Ariizumi, T., M. Kinoshita, C. Yokota, K. Takano, K. Fukuda, N. Moriyama, G.M. Malacinski, and M. Asashima (2003). Amphibian in vitro heart induction: a simple and reliable model for the study of vertebrate cardiac development. International Journal of Developmental Biology 47(6): 405-410. ISSN: 0214-6282.
Descriptors: amphibians, cardiac development, heart induction, in vitro, animal model, vertebrate, embryos, Xenopus, transplantation.
Beebee, T.J.C. (2005). Conservation genetics of amphibians. Heredity 95(6): 423-427. ISSN: 0018-067X.
Descriptors: amphibians, genetics research, conservation genetics.
Belzile, O., E. Simard, R. Gulemetova, A. Bairam, and R. Kinkead (2004). Un modele amphibien pour l'etude du developpement du controle de la respiration. [Amphibians as a model system for the investigation of respiratory control development]. Medecine Sciences MS 20(10): 904-908. ISSN: 0767-0974.
Abstract: Recent medical advances have made it possible for babies to survive premature birth at increasingly earlier developmental stages. This population requires costly and sophisticated medical care to address the problems associated with immaturity of the respiratory system. In addition to pulmonary complications, respiratory instability and apnea reflecting immaturity of the respiratory control system are major causes of hospitalization and morbidity in this highly vulnerable population. These medical concerns, combined with the curiosity of physiologists, have contributed to the expansion of research in respiratory neurobiology. While most researchers working in this field commonly use rodents as an animal model, recent research using in vitro brainstem preparation from bullfrogs (Rana catesbeiana) have revealed the technical advantages of this animal model, and shown that the basic principles underlying respiratory control and its ontogeny are very similar between these two groups of vertebrates. The present review highlights the recent advances in the area of research with a focus on intermittent (episodic) breathing and the role of serotonergic and GABAergic modulation of respiratory activity during development.
Descriptors: amphibians, bull frogs, animal model system, respiratory control system, episodicbreathing investigation, premature birth of human babies, immaturity, rodents.
Language of Text: French.
Burlibasa, L., N. Cucu, and L. Gavrila (2005). Amphibians as model organisms for studying the dynamics of eukaryote genetic material architecture. Wildlife Biology in Practice 1(1): 24-32. ISSN: print: 1646-1509; online: 1646-2742.
Descriptors: amphibia, animal model, study of dynamics of eukaryote genetic architecture, review, cytogenetics.
Endepols, H., J. Schul, H.C. Gerhardt, and W. Walkowiak (2004). 6-hydroxydopamine lesions in anuran amphibians: a new model system for Parkinson's disease? Journal of Neurobiology 60(4): 395-410. ISSN: 0022-3034.
NAL Call Number: QP351.J55
Abstract: We investigated the effects of dopamine depletion on acoustically guided behavior of anurans by conducting phonotaxis experiments with female gray treefrogs (Hyla versicolor) before and 90 min after bilateral injections of 3, 6, or 12 microg 6-hydroxydopamine (6-OHDA) into the telencephalic ventricles. In experiments with one loudspeaker playing back a standard artificial mating call, we analyzed the effects of 6-OHDA on phonotactic response time. In choice tests we measured the degree of distraction from the standard call (20 pulses/s) by three different variants with altered pulse-rate (30/s, 40/s, 60/s). Five days after experiments, brains were immunostained for tyrosine hydroxylase. Labeled neurons were counted in the suprachiasmatic nucleus, posterior tuberculum, interpeduncular nucleus, and locus coeruleus, and correlation between neuronal numbers and behavioral scores was tested. Response times increased together with 6-OHDA concentrations, which was mainly due to longer immobile periods before the animals started movement. In choice tests the most irrelevant stimulus (60/s) distracted 6-OHDA injected females from the standard stimulus, while sham injected controls were undistracted. The number of catecholaminergic neurons decreased with increasing 6-OHDA concentration in the suprachiasmatic nucleus, posterior tuberculum, and interpeduncular nucleus. The normalized number of immunoreactive neurons in the posterior tuberculum was positively correlated with phonotaxis scores in the one-speaker test, demonstrating that motor deficits are a function of tubercular cell loss. We conclude that bilateral 6-OHDA lesions in anuran amphibians cause motor (difficulty to start movements) as well as cognitive symptoms (higher distraction by irrelevant stimuli) that have also been described for human Parkinson patients.
Descriptors: anuran amphibians, gray tree frogs, new animal research model system, Parkinson's disease, 6 hydroxy dopamine lesions.
Gantress, J., G.D. Maniero, N. Cohen, and J. Robert (2003). Development and characterization of a model system to study amphibian immune responses to iridoviruses. Virology 311(2): 254-262. ISSN: 0042-6822.
Descriptors: amphibians, Xenopus laevis, model system, development, immune responses, iridoviruses, study.
Gross, M.L., W. Hanke, A. Koch, H. Ziebart, K. Amann, and E. Ritz (2002). Intraperitoneal protein injection in the axolotl: the amphibian kidney as a novel model to study tubulointerstitial activation. Kidney International 62(1): 51-59. ISSN: 0085-2538.
Descriptors: amphibians, kidney, novel model, tubulointerstitial activation, urinary system, axolotl, intraperitoneal protein injection.
Hudson, N.J. and C.E. Franklin (2002). Maintaining muscle mass during extended disuse: aestivating frogs as a model species. Journal of Experimental Biology 205(15): 2297-2303. ISSN: 0022-0949.
NAL Call Number: 442.8 B77
Descriptors: estivating frogs, model species, muscle mass, maintaining, literature review, dormancy, muscle maintenance, musculature, muscle maintenance during extended disuse, review.
Kloas, W. (2002). Amphibians as a model for the study of endocrine disruptors. In: K.W. Jeon (Editor), International Review of Cytology: A Survey of Cell Biology, Vol. 216, p. 1-57. ISBN: 978-0-12-364620-0.
Descriptors: amphibians, endocrine disrupters, study model, book chapter.
Kloas, W. and I. Lutz (2006). Amphibians as model to study endocrine disrupters. Journal of Chromatography A 1130(1, Sp. Iss. SI): 16-27. ISSN: 0021-9673.
Descriptors: amphibians, animal model, endocrine disrupters, pharmacology , endocrine system, reproductive system, bioassay, thyroid system.
Morse, R.P. and E.F. Evans (2003). The sciatic nerve of the toad Xenopus laevis as a physiological model of the human cochlear nerve. Hearing Research 182(1-2): 97-118. ISSN: 0378-5955.
Descriptors: amphibians, toad, Xenopus laevis, sciatic nerve, physiological research animal model, human cochlear nerve.
Naitoh, T., M. Yamashita, and R.J. Wassersug (2004). Life history of amphibians and gravity. Uchu Seibutsu Kagaku 18(3): 130-131. ISSN: 0914-9201.
Abstract: Anurans hold a unique position in vertebrate phylogeny, as they made the major transition from water to land. Through evolution they have acquired fundamental mechanisms to adapt to terrestrial gravity. Such mechanisms are now shared among other terrestrial vertebrates derived from ancestral amphibians. Space research, using amphibians as a model animal, is significant based on the following aspects: (1) Anuran amphibians show drastic changes in their living niche during their metamorphosis. Environments for tadpoles and for terrestrial life of frogs are quite different in terms of gravity and its associated factors. (2) Certain tadpoles, such as Rhacophorus viridis amamiensis, have a transparent abdominal wall. Thus visceral organs and their motion can be observed in these animals in non-invasive manner through their transparent abdominal skin. This feature enables biologists to evaluate the physiological state of these amphibians and study the autonomic control of visceral organs. It is also feasible for space biologists to examine how such autonomic regulation could be altered by microgravity and exposure to the space environment.
Descriptors: amphibians, physiology, anura physiology, developmental biology, gastrointestinal tract physiology, amphibia classification, amphibia growth, development, anura, classification, anura growth, development, evolution, larva growth, development, larva physiology, animal models, space flight, weightlessness.
Peinado, J.R., J.P. Castano, R. Vazquez Martinez, Y. Anouar, M.C. Tonon, H. Vaudry, F. Gracia Navarro, and M.M. Malagon (2002). Amphibian melanotrophs as a model to analyze the secretory plasticity of endocrine cells. General and Comparative Endocrinology 126(1): 4-6. ISSN: 0016-6480.
NAL Call Number: 444.8 G28
Descriptors: amphibians, pituitary gland, intermediate lobe melanotrophs, secretory plasiticity models, review.
Pierantoni, R., G. Cobellis, R. Meccariello, C. Palmiero, G. Fienga, S. Minucci, and S. Fasano (2002). The amphibian testis as model to study germ cell progression during spermatogenesis. Comparative Biochemistry and Physiology Part B Biochemistry and Molecular Biology 132(1): 131-139. ISSN: 1096-4959.
Abstract: Testicular morphology of vertebrate testis indicates requirement of local control. In urodeles, the testis is organized in lobes of increasing maturity throughout the cephalocaudal axis. The anuran testis is organized in tubules. Spermatogenesis occurs in cysts composed by Sertoli cells enveloping germ cells at synchronous stages. Moreover, in numerous species germ cell progression lasts a year which defines the sexual cycle. Due to the above quoted features, research on factors regulating germ cell progression in amphibians may reach greater insight as compared with mammalian animal models. In particular, studies on endocrine and paracrine/autocrine factors involved in the regulation of germ cell functions reveal that fos activation and a J protein, previously specifically found in mouse testis, exert an important role in spermatogonial proliferation and maturation of post-meiotic stages, respectively.
Descriptors: amphibian, testis, germ cell progression, spermatogenesis, testicular morphology, vertebrate testis.
Rollins Smith, L.A., B.D. Hopkins, and L.K. Reinert (2004). An amphibian model to test the effects of xenobiotic chemicals on development of the hematopoietic system. Environmental Toxicology and Chemistry 23(12): 2863-2867. ISSN: 0730-7268.
NAL Call Number: QH545.A1E58
Abstract: A number of manmade chemicals have deleterious effects on the developing immune system. Very few assay systems are available to study the effects of xenobiotics on hematopoietic stem cells. In rodent models, assays require exposure of pregnant females and analysis of the hematopoietic potential of stem cells from the offspring. These models are less relevant to lower vertebrates such as fish or amphibians where exposure of embryos is direct. To overcome this problem, an amphibian model was developed. Diploid (2N) embryos (16-20 h of age) of the South African clawed frog, Xenopus laevis, were exposed to 10 microg/ml diazinon or 10(-6) M lead acetate for 2 h. After 2 h, the ventral blood island (VBI) was transplanted from a chemically treated or untreated control embryo to an untreated triploid (3N) host embryo. After 55 d, the contribution of the donor VBI-derived stem cells to populations in the blood, thymus, and spleen was assessed by flow cytometry. Diazinon, but not lead acetate, interfered with the ability of transplanted stem cells to contribute to hematopoiesis. Because amphibian embryos are very sensitive indicators of the toxic effects of chemicals, this VBI assay could be employed to test any toxic chemical that is suspected of having a negative effect on development of the hematopoietic system.
Descriptors: amphibians, frog, Xenopus laevis, animal model, xenobiotic chemicals, effects, test, hematopoetic system, development, immune system, assay systems.
Ryffel, G.U. (2003). What can a frog tell us about human kidney development. Nephron 94(2): e35-e43. ISSN: 0028-2766.
Descriptors: amphibians, frog, kidney development, nephrogenesis, vertrbrates, human kidney development, renal diseases.
Schnizler, M., A. Berk, M. Fronius, and W.G. Clauss (2002). The amphibian lung provides a physiologically intact model for investigation of alveolar ion transport regulation. Pfluegers Archiv European Journal of Physiology 443(Suppl. 1): S386. ISSN: 0031-6768.
Descriptors: amphibian, lung, physiologicall intact model, alveolar ion transport, regulation, respiratory system.
Straka, H., R. Baker, and E. Gilland (2002). The frog as a unique vertebrate model for studying the rhombomeric organization of functionally identified hindbrain neurons. Brain Research Bulletin 57(3-4): 301-305. ISSN: 0361-9230.
Descriptors: frog, vertebrate model, hindbrain neurons, rhombomeric organization, studying, cranial nerve, precerebral neurons.
Tata, J.R. (2006). Amphibian metamorphosis as a model for the developmental actions of thyroid hormone. Molecular and Cellular Endocrinology 246(1-2): 10-20. ISSN: 0303-7207.
Abstract: Thyroid hormone (TH) elicits multiple physiological actions in vertebrates from fish to man. These actions can be divided into two broad categories: those where the hormone regulates developmental processes and those that involve actions in the adult organism. Amphibian metamorphosis is a most dramatic example of extensive morphological, biochemical and cellular changes occurring during post-embryonic development, which is obligatorily initiated and sustained by TH. It is, therefore, an ideal model system to understand the action of the hormone. Each tissue of the frog tadpole responds differently to TH, ranging from altered gene expression, morphogenesis, tissue re-structuring and extensive cell death, according to a developmental programme set in place before the thyroid gland begins to secrete the hormone. The key element determining the response to the hormone is the nuclear thyroid hormone receptor (TR). As in most vertebrates, there are two thyroid hormone receptors, TRalpha and TRbeta, which repress transcription in the absence of the ligand and whose concentration in the tissues is directly modulated by the hormone itself. In Xenopus, biochemical and in situ techniques have shown that the amount of TRbeta mRNA and protein are elevated 50-100 times during TH-induced metamorphic climax. This phenomenon of "autoinduction" of receptor is also seen with developmental or inductive processes regulated by other hormones acting through nuclear receptors. It is possible that receptor upregulation may be a pre-requisite for hormonal response. Recent molecular and cell biological studies have suggested that TRs function as multimeric complexes with other nuclear or chromatin proteins, such as co-repressors and co-activators, to regulate the structure of the chromatin, and thereby determine the transcription of the receptor-specified target gene. There is evidence that this may also be so for thyroid hormone regulated transcription during amphibian metamorphosis.
Descriptors: amphibia growth and development, metamorphosis biological, models biological, thyroid hormones physiology, apoptosis, receptors, thyroid hormone genetics, receptors, thyroid hormone physiology.
Yoshii, C., Y. Ueda, M. Okamoto, and M. Araki (2007). Neural retinal regeneration in the anuran amphibian Xenopus laevis post-metamorphosis: transdifferentiation of retinal pigmented epithelium regenerates the neural retina. Developmental Biology 303(1): 45-56. ISSN: 0012-1606.
Abstract: In urodele amphibians like the newt, complete retina and lens regeneration occurs throughout their lives. In contrast, anuran amphibians retain this capacity only in the larval stage and quickly lose it during metamorphosis. It is believed that they are unable to regenerate these tissues after metamorphosis. However, contrary to this generally accepted notion, here we report that both the neural retina (NR) and lens regenerate following the surgical removal of these tissues in the anuran amphibian, Xenopus laevis, even in the mature animal. The NR regenerated both from the retinal pigment epithelial (RPE) cells by transdifferentiation and from the stem cells in the ciliary marginal zone (CMZ) by differentiation. In the early stage of NR regeneration (5-10 days post operation), RPE cells appeared to delaminate from the RPE layer and adhere to the remaining retinal vascular membrane. Thereafter, they underwent transdifferentiation to regenerate the NR layer. An in vitro culture study also revealed that RPE cells differentiated into neurons and that this was accelerated by the presence of FGF-2 and IGF-1. The source of the regenerating lens appeared to be remaining lens epithelium, suggesting that this is a kind of repair process rather than regeneration. Thus, we show for the first time that anuran amphibians retain the capacity for retinal regeneration after metamorphosis, similarly to urodeles, but that the mode of regeneration differs between the two orders. Our study provides a new tool for the molecular analysis of regulatory mechanisms involved in retinal and lens regeneration by providing an alternative animal model to the newt, the only other experimental model.
Descriptors: amphibians, Xenopus laevis, neural retinal regeneration, newt, metamorphosis, retina, lens, animal model.
Zayas, J.G., D.W. O'Brien, S. Tai, J. Ding, L. Lim, and M. King (2004). Adaptation of an amphibian mucociliary clearance model to evaluate early effects of tobacco smoke exposure. Respiratory Research 5: 9. ISSN: 1465-9921.
Abstract: RATIONALE: Inhaled side-stream tobacco smoke brings in all of its harmful components impairing mechanisms that protect the airways and lungs. Chronic respiratory health consequences are a complex multi-step silent process. By the time clinical manifestations require medical attention, several structural and functional changes have already occurred. The respiratory system has to undergo an iterative process of injury, healing and remodeling with every exposure. METHODS: To have a better understanding of the initial changes that take place when first exposed to environmental tobacco smoke, we have developed an exposure model, using the frog palate that closely represents the features of obstructive airways where ciliary dysfunction and mucus hypersecretion occur. RESULTS: Mucus transport was significantly reduced, even after exposure to the smoke of one cigarette (p < 0.05) and even further with 4-cigarettes exposure (p < 0.001). Morphometric and ultrastructural studies by SEM show extensive areas of tissue disruption. Gelatinase zymography shows activation of MMP9 in mucus from palates exposed to tobacco smoke. CONCLUSIONS: The clearance of mucus on the frog palate is significantly reduced after exposure to environmental tobacco smoke. Cilia and the extracellular matrix are anatomically disrupted. Tobacco smoke triggers an increased activity of matrix metalloproteinases associated with a substantial defoliation of ciliated epithelium. These studies enhance the knowledge of the changes in the mucociliary apparatus that occur initially after exposure to environmental tobacco smoke, with the goal of understanding how these changes relate to the genesis of chronic airway pathologies in humans.
Descriptors: amphibians, frog, Rana catesbeiana, environmental exposure adverse effects, tobacco smoke exposure, animal models, mucociliary clearance, palate pathology, anatomy, histology, palate drug effects.