Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| axial characteristics of nerve induced supernumerary limbs in the axolotl. | supernumerary limbs were produced by deviating the sciatic nerve to the surface of the axolotl hindlimb either alone or in combination with small skin grafts from specific limb positions. with no skin grafts a very low frequency of good supernumeraries were produced. however, when associated with skin grafts, this frequency was significantly increased. the pattern of skeletal elements and muscles were analysed in the supernumeraries which formed at each location. in both the anterior-posterior a ... | 1984 | 28305105 |
| xanthophores in chromatophore groups of the premigratory neural crest initiate the pigment pattern of the axolotl larva. | the barred pigment pattern (lehman 1957) of the axolotl larva is best observed from stage 41 onwards, where it already consists of alternating transverse bands of melanophores and xanthophores along the dorsal side of the trunk. the present study investigateswhen the two populations of neural crest derived chromatophores, melanophores and xanthophores become determined andhow they interact to create the barred pigment pattern. the presence of phenol oxidase (tyrosinase) in melanophores (revealed ... | 1984 | 28305101 |
| is the na+,k+-atpase symmetrically distributed in the neuroepithelium of the vestibular system in the axolotl (ambyostoma mexicanum)? | this study was undertaken to assess the localization of the na+,k+-atpase in the neuroepithelial cells of the macula sacculi. in vitro perilymphatic (basolateral) perfusion with ouabain produced a significant drop in the membrane potential. endolymphatic (apical) application of ouabain had practically no effect on membrane potentials. this suggests that na+,k+-atpase is asymmetrically distributed in the neuroepithelial cells. | 1984 | 6151945 |
| off-pathway synaptic transmission in the outer retina of the axolotl is mediated by a kainic acid-preferring receptor. | intracellular recordings were made from off-centre bipolar cells and horizontal cells in the superfused axolotl retina eyecup preparation. bath-applied (+/-)cis-2,3-piperidine dicarboxylic acid (pda), gamma-d-glutamylglycine (dgg), l-glutamic acid diethyl ester (gdee), (+/-)2-amino-5-phosphonovaleric acid (2-apv) and magnesium ions were assessed as antagonists of the actions of the photoreceptor transmitter. the rank order of antagonist efficacy was pda greater than dgg greater than greater than ... | 1984 | 6093015 |
| skin glands in the axolotl: the creation and maintenance of a spacing pattern. | the morphogenesis of skin glands in the larval axolotl is described at the light microscope level. the glands are derived from the epidermis, but are eventually located in the dermis. the glands are non-randomly arranged within the skin and the spacing pattern tends towards a hexagonal array in two dimensions. analysis of the spacing pattern in animals of different sizes reveals that a clear relationship exists between gland size and the distance between glands. occasionally, new small glands ar ... | 1984 | 6716048 |
| genetic mapping in the mexican axolotl, ambystoma mexicanum. | in the mexican axolotl, ambystoma mexicanum, gynogenetic diploids can be produced by suppressing the release of the second polar body in eggs activated with irradiated sperm. if the female is heterozygous for a particular mutation, some of the progeny will be homozygous for the mutation. the proportion depends on the distance from the centromere and can be used to determine the gene--centromere (or gene-kinetochore) distance. the mapping function is based on the neurospora tetrad mapping functio ... | 1984 | 6704787 |
| discovery and initial characterization of a new conditional (temperature-sensitive) maternal effect mutation in the axolotl. | the discovery of a new temperature-sensitive maternal effect mutation in ambystoma mexicanum is described. the new gene (ts-1) was recognized when 100% of the eggs spawned by homozygous females failed to develop past early gastrulation when reared at 25 degrees c. eggs raised at 10 degrees c developed normally to sexual maturity. a temperature-sensitive period during blastulation was identified by a preliminary series of temperature shifts. histologic examination revealed that nuclear abnormalit ... | 1984 | 6734988 |
| neural crest cell behavior in white and dark larvae of ambystoma mexicanum: differences in cell morphology, arrangement, and extracellular matrix as related to migration. | melanocytes of white (d/d) larvae of the mexican axolotl (ambystoma mexicanum) are confined to the dorsal midline of the trunk region, whereas in dark (d/-) larvae they are spread laterally on the flank as well, where they contribute to the normal pigment pattern of the trunk. pigment cell migration in the subepidermal space of white larvae is inhibited by the white epidermis (dalton '50; keller et al., '82). the present scanning electron microscopic study describes a well-defined sequence of ch ... | 1984 | 6699590 |
| neural crest cell behavior in white and dark larvae of ambystoma mexicanum: time-lapse cinemicrographic analysis of pigment cell movement in vivo and in culture. | the pattern of migration and motile activity of developing pigment cells of the mexican axolotl, ambystoma mexicanum, were analyzed by time-lapse cinemicrography in vivo and in culture. in vivo, melanocytes of dark (d/-) larvae migrate from dorsal to ventral in a highly directional manner. they are elongated and aligned parallel to the direction of migration. nearly all protrusive activity occurs at their ventral, leading edges. translocation occurs at a mean rate of 0.7 micron/min and involves ... | 1984 | 6699589 |
| calmodulin during development and metamorphosis in urodelan amphibians. | calmodulin isolated and purified to homogeneity from young larvae is very similar to that obtained from adult pleurodeles waltlii and these proteins are almost identical to previously described vertebrate calmodulins. during p. waltlii development, an increase in total individual calmodulin content is observed after the heart beating stage. in dorsal axial muscle, calmodulin level which is very high at the beginning of larval life (premetamorphosis) decreases strikingly in the first part of prom ... | 1984 | 6537929 |
| cellular contribution to supernumerary limbs resulting from the interaction between developing and regenerating tissues in the axolotl. | the relationship between limb development and limb regeneration is considered with regard to the mechanisms by which pattern is established during limb outgrowth. in a previous paper (muneoka, k. and bryant, s. v. 1982 nature (london) 298, 369-371) the interaction between cells from the developing limb bud and the regenerating limb blastema was found to result in the production of organized supernumerary limb structures. in this paper the relative cellular contribution from developing and regene ... | 1984 | 6468758 |
| cellular contribution to supernumerary limbs in the axolotl, ambystoma mexicanum. | using the triploid cell marker, the cellular contribution from graft and stump to the supernumerary limbs which result from controlateral grafts of limb buds and regeneration blastemas in the axolotl has been analyzed. grafts were made so as to appose anterior and posterior limb positions. overall, the contribution from graft and stump tissue was found to be approximately equal although the position of the boundary between the two was variable from limb to limb. this result is consistent with mo ... | 1984 | 6468757 |
| improved techniques for use of the triploid cell marker in the axolotl, ambystoma mexicanum. | techniques for using the triploid cell marker for studying cell lineage during the development and regeneration of the axolotl limb are described. triploid animals possess cells with three nucleoli while diploid animals possess cells with two nucleoli. we have developed a technique for isolating the limb dermis as a sheet of cells for whole-mount analysis of cellular ploidy. whole-mount tissue preparations as well as paraffin-embedded sectioned tissues were stained specifically for nucleoli with ... | 1984 | 6205921 |
| regeneration of surgically created mixed-handed axolotl forelimbs: pattern formation in the dorsal-ventral axis. | the regeneration of surgically created mixed-handed limb stumps is examined in the axolotl. operations were performed in the lower arm and upper arm regions and grafts were allowed to heal for approximately one month prior to amputation or were amputated immediately. in the lower arm group both anterior and posterior limb halves were inverted, whereas only posterior halves were inverted in the upper arm group. almost all the limbs regenerated were normal in the anterior-posterior axis, whereas a ... | 1984 | 6491582 |
| a voltage-gated hydrogen ion current in the oocyte membrane of the axolotl, ambystoma. | membrane currents in the immature oocyte of the urodele amphibian ambystoma were studied using the two-micro-electrode voltage-clamp technique. a current carried by h ions (ih) constituted the major portion of outward current activated by depolarizations from the resting voltage (about -60 mv). net inward current was not observed at this developmental stage. the reversal potential for ih measured from tail currents obtained in two step voltage-clamp experiments shifted by 54 mv per unit change i ... | 1984 | 6086909 |
| retinoic acid-induced pattern duplication in regenerating urodele limbs. | the effects of varying doses of retinoic acid on forelimb regeneration in larval ambystoma mexicanum amputated through the wrist joint and in adult notophthalmus viridescens amputated through the basal carpals were compared. in both species, the major effect of retinoic acid was to cause the proximodistal duplication, in the regenerate, of stump segments proximal to the amputation plane. transverse axial duplications (anteroposterior and dorsoventral) occurred in a smaller percentage of cases; t ... | 1984 | 6724131 |
| the pigmentary system of developing axolotls. ii. an analysis of the melanoid phenotype. | the melanoid mutant in the mexican axolotl (ambystoma mexicanum) is analysed with respect to the differentiation of pigment cells. pigment cells were observed with the transmission electron microscope in order to determine any unusual structural characteristics and to determine what happens to each of the cell types as development proceeds. chemical analysis of pteridine pigments was also carried out, and changes in pteridine biosynthesis were found to correlate well with changes in xanthophore ... | 1984 | 6470606 |
| the pigmentary system of developing axolotls. i. a biochemical and structural analysis of chromatophores in wild-type axolotls. | a biochemical and transmission electron microscopic description of the wild-type pigment phenotype in developing mexican axolotls (ambystoma mexicanum) is presented. there are three pigment cell types found in adult axolotl skin - melanophores, xanthophores and iridophores. both pigments and pigment cells undergo specific developmental changes in axolotls. melanophores are the predominant pigment cell type throughout development; xanthophores occur secondarily and in fewer numbers than melanopho ... | 1984 | 6470605 |
| in vitro development of isolated ectoderm from axolotl gastrulae. | the development of ectoderm isolated from the animal pole of axolotl gastrulae is monitored by light microscopy, electron microscopy and analysis of newly synthesized proteins, glycoproteins and glycolipids. when control embryos are undergoing neurulation it is shown that the explants autonomously begin to express epidermal markers and do not express mesodermal markers. however the results suggest that not all the cells become epidermal and electron microscope examination shows that only the out ... | 1984 | 6747530 |
| regional biosynthetic markers in the early amphibian embryo. | a search has been made for regional differences in macromolecular synthesis in the axolotl embryo at a stage when the principal regions have become determined but terminal differentiation has not yet begun. the epidermis of the neurula makes a number of abundant proteins which are not made elsewhere. some of these are identified by immunoprecipitation as cytokeratins (relative molecular masses (mr) 62,59,54,51 and 46 x 10(3)). at the same stage a network of tonofilaments becomes visible by elect ... | 1984 | 6747529 |
| a quantitative analysis of regeneration from chimaeric limb stumps in the axolotl. | we have analysed the cellular contribution and cellular displacement which occur during regeneration from chimaeric (half triploid, half diploid) lower arms in the axolotl. in general both anterior and posterior halves contribute approximately 50% of the regenerated limb cells. deviations from equal contribution were observed only when anterior tissue was grafted, suggesting that anterior tissue is more sensitive to grafting operations. approximately 25% of all cells in the regenerated limb were ... | 1985 | 3834023 |
| molecular duality of dna ligase in axolotl corresponds to distinctive transcriptional information. | based upon the use of specific antibodies and sucrose gradient sedimentation analysis, the present work describes the use of the post-transcriptional equipment of the urodele egg to compare the information contained in two rna samples extracted from respectively liver and activated axolotl eggs. it is shown that besides the normal dna ligase activity present in the host pleurodeles eggs, rna can translate for the specific carried information revealing a difference between the two samples. moreov ... | 1985 | 4054231 |
| regional specificity of glycoconjugates in xenopus and axolotl embryos. | this paper reviews work on the presence, synthesis and developmental regulation of glycoconjugates (proteoglycans, glycoproteins and glycolipids) in the early amphibian embryo. in the axolotl there is little regional specificity of protein synthesis until the tailbud stage, but substantial regional specificity of glycoprotein synthesis from the end of gastrulation. glycolipid synthesis is more uniform although a number of unique species are made in the epidermis. isolated explants from axolotl e ... | 1985 | 3913731 |
| towards understanding paternal extragenic contributions to early amphibian pattern specification: the axolotl ts-1 gene as a model system. | as a model system for understanding the role sperm extragenic components might play in early embryogenesis the genetics and phenotype of the ts-1 axolotl (ambystoma mexicanum) mutant gene are reviewed. that mutant gene displays parental effects. it exhibits both maternal (egg-mediated) as well as paternal (sperm-mediated) phenotypic effects. a variety of possible modes of action of the ts-1 gene are reviewed. comparisons of various precedents to the ts-1 genetic data are made. in addition, novel ... | 1985 | 3841668 |
| embryonic induction and cation concentrations in amphibian embryos. | explanted ectoderm from early gastrulae of triturus alpestris was treated with the na-k ionophore gramicidin (10(-9) to 10(-5) m) and the ca-ionophore a 23187 (10(-7) to 10(-5) m). the ectoderm developed almost exclusively to atypical epidermis as in the control explants. when the ectoderm was treated with ouabain (10(-4) m), intracellular na+ increased about 4.4-fold and k+ was reduced by half. mesenchyme cells in small number differentiated in about 40% of the ouabain-treated explants. the tim ... | 1985 | 2416476 |
| an analysis of protein synthesis patterns during early embryogenesis of the urodele--ambystoma mexicanum. | changes in protein synthesis during early ambystoma mexicanum (axolotl) embryogenesis were monitored using two-dimensional (2-d) polyacrylamide gel electrophoresis. no change in synthesis patterns during progesterone-induced oocyte maturation was detected. in oocytes matured in vivo (unfertilized eggs), however, the synthesis of several oogenetic proteins ceased, only to be resumed later in development. at fertilization, one novel non-oogenetic protein was found. a cleavage-specific protein was ... | 1985 | 4093754 |
| regeneration from isolated half limbs in the upper arm of the axolotl. | a technique enabling the isolation of half limb stumps using strips of skin from the head is described. using this technique posterior, dorsal and ventral halves of the upper arms of axolotls were constructed. all halves produced regenerates and regional differences were shown in the regenerative and regulative abilities of the different halves. posterior half stumps regenerated limbs with a mean digit number of 3.9 and had a normal dorsoventral muscle pattern. anterior halves produced hypomorph ... | 1985 | 4093751 |
| a three-step scheme for gray crescent formation in the rotated axolotl oocyte. | it has been shown that various inhibitors of protein synthesis can elicit the precocious appearance of a gray crescent (gc) in in vitro maturing, nonactivated ambystoma mexicanum oocytes. however, evidence has now been obtained that these treatments fail 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 the injection of ... | 1985 | 4007261 |
| histological analysis of limb regeneration in postmetamorphic adult ambystoma. | previous investigation into the regenerative ability of postmetamorphic adult land phase ambystoma has revealed that these species have the capacity to completely regenerate a limb, given optimal environmental conditions, and the gross morphological characteristics of limb regeneration in these species compared favorably with the external regeneration morphology of aquatic phase forms. the present study concerns a histological and histochemical examination of the regenerating limb tissues and th ... | 1985 | 3842040 |
| peanut lectin receptors in the early amphibian embryo: regional markers for the study of embryonic induction. | the regional and temporal specificity of peanut agglutinin binding was determined for early amphibian embryos. with the onset of neurulation, a receptor appears on the epidermis, but remains absent from the neural plate. a second type of receptor, largely masked by sialic acid, appears throughout the extracellular matrix. in the axolotl, the epidermal receptor is epimucin and the matrix receptor is fibronectin plus other components. both receptors are autonomously expressed, on schedule, by appr ... | 1985 | 3995583 |
| cellular behavior in the anteroposterior axis of the regenerating forelimb of the axolotl, ambystoma mexicanum. | cellular behavior along the anteroposterior axis of the regenerating axolotl forelimb was studied by use of triploid (3n) tissue grafted into diploid (2n) hosts and three-dimensional computer reconstructions. asymmetrical upper forelimbs were surgically constructed with one half (anterior or posterior) 3n and the other half 2n. limbs were amputated immediately after grafting or were permitted to heal for 5 or 30 days prior to amputation. when regenerates had attained the stage of digital outgrow ... | 1985 | 3987961 |
| regeneration of axolotl hindlimbs bearing surgically created discontinuities in the anterior-posterior axis. | the pattern regulation process in amphibian limbs has been examined with respect to the presence of discontinuities in the anterior-posterior (a-p) axis. limbs bearing such discontinuities were surgically created by contralateral exchange of either dorsal or ventral half thighs and these limbs were then amputated immediately after surgery. the results demonstrate that a-p discontinuities lead to the formation of extra limb structures during distal outgrowth in contrast to the mosaic behaviour of ... | 1985 | 4031745 |
| neural fold and neural crest movement in the mexican salamander ambystoma mexicanum. | in studies of amphibian neurulation, the terms "neural ridge," "neural fold," and "neural crest" are sometimes used as synonyms. this has occasionally led to the misconception that grafting of the neural crest is equivalent to grafting of the neural fold. the neural fold, however, is composed of three parts: the neural crest, prospective neural tube tissue, and epidermis. in order to investigate how these neural fold components move during neurulation, time-lapse photography, electron microscopy ... | 1985 | 3989498 |
| in vitro differentiation of neuronal precursor cells from amphibian late gastrulae; morphological, immunocytochemical studies, biosynthesis, accumulation and uptake of neurotransmitters. | neuronal differentiation has been studied in dissociated cell cultures from early neurulae of pleurodeles waltl and ambystoma mexicanum. cocultures were prepared from the neural primordium and underlying chordamesoderm. np and nf cultures were prepared from isolated neural plate and neural folds, respectively. neuronal precursors in np and nf cultures had distinctive aggregation properties already evident after 1-2 days in culture. after 10-15 days, mature neurones and synapses were observed by ... | 1985 | 2863321 |
| normal fates and states of specification of different regions in the axolotl gastrula. | a fate map was constructed for four regions of the early gastrula of ambystoma mexicanum using orthotopic grafts from donors labelled with fldx (fluoresceinated-lysinated-dextran). the region around the animal pole gave rise to epidermis only and did not include prospective neural plate. the dorsal marginal zone contributed to cephalic endoderm and to the whole length of the axial mesoderm (notochord and somites), the lateral marginal zone to lateroventral and somitic mesoderm, and the ventral m ... | 1985 | 2411838 |
| stimulation of initial neural crest cell migration in the axolotl embryo by tissue grafts and extracellular matrix transplanted on microcarriers. | the present experiments were designed to test whether the onset of neural crest cell migration in the embryonic axolotl trunk is stimulated by surrounding tissues and their associated extracellular matrix (ecm). tissue grafts, or embryonic ecm adsorbed in vivo onto inert "microcarriers" prepared from nuclepore filters, were placed close to the premigratory neural crest cells, and the embryos were then incubated to a specific stage. the experiments were evaluated with light microscopy, sem, and t ... | 1985 | 3972165 |
| kinetics of light-sensitive channels in vertebrate photoreceptors. | we have studied the ion channels mediating the light response of vertebrate rod photoreceptors by analysing fluctuations in the current across the rod membrane, using the whole cell patch-clamp technique on rods isolated from the axolotl retina. light decreases the membrane current fluctuations. noise analysis reveals two components to this decrease: a low frequency component due to biochemical noise in the transduction mechanism, and a high frequency component we attribute to the random opening ... | 1985 | 2579400 |
| eye enucleation and regeneration of neural retina in axolotl larvae (ambystoma mexicanum). | the eyes of axolotl larvae were enucleated at stages 30 and 37. animals with single dorsomedian eyes resulted in the first case (i.e. stage 30). when a piece of pigment epithelium was re-implanted into stage 37 animals at the site of the lesion, limited regeneration was observed when the implant formed a vesicle, but, when the pigment epithelium remained "open" regeneration of the neural retina was extensive. the possible resons for this difference was discussed. | 1985 | 4014704 |
| experimental evidence for a proteinaceous presegmental wave required for morphogenesis of axolotl mesoderm. | mesoderm of axolotl embryos at various developmental stages was briefly exposed to a calcium-free 0.01% trypsin solution by temporary removal of the epidermis. this treatment was found to disrupt somite segmentation in a localized region and the pronephric duct was unable to migrate through this region. the affected area, consisting of 3.91 +/- 1.04 somites, traveled through the embryo in synchrony with, and 3.55 +/- 0.69-somite widths ahead of segmentation. trypsinization in the presence of 340 ... | 1985 | 3965323 |
| retinoids and the control of pattern in regenerating limbs. | it has recently been discovered that, as well as having effects on cell division and differentiation, retinoids induce dramatic changes in the development of pattern in limbs. local application of retinoic acid to the anterior side of chick limb buds causes anteroposterior mirror-imaging such that the limb has six digits instead of three. in rana limb buds retinoids induce changes in both the anteroposterior and proximodistal axes. in regenerating axolotl limbs their effect is primarily on the p ... | 1985 | 3896698 |
| a model of inward and outward membrane currents in cultured embryonic amphibian spinal neurons and reconstruction of the action potential. | a model of the membrane currents in embryonic amphibian neurons has been developed in order to investigate the ionic mechanisms underlying developmental changes in excitability. differentiating amphibian neurons both in situ and in vitro show a gradual change in the ionic sensitivity of their action potential from ca- to na-dependent, with an intermediate period in which the action potential shows a mixed ionic sensitivity. the model developed incorporates quantitative descriptions of na, ca and ... | 1985 | 2422357 |
| developmental mutants isolated from wild-caught xenopus laevis by gynogenesis and inbreeding. | xenopus laevis obtained from indigenous african populations are a rich source of mutants affecting development. gynogenesis and inbreeding were used to isolate mutants affecting development from wild-caught xenopus laevis females. fourteen mutants were recovered from eight females tested. one mutant was recovered from each of two females. this load of 1.875 developmental mutants per female is similar to that found in the axolotl (ambystoma mexicanum), a urodele amphibian, and is only slightly le ... | 1985 | 3973558 |
| regulatory peptides (glucagon, somatostatin, substance p, and vip) in the brain and gastrointestinal tract of ambystoma mexicanum. | the concentrations of immunoreactive components of glucagon, somatostatin, substance p, and vasoactive intestinal polypeptide (vip) in the brain, stomach, and gut of the neotenic mexican axolotl (ambystoma mexicanum) were determined by radioimmunoassay using antibodies of defined regional specificity. the molecular forms of the immunoreactive components were analyzed by high-performance liquid chromatography (hplc). the concentrations and molecular forms of somatostatin and vip in axolotl brain ... | 1985 | 2580753 |
| motorneuron pools innervating muscles in vitamin a-induced proximal-distal duplicate limbs in the axolotl. | serially duplicated limbs containing two sets of proximal muscles were created in axolotls by vitamin a treatment. the innervation of three replicated proximal muscles was studied by using retrograde transport of horseradish peroxidase. these were the forelimb muscles biceps (seven cases) and anconeus (five cases) and the hindlimb muscle puboischiotibialis (five cases). in two cases (both of anconeus) innervation was from a correct motorneuron pool. in the other 15 cases the innervation was from ... | 1985 | 2410931 |
| a horseradish peroxidase study of motorneuron pools of the forelimb and hindlimb musculature of the axolotl. | motorneuron pools innervating axolotl limb muscles have been investigated by using the retrograde neuronal tracer horseradish peroxidase. four muscles in the forelimb (biceps, anconeus, flexor digitorum and extensor digitorum) and four functionally equivalent muscles in the hindlimb (puboischiotibialis, iliotibialis, flexor digitorum and extensor digitorum) were studied. motorneuron pools were characterized by using four criteria: position in the rostrocaudal axis; position of the median in the ... | 1985 | 2410930 |
| banding differences between tiger salamander and axolotl chromosomes. | the hoechst 33258 - giemsa banding patterns were compared on axolotl (ambystoma mexicanum shaw) and axolotl - tiger salamander (ambystoma tigrinum green) species hybrid prophase chromosomes. approximately 369 bands per haploid chromosome set were seen in the axolotl and about 344 bands in the tiger salamander. in the haploid set of 14 chromosomes, chromosome 3 has a constant short or q-arm terminal constriction at the location of the nucleolar organizer. chromosomes 14 z and w carry the sex dete ... | 1985 | 4063874 |
| formation of the pronephros and pronephric duct rudiment in the mexican axolotl. | in the mexican axolotl (ambystoma mexicanum), the pronephros begins to form at the four-somite stage. it is initially continuous with the posterior-lateral region of somite 2 and the lateral margin of somites 3 and 4. by the seven-somite stage, the pronephros has become compacted, and the cells are now morphologically distinct from the somitic cells. at this stage, a mass of loosely connected cells, apparently originating from the lateral mesoderm, is seen below somites 4 and 5. by the eight-som ... | 1985 | 29976020 |
| calcium-independent stimulation of glycogenolysis by arginine vasotocin and catecholamines in liver of the axolotl (ambystoma mexicanum) in vitro. | arginine vasotocin (avt) caused a concentration-dependent increase of glycogen phosphorylase alpha activity, breakdown of glycogen and release of glucose, when added to pieces of axolotl liver in organ culture. the concentration causing half-maximal response (ec50) was about 1 nmol/l. these actions of avt were unaffected by the adrenergic antagonists propranolol, yohimbine and prazosin, but were blocked by equimolar amounts of d(ch2)5tyr(me)avt, a synthetic antagonist of vasopressin. arginine va ... | 1986 | 3701246 |
| cyclic amp and cell differentiation in amphibian embryonic explants. | conflicting results have been published concerning the effects of cyclic nucleotides on amphibian cell differentiation. here we report the effects of cyclic adenosine monophosphate (camp) and dibutyryl-cyclic adenosine monophosphate (db-camp) on isolated explants from late blastulae of ambystoma mexicanum and xenopus laevis. both camp and db-camp (10(-4)-10(-9) m) promote 'neuralizing' differentiation in ambystoma explants. xenopus explants treated with the nucleotides (10(-4), 10(-6), 10(-8) m) ... | 1986 | 3011532 |
| behavioral development in the absence of neural activity: effects of chronic immobilization on amphibian embryos. | embryos of xenopus laevis and ambystoma mexicanum were continually immobilized from premotile stages of development to stages at which normally reared embryos were swimming well. immobilization was achieved through exposure to solutions of chloretone, lidocaine, or alpha-bungarotoxin. at a number of stages after recovery from the drugs, spontaneous and stimulated behaviors were extensively quantified. immobilization of ambystoma embryos resulted in temporary defects in musculoskeletal developmen ... | 1986 | 3711983 |
| myelin lipids: a phylogenetic study. | the lipid composition of cns and pns myelin was studied in rat, xenopus, trout and torpedo. the main difference lay in the proportion of cerebrosides, which decreased in the sequence rat greater than xenopus greater than torpedo greater than trout. in addition torpedo cns and pns myelins were extremely rich in sulfatides. in some respects, torpedo appeared closer to tetrapods than trout. otherwise the proportion of the different lipid classes did not reveal any clear evolutionary trends. the pre ... | 1986 | 3785545 |
| axolotl retina and lens development: mutual tissue stimulation and autonomous failure in the eyeless mutant retina. | during eye development in the axolotl (ambystoma mexicanum shaw), morphogenetic movements bring together tissues from head epidermis, neuroectoderm and neural crest. the stages 0 to 14 of axolotl eye development were expanded from rabl's (1898) stages 1 to 10 and correlated with harrison's (1969) stages. at the onset of neurulation (stage 13 of harrison), the head epidermis is already determined to form skin, and the neuroectoderm is committed to form brain, because these tissues develop autonom ... | 1986 | 3805980 |
| the migration of dermal cells during blastema formation in axolotls. | using the diploid/triploid cell marker in the axolotl (ambystoma mexicanum) we have examined the movement of cells from the dermis into the early limb blastema. cells of dermal origin begin to migrate beneath the wound epithelium at about 5 days postamputation, and by 10 days they are widely distributed across the amputation surface. by 15 days, a dense accumulation of blastema cells is present beneath the apical cap, and these cells are preferentially oriented in a circumferential direction. th ... | 1986 | 3792618 |
| the effect of replacing different regions of limb skin with head skin on regeneration in the axolotl. | head skin was used to replace different halves of limb skin from the upper and lower arms of axolotls. replacement of upper arm posterior skin caused the regeneration of a high proportion of single-digit limbs while replacement of dorsal, ventral or anterior skin caused only minor defects to the normal skeletal pattern. when dorsal or ventral skin was replaced, however, regenerates often lacked dorsal or ventral muscle. results from the lower arm were different in that replacement of any half of ... | 1986 | 3309120 |
| pigment cell differentiation: the relationship between pterin content, allopurinol treatment, and the melanoid gene in axolotls. | the effects of allopurinol (an inhibitor of the enzyme xanthine dehydrogenase (xdh] and the melanoid gene on pigment cell differentiation in the axolotl were examined by analyzing pigment components of the xanthophore (pterins). pterin contents of skin extracts (70% ethanol) from wild type, allopurinol-treated and melanoid axolotls were determined by thin layer chromatography (tlc) and fluorometric scanning of tlc plates. heights of peaks produced were used as a quantitative measure for pterin c ... | 1986 | 3791419 |
| dna-ligase activity in axolotl early development: evidence for a multilevel regulation of gene expression. | 1986 | 3625120 | |
| retinoic acid-binding protein in the axolotl: distribution in mature tissues and time of appearance during limb regeneration. | analysis of cytoplasmic protein preparations from axolotl tissues revealed the presence of a cytoplasmic retinoic acid-binding protein (crabp), of approximate molecular weight 17k. this protein was found to be present at various concentrations in skin, muscle, and limb tissue preparations, but not in liver and serum preparations. the distribution and molecular weight of this protein agrees with that reported in mammalian studies. the level of crabp in cone stage blastemas was found to be signifi ... | 1986 | 3019799 |
| effects of retinoids on regenerating limbs: comparison of retinoic acid and arotinoid at different amputation levels. | retinoic acid and the synthetic retinoid, arotinoid, were compared for their efficacy in inducing proximodistal (pd) pattern duplication in regenerating axolotl limbs, after amputation through either the distal zeugopodium (lower arm or leg) or distal stylopodium (upper arm or leg). at each level of amputation, the morphology of the duplications produced was the same for both retinoids, and the mean level of proximalization was dose-dependent. blastema formation was delayed by both retinoids and ... | 1986 | 28305407 |
| selective innervation of transplanted limb muscles by regenerating motor axons in the axolotl. | the segmental pattern of motor innervation of hindlimb muscles in the axolotl was studied before and after reinnervation. to ascertain the specificity of reinnervation, the four spinal nerves innervating the hindlimb were severed and allowed to regenerate. the segmental origin of axons reinnervating particular muscles was then determined by intracellular recording from muscle fibers. muscles were reinnervated in a specific manner: from the outset, the axons reinnervating each muscle originated l ... | 1986 | 3746433 |
| identification of a second type of catecholaminergic neuron in the spinal cord of the axolotl salamander. | two distinct groups of catecholaminergic neurons were observed by histofluorescence techniques in the spinal cord of the axolotl salamander, only one of which was detected in normal intact cords. these neurons were located in the ventral ependymal zone. when the spinal cord was transected, a second group of catecholaminergic neurons was observed in the lateral portions of the ventral gray matter of the spinal cord caudal to the transection site. these observations suggest that the amount of cate ... | 1986 | 3732481 |
| cellular contribution from dermis and cartilage to the regenerating limb blastema in axolotls. | using the triploid/diploid cell marker in the axolotl, ambystoma mexicanum, we have analyzed the extent to which cells derived from the dermis and the skeleton contribute to the regenerating limb blastema. we found that dermal cells contribute 43% of the blastemal cell population whereas cells derived from skeletal tissue contribute only 2%. when compared to the availability of cells at the plane of amputation, dermal cells overcontribute by greater than twofold whereas skeletal cells undercontr ... | 1986 | 3732605 |
| a scanning electron microscopy and histological study on the effects of the mutant eyeless (e/e) gene upon the hypothalamus in the mexican axolotl ambystoma mexicanum shaw. | a scanning electron microscopy, histological, and immunochemical investigation examined the effects of the mutant gene (e) upon hypothalamic development in the mexican axolotl. the adult eyeless mutant is sterile. previous studies indicated that this reproductive defect was due to the mutation's effect upon the hypothalamus. the present study demonstrated the pleiotropic effects of the eyeless gene upon development of the hypothalamus. scanning electron microscopy studies looked at the early ont ... | 1986 | 2426993 |
| the regeneration of double dorsal and double ventral limbs in the axolotl. | surgically made double dorsal and double ventral upper arms, comprising double extensor and double flexor muscles respectively, were amputated immediately following operation; both limb types regenerated. in terms of skeletal anatomy, a range of limb types was found. these included four-digit limbs of normal cartilage pattern, and hypomorphic limbs having from one to three digits. all of the double dorsal and the majority of the double ventral limbs were symmetrical in the dorsal-ventral axis. t ... | 1986 | 3760762 |
| effects of retinoic acid on regenerating normal and double half limbs of axolotls : histological studies. | retinoids induce proximodistal (pd) pattern duplication in zeugopodial (lower arm or leg) regenerates of normal limbs and pd pattern duplication plus anteroposterior (ap) pattern completion in double anterior half zeugopodial regenerates. in contrast, retinoids inhibit the regeneration of double posterior half zeugopodia (kim and stocum, 1986). here we describe the developmental histology of regenerating normal, double anterior half and double posterior half zeugopodia in axolotls after intraper ... | 1986 | 28306010 |
| induction of micronuclei in peripheral erythrocytes of axolotl larvae following in vivo exposure to mutagenic agents. | previous work from this laboratory demonstrated the presence of micronuclei in erythrocytes from larvae of the urodele amphibian pleurodeles waltl reared in water containing clastogenic substances. in order to investigate the generality of this finding, larvae from another urodele ambystoma mexicanum (axolotl) were reared in water containing one of the two following compounds: benzo[a]pyrene (bap) or ethylmethane sulphonate (ems). the level of micronucleated erythrocytes on blood smears was comp ... | 1986 | 3331662 |
| expression of dna ligase genes by ram spermatid nuclei and rna in amphibian eggs. | during animal development and gametogenesis two dna ligases are found and successively expressed. in this study the two dna ligases present in the axolotl egg and the two ligases present during ram sperm cell maturation were distinguished by biochemical and immunological methods. the expression of the genes for the heavy and light ram dna ligases has been studied using transplantation of spermatid and sperm nuclei in axolotl eggs. we found that ram dna ligases were expressed in axolotl egg cytop ... | 1986 | 28305254 |
| pattern discontinuity, polarity and directional intercalation in axolotl limbs. | axolotl limb stumps with dorsal-ventral confrontations between digits 2 and 3 but with a normal anterior-posterior pattern were created by grafting between contralateral limbs. graft and host differed in ploidy to permit a determination of the origin of cells in the regenerated limb. after regeneration, limbs were analysed for skeletal and muscle patterns and for the distribution of marked cells in the regenerate. regenerated limbs showed varying degrees of abnormality in their dorsal-ventral or ... | 1986 | 3734687 |
| the pigmentary system of developing axolotls. iii. an analysis of the albino phenotype. | the albino mutant in the mexican axolotl (ambystoma mexicanum) is analysed with respect to the differentiation of pigment cells. pigment cells were observed with the transmission electron microscope in order to determine any unusual structural characteristics and to determine what happens to each of the cell types as development proceeds. chemical analyses of pteridine pigments were also carried out, and the pattern of pteridines in albino animals was found to be more complex than, and quantitat ... | 1986 | 3723064 |
| the precision of pathway selection by developing peripheral axons in the axolotl. | at the time of hindlimb development in the axolotl there is a well-established but still developing trunk innervation. the trunk innervation is primarily composed of the segmental nerves, each of which consists of a dorsal and a ventral ramus and its branches. at a few segmental levels in the region of the hindlimb a large number of additional axons arise to innervate the limb. to reach the limb, they must grow via the ventral rather than the dorsal rami. the precision with which this pathway is ... | 1986 | 3711780 |
| urodele egg jelly and fertilization. | fertilization of urodele amphibians is physiologically polyspermic. these amphibians lack sperm entry blocking mechanisms at the egg surface, such as a cortical reaction or a membrane depolarization. although, egg jelly is necessary for sperm capacitation, a late block to sperm entry does occur about 30 min after fertilization at a precise interface between jelly layers. the jelly is secreted by oviductal cells. in order to investigate its role in fertilization, we studied some biochemical prope ... | 1986 | 3825680 |
| quantitative analysis of lymphocyte migration from the thymus to periphery in the mexican axolotl. | 1986 | 3817254 | |
| environmental control in pigment pattern formation of the axolotl larva. | 1986 | 3749176 | |
| investigating possible mechanisms of specific nerve regeneration in the axolotl. | 1986 | 3749170 | |
| regeneration from discontinuous circumferences in axolotl limbs. | 1986 | 3749160 | |
| involvement of the cytoskeleton in early gray crescent formation in axolotl oocyte: relationships with germinal vesicle breakdown. | 1986 | 3749155 | |
| biochemical and ultrastructural studies on vitamin a induced proximalization of limb regeneration in axolotl. | 1986 | 3749115 | |
| [structural characteristics and innervation of chromaffin tissue in the adrenal gland of the axolotl]. | each adrenal gland of the axolotl consists of a strip lying all along the medio-lateral edge on the ventral surface of the kidney. the gland is composed of interrenal cells (ic) and chromaffin cells (cc). the ic contained a great number of pleomorphic lipid droplets, smooth endoplasmic reticulum and elongated mitochondria with tubulo-vesicular cristae. two types of cc, always disposed in clusters and exhibiting long cytoplasmic processes were described according to the electron density, size and ... | 1986 | 3094843 |
| glucagon and insulin regulate in vitro hepatic glycogenolysis in the axolotl ambystoma mexicanum via changes in tissue cyclic amp concentration. | glucagon increases the rate of glycogenolysis in in vitro cultures of hepatic tissue from the axolotl ambystoma mexicanum. the hormone causes an increase in the concentration of cyclic amp in the tissue which is followed by activation of glycogen phosphorylase and subsequent breakdown of glycogen and release of glucose from the tissue. insulin counteracts the glycogenolytic effect of glucagon by inhibiting the increase in tissue cyclic amp concentration brought about by glucagon. this inhibitory ... | 1986 | 2416634 |
| increase of substance p-like immunoreactivity in the peripheral nerve of the axolotl after injury. | that substance p may be a neurotrophic factor in urodele limb regeneration was investigated in the axolotl (ambystoma mexicanum). two weeks after section of the peripheral nerves to the forelimb, there was a marked increase in substance p-like immunoreactivity (ir) content of the nerves proximal to the lesion. a smaller increase occurred as early as 3 days after section of nerves innervating a regrowing limb bud (blastema), and substance p-ir fibres were observed by immunocytochemistry to innerv ... | 1987 | 2447537 |
| anatomy of axolotl flank integument during limb bud development with special reference to a transcutaneous current predicting limb formation. | we have compared the anatomy of immature axolotl integument from limb-forming regions with adjacent non-limb-forming regions of the flank, concentrating on the earliest stages of limb bud development. we have extended these observations to include prominent buds just prior to their differentiation. at the ultrastructural level, we note striking differences between these two regions of skin, including a complete loss of hemidesmosomes and tonofilaments in the basal cells of the epidermis; a marke ... | 1987 | 3430119 |
| fine structure of taste buds in the tongue, palatal mucosa and gill arch of the axolotl, ambystoma mexicanum. | 1987 | 3431793 | |
| use of retinoids to analyze the cellular basis of positional memory in regenerating amphibian limbs. | cells of the amphibian limb regeneration blastema inherit memories of their level of origin (positional memory) along the limb axes. these memories serve as boundaries of what is to be regenerated, thus preventing regeneration of any but the missing structures. because of its importance in determining the boundaries of regenerate pattern, it is essential to understand the cellular and molecular basis of positional memory. one approach to this problem is to look for position-related differences i ... | 1987 | 3325080 |
| hormone action in newt limb regeneration: insulin and endorphins. | although several hormones have been linked to newt limb regeneration, a cohesive hypothesis as to how these hormones control the process is yet to emerge. a critical review of the traditional approaches and a reevaluation of currently operative assumptions and interpretations of results precede the data on insulin and beta-endorphin. results from in vivo and in vitro experiments on insulin are summarized, showing that insulin not only promotes various cellular events but also is essential for th ... | 1987 | 2963650 |
| involvement of the cytoskeleton in early grey crescent formation in axolotl oocytes. | maturing axolotl oocytes which are treated with protein synthesis inhibitors or which are heat-shocked can be induced to reorganize their cytoplasm and to form an early grey crescent. the maturing axolotl oocyte has been used as a model system to study the role of the cytoskeleton in dorsoventral polarization as visualized by grey crescent formation. results presented here provide evidence for the involvement of microtubules in the formation of the early grey crescent. whereas inhibitors of micr ... | 1987 | 28305553 |
| selective reinnervation of transplanted muscles by their original motoneurons in the axolotl. | the motoneurons innervating 3 hindlimb extensor muscles, anterior and posterior iliotibialis and iliofibularis, were studied separately by retrograde labeling with hrp. the motor pools for these 3 muscles overlapped to such an extent that individual motoneurons between ventral roots 16 and 17 could not be assigned unambiguously to one pool or another. thus, conventional retrograde labeling could not identify particular axolotl motoneurons. instead, a double retrograde-labeling technique was empl ... | 1987 | 3598652 |
| neurotransmitter-induced currents in retinal bipolar cells of the axolotl, ambystoma mexicanum. | 1. whole-cell patch clamping was used to study the membrane properties of isolated bipolar cells and the currents evoked in them by putative retinal neurotransmitters. 2. isolated bipolar cells show an approximately ohmic response to voltage steps over most of the physiological response range, with an average input resistance of 1.3 g omega and resting potential of -35 mv. these values are underestimates because of the shunting effect of the seal between the patch electrode and the cell membrane ... | 1987 | 2443677 |
| detection of mutagenicity in drinking water using a micronucleus test in newt larvae (pleurodeles waltl). | we have previously described a micronucleus test using erythrocytes from larvae of the urodele amphibians pleurodeles waltl (pleurodele) and ambystoma mexicanum (axolotl). the test is based on a comparison of the levels of micronucleated erythrocytes in blood smears from larvae reared in water containing a clastogen, with the levels from larvae reared in purified water. using larvae from the pleurodele, we have employed this test to evaluate mutagenic activity in drinking water. groups of larvae ... | 1987 | 3325745 |
| the effects of retinoic acid on mitosis during tail and limb regeneration in the axolotl larva, ambystoma mexicanum. | regenerating tails and limbs of axolotl larvae (a. mexicanum) were studied for overall growth and for mitosis after the animals received intraperitoneal injections of all-trans retinoic acid. both processes were depressed to approximately the same extent (60-70%). some mitosis always survived, even when the treatment was in effect during the entire history of the regenerate. the treatment duration was a major variable in the severity of the effect, whereas the post-amputation age of the regenera ... | 1987 | 28305840 |
| the surfactant system of the lung in the mexican axolotl ambystoma mexicanum. | the broncho-alveolar space of axolotl contains numerous osmiophilic structures, which have been classified morphologically into 3 types of inclusions. type i inclusions exhibited lattices of square to rectangular grid patterns with membranous elements 6 nm thick. this lattice was crossed by a 2 nm dense line. type ii inclusions were composed of 7 nm dark lines and 15.5 nm light lines in an alternating repeating pattern. furthermore, the light lines showed an intrapenoid line of 2 nm. type iii in ... | 1987 | 3581181 |
| dorsal root ganglia grafts stimulate regeneration of denervated urodele forelimbs: timing of graft implantation with respect to denervation. | amphibian forelimb regeneration is a nerve-dependent process; nerves presumably release one or more neurotrophic factors that stimulate blastema cell division. to date several candidate molecules/factors have been shown to stimulate macromolecular synthesis and/or mitosis but sustained cell cycle activity and blastema development have not been achieved. because dorsal root ganglia (drg) implants are capable of promoting regeneration of denervated adult newt limbs (kamrin & singer, 1959), we have ... | 1987 | 3652994 |
| induction of myofibrillogenesis in cardiac lethal mutant axolotl hearts rescued by rna derived from normal endoderm. | a strain of axolotl, ambystoma mexicanum, that carries the cardiac lethal or c gene presents an excellent model system in which to study inductive interactions during heart development. embryos homozygous for gene c contain hearts that fail to beat and do not form sarcomeric myofibrils even though muscle proteins are present. although they can survive for approximately three weeks, mutant embryos inevitably die due to lack of circulation. embryonic axolotl hearts can be maintained easily in orga ... | 1987 | 2443338 |
| the eyeless mutant mexican salamander (ambystoma mexicanum): evidence for an imbalanced anteroposterior morphogenetic system. | prospective anterolateral neural fold was grafted from normal axolotls into the posterior neural fold region (statocyst area) of eyeless mutant hosts. these unilateral anteroposterior grafts stimulated bilateral eye formation in the eyeless mutant at a rate of 79%. replacing the statocyst area of mutants with the statocyst area from normals stimulated bilateral eye formation in 49% of the cases. grafting of prospective anterolateral neural fold between normals and mutants or excising the statocy ... | 1987 | 3559793 |
| effects of exogenous guanosine on chromatophore differentiation in the axolotl. | guanosine is shown to dramatically alter the pigment phenotype of axolotls by suppressing melanization and enhancing the biosynthesis and deposition of purine-derived pigments. phenotypic changes caused by guanosine are manifested by altered chromatophore differentiation patterns such that few black pigment cells (melanophores) differentiate (and those that do are punctate and necrotic in appearance), whereas the development of yellow (xanthophore) and reflecting (iridophore) pigment cells is en ... | 1987 | 3507661 |
| is gaba an afferent transmitter in the vestibular system? | this study was undertaken to determine the possible role of gaba as an afferent transmitter in the vestibular system of the axolotl. we studied the effects of gaba, muscimol, bicuculline and picrotoxin on the spontaneous spike discharge of the afferent fibers of the sacculi lagena and anterior semicircular canal. it was found that gaba and muscimol produce a very weak excitatory effect which does not mimic either the temporal course or the amplitude of the response of vestibular afferents to phy ... | 1987 | 3497911 |
| the role of cartilage and fibronectin during respecification of pattern induced in the regenerating amphibian limb by retinoic acid. | when retinoic acid (ra) is applied to the regenerating limb the positional information of blastemal cells is respecified and extra limb segments develop. we are trying to elucidate the molecular basis of the action of ra and report here experiments focused on the role that fibronectin (fn) might play in the process. the fn distribution in stump tissues, regeneration blastemas and ra-treated blastemas was investigated by immunocytochemistry. two effects of ra were observed. firstly, excessive ded ... | 1987 | 3449397 |
| differentiation of cartilage from cranial neural crest in the axolotl (ambystoma mexicanum). | explants of cranial neural crest from neurula-stage ambystoma mexicanum embryos form cartilage nodules in 10-14 days, when cultured with pharyngeal endoderm. the time course of formation of the nodules, and their appearance, correspond closely to that observed for visceral cartilage in vivo. endoderm from any area of the sheet surrounding the pharyngeal cavity can induce cartilage formation, but endoderm from regions posterior to the pharyngeal cavity cannot. no other tissues are required for in ... | 1987 | 3428510 |
| changes in brain gangliosides of the neotene and metamorphic (thyroxine-induced) newt axolotl (ambystoma mexicanum). | qualitative and quantitative changes in the concentration of proteins, sialoglycoproteins and gangliosides and in the composition of gangliosides in the brains of the neotene and the thyroxine-induced metamorphic newt axolotl (ambystoma mexicanum) were investigated. during metamorphosis two polar gangliosides (gt1b and gq1b) decreased by about 5% each. on the contrary gd1a increased to 10%. another developmental trend was a slight increase of two other disialogangliosides (gd1b, gd2). additional ... | 1987 | 3428191 |
| bipolar cell membrane currents and signal processing in the axolotl retina. | 1987 | 2446219 | |
| basal lamina is not a barrier to neural crest cell emigration: documentation by tem and by immunofluorescent and immunogold labelling. | one of the factors proposed to control initiation of migration of neural crest (nc) cells is disruption of the basal lamina (bl) that is presumed to exist over the dorsal portion of the neural tube. previously, we discovered that, in the mouse embryo, a continuous bl is not deposited over the dorsal portion of the neural tube until emigration of the nc cells is terminated. here, we show that the pattern of bl deposition in chick embryos is similar, but not identical, to that in the mouse. in par ... | 1987 | 3332260 |
| immunocytochemical localization and spatial relation to the adenohypophysis of a somatostatin-like and a corticotropin-releasing factor-like peptide in the brain of four amphibian species. | the distribution of somatostatin (srif) - and corticotropin-releasing factor (crf)-like - immunoreactive material was studied in the brain of four amphibian species (ambystoma mexicanum, pleurodeles waltlii, xenopus laevis, rana ridibunda) by use of immunocytochemistry. a wide network of srif-immunoreactive fibers and numerous perikarya were observed in all amphibians examined, with a dense accumulation of nerve endings in the external layer of the median eminence (elme). in the representatives ... | 1987 | 2880668 |