Publications

epicardial development in the axolotl, ambystoma mexicanum.	recent studies on avian and mammalian embryos have established that the epicardium is derived, not from the early heart tube, but from mesothelial tissue overlying the sinus venosus. we tested the validity of this concept for amphibia by examining normal and cardiac lethal (c/c) mutant axolotl embryos (stages 35-43) by electron microscopy. in axolotl embryos, the myocardial surface of the heart remains exposed to the pericardial fluid through stage 39. at this stage the transverse septum release ...	1990	2301739
developmentally regulated lectin in dark versus white axolotl embryos.	the white mutant of the mexican axolotl, a. mexicanum, involves an ectodermal defect which prevents melanophore colonization. endogenous lectins have been suggested to function in neural crest-derived melanophore adhesion in other animals. to determine if differences in endogenous lectins exist in dark and white axolotls during melanophore colonization, white and dark ectoderm and carcass tissues have been assayed for lectin activity at premigratory, early migratory, and late migratory neural cr ...	1990	2302235
regeneration in vitro of axolotl peripheral and central axons.	peripheral nerves and spinal cords of axolotls were maintained in organ culture for periods of up to 2 weeks. sensory axons in peripheral nerves and the dorsal funiculus of the spinal cord showed regeneration through the crush site within about 2 days. axonal regeneration also occurred in peripheral nerves after cutting but was dependent on close contact between proximal and distal stumps of nerve. when cells in the distal stump of nerve were killed by freezing, axonal regeneration was inhibited ...	1990	21551566
the development of the larval pigment patterns in triturus alpestris and ambystoma mexicanum.	1. melanophores and xanthophores are pigment cell derivatives of the nc. in amphibian embryos they migrate from their original position on the neural tube dorsally (into the dorsal fin) as well as laterally (between somites and epidermis) and arrange themselves into typical pigment patterns of the skin. we investigated pigment pattern formation in two species of tailed amphibians, triturus alpestris (alpine newt) and ambystoma mexicanum (mexican axolotl). in larvae of t. alpestris alternating lo ...	1990	2368640
development of the mechanoreceptive lateral-line system in the axolotl: placode specification, guidance of migration, and the origin of neuromast polarity.	the mechanosensory lateral-line system offers a unique opportunity to study a wide variety of developmental phenomena, including cell migration, the origin of polarity, and pattern formation. in this study, we use a series of transplantation experiments to examine some of the factors affecting the origin of the lateral-line placodes, the establishment of sensory organ polarity and placement, and the guidance of cell migration in the mexican axolotl (ambystoma mexicanum). we find that placode-for ...	1990	2244689
[v. laufberger on metamorphosis in the axolotl].		1990	2225132
large disulfide-stabilized proteoglycan complexes are synthesized by the epidermis of axolotl embryos.	proteoglycans (pgs) synthesized by the epidermis during stages crucial to the subepidermal migration of neural crest cells in the trunk of the axolotl (ambystoma mexicanum, urodela, amphibia) embryo were studied. the glycosaminoglycan chains were biosynthetically labeled with [35s]sulfate in vitro during a period corresponding to the onset of migration. after extraction with guanidine hcl, the radiolabeled pgs were separated according to size by molecular-sieve chromatography on sepharose cl-2b ...	1991	1929407
effect of precocious and delayed afferent arrival on synapse localization on the amphibian mauthner cell.	afferents often form synapses on restricted regions of their target cells. the connections between vestibular axons and the mauthner cell are an example of this sort of specificity. the mauthner cells are a pair of identifiable central neurons in certain fish and amphibians. in the axolotl (ambystoma mexicanum), the large vestibular axons form club endings on only one portion of one dendrite of the mauthner cell. during development, this specific distribution might result from nothing more than ...	1991	1761755
a light and electron microscopic study of the development of the mauthner cell and vestibular nerve in the axolotl.	vestibular axons form synapses on a restricted area of the lateral dendrite of the mauthner cell, a large, identified brainstem neuron found in fish and amphibians. the differentiation of the vestibular nerve, medullary neuropil, and mauthner cell of the axolotl (ambystoma mexicanum) was studied to understand better the means by which this synaptic specificity arises. the mauthner cell first extends a medial process and then a lateral dendrite. the latter initially elongates as a simple process ...	1991	1761753
axonal transport and release of transferrin in nerves of regenerating amphibian limbs.	transferrin, a plasma protein required for proliferation of normal and malignant cells, is abundant in peripheral nerves of birds and mammals and becomes more concentrated in this tissue during nerve regeneration. we are testing the hypothesis that this factor is involved in the growth-promoting effect of nerves during the early, avascular phase of amphibian limb regeneration. a sensitive enzyme-linked immunosorbent assay for axolotl transferrin was developed and used to determine whether this p ...	1991	1916015
measures of phototaxis and movement detection in the larval salamander.	in this investigation, we describe two precise tests of visual function that integrate quasinatural situations with time-lapse video recording and infrared computerized monitoring of activity to assess movement detection and phototaxic tendencies, respectively. four groups of larvae from a. punctatum, a. tigrinum, a. mexicanum, and a mutant albino axolotl were tested in an alley containing light and dark halves and lined with infrared sensors to monitor their phototaxic response. a. punctatum sh ...	1991	1801024
heart development in normal and cardiac-lethal mutant axolotls: a model for the control of vertebrate cardiogenesis.	the mechanisms which regulate myocardial differentiation are poorly understood. the cardiac-lethal (c) mutant of ambystoma mexicanum, in which the heart never begins to beat, provides a valuable model system for studying this process. using an in vitro assay, we examine the nature of the defect in c/c embryos and find (contrary to previous reports) that the inductive endoderm is not affected by the mutation. rather, the pre-cardiac mesoderm is directly affected by the c gene and is incapable of ...	1991	1959711
well-defined growth factors promote cardiac development in axolotl mesodermal explants.	the effect of growth factors on the formation of cardiac mesoderm in the urodele, ambystoma mexicanum (axolotl), has been examined using an in vitro explant system. it has previously been shown that cardiac mesoderm is induced by pharyngeal endoderm during neurula stages in urodeles. in this study, explants of prospective cardiac mesoderm from early neurula stage embryos rarely formed beating cardiac tissue in culture. when transforming growth factor beta-1 (tgf-beta 1) or platelet-derived growt ...	1991	1935698
extracellular matrix of the developing heart in normal and cardiac lethal mutant axolotls, ambystoma mexicanum.	as part of an ongoing study of heart development in normal and cardiac lethal mutant axolotls (mexican salamanders) we examined the extracellular matrix (ecm) by microscopical methods. with scanning electron microscopy we are unable to detect ecm on the apical surface of cells of the early cardiogenic mesoderm. during the period of lateral plate migration, which coincides with the period of cardiogenic induction of mesoderm by anterior endoderm, there is little ecm, aside from some microfibrils, ...	1991	1867413
radial glia give rise to perinodal processes.	nodes of ranvier in the central nervous system in mammals are characterized by the presence of perinodal astrocytic processes. this study examines the association between processes of radial glia and the axolemma at nodes of ranvier in the spinal cord of the mature axolotl, an animal in which radial glia represent a large portion of the total glial population. the radial glial cells have their cell bodies located close to the central canal. those situated dorsal to the canal send long processes ...	1991	1893250
retinoic acid does not induce formation of cilia on the surface of wound epithelial cells in axolotls.	it has been reported that vitamin a palmitate induces the production of cilia on the epidermal cells of the regenerating axolotl limb, and the formation of crevices in the epidermal surface. the aim of the present investigation was to reexamine under well defined conditions the potential of retinoids to evoke the above described metaplastic changes. in order to achieve our purpose we administered axolotls with retinoic acid for 2, 4, 6, 8, and 10 days after limb amputation. the young regenerates ...	1991	1913848
retinoic acid stimulates neurite outgrowth in the amphibian spinal cord.	there is increasing evidence that retinoic acid (ra), a vitamin a metabolite, plays a role in the development of the nervous system. here we specifically test this notion by examining the effect of ra on neurite outgrowth from explanted segments of the axolotl spinal cord. we show that there is a threshold concentration in the region of 0.1-1 nm above which neurite outgrowth is stimulated 4-5 fold. retinol, by contrast, only stimulated the migration of glial cells from the explants. using hplc w ...	1991	1850835
the respecification of limb pattern by new synthetic retinoids and their interaction with cellular retinoic acid-binding protein.	we describe here experiments to examine the role of cellular retinoic-acid-binding protein (crabp) during the induction of limb duplication in the chick limb bud and regenerating axolotl limb by retinoids. a newly synthesised class of retinoic acid analogues have been used because among them, some have been specifically designed with the property of binding to the retinoic acid receptors, but not to crabp. we can thus test whether binding to crabp is an obligatory step during limb respecificatio ...	1991	1655545
localization of smooth-muscle markers in the ovaries of some ectothermic vertebrates.	in the present study, we have localized desmin and alpha-smooth-muscle actin in the ovaries of the zebrafish, the axolotl, and the red-eared turtle, using the unlabelled antibody peroxidase-antiperoxidase technique. in the axolotl ovary both smooth-muscle markers were demonstrated in cord-like structures, extended along ovarian blood vessels, and in some inner ovarian epithelium cells. in the ovaries of the teleost, smooth-muscle-like cells are detected in a suspensory apparatus formed by venous ...	1991	2048748
evidence for enkephalin- and endorphin-immunoreactive cells in the anterior pituitary of the axolotl ambystoma mexicanum.	an immunohistochemical study of opioid peptides in the hypophysis of the axolotl, ambystoma mexicanum, was carried out with antisera against leu-enkephalin, beta-endorphin, met-enkephalin, and dynorphin a (1-8). we found leu-enkephalin immunoreactivity in some fibers of the neural lobe and the median eminence. in contrast to previous reports on mammals and other vertebrates, we found leu-enkephalin immunoreactivity in many cells scattered throughout the anterior lobe. as in other vertebrates, th ...	1991	1674748
expression of the 9g1 antigen in the apical cap of axolotl regenerates requires nerves and mesenchyme.	monoclonal antibody 9g1 (mab 9g1) is reactive to the wound epithelium of axolotl larvae and therefore provided the opportunity to examine the interaction between the wound epithelium, nerves, and blastemal mesenchyme during axolotl limb regeneration. in unamputated limbs, mab 9g1 is reactive to most or all cells of the dermis, skeletal elements, blood vessels, and nerves, to a few unidentified cells in muscle, and to none in epidermis. during regeneration of axolotl limbs, mab 9g1 reacts strongl ...	1991	2005423
nucleotide sequence of a cdna encoding wnt-1 of the mexican axolotl ambystoma mexicanum.		1991	2017393
organization of motor units in the axolotl: a continuously growing animal.	the characteristics of motor units in the iliotibialis posterior muscle of the axolotl hindlimb are described. tension recording and intracellular electrophysiological methods demonstrate that the physiological properties of the population of motor units are continuously distributed rather than grouped into a series of discrete types. overlap between motor units occurs and this is positively correlated with motor unit size but negatively correlated with differences in time to peak tension. immun ...	1991	2013646
continuous growth of the motor system in the axolotl.	during growth of the axolotl, motor neurons, and muscle fibres are added to the motor system. by double labelling neurons with tritiated thymidine and retrogradely transported hrp, we show that some motor neurons are born at postembryonic stages. further analysis of motor neurons with the aid of hrp reveals this population of newly born cells relatively frequently in small (5-7 cm long) axolotls, but only rarely in large (7-13 cm long) axolotls. evidence is presented that suggests that these imm ...	1991	2013645
structural changes in the proximal tubule of the short-toes axolotl mutant.	a recessive lethal mutation in axolotls that involves the kidneys, the mullerian ducts and the limbs was described by humphrey (1967). in the present experiments, we have examined the structural defects that lead to kidney malfunction and subsequent death in homozygous mutants and compared the defects with those observed in other axolotls lacking this mutant gene. the ultrastructure of the mesonephric kidney was studied in homozygous s/s short-toes axolotls with ascites and/or edema and hemorrha ...	1991	18621179
distribution of sulfhydryloxidase (sox) immunoreactivity in the testis of the axolotl (ambystoma mexicanum) (amphibia, urodela).	immunohistochemical localization of sulfhydryloxidase (sox) has been examined in the testis of the axolotl (ambystoma mexicanum). the urodelan testis contains germ cells in various phases of differentiation from primordial germ cells to mature spermatozoa. sox immunoreactivity is present in mitochondria of primordial germ cells and primary spermatogonia and declines within the population of secondary spermatogonia, suggesting, that the antibody used to localize sox may serve to estimate the deve ...	1991	18621168
endothelial nuclear bulging: morphological evidence for an intraglomerular perfusion regulating mechanism in the axolotl.	kidneys of the axolotl (ambystoma mexicanum: urodela, amphibia) have been investigated by light and electron microscopy as well as microvascular corrosion casting. numerous glomerular endothelial nuclei bulge into the glomerular capillary lumen. it is concluded that these cells virtually stop the blood-flow in the respective vessel by blockage of erythrocyte passage. a proposal for an intraglomerular regulation mechanism of capillary perfusion (and thus filtration) by endothelial isometric contr ...	1991	18621164
localization of calmodulin in epidermis and skin glands: a comparative immunohistological investigation in different vertebrate species.	the study deals with the immunolocalization of calmodulin-reactive epithelial cells in different vertebrates (tinca tinca, ambystoma mexicanum, xenopus laevis, rana ridibunda, columba domestica, sus scrofa domestica, homo sapiens sapiens). the immunoperoxidase technique was performed on acetone fixed frozen sections using monoclonal (bf8) and polyclonal (acam) anti-calmodulin antibodies. we were able to differentiate 2 major types of staining patterns: 1. a more superficial epidermal staining in ...	1991	1718122
hydrogen ion currents in rat alveolar epithelial cells.	alveolar epithelial cells isolated from rats and maintained in primary culture were studied using the whole-cell configuration of the "patch-clamp" technique. after other ionic conductances were eliminated by replacing permeant ions with n-methyl-d-glucamine methanesulfonate, large voltage-activated hydrogen-selective currents were observed. like h+ currents in snail neurons and axolotl oocytes, those in alveolar epithelium are activated by depolarization, deactivate upon repolarization, and are ...	1991	1722118
[adaptative differential maturation of neurohypophyseal provasotocin in amphibians: presence of hydrin 2(vasotocinyl-glycine) in anura but not in urodela].	occurrence of hydrin 2 (vasotocinyl-glycine), an intermediate in the provasotocin processing, has been shown in the neurointermediate lobe of the pituitary of semi-aquatic or terrestrial amphibian species belonging to the order anura, namely rana esculenta, r. temporaria, r. pipiens (ranidae), and bufo bufo, b. marinus, b. ictericus (bufonidae). in contrast hydrin 2 appears absent in species belonging to the order urodela, namely the axolotl ambystoma mexicanum (ambystomidae) and the pleurodele ...	1991	1756409
reinvestigation of dna ligase i in axolotl and pleurodeles development.	we have recently shown that the exclusion process causing the replacement of dna ligases ii by dna ligase i in amphibian eggs after fertilization does not occur in the case of xenopus laevis [hardy, s., aoufouchi, s., thiebaud, p., and prigent, c., (1991) nucleic acids res. 19, 701-705]. since this result is in contradiction with the situation reported in axolotl and pleurodeles we decided to reinvestigate such results in both species. three different approaches have been used: (1) the substrate ...	1991	1886765
dna ligase i from xenopus laevis eggs.	we have purified the major dna ligase from xenopus laevis eggs and raised antibodies against it. estimates from sds page indicate that this dna ligase is a 180 kda protein. this enzyme is similar to the mammalian type i dna ligase which is presumed to be involved in dna replication. we have also analysed dna ligase activity during x. laevis early development. unfertilized eggs contain the highest level of activity reflecting the requirement for a large amount of dna replicative enzymes for the p ...	1991	2017356
sequence, organization and transcriptional analysis of a gene encoding a u1 snrna from the axolotl, ambystoma mexicanum.	amu1, a dna fragment containing a u1 small nuclear rna (snrna)-encoding gene, was isolated from the axolotl, ambystoma mexicanum. although this u1 snrna, produced in axolotl oocytes, exhibits the lowest degree of sequence conservation among vertebrates, its secondary structure is maintained by a number of compensatory base changes. the proximal sequence element (pse) is only weakly similar to that of the previously characterized xenopus laevis pse. exchanging either the entire upstream regions w ...	1991	2022330
acidic fibroblast growth factor is present in regenerating limb blastemas of axolotls and binds specifically to blastema tissues.	the growth of regenerating limbs of amphibians depends upon proliferation of the blastema cells that accumulate beneath the epidermal cap. the epidermal cap is known to be mitogenic for the blastema cells. we have extracted a mitogenic activity from both the mesenchymal and epidermal (epidermal cap) components of cone stage blastemas which is retained on heparin-sepharose and elutes with 1.15 m nacl. this fraction stimulates neurite outgrowth of pc12 cells and [3h]thymidine incorporation into cc ...	1991	2040374
effects of fetal bovine serum and serum-free conditions on white and dark axolotl neural crest explants.	neural crest cells from both white mutant and dark (wildtype) axolotls (ambystoma mexicanum) were cultured in increasing concentrations of fetal bovine serum (fbs; 2 to 20%). for each explant, the total number of cells that migrated and the percent of differentiated melanophores were recorded. at concentrations of fbs above 2% melanophore differentiation was essentially equivalent (32 to 59%) for both the white and dark neural crest cultures, but subtle differences in cell behavior and different ...	1991	2071543
ectopic expression of a genomic fragment containing a homeobox causes neural defects in the axolotl.	an axolotl (ambystoma mexicanum) genomic fragment containing the ahox1 homeobox was placed under the control of the mouse hsp68 promoter, which seems to function constitutively in the axolotl. the resulting construct was injected into fertilized axolotl eggs to see if it would perturb development. of the injected embryos, 20% showed severe reduction of the anterior neural plate. later in development, these embryos had small heads, no eyes, and appeared to lack the normal regionalization of the b ...	1991	1680349
streptomycin blocks the postsynaptic effects of excitatory amino acids on the vestibular system primary afferents.	it has been suggested that streptomycin might be an antagonist of the glutamate receptors, and that it selectively blocks quisqualic acid receptors. we studied whether streptomycin blocks the responses to excitatory amino acid agonists on the vestibular system primary afferents, and if it allows us to differentiate between kainate (ka) and quisqualate (qa) receptor mediated responses. the experiments were performed in the axolotl (ambystoma tigrinum). intra- and extracellular records of the elec ...	1991	1786535
brain-capillary architecture of the newt, triturus cristatus carnifex (caudata: salamandridae): scanning electron-microscopical study of vascular corrosion casts.	the brain-microvascular architecture of the newt (triturus cristatus carnifex) was studied by scanning electron-microscopical examination of microvascular corrosion casts. it is characterized at the leptomeningeal level by a superficial network of single vessels that leave the meningeal sheath to form hairpin-shaped capillary loops. these loops penetrate the nervous parenchyma to varying depths and are variously bent, inclined, and twisted. each hairpin-like loop consists of descending and ascen ...	1991	29865580
the vascular structure of the kidney of the neotenous axolotl and its metamorphosed counterpart.	the renal vascular and glomerular structures of the kidney of neotenous and experimentally metamorphosed axolotls (ambystoma mexicanum: amphibia, urodela) are investigated using light, transmission electron, and scanning electron microscopy of critical-point dried specimens and vascular corrosion casts. the blood vascular system of the kidney in the axolotl is generally similar to that in other urodeles. the glomeruli are comparatively large and distincly ovoid (mean size 267 × 201 μm). glomerul ...	1992	29865583
reptilian class i major histocompatibility complex genes reveal conserved elements in class i structure.	the polymerase chain reaction was used to isolate clones with class i major histocompatibility complex sequences from fish (carp), amphibian (axolotl), and two species of reptile (lizard and snake). the lizard and snake clones were used to isolate class i cdna clones. all the sequences showed the expected evolutionary relatedness. the carp and axolotl clones and one lizard cdna clone lacked the first cysteine in the alpha 3 domain which in other class i heavy chains forms an intradomain disulfid ...	1992	1612650
the differential transcriptional activity of two amphibian u1 small-nuclear rna genes correlates with structural differences in the proximal sequence element.	we previously analyzed the transcription of an axolotl u1 small-nuclear rna (snrna) gene (amu1) by microinjection into xenopus laevis oocytes. in such an assay, amu1 showed a low template activity compared to that of an x. laevis u1 snrna gene (xlu1b2). swapping the proximal sequence element (pse) with that of xlu1b2 was required for amu1 to acquire a transcription level equal to that of xlu1b2. in the present work, we examine the functional importance of the nucleotides that are common or diffe ...	1992	1735429
valproic acid induced abnormal development of the central nervous system of three species of amphibians: implications for neural tube defects and alternative experimental systems.	embryos of ambystoma mexicanum, xenopus laevis, and hyperolius viridiflavus taeniatus were exposed to various concentrations of valproic acid (vpa: 0.1, 1.5, 10 mm) from blastula stage (s) 9 on up to advanced gastrulation of control embryos (s 11 1/2-12). at 10 and 5 mm vpa early development was affected in all species tested. however, the most pronounced effects occurred in ambystoma: the neural folds appeared delayed and showed a flattened and wavy shape; the neural tube was not formed and emb ...	1992	1363963
evolution of vertebrate igm: complete amino acid sequence of the constant region of ambystoma mexicanum mu chain deduced from cdna sequence.	cdna clones coding for the constant region of the mexican axolotl (ambystoma mexicanum) mu heavy immunoglobulin chain were selected from total spleen rna, using a cdna polymerase chain reaction technique. the specific 5'-end primer was an oligonucleotide homologous to the jh segment of xenopus laevis mu chain. one of the clones, jha/3, corresponded to the complete constant region of the axolotl mu chain, consisting of a 1362-nucleotide sequence coding for a polypeptide of 454 amino acids followe ...	1992	1382992
isolation of lactose-binding lectins from axolotl (ambystoma mexicanum).	1. lactose-inhibitable hemagglutination activity was identified in extracts of axolotl (ambystoma mexicanum) larvae. 2. two types of lectin were isolated from extracts by affinity chromatography on lactose-sepharose. 3. a thiol-independent lectin of subunit mol. wt 15 kda and a thiol-dependent lectin of subunit mol. wt 18 kda were identified. 4. the 15 kda and a 18 kda polypeptides were weakly reactive with polyclonal anti-human galaptin serum.	1992	1424562
developmental expression of the xenopus int-2 (fgf-3) gene: activation by mesodermal and neural induction.	we have used a probe specific for the xenopus homologue of the mammalian proto-oncogene int-2 (fgf-3) to examine the temporal and spatial expression pattern of the gene during xenopus development. int-2 is expressed from just before the onset of gastrulation through to prelarval stages. in the early gastrula, it is expressed around the blastopore lip. this is maintained in the posterior third of the prospective mesoderm and neuroectoderm in the neurula. a second expression domain in the anterior ...	1992	1425349
neuron-specific enolase-like immunoreactivity in the vertebrate retina: selective labelling of müller cells in anura.	neuron-specific enolase (nse) immunocytochemistry was carried out in retinae of goldfish, axolotl, clawed frog, cane toad, lizard, chick, guinea-pig, rabbit, rat, cat and human. with the exception of anura, strong immunoreactivity was seen in the large ganglion, amacrine cells and horizontal cells of the retina in all of the other species. photoreceptors were found to be labelled in the rat and human retina and only one cone type in rabbit. photoreceptor pedicles and ellipsoids were stained in t ...	1992	1459864
reproducible proliferative responses of salamander (ambystoma mexicanum) lymphocytes cultured with mitogens in serum-free medium.	there are several reports that proliferative responses (tritiated thymidine incorporation (3htdr)) of salamander splenocytes cultured with phytohemagglutinin-p (pha) or concanavalin a (con a) in 1% fetal bovine serum (fbs)-supplemented medium are either statistically insignificant or never approach the magnitude typically observed in similarly treated cultures of frog lymphocytes. the present study confirms these findings, but also reports highly significant and reproducible pha-induced prolifer ...	1992	1473594
phylogeny of the third component of complement, c3: analysis of the conservation of human cr1, cr2, h, and b binding sites, concanavalin a binding sites, and thiolester bond in the c3 from different species.	the third component of complement, c3, binds to several other complement proteins. to study the diverse reactivities of c3, we analyzed the conservation of structural and functional features in the c3 from different species. first, we developed a method to purify swine (po), rabbit (rb), mouse (mo), cobra (co), xenopus (xe), axolotl (ax), and trout (tr) c3 from plasma. this involved protein precipitation by polyethylene glycol, followed by anion-exchange, gel filtration, and cation exchange chro ...	1992	1535601
thyroid hormone receptors and iodothyronine deiodinases in the developing mexican axolotl, ambystoma mexicanum.	the mexican axolotl, ambystoma mexicanum, is a neotenous salamander that rarely undergoes anatomical metamorphosis, but can be induced to do so by administration of thyroxine (t4). the neoteny appears to be due primarily to low levels of plasma t4 secondary to a low rate of secretion of thyroid-stimulating hormone. however, other factors may also be involved. in anuran amphibia, metamorphosis is accompanied by alterations in thyroid hormone receptor concentration and marked changes in the activi ...	1992	1563619
the marginal zone of the 32-cell amphibian embryo contains all the information required for chordamesoderm development.	the formation of the amphibian organizer is evidenced by the ability of cells of the dorsal marginal zone (dmz) to self-differentiate to form notochord and to induce the formation of other axial structures from neighboring regions of the embryo. we have attempted to determine when these abilities are acquired in the urodele, ambystoma mexicanum (axolotl), and in the anuran, xenopus laevis, by removing the mesodermalizing influence of the vegetal hemisphere at different stages of development and ...	1992	1583451
the stopping response of xenopus laevis embryos: behaviour, development and physiology.	1. when xenopus laevis embryos swim into an obstruction they usually stop. this stopping response to stimulation on the head is present from stage 28 to 45. at stage 37/38 it is more reliable in restrained than in free-swimming animals, and to stimuli to the cement gland than to the head skin. 'fictive' swimming also stops reliably after the same stimuli but struggling and 'fictive' struggling do not. 2. discharge of deformation-sensitive trigeminal sensory neurons in response to pressure on the ...	1992	1583603
t-cell-specific membrane antigens in the mexican axolotl (urodele amphibian).	comparative analysis of sds-page patterns of axolotl spleen cells membrane detergent lysates showed important discrepancies between control and thymectomized animals. among these, a 38-kd protein band, which appeared as a major protein in controls, was not or poorly expressed after thymectomy. a rabbit antiserum (l12) raised against the 38-kd eluted band labeled in indirect immunofluorescence 80-86% of thymocytes and 40-46% of mig- lymphoid cells in the spleen. the anti-38-kd antibodies stained ...	1992	1627952
monoclonal antibody st1 identifies an antigen that is abundant in the axolotl and newt limb stump but is absent from the undifferentiated regenerate.	monoclonal antibodies (mab) utilized in regeneration studies to date identify antigens that are up-regulated in the blastema. we obtained a monoclonal antibody, designated st1 (stump 1), that is reactive to an extracellular matrix (ecm) antigen exhibiting the opposite distribution; st1 is an abundant antigen of the limb stump soft tissues but is absent from within the blastema. the border between abundance and absence of mab st1 reactivity was sharp and extended as a concavity into the stump. th ...	1992	1279094
distribution and innervation of lateral line organs in the axolotl.	the lateral line system in axolotls consists of three types of receptors and the cranial nerves that innervate them. superficial neuromasts, which are mechanoreceptors, are distributed in lines on both the head and trunk. eight cephalic and three trunk lines can be distinguished on the basis of their innervation and differences in the orientation of the major axes of their neuromasts. a combination of histological techniques reveals that five separate pairs of cranial nerves innervate the neurom ...	1992	1484121
structural and endocytotic differences of fibroblasts and macrophages in the tail fin of amphibian larvae during metamorphosis.	different features in the fibroblasts and the macrophages, which are prominent cell types in the dermis of the dorsal tail fin of the larval axolotl, ambystoma mexicanum, and the tadpole, rana japonica, were examined by light and electron microscopy. at the non-metamorphic stages, the cytoplasm of the macrophage, loaded with numerous lysosomes, is generally located in the cell periphery. outstanding was the presence of many ruffles or microvillous projections of different shapes and sizes in the ...	1992	1482609
leydig cells in the lingual epithelium of the axolotl, ambystoma mexicanum, are immunoreactive for serotonin.	the leydig cells in the lingual epithelium of the axolotl were investigated by immunohistochemistry using serotonin antiserum. serotonin-immunoreactivity was found in their secretory granules. the physiological role of serotonin in the leydig cell, a type of exocrine cell, is unknown.	1992	1295874
selective innervation of foreign muscles following damage or removal of normal muscle targets.	the restoration of a normal pattern of neural connectivity following nerve injury depends upon the selective reinnervation of appropriate postsynaptic targets. previous studies suggest that, in the neuromuscular system, recognition between regenerating motoneurons and target muscles depends upon the positions of origin of the motoneurons and muscles. in axolotls, portions of the motor pools of adjacent muscles overlap. we found that, following removal of a pair of adjacent hindlimb muscles, ante ...	1992	1383284
primary structure of neutral and acidic oligosaccharide-alditols derived from the jelly coat of the mexican axolotl. occurrence of oligosaccharides with fucosyl(alpha 1-3)fucosyl(alpha 1-4)-3-deoxy-d-glycero-d-galacto-nonulosonic acid and galactosyl(alpha 1-4)[fucosyl(alpha 1-2)]galactosyl(beta 1-4)-n-acetylglucosamine sequences.	six major neutral and acidic oligosaccharide-alditols were prepared from the jelly coat of mexican axolotl eggs. these compounds were demonstrated to contain 3-deoxy-d-glycero-d-galacto-nonulosonic acid (dnloa) and l-fucose (fuc). the structures of the six major oligosaccharides were established as follows: [sequence: see text]	1992	1499572
the mutant axolotl short toes exhibits impaired limb regeneration and abnormal basement membrane formation.	the mutant axolotl short toes develops with abnormal kidneys, mullerian ducts, and limbs and provides one of the few experimental systems for developmental studies in amphibia. the present paper describes another deviation from this animal's normal physiology, which is very characteristic of the wild type: amputated limbs of short toes fail to regenerate. a blastema is formed but differentiation does not occur. detailed histological analysis provides evidence of abnormal formation of the basemen ...	1992	1608961
caenogenesis, developmental variability, and evolution in the carpus and tarsus of the marbled newt triturus marmoratus.	in this paper, after a comparative analysis of the development of triturus marmoratus, we explore the existence of caenogenetic events and their ontogenetic and phylogenetic consequences. the adult morphology of the triturus marmoratus limb, in terms of number and spatial arrangement of skeletal elements, agrees with the general pattern of urodeles. the congruence in the typical pattern of adult morphology does not hint at the striking differences in embryonic development. these differences can ...	1992	28568662
histochemical study of the heart of the axolotl (ambystoma mexicanum).	we have investigated the presence of cells containing monoamines, substance p, and neuron-specific enolase (nse) in the heart and in the pericardial wall of a urodele amphibian, the axolotl. fibers containing substance p-like immunoreactivity were present in the heart but not in the pericardial wall. also present in the heart were small branched cells, which stained metachromatically with toluidine blue. similar cells were found in the peritoneum and were tentatively identified as mast cells. ns ...	1992	1376564
ganglia implantation as a means of supplying neurotrophic stimulation to the newt regeneration blastema: cell-cycle effects in innervated and denervated limbs.	regulation of blastema cell proliferation during amphibian limb regeneration is poorly understood. one unexplained phenomenon is the relatively low level of active cell cycling in the adult newt blastema compared to that of larval axolotls. in the present study, we used ganglia implantation as a means of "superinnervating" normally innervated adult newt blastemas to test whether blastema cell subpopulations are responsive to nerve augmentation. the effectiveness of implanted ganglia to provide n ...	1992	1583454
inhibition of neural crest cell differentiation by embryo ectodermal extract.	the white mutation in mexican axolotls has long been thought to be a defect associated with the embryonic extracellular environment, but not with embryonic neural crest cells. thus it was believed that pigment cells in white axolotls disappear from the skin during early development, not because they are intrinsically defective but because they have no choice but to move into an unfavorable environment. we present evidence to suggest that: (1) white neural crest cells are in fact intrinsically di ...	1992	1569410
morphological features of the myenteric plexus of the stomach of the axolotl, ambystoma mexicanum, revealed by immunocytochemistry.	the general morphology of the intramural innervation of the myenteric plexus of the axolotl stomach has been investigated using antisera raised against neuron-specific enolase and a microtubule-associated protein. additionally, the occurrence of serotonin and several peptidergic neurotransmitter/neuromodulator substances was studied. immunoreactivity for galanin, vasoactive intestinal polypeptide, substance p and neuromedin u was found in both fibres and intrinsic perikarya, whereas the serotoni ...	1992	1375207
retinoic acid-induced change in anteroposterior positional identity in regenerating axolotl limbs is dose-dependent.	retinoic acid (ra) induces pattern duplication in the proximodistal (pd) axis of axolotl limb regenerates. the effect is dose-dependent, with the maximum extent of duplication being evoked at a dose of 150 micrograms ra/g body weight. the same dose of ra induces maximum pattern completion in the anteroposterior (ap) axis of regenerating anterior half or double anterior half limbs. ra inhibits the regeneration of posterior half or double posterior half limbs (kim, w.s., and stocum, d.l. [1986] de ...	1992	1600247
effects of tunicamycin on retinoic acid induced respecification of positional values in regenerating limbs of the larval axolotl, ambystoma mexicanum.	urodele amphibians possess a remarkable ability to regenerate limbs following experimental or accidental amputation. since only those parts of the limb distal to the plane of amputation usually regenerate, this suggests the existence of level-specific positional values within the cells of the limb. vitamin a and other retinoids respecify the positional values of regenerating limbs such that structures proximal to the actual plane of amputation are formed in the regenerating limb producing proxim ...	1992	1581606
reorganization of the ependyma during axolotl spinal cord regeneration: changes in intermediate filament and fibronectin expression.	changes in intermediate filament content and extracellular matrix material showed that the injury response of ependymal cells in lesioned axolotl spinal cord involves an epithelial-to-mesenchymal transformation, and that fibrous astrocytes are excluded from the remodeling lesion site. antibody localization was used to visualize cytokeratin-, vimentin-, and glial fibrillary acidic protein- (gfap-) containing intermediate filaments, as well as the adhesive glycoprotein fibronectin. in normal axolo ...	1992	1374657
transient developmental expression of igy and secretory component like protein in the gut of the axolotl (ambystoma mexicanum).	we previously reported that a primitive vertebrate, the mexican axolotl (amphibian, urodela) synthesizes two classes of immunoglobulins. igm are present in serum early in the development, and represent the bulk of specific antibody synthesis after an antigenic challenge. igy occur in the serum later during the development, and are relatively insensitive to immunization. we demonstrate in the present work, using immunofluorescence with specific mabs, that igy are expressed in the gut epithelium, ...	1992	1627950
characterization of fibroblast growth factor binding in regenerating limb blastemas of axolotls.		1992	1614427
axonal release of transferrin in peripheral nerves of axolotls during regeneration.		1992	1614426
melanotropin as a potential regulator of pigment pattern formation in embryonic skin.	frozen tissue sections of developing axolotl embryos were labeled by indirect immunofluorescence with anti-alpha-msh. anti-msh immunoreactivity is first detectable in embryos when neural crest cells are migrating from the neural tube. antibody labeling is visible around the lateral and ventral edges of the neural tube and in the embryonic ectoderm. as development progresses, the amount of labeling increases greatly, particularly in developing ectoderm. western blots of soluble proteins extracted ...	1992	1329074
the development of the neural crest in amphibians.	our review deals with the development of the neural crest (nc) in amphibians. we will consider relevant aspects of evolution, ontogeny, migration and differentiation, and investigate principal problems such as the regulation of nc cell determination, pathway selection and destination recognition. earlier data and more recent findings will be presented. the nc probably evolved about 440 million years ago from the anlagen of epidermal nerve plexuses in protochordates. in urodele amphibians, the pr ...	1993	8297037
reaction-diffusion control of heart development: evidence for activation and inhibition in precardiac mesoderm.	in axolotl embryos homozygous for the cardiac-lethal (c) gene, the heart never begins to beat. recently, we demonstrated that the c gene affects the heart mesoderm directly, making the latter incapable of responding to normal inductive stimuli. based on these results, we proposed that a reaction-diffusion mechanism controls the later stages of vertebrate cardiogenesis. in the present study, we use a series of transplantations to examine the precardiac mesoderm of wild-type and cardiac-lethal mut ...	1993	8253281
test of a model for the effects of retinoic acid on urodele limb regeneration.	previous studies have shown that in axolotls (ambystoma mexicanum), retinoic acid (ra) treatment evokes pattern completion in limb regenerates derived from anterior and dorsal half zeugopodia (lower arms and legs), but causes regenerative failure in posterior and ventral half zeugopodia. pattern completion in anterior and dorsal half limbs may be explained by postulating that intercalary regeneration occurs in the antero-posterior (ap) and dorsoventral (dv) axes between blastema cells that are p ...	1993	8305708
a histological processing technique that preserves the integrity of calcified tissues (bone, enamel), yolky amphibian embryos, and growth factor antigens in skeletal tissue.	we have devised a processing technique to embed calcified tissues, such as bone and tooth enamel, in paraffin, to preserve the delicate antigenic sites of molecules such as growth factors. the same technique, omitting the decalcification step, allows delicate tissues, such as axolotl embryos (ambystoma mexicanum) containing large yolk masses, to be easily handled during tissue processing and to be serially sectioned. specimens were all fixed in periodate-lysine-paraformaldehyde (plp) fixative at ...	1993	7689084
restoration of motor unit properties and fiber type distribution in reinnervated axolotl skeletal muscle.	the contractile properties of functionally isolated motor units and the muscle fiber type distribution of reinnervated iliotibialis posterior muscles were examined in axolotls (ambystoma mexicanum) 7 to 12 months after complete transection of the hind limb nerve trunks. motor units were continuously distributed with respect to size and contractile speeds and there was a positive correlation between motor unit size and twitch:tetanus ratio. the degree of overlap between motor units was positively ...	1993	8344452
[fertilization and development of axolotl oocytes with already grey crescent experimentally formed during their maturation].	pigmented axolotl coelomic oocytes were induced to form a gray crescent by simultaneous action of a gravity vector and of a heat-shock (36 +/- 0.5 degree c during 10-15 min), according to a previously described method. those oocytes were subsequently reintroduced into the coelomic cavity of an albino recipient female, which had been previously inseminated. among fertilized treated oocytes, more than 75% developed into embryos whose dorsal side corresponded to the gray crescent-forming area of th ...	1993	8044696
macrophage response during axonal regeneration in the axolotl central and peripheral nervous system.	we have used a monoclonal antibody (5f4) and griffonia lectin to study the recruitment of macrophages after crushing axolotl central and peripheral axons. in both cases axonal regeneration begins within one to two days and, in the cns, proceeds at a rate of about 0.05 mm per day. however, in the spinal cord, macrophage entry is restricted to the lesion site whilst in peripheral nerves macrophages rapidly enter the distal nerve stump after injury. these results suggest that the role (if any) play ...	1993	8332261
molecular analysis of the wnt-1 proto-oncogene in ambystoma mexicanum (axolotl) embryos.	to analyze wnt-1 expression during neurulation in urodele embryos, we have isolated a wnt-1 cdna clone, awnt-1, from an ambystoma mexicanum (axolotl) neurula-stage cdna library. awnt-1 codes for a protein of 369 amino acids rich in cysteine residues, is preceded by a hydrophobic leader peptide sequence and contains four possible sites for n-linked glycosylation. the temporal expression profile of awnt-1 was analyzed by reverse transcription-polymerase chain reaction (rt-pcr). awnt-1 expression i ...	1993	8508949
metamorphic changes in glycolipids and myelin proteins and 2',3'-cyclic nucleotide 3'-phosphohydrolase in bullfrog and axolotl brains.	the metamorphic changes in levels of glycolipids and myelin proteins and 2',3'-cyclic nucleotide 3'-phosphohydrolase (cnp) in the brains of bullfrog tadpoles, adult frogs, and axolotls were investigated, with particular emphasis on myelin maturation. the concentrations of cerebroside, sulfatide, and galactosyldiacylglycerol gradually increased from the onset of prometamorphosis throughout the active metamorphic period and then greatly increased after metamorphosis was completed. the ratio of glu ...	1993	8386225
transcellular labeling by dii demonstrates the glossopharyngeal innervation of taste buds in the lingual epithelium of the axolotl.	innervation of the axolotl lingual epithelium by the glossopharyngeal nerve was examined to reveal its sensory target cells. the carbocyanine dye dii was applied to the nerve stump in the tongue fixed with paraformaldehyde. after a diffusion period of several months, the tongues were examined with a conventional epifluorescence microscope and a confocal laser scanning microscope (lsm) in wholemounts or preparations sectioned with a vibratome. beneath the epithelium the labeled nerve fibers sprea ...	1993	8320345
pit organs in axolotls: a second class of lateral line neuromasts.	the lateral line system of axolotls (ambystoma mexicanum) consists of mechanoreceptive neuromasts and electroreceptive ampullary organs. all neuromasts in salamanders are located superficially and are organized into lines that are homologous to canal neuromasts in fishes. ampullary organs are confined to the head and generally are located adjacent to the lines of superficial neuromasts. axolotls, however, also possess a third class of receptors; these form restricted patches on the head and are ...	1993	8315607
brachially innervated ectopic hindlimbs in the chick embryo. i. limb motility and motor system anatomy during the development of embryonic behavior.	the functional status of brachially innervated hindlimbs, produced by transplanting hindlimb buds of chick embryos in place of forelimb buds, was quantified by analyzing the number and temporal distribution of spontaneous limb movements. brachially innervated hindlimbs exhibited normal motility until e10 but thereafter became significantly less active than normal limbs and the limb movements were more randomly distributed. contrary to the findings with axolotls and frogs, functional interaction ...	1993	8492107
replacement of lateral line sensory organs during tail regeneration in salamanders: identification of progenitor cells and analysis of leukocyte activity.	it has been proposed that supporting cells may be the progenitors of regenerated hair cells that contribute to recovery of hearing in birds, but regeneration is difficult to visualize in the ear, because it occurs deep in the skull. hair cells and supporting cells that are comparable to those in the ear are present in lateral line neuromasts, and in axolotl salamanders these cells are accessible to microscopic observation in vivo. after amputation of a segment of the tail that contains neuromast ...	1993	8441001
stability of positional identity of axolotl blastema cells in vitro.	previous grafting experiments have demonstrated that cells from non-contiguous positions within developing and regenerating limbs differ in a property referred to as positional identity. the goal of this study was to determine how long the positional identity of axolotl limb blastema cells is stable during culture in vitro. we have developed an assay for posterior positional properties such that blastema cells can be cultured and then grafted into anterior positions in host blastemas, to determi ...	1993	28305994
insulin counters the glycogenolytic effect of arginine vasotocin in liver pieces from the axolotl, ambystoma mexicanum, cultured in vitro.	in organ cultures of liver tissue from the axolotl, ambystoma mexicanum, 1 nmol/l arginine vasotocin (avt) increased tissue cyclic amp (camp) concentration, activated glycogen phosphorylase, and caused glycogen breakdown and glucose release. addition of 10 nmol/l insulin had no effect on any of these parameters. addition of glucagon together with avt caused a further increase in tissue camp but not in glucose release. ten nanomoles per liter of insulin added to the cultures 5 min before 1 nmol/l ...	1993	7681019
afferent and efferent connections of the thalamic eminence in the axolotl, ambystoma mexicanum.	afferent and efferent connections of the thalamic eminence of the axolotl were determined using the fluorescent compound dii as a tracer. the thalamic eminence is connected reciprocally with a number of telencephalic and diencephalic areas, particularly with the medial pallium, the amygdala and the preoptic region. efferent connections are widespread throughout the ipsilateral diencephalon. these findings are discussed in relation to the homology of this nucleus, especially its homologue in agna ...	1993	8474688
mesoderm differentiation in early amphibian embryos depends on the animal cap.	embryos of ambystoma mexicanum from the late morula to the late blastula stage were dissected and cultivated in varying combinations. the marginal zone (presumptive mesoderm) when isolated together with the vegetal region differentiated to notochord after dissection from early blastulae, but did not differentiate to other tissues. when isolated from middle to late blastulae, in addition myoblasts and mesenchyme were formed. the marginal zone isolated together with the animal region (presumptive ...	1993	28305977
isolation of cdnas for two closely related members of the axolotl wnt family, awnt-5a and awnt-5b, and analysis of their expression during development.	to characterize molecular interactions between cells in the early amphibian embryo, we have isolated cdnas for two members of the axolotl (ambystoma mexicanum) wnt family, awnt-5a and awnt-5b. the encoded proteins share 83% amino acid identity. using a reverse transcription-polymerase chain reaction (rt-pcr) assay, we find that awnt-5a transcripts are abundant in the blastula until gastrulation, barely detectable during gastrulation, and increase again during neurulation. they are detected throu ...	1993	8443107
affinophoresis as a test of axolotl accessory limbs.		1993	8302896
development and regeneration of limbs in the short toes axolotl mutant.		1993	8302894
analysis of the mutant axolotl short toes.		1993	8302893
fluorescent dye (dii) reveals the sensory cells in the lingual epithelium: a confocal laser scanning microscopic study.	fluorescent carbocyanine dye was applied to the glossopharyngeal nerve of axolotls fixed with paraformaldehyde. three cell types in the lingual epithelium were transneuronally labeled: chemosensory taste receptor cells and presumably mechanosensory basal cells in the taste buds, and epithelial cells with unknown function in the non-taste lingual epithelium.	1993	8271492
retinoic acid treatment inhibits mitosis in the pre-existing spinal cord during tail regeneration of the axolotl larva, ambystoma mexicanum.	during tail regeneration in the axolotl larva, ambystoma mexicanum, retinoic acid reduced mitosis some 10-fold in the pre-existing spinal cord. this conclusion followed from comparisons of mitotic indices in the central grey matter of spinal cords, proximal to the amputation plane, of animals intracoelomically injected with (a) retinoic acid 2 days before amputation and the mitotic inhibitor, demecolcine 5 h before sacrifice; or (b) as for the latter but without retinoic acid; or (c) only the so ...	1993	8243113
stage-dependent effects of retinoic acid on the regenerating limbs of larval korean salamander, hynobius leechii, at two amputation levels.	the morphological and biochemical data obtained in this series of experiments clearly confirm the previous finding about the relationship between the stage of limb regeneration and the effects of ra on duplication, i.e., the most sensitive stage for ra-induced duplication is the stage of dedifferentiation, regardless of the level of amputation. however, when the ra effects were expressed as a function of time after amputation, the upper arm regenerates clearly showed a prolonged and delayed resp ...	1993	8115390
asymmetric effects of retinoic acid on pattern formation in the transverse axes of regenerating axolotl limbs: test of a hypothesis.		1993	8115389
rna from normal anterior endoderm/mesoderm-conditioned medium stimulates myofibrillogenesis in developing mutant axolotl hearts.	in the axolotl, ambystoma mexicanum, a recessive cardiac lethal mutation causes an incomplete differentiation of the myocardium. mutant hearts do not contain sarcomeric myofibrils nor do they beat. we have previously shown that normal anterior endoderm, medium conditioned by endoderm, or total rna extracted from endoderm stimulates differentiation of mutant hearts in culture as indicated by the presence of organized myofibrils and rhythmic contractions of the "rescued" mutant heart tube. in this ...	1993	7516783
expression of a p0-like glycoprotein in central nervous system myelin of amphibians (ambystoma mexicanus, xenopus laevis and rana catesbeiana).	1. the myelin protein profiles in the cns and pns of three species of amphibians were analyzed by biochemical and immunohistochemical methods. 2. the cns myelin of the african clawed frog (xenopus) and the mexican salamander (axolotl) contained, in addition to proteolipid protein, a unique protein zero (p0)-like protein, whereas the adult bullfrog did not. 3. a strong expression of the p0-like protein in the bullfrog cns myelin was found transiently at ontogenetically early phases including at t ...	1993	7507810
amphibian micronucleus test(s): a simple and reliable method for evaluating in vivo genotoxic effects of freshwater pollutants and radiations. initial assessment.	a micronucleus test was developed using larvae from two urodele amphibians (pleurodeles waltl and ambystoma mexicanum) and an anuran (xenopus laevis). the methods for maintenance of adults, egg laying, and rearing the larvae are described, and the conditions required for optimal response are given for each of these species. the tests are carried out during a period of intense erythropoiesis when red blood cells are actively dividing in circulating blood. the micronuclei are observed on blood sme ...	1993	7688100
production and characterization of polyclonal antibodies against awnt-1, the axolotl homologue of the proto-oncogene product wnt-1.	the proto-oncogene wnt-1 (int-1) is activated by mouse mammary tumor virus retroviral insertion and contributes to the formation of mammary gland tumors in mice. during early development, it is expressed in small groups of cells in the developing central nervous system of fish, amphibians and mice. in the ambystoma mexicanum (axolotl) embryo, the expression profile of wnt-1 is biphasic. we have raised polyclonal antibodies against a synthetic peptide corresponding to a surface-exposed epitope of ...	1993	7691335