Casparian strip diffusion barrier in Arabidopsis is made of a lignin polymer without suberin.

Casparian strips are ring-like cell-wall modifications in the root endodermis of vascular plants. Their presence generates a paracellular barrier, analogous to animal tight junctions, that is thought to be crucial for selective nutrient uptake, exclusion of pathogens, and many other processes. Despite their importance, the chemical nature of Casparian strips has remained a matter of debate, confounding further molecular analysis. Suberin, lignin, lignin-like polymers, or both, have been claimed to make up Casparian strips. Here we show that, in Arabidopsis, suberin is produced much too late to take part in Casparian strip formation. In addition, we have generated plants devoid of any detectable suberin, which still establish functional Casparian strips. In contrast, manipulating lignin biosynthesis abrogates Casparian strip formation. Finally, monolignol feeding and lignin-specific chemical analysis indicates the presence of archetypal lignin in Casparian strips. Our findings establish the chemical nature of the primary root-diffusion barrier in Arabidopsis and enable a mechanistic dissection of the formation of Casparian strips, which are an independent way of generating tight junctions in eukaryotes.

Microglia/macrophages migrate through retinal epithelium barrier by a transcellular route in diabetic retinopathy: role of PKCζ in the Goto Kakizaki rat model.

Diabetic retinopathy is associated with ocular inflammation, leading to retinal barrier breakdown, macular edema, and visual cell loss. We investigated the molecular mechanisms involved in microglia/macrophages trafficking in the retina and the role of protein kinase Cζ (PKCζ) in this process. Goto Kakizaki (GK) rats, a model for spontaneous type 2 diabetes were studied until 12 months of hyperglycemia. Up to 5 months, sparse microglia/macrophages were detected in the subretinal space, together with numerous pores in retinal pigment epithelial (RPE) cells, allowing inflammatory cell traffic between the retina and choroid. Intercellular adhesion molecule-1 (ICAM-1), caveolin-1 (CAV-1), and PKCζ were identified at the pore border. At 12 months of hyperglycemia, the significant reduction of pores density in RPE cell layer was associated with microglia/macrophages accumulation in the subretinal space together with vacuolization of RPE cells and disorganization of photoreceptors outer segments. The intraocular injection of a PKCζ inhibitor at 12 months reduced iNOS expression in microglia/macrophages and inhibited their migration through the retina, preventing their subretinal accumulation. We show here that a physiological transcellular pathway takes place through RPE cells and contributes to microglia/macrophages retinal trafficking. Chronic hyperglycemia causes alteration of this pathway and subsequent subretinal accumulation of activated microglia/macrophages.

Portulaca granulato-stellulata new for El Hierro Islands( Canary Islands).

Portulaca granulato-stellulata (Poellnitz) C. Ricceri & P. V. Arrigoni is a subcosmopolitan plant of uncertain origin (DANIN et al., 1978; DANIN, 2000). It has been recently reported from Tenerife Island (DANIN & REYES-BETANCORT, 2006), the first reference for the Canary Islands, since prior to this, the taxon had not been detected from any of the Macaronesian islands. Its presence was undetected due to its inclusion within the complex Portulaca oleracea sensu lato (HANSEN & SUNDING, 1993: 170; STIERSTORFER & GAISBERG, 2006).

Evaluation of an International Barrier Corporation Barrier, HR-532, 1990

In 1986, the Iowa DOT installed 700 feet of International Barrier Corporation (IBC) barrier between the 1-235 eastbound off ramp and the adjacent eastbound loop on ramp at 8th Street in West Des Moines. It is a 3 foot 6 inch high sand-filled galvanized sheet metal barrier. The bid price on this project was $130 per lineal foot. It was evaluated annually for four years. During this time, there have been no severe accidents where vehicles hit the barrier. There are scrapes and dents indicating minor accidents. The barrier has performed very well and required no maintenance. Due to its initial cost, the IBC barrier is not as cost-effective as portland cement concrete barrier rails.

Islands of euchromatin-like sequence and expressed polymorphic sequences within the short arm of human chromosome 21.

The goals of the human genome project did not include sequencing of the heterochromatic regions. We describe here an initial sequence of 1.1 Mb of the short arm of human chromosome 21 (HSA21p), estimated to be 10% of 21p. This region contains extensive euchromatic-like sequence and includes on average one transcript every 100 kb. These transcripts show multiple inter- and intrachromosomal copies, and extensive copy number and sequence variability. The sequencing of the "heterochromatic" regions of the human genome is likely to reveal many additional functional elements and provide important evolutionary information.

Evaluation of "FIBERMESH" Synthetic Fibers in P.C. Concrete Bridge Barrier Rail, MLR-88-17, 1988

Ten bridges were chosen to have their concrete barrier rails constructed with one rail having "Fibermesh" synthetic fibers added and the other rail without the fibers. The rails were constructed in 1985, 1986, or 1987. All the bridges were inspected in 1988 and no consistent reduction in cracking was achieved using Fibermesh fibers in the p.c. concrete bridge barrier rails.

Role of the epithelial sodium channel (ENaC) in the epidermal barrier function of the skin

Abstract In humans, the skin is the largest organ of the body, covering up to 2m2 and weighing up to 4kg in an average adult. Its function is to preserve the body from external insults and also to retain water inside. This barrier function termed epidermal permeability barrier (EPB) is localized in the functional part of the skin: the epidermis. For this, evolution has built a complex structure of cells and lipids sealing the surface, the stratum corneum. The formation of this structure is finely tuned since it is not only formed once at birth, but renewed all life long. This active process gives a high plasticity and reactivity to skin, but also leads to various pathologies. ENaC is a sodium channel extensively studied in organs like kidney and lung due to its importance in regulating sodium homeostasis and fluid volume. It is composed of three subunits α, ß and r which are forming sodium selective channel through the cell membrane. Its presence in the skin has been demonstrated, but little is known about its physiological role. Previous work has shown that αENaC knockout mice displayed an abnormal epidermis, suggesting a role in differentiation processes that might be implicated in the EPB. The principal aim of this thesis has been to study the consequences for EPB function in mice deficient for αENaC by molecular and physiological means and to investigate the underlying molecular mechanisms. Here, the barrier function of αENaC knockout pups is impaired. Apparently not immediately after birth (permeability test) but 24h later, when evident water loss differences appeared compared to wildtypes. Neither the structural proteins of the epithelium nor the tights junctions showed any obvious alterations. In contrary, stratum corneum lipid disorders are most likely responsible for the barrier defect, accompanied by an impairment of skin surface acidification. To analyze in details this EPB defect, several hypotheses have been proposed: reduced sensibility to calcium which is the key activator far epidermal formation, or modification of ENaC-mediated ion fluxes/currents inside the epidermis. The cellular localization of ENaC and the action in the skin of CAPl, a positive regulator of ENaC, have been also studied in details. In summary, this study clearly demonstrates that ENaC is a key player in the EPB maintenance, because αENaC knockout pups are not able to adapt to the new environment (ex utero) as efficiently as the wildtypes, most likely due to impaired of sodium handling inside the epidermis. Résumé Chez l'homme, la peau est le plus grand organe, couvrant presque 2m2 et pesant près de 4kg chez l'adulte. Sa fonction principale est de protéger l'organisme des agressions extérieures mais également de conserver l'eau à l'intérieur du corps. Cette fonction nommée barrière épithéliale est localisée dans la partie fonctionnelle de la peau : l'épiderme. A cette fin, l'évolution s'est dotée d'une structure complexe composée de cellules et de lipides recouvrant la surface, la couche cornée. Sa formation est finement régulée, car elle n'est pas seulement produite à la naissance mais constamment renouvelée tout au long de la vie, ce qui lui confère une grande plasticité mais ce qui est également la cause de nombreuses pathologies. ENaC est un canal sodique très étudié dans le rein et le poumon pour son importance dans la régulation de l'homéostasie sodique et la régulation du volume du milieu intérieur. Il est composé de 3 sous unités, α, ß et y qui forment un pore sélectif pour le sodium dans les membranes. Ce canal est présent dans la peau mais sa fonction n'y est pas connue. Des travaux précédents ont pu montrer que les souris dont le gène codant pour αENaC a été invalidé présentent un épiderme pathologique, suggérant un rôle dans la différentiation et pourrait même être impliqué dans la barrière épithéliale. Le but de cette thèse fut l'étude de la barrière dans ces souris knockouts avec des méthodes moléculaires et physiologiques et la caractérisation des mécanismes moléculaire impliqués. Dans ce travail, il a été montré que les souris mutantes présentaient un défaut de la barrière. Ce défaut n'est pas visible immédiatement à la naissance (test de perméabilité), mais 24h plus tard, lorsque les tests de perte d'eau transépithéliale montrent une différence évidente avec les animaux contrôles. Ni les protéines de structures ni les jonctions serrées de l'épiderme ne présentaient d'imperfections majeures. A l'inverse, les lipides de la couche cornée présentaient un problème de maturation (expliquant le phénotype de la barrière), certainement consécutif au défaut d'acidification à la surface de la peau que nous avons observé. D'autres mécanismes ont été explorées afin d'investiguer cette anomalie de la barrière, comme la réduction de sensibilité au calcium qui est le principal activateur de la formation de l'épiderme, ou la modification des flux d'ions entre les couches de l'épiderme. La localisation cellulaire d'ENaC, et l'action de son activateur CAPl ont également été étudiés en détails. En résumé, cette étude démontre clairement qu'ENaC est un acteur important dans la formation de la barrière épithéliale, car la peau des knockouts ne s'adapte pas aussi bien que celle des sauvages au nouvel environnement ex utero à cause de la fonction d'ENaC dans les mouvements de sodium au sein même de l'épiderme. Résumé tout public Chez l'homme, la peau est le plus grand organe, couvrant presque 2m2 et pesant près de 4kg chez l'adulte. Sa fonction principale est de protéger l'organisme des agressions extérieures mais également de conserver l'eau à l'intérieur du corps. Cette fonction nommée barrière épithéliale est localisée dans la partie fonctionnelle de la peau : l'épiderme. A cette fin, l'évolution s'est dotée d'une structure complexe composée de cellules et de lipides recouvrant la surface, la couche cornée. Sa formation est finement régulée, car elle n'est pas seulement produite à la naissance mais constamment renouvelée tout au long de la vie, ce qui lui confère une grande plasticité mais ce qui est également la cause de nombreuses maladies. ENaC est une protéine formant un canal qui permet le passage sélectif de l'ion sodium à travers la paroi des cellules. Il est très étudié dans le rein pour son importance dans la récupération du sel lors de la concentration de l'urine. Ce canal est présent dans la peau mais sa fonction n'y est pas connue. Des travaux précédents ont pu montrer que les souris où le gène codant pour αENaC a été invalidé présentent un épiderme pathologique, suggérant un rôle dans la peau et plus particulièrement la fonction de barrière de l'épiderme. Le but de cette thèse fut l'étude de la fonction de barrière dans ces souris mutantes, au niveau tissulaire et cellulaire. Dans ce travail, il a été montré que les souris mutantes présentaient une peau plus perméable que celle des animaux contrôles, grâce à une machine mesurant la perte d'eau à travers la peau. Ce défaut n'est visible que 24h après la naissance, mais nous avons pu montrer que les animaux mutants perdaient quasiment 2 fois plus d'eau que les contrôles. Au niveau moléculaire, nous avons pu montrer que ce défaut provenait d'un problème de maturation des lipides qui composent la barrière de la peau. Cette maturation est incomplète vraisemblablement à cause d'un défaut de mouvement des ions dans les couches les plus superficielles de l'épiderme, et cela à cause de l'absence du canal ENaC. En résumé, cette étude démontre clairement qu'ENaC est un acteur important dans la formation de la barrière épithéliale, car la peau des mutants ne s'adapte pas aussi bien que celle des sauvages au nouvel environnement ex utero à cause de la fonction d'ENaC dans les mouvements de sodium au sein même de l'épiderme.

Deleterious Actions Of Vegf On The Blood Retinal Barrier And Photoreceptor Survival In The Light-damage Model

Purpose: The retinal balance between pro- and anti-angiogenic factors is critical for angiogenesis control, but is also involved in cell survival. We previously reported upregulation of VEGF and photoreceptor (PR) cell death in the Light-damage (LD) model. Preliminary results showed that anti-VEGF can rescue PR from cell death. Thus, we investigated the role of VEGF on the retina and we herein described the effect of anti-VEGF antibody delivered by lentiviral gene transfer in this model.Methods: To characterize the action of VEGF during the LD, we exposed Balb/c mice subretinally injected with LV-anti-VEGF, or not, to 5'000 lux for 1h. We next evaluated the retinal function, PR survival and protein expression (VEGF, VEGFR1/2, Src, PEDF, p38MAPK, Akt, Peripherin, SWL-opsin) after LD. We analyzed Blood retinal barrier (BRB) integrity on flat-mounted RPE and cryosections stained with β-catenin, ZO-1, N-cadherin and albumin.Results: Results indicate that the VEGF pathway is modulated after LD. LD leads to extravascular albumin leakage and BRB breakdown: β-catenin, ZO-1 and N-cadherin translocate to the cytoplasm of RPE cells showing loss of cell cohesion. This phenomenon is in adequacy with the VEGF time-course expression. Assessment of the retinal function reveals that PR rescue correlates with the level of LV-anti-VEGF expression. Rhodopsin content was higher in the LV-anti-VEGF group than in controls and measures of the ONL thickness indicate that LV-anti-VEGF preserves by 82% the outer nuclear layer from degeneration. Outer segments (OS) appeared well organized with an appropriate length in the LV-anti-VEGF group compared to controls, and the expression of SWL-opsin is maintained in the OS without being mislocalized as in the LV-GFP group. Finally, LV-anti-VEGF treatment prevents BRB breakdown and maintained RPE cell integrity.Conclusions: This study involves VEGF in LD and highlights the prime importance of the BRB integrity for PR survival. Taken together, these results show that anti-VEGF is neuroprotective in this model and maintains functional PR layer in LD-treated mice.

The Individualized Genetic Barrier Predicts Treatment Response in a Large Cohort of HIV-1 Infected Patients.

The success of combination antiretroviral therapy is limited by the evolutionary escape dynamics of HIV-1. We used Isotonic Conjunctive Bayesian Networks (I-CBNs), a class of probabilistic graphical models, to describe this process. We employed partial order constraints among viral resistance mutations, which give rise to a limited set of mutational pathways, and we modeled phenotypic drug resistance as monotonically increasing along any escape pathway. Using this model, the individualized genetic barrier (IGB) to each drug is derived as the probability of the virus not acquiring additional mutations that confer resistance. Drug-specific IGBs were combined to obtain the IGB to an entire regimen, which quantifies the virus' genetic potential for developing drug resistance under combination therapy. The IGB was tested as a predictor of therapeutic outcome using between 2,185 and 2,631 treatment change episodes of subtype B infected patients from the Swiss HIV Cohort Study Database, a large observational cohort. Using logistic regression, significant univariate predictors included most of the 18 drugs and single-drug IGBs, the IGB to the entire regimen, the expert rules-based genotypic susceptibility score (GSS), several individual mutations, and the peak viral load before treatment change. In the multivariate analysis, the only genotype-derived variables that remained significantly associated with virological success were GSS and, with 10-fold stronger association, IGB to regimen. When predicting suppression of viral load below 400 cps/ml, IGB outperformed GSS and also improved GSS-containing predictors significantly, but the difference was not significant for suppression below 50 cps/ml. Thus, the IGB to regimen is a novel data-derived predictor of treatment outcome that has potential to improve the interpretation of genotypic drug resistance tests.

Citrobacter rodentium Requires Intestinal Neural Wiskott-Aldrich Syndrome Protein (N-WASp) for Actin Pedestal Formation, Colonization and Epithelial Barrier Disruption In Vivo

Background: Citrobacter rodentium is a natural mouse pathogen that is genetically closelyrelated to the human enteric pathogens enteropathogenic and enterohemorrhagic E. coli.Among the repertoire of conserved virulence factors that these pathogens deliver via typeIII secretion, Tir and EspF are responsible for the formation of characteristic actin-richpedestals and disruption of tight junction integrity, respectively. There is evidence In Vitrothese effectors accomplish this, at least in part, by subverting the normal host cellularfunctions of N-WASP, a critical regulator of branched chain actin assembly. Although NWASPhas been shown to be involved in pedestal formation In Vitro, the requirements ofN-WASP-mediated actin pedestals for intestinal colonization by attaching/effacing (A/E)pathogens In Vivo is not known. Furthermore, it is not known whether N-WASP is requiredfor EspF-mediated tight junction disruption. Methods: To investigate the role of N-WASPin the gut epithelium, we generated mice with intestine-specific deletion of N-WASP(iNWKO), by mating mice homozygous for a floxed N-WASP allele (N-WASPL2L/L2L) tomice expressing Cre recombinase under the villin promoter. Separately housed groups ofWT and iNWKO mice were inoculated with 5x108 GFP-expressing C. rodentium by intragastriclavage. Stool was collected 2, 4, 7, and 12 days after infection, and recoverablecolony forming units (CFUs) of C. rodentium were quantified by plating serial dilutions ofhomogenized stool on MacConkey's agar. GFP+ colonies were counted after 24 hoursincubation at 37°C. The presence of actin pedestals was investigated by electron microscopy(EM), and tight junction morphology was assessed by immunofluorescence staining ofoccludin, ZO-1 and claudin-2. Results: C. rodentium infection did not result in mortalityin WT or iNWKO mice. Compared to controls, iNWKO mice exhibited higher levels ofbacterial shedding during the first 4 days of infection (day 4 average: WT 5.2x104 CFU/gvs. iNWKO 4.7x105 CFU/g, p=0.08), followed by a more rapid clearance of C. rodentium, (day7-12 average: WT 2x106 CFU/g vs. iNWKO 2.7x105, p=0.01). EM and immunofluorescencerevealed the complete lack of actin pedestals in iNWKO mice and no mucosa-associatedGFP+ C. rodentium by day 7. WT controls exhibited tight junction disruption, reflected byaltered distribution of ZO-1, whereas iNWKO mice had no change in the pattern of ZO-1.Conclusion: Intestinal N-WASP is required for actin pedestal formation by C. rodentium InVivo, and ablation of N-WASP is associated with more rapid bacterial clearance and decreasedability of C. rodentium to disrupt intercellular junctions.

Mites as biological tags of their hosts.

Movements and spatial distribution of host populations are expected to shape the genetic structure of their parasite populations. Comparing the genetic patterns of both interacting species may improve our understanding of their evolutionary history. Moreover, genetic analyses of parasites with horizontal transmission may serve as indicators of historical events or current demographic processes that are not apparent in the genetic signature of their hosts. Here, we compared mitochondrial variation in populations of the ectoparasitic mite Spinturnix myoti with the genetic pattern of its host, the Maghrebian bat Myotis punicus in North Africa and in the islands of Corsica and Sardinia. Mite mitochondrial differentiation among populations was correlated with both host mitochondrial and nuclear differentiation, suggesting spatial co-differentiation of the lineages of the two interacting species. Therefore our results suggest that parasite dispersal is exclusively mediated by host movements, with open water between landmasses as a main barrier for host and parasite dispersal. Surprisingly the unique presence of a continental European mite lineage in Corsica was inconsistent with host phylogeographical history and strongly suggests the former presence of European mouse-eared bats on this island. Parasites may thus act as biological tags to reveal the presence of their now locally extinct host.

Caveolin expression changes in the neurovascular unit after juvenile traumatic brain injury: signs of blood-brain barrier healing?

Traumatic brain injury (TBI) is one of the major causes of death and disability in pediatrics, and results in a complex cascade of events including the disruption of the blood-brain barrier (BBB). A controlled-cortical impact on post-natal 17 day-old rats induced BBB disruption by IgG extravasation from 1 to 3 days after injury and returned to normal at day 7. In parallel, we characterized the expression of three caveolin isoforms, cav-1, cav-2 and cav-3. While cav-1 and cav-2 are expressed on endothelial cells, both cav-1 and cav-3 were found to be present on reactive astrocytes, in vivo and in vitro. Following TBI, cav-1 expression was increased in blood vessels at 1 and 7 days in the perilesional cortex. An increase of vascular cav-2 expression was observed 7 days after TBI. In contrast, astrocytic cav-3 expression decreased 3 and 7 days after TBI. Activation of eNOS (via its phosphorylation) was detected 1 day after TBI and phospho-eNOS was detected both in association with blood vessels and with astrocytes. The molecular changes involving caveolins occurring in endothelial cells following juvenile-TBI might participate, independently of eNOS activation, to a mechanism of BBB repair while, they might subserve other undefined roles in astrocytes.

Fish passage assessment at the most downstream barrier of the Ebro River (NE Iberian Peninsula)

Fish passage at artificial barriers is necessary for the conservation of healthy fish stocks. The first barrier that migratory fish encounter when ascending the Ebro River is the Xerta Weir, where a pool-type fishway was constructed in 2008. From 2007 to 2010, boat electrofishing surveys were conducted in the Ebro River downstream of the Xerta Weir to assess the potential pool of species that could use the fishway. Nine native and 12 exotic species were captured, the latter comprising 62 % of the relative abundance and 70 % of the biomass. A combination of video recording, electrofishing and trapping was used to assess the effectiveness of the fishway in facilitating the passage of fish. Eight species were detected using the fishway, of which five were native (Liza ramada, Anguilla anguilla, Barbus graellsii, Gobio lozanoi and Salaria fluviatilis) and three exotic (Alburnus alburnus, Cyprinus carpio and Rutilus rutilus). Only L. ramada used the fishway in substantial numbers. The rate of fish passage was the highest from June to August and decreased afterwards. The effectiveness of the fishway might be lowered by areas of turbulence within the fishway and by distraction flows from a nearby hydropower station