bluuebunny/crossref_metadata_2025 huggingface dataset:
Tracking prospecting movements involved in breeding habitat selection: insights, pitfalls and perspectives
Authors: Ponchon Aurore , Grémillet David , Doligez Blandine , Chambert Thierry , Tveraa Torkild , González‐Solís Jacob , Boulinier Thierry
Published: November 2012

Prospecting allows individuals to gather information on the local quality of potential future breeding sites. In a variable and heterogeneous environment, it plays a major role in breeding habitat selection and potentially helps individuals make optimal dispersal decisions. Although prospecting movements, involving visits to other breeding sites, have been observed in many species at relatively fine spatial scales, little is known about their occurrence at larger scales. Furthermore, the adaptive value of dispersal strategies in response to environmental changes remains poorly investigated.

Here, our main objective is to highlight in what ways tracking devices could constitute powerful tools to study prospecting behaviour at various spatial scales. First, we stress the importance of considering prospecting movements involved in breeding habitat selection and we detail the type of data that can be collected. Then, we review the advantages and constraints associated with the use of tracking devices in this context, and we suggest new perspectives to investigate the behavioural strategies adopted by individuals during breeding habitat selection processes and dispersal decisions.

The rapid development of new powerful electronic tools for tracking individual behaviour thus opens a wide range of opportunities. More specifically, it may allow a more thorough understanding of the role of scale‐dependent dispersal behaviour in population responses to environmental changes.
A stepwise‐selected spline approximation to time‐varying parameters, with application to occupancy modelling
Authors: Thorson James T. , Zhou Shijie , Punt André E. , Smith Anthony D. M.
Published: November 2012

Many population dynamics models and common software packages, including for capture–mark–recapture, occupancy and catch‐at‐age models, are estimable using parameters that are either constant for all years or vary annually.

We develop a spline approximation to time‐varying parameters, which includes the constant or annually varying case as two extremes, where the Akaike Information Criterion is used to select an appropriate degree of smoothness, ranging from change in every year to no change at all. Simulation modelling is used to evaluate the performance of this method relative to constant, annually varying, or random‐effect parameter estimates when applied to an occupancy model that simultaneously estimates abundance and detectability in multiple sampling strata. We also demonstrate this method by approximating time‐varying abundance using 25 years of detection/non‐detection data for 42 Chondrichthyes species off northern Australia.

Simulation modelling indicates that the stepwise‐spline approximation results in lower estimation errors for the proportion of abundance in each stratum, regardless of sample sizes, the underlying form for time‐varying abundance and the inclusion of unmodelled process errors.

Applied to the Chondrichthyes data from northern Australia, the spline approximation identifies temporal variability in abundance for 34 of 42 species, and an annually varying model is never selected.

We recommend this stepwise‐spline approximation in cases where a decision is necessary between constant or annually varying forms for an estimated parameter. Possible applications include occupancy, capture–mark–recapture, catch‐at‐age and index standardization models.
Phase Transition Behavior and Large Piezoelectricity Near the Morphotropic Phase Boundary of Lead‐Free (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 Ceramics
Authors: Tian Ye , Wei Lingling , Chao Xiaolian , Liu Zonghuai , Yang Zupei
Published: November 2012

The phase transition behavior and piezoelectric properties of (Ba1−xCax)(Zr0.1Ti0.9)O3 and (Ba0.85Ca0.15)(ZryTi1−y)O3 ceramics were investigated in this work to find out the potential factors contributing to large piezoelectricity. It was found that the morphotropic phase boundary (MPB) of (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 ceramics was closely related to the presence of an intermediate phase (considered as orthorhombic phase in this work) between rhombohedral (R) and tetragonal (T) phases at a narrow region, which could be carefully adjusted by the temperature and contents of Ca and Zr in the composition. In addition, the maximum piezoelectric and electromechanical coupling coefficients (with d33 = 572 pC/N and kp = 0.57) were observed near the MPB region close to T phase side, which might be intimately related to the presence of the intermediate phase. This investigation yielded a new sight to understand the mechanism of enhanced piezoelectricity near the MPB.
0.40% Bipolar Strain in Lead Free BNT–KNN System Modified with Li,Ta and Sb
Authors: Singh Amrita , Chatterjee Ratnamala
Published: November 2012

In this work we demonstrate a large electric field‐induced bipolar strain ~0.40% in Li, Ta and Sb modified BNT–KNN ((1−x) Bi0.5Na0.5TiO3–xK0.47Na0.47Li0.06 Nb0.74Sb0.06Ta0.2O3) system. The morphotropic phase boundary (MPB) of the system between rhombohedral and tetragonal phases lies in the range 0.02 ≤ x ≤ 0.06, beyond which all compositions (up to x < 0.15) were found to be tetragonal. A clear trade‐off between the large strain values and achievable d33, kp for a particular composition was noted. It is shown that while for x = 0.03, d33 169 pC/N, kp 49% and strain ~0.13% were obtained, for x = 0.08 with 0.40% strain, d33 and kp values decreased drastically.
Preparation of Nickel Ferrite–Copper Composite by Pressureless Infiltration
Authors: Tao Yuqiang , Li Zhiyou , Zhang Lei , Gan Xueping , Zhou Kechao
Published: November 2012

Pressureless infiltration was used to prepare a dense Cu/NiFe2O4–10NiO composite with interlocking microstructure. The results showed that the addition of Cu2O in Cu could improve the wettability between Cu and NiFe2O4. The metallic phase content and densification of the resulting composite were 34 wt% and 99.2%, respectively. The resulting composite had a flexural strength of 200 ± 20 MPa, a room‐temperature thermal diffusivity of 0.12 cm2/s, and an electrical conductivity of 1503 S/cm at 900°C.
Dual origin, development, and fate of bovine pancreatic islets
Authors: Merkwitz Claudia , Lochhead Paul , Böttger Jan , Matz‐Soja Madlen , Sakurai Michiharu , Gebhardt Rolf , Ricken Albert M.
Published: November 2012

Endocrine cells are evident at an early stage in bovine pancreatic development when the pancreas still consists of primitive epithelial cords. At this stage, the endocrine cells are interspersed between the precursor cells destined to form the ductulo‐acinar trees of later exocrine lobules. We here demonstrate that, in bovine fetuses of crown rump length ≥ 11 cm, the endocrine cells become increasingly segregated from the developing exocrine pancreas by assembly into two units that differ in histogenesis, architecture, and fate. Small numbers of ‘perilobular giant islets’ are distinguishable from larger numbers of ‘intralobular small islets’. The two types of islets arise in parallel from the ends of the ductal tree. Aside from differences in number, location, and size, the giant and small islets differ in cellular composition (predominantly insulin‐synthesising cells vs. mixtures of endocrine cells), morphology (epithelial trabeculae with gyriform and rosette‐like appearance vs. compact circular arrangements of endocrine cells), and in their relationships to intrapancreatic ganglia and nerves. A further difference becomes apparent during the antenatal period; while the ‘interlobular small islets’ persist in the pancreata of calves and adult cattle, the perilobular giant islets are subject to regression, characterised by involution of the parenchyma, extensive haemorrhage, leukocyte infiltration (myeloid and T‐cells) and progressive fibrotic replacement. In conclusion, epithelial precursor cells of the ductolo‐acinar tree may give rise to populations of pancreatic islets with different histomorphology, cellular composition and fates. This should be taken into account when using these cells for the generation of pancreatic islets for transplantation therapy.
The attitudes of undergraduate nursing students towards mental health nursing: a systematic review
Authors: Happell Brenda , Gaskin Cadeyrn J
Published: November 2012

Aims and objectives

To present the findings of a systematic review on (1) the attitudes of undergraduate nursing students towards mental health nursing and (2) the influence of undergraduate nursing education on the attitudes of undergraduate nursing students towards mental health nursing.

Background

Recruitment and retention of mental health nurses is challenging. Undergraduate nursing students' attitudes towards mental health nursing may influence whether they choose to practice in this specialty upon graduation.

Design

A systematic review.

Method

Searches of the CINAHL, MEDLINE and PsycINFO electronic databases returned 1400 records, of which 17 met the inclusion criteria for this review. A further four papers were obtained through scanning the reference lists of those articles included from the initial literature search.

Results

Research on the attitudes of undergraduate nursing students towards mental health nursing has consistently shown that mental health is one of the least preferred areas of nursing for a potential career. With respect to the influence of undergraduate nursing education on the attitudes of students towards mental health nursing, quasi‐experimental studies have generally demonstrated that students tended to have more favourable attitudes towards mental health nursing when they had received more hours of theoretical preparation and undertaken longer clinical placements.

Conclusion

Many nursing students regard mental health nursing as the least preferred career option. Education, via classroom teaching and clinical placements, seems to engender more positive attitudes towards mental health nursing. There is no evidence, however, that changing student attitudes results in more graduates beginning careers in mental health nursing.

Reference to clinical practice

The constancy of negative attitudes to mental health nursing over time suggests the focus of research should shift. Clinicians have the capacity to promote a more positive view of mental health nursing. This requires further exploration.
Can the Augmented Solow Model with Migration Explain the Italian Internal Brain Drain?
Authors: Piras Romano
Published: November 2012

We extend the Dolado et al. (1994) model to both inflows and outflows of migrants and assume that they have a human capital endowment that contributes to increase/decrease the stock of human capital in the receiving/sending economy. We derive the conditional convergence equation in which the impact of migration flows on the growth rate is disentangled in a pure quantity effect and in a quality or composition effect of immigration and emigration rates that accounts for the relative human capital endowment of migrants with respect to resident population. Next, we test the model with Italian regional data for the 1970–2005 time period. We find that the model provides a good explanation of the Italian experience. The quantity effect is negative for the immigration rate and positive for the emigration rate, whereas the composition effect is positive for immigration and negative for emigration. Finally, we separate the centre‐north from the south and find that the composition effect of emigration is stronger for the latter. We interpret these results as a clear evidence of a brain drain from the Mezzogiorno to the centre‐northern regions.
Export of the pneumococcal phage SV1 lysin requires choline‐containing teichoic acids and is holin‐independent
Authors: Frias Maria João , Melo‐Cristino José , Ramirez Mário
Published: November 2012

Streptococcus pneumoniae bacteriophages (phages) rely on a holin–lysin system to accomplish host lysis. Due to the lack of lysin export signals, it is assumed that holin disruption of the cytoplasmic membrane allows endolysin access to the peptidoglycan. We investigated the lysis mechanism of pneumococcal phage SV1, by using lysogens without holin activity. Upon phage induction in a holin deficient background, phage lysin was gradually targeted to the cell wall, in spite of lacking any obvious signal sequence. Our data indicate that export of the phage lysin requires the presence of choline in the teichoic acids, an unusual characteristic of pneumococci. At the bacterial surface, the exolysin remains bound to choline residues without inducing lysis, but is readily activated by the collapse of the membrane potential. Additionally, the activation of the major autolysin LytA, which also participates in phage‐mediated lysis, is equally related to perturbations of the membrane proton motive force. These results indicate that collapse of the membrane potential by holins is sufficient to trigger bacterial lysis. We found that the lysin of phage SV1 reaches the peptidoglycan through a novel holin‐independent pathway and propose that the same mechanism could be used by other pneumococcal phages.
First cloning and characterization of two functional aquaporin genes from an arbuscular mycorrhizal fungus Glomus intraradices
Authors: Li Tao , Hu Ya‐Jun , Hao Zhi‐Peng , Li Hong , Wang You‐Shan , Chen Bao‐Dong
Published: November 2012

Arbuscular mycorrhizal (AM) symbiosis is known to stimulate plant drought tolerance. However, the molecular basis for the direct involvement of AM fungi (AMF) in plant water relations has not been established.

Two full‐length aquaporin genes, namely GintAQPF1 and GintAQPF2, were cloned by rapid amplification of cDNA 5′‐ and 3′‐ends from an AMF, Glomus intraradices. Aquaporin localization, activities and water permeability were examined by heterologous expression in yeast. Gene expression during symbiosis was also analyzed by quantitative real‐time polymerase chain reaction.

GintAQPF1 was localized to the plasma membrane of yeast, whereas GintAQPF2 was localized to both plasma and intracellular membranes. Transformed yeast cells exhibited a significant decrease in cell volume on hyperosmotic shock and faster protoplast bursting on hypo‐osmotic shock. Polyethylene glycol (PEG) stimulated, but glycerol inhibited, the aquaporin activities. Furthermore, the expression of the two genes in arbuscule‐enriched cortical cells and extraradical mycelia of maize roots was also enhanced significantly under drought stress.

GintAQPF1 and GintAQPF2 are the first two functional aquaporin genes from AMF reported to date. Our data strongly support potential water transport via AMF to host plants, which leads to a better understanding of the important role of AMF in plant drought tolerance.
Identification and characterization of MYB‐bHLH‐WD40 regulatory complexes controlling proanthocyanidin biosynthesis in strawberry (Fragaria × ananassa) fruits
Authors: Schaart Jan G. , Dubos Christian , Romero De La Fuente Irene , van Houwelingen Adèle M. M. L. , de Vos Ric C. H. , Jonker Harry H. , Xu Wenjia , Routaboul Jean‐Marc , Lepiniec Loïc , Bovy Arnaud G.
Published: November 2012

Strawberry (Fragaria × ananassa) fruits contain high concentrations of flavonoids. In unripe strawberries, the flavonoids are mainly represented by proanthocyanidins (PAs), while in ripe fruits the red‐coloured anthocyanins also accumulate. Most of the structural genes leading to PA biosynthesis in strawberry have been characterized, but no information is available on their transcriptional regulation. In Arabidopsis thaliana the expression of the PA biosynthetic genes is specifically induced by a ternary protein complex, composed of AtTT2 (AtMYB123), AtTT8 (AtbHLH042) and AtTTG1 (WD40‐repeat protein).

A strategy combining yeast‐two‐hybrid screening and agglomerative hierarchical clustering of transcriptomic and metabolomic data was undertaken to identify strawberry PA regulators.

Among the candidate genes isolated, four were similar to AtTT2, AtTT8 and AtTTG1 (FaMYB9/FaMYB11, FabHLH3 and FaTTG1, respectively) and two encode putative negative regulators (FaMYB5 and FabHLH3∆). Interestingly, FaMYB9/FaMYB11, FabHLH3 and FaTTG1 were found to complement the tt2‐1, tt8‐3 and ttg1‐1 transparent testa mutants, respectively. In addition, they interacted in yeast and activated the Arabidopsis BANYULS (anthocyanidin reductase) gene promoter when coexpressed in Physcomitrella patens protoplasts.

Taken together, these results demonstrated that FaMYB9/FaMYB11, FabHLH3 and FaTTG1 are the respective functional homologues of AtTT2, AtTT8 and AtTTG1, providing new tools for modifying PA content and strawberry fruit quality.
Variation in carbon availability, defense chemistry and susceptibility to fungal invasion along the stems of mature trees
Authors: Goodsman Devin W. , Lusebrink Inka , Landhäusser Simon M. , Erbilgin Nadir , Lieffers Victor J.
Published: November 2012

If carbon (C) sinks withdraw carbohydrates as they are transported along tree stems, carbohydrate availability may depend on local sink strength and distance from sources. Defenses, including monoterpenes – a major component of resin – limit the invasibility of pines. Since carbohydrate reserves fund monoterpene synthesis, we hypothesized that monoterpene concentrations in pine stems would decrease from the crown to the lower stem, and susceptibility to fungal infection would increase.

Here, we measured carbohydrate and monoterpene concentrations along the stems of lodgepole pine trees (Pinus contorta var. latifolia) before inoculating with a blue‐stain fungus at different heights. After 6 wk, we assessed tree responses to fungal infection based on lesion length and carbohydrate mobilization.

Concentrations of carbohydrates and monoterpenes in the phloem before inoculation decreased with distance from the crown, whereas lesion lengths after inoculation increased. However, trees mobilized sugars in response to fungal infection such that carbohydrate reserves near lesions were similar at all heights.

Despite C mobilization, the lower stem was more vulnerable than the upper stem. Consistent with predictions based on sink–source relationships, vulnerability occurred where carbohydrates were less available, and likely resulted from C withdrawal by sinks higher in the supply chain.
Influence of genetic background and plant age on expression of the potato late blight resistance gene Rpi‐phu1 during incompatible interactions with Phytophthora infestans
Authors: Śliwka J. , Świątek M. , Tomczyńska I. , Stefańczyk E. , Chmielarz M. , Zimnoch‐Guzowska E.
Published: November 2012

The goal of this study was to determine the expression profile of a late blight resistance gene, Rpi‐phu1, after challenge with an incompatible Phytophthora infestans isolate. Relative expression levels were measured by quantitative real‐time PCR, before as well as 1, 3 and 5 days after contact with the pathogen. Plants tested included diploid and tetraploid breeding lines with the gene in different genetic backgrounds and plants of a chosen breeding line at different developmental stages. All tested potato breeding lines with the Rpi‐phu1 gene were highly resistant to P. infestans and so was the line tested at different developmental stages. No significant changes were detected in Rpi‐phu1 transcript level after pathogen challenge in any of the tested tetraploid potato lines. However, Rpi‐phu1 transcription in diploid lines was enhanced by contact with P. infestans. Basal expression of the Rpi‐phu1 gene was significantly lower in the youngest, 3‐week‐old plants than in 6‐week‐old plants. Nevertheless, 1 day after inoculation with the pathogen, transcript levels in these plants were slightly greater than in 6‐week‐old plants, indicating that plant age can influence transcription of the Rpi‐phu1 gene, but that this does not affect late blight resistance.
UV‐B impairs growth and gas exchange in grapevines grown in high altitude
Authors: Berli Federico J. , Alonso Rodrigo , Bressan‐Smith Ricardo , Bottini Rubén
Published: November 2012

We previously demonstrated that solar ultraviolet‐B (UV‐B) radiation levels in high altitude vineyards improve berry quality in Vitis vinifera cv. Malbec, but also reduce berry size and yield, possibly as a consequence of increased oxidative damage and growth reductions (lower photosynthesis). The defense mechanisms toward UV‐B signal and/or evoked damage promote production of antioxidant secondary metabolites instead of primary metabolites. Purportedly, the UV‐B effects will depend on tissues developmental stage and interplay with other environmental conditions, especially stressful situations. In this work, grapevines were exposed to high solar UV‐B (+UV‐B) and reduced (by filtering) UV‐B (−UV‐B) treatments during three consecutive seasons, and the effects of UV‐B, developmental stages and seasons on the physiology were studied, i.e. growth, tissues morphology, photosynthesis, photoprotective pigments, proline content and antioxidant capacity of leaves. The +UV‐B reduced photosynthesis and stomatal conductance, mainly through limitation in gas exchange, reducing plant's leaf area, net carbon fixation and growth. The +UV‐B augmented leaf thickness, and also the amounts of photoprotective pigments and proline, thereby increasing the antioxidant capacity of leaves. The defense mechanisms triggered by + UV‐B reduced lipid peroxidation, but they were insufficient to protect the photosynthetic pigments per leaf dry weight basis. The +UV‐B effects depend on tissues developmental stage and interplay with other environmental conditions such as total radiation and air temperatures.
The Akt–FoxO3a–manganese superoxide dismutase pathway is involved in the regulation of oxidative stress in diabetic nephropathy
Authors: Lu Qian , Zhai Yunpeng , Cheng Qian , Liu Yaowu , Gao Xing , Zhang Ting , Wei Yaqin , Zhang Fan , Yin Xiaoxing
Published: November 2012

New Findings

What is the central question of this study?

Oxidative stress is known to play an important role in the development and progression of diabetic nephropathy. However, the mechanism of overproduction of reactive oxygen species (ROS) in high‐glucose conditions is not completely clear.

What is the main finding and its importance?

We demonstrated that high‐glucose concentrations induced excessive production of ROS and stimulated the phosphoinositide 3‐kinase–Akt–FoxO3a signalling pathway via the upregulation of transforming growth factor‐β1, resulting in phosphorylation and inactivation of FoxO3a and a reduction in the expression of its target gene, FoxO3a‐dependent manganese superoxide dismutase, and then further excessive production of ROS.

Oxidative stress has been shown to play an important role in the development and progression of diabetic nephropathy, and the formation of reactive oxygen species (ROS) is a direct consequence of hyperglycaemia. We hypothesized that hyperglycaemia‐induced ROS can activate the transforming growth factor‐β1 (TGF‐β1)–phosphoinositide 3‐kinase (PI3K)–Akt–FoxO3a signalling pathway, negatively regulating expression of manganese superoxide dismutase (MnSOD), which promotes excessive ROS generation and accelerates the pathological process of diabetic nephropathy. In vitro, in rat mesangial cells, high glucose (30 mmol l−1), but not equimolar mannitol, stimulated ROS production, upregulated the levels of TGF‐β1, increased the phosphorylated Akt/total Akt and phosphorylated FoxO3a/total FoxO3a protein ratios, altered the subcellular localization of FoxO3a and reduced the levels of MnSOD expression. These high‐glucose‐induced changes further promoted the generation of ROS. In vivo, in db/db mice treated with an inhibitor of TGF‐β1 (SB431542) or PI3K (LY294002), the levels of phosphorylated Akt and phosphorylated FoxO3a in the kidney cortices were decreased, the level of MnSOD expression was increased and the level of the lipid peroxidation end‐product, malondialdehyde, was reduced. We conclude that overproduction of ROS induced by a high glucose concentration decreases the expression of MnSOD via the PI3K–Akt–FoxO3a pathway and further aggravates oxidative stress in diabetic nephropathy.
Mock Circulatory Loop Compliance Chamber Employing a Novel Real-Time Control Process
Authors: Taylor Charles E. , Miller Gerald E.
Published: November 2012

The use of compliance chambers in mock circulatory loop construction is the predominant means of simulating arterial compliance. Utilizing mock circulatory loops as bench test methods for cardiac assist technologies necessitates that they must be capable of reproducing the circulatory conditions that would exist physiologically. Of particular interest is the ability to determine instantaneous compliance of the system, and the ability to change the compliance in real-time. This capability enables continuous battery testing of conditions without stopping the flow to change the compliance chamber settings, and the simulation of dynamic changes in arterial compliance. The method tested involves the use of a compliance chamber utilizing a circular natural latex rubber membrane separating the fluid and air portions of the device. Change in system compliance is affected by the airspace pressure, which creates more reaction force at the membrane to the fluid pressure. A pressure sensor in the fluid portion of the chamber and a displacement sensor monitoring membrane center deflection allow for real-time inputs to the control algorithm. A predefined numerical model correlates the displacement sensor data to the volume displacement of the membrane. The control algorithm involves a tuned π loop maintaining the volume distention of the membrane via regulation of the air space pressure. The proportional integral (PI) controller tuning was achieved by creating a computational model of the compliance chamber using Simulink™ Simscape® toolboxes. These toolboxes were used to construct a model of the hydraulic, mechanical, and pneumatic elements in the physical design. Parameter Estimation™ tools and Design Optimization™ methods were employed to determine unknown physical parameters in the system, and tune the process controller used to maintain the compliance setting. It was found that the resulting control architecture was capable of maintaining compliance along a pressure-volume curve and allowed for changes to the compliance set point curve without stopping the pulsatile flow.
Porphyry-Copper Ore Shells Form at Stable Pressure-Temperature Fronts Within Dynamic Fluid Plumes
Authors: Weis P. , Driesner T. , Heinrich C. A.
Published: November 2012

Earning a High Grade

Most of the world's copper and molybdenum come from porphyry-type ore deposits in Earth's crust. The metals are deposited either as veins of concentrated metals in fractured rock or in a confined shell, associated with the edges of magma chamber plumes. But it remains unclear why a front of sharp temperature-pressure gradients, which allows the accumulation of high-grade metal deposits, remains stable.

Weis
et al.

(p.
1613
, published online 15 November; see the Perspective by

Ingebritsen

) constructed a hydrothermal model of a porphyry-type system given a supply of magmatic fluids with high metal concentrations. The thermodynamic properties of injected volatile fluids and dynamic variations in host rock permeability, driven by injection-induced fracturing, controlled the stability and evolution of the fronts and allowed for the formation of an extensive network of ore veins from within the magmatic chamber.
Alignment of Magnetized Accretion Disks and Relativistic Jets with Spinning Black Holes
Authors: McKinney Jonathan C. , Tchekhovskoy Alexander , Blandford Roger D.
Published: November 2012

Black Hole Alignment

In interpreting observations of black holes, it is important to assess the extent to which the accretion disks around black holes and the jets that they produce align with the spin of the black hole. Based on numerical simulations of magnetohydrodynamic fluid flows around rotating black holes,

McKinney
et al.

(p.
49
, published online 15 November) describe a previously unknown mechanism that acts to align the accretion disk and jet with the spin axis of black holes. Unlike previous mechanisms, this effect applies to thick disks, like the one thought to exist around the massive black hole at the center of our galaxy.
Mesenchymal Stem Cells Regulate Blood-Brain Barrier Integrity Through TIMP3 Release After Traumatic Brain Injury
Authors: Menge Tyler , Zhao Yuhai , Zhao Jing , Wataha Kathryn , Gerber Michael , Zhang Jianhu , Letourneau Phillip , Redell John , Shen Li , Wang Jing , Peng Zhalong , Xue Hasen , Kozar Rosemary , Cox Charles S. , Khakoo Aarif Y. , Holcomb John B. , Dash Pramod K. , Pati Shibani
Published: November 2012

The matrix metalloproteinase inhibitor TIMP3 mediates the beneficial effects of mesenchymal stem cells on the blood-brain barrier of the injured mouse brain.
Carriage and Fecal Counts of Cefotaxime M-Producing Escherichia coli in Pigs: a Longitudinal Study
Authors: Hansen Katrine Hartung , Damborg Peter , Andreasen Margit , Nielsen Søren Saxmose , Guardabassi Luca
Published: November 2012

Current knowledge on extended-spectrum beta-lactamases (ESBLs) in animals is based largely on cross-sectional studies and qualitative data. The aim of this longitudinal study was to elucidate carriage proportions and fecal counts of ESBL-producing
Escherichia coli
in pigs during the production cycle. At each of three ESBL-positive single-sited farrow-to-finisher pig farms (farms A, B, and C) included in the study, individual fecal samples were taken from 17 to 20 sows 1 week before farrowing and from 2 piglets of each sow's litter four times from birth to slaughter (as piglets, weaners, and finishers). Cefotaxime (CTX)-resistant coliforms in feces were counted on MacConkey agar containing 2 μg/ml CTX and characterized for the presence of ESBL-encoding genes by PCR and sequencing. CTX-M-positive pigs were detected in all age groups at farms A (
bla
CTX-M-9
group, compatible with
bla
CTX-M-14/17
) and B (
bla
CTX-M-1
group, compatible with
bla
CTX-M-1/61
), whereas only three weaners were positive at farm C (
bla
CTX-M-1
group, compatible with
bla
CTX-M-1/61
). A significant decrease in carriage was detected during the production cycle, with on average 50% carriage immediately after birth, 58% just before weaning, 29% during weaning, and 12% during finishing. The observed reduction in numbers of CTX-M-positive pigs was accompanied by a significant reduction in mean fecal counts of CTX-resistant coliforms from ∼10
7
CFU/g in piglets to ∼10
3
CFU/g in finishers (
P
< 0.001). These findings provide novel information about the epidemiology of ESBLs at the farm level and have important implications for assessments of risks of meat contamination during slaughter.
Characterization of Newcastle Disease Viruses in Wild and Domestic Birds in Luxembourg from 2006 to 2008
Authors: Snoeck Chantal J. , Marinelli Marianna , Charpentier Emilie , Sausy Aurélie , Conzemius Tom , Losch Serge , Muller Claude P.
Published: November 2012

Newcastle disease virus (NDV) is one of the most important viral diseases of birds. Wild birds constitute a natural reservoir of low-virulence viruses, while poultry are the main reservoir of virulent strains. Exchange of virus between these reservoirs represents a risk for both bird populations. Samples from wild and domestic birds collected between 2006 and 2010 in Luxembourg were analyzed for NDV. Three similar avirulent genotype I strains were found in ducks during consecutive years, suggesting that the virus may have survived and spread locally. However, separate introductions cannot be excluded, because no recent complete F gene sequences of genotype I from other European countries are available. Detection of vaccine-like strains in wild waterbirds suggested the spread of vaccine strains, despite the nonvaccination policy in Luxembourg. Among domestic birds, only one chicken was positive for a genotype II strain differing from the LaSota vaccine and exhibiting a so-far-unrecognized fusion protein cleavage site of predicted low virulence. Three genotype VI strains from pigeons were the only virulent strains found. The circulation of NDV in wild and free-ranging domestic birds warrants continuous surveillance because of increased concern that low-virulence wild-bird viruses could become more virulent in domestic populations.
Molecular Analysis of Human and Canine Staphylococcus aureus Strains Reveals Distinct Extended-Host-Spectrum Genotypes Independent of Their Methicillin Resistance
Authors: Vincze S. , Stamm I. , Monecke S. , Kopp P. A. , Semmler T. , Wieler L. H. , Lübke-Becker A. , Walther B.
Published: November 2012

Staphylococcus aureus
causes a wide range of infectious diseases in humans and various animal species. Although presumptive host-specific factors have been reported, certain genetic lineages seem to lack specific host tropism, infecting a broad range of hosts. Such Extended-Host-Spectrum Genotypes (EHSGs) have been described in canine infections, caused by common regional human methicillin-resistant
S. aureus
(MRSA) lineages. However, information is scarce about the occurrence of methicillin-susceptible
S. aureus
(MSSA) EHSGs. To gain deeper insight into EHSG MSSA and EHSG MRSA of human and canine origin, a comparative molecular study was carried out, including a convenience sample of 120 current
S. aureus
(70 MRSA and 50 MSSA) isolates obtained from infected dogs.
spa
typing revealed 48 different
spa
types belonging to 16 different multilocus sequence typing clonal complexes (MLST-CCs). Based on these results, we further compared a subset of canine (
n
= 48) and human (
n
= 14) strains, including isolates of clonal complexes CC5, CC22, CC8, CC398, CC15, CC45, and CC30 by macrorestriction (pulsed-field gel electrophoresis [PFGE]) and DNA-microarray analysis. None of the methods employed was able to differentiate between clusters of human and canine strains independently of their methicillin resistance. In contrast, DNA-microarray analysis revealed 79% of the 48 canine isolates as carriers of the bacteriophage-encoded human-specific immune evasion cluster (IEC). In conclusion, the high degree of similarity between human and canine
S. aureus
strains regardless of whether they are MRSA or MSSA envisions the existence of common genetic traits that enable these strains as EHSGs, challenging the concept of resistance-driven spillover of MRSA.
Nontuberculous Mycobacteria, Fungi, and Opportunistic Pathogens in Unchlorinated Drinking Water in the Netherlands
Authors: van der Wielen Paul W. J. J. , van der Kooij Dick
Published: November 2012

The multiplication of opportunistic pathogens in drinking water supplies might pose a threat to public health. In this study, distributed unchlorinated drinking water from eight treatment plants in the Netherlands was sampled and analyzed for fungi, nontuberculous mycobacteria (NTM), and several opportunistic pathogens by using selective quantitative PCR methods. Fungi and NTM were detected in all drinking water samples, whereas
Legionella pneumophila
,
Pseudomonas aeruginosa
,
Stenotrophomonas maltophilia
, and
Aspergillus fumigatus
were sporadically observed.
Mycobacterium avium
complex and
Acanthamoeba
spp. were not detected. Season had no influence on the occurrence of these organisms, except for NTM and
S. maltophilia
, which were present in higher numbers in the summer. Opportunistic pathogens were more often observed in premise plumbing water samples than in samples from the distribution system. The lowest number of these organisms was observed in the finished water at the plant. Thus, fungi, NTM, and some of the studied opportunistic pathogens can multiply in the distribution and premise plumbing systems. Assimilable organic carbon (AOC) and/or total organic carbon (TOC) had no clear effects on fungal and NTM numbers or on
P. aeruginosa
- and
S. maltophilia
-positive samples. However,
L. pneumophila
was detected more often in water with AOC concentrations above 10 μg C liter
−1
than in water with AOC levels below 5 μg C liter
−1
. Finally, samples that contained
L. pneumophila
,
P. aeruginosa
, or
S. maltophilia
were more frequently positive for a second opportunistic pathogen, which shows that certain drinking water types and/or sampling locations promote the growth of multiple opportunistic pathogens.
Temperature- and Salinity-Decoupled Overproduction of Hydroxyectoine by Chromohalobacter salexigens
Authors: Rodríguez-Moya Javier , Argandoña Montserrat , Iglesias-Guerra Fernando , Nieto Joaquín J. , Vargas Carmen
Published: November 2012

Hydroxyectoine overproduction by the natural producer
Chromohalobacter salexigens
is presented in this study. Genetically engineered strains were constructed that at low salinity coexpressed, in a vector derived from a native plasmid, the ectoine (
ectABC
) and hydroxyectoine (
ectD
) genes under the control of the
ectA
promoter, in a temperature-independent manner. Hydroxyectoine production was further improved by increasing the copies of
ectD
and using a
C. salexigens
genetic background unable to synthesize ectoines.
Comparative Genomic Analysis and Benzene, Toluene, Ethylbenzene, and
o
-,
m
-, and
p
-Xylene (BTEX) Degradation Pathways of Pseudoxanthomonas spadix BD-a59
Authors: Choi Eun Jin , Jin Hyun Mi , Lee Seung Hyeon , Math Renukaradhya K. , Madsen Eugene L. , Jeon Che Ok
Published: November 2012

Pseudoxanthomonas spadix
BD-a59, isolated from gasoline-contaminated soil, has the ability to degrade all six BTEX (benzene, toluene, ethylbenzene, and
o
-,
m
-, and
p
-xylene) compounds. The genomic features of strain BD-a59 were analyzed bioinformatically and compared with those of another fully sequenced
Pseudoxanthomonas
strain,
P. suwonensis
11-1, which was isolated from cotton waste compost. The genome of strain BD-a59 differed from that of strain 11-1 in many characteristics, including the number of rRNA operons, dioxygenases, monooxygenases, genomic islands (GIs), and heavy metal resistance genes. A high abundance of phage integrases and GIs and the patterns in several other genetic measures (e.g., GC content, GC skew, Karlin signature, and clustered regularly interspaced short palindromic repeat [CRISPR] gene homology) indicated that strain BD-a59's genomic architecture may have been altered through horizontal gene transfers (HGT), phage attack, and genetic reshuffling during its evolutionary history. The genes for benzene/toluene, ethylbenzene, and xylene degradations were encoded on GI-9, -13, and -21, respectively, which suggests that they may have been acquired by HGT. We used bioinformatics to predict the biodegradation pathways of the six BTEX compounds, and these pathways were proved experimentally through the analysis of the intermediates of each BTEX compound using a gas chromatograph and mass spectrometry (GC-MS). The elevated abundances of dioxygenases, monooxygenases, and rRNA operons in strain BD-a59 (relative to strain 11-1), as well as other genomic characteristics, likely confer traits that enhance ecological fitness by enabling strain BD-a59 to degrade hydrocarbons in the soil environment.
Dynamics and Diversity of Escherichia coli in Animals and System Management of the Manure on a Commercial Farrow-to-Finish Pig Farm
Authors: Marchant Mauricio , Moreno Miguel A.
Published: November 2012

The objective of this study was to determine the dynamics and diversity of
Escherichia coli
populations in animal and environmental lines of a commercial farrow-to-finish pig farm in Spain along a full production cycle (July 2008 to July 2009), with special attention to antimicrobial resistance and the presence of integrons. In the animal line, a total of 256 isolates were collected from pregnant sows (10 samples and 20 isolates), 1-week-old piglets (20 samples and 40 isolates), unweaned piglets (20 samples and 38 isolates), growers (20 samples and 40 isolates), and the finishers' floor pen (6 samples and 118 isolates); from the underfloor pits and farm slurry tank environmental lines, 100 and 119 isolates, respectively, were collected. Our results showed that
E. coli
populations in the pig fecal microbiota and in the farm environment are highly dynamic and show high levels of diversity. These issues have been proven through DNA-based typing data (repetitive extragenic palindromic PCR [REP-PCR]) and phenotypic typing data (antimicrobial resistance profile comprising 19 antimicrobials). Clustering of the sampling groups based on their REP-PCR typing results showed that the spatial features (the line) had a stronger weight than the temporal features (sampling week) for the clustering of
E. coli
populations; this weight was less significant when clustering was performed based on resistotypes. Among animals, finishers harbored an
E. coli
population different from those of the remaining animal populations studied, considering REP-PCR fingerprints and resistotypes. This population, the most important from a public health perspective, demonstrated the lowest levels of antimicrobial resistance and integron presence.
Systems Engineering of Tyrosine 195, Tyrosine 260, and Glutamine 265 in Cyclodextrin Glycosyltransferase from Paenibacillus macerans To Enhance Maltodextrin Specificity for 2-
O
-
d
-Glucopyranosyl-
l
-Ascorbic Acid Synthesis
Authors: Han Ruizhi , Liu Long , Shin Hyun-dong , Chen Rachel R. , Li Jianghua , Du Guocheng , Chen Jian
Published: November 2012

In this work, the site saturation mutagenesis of tyrosine 195, tyrosine 260 and glutamine 265 in the cyclodextrin glycosyltransferase (CGTase) from
Paenibacillus macerans
was conducted to improve the specificity of CGTase for maltodextrin, which can be used as a cheap and easily soluble glycosyl donor for the synthesis of 2-
O
-
d
-glucopyranosyl-
l
-ascorbic acid (AA-2G). Specifically, the site-saturation mutagenesis of three sites—tyrosine 195, tyrosine 260, and glutamine 265—was performed, and it was found that the resulting mutants (containing the mutations Y195S [tyrosine → serine], Y260R [tyrosine → arginine], and Q265K [glutamine → lysine]) produced higher AA-2G yields than the wild type and the other mutant CGTases when maltodextrin was used as the glycosyl donor. Furthermore, double and triple mutations were introduced, and four mutants (containing Y195S/Y260R, Y195S/Q265K, Y260R/Q265K, and Y260R/Q265K/Y195S) were obtained and evaluated for the capacity to produce AA-2G. The Y260R/Q265K/Y195S triple mutant produced the highest titer of AA-2G at 1.92 g/liter, which was 60% higher than that (1.20 g/liter) produced by the wild-type CGTase. The kinetics analysis of AA-2G synthesis by the mutant CGTases confirmed the enhanced maltodextrin specificity, and it was also found that compared with the wild-type CGTase, all seven mutants had lower cyclization activities and higher hydrolysis and disproportionation activities. Finally, the mechanism responsible for the enhanced substrate specificity was explored by structure modeling, which indicated that the enhancement of maltodextrin specificity may be related to the changes of hydrogen bonding interactions between the side chain of residue at the three positions (195, 260, and 265) and the substrate sugars. This work adds to our understanding of the synthesis of AA-2G and makes the Y260R/Q265K/Y195S mutant a good starting point for further development by protein engineering.
Characterization and Molecular Epidemiology of a Fungal Infection of Edible Crabs (Cancer pagurus) and Interaction of the Fungus with the Dinoflagellate Parasite Hematodinium
Authors: Smith Amanda L. , Hamilton Kristina M. , Hirschle Lucy , Wootton Emma C. , Vogan Claire L. , Pope Edward C. , Eastwood Daniel C. , Rowley Andrew F.
Published: November 2012

This study reports on an emerging fungal disease of the edible crab,
Cancer pagurus
. Juvenile (prerecruit) crabs were found to be subject to this disease condition during the months of May to September at two intertidal sites in South Wales, United Kingdom. Histopathology revealed that the fungi overwhelm the host response in the tissues, leading to progressive septicemia. The causative agent of this infection was isolated and grown in pure culture and was identified as a member of the
Ophiocordyceps
clade by sequencing of the small subunit of the fungal ribosomal DNA (rDNA). Of the crabs naturally infected with the fungus, 94% had a coinfection with the parasitic dinoflagellate
Hematodinium
species. To determine if there was any interaction between the two disease-causing agents, apparently fungus-free crabs, both with and without natural
Hematodinium
infections, were challenged with the fungal isolate. The presence of
Hematodinium
caused a significant reduction in fungal multiplication in the hemocoel of the crabs in comparison to that in
Hematodinium
-free individuals. Histopathology of coinfected crabs showed a systemic multiplication of
Hematodinium
within host tissues, leading to a rapid death, while
Hematodinium
-free crabs experimentally infected with the fungal isolate died due to fungal sepsis (septicemia) with the same characteristic pathology as seen in natural infections.
Distribution of Clostridium botulinum Type E Strains in Nunavik, Northern Quebec, Canada
Authors: Leclair Daniel , Farber Jeffrey M. , Doidge Bill , Blanchfield Burke , Suppa Sandy , Pagotto Franco , Austin John W.
Published: November 2012

The distribution and levels of
Clostridium botulinum
type E were determined from field sites used by Inuit hunters for butchering seals along the coast of Nunavik. The incidence rates of
C. botulinum
type E in shoreline soil along the coast were 0, 50, and 87.5% among samples tested for the Hudson Strait, Hudson Bay, and Ungava Bay regions, respectively. Spores were detected in seawater or coastal rock surfaces from 17.6% of butchering sites, almost all of which were located in southern Ungava Bay. Concentrations of
C. botulinum
type E along the Ungava Bay coast were significantly higher than on the coasts of Hudson Strait and Hudson Bay, with the highest concentrations (270 to 1,800/kg of sample) found near butchering sites located along the mouths of large rivers. The Koksoak River contained high levels of
C. botulinum
type E, with the highest median concentration (270/kg) found in sediments of the marine portion of the river.
C. botulinum
type E was found in the intestinal contents (4.4%) and skins (1.4%) of seals. A high genetic biodiversity of
C. botulinum
type E isolates was observed among the 21 butchering sites and their surroundings along the Nunavik coastline, with 83% of isolates (44/53) yielding distinct pulsed-field gel electrophoresis genotypes. Multiple sources of
C. botulinum
type E may be involved in the contamination of seal meat during butchering in this region, but the risk of contamination appears to be much higher from environmental sources along the shoreline of southern Ungava Bay and the sediments of the Koksoak River.