Publications

TitleAbstractYear
Filter
PMID(sorted descending)
Filter
gene expression patterns specific to the regenerating limb of the mexican axolotl.salamander limb regeneration is dependent upon tissue interactions that are local to the amputation site. communication among limb epidermis, peripheral nerves, and mesenchyme coordinate cell migration, cell proliferation, and tissue patterning to generate a blastema, which will form missing limb structures. an outstanding question is how cross-talk between these tissues gives rise to the regeneration blastema. to identify genes associated with epidermis-nerve-mesenchymal interactions during lim ...201223213371
regeneration of limb joints in the axolotl (ambystoma mexicanum).in spite of numerous investigations of regenerating salamander limbs, little attention has been paid to the details of how joints are reformed. an understanding of the process and mechanisms of joint regeneration in this model system for tetrapod limb regeneration would provide insights into developing novel therapies for inducing joint regeneration in humans. to this end, we have used the axolotl (mexican salamander) model of limb regeneration to describe the morphology and the expression patte ...201223185640
prominent role of prominin in the retina.prominin molecules represent a new family of pentaspan membrane glycoproteins expressed throughout the animal kingdom. the name originates from its localization on membrane protrusion, such as microvilli, filopodia, lamellipodia, and microspikes. following the original description in mouse and human, representative prominin members were found in fish (e.g., danio rerio), amphibian (ambystoma mexicanum, xenopus laevis), worm (caenorhabditis elegans), and flies (drosophila melanogaster). mammalian ...201323161075
association of modified cytosines and the methylated dna-binding protein mecp2 with distinctive structural domains of lampbrush chromatin.we have investigated the association of dna methylation and proteins interpreting methylation state with the distinctive closed and open chromatin structural domains that are directly observable in the lampbrush chromosomes (lbcs) of amphibian oocytes. to establish the distribution in lbcs of mecp2, one of the key proteins binding 5-methylcytosine-modified dna (5mc), we expressed ha-tagged mecp2 constructs in xenopus laevis oocytes. full-length mecp2 was predominantly targeted to the closed, tra ...201223149574
5-carboxylcytosine is localized to euchromatic regions in the nuclei of follicular cells in axolotl ovary.5-methylcytosine (5-mc) is an epigenetic modification associated with gene repression. recent studies demonstrated that 5-mc can be enzymatically oxidised into 5-hydroxymethylcytosine and further into 5-formylcytosine (5-fc) and 5-carboxylcytsine (5-cac). 5-cac has been found in embryonic stem cells and in mouse pre-implantation embryos but no detectable levels of this modification have been reported for somatic tissues to date. whereas it has been suggested that 5-cac can serve as an intermedia ...201723138778
muscle and connective tissue progenitor populations show distinct twist1 and twist3 expression profiles during axolotl limb regeneration.limb regeneration involves re-establishing a limb development program from cells within adult tissues. identifying molecular handles that provide insight into the relationship between cell differentiation status and cell lineage is an important step to study limb blastema cell formation. here, using single cell pcr, focusing on newly isolated twist1 sequences, we molecularly profile axolotl limb blastema cells using several progenitor cell markers. we link their molecular expression profile to t ...201323103585
a galvanotaxis assay for analysis of neural precursor cell migration kinetics in an externally applied direct current electric field.the discovery of neural stem and progenitor cells (collectively termed neural precursor cells) (npcs) in the adult mammalian brain has led to a body of research aimed at utilizing the multipotent and proliferative properties of these cells for the development of neuroregenerative strategies. a critical step for the success of such strategies is the mobilization of npcs toward a lesion site following exogenous transplantation or to enhance the response of the endogenous precursors that are found ...201223093363
microarray analysis of microrna expression during axolotl limb regeneration.among vertebrates, salamanders stand out for their remarkable capacity to quickly regrow a myriad of tissues and organs after injury or amputation. the limb regeneration process in axolotls (ambystoma mexicanum) has been well studied for decades at the cell-tissue level. while several developmental genes are known to be reactivated during this epimorphic process, less is known about the role of micrornas in urodele amphibian limb regeneration. given the compelling evidence that many micrornas ti ...201223028429
neuropeptide y enhances olfactory mucosa responses to odorant in hungry rats.neuropeptide y (npy) plays an important role in regulating appetite and hunger in vertebrates. in the hypothalamus, npy stimulates food intake under the control of the nutritional status. previous studies have shown the presence of npy and receptors in rodent olfactory system, and suggested a neuroproliferative role. interestingly, npy was also shown to directly modulate olfactory responses evoked by a food-related odorant in hungry axolotls. we have recently demonstrated that another nutritiona ...201223024812
evolution of electrosensory ampullary organs: conservation of eya4 expression during lateral line development in jawed vertebrates.the lateral line system of fishes and amphibians comprises two ancient sensory systems: mechanoreception and electroreception. electroreception is found in all major vertebrate groups (i.e. jawless fishes, cartilaginous fishes, and bony fishes); however, it was lost in several groups including anuran amphibians (frogs) and amniotes (reptiles, birds, and mammals), as well as in the lineage leading to the neopterygian clade of bony fishes (bowfins, gars, and teleosts). electroreception is mediated ...201723017075
anatomy of the pectoral and forelimb muscles of wildtype and green fluorescent protein-transgenic axolotls and comparison with other tetrapods including humans: a basis for regenerative, evolutionary and developmental studies.the axolotl ambystoma mexicanum is one of the most used model organisms in evolutionary, developmental and regenerative studies, particularly because it can reconstitute a fully functional and complete forelimb/hindlimb. surprisingly, there is no publication that describes all the pectoral and forelimb muscles of this species or provides a comparative framework between these muscles and those of other model organisms and of modern humans. in the present paper we describe and illustrate all these ...201222957800
histone deacetylases are required for amphibian tail and limb regeneration but not development.amphibians such as xenopus laevis and ambystoma mexicanum are capable of whole structure regeneration. however, transcriptional control over these events is not well understood. here, we investigate the role of histone deacetylase (hdac) enzymes in regeneration using hdac inhibitors. the class i/ii hdac inhibitor valproic acid (vpa) inhibits tail regeneration in embryos of the anuran amphibian xenopus laevis, confirming a recent report by others (tseng et al., 2011). this inhibition correlates w ...201522947425
early regulation of axolotl limb regeneration.amphibian limb regeneration has been studied for a long time. in amphibian limb regeneration, an undifferentiated blastema is formed around the region damaged by amputation. the induction process of blastema formation has remained largely unknown because it is difficult to study the induction of limb regeneration. the recently developed accessory limb model (alm) allows the investigation of limb induction and reveals early events of amphibian limb regeneration. the interaction between nerves and ...201222933482
reconstitution of the central nervous system during salamander tail regeneration from the implanted neurospheres.urodele amphibians such as axolotl are well known for their regenerative potential of the damaged central nervous system structures. upon tail amputation, neural stem cells behind the amputation plane undergo self-renewing divisions and contribute to the functional spinal cord in the newly formed regenerate. the neural stem cells, harboring this potential, can be isolated from the animal and cultured under the suspension conditions. after 2-3 weeks in vitro they will proliferate and form the flo ...201222914942
retrotransposon long interspersed nucleotide element-1 (line-1) is activated during salamander limb regeneration.salamanders possess an extraordinary capacity for tissue and organ regeneration when compared to mammals. in our effort to characterize the unique transcriptional fingerprint emerging during the early phase of salamander limb regeneration, we identified transcriptional activation of some germline-specific genes within the mexican axolotl (ambystoma mexicanum) that is indicative of cellular reprogramming of differentiated cells into a germline-like state. in this work, we focus on one of these ge ...201222913491
inducible genetic system for the axolotl.transgenesis promises a powerful means for assessing gene function during amphibian limb regeneration. this approach is complicated, however, by the need for embryonic appendage development to proceed unimpeded despite the genetic alterations one wishes to test later in the context of regeneration. achieving conditional gene regulation in this amphibian has not proved to be as straightforward as in many other systems. in this report we describe a unique method for obtaining temporal control over ...201222869739
activation of germline-specific genes is required for limb regeneration in the mexican axolotl.the capacity for tissue and organ regeneration in humans is dwarfed by comparison to that of salamanders. emerging evidence suggests that mechanisms learned from the early phase of salamander limb regeneration-wound healing, cellular dedifferentiation and blastemal formation-will reveal therapeutic approaches for tissue regeneration in humans. here we describe a unique transcriptional fingerprint of regenerating limb tissue in the mexican axolotl (ambystoma mexicanum) that is indicative of cellu ...201222841627
spatiotemporal regulation of keratin 5 and 17 in the axolotl limb.amphibians have greater regeneration capability than higher vertebrates. they can regenerate their limbs after an amputation. as a limb is regenerated, a regeneration-specific epithelium called the apical epithelial cap (aec) is induced. the aec is an essential structure for limb regeneration. despite the importance of the aec, molecular marker genes have not been well studied at the molecular level.201222836940
reconstitution of the central and peripheral nervous system during salamander tail regeneration.we show that after tail amputation in ambystoma mexicanum (axolotl) the correct number and spacing of dorsal root ganglia are regenerated. by transplantation of spinal cord tissue and nonclonal neurospheres, we show that the central spinal cord represents a source of peripheral nervous system cells. interestingly, melanophores migrate from preexisting precursors in the skin. finally, we demonstrate that implantation of a clonally derived spinal cord neurosphere can result in reconstitution of al ...201222829665
structural and functional analysis of intra-articular interzone tissue in axolotl salamanders.knowledge of mechanisms directing diarthrodial joint development may be useful in understanding joint pathologies and identifying new therapies. we have previously established that axolotl salamanders can fully repair large articular cartilage lesions, which may be due to the presence of an interzone-like tissue in the intra-articular space. study objectives were to further characterize axolotl diarthrodial joint structure and determine the differentiation potential of interzone-like tissue in a ...201222800772
cranial muscles in amphibians: development, novelties and the role of cranial neural crest cells.our research on the evolution of the vertebrate head focuses on understanding the developmental origins of morphological novelties. using a broad comparative approach in amphibians, and comparisons with the well-studied quail-chicken system, we investigate how evolutionarily conserved or variable different aspects of head development are. here we review research on the often overlooked development of cranial muscles, and on its dependence on cranial cartilage development. in general, cranial mus ...201322780231
visualization of retinoic acid signaling in transgenic axolotls during limb development and regeneration.retinoic acid (ra) plays a necessary role in limb development and regeneration, but the precise mechanism by which it acts during these processes is unclear. the role of ra in limb regeneration was first highlighted by the remarkable effect that it has on respecifying the proximodistal axis of the regenerating limb so that serially repeated limbs are produced. to facilitate the study of ra signaling during development and then during regeneration of the same structure we have turned to the axolo ...201222627291
nerve signaling regulates basal keratinocyte proliferation in the blastema apical epithelial cap in the axolotl (ambystoma mexicanum).the ability of adult vertebrates to repair tissue damage is widespread and impressive; however, the ability to regenerate structurally complex organs such as the limb is limited largely to the salamanders. the fact that most of the tissues of the limb can regenerate has led investigators to question and identify the barriers to organ regeneration. from studies in the salamander, it is known that one of the earliest steps required for successful regeneration involves signaling between nerves and ...201222537500
partial characterization of the sox2+ cell population in an adult murine model of digit amputation.tissue regeneration in response to injury in adult mammals is generally limited to select tissues. nonmammalian species such as newts and axolotls undergo regeneration of complex tissues such as limbs and digits via recruitment and accumulation of local and circulating multipotent progenitors preprogrammed to recapitulate the missing tissue. directed recruitment and activation of progenitor cells at a site of injury in adult mammals may alter the default wound-healing response from scar tissue t ...201222530556
muscle development and differentiation in the urodele ambystoma mexicanum.muscle differentiation has been widely described in zebrafish and xenopus, but nothing is known about this process in amphibian urodeles. both anatomical features and locomotor activity in urodeles are known to show intermediate features between fish and anurans. therefore, a better understanding of myogenesis in urodeles could be useful to clarify the evolutionary changes that led to the formation of skeletal muscle in the trunk of land vertebrates. we report here a detailed morphological and m ...201222519643
skin regeneration in adult axolotls: a blueprint for scar-free healing in vertebrates.while considerable progress has been made towards understanding the complex processes and pathways that regulate human wound healing, regenerative medicine has been unable to develop therapies that coax the natural wound environment to heal scar-free. the inability to induce perfect skin regeneration stems partly from our limited understanding of how scar-free healing occurs in a natural setting. here we have investigated the wound repair process in adult axolotls and demonstrate that they are c ...201222485136
semi-quantitative immunohistochemical detection of 5-hydroxymethyl-cytosine reveals conservation of its tissue distribution between amphibians and mammals.5-hydroxymethyl-cytosine (5-hmc) is a form of modified cytosine, which has recently attracted a considerable attention due to its potential role in transcriptional regulation. according to several reports 5-hydroxymethyl-cytosine distribution is tissue-specific in mammals. thus, 5-hmc is enriched in embryonic cell populations and in adult neuronal tissue. here, we describe a novel method of semi-quantitative immunohistochemical detection of 5-hmc and utilize it to assess the levels of this modif ...201222395462
collagen reconstitution is inversely correlated with induction of limb regeneration in ambystoma mexicanum.amphibians can regenerate missing body parts, including limbs. the regulation of collagen has been considered to be important in limb regeneration. collagen deposition is suppressed during limb regeneration, so we investigated collagen deposition and apical epithelial cap (aec) formation during axolotl limb regeneration. the accessory limb model (alm) has been developed as an alternative model for studying limb regeneration. using this model, we investigated the relationship between nerves, epid ...201222379987
cell movements of the deep layer of non-neural ectoderm underlie complete neural tube closure in xenopus.in developing vertebrates, the neural tube forms from a sheet of neural ectoderm by complex cell movements and morphogenesis. convergent extension movements and the apical constriction along with apical-basal elongation of cells in the neural ectoderm are thought to be essential for the neural tube closure (ntc) process. in addition, it is known that non-neural ectoderm also plays a crucial role in this process, as the neural tube fails to close in the absence of this tissue in chick and axolotl ...201222378637
elaphoidella grandidieri (harpacticoida: copepoda): demographic characteristics and possible use as live prey in aquaculture.in freshwater ecosystems, rotifers and cladocerans are ideal prey for fish larvae whereas copepods, due to their purported low growth rate and predatory tendency, are not. we recently isolated the parthenogenetic elaphoidella grandidieri (gueme et richard, 1893) a benthic freshwater harpacticoid, from a fish farm in the state of morelos, central mexico and tested its potential as a live prey organism for larval vertebrates. population growth and life table demography experiments were conducted, ...201122315830
the amazing, regenerating axolotl. 201222261883
ambiguities in the relationship between gonadal steroids and reproduction in axolotls (ambystoma mexicanum).axolotls (ambystoma mexicanum) are aquatic salamanders that are widely used in research. axolotls have been bred in laboratories for nearly 150 years, yet little is known about the basic biology of reproduction in these animals. we investigated the effects of changing day length, time of year, and food availability on levels of circulating estradiol and androgens in adult female and male axolotls, respectively. in addition, we examined the effects of these variables on the mass of ovaries, ovidu ...201222245262
CXCL14-like immunoreactivity in growth hormone-containing cells of urodele pituitaries.Immunohistochemical techniques were employed to investigate the distribution of a chemokine, namely, CXCL14-like immunoreactivity in the axolotl (Ambystoma mexicanum) and Japanese black salamander (Hynobius nigrescens) pituitaries. CXCL14-immunoreactive cells concentrated at an area of the pars distalis adjacent to the pars intermedia. We found that these cells correspond to the cells immunoreactive to an antibody against rat growth hormone (GH). Immunoelectron microscopy indicated that the CXCL ...201122119756
histology of plastic embedded amphibian embryos and larvae.amphibians including the south african clawed frog xenopus laevis, its close relative xenopus tropicalis, and the mexican axolotl (ambystoma mexicanum) are important vertebrate models for cell biology, development, and regeneration. for the analysis of embryos and larva with altered gene expression in gain-of-function or loss-of-function studies histology is increasingly important. here, we discuss plastic or resin embedding of embryos as valuable alternatives to conventional paraffin embedding. ...201122083609
esterases activity in the axolotl ambystoma mexicanum exposed to chlorpyrifos and its implication to motor activity.the axolotl ambystoma mexicanum is a neotenic salamander considered a good biological model due to its ability to regenerate limbs, tail, brain and heart cells. nevertheless, severe reduction of a. mexicanum wild populations in the lacustrine area of xochimilco, the natural habitat of the axolotl, could be related to several environmental pressures as the presence of organophosphate pesticides (opps), intensively applied in agricultural activities in xochimilco. thus the aim of this study was to ...201121996259
electrosensory ampullary organs are derived from lateral line placodes in bony fishes.electroreception is an ancient subdivision of the lateral line sensory system, found in all major vertebrate groups (though lost in frogs, amniotes and most ray-finned fishes). electroreception is mediated by 'hair cells' in ampullary organs, distributed in fields flanking lines of mechanosensory hair cell-containing neuromasts that detect local water movement. neuromasts, and afferent neurons for both neuromasts and ampullary organs, develop from lateral line placodes. although ampullary organs ...201121988912
immersion and branchial/transcutaneous irrigation anaesthesia with alfaxalone in a mexican axolotl.immersion anaesthetic techniques are commonly used in amphibian species. alfaxalone has been reported as an immersion anaesthetic in fish but not amphibians.201121988819
molecular and biochemical characterization of the mexican axolotl cd3 (cd3ε and cd3γ/δ).in mammals, the t-cell receptor (tcr) complex expressed on mature t-cells consists of α/β or γ/δ clonotypic heterodimers non-covalently associated with four invariant chains forming the cd3 complex (cd3γ, cd3δ, cd3ε and cd3ζ). the tcr is the unit implicated in the antigenic peptide recognition whereas the cd3 subunits present as three different dimers (δ-ε, γ-ε and ζ-ζ) in the receptor complex participate to the signal transduction and are indispensable for the expression of the tcr at the cell ...201121789595
the cellular basis for animal regeneration.the ability of animals to regenerate missing parts is a dramatic and poorly understood aspect of biology. the sources of new cells for these regenerative phenomena have been sought for decades. recent advances involving cell fate tracking in complex tissues have shed new light on the cellular underpinnings of regeneration in hydra, planarians, zebrafish, xenopus, and axolotl. planarians accomplish regeneration with use of adult pluripotent stem cells, whereas several vertebrates utilize a collec ...201121763617
a system for culturing iris pigment epithelial cells to study lens regeneration in newt.salamanders like newt and axolotl possess the ability to regenerate many of its lost body parts such as limbs, the tail with spinal cord, eye, brain, heart, the jaw¹. specifically, newts are unique for its lens regeneration capability. upon lens removal, ipe cells of the dorsal iris transdifferentiate to lens cells and eventually form a new lens in about a month²(,)³ . this property of regeneration is never exhibited by the ventral iris cells. the regeneration potential of the iris cells can be ...201121730940
the meis homeoprotein regulates the axolotl prod 1 promoter during limb regeneration.during limb regeneration in salamanders the blastemal cells give rise only to structures distal to the level of amputation. this proximodistal identity can be regulated by ectopic expression of meis homeoproteins or the three finger protein prod 1 which acts at the cell surface. it has been suggested that meis acts by regulating the transcription of prod 1. we have sequenced the axolotl prod 1 promoter and selected two candidate sites for binding meis homeoproteins. the sites were mutated in var ...201121684325
gene expression profile of the regeneration epithelium during axolotl limb regeneration.urodele amphibians are unique among adult vertebrates in their ability to regenerate missing limbs. the process of limb regeneration requires several key tissues including a regeneration-competent wound epidermis called the regeneration epithelium (re). we used microarray analysis to profile gene expression of the re in the axolotl, a mexican salamander. a list of 125 genes and expressed sequence tags (ests) showed a ≥1.5-fold expression in the re than in a wound epidermis covering a lateral cuf ...201121648017
absence of mutation at the 5'-upstream promoter region of the tpm4 gene from cardiac mutant axolotl (ambystoma mexicanum).tropomyosins are a family of actin-binding proteins that show cell-specific diversity by a combination of multiple genes and alternative rna splicing. of the 4 different tropomyosin genes, tpm4 plays a pivotal role in myofibrillogenesis as well as cardiac contractility in amphibians. in this study, we amplified and sequenced the upstream regulatory region of the tpm4 gene from both normal and mutant axolotl hearts. to identify the cis-elements that are essential for the expression of the tpm4, w ...201121626230
the yeast two hybrid system in a screen for proteins interacting with axolotl (ambystoma mexicanum) msx1 during early limb regeneration.urodele amphibians are exceptional in their ability to regenerate complex body structures such as limbs. limb regeneration depends on a process called dedifferentiation. under an inductive wound epidermis terminally differentiated cells transform to pluripotent progenitor cells that coordinately proliferate and eventually redifferentiate to form the new appendage. recent studies have developed molecular models integrating a set of genes that might have important functions in the control of regen ...201121571103
regeneration in vitro of axolotl peripheral and central axons.peripheral nerves and spinal cords of axolotls were maintained in organ culture for periods of up to 2 weeks. sensory axons in peripheral nerves and the dorsal funiculus of the spinal cord showed regeneration through the crush site within about 2 days. axonal regeneration also occurred in peripheral nerves after cutting but was dependent on close contact between proximal and distal stumps of nerve. when cells in the distal stump of nerve were killed by freezing, axonal regeneration was inhibited ...199021551566
blastema induction in aneurogenic state and prrx-1 regulation by mmps and fgfs in ambystoma mexicanum limb regeneration.urodele amphibians can regenerate amputated limbs. it has been considered that differentiated dermal tissues generate multipotent and undifferentiated cells called blastema cells during limb regeneration. in early phases of limb regeneration, blastema cells are induced by nerves and the apical epithelial cap (aec). we had previously investigated the role of neurotrophic factors in blastema or blastema-like formation consisting of prrx-1 positive cells. a new system suitable for investigating ear ...201121539833
pathological features of olfactory neuroblastoma in an axolotl (ambystoma mexicanum).a one-year-old, female mexican axolotl (ambystoma mexicanum) had a rough-surfaced, polypoid, pink tumor mass of approximately 10 mm in diameter in the oral cavity. histologically, the tumor extended from the ethmoturbinate region and into the oral cavity and had replaced some of the maxillary bone tissue. the tumor mass was composed of a lobular architecture of small round-shaped tumor cells with occasional flexner-wintersteiner-like rosette formation. there were no metastatic lesions in the oth ...201121519157
origin of amphibian and avian chromosomes by fission, fusion, and retention of ancestral chromosomes.amphibian genomes differ greatly in dna content and chromosome size, morphology, and number. investigations of this diversity are needed to identify mechanisms that have shaped the evolution of vertebrate genomes. we used comparative mapping to investigate the organization of genes in the mexican axolotl (ambystoma mexicanum), a species that presents relatively few chromosomes (n = 14) and a gigantic genome (>20 pg/n). we show extensive conservation of synteny between ambystoma, chicken, and hum ...201121482624
identification of differentially expressed thyroid hormone responsive genes from the brain of the mexican axolotl (ambystoma mexicanum).the mexican axolotl (ambystoma mexicanum) presents an excellent model to investigate mechanisms of brain development that are conserved among vertebrates. in particular, metamorphic changes of the brain can be induced in free-living aquatic juveniles and adults by simply adding thyroid hormone (t4) to rearing water. whole brains were sampled from juvenile a. mexicanum that were exposed to 0, 8, and 18days of 50nm t4, and these were used to isolate rna and make normalized cdna libraries for 454 d ...201121457787
network based transcription factor analysis of regenerating axolotl limbs.studies on amphibian limb regeneration began in the early 1700's but we still do not completely understand the cellular and molecular events of this unique process. understanding a complex biological process such as limb regeneration is more complicated than the knowledge of the individual genes or proteins involved. here we followed a systems biology approach in an effort to construct the networks and pathways of protein interactions involved in formation of the accumulation blastema in regener ...201121418574
distinct and conserved prominin-1/cd133-positive retinal cell populations identified across species.besides being a marker of various somatic stem cells in mammals, prominin-1 (cd133) plays a role in maintaining the photoreceptor integrity since mutations in the prom1 gene are linked with retinal degeneration. in spite of that, little information is available regarding its distribution in eyes of non-mammalian vertebrates endowed with high regenerative abilities. to address this subject, prominin-1 cognates were isolated from axolotl, zebrafish and chicken, and their retinal compartmentalizati ...201121407811
the axolotl model for regeneration and aging research: a mini-review.although regeneration of tissues occurs in all adult tetrapods, the ability to regenerate complex structures such as limbs is limited to urodeles (newts and salamanders). given that many of the biological processes and the signaling pathways that control these processes are highly conserved among all tetrapods, it is likely that humans have the potential to regenerate structures in the same way as salamanders. thus the remarkable regenerative abilities of salamanders demonstrate what we reasonab ...201121372551
glycated and carbamylated albumin are more "nephrotoxic" than unmodified albumin in the amphibian kidney.there is increasing evidence that proteins in tubular fluid are "nephrotoxic." in vivo it is difficult to study protein loading of tubular epithelial cells in isolation, i.e., without concomitant glomerular damage or changes of renal hemodynamics, etc. recently, a unique amphibian model has been described which takes advantage of the special anatomy of the amphibian kidney in which a subset of nephrons drains the peritoneal cavity (open nephrons) so that intraperitoneal injection of protein sele ...201121367923
dynamic expression of two thrombospondins during axolotl limb regeneration.the molecular processes underlying regeneration remain largely unknown. several potential factors have been elucidated by focusing on the regenerative function of genes originally identified in a developmental context. a complementary approach is to consider the roles of factors involved in wound healing. here we focus on the thrombospondins, a family of secreted extracellular matrix proteins that have been implicated in skin wound healing in mammals. we show that a subset of thrombospondins are ...201121360624
differential rna-binding activity of the hnrnp g protein correlated with the sex genotype in the amphibian oocyte.a proteomic approach has enabled the identification of an orthologue of the splicing factor hnrnp g in the amphibians xenopus tropicalis, ambystoma mexicanum, notophthalmus viridescens and pleurodeles walt, which shows a specific rna-binding affinity similar to that of the human hnrn g protein. three isoforms of this protein with a differential binding affinity for a specific rna probe were identified in the p. walt oocyte. in situ hybridization to lampbrush chromosomes of p. waltl revealed the ...201121278421
epigenetic reprogramming of breast cancer cells with oocyte extracts.breast cancer is a disease characterised by both genetic and epigenetic alterations. epigenetic silencing of tumour suppressor genes is an early event in breast carcinogenesis and reversion of gene silencing by epigenetic reprogramming can provide clues to the mechanisms responsible for tumour initiation and progression. in this study we apply the reprogramming capacity of oocytes to cancer cells in order to study breast oncogenesis.201121232089
evolution of the germ line-soma relationship in vertebrate embryos.the germ line and soma together maintain genetic lineages from generation to generation: the germ line passes genetic information between generations; the soma is the vehicle for germ line transmission, and is shaped by natural selection. the germ line and somatic lineages arise simultaneously in early embryos, but how their development is related depends on how primordial germ cells (pgc) are specified. pgcs are specified by one of two means. epigenesis describes the induction of pgcs from plur ...201121228047
a somitic contribution to the pectoral girdle in the axolotl revealed by long-term fate mapping.the pectoral girdle is a unique skeletal element that underwent drastic morphological changes during its evolution, especially in association with the fin-to-limb transition. comparative studies of its development are needed to gain a deeper understanding of its evolution. transplantation experiments using the quail-chick chimeric system have revealed that not only lateral plate mesoderm but also somites contribute to the pectoral girdle in birds. studies in mice and turtles also document somiti ...201121210942
evidence for an rna polymerization activity in axolotl and xenopus egg extracts.we have previously reported a post-transcriptional rna amplification observed in vivo following injection of in vitro synthesized transcripts into axolotl oocytes, unfertilized (ufe) or fertilized eggs. to further characterize this phenomenon, low speed extracts (lse) from axolotl and xenopus ufe were prepared and tested in an rna polymerization assay. the major conclusions are: i) the amphibian extracts catalyze the incorporation of radioactive ribonucleotide in rnase but not dnase sensitive pr ...201021203452
ambloxe--an epidermal lipoxygenase of the mexican axolotl in the context of amphibian regeneration and its impact on human wound closure in vitro.the mexican axolotl (ambystoma mexicanum) is a well-characterized example for intrinsic regeneration. as lipoxygenase signaling is of crucial importance to scarless mammalian wound healing, we postulated that lipoxygenases might be expressed during amphibian regeneration and they might also influence human cells under appropriate conditions. in this study we identified an amphibian lipoxygenase and evaluated its impact on human cells in an in vitro wound model.201121183847
severe necrotizing myocarditis caused by serratia marcescens infection in an axolotl (ambystoma mexicanum).this report provides the first account of the pathological changes associated with infection by serratia marcescens in an adult male axolotl. the infection resulted in septicaemia with severe multifocal necrotizing myocarditis. the latter lesion evolved to cardiac rupture, haemopericardium and death resulting from cardiac tamponade. this animal was exposed to higher than usual temperatures (24-25 °c) 2 weeks before the onset of disease and this may have resulted in immunocompromise and opportuni ...201021168146
regulation of proximal-distal intercalation during limb regeneration in the axolotl (ambystoma mexicanum).intercalation is the process whereby cells located at the boundary of a wound interact to stimulate proliferation and the restoration of the structures between the boundaries that were lost during wounding. thus, intercalation is widely considered to be the mechanism of regeneration. when a salamander limb is amputated, the entire cascade of regeneration events is activated, and the missing limb segments and their boundaries (joints) as well as the structures within each segment are regenerated. ...201021158757
functional and structural regeneration in the axolotl heart (ambystoma mexicanum) after partial ventricular amputation."in the present study we evaluated the effect of partial ventricular amputation (pva) in the heart of the adult urodele amphibian (ambystoma mexicanum) in vivo on spontaneous heart contractile activity recorded in vitro in association to the structural recovery at one, five, 30 and 90 days after injury. one day after pva, ventricular-tension (vt) (16 ± 3%), atrium-tension (at) (46 ± 4%) and heart rate (hr) (58+10%) resulted lower in comparison to control hearts. on days five, 30 and 90 after dam ...201021147570
matrix metalloproteinase expression during blastema formation in regeneration-competent versus regeneration-deficient amphibian limbs.we used an antibody array to compare the protein expression of matrix metalloproteinases (mmps)-1, -2, -3, -8, -9, -10, and -13, as well as the tissue inhibitors of metalloproteinases (timps)-1, -2, and -4 during blastema formation in amputated hindlimbs of regeneration-competent wild-type axolotls and stage-54 xenopus, and regeneration-deficient short-toes axolotls and xenopus froglets. expression of mmp-9 and -2 was also compared by zymography. both short-toes and froglet failed to up-regulate ...201121128310
from genes to neural tube defects (ntds): insights from multiscale computational modeling.the morphogenetic movements, and the embryonic phenotypes they ultimately produce, are the consequence of a series of events that involve signaling pathways, cytoskeletal components, and cell- and tissue-level mechanical interactions. in order to better understand how these events work together in the context of amphibian neurulation, an existing multiscale computational model was augmented. geometric data for this finite element-based mechanical model were obtained from 3d surface reconstructio ...201021119766
functional convergence of signalling by gpi-anchored and anchorless forms of a salamander protein implicated in limb regeneration.the gpi-anchor is an established determinant of molecular localisation and various functional roles have been attributed to it. the newt gpi-anchored three-finger protein (tfp) prod1 is an important regulator of cell behaviour during limb regeneration, but it is unclear how it signals to the interior of the cell. prod1 was expressed by transfection in cultured newt limb cells and activated transcription and expression of matrix metalloproteinase 9 (mmp9) by a pathway involving ligand-independent ...201121118959
intrinsic repair of full-thickness articular cartilage defects in the axolotl salamander.the ability to fully regenerate lost limbs has made the axolotl salamander (ambystoma mexicanum) a valuable model for studies of tissue regeneration. the current experiments investigate the ability of these vertebrates to repair large articular cartilage defects and restore normal hyaline cartilage and joint structure independent of limb amputation.201121115129
ikaros expression in tongue sole macrophages: a marker for lipopolysaccharide- and lipoteichoic acid-induced inflammatory responses.ikaros, an important transcription factor plays a role in the development of hemato-lymphoid system, yet its functional importance in fish macrophages remains unknown. in this study, an ikaros cdna was cloned from the half-smooth tongue sole cynoglossus semilaevis. the cdna contained an open reading frame of 1,290 nucleotides that encoded a 430 amino acid protein. the deduced protein is structurally similar to dul from other species, for example human, axolotl, and possesses 3-zinc finger and 2- ...201021069465
the ovaries in triploid axolotl females of different genotypes with respect to sex chromosomes. 194621020598
response of sex glands and secondary sex characters of zw and ww female axolotl larvae to testosterone propionate. 194621020499
centrifugal fibers in the optic nerve of the axolotl. 194521013407
differentiation of neuroblasts in the cavity of the nerve tube of axolotl larvae; tropisms of their fibers. 194521013406
collection of gametes from live axolotl, ambystoma mexicanum, and standardization of in vitro fertilization.this study established the first protocol for collection of gametes from live axolotl, ambystoma mexicanum, by gentle abdominal massage and in vitro fertilization. to stimulate spermiation and ovulation, human chorionic gonadotrophin (hcg) and ovopel pellets, which are commercially used to stimulate spawning in fish, were tested. the hcg was more effective than ovopel pellets and yielded a higher semen volume in the injected males and a shorter response time in the females. collected semen by th ...201020965554
applying amphibian limb regeneration to human wound healing: a review.in contrast to the limited regenerative ability found in human wound healing, which often results in unsatisfying and deficient scar formation, urodele amphibians, with the mexican axolotl as a prime example, expose an extraordinary regenerative capacity. this regeneration leads to a perfect restoration of tissue architecture, function, and aesthetics with the axolotl being actually able to reclaim complete limbs. evolutionary considerations suggest that regeneration might be a biologic principl ...201020948421
ex vivo generation of a functional and regenerative wound epithelium from axolotl (ambystoma mexicanum) skin.urodele amphibians (salamanders) are unique among adult vertebrates in their ability to regenerate structurally complete and fully functional limbs. regeneration is a stepwise process that requires interactions between keratinocytes, nerves and fibroblasts. the formation of a wound epithelium covering the amputation site is an early and necessary event in the process but the molecular mechanisms that underlie the role of the wound epithelium in regeneration remain unclear. we have developed an e ...201020874715
electron microscopy of the amphibian model systems xenopus laevis and ambystoma mexicanum.in this chapter we provide a set of different protocols for the ultrastructural analysis of amphibian (xenopus, axolotl) tissues, mostly of embryonic origin. for xenopus these methods include: (1) embedding gastrulae and tailbud embryos into spurr's resin for tem, (2) post-embedding labeling of methacrylate (k4m) and cryosections through adult and embryonic epithelia for correlative lm and tem, and (3) pre-embedding labeling of embryonic tissues with silver-enhanced nanogold. for the axolotl (am ...201020869532
epimorphic regeneration in mice is p53-independent.the process of regeneration is most readily studied in species of sponge, hydra, planarian and salamander (i.e., newt and axolotl). the closure of mrl mouse ear pinna through-and-through holes provides a mammalian model of unusual wound healing/regeneration in which a blastema-like structure closes the ear hole and cartilage and hair follicles are replaced. recent studies, based on a broad level of dna damage and a cell cycle pattern of g₂/m "arrest," showed that p21(cip1/waf1) was missing from ...201020855943
axolotl nanog activity in mouse embryonic stem cells demonstrates that ground state pluripotency is conserved from urodele amphibians to mammals.cells in the pluripotent ground state can give rise to somatic cells and germ cells, and the acquisition of pluripotency is dependent on the expression of nanog. pluripotency is conserved in the primitive ectoderm of embryos from mammals and urodele amphibians, and here we report the isolation of a nanog ortholog from axolotls (axnanog). axnanog does not contain a tryptophan repeat domain and is expressed as a monomer in the axolotl animal cap. the monomeric form is sufficient to regulate plurip ...201020736286
skin wound healing in axolotls: a scarless process.urodele amphibians, such as the axolotl (ambystoma mexicanum), have the unique faculty among vertebrates to regenerate lost appendages (limbs and tail) and other body parts (apex of the heart, forebrain and jaw) after amputation. interestingly, axolotls never seem to form scar tissue at the site of amputation once regeneration is completed. before now, very few studies were directly focused on the description of the events happening during wound healing after a skin injury in salamanders. in thi ...201020718005
microarray analysis of a salamander hopeful monster reveals transcriptional signatures of paedomorphic brain development.the mexican axolotl (ambystoma mexicanum) is considered a hopeful monster because it exhibits an adaptive and derived mode of development - paedomorphosis - that has evolved rapidly and independently among tiger salamanders. unlike related tiger salamanders that undergo metamorphosis, axolotls retain larval morphological traits into adulthood and thus present an adult body plan that differs dramatically from the ancestral (metamorphic) form. the basis of paedomorphic development was investigated ...201020584293
expression of a novel tropomyosin isoform in axolotl heart and skeletal muscle.tpm1kappa is an alternatively spliced isoform of the tpm1 gene whose specific role in cardiac development and disease is yet to be elucidated. although mrna studies have shown tpm1kappa expression in axolotl heart and skeletal muscle, it has not been quantified. also the presence of tpm1kappa protein in axolotl heart and skeletal muscle has not been demonstrated. in this study, we quantified tpm1kappa mrna expression in axolotl heart and skeletal muscle. using a newly developed tpm1kappa specifi ...201020564186
ion imaging during axolotl tail regeneration in vivo.several studies have reported that endogenous ion currents are involved in a wide range of biological processes from single cell and tissue behavior to regeneration. various methods are used to assess intracellular and local ion dynamics in biological systems, e.g., patch clamping and vibrating probes. here, we introduce an approach to detect ion kinetics in vivo using a noninvasive method that can electrophysiologically characterize an entire experimental tissue region or organism. ion-specific ...201020549718
lessons from the mexican axolotl: amphibian limb regeneration and its impact on plastic surgery. 201020517075
functional characterization of the vertebrate primary ureter: structure and ion transport mechanisms of the pronephric duct in axolotl larvae (amphibia).three kidney systems appear during vertebrate development: the pronephroi, mesonephroi and metanephroi. the pronephric duct is the first or primary ureter of these kidney systems. its role as a key player in the induction of nephrogenic mesenchyme is well established. here we investigate whether the duct is involved in urine modification using larvae of the freshwater amphibian ambystoma mexicanum (axolotl) as model.201020507566
a comparative study of gland cells implicated in the nerve dependence of salamander limb regeneration.limb regeneration in salamanders proceeds by formation of the blastema, a mound of proliferating mesenchymal cells surrounded by a wound epithelium. regeneration by the blastema depends on the presence of regenerating nerves and in earlier work it was shown that axons upregulate the expression of newt anterior gradient (nag) protein first in schwann cells of the nerve sheath and second in dermal glands underlying the wound epidermis. the expression of nag protein after plasmid electroporation wa ...201020456522
tissue factor expression in newt iris coincides with thrombin activation and lens regeneration.lens regeneration in adult salamanders occurs at the pupillary margin of the mid-dorsal iris where pigmented epithelial cells (pec) re-enter the cell cycle and transdifferentiate into lens. it is not understood how the injury caused by removal of the lens (lentectomy) in one location is linked to initiating the response in a different spatial location (dorsal iris) and to this particular sector. we propose that the blood provides a link between the localised coagulation and signal transduction p ...201720420902
a conserved mechanism for vertebrate mesoderm specification in urodele amphibians and mammals.understanding how mesoderm is specified during development is a fundamental issue in biology, and it has been studied intensively in embryos from xenopus. the gene regulatory network (grn) for xenopus is surprisingly complex and is not conserved in vertebrates, including mammals, which have single copies of the key genes nodal and mix. why the xenopus grn should express multiple copies of nodal and mix genes is not known. to understand how these expanded gene families evolved, we investigated me ...201020394741
a method for the analysis of organophosphorus pesticide residues in mexican axolotl.a method based on matrix solid-phase dispersion (mspd) was developed for quantitative extraction of three organophosphorus pesticides (opps) from the mexican axolotl, ambystoma mexicanum. the determination was carried out using high- performance liquid chromatography (hplc) with diode array spectrophotometric uv detection (dad). the mspd extraction with octadecylsilyl (c18) sorbent combined with a silica gel clean-up and acetonitrile elution was optimised for chlorpyrifos, fenthion and methyl pa ...201020390927
on the structure of the insegmented egg of axolotl and the origin of morphogenic prodromes. 194620292305
development and chromosome number of the offspring of a tetraploid axolotl female mated with a diploid male. 194720290903
on the influence of neurohypophysial elements on the sodium metabolism in axolotl. 194720262722
lack of p21 expression links cell cycle control and appendage regeneration in mice.animals capable of regenerating multiple tissue types, organs, and appendages after injury are common yet sporadic and include some sponge, hydra, planarian, and salamander (i.e., newt and axolotl) species, but notably such regenerative capacity is rare in mammals. the adult mrl mouse strain is a rare exception to the rule that mammals do not regenerate appendage tissue. certain commonalities, such as blastema formation and basement membrane breakdown at the wound site, suggest that mrl mice may ...201020231440
resection of a large intra-abdominal tumor in the mexican axolotl: a case report.this case report describes the surgical removal of an intra-abdominal tumor from a mexican axolotl (ambystoma mexicanum). the animal was admitted with left abdominal swelling that had increased over 4 months.201020210972
bmp-2 functions independently of shh signaling and triggers cell condensation and apoptosis in regenerating axolotl limbs.axolotls have the unique ability, among vertebrates, to perfectly regenerate complex body parts, such as limbs, after amputation. in addition, axolotls pattern developing and regenerating autopods from the anterior to posterior axis instead of posterior to anterior like all tetrapods studied to date. sonic hedgehog is important in establishing this anterior-posterior axis of limbs in all tetrapods including axolotls. interestingly, its expression is conserved (to the posterior side of limb buds ...201020152028
multiple sequences and factors are involved in stability/degradation of awnt-1, awnt-5a and awnt-5b mrnas during axolotl development.following fertilization in amphibian, early cleavage stages are maternally controlled at a post-transcriptional level before initiation of zygotic transcriptions at the mid blastula transition (mbt). we document the expression levels of the axolotl awnt-1, awnt-5a and awnt-5b genes as well as the adenylation states of their corresponding mrnas from the end of oogenesis until the tailbud stages. awnt-1/-5a rnas are stable until mbt then degraded before gastrulation. awnt-5b rnas are degraded at f ...201020151991
dermal fibroblasts contribute to multiple tissues in the accessory limb model.the accessory limb model has become an alternative model for performing investigations of limb regeneration in an amputated limb. in the accessory limb model, a complete patterned limb can be induced as a result of an interaction between the wound epithelium, a nerve and dermal fibroblasts in the skin. studies should therefore focus on examining these tissues. to date, however, a study of cellular contributions in the accessory limb model has not been reported. by using green fluorescent protein ...201020148925
induction of metamorphosis in axolotls (ambystoma mexicanum). 200920147244
axolotl (ambystoma mexicanum) limb and tail amputation. 200920147243
grafting axolotl (ambystoma mexicanum) limb skin and cartilage from gfp+ donors to normal hosts. 200920147242
axolotl (ambystoma mexicanum) embryonic transplantation methods. 200920147241
Refresh
firstprev
12345678910...
nextlast
Displaying items 401 - 500 of 1847