Name: whole-mount imaging of mouse embryo sensory axon projections
Uploaded: 2014-12-09T14:00:00.000+00:00
Duration: 8 min 37 s
Description: Watch this Scientific Journal Video about Whole-mount Imaging of Mouse Embryo Sensory Axon Projections at JoVE.com

Die Autoren danken Dr. Louis Reichardt für die TrkA taulacZ Mäusen und Dr. Annette Markus für aufschlussreiche Diskussionen und Anregungen. Diese Arbeit wurde durch Mittel aus dem Startup-Burke-Stiftung sowie Whitehall-Stiftung Forschungsstipendium 2010-08-61, ein Forschungsstipendium von Wings for Life Foundation (WFL-US-028/14) unterstützt wird, gewähren ZB1-1102-1 von der Christopher &amp; Dana Reeve Foundation, und Zuschüsse 1R01EY022409 und 3R01EY022409-01S1 vom National Eye Institute, zu JZ. KJO ist ein Goldsmith Kerl.

Hinweis: Alle Verfahren mit dem NIH Leitfaden für die Benutzung und Pflege von Labortieren entsprechen. Das Tier Protokoll wurde von der IACUC am Weill Cornell Medical College zugelassen. 1. Gewebepräparation <ol><li> Euthanize timed-Schwangerschaft Frauen durch Genickbruch 15. Präparieren embryonalen E16 - E18 Embryonen aus timed-Schwangerschaft Weibchen und Ort Embryonen einzeln in die Wells einer 6-Well-Platte, mit kalter phosphatgepufferter Salzlösung (PBS) gefüllt. </li><li> Spülen Embryonen in kaltem PBS. </li><li> Entfernen eines kleinen Teils der Amnionmembran des Embryos und in eine vorbereitete Proteinase K-Lösung für die nachfolgende Genotypisierung. Alternativ, wenn die Amnionmembran verloren geht, nehmen Sie einen kleinen Teil der Spitze des Embryos Schwanz und ihn in Proteinase K-Lösung </li><li> Poke Löcher in die Haut rund um den Embryo mit Insektenstifte (mindestens 100 pro Seite). </li><li> Entfernen PBS und langsam frisch 2% Paraformaldehyd (PFA),pH 7,4, zum Brunnen. </li><li> Schütteln für 2 h bei 4 ° C. </li><li> Embryonen zweimal Spülen in PBS und lagern in PBS bei 4 ° C bis zur Färbung. </li></ol> 2. Genotypisierung <ol><li> Tauchen Amnionmembranen oder Embryo Schwänze in Proteinase K Mischung gemäß den Anweisungen des Herstellers. </li><li> Inkubiere bei 56 ° C für 10 min. </li><li> Extrahieren DNA unter Verwendung eines kommerziell erhältlichen DNA-Reinigungskits. </li><li> Nehmen 0,5 ul der gesamten 200 ul gereinigte genomische DNA-Lösung, kombiniert mit 0,5 &amp; mgr; l von jeder der genspezifischen Sense- und Antisense-Primer (10 &amp; mgr; M), 2 &amp; mgr; l dNTP-Mix (2,5 mM dATP, dCTP, dGTP und dTTP) , 0,2 ul Taq-Polymerase (5 U / ul) und 2 ul PCR-Puffer (10x), fügen H 2 O auf ein Gesamtvolumen von 20 ul. HINWEIS: Die Primersequenzen sind wie folgt (Tabelle 1): TrkA: TrkA_F: GCG GGC GCC GCC GCG ATG, TrkA_R: GAA GCC GCC TGC GCG GCT CTG CCA GGG TG; PCR fragment Länge: 400 Basenpaare (bp). Bax: In5R: GTT GAC CAG AGT GGC GTA GG, Ex5F: TGA TCA GAA CCA TCA TG, NeoR: CCG CTT CCA TTG CTC AGC GG; PCR-Fragment Längen: Wildtyp, 304 bp; Bax null, 507 bp. TauLacZ: lacZup: ACA ACG TCG TGA GTG GGA AAA, lacZdown: ATC AAC ATT AAA TGT GAG CGA G; PCR-Fragment-Längen: 360 bp. </li><li> Führen einer PCR mit dem folgenden Programm für TrkA: Schritt 1: 1 min bei 95 ° C, Stufe 2: 10 sec bei 95 ° C, Stufe 3: 20 sec bei 68 ° C, Stufe 4: 30 sec bei 72 ° C. Wiederholen Sie die Schritte 2-4 für 40 Zyklen. <ol><li> Für LacZ und Bax, führen eine PCR nach folgendem Programm: Schritt 1: 1 min bei 95 ° C, Stufe 2: 10 sec bei 95 ° C, Stufe 3: 1 min bei 54 ° C, Schritt 4: 1 min bei 72 ° C, wiederholen Sie die Schritte 2-4 für 35 Zyklen. </li></ol></li><li> Run PCR-Proben auf einem 2% Agarosegel bei 100 V in 1x Tris-Acetat-EDTA-Puffer für 20 min mit einer Spur-DNA-Leiter, um Fragmentlängen abzuschätzen. </li><li> Analysieren Embryonen für die Anwesenheit von Wildtyp-TrkA, TRKA-tauLacZ und Bax Nullallele. Die Genotypen der experimentellen Embryonen TrkA taulacZ / WT: Bax - / - und TrkA taulacZ / taulacZ: Bax - / - in Abhängigkeit von den experimentellen Fragen. Embryonen ohne die tauLacZ Reporter negativ für axonalen Färbung sein und kann daher dazu dienen als Negativkontrollen, um den Färbeprozess zu kalibrieren. </li></ol> 3. Embryo Färbung <ol><li> Verwenden eines kommerziellen Kits zur LacZ-Färbung mit einigen Änderungen, wie unten in den Abschnitten 3.2 - 3.8. Hier verwenden Sie die Millipore-Kit. </li><li> Tauchen Embryonen in Puffer A für mindestens 1 h bei Raumtemperatur vorsichtig schütteln. </li><li> Direkt tauchen Embryonen in Puffer B für mindestens 15 min bei Raumtemperatur vorsichtig schütteln. </li><li> Während Embryonen werden in Puffer A / B, vorwärmen Tissue Basislösung bei 37 ° C. Verwenden Sie 5 ml Gewebebasislösung pro Embryo. </li><li> Während Embryonen in Puffer A / B, bereiten Sie frisches 5-bromo- 4- Chlor- 3- indolyl α-D-galactopyranosid (X-gal) bei einer Konzentration von 40 mg / ml in 100% Dimethylsulfoxid (DMSO). </li><li> Verdünne X-gal in die vorgewärmte Tissue Basenlösung mit einer Konzentration von 1 mg / ml und 5 ml X-gal / Tissue Basismischung auf eine Glasszintillationsröhrchen. </li><li> Übertragen Embryonen auf ein Glasszintillationsröhrchen enthaltende X-gal / Tissue Basismischung. Seal Deckel mit Parafilm und bei 37 ° C über Nacht, Prüfen auf Vorhandensein von Bläue. </li><li> Postfix Embryonen mit frischen 4% PFA, pH-Wert 7,4. Schütteln 4 Stunden bei 4 ° C. </li><li> Embryonen zweimal Spülen in kaltem PBS. </li></ol> 4. Tissue Dehydration und Clearing <ol><li> Ort Embryonen in 50% Methanol / 50% PBS Gemisch 30 min bei Raumtemperatur in den Glasphiolen Schütteln. </li><li> Weiterhin in 75% Methanol / 25% PBS für 30 Minuten bei Raumtemperatur dehydriert, in Glasfläschchen schüttelnd. </li><li> Weiterhin in 90% entwässern Methanol / 10% PBS 30 Minuten lang bei Raumtemperatur in Glasfläschchen schüttelnd. </li><li> Weiter in 100% Methanol für 30 min (2x) bei Raumtemperatur zu entwässern, in Glasfläschchen schüttelnd. </li><li> Während Embryonen Dehydratisierung, bereiten ein 1: 1 (v: v) Mischung aus Benzoylperoxid Alkohol und Benzoylbenzoat. HINWEIS: Benzoyl Alkohol und Benzoylbenzoat ist giftig. </li><li> Tauchen Embryonen in 1: 1 (v: v) Mischung aus 100% Methanol: 100% BABB für 15 min. Benutzen Glas nur, weil die BABB wird Kunststoff auflösen. </li><li> Tauchen Embryonen in 100% BABB völlig klar, dass die Gewebe und X-Gal-Färbung in der gelöscht Embryo sichtbar zu machen. HINWEIS: Bild so schnell wie möglich, weil die X-gal-Färbung mit der Zeit verblassen. </li></ol> 5. Ganze Berge Imaging <ol><li> Stabilisierung des Embryos, in 100% BABB getaucht, an den entsprechenden Winkel für die Fotografie mit Metallzangen. Beleuchten Sie mit einer Kombination aus bis-Licht und unter Lichtlichtquellen. </li><li> Erwerben Sie Bilder mit einem Binokularmit einer Digitalkamera ausgestattet. Nehmen Sie mehrere Hellfeldaufnahmen an fünf aufeinander folgenden Brennebenen 0,5 mm, die entlang der Z-Achse. Belichtungszeiten und Blendenstufen können nach Beleuchtung und Kameradaten variieren und müssen für jedes Setup optimiert werden. </li><li> Verwenden Sie Standard-Bildverarbeitungs-Software, um Overlay-Bilder verarbeiten und Fotomontagen. </li></ol>

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The authors declare that there are no competing interests.

Die oben beschriebene X-gal Färbeverfahren embryonaler TrkA taulacZ Mäusen erlaubt die schnelle und präzise Visualisierung Fern Axon in der intakten Fest Embryo. Aufgrund der Bax null Hintergrund diese Mäuse ermöglichen die Untersuchung von Signalmechanismen, die sowohl Axon Wachstum und Überleben von Neuronen beitragen können. Paarung mit transgenen oder Knockout-Mäuse von Interesse ermöglicht die umfassende Beurteilung der axonalen Phänotypen und kann als nützlicher Leitfaden f?...

Gründung der genauen neuronalen Netzen ist eine komplexe Entwicklungsprozess wesentlich für die Funktion des Nervensystems. Störung in diesem Verfahren führt zu neuronalen Funktionsstörungen, die in menschlichen neurologischen Erkrankungen 1-3 gebracht wurde. Um die zugrunde liegenden molekularen Mechanismen der Axon Wachstum und Ziel Innervation bei Säugetieren zu untersuchen, haben wir ein Protokoll, um die axonalen Bahnen der TrkA-exprimierenden sensorischen Neuronen mit einer Kombination von zwei genetisch veränderten Mauslinien zu visualisieren entwickelt. TrkA ist ein Rezeptor für den Nervenwachstumsfaktor NGF und ein Funktionsmarker nozizeptiven sensorischen Neuronen 4. TrkA ist stark in nozizeptiven Neuronen während der frühen Entwicklung ausgedrückt und vermittelt NGF-abhängige Überleben von Neuronen, das Wachstum von Axonen, Verzweigung und Ziel Innervation 5-9. In TrkA taulacZ Mäusen wird die Wildtyp-TrkA-Gen von einem taulacZ Ausdruck c ersetztassette 10, derart, dass die axonale Morphologie putative TrkA-positive Neurone kann durch β-Gal (X-gal) Anfärben 11 visualisiert werden. Mit einem heterozygot TrkA taulacZ / WZ-Linie, können wir Faktoren, die zu regulieren oder zu stören die Entwicklung der sensorischen afferenten Projektionen in vivo kann zu untersuchen. Außerdem ist TrkA Expression in homozygoten TrkA taulacZ / taulacZ Mäusen, die daher verwendet werden können, um das Wachstum der Axone zu fördern Mechanismen in Abwesenheit von NGF / TrkA Signalisierungs beurteilen abwesend. Seit nozizeptiven Neuronen hängt von NGF / TrkA Signalisierung nicht nur für das Wachstum von Axonen, sondern auch für das Überleben, setzen wir einen weiteren Mauslinie, ohne die pro-apoptotische Bax-Gens, die Apoptose in embryonalen DRG-Neuronen hemmen, retten sie vor Zelltod, die sonst ist in Abwesenheit von TrkA Signalisierungs beobachtet. Das Bax - / - Hintergrund 12 ermöglicht somit die Molekular Dissektion von Signalwegen, die speziell beeinflussen Axonwachstum 7-9,13-15. In TrkA - / -: Bax - / - Mäuse, DRG-Neuronen überleben, aber sensorischen afferenten Innervation der Haut vollständig abgeschafft 14,15. Wir können selektiv aktiviert Signalwege auf ihre jeweiligen Beiträge zur Entwicklung von Axon Projektionen zu bestimmen. Der Nutzen dieser Methode ist, dass sie die Beurteilung der Änderungen im Wachstum der Nervenfasern Phänotypen, wenn verschiedene genetische Veränderungen werden auf die TrkA taulacZ / taulacZ gezüchtet: Bax - / - oder TrkA taulacZ / WT: Bax - / - Hintergründe.

<table><tbody><tr><td>PFA</td><td>Sigma-Aldrich</td><td>P6418</td><td></td></tr><tr><td>PBS</td><td>Life Tech</td><td>10010-023</td><td></td></tr><tr><td>Tissue Rinse Solution A</td><td>Millipore</td><td>BG-6-B</td><td></td></tr><tr><td>Tissue Rinse Solution B</td><td>Millipore</td><td>BG-7-B</td><td></td></tr><tr><td>Tissue Stain Base Solution</td><td>Millipore</td><td>BG-8-C</td><td></td></tr><tr><td>X-gal</td><td>Sigma-Aldrich</td><td>B4252</td><td></td></tr><tr><td>Glass scintiallation vial</td><td>Kimble Chase</td><td>74500-20</td><td></td></tr><tr><td>Incubator</td><td>Labline</td><td>Model 120</td><td></td></tr><tr><td>Insect pins</td><td>FST</td><td>26000-30</td><td></td></tr><tr><td>DMSO</td><td>Sigma-Aldrich</td><td>D8418</td><td></td></tr><tr><td>6-well dish</td><td>USA Scientific</td><td>CC7672-7506</td><td></td></tr><tr><td>Primers</td><td>IDT</td><td>custom DNA primers</td><td></td></tr><tr><td>Takara dNTP mixture</td><td>Takara</td><td>4030</td><td></td></tr><tr><td>Takara LA buffer</td><td>Takara</td><td>RR002A</td><td></td></tr><tr><td>Takara LA Taq</td><td>Takara</td><td>RR002A</td><td></td></tr><tr><td>PCR machine</td><td>Bio-Rad</td><td>DNA Engine Dyad</td><td></td></tr><tr><td>Benzyl alcohol</td><td>Sigma-Aldrich</td><td>B-1042</td><td></td></tr><tr><td>Benzyl benzoate</td><td>Sigma-Aldrich</td><td>B-6630</td><td></td></tr><tr><td>Dissecting microscope</td><td>Leica</td><td>M205A</td><td></td></tr><tr><td>Camera</td><td>Leica</td><td>DFC310FX</td><td></td></tr><tr><td>Ring light</td><td>Leica&amp;nbsp;</td><td>MEB110</td><td></td></tr><tr><td>Photoshop</td><td>Adobe</td><td>Photoshop 4.0</td><td></td></tr></tbody></table>

whole-mount imaging of mouse embryo sensory axon projections

Die Visualisierung der in voller Länge neuronalen Projektionen in Embryonen ist wesentlich für ein Verständnis, wie Säugetier neuronale Netze entwickeln zu gewinnen. Hier beschreiben wir eine Methode, um in situ zu markieren eine Teilmenge der Hinterwurzelganglien (DRG) Axon ihrer phänotypischen Eigenschaften beurteilen mit mehreren genetisch manipulierte Mauslinien. Die TrkA-positive Neurone nociceptor Neuronen, für die Übertragung von Schmerzsignalen gewidmet. Wir nutzen eine TrkA taulacZ Mauslinie, die Flugbahnen aller TrkA-positiven peripheren Axonen im intakten Mausembryo zu kennzeichnen. Wir züchten ferner den TrkA taulacZ Schnur auf eine Bax null Hintergrund, die im Wesentlichen aufhebt neuronale Apoptose, um wachstumsbedingte stellen unabhängig von möglichen Wirkungen von genetischen Manipulationen auf das neuronale Überleben zu beurteilen. Anschließend werden gentechnisch veränderte Mäuse von Interesse mit der TrkA Taul gezüchtetlacZ / Bax Nulllinie und sind dann bereit für die Studie unter Verwendung der hierin beschriebenen Techniken. Diese Präsentation enthält detaillierte Informationen über Maus Zuchtpläne, Genotypisierung bei der Dissektion, Gewebevorbereitung, Färbung und Clearing zur Visualisierung von voller Länge axonalen Bahnen ganz-mount Vorbereitung zu ermöglichen.

Die Genotypen von TrkA WT / taulacZ: Bax - / - und TrkA taulacZ / taulacZ: Bax - / - Embryonen können eindeutig durch Standard-PCR Genotypisierung bestimmt werden (Abbildung 1). X-Gal-Färbung zeigt detaillierte periphere axonale Verzweigungen subkutan in konventionell gefärbten Embryonen (Figuren 2, 3a), und während der Embryo nach Gewebe Clearing (3b, 4). / - - Linie mit Mäusen, di...

Watch this Scientific Journal Video about Whole-mount Imaging of Mouse Embryo Sensory Axon Projections at JoVE.com

Whole-mount Imaging of Mouse Embryo Sensory Axon Projections

We present here an optimized protocol to genotype, stain and prepare fetal mice for the imaging of peripheral nociceptor axon projections in the whole animal, as an effective method to assess sensory axon growth phenotypes in developing genetically engineered mice.

Whole-Mount-Imaging von Mouse Embryo Sinnes Axon Projektionen

The visualization of full-length neuronal projections in embryos is essential to gain an understanding of how mammalian neuronal networks develop. Here we ...

whole-mount-imaging-of-mouse-embryo-sensory-axon-projections

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Neuroscience

10.0K Aufrufe.  Weill Medical College of Cornell University. We present here an optimized protocol to genotype, stain and prepare fetal mice for the imaging of peripheral nociceptor axon projections in the whole animal, as an effective method to assess sensory axon growth phenotypes in developing genetically engineered mice.

Serie: Whole-mount Imaging of Mouse Embryo Sensory Axon Projections

Organotypic Slice Culture of GFP-expressing Mouse Embryos for Real-time Imaging of Peripheral Nerve Outgrowth

For many purposes, the cultivation of mouse embryos ex vivo as organotypic slices is desirable. For example, we employ a transgenic mouse line (tauGFP) in which the enhanced version of the green fluorescent protein (EGFP) is exclusively expressed in all neurons of the developing central and peripheral nervous system1, allowing the possibility to both film the innervation of the forelimb and to manipulate this process with pharmacological and genetic techniques2. The most critical parameter in the successful cultivation of such slice cultures is the method by which the slices are prepared. After extensive testing of a variety of methods, we have found that a vibratome is the best possible device to slice the embryos such that they routinely result in a culture that demonstrates viability over a period of several days, and most importantly, develops in an age-specific manner. For mid-gestation embryos, this includes the normal outgrowth of spinal nerves from the spinal cord and the dorsal root ganglia to their targets in the periphery and the proper determination of skeletal and muscle tissue. 
In this work, we present a method for processing whole embryos of embryonic day (E) E10 to E12 into 300 - 400 micrometer slices for cultivation in a standard tissue culture incubator, which can be studied for up to two days after slice preparation. Critical for the success of this approach is the use of a vibratome to slice each agarose-embedded embryo. This is followed by the cultivation of the slices upon Millicell culture membrane inserts placed upon a small volume of medium, resulting in an interface culture technique. One litter with an average of 7 embryos routinely produces at least 14 slices (2-3 slices of the forelimb region per embryo), which varies slightly due to the age of the embryos as well as to the thickness of the slices. About 80% of the cultured slices show nerve outgrowth, which can be measured througout the culturing period2. Representative results using the tauGFP mouse line are demonstrated.

We present a method to prepare organotypic slices of mid-gestation mouse embryos for the cultivation and time-lapse imaging of peripheral nerve outgrowth.

Organotypischen Kultur der GFP-exprimierenden Maus Embryonen für Real-time Imaging der peripheren Nerven Outgrowth

For many purposes, the cultivation of mouse embryos ex vivo as organotypic slices is desirable. For example, we employ a transgenic mouse line (tauGFP) in ...

Forschung

Neurowissenschaften

Micron-scale Resolution Optical Tomography of Entire Mouse Brains with Confocal Light Sheet Microscopy

Understanding the architecture of mammalian brain at single-cell resolution is one of the key issues of neuroscience. However, mapping neuronal soma and projections throughout the whole brain is still challenging for imaging and data management technologies. Indeed, macroscopic volumes need to be reconstructed with high resolution and contrast in a reasonable time, producing datasets in the TeraByte range. We recently demonstrated an optical method (confocal light sheet microscopy, CLSM) capable of obtaining micron-scale reconstruction of entire mouse brains labeled with enhanced green fluorescent protein (EGFP). Combining light sheet illumination and confocal detection, CLSM allows deep imaging inside macroscopic cleared specimens with high contrast and speed. Here we describe the complete experimental pipeline to obtain comprehensive and human-readable images of entire mouse brains labeled with fluorescent proteins. The clearing and the mounting procedures are described, together with the steps to perform an optical tomography on its whole volume by acquiring many parallel adjacent stacks. We showed the usage of open-source custom-made software tools enabling stitching of the multiple stacks and multi-resolution data navigation. Finally, we illustrated some example of brain maps: the cerebellum from an L7-GFP transgenic mouse, in which all Purkinje cells are selectively labeled, and the whole brain from a thy1-GFP-M mouse, characterized by a random sparse neuronal labeling.

In this article we describe the full experimental procedure to reconstruct, with high resolution, the fine brain anatomy of fluorescently labeled mouse brains. The described protocol includes sample preparation and clearing, specimen mounting for imaging, data post-processing and multi-scale visualization.

Micron-Skala Resolution Optical Tomography von Entire Gehirn der Maus mit der konfokalen Mikroskopie Licht Blatt

Understanding the architecture of mammalian  brain at single-cell resolution is one of the key issues of neuroscience.  However, mapping neuronal soma and ...

Live Imaging of Mitosis in the Developing Mouse Embryonic Cortex

Although of short duration, mitosis is a complex and dynamic multi-step process fundamental for development of organs including the brain. In the developing cerebral cortex, abnormal mitosis of neural progenitors can cause defects in brain size and function. Hence, there is a critical need for tools to understand the mechanisms of neural progenitor mitosis. Cortical development in rodents is an outstanding model for studying this process. Neural progenitor mitosis is commonly examined in fixed brain sections. This protocol will describe in detail an approach for live imaging of mitosis in ex vivo embryonic brain slices. We will describe the critical steps for this procedure, which include: brain extraction, brain embedding, vibratome sectioning of brain slices, staining and culturing of slices, and time-lapse imaging. We will then demonstrate and describe in detail how to perform post-acquisition analysis of mitosis. We include representative results from this assay using the vital dye Syto11, transgenic mice (histone H2B-EGFP and centrin-EGFP), and in utero electroporation (mCherry-&#945;-tubulin). We will discuss how this procedure can be best optimized and how it can be modified for study of genetic regulation of mitosis. Live imaging of mitosis in brain slices is a flexible approach to assess the impact of age, anatomy, and genetic perturbation in a controlled environment, and to generate a large amount of data with high temporal and spatial resolution. Hence this protocol will complement existing tools for analysis of neural progenitor mitosis.

Neural progenitor mitosis is a critical parameter of neurogenesis. Much of our understanding of neural progenitor mitosis is based on analysis of fixed tissue. Live imaging in embryonic brain slices is a versatile technique to assess mitosis with high temporal and spatial resolution in a controlled environment.

Live-Imaging der Mitose in der Entwicklung von embryonalen Maus-Cortex

Although of short duration, mitosis is a complex and dynamic multi-step process fundamental for development of organs including the brain. In the ...

Microinjection of DNA into Eyebuds in Xenopus laevis Embryos and Imaging of GFP Expressing Optic Axonal Arbors in Intact, Living Xenopus Tadpoles

The primary visual projection of tadpoles of the aquatic frog Xenopus laevis serves as an excellent model system for studying mechanisms that regulate the development of neuronal connectivity. During establishment of the retino-tectal projection, optic axons extend from the eye and navigate through distinct regions of the brain to reach their target tissue, the optic tectum. Once optic axons enter the tectum, they elaborate terminal arbors that function to increase the number of synaptic connections they can make with target interneurons in the tectum. Here, we describe a method to express DNA encoding green fluorescent protein (GFP), and gain- and loss-of-function gene constructs, in optic neurons (retinal ganglion cells) in Xenopus embryos. We explain how to microinject a combined DNA/lipofection reagent into eyebuds of one day old embryos such that exogenous genes are expressed in single or small numbers of optic neurons. By tagging genes with GFP or co-injecting with a GFP plasmid, terminal axonal arbors of individual optic neurons with altered molecular signaling can be imaged directly in brains of intact, living Xenopus tadpoles several days later, and their morphology can be quantified. This protocol allows for determination of cell-autonomous molecular mechanisms that underlie the development of optic axon arborization in vivo.

Microinjection of DNA into Eyebuds in Xenopus laevis Embryos and Imaging of GFP Expressing Optic Axonal Arbors in Intact, Living Xenopus Tadpoles

This protocol aims to demonstrate how to microinject a DNA/DOTAP mixture into eyebuds of one day old Xenopus laevis embryos, and how to image and reconstruct individual green fluorescent protein (GFP) expressing optic axonal arbors in tectal midbrains of intact, living Xenopus tadpoles.

Mikroinjektion von DNA in Augenknospen in Xenopus laevis Embryonen und Bildgebung von GFP Expressing Optic Axonal Arbors in Intact, Living Xenopus Tadpoles

The primary visual projection of tadpoles of the aquatic frog Xenopus laevis serves as an excellent model system for studying mechanisms that regulate the ...

Entwicklungsbiologie

Flat Mount Imaging of Mouse Skin and Its Application to the Analysis of Hair Follicle Patterning and Sensory Axon Morphology

Skin is a highly heterogeneous tissue. Intra-dermal structures include hair follicles, arrector pili muscles, epidermal specializations (such as Merkel cell clusters), sebaceous glands, nerves and nerve endings, and capillaries. The spatial arrangement of these structures is tightly controlled on a microscopic scale - as seen, for example, in the orderly arrangement of cell types within a single hair follicle - and on a macroscopic scale - as seen by the nearly identical orientations of thousands of hair follicles within a local region of skin. Visualizing these structures without physically sectioning the skin is possible because of the 2-dimensional geometry of this organ. In this protocol, we show that mouse skin can be dissected, fixed, permeabilized, stained, and clarified as an intact two dimensional object, a flat mount. The protocol allows for easy visualization of skin structures in their entirety through the full thickness of large areas of skin by optical sectioning and reconstruction. Images of these structures can also be integrated with information about position and orientation relative to the body axes.

Mammalian skin contains a diverse array of structures - such as hair follicles and nerve endings - that exhibit distinctive patterns of spatial organization. Analyzing skin as a flat mount takes advantage of the 2-dimensional geometry of this tissue to produce full-thickness high-resolution images of skin structures.

Wohnung Berg-Imaging von Mäusehaut und ihre Anwendung auf die Analyse von Mustern und die Haarfollikel Sinnes Axon Morphologie

Skin is a highly heterogeneous tissue. Intra-dermal structures include hair follicles, arrector pili muscles, epidermal specializations (such as Merkel ...

Three and Four-Dimensional Visualization and Analysis Approaches to Study Vertebrate Axial Elongation and Segmentation

Somitogenesis is a hallmark of vertebrate embryonic development. For years, researchers have been studying this process in a variety of organisms using a wide range of techniques encompassing ex vivo and in vitro approaches. However, most studies still rely on the analysis of two-dimensional (2D) imaging data, which limits proper evaluation of a developmental process like axial extension and somitogenesis involving highly dynamic interactions in a complex 3D space. Here we describe techniques that allow mouse live imaging acquisition, dataset processing, visualization and analysis in 3D and 4D to study the cells (e.g., neuromesodermal progenitors) involved in these developmental processes. We also provide a step-by-step protocol for optical projection tomography and whole-mount immunofluorescence microscopy in mouse embryos (from sample preparation to image acquisition) and show a pipeline that we developed to process and visualize 3D image data. We extend the use of some of these techniques and highlight specific features of different available software (e.g., Fiji/ImageJ, Drishti, Amira and Imaris) that can be used to improve our current understanding of axial extension and somite formation (e.g., 3D reconstructions). Altogether, the techniques here described emphasize the importance of 3D data visualization and analysis in developmental biology, and might help other researchers to better address 3D and 4D image data in the context of vertebrate axial extension and segmentation. Finally, the work also employs novel tools to facilitate teaching vertebrate embryonic development.

Here, we describe computational tools and methods that allow visualization and analysis of three and four-dimensional image data of mouse embryos in the context of axial elongation and segmentation, obtained by in toto optical projection tomography, and by live imaging and whole-mount immunofluorescence staining using multiphoton microscopy.

Drei- und vierdimensionale Visualisierungs- und Analyseansätze zur Untersuchung der axialen Dehnung und Segmentierung von Wirbeltieren

Somitogenesis is a hallmark of vertebrate embryonic development. For years, researchers have been studying this process in a variety of organisms using a ...

Visualization of the Axonal Projection Pattern of Embryonic Motor Neurons in Drosophila

The establishment of functional neuromuscular circuits relies on precise connections between developing motor axons and target muscles. Motor neurons extend growth cones to navigate along specific pathways by responding to a large number of axon guidance cues that emanate from the surrounding extracellular environment. Growth cone target recognition also plays a critical role in neuromuscular specificity. This work presents a standard immunohistochemistry protocol to visualize motor neuron projections of late stage-16 Drosophila melanogaster embryos. This protocol includes a few key steps, including a genotyping procedure, to sort the desired mutant embryos; an immunostaining procedure, to tag embryos with fasciclin II (FasII) antibody; and a dissection procedure, to generate filleted preparations from fixed embryos. Motor axon projections and muscle patterns in the periphery are much better visualized in flat preparations of filleted embryos than in whole-mount embryos. Therefore, the filleted preparation of fixed embryos stained with FasII antibody provides a powerful tool to characterize the genes required for motor axon pathfinding and target recognition, and it can also be applied to both loss-of-function and gain-of-function genetic screens.

Visualization of the Axonal Projection Pattern of Embryonic Motor Neurons in Drosophila

This work details a standard immunohistochemistry method to visualize motor neuron projections of late stage-16 Drosophila melanogaster embryos. The filleted preparation of fixed embryos stained with FasII antibody provides a powerful tool to characterize the genes required for motor axon pathfinding and target recognition during neural development.

Visualisierung des axonalen Projektionsmusters der embryonalen motorischen Neuronen in<em&gt; Drosophila</em

The establishment of functional neuromuscular circuits relies on precise connections between developing motor axons and target muscles. Motor neurons ...

Visualization of Motor Axon Navigation and Quantification of Axon Arborization In Mouse Embryos Using Light Sheet Fluorescence Microscopy

Spinal motor neurons (MNs) extend their axons to communicate with their innervating targets, thereby controlling movement and complex tasks in vertebrates. Thus, it is critical to uncover the molecular mechanisms of how motor axons navigate to, arborize, and innervate their peripheral muscle targets during development and degeneration. Although transgenic Hb9::GFP mouse lines have long served to visualize motor axon trajectories during embryonic development, detailed descriptions of the full spectrum of axon terminal arborization remain incomplete due to the pattern complexity and limitations of current optical microscopy. Here, we describe an improved protocol that combines light sheet fluorescence microscopy (LSFM) and robust image analysis to qualitatively and quantitatively visualize developing motor axons. This system can be easily adopted to cross genetic mutants or MN disease models with Hb9::GFP lines, revealing novel molecular mechanisms that lead to defects in motor axon navigation and arborization.

Here, we describe a protocol for visualizing motor neuron projection and axon arborization in transgenic Hb9::GFP mouse embryos. After immunostaining for motor neurons, we used light sheet fluorescence microscopy to image embryos for subsequent quantitative analysis. This protocol is applicable to other neuron navigation processes in the central nervous system.

Visualisierung von motorischen Axon Navigation und Quantifizierung der Axon Arborization In Mausembryonen mit Fluoreszenz-Lichtblattmikroskopie

Spinal motor neurons (MNs) extend their axons to communicate with their innervating targets, thereby controlling movement and complex tasks in ...

Large-scale Three-dimensional Imaging of Cellular Organization in the Mouse Neocortex

The mammalian neocortex is composed of many types of excitatory and inhibitory neurons, each with specific electrophysiological and biochemical properties, synaptic connections, and in vivo functions, but their basic functional and anatomical organization from cellular to network scale is poorly understood. Here we describe a method for the three-dimensional imaging of fluorescently-labeled neurons across large areas of the brain for the investigation of the cortical cellular organization. Specific types of neurons are labeled by the injection of fluorescent retrograde neuronal tracers or expression of fluorescent proteins in transgenic mice. Block brain samples, e.g., a hemisphere, are prepared after fixation, made transparent with tissue clearing methods, and subjected to fluorescent immunolabeling of the specific cell types. Large areas are scanned using confocal or two-photon microscopes equipped with large working distance objectives and motorized stages. This method can resolve the periodic organization of the cell type-specific microcolumn functional modules in the mouse neocortex. The procedure can be useful for the study of three-dimensional cellular architecture in the diverse brain areas and other complex tissues.

Here we describe a procedure for tissue clearing, fluorescent labeling, and large-scale imaging of mouse brain tissue which, thereby, enables visualization of the three-dimensional organization of cell types in the neocortex.

Groß angelegte dreidimensionale Bildgebung der zelluläre Organisation in der Maus Neocortex

The mammalian neocortex is composed of many types of excitatory and inhibitory neurons, each with specific electrophysiological and biochemical ...

Visualisierung der Dynamik von neuronalen und glialen Zellen im sich entwickelnden Gehirn von Mäusen

Time-Lapse Imaging of Migrating Neurons and Glial Progenitors in Embryonic Mouse Brain Slices

During the development of the cerebral cortex, neurons and glial cells originate in the ventricular zone lining the ventricle and migrate toward the brain surface. This process is crucial for proper brain function, and its dysregulation can result in neurodevelopmental and psychiatric disorders after birth. In fact, many genes responsible for these diseases have been found to be involved in this process, and therefore, revealing how these mutations affect cellular dynamics is important for understanding the pathogenesis of these diseases. This protocol introduces a technique for time-lapse imaging of migrating neurons and glial progenitors in brain slices obtained from mouse embryos. Cells are labeled with fluorescent proteins using in utero electroporation, which visualizes individual cells migrating from the ventricular zone with a high signal-to-noise ratio. Moreover, this in vivo gene transfer system enables us to easily perform gain-of-function or loss-of-function experiments on the given genes by co-electroporation of their expression or knockdown/knockout vectors. Using this protocol, the migratory behavior and migration speed of individual cells, information that is never obtained from fixed brains, can be analyzed.

Autor im Rampenlicht: Erforschung der Zellmigration und der Rolle der Gene im sich entwickelnden Gehirn

During the development of the cerebral cortex, neurons and glial cells originate in the ventricular zone lining the ventricle and migrate toward the brain surface. Many genes are involved in this process. This protocol introduces the technique for the time-lapse imaging of migrating neurons and glial progenitors.

Zeitraffer-Bildgebung von migrierenden Neuronen und glialen Vorläuferzellen in embryonalen Hirnschnitten von Mäusen

During the development of the cerebral cortex, neurons and glial cells originate in the ventricular zone lining the ventricle and migrate toward the brain ...