131 research outputs found

    Anophelinae (Diptera: Culicidae) in ausgewÀhlten Marschgebieten Niedersachsens : Bestandserfassung, Habitatbindung und Interpolation

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    Nach HIRSCH (1883) war die Malariasituation im 19. Jahrhundert in Norddeutschland am schlimmsten in Schleswig-Holstein, an der KĂŒste westlich der Elbe sowie in den Moorgebieten von Hannover und Oldenburg. Erst mit Beginn des 20. Jahrhunderts nahm dort die Zahl der Infektionen ab. Dieser RĂŒckgang wurde vielfach auf die Trockenlegung von Marsch-, Sumpf- und Moorgebieten zurĂŒckgefĂŒhrt (MAIER 2004). Aktuell wird deshalb in Teilen der Bevölkerung ein Wiederaufflackern der Malaria bzw. anderer MĂŒckenassoziierter Krankheiten als indirekte Folge von WiedervernĂ€ssungsmaßnahmen befĂŒrchtet. Hinzu kommen Klima- und weitere UmweltverĂ€nderungen, welche nach MAIER et al. (2003) Ursache fĂŒr neu auftretende oder wiederkehrende Krankheiten sein können. Mit dem Verschwinden der Malaria wurde in Deutschland kaum weitere Forschung zur Verbreitung und Ökologie der Culiciden betrieben. Das Fehlen von fundierten Daten zur Ökologie und Populationsentwicklung der prĂ€imaginalen Culicidenstadien in den heute vorhandenen LebensrĂ€umen (z.B. GrĂ€ben, Polder, WiedervernĂ€ssungsflĂ€chen, Mooren) erschwert Aussagen und Prognosen zur Verbreitung potenzieller Vektoren. Die aktuellen Untersuchungen konzentrierten sich zunĂ€chst auf die Untersuchung der aquatischen Entwicklungsstadien von Anopheles-Arten (Diptera: Culicidae) in EntwĂ€sserungsgrĂ€ben. Diese Biotope sind fĂŒr die heutige Landschaftsstruktur der Marschengebiete im Nordwesten Niedersachsens typisch, stellen dort einen hohen Anteil der WasserflĂ€chen dar und sind grundsĂ€tzlich als BrutgewĂ€sser geeignet (CRANSTON et al. 1987, MOHRIG 1969). Wesentliches Ziel der Untersuchung war zunĂ€chst die Darstellung historischer Fundgebiete, der abgesicherte Nachweis aktueller Brutgebiete verschiedener Anopheles-Arten und die Entwicklung einer standardisierten Methode zur Charakterisierung der betreffenden Biotope. Darauf aufbauend sollen mit GISTechniken, Classification and Regression Trees (CART) und Geostatistik zukĂŒnftig Möglichkeiten der Übertragung dieser Resultate auf Ă€hnlich ausgestattete LandschaftsrĂ€ume geprĂŒft werden.The disappearance of malaria from Northern Germany in the middle of the 20th century was closely linked to a significant reduction of Anopheles breeding sites as a consequence of intense drainage of marshes, swamps and moors. Nature conservation activities and the reestablishment of swamps and wetland areas may nowadays lead to a converse effect and contribute to the multiplication and spread of culicid mosquitoes again. Therefore, the monitoring of their distribution and abundance is advisable. The presented investigation concentrates on typical Lower Saxony marshland ditches and on their suitability to provide breeding facilities for Culicidae in general, and for the former malaria vectors An. atroparvus and An. messeae in particular. The study area was fixed geographically with special reference to historical vector findings, former malaria regions and current archive data. To determine the habitat preferences of the mosquitoes, a structural mapping of single ditches was performed and essential abiotic factors were recorded. Anopheles specimens regularly were found in ditches with submerse and emerse macrophytes but never in ditches with a high degree of surface coverage by swimming plants. Conductivity, pHvalue and total phosphate in the water body appear to be further variables which correlate with the occurrence and abundance of Anopheles larvae and pupae and therefore can be used for predictions. By means of geographic information systems (GIS) and geostatistical procedures, a surface related assessment of the given Anopheles densities within the ditches should now be feasible. To this end, the multivariate correlations between the empirical data were analysed by Classification and Regression Trees. The relations detected serve to predict the empirical findings to biotopes similar to the sampling sites. Furthermore, recent climate predictions will be analysed with respect to possible effects climate change may have on the distribution of Anophilinae in Lower Saxon

    Social resiliens - forandringsressourcer i to byer i GrĂžnland

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    Vi starter ud med at give en oversigt over aktuel teori om resiliensog viser, at disse teorier peger pÄ, at resiliens handler omnetvaerk og forbindelser i komplekse systemer. Derefter beskrivervi fortaellinger om social resiliens i to byer i GrÞnland,Nanortalik og Tasiilaq. Ud fra de beskrivelser diskuterer vi,hvad der kendetegner social resiliens i GrÞnland og hvordandet kan fremmes gennem konkrete projekter bÄret af lokalekrÊfter som et bidrag til den stÊrke og innovative kultur, der idisse Är udvikler sig i GrÞnland som en del af den globaleverden

    Expression quantitative trait loci are highly sensitive to cellular differentiation state

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    Blood cell development from multipotent hematopoietic stem cells to specialized blood cells is accompanied by drastic changes in gene expression for which the triggers remain mostly unknown. Genetical genomics is an approach linking natural genetic variation to gene expression variation, thereby allowing the identification of genomic loci containing gene expression modulators (eQTLs). In this paper, we used a genetical genomics approach to analyze gene expression across four developmentally close blood cell types collected from a large number of genetically different but related mouse strains. We found that, while a significant number of eQTLs (365) had a consistent “static” regulatory effect on gene expression, an even larger number were found to be very sensitive to cell stage. As many as 1,283 eQTLs exhibited a “dynamic” behavior across cell types. By looking more closely at these dynamic eQTLs, we show that the sensitivity of eQTLs to cell stage is largely associated with gene expression changes in target genes. These results stress the importance of studying gene expression variation in well-defined cell populations. Only such studies will be able to reveal the important differences in gene regulation between different ce

    Bacterial Indole as a Multifunctional Regulator of Klebsiella oxytoca Complex Enterotoxicity.

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    Gastrointestinal microbes respond to biochemical metabolites that coordinate their behaviors. Here, we demonstrate that bacterial indole functions as a multifactorial mitigator of Klebsiella grimontii and Klebsiella oxytoca pathogenicity. These closely related microbes produce the enterotoxins tilimycin and tilivalline; cytotoxin-producing strains are the causative agent of antibiotic-associated hemorrhagic colitis and have been associated with necrotizing enterocolitis of premature infants. We demonstrate that carbohydrates induce cytotoxin synthesis while concurrently repressing indole biosynthesis. Conversely, indole represses cytotoxin production. In both cases, the alterations stemmed from differ- ential transcription of npsA and npsB, key genes involved in tilimycin biosynthesis. Indole also enhances conversion of tilimycin to tilivalline, an indole analog with reduced cytotox- icity. In this context, we established that tilivalline, but not tilimycin, is a strong agonist of pregnane X receptor (PXR), a master regulator of xenobiotic detoxification and intestinal inflammation. Tilivalline binding upregulated PXR-responsive detoxifying genes and inhib- ited tubulin-directed toxicity. Bacterial indole, therefore, acts in a multifunctional manner to mitigate cytotoxicity by Klebsiella spp.: suppression of toxin production, enhanced con- version of tilimycin to tilivalline, and activation of PXR

    Parent-of-origin-specific allelic associations among 106 genomic loci for age at menarche.

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    Age at menarche is a marker of timing of puberty in females. It varies widely between individuals, is a heritable trait and is associated with risks for obesity, type 2 diabetes, cardiovascular disease, breast cancer and all-cause mortality. Studies of rare human disorders of puberty and animal models point to a complex hypothalamic-pituitary-hormonal regulation, but the mechanisms that determine pubertal timing and underlie its links to disease risk remain unclear. Here, using genome-wide and custom-genotyping arrays in up to 182,416 women of European descent from 57 studies, we found robust evidence (P < 5 × 10(-8)) for 123 signals at 106 genomic loci associated with age at menarche. Many loci were associated with other pubertal traits in both sexes, and there was substantial overlap with genes implicated in body mass index and various diseases, including rare disorders of puberty. Menarche signals were enriched in imprinted regions, with three loci (DLK1-WDR25, MKRN3-MAGEL2 and KCNK9) demonstrating parent-of-origin-specific associations concordant with known parental expression patterns. Pathway analyses implicated nuclear hormone receptors, particularly retinoic acid and γ-aminobutyric acid-B2 receptor signalling, among novel mechanisms that regulate pubertal timing in humans. Our findings suggest a genetic architecture involving at least hundreds of common variants in the coordinated timing of the pubertal transition

    Analysis of Blood Stem Cell Activity and Cystatin Gene Expression in a Mouse Model Presenting a Chromosomal Deletion Encompassing Csta and Stfa2l1

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    The cystatin protein superfamily is characterized by the presence of conserved sequences that display cysteine protease inhibitory activity (e.g., towards cathepsins). Type 1 and 2 cystatins are encoded by 25 genes of which 23 are grouped in 2 clusters localized on mouse chromosomes 16 and 2. The expression and essential roles of most of these genes in mouse development and hematopoiesis remain poorly characterized. In this study, we describe a set of quantitative real-time PCR assays and a global expression profile of cystatin genes in normal mouse tissues. Benefiting from our collection of DelES embryonic stem cell clones harboring large chromosomal deletions (to be reported elsewhere), we selected a clone in which a 95-kb region of chromosome 16 is missing (Del16qB3Δ/+). In this particular clone, 2 cystatin genes, namely Csta and Stfa2l1 are absent along with 2 other genes (Fam162a, Ccdc58) and associated intergenic regions. From this line, we established a new homozygous mutant mouse model (Del16qB3Δ/16qB3Δ) to assess the in vivo biological functions of the 2 deleted cystatins. Stfa2l1 gene expression is high in wild-type fetal liver, bone marrow, and spleen, while Csta is ubiquitously expressed. Homozygous Del16qB3Δ/16qB3Δ animals are phenotypically normal, fertile, and not overtly susceptible to spontaneous or irradiation-induced tumor formation. The hematopoietic stem and progenitor cell activity in these mutant mice are also normal. Interestingly, quantitative real-time PCR expression profiling reveals a marked increase in the expression levels of Stfa2l1/Csta phylogenetically-related genes (Stfa1, Stfa2, and Stfa3) in Del16qB3Δ/16qB3Δ hematopoietic tissues, suggesting that these candidate genes might be contributing to compensatory mechanisms. Overall, this study presents an optimized approach to globally monitor cystatin gene expression as well as a new mouse model deficient in Stfa2l1/Csta genes, expanding the available tools to dissect cystatin roles under normal and pathological conditions

    Modelling the monthly abundance of Culicoides biting midges in nine European countries using Random Forests machine learning

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    Background: Culicoides biting midges transmit viruses resulting in disease in ruminants and equids such as bluetongue, Schmallenberg disease and African horse sickness. In the past decades, these diseases have led to important economic losses for farmers in Europe. Vector abundance is a key factor in determining the risk of vector-borne disease spread and it is, therefore, important to predict the abundance of Culicoides species involved in the transmission of these pathogens. The objectives of this study were to model and map the monthly abundances of Culicoides in Europe. Methods: We obtained entomological data from 904 farms in nine European countries (Spain, France, Germany, Switzerland, Austria, Poland, Denmark, Sweden and Norway) from 2007 to 2013. Using environmental and climatic predictors from satellite imagery and the machine learning technique Random Forests, we predicted the monthly average abundance at a 1 km2 resolution. We used independent test sets for validation and to assess model performance. Results: The predictive power of the resulting models varied according to month and the Culicoides species/ensembles predicted. Model performance was lower for winter months. Performance was higher for the Obsoletus ensemble, followed by the Pulicaris ensemble, while the model for Culicoides imicola showed a poor performance. Distribution and abundance patterns corresponded well with the known distributions in Europe. The Random Forests model approach was able to distinguish differences in abundance between countries but was not able to predict vector abundance at individual farm level. Conclusions: The models and maps presented here represent an initial attempt to capture large scale geographical and temporal variations in Culicoides abundance. The models are a first step towards producing abundance inputs for R0 modelling of Culicoides-borne infections at a continental scale

    A genome-wide association study of aging

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    AbstractHuman longevity and healthy aging show moderate heritability (20%–50%). We conducted a meta-analysis of genome-wide association studies from 9 studies from the Cohorts for Heart and Aging Research in Genomic Epidemiology Consortium for 2 outcomes: (1) all-cause mortality, and (2) survival free of major disease or death. No single nucleotide polymorphism (SNP) was a genome-wide significant predictor of either outcome (p < 5 × 10−8). We found 14 independent SNPs that predicted risk of death, and 8 SNPs that predicted event-free survival (p < 10−5). These SNPs are in or near genes that are highly expressed in the brain (HECW2, HIP1, BIN2, GRIA1), genes involved in neural development and function (KCNQ4, LMO4, GRIA1, NETO1) and autophagy (ATG4C), and genes that are associated with risk of various diseases including cancer and Alzheimer's disease. In addition to considerable overlap between the traits, pathway and network analysis corroborated these findings. These findings indicate that variation in genes involved in neurological processes may be an important factor in regulating aging free of major disease and achieving longevity
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