bluuebunny/crossref_metadata_2025 huggingface dataset:
Tax Treaties for Investment and Aid to Sub-saharan Africa: A Case study
Authors: Christians Allison
Published: May 2009

This chapter begins with an overview of the background and function of tax treaties and their proclaimed benefits. It then presents the case study of a hypothetical tax treaty between the United States and Ghana. It shows that such a treaty would produce few tax benefits to current or potential investors and would therefore be largely ineffective in stimulating trade and investment between these two countries. It is argued that after decades of adherence to the promise of tax treaties, we must acknowledge their failure to deliver and search for alternative ways to achieve the goal of promoting aid through the vehicles of investment and trade.
It’s All in the Timing: Assessing the Impact of Bilateral Tax Treaties on U.S. FDI Activity
Authors: Millimet Daniel L. , Kumas Abdullah
Published: May 2009

In light of the important and expanding role of foreign direct investment (FDI) in today's global economy, a vast literature has emerged attempting to uncover the salient factors determining the spatial and temporal pattern of FDI activity. This chapter investigates one potential factor: bilateral tax treaties. The chapter is organized as follows: Section A describes the empirical methodology. Section B discusses the data. Section C presents the results, while Section D concludes.
CHAPTER 6 Rationality and Intransitive Preference
Authors: Anand Paul
Published: May 2009

This chapter provides an overview of what has been called by philosophers the “modern view“ of formal rational choice by focussing on the arguments relating to rational agency and transitive (intransitive) preference. In particular it demonstrates that the logical and semantic arguments are either question‐begging or incomplete. Suggesting that static and dynamic justifications of transitivity are essentially distinct, it identifies a number of problems with the standard money‐pump argument that purports to show why rational agents' preferences are necessarily constrained to have the transitivity property. Subsequently, constructive examples indicating how and when rational agents would want to exhibit intransitive preferences are discussed and finally some of the more recent explicitly game‐theoretic treatments of the argument are discussed. It concludes by suggesting that expected utility should be regarded as a model of context‐free choice, and that a wide range of more general models with the ability to reflect the structure of preference should be seen as modelling rational phenomena.
CHAPTER 7 Dutch Book Arguments
Authors: Hájek Alan
Published: May 2009

Dutch Book arguments purport to show that rationality requires certain constraints on an agent's subjective probabilities, on pain of the agent being susceptible to sure losses in corresponding bets. This survey offers critical assessments of several kinds of Dutch Book arguments. The chapter begins with the classic argument for obedience to the probability calculus, emphasizing both its literal interpretation in terms of monetary losses at the hands of a cunning bettor, and the interpretation that this merely dramatizes a deeper underlying defect, an inconsistency in the agent's credences. The chapter then discusses “diachronic” Dutch Book arguments that concern constraints on how agents should update their credences in the face of evidence. Finally, the chapter canvases some more “exotic” Dutch Book arguments and some recent developments.
CHAPTER 11 Imitation and Learning
Authors: Alós‐Ferrer Carlos , Schlag Karl H.
Published: May 2009

As a learning rule in the context of bounded rationality, imitation is both common and plausible. Its strength is that it relies on minimal information about the environment. In its general form, imitation is nevertheless quite complex since the agent has to specify whom, when and with which propensity to imitate. Some forms of imitation perform well while others do not. This chapter demonstrates, for a variety of different environments, which forms of imitation can be individually or socially desirable. One basic intuition is that when agents within a population face similar choices under uncertainty, imitation can lead to a form of information aggregation. Play within the population serves as a memory of how the different actions performed on average. Special circumstances arise in strategic environments where one may be learning from competing agents. Long‐run predictions of imitative behavior are presented in pure decision problems and strategic settings and related to benchmarks such as evolutionary stability.
CHAPTER 17 Equality and Priority
Authors: Tungodden Bertil
Published: May 2009

The chapter provides an overview of recent economic and philosophical literature on egalitarianism and prioritarianism. it discusses how a concern for equality promotion can be combined with the principle of personal good, and to what extent prioritarian reasoning provides an alternative justification for the worst‐off.
CHAPTER 19 Judgment Aggregation
Authors: List Christian , Puppe Clemens
Published: May 2009

The chapter surveys the recent and fast‐growing literature on the aggregation of logically interrelated propositions, following List and Pettit's formalization of the “doctrinal paradox”. The classical preference aggregation problem is a special case in which propositions take the form of binary preference judgments (“alternative x is better than alternative y”). The first part of the chapter focuses on aggregation methods that satisfy an Arrowian independence condition (“propositionwise aggregation”). In the independent case, the literature has produced a number of general characterization results that precisely demarcate the circumstances in which satisfactory aggregation is possible from those in which it is not Arrow's impossibility theorem and Gibbards oligarchy theorem are special cases of these results. The independence condition is, however, not uncontroversial and the second part of the chapter considers various relaxations of it. Judgment aggregation is still a very active field and the chapter concludes with an outlook on what we believe are important topics for future research.
The Evolution of the Law of Command Responsibility and the Principle of Legality
Authors: Mettraux Guenael
Published: May 2009

This chapter discusses the birth and development of the doctrine of superior responsibility and the part which war crimes tribunals have played in developing and defining that doctrine.
The Resurgence of International Criminal Justice and the Rebirth of Command Responsibility
Authors: Mettraux Guenael
Published: May 2009

This chapter outlines the interaction and interplay between international criminal justice and international criminal law and, in particular, the role that the ad hoc tribunals have played in moulding and fleshing out this doctrine.
Command Responsibility as a Sui Generis Form of Liability for Omission
Authors: Mettraux Guenael
Published: May 2009

This chapter outlines the discussion surrounding the debate over the nature of the doctrine of superior responsibility as a form of criminal liability. It argues that command or superior responsibility constitutes a sui generis form of liability for omission. A superior is, therefore, held criminally responsible for a grave failure (attributable to him) to adopt necessary measures to prevent or punish crimes of subordinates. The chapter also traces the origin of that doctrine in the concept of ‘responsible command’ and discusses the division of labour operated between international law and national law as regard the scope and nature of duties of superiors. It details the nature of the duties that lie upon a superior to act to prevent and punish crimes, and why those duties must be distinguished from those of his subordinates or of that State of which he may be an official. The chapter discusses the necessary relationship that exists between the culpable conduct of the superior and the underlying crimes that form the basis of the charges against him. Finally, it touches upon the question of overlaps between different forms of liability and the important issue of sentencing in cases of superior responsibility.
Scope of Application of the Doctrine of Command Responsibility—International and Internal Conflicts as well as Peacetime?
Authors: Mettraux Guenael
Published: May 2009

This chapter discusses the scope of application of the doctrine of superior responsibility, in particular the question of whether it applies in the context of both international as well as internal armed conflict and whether that doctrine applies, as a matter of international law, to situations where no armed conflict exists.
Trade and the Environment
Authors: Vranes Erich
Published: May 2009

This book deals with a central topic in general international law, WTO law, and international environmental law, namely the relevance of the WTO legal system for environmental protection. The relationship between WTO law and international and domestic efforts to protect the environment has moved to centre stage in WTO and international environmental law. It has also spurred the discussion on fragmentation in international law in recent years. This book analyses these issues by examining the ‘horizontal’ interaction between WTO law and ‘other’ international law, the ‘vertical’ relationship between WTO law and domestic law, and the contents of and interrelations between fundamental provisions of WTO law. This study relies on established insights from legal theory in order to achieve greater clarity in legal argumentation. The main results of this analysis are applied to two topical instances of international regime interplay, namely the relevance of WTO law for international and domestic measures protecting the earth's climate and the ozone layer. A series of controversial topics in WTO and general international law are addressed in this book such as the notion of conflicts of norms and the resolution of conflicts of norms; the role of international law in WTO proceedings; extraterritorial jurisdiction and unilateral trade measures; proportionality and balancing of interests in international and WTO law; the core disciplines of the GATT and the TBT Agreement; process and production-based measures (PPMs) in WTO law; and climate protection, protection of the ozone layer, and WTO disciplines.
Thinking About Nuclear Weapons
Authors: Quinlan Michael
Published: May 2009

This book reflects the author's experience across more than forty years in assessing and helping to shape policy about nuclear weapons, mostly at senior levels close to the centre both of British governmental decision-making and of NATO's development of plans and deployments, with much interaction also with comparable levels of United States activity in the Pentagon and the State Department. From this exceptional background of practical experience Part I of this book seeks to distill basic conceptual ways of understanding the nuclear revolution—the transformation brought about by the existence of nuclear weapons, and their significance in preventing major war. It also surveys NATO's progressive development of thinking about nuclear deterrence, and then discusses the deep moral dilemmas posed—for all possible standpoints—by the existence of such weapons. Part II considers the risks and costs of nuclear-weapon possession, including proliferation dangers, and looks at both successful and unsuccessful ideas for risk-management. Part III illustrates specific issues by reviewing the history and current policies of one long-established possessor, the United Kingdom, and two more recent ones in South Asia. Part IV turns to the future, examines the goal of the eventual abolition of all nuclear armouries, and then discusses the practical agenda, short of such a goal, which governments can usefully tackle in reducing the risks of proliferation and other dangers while not surrendering prematurely the war-prevention benefits which nuclear weapons have brought since 1945.
6 Risks
Authors: Quinlan Michael
Published: May 2009

This chapter reviews a range of risks commonly believed, rightly or wrongly, to arise from the existence of nuclear weapons. It examines first the concept of stability, in two forms—deterrent stability and crisis stability. There follows an extended section on the idea of nuclear escalation, bringing out that though the possibility cannot be wholly excluded and is indeed a component of deterrence, suppositions of its inexorability are unfounded. The next section discusses whether risks of nuclear war by accident, miscalculation, or misunderstanding are substantial, and argues that they are not. The final section looks at the risk of nuclear terrorism. It considers what hurdles a would-be terrorist would have to surmount, and notes ways of keeping such hurdles as high as possible.
9 Easements and Escape Routes
Authors: Quinlan Michael
Published: May 2009

This chapter surveys various radical concepts put forward at one time or another for removing or greatly alleviating the risks and costs of nuclear deterrence. It first discusses the idea of ‘no first use’ promises, and argues that though policy should certainly strive to keep the eventuality of needing to consider first use as remote as possible, formal and unconditional promises cannot be dependable under stress and may even be unhelpful to war-prevention. The next section considers whether there are alternative-defence concepts for effective resistance to a determined nuclear aggressor that need not entail the possession of nuclear weapons, and argues that no universally reliable such possibilities exist. There follows a discussion, again reaching sceptical conclusions, about ideas of ‘minimal’ or ‘virtual’ nuclear armouries. Finally, this chapter recalls President Reagan's 1983 ‘Star Wars’ aspiration to render nuclear weapons entirely impotent by impermeable defence against ballistic missiles, and notes that this aspiration remains unrealistic.
GridPP: the UK grid for particle physics
Authors: Britton D. , Cass A.J. , Clarke P.E.L. , Coles J. , Colling D.J. , Doyle A.T. , Geddes N.I. , Gordon J.C. , Jones R.W.L. , Kelsey D.P. , Lloyd S.L. , Middleton R.P. , Patrick G.N. , Sansum R.A. , Pearce S.E.
Published: May 2009

The start-up of the Large Hadron Collider (LHC) at CERN, Geneva, presents a huge challenge in processing and analysing the vast amounts of scientific data that will be produced. The architecture of the worldwide grid that will handle 15 PB of particle physics data annually from this machine is based on a hierarchical tiered structure. We describe the development of the UK component (GridPP) of this grid from a prototype system to a full exploitation grid for real data analysis. This includes the physical infrastructure, the deployment of middleware, operational experience and the initial exploitation by the major LHC experiments.
Adaptive distributed replica–exchange simulations
Authors: Luckow Andre , Jha Shantenu , Kim Joohyun , Merzky Andre , Schnor Bettina
Published: May 2009

Owing to the loose coupling between replicas, the replica–exchange (RE) class of algorithms should be able to benefit greatly from using as many resources as available. However, the ability to effectively use multiple distributed resources to reduce the time to completion remains a challenge at many levels. Additionally, an implementation of a
pleasingly distributed
algorithm such as replica–exchange, which is independent of infrastructural details, does not exist. This paper proposes an extensible and scalable framework based on Simple API for Grid Applications that provides a general-purpose, opportunistic mechanism to effectively use multiple resources in an infrastructure-independent way. By analysing the requirements of the RE algorithm and the challenges of implementing it on real production systems, we propose a new abstraction (
BigJob
), which forms the basis of the adaptive redistribution and effective scheduling of replicas.
Functional links and robustness in food webs
Authors: Allesina Stefano , Bodini Antonio , Pascual Mercedes
Published: May 2009

The robustness of ecosystems to species losses is a central question in ecology, given the current pace of extinctions and the many species threatened by human impacts, including habitat destruction and climate change. Robustness from the perspective of secondary extinctions has been addressed in the context of food webs to consider the complex network of species interactions that underlie responses to perturbations.
In-silico
removal experiments have examined the structural properties of food webs that enhance or hamper the robustness of ecosystems to species losses, with a focus on the role of hubs, the most connected species. Here we take a different approach and focus on the role of the connections themselves. We show that trophic links can be divided into functional and redundant based on their contribution to robustness. The analysis of empirical webs shows that hubs are not necessarily the most important species as they may hold many redundant links. Furthermore, the fraction of functional connections is high and constant across systems regardless of size and interconnectedness. The main consequence of this scaling pattern is that ecosystem robustness can be considerably reduced by species extinctions even when these do not result in any secondary extinctions. This introduces the possibility of tipping points in the collapse of ecosystems.
Cascading extinctions and community collapse in model food webs
Authors: Dunne Jennifer A. , Williams Richard J.
Published: May 2009

Species loss in ecosystems can lead to secondary extinctions as a result of consumer–resource relationships and other species interactions. We compare levels of secondary extinctions in communities generated by four structural food-web models and a fifth null model in response to sequential primary species removals. We focus on various aspects of food-web structural integrity including robustness, community collapse and threshold periods, and how these features relate to assumptions underlying different models, different species loss sequences and simple measures of diversity and complexity. Hierarchical feeding, a fundamental characteristic of food-web structure, appears to impose a cost in terms of robustness and other aspects of structural integrity. However, exponential-type link distributions, also characteristic of more realistic models, generally confer greater structural robustness than the less skewed link distributions of less realistic models. In most cases for the more realistic models, increased robustness and decreased levels of web collapse are associated with increased diversity, measured as species richness
S
, and increased complexity, measured as connectance
C
. These and other results, including a surprising sensitivity of more realistic model food webs to loss of species with few links to other species, are compared with prior work based on empirical food-web data.
Parasites reduce food web robustness because they are sensitive to secondary extinction as illustrated by an invasive estuarine snail
Authors: Lafferty Kevin D. , Kuris Armand M.
Published: May 2009

A robust food web is one in which few secondary extinctions occur after removing species. We investigated how parasites affected the robustness of the Carpinteria Salt Marsh food web by conducting random species removals and a hypothetical, but plausible, species invasion. Parasites were much more likely than free-living species to suffer secondary extinctions following the removal of a free-living species from the food web. For this reason, the food web was less robust with the inclusion of parasites. Removal of the horn snail,Cerithidea californica, resulted in a disproportionate number of secondary parasite extinctions. The exotic Japanese mud snail,Batillaria attramentaria, is the ecological analogue of the native California horn snail and can completely replace it following invasion. Owing to the similarities between the two snail species, the invasion had no effect on predator–prey interactions. However, because the native snail is host for 17 host-specific parasites, and the invader is host to only one, comparison of a food web that includes parasites showed significant effects of invasion on the native community. The hypothetical invasion also significantly reduced the connectance of the web because the loss of 17 native trematode species eliminated many links.
Food webs: a ladder for picking strawberries or a practical tool for practical problems?
Authors: Memmott Jane
Published: May 2009

While food webs have provided a rich vein of research material over the last 50 years, they have largely been the subject matter of the pure ecologist working in natural habitats. While there are some notable exceptions to this trend, there are, as I explain in this paper, many applied questions that could be answered using a food web approach. The paper is divided into two halves. The first half provides a brief review of six areas where food webs have begun to be used as an applied tool: restoration ecology, alien species, biological control, conservation ecology, habitat management and global warming. The second half outlines five areas in which a food web approach could prove very rewarding: urban ecology, agroecology, habitat fragmentation, cross-habitat food webs and ecosystem services.
The more food webs change, the more they stay the same
Authors: McCann Kevin Shear , Rooney Neil
Published: May 2009

Here, we synthesize a number of recent empirical and theoretical papers to argue that food-web dynamics are characterized by high amounts of spatial and temporal variability and that organisms respond predictably, via behaviour, to these changing conditions. Such behavioural responses on the landscape drive a highly adaptive food-web structure in space and time. Empirical evidence suggests that underlying attributes of food webs are potentially scale-invariant such that food webs are characterized by hump-shaped trophic structures with fast and slow pathways that repeat at different resolutions within the food web. We place these empirical patterns within the context of recent food-web theory to show that adaptable food-web structure confers stability to an assemblage of interacting organisms in a variable world. Finally, we show that recent food-web analyses agree with two of the major predictions of this theory. We argue that the next major frontier in food-web theory and applied food-web ecology must consider the influence of variability on food-web structure.
Predicting invasion success in complex ecological networks
Authors: Romanuk Tamara N. , Zhou Yun , Brose Ulrich , Berlow Eric L. , Williams Richard J. , Martinez Neo D.
Published: May 2009

A central and perhaps insurmountable challenge of invasion ecology is to predict which combinations of species and habitats most effectively promote and prevent biological invasions. Here, we integrate models of network structure and nonlinear population dynamics to search for potential generalities among trophic factors that may drive invasion success and failure. We simulate invasions where 100 different species attempt to invade 150 different food webs with 15–26 species and a wide range (0.06–0.32) of connectance. These simulations yield 11 438 invasion attempts by non-basal species, 47 per cent of which are successful. At the time of introduction, whether or not the invader is a generalist best predicts final invasion success; however, once the invader establishes itself, it is best distinguished from unsuccessful invaders by occupying a lower trophic position and being relatively invulnerable to predation. In general, variables that reflect the interaction between an invading species and its new community, such as generality and trophic position, best predict invasion success; however, for some trophic categories of invaders, fundamental species traits, such as having the centre of the feeding range low on the theoretical niche axis (for non-omnivorous and omnivorous herbivores), or the topology of the food web (for tertiary carnivores), best predict invasion success. Across all invasion scenarios, a discriminant analysis model predicted successful and failed invasions with 76.5 per cent accuracy for properties at the time of introduction or 100 per cent accuracy for properties at the time of establishment. More generally, our results suggest that tackling the challenge of predicting the properties of species and habitats that promote or inhibit invasions from food web perspective may aid ecologists in identifying rules that govern invasions in natural ecosystems.
Food-web structure and ecosystem services: insights from the Serengeti
Authors: Dobson Andy
Published: May 2009

The central organizing theme of this paper is to discuss the dynamics of the Serengeti grassland ecosystem from the perspective of recent developments in food-web theory. The seasonal rainfall patterns that characterize the East African climate create an annually oscillating, large-scale, spatial mosaic of feeding opportunities for the larger ungulates in the Serengeti; this in turn creates a significant annual variation in the food available for their predators. At a smaller spatial scale, periodic fires during the dry season create patches of highly nutritious grazing that are eaten in preference to the surrounding older patches of less palatable vegetation. The species interactions between herbivores and plants, and carnivores and herbivores, are hierarchically nested in the Serengeti food web, with the largest bodied consumers on each trophic level having the broadest diets that include species from a large variety of different habitats in the ecosystem. The different major habitats of the Serengeti are also used in a nested fashion; the highly nutritious forage of the short grass plains is available only to the larger migratory species for a few months each year. The longer grass areas, the woodlands and kopjes (large partially wooded rocky islands in the surrounding mosaic of grassland) contain species that are resident throughout the year; these species often have smaller body size and more specialized diets than the migratory species. Only the larger herbivores and carnivores obtain their nutrition from all the different major habitat types in the ecosystem. The net effect of this is to create a nested hierarchy of subchains of energy flow within the larger Serengeti food web; these flows are seasonally forced by rainfall and operate at different rates in different major branches of the web. The nested structure that couples sequential trophic levels together interacts with annual seasonal variation in the fast and slow chains of nutrient flow in a way that is likely to be central to the stability of the whole web. If the Serengeti is to be successfully conserved as a fully functioning ecosystem, then it is essential that the full diversity of natural habitats be maintained within the greater Serengeti ecosystem. The best way to do this is by controlling the external forces that threaten the boundaries of the ecosystem and by balancing the economic services the park provides between local, national and international needs. I conclude by discussing how the ecosystem services provided by the Serengeti are driven by species on different trophic levels. Tourism provides the largest financial revenue to the national economy, but it could be better organized to provide more sustained revenue to the park. Ultimately, ecotourism needs to be developed in ways that take lessons from the structure of the Serengeti food webs, and in ways that provide tangible benefits to people living around the park while also improving the experience of all visitors.
Dynamics of human papillomavirus serology in women followed up for 36 months after pregnancy
Authors: Syrjänen Stina , Waterboer Tim , Sarkola Marja , Michael Kristina , Rintala Marjut , Syrjänen Kari , Grenman Seija , Pawlita Michael
Published: May 2009

We determined L1 antibodies for human papillomavirus (HPV) types 6, 11, 16, 18 and 45 by multiplex serology in our prospective HPV family study. We report seroprevalence, seroconversion and antibody decay in 290 women (mean age, 25.5 years) sampled before delivery and at 12, 24 and 36 months of follow-up. Multiplex HPV genotyping of the baseline oral and genital scrapings was performed. At baseline, seroprevalence of HPV 6, 11, 16, 18 and 45 was 53.3, 21.5, 34.9, 21.5 and 9.0 %, respectively. Seropositivity for low-risk HPV (LR-HPV) was associated significantly with age at onset of sexual activity (P=0.001), number of sexual partners until age 20 (P=0.018), lifetime number of sexual partners (P=0.0001), history of genital warts (P=0.0001) and being seropositive for high-risk (HR) HPV (P=0.0001). The same covariates also predicted seropositivity for HR-HPV. During follow-up, 26.7, 13.9, 17.0, 16.8 and 6.6 % of the women seroconverted to L1 antigen of HPV 6, 11, 16, 18 and 45, respectively, between 18.2 and 23.8 months. Independent predictors of seroconversion to LR-HPV were unemployment (P=0.019) and absence of anal sex practice (P=0.031), and to HR-HPV, absence of smoking history and lifetime number of sexual partners. Decay of HPV 6, 11, 16, 18 and 45 antibodies was observed in 2.3, 4.0, 5.3, 4.5 and 1.5 % of the women, respectively, with decay time varying from 27.2 to 35.8 months. These data imply that (i) a substantial proportion of young women are seropositive for both LR- and HR-HPV types, (ii) they frequently undergo seroconversion within 18–24 months, predicted by common covariates, and (iii) antibody decay over 3 years is rare.
Molecular characterization of human rhinovirus field strains isolated during surveillance of enteroviruses
Authors: Blomqvist Soile , Savolainen-Kopra Carita , Paananen Anja , Hovi Tapani , Roivainen Merja
Published: May 2009

Human rhinoviruses (HRVs), which are the most frequent causative agents of acute upper respiratory tract infections, are abundant worldwide. We have identified HRV strains in environmental specimens collected in Finland, Latvia and Slovakia during the surveillance of polio- and other enteroviruses. These acid-sensitive HRV strains were isolated under conditions optimized for growth of most of the enteroviruses, i.e. in stationary human rhabdomyosarcoma cells incubated at 36 °C. Phylogenetic analysis of the sequences derived from the partial 5′ non-coding region and the capsid region coding for proteins VP4/VP2 and VP1 showed that the HRV field strains clustered together with prototype strains of the HRV minor receptor group. Partial sequences of the 3D polymerase coding region generally followed this pattern, with the exception of a set of three HRV field strains that formed a subcluster not close to any of the established HRV-A types, suggesting that recombination may have occurred during evolution of these HRV strains. Phylogenetic analysis of the VP4/VP2 capsid protein coding region showed that the ‘environmental’ HRV field strains were practically identical to HRV strains recently sequenced by others in Australia, the United States and Japan. Analysis of amino acids corresponding to the intercellular adhesion molecule-1 receptor footprint in major receptor group HRVs and also in the low-density lipoprotein receptor footprint of minor receptor group HRVs showed conservation of the ‘minor receptor group-like’ amino acids, indicating that the field strains may have maintained their minor receptor group specificity.
Viral ubiquitin ligase WSSV222 is required for efficient white spot syndrome virus replication in shrimp
Authors: He Fang , Syed Syed Musthaq , Hameed A. S. Sahul , Kwang Jimmy
Published: May 2009

The E3 ligase WSSV222 of white spot syndrome virus (WSSV) is involved in anti-apoptosis regulation by ubiquitin-mediated degradation of tumour suppressor-like protein (TSL), a shrimp tumour suppressor. In the present study, WSSV222 gene expression was silenced by using specific small interfering RNA (siRNA) in Sf9 and BHK cells. Based on the results of the in vitro silencing, WSSV-challenged shrimp were treated with anti-WSSV222 siRNA to knock down WSSV222 protein expression. The survival rate of shrimp and the efficiency of WSSV replication were assessed to evaluate the efficacy of anti-WSSV222 siRNA in regulating WSSV infection in shrimp. The anti-WSSV222 siRNA reduced the cumulative mortality in shrimp challenged with 103 copies of WSSV and delayed the mean time to death in shrimp challenged with the higher dose of 106 copies. The results of real-time quantitative PCR showed that virus replication was delayed and reduced in WSSV-challenged shrimp treated with anti-WSSV222 siRNA in comparison with challenged shrimp treated with random-control siRNA. Co-immunoprecipitation assays revealed that WSSV222 silencing inhibited the degradation of TSL in WSSV-challenged shrimp, indicating the requirement for WSSV222 for efficient replication of WSSV in shrimp.
Autographa californica multiple nucleopolyhedrovirus ORF 23 null mutant produces occlusion-derived virions with fewer nucleocapsids
Authors: Yu Ian-Ling , Bray Doug , Lin Ying-Chu , Lung Oliver
Published: May 2009

Two envelope fusion protein gene homologues have been identified in the baculovirusAutographa californicamultiple nucleopolyhedrovirus (AcMNPV). AcMNPV GP64 protein is fusogenic and essential for propagation and pathogenicity. The F homologue (Ac23) is not essential, is fusion-incompetent in standard assays, but contributes to faster host death. Here, we show that occlusion bodies (OBs) fromAc23null mutants and control viruses do not differ significantly in size and the number of occlusion-derived virions (ODVs) contained; however,Ac23null OBs had a much higher percentage of ODVs with a single nucleocapsid (44.6 %) than the near-isogenic control (11.3 %). Infection of Sf9 cells with Ac23–green fluorescent protein (gfp)-expressing recombinant viruses showed Ac23–gfp fluorescence overlapping perinuclear DAPI staining at later times, a pattern not observed with GP64. These results suggest that F proteins have evolved functions beyond envelope fusion and play a different role from that of GP64 in viruses that contain both proteins.
Influenza A virus proteins PB1 and NS1 are subject to functionally important phosphorylation by protein kinase C
Authors: Mahmoudian Shohreh , Auerochs Sabrina , Gröne Monika , Marschall Manfred
Published: May 2009

The virulence of influenza A viruses depends on the activity of the viral RNA polymerase complex and viral regulatory phosphoproteins. We identified that the protein kinase C (PKC) inhibitor Gö6976 had a post-entry anti-influenza viral effect, by using a polymerase activity-based reporter assay. This inhibitory effect was observed for influenza virus-infected cells as well as for cells transiently transfected with constructs for the RNA polymerase complex. Importantly, thein vitroanalysis of viral protein phosphorylation identified PKCαas a kinase phosphorylating PB1 and NS1, but not PB2, PA or NP. Gö6976 was able to block PKC-specific phosphorylationin vitro. Thus, our data suggest that PKC contributes to the phosphorylation of influenza PB1 and NS1 proteins which appears to be functionally relevant for both viral RNA polymerase activity and efficient viral replication.
ORF3 protein of hepatitis E virus interacts with the Bβ chain of fibrinogen resulting in decreased fibrinogen secretion from HuH-7 cells
Authors: Ratra Ruchi , Kar-Roy Anindita , Lal Sunil K.
Published: May 2009

The ORF3 protein of hepatitis E virus (HEV), the precise cellular functions of which remain obscure, was used in a yeast two-hybrid screen to identify its cellular binding partners. One of the identified interacting partners was fibrinogen Bβprotein. The ORF3–fibrinogen Bβinteraction was verified by co-immunoprecipitation and fluorescence resonance energy transfer in mammalian cells. Fibrinogen is a hepatic acute-phase protein and serves as a central molecule that maintains host homeostasis and haemostasis during an acute-phase response. Metabolic labelling of ORF3-transfected HuH-7 cells showed that secreted as well as intracellular levels of fibrinogen were decreased in these cells compared with vector-transfected controls. Northern hybridization and RT-PCR analyses revealed that the mRNA levels of all three chains of fibrinogen, Aα, Bβandγ, were transcriptionally downregulated in ORF3-transfected cells. The constitutive expression of fibrinogen genes can be significantly upregulated by interleukin (IL)-6, an important mediator of liver-specific gene expression during an acute-phase response. Transcription of fibrinogen genes after IL-6 stimulation was less in ORF3-expressing cells compared with controls. This report adds one more biological function to, and advances our understanding of, the cellular role of the ORF3 protein of HEV. The possible implications of these findings in the virus life cycle are discussed.
Orf virus-encoded chemokine-binding protein is a potent inhibitor of inflammatory monocyte recruitment in a mouse skin model
Authors: Lateef Zabeen , Baird Margaret A. , Wise Lyn M. , Mercer Andrew A. , Fleming Stephen B.
Published: May 2009

The parapoxvirus orf virus causes pustular dermatitis in sheep and is transmissible to humans. The virus encodes a secreted chemokine-binding protein (CBP). We examined the ability of this protein to inhibit migration of murine monocytes in response to CC inflammatory chemokines, using chemotaxis assays, and its effects on monocyte recruitment into the skin, using a mouse model in which inflammation was induced with bacterial lipopolysaccharide. CBP was shown to bind murine chemokines CCL2, CCL3 and CCL5 with high affinity by surface plasmon resonance and it completely inhibited chemokine-induced migration of monocytes at a CBP : chemokine molar ratio of 4 : 1. In the mouse, low levels of CBP potently inhibited the recruitment of Gr-1+/CD11b+monocytes to the site of inflammation in the skin but had little effect on neutrophil recruitment, suggesting that this factor plays a role in disrupting chemokine-induced recruitment of specific immune cell types to infection sites.
Role of anti-lipopolysaccharide factor from the black tiger shrimp, Penaeus monodon, in protection from white spot syndrome virus infection
Authors: Tharntada Sirinit , Ponprateep Sirikwan , Somboonwiwat Kunlaya , Liu Haipeng , Söderhäll Irene , Söderhäll Kenneth , Tassanakajon Anchalee
Published: May 2009

The anti-lipopolysaccharide factor (ALF) from the black tiger shrimp,Penaeus monodon, has been shown previously to exhibit a broad spectrum of activity against various strains of bacteria and fungi. Herein, the recombinant ALFPm3 (rALFPm3) protein was examined for its role in the defence against white spot syndrome virus (WSSV) infection in haematopoietic (Hpt) cell cultures of the freshwater crayfish,Pacifastacus leniusculus, as well as in liveP. monodonshrimps. Incubation of Hpt cell cultures with a mixture of WSSV and rALFPm3 resulted in a dose-dependent decrease in VP28 gene expression levels, compared with those incubated with WSSV alone, with an rALFPm3 IC50value lower than 2.5 μM. However, pre-treatment of Hpt cells with 5 μM rALFPm3 showed no induced protection against subsequent WSSV infection, whereas the synthetic crayfish ALF peptide could protect cells at a higher concentration (10 μM). Thein vivorole of ALFPm3 was examined by injection ofP. monodonwith WSSV pre-treated with rALFPm3 protein. The results clearly showed that rALFPm3 was able to reduce WSSV propagation and prolong the survival of shrimps.
Fusion protein is the main determinant of metapneumovirus host tropism
Authors: de Graaf Miranda , Schrauwen Eefje J. A. , Herfst Sander , van Amerongen Geert , Osterhaus Albert D. M. E. , Fouchier Ron A. M.
Published: May 2009

Human metapneumovirus (HMPV) and avian metapneumovirus subgroup C (AMPV-C) infect humans and birds, respectively. This study confirmed the difference in host range in turkey poults, and analysed the contribution of the individual metapneumovirus genes to host range in an in vitro cell-culture model. Mammalian Vero-118 cells supported replication of both HMPV and AMPV-C in contrast to avian quail fibroblast (QT6) cells in which only AMPV-C replicated to high titres. Inoculation of Vero-118 and QT6 cells with recombinant HMPV in which genes were exchanged with those of AMPV-C revealed that the metapneumovirus fusion (F) protein is the main determinant for host tropism. Chimeric viruses in which polymerase complex proteins were exchanged between HMPV and AMPV-C replicated less efficiently compared with HMPV in QT6 cells. Using mini-genome systems, it was shown that exchanging these polymerase proteins resulted in reduced replication and transcription efficiency in QT6 cells. Examination of infected Vero-118 and QT6 cells revealed that viruses containing the F protein of AMPV-C yielded larger syncytia compared with viruses containing the HMPV F protein. Cell-content mixing assays revealed that the F protein of AMPV-C was more fusogenic compared with the F protein of HMPV, and that the F2 region is responsible for the difference observed between AMPV-C and HMPV F-promoted fusion in QT6 and Vero-118 cells. This study provides insight into the determinants of host tropism and membrane fusion of metapneumoviruses.
Murid herpesvirus-4 lacking thymidine kinase reveals route-dependent requirements for host colonization
Authors: Gill Michael B. , Wright Debbie E. , Smith Christopher M. , May Janet S. , Stevenson Philip G.
Published: May 2009

Gammaherpesviruses infect at least 90 % of the world's population. Infection control is difficult, in part because some fundamental features of host colonization remain unknown, for example whether normal latency establishment requires viral lytic functions. Since human gammaherpesviruses have narrow species tropisms, answering such questions requires animal models. Murid herpesvirus-4 (MuHV-4) provides one of the most tractable. MuHV-4 genomes delivered to the lung or peritoneum persist without lytic replication. However, they fail to disseminate systemically, suggesting that the outcome is inoculation route-dependent. After upper respiratory tract inoculation, MuHV-4 infects mice without involving the lungs or peritoneum. We examined whether host entry by this less invasive route requires the viral thymidine kinase (TK), a gene classically essential for lytic replication in terminally differentiated cells. MuHV-4 TK knockouts delivered to the lung or peritoneum were attenuated but still reached lymphoid tissue. In contrast, TK knockouts delivered to the upper respiratory tract largely failed to establish a detectable infection. Therefore TK, and by implication lytic replication, is required for MuHV-4 to establish a significant infection by a non-invasive route.
La protein binds the predicted loop structures in the 3′ non-coding region of Japanese encephalitis virus genome: role in virus replication
Authors: Vashist Surender , Anantpadma Manu , Sharma Himani , Vrati Sudhanshu
Published: May 2009

Japanese encephalitis virus (JEV) genome is a single-stranded, positive-sense RNA with non-coding regions (NCRs) of 95 and 585 bases at its 5′ and 3′ ends, respectively. These may bind to viral or host proteins important for viral replication. It has been shown previously that three proteins of 32, 35 and 50 kDa bind the 3′ stem–loop (SL) structure of the JEV 3′ NCR, and one of these was identified as 36 kDa Mov34 protein. Using electrophoretic mobility-shift and UV cross-linking assays, as well as a yeast three-hybrid system, it was shown here that La protein binds to the 3′ SL of JEV. The binding was stable under high-salt conditions (300 mM KCl) and the affinity of the RNA–protein interaction was high; the dissociation constant (Kd) for binding of La protein to the 3′ SL was 12 nM, indicating that this RNA–protein interaction is physiologically plausible. Only the N-terminal half of La protein containing RNA recognition motifs 1 and 2 interacted with JEV RNA. An RNA toe-printing assay followed by deletion mutagenesis showed that La protein bound to predicted loop structures in the 3′ SL RNA. Furthermore, it was shown that small interfering RNA-mediated downregulation of La protein resulted in repression of JEV replication in cultured cells.
Reconstitution of initial steps of dsDNA break repair by the RecF pathway of E. coli
Authors: Handa Naofumi , Morimatsu Katsumi , Lovett Susan T. , Kowalczykowski Stephen C.
Published: May 2009

The RecF pathway of Escherichia coli is important for recombinational repair of DNA breaks and gaps. Here `we reconstitute in vitro a seven-protein reaction that recapitulates early steps of dsDNA break repair using purified RecA, RecF, RecO, RecR, RecQ, RecJ, and SSB proteins, components of the RecF system. Their combined action results in processing of linear dsDNA and its homologous pairing with supercoiled DNA. RecA, RecO, RecR, and RecJ are essential for joint molecule formation, whereas SSB and RecF are stimulatory. This reconstituted system reveals an unexpected essential function for RecJ exonuclease: the capability to resect duplex DNA. RecQ helicase stimulates this processing, but also disrupts joint molecules. RecO and RecR have two indispensable functions: They mediate exchange of RecA for SSB to form the RecA nucleoprotein filament, and act with RecF to load RecA onto the SSB–ssDNA complex at processed ssDNA–dsDNA junctions. The RecF pathway has many parallels with recombinational repair in eukaryotes.
Tumorigenicity of cortical astrocyte cell line induced by the protease ADAM17
Authors: Katakowski Mark , Jiang Feng , Zheng XuGuang , Gutierrez Jorge A. , Szalad Alexandra , Chopp Michael
Published: May 2009

The metalloprotease ADAM17 (a.k.a. TACE) plays a pivotal role in the cleavage and activation of membrane‐anchored receptor ligands. More recently, it has been revealed that ADAM17 is a potent sheddase of the epidermal growth factor (EGF) family of ligands and regulates epidermal growth factor receptor (EGFR) activity in a variety of tumors. EGFR is a key component of autonomous growth signaling in several tumors, and correlates with the malignancy grade of astrocytoma. In this study, we tested the hypothesis that over‐expression of ADAM17 in cortical astrocytes derived from normal brain would induce a progression towards a malignant phenotype. Over‐expression of human ADAM17 (hADAM17) in the CTX‐TNA2 cortical astrocyte cell line resulted in non‐adherent growth, increased proliferation, invasiveness, production of angiogenic factors, and expression of genes associated with immature and/or neoplastic cells. hADAM17 up‐regulated EGFR and AKT phosphorylation, and increased proliferation and cell invasion were significantly dependent upon EGFR activity. When implanted in the nude mouse brain, CTX‐TNA2 cells induced low histological grade, benign intraventricular gliomas. In contrast, the same astrocytes with hADAM17 formed large malignant gliomas. Taken together, these findings suggest that unregulated ADAM17 activity induces functional changes in astrocytes that significantly advance the malignant phenotype. (Cancer Sci 2009; 100: 1597–1604)