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Landscape structure

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https://www.readbyqxmd.com/read/28214357/nesting-habits-influence-population-genetic-structure-of-a-bee-living-in-anthropogenic-disturbance
#1
J L Vickruck, M H Richards
While most organisms are negatively affected by anthropogenic disturbance, a few species thrive in landscapes altered by humans. Typically, native bees are negatively impacted by anthropogenic environmental change, including habitat alteration and climate change. Here we investigate the population structure of the eastern carpenter bee Xylocopa virginica, a generalist pollinator with a broad geographic range spanning eastern North America. Eastern carpenter bees now nest almost exclusively in human made wooden structures, linking their geographic distribution and population structure to human activities and disturbance...
February 18, 2017: Molecular Ecology
https://www.readbyqxmd.com/read/28212459/structural-studies-of-nicotinoids-cotinine-vs-nicotine
#2
Iciar Uriarte, Cristóbal Pérez, Elena Caballero-Mancebo, Francisco J Basterretxea, Alberto Lesarri, José A Fernández, Emilio J Cocinero
Nicotinoids are agonists of the acetylcholine receptor (nAChR) and play important biochemical and pharmacological roles. Here we report on the structural and conformational landscape of cotinine, and compare its molecular properties with the nicotine prototype, from which it only differs in the addition of a carbonyl group. The investigation of cotinine included a theoretical survey of the effects of rotamerization of the pyridine moiety, the puckering of the pyrrolidinone ring and the internal rotation of the methyl group...
February 17, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28211491/interference-between-variants-of-peach-latent-mosaic-viroid-reveals-novel-features-of-its-fitness-landscape-implications-for-detection
#3
Pedro Serra, Edson Bertolini, M Carmen Martínez, Mariano Cambra, Ricardo Flores
Natural populations of peach latent mosaic viroid (PLMVd) are complex mixtures of variants. During routine testing, TaqMan rtRT-PCR and RNA gel-blot hybridization produced discordant results with some PLMVd isolates. Analysis of the corresponding populations showed that they were exclusively composed of variants (of class II) with a structural domain different from that of the reference and many other variants (of class I) targeted by the TaqMan rtRT-PCR probe. Bioassays in peach revealed that a representative PLMVd variant of class II replicated without symptoms, generated a progeny with low nucleotide diversity, and, intriguingly, outcompeted a representative symptomatic variant of class I when co-inoculated in equimolecular amounts...
February 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28209969/solution-of-the-spatial-neutral-model-yields-new-bounds-on-the-amazonian-species-richness
#4
Yahav Shem-Tov, Matan Danino, Nadav M Shnerb
Neutral models, in which individual agents with equal fitness undergo a birth-death-mutation process, are very popular in population genetics and community ecology. Usually these models are applied to populations and communities with spatial structure, but the analytic results presented so far are limited to well-mixed or mainland-island scenarios. Here we combine analytic results and numerics to obtain an approximate solution for the species abundance distribution and the species richness for the neutral model on continuous landscape...
February 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28209157/stakeholder-perspectives-on-the-implementation-of-genetic-carrier-screening-in-a-changing-landscape
#5
Kim C A Holtkamp, Evelien M Vos, Tessel Rigter, Phillis Lakeman, Lidewij Henneman, Martina C Cornel
BACKGROUND: In most countries, genetic carrier screening is neither offered, nor embedded in mainstream healthcare. Technological developments have triggered a two-fold transition in carrier screening: the expansion from screening one single disorder to many disorders simultaneously, and offering screening universally, regardless of ancestry. This study aims to identify general and population-specific barriers and needs reflected by stakeholders regarding the implementation of carrier screening in a changing landscape...
February 16, 2017: BMC Health Services Research
https://www.readbyqxmd.com/read/28208365/expansion-of-cooperatively-growing-populations-optimal-migration-rates-and-habitat-network-structures
#6
Kai-Cheng Yang, Zhi-Xi Wu, Petter Holme, Etsuko Nonaka
Range expansion of species is driven by the interactions among individual- and population-level processes and the spatial pattern of habitats. In this work we study how cooperatively growing populations spread on networks representing the skeleton of complex landscapes. By separating the slow and fast variables of the expansion process, we are able to give analytical predictions for the critical conditions that divide the dynamic behaviors into different phases (extinction, localized survival, and global expansion)...
January 2017: Physical Review. E
https://www.readbyqxmd.com/read/28207176/detecting-state-changes-for-ecosystem-conservation-with-long-term-monitoring-of-species-composition
#7
T J Mason, D A Keith, A D Letten
Effective conservation requires an understanding not only of contemporary vegetation distributions in the landscape, but also cognizance of vegetation transitions over time with the goal of maintaining persistence of all states within the landscape. Using a state and transition model framework, we investigated temporal transitions over 31 years in species composition among five upland swamp vegetation communities in southeastern Australia. We applied fuzzy clustering to document transitions across communities; evaluated the resilience and resistance of communities to change; and explored the relationship between ecosystem states and major environmental factors posited to structure the system...
October 4, 2016: Ecological Applications: a Publication of the Ecological Society of America
https://www.readbyqxmd.com/read/28205107/tree-biomass-in-the-swiss-landscape-nationwide-modelling-for-improved-accounting-for-forest-and-non-forest-trees
#8
B Price, A Gomez, L Mathys, O Gardi, A Schellenberger, C Ginzler, E Thürig
Trees outside forest (TOF) can perform a variety of social, economic and ecological functions including carbon sequestration. However, detailed quantification of tree biomass is usually limited to forest areas. Taking advantage of structural information available from stereo aerial imagery and airborne laser scanning (ALS), this research models tree biomass using national forest inventory data and linear least-square regression and applies the model both inside and outside of forest to create a nationwide model for tree biomass (above ground and below ground)...
March 2017: Environmental Monitoring and Assessment
https://www.readbyqxmd.com/read/28204868/specific-vicariance-of-two-primeval-lowland-forest-lichen-indicators
#9
Dariusz Kubiak, Piotr Osyczka
To date, the lichens Chrysothrix candelaris and Varicellaria hemisphaerica have been classified as accurate primeval lowland forest indicators. Both inhabit particularly valuable remnants of oak-hornbeam forests in Europe, but tend toward a specific kind of vicariance on a local scale. The present study was undertaken to determine habitat factors responsible for this phenomenon and verify the indicative and conservation value of these lichens. The main spatial and climatic parameters that, along with forest structure, potentially affect their distribution patterns and abundance were analysed in four complexes with typical oak-hornbeam stands in NE Poland...
February 15, 2017: Environmental Management
https://www.readbyqxmd.com/read/28202709/understanding-in-line-probing-experiments-by-modeling-cleavage-of-non-reactive-rna-nucleotides
#10
Vojtech Mlynsky, Giovanni Bussi
Ribonucleic acid (RNA) is involved in many regulatory and catalytic processes in the cell. The function of any RNA molecule is intimately related with its structure. In-line probing experiments provide valuable structural datasets for a variety of RNAs and are used to characterize conformational changes in riboswitches. However, the structural determinants that lead to differential reactivities in unpaired nucleotides have not been investigated yet. In this work we used a combination of theoretical approaches, i...
February 15, 2017: RNA
https://www.readbyqxmd.com/read/28201879/full-dimensional-ground-and-excited-state-potential-energy-surfaces-and-state-couplings-for-photodissociation-of-thioanisole
#11
Shaohong L Li, Donald G Truhlar
Analytic potential energy surfaces (PESs) and state couplings of the ground and two lowest singlet excited states of thioanisole (C6H5SCH3) are constructed in a diabatic representation based on electronic structure calculations including dynamic correlation. They cover all 42 internal degrees of freedom and a wide range of geometries including the Franck-Condon region and the reaction valley along the breaking S-CH3 bond with the full ranges of the torsion angles. The parameters in the PESs and couplings are fitted to the results of smooth diabatic electronic structure calculations including dynamic electron correlation by the extended multi-configurational quasi-degenerate perturbation theory method for the adiabatic state energies followed by diabatization by the fourfold way...
February 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28199768/photoresponsive-nanosheets-of-polyoxometalates-formed-by-controlled-self-assembly-pathways
#12
Keita Ishiba, Takao Noguchi, Hiroaki Iguchi, Masa-Aki Morikawa, Kenji Kaneko, Nobuo Kimizuka
Anionic Keggin polyoxometalates (POMs) and ether linkage-enriched ammonium ions spontaneously self-assemble into rectangular ultrathin nanosheets in aqueous media. The structural flexibility of the cation is essential to form oriented nanosheets; as demonstrated by single-crystal X-ray diffraction measurements. The difference in initial conditions exerts significant influence on selecting for self-assembly pathways in the energy landscape. Photoillumination of the POM sheets in pure water causes dissolution of reduced POMs, which allowed site-specific etching of nanosheets using laser scanning microscopy...
February 15, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28198816/low-genetic-diversity-and-strong-population-structure-shaped-by-anthropogenic-habitat-fragmentation-in-a-critically-endangered-primate-trachypithecus-leucocephalus
#13
W Wang, Y Qiao, S Li, W Pan, M Yao
Habitat fragmentation may strongly impact population genetic structure and reduce the genetic diversity and viability of small and isolated populations. The white-headed langur (Trachypithecus leucocephalus) is a critically endangered primate species living in a highly fragmented and human-modified habitat in southern China. We examined the population genetic structure and genetic diversity of the species and investigated the environmental and anthropogenic factors that may have shaped its population structure...
February 15, 2017: Heredity
https://www.readbyqxmd.com/read/28196882/trade-offs-between-enzyme-fitness-and-solubility-illuminated-by-deep-mutational-scanning
#14
Justin R Klesmith, John-Paul Bacik, Emily E Wrenbeck, Ryszard Michalczyk, Timothy A Whitehead
Proteins are marginally stable, and an understanding of the sequence determinants for improved protein solubility is highly desired. For enzymes, it is well known that many mutations that increase protein solubility decrease catalytic activity. These competing effects frustrate efforts to design and engineer stable, active enzymes without laborious high-throughput activity screens. To address the trade-off between enzyme solubility and activity, we performed deep mutational scanning using two different screens/selections that purport to gauge protein solubility for two full-length enzymes...
February 14, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28196466/the-transcriptional-landscape-of-basidiosporogenesis-in-mature-pisolithus-microcarpus-basidiocarp
#15
Maíra de Freitas Pereira, André Narvaes da Rocha Campos, Thalita Cardoso Anastacio, Emmanuelle Morin, Sérgio Hermínio Brommonschenkel, Francis Martin, Annegret Kohler, Maurício Dutra Costa
BACKGROUND: Pisolithus microcarpus (Cooke & Massee) G. Cunn is a gasteromycete that produces closed basidiocarps in symbiosis with eucalypts and acacias. The fungus produces a complex basidiocarp composed of peridioles at different developmental stages and an upper layer of basidiospores free of the hyphae and ready for wind dispersal upon the rupture of the basidiocarp pellis. During basidiosporogenesis, a process that takes place inside the basidiocarp peridioles, a conspicuous reserve of fatty acids is present throughout development...
February 14, 2017: BMC Genomics
https://www.readbyqxmd.com/read/28195076/energy-level-alignment-at-planar-organic-heterojunctions-influence-of-contact-doping-and-molecular-orientation
#16
Andreas Opitz
Planar organic heterojunctions are widely used in photovoltaic cells, light-emitting diodes, and bilayer field-effect transistors. The energy level alignment in the devices plays an important role in obtaining the aspired gap arrangement. Additionally, the π-orbital overlap between the involved molecules defines e.g. the charge-separation efficiency in solar cells due to charge-transfer effects. To account for both aspects, direct/inverse photoemission spectroscopy and near edge x-ray absorption fine structure spectroscopy were used to determine the energy level landscape and the molecular orientation at prototypical planar organic heterojunctions...
February 14, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28193289/microgeographical-structure-in-the-major-neotropical-malaria-vector-anopheles-darlingi-using-microsatellites-and-snp-markers
#17
Melina Campos, Jan E Conn, Diego Peres Alonso, Joseph M Vinetz, Kevin J Emerson, Paulo Eduardo Martins Ribolla
BACKGROUND: In recent decades, throughout the Amazon Basin, landscape modification contributing to profound ecological change has proceeded at an unprecedented rate. Deforestation that accompanies human activities can significantly change aspects of anopheline biology, though this may be site-specific. Such local changes in anopheline biology could have a great impact on malaria transmission. The aim of this study was to investigate population genetics of the main malaria vector in Brazil, Anopheles darlingi, from a microgeographical perspective...
February 13, 2017: Parasites & Vectors
https://www.readbyqxmd.com/read/28193203/first-insight-into-the-somatic-mutation-burden-of-neurofibromatosis-type-2-associated-grade-i-and-grade-ii-meningiomas-a-case-report-comprehensive-genomic-study-of-two-cranial-meningiomas-with-vastly-different-clinical-presentation
#18
Ramita Dewan, Alexander Pemov, Amalia S Dutra, Evgenia D Pak, Nancy A Edwards, Abhik Ray-Chaudhury, Nancy F Hansen, Settara C Chandrasekharappa, James C Mullikin, Ashok R Asthagiri, John D Heiss, Douglas R Stewart, Anand V Germanwala
BACKGROUND: Neurofibromatosis type 2 (NF2) is a rare autosomal dominant nervous system tumor predisposition disorder caused by constitutive inactivation of one of the two copies of NF2. Meningiomas affect about one half of NF2 patients, and are associated with a higher disease burden. Currently, the somatic mutation landscape in NF2-associated meningiomas remains largely unexamined. CASE PRESENTATION: Here, we present an in-depth genomic study of benign and atypical meningiomas, both from a single NF2 patient...
February 13, 2017: BMC Cancer
https://www.readbyqxmd.com/read/28188969/interpreting-beta-diversity-components-over-time-to-conserve-metacommunities-in-highly-dynamic-ecosystems
#19
Albert Ruhí, Thibault Datry, John L Sabo
The concept of 'metacommunity', or a set of local communities linked by dispersal, has gained great popularity among community ecologists over the last decade. However, whereas metacommunity research mostly addresses questions on spatial biodiversity patterns at the regional scale, conservation planning requires quantifying temporal variation in those metacommunities, and the contributions that individual (local) habitats make to regional dynamics. Here we propose that recent advances in diversity partitioning methods may allow for a better understanding of metacommunity dynamics and for the identification of keystone habitats...
February 11, 2017: Conservation Biology: the Journal of the Society for Conservation Biology
https://www.readbyqxmd.com/read/28188416/keystone-species-forest-and-landscape-a-model-to-select-protected-areas
#20
Daniela Barbosa da Silva Lins, Fernando Ravanini Gardon, João Frederico da Costa Azevedo Meyer, Rozely Ferreira Dos Santos
The selection of forest fragments for conservation is usually based on spatial parameters as forest size and canopy integrity. This strategy assumes that chosen fragments present high conservation status, ensuring biodiversity and ecological functions. We argue that a well-preserved forest fragment that remains connected by the landscape structure, does not necessarily hold attributes that ensure the presence of keystone species. We also discuss that the presence of keystone species does not always mean that it has the best conditions for its occurrence and maintenance...
February 10, 2017: Environmental Management
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