Publications
| Title | Abstract | Year Filter | PMID(sorted descending) Filter |
|---|
| a molecular marker for cell guidance information in the axolotl embryo. | previous studies from this laboratory suggested that the elongation of the pronephric duct (pnd) in the axolotl ambystoma mexicanum is directed by an adhesion gradient along the migrating cells' substratum. we have also shown that cranial neural crest (cnc) cells are able to follow the pnd guidance information, for which these cells serve as useful probes (s.l. zackson and m.s. steinberg, (1986) dev. biol. 117, 342-353). these experiments allow the construction of a map of the cell guidance info ... | 1988 | 3378673 |
| factors involved in the formation and stabilization of cell aggregates obtained from amphibian embryonic explants. | the effect of factors influencing the formation and stability of animal and vegetal aggregates from xenopus laevis and ambystoma mexicanum was examined in the light and scanning electron microscopes. at extreme values of ph the surface coat covering the vegetal aggregates is dissolved and dissociation may take place. animal aggregates are more resistant. at high tonicities vegetal aggregates may be dissociated, and in the animal aggregates the epidermal differentiation is suppressed. in the abse ... | 1988 | 3370680 |
| connections between the nucleus isthmi and the tectum in larval and post-metamorphic axolotls. | the nucleus isthmi (ni) is the primary relay for the frog's ipsilateral visuotectal projection. using electrophysiological methods, ipsilateral visuotectal activity has been recorded in thyroxine-treated, postmetamorphic axolotls but not in larval axolotls. in order to determine whether changes in isthmotectal projections are responsible for this change in electrophysiological responsiveness, we have investigated the connections between the tectum and the ni using horseradish peroxidase. our res ... | 1988 | 3351504 |
| a synapse-specific carbohydrate at the neuromuscular junction: association with both acetylcholinesterase and a glycolipid. | with the aim of investigating the roles of carbohydrates in synapse formation, we have characterized a synapse-specific saccharide at the vertebrate neuromuscular junction. two lectins of similar specificity (dolichos biflorus agglutinin, dba, and vicia villosa-b4 agglutinin, vva-b4) stain synaptic but not extrasynaptic regions of the rat muscle fiber surface and thus define a synapse-specific carbohydrate. using these and other probes, we show that the carbohydrate moiety concentrated at the ne ... | 1988 | 3346730 |
| superinnervation enhances the dendritic branching pattern of the mauthner cell in the developing axolotl. | mauthner cells (m-cells) occur as a pair of large, uniquely identifiable neurons at ear level in the hindbrain of premetamorphic amphibians. each receives synapses from the ipsilateral vestibular nerve (nviii); these morphologically distinctive terminals, or club endings, are confined to the proximoventral surface and branches of the m-cell lateral dendrite. we have superinnervated this portion of the m-cell to examine the extent to which forming afferent contacts regulate the growth and branchi ... | 1988 | 3346721 |
| progressive patterning precedes somite segmentation in the mexican axolotl (ambystoma mexicanum). | beginning at mid-neurulation, a wave of somite segmentation passes down the axolotl body axis in a cephalocaudal direction. at 20 degrees c a somite forms every 2.57 hr. fate-mapping of the presomitic mesoderm indicates that the primordia for the next few somites occupy nearly the same space that they will after segmentation, but that the remaining somites are densely packed in tip of the tail bud. brief heat shocks at 37 and 38.5 degrees c reveal that within the first of these two zones, there ... | 1988 | 3342928 |
| basal lamina is not a barrier to neural crest cell emigration: documentation by tem and by immunofluorescent and immunogold labelling. | one of the factors proposed to control initiation of migration of neural crest (nc) cells is disruption of the basal lamina (bl) that is presumed to exist over the dorsal portion of the neural tube. previously, we discovered that, in the mouse embryo, a continuous bl is not deposited over the dorsal portion of the neural tube until emigration of the nc cells is terminated. here, we show that the pattern of bl deposition in chick embryos is similar, but not identical, to that in the mouse. in par ... | 1987 | 3332260 |
| induction of micronuclei in peripheral erythrocytes of axolotl larvae following in vivo exposure to mutagenic agents. | previous work from this laboratory demonstrated the presence of micronuclei in erythrocytes from larvae of the urodele amphibian pleurodeles waltl reared in water containing clastogenic substances. in order to investigate the generality of this finding, larvae from another urodele ambystoma mexicanum (axolotl) were reared in water containing one of the two following compounds: benzo[a]pyrene (bap) or ethylmethane sulphonate (ems). the level of micronucleated erythrocytes on blood smears was comp ... | 1986 | 3331662 |
| detection of mutagenicity in drinking water using a micronucleus test in newt larvae (pleurodeles waltl). | we have previously described a micronucleus test using erythrocytes from larvae of the urodele amphibians pleurodeles waltl (pleurodele) and ambystoma mexicanum (axolotl). the test is based on a comparison of the levels of micronucleated erythrocytes in blood smears from larvae reared in water containing a clastogen, with the levels from larvae reared in purified water. using larvae from the pleurodele, we have employed this test to evaluate mutagenic activity in drinking water. groups of larvae ... | 1987 | 3325745 |
| use of retinoids to analyze the cellular basis of positional memory in regenerating amphibian limbs. | cells of the amphibian limb regeneration blastema inherit memories of their level of origin (positional memory) along the limb axes. these memories serve as boundaries of what is to be regenerated, thus preventing regeneration of any but the missing structures. because of its importance in determining the boundaries of regenerate pattern, it is essential to understand the cellular and molecular basis of positional memory. one approach to this problem is to look for position-related differences i ... | 1987 | 3325080 |
| the effect of replacing different regions of limb skin with head skin on regeneration in the axolotl. | head skin was used to replace different halves of limb skin from the upper and lower arms of axolotls. replacement of upper arm posterior skin caused the regeneration of a high proportion of single-digit limbs while replacement of dorsal, ventral or anterior skin caused only minor defects to the normal skeletal pattern. when dorsal or ventral skin was replaced, however, regenerates often lacked dorsal or ventral muscle. results from the lower arm were different in that replacement of any half of ... | 1986 | 3309120 |
| accessory limb production by nerve-induced cell proliferation. | the deviation of large limb nerves to a more proximal skin wound yielded a high proportion of accessory limb responses in different age groups of ambystoma mexicanum (axolotls). in some instances the deviated nerve was positioned on skin previously grafted from an animal of different age and pigmentation from that of the host. grafts were found not to be a necessary prerequisite for accessory limb induction, but the presence of wound epithelium was required. the rule of distal morphogenesis was ... | 1988 | 3291642 |
| injection of an antibody against a p21 c-ha-ras protein inhibits cleavage in axolotl eggs. | the presence of a ras protein was demonstrated in cleaving axolotl eggs by selective immunoprecipitation with a polyclonal antibody against a peptide encoded by the c-ha-ras oncogene, cellular homolog of the v-ha-ras oncogene of harvey rat sarcoma virus. injection of this antibody into axolotl oocytes subjected to progesterone treatment does not prevent meiotic maturation. injection of the same antibody into a blastomere of axolotl eggs at the 2- or 4-cell stage causes cleavage arrest in the des ... | 1988 | 3277177 |
| retinoic acid proximalizes level-specific properties responsible for intercalary regeneration in axolotl limbs. | the objective of this study was to determine whether retinoic acid (ra) coordinately proximalizes positional memory and the cellular recognition system that detects pattern discontinuity in regenerating amphibian limbs. the strategy was to test the capacity of ra-treated blastemas to evoke intercalary regeneration when grafted to an amputation level proximal to their level of origin. control wrist and ankle, or elbow and knee blastemas treated with the retinoid solvent, dimethylsulphoxide, evoke ... | 1988 | 3268411 |
| a rapid method for observing the internal morphology of amphibian embryos. | a simple, rapid method for visualizing the internal morphology of amphibian embryos is described. fixed embryos of ambystoma mexicanum are surrounded with commercial embedding material and are frozen. internal structure is revealed by cutting the embryos with a cooled scalpel or razor blade, removing the frozen embedment with an aqueous buffer, and processing the halved embryos for scanning electron microscopy (sem). this technique allows the internal anatomy of the embryo to be viewed but is mu ... | 1988 | 3238382 |
| characterization of an igy-like low molecular weight immunoglobulin class in the mexican axolotl. | the general thinking about the phylogenic distribution of vertebrate ig classes is that fish and urodele amphibians are only able to synthesize polymeric igm-like molecules and that the emergence of a new class of lmw ig occurs for the first time in anouran species. following immunization of the mexican axolotl (ambystoma mexicanum, amphibia, urodela) with tnp-srbc, hmw anti-tnp antibody molecules are only detected. we have previously shown that these polymeric ig are constituted of 76 kda h-cha ... | 1988 | 3237220 |
| [radioautographic and electron microscopic research on the structure and dynamic proliferative activity of muscle satellite cells during limb muscle transplantation in axolotls]. | 2015 | 3231405 | |
| reformation of specific neuromuscular connections during axolotl limb regeneration: evidence that the first contacts are correct. | retrograde neuronal tracing with horseradish peroxidase was used to determine the position in the spinal cord of the motor neurone pools of a proximal (biceps) and a distal (extensor digitorum) limb muscle at various times during axolotl limb regeneration. it was found that from the earliest stages of muscle redifferentiation (as judged by light and electron microscopic analysis) the vast majority of axons innervating the regenerating muscles came from cells within the bounds of the normal motor ... | 1988 | 3224559 |
| a quantitative analysis of glial cell coupling in the retina of the axolotl (ambystoma mexicanum). | the strength of gap junctional coupling of radial glial cells (müller cells) in the isolated axolotl retina was assessed by monitoring the spread of dye between cells, and by injecting current into one cell and recording the voltage response in surrounding cells. dye injected into one müller cell spread to surrounding müller cells, and could be detected up to 130 micron away, i.e. over 4 times the mean müller cell spacing of 30 micron. injecting 1 na of current into a müller cell evoked response ... | 1988 | 3224259 |
| myocardial cell relationships during morphogenesis in normal and cardiac lethal mutant axolotls, ambystoma mexicanum. | sarcomere formation has been shown to be deficient in the myocardium of axolotl embryos homozygous for the recessive cardiac lethal gene c. we examined the developing hearts of normal and cardiac mutant embryos from tailbud stage 33 to posthatching stage 43 by scanning electron microscopy in order to determine whether that deficiency has any effect on heart morphogenesis. specifically, we investigated the relationships of myocardial cells during the formation of the heart tube (stage 33), the in ... | 1988 | 3213830 |
| hypersensitivity to light of the iris (sphincter pupillae) of the albino axolotl (ambystoma mexicanum). | as is common for amphibians, the sphincter pupillae of the axolotl contracts in vitro in response to illumination with visible light. 1. in a comparison of photomechanical responses of albino and normally pigmented axolotls, similar time courses and maxima of force development were found. 2. the dependence of isometric active force development on the length of the sphincter pupillae is similar to that of other smooth muscles. 3. the action spectrum of the axolotl is similar to the absorption spe ... | 1988 | 3209975 |
| the organization of the cardiac ganglion of the axolotl (ambystoma mexicanum). | the heart of the axolotl ambystoma mexicanum was studied with histochemical methods to determine the distribution of neurons containing acetylcholine esterase, catecholamines and 5-hydroxytryptamine. the cardiac ganglion is made up of cholinergic nerve fibers and somata, and of catecholaminergic fibers. small intensely fluorescent cells were found along blood vessels in the pericardial wall at the base of the heart, but not in the heart itself, except, in a few instances, in the region bordering ... | 1988 | 3209798 |
| the location of cues promoting selective reinnervation of axolotl muscles. | the selective reinnervation of muscles suggests that muscles have intrinsic recognition cues that promote selective synaptogenesis. for example, the anterior and posterior heads of the axolotl iliotibialis (ilt) muscle are preferentially reinnervated by their original motoneurons even after surgically exchanging them. the nature and location of cues that promote such selectivity are unknown, although previous work suggests that the muscle fibers themselves might harbor the relevant molecules. to ... | 1988 | 3171683 |
| retinoic acid coordinately proximalizes regenerate pattern and blastema differential affinity in axolotl limbs. | an assay that detects position-related differences in affinity of axolotl regeneration blastema cells in vivo was used to test whether retinoic acid, which proximalizes regenerate pattern, simultaneously proximalizes blastema cell affinity. the assay involved autografting or homografting late bud forelimb blastomas derived from the wrist, elbow or midupper arm levels to the dorsal surface of the blastema-stump junction of an ipsilateral, medium-bud-stage hindlimb regenerating from the midthigh l ... | 2011 | 3168786 |
| identification of pigment cells during early amphibian development (triturus alpestris, ambystoma mexicanum). | the purpose of the present investigation was to provide and apply a methodological manual with which the distribution, patterning and relationship of melanophores and xanthophores can be analyzed during early amphibian development. for demonstration of the methods, which include ultrastructural, histochemical and biochemical approaches, triturus alpestris and ambystoma mexicanum (axolotl) embryos are used. these two species differ conspicuously in their larval pigment patterns, showing alternati ... | 1988 | 3141059 |
| monoclonal antibodies to axolotl immunoglobulins specific for different heavy chains isotypes expressed by independent lymphocyte subpopulations. | an immunoblotting analysis of purified axolotl immunoglobulins (ig) separated by sds-page reveals two heavy (h) chains isotypes: a 76 kda chain recognized by the monoclonal antibody (mab) 33.45.1 and a 66-68 kda doublet recognized by the mab 33.39.2. the 76 kda chain is associated to high molecular weight (hmw) ig molecules and the 66-68 kda h chains are associated to low molecular weight (lmw) ig of 172 kda. both h chains isotypes are linked to identical light (l) chains, labelled in immunoblot ... | 1988 | 3136082 |
| thyroxine and triiodothyronine in plasma and thyroids of the neotenic and metamorphosed axolotl ambystoma mexicanum: influence of trh injections. | circulating levels of t3 and t4, as well as t3 and t4 content of the thyroid glands were measured by radioimmunoassay in the neotenic and metamorphosed axolotl ambystoma mexicanum. in the two experiments which were performed plasma t4 concentrations were more elevated in metamorphosed axolotls, especially in the first experiment (2.12 +/- 0.40 ng/ml vs. 369 +/- 30 pg/ml). t3 plasma values which were only estimated in the second experiment were about five times higher in metamorphosed animals (63 ... | 1988 | 3131185 |
| surface markers of axolotl lymphocytes as defined by monoclonal antibodies. | in an attempt to identify urodele amphibian lymphocyte subpopulations by their surface markers, we prepared hybridomas from balb/c mice spleen immunized with axolotl (ambystoma mexicanum) blood and splenic leucocytes and purified immunoglobulins. sixty-five hybridomas were selected and subsequently subcloned. among numerous monoclonal antibodies (mabs) thus obtained, four mabs were extensively characterized by immunoblotting, single and double fluorescence and immunohistology. mab 34.38.6 recogn ... | 1988 | 3127327 |
| membrane currents in retinal bipolar cells of the axolotl. | by whole-cell patch-clamping bipolar cells isolated from enzymatically dissociated retinae, we have studied the nonsynaptic ionic currents that may play a role in shaping the bipolar cell light response and in determining the level of voltage noise in these cells. between -30 and -70 mv, the membrane current of isolated bipolar cells is time independent, and the input resistance is 1-2 g omega. depolarization past -30 mv activates an outward current (in less than 100 ms), which then inactivates ... | 1988 | 3125305 |
| paraboloid of axolotl retinal photoreceptor and bovine pituitary thyrotropin fraction share an antigen. | lenses of newts (genera notophthalmus, triturus, cynops) regenerate from irises in the presence of retinae of larval frogs (rana) or adult salamanders (hynobius, ambystoma), species which are themselves incapable of lens regeneration from the iris. in newts, bovine pituitary thyrotropin preparation nih-tsh-b8 can also stimulate lens regeneration from the iris. an antiserum against nih-tsh-b7 (purified as is nih-tsh-b8), absorbed with bovine lutropin preparation nih-lh-b9, cross-reacts with bovin ... | 1988 | 3121378 |
| antibody diversity in amphibians. noninbred axolotls used the same unique heavy chain and a limited number of light chains for their anti-2,4-dinitrophenyl antibody responses. | noninbred axolotls (ambystoma mexicanum, amphibia, urodela) were immunized with trinitrophenylated sheep red blood cells (tnp-srbc) and anti-2,4-dinitrophenyl (dnp)/tnp antibodies were individually purified by affinity chromatography. the isolated igm-like antibodies were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (sds-page) and isoelectric focusing (ief) under reducing conditions. the sds-page and ief-separated heavy (h) and light (l) chains were electroblotted onto n ... | 1987 | 3106061 |
| [structural characteristics and innervation of chromaffin tissue in the adrenal gland of the axolotl]. | each adrenal gland of the axolotl consists of a strip lying all along the medio-lateral edge on the ventral surface of the kidney. the gland is composed of interrenal cells (ic) and chromaffin cells (cc). the ic contained a great number of pleomorphic lipid droplets, smooth endoplasmic reticulum and elongated mitochondria with tubulo-vesicular cristae. two types of cc, always disposed in clusters and exhibiting long cytoplasmic processes were described according to the electron density, size and ... | 1986 | 3094843 |
| promotion of chromatophore differentiation in isolated premigratory neural crest cells by extracellular matrix material explanted on microcarriers. | this study was undertaken to determine whether premigratory neural crest cells of the axolotl embryo differentiate autonomously into chromatophores, or whether stimuli from the environment, particularly from the extracellular matrix, are required for this process. neural crest cells were excised from the dorsal part of the premigratory crest cord and cultured alone, either in a serum-free salt solution or in the presence of fetal calf serum (fcs), and together with explants of the neural tube or ... | 2010 | 3081390 |
| differential cytolocalization of prosomes in axolotl during oogenesis and meiotic maturation. | the prosomes, a novel type of small rna-protein complex previously characterized in avian and mammalian cells, were isolated from axolotl (ambystoma mexicanum) oocytes and identified by sedimentation analysis and protein composition. the prosomal nature of these particles was further ascertained by immunoblot analysis with anti-duck prosome monoclonal antibodies. by in vitro [35s]methionine labelling, de novo synthesis of prosomal proteins could be detected neither during oogenesis nor meiotic m ... | 1988 | 3075616 |
| luteinizing hormone-releasing hormone induces thyroxine release together with testosterone in the neotenic axolotl ambystoma mexicanum. | in male neotenic axolotls ambystoma mexicanum plasma concentrations of thyroxine (t4) and testosterone were increased following intravenous injection of 10 micrograms luteinizing hormone-releasing hormone. a dose of 50 micrograms influenced only plasma t4 levels. this observation suggests for the first time that a hypothalamic hormone is capable of stimulating the thyroidal axis in the neotenic axolotl. | 1988 | 3056776 |
| actions of excitatory amino acid acid agonists and antagonists on the primary afferents of the vestibular system of the axolotl (ambystoma mexicanum). | in order to determine the nature of the transmitter in the synapse between hair cells and primary afferent fibers, both resting and evoked spike activity of vestibular system afferents were recorded. excitatory amino acid agonists and antagonists were applied by micro perfusion. excitatory amino acid agonists consistently increased the firing rate of these afferents. the rank order in potencies of the agonists tested was: kainate greater than or equal to quisqualate greater than d-aspartate grea ... | 1988 | 3052698 |
| retinoic acid-binding protein in the axolotl: distribution in mature tissues and time of appearance during limb regeneration. | analysis of cytoplasmic protein preparations from axolotl tissues revealed the presence of a cytoplasmic retinoic acid-binding protein (crabp), of approximate molecular weight 17k. this protein was found to be present at various concentrations in skin, muscle, and limb tissue preparations, but not in liver and serum preparations. the distribution and molecular weight of this protein agrees with that reported in mammalian studies. the level of crabp in cone stage blastemas was found to be signifi ... | 1986 | 3019799 |
| cyclic amp and cell differentiation in amphibian embryonic explants. | conflicting results have been published concerning the effects of cyclic nucleotides on amphibian cell differentiation. here we report the effects of cyclic adenosine monophosphate (camp) and dibutyryl-cyclic adenosine monophosphate (db-camp) on isolated explants from late blastulae of ambystoma mexicanum and xenopus laevis. both camp and db-camp (10(-4)-10(-9) m) promote 'neuralizing' differentiation in ambystoma explants. xenopus explants treated with the nucleotides (10(-4), 10(-6), 10(-8) m) ... | 1986 | 3011532 |
| [hormonal determination of the differentiation of striated skeletal muscle in urodele amphibians]. | in the urodelan amphibian pleurodeles waltlii, spontaneous external metamorphosis was correlated with an increase in the serum level of thyroxine (t4). within the same period, a change occurred in the myofibrillar atpase profile of the dorsal skeletal muscle; fibres of larval type were gradually replaced by transitional fibres (type iic), then by adult fibres of the types i, iia, and iib. likewise, a myosin isoenzymic transition was observed. in larval animals, myosin electrophoresis revealed 3 ... | 1988 | 2973102 |
| hormone action in newt limb regeneration: insulin and endorphins. | although several hormones have been linked to newt limb regeneration, a cohesive hypothesis as to how these hormones control the process is yet to emerge. a critical review of the traditional approaches and a reevaluation of currently operative assumptions and interpretations of results precede the data on insulin and beta-endorphin. results from in vivo and in vitro experiments on insulin are summarized, showing that insulin not only promotes various cellular events but also is essential for th ... | 1987 | 2963650 |
| regulation by thyroid hormones of terminal differentiation in the skeletal dorsal muscle. ii. urodelan amphibians. | in the urodelan amphibian pleurodeles waltlii, spontaneous anatomical metamorphosis was correlated with an increase in the serum level of thyroxine (t4). it was also accompanied by a change in the myofibrillar atpase profile of the dorsal skeletal muscle; fibers of larval type were gradually replaced by the adult fiber types i, ii a, and ii b. likewise, a myosin isoenzymic transition was observed in dorsal muscle, larval isomyosins were replaced by adult isoforms. in a related species, ambystoma ... | 1987 | 2957262 |
| [in vitro development of blastema cells in axolotl limb regeneration: effect of insulin and nerve extracts on cellular proliferation]. | for the purpose of investigating the nature of the nervous factor which controls cell proliferation in limb blastema of newts, we have cultured primary mesenchymous cells from limb blastemas of axolotl. the cultures were carried out in petri dishes (primaria, falcon) with a basal medium with contained diluted mem supplemented with hormones (insulin, somatotropin, hydrocortisone and thyroxine). in this medium, the cells disperse from the explant from the 4th day of culture and begin to divide fro ... | 2010 | 2952210 |
| compatible limb patterning mechanisms in urodeles and anurans. | we have experimentally tested the similarity of limb pattern-forming mechanisms in urodeles and anurans. to determine whether the mechanisms of limb outgrowth are equivalent, we compared the results of two kinds of reciprocal limb bud grafts between xenopus and axolotls: contralateral grafts to confront anterior and posterior positions of graft and host, and ipsilateral grafts to align equivalent circumferential positions. axolotl limb buds grafted to xenopus hosts are immunologically rejected a ... | 1989 | 2912797 |
| timing in the regulation of neural crest cell migration: retarded "maturation" of regional extracellular matrix inhibits pigment cell migration in embryos of the white axolotl mutant. | in larvae of the white axolotl mutant (ambystoma mexicanum), contrary to normal dark ones, trunk pigmentation is restricted because the epidermis is unable to support subepidermal migration of pigment cells from the neural crest (nc). this study examines whether the subepidermal extracellular matrix (ecm) is the defective component which prevents pigment cell migration in the white embryo. we transplanted subepidermal ecm, adsorbed in vivo on membrane microcarriers, from and to white and dark em ... | 1989 | 2909402 |
| recovery of acetylcholinesterase activity after irreversible inhibition by organophosphorous compounds in embryonic development. | 1. recovery of acetylcholinesterase (ache) activity was studied using the embryos of sea urchins strongylocentrotus intermedius and s. nudus, embryos of axolotl ambystoma mexicanum and in the chick embryo muscle culture treated by "irreversible" organophosphorous inhibitors (opi). 2. ache activity was assayed by a modified ellman's procedure. 3. it follows from the data obtained that, unlike the plutei of sea urchins and the monolayer culture of chick embryo muscle cells, the embryos of axolotl ... | 1988 | 2898993 |
| electrogenic glutamate uptake is a major current carrier in the membrane of axolotl retinal glial cells. | glutamate is taken up avidly by glial cells in the central nervous system. glutamate uptake may terminate the transmitter action of glutamate released from neurons, and keep extracellular glutamate at concentrations below those which are neurotoxic. we report here that glutamate evokes a large inward current in retinal glial cells which have their membrane potential and intracellular ion concentrations controlled by the whole-cell patch-clamp technique. this current seems to be due to an electro ... | 2008 | 2885752 |
| immunocytochemical localization and spatial relation to the adenohypophysis of a somatostatin-like and a corticotropin-releasing factor-like peptide in the brain of four amphibian species. | the distribution of somatostatin (srif) - and corticotropin-releasing factor (crf)-like - immunoreactive material was studied in the brain of four amphibian species (ambystoma mexicanum, pleurodeles waltlii, xenopus laevis, rana ridibunda) by use of immunocytochemistry. a wide network of srif-immunoreactive fibers and numerous perikarya were observed in all amphibians examined, with a dense accumulation of nerve endings in the external layer of the median eminence (elme). in the representatives ... | 1987 | 2880668 |
| in vitro differentiation of neuronal precursor cells from amphibian late gastrulae; morphological, immunocytochemical studies, biosynthesis, accumulation and uptake of neurotransmitters. | neuronal differentiation has been studied in dissociated cell cultures from early neurulae of pleurodeles waltl and ambystoma mexicanum. cocultures were prepared from the neural primordium and underlying chordamesoderm. np and nf cultures were prepared from isolated neural plate and neural folds, respectively. neuronal precursors in np and nf cultures had distinctive aggregation properties already evident after 1-2 days in culture. after 10-15 days, mature neurones and synapses were observed by ... | 1985 | 2863321 |
| binding of adrenergic ligands to liver plasma membrane preparations from the axolotl, ambystoma mexicanum; the toad, xenopus laevis; and the australian lungfish, neoceratodus forsteri. | the beta-adrenergic ligand iodocyanopindolol (icp) bound specifically to hepatic plasma membrane preparations from the axolotl, ambystoma mexicanum (bmax, 40 fmol/mg protein (p) at free concentration above 140 pm; kd, 42 pm); the toad, xenopus laevis (bmax, 200 fmol/mg p at 1 nm; kd, 300 pm); and the australian lungfish, neoceratodus forsteri (bmax, 100 fmol/mg p at 5 nm). for the lungfish, the scatchard plot was curved showing two classes of binding site with kd's of 20 and 500 pm. neither the ... | 1988 | 2847957 |
| cellular retinoic acid binding protein: detection and quantitation in regenerating axolotl limbs. | the concentrations of apo (unoccupied), holo (occupied), and total cellular retinoic acid binding protein (crabp) were measured at various stages of axolotl limb regeneration. the ratio of apo-crabp to holo-crabp declined with advancing regenerate stage until the crabp was all in the holo form. the increase in holo-crabp is correlated with a stage-dependent shift in the effect of exogenous retinoic acid on regenerate pattern, from pattern duplication to inhibition of regeneration. the data sugge ... | 2010 | 2838564 |
| neuroepithelial endocrine cells in the lung of ambystoma mexicanum. | neuroepithelial endocrine (nee) cells were for the first time identified in the lung of the entirely aquatic urodele, ambystoma mexicanum, by using light and electron microscopy, histochemistry, and immunocytochemistry. in the basal part of the ciliated epithelium and, less often, in the respiratory portion of the lung, nee cells were found to occur both solitarily and in small clusters. no typical neuroepithelial bodies could be found. using the method of fernandez pascual, some nee cells were ... | 1989 | 2817428 |
| evidence for a change in expression of dna ligase genes in the pleurodeles waltlii germ line during gonadogenesis. | the expression of dna ligase genes was studied using the nuclear transplantation approach in the germ line of pleurodeles waltlii (p. waltlii) just before and during gonadogenesis. germ cell (gc) nuclei were isolated from larvae of p. waltlii and transplanted into unfertilized ambystoma mexicanum eggs. dna ligase activity in these eggs was then analyzed after sucrose gradient fractionation. the activity of dna ligase i (heavy form, 7.5 s) of p. waltlii was present when the transplanted gc nuclei ... | 2009 | 2776966 |
| drug-induced and genetic hypermelanism: effects on pigment cell differentiation. | allopurinol, a drug that inhibits the enzyme xanthine dehydrogenase (xdh), is known to cause hypermelanism in the axolotl. the hypermelanistic condition that results from allopurinol treatment is similar in most respects to the phenotype that results from the action of the melanoid (m) gene in axolotls. on the basis of structural and biochemical studies, it now seems clear that genetic and drug-induced hypermelanism are the same in the following ways. 1) both types of melanism result in the prod ... | 2016 | 2771877 |
| organization of positional information in the axolotl limb. | we have used the phenomenon of position-dependent growth stimulation, brought about by the confrontation of cells with dissimilar positional values, to reveal the organization of positional information in the center of the upper and lower arms of axolotls. when either humerus or radius was transplanted into either dorsal or posterior positions, extra growth leading to the formation of supernumerary digits occurred following amputation through the graft. however, transplants of humerus or radius ... | 2009 | 2769199 |
| the effect of eel calcitonin on calcium influx and plasma ion levels in axolotls, ambystoma mexicanum. | plasma total calcium and calcium influx, measured during 4-h 45ca influx experiments, were lower in control axolotls, ambystoma mexicanum, during august when compared to those in july. a single intraperitoneal injection of 10 micrograms of synthetic eel calcitonin significantly reduced the calcium influx rates during both months but the effect was greater in july (p less than 0.001) than in august (p less than 0.05). plasma levels of calcium, sodium, potassium, and magnesium were not affected. i ... | 1989 | 2767402 |
| ultrastructural localization of acetylcholinesterase in axolotl brain capillaries. | the ultrastructural distribution of cholinesterases on the brain capillaries of axolotl has been studied. the axolotl brain contains branching, anastomosing capillary network and capillary loops. the presence of acetylcholinesterases is seen on the basal lamina and in the spaces between the endothelial cells and the pericytes of both types of vessels. the role of this enzyme in the blood-brain barrier is discussed. | 1989 | 2756743 |
| electrosensory activity in the telencephalon of the axolotl. | electrical shock of the anterior lateral line nerve evokes slow wave potentials in the contralateral corpus striatum and bilaterally in the medial pallium of the telencephalon of axolotls. the onset latency of the evoked response in the medial pallium (70 ms) is considerably longer than that of the corpus striatum (46 ms). quasi-natural stimuli, such as weak uniform electric fields (100 microv/cm) or water drops striking the surface of the water surrounding the axolotls elicited evoked potential ... | 1989 | 2748022 |
| [origin of the cells in the symmetrical forelimbs of the axolotl ambystoma mexicanum]. | 2003 | 2740070 | |
| analysis of the endocardium and cardiac jelly in truncal development in the cardiac lethal mutant axolotl ambystoma mexicanum. | recessive mutant gene c in axolotls results in a failure of the heart to function because of abnormal embryonic induction processes. the myocardium in this mutant lacks organized sarcomeric myofibrils. the present study was undertaken to determine if developmental abnormalities were evident in other areas of the heart besides the myocardium. a detailed comparative survey of the structure of developing normal and mutant hearts, including the endocardium, its cellular derivatives, and the extracel ... | 1989 | 2724338 |
| lack of proliferative response in denervated, reamputated limb regenerates of larval ambystoma. | this paper describes the response of early four-digit regenerates of axolotls to reamputation and denervation. reamputation of innervated regenerates led to sharp increases in 3h-thymidine labeling index (li) and mitotic index (mi) on days 2-5 post-reamputation. this resembles the response of innervated limbs following initial amputation. regenerates that were denervated at the time of reamputation exhibited no proliferative response through day 5. this is in marked contrast to denervated, origi ... | 1989 | 2708951 |
| neural fold formation at newly created boundaries between neural plate and epidermis in the axolotl. | according to a recent model, the cortical tractor model, neural fold and neural crest formation occurs at the boundary between neural plate and epidermis because random cell movements become organized at this site. if this is correct, then a fold should form at any boundary between epidermis and neural plate. to test that proposition, we created new boundaries in axolotl embryos by juxtaposing pieces of neural plate and epidermis that would not normally participate in fold formation. these bound ... | 1989 | 2707486 |
| studies of heart development in normal and cardiac lethal mutant axolotls: a review. | the morphology of developing hearts in axolotls, ambystoma mexicanum, has been studied by scanning electron microscopy in order to provide a chronology of morphogenesis that can be correlated with ongoing biochemical and immunocytochemical studies. in addition to normal embryos we have studied homozygous recessive cardiac lethal mutant axolotls. the mutant myocardium undergoes aberrant sarcomere development and lacks a normal heartbeat. morphogenesis of mutant hearts appears to be nearly normal ... | 1989 | 2699076 |
| ontogeny of immunoglobulin expression in the mexican axolotl. | the ontogeny of immunoglobulin (ig) synthesis was followed at both cellular and serological levels in the mexican axolotl (ambystoma mexicanum) using polyclonal antibodies recognizing all ig molecules and a set of monoclonal antibodies (mabs) specific for the c mu and cv heavy ig chain isotypes and for the light chain constituents shared by igm and igy molecules. clusters of igm- and of igy-synthesizing lymphocytes, often located in separate sites, are first present in spleen sections of 7-week- ... | 2006 | 2698798 |
| immunofluorescent, immunogold, and electrophoretic studies for desmin in embryonic hearts of normal and cardiac mutant mexican axolotls, ambystoma mexicanum. | recessive mutant gene c for "cardiac nonfunction" in axolotls results in an absence of normal heart contractions in affected embryos due to a failure of myofibril formation. in the present study, the intermediate filament protein, desmin, is compared in developing normal and mutant hearts by means of two-dimensional gel electrophoresis, immunofluorescent microscopy, and immunoelectron microscopy. tissues were fixed in periodate-lysine-paraformaldehyde or paraformaldehyde-glutaraldehyde solutions ... | 2009 | 2681791 |
| analysis of actin and tropomyosin in hearts of cardiac mutant axolotls by two-dimensional gel electrophoresis, western blots, and immunofluorescent microscopy. | when homozygous, recessive mutant gene c in ambystoma mexicanum results in a failure of embryonic heart function. this failure is apparently due to abnormal inductive influences from the anterior endoderm resulting in an absence of normal sarcomeric myofibril formation. biochemical and immunofluorescent studies were undertaken to evaluate the contractile proteins actin and tropomyosin in normal and mutant hearts. for the immunofluorescent studies, cardiac tissues were fixed in periodate-lysine-p ... | 1989 | 2664186 |
| immunocytochemical localization and immunochemical characterization of an insulin-related peptide in the pancreas of the urodele amphibian, ambystoma mexicanum. | the pancreas of the axolotl, ambystoma mexicanum, was investigated by immunocytochemical methods for the presence of immunoreactivity to a number of antisera raised against mammalian insulins. all anti-insulin antisera tested revealed substantial amounts of reaction products confined solely to the aldehyde-fuchsinophilic b cells of the endocrine pancreas. the reactive cell population was detected by use of one polyclonal antiserum against bovine insulin and eight different monoclonal antibodies ... | 1989 | 2663173 |
| cellular morphogenesis and the formation of marginal bands in amphibian splenic erythroblasts. | the spleen of ambystoma mexicanum (axolotl) larvae develops as a closed sac containing differentiating nucleated erythrocytes, and is typically isolated from the general circulation for about 10 days post-hatching. beginning 3-4 days posthatching, it can be removed intact for examination of the morphology and cytoskeletal structure of the erythropoietic cells. in the smallest (earliest) spleens, spheroidal cells predominate, while older ones contain a preponderance of cells exhibiting the flatte ... | 1989 | 2653647 |
| amphibian (urodele) myotomes display transitory anterior/posterior and medial/lateral differentiation patterns. | myotome differentiation during mexican axolotl (ambystoma mexicanum) somitogenesis was analyzed by employing anti-actin and anti-myosin monoclonal antibodies as molecular probes. myotome differentiation occurs after segmentation and proceeds in the cranial-to-caudal direction along the somite file. within individual somites myotome differentiation displays distinct polarities. examination of the somite file at the tailbud stage revealed that soon after segmentation, actin/myosin accumulate predo ... | 1989 | 2647546 |
| spatial aspects of neural induction in xenopus laevis. | a monoclonal antibody, 2g9, has been identified and characterised as a marker of neural differentiation in xenopus. the epitope is present throughout the adult central nervous system and in peripheral nerves. staining is first detected in embryos at stage 21 in the thoracic region. by stage 29 it stains the whole central nervous system, except the tail tip. the epitope is present in a 65k mr protein, and includes sialic acid. the antibody also reacts with neural tissue in mice and axolotls and n ... | 1989 | 2632233 |
| fine structure of the epidermal leydig cells in the axolotl ambystoma mexicanum in relation to their function. | the fine structure of the leydig cells in the epidermis of the strictly aquatic adult axolotl ambystoma mexicanum resembles that of similar cells in larval salamanders. the major finding of this study is that the mucous secretion of the leydig cells is released into the intercellular spaces from which it is discharged through pores onto the surface of the epidermis where it forms a mucous layer to protect the skin. | 2009 | 2630544 |
| the appearance of neural and glial cell markers during early development of the nervous system in the amphibian embryo. | cell-type-specific antibodies have been used to follow the appearance of neurones and glia in the developing nervous system of the amphibian embryo. differentiated neurones were recognized with antibodies against neurofilament protein while glial cells were identified with antibodies against glial fibrillary acidic protein (gfap). the appearance of neurones containing the neurotransmitters 5-hydroxytryptamine and dopamine has been charted also. in xenopus, neurofilament protein in developing neu ... | 2008 | 2627893 |
| organization of connective tissue patterns by dermal fibroblasts in the regenerating axolotl limb. | a set of tendons, aponeurotic sheets and retinaculae, which transduce muscle action from proximal limb levels to flexion and extension of the digits, is found in limbs of many vertebrates. this set of structures, here termed the digit tendon complex, is described for the axolotl forelimb. we show that the complex forms autonomously in muscleless axolotl limb regenerates produced from a cuff of unirradiated dermis surrounding an irradiated limb stump, and persists for up to a year after amputatio ... | 1989 | 2612366 |
| evolution of motor patterns: aquatic feeding in salamanders and ray-finned fishes. | patterns of muscle activity (motor patterns) have generally been found to be strongly conserved during the evolution of aquatic feeding behavior within closely related groups of fishes and salamanders. we conducted a test of the generality of motor pattern conservation with a much broader phylogenetic scope than has been done previously. activity patterns of three cranial muscles were quantified from electromyographic (emg) recordings made during suction feeding in a salamander (ambystoma mexica ... | 1989 | 2611639 |
| cellular contribution to symmetrical forelimbs from triploid-marked "polarizing region" in the embryo of axolotl, ambystoma mexicanum. | grafts of posterior tissue placed anterior to the limb bud in the salamander embryo exert a polarizing influence. to explain this result, the idea that the anteroposterior axis of the developing forelimb is polarized by a diffusible morphogen has been proposed. an alternative hypothesis, and the working hypothesis of the present study, is that the polarization of the developing salamander forelimb is accomplished by short-range cellular interactions resulting in intercalation rather than by the ... | 1989 | 2600559 |
| regulatory peptides (glucagon, somatostatin, substance p, and vip) in the brain and gastrointestinal tract of ambystoma mexicanum. | the concentrations of immunoreactive components of glucagon, somatostatin, substance p, and vasoactive intestinal polypeptide (vip) in the brain, stomach, and gut of the neotenic mexican axolotl (ambystoma mexicanum) were determined by radioimmunoassay using antibodies of defined regional specificity. the molecular forms of the immunoreactive components were analyzed by high-performance liquid chromatography (hplc). the concentrations and molecular forms of somatostatin and vip in axolotl brain ... | 1985 | 2580753 |
| kinetics of light-sensitive channels in vertebrate photoreceptors. | we have studied the ion channels mediating the light response of vertebrate rod photoreceptors by analysing fluctuations in the current across the rod membrane, using the whole cell patch-clamp technique on rods isolated from the axolotl retina. light decreases the membrane current fluctuations. noise analysis reveals two components to this decrease: a low frequency component due to biochemical noise in the transduction mechanism, and a high frequency component we attribute to the random opening ... | 1985 | 2579400 |
| the role of retinoid-binding proteins in the generation of pattern in the developing limb, the regenerating limb and the nervous system. | we summarize existing data and describe new information on the levels and distribution of cellular retinoic acid-binding protein (crabp) and cellular retinol-binding protein (crbp) in the regenerating axolotl limb, the developing chick limb bud and the nervous system of the chick embryo in the light of the known morphogenetic effects of retinoids on these systems. in the regenerating limb, levels of crabp rise 3- to 4-fold during regeneration, peaking at the time when retinoic acid (ra) is most ... | 1989 | 2561479 |
| axolotl pronephric duct cell migration is sensitive to phosphatidylinositol-specific phospholipase c. | on the basis of its distribution pattern in embryos of the axolotl (ambystoma mexicanum), we recently identified alkaline phosphatase as a molecule potentially involved in guiding the migration of the pronephric duct. alkaline phosphatase is a cell surface protein anchored to cell membranes via a covalent linkage to a phosphatidylinositol glycan (pi-g). the enzyme phosphatidylinositol-specific phospholipase c (piplc) specifically releases from cell surfaces molecules anchored by the pi-g linkage ... | 1989 | 2553384 |
| the relationship among retinoid structure, affinity for retinoic acid-binding protein, and ability to respecify pattern in the regenerating axolotl limb. | to further our understanding of the action of retinoids on the respecification of pattern in the regenerating axolotl limb we have studied the relative potencies of a range of synthetic and natural retinoids administered locally to the blastema. alterations in the polar end group of the retinoic acid (ra) molecule to produce esters, the alcohol, or the aldehyde abolish the ability of the molecule to respecify pattern. on the other hand, alterations of the ring or side chain to produce the synthe ... | 1989 | 2537244 |
| immunohistochemical localization of beta-endorphin-like material in the urodele and anuran amphibian tissues. | in the present study, we have localized for the first time beta-endorphin (beta-ep)-like material in the adult and larval urodele and anuran tissues using immunohistochemical techniques. in the adult notophthalmus viridescens and ambystoma mexicanum, strong immunoreactivity to beta-ep antisera was observed in the region of the intermediate lobe, the latter fluorescing as a discrete body. the fluorescence was confined to the periphery of the cells, while the nuclei and the immediately surrounding ... | 1989 | 2530130 |
| biosynthesis of sulfated proteoglycans in amphibian embryonal cells. | the synthesis of sulfated proteoglycans in small explants from various parts of late blastulae from ambystoma mexicanum or xenopus laevis was investigated by incorporation of radioactive sulfate or glucosamine and galactosamine in media of low, normal or high tonicity. the explants differentiated into ciliated aggregates of fibroblast-like cells, or remained undifferentiated depending upon their origin in the embryo. high tonicity induces the explants to dissociate and prevents morphological dif ... | 1989 | 2504303 |
| [experimental teratomas from xenogenic embryonic implants in the urodele amphibian, pleurodeles waltlii michah]. | ambystoma mexicanum embryos in stages 5 to 32 were implanted into the coelomic cavity of larvae or metamorphosing larvae of pleurodeles waltlii. out of 76 experimental animals, 43 presented teratomas a few months later. in another series of experiments, ambystoma embryos together with pleurodeles embryos were implanted in 18 pleurodeles larvae. teratomas developed in 13 cases. considering the two series, tumors evolved slowly and remained benign in 31 animals, whereas in 25 others, the tumor gro ... | 1989 | 2499409 |
| homing behaviour of regenerating axons in the amphibian limb. | following peripheral nerve deviation in the limbs of urodele amphibians axons regrow distally toward their previous target muscles (holder et al. 1984; proc. roy. soc. lond. b 222, 477-489). this study describes analysis of this axon regeneration over time following deviation of the forearm flexor nerve in triturus cristatus and the extensor cranialis nerve in the axolotl. using horseradish peroxidase (hrp) axonal tracing, electrophysiology and electron microscopy, we describe the sequence of ev ... | 1989 | 2485244 |
| the distribution of fibronectin and tenascin along migratory pathways of the neural crest in the trunk of amphibian embryos. | it is generally assumed that in amphibian embryos neural crest cells migrate dorsally, where they form the mesenchyme of the dorsal fin, laterally (between somites and epidermis), where they give rise to pigment cells, and ventromedially (between somites and neural tube), where they form the elements of the peripheral nervous system. while there is agreement about the crest migratory routes in the axolotl (ambystoma mexicanum), different opinions exist about the lateral pathway in xenopus. we in ... | 1988 | 2470571 |
| diverse supernumerary structures develop after inverting the anteroposterior limb axis of the anuran. | contralateral limb bud graftings were performed on tadpoles of the anuran bufo bufo. the anteroposterior axis was inverted while the larvae were at stage iv or v (e.g., between 22-30 days after fertilization). eighty-four tadpoles were operated on, 10 of which were used as controls. at anterior or posterior location 104 supernumerary structures developed in toto. they were collected and whole-mount examined after being stained with alcian blue. they were further prepared for serial sectioning, m ... | 1989 | 2466718 |
| induction of mesodermal tissues by acidic and basic heparin binding growth factors. | the inducing activity of two heparin binding growth factors hbgf-1 (prostate epithelial cell growth factor; acidic pi) and hbgf-2 (fibroblast growth factor; basic pi) from bovine brain has been tested on totipotent ectoderm from early amphibian (xenopus laevis, ambystoma mexicanum) embryos. both factors induced, at high concentrations, mostly compact spheres surrounded by a non-epidermal epithelium. when the concentration or time of incubation was reduced, large muscle inductions frequently orga ... | 1988 | 2451566 |
| characterization of axolotl heavy and light immunoglobulin chains by monoclonal antibodies. | axolotl specific antibodies to 2,4-dinitrophenyl (dnp) were purified by affinity chromatography from the sera of animals immunized with 2,4,6-trinitrophenylated sheep red blood cells (tnp-srbc). the purified anti-tnp/dnp antibodies, when analyzed by sds-page, were constituted of high molecular weight molecules, which in reducing conditions, were separated into heavy 72-88 kd and light 27-30 kd polypeptides. the axolotl heavy antibody chains strongly bound concanavalin-a and migrate faster in sds ... | 1987 | 2449389 |
| increase of substance p-like immunoreactivity in the peripheral nerve of the axolotl after injury. | that substance p may be a neurotrophic factor in urodele limb regeneration was investigated in the axolotl (ambystoma mexicanum). two weeks after section of the peripheral nerves to the forelimb, there was a marked increase in substance p-like immunoreactivity (ir) content of the nerves proximal to the lesion. a smaller increase occurred as early as 3 days after section of nerves innervating a regrowing limb bud (blastema), and substance p-ir fibres were observed by immunocytochemistry to innerv ... | 1987 | 2447537 |
| bipolar cell membrane currents and signal processing in the axolotl retina. | 1987 | 2446219 | |
| neurotransmitter-induced currents in retinal bipolar cells of the axolotl, ambystoma mexicanum. | 1. whole-cell patch clamping was used to study the membrane properties of isolated bipolar cells and the currents evoked in them by putative retinal neurotransmitters. 2. isolated bipolar cells show an approximately ohmic response to voltage steps over most of the physiological response range, with an average input resistance of 1.3 g omega and resting potential of -35 mv. these values are underestimates because of the shunting effect of the seal between the patch electrode and the cell membrane ... | 1987 | 2443677 |
| induction of myofibrillogenesis in cardiac lethal mutant axolotl hearts rescued by rna derived from normal endoderm. | a strain of axolotl, ambystoma mexicanum, that carries the cardiac lethal or c gene presents an excellent model system in which to study inductive interactions during heart development. embryos homozygous for gene c contain hearts that fail to beat and do not form sarcomeric myofibrils even though muscle proteins are present. although they can survive for approximately three weeks, mutant embryos inevitably die due to lack of circulation. embryonic axolotl hearts can be maintained easily in orga ... | 1987 | 2443338 |
| a scanning electron microscopy and histological study on the effects of the mutant eyeless (e/e) gene upon the hypothalamus in the mexican axolotl ambystoma mexicanum shaw. | a scanning electron microscopy, histological, and immunochemical investigation examined the effects of the mutant gene (e) upon hypothalamic development in the mexican axolotl. the adult eyeless mutant is sterile. previous studies indicated that this reproductive defect was due to the mutation's effect upon the hypothalamus. the present study demonstrated the pleiotropic effects of the eyeless gene upon development of the hypothalamus. scanning electron microscopy studies looked at the early ont ... | 1986 | 2426993 |
| a model of inward and outward membrane currents in cultured embryonic amphibian spinal neurons and reconstruction of the action potential. | a model of the membrane currents in embryonic amphibian neurons has been developed in order to investigate the ionic mechanisms underlying developmental changes in excitability. differentiating amphibian neurons both in situ and in vitro show a gradual change in the ionic sensitivity of their action potential from ca- to na-dependent, with an intermediate period in which the action potential shows a mixed ionic sensitivity. the model developed incorporates quantitative descriptions of na, ca and ... | 1985 | 2422357 |
| glucagon and insulin regulate in vitro hepatic glycogenolysis in the axolotl ambystoma mexicanum via changes in tissue cyclic amp concentration. | glucagon increases the rate of glycogenolysis in in vitro cultures of hepatic tissue from the axolotl ambystoma mexicanum. the hormone causes an increase in the concentration of cyclic amp in the tissue which is followed by activation of glycogen phosphorylase and subsequent breakdown of glycogen and release of glucose from the tissue. insulin counteracts the glycogenolytic effect of glucagon by inhibiting the increase in tissue cyclic amp concentration brought about by glucagon. this inhibitory ... | 1986 | 2416634 |
| embryonic induction and cation concentrations in amphibian embryos. | explanted ectoderm from early gastrulae of triturus alpestris was treated with the na-k ionophore gramicidin (10(-9) to 10(-5) m) and the ca-ionophore a 23187 (10(-7) to 10(-5) m). the ectoderm developed almost exclusively to atypical epidermis as in the control explants. when the ectoderm was treated with ouabain (10(-4) m), intracellular na+ increased about 4.4-fold and k+ was reduced by half. mesenchyme cells in small number differentiated in about 40% of the ouabain-treated explants. the tim ... | 1985 | 2416476 |
| normal fates and states of specification of different regions in the axolotl gastrula. | a fate map was constructed for four regions of the early gastrula of ambystoma mexicanum using orthotopic grafts from donors labelled with fldx (fluoresceinated-lysinated-dextran). the region around the animal pole gave rise to epidermis only and did not include prospective neural plate. the dorsal marginal zone contributed to cephalic endoderm and to the whole length of the axial mesoderm (notochord and somites), the lateral marginal zone to lateroventral and somitic mesoderm, and the ventral m ... | 1985 | 2411838 |
| motorneuron pools innervating muscles in vitamin a-induced proximal-distal duplicate limbs in the axolotl. | serially duplicated limbs containing two sets of proximal muscles were created in axolotls by vitamin a treatment. the innervation of three replicated proximal muscles was studied by using retrograde transport of horseradish peroxidase. these were the forelimb muscles biceps (seven cases) and anconeus (five cases) and the hindlimb muscle puboischiotibialis (five cases). in two cases (both of anconeus) innervation was from a correct motorneuron pool. in the other 15 cases the innervation was from ... | 1985 | 2410931 |
| a horseradish peroxidase study of motorneuron pools of the forelimb and hindlimb musculature of the axolotl. | motorneuron pools innervating axolotl limb muscles have been investigated by using the retrograde neuronal tracer horseradish peroxidase. four muscles in the forelimb (biceps, anconeus, flexor digitorum and extensor digitorum) and four functionally equivalent muscles in the hindlimb (puboischiotibialis, iliotibialis, flexor digitorum and extensor digitorum) were studied. motorneuron pools were characterized by using four criteria: position in the rostrocaudal axis; position of the median in the ... | 1985 | 2410930 |
| 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 |
| the effect of retinoic acid on positional memory in the dorsoventral axis of regenerating axolotl limbs. | we investigated the effect of retinoic acid (ra) on pattern regulation in the dorsoventral (dv) axis of regenerating axolotl limbs. half and double half dorsal and ventral zeugopodia (lower arms or legs) were amputated through their distal ends, and 4 days later the animals were injected intraperitoneally with 50 (large animals) or 100 (small animals) micrograms ra/g body wt. half and double half dorsal and ventral zeugopodia of uninjected axolotls, and sham-operated zeugopodia of untreated and ... | 1990 | 2358123 |