Determinants of DNA yield and purity collected with buccal cell samples

Buccal cells are an important source of DNA in epidemiological studies, but little is known about factors that influence amount and purity of DNA. We assessed these factors in a self-administered buccal cell collection procedure, obtained with three cotton swabs. In 2,451 patients DNA yield and in 1,033 patients DNA purity was assessed. Total DNA yield ranged from 0.08 to 1078.0 μg (median 54.3 μg; mean 82.2 μg ± SD 92.6). The median UV 260:280 ratio, was 1.95. Samples from men yielded significantly more DNA (median 58.7 μg) than those from women (median 44.2 μg). Diuretic drug users had significantly lower purity (median 1.92) compared to other antihypertensive drug users (1.95). One technician obtained significantly lower DNA yields. Older age was associated with lower DNA purity. In conclusion, DNA yield from buccal swabs was higher in men and DNA purity was associated with age and the use of diuretics

De relatie tussen bosontwikkeling op de Zuidoost Veluwe en de aantallen edelherten, damherten, reeën, wilde zwijnen, runderen en paarden.

De eigenaren van de Zuidoost Veluwe verschillen in hun doelstelling t.a.v. het beheer van bos en natuur. Daarmee verschilt ook hun houding t.a.v. de aantallen paarden, runderen, damherten, wilde zwijnen en edelherten. Het rapport biedt inzicht in de effecten van deze grote grazers op de bosontwikkeling. Er wordt een relatie gelegd met hoofddoelstelling van de terreinbeheerder (natuur voor Natuurmonumenten; houtproductie voor Stichting Twickel en Landgoed Middachten). Een dynamisch bosontwikkelingsmodel (FORSPACE) werd gehanteerd in relatie tot hoefdieren en bosontwikkelin

Circulation of four Anaplasma phagocytophilum ecotypes in Europe

Background: Anaplasma phagocytophilum is the etiological agent of granulocytic anaplasmosis in humans and animals. Wild animals and ticks play key roles in the enzootic cycles of the pathogen. Potential ecotypes of A. phagocytophilum have been characterized genetically, but their host range, zoonotic potential and transmission dynamics has only incompletely been resolved. Methods. The presence of A. phagocytophilum DNA was determined in more than 6000 ixodid ticks collected from the vegetation and wildlife, in 289 tissue samples from wild and domestic animals, and 69 keds collected from deer, originating from various geographic locations in The Netherlands and Belgium. From the qPCR-positive lysates, a fragment of the groEL-gene was amplified and sequenced. Additional groEL sequences from ticks and animals from Europe were obtained from GenBank, and sequences from human cases were obtained through literature searches. Statistical analyses were performed to identify A. phagocytophilum ecotypes, to assess their host range and their zoonotic potential. The population dynamics of A. phagocytophilum ecotypes was investigated using population genetic analyses. Results: DNA of A. phagocytophilum was present in all stages of questing and feeding Ixodes ricinus, feeding I. hexagonus, I. frontalis, I. trianguliceps, and deer keds, but was absent in questing I. arboricola and Dermacentor reticulatus. DNA of A. phagocytophilum was present in feeding ticks and tissues from many vertebrates, including roe deer, mouflon, red foxes, wild boar, sheep and hedgehogs but was rarely found in rodents and birds and was absent in badgers and lizards. Four geographically dispersed A. phagocytophilum ecotypes were identified, that had significantly different host ranges. All sequences from human cases belonged to only one of these ecotypes. Based on population genetic parameters, the potentially zoonotic ecotype showed significant expansion. Conclusion: Four ecotypes of A. phagocytophilum with differential enzootic cycles were identified. So far, all human cases clustered in only one of these ecotypes. The zoonotic ecotype has the broadest range of wildlife hosts. The expansion of the zoonotic A. phagocytophilum ecotype indicates a recent increase of the acarological risk of exposure of humans and animals

Landscape forming processes and diversity of forested landscapes : description and application of the model FORSPACE

In the project "Landschapsvormende processen en biodiversiteit" ("Landscape forming processes and bioversity") the spatial interactions between autonomous development of a vegetation and landscape forming processes were investigated and their implications for (bio)diversity at the landscape level were evaluated. For this purpose the model FORSPACE was developed which is a spatial explicit process model that describes vegetation dynamics and the impacts of landscape forming processes. In this study emphasis was paid to the effects of grazing by large herbivores and fire on the vegetation. Two approaches to analyse diversity at the landscape scale were developed: 1) a spatial analysis evaluating the time-evolution of dominant vegetation types, and 2) a metapopulation approach that describes the population dynamics of indicator species at the landscape scale depending on the availability of habitat. This report focuses on the methodological aspects of the study and thus acts as a reference for future applied studies. The model structure is described in detail, as well as the approach of spatial analysis and of the metapopulation dynamics of an indicator species. Much emphasis is paid on the validation of the driving processes for trees, herbs and grasses by evaluating controlled simulation experiments. In a case-study on the 200 ha of the Imbos, an area in the centre of the Netherlands, the impacts of grazing by herbivores and its interaction with different fire frequencies were evaluated

The Generation R Study: design and cohort update 2010

The Generation R Study is a population-based prospective cohort study from fetal life until young adulthood. The study is designed to identify early environmental and genetic causes of normal and abnormal growth, development and health during fetal life, childhood and adulthood. The study focuses on four primary areas of research: (1) growth and physical development; (2) behavioural and cognitive development; (3) diseases in childhood; and (4) health and healthcare for pregnant women and children. In total, 9,778 mothers with a delivery date from April 2002 until January 2006 were enrolled in the study. General follow-up rates until the age of 4 years exceed 75%. Data collection in mothers, fathers and preschool children included questionnaires, detailed physical and ultrasound examinations, behavioural observations, and biological samples. A genome wide association screen is available in the participating children. Regular detailed hands on assessment are performed from the age of 5 years onwards. Eventually, results forthcoming from the Generation R Study have to contribute to the development of strategies for optimizing health and healthcare for pregnant women and children