bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural insight into how the human helicase subunit MCM2 may act as a histone chaperone together with ASF1 at the replication fork
Authors: Richet Nicolas , Liu Danni , Legrand Pierre , Velours Christophe , Corpet Armelle , Gaubert Albane , Bakail May , Moal-Raisin Gwenaelle , Guerois Raphael , Compper Christel , Besle Arthur , Guichard Berengère , Almouzni Genevieve , Ochsenbein Françoise
Published: January 2015

MCM2 is a subunit of the replicative helicase machinery shown to interact with histones H3 and H4 during the replication process through its N-terminal domain. During replication, this interaction has been proposed to assist disassembly and assembly of nucleosomes on DNA. However, how this interaction participates in crosstalk with histone chaperones at the replication fork remains to be elucidated. Here, we solved the crystal structure of the ternary complex between the histone-binding domain of Mcm2 and the histones H3-H4 at 2.9 Å resolution. Histones H3 and H4 assemble as a tetramer in the crystal structure, but MCM2 interacts only with a single molecule of H3-H4. The latter interaction exploits binding surfaces that contact either DNA or H2B when H3-H4 dimers are incorporated in the nucleosome core particle. Upon binding of the ternary complex with the histone chaperone ASF1, the histone tetramer dissociates and both MCM2 and ASF1 interact simultaneously with the histones forming a 1:1:1:1 heteromeric complex. Thermodynamic analysis of the quaternary complex together with structural modeling support that ASF1 and MCM2 could form a chaperoning module for histones H3 and H4 protecting them from promiscuous interactions. This suggests an additional function for MCM2 outside its helicase function as a proper histone chaperone connected to the replication pathway.
Functional regulation of the DNA damage-recognition factor DDB2 by ubiquitination and interaction with xeroderma pigmentosum group C protein
Authors: Matsumoto Syota , Fischer Eric S. , Yasuda Takeshi , Dohmae Naoshi , Iwai Shigenori , Mori Toshio , Nishi Ryotaro , Yoshino Ken-ichi , Sakai Wataru , Hanaoka Fumio , Thomä Nicolas H. , Sugasawa Kaoru
Published: January 2015

In mammalian nucleotide excision repair, the DDB1–DDB2 complex recognizes UV-induced DNA photolesions and facilitates recruitment of the XPC complex. Upon binding to damaged DNA, the Cullin 4 ubiquitin ligase associated with DDB1–DDB2 is activated and ubiquitinates DDB2 and XPC. The structurally disordered N-terminal tail of DDB2 contains seven lysines identified as major sites for ubiquitination that target the protein for proteasomal degradation; however, the precise biological functions of these modifications remained unknown. By exogenous expression of mutant DDB2 proteins in normal human fibroblasts, here we show that the N-terminal tail of DDB2 is involved in regulation of cellular responses to UV. By striking contrast with behaviors of exogenous DDB2, the endogenous DDB2 protein was stabilized even after UV irradiation as a function of the XPC expression level. Furthermore, XPC competitively suppressed ubiquitination of DDB2 in vitro, and this effect was significantly promoted by centrin-2, which augments the DNA damage-recognition activity of XPC. Based on these findings, we propose that in cells exposed to UV, DDB2 is protected by XPC from ubiquitination and degradation in a stochastic manner; thus XPC allows DDB2 to initiate multiple rounds of repair events, thereby contributing to the persistence of cellular DNA repair capacity.
NTF2-like domain of Tap plays a critical role in cargo mRNA recognition and export
Authors: Katahira Jun , Dimitrova Lyudmila , Imai Yumiko , Hurt Ed
Published: January 2015

Metazoan Tap-p15 (also called Nxf1-Nxt1) and yeast Mex67-Mtr2 heterodimers are the general mRNA export receptors. The RNA binding activity of Tap-p15, which is essential for mRNA nuclear export, has been attributed to the amino-terminal RNA binding module of Tap consists of RNA recognition motif (RRM) and leucine-rich repeat. In this study, we identified a novel RNA interaction surface in the NTF2-like (NTF2L) domain of Tap, which is analogous to the rRNA binding platform of Mex67-Mtr2. Tap-p15 uses the three domains to tightly bind the retroviral constitutive transport element. The RNA binding through the NTF2L domain is functionally relevant as introduction of mutations in this region reduced CTE-containing mRNA export activity. In contrast, only when the RRM and NTF2L domains were mutated simultaneously, bulk poly (A)+ RNA export and in vivo poly (A)+ RNA binding activities of Tap-p15 were significantly attenuated. Moreover, an engineered human cell line harboring the NTF2L domain mutation in the NXF1 gene showed a synthetic growth phenotype and severe mRNA export defect under Aly/REF and Thoc5 depleted condition. These data suggest that Tap-p15 recognizes bulk mRNAs through combinatorial use of the distinct RNA binding domains.
Engineered ribosomal RNA operon copy-number variants of E. coli reveal the evolutionary trade-offs shaping rRNA operon number
Authors: Gyorfy Zsuzsanna , Draskovits Gabor , Vernyik Viktor , Blattner Frederick F. , Gaal Tamas , Posfai Gyorgy
Published: January 2015

Ribosomal RNA (rrn) operons, characteristically present in several copies in bacterial genomes (7 in E. coli), play a central role in cellular physiology. We investigated the factors determining the optimal number of rrn operons in E. coli by constructing isogenic variants with 5–10 operons. We found that the total RNA and protein content, as well as the size of the cells reflected the number of rrn operons. While growth parameters showed only minor differences, competition experiments revealed a clear pattern: 7–8 copies were optimal under conditions of fluctuating, occasionally rich nutrient influx and lower numbers were favored in stable, nutrient-limited environments. We found that the advantages of quick adjustment to nutrient availability, rapid growth and economic regulation of ribosome number all contribute to the selection of the optimal rrn operon number. Our results suggest that the wt rrn operon number of E. coli reflects the natural, ‘feast and famine’ life-style of the bacterium, however, different copy numbers might be beneficial under different environmental conditions. Understanding the impact of the copy number of rrn operons on the fitness of the cell is an important step towards the creation of functional and robust genomes, the ultimate goal of synthetic biology.
Accurate transcriptome-wide prediction of microRNA targets and small interfering RNA off-targets with MIRZA-G
Authors: Gumienny Rafal , Zavolan Mihaela
Published: January 2015

Small interfering RNA (siRNA)-mediated knock-down is a widely used experimental approach to characterizing gene function. Although siRNAs are designed to guide the cleavage of perfectly complementary mRNA targets, acting similarly to microRNAs (miRNAs), siRNAs down-regulate the expression of hundreds of genes to which they have only partial complementarity. Prediction of these siRNA ‘off-targets’ remains difficult, due to the incomplete understanding of siRNA/miRNA–target interactions. Combining a biophysical model of miRNA–target interaction with structure and sequence features of putative target sites we developed a suite of algorithms, MIRZA-G, for the prediction of miRNA targets and siRNA off-targets on a genome-wide scale. The MIRZA-G variant that uses evolutionary conservation performs better than currently available methods in predicting canonical miRNA target sites and in addition, it predicts non-canonical miRNA target sites with similarly high accuracy. Furthermore, MIRZA-G variants predict siRNA off-target sites with an accuracy unmatched by currently available programs. Thus, MIRZA-G may prove instrumental in the analysis of data resulting from large-scale siRNA screens.
A Japanese Stretching Intervention Can Modify Lumbar Lordosis Curvature
Authors: Kadono Norio , Tsuchiya Kazushi , Uematsu Azusa , Kamoshita Hiroshi , Kiryu Kazunori , Hortobágyi Tibor , Suzuki Shuji
Published: January 2015

Study Design:

Eighteen healthy male adults were assigned to either an intervention or control group.

Objectives:

Isogai dynamic therapy (IDT) is one of Japanese stretching interventions and has been practiced for over 70 years. However, its scientific quantitative evidence remains unestablished. The objective of this study was to determine whether IDT could modify lumbar curvature in healthy young adults compared with stretching exercises used currently in clinical practice.

Summary of Background Data:

None of previous studies have provided data that conventional stretching interventions could modify spinal curvatures. However, this study provides the first evidence that a specific form of a Japanese stretching intervention can acutely modify the spinal curvatures.

Methods:

We compared the effects of IDT, a Japanese stretching intervention (n=9 males), with a conventional stretching routine (n=9 males) used widely in clinics to modify pelvic tilt and lumbar lordosis (LL) angle. We measured thoracic kyphosis (TK) and LL angles 3 times during erect standing using the Spinal Mouse before and after each intervention. IDT consisted of: (1) hip joint correction, (2) pelvic tilt correction, (3) lumbar alignment correction, and (4) squat exercise stretch. The control group performed hamstring stretches while (1) standing and (2) sitting.

Results:

IDT increased LL angle to 25.1 degrees (±5.9) from 21.2 degrees (±6.9) (P=0.047) without changing TK angle (pretest: 36.8 degrees [±6.9]; posttest: 36.1 degrees [±6.5]) (P=0.572). The control group showed no changes in TK (P=0.819) and LL angles (P=0.744).

Conclusions:

IDT can thus be effective for increasing LL angle, hence anterior pelvic tilt. Such modifications could ameliorate low back pain and improve mobility in old adults with an unfavorable pelvic position.
Beta Blockers Suppress Dextrose-Induced Endoplasmic Reticulum Stress, Oxidative Stress, and Apoptosis in Human Coronary Artery Endothelial Cells
Authors: Haas Michael J. , Kurban William , Shah Harshit , Onstead-Haas Luisa , Mooradian Arshag D.
Published: January 2015

Beta blockers are known to have favorable effects on endothelial function partly because of their capacity to reduce oxidative stress. To determine whether beta blockers can also prevent dextrose-induced endoplasmic reticulum (ER) stress in addition to their antioxidative effects, human coronary artery endothelial cells and hepatocyte-derived HepG2 cells were treated with 27.5 mM dextrose for 24 hours in the presence of carvedilol (a lipophilic beta blockers with alpha blocking activity), propranolol (a lipophilic nonselective beta blockers), and atenolol (a water-soluble selective beta blockers), and ER stress, oxidative, stress and cell death were measured. ER stress was measured using the placental alkaline phosphatase assay and Western blot analysis of glucose regulated protein 78, c-Jun-N-terminal kinase (JNK), phospho-JNK, eukaryotic initiating factor 2α (eIF2α), and phospho-eIF2α and measurement of X-box binding protein 1 (XBP1) mRNA splicing using reverse transcriptase-polymerase chain reaction. Superoxide (SO) generation was measured using the superoxide-reactive probe 2-methyl-6-(4-methoxyphenyl)-3,7-dihydroimidazo[1,2-A]pyrazin-3-one hydrochloride (MCLA) chemiluminescence. Cell viability was measured by propidium iodide staining method. The ER stress, SO production, and cell death induced by 27.5 mM dextrose were inhibited by all 3 beta blockers tested. The antioxidative and ER stress reducing effects of beta blockers were also observed in HepG2 cells. The salutary effects of beta blockers on endothelial cells in reducing both ER stress and oxidative stress may contribute to the cardioprotective effects of these agents.
Trophic convergence drives morphological convergence in marine tetrapods
Authors: Kelley Neil P. , Motani Ryosuke
Published: January 2015

Marine tetrapod clades (e.g. seals, whales) independently adapted to marine life through the Mesozoic and Caenozoic, and provide iconic examples of convergent evolution. Apparent morphological convergence is often explained as the result of adaptation to similar ecological niches. However, quantitative tests of this hypothesis are uncommon. We use dietary data to classify the feeding ecology of extant marine tetrapods and identify patterns in skull and tooth morphology that discriminate trophic groups across clades. Mapping these patterns onto phylogeny reveals coordinated evolutionary shifts in diet and morphology in different marine tetrapod lineages. Similarities in morphology between species with similar diets—even across large phylogenetic distances—are consistent with previous hypotheses that shared functional constraints drive convergent evolution in marine tetrapods.
On the predictive ability of mechanistic models for the Haitian cholera epidemic
Authors: Mari Lorenzo , Bertuzzo Enrico , Finger Flavio , Casagrandi Renato , Gatto Marino , Rinaldo Andrea
Published: January 2015

Predictive models of epidemic cholera need to resolve at suitable aggregation levels spatial data pertaining to local communities, epidemiological records, hydrologic drivers, waterways, patterns of human mobility and proxies of exposure rates. We address the above issue in a formal model comparison framework and provide a quantitative assessment of the explanatory and predictive abilities of various model settings with different spatial aggregation levels and coupling mechanisms. Reference is made to records of the recent Haiti cholera epidemics. Our intensive computations and objective model comparisons show that spatially explicit models accounting for spatial connections have better explanatory power than spatially disconnected ones for short-to-intermediate calibration windows, while parsimonious, spatially disconnected models perform better with long training sets. On average, spatially connected models show better predictive ability than disconnected ones. We suggest limits and validity of the various approaches and discuss the pathway towards the development of case-specific predictive tools in the context of emergency management.
Micro- and nano-structural details of a spider's filter for substrate vibrations: relevance for low-frequency signal transmission
Authors: Erko Maxim , Younes-Metzler Osnat , Rack Alexander , Zaslansky Paul , Young Seth L. , Milliron Garrett , Chyasnavichyus Marius , Barth Friedrich G. , Fratzl Peter , Tsukruk Vladimir , Zlotnikov Igor , Politi Yael
Published: January 2015

The metatarsal lyriform organ of the Central American wandering spider
Cupiennius salei
is its most sensitive vibration detector. It is able to sense a wide range of vibration stimuli over four orders of magnitude in frequency between at least as low as 0.1 Hz and several kilohertz. Transmission of the vibrations to the slit organ is controlled by a cuticular pad in front of it. While the mechanism of high-frequency stimulus transfer (above
ca
40 Hz) is well understood and related to the viscoelastic properties of the pad's epicuticle, it is not yet clear how low-frequency stimuli (less than 40 Hz) are transmitted. Here, we study how the pad material affects the pad's mechanical properties and thus its role in the transfer of the stimulus, using a variety of experimental techniques, such as X-ray micro-computed tomography for three-dimensional imaging, X-ray scattering for structural analysis, and atomic force microscopy and scanning electron microscopy for surface imaging. The mechanical properties were investigated using scanning acoustic microscopy and nanoindentation. We show that large tarsal deflections cause large deformation in the distal highly hydrated part of the pad. Beyond this region, a sclerotized region serves as a supporting frame which resists the deformation and is displaced to push against the slits, with displacement values considerably scaled down to only a few micrometres. Unravelling the structural arrangement in such specialized structures may provide conceptual ideas for the design of new materials capable of controlling a technical sensor's specificity and selectivity, which is so typical of biological sensors.
Multi-stable dynamics of the non-adiabatic repressilator
Authors: Potapov Ilya , Zhurov Boris , Volkov Evgeny
Published: January 2015

The assumption of the fast binding of transcription factors (TFs) to promoters is a typical point in studies of synthetic genetic circuits functioning in bacteria. Although the assumption is effective for simplifying the models, it becomes questionable in the light ofin vivomeasurements of the times TF spends searching for its cognate DNA sites. We investigated the dynamics of the full idealized model of the paradigmatic genetic oscillator, the repressilator, using deterministic mathematical modelling and stochastic simulations. We found (using experimentally approved parameter values) that decreases in the TF binding rate changes the type of transition between steady state and oscillation. As a result, this gives rise to the hysteresis region in the parameter space, where both the steady state and the oscillation coexist. We further show that the hysteresis is persistent over a considerable range of the parameter values, but the presence of the oscillations is limited by the low rate of TF dimer degradation. Finally, the stochastic simulation of the model confirms the hysteresis with switching between the two attractors, resulting in highly skewed period distributions. Moreover, intrinsic noise stipulates trains of large-amplitude modulations around the stable steady state outside the hysteresis region, which makes the period distributions bimodal.
Collective response to perturbations in a data-driven fish school model
Authors: Calovi Daniel S. , Lopez Ugo , Schuhmacher Paul , Chaté Hugues , Sire Clément , Theraulaz Guy
Published: January 2015

Fish schools are able to display a rich variety of collective states and behavioural responses when they are confronted by threats. However, a school's response to perturbations may be different depending on the nature of its collective state. Here we use a previously developed data-driven fish school model to investigate how the school responds to perturbations depending on its different collective states, we measure its susceptibility to such perturbations, and exploit its relation with the intrinsic fluctuations in the school. In particular, we study how a single or a small number of perturbing individuals whose attraction and alignment parameters are different from those of the main population affect the long-term behaviour of a school. We find that the responsiveness of the school to the perturbations is maximum near the transition region between milling and schooling states where the school exhibits multistability and regularly shifts between these two states. It is also in this region that the susceptibility, and hence the fluctuations, of the polarization order parameter is maximal. We also find that a significant school's response to a perturbation only happens below a certain threshold of the noise to social interactions ratio.
The relative efficiency of modular and non-modular networks of different size
Authors: Tosh Colin R. , McNally Luke
Published: January 2015

Most biological networks are modular but previous work with small model networks has indicated that modularity does not necessarily lead to increased functional efficiency. Most biological networks are large, however, and here we examine the relative functional efficiency of modular and non-modular neural networks at a range of sizes. We conduct a detailed analysis of efficiency in networks of two size classes: ‘small’ and ‘large’, and a less detailed analysis across a range of network sizes. The former analysis reveals that while the modular network is less efficient than one of the two non-modular networks considered when networks are small, it is usually equally or more efficient than both non-modular networks when networks are large. The latter analysis shows that in networks of small to intermediate size, modular networks are much more efficient that non-modular networks of the same (low) connective density. If connective density must be kept low to reduce energy needs for example, this could promote modularity. We have shown how relative functionality/performance scales with network size, but the precise nature of evolutionary relationship between network size and prevalence of modularity will depend on the costs of connectivity.
Epistasis can accelerate adaptive diversification in haploid asexual populations
Authors: Griswold Cortland K.
Published: January 2015

A fundamental goal of the biological sciences is to determine processes that facilitate the evolution of diversity. These processes can be separated into ecological, physiological, developmental and genetic. An ecological process that facilitates diversification is frequency-dependent selection caused by competition. Models of frequency-dependent adaptive diversification have generally assumed a genetic basis of phenotype that is non-epistatic. Here, we present a model that indicates diversification is accelerated by an epistatic basis of phenotype in combination with a competition model that invokes frequency-dependent selection. Our model makes use of a genealogical model of epistasis and insights into the effects of balancing selection on the genealogical structure of a population to understand how epistasis can facilitate diversification. The finding that epistasis facilitates diversification may be informative with respect to empirical results that indicate an epistatic basis of phenotype in experimental bacterial populations that experienced adaptive diversification.
A ‘NanoSuit’ surface shield successfully protects organisms in high vacuum: observations on living organisms in an FE-SEM
Authors: Takaku Yasuharu , Suzuki Hiroshi , Ohta Isao , Tsutsui Takami , Matsumoto Haruko , Shimomura Masatsugu , Hariyama Takahiko
Published: January 2015

Although extremely useful for a wide range of investigations, the field emission scanning electron microscope (FE-SEM) has not allowed researchers to observe living organisms. However, we have recently reported that a simple surface modification consisting of a thin extra layer, termed ‘NanoSuit’, can keep organisms alive in the high vacuum (10
−5
to 10
−7
Pa) of the SEM. This paper further explores the protective properties of the NanoSuit surface-shield. We found that a NanoSuit formed with the optimum concentration of Tween 20 faithfully preserves the integrity of an organism's surface without interfering with SEM imaging. We also found that electrostatic charging was absent as long as the organisms were alive, even if they had not been coated with electrically conducting materials. This result suggests that living organisms possess their own electrical conductors and/or rely on certain properties of the surface to inhibit charging. The NanoSuit seems to prolong the charge-free condition and increase survival time under vacuum. These findings should encourage the development of more sophisticated observation methods for studying living organisms in an FE-SEM.
Induced Jasmonate Signaling Leads to Contrasting Effects on Root Damage and Herbivore Performance
Authors: Lu Jing , Robert Christelle Aurélie Maud , Riemann Michael , Cosme Marco , Mène-Saffrané Laurent , Massana Josep , Stout Michael Joseph , Lou Yonggen , Gershenzon Jonathan , Erb Matthias
Published: January 2015

Induced defenses play a key role in plant resistance against leaf feeders. However, very little is known about the signals that are involved in defending plants against root feeders and how they are influenced by abiotic factors. We investigated these aspects for the interaction between rice (Oryza sativa) and two root-feeding insects: the generalist cucumber beetle (Diabrotica balteata) and the more specialized rice water weevil (Lissorhoptrus oryzophilus). Rice plants responded to root attack by increasing the production of jasmonic acid (JA) and abscisic acid, whereas in contrast to in herbivore-attacked leaves, salicylic acid and ethylene levels remained unchanged. The JA response was decoupled from flooding and remained constant over different soil moisture levels. Exogenous application of methyl JA to the roots markedly decreased the performance of both root herbivores, whereas abscisic acid and the ethylene precursor 1-aminocyclopropane-1-carboxylic acid did not have any effect. JA-deficient antisense 13-lipoxygenase (asLOX) and mutant allene oxide cyclase hebiba plants lost more root biomass under attack from both root herbivores. Surprisingly, herbivore weight gain was decreased markedly in asLOX but not hebiba mutant plants, despite the higher root biomass removal. This effect was correlated with a herbivore-induced reduction of sucrose pools in asLOX roots. Taken together, our experiments show that jasmonates are induced signals that protect rice roots from herbivores under varying abiotic conditions and that boosting jasmonate responses can strongly enhance rice resistance against root pests. Furthermore, we show that a rice 13-lipoxygenase regulates root primary metabolites and specifically improves root herbivore growth.
Two Distinct Domains of the UVR8 Photoreceptor Interact with COP1 to Initiate UV-B Signaling in Arabidopsis
Authors: Yin Ruohe , Arongaus Adriana B. , Binkert Melanie , Ulm Roman
Published: January 2015

UV-B photon reception by the Arabidopsis thaliana homodimeric UV RESISTANCE LOCUS8 (UVR8) photoreceptor leads to its monomerization and a crucial interaction with CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1). Relay of the subsequent signal regulates UV-B-induced photomorphogenesis and stress acclimation. Here, we report that two separate domains of UVR8 interact with COP1: the β-propeller domain of UVR8 mediates UV-B-dependent interaction with the WD40 repeats-based predicted β-propeller domain of COP1, whereas COP1 activity is regulated by interaction through the UVR8 C-terminal C27 domain. We show not only that the C27 domain is required for UVR8 activity but also that chemically induced expression of the C27 domain is sufficient to mimic UV-B signaling. We further show, in contrast with COP1, that the WD40 repeat proteins REPRESSOR OF UV-B PHOTOMORPHOGENESIS1 (RUP1) and RUP2 interact only with the UVR8 C27 domain. This coincides with their facilitation of UVR8 reversion to the ground state by redimerization and their potential to interact with UVR8 in a UV-B-independent manner. Collectively, our results provide insight into a key mechanism of photoreceptor-mediated signaling and its negative feedback regulation.
Admitting scientific expert evidence in the UK: reliability challenges and the need for revised criteria – proposing an Abridged Daubert
Authors: Ireland Jane , Beaumont John
Published: January 2015

Purpose

– Expert evidence is a contentious area with a number of high profile cases highlighting unreliable “scientific” expert evidence, leading to appeals and acquittals. The purpose of this paper is to argue for improvement in the assessment of expert evidence reliability to avoid such difficulties.

Design/methodology/approach

– A review of the area focused on the history of developing legal criteria for admitting “scientific” evidence. It examined the benefits and difficulties of approaches, and proposes an amendment to criteria for increased transparency and evidenced decision making.

Findings

– The review indicated a range of difficulties with “expert” evidence admissibility, including inconsistency, an over-focus on narrow elements of evidence, difficulties in interpretation, and the potential to unfairly restrict evidence. An alternative to current approaches is proposed. This takes the form of a two-stage approach to consider whether or not to admit expert evidence. It comprises a preparation and an examination stage. The former seeks to critically review the evidence and define its nature. The latter applies two sets of criteria; a Daubert application for generally accepted physical sciences, and proposes an Abridged-Daubert for novel and social/behavioural sciences. Also proposed is increased involvement by experts in critically reviewing their own evidence and in providing statements of limitations.

Practical implications

– The paper concludes by outlining the importance of developing such an approach for the UK legal system. It focuses on the application of specific criterion which could assist both Courts and witnesses to evaluate the quality of evidence prior to submission by accounting for the nature of the opinion evidence provided.

Originality/value

– The paper outlines a practical approach to examining evidence which has benefit to practitioners and advocates when opinion evidence is outlined.
Dividend yields and stock returns in Hong Kong
Authors: Lemmon Michael L. , Nguyen Thanh
Published: January 2015

Purpose

– The positive relationship between dividend yield and risk-adjusted return, which is called the dividend yield effect, is well documented in the US market. Yet, the drivers of the yield effect are unclear. Some argue this evidence is consistent with the prediction that the investor-level tax burden is capitalized in stock prices, also known as the tax capitalization hypothesis. Still others contend that nontax omitted factors drive the yield effect. The purpose of this paper is to contribute to the debate by exploring if the yield effect occurs in Hong Kong market where no taxes exist on either dividend income or capital gain.

Design/methodology/approach

– The authors use two main approaches to detect the dividend yield effect. The first approach groups stocks into portfolios based on dividend yields and tests for the presence of a yield effect at the portfolio level. The second approach employs the Fama-MacBeth methodology at the firm level and tests if a yield effect is existent after controlling for firm characteristics known to explain stock returns.

Findings

– The paper documents a robust dividend yield effect in the Hong Kong market and suggests that nontax reasons help to explain the yield effect.

Originality/value

– Tax capitalization is a long-standing question in financial economics and the research evidence is mixed. The findings do not completely rule out the tax capitalization hypothesis. The main contribution is to illustrate the difficulty of conducting a powerful test of this hypothesis in practice and to urge caution in interpreting the dividend yield effect as evidence in support of this hypothesis.
Dividend policy in India: new survey evidence
Authors: Baker H. Kent , Kapoor Sujata
Published: January 2015

Purpose

– The purpose of this paper is to survey managers of dividend-paying firms listed on the National Stock Exchange (NSE) in India to learn their views about the factors influencing dividend policy, dividend issues, and explanations for paying cash dividends and repurchasing shares. The authors compare the results to other dividend surveys based on firms in Indonesia, Canada, and the USA.

Design/methodology/approach

– The authors use questionnaire to gather primary data from a sample of 500 firms listed on the NSE.

Findings

– The most important determinants of dividends involve earnings (the stability of earnings as well as the level of current and expected future earnings) and the pattern of past dividends. Comparing the overall rankings of the 21 factors by respondents from Indian firms to those of Indonesian, Canadian, and US firms reveals statistically significant correlations. Respondents also perceive that dividend policy affects firm value. Respondents also view maintaining an uninterrupted record of dividends as important. The most highly supported explanations for paying cash dividends concern signaling, the firm life cycle, and catering. Although none of the theories of repurchasing shares is dominant, respondents provide little support for the agency explanation.

Research limitations/implications

– Although the tests suggest that the sample does not suffer from non-response bias, the findings should be viewed as suggestive rather than definitive because of the relatively low response rate.

Originality/value

– The paper presents new evidence about dividend policy of Indian firms. To the knowledge, this is the most comprehensive survey of Indian firms to date that captures managerial perceptions on both cash dividends and share repurchases.
Corporate dividend policy revisited
Authors: Baker H. Kent , Weigand Rob
Published: January 2015

Purpose

– The purpose of this paper is to provide an overview and synthesis of some important literature on dividend policy, chronicle changing perspectives and trends, provide stylized facts, offer practical implications, and suggest avenues for future research.

Design/methodology/approach

– The authors provide a survey of literature surveys with a focus on insights for paying cash dividends.

Findings

– The analysis of literature surveys on dividend policy provides some stylized facts. For example, US evidence indicates that the importance of cash dividends as a part of investors’ total returns has declined over time. Share repurchases now play an increasingly important role in payout policy in countries permitting stock buybacks. The popular view is that dividend policy is important, as evidenced by the large amount of money involved and the attention that firms, security analysts, and investors give to dividends. Firms tend to follow a managed dividend policy rather than a residual dividend policy, which involves paying dividends from earnings left over after meeting investment needs while maintaining its target capital structure. Certain determinants of cash dividends are consistently important over time in shaping actual dividend policies including the stability of past dividends and current and anticipated earnings. No universal set of factors is appropriate for all firms because dividend policy is sensitive to numerous factors including firm characteristics, market characteristics, and substitute forms of dividends. Universal or one-size-fits-all theories or explanations for why companies pay dividends are too simplistic.

Practical implications

– The dividend puzzle remains an important topic in modern finance.

Originality/value

– This is the first a survey of literature surveys on cash dividends.
Demateriality
Authors: Fimbel Eric , Binninger Anne-Sophie , Karyotis Catherine
Published: January 2015

Purpose

– The purpose of this article is to analyze the symbolic and practical impacts of demateriality in two areas that are emblematic of the way the modern world operates. Firstly, finance via currency, and secondly, trade via the relationship between trading firms and their customers. The article also addresses the current role played by so-called “information” technologies, exploring the double embedding of society within trade and trade within finance.

Design/methodology/approach

– A multidisciplinary approach which mobilizes available knowledge in finance, technology, marketing and sociology.

Findings

– The overall social power of the state of demateriality is that it reinforces the double-embedding.

Originality/value

– A multidisciplinary approach which mobilizes available knowledge in finance, technology, marketing and sociology to comprehend the role of a state, beyond the process creating that state.
More than three’s a crowd . . . in the best interest of companies!
Authors: Bouaiss Karima , Maque Isabelle , Meric Jérôme
Published: January 2015

Purpose

– The purpose of this paper was to decipher the contradictions and the ambiguities of crowdfunding as a term and as a practice to reveal the deeper significance of its underlying Zeitgeist.

Design/methodology/approach

– Three steps were followed. In the first one, the authors underline the ambiguities of crowd as a concept in its traditional meaning as well as in the realities, it may depict when referring to connected people. Thereafter, the many practices of crowdfunding with the apparent univocity of this term were confronted.

Findings

– These analyses led the authors to consider crowdfunding as ideology: an incantatory use of crowd can conceal an effective profit-making process, as well as a new way to unblock a stalling social elevator.

Originality/value

– As per the authors’ knowledge, this paper is the first one to try to conceptualize the social roots of crowdfunding and to analyze its deeper significance, as complementary to an already developed “how-to-do-it” literature. It is worth confronting this piece of reflexivity with the emerging literature on the assessment of specific crowdfunding operations.
Alternative theory for signal contribution sections and depth of investigation characteristics in electrical prospecting
Authors: Gómez‐Treviño Enrique , Flores Carlos
Published: January 2015

We present an alternative to Roy's theorem for direct current regimes with the aim of validating the theoretical basis of signal contribution sections in electrical prospecting. Roy's theorem establishes that the electrical potential at a point can be expressed as an integral over all space of the electric field weighted by the gradient of inverse distance. The integrand is interpreted to represent elementary contributions to the potential that can be analyzed to compare different electrode arrays. Signal contribution sections and depth of investigation characteristics can be beautifully illustrated with important practical applications. However, the electric potential, being the solution of a boundary value problem, cannot be uniquely decomposed into elementary contributions. There is no guarantee for the integrand of a given integral to be meaningful in all situations. In the case of Roy's theorem, the concept has been severely criticized by respected scholars who challenged the scientific legitimacy of his approach. If we are going to keep the concept of elementary contributions alive, we need to go beyond Roy's theorem. In this paper, we develop an alternative theorem and show that it merges with the concept of sensitivity, which is unique and mathematically sound, and is also open to physical validation. This prevents any possible contradictions in the future and, equally important, eliminates the dichotomy between sensitivity and elementary contributions.
Non‐additive effects of intra‐ and interspecific competition between two larval salamanders
Authors: Anderson Thomas L. , Whiteman Howard H.
Published: January 2015

Assessment of the relative strengths of intra‐ and interspecific competition has increased in recent years and is critical to understanding the importance of competition. Yet, whether intra‐ and interspecific competition can have non‐additive effects has rarely been tested. The resulting fitness consequences of such non‐additive interactions are important to provide the context necessary to advance our understanding of competition theory.

We compared the strength of additive and non‐additive intra‐ and interspecific competition by manipulating densities of a pair of larval salamanders (Ambystoma talpoideum and A. maculatum) in experimental mesocosms within a response surface design.

Intraspecific density had the strongest effect on the strength of competition for both species, and few observed comparisons indicated interspecific competition was an important factor in predicting body size, growth or larval period length of either species.

Non‐additive effects of intra‐ and interspecific competition influenced some response variables, including size and mass at metamorphosis in A. maculatum, but at a reduced strength compared to intraspecific effects alone.

Intraspecific competition was thus the dominant biotic interaction, but non‐additive effects also impact the outcome of competition in these species, validating the importance of testing for and incorporating non‐additive density effects into competition models.
Infectious disease transmission and behavioural allometry in wild mammals
Authors: Han Barbara A. , Park Andrew W. , Jolles Anna E. , Altizer Sonia
Published: January 2015

Animals’ social and movement behaviours can impact the transmission dynamics of infectious diseases, especially for pathogens transmitted through close contact between hosts or through contact with infectious stages in the environment.

Estimating pathogen transmission rates andR0from natural systems can be challenging. Because host behavioural traits that underlie the transmission process vary predictably with body size, one of the best‐studied traits among animals, body size might therefore also predict variation in parasite transmission dynamics.

Here, we examine how two host behaviours, social group living and the intensity of habitat use, scale allometrically using comparative data from wild primate, carnivore and ungulate species. We use these empirical relationships to parameterize classical compartment models for infectious micro‐ and macroparasitic diseases, and examine how the risk of pathogen invasion changes as a function of host behaviour and body size. We then test model predictions using comparative data on parasite prevalence and richness from wild mammals.

We report a general pattern suggesting that smaller‐bodied mammal species utilizing home ranges more intensively experience greater risk for invasion by environmentally transmitted macroparasites. Conversely, larger‐bodied hosts exhibiting a high degree of social group living could be more readily invaded by directly transmitted microparasites. These trends were supported through comparison of micro‐ and macroparasite species richness across a large number of carnivore, primate and ungulate species, but empirical data on carnivore macroparasite prevalence showed mixed results.

Collectively, our study demonstrates that combining host behavioural traits with dynamical models of infectious disease scaled against host body size can generate testable predictions for variation in parasite risk across species; a similar approach might be useful in future work focused on predicting parasite distributions in local host communities.
Spatiotemporal hierarchical modelling of species richness and occupancy using camera trap data
Authors: Tobler Mathias W. , Zúñiga Hartley Alfonso , Carrillo‐Percastegui Samia E. , Powell George V. N.
Published: January 2015

Over the last two decades, a large number of camera trap surveys have been carried out around the world and camera traps have been proposed as an ideal tool for inventorying and monitoring medium to large‐sized terrestrial vertebrates. However, few studies have analysed camera trap data at the community level.

We developed a multi‐session multi‐species occupancy model that allows us to obtain estimates for species richness and occupancy combining data from multiple camera trap surveys (sessions). By estimating species presence at the session‐level and modelling detection probability and occupancy for each species and sessions as nested random effects, we could improve parameter estimates for each session, especially for species with sparse data. We developed two variants of our model: one was a binary latent states model while the other used a Royle–Nichols formulation for the relationship between detection probability and abundance.

We applied both models to data from eight camera trap surveys from south‐eastern Peru including six study sites, 263 camera stations and 17 423 camera days. Sites covered protected areas, a logging concession and Brazil nut concessions. We included habitat (terra firme vs. floodplain) as a covariate for occupancy and trail vs. off‐trail as a covariate for detection.

Among‐camera heterogeneity was a serious problem for our data and the Royle–Nichols variant of our model had a much better fit than the binary‐state variant. Both models resulted in similar species richness estimates showing that most of the sites contained intact large mammal communities. Detection probabilities and occupancy values were more variable across species than across sessions within species. Three species showed a habitat preference and four species showed preference or avoidance of trails.

Synthesis and applications. Our multi‐session multi‐species occupancy model provides improved estimates for species richness and occupancy for a large data set. Our model is ideally suited for integrating large numbers of camera trap data sets to investigate regional and/or temporal patterns in the distribution and composition of mammal communities in relation to natural or anthropogenic factors or to monitor mammal communities over time.
High‐elevation range limit of an annual herb is neither caused nor reinforced by declining pollinator service
Authors: Hargreaves Anna L. , Weiner Jennifer L. , Eckert Christopher G.
Published: January 2015

Pollination failure has been proposed to be an important determinant of plant species’ range limits if pollinator activity declines along an environmental gradient, directly limiting plant populations, or if plant populations decline along an environmental gradient and subsequently fail to attract sufficient visitation. Both mechanisms predict reduced pollinator visitation, increased pollen limitation and decreased seed production towards range limits, and the first additionally predicts declining pollinator abundance independent of any particular plant species. However, many self‐compatible species have some capacity for autonomous self‐fertilization, which may buffer reproductive success from declining pollinator visitation if inbreeding depression is mild. Thus pollinator‐mediated limits may also predict selection for reduced reliance on pollinators towards range limits.

We tested these predictions towards the high‐elevation limit of the self‐compatible, bumblebee (Bombus)‐pollinatedRhinanthus minor,along two elevation transects in the Rocky Mountains of Alberta, Canada.

Bombusabundance was highest at mid‐ (range‐centre) and high‐elevation (range limit) sites, so declining pollinator abundance is unlikely to impose high‐elevation limits for bumblebee‐pollinated species in this area.

Flowers per plant and per m2declined at upper range limits, potentially rendering edge populations less attractive. However, visitation rate did not decline towards the range limit at either transect. Stigmatic pollen receipt declined with increasing elevation, but seed set did not, nor did outcross pollen supplementation increase seed set at any site.

Investment in floral attractiveness (corolla area/ovary area) increased towards range limits, but capacity for high‐quality autonomous seed set and adult inbreeding coefficients inferred from genetic markers were uniformly high, suggesting frequent self‐fertilization and weak inbreeding depression throughout the range.

Synthesis. We found no evidence for pollination failure towards the upper range limit ofR. minor. Moreover, unlike some species with a capacity for autogamy, autonomous selfing makes a major contribution toR. minor's mating system and demography, and likely buffers reproductive success from stochasticity in pollination. Continued investment in floral attractiveness despite high autonomous selfing suggests some evolutionary benefit to pollinator‐mediated outcrossing, rather than ecological benefits via increasing seed quantity or quality. Given that >50% of angiosperms are self‐compatible, the reproductive assurance provided by selfing may reduce the importance of pollination in limiting plant distributions compared to other biotic interactions.