1,908 research outputs found
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Revision of the Chiapan deer mouse, Peromyscus zarhynchus, with the description of a new species
We analyzed morphometric and molecular variation among 8 populations of Peromyscus zarhynchus grouped into 5 pooled samples representing separate physiographic regions across the range of this species in Chiapas, Mexico, and western Guatemala. Mitochondrial sequence data identify 2 well-supported and reciprocally monophyletic clades, separating all Chiapas specimens from those in Guatemala. These 2 clades group as a strongly supported monophyletic lineage aligned with other members of the Peromyscus mexicanus species group. The Chiapas clade is further subdivided into 4 subclades: 1) samples from the western part of the state, 2) specimens from a single locality in Northern Chiapas, 3) all central localities, and 4) those from a single locality in Eastern Chiapas. The molecular distance in the mitochondrial cytochrome-b gene (Cytb) between the 2 major clades is relatively low (mean p-distance = 3.66%); those between the 4 Chiapas subclades are even less (mean p-distance 2.73%). Multivariate analyses of external and craniodental morphometric variables also distinguish 2 major groups, separating Guatemalan from Chiapas samples but with the latter also divided into 2 subgroups, one that segregates the Northern Chiapas sample from those distributed elsewhere in that state. The Guatemalan and Chiapas samples differ in both cranial size and shape variables. The second-level separation of samples from within Chiapas (northern versus all others) is interpreted to result from the combination of local adaptation to distinct physiographic regions and geographic isolation generated by patches of suitable habitat. We describe the Guatemalan samples as a distinct species based on their molecular and morphological uniqueness, and argue that P. zarhynchus itself is divided into definable subspecies, with the nominotypical form P. z. zarhynchus, restricted to the vicinity of its type locality (TumbalĂĄ) in Northern Chiapas, and P. z. cristobalensis with type locality of San Cristobal, over the remainder of the species range in the state
Reconstructing Coastal Sediment Budgets From Beachâ and ForeduneâRidge Morphology: A Coupled Field and Modeling Approach
Preserved beach and foredune ridges may serve as proxies for coastal change, reflecting alterations in sea level, wave energy, or past sediment fluxes. In particular, timeâvarying shoreface sediment budgets have been inferred from the relative size of foredune ridges through application of radiocarbon and optically stimulated luminescence dating to these systems over the last decades. However, geochronological control requires extensive field investigation and analysis. Purely fieldâbased studies might also overlook relationships between the mechanics of sediment delivery to the shoreface and foredune ridges, missing insights about sensitivity to changes in sediment budget. We therefore propose a simple geomorphic model of beach/foreduneâridge and swale morphology to quantify the magnitude of changes in crossâshore sediment budget, employing field measurements of ridge volume, ridge spacing, elevation, and shoreline progradation. Model behaviors are constrained by the partitioning of sediment fluxes to the shoreface and foredune ridge and can be used to reproduce several crossâshore patterns observed in nature. These include regularly spaced ridges (âwashboardsâ), large singular ridges, and wide swales with poorly developed ridges. We evaluate our model against wellâpreserved ridge and swale systems at two sites along the Virginia Eastern Shore (USA): Fishing Point, for which historical records provide a detailed history of shoreline progradation and ridge growth, and Parramore Island, for which a relatively more complex morphology developed over a poorly constrained period of prehistoric growth. Our results suggest this new model could be used to infer the sensitivity of field sites across the globe to variations in sediment delivery
Elevated CO<sub>2</sub> alleviates high PAR and UV stress in the unicellular Chlorophyte Dunaliella tertiolecta
The effects of increased CO2 and irradiance on the physiological performance of the chlorophyte Dunaliella tertiolecta were studied at different PAR and UVR (UVA+UVB) irradiances, simulating the solar radiation at different depths, under present (390 ppmv, LC) and predicted CO2 levels (1000 ppmv, HC). Cell stress after UVR-exposure was mostly attenuated under HC levels, as evidenced by a decrease in reactive oxygen species accumulation. DNA damage showed a 42-fold increase in cyclobutane-pyrimidine dimers formation under the highest irradiance in LC with respect to the lowest irradiance. Photolyase gene expression was upregulated under HC resulting in a drastic decrease in CPDs accumulation to only 25% with respect to LC. However, the expression of genes related to the replacement of photosynthetic apparatus proteins (PsbA and LHCII) were downregulated at HC compared to LC. Proliferating cell nuclear antigen (PCNA) accumulation was always higher in HC and the accumulation pattern indicated its involvement in DNA repair or growth depending on the irradiance doses. Our results suggest that marine unicellular chlorophytes might possibly become more resilient to UVR exposure under future CO2 regimes.Universidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂa Tech
Combinatorial experimental protocols for Erbicin-derived immunoagents and Herceptin
Erbicin is a human anti-ErbB2 single-chain antibody fragment with high affinity and selectivity for ErbB2-positive cancer cells. Two anti-ErbB2 immunoconjugates, called Erb-hRNase and Erb-hcAb, have been prepared and found to be selectively cytotoxic on ErbB2-positive cancer cells in vitro and vivo. In Erb-hRNase, Erbicin is linked to a human RNase and in Erb-hcAb it is linked to the key structural and functional regions of a human IgG. Herceptin is an anti-ErbB2 humanised antibody successfully used in the immunotherapy of breast cancer. We report here that the Erbicin-derived immunoagents target on breast cancer cells an ErbB2 epitope different than that of Herceptin. This finding led us to verify the effects of Herceptin on breast cancer cells when it was used in combination with the Erbicin-derived immunoagents. The results indicated that in combination experiments the antitumour action of Herceptin and that of the novel agents were significantly increased in an additive fashion. An inspection of the mechanism of action of Erb-hRNase or Erb-hcAb combined with Herceptin provided evidence that the antibody combinations engendered an increased downregulation of the ErbB2 receptor, and led to an enhanced apoptotic cell death
Slepton mass-splittings as a signal of LFV at the LHC
Precise measurements of slepton mass-splittings might represent a powerful
tool to probe supersymmetric (SUSY) lepton flavour violation (LFV) at the LHC.
We point out that mass-splittings of the first two generations of sleptons are
especially sensitive to LFV effects involving transitions. If these
mass-splittings are LFV induced, high-energy LFV processes like the neutralino
decay {\nt}_2\to\nt_1\tau^{\pm}\mu^{\mp} as well as low-energy LFV processes
like are unavoidable. We show that precise slepton
mass-splitting measurements and LFV processes both at the high- and low-energy
scales are highly complementary in the attempt to (partially) reconstruct the
flavour sector of the SUSY model at work. The present study represents another
proof of the synergy and interplay existing between the LHC, i.e. the {\em
high-energy frontier}, and high-precision low-energy experiments, i.e. the {\em
high-intensity frontier}.Comment: 11 pages, 5 figures. v2: added discussion on backgrounds, added
references, version to be published on JHE
Observational Study Design in Veterinary Pathology, Part 1: Study Design
Observational studies are the basis for much of our knowledge of veterinary pathology and are highly relevant to the daily practice of pathology. However, recommendations for conducting pathology-based observational studies are not readily available. In part 1 of this series, we offer advice on planning and conducting an observational study with examples from the veterinary pathology literature. Investigators should recognize the importance of creativity, insight, and innovation in devising studies that solve problems and fill important gaps in knowledge. Studies should focus on specific and testable hypotheses, questions, or objectives. The methodology is developed to support these goals. We consider the merits and limitations of different types of analytic and descriptive studies, as well as of prospective vs retrospective enrollment. Investigators should define clear inclusion and exclusion criteria and select adequate numbers of study subjects, including careful selection of the most appropriate controls. Studies of causality must consider the temporal relationships between variables and the advantages of measuring incident cases rather than prevalent cases. Investigators must consider unique aspects of studies based on archived laboratory case material and take particular care to consider and mitigate the potential for selection bias and information bias. We close by discussing approaches to adding value and impact to observational studies. Part 2 of the series focuses on methodology and validation of methods
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Visual analysis design to support research into movement and use of space in Tallinn: A case study
We designed and applied interactive visualisation to help an urban study group investigate how suburban residents in the Tallinn Metropolitan Area (Estonia) use space in the city. We used mobile phone positioning data collected from suburban residents together with their socio-economic characteristics. Land-use data provided geo-context that helped characterise visited locations by suburban residents. Our interactive visualisation design was informed by a set of research questions framed as identification, localisation and comparison tasks. The resulting prototype offers five linked and coordinated views of spatial, temporal, socio-economic characteristics and land-use aspects of data. Brushing, sorting and filtering provide visual means to identify similarities between individuals and facilitate the identification, localisation and comparison of patterns of use of urban space. The urban study group was able to use the prototype to explore their data and address their research questions in a more flexible way than previously possible. Initial feedback was positive. The prototype was found to support the research and facilitate the discovery of patterns and relations among groups of participants and their movements
A screen-printed paper microbial fuel cell biosensor for detection of toxic compounds in water
Access to safe drinking water is a human right, crucial to combat inequalities, reduce poverty and allow sustainable development. In many areas of the world, however, this right is not guaranteed, in part because of the lack of easily deployable diagnostic tools. Low-cost and simple methods to test water supplies onsite can protect vulnerable communities from the impact of contaminants in drinking water. Ideally such devices would also be easy to dispose of so as to leave no trace, or have a detrimental effect on the environment. To this aim, we here report the first paper microbial fuel cell (pMFC) fabricated by screen-printing biodegradable carbon-based electrodes onto a single sheet of paper, and demonstrate its use as a shock sensor for bioactive compounds (e.g. formaldehyde) in water. We also show a simple route to enhance the sensor performance by folding back-to-back two pMFCs electrically connected in parallel. This promising proof of concept work can lead to a revolutionizing way of testing water at point of use, which is not only green, easy-to-operate and rapid, but is also affordable to all
Effect of the topical administration of corticosteroids and tuberculin pre-sensitisation on the diagnosis of tuberculosis in goats
Background: Caprine tuberculosis (TB) is a zoonosis caused by members of the Mycobacterium tuberculosis complex (MTBC). Caprine TB control and eradication programmes have traditionally been based on intradermal tuberculin tests and slaughterhouse surveillance. However, this strategy has limitations in terms of sensitivity and specificity. Different factors may affect the performance of the TB diagnostic tests used in goats and, subsequently, the detection of TB-infected animals. In the present study, the effect of two of the factors that may affect the performance of the techniques used to diagnose TB in goats, the topical administration of corticosteroids and a recent pre-sensitisation with tuberculin, was analysed. Methods: The animals (n = 151) were distributed into three groups: (1) a group topically treated with corticosteroids 48 h after intradermal tuberculin tests (n = 53); (2) a group pre-sensitised with bovine and avian purified protein derivatives (PPDs) 3 days before the intradermal tuberculin test used for TB diagnosis (n = 48); and (3) a control group (n = 50). All the animals were tested using single and comparative intradermal tuberculin (SIT and CIT, respectively) tests, an interferon-gamma release assay (IGRA) and a P22 ELISA. Results: The number of SIT test reactors was significantly lower in the group treated with corticosteroids when compared to the pre-sensitised (p 0.05). No significant effect was observed on IGRA and P22 ELISA due to corticosteroids administration. Nevertheless, a previous PPD injection affected the IGRA performance in some groups. Conclusions: The application of topical corticosteroid 24 h before reading the SIT and CIT tests can reduce the increase in skin fold thickness and subsequently significantly decrease the number of positive reactors. Corticosteroids used can be detected in hair samples. A previous pre-sensitisation with bovine and avian PPDs does not lead to a significant reduction in the number of intradermal tests reactors. These results are valuable in order to improve diagnosis of caprine TB and detect fraudulent activities in the context of eradication programs.This study was funded by the âAnalysis of the long-term caprine tuberculosis eradication process and development of diagnostic tests and control measures for its improvement (GoaTBfree-UCM)â Project (PID2019-105155RB-C31, Ministry of Science and Innovation of Spain) and the Ministry of Agriculture, Fisheries and Food of Spain. JO was supported by an FPU contract-fellowship (FormaciĂłn de Profesorado Universitario) from the Spanish Ministerio de Ciencia, InnovaciĂłn y Universidades (FPU18/05197).S
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