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https://www.readbyqxmd.com/read/28642389/new-haul-of-distant-worlds-casts-doubt-on-planet-nine
#1
Joshua Sokol
No abstract text is available yet for this article.
June 23, 2017: Science
https://www.readbyqxmd.com/read/28640457/primordial-like-enzymes-from-bacteria-with-reduced-genomes
#2
Matteo P Ferla, Jodi L Brewster, Kelsi R Hall, Gary B Evans, Wayne M Patrick
The first cells probably possessed rudimentary metabolic networks, built using a handful of multifunctional enzymes. The promiscuous activities of modern enzymes are often assumed to be relics of this primordial era; however, by definition these activities are no longer physiological. There are many fewer examples of enzymes using a single active site to catalyze multiple physiologically-relevant reactions. Previously, we characterized the promiscuous alanine racemase (ALR) activity of Escherichia coli cystathionine β-lyase (CBL)...
June 22, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28640340/terrestrial-impact-structures-as-geoheritage-an-assessment-method-of-their-scientific-value-and-its-application-to-brazil
#3
Joana P Sánchez, José B R Brilha
Terrestrial impact structures are geological and geomorphological features with particular importance to understand the history and evolution of the planet. Impact structures are scattered around the world but in many countries these features are under threat, essentially due to anthropic factors. Impact structures with higher scientific value should be considered as geological heritage and, consequently, be subjected to geoconservation strategies. In order to select the most important impact structures to be properly conserved and managed, this paper proposes a quantitative assessment method of the scientific value of these structures...
April 2017: Anais da Academia Brasileira de Ciências
https://www.readbyqxmd.com/read/28638074/geochemical-constraints-on-the-hadean-environment-from-mineral-fingerprints-of-prokaryotes
#4
Alexey A Novoselov, Dailto Silva, Jerusa Schneider, Ximena Celeste Abrevaya, Michael S Chaffin, Paloma Serrano, Margareth Sugano Navarro, Maria Josiane Conti, Carlos Roberto de Souza Filho
The environmental conditions on the Earth before 4 billion years ago are highly uncertain, largely because of the lack of a substantial rock record from this period. During this time interval, known as the Hadean, the young planet transformed from an uninhabited world to the one capable of supporting, and inhabited by the first living cells. These cells formed in a fluid environment they could not at first control, with homeostatic mechanisms developing only later. It is therefore possible that present-day organisms retain some record of the primordial fluid in which the first cells formed...
June 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28633089/first-line-panitumumab-plus-folfox4-or-folfiri-in-colorectal-cancer-with-multiple-or-unresectable-liver-metastases-a-randomised-phase-ii-trial-planet-ttd
#5
Alfredo Carrato, Albert Abad, Bartomeu Massuti, Cristina Grávalos, Pilar Escudero, Federico Longo-Muñoz, José-Luis Manzano, Auxiliadora Gómez, María José Safont, Javier Gallego, Beatriz García-Paredes, Carles Pericay, Rosario Dueñas, Fernando Rivera, Ferrán Losa, Manuel Valladares-Ayerbes, Encarnación González, Enrique Aranda
BACKGROUND: In first-line wild-type (WT)-Kirsten rat sarcoma viral oncogene homologue (KRAS) metastatic colorectal cancer (mCRC), panitumumab (Pmab) improves outcomes when added to FOLFOX [folinic acid, 5-fluorouracil, and oxaliplatin] or FOLFIRI [folinic acid, 5-fluorouracil, and irinotecan]. However no trial has directly compared these combinations. METHODS: Multicentre, open-label study in untreated patients ≥ 18 years with (WT)-KRAS mCRC and multiple or unresectable liver-limited disease (LLD) randomised to either Pmab-FOLFOX4 or Pmab-FOLFIRI...
June 17, 2017: European Journal of Cancer
https://www.readbyqxmd.com/read/28625671/intrinsic-parameters-for-the-synthesis-and-tuned-properties-of-amphiphilic-chitosan-drug-delivery-nanocarriers
#6
REVIEW
Marjan Motiei, Soheila Kashanian, Lucian A Lucia, Mozafar Khazaei
Chitosan (CS) is a material derived from chitin, the most abundant biopolymer on the planet. It has shown potential among a wide variety of biomedical applications especially within the context of self-assembling nanocarriers usable in biomedical applications such as drug delivery, macroscopic injectables, tissue-engineering scaffolds, and nano-imaging agents. To date, many reviews have been focused on the biomedical properties and applications of CS-based nanocarriers, but a review is lacking on the role and prospects of different factors such as formulation parameters and preparation conditions on the properties of amphiphilic chitosan nanocarriers (ACNs) that have shown critical value in advancing drug delivery...
June 15, 2017: Journal of Controlled Release: Official Journal of the Controlled Release Society
https://www.readbyqxmd.com/read/28621762/the-landscape-of-the-emergence-of-life
#7
Sohan Jheeta
This paper reports on the various nuances of the origins of life on Earth and highlights the latest findings in that arena as reported at the Network of Researchers on Horizontal Gene Transfer and the Last Universal Common Ancestor (NoR HGT and LUCA) which was held from the 3-4th November 2016 at the Open University, UK. Although the answers to the question of the origin of life on Earth will not be fathomable anytime soon, a wide variety of subject matter was able to be covered, ranging from examining what constitutes a LUCA, looking at viral connections and "from RNA to DNA", i...
June 16, 2017: Life
https://www.readbyqxmd.com/read/28612096/the-birth-of-the-synapse
#8
REVIEW
Saak V Ovsepian
It has long been held that the rise of neurons as a specialized cell type also marked the onset of the grand evolutionary journey for chemical synapses. Research over recent decades has shown, however, that the most dynamic chapters of synaptic history have been 'written' out of the context of neurobiology and neuronal evolution, dating back to the early metazoa and unicellular living forms. Here, I consider and discuss emerging evidence suggesting the exaptive origin of chemical synapses, via tinkering and neo-functionalization of already existent junctional morphologies and constituents of primeval paracrine signalling...
June 13, 2017: Brain Structure & Function
https://www.readbyqxmd.com/read/28611223/enhanced-interplanetary-panspermia-in-the-trappist-1-system
#9
Manasvi Lingam, Abraham Loeb
We present a simple model for estimating the probability of interplanetary panspermia in the recently discovered system of seven planets orbiting the ultracool dwarf star TRAPPIST-1 and find that panspermia is potentially orders of magnitude more likely to occur in the TRAPPIST-1 system compared with the Earth-to-Mars case. As a consequence, we argue that the probability of abiogenesis is enhanced on the TRAPPIST-1 planets compared with the solar system. By adopting models from theoretical ecology, we show that the number of species transferred and the number of life-bearing planets are also likely to be higher because of the increased rates of immigration...
June 13, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28610890/the-algal-revolution
#10
REVIEW
Juliet Brodie, Cheong Xin Chan, Olivier De Clerck, J Mark Cock, Susana M Coelho, Claire Gachon, Arthur R Grossman, Thomas Mock, John A Raven, Alison G Smith, Hwan Su Yoon, Debashish Bhattacharya
Algae are (mostly) photosynthetic eukaryotes that occupy multiple branches of the tree of life, and are vital for planet function and health. In this review, we highlight a transformative period in studies of the evolution and functioning of this extraordinary group of organisms and their potential for novel applications, wrought by high-throughput 'omic' and reverse genetic methods. We cover the origin and diversification of algal groups, explore advances in understanding the link between phenotype and genotype, consider algal sex determination, and review progress in understanding the roots of algal multicellularity...
June 10, 2017: Trends in Plant Science
https://www.readbyqxmd.com/read/28610553/zombie-projects-negative-networks-and-multigenerational-science-the-temporality-of-the-international-map-of-the-world
#11
William Rankin
The International Map of the World was a hugely ambitious scheme to create standardized maps of the entire world. It was first proposed in 1891 and remained a going concern until 1986. Over the course of the project's official life, nearly every country in the world took part, and map sheets were published showing all but a few areas of the planet. But the project ended quite unceremoniously, repudiated by cartographers and mapping institutions alike, and it is now remembered as a 'sad story' of network failure...
June 2017: Social Studies of Science
https://www.readbyqxmd.com/read/28609856/a-new-species-of-dusky-salamander-amphibia-plethodontidae-desmognathus-from-the-eastern-gulf-coastal-plain-of-the-united-states-and-a-redescription-of%C3%A2-d-auriculatus
#12
D Bruce Means, Jennifer Y Lamb, Joseph Bernardo
The Coastal Plain of the southeastern U. S. is one of the planet's top biodiversity hotspots and yet many taxa have not been adequately studied. The plethodontid salamander, Desmognathus auriculatus, was originally thought to occur from east Texas to Virginia, a range spanning dozens of interfluves and large river systems. Beamer and Lamb (2008) found five independent mitochondrial lineages of what has been called D. auriculatus in the Atlantic Coastal Plain, but did not examine the extensive distribution of D...
May 10, 2017: Zootaxa
https://www.readbyqxmd.com/read/28608975/uniform-supersonic-chemical-reactors-30%C3%A2-years-of-astrochemical-history-and-future-challenges
#13
REVIEW
Alexey Potapov, André Canosa, Elena Jiménez, Bertrand Rowe
The interstellar medium is of great interest to us as the place where stars and planets are born and from where, probably, the molecular precursors of life came to Earth. Astronomical observations, astrochemical modeling, and laboratory astrochemistry should go hand in hand to understand the chemical pathways to the formation of stars, planets, and biological molecules. We review here laboratory experiments devoted to investigations on the reaction dynamics of species of astrochemical interest at the temperatures of the interstellar medium and which were performed by using one of the most popular techniques in the field, CRESU...
February 3, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28607079/age-of-jupiter-inferred-from-the-distinct-genetics-and-formation-times-of-meteorites
#14
Thomas S Kruijer, Christoph Burkhardt, Gerrit Budde, Thorsten Kleine
The age of Jupiter, the largest planet in our Solar System, is still unknown. Gas-giant planet formation likely involved the growth of large solid cores, followed by the accumulation of gas onto these cores. Thus, the gas-giant cores must have formed before dissipation of the solar nebula, which likely occurred within less than 10 My after Solar System formation. Although such rapid accretion of the gas-giant cores has successfully been modeled, until now it has not been possible to date their formation. Here, using molybdenum and tungsten isotope measurements on iron meteorites, we demonstrate that meteorites derive from two genetically distinct nebular reservoirs that coexisted and remained spatially separated between ∼1 My and ∼3-4 My after Solar System formation...
June 12, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28604740/immiscible-hydrocarbon-fluids-in-the-deep-carbon-cycle
#15
Fang Huang, Isabelle Daniel, Hervé Cardon, Gilles Montagnac, Dimitri A Sverjensky
The cycling of carbon between Earth's surface and interior governs the long-term habitability of the planet. But how carbon migrates in the deep Earth is not well understood. In particular, the potential role of hydrocarbon fluids in the deep carbon cycle has long been controversial. Here we show that immiscible isobutane forms in situ from partial transformation of aqueous sodium acetate at 300 °C and 2.4-3.5 GPa and that over a broader range of pressures and temperatures theoretical predictions indicate that high pressure strongly opposes decomposition of isobutane, which may possibly coexist in equilibrium with silicate mineral assemblages...
June 12, 2017: Nature Communications
https://www.readbyqxmd.com/read/28600638/angling-into-the-future-ten-commandments-for-recreational-fisheries-science-management-and-stewardship-in-a-good-anthropocene
#16
Laura K Elmer, Lisa A Kelly, Stephanie Rivest, S Clay Steell, William M Twardek, Andy J Danylchuk, Robert Arlinghaus, Joseph R Bennett, Steven J Cooke
A new geological epoch, the "Anthropocene", has been defined as the period in which humans have had substantial geological and ecological influence on the planet. A positive future for this epoch can be referred to as the "good Anthropocene" and would involve effective management strategies and changes in human behavior that promote the sustainability and restoration of ecosystems. Recreational fisheries hold significant social, cultural, and economic value and can generate many benefits when managed sustainably and thus be an integral part of a "good Anthropocene"...
June 9, 2017: Environmental Management
https://www.readbyqxmd.com/read/28596364/xenon-isotopes-in-67p-churyumov-gerasimenko-show-that-comets-contributed-to-earth-s-atmosphere
#17
B Marty, K Altwegg, H Balsiger, A Bar-Nun, D V Bekaert, J-J Berthelier, A Bieler, C Briois, U Calmonte, M Combi, J De Keyser, B Fiethe, S A Fuselier, S Gasc, T I Gombosi, K C Hansen, M Hässig, A Jäckel, E Kopp, A Korth, L Le Roy, U Mall, O Mousis, T Owen, H Rème, M Rubin, T Sémon, C-Y Tzou, J H Waite, P Wurz
The origin of cometary matter and the potential contribution of comets to inner-planet atmospheres are long-standing problems. During a series of dedicated low-altitude orbits, the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) on the Rosetta spacecraft analyzed the isotopes of xenon in the coma of comet 67P/Churyumov-Gerasimenko. The xenon isotopic composition shows deficits in heavy xenon isotopes and matches that of a primordial atmospheric component. The present-day Earth atmosphere contains 22 ± 5% cometary xenon, in addition to chondritic (or solar) xenon...
June 9, 2017: Science
https://www.readbyqxmd.com/read/28594021/phase-diagram-of-water-methane-by-first-principles-thermodynamics-discovery-of-mh-iv-and-mh-v-hydrates
#18
Xiaoxiao Cao, Yingying Huang, Xue Jiang, Yan Su, Jijun Zhao
Searching novel gas hydrates is an enduring topic of scientific investigations, owing to its outstanding implications on planetology, the origin of life and the exploitation of energy resources. Taking the methane-water system as a representative, we disclose two new dense methane hydrate phases (MH-IV and MH-V) using the Monte-Carlo packing algorithm and density-functional theory (DFT) optimization. Both of these methane clathrates with (CH4)(H2O)4 stoichiometry can be regarded as filled ices, since their hydrogen bond networks are closely related to that of ice i and ice XI, respectively...
June 21, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28593905/targeting-and-inactivation-of-bacterial-toxins-by-human-defensins
#19
REVIEW
Elena Kudryashova, Stephanie M Seveau, Dmitri S Kudryashov
Defensins, as a prominent family of antimicrobial peptides (AMP), are major effectors of the innate immunity with a broad range of immune modulatory and antimicrobial activities. In particular, defensins are the only recognized fast-response molecules that can neutralize a broad range of bacterial toxins, many of which are among the deadliest compounds on the planet. For a decade, the mystery of how a small and structurally conserved group of peptides can neutralize a heterogeneous group of toxins with little to no sequential and structural similarity remained unresolved...
June 14, 2017: Biological Chemistry
https://www.readbyqxmd.com/read/28593879/deciphering-the-route-to-cyclic-monoterpenes-in-chrysomelina-leaf-beetles-source-of-new-biocatalysts-for-industrial-application
#20
Antje Burse, Wilhelm Boland
The drastic growth of the population on our planet requires the efficient and sustainable use of our natural resources. Enzymes are indispensable tools for a wide range of industries producing food, pharmaceuticals, pesticides, or biofuels. Because insects constitute one of the most species-rich classes of organisms colonizing almost every ecological niche on earth, they have developed extraordinary metabolic abilities to survive in various and sometimes extreme habitats. Despite this metabolic diversity, insect enzymes have only recently generated interest in industrial applications because only a few metabolic pathways have been sufficiently characterized...
May 8, 2017: Zeitschrift Für Naturforschung. C, A Journal of Biosciences
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