Analysis of the cell cycle of neural progenitors in the developing ferret neocortex

Description of the cell cycle features of neural progenitors during late stages of neurogenesis in a gyrencephalic mammal, the ferret

Bentonite powder XRD quantitative analysis using Rietveld refinement: Revisiting and updating bulk semiquantitative mineralogical compositions

Bentonite is a claystone formed by a complex mineralogical mixture, composed of mont-morillonite, illite, and accessory minerals like quartz, cristobalite, feldspars, carbonates, and minor amounts of iron oxy-hydroxides. Bentonite presents complexity at various scales: (1): a single mineral may present different chemical composition within the same quarry (e.g., feldspars solid solu-tions); (2): montmorillonite presents variability in the cation-exchange distribution while illite may be presented as mixed-layer with smectite sheets; and (3): hardness and crystal size are larger in accessory minerals than in clay minerals, preventing uniform grinding of bentonite. The FEBEX bentonite used is originally from Almería (Spain), and it is a predominantly calcium, magnesium, and sodium bentonite. This Spanish FEBEX bentonite has been hydrothermally altered at laboratory scale for 7–14 years. A thermal gradient was generated by heating a disk of pressed iron powder, simulating the metal waste canister, in contact with the compacted bentonite sample. Hydration was forced from the opposite direction. XRD recorded patterns were very similar. In order to min-imize the bias of XRD semi-quantitative determination methods, Rietveld refinement was per-formed using BGMN software and different structural models. Confidence in the quantification of the main phases allows us to convincingly detect other subtle changes such as the presence of calcite in the hydration front, right at the interface between the saturated and unsaturated bentonite, or the presence of goethite, and not hematite, in the saturated bentonite, near the source of hydration. Smectite component was 72 ± 3% and the refinement was consistent with the presence of ~10% illite, comparable with previous characterization

Desarrollo de una herramienta para la evaluación de los examen tipo test y sus aplicaciones en la mejora de la calidad y en los criterios de evaluación de estos exámenes

Depto. de Radiología, Rehabilitación y FisioterapiaFac. de MedicinaFALSEsubmitte

Analysis of the cell cycle of neural progenitors in the developing ferret neocortex

Description of the cell cycle features of neural progenitors during late stages of neurogenesis in a gyrencephalic mammal, the ferret

Analysis of the cell cycle of neural progenitors in the developing ferret neocortex

Description of the cell cycle features of neural progenitors during late stages of neurogenesis in a gyrencephalic mammal, the ferret

S‐phase duration is the main target of cell cycle regulation in neural progenitors of developing ferret neocortex

ABSTRACT The evolutionary expansion of the neocortex primarily reflects increases in abundance and proliferative capacity of cortical progenitors and in the length of the neurogenic period during development. Cell cycle parameters of neocortical progenitors are an important determinant of cortical development. The ferret (Mustela putorius furo), a gyrencephalic mammal, has gained increasing importance as a model for studying corticogenesis. Here, we have studied the abundance, proliferation, and cell cycle parameters of different neural progenitor types, defined by their differential expression of the transcription factors Pax6 and Tbr2, in the various germinal zones of developing ferret neocortex. We focused our analyses on postnatal day 1, a late stage of cortical neurogenesis when upper‐layer neurons are produced. Based on cumulative 5‐ethynyl‐2′‐deoxyuridine (EdU) labeling as well as Ki67 and proliferating cell nuclear antigen (PCNA) immunofluorescence, we determined the duration of the various cell cycle phases of the different neocortical progenitor subpopulations. Ferret neocortical progenitors were found to exhibit longer cell cycles than those of rodents and little variation in the duration of G1 among distinct progenitor types, also in contrast to rodents. Remarkably, the main difference in cell cycle parameters among the various progenitor types was the duration of S‐phase, which became shorter as progenitors progressively changed transcription factor expression from patterns characteristic of self‐renewal to those of neuron production. Hence, S‐phase duration emerges as major target of cell cycle regulation in cortical progenitors of this gyrencephalic mammal. J. Comp. Neurol. 524:456–470, 2016. © 2015 The Authors The Journal of Comparative Neurology Published by Wiley Periodicals, Inc

Morphological, demographic and genetic traces of Upper Palaeolithic human impact on limpet assemblages in North Iberia

This study was supported by the Spanish project MICINN CGL2009-08279 and the Regional Project FICYT IB09-0023. P.T. holds a PCTI grant (reference BP08-077).Human activities have an impact on extant biotic communities, and may have had just as important an impact in the past. We assess human impact on limpet assemblages during the Upper Palaeolithic in Asturias (north-west Spain). The intensely exploited genus Patella exhibited a marked size decrease and a change in species assemblage composition, substituting the larger species P. vulgata for the smaller P. depressa. The present Patella assemblages in the upper tidal level exhibit the same pattern as those of the Epipalaeolithic (approx. 12 000 to 6000 years before the present). Although climate change may have contributed to such species replacement, spatial differences between close areas with different densities of Palaeolithic human settlements indicate unequivocal human impact. Present Patella species sampled from the region exhibit genetic signatures of past bottlenecks in mitochondrial DNA, which also indicate recent demographic expansion, suggesting that old impacts have been sufficiently important to leave genetic traces in current populations.Depto. de Genética, Fisiología y MicrobiologíaFac. de Ciencias BiológicasTRUEpu