bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of climate variability on polar bear (Ursus maritimus) and ringed seal (Pusa hispida) population dynamics
Authors: Rosing-Asvid A
Published: April 2006

Unusually high polar bear (Ursus maritimus Phipps, 1774) predation on ringed seal (Pusa hispida (Schreber, 1775)) pups and increased survival of polar bear cubs during mild springs is documented in published articles. Strong predation on newborn ringed seal pups in early spring, however, is likely to lower the overall energy intake of polar bears if ringed seal pups are their main food, because the energetic value of ringed seal pups increases 7–8 times during the 6 week lactation period. So although hunting success in early spring increases cub survival during the period after den emergence,when they are most vulnerable, it is likely to increase the number of starving bears later in the season. This negative-feedback effect of strong spring predation will not occur in areas where other seal species are abundant during summer, and polar bears in such areas are likely to exhibit population growth during periods with milder springs, at least until the ringed seal population has been depleted. Long time series of population estimates that can be used to test this hypothesis do not exist, but it is strongly supported by catch statistics for polar bears and ringed seals from east Greenland.
Synchrony in the amphibian lymphatic system: evidence for bilateral posterior lymph heart synchrony and cardiac–lymphatic synchrony inRana catesbeianaandBufo marinus
Authors: Coolidge Emily H , MacAulay Marla J , Toews Daniel P
Published: April 2006

Early investigations into amphibian lymph heart function established that lymph heart contractions were synchronous with neither the systemic heart, nor the lungs, nor each other. However, the present study concludes that there is synchronization between the cardiac heart and the lymph hearts and that the posterior lymph hearts in both Rana catesbeiana Shaw, 1802 and Bufo marinus (L., 1758) beat synchronously as well. Pressure peaks were recorded through cannulation of the ischiatic artery and each posterior lymph heart and subsequently analyzed to determine the time differences between arterial diastole and lymph heart systole or between two bilateral lymph heart systoles. Results show that there is clear synchronization between the lymph heart systoles of two bilateral posterior lymph hearts. This lymph heart synchrony is further supported by using Poincaré plot analysis to visually compare the lymph heart inter-beats. Cardiac heart and lymph heart contractions also show a degree of synchronization, even though the lymph hearts beat up to three times as fast as the cardiac heart. These results support the conclusion that synchrony is characteristic of the anuran lymphatic system and that synchronization of the cardiac heart and the lymph hearts could impart an energetic advantage that benefits fluid homeostatic mechanisms.
Examining effects of persistent retroviral infection on fitness and pathogen susceptibility in a natural feline host
Authors: Biek Roman , Ruth Toni K , Murphy Kerry M , Anderson, Jr. Charles R , Poss Mary
Published: April 2006

Many animal populations carry endemic (i.e., permanently present) viruses but few studies have assessed the demographic consequences of these infections under natural conditions. We examined the effects of chronic infection with FIVPco, a feline retrovirus, on the fitness and pathogen susceptibility of its natural host, the cougar (Puma concolor (L., 1771)), in the wild. Based on data obtained through intensive monitoring of 160 cougars from two populations, we estimated survival and different measures of host fecundity of infected and uninfected individuals. In addition, we used serological data collected from 207 cougars to test whether FIVPcopredisposes individuals to a higher probability of infection with other pathogens. We found no evidence for an overall reduction in survival due to FIVPcowhen accounting for other sources of demographic variation (age, sex, and population). There was a consistent but nonsignificant trend towards poorer reproductive performance in FIVPco-infected females. We found no serological evidence for a higher probability of secondary infections associated with FIVPco. Overall, these results support the premise that chronic FIVPcoinfection is asymptomatic in its natural cougar host, probably because of a long evolutionary association between virus and host. However, results of stochastic simulations indicate that only larger reductions in annual survival (>20%) can be excluded with confidence. Also, the possibility of a so far unrecognized cost of FIVPcoinfection on cougar fecundity remains.
Major components of grizzly bear diet across North America
Authors: Mowat Garth , Heard Douglas C
Published: April 2006

We measured stable carbon and nitrogen isotope ratios in guard hair of 81 populations of grizzly bears (Ursus arctos L., 1758) across North America and used mixing models to assign diet fractions of salmon, meat derived from terrestrial sources, kokanee (Oncorhynchus nerka (Walbaum in Artedi, 1792)), and plants. In addition, we examined the relationship between skull size and diet of bears killed by people in British Columbia. The majority of carbon and nitrogen assimilated by most coastal grizzly bear populations was derived from salmon, while interior populations usually derived a much smaller fraction of their nutrients from salmon, even in areas with relatively large salmon runs. Terrestrial prey was a large part of the diet where ungulates were abundant, with the highest fractions observed in the central Arctic, where caribou (Rangifer tarandus (L., 1758)) were very abundant. Bears in some boreal areas, where moose (Alces alces (L., 1758)) were abundant, also ate a lot of meat. Bears in dryer areas with low snowfall tended to have relatively high meat diet fractions, presumably because ungulates are more abundant in such environments. Kokanee were an important food in central British Columbia. In areas where meat was more than about a third of the diet, males and females had similar meat diet fractions, but where meat was a smaller portion of the diet, males usually had higher meat diet fractions than females. Females reached 95% of their average adult skull length by 5 years of age, while males took 8 years. Skull width of male grizzly bears increased throughout life, while this trend was slight in females. Skull size increased with the amount of salmon in the diet, but the influence of terrestrial meat on size was inconclusive. We suggest that the amount of salmon in the diet is functionally related to fitness in grizzly bears.
Interspecific aggression and behavioural dominance among four sympatric species of shrews
Authors: Rychlik Leszek , Zwolak Rafal
Published: April 2006

Level of interspecific aggression should reflect intensity of interference competition, and large dominant and small subordinate species should develop aggressive and passive agonistic behaviours, respectively, to achieve stable coexistence. We tested these ideas, investigating interspecific behavioural dominance in a four-species community of shrews varying in body size (Sorex minutus L., 1766; Sorex araneus L., 1758; Neomys anomalus Cabrera, 1907; Neomys fodiens (Pennant, 1771)) by placing interspecific pairs in a neutral field. The order of dominance (determined on the basis of duration of offensive and defensive behaviours, total time spent in the shelter, and a "final shelter resident" index) corresponded to the order of body size: N. fodiens > N. anomalus > S. araneus > S. minutus. The highest number of conflicts and the least pronounced dominance of N. anomalus over S. araneus suggest that the interference competition was strongest between these species. The different social organization of N. anomalus (tolerant and gregarious versus intolerant and solitary in the other three species) did not decrease its aggressiveness and dominance rank. The larger Neomys species were more aggressive and initiated relatively more offensive behaviours, whereas the smaller Sorex species initiated more defensive behaviours. The presence of food and shelter did not intensify conflicts. Nevertheless, dominant species restricted the access of subordinate species to the shelter.
PROGRESS ON WIDELY-TUNABLE MONOCHROMATIC THz SOURCES AND ROOM-TEMPERATURE DETECTIONS OF THz WAVES
Authors: DING YUJIE J. , SHI WEI
Published: April 2006

We have further developed widely-tunable monochromatic THz sources. These sources are based on difference-frequency generation (DFG) in GaSe and GaP crystals. Using a 47 mm long GaSe crystal the output wavelength was tuned in the range from 66.5 to 5664 μm (from 150 to 1.77 cm-1) with the peak powers reaching 389 W. This record-high power corresponds to a conversion efficiency of ~0.1%. On the other hand, using a 20 mm long GaP crystal the output wavelength was tuned in the range 71.1–2830 μm whereas the highest peak power was 15.6 W. The advantage of using GaP over GaSe is obvious: crystal rotation is no longer required for wavelength tuning. Instead, one just needs to tune the wavelength of one mixing beam within the bandwidth of as narrow as 15.3 nm. Most recently, we implemented a new scheme for detecting THz waves based on upconversion at room temperature, i.e. by mixing the THz wave with an infrared laser beam, we observed the upconverted signal at a wavelength just slightly longer than that of the infrared laser. To date the detectable THz power is just an order of magnitude higher than that for a bolometer. This scheme allows us to measure the pulse energy density, wavelength, linewidth, and pulse width of a THz beam at room temperature. Using our widely-tunable monochromatic THz beam, we directly measured the absorption spectra of three different families of the homologues of the chemical vapors.
SPONTANEOUS EMISSION OF NANO-ENGINEERED FLUOROPHORES IN PHOTONIC CRYSTALS
Authors: SONG KAI , VALLEE RENAUD , VAN DER AUWERAER MARK , CLAYS KOEN
Published: April 2006

The spontaneous emission of fluorophores embedded in a photonic crystal has been studied. By nano-engineering a sandwich-like photonic structure, such that fluorophore-coated photonic atoms constitute a middle layer between the photonic crystals, we have been able to precisely control the location of fluorophores in photonic crystals and exclude the presence of fluorophores at the surface of the crystal. It has been found that the stopband in the transmission spectrum is deeper than the stopband in the emission spectrum. We conjecture that the omnidirectional propagation of the emission from a point source in an incomplete photonic bandgap is the cause of the shallower stopband in emission.
NEMATICONS AND THEIR ANGULAR STEERING
Authors: ASSANTO G. , UMETON C. , PECCIANTI M. , ALBERUCCI A.
Published: April 2006

Extraordinary-wave nematicons can be launched and steered in angle by acting on the applied voltage. In specifically designed glass cells for planarly aligned nematic liquid crystals, their direction of propagation can be externally-controlled over angles as large as seven degrees.
INNOVATION IN HEAVY CONSTRUCTION EQUIPMENT MANUFACTURING: AN EXPLORATORY STUDY
Authors: MILLSON MURRAY R. , WILEMON DAVID
Published: April 2006

This research investigates three major hypotheses important to new product market success in the heavy construction equipment industry which are as follows: the greater the degree of organisational integration during the development of new products, the greater will be the market success of new products; the greater the degree of organisational integration during the development of new products, the greater will be the proficiency with which new product development activities are performed; and the greater the proficiency with which new product development activities are performed, the greater will be the new product's success in the marketplace. Information was obtained concerning the most and least successful new products of U.S. firms in the heavy construction equipment industry. "Organisational integration" is defined as the degree of cooperation and communication between internal and external new product development (NPD) "support" groups and NPD teams. "NPD process proficiency" is defined as how well new product development stages and the NPD process as a whole are performed. "New product market success" is represented by four measures that encompass profit expectations, sales expectations, success entering new markets and entering existing markets with new products successfully. The survey approach was utilised to obtain data. Questionnaires were mailed to recipients such as New Product Development Managers who had already been designated by executives of the sample firms. A number of important findings were uncovered during this research. The integration between an organisation's customers and an NPD team is important to the success of newly developed heavy construction equipment products. However, the integration between organisations that supply material, components, assemblies and fabrications to new heavy construction equipment developers was found to hinder the market success of newly developed heavy construction equipment. These and other findings suggest several important implications for product development managers and scholars.
Biochemistry of Mammalian Peroxisomes Revisited
Authors: Wanders Ronald J.A. , Waterham Hans R.
Published: April 2006

In this review, we describe the current state of knowledge about the biochemistry of mammalian peroxisomes, especially human peroxisomes. The identification and characterization of yeast mutants defective either in the biogenesis of peroxisomes or in one of its metabolic functions, notably fatty acid beta-oxidation, combined with the recognition of a group of genetic diseases in man, wherein these processes are also defective, have provided new insights in all aspects of peroxisomes. As a result of these and other studies, the indispensable role of peroxisomes in multiple metabolic pathways has been clarified, and many of the enzymes involved in these pathways have been characterized, purified, and cloned. One aspect of peroxisomes, which has remained ill defined, is the transport of metabolites across the peroxisomal membrane. Although it is clear that mammalian peroxisomes under in vivo conditions are closed structures, which require the active presence of metabolite transporter proteins, much remains to be learned about the permeability properties of mammalian peroxisomes and the role of the four half ATP-binding cassette (ABC) transporters therein.
The Biochemistry of Sirtuins
Authors: Sauve Anthony A. , Wolberger Cynthia , Schramm Vern L. , Boeke Jef D.
Published: April 2006

Sirtuins are a family of NAD+-dependent protein deacetylases widely distributed in all phyla of life. Accumulating evidence indicates that sirtuins are important regulators of organism life span. In yeast, these unique enzymes regulate gene silencing by histone deacetylation and via formation of the novel compound 2′-O-acetyl-ADP-ribose. In multicellular organisms, sirtuins deacetylate histones and transcription factors that regulate stress, metabolism, and survival pathways. The chemical mechanism of sirtuins provides novel opportunities for signaling and metabolic regulation of protein deacetylation. The biological, chemical, and structural characteristics of these unusual enzymes are discussed in this review.
Dynamic Filaments of the Bacterial Cytoskeleton
Authors: Michie Katharine A. , Löwe Jan
Published: April 2006

Bacterial cells contain a variety of structural filamentous proteins necessary for the spatial regulation of cell shape, cell division, and chromosome segregation, analogous to the eukaryotic cytoskeletal proteins. The molecular mechanisms by which these proteins function are beginning to be revealed, and these proteins show numerous three-dimensional structural features and biochemical properties similar to those of eukaryotic actin and tubulin, revealing their evolutionary relationship. Recent technological advances have illuminated links between cell division and chromosome segregation, suggesting a higher complexity and organization of the bacterial cell than was previously thought.
Structure and Mechanism of the Hsp90 Molecular Chaperone Machinery
Authors: Pearl Laurence H. , Prodromou Chrisostomos
Published: April 2006

Heat shock protein 90 (Hsp90) is a molecular chaperone essential for activating many signaling proteins in the eukaryotic cell. Biochemical and structural analysis of Hsp90 has revealed a complex mechanism of ATPase-coupled conformational changes and interactions with cochaperone proteins, which facilitate activation of Hsp90's diverse “clientele.” Despite recent progress, key aspects of the ATPase-coupled mechanism of Hsp90 remain controversial, and the nature of the changes, engendered by Hsp90 in client proteins, is largely unknown. Here, we discuss present knowledge of Hsp90 structure and function gleaned from crystallographic studies of individual domains and recent progress in obtaining a structure for the ATP-bound conformation of the intact dimeric chaperone. Additionally, we describe the roles of the plethora of cochaperones with which Hsp90 cooperates and growing insights into their biochemical mechanisms, which come from crystal structures of Hsp90 cochaperone complexes.
BIOMECHANICAL CONSIDERATIONS IN THE DESIGN OF GRAFT: THE HOMEOSTASIS HYPOTHESIS
Authors: Kassab Ghassan S. , Navia José A.
Published: April 2006

Since its inception in the 1960s, coronary artery bypass graft (CABG) evolved as one of the most common, best documented, and most effective of all major surgical treatments for ischemic heart disease. Despite its widespread use, however, the outcome is not always completely satisfactory. The objective of this review is to highlight the physical determinants of biomechanical design of CABG so that future procedures would have prolonged patency and better outcome. Our central axiom postulates the existence of a mechanical homeostatic state of the blood vessel, i.e., the variation in vessel wall stresses and strains are relatively small under physiological conditions. Any perturbation of mechanical homeostasis leads to growth and remodeling. In this sense, stenosis and failure of a graft may be viewed as an adaptation process gone awry. We outline the principles of engineering design and discuss the biofluid and biosolid mechanics principles that may have the greatest bearing on mechanical homeostasis and the long-term outcome of CABG.
ANALYSIS OF INFLAMMATION
Authors: Schmid-Schönbein Geert W.
Published: April 2006

In the past, inflammation has been associated with infections and with the immune system. But more recent evidence suggests that a much broader range of diseases have telltale markers for inflammation. Inflammation is the basic mechanism available for repair of tissue after an injury and consists of a cascade of cellular and microvascular reactions that serve to remove damaged and generate new tissue. The cascade includes elevated permeability in microvessels, attachment of circulating cells to the vessels in the vicinity of the injury site, migration of several cell types, cell apoptosis, and growth of new tissue and blood vessels. This review provides a summary of the major microvascular, cellular, and molecular mechanisms that regulate elements of the inflammatory cascade. The analysis is largely focused on the identification of the major participants, notably signaling and adhesion molecules, and their mode of action in the inflammatory cascade. We present a new hypothesis for the generation of inflammatory mediators in plasma that are derived from the digestive pancreatic enzymes responsible for digestion. The inflammatory cascade offers a large number of opportunities for development of quantitative models that describe various aspects of human diseases.
GLYCOMICS APPROACH TO STRUCTURE-FUNCTION RELATIONSHIPS OF GLYCOSAMINOGLYCANS
Authors: Sasisekharan Ram , Raman Rahul , Prabhakar Vikas
Published: April 2006

Extracellular modulation of phenotype is an emerging paradigm in this current postgenomics age of molecular and cell biology. Glycosaminoglycans (GAGs) are primary components of the cell surface and the cell–extracellular matrix (ECM) interface. Advances in the technology to analyze GAGs and in whole-organism genetics have led to a dramatic increase in the known important biological role of these complex polysaccharides. Owing to their ubiquitous distribution at the cell-ECM interface, GAGs interact with numerous proteins and modulate their activity, thus impinging on fundamental biological processes such as cell growth and development. Many recent reviews have captured important aspects of GAG structure and biosynthesis, GAG-protein interactions, and GAG biology. GAG research is currently at a stage where there is a need for an integrated systems or glycomics approach, which involves an integration of all of the above concepts to define their structure-function relationships. Focusing on heparin/heparan (HSGAGs) and chondroitin/dermatan sulfate (CSGAGs), this review highlights the important aspects of GAGs and summarizes these aspects in the context of taking a glycomics approach that integrates the different technologies to define structure-function relationships of GAGs.
HYDROGEN IN SEMICONDUCTORS
Authors: Van de Walle Chris G. , Neugebauer Jörg
Published: April 2006

▪ Abstract  Hydrogen strongly affects the properties of electronic materials. Interstitial monatomic hydrogen is always electrically active and usually counteracts the prevailing conductivity of the semiconductor. In some materials, however, hydrogen acts as a source of doping. We describe the mechanisms that govern interactions between hydrogen and semiconductors, including monatomic hydrogen, hydrogen molecules, and hydrogen-related complexes. We also discuss the behavior of hydrogen on the surface and its role in the growth process. The fundamental principles are illustrated with practical examples, many of them for the technologically relevant case of gallium nitride.
PROGRESS IN PLASTIC ELECTRONICS DEVICES
Authors: Singh Th. Birendra , Sariciftci Niyazi Serdar
Published: April 2006

▪ Abstract  Organic field-effect transistors (OFETs) based on solution-processible polymeric as well as small molecular semiconductors have shown impressive improvements in their performance during recent years. These devices have been developed to realize low-cost, large-area electronic products. This review gives an overview of the materials’ aspect, charge-transport, and device physics of OFETs, focusing mainly on the organic semiconductor and organic dielectric materials and their mutual interface. Recent developments in the understanding of the relationship between microstructure and charge transport, the influence of processing techniques, and gate dielectric are reviewed. Comparative data of charge-carrier mobility of most organic semiconductors have been compiled. Ambipolar charge transport in OFETs and its applications to integrated circuits as well as ambipolar light-emitting transistors are also reviewed. Many interesting questions regarding how the molecular and electronic structures at the interface of the organic semiconductor and organic insulator influence device performance and stability remain to be explored.
SYNTHESIS OF COLLOIDAL PARTICLES IN MINIEMULSIONS
Authors: Landfester K.
Published: April 2006

▪ Abstract  Miniemulsions are specially formulated heterophase systems in which stable nanodroplets of one phase are dispersed in a second, continuous phase. Because each of the nanodroplets can be regarded as a nanoscopic, individual batch reactor, a whole variety of reactions and processes resulting in both organic and inorganic nanoparticles can be performed. This chapter reviews the wide range of possibilities of reactions in miniemulsions for the formation of structured nanoparticles. Different kinds of polymerizations, such as radical, anionic, and enzymatic polymerization, as well as polyaddition and polycondensation can be carried out in the nanodroplets, which permits the formulation of a variety of polymers, copolymers, or hybrid particles that previously have not been synthesized in other heterophase processes. Additionally, this review shows that miniemulsions are also highly suited for the encapsulation of various organic and inorganic, solid or liquid materials and for the functionalization of the particle surface.
FERROELASTIC DOMAIN STRUCTURE AND SWITCHING IN EPITAXIAL FERROELECTRIC THIN FILMS
Authors: Lee Kilho , Baik Sunggi
Published: April 2006

▪ Abstract  Unique ferroelastic polytwin domains are formed in epitaxial ferroelectric thin films prepared on single-crystal substrates and critically influence various ferroelectric properties. This chapter reviews theoretical as well as experimental studies on various thermomechanical strain factors and their relaxation involved in domain formation and switching during film processing and device fabrication and application. Two major strain relaxation mechanisms, misfit strain relaxation by dislocations and the formation of polytwin structures, are reviewed. The critical factors controlling the final domain structures, such as substrate selection, film composition, film thickness, introduction of an interlayer, and the lateral size of film patterning, are described in detail. This chapter also includes recent experimental evidence of ferroelastic domain switching in such highly confined epitaxial thin films as well as in small islands.
IN SITU SYNCHROTRON X-RAY STUDIES OF FERROELECTRIC THIN FILMS
Authors: Fong Dillon D. , Thompson Carol
Published: April 2006

▪ Abstract  This paper reviews recent in situ studies of ferroelectric thin films using synchrotron X-ray scattering, with an emphasis on single-crystal perovskite films. We describe observations of thin film growth, the ferroelectric phase transition, and structural evolution during ferroelectric switching. The importance of quantitatively characterizing the internal structure of ferroelectric films under controlled electrical and mechanical boundary conditions is discussed.
NEUROTROPHINS: Mediators and Modulators of Pain
Authors: Pezet Sophie , McMahon Stephen B.
Published: April 2006

The neurotrophin family of neurotrophic factors are well-known for their effects on neuronal survival and growth. Over the past decade, considerable evidence has accumulated from both humans and animals that one neurotrophin, nerve growth factor (NGF), is a peripheral pain mediator, particularly in inflammatory pain states. NGF is upregulated in a wide variety of inflammatory conditions, and NGF-neutralizing molecules are effective analgesic agents in many models of persistent pain. Such molecules are now being evaluated in clinical trials. NGF regulates the expression of a second neurotrophin, brain-derived neurotrophic factor (BDNF), in nociceptors. BDNF is released when nociceptors are activated, and it acts as a central modulator of pain. The chapter reviews the evidence for these roles (and briefly the effects of other neurotrophins), the range of conditions under which they act, and their mechanism of action.
CORTICAL ALGORITHMS FOR PERCEPTUAL GROUPING
Authors: Roelfsema Pieter R.
Published: April 2006

A fundamental task of vision is to group the image elements that belong to one object and to segregate them from other objects and the background. This review provides a conceptual framework of how perceptual grouping may be implemented in the visual cortex. According to this framework, two mechanisms are responsible for perceptual grouping: base-grouping and incremental grouping. Base-groupings are coded by single neurons tuned to multiple features, like the combination of a color and an orientation. They are computed rapidly because they reflect the selectivity of feedforward connections. However, not all conceivable feature combinations are coded by dedicated neurons. Therefore, a second, flexible form of grouping is required called incremental grouping. Incremental grouping enhances the responses of neurons coding features that are bound in perception, but it takes more time than does base-grouping because it relies also on horizontal and feedback connections. The modulation of neuronal response strength during incremental grouping has a correlate in psychology because attention is directed to those features that are labeled by the enhanced neuronal response.
Food Allergies: Prevalence, Molecular Characterization, and Treatment/Prevention Strategies
Authors: Lee Laurie A. , Burks A. Wesley
Published: April 2006

▪ Abstract  A significant proportion of the population is either affected by or concerned about food allergy. Our knowledge about food allergens and how they stimulate the immune system has increased dramatically over the past decade. However, reasons for the increased prevalence of food allergy are not clear. The diagnosis of food allergy requires that the patient and caregivers examine all foods for the presence of potential allergens in order to prevent inadvertent ingestion and further reactions. Fortunately, many children develop tolerance to allergenic foods after a period of dietary elimination. Various immunotherapy approaches are under investigation to alleviate or prevent food-induced reactions in those who have persistent food allergies.
Genetics of Food Intake and Eating Behavior Phenotypes in Humans
Authors: Rankinen Tuomo , Bouchard Claude
Published: April 2006

▪ Abstract  This review summarizes the research advances of the past decade regarding the role of human genetic differences in energy and nutrient intake as well as in eating behavior phenotypes and selected eating disorders. The evidence for familial aggregation and heritability based on twin and nuclear family study designs is summarized. Genome-wide linkage scans and quantitative trait loci identified to date are discussed. DNA sequence variants in candidate genes are reviewed. Single genes associated with classical eating disorders are also incorporated. Epigenetic events will need to be incorporated in future studies designed to investigate the effects of DNA variants on dietary phenotypes. Understanding the relative contribution of global genetic variation and of DNA sequence variants in specific genes is important in the effort to influence dietary habits in a healthier direction.
A Retrospective of an Unconventionally Trained Plant Pathologist: Plant Diseases to Molecular Plant Pathology
Authors: Ouchi Seiji
Published: April 2006

Abstract  Plant pathology evolved from its mycology-oriented origins into a science dealing with biochemical mechanisms of diseases, along with enhanced crop production through disease control. This retrospective describes first my personal experience from my introduction to plant pathology, to the establishment of the concept of accessibility as a model pertaining to genetically defined basic compatibility induced by pathogens. I then refer to the development of molecular plant pathology from physiological and biochemical plant pathology fostered by the growth in recombinant technology in the second half of the past century. This progress was best reflected by the U.S.-Japan Seminar Series held at 4–5-year intervals from 1966 to 2003 and documented by publications in major journals of our discipline. These seminars emphasized that progress in science has always been supported by the invention of novel techniques and that knowledge integrated from modern genomics and subsequent proteomics should contribute to the progress of basic life sciences and, more importantly, to the elaboration of rational measures for disease control.
Virus-Vector Interactions Mediating Nonpersistent and Semipersistent Transmission of Plant Viruses
Authors: Ng James C. K. , Falk Bryce W.
Published: April 2006

Abstract  Most plant viruses are absolutely dependent on a vector for plant-to-plant spread. Although a number of different types of organisms are vectors for different plant viruses, phloem-feeding Hemipterans are the most common and transmit the great majority of plant viruses. The complex and specific interactions between Hemipteran vectors and the viruses they transmit have been studied intensely, and two general strategies, the capsid and helper strategies, are recognized. Both strategies are found for plant viruses that are transmitted by aphids in a nonpersistent manner. Evidence suggests that these strategies are found also for viruses transmitted in a semipersistent manner. Recent applications of molecular and cell biology techniques have helped to elucidate the mechanisms underlying the vector transmission of several plant viruses. This review examines the fundamental contributions and recent developments in this area.
Breeding for Disease Resistance in the Major Cool-Season Turfgrasses
Authors: Bonos Stacy A. , Clarke Bruce B. , Meyer William A.
Published: April 2006

Abstract  Over the past several decades, breeding cool-season turfgrasses for improved disease resistance has been the focus of many turfgrass breeding programs. This review article discusses the dramatic improvements made in breeding Kentucky bluegrass (Poa pratensis) for resistance to leaf spot (caused by Drechslera poae), stem rust (caused by Puccinia graminis), and stripe smut (caused by Ustilago striiformis); perennial ryegrass (Lolium perenne) for resistance to gray leaf spot (caused by Pyricularia grisea), stem rust and crown rust (caused by Puccinia coronata); tall fescue (Festuca arundinacea) for resistance to brown patch (Rhizoctonia solani) and stem rust; creeping bentgrass (Agrostis stolonifera) for resistance to dollar spot (caused by Sclerotinia homoeocarpa); and fine fescues (Festuca spp.) for improved disease resistance. Historically, the dramatic improvements in disease resistance of the cool-season grasses have been attributed to traditional/conventional breeding techniques; however, it is likely that functional genomics and molecular techniques will play a more significant role in the development of cultivated turfgrasses as the specific genes and mechanisms for disease resistance are identified in the future.
The Role of Ethylene in Host-Pathogen Interactions
Authors: Broekaert Willem F. , Delauré Stijn L. , De Bolle Miguel F.C. , Cammue Bruno P.A.
Published: April 2006

Abstract  The phytohormone ethylene is a principal modulator in many aspects of plant life, including various mechanisms by which plants react to pathogen attack. Induced ethylene biosynthesis and subsequent intracellular signaling through a single conserved pathway have been well characterized. This leads to a cascade of transcription factors consisting of primary EIN3-like regulators and downstream ERF-like transcription factors. The latter control the expression of various effector genes involved in various aspects of systemic induced defense responses. Moreover, at this level significant cross-talk occurs with other defense response pathways controlled by salicylic acid and jasmonate, eventually resulting in a differentiated disease response.
Comparative Genomics Reveals What Makes An Enterobacterial Plant Pathogen
Authors: Toth Ian K. , Pritchard Leighton , Birch Paul R. J.
Published: April 2006

Abstract  The bacterial family Enterobacteriaceae contains some of the most devastating human and animal pathogens, including Escherichia coli, Salmonella enterica and species of Yersinia and Shigella. These are among the best-studied of any organisms, yet there is much to be learned about the nature and evolution of interactions with their hosts and with the wider environment. Comparative and functional genomics have fundamentally improved our understanding of their modes of adaptation to different ecological niches and the genes that determine their pathogenicity. In addition to animal pathogens, Enterobacteriaceae include important plant pathogens, such as Erwinia carotovora subsp. atroseptica (Eca), the first plant-pathogenic enterobacterium to be sequenced ( 20 ). This review focuses on genomic comparisons between Eca and other enterobacteria, with particular emphasis on the differences that exemplify or explain the plant-associated lifestyle(s) of Eca. Horizontal gene transfer in Eca may directly have led to the acquisition of a number of determinants that mediate its interactions, pathogenic or otherwise, with plants, offering a glimpse into its evolutionary divergence from animal-pathogenic enterobacteria.
Cumulative Advantage as a Mechanism for Inequality: A Review of Theoretical and Empirical Developments
Authors: DiPrete Thomas A. , Eirich Gregory M.
Published: April 2006

Although originally developed by R.K. Merton to explain advancement in scientific careers, cumulative advantage is a general mechanism for inequality across any temporal process (e.g., life course, family generations) in which a favorable relative position becomes a resource that produces further relative gains. This review shows that the term cumulative advantage has developed multiple meanings in the sociological literature. We distinguish between these alternative forms, discuss mechanisms that have been proposed in the literature that may produce cumulative advantage, and review the empirical literature in the areas of education, careers, and related life course processes.
Sociological Theories of Human Emotions
Authors: Turner Jonathan H. , Stets Jan E.
Published: April 2006

Over the past three decades, five general theoretical approaches to understanding the dynamics of human emotions have emerged in sociology: dramaturgical theories, symbolic interactionist theories, interaction ritual theories, power and status theories, and exchange theories. We review each of these approaches. Despite the progress made by these theories, several issues remain unresolved: the nature of emotions, feeling, and affect; the degree to which emotions are biologically based or socially constructed; the gap between social psychological theories on emotions and macrostructural theorizing; and the relatively narrow range of emotions theorized, coupled with an equally narrow focus on the structural and cultural conditions producing these emotions.
The Rise of Religious Fundamentalism
Authors: Emerson Michael O. , Hartman David
Published: April 2006

Religious fundamentalism has risen to worldwide prominence since the 1970s. We review research on fundamentalist movements to learn what religious fundamentalisms are, if and why they appear to be resurging, their characteristics, their possible links to violence, and their relation to modernity. Surveying work over the past two decades, we find both substantial progress in sociological research on such movements and major holes in conceptualizing and understanding religious fundamentalism. We consider these weaknesses and suggest where research might next be directed.
Voters, Satisficing, and Policymaking: Recent Directions in the Study of Electoral Politics
Authors: Brooks Clem
Published: April 2006

Elections matter for democratic polities, creating linkages between voters, elected officials, and policymaking. These linkages have often been challenging to study empirically owing to the limited availability of suitable data with which to link individual-level voting to aggregate-level policymaking, and also to enduring controversies in the study of mass political behavior. I discuss several new research programs that have begun to advance scholarly understanding of these political linkages. Underlying this work is progress in understanding the microfoundations of voting behavior, coupled with new analytical models of aggregate preferences. Following a discussion of these issues, I consider several innovative strains of research on opinion-policy linkages. This scholarship has significant potential for advancing empirical democratic theory and the study of linkages between voting behavior and other political processes.
Enhancement of substrate-gated Cl− currents via rat glutamate transporter EAAT4 by PMA
Authors: Fang Hongyu , Huang Yueming , Zuo Zhiyi
Published: April 2006

Glutamate transporters (also called excitatory amino acid transporters, EAAT) are important in extracellular homeostasis of glutamate, a major excitatory neurotransmitter. EAAT4, a neuronally expressed EAAT in cerebellum, has a large portion (∼95% of the total l-aspartate-induced currents in human EAAT4) of substrate-gated Cl− currents, a distinct feature of this EAAT. We cloned EAAT4 from rat cerebellum. This molecule was predicted to have eight putative transmembrane domains. l-Glutamate induced an inward current in oocytes expressing this EAAT4 at a holding potential −60 mV. Phorbol 12-myristate 13-acetate (PMA), a protein kinase C (PKC) activator, significantly increased the magnitude of l-glutamate-induced currents but did not affect the apparent affinity of EAAT4 for l-glutamate. This PMA-enhanced current had a reversal potential −17 mV at extracellular Cl− concentration ([Cl−]o) 104 mM with an ∼60-mV shift per 10-fold change in [Cl−]o, properties consistent with Cl−-selective conductance. However, PMA did not change EAAT4 transport activity as measured by [3H]-l-glutamate. Thus PMA-enhanced Cl− currents via EAAT4 were not thermodynamically coupled to substrate transport. These PMA-enhanced Cl− currents were partially blocked by staurosporine, chelerythrine, and calphostin C, the three PKC inhibitors. Ro-31-8425, a PKC inhibitor that inhibits conventional PKC isozymes at low concentrations (nM level), partially inhibited the PMA-enhanced Cl− currents only at a high concentration (1 μM). Intracellular injection of BAPTA, a Ca2+-chelating agent, did not affect the PMA-enhanced Cl− currents. 4α-Phorbol-12,13-didecanoate, an inactive analog of PMA, did not enhance glutamate-induced currents. These data suggest that PKC, possibly isozymes other than conventional ones, modulates the substrate-gated Cl− currents via rat EAAT4. Our results also suggest that substrate-gated ion channel activity and glutamate transport activity, two EAAT4 properties that could modulate neuronal excitability, can be regulated independently.
Measurement of myofilament calcium sensitivity at physiological temperature in intact cardiac trabeculae
Authors: Varian Kenneth D. , Raman Sripriya , Janssen Paul M. L.
Published: April 2006

Cardiac contraction-relaxation coupling is determined by both the free intracellular calcium concentration ([Ca2+]i) and myofilament properties. We set out to develop a technique where we could assess these parameters (twitch and steady-state force [Ca2+]i) under near physiological conditions. Bis-fura-2 was iontophorically introduced into ultrathin rat trabeculae preparations to monitor the [Ca2+]i, and steady-state contractures were achieved by using a modified Krebs-Henseleit solution containing high K+. During K+ contractures, the very slow changes in [Ca2+]i and force development were in equilibrium and allowed for the construction of a steady-state, force-[Ca2+]i relationship. Twitch contractions before and after this myofilament calcium sensitivity assessment were unaltered, and this protocol could be repeated several times. For the first time, this novel protocol allows us to measure myofilament calcium sensitivity under physiological temperature. Not only do the data so obtained allow us to assess myofilament calcium sensitivity, the data also will allow us, in the same preparation under nearly identical conditions, to compare the dynamic to the steady-state, force-calcium relationship. To test whether the steady-state relationship between force and calcium in our novel protocol reproduces expected changes, we determined this relationship in the presence of isoproterenol and under acidosis and alkalosis. As expected, β-adrenergic stimulation resulted in an increase of calcium amplitude and twitch force and a desensitization of the myofilaments as indicated by a rightward shift of the obtained steady-state, force-calcium relationship. An increase in pH shifted the curve leftward, whereas a decrease in pH resulted in the expected rightward shift.
Modifications of proteins by 4-hydroxy-2-nonenal in the ventilatory muscles of rats
Authors: Hussain Sabah N. A. , Matar Ghassan , Barreiro Esther , Florian Maria , Divangahi Maziar , Vassilakopoulos Theodoros
Published: April 2006

Although 4-hydroxy-2-nonenal (HNE, a product of lipid peroxidation) is a major cause of oxidative damage inside skeletal muscles, the exact proteins modified by HNE are unknown. We used two-dimensional electrophoresis, immunoblotting, and mass spectrometry to identify selective proteins targeted by HNE inside the diaphragm of rats under two conditions: severe sepsis [induced by E. coli lipopolysaccharides (LPS)] and during strenuous muscle contractions elicited by severe inspiratory resistive loading (IRL). Diaphragm HNE-protein adduct formation (detected with a polyclonal antibody) increased significantly after 1 and 3 h of LPS injection with a return to baseline values thereafter. Similarly, HNE-protein adduct formation inside the diaphragm rose significantly after 6 but not 3 h of IRL. Mass spectrometry analysis of HNE-modified proteins revealed enolase 3b, aldolase and triosephosphate isomerase 1, creatine kinase, carbonic anyhdrase III, aconitase 2, dihydrolipoamide dehydrogenase, and electron transfer flavoprotein-β. Measurements of in vitro enolase activity in the presence of pure HNE revealed that HNE significantly attenuated enolase activity in a dose-dependent fashion, suggesting that HNE-derived modifications have inhibitory effects on enzyme activity. We conclude that lipid peroxidation products may inhibit muscle contractile performance through selective targeting of enzymes involved in glycolysis, energy production as well as CO2hydration.
S-nitrosothiols regulate cell-surface pH buffering by airway epithelial cells during the human immune response to rhinovirus
Authors: Carraro Silvia , Doherty Joseph , Zaman Khalequz , Gainov Iain , Turner Ronald , Vaughan John , Hunt John F. , Márquez Javier , Gaston Benjamin
Published: April 2006

Human rhinovirus infection is a common trigger for asthma exacerbations. Asthma exacerbations and rhinovirus infections are both associated with markedly decreased pH and ammonium levels in exhaled breath condensates. This observation is thought to be related, in part, to decreased activity of airway epithelial glutaminase. We studied whether direct rhinovirus infection and/or the host immune response to the infection decreased airway epithelial cell surface pH in vitro. Interferon-γ and tumor necrosis factor-α, but not direct rhinovirus infection, decreased pH, an effect partly associated with decreased ammonium concentrations. This effect was 1) prevented by nitric oxide synthase inhibition; 2) independent of cyclic GMP; 3) associated with an increase in endogenous airway epithelial cell S-nitrosothiol concentration; 4) mimicked by the exogenous S-nitrosothiol, S-nitroso-N-acetyl cysteine; and 5) independent of glutaminase expression and activity. We then confirmed that decreased epithelial pH inhibits human rhinovirus replication in airway epithelial cells. These data suggest that a nitric oxide synthase-dependent host response to viral infection mediated by S-nitrosothiols, rather than direct infection itself, plays a role in decreased airway surface pH during human rhinovirus infection. This host immune response may serve to protect the lower airways from direct infection in the normal host. In patients with asthma, however, this fall in pH could be associated with the increased mucus production, augmented inflammatory cell degranulation, bronchoconstriction, and cough characteristic of an asthma exacerbation.