Catálogo de publicaciones - revistas

<jats:p>The geological units on the floor of Jezero crater, Mars, are part of a wider regional stratigraphy of olivine-rich rocks, which extends well beyond the crater. We investigate the petrology of olivine and carbonate-bearing rocks of the Séítah formation in the floor of Jezero. Using multispectral images and x-ray fluorescence data, acquired by the Perseverance rover, we performed a petrographic analysis of the Bastide and Brac outcrops within this unit. We find that these outcrops are composed of igneous rock, moderately altered by aqueous fluid. The igneous rocks are mainly made of coarse-grained olivine, similar to some Martian meteorites. We interpret them as an olivine cumulate, formed by settling and enrichment of olivine through multi-stage cooling of a thick magma body.</jats:p>

<jats:p>Lysosomes coordinate cellular metabolism and growth upon sensing of essential nutrients, including cholesterol. Through bioinformatic analysis of lysosomal proteomes, we identified LYsosomal CHOlesterol Signaling (LYCHOS, previously annotated as G-protein coupled receptor 155), a multidomain transmembrane protein that enables cholesterol-dependent activation of the master growth regulator, the protein kinase mechanistic Target of Rapamycin Complex 1 (mTORC1). Cholesterol bound to the N-terminal permease-like region of LYCHOS, and mutating this site impaired mTORC1 activation. At high cholesterol concentrations, LYCHOS bound to the GATOR1 complex, a GTPase-activating protein for the Rag guanosine triphosphatases, through a conserved cytoplasm-facing loop. By sequestering GATOR1, LYCHOS promotes cholesterol- and Rag-dependent recruitment of mTORC1 to lysosomes. Thus, LYCHOS functions in a lysosomal pathway for cholesterol sensing, and couples cholesterol concentrations to mTORC1-dependent anabolic signaling.</jats:p>

<jats:p> The Perseverance rover landed in Jezero crater, Mars, to investigate ancient lake and river deposits. We report observations of the crater floor, below the crater’s sedimentary delta, finding the floor consists of igneous rocks altered by water. The lowest exposed unit, informally named Séítah, is a coarsely crystalline olivine-rich rock, which accumulated at the base of a magma body. Fe-Mg carbonates along grain boundaries indicate reactions with CO <jats:sub>2</jats:sub> -rich water, under water-poor conditions. Overlying Séítah is a unit informally named Máaz, which we interpret as lava flows or the chemical complement to Séítah in a layered igneous body. Voids in these rocks contain sulfates and perchlorates, likely introduced by later near-surface brine evaporation. Core samples of these rocks were stored aboard Perseverance for potential return to Earth. </jats:p>

<jats:p>The Type III-E RNA-targeting effector complex (gRAMP/Cas7-11) is associated with a caspase-like protein (TPR-CHAT/Csx29) to form Craspase (CRISPR-guided caspase). Here we use cryo-electron microscopy snapshots of Craspase to explain its target RNA cleavage and protease activation mechanisms. Target-guide pairing extending into the 5′ region of the guide RNA displaces a gating loop in gRAMP, which triggers an extensive conformational relay that allosterically aligns the protease catalytic dyad and opens an amino acid sidechain-binding pocket. We further define Csx30 as the endogenous protein substrate that is site-specifically proteolyzed by RNA-activated Craspase. This protease activity is switched off by target RNA cleavage by gRAMP, and is not activated by RNA targets containing a matching protospacer flanking sequence. We thus conclude that Craspase is a target RNA-activated protease with self-regulatory capacity.</jats:p>

<jats:p> The granular dorsolateral prefrontal cortex (dlPFC) is an evolutionary specialization of primates that is centrally involved in cognition. Here, we assessed over 600,000 single-nucleus transcriptomes from adult human, chimpanzee, macaque, and marmoset dlPFC. While most transcriptomically-defined cell subtypes are conserved, we detected several only in some species and substantial species-specific molecular differences across homologous neuronal, glial and non-neural subtypes. The latter are exemplified by human-specific switching between expression of the neuropeptide somatostatin (SST) and tyrosine hydroxylase (TH), the rate-limiting enzyme in dopamine production, in certain interneurons, and also by expression of the neuropsychiatric risk gene <jats:italic>FOXP2</jats:italic> , which is human-specific in microglia and primate-specific in layer-4 granular neurons. We generated a comprehensive survey of dlPFC cellular repertoire and its shared and divergent features in anthropoid primates. </jats:p>

<jats:p>By sequencing 727 ancient individuals from the Southern Arc (Anatolia and its neighbors in Southeastern Europe and West Asia) over 10,000 years, we contextualize its Chalcolithic period and Bronze Age (about 5000 to 1000 BCE), when extensive gene flow entangled it with the Eurasian steppe. Two streams of migration transmitted Caucasus and Anatolian/Levantine ancestry northward, and the Yamnaya pastoralists, formed on the steppe, then spread southward into the Balkans and across the Caucasus into Armenia, where they left numerous patrilineal descendants. Anatolia was transformed by intra–West Asian gene flow, with negligible impact of the later Yamnaya migrations. This contrasts with all other regions where Indo-European languages were spoken, suggesting that the homeland of the Indo-Anatolian language family was in West Asia, with only secondary dispersals of non-Anatolian Indo-Europeans from the steppe.</jats:p>

<jats:p>Earlier this year, when I was confirmed as the new commissioner of the US Food and Drug Administration (FDA), the world faced ongoing public health issues related to the pandemic and war in Ukraine, among other challenges. Most notably, the US is experiencing a flattening or decline in life expectancy compared with other high-income countries. As part of a wider effort to reverse this decline, relationships between FDA and the biomedical ecosystem should be reimagined to facilitate more effective translation of science into successful health interventions.</jats:p>

<jats:p>Studies seek clues to origins of farming, early languages</jats:p>