bluuebunny/crossref_metadata_2025 huggingface dataset:
Tuning the carrier density of LaAlO3/SrTiO3 interfaces by capping La1−xSrxMnO3
Authors: Shi Y. J. , Wang S. , Zhou Y. , Ding H. F. , Wu D.
Published: February 2013

We present a systematical study on the electronic transport properties of the insulating LaAlO3 (3 unit cells)/SrTiO3 interfaces capping with thin layers of La1−xSrxMnO3, whose formal polarization is continually tuned by Sr doping. When the Sr doping is lower than 2/3, the LaAlO3/SrTiO3 interfaces show metallic behaviors. The carrier mobility is almost independent on the Sr doping for metallic interface, indicating that the capping layer does not change the density of the oxygen vacancies and the interface intermixing. However, the sheet carrier densities monotonically decrease as increasing Sr doping, which is ascribed to the decrease of the La1−xSrxMnO3 formal polarization. These results strongly support the intrinsic mechanism of the polar catastrophe model and provide a new approach to tailor the interface states of complex oxide heterostructures.
Control of conducting filaments in TiO2 films by a thin interfacial conducting oxide layer at the cathode
Authors: Keun Kim Seong , Joon Choi Byung , Jean Yoon Kyung , Woo Yoo Yeon , Seong Hwang Cheol
Published: February 2013

The influences of the conducting oxide layer and phases of TiO2 on the electroforming behavior of TiO2 films on Ru were studied for unipolar resistive switching. The thin RuO2 layer makes the conducting filaments (CF) too strong due to a limited oxygen supply and accompanying high power consumption. When the oxygen supply was too high (TiO2 film on thick RuO2), CF formation was essentially disturbed and no switching occurs. The phase of TiO2 does not have any relevance to the resistance switching. Fluent and uniform switching was achieved by spatially confining the CF to a local area.
Whispering gallery modes in zinc-blende AlN microdisks containing non-polar GaN quantum dots
Authors: Bürger M. , Ruth M. , Declair S. , Förstner J. , Meier C. , As D. J.
Published: February 2013

Whispering gallery modes (WGMs) were observed in 60 nm thin cubic AlN microdisk resonators containing a single layer of non-polar cubic GaN quantum dots. Freestanding microdisks were patterned by means of electron beam lithography and a two step reactive ion etching process. Micro-photoluminescence spectroscopy investigations were performed for optical characterization. We analyzed the mode spacing for disk diameters ranging from 2-4 μm. Numerical investigations using three dimensional finite difference time domain calculations were in good agreement with the experimental data. Whispering gallery modes of the radial orders 1 and 2 were identified by means of simulated mode field distributions.
Effects of impurity doping on ionic conductivity and polarization phenomenon in TlBr
Authors: Du Mao-Hua
Published: February 2013

Ionic conductivity due to vacancy diffusion and the resulting polarization phenomenon are major challenges to the development of TlBr radiation detector. It had been proposed that impurity doping of TlBr can suppress the ionic conductivity because the impurities can getter vacancies to form neutral complexes. This paper shows that the isolated vacancies can maintain their equilibrium concentrations even at room temperature, rendering any gettering methods ineffective. The main effect of doping is to change the Fermi level and consequently the vacancy concentration. The minimal ionic conductivity is reached at the donor concentration of [D+] = 4 × 1016 cm−3.
Membrane protein thermodynamic stability may serve as the energy sink for sorting in the periplasm
Authors: Moon C. Preston , Zaccai Nathan R. , Fleming Patrick J. , Gessmann Dennis , Fleming Karen G.
Published: February 2013

Thermodynamic stabilities are pivotal for understanding structure–function relationships of proteins, and yet such determinations are rare for membrane proteins. Moreover, the few measurements that are available have been conducted under very different experimental conditions, which compromises a straightforward extraction of physical principles underlying stability differences. Here, we have overcome this obstacle and provided structure–stability comparisons for multiple membrane proteins. This was enabled by measurements of the free energies of folding and the
m
values for the transmembrane proteins PhoP/PhoQ-activated gene product (PagP) and outer membrane protein W (OmpW) from
Escherichia coli
. Our data were collected in the same lipid bilayer and buffer system we previously used to determine those parameters for
E. coli
outer membrane phospholipase A (OmpLA). Biophysically, our results suggest that the stabilities of these proteins are strongly correlated to the water-to-bilayer transfer free energy of the lipid-facing residues in their transmembrane regions. We further discovered that the sensitivities of these membrane proteins to chemical denaturation, as judged by their
m
values, was consistent with that previously observed for water-soluble proteins having comparable differences in solvent exposure between their folded and unfolded states. From a biological perspective, our findings suggest that the folding free energies for these membrane proteins may be the thermodynamic sink that establishes an energy gradient across the periplasm, thus driving their sorting by chaperones to the outer membranes in living bacteria. Binding free energies of these outer membrane proteins with periplasmic chaperones support this energy sink hypothesis.
Vx-770 potentiates CFTR function by promoting decoupling between the gating cycle and ATP hydrolysis cycle
Authors: Jih Kang-Yang , Hwang Tzyh-Chang
Published: February 2013

Vx-770 (Ivacaftor), a Food and Drug Administration (FDA)-approved drug for clinical application to patients with cystic fibrosis (CF), shifts the paradigm from conventional symptomatic treatments to therapeutics directly tackling the root of the disease: functional defects of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel caused by pathogenic mutations. The underlying mechanism for the action of Vx-770 remains elusive partly because this compound not only increases the activity of wild-type (WT) channels whose gating is primarily controlled by ATP binding/hydrolysis, but also improves the function of G551D-CFTR, a disease-associated mutation that abolishes CFTR’s responsiveness to ATP. Here we provide a unified theory to account for this dual effect of Vx-770. We found that Vx-770 enhances spontaneous, ATP-independent activity of WT-CFTR to a similar magnitude as its effects on G551D channels, a result essentially explaining Vx-770’s effect on G551D-CFTR. Furthermore, Vx-770 increases the open time of WT-CFTR in an [ATP]-dependent manner. This distinct kinetic effect is accountable with a newly proposed CFTR gating model depicting an [ATP]-dependent “reentry” mechanism that allows CFTR shuffling among different open states by undergoing multiple rounds of ATP hydrolysis. We further examined the effect of Vx-770 on R352C-CFTR, a unique mutant that allows direct observation of hydrolysis-triggered gating events. Our data corroborate that Vx-770 increases the open time of WT-CFTR by stabilizing a posthydrolytic open state and thereby fosters decoupling between the gating cycle and ATP hydrolysis cycle. The current study also suggests that this unique mechanism of drug action can be further exploited to develop strategies that enhance the function of CFTR.
Lifespan of neurons is uncoupled from organismal lifespan
Authors: Magrassi Lorenzo , Leto Ketty , Rossi Ferdinando
Published: February 2013

Neurons in mammals do not undergo replicative aging, and, in absence of pathologic conditions, their lifespan is limited only by the maximum lifespan of the organism. Whether neuronal lifespan is determined by the strain-specific lifetime or can be extended beyond this limit is unknown. Here, we transplanted embryonic mouse cerebellar precursors into the developing brain of the longer-living Wistar rats. The donor cells integrated into the rat cerebellum developing into mature neurons while retaining mouse-specific morphometric traits. In their new environment, the grafted mouse neurons did not die at or before the maximum lifespan of their strain of origin but survived as long as 36 mo, doubling the average lifespan of the donor mice. Thus, the lifespan of neurons is not limited by the maximum lifespan of the donor organism, but continues when transplanted in a longer-living host.
Both information and social cohesion determine collective decisions in animal groups
Authors: Miller Noam , Garnier Simon , Hartnett Andrew T. , Couzin Iain D.
Published: February 2013

During consensus decision making, individuals in groups balance personal information (based on their own past experiences) with social information (based on the behavior of other individuals), allowing the group to reach a single collective choice. Previous studies of consensus decision making processes have focused on the informational aspects of behavioral choice, assuming that individuals make choices based solely on their likelihood of being beneficial (e.g., rewarded). However, decisions by both humans and nonhuman animals systematically violate such expectations. Furthermore, the typical experimental paradigm of assessing binary decisions, those between two mutually exclusive options, confounds two aspects common to most group decisions: minimizing uncertainty (through the use of personal and social information) and maintaining group cohesion (for example, to reduce predation risk). Here we experimentally disassociate cohesion-based decisions from information-based decisions using a three-choice paradigm and demonstrate that both factors are crucial to understanding the collective decision making of schooling fish. In addition, we demonstrate how multiple informational dimensions (here color and stripe orientation) are integrated within groups to achieve consensus, even though no individual is explicitly aware of, or has a unique preference for, the consensus option. Balancing of personal information and social cues by individuals in key frontal positions in the group is shown to be essential for such group-level capabilities. Our results demonstrate the importance of integrating informational with other social considerations when explaining the collective capabilities of group-living animals.
Evidence for maize (
Zea mays
) in the Late Archaic (3000–1800 B.C.) in the Norte Chico region of Peru
Authors: Haas Jonathan , Creamer Winifred , Huamán Mesía Luis , Goldstein David , Reinhard Karl , Rodríguez Cindy Vergel
Published: February 2013

For more than 40 y, there has been an active discussion over the presence and economic importance of maize (
Zea mays
) during the Late Archaic period (3000–1800 B.C.) in ancient Peru. The evidence for Late Archaic maize has been limited, leading to the interpretation that it was present but used primarily for ceremonial purposes. Archaeological testing at a number of sites in the Norte Chico region of the north central coast provides a broad range of empirical data on the production, processing, and consumption of maize. New data drawn from coprolites, pollen records, and stone tool residues, combined with 126 radiocarbon dates, demonstrate that maize was widely grown, intensively processed, and constituted a primary component of the diet throughout the period from 3000 to 1800 B.C.
Quinone-dependent proton transfer pathways in the photosynthetic cytochrome
b
6
f
complex
Authors: Hasan S. Saif , Yamashita Eiki , Baniulis Danas , Cramer William A.
Published: February 2013

As much as two-thirds of the proton gradient used for transmembrane free energy storage in oxygenic photosynthesis is generated by the cytochrome
b
6
f
complex. The proton uptake pathway from the electrochemically negative (n) aqueous phase to the n-side quinone binding site of the complex, and a probable route for proton exit to the positive phase resulting from quinol oxidation, are defined in a 2.70-Å crystal structure and in structures with quinone analog inhibitors at 3.07 Å (tridecyl-stigmatellin) and 3.25-Å (2-nonyl-4-hydroxyquinoline N-oxide) resolution. The simplest n-side proton pathway extends from the aqueous phase via Asp20 and Arg207 (cytochrome
b
6
subunit) to quinone bound axially to heme

c
n

. On the positive side, the heme-proximal Glu78 (subunit IV), which accepts protons from plastosemiquinone, defines a route for H
+
transfer to the aqueous phase. These pathways provide a structure-based description of the quinone-mediated proton transfer responsible for generation of the transmembrane electrochemical potential gradient in oxygenic photosynthesis.
Toward high-energy-density, high-efficiency, and moderate-temperature chip-scale thermophotovoltaics
Authors: Chan Walker R. , Bermel Peter , Pilawa-Podgurski Robert C. N. , Marton Christopher H. , Jensen Klavs F. , Senkevich Jay J. , Joannopoulos John D. , Soljačić Marin , Celanovic Ivan
Published: February 2013

The challenging problem of ultra-high-energy-density, high-efficiency, and small-scale portable power generation is addressed here using a distinctive thermophotovoltaic energy conversion mechanism and chip-based system design, which we name the microthermophotovoltaic (μTPV) generator. The approach is predicted to be capable of up to 32% efficient heat-to-electricity conversion within a millimeter-scale form factor. Although considerable technological barriers need to be overcome to reach full performance, we have performed a robust experimental demonstration that validates the theoretical framework and the key system components. Even with a much-simplified μTPV system design with theoretical efficiency prediction of 2.7%, we experimentally demonstrate 2.5% efficiency. The μTPV experimental system that was built and tested comprises a silicon propane microcombustor, an integrated high-temperature photonic crystal selective thermal emitter, four 0.55-eV GaInAsSb thermophotovoltaic diodes, and an ultra-high-efficiency maximum power-point tracking power electronics converter. The system was demonstrated to operate up to 800 °C (silicon microcombustor temperature) with an input thermal power of 13.7 W, generating 344 mW of electric power over a 1-cm
2
area.
Choice and dissonance in a European cultural context: The case of Western and Eastern Europeans
Authors: Kokkoris Michail D. , Kühnen Ulrich
Published: February 2013

Prior research demonstrates that members of collectivistic cultures are less likely to reduce cognitive dissonance after making a choice, compared to members of individualistic cultures. This difference has been attributed to different conceptualizations of choice that derive from different self‐construals across cultures. In individualistic cultures, choice leads to stronger commitment to the chosen option compared to collectivistic cultures, because it implicates core aspects of the independent self, such as personal preferences. However, this cultural variation in postchoice dissonance has thus far been studied exclusively by comparing East Asians and North Americans. Building on the assumption that this difference is due to different construals of the self, we conducted an experiment with movie choices using the classic free‐choice paradigm to examine differences in dissonance reduction between Western and Eastern Europeans, two populations known to differ with respect to interdependence. The results show that Eastern Europeans are less likely than Western Europeans to reduce postchoice dissonance by spreading their alternatives. Our findings speak to the generalizability of the hypothesis that in cultures differing in independence or interdependence people also differ in the way they construe choice, as well as in the way the act of choosing affects their self‐concept.
A Lightweight Battery for Backpack Electrofishing
Authors: Hockersmith Eric E. , Brooks Gabriel , Dumdei Nathan D. , Achord Stephen
Published: February 2013

A lithium ion battery was modified to replace the conventional sealed lead acid battery used to operate a backpack electrofishing unit. Specifications and performance of the lithium ion battery were compared with those of a lead acid battery of similar capacity. The lithium ion battery was 76% lighter in weight than the lead acid battery, reducing the overall weight of a Smith-Root model 12 backpack electrofishing unit and battery by 55%. Including the cost of a charger and parts to make the battery compatible with an electroshocking unit, the lithium ion battery and charger cost was 26% less than that of the lead acid battery and charger. Bench tests indicated the lithium ion battery provided 91% and 98% of the operating time of the lead acid battery per charge when the settings were 300 V at 90 Hz and 500 V at 90 Hz, respectively. The fuel gauge (battery discharge indicator) on the lithium ion battery, which was absent in the lead acid battery, provided the ability for a user to assess the remaining charge level while in the field. The lithium ion battery provided similar performance with a significant reduction in weight and cost compared with a conventional lead acid battery for backpack electrofishing. The lighter weight of the backpack electrofishing unit using the lithium ion battery can reduce fatigue and the risk of fatigue-related injuries to field crews.

Received March 23, 2012; accepted January 7, 2013
Patients who come back: Clinical characteristics and service outcome for patients re‐referred to an IAPT service
Authors: Cairns Margaret
Published: February 2013

Aims: Patients who are referred more than once to a Primary Care Mental Health Improving Access to Psychological Therapies (IAPT) Service raise questions about those patients' clinical characteristics, the appropriateness of the interventions offered and their capacity to make use of them. IAPT treatments are based on National Institute for Health and Clinical Excellence (NICE) guidelines for the treatment of common mental health problems. NICE recommendations are based on evidence gained from clinical trials, in particular Randomised Controlled Trials (RCTs), which tend to exclude the sort of patient with complex and co‐morbid conditions who often present in practice. Method: Using data routinely collected from the IAPTus clinical database, re‐referral patterns and level of complexity of 50 patients who were referred on more than one occasion to a Primary Care Mental Health (Improving Access to Psychological Therapies) Team from 2009–2010, were analysed. Results: The evidence presented in this study indicates patients who re‐refer exhibit complex environmental, historical and psychological problems. Implications for practice: Although further research is required to compare the characteristics of this patient group with those who are referred only once, this study provides limited evidence that such patients may be more likely to engage and complete treatments that offer regular, structured and one‐to‐one interventions.
Pretreating Channel Catfish with Copper Sulfate Affects Susceptibility to Columnaris Disease
Authors: Farmer Bradley D , Beck Benjamin H , Mitchell Andrew J , Straus David L
Published: February 2013

Columnaris disease is one of the most important bacterial diseases affecting Channel Catfish Ictalurus punctatus commercially grown in the USA. This disease can greatly diminish the profitability of aquaculture operations by large-scale mortality events, particularly in the fingerling production phase. Three experiments were conducted to evaluate the susceptibility of Channel Catfish fingerlings to columnaris disease when they were preexposed to copper sulfate (CuSO4). In experiment 1, fish were exposed for 24 h to 0, 1, 2, or 4 mg/L CuSO4 and were challenged immediately with Flavobacterium columnare, the etiological agent of columnaris disease. The resulting survival data indicated that fish preexposed to CuSO4 and then challenged exhibited significantly lower survival than did fish not exposed and then challenged. Experiment 2 was designed as above, except after the 24-h static exposure to CuSO4, fish were subjected to an additional 24 h in flow-through water prior to the challenge with F. columnare. In contrast to experiment 1, fish preexposed to CuSO4 and allowed an additional 24 h in flow-through water had a significantly higher survival rate than fish not exposed and then challenged. Experiment 3 evaluated the longevity of resistance to columnaris disease afforded by preexposure to CuSO4; in this experiment the remaining fish from experiment 2 were challenged 9 d after exposure to CuSO4. The increased survival rate of fish preexposed to CuSO4 was still significantly different, indicating the incurred resistance to F. columnare lasts for at least a week after exposure to CuSO4.
Lamin B1 fluctuations have differential effects on cellular proliferation and senescence
Authors: Dreesen Oliver , Chojnowski Alexandre , Ong Peh Fern , Zhao Tian Yun , Common John E. , Lunny Declan , Lane E. Birgitte , Lee Shu Jin , Vardy Leah A. , Stewart Colin L. , Colman Alan
Published: February 2013

The nuclear lamina consists of A- and B-type lamins. Mutations in LMNA cause many human diseases, including progeria, a premature aging syndrome, whereas LMNB1 duplication causes adult-onset autosomal dominant leukodystrophy (ADLD). LMNB1 is reduced in cells from progeria patients, but the significance of this reduction is unclear. In this paper, we show that LMNB1 protein levels decline in senescent human dermal fibroblasts and keratinocytes, mediated by reduced transcription and inhibition of LMNB1 messenger ribonucleic acid (RNA) translation by miRNA-23a. This reduction is also observed in chronologically aged human skin tissue. To determine whether altered LMNB1 levels cause senescence, we either increased or reduced LMNB1. Both LMNB1 depletion and overexpression inhibited proliferation, but only LMNB1 overexpression induced senescence, which was prevented by telomerase expression or inactivation of p53. This phenotype was exacerbated by a simultaneous reduction of LMNA/C. Our results demonstrate that altering LMNB1 levels inhibits proliferation and are relevant to understanding the molecular pathology of ADLD.
The WD40 protein Morg1 facilitates Par6–aPKC binding to Crb3 for apical identity in epithelial cells
Authors: Hayase Junya , Kamakura Sachiko , Iwakiri Yuko , Yamaguchi Yoshihiro , Izaki Tomoko , Ito Takashi , Sumimoto Hideki
Published: February 2013

Formation of apico-basal polarity in epithelial cells is crucial for both morphogenesis (e.g., cyst formation) and function (e.g., tight junction development). Atypical protein kinase C (aPKC), complexed with Par6, is considered to translocate to the apical membrane and function in epithelial cell polarization. However, the mechanism for translocation of the Par6–aPKC complex has remained largely unknown. Here, we show that the WD40 protein Morg1 (mitogen-activated protein kinase organizer 1) directly binds to Par6 and thus facilitates apical targeting of Par6–aPKC in Madin-Darby canine kidney epithelial cells. Morg1 also interacts with the apical transmembrane protein Crumbs3 to promote Par6–aPKC binding to Crumbs3, which is reinforced with the apically localized small GTPase Cdc42. Depletion of Morg1 disrupted both tight junction development in monolayer culture and cyst formation in three-dimensional culture; apico-basal polarity was notably restored by forced targeting of aPKC to the apical surface. Thus, Par6–aPKC recruitment to the premature apical membrane appears to be required for definition of apical identity of epithelial cells.
TGFβ restores hematopoietic homeostasis after myelosuppressive chemotherapy
Authors: Brenet Fabienne , Kermani Pouneh , Spektor Roman , Rafii Shahin , Scandura Joseph M.
Published: February 2013

Myelosuppression is a life-threatening complication of antineoplastic therapy, but treatment is restricted to a few cytokines with unilineage hematopoietic activity. Although hematopoietic stem cells (HSCs) are predominantly quiescent during homeostasis, they are rapidly recruited into cell cycle by stresses, including myelosuppressive chemotherapy. Factors that induce HSCs to proliferate during stress have been characterized, but it is not known how HSC quiescence is then reestablished. In this study, we show that TGFβ signaling is transiently activated in hematopoietic stem and progenitor cells (HSPCs) during hematopoietic regeneration. Blockade of TGFβ signaling after chemotherapy accelerates hematopoietic reconstitution and delays the return of cycling HSCs to quiescence. In contrast, TGFβ blockade during homeostasis fails to induce cycling of HSPCs. We identified the cyclin-dependent kinase inhibitor Cdkn1c (p57) as a key downstream mediator of TGFβ during regeneration because the recovery of chimeric mice, incapable of expressing p57 in HSPCs, phenocopies blockade of TGFβ signaling after chemotherapy. This study demonstrates that context-dependent activation of TGFβ signaling is central to an unrecognized counterregulatory mechanism that promotes homeostasis once hematopoiesis has sufficiently recovered from myelosuppressive chemotherapy. These results open the door to new, potentially superior, approaches to promote multilineage hematopoietic recovery by blocking the TGFβ signaling that dampens regeneration.
The Impact of Credit Constraints on Farm Households: Survey Results from India and China
Authors: Kumar Chandra S. , Turvey Calum G. , Kropp Jaclyn D.
Published: February 2013

India and China have the largest farm‐household populations in the world—populations that are also among the poorest. Among the many factors that affect farm livelihoods, access to credit has been identified as a significant barrier preventing the escape from poverty. While there has been significant research on credit constraints in developing countries, there is surprisingly little information pertaining to the actual impacts of credit constraints on household well‐being. The objective of this paper is to investigate the impacts of credit constraints on various factors affecting farm households, such as physical and human capital formation, agricultural inputs applications, consumption smoothing, and wage‐seeking behavior using direct elicitation. This paper contributes to the literature and policy debates by comparing the effects of credit constraints in China and India as surveyed in 2008–2009. The analytical results and data demonstrate that binding credit constraints adversely affect a broad range of production and livelihood choices. We empirically show that credit constraints negatively affect food consumption, farm input applications, and health and educational attainments.
Modeling Loan Repayment Behavior in Developing Countries
Authors: Bhattacharjee Manojit , Rajeev Meenakshi
Published: February 2013

Effective control of non‐performing assets (NPAs) is critical for sustainable and healthy growth in the banking sector of any economy. In this paper we attempt to establish a possible connection between the problems of loan non‐repayment in the formal credit market and credit accessibility from informal sources in India. The latter appears to flourish in many developing countries despite various government‐initiated formal lending programs. Scholars often examine how poorer households become the victim of usurious interest rates charged by informal lenders and thereby lose their valuable securities. Our approach, however, suggests that the more unfavorable the terms of loan from an informal moneylender compared with a formal lending agency, the better are the chances of a borrower making a timely repayment, and thus obtaining the benefits of a formal loan on a recurring basis (which is not available in the case of default). The paper uses the National Sample Survey Organization database (59th round, All India Debt and Investment Survey) to empirically examine the impact of interest rate in the informal sector on formal sector repayment. In addition to revealing a positive and significant impact of the informal sector's interest rate on the repayment of formal loans, the empirical analysis reveals a plausible negative impact of expectation regarding a loan waiver, as well as the moral hazard problem faced by formal lending agencies.
Environmental links to alosine at-sea distribution and bycatch in the Northwest Atlantic midwater trawl fishery
Authors: Bethoney N. David , Stokesbury Kevin D. E. , Cadrin Steven X.
Published: February 2013

The bycatch of river herring (Alosa pseudoharengus and A. aestivalis) and American shad (A. sapidissima) by midwater trawl vessels targeting Atlantic herring (Clupea harengus) and Atlantic mackerel (Scomber scombrus) has become a possible threat to their conservation. Most bycatch occurs during winter when the regional distributions of these five species overlap. The life histories and habits of these species suggest that there are times and areas during winter where overlap is low and bycatch could be reduced. This study identified environmental conditions associated with the presence of river herring and American shad during winter in the US Mid-Atlantic area by testing the hypothesis that fish were detected in an equal proportion to the amount of samples taken within an environmental condition. River herring were associated with colder temperatures and relatively shallow depths, while American shad appeared to be associated with a broader habitat. To determine whether these associations could be used to reduce bycatch, the proportion of effort and catch of target and bycatch species under the conditions associated with bycatch species presence was quantified in a fishery-dependent dataset. Targeting Atlantic mackerel in waters with surface temperatures above 6°C appeared to be the most effective advice for reducing river herring bycatch.
Rotational threshold in global numerical dynamo simulations
Authors: Schrinner M.
Published: February 2013

Magnetic field observations of low-mass stars reveal an increase of magnetic activity with increasing rotation rate. The so-called activity–rotation relation is usually attributed to changes in the underlying dynamo processes generating the magnetic field. We examine the dependence of the field strength on rotation in global numerical dynamo models and interpret our results on the basis of energy considerations. In agreement with the scaling law proposed by Christensen and Aubert, the field strength in our simulations is set by the fraction of the available power used for the magnetic field generation. This is controlled by the dynamo efficiency calculated as the ratio of ohmic to total dissipation in our models. The dynamo efficiency grows strongly with increasing rotation rate at a Rossby number of 0.1 until it reaches its upper bound of 1 and becomes independent of rotation. This gain in efficiency is related to the strong rotational dependence of the mean electromotive force in this parameter regime. For multipolar models at Rossby numbers clearly larger than 0.1, on the other hand, we do not find a systematic dependence of the field strength on rotation. Whether the enhancement of the dynamo efficiency found in our dipolar models explains the observed activity–rotation relation needs to be further assessed.
Functional Interplay Between Arabidopsis NADPH Oxidases and Heterotrimeric G Protein
Authors: Torres Miguel Angel , Morales Jorge , Sánchez-Rodríguez Clara , Molina Antonio , Dangl Jeffery L.
Published: February 2013

The plant NADPH oxidases produce reactive oxygen species (ROS) in response to pathogens that have diverse functions in different cellular contexts. Distinct phenotypic outcomes may derive from the interaction of NADPH oxidase-dependent ROS with other signaling components that mediate defense activation. We analyze the interaction between NADPH oxidases AtRbohD and AtRbohF and the Arabidopsis heterotrimeric G protein. The Gβ subunit (AGB1) of the heterotrimeric G protein is required for full disease resistance to different Pseudomonas syringae strains. Genetic studies reveal that, upon P. syringae infection, AGB1 and AtRbohD and AtRbohF can function in the same pathway, as the agb1 null allele is epistatic to the NADPH oxidase null alleles, combinatorial mutants display the agb1 phenotypes, and agb1 suppresses some of the atrbohD atrbohF double mutant phenotypes. In contrast, increased susceptibility to the necrotrophic fungus Plectosphaerella cucumerina displayed by agb1 and atrbohD atrbohF is enhanced in the agb1 atrbohD atrbohF triple mutant, suggesting that NADPH oxidase and heterotrimeric G proteins mediate different response pathways in response to this necrotrophic pathogen. The defense response mediated by AGB1 is independent of pathogen-dependent salicylic acid accumulation and signaling, as the agb1 sid2 (isochorismate synthase 2) double mutant showed enhanced disease susceptibility to P. syringae and Plectosphaerella cucumerina as compared with both single mutants. This study exemplifies the complex interplay between signaling events mediating defense activation, depending on the type of plant-pathogen interaction.
Looking beyond the DNA sequence: the relevance of DNA methylation processes for the stress–diathesis model of depression
Authors: Booij Linda , Wang Dongsha , Lévesque Mélissa L. , Tremblay Richard E. , Szyf Moshe
Published: February 2013

The functioning of the hypothalamic–pituitary–adrenal (HPA) axis and serotonergic (5-HT) system are known to be intertwined with mood. Alterations in these systems are often associated with depression. However, neither are sufficient to cause depression in and of themselves. It is now becoming increasingly clear that the environment plays a crucial role, particularly, the perinatal environment. In this review, we posit that early environmental stress triggers a series of epigenetic mechanisms that adapt the genome and programme the HPA axis and 5-HT system for survival in a harsh environment. We focus on DNA methylation as it is the most stable epigenetic mark. Given that DNA methylation patterns are in large part set within the perinatal period, long-term gene expression programming by DNA methylation is especially vulnerable to environmental insults during this period. We discuss specific examples of genes in the 5-HT system (serotonin transporter) and HPA axis (glucocorticoid receptor and arginine vasopressin enhancer) whose DNA methylation state is associated with early life experience and may potentially lead to depression vulnerability. We conclude with a discussion on the relevance of studying epigenetic mechanisms in peripheral tissue as a proxy for those occurring in the human brain and suggest avenues for future research.
Interplay between Heat Shock Proteins HSP101 and HSA32 Prolongs Heat Acclimation Memory Posttranscriptionally in Arabidopsis
Authors: Wu Ting-ying , Juan Yu-ting , Hsu Yang-hsin , Wu Sze-hsien , Liao Hsiu-ting , Fung Raymond W.M. , Charng Yee-yung
Published: February 2013

Heat acclimation improves the tolerance of organisms to severe heat stress. Our previous work showed that in Arabidopsis (Arabidopsis thaliana), the “memory” of heat acclimation treatment decayed faster in the absence of the heat-stress-associated 32-kD protein HSA32, a heat-induced protein predominantly found in plants. The HSA32 null mutant attains normal short-term acquired thermotolerance but is defective in long-term acquired thermotolerance. To further explore this phenomenon, we isolated Arabidopsis defective in long-term acquired thermotolerance (dlt) mutants using a forward genetic screen. Two recessive missense alleles, dlt1-1 and dlt1-2, encode the molecular chaperone heat shock protein101 (HSP101). Results of immunoblot analyses suggest that HSP101 enhances the translation of HSA32 during recovery after heat treatment, and in turn, HSA32 retards the decay of HSP101. The dlt1-1 mutation has little effect on HSP101 chaperone activity and thermotolerance function but compromises the regulation of HSA32. In contrast, dlt1-2 impairs the chaperone activity and thermotolerance function of HSP101 but not the regulation of HSA32. These results suggest that HSP101 has a dual function, which could be decoupled by the mutations. Pulse-chase analysis showed that HSP101 degraded faster in the absence of HSA32. The autophagic proteolysis inhibitor E-64d, but not the proteasome inhibitor MG132, inhibited the degradation of HSP101. Ectopic expression of HSA32 confirmed its effect on the decay of HSP101 at the posttranscriptional level and showed that HSA32 was not sufficient to confer long-term acquired thermotolerance when the HSP101 level was low. Taken together, we propose that a positive feedback loop between HSP101 and HSA32 at the protein level is a novel mechanism for prolonging the memory of heat acclimation.
Jasmonate Controls Leaf Growth by Repressing Cell Proliferation and the Onset of Endoreduplication while Maintaining a Potential Stand-By Mode
Authors: Noir Sandra , Bömer Moritz , Takahashi Naoki , Ishida Takashi , Tsui Tjir-Li , Balbi Virginia , Shanahan Hugh , Sugimoto Keiko , Devoto Alessandra
Published: February 2013

Phytohormones regulate plant growth from cell division to organ development. Jasmonates (JAs) are signaling molecules that have been implicated in stress-induced responses. However, they have also been shown to inhibit plant growth, but the mechanisms are not well understood. The effects of methyl jasmonate (MeJA) on leaf growth regulation were investigated in Arabidopsis (Arabidopsis thaliana) mutants altered in JA synthesis and perception, allene oxide synthase and coi1-16B (for coronatine insensitive1), respectively. We show that MeJA inhibits leaf growth through the JA receptor COI1 by reducing both cell number and size. Further investigations using flow cytometry analyses allowed us to evaluate ploidy levels and to monitor cell cycle progression in leaves and cotyledons of Arabidopsis and/or Nicotiana benthamiana at different stages of development. Additionally, a novel global transcription profiling analysis involving continuous treatment with MeJA was carried out to identify the molecular players whose expression is regulated during leaf development by this hormone and COI1. The results of these studies revealed that MeJA delays the switch from the mitotic cell cycle to the endoreduplication cycle, which accompanies cell expansion, in a COI1-dependent manner and inhibits the mitotic cycle itself, arresting cells in G1 phase prior to the S-phase transition. Significantly, we show that MeJA activates critical regulators of endoreduplication and affects the expression of key determinants of DNA replication. Our discoveries also suggest that MeJA may contribute to the maintenance of a cellular “stand-by mode” by keeping the expression of ribosomal genes at an elevated level. Finally, we propose a novel model for MeJA-regulated COI1-dependent leaf growth inhibition.
Vascular performance of woody plants in a temperate rain forest: lianas suffer higher levels of freeze–thaw embolism than associated trees
Authors: Jiménez‐Castillo Mylthon , Lusk Christopher H.
Published: February 2013

The success of lianas in tropical rain forests has been linked to their wide xylem vessels that confer much higher hydraulic conductivity than tropical trees. In contrast, the poorer representation of lianas in temperate forests and high elevations might reflect lower competitiveness there, because of the vulnerability of high‐performance xylem to freeze–thaw embolism. Nevertheless, the empirical evidence that support this idea is surprisingly scarce.

We assessed this hypothesis comparing the hydraulic performance of five lianas and nine trees coexisting in cold weather, by measuring wood traits, hydraulic conductivity, xylem embolism and root pressures.

Vessel diameters of lianas were on average twice those of trees (51·3 vs. 23·2 μm), resulting in an 18‐fold difference in mean specific hydraulic conductivity (15·5 vs. 1·05 kg s−1 m−1 MPa−1). Lianas on average suffered higher levels of freeze–thaw embolism than trees (29·9 vs. 12·8%), reducing their potential hydraulically supported competitive advantage; however, partially embolized lianas still had greater water transport capacity than trees.

Specific hydraulic conductivity (Ks) was well correlated with vessel size in lianas but not in trees; however, plants with big vessels were more vulnerable to freeze embolism. Although all species of lianas developed root pressures and these tended to be higher than trees, root pressure were insufficient to repair embolism in plants > c. 7 m tall. The magnitudes of root pressure were well correlated with vessel size in lianas, but this relationship was not observed in trees.

Synthesis: Our results show empirical evidence that hydraulic performance of temperate lianas exceed the performance of coexisting trees, in similar magnitude than its tropical counterparts. Nevertheless, this hydraulic advantage is reduced as a consequence of freeze embolism. Temperate lianas appear to employ a bet‐hedging strategy entailing significant embolism in winter, but likely enabling rapid carbon gain during frost‐free periods. Loss of winter carbon gain opportunities because of embolism may explain the low success of lianas in temperate rain forest. However, predicted future climatic scenarios could are likely to increase liana abundance in mid‐latitudes and allow lianas to expand their ranges towards higher latitudes and elevations.
Minimizing invasive potential ofMiscanthus × giganteusgrown for bioenergy: identifying demographic thresholds for population growth and spread
Authors: Matlaga David P. , Davis Adam S.
Published: February 2013

Spatial demographic models offer a powerful tool for quantifying risk of invasive spread by bioenergy crops. Our results suggest that sterile and fertile cultivars ofM. × giganteushave markedly different invasive potential and therefore should be considered separately in management and policy decisions. Feral populations of sterileM. × giganteuswould need to experience frequent and severe disturbance to pose a significant invasion risk, indicating that they should be grown well away from riparian areas prone to streambank scouring. In contrast, cultivars ofM. × giganteusbearing fertile seed may be very difficult, if not impossible, to contain.
WormFarm: a quantitative control and measurement device toward automated Caenorhabditis elegans aging analysis
Authors: Xian Bo , Shen Jie , Chen Weiyang , Sun Na , Qiao Nan , Jiang Dongqing , Yu Tao , Men Yongfan , Han Zhijun , Pang Yuhong , Kaeberlein Matt , Huang Yanyi , Han Jing‐Dong J.
Published: February 2013

Caenorhabditis elegans is a leading model organism for studying the basic mechanisms of aging. Progress has been limited, however, by the lack of an automated system for quantitative analysis of longevity and mean lifespan. To address this barrier, we developed ‘WormFarm’, an integrated microfluidic device for culturing nematodes. Cohorts of 30–50 animals are maintained throughout their lifespan in each of eight separate chambers on a single WormFarm polydimethylsiloxane chip. Design features allow for automated removal of progeny and efficient control of environmental conditions. In addition, we have developed computational algorithms for automated analysis of video footage to quantitate survival and other phenotypes, such as body size and motility. As proof‐of‐principle, we show here that WormFarm successfully recapitulates survival data obtained from a standard plate‐based assay for both RNAi‐mediated and dietary‐induced changes in lifespan. Further, using a fluorescent reporter in conjunction with WormFarm, we report an age‐associated decrease in fluorescent intensity of GFP in transgenic worms expressing GFP tagged with a mitochondrial import signal under the control of the myo‐3 promoter. This marker may therefore serve as a useful biomarker of biological age and aging rate.
Histological Variations of the Glenoid Labrum in Dogs
Authors: Sager M. , Herten M. , Dreiner L. , Engelhardt E. , Assheuer J. , Kramer M. , Jäger M.
Published: February 2013

As the structure and clinical meaning of the canine glenoid labrum are repeatedly disputed up to now, an anatomical histological description of the structure and its varieties in older dogs is carried out. In this study, 20 shoulder joints are histologically and immunohistologically examined. The glenoid labrum (GL) is composed of up to three different zones: a transition zone composed of fibre cartilage with collagen fibres arranged like a fishnet‐like pattern, a zone of circularly leading fibre bundles and a meniscoid fold with synovial coverage. A variable recess exists between the GL and the joint surface.
PTPN22 Gene Polymorphism (C1858T) Is Associated with Susceptibility to Type 1 Diabetes: A Meta‐Analysis of 19,495 Cases and 25,341 Controls
Authors: Xuan Chao , Lun Li‐Min , Zhao Jin‐Xia , Wang Hong‐Wei , Zhu Bao‐Zhi , Yu Shui , Liu Zhen , He Guo‐Wei
Published: February 2013

The protein tyrosine phosphatase N22 (PTPN22) gene C1858T polymorphism has been reported to be associated with susceptibility to type 1 diabetes (T1D) in relatively small sample sizes. This study aimed at investigating the pooled association by carrying out a meta‐analysis on the published studies. The Medline, EBSCO, and BIOSIS databases were searched to identify eligible studies published in English before June 2012. The association was assessed by odds ratio (OR) with 95% confidence intervals (CI). The presence of heterogeneity and publication bias was explored by using meta‐regression analysis and Begg's test, respectively. A total of 28 studies were involved in this meta‐analysis. Across all populations, significant associations were found between the PTPN22 C1858T polymorphism and susceptibility to T1D under genotypic (TT vs. CC [OR = 3.656, 95% CI: 3.139–4.257], CT vs. CC [OR = 1.968, 95% CI: 1.683–2.300]), recessive (OR = 3.147, 95% CI: 2.704–3.663), and dominant models (OR = 1.957, 95% CI: 1.817–2.108). In ethnicity‐ and sex‐stratified analyses, similar associations were found among Caucasians and within Caucasian male and female strata. The meta‐analysis results suggest that the PTPN22 C1858T polymorphism was associated with susceptibility to T1D among the Caucasian population, and males who carried the ‐1858T allele were more susceptible to T1D than females.
Why Do Partisan Media Polarize Viewers?
Authors: Levendusky Matthew S.
Published: February 2013

The recent increase in partisan media has generated interest in whether such outlets polarize viewers. I draw on theories of motivated reasoning to explain why partisan media polarize viewers, why these programs affect some viewers much more strongly than others, and how long these effects endure. Using a series of original experiments, I find strong support for my theoretical expectations, including the argument that these effects can still be detected several days postexposure. My results demonstrate that partisan media polarize the electorate by taking relatively extreme citizens and making them even more extreme. Though only a narrow segment of the public watches partisan media programs, partisan media's effects extend much more broadly throughout the political arena.
Genetic diversity and structure in Asian native goat analyzed by newly developed SNP markers
Authors: Lin Bang Zhong , Kato Taiki , Kaneda Makoto , Matsumoto Hirokazu , Sasazaki Shinji , Mannen Hideyuki
Published: February 2013

In the current study, a total of 65 single nucleotide polymorphisms (SNPs) within the intron region were developed in goat (Capra hircus) by utilizing genomic information of cattle and sheep due to poor available genomic information on goat. Using these markers, we carried out genetic diversity and structure analyses for 10 Asian goat populations. The phylogenetic tree and principal components analysis showed good correspondence between clustered populations and their geographic locations. The STRUCTURE software analysis illustrated six divergent genetic structures among 10 populations. Myanmar and Cambodia populations showed high admixture patterns with different ancestry, suggesting genetic introgression into native goat populations. We also investigated the correlation between genetic diversity and geographic distance from a domestication center. This result showed a decreasing trend of genetic diversity according to the distance (P = 0.014). This result supported common consensus that western Asia is one of the centers of origin for modern Asian domestic goat.