scholarly journals Spatially unique Shh-Fgf8 distribution in regenerating limb guarantees consistent limb morphogenesis in different limb sizes and contributes to axolotl specific digit patterning.

2022 ◽  
Author(s):  
saya furukawa ◽  
sakiya yamamoto ◽  
rena kashimoto ◽  
yoshihiro morishita ◽  
Akira Satoh
Keyword(s):  
Limb Regeneration ◽  
Ambystoma Mexicanum ◽  
Dependent Manner ◽  
Expression Domain ◽  
Developmental Processes ◽  
Limb Morphogenesis ◽  
Cartilage Differentiation ◽  
Anterior Side ◽  
Two Factors ◽  
Morphological Defects

Limb regeneration in Ambystoma mexicanum occurs in various sizes of fields and can recreate consistent limb morphology. It was not known what mechanism supports such stable limb morphogenesis regardless of size. Limb regeneration in urodele amphibians has been basically considered to recapitulate the limb developmental processes. Many molecules in the limb developmental processes are conserved with other tetrapods. SHH and FGF8 play important roles in the morphogenesis of limbs among them. Focusing on these two factors, we investigated the detailed expression pattern of Shh and Fgf8 in the various sizes of blastema in axolotl limb regeneration. Fgf8 is expressed in the anterior side of a blastema and Shh is expressed in the posterior side. These are maintained in a mutually dependent manner. We also clarified that the size of Shh and Fgf8 expression domains were scaled as the size of the blastemas increased. However, it was found that the secretion and working range of SHH were kept constant. We also found that the consistent SHH secretion range contributed to promoting cell proliferation and the first digital cartilage differentiation near the Shh expression domain. This would be a reasonable system to guarantees constant limb morphogenesis regardless of the blastema size. We also showed that the Shh-Fgf8 expression domain was shifted posteriorly as the digital differentiation progressed. Consistently, slowing the timing of blocking Shh signaling resulted in morphological defects that could be observed in only posterior digits. The revealed posteriorly shifting Shh-Fgf8 domain might explain urodele specific digit formation, in which digits are added posteriorly.

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.

The influence of aminopterin on limb regeneration in Ambystoma mexicanum

Development ◽  
1966 ◽  
Vol 16 (1) ◽  
pp. 143-158
Author(s):  
D. O. E. Gebhardt ◽  
J. Faber
Keyword(s):  
Toluidine Blue ◽  
Growth Retardation ◽  
Limb Regeneration ◽  
Ambystoma Mexicanum ◽  
Ontogenetic Development ◽  
Antimitotic Agent ◽  
Chemical Substances ◽  
Histamine Formation ◽  
Number Of Authors

During the last twenty-five years a number of authors have studied the influence of chemical substances on limb regeneration in amphibians. Examples of compounds which have been tested so far are: (1) the antimitotic agent, colchicine (Thornton, 1943); (2) the salt, beryllium nitrate (Thornton, 1949, 1950, 1951); (3) the carcinogens, dibenzanthracene and methylcholanthrene (Karczmar & Berg, 1952; Ruben & Balls, 1964); (4) the lathyrus factor, β- aminopropionitrile (Chang, Witschi & Ponseti, 1955); (5) the hormone, thyroxine (Hay, 1956); (6) atropine and other neuropharmacological drugs (Singer, Davis & Scheuing, 1960); (7) the metachromatic dye, toluidine blue (Csaba, Bierbauer & Törö, 1961); and (8) semicarbazide, an inhibitor of histamine formation (Deck & Shapiro, 1963). Most of these substances caused growth retardation as well as malformations of the limb regenerates. A number of other investigators have studied the effects of chemicals on the ontogenetic development of the amphibian limb.

Morphogenetic properties of the skin axolotl limb regeneration

Development ◽  
1980 ◽  
Vol 58 (1) ◽  
pp. 265-288
Author(s):  
Jonathan M. W. Slack
Keyword(s):  
Limb Regeneration ◽  
Host Tissue ◽  
Tissue Formation ◽  
Cellular Composition ◽  
Posterior Half ◽  
Tail Bud ◽  
Threshold Theory ◽  
Anterior Side ◽  
Immunological Rejection ◽  
Host Tissues

A study has been made of the morphogenetic properties of anterior and posterior skin from the lower forelimb of the axolotl. The basic experiment consisted of a graft of a half cuff of skin from a donor to a host limb followed by a 2-week healing period, amputation through the graft, and a study of the resulting regenerate. Limbs with double posterior skin formed double posterior regenerates and, in contrast, limbs with double anterior skin formed normal or slightly hypomorphic regenerates. Posterior skin from post-metamorphic animals had a similar but weaker effect to that from ordinary axolotls. Immunological rejection of allografts could be completely avoided if the donor limb was transplanted to the flank of the host when both were at the stage of tail-bud embryos, and the skin graft was later carried out between the supernumerary limb and one of the host limbs. This technique was used to show that immunological rejection does not affect the formation of duplicates from the limbs with double posterior skin, and to facilitate the studies of the cellular provenance of the regenerate. The cellular composition of duplicate regenerates was studied by using both triploid donors and triploid hosts. It was shown that the posterior side of the duplications consisted wholly of host tissue and the anterior side consisted of mixed donor and host tissue. Formation of the duplicated regenerate therefore seems to involve positional reprogramming of both donor and host tissues together with metaplasia of the donor tissue. It was not possible to inhibit the duplication-inducing property of posterior skin by treatment with a variety of enzymes. A model based on the serial threshold theory of regeneration is advanced to explain the results.This model successfully accounts for the observed non-equivalence of anterior and posterior skin, and also explains the different regeneration behaviour of anterior and posterior half limbs, the limited regeneration of double anterior limbs, and the pattern expansion and contraction shown by regenerates from double posterior limbs.

scholarly journals Conservation analysis of core cell cycle regulators and their transcriptional behavior during limb regeneration in Ambystoma mexicanum

2020 ◽  
Vol 164 ◽  
pp. 103651
Author(s):  
Annie Espinal-Centeno ◽  
Melissa Dipp-Álvarez ◽  
Carlos Saldaña ◽  
Laszlo Bako ◽  
Alfredo Cruz-Ramírez
Keyword(s):  
Cell Cycle ◽  
Limb Regeneration ◽  
Ambystoma Mexicanum ◽  
Cell Cycle Regulators ◽  
Conservation Analysis

scholarly journals Repeated modification of early limb morphogenesis programmes underlies the convergence of relative limb length in Anolis lizards

2011 ◽  
Vol 279 (1729) ◽  
pp. 739-748 ◽  
Author(s):  
Thomas J. Sanger ◽  
Liam J. Revell ◽  
Jeremy J. Gibson-Brown ◽  
Jonathan B. Losos
Keyword(s):  
Natural Selection ◽  
Developmental Trajectories ◽  
Limb Length ◽  
Long Bone ◽  
Length Variation ◽  
Developmental Processes ◽  
Independent Evolution ◽  
Limb Morphogenesis ◽  
Habitat Specialists ◽  
Phenotypic Convergence

The independent evolution of similar morphologies has long been a subject of considerable interest to biologists. Does phenotypic convergence reflect the primacy of natural selection, or does development set the course of evolution by channelling variation in certain directions? Here, we examine the ontogenetic origins of relative limb length variation among Anolis lizard habitat specialists to address whether convergent phenotypes have arisen through convergent developmental trajectories. Despite the numerous developmental processes that could potentially contribute to variation in adult limb length, our analyses reveal that, in Anolis lizards, such variation is repeatedly the result of changes occurring very early in development, prior to formation of the cartilaginous long bone anlagen.

scholarly journals The PIN-FORMED Auxin Efflux Carriers in Plants

2018 ◽  
Vol 19 (9) ◽  
pp. 2759 ◽  
Author(s):  
Jing-Jing Zhou ◽  
Jie Luo
Keyword(s):  
Subcellular Location ◽  
Structure Evolution ◽  
Dependent Manner ◽  
Subcellular Trafficking ◽  
Developmental Processes ◽  
Auxin Distribution ◽  
Development Processes ◽  
Auxin Efflux Carriers ◽  
Hydrophilic Loop ◽  
Polar Distribution

Auxin plays crucial roles in multiple developmental processes, such as embryogenesis, organogenesis, cell determination and division, as well as tropic responses. These processes are finely coordinated by the auxin, which requires the polar distribution of auxin within tissues and cells. The intercellular directionality of auxin flow is closely related to the asymmetric subcellular location of PIN-FORMED (PIN) auxin efflux transporters. All PIN proteins have a conserved structure with a central hydrophilic loop domain, which harbors several phosphosites targeted by a set of protein kinases. The activities of PIN proteins are finely regulated by diverse endogenous and exogenous stimuli at multiple layers—including transcriptional and epigenetic levels, post-transcriptional modifications, subcellular trafficking, as well as PINs’ recycling and turnover—to facilitate the developmental processes in an auxin gradient-dependent manner. Here, the recent advances in the structure, evolution, regulation and functions of PIN proteins in plants will be discussed. The information provided by this review will shed new light on the asymmetric auxin-distribution-dependent development processes mediated by PIN transporters in plants.

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