bluuebunny/crossref_metadata_2025 huggingface dataset:
Mri Assessment of Cerebral Blood Flow after Experimental Traumatic Brain Injury Combined with Hemorrhagic Shock in Mice
Authors: Foley Lesley M , O'Meara Alia M Iqbal , Wisniewski Stephen R , Hitchens T Kevin , Melick John A , Ho Chien , Jenkins Larry W , Kochanek Patrick M
Published: October 2012

Secondary insults such as hypotension or hemorrhagic shock (HS) can greatly worsen outcome after traumatic brain injury (TBI). We recently developed a mouse combined injury model of TBI and HS using a controlled cortical impact (CCI) model and showed that 90 minutes of HS can exacerbate neuronal death in hippocampus beneath the contusion. This combined injury model has three clinically relevant phases, a shock, pre hospital, and definitive care phases. Mice were randomly assigned to four groups, shams as well as a CCI only, an HS only, and a CCI + HS groups. The CCI and HS reduced cerebral blood flow (CBF) in multiple regions of interest (ROIs) in the hemisphere ipsilateral and contralateral to injury. Hemorrhagic shock to a level of ~30 mm Hg exacerbated the CCI-induced CBF reductions in multiple ROIs ipsilateral to injury (hemisphere and thalamus) and in the hemisphere contralateral to injury (hemisphere, thalamus, hippocampus, and cortex, all P < 0.05 versus CCI only, HS only or both). An important effect of HS duration was also seen after CCI with maximal CBF reduction seen at 90 minutes ( P < 0.0001 group-time effect in ipsilateral hippocampus). Given that neuronal death in hippocampus is exacerbated by 90 minutes of HS in this model, our data suggest an important role for exacerbation of posttraumatic ischemia in mediating the secondary injury in CCI plus HS. In conclusion, the serial, non invasive assessment of CBF using ASL-MRI (magnetic resonance imaging with arterial spin labeling) is feasible in mice even in the complex setting of combined CCI + HS. The impact of resuscitation therapies and various mutant mouse strains on CBF and other outcomes merits investigation in this model.
Is Myelin a Mitochondrion?
Authors: Harris Julia J , Attwell David
Published: October 2012

It has been hypothesized that myelin acts like a mitochondrion, generating ATP across the membranes of its sheath. By calculating the proton motive force across the myelin membrane based on known values for the pH and membrane potential of the oligodendrocyte, we find that insufficient energy could be harvested from proton flow across the myelin membrane to synthesize ATP. In fact, if the respiratory chain were present in the myelin membrane, then the ATP synthase would function in reverse, hydrolyzing rather than synthesizing ATP. This calculation places the hypothesis of an energy-producing role for myelin in considerable doubt.
Immunologic Privilege in the Central Nervous System and the Blood–Brain Barrier
Authors: Muldoon Leslie L , Alvarez Jorge I , Begley David J , Boado Ruben J , del Zoppo Gregory J , Doolittle Nancy D , Engelhardt Britta , Hallenbeck John M , Lonser Russell R , Ohlfest John R , Prat Alexandre , Scarpa Maurizio , Smeyne Richard J , Drewes Lester R , Neuwelt Edward A
Published: October 2012

The brain is in many ways an immunologically and pharmacologically privileged site. The blood–brain barrier (BBB) of the cerebrovascular endothelium and its participation in the complex structure of the neurovascular unit (NVU) restrict access of immune cells and immune mediators to the central nervous system (CNS). In pathologic conditions, very well-organized immunologic responses can develop within the CNS, raising important questions about the real nature and the intrinsic and extrinsic regulation of this immune privilege. We assess the interactions of immune cells and immune mediators with the BBB and NVU in neurologic disease, cerebrovascular disease, and intracerebral tumors. The goals of this review are to outline key scientific advances and the status of the science central to both the neuroinflammation and CNS barriers fields, and highlight the opportunities and priorities in advancing brain barriers research in the context of the larger immunology and neuroscience disciplines. This review article was developed from reports presented at the 2011 Annual Blood-Brain Barrier Consortium Meeting.
Structural and functional insights into the role of the N-terminal Mps1 TPR domain in the SAC (spindle assembly checkpoint)
Authors: Thebault Philippe , Chirgadze Dimitri Y. , Dou Zhen , Blundell Tom L. , Elowe Sabine , Bolanos-Garcia Victor M.
Published: October 2012

The SAC (spindle assembly checkpoint) is a surveillance system that ensures the timely and accurate transmission of the genetic material to offspring. The process implies kinetochore targeting of the mitotic kinases Bub1 (budding uninhibited by benzamidine 1), BubR1 (Bub1 related) and Mps1 (monopolar spindle 1), which is mediated by the N-terminus of each kinase. In the present study we report the 1.8 Å (1 Å=0.1 nm) crystal structure of the TPR (tetratricopeptide repeat) domain in the N-terminal region of human Mps1. The structure reveals an overall high similarity to the TPR motif of the mitotic checkpoint kinases Bub1 and BubR1, and a number of unique features that include the absence of the binding site for the kinetochore structural component KNL1 (kinetochore-null 1; blinkin), and determinants of dimerization. Moreover, we show that a stretch of amino acids at the very N-terminus of Mps1 is required for dimer formation, and that interfering with dimerization results in mislocalization and misregulation of kinase activity. The results of the present study provide an important insight into the molecular details of the mitotic functions of Mps1 including features that dictate substrate selectivity and kinetochore docking.
Design of Clathrate Compounds that Use Only Weak Intermolecular Attractions
Authors: Bishop Roger
Published: October 2012

Intermolecular attractive forces that are considerably weaker than hydrogen bonding and coordination complexation may be used in the design of new molecules that function as host molecules in the solid-state. Known literature examples of accidentally discovered hosts (clathrands), which do not involve strong interactions in their crystals, are identified and discussed. Their molecular symmetry and supramolecular interactions are analysed in order to identify structural features that facilitate and promote molecular inclusion. The solid-state properties of a family of designed compounds that embody these principles are then described. Prediction of their inclusion behaviour was 95 % successful and a wide variety of crystal packing arrangements were encountered. This is an inevitable consequence of competition between many different molecular interactions of comparable energy during the crystallisation process. The lowest energy combination of these host–host and host–guest associations generates the observed outcome. One consequence of this behaviour is that detailed prediction of a new clathrate crystal packing arrangement is extremely difficult. However, a second consequence is that crystal structure analysis provides a rich source of information about weak intermolecular forces and new supramolecular synthons that previously had remained hidden.
Facile Synthesis of Triarylmethanimine Promoted by a Lewis Acid - Base Pair: Theoretical and Experimental Studies
Authors: Liu Yan , Yang Qiwu , Hao Dongling , Zhang Wenqin
Published: October 2012

An efficient method for triarylmethanimine synthesis promoted by a Lewis acid–base pair (AlCl3–Et3N) was designed using mechanistic analysis with the aid of density functional theory. A series of triarylmethanimines were successfully prepared under mild conditions in good to excellent yields with a simple work-up procedure. The promoter, the Lewis acid–base pair (AlCl3–Et3N), is inexpensive, efficient, and shows good functional group tolerance. The experimental results show that the electronic effect played a significant role, i.e. the reactions proceeded smoothly when electron-sufficient arylamines and electron-deficient ketones were used as substrates.
Synthesis and Pharmacological Evaluation of 4-Iminothiazolidinones for Inhibition of PI3 Kinase
Authors: Pinson Jo-Anne , Schmidt-Kittler Oleg , Frazzetto Mark , Zheng Zhaohua , Jennings Ian G. , Kinzler Kenneth W. , Vogelstein Bert , Chalmers David K. , Thompson Philip E.
Published: October 2012

The thiazolidinedione, compound 1, has previously shown pan-inhibition of the phosphoinositide 3-kinase (PI3K) class I isoforms. We hypothesized the derivatization of the thiazolidinedione core of compound 1 could introduce isoform selectivity. We report the synthesis, characterization, and inhibitory activity of a novel series of 4-iminothiazolidin-2-ones for inhibition of the class I PI3K isoforms. Their synthesis was successfully achieved by multiple pathways described in this paper. Initial in vitro data of 28 analogues demonstrated poor inhibition of all class I PI3K isoforms. However, we identified an alternate target, the phosphodiesterases, and present preliminary screening results showing improved inhibitory activity.
N-2-Propenyl-(5-dimethylamino)-1-naphthalene Sulfonamide, a Novel Fluorescent Monomer for the Molecularly Imprinted Polymer-Based Detection of 2,4-Dinitrotoluene in the Gas Phase
Authors: Turner Nicholas W. , Holdsworth Clovia I. , McCluskey Adam , Bowyer Michael C.
Published: October 2012

Fluorescent molecularly imprinted polymers (MIP) specific for 2,4-dinitrotoluene (DNT) have been synthesised using a novel monomer N-2-propenyl-(5-dimethylamino)-1-naphthalene sulfonamide. Three formats of the polymer were produced: a traditional bulk monolith ground into particles, a flexible, but highly cross-linked plasticiser-modified free standing membrane, and a hybrid material consisting of particles embedded in a poly(acrylonitrile) phase inversed film. Within all materials, a clearly defined imprinting effect was observed upon exposure to DNT vapour at room temperature. In all cases, preferential rebinding of DNT to the molecularly imprinted materials (3–5 times) over their non-imprinted (NIP) equivalents was evident within <10 min of contact with the DNT vapour stream. Fluorographic images of the fluorescent polymers showed the DNT binding-induced quenching to be significantly higher in the MIP material than in the non-imprinted control polymer.
Two New One-Dimensional Homospin Dy(III) Compounds Showing Slow Magnetic Relaxation
Authors: Luo Feng , Song Yu-Mei , Huang Hai-Xiao , Tian Xiao-Zhao , Sun Gong-Ming , Zhu Yan , Feng Xue-Feng
Published: October 2012

In this work, we present two new one-dimensional Dy(iii) compounds, namely [Dy3(L1)9]n (1, HL1 = benzoic acid) and {[Dy4(L2)14][Fe(phen)3]}n (2, HL2 = 3-nitrobenzoic acid, phen = 1,10-phenanthroline). In 1, three distinct coordination polyhedra for Dy(iii) sites including a six-coordinated DyO6 octahedron, a seven-coordinated DyO7 pentagonal bipyramid, and eight-coordinated DyO8 dodecahedron, are observed. These Dy(iii) ions are in turn bridged by L1––carboxylate to give rise to the 1D helical chain structure. Within 2, there are two crystallography-independent Dy(iii) ions that take the mono-capped trigonal bipyramidal geometry. Through L2-carboxylate bridges the Dy(iii) ions are associated together, resulting in the 1D chain structure. Direct current magnetic susceptibilities reveal ferromagnetic interactions, whilst dynamic magnetic studies via alternating current measurements disclose slow magnetic relaxation of these structures.
Emphysema diagnosis using X-ray dark-field imaging at a laser-driven compact synchrotron light source
Authors: Schleede Simone , Meinel Felix G. , Bech Martin , Herzen Julia , Achterhold Klaus , Potdevin Guillaume , Malecki Andreas , Adam-Neumair Silvia , Thieme Sven F. , Bamberg Fabian , Nikolaou Konstantin , Bohla Alexander , Yildirim Ali Ö. , Loewen Roderick , Gifford Martin , Ruth Ronald , Eickelberg Oliver , Reiser Maximilian , Pfeiffer Franz
Published: October 2012

In early stages of various pulmonary diseases, such as emphysema and fibrosis, the change in X-ray attenuation is not detectable with absorption-based radiography. To monitor the morphological changes that the alveoli network undergoes in the progression of these diseases, we propose using the dark-field signal, which is related to small-angle scattering in the sample. Combined with the absorption-based image, the dark-field signal enables better discrimination between healthy and emphysematous lung tissue in a mouse model. All measurements have been performed at 36 keV using a monochromatic laser-driven miniature synchrotron X-ray source (Compact Light Source). In this paper we present grating-based dark-field images of emphysematous vs. healthy lung tissue, where the strong dependence of the dark-field signal on mean alveolar size leads to improved diagnosis of emphysema in lung radiographs.
Readily releasable pool of synaptic vesicles measured at single synaptic contacts
Authors: Trigo Federico F. , Sakaba Takeshi , Ogden David , Marty Alain
Published: October 2012

To distinguish between different models of vesicular release in brain synapses, it is necessary to know the number of vesicles of transmitter that can be released immediately at individual synapses by a high-calcium stimulus, the readily releasable pool (RRP). We used direct stimulation by calcium uncaging at identified, single-site inhibitory synapses to investigate the statistics of vesicular release and the size of the RRP. Vesicular release, detected as quantal responses in the postsynaptic neuron, showed an unexpected stochastic variation in the number of quanta from stimulus to stimulus at high intracellular calcium, with a mean of 1.9 per stimulus and a maximum of three or four. The results provide direct measurement of the RRP at single synaptic sites. They are consistent with models in which release proceeds from a small number of vesicle docking sites with an average occupancy around 0.7.
BapE DNA endonuclease induces an apoptotic-like response to DNA damage in
Caulobacter
Authors: Bos Julia , Yakhnina Anastasiya A. , Gitai Zemer
Published: October 2012

In the presence of extensive DNA damage, eukaryotes activate endonucleases to fragment their chromosomes and induce apoptotic cell death. Apoptotic-like responses have recently been described in bacteria, but primarily in specialized mutant backgrounds, and the factors responsible for DNA damage-induced chromosome fragmentation and death have not been identified. Here we find that wild-type
Caulobacter
cells induce apoptotic-like cell death in response to extensive DNA damage. The bacterial apoptosis endonuclease (BapE) protein is induced by damage but not involved in DNA repair itself, and mediates this cell fate decision. BapE fragments chromosomes by cleaving supercoiled DNA in a sequence-nonspecific manner, thereby perturbing chromosome integrity both in vivo and in vitro. This damage-induced chromosome fragmentation pathway resembles that of eukaryotic apoptosis. We propose that damage-induced programmed cell death can be a primary stress response for some bacterial species, providing isogenic bacterial communities with advantages similar to those that apoptosis provides to multicellular organisms.
Candidate autism gene screen identifies critical role for cell-adhesion molecule CASPR2 in dendritic arborization and spine development
Authors: Anderson Garret R. , Galfin Timothy , Xu Wei , Aoto Jason , Malenka Robert C. , Südhof Thomas C.
Published: October 2012

Mutations in the contactin-associated protein 2 (
CNTNAP2
) gene encoding CASPR2, a neurexin-related cell-adhesion molecule, predispose to autism, but the function of CASPR2 in neural circuit assembly remains largely unknown. In a knockdown survey of autism candidate genes, we found that CASPR2 is required for normal development of neural networks. RNAi-mediated knockdown of CASPR2 produced a cell-autonomous decrease in dendritic arborization and spine development in pyramidal neurons, leading to a global decline in excitatory and inhibitory synapse numbers and a decrease in synaptic transmission without a detectable change in the properties of these synapses. Our data suggest that in addition to the previously described role of CASPR2 in mature neurons, where CASPR2 organizes nodal microdomains of myelinated axons, CASPR2 performs an earlier organizational function in developing neurons that is essential for neural circuit assembly and operates coincident with the time of autism spectrum disorder (ASD) pathogenesis.
Critical frequency as an independent variable in grammaticalization
Authors: Peng Rui
Published: October 2012

In the frequency literature, it has been argued that high text frequency is the motivating factor in grammaticalization. This claim is questionable for two reasons: linguistic items with high frequency do not necessarily undergo grammaticalization, and it is not unusual for grammaticalization to occur to linguistic items with low frequency. The problems are that neither context nor pragmatic inferring has been taken into serious consideration. The development of new grammatical meaning, the defining feature of grammaticalization, takes place only in contexts in which pragmatic inferring is possible. Therefore, depending on the properties of the contexts, frequency may or may not directly trigger the development of new grammaticalization. The more reliable independent variable and catalyst in grammaticalization is “critical frequency,” i.e., the number of occurrences of a grammaticalizing item in contexts with the similar pragmatic inferring conditions.
Five-level classification of clause linkage in Japanese
Authors: Tsunoda Mie
Published: October 2012

On the basis of Japanese data, this paper proposes a five-level classification of clause linkage. Level IV and Level V of this classification correspond to the epistemic domain and the speech-act domain, respectively, of Sweetser’s (1990) classification. Level I corresponds to the content domain of her classification. In addition, the present paper sets up Levels II and III, as distinct from Level I. It shows that different clause-linkage markers (hereafter CLMs) have different distributions in terms of the five levels. For example, some CLMs can be used in all of the five levels. There are also CLMs that are confined to the lower levels, and also those which are limited to the higher levels. Furthermore, some CLMs have a continuous distribution, while others have a discontinuous distribution. Some of the CLMs exhibit different distributions in terms of Levels I, II, and III. This furnishes evidence for setting up Levels II and III, as distinct from Level I and also as distinct from each other.
Judgements about the relation between force and trajectory variables in verbally described ballistic projectile motion
Authors: White Peter A.
Published: October 2012

How accurate are explicit judgements about familiar forms of object motion, and how are they made? Participants judged the relations between force exerted in kicking a soccer ball and variables that define the trajectory of the ball: launch angle, maximum height attained, and maximum distance reached. Judgements tended to conform to a simple heuristic that judged force tends to increase as maximum height and maximum distance increase, with launch angle not being influential. Support was also found for the converse prediction, that judged maximum height and distance tend to increase as the amount of force described in the kick increases. The observed judgemental tendencies did not resemble the objective relations, in which force is a function of interactions between the trajectory variables. This adds to a body of research indicating that practical knowledge based on experiences of actions on objects is not available to the processes that generate judgements in higher cognition and that such judgements are generated by simple rules that do not capture the objective interactions between the physical variables.
Copts in Egypt and their demands: between inclusion and exclusion
Authors: Mogib Mai
Published: October 2012

This work rests on the assumption that to be a Copt is not equivalent to belonging to a specific religious sect. The term Copt refers to all Egyptian Christians. The article is an attempt to analyse the relationship between inclusion and exclusion policies and the nature of the Mubarak regime, the better to explain the nature of economic, social and political factors that led to many conspicuous social and economic imbalances and thence alienation and the appearance of social movements opposed to the state. Taking the Copts as a case study the work demonstrates that demands attributed to and/or defined as those of the Copts specifically are not necessarily an expression of minority or religious concerns so much as general citizen demands. The evidence presented is derived from a major study of the opinion of Coptic citizens towards political and economic demands. The purpose is to determine whether they are considered social, political and economic demands based on citizenship or on religious grounds. The research adopted a set of hypotheses to be confirmed or refuted through compiling and analysing the results of an empirically administered questionnaire.
Forced Labor, Public Policies, and Business Strategies During Franco’s Dictatorship: An Interim Report
Authors: Mendiola Gonzalo Fernando
Published: October 2012

This article presents a balance of the most significant research carried out in Spain on the public policies and business strategies that guided the implementation of different forms of forced labor under Francoism, during both the war and the dictatorship. It deals with the logic and economic impact of this type of punishment, attending to two main aspects. In the first place, the legal organization of forced labor is explained, and emphasis is placed on the role it played in mitigating the shortage of labor power in some sectors. In the second place, the article analyses the profit margins produced by this kind of labor in comparison with free labor, related to productivity levels. In this respect, important differences can be appreciated between work during the war and in the postwar period, as well as between work depending on the army and that of private companies.
The Arabidopsis F-box/Kelch-Repeat Protein At2g44130 Is Upregulated in Giant Cells and Promotes Nematode Susceptibility
Authors: Curtis Rosane H. C. , Pankaj  , Powers Stephen J. , Napier Johnathan , Matthes Michaela C.
Published: October 2012

We report that the F-box/Kelch-repeat protein At2g44130 is specifically induced by the root-knot nematode Meloidogyne incognita during the initial stages of the initiation and maintenance of the feeding site. In addition, we show that the expression of this gene promotes susceptibility of infection because knocking down the F-box gene (At2g44130) drastically reduces nematode attraction to and infection of roots. In contrast, F-box overexpressing (OE) lines had a hypersusceptible phenotype, with an increase of 34% in nematode attraction and 67% in nematode infection when grown in soil. This hypersusceptibility might be the result of an increased attraction of the second-stage juveniles toward root exudates of the F-box OE, which would suggest that the blend of compounds in the root exudates of the OE line was somewhat different from the ones present in the root exudates of the wild type and the F-box knockout and tilling lines. Although the function of the F-box/Kelch-repeat protein (At2g44130) is not known, we postulate that its activation by nematode effectors released during the infection process leads to the formation of SCF(At2g44130) (Skp1-Cullin1-F-box protein) complexes, which are involved in facilitating successful infection by the nematode through targeting specific proteins for degradation.
Iturin Levels on Wheat Spikes Linked to Biological Control of Fusarium Head Blight by Bacillus amyloliquefaciens
Authors: Crane J. M. , Gibson D. M. , Vaughan R. H. , Bergstrom G. C.
Published: October 2012

The TrigoCor strain of Bacillus amyloliquefaciens provides consistent control against Fusarium head blight of wheat in controlled settings but there is a lack of disease and deoxynivalenol suppression in field settings. Since production of antifungal compounds is thought to be the main mode of action of TrigoCor control, we quantified levels of a key family of antifungal metabolites, iturins, as well as monitored Bacillus populations on wheat spikes over 14 days post-application in both the greenhouse and the field. We found that initial iturin levels on spikes in the greenhouse were three times greater than on spikes in the field, but that by 3 days post-application, iturin levels were equivalent and very low in both settings. We also determined that iturins declined rapidly over a 3-day post-application period on wheat spikes in both environments, despite the presence of significant Bacillus populations. Greenhouse trials and antibiosis tests indicated that the lower iturin levels on wheat spikes in the field could be a major factor limiting disease control in field settings. Future efforts to improve Bacillus disease control on wheat spikes and in the phyllosphere of various plants should focus on maintaining higher levels of iturins over critical infection periods.
Learning outdoors: male lizards show flexible spatial learning under semi-natural conditions
Authors: Noble Daniel W. A. , Carazo Pau , Whiting Martin J.
Published: October 2012

Spatial cognition is predicted to be a fundamental component of fitness in many lizard species, and yet some studies suggest that it is relatively slow and inflexible. However, such claims are based on work conducted using experimental designs or in artificial contexts that may underestimate their cognitive abilities. We used a biologically realistic experimental procedure (using simulated predatory attacks) to study spatial learning and its flexibility in the lizard
Eulamprus quoyii
in semi-natural outdoor enclosures under similar conditions to those experienced by lizards in the wild. To evaluate the flexibility of spatial learning, we conducted a reversal spatial-learning task in which positive and negative reinforcements of learnt spatial stimuli were switched. Nineteen (32%) male lizards learnt both tasks within 10 days (spatial task mean: 8.16 ± 0.69 (s.e.) and reversal spatial task mean: 10.74 ± 0.98 (s.e.) trials). We demonstrate that
E. quoyii
are capable of flexible spatial learning and suggest that future studies focus on a range of lizard species which differ in phylogeny and/or ecology, using biologically relevant cognitive tasks, in an effort to bridge the cognitive divide between ecto- and endotherms.
Evidence for behavioural thermoregulation by the world's largest fish
Authors: Thums Michele , Meekan Mark , Stevens John , Wilson Steven , Polovina Jeff
Published: October 2012

Many fishes make frequent ascents to surface waters and often show prolonged surface swimming following descents to deep water. This affinity for the surface is thought to be related to the recovery of body heat lost at depth. We tested this hypothesis using data from time–depth recorders deployed on four whale sharks (
Rhincodon typus
). We summarized vertical movements into bouts of dives and classified these into three main types, using cluster analysis. In addition to day and night ‘bounce’ dives where sharks rapidly descended and ascended, we found a third type: single deep (mean: 340 m), long (mean: 169 min) dives, occurring in daytime with extremely long post-dive surface durations (mean: 146 min). Only sharks that were not constrained by shallow bathymetry performed these dives. We found a negative relationship between the mean surface duration of dives in the bout and the mean minimum temperature of dives in the bout that is consistent with the hypothesis that thermoregulation was a major factor driving use of the surface. The relationship broke down when sharks were diving in mean minimum temperatures around 25°C, suggesting that warmer waters did not incur a large metabolic cost for diving and that other factors may also influence surface use.
To eat and not be eaten: optimal foraging behaviour in suspension feeding copepods
Authors: Kiørboe Thomas , Jiang Houshuo
Published: October 2012

Zooplankton feed on microscopic prey that they either entrain in a feeding current or encounter as they cruise through the water. They generate fluid disturbances as they feed and move, thus elevating their risk of being detected and encountered by predators. Different feeding modes generate different hydrodynamic signals to predators and different predator encounter speeds but may also differ in their efficiency; the optimal behaviour is that which maximizes the net energy gain over the predation risk. Here, we show by means of flow visualization and simple hydrodynamic and optimization models that copepods with a diversity of feeding behaviours converge on optimal, size-independent specific clearance rates that are consistent with observed clearance rates of zooplankton, irrespective of feeding mode, species and size. We also predict magnitudes and size-scaling of swimming speeds that are consistent with observations. The rationalization of the magnitude and scaling of the clearance rates of zooplankton makes it more suitable for development of models of marine ecosystems, and is particularly relevant in predicting the size structure and biomass of pelagic communities.
Dispersion of discontinuous periodic waves
Authors: Chen Gong , Olver Peter J.
Published: October 2012

The dynamic evolution of linearly dispersive waves on periodic domains with discontinuous initial profiles is shown to depend remarkedly upon the asymptotics of the dispersion relation at large wavenumbers. Asymptotically linear or sublinear dispersion relations produce slowly changing waves, while those with polynomial growth exhibit dispersive quantization, a.k.a. the Talbot effect, being (approximately) quantized at rational times, but a non-differentiable fractal at irrational times. Numerical experiments suggest that such effects persist into the nonlinear regime, for both integrable and non-integrable systems. Implications for the successful modelling of wave phenomena on bounded domains and numerical challenges are discussed.
How does climate change cause extinction?
Authors: Cahill Abigail E. , Aiello-Lammens Matthew E. , Fisher-Reid M. Caitlin , Hua Xia , Karanewsky Caitlin J. , Yeong Ryu Hae , Sbeglia Gena C. , Spagnolo Fabrizio , Waldron John B. , Warsi Omar , Wiens John J.
Published: October 2012

Anthropogenic climate change is predicted to be a major cause of species extinctions in the next 100 years. But what will actually cause these extinctions? For example, will it be limited physiological tolerance to high temperatures, changing biotic interactions or other factors? Here, we systematically review the proximate causes of climate-change related extinctions and their empirical support. We find 136 case studies of climatic impacts that are potentially relevant to this topic. However, only seven identified proximate causes of demonstrated local extinctions due to anthropogenic climate change. Among these seven studies, the proximate causes vary widely. Surprisingly, none show a straightforward relationship between local extinction and limited tolerances to high temperature. Instead, many studies implicate species interactions as an important proximate cause, especially decreases in food availability. We find very similar patterns in studies showing decreases in abundance associated with climate change, and in those studies showing impacts of climatic oscillations. Collectively, these results highlight our disturbingly limited knowledge of this crucial issue but also support the idea that changing species interactions are an important cause of documented population declines and extinctions related to climate change. Finally, we briefly outline general research strategies for identifying these proximate causes in future studies.
Maintaining functional major histocompatibility complex diversity under inbreeding: the case of a selfing vertebrate
Authors: Ellison A. , Allainguillaume J. , Girdwood S. , Pachebat J. , Peat K. M. , Wright P. , Consuegra S.
Published: October 2012

Major histocompatibility complex (MHC) genes encode proteins that present pathogen-derived antigens to T-cells, initiating the adaptive immune response in vertebrates. Although populations with low MHC diversity tend to be more susceptible to pathogens, some bottlenecked populations persist and even increase in numbers despite low MHC diversity. Thus, the relative importance of MHC diversity versus genome-wide variability for the long-term viability of populations after bottlenecks and/or under high inbreeding is controversial. We tested the hypothesis that genome-wide inbreeding (estimated using microsatellites) should be more critical than MHC diversity alone in determining pathogen resistance in the self-fertilizing fishKryptolebias marmoratusby analysing MHC diversity and parasite loads in natural and laboratory populations with different degrees of inbreeding. Both MHC and neutral diversities were lost after several generations of selfing, but we also found evidence of parasite selection acting on MHC diversity and of non-random loss of alleles, suggesting a possible selective advantage of those individuals with functionally divergent MHC, in accordance with the hypothesis of divergent allele advantage. Moreover, we found that parasite loads were better explained by including MHC diversity in the model than by genome-wide (microsatellites) heterozygosity alone. Our results suggest that immune-related overdominance could be the key in maintaining variables rates of selfing and outcrossing inK. marmoratusand other mixed-mating species.
Female-specific target sites for both oestrogen and androgen in the teleost brain
Authors: Hiraki Towako , Takeuchi Akio , Tsumaki Takayasu , Zempo Buntaro , Kanda Shinji , Oka Yoshitaka , Nagahama Yoshitaka , Okubo Kataaki
Published: October 2012

To dissect the molecular and cellular basis of sexual differentiation of the teleost brain, which maintains marked sexual plasticity throughout life, we examined sex differences in neural expression of all subtypes of nuclear oestrogen and androgen receptors (ER and AR) in medaka. All receptors were differentially expressed between the sexes in specific nuclei in the forebrain. The most pronounced sex differences were found in several nuclei in the ventral telencephalic and preoptic areas, where ER and AR expression were prominent in females but almost completely absent in males, indicating that these nuclei represent female-specific target sites for both oestrogen and androgen in the brain. Subsequent analyses revealed that the female-specific expression of ER and AR is not under the direct control of sex-linked genes but is instead regulated positively by oestrogen and negatively by androgen in a transient and reversible manner. Taken together, the present study demonstrates that sex-specific target sites for both oestrogen and androgen occur in the brain as a result of the activational effects of gonadal steroids. The consequent sex-specific but reversible steroid sensitivity of the adult brain probably contributes substantially to the process of sexual differentiation and the persistent sexual plasticity of the teleost brain.
Patient and impatient punishers of free-riders
Authors: Espín Antonio M. , Brañas-Garza Pablo , Herrmann Benedikt , Gamella Juan F.
Published: October 2012

Costly punishment of cheaters who contribute little or nothing to a cooperating group has been extensively studied, as an effective means to enforce cooperation. The prevailing view is that individuals use punishment to retaliate against transgressions of moral standards such as fairness or equity. However, there is much debate regarding the psychological underpinnings of costly punishment. Some authors suggest that costly punishment must be a product of humans' capacity for reasoning, self-control and long-term planning, whereas others argue that it is the result of an impulsive, present-oriented emotional drive. Here, we explore the inter-temporal preferences of punishers in a multilateral cooperation game and show that both interpretations might be right, as we can identify two different types of punishment: punishment of free-riders by cooperators, which is predicted by patience (future orientation); and free-riders' punishment of other free-riders, which is predicted by impatience (present orientation). Therefore, the picture is more complex as punishment by free-riders probably comes not from a reaction against a moral transgression, but instead from a competitive, spiteful drive. Thus, punishment grounded on morals may be related to lasting or delayed psychological incentives, whereas punishment triggered by competitive desires may be linked to short-run aspirations. These results indicate that the individual's time horizon is relevant for the type of social behaviour she opts for. Integrating such differences in inter-temporal preferences and the social behaviour of agents might help to achieve a better understanding of how human cooperation and punishment behaviour has evolved.
Person (mis)perception: functionally biased sex categorization of bodies
Authors: Johnson Kerri L. , Iida Masumi , Tassinary Louis G.
Published: October 2012

Social perception is among the most important tasks that occur in daily life, and perceivers readily appreciate the social affordances of others. Here, we demonstrate that sex categorizations are functionally biased towards a male percept. Perceivers judged body shapes that varied in waist-to-hip ratio to be men if they were not, in reality, exclusive to women, and male categorizations occurred more quickly than female categorizations (studies 1 and 4). This pattern was corroborated when participants identified the average body shapes of men and women (study 2) and when we assessed participants' cognitive representations (study 3). Moreover, these tendencies were modulated by emotion context (study 4). Thus, male categorizations occurred readily and rapidly, demonstrating a pronounced categorization bias and temporal advantage for male judgements.
A triple helix stabilizes the 3′ ends of long noncoding RNAs that lack poly(A) tails
Authors: Wilusz Jeremy E. , JnBaptiste Courtney K. , Lu Laura Y. , Kuhn Claus-D. , Joshua-Tor Leemor , Sharp Phillip A.
Published: October 2012

The MALAT1 (metastasis-associated lung adenocarcinoma transcript 1) locus is misregulated in many human cancers and produces an abundant long nuclear-retained noncoding RNA. Despite being transcribed by RNA polymerase II, the 3′ end of MALAT1 is produced not by canonical cleavage/polyadenylation but instead by recognition and cleavage of a tRNA-like structure by RNase P. Mature MALAT1 thus lacks a poly(A) tail yet is expressed at a level higher than many protein-coding genes in vivo. Here we show that the 3′ ends of MALAT1 and the MEN β long noncoding RNAs are protected from 3′–5′ exonucleases by highly conserved triple helical structures. Surprisingly, when these structures are placed downstream from an ORF, the transcript is efficiently translated in vivo despite the lack of a poly(A) tail. The triple helix therefore also functions as a translational enhancer, and mutations in this region separate this translation activity from simple effects on RNA stability or transport. We further found that a transcript ending in a triple helix is efficiently repressed by microRNAs in vivo, arguing against a major role for the poly(A) tail in microRNA-mediated silencing. These results provide new insights into how transcripts that lack poly(A) tails are stabilized and regulated and suggest that RNA triple-helical structures likely have key regulatory functions in vivo.
Olfactory bulb α2-adrenoceptor activation promotes rat pup odor-preference learning via a cAMP-independent mechanism
Authors: Shakhawat Amin MD. , Harley Carolyn W. , Yuan Qi
Published: October 2012

In this study, three lines of evidence suggest a role for α2-adrenoreceptors in rat pup odor-preference learning: olfactory bulb infusions of the α2-antagonist, yohimbine, prevents learning; the α2-agonist, clonidine, paired with odor, induces learning; and subthreshold clonidine paired with subthreshold β-adrenoceptor activation also recruits learning. Increased mitral cell layer pCREB occurs with clonidine-infusion, but cAMP is not increased. Similar results using a GABAa-antagonist suggest that disinhibition may support clonidine-induced learning. We suggest that norepinephrine can act through multiple bulbar adrenoceptor subtypes to induce odor learning and that cAMP-dependent, as well as cAMP-independent, signals may act as unconditioned stimuli.
Two MicroRNAs Linked to Nodule Infection and Nitrogen-Fixing Ability in the Legume Lotus japonicus
Authors: De Luis Ana , Markmann Katharina , Cognat Valérie , Holt Dennis B. , Charpentier Myriam , Parniske Martin , Stougaard Jens , Voinnet Olivier
Published: October 2012

Legumes overcome nitrogen shortage by developing root nodules in which symbiotic bacteria fix atmospheric nitrogen in exchange for host-derived carbohydrates and mineral nutrients. Nodule development involves the distinct processes of nodule organogenesis, bacterial infection, and the onset of nitrogen fixation. These entail profound, dynamic gene expression changes, notably contributed to by microRNAs (miRNAs). Here, we used deep-sequencing, candidate-based expression studies and a selection of Lotus japonicus mutants uncoupling different symbiosis stages to identify miRNAs involved in symbiotic nitrogen fixation. Induction of a noncanonical miR171 isoform, which targets the key nodulation transcription factor Nodulation Signaling Pathway2, correlates with bacterial infection in nodules. A second candidate, miR397, is systemically induced in the presence of active, nitrogen-fixing nodules but not in that of noninfected or inactive nodule organs. It is involved in nitrogen fixation-related copper homeostasis and targets a member of the laccase copper protein family. These findings thus identify two miRNAs specifically responding to symbiotic infection and nodule function in legumes.
The Submergence Tolerance Gene SUB1A Delays Leaf Senescence under Prolonged Darkness through Hormonal Regulation in Rice
Authors: Fukao Takeshi , Yeung Elaine , Bailey-Serres Julia
Published: October 2012

Leaf senescence is a natural age-dependent process that is induced prematurely by various environmental stresses. Typical alterations during leaf senescence include breakdown of chlorophyll, a shift to catabolism of energy reserves, and induction of senescence-associated genes, all of which can occur during submergence, drought, and constant darkness. Here, we evaluated the influence of the submergence tolerance regulator, SUBMERGENCE1A (SUB1A), in the acclimation responses during leaf senescence caused by prolonged darkness in rice (Oryza sativa). SUB1A messenger RNA was highly induced by prolonged darkness in a near-isogenic line containing SUB1A. Genotypes with conditional and ectopic overexpression of SUB1A significantly delayed loss of leaf color and enhanced recovery from dark stress. Physiological analysis revealed that SUB1A postpones dark-induced senescence through the maintenance of chlorophyll and carbohydrate reserves in photosynthetic tissue. This delay allowed leaves of SUB1A genotypes to recover photosynthetic activity more quickly upon reexposure to light. SUB1A also restricted the transcript accumulation of representative senescence-associated genes. Jasmonate and salicylic acid are positive regulators of leaf senescence, but ectopic overexpression of SUB1A dampened responsiveness to both hormones in the context of senescence. We found that ethylene accelerated senescence stimulated by darkness and jasmonate, although SUB1A significantly restrained dark-induced ethylene accumulation. Overall, SUB1A genotypes displayed altered responses to prolonged darkness by limiting ethylene production and responsiveness to jasmonate and salicylic acid, thereby dampening the breakdown of chlorophyll, carbohydrates, and the accumulation of senescence-associated messenger RNAs. A delay of leaf senescence conferred by SUB1A can contribute to the enhancement of tolerance to submergence, drought, and oxidative stress.
The customer satisfaction‐customer loyalty relationship
Authors: Martins Gonçalves Helena , Sampaio Patrícia
Published: October 2012

Purpose

This study aims to examine the moderating effects of gender, income, age, customer involvement and length of the relationship on the customer satisfaction (CS)‐customer loyalty (CL) relationship in a contractual service context. CL is assessed using customer repurchase intention (RI) and repurchase behavior (RB).

Design/methodology/approach

Using a postal mail survey, the authors measure the CS, RI involvement and socio‐demographic characteristics of customers who use a credit card. RB is measured by the number of transactions and the corresponding amount spent by clients, based on data provided by the company. The proposed hypotheses are tested using random sampling and hierarchical regressions.

Findings

The significant moderators are different depending on the CL measure used. When RI is utilized, the gender and age of the client have a positive effect on the CS‐CL relationship. However, when RB is assessed using the number of transactions made by the credit card's owner, the length of the relationship becomes the significant moderator.

Research limitations/implications

The study is limited to a single firm, from one industry sector, but provides future researchers a multitude of replication opportunities.

Practical implications

Demographic and relational variables are important in explaining the CS‐CL relationship. Customer relationship strategies have positive results. RB is preferred to RI when evaluating and explaining CL.

Originality/value

The assessment of customer and relational characteristics as moderating variables in the CS‐CL relationship, and comparing different measures of CL in a contractual service adds value to this research.