Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| expression of integrins during axolotl limb regeneration. | limb regeneration in urodeles is achieved through the dedifferentiation of tissues at the amputation plane and through the production of the blastema. this tissue breakdown is possible by extensive alterations in molecules of the extracellular matrix. in this respect we describe the regulation of several integrins during such events. it was found that alpha 1 and beta 1 integrins were down-regulated as blastema formation proceeded. in contrast, the expression of alpha 3, alpha 6 and alpha v inte ... | 1997 | 9079030 |
| improved preservation of the subepidermal extracellular matrix in axolotl embryos using electron microscopical techniques based on cryoimmobilization. | the purpose of this metholdological survey was to find optimal methods for the fixation and demonstration of glycosaminoglycans, mainly hyaluronan, and proteoglycans, in subepidermal extracellular matrix (ecm) regions of axolotl embryos. we compared living ecm in the laser-scanning microscope (lsm) with chemically fixed or cryoimmobilized extracellular matrix in the transmission (tem) and scanning electron microscope (sem). the gel-like structure of living extracellular matrix in the lsm undoubt ... | 1997 | 9087914 |
| synaptic body movements in the sensory cells of lateral line organs in the urodele amphibian ambystoma mexicanum. | examination of the neuromasts in the tail of the living juvenile axolotl ambystoma mexicanum with interference contrast (nomarski) microscopy shows that their cellular structures can be identified in considerable detail. microscopy was performed with a 40 x water immersion objective or with a 100 x objective in a tail insertion chamber. thus the sensory hair bundles can be seen and their orientation can be determined. large spheres in the basal part of the sensory cells were predicted to be syna ... | 1997 | 9119761 |
| insights into pigmentary phenomena provided by grafting and chimera formation in the axolotl. | the expression of pigmentation patterns in axolotl pigmentary mutants was observed following three types of experimental manipulations including chimera formation, reciprocal neural crest grafts, of gonadal primordia. three pigmentary genes were utilized including the wild type (d), white (d), and albino (a). in chimeras between white and albino embryos, melanoblasts from the white half crossed the graft interface to differentiate in albino skin. neural crest grafts from white embryos to albinos ... | 1996 | 9125751 |
| expression pattern of an axolotl floor plate-specific fork head gene reflects early developmental differences between frogs and salamanders. | gastrulation is one of the most important stages of animal development and, as such, tends to be remarkably conserved. therefore it is interesting to see that the two amphibian species, xenopus laevis (frog) and ambystoma mexicanum (axolotl), are different in the arrangement of cell types just before and during gastrulation. in xenopus, the cells that will form dorsal mesoderm are located deep in the dorsal marginal zone, while in the axolotl, these are on the surface of the embryo. in this stud ... | 1997 | 9144925 |
| thyroid hormone receptor genes of neotenic amphibians. | since thyroid hormones play a pivotal role in amphibian metamorphosis we used pcr to amplify dna fragments corresponding to a portion of the ligand-binding domain of the thyroid hormone receptor (tr) genes in several neotenic amphibians: the obligatory neotenic members of the family proteidea the mudpuppy necturus maculosus and proteus anguinus as well as two members of the facultative neotenic ambystoma genus: the axolotl ambystoma mexicanum and the tiger salamander ambystoma tigrinum. in addit ... | 1997 | 9169551 |
| glial fibrillary acidic protein and vimentin in radial glia of ambystoma mexicanum and triturus carnifex: an immunocytochemical study. | the molecular characterization of glial lineage cells in two urodele species, ambystoma mexicanum and triturus carnifex, has been investigated immunocytochemically with antibodies directed against intermediate filament proteins, glial fibrillary acidic protein (gfap) and vimentin. ambystoma astroglia shows clear gfap-immunopositivity and vimentin-immunonegativity. the condition in triturus is quite the opposite, showing only a strong vimentin immuno-reaction. in these urodele brain the astroglia ... | 1997 | 9176731 |
| effects of urea on m4-lactate dehydrogenase from elasmobranchs and urea-accumulating australian desert frogs. | we measured the effect of urea on m4-lactate dehydrogenase (m4-ldh) from elasmobranchs and australian desert frogs (urea accumulators) and from two animals that do not accumulate urea, the axolotl and the rabbit. an analysis of the effect of urea on the kd(nadh), v, v/k(m(prr)) and v/k(m(nadh)) shows that in all cases the major effect of urea was on the binding of pyruvate, which fits with data in the literature that show that urea acts as a competitive inhibitor of ldh. the characteristics of t ... | 1997 | 9180022 |
| melatonin levels in the gastrointestinal tissues of fish, amphibians, and a reptile. | melatonin was detected by radioimmunoassay in the gastrointestinal tract (git) of several species of fish (sturgeon, rainbow trout, carp), amphibians (axolotl, leopard frog, bullfrog), and one reptile (red-sided garter snake), which were sacrificed during the daytime. the highest levels of melatonin were detected in the snake [means = 1018 pg/g stomach, 328 pg/g proximal gut (pg), 511 distal gut (dg)] and carp (means = 102 pg/g stomach, 146 pg/g pg and 141 pg/g dg). lowest levels were found in t ... | 1997 | 9204376 |
| structure and diversity of the heavy chain vdj junctions in the developing mexican axolotl. | the immune capacity of young and adult axolotls (ambystoma mexicanum) was evaluated by examining the combinatorial and junctional diversity of the vh chain. a large number of vdj rearrangements isolated from 2.5-, 3.5-, 10-, and 24-month-old animals were sequenced. six jh segments were identified with the canonical structure of all known vertebrate jhs, including the conserved trp103-gly104-x-gly106 motif. four core dh-like sequences were used by most (80%) of the vdj junctions. these g-rich seq ... | 1997 | 9271630 |
| abbreviated junctional sequences impoverish antibody diversity in urodele amphibians. | of the six complementarity-determining regions (cdr) forming the structure of the ab combining site, cdr3 of heavy chain is the most variable in length and sequence. diversity of this loop is determined by the number of gene segments involved, extent of addition to or deletion from the joining genes, and imprecision of the site of recombination. in neonatal mice and xenopus tadpoles, the last two factors occur less frequently than in adults, which in tadpoles result in low affinity ab responses ... | 1997 | 9317138 |
| kinematics and efficiency of steady swimming in adult axolotls (ambystoma mexicanum) | the kinematics of steady swimming at a wide range of velocities was analysed using high-speed video recordings (500 frames s-1) of eight individuals of ambystoma mexicanum swimming through a tunnel containing stationary water. animals in the observed size range (0.135­0.238 m total body length) prefer to swim at similar absolute speeds, irrespective of their body size. the swimming mechanism is of the anguilliform type. the measured kinematic variables ­ the speed, length, frequency and ... | 1997 | 9319776 |
| reduced epidermal expression of a pg-m/versican-like proteoglycan in embryos of the white mutant axolotl. | axolotl embryos have previously been used to study neural crest cell migration. in embryos of the normal wild type, neural crest cells migrate subepidermally to form pigment cells. in the trunk of the white mutant embryo, these cells are unable to migrate, possibly due to an inherited delay in the maturation of the local extracellular matrix. the present investigation reveals a reduced incorporation of [35s]sulfate into pg-m/versican-like proteoglycans synthesized in epidermal explants from the ... | 1997 | 9344585 |
| a primary cell culture model for defective cardiac myofibrillogenesis in mexican axolotl embryos. | 1997 | 9358282 | |
| taste disks are induced in the lingual epithelium of salamanders during metamorphosis. | morphological changes of oral cavity during metamorphosis with special reference to the taste organ were examined in ezo salamanders (hynobius retardatus) and axolotis (ambystoma mexicanum), and compared with those in bullfrogs (rana catesbeiana). the non-distensible tongue of salamanders changed the structure progressively during metamorphosis: a small area of the rostrum protruded and developed caudally with recession of the flat area of the tongue. the protrusion that developed on the tongue ... | 1997 | 9363353 |
| the role of thyroid hormone in zebrafish and axolotl development. | exogenous thyroid hormone (th) induces premature differentiation of the zebrafish pectoral fins, which are analogous to the forelimbs of tetrapods. it accelerates the growth of the pelvic fins but not precociously. goitrogens, which are chemical inhibitors of th synthesis by the thyroid gland, inhibit the transition from larva to juvenile fish including the formation of scales, and pigment pattern; they stunt the growth of both pectoral and pelvic paired fins. inhibition by goitrogens is rescued ... | 1997 | 9371791 |
| hormone-induced rise in cytosolic ca2+ in axolotl hepatocytes: properties of the ca2+ influx channel. | calcium entry in nonexcitable cells occurs through ca(2+)-selective channels activated secondarily to store depletion and/or through receptor- or second messenger-operated channels. in amphibian liver, hormones that stimulate the production of adenosine 3',5'-cyclic monophosphate (camp) also regulate the opening of an ion gate in the plasma membrane, which allows a noncapacitative inflow of ca2+. to characterize this ca2+ channel, we studied the effects of inhibitors of voltage-dependent ca2+ ch ... | 1997 | 9374637 |
| adaptive evolution via a major gene effect: paedomorphosis in the mexican axolotl. | although adaptive evolution is thought to depend primarily on mutations of small effect, major gene effects may underlie many of the important differences observed among species in nature. the mexican axolotl (ambystoma mexicanum) has a derived mode of development that is characterized by metamorphic failure (paedomorphosis), an adaptation for an entirely aquatic life cycle. by using an interspecific crossing design and genetic linkage analysis, a major quantitative trait locus for expression of ... | 1997 | 9391174 |
| abnormal limb regeneration in the short-toes mutant of the axolotl, ambystoma mexicanum: studies of age, level of amputation, and extracellular matrix. | limb regeneration in the short-toes axolotl is impaired. our goal was to characterize the regeneration process in this mutant by histological and immunocytochemical methods. previous research indicates that age and a defective basement membrane may be instrumental factors in short-toes axolotl regeneration (del rio-tsonis et al. [1992] proc. natl. acad. sci. u.s.a., 89:5502-5506). the present results show that limb regeneration can occur even in older (1-2-year-old) short-toes axolotls. the proc ... | 1997 | 9399429 |
| cloning of a complementary dna encoding an ambystoma mexicanum metallothionein, ammt, and expression of the gene during early development. | we have used a polymerase chain reaction strategy to isolate a metallothionein (mt) cdna from the amphibian ambystoma mexicanum (axolotl). this cdna is 875-bp long and encodes a 60 amino acid protein, ammt, typical for family 1 mts. it contains 20 cysteine (cys) residues that can be aligned with those of other vertebrate mts. the overall structure of the protein is unique among vertebrates in having only two amino acid residues before the first cys at the amino-terminal end. northern analyses sh ... | 1998 | 9468225 |
| transferrin is necessary and sufficient for the neural effect on growth in amphibian limb regeneration blastemas. | cell proliferation during the early phase of growth in regenerating amphibian limbs requires a permissive influence of nerves. based on analyses of proliferative activity in denervated blastemas, it was proposed that nerves provide factors important for cells to complete the proliferative cycle rather than for mitogenesis itself. one such factor, the iron-transport protein transferrin (tf), is abundant in regenerating peripheral nerves where it is axonally transported and released at growth cone ... | 1997 | 9493827 |
| molecular cloning from neurulating ambystoma mexicanum embryos of the cdna encoding an orphan nuclear receptor (ador1) closely related to tr2-11. | we have isolated a cdna encoding a novel orphan nuclear receptor, ador1, closely related to testicular receptor-2 (tr2) orphan receptor family members, from neurulating ambystoma mexicanum embryos. the cdna sequence predicts a protein primary sequence of 416 amino acids with a calculated molecular weight of 45.8 kda. while the dna-binding domains of ador1 and htr2-11 share 96% identity, considerable divergence is observed at both extremities of the peptides. at the n-terminus, ador1 is 66% ident ... | 1997 | 9503600 |
| molecular biology of heart development in the mexican axolotl, ambystoma mexicanum. | 1997 | 9505339 | |
| wide tissue distribution of axolotl class ii molecules occurs independently of thyroxin. | unlike most salamanders, the mexican axolotl (ambystoma mexicanum) fails to produce enough thyroxin to undergo anatomical metamorphosis, although a "cryptic metamorphosis" involving a change from fetal to adult hemoglobins has been described. to understand to what extent the development of the axolotl hemopoietic system is linked to anatomical metamorphosis, we examined the appearance and thyroxin dependence of class ii molecules on thymus, blood, and spleen cells, using both flow cytometry and ... | 1998 | 9510551 |
| immunolocalization of aromatic l-amino acid decarboxylase, tyrosine hydroxylase, dopamine, and serotonin in the forebrain of ambystoma mexicanum. | to improve basic knowledge about the neurochemical organization of the urodele brain, and to study discrepancies in the localization of monoaminergic markers, we immunohistochemically charted the distribution of four such markers (tyrosine hydroxylase, aromatic l-amino acid decarboxylase, dopamine, and serotonin) in the axolotl (ambystoma mexicanum) forebrain. catecholaminergic and serotoninergic systems were found in similar locations to those seen in other urodela. as seen in other vertebrates ... | 1998 | 9518271 |
| cellular plasticity among axolotl neural crest-derived pigment cell lineages. | many of the factors and mechanisms guiding the migration/differentiation of neural crest cells that give rise to a number of distinguishable cell types, including all dermal and epidermal pigment cells, remain unknown. the axolotl possesses three pigment cell types that differentiate according to specific developmentally programmed sequences and contribute to pigment pattern in the adult. a single lineage of the crest that becomes restricted to one of three pigment cell types gives us the opport ... | 1998 | 9523334 |
| regulation of homeobox-containing genes during lens regeneration. | in this study, the expression of homeobox-containing genes was evaluated after lentectomy in the newt, which is competent for lens regeneration, and in the axolotl which is not. such a comparison was designed to offer insights about possible regulation due to regenerative abilities. six homeobox-containing genes were examined: nvhox a4, nvhox b1, nvhox 7, nvhox x, nvmsx-1 and xbr1. for all genes examined, it was found that soon after lentectomy in the newt there was a general down-regulation in ... | 1998 | 9533863 |
| structure, diversity, and repertoire of vh families in the mexican axolotl. | the mexican axolotl v(h) segments associated with the igh c mu and c nu isotypes were isolated from anchored pcr libraries prepared from spleen cell cdna. the eight new v(h) segments found bring the number of v(h) families in the axolotl to 11. each v(h) had the canonical structural features of vertebrate v(h) segments, including residues important for the correct folding of the ig domain. the distribution of ser agc/t (agy) and tcn codons in axolotl v(h) genes was biased toward agy in complemen ... | 1998 | 9570539 |
| the heart of metamorphosing mexican axolotl but not that of the cardiac mutant is associated with the upregulation of hox a5. | the mexican axolotl (ambystoma mexicanum) is a facultative neotene which rarely undergoes metamorphosis in the wild. we now report for the first time a dramatic increase in the expression of hoxa5 in axolotl hearts as determined by rt-pcr and in situ hybridization analyses during spontaneous metamorphosis. the mexican axolotl has a naturally occurring mutation called gene c which allows hearts in homozygous (c/c) embryos to form but never to beat. rt-pcr analysis has not shown any significant di ... | 1998 | 9588186 |
| axolotl (ambystoma mexicanum) lymphocytes produce and are growth-inhibited by transforming growth factor-beta. | recombinant (r)tgf-beta 5, an isoform of tgf-beta thus far identified only in the frog, xenopus' laevis, inhibited phytohemagglutinin (pha)-induced mitogenesis of salamander (axolotl) splenocytes and thymocytes, and t cell growth factor-induced proliferation of splenic lymphoblasts. this inhibition could be reversed by incubating (r)tgf-beta 5 with an anti-tgf-beta 5 antibody, but not with an antibody directed against tgf-beta 2, another xenopus-produced tgf-beta isoform. acid-treated supernatan ... | 2007 | 9617586 |
| [study of amphibian brain asymmetry during normal embryonic and larval development]. | amphibian embryos (triturus vulgaris, pleurodeles waltl, hynobius keyserlingii, ambystoma mexicanum, rana temporaria, bufo bufo, and xenopus laevis) were investigated. we ascertained the morphological right-side asymmetry of the brain, which appears at the neurula stage and is preserved during the postembryonic (larval) development. in t. vulgaris, p. waltl, h. keyserlingii, and x. laevis, we observed right-side asymmetry of peripheral analyzers, such as the retina, ganglia of nerve viii, and ol ... | 1998 | 9644914 |
| cloning and sequencing of the cdna for an rna-binding protein from the mexican axolotl: binding affinity of the in vitro synthesized protein. | a full length cdna for an rna-binding protein (axolotl rbp) with consensus sequence (rnp-cs) from the mexican axolotl, ambystoma mexicanum, has been cloned from a subtraction library. in vitro translation with synthetic mrna and subsequent hybrid-arrested translation with a specific antisense oligonucleotide confirms that the axolotl rbp cdna encodes an approx. 16 kda polypeptide. computer-assisted analyses revealed amino acid similarities of 58-60% to various rna-binding proteins and a 90 amino ... | 1998 | 9655917 |
| post-transcriptional control of c-myc rna during early development analyzed in vivo with a xenopus-axolotl heterologous system. | we have set up a heterologous in vivo system to study gene regulation at the post-transcriptional level during early development. this system uses two amphibian species, xenopus laevis and ambystoma mexicanum (axolotl), the development of which is three to four times slower than that of x. laevis. the stability of three different synthetic x. laevis c-myc transcripts was followed after injection into fertilized axolotl eggs. one transcript is 2.2 kilobases (kb) long (full-length). the second is ... | 1998 | 9674116 |
| effect of calcium on development of amiloride-blockable na+ transport in axolotl in vitro. | the axolotl, ambystoma mexicanum, which has no specific calcium-containing sieve layer in the dermis, provides useful material for the study of the effect of ca2+ on the development of amiloride-blockable active na+ transport across the skin of amphibians. we raised axolotls in thyroid hormone or aldosterone or cultured the skin with corticoid plus one of several ca2+ concentrations and found that 1) although the short-circuit current (scc) was increased by both aldosterone and 3,3',5-triiodo-l- ... | 1998 | 9688962 |
| expression of hoxd genes in developing and regenerating axolotl limbs. | hox genes play a critical role in the development of the vertebrate axis and limbs, and previous studies have implicated them in the specification of positional identity, the control of growth, and the timing of differentiation. axolotl limbs offer an opportunity to distinguish these alternatives because the sequence of skeletal differentiation is reversed along the anterior-posterior axis relative to that of other tetrapods. we report that during early limb development, expression patterns of h ... | 1998 | 9705229 |
| anterior/posterior influences on neural crest-derived pigment cell differentiation. | the neural crest of vertebrate embryos has been used to elucidate steps involved in early embryonic cellular processes such as differentiation and migration. neural crest cells form a ridge along the dorsal midline and subsequently they migrate throughout the embryo and differentiate into a wide variety of cell types. intrinsic factors and environmental cues distributed along the neural tube, along the migratory pathways, and/or at the location of arrest influence the fate of neural crest cells. ... | 1998 | 9711533 |
| cloning, sequencing and expression of a novel homeobox gene axnox-1 from the mexican axolotl. | we have cloned and sequenced a cdna containing a homeobox gene, axnox-1, from a stage 18 axolotl embryonic cdna library which shows only moderate levels of similarity to other known homeobox genes. the nucleotide sequence of the cdna has an open reading frame for 335 amino acids and besides the homeodomain, there is an acidic domain and a proline-rich domain present in the protein. the transcripts for this gene are detectable at stage 4 of embryonic development and, hence, there is a good possib ... | 1998 | 9714797 |
| three-dimensional reconstruction of live embryos using robotic macroscope images. | to determine the three-dimensional (3-d) shape of a live embryo is a technically challenging task. we show that reconstructions of live embryos can be done by collecting images from different viewing angles using a robotic macroscope, establishing point correspondences between these views by block matching, and using a new 3-d reconstruction algorithm that accommodates camera positioning errors. the algorithm assumes that the images are orthographic projections of the object and that the camera ... | 1998 | 9735567 |
| evidence for introduction of a variable g1 phase at the midblastula transition during early development in axolotl. | after fertilization in axolotl, the synchronous cell cleavages are triphasic (s, g2 and m phases). midblastula transition (mbt) begins at the ninth cleavage and is the consequence of lengthening of cell cycles. by spectrofluorometry and incorporation of 3h thymidine into the nuclear dna followed by autoradiography on individual cells, the time at which a g1 phase appears during early development was investigated. the present results show that the g1 phase was introduced for the first time at mbt ... | 1998 | 9783475 |
| on the conservation of calcium wave speeds. | most long distance calcium signals are believed to take the form of actively propagated calcium waves. in 1991, when this proposal was first advanced, all such waves were thought to belong to one class, for which fertilization waves were the prototype. moreover, the speeds of such waves were found to be conserved at about 10 microns/s for primary fertilization waves and 30 microns/s for waves through fully active systems at 20 degrees c. in 1993, preliminary evidence for a second class of such w ... | 1998 | 9793683 |
| effects of peripheral nerve implants on the regeneration of partially and fully innervated urodele forelimbs. | this study addresses the cellular mechanism of the nerve requirement for regeneration of the urodele forelimb. others have suggested that only the schwann cell lineage of the blastema requires nerves for regeneration and that upon limb denervation, schwann cells arrest in the cell cycle and produce a factor that inhibits the cycling of the remaining blastema cells. our objective was to test this schwann cell inhibitor model. first, pieces of peripheral nerve were implanted into partially denerva ... | 2006 | 9824557 |
| interspecies variations in oral epithelial cytokeratin expression. | the aim of this study was to determine the degree to which the epidermis and oral epithelium of species other than man express cytokeratin (ck) intermediate filaments, which are markers of epithelial differentiation. fixed, wax-embedded samples of skin, buccal mucosa and gingiva from rhesus monkey, marmoset, cow, sheep, pig, ferret, hamster, axolotl and trout were tested for ck expression using a panel of antihuman ck antibodies and an immunoperoxidase procedure. human skin and oral mucosa were ... | 1998 | 9827634 |
| comparative analysis of gnrh neuronal systems in the amphibian brain. | we have investigated the gnrh-ir neuronal systems in the brain of the oviparous urodele, triturus vulgaris, ovoviviparous urodele, salamandra salamandra, and viviparous caecilian, typhlonectes compressicauda, and have reexamined xenopus laevis, ambystoma mexicanum, and rana esculenta. results showed that mgnrh neuronal system was diffused along the medioventral telencephalon and diencephalon with the numerical preponderance of gnrh cell bodies in the rostral mediobasal telencephalon in t. vulgar ... | 1998 | 9843639 |
| expression of msx genes in regenerating and developing limbs of axolotl. | msx genes, homeobox-containing genes, have been isolated as homologues of the drosophila msh gene and are thought to play important roles in the development of chick or mouse limb buds. we isolated two msx genes, msx1 and msx2, from regenerating blastemas of axolotl limbs and examined their expression patterns using northern blot and whole mount in situ hybridization during regeneration and development. northern blot analysis revealed that the expression level of both msx genes increased during ... | 1998 | 9846382 |
| expression of msx-2 during development, regeneration, and wound healing in axolotl limbs. | msx genes are transcription factors that are expressed during embryogenesis of developing appendages in regions of epithelial-mesenchymal interactions. various lines of evidence indicate that these genes function to maintain embryonic tissues in an undifferentiated, proliferative state. we have identified the axolotl homolog of msx-2, and investigated its expression during limb development, limb regeneration, and wound healing. as in limb buds of higher vertebrates, axolotl msx-2 is expressed in ... | 1998 | 9846383 |
| retinoic acid and thyroid hormone may function through similar and competitive pathways in regenerating axolotls. | the objective of this study was to determine whether thyroid hormone (th) would interfere with retinoic acid (ra), which proximalizes axolotl larvae regenerate limb pattern. ra and th are ligands for members of the steroid hormone thyroid hormone nuclear binding protein superfamily which form functional homodimers, but may also form stable heterodimers with the rxr protein and may recognize identical dna sequences. th alone does not affect limb pattern but induces metamorphosis in regenerating a ... | 1998 | 9846384 |
| ectopic expression of tropomyosin promotes myofibrillogenesis in mutant axolotl hearts. | expression of tropomyosin protein, an essential component of the thin filament, has been found to be drastically reduced in cardiac mutant hearts of the mexican axolotl (ambystoma mexicanum) with no formation of sarcomeric myofibrils. therefore, this naturally occurring cardiac mutation is an appropriate model to examine the effects of delivering tropomyosin protein or tropomyosin cdna into the deficient tissue. in this study, we describe the replacement of tropomyosin by using a cationic liposo ... | 1998 | 9853962 |
| expression of the third component of complement, c3, in regenerating limb blastema cells of urodeles. | in this study we have shown that complement component c3 is expressed in the regenerating tissue during urodele limb regeneration. c3 was expressed in the dedifferentiated regeneration blastema and in the redifferentiated limb tissues in the axolotl, amblystoma mexicanum, and in notophthalmus viridescens. this expression was verified by immunofluorescent staining using an ab against axolotl c3 and by in situ hybridization with an axolotl c3 cdna probe. in the early stages of regeneration c3 appe ... | 1998 | 9862713 |
| isolation, amino acid sequence determination and binding properties of two fatty-acid-binding proteins from axolotl (ambistoma mexicanum) liver. evolutionary relationship. | up until now, the primary structure of fatty-acid-binding proteins (fabps) from the livers of four mammalian (rat, human, cow and pig) and three nonmammalian (chicken, catfish and iguana) species has been determined. based on amino acid sequence comparisons, it has been suggested that mammalian and nonmammalian liver fabps may be paralogous proteins that originated by gene duplication, rather than as a consequence of mutations of the same gene. in this paper we report the isolation and amino aci ... | 1999 | 9914484 |
| structure of mhc class i and class ii cdnas and possible immunodeficiency linked to class ii expression in the mexican axolotl. | despite the fact that the axolotl (ambystoma spp. a urodele amphibian) displays a large t-cell repertoire and a reasonable b-cell repertoire, its humoral immune response is slow (60 days), non-anamnestic, with a unique igm class. the cytotoxic immune response is slow as well (21 days) with poor mixed lymphocyte reaction stimulation. therefore, this amphibian can be considered as immunodeficient. the reason for this subdued immune response could be an altered antigenic presentation by major histo ... | 1998 | 9914918 |
| the role of innervation in the development of taste buds: insights from studies of amphibian embryos. | amphibian embryos have long been model organisms for studies of development because of their hardiness and large size, as well as the ease with which they can be experimentally manipulated. these particular advantages have allowed us recently to test the role of innervation in the development of vertebrate taste buds using embryos of an aquatic salamander, the axolotl. the predominant model of taste bud genesis has been one of neural induction, in which ingrowing sensory neurites induce taste bu ... | 1998 | 9929586 |
| changes of the lingual epithelium in ambystoma mexicanum. | changes in the lingual epithelium during ontogenesis and after induced metamorphosis in ambystoma mexicanum are described as observed by light microscopy and scanning electron microscopy. the epithelium of the tongue is always multilayered in the larva as well as in the adult. it consists of a stratum germinativum with little differentiated basal cells and a stratum superficiale (superficial layer) with specialized superficial cells and goblet cells. usually, there are more than two layers becau ... | 1998 | 10099954 |
| the cardiac mutant mexican axolotl is a unique animal model for evaluation of cardiac myofibrillogenesis. | hearts from cardiac mutant mexican axolotl, ambystoma mexicanum, do not form organized myofibrils and fail to beat. though previous biochemical and immunohistochemical experiments showed a possible reduction of cardiac tropomyosin it was not clear that this caused the lack of organized myofibrils in mutant hearts. we used cationic liposomes to introduce both rabbit and chicken tropomyosin protein into whole hearts of embryonic axolotls in whole heart organ cultures. the mutant hearts had a strik ... | 1999 | 10222147 |
| cutaneous mastocytomas in the neotenic caudate amphibians ambystoma mexicanum (axolotl) and ambystoma tigrinum (tiger salamander). | spontaneous mastocytomas studied in 18 axolotls (ambystoma mexicanum) and six tiger salamanders (ambystoma tigrinum) were gray-white, uni- to multilobular cutaneous protrusions from 2 mm to 2 cm in diameter. tumors were moderately cellular unencapsulated masses that usually infiltrated the dermis and hypodermis with the destruction of intervening tissues. some tumors were invading superficial bundles of the underlying skeletal muscle. tumors consisted of mitotically active cells derived from a s ... | 1999 | 10235473 |
| genetic analysis of steel and the pg-m/versican-encoding gene axpg as candidates for the white (d) pigmentation mutant in the salamander ambystoma mexicanum. | vertebrate non-retinal pigment cells are derived from neural crest (nc) cells, and several mutations have been identified in the mexican axolotl ambystoma mexicanum (ambystomatidae) that affect the development of these cell lineages. in "white" (d) mutant axolotls, premigratory nc cells differentiate as pigment cells, yet fail to disperse, survive, or both, and this leads to a nearly complete absence of pigment cells in the skin. previous studies revealed that d affects pigment cell development ... | 1999 | 10370116 |
| neurohormonal peptides, serotonin, and nitric oxide synthase in the enteric nervous system and endocrine cells of the gastrointestinal tract of neotenic and thyroid hormone-treated axolotls (ambystoma mexicanum). | immunoreactivity against vasoactive intestinal polypeptide (vip), neurotensin (nt), substance p (sp), calcitonin gene-related peptide (cgrp), gastrin/cholecystokinin (gas/cck), somatostatin (som), serotonin (ser), and nitric oxide synthase (nos) was investigated in the gastrointestinal tract of the urodele ambystoma mexicanum, the axolotl, by the use of immunohistochemical techniques. the study also compares the distribution patterns and frequencies of the neurohormones, and nos in neotenic and ... | 1999 | 10398886 |
| natural and induced apoptosis during lymphocyte development in the axolotl. | lymphocytes apoptosis was characterized in a urodele amphibian, the axolotl, by morphology using electron microscopy and by flow cytometry after propidium iodide staining, as well as by biochemical criteria with the detection of dna ladders after glucocorticoid treatment. the morphological and biochemical features observed in treated axolotls are in accordance with the criteria of apoptosis found in different models of mammalian lymphocyte programmed cell death. the onset of natural apoptosis wa ... | 1999 | 10402211 |
| sonic hedgehog (shh) expression in developing and regenerating axolotl limbs. | sonic hedgehog (shh) expression is detectable in the posterior mesenchyme of many developing vertebrate limbs. we have isolated an rt-pcr fragment from the axolotl, ambystoma mexicanum, that has high identity to other vertebrate shh genes. we describe the localization of this transcript during development and regeneration and in response to tissue grafts and retinoic acid (ra) exposure in the axolotl. even though axolotl digits show a reversed polarity of differentiation (anterior [a] to posteri ... | 1999 | 10404648 |
| the cardiac neural crest in ambystoma mexicanum. | to establish whether a region of the cranial neural crest contributes cells to the developing heart of ambystoma mexicanum (axolotl), as it does in many other vertebrates, we constructed a fate map for the neural crest in late neurula stage (stage 19-20) embryos. the fluorescent vital dye, dil, was used as the lineage label. the various regions of the cranial neural folds were identified in relation to such landmarks as the developing forebrain, midbrain and hindbrain, and the appearance and ext ... | 1999 | 10410907 |
| lectin binding patterns in amphibian skin epithelium. | seven lectins (pna, dba, wga, uea-i, rca, sba, con a) were used to localize glycoconjugates in the skin of 10 species of amphibia, 7 anurans (bufo marinus, bufo bufo, rana ridibunda, rana pipiens, hyla arborea, pelobates syriacus and xenopus laevis) and 3 urodeles (salamandra salamandra, triturus vulgaris and ambystoma mexicanum). it was found that every lectin has a specific binding pattern in the skin of each species. no common pattern could be established, either among frogs or toads, nor for ... | 1999 | 10443294 |
| axolotl/newt. | 1999 | 10443382 | |
| the axolotl as an animal model for the comparison of 3-d ultrasound with plain film radiography. | we assessed the usefulness of an animal model, the axolotl (ambystoma mexicanum), in comparing 3-d ultrasound (3-d us) and plain film radiographs. hindlimbs were amputated from 5 animals, at either the zeugopodial or stylopodial level, and each regenerating limb was imaged 16 times with 3-d us and 14 times with plain film x ray over 315 days. us images were acquired with a siemens sonoline versa pro and a 10-mhz linear array transducer. for 3-d us images, the probe was translated in a motor-driv ... | 1999 | 10461726 |
| expression of axolotl rna-binding protein during development of the mexican axolotl. | amphibians occupy a central position in phylogeny between aquatic and terrestrial vertebrates and are widely used as model systems for studying vertebrate development. we have undertaken a comprehensive molecular approach to understand the early events related to embryonic development in the mexican axolotl, ambystoma mexicanum, which is an exquisite animal model for such explorations. axolotl rbp is a rna-binding protein which was isolated from the embryonic mexican axolotl by subtraction hybri ... | 1999 | 10470498 |
| expression of mmp-9 and related matrix metalloproteinase genes during axolotl limb regeneration. | one of the earliest events in limb regeneration is the extensive remodeling of the extracellular matrix (ecm). matrix metalloproteinases (mmps) are a family of matrix degrading enzymes that have been identified in both normal and disease states. using rt-pcr and cdna library screening, we have isolated sequences homologous to four different mmp genes. the spatial and temporal expression of one of these, mmp-9, has been analyzed during axolotl limb regeneration. northern blot analysis identifies ... | 1999 | 10474160 |
| loss of ectodermal competence for lateral line placode formation in the direct developing frog eleutherodactylus coqui. | in the direct-developing frog eleutherodactylus coqui neuromasts and ganglia of the lateral line system never develop. we show here that this absence of the lateral line system, which is evolutionarily derived in anurans, is due to very early changes in development. ectodermal thickenings, which are typical of lateral line placodes, and from which neuromasts and ganglion cells of the lateral line originate, never form in e. coqui, although other neurogenic placodes are present. moreover, althoug ... | 1999 | 10479453 |
| axolotl mhc architecture and polymorphism. | the mhc of the urodele amphibian ambystoma mexicanum consists of multiple polymorphic class i loci linked, so far as yet known, to a single class ii b locus. this architecture is very different from that of the anuran amphibian xenopus. the number of class i loci in the axolotl can vary from 6 to 21 according to the haplotypes as shown by cdna analysis and southern blot studies in families. these loci can be classified into seven sequence groups with features ranging from the class ia to the cla ... | 1999 | 10508264 |
| cloning of a cdna for xdor2, a novel tr2-related nuclear orphan receptor, expressed during neurulation in xenopus laevis embryos. | we isolated from neurulating xenopus laevis (x. laevis) embryos a cdna encoding a novel nuclear orphan receptor, developmental orphan receptor 2 (xdor2), closely related to ambystoma mexicanum dori (ador1) and to testicular receptor-2 (tr2) orphan receptor family members. the xdor2 cdna sequence which is truncated both at its 5' and 3' ends predicts a protein sequence of 542 amino acids. while the dna-binding domain of xdor2 shares 91%, and 92%, identity with those of ador1 and the tr2s, respect ... | 1998 | 10520740 |
| planar signalling is not sufficient to generate a specific anterior/posterior neural pattern in pseudoexogastrula explants from xenopus and triturus. | early observations on the morphology of total exogastrulae from urodeles (axolotl) had provided evidence for essential vertical signalling mechanisms in the process of neural induction. conversely, more recent studies with anurans (xenopus laevis) making use of molecular markers for neural-specific gene expression appear to support the idea of planar signalling as providing sufficient information for neural differentiation along the anterior-posterior axis. in an attempt to resolve this apparent ... | 2000 | 10585562 |
| the epithelium of the tongue of ambystoma mexicanum. ultrastructural and histochemical aspects. | the distribution pattern of taste buds and goblet cells and histochemical and ultrastructural aspects of the tongue epithelium of ambystoma mexicanum are here described. this study is also concerned with the developmental stages and origins of the epithelial cells. pavement cells and goblet cells of the stratum superficiale are replaced by basal cells of the stratum germinativum in larvae and neotenous adults. the pavement cells of the larvae are characterized by a marginal layer of mucin grana. ... | 1999 | 10609049 |
| structure and developmental expression of ikaros in the mexican axolotl. | the ikaros family of transcription factors plays an essential role in hematopoiesis. we report here the structure of cdna clones encoding two ikaros isoforms, ikl and ik2, in the mexican axolotl. the ik1 cdna sequence is very similar to that of the rainbow trout, chicken, and mammalian ik1 sequences. however, a 96 base pair region which encodes the first n-terminal zing finger (f1) is lacking from axolotl ik1, both in clones from a cdna library and clones isolated from direct polymerase chain re ... | 1999 | 10630298 |
| vaccinia as a tool for functional analysis in regenerating limbs: ectopic expression of shh. | axolotls, with their extensive abilities to regenerate as adults, provide a useful model in which to study the mechanisms of regeneration in a vertebrate, in hopes of understanding why other vertebrates cannot regenerate. although the expression of many genes has been described in regeneration, techniques for functional analysis have so far been limited. in this paper we demonstrate a new method for efficient overexpression of foreign genes in axolotls. using vaccinia virus expressing beta-galac ... | 2000 | 10656763 |
| apical epithelial cap morphology and fibronectin gene expression in regenerating axolotl limbs. | urodele amphibians (salamanders) are unique among adult vertebrates in their ability to regenerate limbs. the regenerated structure is often indistinguishable from the developmentally produced original. thus, the two processes by which the limb is produced - development and regeneration - are likely to use many conserved biochemical and developmental pathways. some of these limb features are also likely to be conserved across vertebrate families. the apical ectodermal ridge (aer) of the developi ... | 2000 | 10706145 |
| cloning and neuronal expression of a type iii newt neuregulin and rescue of denervated, nerve-dependent newt limb blastemas by rhggf2. | urodele amphibians are the only vertebrates that can regenerate their limbs throughout their life. the critical feature of limb regeneration is the formation of a blastema, a process that requires an intact nerve supply. nerves appear to provide an unidentified factor, known as the neurotrophic factor (ntf), which stimulates cycling of blastema cells. one candidate ntf is glial growth factor (ggf), a member of the neuregulin (nrg) growth factor family. nrgs are both survival factors and mitogens ... | 2000 | 10770844 |
| alteration of cardiac myofibrillogenesis by liposome-mediated delivery of exogenous proteins and nucleic acids into whole embryonic hearts. | a precise organization of contractile proteins is essential for contraction of heart muscle. without a necessary stoichiometry of proteins, beating is not possible. disruption of this organization can be seen in diseases such as familial hypertrophic cardiomyopathy and also in acquired diseases. in addition, isoform diversity may affect contractile properties in such functional adaptations as cardiac hypertrophy. the mexican axolotl provides an uncommon model in which to examine specific protein ... | 2000 | 10794163 |
| apoptosis in regenerating and denervated, nonregenerating urodele forelimbs. | denervated limbs of larval salamanders fail to regenerate if amputated and, unlike adult limbs, undergo regression. the cellular basis of the tissue loss is poorly understood. we used tunel staining of larval axolotl limbs fixed and sectioned at intervals after bilateral amputation and unilateral denervation to investigate the role of apoptosis during normal limb regeneration and denervated limb regression. in the first week after amputation a small percentage of apoptotic cells was found in bot ... | 2006 | 10810037 |
| analysis of cranial neural crest migratory pathways in axolotl using cell markers and transplantation. | we have examined the ability of normal and heterotopically transplanted neural crest cells to migrate along cranial neural crest pathways in the axolotl using focal dii injections and in situ hybridization with the neural crest marker, ap-2. dii labeling demonstrates that cranial neural crest cells migrate as distinct streams along prescribed pathways to populate the maxillary and mandibular processes of the first branchial arch, the hyoid arch and gill arches 1-4, following migratory pathways s ... | 2000 | 10821772 |
| elongation of axolotl tailbud embryos requires gpi-linked proteins and organizer-induced, active, ventral trunk endoderm cell rearrangements. | application of phosphatidylinositol-specific phospholipase c to early tailbud stage axolotl embryos reveals that a specific subset of morphogenetic movements requires glycosylphosphatidylinositol (gpi)-linked cell-surface proteins. these include pronephric duct extension, "gill bulge" formation, and embryonic elongation along the anteroposterior axis. the work of kitchin (1949, j. exp. zool. 112, 393-416) led to the conclusion that extension of the notochord provided the motive force driving ant ... | 2000 | 10864458 |
| all-trans-retinoic acid and all-trans-retinoyl-beta-d-glucuronide alter the development of axolotl embryos (ambystoma mexicanum) in vitro. | retinoids are involved in several physiological processes and are used in the treatment of various skin disorders. therapy with retinoids during pregnancy may induce severe embryotoxic effects like craniofacial and cardiovascular malformations in the developing embryo. we investigated the effects of all-trans-retinoic acid (atra) and all-trans-retinoyl-beta-d-glucuronide (atrag) in an amphibian embryotoxicity assay with ambystoma mexicanum (axolotl) as an alternative in vitro method. embryos wer ... | 2000 | 10877004 |
| rag expression is restricted to the first year of life in the mexican axolotl. | the developmental expression of the rag1 gene in the mexican axolotl hematopoietic organs was studied. rag1 mrnas were first detected in trunk extracts from 6-week-old larvae, and in head and trunk extracts of 8- and 9-week-old larvae. rag1 is expressed in the thymus at all stages of development, until its natural involution after 12 months of age. in contrast, although rag1 transcripts were present in the spleen and liver of the young larvae, they were not detected in the liver after 4.5 months ... | 2000 | 10941839 |
| evolutionary genetics of metamorphic failure using wild-caught vs. laboratory axolotls (ambystoma mexicanum). | in many organisms metamorphosis allows for an ecologically important habitat-shift from water to land. however, in some salamanders an adaptive life cycle mode has evolved that is characterized by metamorphic failure (paedomorphosis); these species remain in the aquatic habitat throughout the life cycle. perhaps the most famous example of metamorphic failure is the mexican axolotl (ambystoma mexicanum), which has become a focal species for developmental biology since it was introduced into labor ... | 2000 | 10972778 |
| directed axonal growth towards axolotl limb blastemas in vitro. | limb amputation in urodele amphibia is followed by formation of a blastema, which subsequently develops into a complete limb with normal pattern of innervation. in this study, we investigated the effects of axolotl limb blastemas on axonal growth in gels of collagen and extracellular matrix (matrigel). when peripheral nerves with attached dorsal root ganglia were cultured in collagen gels together with blastemas, axonal outgrowth was markedly increased compared with control preparations. blastem ... | 2000 | 10996470 |
| cloning of cdnas encoding retinoic acid receptors rar gamma 1, rar gamma 2, and a new splicing variant, rar gamma 3, from aambystoma mexicanum and characterization of their expression during early development. | to analyze retinoic acid (ra) receptor (rar) expression during early development in the urodele embryo, we have isolated cdnas for four members of the axolotl (ambystoma mexicanum) rar family, namely rar alpha (nr1b1), arar gamma 1 (nr1b3a), arar gamma 2 (nr1b3b), and a new splicing variant of arar gamma 2, arar gamma 3 (nr1b3c), which contains an insertion of five hydrophobic amino acids in the c-terminal region of the dna binding domain. the temporal expression pattern of the rar gamma isoform ... | 2000 | 11004482 |
| candidate gene analysis of thyroid hormone receptors in metamorphosing vs. nonmetamorphosing salamanders. | we used two different experimental approaches to test the hypothesis that thyroid hormone receptor (tr) variation is associated with alternate life cycles modes in ambystomatid salamanders. in the first experiment, the inheritance of tralpha and trbeta genotypes was determined for metamorphic and non metamorphic offspring from backcrosses between ambystoma mexicanum (an obligate metamorphic-failure species) and metamorphic f1 hybrids (a. mexicanum x a. tigrinum tigrinum). the segregation of tr g ... | 2000 | 11012711 |
| matrix metalloproteinase production in regenerating axolotl spinal cord. | in urodele amphibian spinal cord regeneration, the ependymal cells lining the central canal remodel the lesion site to favor axonal regrowth. we profiled the production of matrix metalloproteinases by injury-reactive mesenchymal ependymal cells in vivo and in vitro and found that matrix metalloproteinases are involved in this remodeling process in the axolotl (ambystoma mexicanum). the production of cell-associated matrix metalloproteinases in vivo was shown to be identical to that in our cultur ... | 2006 | 11013020 |
| expression of the cardiac actin gene in axolotl embryos. | axolotis are an important model system for studying heart development. patterning of the somitic mesoderm occurs in axolotis in a manner that is much more similar to the pattern observed in higher vertebrates than in xenopus. for these reasons we cloned the axolotl cardiac actin gene, since this gene is expressed during the development of both somitic and cardiac muscle in other vertebrates. in this paper we characterize its expression. expression of cardiac actin rna is switched on during gastr ... | 2000 | 11032182 |
| the odontoclasts of ambystoma mexicanum. | the resorption of teeth in ambystoma mexicanum during postembryonal ontogenesis and induced metamorphosis occurs by means of light-microscopic detectable giant-cells. these have morphological and functional characters similar to those of odontoclasts of other vertebrates. the multinucleated odontoclasts resorb not only the pedicel (base), but the stalk of the tooth, too. when active, the cells form a ruffled border and a sealing zone. in this way they are able to demineralize the hard tissues of ... | 2000 | 11035635 |
| [dynamics of the intensity of respiration in early embryogenesis of amphibians]. | we studied growth and respiration rate during early ontogenesis of the axolotl ambystoma mexicanum, bosca's newt triturus waltlii, the green toad bufo viridis, and the smooth clawed frog xenopus laevis. the respiration rate in these amphibian species increases during embryonal and larval development, peaks after transition to active feeding, and decreases at later stages of ontogenesis. the patterns of dynamics of this energy metabolism index in tailed and tailless amphibians have some differenc ... | 2000 | 11036669 |
| interruption of cardiac output does not affect short-term growth and metabolic rate in day 3 and 4 chick embryos. | the heart beat of vertebrate embryos has been assumed to begin when convective bulk transport by blood takes over from transport by simple diffusion. to test this hypothesis, we measured eye growth, cervical flexure and rates of oxygen consumption ( v(o2)) in day 3-4 chick embryos denied cardiac output by ligation of the outflow tract and compared them with those of embryos with an intact cardiovascular system. eye diameter, used as the index for embryonic growth, increased at a rate of approxim ... | 2000 | 11076745 |
| gdnf and gfralpha-1 are components of the axolotl pronephric duct guidance system. | in mammals, secretion of gdnf by the metanephrogenic mesenchyme is essential for branching morphogenesis of the ureteric bud and, thus, metanephric development. however, the expression pattern of gdnf and its receptor complex-the gpi-linked ligand-binding protein, gfralpha-1, and the ret tyrosine kinase signaling protein-indicates that it could operate at early steps in kidney development as well. furthermore, the developing nephric systems of fish and amphibian embryos express components of the ... | 2000 | 11087631 |
| immunohistochemical demonstration of hyaluronan and its possible involvement in axolotl neural crest cell migration. | hyaluronan (ha), an extracellular matrix component, is involved mainly in the control of cell proliferation, neural crest and tumor cell migration, and wound repair. we investigated the effect of hyaluronan on neural crest (nc) cell migration and its ultrastructural localization in dark (wild-type) and white mutant embryos of the mexican axolotl (ambystoma mexicanum, amphibia). the axolotl system is an accepted model for studying mechanisms of nc cell migration. using a biotinylated hyaluronan b ... | 2000 | 11121304 |
| distribution and innervation of taste buds in the axolotl. | adult axolotls have approximately 1,400 taste buds in the epithelium of the pharyngeal roof and floor and the medial surfaces of the visceral bars. these receptors are most dense on the lingual surfaces of the upper and lower jaws, slightly less dense throughout lateral portions of the pharyngeal roof and floor, and more sparse within medial portions of the pharyngeal roof and floor, except for a median oval patch of receptors located rostrally between the vomerine tooth fields. each taste bud i ... | 2000 | 11124515 |
| structure and diversity of mexican axolotl lambda light chains. | we report here the structure of cdna clones encoding axolotl light chains of the lambda type. a single iglc gene and eight different potential iglv genes belonging to four different families were detected. the axolotl cgamma domain has several residues or stretches of residues that are typically conserved in mammalian, avian, and xenopus cgamma, but the katlvcl stretch, which is well conserved in the cgamma and t-cell receptor cbeta domains of many vertebrate species, is not well conserved. all ... | 2000 | 11132150 |
| expression patterns of fgf-8 during development and limb regeneration of the axolotl. | fgf-8 is one of the key signaling molecules implicated in the initiation, outgrowth, and patterning of vertebrate limbs. however, it is not clear whether fgf-8 plays similar role in development and regeneration of urodele limbs. we isolated a fgf-8 cdna from the mexican axolotl (ambystoma mexicanum) through the screening of an embryo cdna library. the cloned 1.26-kb cdna contained an open reading frame encoding 212 amino acid residues with 84%, 86%, and 80% amino acid identities to those of xeno ... | 2001 | 11146506 |
| expression of hoxb13 and hoxc10 in developing and regenerating axolotl limbs and tails. | the expression of hox complex genes in correct spatial and temporal order is critical to patterning of the body axis and limbs during embryonic development. in order to understand the role such genes play in appendage regeneration, we have compared the expression of two 5' hox complex genes: hoxb13 and hoxc10 during development and regeneration of the body axis and the limbs of axolotls. in contrast to higher vertebrates, hoxb13 is expressed not only in the tip of the developing tail, but also i ... | 2001 | 11150241 |
| ontogeny of neurohormonal peptides, serotonin, and nitric oxide synthase in the gastrointestinal neuroendocrine system of the axolotl (ambystoma mexicanum): an immunohistochemical analysis. | the ontogeny of the neurohormonal peptides vasoactive intestinal polypeptide (vip), neurotensin (nt), substance p (sp), calcitonin gene-related peptide (cgrp), gastrin/cholecystokinin (gas/cck), and somatostatin (som) as well as serotonin (ser) and nitric oxide synthase (nos) was investigated in the gastrointestinal tract of the urodele ambystoma mexicanum, the axolotl, using immunohistochemical techniques. the first regulatory substances to appear were sp, som, and ser that could be immunohisto ... | 2001 | 11161772 |
| development and regulation of response properties in spinal cord motoneurons. | the intrinsic response properties of spinal motoneurons determine how converging premotor neuronal input is translated into the final motor command transmitted to muscles. from the patchy data available it seems that these properties and their underlying currents are highly conserved in terrestrial vertebrates in terms of both phylogeny and ontogeny. spinal motoneurons in adults are remarkably similar in many respects ranging from the resting membrane potential to pacemaker properties. apart fro ... | 2000 | 11165788 |
| complexity of the t cell receptor cbeta isotypes in the mexican axolotl: structure and diversity of the vdjcbeta3 and vdjcbeta4 chains. | we have reported previously the presence of two t cell receptor beta-chain constant region (cbeta) isotypes in the mexican axolotl. specific dbeta and jbeta segments were present at the vbeta-cbeta1 and vbeta-cbeta2 junctions and nine vbeta families which associate with both isotypes were characterized. this report describes two new cbeta isotypes, cbeta3 and cbeta4. about 70 % of the amino acids in cbeta3 are identical to cbeta1 and cbeta2. a dbeta3 and a single jbeta3 were found at the vbeta-c ... | 2001 | 11180104 |
| axolotl mhc class ii beta chain: predominance of one allele and alternative splicing of the beta1 domain. | the axolotl mhc is composed of multiple polymorphic class i loci linked to class ii b loci. in this report, evidence of the existence of one class ii b locus (amme-dab) that codes for two different transcripts is given. a 2.1-kb transcript is translated to a complete beta chain and a shorter transcript of 1.8 kb encodes a molecule lacking the beta1 domain. for two complete class ii b mrna synthesized, up to one mrna devoid of the beta1 domain is synthesized. alternative splicing involving a pept ... | 2001 | 11180116 |
| expression and characterization of fibroblast growth factor 8 from mexican axolotl, ambystoma mexicanum. | fibroblast growth factor (fgf) has been known to regulate the proliferation and differentiation of a variety of cell types via interaction with a specific fgf receptor on the cell surface. in the present study, fgf8 cdna of mexican axolotl, ambystoma mexicanum, was expressed in escherichia coli as an mbp-fgf8 fusion protein. the cell proliferation activity of the recombinant fgf8 (rfgf8) was measured by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazoliumbromide (mtt) assay. the addition of r ... | 2000 | 11211874 |
| nitric oxide in the afferent synaptic transmission of the axolotl vestibular system. | this study was performed using intracellular and multiunit extracellular recording techniques in order to characterize the role of nitric oxide in the afferent synaptic transmission of the vestibular system of the axolotl (ambystoma tigrinum). bath application of nitric oxide synthase inhibitors n(g)-nitro-l-arginine (0.01microm to 10microm) and n-nitro-l-arginine methyl ester hydrochloride (0.1microm to 1000microm) elicited a dose-dependent decrease in the basal discharge of the semicircular ca ... | 2001 | 11246160 |