| iron is a substrate of the plasmodium falciparum chloroquine resistance transporter pfcrt in xenopus oocytes. | the chloroquine resistance transporter of the human malaria parasite plasmodium falciparum, pfcrt, is an important determinant of resistance to several quinoline and quinoline-like antimalarial drugs. pfcrt also plays an essential role in the physiology of the parasite during development inside erythrocytes. however, the function of this transporter besides its role in drug resistance is still unclear. using electrophysiological and flux experiments conducted on pfcrtexpressing xenopus laevis oo ... | 2017 | 28768767 |
| multi-omics analysis sheds light on the evolution and the intracellular lifestyle strategies of spotted fever group rickettsia spp. | arthropod-borne rickettsia species are obligate intracellular bacteria which are pathogenic for humans. within this genus, rickettsia slovaca and rickettsia conorii cause frequent and potentially severe infections, whereas rickettsia raoultii and rickettsia massiliae cause rare and milder infections. all four species belong to spotted fever group (sfg) rickettsiae. however, r. slovaca and r. raoultii cause scalp eschar and neck lymphadenopathy (senlat) and are mainly associated with dermacentor ... | 2017 | 28775717 |
| toxicity effects of functionalized quantum dots, gold and polystyrene nanoparticles on target aquatic biological models: a review. | nano-based products are widespread in several sectors, including textiles, medical-products, cosmetics, paints and plastics. nanosafety and safe-by-design are driving nanoparticle (np) production and applications through np functionalization (@nps). indeed, @nps frequently present biological effects that differ from the parent material. this paper reviews the impact of quantum dots (qds), gold nanoparticles (aunps), and polystyrene-cored nps (psnps), evidencing the role of np functionalization i ... | 2017 | 28858240 |
| effects of ginseng-spikenard heart-nourishing capsule on inactivation of c-type kv1.4 potassium channel. | this research is to explore the effects of traditional chinese medicine ginseng-spikenard heart-nourishing capsule on the inactivation of c-type kv1.4 channels (kv1.4∆n) in xenopus laevis oocytes with two-electrode voltageclamp technique. defolliculated oocytes (stage v-vi) were injected with transcribed crnas of ferret kv1.4δn channels. during recording, oocytes were continuously perfused with nd96 solution (control group) and solution prepared from ginseng-spikenard heart-nourishing capsule (e ... | 2016 | 27731805 |
| molecular evolution of two distinct dmrt1 promoters for germ and somatic cells in vertebrate gonads. | the transcription factor dmrt1 has important functions in two distinct processes, somatic-cell masculinization and germ-cell development in mammals. however, it is unknown whether the functions are conserved during evolution, and what mechanism underlies its expression in the two cell lineages. our analysis of the xenopus laevis and silurana tropicalis dmrt1 genes indicated the presence of two distinct promoters: one upstream of the noncoding first exon (ncex1), and one within the first intron. ... | 2017 | 27927791 |
| the frog inner ear: picture perfect? | many recent accounts of the frog peripheral auditory system have reproduced wever's (1973) schematic cross-section of the ear of a leopard frog. we sought to investigate to what extent this diagram is an accurate and representative depiction of the anuran inner ear, using three-dimensional reconstructions made from serial sections of rana pipiens, eleutherodactylus limbatus and xenopus laevis. in rana, three discrete contact membranes were found to separate the posterior otic (=endolymphatic) la ... | 2015 | 25630769 |
| do hormone-modulating chemicals impact on reproduction and development of wild amphibians? | globally, amphibians are undergoing a precipitous decline. at the last estimate in 2004, 32% of the approximately 6000 species were threatened with extinction and 43% were experiencing significant declines. these declines have been linked with a wide range of environmental pressures from habitat loss to climate change, disease and pollution. this review evaluates the evidence that endocrine-disrupting contaminants (edcs) - pollutants that affect hormone systems - are impacting on wild amphibians ... | 2015 | 25335651 |
| normal table of embryonic development in the four-toed salamander, hemidactylium scutatum. | we present a complete staging table of normal development for the lungless salamander, hemidactylium scutatum (caudata: plethodontidae). terrestrial egg clutches from naturally ovipositing females were collected and maintained at 15 °c in the laboratory. observations, photographs, and time-lapse movies of embryos were taken throughout the 45-day embryonic period. the complete normal table of development for h. scutatum is divided into 28 stages and extends previous analyses of h. scutatum embryo ... | 2015 | 25617760 |
| amphibase: a new genomic resource for non-model amphibian species. | more than five thousand genes annotated in the recently published xenopus laevis and xenopus tropicalis genomes do not have a candidate orthologous counterpart in other vertebrate species. to determine whether these sequences represent genuine amphibian-specific genes or annotation errors, it is necessary to analyze them alongside sequences from other amphibian species. however, due to large genome sizes and an abundance of repeat sequences, there are limited numbers of gene sequences available ... | 2017 | 28095648 |
| multicellular mathematical modelling of mesendoderm formation in amphibians. | the earliest cell fate decisions in a developing embryo are those associated with establishing the germ layers. the specification of the mesoderm and endoderm is of particular interest as the mesoderm is induced from the endoderm, potentially from an underlying bipotential group of cells, the mesendoderm. mesendoderm formation has been well studied in an amphibian model frog, xenopus laevis, and its formation is driven by a gene regulatory network (grn) induced by maternal factors deposited in t ... | 2016 | 26934886 |
| comparative analysis of cartilage marker gene expression patterns during axolotl and xenopus limb regeneration. | axolotls (ambystoma mexicanum) can completely regenerate lost limbs, whereas xenopus laevis frogs cannot. during limb regeneration, a blastema is first formed at the amputation plane. it is thought that this regeneration blastema forms a limb by mechanisms similar to those of a developing embryonic limb bud. furthermore, xenopus laevis frogs can form a blastema after amputation; however, the blastema results in a terminal cone-shaped cartilaginous structure called a "spike." the causes of this p ... | 2015 | 26186213 |
| mesodermal origin of median fin mesenchyme and tail muscle in amphibian larvae. | mesenchyme is an embryonic precursor tissue that generates a range of structures in vertebrates including cartilage, bone, muscle, kidney, and the erythropoietic system. mesenchyme originates from both mesoderm and the neural crest, an ectodermal cell population, via an epithelial to mesenchymal transition (emt). because ectodermal and mesodermal mesenchyme can form in close proximity and give rise to similar derivatives, the embryonic origin of many mesenchyme-derived tissues is still unclear. ... | 2015 | 26086331 |
| [on the classification of the cleavage patterns in amphibian embryos]. | this paper presents a brief survey and preliminary classification of embryonic cleavage patterns in the class amphibia. we use published data on 41 anuran and 22 urodele species concerning the character of the third cleavage furrow (latitudinal or longitudinal) and the stage of transition from synchronous to asynchronous blastomere divisions in the animal hemisphere (4-8-celled stage, 8-16-celled stage or later). based on this, four patterns of amphibian embryonic cleavage are recognized, and an ... | 2015 | 25720261 |
| homodimeric anoctamin-1, but not homodimeric anoctamin-6, is activated by calcium increases mediated by the p2y1 and p2x7 receptors. | the p2x7 receptor (p2x7r) is a ligand-gated ion channel that conducts na(+), k(+), and ca(2+) when activated by extracellular atp. in various cell types, such as secretory epithelia, the p2x7r is co-expressed with ca(2+)-dependent cl(-) channels of the tmem16/anoctamin family. here, we studied whether the p2x7r and tmem16a/anoctamin-1 (ano1) or tmem16f/anoctamin-6 (ano6) interact functionally and physically, using oocytes of xenopus laevis and ambystoma mexicanum (axolotl) for heterologous expre ... | 2015 | 25592660 |
| evolutionary innovation and conservation in the embryonic derivation of the vertebrate skull. | development of the vertebrate skull has been studied intensively for more than 150 years, yet many essential features remain unresolved. one such feature is the extent to which embryonic derivation of individual bones is evolutionarily conserved or labile. we perform long-term fate mapping using gfp-transgenic axolotl and xenopus laevis to document the contribution of individual cranial neural crest streams to the osteocranium in these amphibians. here we show that the axolotl pattern is strikin ... | 2014 | 25434971 |
| proteomic analysis of fibroblastema formation in regenerating hind limbs of xenopus laevis froglets and comparison to axolotl. | to gain insight into what differences might restrict the capacity for limb regeneration in xenopus froglets, we used high performance liquid chromatography (hplc)/double mass spectrometry to characterize protein expression during fibroblastema formation in the amputated froglet hindlimb, and compared the results to those obtained previously for blastema formation in the axolotl limb. | 2014 | 25063185 |
| ectopic blastema induction by nerve deviation and skin wounding: a new regeneration model in xenopus laevis. | recently, the accessory limb model (alm) has become an alternative study system for limb regeneration studies in axolotls instead of using an amputated limb. alm progresses limb regeneration study in axolotls because of its advantages. to apply and/or to compare knowledge in axolotl alm studies to other vertebrates is a conceivable next step. first, xenopus laevis, an anuran amphibian, was investigated. a xenopus frog has hypomorphic regeneration ability. its regeneration ability has been consid ... | 2014 | 27499859 |
| two different network topologies yield bistability in models of mesoderm and anterior mesendoderm specification in amphibians. | understanding the gene regulatory networks (grns) that underlie development is a major question for systems biology. the establishment of the germ layers is amongst the earliest events of development and has been characterised in numerous model systems. the establishment of the mesoderm is best characterised in the frog xenopus laevis and has been well studied both experimentally and mathematically. however, the xenopus network has significant differences from that in mouse and humans, including ... | 2014 | 24650939 |
| cranial muscle development in the model organism ambystoma mexicanum: implications for tetrapod and vertebrate comparative and evolutionary morphology and notes on ontogeny and phylogeny. | there is still confusion about the homology of several cranial muscles in salamanders with those of other vertebrates. this is true, in part, because of the fact that many muscles present in early ontogeny of amphibians disappear during development and specifically during metamorphosis. resolving this confusion is important for the understanding of the comparative and evolutionary morphology of vertebrates and tetrapods because amphibians are the phylogenetically most plesiomorphic tetrapods, co ... | 2013 | 23650269 |
| a hyperpolarization-activated ion current of amphibian oocytes. | a comparative analysis of a hyperpolarization-activated ion current present in amphibian oocytes was performed using the two-electrode voltage-clamp technique in xenopus laevis, xenopus tropicalis, and ambystoma mexicanum. this current appears to be driven mainly by cl(-) ions, is independent of ca(2+), and is made evident by applying extremely negative voltage pulses; it shows a slow activating phase and little or no desensitization. the pharmacological profile of the current is complex. the di ... | 2013 | 23440457 |
| association of modified cytosines and the methylated dna-binding protein mecp2 with distinctive structural domains of lampbrush chromatin. | we have investigated the association of dna methylation and proteins interpreting methylation state with the distinctive closed and open chromatin structural domains that are directly observable in the lampbrush chromosomes (lbcs) of amphibian oocytes. to establish the distribution in lbcs of mecp2, one of the key proteins binding 5-methylcytosine-modified dna (5mc), we expressed ha-tagged mecp2 constructs in xenopus laevis oocytes. full-length mecp2 was predominantly targeted to the closed, tra ... | 2012 | 23149574 |
| histone deacetylases are required for amphibian tail and limb regeneration but not development. | amphibians such as xenopus laevis and ambystoma mexicanum are capable of whole structure regeneration. however, transcriptional control over these events is not well understood. here, we investigate the role of histone deacetylase (hdac) enzymes in regeneration using hdac inhibitors. the class i/ii hdac inhibitor valproic acid (vpa) inhibits tail regeneration in embryos of the anuran amphibian xenopus laevis, confirming a recent report by others (tseng et al., 2011). this inhibition correlates w ... | 2015 | 22947425 |
| the extraordinary biology and development of marsupial frogs (hemiphractidae) in comparison with fish, mammals, birds, amphibians and other animals. | the study of oogenesis and early development of frogs belonging to the family hemiphractidae provide important comparison to the aquatic development of other frogs, such as xenopus laevis, because reproduction on land characterizes the hemiphractidae. in this review, the multinucleated oogenesis of the marsupial frog flectonotus pygmaeus (hemiphractidae) is analyzed and interpreted. in addition, the adaptations associated with the incubation of embryos in the pouch of the female marsupial frog g ... | 0 | 29305906 |
| comparative micrornaome analysis of the testis and ovary of the chinese giant salamander. | micrornas (mirnas) are 18-24 nucleotides non-coding rnas that regulate gene expression by post-transcriptional suppression of mrna. the chinese giant salamander (cgs, andrias davidianus), which is an endangered species, has become one of the important models of animal evolution; however, no mirna studies on this species have been conducted. in this study, two small rna libraries of cgs ovary and testis were constructed using deep sequencing technology. a bioinformatics pipeline was developed to ... | 2017 | 28630098 |
| genomic epidemiology of the emerging pathogen batrachochytrium dendrobatidis from native and invasive amphibian species in chile. | emerging fungal diseases represent a threat to food security, animal and human health worldwide. amphibian chytridiomycosis, caused by the fungus batrachochytrium dendrobatidis (bd), has been associated with catastrophic and well-documented amphibian population declines and extinctions. for the first time, bd was cultured from native and non-native wild amphibians in chile. phylogenomic analyses revealed that chilean isolates avs2, avs4 and avs7 group within the global panzootic lineage of bd (b ... | 2017 | 29205924 |
| extraordinary diversity in the origins of sex chromosomes in anurans inferred from comparative gene mapping. | sex determination in frogs (anurans) is genetic and includes both male and female heterogamety. however, the origins of the sex chromosomes and their differentiation processes are poorly known. to investigate diversity in the origins of anuran sex chromosomes, we compared the chromosomal locations of sex-linked genes in 4 species: the african clawed frog (xenopus laevis), the western clawed frog (silurana/x. tropicalis), the japanese bell-ring frog (buergeria buergeri), and the japanese wrinkled ... | 2015 | 26089094 |
| ultrastructure and motility of the spermatozoa of polypedates leucomystax (amphibia, anura, rhacophoridae). | sperm morphology is thought to be shaped by evolutionary pressure from the fertilization environment. rhacophoridae (amphibia, anura) include both foam-nesting and nonfoam-nesting species and exhibit a variety of sperm morphologies. here, we examine the sperm morphology and motility of a foam-nesting rhacophoridae frog, polypedates leucomystax. their spermatozoa have a sickle-shaped head and a thick tail containing two axonemes with their doublet microtubule ones (db1s) facing one another. these ... | 2013 | 23125050 |
| transcriptome profiles of metamorphosis in the ornamented pygmy frog microhyla fissipes clarify the functions of thyroid hormone receptors in metamorphosis. | anuran metamorphosis is an excellent system in which to study postembryonic development. studies on xenopus (mesobatrachia) show that thyroid hormone receptors (trs) regulate metamorphosis in a ligand-dependent manner by coordinating the action of hundreds of genes. however, whether this mechanism is conserved among amphibians is still unknown. to understand the molecular mechanism of this universal phenomenon, we report the transcriptional profiles of the three key developmental stages in micro ... | 2016 | 27254593 |
| expression of g proteins in the olfactory receptor neurons of the newt cynops pyrrhogaster: their unique projection into the olfactory bulbs. | we analyzed the expression of g protein α subunits and the axonal projection into the brain in the olfactory system of the semiaquatic newt cynops pyrrhogaster by immunostaining with antibodies against gαolf and gαo , by in situ hybridization using probes for gαolf , gαo , and gαi2 , and by neuronal tracing with dii and dia. the main olfactory epithelium (oe) consists of two parts, the ventral oe and dorsal oe. in the ventral oe, the gαolf - and gαo -expressing neurons are located in the apical ... | 2014 | 24771457 |
| impaired gonadal and somatic development corroborate vulnerability differences to the synthetic estrogen ethinylestradiol among deeply diverged anuran lineages. | amphibians are undergoing a global decline. one poorly investigated reason could be the pollution of aquatic habitats by endocrine disrupting compounds (edcs). we tested the susceptibility to the synthetically stabilized estrogen 17α-ethinylestradiol (ee2) in three deeply diverged anuran species, differing in sex determination systems, types of gonadogenesis and larval ecologies. to understand whether data from the amphibian model xenopus laevis (pipidae) are analogous and applicable to only dis ... | 2016 | 27434076 |
| the plasticizer bisphenol a affects somatic and sexual development, but differently in pipid, hylid and bufonid anurans. | due to their terrestrial habitats and aquatic reproduction, many amphibians are both very vulnerable and highly suitable bioindicators. the plasticizer bisphenol a (bpa) is one of the most produced chemical substances worldwide, and knowledge on its impacts on humans and animals is mounting. bpa is used for the industrial production of polycarbonate plastics and epoxy resins and found in a multitude of consumer products. studies on bpa have involved mammals, fish and the fully aquatic anuran mod ... | 2016 | 27285164 |
| sex reversal assessments reveal different vulnerability to endocrine disruption between deeply diverged anuran lineages. | multiple anthropogenic stressors cause worldwide amphibian declines. among several poorly investigated causes is global pollution of aquatic ecosystems with endocrine disrupting compounds (edcs). these substances interfere with the endocrine system and can affect the sexual development of vertebrates including amphibians. we test the susceptibility to an environmentally relevant contraceptive, the artificial estrogen 17α-ethinylestradiol (ee2), simultaneously in three deeply divergent systematic ... | 2016 | 27029458 |
| integrated assessment of biochemical markers in premetamorphic tadpoles of three amphibian species exposed to glyphosate- and methidathion-based pesticides in single and combination forms. | in this study, we evaluated the toxic effects of a glyphosate-based herbicide (gbh) and a methidathion-based insecticide (mbi), individually and in combination, on premetamorphic tadpoles of three anuran species: pelophylax ridibundus, xenopus laevis, and bufotes viridis. based on the determined 96-h lc50 values of each species, the effects of a series of sublethal concentrations of single pesticides and their mixtures after 96-h exposure and also the time-related effects of a high sublethal con ... | 2016 | 26595308 |
| comparative toxicity of methidathion and glyphosate on early life stages of three amphibian species: pelophylax ridibundus, pseudepidalea viridis, and xenopus laevis. | the assessments of pesticide toxicity on nontarget organisms have largely been focused on the determination of median lethal concentration (lc50) values using single/laboratory species. although useful, these studies cannot describe the biochemical mechanisms of toxicity and also cannot explain the effects of pesticides on natural species. in this study, the toxic effects of glyphosate and methidathion were evaluated comparatively on early developmental stages of 3 anurans-2 natural (pelophylax ... | 2013 | 23831689 |
| gastrulation and pre-gastrulation morphogenesis, inductions, and gene expression: similarities and dissimilarities between urodelean and anuran embryos. | studies of meso-endoderm and neural induction and subsequent body plan formation have been analyzed using mainly amphibians as the experimental model. xenopus is currently the predominant model, because it best enables molecular analysis of these induction processes. however, much of the embryological information on these inductions (e.g., those of the spemann-mangold organizer), and on the morphogenetic movements of inductively interacting tissues, derives from research on non-model amphibians, ... | 2012 | 22634398 |
| analysis of cell size in the gastrula of ten frog species reveals a correlation of egg with cell sizes, and a conserved pattern of small cells in the marginal zone. | we investigated the relationship between egg and cell sizes in the early gastrula of ten species of frogs with eggs of 1,100-3,500 μm diameters. we asked whether differences in cell size of the vegetal region, blastocoel roof, and marginal zone of the early gastrula were associated with egg size. alternatively, we proposed that cell size differences may associate with gastrulation characteristics. the analyzed species were as follows: xenopus laevis, engystomops randi, engystomops coloradorum, e ... | 2017 | 27381278 |
| three-dimensional reconstruction of the cranial and anterior spinal nerves in early tadpoles of xenopus laevis (pipidae, anura). | xenopus laevis is one of the most widely used model organism in neurobiology. it is therefore surprising, that no detailed and complete description of the cranial nerves exists for this species. using classical histological sectioning in combination with fluorescent whole mount antibody staining and micro-computed tomography we prepared a detailed innervation map and a freely-rotatable three-dimensional (3d) model of the cranial nerves and anterior-most spinal nerves of early x. laevis tadpoles. ... | 2017 | 29218708 |
| effects of a commonly used glyphosate-based herbicide formulation on early developmental stages of two anuran species. | environmental contamination, especially due to the increasing use of pesticides, is suggested to be one out of six main reasons for the global amphibian decline. adverse effects of glyphosate-based herbicides on amphibians have been already discussed in several studies with different conclusions, especially regarding sublethal effects at environmentally relevant concentrations. therefore, we studied the acute toxic effects (mortality, growth, and morphological changes) of the commonly used glyph ... | 2017 | 27785717 |
| the lateral line system in anuran tadpoles: neuromast morphology, arrangement, and innervation. | anuran larvae have been classified into four morphological types which reflect intraordinal macroevolution. at present, complete characterizations of the lateral line system are only available for xenopus laevis (type i) and discoglossus pictus (type iii). we analyzed the morphology, arrangement, and innervation of neuromasts related to the anterodorsal and anteroventral lateral line nerves in 10 anuran species representing types i, ii, and iv with the aim of interpreting the existing variation ... | 2014 | 24863412 |
| effects of an environmentally relevant temporal application scheme of low herbicide concentrations on larvae of two anuran species. | cultivation of herbicide-tolerant crops involves repeated applications of the complementary herbicide throughout the growing season, while in conventional corn production, herbicide application is restricted to the beginning of cultivation. repeated application of herbicides increases both the likelihood an organism will be exposed to the herbicide and the concentration it may be exposed to. we examined effects of short and pulsed exposure of the cycloxydim-based herbicide formulation focus® ult ... | 2015 | 25950411 |
| transcription factors mix1 and vegt, relocalization of vegt mrna, and conserved endoderm and dorsal specification in frogs. | protein expression of the transcription factor genes mix1 and vegt characterized the presumptive endoderm in embryos of the frogs engystomops randi, epipedobates machalilla, gastrotheca riobambae, and eleutherodactylus coqui, as in xenopus laevis embryos. protein vegt was detected in the animal hemisphere of the early blastula in all frogs, and only the animal pole was vegt-negative. this finding stimulated a vegt mrna analysis in x. laevis eggs and embryos. vegt mrna was detected in the animal ... | 2016 | 27140624 |
| frogs as integrative models for understanding digestive organ development and evolution. | the digestive system comprises numerous cells, tissues and organs that are essential for the proper assimilation of nutrients and energy. many aspects of digestive organ function are highly conserved among vertebrates, yet the final anatomical configuration of the gut varies widely between species, especially those with different diets. improved understanding of the complex molecular and cellular events that orchestrate digestive organ development is pertinent to many areas of biology and medici ... | 2016 | 26851628 |
| cranial muscle development in frogs with different developmental modes: direct development versus biphasic development. | normal development in anurans includes a free swimming larva that goes through metamorphosis to develop into the adult frog. we have investigated cranial muscle development and adult cranial muscle morphology in three different anuran species. xenopus laevis is obligate aquatic throughout lifetime, rana(lithobates) pipiens has an aquatic larvae and a terrestrial adult form, and eleutherodactylus coqui has direct developing juveniles that hatch from eggs deposited on leaves (terrestrial). the adu ... | 2014 | 24877162 |
| commitment to nutritional endoderm in eleutherodactylus coqui involves altered nodal signaling and global transcriptional repression. | the vegetal cells of a xenopus laevis embryo commit to mesendoderm via the nodal-signaling pathway. in the direct developing frog eleutherodactylus coqui, mesendoderm is specified at the marginal zone of the early gastrula, and vegetal core cells transform into nutritional endoderm. nutritional endoderm, a novel tissue, consists of transient, yolky cells that provide nutrition but remain undifferentiated. we report a dual regulation for the generation of nutritional endoderm. first, differential ... | 2014 | 24323742 |
| characterization of the nutritional endoderm in the direct developing frog eleutherodactylus coqui. | unlike xenopus laevis, eleutherodactylus coqui develops without a tadpole. the yolk-rich vegetal region of the embryo forms a transient nutritive tissue, the nutritional endoderm (ne). the definitive endoderm (de) in e. coqui comes from cells closer to the animal pole in contrast to its vegetal origin in x. laevis. rna important for initiating the endoderm specification network is absent in presumptive ne cells, raising the question whether signaling occurs in them. we explored the nature of ne ... | 2013 | 24043604 |
| expression of cyclin d1, cyclin d2, and n-myc in embryos of the direct developing frog eleutherodactylus coqui, with a focus on limbs. | species of frogs that develop directly have removed the tadpole from their ontogeny and form adult structures precociously. to see whether cell cycle regulators could be involved in this altered embryogenesis, we examined the expression of ccnd1, ccnd2, and mycn in embryos of the direct developing frog, eleutherodactylus coqui. notable differences compared to embryos of xenopus laevis, a species with a tadpole, included prominent expression of ccnd2 in the midbrain and ccnd1 in the mandibular ne ... | 2017 | 23473789 |
| metamorphosis in a frog that does not have a tadpole. | the evolutionary removal of the tadpole from the frog life history is a very successful strategy, particularly in the tropics. these direct developers form limbs and a frog-like head early in embryogenesis, and they have reduced or lost tadpole-specific structures, like gills, a long, coiled intestine, and tadpole teeth and jaws. despite the apparently continuous development to the frog morphology, the direct developer, eleutherodactylus coqui, undergoes a cryptic metamorphosis requiring thyroid ... | 2013 | 23347522 |
| expression of a cardiac myosin gene in non-heart tissues of developing frogs. | direct developing frogs, like eleutherodactylus coqui, provide opportunities to investigate limb early development in anuran amphibians that are less available in species with tadpoles. we have found that myosin heavy chain 6 (myh6), a myosin gene usually considered heart-specific in xenopus and other animals, is expressed in limbs of e. coqui embryos. the gene for microrna(mir)-208 is contained in an intron of the e. coqui myh6 gene as in mammals, and mir -208 was detected as a microrna, more h ... | 2013 | 23076351 |
| variation in the schedules of somite and neural development in frogs. | the timing of notochord, somite, and neural development was analyzed in the embryos of six different frog species, which have been divided into two groups, according to their developmental speed. rapid developing species investigated were xenopus laevis (pipidae), engystomops coloradorum, and engystomops randi (leiuperidae). the slow developers were epipedobates machalilla and epipedobates tricolor (dendrobatidae) and gastrotheca riobambae (hemiphractidae). blastopore closure, notochord formatio ... | 2012 | 23184997 |
| expression of the aquaglyceroporin hc-9 in a freeze-tolerant amphibian that accumulates glycerol seasonally. | as ambient temperatures fall in the autumn, freeze-tolerant cope's gray treefrogs, dryophytes chrysoscelis (formerly hyla chrysoscelis), accumulate glycerol as a cryoprotective agent. we hypothesized that these treefrogs express an ortholog of the mammalian aquaglyceroporin aqp9 and that aqp9 expression is upregulated in the cold to facilitate glycerol transport. we sequenced 1790 bp from cloned cdna that codes for a 315 amino acid protein, hc-9, containing the predicted six transmembrane spanni ... | 2017 | 28784850 |
| gene expression profiles in rana pirica tadpoles following exposure to a predation threat. | rana pirica tadpoles show morphological changes in response to a predation threat: larvae of the dragonfly aeshna nigroflava induce heightened tail depth, whereas larval salamander hynobius retardatus induce a bulgy morphology with heightened tail depth. although both predators induce similar tail morphologies, it is possible that there are functional differences between these tail morphs. | 2015 | 25886855 |
| passive stiffness of hindlimb muscles in anurans with distinct locomotor specializations. | anurans (frogs and toads) have been shown to have relatively compliant skeletal muscles. using a meta-analysis of published data we have found that muscle stiffness is negatively correlated with joint range of motion when examined across mammalian, anuran and bird species. given this trend across a broad phylogenetic sample, we examined whether the relationship held true within anurans. we identified four species that differ in preferred locomotor mode and hence joint range of motion (lithobates ... | 2015 | 26006308 |
| transcriptomic and macroevolutionary evidence for phenotypic uncoupling between frog life history phases. | anuran amphibians undergo major morphological transitions during development, but the contribution of their markedly different life-history phases to macroevolution has rarely been analysed. here we generate testable predictions for coupling versus uncoupling of phenotypic evolution of tadpole and adult life-history phases, and for the underlying expression of genes related to morphological feature formation. we test these predictions by combining evidence from gene expression in two distantly r ... | 2017 | 28504275 |
| alterations in ambient salinity and ph lead to modulation of developmental gene expression in microhyla ornata (duméril and bibron) and xenopus laevis (daudin). | naturally fertilized microhyla ornata and xenopus laevis embryos at dorsal lip of blastopore stage were exposed to 0.3, and 0.6% sodium chloride for high salinity treatment and dilute hydrochloric acid and sodium hydroxide for treatment with low and high ph, respectively. after treatment for different durations, embryos were studied morphologically and using in situ hybridization with selected genes important for normal development and for coping with environmental stress. altered salinity and p ... | 2012 | 23016490 |
| genetic and genomic interactions of animals with different ploidy levels. | polyploid animals have independently evolved from diploids in diverse taxa across the tree of life. we review a few polyploid animal species or biotypes where recently developed molecular and cytogenetic methods have significantly improved our understanding of their genetics, reproduction and evolution. mitochondrial sequences that target the maternal ancestor of a polyploid show that polyploids may have single (e.g. unisexual salamanders in the genus ambystoma) or multiple (e.g. parthenogenetic ... | 2013 | 23751376 |
| patterns of protein synthesis in oocytes and early embryos of rana esculenta complex. | we have used isotopic labelling and both one-and two-dimensional electrophoretic procedures to analyse the protien synthesis patterns in oocytes and early embryos of three phenotypes of the european green frogs. the results demonstrated that protein patterns of rana ridibunda and r. esculenta are identical, but that they differ from those of r. lessonae. progeny of the lethal cross r. esculenta × r. esculenta showed a distinct delay in the appearance of stage-specific proteins during early embry ... | 1986 | 28305271 |
| a screening assay for thyroid hormone signaling disruption based on thyroid hormone-response gene expression analysis in the frog pelophylax nigromaculatus. | amphibian metamorphosis provides a wonderful model to study the thyroid hormone (th) signaling disrupting activity of environmental chemicals, with xenopus laevis as the most commonly used species. this study aimed to establish a rapid and sensitive screening assay based on th-response gene expression analysis using pelophylax nigromaculatus, a native frog species distributed widely in east asia, especially in china. to achieve this, five candidate th-response genes that were sensitive to t3 ind ... | 2015 | 26257357 |
| molecular characterization and mrna expression of ribosomal protein l8 in rana nigromaculata during development and under exposure to hormones. | like xenopus laevis, some species of the rana genus are also used to study endocrine disrupting chemicals (edcs). although ribosomal protein l8 (rpl8) is the most-used reference gene for analyzing gene expression by quantitative reverse transcription polymerase chain reaction in rana, its suitability as the reference gene has never been validated in any species of the rana genus. we characterized rpl8 cdna in rana nigromaculata, a promising native species in east asia for assaying endocrine disr ... | 2014 | 25458689 |
| molecular characterization and developmental expression patterns of thyroid hormone receptors (trs) and their responsiveness to tr agonist and antagonist in rana nigromaculata. | considering some advantages of rana nigromaculata as an experimental species, we propose that this species, like xenopus laevis, could be used to assay thyroid hormone (th) signaling disrupting actions. to validate the utilizability of r. nigromaculata, we investigated the responsiveness of r. nigromaculata to a th receptor (tr) agonist (t3) and antagonist (amiodarone) by analyzing expression, based on characterizing tr cdna and developmental expression patterns. with high levels of identity wit ... | 2014 | 25288553 |
| application of local gene induction by infrared laser-mediated microscope and temperature stimulator to amphibian regeneration study. | urodele amphibians (newts and salamanders) and anuran amphibians (frogs) are excellent research models to reveal mechanisms of three-dimensional organ regeneration since they have exceptionally high regenerative capacity among tetrapods. however, the difficulty in manipulating gene expression in cells in a spatially restricted manner has so far hindered elucidation of the molecular mechanisms of organ regeneration in amphibians. recently, local heat shock by laser irradiation has enabled local g ... | 2015 | 26510480 |
| toxicity of ceo2 nanoparticles at different trophic levels--effects on diatoms, chironomids and amphibians. | the aim of the present work is to provide wider information on the toxicity of cerium dioxide nanoparticles (ceo2 nps) in aquatic environments, by studying the toxicity of two types of ceo2 nps for four species (diatoms nitzschia palea, the sediment-dwelling invertebrate chironomus riparius, and the amphibian larvae xenopus laevis and pleurodeles waltl.). the two types of ceo2 nps have different intrinsic properties: some of them are small citrate-coated spheres (2-5 nm), and the others are larg ... | 2015 | 25086917 |
| the sensitivity of an immature vestibular system to altered gravity. | stimulus deprivation or stimulus augmentation can induce long-lasting modifications to sensory and motor systems. if deprivation is effective only during a limited period of life this phase is called "critical period." a critical period was described for the development of the roll-induced vestibuloocular reflex (rvor) of xenopus laevis using spaceflights. spaceflight durations and basic conditions of xenopus' development did not make it possible to answer the question whether exposure of the im ... | 2012 | 22570271 |
| triclosan exposure alters postembryonic development in a pacific tree frog (pseudacris regilla) amphibian metamorphosis assay (treema). | the amphibian metamorphosis assay (ama), developed for xenopus laevis, is designed to identify chemicals that disrupt thyroid hormone (th)-mediated biological processes. we adapted the ama for use on an ecologically-relevant north american species, the pacific tree frog (pseudacris regilla), and applied molecular endpoints to evaluate the effects of the antibacterial agent, triclosan (tcs). premetamorphic (gosner stage 26-28) tadpoles were immersed for 21 days in solvent control, 1.5 μg/l thyrox ... | 2013 | 23159728 |
| effects of ammonium nitrate, sodium nitrate, and urea on red-legged frogs, pacific treefrogs, and african clawed frogs. | | 1999 | 10475914 |
| vitamin a induced homeotic hindlimb formation on dorsal and ventral sides of regenerating tissue of amputated tails of japanese brown frog tadpoles. | when anuran tadpoles are treated with vitamin a after tail amputation, hindlimb-like structures can be generated instead of the lost tail part at the amputation site. this homeotic transformation was initially expected to be a key to understanding the body plan of vertebrates. unfortunately, homeotic limb formation has been reproduced in only some indian frog species and a european species, but not in experimental anurans such as xenopus laevis or rana catesbeiana. consequently, this fascinating ... | 2017 | 29094344 |
| variability of rheotaxis behaviors in larval bullfrogs highlights species diversity in lateral line function. | the morphology and distribution of lateral line neuromasts vary between ecomorphological types of anuran tadpoles, but little is known about how this structural variability contributes to differences in lateral-line mediated behaviors. previous research identified distinct differences in one such behavior, positive rheotaxis towards the source of a flow, in two tadpole species, the african clawed frog (xenopus laevis; type 1) and the american bullfrog (rana catesbeiana; type 4). because these tw ... | 2016 | 27870909 |
| comparative study of diclofenac-induced embryotoxicity and teratogenesis in xenopus laevis and lithobates catesbeianus, using the frog embryo teratogenesis assay: xenopus (fetax). | water is an increasingly deteriorated, limited natural resource due to population increase and industrialization. also, the widespread use of pharmaceuticals in modern society leads to their presence in domestic, hospital and industrial effluents. due to their analgesic properties, some of the most commonly used pharmaceuticals are nonsteroidal anti-inflammatory drugs (nsaids). high concentrations of one these products, diclofenac (dcf), have been detected in effluents and water bodies of differ ... | 2017 | 27644024 |
| quantification of 11 thyroid hormones and associated metabolites in blood using isotope-dilution liquid chromatography tandem mass spectrometry. | this paper describes a novel analytical methodology for the simultaneous determination of absolute and total concentrations of 11 native thyroid hormones and associated metabolites, viz. thyroxine (t4), 3,3', 5-triiodothyronine (t3), 3,3', 5'-triiodothyronine (rt3), 3,5-diiodothyronine (3,5-t2), 3,3'- diiodothyronine (3,3'-t2), 3-iodothyronine (t1), thyronine (t0), 3-iodothyronamine (t1am), tetraiodothyroacetic acid (tetrac), triiodothyroacetic acid (triac), and diiodothyroacetic acid (diac), in ... | 2016 | 27215639 |
| de novo transcriptome assemblies of rana (lithobates) catesbeiana and xenopus laevis tadpole livers for comparative genomics without reference genomes. | in this work we studied the liver transcriptomes of two frog species, the american bullfrog (rana (lithobates) catesbeiana) and the african clawed frog (xenopus laevis). we used high throughput rna sequencing (rna-seq) data to assemble and annotate these transcriptomes, and compared how their baseline expression profiles change when tadpoles of the two species are exposed to thyroid hormone. we generated more than 1.5 billion rna-seq reads in total for the two species under two conditions as tre ... | 2015 | 26121473 |
| purification and characterization of cholecystokinin from the skin of salamander tylototriton verrucosus. | as a group of intestinal hormones and neurotransmitters, cholecystokinins (ccks) regulate and affect pancreatic enzyme secretion, gastrointestinal motility, pain hypersensitivity, digestion and satiety, and generally contain a dymgwmdfg sequence at the c-terminus. many ccks have been reported in mammals. however, only a few have been reported in amphibians, such as hyla nigrovittata, xenopus laevis, and rana catesbeiana, with none reported in urodele amphibians like newts and salamanders. here, ... | 2015 | 26018861 |
| reprint of "baroreflex function in anurans from different environments". | anurans from terrestrial environments have an enhanced ability to maintain mean arterial blood pressure (pm) through lymph mobilization in response to desiccation or hemorrhage compared with semiaquatic or aquatic species. because short term blood pressure homeostasis is regulated by arterial baroreceptors, we compared baroreflex function in three species of anurans that span a range of environments, dehydration tolerance and an ability to maintain pm with dehydration and hemorrhage. the cardiac ... | 2015 | 25843212 |
| the effect of long-term corticosterone treatment on blood cell differentials and function in laboratory and wild-caught amphibian models. | the effect of long-term stress on amphibian immunity is not well understood. we modeled a long-term endocrine stress scenario by elevating plasma corticosterone in two species of amphibians and examined effects on white blood cell differentials and innate immune activity. plasma corticosterone was elevated in american bullfrogs (lithobates catesbeianus) by surgically implanting corticosterone capsules and in african clawed frogs (xenopus laevis) by immersion in corticosterone-treated water. to p ... | 2015 | 25616196 |
| chronic sublethal exposure to silver nanoparticles disrupts thyroid hormone signaling during xenopus laevis metamorphosis. | nanoparticles (nps) are engineered in the nanoscale (<100 nm) to have unique physico-chemical properties from their bulk counterparts. nanosilver particles (agnps) are the most prevalent nps in consumer products due to their strong antimicrobial action. while agnp toxicity at high concentrations has been thoroughly investigated, the sublethal effects at or below regulatory guidelines are relatively unknown. amphibian metamorphosis is mediated by thyroid hormone (th), and initial studies with bul ... | 2015 | 25531432 |
| baroreflex function in anurans from different environments. | anurans from terrestrial environments have an enhanced ability to maintain mean arterial blood pressure (p(m)) through lymph mobilization in response to desiccation or hemorrhage compared with semiaquatic or aquatic species. because short term blood pressure homeostasis is regulated by arterial baroreceptors, we compared baroreflex function in three species of anurans that span a range of environments, dehydration tolerance and an ability to maintain p(m) with dehydration and hemorrhage. the car ... | 2015 | 25447736 |
| enabling comparative gene expression studies of thyroid hormone action through the development of a flexible real-time quantitative pcr assay for use across multiple anuran indicator and sentinel species. | studies performed across diverse frog species have made substantial contributions to our understanding of basic vertebrate development and the natural or anthropogenic environmental factors impacting sensitive life stages. because, anurans are developmental models, provide ecosystems services, and act as sentinels for the identification of environmental chemical contaminants that interfere with thyroid hormone (th) action during postembryonic development, there is demand for flexible assessment ... | 2014 | 24503578 |
| cytochemical and immunocytochemical characterization of blood cells and immunohistochemical analysis of spleen cells from 2 species of frog, rana (aquarana) catesbeiana and xenopus laevis. | mechanisms of amphibian diseases are not characterized as well as those in domestic mammalian species. antemortem laboratory testing is limited in frogs, presenting a diagnostic challenge to zoos, laboratories, and exotic veterinarians. | 2012 | 22954297 |
| increased androgenic sensitivity in the hind limb muscular system marks the evolution of a derived gestural display. | physical gestures are prominent features of many species' multimodal displays, yet how evolution incorporates body and leg movements into animal signaling repertoires is unclear. androgenic hormones modulate the production of reproductive signals and sexual motor skills in many vertebrates; therefore, one possibility is that selection for physical signals drives the evolution of androgenic sensitivity in select neuromotor pathways. we examined this issue in the bornean rock frog (staurois parvus ... | 2016 | 27143723 |
| humane anesthesia and pain management in amphibian limb surgery of rana pipiens. | adult rana pipiens frogs are used as a model to investigate mechanisms of vertebrate organ regeneration, anti-tumor ribonucleases, zoological impacts of various pollutants, oncogenesis, neuroplasticity, and neurogenesis. in regenerative biology, the adult rana pipiens frog is an important alternative to other frog models, such as xenopus laevis, because it offers the opportunity to study and attempt to augment limb regeneration in an animal that spends significant time out of water and bears wei ... | 2013 | 23378649 |
| hensen's node, but not other biological signallers, can induce supernumerary digits in the developing chick limb bud. | the purpose of this study was to determine whether the organizer regions of early avian and amphibian embryos could induce supernumerary (sn) wing structures to develop when they were grafted to a slit in the anterior side of stage 19-23 chick wing buds. supernumerary digits developed in 43% of the wings that received anterior grafts of hensen's node from stage 4-6 quail or chick embryos; in addition, 16% of the wings had rods of sn cartilage, but not recognizable sn digits. the grafted quail ti ... | 1990 | 28305531 |
| suspension feeding dynamics of anuran larvae related to their functional morphology. | the tadpoles of two anuran species, rana sylvatica and xenopus laevis, were fed various concentrations of two algae, anabaena sphaerica (large filaments) and chlorella pyrenoidosa (small unicells). filtering rates were measured indirectly with a coulter counter system; buccal pumping rates were observed directly.experimental measurements of buccal volume (volume cleared with each pump stroke) agreed closely with independent predictions from a descriptive model based on tadpole morphology. the xe ... | 1979 | 28309170 |
| quantitative comparative analysis of the nasal chemosensory organs of anurans during larval development and metamorphosis highlights the relative importance of chemosensory subsystems in the group. | the anuran peripheral olfactory system is composed of a number of subsystems, represented by distinct neuroepithelia. these include the main olfactory epithelium and vomeronasal organ (found in most tetrapods) and three specialized epithelia of anurans: the buccal-exposed olfactory epithelium of larvae, and the olfactory recess and middle chamber epithelium of postmetamorphic animals. to better characterize the developmental changes in these subsystems across the life cycle, morphometric changes ... | 2017 | 28503895 |
| differences in mobility at the range edge of an expanding invasive population of xenopus laevis in the west of france. | theoretical models predict that spatial sorting at the range edge of expanding populations should favor individuals with increased mobility relative to individuals at the center of the range. despite the fact that empirical evidence for the evolution of locomotor performance at the range edge is rare, data on cane toads support this model. however, whether this can be generalized to other species remains largely unknown. here, we provide data on locomotor stamina and limb morphology in individua ... | 2017 | 28100805 |
| characterisation and vascular expression of nitric oxide synthase 3 in amphibians. | in mammals, nitric oxide (no) produced by nitric oxide synthase 3 (nos3) localised in vascular endothelial cells is an important vasodilator but the presence of nos3 in the endothelium of amphibians has been concluded to be absent, based on physiological studies. in this study, a nos3 cdna was sequenced from the toad, rhinella marina. the open reading frame of r. marina nos3 encoded an 1170 amino acid protein that showed 81 % sequence identity to the recently cloned xenopus tropicalis nos3. rhin ... | 2016 | 27543051 |
| acetyl-l-carnitine suppresses thyroid hormone-induced and spontaneous anuran tadpole tail shortening. | mitochondrial membrane permeability transition (mpt) plays a crucial role in apoptotic tail shortening during anuran metamorphosis. l-carnitine is known to shuttle free fatty acids (ffas) from the cytosol into mitochondria matrix for β-oxidation and energy production, and in a previous study we found that treatment with l-carnitine suppresses 3, 3', 5-triiodothyronine (t3 ) and ffa-induced mpt by reducing the level of ffas. in the present study we focus on acetyl-l-carnitine, which is also invol ... | 2013 | 23489246 |
| effects of chlorothalonil on development and growth of amphibian embryos and larvae. | chlorothalonil is a broad spectrum fungicide widely used in agricultural and urban environments, yet little is known regarding its effects on amphibians. we examined effects of chlorothalonil on growth, malformations, and mortality in embryos and larvae of xenopus laevis and spea multiplicata, and assessed variation in sensitivity among aquatic organisms using a species sensitivity distribution (ssd). chlorothalonil induced gut malformations in x. laevis embryos and inhibited growth. tail degene ... | 2013 | 23866729 |
| spemann-mangold grafts. | in 1924, hans spemann and hilde mangold (née pröscholdt) published their famous work describing the transplantation of dorsal blastopore lip of one newt gastrula embryo onto the ventral side of a host embryo at the same stage. they performed these grafts using two newt species with different pigmentation (triturus taeniatus and triturus cristatus) to follow the fate of the grafted tissue. these experiments resulted in the development of conjoined twins attached through their belly. because of th ... | 0 | 29321278 |
| peptidomic analysis of the extensive array of host-defense peptides in skin secretions of the dodecaploid frog xenopus ruwenzoriensis (pipidae). | the uganda clawed frog xenopus ruwenzoriensis with a karyotype of 2n=108 is one of the very few vertebrates with dodecaploid status. peptidomic analysis of norepinephrine-stimulated skin secretions from this species led to the isolation and structural characterization of 23 host-defense peptides belonging to the following families: magainin (3 peptides), peptide glycine-leucine-amide (pgla; 6 peptides), xenopsin precursor fragment (xpf; 3 peptides), caerulein precursor fragment (cpf; 8 peptides) ... | 2016 | 27290612 |
| genetics, morphology, advertisement calls, and historical records distinguish six new polyploid species of african clawed frog (xenopus, pipidae) from west and central africa. | african clawed frogs, genus xenopus, are extraordinary among vertebrates in the diversity of their polyploid species and the high number of independent polyploidization events that occurred during their diversification. here we update current understanding of the evolutionary history of this group and describe six new species from west and central sub-saharan africa, including four tetraploids and two dodecaploids. we provide information on molecular variation, morphology, karyotypes, vocalizati ... | 2015 | 26672747 |
| host-defense and trefoil factor family peptides in skin secretions of the mawa clawed frog xenopus boumbaensis (pipidae). | peptidomic analysis of norepinephrine-stimulated skin secretions from the octoploid mawa clawed frog xenopus boumbaensis loumont, 1983 led to the identification and characterization of 15 host-defense peptides belonging to the magainin (two peptides), peptide glycine-leucine-amide (pgla; three peptides), xenopsin precursor fragment (xpf; three peptides), caerulein precursor fragment (cpf; two peptides), and caerulein precursor fragment-related peptide (cpf-rp; five peptides) families. in additio ... | 2015 | 25849343 |
| xenopus borealis as an alternative source of oocytes for biophysical and pharmacological studies of neuronal ion channels. | for the past 30 years, oocytes from xenopus laevis have been extensively used to express and characterise ion channels in an easily controlled environment. here we report the first use of oocytes from the closely related species xenopus borealis as an alternative expression system for neuronal ion channels. using the two-electrode voltage-clamp technique, we show that a wide variety of voltage- and ligand-gated ion channels have the same channel properties and pharmacological profiles when expre ... | 2015 | 26440210 |
| a comparison of host-defense peptides in skin secretions of female xenopus laevis × xenopus borealis and x. borealis × x. laevis f1 hybrids. | peptidomic analysis was used to compare the diversity of host-defense peptides in norepinephrine-stimulated skin secretions from laboratory-generated female f1 hybrids of xenopus laevis and xenopus borealis (pipidae). skin secretions of hybrids with maternal x. laevis (xlb) contained 12 antimicrobial peptides (amps), comprising 8 from x. laevis and 4 from x. borealis. magainin-b1, xpf-b1, pgla-b1 cpf-b2, cpf-b3 and cpf-b4 from x. borealis and xpf-1, xpf-2, and cpf-6 from x. laevis were not detec ... | 2013 | 23624316 |
| distinct neural and neuromuscular strategies underlie independent evolution of simplified advertisement calls. | independent or convergent evolution can underlie phenotypic similarity of derived behavioural characters. determining the underlying neural and neuromuscular mechanisms sheds light on how these characters arose. one example of evolutionarily derived characters is a temporally simple advertisement call of male african clawed frogs (xenopus) that arose at least twice independently from a more complex ancestral pattern. how did simplification occur in the vocal circuit? to distinguish shared from d ... | 2013 | 23407829 |
| mesoderm induction in the future tail region of xenopus. | we have used interspecific grafts between xenopus borealis and xenopus laevis to study the signalling system that produces tail mesoderm. early gastrula ectoderm grafted into the posterior neural plate region of neurulae responds to a mesodermal inducing signal in this region and forms mainly tail somites; this signal persists until at least the early tail bud stage. ventral ectoderm grafted into the posterior neural plate loses its competence to respond to this signal after stage 10 1/2. we hav ... | 1988 | 28305752 |
| chromosome divergence during evolution of the tetraploid clawed frogs, xenopus mellotropicalis and xenopus epitropicalis as revealed by zoo-fish. | whole genome duplication (wgd) generates new species and genomic redundancy. in african clawed frogs of the genus xenopus, this phenomenon has been especially important in that (i) all but one extant species are polyploid and (ii) whole genome sequences of some species provide an evidence for genomic rearrangements prior to or after wgd. within xenopus in the subgenus silurana, at least one allotetraploidization event gave rise to three extant tetraploid (2n = 4x = 40) species-xenopus mellotropi ... | 2017 | 28545147 |
| caerulein precursor fragment (cpf) peptides from the skin secretions of xenopus laevis and silurana epitropicalis are potent insulin-releasing agents. | peptidomic analysis of norepinephrine-stimulated skin secretions of the tetraploid clawed frog xenopus laevis (pipidae) led to the identification of 10 peptides with the ability to stimulate the release of insulin from the rat brin-bd11 clonal β cell line. these peptides were purified to near homogeneity and structural characterization showed that they belong to the magainin (2 peptides), peptide glycine-leucine-amide (pgla) (1 peptide), xenopsin precursor fragment (1 peptide), and caerulein pre ... | 2013 | 23142129 |
| competition and feeding ecology in two sympatric xenopus species (anura: pipidae). | the widespread african clawed frog (xenopus laevis) occurs in sympatry with the iucn endangered cape platanna (xenopus gilli) throughout its entire range in the south-western cape, south africa. in order to investigate aspects of the interspecific competition between populations of x. laevis and x. gilli, an assessment of their niche differentiation was conducted through a comprehensive study on food composition and trophic niche structure at two study sites: the cape of good hope (cogh) and kle ... | 2017 | 28439453 |
| limited genomic consequences of hybridization between two african clawed frogs, xenopus gilli and x. laevis (anura: pipidae). | the cape platanna, xenopus gilli, an endangered frog, hybridizes with the african clawed frog, x. laevis, in south africa. estimates of the extent of gene flow between these species range from pervasive to rare. efforts have been made in the last 30 years to minimize hybridization between these two species in the west population of x. gilli, but not the east populations. to further explore the impact of hybridization and the efforts to minimize it, we examined molecular variation in one mitochon ... | 2017 | 28439068 |
| semi-solid tumor model in xenopus laevis/gilli cloned tadpoles for intravital study of neovascularization, immune cells and melanophore infiltration. | tumors have the ability to grow as a self-sustaining entity within the body. this autonomy is in part accomplished by the tumor cells ability to induce the formation of new blood vessels (angiogenesis) and by controlling cell trafficking inside the tumor mass. these abilities greatly reduce the efficacy of many cancer therapies and pose challenges for the development of more effective cancer treatments. hence, there is a need for animal models suitable for direct microscopy observation of blood ... | 2015 | 25601449 |
| evidence from peptidomic analysis of skin secretions that allopatric populations of xenopus gilli (anura:pipidae) constitute distinct lineages. | the international union for conservation of nature (iucn) endangered cape platanna xenopus gilli inhabits disjunct ranges at the tip of cape peninsula and near the town of kleinmond on opposite sides of false bay in the extreme southwest of africa. peptidomic analysis of host-defense peptides in norepinephrine-stimulated skin secretions from frogs from the cape peninsula range resulted in the identification of two magainins, two peptide glycine-leucine-amide (pgla) peptides, two xenopsin-precurs ... | 2015 | 25433327 |
| mind the gaps: investigating the cause of the current range disjunction in the cape platanna, xenopus gilli (anura: pipidae). | low-lying areas of the cape at africa's south-westernmost tip have undergone dramatic marine-remodelling, with regular changes in sea-level following glacial cycles. species for which marine barriers are impenetrable underwent concomitant radical distribution changes which may account for current range disjunctions. the cape platanna, xenopus gilli, is a frog distributed in only three disjunt areas within low-lying regions of the southwestern cape. we determined the relationship between frogs fr ... | 2013 | 24109551 |