Targeted mutagenesis by homologous recombination in D. melanogaster

Journal ArticleWe used a recently developed method to produce mutant alleles of five endogenous Drosophila genes, including the homolog of the p53 tumor suppressor. Transgenic expression of the FLP site-specific recombinase and the I-SceI endonuclease generates extrachromosomal linear DNA molecules in vivo

A study of laser plasmas as X-ray sources in the 1-10 keV spectral region

An experimental investigation on X-ray emission from laser-produced plasmas is presented and the properties of such an emission of interest for application purposes are examined. Plasmas were generated by focusing 1 μm, 3 ns Nd laser pulses onto Al and Cu targets at an intensity of 1013 W/cm2. The temporal evolution of the emission and its spectral features were investigated by using an X-ray streak-camera and an X-ray photodiode. In the case of Cu targets, the analysis of the emission showed two spectral components. The main component was centered at ≈ 1.2 keV and a minor component, whose intensity was measured to be 10-3 of the previous component, was observed at ≈7 keV. The X-ray conversion efficiency, in the investigated spectral region, was measured to be 1% for Cu targets and 0.3% for Al targets

Guidance of neuronal growth cones in the grasshopper embryo. III. Recognition of specific glial pathways

Journal ArticleIn the previous 2 papers, we focused on the selective affinities that growth cones display for specific axonal pathways. Little is known, however, about how this orthogonal scaffold of axonal pathways in the CNS is established in the first place, and what, if any, role glia might play in these events

Characterization and cloning of fasciclin I and fasciclin II glycoproteins in the grasshopper

Monoclonal antibodies were previously used to identify two glycoproteins, called fasciclin I and II (70 and 95 kDa, respectively), which are expressed on different subsets of axon fascicles in the grasshopper (Schistocerca americana) embryo. Here the monoclonal antibodies were used to purify these two membrane-associated glycoproteins for further characterization. Fasciclin II appears to be an integral membrane protein, where fasciclin I is an extrinsic membrane protein. The amino acid sequences of the amino terminus and fragments of both proteins were determined. Using synthetic oligonucleotide probes and antibody screening, we isolated genomic and cDNA clones. Partial DNA sequences of these clones indicate that they encode fasciclins I and II

Worm Phenotype Ontology: Integrating phenotype data within and beyond the C. elegans community

Background: Caenorhabditis elegans gene-based phenotype information dates back to the 1970’s, beginning with Sydney Brenner and the characterization of behavioral and morphological mutant alleles via classical genetics in order to understand nervous system function. Since then C. elegans has become an important genetic model system for the study of basic biological and biomedical principles, largely through the use of phenotype analysis. Because of the growth of C. elegans as a genetically tractable model organism and the development of large-scale analyses, there has been a significant increase of phenotype data that needs to be managed and made accessible to the research community. To do so, a standardized vocabulary is necessary to integrate phenotype data from diverse sources, permit integration with other data types and render the data in a computable form. Results: We describe a hierarchically structured, controlled vocabulary of terms that can be used to standardize phenotype descriptions in C. elegans, namely the Worm Phenotype Ontology (WPO). The WPO is currently comprised of 1,880 phenotype terms, 74% of which have been used in the annotation of phenotypes associated with greater than 18,000 C. elegans genes. The scope of the WPO is not exclusively limited to C. elegans biology, rather it is devised to also incorporate phenotypes observed in related nematode species. We have enriched the value of the WPO by integrating it with other ontologies, thereby increasing the accessibility of worm phenotypes to non-nematode biologists. We are actively developing the WPO to continue to fulfill the evolving needs of the scientific community and hope to engage researchers in this crucial endeavor. Conclusions: We provide a phenotype ontology (WPO) that will help to facilitate data retrieval, and cross-species comparisons within the nematode community. In the larger scientific community, the WPO will permit data integration, and interoperability across the different Model Organism Databases (MODs) and other biological databases. This standardized phenotype ontology will therefore allow for more complex data queries and enhance bioinformatic analyses

Dyslexia-friendly schools and parent partnership: inclusion and home-school relationships

This is a postprint of an article whose final and definitive form has been published in the European Journal of Special Needs Education© 2005 Copyright Taylor & Francis; European Journal of Special Needs Education is available online at http://www.informaworld.comThis paper summarizes an action research project in five local areas in the south-west of England which aimed to support parents of children with dyslexic difficulties who were experiencing problems in obtaining appropriate provision in mainstream schools. It was based on the importance of effective parental partnership and quality inclusive practice for children having dyslexic difficulties. A development officer worked over two years in the five participating LEAs that were selected to represent a range of professional practice with a mix of urban and rural populations. As part of the evaluation, the authors also examined longitudinally the educational experiences of a sample of parents. The paper includes a conceptual framework of parental agency in this field in terms of knowledge, identity and parental strategies, and the conditions under which parents escalate their strategies to secure appropriate provision for their children. The support provided by the development officer is analysed in terms of the kinds of support requests received, the kinds of support offered and qualitative evidence of the impact of this support. This research is theorized in terms of current ideas about parent-partnership and theories about parent-teacher relations in terms of the diversity of parents. It highlights the significance of thinking about inclusive schooling and parent-school relations in terms of the interconnections between general systems for all, for those with special educational needs and those with specific difficulties. The policy and practice implications are interpreted in terms of the importance of a system of extended professionalism, which is inclusive of parents with learning difficulties and disabilities.The research project this paper summarises was funded by the British Dyslexia Association (BDA) and the Buttle Trust

Non-negative data-driven mapping of structural connections with application to the neonatal brain

Mapping connections in the neonatal brain can provide insight into the crucial early stages of neurodevelopment that shape brain organisation and lay the foundations for cognition and behaviour. Diffusion MRI and tractography provide unique opportunities for such explorations, through estimation of white matter bundles and brain connectivity. Atlas-based tractography protocols, i.e. a priori defined sets of masks and logical operations in a template space, have been commonly used in the adult brain to drive such explorations. However, rapid growth and maturation of the brain during early development make it challenging to ensure correspondence and validity of such atlas-based tractography approaches in the developing brain. An alternative can be provided by data-driven methods, which do not depend on predefined regions of interest. Here, we develop a novel data-driven framework to extract white matter bundles and their associated grey matter networks from neonatal tractography data, based on non-negative matrix factorisation that is inherently suited to the non-negative nature of structural connectivity data. We also develop a non-negative dual regression framework to map group-level components to individual subjects. Using in-silico simulations, we evaluate the accuracy of our approach in extracting connectivity components and compare with an alternative data-driven method, independent component analysis. We apply non-negative matrix factorisation to whole-brain connectivity obtained from publicly available datasets from the Developing Human Connectome Project, yielding grey matter components and their corresponding white matter bundles. We assess the validity and interpretability of these components against traditional tractography results and grey matter networks obtained from resting-state fMRI in the same subjects. We subsequently use them to generate a parcellation of the neonatal cortex using data from 323 new-born babies and we assess the robustness and reproducibility of this connectivity-driven parcellation