With a Senior Investigator in the Axon Guidance and Neural Connectivity Section, NINDS, and with members of the Biomedical Imaging Research Services Section of the Office of Intramural Research, CIT, we are studying the mechanisms that guide neurons axons to their ultimate targets. In particular, we are examining a series of experiments involve the growth of a neuron in the wing disc extracted from Drosophlia larvae in which we monitor the dynamics of a cytoskelotal protein, actin, at sub-micrometer resolution for periods up to an 1.5 hours in the growing axon as it senses it way through the muscle tissue of the disc. We are also examining the effects on the axon growth dyanmics by mutations in a kinase that modulates the actin activity. An article is in preparation for submission to peer review. With an principal investigator in Section on Neuronal Connectivity, NICHD, and with members of the Biomedical Imaging Research Services Section of the Division of Computational Bioscience, CIT, we are working on statistical and topological analysis of retinal neurons growth in Drosophila. The dendritic trees of these neurons have a length and directional biases that is very dependent on their local environment. In addition, we have found that dendritic branching and termination are not simple Poisson processes. We prepare and examine flies with mutant genes for neurotrophic factors in order to determine what guides the direction and length of dendritic tree growth. We are also preparing a open source set of software tools that we have found useful. A peer-reviewd review article describing the experimental techiques was published in 2017. With a principal investigator and staff clinician in Section on Clinical Psychoneuroendocrinology and Neuropsychopharmacology, National Institute of Alcohol Abuse and Alcoholism, and with a staff scientist in the Mathematical and Statistical Laboratory, Office of Intramural Research, CIT, we are trying to determine the correlates for treatment seeking in a population of alcohol abusers. This studying is considering environmental, physiological, and genomic factors. A article for peer-review is in preparation. With a Senior Investigator in the Section on Eukaryotic Transposable Elements, NICHD, we are studying the mechanisms and rate by which retrotransposons insert themselves into eukaryote chromosomes. A library of specially engineered nucleotide sequences are attached to the retrotransposons, allowing for a statistical analysis of genome patterns around hot spots, positions on chromosomes where insertion occur at a high rate. With a consortium of investigators from the (1) Computational Bioscience and Engineering Laboratory, Office of Intramural Research, CIT, and (2) Biomedical Engineering and Physical Science Shared Resource, National Institute of Biomedical Imaging and Bioengineering, we modeled the thermal and fluid transport that occur in the operation of activated expression microdissection. This is a method of extracting large number of cells in which a normally expressed protein is stained with a light-absorbing dye. At exposure to light, the heated stain melts a polymer film that binds to tissue, allowing for pickup of cellular components. The engineering development is nearing the point where the method can be utilized in pathology laboratories, and the NIH Office of Technology Transfer is in negotiations with potential commercial developers. Two current foci in this work are (1) charting the dosimetry as a function of light spectrum and tissue type, and (2) understaning the physics of the fluiding binding to the tissue. Both items (1) and (2) are needed together to create a stable dosimetry protocol.
