We thank Monika Kilchenmann, Federica Bisignani and Agathe Duda for their excellent technical assistance.

Toutes les expériences ont adhéré à la Déclaration de l&#39;utilisation d&#39;animaux dans ophtalmique et Vision Research de l&#39;Association pour la recherche en vision et en ophtalmologie (ARVO). 1. Animaux <ol><li> Maintenir le poisson zèbre de type sauvage (Danio rerio) de la souche AB (Oregon) âgés de 6-12 mois dans des conditions standard dans l&#39;eau avec une température de 26,5 ° C et un 14/10 h cycle lumière / obscurité 15. </li><li> Suivez les directives de protection des animaux des établissements concernés pour les expériences sur les animaux après l&#39;approbation par l&#39;Office vétérinaire cantonal. </li></ol> 2. Traitement MNU <ol><li> Préparez de l&#39;eau contenant 150 mg / L de matière sèche de la N -nitrosourea de N (MNU). ATTENTION! MNU est toxique; peut causer le cancer, des dommages génétiques héréditaires ou néfastes pour l&#39;enfant à naître. </li><li> Incuber le poisson-zèbre dans de l&#39;eau contenant le MNU pendant 60 min à température ambiante. </li><li> Rincez le poisson zèbre rapidement avecl&#39;eau douce et de mettre le poisson à un nouveau réservoir de poissons sans MNU. Maintenir le poisson dans des conditions standard aussi longtemps que désiré pour les expériences. </li></ol> 3. acuité mesure <ol><li> Démarrez le système optomoteur, choisissez «testing» dans le menu et définissez les options pour &quot;Escalier simple», «Acuity (Freq)» et «randomisés / indépendante» 16. </li><li> Installez une bouteille de perfusion remplie de 500 ml d&#39;eau environ 1 m au-dessus du système de optomoteur. </li><li> Placez un poisson zèbre dans la chambre d&#39;examen et le connecter à la bouteille de perfusion. Placer la chambre d&#39;examen dans le système optomoteur. </li><li> Lancer la mesure et observer le mouvement de l&#39;œil en temps réel sur l&#39;écran de l&#39;ordinateur. Ainsi, une réponse positive (&quot;oui&quot;) est défini comme saccades consécutives dans le bon sens, alors qu&#39;une réponse négative («non») représente les mouvements aléatoires des yeux semblables à ceux observés avec la stationréseaux aires. Si les yeux de l&#39;exposition du poisson zèbre trois ou plusieurs réponses optocinétiques ultérieures (OKR), appuyez sur «oui»; sinon, appuyez sur «non». </li><li> Extrait de l&#39;acuité visuelle, qui a été calculé par le logiciel en déterminant le seuil de la fréquence spatiale de la stimulation optocinétique, dans &quot;Résultats&quot; dans le menu. </li></ol> 4. histologie <ol><li> Euthanasier le poisson zèbre par une surdose d&#39;éthyle 3-aminobenzoate méthanesulfonate (2-300 mg / L) et énucléer les yeux. </li><li> Fixer les yeux entiers dans 4% de paraformaldehyde (PFA) dans une solution saline tamponnée au phosphate (PBS) à 4 ° C pendant 12 heures et ensuite déshydrater les échantillons dans une série graduée d&#39;alcool. </li><li> Intégrer les échantillons dans de la paraffine, couper 5 um sections à travers la tête du nerf optique (TNO) et les monter sur une lame de verre. </li><li> Colorer les coupes de paraffine deparaffized avec Hémalun pendant 4 min et plongez les lames deux fois à l&#39;eau distillée puis de 0,2% aci chlorhydriqued et 0,8% d&#39;ammoniac. Colorer les sections avec de l&#39;éosine pour 3 mn après le développement de la coloration à l&#39;hémalun dans l&#39;eau du robinet pendant au moins 10 min (H &amp; E). </li><li> Intégrer les diapositives déshydratés dans un milieu de montage et d&#39;observer les lames au microscope optique. </li></ol> 5. immunohistochimie <ol><li> Désoxynucléotidyltransférase Terminal dUTP nick étiquetage de fin (TUNEL) <ol><li> Incuber les sections déparaffinées avec 20 ug / ml de protéinase K à la température ambiante pendant 15 min. Laver les sections trois fois avec une solution saline tamponnée Tris (TBS) pendant 5 minutes chacun. </li><li> Incuber les sections du mélange de réaction de 50 ul TUNEL (marquage de la solution de 10% et une solution d&#39;enzyme à 90%) dans une chambre humidifiée à 37 ° C pendant 60 min. Laver trois fois avec du TBS pendant 5 minutes chacun. </li><li> Monter les lames avec un milieu contenant DAPI de montage et d&#39;observer les lames au microscope à fluorescence. </li></ol></li><li> Cellulaire antigène nucléaire (PCNA) coloration <ol><li> Faire bouillir les sections déparaffinées dans du tampon de récupération d&#39;antigène (Tris-EDTA + 0,05% de Tween 20, pH 9,0) pendant 3 minutes et laver trois fois avec du TBS pendant 5 minutes chacun. Bloquer avec 100 ul de solution (TBS + 10% sérum de chèvre + 1% d&#39;albumine de sérum de bovin normal, pH 7,6) à la température ambiante pendant 1 heure blocage. </li><li> Colorer avec des anticorps primaires anti-PCNA dans une dilution 1: 200 dans une chambre humidifiée à 4 ° C pendant une nuit. Laver trois fois avec du TBS + Tween 20 pendant 5 minutes chacun. </li><li> Terminer la détection avec des anticorps secondaires appropriés à une dilution de 1: 500 à température ambiante pendant 1 heure. </li><li> Monter les lames avec un milieu contenant DAPI de montage et d&#39;observer les lames au microscope à fluorescence. </li></ol></li></ol>

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M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+quantification+of+adult+and+developing+mouse+spatial+vision+using+a+virtual+optomotor+system.">Rapid quantification of adult and developing mouse spatial vision using a virtual optomotor system.</a> Invest. Ophthalmol Vis. Sci. 45 (12), 4611-4616 (2004).</li><li>Beck, J. C., Gilland, E., Tank, D. W., Baker, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantifying+the+ontogeny+of+optokinetic+and+vestibulo-ocular+behaviors+in+zebrafish,+medaka,+and+goldfish.">Quantifying the ontogeny of optokinetic and vestibulo-ocular behaviors in zebrafish, medaka, and goldfish.</a> J. Neurophysiol. 92 (6), 3546-3561 (2004).</li><li>Fimbel, S. M., Montgomery, J. E., Burket, C. T., Hyde, D. 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The authors have nothing to disclose.

Auparavant, notre groupe a transféré le modèle MNU de dégénérescence des photorécepteurs de rongeurs dans le système poisson-zèbre 9. Les événements qui ont suivi ont été décrits et suivis pendant 30 jours. En cette période de dégénérescence rétinienne morphologique complet et la régénération se sont produits après le traitement initial. Tout d&#39;abord, l&#39;histologie révèle une cellule de tige réduite compter du jour 3 avec un minimum à jour 8 En conséquence, la coloration TUN...

Vision est le sens le plus essentiel pour l&#39;être humain et sa dépréciation a un impact socio-économique élevé. Dans le monde développé, les maladies dégénératives de la rétine sont la principale cause de perte de vision et de cécité chez les personnes âgées 1. La cause de la plupart des maladies dégénératives de la rétine n&#39;est que partiellement comprise et solutions thérapeutiques pour retrouver la vision perdue sont très limitées. La rétinite pigmentaire est un exemple typique d&#39;une maladie dégénérative de la rétine avec une perte des photorécepteurs primaire 2-3. N-méthyl-N -nitrosourea (MNU) induit la dégénérescence rétinienne et est donc largement utilisée chez les rongeurs pour modéliser les maladies avec photorécepteur primaire mort cellulaire 4. Il s&#39;agit d&#39;un agent d&#39;alkylation et conduit à des tumeurs bénignes et malignes, qui apparaissent habituellement plusieurs mois après l&#39;exposition 7.5. En outre, il provoque photorécepteur spécifique de mort cellulaire dans une période d&#39;observation de courte durée. De ce fait, la perte de la couche rétinienne structure et l&#39;amincissement de la rétine significative a été observée d&#39;une manière dépendante de la concentration. Les cellules gliales de la rétine ont été activés, mais aucun changement dans l&#39;épithélium pigmentaire rétinien (EPR) ont été trouvés. Réticulum endoplasmique (ER) de l&#39;apoptose liée au stress semble être la principale voie d&#39;action MNU dans la rétine 8. Nous avons récemment introduit MNU comme un modèle chimique pour induire une dégénérescence des photorécepteurs chez le poisson zèbre 9. Parmi d&#39;autres raisons, le poisson zèbre (Danio rerio) a pris de l&#39;importance dans la recherche visuelle en raison des similitudes de son système visuel à celle des autres vertébrés 10. La rétine externe contient les photorécepteurs, qui peuvent être regroupés en quatre types de cônes différents avec des sensibilités de pointe dans l&#39;ultraviolet, à court, moyen et à long longueur d&#39;onde du spectre visible et une tige type de photorécepteur. Dans la couche nucléaire interne (INL), les corps cellulaires des bipolaires, horizontales et amacrines interneurones se trouvent, comme well en tant que corps cellulaire des cellules gliales Muller. Dans la couche plexiforme externe (OPL) des contacts synaptiques entre les photorécepteurs et la rétine interne sont formées, tandis que la couche cellulaire la plus proche de la lentille est la couche des cellules ganglionnaires (GC), les composants qui forment de longs axones comprenant le nerf optique et la bandelette optique . Des contacts synaptiques entre les cellules ganglionnaires et les cellules de la couche nucléaire interne sont formées dans la couche plexiforme interne (IPL) 11. L&#39;EPR est en dehors de la rétine neurosensorielle et entoure les segments externes des photorécepteurs avec longues microvillosités apicale 12. En outre, le poisson zèbre est très régénérative et en mesure de repousser cerveau lésé, la rétine, la moelle épinière, le cœur et d&#39;autres tissus 13. Lorsque se produit une lésion rétinienne, les cellules dans la INL, qui l&#39;on pense être les cellules de Müller, sont activés et ont le potentiel de se différencier en différents types de cellules rétiniennes. De plus, ils produisent également des progéniteurs de la tige, qui sont situés dans l&#39;ONL. Une autre manièreurce qui fournit la rétine de poisson zèbre adulte avec de nouvelles cellules est la zone marginale ciliaire. Cette source est nécessaire pour obtenir une densité constante de photorécepteurs de la tige dans le poisson zèbre œil croissance continue 14. La MNU modèle peut être utilisé comme une approche simple et reproductible dégénérescence / régénération de tissu rétinien. En raison de certaines similitudes entre les processus biologiques chez le poisson zèbre et chez l&#39;homme ce qui pourrait ouvrir les portes à identifier impliqués voies de mort cellulaire et de cribler des médicaments potentiellement neuroprotecteurs. Basé sur une étude précédente de notre groupe, nous illustrons maintenant les méthodes de ce modèle de poisson zèbre MNU induite par ment de la rétine et la régénération conséquente y compris les changements fonctionnels avec selon laboratoire vidéos 9.

<table border="0" cellpadding="0" cellspacing="0" >
	<tbody>
		<tr >
			<td >Acetic acid</td>
			<td>Sigma-Aldrich, Buchs, Switzerland</td>
			<td>A6283</td>
			<td></td>
		</tr>
		<tr >
			<td >Ammonia</td>
			<td>Sigma-Aldrich, Buchs, Switzerland</td>
			<td>294993</td>
			<td>0.80%</td>
		</tr>
		<tr >
			<td >Bovine serum albumine (BSA)</td>
			<td>Sigma-Aldrich, Buchs, Switzerland</td>
			<td>05470</td>
			<td></td>
		</tr>
		<tr >
			<td >Dako Pen</td>
			<td>Dako, Glostrup, Danmark</td>
			<td>S2002</td>
			<td></td>
		</tr>
		<tr >
			<td >DAPI mounting medium</td>
			<td>Vector Labs, Burlingame, CA, USA</td>
			<td>H-1200</td>
			<td></td>
		</tr>
		<tr >
			<td >Eosin</td>
			<td>Sigma-Aldrich, Buchs, Switzerland</td>
			<td>45260</td>
			<td></td>
		</tr>
		<tr >
			<td >Ethanol</td>
			<td>Sigma-Aldrich, Buchs, Switzerland</td>
			<td>2860</td>
			<td>100%, 96%, 70%</td>
		</tr>
		<tr >
			<td >Ethylenediaminetetraacetic acid (EDTA)</td>
			<td>Sigma-Aldrich, Buchs, Switzerland</td>
			<td>ED</td>
			<td></td>
		</tr>
		<tr >
			<td >Ethyl 3-aminobenzoate methanesulfonate salt</td>
			<td>Sigma-Aldrich, Buchs, Switzerland</td>
			<td>E10521</td>
			<td>Tricaine</td>
		</tr>
		<tr >
			<td >Eukitt</td>
			<td>Sigma-Aldrich, Buchs, Switzerland</td>
			<td>3989</td>
			<td></td>
		</tr>
		<tr >
			<td >Goat anti-rabbit Alexa 594</td>
			<td>Life Technologies, Zug, Switzerland</td>
			<td>A11012</td>
			<td></td>
		</tr>
		<tr >
			<td >Goat normal serum</td>
			<td>Dako, Glostrup, Danmark</td>
			<td>X0907</td>
			<td></td>
		</tr>
		<tr >
			<td >Hydrochloric acid</td>
			<td>Sigma-Aldrich, Buchs, Switzerland</td>
			<td>320331</td>
			<td>0.20%</td>
		</tr>
		<tr >
			<td >In situ Cell Death Detection Kit</td>
			<td>Roche Applied Sciences, Rotkreuz, Switzerland</td>
			<td>11684795910</td>
			<td>TUNEL Kit</td>
		</tr>
		<tr >
			<td >Mayer&#39;s hemalum solution</td>
			<td>Merck, Darmstadt, Germany</td>
			<td>109249</td>
			<td></td>
		</tr>
		<tr >
			<td >Methylnitrosourea (MNU)</td>
			<td>Sigma-Aldrich, Buchs, Switzerland</td>
			<td>N4766</td>
			<td>Toxic</td>
		</tr>
		<tr >
			<td >OptoMotry</td>
			<td>CerebralMechanics, Lethbridge, AB, Canada</td>
			<td>n.a.</td>
			<td></td>
		</tr>
		<tr >
			<td >Paraformaldehyde (PFA)</td>
			<td>Sigma-Aldrich, Buchs, Switzerland</td>
			<td>P6148</td>
			<td></td>
		</tr>
		<tr >
			<td >Phosphate buffered saline (PBS)</td>
			<td>Sigma-Aldrich, Buchs, Switzerland</td>
			<td>P5368</td>
			<td></td>
		</tr>
		<tr >
			<td >Proteinase K</td>
			<td>Dako, Glostrup, Danmark</td>
			<td>S3004</td>
			<td></td>
		</tr>
		<tr >
			<td >Rabbit anti-PCNA</td>
			<td>Santa Cruz Biotechnology, Santa Cruz, USA</td>
			<td>sc-33756</td>
			<td></td>
		</tr>
		<tr >
			<td >Superfrost Plus glass slides</td>
			<td>Gehard Menzel GmbH, Braunschweig, Germany</td>
			<td>10149870</td>
			<td></td>
		</tr>
		<tr >
			<td >Tris buffered saline (TBS)</td>
			<td>Sigma-Aldrich, Buchs, Switzerland</td>
			<td>P5912</td>
			<td></td>
		</tr>
		<tr >
			<td >Trizma&#210; base</td>
			<td>Sigma-Aldrich, Buchs, Switzerland</td>
			<td>T1503</td>
			<td></td>
		</tr>
		<tr >
			<td >Tween 20</td>
			<td>Sigma-Aldrich, Buchs, Switzerland</td>
			<td>P1379</td>
			<td></td>
		</tr>
		<tr >
			<td >Xylene</td>
			<td>Sigma-Aldrich, Buchs, Switzerland</td>
			<td>534056</td>
			<td></td>
		</tr>
		<tr >
			<td >Zebrafish (Danio rerio) AB (Oregon) strain</td>
			<td>University of Fribourg, Dept. of Biology</td>
			<td>n.a.</td>
			<td>Own fish facility</td>
		</tr>
	</tbody>
</table>

methylnitrosourea (mnu)-induced retinal degeneration and regeneration in the zebrafish: histological and functional characteristics

Maladies dégénératives de la rétine, par exemple, la rétinite pigmentaire, avec des dommages de photorécepteur compte résultant pour la plupart de la perte de vision dans le monde industriel. Les modèles animaux sont d&#39;une importance cruciale pour étudier ces maladies. À cet égard, la toxine spécifique photorécepteur N de -nitrosourea de N (MNU) a été largement utilisé chez les rongeurs pour induire pharmacologiquement dégénérescence rétinienne. Auparavant, nous avons établi un modèle de dégénérescence rétinienne MNU-induite chez le poisson zèbre, un autre système de modèle populaire dans la recherche visuelle. Une différence fascinant pour les mammifères est la neurogenèse persistante chez l&#39;adulte rétine de poisson zèbre et sa régénération après une lésion. Pour quantifier cette observation, nous avons utilisé des mesures de l&#39;acuité visuelle chez le poisson zèbre adulte. De ce fait, le réflexe optocinétique a été utilisé pour suivre les changements fonctionnels chez les poissons non-anesthésié. Ceci a été complété par l&#39;histologie ainsi que staini immunohistochimiqueng de l&#39;apoptose (TUNEL) et la prolifération (PCNA) afin de corréler les changements morphologiques en développement. En résumé, l&#39;apoptose des photorécepteurs se produit trois jours après le traitement MNU, qui est suivie par une réduction marquée de cellules dans la couche nucléaire externe (ONL). Par la suite, la prolifération des cellules de la couche nucléaire interne (INL) et ONL est observée. Ici, nous révélons que non seulement une complète histologique mais aussi une régénération fonctionnelle se produit sur un parcours de temps de 30 jours. Maintenant, nous illustrons les méthodes de quantification et le suivi ment de la rétine de poisson zèbre et la régénération utilisant MNU dans une vidéo au format.

Acuité visuelle: Le dispositif expérimental [de fréquence spatiale: 0.042 cercles / degré (c / d); contraste: 100%; vitesse de dérive: 20 degrés / seconde (d / src); retour luminance lumineuse: 152 cd / m 2] de cette étude a permis évaluation Oberkirchenrätin de poisson zèbre adulte. La durée moyenne de mesure VA était d&#39;environ 5 - 10 minutes pour chaque poisson zèbre, qui bien toléré la procédure. L&#39;acuité visuelle avant l&#39;exposition MNU était 0,577...

Watch this Scientific Journal Video about Methylnitrosourea MNU-induced Retinal Degeneration and Regeneration in the Zebrafish: Histological and Functional Characteristics at JoVE.com

Methylnitrosourea MNU-induced Retinal Degeneration and Regeneration in the Zebrafish: Histological and Functional Characteristics

Ici, nous démontrons la quantification des ment de la rétine et de la régénération et de son impact sur ​​la fonction visuelle en utilisant la N -nitrosourea de N chez le poisson zèbre adulte. Baisse de l&#39;acuité visuelle et une diminution du nombre de photorécepteurs ont été suivis par une prolifération dans la couche nucléaire interne. Régénération morphologique et fonctionnelle complète a eu lieu 30 jours après le traitement initial.

Méthylnitrosourée (MNU) induite par dégénérescence rétinienne et la régénération dans le poisson zèbre: caractéristiques histologiques et fonctionnelles

Retinal degenerative diseases, e.g. retinitis pigmentosa, with resulting photoreceptor damage account for the majority of vision loss in the industrial ...

methylnitrosourea-mnu-induced-retinal-degeneration-regeneration

Research

JoVE Journal

Biology

Methylnitrosourea (MNU)-induced Retinal Degeneration and Regeneration in the Zebrafish: Histological and Functional Characteristics

11.4K vues.  University of Bern.  Ici, nous démontrons la quantification des ment de la rétine et de la régénération et de son impact sur ​​la fonction visuelle en utilisant la N -nitrosourea de N chez le poisson zèbre adulte. Baisse de l'acuité visuelle et une diminution du nombre de photorécepteurs ont été suivis par une prolifération dans la couche nucléaire interne. Régénération morphologique et fonctionnelle complète a eu lieu 30 jours après le traitement i...

Vidéo: Methylnitrosourea MNU-induced Retinal Degeneration and Regeneration in the Zebrafish: Histological and Functional Characteristics

Laser Ablation of the Zebrafish Pronephros to Study Renal Epithelial Regeneration

Acute kidney injury (AKI) is characterized by high mortality rates from deterioration of renal function over a period of hours or days that culminates in renal failure1. AKI can be caused by a number of factors including ischemia, drug-based toxicity, or obstructive injury1. This results in an inability to maintain fluid and electrolyte homeostasis. While AKI has been observed for decades, effective clinical therapies have yet to be developed. Intriguingly, some patients with AKI recover renal functions over time, a mysterious phenomenon that has been only rudimentally characterized1,2. Research using mammalian models of AKI has shown that ischemic or nephrotoxin-injured kidneys experience epithelial cell death in nephron tubules1,2, the functional units of the kidney that are made up of a series of specialized regions (segments) of epithelial cell types3. Within nephrons, epithelial cell death is highest in proximal tubule cells. There is evidence that suggests cell destruction is followed by dedifferentiation, proliferation, and migration of surrounding epithelial cells, which can regenerate the nephron entirely1,2. However, there are many unanswered questions about the mechanisms of renal epithelial regeneration, ranging from the signals that modulate these events to reasons for the wide variation of abilities among humans to regenerate injured kidneys.
The larval zebrafish provides an excellent model to study kidney epithelial regeneration as its pronephric kidney is comprised of nephrons that are conserved with higher vertebrates including mammals4,5. The nephrons of zebrafish larvae can be visualized with fluorescence techniques because of the relative transparency of the young zebrafish6. This provides a unique opportunity to image cell and molecular changes in real-time, in contrast to mammalian models where nephrons are inaccessible because the kidneys are structurally complex systems internalized within the animal. Recent studies have employed the aminoglycoside gentamicin as a toxic causative agent for study of AKI and subsequent renal failure: gentamicin and other antibiotics have been shown to cause AKI in humans, and researchers have formulated methods to use this agent to trigger kidney damage in zebrafish7,8. However, the effects of aminoglycoside toxicity in zebrafish larvae are catastrophic and lethal, which presents a difficulty when studying epithelial regeneration and function over time. Our method presents the use of targeted cell ablation as a novel tool for the study of epithelial injury in zebrafish. Laser ablation gives researchers the ability to induce cell death in a limited population of cells. Varying areas of cells can be targeted based on morphological location, function, or even expression of a particular cellular phenotype. Thus, laser ablation will increase the specificity of what researchers can study, and can be a powerful new approach to shed light on the mechanisms of renal epithelial regeneration. This protocol can be broadly applied to target cell populations in other organs in the zebrafish embryo to study injury and regeneration in any number of contexts of interest.

Acute kidney injury (AKI) in humans is a common clinical problem caused by damage to the epithelial cells that comprise kidney nephrons, and AKI is associated with high mortality rates of 50-70%1. Following epithelial cell destruction, nephrons have a limited ability to regenerate, though the mechanisms and limitations that guide this phenomenon remain poorly understood. In this video article, we describe our technique for targeted laser ablation of kidney nephron cells in the zebrafish embryo kidney, or pronephros. Our new method can be used to complement nephrotoxicity-induced models of AKI and gain a high-resolution understanding of the cell and molecular alterations that are associated with epithelial regeneration in the kidney nephron.

Laser Ablation de l&#39;pronéphros Zebrafish d&#39;étude rénale régénération épithéliale

Acute kidney injury (AKI) is characterized by high mortality rates from deterioration of renal function over a period of hours or days that culminates in ...

Recherche

Biologie

Pharmacological and Functional Genetic Assays to Manipulate Regeneration of the Planarian Dugesia japonica

Free-living planarian flatworms have a long history of experimental usage owing to their remarkable regenerative abilities1. Small fragments excised from these animals reform the original body plan following regeneration of missing body structures. For example if a 'trunk' fragment is cut from an intact worm, a new 'head' will regenerate anteriorly and a 'tail' will regenerate posteriorly restoring the original 'head-to-tail' polarity of body structures prior to amputation (Figure 1A).
Regeneration is driven by planarian stem cells, known as 'neoblasts' which differentiate into ~30 different cell types during normal body homeostasis and enforced tissue regeneration. This regenerative process is robust and easy to demonstrate. Owing to the dedication of several pioneering labs, many tools and functional genetic methods have now been optimized for this model system. Consequently, considerable recent progress has been made in understanding and manipulating the molecular events underpinning planarian developmental plasticity2-9.
The planarian model system will be of interest to a broad range of scientists. For neuroscientists, the model affords the opportunity to study the regeneration of an entire nervous system, rather than simply the regrowth/repair of single nerve cell process that typically are the focus of study in many established models. Planarians express a plethora of neurotransmitters10, represent an important system for studying evolution of the central nervous system11, 12 and have behavioral screening potential13, 14. 
Regenerative outcomes are amenable to manipulation by pharmacological and genetic apparoaches. For example, drugs can be screened for effects on regeneration simply by placing body fragments in drug-containing solutions at different time points after amputation. The role of individual genes can be studied using knockdown methods (in vivo RNAi), which can be achieved either through cycles of microinjection or by feeding bacterially-expressed dsRNA constructs8, 9, 15. Both approaches can produce visually striking phenotypes at high penetrance- for example, regeneration of bipolar animals16-21. To facilitate adoption of this model and implementation of such methods, we showcase in this video article protocols for pharmacological and genetic assays (in vivo RNAi by feeding) using the planarian Dugesia japonica.

Pharmacological and Functional Genetic Assays to Manipulate Regeneration of the Planarian Dugesia japonica

An attractive model for studying stem cell differentiation within a live animal is the planarian flatworm. Regeneration is studied by simple amputation experiments that are easily performed in a basic laboratory and are amenable to pharmacological and genetic (in vivo RNAi) manipulation as detailed by protocols in this article.

Pharmacologiques et des essais de génétique pour manipuler la régénération de l&#39;Planaires Japonica Dugesia</em

Free-living planarian flatworms have a long history of experimental usage owing to their remarkable regenerative abilities1. Small fragments excised from ...

In vivo Electroporation of Morpholinos into the Adult Zebrafish Retina

Many devastating inherited eye diseases result in progressive and irreversible blindness because humans cannot regenerate dying or diseased retinal neurons. In contrast, the adult zebrafish retina possesses the robust ability to spontaneously regenerate any neuronal class that is lost in a variety of different retinal damage models, including retinal puncture, chemical ablation, concentrated high temperature, and intense light treatment 1-8. Our lab extensively characterized regeneration of photoreceptors following constant intense light treatment and inner retinal neurons after intravitreal ouabain injection 2, 5, 9. In all cases, resident M&uuml;ller glia re-enter the cell cycle to produce neuronal progenitors, which continue to proliferate and migrate to the proper retinal layer, where they differentiate into the deficient neurons. 
	We characterized five different stages during regeneration of the light-damaged retina that were highlighted by specific cellular responses. We identified several differentially expressed genes at each stage of retinal regeneration by mRNA microarray analysis 10. Many of these genes are also critical for ocular development. To test the role of each candidate gene/protein during retinal regeneration, we needed to develop a method to conditionally limit the expression of a candidate protein only at times during regeneration of the adult retina. 
	Morpholino oligos are widely used to study loss of function of specific proteins during the development of zebrafish, Xenopus, chick, mouse, and tumors in human xenografts 11-14. These modified oligos basepair with complementary RNA sequence to either block the splicing or translation of the target RNA. Morpholinos are stable in the cell and can eliminate or "knockdown" protein expression for three to five days 12. 
	Here, we describe a method to efficiently knockdown target protein expression in the adult zebrafish retina. This method employs lissamine-tagged antisense morpholinos that are injected into the vitreous of the adult zebrafish eye. Using electrode forceps, the morpholino is then electroporated into all the cell types of the dorsal and central retina. Lissamine provides the charge on the morpholino for electroporation and can be visualized to assess the presence of the morpholino in the retinal cells. 
	Conditional knockdown in the retina can be used to examine the role of specific proteins at different times during regeneration. Additionally, this approach can be used to study the role of specific proteins in the undamaged retina, in such processes as visual transduction and visual processing in second order neurons.

In vivo Electroporation of Morpholinos into the Adult Zebrafish Retina

A method to conditionally knockdown a target protein&#x2019;s expression in the adult zebrafish retina is described, which involves intravitreally injecting antisense morpholinos and electroporating them into the retina. The resulting protein is knocked down for several days, which allows testing the protein&#x2019;s role in the regenerating or intact retina.

En électroporation in vivo de morpholinos dans la rétine de poisson zèbre adulte

Many devastating inherited eye diseases result in progressive and irreversible blindness because humans cannot regenerate dying or diseased retinal ...

In vivo Electroporation of Morpholinos into the Regenerating Adult Zebrafish Tail Fin

Certain species of urodeles and teleost fish can regenerate their tissues. Zebrafish have become a widely used model to study the spontaneous regeneration of adult tissues, such as the heart1, retina2, spinal cord3, optic nerve4, sensory hair cells5, and fins6.
The zebrafish fin is a relatively simple appendage that is easily manipulated to study multiple stages in epimorphic regeneration. Classically, fin regeneration was characterized by three distinct stages: wound healing, blastema formation, and fin outgrowth. After amputating part of the fin, the surrounding epithelium proliferates and migrates over the wound. At 33 &deg;C, this process occurs within six hours post-amputation (hpa, Figure 1B)6,7. Next, underlying cells from different lineages (ex. bone, blood, glia, fibroblast) re-enter the cell cycle to form a proliferative blastema, while the overlying epidermis continues to proliferate (Figure 1D)8. Outgrowth occurs as cells proximal to the blastema re-differentiate into their respective lineages to form new tissue (Figure 1E)8. Depending on the level of the amputation, full regeneration is completed in a week to a month.
The expression of a large number of gene families, including wnt, hox, fgf, msx, retinoic acid, shh, notch, bmp, and activin-betaA genes, is up-regulated during specific stages of fin regeneration9-16. However, the roles of these genes and their encoded proteins during regeneration have been difficult to assess, unless a specific inhibitor for the protein exists13, a temperature-sensitive mutant exists or a transgenic animal (either overexpressing the wild-type protein or a dominant-negative protein) was generated7,12. We developed a reverse genetic technique to quickly and easily test the function of any gene during fin regeneration.
Morpholino oligonucleotides are widely used to study loss of specific proteins during zebrafish, Xenopus, chick, and mouse development17-19. Morpholinos basepair with a complementary RNA sequence to either block pre-mRNA splicing or mRNA translation. We describe a method to efficiently introduce fluorescein-tagged antisense morpholinos into regenerating zebrafish fins to knockdown expression of the target protein. The morpholino is micro-injected into each blastema of the regenerating zebrafish tail fin and electroporated into the surrounding cells. Fluorescein provides the charge to electroporate the morpholino and to visualize the morpholino in the fin tissue.
This protocol permits conditional protein knockdown to examine the role of specific proteins during regenerative fin outgrowth. In the Discussion, we describe how this approach can be adapted to study the role of specific proteins during wound healing or blastema formation, as well as a potential marker of cell migration during blastema formation.

In vivo Electroporation of Morpholinos into the Regenerating Adult Zebrafish Tail Fin

We describe a method to conditionally knockdown the expression of a target protein during adult zebrafish fin regeneration. This technique involves micro-injecting and electroporating antisense oligonucleotide morpholinos into fin tissue, which allows testing the protein&#x2019;s role in various stages of fin regeneration, including wound healing, blastema formation, and regenerative outgrowth.

En électroporation in vivo de morpholinos dans la régénération des adultes Zebrafish Tail Fin

Certain species of urodeles and teleost fish can regenerate their tissues. Zebrafish have become a widely used model to study the spontaneous regeneration ...

Gavaging Adult Zebrafish

The zebrafish has become an important in vivo model in biomedical research. Effective methods must be developed and utilized to deliver compounds or agents in solutions for scientific research. Current methods for administering compounds orally to adult zebrafish are inaccurate due to variability in voluntary consumption by the fish. A gavage procedure was developed to deliver precise quantities of infectious agents to zebrafish for study in biomedical research. Adult zebrafish over 6 months of age were anesthetized with 150 mg/L of buffered MS-222 and gavaged with 5 &mu;l of solution using flexible catheter implantation tubing attached to a cut 22-G needle tip. The flexible tubing was lowered into the oral cavity of the zebrafish until the tip of the tubing extended past the gills (approximately 1 cm). The solution was then injected slowly into the intestinal tract. This method was effective 88% of the time, with fish recovering uneventfully. This procedure is also efficient as one person can gavage 20-30 fish in one hour. This method can be used to precisely administer agents for infectious diseases studies, or studies of other compounds in adult zebrafish.

The increasing use of zebrafish as an animal model requires the development of effective methods for the delivery of known quantities of compounds and solutions. The gavage procedure described below allows for the oral delivery of precise volumes of solution reliably, safely and efficiently to adult zebrafish.

Gavage poisson zèbre pour adultes

The zebrafish has become an important in vivo model in biomedical research. Effective methods must be developed and utilized to deliver compounds or ...

An Assay for Lateral Line Regeneration in Adult Zebrafish

Due to the clinical importance of hearing and balance disorders in man, model organisms such as the zebrafish have been used to study lateral line development and regeneration. The zebrafish is particularly attractive for such studies because of its rapid development time and its high regenerative capacity. To date, zebrafish studies of lateral line regeneration have mainly utilized fish of the embryonic and larval stages because of the lower number of neuromasts at these stages. This has made quantitative analysis of lateral line regeneration/and or development easier in the earlier developmental stages. Because many zebrafish models of neurological and non-neurological diseases are studied in the adult fish and not in the embryo/larvae, we focused on developing a quantitative lateral line regenerative assay in adult zebrafish so that an assay was available that could be applied to current adult zebrafish disease models. Building on previous studies by Van Trump et al.17&#160;that described procedures for ablation of hair cells in adult Mexican blind cave fish and zebrafish (Danio rerio), our assay was designed to allow quantitative comparison between control and experimental groups. This was accomplished by developing a regenerative neuromast standard curve based on the percent of neuromast reappearance over a 24 hr time period following gentamicin-induced necrosis of hair cells in a defined region of the lateral line. The assay was also designed to allow extension of the analysis to the individual hair cell level when a higher level of resolution is required.

Because many zebrafish models of neurological and non-neurological diseases are studied in the adult fish rather than the embryo/larvae, we developed a quantitative lateral line regenerative assay that can be applied to adult zebrafish disease models. The assay involved resolution at the 1) neuromast and 2) individual hair cell levels.

Un test pour ligne latérale de régénération à l&#39;âge adulte de poisson zèbre

Due to the clinical importance of hearing and balance disorders in man, model organisms such as the zebrafish have been used to study lateral line ...

Gap Junctional Intercellular Communication: A Functional Biomarker to Assess Adverse Effects of Toxicants and Toxins, and Health Benefits of Natural Products

This protocol describes a scalpel loading-fluorescent dye transfer (SL-DT) technique that measures intercellular communication through gap junction channels, which is a major intercellular process by which tissue homeostasis is maintained. Interruption of gap junctional intercellular communication (GJIC) by toxicants, toxins, drugs, etc. has been linked to numerous adverse health effects. Many genetic-based human diseases have been linked to mutations in gap junction genes. The SL-DT technique is a simple functional assay for the simultaneous assessment of GJIC in a large population of cells. The assay involves pre-loading cells with a fluorescent dye by briefly perturbing the cell membrane with a scalpel blade through a population of cells. The fluorescent dye is then allowed to traverse through gap junction channels to neighboring cells for a designated time. The assay is then terminated by the addition of formalin to the cells. The spread of the fluorescent dye through a population of cells is assessed with an epifluorescence microscope and the images are analyzed with any number of morphometric software packages that are available, including free software packages found on the public domain. This assay has also been adapted for in vivo studies using tissue slices from various organs from treated animals. Overall, the SL-DT assay can serve a broad range of in vitro pharmacological and toxicological needs, and can be potentially adapted for high throughput set-up systems with automated fluorescence microscopy imaging and analysis to elucidate more samples in a shorter time.

This protocol describes a scalpel loading-fluorescent dye transfer technique that measures intercellular communication through gap junction channels. Gap junctional intercellular communication is a major cellular process by which tissue homeostasis is maintained and disruption of this cell signaling has adverse health effects.

Gap Junctional intercellulaire Communication: Un biomarqueur fonctionnelle pour évaluer les effets néfastes des substances toxiques et les toxines, et bienfaits pour la santé des produits naturels

This protocol describes a scalpel loading-fluorescent dye transfer (SL-DT) technique that measures intercellular communication through gap junction ...

Immunolabelling Myofiber Degeneration in Muscle Biopsies

The necrosis of muscle fibres (myonecrosis) plays a central role in the pathogenesis of several muscle conditions, including muscular dystrophies. Therapeutic options addressing the causes of muscular dystrophy pathogenesis are expected to alleviate muscle degeneration. Therefore, a method to assay and quantify the extent of cell death in muscle biopsies is needed. Conventional methods to observe myofiber degeneration in situ are either poorly quantitative or rely on the injection of vital dyes. In this article, an immunofluorescence protocol is described that stains necrotic myofibers by targeting immunoglobulin G (IgG) uptake by myofibers. The IgG uptake method is based on cell features characterizing the necrotic demise, including 1) the loss of plasma membrane integrity with the release of damage-associated molecular patterns and 2) the uptake of plasmatic proteins. In murine cross-sections, the co-immunolabelling of myofibers, extracellular matrix proteins, and mouse IgG allows clean and straightforward identification of myofibers with necrotic fate. This simple method is suitable for quantitative analysis and applicable to all species, including human samples, and does not require the injection of vital dye. The staining of necrotic myofibers by IgG uptake can also be paired with other co-immunolabelling.

Described here is a protocol for direct immunolabelling of necrotic myofibers in muscle cryosections. Necrotic cells are permeable to serum proteins, including immunoglobulin G (IgG). Revealing the uptake of IgG by myofibers allows the identification and quantification of myofibers that undergo necrosis regardless of muscle condition.

Immunolabelling Myofiber Dégénérescence dans les biopsies musculaires

The necrosis of muscle fibres (myonecrosis) plays a central role in the pathogenesis of several muscle conditions, including muscular dystrophies. ...

Nitroreductase/Metronidazole-Mediated Ablation and a MATLAB Platform (RpEGEN) for Studying Regeneration of the Zebrafish Retinal Pigment Epithelium

The retinal pigment epithelium (RPE) resides at the back of the eye and performs functions essential for maintaining the health and integrity of adjacent retinal and vascular tissues. At present, the limited reparative capacity of mammalian RPE, which is restricted to small injuries, has hindered progress to understanding in vivo RPE regenerative processes. Here, a detailed methodology is provided to facilitate the study of in vivo RPE repair utilizing the zebrafish, a&#160;vertebrate model capable of robust tissue regeneration. This protocol describes a transgenic nitroreductase/metronidazole (NTR/MTZ)-mediated injury paradigm (rpe65a:nfsB-eGFP), which results in ablation of the central two-thirds of the RPE after 24 h treatment with MTZ, with subsequent tissue recovery. Focus is placed on RPE ablations in larval zebrafish and methods for testing the effects of pharmacological compounds on RPE regeneration are also outlined. Generation and validation of RpEGEN, a MATLAB script created to automate quantification of RPE regeneration based on pigmentation, is also discussed. Beyond active RPE repair mechanisms, this protocol can be expanded to studies of RPE degeneration and injury responses as well as the effects of RPE damage on adjacent retinal and vascular tissues, among other cellular and molecular processes. This zebrafish system holds significant promise in identifying genes, networks, and processes that drive RPE regeneration and RPE disease-related mechanisms, with the long-term goal of applying this knowledge to mammalian systems and, ultimately, toward therapeutic development.

Nitroreductase/Metronidazole-Mediated Ablation and a MATLAB Platform RpEGEN for Studying Regeneration of the Zebrafish Retinal Pigment Epithelium

This protocol describes the methodology to genetically ablate the retinal pigment epithelium (RPE) using a transgenic zebrafish model. Adapting the protocol to incorporate signaling pathway modulation using pharmacological compounds is extensively detailed. A MATLAB platform for quantifying RPE regeneration based on pigmentation was developed and is presented and discussed.

Ablation médiée par la nitroréductase/métronidazole et une plate-forme MATLAB (RpEGEN) pour l’étude de la régénération de l’épithélium pigmentaire rétinien du poisson-zèbre

The retinal pigment epithelium (RPE) resides at the back of the eye and performs functions essential for maintaining the health and integrity of adjacent ...

Efficient and Consistent Generation of Retinal Pigment Epithelium/Choroid Flatmounts from Human Eyes for Histological Analysis

The retinal pigment epithelium (RPE) and retina are functionally and structurally connected tissues that work together to regulate light perception and vision. Proteins on the RPE apical surface are tightly associated with proteins on the photoreceptor outer segment surface, making it difficult to consistently separate the RPE from the photoreceptors/retina. We developed a method to efficiently separate the retina from the RPE of human eyes to generate complete RPE/choroid and retina flatmounts for separate cellular analysis of the photoreceptors and RPE cells. An intravitreal injection of a high-osmolarity solution of D-mannitol, a sugar not transported by the RPE, induced the separation of the RPE and retina across the entire posterior chamber without causing damage to the RPE cell junctions. No RPE patches were observed attached to the retina. Phalloidin labeling of actin showed RPE shape preservation and allowed morphometric analysis of the entire epithelium. An artificial intelligence (AI)-based software was developed to accurately recognize and segment the RPE cell borders and quantify 30 different shape metrics. This dissection method is highly reproducible and can be easily extended to other animal models.

We describe a method to efficiently separate retinal pigment epithelium (RPE) from the retina in human eyes and generate whole RPE/choroid flatmounts for histological and morphometric analyses of the RPE.

Génération efficace et cohérente d’épithélium/platures choroïdes pigmentaires rétiniens à partir d’yeux humains pour l’analyse histologique

The retinal pigment epithelium (RPE) and retina are functionally and structurally connected tissues that work together to regulate light perception and ...