Long non-coding RNAs: spatial amplifiers that control nuclear structure and gene expression

Over the past decade, it has become clear that mammalian genomes encode thousands of long non-coding RNAs (lncRNAs), many of which are now implicated in diverse biological processes. Recent work studying the molecular mechanisms of several key examples — including Xist, which orchestrates X chromosome inactivation — has provided new insights into how lncRNAs can control cellular functions by acting in the nucleus. Here we discuss emerging mechanistic insights into how lncRNAs can regulate gene expression by coordinating regulatory proteins, localizing to target loci and shaping three-dimensional (3D) nuclear organization. We explore these principles to highlight biological challenges in gene regulation, in which lncRNAs are well-suited to perform roles that cannot be carried out by DNA elements or protein regulators alone, such as acting as spatial amplifiers of regulatory signals in the nucleus

A Review of the Current State and Recent Changes of the Andean Cryosphere

International audienc

Diversification of Asaphellus Callaway, 1877 (Asaphidae: Trilobita) during the Tremadocian in South West Gondwana (Cordillera Oriental, Argentina)

Asaphellus Callaway, 1877 is the earliest widespread genus of the family Asaphidae Burmeister, 1843, and although its systematics bears several problematic issues, an input to overcome these difficulties has been attempted. Our main focus is a group of strongly effaced Asaphellus species from the Cordillera Oriental (NW Argentina), including new material from the Santa Rosita Formation (Furongian- Tremadocian), mainly belonging to Alfarcito and Rupasca members (Quebrada del Arenal, Perchel, Jujuy Province). Asaphellus is reconsidered herein in order to restrict some features and discuss others not taken in account before. Moreover, several problematic Argentinean species are revised. The poorly known, but extensively cited, A. catamarcensis Kobayashi, 1935 is assessed here upon the type series in order to clarify its taxonomy and previous assignments. A reappraisal of A. stenorhachis (Harrington, 1938), another enduring problematic taxon, is proposed. Besides, A. isabelae n. sp., a unique species within the genus mainly due to its extreme effacement is defined herein. Other species left in open nomenclature are also described. Regarding local random occurrences in the Furongian, the genus radiated locally from the early Tremadocian (Tr1) onwards, however, taxonomic diversification was not mirrored by the abundance of Asaphellus in local communities. From the middle Tremadocian (Tr2) this diversification is associated with an increase in abundance, and even dominance of the taxon in numerous assemblages, further expanding its environmental range into shallower settings. The increase of Asaphellus diversity (Tr1- early Tr2) is decoupled from the records of local increase in Asaphidae diversity since the late Tremadocian (Tr3) and Floian, underscoring the complex pattern of diversification at different taxonomic levels.Fil: Meroi Arcerito, Facundo René. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Waisfeld, Beatriz Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Balseiro, Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; Argentin