The long-term agronomic performance of organic stockless rotations

This report was presented at the UK Organic Research 2002 Conference. Two long-term experiments were established with the aim of evaluating the agronomic and economic performance of organic stockless rotations. In total, four different rotations were evaluated at two sites in the south (Elm Farm Research Centre) and east (ADAS Terrington) of England. All of the rotations included either a one or two-year red clover green manure crop to provide nitrogen for subsequent crops and it was found that this was sufficient to support three or four years of arable cropping. Over a period of eleven years at EFRC and five years at ADAS Terrington, there was no evidence of a decline in crop yield, although there were significant year-to-year variations. Crop yields were generally equivalent to or greater than average organic yields. Levels of soil available P and K was maintained at both sites at non-limiting levels. Pest and diseases were not problematic, but perennial weeds posed the most significant problem

A p21-Activated Kinase Is Required for Conidial Germination in Penicillium marneffei

Asexual spores (conidia) are the infectious propagules of many pathogenic fungi, and the capacity to sense the host environment and trigger conidial germination is a key pathogenicity determinant. Germination of conidia requires the de novo establishment of a polarised growth axis and consequent germ tube extension. The molecular mechanisms that control polarisation during germination are poorly understood. In the dimorphic human pathogenic fungus Penicillium marneffei, conidia germinate to produce one of two cell types that have very different fates in response to an environmental cue. At 25 °C, conidia germinate to produce the saprophytic cell type, septate, multinucleate hyphae that have the capacity to undergo asexual development. At 37 °C, conidia germinate to produce the pathogenic cell type, arthroconidiating hyphae that liberate uninucleate yeast cells. This study shows that the p21-activated kinase pakA is an essential component of the polarity establishment machinery during conidial germination and polarised growth of yeast cells at 37 °C but is not required for germination or polarised growth at 25 °C. Analysis shows that the heterotrimeric G protein α subunit GasC and the CDC42 orthologue CflA lie upstream of PakA for germination at both temperatures, while the Ras orthologue RasA only functions at 25 °C. These findings suggest that although some proteins that regulate the establishment of polarised growth in budding yeast are conserved in filamentous fungi, the circuitry and downstream effectors are differentially regulated to give rise to distinct cell types

General practice ethnicity data: evaluation of a tool

INTRODUCTION: There is evidence that the collection of ethnicity data in New Zealand primary care is variable and that data recording in practices does not always align with the procedures outlined in the Ethnicity Data Protocols for the Health and Disability Sector. In 2010, The Ministry of Health funded the development of a tool to audit the collection of ethnicity data in primary care. The aim of this study was to pilot the Ethnicity Data Audit Tool (EAT) in general practice. The goal was to evaluate the tool and identify recommendations for its improvement. METHODS: Eight general practices in the Waitemata District Health Board region participated in the EAT pilot. Feedback about the pilot process was gathered by questionnaires and interviews, to gain an understanding of practices’ experiences in using the tool. Questionnaire and interview data were analysed using a simple analytical framework and a general inductive method. FINDINGS: General practice receptionists, practice managers and general practitioners participated in the pilot. Participants found the pilot process challenging but enlightening. The majority felt that the EAT was a useful quality improvement tool for handling patient ethnicity data. Larger practices were the most positive about the tool. CONCLUSION: The findings suggest that, with minor improvements to the toolkit, the EAT has the potential to lead to significant improvements in the quality of ethnicity data collection and recording in New Zealand general practices. Other system-level factors also need to be addressed

Hypercrosslinked materials

This chapter describes the chemistry of hypercrosslinked materials, and presents a description of their synthesis, defining physico-chemical features and their most important applications. The synthesis section will examine the different monomers, precursor polymers, reagents and synthetic strategies used to prepare hypercrosslinked materials. Each synthesis section also details the chemical and morphological properties of the hypercrosslinked materials and the main field of application

Hypercrosslinked materials : preparation, characterisation and applications

This review article provides an overview of hypercrosslinking technology. In particular, it covers the preparation and characterisation of hypercrosslinked materials and their applications. The synthesis section examines the different monomers, precursor polymers and reagents used to prepare hypercrosslinked materials, but also the different synthetic approaches disclosed in the literature. The various chemical modification reactions relevant to this area are also reviewed. Several examples of applications for hypercrosslinked materials are described; these applications are grouped into thematic areas such as chromatography, gas storage and the trapping of organic contaminants

Insertion site preference of Mu, Tn5, and Tn7 transposons

<p>Abstract</p> <p>Background</p> <p>Transposons, segments of DNA that can mobilize to other locations in a genome, are often used for insertion mutagenesis or to generate priming sites for sequencing of large DNA molecules. For both of these uses, a transposon with minimal insertion bias is desired to allow complete coverage with minimal oversampling.</p> <p>Findings</p> <p>Three transposons, Mu, Tn5, and Tn7, were used to generate insertions in the same set of fosmids containing <it>Candida glabrata </it>genomic DNA. Tn7 demonstrates markedly less insertion bias than either Mu or Tn5, with both Mu and Tn5 biased toward sequences containing guanosine (G) and cytidine (C). This preference of Mu and Tn5 yields less uniform spacing of insertions than for Tn7, in the adenosine (A) and thymidine (T) rich genome of <it>C. glabrata </it>(39% GC).</p> <p>Conclusions</p> <p>In light of its more uniform distribution of insertions, Tn7 should be considered for applications in which insertion bias is deleterious.</p

Many Globally Isolated AD Hybrid Strains of Cryptococcus neoformans Originated in Africa

Interspecific and intervarietal hybridization may contribute to the biological diversity of fungal populations. Cryptococcus neoformans is a pathogenic yeast and the most common fungal cause of meningitis in patients with AIDS. Most patients are infected with either of the two varieties of C. neoformans, designated as serotype A (C. neoformans var. grubii) or serotype D (C. neoformans var. neoformans). In addition, serotype AD strains, which are hybrids of these two varieties, are commonly isolated from clinical and environmental samples. While most isolates of serotype A and serotype D are haploid, AD strains are diploid or aneuploid, and contain two sets of chromosomes and two mating type alleles, MATa and MATα, one from each of the serotypes. The global population of serotype A is dominated by isolates with the MATα mating type (Aα); however, about half of the globally analyzed AD strains possess the extremely rare serotype A MATa allele (Aa). We previously described an unusual population of serotype A in Botswana, in which 25% of the strains contain the rare MATa allele. Here we utilized two methods, phylogenetic analysis of three genes and genotyping by scoring amplified fragment length polymorphisms, and discovered that AD hybrid strains possessing the rare serotype A MATa allele (genotype AaDα) cluster with isolates of serotype A from Botswana, whereas AD hybrids that possess the MATα serotype A allele (AαDa and AαDα) cluster with cosmopolitan isolates of serotype A. We also determined that AD hybrid strains are more resistant to UV irradiation than haploid serotype A strains from Botswana. These findings support two hypotheses: (i) AaDα strains originated in sub-Saharan Africa from a cross between strains of serotypes A and D; and (ii) this fusion produced hybrid strains with increased fitness, enabling the Botswanan serotype A MATa genome, which is otherwise geographically restricted, to survive, emigrate, and propagate throughout the world

Continuous macroscopic limit of a discrete stochastic model for interaction of living cells

In the development of multiscale biological models it is crucial to establish a connection between discrete microscopic or mesoscopic stochastic models and macroscopic continuous descriptions based on cellular density. In this paper a continuous limit of a two-dimensional Cellular Potts Model (CPM) with excluded volume is derived, describing cells moving in a medium and reacting to each other through both direct contact and long range chemotaxis. The continuous macroscopic model is obtained as a Fokker-Planck equation describing evolution of the cell probability density function. All coefficients of the general macroscopic model are derived from parameters of the CPM and a very good agreement is demonstrated between CPM Monte Carlo simulations and numerical solution of the macroscopic model. It is also shown that in the absence of contact cell-cell interactions, the obtained model reduces to the classical macroscopic Keller-Segel model. General multiscale approach is demonstrated by simulating spongy bone formation from loosely packed mesenchyme via the intramembranous route suggesting that self-organizing physical mechanisms can account for this developmental process.Comment: 4 pages, 3 figure

Fermi Surface as the Driving Mechanism for Helical Antiferromagnetic Ordering in Gd-Y Alloys

The first direct experimental evidence for the Fermi surface (FS) driving the helical antiferromagnetic ordering in a gadolinium-yttrium alloy is reported. The presence of a FS sheet capable of nesting is revealed, and the nesting vector associated with the sheet is found to be in excellent agreement with the periodicity of the helical ordering.Comment: 4 pages, 4 figure