328 research outputs found

    Differential transcript expression between the microfilariae of the filarial nematodes, Brugia malayi and B. pahangi

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    <p>Abstract</p> <p>Background</p> <p><it>Brugia malayi </it>and <it>B. pahangi </it>are two closely related nematodes that cause filariasis in humans and animals. However, <it>B. pahangi </it>microfilariae are able to develop in and be transmitted by the mosquito, <it>Armigeres subalbatus</it>, whereas most <it>B. malayi </it>are rapidly melanized and destroyed within the mosquito hemocoel. A cross-species microarray analysis employing the <it>B. malayi </it>V2 array was carried out to determine the transcriptional differences between <it>B. malayi </it>and <it>B. pahangi </it>microfilariae with similar age distribution.</p> <p>Results</p> <p>Following microarray data analysis, a list of preferentially expressed genes in both microfilariae species was generated with a false discovery rate estimate of 5% and a signal intensity ratio of 2 or higher in either species. A total of 308 probes were preferentially expressed in both species with 149 probes, representing 123 genes, in <it>B. pahangi </it>microfilariae and 159 probes, representing 107 genes, in <it>B. malayi </it>microfilariae. In <it>B. pahangi</it>, there were 76 (62%) up-regulated transcripts that coded for known proteins that mapped into the KEGG pathway compared to 61 (57%) transcripts in <it>B. malayi </it>microfilariae. The remaining 47 (38%) transcripts in <it>B. pahangi </it>and 46 (43%) transcripts in <it>B. malayi </it>microfilariae were comprised almost entirely of hypothetical genes of unknown function. Twenty-seven of the transcripts in <it>B. pahangi </it>microfilariae coded for proteins that associate with the secretory pathway compared to thirty-nine in <it>B. malayi </it>microfilariae. The data obtained from real-time PCR analysis of ten genes selected from the microarray list of preferentially expressed genes showed good concordance with the microarray data, indicating that the microarray data were reproducible.</p> <p>Conclusion</p> <p>In this study, we identified gene transcripts that were preferentially expressed in the microfilariae of <it>B. pahangi </it>and <it>B. malayi</it>, some of which coded for known immunomodulatory proteins. These comparative transcriptome data will be of interest to researchers keen on understanding the inherent differences, at the molecular level, between <it>B. malayi </it>and <it>B. pahangi </it>microfilariae especially because these microfilariae are capable of surviving in the same vertebrate host but elicit different immune response outcomes in the mosquito, <it>Ar. subalbatus</it>.</p

    Mapping environmental injustices: pitfalls and potential of geographic information systems in assessing environmental health and equity.

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    Geographic Information Systems (GIS) have been used increasingly to map instances of environmental injustice, the disproportionate exposure of certain populations to environmental hazards. Some of the technical and analytic difficulties of mapping environmental injustice are outlined in this article, along with suggestions for using GIS to better assess and predict environmental health and equity. I examine 13 GIS-based environmental equity studies conducted within the past decade and use a study of noxious land use locations in the Bronx, New York, to illustrate and evaluate the differences in two common methods of determining exposure extent and the characteristics of proximate populations. Unresolved issues in mapping environmental equity and health include lack of comprehensive hazards databases; the inadequacy of current exposure indices; the need to develop realistic methodologies for determining the geographic extent of exposure and the characteristics of the affected populations; and the paucity and insufficiency of health assessment data. GIS have great potential to help us understand the spatial relationship between pollution and health. Refinements in exposure indices; the use of dispersion modeling and advanced proximity analysis; the application of neighborhood-scale analysis; and the consideration of other factors such as zoning and planning policies will enable more conclusive findings. The environmental equity studies reviewed in this article found a disproportionate environmental burden based on race and/or income. It is critical now to demonstrate correspondence between environmental burdens and adverse health impacts--to show the disproportionate effects of pollution rather than just the disproportionate distribution of pollution sources

    Vegetation indices for mapping canopy foliar nitrogen in a mixed temperate forest

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    Hyperspectral remote sensing serves as an effective tool for estimating foliar nitrogen using a variety of techniques. Vegetation indices (VIs) are a simple means of retrieving foliar nitrogen. Despite their popularity, few studies have been conducted to examine the utility of VIs for mapping canopy foliar nitrogen in a mixed forest context. In this study, we assessed the performance of 32 vegetation indices derived from HySpex airborne hyperspectral images for estimating canopy mass-based foliar nitrogen concentration (%N) in the Bavarian Forest National Park. The partial least squares regression (PLSR) was performed for comparison. These vegetation indices were classified into three categories that are mostly correlated to nitrogen, chlorophyll, and structural properties such as leaf area index (LAI). %N was destructively measured in 26 broadleaf, needle leaf, and mixed stand plots to represent the different species and canopy structure. The canopy foliar %N is defined as the plot-level mean foliar %N of all species weighted by species canopy foliar mass fraction. Our results showed that the variance of canopy foliar %N is mainly explained by functional type and species composition. The normalized difference nitrogen index (NDNI) produced the most accurate estimation of %N (R2CV = 0.79, RMSECV = 0.26). A comparable estimation of %N was obtained by the chlorophyll index Boochs2 (R2CV = 0.76, RMSECV = 0.27). In addition, the mean NIR reflectance (800-850 nm), representing canopy structural properties, also achieved a good accuracy in %N estimation (R2CV = 0.73, RMSECV = 0.30). The PLSR model provided a less accurate estimation of %N (R2CV = 0.69, RMSECV = 0.32). We argue that the good performance of all three categories of vegetation indices in %N estimation can be attributed to the synergy among plant traits (i.e., canopy structure, leaf chemical and optical properties) while these traits may converge across plant species for evolutionary reasons

    EFFECTS OF FIRE AND HERBIVORY ON THE STABILITY OF SAVANNA ECOSYSTEMS

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    Savanna ecosystems are characterized by the co-occurrence of trees and grass-es. In this paper, we argue that the balance between trees and grasses is, to a large extent, determined by the indirect interactive effects of herbivory and fire. These effects are based on the positive feedback between fuel load (grass biomass) and fire intensity. An increase in the level of grazing leads to reduced fuel load, which makes fire less intense and, thus, less damaging to trees and, consequently, results in an increase in woody vegetation. The system then switches from a state with trees and grasses to a state with solely trees. Similarly, browsers may enhance the effect of fire on trees because they reduce woody biomass, thus indirectly stimulating grass growth. This consequent increase in fuel load results in more intense fire and increased decline of biomass. The system then switches from a state with solely trees to a state with trees and grasses. We maintain that the interaction between fire and herbivory provides a mechanistic explanation for observed discontinuous changes in woody and grass biomass. This is an alternative for the soil degradation mechanism, in which there is a positive feedback between the amount of grass biomass and the amount of water that infiltrates into the soil. The soil degradation mechanism predicts no discontinuous chang-es, such as bush encroachment, on sandy soils. Such changes, however, are frequently ob-served. Therefore, the interactive effects of fire and herbivory provide a more plausible explanation for the occurrence of discontinuous changes in savanna ecosystems

    Dog words – or, How to think without language

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    This paper is situated in the context of debates about animals and language, and animal-human relations. It is also informed by the argument that words are neither the exclusive property of language (Motamedi Fraser 2015), nor the exclusive property of humans. The paper illustrates this point by exploring how some companion dogs make 'dog words' with their bodies and, further, how they are able/can be enabled to transform the meanings of these words by inventing and/or participating in word encounters. In the spirit of Lev Vygotsky, the paper argues that such encounters are a way of thinking with words in 'complexes.' Through a series of concrete examples, the paper shows how intimacy is integral to this thinking, in its every dimension. The ethically optimistic dimension of this analysis, however, simultaneously draws attention to how fragile are the relations between dogs, humans, and words, and how proximate intimacy is to 'other kinds of relations.' With this in mind, the paper addresses three 'other kinds of relations' that potentially limit animal-human 'talking' and thinking: scientific behaviourism, speciesism, and 'languagism.

    Loss of heterozygosity at 7p in Wilms' tumour development

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    Chromosome 7p alterations have been implicated in the development of Wilms' tumour (WT) by previous studies of tumour cytogenetics, and by our analysis of a constitutional translocation (t(1;7)(q42;p15)) in a child with WT and radial aplasia. We therefore used polymorphic microsatellite markers on 7p for a loss of heterozygosity (LOH) study, and found LOH in seven out of 77 informative WTs (9%). The common region of LOH was 7p15–7p22, which contains the region disrupted by the t(1;7) breakpoint. Four WTs with 7p LOH had other genetic changes; a germline WT1 mutation with 11p LOH, LOH at 11p, LOH at 16q, and loss of imprinting of IGF2. Analysis of three tumour-associated lesions from 7p LOH cases revealed a cystic nephroma-like area also having 7p LOH. However, a nephrogenic rest and a contralateral WT from the two other cases showed no 7p LOH. No particular clinical phenotype was associated with the WTs which showed 7p LOH. The frequency and pattern of 7p LOH demonstrated in our studies indicate the presence of a tumour suppressor gene at 7p involved in the development of Wilms' tumour. © 2000 Cancer Research Campaig
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