Publications

lactate dehydrogenase isoenzyme pattern as a marker of lymphocyte populations in the axolotl (ambystoma mexicanum).		1981	6976277
[histochemical study of the cholinesterases of various formations of the vertebrate endbrain].	histochemical studies have been made on true (ache) and false (bche) cholinesterases in different parts of the telencephalon of amphibians, reptiles and mammals. the data obtained indicate that the enzymic localization depends on both the level of the development of the brain and phylogenetic age of its individual formations. in the telencephalon of ambystoma mexicanum, high concentration of ache was found in vascular-capillary network, in other investigated amphibians (triturus vulgaris, rana t ...	1981	6976662
immunofluorescence studies for myosin, alpha-actinin and tropomyosin in developing hearts of normal and cardiac lethal mutant mexican axolotls, ambystoma mexicanum.	recessive mutant gene c in axolotl embryos results in an absence of normal heart function. immunofluorescence studies were done to determine the distributions of myosin, tropomyosin and alpha-actinin in the hearts of normal and mutant siblings. anti-myosin specifically stains the a bands of myofibrils in normal hearts and reveals a progressive increase in myofibril organization with development. mutant hearts display less staining for myosin than normal and localization is mainly in amorphous co ...	1980	6989943
intercalary regeneration of symmetrical thighs in the axolotl, ambystoma mexicanum.		1980	7000578
morphogenetic properties of the skin in axolotl limb regeneration.	a study has been made of the morphogenetic properties of anterior and posterior skin from the lower forelimb of the axolotl. the basic experiment consisted of a graft of a half cuff of skin from a donor to a host limb followed by a 2-week healing period, amputation through the graft, and a study of the resulting regenerate. limbs with double posterior skin formed double posterior regenerates and, in contrast, limbs with double anterior skin formed normal or slightly hypomorphic regenerates. post ...	1980	7003051
comparative immunocytochemical localization of prolactin and somatotropin in the pituitaries of lepidosiren paradoxa, rana temporaria and ambystoma mexicanum.	the cellular binding sites of anti-oprl igg and anti-bsth igg were demonstrated in the pituitary glands of lepidosiren paradoxa, rana temporaria and ambystoma mexicanum by means of the unlabeled antibody enzyme method by light and electron microscopy (the latter only in lepidosiren). with the light microscope prl or prl-like substances and sth or sth-like substances were revealed in two different cell types in the distal lobe corresponding to the acidophils. however, as a result of the insuffici ...	1981	7018691
regulation of antibody synthesis in the x-irradiated mexican axolotl.	the effects of x-irradiation were studied on the mexican axolotl antibody synthesis. to reduce the anti-horse red blood cell (hrbc) antibody titers, 150 rd and smaller doses are ineffective, 200-450 rd are increasingly effective, and 700 rd are maximally effective (and lethal). a significant enhancement of the anti-hrbc titers was observed in low doses (50-150 rd x-irradiated animals). this enhancement was also observed when a low x-ray dose was applied only on the thymic areas. in whole body, b ...	1981	7028489
the ability of localized implants of whole or minced dermis to disrupt pattern formation in the regenerating forelimb of the axolotl.	the ability of localized grafts of dermis to alter pattern formation in the regenerating limb of the axolotl was studied. longitudinal pieces of skin (1/4 of circumference of the limb) were removed from either the anterior or the posterior surface of the upper forelimb. epidermis was removed by immersion in versene followed by mechanical stripping. the resulting dermis was cross transplanted directly beneath the skin on the opposite side of the limb from which it originated. after 5 days of heal ...	1981	7034520
the regeneration of axolotl limbs covered by frog skin.		1982	7042417
constant occurrence of an ipsilateral retino-tectal projection in the axolotl (ambystoma mexicanum) revealed by horseradish peroxidase tracing.	cut optic nerves were filled orthogradely with horseradish peroxidase (hrp) to reveal contralateral and ipsilateral retino-tectal projections in the axolotl, by light and electron microscopy. the ipsilateral projection is small but consistently present. it is concentrated in the rostral tectum particularly the dorsomedial and ventrolateral areas. the results are compared with findings in other vertebrates.	1980	7052461
neural crest cell behavior in white and dark embryos of ambystoma mexicanum: epidermal inhibition of pigment cell migration in the white axolotl.		1982	7054006
prospective forebrain-midbrain from axolotl neurulae can be reprogrammed to differentiate as mauthner cell-containing medulla.	in premetamorphic amphibians, the mauthner cells (m-cells), a single pair of large neurons, are present in the medulla at ear level. m-cells are easily identified morphologically. lability of the major axes of the cns in the axolotl (ambystoma mexicanum) through midneural plate stages suggests that regionalization of the cns does not occur prior to that time. thus, prospective forebrain-midbrain from early midneurulae was unilaterally substituted for prospective hindbrain in hosts of the same st ...	1982	7055713
evidence for low-molecular weight antibodies in the serum of a urodele amphibian, ambystoma mexicanum.	adult axolotls (a. mexicanum) were hyperimmunized with the haptenic determinant, azobenzene-arsonate (ars). specific antibodies were isolated from their serum by immune-affinity chromatography on immobilized ars columns. analysis of the specific ars-binding molecules by sodium dodecyl sulfate polyacrylamide gel electrophoresis (sds-page) indicated that these animals were capable of producing both high molecular-weight (presumably igm) and low molecular-weight antibodies to the ars hapten. the lo ...	1982	7061117
synaptogenesis and its relation to growth of the postsynaptic cell: a quantitative study of the developing mauthner neuron of the axolotl.	we describe the relation between growth and branching of an identified dendrite and the formation of synapses on its surface during a 3 1/2-day period early in development. we studied the lateral dendrite and the adjacent lateral perikaryon of the mauthner cell (m-cell) during embryonic stages 39-43 in the axolotl ambystoma mexicanum. reconstructions from light micrographs of serial sections through the cell revealed that during this interval the dendrite elongates rapidly, and large numbers of ...	1982	7061738
the transplantation of eyes to genetically eyeless salamanders: visual projections and somatosensory interactions.	eyes were transplanted from normal axolotls to eyeless mutants, and several anatomical and physiological observations were made on the central visual centers in these animals. some central projections were bilateral to the optic centers of the thalamus and midbrain, some traveled ipsilaterally to the same centers, and the rest grew down the spinal cord. this is similar to what has been found in eyes transplanted to normal hosts. the type of projection made in eyeless hosts correlated with the si ...	1982	7062113
electrophysiological evidence of electroreception in the axolotl siredon mexicanum.		1982	7063140
corticosteroid action on lymphocyte subpopulations and humoral immune response of axolotl (urodele amphibian).	the effect of in vivo hydrocortisone (hc) treatment on thymocytes, splenic and blood lymphocytes and on allogeneic and humoral immune responses were investigated in the axolotl (urodele amphibian). hc induces a profound lymphocytopenia in the thymus (83% hc sensitive) and the spleen (50% hc sensitive) but not in the blood. the density gradient analysis of hc-treated axolotls showed that thymic cell populations of light density were more sensitive than populations of high density. the timing of h ...	1982	7076277
evidence that patterning mechanisms in developing and regenerating limbs are the same.	some amphibians have the ability to form new limbs throughout their lives. the essential similarity between limb regeneration and the original development of the limb is that both involve the elaboration of new patterns of structures. while some investigators believe that the two developing systems use similar mechanisms to generate the limb pattern, others have stressed the basic differences in developing the regenerating limbs, and have concluded that different mechanisms exist. both developin ...	1982	7088182
quantification of tropomyosin by radioimmunoassay in developing hearts of cardiac mutant axolotls, ambystoma mexicanum.	recessive mutant gene c in axolotls results in a failure of embryonic heart function. earlier morphological studies showed that the mutant myocardial cells lack organized sarcomeric myofibrils. electrophoresis and immunofluorescent studies suggested that the mutant heart cells contain substantial amounts of actin, myosin and alpha-actinin; however, tropomyosin appeared deficient. in the present study, we employed a newly developed extremely sensitive solid-phase radioimmunoassay method to quanti ...	1982	7107867
the growth of segmental nerves from the spinal cord to the hind limb-bud in the axolotl.	it has been concluded from previous experiments involving the growth of segmental nerves from the amphibian spinal cord to the limb-bud that axons are attracted to the limb-bud region by their target tissue (hamburger, 1929; hughes and tschumi, 1958). in the present study this hypothesis has been tested by obstructing the pathways over which the nerves normally grow. it was found that for those nerves which marginally obstructed far fewer axons were able to reach their target. the spinal ganglia ...	1982	7115218
partial denervation effects on limb cartilage regeneration.	partially innervated axolotl arms gave regenerates of reduced size with deficient skeletal element replacement. this deficiency was most pronounced when nerve 4 (the largest of the brachial nerves) estimated to make up 50-60% of forelimb axons was removed by repeated resection. nerve 3 or 5 removal gave less pronounced reduction deformities in the newly formed regenerate. the dependency of skeletal element formation upon nerves is emphasized but does not follow a strict segmental subtraction in ...	1982	7125236
pattern regulation during regeneration of embryonically produced symmetrical forelimbs in the axolotl, ambystoma mexicanum.	embryonic axolotls (stages 32-34) underwent surgery during which a graft of flank tissue was transferred from a donor animal to the anterior margin of the forelimb field in a host animal. double-posterior forelimbs containing from one to eight digits developed. these limbs were amputated at a level proximal to the elbow to assess their regenerative ability. the majority (62%) of these limbs failed to regenerate externally visible structures. symmetrical limbs bearing five digits or more than fiv ...	1982	7130935
protein synthesis during limb regeneration in the axolotl.	a study has been made of limb regeneration in the axolotl using two-dimensional gel electrophoresis of proteins labelled with [35s] methionine. in the early stages of regeneration seven proteins are identified which are specific to the mesenchyme and thirteen which are specific to the epidermis. these is very little change in the gel pattern until the onset of overt cytodifferentiation upon which the muscle and cartilage become substantially different both from each other and from the blastemal ...	1982	7142900
retinofugal pathways from albino eyes embryonically transplanted to normal and albino axolotls.	albino axolotl eyes were transplanted embryonically to normal and albino axolotl hosts. the animals were allowed to mature for several months and then their transplanted eyes were injected with tritiated proline. the projections from these albino eyes were compared with those obtained from similar transplants of normally pigmented eyes. special attention was paid to the crossed and uncrossed components of the projections. no differences were found between normal and albino transplants. these res ...	1982	7150982
peaks of neuronal membrane antigen and thyroxine in larval development of the mexican axolotl.		1982	7160616
a variant cardiac tropomyosin in the salamander, ambystoma mexicanum.		1982	7182078
identification and morphometric evaluation of the synapses of optic nerve afferents in the optic tectum of the axolotl (ambystoma mexicanum).	ther terminals of retinal afferents in the tectum of the axolotl have been identified ultrastructurally using techniques of horseradish peroxidase-filling and degeneration. the mitochondria in filled structures show a characteristic electron-lucent matrix. after both eyes have been removed, terminals with light mitochondria disappear from the area known to receive an optic input. in this area the presence of light mitochondria is almost always diagnostic of the retinal origin of a bouton. the sy ...	1981	7214469
vitellogenin synthesis and characterisation of the liver estrogen receptor in the neotenous salamander ambystoma mexicanum.		1981	7227646
antigen trapping in ambystoma mexicanum. role of secondary lymphoid organs.		1981	7238968
[effects of concanavalin a on neural induction in the young gastrula of the axolotl (ambystoma mexicanum shaw. ) and pleurodele (pleurodeles waltlii michah.)].	presumptive ectoderm from young gastrulae of the pleurodele and the axolotl was treated with concanavalin a(5-25 micrograms/ml). then, it was combined, in a sandwich, with the dorsal lip of the blastopore and cultured in vitro for 5-7 days. the results of the experiments show that the treated ectoderm becomes more fragile than untreated control ectoderm. nevertheless, the neural induction and the histological differentiation of the neural tissue appeared in a rather normal fashion.	1981	7257883
behavioral and electrophysiological study of cutaneous trigeminal nerves in axolotls. i. normal innervation and reinnervation following nerve section.	behavioral responses to light tactile stimulation of the skin of the head of axolotls were variable in occurrence but were of a constant pattern. retraction of the eyes and gills followed stimulation of dorsal but not ventral skin. ventral skin yielded lowering of the head. touching near the lips caused turning of the head and a snap towards the stimulator. following section and regeneration of divisions of the trigeminal vth nerve, normal behavioral responses returned in 7-17 weeks. afferent ac ...	1981	7272780
behavioral and electrophysiological study of cutaneous trigeminal nerves in axolotls. ii. the effects of cross-anastomosis of nerves.		1981	7272781
regeneration of subnormally innervated axolotl arms.	forearms of juvenile axolotls contain about 5000 axons, of which only 25% are myelinated and visible by light microscopy. virtually all the axons degenerate after transection of the brachial plexus, but repeated operations fail to keep the arm completely denervated. regrown nerve fibres were detected by electron microscopy after 6 weeks of attempted denervation and related to the quantity usually considered necessary for limb regeneration. such arms regenerated quite normally, provided their inn ...	1981	7276803
enzyme involved in dna replication in the axolotl. i. analysis of the forms and activities of dna polymerase and dna ligase during development.		1981	7286413
enzymes involved in dna replication in the axolotl. ii. control of dna ligase activity during very early development.		1981	7286414
the movement of the prospective eye vesicles from the neural plate into the neural fold in ambystoma mexicanum and xenopus laevis.		1981	7286445
evidence that the premature death mutation (p) in the mexican axolotl (ambystoma mexicanum) is not an autonomous cell lethal.	cell-lethal developmental mutations, which are presumed to affect the viability of all cells in a mutant embryo, have been distinguished from other development lethals on the basis of the results of parabiosis and transplant experiments. premature death (p), previously classified as a cell lethal, does not survive parabiosis. however, transplants involving mutant eye, flank epidermis and primordial limb tissue all survived on a normal recipient. the mutant, therefore, cannot be considered a true ...	1980	7310271
pattern regulation and the origin of extra parts following axial misalignments in the urodele limb bud.	pattern regulation following axial misalignments in the stage-38+to stage-40 urodele limb bud was studied on one newt and two salamander species. grafts of the distal tip of the limb bud were made to the stump of a host limb bud from which a similar piece had been removed. the grafts were positioned with either their anteroposterior, dorsoventral, or both of these axes reversed with respect to the host axes. mirror-imaged duplications, positioned posteriorly or both anteriorly and posteriorly, o ...	1980	7310274
amphibian pronephric duct morphogenesis: segregation, cell rearrangement and directed migration of the ambystoma duct rudiment.	the axolotl pronephric duct rudiment is readily accessible to both sem observation and surgical manipulation. the rudiment segregates from the dorsal part of the lateral mesoderm and then extends caudally along the ventrolateral border of the segmenting comites, eventually contacting the cloacal wall. the marked thinning of the rudiment which accompanies this migration is paralleled by a corresponding reduction in cell number across the duct's diameter and by caudad translocation and elongation ...	1981	7310283
[model studies of the effect of structural changes in cleaving embryo on electrical parameters of cellular interactions].	two models of the embryo developing from one initial cell by cleavage division are considered. equivalent electrical schemes were constructed, changes in electrical coupling coefficient (kec) and input resistance (ri) of the embryos during cleavage were estimated. considerable influence of cleavage-related changes of membrane parameters on kec and ri appears at the first five--ten cleavages and essentially depends on the ratio of contact and incontact membrane resistances. a comparison of the es ...	2007	7317491
mitochondrial morphology in the spermatozoa of the mexican axolotl, ambystoma mexicanum.	thin-section and freeze-fracture electron microscopy of immature and mature spermatozoa of the mexican axolotl, ambystoma mexicanum, revealed numerous small spherical mitochondria with diameters ranging from 0.15 to 0.22 micrometers. both the spherical form and the small size of these mitochondria were confirmed by serial thin-section studies. in mature spermatozoa, the mitochondria are located in the midpiece region, in tight contact with each other, exhibiting an almost crystalline arrangement ...	1981	7320076
probability aspects of supernumerary production in the regenerating limbs of the axolotl, ambystoma mexicanum.	the applicability of deterministic models, and in particular the polar co-ordinate model of french, bryant & bryant (1976), to the regenerative process has been investigated by performing ipsilateral blastemal rotations of varying angle on the fore and hind limbs of the axolotl. the results show that the frequency of supernumerary production rises with increasing angle to reach a peak at 180 degree and then falls off more rapidly, giving rise to an asymmetric distribution curve. the position of ...	1981	7334295
[autoradiographic investigations on postnatal proliferative activity of the telencephalic and diencephalic matrix-zones in the axolotl (ambystoma mexicanum), with special references to the olfactory organ (author's transl)].	the localization and proliferative activity of the matrix-zones has been investigated in the telencephalon and in the diencephalon of 21 axolotls (ambystoma mexicanum) by means of autoradiographs, after injection of tritiated thymidine at different stages of the postnatal life. there are no previous detailed autoradiographical reports on postnatal brain development in the axolotl. matrix-zones (i.e. ventricular and subventricular zone) exist in the dorsal part and in the ventral part of the tele ...	1981	7336815
comparative analysis of amphibian somite morphogenesis: cell rearrangement patterns during rosette formation and myoblast fusion.	detailed sem observations of the changes in cellular morphology, arrangements, and contacts that occur during the process of somite formation were made in two species of urodele amphibians, ambystoma mexicanum and pleurodeles waltlii, and one species of anuran amphibian, rana sphenocephala. after fixation, embryos were fractured transversely, horizontally, and parasagittally, and the intrasomitic cellular arrangement pattern was examined with the sem. it was found that ambystoma and pleurodeles ...	1981	7338706
cellular contacts between hindbrain and prospective ear during inductive interaction in the axolotl embryo.	in the amphibian embryo, beginning in the late neurula and continuing through midtailbud stages, the developing medulla exerts an inductive influence on the prospective ear, effecting its determination. fine structural analysis of the region of closest apposition between the two tissues in the axolotl (ambystoma mexicanum) revealed that during this period, there is a significant increase in the surface area of the apposed cells through the projection of long finger-like processes that traverse t ...	1981	7338713
suppression of first cleavage in the mexican axolotl (ambystoma mexicanum) by heat shock or hydrostatic pressure.	androgenetic diploid axolotls were produced by ultraviolet inactivation of the egg pronucleus shortly after fertilization, followed by suppression of the first cleavage division by hydrostatic pressure or heat shock. after treatment at 14,000 psi for 8 minutes, diploidy was restored in 74% of the embryos, but only 0.8% survived to hatching. a 36-37 degrees c heat shock of 10-minutes duration, applied 5.5 hours after the eggs were collected, yielded a slightly lower percentage of diploids. howeve ...	1981	7338728
hemoglobins of an amphibia, the neotenous ambystoma mexicanum. complete amino-acid sequence of the alpha chain of the major component using automatic solid-phase edman degradation.	the primary structure of axolotl (neotenous ambystoma mexicanum) alpha chain has been determined. nh2-terminal sequence data were performed using the solid-phase method. complete amino acid assignments were deduced from the sequences of peptides obtained after cleavage with cyanogen bromide; the methionine-containing peptides, isolated from alpha chain tryptic digest, allowing the alignment of these fragments. all overlaps have been clearly established. axolotl alpha chain contains 142 residues, ...	1980	7358052
melanogenesis in oocytes of wild-type and mutant albino axolotls.		1980	7371975
regeneration of symmetrical forelimbs in the axolotl, ambystoma mexicanum.		1980	7371977
distal transformation from double-half forearms in the axolotl, ambystoma mexicanum.		1980	7371978
neural crest cell migration in relation to extracellular matrix organization in the embryonic axolotl trunk.		1980	7371990
spatial distribution of abundant proteins in oocytes and fertilized eggs of the mexican axolotl (ambystoma mexicanum).		1980	7372013
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
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
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
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
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
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
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
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
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
evidence of the first genetic activity required in axolotl development.		1980	7444204
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
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
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
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
characterization of immunoglobulin heavy chain variable regions in the mexican axolotl.		1994	7506234
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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