An essential regulatory role for macrophage migration inhibitory factor in T-cell activation.

The protein known as macrophage migration inhibitory factor (MIF) was one of the first cytokines to be discovered and was described 30 years ago to be a T-cell-derived factor that inhibited the random migration of macrophages in vitro. A much broader role for MIF has emerged recently as a result of studies that have demonstrated it to be released from the anterior pituitary gland in vivo. MIF also is the first protein that has been identified to be secreted from monocytes/macrophages upon glucocorticoid stimulation. Once released, MIF acts to "override" or counter-regulate the suppressive effects of glucocorticoids on macrophage cytokine production. We report herein that MIF plays an important regulatory role in the activation of T cells induced by mitogenic or antigenic stimuli. Activated T cells produce MIF and neutralizing anti-MIF antibodies inhibit T-cell proliferation and interleukin 2 production in vitro, and suppress antigen-driven T-cell activation and antibody production in vivo. T cells also release MIF in response to glucocorticoid stimulation and MIF acts to override glucocorticoid inhibition of T-cell proliferation and interleukin 2 and interferon gamma production. These studies indicate that MIF acts in concert with glucocorticoids to control T-cell activation and assign a previously unsuspected but critical role for MIF in antigen-specific immune responses.

Pax3 modulates expression of the c-Met receptor during limb muscle development.

Pax3 is a transcription factor whose expression has been used as a marker of myogenic precursor cells arising in the lateral somite destined to migrate to and populate the limb musculature. Accruing evidence indicates that the embryologic origins of axial and appendicular muscles are distinct, and limb muscle abnormalities in both mice and humans harboring Pax3 mutations support this distinction. The mechanisms by which Pax3 affects limb muscle development are unknown. The tyrosine kinase receptor for hepatocyte growth factor/scatter factor encoded by the c-met protooncogene is also expressed in limb muscle progenitors and, like Pax-3, is required in the mouse for limb muscle development. Here, we show that c-met expression is markedly reduced in the lateral dermomyotome of Splotch embryos lacking Pax3. We show that Pax3 can stimulate c-met expression in cultured cells, and we identify a potential Pax3 binding site in the human c-MET promoter that may contribute to direct transcriptional regulation. In addition, we have found that several cell lines derived from patients with rhabdomyosarcomas caused by a t(2;13) chromosomal translocation activating PAX3 express c-MET, whereas those rhabdomyosarcoma cell lines examined without the translocation do not. These results are consistent with a model in which Pax3 modulates c-met expression in the lateral dermomyotome, a function that is required for the appropriate migration of these myogenic precursors to the limb where the ligand for c-met (hepatocyte growth factor/scatter factor) is expressed at high levels.

Intraembryonic hematopoietic cell migration during vertebrate development.

Vertebrate hematopoietic stem cells are derived from vental mesoderm, which is postulated to migrate to both extra- and intraembryonic positions during gastrula and neurula stages. Extraembryonic migration has previously been documented, but the origin and migration of intraembryonic hematopoietic cells have not been visualized. The zebrafish and most other teleosts do not form yolk sac blood islands during early embryogenesis, but instead hematopoiesis occurs solely in a dorsal location known as the intermediate cell mass (IM) or Oellacher. In this report, we have isolated cDNAs encoding zebrafish homologs of the hematopoietic transcription factors GATA-1 and GATA-2 and have used these markers to determine that the IM is formed from mesodermal cells in a posterior-lateral position on the yolk syncytial layer of the gastrula yolk sac. Surprisingly, cells of the IM then migrate anteriorly through most of the body length prior to the onset of active circulation and exit onto the yolk sac. These findings support a hypothesis in which the hematopoietic program of vertebrates is established by variations in homologous migration pathways of extra- and intraembryonic progenitors.

Characterization and localization of the cytoplasmic dynein heavy chain in Aspergillus nidulans.

Migration of nuclei throughout the mycelium is essential for the growth and differentiation of filamentous fungi. In Aspergillus nidulans, the nudA gene, which is involved in nuclear migration, encodes a cytoplasmic dynein heavy chain. In this paper we use antibodies to characterize the Aspergillus cytoplasmic dynein heavy chain (ACDHC) and to show that the ACDHC is concentrated at the growing tip of the fungal mycelium. We demonstrate that four temperature-sensitive mutations in the nudA gene result in a striking decrease in ACDHC protein. Cytoplasmic dynein has been implicated in nuclear division in animal cells. Because the temperature-sensitive nudA mutants are able to grow slowly with occasional nuclei found in the mycelium and are able to undergo nuclear division, we have created a deletion/disruption nudA mutation and a tightly downregulated nudA mutation. These mutants exhibit a phenotype very similar to that of the temperature-sensitive nudA mutants with respect to growth, nuclear distribution, and nuclear division. This suggests that there are redundant backup motor proteins for both nuclear migration and nuclear division.

Serotonin regulates mouse cranial neural crest migration.

Serotonergic agents (uptake inhibitors, receptor ligands) cause significant craniofacial malformations in cultured mouse embryos suggesting that 5-hydroxytryptamine (serotonin) (5-HT) may be an important regulator of craniofacial development. To determine whether serotonergic regulation of cell migration might underly some of these effects, cranial neural crest (NC) explants from embryonic day 9 (E9) (plug day = E1) mouse embryos or dissociated mandibular mesenchyme cells (derived from NC) from E12 embryos were placed in a modified Boyden chamber to measure effects of serotonergic agents on cell migration. A dose-dependent effect of 5-HT on the migration of highly motile cranial NC cells was demonstrated, such that low concentrations of 5-HT stimulated migration, whereas this effect was progressively lost as the dose of 5-HT was increased. In contrast, most concentrations of 5-HT inhibited migration of less motile, mandibular mesenchyme cells. To investigate the possible involvement of specific 5-HT receptors in the stimulation of NC migration, several 5-HT subtype-selective antagonists were used to block the effects of the most stimulatory dose of 5-HT (0.01 microM). Only NAN-190 (a 5-HT1A antagonist) inhibited the effect of 5-HT, suggesting involvement of this receptor. Further evidence was obtained by using immunohistochemistry with 5-HT receptor antibodies, which revealed expression of the 5-HT1A receptor but not other subtypes by migrating NC cells in both embryos and cranial NC explants. These results suggest that by activating appropriate receptors 5-HT may regulate migration of cranial NC cells and their mesenchymal derivatives in the mouse embryo.

Genetics and the origin of European languages.

A new set of European genetic data has been analyzed to dissect independent patterns of geographic variation. The most important cause of European genetic variation has been confirmed to correspond to the migration of Neolithic farmers from the area of origin of agriculture in the Middle East. The next most important component of genetic variation is apparently associated with a north-south gradient possibly due to adaptation to cold climates but also to the differentiation of the Uralic and the Indo-European language-speaking people; however, the relevant correlations are not significantly different from zero after elimination of the spatial autocorrelation. The third component is highly correlated with the infiltration of the Yamna ("Kurgan") people, nomadic pastoralists who domesticated the horse and who have been claimed to have spread Indo-European languages to Europe; this association, which is statistically significant even when taking spatial autocorrelations into account, does not completely exclude the hypothesis of Indo-European as the language of Neolithic farmers. It is possible that both expansions were responsible for the spread of different subfamilies of Indo-European languages, but our genetic data cannot resolve their relative importance.

Three-dimensional tracking of motile bacteria near a solid planar surface.

Knowing how motile bacteria move near and along a solid surface is crucial to understanding such diverse phenomena as the migration of infectious bacteria along a catheter, biofilm growth, and the movement of bacteria through the pore spaces of saturated soil, a critical step in the in situ bioremediation of contaminated aquifers. In this study, a tracking microscope is used to record the three-dimensional motion of Escherichia coli near a planar glass surface. Data from the tracking microscope are analyzed to quantify the effects of bacteria-surface interactions on the swimming behavior of bacteria. The speed of cells approaching the surface is found to decrease in agreement with the mathematical model of Ramia et al. [Ramia, M., Tullock, D. L. & Phan-Tien, N. (1993) Biophys J. 65,755-778], which represents the bacteria as spheres with a single polar flagellum rotating at a constant rate. The tendency of cells to swim adjacent to the surface is shown in computer-generated reproductions of cell traces. The attractive interaction potential between the cells and the solid surface is offered as one of several possible explanations for this tendency.

Priming of tumor-specific T cells in the draining lymph nodes after immunization with interleukin 2-secreting tumor cells: three consecutive stages may be required for successful tumor vaccination.

Although both CD4+ and CD8+ T cells are clearly required to generate long-lasting anti-tumor immunity induced by s.c. vaccination with interleukin 2 (IL-2)-transfected, irradiated M-3 clone murine melanoma cells, some controversy continues about the site and mode of T-cell activation in this system. Macrophages, granulocytes, and natural killer cells infiltrate the vaccination site early after injection into either syngeneic euthymic DBA/2 mice or athymic nude mice and eliminate the inoculum within 48 hr. We could not find T cells at the vaccination site, which argues against the concept that T-cell priming by the IL-2-secreting cancer cells occurs directly at that location. However, reverse transcription-PCR revealed transcripts indicative of T-cell activation and expansion in the draining lymph nodes of mice immunized with the IL-2-secreting vaccine but not in mice vaccinated with untransfected, irradiated M-3 cells. We therefore propose that the antigen-presenting cells, which invade the vaccination site, process tumor-derived antigens and, subsequently, initiate priming of tumor-specific T lymphocytes in lymphoid organs. These findings suggest a three-stage process for the generation of effector T cells after vaccination with IL-2-secreting tumor cells: (i) tumor-antigen uptake and processing at the site of injection by antigen-presenting cells, (ii) migration of antigen-presenting cells into the regional draining lymph nodes, where T-cell priming occurs, and (iii) circulation of activated T cells that either perform or initiate effector mechanisms leading to tumor cell destruction.

Oleic acid modulates mRNA expression of liver X receptor (LXR) and its target genes ABCA1 and SREBP1c in human neutrophils

Purpose: Regulation of liver X receptors (LXRs) is essential for cholesterol homeostasis and inflammation. The present study was conducted to determine whether oleic acid (OA) could regulate mRNA expression of LXRα and LXRα-regulated genes and to assess the potential promotion of oxidative stress by OA in neutrophils. Methods: Human neutrophils were treated with OA at different doses and LXR target gene expression, oxidative stress production, lipid efflux and inflammation state were analyzed. Results: We describe that mRNA synthesis of both LXRα and ABCA1 (a reverse cholesterol transporter) was induced by OA in human neutrophils. This fatty acid enhanced the effects of LXR ligands on ABCA1 and LXR expression, but it decreased the mRNA levels of sterol regulatory element-binding protein 1c (a transcription factor that regulates the synthesis of triglycerides). Although OA elicited a slight oxidative stress in the short term (15–30 min) in neutrophils, it is unlikely that this is relevant for the modulation of transcription in our experimental conditions, which involve longer incubation time (i.e., 6 h). Of physiological importance is our finding that OA depresses intracellular lipid levels and that markers of inflammation, such as ERK1/2 and p38 mitogen-activated protein kinase phosphorylation, were decreased by OA treatment. In addition, 200 μM OA reduced the migration of human neutrophils, another marker of the inflammatory state. However, OA did not affect lipid peroxidation induced by pro-oxidant agents. Conclusions: This work presents for the first time evidence that human neutrophils are highly sensitive to OA and provides novel data in support of a protective role of this monounsaturated acid against the activation of neutrophils during inflammation.

Synthesis and Characterization of Lactic Acid Oligomers: Evaluation of Performance as Poly(Lactic Acid) Plasticizers

The use of fully bio-based and biodegradable materials for massive applications, such as food packaging, is an emerging tendency in polymer research. But the formulations proposed in this way should preserve or even increase the functional properties of conventional polymers, such as transparency, homogeneity, mechanical properties and low migration of their components to foodstuff. This is not always trivial, in particular when brittle biopolymers, such as poly(lactic acid) (PLA), are considered. In this work the formulation of innovative materials based on PLA modified with highly compatible plasticizers, i.e. oligomers of lactic acid (OLAs) is proposed. Three different synthesis conditions for OLAs were tested and the resulting additives were further blended with commercial PLA obtaining transparent and ductile materials, able for films manufacturing. These materials were tested in their structural, thermal and tensile properties and the best formulation among the three materials was selected. OLA with molar mass (Mn) around 1,000 Da is proposed as an innovative and fully compatible and biodegradable plasticizer for PLA, able to replace conventional plasticizers (phthalates, adipates or citrates) currently used for films manufacturing in food packaging applications.

3D geometry of growth strata in a fault-propagation fold: insights into space–time evolution of the Crevillente Fault (Abanilla-Alicante sector), Betic Cordillera, Spain

This work presents a 3D geometric model of growth strata cropping out in a fault-propagation fold associated with the Crevillente Fault (Abanilla-Alicante sector) from the Bajo Segura Basin (eastern Betic Cordillera, southern Spain). The analysis of this 3D model enables us to unravel the along-strike and along-section variations of the growth strata, providing constraints to assess the fold development, and hence, the fault kinematic evolution in space and time. We postulate that the observed along-strike dip variations are related to lateral variation in fault displacement. Along-section variations of the progressive unconformity opening angles indicate greater fault slip in the upper Tortonian–Messinian time span; from the Messinian on, quantitative analysis of the unconformity indicate a constant or lower tectonic activity of the Crevillente Fault (Abanilla-Alicante sector); the minor abundance of striated pebbles in the Pliocene-Quaternary units could be interpreted as a decrease in the stress magnitude and consequently in the tectonic activity of the fault. At a regional scale, comparison of the growth successions cropping out in the northern and southern limits of the Bajo Segura Basin points to a southward migration of deformation in the basin. This means that the Bajo Segura Fault became active after the Crevillente Fault (Abanilla-Alicante sector), for which activity on the latter was probably decreasing according to our data. Consequently, we propose that the seismic hazard at the northern limit of the Bajo Segura Basin should be lower than at the southern limit.

Ukrainians' EU migration prospects. OSW Commentary No. 128, 10.03.2014.

The political crisis in Ukraine, particularly the bloodshed seen on 18–20 February and the subsequent Russian intervention in Crimea, has sparked fears of another possible wave of immigrants heading to the EU. However, the country was partially politically stabilised (at least in its central and western parts), and this has made the scenario of a mass migration of people from Ukraine rather unlikely. If there is no civil war in Ukraine, any further development of the political situation in Ukraine may have only an indirect impact on the actual migration. Should the political instability continue, the Ukrainian economy remain in recession while jobs are available for Ukrainian immigrants in the EU, then an increase in the migration of Ukrainian citizens to the EU, including Poland, would be possible. In the short term there may be two characteristic groups of immigrants: (1) young people who will attempt to leave Ukraine for good due to the lack of job opportunities; (2) circulating migrants, mainly from western Ukraine, who will be looking for temporary jobs. Only if the economic downturn trend and political turmoil in Ukraine continues for a longer time, will settlement migration increase.

Does the Common Agricultural Policy Reduce Farm Labour Migration? Panel data analysis across EU regions. Factor Markets Working Paper No. 28, July 2012

This paper deals with the determinants of labour out-migration from agriculture across 149 EU regions over the 1990–2008 period. The central aim is to shed light on the role played by payments from the common agricultural policy (CAP) on this important adjustment process. Using static and dynamic panel data estimators, we show that standard neoclassical drivers, like relative income and the relative labour share, represent significant determinants of the intersectoral migration of agricultural labour. Overall, CAP payments contributed significantly to job creation in agriculture, although the magnitude of the economic effect was rather moderate. We also find that pillar I subsidies exerted an effect approximately two times greater than that of pillar II payments.

The Impact of CAP Payments on the Exodus of Labour from Agriculture in Selected EU Member States. Factor Markets Working Document No. 66, August 2013

This paper examines the determinants of exit from agriculture under the implementation of CAP payments in four selected EU countries (France, Hungary, Italy and Poland) in the period 2005-08. The study employs micro-data from the European Union Labour Force Survey and regional data from the Farm Accountancy Data Network. We differentiate among the different measures of farm payments, looking at the individual impact of Pillar 1 instruments, i.e. coupled and decoupled payments, and at those in Pillar 2, targeted at rural development. The main results suggest that total subsidies at the regional level are negatively associated with the out-farm migration of agricultural workers in the two New member states, Hungary and Poland, so that the CAP would seem to hinder the exit of labour from agriculture. Conversely, the non-significant results for the ‘old’ member states may be interpreted as the result of opposing effects of coupled payments and rural development support. The diverse impact of CAP on the likelihood of leaving agriculture in the four countries reflects the heterogeneity across European member states, due to different market and production structures, which does not allow a common and simple generalisation of the effect of the CAP on labour allocation.

Identification of cyclins A1, E1 and vimentin as downstream targets of heme oxygenase-1 in vascular endothelial growth factor-mediated angiogenesis

Angiogenesis is an essential physiological process and an important factor in disease pathogenesis. However, its exploitation as a clinical target has achieved limited success and novel molecular targets are required. Although heme oxygenase-1 (HO-1) acts downstream of vascular endothelial growth factor (VEGF) to modulate angiogenesis, knowledge of the mechanisms involved remains limited. We set out identify novel HO-1 targets involved in angiogenesis. HO-1 depletion attenuated VEGF-induced human endothelial cell (EC) proliferation and tube formation. The latter response suggested a role for HO-1 in EC migration, and indeed HO-1 siRNA negatively affected directional migration of EC towards VEGF; a phenotype reversed by HO-1 over-expression. EC from Hmox1(-/-) mice behaved similarly. Microarray analysis of HO-1-depleted and control EC exposed to VEGF identified cyclins A1 and E1 as HO-1 targets. Migrating HO-1-deficient EC showed increased p27, reduced cyclin A1 and attenuated cyclin-dependent kinase 2 activity. In vivo, cyclin A1 siRNA inhibited VEGF-driven angiogenesis, a response reversed by Ad-HO-1. Proteomics identified structural protein vimentin as an additional VEGF-HO-1 target. HO-1 depletion inhibited VEGF-induced calpain activity and vimentin cleavage, while vimentin silencing attenuated HO-1-driven proliferation. Thus, vimentin and cyclins A1 and E1 represent VEGF-activated HO-1-dependent targets important for VEGF-driven angiogenesis.