New records of Orchids from Morocco

The exploration of the Rif Valley (Morocco) during 2010 revealed the presence of some new taxa and records from Morocco. The new taxa are: Orchis langei subsp. magrebensis and Ophrys neglecta var. riphaea. Ophrys neglecta var. neglecta and Ophrys numida have been detected for the first time in Morocco

Hydrogen sulphide as a guard cell network regulator

Hydrogen sulphide (H2S) is an endogenously produced gasotransmitter that has rapidly emerged as an active signalling component of several plant processes, stomatal movement regulation among them. The guard cells (GCs), pairs of cells that neighbour the stomatal pores, transduce endogenous and environmental signals, through signalling network, to control stomatal pore size. In this complex network, which has become a model system for plant signalling, few highly connected components form a core that links most of the pathways. The evidence summarized in this insight, on the interplay between H2S and different key components of the GC networks, points towards H2S as a regulator of the GC core signalling pathway.Fil: Pantaleno, Rosario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Scuffi, Denise. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Garcia-Mata, Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; Argentin

Diferencias en habilidades y conducta entre grupos de preescolares de alto y bajo rendimiento escolar

El objetivo ha sido analizar la relación entre variables psicológicas y rendimiento escolar en niños preescolares. Se ha seleccionado un conjunto de variables cognitivas y conductuales, que según la bibliografía más actualizada se relacionan con el aprendizaje escolar, con el fin de identificar los factores que parecen influir en el rendimiento educativo en la etapa infantil. La meta final sería intentar prevenir problemas de rendimiento futuros mediante la identificación temprana de estas variables en los niños que parecen presentar bajo rendimiento. La muestra ha estado compuesta por 47 niños: 23 con alto rendimiento y 24 con bajo rendimiento. Se han utilizado medidas de inteligencia (K-BIT), potencial de aprendizaje (EHPAP) y metacognición. Los resultados muestran que los grupos difieren en el perfil de habilidades, en variables conductuales y en la utilización de estrategias metacognitivas. Sin embargo, todos presentan un potencial de aprendizaje similar

Calmodulin antagonizes amyloid-β peptides-mediated inhibition of brain plasma membrane Ca2+-ATPase

AbstractThe synaptosomal plasma membrane Ca2+-ATPase (PMCA) plays an essential role in regulating intracellular Ca2+ concentration in brain. We have recently found that PMCA is the only Ca2+ pump in brain which is inhibited by amyloid-β peptide (Aβ), a neurotoxic peptide implicated in the pathology of Alzheimer's disease (AD) [1], but the mechanism of inhibition is lacking. In the present study we have characterized the inhibition of PMCA by Aβ. Results from kinetic assays indicate that Aβ aggregates are more potent inhibitors of PMCA activity than monomers. The inhibitory effect of Aβ could be blocked by pretreating the purified protein with Ca2+-calmodulin, the main endogenous activator of PMCA, and the activity of truncated PMCA lacking the calmodulin binding domain was not affected by Aβ. Dot-overlay experiments indicated a physical association of Aβ with PMCA and also with calmodulin. Thus, calmodulin could protect PMCA from inhibition by Aβ by burying exposed sites on PMCA, making them inaccessible to Aβ, and also by direct binding to the peptide. These results suggest a protective role of calmodulin against neuronal Ca2+ dysregulation by PMCA inhibition induced by Aβ

Ontogeny of ATP hydrolysis and isoform expression of the Plasma Membrane Ca2+-ATPase in mouse brain.

Background: Plasma membrane Ca2+-ATPases (PMCAs) are high affinity Ca2+ transporters actively involved in intracellular Ca2+ homeostasis. Considering the critical role of Ca2+ signalling in neuronal development and plasticity, we have analyzed PMCA-mediated Ca2+-ATPase activity and PMCA-isoform content in membranes from mouse cortex, hippocampus and cerebellum during postnatal development. Results: PMCA activity was detected from birth, with a faster evolution in cortex than in hippocampus and cerebellum. Western blots revealed the presence of the four isoforms in all regions, with similar increase in their expression patterns as those seen for the activity profile. Immunohistochemistry assays in cortex and hippocampus showed co-expression of all isoforms in the neuropil associated with synapses and in the plasma membrane of pyramidal cells soma, while cerebellum showed a more isoform-specific distribution pattern in Purkinje cells. Conclusion: These results show an upregulation of PMCA activity and PMCA isoforms expression during brain development in mouse, with specific localizations mainly in cerebellum. Overall, our findings support a close relationship between the ontogeny of PMCA isoforms and specific requirements of Ca2+ during development of different brain areas.post-print2271 K

Developmental distribution of plasma membrane Ca2+-ATPase isoforms in chick cerebellum.

The plasma membrane Ca2+-ATPase (PMCA) is highly expressed in the nervous system, but little information is available about its implication in neuronal development. We have analyzed the expression and localization of different isoforms of PMCA in membrane vesicles and sections of chick cerebellum from embryonic day 10 to hatching. We found that the relative amount of each PMCA isoform and their spatiotemporal distribution in the cerebellum are directly linked to precise cellular types during the cerebellar maturation, even in a non-neural tissue as choroid plexus. Purkinje cells contain the highest diversity of PMCA isoforms of the cerebellar cortex since the moment of its morphogenesis. From embryonic day 15, the PMCA2 was highly expressed in the whole Purkinje cell, while PMCAs 1 and 3 had a more restricted distribution in the soma and dendritic branches, and these distributions were evolving according with cell maturation. Other cellular types seem to contain a specific combination of isoforms, but with a well-defined distribution pattern at late moments of development. Thus, PMCAs 1 and 3 were located in the soma of molecular layer interneurons, and only the PMCA2 was observed in granule cells at hatching. Furthermore, PMCA isoforms are also expressed in cellular compartments characterized by a high amount of synapses, suggesting a key role of these proteins in synaptogenesis and in the maturation of neuronal electrophysiological properties.post-print1698 K

Point of optimal kinematic error: Improvement of the instantaneous helical pivot method for locating centers of rotation

[EN] This paper proposes a variation of the instantaneous helical pivot technique for locating centers of rotation. The point of optimal kinematic error (POKE), which minimizes the velocity at the center of rotation, may be obtained by just adding a weighting factor equal to the square of angular velocity in Woltring's equation of the pivot of instantaneous helical axes (PIHA). Calculations are simplified with respect to the original method, since it is not necessary to make explicit calculations of the helical axis, and the effect of accidental errors is reduced. The improved performance of this method was validated by simulations based on a functional calibration task for the gleno-humeral joint center. Noisy data caused a systematic dislocation of the calculated center of rotation towards the center of the arm marker cluster. This error in PIHA could even exceed the effect of soft tissue artifacts associated to small and medium deformations, but it was successfully reduced by the POKE estimation.This work has been funded by the Spanish Government (Grants DPI2009-13830-C02-01, DPI2009-13830-CO2-02, DPI2010-20814-CO2-01, DPI2010-20814-CO2-02).De Rosario Martínez, H.; Page Del Pozo, AF.; Mata Amela, V. (2014). Point of optimal kinematic error: Improvement of the instantaneous helical pivot method for locating centers of rotation. Journal of Biomechanics. 47(7):1742-1747. doi:10.1016/j.jbiomech.2014.02.003S1742174747

Ontogeny of ATP hydrolysis and isoform expression of the Plasma Membrane Ca2+-ATPase in mouse brain

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