| survey of the numbers and species of amphibia used in the united kingdom in 1977. | this survey suggests that about 115 000 amphibia, of which more than half were rana temporaria, were supplied for use in teaching and research in the uk during 1977. as only 27 000 were recorded as being used by universities, polytechnics and research institutes, probably mostly for teaching, it must be assumed that the majority are used for teaching purposes in schools. there has been an increase in the proportion of amphibia supplied by recognised suppliers, and also in that being 'purpose-bre ... | 1980 | 6965743 |
| thymus dependency in anti-trinitrophenyl (tnp) binding responses in the spleen of ambystoma mexicanum. effects of thymectomy and anti-thymocyte serum treatments. | | 1981 | 6970685 |
| an atlas of notochord and somite morphogenesis in several anuran and urodelean amphibians. | a scanning electron microscopic, comparative survey of notochord and somite formation including some details of change in cell morphology and arrangement, was made of selected stages of two species of anuran amphibians (xenopus laevis and rana pipiens) and two species of urodeles (ambystoma mexicanum and pleurodeles waltlii). the ectoderm or neural plate was removed from fixed embryos and the dorsal aspect of the developing notochord and somite mesoderm was photographed. micrographs of comparabl ... | 1980 | 6971322 |
| [histochemical study of the cholinesterases of various formations of the vertebrate endbrain]. | histochemical studies have been made on true (ache) and false (bche) cholinesterases in different parts of the telencephalon of amphibians, reptiles and mammals. the data obtained indicate that the enzymic localization depends on both the level of the development of the brain and phylogenetic age of its individual formations. in the telencephalon of ambystoma mexicanum, high concentration of ache was found in vascular-capillary network, in other investigated amphibians (triturus vulgaris, rana t ... | 1981 | 6976662 |
| regulation of antibody synthesis in the x-irradiated mexican axolotl. | the effects of x-irradiation were studied on the mexican axolotl antibody synthesis. to reduce the anti-horse red blood cell (hrbc) antibody titers, 150 rd and smaller doses are ineffective, 200-450 rd are increasingly effective, and 700 rd are maximally effective (and lethal). a significant enhancement of the anti-hrbc titers was observed in low doses (50-150 rd x-irradiated animals). this enhancement was also observed when a low x-ray dose was applied only on the thymic areas. in whole body, b ... | 1981 | 7028489 |
| evidence for low-molecular weight antibodies in the serum of a urodele amphibian, ambystoma mexicanum. | adult axolotls (a. mexicanum) were hyperimmunized with the haptenic determinant, azobenzene-arsonate (ars). specific antibodies were isolated from their serum by immune-affinity chromatography on immobilized ars columns. analysis of the specific ars-binding molecules by sodium dodecyl sulfate polyacrylamide gel electrophoresis (sds-page) indicated that these animals were capable of producing both high molecular-weight (presumably igm) and low molecular-weight antibodies to the ars hapten. the lo ... | 1982 | 7061117 |
| corticosteroid action on lymphocyte subpopulations and humoral immune response of axolotl (urodele amphibian). | the effect of in vivo hydrocortisone (hc) treatment on thymocytes, splenic and blood lymphocytes and on allogeneic and humoral immune responses were investigated in the axolotl (urodele amphibian). hc induces a profound lymphocytopenia in the thymus (83% hc sensitive) and the spleen (50% hc sensitive) but not in the blood. the density gradient analysis of hc-treated axolotls showed that thymic cell populations of light density were more sensitive than populations of high density. the timing of h ... | 1982 | 7076277 |
| peaks of neuronal membrane antigen and thyroxine in larval development of the mexican axolotl. | | 1982 | 7160616 |
| a variant cardiac tropomyosin in the salamander, ambystoma mexicanum. | | 1982 | 7182078 |
| the movement of the prospective eye vesicles from the neural plate into the neural fold in ambystoma mexicanum and xenopus laevis. | | 1981 | 7286445 |
| an interaction between dorsal and ventral regions of the marginal zone in early amphibian embryos. | when small explants from early gastrulae of xenopus laevis are allowed to develop in a buffered salt solution there is a considerable difference between the patterns of differentiation obtained from different dorsoventral levels of the marginal zone. these patterns of differentiation correspond to the fates of the different regions in the course of normal development. they are not altered if several explants of the same type are fused before culture. if a ventral marginal zone explant from xenop ... | 1980 | 7400747 |
| dominant lethal induction by ethyl methanesulfonate in the male axolotl (ambystoma mexicanum). | when male axolotls (ambystoma mexicanum) were treated with ethyl methanesulfonate (ems) and mated at regular intervals thereafter, the incidence of embryonic abnormalities among the f1 progeny increased until a time was reached when none survived to hatching. at 100 mg/1 ems, this point was reached about 130 days after treatment. thereafter, the frequency of abnormalities gradually decreased to control levels. at higher concentrations, abnormalities were seen in spawnings obtained sooner after t ... | 1980 | 7462966 |
| expression of a p0-like glycoprotein in central nervous system myelin of amphibians (ambystoma mexicanus, xenopus laevis and rana catesbeiana). | 1. the myelin protein profiles in the cns and pns of three species of amphibians were analyzed by biochemical and immunohistochemical methods. 2. the cns myelin of the african clawed frog (xenopus) and the mexican salamander (axolotl) contained, in addition to proteolipid protein, a unique protein zero (p0)-like protein, whereas the adult bullfrog did not. 3. a strong expression of the p0-like protein in the bullfrog cns myelin was found transiently at ontogenetically early phases including at t ... | 1993 | 7507810 |
| noradrenergic and peptidergic innervation of the amphibian spleen: comparative studies. | spleens from representatives of the three amphibian orders were examined using sucrose-potassium phosphate-glyoxylic acid (spg) histofluorescence to detect catecholamines and immunocytochemistry to detect several neural antigens. nerve fibers are scattered throughout the spleens of adult salamanders (taricha torosa, notophthalmus viridescens, and ambystoma mexicanum). a less abundant but similarly diffuse pattern of innervation characterizes the spleen of the caecilian, typhlonectes sp. the sple ... | 1994 | 7539385 |
| identification and expression of a homologue of the murine hoxa5 gene in the mexican axolotl (ambystoma mexicanum). | an excellent model for studying heart development in vertebrates is the cardiac non-function lethal mutant (gene c) mexican axolotl, ambystoma mexicanum. in order to facilitate our analyses of the mutant system, we have undertaken a search for stage-specific molecular markers during embryonic development of the axolotl. we have concentrated on homeobox genes as suitable candidates for monitoring molecular changes during development. a 270-bp probe encoding a portion of the axolotl homeobox gene ... | 1995 | 7557438 |
| a "minimal essential mhc" and an "unrecognized mhc": two extremes in selection for polymorphism. | the high polymorphism of classical mhc molecules found in mammals is not simply the result of strong selection for pathogen resistance in the recent past, since there are virtually no examples of diseases caused by infectious pathogens for which resistance is determined by particular mhc haplotypes, and in the best-studied case, a particular aspect of malaria in humans, the selection is remarkably weak. we discuss three possibilities to explain high polymorphism in mammals: accumulating, merging ... | 1995 | 7558083 |
| regulation of hoxa expression in developing and regenerating axolotl limbs. | homeobox genes are important in the regulation of outgrowth and pattern formation during limb development. it is likely that homeobox genes play an equally important role during limb regeneration. we have isolated and identified 17 different homeobox-containing genes expressed by cells of regenerating axolotl limbs. of these, nearly half of the clones represent genes belonging to the hoxa complex, which are thought to be involved in pattern formation along the proximal-distal limb axis. in this ... | 1995 | 7600989 |
| erratic deposition of agrin during the formation of xenopus neuromuscular junctions in culture. | in order to disclose the mechanism that regulate synapse development we compared the distributions of agrin, acetylcholine receptors (achr) and a basal lamina heparan sulfate proteoglycan (hspg) in sections and cultures prepared from xenopus laevis and ambystoma mexicanum embryos. while agrin, achr and hspg may accumulate almost synchronously at synapses in vivo, agrin deposition usually lagged well behind the other synaptic markers during development in culture, and was not detectable at many d ... | 1995 | 7601300 |
| cloning, sequencing and expression of an isoform of cardiac c-protein from the mexican axolotl (ambystoma mexicanum). | c-protein, a myosin binding protein, is thought to regulate and stabilize thick filaments during assembly of sarcomeric a-bands. multiple isoforms of c-protein have been characterized in avian and mammalian systems. we now report the isolation and the nucleic acid sequence of a partial c-protein cdna clone from an axolotl heart cdna expression library in lambda gt11. the clone was isolated by screening the library with a heterologous monoclonal anti-c-protein antibody (mf1). sequence comparison ... | 1995 | 7639739 |
| amphibian micronucleus test(s): a simple and reliable method for evaluating in vivo genotoxic effects of freshwater pollutants and radiations. initial assessment. | a micronucleus test was developed using larvae from two urodele amphibians (pleurodeles waltl and ambystoma mexicanum) and an anuran (xenopus laevis). the methods for maintenance of adults, egg laying, and rearing the larvae are described, and the conditions required for optimal response are given for each of these species. the tests are carried out during a period of intense erythropoiesis when red blood cells are actively dividing in circulating blood. the micronuclei are observed on blood sme ... | 1993 | 7688100 |
| production and characterization of polyclonal antibodies against awnt-1, the axolotl homologue of the proto-oncogene product wnt-1. | the proto-oncogene wnt-1 (int-1) is activated by mouse mammary tumor virus retroviral insertion and contributes to the formation of mammary gland tumors in mice. during early development, it is expressed in small groups of cells in the developing central nervous system of fish, amphibians and mice. in the ambystoma mexicanum (axolotl) embryo, the expression profile of wnt-1 is biphasic. we have raised polyclonal antibodies against a synthetic peptide corresponding to a surface-exposed epitope of ... | 1993 | 7691335 |
| expression of pax-6 during urodele eye development and lens regeneration. | regeneration of eye tissues, such as lens, seen in some urodeles involves dedifferentiation of the dorsal pigmented epithelium and subsequent differentiation to lens cells. such spatial regulation implies possible action of genes known to be specific for particular cell lineages and/or axis. hox genes have been the best examples of genes for such actions. we have, therefore, investigated the possibility that such genes are expressed during lens regeneration in the newt. the pax-6 gene (a gene th ... | 1995 | 7761453 |
| the identification and partial cloning by pcr of the gene for tyrosinase-related protein-1 in the mexican axolotl. | the tyrosinase gene family is currently composed of three members, tyrosinase and two tyrosinase-related proteins, trp-1 and trp-2. these three gene products have all been found to act in the synthesis of melanin pigments with the enzyme tyrosinase catalyzing the initial rate-limiting steps. thus far these genes have primarily been analyzed in higher vertebrates. we have used degenerate pcr primers to isolate a large fragment of an axolotl tyrosinase-related protein. sequence analysis of the ent ... | 1995 | 7792254 |
| the evolution of efferent vagal control of the heart in vertebrates. | in vertebrates vagal preganglionic neurons are found in two principle locations in the brain-stem, the dorsal vagal motor nucleus and areas lateral to the dorsal vagal motor nucleus centered on the nucleus ambiguus. in elasmobranch fish 8% of vagal preganglionic neurons are located outside the dorsal vagal motor nucleus; these are all cardiac vagal motoneurones. this proportion increases from fish through amphibians to mammals in which over 30% of vagal preganglionic neurons are outside the dors ... | 1994 | 7827254 |
| expression of the axolotl homologue of mouse chaperonin t-complex protein-1 during early development. | molecular chaperones assist in the folding of proteins, but their role during development is not well understood. here we report the temporal and spatial expression pattern of the axolotl homologue of mouse chaperonin tcp-1 during normal amphibian embryogenesis and in several models of abnormal embryogenesis. a partial axolotl tcp-1 cdna (646 bp; 519 coding bp) isolated by 3' race pcr shows considerable homology to mouse tcp-1. developmental northerns and rt-pcr analyses of whole axolot1 embryos ... | 1995 | 7841192 |
| the third component of xenopus complement: cdna cloning, structural and functional analysis, and evidence for an alternate c3 transcript. | although the third component of complement has been purified from two amphibian species, xenopus laevis and the axolotl, only limited information is available about its primary structure in these species. we now present (a) 95% of the cdna sequence encoding c3 from a xenopus laevis/xenopus gilli (xenopus lg) hybrid (b) an analysis of the c3 convertase and factor i cleavage sites in xenopus c3, and (c) evidence for an alternative form of c3. the xenopus lg sequence has a 57% nucleotide and 52% am ... | 1995 | 7875221 |
| structure of the major neutral oligosaccharide-alditols released from the egg jelly coats of axolotl maculatum. characterization of the carbohydrate sequence galnac(beta 1-4)[fuc(alpha 1-3)] glcnac(beta 1-3/6). | several o-linked oligosaccharides of the jelly coat surrounding the eggs of axolotl maculatum were analysed by 1h-nmr spectroscopy. the four major oligosaccharidealditols released by reductive beta-elimination display either the lewisx (lex) determinant or the sequence galnac(beta 1-4)[fuc(alpha 1-3)]glcnac. this last structure has previously been characterized in allergenically active oligosaccharides isolated from the sea squirt h-antigen, and in the n-linked glycans of schistosoma mansoni and ... | 1994 | 7881174 |
| [characterization of cdna of t-cell receptor beta chain in rainbow trout]. | using a two-step pcr strategy, we have cloned several cdna segments encoding the t-cell receptor beta chain in a teleost fish, the rainbow trout (oncorhynchus mykiss). the nine clones analyzed encode identical n-terminal-truncated v beta regions which present limited sequence similarities with several mammalian tcr v beta chains, from residue tyr-35 to residue ser-95. these v beta regions are followed by v beta-d beta-j beta-like regions which are different in all the sequenced clones, and by id ... | 1994 | 7882160 |
| evolution of t cell receptor genes. extensive diversity of v beta families in the mexican axolotl. | we have cloned 36 different rearranged variable regions (v beta) genes encoding the beta-chain of the t cell receptor in an amphibian species, ambystoma mexicanum (the mexican axolotl). eleven different v beta segments were identified, which can be classified into 9 families on the basis of a minimum of 75% nucleotide identity. all the cloned v beta segments have the canonical features of known mammalian and avian v beta, including conserved residues cys23, trp34, arg69, tyr90, and cys92. there ... | 1994 | 7963525 |
| evolutionary conservation and molecular cloning of the recombinase activating gene 1. | a 700-bp fragment of the recombinase activating gene 1 (rag-1) was cloned from several evolutionarily distant (sandbar shark, paddlefish, goldfish, axolotl and pig) species using pcr. the nucleotide and deduced amino acid sequences revealed a highly conserved region that has remained essentially unaltered during 400 million years of evolution; e.g., shark and human sequences were 75% identical at the nucleic acid level and 87% as protein. the rag-1 mrna levels in the shark were analyzed using se ... | 1994 | 7999099 |
| cloning and expression of the axolotl proto-oncogene ski. | in vitro and in vivo overexpression studies have demonstrated that the c-ski proto-oncogene can influence proliferation, morphological transformation and myogenic differentiation. we report the isolation and expression of an axolotl (ambystoma mexicanum) c-ski (aski) gene. sequence analysis revealed a high degree of nucleotide and predicted amino acid (aa) homology with mammalian and anuran c-ski, showing the highest conservation to xenopus laevis c-ski (74% nucleotide and 87% aa). northern anal ... | 1995 | 7999783 |
| mitogen-activated axolotl (ambystoma mexicanum) splenocytes produce a cytokine that promotes growth of homologous lymphoblasts. | culture supernatants (pha-sns) from axolotl splenocytes cultured with phytohemagglutinin-p (pha) in medium supplemented with bovine serum albumin (bsa) were collected after 1, 2, and 3 days, pooled, treated to remove residual pha, precipitated with saturated ammonium sulfate, dialyzed, aliquoted, and stored at -20 degrees c. pha-sns stimulated proliferation of homologous lymphoblasts, but not resting splenocytes. sds-page of metabolically labeled pha-sns revealed a band between 14 and 21 kda. th ... | 1994 | 8001702 |
| multiple embryonic origins of gonadotropin-releasing hormone (gnrh) immunoreactive neurons. | experiments were conducted to test the hypothesis that gonadotropin-releasing hormone immunoreactive (gnrh-ir) and fmrfamide-ir neurons present in the brain and nervus terminalis originate in the embryonic olfactory placode. the olfactory placodes were bilaterally extirpated in stage 26 or stage 29 embryos of the axolotl, ambystoma mexicanum, which were then reared for 4-8 months before they were examined immunohistochemically. in experimental subjects with bilateral loss of olfactory epithelia, ... | 1994 | 8026083 |
| molecular cloning, sequencing and expression of an isoform of cardiac alpha-tropomyosin from the mexican axolotl (ambystoma mexicanum). | the cdna for alpha-tropomyosin (tm) was cloned by the polymerase chain reaction (pcr) from a lambda gt11 library constructed with mrna from juvenile axolotl heart tissues. subsequently, the nucleotide sequence of the cdna was determined. this is the first reported cdna for axolotl alpha-tropomyosin. comparative analyses of the deduced amino acid sequence of this cdna with xenopus skeletal muscle alpha-tropomyosin sequences indicate that the axolotl heart cdna has 93% and 96% homology in the regi ... | 1994 | 8074673 |
| plasma potassium may protect sodium pumps of toad hearts from an endogenous inhibitor. | resibufogenin (3-hydroxy-14,15-epoxy-20,22-dienolide glycoside) is a potent sodium pump inhibitor present in toad toxin. it is present in the skin of the cane toad (bufo marinus) at a concentration equivalent to ouabain of approximately 1 mm. because toads, like other amphibians, have permeable skin, resibufogenin is also found in high concentrations in the blood. in the cane toad the blood concentration is estimated to be 1 microm (d. lichtstein, s. kachalsky, and j. deutsch. life sci. 38: 1261 ... | 1994 | 8092319 |
| retinoic acid gradients during limb regeneration. | retinoids have been implicated in pattern formation processes in both developing chick limbs and in the regenerating limbs of urodele amphibians as well as in other aspects of embryonic development. since chick wing buds have been shown to have a higher concentration of all-trans-retinoic acid (ra) in the posterior region than in the anterior region, we set out to look for a gradient of ra in the regenerating limb of the axolotl, ambystoma mexicanum. we used high-performance liquid chromatograph ... | 1994 | 8150219 |
| characterization of a multimeric polypeptide complex on the surface of thymus-derived cells in the mexican axolotl. | we previously raised a rabbit antiserum (l12) against a 38 kd polypeptide which is expressed on the surface of thymocytes and peripheral t cells of an urodele amphibian, the mexican axolotl (ambystoma mexicanum). here we show that l12 antibodies immunoprecipitate several labelled molecules from surface iodinated axolotl spleen cells, including the 38 kd molecule, but also two polypeptides of 43 and 22 kd which are covalently linked to other elements. another rabbit antiserum (l10) was raised aga ... | 1993 | 8211000 |
| receptors for atrial natriuretic factor (anf) in kidney and adrenal tissue of urodeles--lack of angiotensin ii (a ii) receptors in these tissues. | binding sites for atrial natriuretic factor (anf) and angiotensin ii (a ii) were localized and quantified in renal and adrenal tissue of the urodele ambystoma mexicanum by quantitative in vitro autoradiography using 125i-ratanf(99-126) and 125i-[val5]-a ii or 125i-human a ii as labeled ligands. specific 125i-ratanf(99-126) binding was present in glomeruli, renal tubules, and adrenal tissue. anf had heterogeneous binding sites exhibiting positive cooperativity with a half maximal binding concentr ... | 1993 | 8224766 |
| hormone-induced rise in cytosolic ca2+ in axolotl hepatocytes: extracellular origin and control by camp. | in amphibian liver, signal transduction of [arg8]vasotocin (avt), a "classical" ca(2+)-dependent hormone in rat liver, is mediated via the generation of adenosine 3',5'-cyclic monophosphate (camp) and not via inositol 1,4,5-trisphosphate [ins(1,4,5)p3]. in isolated hepatocytes from axolotl, hormones that stimulated camp formation (the order of efficacy was glucagon > isoprenaline > epinephrine > or = avt) also provoked a pronounced increase in cytosolic ca2+, as indicated from changes in fura 2 ... | 1993 | 8238480 |
| conserved structure of amphibian t-cell antigen receptor beta chain. | all jawed vertebrates possess well-differentiated thymuses and elicit t-cell-like cell-mediated responses; however, no surface t-cell receptor (tcr) molecules or tcr genes have been identified in ectothermic vertebrate species. here we describe cdna clones from an amphibian species, ambystoma mexicanum (the mexican axolotl), that have sequences highly homologous to the avian and mammalian tcr beta chains. the cloned amphibian beta chain variable region (v beta) shares most of the structural char ... | 1993 | 8341702 |
| phylogeny of immunoglobulin heavy chain isotypes: structure of the constant region of ambystoma mexicanum upsilon chain deduced from cdna sequence. | an rna polymerase chain reaction strategy was used to amplify and clone a cdna segment encoding for the complete constant part of the axolotl igy heavy (c upsilon) chain. c upsilon is 433 amino acids long and organized into four domains (c upsilon 1-c upsilon 4); each has the typical internal disulfide bond and invariant tryptophane residues. axolotl c upsilon is most closely related to xenopus c upsilon (40% identical amino acid residues) and c upsilon 1 shares 46.4% amino acid residues among t ... | 1993 | 8344718 |
| immunocytochemical identification of serotonin-synthesizing neurons in the vertebrate retina: a comparative study. | serotonin-synthesizing neurons in the retinas of goldfish, axolotl, turtle, chick, rabbit and cat were identified using double labelling with anti-serotonin and anti-phenylalanine hydroxylase antibodies. the latter antibody recognizes tryptophan 5-hydroxylase, one of the synthesizing enzymes for serotonin. neurons labelled by both markers were considered to be serotonin-synthesizing neurons, while those only with serotonin-immunoreactivity were assumed to be serotonin-accumulating neurons. in th ... | 1993 | 8462655 |
| immunohistochemical analysis of c-protein isoforms in cardiac and skeletal muscle of the axolotl, ambystoma mexicanum. | of the several proteins located within sarcomeric a-bands, c-protein, a myosin binding protein (mybp) is thought to regulate and stabilize thick filaments during assembly. this paper reports the characterization of c-protein isoforms in juvenile and adult axolotls, ambystoma mexicanum, by means of immunofluorescent microscopy and western blot analyses. c-protein and myosin are found specifically within the a-bands, whereas tropomyosin and alpha-actin are detected in the i-bands of axolotl myofib ... | 1995 | 8581934 |
| the epidermis is a source of directional information for the migrating pronephric duct in ambystoma mexicanum embryos. | in the urodele ambystoma mexicanum, the pronephric duct (pnd) is formed from a coherent group of cells that migrate from the pronephros to the cloaca along a pathway immediately ventral to the developing somites. the guidance cues used by the migrating pnd primordium to find the cloaca are a local property of the migration substratum, are temporally regulated, and are both polarized and oriented. since the pronephric duct migrates between two tissues--the underlying lateral mesoderm and the over ... | 1995 | 8612962 |
| neural crest cell migration and pigment pattern formation in urodele amphibians. | this review deals with research on the development and differentiation of the neural crest (nc) in amphibians carried out during the past twenty years. first, earlier studies on the migration and differentiation of nc cells in vitro are summarized. these studies include the modes of nc cell migration and their differentiation into chondroblasts, perichondral cells, neurons, schwann cells and pigment cells (melanophores and xanthophores). then a summary is given on the development of cranial sens ... | 1996 | 8735933 |
| nucleotide sequence and expression of ribosomal protein s3 mrna during embryogenesis in the mexican axolotl (ambystoma mexicanum). | we have isolated and sequenced a full-length (0.9 kb) cdna clone of ribosomal protein s3 by subtraction hybridization using a single-stranded cdna library from stage 25-27 (tracer) and the mrna from stage 15-17 (driver) of embryonic mexican axolotl (ambystoma mexicanum). the axolotl is a unique animal model for studying heart development as well as myofibrillogenesis because it carries a mutation in gene c. the deduced amino acid sequence of axolotl s3 protein shows about 93.9% identity with hum ... | 1996 | 8739028 |
| effects of extracellular matrix molecules on subepidermal neural crest cell migration in wild type and white mutant (dd) axolotl embryos. | migration of neural crest (nc) derived pigment cells is restricted in the white mutant (dd) axolotl embryo (ambystoma mexicanum). transplantations between mutant and wild type embryos show that the extracellular matrix (ecm) of the white mutant is unable to support the migration of prospective pigment cells in wild type embryos (löfberg et al., 1989, dev. biol. 131:168-181). in the present study, we test the effects of various purified ecm molecules on nc cell migration in the subepidermal migra ... | 1996 | 8739557 |
| surface contraction and expansion waves correlated with differentiation in axolotl embryos. ii. in contrast to urodeles, the anuran xenopus laevis does not show furrowing surface contraction waves. | we have observed a number of contraction waves traversing the axolotl (ambystoma mexicanum) embryo (a urodelan amphibian) from the midblastula transition up to at least neural tube closure, and wished to learn if similar "differentiation waves" appear on the popular laboratory anuran amphibian, the south african clawed toad, xenopus laevis. time lapse video microscopy showed that no contraction waves are visible on the surface of xenopus from gastrulation through neurulation. it is possible that ... | 1996 | 8877438 |
| morphogenesis of the axolotl pronephric duct: a model system for the study of cell migration in vivo. | pronephric duct (pnd) morphogenesis is a critical early event in the development of the vertebrate excretory system. this structure is the exit channel for both pronephric and mesonephric filtrate, forms the ureteric bud of the metanephros and gives rise to the ductus deferens of the testis. in addition, the pnd and ureteric bud epithelia induce terminal differentiation of the mesonephric and metanephric mesenchyme, respectively. elongation of the pnd in all vertebrates involves active cell migr ... | 1996 | 8877443 |
| lens induction in axolotls: comparison with inductive signaling mechanisms in xenopus laevis. | amphibian lens induction is an embryonic process whose broad outlines are conserved between anurans and urodeles; however, it has been argued that some aspects of this process differ significantly between even closely related species. classical embryologists concluded that in some species direct contact between the optic vesicle and ectoderm was both necessary and sufficient to induce the ectoderm to form a lens, while in other species tissues other than the optic vesicle induce lens formation. ... | 1996 | 8877449 |
| structure and diversity of the t-cell receptor alpha chain in the mexican axolotl. | polymerase chain reaction was used to isolate cdna clones encoding putative t-cell receptor (tcr) alpha chains in an amphibian, the mexican axolotl (ambystoma mexicanum). five tcralpha-v chain-encoding segments were identified, each belonging to a separate family. the best identity scores for these axolotl tcralpha-v segments were all provided by sequences belonging to the human tcralpha-v1 family and the mouse tcralpha-v3 and tcralpha-v8 families. a total of 14 different tcra-j segments were id ... | 1997 | 9002443 |
| analysis of the three-dimensional distributions of alpha-actinin, ankyrin, and filamin in developing hearts of normal and cardiac mutant axolotls (ambystoma mexicanum). | alpha-actinin is an actin binding protein that assists in the stabilization of the plasma membrane and helps to fix organelles in position in a variety of cell types. in muscle, it is a major component of the z-lines of organized myofibrils. ankyrin binds to various elements of the cytoskeletal system including microtubules, microfilaments, and intermediate filaments and may help to anchor these structures to the cell membrane. filamin is a well-characterized actin-associated protein first isola ... | 1997 | 9045985 |
| evidence for the presence and participation of 85-75 kda extracellular matrix components in cell interactions of bufo arenarum gastrulation. | we studied the presence and distribution of the extracellular materials (ecm), obtained by mild embryonic dissociation through nondenaturing and denaturing page, immunoblotting and immunocytochemical wholemount in the gastrulation of anuran amphibian bufo arenarum. the sds-page, under reducing conditions, revealed the protein profile of the ecm which comprised six bands. the western immunoblotting effected with antibodies against fibronectins (fn) of xenopus laevis, ambystoma mexicanum and bufo ... | 1997 | 9062995 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| [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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| [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 |
| 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 |
| 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 |
| evidence for multiple sequences and factors involved in c-myc rna stability during amphibian oogenesis. | to investigate the molecular mechanisms regulating c-myc rna stability during late amphibian oogenesis, a heterologous system was used in which synthetic xenopus laevis c-myc transcripts, progressively deleted from their 3' end, were injected into the cytoplasm of two different host axolotl (ambystoma mexicanum) cells: stage vi oocytes and progesterone-matured oocytes (unfertilized eggs; ufe). this in vivo strategy allowed the behavior of the exogenous c-myc transcripts to be followed and differ ... | 2001 | 11284969 |
| structural and biochemical characterization of the lungfish (lepidosiren paradoxa) liver basic fatty acid binding protein. | only one fatty acid-binding protein (fabp) from the liver of the lungfish (lepidosiren paradoxa) was isolated and characterized. the sequence comparison of lungfish fabp with that of the known members of the liver fabp (l-fabp) and liver basic fabp (lb-fabp) subfamilies indicates that it is more closely related to chicken, iguana, frog, axolotl, catfish, and shark lb-fabps than to mammalian and axolotl l-fabps. lungfish liver expression of this single lb-fabp contrasts with the other fish studie ... | 2001 | 11361145 |
| expression of axolotl dazl rna, a marker of germ plasm: widespread maternal rna and onset of expression in germ cells approaching the gonad. | how germ cell specification occurs remains a fundamental question in embryogenesis. the embryos of several model organisms contain germ cell determinants (germ plasm) that segregate to germ cell precursors. in other animals, including mice, germ cells form in response to regulative mechanisms during development. to investigate germ cell determination in urodeles, where germ plasm has never been conclusively identified, we cloned a daz-like sequence from axolotls, axdazl. axdazl is homologous to ... | 2001 | 11397009 |
| conserved vertebrate chromosome segments in the large salamander genome. | urodele amphibians (salamanders) are important models for embryological, physiological, and natural history research and are also a biomedically important group because they are the only vertebrates capable of regenerating entire organ systems. to enhance the utility of salamanders for biomedical research and for understanding genome evolution, genetic linkage analysis was used to identify chromosome segments that are homologous between ambystomatid salamanders and distantly related vertebrate m ... | 2001 | 11404337 |
| amiloride blocks salt taste transduction of the glossopharyngeal nerve in metamorphosed salamanders. | studies in the last two decades have shown that amiloride-sensitive na(+) channels play a role in nacl transduction in rat taste receptors. however, this role is not readily generalized for salt taste transduction in vertebrates, because functional expression of these channels varies across species and also in development in a species. glossopharyngeal nerve responses to sodium and potassium salts were recorded in larval and metamorphosed salamanders and compared before and after the oral floor ... | 2001 | 11595673 |
| interaction of chicken liver basic fatty acid-binding protein with fatty acids: a 13c nmr and fluorescence study. | two different groups of liver fatty acid-binding proteins (l-fabps) are known: the mammalian type and the basic type. very few members of this second group of l-fabps have been characterized and studied, whereas most of the past studies were concerned with the mammalian type. the interactions of chicken liver basic fatty acid-binding protein (lb-fabp) with 1-(13)c-enriched palmitic acid (pa) and oleic acid (oa) were investigated by (13)c nmr spectroscopy. samples containing fatty acids (fa) and ... | 2001 | 11601984 |
| axbrn-1: a maternal transcript encodes a pou transcription factor that is later expressed in the developing central nervous system of axolotl embryos. | axbrn-1 encodes a class iii pou protein with a pou-specific domain and a pou homeodomain that is most similar to rhs2 from rat. in embryos axbrn-1 transcripts are maternally inherited and persist through cleavage. new transcripts accumulate beginning at the mid-blastula transition. in gastrulating embryos axbrn-1 rna is in the dorsal marginal zone and by neurula it is in the neural folds and neural plate. later, it is specific to the developing brain and anterior spinal cord. transcriptional act ... | 2001 | 11685581 |
| crystallization and preliminary x-ray study of two liver basic fatty acid-binding proteins. | the fatty acid-binding proteins (fabps) are a very well known protein family which includes the liver basic fabps (lb-fabps), a subgroup so far characterized in several vertebrates but not in mammals. the most important difference recognized between the proteins in this subgroup and the better known mammalian liver fabps (l-fabps) is the stoichiometry of ligand binding: two fatty acid molecules in l-fabps compared with one in lb-fabps. the only lb-fabp with a known three-dimensional structure is ... | 2001 | 11717512 |
| expression of fibroblast growth factors 4, 8, and 10 in limbs, flanks, and blastemas of ambystoma. | members of the fibroblast growth factor (fgf) family of molecules are critical to limb outgrowth. here, we examine the expression of fgfs in three types of limbs-embryonic (developing), mature (differentiated), and regenerating-as well as in the surrounding non-limb tissues in the mexican axolotl, ambystoma mexicanum. we have previously cloned partial cdnas of fgf4, 8, and 10 from the axolotl (christensen et al., 2001); the complete fgf10 cdna sequence is presented here. axolotl fgf10 showed ded ... | 2002 | 11836784 |
| long-term biological investigations in space. | missions in space within the next two decades will be of longer duration than those carried out up to the present time, and the effects of such long-term flights on biological organisms are unknown. results of biological experiments that have been performed to date cannot be extrapolated to results in future flights because of the unknown influence of adaptation over a long period of time. prior experiments with axolotl, fishes, and vertebrates by our research team (in part with sounding rockets ... | 1975 | 11841093 |
| cloning and modeling of cd8 beta in the amphibian ambystoma mexicanum. evolutionary conserved structures for interactions with major histocompatibility complex (mhc) class i molecules. | mammalian and avian t-cells exhibit a large number of well characterized surface molecules associated with their maturation degree. very little is known in comparison with t-cell differentiation in ectothermic vertebrates. this is mainly due to the lack of probes to identify t-cell subsets. we cloned and sequenced the first ectothermic cd8 beta dna complementary to rna from an amphibian species, the mexican axolotl. the cd8 beta chain was 30-36% identical with its avian and mammalian homologues. ... | 2002 | 12034498 |
| a novel striated tropomyosin incorporated into organized myofibrils of cardiomyocytes in cell and organ culture. | striated muscle tropomyosin is classically described as consisting of 10 exons, 1a, 2b, 3, 4, 5, 6b, 7, 8, and 9a/b, in both skeletal and cardiac muscle. a novel isoform found in embryonic axolotl heart maintains exon 9a/b of striated muscle but also has a smooth muscle exon 2a instead of exon 2b. translation and subsequent incorporation into organized myofibrils, with both isoforms, was demonstrated with green fluorescent protein fusion protein construct. mutant axolotl hearts lack sufficient t ... | 2002 | 12044866 |
| cell cycle reentry of ventricular and atrial cardiomyocytes and cells within the epicardium following amputation of the ventricular apex in the axolotl, amblystoma mexicanum: confocal microscopic immunofluorescent image analysis of bromodeoxyuridine-labeled nuclei. | to understand how to reinitiate cell division in adult human myocardium, a heart regeneration model was examined in the amphibian axolotl salamander, amblystoma mexicanum. the ventricular apex was surgically amputated and resected for 3 weeks. at 14 days of recovery, the thymidine analog 5-bromo-2'-deoxyuridine (brdu) was injected intraperitoneally to identify cell types undergoing s-phase by indirect immunofluorescence using primary anti-brdu antibodies. this is the first report showing a conce ... | 2002 | 12107494 |
| cyclopamine induces digit loss in regenerating axolotl limbs. | axolotls, with their extensive ability to regenerate as adults, provide a useful model for studying 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 gain and loss of function analyses have been limited. we demonstrated in a previous study that gain of function for secreted proteins was possible in the axolotl using the vaccinia virus to drive ... | 2002 | 12115913 |
| membranes, minerals, and proteins of developing vertebrate enamel. | developing tooth enamel is formed as organized mineral in a specialized protein matrix. in order to analyze patterns of enamel mineralization and enamel protein expression in species representative of the main extant vertebrate lineages, we investigated developing teeth in a chondrichthyan, the horn shark, a teleost, the guppy, a urodele amphibian, the mexican axolotl, an anuran amphibian, the leopard frog, two lepidosauria, a gecko and an iguana, and two mammals, a marsupial, the south american ... | 2002 | 12430167 |