In vivo imaging of retrogradely transported synaptic vesicle proteins in Caenorhabditis elegans neurons

Women in Neuroscience: Four Women’s Contributions to Science and Society

There has been increased cognizance of gender inequity and the importance of an inclusive and diverse approach to scientific research in recent years. However, the innovative work of women scientists is still undervalued based on reports of fewer women in leadership positions, limited citations of research spearheaded by women, reduced federal grant awards, and lack of recognition. Women have been involved in trailblazing work that paved the way for contemporary scientific inquiry. The strides made in current neuroscience include contributions from women who deserve more recognition. In this review, we discuss the work of four women whose groundbreaking scientific work has made ineffaceable marks in the neuroscience field. These women are pioneers of research and innovators and, in addition, contribute to positive change that bolsters the academic community and society. This article celebrates these women scientists, their substantial impacts in neuroscience, and the positive influence of their work on advancing society and culture.

Tissue-specific targeting of DNA nanodevices in a multicellular living organism

Nucleic acid nanodevices present great potential as agents for logic-based therapeutic intervention as well as in basic biology. Often, however, the disease targets that need corrective action are localized in specific organs, and thus realizing the full potential of DNA nanodevices also requires ways to target them to specific cell types in vivo. Here, we show that by exploiting either endogenous or synthetic receptor-ligand interactions and leveraging the biological barriers presented by the organism, we can target extraneously introduced DNA nanodevices to specific cell types in Caenorhabditis elegans, with subcellular precision. The amenability of DNA nanostructures to tissue-specific targeting in vivo significantly expands their utility in biomedical applications and discovery biology.

Molecular mechanisms governing axonal transport: a C. elegans perspective

Axonal transport is integral for maintaining neuronal form and function, and defects in axonal transport have been correlated with several neurological diseases, making it a subject of extensive research over the past several years. The anterograde and retrograde transport machineries are crucial for the delivery and distribution of several cytoskeletal elements, growth factors, organelles and other synaptic cargo. Molecular motors and the neuronal cytoskeleton function as effectors for multiple neuronal processes such as axon outgrowth and synapse formation. This review examines the molecular mechanisms governing axonal transport, specifically highlighting the contribution of studies conducted in C. elegans, which has proved to be a tractable model system in which to identify both novel and conserved regulatory mechanisms of axonal transport.

Isolation of synaptic vesicles from genetically engineered cultured neurons

BACKGROUND

Synaptic vesicles (SVs) are an integral part of the neurotransmission machinery, and isolation of SVs from their host neuron is necessary to reveal their most fundamental biochemical and functional properties in in vitro assays. Isolated SVs from neurons that have been genetically engineered, e.g. to introduce genetically encoded indicators, are not readily available but would permit new insights into SV structure and function. Furthermore, it is unclear if cultured neurons can provide sufficient starting material for SV isolation procedures.

NEW METHOD

Here, we demonstrate an efficient ex vivo procedure to obtain functional SVs from cultured rat cortical neurons after genetic engineering with a lentivirus.

RESULTS

We show that ∼10⁸ plated cortical neurons allow isolation of suitable SV amounts for functional analysis and imaging. We found that SVs isolated from cultured neurons have neurotransmitter uptake comparable to that of SVs isolated from intact cortex. Using total internal reflection fluorescence (TIRF) microscopy, we visualized an exogenous SV-targeted marker protein and demonstrated the high efficiency of SV modification.

COMPARISON WITH EXISTING METHODS

Obtaining SVs from genetically engineered neurons currently generally requires the availability of transgenic animals, which is constrained by technical (e.g. cost and time) and biological (e.g. developmental defects and lethality) limitations.

CONCLUSIONS

These results demonstrate the modification and isolation of functional SVs using cultured neurons and viral transduction. The ability to readily obtain SVs from genetically engineered neurons will permit linking in situ studies to in vitro experiments in a variety of genetic contexts.

Microfluidic devices for imaging trafficking events in vivo using genetic model organisms

Miniature devices are powerful new tools that can be used to address multiple questions in biology especially in investigating an individual cell or organism. The primary step forward has been the ease of soft lithography fabrication which has allowed researchers from different disciplines, with incomplete technical knowledge, to develop and use new devices for their own research problems. In this chapter, we describe a simple fabrication process that will allow investigators to make microfluidic devices for in vivo imaging studies using genetic model organisms such as C. elegans, Drosophila larvae, and zebrafish larvae. This microfluidic technology enables detailed studies on multiple cellular and subcellular phenomena including intracellular vesicle trafficking in living organisms over different developmental stages in an anesthetic free environment.

Challenges in neuroprotective nanomedicine development: progress towards noninvasive gene therapy of glaucoma

Over the past decade the application of gene therapy of retinal diseases such as glaucoma has produced promising results. However, optic nerve regeneration and restoration of vision in patients with glaucoma is still far from reality. Neuroprotective approaches in the form of gene therapy may provide significant advantages, but are still limited by many factors both at the organ and cellular levels. In general, gene delivery systems for eye diseases range from simple eye drops and ointments to more advanced bio- and nanotechnology-based systems such as muco-adhesive systems, polymers, liposomes and ocular inserts. Most of these technologies were developed for front-of-the-eye ophthalmic therapies and are not applicable as back-of-the-eye delivery systems. Currently, only the invasive intravitreal injections are capable of successfully delivering genes to the retina. Here we review the challenges and possible strategies for the noninvasive gene therapy of glaucoma including the barriers in the eye and in neural cells, and present a cross-sectional view of gene delivery as it pertains to the prevention and treatment of glaucoma.

Immunofluorescence microscopy

Immunofluorescence microscopy is a powerful technique that is widely used by researchers to assess both the localization and endogenous expression levels of their favorite proteins. The application of this approach to C. elegans, however, requires special methods to overcome the diffusion barrier of a dense, collagen-based outer cuticle. This chapter outlines several alternative fixation and permeabilization strategies for overcoming this problem and for producing robust immunohistochemical staining of both whole animals and freeze-fractured samples. In addition, we provide an accounting of widely used antibody reagents available to the research community. We also describe several approaches aimed at reducing non-specific background often associated with immunohistochemical studies. Finally, we discuss a variety of approaches to raise antisera directed against C. elegans antigens.

Axon regeneration mechanisms: insights from C. elegans

Understanding the mechanisms of axon regeneration is of great importance to the development of therapeutic treatments for spinal cord injury or stroke. Axon regeneration has long been studied in diverse vertebrate and invertebrate models, but until recently had not been analyzed in the genetically tractable model organism Caenorhabditis elegans. The small size, simple neuroanatomy, and transparency of C. elegans allows single fluorescently labeled axons to be severed in live animals using laser microsurgery. Many neurons in C. elegans are capable of regenerative regrowth, and can in some cases re-establish functional connections. Large-scale genetic screens have begun to elucidate the genetic basis of axon regrowth.