Cation-independent Mannose 6-Phosphate Receptor: A COMPOSITE OF DISTINCT PHOSPHOMANNOSYL BINDING SITES*

The 300-kDa cation-independent mannose 6-phosphate receptor (CI-MPR), which contains multiple mannose 6-phosphate (Man-6-P) binding sites that map to domains 3, 5, and 9 within its 15-domain extracytoplasmic region, functions as an efficient carrier of Man-6-P-containing lysosomal enzymes. To determine the types of phosphorylated N-glycans recognized by each of the three carbohydrate binding sites of the CI-MPR, a phosphorylated glycan microarray was probed with truncated forms of the CI-MPR. Surface plasmon resonance analyses using lysosomal enzymes with defined N-glycans were performed to evaluate whether multiple domains are needed to form a stable, high affinity carbohydrate binding pocket. Like domain 3, adjacent domains increase the affinity of domain 5 for phosphomannosyl residues, with domain 5 exhibiting ∼60-fold higher affinity for lysosomal enzymes containing the phosphodiester Man-P-GlcNAc when in the context of a construct encoding domains 5–9. In contrast, domain 9 does not require additional domains for high affinity binding. The three sites differ in their glycan specificity, with only domain 5 being capable of recognizing Man-P-GlcNAc. In addition, domain 9, unlike domains 1–3, interacts with Man₈GlcNAc₂ and Man₉GlcNAc₂ oligosaccharides containing a single phosphomonoester. Together, these data indicate that the assembly of three unique carbohydrate binding sites allows the CI-MPR to interact with the structurally diverse phosphorylated N-glycans it encounters on newly synthesized lysosomal enzymes.     

Methods for assessing the burden of parasitic zoonoses: echinococcosis and cysticercosis

Cysticercosis and echinococcosis cause illness and productivity losses in human and agricultural animal populations. Recent studies suggest that these diseases have large societal impacts on endemic areas. Estimates of burden provide essential, evidence-based data for conducting cost-benefit and cost-utility analyses that will secure political will, and financial and technical resources. To evaluate the burden, the monetary and non-monetary impacts of these zoonoses on human health, agriculture and society must be considered comprehensively. In this article, we review the framework used to assess the burden of cysticercosis and echinococcosis, and the data needed to estimate the extent of the problem for societies.     

GENETIC VARIABILITY AND MOLECULAR PHYLOGENY OF DINOPHYSIS SPECIES (DINOPHYCEAE) FROM NORWEGIAN WATERS INFERRED FROM SINGLE CELL ANALYSES OF rDNA1

The objectives of this study were to determine rDNA sequences of the most common Dinophysis species in Scandinavian waters and to resolve their phylogenetic relationships within the genus and to other dinoflagellates. A third aim was to examine the intraspecific variation in D. acuminata and D. norvegica, because these two species are highly variable in both morphology and toxicity. We obtained nucleotide sequences of coding (small subunit [SSU], partial large subunit [LSU], 5.8S) and noncoding (internal transcribed spacer [ITS]1, ITS2) parts of the rRNA operon by PCR amplification of one or two Dinophysis cells isolated from natural water samples. The three photosynthetic species D. acuminata, D. acuta, and D. norvegica differed in only 5 to 8 of 1802 base pairs (bp) within the SSU rRNA gene. The nonphotosynthetic D. rotundata (synonym Phalacroma rotundatum[Claparède et Lachmann] Kofoid et Michener), however, differed in approximately 55 bp compared with the three photosynthetic species. In the D1 and D2 domains of LSU rDNA, the phototrophic species differed among themselves by 3 to 12 of 733 bp, whereas they differed from D. rotundata by more than 100 bp. This supports the distinction between Dinophysis and Phalacroma. In the phylogenetic analyses based on SSU rDNA, all Dinophysis species were grouped into a common clade in which D. rotundata diverged first. The results indicate an early divergence of Dinophysis within the Dinophyta. The LSU phylogenetic analyses, including 4 new and 11 Dinophysis sequences from EMBL, identified two major clades within the phototrophic species. Little or no intraspecific genetic variation was found in the ITS1–ITS2 region of single cells of D. norvegica and D. acuminata from Norway, but the delineation between these two species was not always clear.     

Opt-Out Panel Testing for HIV,Hepatitis B and Hepatitis C in an Urban Emergency Department: A Pilot Study

Objectives

Studies suggest 2 per 1000 people in Dublin are living with HIV, the level above which universal screening is advised. We aimed to assess the feasibility and acceptability of a universal opt-out HIV, Hepatitis B and Hepatitis C testing programme for Emergency Department patients and to describe the incidence and prevalence of blood-borne viruses in this population.

Methods

An opt-out ED blood borne virus screening programme was piloted from March 2014 to January 2015. Patients undergoing blood sampling during routine clinical care were offered HIV 1&2 antibody/antigen assay, HBV surface antigen and HCV antibody tests. Linkage to care where necessary was co-ordinated by the study team. New diagnosis and prevalence rates were defined as the new cases per 1000 tested and number of positive tests per 1000 tested respectively.

Results

Over 45 weeks of testing, of 10,000 patient visits, 8,839 individual patient samples were available for analysis following removal of duplicates. A sustained target uptake of >50% was obtained after week 3. 97(1.09%), 44(0.49%) and 447(5.05%) HIV, Hepatitis B and Hepatitis C tests were positive respectively. Of these, 7(0.08%), 20(0.22%) and 58(0.66%) were new diagnoses of HIV, Hepatitis B and Hepatitis C respectively. The new diagnosis rate for HIV, Hepatitis B and Hepatitis C was 0.8, 2.26 and 6.5 per 1000 and study prevalence for HIV, Hepatitis B and Hepatitis C was 11.0, 5.0 and 50.5 per 1000 respectively.

Conclusions

Opt-out blood borne viral screening was feasible and acceptable in an inner-city ED. Blood borne viral infections were prevalent in this population and newly diagnosed cases were diagnosed and linked to care. These results suggest widespread blood borne viral testing in differing clinical locations with differing population demographic risks may be warranted.     

Metabolic control analysis is helpful for informed genetic manipulation of oilseed rape (Brassica napus) to increase seed oil content

Top-down control analysis (TDCA) is a useful tool for quantifying constraints on metabolic pathways that might be overcome by biotechnological approaches. Previous studies on lipid accumulation in oilseed rape have suggested that diacylglycerol acyltransferase (DGAT), which catalyses the final step in seed oil biosynthesis, might be an effective target for enhancing seed oil content. Here, increased seed oil content, increased DGAT activity, and reduced substrate:product ratio are demonstrated, as well as reduced flux control by complex lipid assembly, as determined by TDCA in Brassica napus (canola) lines which overexpress the gene encoding type-1 DGAT. Lines overexpressing DGAT1 also exhibited considerably enhanced seed oil content under drought conditions. These results support the use of TDCA in guiding the rational selection of molecular targets for oilseed modification. The most effective lines had a seed oil increase of 14%. Moreover, overexpression of DGAT1 under drought conditions reduced this environmental penalty on seed oil content.     

Fertilization acid of sea urchin eggs: Evidence that it is H+, not CO2

The report of R. J. Gillies, M. P. Rosenberg, and D. W. Deamer (1981, J. Cell. Phys., 108, 115–122) that sea urchin fertilization acid is anaerobically produced CO₂, was reinvestigated by inseminating Strongylocentrotus purpuratus eggs in HCO^?₃-free seawater, then bubbling the seawater with N₂ to remove volatile acid. Fertilization acid production occurred in HCO^?₃-free seawater and with N₂-bubbling, the pH rose 0.28 ± 0.08 unit, significantly less than the rise of 0.63 ± 0.14 unit during N₂-bubbling of HCO^?₃-free seawater that had been acidified with CO₂ and similar to the rise of 0.18 ± 0.07 unit when acidification was with HCl. We conclude that most, if not all, of the sea urchin fertilization acid is nonvolatile and thus is not CO₂; since it is not a weak acid, it must be H⁺.     

GENOME‐WIDE INVESTIGATION OF REPRODUCTIVE ISOLATION IN EXPERIMENTAL LINEAGES AND NATURAL SPECIES OF NEUROSPORA: IDENTIFYING CANDIDATE REGIONS BY MICROARRAY‐BASED GENOTYPING AND MAPPING

Inherent incompatibilities between genetic components from genomes of different species may cause intrinsic reproductive isolation. In evolution experiments designed to instigate speciation in laboratory populations of the filamentous fungus Neurospora, we previously discovered a pair of incompatibility loci (dfe and dma) that interact negatively to cause severe defects in sexual reproduction. Here we show that the dfe‐dma incompatibility also is a significant cause of genetic isolation between two naturally occurring species of Neurospora (N. crassa and N. intermedia). The strong incompatibility interaction has a simple genetic basis (two biallelic loci) and antagonistic epistasis occurs between heterospecific alleles only, consistent with the Dobzhansky–Muller model of genic incompatibility. We developed microarray‐based, restriction‐site associated DNA (RAD) markers that identified ～1500 polymorphisms between the genomes of the two species, and constructed the first interspecific physical map of Neurospora. With this new mapping resource, the approximate genomic locations of the incompatibility loci were determined using three different approaches: genome scanning, bulk‐segregant analyses, and introgression. These population, quantitative, and classical genetics methods concordantly identified two candidate regions, narrowing the search for each incompatibility locus to only ～2% of the nuclear genome. This study demonstrates how advances in high‐throughput, genome‐wide genotyping can be applied to mapping reproductive isolation genes and speciation research.     

Cost of resistance and tolerance under competition: the defense-stress benefit hypothesis

Defense costs provide a major explanation for why plants in nature have not evolved to be better defended against pathogens and herbivores; however, evidence for defense costs is often lacking. Plants defend by deploying resistance traits that reduce damage, and tolerance traits that reduce the fitness effects of damage. We first tested the defense-stress cost (DSC) hypothesis that costs of defenses increase and become important under competitive stress. In a greenhouse experiment, uniparental maternal families of the host plant Arabis perennans were grown in the presence and absence of the bunch grass Bouteloua gracilis and the herbivore Plutella xylostella. Costs of resistance and tolerance manifest as reduced growth in the absence of herbivory were significant when A. perennans grew alone, but not in the competitive environment, in contrast to the DSC hypothesis. We then tested the defense-stress benefit (DSB) hypothesis that plant defenses may benefit plants in competitive situations thereby reducing net costs. For example, chemical resistance agents and tolerance may also have functions in competitive interactions. To test the DSB hypothesis, we compared differentially competitive populations for defense costs, assuming that poorer competitors from less dense habitats were less likely to have evolved defenses that also function in competition. Without competitive benefits of defenses, poorer competitors were expected to have higher net costs of defenses under competition in accordance with DSB. Populations of A. perennans and A. drummondii that differed dramatically in competitiveness were compared for costs, and as the DSB hypothesis predicts, only the poor competitor population showed costs of resistance under competition. However, cost of tolerance under competition did not differ among populations, suggesting that the poor competitors might have evolved a general stress tolerance. Although the DSC hypothesis may explain cases where defense costs increase under stress, the DSB hypothesis may explain some cases where costs decrease under competitive stress.     

Exploring the Spatial Association between Social Deprivation and Cardiovascular Disease Mortality at the Neighborhood Level

Cardiovascular disease (CVD), the leading cause of death in the United States, is impacted by neighborhood-level factors including social deprivation. To measure the association between social deprivation and CVD mortality in Harris County, Texas, global (Ordinary Least Squares (OLS) and local (Geographically Weighted Regression (GWR)) models were built. The models explored the spatial variation in the relationship at a census-tract level while controlling for age, income by race, and education. A significant and spatially varying association (p < .01) was found between social deprivation and CVD mortality, when controlling for all other factors in the model. The GWR model provided a better model fit over the analogous OLS model (R² = .65 vs. .57), reinforcing the importance of geography and neighborhood of residence in the relationship between social deprivation and CVD mortality. Findings from the GWR model can be used to identify neighborhoods at greatest risk for poor health outcomes and to inform the placement of community-based interventions.