bluuebunny/crossref_metadata_2025_split huggingface dataset:
Speciation in the Rana chensinensis species complex and its relationship to the uplift of the Qinghai–Tibetan Plateau
Authors: ZHOU WEI‐WEI , WEN YANG , FU JINZHONG , XU YONG‐BIAO , JIN JIE‐QIONG , DING LI , MIN MI‐SOOK , CHE JING , ZHANG YA‐PING 
Published: January 2012

AbstractSpeciation remains a fundamental issue in biology. Herein, we report an investigation into speciation in the Rana chensinensis species complex using DNA sequence data from one mitochondrial and five nuclear genes. A phylogenetic analysis of the data revealed four major clades in the complex, and each of them was found to likely represent a species, including one cryptic species. Ecological niche models were generated from 19 climatic variables for three of the four major clades, which were represented by widespread sampling, including R. chensinensis, Rana kukunoris and the potential cryptic species. Each clade is associated with a unique ecological unit, and this indicates that ecological divergence probably drove speciation. Ecological divergence is likely related to the late Cenozoic orogenesis of the Qinghai–Tibetan Plateau. In addition, gene flow between species was detected but only in peripheral portions of the ranges of the four major clades, thus likely had little influence on the speciation processes. Discordances between mitochondrial and nuclear genes were also found; the nominal species, R. chensinensis, contains multiple maternal clades, suggesting potential mitochondrial introgression between R. chensinensis and R. kukunoris.
Hidden diversity in diatoms of Kenyan Lake Naivasha: a genetic approach detects temporal variation
Authors: STOOF‐LEICHSENRING KATHLEEN R. , EPP LAURA S. , TRAUTH MARTIN H. , TIEDEMANN RALPH 
Published: January 2012

AbstractThis study provides insights into the morphological and genetic diversity in diatoms occurring in core sediments from tropical lakes in Kenya. We developed a genetic survey technique specific for diatoms utilizing a short region (76–67 bp) of the ribulose‐1,5‐bisphosphate carboxylase/oxygenase large subunit (rbcL) gene as genetic barcode. Our analyses (i) validated the use of rbcL as a barcoding marker for diatoms, applied to sediment samples, (ii) showed a significant correlation between the results obtained by morphological and molecular data and (iii) indicated temporal variation in diatom assemblages on the inter‐ and intra‐specific level. Diatom assemblages from a short core from Lake Naivasha show a drastic shift over the last 200 years, as littoral species (e.g. Navicula) are replaced by more planktonic ones (e.g. Aulacoseira). Within that same period, we detected periodic changes in the respective frequencies of distinct haplotype groups of Navicula, which coincide with wet and dry periods of Lake Naivasha between 1820 and 1938 AD. Our genetic analyses on historical lake sediments revealed inter‐ and intra‐specific variation in diatoms, which is partially hidden behind single morphotypes. The occurrence of particular genetic lineages is probably correlated with environmental factors.
Deciphering cell wall integrity signalling in Aspergillus fumigatus: identification and functional characterization of cell wall stress sensors and relevant Rho GTPases
Authors: Dichtl Karl , Helmschrott Christoph , Dirr Franziska , Wagener Johannes 
Published: January 2012

SummaryThe fungal cell wall, a conserved and highly dynamic structure, is essential for virulence and viability of fungal pathogens and is an important antifungal drug target. The cell wall integrity (CWI) signalling pathway regulates shape and biosynthesis of the cell wall. In this work we identified, localized and functionally characterized four putative CWI stress sensors of Aspergillus fumigatus, an airborne opportunistic human pathogen and the cause of invasive aspergillosis. We show that Wsc1 is specifically required for resistance to echinocandin antifungals. MidA is specifically required for elevated temperature tolerance and resistance to the cell wall perturbing agents congo red and calcofluor white. Wsc1, Wsc3 and MidA additionally have overlapping functions and are redundantly required for radial growth and conidiation. We have also analysed the roles of three Rho GTPases that have been implicated in CWI signalling in other fungi. We show that Rho1 is essential and that conditional downregulation of rho1 or deletion of rho2 or rho4 results in severely impaired CWI. Our data indicate significant functional differences between the CWI stress sensors of yeasts and moulds.
The RGSGR amino acid motif of the intercellular signalling protein, HetN, is required for patterning of heterocysts in Anabaena sp. strain PCC 7120
Authors: Higa Kelly C. , Rajagopalan Ramya , Risser Douglas D. , Rivers Orion S. , Tom Sasa K. , Videau Patrick , Callahan Sean M. 
Published: January 2012

SummaryNitrogen‐fixing heterocysts are arranged in a periodic pattern on filaments of the cyanobacterium Anabaena sp. strain PCC 7120 under conditions of limiting combined nitrogen. Patterning requires two inhibitors of heterocyst differentiation, PatS and HetN, which work at different stages of differentiation by laterally suppressing levels of an activator of differentiation, HetR, in cells adjacent to source cells. Here we show that the RGSGR sequence in the 287‐amino‐acid HetN protein, which is shared by PatS, is critical for patterning. Conservative substitutions in any of the five amino acids lowered the extent to which HetN inhibited differentiation when overproduced and altered the pattern of heterocysts in filaments with an otherwise wild‐type genetic background. Conversely, substitution of amino acids comprising the putative catalytic triad of this predicted reductase had no effect on inhibition or patterning. Deletion of putative domains of HetN suggested that the RGSGR motif is the primary component of HetN required for both its inhibitory and patterning activity, and that localization to the cell envelope is not required for patterning of heterocysts. The intercellular signalling proteins PatS and HetN use the same amino acid motif to regulate different stages of heterocyst patterning.
Sacral nerve stimulation enhances epithelial barrier of the rectum: results from a porcine model
Authors: Meurette G. , Blanchard C. , Duchalais‐Dassonneville E. , Coquenlorge S. , Aubert P. , Wong M. , Lehur P.‐A. , Neunlist M. 
Published: January 2012

AbstractBackground  The mechanism of action of sacral nerve stimulation (SNS) remains largely elusive. The aims of this study were to develop a clinically relevant animal model for percutaneous SNS and to describe its effect on the epithelial barrier of the rectum.Methods  Under general anesthesia and after percutaneous electrode placement for S3 nerve root stimulation, six pigs underwent unilateral stimulation and six bilateral stimulation. Animals were stimulated for 3 h using an external pulse generator (1–2.5 V; 14 Hz; 210 μs). Six animals underwent electrode implantation without stimulation and served as controls. Full‐thickness rectal biopsies were performed prior to and after stimulation. Paracellular permeability was evaluated by measuring sulfonic acid flux across the rectal mucosa in Ussing chambers. Histological assessment of mucosal thickness, epithelial desquamation, and mucus expression were performed.Key Results  Percutaneous stimulation resulted in successful anal contractions whose amplitude and uniformity was enhanced following bilateral compared with unilateral stimulation. In controls, paracellular permeability significantly increased during the stimulation period whereas it remained unchanged following unilateral stimulation. In contrast, permeability was significantly reduced by bilateral stimulation. This effect was associated with a concomitant reduction in mucosal thickness and a trend toward increased amount of mucus on surface epithelium compared with controls.Conclusions & Inferences  The development of a porcine model of percutaneous SNS revealed the ability of neuromodulation to reinforce rectal epithelial barrier. Furthermore, our results suggest that SNS could be used for treatment of gastrointestinal pathologies with reduced rectal mucosal barrier functions
Cross‐kingdom interactions matter: fungal‐mediated interactions structure an insect community on oak
Authors: Tack Ayco J. M. , Gripenberg Sofia , Roslin Tomas 
Published: January 2012

Ecology Letters (2012)AbstractAlthough phytophagous insects and plant pathogens frequently share the same host plant, interactions among such phylogenetically distant taxa have received limited attention. Here, we place pathogens and insects in the context of a multitrophic‐level community. Focusing on the invasive powdery mildew Erysiphe alphitoides and the insect community on oak (Quercus robur), we demonstrate that mildew–insect interactions may be mediated by both the host plant and by natural enemies, and that the trait‐specific outcome of individual interactions can range from negative to positive. Moreover, mildew affects resource selection by insects, thereby modifying the distribution of a specialist herbivore at two spatial scales (within and among trees). Finally, a long‐term survey suggests that species‐specific responses to mildew scale up to generate landscape‐level variation in the insect community structure. Overall, our results show that frequently overlooked cross‐kingdom interactions may play a major role in structuring terrestrial plant‐based communities.
Living fast and dying of infection: host life history drives interspecific variation in infection and disease risk
Authors: Johnson Pieter T. J. , Rohr Jason R. , Hoverman Jason T. , Kellermanns Esra , Bowerman Jay , Lunde Kevin B. 
Published: January 2012

Ecology Letters (2012)AbstractParasite infections often lead to dramatically different outcomes among host species. Although an emerging body of ecoimmunological research proposes that hosts experience a fundamental trade‐off between pathogen defences and life‐history activities, this line of inquiry has rarely been extended to the most essential outcomes of host‐pathogen interactions: namely, infection and disease pathology. Using a comparative experimental approach involving 13 amphibian host species and a virulent parasite, we test the hypothesis that ‘pace‐of‐life’ predicts parasite infection and host pathology. Trematode exposure increased mortality and malformations in nine host species. After accounting for evolutionary history, species that developed quickly and metamorphosed smaller (‘fast‐species’) were particularly prone to infection and pathology. This pattern likely resulted from both weaker host defences and greater adaptation by parasites to infect common hosts. Broader integration between life history theory and disease ecology can aid in identifying both reservoir hosts and species at risk of disease‐driven declines.
Susac syndrome: clinical characteristics and treatment in 29 new cases
Authors: Mateen F. J. , Zubkov A. Y. , Muralidharan R. , Fugate J. E. , Rodriguez F. J. , Winters J. L. , Petty G. W. 
Published: January 2012

Background and purpose:  There are few clinical studies on the attempted treatments and outcomes in patients with Susac syndrome (SS) (retinocochleocerebral vasculopathy).Methods:  A retrospective review was performed of all patients presenting with SS at the Mayo Clinic in Rochester, Minnesota, USA (1 January 1998–1 October 2011).Results:  There were 29 cases of SS (24 women, mean age at presentation, 35 years; range, 19–65; full triad of brain, eye, and ear involvement, n = 16; mean follow‐up time, 29 months). Thirty CSF analyses were performed in 27 cases (mean protein 130 mg/dl, range 35–268; mean cell count 14, range 1–86). MRI of the brain showed corpus callosal involvement (79%), T2‐weighted hyperintensities (93%), and gadolinium enhancement (50%). Average lowest modified Rankin Scale score was 2.5 (median 2, range 0–5). Most patients (93%) received immunosuppressive treatment, with a mean time to treatment of 2 months following symptomatic onset. Treatments included intravenous methylprednisolone or dexamethasone (n = 23), oral corticosteroids (n = 24), plasma exchange (PLEX) (n = 9), intravenous immunoglobulin (IVIg) (n = 15), cyclophosphamide (n = 6), mycophenolate mofetil (n = 5), azathioprine (n = 2), and rituximab (n = 1). Most patients also received an antiplatelet agent (n = 21). Improvement or stabilization was noted in eight of 11 cases treated with IVIg in the acute period (three experienced at least partial deterioration) and eight of nine cases of PLEX treatment (one lost to follow up).Conclusions:  Susac syndrome may be severe, disabling, and protracted in some patients. PLEX may be an adjunct or alternative therapy for patients who do not experience symptomatic improvement following steroid treatment.
The exhausting dilemmas faced by home‐care service providers when enhancing participation among older adults receiving home care
Authors: Vik Kjersti , Eide Arne H. 
Published: January 2012

Scand J Caring Sci; 2012; 26; 528–536The exhausting dilemmas faced by home‐care service providers when enhancing participation among older adults receiving home careOlder adults wish to stay at home, participate in society and manage on their own as long as possible. Many older adults will, however, eventually become dependent on care and help to maintain their daily living. Thus, to enhance activity and participation also among older adults that receive home‐based services, there is a strong need for development of knowledge‐based practice regarding participation. The specific aim of this study is to explore how service providers perceive that their working conditions influence on their possibilities to promote participation among older adults, and more specifically, how they perceive the influence of their working conditions. A purposeful sampling strategy was applied, and six focus groups with professionals in two municipalities were conducted. The focus groups comprised four and six participants of varying ages, length of working experience and professions. A total of 30 service providers participated. The data were analysed by a constant comparative method following the guidelines from Grounded Theory. The analysis identified the categories ‘encountering needs that cannot be met’, ‘expectations about participation’, ‘organisation of services’ and ‘professional standards’ influencing the service delivery. During this analytical process, ‘being on the verge’ emerged as a core category that describes the service providers’ experience of a stressful workday, i.e. when they had the feeling of working against their own professional standards and being pushed to their limits. The findings indicate how the professional standards of service providers on the whole are in line with health policy for in‐home services. Policy objectives are, however, not always followed owing to different constraints at the level of service delivery. Along the path from political ideals to the practical execution of services, external circumstances related to the organisation of services are perceived as crucial.
Identification and characterization of Rhodopseudomonas palustris TIE‐1 hopanoid biosynthesis mutants
Authors: WELANDER P. V. , DOUGHTY D. M. , WU C.‐H. , MEHAY S. , SUMMONS R. E. , NEWMAN D. K. 
Published: January 2012

AbstractHopanes preserved in both modern and ancient sediments are recognized as the molecular fossils of bacteriohopanepolyols, pentacyclic hopanoid lipids. Based on the phylogenetic distribution of hopanoid production by extant bacteria, hopanes have been used as indicators of specific bacterial groups and/or their metabolisms. However, our ability to interpret them ultimately depends on understanding the physiological roles of hopanoids in modern bacteria. Toward this end, we set out to identify genes required for hopanoid biosynthesis in the anoxygenic phototroph Rhodopseudomonas palustris TIE‐1 to enable selective control of hopanoid production. We attempted to delete 17 genes within a putative hopanoid biosynthetic gene cluster to determine their role, if any, in hopanoid biosynthesis. Two genes, hpnH and hpnG, are required to produce both bacteriohopanetetrol and aminobacteriohopanetriol, whereas a third gene, hpnO, is required only for aminobacteriohopanetriol production. None of the genes in this cluster are required to exclusively synthesize bacteriohopanetetrol, indicating that at least one other hopanoid biosynthesis gene is located elsewhere on the chromosome. Physiological studies with the different deletion mutants demonstrated that unmethylated and C30 hopanoids are sufficient to maintain cytoplasmic but not outer membrane integrity. These results imply that hopanoid modifications, including methylation of the A‐ring and the addition of a polar head group, may have biologic functions beyond playing a role in membrane permeability.
Time‐series analysis of two hydrothermal plumes at 9°50′N East Pacific Rise reveals distinct, heterogeneous bacterial populations
Authors: SYLVAN J. B. , PYENSON B. C. , ROUXEL O. , GERMAN C. R. , EDWARDS K. J. 
Published: January 2012

AbstractWe deployed sediment traps adjacent to two active hydrothermal vents at 9°50′N on the East Pacific Rise (EPR) to assess the variability in bacterial community structure associated with plume particles on the timescale of weeks to months, to determine whether an endemic population of plume microbes exists, and to establish ecological relationships between bacterial populations and vent chemistry. Automated rRNA intergenic spacer analysis (ARISA) indicated that there are separate communities at the two different vents and temporal community variations between each vent. Correlation analysis between chemistry and microbiology indicated that shifts in the coarse particulate (>1 mm) Fe/(Fe+Mn+Al), Cu, V, Ca, Al, 232Th, and Ti as well as fine‐grained particulate (<1 mm) Fe/(Fe+Mn+Al), Fe, Ca, and Co are reflected in shifts in microbial populations. 16S rRNA clone libraries from each trap at three time points revealed a high percentage of Epsilonproteobacteria clones and hyperthermophilic Aquificae. There is a shift toward the end of the experiment to more Gammaproteobacteria and Alphaproteobacteria, many of whom likely participate in Fe and S cycling. The particle‐attached plume environment is genetically distinct from the surrounding seawater. While work to date in hydrothermal environments has focused on determining the microbial communities on hydrothermal chimneys and the basaltic lavas that form the surrounding seafloor, little comparable data exist on the plume environment that physically and chemically connects them. By employing sediment traps for a time‐series approach to sampling, we show that bacterial community composition on plume particles changes on timescales much shorter than previously known.
Evaluation of a Four‐drug, Three‐antibiotic, Nonbismuth–containing “Concomitant” Therapy as First‐line Helicobacter pylori Eradication Regimen in Greece
Authors: Georgopoulos Sotirios , Papastergiou Vasilios , Xirouchakis Elias , Laudi Fotini , Papantoniou Nikitas , Lisgos Phillipos , Spiliadi Chariklia , Fragou Paraskevi , Skorda Lamprini , Karatapanis Stylianos 
Published: January 2012

AbstractBackground:  The eradication rates of Helicobacter pylori (H. pylori) with standard treatments are decreasing worldwide as in Greece. Studies with new antibiotic combinations are needed to find better methods of eradication. Therefore, the aim of this study was to evaluate efficacy and tolerability of a 10‐day, four‐drug, three‐antibiotic, nonbismuth–containing concomitant regimen.Materials and Methods:  This is a prospective, open‐label, multicenter study that included 131 patients infected with H. pylori. All patients were diagnosed with peptic ulcer disease or nonulcer dyspepsia by endoscopy. H. pylori infection was established by at least two positive tests among rapid urease test, gastric histology, and 13C‐urea breath test. For 10 days, all patients received esomeprazole 40 mg, amoxycillin 1000 mg, clarithromycin 500 mg, and metronidazole 500 mg, all b.d. eradication was assessed with 13C urea breath test 8 weeks after the start of treatment. Intention‐to‐treat and per‐protocol eradication rates were determined.Results:  One hundred and twenty‐seven of the 131 patients completed the study. At intention‐to‐treat analysis, the eradication rate was 91.6% (95% confidence interval (CI), 85.5–95.7%). For the per‐protocol analysis, the eradication rate was 94.5% (95% CI, 89–97.8%). Adverse events were noted in 42 of 131 (32.1%); drug compliance was excellent with 96.9% of the patients taking more than 90% of the prescribed medication.Conclusion:  A 10‐day concomitant regimen appears to be an effective, safe, and well‐tolerated treatment option for first‐line H. pylori eradication in Greece.
Contingent Claim Pricing Using a Normal Inverse Gaussian Probability Distortion Operator
Authors: Godin Frédéric , Mayoral Silvia , Morales Manuel 
Published: January 2012

AbstractWe consider the problem of pricing contingent claims using distortion operators. This approach was first developed in (Wang, 2000) where the original distortion function was defined in terms of the normal distribution. Here, we introduce a new distortion based on the Normal Inverse Gaussian (NIG) distribution. The NIG is a generalization of the normal distribution that allows for heavier skewed tails. The resulting operator asymmetrically distorts the underlying distribution. Moreover, we show how we can recuperate non‐Gaussian Black–Scholes formulas using distortion operators and we provide illustrations of their performance. We conclude with a brief discussion on risk management applications.
Short Selling Behavior and Mad Money
Authors: Hobbs Jeffrey , Keasler Terrill R. , McNeil Chris R. 
Published: January 2012

AbstractWe examine 1,234 buy recommendations from Jim Cramer's Mad Money television show. Consistent with prior research, we report positive abnormal returns immediately after buy recommendations, followed by a reversal, indicative of an overpricing event. We also find a marked increase in short selling. Our results show a positive association between shorting and the buy recommendations even after controlling for factors shown in the literature to influence shorting. We do not find similar effects after sell recommendations. These results suggest that short sellers act to exploit short‐term overpricing arising from behavioral biases of some investors.
Earnings Announcements: Good News for Institutional Investors and Short Sellers
Authors: Berkman Henk , McKenzie Michael D. 
Published: January 2012

AbstractIn this paper, we consider the trading behavior of institutional investors and short sellers around earnings announcements. The results suggest that institutional investors, and to a lesser extent short sellers, successfully anticipate earnings news. In the period immediately after the earnings announcement, both types of traders are active in the market and trade in response to the earnings announcement. In particular, short sellers are quick to increase their short positions when a company releases bad news. Institutional traders also trade in response to the news; however, they take longer to react.