Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| 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 |
| lateral line placodes are induced during neurulation in the axolotl. | in order to determine the time window for induction of lateral line placodes in the axolotl, we performed two series of heterotopic and isochronic transplantations from pigmented to albino embryos at different stages of embryogenesis and assessed the distribution of pigmented neuromasts in the hosts at later stages. first, ectoderm from the prospective placodal region was transplanted to the belly between early neurula and mid tailbud stages (stages 13-27). whereas grafts from early neurulae typ ... | 2001 | 11356019 |
| 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 |
| surfactant proteins and cell markers in the respiratory epithelium of the amphibian, ambystoma mexicanum. | the respiratory tract is lined by diverse epithelial cell types whose morphology, gene expression and functions are highly specialized along the cephalo-caudal axis of the lung. pulmonary gas exchange, surface tension reduction, host defense, fluid and electrolyte transport are functions shared by various vertebrate species, each organism facing similar requirements for adaptation to air breathing. consistent with this concept, we have identified distinct respiratory epithelial cell populations ... | 2001 | 11369539 |
| 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 |
| creation of chimeric mutant axolotls: a model to study early embryonic heart development in mexican axolotls. | the mexican axolotl (ambystoma mexicanum) provides an excellent model for studying heart development since it carries a cardiac lethal mutation in gene c that results in failure of contraction of mutant embryonic myocardium. in cardiac mutant axolotls (c/c) the hearts do not beat, apparently because of an absence of organized myofibrils. to date, there has been no way to analyze the genotypes of embryos from heterozygous spawnings (+/c x +/c) until stage 35 when the normal (+/c or +/+) embryos f ... | 2001 | 11411308 |
| in vivo imaging indicates muscle fiber dedifferentiation is a major contributor to the regenerating tail blastema. | during tail regeneration in urodele amphibians such as axolotls, all of the tissue types, including muscle, dermis, spinal cord, and cartilage, are regenerated. it is not known how this diversity of cell types is reformed with such precision. in particular, the number and variety of mature cell types in the remaining stump that contribute to the blastema is unclear. using nomarski imaging, we followed the process of regeneration in the larval axolotl tail. combining this with in vivo fluorescent ... | 2001 | 11456451 |
| the eyeless mutant gene (e) in the mexican axolotl (ambystoma mexicanum) affects pax-6 expression and forebrain axonogenesis. | this study tested the hypothesis that changes in the patterns of pax-6 expression disrupt the anatomy and axonogenesis of the diencephalic areas of the eyeless axolotl. proper pax-6 expression is necessary for eye and hypothalamus morphogenesis. since the expression boundaries of pax-6 also provide a permissive environment for axonal outgrowth, an extensive study examining the effects of the eyeless gene (e) in the mexican axolotl upon pax-6 expression and forebrain axonogenesis was begun. this ... | 2001 | 11461001 |
| redneck, a new mutant of the axolotl (ambystoma mexicanum) likely affects the development of cranial neural crest. | a novel developmental mutant in the mexican axolotl is described. designated redneck (rn), the mutant gene is inherited as a simple mendelian recessive. in homozygotes, rn causes massive haemorrhage in the posterior head, rostrocaudal compression of the craniovisceral skeleton, abnormal differentiation of vertebral cartilage, micrognathia, aglossia, microphthalmia and abnormal hepatic development. affected larvae become evident at the onset of feeding, and eventually die of starvation. based on ... | 2001 | 11461006 |
| histochemical and immunohistochemical localization of neuronal nitric oxide synthase in the olfactory epithelium of the axolotl, ambystoma mexicanum. | the aim of this study was to describe the anatomic distribution of neuronal nitric oxide synthase immunoreactivity (nnos-ir) and nicotinamide-adenine dinucleotide phosphate-diaphorase (nadph-d) staining in the olfactory epithelium of the axolotl, juvenile, and neotenic adult, ambystoma mexicanum. nitric oxide (no, nitrogen monoxide) is a widespread molecule that has been identified both as a neuromodulator and as an intracellular messenger. in the olfactory system, no has been proposed to play a ... | 2001 | 11485369 |
| fibroblast growth factors in regenerating limbs of ambystoma: cloning and semi-quantitative rt-pcr expression studies. | urodele amphibians (newts and salamanders) have the ability to regenerate amputated limbs throughout their life span. because fibroblast growth factors (fgfs) play important roles in developing limbs, we initiated studies to investigate these growth factors in regenerating limbs. partial cdnas of fgf4, 8, and 10 were cloned from both the mexican axolotl, ambystoma mexicanum, and locally collected spotted salamander, ambystoma maculatum, two salamanders well recognized for their regenerative capa ... | 2001 | 11555861 |
| 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 |
| betahistine produces post-synaptic inhibition of the excitability of the primary afferent neurons in the vestibular endorgans. | betahistine has been used to treat several vestibular disorders of both central and peripheral origin. the objective of this work was to study the action of betahistine in the vestibular endorgans. experiments were done in wild larval axolotl (ambystoma tigrinum). multiunit extracellular recordings were obtained from the semicircular canal nerve using a suction electrode. betahistine (10 microm to 10 mm; n = 32) inhibited the basal spike discharge of the vestibular afferent neurons with an ic50 ... | 2001 | 11677735 |
| action mechanism of betahistine in the vestibular end organs. | betahistine has been used to treat several vestibular disorders of both central and peripheral origin. the objective of this work was to study the betahistine action mechanism at the vestibular end organs. experiments were carried out in wild larval axolotl (ambystoma tigrinum). multiunit extracellular recordings were obtained from the semicircular canal nerve using a suction electrode. betahistine (10 microm to 10 mm, n = 32) inhibited the basal spike discharge of the vestibular afferent neuron ... | 2001 | 11677837 |
| 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 |
| expression of axwnt-8 and axszl in the urodele, axolotl: comparison with xenopus. | in both the urodele axolotl and the anuran xenopus, wnt-8 is expressed in posterior lateral plate mesoderm (lpm) in neurula and tailbud stages. in contrast to xenopus, expression in axolotl is more prominent in gastrula endoderm, is not initiated in mesoderm until late gastrulation, and is present in the tailbud and in the brain at tailbud stages. sizzled is expressed in axolotl in the ventral region, similar to its pattern in xenopus. in axolotl, the wnt-8-expressing lpm remains relatively dors ... | 2001 | 11702200 |
| specification of pharyngeal endoderm is dependent on early signals from axial mesoderm. | the development of taste buds is an autonomous property of the pharyngeal endoderm, and this inherent capacity is acquired by the time gastrulation is complete. these results are surprising, given the general view that taste bud development is nerve dependent, and occurs at the end of embryogenesis. the pharyngeal endoderm sits at the dorsal lip of the blastopore at the onset of gastrulation, and because this taste bud-bearing endoderm is specified to make taste buds by the end of gastrulation, ... | 2001 | 11714682 |
| 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 |
| relationships between neuronal cell adhesion molecule and lhrh neurons in the urodele brain: a developmental immunohistochemical study. | polysialic acid (psa), a homopolymer attached to neural cell adhesion molecule (ncam) is considered a major hallmark of vertebrate cell migration. we studied the distribution of psa-ncam by immunohistochemistry, during brain development, in two urodele amphibians, pleurodeles waltl and the neotenic newt ambystoma mexicanum. in both species a gradual increase of immunolabelling was observed throughout the brain from developmental stage 30 to stage 52. at the onset of metamorphosis, some differenc ... | 2001 | 11759809 |
| 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 |
| retinoid antagonists inhibit normal patterning during limb regeneration in the axolotl, ambystoma mexicanum. | retinoic acid (ra) has been detected in the regenerating limb of the axolotl, and exogenous ra can proximalize, posteriorize, and ventralize blastemal cells. thus, ra may be an endogenous regulatory factor during limb regeneration. we have investigated whether endogenous retinoids are essential for patterning during axolotl (ambystoma mexicanum) limb regeneration by using retinoid antagonists that bind to specific rar (retinoic acid receptor) or rxr (retinoid x receptor) retinoid receptor subtyp ... | 2002 | 11857478 |
| electrorotation of axolotl embryos. | the frequency dependent dielectric properties of individual axolotl embryos (ambystoma mexicanum) were investigated experimentally utilizing the technique of electrorotation. individual axolotl embryos, immersed in low conductivity media, were subjected to a known frequency and fixed amplitude rotating ac electric field and the ensuing rotational motion of the embryo was monitored using a conventional optical microscope. none of the embryos in the pregastrulation or neurulation stages of develop ... | 2002 | 11891751 |
| characterization of a tm-4 type tropomyosin that is essential for myofibrillogenesis and contractile activity in embryonic hearts of the mexican axolotl. | a striated muscle isoform of a tropomyosin (tm-4) gene was characterized and found to be necessary for contractile function in embryonic heart. the full-length clone of this isoform was isolated from the mexican axolotl (ambystoma mexicanum) and named axolotl tropomyosin cardiac-3 (atmc-3). the gene encoded a cardiac-specific tropomyosin protein with 284 amino acid residues that demonstrated high homology to the xenopus cardiac tm-4 type tropomyosin. northern blot analysis indicates a transcript ... | 2002 | 11968015 |
| structure, diversity and expression of the tcrdelta chains in the mexican axolotl. | mammals and birds have two major populations of t cells, based on the molecular composition and biological properties of their antigen receptors (tcr). alpha beta t cells recognize antigenic peptides linked to major histocompatibility complex (mhc) molecules, and gamma delta t cells recognize native peptide or non-peptide antigens independently of mhc. very little is known about gamma delta t cells in ectothermic vertebrates. we have cloned and characterized the tcrdelta chains of an urodele amp ... | 2002 | 11981822 |
| development of larval and transformed teeth in ambystoma mexicanum (urodela, amphibia): an ultrastructural study. | odontogenesis of early larval non-pedicellate teeth, late larval teeth with a more or less distinct dividing zone and fully transformed pedicellate teeth in ambystoma mexicanum (urodela) was studied to obtain insights into the development of differently structured teeth in lower vertebrates. using transmission electron microscopy we investigated five developmental stages: (1) papilla; (2) bell stage (secretion of the matrix begins); (3) primordium (mineralization and activity of ameloblasts star ... | 2002 | 11989966 |
| 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 |
| intraperitoneal protein injection in the axolotl: the amphibian kidney as a novel model to study tubulointerstitial activation. | a substantial body of experimental evidence suggests that protein loading causes activation of proximal tubular epithelial cells with consecutive interstitial fibrosis. these studies have mostly been performed using mammalian in vivo models of glomerular damage or tissue cultures of mammalian tubulointerstitial cells. the kidney of the axolotl contains not only closed nephrons, but also nephrons with ciliated peritoneal funnels called nephrostomes that have access to the peritoneal fluid. inject ... | 2002 | 12081563 |
| 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 |
| identification and expression of helios, a member of the ikaros family, in the mexican axolotl: implications for the embryonic origin of lymphocyte progenitors. | transcription factors of the ikaros gene family are critical for the differentiation of t and b lymphocytes from pluripotent hematopoietic stem cells. to study the first steps of lymphopoiesis in the mexican axolotl, we have cloned the helios ortholog in this urodele amphibian species. we demonstrated that the axolotl helios contains a 144-bp deletion at the 5' end of the activation domain. helios is expressed in both the thymus and spleen but not in the liver of the pre-adult axolotl. during on ... | 2002 | 12115658 |
| 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 |
| urodeles remove mesoderm from the superficial layer by subduction through a bilateral primitive streak. | urodeles begin gastrulation with much of their presumptive mesoderm in the superficial cell layer, all of which must move into the deep layers during development. we studied the morphogenesis of superficial mesoderm in the urodeles ambystoma maculatum, ambystoma mexicanum, and taricha granulosa. in all three species, somitic, lateral, and ventral mesoderm move into the deep layer during gastrulation, ingressing through a "bilateral primitive streak" just inside the blastopore. the mesodermal epi ... | 2002 | 12167400 |
| regulation of lactate dehydrogenase (ldh) and alcohol dehydrogenase (adh) synthesis in liver nuclei, following their transfer into oocytes. | the regulatory effect of oocyte cytoplasm on the synthetic activity of transferred somatic cell nuclei was studied using an interspecific hybrid combination of ambystoma texanum and ambystoma mexicanum (axolotl). the enzymes lactate dehydrogenase (ldh) and alcohol dehydrogenase (adh) were used as markers of gene activity. in both species of salamanders, ldh is synthesized in the liver and oocytes, while adh is tissue-specific being synthesized in the liver but not oocytes. both ldh and adh show ... | 1976 | 12194433 |
| gallium nitrate: effects on cartilage during limb regeneration in the axolotl, ambystoma mexicanum. | gallium nitrate, a drug shown to have efficacy in paget's disease of bone, hypercalcemia of malignancy, and a variety of experimental autoimmune diseases, also inhibits the growth of some types of cancer. we examined dose and timing of administration of gallium nitrate on limb regeneration in the mexican axolotl, ambystoma mexicanum. administered by intraperitoneal injection, gallium nitrate inhibited limb regeneration in a dose-dependent manner. gallium nitrate initially suppressed epithelial w ... | 2002 | 12210121 |
| expression of hoxa5 in the heart is upregulated during thyroxin-induced metamorphosis of the mexican axolotl (ambystoma mexicanum). | widespread external and internal changes in body morphology have long been known to be hallmarks of the process of metamorphosis. however, more subtle changes, particularly at the molecular level, are only now beginning to be understood. a number of transcription factors have recently been shown to alter expression either in levels of message or in isoforms expressed. in this article, we describe a dramatic increase in the expression of the homeobox gene hoxa5 in the heart and aorta of the mexic ... | 2001 | 12213975 |
| differential post-transcriptional regulations of wnt mrnas upon axolotl meiotic maturation. | the products of the wntgene family play an essential role in several aspects of embryo patterning. we have investigated the post-transcriptional regulation of three of these genes: awnt-1, awnt-5a and awnt-5b during axolotl (ambystoma mexicanum) oogenesis, oocyte maturation and early development. we show that awnt-1, awnt-5a and awnt-5b mrnas are maternally expressed. the three transcripts are tightly regulated at specific times and display differential mrna stability, poly(a) tail length and lo ... | 2002 | 12216985 |
| different regulation of t-box genes tbx4 and tbx5 during limb development and limb regeneration. | the t-domain transcription factors tbx4 and tbx5 have been implicated, by virtue of their limb-type specific expression, in controlling the identity of vertebrate legs and arms, respectively. to study the roles of these genes in developing and regenerating limbs, we cloned tbx4 and tbx5 cdnas from the newt, and generated antisera that recognize tbx4 or tbx5 proteins. we show here that, in two urodele amphibians, newts and axolotls, the regulation of tbx4 and tbx5 differs from higher vertebrates. ... | 2002 | 12376111 |
| effects of dexamethasone treatment on iodothyronine deiodinase activities and on metamorphosis-related morphological changes in the axolotl (ambystoma mexicanum). | in amphibians, there is a close interaction between the interrenal and the thyroidal axes. hypothalamic corticotropin-releasing hormone or related peptides stimulate thyroidal activity by increasing thyrotropin synthesis and release, while corticosterone accelerates both spontaneous and thyroid hormone-induced metamorphosis. one of the mechanisms that is thought to contribute to this acceleration is a corticosterone-induced change in peripheral deiodinating activity. the present experiments were ... | 2002 | 12383443 |
| immunocytochemical localization of keratins, associated proteins and uptake of histidine in the epidermis of fish and amphibians. | keratinization and the role of histidine in some species of fish and amphibians have been analyzed by immunocytochemistry and autoradiography. in cartilaginous and bony fishes, staining of acidic (ae1-positive) and basic (ae3-positive) keratins was strong and their distribution patterns were uniform in all epidermal layers. the ae2 antibody (for keratins k1 and k10 that are typical for keratinization) did not produce any positivity. this was also observed in lungfish epidermis but the ae2 antibo ... | 2002 | 12389745 |
| amphioxus and lamprey ap-2 genes: implications for neural crest evolution and migration patterns. | the neural crest is a uniquely vertebrate cell type present in the most basal vertebrates, but not in cephalochordates. we have studied differences in regulation of the neural crest marker ap-2 across two evolutionary transitions: invertebrate to vertebrate, and agnathan to gnathostome. isolation and comparison of amphioxus, lamprey and axolotl ap-2 reveals its extensive expansion in the vertebrate dorsal neural tube and pharyngeal arches, implying co-option of ap-2 genes by neural crest cells e ... | 2002 | 12397104 |
| 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 |
| ectoderm to mesoderm lineage switching during axolotl tail regeneration. | foreign environments may induce adult stem cells to switch lineages and populate multiple tissue types, but whether this mechanism is used for tissue repair remains uncertain. urodele amphibians can regenerate fully functional, multitissue structures including the limb and tail. to determine whether lineage switching is an integral feature of this regeneration, we followed individual spinal cord cells live during tail regeneration in the axolotl. spinal cord cells frequently migrate into surroun ... | 2002 | 12471259 |
| excretory nitrogen metabolism in the juvenile axolotl ambystoma mexicanum: differences in aquatic and terrestrial environments. | the fully grown but nonmetamorphosed (juvenile) axolotl ambystoma mexicanum was ureogenic and primarily ureotelic in water. a complete ornithine-urea cycle (ouc) was present in the liver. aerial exposure impeded urea (but not ammonia) excretion, leading to a decrease in the percentage of nitrogen excreted as urea in the first 24 h. however, urea and not ammonia accumulated in the muscle, liver, and plasma during aerial exposure. by 48 h, the rate of urea excretion recovered fully, probably due t ... | 2013 | 12529847 |
| electroporation as a tool to study in vivo spinal cord regeneration. | tailed amphibians such as axolotls and newts have the unique ability to fully regenerate a functional spinal cord throughout life. where the cells come from and how they form the new structure is still poorly understood. here, we describe the development of a technique that allows the visualization of cells in the living animal during spinal cord regeneration. a microelectrode needle is inserted into the lumen of the spinal cord and short rapid pulses are applied to transfer the plasmids encodin ... | 2003 | 12557220 |
| expression of complement 3 and complement 5 in newt limb and lens regeneration. | some urodele amphibians possess the capacity to regenerate their body parts, including the limbs and the lens of the eye. the molecular pathway(s) involved in urodele regeneration are largely unknown. we have previously suggested that complement may participate in limb regeneration in axolotls. to further define its role in the regenerative process, we have examined the pattern of distribution and spatiotemporal expression of two key components, c3 and c5, during limb and lens regeneration in th ... | 2003 | 12594255 |
| extending the table of stages of normal development of the axolotl: limb development. | the existing table of stages of the normal development of the axolotl (ambystoma mexicanum) ends just after hatching. at this time, the forelimbs are small buds. in this study, we extend the staging series through completion of development of the forelimbs and hindlimbs. | 2003 | 12619140 |
| ontogeny of the vip system in the gastro-intestinal tract of the axolotl, ambystoma mexicanum: successive appearance of co-existing pacap and nos. | evidence for the presence and potential co-existence of vasoactive intestinal polypeptide (vip), pituitary adenylate cyclase-activating polypeptide (pacap) and nitric oxide synthase (nos) in gastro-intestinal endocrine cells and/or nerve fibers is conflicting and very few results exist on development. this immunofluorescence study aims to clarify the appearance and localization of vip, pacap and nos in the gastro-intestinal tract of the axolotl, ambystoma mexicanum, during ontogeny. vip-immunore ... | 2003 | 12649730 |
| surface glycoconjugates in the olfactory system of ambystoma mexicanum. | lectin binding histochemistry was performed on the olfactory system of neotenic and metamorphosed ambystoma mexicanum to investigate the distribution and density of defined carbohydrate residues on the cell surface glycoproteins of the olfactory and vomeronasal receptor cells and their terminals in the olfactory bulbs. the lectin binding patterns indicate that the main olfactory system possesses a high density of n-acetyl-galactosamine and n-acetyl-glucosamine residues, while the vomeronasal sys ... | 2003 | 12655612 |
| gonadotropin releasing hormone (gnrh) modulates odorant responses in the peripheral olfactory system of axolotls. | peripheral signal modulation plays an important role in sensory processing. activity in the vertebrate olfactory epithelium may be modulated by peptides released from the terminal nerve, such as gonadotropin releasing hormone (gnrh). here, we demonstrate that gnrh modulates odorant responses in aquatic salamanders (axolotls, ambystoma mexicanum). we recorded electrical field potentials (electro-olfactograms, or eogs) in response to stimulation with four different amino acid odorants, l-lysine, l ... | 2003 | 12672784 |
| opioid receptors mediate a postsynaptic facilitation and a presynaptic inhibition at the afferent synapse of axolotl vestibular hair cells. | this study was designed to determine the effects of opiate drugs on the electrical activity of afferent neurons and on the ionic currents of hair cells from semicircular canals. experiments were done on larval axolotls (ambystoma tigrinum). the multiunit spike activity of afferent neurons was recorded in the isolated inner ear under both resting conditions and mechanical stimulation. ionic currents were recorded using voltage clamp of hair cells isolated from the semicircular canal. in the isola ... | 2003 | 12676139 |
| 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 |
| candidate gene analysis of metamorphic timing in ambystomatid salamanders. | although much is known about the ecological significance of metamorphosis and metamorphic timing, few studies have examined the underlying genetic architecture of these traits, and no study has attempted to associate phenotypic variation to molecular variation in specific genes. here we report on a candidate gene approach (cga) to test specific loci for a statistical contribution to variation in metamorphic timing. three segregating populations (sp1, sp2 and sp3) were constructed utilizing three ... | 2003 | 12694285 |
| neural crest contributions to the lamprey head. | the neural crest is a vertebrate-specific cell population that contributes to the facial skeleton and other derivatives. we have performed focal dii injection into the cranial neural tube of the developing lamprey in order to follow the migratory pathways of discrete groups of cells from origin to destination and to compare neural crest migratory pathways in a basal vertebrate to those of gnathostomes. the results show that the general pathways of cranial neural crest migration are conserved thr ... | 2003 | 12702647 |
| 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 |
| a point mutation in bioactive rna results in the failure of mutant heart correction in mexican axolotls. | ambystoma mexicanum is an intriguing animal model for studying heart development because it carries a mutation in gene c. hearts of homozygous recessive (c/c) mutant embryos do not contain organized myofibrils and fail to beat. the defect can be corrected by organ-culturing the mutant heart in the presence of rna from anterior endoderm or endoderm/mesoderm-conditioned medium. by screening a cdna library made of total conditioned medium rna from normal axolotl embryonic endoderm, we isolated a si ... | 2003 | 12721841 |
| selective activation of thrombin is a critical determinant for vertebrate lens regeneration. | the regeneration of structures in adult animals depends on a mechanism for coupling the acute response to tissue injury or removal with the local activation of plasticity in residual differentiated cells or stem cells. many potentially relevant signals are generated after injury, and the nature of this mechanism has not been elucidated for any instance of regeneration. lens regeneration in adult vertebrates always occurs at the pupillary margin of the dorsal iris, where pigmented epithelial cell ... | 2003 | 12747839 |
| relationship between cardiac protein tyrosine phosphorylation and myofibrillogenesis during axolotl heart development. | the axolotl, ambystoma mexicanum, is a useful system for studying embryogenesis and cardiogenesis. to understand the role of protein tyrosine phosphorylation during heart development in normal and cardiac mutant axolotl embryonic hearts, we have investigated the state of protein tyrosine residues (phosphotyrosine, p-tyr) and the relationship between p-tyr and the development of organized sarcomeric myofibrils by using confocal microscopy, two-dimensional isoelectric focusing (ief)/sds-polyacryla ... | 2003 | 12747935 |
| olfactory signal modulation by molluscan cardioexcitatory tetrapeptide (fmrfamide) in axolotls (ambystoma mexicanum). | the terminal nerve, which innervates the nasal epithelia of most jawed vertebrates, is believed to release neuropeptides that modulate activity of sensory receptor neurons. the terminal nerve usually contains gonadotropin-releasing hormone as well as at least one other peptide that has not been characterized, but which bears some structural similarity to molluscan cardioexcitatory tetrapeptide (fmrfamide) and neuropeptide tyrosine (npy). we investigated the effects of fmrfamide on both voltage-g ... | 2003 | 12771020 |
| tooth development in ambystoma mexicanum: phosphatase activities, calcium accumulation and cell proliferation in the tooth-forming tissues. | prerequisites of tooth formation, cell proliferation in the tooth-forming tissues, calcium accumulation and the enzymatic activities of alkaline (alp) and acid phosphatases (acp) were investigated by immunohistochemical and histochemical methods in various developmental stages of the mexican axolotl, ambystoma mexicanum. during the growth of replacement teeth, the tooth-forming tissues continually recruit cells from the surrounding regions. the basal layer of the oral epithelium, the dental lami ... | 2003 | 12801088 |
| 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 |
| responses to amputation of denervated ambystoma limbs containing aneurogenic limb grafts. | the developing neural tubes and associated neural crest cells were removed from stage 30 ambystoma maculatum embryos to obtain larvae with aneurogenic forelimbs. forelimbs were allowed to develop to late 3 digit or early 4 digit stages. limbs amputated through the mid radius-ulna regenerated typically in the aneurogenic condition. experiments were designed to test whether grafts of aneurogenic limb tissues would rescue denervated host limb stumps into a regeneration response. in experiment 1, an ... | 2003 | 12911114 |
| [factors inhibiting development of the axial organs in axolotl in his homoplasty into the tail fin]. | 1952 | 12980029 | |
| the effect of local x-ray irradiation upon the teeth and surrounding tissues in young axolotls (siredon mexicanum). | 1952 | 12990722 | |
| [effect of roentgen irradiation of the spinal cord on regeneration of peripheral nerves in axolotls]. | 1952 | 13021020 | |
| [change of regeneration in axolotl by antithyroid substances]. | 1951 | 13029629 | |
| [action of cortisone and of acth on axolotls (amblystoma tigrinum green) as a function of the ph of the surrounding medium]. | 1952 | 13043092 | |
| [effect of fasting and of protein diet on hepatic protoplasm in axolotl]. | 1952 | 13043687 | |
| [experimental study of the function and origin of kolmer's cells of plexus chorioideus in axolotl and guinea pig]. | 1953 | 13103189 | |
| [the effect of benzopyrene on the development of triton and axolotls]. | 1953 | 13103400 | |
| [study of the action of isolated hormones and combinations of hormones on the metamorphosis of the axolotl, as a function of variation of the environment]. | 2012 | 13115785 | |
| [fine morphological and histochemical studies on the skin of axolotl]. | 1953 | 13126292 | |
| [effect of combined hormonal treatment on the metamorphosis of the axolotl; ambystoma tigrinum green; as a function of the ph of the ambient medium]. | 1953 | 13138988 | |
| [effect of hormones as a function of the ph of the environment on metamorphosis and development of the axolotl (ambystoma tigrinum green)]. | 1953 | 13142450 | |
| [effect of cortisone and acth associated with thyroxin on the metamorphosis of the axolotl with reference to the ph of environmental medium]. | 1953 | 13148679 | |
| [action of cortisone and acth on hypophysectomized axolotls (amblystoma tigrinum green) as a function of the ph of the environmental medium]. | 1953 | 13150652 | |
| a comparison of the effects of local roentgen irradiation on jaw and tooth development in young axolotls and mice. | 1954 | 13188997 | |
| [effect of thyrotropin of sturgeon on metamorphosis of axolotl]. | 1954 | 13210240 | |
| [effect of isolated hormones on the development and experimental metamorphosis of axolotls in relation to successive deficiency of the principle salts of the environment; suppression of calcium and magnesium]. | 1954 | 13219807 | |
| the influence of roentgen irradiation on the development of the eye of the axolotl. | 1955 | 13228774 | |
| the axolotl (siredon mexicanum). i. as material for scientific research. | 2006 | 13234311 | |
| [the effect of phenothiazine preparations on the regeneration process of planaria and axolotl]. | 1955 | 13262707 | |
| action of malononitrile on the embryonic development of ambystoma mexicanum and rana temporaria. | 1955 | 13267234 | |
| the axolotl (siredon mexicanum). ii. morphology and pathology. | 2006 | 13272307 | |
| [action of acth on the axolotl as a function of successive deficiency of the principle salts of the environment]. | 1955 | 13327435 | |
| investigation of the lethal effect of x-irradiation on the young axolotl (siredon mexicanum). | 1956 | 13359680 | |
| male homogamety in the mexican axolotl: a study of the progeny obtained when germ cells of a genetic male are incorporated in a developing ovary. | 1957 | 13428947 | |
| [effects of x-rays on the metachromic skin substance in the axolotl]. | 1957 | 13432196 | |
| [causes of lose of regenerative properties in the extremities of axolotl following roentgen ray irradiation]. | 1957 | 13445954 | |
| histopathology of roentgen death of young axolotl (siredon mexicanum). | 1957 | 13458572 | |
| the origin of spontaneous and experimental haploids in the mexican axolotl (siredonor ambystoma-mexicanum). | 1957 | 13475654 | |
| the developmental mechanics of pigment pattern formation in the black axolotl, amblystoma mexicanum. i. the formation of yellow and black bars in young larvae. | 1957 | 13481300 | |
| the effect of total-body x-irradiation on the adult axolotl (siredon mexicanum). | 1958 | 13506032 | |
| [autoradiography study of 14co2 incorporation in axolotl gastrulas]. | 1958 | 13539274 | |
| the effect of different doses of roentgen rays on adult axolotl (siredon mexicanum). | 1958 | 13545474 | |
| the roentgen sensitivity of various portions of the eye of young axolotl (siredon mexicanum). | 1958 | 13595168 | |
| on mast cells in the choroid plexus of the axolotl (ambystoma mex.). | 1958 | 13625921 | |
| [electron microscopic study of the fine structures of the cytoplasm of the early embryonal stages of ambystoma mexicanum]. | 1960 | 13689453 |