Lower Cretaceous (Hauterivian-Albian) ammonite biostratigraphy in the Maestrat Basin (E Spain)

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Geology of the Falcón Basin (NW Venezuela)

This paper presents a geological map and cross-section of the Falcón Basin based both on published and unpublished work and on new data collected in the northern and southern basin margins. The geological map covers an area of 4600 km2 at 1:100,000 scale. The cross- section is oriented NNW-SSE, traversing perpendicular to the main structures. In general, the structure of the study area results from the inversion of a graben (Oligocene-early Miocene back-arc basin), that started in the middle Miocene due to the convergence between the Caribbean and South American plates. The map, the cross-section and the observations made in the field have been used to generate a tectonostratigraphic reconstruction of the Falcón Basin. The Oligocene-early Miocene sedimentary succession mapped and described is relevant to the hydrocarbon exploration in the Caribbean and in the Gulf of Venezuela, where new hydrocarbon resources have recently been discovered (i.e. Perla gas field)

DYRK1A promotes dopaminergic neuron survival in the developing brain and in a mouse model of Parkinson's disease

In the brain, programmed cell death (PCD) serves to adjust the numbers of the different types of neurons during development, and its pathological reactivation in the adult leads to neurodegeneration. Dual-specificity tyrosine-(Y)-phosphorylation regulated kinase 1A (DYRK1A) is a pleiotropic kinase involved in neural proliferation and cell death, and its role during brain growth is evolutionarily conserved. Human DYRK1A lies in the Down syndrome critical region on chromosome 21, and heterozygous mutations in the gene cause microcephaly and neurological dysfunction. The mouse model for DYRK1A haploinsufficiency (the Dyrk1a +/− mouse) presents neuronal deficits in specific regions of the adult brain, including the substantia nigra (SN), although the mechanisms underlying these pathogenic effects remain unclear. Here we study the effect of DYRK1A copy number variation on dopaminergic cell homeostasis. We show that mesencephalic DA (mDA) neurons are generated in the embryo at normal rates in the Dyrk1a haploinsufficient model and in a model (the mBACtg Dyrk1a mouse) that carries three copies of Dyrk1a. We also show that the number of mDA cells diminishes in postnatal Dyrk1a +/− mice and increases in mBACtg Dyrk1a mice due to an abnormal activity of the mitochondrial caspase9 (Casp9)-dependent apoptotic pathway during the main wave of PCD that affects these neurons. In addition, we show that the cell death induced by 1-methyl-4-phenyl-1,2,3,6 tetrahydropyridine (MPTP), a toxin that activates Casp9-dependent apoptosis in mDA neurons, is attenuated in adult mBACtg Dyrk1a mice, leading to an increased survival of SN DA neurons 21 days after MPTP intoxication. Finally, we present data indicating that Dyrk1a phosphorylation of Casp9 at the Thr125 residue is the mechanism by which this kinase hinders both physiological and pathological PCD in mDA neurons. These data provide new insight into the mechanisms that control cell death in brain DA neurons and they show that deregulation of developmental apoptosis may contribute to the phenotype of patients with imbalanced DYRK1A gene dosage

Suplementación del medio de congelación de semen de conejo con quercertina

Al ser los espermatozoides células muy sensibles al daño oxidativo, el aumento de la producción de las especies reactivas de oxígeno (ERO) que se produce durante las etapas de congelación y descongelación provoca un efecto perjudicial sobre los mismos. El uso de antioxidantes en los medios de congelación puede prevenir el estrés oxidativo y mejorar las características seminales post-congelación y con ello la capacidad fecundante del semen. Existe un creciente interés en suplementar los medios de congelación de semen de conejo con sustancias con actividad antioxidante, ya que puede se ha observado que pueden mejorar los parámetros de calidad seminal (Nishijima et al., 2021). La quercertina, polifenol de origen vegetal, es un flavonoide que presenta mayor actividad antioxidante y menor toxicidad que los antioxidantes sintéticos (Silva et al., 2012; Zhong y Zhou, 2013). La quercertina es un potente antioxidante, utilizado en la congelación de semen de diferentes especies (bovino, ovino, por cino, equino y humano), y es capaz de reducir el daño que el aumento de ERO produce en los espermatozoides. En conejo, la utilización de quercertina en congelación de semen no ha sido estudiada hasta el momento. Por ello, el objetivo del presente trabajo es evaluar el efecto de la adición de quercertina al medio de congelación sobre diferentes parámetros seminales en conejo

Adición de análogos de antioxidantes presentes en el plasma seminal al medio de congelación de semen de conejo

En el plasma seminal, para mantener una función espermática óptima, coexisten en equilibrio tanto especies reactivas al oxígeno (ERO) como antioxidantes. No obstante, durante la congelación del semen, la excesiva generación de ERO puede provocar un desequilibrio del mecanismo de protección y alterar los lípidos y/o proteínas de las membranas de los espermatozoides (Sanocka y Kurpisz, 2004). La utilización de antioxidantes en los medios de congelación puede prevenir el estrés oxidativo y mejorar las características seminales (Nishijima et al. 2021). Entre los principales antioxidantes presentes en el semen podemos encontrar la enzima superóxido dismutasa (SOD) y la vitamina E (Kowalczyk, 2022). La SOD previene la formación de nuevos radicales libres, mientras que la vitamina E actúa capturando los radicales libres que se forman para evitar las reacciones en cadena posteriores El objetivo del presente trabajo es evaluar el efecto de la adición de análogos sintéticos de la vitamina E y la SOD en el medio de congelación de semen de conejo, analizando diferentes parámetros seminales in vitro y su capacidad fecundante in vivo

Body Shape and Life Style of the Extinct Balearic Dormouse Hypnomys (Rodentia, Gliridae): New Evidence from the Study of Associated Skeletons

Hypnomys is a genus of Gliridae (Rodentia) that occurred in the Balearic Islands until Late Holocene. Recent finding of a complete skeleton of the chronospecies H. morpheus (Late Pleistocene-Early Holocene) and two articulated skeletons of H. cf. onicensis (Late Pliocene) allowed the inference of body size and the calculation of several postcranial indexes. We also performed a Factorial Discriminant Analysis (FDA) in order to evaluate locomotory behaviour and body shape of the taxa. Using allometric models based on skull and tooth measurements, we calculated a body weight between 173 and 284 g for H. morpheus, and direct measurements of articulated skeletons yielded a Head and Body Length (HBL) of 179 mm and a Total Body Length of 295 mm for this species. In addition to the generally higher robustness of postcranial bones already recorded by previous authors, H. morpheus, similar to Canariomys tamarani, another extinct island species, displayed elongated zygopodium bones of the limbs and a wider distal humerus and femur than in an extant related taxon, Eliomys quercinus. Indexes indicated that Hypnomys was more terrestrial and had greater fossorial abilities than E. quercinus. This was also corroborated by a Discriminant Analysis, although no clear additional inference of locomotory abilities could be calculated

Geological, geochemical and mineralogical characteristics of REE-bearing Las Mercedes bauxite deposit, Dominican Republic

Bauxite deposits, traditionally the main source of 'aluminum, have been recently targeted for their remarkable contents in rare earth elements (REE). With Sigma REE (lanthanoids + Sc + Y) concentrations systematically higher than similar to 1400 ppm (ay. = 1530 ppm), the Las Mercedes karstic bauxites in the Dominican Republic rank as one of the REE-richest deposits of its style.The bauxitic ore in the Las Mercedes deposit is mostly unlithified and has a homogeneous-massive lithostructure, with only local cross-stratification and graded bedding. The dominant arenaceous and round-grained texture is composed of bauxite particles and subordinate ooids, pisoids and carbonate clasts. Mineralogically, the bauxite ore is composed mostly of gibbsite and lesser amounts of kaolinite, hematite, boehmite, anatase, goethite, chromian spinel and zircon. Identified REE-minerals include cerianite and monazite-Ce, whose composition accounts for the steady enrichment in light-relative to medium-and heavy-REE of the studied bauxites.Considering the paleo-geomorphology of the study area, we propose that bauxites in the Las Mercedes deposit are the product of the erosion and deposition of lithified bauxites located at higher elevations in the Bahoruco ranges. Based on the available data, we suggest a mixed lithological source for the bauxite deposits at the district scale: bedrock carbonates and an igneous source of likely mafic composition. (C) 2017 Elsevier B.V. All rights reserved

Lower Cretaceous (Hauterivian-Albian) ammonite biostratigraphy in the Maestrat Basin (E Spain)

A review of the stratigraphic distribution of ammonoid species in the Lower Cretaceous (Hauterivian-Albian) of the Maestrat Basin (E Spain) was carried out. The specimens were mainly collected in the field by us and are stored in university or museum collections. Speci­mens from private collections and figured in the literature were also studied. We recognized 73 species that are distributed, in accordance with the latest version of the standard Mediterranean ammonite zonation for the Lower Cretaceous, in 14 ammonite zones: Acanthodiscus radiatus, Crioceratites loryi, Lyticoceras nodosoplicatum (Lower Hauterivian); Pseudothurmannia ohmi (Upper Hauterivian); Imerites giraudi (Upper Barremian); Deshayesites oglanlensis, Deshayesites forbesi, Deshayesites deshayesi, Dufrenoyia furcata (Lower Aptian); Epicheloniceras martini, Parahoplites melchioris, Acanthohoplites nolani (Upper Aptian); Leymeriella tardefurcata and Douvilleiceras mammillatum (Lower Albian). The recognition of these biozones allows a precise age calibration of the Maestrat Basin’s lithostatigraphic units that contain ammonoids as well as an associated indirect age calibration of the formations without ammonoids. Consequently, this report provides an updated, comprehensive and precise biostratigraphic framework, which aims to become a reference for the analysis of the Lower Cretaceous strata of the Maestrat Basin. The results are also relevant for the analysis of coeval ammonite-bearing sedimentary successions found in other Tethyan basins.En este trabajo se ha realizado una revisión detallada de la distribución estratigráfica de las especies de ammonoideos del Cretácico infe­rior de la Cuenca del Maestrazgo (Este de España). Los ejemplares recolectados, principalmente por los autores, han sido depositados en co­lecciones universitarias y museísticas. Además hemos estudiado los ejemplares de colecciones privadas y figurados en la literatura. Hemos reconocido 73 especies que se distribuyen, siguiendo la última versión de la biozonación de ammonites mediterránea estándar del Cretácico inferior, en 14 zonas de ammonoideos: Acanthodiscus radiatus, Crioceratites loryi, Lyticoceras nodosoplicatum (Hauteriviense inferior); Pseudothurmannia ohmi (Hauteriviense superior); Imerites giraudi (Barremiense superior); Deshayesites oglanlensis, Deshayesites forbesi, Deshayesites deshayesi, Dufrenoyia furcata (Aptiense inferior); Epicheloniceras martini, Parahoplites melchioris, Acanthohoplites nolani (Aptiense superior); Leymeriella tardefurcata y Douvilleiceras mammillatum (Albiense inferior). El reconocimiento de estas biozonas permite precisar la edad de las unidades litoestratigráficas que contienen ammonites y también una calibración indirecta de las formaciones que no contienen ammonites. En consecuencia este trabajo proporciona un marco bioestratigráfico actualizado, exhaustivo y preciso que pretende ser una referencia para el análisis estratigráfico del Cretácico inferior de la Cuenca del Maestrazgo. Los resultados obtenidos son también relevantes para el análisis de las sucesiones sedimentarias coetáneas con ammonites existentes en otras cuencas de Tetis