Citral, an inhibitor of retinoic acid synthesis, modifies pattern formation during limb regeneration in the axolotl Ambystoma mexicanum

1999 ◽  
Vol 77 (11) ◽  
pp. 1835-1837 ◽  
Author(s):  
Steven R Scadding
Keyword(s):  
Retinoic Acid ◽  
Pattern Formation ◽  
Limb Regeneration ◽  
Acid Synthesis ◽  
Ambystoma Mexicanum

While the effects of exogenous retinoids on amphibian limb regeneration have been studied extensively, the role of endogenous retinoids is not clear. Hence, I wished to investigate the role of endogenous retinoic acid during axolotl limb regeneration. Citral is a known inhibitor of retinoic acid synthesis. Thus, I treated regenerating limbs of the larval axolotl Ambystoma mexicanum with citral. The result of this inhibition of retinoic acid synthesis was that limb regeneration became extremely irregular and hypomorphic, with serious pattern defects, or was inhibited altogether. I conclude that endogenous retinoic acid plays an important role in pattern formation during limb regeneration.

Symmetrical vascularization patterns in normal and retinoic acid treated limb regenerates of the axolotl, Ambystoma mexicanum

1998 ◽  
Vol 76 (9) ◽  
pp. 1795-1796 ◽  
Author(s):  
Steven R Scadding ◽  
Andrew Burns
Keyword(s):  
Retinoic Acid ◽  
Pattern Formation ◽  
Vascular System ◽  
Limb Regeneration ◽  
Ambystoma Mexicanum ◽  
Limb Pattern ◽  
Regeneration Blastema

The purpose of this investigation was to determine whether there were any asymmetries in the vascularization of the limb-regeneration blastema in the axolotl, Ambystoma mexicanum, that might be related to pattern formation, and to determine if retinoic acid could modify the vascular patterns of the blastema. We used acrylic casts of the vascular system of the limbs to assess the pattern of vascularization. We observed a very regular symmetrical arrangement of capillaries in the limb-regeneration blastema that did not appear to be modified by doses of retinoic acid sufficient to modify the limb pattern.

Gap junctions in the limb regeneration blastema of the axolotl, Ambystoma mexicanum, are not distributed uniformly and are regulated by retinoic acid

1999 ◽  
Vol 77 (6) ◽  
pp. 902-909
Author(s):  
Leigh-Anne D Miller ◽  
Melissa L Farquhar ◽  
John S Greenwood ◽  
Steven R Scadding
Keyword(s):  
Retinoic Acid ◽  
Gap Junctions ◽  
Limb Regeneration ◽  
Ambystoma Mexicanum ◽  
Limb Bud ◽  
Gap Junctional Communication ◽  
Junctional Communication ◽  
Gap Junctional ◽  
Regeneration Blastema

Gap junctions are thought to play a role in pattern formation during limb development and regeneration by controlling the movement of small regulatory molecules between cells. An anteroposterior gradient of gap junctional communication that is higher posteriorly has been reported in the developing chick limb bud. In both the developing chick limb bud and the amphibian regenerating limb, an anteroposterior retinoic acid gradient is present, and this is also higher posteriorly. On the basis of these observations, we decided to examine the role of gap junctional communication in the regenerating amphibian limb. Gap junctions were observed in both the axolotl, Ambystoma mexicanum, limb regeneration blastema and cardiac tissue (as a positive control), using immunohistochemical labelling and laser scanning confocal microscopy. The scrape-loading/dye transfer technique for tracing the movement of a gap junction permeable dye, Lucifer yellow, showed that in blastemal epidermis there were nonuniform distributions of gap junctions in both the dorsoventral and anteroposterior axes of the blastema. Retinoic acid was found to increase gap junctional permeability in blastemal epidermis 48 h after injection and in blastemal mesenchyme 76 h after injection. The potential role of gap junctions during pattern formation in limb regeneration is discussed based on these results.

Retinoic acid signaling is required during early chick limb development

Development ◽  
1996 ◽  
Vol 122 (5) ◽  
pp. 1385-1394 ◽  
Author(s):  
J.A. Helms ◽  
C.H. Kim ◽  
G. Eichele ◽  
C. Thaller
Keyword(s):  
Retinoic Acid ◽  
Limb Development ◽  
Acid Synthesis ◽  
Apical Ectodermal Ridge ◽  
Limb Bud ◽  
Retinoid Receptor ◽  
Limb Morphogenesis ◽  
Wing Bud ◽  
Zone Of Polarizing Activity

In the chick limb bud, the zone of polarizing activity controls limb patterning along the anteroposterior and proximodistal axes. Since retinoic acid can induce ectopic polarizing activity, we examined whether this molecule plays a role in the establishment of the endogenous zone of polarizing activity. Grafts of wing bud mesenchyme treated with physiologic doses of retinoic acid had weak polarizing activity but inclusion of a retinoic acid-exposed apical ectodermal ridge or of prospective wing bud ectoderm evoked strong polarizing activity. Likewise, polarizing activity of prospective wing mesenchyme was markedly enhanced by co-grafting either a retinoic acid-exposed apical ectodermal ridge or ectoderm from the wing region. This equivalence of ectoderm-mesenchyme interactions required for the establishment of polarizing activity in retinoic acid-treated wing buds and in prospective wing tissue, suggests a role of retinoic acid in the establishment of the zone of polarizing activity. We found that prospective wing bud tissue is a high-point of retinoic acid synthesis. Furthermore, retinoid receptor-specific antagonists blocked limb morphogenesis and down-regulated a polarizing signal, sonic hedgehog. Limb agenesis was reversed when antagonist-exposed wing buds were treated with retinoic acid. Our results demonstrate a role of retinoic acid in the establishment of the endogenous zone of polarizing activity.

Retinoic acid stimulates the synthesis of a novel heat shock protein in the regenerating forelimb of the newt

1993 ◽  
Vol 71 (1-2) ◽  
pp. 43-50 ◽  
Author(s):  
Robert L. Carlone ◽  
Robert P. Boulianne ◽  
K. Marion Vijh ◽  
Heather Karn ◽  
Gordon A. D. Fraser
Keyword(s):  
Retinoic Acid ◽  
Heat Shock ◽  
Stress Proteins ◽  
Limb Regeneration ◽  
Stress Protein ◽  
Cross Reactivity ◽  
Hsp 70 ◽  
Peptide Map ◽  
Shock Proteins

Morphogenetic effects of retinoic acid (RA) on the urodele amphibian limb regenerate pattern have been well documented, but little is known regarding the mechanism of this action of RA at the molecular level. Since exogenous RA, at concentrations sufficient to cause proximalization, represents a significant stress to newts and has been shown previously to elicit increased synthesis of heat shock proteins (HSPs) in mouse embryo limb buds, we investigated the effects of this putative morphogen on the synthesis of members of the 70-kilodalton (70-kDa) stress protein family in amputated forelimbs of the newt Notophthalmus viridescens. Injection (i.p.) of RA in dimethyl sulfoxide (DMSO), at a dose sufficient to cause significant proximal–distal reduplication of the pattern in 50% of animals treated, resulted in increased synthesis and accumulation of a 73-kDa protein with a pi of approximately 6.75. The synthesis of this same protein is increased in limb tissues as a result of a brief 35 °C heat shock. This protein is electrophoretically distinct from the newt HSP 70 family members, displays a different partial peptide map, and shows no immunological cross-reactivity with an anti-human HSP 70 monoclonal antibody. It may be a member of a separate family of 70- to 73-kDa HSPs. Interestingly, the synthesis of this protein is increased and it is more abundant in control, proximal moderate-early bud stage regenerates at 6 days after i.p. injection of DMSO than in similarly treated distal regenerates. This protein is, in addition, increased in distal regenerates to proximal levels by a prior injection of RA. The significance of these findings with regard to the possible role of stress proteins in the morphogenetic processes underlying limb regeneration is discussed.Key words: heat shock, limb regeneration, retinoic acid, pattern formation, newt.

Effects of concanavalin A on limb regeneration in the axolotl Ambystoma mexicanum

1997 ◽  
Vol 75 (10) ◽  
pp. 1728-1732
Author(s):  
Steven R. Scadding
Keyword(s):  
Pattern Formation ◽  
Concanavalin A ◽  
Limb Regeneration ◽  
Ambystoma Mexicanum ◽  
Teratogenic Effect ◽  
Low Doses ◽  
Con A ◽  
Higher Doses

The purpose of this investigation was to determine the effects, if any, of concanavalin A (Con A) on the process of pattern formation during limb regeneration in the axolotl Ambystoma mexicanum. Con A was administered to regenerating axolotl forelimbs in a Hydron disk that released the Con A slowly over a period of time. The results indicate that Con A is teratogenic to the regenerating axolotl limb, causing reductions in the number, size, and quality of skeletal elements present, with increasing reductions and malformations as the dose is increased. Low doses resulted in a reduction in the number of carpals or phalanges. Higher doses resulted in more drastic malformations, including the absence of digits. The implications of this teratogenic effect of Con A on limb regeneration are discussed in the context of the possible mechanisms of pattern formation.

The role of irradiated tissue during pattern formation in the regenerating limb

Development ◽  
1979 ◽  
Vol 50 (1) ◽  
pp. 235-242
Author(s):  
M. Maden
Keyword(s):  
Pattern Formation ◽  
Limb Regeneration ◽  
Recent Model ◽  
Vertebrate Development ◽  
Regeneration Blastema

The amphibian limb regeneration blastema is used here to examine whether irradiated, non-dividing tissue can participate in the development of new patterns of morphogenesis. Irradiated blastemas were rotated 180° on normal stumps and normal blastemas rotated on irradiated stumps. In both cases supernumerary elements developed from the unirradiated tissue. The supernumeraries were defective but this did not seem to be due to a lack of tissue. Rather it suggested that this could be a realization of compartments in vertebrate development or simply reflect the limited regulative ability of the blastema. The results are also discussed in relation to a recent model of pattern formation.

scholarly journals Efficient gene knockin in axolotl and its use to test the role of satellite cells in limb regeneration

2017 ◽  
Vol 114 (47) ◽  
pp. 12501-12506 ◽  
Author(s):  
Ji-Feng Fei ◽  
Maritta Schuez ◽  
Dunja Knapp ◽  
Yuka Taniguchi ◽  
David N. Drechsel ◽  
...  
Keyword(s):  
Reporter Gene ◽  
Satellite Cells ◽  
Limb Regeneration ◽  
Independent Method ◽  
Ambystoma Mexicanum ◽  
Cell Populations ◽  
Genetic Tool ◽  
Efficient Gene ◽  
Unique Model

Salamanders exhibit extensive regenerative capacities and serve as a unique model in regeneration research. However, due to the lack of targeted gene knockin approaches, it has been difficult to label and manipulate some of the cell populations that are crucial for understanding the mechanisms underlying regeneration. Here we have established highly efficient gene knockin approaches in the axolotl (Ambystoma mexicanum) based on the CRISPR/Cas9 technology. Using a homology-independent method, we successfully inserted both the Cherry reporter gene and a larger membrane-tagged Cherry-ERT2-Cre-ERT2 (∼5-kb) cassette into axolotl Sox2 and Pax7 genomic loci. Depending on the size of the DNA fragments for integration, 5–15% of the F0 transgenic axolotl are positive for the transgene. Using these techniques, we have labeled and traced the PAX7-positive satellite cells as a major source contributing to myogenesis during axolotl limb regeneration. Our work brings a key genetic tool to molecular and cellular studies of axolotl regeneration.

Sign in / Sign up

Export Citation Format

Share Document