Clusterin (Apo J) Protects Against In Vitro Amyloid-β(1–40) Neurotoxicity

Abstract: Clusterin is a secreted glycoprotein that is markedly induced in many disease states and after tissue injury. In the CNS, clusterin expression is elevated in neuropathological conditions such as Alzheimer's disease (AD), where it is found associated with amyloid-β (Aβ) plaques. Clusterin also coprecipitates with Aβ from CSF, suggesting a physiological interaction with Aβ. Given this interaction with Aβ, the goal of this study was to determine whether clusterin could modulate Aβ neurotoxicity. A mammalian recombinant source of human clusterin was obtained by stable transfection of hamster kidney fibroblasts with pADHC-9, a full-length human cDNA clone for clusterin. Recombinant clusterin obtained from this cell line, as well as a commercial source of native clusterin purified from serum, afforded dose-dependent neuroprotection against Aβ(1–40) when tested in primary rat mixed hippocampal cultures. Clusterin afforded substoichiometric neuroprotection against several lots of Aβ(1–40) but not against H₂O₂ or kainic acid excitotoxicity. These results suggest that the elevated expression of clusterin found in AD brain may have effects on subsequent amyloid-β plaque pathology.     

Testing the abundant‐centre hypothesis using intertidal porcelain crabs along the Chilean coast: linking abundance and life‐history variation

Aim The abundant‐centre hypothesis (ACH) is based on the assumption that physiological constraints limit populations at the edges of their distributional range, yet the geographical variation of physiological performance or life‐history traits has rarely been examined. Here we examine the applicability of the ACH in a marine system by testing whether physiological predictions are reflected in large‐scale variations of life‐history traits. Location The Chilean coast (18°–42° S), encompassing more than 2500 km along the Pacific coast of South America. Methods Five porcelain crab species (Petrolisthes granulosus, Petrolisthes laevigatus, Petrolisthes tuberculatus, Petrolisthes violaceus and Allopetrolisthes angulosus) were sampled on intertidal boulder beaches at 13 sampling sites. For each species and site we evaluated: (1) relative abundance (density), (2) maximum size, (3) size at maturity, (4) sex ratio, (5) proportion of ovigerous females, and (6) presence of recruits. The shape of the spatial distribution of each trait was evaluated statistically against the prediction of four hypothetical models (normal, ramped‐south, ramped‐north and abundant‐edge). Results The relative abundance and life‐history traits showed different spatial patterns among species. Relative abundance (across sites) was fitted by a normal model in only two species. No model fitted the spatial variation in body size and size at first maturity, which showed a slight but monotonic poleward increase in all species. Sex ratio showed a prominent hump‐shaped pattern, with females prevailing in the centre of the ranges and males dominating towards the range boundaries; this pattern was statistically significant in three of the five studied species. The proportion of ovigerous females showed no clear latitudinal trends, and mature individuals were observed across most of the geographical range of the species. However, recruits tended to be absent towards the southern (poleward) boundaries of the distribution. Main conclusions The ACH does not apply to all species equally. The link between abundance and life‐history traits is complex and variable among the porcelain crab species studied. Overall, the observed patterns were consistent with the idea that equatorward boundaries might be controlled by physiological restrictions mainly affecting adult survival, whereas poleward boundaries might be shaped by limitations in reproductive output and larval survival. Our results underline the importance of incorporating ecological, physiological and life‐history studies in future tests of the ACH.     

Temporal-Spatial Correlation between Angiogenesis and Corticogenesis in the Developing Chick Optic Tectum

The developing chick optic tectum is a widely used model of corticogenesis and angiogenesis. Cell behaviors involved in corticogenesis and angiogenesis share several regulatory mechanisms. In this way the 3D organizations of both systems adapt to each other. The consensus about the temporally and spatially organized progression of the optic tectum corticogenesis contrasts with the discrepancies about the spatial organization of its vascular bed as a function of the time. In order to find out spatial and temporal correlations between corticogenesis and angiogenesis, several methodological approaches were applied to analyze the dynamic of angiogenesis in the developing chick optic tectum. The present paper shows that a typical sequence of developmental events characterizes the optic tectum angiogenesis. The first phase, formation of the primitive vascular bed, takes place during the early stages of the tectal corticogenesis along which the large efferent neurons appear and begin their early differentiation. The second phase, remodeling and elaboration of the definitive vascular bed, occurs during the increase in complexity associated to the elaboration of the local circuit networks. The present results show that, apart from the well-known influence of the dorsal-ventral and radial axes as reference systems for the spatial organization of optic tectum angiogenesis, the cephalic-caudal axis also exerts a significant asymmetric influence. The term cortico-angiogenesis to describe the entire process is justified by the fact that tight correlations are found between specific corticogenic and angiogenic events and they take place simultaneously at the same position along the cephalic-caudal and radial axes.     

A Cascade of Sequentially Expressed Sucrose Transporters in the Seed Coat and Endosperm Provides Nutrition for the Arabidopsis Embryo

Developing plant embryos depend on nutrition from maternal tissues via the seed coat and endosperm, but the mechanisms that supply nutrients to plant embryos have remained elusive. Sucrose, the major transport form of carbohydrate in plants, is delivered via the phloem to the maternal seed coat and then secreted from the seed coat to feed the embryo. Here, we show that seed filling in Arabidopsis thaliana requires the three sucrose transporters SWEET11, 12, and 15. SWEET11, 12, and 15 exhibit specific spatiotemporal expression patterns in developing seeds, but only a sweet11;12;15 triple mutant showed severe seed defects, which include retarded embryo development, reduced seed weight, and reduced starch and lipid content, causing a “wrinkled” seed phenotype. In sweet11;12;15 triple mutants, starch accumulated in the seed coat but not the embryo, implicating SWEET-mediated sucrose efflux in the transfer of sugars from seed coat to embryo. This cascade of sequentially expressed SWEETs provides the feeding pathway for the plant embryo, an important feature for yield potential.     

Checklist of the helminth parasites of the genus Profundulus Hubbs, 1924 (Cyprinodontiformes,Profundulidae), an endemic family of freshwater fishes in Middle-America

From December 2012 to November 2014, 267 fish belonging to the family Profundulidae (representing nine of the 11 species of the genus Profundulus) were collected in 26 localities of Middle-America, across southern Mexico, Guatemala, and Honduras, comprising the distribution range of the genus, and analyzed for helminth parasites. Additionally, a database with all ten available published accounts of the helminth parasite fauna of this genus (the only genus within the family) was assembled. Based on both sources of information, a checklist containing all the records was compiled as a tool to address future questions in the areas of evolutionary biology, biogeography, ecology and phylogeography of this host-parasite association. The helminth parasite fauna of this fish group consists of 20 nominal species, classified in 17 genera and 14 families. It includes six species of adult digeneans, five metacercariae, two monogeneans, one adult cestode, three adult nematodes and three larval nematodes. The profundulid fishes are parasitized by a specialized group of helminth species (e.g. Paracreptotrema blancoi sensu Salgado-Maldonado et al. (2011b), Paracreptotrema profundulusi Salgado-Maldonado, Caspeta-Mandujano & Martínez Ramírez, 2011, Phyllodistomum spinopapillatum Pérez-Ponce de León, Pinacho-Pinacho, Mendoza-Garfias & García-Varela, 2015, Spinitectus humbertoi Mandujano-Caspeta & Moravec, 2000, Spinitectus mariaisabelae Caspeta-Mandujano Cabañas-Carranza & Salgado-Maldonado, 2007 and Rhabdochona salgadoi Mandujano-Caspeta & Moravec, 2000), representing the core helminth fauna that are not shared with other Middle-American fish species.     

In vivo nanoscale analysis of the dynamic synergistic interaction of Bacillus thuringiensis Cry11Aa and Cyt1Aa toxins in Aedes aegypti

The insecticidal Cry11Aa and Cyt1Aa proteins are produced by Bacillus thuringiensis as crystal inclusions. They work synergistically inducing high toxicity against mosquito larvae. It was proposed that these crystal inclusions are rapidly solubilized and activated in the gut lumen, followed by pore formation in midgut cells killing the larvae. In addition, Cyt1Aa functions as a Cry11Aa binding receptor, inducing Cry11Aa oligomerization and membrane insertion. Here, we used fluorescent labeled crystals, protoxins or activated toxins for in vivo localization at nano-scale resolution. We show that after larvae were fed solubilized proteins, these proteins were not accumulated inside the gut and larvae were not killed. In contrast, if larvae were fed soluble non-toxic mutant proteins, these proteins were found inside the gut bound to gut-microvilli. Only feeding with crystal inclusions resulted in high larval mortality, suggesting that they have a role for an optimal intoxication process. At the macroscopic level, Cry11Aa completely degraded the gastric caeca structure and, in the presence of Cyt1Aa, this effect was observed at lower toxin-concentrations and at shorter periods. The labeled Cry11Aa crystal protein, after midgut processing, binds to the gastric caeca and posterior midgut regions, and also to anterior and medium regions where it is internalized in ordered “net like” structures, leading finally to cell break down. During synergism both Cry11Aa and Cyt1Aa toxins showed a dynamic layered array at the surface of apical microvilli, where Cry11Aa is localized in the lower layer closer to the cell cytoplasm, and Cyt1Aa is layered over Cry11Aa. This array depends on the pore formation activity of Cry11Aa, since the non-toxic mutant Cry11Aa-E97A, which is unable to oligomerize, inverted this array. Internalization of Cry11Aa was also observed during synergism. These data indicate that the mechanism of action of Cry11Aa is more complex than previously anticipated, and may involve additional steps besides pore-formation activity.     

Signals from fat after injury: Plasma adipokines and ghrelin concentrations in the severely burned

IntroductionHypermetabolism is universal in the severely burned and is characterized by catabolism of lean mass and body fat with associated insulin resistance. Adipokines are likely to play a role in these changes but have not been identified to date in burn patients.MethodsFrom a single burn ICU, 17 burn patients with an expected stay >14 days were studied. Study period began within 14 days of admission. Over 7 days, plasma samples were collected for measurement of leptin, adiponectin, resistin, ghrelin, insulin, and cortisol by ELISA. For comparison, samples from 15 healthy controls of similar age, BMI, and blood glucose were obtained.ResultsMean age was 33 ± 17 years and BMI 26 ± 3.4. Average burn size was 45 ± 20% TBSA and ISS 32 ± 10 with 72% having inhalation injury; in-hospital mortality was 29%. Estimated energy needs were 3626 ± 710 kcal, of which 84 ± 21% were met by enteral feeding with intensive insulin treatment (glucose 80–110 mg/ml). Using the homeostasis model assessment of insulin resistance, burned subjects were more resistant than controls (17 ± 11.3 and 8 ± 10.0). Insulin levels were elevated (57 ± 35.6 μU/ml in burned subject vs. 26 ± 31.1 μU/ml in controls), and cortisol concentrations increased (50 ± 41.2 μg/dl vs. 12 ± 3.9 μg/dl). These traditional hormone changes were associated with increased resistin (16.6 ± 5.5 ng/ml vs. 3.8 ± 0.9 ng/ml) and decreased leptin (8.8 ± 8.9 ng/ml vs. 19.4 ± 23.5 ng/ml), adiponectin (9 ± 3.5 ng/ml vs. 17 ± 10.2 ng/ml), and ghrelin (0.37 ± 0.14 ng/ml vs.0.56 ± 0.26 ng/ml).ConclusionPatients with burns, who are characteristically hypermetabolic with hypercortisolism and insulin resistant, have significant changes in adipokine levels that appear independent of the magnitude of initial injury or metabolic derangement. In addition, suppression of ghrelin in the presence of decreased leptin and adiponectin levels in combination with increased insulin and resistin levels represent unexpected changes in the metabolic milieu of the injured patient possibly due to dramatic activation of inflammatory pathways, indicating strategies for treatment.