Publications

evidence of the first genetic activity required in axolotl development.		1980	7444204
on spontaneous skin tumours in amphibia.	in 7 from 320 rana temporaria grass frogs and 16 from 978 rana ridibunda pond frogs, the 31 and 47 spontaneous skin tumors respectively, were observed. the tumors were represented by cystadenopapillomas and adenocarcinomas, and developed from epithelium of skin mucous glands. the spontaneous pigment tumors (melanophoromas) were found in 2 axolotls ambistoma mexicanum. these tumors developed from hyperplastic melanophores in pigment spots and focal proliferations of melanophores located deeply in ...	1980	6969862
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
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
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
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
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
has prolactin an intermedin-like activity on the integument of the axolotl?	skin explants of the neotenic form of ambystoma tigrinum (axolotl) have been kept in culture during several days. when alpha-msh or prolactin are added to the medium, a dispersion of melanin in melanosomes is observed. the reaction is reversible in the case of prolactin when the explants are transferred in the medium without hormones. furthermore with prolactin, expansion of melanin in dermal melanophores is a more permanent and highly reproducible phenomenon, compared with the action of alpha-m ...	1981	6176199
[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
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
thymus dependency in anti-trinitrophenyl (tnp) binding responses in the spleen of ambystoma mexicanum. effects of thymectomy and anti-thymocyte serum treatments.		1981	6970685
equilibrium properties of a voltage-dependent junctional conductance.	the conductance of junctions between amphibian blastomeres is strongly voltage dependent. isolated pairs of blastomeres from embryos of ambystoma mexicanum, xenopus laevis, and rana pipiens were voltage clamped, and junctional current was measured during transjunctional voltage steps. the steady-state junctional conductance decreases as a steep function of transjunctional voltage of either polarity. a voltage-insensitive conductance less than 5% of the maximum remains at large transjunctional vo ...	1981	6259274
the movement of the prospective eye vesicles from the neural plate into the neural fold in ambystoma mexicanum and xenopus laevis.		1981	7286445
enzymes involved in dna replication in the axolotl. ii. control of dna ligase activity during very early development.		1981	7286414
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
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
behavioral and electrophysiological study of cutaneous trigeminal nerves in axolotls. ii. the effects of cross-anastomosis of nerves.		1981	7272781
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
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
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
[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
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
vitellogenin synthesis and characterisation of the liver estrogen receptor in the neotenous salamander ambystoma mexicanum.		1981	7227646
two actin variants in developing axolotl heart.		1981	6894432
[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
antigen trapping in ambystoma mexicanum. role of secondary lymphoid organs.		1981	7238968
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
lactate dehydrogenase isoenzyme pattern as a marker of lymphocyte populations in the axolotl (ambystoma mexicanum).		1981	6976277
the serotonergic somatosensory projection to the tectum of normal and eyeless salamanders.	the spinotectal somatosensory projection was compared in normal, genetically eyeless, and embryonically manipulated salamanders. in normal animals, serotonin fluorescence was restricted to the intermediate tectalneuropil. this same region showed both high levels of serotonin uptake and somatosensory single unit electrical activity. in mutant eyeless salamanders and in normal animals enucleated early in development, serotonin fluorescence, serotonin uptake, and somatosensory activity were present ...	1981	30153710
[effects of exogenous tsh on the thyroid activity of adult or neotenic amphibians].	in adult anuran and neotenic urodela, bred in laboratory conditions, the levels of plasma thyroid hormones are undetectable (t3 less than 50 ng/100 ml, t4 less than 5 ng/100 ml). thyroid function can be reactivated after ovine tsh treatment. under those conditions, metamorphosis is induced in the axolotl and t4 plasmatic levels reaches 0,53 +/- 0,13 micrograms/100 ml and those of t3 9 +/- 2,64 ng/100 ml. in adult anuran, thyroid reactivation under thyrotropic treatment determines an increased se ...	1982	6220788
carbamoyl-phosphate synthase (ammonia) of rat and axolotl liver: determination of immunological cross-reactivity without purification of the axolotl enzyme.	a method has been developed to establish the degree of cross-reactivity of an antiserum raised against purified carbamoyl-phosphate synthase (ammonia) from adult rat liver, toward a homologous enzyme from another species without purification of the latter enzyme. for that purpose the ratio between enzyme activity and enzyme protein, i.e., the molecular specific activity in crude liver extracts, was determined by two independent methods. when the molecular specific activity was determined by mean ...	1982	6754856
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
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
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
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
expansion of the visual projection to the tectum of axolotls during metamorphosis.	during artificially induced metamorphosis in axolotls, the indirect visual projection from the ipsilateral eye develops followed by the expansion of the contralateral direct projection to occupy most of the tectal surface. during expansion the ipsilateral input is temporarily lost indicating the functional interdependence of the two projections. final stabilization of the projections and congruence of the ipsilateral and contralateral inputs is achieved a month after arrival on land.	1982	6185185
enzyme clusters during the metamorphic period of ambystoma mexicanum: role of thyroid hormone.	enzyme activities and dna content have been measure in axolotl liver during the metamorphic period (4-8 months after spawning). three different types of enzyme activity profiles were observed. in the type i profile (carbamoyl-phosphate synthase, arginase, ornithine transcarbamoylase, and glutamate dehydrogenase) enzyme activity is high in the youngest animals studied, and shows a minimum at 5 months followed by a maximum at 8 months of age. thereafter activities do not change or slightly decreas ...	1982	6128371
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
axial organization of the regenerating limb: asymmetrical behaviour following skin transplantation.	an extensive series of skin grafting operations has been performed to investigate axial organization in the regenerating axolotl limb. semicircular cuffs of skin from either anterior, posterior, dorsal or ventral surfaces were exchanged between right and left limbs thereby creating limbs with double anterior, double posterior, double dorsal or double ventral skin, all with normal internal tissues. both fore and hindlimbs were used at both upper and lower limb levels. following amputation through ...	1982	6754846
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
early grey crescent formation experimentally induced by cycloheximide in the axolotl oocyte.	the effects of cycloheximide (ch) on grey crescent formation in artificially maturedambystoma mexicanum oocytes were determined. ch induced grey crescent formation after a few hours, especially after a 45° to 90° rotation from the vertical animal-vegetal axis. with low concentrations of ch (about 0.5 ng/oocyte), meiosis was still able to proceed normally to the stable second metaphase stage, but higher concentrations blocked it after 1st polar body extrusion and an interphasic nucleus appeared. ...	1982	28305050
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
the regeneration of axolotl limbs covered by frog skin.		1982	7042417
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
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
electrophysiological evidence of electroreception in the axolotl siredon mexicanum.		1982	7063140
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
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
neural crest cell behavior in white and dark embryos of ambystoma mexicanum: epidermal inhibition of pigment cell migration in the white axolotl.		1982	7054006
the alveolar-lining layer in the lung of the axolotl, ambystoma mexicanum. an electron-microscopic study using heavy metal complexes.	lungs of neotenic larvae of ambystoma mexicanum were prepared for maintaining the air-tissue boundary during aldehyde fixation. four methods of postfixation were applied: 1) osmium tetroxide followed by en-bloc staining with uranyl acetate and phosphotungstic acid, 2) ruthenium redosmium tetroxide, 3) osmium tetroxide-ferrocyanide, and 4) tannic acid-osmium tetroxide. three types of cells line the inner surface of the axolotl lung: 1) pneumocytes, covering the capillaries with flat cellular exte ...	1982	6174238
spastic mutant axolotl: identification of a phenocopy pathway with implications for the control of axolotl swimming by the vestibulocerebellum.	the spastic mutant axolotl shows abnormal swimming behavior, which includes a preponderance of "embryonic" swimming elements (coils) versus mature swimming elements (sinusoids) and a failure to entrain sinusoids into a prolonged swimming sequence. the mutant also shows anatomical disorganization in the area acousticolateralis and cerebellar auricle, but it is unclear (1) to what extent the behavioral abnormalities are traceable to the vestibulocerebellar defect or (2) how the vestibulocerebellar ...	1983	6643720
the effect of vitamin a on the regenerating axolotl limb.	these experiments describe further investigations into the effects of vitamin a on regenerating limbs. the effects of different retinoids, the time of administration, concentration of vitamin a and histological, autoradiographic and histochemical studies are reported. the most obvious result of vitamin a treatment is to cause proximal elements to regenerate from distal amputation levels, that is to cause serial reduplication of pattern in the proximodistal axis. retinoic acid was the most potent ...	1983	6655434
the effect of vitamin a on limb regeneration in rana temporaria.	previous experiments in which vitamin a has been administered to developing or regenerating limbs have shown that different limb axes are affected. in regenerating axolotl limbs, serial reduplications in the proximodistal axis are produced. in the developing chick limb bud, mirror-imaged reduplications in the anteroposterior axis are produced. results reported here on rana temporaria limb buds reveal that vitamin a causes both effects to occur. that is, limbs are both serially reduplicated in th ...	1983	6603380
fertilization of amphibian eggs: a comparison of electrical responses between anurans and urodeles.	in pleurodeles waltl and ambystoma mexicanum, which exhibit physiological polyspermy, the membrane potential in most eggs did not change in any consistent pattern during 45 min after fertilization; in some cases, a slow hyperpolarization began 5 to 15 min after insemination and continued for 10-15 min. these eggs then slowly depolarized, reaching a stable value of -10 to +10 mv, about 45 min after fertilization. membranes of eggs activated by a23187 or by electrical stimulus showed a similar beh ...	1983	6603379
gross morphological analysis of limb regeneration in postmetamorphic adult ambystoma.	due to the great disparity between regeneration times for the larval salamander (40 days), axolotl (30+ days), newt (44 days), and adult salamander (155 to 370 days), a staging system was devised so correlative comparisons could be made between regenerative model systems. the sequence was based on two criteria: 1) the stages should be similar to previously reported sequences for the newt, axolotl, and larval salamander, and 2) the stages must be readily recognizable by examination of the externa ...	1983	6614512
experimental studies on a lethal gene (t) in the mexican axolotl, ambystoma mexicanum.	in the mexican axolotl, ambystoma mexicanum, the developmental mutation lethal t is inherited as a simple mendelian recessive. mutant larvae failed to feed and died, on the average, 17 days after hatching. unfed wild-type larvae died an average of 23 days after hatching. by 15 days, forelimb development had progressed further in the wild type; a cartilaginous scapula and humerus were present, but no cartilage was seen in the mutant limb. histological examination indicated that the visceral carti ...	1983	6886665
muscle and cartilage differentiation in axolotl limb regeneration blastema cultures.	a tissue culture system is described for explants of mesenchyme from ambystoma mexicanum limb regeneration blastemas. explants were cultured on collagen substrate for 3 weeks in minimal essential medium supplemented with the hormones insulin, thyroxine, somatotropin, and hydrocortisone, plus beef embryo extract (ee), 2%. this medium supported extensive cell migration onto the substrate followed by cell proliferation and differentiation of both cartilage matrix and myotubes. cultures on plastic s ...	1983	6886662
assessment of mutagenic damage following ethyl methanesulfonate mutagenesis in the axolotl (ambystoma mexicanum).	when male axolots (ambystoma mexicanus) were treated with 100 mg/liter of ethyl methanesulfonate (ems), a dominant lethal effect was obtained. embryonic survival of f1 progeny was most severely reduced between about 50 and 150 days after treatment. dominant lethal lesions probably consist of chromosome breaks that lead to loss of parts of chromosomes or entire chromosomes. the appearance of embryos with a single nucleolus was used to assess this type of damage. the peak incidence of such embryos ...	1983	6886657
pattern regulation in the anterior half of the embryonically produced symmetrical forelimb of the axolotl, ambystoma mexicanum.	symmetrical forelimbs were created in the axoltl by performing surgery on embryos at stages 32-34. the technique of j.m.w. slack (j. embryol. exp. morphol., 39:151-168, 1977) was utilized. several experiments were then performed to test the ability of these symmetrical forelimbs to participate in pattern formation. when symmetrical limbs were amputated without previous surgery, 58% failed to regenerate. when symmetrical limbs were wounded in the plane of symmetry and permitted to heal for 30 day ...	1983	6613906
[an anatomical study of teeth in the axolotl (siredon mexicanum)].		1983	6585764
control of dna ligase molecular forms in nucleocytoplasmic combinations of axolotl and pleurodeles.	a light form of dna ligase (ec 6.5.1.2), the only form present in oocytes of the axolotl (ambystoma mexicanum), has been shown to be replaced by a heavy form of the enzyme when the egg enters cleavage. this early biochemical event has been assumed to rely on direct nuclear input. sucrose gradient analysis permits discrimination between enzymes from axolotl and the sharp-ribbed salamander (pleurodeles waltlii) for both heavy and light enzymatic forms of dna ligase. genetic activity of blastula nu ...	1983	6574490
inhibition of protein synthesis elicits early grey crescent formation in the axolotl oocyte.	in the axolotl (ambystoma mexicanum shaw), it was recently shown that cycloheximide (ch) could induce early grey crescent formation (egc) in non-activated oocytes, maturing in vitro (grinfeld and beetschen 1982). since it was not proved that egc was a consequence of protein synthesis inhibition rather than a side-effect of the drug, experiments were performed using microinjections of a quite different inhibitor, diphtheria toxin (dt). this toxin also appeared to elicit egc. incorporation of (3h) ...	1983	28305127
the structure of supernumerary limbs formed after 180 degrees blastemal rotation in the newt triturus cristatus.	the structure of supernumerary limbs formed following 180 degrees ipsilateral blastema rotations in the arm of the newt triturus cristatus is analysed. both the skeletal pattern and the muscle patterns are examined. as is the case after comparable experiments in the axolotl (see, for example, maden & mustafa, 12982) the extra limbs which form show a range of anatomies. limbs symmetrical about the dorsal-ventral and anterior-posterior axis are reported as well as some limbs which were part symmet ...	1983	6886592
differences between embryos and adults in the plasticity of somatosensory afferents to the axolotl tectum.	the plasticity of somatosensory afferents in the adult axolotl tectum was studied in two ways. first, normal adult axolotls were monocularly enucleated, and second, adult animals which had been monocular since embryogenesis had the tectum contralateral to the remaining eye excised. after a survival time of about one year the brains of these animals were studied electrophysiologically and histochemically. in the enucleated adults, the deprived tectum lacked visual activity, and the acetylcholines ...	1983	6850352
dna ligase in axolotl egg: a model for study of gene activity control.	replacement of the light form of dna ligase (6 s) by the heavy form (8 s) in activated egg of axolotl has been studied as a model for change in genetic activity exerted by the female pronucleus. nuclear transplantation shows that a blastula nucleus is able to govern the replacement of the light ligase by the heavy one. the result is not the same if the grafted nucleus is taken from an androgenetic embryo, devoid of the heavy enzyme. therefore the change in the properties of the female pronucleus ...	1983	6832475
neurulation in the mexican salamander (ambystoma mexicanum): a drug study and cell shape analysis of the epidermis and the neural plate.	we analysed the neurulation movements in the mexican salamander ambystoma mexicanum. embryos were exposed to colchicine or nocodazole prior to neural fold formation. exposure to these drugs prevented the anterior neural folds from closing. neurulation however proceeded normally in the posterior regions of the embryo. we were unable to find apically constricted cells in the neural plate of colchicine-blocked neurulae. only rounded-up neural plate cells were present (semithin sections). this situa ...	1983	6684145
hormonal control of glycogenolysis and the mechanism of action of adrenaline in amphibian liver in vitro.	in in vitro cultures of liver from ambystoma mexicanum glycogenolysis was stimulated by adrenaline, glucagon, and vasopressin in a dose-dependent manner. maximum activity was seen at 10(-6) m hormone while 10(-9) m was without effect. dibutyryl cyclic amp (10(-3) m) stimulated glycogenolysis maximally although 10(-5) m had no effect. the glucose release brought about by adrenaline was blocked by the beta-adrenergic antagonist propranolol but not by prazosin or yohimbine which are alpha 1- and al ...	1983	6301936
reversal of developmental competence in inverted amphibian eggs.	inverted amphibian embryos were employed for an analysis of pattern formation in early embryogenesis. axolotl (ambystoma) and xenopus eggs were inverted prior to the first cleavage division and permitted to develop upside down to the early gastrulation stage. in both cases the cleavage patterns of the animal and vegetal hemispheres were reversed. by gastrulation, however, developmental arrest began, and no inverted embryos developed beyond neurulation. the state of competence of the animal and v ...	1983	6683745
positional information in the forelimb of the axolotl: properties of the posterior skin.	two series of experiments were carried out to investigate the properties of the positional information carried by posterior skin of the axolotl forelimb. the skin was assayed by grafting it to the anterior side of a normal limb and then amputating through the graft region. the formation of a double posterior regenerate indicates that the grafted skin carried the posterior coding. in the first series, double posterior limbs were created by grafting posterior half limb rudiments to the flank of ta ...	1983	6348201
effects of immunization, adult thymectomy and irradiation on axolotl spleen lymphocytes: discontinuous ficoll density gradients analysis.		1983	6873432
regional differences of protein synthesis in the limb regeneration blastema of the axolotl.		1983	6828516
morphogenesis of the regenerating limb blastema of the axolotl: shape, autonomy and pattern.		1983	6828512
[cell satellites and postsatellites in the muscle tissue of the adult ambystoma mexicanum].		1983	6662019
fibronectin in early amphibian embryos. migrating mesodermal cells contact fibronectin established prior to gastrulation.	the three-dimensional organisation of fibronectin (fn) in early amphibian embryos (ambystoma mexicanum, pleurodeles waltlii) was studied with the use of antibodies against amphibian-fn. immunofluorescence labelling was performed on whole-mount specimens. it was shown that before gastrulation an extensive extracellular network consisting of anastomosed fn-fibrils underlies the roof of the blastocoel prior to the migration of mesodermal cells. initially, fn-fibrils develop radially on the inner su ...	1983	6640612
[formation of the gray crescent, induced in axolotl oocytes during maturation, depends on factors of nuclear origin].	inhibitors of protein synthesis can elicit the precocious appearance of a grey crescent (gc) in in vitro maturing ambystoma mexicanum oocytes. this treatment however fails to induce gc formation when the oocytes are enucleated before initiation of maturation. the ability to form a gc is reestablished in enucleated oocytes by the injection of nucleoplasm from a normal oocyte, either before or after injection of the inhibitor. in the latter case, the gc appears even though the protein synthesis le ...	1983	6412990
maturation of transplantation antigens in ambystoma mexicanum.	both juvenile (14-16 week) and adult (18 month) ambystoma mexicanum reject skin allografts from adult ambystoma more speedily than they reject such grafts from juvenile axolotls. donor-specific histocompatibility antigen, prepared from splenocytes, is more effective in inhibiting adult host splenocyte migration when the antigen is prepared from spleen cells from adult, rather than from juvenile ambystoma. the thymus is fully developed in juvenile ambystoma, suggesting that the delayed kinetics o ...	1983	6341109
the effects of adenyl compounds on the heart of the axolotl (ambystoma mexicanum).	in the spontaneously beating axolotl atrium, adenosine 5'-triphosphate (atp) produced initial excitation followed by inhibition and then by a secondary excitation. this third phase of the atp response was only seen in electrically driven preparations in the presence of 8-phenyltheophylline (8-pt), an adenosine receptor antagonist. alpha,beta-methylene atp (apcpp), a stable analogue of atp, produced only excitatory effects, while adenosine and beta,gamma-methylene atp (appcp), a slowly degradable ...	1983	6140115
the origin of the mesoderm in an anuran, xenopus laevis, and a urodele, ambystoma mexicanum.	we have investigated whether superficial cells of the blastula contribute to mesodermal structures in the anuran xenopus laevis and the urodele ambystoma mexicanum. the superficial cells alone of late blastulae of both embryos were labelled with bolton-hunter reagent and the embryos were allowed to develop. the progeny of the labelled cells were identified at later stages and the results demonstrate that superficial cells of xenopus blastulae make no significant contribution to the mesoderm, whe ...	1983	6862108
effects of trh, bovine tsh, and pituitary extracts on thyroidal t4 release in ambystoma mexicanum.	circulating levels of t4 are measured by radioimmunoassay after intravenous injection of trh, bovine (b) tsh, and pituitary extracts in the mexican axolotl (ambystoma mexicanum). very low control levels of t4 are found (53 +/- 3 pg/ml (n = 27), but they are increased sevenfold following injection of 1/2 pars distalis extract or 1/2-1/10 iu b-tsh. increased levels following these injections are found in plasma up to 48 hr after the injection. an in vitro assay also indicates that a 1/2 pars dista ...	1983	6413295
size dependence during the development of the amphibian foot. colchicine-induced digital loss and reduction.	localized treatment of the limb buds of the frog, xenopus laevis, and the salamander, ambystoma mexicanum, with the mitotic inhibitor colchicine results in limbs that, when compared with the contralateral control, are smaller in size and have lost skeletal elements. there is a very well defined pattern in terms of what elements are most likely to be lost. for example, frogs that have lost a toe always lose the first toe, while salamanders always lose the fifth. these differences correspond to qu ...	1983	6631320
[nuclear behavior of the growing oocytes of the clawed frog in the cytoplasm of the maturing oocytes of the axolotl].		1983	6641489
the distribution of small ions during the early development of xenopus laevis and ambystoma mexicanum embryos.	the free ion concentrations of na+, k+ and cl- have been measured in the cells and intercellular spaces of developing amphibian embryos using ion-sensitive microelectrodes. ca2+, h+ and buffering capacity have also been measured in the intercellular spaces. the free intracellular na+ and k+ concentrations in the early cleavage stages remain approximately constant at 21 mm and 90 mm respectively. the free intracellular cl- concentration, approximately 60 mm during the egg to 4-cell stage, falls d ...	1983	6655587
isolation of the messenger rna for 8s dna ligase in early developing axolotl egg and its cell free translation.	a new dna ligase activity is expressed when the axolotl eggs enter cleavage. the messenger rna can be labelled by [3h] uridine thereby indicating its de novo synthesis. this new genetic expression is occurring just before cleavage and is the earliest found during amphibian development. the newly synthesized [3h] mrna can be translated in vitro in the rabbit reticulocyte lysate system. the resulting product is a 160 k protein specifically immunoprecipitated with the antiserum directed against 8s ...	1983	6682971
ribosomal 5s genes in relation to c-value in amphibians.	we have measured the amount of 5s-ribosomal dna in the genomes of xenopus laevis, triturus cristatus carnifex and ambystoma mexicanum, three species of amphibians which have widely different c-values. our best estimate is that these organisms have about 24,000, 32,000 and 61,000 5s-genes per haploid genome respectively. a trend to increasing 5s gene copynumber with increasing c-values in amphibians is apparent, probably linked to the need to supply more ribosomes to the larger cells which are as ...	1983	6304650
the genes coding for 4 snrnas of drosophila melanogaster: localization and determination of gene numbers.	four small nuclear rnas (snrnas) have been isolated from drosophila melanogaster flies. they have been characterized by base analysis, fingerprinting, and injection into axolotl oocytes. the size of the molecules and the modified base composition suggest that the following correlations can be made: snrna1 approximately u2-snrna; snrna2 approximately u3-snrna; snrna3 approximately u4-snrna; snrna4 approximately u6-snrna. the snrnas injected into axolotl oocytes move into the nuclei, where they ar ...	1983	6191277
a steady efflux of ionic current predicts hind limb development in the axolotl.	for more than a week prior to the emergence of a hind limb, a steady electric current is driven out of the ventrolateral flank in the immature axolotl, returning through the integument in adjacent regions of the body. a marked peak in the density of this outcurrent could be observed over the exact area of hind limb formation 4 to 6 days prior to its appearance. after a bud projected from the flank, current densities were observed to decrease in magnitude yet localize about the early limb. in abo ...	1983	6663262
axonal pathfinding in the absence of normal pathways and impulse activity.	retinal axons were challenged to grow to their targets both along abnormal pathways and in the absence of impulse activity. eye primordia were first transplanted from normal to ectopic sites in axolotl embryos. most of the hosts were genetically eyeless, others were enucleated normal embryos. these axolotl embryos were then parabiotically joined to california newt embryos. both operations were completed by stage 28, which is before axons have left the eye. the result of the parabiosis was a para ...	1984	6325605
distribution of desmosomal components in the tissues of vertebrates, studied by fluorescent antibody staining.	in previous work we used immunofluorescent staining with specific antibodies to study the distribution of five desmosomal antigens in the epithelia of different vertebrate animals. we showed that all five antigens were present in all epithelia studied in human, bovine, rat, guinea pig, chick and frog (rana pipiens) tissues. it was concluded that desmosomes are highly conserved structures. this paper extends those studies: by including three other species, a lizard (lacerta viridis), the axolotl ...	1984	6378940
different modes of pronephric duct origin among vertebrates.	it is possible to distinguish differences in pronephric duct morphogenesis by using scanning electron microscopy to observe the results of blocking, marking and grafting experiments as well as the normal course of development. here we compare the mode of pronephric duct development in embryos representing three orders of vertebrates: birds (class, aves; order, gallus); frogs (class, amphibia; order, anura); and salamanders (class, amphibia; order, urodela). the axolotl (a urodele) pronephric duc ...	1984	6740242
difference of the in vivo responsiveness to thyrotropin stimulation between the neotenic and metamorphosed axolotl, ambystoma mexicanum: failure of prolactin to block the thyrotropin-induced thyroxine release.	basal and tsh-induced plasma concentrations of t4 have been measured by radioimmunoassay in the neotenic and metamorphosed male axolotl ambystoma mexicanum both before and after an ovine prolactin pretreatment. all injections are made into the vena abdominalis. basal levels of t4 are low in neotenes (85 +/- 19 pg/ml) and somewhat higher in metamorphosed ambystoma (171 +/- 39 pg/ml), but are increased during metamorphosis (1094 +/- 138 pg/ml). following injection of 5 mu bovine tsh circulating le ...	1984	6510692
common mechanisms in vertebrate axonal navigation: retinal transplants between distantly related amphibia.	embryonic eye primordia were transplanted from the anuran, xenopus laevis, to the urodele, ambystoma mexicanum, in order to assess whether retinal axons of one species could grow to appropriate central targets in a distantly related species. to trace the early retinal projections, xenopus primordia were removed, incubated for 20 min in a solution containing [3h]proline, washed, and then transplanted to host axolotl embryos. genetically eyeless hosts were used in some of the experiments so that t ...	1984	6536722
perpendicular orientation and directional migration of amphibian neural crest cells in dc electrical fields.	the behavior of cultured neural crest cells of ambystoma mexicanum and xenopus laevis in dc electrical fields was studied. in fields of 1-5 v/cm, isolated or confluent cells retract both their anode- and cathode-facing margins. subsequently, the cells elongate, with protrusive activity confined to their narrow ends. in larger fields (greater than or equal to 5 v/cm), protrusions form on the cathode-facing sides of the perpendicularly oriented cells. the cells then begin migrating laterally, perp ...	1984	6582473
the response of denervated axolotl arms to delayed amputation.	forearms of juvenile axolotls can be kept denervated for up to 4 weeks by deflecting brachial nerves to the flank. a more orthodox second denervation prolongs this state up to a total of six weeks. the denervated arms are unable to regenerate for the whole period, but eventually become reinnervated and then regenerate normally. these results and analogous experiments on adult newts prompt a partial retraction and reinterpretation of my previous report on regeneration after prolonged denervation.	1984	6533253
the cellular contributions of blastema and stump to 180 degrees supernumerary limbs in the axolotl.	by inverting triploid blastemas onto diploid stumps (and vice versa) the cellular contributions to supernumerary limbs so generated have been assessed. the four classes of 180 degrees supernumerary limbs each had a different mixture of stump and blastemal cells. the mesoderm of normal supernumeraries was composed entirely or almost entirely of stump cells and were always of stump handedness. the mesoderm of symmetrical supernumeraries was of variable composition, it could be mostly stump, mostly ...	1984	6533251
accumulation and localization of troponin-t in developing hearts of ambystoma mexicanum.	troponin-t (tn-t) expression in developing hearts of axolotls, ambystoma mexicanum, was studied with the use of polyclonal and monoclonal antibodies and sds-polyacrylamide gel electrophoresis. in precontractile hearts (stage 32/33), tn-t was present in addition to myosin, actin and tropomyosin as evidenced by the presence of the protein bands in sds-gels and by indirect immunofluorescence. tn-t was localized in amorphous collections at the peripheries of these precontractile cells. hearts of nor ...	1984	6442732
the distribution of marked dermal cells from small localized implants in limb regenerates.	numerous experiments have demonstrated that skin has a profound influence on the pattern of limb regeneration in urodeles. in this investigation, the fate during regeneration of marked cells derived from narrow strips of skin inserted into different positions around the limb circumference has been followed. skin strips were taken from triploid axolotls and transplanted into diploid sibling animals. the distribution of trinucleolate cells was determined at the site of amputation and in the regene ...	1984	6389219
anchoring filaments of the amphibian epidermal-dermal junction traverse the basal lamina entirely from the plasma membrane of hemidesmosomes to the dermis.	an electron microscopical study of the epidermal-dermal junction in the axolotl and adult rana pipiens has been carried out. this shows that filaments of about 12nm in diameter, known as anchoring filaments, pass from the hemidesmosomes at the base of the epidermal cells across the basal lamina to the dermis. there they may unite to form broader fibres, known as anchoring fibrils, or may simply form bundles. in the axolotl, particularly, the anchoring fibrils or bundles of anchoring filaments, e ...	1984	6335885