $\xi = 19/9$, convergence radii of geometric series are found to impose upper limits on $Q$.Comment: 28 pages, 5 tables, 5 figures. v3 The one-loop amplitudes in Section 2 are recalculated using dimensional regularisation, and several errors in the on-shell calculation of Reference[1] are pointed out. v4 one figure removed one added. Three tables and new text in Section 5 added. Published versio

PIP5KIβ Selectively Modulates Apical Endocytosis in Polarized Renal Epithelial Cells

Localized synthesis of phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] at clathrin coated pits (CCPs) is crucial for the recruitment of adaptors and other components of the internalization machinery, as well as for regulating actin dynamics during endocytosis. PtdIns(4,5)P2 is synthesized from phosphatidylinositol 4-phosphate by any of three phosphatidylinositol 5-kinase type I (PIP5KI) isoforms (α, β or γ). PIP5KIβ localizes almost exclusively to the apical surface in polarized mouse cortical collecting duct cells, whereas the other isoforms have a less polarized membrane distribution. We therefore investigated the role of PIP5KI isoforms in endocytosis at the apical and basolateral domains. Endocytosis at the apical surface is known to occur more slowly than at the basolateral surface. Apical endocytosis was selectively stimulated by overexpression of PIP5KIβ whereas the other isoforms had no effect on either apical or basolateral internalization. We found no difference in the affinity for PtdIns(4,5)P2-containing liposomes of the PtdIns(4,5)P2 binding domains of epsin and Dab2, consistent with a generic effect of elevated PtdIns(4,5)P2 on apical endocytosis. Additionally, using apical total internal reflection fluorescence imaging and electron microscopy we found that cells overexpressing PIP5KIβ have fewer apical CCPs but more internalized coated structures than control cells, consistent with enhanced maturation of apical CCPs. Together, our results suggest that synthesis of PtdIns(4,5)P2 mediated by PIP5KIβ is rate limiting for apical but not basolateral endocytosis in polarized kidney cells. PtdIns(4,5)P2 may be required to overcome specific structural constraints that limit the efficiency of apical endocytosis. © 2013 Szalinski et al