DRG न्यूरॉन्स की DiI लेबल axonal अध्ययन माउस भ्रूणीय स्पाइनल कॉर्ड के एक साबुत माउंट तैयारी में शाखाओं में बंटी
Summary
कृंतक रीढ़ की हड्डी में संवेदी afferents के स्टिरियोटाइप अनुमानों एक आसानी से सुलभ प्रयोगात्मक प्रणाली एकल axons की अनुरेखण के माध्यम से axonal शाखाओं में अध्ययन की पेशकश करते हैं.
Abstract
Here we present a technique to label the trajectories of small groups of DRG neurons into the embryonic spinal cord by diffusive staining using the lipophilic tracer 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate (DiI)1. The comparison of axonal pathways of wild-type with those of mouse lines in which genes are mutated allows testing for a functional role of candidate proteins in the control of axonal branching which is an essential mechanism in the wiring of the nervous system. Axonal branching enables an individual neuron to connect with multiple targets, thereby providing the physical basis for the parallel processing of information. Ramifications at intermediate target regions of axonal growth may be distinguished from terminal arborization. Furthermore, different modes of axonal branch formation may be classified depending on whether branching results from the activities of the growth cone (splitting or delayed branching) or from the budding of collaterals from the axon shaft in a process called interstitial branching2 (Fig. 1).
The central projections of neurons from the DRG offer a useful experimental system to study both types of axonal branching: when their afferent axons reach the dorsal root entry zone (DREZ) of the spinal cord between embryonic days 10 to 13 (E10 – E13) they display a stereotyped pattern of T- or Y-shaped bifurcation. The two resulting daughter axons then proceed in rostral or caudal directions, respectively, at the dorsolateral margin of the cord and only after a waiting period collaterals sprout from these stem axons to penetrate the gray matter (interstitial branching) and project to relay neurons in specific laminae of the spinal cord where they further arborize (terminal branching)3. DiI tracings have revealed growth cones at the dorsal root entry zone of the spinal cord that appeared to be in the process of splitting suggesting that bifurcation is caused by splitting of the growth cone itself4 (Fig. 2), however, other options have been discussed as well5.
This video demonstrates first how to dissect the spinal cord of E12.5 mice leaving the DRG attached. Following fixation of the specimen tiny amounts of DiI are applied to DRG using glass needles pulled from capillary tubes. After an incubation step, the labeled spinal cord is mounted as an inverted open-book preparation to analyze individual axons using fluorescence microscopy.
Protocol
Discussion
टकसाली प्रक्षेपण axonal शाखा गठन के दोनों प्रकार की तैयारी के DiI लेबलिंग के लिए तय ऊतक के उपयोग के साथ संयोजन में आसानी से एक साथ शामिल पैटर्न संलग्न DRG शाखाओं में बंटी axonal अध्ययन के लिए एक अनुकूल मॉडल के साथ भ?…
Disclosures
The authors have nothing to disclose.
Acknowledgements
लेखकों के लिए उपयोगी टिप्पणी के लिए डॉ. एलिस्टेयर Garratt (अधिकतम Delbrück केंद्र, बर्लिन) धन्यवाद करना चाहते हैं. यह काम जर्मन अनुसंधान परिषद (DFG) के सहयोगात्मक अनुसंधान केंद्र (SFB665) द्वारा समर्थित किया गया.
Materials
| Name of the reagent | Company | Catalogue number | Comments (optional) |
| Stereomicroscope Stemi DRC | Zeiss | ||
| Phosphate-buffered solution (PBS) | Biochrom AG | L182-50 | |
| Paraformaldehyde | Merck | 8.18715.1000 | |
| Standard surgical scissors | Fine Science Tools | 14001-13 | |
| Toothed standard forceps | Fine Science Tools | 11021-14 | |
| Extra fine iris scissors | Fine Science Tools | 14088-10 | |
| Curved forceps | Fine Science Tools | 11003-13 | |
| Dumont No.5 fine tips forceps | Fine Science Tools | 11254-20 | |
| Dumont No.5 mirror finish forceps | Fine Science Tools | 11252-23 | |
| Vannas-Tübingen spring scissors | Fine Science Tools | 15008-08 | |
| Filter paper | Fisher Scientific | FB59041 | |
| Sylgard 184 | World Precission Instruments | SYLG184 | |
| 100-mm Petri dishes | Greiner | 663102 | |
| 12-ml polypropylene tube | Carl Roth GmbH | ECO3.1 | |
| 12-well culture plate | Becton Dickinson | 35-3043 | |
| Ethanol | Merck | 1.00983.2500 | |
| Flaming/Brown micropipette puller P-97 | Sutter Instrument Co. | ||
| Borosilicate glass capillaries | Harvard Apparatus | 30-0066 | |
| DiI (1,1′-Dioctadecyl-3,3,3′,3′-tetramethyl–indocarbocyanine perchlorate) | Sigma-Aldrich | 468495 | |
| Microscope slides SuperFrost Plus | Carl Roth GmbH | H867.1 | |
| Glass cover slips | Carl Roth GmbH | 1870.2 |
References
- Honig, M. G., Hume, R. I. Dil and diO: versatile fluorescent dyes for neuronal labelling and pathway tracing. Trends. Neurosci. 12 (9), 333-333 (1989).
- Acebes, A., Ferrus, A. Cellular and molecular features of axon collaterals and dendrites. Trends. Neurosci. 23 (11), 557-557 (2000).
- Ozaki, S., Snider, W. D. Initial trajectories of sensory axons toward laminar targets in the developing mouse spinal cord. J. Comp. Neurol. 380 (2), 215-215 (1997).
- Schmidt, H. The receptor guanylyl cyclase Npr2 is essential for sensory axon bifurcation within the spinal cord. J. Cell Biol. 179 (2), 331-331 (2007).
- Gibson, D. A., Ma, L. Developmental regulation of axon branching in the vertebrate nervous system. Development. 138 (2), 183-183 (2011).
- O’Leary, D. D., Terashima, T. Cortical axons branch to multiple subcortical targets by interstitial axon budding: implications for target recognition and "waiting periods". Neuron. 1 (10), 901-901 (1988).
- Portera-Cailliau, C. Diverse modes of axon elaboration in the developing neocortex. PLoS. Biol. 3 (8), e272-e272 (2005).
- Gan, W. B. Vital imaging and ultrastructural analysis of individual axon terminals labeled by iontophoretic application of lipophilic dye. J. Neurosci. Methods. 93 (1), 13-13 (1999).
- Schmidt, H. C-type natriuretic peptide (CNP) is a bifurcation factor for sensory neurons. Proc. Natl. Acad. Sci. U. S. A. 106 (39), 16847-16847 (2009).
- Zhao, Z. Regulate axon branching by the cyclic GMP pathway via inhibition of glycogen synthase kinase 3 in dorsal root ganglion sensory neurons. Journal of Neuroscience. 29 (5), 1350-1350 (2009).
- Zhao, Z., Ma, L. Regulation of axonal development by natriuretic peptide hormones. Proc. Natl. Acad. Sci. U. S. A. 106 (42), 18016-18016 (2009).
- Schmidt, H., Rathjen, F. G. Signalling mechanisms regulating axonal branching in vivo. Bioessays. , (2010).
- Feng, G. Imaging neuronal subsets in transgenic mice expressing multiple spectral variants of GFP. Neuron. 28 (1), 41-41 (2000).
- Livet, J. Transgenic strategies for combinatorial expression of fluorescent proteins in the nervous system. Nature. 450 (7166), 56-56 (2007).
