Publications

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proteolytic cleavage of acth in corticotropes of sexually mature axolotls (ambystoma mexicanum).immunohistochemical analysis of the pituitary of sexually mature axolotls revealed both acth(1-39)-related and alpha-msh-related immunoreactivity present in corticotropic cells located in the rostral anterior pituitary. gel filtration analysis indicated that the acth(1-39)-sized immunoreactivity and the alpha-msh-sized immunoreactivity detected in acid extracts of the axolotl anterior pituitary were present in a ratio in a range between 1:1 and 1:0.6. reversed-phase hplc analyses indicated that ...20078284252
ranavirus-associated mass mortality in imported red tailed knobby newts (tylototriton kweichowensis): a case report.a mass die-off of imported red tailed knobby newts (tylototriton kweichowensis) occurred in 2004 in belgium and the netherlands. in addition to massive infection with rhabdias tokyoensis, ranavirus was isolated from three dead newts examined virologically and the gene coding for the major capsid protein of the virus was sequenced. the isolate showed 99.8% similarity to the published sequence of frog virus 3. upon experimental infection of axolotls (ambystoma mexicanum) with this isolate, no mark ...200817449300
chytridiomycosis survey in wild and captive mexican amphibians.mexico, a rich country in terms of amphibian diversity, hosts about 375 described species. population declines have been documented for several species where it is evident that their habitat is being destroyed or modified. however, other species which inhabit pristine areas are declining as well. it has been suggested that the chytrid fungus batrachochytrium dendrobatidis (b.d.) may be one of the causes of the enigmatic declines in mexico. we surveyed a total of 45 localities, in 12 states acros ...200818648793
oleic acid loading does not add to the nephrotoxic effect of albumin in an amphibian and chronic rat model of kidney injury.under proteinuric conditions, ultrafiltrated albumin can induce an inflammatory and fibrotic response in proximal tubular cells. it is unclear whether albumin per se or compounds bound to albumin are nephrotoxic. some studies have supported the toxicity of albumin-bound fatty acids; however, these compared untreated, fatty acid containing, albumin and delipidated albumin. to prevent confounding by the delipidation procedure, we compared delipidated albumin and oleic acid (oa)-loaded delipidated ...200818653900
expression cloning of tmem16a as a calcium-activated chloride channel subunit.calcium-activated chloride channels (caccs) are major regulators of sensory transduction, epithelial secretion, and smooth muscle contraction. other crucial roles of caccs include action potential generation in characean algae and prevention of polyspermia in frog egg membrane. none of the known molecular candidates share properties characteristic of most caccs in native cells. using axolotl oocytes as an expression system, we have identified tmem16a as the xenopus oocyte cacc. the tmem16 family ...200818805094
chytridiomycosis in an aquarium collection of frogs: diagnosis, treatment, and control.the introduction of a new group of dendrobatid frogs to an established captive amphibian collection was followed by several acute mortalities in both resident and introduced frog populations. chytridiomycosis, caused by batrachochytrium dendrobatidis, was diagnosed by histology in two of the dead frogs. following the diagnosis, all amphibians were moved to a specially made quarantine room with strict handling protocols and treated with itraconazole. frogs, being terrestrial amphibians, were trea ...200818817004
pitx1 expression in developing and regenerating axolotl limbs.the expression of the homeobox transcription factor pitx1 was investigated in the mexican axolotl (ambystoma mexicanum) during limb development and regeneration by whole-mount mrna in situ hybridizations. this clone shares high amino acid identity with pitx1 from other vertebrates (92% xenopus; 87% chick; 75% human and mouse) within the region isolated. in the developing limbs, pitx1 was expressed in hindlimb mesenchyme, as has been reported in other species. the expression pattern in the hindli ...200818833906
transcriptional response of mexican axolotls to ambystoma tigrinum virus (atv) infection.very little is known about the immunological responses of amphibians to pathogens that are causing global population declines. we used a custom microarray gene chip to characterize gene expression responses of axolotls (ambystoma mexicanum) to an emerging viral pathogen, ambystoma tigrinum virus (atv).200818937860
working with oocyte nuclei: cytological preparations of active chromatin and nuclear bodies from amphibian germinal vesicles.the giant nucleus or germinal vesicle (gv) of amphibian oocytes presents a remarkable opportunity to examine nuclear structures in unprecedented levels of detail. by making use of spread preparations of gvs, it is possible to investigate the structure and function of transcription units in active chromatin and a variety of nuclear bodies, all within the limits of resolution of the light microscope. the basic method for producing gv spreads that is described here is based on simple manual dissect ...200818951160
effect of thyroid hormone concentration on the transcriptional response underlying induced metamorphosis in the mexican axolotl (ambystoma).thyroid hormones (th) induce gene expression programs that orchestrate amphibian metamorphosis. in contrast to anurans, many salamanders do not undergo metamorphosis in nature. however, they can be induced to undergo metamorphosis via exposure to thyroxine (t4). we induced metamorphosis in juvenile mexican axolotls (ambystoma mexicanum) using 5 and 50 nm t4, collected epidermal tissue from the head at four time points (days 0, 2, 12, 28), and used microarray analysis to quantify mrna abundances.200818267027
conserved pattern of otp-positive cells in the paraventricular nucleus and other hypothalamic sites of tetrapods.the paraventricular nucleus complex (pa) is a component of central neural circuitry that regulates several homeostatic variables. the paraventricular nucleus is composed of magnocellular neurons that project to the posterior pituitary and parvicellular neurons that project to numerous sites in the central nervous system. according to the revised prosomeric model, the paraventricular nucleus is located caudal to the eye stalk along the rostrocaudal dimension of the dorsal hypothalamic alar plate. ...200818331876
chondrogenesis and ossification of the lissamphibian pectoral girdle.knowledge of amphibian shoulder development is requisite for further understanding of gnathostome pectoral girdle evolution. fish and amniotes share few pectoral girdle elements, but modern amphibians exhibit a unique combination of traits that bridge the morphological gap between these two groups. i analyzed patterns of chondrogenesis, ossification, and bone histology of the pectoral girdles of two anuran species (xenopus laevis and bombina orientalis) and two urodele species (ambystoma mexican ...200817999401
electrogenic glutamate uptake is a major current carrier in the membrane of axolotl retinal glial cells.glutamate is taken up avidly by glial cells in the central nervous system. glutamate uptake may terminate the transmitter action of glutamate released from neurons, and keep extracellular glutamate at concentrations below those which are neurotoxic. we report here that glutamate evokes a large inward current in retinal glial cells which have their membrane potential and intracellular ion concentrations controlled by the whole-cell patch-clamp technique. this current seems to be due to an electro ...20082885752
mathematical model of the cupula-endolymph system with morphological parameters for the axolotl (ambystoma tigrinum) semicircular canals.by combining mathematical methods with the morphological analysis of the semicircular canals of the axolotl (ambystoma tigrinum), a system of differential equations describing the mechanical coupling in the semicircular canals was obtained. the coefficients of this system have an explicit physiological meaning that allows for the introduction of morphological and dynamical parameters directly into the differential equations. the cupula of the semicircular canals was modeled both as a piston and ...200819593455
the appearance of neural and glial cell markers during early development of the nervous system in the amphibian embryo.cell-type-specific antibodies have been used to follow the appearance of neurones and glia in the developing nervous system of the amphibian embryo. differentiated neurones were recognized with antibodies against neurofilament protein while glial cells were identified with antibodies against glial fibrillary acidic protein (gfap). the appearance of neurones containing the neurotransmitters 5-hydroxytryptamine and dopamine has been charted also. in xenopus, neurofilament protein in developing neu ...20082627893
a comparative proteomic analysis during urodele lens regeneration.to examine underlying mechanisms of urodele lens regeneration we have employed a proteomic analysis of 650 proteins involved in several signaling pathways. we compared expression of these proteins between the regeneration-competent dorsal iris and the regeneration-incompetent ventral iris in the newt. after a series of screenings we selected several proteins to evaluate their expression quantitatively on immunoblots. we then used these selected proteins to compare their expression between the do ...200818848527
regeneration in axolotls: a model to aim for!urodele amphibians such as the axolotl are the champions of tissue regeneration amongst vertebrates. these animals have mastered the ability to repair and replace most of their tissues following damage or amputation even well into adulthood. in fact it seems that the ability of these organisms to regenerate perfectly is not affected by their age. in addition to being able to regenerate, these animals display a remarkable resistance to cancer. they therefore represent a unique model organism to s ...200818814845
dual epithelial origin of vertebrate oral teeth.the oral cavity of vertebrates is generally thought to arise as an ectodermal invagination. consistent with this, oral teeth are proposed to arise exclusively from ectoderm, contributing to tooth enamel epithelium, and from neural crest derived mesenchyme, contributing to dentin and pulp. yet in many vertebrate groups, teeth are not restricted only to the oral cavity, but extend posteriorly as pharyngeal teeth that could be derived either directly from the endodermal epithelium, or from the ecto ...200818794902
glucose transporter distribution in the vessels of the central nervous system of the axolotl ambystoma mexicanum (urodela: ambystomatidae).the glut-1 isoform of the glucose transporter is commonly considered a reliable molecular marker of blood-brain barrier endothelia in the neural vasculature organized in a three-dimensional network of single vessels. the central nervous system of the axolotl ambystoma mexicanum is characterized by a vascular architecture that contains both single and paired vessels. the presence and distribution of the glut-1 transporter are studied in this urodele using both immunoperoxidase histochemistry and ...200818727107
identification of differentially expressed genes in 4-day axolotl limb blastema by suppression subtractive hybridization.the goal of our study was the identification of up-regulated genes during axolotl (ambystoma mexicanum) hindlimb regeneration 4 days after amputation using suppression subtractive hybridization (ssh). approximately 400 clones that harbored upregulated genes in regenerating blastema tissue were selected for sequence analysis. a blast homology search against ncbi non-redundant database and an ambystoma est database revealed 102 clones that showed homology to known sequences in genbank with annotat ...200818663994
a novel protein involved in heart development in ambystoma mexicanum is localized in endoplasmic reticulum.the discovery of the naturally occurring cardiac non-function (c) animal strain in ambystoma mexicanum (axolotl) provides a valuable animal model to study cardiomyocyte differentiation. in homozygous mutant animals (c/c), rhythmic contractions of the embryonic heart are absent due to a lack of organized myofibrils. we have previously cloned a partial sequence of a peptide cdna (n1) from an anterior-endoderm-conditioned-medium rna library that had been shown to be able to rescue the mutant phenot ...200818563628
neurotrophic regulation of epidermal dedifferentiation during wound healing and limb regeneration in the axolotl (ambystoma mexicanum).adult urodeles (salamanders) are unique in their ability to regenerate complex organs perfectly. the recently developed accessory limb model (alm) in the axolotl provides an opportunity to identify and characterize the essential signaling events that control the early steps in limb regeneration. the alm demonstrates that limb regeneration progresses in a stepwise fashion that is dependent on signals from the wound epidermis, nerves and dermal fibroblasts from opposite sides of the limb. when all ...200818533144
effects of nitrate on embryos of three amphibian species.embryos of three aquatic breeding amphibian species, ambystoma mexicanum, hyla chrysoscelis, and rana clamitans, were exposed to increasing levels (0, 5, 10, 30, 60, 100, 300, and 500 mg/l) of nitrate-n (no(3)-) in laboratory, static-renewal experiments. lethal effects were recorded from gosner stage 2 (h. chrysoscelis and r. clamitans) or harrison stage 2 (a. mexicanum) to time of hatching. date of hatching and length at hatching were also compared between treatments for a. mexicanum. no signif ...200818496633
multi-scale finite element modeling allows the mechanics of amphibian neurulation to be elucidated.the novel multi-scale computational approach introduced here makes possible a new means for testing hypotheses about the forces that drive specific morphogenetic movements. a 3d model based on this approach is used to investigate neurulation in the axolotl (ambystoma mexicanum), a type of amphibian. the model is based on geometric data from 3d surface reconstructions of live embryos and from serial sections. tissue properties are described by a system of cell-based constitutive equations, and pa ...200818408255
orexin-a immunoreactive cells and fibers in the central nervous system of the axolotl brain and their association with tyrosine hydroxylase and serotonin immunoreactive somata.orexin-a-like immunoreactivity in the axolotl brain was investigated by immunohistochemistry. immunoreactive somata formed a single group in the hypothalamus, but were distributed beyond several nuclei, namely, the ventral aspect of the nucleus preopticus posterior, dorsal aspect of the nucleus suprachiasmaticus and anterior aspect of the pars ventralis hypothalami. immunoreactive fibers were distributed throughout the brain from the olfactory bulb to the spinal cord except the cerebellum. the d ...200818378425
all about axolotls. 200818356918
analysis of the expression and function of wnt-5a and wnt-5b in developing and regenerating axolotl (ambystoma mexicanum) limbs.urodele amphibians are unique adult vertebrates because they are able to regenerate body parts after amputation. studies of urodele limb regeneration, the key model system for vertebrate regeneration, have led to an understanding of the origin of blastema cells and the importance of positional interactions between blastema cells in the control of growth and pattern formation. progress is now being made in the identification of the signaling pathways that regulate dedifferentiation, blastema morp ...200818336582
igx antibodies in the urodele amphibian ambystoma mexicanum.until recently, it was believed that urodele amphibians are able to synthesize only two immunoglobulin isotypes, igm and igy. we reinvestigated this issue in the iberian ribbed newt pleurodeles waltl and reported recently that this urodele expresses at least three isotypes: igm, igp and igy. in this study, we demonstrate that another urodele, ambystoma mexicanum, has also a third isotype whose amino acid sequence presents the highest homology with the amino acid sequence of xenopus igx. this iso ...200818280565
calcium waves.waves through living systems are best characterized by their speeds at 20 degrees c. these speeds vary from those of calcium action potentials to those of ultraslow ones which move at 1-10 and/or 10-20 nm s(-1). all such waves are known or inferred to be calcium waves. the two classes of calcium waves which include ones with important morphogenetic effects are slow waves that move at 0.2-2 microm s(-1) and ultraslow ones. both may be propagated by cycles in which the entry of calcium through the ...200818192175
bone morphogenetic protein-4 and noggin signaling regulates pigment cell distribution in the axolotl trunk.wild-type (dark) and white mutant axolotl (ambystoma mexicanum) embryos were used to investigate the role of the secreted growth factor bone morphogenetic protein-4 (bmp-4) and its antagonist, noggin, in dorso-lateral trunk neural crest (nc) migration. implantation of a bmp-4-coated microbead caused a melanophore-free zone around the bead, reduction of the dorsal fin above the bead, and disappearance of myotome tissue. we established a novel method that allows controlled induction of protein syn ...200817662068
regulation of dermal fibroblast dedifferentiation and redifferentiation during wound healing and limb regeneration in the axolotl.adult urodeles (salamanders) are unique in their ability to regenerate complex organs perfectly. the accessory limb model (alm) in the axolotl allows for the identification of signals from the wound epidermis, nerves and dermal fibroblasts that interact to regenerate a limb. in the present study, we have used the alm to identity the axolotl (ambystoma mexicanum) orthologue of twist (amtwist), a basic helix-loop-helix transcription factor that is involved in the regeneration of the dermis during ...200819046162
axolotl/newt. 200819030817
[changes in the sensitivity of axolotl eggs to the thermal action during maturation, fertilization and early cleavage]. 20085893410
[changes in sensitivity to heat in the embryonic development of axolotls]. 20085754704
organophosphorus pesticides effect on early stages of the axolotl ambystoma mexicanum (amphibia: caudata).ambystoma mexicanum is an endemic salamander of xochimilco, a wetland of the basin of mexico valley. nowadays, axolotl populations are decreasing due environmental stressors. particularly, studies about organophosphorus pesticides (opps; i.e. chlorpyrifos and malathion) toxicity are of great importance due to their intensive use in agricultural activities in xochimilco. thus, the aim of this study was to evaluate under controlled conditions the toxicity of chlorpyrifos (cpf) and malathion (mlt) ...200919012946
proteomic analysis of blastema formation in regenerating axolotl limbs.following amputation, urodele salamander limbs reprogram somatic cells to form a blastema that self-organizes into the missing limb parts to restore the structure and function of the limb. to help understand the molecular basis of blastema formation, we used quantitative label-free liquid chromatography-mass spectrometry/mass spectrometry (lc-ms/ms)-based methods to analyze changes in the proteome that occurred 1, 4 and 7 days post amputation (dpa) through the mid-tibia/fibula of axolotl hind li ...200919948009
coherent movement of cell layers during wound healing by image correlation spectroscopy.we have determined the complex sequence of events from the point of injury until reepithelialization in axolotl skin explant model and shown that cell layers move coherently driven by cell swelling after injury. we quantified three-dimensional cell migration using correlation spectroscopy and resolved complex dynamics such as the formation of dislocation points and concerted cell motion. we quantified relative behavior such as velocities and swelling of cells as a function of cell layer during h ...200919804742
detecting mitoses in time-lapse images of embryonic epithelia using intensity analysis.although the frequency and orientation of mitoses can significantly affect the mechanics of early embryo development, these data have not been available due to a shortage of suitable automated techniques. fluorescence imaging, though popular, requires biochemical intervention and is not always possible or desirable. here, a new technique that takes advantage of a localized intensity change that occurs in bright field images is used to identify mitoses. the algorithm involves mapping a deformable ...200919757061
myofibril-inducing rna (mir) is essential for tropomyosin expression and myofibrillogenesis in axolotl hearts.the mexican axolotl, ambystoma mexicanum, carries the naturally-occurring recessive mutant gene 'c' that results in a failure of homozygous (c/c) embryos to form hearts that beat because of an absence of organized myofibrils. our previous studies have shown that a noncoding rna, myofibril-inducing rna (mir), is capable of promoting myofibrillogenesis and heart beating in the mutant (c/c) axolotls. the present study demonstrates that the mir gene is essential for tropomyosin (tm) expression in ax ...200919728883
mir-196 is an essential early-stage regulator of tail regeneration, upstream of key spinal cord patterning events.salamanders have the remarkable ability to regenerate many body parts following catastrophic injuries, including a fully functional spinal cord following a tail amputation. the molecular basis for how this process is so exquisitely well-regulated, assuring a faithful replication of missing structures every time, remains poorly understood. therefore a study of microrna expression and function during regeneration in the axolotl, ambystoma mexicanum, was undertaken. using microarray-based profiling ...200919682983
memory of fate and position, colorized.many of our ideas about cellular memory of fate and position come from regeneration studies in salamanders. a popular notion is that cells of the blastema transdifferentiate to different fates during limb regeneration. in a recent issue of nature, tanaka and colleagues challenge this notion. using transplant experiments with gfp-expressing axolotl, they show vividly which cells of the blastema remember their fate and position of origin.200919619486
the role of nerve signaling in limb genesis and agenesis during axolotl limb regeneration. 200919571075
cells keep a memory of their tissue origin during axolotl limb regeneration.during limb regeneration adult tissue is converted into a zone of undifferentiated progenitors called the blastema that reforms the diverse tissues of the limb. previous experiments have led to wide acceptance that limb tissues dedifferentiate to form pluripotent cells. here we have reexamined this question using an integrated gfp transgene to track the major limb tissues during limb regeneration in the salamander ambystoma mexicanum (the axolotl). surprisingly, we find that each tissue produces ...200919571878
regeneration and pattern formation - an interview with susan bryant. interviewed by richardson, michael k and chuong, cheng-ming.susan bryant is one of the leading researchers in regeneration and pattern formation. born in england in 1943, she studied biology at kings college, london (uk). after a ph.d. with angus bellairs on caudal autotomy and regeneration in lizards, she researched urodele regeneration in marcus singer's lab at case western reserve university. then, at the university of california, irvine, she adopted the axolotl as a research model for limb regeneration and pattern formation. her work supported models ...200919557688
epigenetic marks in somatic chromatin are remodelled to resemble pluripotent nuclei by amphibian oocyte extracts.reprogramming pluripotency after nuclear transplantation shows that molecules in oocytes can remodel somatic chromatin to a stem cell state. here we report on an ex-ovo system using axolotl oocyte extracts to remodel epigenetic marks of somatic chromatin. molecules present in axolotl oocyte extracts induce the reduction of the overall levels of h3k9me3, hp1alpha and dna methylation of somatic cells, and they increase the levels of h3k9ac. the levels of signal intensity detected in treated differ ...200919440040
a model of transcriptional and morphological changes during thyroid hormone-induced metamorphosis of the axolotl.anuran (frog) metamorphosis has long-served as a model of how thyroid hormones regulate post-embryonic development in vertebrates. however, comparatively little is known about urodele (salamander) metamorphosis. we conducted a detailed time-course study of induced metamorphosis in the mexican axolotl (ambystoma mexicanum) that probed metamorphic changes in morphology and gene expression in the skin. using morphometrics, quantitative pcr, histology, and in situ hybridization we demonstrate that t ...200919275901
expression of nkx2.5 in wild type, cardiac mutant, and thyroxine-induced metamorphosed hearts of the mexican axolotl.nkx2.5, a homeodomain-containing transcription factor, is known to be necessary for normal heart development in vertebrates. it is one of the earliest lineage-restricted genes expressed in cardiovascular progenitor cells and knowledge of its expression patterns has important therapeutic implications for damaged cardiomyocytes. mexican axolotl is a unique system to study heart development for two reasons: the presence of a mutant phenotype lacking organized myofibrils due to sarcomeric tropomyosi ...200919191032
cardiovascular physiology and diseases of amphibians.the class amphibia includes three orders of amphibians: the anurans (frogs and toads), urodeles (salamanders, axolotls, and newts), and caecilians. the diversity of lifestyles across these three orders has accompanying differences in the cardiovascular anatomy and physiology allowing for adaptations to aquatic or terrestrial habitats, pulmonic or gill respiration, hibernation, and body elongation (in the caecilian). this article provides a review of amphibian cardiovascular anatomy and physiolog ...200919131029
detection of mitoses in embryonic epithelia using motion field analysis.although computer simulations indicate that mitosis may be important to the mechanics of morphogenetic movements, algorithms to identify mitoses in bright field images of embryonic epithelia have not previously been available. here, the authors present an algorithm that identifies mitoses and their orientations based on the motion field between successive images. within this motion field, the algorithm seeks 'mitosis motion field prototypes' characterised by convergent motion in one direction an ...200919051076
fine structure of the epidermal leydig cells in the axolotl ambystoma mexicanum in relation to their function.the fine structure of the leydig cells in the epidermis of the strictly aquatic adult axolotl ambystoma mexicanum resembles that of similar cells in larval salamanders. the major finding of this study is that the mucous secretion of the leydig cells is released into the intercellular spaces from which it is discharged through pores onto the surface of the epidermis where it forms a mucous layer to protect the skin.20092630544
organization of positional information in the axolotl limb.we have used the phenomenon of position-dependent growth stimulation, brought about by the confrontation of cells with dissimilar positional values, to reveal the organization of positional information in the center of the upper and lower arms of axolotls. when either humerus or radius was transplanted into either dorsal or posterior positions, extra growth leading to the formation of supernumerary digits occurred following amputation through the graft. however, transplants of humerus or radius ...20092769199
evidence for a change in expression of dna ligase genes in the pleurodeles waltlii germ line during gonadogenesis.the expression of dna ligase genes was studied using the nuclear transplantation approach in the germ line of pleurodeles waltlii (p. waltlii) just before and during gonadogenesis. germ cell (gc) nuclei were isolated from larvae of p. waltlii and transplanted into unfertilized ambystoma mexicanum eggs. dna ligase activity in these eggs was then analyzed after sucrose gradient fractionation. the activity of dna ligase i (heavy form, 7.5 s) of p. waltlii was present when the transplanted gc nuclei ...20092776966
amelogenin evolution and tetrapod enamel structure.amelogenins are the major proteins involved in tooth enamel formation. in the present study, we have cloned and sequenced four novel amelogenins from three amphibian species in order to analyze similarities and differences between mammalian and non-mammalian amelogenins. the newly sequenced amphibian amelogenin sequences were from a red-eyed tree frog (litoria chloris) and a mexican axolotl (ambystoma mexicanum). we identified two amelogenin isoforms in the eastern red-backed salamander (plethod ...200919828974
acid-sensing ionic-channel functional expression in the vestibular endorgans.in the vestibular system, the electrical discharge of the afferent neurons has been found to be highly sensitive to external ph changes, and acid-sensing ionic-channels (asic) have been found to be functionally expressed in afferent neurons. no previous attempt to assay the asic function in vestibular afferent neurons has been done. in our work we studied the electrical discharge of the afferent neuron of the isolated inner ear of the axolotl (ambystoma tigrinum) to determine the participation o ...200919660522
amphibian sex determination: segregation and linkage analysis using members of the tiger salamander species complex (ambystoma mexicanum and a. t. tigrinum).little is known about the genetic basis of sex determination in vertebrates though considerable progress has been made in recent years. in this study, segregation analysis and linkage mapping were performed to localize an amphibian sex-determining locus (ambysex) in the tiger salamander (ambystoma) genome. segregation of sex phenotypes (male and female) among the second generation individuals of interspecific crosses (ambystoma mexicanum x ambystoma tigrinum tigrinum) was consistent with mendeli ...200919259115
immunofluorescent, immunogold, and electrophoretic studies for desmin in embryonic hearts of normal and cardiac mutant mexican axolotls, ambystoma mexicanum.recessive mutant gene c for "cardiac nonfunction" in axolotls results in an absence of normal heart contractions in affected embryos due to a failure of myofibril formation. in the present study, the intermediate filament protein, desmin, is compared in developing normal and mutant hearts by means of two-dimensional gel electrophoresis, immunofluorescent microscopy, and immunoelectron microscopy. tissues were fixed in periodate-lysine-paraformaldehyde or paraformaldehyde-glutaraldehyde solutions ...20092681791
microarray and cdna sequence analysis of transcription during nerve-dependent limb regeneration.microarray analysis and 454 cdna sequencing were used to investigate a centuries-old problem in regenerative biology: the basis of nerve-dependent limb regeneration in salamanders. innervated (nr) and denervated (dl) forelimbs of mexican axolotls were amputated and transcripts were sampled after 0, 5, and 14 days of regeneration.200919144100
genic regions of a large salamander genome contain long introns and novel genes.the basis of genome size variation remains an outstanding question because dna sequence data are lacking for organisms with large genomes. sixteen bac clones from the mexican axolotl (ambystoma mexicanum: c-value = 32 x 10(9) bp) were isolated and sequenced to characterize the structure of genic regions.200919144141
evidence for directional selection at a novel major histocompatibility class i marker in wild common frogs (rana temporaria) exposed to a viral pathogen (ranavirus).whilst the major histocompatibility complex (mhc) is well characterized in the anuran xenopus, this region has not previously been studied in another popular model species, the common frog (rana temporaria). nor, to date, have there been any studies of mhc in wild amphibian host-pathogen systems. we characterise an mhc class i locus in the common frog, and present primers to amplify both the whole region, and specifically the antigen binding region. as no more than two expressed haplotypes were ...200919240796
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
generation of transgenic axolotls (ambystoma mexicanum). 200920147240
axolotl (ambystoma mexicanum) in vitro fertilization. 200920147239
ambystoma mexicanum, the axolotl: a versatile amphibian model for regeneration, development, and evolution studies. 200920147230
molecular cloning and characterization of ligand- and species-specificity of amphibian estrogen receptors.estrogens are essential for normal reproductive activity in both males and females as well as for ovarian differentiation during a critical developmental stage in most vertebrates. to understand the molecular mechanisms of estrogen action and to evaluate estrogen receptor ligand interactions in amphibians, we isolated cdnas encoding the estrogen receptors (eralpha and erbeta) from the japanese firebelly newt (cynops pyrrhogaster), tokyo salamander (hynobius tokyoensis), axolotl (ambystoma mexica ...201020064516
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
[in vitro development of blastema cells in axolotl limb regeneration: effect of insulin and nerve extracts on cellular proliferation].for the purpose of investigating the nature of the nervous factor which controls cell proliferation in limb blastema of newts, we have cultured primary mesenchymous cells from limb blastemas of axolotl. the cultures were carried out in petri dishes (primaria, falcon) with a basal medium with contained diluted mem supplemented with hormones (insulin, somatotropin, hydrocortisone and thyroxine). in this medium, the cells disperse from the explant from the 4th day of culture and begin to divide fro ...20102952210
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
cellular retinoic acid binding protein: detection and quantitation in regenerating axolotl limbs.the concentrations of apo (unoccupied), holo (occupied), and total cellular retinoic acid binding protein (crabp) were measured at various stages of axolotl limb regeneration. the ratio of apo-crabp to holo-crabp declined with advancing regenerate stage until the crabp was all in the holo form. the increase in holo-crabp is correlated with a stage-dependent shift in the effect of exogenous retinoic acid on regenerate pattern, from pattern duplication to inhibition of regeneration. the data sugge ...20102838564
promotion of chromatophore differentiation in isolated premigratory neural crest cells by extracellular matrix material explanted on microcarriers.this study was undertaken to determine whether premigratory neural crest cells of the axolotl embryo differentiate autonomously into chromatophores, or whether stimuli from the environment, particularly from the extracellular matrix, are required for this process. neural crest cells were excised from the dorsal part of the premigratory crest cord and cultured alone, either in a serum-free salt solution or in the presence of fetal calf serum (fcs), and together with explants of the neural tube or ...20103081390
sciatic nerve injury model in the axolotl: functional, electrophysiological, and radiographic outcomes.the 2 aims of this study were as follows: 1) to establish outcome measures of nerve regeneration in an axolotl model of peripheral nerve injury; and 2) to define the timing and completeness of reinnervation in the axolotl following different types of sciatic nerve injury.201019764825
neurotrophic regulation of fibroblast dedifferentiation during limb skeletal regeneration in the axolotl (ambystoma mexicanum).the ability of animals to repair tissue damage is widespread and impressive. among tissues, the repair and remodeling of bone occurs during growth and in response to injury; however, loss of bone above a threshold amount is not regenerated, resulting in a "critical-size defect" (csd). the development of therapies to replace or regenerate a csd is a major focus of research in regenerative medicine and tissue engineering. adult urodeles (salamanders) are unique in their ability to regenerate compl ...201019944088
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
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
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
retinoic acid coordinately proximalizes regenerate pattern and blastema differential affinity in axolotl limbs.an assay that detects position-related differences in affinity of axolotl regeneration blastema cells in vivo was used to test whether retinoic acid, which proximalizes regenerate pattern, simultaneously proximalizes blastema cell affinity. the assay involved autografting or homografting late bud forelimb blastomas derived from the wrist, elbow or midupper arm levels to the dorsal surface of the blastema-stump junction of an ipsilateral, medium-bud-stage hindlimb regenerating from the midthigh l ...20113168786
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
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