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Articles by Daniel N. Cox in JoVE

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Выделение и очистка Drosophila Периферийные Нейроны магнитными бисера Сортировка


JoVE 1599 12/01/2009

1Department of Molecular and Microbiology, George Mason University, 2Krasnow Institute for Advanced Study, George Mason University

В этом видео-работе предлагается метод выделения и очистки

Other articles by Daniel N. Cox on PubMed

Bazooka is a Permissive Factor for the Invasive Behavior of Discs Large Tumor Cells in Drosophila Ovarian Follicular Epithelia

Drosophila Bazooka and atypical protein kinase C are essential for epithelial polarity and adhesion. We show here that wild-type bazooka function is required during cell invasion of epithelial follicle cells mutant for the tumor suppressor discs large. Clonal studies indicate that follicle cell Bazooka acts as a permissive factor during cell invasion, possibly by stabilizing adhesion between the invading somatic cells and their substratum, the germline cells. Genetic epistasis experiments demonstrate that bazooka acts downstream of discs large in tumor cell invasion. In contrast, during the migration of border cells, Bazooka function is dispensable for cell invasion and motility, but rather is required cell-autonomously in mediating cell adhesion within the migrating border cell cluster. Taken together, these studies reveal Bazooka functions distinctly in different types of invasive behaviors of epithelial follicle cells, potentially by regulating adhesion between follicle cells or between follicle cells and their germline substratum.

Control of Dendrite Arborization by an Ig Family Member, Dendrite Arborization and Synapse Maturation 1 (Dasm1)

Development of both dendrites and axons is important for the formation of neuronal circuits, because dendrites receive information and the axon is responsible for sending signals. In the past decade, extensive studies have revealed many molecules underlying axonal outgrowth and pathfinding. In contrast, much less is known about the molecular mechanisms that control dendrite development. Here we report the identification of an evolutionarily conserved Ig superfamily member, dendrite arborization and synapse maturation 1 (Dasm1), which plays a critical role in dendrite development. Dasm1 contains five Ig domains and two fibronectin III domains in the extracellular N terminus, a single transmembrane domain, and an intracellular C-terminal tail with a type I PDZ domain binding motif at the end. It is highly expressed in the brain and localized at the dendrites. Suppression of Dasm1 expression in hippocampal neurons via RNA interference or expression of Dasm1 without its cytoplasmic tail specifically impairs dendrite, but not axon, outgrowth. Together with its orthologues in other species, Dasm1 defines a family of molecules likely involved specifically in dendrite arborization.

Regulatory Relationship Among Piwi, Pumilio, and Bag-of-marbles in Drosophila Germline Stem Cell Self-renewal and Differentiation

The transition from a Drosophila ovarian germline stem cell (GSC) to its differentiated daughter cell, the cystoblast, is controlled by both niche signals and intrinsic factors. piwi and pumilio (pum) are essential for GSC self-renewal, whereas bag-of-marbles (bam) is required for cystoblast differentiation. We demonstrate that Piwi and Bam proteins are expressed independently of each other in reciprocal patterns in GSCs and cystoblasts. However, overexpression of either one antagonizes the other in these cells. Furthermore, piwi;bam double mutants phenocopy the bam mutant. This epistasis reflects the niche signaling function of piwi because depleting piwi from niche cells in bam mutant ovaries also phenocopies bam mutants. Thus, bam is epistatic to niche Piwi, but not germline Piwi function. Despite this, bam- ovaries lacking germline Piwi contain approximately 4-fold fewer germ cells than bam- ovaries, consistent with the role of germline Piwi in promoting GSC mitosis by 4-fold. Finally, pum is epistatic to bam, indicating that niche Piwi does not regulate Bam-C through Pum. We propose that niche Piwi maintains GSCs by repressing bam expression in GSCs, which consequently prevents Bam from downregulating Pum/Nos function in repressing the translation of differentiation genes and germline Piwi function in promoting germ cell division.

The Role of PIWI and the MiRNA Machinery in Drosophila Germline Determination

The germ plasm has long been demonstrated to be necessary and sufficient for germline determination, with translational regulation playing a key role in the process. Beyond this, little is known about molecular activities underlying germline determination.

Genomic Phenotype of Non-cultured Pulmonary Fibroblasts in Idiopathic Pulmonary Fibrosis

Activated fibroblasts are the central effector cells of the progressive fibrotic process in idiopathic pulmonary fibrosis (IPF). Characterizing the genomic phenotype of isolated fibroblasts is essential to understanding IPF pathogenesis. Comparing the genomic phenotype of non-cultured pulmonary fibroblasts from advanced IPF patients' and normal lungs revealed novel genes, biological processes and concomitant pathways previously unreported in IPF fibroblasts. We demonstrate altered expression in proteasomal constituents, ubiquitination-mediators, Wnt, apoptosis and vitamin metabolic pathways and cell cycle regulators, suggestive of loss of cellular homeostasis. Specifically, FBXO32, CXCL14, BDKRB1 and NMNAT1 were up-regulated, while RARA and CDKN2D were down-regulated. Paradoxically, pro-apoptotic inducers TNFSF10, BAX and CASP6 were also found to be increased. This comprehensive description of altered gene expression in isolated IPF fibroblasts underscores the complex biological processes characteristic of IPF and may provide a foundation for future research into this devastating disease.

Turtle Functions Downstream of Cut in Differentially Regulating Class Specific Dendrite Morphogenesis in Drosophila

Dendritic morphology largely determines patterns of synaptic connectivity and electrochemical properties of a neuron. Neurons display a myriad diversity of dendritic geometries which serve as a basis for functional classification. Several types of molecules have recently been identified which regulate dendrite morphology by acting at the levels of transcriptional regulation, direct interactions with the cytoskeleton and organelles, and cell surface interactions. Although there has been substantial progress in understanding the molecular mechanisms of dendrite morphogenesis, the specification of class-specific dendritic arbors remains largely unexplained. Furthermore, the presence of numerous regulators suggests that they must work in concert. However, presently, few genetic pathways regulating dendrite development have been defined.

Growing Pains: Development of the Larval Nocifensive Response in Drosophila

The ability to perceive and avoid harmful substances or stimuli is key to an organism's survival. The neuronal cognate of the perception of pain is known as nociception, and the reflexive motion to avoid pain is termed the nocifensive response. As the nocifensive response is an ancient and evolutionarily conserved behavioral response to nociceptive stimuli, it is amenable to study in relatively simple and genetically tractable model systems such as Drosophila. Recent studies have taken advantage of the useful properties of Drosophila larvae to begin elucidating the neuronal connectivity and molecular machinery underlying the nocifensive response. However, these studies have primarily utilized the third-instar larval stage, and many mutations that potentially influence nociception survive only until earlier larval stages. Here we characterize the nocifensive responses of Drosophila throughout larval development and find dramatic changes in the nature of the behavior. Notably, we find that prior to the third instar, larvae are unable to perform the characteristic "corkscrew-like roll" behavior. Also, we identify an avoidance behavior consistent with a nocifensive response that is present immediately after larval hatching, representing a paradigm that may be useful in examining mutations with an early lethal phenotype.

Adult Neural Stem Cells: Isolation and Propagation

Individualized therapy using adult stem cells constitutes a revolutionary vision for molecular medicine of the future. The field of stem cell biology has accelerated dramatically such that it now appears feasible to treat an individual patient's disease with native or modified stem cells collected from the same patient. Neurodegenerative disease is a high-priority goal for stem cell therapy due to the tremendous clinical urgency to reduce the worldwide suffering associated with this class of diseases. This chapter focuses on adult neural stem cells as a prototype for the general field of adult stem cell therapy. Studies of the origin and function of neural stem cells reveals that the adult brain can generate new neurons. This finding provides the rationale for the therapeutic application of adult neural stem cells to treat neuronal damage or loss. Experimental progress in treating Parkinson's disease is discussed in some detail as an example of one of the most promising areas for adult neural stem cell therapy. Methods for neural stem cell isolation and propagation are included.

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