| characterization and expression of a maternal axolotl cyclin b1 during oogenesis and early development. | the m phase promoting factor (mpf) is a dimer composed of a catalytic cdk1 subunit and a cyclin b regulatory subunit. we have characterized a cdna containing the entire coding sequence of an axolotl cyclin b1 protein that is able to promote mpf activity when added to a fraction from prophase i oocytes that contains monomeric cdk1. the axolotl cyclin b1 gene is expressed as a maternal mrna in oocytes and early embryos. its poly(a) tail length increases in metaphase ii oocytes and then decreases r ... | 2007 | 17428262 |
| modulation of the reaction cycle of the na+:ca2+, k+ exchanger. | ca(2+) concentration in retinal photoreceptor rod outer segment (os) strongly affects the generator potential kinetics and the receptor light adaptation. the response to intense light stimuli delivered in the dark produce potential changes exceeding 40 mv: since the ca(2+) extrusion in the os is entirely controlled by the na(+):ca(2+), k(+) exchanger, it is important to assess how the exchanger ion transport rate is affected by the voltage and, in general, by intracellular factors. it is indeed ... | 2007 | 17415556 |
| role of myofibril-inducing rna in cardiac tnt expression in developing mexican axolotl. | the mexican axolotl, ambystoma mexicanum, has been a useful animal model to study heart development and cardiac myofibrillogenesis. a naturally-occurring recessive mutant, gene "c", for cardiac non-function in the mexican axolotl causes a failure of myofibrillogenesis due to a lack of tropomyosin expression in homozygous mutant (c/c) embryonic hearts. myofibril-inducing rna (mir) rescues mutant hearts in vitro by promoting tropomyosin expression and myofibril formation thereafter. we have studie ... | 2007 | 17408593 |
| isolation and characterization of axolotl npdc-1 and its effects on retinoic acid receptor signaling. | retinoic acid, a key morphogen in early vertebrate development and tissue regeneration, mediates its effects through the binding of receptors that act as ligand-induced transcription factors. these binding events function to recruit an array of transcription co-regulatory proteins to specific gene promoters. one such co-regulatory protein, neuronal proliferation and differentiation control-1 (npdc-1), is broadly expressed during mammalian development and functions as an in vitro repressor of ret ... | 2007 | 17331771 |
| tropomodulin expression in developing hearts of normal and cardiac mutant mexican axolotl. | in the axolotl, ambystoma mexicanum, a simple, recessive cardiac-lethal mutation in gene "c" results in the hearts of c/c homozygous animals being deficient in sarcomeric tropomyosin (tm) and failing to form mature myofibrils. subsequently, the mutant hearts do not beat. a three-step model of myofibril assembly recently developed in cell culture prompted a reassessment of the myofibril assembly process in mutant hearts using a relatively new late marker for thin filament assembly, tropomodulin ( ... | 2006 | 17303917 |
| measurement of in vivo stress resultants in neurulation-stage amphibian embryos. | in order to obtain the first quantitative measurements of the in vivo stresses in early-stage amphibian embryos, we developed a novel instrument that uses a pair of parallel wires that are glued to the surface of an embryo normal to the direction in which the stress is to be determined. when a slit is made parallel to the wires and between them, tension in the surrounding tissue causes the slit to open. under computer control, one of the wires is moved so as to restore the original wire spacing, ... | 2007 | 17237990 |
| limb regeneration in axolotl: is it superhealing? | the ability of axolotls to regenerate their limbs is almost legendary. in fact, urodeles such as the axolotl are the only vertebrates that can regenerate multiple structures like their limbs, jaws, tail, spinal cord, and skin (the list goes on) throughout their lives. it is therefore surprising to realize, although we have known of their regenerative potential for over 200 years, how little we understand the mechanisms behind this achievement of adult tissue morphogenesis. many observations can ... | 2006 | 17205184 |
| migratory patterns and developmental potential of trunk neural crest cells in the axolotl embryo. | using cell markers and grafting, we examined the timing of migration and developmental potential of trunk neural crest cells in axolotl. no obvious differences in pathway choice were noted for dii-labeling at different lateral or medial positions of the trunk neural folds in neurulae, which contributed not only to neural crest but also to rohon-beard neurons. labeling wild-type dorsal trunks at pre- and early-migratory stages revealed that individual neural crest cells migrate away from the neur ... | 2007 | 17183528 |
| [the era of the axolotls: speculations regarding the neurobiological modifications during the adolescence]. | the article summarizes a number of recent findings about the brain changes which take place during the adolescence and the youth, their relations with their behavior and some questions are formulated with regard to the deepening of these hypothesis. | 2014 | 17146500 |
| inhibition of sonic hedgehog signaling leads to posterior digit loss in ambystoma mexicanum: parallels to natural digit reduction in urodeles. | molecular mechanisms patterning the tetrapod limb, including anterior-posterior axis determination involving sonic hedgehog (shh), have received much attention, particularly in amniotes. anterior-posterior patterning in urodele amphibians differs radically from that of amniotes in that it shows a pronounced anterior-to-posterior sequence of digit development. in contrast, amniotes develop their digits almost simultaneously with a slight posterior-to-anterior polarity. here we use cyclopamine, an ... | 2007 | 17117438 |
| wnt/beta-catenin signaling regulates vertebrate limb regeneration. | the cellular and molecular bases allowing tissue regeneration are not well understood. by performing gain- and loss-of-function experiments of specific members of the wnt pathway during appendage regeneration, we demonstrate that this pathway is not only necessary for regeneration to occur, but it is also able to promote regeneration in axolotl, xenopus, and zebrafish. furthermore, we show that changes in the spatiotemporal distribution of beta-catenin in the developing chick embryo elicit apica ... | 2006 | 17114576 |
| microarray analysis identifies keratin loci as sensitive biomarkers for thyroid hormone disruption in the salamander ambystoma mexicanum. | ambystomatid salamanders offer several advantages for endocrine disruption research, including genomic and bioinformatics resources, an accessible laboratory model (ambystoma mexicanum), and natural lineages that are broadly distributed among north american habitats. we used microarray analysis to measure the relative abundance of transcripts isolated from a. mexicanum epidermis (skin) after exogenous application of thyroid hormone (th). only one gene had a >2-fold change in transcript abundance ... | 2007 | 16926121 |
| the axolotl limb: a model for bone development, regeneration and fracture healing. | among vertebrates, urodele amphibians (e.g., axolotls) have the unique ability to perfectly regenerate complex body parts after amputation. the limb has been the most widely studied due to the presence of three defined axes and its ease of manipulation. hence, the limb has been chosen as a model to study the process of skeletogenesis during axolotl development, regeneration and to analyze this animal's ability to heal bone fractures. extensive studies have allowed researchers to gain some knowle ... | 2007 | 16920050 |
| molecular and immunohistochemical analyses of cardiac troponin t during cardiac development in the mexican axolotl, ambystoma mexicanum. | the mexican axolotl, ambystoma mexicanum, is an excellent animal model for studying heart development because it carries a naturally occurring recessive genetic mutation, designated gene c, for cardiac nonfunction. the double recessive mutants (c/c) fail to form organized myofibrils in the cardiac myoblasts resulting in hearts that fail to beat. tropomyosin expression patterns have been studied in detail and show dramatically decreased expression in the hearts of homozygous mutant embryos. becau ... | 2007 | 16888779 |
| terminal nerve-derived neuropeptide y modulates physiological responses in the olfactory epithelium of hungry axolotls (ambystoma mexicanum). | the vertebrate brain actively regulates incoming sensory information, effectively filtering input and focusing attention toward environmental stimuli that are most relevant to the animal's behavioral context or physiological state. such centrifugal modulation has been shown to play an important role in processing in the retina and cochlea, but has received relatively little attention in olfaction. the terminal nerve, a cranial nerve that extends underneath the lamina propria surrounding the olfa ... | 2006 | 16855098 |
| differential expression of tropomyosin during segmental heart development in mexican axolotl. | the mexican axolotl, ambystoma mexicanum, serves as an intriguing model to investigate myofibril organization and heart development in vertebrates. the axolotl has a homozygous recessive cardiac lethal gene "c" which causes a failure of ventricular myofibril formation and contraction. however, the conus of the heart beats, and has organized myofibrils. tropomyosin (tm), an essential component of the thin filament, has three known striated muscle isoforms (tpm1alpha, tpm1kappa, and tpm4alpha) in ... | 2006 | 16741969 |
| identification of the non-specific cytotoxic cell receptor protein 1 (nccrp1) in regenerating axolotl limbs. | the teleost non-specific cytotoxic cells (ncc) are evolutionary precursors of the mammalian natural killer (nk) cells and an important element of innate immunity. the non-specific cytotoxic cell receptor protein (nccrp1) is a characteristic cell surface protein with main functions in target cell recognition and cytotoxicity with sequence information available for many species of fish. we have isolated a cdna encoding the axolotl homologue of fish nccrp1 out of limb regeneration blastema and anal ... | 2006 | 16676190 |
| a germline gfp transgenic axolotl and its use to track cell fate: dual origin of the fin mesenchyme during development and the fate of blood cells during regeneration. | the development of transgenesis in axolotls is crucial for studying development and regeneration as it would allow for long-term cell fate tracing as well as gene expression analysis. we demonstrate here that plasmid injection into the one-cell stage axolotl embryo generates mosaic transgenic animals that display germline transmission of the transgene. the inclusion of scei meganuclease in the injections (thermes, v., grabher, c., ristoratore, f., bourrat, f., choulika, a., wittbrodt, j., joly, ... | 2006 | 16387293 |
| [myocardial regeneration in ambystoma mexicanum after surgical injury]. | ventricular resection of the heart of ambystoma mexicanum was performed and the type of tissue that restored the lesion and if it is by hypertrophy or hyperplasia of myocardium, were evaluated. masson's trichrome stain indicated that 5 days after resection, the gap was occupied with a blood clot surrounded by collagen fibres (83 +/- 6%) and muscle (10 +/- 3%) and the rest of area (7 +/- 2%) free of tissue. a proportion of 50 +/- 4 and 90 +/- 2% was muscular tissue, 10 and 30 days after injury. t ... | 2006 | 16366167 |
| the development of the hindbrain afferent projections in the axolotl: evidence for timing as a specific mechanism of afferent fiber sorting. | the aim of this study is to reveal the timing and growth pattern of central octavolateral projection development in the mexican axolotl, ambystoma mexicanum. in this amphibian species the development of the inner ear occurs first, followed by mechanosensory lateral line organs, and finally by ampullary electroreceptors. several hypotheses have been proposed about how the development of peripheral organs, including differential projections of the ear, might relate to the development of central pr ... | 2005 | 16351978 |
| myoseptal architecture of sarcopterygian fishes and salamanders with special reference to ambystoma mexicanum. | during axial undulatory swimming in fishes and salamanders muscular forces are transmitted to the vertebral axis and to the tail. one of the major components of force transmission is the myoseptal system. the structure of this system is well known in actinopterygian fishes, but has never been addressed in sarcopterygian fishes or salamanders. in this study we describe the spatial arrangement and collagen fiber architecture of myosepta in latimeria, two dipnoans, and three salamanders in order to ... | 2003 | 16351889 |
| cranial neural crest emergence and migration in the mexican axolotl (ambystoma mexicanum). | the timing and pattern of cranial neural crest cell emergence and migration in the mexican axolotl, ambystoma mexicanum, are assessed using scanning electron microscopy (sem). cranial neural crest cells emerge and begin to migrate at the time of neural fold closure and soon form three distinct streams. the most anterior (mandibular) stream emerges first, at the level of the mesencephalon. cells in this stream migrate rostroventrally around the optic vesicle. the second (hyoid) and third (branchi ... | 2002 | 16351868 |
| histamine (h3) receptors modulate the excitatory amino acid receptor response of the vestibular afferents. | although the effectiveness of histamine-related drugs in the treatment of peripheral and central vestibular disorders may be explained by their action on the vestibular nuclei, it has also been shown that antivertigo effects can take place at the peripheral level. in this work, we examined the actions of h3 histaminergic agonists and antagonists on the afferent neuron electrical discharge in the isolated inner ear of the axolotl. our results indicate that h3 antagonists such as thioperamide, clo ... | 2005 | 16310756 |
| an investigative laboratory exercise examining the cell signaling and regulatory properties of neurons in the regenerating forelimbs of the axolotl ambystoma mexicanum. | many students understand the electrical properties of neurons and can adequately describe the creation and transmission of electrical impulses. however, students often have difficulty when it comes to understanding how neurons have an equally important role in cell signaling. this latter function is crucial in the establishment of proper cell fate during regeneration. i have devised a lab that includes in its goals: 1) an investigation into the cell signaling role of neurons, 2) experience with ... | 2005 | 23493055 |
| axolotl hemoglobin: cdna-derived amino acid sequences of two alpha globins and a beta globin from an adult ambystoma mexicanum. | erythrocytes of the adult axolotl, ambystoma mexicanum, have multiple hemoglobins. we separated and purified two kinds of hemoglobin, termed major hemoglobin (hb m) and minor hemoglobin (hb m), from a five-year-old male by hydrophobic interaction column chromatography on alkyl superose. the hemoglobins have two distinct alpha type globin polypeptides (alpham and alpham) and a common beta globin polypeptide, all of which were purified in fplc on a reversed-phase column after s-pyridylethylation. ... | 2005 | 16143550 |
| automated 3-d reconstruction of the surface of live early-stage amphibian embryos. | although three-dimensional (3-d) reconstructions of the surfaces of live embyos are vital to understanding embryo development, morphogenetic tissue movements and other factors have prevented the automation of this task. here, we report an integrated set of software algorithms that overcome these challenges, making it possible to completely automate the reconstruction of embryo surfaces and other textured surfaces from multiview images. the process involves: 1) building accurate point corresponde ... | 2005 | 16119236 |
| tensile properties of embryonic epithelia measured using a novel instrument. | we present the first measurements of the tensile properties of embryonic epithelia, data that are crucial to understanding the mechanics of morphogenetic movements. fine wires were glued to the surface of an intact, live embryo using cyanoacrylate glue, after which the epithelium between the wires was separated from the remainder of the embryo by microsurgery. the wires were then separated from each other in 0.1 microm steps under computer control in order to elongate the tissue at a constant tr ... | 2005 | 16084209 |
| multiview robotic microscope reveals the in-plane kinematics of amphibian neurulation. | a new robotic microscope system, called the frogatron 3000, was developed to collect time-lapse images from arbitrary viewing angles over the surface of live embryos. embryos are mounted at the center of a horizontal, fluid-filled, cylindrical glass chamber around which a camera with special optics traverses. to hold them at the center of the chamber and revolve them about a vertical axis, the embryos are placed on the end of a small vertical glass tube that is rotated under computer control. to ... | 2005 | 16078621 |
| corticotropin-releasing hormone-mediated metamorphosis in the neotenic axolotl ambystoma mexicanum: synergistic involvement of thyroxine and corticoids on brain type ii deiodinase. | in the present study, morphological changes leading to complete metamorphosis have been induced in the neotenic axolotl ambystoma mexicanum using a submetamorphic dose of t(4) together with an injection of corticotropin-releasing hormone (crh). an injection of crh alone is ineffective in this regard presumably due to a lack of thyrotropic stimulation. using this low hormone profile for induction of metamorphosis, the deiodinating enzymes d2 and d3 known to be present in amphibians were measured ... | 2005 | 15993107 |
| hedgehog signaling controls dorsoventral patterning, blastema cell proliferation and cartilage induction during axolotl tail regeneration. | tail regeneration in urodeles requires the coordinated growth and patterning of the regenerating tissues types, including the spinal cord, cartilage and muscle. the dorsoventral (dv) orientation of the spinal cord at the amputation plane determines the dv patterning of the regenerating spinal cord as well as the patterning of surrounding tissues such as cartilage. we investigated this phenomenon on a molecular level. both the mature and regenerating axolotl spinal cord express molecular markers ... | 2005 | 15983402 |
| expression of heat-shock protein 70 during limb development and regeneration in the axolotl. | urodele amphibians (e.g., axolotls) have the unique ability, among vertebrates, to regenerate perfectly many parts of their body after amputation. the limb has been the most widely studied regenerating structure in these organisms and provides an ideal model in which to understand how vertebrates can regenerate complex tissues. the present study focuses on hsp-70, a member of the stress-related heat-shock protein family. this protein is normally induced after a stress or trauma such as heat-shoc ... | 2005 | 15965983 |
| limb chondrogenesis of the seepage salamander, desmognathus aeneus (amphibia: plethodontidae). | salamanders are infrequently mentioned in analyses of tetrapod limb formation, as their development varies considerably from that of amniotes. however, urodeles provide an opportunity to study how limb ontogeny varies with major differences in life history. here we assess limb development in desmognathus aeneus, a direct-developing salamander, and compare it to patterns seen in salamanders with larval stages (e.g., ambystoma mexicanum). both modes of development result in a limb that is morpholo ... | 2005 | 15880507 |
| anti-sense-mediated inhibition of expression of the novel striated tropomyosin isoform tpm1kappa disrupts myofibril organization in embryonic axolotl hearts. | striated muscle tropomyosin (tm) is described as containing ten exons; 1a, 2b, 3, 4, 5, 6b, 7, 8, and 9a/b. exon 9a/b has critical troponin binding domains and is found in striated muscle isoforms. we have recently discovered a smooth (exon 2a)/striated (exons 9a/b) isoform expressed in amphibian, avian, and mammalian hearts, designated as an isoform of the tpm1 gene (tpm1kappa). tpm1kappa expression was blocked in whole embryonic axolotl heart by transfection of exon-specific anti-sense oligonu ... | 2005 | 15838882 |
| cardiac myofibril formation is not affected by modification of both n- and c-termini of sarcomeric tropomyosin. | although the role of tropomyosin is well-defined in striated muscle, the precise mechanism of how tropomyosin functions is still unclear. it has been shown that extension of either n- or c-terminal ends of sarcomeric tropomyosin do not affect cardiac myofibrillogenesis, but it is not known whether simultaneous extension of both ends affects the process. for studying structural/functional relationships of sarcomeric tropomyosin, we have chosen the ambystoma mexicanum because cardiac mutant hearts ... | 2005 | 15738580 |
| isoproterenol-produced damage in amphibian heart could be mediated by adrenergic receptors located in the heart muscle. | in mammals, isoproterenol may produce heart damage in part by binding to adrenergic receptors in the coronary arteries. previously we showed evidence that isoproterenol produces cellular necrosis and interstitial fibrosis in the ventricle of the heart of an amphibian, which has no coronary arteries. the present study examines responses to 3-adrenergic receptor stimulation in the heart of urodele amphibians. the hearts from three amphibians; ambystoma mexicanum, a. tigrinum and a. dumerilii were ... | 2004 | 15633614 |
| developmental origins and evolution of jaws: new interpretation of "maxillary" and "mandibular". | cartilage of the vertebrate jaw is derived from cranial neural crest cells that migrate to the first pharyngeal arch and form a dorsal "maxillary" and a ventral "mandibular" condensation. it has been assumed that the former gives rise to palatoquadrate and the latter to meckel's (mandibular) cartilage. in anamniotes, these condensations were thought to form the framework for the bones of the adult jaw and, in amniotes, appear to prefigure the maxillary and mandibular facial prominences. here, we ... | 2004 | 15531376 |
| an introduction to the mexican axolotl (ambystoma mexicanum). | a number of unusual traits, including a remarkable capacity for wound healing and limb regeneration, make the axolotl an interesting animal model. the author provides an overview of axolotl care and use in biomedical research. | 2004 | 15457201 |
| role of cranial neural crest cells in visceral arch muscle positioning and morphogenesis in the mexican axolotl, ambystoma mexicanum. | the role of cranial neural crest cells in the formation of visceral arch musculature was investigated in the mexican axolotl, ambystoma mexicanum. dii (1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine, perchlorate) labeling and green fluorescent protein (gfp) mrna injections combined with unilateral transplantations of neural folds showed that neural crest cells contribute to the connective tissues but not the myofibers of developing visceral arch muscles in the mandibular, hyoid, and bran ... | 2004 | 15366001 |
| a critical role for thrombin in vertebrate lens regeneration. | lens regeneration in urodele amphibians such as the newt proceeds from the dorsal margin of the iris where pigment epithelial cells (pec) re-enter the cell cycle and transdifferentiate into lens. a general problem in regeneration research is to understand how the events of tissue injury or removal are coupled to the activation of plasticity in residual differentiated cells or stem cells. thrombin, a pivotal regulator of the injury response, has been implicated as a regulator of cell cycle re-ent ... | 2004 | 15293804 |
| characteristics of craniogenesis in the axolotl (ambystoma mexicanum: ambystomatidae) and the role of thyroid hormones in its regulation. | | 2017 | 15255140 |
| coupled amplification and degradation of exogenous rna injected in amphibian oocytes. | the early development of amphibians takes place in the absence of significant transcription and is controlled at the post-transcriptional level. we have reported that in vitro synthesized transcripts injected into axolotl fertilized eggs or oocytes were not continuously degraded as their abundance apparently fluctuated over time, with detected amounts sometimes higher than initial injected amounts. to further characterize this phenomenon, we have co-injected rna chain terminators to prevent rna ... | 2004 | 15161959 |
| low submetamorphic doses of dexamethasone and thyroxine induce complete metamorphosis in the axolotl (ambystoma mexicanum) when injected together. | entanglement of functions between the adrenal (or interrenal) and thyroid axis has been well described for all vertebrates and can be tracked down up to the level of gene expression. both thyroid hormones and corticosteroids may induce morphological changes leading to metamorphosis climax in the neotenic mexican axolotl (ambystoma mexicanum). in a first series of experiments, metamorphosis was induced with an injection of 25 microg t(4) on three alternate days as judged by a decrease in body wei ... | 2004 | 15158126 |
| early expression of two tdt isoforms in the hematopoietic system of the mexican axolotl. implications for the evolutionary origin of the n-nucleotide addition. | nontemplate (n)-nucleotide addition by the terminal dideoxynucleotidyl transferase (tdt) at the junctions of rearranging v( d) j gene segments greatly contribute to antigen-receptor diversity. tdt has been identified in several vertebrate species, where it is highly conserved. we report here the isolation of two forms of tdt mrna in an amphibian, the mexican axolotl. the isoform tdt1 shares all of the conserved structural motifs required for tdt activity and displays an average of 50-58% similar ... | 2004 | 15146297 |
| ultrastructure of the external gill epithelium of the axolotl, ambystoma mexicanum with reference to ionic transport. | the ultrastructure of the external gill epithelium of the axolotl, ambystoma mexicanum, has been examined using conventional transmission electron microscopy to elucidate its role in ionic transport. four cell types are identified in the gill filament and primary gill bar epithelium. these are granular, ciliated, leydig and basal cells. a fifth cell type, the flat mitochondria-rich cell is only found in the gill bar epithelium. the predominant granular cells display microvilli at their surface a ... | 2003 | 15137686 |
| the epithelia of the protrusible tongue of eurycea longicauda guttolineata (hoolbrook 1838) (urodela: plethodontidae). | in this study the lingual and sublingual glands, the lingual stem and the epithelial surface of the protrusible secondary tongue were investigated by light, scanning and transmission electron microscopy. the quality of the secretions of the epithelia was characterized histochemically. the lingual epithelium is formed by superficial (pavement) and goblet cells and at the margin of the tongue pad are also regions covered by ciliated cells. on the dorsal part of the tongue there are goblet cells of ... | 2003 | 15121544 |
| discrimination of conspecific sex and reproductive condition using chemical cues in axolotls ( ambystoma mexicanum). | chemosensory cues play an important role in the daily lives of salamanders, mediating foraging, conspecific recognition, and territorial advertising. we investigated the behavioral effects of conspecific whole-body odorants in axolotls, ambystoma mexicanum, a salamander species that is fully aquatic. we found that males increased general activity when exposed to female odorants, but that activity levels in females were not affected by conspecific odorants. although males showed no difference in ... | 2004 | 15034733 |
| activation of cdc2 kinase during meiotic maturation of axolotl oocyte. | activity of cdc2, the universal inducer of mitosis, is regulated by phosphorylation and binding to cyclin b. comparative studies using oocytes from several amphibian species have shown that different mechanisms allow cdc2 activation and entry into first meiotic division. in xenopus, immature oocytes stockpile pre-m-phase promoting factor (mpf) composed of cdc2-cyclin b complexes maintained inactive by thr14 and tyr15 phosphorylation of cdc2. activation of mpf relies on the conversion of pre-mpf ... | 2004 | 15013793 |
| retinoic acid repatterns axolotl lateral line receptors. | the effects of all-trans retinoic acid on the development of the lateral line placodes of axolotls was studied. late gastrula and early neurula were exposed to 10(-7) to 10(-5) m retinoic acid for one hour and then reared until they would normally be feeding larvae. as in other vertebrates, the extent of the developmental abnormalities is concentration dependent. those embryos exposed to the highest concentration of retinoic acid failed to form much of the forebrain and midbrain, including the o ... | 2004 | 15005576 |
| [specific growth rate and the rate of energy metabolism in the ontogenesis of axolotl, ambystoma mexicanum (amphibia: ambystomatidae)]. | concordant changes in the rate of energy metabolism and specific growth rate of axolotls have been revealed. several periods of ontogeny are distinguished, which differ in the ratio of energy metabolism to body weight and, therefore, are described by different allometric equations. it is suggested that the specific growth rate of an animal determines the type of dependence of energy metabolism on body weight. | 2016 | 14994475 |
| combined intrinsic and extrinsic influences pattern cranial neural crest migration and pharyngeal arch morphogenesis in axolotl. | cranial neural crest cells migrate in a precisely segmented manner to form cranial ganglia, facial skeleton and other derivatives. here, we investigate the mechanisms underlying this patterning in the axolotl embryo using a combination of tissue culture, molecular markers, scanning electron microscopy and vital dye analysis. in vitro experiments reveal an intrinsic component to segmental migration; neural crest cells from the hindbrain segregate into distinct streams even in the absence of neigh ... | 2004 | 14738875 |
| downregulation of n1 gene expression inhibits the initial heartbeating and heart development in axolotls. | recessive mutant gene c in the axolotl results in a failure of affected embryos to develop contracting hearts. this abnormality can be corrected by treating the mutant heart with rna isolated from normal anterior endoderm or from endoderm conditioned medium. a cdna library was constructed from the total conditioned medium rna using a random priming technique in a pcdnaii vector. we have previously identified a clone (designated as n1) from the constructed axolotl cdna library, which has a unique ... | 2004 | 14729455 |
| endogenous electric fields in embryos during development, regeneration and wound healing. | all embryos that have been investigated drive ionic currents through themselves and these currents will generate internal electric fields. here, those examples in which such fields have been measured directly are discussed. the first such measurements were made in chick embryos and about 20 mv mm(-1) was measured near the posterior intestinal portal in 2-4 day-old embryos. this electric field is important for the development of tail structures because reducing its magnitude results in abnormal t ... | 2003 | 14690282 |
| gustatory neurons derived from epibranchial placodes are attracted to, and trophically supported by, taste bud-bearing endoderm in vitro. | taste buds are multicellular receptor organs innervated by the viith, ixth, and xth cranial nerves. in most vertebrates, taste buds differentiate after nerve fibers have reached the lingual epithelium, suggesting that nerves induce taste buds. however, under experimental conditions, taste buds of amphibians develop independently of innervation. thus, rather than being induced by nerves, the developing taste periphery likely regulates ingrowing nerve fibers. to test this idea, we devised a cultur ... | 2003 | 14651931 |
| axolotl pronephric duct migration requires an epidermally derived, laminin 1-containing extracellular matrix and the integrin receptor alpha6beta1. | the epidermis overlying the migrating axolotl pronephric duct is known to participate in duct guidance. this epidermis deposits an extracellular matrix onto the migrating duct and its pathway that is a potential source of directional guidance cues. the role of this matrix in pronephric duct guidance was assayed by presenting matrix deposited on microcarriers directly to migrating pronephric ducts in situ. we found that reorientation of extracellular-matrix-bearing carriers prior to their present ... | 2003 | 14522870 |
| characterization of glycosaminoglycans during tooth development and mineralization in the axolotl, ambystoma mexicanum. | glycosaminoglycans (gags) involved in the formation of the teeth of ambystoma mexicanum were located and characterized with the cuprolinic blue (cb) staining method and transmission electron microscopy (tem). glycosaminoglycan-cuprolinic blue precipitates (gagcb) were found in different compartments of the mineralizing tissue. various populations of elongated gagcb could be discriminated both according to their size and their preferential distribution in the extracellular matrix (ecm). gagcb pop ... | 2003 | 14517102 |
| tooth development in ambystoma mexicanum: phosphatase activities, calcium accumulation and cell proliferation in the tooth-forming tissues. | prerequisites of tooth formation, cell proliferation in the tooth-forming tissues, calcium accumulation and the enzymatic activities of alkaline (alp) and acid phosphatases (acp) were investigated by immunohistochemical and histochemical methods in various developmental stages of the mexican axolotl, ambystoma mexicanum. during the growth of replacement teeth, the tooth-forming tissues continually recruit cells from the surrounding regions. the basal layer of the oral epithelium, the dental lami ... | 2003 | 12801088 |
| olfactory signal modulation by molluscan cardioexcitatory tetrapeptide (fmrfamide) in axolotls (ambystoma mexicanum). | the terminal nerve, which innervates the nasal epithelia of most jawed vertebrates, is believed to release neuropeptides that modulate activity of sensory receptor neurons. the terminal nerve usually contains gonadotropin-releasing hormone as well as at least one other peptide that has not been characterized, but which bears some structural similarity to molluscan cardioexcitatory tetrapeptide (fmrfamide) and neuropeptide tyrosine (npy). we investigated the effects of fmrfamide on both voltage-g ... | 2003 | 12771020 |
| relationship between cardiac protein tyrosine phosphorylation and myofibrillogenesis during axolotl heart development. | the axolotl, ambystoma mexicanum, is a useful system for studying embryogenesis and cardiogenesis. to understand the role of protein tyrosine phosphorylation during heart development in normal and cardiac mutant axolotl embryonic hearts, we have investigated the state of protein tyrosine residues (phosphotyrosine, p-tyr) and the relationship between p-tyr and the development of organized sarcomeric myofibrils by using confocal microscopy, two-dimensional isoelectric focusing (ief)/sds-polyacryla ... | 2003 | 12747935 |
| selective activation of thrombin is a critical determinant for vertebrate lens regeneration. | the regeneration of structures in adult animals depends on a mechanism for coupling the acute response to tissue injury or removal with the local activation of plasticity in residual differentiated cells or stem cells. many potentially relevant signals are generated after injury, and the nature of this mechanism has not been elucidated for any instance of regeneration. lens regeneration in adult vertebrates always occurs at the pupillary margin of the dorsal iris, where pigmented epithelial cell ... | 2003 | 12747839 |
| a point mutation in bioactive rna results in the failure of mutant heart correction in mexican axolotls. | ambystoma mexicanum is an intriguing animal model for studying heart development because it carries a mutation in gene c. hearts of homozygous recessive (c/c) mutant embryos do not contain organized myofibrils and fail to beat. the defect can be corrected by organ-culturing the mutant heart in the presence of rna from anterior endoderm or endoderm/mesoderm-conditioned medium. by screening a cdna library made of total conditioned medium rna from normal axolotl embryonic endoderm, we isolated a si ... | 2003 | 12721841 |
| neural crest contributions to the lamprey head. | the neural crest is a vertebrate-specific cell population that contributes to the facial skeleton and other derivatives. we have performed focal dii injection into the cranial neural tube of the developing lamprey in order to follow the migratory pathways of discrete groups of cells from origin to destination and to compare neural crest migratory pathways in a basal vertebrate to those of gnathostomes. the results show that the general pathways of cranial neural crest migration are conserved thr ... | 2003 | 12702647 |
| gonadotropin releasing hormone (gnrh) modulates odorant responses in the peripheral olfactory system of axolotls. | peripheral signal modulation plays an important role in sensory processing. activity in the vertebrate olfactory epithelium may be modulated by peptides released from the terminal nerve, such as gonadotropin releasing hormone (gnrh). here, we demonstrate that gnrh modulates odorant responses in aquatic salamanders (axolotls, ambystoma mexicanum). we recorded electrical field potentials (electro-olfactograms, or eogs) in response to stimulation with four different amino acid odorants, l-lysine, l ... | 2003 | 12672784 |
| surface glycoconjugates in the olfactory system of ambystoma mexicanum. | lectin binding histochemistry was performed on the olfactory system of neotenic and metamorphosed ambystoma mexicanum to investigate the distribution and density of defined carbohydrate residues on the cell surface glycoproteins of the olfactory and vomeronasal receptor cells and their terminals in the olfactory bulbs. the lectin binding patterns indicate that the main olfactory system possesses a high density of n-acetyl-galactosamine and n-acetyl-glucosamine residues, while the vomeronasal sys ... | 2003 | 12655612 |
| ontogeny of the vip system in the gastro-intestinal tract of the axolotl, ambystoma mexicanum: successive appearance of co-existing pacap and nos. | evidence for the presence and potential co-existence of vasoactive intestinal polypeptide (vip), pituitary adenylate cyclase-activating polypeptide (pacap) and nitric oxide synthase (nos) in gastro-intestinal endocrine cells and/or nerve fibers is conflicting and very few results exist on development. this immunofluorescence study aims to clarify the appearance and localization of vip, pacap and nos in the gastro-intestinal tract of the axolotl, ambystoma mexicanum, during ontogeny. vip-immunore ... | 2003 | 12649730 |
| extending the table of stages of normal development of the axolotl: limb development. | the existing table of stages of the normal development of the axolotl (ambystoma mexicanum) ends just after hatching. at this time, the forelimbs are small buds. in this study, we extend the staging series through completion of development of the forelimbs and hindlimbs. | 2003 | 12619140 |
| expression of complement 3 and complement 5 in newt limb and lens regeneration. | some urodele amphibians possess the capacity to regenerate their body parts, including the limbs and the lens of the eye. the molecular pathway(s) involved in urodele regeneration are largely unknown. we have previously suggested that complement may participate in limb regeneration in axolotls. to further define its role in the regenerative process, we have examined the pattern of distribution and spatiotemporal expression of two key components, c3 and c5, during limb and lens regeneration in th ... | 2003 | 12594255 |
| electroporation as a tool to study in vivo spinal cord regeneration. | tailed amphibians such as axolotls and newts have the unique ability to fully regenerate a functional spinal cord throughout life. where the cells come from and how they form the new structure is still poorly understood. here, we describe the development of a technique that allows the visualization of cells in the living animal during spinal cord regeneration. a microelectrode needle is inserted into the lumen of the spinal cord and short rapid pulses are applied to transfer the plasmids encodin ... | 2003 | 12557220 |
| excretory nitrogen metabolism in the juvenile axolotl ambystoma mexicanum: differences in aquatic and terrestrial environments. | the fully grown but nonmetamorphosed (juvenile) axolotl ambystoma mexicanum was ureogenic and primarily ureotelic in water. a complete ornithine-urea cycle (ouc) was present in the liver. aerial exposure impeded urea (but not ammonia) excretion, leading to a decrease in the percentage of nitrogen excreted as urea in the first 24 h. however, urea and not ammonia accumulated in the muscle, liver, and plasma during aerial exposure. by 48 h, the rate of urea excretion recovered fully, probably due t ... | 2013 | 12529847 |
| ectoderm to mesoderm lineage switching during axolotl tail regeneration. | foreign environments may induce adult stem cells to switch lineages and populate multiple tissue types, but whether this mechanism is used for tissue repair remains uncertain. urodele amphibians can regenerate fully functional, multitissue structures including the limb and tail. to determine whether lineage switching is an integral feature of this regeneration, we followed individual spinal cord cells live during tail regeneration in the axolotl. spinal cord cells frequently migrate into surroun ... | 2002 | 12471259 |
| amphioxus and lamprey ap-2 genes: implications for neural crest evolution and migration patterns. | the neural crest is a uniquely vertebrate cell type present in the most basal vertebrates, but not in cephalochordates. we have studied differences in regulation of the neural crest marker ap-2 across two evolutionary transitions: invertebrate to vertebrate, and agnathan to gnathostome. isolation and comparison of amphioxus, lamprey and axolotl ap-2 reveals its extensive expansion in the vertebrate dorsal neural tube and pharyngeal arches, implying co-option of ap-2 genes by neural crest cells e ... | 2002 | 12397104 |
| immunocytochemical localization of keratins, associated proteins and uptake of histidine in the epidermis of fish and amphibians. | keratinization and the role of histidine in some species of fish and amphibians have been analyzed by immunocytochemistry and autoradiography. in cartilaginous and bony fishes, staining of acidic (ae1-positive) and basic (ae3-positive) keratins was strong and their distribution patterns were uniform in all epidermal layers. the ae2 antibody (for keratins k1 and k10 that are typical for keratinization) did not produce any positivity. this was also observed in lungfish epidermis but the ae2 antibo ... | 2002 | 12389745 |
| effects of dexamethasone treatment on iodothyronine deiodinase activities and on metamorphosis-related morphological changes in the axolotl (ambystoma mexicanum). | in amphibians, there is a close interaction between the interrenal and the thyroidal axes. hypothalamic corticotropin-releasing hormone or related peptides stimulate thyroidal activity by increasing thyrotropin synthesis and release, while corticosterone accelerates both spontaneous and thyroid hormone-induced metamorphosis. one of the mechanisms that is thought to contribute to this acceleration is a corticosterone-induced change in peripheral deiodinating activity. the present experiments were ... | 2002 | 12383443 |
| different regulation of t-box genes tbx4 and tbx5 during limb development and limb regeneration. | the t-domain transcription factors tbx4 and tbx5 have been implicated, by virtue of their limb-type specific expression, in controlling the identity of vertebrate legs and arms, respectively. to study the roles of these genes in developing and regenerating limbs, we cloned tbx4 and tbx5 cdnas from the newt, and generated antisera that recognize tbx4 or tbx5 proteins. we show here that, in two urodele amphibians, newts and axolotls, the regulation of tbx4 and tbx5 differs from higher vertebrates. ... | 2002 | 12376111 |
| differential post-transcriptional regulations of wnt mrnas upon axolotl meiotic maturation. | the products of the wntgene family play an essential role in several aspects of embryo patterning. we have investigated the post-transcriptional regulation of three of these genes: awnt-1, awnt-5a and awnt-5b during axolotl (ambystoma mexicanum) oogenesis, oocyte maturation and early development. we show that awnt-1, awnt-5a and awnt-5b mrnas are maternally expressed. the three transcripts are tightly regulated at specific times and display differential mrna stability, poly(a) tail length and lo ... | 2002 | 12216985 |
| expression of hoxa5 in the heart is upregulated during thyroxin-induced metamorphosis of the mexican axolotl (ambystoma mexicanum). | widespread external and internal changes in body morphology have long been known to be hallmarks of the process of metamorphosis. however, more subtle changes, particularly at the molecular level, are only now beginning to be understood. a number of transcription factors have recently been shown to alter expression either in levels of message or in isoforms expressed. in this article, we describe a dramatic increase in the expression of the homeobox gene hoxa5 in the heart and aorta of the mexic ... | 2001 | 12213975 |
| gallium nitrate: effects on cartilage during limb regeneration in the axolotl, ambystoma mexicanum. | gallium nitrate, a drug shown to have efficacy in paget's disease of bone, hypercalcemia of malignancy, and a variety of experimental autoimmune diseases, also inhibits the growth of some types of cancer. we examined dose and timing of administration of gallium nitrate on limb regeneration in the mexican axolotl, ambystoma mexicanum. administered by intraperitoneal injection, gallium nitrate inhibited limb regeneration in a dose-dependent manner. gallium nitrate initially suppressed epithelial w ... | 2002 | 12210121 |
| identification and expression of helios, a member of the ikaros family, in the mexican axolotl: implications for the embryonic origin of lymphocyte progenitors. | transcription factors of the ikaros gene family are critical for the differentiation of t and b lymphocytes from pluripotent hematopoietic stem cells. to study the first steps of lymphopoiesis in the mexican axolotl, we have cloned the helios ortholog in this urodele amphibian species. we demonstrated that the axolotl helios contains a 144-bp deletion at the 5' end of the activation domain. helios is expressed in both the thymus and spleen but not in the liver of the pre-adult axolotl. during on ... | 2002 | 12115658 |
| intraperitoneal protein injection in the axolotl: the amphibian kidney as a novel model to study tubulointerstitial activation. | a substantial body of experimental evidence suggests that protein loading causes activation of proximal tubular epithelial cells with consecutive interstitial fibrosis. these studies have mostly been performed using mammalian in vivo models of glomerular damage or tissue cultures of mammalian tubulointerstitial cells. the kidney of the axolotl contains not only closed nephrons, but also nephrons with ciliated peritoneal funnels called nephrostomes that have access to the peritoneal fluid. inject ... | 2002 | 12081563 |
| development of larval and transformed teeth in ambystoma mexicanum (urodela, amphibia): an ultrastructural study. | odontogenesis of early larval non-pedicellate teeth, late larval teeth with a more or less distinct dividing zone and fully transformed pedicellate teeth in ambystoma mexicanum (urodela) was studied to obtain insights into the development of differently structured teeth in lower vertebrates. using transmission electron microscopy we investigated five developmental stages: (1) papilla; (2) bell stage (secretion of the matrix begins); (3) primordium (mineralization and activity of ameloblasts star ... | 2002 | 11989966 |
| structure, diversity and expression of the tcrdelta chains in the mexican axolotl. | mammals and birds have two major populations of t cells, based on the molecular composition and biological properties of their antigen receptors (tcr). alpha beta t cells recognize antigenic peptides linked to major histocompatibility complex (mhc) molecules, and gamma delta t cells recognize native peptide or non-peptide antigens independently of mhc. very little is known about gamma delta t cells in ectothermic vertebrates. we have cloned and characterized the tcrdelta chains of an urodele amp ... | 2002 | 11981822 |
| characterization of a tm-4 type tropomyosin that is essential for myofibrillogenesis and contractile activity in embryonic hearts of the mexican axolotl. | a striated muscle isoform of a tropomyosin (tm-4) gene was characterized and found to be necessary for contractile function in embryonic heart. the full-length clone of this isoform was isolated from the mexican axolotl (ambystoma mexicanum) and named axolotl tropomyosin cardiac-3 (atmc-3). the gene encoded a cardiac-specific tropomyosin protein with 284 amino acid residues that demonstrated high homology to the xenopus cardiac tm-4 type tropomyosin. northern blot analysis indicates a transcript ... | 2002 | 11968015 |
| electrorotation of axolotl embryos. | the frequency dependent dielectric properties of individual axolotl embryos (ambystoma mexicanum) were investigated experimentally utilizing the technique of electrorotation. individual axolotl embryos, immersed in low conductivity media, were subjected to a known frequency and fixed amplitude rotating ac electric field and the ensuing rotational motion of the embryo was monitored using a conventional optical microscope. none of the embryos in the pregastrulation or neurulation stages of develop ... | 2002 | 11891751 |
| retinoid antagonists inhibit normal patterning during limb regeneration in the axolotl, ambystoma mexicanum. | retinoic acid (ra) has been detected in the regenerating limb of the axolotl, and exogenous ra can proximalize, posteriorize, and ventralize blastemal cells. thus, ra may be an endogenous regulatory factor during limb regeneration. we have investigated whether endogenous retinoids are essential for patterning during axolotl (ambystoma mexicanum) limb regeneration by using retinoid antagonists that bind to specific rar (retinoic acid receptor) or rxr (retinoid x receptor) retinoid receptor subtyp ... | 2002 | 11857478 |
| relationships between neuronal cell adhesion molecule and lhrh neurons in the urodele brain: a developmental immunohistochemical study. | polysialic acid (psa), a homopolymer attached to neural cell adhesion molecule (ncam) is considered a major hallmark of vertebrate cell migration. we studied the distribution of psa-ncam by immunohistochemistry, during brain development, in two urodele amphibians, pleurodeles waltl and the neotenic newt ambystoma mexicanum. in both species a gradual increase of immunolabelling was observed throughout the brain from developmental stage 30 to stage 52. at the onset of metamorphosis, some differenc ... | 2001 | 11759809 |
| specification of pharyngeal endoderm is dependent on early signals from axial mesoderm. | the development of taste buds is an autonomous property of the pharyngeal endoderm, and this inherent capacity is acquired by the time gastrulation is complete. these results are surprising, given the general view that taste bud development is nerve dependent, and occurs at the end of embryogenesis. the pharyngeal endoderm sits at the dorsal lip of the blastopore at the onset of gastrulation, and because this taste bud-bearing endoderm is specified to make taste buds by the end of gastrulation, ... | 2001 | 11714682 |
| expression of axwnt-8 and axszl in the urodele, axolotl: comparison with xenopus. | in both the urodele axolotl and the anuran xenopus, wnt-8 is expressed in posterior lateral plate mesoderm (lpm) in neurula and tailbud stages. in contrast to xenopus, expression in axolotl is more prominent in gastrula endoderm, is not initiated in mesoderm until late gastrulation, and is present in the tailbud and in the brain at tailbud stages. sizzled is expressed in axolotl in the ventral region, similar to its pattern in xenopus. in axolotl, the wnt-8-expressing lpm remains relatively dors ... | 2001 | 11702200 |
| histochemical and immunohistochemical localization of neuronal nitric oxide synthase in the olfactory epithelium of the axolotl, ambystoma mexicanum. | the aim of this study was to describe the anatomic distribution of neuronal nitric oxide synthase immunoreactivity (nnos-ir) and nicotinamide-adenine dinucleotide phosphate-diaphorase (nadph-d) staining in the olfactory epithelium of the axolotl, juvenile, and neotenic adult, ambystoma mexicanum. nitric oxide (no, nitrogen monoxide) is a widespread molecule that has been identified both as a neuromodulator and as an intracellular messenger. in the olfactory system, no has been proposed to play a ... | 2001 | 11485369 |
| redneck, a new mutant of the axolotl (ambystoma mexicanum) likely affects the development of cranial neural crest. | a novel developmental mutant in the mexican axolotl is described. designated redneck (rn), the mutant gene is inherited as a simple mendelian recessive. in homozygotes, rn causes massive haemorrhage in the posterior head, rostrocaudal compression of the craniovisceral skeleton, abnormal differentiation of vertebral cartilage, micrognathia, aglossia, microphthalmia and abnormal hepatic development. affected larvae become evident at the onset of feeding, and eventually die of starvation. based on ... | 2001 | 11461006 |
| the eyeless mutant gene (e) in the mexican axolotl (ambystoma mexicanum) affects pax-6 expression and forebrain axonogenesis. | this study tested the hypothesis that changes in the patterns of pax-6 expression disrupt the anatomy and axonogenesis of the diencephalic areas of the eyeless axolotl. proper pax-6 expression is necessary for eye and hypothalamus morphogenesis. since the expression boundaries of pax-6 also provide a permissive environment for axonal outgrowth, an extensive study examining the effects of the eyeless gene (e) in the mexican axolotl upon pax-6 expression and forebrain axonogenesis was begun. this ... | 2001 | 11461001 |
| in vivo imaging indicates muscle fiber dedifferentiation is a major contributor to the regenerating tail blastema. | during tail regeneration in urodele amphibians such as axolotls, all of the tissue types, including muscle, dermis, spinal cord, and cartilage, are regenerated. it is not known how this diversity of cell types is reformed with such precision. in particular, the number and variety of mature cell types in the remaining stump that contribute to the blastema is unclear. using nomarski imaging, we followed the process of regeneration in the larval axolotl tail. combining this with in vivo fluorescent ... | 2001 | 11456451 |
| creation of chimeric mutant axolotls: a model to study early embryonic heart development in mexican axolotls. | the mexican axolotl (ambystoma mexicanum) provides an excellent model for studying heart development since it carries a cardiac lethal mutation in gene c that results in failure of contraction of mutant embryonic myocardium. in cardiac mutant axolotls (c/c) the hearts do not beat, apparently because of an absence of organized myofibrils. to date, there has been no way to analyze the genotypes of embryos from heterozygous spawnings (+/c x +/c) until stage 35 when the normal (+/c or +/+) embryos f ... | 2001 | 11411308 |
| lateral line placodes are induced during neurulation in the axolotl. | in order to determine the time window for induction of lateral line placodes in the axolotl, we performed two series of heterotopic and isochronic transplantations from pigmented to albino embryos at different stages of embryogenesis and assessed the distribution of pigmented neuromasts in the hosts at later stages. first, ectoderm from the prospective placodal region was transplanted to the belly between early neurula and mid tailbud stages (stages 13-27). whereas grafts from early neurulae typ ... | 2001 | 11356019 |
| complexity of the t cell receptor cbeta isotypes in the mexican axolotl: structure and diversity of the vdjcbeta3 and vdjcbeta4 chains. | we have reported previously the presence of two t cell receptor beta-chain constant region (cbeta) isotypes in the mexican axolotl. specific dbeta and jbeta segments were present at the vbeta-cbeta1 and vbeta-cbeta2 junctions and nine vbeta families which associate with both isotypes were characterized. this report describes two new cbeta isotypes, cbeta3 and cbeta4. about 70 % of the amino acids in cbeta3 are identical to cbeta1 and cbeta2. a dbeta3 and a single jbeta3 were found at the vbeta-c ... | 2001 | 11180104 |
| development and regulation of response properties in spinal cord motoneurons. | the intrinsic response properties of spinal motoneurons determine how converging premotor neuronal input is translated into the final motor command transmitted to muscles. from the patchy data available it seems that these properties and their underlying currents are highly conserved in terrestrial vertebrates in terms of both phylogeny and ontogeny. spinal motoneurons in adults are remarkably similar in many respects ranging from the resting membrane potential to pacemaker properties. apart fro ... | 2000 | 11165788 |
| distribution and innervation of taste buds in the axolotl. | adult axolotls have approximately 1,400 taste buds in the epithelium of the pharyngeal roof and floor and the medial surfaces of the visceral bars. these receptors are most dense on the lingual surfaces of the upper and lower jaws, slightly less dense throughout lateral portions of the pharyngeal roof and floor, and more sparse within medial portions of the pharyngeal roof and floor, except for a median oval patch of receptors located rostrally between the vomerine tooth fields. each taste bud i ... | 2000 | 11124515 |
| immunohistochemical demonstration of hyaluronan and its possible involvement in axolotl neural crest cell migration. | hyaluronan (ha), an extracellular matrix component, is involved mainly in the control of cell proliferation, neural crest and tumor cell migration, and wound repair. we investigated the effect of hyaluronan on neural crest (nc) cell migration and its ultrastructural localization in dark (wild-type) and white mutant embryos of the mexican axolotl (ambystoma mexicanum, amphibia). the axolotl system is an accepted model for studying mechanisms of nc cell migration. using a biotinylated hyaluronan b ... | 2000 | 11121304 |
| gdnf and gfralpha-1 are components of the axolotl pronephric duct guidance system. | in mammals, secretion of gdnf by the metanephrogenic mesenchyme is essential for branching morphogenesis of the ureteric bud and, thus, metanephric development. however, the expression pattern of gdnf and its receptor complex-the gpi-linked ligand-binding protein, gfralpha-1, and the ret tyrosine kinase signaling protein-indicates that it could operate at early steps in kidney development as well. furthermore, the developing nephric systems of fish and amphibian embryos express components of the ... | 2000 | 11087631 |
| the odontoclasts of ambystoma mexicanum. | the resorption of teeth in ambystoma mexicanum during postembryonal ontogenesis and induced metamorphosis occurs by means of light-microscopic detectable giant-cells. these have morphological and functional characters similar to those of odontoclasts of other vertebrates. the multinucleated odontoclasts resorb not only the pedicel (base), but the stalk of the tooth, too. when active, the cells form a ruffled border and a sealing zone. in this way they are able to demineralize the hard tissues of ... | 2000 | 11035635 |
| expression of the cardiac actin gene in axolotl embryos. | axolotis are an important model system for studying heart development. patterning of the somitic mesoderm occurs in axolotis in a manner that is much more similar to the pattern observed in higher vertebrates than in xenopus. for these reasons we cloned the axolotl cardiac actin gene, since this gene is expressed during the development of both somitic and cardiac muscle in other vertebrates. in this paper we characterize its expression. expression of cardiac actin rna is switched on during gastr ... | 2000 | 11032182 |
| matrix metalloproteinase production in regenerating axolotl spinal cord. | in urodele amphibian spinal cord regeneration, the ependymal cells lining the central canal remodel the lesion site to favor axonal regrowth. we profiled the production of matrix metalloproteinases by injury-reactive mesenchymal ependymal cells in vivo and in vitro and found that matrix metalloproteinases are involved in this remodeling process in the axolotl (ambystoma mexicanum). the production of cell-associated matrix metalloproteinases in vivo was shown to be identical to that in our cultur ... | 2006 | 11013020 |