bluuebunny/crossref_metadata_2025_split huggingface dataset:
Deep mitochondrial introgression and hybridization among ecologically divergent vole species
Authors: Bastos‐Silveira Cristiane , Santos Sara M. , Monarca Rita , Mathias Maria da Luz , Heckel Gerald 
Published: September 2012

AbstractThe completion of speciation is typically difficult to ascertain in rapidly diverging taxa but the amount of hybridization and gene flow in sympatry or parapatry contains important information about the level of reproductive isolation achieved. Here, we examined the progress in speciation between the Mediterranean (Microtus duodecimcostatus) and the Lusitanian pine vole (M. lusitanicus), which are part of the most rapid radiation of species known in mammals. These two Iberian pine voles are classified as separate species because of differences in morphology and ecology, but relatively many ambiguous individuals can be found in sympatric conditions. Our phylogenetic analyses of rangewide data from the mitochondrial cytochrome b gene (mtDNA) demonstrated high levels of diversity and a basal separation in two parapatric lineages. However, mtDNA affiliation was at odds with morphological classification or geographical distribution of the taxa. In contrast, statistical analyses of microsatellites (nucDNA) showed two clear genetic clusters in allopatry and sympatry generally matching morphological classification. This cytonuclear discordance over a large geographic area suggests historical introgression of mtDNA from M. duodecimcostatus to M. lusitanicus. There was statistical evidence for at least two recent hybrids in the sympatry zone but gene flow is apparently low given clear‐cut differences in nucDNA. Our results indicate a relatively advanced speciation process in these Iberian pine voles without fully established reproductive isolation. This situation enables use of combined population genomic and experimental approaches for the separation of patterns and mechanisms in the ongoing explosive diversification of these and other Arvicoline rodents in the future.
Environmental conditions affect spatial genetic structures and dispersal patterns in a solitary rodent
Authors: Messier Gabrielle Dubuc , Garant Dany , Bergeron Patrick , Réale Denis 
Published: September 2012

AbstractThe study of the spatial distribution of relatives in a population under contrasted environmental conditions provides critical insights into the flexibility of dispersal behaviour and the role of environmental conditions in shaping population relatedness and social structure. Yet few studies have evaluated the effects of fluctuating environmental conditions on relatedness structure of solitary species in the wild. The aim of this study was to determine the impact of interannual variations in environmental conditions on the spatial distribution of relatives [spatial genetic structure (SGS)] and dispersal patterns of a wild population of eastern chipmunks (Tamias striatus), a solitary rodent ofNorthAmerica. Eastern chipmunks depend on the seed of masting trees for reproduction and survival. Here, we combined the analysis of theSGSof adults with direct estimates of juvenile dispersal distance during six contrasted years with different dispersal seasons, population sizes and seed production. We found that environmental conditions influences the dispersal distances of juveniles and that male juveniles dispersed farther than females. The extent of theSGSof adult females varied between years and matched the variation in environmental conditions. In contrast, theSGSof males did not vary between years. We also found a difference inSGSbetween males and females that was consistent with male‐biased dispersal. This study suggests that both the dispersal behaviour and the relatedness structure in a population of a solitary species can be relatively labile and change according to environmental conditions.
Geographical and ecological stability of the symbiotic mid‐gut microbiota in European firebugs, Pyrrhocoris apterus (Hemiptera, Pyrrhocoridae)
Authors: Sudakaran Sailendharan , Salem Hassan , Kost Christian , Kaltenpoth Martin 
Published: September 2012

AbstractSymbiotic bacteria often play an essential nutritional role for insects, thereby allowing them to exploit novel food sources and expand into otherwise inaccessible ecological niches. Although many insects are inhabited by complex microbial communities, most studies on insect mutualists so far have focused on single endosymbionts and their interactions with the host. Here, we provide a comprehensive characterization of the gut microbiota of the red firebug (Pyrrhocoris apterus, Hemiptera, Pyrrhocoridae), a model organism for physiological and endocrinological research. A combination of several culture‐independent techniques (454 pyrosequencing, quantitative PCR and cloning/sequencing) revealed a diverse community of likely transient bacterial taxa in the mid‐gut regions M1, M2 and M4. However, the completely anoxic M3 region harboured a distinct microbiota consisting of facultative and obligate anaerobes including Actinobacteria (Coriobacterium glomerans and Gordonibacter sp.), Firmicutes (Clostri‐dium sp. and Lactococcus lactis) and Proteobacteria (Klebsiella sp. and a previously undescribed Rickettsiales bacterium). Characterization of the M3 microbiota in different life stages of P. apterus indicated that the symbiotic bacterial community is vertically transmitted and becomes well defined between the second and third nymphal instar, which coincides with the initiation of feeding. Comparing the mid‐gut M3 microbial communities of P. apterus individuals from five different populations and after feeding on three different diets revealed that the community composition is qualitatively and quantitatively very stable, with the six predominant taxa being consistently abundant. Our findings suggest that the firebug mid‐gut microbiota constitutes a functionally important and possibly coevolved symbiotic community.
Low population genetic differentiation in the Orchidaceae: implications for the diversification of the family
Authors: Phillips Ryan D. , Dixon Kingsley W. , Peakall Rod 
Published: September 2012

AbstractA leading hypothesis for the immense diversity of the Orchidaceae is that skewed mating success and small, disjunct populations lead to strong genetic drift and switches between adaptive peaks. This mechanism is only possible under conditions of low gene flow that lead to high genetic differentiation among populations. We tested whether orchids typically exhibit high levels of population genetic differentiation by conducting a meta‐analysis to compare mean levels of population genetic differentiation (FST) between orchids and other diverse families and between rare and common orchids. Compared with other families, the Orchidaceae is typically characterized by relatively low genetic differentiation among populations (mean FST = 0.146) at allozyme loci. Rare terrestrial orchids showed higher population genetic differentiation than common orchids, although this value was still lower than the mean for most plant families. All lines of evidence suggest that orchids are typically characterized by low levels of population genetic differentiation, even in species with naturally disjunct populations. As such, we found no strong evidence that genetic drift in isolated populations has played a major role in the diversification of the Orchidaceae. Further research into the diversification of the family needs to unravel the relative roles of biotic and environmental selective pressures in the speciation of orchids.
Genome scans reveal candidate regions involved in the adaptation to host plant in the pea aphid complex
Authors: Jaquiéry J. , Stoeckel S. , Nouhaud P. , Mieuzet L. , Mahéo F. , Legeai F. , Bernard N. , Bonvoisin A. , Vitalis R. , Simon J‐C. 
Published: September 2012

AbstractA major goal in evolutionary biology is to uncover the genetic basis of adaptation. Divergent selection exerted on ecological traits may result in adaptive population differentiation and reproductive isolation and affect differentially the level of genetic divergence along the genome. Genome‐wide scan of large sets of individuals from multiple populations is a powerful approach to identify loci or genomic regions under ecologically divergent selection. Here, we focused on the pea aphid, a species complex of divergent host races, to explore the organization of the genomic divergence associated with host plant adaptation and ecological speciation. We analysed 390 microsatellite markers located at variable distances from predicted genes in replicate samples of sympatric populations of the pea aphid collected on alfalfa, red clover and pea, which correspond to three common host‐adapted races reported in this species complex. Using a method that accounts for the hierarchical structure of our data set, we found a set of 11 outlier loci that show higher genetic differentiation between host races than expected under the null hypothesis of neutral evolution. Two of the outliers are close to olfactory receptor genes and three other nearby genes encoding salivary proteins. The remaining outliers are located in regions with genes of unknown functions, or which functions are unlikely to be involved in interactions with the host plant. This study reveals genetic signatures of divergent selection across the genome and provides an inventory of candidate genes responsible for plant specialization in the pea aphid, thereby setting the stage for future functional studies.
PDZ domains of RseP are not essential for sequential cleavage of RseA or stress‐induced σE activation in vivo
Authors: Hizukuri Yohei , Akiyama Yoshinori 
Published: September 2012

SummaryThe Escherichia coli σE extracytoplasmic stress response monitors and responds to folding stress in the cell envelope. A protease cascade directed at RseA, a membrane‐spanning anti‐σ that inhibits σE activity, controls this critical signal‐transduction system. Stress cues activate DegS to cleave RseA; a second cleavage by RseP releases RseA from the membrane, enabling its rapid degradation. Stress control of proteolysis requires that RseP cleavage is dependent on DegS cleavage. Recent in vitro and structural studies found that RseP cleavage requires binding of RseP PDZ‐C to the newly exposed C‐terminal residue (Val148) of RseA, generated by DegS cleavage, explaining dependence. We tested this mechanism in vivo. Neither mutation in the putative PDZ ligand‐binding regions nor even deletion of entire RseP PDZ domains had significant effects on RseA cleavage in vivo, and the C‐terminal residue of DegS‐processed RseA also little affected RseA cleavage. Indeed, strains with a chromosomal rseP gene deleted for either PDZ domain and strains with a chromosomal rseA V148 mutation grew normally and exhibited almost normal σE activation in response to stress signals. We conclude that recognition of the cleaved amino acid by the RseP PDZ domain is not essential for sequential cleavage of RseA and σE stress response in vivo.
Vortex–Vortex Interactions for the Maintenance of Blocking. Part I: The Selective Absorption Mechanism and a Case Study
Authors: Yamazaki Akira , Itoh Hisanori 
Published: September 2012

Abstract
A new block maintenance mechanism, the selective absorption mechanism (SAM), is proposed. According to this mechanism, which is based on vortex–vortex interactions (i.e., the interactions between a blocking anticyclone and synoptic eddies with the same polarity), a blocking anticyclone actively and selectively absorbs synoptic anticyclones (strictly, air parcels with low potential vorticity). The blocking anticyclone, which is thus supplied with low potential vorticity of the synoptic anticyclones, can subsist for a prolonged period, withstanding dissipation.
The SAM was verified in a case study through trajectory analysis. Ten actual cases of blocking were examined. Trajectories were calculated by tracing parcels originating from synoptic anticyclones and cyclones located upstream of the blocking. Parcels starting from anticyclones were attracted to and absorbed by the blocking anticyclone, whereas parcels from cyclones were repelled by the blocking anticyclone and attracted to the blocking cyclone, if one was present.
The results show that the SAM is effective in the maintenance of observed cases of blocking. In addition, the uniqueness and distinction of the SAM from other previously proposed maintenance mechanisms are discussed.
Vortex–Vortex Interactions for the Maintenance of Blocking. Part II: Numerical Experiments
Authors: Yamazaki Akira , Itoh Hisanori 
Published: September 2012

Abstract
The selective absorption mechanism (SAM), newly proposed in Part I of this study on the maintenance mechanism of blocking, is verified through numerical experiments. The experiments were based on the nonlinear equivalent-barotropic potential vorticity equation, with varying conditions with respect to the shape and amplitude of blocking, and characteristics of storm tracks (displacement and strength) and background zonal flow.
The experiments indicate that the SAM effectively maintains blocking, irrespective of the above conditions. At first, by applying a channel model on a β plane, numerical experiments were conducted using a uniform background westerly with and without a jet. The results show that the presence of a jet promotes the effectiveness of the SAM. Then, two types of spherical model experiments were also performed. In idealized experiments, the SAM was as effective as the β-plane model in explaining the maintenance of blocking. Moreover, experiments performed under realistic meteorological conditions showed that the SAM maintained a real block, demonstrating that the SAM is effective.
These results, and the case study in Part I, verify that the SAM is the effective general maintenance mechanism for blocking.
Improvements to an Empirical Parameterization of Heterogeneous Ice Nucleation and Its Comparison with Observations
Authors: Phillips Vaughan T. J. , Demott Paul J. , Andronache Constantin , Pratt Kerri A. , Prather Kimberly A. , Subramanian R. , Twohy Cynthia 
Published: September 2012

AbstractA framework for an empirical parameterization (EP) of heterogeneous nucleation of ice crystals by multiple species of aerosol material in clouds was proposed in a 2008 paper by the authors. The present paper reports improvements to specification of a few of its empirical parameters. These include temperatures for onset of freezing, baseline surface areas of aerosol observed in field campaigns over Colorado, and new parameters for properties of black carbon, such as surface hydrophilicity and organic coatings. The EP’s third group of ice nucleus (IN) aerosols is redefined as that of primary biological aerosol particles (PBAPs), replacing insoluble organic aerosols. A fourth group of IN is introduced—namely, soluble organic aerosols.The new EP predicts IN concentrations that agree well with aircraft data from selected traverses of shallow wave clouds observed in five flights (1, 3, 4, 6, and 12) of the 2007 Ice in Clouds Experiment–Layer Clouds (ICE-L). Selected traverses were confined to temperatures between about −25° and −29°C in layer cloud without homogeneously nucleated ice from aloft. Some of the wave clouds were affected by carbonaceous aerosols from biomass burning and by dust from dry lakebeds and elsewhere. The EP predicts a trend between number concentrations of heterogeneously nucleated ice crystals and apparent black carbon among the five wave clouds, observed by aircraft in ICE-L. It is predicted in terms of IN activity of black carbon.The EP’s predictions are consistent with laboratory and field observations not used in its construction, for black carbon, dust, primary biological aerosols, and soluble organics. The EP’s prediction of biological ice nucleation is validated using coincident field observations of PBAP IN and PBAPs in Colorado.
A Diagnostic Indicator of the Stability of the Atlantic Meridional Overturning Circulation in CCSM3
Authors: Liu Wei , Liu Zhengyu 
Published: September 2012

AbstractA diagnostic indicator ΔMov is proposed in this paper to monitor the stability of the Atlantic meridional overturning circulation (AMOC). The ΔMov is a diagnostic for a basinwide salt-advection feedback and defined as the difference between the freshwater transport induced by the AMOC across the southern border of the Atlantic Ocean and the overturning liquid freshwater transport from the Arctic Ocean to the North Atlantic. As validated in the Community Climate System Model, version 3 (CCSM3), for an AMOC in the conveyor state, a positive ΔMov (freshwater convergence) in the Atlantic basin indicates a monostable AMOC and a negative ΔMov (freshwater divergence) indicates a bistable AMOC. Based on ΔMov, the authors investigate the AMOC stability in the Last Glacial Maximum (LGM) and analyze the modulation of the AMOC stability by an open/closed Bering Strait. Moreover, the authors estimate that the real AMOC is likely to be bistable in the present day, since some observations suggest a negative ΔMov (freshwater divergence) is currently in the Atlantic basin. However, this estimation is very sensitive to the choice of the observational data.
Impact of Daily Arctic Sea Ice Variability in CAM3.0 during Fall and Winter
Authors: Dammann Dyre O. , Bhatt Uma S. , Langen Peter L. , Krieger Jeremy R. , Zhang Xiangdong 
Published: September 2012

AbstractClimate projections suggest that an ice-free summer Arctic Ocean is possible within several decades and with this comes the prospect of increased ship traffic and safety concerns. The daily sea ice concentration tendency in five Coupled Model Intercomparison Project phase 5 (CMIP5) simulations is compared with observations to reveal that many models underestimate this quantity that describes high-frequency ice movements, particularly in the marginal ice zone. To investigate whether high-frequency ice variability impacts the atmosphere, the Community Atmosphere Model, version 3.0 (CAM3.0), is forced by sea ice with and without daily fluctuations. Two 100-member ensemble experiments with daily varying (DAILY) and smoothly varying (SMTH) sea ice are conducted, along with a climatological control, for an anomalously low ice period (August 2006–November 2007). Results are presented for three periods: September 2006, October 2006, and December–February (DJF) 2006/07. The atmospheric response differs between DAILY and SMTH. In September, sea ice differences lead to an anomalous high and weaker storm activity over northern Europe. During October, the ice expands equatorward faster in DAILY than SMTH in the Siberian seas and leads to a local response of near-surface cooling. In DJF, there is a 1.5-hPa positive sea level pressure anomaly over North America, leading to anomalous northerly flow and anomalously cool continental U.S. temperatures. While the atmospheric responses are modest, the differences arising from high temporal frequency ice variability cannot be ignored. Increasing the accuracy of coupled model sea ice variations on short time scales is needed to improve short-term coupled model forecasts.
Dynamic ultrasound imaging—A multivariate approach for the analysis and comparison of time-dependent musculoskeletal movements
Authors: Löfstedt Tommy , Ahnlund Olof , Peolsson Michael , Trygg Johan 
Published: September 2012

AbstractBackgroundMuscle functions are generally assumed to affect a wide variety of conditions and activities, including pain, ischemic and neurological disorders, exercise and injury. It is therefore very desirable to obtain more information on musculoskeletal contributions to and activity during clinical processes such as the treatment of muscle injuries, post-surgery evaluations, and the monitoring of progressive degeneration in neuromuscular disorders.The spatial image resolution achievable with ultrasound systems has improved tremendously in the last few years and it is nowadays possible to study skeletal muscles in real-time during activity. However, ultrasound imaging has an inherent problem that makes it difficult to compare different measurement series or image sequences from two or more subjects. Due to physiological differences between different subjects, the ultrasound sequences will be visually different – partly because of variation in probe placement and partly because of the difficulty of perfectly reproducing any given movement.MethodsUltrasound images of the biceps and calf of a single subject were transformed to achieve congruence and then efficiently compressed and stacked to facilitate analysis using a multivariate method known as O2PLS. O2PLS identifies related and unrelated variation in and between two sets of data such that different phases of the studied movements can be analysed. The methodology was used to study the dynamics of the Achilles tendon and the calf and also the Biceps brachii and upper arm. The movements of these parts of the body are both of interest in clinical orthopaedic research.ResultsThis study extends the novel method of multivariate analysis of congruent images (MACI) to facilitate comparisons between two series of ultrasound images. This increases its potential range of medical applications and its utility for detecting, visualising and quantifying the dynamics and functions of skeletal muscle.ConclusionsThe most important results of this study are that MACI with O2PLS is able to consistently extract meaningful variability from pairs of ultrasound sequences. The MACI method with O2PLS is a powerful tool with great potential for visualising and comparing dynamics between movements. It has many potential clinical applications in the study of muscle injuries, post-surgery evaluations and evaluations of rehabilitation, and the assessment of athletic training interventions.
Changes in intraocular pressure after pharmacologic pupil dilation
Authors: Kim Joon Mo , Park Ki Ho , Han So Young , Kim Kwan Soo , Kim Dong Myung , Kim Tae Woo , Caprioli Joseph 
Published: September 2012

Abstract

Background
Intraocular pressure (IOP) may vary according to the change of ocular conditions. In this study, we want to assess the effect and mechanism of pupil dilation on IOP in normal subjects.

Methods
We prospectively evaluated 32 eyes of 32 patients (age; 61.7 ± 8.2 years) with normal open angles under diurnal IOP. IOP was measured every two hours from 9 AM to 11 PM for one day to establish baseline values and was measured again for one day to assess the differences after dilation. To induce dilation, we administered 2.5% phenylephrine and 1% tropicamide every 5 minutes from 8:30 AM to 8:45 AM and for every two hours from 11 AM to 9 PM to keep the pupil dilated. Diurnal IOP, biometry, Visante OCT, and laser flare photometry were measured before and after dilation.

Results
We observed a significant increase in IOP after dilation, 1.85 ± 2.01 mmHg (p = 0.002). IOP elevation remained significant until about four hours after dilation. Thereafter, IOP decreased slowly and eventually reached pre-dilation level (p > 0.05). Flare values decreased, and the anterior chamber angle became wider after mydriasis.

Conclusions
Dilation of the pupil significantly and incidentally elevated IOP in normal subjects. Further related studies are warranted to characterize the mechanism of the increased IOP after dilation.