Cold giant planets evaporated by hot white dwarfs

Atmospheric escape from close-in Neptunes and hot Jupiters around Sun-like stars driven by extreme ultraviolet (EUV) irradiation plays an important role in the evolution of exoplanets and in shaping their ensemble properties. Intermediate and low mass stars are brightest at EUV wavelengths at the very end of their lives, after they have expelled their envelopes and evolved into hot white dwarfs. Yet the effect of the intense EUV irradiation of giant planets orbiting young white dwarfs has not been assessed. We show that the giant planets in the solar system will experience significant hydrodynamic escape caused by the EUV irradiation from the white dwarf left behind by the Sun. A fraction of the evaporated volatiles will be accreted by the solar white dwarf, resulting in detectable photospheric absorption lines. As a large number of the currently known extrasolar giant planets will survive the metamorphosis of their host stars into white dwarfs, observational signatures of accretion from evaporating planetary atmospheres are expected to be common. In fact, one-third of the known hot single white dwarfs show photospheric absorption lines of volatile elements, which we argue are indicative of ongoing accretion from evaporating planets. The fraction of volatile contaminated hot white dwarfs strongly decreases as they cool. We show that accretion from evaporating planetary atmospheres naturally explains this temperature dependence if more than 50% of hot white dwarfs still host giant planets

High pCO 2 levels affect metabolic rate, but not feeding behavior and fitness, of farmed giant mussel Choromytilus chorus

Indexación: Scopus.Acknowledgements. We thank Luisa Saavedra and Araceli Rodriguez-Romero for their help in the field and during laboratory activities. We also acknowledge Laura Ramajo for help with AT estimations. Emily Giles Neill provided valuable comments that greatly improved the manuscript. Special thanks are due to the reviewers and the editor for very constructive comments on the manuscript. This study was supported by the Millennium Nucleus Center for the Study of Multiple drivers on Marine Socio-Ecological Systems (MUSELS) funded by MINECON NC120086, PIA CONICYT ACT-172037 and FONDECYT grant nos. 1140938 and 1140092 to N.A.L. and M.A.L.Mar Ecol Prog Ser 454: 65−74 Findlay HS, Wood HL, Kendall MA, Spicer JI, Twitchett RJ, Widdicombe S (2009) Calcification, a physiological pro-cess to be considered in the context of the whole organ-ism. 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Estuaries Coasts 38: 1163−1177 Vargas CA, Lagos NA, Lardies MA, Duarte C and others (2017) Species-specific responses to ocean acidification should account for local adaptation and adaptive plasti-city. Nature Ecol Evol 1: 0084 Vargas CA, Cuevas LA, Silva N, Gonzalez HE, Pol-Holz D, Narvaez DA (2018) Influence of glacier melting and river discharges on the nutrient distribution and DIC recycling in the southern Chilean Patagonia. J Geophys Res Bio-geosci 123: 256−270 Velasco LA, Navarro JM (2003) Energetic balance of infau-nal (Mulinia edulis King, 1831) and epifaunal (Mytilus chilensis Hupé, 1854) bivalves in response to wide varia-tions in concentration and quality of seston. J Exp Mar Biol Ecol 296: 79−92 Vihtakari M, Hendriks IE, Holding J, Renaud PE, Duarte CM, Havenhand JN (2013) Effects of ocean acidification and warming on sperm activity and early life stages of the Mediterranean mussel (Mytilus galloprovincialis). Water 5: 1890−1915 Wang Y, Li L, Hu M, Lu W (2015) Physiological energetic of the thick shell mussel Mytilus coruscus exposed to sea-water acidification and thermal stress. Sci Total Environ 514: 261−272 White MM, McCorkle DC, Mullineaux LS, Cohen AL (2013)Benthic habitats such as intertidal areas, sandy or rocky shores, upwelling zones, and estuaries are characterized by variable environmental conditions. This high variability of environmental stressors such as temperature, salinity, and pH/pCO 2 levels have been shown to impose restrictions on organismal performance. The giant mussel Choromytilus chorus forms intertidal and subtidal mussel beds in estuarine zones associated with fjords occurring in southern Chile and is an important aquacultural resource in Patagonia. In this study, we estimated the sensitivity of physiological traits and energy balance of C. chorus juveniles exposed to 3 pCO 2 treatments (500, 750, and 1200 μatm) for 30 d. Results showed that in acidified, high pCO 2 conditions, C. chorus juveniles had increased metabolic rates; however, other physiological traits (clearance and ingestion rates, ammonia excretion, absorption efficiency, growth rate, biomass production, net calcification, and dissolution rates) were not affected. These results suggest that when subjected to acidification, the adaptive response of C. chorus triggers tradeoffs among physiological traits that favor sustained feeding and growth in order to combat increased metabolic stress. As has been reported for other marine organisms, chronic exposure to variable pH/pCO 2 in their native habitats, such as estuarine zones, could explain the differential acclimatization capacity of giant mussels to cope with the increase in pCO 2 . Additionally, the fact that the mussels did not suffer from mortality indicates that increased pCO 2 levels may have chronic, but not lethal, effects on this species under these experimental conditions. © The authors 2017.https://www.int-res.com/abstracts/aei/v10/p267-278

Identification of tissue-specific microRNAs from mouse

MicroRNAs (miRNAs) are a new class of noncoding RNAs, which are encoded as short inverted repeats in the genomes of invertebrates and vertebrates [1, 2]. It is believed that miRNAs are modulators of target mRNA translation and stability, although most target mRNAs remain to be identified. Here we describe the identification of 34 novel miRNAs by tissue- specific cloning of approximately 21-nucleotide RNAs from mouse. Almost all identified miRNAs are conserved in the human genome and are also frequently found in nonmammalian vertebrate genomes, such as pufferfish. In heart, liver, or brain, it is found that a single, tissue-specifically expressed miRNA dominates the population of expressed miRNAs and suggests a role for these miRNAs in tissue specification or cell lineage decisions. Finally, a miRNA was identified that appears to be the fruitfly and mammalian ortholog of C. elegans lin-4 stRNA

FGC 1287 and its enigmatic 250 kpc long HI tail in the outskirts of Abell 1367

We present H i and radio continuum, narrow-band H alpha imaging, IFU spectroscopy, and X-ray observations of the FGC 1287 triplet projected similar to 1.8 Mpc west of the galaxy cluster Abell 1367. One triplet member, FGC 1287, displays an exceptionally long, 250 kpc H i tail and an unperturbed stellar disc which are the typical signatures of ram pressure stripping (RPS). To generate detectable RPS signatures the presence of an Intracluster medium ICM or intragroup medium IGM with sufficient density to produce RPS at a realistic velocity relative to the ICM or IGM is a prerequisite. However, XMM-Newton observations were not able to detect X-ray emission from the triplet, implying that if a hot ICM/IGM is present, its density, n(e), is less than 2.6 x 10(-5) cm(-3). Higher resolution VLA H i data presented here show FGC 1287's H i disc is truncated and significantly warped, whereas the H i tail is clumpy. TNG H alpha imaging identified three star-forming clumps projected within 20 kpc of FGC 1287's disc, with VIMOS-IFU data confirming two of these are counterparts to H i clumps in the tail. The triplet's H i kinematics, together with H alpha and radio continuum imaging suggests an interaction may have enhanced star formation in FGC 1287's disc, but cannot readily account for the origin of the long H i tail. We consider several scenarios which might reconcile RPS with the non-detection of ICM or IGM X-ray emission but none of these unambiguously explains the origin of the long H i tail.Peer reviewe

Late-onset X-linked adrenal hypoplasia (DAX-1, NR0B1): two new adult-onset cases from a single center

PURPOSE: DAX-1 (NR0B1) is an orphan nuclear receptor, which plays a critical role in development and regulation of the adrenal gland and hypothalamo-pituitary-gonadal axis. Mutations in NR0B1 lead to adrenal hypoplasia congenita (AHC), hypogonadotropic hypogonadism (HH) and azoospermia in men. Presentation is typically with adrenal insufficiency (AI) during infancy or childhood. To date only eight cases/kindreds are reported to have presented in adulthood. METHODS: We describe two new cases of men with DAX-1 mutations who presented in adulthood and who were diagnosed at a large University Hospital. RESULTS: Case 1 presented with AI at 19 years. At 38 years he was diagnosed with HH. Detailed history revealed a brother diagnosed with AI at a similar age. Sequencing of the DAX-1 (NR0B1) gene revealed a heterozygous c.775T > C substitution in exon 1, which changes codon 259 from serine to proline (p.Ser259Pro). Case 2 was diagnosed with AI at 30 years. Aged 37 years he presented with HH and azoospermia. He was treated with gonadotropin therapy but remained azoospermic. Testicular biopsy showed maturational arrest and hypospermatogenesis. Analysis of the NR0B1 gene showed a heterozygous c.836C > T substitution in exon 1, resulting in a change of codon 279 from proline to leucine (p.Pro279Leu). This change alters the structure of the repression helix domain of DAX-1 and affects protein complex interactions with NR5A family members. CONCLUSIONS: We describe two missense mutations within the putative carboxyl-terminal ligand binding domain of DAX-1, presenting with AHC and HH in adulthood, from a single center. DAX-1 mutations may be more frequent in adults than previously recognized. We recommend testing for DAX-1 mutations in all adults with primary AI and HH or impaired fertility where the etiology is unclear