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Role
Kinds of Role Terms modified by Role Selected AbstractsTHE ROLE OF CRIME IN HOUSING UNIT RACIAL/ETHNIC TRANSITION,CRIMINOLOGY, Issue 3 2010JOHN R. HIPP Previous research frequently has observed a positive cross-sectional relationship between racial/ethnic minorities and crime and generally has posited that this relationship is entirely because of the effect of minorities on neighborhood crime rates. This study posits that at least some of this relationship might be a result of the opposite effect,neighborhood crime increases the number of racial/ethnic minorities. This study employs a unique sample (the American Housing Survey neighborhood sample) focusing on housing units nested in microneighborhoods across three waves from 1985 to 1993. This format allows one to test and find that such racial/ethnic transformation occurs because of the following effects: First, White households that perceive more crime in the neighborhood or that live in microneighborhoods with more commonly perceived crime are more likely to move out of such neighborhoods. Second, Whites are significantly less likely to move into a housing unit in a microneighborhood with more commonly perceived crime. And third, African American and Latino households are more likely to move into such units. [source] THE ROLE OF PUBLIC SOCIAL CONTROL IN URBAN NEIGHBORHOODS: A MULTILEVEL ANALYSIS OF VICTIMIZATION RISK,CRIMINOLOGY, Issue 4 2001MARÍA B. VÉLEZ This study introduces public social control into multilevel victimization research by investigating its impact on household and personal victimization risk for residents across 60 urban neighborhoods. Public social control refers to the ability of neighborhoods to secure external resources necessary for the reduction of crime and victimization. I find that living in neighborhoods with high levels of public social control reduces an individual's likelihood of victimization, especially in disadvantaged neighborhoods. Given the important role that residents of disadvantaged neighborhoods can play in securing public social control, this contingent finding suggests that disadvantaged neighborhoods can be politically viable contexts. [source] CRIME (CONTROL) IS A CHOICE: DIVERGENT PERSPECTIVES ON THE ROLE OF TREATMENT IN THE ADULT CORRECTIONS SYSTEMCRIMINOLOGY AND PUBLIC POLICY, Issue 2 2005JAMES M. BYRNE [source] EARLY DIAGNOSIS OF SMALL PANCREATIC CANCER: ROLE OF ENDOSCOPIC ULTRASONOGRAPHYDIGESTIVE ENDOSCOPY, Issue 2009Atsushi Irisawa Advanced pancreatic cancer is a major cause of cancer-related death. However, if surgery achieves clear margins and negative lymph nodes, the prognosis for survival can be prolonged. Therefore, early diagnosis , as early as possible , is important for improving overall survival and quality of life in patients with pancreatic cancer. Because of higher imaging resolution near the pancreas through the gastroduodenal wall, endoscopic ultrasonography enables detection of subtle pancreatic abnormalities. In fact, many investigators have reported the high ability of EUS not only for detection of small lesions but also recognition of chronic pancreatitis, which is the risky status of pancreatic cancer. As a tool for early diagnosis of pancreatic cancer, EUS is a highly anticipated modality. [source] ROLE OF ENDOSCOPY IN SCREENING OF EARLY PANCREATIC CANCER AND BILE DUCT CANCERDIGESTIVE ENDOSCOPY, Issue 2009Kiyohito Tanaka In the screening of early pancreatic cancer and bile duct cancer, the first issue was ,what are the types of abnormality in laboratory data and symptoms in case of early pancreatic cancer and bile duct cancer?' Early cancer in the pancreaticobiliary region has almost no symptoms, however epigastralgia without abnormality in the gastrointestinal (GI) tract is a sign of early stage pancreaticobiliary cancer. Sudden onset and aggravation of diabetes mellitus is an important change in the case of pancreatic cancer. Extracorporeal ultrasonography is a very useful procedure of checking up changes of pancreatic and biliary lesions. As the role of endoscopy in screening, endoscopic ultrasonography (EUS) is the most effective means of cancer detection of the pancreas, and endoscopic retrograde cholangiopancreatography (ERCP) is most useful of diagnosis tool for abnormalities of the common bile duct. Endoscopic retrograde cholangiopancreatography is an important modality as the procedure of sampling of diagnostic materials. Endoscopic ultrasonography-fine needle aspiration (EUS-FNA) has the role of histological diagnosis of pancreatic mass lesion also. Especially, in the case of pancreas cancer without evidence of cancer by pancreatic juice cytology and brushing cytology, EUS-FNA is essential. Intra ductal ultrasonography (IUDS) and perotral cholangioscopy (POCS) are useful for determination of mucosal extent in extrahepatic bile duct cancer. Further improvements of endoscopical technology, endoscopic procedures are expected to be more useful modalities in detection and diagnosis of early pancreatic and bile duct cancers. [source] MISGUIDED CORPORATE VIRTUE: THE CASE AGAINST CSR, AND THE TRUE ROLE OF BUSINESS TODAY1ECONOMIC AFFAIRS, Issue 4 2009David Henderson The doctrine of corporate social responsibility (CSR) has now been accepted across the world , not only by businesses and business organisations, together with an array of commentators and NGOs, but also by many governments. This is a worrying development. The doctrine rests on mistaken presumptions about recent economic developments and their implications for the role and conduct of enterprises, while putting it into effect would make the world poorer and more over-regulated. [source] A NEW ROLE FOR CONSUMERS' PREFERENCES IN THE PROVISION OF HEALTHCAREECONOMIC AFFAIRS, Issue 3 2006Harry Telser In the present allocation of resources in healthcare, preferences of consumers as the ultimate financiers of healthcare services are judged to be of little relevance. This state of affairs is being challenged because the past decade has seen great progress in the measurement of preferences, or more precisely, willingness-to-pay (WTP) as applied to healthcare services. This article reports evidence on WTP of the Swiss population with regard to three hypothetical modifications of the drug benefit to be covered by social health insurance: delaying access to the most recent therapeutic innovations (among them, drugs) by two years in exchange for a reduction of the monthly premium; substituting original preparations by generics, again in return for a lowered premium; and the exclusion of preparations for the treatment of minor complaints from the drug benefit. Using discrete-choice experiments, WTP and its determinants are estimated. Average WTP for avoiding such a delay (which acts across the board) is much higher than for eschewing the exclusive use of generics (which are claimed to be largely equivalent to the original) or the retention of ,unimportant' drugs in the list of benefits , a rating predicted by economic theory. In addition, a great deal of preference heterogeneity between the French-speaking minority and the German-speaking majority was found, pointing to considerable efficiency losses caused by uniformity of social health insurance. [source] THE ROLE OF THE BIDDING PROCESS IN PRICE DETERMINATION: JUMP BIDDING IN SEQUENTIAL ENGLISH AUCTIONSECONOMIC INQUIRY, Issue 3 2008YARON RAVIV This paper uses data collected from a series of public auctions of used cars in New Jersey to examine how strategic bidding affects price determination in open-outcry English auctions. "Jumps" in the bidding, which occur when a new offer exceeds the old offer by more than the minimum bid increment, are highly pervasive and consistently related to the item's presale estimated price. The size of the jumps is not affected by the selling order, however. This jump bidding pattern suggests that open-outcry auctions are more appropriately interpreted with models that assume common-item valuations rather than models assuming private valuations. (JEL D44) [source] THE ROLE OF NONCOGNITIVE SKILLS IN EXPLAINING COGNITIVE TEST SCORESECONOMIC INQUIRY, Issue 1 2008LEX BORGHANS This article examines whether noncognitive skills,measured both by personality traits and by economic preference parameters,influence cognitive tests' performance. The basic idea is that noncognitive skills might affect the effort people put into a test to obtain good results. We experimentally varied the rewards for questions in a cognitive test to measure to what extent people are sensitive to financial incentives. To distinguish increased mental effort from extra time investments, we also varied the questions' time constraints. Subjects with favorable personality traits such as high performance motivation and an internal locus of control perform relatively well in the absence of rewards, consistent with a model in which trying as hard as you can is the best strategy. In contrast, favorable economic preference parameters (low discount rate, low risk aversion) are associated with increases in time investments when incentives are introduced, consistent with a rational economic model in which people only invest when there are monetary returns. The main conclusion is that individual behavior at cognitive tests depends on noncognitive skills. (JEL J20, J24) [source] CAFTA, CAMPAIGN CONTRIBUTIONS, AND THE ROLE OF SPECIAL INTERESTSECONOMICS & POLITICS, Issue 3 2010JAMES M. DEVAULT This paper analyzes the passage of the Central American Free Trade Agreement (CAFTA) in 2005, paying particular attention to the role of campaign contributions. The CAFTA vote is significant in that the context in which it occurred was one in which campaign contributions were more likely to influence votes. By more carefully identifying the special interest groups actively involved in the CAFTA debate, I provide a more accurate assessment of the impact of the contributions made by these groups. I use instrumental variables to control for the potential endogeneity of campaign contributions and find that these contributions played at best a secondary role in determining the outcome of the CAFTA vote in the U.S. House of Representatives. [source] ON THE ROLE OF THE PRIMARY SYSTEM IN CANDIDATE SELECTIONECONOMICS & POLITICS, Issue 2 2006MANDAR P. OAK How does the type of the primary system affect political outcomes? We address this issue by constructing a simple model that accounts for intra-party as well as inter-party political competition. Our model suggests that allowing non-partisan voters to participate in the primaries (i.e. a semi-open primary system) indeed improves the chances of a moderate candidate getting elected. However, this need not necessarily happen in the case of a completely open primary system. Under such a system there arise multiple equilibria, some of which may lead to a greater degree of extremism than the closed primary system. Thus, our model contributes to the current debate on the choice of primary systems from an analytical perspective and helps explain some of the empirical findings. [source] MINIMIZING HARM FROM GAMBLING: WHAT IS THE GAMBLING INDUSTRY'S ROLE?ADDICTION, Issue 5 2009MARK D. GRIFFITHS No abstract is available for this article. [source] [Commentary] EMERGING ROLE OF SUPERVISED INJECTING FACILITIES IN HUMAN IMMUNODEFICIENCY VIRUS PREVENTIONADDICTION, Issue 4 2009M.-J. MILLOY No abstract is available for this article. [source] A TEST AND REVIEW OF THE ROLE OF EFFECTIVE POPULATION SIZE ON EXPERIMENTAL SEXUAL SELECTION PATTERNSEVOLUTION, Issue 7 2009Rhonda R. Snook Experimental evolution, particularly experimental sexual selection in which sexual selection strength is manipulated by altering the mating system, is an increasingly popular method for testing evolutionary theory. Concerns have arisen regarding genetic diversity variation across experimental treatments: differences in the number and sex ratio of breeders (effective population size; Ne) and the potential for genetic hitchhiking, both of which may cause different levels of genetic variation between treatments. Such differences may affect the selection response and confound interpretation of results. Here we use both census-based estimators and molecular marker-based estimates to empirically test how experimental evolution of sexual selection in Drosophila pseudoobscura impacts Ne and autosomal genetic diversity. We also consider effects of treatment on X-linked Nes, which have previously been ignored. Molecular autosomal marker-based estimators indicate that neither Ne nor genetic diversity differs between treatments experiencing different sexual selection intensities; thus observed evolutionary responses reflect selection rather than any confounding effects of experimental design. Given the increasing number of studies on experimental sexual selection, we also review the census Nes of other experimental systems, calculate X-linked Ne, and compare how different studies have dealt with the issues of inbreeding, genetic drift, and genetic hitchhiking to help inform future designs. [source] RELATIVE ROLE OF GENETIC DETERMINATION AND PLASTIC RESPONSE DURING ONTOGENY FOR SHELL-SHAPE TRAITS SUBJECTED TO DIVERSIFYING SELECTIONEVOLUTION, Issue 5 2009Paula Conde-Padín We studied the relative role of genetic determination versus plastic response for traits involved in ecological adaptation of two ecotypes of Littorina saxatilis living at different shore levels. To investigate the magnitude of the plastic response across ontogeny, we compared morphological data from individuals grown in the laboratory and taken from the wild at three developmental stages: shelled embryos, juveniles, and adults. The results indicate that most shell shape variation (72,99%) in adaptive traits (globosity and aperture of the shell) is explained by the ecotype irrespective of the growth environment, suggesting that direct genetic determination is the main factor responsible for the process of adaptation in the wild. There was a tendency for the contribution of plasticity to increase over ontogeny but, in general, the direction of the plastic response did not suggest that this was adaptive. [source] RESURRECTING THE ROLE OF TRANSCRIPTION FACTOR CHANGE IN DEVELOPMENTAL EVOLUTIONEVOLUTION, Issue 9 2008Vincent J. Lynch A long-standing question in evolutionary and developmental biology concerns the relative contribution of cis- regulatory and protein changes to developmental evolution. Central to this argument is which mutations generate evolutionarily relevant phenotypic variation? A review of the growing body of evolutionary and developmental literature supports the notion that many developmentally relevant differences occur in the cis -regulatory regions of protein-coding genes, generally to the exclusion of changes in the protein-coding region of genes. However, accumulating experimental evidence demonstrates that many of the arguments against a role for proteins in the evolution of gene regulation, and the developmental evolution in general, are no longer supported and there is an increasing number of cases in which transcription factor protein changes have been demonstrated in evolution. Here, we review the evidence that cis- regulatory evolution is an important driver of phenotypic evolution and provide examples of protein-mediated developmental evolution. Finally, we present an argument that the evolution of proteins may play a more substantial, but thus far underestimated, role in developmental evolution. [source] EVOLUTIONARY DYNAMICS OF A SEXUAL ORNAMENT IN THE HOUSE SPARROW (PASSER DOMESTICUS): THE ROLE OF INDIRECT SELECTION WITHIN AND BETWEEN SEXESEVOLUTION, Issue 6 2008Henrik Jensen The relative contribution of sexual and natural selection to evolution of sexual ornaments has rarely been quantified under natural conditions. In this study we used a long-term dataset of house sparrows in which parents and offspring were matched genetically to estimate the within- and across-sex genetic basis for variation and covariation among morphological traits. By applying two-sex multivariate "animal models" to estimate genetic parameters, we estimated evolutionary changes in a male sexual ornament, badge size, from the contribution of direct and indirect selection on correlated traits within males and females, after accounting for overlapping generations and age-structure. Indirect natural selection on genetically correlated traits in males and females was the major force causing evolutionary change in the male ornament. Thus, natural selection on female morphology may cause indirect evolutionary changes in male ornaments. We observed however no directional phenotypic change in the ornament size of one-year-old males during the study period. On the other hand, changes were recorded in other morphological characters of both sexes. Our analyses of evolutionary dynamics in sexual characters require application of appropriate two-sex models to account for how selection on correlated traits in both sexes affects the evolutionary outcome of sexual selection. [source] THE ROLE OF NATURAL ENEMIES IN THE EXPRESSION AND EVOLUTION OF MIXED MATING IN HERMAPHRODITIC PLANTS AND ANIMALSEVOLUTION, Issue 9 2007Janette A. Steets Although a large portion of plant and animal species exhibit intermediate levels of outcrossing, the factors that maintain this wealth of variation are not well understood. Natural enemies are one relatively understudied ecological factor that may influence the evolutionary stability of mixed mating. In this paper, we aim for a conceptual unification of the role of enemies in mating system expression and evolution in both hermaphroditic animals and plants. We review current theory and detail the potential effects of enemies on fundamental mating system parameters. In doing so, we identify situations in which consideration of enemies alters expectations about the stability of mixed mating. Generally, we find that inclusion of the enemy dimension may broaden conditions in which mixed mating systems are evolutionarily stable. Finally, we highlight avenues ripe for future theoretical and empirical work that will advance our understanding of enemies in the expression and evolution of mixed mating in their hosts/victims, including examination of feedback cycles between victims and enemies and quantification of mating system-related parameters in victim populations in the presence and absence of enemies. [source] MUSEUM SPECIMENS AND PHYLOGENIES ELUCIDATE ECOLOGY'S ROLE IN COEVOLUTIONARY ASSOCIATIONS BETWEEN MITES AND THEIR BEE HOSTSEVOLUTION, Issue 6 2007Pavel B. Klimov Coevolutionary associations between hosts and symbionts (or parasites) are often reflected in correlated patterns of divergence as a consequence of limitations on dispersal and establishment on new hosts. Here we show that a phylogenetic correlation is observed between chaetodactylid mites and their hosts, the long-tongued bees; however, this association manifests itself in an atypical fashion. Recently derived mites tend to be associated with basal bee lineages, and vice versa, ruling out a process of cospeciation, and the existence of mites on multiple hosts also suggests ample opportunity for host shifts. An extensive survey of museum collections reveals a pattern of infrequent host shifts at a higher taxonomic level, and yet, frequent shifts at a lower level, which suggests that ecological constraints structure the coevolutionary history of the mites and bees. Certain bee traits, particularly aspects of their nesting behavior, provide a highly predictive framework for the observed pattern of host use, with 82.1% of taxa correctly classified. Thus, the museum survey and phylogenetic analyses provide a unique window into the central role ecology plays in this coevolutionary association. This role is apparent from two different perspectives,as (a) a constraining force evident in the historical processes underlying the significant correlation between the mite and bee phylogenies, as well as (b) by the highly nonrandom composition of bee taxa that serve as hosts to chaetodactylid mites. [source] TESTING THE ROLE OF INTERSPECIFIC COMPETITION IN THE EVOLUTIONARY ORIGIN OF ELEVATIONAL ZONATION: AN EXAMPLE WITH BUARREMON BRUSH-FINCHES (AVES, EMBERIZIDAE) IN THE NEOTROPICAL MOUNTAINSEVOLUTION, Issue 5 2007Carlos Daniel Cadena Interspecific competition might drive the evolution of ecological niches and result in pairs of formerly competing species segregating along ecological gradients following a process of character displacement. This mechanism has been proposed to account for replacement of related species along gradients of elevation in many areas of the world, but the fundamental issue of whether competition is responsible for the origin of elevational replacements has not been tested. To test hypotheses about the role of interspecific competition in the origin of complementary elevational ranges, I combined molecular phylogenetics, phylogeography, and population genetic analyses on Buarremon torquatus and B. brunneinucha (Aves, Emberizidae), whose patterns of elevational distribution suggest character displacement or ecological release. The hypothesis that elevational distributions in these species changed in opposite directions as a result of competition is untenable because: (1) a historical expansion of the range of B. brunneinucha into areas occupied by B. torquatus was not accompanied by a shift in the elevational range of the former species; (2) when B. brunneinucha colonized the range of B. torquatus, lineages of the latter distributions had already diverged; and (3) historical trends in effective population size do not suggest populations with elevational ranges abutting those of putative competitors have declined as would be expected if competition caused range contractions. However, owing to uncertainty in coalescent estimates of historical population sizes, the hypothesis that some populations of B. torquatus have declined cannot be confidently rejected, which suggests asymmetric character displacement might have occurred. I suggest that the main role of competition in elevational zonation may be to act as a sorting mechanism that allows the coexistence along mountain slopes only of ecologically similar species that differ in elevational distributions prior to attaining sympatry. The contrasting biogeographic histories of B. brunneinucha and B. torquatus illustrate how present-day ecological interactions can have recent origins, and highlights important challenges for testing the hypothesis of character displacement in the absence of data on population history and robust reconstructions of the evolution of traits and geographic ranges. [source] FIELD AND EXPERIMENTAL EVIDENCE FOR COMPETITION'S ROLE IN PHENOTYPIC DIVERGENCEEVOLUTION, Issue 2 2007David W. Pfennig Resource competition has long been viewed as a major cause of phenotypic divergence within and between species. Theory predicts that divergence arises because natural selection favors individuals that are phenotypically dissimilar from their competitors. Yet, there are few conclusive tests of this key prediction. Drawing on data from both natural populations and a controlled experiment, this paper presents such a test in tadpoles of two species of spadefoot toads (Spea bombifrons and S. multiplicata). These two species show exaggerated divergence in trophic morphology where they are found together (mixed-species ponds) but not where each is found alone (pure-species ponds), suggesting that they have undergone ecological character displacement. Moreover, in pure-species ponds, both species exhibit resource polymorphism. Using body size as a proxy for fitness, we found that in pure-species ponds disruptive selection favors extreme trophic phenotypes in both species, suggesting that intraspecific competition for food promotes resource polymorphism. In mixed-species ponds, by contrast, we found that trophic morphology was subject to stabilizing selection in S. multiplicata and directional selection in S. bombifrons. A controlled experiment revealed that the more similar an S. multiplicata was to its S. bombifrons tankmate in resource use, the worse was its performance. These results indicate that S. multiplicata individuals that differ from S. bombifrons would be selectively favored in competition. Our data therefore demonstrate how resource competition between phenotypically similar individuals can drive divergence between them. Moreover, our results indicate that how competition contributes to such divergence may be influenced not only by the degree to which competitors overlap in resource use, but also by the abundance and quality of resources. Finally, our finding that competitively mediated disruptive selection may promote resource polymorphism has potentially important implications for understanding how populations evolve in response to heterospecific competitors. In particular, once a population evolves resource polymorphism, it may be more prone to undergo ecological character displacement. [source] EVOLUTION OF COLOR VARIATION IN DRAGON LIZARDS: QUANTITATIVE TESTS OF THE ROLE OF CRYPSIS AND LOCAL ADAPTATIONEVOLUTION, Issue 7 2004Devi M. Stuart-Fox Abstract Many animal species display striking color differences with respect to geographic location, sex, and body region. Traditional adaptive explanations for such complex patterns invoke an interaction between selection for conspicuous signals and natural selection for crypsis. Although there is now a substantial body of evidence supporting the role of sexual selection for signaling functions, quantitative studies of crypsis remain comparatively rare. Here, we combine objective measures of coloration with information on predator visual sensitivities to study the role of crypsis in the evolution of color variation in an Australian lizard species complex (Ctenophorus decresii). We apply a model that allows us to quantify crypsis in terms of the visual contrast of the lizards against their natural backgrounds, as perceived by potential avian predators. We then use these quantitative estimates of crypsis to answer the following questions. Are there significant differences in crypsis conspicuousness among populations? Are there significant differences in crypsis conspicuousness between the sexes? Are body regions "exposed" to visual predators more cryptic than "hidden" body regions? Is there evidence for local adaptation with respect to crypsis against different substrates? In general, our results confirmed that there are real differences in crypsis conspicuousness both between populations and between sexes; that exposed body regions were significantly more cryptic than hidden ones, particularly in females; and that females, but not males, are more cryptic against their own local background than against the background of other populations. Body regions that varied most in contrast between the sexes and between populations were also most conspicuous and are emphasized by males during social and sexual signaling. However, results varied with respect to the aspect of coloration studied. Results based on chromatic contrast ("hue' of color) provided better support for the crypsis hypothesis than did results based on achromatic contrast ("brightness' of color). Taken together, these results support the view that crypsis plays a substantial role in the evolution of color variation and that color patterns represent a balance between the need for conspicuousness for signaling and the need for crypsis to avoid predation. [source] THE ROLE OF SIZE-SPECIFIC PREDATION IN THE EVOLUTION AND DIVERSIFICATION OF PREY LIFE HISTORIESEVOLUTION, Issue 5 2002Troy Day Abstract Some of the best empirical examples of life-history evolution involve responses to predation. Nevertheless, most life-history theory dealing with responses to predation has not been formulated within an explicit dynamic food-web context. In particular, most previous theory does not explicitly consider the coupled population dynamics of the focal species and its predators and resources. Here we present a model of life-history evolution that explores the evolutionary consequences of size-specific predation on small individuals when there is a trade-off between growth and reproduction. The model explicitly describes the population dynamics of a predator, the prey of interest, and its resource. The selective forces that cause life-history evolution in the prey species emerge from the ecological interactions embodied by this model and can involve important elements of frequency dependence. Our results demonstrate that the strength of the coupling between predator and prey in the community determines many aspects of life-history evolution. If the coupling is weak (as is implicitly assumed in many previous models), differences in resource productivity have no effect on the nature of life-history evolution. A single life-history strategy is favored that minimizes the equilibrium resource density (if possible). If the coupling is strong, then higher resource productivities select for faster growth into the predation size refuge. Moreover, under strong coupling it is also possible for natural selection to favor an evolutionary diversification of life histories, possibly resulting in two coexisting species with divergent life-history strategies. [source] BIOLOGICAL SYSTEMS AND MATERIALS: A REVIEW OF THE FIELD OF BIOMECHANICS AND THE ROLE OF THE SOCIETY FOR EXPERIMENTAL MECHANICSEXPERIMENTAL TECHNIQUES, Issue 2 2006E.N. Brown First page of article [source] INSTITUTIONAL ROLE AND MISSIONHIGHER EDUCATION ABSTRACTS, Issue 4 2009Article first published online: 26 FEB 2010 No abstract is available for this article. [source] THE ROLE OF BACTERIAL SYMBIONTS IN AMINO ACID COMPOSITION OF BLACK BEAN APHIDSINSECT SCIENCE, Issue 3 2003Xue-xia Miao Abstract To evaluate the role of bacterial symbionts (Buchnera spp.) in the black bean aphids (Aphis craccivora Koch), the aphids were treated with the antibiotic, rifampicin, to eliminate their intracellular symbiotic bacteria. Analysis of protein and amino acid concentration in 7-day-old of aposymbiotic aphids showed that the total protein content per mg fresh weight was significantly reduced by 29%, but free amino acid titers were increased by 17%. The ratio of the essential amino acids was in general only around 20% essential amino acids in phloem sap of broad bean, whereas it was 44% and 37% in symbiotic and aposymbiotic aphids, respectively, suggesting that the composition of the free amino acids was unbalanced. For example, the essential amino acid, threonine represented 21.6% of essential amino acids in symbiotic aphids, but it was only 16.7% in aposymbiotic aphids. Likewise, two nonessential amino acids, tyrosine and serine, represented 8.9% and 5.6% of total amino acids in symbiontic aphids, respectively, but they enhanced to 21.1% and 13.6% in aposymbiotic aphids. It seems likely that the elevated free amino acid concentration in aposymbiotic aphids was caused by the limited protein anabolism as the result of the unbalanced amino acid composition. [source] THE ROLE OF TUMOR NECROSIS FACTOR-ALPHA IN COGNITIVE IMPROVEMENT AFTER PEROXISOME PROLIFERATOR-ACTIVATOR RECEPTOR GAMMA AGONIST PIOGLITAZONE TREATMENT IN ALZHEIMER'S DISEASEJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 5 2010Haruo Hanyu MD No abstract is available for this article. [source] BLOOD TRANSFUSIONS IN ELDERLY TRAUMA PATIENTS: IS THERE A ROLE FOR RESTRICTIVE USE?JOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 1 2008Kayla Keuter MPH, PA-C No abstract is available for this article. [source] ROLE OF SATURATED FATTY ACIDS IN LIPASE PRODUCTION , USING PSEUDOMONAS AERUGINOSAJOURNAL OF FOOD BIOCHEMISTRY, Issue 6 2007A.N. SARAVANAN ABSTRACT Complex substrates always induce substantial amount of enzyme production during hydrolysis by microorganisms. In this study, ghee was taken for its saturated fatty acid content and analyzed as an inducer for the production of lipase. With ghee emulsion, the bacterium Pseudomonas aeruginosa at optimal condition produced 60 units/min/L at 72 h. With olive oil emulsion, this organism produced only 41 units/min/L as maximum at 96 h. The saturated fatty acids present in ghee make it a hard substance for hydrolysis, which is the reason for the increased enzyme production. This was evaluated by the iodine number experiment. Ghee can also reduce the production cost whereas the costlier olive oil constitutes 25,50% of the total production cost for a commercial scale. The experimental results showed that the saturated fatty acids play an important role in lipase enzyme induction by P. aeruginosa. The use of ghee is cost-effective; hence, it can be used as a potential inducer for lipase production. PRACTICAL APPLICATIONS Lipases are industrially very important enzymes. They are used in pharmaceutical, food, soap and other industries. In lipase production, olive oil is the main constituent. Comparatively, olive oil is costlier; hence, it increases the production cost of lipase. So, this study was done to replace olive oil with a much cheaper ghee using Pseudomonas aeruginosa. The ghee-containing medium gave a very good result because of the presence of complex saturated fatty acids. The ghee-containing medium produced 60 units/min/L at 72 h. The olive oil medium, which contains mainly unsaturated fatty acids, produced only 41 units/min/L as maximum at 96 h. Hence, in the commercial scale, ghee can reduce raw material cost as well as operation time cost significantly when it is used as substrate. [source] ROLE OF INITIAL MUSCLE pH ON THE SOLUBILITY OF FISH MUSCLE PROTEINS IN WATERJOURNAL OF FOOD BIOCHEMISTRY, Issue 4 2004STEPHEN D. KELLEHER The solubility of the myofibrillar and cytoskeletal proteins in water was determined for the muscle tissue often species offish. The flesh of six white-muscled fish had pH's at the time of processing above pH 6.6 and greater than 80% of their myofibrillar/cytoskeletal proteins were soluble in water. The flesh of three pelagic species and a shark had pH values when processed below 6.6 and the water solubility of their myofibrillar and cytoskeletal proteins was less than 40%. When the washed minced muscle of one of the white-fleshed species, cod, was exposed to low pH, the solubility of its myofibrillar and cytoskeletal proteins decreased substantially. The water solubility of the cod myofibrillar and cytoskeletal proteins could be reestablished by washing the acid-treated cod flesh with neutral salt solutions. It is suggested that pH values below 6.6 modify certain proteins which prevent the water-extractability of the rest of the myofibrillar and cytoskeletal proteins from being expressed. [source] | ||||||||||||||||||||||||||||||||||||||||||||||