Termination of signaling by protease-activated receptor-1 is linked to lysosomal sorting

The irreversible proteolytic mechanism by which protease-activated receptor-1 (PAR1), the G protein-coupled receptor (GPCR) for thrombin, is activated raises the question of how it is shut off. Like classic GPCRs, activated PAR1 is rapidly phosphorylated and internalized, but unlike classic GPCRs, which recycle, internalized PAR1 is sorted to lysosomes. A chimeric PAR1 bearing the substance P receptor’s cytoplasmic carboxyl tail sequestered and recycled like wild-type substance P receptor. In cells expressing this chimera, signaling in response to the PAR1-activating peptide SFLLRN ceased as expected upon removal of this agonist. Strikingly, however, when the chimera was activated proteolytically by thrombin, signaling persisted even after thrombin was removed. This persistent signaling was apparently due to “resignaling” by previously activated receptors that had internalized and recycled back to the cell surface. Thus the cytoplasmic carboxyl tail of PAR1 specifies an intracellular sorting pattern that is linked to its signaling properties. In striking contrast to most GPCRs, sorting of activated PAR1 to lysosomes rather than recycling is critical for terminating PAR1 signaling—a trafficking solution to a signaling problem.

Systemic spread of an RNA insect virus in plants expressing plant viral movement protein genes

Flock house virus (FHV), a single-stranded RNA insect virus, has previously been reported to cross the kingdom barrier and replicate in barley protoplasts and in inoculated leaves of several plant species [Selling, B. H., Allison, R. F. & Kaesberg, P. (1990) Proc. Natl. Acad. Sci. USA 87, 434–438]. There was no systemic movement of FHV in plants. We tested the ability of movement proteins (MPs) of plant viruses to provide movement functions and cause systemic spread of FHV in plants. We compared the growth of FHV in leaves of nontransgenic and transgenic plants expressing the MP of tobacco mosaic virus or red clover necrotic mosaic virus (RCNMV). Both MPs mobilized cell-to-cell and systemic movement of FHV in Nicotiana benthamiana plants. The yield of FHV was more than 100-fold higher in the inoculated leaves of transgenic plants than in the inoculated leaves of nontransgenic plants. In addition, FHV accumulated in the noninoculated upper leaves of both MP-transgenic plants. RCNMV MP was more efficient in mobilizing FHV to noninoculated upper leaves. We also report here that FHV replicates in inoculated leaves of six additional plant species: alfalfa, Arabidopsis, Brassica, cucumber, maize, and rice. Our results demonstrate that plant viral MPs cause cell-to-cell and long-distance movement of an animal virus in plants and offer approaches to the study of the evolution of viruses and mechanisms governing mRNA trafficking in plants as well as to the development of promising vectors for transient expression of foreign genes in plants.

Biomechanics of the movable pretarsal adhesive organ in ants and bees

Hymenoptera attach to smooth surfaces with a flexible pad, the arolium, between the claws. Here we investigate its movement in Asian weaver ants (Oecophylla smaragdina) and honeybees (Apis mellifera).  When ants run upside down on a smooth surface, the arolium is unfolded and folded back with each step. Its extension is strictly coupled with the retraction of the claws. Experimental pull on the claw-flexor tendon revealed that the claw-flexor muscle not only retracts the claws, but also moves the arolium. The elicited arolium movement comprises (i) about a 90° rotation (extension) mediated by the interaction of the two rigid pretarsal sclerites arcus and manubrium and (ii) a lateral expansion and increase in volume. In severed legs of O. smaragdina ants, an increase in hemolymph pressure of 15 kPa was sufficient to inflate the arolium to its full size. Apart from being actively extended, an arolium in contact also can unfold passively when the leg is subject to a pull toward the body.  We propose a combined mechanical–hydraulic model for arolium movement: (i) the arolium is engaged by the action of the unguitractor, which mechanically extends the arolium; (ii) compression of the arolium gland reservoir pumps liquid into the arolium; (iii) arolia partly in contact with the surface are unfolded passively when the legs are pulled toward the body; and (iv) the arolium deflates and moves back to its default position by elastic recoil of the cuticle.

Responses of the phototransduction cascade to dim light.

The biochemistry of visual excitation is kinetically explored by measuring the activity of the cGMP phosphodiesterase (PDE) at light levels that activate only a few tens of rhodopsin molecules per rod. At 23 degrees C and in the presence of ATP, the pulse of PDE activity lasts 4 s (full width at half maximum). Complementing the rod outer segments (ROS) with rhodopsin kinase (RK) and arrestin or its splice variant p44 does not significantly shorten the pulse. But when the ROS are washed, the duration of the signal doubles. Adding either arrestin or p44 back to washed ROS approximately restores the pulse width to its initial value, with p44 being 10 times more efficient than arrestin. This supports the idea that, in vivo, capping of phosphorylated R* is mostly done by p44. When myristoylated (14:0) recoverin is added to unwashed ROS, the pulse duration and amplitude increase by about 50% if the free calcium is 500 nM. This effect increases further if the calcium is raised to 1 microM. Whenever R* deactivation is changed--when RK is exogenously enriched or when ATP is omitted from the buffer--there is no impact on the rising slope of the PDE pulse but only on its amplitude and duration. We explain this effect as due to the unequal competition between transducin and RK for R*. The kinetic model issued from this idea fits the data well, and its prediction that enrichment with transducin should lengthen the PDE pulse is successfully validated.

Interleukin 2 induces CD8+ T cell-mediated suppression of human immunodeficiency virus replication in CD4+ T cells and this effect overrides its ability to stimulate virus expression.

The nonlytic suppression of human immunodeficiency virus (HIV) production from infected CD4+ T cells by CD8+ lymphocytes from HIV-infected individuals is one of the most potent host-mediated antiviral activities observed in vitro. We demonstrate that the pleiotropic cytokine interleukin 2 (IL-2), but not IL-12, is a potent inducer of the CD8+ HIV suppressor phenomenon. IL-2 induces HIV expression in peripheral blood or lymph node mononuclear cells from HIV-infected individuals in the absence of CD8+ T cells. However, IL-2 induces CD8+ T cells to suppress HIV expression when added back to these cultures, and this effect dramatically supersedes the ability to IL-2 to induce HIV expression. Five to 25 times fewer CD8+ cells were required to obtain comparable levels of inhibition of viral production if they were activated in the presence of IL-2 as compared with IL-12 or no exogenous cytokine. Furthermore, IL-2 appeared either to induce a qualitative increase in HIV suppressor cell activity or to increase the relative frequency of suppressor cells in the activated (CD25+) CD8+ populations. Analyses of proviral levels in peripheral blood mononuclear cells suggest that CD8+ T cell-mediated lysis of in vivo infected cells is not induced by IL-2. These results have implications for our understanding of the effects of impaired IL-2 production during HIV disease as well as the overall effects of IL-2-based immunotherapy on HIV replication in vivo.

Shigella flexneri surface protein IcsA is sufficient to direct actin-based motility.

Shigella flexneri is a Gram-negative bacterial pathogen that can grow directly in the cytoplasm of infected host cells and uses a form of actin-based motility for intra- and intercellular spread. Moving intracellular bacteria are associated with a polarized "comet tail" composed of actin filaments. IcsA, a 120-kDa outer membrane protein necessary for actin-based motility, is located at a single pole on the surface of the organism, at the junction with the actin tail. Here, we demonstrate that stable expression of IcsA on the surface of Escherichia coli is sufficient to allow actin-dependent movement of E. coli in cytoplasmic extracts, at rates comparable to the movement of S. flexneri in infected cells. Thus, IcsA is the sole Shigella-specific factor required for actin-based motility. Continuous protein synthesis and polarized distribution of the protein are not necessary for actin tail formation or movement. Listeria monocytogenes is an unrelated bacterial pathogen that exhibits similar actin-based intracytoplasmic motility. Actin filament dynamics in the comet tails associated with the two different organisms are essentially identical, which indicates that they have independently evolved mechanisms to interact with the same components of the host cytoskeleton.

Letter from the Navy Department to James O. Creighton,

One letter with instructions to give convoy to the vessel that would bring Tudor back to the United States.

Letters from Z.W. Nixon to William Tudor,

Four letters regarding the legal and financial aspects involving the Chanca silver mine and its stakeholders, Tudor, McCall, Maling, and Prevost, and a copy of a letter from Nixon to Prevost. Nixon additionally comments on domestic news, including the renaming of the U.S.S. Susquehanna as the U.S.S. Brandywine by John Quincy Adams in honor of the Marquis de Lafayette. The ship conveyed Lafayette back to France after his tour of the United States. Nixon also mentions Charles Stewart and his court martial.

Letter from Henry Waddington, Jr., to William Tudor,

One letter requesting assistance with sending a sick American citizen back to the United States.

Letter from Samuel Willard, Harvard College, Cambridge, Massachusetts, to William Willard, Petersham, Massachusetts, February 28, 1802

Willard describes his trip back to Harvard from Petersham, reports that President Willard and family were doing well, although “he has had an ill turn since, but has recovered,” and concludes the letter by asking for more money.

Liberalising trade in services: creating new migration opportunities? Research Paper in Law, 1/2010

Introduction. It is quite uncommon to associate migration with the rules on services trade. Indeed, all economic definitions of services insist on their immaterial nature and on the increased possibility of trading them ‘virtually’ over networks or else, without any physical movement of the parties involved. Somehow this ‘immaterial’ nature of services reflects on their providers/recipients which seem to be ‘invisible’. Even though most services still require the physical contact of the provider with the recipient1 and, when provided over national borders, do entail migration, service providers and/or recipients are rarely thought of as ‘immigrants’. This may be due to the fact that they enter the foreign territory with a specific aim and, once this aim accomplished, move back to their state of origin; technically they only qualify as short term non-cyclical migrants and are of little interest to policy-makers. A second reason may be that both service providers and recipients are economically desirable: the former are typically highly skilled and trained professionals and the latter are well-off ‘visitors’, increasing consumption in the host state. The legal definition of services in Article 57 TFEU (ex Art. 50 EC) further nourishes this idea about service providers/recipients not being migrants: the relevant Treaty rules only apply when the provisions on free movement of workers and freedom of establishment – themselves clearly linked to migration – do not apply. This distinction has been fleshed up by the ECJ which has consistently held that the distinction between the rules on establishment, on the one hand, and the rules on services, on the other, lies on duration.2 Indeed, all EC manuals state four types of service provision falling under the EC Treaty: a) where the service provider moves to the recipient’s state, for a short period of time (longer stay would amount to establishment), b) where the service recipients themselves move to the state where the service is offered (eg for medical care, education, tourism etc), c) where both service providers and recipients move together in another member state (eg a tourist guide accompanying a group travelling abroad) and d) where the service itself is provided across the borders (typically through the use of ICTs). None of these situations would typically qualify as migration. The above ‘dissociation’ between services and migration has been gradually weakened in the recent years. Indeed, migration is increasingly connected to the transnational provision of services. This is the result of three kinds of factors: developments in the European Court of Justice’s (ECJ) case law; legislative initiatives in the EU; and the GATS. Each one of these is considered in some detail below. The aim of the analysis which follows is to show the extent to which (legislative and judicial) policies aimed at the free provision of services actively affect migration conditions within the EU. The EC rules on the provision of services primarily affect the movement of EU nationals. As it will be shown below, however, third country nationals (TCNs) may also claim the benefits of the rules on services, either as recipients thereof or as employees of some EC undertaking which is providing services in another member state (posted workers).

What role for migration policy in the Ukraine crisis? CEPS Commentaries, 27 March 2014

While the geopolitics of the Ukraine crisis have dominated headlines, little attention has been paid to the potential challenges arising from the movement of people from the region to the EU. Yet recent history should tell us this could be a grave oversight. As we witnessed during the Arab Spring in 2011, political upheaval can result in people fleeing their state in fear of persecution or seeking to leave their state in search of new horizons and economic opportunities. The EU would do well to learn from that experience and the policy failures that resulted from the Union’s response of closing its borders and returning people to Africa. This Commentary argues that it is critical that – independently of the still uncertain outcome of the Ukraine crisis – the EU formulates and implements a credible policy strategy addressing the potential impact and benefits of mobility between Ukraine and the EU.

British Balance of Competence Reviews, Part III: More reform than renegotiation or repatriation. EPIN [Working] Paper No. 42/December 2014. [see Abstract for I and II]

This paper, the third in a series for a CEPS project on the ‘The British Question’, is pegged on an ambitious exercise by the British government to review all the competences of the European Union on the basis of evidence submitted by independent stakeholders. The reviews considered in this paper cover the following EU policies: the single market for services, financial markets, the free movement of people, cohesion, energy, agriculture, fisheries, competition, social and employment policies, and fundamental rights. The declared objective of Prime Minister Cameron is to secure a ‘new settlement’ between the UK and the EU. From political speeches in the UK one can identify three different types of possible demand: reform of EU policies, renegotiation of the UK’s specific terms of membership, and repatriation of competences from the EU back to the member states. As most of the reviews are now complete, three points are becoming increasingly clear: i) The reform agenda – past, present or future - concerns virtually every branch of EU policy, including several cases reviewed here that are central to stated UK economic interests. The argument that the EU is ‘unreformable’ is shown to be a myth. ii) The highly sensitive cases of immigration from the EU and social policies may translate into requests for renegotiation of specific conditions for the UK, but further large-scale opt-outs, as in the case of the euro and justice and home affairs, are implausible. iii) While demands for repatriation of EU competences are voiced in general terms in public debate in the UK, no specific proposals emerge from the evidence as regards competences at the level at which they are identified in the treaties, and there is no chance of achieving consensus for such ideas among member states. Michael Emerson and Steven Blockmans, “British Balance of Competence Reviews, Part I: ‘Competences about right, so far’”, CEPS/EPIN Working Paper No. 35, October 2013 (www.ceps.eu/book/british-balance-competence-reviews-part-i-%E2%80%98competences-about-right-so-far%E2%80%99)(http://aei.pitt.edu/45599/); Michael Emerson, Steven Blockmans, Steve Peers and Michael Wriglesworth, “British Balance of Competence Reviews, Part II: Again, a huge contradiction between the evidence and Eurosceptic populism”, CEPS/EPIN Working Paper No. 40, June 2014 (www.ceps.eu/book/british-balance-competence-reviews-part-ii-again-huge-contradiction-between-evidence-and-eurosc)(http://aei.pitt.edu/52452/).

Explaining and Comparing - Improving United States and European Union-Africa Economic Relations: Policy Memo. ACES Working Papers, 2012

As evidenced by the disparities seen in the world, development does not occur uniformly around the world. Global superpowers like the United States and the European Union collectively dominate other parts of the world simply because of their ability to develop at a faster rate. With the rise of globalization and the increasing connectivity of the world economy, the world has reached a time where it is imperative that those nations and unions holding power to commit to elevating their fellow nations through supportive policy ties. The United States and the European Union, as leading global nations, have an important role in developing the economies of other countries; by taking various policy measures, the US and EU can create stronger economic ties to Africa and create a advantageous relationship for all the regions involved.

The European Union Multiannual Financial Framework 2014-2020: How to do more for less? IES Policy Brief Issue 2013/05 • May 2013

The European Council meeting on 7 and 8 February 2013 attracted an unusual level of attention from media and citizens. For a couple of days, Europe played a more important role in national politics and news. Sensation-frenzied media and excited politicians spouted notions of ‘a battle’, ‘winners’, ‘losers’ or ‘striking deals’, as if Europe had gone back to the time when its military powers still conflicted. After more than 24 hours of intense negotiations, the respective Member States leaders left Brussels with ‘good news’ for their citizens. However, those with more Euro-federalist feelings were left with a sense of non-accomplishment and missed opportunities, not only because the EU budget for the first time in history was set for a net decrease, but also because the European Council’s conclusions did not contain any ground-breaking changes to this system. Nevertheless, the European Parliament (EP) immediately reminded Europe about its role and outlined its conditions for further negotiations. Thus, the supporters of a modern and stronger EU budget still see a chance in the consent procedure and hope to shift the focus of the debate from the juste retour spirit to the consideration of the European common good. Is there still a chance for such a shift? What issues are at stake?