| pseudotyped baculovirus is an effective gene expression tool for studying molecular function during axolotl limb regeneration. | axolotls can regenerate complex structures through recruitment and remodeling of cells within mature tissues. accessing the underlying mechanisms at a molecular resolution is crucial to understand how injury triggers regeneration and how it proceeds. however, gene transformation in adult tissues can be challenging. here we characterize the use of pseudotyped baculovirus (bv) as an effective gene transfer method both for cells within mature limb tissue and within the blastema. these cells remain ... | 0 | 29198566 |
| biology's beloved amphibian - the axolotl - is racing towards extinction. | | 2017 | 29144487 |
| transcriptome dynamics along axolotl regenerative development are consistent with an extensive reduction in gene expression heterogeneity in dedifferentiated cells. | although in recent years the study of gene expression variation in the absence of genetic or environmental cues or gene expression heterogeneity has intensified considerably, many basic and applied biological fields still remain unaware of how useful the study of gene expression heterogeneity patterns might be for the characterization of biological systems and/or processes. largely based on the modulator effect chromatin compaction has for gene expression heterogeneity and the extensive changes ... | 2017 | 29134148 |
| systemic cell cycle activation is induced following complex tissue injury in axolotl. | activation of progenitor cells is crucial to promote tissue repair following injury in adult animals. in the context of successful limb regeneration following amputation, progenitor cells residing within the stump must re-enter the cell cycle to promote regrowth of the missing limb. we demonstrate that in axolotls, amputation is sufficient to induce cell-cycle activation in both the amputated limb and the intact, uninjured contralateral limb. activated cells were found throughout all major tissu ... | 0 | 29111100 |
| transcriptional correlates of proximal-distal identify and regeneration timing in axolotl limbs. | cells within salamander limbs retain memories that inform the correct replacement of amputated tissues at different positions along the length of the arm, with proximal and amputations completing regeneration at similar times. we investigated the possibility that positional memory is associated with variation in transcript abundances along the proximal-distal limb axis. transcripts were deeply sampled from ambystoma mexicanum limbs at the time they were administered fore arm vs upper arm amputat ... | 2017 | 29107037 |
| efficient gene knockin in axolotl and its use to test the role of satellite cells in limb regeneration. | 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 ... | 2017 | 29087939 |
| salamander spinal cord regeneration: the ultimate positive control in vertebrate spinal cord regeneration. | repairing injured tissues / organs is one of the major challenges for the maintenance of proper organ function in adulthood. in mammals, the central nervous system including the spinal cord, once established during embryonic development, has very limited capacity to regenerate. in contrast, salamanders such as axolotls can fully regenerate the injured spinal cord, making this a very powerful vertebrate model system for studying this process. here we discuss the cellular and molecular requirement ... | 2017 | 29030146 |
| a new and improved algorithm for the quantification of chromatin condensation from microscopic data shows decreased chromatin condensation in regenerating axolotl limb cells. | the nuclear landscape plays an important role in the regulation of tissue and positional specific genes in embryonic and developing cells. changes in this landscape can be dynamic, and are associated with the differentiation of cells during embryogenesis, and the de-differentiation of cells during induced pluripotent stem cell (ipsc) formation and in many cancers. however, tools to quantitatively characterize these changes are limited, especially in the in vivo context, where numerous tissue typ ... | 2017 | 29023511 |
| propofol (2,6-diisopropylphenol) is an applicable immersion anesthetic in the axolotl with potential uses in hemodynamic and neurophysiological experiments. | the mexican axolotl (ambystoma mexicanum) is an important model species in regenerative biology. traditionally, axolotls are anesthetized using benzocaine or ms-222, both of which act to inhibit voltage gated sodium channels thereby preventing action potential propagation. in some neurophysiological experiments this is not desirable; therefore we tested propofol as an alternative anesthetic in the axolotl. we evaluated benzocaine, ms-222, and propofol's cardiovascular effects, effects on action ... | 2017 | 28975032 |
| inhibition of vascular endothelial growth factor receptor decreases regenerative angiogenesis in axolotls. | angiogenesis is crucial for tissue growth and repair in mammals, and is chiefly regulated by vascular endothelial growth factor (vegf) signaling. we evaluated the effect of chemical inhibition of vegf receptor signaling in animals with superior regenerative ability, axolotl salamanders, to determine the impact on vascularization and regenerative outgrowth. following tail amputation, treated animals (100 nm ptk787) and controls were examined microscopically and measured over the month-long period ... | 2017 | 28921926 |
| lineage tracing of genome-edited alleles reveals high fidelity axolotl limb regeneration. | salamanders are unparalleled among tetrapods in their ability to regenerate many structures, including entire limbs, and the study of this ability may provide insights into human regenerative therapies. the complex structure of the limb poses challenges to the investigation of the cellular and molecular basis of its regeneration. using crispr/cas, we genetically labelled unique cell lineages within the developing axolotl embryo and tracked the frequency of each lineage within amputated and fully ... | 2017 | 28917058 |
| comparison of tissue processing methods for microvascular visualization in axolotls. | the vascular system, the pipeline for oxygen and nutrient delivery to tissues, is essential for vertebrate development, growth, injury repair, and regeneration. with their capacity to regenerate entire appendages throughout their lifespan, axolotls are an unparalleled model for vertebrate regeneration, but they lack many of the molecular tools that facilitate vascular imaging in other animal models. the determination of vascular metrics requires high quality image data for the discrimination of ... | 2017 | 28913170 |
| novel axolotl cardiac function analysis method using magnetic resonance imaging. | the salamander axolotl is capable of complete regeneration of amputated heart tissue. however, non-invasive imaging tools for assessing its cardiac function were so far not employed. in this study, cardiac magnetic resonance imaging is introduced as a non-invasive technique to image heart function of axolotls. three axolotls were imaged with magnetic resonance imaging using a retrospectively gated fast low angle shot cine sequence. within one scanning session the axolotl heart was imaged three t ... | 2017 | 28837595 |
| tail regeneration and other phenomena of wound healing and tissue restoration in lizards. | wound healing is a fundamental evolutionary adaptation with two possible outcomes: scar formation or reparative regeneration. scars participate in re-forming the barrier with the external environment and restoring homeostasis to injured tissues, but are well understood to represent dysfunctional replacements. in contrast, reparative regeneration is a tissue-specific program that near-perfectly replicates that which was lost or damaged. although regeneration is best known from salamanders (includ ... | 2017 | 28814609 |
| dii perfusion as a method for vascular visualization in ambystoma mexicanum. | perfusion techniques have been used for centuries to visualize the circulation of tissues. axolotl (ambystoma mexicanum) is a species of salamander that has emerged as an essential model for regeneration studies. little is known about how revascularization occurs in the context of regeneration in these animals. here we report a simple method for visualization of the vasculature in axolotl via perfusion of 1,1'-dioctadecy-3,3,3',3'-tetramethylindocarbocyanine perchlorate (dii). dii is a lipophili ... | 2017 | 28654050 |
| advances in decoding axolotl limb regeneration. | humans and other mammals are limited in their natural abilities to regenerate lost body parts. by contrast, many salamanders are highly regenerative and can spontaneously replace lost limbs even as adults. because salamander limbs are anatomically similar to human limbs, knowing how they regenerate should provide important clues for regenerative medicine. although interest in understanding the mechanics of this process has never wavered, until recently researchers have been vexed by seemingly im ... | 2017 | 28648452 |
| ion channel signaling influences cellular proliferation and phagocyte activity during axolotl tail regeneration. | little is known about the potential for ion channels to regulate cellular behaviors during tissue regeneration. here, we utilized an amphibian tail regeneration assay coupled with a chemical genetic screen to identify ion channel antagonists that altered critical cellular processes during regeneration. inhibition of multiple ion channels either partially (anoctamin1/tmem16a, anoctamin2/tmem16b, kv2.1, kv2.2, l-type cav channels and h/k atpases) or completely (glyr, gabaar, kv1.5 and serca pumps) ... | 2017 | 28603004 |
| a retrospective study of diseases in ambystoma mexicanum: a report of 97 cases. | ambystoma mexicanum kept as pets are affected by a variety of diseases. however, no reports regarding the incidence of specific diseases are available. this study aimed to identify the diseases that occur frequently in this species by surveying the incidence of conditions in pet a. mexicanum specimens brought to a veterinary hospital. the sample comprised 97 pet a. mexicanum individuals brought to the authors' hospital during the 82-month period, i.e., from january 2008 to october 2014. in total ... | 2017 | 28529268 |
| senescence gives insights into the morphogenetic evolution of anamniotes. | senescence represents a mechanism to avoid undesired cell proliferation that plays a role in tumor suppression, wound healing and embryonic development. in order to gain insight on the evolution of senescence, we looked at its presence in developing axolotls (urodele amphibians) and in zebrafish (teleost fish), which are both anamniotes. our data indicate that cellular senescence is present in various developing structures in axolotls (pronephros, olfactory epithelium of nerve fascicles, lateral ... | 2017 | 28500032 |
| a brief history of the study of nerve dependent regeneration. | nerve dependence is a phenomenon observed across a stunning array of species and tissues. from zebrafish to fetal mice to humans, research across various animal models has shown that nerves are critical for the support of tissue repair and regeneration. although the study of this phenomenon has persisted for centuries, largely through research conducted in salamanders, the cellular and molecular mechanisms of nerve dependence remain poorly-understood. here we highlight the near-ubiquity and clin ... | 2017 | 28459075 |
| tissue regeneration in dentistry: can salamanders provide insight? | the ability to regenerate damaged tissues would be of tremendous benefit for medicine and dentistry. unfortunately, humans are unable to regenerate tissues such as teeth and fingers or to repair injured spinal cord. with an aging population, health problems are more prominent and dentistry is no exception as loss of bone tissue in the orofacial sphere from periodontal disease is on the rise. humans can repair oral soft tissues exceptionally well; however, hard tissues, such as bone and teeth, ar ... | 2017 | 28376251 |
| embryonic yolk removal affects neither morphology nor escape performance of larval axolotls. | maternal effects, the influences of maternal phenotype on the phenotypes of her offspring, mediate early ontogenetic traits through maternal investment. in amphibians, provisioning eggs with yolk is the main source of maternal investment. while larger eggs generally result in larger, higher-quality offspring, the relationship between egg size and offspring phenotype is complicated because offspring can evolve to be more or less responsive to variation in yolk provisions. previous studies of seve ... | 2017 | 28365231 |
| data on chemical activation of wnt/β-catenin during axolotl limb regeneration. | limb amputation in axolotls was performed to obtain data demonstrating that a chemical agonist of wnt (int-related protein)/β-catenin signalling can have a role in axolotl limb regeneration (wischin et al., 2017) [1]. the data revealed that active β-catenin protein was present during limb regeneration in some leydig cells in the epithelium; after the chemical treatment, it was observed in more leydig cells. in addition, the chemical agonist of wnt generated distinct limb malformation. | 2017 | 28349103 |
| diffusion tensor tractography reveals muscle reconnection during axolotl limb regeneration. | axolotls have amazing ability to regenerate their lost limbs. our previous works showed that after amputation the remnant muscle ends remained at their original location whilst sending satellite cells into the regenerating parts to develop into early muscle fibers in the late differentiation stage. the parental and the newly formed muscle fibers were not connected until very late stage. the present study used non-invasive diffusion tensor imaging (dti) to monitor weekly axolotl upper arm muscles ... | 2017 | 28253344 |
| repeated removal of developing limb buds permanently reduces appendage size in the highly-regenerative axolotl. | matching appendage size to body size is fundamental to animal function. generating an appropriately-sized appendage is a robust process executed during development which is also critical for regeneration. when challenged, larger animals are programmed to regenerate larger limbs than smaller animals within a single species. understanding this process has important implications for regenerative medicine. to approach this complex question, models with altered appendage size:body size ratios are req ... | 2017 | 28235582 |
| methylene blue assay for estimation of regenerative re-epithelialization in vivo. | the rapidity with which epithelial cells cover a wound surface helps determine whether scarring or scar-less healing results. as methylene blue is a vital dye that is absorbed by damaged tissue but not undamaged epidermis, it can be used to assess wound closure. we sought to develop a quantitative methylene blue exclusion assay to estimate the timeframe for re-epithelialization in regenerating appendages in zebrafish and axolotls, two classic model systems of regeneration. following application ... | 2017 | 28228166 |
| regrow like an axolotl. | | 2017 | 28183965 |
| chemical activation of wnt/β-catenin signalling inhibits innervation and causes skeletal tissue malformations during axolotl limb regeneration. | limb regeneration involves several interrelated physiological processes in which a particular signalling pathway may play a variety of functions. blocking the function of wnt/β-catenin signalling during limb regeneration inhibits regeneration in axolotls (ambystoma mexicanum). limb development shares many features with limb regeneration, and wnt/β-catenin activation has different effects depending on the developmental stage. the aim of this study was to evaluate whether wnt/β-catenin signalling ... | 2017 | 28163199 |
| oral-facial tissue reconstruction in the regenerative axolotl. | absence of large amounts of orofacial tissues caused by cancerous resections, congenital defects, or trauma results in sequelae such as dysphagia and noticeable scars. oral-neck tissue regeneration was studied in the axolotl (regenerative amphibian) following a 2.5-mm punch biopsy that simultaneously removed skin, connective tissue, muscle, and cartilage in the tongue and intermandibular region. the untreated wound was studied macroscopically and histologically at 17 different time points rangin ... | 2016 | 28121390 |
| a tissue-mapped axolotl de novo transcriptome enables identification of limb regeneration factors. | mammals have extremely limited regenerative capabilities; however, axolotls are profoundly regenerative and can replace entire limbs. the mechanisms underlying limb regeneration remain poorly understood, partly because the enormous and incompletely sequenced genomes of axolotls have hindered the study of genes facilitating regeneration. we assembled and annotated a de novo transcriptome using rna-sequencing profiles for a broad spectrum of tissues that is estimated to have near-complete sequence ... | 2017 | 28099853 |
| amphibase: a new genomic resource for non-model amphibian species. | more than five thousand genes annotated in the recently published xenopus laevis and xenopus tropicalis genomes do not have a candidate orthologous counterpart in other vertebrate species. to determine whether these sequences represent genuine amphibian-specific genes or annotation errors, it is necessary to analyze them alongside sequences from other amphibian species. however, due to large genome sizes and an abundance of repeat sequences, there are limited numbers of gene sequences available ... | 2017 | 28095648 |
| retinoic acid receptor regulation of epimorphic and homeostatic regeneration in the axolotl. | salamanders are capable of regenerating amputated limbs by generating a mass of lineage-restricted cells called a blastema. blastemas only generate structures distal to their origin unless treated with retinoic acid (ra), which results in proximodistal (pd) limb duplications. little is known about the transcriptional network that regulates pd duplication. in this study, we target specific retinoic acid receptors (rars) to either pd duplicate (ra treatment or rarγ agonist) or truncate (rarβ antag ... | 2017 | 28087637 |
| regulation of injury-induced ovarian regeneration by activation of oogonial stem cells. | some animals have the ability to generate large numbers of oocytes throughout life. this raises the question whether persistent adult germline stem cell populations drive continuous oogenesis and whether they are capable of mounting a regenerative response after injury. here we demonstrate the presence of adult oogonial stem cells (oscs) in the adult axolotl salamander ovary and show that ovarian injury induces osc activation and functional regeneration of the ovaries to reproductive capability. ... | 2017 | 28028909 |
| the posterior neural plate in axolotl gives rise to neural tube or turns anteriorly to form somites of the tail and posterior trunk. | classical grafting experiments in the mexican axolotl had shown that the posterior neural plate of the neurula is no specified neuroectoderm but gives rise to somites of the tail and posterior trunk. the bipotentiality of this region with neuromesodermal progenitor cell populations was revealed more recently also in zebrafish, chick, and mouse. we reinvestigated the potency of the posterior plate in axolotl using grafts from transgenic embryos, immunohistochemistry, and in situ hybridization. th ... | 2017 | 28017643 |
| mechanisms of vertebrate germ cell determination. | two unique characteristics of the germ line are the ability to persist from generation to generation and to retain full developmental potential while differentiating into gametes. how the germ line is specified that allows it to retain these characteristics within the context of a developing embryo remains unknown and is one focus of current research. germ cell specification proceeds through one of two basic mechanisms: cell autonomous or inductive. here, we discuss how germ plasm driven germ ce ... | 2017 | 27975276 |
| joint encoding of object motion and motion direction in the salamander retina. | the processing of motion in visual scenes is important for detecting and tracking moving objects as well as for monitoring self-motion through the induced optic flow. specialized neural circuits have been identified in the vertebrate retina for detecting motion direction or for distinguishing between object motion and self-motion, although little is known about how information about these distinct features of visual motion is combined. the salamander retina, which is a widely used model system f ... | 2016 | 27903729 |
| detailed tail proteomic analysis of axolotl (ambystoma mexicanum) using an mrna-seq reference database. | salamander axolotl has been emerging as an important model for stem cell research due to its powerful regenerative capacity. several advantages, such as the high capability of advanced tissue, organ, and appendages regeneration, promote axolotl as an ideal model system to extend our current understanding on the mechanisms of regeneration. acknowledging the common molecular pathways between amphibians and mammals, there is a great potential to translate the messages from axolotl research to mamma ... | 2017 | 27896924 |
| conserved and novel functions of programmed cellular senescence during vertebrate development. | cellular senescence, a form of stable cell cycle arrest that is traditionally associated with tumour suppression, has been recently found to occur during mammalian development. here, we show that cell senescence is an intrinsic part of the developmental programme in amphibians. programmed senescence occurs in specific structures during defined time windows during amphibian development. it contributes to the physiological degeneration of the amphibian pronephros and to the development of the ceme ... | 2017 | 27888193 |
| accelerated cell divisions drive the outgrowth of the regenerating spinal cord in axolotls. | axolotls are unique in their ability to regenerate the spinal cord. however, the mechanisms that underlie this phenomenon remain poorly understood. previously, we showed that regenerating stem cells in the axolotl spinal cord revert to a molecular state resembling embryonic neuroepithelial cells and functionally acquire rapid proliferative divisions (rodrigo albors et al., 2015). here, we refine the analysis of cell proliferation in space and time and identify a high-proliferation zone in the re ... | 2016 | 27885987 |
| re-epithelialization of large wound in paedomorphic and metamorphic axolotls. | axolotls (ambystoma mexicanum) may heal their skin wounds scar-free in both paedomorphs and metamorphs. in previous studies on small punch skin wounds, rapid re-epithelialisation was noted in these two axolotl morphs. however, large wound size in mammals may affect wound healing. in this study, large circumferential full thickness excision wounds on the hind limbs were created on juvenile paedomorphic and metamorphic axolotls. the results showed re-epithelialisation was more quickly initiated in ... | 2017 | 27859516 |
| live imaging of axolotl digit regeneration reveals spatiotemporal choreography of diverse connective tissue progenitor pools. | connective tissues-skeleton, dermis, pericytes, fascia-are a key cell source for regenerating the patterned skeleton during axolotl appendage regeneration. this complexity has made it difficult to identify the cells that regenerate skeletal tissue. inability to identify these cells has impeded a mechanistic understanding of blastema formation. by tracing cells during digit tip regeneration using brainbow transgenic axolotls, we show that cells from each connective tissue compartment have distinc ... | 2016 | 27840105 |
| multiplicity of buc copies in atlantic salmon contrasts with loss of the germ cell determinant in primates, rodents and axolotl. | the primordial germ cells (pgcs) giving rise to gametes are determined by two different mechanisms in vertebrates. while the germ cell fate in mammals and salamanders is induced by zygotic signals, maternally delivered germ cell determinants specify the pgcs in birds, frogs and teleost fish. assembly of the germ plasm in the oocyte is organized by the single buc in zebrafish, named velo1 in xenopus, and by oskar in drosophila. secondary loss of oskar in several insect lineages coincides with cha ... | 2016 | 27784263 |
| a histological atlas of the tissues and organs of neotenic and metamorphosed axolotl. | axolotl (ambystoma mexicanum) has been emerging as a promising model in stem cell and regeneration researches due to its exceptional regenerative capacity. although it represents lifelong lasting neoteny, induction to metamorphosis with thyroid hormones (ths) treatment advances the utilization of axolotl in various studies. it has been reported that amphibians undergo anatomical and histological remodeling during metamorphosis and this transformation is crucial for adaptation to terrestrial cond ... | 2016 | 27436816 |
| beryllium nitrate inhibits fibroblast migration to disrupt epimorphic regeneration. | epimorphic regeneration proceeds with or without formation of a blastema, as observed for the limb and skin, respectively. inhibition of epimorphic regeneration provides a means to interrogate the cellular and molecular mechanisms that regulate it. in this study, we show that exposing amputated limbs to beryllium nitrate disrupts blastema formation and causes severe patterning defects in limb regeneration. in contrast, exposing full-thickness skin wounds to beryllium only causes a delay in skin ... | 2016 | 27578793 |
| convergent evolutionary reduction of atrial septation in lungless salamanders. | nearly two thirds of the approximately 700 species of living salamanders are lungless. these species respire entirely through the skin and buccopharyngeal mucosa. lung loss dramatically impacts the configuration of the circulatory system but the effects of evolutionary lung loss on cardiac morphology have long been controversial. for example, there is presumably little need for an atrial septum in lungless salamanders due to the absence of pulmonary veins and the presence of a single source of m ... | 2017 | 27558020 |
| activation of smad2 but not smad3 is required to mediate tgf-β signaling during axolotl limb regeneration. | axolotls are unique among vertebrates in their ability to regenerate tissues, such as limbs, tail and skin. the axolotl limb is the most studied regenerating structure. the process is well characterized morphologically; however, it is not well understood at the molecular level. we demonstrate that tgf-β1 is highly upregulated during regeneration and that tgf-β signaling is necessary for the regenerative process. we show that the basement membrane is not prematurely formed in animals treated with ... | 2016 | 27549395 |
| histological image data of limb skeletal tissue from larval and adult ambystoma mexicanum. | the data presented in this article are related to the article entitled "cartilage and bone cells do not participate in skeletal regeneration in ambystoma mexicanum limbs" [1]. here we present image data of the post-embryonic development of the forelimb skeletal tissue of ambystoma mexicanum. histological staining was performed on sections from the intact limbs of young (6.5 cm) and old (25 cm) animals, and on dissected skeletal tissues (cartilage, bone, and periosteum) from these animals. | 2016 | 27547798 |
| liver histological changes and lipid peroxidation in the amphibian ambystoma mexicanum induced by sediment elutriates from the lake xochimilco. | lacustrine sediments accumulate pollutants that input from the lake watershed and can be released to the water column by sediment resuspension; thus, pollutants can change their bioavailability and exert adverse effects to aquatic biota. shallow-urban lakes are particularly susceptible to receive pollutants from urban discharges and sediment resuspension. lake xochimilco, in mexico city, an urban-shallow lake, faces multiple problems: urban sprawl, overexploitation of aquifers, drying of springs ... | 2016 | 27521947 |
| genome-wide analysis reveals conserved transcriptional responses downstream of resting potential change in xenopus embryos, axolotl regeneration, and human mesenchymal cell differentiation. | endogenous bioelectric signaling via changes in cellular resting potential (v mem) is a key regulator of patterning during regeneration and embryogenesis in numerous model systems. depolarization of v mem has been functionally implicated in dedifferentiation, tumorigenesis, anatomical re-specification, and appendage regeneration. however, no unbiased analyses have been performed to understand genome-wide transcriptional responses to v mem change in vivo. moreover, it is unknown which genes or ge ... | 2016 | 27499876 |
| positional information in axolotl and mouse limb extracellular matrix is mediated via heparan sulfate and fibroblast growth factor during limb regeneration in the axolotl (ambystoma mexicanum). | urodele amphibians are unique among adult vertebrates in their ability to regenerate complex body structures after traumatic injury. in salamander regeneration, the cells maintain a memory of their original position and use this positional information to recreate the missing pattern. we used an in vivo gain-of-function assay to determine whether components of the extracellular matrix (ecm) have positional information required to induce formation of new limb pattern during regeneration. we discov ... | 2015 | 27499874 |
| myocardial plasticity: cardiac development, regeneration and disease. | the adult mammalian heart is unable to recover from myocardial cell loss due to cardiac ischemia and infarction because terminally differentiated cardiomyocytes proliferate at a low rate. however, cardiomyocytes in other vertebrate animal models such as zebrafish, axolotls, newts and mammalian mouse neonates are capable of de-differentiating in order to promote cardiomyocyte proliferation and subsequent cardiac regeneration after injury. although de-differentiation may occur in adult mammalian c ... | 2016 | 27498024 |
| analysis of embryonic development in the unsequenced axolotl: waves of transcriptomic upheaval and stability. | the axolotl (ambystoma mexicanum) has long been the subject of biological research, primarily owing to its outstanding regenerative capabilities. however, the gene expression programs governing its embryonic development are particularly underexplored, especially when compared to other amphibian model species. therefore, we performed whole transcriptome polya+ rna sequencing experiments on 17 stages of embryonic development. as the axolotl genome is unsequenced and its gene annotation is incomple ... | 2017 | 27475628 |
| fgf and bmp derived from dorsal root ganglia regulate blastema induction in limb regeneration in ambystoma mexicanum. | urodele amphibians have a remarkable organ regeneration ability that is regulated by neural inputs. the identification of these neural inputs has been a challenge. recently, fibroblast growth factor (fgf) and bone morphogenic protein (bmp) were shown to substitute for nerve functions in limb and tail regeneration in urodele amphibians. however, direct evidence of fgf and bmp being secreted from nerve endings and regulating regeneration has not yet been shown. thus, it remained uncertain whether ... | 2016 | 27432514 |
| a concise review of common animal models for the study of limb regeneration. | correct selection of an appropriate animal mode to closely mimic human extremity diseases or to exhibit desirable phenotypes of limb regeneration is the first critical step for all scientists in biomedical and regenerative researches. the commonly-used animals in limb regeneration and repairing studies, such as axolotl, mice, and rats, are discussed in the review and other models including cockroaches, dogs, and horses are also mentioned. the review weighs the general advantages, disadvantages, ... | 2016 | 27391218 |
| a conserved microrna regulatory circuit is differentially controlled during limb/appendage regeneration. | although regenerative capacity is evident throughout the animal kingdom, it is not equally distributed throughout evolution. for instance, complex limb/appendage regeneration is muted in mammals but enhanced in amphibians and teleosts. the defining characteristic of limb/appendage regenerative systems is the formation of a dedifferentiated tissue, termed blastema, which serves as the progenitor reservoir for regenerating tissues. in order to identify a genetic signature that accompanies blastema ... | 2016 | 27355827 |
| could we also be regenerative superheroes, like salamanders? | development of methods to reawaken the semi-dormant regenerative potential that lies within adult human tissues would hold promise for the restoration of diseased or damaged organs and tissues. while most of the regeneration potential is suppressed in many vertebrates, including humans, during adult life, urodele amphibians (salamanders) retain their regenerative ability throughout adulthood. studies in newts and axolotls, two salamander models, have provided significant knowledge about adult li ... | 2016 | 27338874 |
| neuregulin-1 signaling is essential for nerve-dependent axolotl limb regeneration. | the mexican axolotl (ambystoma mexicanum) is capable of fully regenerating amputated limbs, but denervation of the limb inhibits the formation of the post-injury proliferative mass called the blastema. the molecular basis behind this phenomenon remains poorly understood, but previous studies have suggested that nerves support regeneration via the secretion of essential growth-promoting factors. an essential nerve-derived factor must be found in the blastema, capable of rescuing regeneration in d ... | 2016 | 27317805 |
| cartilage and bone cells do not participate in skeletal regeneration in ambystoma mexicanum limbs. | the mexican axolotl is one of the few tetrapod species that is capable of regenerating complete skeletal elements in injured adult limbs. whether the skeleton (bone and cartilage) plays a role in the patterning and contribution to the skeletal regenerate is currently unresolved. we tested the induction of pattern formation, the effect on cell proliferation, and contributions of skeletal tissues (cartilage, bone, and periosteum) to the regenerating axolotl limb. we found that bone tissue grafts f ... | 2016 | 27316294 |
| tissue- and time-directed electroporation of cas9 protein-grna complexes in vivo yields efficient multigene knockout for studying gene function in regeneration. | a rapid method for temporally and spatially controlled crispr-mediated gene knockout in vertebrates will be an important tool to screen for genes involved in complex biological phenomena like regeneration. here we show that in vivo injection of cas9 protein-guide rna (grna) complexes into the spinal cord lumen of the axolotl and subsequent electroporation leads to comprehensive knockout of sox2 gene expression in sox2+ neural stem cells with corresponding functional phenotypes from the gene knoc ... | 2016 | 29302334 |
| accessories to limb regeneration. | in a recent issue of nature, nacu et al. (2016) identified fgf and hh ligands as interacting molecular influences that are necessary and sufficient to induce the formation of supernumerary limbs from blastemal tissue in axolotl salamanders. | 2016 | 27219058 |
| gene expression during the first 28 days of axolotl limb regeneration i: experimental design and global analysis of gene expression. | while it is appreciated that global gene expression analyses can provide novel insights about complex biological processes, experiments are generally insufficiently powered to achieve this goal. here we report the results of a robust microarray experiment of axolotl forelimb regeneration. at each of 20 post-amputation time points, we estimated gene expression for 10 replicate rna samples that were isolated from 1 mm of heterogeneous tissue collected from the distal limb tip. we show that the lim ... | 2015 | 27168937 |
| adult axolotls can regenerate original neuronal diversity in response to brain injury. | the axolotl can regenerate multiple organs, including the brain. it remains, however, unclear whether neuronal diversity, intricate tissue architecture, and axonal connectivity can be regenerated; yet, this is critical for recovery of function and a central aim of cell replacement strategies in the mammalian central nervous system. here, we demonstrate that, upon mechanical injury to the adult pallium, axolotls can regenerate several of the populations of neurons present before injury. notably, ... | 2016 | 27156560 |
| expression analysis of baf60c during heart regeneration in axolotls and neonatal mice. | some organisms, such as zebrafish, urodele amphibians, and newborn mice, have a capacity for heart regeneration following injury. however, adult mammals fail to regenerate their hearts. to know why newborn mice can regenerate their hearts, we focused on epigenetic factors, which are involved in cell differentiation in many tissues. baf60c (brg1/brm-associated factor 60c), a component of atp-dependent chromatin-remodeling complexes, has an essential role for cardiomyocyte differentiation at the e ... | 2016 | 27125315 |
| fgf8 and shh substitute for anterior-posterior tissue interactions to induce limb regeneration. | in salamanders, grafting of a left limb blastema onto a right limb stump yields regeneration of three limbs, the normal limb and two 'supernumerary' limbs. this experiment and other research have shown that the juxtaposition of anterior and posterior limb tissue plus innervation are necessary and sufficient to induce complete limb regeneration in salamanders. however, the cellular and molecular basis of the requirement for anterior-posterior tissue interactions were unknown. here we have clarifi ... | 2016 | 27120163 |
| the role of stem cells in limb regeneration. | limb regeneration is a complex yet fascinating process observed to some extent in many animal species, though seen in its entirety in urodele amphibians. accomplished by formation of a morphologically uniform intermediate, the blastema, scientists have long attempted to define the cellular constituents that enable regrowth of a functional appendage. today, we know that the blastema consists of a variety of multipotent progenitor cells originating from a variety of tissues, and which contribute t ... | 2016 | 27008101 |
| multicellular mathematical modelling of mesendoderm formation in amphibians. | the earliest cell fate decisions in a developing embryo are those associated with establishing the germ layers. the specification of the mesoderm and endoderm is of particular interest as the mesoderm is induced from the endoderm, potentially from an underlying bipotential group of cells, the mesendoderm. mesendoderm formation has been well studied in an amphibian model frog, xenopus laevis, and its formation is driven by a gene regulatory network (grn) induced by maternal factors deposited in t ... | 2016 | 26934886 |
| marcks-like protein is an initiating molecule in axolotl appendage regeneration. | identifying key molecules that launch regeneration has been a long-sought goal. multiple regenerative animals show an initial wound-associated proliferative response that transits into sustained proliferation if a considerable portion of the body part has been removed. in the axolotl, appendage amputation initiates a round of wound-associated cell cycle induction followed by continued proliferation that is dependent on nerve-derived signals. a wound-associated molecule that triggers the initial ... | 2016 | 26934225 |
| proteinaceous pheromone homologs identified from the cloacal gland transcriptome of a male axolotl, ambystoma mexicanum. | pheromones play an important role in modifying vertebrate behavior, especially during courtship and mating. courtship behavior in urodele amphibians often includes female exposure to secretions from the cloacal gland, as well as other scent glands. the first vertebrate proteinaceous pheromone discovered, the decapeptide sodefrin, is a female attracting pheromone secreted by the cloacal gland of male cynops pyrrhogaster. other proteinaceous pheromones in salamanders have been shown to elicit resp ... | 2016 | 26885665 |
| courtship pheromone use in a model urodele, the mexican axolotl (ambystoma mexicanum). | sex pheromones have been shown to constitute a crucial aspect of salamander reproduction. until now, courtship pheromones of salamandridae and plethodontidae have been intensively studied, but information on chemical communication in other urodelan families is essentially lacking. the axolotl (ambystoma mexicanum, ambystomatidae) has a courtship display that suggests a key role for chemical communication in the orchestration of its sexual behavior, but no sex pheromones have yet been characteriz ... | 2016 | 26842386 |
| localization of amylin-like immunoreactivity in melanocyte-stimulating hormone-containing cells of the pars intermedia but not those of the pars distalis in the axolotl (ambystoma mexicanum) pituitary. | immunohistochemical techniques were employed to investigate the distribution of amylin-like immunoreactivity in the axolotl (ambystoma mexicanum) pituitary. amylin-immunoreactive cells were observed in the pars intermedia, and these cells were found to be immunoreactive for α-melanocyte-stimulating hormone (αmsh) as well. in contrast, αmsh-immunoreactive cells in the pars distalis were immuno-negaitive for amylin. these light microscopic findings were confirmed by immunoelectron microscopy. amyl ... | 2016 | 26797189 |
| tissue specific reactions to positional discontinuities in the regenerating axolotl limb. | we investigated cellular contributions to intercalary regenerates and 180° supernumerary limbs during axolotl limb regeneration using the cell autonomous gfp marker and exchanged blastemas between white and gfp animals. after distal blastemas were grafted to proximal levels tissues of the intercalary regenerate behaved independently with regard to the law of distal transformation; graft epidermis was replaced by stump epidermis, muscle-derived cells, blood vessels and schwann cells of the distal ... | 2015 | 26755943 |
| a novel role for sall4 during scar-free wound healing in axolotl. | the human response to serious cutaneous damage is limited to relatively primitive wound healing, whereby collagenous scar tissue fills the wound bed. scars assure structural integrity at the expense of functional regeneration. in contrast, axolotls have the remarkable capacity to functionally regenerate full thickness wounds. here, we identified a novel role for sall4 in regulating collagen transcription after injury that is essential for perfect skin regeneration in axolotl. furthermore, we ide ... | 2016 | 28955504 |
| cooperative inputs of bmp and fgf signaling induce tail regeneration in urodele amphibians. | urodele amphibians have remarkable organ regeneration ability. they can regenerate not only limbs but also a tail throughout their life. it has been demonstrated that the regeneration of some organs are governed by the presence of neural tissues. for instance, limb regeneration cannot be induced without nerves. thus, identifying the nerve factors has been the primary focus in amphibian organ regeneration research. recently, substitute molecules for nerves in limb regeneration, bmp and fgfs, were ... | 2016 | 26703427 |
| cellular dynamics underlying regeneration of appropriate segment number during axolotl tail regeneration. | salamanders regenerate their tails after amputation anywhere along their length. how the system faithfully reconstitutes the original number of segments and length is not yet known. | 2015 | 26647066 |
| positional plasticity in regenerating amybstoma mexicanum limbs is associated with cell proliferation and pathways of cellular differentiation. | the endogenous ability to dedifferentiate, re-pattern, and re-differentiate adult cells to repair or replace damaged or missing structures is exclusive to only a few tetrapod species. the mexican axolotl is one example of these species, having the capacity to regenerate multiple adult structures including their limbs by generating a group of progenitor cells, known as the blastema, which acquire pattern and differentiate into the missing tissues. the formation of a limb regenerate is dependent o ... | 2015 | 26597593 |
| planar cell polarity-mediated induction of neural stem cell expansion during axolotl spinal cord regeneration. | axolotls are uniquely able to mobilize neural stem cells to regenerate all missing regions of the spinal cord. how a neural stem cell under homeostasis converts after injury to a highly regenerative cell remains unknown. here, we show that during regeneration, axolotl neural stem cells repress neurogenic genes and reactivate a transcriptional program similar to embryonic neuroepithelial cells. this dedifferentiation includes the acquisition of rapid cell cycles, the switch from neurogenic to pro ... | 2015 | 26568310 |
| initial characterization of the large genome of the salamander ambystoma mexicanum using shotgun and laser capture chromosome sequencing. | vertebrates exhibit substantial diversity in genome size, and some of the largest genomes exist in species that uniquely inform diverse areas of basic and biomedical research. for example, the salamander ambystoma mexicanum (the mexican axolotl) is a model organism for studies of regeneration, development and genome evolution, yet its genome is ~10× larger than the human genome. as part of a hierarchical approach toward improving genome resources for the species, we generated 600 gb of shotgun s ... | 2015 | 26553646 |
| changes in regenerative capacity through lifespan. | most organisms experience changes in regenerative abilities through their lifespan. during aging, numerous tissues exhibit a progressive decline in homeostasis and regeneration that results in tissue degeneration, malfunction and pathology. the mechanisms responsible for this decay are both cell intrinsic, such as cellular senescence, as well as cell-extrinsic, such as changes in the regenerative environment. understanding how these mechanisms impact on regenerative processes is essential to dev ... | 2015 | 26512653 |
| linking vertebral number to performance of aquatic escape responses in the axolotl (ambystoma mexicanum). | environmental conditions during early development in ectothermic vertebrates can lead to variation in vertebral number among individuals of the same species. it is often seen that individuals of a species raised at cooler temperatures have more vertebrae than individuals raised at warmer temperatures, although the functional consequences of this variation in vertebral number on swimming performance are relatively unclear. to investigate this relationship, we tested how vertebral number in axolot ... | 2015 | 26489369 |
| dynamic membrane depolarization is an early regulator of ependymoglial cell response to spinal cord injury in axolotl. | salamanders, such as the mexican axolotl, are some of the few vertebrates fortunate in their ability to regenerate diverse structures after injury. unlike mammals they are able to regenerate a fully functional spinal cord after injury. however, the molecular circuitry required to initiate a pro-regenerative response after spinal cord injury is not well understood. to address this question we developed a spinal cord injury model in axolotls and used in vivo imaging of labeled ependymoglial cells ... | 2015 | 26477559 |
| hyperbaric oxygen promotes proximal bone regeneration and organized collagen composition during digit regeneration. | oxygen is critical for optimal bone regeneration. while axolotls and salamanders have retained the ability to regenerate whole limbs, mammalian regeneration is restricted to the distal tip of the digit (p3) in mice, primates, and humans. our previous study revealed the oxygen microenvironment during regeneration is dynamic and temporally influential in building and degrading bone. given that regeneration is dependent on a dynamic and changing oxygen environment, a better understanding of the eff ... | 2015 | 26452224 |
| identification of conserved and novel micrornas during tail regeneration in the mexican axolotl. | the mexican axolotl salamander (ambystoma mexicanum) is one member of a select group of vertebrate animals that have retained the amazing ability to regenerate multiple body parts. in addition to being an important model system for regeneration, the axolotl has also contributed extensively to studies of basic development. while many genes known to play key roles during development have now been implicated in various forms of regeneration, much of the regulatory apparatus controlling the underlyi ... | 2015 | 26378530 |
| generation of axolotl hematopoietic chimeras. | wound repair is an extremely complex process that requires precise coordination between various cell types including immune cells. unfortunately, in mammals this usually results in scar formation instead of restoration of the original fully functional tissue, otherwise known as regeneration. various animal models like frogs and salamanders are currently being studied to determine the intracellular and intercellular pathways, controlled by gene expression, that elicit cell proliferation, differen ... | 2015 | 26366424 |
| immunodetection of telomerase-like immunoreactivity in normal and regenerating tail of amphibians suggests it is related to their regenerative capacity. | the high regenerative power of amphibians suggests that numerous signaling pathways remain active in larvae and adult tissues, including those stimulated by telomerases. the protein component of telomerase (tert) shows high amino acid homology in numerous vertebrates and we have utilized an antibody made for a lizard telomerase to detect a putative telomerase in amphibians tissues based on 60-75% epitope identity. western blotting studies indicate that telomerase is constitutionally present in n ... | 2015 | 26351773 |
| dna methylation dynamics regulate the formation of a regenerative wound epithelium during axolotl limb regeneration. | the formation of a blastema during regeneration of an axolotl limb involves important changes in the behavior and function of cells at the site of injury. one of the earliest events is the formation of the wound epithelium and subsequently the apical epidermal cap, which involves in vivo dedifferentiation that is controlled by signaling from the nerve. we have investigated the role of epigenetic modifications to the genome as a possible mechanism for regulating changes in gene expression pattern ... | 2015 | 26308461 |
| primordial germ cells: the first cell lineage or the last cells standing? | embryos of many animal models express germ line determinants that suppress transcription and mediate early germ line commitment, which occurs before the somatic cell lineages are established. however, not all animals segregate their germ line in this manner. the 'last cell standing' model describes primordial germ cell (pgc) development in axolotls, in which pgcs are maintained by an extracellular signalling niche, and germ line commitment occurs after gastrulation. here, we propose that this 's ... | 2015 | 26286941 |
| comparative analysis of cartilage marker gene expression patterns during axolotl and xenopus limb regeneration. | axolotls (ambystoma mexicanum) can completely regenerate lost limbs, whereas xenopus laevis frogs cannot. during limb regeneration, a blastema is first formed at the amputation plane. it is thought that this regeneration blastema forms a limb by mechanisms similar to those of a developing embryonic limb bud. furthermore, xenopus laevis frogs can form a blastema after amputation; however, the blastema results in a terminal cone-shaped cartilaginous structure called a "spike." the causes of this p ... | 2015 | 26186213 |
| regeneration inducers in limb regeneration. | limb regeneration ability, which can be observed in amphibians, has been investigated as a representative phenomenon of organ regeneration. recently, an alternative experimental system called the accessory limb model was developed to investigate early regulation of amphibian limb regeneration. the accessory limb model contributed to identification of limb regeneration inducers in urodele amphibians. furthermore, the accessory limb model may be applied to other species to explore universality of ... | 2015 | 26100345 |
| the axolotl fibula as a model for the induction of regeneration across large segment defects in long bones of the extremities. | we tested the ability of the axolotl (ambystoma mexicanum) fibula to regenerate across segment defects of different size in the absence of intervention or after implant of a unique 8-braid pig small intestine submucosa (sis) scaffold, with or without incorporated growth factor combinations or tissue protein extract. fractures and defects of 10% and 20% of the total limb length regenerated well without any intervention, but 40% and 50% defects failed to regenerate after either simple removal of b ... | 2015 | 26098852 |
| using ambystoma mexicanum (mexican axolotl) embryos, chemical genetics, and microarray analysis to identify signaling pathways associated with tissue regeneration. | amphibian vertebrates are important models in regenerative biology because they present exceptional regenerative capabilities throughout life. however, it takes considerable effort to rear amphibians to juvenile and adult stages for regeneration studies, and the relatively large sizes that frogs and salamanders achieve during development make them difficult to use in chemical screens. here, we introduce a new tail regeneration model using late stage mexican axolotl embryos. we show that axolotl ... | 2015 | 26092703 |
| mesodermal origin of median fin mesenchyme and tail muscle in amphibian larvae. | mesenchyme is an embryonic precursor tissue that generates a range of structures in vertebrates including cartilage, bone, muscle, kidney, and the erythropoietic system. mesenchyme originates from both mesoderm and the neural crest, an ectodermal cell population, via an epithelial to mesenchymal transition (emt). because ectodermal and mesodermal mesenchyme can form in close proximity and give rise to similar derivatives, the embryonic origin of many mesenchyme-derived tissues is still unclear. ... | 2015 | 26086331 |
| epidermal closure regulates histolysis during mammalian (mus) digit regeneration. | mammalian digit regeneration progresses through consistent stages: histolysis, inflammation, epidermal closure, blastema formation, and finally redifferentiation. what we do not yet know is how each stage can affect others. questions of stage timing, tissue interactions, and microenvironmental states are becoming increasingly important as we look toward solutions for whole limb regeneration. this study focuses on the timing of epidermal closure which, in mammals, is delayed compared to more rege ... | 2015 | 27499872 |
| dual embryonic origin and patterning of the pharyngeal skeleton in the axolotl (ambystoma mexicanum). | the impressive morphological diversification of vertebrates was achieved in part by innovation and modification of the pharyngeal skeleton. extensive fate mapping in amniote models has revealed a primarily cranial neural crest derivation of the pharyngeal skeleton. although comparable fate maps of amphibians produced over several decades have failed to document a neural crest derivation of ventromedial elements in these vertebrates, a recent report provides evidence of a mesodermal origin of one ... | 2015 | 25963195 |
| recurrent turnover of senescent cells during regeneration of a complex structure. | cellular senescence has been recently linked to the promotion of age-related pathologies, including a decline in regenerative capacity. while such capacity deteriorates with age in mammals, it remains intact in species such as salamanders, which have an extensive repertoire of regeneration and can undergo multiple episodes through their lifespan. here we show that, surprisingly, there is a significant induction of cellular senescence during salamander limb regeneration, but that rapid and effect ... | 2015 | 25942455 |
| an aryl hydrocarbon receptor from the salamander ambystoma mexicanum exhibits low sensitivity to 2,3,7,8-tetrachlorodibenzo-p-dioxin. | structural features of the aryl hydrocarbon receptor (ahr) can underlie species- and population-specific differences in its affinity for 2,3,7,8-tetrachlorodibenzo-p-dioxin (tcdd). these differences often explain variations in tcdd toxicity. frogs are relatively insensitive to dioxin, and xenopus ahrs bind tcdd with low affinity. weak tcdd binding results from the combination of three residues in the ligand-binding domain: a354 and a370, and n325. here we sought to determine whether this mechani ... | 2015 | 25941739 |
| the history of the oldest self-sustaining laboratory animal: 150 years of axolotl research. | today the mexican axolotl is critically endangered in its natural habitat in lakes around mexico city, but thrives in research laboratories around the world, where it is used for research on development, regeneration, and evolution. here, we concentrate on the early history of the axolotl as a laboratory animal to celebrate that the first living axolotls arrived in paris in 1864, 150 years ago. maybe surprisingly, at first the axolotl was distributed across europe without being tied to specific ... | 2015 | 25920413 |
| analysis of signal processing in vestibular circuits with a novel light-emitting diodes-based fluorescence microscope. | optical visualization of neural network activity is limited by imaging system-dependent technical tradeoffs. to overcome these constraints, we have developed a powerful low-cost and flexible imaging system with high spectral variability and unique spatio-temporal precision for simultaneous optical recording and manipulation of neural activity of large cell groups. the system comprises eight high-power light-emitting diodes, a camera with a large metal-oxide-semiconductor sensor and a high numeri ... | 2015 | 25847143 |
| cooperative regulation of substrate stiffness and extracellular matrix proteins in skin wound healing of axolotls. | urodele amphibians (ambystoma mexicanum), unique among vertebrates, can regenerate appendages and other body parts entirely and functionally through a scar-free healing process. the wound epithelium covering the amputated or damaged site forms early and is essential for initiating the subsequent regenerative steps. however, the molecular mechanism through which the wound reepithelializes during regeneration remains unclear. in this study, we developed an in vitro culture system that mimics an in ... | 2015 | 25839038 |
| current advances in tissue repair and regeneration: the future is bright. | the fifth embo conference on 'the molecular and cellular basis of regeneration and repair' took place in the peaceful coastal town of sant feliu de guixols (spain) on september 2014. the meeting was organised by emili saló (u. barcelona, spain), kimberly mace (u. manchester, uk), patrizia ferretti (university college london, uk) and michael brand (centre for regenerative therapies dresden, germany) and received the generous support of society for developmental biology, the company of biologists, ... | 2015 | 27499870 |
| the axolotl limb blastema: cellular and molecular mechanisms driving blastema formation and limb regeneration in tetrapods. | the axolotl is one of the few tetrapods that are capable of regenerating complicated biological structures, such as complete limbs, throughout adulthood. 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. in this review we focus on the crucial early events that occur during wound healing, the neural-epithelial interactions that drive the forma ... | 2015 | 27499868 |