Publications

allopurinol-induced melanism in the tiger salamander (ambystoma tigrinum nebulosum).	the enzyme, xanthine dehydrogenase (xdh), has been examined in ambystoma tigrinum nebulosum with respect to its role in pigmentation. it now seems probable that the melanoid gene (m) either codes directly for xdh or is somehow intimately connected with the normal function of this enzyme. inhibition of xdh using the drug, allopurinol, results in animals which appear to be phenocopies of melanoid mutants as described for the mexican axolotl (ambystoma mexicanum). the effects of allopurinol in term ...	1979	490138
the regression of synapses formed by a foreign nerve in a mature axolotl striated muscle.	a study has been made of the factors which determine that the terminals of a foreign flexor nerve at synaptic sites in a unrodele extensor muscle regress on return of the original extensor nerve. the quantal content (m) of the endplate potential (epp) at flexor nerve terminal synapses, during innervation of a previously denervated extensor muscle, increased in about 8 weeks to reach the same size as at normal extensor nerve terminals; the same time was taken for m to reach normal size at extenso ...	1979	487102
maintenance of growth- and thyroid-stimulating properties of ectopic pituitaries in the mexican axolotl (ambystoma mexicanum).		1979	467973
chloride-dependent sodium transport in the skin of ambystoma mexicanum [proceedings].		1979	458718
duplicated axolotl regenerates.	three series of palette stage regenerates were prepared by amputating both arms of juvenile axolotls in the mid-forearm, above the elbow, or close to the shoulder. within each series, excised regenerates were replaced in their original orientation (as a control) or rotated at 90 degrees intervals about the proximodistal axis, or were transplanted to the contralateral arm with identical rotations. control grafts occasionally caused the formation of a single extra digit. all experimental rotations ...	1979	448271
development of synaptic connections between different segmental motoneurones striated muscles in an axolotl limb.		1979	446887
normal anterior endoderm corrects the heart defect in cardiac mutant salamanders (ambystoma mexicanum).	recessive mutant gene c in axolotl embryos results in an absence of heart function. normal (+/+) anterior endoderm cultured with mutant (c/c) hearts totally corrects the defect.	1979	441740
morphogenetic interactions occurring between blastemas and stumps after exchanging blastemas between normal and double-half forelimbs in the axolotl, ambystoma mexicanum.		1979	437319
axon reflexes in axolotl limbs: evidence that branched motor axons reinnervate muscles selectively.		1979	428494
experimental studies on a mutant gene, a, causing albinism in the axolotl, ambystoma mexicanum.		1978	414944
role of tropomyosin in actin filament formation in embryonic salamander heart cells.	recessive mutant gene c in ambystoma mexicanum embryos causes a failure of the heart to function even though initial heart development appears normal. an analysis of the constituent proteins of normal and mutant hearts by sds-poly-acrylamide gel electrophoresis shows that actin (43,000 daltons) is present in almost normal amounts, while myosin heavy chain (200,000 daltons) is somewhat reduced in mutants. both sds-polyacrylamide gel electrophoresis and immunofluorescence studies reveal that tropo ...	1979	383724
regenerative responses in larval axolotl limbs with skin grafts over the amputation surface.	complete flaps of whole skin over the amputation surface of larval axolotl limbs did not prevent dedifferentiation, dna synthesis, and mitosis. however, even by two weeks, insufficient cell division had occurred for blastema formation. in about 50% of the cases, small areas of wound epidermis formed over the amputated tip of the radius or ulna. at two weeks after amputation, mitotic figures and dedifferentiated cells which incorporated h3-thymidine were predominantly located in the vicinity of t ...	1979	381569
myogenesis and inductive processes during heart development in mexican axolotls (ambystoma mexicanum).		1978	367464
identification by immunofluorescence of prolactin- and somatotropin-producing cells in the pituitary gland of the mexican axolotl (ambystoma mexicanum, shaw).	the indirect immunofluorescence procedure was used to identify prolactin (lth)-and somatotropin (sth)-producing cells in the pituitary of the mexican axolotl. histological staining techniques were employed to corroborate immunocytological results. the lth cells are large, orange-staining cells (acidophils 1) distributed in the posterior two-thirds of the pars distalis. the sth cells are small, erythrosinophilic elements (acidophils 2) principally concentrated in the dorsal part of the pars dista ...	1978	365348
effect of temperature on transplantation immunity in ambystoma mexicanum.	juvenile and mature neotenous ambystoma mexicanum received allogeneic and xenogeneic skin transplants. rejection times for 1st-set, and 3rd-set grafts were noted at 21 degrees c, and for axolotls placed in a cold-room at 7 degrees c 7 h post-grafting, 1 week post-grafting and 2 weeks post-grafting respectively. in all cases graft-rejection was chronic; 2nd and 3rd-set grafts were rejected progressively more rapidly than 1st-set grafts. an important temperature-sensitive event occurs during the 1 ...	1978	357221
the role of grafted skin in the regeneration of x-irradiated axolotl limbs.		1977	320068
ketogenesis in vertebrate livers.	1. the hypothesis is advanced that a gluconeogenic organ such as the liver would evolve to oxidise fatty acids as its source of atp for gluconeogenesis. it is also argued that such an organ might, in the light of current knowledge, be expected to be ketogenic. the animals investigated were lamprey, rainbow trout, eel, toad, axolotl, lizard and rat. 2. the respiratory quotients of liver slices from all animals was close to 0.74. ketone bodies were produced from butyrate by all livers excepting th ...	1977	318434
distribution and homologies of subunits in the ldh isoenzyme pattern of urodeles.	1. the subunit distribution and homologies of ldh isoenzymes are investigated in the species triturus vulgaris, cristatus, alpestris and helveticus, and ambystoma mexicanum by means of immunoprecipitation and starch gel electrophoresis. 2. fresh tissue extracts contain the following patterns: (a) trit. vulgaris--two isoenzymes: the m4 and h4 tetramers. no hybrid formation is observed between h and m subunits. (b) trit. cristatus--two isoenzymes: the m4 and h4 tetramers. occasional hybrid formati ...	1978	318283
role of thyroid hormones in the normal and glucocorticosteroid hormone-induced evolution of carbamoyl-phosphate synthase (ammonia) activity in axolotl liver.	1. in axolotl liver, the activity of carbamoyl-phosphate synthase (ammonia), expressed per mg liver protein, decreases to a minimum at 5 months of age, then increases to a maximum at 8 months of age which is followed by a decrease again. the initial decrease between 3 and 5 months of age appears to be largely due to an increase in non-carbamoyl-phosphate synthase protein and the following increase between 5 and 8 months of age to a relative increase of carbamoyl-phosphate synthase protein. 2. tr ...	1978	318276
high density cell water in amphibian eggs?	the exchange of isotopic water, 2h2o and h2(18)o has been studied in amphibian eggs. the experiments were carried out with ovarian and body cavity eggs of rana temporaria and unfertilized eggs of ambystoma mexicanum. the cytoplasmic diffusion coefficient for h2(18)o was found to be 4.6 x 10(-6) cm2/s, somewhat higher than that for 2h2o, 3.4 x 10(-6) cm2/s. the total change in reduced weight, delta rw, during the isotope experiments was compared with the total amount of water in the egg cell, m. ...	2000	317089
thymus independent anti-horse erythrocyte antibody response and suppressor t cells in the mexican axolotl (amphibia, urodela, ambystoma mexicanum).	anti-horse erythrocyte (anti-hrbc) antibody synthesis was studied in normal, early thymectomized and adult thymectomized axolotls. the kinetics of the responses were similar to those described in the same species for antibody synthesis against bacterial or viral antigens. booster injections did not induce any characteristic anamnestic responses. early and adult thymectomized axoltls gave in three experimental groups higher anti-hrbc responses than controls. it is concluded that hrbc acts in the ...	1979	312266
quantitive studies of the reactions to horizontal angular accelerations in axolotls. ii. head-turning reflexes in animals with a supernumerary pair of labyrinths.	in axolotls (ambystoma mexicanun) the labyrinths and the associated parts of the medulla were doubled artificially. in these so-called tandem-heads the vestibular afferent fibres from both labyrinths on one side united within the medulla to form common bundles. the head-turning reflexes following impulse acceleration and during long-lasting acceleration were measured quantitatively and compared with those for normal animals. the form and the time-course of the reactions were almost identical in ...	1977	300773
target recognition in neurogenesis: formation of the mauthner axon cap.	to learn whether presence of a specific neuron, the mauthner (m) cell, is required for the organization, during embryogenesis, of an associated synaptic neuropil, the m-axon cap, m-cell precursors were experimentally deleted in embryos of the zebra fish (brachydanio rerio) and the axolotl (ambystoma mexicanum). examination of early larvae revealed that in about half of the cases m-axon caps were present in the absence of the corresponding m-cells. the locations and structures of such caps were a ...	1979	291997
multiple melanomas in the axolotl ambystoma mexicanum.	multiple melanophoromas in the axolotl ambystoma mexicanum were characterized by cell anaplasia and polymorphism. pigment spots may be the first stage of tumor development.	1979	286820
re-innervation of axolotl limbs. ii. sensory nerves.		1975	237288
re-innervation of axolotl limbs. i. motor nerves.		1975	237287
suppression of foreign innervation in axolotl muscle may not be dependent on juxtaposition of native and foreign nerve terminals.	the posterior supracoracoideus nerve of the axolotl, ambystoma mexicanum, was induced to make synapses outside its normal muscle territory. muscle fibres with inputs from both native and foreign nerves were studied during the period of suppression of foreign transmission and in only 8% of fibres were foreign and native terminals found within 120 micrometer of each other. a combined cholinesterase/silver staining technique revealed non-innervated endplates in foreign-innervated fibres just prior ...	1979	223086
ionic mechanism for the generation of horizontal cell potentials in isolated axolotl retina.	the ionic mechanism of horizontal cell potentials was investigated in the isolated retina of the axolotl ambystoma mexicanum. the membrane potentials of both receptors and horizontal cells were recorded intracellularly while the ionic composition of the medium flowing over the receptor side of the retina was changed. the membrane potential of the horizontal cell is highly depender side of the retina was changed. the membrane potential of the horizontal cell is highly dependent on the extracellul ...	1988	202664
the formation and regression of synapses during the re-innervation of axolotl striated muscles.	1. a study has been made of the formation and regression of synapses formed by spinal nerves 16 and 17 in axolotl hind-limb flexor muscles following the severing of nerve 16, using histological, ultrastructural and electrophysiological techniques. 2. axolotl hind-limb flexor myofibres possessed 'en plaque' end-plates from either spinal nerve 16 or 17 or both at intervals of about 1000 micronm along their length; the myofibre's length constant was about 700 micronm allowing electrophysiological o ...	1977	191597
the hormonal regulation of urea excretion in the mexican axoloti (ambystoma mexicanum cope).		1977	188719
the intracellular localization of carbamoyl-phosphate synthase (ammonia) activity in the liver of the mexican axolotl, ambystoma mexicanum (shaw).		1976	183934
three muscle fibre types in the axial muscle of axolotl (ambystoma mexicanum shaw): a quantitative light- and electron microscopic study.	morphometric analysis by light microscopy of p-phenylene-diamine stained semithin sections of axolotl tail muscle revealed differences in the cross-sectional area of the fibres and in the number of mitochondria and of lipid inclusions per fibre, and indicated the presence of three distinct types of fibres. the tripartition was found to be statistically highly significant. representative fibres from each group established by light microscopic morphometry were subjected to an ultrastructural morph ...	1996	178448
[meiosis: role of a histone kinase in the condensation of ovarian oocyte chromosomes of xenopus laevis and ambystoma mexicanum].	by injecting heterologous histone-kinase preparations into ovarian axolotl oocytes, it has been possible to speed up the progesterone-induced process of chromosome condensation. moreover, in some instances, this condensation and even complete maturation have been obtained after injection of protein kinase alone, thus in the absence of hormone stimulation. two different histone kinase preparations have been used: one was prepared from ascites cell chromatin and the other from in vitro ovulated xe ...	1975	177222
[oxygen consumption and cytochrome oxidase activity of muscle tissue from the limbs of axolotls following restoration of regenerative capability suppressed by x-ray irradiation].	the intensity of oxygen consumption and the activity of cytochrome oxidase have been studied in the homogenate, mitochondria and nuclei of the limb muscle tissue in axolotls after the suppression of regenerative ability by x-irradiation and its experimental restoration. under the suppression of regenerative ability, the oxygen consumption was inhibited. the cytochrome oxidase activity in the homogenate and mitochondria decreased and in the nuclei remained at the same level or even increased as c ...	1975	175338
stretch receptors in urodele limb muscles.	non-encapsulated, fine beaded nerve endings were found histologically on some muscle fibres in a number of limb muscles in newts and axolotls. they were present in newt muscles that had been chronically de-efferented, and in which no efferent activity survived, and were therefore likely to be sensory. they were located only on muscle fibres on or near the outside surface of the muscle. these small-diameter muscle fibres were characterised histochemically by low lipid, sdh and phosphorylase conte ...	1976	129283
[invariability of the h-y antigen expression in the heterogametic sex of some amphbians and evidence for sexual dimophrism of the antigen expression in pelodytes punctatus d (amphibia, anura)].	the h-y antigen is studied in some amphibians whose sexual genetic constitution is known. thus, in pelurodeles waltlii, ambystoma mexicanum, xenopus laevis and rana ridibunda, the invariability of the h-y antigen expression in the heterogametic, sex is confirmed. in pelodytes punctatus the genetic sex is unknown but the existence of the h-y antigen in phenotypic males leads to the conclusion of a male heterogamety of the xy type.	1979	121269
delayed hypersensitivity in ambystoma mexicanum.		1979	113261
[experimental studies on the symmetry reaction of axolotl oocytes and eggs: factors affecting the early appearance of the grey crescent following heat shock].	a heat-shock (36.8 degrees c for 10 min.) can induce the immediate appearance of the grey crescent in a high proportion of freshly laid fertilised or artificially activated axolotl eggs, but only if that shock occurs within 1 h 30 min. following deposit of eggs (at 18 degrees c) and if eggs are not dejellied. on non-activated virgin eggs, the heat-shock is efficient during at least 3 hrs. this symmetry reaction can be induced on in vitro artificially matured oocytes, still protected by follicula ...	1979	111864
an sem and tem study of suppression of eye development in eyeless mutant axolotls.	morphology of the primary optic rudiment of normal eyed and mutant eyeless (e/e) axolotl embryos was studied at light. tem and sem levels. the presumptive eyeforming region of eyeless embryos differs from that of normal embryos in several important respects including premature formation of basal lamina, separation from overlying ectoderm by mesenchyme cells and persistence of granules in the interspace surrounding the optic anlage into relatively late developmental stages. these differences sugg ...	1979	110173
induced metamorphosis in ambystoma mexicanum: lack of effect of triiodothyronine on tissue or blood levels of thyrotropin-releasing hormone (trh).		1998	105962
[effect of valinomycin on mitotic activity and ciliary movement during embryonic development].	the k+ ionophore valinomycin very quickly arrests cleavage in sea urchin and mouse eggs at concentrations ranging between 10 and 3 micron. development of axolotl and xenopus eggs is not arrested before the blastula or gastrula stage. the motility of sea urchin sperm, blastulae and gastrulae is suppressed, within a few minutes, by 1-9 micron valinomycin.	1978	96956
on the differentiation of prospective ectoderm to a ciliated cell pattern in embryos of ambystoma mexicanum.	the differentiation of the ectoderm in ambystoma mexicanum (harrison stage 26--27) was examined under in vivo and in vitro conditions by scanning electron microscopy under different experimental conditions. about one out of three flank epidermal cells was found to be ciliated in the undistrubed or control embryos. the shape of ciliated cells in the explants from the animal region was only slightly affected. in no case was it possible to find two adjacent ciliated cells, implying that these cells ...	1977	73569
morphological and functional aspects of the arrangement of connective tissue and muscle fibres in the tail of the mexican axolotl, siredon mexicanum (shaw) (amphibia, urodela).	in the lateral musculature of the axolotl tail a multipennate arrangement of muscle fibres is found in the 3rd postanal myomere and all following myomeres. this arrangement appears in larval stages as soon as the myomeres concerned are fully differentiated. within a myomere a uniform degree of contraction of the muscle fibres may be achieved either by helical arrangement as seen in teleosts, by diminishing fibre length in medial direction or by a combination of both phenomena. the relation betwe ...	1977	67739
an autoradiographic study of optic fiber projections from eye grafts in eyeless mutant axolotls.		1977	67046
[effect of prolactin on mucous epidermal cells in the intact and hypophysectomized axolotl].		1975	54279
electrophysiological experiments on the mechanism and accuracy of neuromuscular specificity in the axolotl.	the supracoracoideus muscle of the axolotl shoulder girdle is innervated by two nerves, the supracoracoideus nerve (sc) supplying most of the muscle and the posterior supracoracoideus (psc) supplying the posterior corner. all the muscle fibres are multiply innervated and at the border between the two innervations many muscle fibres, when penetrated by a microelectrode, show junction potentials from both nerves. in such cases one junction potential is often very small, below the threshold for exc ...	1977	19787
spontaneous release of transmitter from 'repressed' nerve terminals in axolotl muscle.		1977	18677