Les ostracodes des « Couches Rouges » du synclinal d’Aït Attab, Haut Atlas Central, Maroc : systématique, biostratigraphie, paléoécologie, paléobiogéographie

Ostracode assemblages, collected in the continental “Red Beds” of the Central High Atlas, Morocco, consist of 35 species, belonging to 17 genera, four of which are new and described herein. They allow to assign the lower member of the Iouaridène formation to the Upper Jurassic (?)-Upper Hauterivian and the Jbel Sidal formation to the Upper Hauterivian-Lower Aptian. Ostracode assemblages characterize lacustrine (freshwater) and lagoonal (oligo to mesohaline) environments. On the basis of limnic and lagoonal species, faunal connections are proposed for the Barremian-Aptian between Morocco and the Iberian Peninsula.     

Ostracodes limniques de la Formation d'Irbzer, Crétacé terminal du Moyen-Atlas, Maroc : taxonomie, biostratigraphie, paléoécologie, paléobiogéographie

An association of limnic ostracodes has been discovered in the upper part of the Irbzer Formation, of Maastrichtian age, in the Moroccan Middle-Atlas. A new species is described, Gomphocythere achloujensis nov. sp. Paracandona occitanica, which is very common in terminal Cretaceous non-marine deposits of southern Europe (France, Spain), is found for the first time on the south Tethyan margin.     

Effects of the Oral Administration of K<Subscript>2</Subscript>Cr<Subscript>2</Subscript>O<Subscript>7</Subscript> and Na<Subscript>2</Subscript>SeO<Subscript>3</Subscript> on Ca,Mg, Mn,Fe, Cu,and Zn Contents in the Heart,Liver, Spleen,and Kidney of Chickens

This study aimed to investigate the effects of selenium on the ion profiles in the heart, liver, spleen, and kidney through the oral administration of hexavalent chromium. Approximately 22.14 mg/kg b.w. K₂Cr₂O₇ was added to water to establish a chronic poisoning model. Different selenium levels (0.00, 0.31, 0.63, 1.25, 2.50, and 5.00 mg Na₂SeO₃/kg b.w.) around the safe dose were administered to the experimental group model. Ca, Mg, Mn, Fe, Cu, and Zn were detected in the organs through flame atomic absorption spectrometry after these organs were exposed to K₂Cr₂O₇ and Na₂SeO₃ for 14, 28, and 42 days. Results showed that these elements exhibited various changes. Ca contents declined in the heart, liver, and spleen. Ca contents also decreased on the 28th day and increased on the 42nd day in the kidney. Mn contents declined in the heart and spleen but increased in the kidney. Mn contents also decreased on the 28th day and increased on the 42nd day in the liver. Cu contents declined in the heart and spleen. Cu contents increased on the 28th day and decreased on the 42nd day in the liver and kidney. Zn contents declined in the heart and spleen. Zn contents increased on the 28th day and decreased on the 42nd day in the liver and kidney. Fe contents decreased in the heart and liver. Fe contents increased on the 28th day and decreased on the 42nd day in the spleen and kidney. Mg contents did not significantly change in these organs. Appropriate selenium contents enhanced Mn and Zn contents, which were declined by chromium. Conversely, appropriate selenium contents reduced Ca, Fe, and Cu contents, which were increased by chromium. In conclusion, the exposure of chickens to K₂Cr₂O₇ induced changes in different trace elements, and Na₂SeO₃ supplementation could alleviate this condition.     

Blood‐Capillary‐Inspired,Free‐Standing,Flexible, and Low‐Cost Super‐Hydrophobic N‐CNTs@SS Cathodes for High‐Capacity,High‐Rate,and Stable Li‐Air Batteries

With the rising demand for flexible and wearable electronic devices, flexible power sources with high energy densities are required to provide a sustainable energy supply. Theoretically, rechargeable, flexible Li‐O₂/air batteries can provide extremely high specific energy densities; however, the high costs, complex synthetic methods, and inferior mechanical properties of the available flexible cathodes severely limit their practical applications. Herein, inspired by the structure of human blood capillary tissue, this study demonstrates for the first time the in situ growth of interpenetrative hierarchical N‐doped carbon nanotubes on the surface of stainless‐steel mesh (N‐CNTs@SS) for the fabrication of a self‐supporting, flexible electrode with excellent physicochemical properties via a facile and scalable one‐step strategy. Benefitting from the synergistic effects of the high electronic conductivity and stable 3D interconnected conductive network structure, the Li‐O₂ batteries obtained with the N‐CNTs@SS cathode exhibit superior electrochemical performance, including a high specific capacity (9299 mA h g^?1 at 500 mA g^?1), an excellent rate capability, and an exceptional cycle stability (up to 232 cycles). Furthermore, as‐fabricated flexible Li‐air batteries containing the as‐prepared flexible super‐hydrophobic cathode show excellent mechanical properties, stable electrochemical performance, and superior H₂O resistibility, which enhance their potential to power flexible and wearable electronic devices.     

Ndst1, a heparan sulfate modification enzyme, regulates neuroectodermal patterning by enhancing Wnt signaling in Xenopus

Neural tissue is derived from three precursor regions: neural plate, neural crest, and preplacodal ectoderm. These regions are determined by morphogen-mediated signaling. Morphogen distribution is generally regulated by binding to an extracellular matrix component, heparan sulfate (HS) proteoglycan. HS is modified by many enzymes, such as N-deacetyl sulfotransferase 1 (Ndst1), which is highly expressed in early development. However, functions of HS modifications in ectodermal patterning are largely unknown. In this study, we analyzed the role of Ndst1 using Xenopus embryos. We found that ndst1 was expressed in anterior neural plate and the trigeminal region at the neurula stage. ndst1 overexpression expanded the neural crest (NC) region, whereas translational inhibition reduced not only the trigeminal region, but also the adjacent NC region, especially the anterior part. At a later stage, ndst1 knocked-down embryos showed defects in cranial ganglion formation. We also found that Ndst1 activates Wnt signaling pathway at the neurula stage. Taken together, our results suggest that N-sulfonated HS accumulates Wnt ligand and activates Wnt signaling in ndst1-expressing cells, but that it inhibits signaling in non-ndst1-expressing cells, leading to proper neuroectodermal patterning.