| sheep heart rna stimulates myofibril formation and beating in cardiac mutant axolotl hearts in organ culture. | in the mexican axolotl, ambystoma mexicanum, recessive mutant gene c, when homozygous, results in a failure of the heart to form sarcomeric myofibrils and contract normally. previous studies have shown that purified rna from normal anterior endoderm or from medium conditioned with anterior endoderm/pre-cardiac mesoderm has the capacity to rescue mutant hearts in organ culture. in the present study, rna extracted from adult sheep heart was tested for its capacity to promote differentiation in the ... | 2003 | 12684761 |
| examination of an amphibian-based assay using the larvae of xenopus laevis and ambystoma mexicanum. | semistatic acute toxicity tests of amphibian larvae (xenopus laevis and ambystoma mexicanum) were conducted at different developmental stages and by different methods to establish a simple amphibian-based assay. test substance was pentachlorophenol sodium salt (pcp-na). the endpoint was mortality and the 24-, 48-, 72-, and 96-h lc50 values were calculated by probit analysis. interspecific differences in larval responses were not clear. larval sensitivity tended to increase with larval age. newly ... | 2003 | 12706392 |
| ph modulates the vestibular afferent discharge and its response to excitatory amino acids. | in the isolated inner ear of the axolotl (ambystoma tigrinum) acid ph decreased and basic ph increased the resting and mechanically evoked spike discharge of semicircular canal afferent neurons. variations in ph also modified the afferent neuron response to n-methyl-d-aspartic acid (nmda) acid and to (+/-)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (ampa). responses to both excitatory amino acid agonists increased at ph 7.8 (41% and 22%, respectively) and decreased by perfusion of ... | 2003 | 12876466 |
| [experimental study of the function and origin of kolmer's cells of plexus chorioideus in axolotl and guinea pig]. | | 1953 | 13103189 |
| microchemical deoxyribonucleic acid determination in individual cells. | a method for the quantitative determination of dna in the 50 to 500 micromicrog. range is presented. cells or cell nuclei are isolated individually from fixed tissue by means of micromanipulation. the tissue units in question are extracted in an oil chamber with deoxyribonuclease solution. the extracts are evaporated to dryness and redissolved to lens-shaped drops, the dna contents of which are determined by a photographic-photometric procedure in ultraviolet light. determinations on calf thymoc ... | 1961 | 13725762 |
| [persistence of leptospira icterohaemorrhagiae in the axolotl (ambystoma tigrinum)]. | | 1963 | 14190217 |
| the regulation of urea-biosynthesis enzymes in vertebrates. | 1. carbamoyl phosphate synthetase, ornithine transcarbamoylase, the arginine-synthetase system and arginase were measured in the livers of ammoniotelic, ureotelic and uricotelic animals. the chelonian reptiles, whose nitrogen excretory patterns vary according to the habitat, and the mexican axolotl, a neotenic species, were also studied. 2. the levels of the activities of the first three enzymes mentioned correlate with the amount of nitrogen excreted as urea. 3. the terrestrial turtle, which ex ... | 1965 | 14343146 |
| regulative germ cell specification in axolotl embryos: a primitive trait conserved in the mammalian lineage. | how germ cells are specified in the embryos of animals has been a mystery for decades. unlike most developmental processes, which are highly conserved, embryos specify germ cells in very different ways. curiously, in mouse embryos germ cells are specified by extracellular signals; they are not autonomously specified by maternal germ cell determinants (germ plasm), as are the germ cells in most animal model systems. we have developed the axolotl (ambystoma mexicanum), a salamander, as an experime ... | 2003 | 14511484 |
| the axolotl (ambystoma mexicanum), a neotenic amphibian, expresses functional thyroid hormone receptors. | neotenic amphibians such as the axolotl (ambystoma mexicanum) are often unable to undergo metamorphosis under natural conditions. it is thought that neoteny represents a deviation from the standard course of amphibian ontogeny, affecting the thyroid axis at different levels from the central nervous system to peripheral organs. thyroid hormone receptors (trs) that bind the thyroid hormone (th) t(3) have been described in axolotl. however, the full sequences of tr were needed to better characteriz ... | 2004 | 14576183 |
| neurotrophin-independent attraction of growing sensory and motor axons towards developing xenopus limb buds in vitro. | the mechanisms for directing axons to their targets in developing limbs remain largely unknown though recent studies in mice have demonstrated the importance of neurotrophins in this process. we now report that in co-cultures of larval xenopus laevis limb buds with spinal cords and dorsal root ganglia of xenopus and axolotl (ambystoma mexicanum) axons grow directly to the limb buds over distances of up to 800 microm and in particular to sheets of epidermal cells which migrate away from the limb ... | 2004 | 14697361 |
| injection of exogenous rna in amphibian oocytes leads to rna level fluctuations which are sensitive to cordycepin, an rna chain elongation terminator. | using an in vivo heterologous system to study the stability of xenopus laevis rna injected into axolotl (ambystoma mexicanum) fertilized eggs, we have previously observed unexpected fluctuations in rna level during early development [andéol et al., differentiation 63 (1998) 69-79]. in this study, we further characterize this phenomenon and establish its existence during axolotl and xenopus oogenesis, suggesting a phylogenetically conserved mechanism. the phenomenon can occur with a variety of ex ... | 2003 | 14746268 |
| cloning and analysis of axolotl isl2 and lhx2 lim-homeodomain transcription factors. | we cloned and characterized the isl2 and lhx2 lim-homeodomain transcription factors of the mexican salamander, or axolotl, ambystoma mexicanum. using a degenerate pcr approach, partial cdnas representing five lim-homeodomain genes were cloned, indicating conservation of this class of transcription factors in urodeles. full-length cdnas for isl2 and lhx2 were identified and sequenced. the predicted isl2 and lhx2 proteins are well conserved, especially in the lim and dna-binding domains. the isl2 ... | 2004 | 15048808 |
| patterns of spatial and temporal visceral arch muscle development in the mexican axolotl (ambystoma mexicanum). | vertebrate head development is a classical topic that has received renewed attention during the last decade. most reports use one of a few model organisms (chicken, mouse, zebrafish) and have focused on molecular mechanisms and the role of the neural crest, while cranial muscle development has received less attention. here we describe cranial muscle differentiation and morphogenesis in the mexican axolotl, ambystoma mexicanum. to determine the onset of differentiation we use antibodies against d ... | 2004 | 15216519 |
| expression of a novel cardiac-specific tropomyosin isoform in humans. | tropomyosins are a family of actin binding proteins encoded by a group of highly conserved genes. humans have four tropomyosin-encoding genes: tpm1, tpm2, tpm3, and tpm4, each of which is known to generate multiple isoforms by alternative splicing, promoters, and 3' end processing. tpm1 is the most versatile and encodes a variety of tissue specific isoforms. the tpm1 isoform specific to striated muscle, designated tpm1alpha, consists of 10 exons: 1a, 2b, 3, 4, 5, 6b, 7, 8, and 9a/b. in this stud ... | 2004 | 15249230 |
| cell contact-dependent mechanisms specify taste bud pattern during a critical period early in embryonic development. | after gastrulation, the pharyngeal endoderm is specified to give rise to taste receptor organs without further signaling from other embryonic tissues. we hypothesized that intercellular signaling might be responsible for the specification of taste buds. to test if and when this signaling was occurring, intercellular contacts were transiently disrupted in cultures of pharyngeal endoderm from axolotl embryos, and the number, size, and distribution of taste buds analyzed. disruption of cell contact ... | 2004 | 15254897 |
| the scarless heart and the mrl mouse. | the ability to regenerate tissues and limbs in its most robust form is seen in many non-mammalian species. the serendipitous discovery that the mrl mouse has a profound capacity for regeneration in some ways rivalling the classic newt and axolotl species raises the possibility that humans, too, may have an innate regenerative ability. the adult mrl mouse regrows cartilage, skin, hair follicles and myocardium with near perfect fidelity and without scarring. this is seen in the ability to close th ... | 2004 | 15293806 |
| from biomedicine to natural history research: est resources for ambystomatid salamanders. | establishing genomic resources for closely related species will provide comparative insights that are crucial for understanding diversity and variability at multiple levels of biological organization. we developed ests for mexican axolotl (ambystoma mexicanum) and eastern tiger salamander (a. tigrinum tigrinum), species with deep and diverse research histories. | 2004 | 15310388 |
| gene expression in the axolotl germ line: axdazl, axvh, axoct-4, and axkit. | primordial germ cells (pgcs) in embryos of mammals and urodele amphibians are formed by induction in the absence of germ plasm. we describe expression of four germ cell-related genes through the germ cell cycle of the axolotl. the orthologs of vasa and daz-like are up-regulated in pgcs of tail bud embryos before the gonad forms and are expressed throughout the female germ cell cycle. mammalian oct-4 is a marker of pluripotency in embryonic cells. axolotl oct-4 has higher homology to oct-4 than t ... | 2004 | 15517581 |
| quantitative evaluation of morpholino-mediated protein knockdown of gfp, msx1, and pax7 during tail regeneration in ambystoma mexicanum. | vertebrate regeneration is a fascinating but poorly understood biological phenomena. urodele amphibians such as ambystoma mexicanum (the axolotl) can functionally regenerate complex body structures such as the limb and tail, including the spinal cord, throughout life. so far, molecular studies on regeneration have been limited due to the paucity of tools for knocking-down gene and protein function. in this article, we quantitatively assessed the ability of morpholinos to specifically down-regula ... | 2005 | 15580632 |
| evidence for emergence of an amphibian iridoviral disease because of human-enhanced spread. | our understanding of origins and spread of emerging infectious diseases has increased dramatically because of recent applications of phylogenetic theory. iridoviruses are emerging pathogens that cause global amphibian epizootics, including tiger salamander (ambystoma tigrinum) die-offs throughout western north america. to explain phylogeographical relationships and potential causes for emergence of western north american salamander iridovirus strains, we sequenced major capsid protein and dna me ... | 2005 | 15643965 |
| diminished myofibril organization in mutant axolotl hearts transfected with site-directed mutants of sarcomeric tropomyosins. | we used a model lacking endogenous sarcomeric tropomyosin, the cardiac mutant of the mexican axolotl, to examine the effect of mutant tropomyosins on sarcomeric myofibril formation. previous studies have introduced wild-type mouse alpha-tropomyosin into mutant hearts in organ culture with subsequent for-mation of organized myofibrils. this study examines the predominant embry-onic axolotl tpm-4 type tropomyosin (tpm4alpha), containing a conservative re- placement of glutamic acid for aspartic ac ... | 2005 | 15738587 |
| haem conformation of amphibian nytrosylhaemoglobins detected by xanes spectroscopy. | we investigated for the first time the haem stereochemistry in the nitrosylated derivative of two amphibian haemoglobins, xenopus laevis and ambystoma mexicanum, by means of x-ray absorption spectroscopy technique with the aim to explain the relationships between the active site structure and physiological function of these proteins, compared to that from humans. our results show that while the fe site local structure of human hbno is modulated by an allosteric effector such as ihp shifting the ... | 2005 | 15744461 |
| proximodistal identity during vertebrate limb regeneration is regulated by meis homeodomain proteins. | the mechanisms by which cells obtain instructions to precisely re-create the missing parts of an organ remain an unresolved question in regenerative biology. urodele limb regeneration is a powerful model in which to study these mechanisms. following limb amputation, blastema cells interpret the proximal-most positional identity in the stump to reproduce missing parts faithfully. classical experiments showed the ability of retinoic acid (ra) to proximalize blastema positional values. meis homeobo ... | 2005 | 16107473 |
| developmental and evolutionary origins of the vertebrate dentition: molecular controls for spatio-temporal organisation of tooth sites in osteichthyans. | the rainbow trout (oncorhynchus mykiss) as a developmental model surpasses both zebrafish and mouse for a more widespread distribution of teeth in the oro-pharynx as the basis for general vertebrate odontogenesis, one in which replacement is an essential requirement. studies on the rainbow trout have led to the identification of the initial sequential appearance of teeth, through differential gene expression as a changing spatio-temporal pattern, to set in place the primary teeth of the first ge ... | 2006 | 16496402 |
| crystal structure of axolotl (ambystoma mexicanum) liver bile acid-binding protein bound to cholic and oleic acid. | the family of the liver bile acid-binding proteins (l-babps), formerly called liver basic fatty acid-binding proteins (lb-fabps) shares fold and sequence similarity with the paralogous liver fatty acid-binding proteins (l-fabps) but has a different stoichiometry and specificity of ligand binding. this article describes the first x-ray structure of a member of the l-babp family, axolotl (ambystoma mexicanum) l-babp, bound to two different ligands: cholic and oleic acid. the protein binds one mole ... | 2006 | 16555310 |
| conjecture: can continuous regeneration lead to immortality? studies in the mrl mouse. | a particular mouse strain, the mrl mouse, has been shown to have unique healing properties that show normal replacement of tissue without scarring. the serendipitous discovery that the mrl mouse has a profound capacity for regeneration in some ways rivaling the classic newt and axolotl species raises the possibility that humans, too, may have an innate regenerative ability. we propose this mouse as a model for continuous regeneration with possible life-extending properties. we will use the class ... | 2006 | 16608389 |
| conserved roles for oct4 homologues in maintaining multipotency during early vertebrate development. | all vertebrate embryos have multipotent cells until gastrulation but, to date, derivation of embryonic stem (es) cell lines has been achieved only for mouse and primates. es cells are derived from mammalian inner cell mass (icm) tissue that express the class v pou domain (pouv) protein oct4. loss of oct4 in mice results in a failure to maintain icm and consequently an inability to derive es cells. here, we show that oct4 homologues also function in early amphibian development where they act as s ... | 2006 | 16651543 |
| the rise of the boy-genius: psychological neoteny, science and modern life. | the mid-20th century saw the rise of the boy-genius, probably because a personality type characterized by prolonged youthfulness is advantageous both in science and modern life generally. this is the evolution of 'psychological neoteny', in which ever-more people retain for ever-longer the characteristic behaviours and attitudes of earlier developmental stages. whereas traditional societies are characterized by initiation ceremonies marking the advent of adulthood, these have now dwindled and di ... | 2006 | 16750307 |
| rna of amvegt, the axolotl orthologue of the xenopus meso-endodermal determinant, is not localized in the oocyte. | the transcription factor, vegt, is the meso-endodermal determinant in xenopus laevis, and the localization of vegt rna to the vegetal cortex of the oocyte is an important starting point for embryonic patterning. we have cloned the vegt orthologue from the urodele amphibian, ambystoma mexicanum, the mexican axolotl. axolotl vegt (amvegt) is expressed zygotically in the presumptive mesoderm and rohon-beard neurons as in x. laevis, and its expression persists at the tip of the tail as with zebrafis ... | 2007 | 16920404 |
| early gene expression during natural spinal cord regeneration in the salamander ambystoma mexicanum. | in contrast to mammals, salamanders have a remarkable ability to regenerate their spinal cord and recover full movement and function after tail amputation. to identify genes that may be associated with this greater regenerative ability, we designed an oligonucleotide microarray and profiled early gene expression during natural spinal cord regeneration in ambystoma mexicanum. we sampled tissue at five early time points after tail amputation and identified genes that registered significant changes ... | 2007 | 17241119 |
| ranavirus-associated mass mortality in imported red tailed knobby newts (tylototriton kweichowensis): a case report. | a mass die-off of imported red tailed knobby newts (tylototriton kweichowensis) occurred in 2004 in belgium and the netherlands. in addition to massive infection with rhabdias tokyoensis, ranavirus was isolated from three dead newts examined virologically and the gene coding for the major capsid protein of the virus was sequenced. the isolate showed 99.8% similarity to the published sequence of frog virus 3. upon experimental infection of axolotls (ambystoma mexicanum) with this isolate, no mark ... | 2008 | 17449300 |
| comparative analysis of xenopus vegt, the meso-endodermal determinant, identifies an unusual conserved sequence. | the transcription factor, vegt, is the meso-endodermal determinant in xenopus laevis. we examined vegt orthologs from several anuran amphibians and the urodele amphibian, the mexican axolotl. in addition to the conserved t-box, the dna-binding domain, the orthologs share a conserved 57 amino acid domain at the c-terminal. most striking is a 17-nucleotide (nt) sequence near the 3' end of the open reading frame. the 17 nts are absolutely conserved among the anurans, whose last common ancestor live ... | 2007 | 17459091 |
| urodele p53 tolerates amino acid changes found in p53 variants linked to human cancer. | urodele amphibians like the axolotl are unique among vertebrates in their ability to regenerate and their resistance to develop cancers. it is unknown whether these traits are linked at the molecular level. | 2007 | 17903248 |
| chondrogenesis and ossification of the lissamphibian pectoral girdle. | knowledge of amphibian shoulder development is requisite for further understanding of gnathostome pectoral girdle evolution. fish and amniotes share few pectoral girdle elements, but modern amphibians exhibit a unique combination of traits that bridge the morphological gap between these two groups. i analyzed patterns of chondrogenesis, ossification, and bone histology of the pectoral girdles of two anuran species (xenopus laevis and bombina orientalis) and two urodele species (ambystoma mexican ... | 2008 | 17999401 |
| localized co-transcriptional recruitment of the multifunctional rna-binding protein celf1 by lampbrush chromosome transcription units. | the highly-extended transcription units of lampbrush chromosomes (lbcs) offer unique opportunities to study the co-transcriptional events occurring on nascent transcripts. using lbcs from amphibian oocytes, i investigated whether celf1, an rna binding protein involved in the regulation of alternative splicing, mrna stability and translation, is localized to active transcription units. antibodies raised against mammalian (cug-bp1) and amphibian (eden-bp) celf1 were used to immunostain lbc spreads ... | 2007 | 18095176 |
| effect of thyroid hormone concentration on the transcriptional response underlying induced metamorphosis in the mexican axolotl (ambystoma). | thyroid hormones (th) induce gene expression programs that orchestrate amphibian metamorphosis. in contrast to anurans, many salamanders do not undergo metamorphosis in nature. however, they can be induced to undergo metamorphosis via exposure to thyroxine (t4). we induced metamorphosis in juvenile mexican axolotls (ambystoma mexicanum) using 5 and 50 nm t4, collected epidermal tissue from the head at four time points (days 0, 2, 12, 28), and used microarray analysis to quantify mrna abundances. | 2008 | 18267027 |
| conserved pattern of otp-positive cells in the paraventricular nucleus and other hypothalamic sites of tetrapods. | the paraventricular nucleus complex (pa) is a component of central neural circuitry that regulates several homeostatic variables. the paraventricular nucleus is composed of magnocellular neurons that project to the posterior pituitary and parvicellular neurons that project to numerous sites in the central nervous system. according to the revised prosomeric model, the paraventricular nucleus is located caudal to the eye stalk along the rostrocaudal dimension of the dorsal hypothalamic alar plate. ... | 2008 | 18331876 |
| primary culture of axolotl spinal cord ependymal cells. | in order to examine the role of ependymal cells in the spinal cord regeneration of urodele amphibians, procedures were established to identify and culture these cells. cell isolation and culture conditions were determined for ependymal cells from larval and adult axolotls (ambystoma mexicanum). dissociated cells prepared from intact spinal cords were cultured on fibronectin- or laminin-coated dishes. dissociated cells attached more rapidly to fibronectin, but attached and spread on both fibronec ... | 1990 | 18620322 |
| chytridiomycosis survey in wild and captive mexican amphibians. | mexico, a rich country in terms of amphibian diversity, hosts about 375 described species. population declines have been documented for several species where it is evident that their habitat is being destroyed or modified. however, other species which inhabit pristine areas are declining as well. it has been suggested that the chytrid fungus batrachochytrium dendrobatidis (b.d.) may be one of the causes of the enigmatic declines in mexico. we surveyed a total of 45 localities, in 12 states acros ... | 2008 | 18648793 |
| oleic acid loading does not add to the nephrotoxic effect of albumin in an amphibian and chronic rat model of kidney injury. | under proteinuric conditions, ultrafiltrated albumin can induce an inflammatory and fibrotic response in proximal tubular cells. it is unclear whether albumin per se or compounds bound to albumin are nephrotoxic. some studies have supported the toxicity of albumin-bound fatty acids; however, these compared untreated, fatty acid containing, albumin and delipidated albumin. to prevent confounding by the delipidation procedure, we compared delipidated albumin and oleic acid (oa)-loaded delipidated ... | 2008 | 18653900 |
| expression cloning of tmem16a as a calcium-activated chloride channel subunit. | calcium-activated chloride channels (caccs) are major regulators of sensory transduction, epithelial secretion, and smooth muscle contraction. other crucial roles of caccs include action potential generation in characean algae and prevention of polyspermia in frog egg membrane. none of the known molecular candidates share properties characteristic of most caccs in native cells. using axolotl oocytes as an expression system, we have identified tmem16a as the xenopus oocyte cacc. the tmem16 family ... | 2008 | 18805094 |
| chytridiomycosis in an aquarium collection of frogs: diagnosis, treatment, and control. | the introduction of a new group of dendrobatid frogs to an established captive amphibian collection was followed by several acute mortalities in both resident and introduced frog populations. chytridiomycosis, caused by batrachochytrium dendrobatidis, was diagnosed by histology in two of the dead frogs. following the diagnosis, all amphibians were moved to a specially made quarantine room with strict handling protocols and treated with itraconazole. frogs, being terrestrial amphibians, were trea ... | 2008 | 18817004 |
| pitx1 expression in developing and regenerating axolotl limbs. | the expression of the homeobox transcription factor pitx1 was investigated in the mexican axolotl (ambystoma mexicanum) during limb development and regeneration by whole-mount mrna in situ hybridizations. this clone shares high amino acid identity with pitx1 from other vertebrates (92% xenopus; 87% chick; 75% human and mouse) within the region isolated. in the developing limbs, pitx1 was expressed in hindlimb mesenchyme, as has been reported in other species. the expression pattern in the hindli ... | 2008 | 18833906 |
| transcriptional response of mexican axolotls to ambystoma tigrinum virus (atv) infection. | very little is known about the immunological responses of amphibians to pathogens that are causing global population declines. we used a custom microarray gene chip to characterize gene expression responses of axolotls (ambystoma mexicanum) to an emerging viral pathogen, ambystoma tigrinum virus (atv). | 2008 | 18937860 |
| working with oocyte nuclei: cytological preparations of active chromatin and nuclear bodies from amphibian germinal vesicles. | the giant nucleus or germinal vesicle (gv) of amphibian oocytes presents a remarkable opportunity to examine nuclear structures in unprecedented levels of detail. by making use of spread preparations of gvs, it is possible to investigate the structure and function of transcription units in active chromatin and a variety of nuclear bodies, all within the limits of resolution of the light microscope. the basic method for producing gv spreads that is described here is based on simple manual dissect ... | 2008 | 18951160 |
| microarray and cdna sequence analysis of transcription during nerve-dependent limb regeneration. | microarray analysis and 454 cdna sequencing were used to investigate a centuries-old problem in regenerative biology: the basis of nerve-dependent limb regeneration in salamanders. innervated (nr) and denervated (dl) forelimbs of mexican axolotls were amputated and transcripts were sampled after 0, 5, and 14 days of regeneration. | 2009 | 19144100 |
| genic regions of a large salamander genome contain long introns and novel genes. | the basis of genome size variation remains an outstanding question because dna sequence data are lacking for organisms with large genomes. sixteen bac clones from the mexican axolotl (ambystoma mexicanum: c-value = 32 x 10(9) bp) were isolated and sequenced to characterize the structure of genic regions. | 2009 | 19144141 |
| evidence for directional selection at a novel major histocompatibility class i marker in wild common frogs (rana temporaria) exposed to a viral pathogen (ranavirus). | whilst the major histocompatibility complex (mhc) is well characterized in the anuran xenopus, this region has not previously been studied in another popular model species, the common frog (rana temporaria). nor, to date, have there been any studies of mhc in wild amphibian host-pathogen systems. we characterise an mhc class i locus in the common frog, and present primers to amplify both the whole region, and specifically the antigen binding region. as no more than two expressed haplotypes were ... | 2009 | 19240796 |
| bmp-2 functions independently of shh signaling and triggers cell condensation and apoptosis in regenerating axolotl limbs. | axolotls have the unique ability, among vertebrates, to perfectly regenerate complex body parts, such as limbs, after amputation. in addition, axolotls pattern developing and regenerating autopods from the anterior to posterior axis instead of posterior to anterior like all tetrapods studied to date. sonic hedgehog is important in establishing this anterior-posterior axis of limbs in all tetrapods including axolotls. interestingly, its expression is conserved (to the posterior side of limb buds ... | 2010 | 20152028 |
| lack of p21 expression links cell cycle control and appendage regeneration in mice. | animals capable of regenerating multiple tissue types, organs, and appendages after injury are common yet sporadic and include some sponge, hydra, planarian, and salamander (i.e., newt and axolotl) species, but notably such regenerative capacity is rare in mammals. the adult mrl mouse strain is a rare exception to the rule that mammals do not regenerate appendage tissue. certain commonalities, such as blastema formation and basement membrane breakdown at the wound site, suggest that mrl mice may ... | 2010 | 20231440 |
| a conserved mechanism for vertebrate mesoderm specification in urodele amphibians and mammals. | understanding how mesoderm is specified during development is a fundamental issue in biology, and it has been studied intensively in embryos from xenopus. the gene regulatory network (grn) for xenopus is surprisingly complex and is not conserved in vertebrates, including mammals, which have single copies of the key genes nodal and mix. why the xenopus grn should express multiple copies of nodal and mix genes is not known. to understand how these expanded gene families evolved, we investigated me ... | 2010 | 20394741 |
| functional characterization of the vertebrate primary ureter: structure and ion transport mechanisms of the pronephric duct in axolotl larvae (amphibia). | three kidney systems appear during vertebrate development: the pronephroi, mesonephroi and metanephroi. the pronephric duct is the first or primary ureter of these kidney systems. its role as a key player in the induction of nephrogenic mesenchyme is well established. here we investigate whether the duct is involved in urine modification using larvae of the freshwater amphibian ambystoma mexicanum (axolotl) as model. | 2010 | 20507566 |
| axolotl nanog activity in mouse embryonic stem cells demonstrates that ground state pluripotency is conserved from urodele amphibians to mammals. | cells in the pluripotent ground state can give rise to somatic cells and germ cells, and the acquisition of pluripotency is dependent on the expression of nanog. pluripotency is conserved in the primitive ectoderm of embryos from mammals and urodele amphibians, and here we report the isolation of a nanog ortholog from axolotls (axnanog). axnanog does not contain a tryptophan repeat domain and is expressed as a monomer in the axolotl animal cap. the monomeric form is sufficient to regulate plurip ... | 2010 | 20736286 |
| epimorphic regeneration in mice is p53-independent. | the process of regeneration is most readily studied in species of sponge, hydra, planarian and salamander (i.e., newt and axolotl). the closure of mrl mouse ear pinna through-and-through holes provides a mammalian model of unusual wound healing/regeneration in which a blastema-like structure closes the ear hole and cartilage and hair follicles are replaced. recent studies, based on a broad level of dna damage and a cell cycle pattern of g₂/m "arrest," showed that p21(cip1/waf1) was missing from ... | 2010 | 20855943 |
| electron microscopy of the amphibian model systems xenopus laevis and ambystoma mexicanum. | in this chapter we provide a set of different protocols for the ultrastructural analysis of amphibian (xenopus, axolotl) tissues, mostly of embryonic origin. for xenopus these methods include: (1) embedding gastrulae and tailbud embryos into spurr's resin for tem, (2) post-embedding labeling of methacrylate (k4m) and cryosections through adult and embryonic epithelia for correlative lm and tem, and (3) pre-embedding labeling of embryonic tissues with silver-enhanced nanogold. for the axolotl (am ... | 2010 | 20869532 |
| applying amphibian limb regeneration to human wound healing: a review. | in contrast to the limited regenerative ability found in human wound healing, which often results in unsatisfying and deficient scar formation, urodele amphibians, with the mexican axolotl as a prime example, expose an extraordinary regenerative capacity. this regeneration leads to a perfect restoration of tissue architecture, function, and aesthetics with the axolotl being actually able to reclaim complete limbs. evolutionary considerations suggest that regeneration might be a biologic principl ... | 2010 | 20948421 |
| collection of gametes from live axolotl, ambystoma mexicanum, and standardization of in vitro fertilization. | this study established the first protocol for collection of gametes from live axolotl, ambystoma mexicanum, by gentle abdominal massage and in vitro fertilization. to stimulate spermiation and ovulation, human chorionic gonadotrophin (hcg) and ovopel pellets, which are commercially used to stimulate spawning in fish, were tested. the hcg was more effective than ovopel pellets and yielded a higher semen volume in the injected males and a shorter response time in the females. collected semen by th ... | 2010 | 20965554 |
| ikaros expression in tongue sole macrophages: a marker for lipopolysaccharide- and lipoteichoic acid-induced inflammatory responses. | ikaros, an important transcription factor plays a role in the development of hemato-lymphoid system, yet its functional importance in fish macrophages remains unknown. in this study, an ikaros cdna was cloned from the half-smooth tongue sole cynoglossus semilaevis. the cdna contained an open reading frame of 1,290 nucleotides that encoded a 430 amino acid protein. the deduced protein is structurally similar to dul from other species, for example human, axolotl, and possesses 3-zinc finger and 2- ... | 2010 | 21069465 |
| severe necrotizing myocarditis caused by serratia marcescens infection in an axolotl (ambystoma mexicanum). | this report provides the first account of the pathological changes associated with infection by serratia marcescens in an adult male axolotl. the infection resulted in septicaemia with severe multifocal necrotizing myocarditis. the latter lesion evolved to cardiac rupture, haemopericardium and death resulting from cardiac tamponade. this animal was exposed to higher than usual temperatures (24-25 °c) 2 weeks before the onset of disease and this may have resulted in immunocompromise and opportuni ... | 2010 | 21168146 |
| ambloxe--an epidermal lipoxygenase of the mexican axolotl in the context of amphibian regeneration and its impact on human wound closure in vitro. | the mexican axolotl (ambystoma mexicanum) is a well-characterized example for intrinsic regeneration. as lipoxygenase signaling is of crucial importance to scarless mammalian wound healing, we postulated that lipoxygenases might be expressed during amphibian regeneration and they might also influence human cells under appropriate conditions. in this study we identified an amphibian lipoxygenase and evaluated its impact on human cells in an in vitro wound model. | 2011 | 21183847 |
| a somitic contribution to the pectoral girdle in the axolotl revealed by long-term fate mapping. | the pectoral girdle is a unique skeletal element that underwent drastic morphological changes during its evolution, especially in association with the fin-to-limb transition. comparative studies of its development are needed to gain a deeper understanding of its evolution. transplantation experiments using the quail-chick chimeric system have revealed that not only lateral plate mesoderm but also somites contribute to the pectoral girdle in birds. studies in mice and turtles also document somiti ... | 2011 | 21210942 |
| epigenetic reprogramming of breast cancer cells with oocyte extracts. | breast cancer is a disease characterised by both genetic and epigenetic alterations. epigenetic silencing of tumour suppressor genes is an early event in breast carcinogenesis and reversion of gene silencing by epigenetic reprogramming can provide clues to the mechanisms responsible for tumour initiation and progression. in this study we apply the reprogramming capacity of oocytes to cancer cells in order to study breast oncogenesis. | 2011 | 21232089 |
| differential rna-binding activity of the hnrnp g protein correlated with the sex genotype in the amphibian oocyte. | a proteomic approach has enabled the identification of an orthologue of the splicing factor hnrnp g in the amphibians xenopus tropicalis, ambystoma mexicanum, notophthalmus viridescens and pleurodeles walt, which shows a specific rna-binding affinity similar to that of the human hnrn g protein. three isoforms of this protein with a differential binding affinity for a specific rna probe were identified in the p. walt oocyte. in situ hybridization to lampbrush chromosomes of p. waltl revealed the ... | 2011 | 21278421 |
| distinct and conserved prominin-1/cd133-positive retinal cell populations identified across species. | besides being a marker of various somatic stem cells in mammals, prominin-1 (cd133) plays a role in maintaining the photoreceptor integrity since mutations in the prom1 gene are linked with retinal degeneration. in spite of that, little information is available regarding its distribution in eyes of non-mammalian vertebrates endowed with high regenerative abilities. to address this subject, prominin-1 cognates were isolated from axolotl, zebrafish and chicken, and their retinal compartmentalizati ... | 2011 | 21407811 |
| network based transcription factor analysis of regenerating axolotl limbs. | studies on amphibian limb regeneration began in the early 1700's but we still do not completely understand the cellular and molecular events of this unique process. understanding a complex biological process such as limb regeneration is more complicated than the knowledge of the individual genes or proteins involved. here we followed a systems biology approach in an effort to construct the networks and pathways of protein interactions involved in formation of the accumulation blastema in regener ... | 2011 | 21418574 |
| identification of differentially expressed thyroid hormone responsive genes from the brain of the mexican axolotl (ambystoma mexicanum). | the mexican axolotl (ambystoma mexicanum) presents an excellent model to investigate mechanisms of brain development that are conserved among vertebrates. in particular, metamorphic changes of the brain can be induced in free-living aquatic juveniles and adults by simply adding thyroid hormone (t4) to rearing water. whole brains were sampled from juvenile a. mexicanum that were exposed to 0, 8, and 18days of 50nm t4, and these were used to isolate rna and make normalized cdna libraries for 454 d ... | 2011 | 21457787 |
| origin of amphibian and avian chromosomes by fission, fusion, and retention of ancestral chromosomes. | amphibian genomes differ greatly in dna content and chromosome size, morphology, and number. investigations of this diversity are needed to identify mechanisms that have shaped the evolution of vertebrate genomes. we used comparative mapping to investigate the organization of genes in the mexican axolotl (ambystoma mexicanum), a species that presents relatively few chromosomes (n = 14) and a gigantic genome (>20 pg/n). we show extensive conservation of synteny between ambystoma, chicken, and hum ... | 2011 | 21482624 |
| the yeast two hybrid system in a screen for proteins interacting with axolotl (ambystoma mexicanum) msx1 during early limb regeneration. | urodele amphibians are exceptional in their ability to regenerate complex body structures such as limbs. limb regeneration depends on a process called dedifferentiation. under an inductive wound epidermis terminally differentiated cells transform to pluripotent progenitor cells that coordinately proliferate and eventually redifferentiate to form the new appendage. recent studies have developed molecular models integrating a set of genes that might have important functions in the control of regen ... | 2011 | 21571103 |
| absence of mutation at the 5'-upstream promoter region of the tpm4 gene from cardiac mutant axolotl (ambystoma mexicanum). | tropomyosins are a family of actin-binding proteins that show cell-specific diversity by a combination of multiple genes and alternative rna splicing. of the 4 different tropomyosin genes, tpm4 plays a pivotal role in myofibrillogenesis as well as cardiac contractility in amphibians. in this study, we amplified and sequenced the upstream regulatory region of the tpm4 gene from both normal and mutant axolotl hearts. to identify the cis-elements that are essential for the expression of the tpm4, w ... | 2011 | 21626230 |
| histology of plastic embedded amphibian embryos and larvae. | amphibians including the south african clawed frog xenopus laevis, its close relative xenopus tropicalis, and the mexican axolotl (ambystoma mexicanum) are important vertebrate models for cell biology, development, and regeneration. for the analysis of embryos and larva with altered gene expression in gain-of-function or loss-of-function studies histology is increasingly important. here, we discuss plastic or resin embedding of embryos as valuable alternatives to conventional paraffin embedding. ... | 2011 | 22083609 |
| CXCL14-like immunoreactivity in growth hormone-containing cells of urodele pituitaries. | Immunohistochemical techniques were employed to investigate the distribution of a chemokine, namely, CXCL14-like immunoreactivity in the axolotl (Ambystoma mexicanum) and Japanese black salamander (Hynobius nigrescens) pituitaries. CXCL14-immunoreactive cells concentrated at an area of the pars distalis adjacent to the pars intermedia. We found that these cells correspond to the cells immunoreactive to an antibody against rat growth hormone (GH). Immunoelectron microscopy indicated that the CXCL ... | 2011 | 22119756 |
| histological analysis of forelimb regeneration in the california newt taricha granulosa. | the regenerative ability of the forelimbs of the california rough-skinned newt, taricha granulosa was determined and compared to the same ability of the adult mexican axolotl, ambystoma mexicanum. forelimbs were amputated distally at the wrist and limbs removed at 1, 2, 3, 4, 5 and 6 weeks post-amputation were examined by histological analysis. since vitamin a and its derivatives cause extreme changes in pattern formation in the regenerating amphibian limb, we decided to study the ability of ret ... | 2005 | 1525332 |
| intracellular recordings of rod responses during dark-adaptation. | 1. dark-adaptation of rod photoreceptors has been studied in the isolated axolotl (ambystoma mexicanum) retina by intracellular recordings. rod responsiveness was greatly reduced immediately after a 30 sec partial bleach, but partially recovered with time in the dark. 2. in parallel spectrophotometric measurements using isolated retinas, regeneration of the rod pigment could not be detected after a 30 sec bleach. 3. during rod dark-adaptation, the response of a rod to a given stimulus increased ... | 2005 | 1151778 |
| immunofluorescent, immunogold, and electrophoretic studies for desmin in embryonic hearts of normal and cardiac mutant mexican axolotls, ambystoma mexicanum. | recessive mutant gene c for "cardiac nonfunction" in axolotls results in an absence of normal heart contractions in affected embryos due to a failure of myofibril formation. in the present study, the intermediate filament protein, desmin, is compared in developing normal and mutant hearts by means of two-dimensional gel electrophoresis, immunofluorescent microscopy, and immunoelectron microscopy. tissues were fixed in periodate-lysine-paraformaldehyde or paraformaldehyde-glutaraldehyde solutions ... | 2009 | 2681791 |
| [localization of glycogen in the axolotl egg before and during the first division]. | | 2016 | 5063586 |
| electrogenic glutamate uptake is a major current carrier in the membrane of axolotl retinal glial cells. | glutamate is taken up avidly by glial cells in the central nervous system. glutamate uptake may terminate the transmitter action of glutamate released from neurons, and keep extracellular glutamate at concentrations below those which are neurotoxic. we report here that glutamate evokes a large inward current in retinal glial cells which have their membrane potential and intracellular ion concentrations controlled by the whole-cell patch-clamp technique. this current seems to be due to an electro ... | 2008 | 2885752 |
| [in vitro development of blastema cells in axolotl limb regeneration: effect of insulin and nerve extracts on cellular proliferation]. | for the purpose of investigating the nature of the nervous factor which controls cell proliferation in limb blastema of newts, we have cultured primary mesenchymous cells from limb blastemas of axolotl. the cultures were carried out in petri dishes (primaria, falcon) with a basal medium with contained diluted mem supplemented with hormones (insulin, somatotropin, hydrocortisone and thyroxine). in this medium, the cells disperse from the explant from the 4th day of culture and begin to divide fro ... | 2010 | 2952210 |
| induction of spawning in the mexican axolotl (ambystoma mexicanum) by luteinizing hormone. | | 2015 | 4636361 |
| high density cell water in amphibian eggs? | the exchange of isotopic water, 2h2o and h2(18)o has been studied in amphibian eggs. the experiments were carried out with ovarian and body cavity eggs of rana temporaria and unfertilized eggs of ambystoma mexicanum. the cytoplasmic diffusion coefficient for h2(18)o was found to be 4.6 x 10(-6) cm2/s, somewhat higher than that for 2h2o, 3.4 x 10(-6) cm2/s. the total change in reduced weight, delta rw, during the isotope experiments was compared with the total amount of water in the egg cell, m. ... | 2000 | 317089 |
| three muscle fibre types in the axial muscle of axolotl (ambystoma mexicanum shaw): a quantitative light- and electron microscopic study. | morphometric analysis by light microscopy of p-phenylene-diamine stained semithin sections of axolotl tail muscle revealed differences in the cross-sectional area of the fibres and in the number of mitochondria and of lipid inclusions per fibre, and indicated the presence of three distinct types of fibres. the tripartition was found to be statistically highly significant. representative fibres from each group established by light microscopic morphometry were subjected to an ultrastructural morph ... | 1996 | 178448 |
| induced metamorphosis in ambystoma mexicanum: lack of effect of triiodothyronine on tissue or blood levels of thyrotropin-releasing hormone (trh). | | 1998 | 105962 |
| ontogeny of immunoglobulin expression in the mexican axolotl. | the ontogeny of immunoglobulin (ig) synthesis was followed at both cellular and serological levels in the mexican axolotl (ambystoma mexicanum) using polyclonal antibodies recognizing all ig molecules and a set of monoclonal antibodies (mabs) specific for the c mu and cv heavy ig chain isotypes and for the light chain constituents shared by igm and igy molecules. clusters of igm- and of igy-synthesizing lymphocytes, often located in separate sites, are first present in spleen sections of 7-week- ... | 2006 | 2698798 |
| retinoic acid coordinately proximalizes regenerate pattern and blastema differential affinity in axolotl limbs. | an assay that detects position-related differences in affinity of axolotl regeneration blastema cells in vivo was used to test whether retinoic acid, which proximalizes regenerate pattern, simultaneously proximalizes blastema cell affinity. the assay involved autografting or homografting late bud forelimb blastomas derived from the wrist, elbow or midupper arm levels to the dorsal surface of the blastema-stump junction of an ipsilateral, medium-bud-stage hindlimb regenerating from the midthigh l ... | 2011 | 3168786 |
| control of blastema cell proliferation during axolotl limb regeneration: in vitro cell culture study. | | 2012 | 3412334 |
| role of bilateral zones of ingressing superficial cells during gastrulation of ambystoma mexicanum. | vital dye staining and cell lineage tracers were used to mark superficial cells of early ambystoma mexicanum gastrulae. superficial marks placed between the equator and the blastopore, on the dorsal midline, stained notochord, whereas marks or injections made at similar animal-vegetal levels but 90 degrees to either side of the dorsal midline were later found in somitic mesoderm. notochord marks remained on the dorsal surface of the archenteron throughout gastrulation, though they became elongat ... | 2013 | 3794603 |
| the pigmentary system of developing axolotls. iv. an analysis of the axanthic phenotype. | the axanthic mutant in the mexican axolotl (ambystoma mexicanum) was analysed with respect to the differentiation of pigment cells. transmission electron micrographs revealed the presence of melanophores and cells that are described as unpigmented xanthophores in axanthic skin. iridophores apparently failed to differentiate in axanthic axolotls (a pattern similar to that observed in melanoid axolotls). chromatographic analyses of skin extracts confirmed that there are no pteridines (xanthophore ... | 2013 | 3794587 |
| changes in patterns of protein synthesis in axolotl oocytes during progesterone-induced maturation. | patterns of protein phosphorylation and synthesis during axolotl (ambystoma mexicanum) oocyte maturation were studied by incorporation of [32p]orthophosphate and [35s]methionine into polypeptides, followed by two-dimensional gel electrophoresis. various alterations were observed after progesterone treatment: de novo appearance of [35s]methionine-labelled polypeptides, a quantitative increase in previously synthesized proteins and a quantitative decrease in or disappearance of other previously sy ... | 2013 | 3723056 |
| retinoic acid modifies positional memory in the anteroposterior axis of regenerating axolotl limbs. | the effects of retinoic acid (ra) on anteroposterior (ap) positional memory of regenerating axolotl limbs were tested after removing the anterior or posterior half from the zeugopodium (lower arm or leg). ra (150 micrograms/g body wt) was injected into groups of animals bearing the following types of limbs: (1) anterior and posterior half zeugopodia grafted to the eyesocket and amputated distally 7 days later; (2) unamputated anterior and posterior half zeugopodia in situ; (3) double anterior an ... | 2014 | 3956861 |
| fine structure of the normal, transplanted and postmetamorphic pars distalis of the mexican axolotl, ambystoma mexicanum. | | 2015 | 4699358 |
| [influence of actinomycin d on metamorphosis induced by thyroxine in the axolotl]. | | 2015 | 4954055 |
| the electrical properties of the ectoderm in the amphibian embryo during induction and early development of the nervous system. | 1. the electrical properties of ectodermal cells have been studied in embryos of the axolotl ambystoma mexicanum between gastrulation and the closure of the neural tube.2. at the time of neural induction by the underlying mesoderm the mean membrane potential recorded in ectoderm cells was -30 mv (+/- 1.5 mv s.e. of mean) and in presumptive neural cells -27 mv (+/- 1.6 mv s.e. of mean).3. at late neural fold stages, when specification of the neuroectoderm is complete, the membrane potential in pr ... | 2016 | 4778140 |
| ionic mechanism for the generation of horizontal cell potentials in isolated axolotl retina. | the ionic mechanism of horizontal cell potentials was investigated in the isolated retina of the axolotl ambystoma mexicanum. the membrane potentials of both receptors and horizontal cells were recorded intracellularly while the ionic composition of the medium flowing over the receptor side of the retina was changed. the membrane potential of the horizontal cell is highly depender side of the retina was changed. the membrane potential of the horizontal cell is highly dependent on the extracellul ... | 1988 | 202664 |
| embryo surface morphology during post-gastrula development of the frog, bombina orientalis, as revealed by scanning electron microscopy. | to further study the morphology of the developing amphibian embryo, and to provide a basis for the characterization of abnormal embryogenesis, surface features of the bombina orientalis embryo during post-gastrula development were examined with the scanning electron microscope. ciliated cells similar to those reported for rama pipiens and ambystoma mexicanum were observed in the epidermis. epidermal secretory cells displaying large numbers of exocytotis apertures become prominent at the early ta ... | 1996 | 500492 |
| organization of positional information in the axolotl limb. | we have used the phenomenon of position-dependent growth stimulation, brought about by the confrontation of cells with dissimilar positional values, to reveal the organization of positional information in the center of the upper and lower arms of axolotls. when either humerus or radius was transplanted into either dorsal or posterior positions, extra growth leading to the formation of supernumerary digits occurred following amputation through the graft. however, transplants of humerus or radius ... | 2009 | 2769199 |
| the glossopharyngeal nerve of the axolotl labeled with carbocyanine dye (dii). | fluorescent carbocyanine dye (dii) was used to label the glossopharyngeal (ix) nerve in the fixed preparation of the mexican salamander, axolotl. when the cell bodies were viewed with a confocal laser scanning microscope and nomarski optics, the cytoplasm was brightly fluorescent, but not the cell nucleus. the cell bodies which send peripheral axons in the two branches of the ix nerve were mainly distributed in the rostral part of the combined glossopharyngeal-vagus ganglion, but a few cells wer ... | 1989 | 1791970 |
| the appearance of neural and glial cell markers during early development of the nervous system in the amphibian embryo. | cell-type-specific antibodies have been used to follow the appearance of neurones and glia in the developing nervous system of the amphibian embryo. differentiated neurones were recognized with antibodies against neurofilament protein while glial cells were identified with antibodies against glial fibrillary acidic protein (gfap). the appearance of neurones containing the neurotransmitters 5-hydroxytryptamine and dopamine has been charted also. in xenopus, neurofilament protein in developing neu ... | 2008 | 2627893 |
| fine structure of the epidermal leydig cells in the axolotl ambystoma mexicanum in relation to their function. | the fine structure of the leydig cells in the epidermis of the strictly aquatic adult axolotl ambystoma mexicanum resembles that of similar cells in larval salamanders. the major finding of this study is that the mucous secretion of the leydig cells is released into the intercellular spaces from which it is discharged through pores onto the surface of the epidermis where it forms a mucous layer to protect the skin. | 2009 | 2630544 |
| [prolactin enhancement of absorption of sodium ions in isolated gills from larva of ambystoma mexicanum]. | | 2014 | 4120136 |
| the first cleavage of the amphibian egg. an electron microscope study of the onset of cytokinesis in the egg of ambystoma mexicanum. | | 2016 | 4914286 |
| local embryonic matrices determine region-specific phenotypes in neural crest cells. | membrane microcarriers were used to determine the ability of regional extracellular matrices to direct neural crest cell differentiation in culture. neural crest cells from the axolotl embryo responded to extracellular matrix material explanted from the subepidermal migratory pathway by dispersing and by differentiating into pigment cells. in contrast, matrix material from the presumptive site of dorsal root ganglia stimulated pronounced cell-cell association and neurotypic expression. cell line ... | 2012 | 3388022 |