Fluoro-Gold and Fluoro-Ruby Neuronal Tracers
The formation of highly ordered neural networks is essential for the assembly of functional nervous systems. Correlating functional information with the intricate anatomy of specific neural circuitry provides a better understanding of these higher brain structures and helps to evaluate changes in neural networks in conditions of disease and injury. Neuronal tracers allow visualization of the anatomical connections of neurons. The tracers can be classified according to their direction of axonal transport. Anterograde tracers are taken up by cell body or dendrites and transported down axons to nerve terminals. Retrograde tracers are taken up at the nerve terminals and transported to the cell body. In addition, trans-synaptic tracers can be transferred from original neurons to synaptically connected neurons. Neuroanatomical studies based on the use of tracers can provide detailed information on cellular projections and consequently morphology and also can reveal information on the organization and potential regulation of neural networks.
Fluorescent tracers can be used to study capillary flow, define neuronal cell connectivity, study dye translocation through gap junctions, and track cell division, cell lysis, and cell movement. Fluorescent retrograde and anterograde tracers offer some distinct advantages in neuroanatomical studies. First, the labels are directly visible under a fluorescence microscope without any histochemical or immunohistochemical treatment. Second, many of these tracers can be used to trace extremely long fiber tracts, such as corticospinal and bulbospinal projections. Finally, because of their spectral properties, fluorescent retrograde tracers are ideal for the study of axon collateralization in dual-labeling experiments and for the study of the neurochemical identity of traced fiber projections in a multi-dimensional setting in combination with immunofluorescence.
Fast Blue, Fluoro-Ruby, Fluoro-Emerald, Fluoro-Gold and DiI are fluorescent tracers that have been used successfully in many animal models for neuroanatomical studies. Fast Blue is a tracer related to true blue but can be transported more rapidly and efficiently over long distances. It is transported by axons in living neurons and has good tissue penetration. Its bright blue fluorescence is produced by broadband UV excitation. DiI is a lipophilic carbocyanine dye that labels living cells by axonal transport and labels fixed cells by lateral diffusion through phospholipid membranes. DiI is a non-toxic tracer that can be used for anterograde and retrograde labeling.
Fluoro-Ruby and Fluoro-Emerald are dextran conjugates and are non-toxic and relatively inert. They can bind covalently to lysine residues, allowing binding to surrounding tissue molecules after paraformaldehyde fixation. Fluoro-Ruby and Fluoro-Emerald can be transported in living axons by anterograde and retrograde transport. Fluoro-Ruby can produce deep red fluorescence, and Fluoro-Emerald can produce bright green fluorescence.
Fluoro-Gold is a water-soluble crystal tracer that produces a golden yellow fluorescence under broad band UV excitation. Fluoro-Gold is fluorescent stilbene derivative. It can be used as a retrograde tracer for neurons and a histochemical stain. This dye can be injected by either pressure, iontophoretic and other methods into the region of interest, where it is taken up by damaged neurons and at nerve terminals by fluid-phase endocytosis. Fluoro-Gold is one of the most commonly used retrograde fluorescent tracers, especially suitable for targeted deep imaging of the nervous system.
| Product |
Type |
Size |
| Fluoro-Gold |
Retrograde Axonal Tracer |
20 mg; 50 mg |
| Fluoro-Ruby |
Anterograde and Retrograde Axonal Tracer |
30 mg |
Antibody to Fluoro-Gold
The advantage of Fluoro-Gold is the availability of specific antibodies against this tracer. Immunostaining can then be converted to a permanent electron-dense precipitate by the use of a biotinylated secondary antibody followed by treatment with an avidin-HRP conjugate and then reaction with DAB.
Labeled Neurons with Fluoro-Gold
Photomicrograph of a DAPI- stained longitudinal section through a mouse right cervical cord illustrating a typical column of Fluoro-Gold labeled motor neurons. (Tosolini AP, Mohan R, Morris R (2013). Targeting the full length of the motor end plates regions in the mouse forelimb increases the uptake of Fluoro-Gold into corresponding spinal cord motor neurons. Front. Neurol. 4:58,1-10,4)
Intense positive Fluoro-Gold labeled motor neurons in rat forelimb. (Tosolini AP. Mohan R (2012). Spatial characterization of the motor neuron columns supplying the rat forelimb. Neuroscience 200:19-30,22)
Labeled Neurons with Fluoro-Ruby
Fluoro-Ruby labeled axons and terminals
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