Key role for mast cells in nonatopic asthma

The mechanisms involved in nonatopic asthma are poorly defined. In particular, the importance of mast cells in the development of nonatopic asthma is not clear. In the mouse, pulmonary hypersensitivity reactions induced by skin sensitization with the low-m.w. compound dinitrofluorobenzene (DNFB) followed by an intra-airway application of the hapten have been featured as a model for nonatopic asthma. In present study, we used this model to examine the role of mast cells in the pathogenesis of nonatopic asthma. First, the effect of DNFB sensitization and intra-airway challenge with dinitrobenzene sulfonic acid (DNS) on mast cell activation was monitored during the early phase of the response in BALB/c mice. Second, mast cell-deficient W/W(v) and Sl/Sl(d) mice and their respective normal (+/+) littermate mice and mast cell-reconstituted W/W(v) mice (bone marrow-derived mast cells-->W/W(v)) were used. Early phase mast cell activation was found, which was maximal 30 min after DNS challenge in DNFB-sensitized BALB/c, +/+ mice but not in mast cell-deficient mice. An acute bronchoconstriction and increase in vascular permeability accompanied the early phase mast cell activation. BALB/c, +/+ and bone marrow-derived mast cell-->W/W(v) mice sensitized with DNFB and DNS-challenged exhibited tracheal hyperreactivity 24 and 48 h after the challenge when compared with vehicle-treated mice. Mucosal exudation and infiltration of neutrophils in bronchoalveolar lavage fluid associated the late phase response. Both mast cell-deficient strains failed to show any features of this hypersensitivity response. Our findings show that mast cells play a key role in the regulation of pulmonary hypersensitivity responses in this murine model for nonatopic asthma.     

Megalin in normal tissues and carcinoma cells carries oligo/poly α2,8 deaminoneuraminic acid as a unique posttranslational modification

In rat kidney, megalin, a member of the low density lipoprotein receptor gene family, is the sole glycoprotein which carries oligo/poly 2,8 deaminoneuraminic acid (KDN) as a posttranslational modification. We have investigated immunoprecipitated megalin from rat brain, lung and placenta, mouse yolk sac carcinoma and megalin synthesizing carcinoma cell lines, for presence of this unique glycan structure. Our immunoblot analysis revealed the presence of oligo/poly 2,8 KDN on megalin in all the studied normal tissues and carcinoma cells. Furthermore, it is demonstrated that to be part of oligosaccharides O-glycosidically linked to megalin.     

Hearing sensitivity and amplitude coding in bats are differentially shaped by echolocation calls and social calls

Differences in auditory perception between species are influenced by phylogenetic origin and the perceptual challenges imposed by the natural environment, such as detecting prey- or predator-generated sounds and communication signals. Bats are well suited for comparative studies on auditory perception since they predominantly rely on echolocation to perceive the world, while their social calls and most environmental sounds have low frequencies. We tested if hearing sensitivity and stimulus level coding in bats differ between high and low-frequency ranges by measuring auditory brainstem responses (ABRs) of 86 bats belonging to 11 species. In most species, auditory sensitivity was equally good at both high- and low-frequency ranges, while amplitude was more finely coded for higher frequency ranges. Additionally, we conducted a phylogenetic comparative analysis by combining our ABR data with published data on 27 species. Species-specific peaks in hearing sensitivity correlated with peak frequencies of echolocation calls and pup isolation calls, suggesting that changes in hearing sensitivity evolved in response to frequency changes of echolocation and social calls. Overall, our study provides the most comprehensive comparative assessment of bat hearing capacities to date and highlights the evolutionary pressures acting on their sensory perception.     

Unraveling of the polymorphic C lambda 2-C lambda 3 amplification and the Ke+Oz- polymorphism in the human Ig lambda locus

Two polymorphisms of the human Ig(lambda) (IGL) locus have been described. The first polymorphism concerns a single, 2- or 3-fold amplification of 5.4 kb of DNA in the C(lambda)2-C(lambda)3 region. The second polymorphism is the Mcg(-)Ke(+)Oz(-) isotype, which has only been defined via serological analyses in Bence-Jones proteins of multiple myeloma patients and was assumed to be encoded by a polymorphic C(lambda)2 segment because of its high homology with the Mcg(-)Ke(-)Oz(-) C(lambda)2 isotype. It has been speculated that the Mcg(-)Ke(+)Oz(-) isotype might be encoded by a C(lambda) gene segment of the amplified C(lambda)2-C(lambda)3 region. We now unraveled both IGL gene polymorphisms. The amplification polymorphism appeared to result from a duplication, triplication, or quadruplication of a functional J-C(lambda)2 region and is likely to have originated from unequal crossing over of the J-C(lambda)2 and J-C(lambda)3 region via a 2.2-kb homologous repeat. The amplification polymorphism was found to result in the presence of one to five extra functional J-C(lambda)2 per genome regions, leading to decreased Ig(kappa):Ig(lambda) ratios on normal peripheral blood B cells. Via sequence analysis, we demonstrated that the Mcg(-)Ke(+)Oz(-) isotype is encoded by a polymorphic C(lambda)2 segment that differs from the normal C(lambda)2 gene segment at a single nucleotide position. This polymorphism was identified in only 1.5% (2 of 134) of individuals without J-C(lambda)2 amplification polymorphism and was not found in the J-C(lambda)2 amplification polymorphism of 44 individuals, indicating that the two IGL gene polymorphisms are not linked.     

Disease Burden of 32 Infectious Diseases in the Netherlands, 2007-2011

BackgroundInfectious disease burden estimates provided by a composite health measure give a balanced view of the true impact of a disease on a population, allowing the relative impact of diseases that differ in severity and mortality to be monitored over time. This article presents the first national disease burden estimates for a comprehensive set of 32 infectious diseases in the Netherlands.ConclusionsFor guiding and supporting public health policy decisions regarding the prioritisation of interventions and preventive measures, estimates of disease burden and the comparison of burden between diseases can be informative. Although the collection of disease-specific parameters and estimation of incidence is a process subject to continuous improvement, the current study established a baseline for assessing the impact of future public health initiatives.     

Estrogen receptor subtype β2 is involved in neuromast development in zebrafish (Danio rerio) larvae

Estrogens are known to play a role in both reproductive and non-reproductive functions in mammals. Estrogens and their receptors are involved in the development of the central nervous system (brain development, neuronal survival and differentiation) as well as in the development of the peripheral nervous system (sensory-motor behaviors). In order to decipher possible functions of estrogens in early development of the zebrafish sensory system, we investigated the role of estrogen receptor β₂ (ERβ₂) by using a morpholino (MO) approach blocking erβ₂ RNA translation. We further investigated the development of lateral line organs by cell-specific labeling, which revealed a disrupted development of neuromasts in morphants. The supporting cells developed and migrated normally. Sensory hair cells, however, were absent in morphants' neuromasts. Microarray analysis and subsequent in situ hybridizations indicated an aberrant activation of the Notch signaling pathway in ERβ₂ morphants. We conclude that signaling via ERβ₂ is essential for hair cell development and may involve an interaction with the Notch signaling pathway during cell fate decision in the neuromast maturation process.     

Discourses,Power Negotiations and Indigenous Political Organization in Forest Partnerships: The Case of Selva de Matavén,Colombia

While much research on forest partnerships hitherto has been focused mainly on the drivers behind their formation, the kind of actors and deals involved, and the factors that promote or hinder their success, much less attention has been paid to the dynamic relationships and processes inherent in these partnerships. Based on the study of a partnership process in an indigenous reservation in Colombian Amazonia covering a variety of projects, this paper seeks to fill part of this lacuna by analyzing the partnership as a dynamic ‘discursive battlefield,’ in which objectives and actions are being constantly negotiated. Actors in the Matavén partnership strategically incorporate discursive elements in order to pursue their own interests while also endorsing those that ensure the continuation of collaboration. We conclude that discourses are embedded in partnership micro-politics. On the one hand, discursive shifts occur as a reflection of power balances at given moments. On the other hand, discourses constitute indispensable resources with the potential to both enhance individual actor’s negotiating power and to create opportunities for compromise. Within an ongoing discursive tension between ‘conservation’ and ‘indigenous autonomy,’ flexible notions such as ‘territorial ordering’ prove to be successful in allowing space for manoeuvre and granting conceptual coherence to shifts occurring ‘on the ground.’     

Structure and Function of a Novel Type of ATP-dependent Clp Protease

The Clp protease is conserved among eubacteria and most eukaryotes, and uses ATP to drive protein substrate unfolding and translocation into a chamber of sequestered proteolytic active sites. The main constitutive Clp protease in photosynthetic organisms has evolved into a functionally essential and structurally intricate enzyme. The model Clp protease from the cyanobacterium Synechococcus consists of the HSP100 molecular chaperone ClpC and a mixed proteolytic core comprised of two distinct subunits, ClpP3 and ClpR. We have purified the ClpP3/R complex, the first for a Clp proteolytic core comprised of heterologous subunits. The ClpP3/R complex has unique functional and structural features, consisting of twin heptameric rings each with an identical ClpP3₃ClpR₄ configuration. As predicted by its lack of an obvious catalytic triad, the ClpR subunit is shown to be proteolytically inactive. Interestingly, extensive modification to ClpR to restore proteolytic activity to this subunit showed that its presence in the core complex is not rate-limiting for the overall proteolytic activity of the ClpCP3/R protease. Altogether, the ClpP3/R complex shows remarkable similarities to the 20 S core of the proteasome, revealing a far greater degree of convergent evolution than previously thought between the development of the Clp protease in photosynthetic organisms and that of the eukaryotic 26 S proteasome.Proteases perform numerous tasks vital for cellular homeostasis in all organisms. Much of the selective proteolysis within living cells is performed by multisubunit chaperone-protease complexes. These proteases all share a common two-component architecture and mode of action, with one of the best known examples being the proteasome in archaebacteria, certain eubacteria, and eukaryotes (1).The 20 S proteasome is a highly conserved cylindrical structure composed of two distinct types of subunits, α and β. These are organized in four stacked heptameric rings, with two central β-rings sandwiched between two outer α-rings. Although the α- and β-protein sequences are similar, it is only the latter that is proteolytic active, with a single Thr active site at the N terminus. The barrel-shaped complex is traversed by a central channel that widens up into three cavities. The catalytic sites are positioned in the central chamber formed by the β-rings, adjacent to which are two antechambers conjointly built up by β- and α-subunits. In general, substrate entry into the core complex is essentially blocked by the α-rings, and thus relies on the associating regulatory partner, PAN and 19 S complexes in archaea and eukaryotes, respectively (1). Typically, the archaeal core structure is assembled from only one type of α- and β-subunit, so that the central proteolytic chamber contains 14 catalytic active sites (2). In contrast, each ring of the eukaryotic 20 S complex has seven distinct α- and β-subunits. Moreover, only three of the seven β-subunits in each ring are proteolytically active (3). Having a strictly conserved architecture, the main difference between the 20 S proteasomes is one of complexity. In mammalian cells, the three constitutive active subunits can even be replaced with related subunits upon induction by γ-interferon to generate antigenic peptides presented by the class 1 major histocompatibility complex (4).Two chambered proteases architecturally similar to the proteasome also exist in eubacteria, HslV and ClpP. HslV is commonly thought to be the prokaryotic counterpart to the 20 S proteasome mainly because both are Thr proteases. A single type of HslV protein, however, forms a proteolytic chamber consisting of twin hexameric rather than heptameric rings (5). Also displaying structural similarities to the proteasome is the unrelated ClpP protease. The model Clp protease from Escherichia coli consists of a proteolytic ClpP core flanked on one or both sides by the ATP-dependent chaperones ClpA or ClpX (6). The ClpP proteolytic chamber is comprised of two opposing homo-heptameric rings with the catalytic sites harbored within (7). ClpP alone displays only limited peptidase activity toward short unstructured peptides (8). Larger native protein substrates need to be recognized by ClpA or ClpX and then translocated in an unfolded state into the ClpP proteolytic chamber (9, 10). Inside, the unfolded substrate is bound in an extended manner to the catalytic triads (Ser-97, His-122, and Asp-171) and degraded into small peptide fragments that can readily diffuse out (11). Several adaptor proteins broaden the array of substrates degraded by a Clp protease by binding to the associated HSP100 partner and modifying its protein substrate specificity (12, 13). One example is the adaptor ClpS that interacts with ClpA (EcClpA) and targets N-end rule substrates for degradation by the ClpAP protease (14).Like the proteasome, the Clp protease is found in a wide variety of organisms. Besides in all eubacteria, the Clp protease also exist in mammalian and plant mitochondria, as well as in various plastids of algae and plants. It also occurs in the unusual plastid in Apicomplexan protozoan (15), a family of parasites responsible for many important medical and veterinary diseases such as malaria. Of all these organisms, photobionts have by far the most diverse array of Clp proteins. This was first apparent in cyanobacteria, with the model species Synechococcus elongatus having 10 distinct Clp proteins, four HSP100 chaperones (ClpB1–2, ClpC, and ClpX), three ClpP proteins (ClpP1–3), a ClpP-like protein termed ClpR, and two adaptor proteins (ClpS1–2) (16). Of particular interest is the ClpR variant, which has protein sequence similarity to ClpP but appears to lack the catalytic triad of Ser-type proteases (17). This diversity of Clp proteins is even more extreme in photosynthetic eukaryotes, with at least 23 different Clp proteins in the higher plant Arabidopsis thaliana, most of which are plastid-localized (18).We have recently shown that two distinct Clp proteases exist in Synechococcus, both of which contain mixed proteolytic cores. The first consists of ClpP1 and ClpP2 subunits, and associates with ClpX, whereas the other has a proteolytic core consisting of ClpP3 and ClpR that binds to ClpC, as do the two ClpS adaptors (19). Of these proteases, it is the more constitutively abundant ClpCP3/R that is essential for cell viability and growth (20, 21). It is also the ClpP3/R complex that is homologous to the single type in eukaryotic plastids, all of which also have ClpC as the chaperone partner (16). In algae and plants, however, the complexity of the plastidic Clp proteolytic core has evolved dramatically. In Arabidopsis, the core complex consists of five ClpP and four ClpR paralogs, along with two unrelated Clp proteins unique to higher plants (22). Like ClpP3/R, the plastid Clp protease in Arabidopsis is essential for normal growth and development, and appears to function primarily as a housekeeping protease (23, 24).One of the most striking developments in the Clp protease in photosynthetic organisms and Apicomplexan parasites is the inclusion of ClpR within the central proteolytic core. Although this type of Clp protease has evolved into a vital enzyme, little is known about its activity or the exact role of ClpR within the core complex. To address these points we have purified the intact Synechococcus ClpP3/R proteolytic core by co-expression in E. coli. The recombinant ClpP3/R forms a double heptameric ring complex, with each ring having a specific ClpP3/R stoichiometry and arrangement. Together with ClpC, the ClpP3/R complex degrades several polypeptide substrates, but at a rate considerably slower than that by the E. coli ClpAP protease. Interestingly, although ClpR is shown to be proteolytically inactive, its inclusion in the core complex is not rate-limiting to the overall activity of the ClpCP3/R protease. In general, the results reveal remarkable similarities between the evolutionary development of the Clp protease in photosynthetic organisms and the eukaryotic proteasome relative to their simpler prokaryotic counterparts.