Publications

phylogeny of immunoglobulin heavy chain isotypes: structure of the constant region of ambystoma mexicanum upsilon chain deduced from cdna sequence.	an rna polymerase chain reaction strategy was used to amplify and clone a cdna segment encoding for the complete constant part of the axolotl igy heavy (c upsilon) chain. c upsilon is 433 amino acids long and organized into four domains (c upsilon 1-c upsilon 4); each has the typical internal disulfide bond and invariant tryptophane residues. axolotl c upsilon is most closely related to xenopus c upsilon (40% identical amino acid residues) and c upsilon 1 shares 46.4% amino acid residues among t ...	1993	8344718
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
conserved structure of amphibian t-cell antigen receptor beta chain.	all jawed vertebrates possess well-differentiated thymuses and elicit t-cell-like cell-mediated responses; however, no surface t-cell receptor (tcr) molecules or tcr genes have been identified in ectothermic vertebrate species. here we describe cdna clones from an amphibian species, ambystoma mexicanum (the mexican axolotl), that have sequences highly homologous to the avian and mammalian tcr beta chains. the cloned amphibian beta chain variable region (v beta) shares most of the structural char ...	1993	8341702
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
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
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
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
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
proteolytic cleavage of acth in corticotropes of sexually mature axolotls (ambystoma mexicanum).	immunohistochemical analysis of the pituitary of sexually mature axolotls revealed both acth(1-39)-related and alpha-msh-related immunoreactivity present in corticotropic cells located in the rostral anterior pituitary. gel filtration analysis indicated that the acth(1-39)-sized immunoreactivity and the alpha-msh-sized immunoreactivity detected in acid extracts of the axolotl anterior pituitary were present in a ratio in a range between 1:1 and 1:0.6. reversed-phase hplc analyses indicated that ...	2007	8284252
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
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
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
hormone-induced rise in cytosolic ca2+ in axolotl hepatocytes: extracellular origin and control by camp.	in amphibian liver, signal transduction of [arg8]vasotocin (avt), a "classical" ca(2+)-dependent hormone in rat liver, is mediated via the generation of adenosine 3',5'-cyclic monophosphate (camp) and not via inositol 1,4,5-trisphosphate [ins(1,4,5)p3]. in isolated hepatocytes from axolotl, hormones that stimulated camp formation (the order of efficacy was glucagon > isoprenaline > epinephrine > or = avt) also provoked a pronounced increase in cytosolic ca2+, as indicated from changes in fura 2 ...	1993	8238480
receptors for atrial natriuretic factor (anf) in kidney and adrenal tissue of urodeles--lack of angiotensin ii (a ii) receptors in these tissues.	binding sites for atrial natriuretic factor (anf) and angiotensin ii (a ii) were localized and quantified in renal and adrenal tissue of the urodele ambystoma mexicanum by quantitative in vitro autoradiography using 125i-ratanf(99-126) and 125i-[val5]-a ii or 125i-human a ii as labeled ligands. specific 125i-ratanf(99-126) binding was present in glomeruli, renal tubules, and adrenal tissue. anf had heterogeneous binding sites exhibiting positive cooperativity with a half maximal binding concentr ...	1993	8224766
characterization of a multimeric polypeptide complex on the surface of thymus-derived cells in the mexican axolotl.	we previously raised a rabbit antiserum (l12) against a 38 kd polypeptide which is expressed on the surface of thymocytes and peripheral t cells of an urodele amphibian, the mexican axolotl (ambystoma mexicanum). here we show that l12 antibodies immunoprecipitate several labelled molecules from surface iodinated axolotl spleen cells, including the 38 kd molecule, but also two polypeptides of 43 and 22 kd which are covalently linked to other elements. another rabbit antiserum (l10) was raised aga ...	1993	8211000
furrowing surface contraction wave coincident with primary neural induction in amphibian embryos.	we predicted, and have now observed, a surface contraction wave in axolotl (ambystoma mexicanum) embryos that appears to coincide temporally and spatially with primary neural induction and homoiogenetic induction, and with involution of the chordomesoderm. the wave starts from a focus anterior to the dorsal lip of the blastopore and spreads as an ellipse, until part of it encounters the rim of the blastopore and vanishes there. the remaining arc then continues over the dorsal hemisphere until it ...	1994	8158657
retinoic acid gradients during limb regeneration.	retinoids have been implicated in pattern formation processes in both developing chick limbs and in the regenerating limbs of urodele amphibians as well as in other aspects of embryonic development. since chick wing buds have been shown to have a higher concentration of all-trans-retinoic acid (ra) in the posterior region than in the anterior region, we set out to look for a gradient of ra in the regenerating limb of the axolotl, ambystoma mexicanum. we used high-performance liquid chromatograph ...	1994	8150219
phototaxic behavior and the retinotectal transport of horseradish peroxidase (hrp) in surgically created cyclopean salamander larvae (ambystoma).	negative phototaxis (np) was used to evaluate the recovery of vision in albino axolotl larvae with one eye discarded and the other transplanted either to the orbit (orthoclops) or to the top of the head (cyclops). np was assessed at approximately 1, 2 and 3 months postoperatively, using an automated, infrared monitor. some 88% of the orthoclopes and 64% of the cyclopes recovered np. however, among the cyclopes that did recover, the quantitative aspects of np were virtually the same as those of t ...	1993	8134018
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
spinal cord neuron classes in embryos of the smooth newt triturus vulgaris: a horseradish peroxidase and immunocytochemical study.	spinal cord neurons were investigated in embryos of triturus vulgaris, the smooth newt, just prior to hatching. these embryos can swim if freed from their egg membranes. horseradish peroxidase (hrp) labelling, together with gaba and glycine immunocytochemistry (icc), revealed nine distinct anatomical classes of neuron. 1. ventrolateral motoneurons with mainly dorsal dendrites, sometimes a descending central axon and peripheral axon innervating the trunk muscles. 2. dorsal primary sensory rohon-b ...	1993	8099742
plasma potassium may protect sodium pumps of toad hearts from an endogenous inhibitor.	resibufogenin (3-hydroxy-14,15-epoxy-20,22-dienolide glycoside) is a potent sodium pump inhibitor present in toad toxin. it is present in the skin of the cane toad (bufo marinus) at a concentration equivalent to ouabain of approximately 1 mm. because toads, like other amphibians, have permeable skin, resibufogenin is also found in high concentrations in the blood. in the cane toad the blood concentration is estimated to be 1 microm (d. lichtstein, s. kachalsky, and j. deutsch. life sci. 38: 1261 ...	1994	8092319
growth factor modulation of injury-reactive ependymal cell proliferation and migration.	injury-reactive ependymal cells from regenerating axolotl spinal cord can be maintained in their mesenchymal outgrowth phase in culture (o'hara et al., 1992). to address the ability of specific growth factors in stimulating or maintaining migration and proliferation, mesenchymal ependymal cell cultures derived from injured axolotl spinal cord at 2 weeks post-lesioning were used to determine the potential effects of epidermal growth factor, platelet-derived growth factor and transforming growth f ...	1994	8091423
electrophysiological and behavioral studies of taste discrimination in the axolotl (ambystoma mexicanum).	electrophysiological and behavioral experiments were performed to determine whether the taste system of the aquatic salamander, axolotl, discriminates taste stimuli. taste responses were recorded extracellularly from the glossopharyngeal nerve bundle. the behavioral responses of axolotls towards various concentrations of nacl, kcl, citric acid, quinine-hydrochloride, and sucrose were quantified by measuring the ratio of rejection towards gel pellets, each containing either unitary stimuli or bin ...	1994	8084890
pituitary-thyroid axis controls the final differentiation of the dorsal skeletal muscle in urodelan amphibians.	a histoenzymological study of the atpase activity of myosin in the dorsal axis muscle (dorsalis trunci) was carried out on two species of urodelan amphibians: pleurodeles waltlii, a euthyroid species with spontaneous metamorphosis and ambystoma mexicanum, a neotenic hypothyroid species. p. waltlii and a. mexicanum underwent an operation after which cytological analysis of the remaining pituitary were carried out in parallel. the muscle phenotype of urodelan amphibians varies according to the thy ...	1994	8074999
molecular cloning, sequencing and expression of an isoform of cardiac alpha-tropomyosin from the mexican axolotl (ambystoma mexicanum).	the cdna for alpha-tropomyosin (tm) was cloned by the polymerase chain reaction (pcr) from a lambda gt11 library constructed with mrna from juvenile axolotl heart tissues. subsequently, the nucleotide sequence of the cdna was determined. this is the first reported cdna for axolotl alpha-tropomyosin. comparative analyses of the deduced amino acid sequence of this cdna with xenopus skeletal muscle alpha-tropomyosin sequences indicate that the axolotl heart cdna has 93% and 96% homology in the regi ...	1994	8074673
morphology and infectivity of cultivated trypanosoma ambystomae.	cultures of trypanosoma ambystomae were initiated and maintained in hypo-osmotic biphasic blood-agar medium. epimastigotes and trypomastigotes occurred in culture and although they were similar in size, epimastigotes predominated with about 70% of all stages. epimastigotes divided by equal binary fission and occasionally formed rosettes. cultured trypomastigotes did not divide. cultures isolated 118 days earlier were infective to all 3 laboratory-reared ambystoma jeffersonianum and to 2 of 3 amb ...	1994	8064518
[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
multiple embryonic origins of gonadotropin-releasing hormone (gnrh) immunoreactive neurons.	experiments were conducted to test the hypothesis that gonadotropin-releasing hormone immunoreactive (gnrh-ir) and fmrfamide-ir neurons present in the brain and nervus terminalis originate in the embryonic olfactory placode. the olfactory placodes were bilaterally extirpated in stage 26 or stage 29 embryos of the axolotl, ambystoma mexicanum, which were then reared for 4-8 months before they were examined immunohistochemically. in experimental subjects with bilateral loss of olfactory epithelia, ...	1994	8026083
development of lateral line organs in the axolotl.	lateral line sensory receptors and their cranial nerves in axolotls arise from a dorsolateral series of placodes, including the octaval placode, that gives rise to the inner ear and the octaval nerve. anterodorsal and anteroventral placodes occur rostral to the octaval placode and give rise to anterodorsal and anteroventral lateral line nerves and electroreceptors and mechanoreceptors of the snout, cheek, and lower jaw. middle, supratemporal, and posterior placodes occur caudal to the octaval pl ...	1994	8006214
mitogen-activated axolotl (ambystoma mexicanum) splenocytes produce a cytokine that promotes growth of homologous lymphoblasts.	culture supernatants (pha-sns) from axolotl splenocytes cultured with phytohemagglutinin-p (pha) in medium supplemented with bovine serum albumin (bsa) were collected after 1, 2, and 3 days, pooled, treated to remove residual pha, precipitated with saturated ammonium sulfate, dialyzed, aliquoted, and stored at -20 degrees c. pha-sns stimulated proliferation of homologous lymphoblasts, but not resting splenocytes. sds-page of metabolically labeled pha-sns revealed a band between 14 and 21 kda. th ...	1994	8001702
cloning and expression of the axolotl proto-oncogene ski.	in vitro and in vivo overexpression studies have demonstrated that the c-ski proto-oncogene can influence proliferation, morphological transformation and myogenic differentiation. we report the isolation and expression of an axolotl (ambystoma mexicanum) c-ski (aski) gene. sequence analysis revealed a high degree of nucleotide and predicted amino acid (aa) homology with mammalian and anuran c-ski, showing the highest conservation to xenopus laevis c-ski (74% nucleotide and 87% aa). northern anal ...	1995	7999783
evolutionary conservation and molecular cloning of the recombinase activating gene 1.	a 700-bp fragment of the recombinase activating gene 1 (rag-1) was cloned from several evolutionarily distant (sandbar shark, paddlefish, goldfish, axolotl and pig) species using pcr. the nucleotide and deduced amino acid sequences revealed a highly conserved region that has remained essentially unaltered during 400 million years of evolution; e.g., shark and human sequences were 75% identical at the nucleic acid level and 87% as protein. the rag-1 mrna levels in the shark were analyzed using se ...	1994	7999099
heart specification in the mexican axolotl (ambystoma mexicanum).	the concept of the morphogenetic field has been used extensively in developmental biology. however, little is known about the mechanisms that partition these broad areas of tissue into the smaller areas which actually form the corresponding structures, and the remaining tissue. in the mexican axolotl, the heart field forms as the anterior lateral plate mesoderm migrates over the underlying pharyngeal endoderm between stages 14 and 28. we have previously shown that both the mid-ventral and latera ...	1994	7994078
organization of the serotoninergic system in the brain of two amphibian species, ambystoma mexicanum (urodela) and typhlonectes compressicauda (gymnophiona).	an immunocytochemical investigation was made of the distribution of serotonin (5-ht) in the brain of larval and adult ambystoma mexicanum and adult typhlonectes compressicauda. immunoreactive perikarya can be identified in the caudal diencephalon (paraventricular organ and infundibular nucleus), in the ventral mesencephalon (interpeduncular nucleus) and in the raphe of the rhombencephalon. immunopositive fibers and terminal arborizations are widely distributed, extending from the whole telenceph ...	1994	7985815
immunofluorescent studies on titin and myosin in developing hearts of normal and cardiac mutant axolotls.	homozygous recessive cardiac mutant gene c in the axolotl, ambystoma mexicanum, results in a failure of the embryonic heart to initiate beating. previous studies show that mutant axolotl hearts fail to form sarcomeric myofibrils even though hearts from their normal siblings exhibit organized myofibrils beginning at stage 34-35. in the present study, the proteins titin and myosin are studied using normal (+/+) axolotl embryonic hearts at stages 26-35. additionally, titin is examined in normal (+/ ...	1994	7966344
evolution of t cell receptor genes. extensive diversity of v beta families in the mexican axolotl.	we have cloned 36 different rearranged variable regions (v beta) genes encoding the beta-chain of the t cell receptor in an amphibian species, ambystoma mexicanum (the mexican axolotl). eleven different v beta segments were identified, which can be classified into 9 families on the basis of a minimum of 75% nucleotide identity. all the cloned v beta segments have the canonical features of known mammalian and avian v beta, including conserved residues cys23, trp34, arg69, tyr90, and cys92. there ...	1994	7963525
anatomy and forebrain projections of the olfactory and vomeronasal organs in axolotls (ambystoma mexicanum).	we examined the anatomy of the nasal cavity and forebrain in the axolotl (ambystoma mexicanum) to determine whether the olfactory and vomeronasal systems are present in this neotenic aquatic salamander. the current study was motivated by two considerations: (a) little is known of the anatomy of the vomeronasal system in aquatic vertebrates, and (b) the presence of both olfactory and vomeronasal systems in larval amphibians has broad implications for the evaluation of these systems in vertebrates ...	1994	7953608
computations of post-inductive dynamics in axolotl heart formation.	this paper reports modelling of heart localization in the axolotl (ambystoma mexicanum). the region of heart specification in the mesoderm defined by classical induction from the endoderm is larger than the area of final myocardial differentiation. for localizing the area of differentiation within the area of specification, we postulate a reaction-diffusion system that arises within the mesoderm in response to induction from the endoderm. this mechanism generates a spatial pattern for two chemic ...	1994	7949371
evidence for nmda receptor in the afferent synaptic transmission of the vestibular system.	this study aimed to define the pharmacology and physiological role of the n-methyl-d-aspartate (nmda) receptor in the synapse between the hair cells and primary afferent neurons in the vestibular system. the spontaneous and mechanically evoked spike discharges of vestibular nerve fibers were extracellularly recorded in isolated inner ear from the axolotl (ambystoma tigrinum). pressure ejection of nmda (10(-6) to 10(-3) m) elicited a dose-dependent increase of the basal spike discharge from the v ...	1994	7907935
[characterization of cdna of t-cell receptor beta chain in rainbow trout].	using a two-step pcr strategy, we have cloned several cdna segments encoding the t-cell receptor beta chain in a teleost fish, the rainbow trout (oncorhynchus mykiss). the nine clones analyzed encode identical n-terminal-truncated v beta regions which present limited sequence similarities with several mammalian tcr v beta chains, from residue tyr-35 to residue ser-95. these v beta regions are followed by v beta-d beta-j beta-like regions which are different in all the sequenced clones, and by id ...	1994	7882160
structure of the major neutral oligosaccharide-alditols released from the egg jelly coats of axolotl maculatum. characterization of the carbohydrate sequence galnac(beta 1-4)[fuc(alpha 1-3)] glcnac(beta 1-3/6).	several o-linked oligosaccharides of the jelly coat surrounding the eggs of axolotl maculatum were analysed by 1h-nmr spectroscopy. the four major oligosaccharidealditols released by reductive beta-elimination display either the lewisx (lex) determinant or the sequence galnac(beta 1-4)[fuc(alpha 1-3)]glcnac. this last structure has previously been characterized in allergenically active oligosaccharides isolated from the sea squirt h-antigen, and in the n-linked glycans of schistosoma mansoni and ...	1994	7881174
the third component of xenopus complement: cdna cloning, structural and functional analysis, and evidence for an alternate c3 transcript.	although the third component of complement has been purified from two amphibian species, xenopus laevis and the axolotl, only limited information is available about its primary structure in these species. we now present (a) 95% of the cdna sequence encoding c3 from a xenopus laevis/xenopus gilli (xenopus lg) hybrid (b) an analysis of the c3 convertase and factor i cleavage sites in xenopus c3, and (c) evidence for an alternative form of c3. the xenopus lg sequence has a 57% nucleotide and 52% am ...	1995	7875221
nmda-mediated potentiation of the afferent synapse in the inner ear.	in an isolated vestibular organ preparation from the axolotl (ambystoma tigrinum), glycine (10-0.01 microm) perfusion had no effect in the resting control condition, but significantly modified the response of afferent fibres to mechanical stimuli, producing a slowly increasing discharge rate during sinusoidal mechanical stimulation periods. this action was dependent upon the stimulus duration and was antagonized by 7-chloro-kynurenic acid (7-clkyn), 2-amino-5-phosphonopentanoic acid (ap5), n-all ...	1994	7841385
expression of the axolotl homologue of mouse chaperonin t-complex protein-1 during early development.	molecular chaperones assist in the folding of proteins, but their role during development is not well understood. here we report the temporal and spatial expression pattern of the axolotl homologue of mouse chaperonin tcp-1 during normal amphibian embryogenesis and in several models of abnormal embryogenesis. a partial axolotl tcp-1 cdna (646 bp; 519 coding bp) isolated by 3' race pcr shows considerable homology to mouse tcp-1. developmental northerns and rt-pcr analyses of whole axolot1 embryos ...	1995	7841192
activities of acetylcholinesterase, choline acetyltransferase, and catecholamine production in the spinal cord of the axolotl ambystoma mexicanum during forelimb regeneration.	amputation of an axolotl limb causes severance of the brachial nerves, followed by their regeneration into a blastema. it is known that these nerves provide a neurotrophic factor to blastemal cells. to approach the problem of the response of spinal cord nerve centers to forelimb amputation, we have studied biosynthetic activities in the nerve centers involved in axonal injury during limb regeneration. we report that the acetylcholinesterase (ache) activity in the spinal cord is elevated 2 days ( ...	2013	7840938
the evolution of efferent vagal control of the heart in vertebrates.	in vertebrates vagal preganglionic neurons are found in two principle locations in the brain-stem, the dorsal vagal motor nucleus and areas lateral to the dorsal vagal motor nucleus centered on the nucleus ambiguus. in elasmobranch fish 8% of vagal preganglionic neurons are located outside the dorsal vagal motor nucleus; these are all cardiac vagal motoneurones. this proportion increases from fish through amphibians to mammals in which over 30% of vagal preganglionic neurons are outside the dors ...	1994	7827254
ultrastructure of merkel-like cells labeled with carbocyanine dye in the non-taste lingual epithelium of the axolotl.	fluorescent carbocyanine dye (dii), applied to the glossopharyngeal (ix) nerve of the axolotl, transneuronally labeled solitary cells in the non-taste lingual epithelium. with diaminobenzidine (dab), the dii was photoconverted to a dark, electron-dense product. the labeled cell had a large nucleus with invaginations, dense-cored vesicles in the cytoplasm, and finger-like processes. these are reminiscent of morphological features of cutaneous merkel cells, suggesting that solitary cells innervate ...	1994	7816314
developmental regulation of a matrix metalloproteinase during regeneration of axolotl appendages.	removal of specific extracellular matrix (ecm) components has been implicated in the initiation of salamander limb regeneration. remodeling of the ecm at the distal stump is necessary for the release of cells that eventually contribute to the blastema. several matrix metalloproteinases (mmps) have been well characterized as important to various physiological and pathological processes, such as bone remodeling and tumor invasion. the goal of this study is to identify and characterize mmps that mo ...	1994	7813787
regulation of interrenal secretion in the axolotl, ambystoma mexicanum.	the regulation of corticosteroid secretion of the adrenal cortex (interrenal tissue) of axolotl (ambystoma mexicanum) was studied using in vitro preparations of kidney containing interrenal tissue. normally, 0.3-0.65 ng/5 min corticosterone and 0.15-0.3 ng/5 min aldosterone were released from the tissue. regulatory peptides were effective in the following range: acth = arginine vasotocin > urotensin ii > angiotensin ii. they stimulate an elevation of corticosterone (plus 0.2-1 ng/5 min) and of a ...	1994	7813601
the identification and partial cloning by pcr of the gene for tyrosinase-related protein-1 in the mexican axolotl.	the tyrosinase gene family is currently composed of three members, tyrosinase and two tyrosinase-related proteins, trp-1 and trp-2. these three gene products have all been found to act in the synthesis of melanin pigments with the enzyme tyrosinase catalyzing the initial rate-limiting steps. thus far these genes have primarily been analyzed in higher vertebrates. we have used degenerate pcr primers to isolate a large fragment of an axolotl tyrosinase-related protein. sequence analysis of the ent ...	1995	7792254
effect of induced metamorphosis on the immune system of the axolotl, ambystoma mexicanum.	metamorphosis was induced in neotenic axolotls by immersion of the animals in a solution of thyroid hormone. hematology of the axolotls was examined before, during, and after metamorphosis. there was a transient decrease in numbers of certain white blood cells during metamorphic climax and a permanent shift in the pattern of circulating cells. the eosinophilic granulocyte was the dominating leukocyte type in neotenes and in metamorphosing animals up to midclimax. lymphocytes and neutrophilic gra ...	1995	7789746
immunofluorescent confocal analysis of tropomyosin in developing hearts of normal and cardiac mutant axolotls, ambystoma mexicanum.	tropomyosin is a major component of the thin filaments in organized myofibrils of cardiac muscle cells. a purported role for this protein is to prevent myosin thick filaments from interacting with actin thin filaments until the cell contracts. recently, tropomyosin has been implicated in actin filament formation/stabilization as well. in the cardiac mutant axolotl, ambystoma mexicanum, heart development is arrested. mutant embryos form hearts that fail to beat due to a lack of organized sarcomer ...	1994	7779690
expression of pax-6 during urodele eye development and lens regeneration.	regeneration of eye tissues, such as lens, seen in some urodeles involves dedifferentiation of the dorsal pigmented epithelium and subsequent differentiation to lens cells. such spatial regulation implies possible action of genes known to be specific for particular cell lineages and/or axis. hox genes have been the best examples of genes for such actions. we have, therefore, investigated the possibility that such genes are expressed during lens regeneration in the newt. the pax-6 gene (a gene th ...	1995	7761453
effects of melanocyte-stimulating hormone on wild-type and white axolotl neural crest cells.	the goals of the current research were twofold: to study the effects of melanocyte-stimulating hormone (msh) on undifferentiated axolotl (ambystoma mexicanum) neural crest cells and to determine whether wild-type or white mutant axolotl neural crest cells respond differently to msh or to either of two agonists of the msh signal transduction pathway (cholera toxin or n6,o2-dibutyryl adenosine 3',5'-monophosphate (dbcamp). we found that msh induces melanophore differentiation in axolotl neural cre ...	1995	7755596
embryonic origin of amphibian taste buds.	despite numerous descriptive studies, the embryonic origin of vertebrate taste buds has never been experimentally determined. a number of different alternatives have been suggested for taste bud origins, including epibranchial placodes, the neural crest, and the local epithelium of the oropharyngeal cavity. the role of a series of epibranchial placodes and the cephalic neural crest, which together give rise to the cranial nerves innervating taste buds, was examined with regard to the development ...	1995	7750643
three-dimensional gradients of voltage during development of the nervous system as invisible coordinates for the establishment of embryonic pattern.	we are interested in the generation of endogenous electric fields associated with ionic currents driven through the vertebrate embryo by the transepithelial potential of its surface ectoderm. using a non-invasive vibrating electrode for the measurement of ionic current, we have provided measurements of currents traversing amphibian embryos, and a preliminary report of the internal, extracellular voltage gradient under the neural plate which polarizes the embryo in the rostral/caudal axis (metcal ...	1995	7734729
electroreceptors and mechanosensory lateral line organs arise from single placodes in axolotls.	the lateral line system in salamanders consists of mechanoreceptive neuromasts and pit organs, distributed in lines on the head and trunk, and electroreceptive ampullary organs located adjacent to the cephalic lines of mechanoreceptors. although numerous studies have documented that neuromast and pit organs and the cranial nerves that innervate these receptors arise from a dorsolateral series of placodes, there is no agreement concerning the number of these placodes, the specific groups of recep ...	1995	7729575
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
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
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
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
protein synthesis and release by normal and lesioned axolotl peripheral nerves.	previous studies in urodeles (holder et al., 1982, j. physiol. 326:371; holder et al., 1984, proc. r. soc. lond. b 222:477; aaronson et al., 1995, neuroscience 66:201) have shown that regenerating axons of peripheral nerves tend to grow toward distal nerve stumps, which is consistent with the hypothesis that axonal growth may be stimulated by factors released from degenerating nerves. in the present study we used two-dimensional gel electrophoresis and autoradiography to compare the incorporatio ...	1995	7672042
confrontation of developing melanophore bars of dark and white axolotls with endogenous dark-embryo mannose-binding lectin correlates with melanophore bar disruption.	lectins are carbohydrate-binding proteins suggested to be important in embryonic cell adhesion/differentiation. dark and white axolotls contain an endogenous mannose-binding lectin that is especially prevalent during larval melanophore pattern formation (martha et al., 1990). to determine if this lectin can alter melanophore patterning, lectin extracts have been isolated from dark embryos by affinity chromatography. the main protein band is 44k on sds-page. dark and white embryos at the early ch ...	1995	7659679
cloning, sequencing and expression of an isoform of cardiac c-protein from the mexican axolotl (ambystoma mexicanum).	c-protein, a myosin binding protein, is thought to regulate and stabilize thick filaments during assembly of sarcomeric a-bands. multiple isoforms of c-protein have been characterized in avian and mammalian systems. we now report the isolation and the nucleic acid sequence of a partial c-protein cdna clone from an axolotl heart cdna expression library in lambda gt11. the clone was isolated by screening the library with a heterologous monoclonal anti-c-protein antibody (mf1). sequence comparison ...	1995	7639739
oriented growth of regenerating axons in axolotl forelimbs is consistent with guidance by diffusible factors from distal nerve stumps.	previous studies have shown that when peripheral nerves in axolotl limbs are cut and surgically misdirected, regenerating axons grow back to the original pathways and innervate their correct muscles. in the present study however, we demonstrate that when given a choice between their correct nerve stump and an incorrect stump (forearm flexor nerve), regenerating extensor cranialis nerve axons grow towards both pathways. this result suggests that the directed growth of regenerating axons in the pe ...	1995	7637870
development of branchiomeric and lateral line nerves in the axolotl.	the differentiation of neural crest and ectodermal placodes was examined in the axolotl in order to clarify the contribution of these tissues to the formation of the sensory ganglia of the branchiomeric and lateral line cranial nerves in salamanders. the most rostral branchiomeric nerves, the profundal and trigeminal nerves, appear to arise solely from an ectodermal placode and from neural crest, respectively. the sensory ganglia of the more caudal branchiomeric nerves--the facial, glossopharyng ...	1995	7636024
erratic deposition of agrin during the formation of xenopus neuromuscular junctions in culture.	in order to disclose the mechanism that regulate synapse development we compared the distributions of agrin, acetylcholine receptors (achr) and a basal lamina heparan sulfate proteoglycan (hspg) in sections and cultures prepared from xenopus laevis and ambystoma mexicanum embryos. while agrin, achr and hspg may accumulate almost synchronously at synapses in vivo, agrin deposition usually lagged well behind the other synaptic markers during development in culture, and was not detectable at many d ...	1995	7601300
regulation of hoxa expression in developing and regenerating axolotl limbs.	homeobox genes are important in the regulation of outgrowth and pattern formation during limb development. it is likely that homeobox genes play an equally important role during limb regeneration. we have isolated and identified 17 different homeobox-containing genes expressed by cells of regenerating axolotl limbs. of these, nearly half of the clones represent genes belonging to the hoxa complex, which are thought to be involved in pattern formation along the proximal-distal limb axis. in this ...	1995	7600989
the role of vertical and planar signals during the early steps of neural induction.	the classical einsteck-test (spemann and mangold, roux arch. dev. biol. 100: 599-638, 1924) and data from total exogastrulae (holtfreter, 1933) suggest that vertical signals are transmitted between the chordamesoderm (organizer) and reacting ectoderm in the early phase of neural induction. in contrast to these results with axoloti (urodeles), several authors observed the expression of neural specific genes in xenopus exogastrulae, isolated dorsal blastopore lip with adjacent ectoderm (open-face ...	1995	7577445
a "minimal essential mhc" and an "unrecognized mhc": two extremes in selection for polymorphism.	the high polymorphism of classical mhc molecules found in mammals is not simply the result of strong selection for pathogen resistance in the recent past, since there are virtually no examples of diseases caused by infectious pathogens for which resistance is determined by particular mhc haplotypes, and in the best-studied case, a particular aspect of malaria in humans, the selection is remarkably weak. we discuss three possibilities to explain high polymorphism in mammals: accumulating, merging ...	1995	7558083
identification and expression of a homologue of the murine hoxa5 gene in the mexican axolotl (ambystoma mexicanum).	an excellent model for studying heart development in vertebrates is the cardiac non-function lethal mutant (gene c) mexican axolotl, ambystoma mexicanum. in order to facilitate our analyses of the mutant system, we have undertaken a search for stage-specific molecular markers during embryonic development of the axolotl. we have concentrated on homeobox genes as suitable candidates for monitoring molecular changes during development. a 270-bp probe encoding a portion of the axolotl homeobox gene ...	1995	7557438
tissue boundaries and cell behavior during neurulation.	we have analyzed the dynamics of the boundaries between the neural plate and the epidermis and between the neural plate and the notoplate. our experiments confirm that these two boundaries have important roles in neurulation. measurements of the lengths of neural fold (the boundary between epidermis and neural plate) in embryos of axolotls and newts reveal that neural folds abutting the prospective brain decrease in length while neural folds abutting the prospective spinal cord increase in lengt ...	1995	7556911
noradrenergic and peptidergic innervation of the amphibian spleen: comparative studies.	spleens from representatives of the three amphibian orders were examined using sucrose-potassium phosphate-glyoxylic acid (spg) histofluorescence to detect catecholamines and immunocytochemistry to detect several neural antigens. nerve fibers are scattered throughout the spleens of adult salamanders (taricha torosa, notophthalmus viridescens, and ambystoma mexicanum). a less abundant but similarly diffuse pattern of innervation characterizes the spleen of the caecilian, typhlonectes sp. the sple ...	1994	7539385
neuroepithelial endocrine and nervous system in the respiratory tract of cynops pyrrhogaster with special reference to the distribution of nitric oxide synthase and serotonin.	the respiratory tract of urodeles harbours an intramural nerve network comprising an innervated system of neuroepithelial endocrine (nee) cells. however, striking differences have been noted between phylogenetically closely related species. zamboni- or formaldehyde-fixed whole-mount preparations and sections of the saclike lungs of a japanese salamander, cynops salamander, cynops pyrrhogaster, have been investigated for the immunocytochemical detection of nitric oxide synthase (nos), serotonin ( ...	1994	7529073
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
characterization of immunoglobulin heavy chain variable regions in the mexican axolotl.		1994	7506234
uncoupling histogenesis from morphogenesis in the vertebrate embryo by collapse of the transneural tube potential.	we have shown that unidirectional pumping of na+ out of the neural tube's luminal fluids in amphibian embryos produces a large potential difference (40-90 mv, lumen negative to the abluminal surface). this transneural tube potential (tntp) is analogous to the na+ dependent transepithelial potential (tep) that exists across surface ectoderm. this tep is retained in ectoderm after it is internalized when the neural folds fuse to form the neural tube. the tntp can be markedly reduced for several ho ...	1995	7496037
segmental innervation of rotated and supernumerary axolotl hindlimbs.	the segmental nerve supply to axolotl limbs was misrouted by severing the limbs at the level of the femur, rotating them 180 degrees around their long axis, and then suturing them to the intact proximal stump. following return of the blood supply to the rotated limb by the cross-anastomosing of blood vessels, a blastema often formed to the side of the rotation site giving rise to a supernumerary limb. the muscles of both rotated and supernumerary limbs were innervated by the segmental nerves. th ...	1980	7462973
dominant lethal induction by ethyl methanesulfonate in the male axolotl (ambystoma mexicanum).	when male axolotls (ambystoma mexicanum) were treated with ethyl methanesulfonate (ems) and mated at regular intervals thereafter, the incidence of embryonic abnormalities among the f1 progeny increased until a time was reached when none survived to hatching. at 100 mg/1 ems, this point was reached about 130 days after treatment. thereafter, the frequency of abnormalities gradually decreased to control levels. at higher concentrations, abnormalities were seen in spawnings obtained sooner after t ...	1980	7462966
neural crest replaced by gastrula ectoderm in amphibia. effect on neurulation, cns, gills and limbs.	early axolotl gastrula ectoderm was grafted into early triturus neural stages in place of excised neural folds at the gill and anterior trunk level. macroscopically the young graft behaves like normal neural fold material: it follows the closing host neural plate to the dorsal midline, folds into the host's interior and, especially in the gill region, moves ventrad beneath the host's epidermis. these movements cannot be interpreted as active migration. they are the result of passive displacement ...	1980	7457916
evidence of the first genetic activity required in axolotl development.		1980	7444204
regions of the brain influencing the projection of developing optic tracts in the salamander.	eye primordia from the mexican axolotl or the california newt were transplanted into hosts of either species. these "third" eyes often developed an optic nerve that penetrated the host brain and made one of three central projections: bilateral to the dorsal thalami, tecta, and basal optic nuclei; ipsilateral to the same areas; or ipsilateral into the cord. the type of projection made by a transplanted eye seemed to depend on where its nerve first entered the brain. the optic fibers that reached ...	1980	7440804
the effects of eliminating impulse activity on the development of the retinotectal projection in salamanders.	the california newt taricha torosa manufactures tetrodotoxin, a blocker of voltage-sensitive sodium channels and therefore of action potentials.the newt's own nervous system is insensitive to this toxin. grafting an embryonic eye to the newt from a tetrodotoxin-sensitive species, the mexican axolotl, blocks action potentials in the retinal ganglion cells of the transplanted eye. neuroanatomical and electrophysical techniques demonstrate that while such ganglion cells are incapable of firing impu ...	1980	7440803
regulation and potency in the forelimb rudiment of the axolotl embryo.	anterior, posterior, dorsal and ventral halves of the pre-bud forelimb rudiment of tail-bud axolotl embryos can all give rise to normal limbs after the complementary half has been removed. a histological study of the regulation of the posterior half rudiment showed no requirement for mesodermal healing across the gap, and no proliferative zone. the development of the limb bud on the operated side lags behind that of the control bud for several weeks of larval life. when half limb rudiments and d ...	1980	7430930
experiments on developing limb buds of the axolotl ambystoma mexicanum.	various experiments were performed on the limb buds of axolotls to compare the behaviour of amphibian limbs with that previously reported for chick limbs. following removal of the tip or whole limb bud, extensive powers of regulation were observed since complete limbs always formed. similarly after distal to proximal grafts intercalary regulation occurred to produce perfect limbs and after proximal to distal grafts serial repetitions resulted. transplantation and rotation of limb buds to reverse ...	1980	7430928
gap junctions in early amphibian embryos.	cell pairs from late cleavage and early blastula ambystoma mexicanum embryos were found to be electrotonically coupled. thin-section electron microscopy revealed typical gap junctions between the cells. freeze-fracture electron microscopy showed the gap junctions to be comprised of aggregations of 8.5-nm p-face particles and corresponding e-face pits. the conductance of the amphibian embryonic gap junction is known to be voltage-dependent, but no obvious gating structure was resolved by these mo ...	1980	7416050
ultrastructure of the renal juxtaglomerular complex and peripolar cells in the axolotl (ambystoma mexicanum) and toad (bufo marinus).	renal juxtaglomerular regions were examined in the axolotl (ambystoma mexicanum and toad (bufo marinus). prominent granulated peripolar epithelial cells were found surrounding the origin of the glomerular tuft in the axolotl. these cells resembled the peripolar cells recently discovered in mammalian species. they contained multiple electron-dense cytoplasmic granules, some of which showed a paracrystalline substructure and signs of exocytoxic activity. such cells were difficult to find and small ...	1980	7410189
regeneration of reversed aneurogenic arms of the axolotl.	aneurogenic arms of young axolotls were implanted into the flank as heterotopic autografts with reversed proximo-distal orientation. the formerly proximal ends of such arms regressed to a variable extent, and then either regenerated or could do so following a second amputation. the regenerate always contained a complete sequence of skeletal elements between the adjacent stump skeleton and terminal digits, being a mirror image of the implanted arms with identical transverse axes but an opposed pr ...	1980	7400749
an interaction between dorsal and ventral regions of the marginal zone in early amphibian embryos.	when small explants from early gastrulae of xenopus laevis are allowed to develop in a buffered salt solution there is a considerable difference between the patterns of differentiation obtained from different dorsoventral levels of the marginal zone. these patterns of differentiation correspond to the fates of the different regions in the course of normal development. they are not altered if several explants of the same type are fused before culture. if a ventral marginal zone explant from xenop ...	1980	7400747
electrical activity in cardiac mutant axolotl hearts.	electrical recordings from the hearts of both cardiac lethal mutant and normal embryos showed the presence of action potentials conducted over the heart tube. ionic coupling and gap junctions also were observed in both. these results suggest that the absence of heart function in mutant embryos does not result from a defect in electrical activity.	1980	7373269
spatial distribution of abundant proteins in oocytes and fertilized eggs of the mexican axolotl (ambystoma mexicanum).		1980	7372013
neural crest cell migration in relation to extracellular matrix organization in the embryonic axolotl trunk.		1980	7371990
distal transformation from double-half forearms in the axolotl, ambystoma mexicanum.		1980	7371978
regeneration of symmetrical forelimbs in the axolotl, ambystoma mexicanum.		1980	7371977
melanogenesis in oocytes of wild-type and mutant albino axolotls.		1980	7371975