• This type of regeneration is rare among vertebrates but does occur in the African clawed frog Xenopus laevis , traditionally a model organism for the study of early development. (biomedcentral.com)
  • Xenopus tadpoles can regenerate their tails, limb buds and the lens of the eye, although the ability of the latter two organs to regenerate diminishes with advancing developmental stage. (biomedcentral.com)
  • Activation of this transgene blocks regeneration of the tail and limb of Xenopus tadpoles. (biomedcentral.com)
  • Gene Ontology analysis showed that genes involved in embryonic development and growth are significantly over-represented in regenerating early hindlimb buds and that successful regeneration in the Xenopus hindlimb correlates with the induction of stress response pathways. (biomedcentral.com)
  • Gene over-expression analyses in Xenopus limb and tail regeneration have indicated that successful regeneration requires the re-activation of developmental FGF or BMP signalling pathways [ 8 - 12 ]. (biomedcentral.com)
  • We have developed a heat shock inducible transgenic line ( N1 ) of Xenopus in which the BMP antagonist Noggin can be induced at a specific time during either development or regeneration, repressing BMP signalling [ 10 , 12 ]. (biomedcentral.com)
  • Here we review recent insights into the biophysical, biochemical, and epigenetic processes that underlie regenerative healing in amphibians, focusing particularly on tail and limb regeneration in Xenopus . (frontiersin.org)
  • We examined the bioelectric properties (resting potential gradients in the epidermis) of Xenopus laevis froglets undergoing hindlimb amputation and observed that the contralateral (undamaged) limb exhibits apparent depolarization signals immediately after the opposite hindlimb is amputated. (biologists.com)
  • Just as plant cells respond to injury by undergoing callus formation via dedifferentiation, some animal models dedifferentiate their cells to form blastema, which are analogous to plant calluses, after limb amputation. (wikipedia.org)
  • The wound epithelium of N1 transgenic hindlimb buds, which forms over the cut surface of the limb bud after amputation, does not transition normally into the distal thickened apical epithelial cap. (biomedcentral.com)
  • N1 transgenic hindlimbs, which do not regenerate, do not form an apical epithelial cap or cone shaped blastema following amputation. (biomedcentral.com)
  • Amputation-induced proliferation occurred predominantly within the epidermal and intestinal epithelium, as well as wound-adjacent muscle fibers, where clusters of cells at the same stage of the cell cycle were found. (mdpi.com)
  • In mammals, a limb amputation or spinal cord transection is followed by inflammation and fibrotic scarring that leaves the animal with a permanent disability. (frontiersin.org)
  • We have used this line to show that BMP function is not only required for appendage regeneration but that it is specifically needed to generate a proliferating blastema while being dispensable for wound healing [ 12 ]. (biomedcentral.com)
  • Appendage regeneration, particularly of the tadpole tail, has been widely studied before, during and after this period. (frontiersin.org)
  • Lowered Notch1 expression resulted in no tadpole tail regeneration, and induced Notch1 expression was able to partially rescue tail regeneration in the form of notochord and spinal cord (but very little musculature. (wikipedia.org)
  • Injuries that sever tissues such as the limb or spinal cord are met with radically different outcomes among vertebrates. (frontiersin.org)
  • In the current study, we have taken advantage of the N1 transgenic line to directly compare morphology and gene expression in same stage regenerating vs. BMP signalling deficient non-regenerating hindlimb buds. (biomedcentral.com)
  • Comparison of gene expression in stage matched N1 vs. wild type hindlimb buds has revealed several new targets for regeneration research. (biomedcentral.com)
  • While all vertebrates are capable of some types of tissue regeneration, most, including humans, have lost the ability to regenerate whole structures such as limbs ( epimorphic regeneration ), [ 1 ]. (biomedcentral.com)
  • In urodele amphibians such as axolotls and newts, the same injury is followed by scarless regenerative healing that can fully restore both the lost tissue and its function (reviewed in Tanaka, 2016 ). (frontiersin.org)
  • The pathways discussed below are found to be closely related to dedifferentiation and regeneration in some species. (wikipedia.org)
  • Because not one pathway has been elucidated as necessary for all dedifferentiation and regeneration, it is possible that the mechanism functions differently in different species. (wikipedia.org)
  • Once the wound is healed, the cells of the stump must mobilise under the wound epidermis and begin the process of replacing lost tissues, by forming a proliferating blastema. (biomedcentral.com)
  • The pattern of depolarization matches that of the amputated limb and is correlated to the position and type of injury, revealing that information about damage is available to remote body tissues and is detectable non-invasively in vivo by monitoring the bioelectric state. (biologists.com)
  • It is well-established that early embryonic signaling pathways are critical for growth and patterning of new tissue during regeneration. (frontiersin.org)
  • Once BMP expression was restored, Msx1 expression was also restored, and regeneration proceeded.19 Similar studies have shown similar results in mouse digit tip regeneration. (wikipedia.org)
  • In recent years, interest in the possible molecular regulators of cell proliferation and differentiation in a wide range of regeneration models has grown significantly, but the cell kinetics of this process remain largely a mystery. (mdpi.com)
  • For example, MMP, the matrix metalloproteinase, has shown up-regulated activity during early stages of limb regeneration. (wikipedia.org)
  • Regeneration of damaged body parts requires coordination of size, shape, location and orientation of tissue with the rest of the body. (biologists.com)
  • Here we try to elucidate the cellular aspects of regeneration by EdU incorporation in intact and posteriorly amputated annelid Alitta virens using quantitative analysis. (mdpi.com)
  • Cells keep a memory of their tissue origin during axolotl limb regeneration. (nature.com)
  • Our results suggest that the role of nerves is conserved and that Fgf+Bmp signals play key roles in axolotl organ-level regeneration. (nature.com)
  • The axolotl is one of the few tetrapods that are capable of regenerating complicated biological structures, such as complete limbs, throughout adulthood. (nih.gov)
  • Upon injury the axolotl generates a population of regeneration-competent limb progenitor cells known as the blastema, which will grow, establish pattern, and differentiate into the missing limb structures. (nih.gov)
  • In this study, we focused on the structure of collagen fibers with collagen braiding cells, and cell origin in axolotl skin regeneration. (bvsalud.org)
  • Salamanders capable of limb regeneration form a blastema (a mass of lineage-restricted progenitor cells 4 ) after limb loss, and our findings suggest that ear tissue regeneration in Acomys may proceed through the assembly of a similar structure. (nature.com)
  • Urodele amphibians (eg, salamanders and newts) can regenerate complex tissues that are identical to the original in both appearance and function. (medrego.com)
  • The presence of nerves is an important factor in successful organ regeneration in amphibians. (nature.com)
  • We also discovered that nerves induce the regeneration of collagen fibers. (bvsalud.org)
  • This blastema then reforms into all the components of the missing limb: bone, muscle, nerves, and blood vessels. (medrego.com)
  • Here, we reevaluated tooth regeneration processes in axolotls using a three-dimensional reconstitution method called CoMBI and found that tooth regeneration is nerve-dependent although the dentary bone is independent of nerve presence. (nature.com)
  • Axolotls have been considered to be able to regenerate their skin completely. (bvsalud.org)
  • BACKGROUND: Axolotls can regenerate their limbs. (bvsalud.org)
  • As re-emergent interest in regenerative medicine seeks to isolate molecular pathways controlling tissue regeneration in mammals, Acomys may prove useful in identifying mechanisms to promote regeneration in lieu of fibrosis and scarring. (nature.com)
  • Understanding how these mechanisms impact on regenerative processes is essential to devise therapeutic approaches to improve tissue regeneration and extend healthspan. (mdpi.com)
  • In the wounded dermis, cells involved in skin repair/regeneration were derived from both the surrounding dermis and the subcutaneous tissue. (bvsalud.org)
  • In this review we focus on the crucial early events that occur during wound healing, the neural-epithelial interactions that drive the formation of the early blastema, and how these mechanisms differ from those of other species that have restricted regenerative potential, such as humans. (nih.gov)
  • Our findings contribute to the elucidation of the fundamental mechanisms of true skin regeneration and provide useful insights for pioneering new skin treatments. (bvsalud.org)
  • Transcriptomic profiling of regenerating ventricles in cryoinjured fish subjected to exercise identified genes possibly involved in the cardioprotective effects of exercise and that could represent potential targets for heart regeneration strategies. (frontiersin.org)
  • In their limb regeneration process, developmental genes are re-expressed and reorganize the developmental axes, in which the position-specific genes are properly re-expressed. (bvsalud.org)
  • Notably, we found that regenerative capacity in Acomys was extended to ear holes, where the mice exhibited complete regeneration of hair follicles, sebaceous glands, dermis and cartilage. (nature.com)
  • In addition, it raised the question as to whether the electric organ evolved from muscle by similar or different processes in each lineage. (biologists.com)
  • However, how such position specificity is reorganized in the regeneration processes has not been clarified. (bvsalud.org)
  • Electrocytes arise from the fusion of fully differentiated muscle fibers, mainly those expressing fast isoforms of myosin. (biologists.com)
  • Our recent study updated this theory with the finding that the lattice structure of dermal collagen fibers was not fully regenerated after skin injury. (bvsalud.org)
  • and the possible cardioprotective effects of exercise on heart regeneration in this species have not been investigated to date. (frontiersin.org)
  • This study underscores the importance of investigating regenerative phenomena outside of conventional model organisms, and suggests that mammals may retain a higher capacity for regeneration than was previously believed. (nature.com)
  • It focuses on established models of mammalian regeneration as well as on models in which regenerative abilities do not decline with age, as these can deliver valuable insights for our understanding of the interplay between regeneration and aging. (mdpi.com)
  • We also discuss how the presence of cells from the different axes of the limb is required for the continued growth and establishment of pattern in the blastema as described in the polar coordinate model, and how this positional information is reprogrammed in blastema cells during regeneration. (nih.gov)
  • Multiple cell types from the mature limb stump contribute to the blastema at different stages of regeneration, and we discuss the contribution of these types to the regenerate with reference to whether they are "pattern-forming" or "pattern-following" cells. (nih.gov)
  • In contrast to mammals, adult zebrafish cardiomyocytes have the capacity to proliferate in response to a cardiac injury, contributing to the regeneration of the heart and its functional restoration ( Foglia and Poss, 2016 ). (frontiersin.org)
  • Electrocytes briefly co-express sarcomeric proteins, such as myosin and tropomyosin, and keratin, a protein not found in mature muscle. (biologists.com)
  • We found that swimming-induced exercise increased cardiomyocyte proliferation and that this response was also found under regenerating conditions, when exercise was performed either prior to and after ventricular cryoinjury (CI). (frontiersin.org)
  • They were also aware that electric organs are embryologically derived from striated muscle. (biologists.com)
  • He noted that electric organs pose a potential problem for the theory of evolution by natural selection since it is difficult to account for the adaptive value of a muscle in a transitional state no longer serving a contractile function, but perhaps not yet being a fully functional electric organ. (biologists.com)
  • Thus, we may paraphrase Darwin and ask: how do electric organs develop from muscle and how have they developed in each lineage? (biologists.com)
  • Lowered Notch1 expression resulted in no tadpole tail regeneration, and induced Notch1 expression was able to partially rescue tail regeneration in the form of notochord and spinal cord (but very little musculature. (wikipedia.org)
  • Once BMP expression was restored, Msx1 expression was also restored, and regeneration proceeded.19 Similar studies have shown similar results in mouse digit tip regeneration. (wikipedia.org)
  • After skin loss, rapid wound contraction was followed by hair follicle regeneration in dorsal skin wounds. (nature.com)
  • Maginnis, T. L. The costs of autotomy and regeneration in animals: a review and framework for future research. (nature.com)
  • Shargal, E., Rath-Wolfson, L., Kronfeld, N. & Dayan, T. Ecological and histological aspects of tail loss in spiny mice (Rodentia: Muridae, Acomys ) with a review of its occurrence in rodents. (nature.com)
  • The electric organ has evolved independently from muscle in at least six lineages of fish. (biologists.com)