Evolution of advertisement calls in African clawed frogs

Science.gov (United States)

Tobias, Martha L.; Evans, Ben J.; Kelley, Darcy B.

2014-01-01

Summary For most frogs, advertisement calls are essential for reproductive success, conveying information on species identity, male quality, sexual state and location. While the evolutionary divergence of call characters has been examined in a number of species, the relative impacts of genetic drift or natural and sexual selection remain unclear. Insights into the evolutionary trajectory of vocal signals can be gained by examining how advertisement calls vary in a phylogenetic context. Evolution by genetic drift would be supported if more closely related species express more similar songs. Conversely, a poor correlation between evolutionary history and song expression would suggest evolution shaped by natural or sexual selection. Here, we measure seven song characters in 20 described and two undescribed species of African clawed frogs (genera Xenopus and Silurana) and four populations of X. laevis. We identify three call types — click, burst and trill — that can be distinguished by click number, call rate and intensity modulation. A fourth type is biphasic, consisting of two of the above. Call types vary in complexity from the simplest, a click, to the most complex, a biphasic call. Maximum parsimony analysis of variation in call type suggests that the ancestral type was of intermediate complexity. Each call type evolved independently more than once and call type is typically not shared by closely related species. These results indicate that call type is homoplasious and has low phylogenetic signal. We conclude that the evolution of call type is not due to genetic drift, but is under selective pressure. PMID:24723737

Connexins in the early development of the African clawed frog Xenopus laevis (Amphibia: The role of the connexin43 carboxyl terminal tail in the establishment of the dorso-ventral axis

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Jaime Cofre

2007-03-01

Full Text Available Connexins are a family of related proteins identified in vertebrate forming gap junctions, which mediate cell-to-cell communication in early embryos, with an important role in establishing embryonic asymmetry and ‘communication compartments’. By in situ hybridization, immunocytochemistry, reverse transcriptase PCR (RT-PCR and western blotting we show that a Cx43-like molecule is present in oocytes and embryos of the African clawed frog Xenopus laevis, with specific localization in the animal-vegetal axis. This specific distribution is suggestive for an important role for this protein in the establishment of the dorso-ventral axis. Antisense RNA and antibodies directed against rat carboxyl terminal tail of the Cx43 (CT-Cx43 and injected in 1-cell stage Xenopus embryos, induced pronounced alterations in nervous system development, with a severe ventralization phenotype. Coherently, the overexpression of CT-Cx43 produced a dorsalization of the embryos. In antisense treated embryos, the expression of the beta-catenin gene is eliminated from the Nieuwkoop center, the pattern expression of the Chordin, Xnot and Xbra is modified, with no effect in expression of the Goosecoid gene. In CT-Cx43 mRNA treated embryos the pattern of expression of the beta-catenin, Chordin, Goosecoid, Xnot and engrailed-2 genes is modified. The expression of beta-catenin is increased in the Nieuwkoop center, the expression pattern of Chordin and Goosecoid is expanded to the posterior neural plate and engrailed-2 presents ectopic expression in the ventral region. Taken together our data suggest a role for CT-Cx43 as a maternal determinant with a critical function in the formation of the dorso-ventral axis in Xenopus laevis. The Cx43 may be one of the earliest markers of the dorso-ventral axis in these embryos and could possibly be acting through regionalization of factors responsible for the establishment of this axis.

Structure-related effects of pyrethroid insecticides on the lateral-line sense organ and on peripheral nerves of the clawed frog, Xenopus laevis

NARCIS (Netherlands)

Vijverberg, H.P.M.; Ruigt, GeS. F.; Bercken, J. van den

1982-01-01

The effects of seven different pyrethroid insecticides on the lateral-line sense organ and on peripheral nerves of the clawed frog, Xenopus laevis, were investigated by means of electrophysiological methods. The results show that two classes of pyrethroid can be clearly distinguished. (i)

Urotensin II receptor (UTR) exists in hyaline chondrocytes: a study of peripheral distribution of UTR in the African clawed frog, Xenopus laevis.

Science.gov (United States)

Konno, Norifumi; Fujii, Yuya; Imae, Haruka; Kaiya, Hiroyuki; Mukuda, Takao; Miyazato, Mikiya; Matsuda, Kouhei; Uchiyama, Minoru

2013-05-01

Urotensin II (UII) and UII-related peptide (URP) exhibit diverse physiological actions including vasoconstriction, locomotor activity, osmoregulation, and immune response through UII receptor (UTR), which is expressed in the central nervous system and peripheral tissues of fish and mammals. In amphibians, only UII has been identified. As the first step toward elucidating the actions of UII and URP in amphibians, we cloned and characterized URP and UTR from the African clawed frog Xenopus laevis. Functional analysis showed that treatment of UII or URP with Chinese hamster ovary cells transfected with the cloned receptor increased the intracellular calcium concentration in a concentration-dependent manner, whereas the administration of the UTR antagonist urantide inhibited UII- or URP-induced Ca(2+) mobilization. An immunohistochemical study showed that UTR was expressed in the splenocytes and leukocytes isolated from peripheral blood, suggesting that UII and URP are involved in the regulation of the immune system. UTR was also localized in the apical membrane of the distal tubule of the kidney and in the transitional epithelial cells of the urinary bladder. This result supports the view that the UII/URP-UTR system plays an important role in osmoregulation of amphibians. Interestingly, immunopositive labeling for UTR was first detected in the chondrocytes of various hyaline cartilages (the lung septa, interphalangeal joint and sternum). The expression of UTR was also observed in the costal cartilage, tracheal cartilages, and xiphoid process of the rat. These novel findings probably suggest that UII and URP mediate the formation of the cartilaginous matrix. Copyright © 2013 Elsevier Inc. All rights reserved.

A model for investigating developmental eye repair in Xenopus laevis.

Science.gov (United States)

Kha, Cindy X; Son, Philip H; Lauper, Julia; Tseng, Kelly Ai-Sun

2018-04-01

Vertebrate eye development is complex and requires early interactions between neuroectoderm and surface ectoderm during embryogenesis. In the African clawed frog, Xenopus laevis, individual eye tissues such as the retina and lens can undergo regeneration. However, it has been reported that removal of either the specified eye field at the neurula stage or the eye during tadpole stage does not induce replacement. Here we describe a model for investigating Xenopus developmental eye repair. We found that tailbud embryos can readily regrow eyes after surgical removal of over 83% of the specified eye and lens tissues. The regrown eye reached a comparable size to the contralateral control by 5 days and overall animal development was normal. It contained the expected complement of eye cell types (including the pigmented epithelium, retina and lens), and is connected to the brain. Our data also demonstrate that apoptosis, an early mechanism that regulates appendage regeneration, is also required for eye regrowth. Treatment with apoptosis inhibitors (M50054 or NS3694) blocked eye regrowth by inhibiting caspase activation. Together, our findings indicate that frog embryos can undergo successful eye repair after considerable tissue loss and reveals a required role for apoptosis in this process. Furthermore, this Xenopus model allows for rapid comparisons of productive eye repair and developmental pathways. It can also facilitate the molecular dissection of signaling mechanisms necessary for initiating repair. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Assessment of mutagenic damage by monofunctional alkylating agents and gamma radiation in haploid and diploid frogs, Xenopus laevis

International Nuclear Information System (INIS)

Hart, D.R.; Armstrong, J.B.

1984-01-01

Adult male South African clawed frogs, Xenopus laevis, were mutagenized by 3-day immersion in aqueous solutions of ethyl methanesulfonate (EMS), diethyl nitrosamine (DEN), or ethyl nitrosourea (ENU), or by acute exposure to gamma radiation. They were then spawned repeatedly at 2-week intervals with untreated females, and embryonic survival of the progeny was used to assess genetic damage. Recessive lethal effects were assessed from reduced survival of androgenetic haploid progeny. Neither recessive nor dominant lethal effects were obtained after exposure to 100 mg/liter EMS or 2 g/liter DEN. At 250 mg/liter EMS, peak dominant lethality occurred 3-5 weeks after treatment. Most embryos hatched, but many were abnormal and died shortly after hatching. Haploid survival was significantly reduced over a broader period, from 1 to 13 weeks after mutagenesis. Treatment with 75 mg/liter ENU produced effects similar to the 250-mg/liter EMS mutagenesis. At 400 mg/liter EMS, the frequency and severity of the effects on both diploid and haploid embryos were increased over the lower dose. Gamma irradiation at 1500 R produced effects similar to the 400-mg/liter mutagenesis, except that peak dominant lethality extended from 1 to 7 weeks

Comparative Analysis of Cartilage Marker Gene Expression Patterns during Axolotl and Xenopus Limb Regeneration.

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Kazumasa Mitogawa

Full Text Available 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 patterning defect in Xenopus frog limb regeneration were explored. We hypothesized that differences in chondrogenesis may underlie the patterning defect. Thus, we focused on chondrogenesis. Chondrogenesis marker genes, type I and type II collagen, were compared in regenerative and nonregenerative environments. There were marked differences between axolotls and Xenopus in the expression pattern of these chondrogenesis-associated genes. The relative deficit in the chondrogenic capacity of Xenopus blastema cells may account for the absence of total limb regenerative capacity.

Targeted integration of genes in Xenopus tropicalis

DEFF Research Database (Denmark)

Shi, Zhaoying; Tian, Dandan; Xin, Huhu

2017-01-01

With the successful establishment of both targeted gene disruption and integration methods in the true diploid frog Xenopus tropicalis, this excellent vertebrate genetic model now is making a unique contribution to modelling human diseases. Here, we summarize our efforts on establishing homologous...... recombination-mediated targeted integration in Xenopus tropicalis, the usefulness, and limitation of targeted integration via the homology-independent strategy, and future directions on how to further improve targeted gene integration in Xenopus tropicalis....

Use of the enhanced frog embryo teratogenesis assay-Xenopus (FETAX) to determine chemically-induced phenotypic effects.

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Hu, Lingling; Zhu, Jingmin; Rotchell, Jeanette M; Wu, Lijiao; Gao, Jinjuan; Shi, Huahong

2015-03-01

The frog embryo teratogenesis assay-Xenopus (FETAX) is an established method for the evaluation of the developmental toxicities of chemicals. To develop an enhanced FETAX that is appropriate for common environmental contaminants, we exposed Xenopus tropicalis embryos to eight compounds, including tributyltin, triphenyltin, CdCl2, pyraclostrobin, picoxystrobin, coumoxystrobin, all-trans-retinoic acid and 9-cis-retinoic acid. Multiple malformations were induced in embryos particularly following exposure to tributyltin, triphenyltin and pyraclostrobin at environmentally relevant concentrations. Based on the range of observed malformations, we proposed a phenotypic assessment method with 20 phenotypes and a 0-5 scoring system. This derived index exhibited concentration-dependent relationships for all of the chemicals tested. Furthermore, the phenotype profiles were characteristic of the different tested chemicals. Our results indicate that malformation phenotypes can be quantitatively integrated with the primary endpoints in conventional FETAX assessments to allow for increased sensitivity and measurement of quantitative effects and to provide indicative mechanistic information for each tested chemical. Copyright © 2014 Elsevier B.V. All rights reserved.

The Sperm-surface glycoprotein, SGP, is necessary for fertilization in the frog, Xenopus laevis.

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Nagai, Keita; Ishida, Takuya; Hashimoto, Takafumi; Harada, Yuichirou; Ueno, Shuichi; Ueda, Yasushi; Kubo, Hideo; Iwao, Yasuhiro

2009-06-01

To identify a molecule involved in sperm-egg plasma membrane binding at fertilization, a monoclonal antibody against a sperm-surface glycoprotein (SGP) was obtained by immunizing mice with a sperm membrane fraction of the frog, Xenopus laevis, followed by screening of the culture supernatants based on their inhibitory activity against fertilization. The fertilization of both jellied and denuded eggs was effectively inhibited by pretreatment of sperm with intact anti-SGP antibody as well as its Fab fragment, indicating that the antibody recognizes a molecule on the sperm's surface that is necessary for fertilization. On Western blots, the anti-SGP antibody recognized large molecules, with molecular masses of 65-150 kDa and minor smaller molecules with masses of 20-28 kDa in the sperm membrane vesicles. SGP was distributed over nearly the entire surface of the sperm, probably as an integral membrane protein in close association with microfilaments. More membrane vesicles containing SGP bound to the surface were found in the animal hemisphere compared with the vegetal hemisphere in unfertilized eggs, but the vesicle-binding was not observed in fertilized eggs. These results indicate that SGP mediates sperm-egg membrane binding and is responsible for the establishment of fertilization in Xenopus.

In-cell NMR spectroscopy of proteins inside Xenopus laevis oocytes

International Nuclear Information System (INIS)

Sakai, Tomomi; Tochio, Hidehito; Tenno, Takeshi; Ito, Yutaka; Kokubo, Tetsuro; Hiroaki, Hidekazu; Shirakawa, Masahiro

2006-01-01

In-cell NMR is an application of solution NMR that enables the investigation of protein conformations inside living cells. We have measured in-cell NMR spectra in oocytes from the African clawed frog Xenopus laevis. 15 N-labeled ubiquitin, its derivatives and calmodulin were injected into Xenopus oocytes and two-dimensional 1 H- 15 N correlation spectra of the proteins were obtained. While the spectrum of wild-type ubiquitin in oocytes had rather fewer cross-peaks compared to its in vitro spectrum, ubiquitin derivatives that are presumably unable to bind to ubiquitin-interacting proteins gave a markedly larger number of cross-peaks. This observation suggests that protein-protein interactions between ubiquitin and ubiquitin-interacting proteins may cause NMR signal broadening, and hence spoil the quality of the in-cell HSQC spectra. In addition, we observed the maturation of ubiquitin precursor derivative in living oocytes using the in-cell NMR technique. This process was partly inhibited by pre-addition of ubiquitin aldehyde, a specific inhibitor for ubiquitin C-terminal hydrolase (UCH). Our work demonstrates the potential usefulness of in-cell NMR with Xenopus oocytes for the investigation of protein conformations and functions under intracellular environmental conditions

Population-specific incidence of testicular ovarian follicles in Xenopus laevis from South Africa: A potential issue in endocrine testing

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Du Preez, Louis H., E-mail: Louis.DuPreez@nwu.ac.za [School of Environmental Sciences and Development, North-West University, Potchefstroom 2531 (South Africa); Kunene, Nisile [School of Environmental Sciences and Development, North-West University, Potchefstroom 2531 (South Africa); Hanner, Robert [Department of Integrative Biology, University of Guelph, Guelph, ON, N1G 2W1 (Canada); Giesy, John P. [Department of Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, Saskatchewan (Canada); Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (Hong Kong); National Food Safety and Toxicology Center, Zoology Department, and Centre for Integrative Toxicology, Michigan State University, East Lansing, MI 48824 (United States); Solomon, Keith R., E-mail: ksolomon@uoguelph.ca [Centre for Toxicology and Department of Environmental Biology, University of Guelph, Guelph, ON, N1G 2W1 (Canada); Hosmer, Alan [Syngenta Crop Protection, Greensboro, NC 27419-8300 (United States); Van Der Kraak, Glen J. [Department of Integrative Biology, University of Guelph, Guelph, ON, N1G 2W1 (Canada)

2009-10-19

The African clawed frog (Xenopus laevis) has been identified as an appropriate sentinel for testing endocrine activity of existing chemicals in North America and Europe. Some reports suggest that the herbicide, atrazine (CAS Number [1912-24-9]) causes ovarian follicles to form in the testes of this frog. X. laevis collected from North East (NE) sites in South Africa had testicular ovarian follicles, irrespective of exposure to atrazine, while frogs from Southwest Western (SW) Cape region sites had none. Phylogenetic analysis of mitochondrial and nuclear genes indicates that frogs from the SW Cape are evolutionarily divergent from those from NE South Africa and the rest of sub-Saharan Africa. These findings provide a possible explanation for why conflicting results have been reported concerning the impact of atrazine on amphibian sexual differentiation and highlight the importance of understanding taxonomic status of the experimental animal. Even in common laboratory animals, there is a need for their correct taxonomic characterization before their use in tests for endocrine disruption.

Population-specific incidence of testicular ovarian follicles in Xenopus laevis from South Africa: A potential issue in endocrine testing

International Nuclear Information System (INIS)

Du Preez, Louis H.; Kunene, Nisile; Hanner, Robert; Giesy, John P.; Solomon, Keith R.; Hosmer, Alan; Van Der Kraak, Glen J.

2009-01-01

The African clawed frog (Xenopus laevis) has been identified as an appropriate sentinel for testing endocrine activity of existing chemicals in North America and Europe. Some reports suggest that the herbicide, atrazine (CAS Number [1912-24-9]) causes ovarian follicles to form in the testes of this frog. X. laevis collected from North East (NE) sites in South Africa had testicular ovarian follicles, irrespective of exposure to atrazine, while frogs from Southwest Western (SW) Cape region sites had none. Phylogenetic analysis of mitochondrial and nuclear genes indicates that frogs from the SW Cape are evolutionarily divergent from those from NE South Africa and the rest of sub-Saharan Africa. These findings provide a possible explanation for why conflicting results have been reported concerning the impact of atrazine on amphibian sexual differentiation and highlight the importance of understanding taxonomic status of the experimental animal. Even in common laboratory animals, there is a need for their correct taxonomic characterization before their use in tests for endocrine disruption.

Expression of the adhesion G protein-coupled receptor A2 (adgra2) during Xenopus laevis development.

Science.gov (United States)

Seigfried, Franziska A; Dietmann, Petra; Kühl, Michael; Kühl, Susanne J

2018-06-01

The adhesion G protein-coupled receptor A2 (Adgra2) is a seven transmembrane receptor that has been described to be a regulator for angiogenesis in mice. Furthermore, the zebrafish ouchless mutant is unable to develop dorsal root ganglia through a disrupted trafficking of Adgra2. Besides RNA sequencing data, nothing is reported about Adgra2 in the south African crawled frog Xenopus laevis. In this study, we investigated for the first time the spatio-temporal expression of adgra2 during early Xenopus embryogenesis in detail. In silico approaches showed that the genomic adgra2 region as well as the Adgra2 protein sequence is highly conserved among different species including Xenopus. RT-PCR experiments confirmed that embryonic adgra2 expression is primarily detected at the beginning of neurulation and is then present throughout the whole Xenopus embryogenesis until stage 42. Whole mount in situ hybridization approaches visualized adgra2 expression in many tissues during Xenopus embryogenesis such as the cardiovascular system including the heart, the migrating neural crest cells and the developing eye including the periocular mesenchyme. Our results indicate a role of Adgra2 for embryogenesis and are a good starting point for further functional studies during early vertebrate development. Copyright © 2018 Elsevier B.V. All rights reserved.

Sublethal Toxic Effects and Induction of gGutathione S-transferase by Short-Chain Chlorinated Paraffins (SCCPs) and C-12 alkane (dodecane) in Xenopus laevis Frog Embryos

OpenAIRE

B. Burýšková; L. Bláha; D. Vršková; K. Šimková; B. Maršálek

2006-01-01

Short chain chlorinated paraffins (SCCPs) are important industrial chemicals with high persistence in the environment but poorly characterized ecotoxicological effects. We studied embryotoxic effects of commercial mixture of SCCP (carbon length C-12, 56% of chlorine; CP56-12) and non-chlorinated n-alkane (dodecane, C-12) in the 96h Frog Embryo Teratogenesis Assay - Xenopus (FETAX). Only weak lethal effects were observed for both substances (the highest tested concentration 500 mg/L of both ch...

Developing Xenopus Embryos Recover by Compacting and Expelling Single-Wall Carbon Nanotubes

Science.gov (United States)

Holt, Brian D.; Shawky, Joseph H.; Dahl, Kris Noel; Davidson, Lance A.; Islam, Mohammad F.

2015-01-01

Single-wall carbon nanotubes are high aspect ratio nanomaterials that are being developed for use in materials, technological and biological applications due to their high mechanical stiffness, optical properties, and chemical inertness. Because of their prevalence, it is inevitable that biological systems will be exposed to nanotubes, yet studies of the effects of nanotubes on developing embryos have been inconclusive and are lacking for single-wall carbon nanotubes exposed to the widely studied model organism Xenopus laevis (African clawed frog). Microinjection of experimental substances into the Xenopus embryo is a standard technique for toxicology studies and cellular lineage tracing. Here we report the surprising finding that superficial (12.5 ± 7.5 μm below the membrane) microinjection of nanotubes dispersed with Pluronic F127 into one-to-two cell Xenopus embryos resulted in the formation and expulsion of compacted, nanotube-filled, punctate masses, at the blastula to mid-gastrula developmental stages, which we call “boluses”. Such expulsion of microinjected materials by Xenopus embryos has not been reported before and is dramatically different from the typical distribution of the materials throughout the progeny of the microinjected cells. Previous studies of microinjections of nanomaterials such as nanodiamonds, quantum dots or spherical nanoparticles report that nanomaterials often induce toxicity and remain localized within the embryos. In contrast, our results demonstrate an active recovery pathway for embryos after exposure to Pluronic F127-coated nanotubes, which we speculate is due to a combined effect of the membrane activity of the dispersing agent, Pluronic F127, and the large aspect ratio of nanotubes. PMID:26153061

Developing Xenopus embryos recover by compacting and expelling single wall carbon nanotubes.

Science.gov (United States)

Holt, Brian D; Shawky, Joseph H; Dahl, Kris Noel; Davidson, Lance A; Islam, Mohammad F

2016-04-01

Single wall carbon nanotubes are high aspect ratio nanomaterials being developed for use in materials, technological and biological applications due to their high mechanical stiffness, optical properties and chemical inertness. Because of their prevalence, it is inevitable that biological systems will be exposed to nanotubes, yet studies of the effects of nanotubes on developing embryos have been inconclusive and are lacking for single wall carbon nanotubes exposed to the widely studied model organism Xenopus laevis (African clawed frog). Microinjection of experimental substances into the Xenopus embryo is a standard technique for toxicology studies and cellular lineage tracing. Here we report the surprising finding that superficial (12.5 ± 7.5 µm below the membrane) microinjection of nanotubes dispersed with Pluronic F127 into one- to two-cell Xenopus embryos resulted in the formation and expulsion of compacted, nanotube-filled, punctate masses, at the blastula to mid-gastrula developmental stages, which we call "boluses." Such expulsion of microinjected materials by Xenopus embryos has not been reported before and is dramatically different from the typical distribution of the materials throughout the progeny of the microinjected cells. Previous studies of microinjections of nanomaterials such as nanodiamonds, quantum dots or spherical nanoparticles report that nanomaterials often induce toxicity and remain localized within the embryos. In contrast, our results demonstrate an active recovery pathway for embryos after exposure to Pluronic F127-coated nanotubes, which we speculate is due to a combined effect of the membrane activity of the dispersing agent, Pluronic F127, and the large aspect ratio of nanotubes. Copyright © 2015 John Wiley & Sons, Ltd.

Xenopus iaevis (Anura: Pipidae) Mating systems - A preliminary ...

African Journals Online (AJOL)

was inhibited if the frogs were injected with saline to simulate ripe ovaries. Russel (1954) described a low frequency tremor given by males when in amplexus with females. This behaviour was also noted by Grimm (1952). Although many authors have provided verbal or phonetic descriptions of the calls of Xenopus laevis, ...

First parasitological study of the African clawed frog (Xenopus laevis, Amphibia in Chile

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Cristóbal Castillo

Full Text Available Abstract Introduced species can arrive into new territories with parasites; however, these species are expected to face lower parasite richness than in their original regions. Both introduced hosts and parasites can affect native fauna. Since their release into the wild in Chile following laboratory use, Xenopus laevis Daudin, 1802 has widely spread throughout central Chile. The only pathogen described on the host is the fungus Batrachochytrium dendrobatidis Longcore, Pessier, Nichols, 1999; thus, this is the first parasitological study of this species in Chile. In 10 localities in central Chile, 179 specimens of X. laevis were captured and examined for parasites in the gastrointestinal tube, cavities, lungs, liver, and skin. Only nine specimens of the genus Contracaecum Railliet, Henry, 1912 were found in six specimens of X. laevis from a private dam in La Patagua. It is likely that these parasites originated from species of native birds. This is the first record of Contracaecum sp. in Chilean amphibians.

Whole-genome sequence of the Tibetan frog Nanorana parkeri and the comparative evolution of tetrapod genomes.

Science.gov (United States)

Sun, Yan-Bo; Xiong, Zi-Jun; Xiang, Xue-Yan; Liu, Shi-Ping; Zhou, Wei-Wei; Tu, Xiao-Long; Zhong, Li; Wang, Lu; Wu, Dong-Dong; Zhang, Bao-Lin; Zhu, Chun-Ling; Yang, Min-Min; Chen, Hong-Man; Li, Fang; Zhou, Long; Feng, Shao-Hong; Huang, Chao; Zhang, Guo-Jie; Irwin, David; Hillis, David M; Murphy, Robert W; Yang, Huan-Ming; Che, Jing; Wang, Jun; Zhang, Ya-Ping

2015-03-17

The development of efficient sequencing techniques has resulted in large numbers of genomes being available for evolutionary studies. However, only one genome is available for all amphibians, that of Xenopus tropicalis, which is distantly related from the majority of frogs. More than 96% of frogs belong to the Neobatrachia, and no genome exists for this group. This dearth of amphibian genomes greatly restricts genomic studies of amphibians and, more generally, our understanding of tetrapod genome evolution. To fill this gap, we provide the de novo genome of a Tibetan Plateau frog, Nanorana parkeri, and compare it to that of X. tropicalis and other vertebrates. This genome encodes more than 20,000 protein-coding genes, a number similar to that of Xenopus. Although the genome size of Nanorana is considerably larger than that of Xenopus (2.3 vs. 1.5 Gb), most of the difference is due to the respective number of transposable elements in the two genomes. The two frogs exhibit considerable conserved whole-genome synteny despite having diverged approximately 266 Ma, indicating a slow rate of DNA structural evolution in anurans. Multigenome synteny blocks further show that amphibians have fewer interchromosomal rearrangements than mammals but have a comparable rate of intrachromosomal rearrangements. Our analysis also identifies 11 Mb of anuran-specific highly conserved elements that will be useful for comparative genomic analyses of frogs. The Nanorana genome offers an improved understanding of evolution of tetrapod genomes and also provides a genomic reference for other evolutionary studies.

Ubiquitin-mediated proteolysis in Xenopus extract.

Science.gov (United States)

McDowell, Gary S; Philpott, Anna

2016-01-01

The small protein modifier, ubiquitin, can be covalently attached to proteins in the process of ubiquitylation, resulting in a variety of functional outcomes. In particular, the most commonly-associated and well-studied fate for proteins modified with ubiquitin is their ultimate destruction: degradation by the 26S proteasome via the ubiquitin-proteasome system, or digestion in lysosomes by proteolytic enzymes. From the earliest days of ubiquitylation research, a reliable and versatile "cell-in-a-test-tube" system has been employed in the form of cytoplasmic extracts from the eggs and embryos of the frog Xenopus laevis. Biochemical studies of ubiquitin and protein degradation using this system have led to significant advances particularly in the study of ubiquitin-mediated proteolysis, while the versatility of Xenopus as a developmental model has allowed investigation of the in vivo consequences of ubiquitylation. Here we describe the use and history of Xenopus extract in the study of ubiquitin-mediated protein degradation, and highlight the versatility of this system that has been exploited to uncover mechanisms and consequences of ubiquitylation and proteolysis.

Antifungal activity of epithelial secretions from selected frog species ...

African Journals Online (AJOL)

This study aimed to investigate the antifungal activity of skin secretions from selected frogs (Amietia fuscigula, Strongylopus grayi and Xenopus laevis) and one toad (Amietophrynus pantherinus) of the south Western Cape Province of South Africa. Initially, different extraction techniques for the collection of skin secretions ...

Cytoskeleton and Cytoskeleton-Bound RNA Visualization in Frog and Insect Oocytes.

Science.gov (United States)

Kloc, Malgorzata; Bilinski, Szczepan; Kubiak, Jacek Z

2016-01-01

The majority of oocyte functions involves and depends on the cytoskeletal elements, which include microtubules and actin and cytokeratin filaments. Various structures and molecules are temporarily or permanently bound to the cytoskeletal elements and their functions rely on cytoskeleton integrity and its timely assembly. Thus the accurate visualization of cytoskeleton is often crucial for studies and analyses of oocyte structure and functions. Here we describe several reliable methods for microtubule and/or microfilaments preservation and visualization in Xenopus oocyte extracts, and in situ in live and fixed insect and frog (Xenopus) oocytes. In addition, we describe visualization of cytoskeleton-bound RNAs using molecular beacons in live Xenopus oocytes.

Sublethal Toxic Effects and Induction of gGutathione S-transferase by Short-Chain Chlorinated Paraffins (SCCPs and C-12 alkane (dodecane in Xenopus laevis Frog Embryos

Directory of Open Access Journals (Sweden)

B. Burýšková

2006-01-01

Full Text Available Short chain chlorinated paraffins (SCCPs are important industrial chemicals with high persistence in the environment but poorly characterized ecotoxicological effects. We studied embryotoxic effects of commercial mixture of SCCP (carbon length C-12, 56% of chlorine; CP56-12 and non-chlorinated n-alkane (dodecane, C-12 in the 96h Frog Embryo Teratogenesis Assay - Xenopus (FETAX. Only weak lethal effects were observed for both substances (the highest tested concentration 500 mg/L of both chemicals caused up to 11% mortality. On the other hand, we observed developmental malformations and reduced embryo growth at 5 mg/l and higher concentrations. However, the effects were not related to chlorination pattern as both SCCPs and dodecane induced qualitatively similar effects. SCCPs also significantly induced phase II detoxification enzyme glutathione S-transferase (GST in Xenopus laevis embryos even at 0.5 mg/L, and this biomarker might be used as another early warning of chronic toxic effects. Our results newly indicate significant developmental toxicity of both SCCPs and n-dodecane to aquatic organisms along with inductions of specific biochemical toxicity mechanisms.

Hyperinnervation improves Xenopus laevis limb regeneration.

Science.gov (United States)

Mitogawa, Kazumasa; Makanae, Aki; Satoh, Akira

2018-01-15

Xenopus laevis (an anuran amphibian) shows limb regeneration ability between that of urodele amphibians and that of amniotes. Xenopus frogs can initiate limb regeneration but fail to form patterned limbs. Regenerated limbs mainly consist of cone-shaped cartilage without any joints or branches. These pattern defects are thought to be caused by loss of proper expressions of patterning-related genes. This study shows that hyperinnervation surgery resulted in the induction of a branching regenerate. The hyperinnervated blastema allows the identification and functional analysis of the molecules controlling this patterning of limb regeneration. This paper focuses on the nerve affects to improve Xenopus limb patterning ability during regeneration. The nerve molecules, which regulate limb patterning, were also investigated. Blastemas grown in a hyperinnervated forelimb upregulate limb patterning-related genes (shh, lmx1b, and hoxa13). Nerves projecting their axons to limbs express some growth factors (bmp7, fgf2, fgf8, and shh). Inputs of these factors to a blastema upregulated some limb patterning-related genes and resulted in changes in the cartilage patterns in the regenerates. These results indicate that additional nerve factors enhance Xenopus limb patterning-related gene expressions and limb regeneration ability, and that bmp, fgf, and shh are candidate nerve substitute factors. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

More similar than you think: Frog metamorphosis as a model of human perinatal endocrinology.

Science.gov (United States)

Buchholz, Daniel R

2015-12-15

Hormonal control of development during the human perinatal period is critically important and complex with multiple hormones regulating fetal growth, brain development, and organ maturation in preparation for birth. Genetic and environmental perturbations of such hormonal control may cause irreversible morphological and physiological impairments and may also predispose individuals to diseases of adulthood, including diabetes and cardiovascular disease. Endocrine and molecular mechanisms that regulate perinatal development and that underlie the connections between early life events and adult diseases are not well elucidated. Such mechanisms are difficult to study in uterus-enclosed mammalian embryos because of confounding maternal effects. To elucidate mechanisms of developmental endocrinology in the perinatal period, Xenopus laevis the African clawed frog is a valuable vertebrate model. Frogs and humans have identical hormones which peak at birth and metamorphosis, have conserved hormone receptors and mechanisms of gene regulation, and have comparable roles for hormones in many target organs. Study of molecular and endocrine mechanisms of hormone-dependent development in frogs is advantageous because an extended free-living larval period followed by metamorphosis (1) is independent of maternal endocrine influence, (2) exhibits dramatic yet conserved developmental effects induced by thyroid and glucocorticoid hormones, and (3) begins at a developmental stage with naturally undetectable hormone levels, thereby facilitating endocrine manipulation and interpretation of results. This review highlights the utility of frog metamorphosis to elucidate molecular and endocrine actions, hormone interactions, and endocrine disruption, especially with respect to thyroid hormone. Knowledge from the frog model is expected to provide fundamental insights to aid medical understanding of endocrine disease, stress, and endocrine disruption affecting the perinatal period in humans

A Method for Mechanism Analysis of Frog Swimming Based on Motion Observation Experiments

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Wei Zhang

2014-05-01

Full Text Available For understanding the mechanism of frog swimming under water and designing a frog-inspired swimming robot, kinematics of the frog body and trajectories of joints should be obtained. In this paper, an aquatic frog, Xenopus laevis, was chosen for analysis of swimming motions which were recorded by a high speed camera, and kinematic data were processed in a swimming data extraction platform. According to the shape features of the frog, we propose a method that the frog eyes are set as the natural data extraction markers for body motion, and kinematic data of joint trajectories are calculated by the contour points on the limbs. For the data processing, a pinhole camera model was built to transform the pixel coordinate system to world coordinate system, and the errors caused by the water refraction were analyzed and corrected. Finally, from the developed data extraction platform, the kinematic data for the analysis of swimming mechanism and design of frog-inspired robot were obtained.

Identification of genes associated with regenerative success of Xenopus laevis hindlimbs

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Barker Donna

2008-06-01

Full Text Available Abstract Background Epimorphic regeneration is the process by which complete regeneration of a complex structure such as a limb occurs through production of a proliferating blastema. This type of regeneration is rare among vertebrates but does occur in the African clawed frog Xenopus laevis, traditionally a model organism for the study of early development. Xenopus tadpoles can regenerate their tails, limb buds and the lens of the eye, although the ability of the latter two organs to regenerate diminishes with advancing developmental stage. Using a heat shock inducible transgene that remains silent unless activated, we have established a stable line of transgenic Xenopus (strain N1 in which the BMP inhibitor Noggin can be over-expressed at any time during development. Activation of this transgene blocks regeneration of the tail and limb of Xenopus tadpoles. Results In the current study, we have taken advantage of the N1 transgenic line to directly compare morphology and gene expression in same stage regenerating vs. BMP signalling deficient non-regenerating hindlimb buds. The wound epithelium of N1 transgenic hindlimb buds, which forms over the cut surface of the limb bud after amputation, does not transition normally into the distal thickened apical epithelial cap. Instead, a basement membrane and dermis form, indicative of mature skin. Furthermore, the underlying mesenchyme remains rounded and does not expand to form a cone shaped blastema, a normal feature of successful regeneration. Using Affymetrix Gene Chip analysis, we have identified genes linked to regenerative success downstream of BMP signalling, including the BMP inhibitor Gremlin and the stress protein Hsp60 (no blastema in zebrafish. Gene Ontology analysis showed that genes involved in embryonic development and growth are significantly over-represented in regenerating early hindlimb buds and that successful regeneration in the Xenopus hindlimb correlates with the induction of

Tissue distribution of enrofloxacin in African clawed frogs (Xenopus laevis) after intramuscular and subcutaneous administration.

Science.gov (United States)

Felt, Stephen; Papich, Mark G; Howard, Antwain; Long, Tyler; McKeon, Gabriel; Torreilles, Stéphanie; Green, Sherril

2013-03-01

As part of an enrofloxacin pharmacokinetic study, concentrations of enrofloxacin and ciprofloxacin (metabolite) were measured in various tissues (brain, heart, kidney, liver, lung, and spleen) collected from treated (subcutaneous delivery, n = 3; intramuscular delivery, n = 3; untreated controls, n = 2) adult female Xenopus laevis by using HPLC. Enrofloxacin was rapidly absorbed after administration by either route and readily diffused into all sampled tissues. Enrofloxacin and ciprofloxacin were present in the tissue samples collected at 8 h. The highest average tissue concentrations for enrofloxacin were found in kidney, with the lowest concentrations in liver. Ciprofloxacin tissue concentrations paralleled but were always lower than those of enrofloxacin for all time points and tissues except brain and kidney. These results, together with previously published pharmacokinetic data and known minimal inhibitory concentrations of common pathogenic bacteria, provide a strong evidence-based rationale for choosing enrofloxacin to treat infectious diseases in X. laevis.

Adaptive immunity and histopathology in frog virus 3-infected Xenopus

International Nuclear Information System (INIS)

Robert, Jacques; Morales, Heidi; Buck, Wayne; Cohen, Nicholas; Marr, Shauna; Gantress, Jennifer

2005-01-01

Xenopus has been used as an experimental model to evaluate the contribution of adaptive cellular immunity in amphibian host susceptibility to the emerging ranavirus FV3. Conventional histology and immunohistochemistry reveal that FV3 has a strong tropism for the proximal tubular epithelium of the kidney and is rarely disseminated elsewhere in Xenopus hosts unless their immune defenses are impaired or developmentally immature as in larvae. In such cases, virus is found widespread in most tissues. Adults, immunocompromised by depletion of CD8 + T cells or by sub-lethal γ-irradiation, show increased susceptibility to FV3 infection. Larvae and irradiated (but not normal) adults can be cross-infected through water by infected adult conspecifics (irradiated or not). The natural MHC class I deficiency and the absence of effect of anti-CD8 treatment on both larval CD8 + T cells and larval susceptibility to FV3 are consistent with an inefficient CD8 + T cell effector function during this developmental period

Dehydration triggers differential microRNA expression in Xenopus laevis brain.

Science.gov (United States)

Luu, Bryan E; Storey, Kenneth B

2015-11-15

African clawed frogs, Xenopus laevis, although primarily aquatic, have a high tolerance for dehydration, being capable of withstanding the loss of up to 32-35% of total water body water. Recent studies have shown that microRNAs play a role in the response to dehydration by the liver, kidney and ventral skin of X. laevis. MicroRNAs act by modulating the expression of mRNA transcripts, thereby affecting diverse biochemical pathways. In this study, 43 microRNAs were assessed in frog brains comparing control and dehydrated (31.2±0.83% of total body water lost) conditions. MicroRNAs of interest were measured using a modified protocol which employs polyadenylation of microRNAs prior to reverse transcription and qPCR. Twelve microRNAs that showed a significant decrease in expression (to 41-77% of control levels) in brains from dehydrated frogs (xla-miR-15a, -150, -181a, -191, -211, -218, -219b, -30c, -30e, -31, -34a, and -34b) were identified. Genomic analysis showed that the sequences of these dehydration-responsive microRNAs were highly conserved as compared with the comparable microRNAs of mice (91-100%). Suppression of these microRNAs implies that translation of the mRNA transcripts under their control could be enhanced in response to dehydration. Bioinformatic analysis using the DIANA miRPath program (v.2.0) predicted the top two KEGG pathways that these microRNAs collectively regulate: 1. Axon guidance, and 2. Long-term potentiation. Previous studies indicated that suppression of these microRNAs promotes neuroprotective pathways by increasing the expression of brain-derived neurotrophic factor and activating anti-apoptotic pathways. This suggests that similar actions may be triggered in X. laevis brains as a protective response to dehydration. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

Macro and Trace Element Accumulation in Edible Crabs and Frogs ...

African Journals Online (AJOL)

The tissue accumulation of five macroelements (Na, Mg, K, Ca, Fe) and twelve trace elements (Vd, Mn, Co, Ni, Cu, Zn, As, Se, Mo, Ag, Cd, Pb) were assessed in the organs of the edible frogs; Xenopus laevis and Rana esculentus, and whole body of the crab, Callinestes caught from Alaro Stream Floodplain (Ibadan, ...

Formation of cell masses in the myelencephalon of the clawed frog ...

African Journals Online (AJOL)

An important process in the organization of developing nervous system is the clustering of neurons with similar properties to form nuclei. The development of myelencephalon of Xenopus muelleri, a pipid frog that retains a lateral line system throughout life, was studied in Nissl stained serial sections. The results showed that ...

DDT exposure of frogs: A case study from Limpopo Province, South Africa.

Science.gov (United States)

Viljoen, Ignatius M; Bornman, Riana; Bouwman, Hindrik

2016-09-01

Amphibians are globally under pressure with environmental contaminants contributing to this. Despite caution aired more than 80 years ago of threats posed to amphibians by DDT spraying for disease vector control, no data have been published on concentrations or effects of DDT contamination in frogs from areas where DDT is actively sprayed to control the insect vectors of malaria. In this study, we sampled fat bodies of Xenopus laevis and Xenopus muelleri naturally occurring in an area where indoor residual spraying of DDT is employed and from adjacent, non-sprayed, areas. ΣDDT concentrations ranged between DDT in the eggs of the Grey Heron Ardea cinerea. This suggests that the DDT we found in frogs may have contributed to DDT loadings higher in the food web. These findings, combined with other studies from this area, support the need to reduce and eventually move away from DDT in malaria control safely and sustainably. Copyright © 2016 Elsevier Ltd. All rights reserved.

The right thalamus may play an important role in anesthesia-awakening regulation in frogs

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Yanzhu Fan

2018-03-01

Full Text Available Background Previous studies have shown that the mammalian thalamus is a key structure for anesthesia-induced unconsciousness and anesthesia-awakening regulation. However, both the dynamic characteristics and probable lateralization of thalamic functioning during anesthesia-awakening regulation are not fully understood, and little is known of the evolutionary basis of the role of the thalamus in anesthesia-awakening regulation. Methods An amphibian species, the South African clawed frog (Xenopus laevis was used in the present study. The frogs were immersed in triciane methanesulfonate (MS-222 for general anesthesia. Electroencephalogram (EEG signals were recorded continuously from both sides of the telencephalon, diencephalon (thalamus and mesencephalon during the pre-anesthesia stage, administration stage, recovery stage and post-anesthesia stage. EEG data was analyzed including calculation of approximate entropy (ApEn and permutation entropy (PE. Results Both ApEn and PE values differed significantly between anesthesia stages, with the highest values occurring during the awakening period and the lowest values during the anesthesia period. There was a significant correlation between the stage durations and ApEn or PE values during anesthesia-awakening cycle primarily for the right diencephalon (right thalamus. ApEn and PE values for females were significantly higher than those for males. Discussion ApEn and PE measurements are suitable for estimating depth of anesthesia and complexity of amphibian brain activity. The right thalamus appears physiologically positioned to play an important role in anesthesia-awakening regulation in frogs indicating an early evolutionary origin of the role of the thalamus in arousal and consciousness in land vertebrates. Sex differences exist in the neural regulation of general anesthesia in frogs.

A Novel Amphibian Tier 2 Testing Protocol: A 30-Week Exposure of Xenopus Tropicalis to the Antiandrogen Flutamide

National Research Council Canada - National Science Library

Knechtges, Paul L; Sprando, Robert L; Porter, Karen L; Brennan, Linda M; Miller, Mark F; Kumsher, David M; Dennis, William E; Brown, Charles C; Clegg Paul L. Knechtges. Robert L. Sprando. Karen L. Potter., Eric D

2007-01-01

.... For that reason, a tier 2 testing protocol using Xenopus (Silurana) tropicalis and a 30-week, flow-through exposure to the antiandrogen flutamide from stage 46 tadpoles through sexually mature adult frogs were developed and evaluated in this pilot study...

Life in the spray zone – overlooked diversity in West African torrent-frogs (Anura, Odontobatrachidae, Odontobatrachus

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Michael Barej

2015-07-01

Full Text Available West African torrent-frogs of the genus Odontobatrachus currently belong to a single species: Odontobatrachus natator (Boulenger, 1905. Recently, molecular results and biogeographic separation led to the recognition of five Operational Taxonomic Units (OTUs thus identifying a species-complex. Based on these insights, morphological analyses on more than 150 adult specimens, covering the entire distribution of the family and all OTUs, were carried out. Despite strong morphological congruence, combinations of morphological characters made the differentiation of OTUs successful and allowed the recognition of five distinct species: Odontobatrachus natator, and four species new to science: Odontobatrachus arndti sp. n., O. fouta sp. n., O. smithi sp. n. and O. ziama sp. n. All species occur in parapatry: Odontobatrachus natator is known from western Guinea to eastern Liberia, O. ziama sp. n. from eastern Guinea, O. smithi sp. n. and O. fouta sp. n. from western Guinea, O. arndti sp. n. from the border triangle Guinea-Liberia-Côte d’Ivoire. In addition, for the first time the advertisement call of a West African torrent-frog (O. arndti sp. n. is described.

Combining Cytotoxicity Assessment and Xenopus laevis Phenotypic Abnormality Assay as a Predictor of Nanomaterial Safety.

Science.gov (United States)

Al-Yousuf, Karamallah; Webster, Carl A; Wheeler, Grant N; Bombelli, Francesca Baldelli; Sherwood, Victoria

2017-08-04

The African clawed frog, Xenopus laevis, has been used as an efficient pre-clinical screening tool to predict drug safety during the early stages of the drug discovery process. X. laevis is a relatively inexpensive model that can be used in whole organism high-throughput assays whilst maintaining a high degree of homology to the higher vertebrate models often used in scientific research. Despite an ever-increasing volume of biomedical nanoparticles (NPs) in development, their unique physico-chemical properties challenge the use of standard toxicology assays. Here, we present a protocol that directly compares the sensitivity of X. laevis development as a tool to assess potential NP toxicity by observation of embryo phenotypic abnormalities/lethality after NP exposure, to in vitro cytotoxicity obtained using mammalian cell lines. In combination with conventional cytotoxicity assays, the X. laevis phenotypic assay provides accurate data to efficiently assess the safety of novel biomedical NPs. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 by John Wiley & Sons, Inc.

High-Magnification In Vivo Imaging of Xenopus Embryos for Cell and Developmental Biology

OpenAIRE

sprotocols

2014-01-01

Authors: Esther K. Kieserman, Chanjae Lee, Ryan S. Gray, Tae Joo Park and John B. Wallingford Corresponding author ([]()). ### INTRODUCTION Embryos of the frog *Xenopus laevis* are an ideal model system for in vivo imaging of dynamic biological processes, from the inner workings of individual cells to the reshaping of tissues during embryogenesis. Their externally developing embryos are more amenable to in vivo analysis than in...

Identification, synthesis and mass spectrometry of a macrolide from the African reed frog Hyperolius cinnamomeoventris

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Markus Menke

2016-12-01

Full Text Available The contents of the gular glands of the male African reed frog Hyperolius cinnamomeoventris consist of a mixture of aliphatic macrolides and sesquiterpenes. While the known macrolide gephyromantolide A was readily identified, the structure of another major component was suggested to be a tetradecen-13-olide. The synthesis of the two candidate compounds (Z-5- and (Z-9-tetradecen-13-olide revealed the former to be the naturally occurring compound. The synthesis used ring-closing metathesis as key step. While the Hoveyda–Grubbs catalyst furnished a broad range of isomeric products, the (Z-selective Grubbs catalyst lead to pure (Z-products. Analysis by chiral GC revealed the natural frog compound to be (5Z,13S-5-tetradecen-13-olide (1. This compound is also present in the secretion of other hyperoliid frogs as well as in femoral glands of male mantellid frogs such as Spinomantis aglavei. The mass spectra of the synthesized macrolides as well as their rearranged isomers obtained during ring-closing metathesis showed that it is possible to assign the location of the double bond in an unsaturated macrolide on the basis of its EI mass spectrum. The occurrence of characteristic ions can be explained by the fragmentation pathway proposed in the article. In contrast, the localization of a double bond in many aliphatic open-chain compounds like alkenes, alcohols or acetates, important structural classes of pheromones, is usually not possible from an EI mass spectrum. In the article, we present the synthesis and for the first time elucidate the structure of macrolides from the frog family Hyperoliidae.

Evidence from peptidomic analysis of skin secretions that allopatric populations of Xenopus gilli (Anura:Pipidae) constitute distinct lineages.

Science.gov (United States)

Conlon, J Michael; Mechkarska, Milena; Coquet, Laurent; Leprince, Jérôme; Jouenne, Thierry; Vaudry, Hubert; Measey, G John

2015-01-01

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-precursor fragment (XPF) peptides, nine caerulein-precursor fragment (CPF) peptides, and a peptide related to peptide glycine-glutamine (PGQ) previously found in an extract of Xenopus laevis stomach. The primary structures of the peptides indicate a close phylogenetic relationship between X. gilli and X. laevis but only magainin-1, PGLa and one CPF peptide are identical in both species. Consistent with previous data, the CPF peptides show the greatest antimicrobial potency but are hemolytic. There are appreciable differences in the expression of host-defense peptide genes in frogs from the population of animals sampled near Kleinmond as peptides corresponding to magainin-G2, XPF-G1, XPF-G2, and four CPF peptides, present in secretions from the Cape Peninsula frogs, were not identified in the skin secretions from Kleinmond frogs. Conversely, PGLa-G3, XPF-G3, and three CPF peptides were identified in the Kleinmond frogs but not in the Cape Peninsula animals. The data support the conclusion from morphometric analyses and comparisons of the nucleotide sequences of mitochondrial genes that the disjunct populations of X. gilli have undergone appreciable genetic, morphological, and phenotypic divergence. Copyright © 2014 Elsevier Inc. All rights reserved.

Remobilization of Sleeping Beauty transposons in the germline of Xenopus tropicalis

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Yergeau Donald A

2011-11-01

Full Text Available Abstract Background The Sleeping Beauty (SB transposon system has been used for germline transgenesis of the diploid frog, Xenopus tropicalis. Injecting one-cell embryos with plasmid DNA harboring an SB transposon substrate together with mRNA encoding the SB transposase enzyme resulted in non-canonical integration of small-order concatemers of the transposon. Here, we demonstrate that SB transposons stably integrated into the frog genome are effective substrates for remobilization. Results Transgenic frogs that express the SB10 transposase were bred with SB transposon-harboring animals to yield double-transgenic 'hopper' frogs. Remobilization events were observed in the progeny of the hopper frogs and were verified by Southern blot analysis and cloning of the novel integrations sites. Unlike the co-injection method used to generate founder lines, transgenic remobilization resulted in canonical transposition of the SB transposons. The remobilized SB transposons frequently integrated near the site of the donor locus; approximately 80% re-integrated with 3 Mb of the donor locus, a phenomenon known as 'local hopping'. Conclusions In this study, we demonstrate that SB transposons integrated into the X. tropicalis genome are effective substrates for excision and re-integration, and that the remobilized transposons are transmitted through the germline. This is an important step in the development of large-scale transposon-mediated gene- and enhancer-trap strategies in this highly tractable developmental model system.

Life Histories of Frogs in the Namib Desert | Channing | African ...

African Journals Online (AJOL)

Four anuran taxa inhabit the central Namib: Xenopus laevis, Tomopterna delalandei cryptotis, Phrynomerus annectens and Bufo vertebrate hoeschi. Xenopus is confined to permanent pools in the Kuiseb river canyon. Tomopterna extends further into the Namib, but is restricted to the Kuiseb river bed. The Kuiseb is normally ...

Distribution of BDE-99 and effects on metamorphosis of BDE-99 and -47 after oral exposure in Xenopus tropicalis

Energy Technology Data Exchange (ETDEWEB)

Carlsson, Gunnar [Division of Pathology, Pharmacology and Toxicology, Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, P.O. Box 7028, SE-750 07 Uppsala (Sweden) and Centre for Reproductive Biology in Uppsala (CRU), P.O. Box 7054, SE-750 07 Uppsala (Sweden)]. E-mail: gunnar.carlsson@bvf.slu.se; Kulkarni, Pushkar [Division of Pathology, Pharmacology and Toxicology, Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, P.O. Box 7028, SE-750 07 Uppsala (Sweden); Larsson, Pia [Division of Pathology, Pharmacology and Toxicology, Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, P.O. Box 7028, SE-750 07 Uppsala (Sweden); Norrgren, Leif [Division of Pathology, Pharmacology and Toxicology, Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, P.O. Box 7028, SE-750 07 Uppsala (Sweden); Centre for Reproductive Biology in Uppsala (CRU), P.O. Box 7054, SE-750 07 Uppsala (Sweden)

2007-08-15

The high concentrations of polybrominated diphenylethers (PBDEs) in the environment have raised the need for generating more information about the impact of these substances on animals. To study the distribution of {sup 14}C-labelled 2,2',4,4',5-pentabromodiphenyl ether ({sup 14}C-BDE-99) in Xenopus tropicalis (West African clawed frog) {sup 14}C-BDE-99 was administered by dietary exposure to tadpoles at stage 54 or to juvenile frogs at stage 66. Whole-body autoradiography and liquid scintillation counting were used to examine the distribution of the substance at different survival times. Further, X. tropicalis tadpoles were dietarily exposed to the PBDE congeners BDE-47 and BDE-99 to study the effects on metamorphosis process. Measurements like body weight, body length, hind limb length and developmental stage as well as histological measurements on thyroid glands were performed after 14 days of exposure. Autoradiograms revealed high concentrations and long term retention of {sup 14}C-BDE-99 in adipose tissue and melanin in frogs exposed both as tadpoles and juveniles. Further, a difference in uptake was recorded between the exposures at stages 54 and 66, implying that the juvenile frogs have higher uptake and more prolonged retention of the chemical than the tadpoles. Hind limb length was reduced in tadpoles dietarily exposed to 1 mg/g feed of both BDE congeners. This was associated with reduced body weight and body length for BDE-47, suggesting general toxicity. Tadpoles exposed to BDE-99 also showed lower developmental stage but no effects on body weight or body length, suggesting possible thyroid hormone disruption. Higher concentrations of both congeners caused increased mortality. Thus, it can be concluded that in the present study, BDE-99 was retained for a longer period in the juvenile frogs than in metamorphosing tadpoles and that BDE-99 had an impact on X. tropicalis metamorphosis that might be of thyroid disrupting origin.

Distribution of BDE-99 and effects on metamorphosis of BDE-99 and -47 after oral exposure in Xenopus tropicalis

International Nuclear Information System (INIS)

Carlsson, Gunnar; Kulkarni, Pushkar; Larsson, Pia; Norrgren, Leif

2007-01-01

The high concentrations of polybrominated diphenylethers (PBDEs) in the environment have raised the need for generating more information about the impact of these substances on animals. To study the distribution of 14 C-labelled 2,2',4,4',5-pentabromodiphenyl ether ( 14 C-BDE-99) in Xenopus tropicalis (West African clawed frog) 14 C-BDE-99 was administered by dietary exposure to tadpoles at stage 54 or to juvenile frogs at stage 66. Whole-body autoradiography and liquid scintillation counting were used to examine the distribution of the substance at different survival times. Further, X. tropicalis tadpoles were dietarily exposed to the PBDE congeners BDE-47 and BDE-99 to study the effects on metamorphosis process. Measurements like body weight, body length, hind limb length and developmental stage as well as histological measurements on thyroid glands were performed after 14 days of exposure. Autoradiograms revealed high concentrations and long term retention of 14 C-BDE-99 in adipose tissue and melanin in frogs exposed both as tadpoles and juveniles. Further, a difference in uptake was recorded between the exposures at stages 54 and 66, implying that the juvenile frogs have higher uptake and more prolonged retention of the chemical than the tadpoles. Hind limb length was reduced in tadpoles dietarily exposed to 1 mg/g feed of both BDE congeners. This was associated with reduced body weight and body length for BDE-47, suggesting general toxicity. Tadpoles exposed to BDE-99 also showed lower developmental stage but no effects on body weight or body length, suggesting possible thyroid hormone disruption. Higher concentrations of both congeners caused increased mortality. Thus, it can be concluded that in the present study, BDE-99 was retained for a longer period in the juvenile frogs than in metamorphosing tadpoles and that BDE-99 had an impact on X. tropicalis metamorphosis that might be of thyroid disrupting origin

Genetics, morphology, advertisement calls, and historical records distinguish six new polyploid species of African clawed frog (Xenopus, Pipidae) from West and Central Africa

Czech Academy of Sciences Publication Activity Database

Evans, B. J.; Carter, T. F.; Greenbaum, E.; Gvoždík, Václav; Kelley, D. B.; McLaughlin, P. J.; Pauwels, O. S. G.; Portik, D. M.; Stanley, E. L.; Tinsley, R. C.; Tobias, M. L.; Blackburn, D. C.

2015-01-01

Roč. 10, č. 12 (2015), č. článku e0142823. E-ISSN 1932-6203 R&D Projects: GA ČR GJ15-13415Y Institutional support: RVO:68081766 Keywords : host-defense peptides * genus Xenopus * skin secretions * South Africa * evolutionary relationships * model organism Subject RIV: EG - Zoology Impact factor: 3.057, year: 2015

Polystyrene nanoparticles affect Xenopus laevis development

Energy Technology Data Exchange (ETDEWEB)

Tussellino, Margherita; Ronca, Raffaele [University of Naples Federico II, Department of Biology (Italy); Formiggini, Fabio [Italian Institute of Technology, Center for Advanced Biomaterials for Health Care IIT@CRIB (Italy); Marco, Nadia De [University of Naples Federico II, Department of Biology (Italy); Fusco, Sabato; Netti, Paolo Antonio [Italian Institute of Technology, Center for Advanced Biomaterials for Health Care IIT@CRIB (Italy); Carotenuto, Rosa, E-mail: rosa.carotenuto@unina.it [University of Naples Federico II, Department of Biology (Italy)

2015-02-15

Exposing living organisms to nanoparticulates is potentially hazardous, in particular when it takes place during embryogenesis. In this investigation, we have studied the effects of 50-nm-uncoated polystyrene nanoparticles (PSNPs) as a model to investigate the suitability of their possible future employments. We have used the standardized Frog Embryo Teratogenesis Assay-Xenopus test during the early stages of larval development of Xenopus laevis, and we have employed either contact exposure or microinjections. We found that the embryos mortality rate is dose dependent and that the survived embryos showed high percentage of malformations. They display disorders in pigmentation distribution, malformations of the head, gut and tail, edema in the anterior ventral region, and a shorter body length compared with sibling untreated embryos. Moreover, these embryos grow more slowly than the untreated embryos. Expressions of the mesoderm markers, bra (T-box Brachyury gene), myod1 (myogenic differentiation1), and of neural crest marker sox9 (sex SRY (determining region Y-box 9) transcription factor sox9), are modified. Confocal microscopy showed that the nanoparticles are localized in the cytoplasm, in the nucleus, and in the periphery of the digestive gut cells. Our data suggest that PSNPs are toxic and show a potential teratogenic effect for Xenopus larvae. We hypothesize that these effects may be due either to the amount of NPs that penetrate into the cells and/or to the “corona” effect caused by the interaction of PSNPs with cytoplasm components. The three endpoints of our study, i.e., mortality, malformations, and growth inhibition, suggest that the tests we used may be a powerful and flexible bioassay in evaluating pollutants in aquatic embryos.

Polystyrene nanoparticles affect Xenopus laevis development

International Nuclear Information System (INIS)

Tussellino, Margherita; Ronca, Raffaele; Formiggini, Fabio; Marco, Nadia De; Fusco, Sabato; Netti, Paolo Antonio; Carotenuto, Rosa

2015-01-01

Exposing living organisms to nanoparticulates is potentially hazardous, in particular when it takes place during embryogenesis. In this investigation, we have studied the effects of 50-nm-uncoated polystyrene nanoparticles (PSNPs) as a model to investigate the suitability of their possible future employments. We have used the standardized Frog Embryo Teratogenesis Assay-Xenopus test during the early stages of larval development of Xenopus laevis, and we have employed either contact exposure or microinjections. We found that the embryos mortality rate is dose dependent and that the survived embryos showed high percentage of malformations. They display disorders in pigmentation distribution, malformations of the head, gut and tail, edema in the anterior ventral region, and a shorter body length compared with sibling untreated embryos. Moreover, these embryos grow more slowly than the untreated embryos. Expressions of the mesoderm markers, bra (T-box Brachyury gene), myod1 (myogenic differentiation1), and of neural crest marker sox9 (sex SRY (determining region Y-box 9) transcription factor sox9), are modified. Confocal microscopy showed that the nanoparticles are localized in the cytoplasm, in the nucleus, and in the periphery of the digestive gut cells. Our data suggest that PSNPs are toxic and show a potential teratogenic effect for Xenopus larvae. We hypothesize that these effects may be due either to the amount of NPs that penetrate into the cells and/or to the “corona” effect caused by the interaction of PSNPs with cytoplasm components. The three endpoints of our study, i.e., mortality, malformations, and growth inhibition, suggest that the tests we used may be a powerful and flexible bioassay in evaluating pollutants in aquatic embryos

Evaluation of developmental toxicity and teratogenicity of diclofenac using Xenopus embryos.

Science.gov (United States)

Chae, Jeong-Pil; Park, Mi Seon; Hwang, Yoo-Seok; Min, Byung-Hwa; Kim, Sang-Hyun; Lee, Hyun-Shik; Park, Mae-Ja

2015-02-01

Diclofenac is a non-steroidal anti-inflammatory drug (NSAID) with analgesic and anti-pyretic properties. This compound is therefore used to treat pain, inflammatory disorders, and dysmenorrhea. Due to its multimodal mechanism of action and ability to penetrate placenta, diclofenac is known to have undesirable side effects including teratogenicity. However, limited data exist on its teratogenicity, and a detailed investigation regarding harmful effects of this drug during embryogenesis is warranted. Here, we analyzed the developmental toxic effects of diclofenac using Xenopus embryos according to the Frog Embryo Teratogenesis Assay-Xenopus (FETAX) protocol. Diclofenac treatment exerted a teratogenic effect on Xenopus embryos with a teratogenic index (TI) value of 2.64 TI; if this value is higher than 1.2, the cut-off value indicative of toxicity. In particular, mortality of embryos treated with diclofenac increased in a concentration-dependent manner and a broad spectrum of malformations such as shortening and kinking of the axis, abdominal bulging, and prominent blister formation, was observed. The shape and length of internal organs also differed compared to the control group embryos and show developmental retardation on histological label. However, the expression of major tissue-specific markers did not change when analyzed by reverse transcription-polymerase chain reaction (RT-PCR). In conclusion, diclofenac treatment can promote teratogenicity that results in morphological anomalies, but not disrupt the developmental tissue arrangement during Xenopus embryogenesis. Copyright © 2014 Elsevier Ltd. All rights reserved.

Fishing on chips: up-and-coming technological advances in analysis of zebrafish and Xenopus embryos.

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Zhu, Feng; Skommer, Joanna; Huang, Yushi; Akagi, Jin; Adams, Dany; Levin, Michael; Hall, Chris J; Crosier, Philip S; Wlodkowic, Donald

2014-11-01

Biotests performed on small vertebrate model organisms provide significant investigative advantages as compared with bioassays that employ cell lines, isolated primary cells, or tissue samples. The main advantage offered by whole-organism approaches is that the effects under study occur in the context of intact physiological milieu, with all its intercellular and multisystem interactions. The gap between the high-throughput cell-based in vitro assays and low-throughput, disproportionally expensive and ethically controversial mammal in vivo tests can be closed by small model organisms such as zebrafish or Xenopus. The optical transparency of their tissues, the ease of genetic manipulation and straightforward husbandry, explain the growing popularity of these model organisms. Nevertheless, despite the potential for miniaturization, automation and subsequent increase in throughput of experimental setups, the manipulation, dispensing and analysis of living fish and frog embryos remain labor-intensive. Recently, a new generation of miniaturized chip-based devices have been developed for zebrafish and Xenopus embryo on-chip culture and experimentation. In this work, we review the critical developments in the field of Lab-on-a-Chip devices designed to alleviate the limits of traditional platforms for studies on zebrafish and clawed frog embryo and larvae. © 2014 International Society for Advancement of Cytometry. © 2014 International Society for Advancement of Cytometry.

Skin wound healing in different aged Xenopus laevis.

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Bertolotti, Evelina; Malagoli, Davide; Franchini, Antonella

2013-08-01

Xenopus froglets can perfectly heal skin wounds without scarring. To explore whether this capacity is maintained as development proceeds, we examined the cellular responses during the repair of skin injury in 8- and 15-month-old Xenopus laevis. The morphology and sequence of healing phases (i.e., inflammation, new tissue formation, and remodeling) were independent of age, while the timing was delayed in older frogs. At the beginning of postinjury, wound re-epithelialization occurred in form of a thin epithelium followed by a multilayered epidermis containing cells with apoptotic patterns and keratinocytes stained by anti-inducible nitric oxide synthase (iNOS) antibody. The inflammatory response, early activated by recruitment of blood cells immunoreactive to anti-tumor necrosis factor (TNF)-α, iNOS, transforming growth factor (TGF)-β1, and matrix metalloproteinase (MMP)-9, persisted over time. The dermis repaired by a granulation tissue with extensive angiogenesis, inflammatory cells, fibroblasts, and anti-α-SMA positive myofibroblasts. As the healing progressed, wounded areas displayed vascular regression, decrease in cellularity, and rearrangement of provisional matrix. The epidermis restored to a prewound morphology while granulation tissue was replaced by a fibrous tissue in a scar-like pattern. The quantitative PCR analysis demonstrated an up-regulated expression of Xenopus suppressor of cytokine signaling 3 (XSOCS-3) and Xenopus transforming growth factor-β2 (XTGF-β2) soon after wounding and peak levels were detected when granulation tissue was well developed with a large number of inflammatory cells. The findings indicate that X. laevis skin wound healing occurred by a combination of regeneration (in epidermis) and repair (in dermis) and, in contrast to froglet scarless wound healing, the growth to a more mature adult stage is associated with a decrease in regenerative capacity with scar-like tissue formation. Copyright © 2013 Wiley Periodicals, Inc.

Plasma concentrations of estradiol and testosterone, gonadal aromatase activity and ultrastructure of the testis in Xenopus laevis exposed to estradiol or atrazine

International Nuclear Information System (INIS)

Hecker, Markus; Kim, Wan Jong; Park, June-Woo; Murphy, Margaret B.; Villeneuve, Daniel; Coady, Katherine K.; Jones, Paul D.; Solomon, Keith R.; Kraak, Glen van der; Carr, James A.; Smith, Ernest E.; Preez, Louis du; Kendall, Ronald J.; Giesy, John P.

2005-01-01

The ultrastructure of testicular cells of adult male African clawed frogs (Xenopus laevis) exposed to either estradiol (0.1 μg/L) or 2-chloro-4-ethylamino-6-isopropyl-amino-s-triazine (atrazine; 10 or 100 μg/L) was examined by electron microscopy and compared to plasma concentrations of the steroid hormones, testosterone (T) and estradiol (E2), testicular aromatase activity and gonad growth expressed as the gonado-somatic index (GSI). Exposure to E2 caused significant changes both at the sub-cellular and biochemical levels. Exposure to E2 resulted in significantly fewer sperm cells, inhibition of meiotic division of germ cells, more lipid droplets that are storage compartments for the sex steroid hormone precursor cholesterol, and lesser plasma T concentrations. Although not statistically significant, frogs exposed to E2 had slightly smaller GSI values. These results may be indicative of an inhibition of gonad growth and disrupted germ cell development by E2. Concentrations of E2 in plasma were greater in frogs exposed to E2 in water. Exposure to neither concentration of atrazine caused effects on germ cell development, testicular aromatase activity or plasma hormone concentrations. These results suggest that atrazine does not affect testicular function. In contrast, exposure of male X. laevis to E2 led to sub-cellular events that are indicative of disruption of testicular development, and demasculinization processes (decrease of androgen hormone titers). These results indicate that atrazine does not cause responses that are similar to those caused by exposure to E2

Characterization of Cer-1 cis-regulatory region during early Xenopus development.

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Silva, Ana Cristina; Filipe, Mário; Steinbeisser, Herbert; Belo, José António

2011-05-01

Cerberus-related molecules are well-known Wnt, Nodal, and BMP inhibitors that have been implicated in different processes including anterior–posterior patterning and left–right asymmetry. In both mouse and frog, two Cerberus-related genes have been isolated, mCer-1 and mCer-2, and Xcer and Xcoco, respectively. Until now, little is known about the mechanisms involved in their transcriptional regulation. Here, we report a heterologous analysis of the mouse Cerberus-1 gene upstream regulatory regions, responsible for its expression in the visceral endodermal cells. Our analysis showed that the consensus sequences for a TATA, CAAT, or GC boxes were absent but a TGTGG sequence was present at position -172 to -168 bp, relative to the ATG. Using a series of deletion constructs and transient expression in Xenopus embryos, we found that a fragment of 1.4 kb of Cer-1 promoter sequence could reproduce the endogenous expression pattern of Xenopus cerberus. A 0.7-kb mcer-1 upstream region was able to drive reporter expression to the involuting mesendodermal cells, while further deletions abolished reporter gene expression. Our results suggest that although no sequence similarity was found between mouse and Xenopus cerberus cis-regulatory regions, the signaling cascades regulating cerberus expression, during gastrulation, is conserved.

Metabolic cost of osmoregulation in a hypertonic environment in the invasive African clawed frog Xenopus laevis

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Isaac Peña-Villalobos

2016-07-01

Full Text Available Studies of aquatic invertebrates reveal that salinity affects feeding and growth rates, reproduction, survival, and diversity. Little is known, however, about how salinity impacts the energy budget of vertebrates and amphibians in particular. The few studies focused on this topic in vertebrates suggest that the ingestion of salts and the resulting osmoregulatory activity is energetically expensive. We analyzed the effect of saline acclimation on standard metabolic rates (SMR and the activities of metabolic enzymes of internal organs and osmoregulatory variables (plasma osmolality and urea plasma level in females of Xenopus laevis by means of acclimating individuals to an isosmotic (235 mOsm NaCl; ISO group and hyper-osmotic (340 mOsm NaCl; HYP group environment for 40 days. After acclimation, we found that total and mass-specific SMR was approximately 80% higher in the HYP group than those found in the ISO group. These changes were accompanied by higher citrate synthase activities in liver and heart in the HYP group than in the ISO group. Furthermore, we found a significant and positive correlation between metabolic rates and plasma urea, and citrate synthase activity in liver and heart. These results support the notion that the cost of osmoregulation is probably common in most animal species and suggest the existence of a functional association between metabolic rates and the adjustments in osmoregulatory physiology, such as blood distribution and urea synthesis.

Dramatic Declines of Montane Frogs in a Central African Biodiversity Hotspot

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Hirschfeld, Mareike; Blackburn, David C.; Doherty-Bone, Thomas M.; Gonwouo, LeGrand Nono; Ghose, Sonia; Rödel, Mark-Oliver

2016-01-01

Amphibian populations are vanishing worldwide. Declines and extinctions of many populations have been attributed to chytridiomycosis, a disease induced by the pathogenic fungus Batrachochytrium dendrobatidis (Bd). In Africa, however, changes in amphibian assemblages were typically attributed to habitat change. We conducted a retrospective study utilizing field surveys from 2004–2012 of the anuran faunas on two mountains in western Cameroon, a hotspot of African amphibian diversity. The number of species detected was negatively influenced by year, habitat degradation, and elevation, and we detected a decline of certain species. Because another study in this region revealed an emergence of Bd in 2008, we screened additional recent field-collected samples and also pre-decline preserved museum specimens for the presence of Bd supporting emergence before 2008. When comparing the years before and after Bd detection, we found significantly diminished frog species richness and abundance on both mountains after Bd emergence. Our analyses suggest that this may be the first disease-driven community-level decline in anuran biodiversity in Central Africa. The disappearance of several species known to tolerate habitat degradation, and a trend of stronger declines at higher elevations, are consistent with Bd-induced declines in other regions. Not all species decreased; populations of some species remained constant, and others increased after the emergence of Bd. This variation might be explained by species-specific differences in infection probability. Increased habitat protection and Bd-mitigation strategies are needed for sustaining diverse amphibian communities such as those on Mt. Manengouba, which contains nearly half of Cameroon’s frog diversity. PMID:27149624

Dramatic Declines of Montane Frogs in a Central African Biodiversity Hotspot.

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Mareike Hirschfeld

Full Text Available Amphibian populations are vanishing worldwide. Declines and extinctions of many populations have been attributed to chytridiomycosis, a disease induced by the pathogenic fungus Batrachochytrium dendrobatidis (Bd. In Africa, however, changes in amphibian assemblages were typically attributed to habitat change. We conducted a retrospective study utilizing field surveys from 2004-2012 of the anuran faunas on two mountains in western Cameroon, a hotspot of African amphibian diversity. The number of species detected was negatively influenced by year, habitat degradation, and elevation, and we detected a decline of certain species. Because another study in this region revealed an emergence of Bd in 2008, we screened additional recent field-collected samples and also pre-decline preserved museum specimens for the presence of Bd supporting emergence before 2008. When comparing the years before and after Bd detection, we found significantly diminished frog species richness and abundance on both mountains after Bd emergence. Our analyses suggest that this may be the first disease-driven community-level decline in anuran biodiversity in Central Africa. The disappearance of several species known to tolerate habitat degradation, and a trend of stronger declines at higher elevations, are consistent with Bd-induced declines in other regions. Not all species decreased; populations of some species remained constant, and others increased after the emergence of Bd. This variation might be explained by species-specific differences in infection probability. Increased habitat protection and Bd-mitigation strategies are needed for sustaining diverse amphibian communities such as those on Mt. Manengouba, which contains nearly half of Cameroon's frog diversity.

Musashi and Plasticity of Xenopus and Axolotl Spinal Cord Ependymal Cells

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Chernoff, Ellen A. G.; Sato, Kazuna; Salfity, Hai V. N.; Sarria, Deborah A.; Belecky-Adams, Teri

2018-01-01

The differentiated state of spinal cord ependymal cells in regeneration-competent amphibians varies between a constitutively active state in what is essentially a developing organism, the tadpole of the frog Xenopus laevis, and a quiescent, activatable state in a slowly growing adult salamander Ambystoma mexicanum, the Axolotl. Ependymal cells are epithelial in intact spinal cord of all vertebrates. After transection, body region ependymal epithelium in both Xenopus and the Axolotl disorganizes for regenerative outgrowth (gap replacement). Injury-reactive ependymal cells serve as a stem/progenitor cell population in regeneration and reconstruct the central canal. Expression patterns of mRNA and protein for the stem/progenitor cell-maintenance Notch signaling pathway mRNA-binding protein Musashi (msi) change with life stage and regeneration competence. Msi-1 is missing (immunohistochemistry), or at very low levels (polymerase chain reaction, PCR), in both intact regeneration-competent adult Axolotl cord and intact non-regeneration-competent Xenopus tadpole (Nieuwkoop and Faber stage 62+, NF 62+). The critical correlation for successful regeneration is msi-1 expression/upregulation after injury in the ependymal outgrowth and stump-region ependymal cells. msi-1 and msi-2 isoforms were cloned for the Axolotl as well as previously unknown isoforms of Xenopus msi-2. Intact Xenopus spinal cord ependymal cells show a loss of msi-1 expression between regeneration-competent (NF 50–53) and non-regenerating stages (NF 62+) and in post-metamorphosis froglets, while msi-2 displays a lower molecular weight isoform in non-regenerating cord. In the Axolotl, embryos and juveniles maintain Msi-1 expression in the intact cord. In the adult Axolotl, Msi-1 is absent, but upregulates after injury. Msi-2 levels are more variable among Axolotl life stages: rising between late tailbud embryos and juveniles and decreasing in adult cord. Cultures of regeneration-competent Xenopus tadpole

Musashi and Plasticity of Xenopus and Axolotl Spinal Cord Ependymal Cells

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Ellen A. G. Chernoff

2018-02-01

Full Text Available The differentiated state of spinal cord ependymal cells in regeneration-competent amphibians varies between a constitutively active state in what is essentially a developing organism, the tadpole of the frog Xenopus laevis, and a quiescent, activatable state in a slowly growing adult salamander Ambystoma mexicanum, the Axolotl. Ependymal cells are epithelial in intact spinal cord of all vertebrates. After transection, body region ependymal epithelium in both Xenopus and the Axolotl disorganizes for regenerative outgrowth (gap replacement. Injury-reactive ependymal cells serve as a stem/progenitor cell population in regeneration and reconstruct the central canal. Expression patterns of mRNA and protein for the stem/progenitor cell-maintenance Notch signaling pathway mRNA-binding protein Musashi (msi change with life stage and regeneration competence. Msi-1 is missing (immunohistochemistry, or at very low levels (polymerase chain reaction, PCR, in both intact regeneration-competent adult Axolotl cord and intact non-regeneration-competent Xenopus tadpole (Nieuwkoop and Faber stage 62+, NF 62+. The critical correlation for successful regeneration is msi-1 expression/upregulation after injury in the ependymal outgrowth and stump-region ependymal cells. msi-1 and msi-2 isoforms were cloned for the Axolotl as well as previously unknown isoforms of Xenopus msi-2. Intact Xenopus spinal cord ependymal cells show a loss of msi-1 expression between regeneration-competent (NF 50–53 and non-regenerating stages (NF 62+ and in post-metamorphosis froglets, while msi-2 displays a lower molecular weight isoform in non-regenerating cord. In the Axolotl, embryos and juveniles maintain Msi-1 expression in the intact cord. In the adult Axolotl, Msi-1 is absent, but upregulates after injury. Msi-2 levels are more variable among Axolotl life stages: rising between late tailbud embryos and juveniles and decreasing in adult cord. Cultures of regeneration

Mesoderm layer formation in Xenopus and Drosophila gastrulation

International Nuclear Information System (INIS)

Winklbauer, Rudolf; Müller, H-Arno J

2011-01-01

During gastrulation, the mesoderm spreads out between ectoderm and endoderm to form a mesenchymal cell layer. Surprisingly the underlying principles of mesoderm layer formation are very similar in evolutionarily distant species like the fruit fly, Drosophila melanogaster, and the frog, Xenopus laevis, in which the molecular and the cellular basis of mesoderm layer formation have been extensively studied. Complementary expression of growth factors in the ectoderm and their receptors in the mesoderm act to orient cellular protrusive activities and direct cell movement, leading to radial cell intercalation and the spreading of the mesoderm layer. This mechanism is contrasted with generic physical mechanisms of tissue spreading that consider the adhesive and physical properties of the cells and tissues. Both mechanisms need to be integrated to orchestrate mesenchymal morphogenesis

De novo Transcriptome Assemblies of Rana (Lithobates catesbeiana and Xenopus laevis Tadpole Livers for Comparative Genomics without Reference Genomes.

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Inanc Birol

Full Text Available 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 treatment/control pairs. We de novo assembled these reads using Trans-ABySS to reconstruct reference transcriptomes, obtaining over 350,000 and 130,000 putative transcripts for R. catesbeiana and X. laevis, respectively. Using available genomics resources for X. laevis, we annotated over 97% of our X. laevis transcriptome contigs, demonstrating the utility and efficacy of our methodology. Leveraging this validated analysis pipeline, we also annotated the assembled R. catesbeiana transcriptome. We used the expression profiles of the annotated genes of the two species to examine the similarities and differences between the tadpole liver transcriptomes. We also compared the gene ontology terms of expressed genes to measure how the animals react to a challenge by thyroid hormone. Our study reports three main conclusions. First, de novo assembly of RNA-seq data is a powerful method for annotating and establishing transcriptomes of non-model organisms. Second, the liver transcriptomes of the two frog species, R. catesbeiana and X. laevis, show many common features, and the distribution of their gene ontology profiles are statistically indistinguishable. Third, although they broadly respond the same way to the presence of thyroid hormone in their environment, their receptor/signal transduction pathways display marked differences.

The extraordinary biology and development of marsupial frogs (Hemiphractidae) in comparison with fish, mammals, birds, amphibians and other animals.

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Del Pino, Eugenia M

2018-01-03

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 Gastrotheca riobambae (Hemiphractidae) and the embryonic development of this frog are summarized. Moreover, G. riobambae gastrulation is compared with the gastrulation modes of Engystomops randi and Engystomops coloradorum (Leptodactylidae); Ceratophrys stolzmanni (Ceratophryidae); Hyalinobatrachium fleischmanni and Espadarana callistomma (Centrolenidae); Ameerega bilinguis, Dendrobates auratus, Epipedobates anthonyi, Epipedobates machalilla, Epipedobates tricolor, and Hyloxalus vertebralis (Dendrobatidae); Eleutherodactylus coqui (Terrarana: Eleutherodactylidae), and X. laevis (Pipidae). The comparison indicated two modes of frog gastrulation. In X. laevis and in frogs with aquatic reproduction, convergent extension begins during gastrulation. In contrast, convergent extension occurs in the post-gastrula of frogs with terrestrial reproduction. These two modes of gastrulation resemble the transitions toward meroblastic cleavage found in ray-finned fishes (Actinopterygii). In spite of this difference, the genes that guide early development seem to be highly conserved in frogs. I conclude that the shift of convergent extension to the post-gastrula accompanied the diversification of frog egg size and terrestrial reproductive modes. Copyright © 2018 Elsevier B.V. All rights reserved.

Xenopus-FV3 host-pathogen interactions and immune evasion.

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Jacques, Robert; Edholm, Eva-Stina; Jazz, Sanchez; Odalys, Torres-Luquis; Francisco, De Jesús Andino

2017-11-01

We first review fundamental insights into anti-ranavirus immunity learned with the Xenopus laevis/ranavirus FV3 model that are generally applicable to ectothermic vertebrates. We then further investigate FV3 genes involved in immune evasion. Focusing on FV3 knockout (KO) mutants defective for a putative viral caspase activation and recruitment domain-containing (CARD)-like protein (Δ64R-FV3), a β-hydroxysteroid dehydrogenase homolog (Δ52L-FV3), and an immediate-early18kDa protein (FV3-Δ18K), we assessed the involvement of these viral genes in replication, dissemination and interaction with peritoneal macrophages in tadpole and adult frogs. Our results substantiate the role of 64R and 52L as critical immune evasion genes, promoting persistence and dissemination in the host by counteracting type III IFN in tadpoles and type I IFN in adult frogs. Comparably, the substantial accumulation of genome copy numbers and exacerbation of type I and III IFN gene expression responses but deficient release of infectious virus suggests that 18K is a viral regulatory gene. Copyright © 2017 Elsevier Inc. All rights reserved.

Further Development and Validation of the Frog Embryo Teratogenesis Assay - Xenopus (FETAX). Phase III

National Research Council Canada - National Science Library

Bantle, John

1996-01-01

This interlaboratory study of the Frog Embryo Teratogenesis Assay (FETAX) was undertaken in order to assess the repeatability and reliability of data collected under the guide published by the American Society for Testing and Materials...

Early Pliocene anuran fossils from Kanapoi, Kenya, and the first fossil record for the African burrowing frog Hemisus (Neobatrachia: Hemisotidae).

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Delfino, Massimo

2017-07-13

Isolated amphibian bones from the early Pliocene of Kanapoi (West Turkana, Kenya) help to improve the scarce fossil record of the late Neogene and Quaternary amphibians from East Africa. All currently available 579 bones are referable exclusively to the Anura (frogs and toads). More than half of the remains (366) are identified as Hemisus cf. Hemisus marmoratus, an extant species that still inhabits Kenya, but apparently not the northwest of the country and the Turkana area in particular. The rest of the remains are identified simply as Anura indet. because of poor preservation or non congruence with the relatively few African extant taxa whose osteology is known in detail. The Hemisus material represents the first fossil record for Hemisotidae, an endemic African family of peculiar, head-first burrowing frogs, whose sister taxon relationships indicate a divergence from brevicipitids in the Late Cretaceous or early Paleocene. The ecological requirements of extant H. marmoratus suggest that the Kanapoi area surrounding the fluvial and deltaic settings, from where the fossil remains of vertebrates were buried, was likely a grassland or relatively dry, open low tree-shrub savanna. Copyright © 2017 Elsevier Ltd. All rights reserved.

Sex chromosome differentiation and the W- and Z-specific loci in Xenopus laevis.

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Mawaribuchi, Shuuji; Takahashi, Shuji; Wada, Mikako; Uno, Yoshinobu; Matsuda, Yoichi; Kondo, Mariko; Fukui, Akimasa; Takamatsu, Nobuhiko; Taira, Masanori; Ito, Michihiko

2017-06-15

Genetic sex-determining systems in vertebrates include two basic types of heterogamety; XX (female)/XY (male) and ZZ (male)/ZW (female) types. The African clawed frog Xenopus laevis has a ZZ/ZW-type sex-determining system. In this species, we previously identified a W-specific sex (female)-determining gene dmw, and specified W and Z chromosomes, which could be morphologically indistinguishable (homomorphic). In addition to dmw, we most recently discovered two genes, named scanw and ccdc69w, and one gene, named capn5z in the W- and Z-specific regions, respectively. In this study, we revealed the detail structures of the W/Z-specific loci and genes. Sequence analysis indicated that there is almost no sequence similarity between 278kb W-specific and 83kb Z-specific sequences on chromosome 2Lq32-33, where both the transposable elements are abundant. Synteny and phylogenic analyses indicated that all the W/Z-specific genes might have emerged independently. Expression analysis demonstrated that scanw and ccdc69w or capn5z are expressed in early differentiating ZW gonads or testes, thereby suggesting possible roles in female or male development, respectively. Importantly, the sex-determining gene (SDG) dmw might have been generated after allotetraploidization, thereby indicating the construction of the new sex-determining system by dmw after species hybridization. Furthermore, by direct genotyping, we confirmed that diploid WW embryos developed into normal female frogs, which indicate that the Z-specific region is not essential for female development. Overall, these findings indicate that sex chromosome differentiation has started, although no heteromorphic sex chromosomes are evident yet, in X. laevis. Homologous recombination suppression might have promoted the accumulation of mutations and transposable elements, and enlarged the W/Z-specific regions, thereby resulting in differentiation of the W/Z chromosomes. Copyright © 2016 Elsevier Inc. All rights reserved.

Exploring nervous system transcriptomes during embryogenesis and metamorphosis in Xenopus tropicalis using EST analysis

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Wegnez Maurice

2007-05-01

Full Text Available Abstract Background The western African clawed frog Xenopus tropicalis is an anuran amphibian species now used as model in vertebrate comparative genomics. It provides the same advantages as Xenopus laevis but is diploid and has a smaller genome of 1.7 Gbp. Therefore X. tropicalis is more amenable to systematic transcriptome surveys. We initiated a large-scale partial cDNA sequencing project to provide a functional genomics resource on genes expressed in the nervous system during early embryogenesis and metamorphosis in X. tropicalis. Results A gene index was defined and analysed after the collection of over 48,785 high quality sequences. These partial cDNA sequences were obtained from an embryonic head and retina library (30,272 sequences and from a metamorphic brain and spinal cord library (27,602 sequences. These ESTs are estimated to represent 9,693 transcripts derived from an estimated 6,000 genes. Comparison of these cDNA sequences with protein databases indicates that 46% contain their start codon. Further annotation included Gene Ontology functional classification, InterPro domain analysis, alternative splicing and non-coding RNA identification. Gene expression profiles were derived from EST counts and used to define transcripts specific to metamorphic stages of development. Moreover, these ESTs allowed identification of a set of 225 polymorphic microsatellites that can be used as genetic markers. Conclusion These cDNA sequences permit in silico cloning of numerous genes and will facilitate studies aimed at deciphering the roles of cognate genes expressed in the nervous system during neural development and metamorphosis. The genomic resources developed to study X. tropicalis biology will accelerate exploration of amphibian physiology and genetics. In particular, the model will facilitate analysis of key questions related to anuran embryogenesis and metamorphosis and its associated regulatory processes.

Chromosome Banding in Amphibia. XXXII. The Genus Xenopus (Anura, Pipidae).

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Schmid, Michael; Steinlein, Claus

2015-01-01

Mitotic chromosomes of 16 species of the frog genus Xenopus were prepared from kidney and lung cell cultures. In the chromosomes of 7 species, high-resolution replication banding patterns could be induced by treating the cultures with 5-bromodeoxyuridine (BrdU) and deoxythymidine (dT) in succession, and in 6 of these species the BrdU/dT-banded chromosomes could be arranged into karyotypes. In the 3 species of the clade with 2n = 20 and 4n = 40 chromosomes (X. tropicalis, X. epitropicalis, X. new tetraploid 1), as well as in the 3 species with 4n = 36 chromosomes (X. laevis, X. borealis, X. muelleri), the BrdU/dT-banded karyotypes show a high degree of homoeology, though differences were detected between these groups. Translocations, inversions, insertions or sex-specific replication bands were not observed. Minor replication asynchronies found between chromosomes probably involve heterochromatic regions. BrdU/dT replication banding of Xenopus chromosomes provides the landmarks necessary for the exact physical mapping of genes and repetitive sequences. FISH with an X. laevis 5S rDNA probe detected multiple hybridization sites at or near the long-arm telomeric regions in most chromosomes of X. laevis and X. borealis, whereas in X. muelleri, the 5S rDNA sequences are located exclusively at the long-arm telomeres of a single chromosome pair. Staining with the AT base pair-specific fluorochrome quinacrine mustard revealed brightly fluorescing heterochromatic regions in the majority of X. borealis chromosomes which are absent in other Xenopus species.

Regulation of ALF promoter activity in Xenopus oocytes.

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Dan Li

Full Text Available BACKGROUND: In this report we evaluate the use of Xenopus laevis oocytes as a matched germ cell system for characterizing the organization and transcriptional activity of a germ cell-specific X. laevis promoter. PRINCIPAL FINDINGS: The promoter from the ALF transcription factor gene was cloned from X. laevis genomic DNA using a PCR-based genomic walking approach. The endogenous ALF gene was characterized by RACE and RT-PCR for transcription start site usage, and by sodium bisulfite sequencing to determine its methylation status in somatic and oocyte tissues. Homology between the X. laevis ALF promoter sequence and those from human, chimpanzee, macaque, mouse, rat, cow, pig, horse, dog, chicken and X. tropicalis was relatively low, making it difficult to use such comparisons to identify putative regulatory elements. However, microinjected promoter constructs were very active in oocytes and the minimal promoter could be narrowed by PCR-mediated deletion to a region as short as 63 base pairs. Additional experiments using a series of site-specific promoter mutants identified two cis-elements within the 63 base pair minimal promoter that were critical for activity. Both elements (A and B were specifically recognized by proteins present in crude oocyte extracts based on oligonucleotide competition assays. The activity of promoter constructs in oocytes and in transfected somatic Xenopus XLK-WG kidney epithelial cells was quite different, indicating that the two cell types are not functionally equivalent and are not interchangeable as assay systems. CONCLUSIONS: Overall the results provide the first detailed characterization of the organization of a germ cell-specific Xenopus promoter and demonstrate the feasibility of using immature frog oocytes as an assay system for dissecting the biochemistry of germ cell gene regulation.

Significant modulation of the hepatic proteome induced by exposure to low temperature in Xenopus laevis

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Kazumichi Nagasawa

2013-08-01

The African clawed frog, Xenopus laevis, is an ectothermic vertebrate that can survive at low environmental temperatures. To gain insight into the molecular events induced by low body temperature, liver proteins were evaluated at the standard laboratory rearing temperature (22°C, control and a low environmental temperature (5°C, cold exposure. Using nano-flow liquid chromatography coupled with tandem mass spectrometry, we identified 58 proteins that differed in abundance. A subsequent Gene Ontology analysis revealed that the tyrosine and phenylalanine catabolic processes were modulated by cold exposure, which resulted in decreases in hepatic tyrosine and phenylalanine, respectively. Similarly, levels of pyruvate kinase and enolase, which are involved in glycolysis and glycogen synthesis, were also decreased, whereas levels of glycogen phosphorylase, which participates in glycogenolysis, were increased. Therefore, we measured metabolites in the respective pathways and found that levels of hepatic glycogen and glucose were decreased. Although the liver was under oxidative stress because of iron accumulation caused by hepatic erythrocyte destruction, the hepatic NADPH/NADP ratio was not changed. Thus, glycogen is probably utilized mainly for NADPH supply rather than for energy or glucose production. In conclusion, X. laevis responds to low body temperature by modulating its hepatic proteome, which results in altered carbohydrate metabolism.

Next generation sequencing and comparative analyses of Xenopus mitogenomes

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Lloyd Rhiannon E

2012-09-01

Full Text Available Abstract Background Mitochondrial genomes comprise a small but critical component of the total DNA in eukaryotic organisms. They encode several key proteins for the cell’s major energy producing apparatus, the mitochondrial respiratory chain. Additonally, their nucleotide and amino acid sequences are of great utility as markers for systematics, molecular ecology and forensics. Their characterization through nucleotide sequencing is a fundamental starting point in mitogenomics. Methods to amplify complete mitochondrial genomes rapidly and efficiently from microgram quantities of tissue of single individuals are, however, not always available. Here we validate two approaches, which combine long-PCR with Roche 454 pyrosequencing technology, to obtain two complete mitochondrial genomes from individual amphibian species. Results We obtained two new xenopus frogs (Xenopus borealis and X. victorianus complete mitochondrial genome sequences by means of long-PCR followed by 454 of individual genomes (approach 1 or of multiple pooled genomes (approach 2, the mean depth of coverage per nucleotide was 9823 and 186, respectively. We also characterised and compared the new mitogenomes against their sister taxa; X. laevis and Silurana tropicalis, two of the most intensely studied amphibians. Our results demonstrate how our approaches can be used to obtain complete amphibian mitogenomes with depths of coverage that far surpass traditional primer-walking strategies, at either the same cost or less. Our results also demonstrate: that the size, gene content and order are the same among xenopus mitogenomes and that S. tropicalis form a separate clade to the other xenopus, among which X. laevis and X. victorianus were most closely related. Nucleotide and amino acid diversity was found to vary across the xenopus mitogenomes, with the greatest diversity observed in the Complex 1 gene nad4l and the least diversity observed in Complex 4 genes (cox1-3. All protein

Fertilization and development of eggs of the South African clawed toad, Xenopus laevis, on sounding rockets in space.

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Ubbels, G A; Berendsen, W; Kerkvliet, S; Narraway, J

1992-01-01

Egg rotation and centrifugation experiments strongly suggest a role for gravity in the determination of the spatial structure of amphibian embryos. Decisive experiments can only be made in Space. Eggs of Xenopus laevis, the South African clawed toad, were the first vertebrate eggs which were successfully fertilized on Sounding Rockets in Space. Unfixed, newly fertilized eggs survived reentry, and a reasonable number showed a seemingly normal gastrulation but died between gastrulation and neurulation. Only a few reached the larval stage, but these developed abnormally. In the future, we intend to test whether this abnormal morphogenesis is due to reentry perturbations, or due to a real microgravity effect, through perturbation of the reinitiation of meiosis and other processes, or started by later sperm penetration.

Vestibular lesion-induced developmental plasticity in spinal locomotor networks during Xenopus laevis metamorphosis.

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Beyeler, Anna; Rao, Guillaume; Ladepeche, Laurent; Jacques, André; Simmers, John; Le Ray, Didier

2013-01-01

During frog metamorphosis, the vestibular sensory system remains unchanged, while spinal motor networks undergo a massive restructuring associated with the transition from the larval to adult biomechanical system. We investigated in Xenopus laevis the impact of a pre- (tadpole stage) or post-metamorphosis (juvenile stage) unilateral labyrinthectomy (UL) on young adult swimming performance and underlying spinal locomotor circuitry. The acute disruptive effects on locomotion were similar in both tadpoles and juvenile frogs. However, animals that had metamorphosed with a preceding UL expressed restored swimming behavior at the juvenile stage, whereas animals lesioned after metamorphosis never recovered. Whilst kinematic and electrophysiological analyses of the propulsive system showed no significant differences in either juvenile group, a 3D biomechanical simulation suggested that an asymmetry in the dynamic control of posture during swimming could account for the behavioral restoration observed in animals that had been labyrinthectomized before metamorphosis. This hypothesis was subsequently supported by in vivo electromyography during free swimming and in vitro recordings from isolated brainstem/spinal cord preparations. Specifically, animals lesioned prior to metamorphosis at the larval stage exhibited an asymmetrical propulsion/posture coupling as a post-metamorphic young adult. This developmental alteration was accompanied by an ipsilesional decrease in propriospinal coordination that is normally established in strict left-right symmetry during metamorphosis in order to synchronize dorsal trunk muscle contractions with bilateral hindlimb extensions in the swimming adult. Our data thus suggest that a disequilibrium in descending vestibulospinal information during Xenopus metamorphosis leads to an altered assembly of adult spinal locomotor circuitry. This in turn enables an adaptive compensation for the dynamic postural asymmetry induced by the vestibular imbalance

Frog eat frog: exploring variables influencing anurophagy

OpenAIRE

Measey, G. John; Vimercati, Giovanni; de Villiers, F. Andr?; Mokhatla, Mohlamatsane M.; Davies, Sarah J.; Edwards, Shelley; Altwegg, Res

2015-01-01

Background. Frogs are generalist predators of a wide range of typically small prey items. But descriptions of dietary items regularly include other anurans, such that frogs are considered to be among the most important of anuran predators. However, the only existing hypothesis for the inclusion of anurans in the diet of post-metamorphic frogs postulates that it happens more often in bigger frogs. Moreover, this hypothesis has yet to be tested. Methods. We reviewed the literature on frog diet ...

Effects of cadmium, estradiol-17beta and their interaction on gonadal condition and metamorphosis of male and female African clawed frog, Xenopus laevis

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Sharma, Bibek; Patino, Reynaldo

2010-01-01

To assess interaction effects between cadmium (Cd, a putative xenoestrogen) and estradiol-17beta (E(2)) on sex differentiation and metamorphosis, Xenopus laevis were exposed to solvent-control (0.005% ethanol), Cd (10microgL(-1)), E(2) (1microgL(-1)), or Cd and E(2) (Cd+E(2)) in FETAX medium from fertilization to 75d postfertilization. Each treatment was applied to four aquaria, each with 30 fertilized eggs. Mortality was recorded and animals were sampled as they completed metamorphosis (Nieuwkoop and Faber stage 66). Gonadal sex of individuals (including >or= tadpoles NF stage 55 at day 75) was determined gross-morphologically and used to compute sex ratios. Time course and percent completion of metamorphosis, snout-vent length (SVL), hindlimb length (HLL) and weight were analyzed for each gender separately. Survival rates did not differ among treatments. The E(2) and Cd+E(2) treatments significantly skewed sex ratios towards females; however, no sex-ratio differences were observed between the control and Cd treatments or between the E(2) and Cd+E(2) treatments. Time course of metamorphosis was generally delayed and percent completion of metamorphosis was generally reduced in males and females exposed to Cd, E(2) or their combination compared to control animals. In males, but not females, the effect of Cd+E(2) was greater than that of individual chemicals. Weight at completion of metamorphosis was reduced only in females and only by the Cd+E(2) treatment. In conclusion, although Cd at an environmentally relevant concentration did not exhibit direct or indirect feminizing effects in Xenopus tadpoles, the metal and E(2) both had similar inhibitory effects on metamorphosis that were of greater magnitude in males than females.

Effects of cadmium, estradiol-17β and their interaction on gonadal condition and metamorphosis of male and female African clawed frog, Xenopus laevis

Science.gov (United States)

Sharma, Bibek; Patino, Reynaldo

2010-01-01

To assess interaction effects between cadmium (Cd, a putative xenoestrogen) and estradiol-17?? (E2) on sex differentiation and metamorphosis, Xenopus laevis were exposed to solvent-control (0.005% ethanol), Cd (10 ??g L-1), E2 (1 ??g L-1), or Cd and E2 (Cd + E2) in FETAX medium from fertilization to 75 d postfertilization. Each treatment was applied to four aquaria, each with 30 fertilized eggs. Mortality was recorded and animals were sampled as they completed metamorphosis (Nieuwkoop and Faber stage 66). Gonadal sex of individuals (including tadpoles ???NF stage 55 at day 75) was determined gross-morphologically and used to compute sex ratios. Time course and percent completion of metamorphosis, snout-vent length (SVL), hindlimb length (HLL) and weight were analyzed for each gender separately. Survival rates did not differ among treatments. The E2 and Cd + E2 treatments significantly skewed sex ratios towards females; however, no sex-ratio differences were observed between the control and Cd treatments or between the E2 and Cd + E2 treatments. Time course of metamorphosis was generally delayed and percent completion of metamorphosis was generally reduced in males and females exposed to Cd, E2 or their combination compared to control animals. In males, but not females, the effect of Cd + E2 was greater than that of individual chemicals. Weight at completion of metamorphosis was reduced only in females and only by the Cd + E2 treatment. In conclusion, although Cd at an environmentally relevant concentration did not exhibit direct or indirect feminizing effects in Xenopus tadpoles, the metal and E2 both had similar inhibitory effects on metamorphosis that were of greater magnitude in males than females.

Frog eat frog: exploring variables influencing anurophagy.

Science.gov (United States)

Measey, G John; Vimercati, Giovanni; de Villiers, F André; Mokhatla, Mohlamatsane M; Davies, Sarah J; Edwards, Shelley; Altwegg, Res

2015-01-01

Background. Frogs are generalist predators of a wide range of typically small prey items. But descriptions of dietary items regularly include other anurans, such that frogs are considered to be among the most important of anuran predators. However, the only existing hypothesis for the inclusion of anurans in the diet of post-metamorphic frogs postulates that it happens more often in bigger frogs. Moreover, this hypothesis has yet to be tested. Methods. We reviewed the literature on frog diet in order to test the size hypothesis and determine whether there are other putative explanations for anurans in the diet of post-metamorphic frogs. In addition to size, we recorded the habitat, the number of other sympatric anuran species, and whether or not the population was invasive. We controlled for taxonomic bias by including the superfamily in our analysis. Results. Around one fifth of the 355 records included anurans as dietary items of populations studied, suggesting that frogs eating anurans is not unusual. Our data showed a clear taxonomic bias with ranids and pipids having a higher proportion of anuran prey than other superfamilies. Accounting for this taxonomic bias, we found that size in addition to being invasive, local anuran diversity, and habitat produced a model that best fitted our data. Large invasive frogs that live in forests with high anuran diversity are most likely to have a higher proportion of anurans in their diet. Conclusions. We confirm the validity of the size hypothesis for anurophagy, but show that there are additional significant variables. The circumstances under which frogs eat frogs are likely to be complex, but our data may help to alert conservationists to the possible dangers of invading frogs entering areas with threatened anuran species.

Frog eat frog: exploring variables influencing anurophagy

Directory of Open Access Journals (Sweden)

G. John Measey

2015-08-01

Full Text Available Background. Frogs are generalist predators of a wide range of typically small prey items. But descriptions of dietary items regularly include other anurans, such that frogs are considered to be among the most important of anuran predators. However, the only existing hypothesis for the inclusion of anurans in the diet of post-metamorphic frogs postulates that it happens more often in bigger frogs. Moreover, this hypothesis has yet to be tested.Methods. We reviewed the literature on frog diet in order to test the size hypothesis and determine whether there are other putative explanations for anurans in the diet of post-metamorphic frogs. In addition to size, we recorded the habitat, the number of other sympatric anuran species, and whether or not the population was invasive. We controlled for taxonomic bias by including the superfamily in our analysis.Results. Around one fifth of the 355 records included anurans as dietary items of populations studied, suggesting that frogs eating anurans is not unusual. Our data showed a clear taxonomic bias with ranids and pipids having a higher proportion of anuran prey than other superfamilies. Accounting for this taxonomic bias, we found that size in addition to being invasive, local anuran diversity, and habitat produced a model that best fitted our data. Large invasive frogs that live in forests with high anuran diversity are most likely to have a higher proportion of anurans in their diet.Conclusions. We confirm the validity of the size hypothesis for anurophagy, but show that there are additional significant variables. The circumstances under which frogs eat frogs are likely to be complex, but our data may help to alert conservationists to the possible dangers of invading frogs entering areas with threatened anuran species.

Vectorcardiogram of the 'Man-Frog' | Skowron | South African ...

African Journals Online (AJOL)

Chest electrodes from a man and from a frog are connected simultaneously to an oscilloscope - the one to the vertical and the other to the horizontal plates - and the resulting display observed. It consists of a loop, the interpretation of which is discussed, and the conclusion is reached that the presently held vector theory ...

Phylogeny, Functional Annotation, and Protein Interaction Network Analyses of the Xenopus tropicalis Basic Helix-Loop-Helix Transcription Factors

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Wuyi Liu

2013-01-01

Full Text Available The previous survey identified 70 basic helix-loop-helix (bHLH proteins, but it was proved to be incomplete, and the functional information and regulatory networks of frog bHLH transcription factors were not fully known. Therefore, we conducted an updated genome-wide survey in the Xenopus tropicalis genome project databases and identified 105 bHLH sequences. Among the retrieved 105 sequences, phylogenetic analyses revealed that 103 bHLH proteins belonged to 43 families or subfamilies with 46, 26, 11, 3, 15, and 4 members in the corresponding supergroups. Next, gene ontology (GO enrichment analyses showed 65 significant GO annotations of biological processes and molecular functions and KEGG pathways counted in frequency. To explore the functional pathways, regulatory gene networks, and/or related gene groups coding for Xenopus tropicalis bHLH proteins, the identified bHLH genes were put into the databases KOBAS and STRING to get the signaling information of pathways and protein interaction networks according to available public databases and known protein interactions. From the genome annotation and pathway analysis using KOBAS, we identified 16 pathways in the Xenopus tropicalis genome. From the STRING interaction analysis, 68 hub proteins were identified, and many hub proteins created a tight network or a functional module within the protein families.

A new grass frog from Namibia | Channing | African Zoology

African Journals Online (AJOL)

A new species of grass frog of lhe genus Ptychadena is described from northern Namibia. Although superficially similar to Ptychadena schillukorum and Ptychadena mossambica, the new species differs In advertisement call, and external characters. An examination of a series of published sonagrams indicates that ...

Thyrotropin-releasing hormone (TRH promotes wound re-epithelialisation in frog and human skin.

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Natalia T Meier

Full Text Available There remains a critical need for new therapeutics that promote wound healing in patients suffering from chronic skin wounds. This is, in part, due to a shortage of simple, physiologically and clinically relevant test systems for investigating candidate agents. The skin of amphibians possesses a remarkable regenerative capacity, which remains insufficiently explored for clinical purposes. Combining comparative biology with a translational medicine approach, we report the development and application of a simple ex vivo frog (Xenopus tropicalis skin organ culture system that permits exploration of the effects of amphibian skin-derived agents on re-epithelialisation in both frog and human skin. Using this amphibian model, we identify thyrotropin-releasing hormone (TRH as a novel stimulant of epidermal regeneration. Moving to a complementary human ex vivo wounded skin assay, we demonstrate that the effects of TRH are conserved across the amphibian-mammalian divide: TRH stimulates wound closure and formation of neo-epidermis in organ-cultured human skin, accompanied by increased keratinocyte proliferation and wound healing-associated differentiation (cytokeratin 6 expression. Thus, TRH represents a novel, clinically relevant neuroendocrine wound repair promoter that deserves further exploration. These complementary frog and human skin ex vivo assays encourage a comparative biology approach in future wound healing research so as to facilitate the rapid identification and preclinical testing of novel, evolutionarily conserved, and clinically relevant wound healing promoters.

Thyrotropin-Releasing Hormone (TRH) Promotes Wound Re-Epithelialisation in Frog and Human Skin

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Zhang, Guo-You; Emelianov, Vladimir; Paredes, Roberto; Debus, Sebastian; Augustin, Matthias; Funk, Wolfgang; Amaya, Enrique; Kloepper, Jennifer E.; Hardman, Matthew J.; Paus, Ralf

2013-01-01

There remains a critical need for new therapeutics that promote wound healing in patients suffering from chronic skin wounds. This is, in part, due to a shortage of simple, physiologically and clinically relevant test systems for investigating candidate agents. The skin of amphibians possesses a remarkable regenerative capacity, which remains insufficiently explored for clinical purposes. Combining comparative biology with a translational medicine approach, we report the development and application of a simple ex vivo frog (Xenopus tropicalis) skin organ culture system that permits exploration of the effects of amphibian skin-derived agents on re-epithelialisation in both frog and human skin. Using this amphibian model, we identify thyrotropin-releasing hormone (TRH) as a novel stimulant of epidermal regeneration. Moving to a complementary human ex vivo wounded skin assay, we demonstrate that the effects of TRH are conserved across the amphibian-mammalian divide: TRH stimulates wound closure and formation of neo-epidermis in organ-cultured human skin, accompanied by increased keratinocyte proliferation and wound healing-associated differentiation (cytokeratin 6 expression). Thus, TRH represents a novel, clinically relevant neuroendocrine wound repair promoter that deserves further exploration. These complementary frog and human skin ex vivo assays encourage a comparative biology approach in future wound healing research so as to facilitate the rapid identification and preclinical testing of novel, evolutionarily conserved, and clinically relevant wound healing promoters. PMID:24023889

Compendium of the FY1990 and FY1992 Research Reviews for the Research Methods Branch

Science.gov (United States)

1994-09-01

fish digestion. In: Cultivation of Fish Fry and Its Live Food, E. Styczynska-Jurewicz, T. Backiel, E. Japers, and G. Persoone, eds. Bredene, Belgium...sunfish exposed to contaminated sediment. Ecotoxicology , in press. Van Holde, K.E. (ed.) 1989. Chromatin. New York: Springer-Verlag. 136 ORNITHINE...developmental toxicity test that utilizes the embryos of the South African clawed frog Xenopus laevis. The assay has applications for ecotoxicology and also

Comparative studies of the endonucleases from two related Xenopus laevis retrotransposons, Tx1L and Tx2L: target site specificity and evolutionary implications.

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Christensen, S; Pont-Kingdon, G; Carroll, D

2000-01-01

In the genome of the South African frog, Xenopus laevis, there are two complex families of transposable elements, Tx1 and Tx2, that have identical overall structures, but distinct sequences. In each family there are approximately 1500 copies of an apparent DNA-based element (Tx1D and Tx2D). Roughly 10% of these elements in each family are interrupted by a non-LTR retrotransposon (Tx1L and Tx2L). Each retrotransposon is flanked by a 23-bp target duplication of a specific D element sequence. In earlier work, we showed that the endonuclease domain (Tx1L EN) located in the second open reading frame (ORF2) of Tx1L encodes a protein that makes a single-strand cut precisely at the expected site within its target sequence, supporting the idea that Tx1L is a site-specific retrotransposon. In this study, we express the endonuclease domain of Tx2L (Tx2L EN) and compare the target preferences of the two enzymes. Each endonuclease shows some preference for its cognate target, on the order of 5-fold over the non-cognate target. The observed discrimination is not sufficient, however, to explain the observation that no cross-occupancy is observed - that is, L elements of one family have never been found within D elements of the other family. Possible sources of additional specificity are discussed. We also compare two hypotheses regarding the genome duplication event that led to the contemporary pseudotetraploid character of Xenopus laevis in light of the Tx1L and Tx2L data.

Genome-wide transcriptional response of Silurana (Xenopus tropicalis to infection with the deadly chytrid fungus.

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Erica Bree Rosenblum

Full Text Available Emerging infectious diseases are of great concern for both wildlife and humans. Several highly virulent fungal pathogens have recently been discovered in natural populations, highlighting the need for a better understanding of fungal-vertebrate host-pathogen interactions. Because most fungal pathogens are not fatal in the absence of other predisposing conditions, host-pathogen dynamics for deadly fungal pathogens are of particular interest. The chytrid fungus Batrachochytrium dendrobatidis (hereafter Bd infects hundreds of species of frogs in the wild. It is found worldwide and is a significant contributor to the current global amphibian decline. However, the mechanism by which Bd causes death in amphibians, and the response of the host to Bd infection, remain largely unknown. Here we use whole-genome microarrays to monitor the transcriptional responses to Bd infection in the model frog species, Silurana (Xenopus tropicalis, which is susceptible to chytridiomycosis. To elucidate the immune response to Bd and evaluate the physiological effects of chytridiomycosis, we measured gene expression changes in several tissues (liver, skin, spleen following exposure to Bd. We detected a strong transcriptional response for genes involved in physiological processes that can help explain some clinical symptoms of chytridiomycosis at the organismal level. However, we detected surprisingly little evidence of an immune response to Bd exposure, suggesting that this susceptible species may not be mounting efficient innate and adaptive immune responses against Bd. The weak immune response may be partially explained by the thermal conditions of the experiment, which were optimal for Bd growth. However, many immune genes exhibited decreased expression in Bd-exposed frogs compared to control frogs, suggesting a more complex effect of Bd on the immune system than simple temperature-mediated immune suppression. This study generates important baseline data for ongoing

Chemical camouflage--a frog's strategy to co-exist with aggressive ants.

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Mark-Oliver Rödel

Full Text Available Whereas interspecific associations receive considerable attention in evolutionary, behavioural and ecological literature, the proximate bases for these associations are usually unknown. This in particular applies to associations between vertebrates with invertebrates. The West-African savanna frog Phrynomantis microps lives in the underground nest of ponerine ants (Paltothyreus tarsatus. The ants usually react highly aggressively when disturbed by fiercely stinging, but the frog is not attacked and lives unharmed among the ants. Herein we examined the proximate mechanisms for this unusual association. Experiments with termites and mealworms covered with the skin secretion of the frog revealed that specific chemical compounds seem to prevent the ants from stinging. By HPLC-fractionation of an aqueous solution of the frogs' skin secretion, two peptides of 1,029 and 1,143 Da were isolated and found to inhibit the aggressive behaviour of the ants. By de novo sequencing using tandem mass spectrometry, the amino acid sequence of both peptides consisting of a chain of 9 and 11 residues, respectively, was elucidated. Both peptides were synthesized and tested, and exhibited the same inhibitory properties as the original frog secretions. These novel peptides most likely act as an appeasement allomone and may serve as models for taming insect aggression.

Ecological Risk Assessment of Perchlorate in Avian Species, Rodents, Amphibians and Fish

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2008-08-01

nutritional physiology. Vet. Res. Commun. 8:77–91. Lee S-Y, Brodman BW. 2004. Biodegradation of 1,3,5-trinitro-1,3,5-triazine (RDX). Journal of...laevis (African clawed frog) Strain: Outbred Age: embryo/Larvae/Adults Source: All of Xenopus used in this proposal were bred from captive stocks...Laboratory studies have shown that PAHs may stimulate the induction of hepatic monooxygenase activity in birds , although PAHs are rapidly metabolized, and

Effects of Transgenic cry1Ca Rice on the Development of Xenopus laevis.

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Xiuping Chen

Full Text Available In fields of genetically modified, insect-resistant rice expressing Bacillus thuringiensis (Bt proteins, frogs are exposed to Bt Cry proteins by consuming both target and non-target insects, and through their highly permeable skin. In the present study, we assessed the potential risk posed by transgenic cry1Ca rice (T1C-19 on the development of a frog species by adding purified Cry1Ca protein or T1C-19 rice straw into the rearing water of Xenopus laevis tadpoles, and by feeding X. laevis froglets diets containing rice grains of T1C-19 or its non-transformed counterpart MH63. Our results showed that there were no significant differences among groups receiving 100 μg L-1 or 10 μg L-1 Cry1Ca and the blank control in terms of time to completed metamorphosis, survival rate, body weight, body length, organ weight and liver enzyme activity after being exposed to the Cry1Ca (P > 0.05. Although some detection indices in the rice straw groups were significantly different from those of the blank control group (P < 0.05, there was no significant difference between the T1C-19 and MH63 rice straw groups. Moreover, there were no significant differences in the mortality rate, body weight, daily weight gain, liver and fat body weight of the froglets between the T1C-19 and MH63 dietary groups after 90 days, and there were no abnormal pathological changes in the stomach, intestines, livers, spleens and gonads. Thus, we conclude that the planting of transgenic cry1Ca rice will not adversely affect frog development.

Effects of agricultural pesticides on the immune system of Xenopus laevis and Rana pipiens

International Nuclear Information System (INIS)

Christin, M.S.; Menard, L.; Gendron, A.D.; Ruby, S.; Cyr, D.; Marcogliese, D.J.; Rollins-Smith, L.; Fournier, M.

2004-01-01

Over the last 30 years, there have been mass declines in diverse geographic locations among amphibian populations. Multiple causes have been suggested to explain this decline. Among these, environmental pollution is gaining attention. Indeed, some chemicals of environmental concern are known to alter the immune system. Given that amphibians are frequently exposed to agricultural pesticides, it is possible that these pollutants alter their immune system and render them more susceptible to different pathogens. In this study, we exposed two frog species, Xenopus laevis and Rana pipiens, for a short period of time to a mixture of pesticides (atrazine, metribuzine, endosulfan, lindane, aldicarb and dieldrin) representative in terms of composition and concentrations to what it is found in the environment of the southwest region of the province of Quebec. The pesticides were known to be present in surface water of many tributaries of the St. Lawrence River (Quebec, Canada). Our results demonstrate that the mixture of pesticides could alter the cellularity and phagocytic activity of X. laevis and the lymphocyte proliferation of R. pipiens. Taken together, these results indicate that agricultural pesticides can alter some aspects of the immune response in frogs and could contribute to their global decline by rendering them more susceptible to certain infections

Effects of agricultural pesticides on the immune system of Xenopus laevis and Rana pipiens

Energy Technology Data Exchange (ETDEWEB)

Christin, M.S.; Menard, L.; Gendron, A.D.; Ruby, S.; Cyr, D.; Marcogliese, D.J.; Rollins-Smith, L.; Fournier, M

2004-03-30

Over the last 30 years, there have been mass declines in diverse geographic locations among amphibian populations. Multiple causes have been suggested to explain this decline. Among these, environmental pollution is gaining attention. Indeed, some chemicals of environmental concern are known to alter the immune system. Given that amphibians are frequently exposed to agricultural pesticides, it is possible that these pollutants alter their immune system and render them more susceptible to different pathogens. In this study, we exposed two frog species, Xenopus laevis and Rana pipiens, for a short period of time to a mixture of pesticides (atrazine, metribuzine, endosulfan, lindane, aldicarb and dieldrin) representative in terms of composition and concentrations to what it is found in the environment of the southwest region of the province of Quebec. The pesticides were known to be present in surface water of many tributaries of the St. Lawrence River (Quebec, Canada). Our results demonstrate that the mixture of pesticides could alter the cellularity and phagocytic activity of X. laevis and the lymphocyte proliferation of R. pipiens. Taken together, these results indicate that agricultural pesticides can alter some aspects of the immune response in frogs and could contribute to their global decline by rendering them more susceptible to certain infections.

Blood parasites of frogs from an equatorial African montane forest in western Uganda.

Science.gov (United States)

Readel, Anne M; Goldberg, Tony L

2010-04-01

In a survey of blood parasites in Ugandan frogs, 30 (17%) of 180 frogs were infected with at least 1 species of Hepatozoon or Trypanosoma, or with microfilariae. There were significant differences in the prevalence of parasitism among species, with parasitemia detected in only 3 of 9 species. The intensity of blood parasite infection ranged from 1 to 1,080 infected cells per 5,000 cells examined. Seasonal changes in the prevalence and intensity of parasitemia were not observed, nor was there any association between parasitemia and infection with the pandemic fungus Batrachochytrium dendrobatidis.

Gene expression and localization of two types of AQP5 in Xenopus tropicalis under hydration and dehydration.

Science.gov (United States)

Shibata, Yuki; Sano, Takahiro; Tsuchiya, Nobuhito; Okada, Reiko; Mochida, Hiroshi; Tanaka, Shigeyasu; Suzuki, Masakazu

2014-07-01

Two types of aquaporin 5 (AQP5) genes (aqp-xt5a and aqp-xt5b) were identified in the genome of Xenopus tropicalis by synteny comparison and molecular phylogenetic analysis. When the frogs were in water, AQP-xt5a mRNA was expressed in the skin and urinary bladder. The expression of AQP-xt5a mRNA was significantly increased in dehydrated frogs. AQP-xt5b mRNA was also detected in the skin and increased in response to dehydration. Additionally, AQP-xt5b mRNA began to be slightly expressed in the lung and stomach after dehydration. For the pelvic skin of hydrated frogs, immunofluorescence staining localized AQP-xt5a and AQP-xt5b to the cytoplasm of secretory cells of the granular glands and the apical plasma membrane of secretory cells of the small granular glands, respectively. After dehydration, the locations of both AQPs in their respective glands did not change, but AQP-xt5a was visualized in the cytoplasm of secretory cells of the small granular glands. For the urinary bladder, AQP-xt5a was observed in the apical plasma membrane and cytoplasm of a number of granular cells under normal hydration. After dehydration, AQP-xt5a was found in the apical membrane and cytoplasm of most granular cells. Injection of vasotocin into hydrated frogs did not induce these changes in the localization of AQP-xt5a in the small granular glands and urinary bladder, however. The results suggest that AQP-xt5a might be involved in water reabsorption from the urinary bladder during dehydration, whereas AQP-xt5b might play a role in water secretion from the small granular gland. Copyright © 2014 the American Physiological Society.

Unexpected metabolic disorders induced by endocrine disruptors in Xenopus tropicalis provide new lead for understanding amphibian decline.

Science.gov (United States)

Regnault, Christophe; Usal, Marie; Veyrenc, Sylvie; Couturier, Karine; Batandier, Cécile; Bulteau, Anne-Laure; Lejon, David; Sapin, Alexandre; Combourieu, Bruno; Chetiveaux, Maud; Le May, Cédric; Lafond, Thomas; Raveton, Muriel; Reynaud, Stéphane

2018-05-08

Despite numerous studies suggesting that amphibians are highly sensitive to endocrine disruptors (EDs), both their role in the decline of populations and the underlying mechanisms remain unclear. This study showed that frogs exposed throughout their life cycle to ED concentrations low enough to be considered safe for drinking water, developed a prediabetes phenotype and, more commonly, a metabolic syndrome. Female Xenopus tropicalis exposed from tadpole stage to benzo( a )pyrene or triclosan at concentrations of 50 ng⋅L -1 displayed glucose intolerance syndrome, liver steatosis, liver mitochondrial dysfunction, liver transcriptomic signature, and pancreatic insulin hypersecretion, all typical of a prediabetes state. This metabolic syndrome led to progeny whose metamorphosis was delayed and occurred while the individuals were both smaller and lighter, all factors that have been linked to reduced adult recruitment and likelihood of reproduction. We found that F 1 animals did indeed have reduced reproductive success, demonstrating a lower fitness in ED-exposed Xenopus Moreover, after 1 year of depuration, Xenopus that had been exposed to benzo( a )pyrene still displayed hepatic disorders and a marked insulin secretory defect resulting in glucose intolerance. Our results demonstrate that amphibians are highly sensitive to EDs at concentrations well below the thresholds reported to induce stress in other vertebrates. This study introduces EDs as a possible key contributing factor to amphibian population decline through metabolism disruption. Overall, our results show that EDs cause metabolic disorders, which is in agreement with epidemiological studies suggesting that environmental EDs might be one of the principal causes of metabolic disease in humans.

Diversification of African tree frogs (genus Leptopelis) in the highlands of Ethiopia.

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Reyes-Velasco, Jacobo; Manthey, Joseph D; Freilich, Xenia; Boissinot, Stéphane

2018-05-01

The frog genus Leptopelis is composed of ~50 species that occur across sub-Saharan Africa. The majority of these frogs are typically arboreal; however, a few species have evolved a fossorial lifestyle. Most species inhabit lowland forests, but a few species have adapted to high elevations. Five species of Leptopelis occupy the Ethiopian highlands and provide a good opportunity to study the evolutionary transition from an arboreal to a fossorial lifestyle, as well as the diversification in this biodiversity hot spot. We sequenced 14 nuclear and three mitochondrial genes, and generated thousands of SNPs from ddRAD sequencing to study the evolutionary relationships of Ethiopian Leptopelis. The five species of highland Leptopelis form a monophyletic group, which diversified during the late Miocene and Pliocene. We found strong population structure in the fossorial species L. gramineus, with levels of genetic differentiation between populations similar to those found between arboreal species. This could indicate that L. gramineus is a complex of cryptic species. We propose that after the original colonization of the Ethiopian highlands by the ancestor of the L. gramineus group, episodes of vicariance fragmented the ancestral populations of this group. We also report the re-evolution of arboreality in L. susanae, which evolved from a fossorial ancestor, a rare ecological switch in frogs that had previously been reported only once. © 2018 John Wiley & Sons Ltd.

Insertional Mutagenesis for Genes involved in Otic/Vestibular Development and Function in Xenopus Tropicalis

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Torrejon, Marcela; Li, Erica; Nguyen, Minh; Winfree, Seth; Wang, Esther; Reinsch, Sigrid; Dalton, Bonnie (Technical Monitor)

2002-01-01

Sensitivity to gravity is essential for spatial orientation. Consequently, the gravity receptor system is one of the phylogenetically oldest sensory systems, and the special adaptations that enhance sensitivity to gravity are highly conserved. The main goal of this project is to use Xenopus (frog) to identify genes expressed during vestibular and auditory development. These studies will lead a better understanding of the molecular mechanisms involved in vestibular and auditory development and function. We are using a gene-trap approach in Xenopus tropicalis with the green fluorescent protein (GFP) gene as the transgene reporter. GFP expression occurs only when the GFP gene is correctly integrated in actively transcribed genes. Using the GFP as a tag we can easily identify and clone the mutated gene. In addition, we can study the function of the mutated gene by analyzing the defects generated by insertion of the GFP transgene. To date we have tissue specific GFP expression in X. tropicalis including expression in ear, neural tube, kidney, muscle, eyes and nose. Our transgenic animals will soon reach maturity so that we can outcross them and analyze their progeny. Our next goal is to isolate RNA from our transgenics and clone the tagged genes using RACE-PCR. Currently we are optimizing the RACE-PCR method using transgenics with crystallin GFP expression.

Evolution of vertebrate transient receptor potential vanilloid 3 channels: opposite temperature sensitivity between mammals and western clawed frogs.

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Shigeru Saito

2011-04-01

Full Text Available Transient Receptor Potential (TRP channels serve as temperature receptors in a wide variety of animals and must have played crucial roles in thermal adaptation. The TRP vanilloid (TRPV subfamily contains several temperature receptors with different temperature sensitivities. The TRPV3 channel is known to be highly expressed in skin, where it is activated by warm temperatures and serves as a sensor to detect ambient temperatures near the body temperature of homeothermic animals such as mammals. Here we performed comprehensive comparative analyses of the TRPV subfamily in order to understand the evolutionary process; we identified novel TRPV genes and also characterized the evolutionary flexibility of TRPV3 during vertebrate evolution. We cloned the TRPV3 channel from the western clawed frog Xenopus tropicalis to understand the functional evolution of the TRPV3 channel. The amino acid sequences of the N- and C-terminal regions of the TRPV3 channel were highly diversified from those of other terrestrial vertebrate TRPV3 channels, although central portions were well conserved. In a heterologous expression system, several mammalian TRPV3 agonists did not activate the TRPV3 channel of the western clawed frog. Moreover, the frog TRPV3 channel did not respond to heat stimuli, instead it was activated by cold temperatures. Temperature thresholds for activation were about 16 °C, slightly below the lower temperature limit for the western clawed frog. Given that the TRPV3 channel is expressed in skin, its likely role is to detect noxious cold temperatures. Thus, the western clawed frog and mammals acquired opposite temperature sensitivity of the TRPV3 channel in order to detect environmental temperatures suitable for their respective species, indicating that temperature receptors can dynamically change properties to adapt to different thermal environments during evolution.

Tone and call responses of units in the auditory nerve and dorsal medullary nucleus of Xenopus laevis

DEFF Research Database (Denmark)

Elliott, Taffeta M.; Christensen-Dalsgaard, Jakob; Kelley, Darcy B.

2007-01-01

The clawed frog Xenopus laevis produces vocalizations consisting of distinct patterns of clicks. This study provides the first description of spontaneous, pure-tone and communication-signal evoked discharge properties of auditory nerve (n.VIII) fibers and dorsal medullary nucleus (DMN) cells...... in an obligatorily aquatic anuran. Responses of 297 n.VIII and 253 DMN units are analyzed for spontaneous rates (SR), frequency tuning, rate-intensity functions, and firing rate adaptation, with a view to how these basic characteristics shape responses to recorded call stimuli. Response properties generally resemble......Hz with approximately 500 Hz in 3 dB bandwidth. SRs range from 0 to 80 (n.VIII) and 0 to 73 spikes/s (DMN). Nerve and DMN units of all CFs follow click rates in natural calls,

Pan-African phylogeography of a model organism, the African clawed frog "Xenopus laevis"

Czech Academy of Sciences Publication Activity Database

Furman, B. L. S.; Bewick, A. J.; Harrison, T. L.; Greenbaum, E.; Gvoždík, Václav; Kusamba, C.; Evans, B. J.

2015-01-01

Roč. 24, č. 4 (2015), s. 909-925 ISSN 0962-1083 Institutional support: RVO:68081766 Keywords : gene flow * phylogeography * population genetics * species limits Subject RIV: EG - Zoology Impact factor: 5.947, year: 2015

Determining the influence of muscle operating length on muscle performance during frog swimming using a bio-robotic model

International Nuclear Information System (INIS)

Clemente, Christofer J; Richards, Christopher

2012-01-01

Frogs are capable of impressive feats of jumping and swimming. Recent work has shown that anuran hind limb muscles can operate at lengths longer than the ‘optimal length’. To address the implications of muscle operating length on muscle power output and swimming mechanics, we built a robotic frog hind limb model based upon Xenopus laevis. The model simulated the force–length and force–velocity properties of vertebrate muscle, within the skeletal environment. We tested three muscle starting lengths, representing long, optimal and short starting lengths. Increasing starting length increased maximum muscle power output by 27% from 98.1 W kg −1 when muscle begins shortening from the optimal length, to 125.1 W kg −1 when the muscle begins at longer initial lengths. Therefore, longer starting lengths generated greater hydrodynamic force for extended durations, enabling faster swimming speeds of the robotic frog. These swimming speeds increased from 0.15 m s −1 at short initial muscle lengths, to 0.39 m s −1 for the longest initial lengths. Longer starting lengths were able to increase power as the muscle's force–length curve was better synchronized with the muscle's activation profile. We further dissected the underlying components of muscle force, separating force–length versus force–velocity effects, showing a transition from force–length limitations to force–velocity limitations as starting length increased. (paper)

An environmentally relevant endocrine-disrupting antiandrogen, vinclozolin, affects calling behavior of male Xenopus laevis.

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Hoffmann, Frauke; Kloas, Werner

2010-09-01

Vinclozolin (VIN) is an antiandrogenic model substance as well as a common fungicide that can affect the endocrine system of vertebrates. The objective of this study was to investigate how VIN affects mate calling behavior of South African clawed frogs (Xenopus laevis) and whether it is effective at environmentally relevant concentrations. Male X. laevis were injected with human chorionic gonadotropin (hCG) to stimulate their androgen-controlled mate calling behavior and were treated with VIN at concentrations of 10(-6), 10(-8) and 10(-10)M. VIN at 10(-6)M reduced calling activity. Furthermore, the vocalization composition of VIN-treated X. laevis was altered. The call types advertisement calls and chirping are uttered by reproductively active males, whereas the call types growling, ticking, and rasping indicate a sexually unaroused state of a male. VIN at any of the tested concentrations led to a decrease in utterance of calls, which indicate a sexually aroused state of the males, and an increase in relative proportions of calls, indicating a sexually unaroused state of the males. Additionally, the mean duration of clicks and the number of accentuated clicks during the advertisement calls decreased at all concentrations of VIN. No significant differences were observed in any other temporal or spectral calling parameters between the treatments. This study illustrates that exposure to the antiandrogen VIN might result in a reduced reproductive success by altering mate calling behavior of X. laevis. Moreover, it suggests that the behavioral parameters examined in this study can be used as sensitive biomarkers for detecting antiandrogenic endocrine disrupting compounds in amphibians. Copyright (c) 2010 Elsevier Inc. All rights reserved.

Frog Statistics

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Whole Frog Project and Virtual Frog Dissection Statistics wwwstats output for January 1 through duplicate or extraneous accesses. For example, in these statistics, while a POST requesting an image is as well. Note that this under-represents the bytes requested. Starting date for following statistics

Pseudacris triseriata (western chorus frog) and Rana sylvatica (wood frog) chytridiomycosis

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Rittman, S.E.; Muths, E.; Green, D.E.

2003-01-01

The chytrid fungus Batrachochytrium dendrobatidis is a known pathogen of anuran amphibians, and has been correlated with amphibian die-offs worldwide (Daszak et. al. 1999. Emerging Infectious Diseases 5:735-748). In Colorado, B. dendrobatidis has infected Boreal toads (Bufo boreas) (Muths et. al., in review) and has been identified on museum specimens of northern leopard frogs (Rana pipiens) (Carey et. al. 1999. Develop. Comp. Immunol. 23:459-472). We report the first verified case of chytrid fungus in chorus frogs (Pseudacris triseriata) and wood frogs (Rana sylvatica) in the United States. We collected seven P. triseriata, and two adult and two juvenile R. sylvatica in the Kawuneeche Valley in Rocky Mountain National Park (RMNP) during June 2001. These animals were submitted to the National Wildlife Health Center (NWHC) as part of an amphibian health evaluation in RMNP. Chorus frogs were shipped in one container. Wood frog adults and juveniles were shipped in two separate containers. Histological examinations of all chorus frogs and 3 of 4 wood frogs were positive for chytrid fungus infection. The fourth (adult) wood frog was too decomposed for meaningful histology. Histological findings consisted of multifocally mild to diffusely severe infections of the epidermis of the ventrum and hindlimb digital skin. Chytrid thalli were confined to the thickened epidermis (hyperkeratosis), were spherical to oval, and occasional thalli contained characteristic discharge pores or zoospores (Green and Kagarise Sherman 1999. J. Herpetol 35:92-103; Fellers et al. 2001. Copeia 2001:945-953). We cannot confirm that all specimens carried the fungus at collection, because infection may have spread from one individual to all other individuals in each container during transport. Further sampling of amphibians in Kawuneeche Valley is warranted to determine the rate of infection and mortality in these populations.

Phylogenomics reveals rapid, simultaneous diversification of three major clades of Gondwanan frogs at the Cretaceous–Paleogene boundary

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Feng, Yan-Jie; Liang, Dan; Hillis, David M.; Cannatella, David C.; Zhang, Peng

2017-01-01

Frogs (Anura) are one of the most diverse groups of vertebrates and comprise nearly 90% of living amphibian species. Their worldwide distribution and diverse biology make them well-suited for assessing fundamental questions in evolution, ecology, and conservation. However, despite their scientific importance, the evolutionary history and tempo of frog diversification remain poorly understood. By using a molecular dataset of unprecedented size, including 88-kb characters from 95 nuclear genes of 156 frog species, in conjunction with 20 fossil-based calibrations, our analyses result in the most strongly supported phylogeny of all major frog lineages and provide a timescale of frog evolution that suggests much younger divergence times than suggested by earlier studies. Unexpectedly, our divergence-time analyses show that three species-rich clades (Hyloidea, Microhylidae, and Natatanura), which together comprise ∼88% of extant anuran species, simultaneously underwent rapid diversification at the Cretaceous–Paleogene (K–Pg) boundary (KPB). Moreover, anuran families and subfamilies containing arboreal species originated near or after the KPB. These results suggest that the K–Pg mass extinction may have triggered explosive radiations of frogs by creating new ecological opportunities. This phylogeny also reveals relationships such as Microhylidae being sister to all other ranoid frogs and African continental lineages of Natatanura forming a clade that is sister to a clade of Eurasian, Indian, Melanesian, and Malagasy lineages. Biogeographical analyses suggest that the ancestral area of modern frogs was Africa, and their current distribution is largely associated with the breakup of Pangaea and subsequent Gondwanan fragmentation. PMID:28673970

Phylogenomics reveals rapid, simultaneous diversification of three major clades of Gondwanan frogs at the Cretaceous-Paleogene boundary.

Science.gov (United States)

Feng, Yan-Jie; Blackburn, David C; Liang, Dan; Hillis, David M; Wake, David B; Cannatella, David C; Zhang, Peng

2017-07-18

Frogs (Anura) are one of the most diverse groups of vertebrates and comprise nearly 90% of living amphibian species. Their worldwide distribution and diverse biology make them well-suited for assessing fundamental questions in evolution, ecology, and conservation. However, despite their scientific importance, the evolutionary history and tempo of frog diversification remain poorly understood. By using a molecular dataset of unprecedented size, including 88-kb characters from 95 nuclear genes of 156 frog species, in conjunction with 20 fossil-based calibrations, our analyses result in the most strongly supported phylogeny of all major frog lineages and provide a timescale of frog evolution that suggests much younger divergence times than suggested by earlier studies. Unexpectedly, our divergence-time analyses show that three species-rich clades (Hyloidea, Microhylidae, and Natatanura), which together comprise ∼88% of extant anuran species, simultaneously underwent rapid diversification at the Cretaceous-Paleogene (K-Pg) boundary (KPB). Moreover, anuran families and subfamilies containing arboreal species originated near or after the KPB. These results suggest that the K-Pg mass extinction may have triggered explosive radiations of frogs by creating new ecological opportunities. This phylogeny also reveals relationships such as Microhylidae being sister to all other ranoid frogs and African continental lineages of Natatanura forming a clade that is sister to a clade of Eurasian, Indian, Melanesian, and Malagasy lineages. Biogeographical analyses suggest that the ancestral area of modern frogs was Africa, and their current distribution is largely associated with the breakup of Pangaea and subsequent Gondwanan fragmentation.

Identification of a Novel Vasodilatory Octapeptide from the Skin Secretion of the African Hyperoliid Frog, Kassina senegalensis.

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Du, Qiang; Wang, Hui; Ma, Chengbang; Wu, Yue; Xi, Xinping; Zhou, Mei; Chen, Tianbao; Shaw, Chris; Wang, Lei

2017-07-19

The defensive skin secretions of amphibians continue to be an excellent source of novel biologically-active peptides. Here we report the identification and pharmacological activity of a novel C-terminally amided myotropic octapeptide from the skin secretion of the African hyperoliid frog, Kassina senegalensis . The 8-amino acid peptide has the following primary structure: WMSLGWSL-amide and has a molecular mass of 978 Da. The primary structure and organisation of the biosynthetic precursor of WL-8 amide was successfully deduced from cloned skin secretion-derived cDNA. The open-reading frame encoded a single copy of WL-8, located at the C-terminus. Synthetic WL-8 amide was found to cause relaxation of rat tail artery smooth muscle with an EC 50 of 25.98 nM. This peptide is unique in terms of its primary structure and is unlike any other peptide previously isolated from an amphibian source which has been archived in the NCBI database. WL-8 amide thus represents the prototype of a novel family of myotropic peptide from amphibian defensive skin secretions.

Rhodopsin Forms Nanodomains in Rod Outer Segment Disc Membranes of the Cold-Blooded Xenopus laevis.

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Tatini Rakshit

Full Text Available Rhodopsin forms nanoscale domains (i.e., nanodomains in rod outer segment disc membranes from mammalian species. It is unclear whether rhodopsin arranges in a similar manner in amphibian species, which are often used as a model system to investigate the function of rhodopsin and the structure of photoreceptor cells. Moreover, since samples are routinely prepared at low temperatures, it is unclear whether lipid phase separation effects in the membrane promote the observed nanodomain organization of rhodopsin from mammalian species. Rod outer segment disc membranes prepared from the cold-blooded frog Xenopus laevis were investigated by atomic force microscopy to visualize the organization of rhodopsin in the absence of lipid phase separation effects. Atomic force microscopy revealed that rhodopsin nanodomains form similarly as that observed previously in mammalian membranes. Formation of nanodomains in ROS disc membranes is independent of lipid phase separation and conserved among vertebrates.

The neurogenic factor NeuroD1 is expressed in post-mitotic cells during juvenile and adult Xenopus neurogenesis and not in progenitor or radial glial cells.

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Laure Anne D'Amico

Full Text Available In contrast to mammals that have limited proliferation and neurogenesis capacities, the Xenopus frog exhibit a great potential regarding proliferation and production of new cells in the adult brain. This ability makes Xenopus a useful model for understanding the molecular programs required for adult neurogenesis. Transcriptional factors that control adult neurogenesis in vertebrate species undergoing widespread neurogenesis are unknown. NeuroD1 is a member of the family of proneural genes, which function during embryonic neurogenesis as a potent neuronal differentiation factor. Here, we study in detail the expression of NeuroD1 gene in the juvenile and adult Xenopus brains by in situ hybridization combined with immunodetections for proliferation markers (PCNA, BrdU or in situ hybridizations for cell type markers (Vimentin, Sox2. We found NeuroD1 gene activity in many brain regions, including olfactory bulbs, pallial regions of cerebral hemispheres, preoptic area, habenula, hypothalamus, cerebellum and medulla oblongata. We also demonstrated by double staining NeuroD1/BrdU experiments, after long post-BrdU administration survival times, that NeuroD1 gene activity was turned on in new born neurons during post-metamorphic neurogenesis. Importantly, we provided evidence that NeuroD1-expressing cells at this brain developmental stage were post-mitotic (PCNA- cells and not radial glial (Vimentin+ or progenitors (Sox2+ cells.

Effects of S-adenosylmethionine decarboxylase, polyamines, amino acids, and weak bases (amines and ammonia) on development and ribosomal RNA synthesis in Xenopus embryos.

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Shiokawa, Koichiro; Aso, Mai; Kondo, Takeshi; Takai, Jun-Ichi; Yoshida, Junki; Mishina, Takamichi; Fuchimukai, Kota; Ogasawara, Tsukasa; Kariya, Taro; Tashiro, Kosuke; Igarashi, Kazuei

2010-02-01

We have been studying control mechanisms of gene expression in early embryogenesis in a South African clawed toad Xenopus laevis, especially during the period of midblastula transition (MBT), or the transition from the phase of active cell division (cleavage stage) to the phase of extensive morphogenesis (post-blastular stages). We first found that ribosomal RNA synthesis is initiated shortly after MBT in Xenopus embryos and those weak bases, such as amines and ammonium ion, selectively inhibit the initiation and subsequent activation of rRNA synthesis. We then found that rapidly labeled heterogeneous mRNA-like RNA is synthesized in embryos at pre-MBT stage. We then performed cloning and expression studies of several genes, such as those for activin receptors, follistatin and aldolases, and then reached the studies of S-adenosylmethionine decarboxylase (SAMDC), a key enzyme in polyamine metabolism. Here, we cloned a Xenopus SAMDC cDNA and performed experiments to overexpress the in vitro-synthesized SAMDC mRNA in Xenopus early embryos, and found that the maternally preset program of apoptosis occurs in cleavage stage embryos, which is executed when embryos reach the stage of MBT. In the present article, we first summarize results on SAMDC and the maternal program of apoptosis, and then describe our studies on small-molecular-weight substances like polyamines, amino acids, and amines in Xenopus embryos. Finally, we summarize our studies on weak bases, especially on ammonium ion, as the specific inhibitor of ribosomal RNA synthesis in Xenopus embryonic cells.

The Expression of TALEN before Fertilization Provides a Rapid Knock-Out Phenotype in Xenopus laevis Founder Embryos.

Science.gov (United States)

Miyamoto, Kei; Suzuki, Ken-Ichi T; Suzuki, Miyuki; Sakane, Yuto; Sakuma, Tetsushi; Herberg, Sarah; Simeone, Angela; Simpson, David; Jullien, Jerome; Yamamoto, Takashi; Gurdon, J B

2015-01-01

Recent advances in genome editing using programmable nucleases have revolutionized gene targeting in various organisms. Successful gene knock-out has been shown in Xenopus, a widely used model organism, although a system enabling less mosaic knock-out in founder embryos (F0) needs to be explored in order to judge phenotypes in the F0 generation. Here, we injected modified highly active transcription activator-like effector nuclease (TALEN) mRNA to oocytes at the germinal vesicle (GV) stage, followed by in vitro maturation and intracytoplasmic sperm injection, to achieve a full knock-out in F0 embryos. Unlike conventional injection methods to fertilized embryos, the injection of TALEN mRNA into GV oocytes allows expression of nucleases before fertilization, enabling them to work from an earlier stage. Using this procedure, most of developed embryos showed full knock-out phenotypes of the pigmentation gene tyrosinase and/or embryonic lethal gene pax6 in the founder generation. In addition, our method permitted a large 1 kb deletion. Thus, we describe nearly complete gene knock-out phenotypes in Xenopus laevis F0 embryos. The presented method will help to accelerate the production of knock-out frogs since we can bypass an extra generation of about 1 year in Xenopus laevis. Meantime, our method provides a unique opportunity to rapidly test the developmental effects of disrupting those genes that do not permit growth to an adult able to reproduce. In addition, the protocol shown here is considerably less invasive than the previously used host transfer since our protocol does not require surgery. The experimental scheme presented is potentially applicable to other organisms such as mammals and fish to resolve common issues of mosaicism in founders.

Planar cell polarity enables posterior localization of nodal cilia and left-right axis determination during mouse and Xenopus embryogenesis.

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Dragana Antic

2010-02-01

Full Text Available Left-right asymmetry in vertebrates is initiated in an early embryonic structure called the ventral node in human and mouse, and the gastrocoel roof plate (GRP in the frog. Within these structures, each epithelial cell bears a single motile cilium, and the concerted beating of these cilia produces a leftward fluid flow that is required to initiate left-right asymmetric gene expression. The leftward fluid flow is thought to result from the posterior tilt of the cilia, which protrude from near the posterior portion of each cell's apical surface. The cells, therefore, display a morphological planar polarization. Planar cell polarity (PCP is manifested as the coordinated, polarized orientation of cells within epithelial sheets, or as directional cell migration and intercalation during convergent extension. A set of evolutionarily conserved proteins regulates PCP. Here, we provide evidence that vertebrate PCP proteins regulate planar polarity in the mouse ventral node and in the Xenopus gastrocoel roof plate. Asymmetric anterior localization of VANGL1 and PRICKLE2 (PK2 in mouse ventral node cells indicates that these cells are planar polarized by a conserved molecular mechanism. A weakly penetrant Vangl1 mutant phenotype suggests that compromised Vangl1 function may be associated with left-right laterality defects. Stronger functional evidence comes from the Xenopus GRP, where we show that perturbation of VANGL2 protein function disrupts the posterior localization of motile cilia that is required for leftward fluid flow, and causes aberrant expression of the left side-specific gene Nodal. The observation of anterior-posterior PCP in the mouse and in Xenopus embryonic organizers reflects a strong evolutionary conservation of this mechanism that is important for body plan determination.

Effects of forest fragmentation and habitat degradation on West African leaf-litter frogs

NARCIS (Netherlands)

Hillers, A.; Veith, M.; Rödel, M.-O.

2008-01-01

Habitat degradation alters the dynamics and composition of anuran assemblages in tropical forests. The effects of forest fragmentation on the composition of anuran assemblages are so far poorly known. We studied the joint influence of forest fragmentation and degradation on leaf-litter frogs. We

Development of the retinotectal system in the direct-developing frog Eleutherodactylus coqui in comparison with other anurans

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Schlosser Gerhard

2008-06-01

Full Text Available Abstract Background Frogs primitively have a biphasic life history with an aquatic larva (tadpole and a usually terrestrial adult. However, direct developing frogs of the genus Eleutherodactylus have lost a free living larval stage. Many larval structures never form during development of Eleutherodactylus, while limbs, spinal cord, and an adult-like cranial musculoskeletal system develop precociously. Results Here, I compare growth and differentiation of the retina and tectum and development of early axon tracts in the brain between Eleutherodactylus coqui and the biphasically developing frogs Discoglossus pictus, Physalaemus pustulosus, and Xenopus laevis using morphometry, immunohistochemical detection of proliferating cell nuclear antigen (PCNA and acetylated tubulin, biocytin tracing, and in situ hybridization for NeuroD. Findings of the present study indicate that retinotectal development was greatly altered during evolution of Eleutherodactlyus mostly due to acceleration of cell proliferation and growth in retina and tectum. However, differentiation of retina, tectum, and fiber tracts in the embryonic brain proceed along a conserved slower schedule and remain temporally coordinated with each other in E. coqui. Conclusion These findings reveal a mosaic pattern of changes in the development of the central nervous system (CNS during evolution of the direct developing genus Eleutherodactylus. Whereas differentiation events in directly interconnected parts of the CNS such as retina, tectum, and brain tracts remained coordinated presumably due to their interdependent development, they were dissociated from proliferation control and from differentiation events in other parts of the CNS such as the spinal cord. This suggests that mosaic evolutionary changes reflect the modular character of CNS development.

From frog integument to human skin: dermatological perspectives from frog skin biology

NARCIS (Netherlands)

Haslam, I.S.; Roubos, E.W.; Mangoni, M.L.; Yoshizato, K.; Vaudry, H.; Kloepper, J.E.; Pattwell, D.M.; Maderson, P.F.A.; Paus, R.

2014-01-01

For over a century, frogs have been studied across various scientific fields, including physiology, embryology, neuroscience, (neuro)endocrinology, ecology, genetics, behavioural science, evolution, drug development, and conservation biology. In some cases, frog skin has proven very successful as a

hmmr mediates anterior neural tube closure and morphogenesis in the frog Xenopus.

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Prager, Angela; Hagenlocher, Cathrin; Ott, Tim; Schambony, Alexandra; Feistel, Kerstin

2017-10-01

Development of the central nervous system requires orchestration of morphogenetic processes which drive elevation and apposition of the neural folds and their fusion into a neural tube. The newly formed tube gives rise to the brain in anterior regions and continues to develop into the spinal cord posteriorly. Conspicuous differences between the anterior and posterior neural tube become visible already during neural tube closure (NTC). Planar cell polarity (PCP)-mediated convergent extension (CE) movements are restricted to the posterior neural plate, i.e. hindbrain and spinal cord, where they propagate neural fold apposition. The lack of CE in the anterior neural plate correlates with a much slower mode of neural fold apposition anteriorly. The morphogenetic processes driving anterior NTC have not been addressed in detail. Here, we report a novel role for the breast cancer susceptibility gene and microtubule (MT) binding protein Hmmr (Hyaluronan-mediated motility receptor, RHAMM) in anterior neurulation and forebrain development in Xenopus laevis. Loss of hmmr function resulted in a lack of telencephalic hemisphere separation, arising from defective roof plate formation, which in turn was caused by impaired neural tissue narrowing. hmmr regulated polarization of neural cells, a function which was dependent on the MT binding domains. hmmr cooperated with the core PCP component vangl2 in regulating cell polarity and neural morphogenesis. Disrupted cell polarization and elongation in hmmr and vangl2 morphants prevented radial intercalation (RI), a cell behavior essential for neural morphogenesis. Our results pinpoint a novel role of hmmr in anterior neural development and support the notion that RI is a major driving force for anterior neurulation and forebrain morphogenesis. Copyright © 2017 Elsevier Inc. All rights reserved.

Deconstructing cartilage shape and size into contributions from embryogenesis, metamorphosis, and tadpole and frog growth.

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Rose, Christopher S; Murawinski, Danny; Horne, Virginia

2015-06-01

Understanding skeletal diversification involves knowing not only how skeletal rudiments are shaped embryonically, but also how skeletal shape changes throughout life. The pharyngeal arch (PA) skeleton of metamorphosing amphibians persists largely as cartilage and undergoes two phases of development (embryogenesis and metamorphosis) and two phases of growth (larval and post-metamorphic). Though embryogenesis and metamorphosis produce species-specific features of PA cartilage shape, the extents to which shape and size change during growth and metamorphosis remain unaddressed. This study uses allometric equations and thin-plate spline, relative warp and elliptic Fourier analyses to describe shape and size trajectories for the ventral PA cartilages of the frog Xenopus laevis in tadpole and frog growth and metamorphosis. Cartilage sizes scale negatively with body size in both growth phases and cartilage shapes scale isometrically or close to it. This implies that most species-specific aspects of cartilage shape arise in embryogenesis and metamorphosis. Contributions from growth are limited to minor changes in lower jaw (LJ) curvature that produce relative gape narrowing and widening in tadpoles and frogs, respectively, and most cartilages becoming relatively thinner. Metamorphosis involves previously unreported decreases in cartilage size as well as changes in cartilage shape. The LJ becomes slightly longer, narrower and more curved, and the adult ceratohyal emerges from deep within the resorbing tadpole ceratohyal. This contrast in shape and size changes suggests a fundamental difference in the underlying cellular pathways. The observation that variation in PA cartilage shape decreases with tadpole growth supports the hypothesis that isometric growth is required for the metamorphic remodeling of PA cartilages. It also supports the existence of shape-regulating mechanisms that are specific to PA cartilages and that resist local adaptation and phenotypic plasticity. �

The Observation of Frog Species at State University of Malang as a Preliminary Effort on Frog Conservation

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Dian Ratri Wulandari

2013-04-01

Full Text Available Frog is an amphibian which is widely spread around the world. Indonesia houses 450 species which represent 11% of frog species in the world. In Java Island alone, there live 42 species of frogs and toads. Frogs can be used as an environment indicator in that the presence of frog in a particular place indicates that the place stays natural and unpolluted. The 1st Campus of State University of Malang, which is located in the heart of Malang District, has been developing rapidly currently. Thus, it requires the construction of new various facilities to support its huge activities. Extensive construction can be destructive even damaging to the habitat of frog, which potentially threats the frog’s life, if it does not take the environmental impact into careful consideration. This study is aimed to identify the species of frog which survives at State University of Malang with, particularly the frog species found in 1995. Species identification was conducted by observing the morphological character. This study found that there were four species with three species remained survived in 1995; those were Duttaphrynus melanostictus, Polypedates leucomystax, and Kaloula baleta; and one new species called Rana chalconota. This study also revealed that there were four species which were extinct; those were Fejervarya cancrivora, Fejervarya limnocharis, Ingerophrynus biporcatus, and Occidoziga lima. This situation shows the decreasing amount of species from 7 to 4 within the last 17 years. This result indicates that there is a serious environmental degradation which causes the losing of frog habitats. Further research is needed to study the ecological condition changing in order to save the frog species.

Distinct neural and neuromuscular strategies underlie independent evolution of simplified advertisement calls.

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Leininger, Elizabeth C; Kelley, Darcy B

2013-04-07

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 divergent mechanisms, we examined activity from the calling brain and vocal organ (larynx) in two species that independently evolved simplified calls. We find that each species uses distinct neural and neuromuscular strategies to produce the simplified calls. Isolated Xenopus borealis brains produce fictive vocal patterns that match temporal patterns of actual male calls; the larynx converts nerve activity faithfully into muscle contractions and single clicks. In contrast, fictive patterns from isolated Xenopus boumbaensis brains are short bursts of nerve activity; the isolated larynx requires stimulus bursts to produce a single click of sound. Thus, unlike X. borealis, the output of the X. boumbaensis hindbrain vocal pattern generator is an ancestral burst-type pattern, transformed by the larynx into single clicks. Temporally simple advertisement calls in genetically distant species of Xenopus have thus arisen independently via reconfigurations of central and peripheral vocal neuroeffectors.

Histone titration against the genome sets the DNA-to-cytoplasm threshold for the Xenopus midblastula transition

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Amodeo, Amanda A.; Jukam, David; Straight, Aaron F.; Skotheim, Jan M.

2015-01-01

During early development, animal embryos depend on maternally deposited RNA until zygotic genes become transcriptionally active. Before this maternal-to-zygotic transition, many species execute rapid and synchronous cell divisions without growth phases or cell cycle checkpoints. The coordinated onset of transcription, cell cycle lengthening, and cell cycle checkpoints comprise the midblastula transition (MBT). A long-standing model in the frog, Xenopus laevis, posits that MBT timing is controlled by a maternally loaded inhibitory factor that is titrated against the exponentially increasing amount of DNA. To identify MBT regulators, we developed an assay using Xenopus egg extract that recapitulates the activation of transcription only above the DNA-to-cytoplasm ratio found in embryos at the MBT. We used this system to biochemically purify factors responsible for inhibiting transcription below the threshold DNA-to-cytoplasm ratio. This unbiased approach identified histones H3 and H4 as concentration-dependent inhibitory factors. Addition or depletion of H3/H4 from the extract quantitatively shifted the amount of DNA required for transcriptional activation in vitro. Moreover, reduction of H3 protein in embryos induced premature transcriptional activation and cell cycle lengthening, and the addition of H3/H4 shortened post-MBT cell cycles. Our observations support a model for MBT regulation by DNA-based titration and suggest that depletion of free histones regulates the MBT. More broadly, our work shows how a constant concentration DNA binding molecule can effectively measure the amount of cytoplasm per genome to coordinate division, growth, and development. PMID:25713373

Prey specialization and diet of frogs in Borneo

OpenAIRE

Ahlm, Kristoffer

2015-01-01

Earlier studies of the diet of frogs indicate that most adult frogs are mainly insectivorous. Overall, frogs are viewed more as generalists than specialists in terms of their diet. However, despite earlier studies, there are still gaps in our knowledge regarding what frogs tend to eat and the degree of specialization. The aim of this study was to investigate the diet choice of frogs in a tropical ecosystem. The present study was conducted in a well-known hotspot for frogs with 66 of the 156 k...

Genetic and genomic interactions of animals with different ploidy levels.

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Bogart, J P; Bi, K

2013-01-01

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 polyploid lizards in the genus Aspidoscelis) origins. Microsatellites are nuclear markers that can be used to analyze genetic recombinations, reproductive modes (e.g. Ambystoma) and recombination events (e.g. polyploid frogs such as Pelophylax esculentus). Hom(e)ologous chromosomes and rare intergenomic exchanges in allopolyploids have been distinguished by applying genome-specific fluorescent probes to chromosome spreads. Polyploids arise, and are maintained, through perturbations of the 'normal' meiotic program that would include pre-meiotic chromosome replication and genomic integrity of homologs. When possible, asexual, unisexual and bisexual polyploid species or biotypes interact with diploid relatives, and genes are passed from diploid to polyploid gene pools, which increase genetic diversity and ultimately evolutionary flexibility in the polyploid. When diploid relatives do not exist, polyploids can interact with another polyploid (e.g. species of African Clawed Frogs in the genus Xenopus). Some polyploid fish (e.g. salmonids) and frogs (Xenopus) represent independent lineages whose ancestors experienced whole genome duplication events. Some tetraploid frogs (P. esculentus) and fish (Squaliusalburnoides) may be in the process of becoming independent species, but diploid and triploid forms of these 'species' continue to genetically interact with the comparatively few tetraploid populations. Genetic and genomic interaction between polyploids and diploids is a complex

Identification of a candidate CD5 homologue in the amphibian Xenopus laevis.

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Jürgens, J B; Gartland, L A; Du Pasquier, L; Horton, J D; Göbel, T W; Cooper, M D

1995-11-01

We identified a novel T cell Ag in the South African clawed toad (Xenopus laevis) by a mAb designated 2B1. This Ag is present in relatively high levels on most thymocytes, approximately 65% of splenocytes, 55% of PBL, and 65% of intestinal lymphocytes, but is rarely seen on IgM+ B cells in any of these tissues. Lymphocytes bearing the 2B1 Ag proliferate in response to stimulation with Con A or PHA, whereas the 2B1- lymphocytes are reactive to LPS. Biochemical analysis indicates that this Ag is a differentially phosphorylated glycoprotein of 71 to 82 kDa. The protein core of 64 kDa bears both N- and O-linked carbohydrate side chains. The amino-terminal protein sequence of the 2B1 Ag shares significant homology with both the macrophage scavenger receptor type 1 motif and the mammalian CD5/CD6 family. The biochemical characteristics and cellular distribution of the 2B1 Ag suggest that it represents the CD5 homologue in X. laevis. While T cells constitutively express this highly conserved molecule, Xenopus B cells acquire the CD5 homologue only when they are stimulated in the presence of T cells.

Xenopus egg cytoplasm with intact actin.

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Field, Christine M; Nguyen, Phuong A; Ishihara, Keisuke; Groen, Aaron C; Mitchison, Timothy J

2014-01-01

We report optimized methods for preparing Xenopus egg extracts without cytochalasin D, that we term "actin-intact egg extract." These are undiluted egg cytoplasm that contains abundant organelles, and glycogen which supplies energy, and represents the least perturbed cell-free cytoplasm preparation we know of. We used this system to probe cell cycle regulation of actin and myosin-II dynamics (Field et al., 2011), and to reconstitute the large, interphase asters that organize early Xenopus embryos (Mitchison et al., 2012; Wühr, Tan, Parker, Detrich, & Mitchison, 2010). Actin-intact Xenopus egg extracts are useful for analysis of actin dynamics, and interaction of actin with other cytoplasmic systems, in a cell-free system that closely mimics egg physiology, and more generally for probing the biochemistry and biophysics of the egg, zygote, and early embryo. Detailed protocols are provided along with assays used to check cell cycle state and tips for handling and storing undiluted egg extracts. © 2014 Elsevier Inc. All rights reserved.

The histone H5 variant in Xenopus laevis

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Moorman, A. F.; de Boer, P. A.; Linders, M. T.; Charles, R.

1984-01-01

The presumptive histone H5 of Xenopus laevis has been characterized by SDS and acid-urea-Triton polyacrylamide gel electrophoresis and compared with chicken histone H5. Chicken H5 has a lower electrophoretic mobility compared to that of Xenopus H5 in both gel systems. It is shown, using a polyclonal

Monophyly of the species of Hepatozoon (Adeleorina: Hepatozoidae) parasitizing (African) anurans, with the description of three new species from hyperoliid frogs in South Africa.

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Netherlands, Edward C; Cook, Courtney A; Du Preez, Louis H; Vanhove, Maarten P M; Brendonck, Luc; Smit, Nico J

2017-12-04

Haemogregarines (Apicomplexa: Adeleiorina) are a diverse group of haemoparasites reported from almost all vertebrate classes. The most commonly recorded haemogregarines to parasitize anurans are species of Hepatozoon Miller, 1908. To date 16 Hepatozoon species have been described from anurans in Africa, with only a single species, Hepatozoon hyperolli (Hoare, 1932), infecting a member of the Hyperoliidae. Furthermore, only two Hepatozoon species are known from South African anurans, namely Hepatozoon theileri (Laveran, 1905) and Hepatozoon ixoxo Netherlands, Cook and Smit, 2014, from Amietia delalandii (syn. Amietia quecketti) and three Sclerophrys species, respectively. Blood samples were collected from a total of 225 individuals representing nine hyperoliid species from several localities throughout northern KwaZulu-Natal, South Africa. Twenty frogs from three species were found positive for haemogregarines, namely Afrixalus fornasinii (6/14), Hyperolius argus (2/39), and Hyperolius marmoratus (12/74). Based on morphological characteristics, morphometrics and molecular findings three new haemogregarine species, Hepatozoon involucrum Netherlands, Cook and Smit n. sp., Hepatozoon tenuis Netherlands, Cook and Smit n. sp. and Hepatozoon thori Netherlands, Cook and Smit n. sp., are described from hyperoliid hosts. Furthermore, molecular analyses show anuran Hepatozoon species to be a separate monophyletic group, with species isolated from African hosts forming a monophyletic clade within this cluster.

The RNA-binding protein xCIRP2 is involved in apoptotic tail regression during metamorphosis in Xenopus laevis tadpoles.

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Eto, Ko; Iwama, Tomoyuki; Tajima, Tatsuya; Abe, Shin-ichi

2012-10-01

Frog metamorphosis induced by thyroid hormone (TH) involves not only cell proliferation and differentiation in reconstituted organs such as limbs, but also apoptotic cell death in degenerated organs such as tails. However, the molecular mechanisms directing the TH-dependent cell fate determination remain unclear. We have previously identified from newts an RNA-binding protein (nRBP) acting as the regulator governing survival and death in germ cells during spermatogenesis. To investigate the molecular events leading the tail resorption during metamorphosis, we analyzed the expression, the functional role in apoptosis, and the regulation of xCIRP2, a frog homolog of nRBP, in tails of Xenopus laevis tadpoles. At the prometamorphic stage, xCIRP2 protein is expressed in fibroblast, epidermal, nerve, and muscular cells and localized in their cytoplasm. When spontaneous metamorphosis progressed, the level of xCIRP2 mRNA remained unchanged but the amount of the protein decreased. In organ cultures of tails at the prometamorphic stage, xCIRP2 protein decreased before their lengths shortened during TH-dependent metamorphosis. The inhibition of calpain or proteasome attenuated the TH-induced decrease of xCIRP2 protein in tails, impairing their regression. These results suggest that xCIRP2 protein is downregulated through calpain- and proteasome-mediated proteolysis in response to TH at the onset of metamorphosis, inducing apoptosis in tails and thereby degenerating them. Copyright © 2012 Elsevier Inc. All rights reserved.

Ecotoxicological Assessment of Sediment Leachates of Small Watercourses in the Brno City Suburban Area (South Moravia, Czech Republic

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Miroslava Beklová

2010-01-01

Full Text Available Sediments of two small watercourses Leskava and Troubsky Brook in the Brno city suburban area were examined for their ecotoxicity. Using a standard procedure, extracts of the sediments were prepared for diagnostic tests. These extracts were tested for acute toxicity to fresh-water organisms. The ecotoxicological tests were performed on the fresh-water alga Pseudokirchneriella subcapitata, the vascular water plant Lemna minor, on a representative of invertebrates – the water flea Daphnia magna and on the Xenopus laevis frog embryo and luminiscent Vibrio fischeri bacteria. Possible toxic effects were evaluated using the test determining the inhibition of the growth of white mustard root Sinapis alba. Results of ecotoxicological assessment of sediment leachates showed that their quality varied significantly during the year. Differences were found between results of sediment evaluations from different collection profiles, which may indicate effects of point source pollution. Of the ecotoxicological tests used, the most sensitive organisms included the green algae Pseudokirchneriella subcapitata, bioluminiscent bacteria Vibrio fischeri and the African clawed frog Xenopus laevis. The highest concentrations of arsenic were found by chemical analysis in both spring and autumn sediment leachate samples collected at Site L1 (Leskava. The highest organic pollutant concentrations were found in autumn sediment leachate samples from Site L1. In total PAH sums, phenanthrene was the dominant pollutant at all the sites investigated.

Reactivation of larval keratin gene (krt62.L) in blastema epithelium during Xenopus froglet limb regeneration.

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Satoh, Akira; Mitogawa, Kazumasa; Saito, Nanami; Suzuki, Miyuki; Suzuki, Ken-Ichi T; Ochi, Haruki; Makanae, Aki

2017-12-15

Limb regeneration is considered a form of limb redevelopment because of the molecular and morphological similarities. Forming a regeneration blastema is, in essence, creating a developing limb bud in an adult body. This reactivation of a developmental process in a mature body is worth studying. Xenopus laevis has a biphasic life cycle that involves distinct larval and adult stages. These distinct developmental stages are useful for investigating the reactivation of developmental processes in post-metamorphic frogs (froglets). In this study, we focused on the re-expression of a larval gene (krt62.L) during Xenopus froglet limb regeneration. Recently renamed krt62.L, this gene was known as the larval keratin (xlk) gene, which is specific to larval-tadpole stages. During limb regeneration in a froglet, krt62.L was re-expressed in a basal layer of blastema epithelium, where adult-specific keratin (Krt12.6.S) expression was also observable. Nerves produce important regulatory factors for amphibian limb regeneration, and also play a role in blastema formation and maintenance. The effect of nerve function on krt62.L expression could be seen in the maintenance of krt62.L expression, but not in its induction. When an epidermis-stripped limb bud was grafted in a froglet blastema, the grafted limb bud could reach the digit-forming stage. This suggests that krt62.L-positive froglet blastema epithelium is able to support the limb development process. These findings imply that the developmental process is locally reactivated in an postmetamorphic body during limb regeneration. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Complete Genome Sequence of Frog virus 3, Isolated from a Strawberry Poison Frog (Oophaga pumilio) Imported from Nicaragua into the Netherlands.

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Saucedo, Bernardo; Hughes, Joseph; van Beurden, Steven J; Suárez, Nicolás M; Haenen, Olga L M; Voorbergen-Laarman, Michal; Gröne, Andrea; Kik, Marja J L

2017-08-31

Frog virus 3 was isolated from a strawberry poison frog ( Oophaga pumilio ) imported from Nicaragua via Germany to the Netherlands, and its complete genome sequence was determined. Frog virus 3 isolate Op /2015/Netherlands/UU3150324001 is 107,183 bp long and has a nucleotide similarity of 98.26% to the reference Frog virus 3 isolate. Copyright © 2017 Saucedo et al.

The evolution of reproductive diversity in Afrobatrachia: A phylogenetic comparative analysis of an extensive radiation of African frogs

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Portik, Daniel M.; Blackburn, David C.

2016-01-01

The reproductive modes of anurans (frogs and toads) are the most diverse of terrestrial vertebrates, and a major challenge is identifying selective factors that promote the evolution or retention of reproductive modes across clades. Terrestrialized anuran breeding strategies have evolved repeatedly from the plesiomorphic fully aquatic reproductive mode, a process thought to occur through intermediate reproductive stages. Several selective forces have been proposed for the evolution of terrestrialized reproductive traits, but factors such as water systems and co‐evolution with ecomorphologies have not been investigated. We examined these topics in a comparative phylogenetic framework using Afrobatrachian frogs, an ecologically and reproductively diverse clade representing more than half of the total frog diversity found in Africa (∼400 species). We infer direct development has evolved twice independently from terrestrialized reproductive modes involving subterranean or terrestrial oviposition, supporting evolution through intermediate stages. We also detect associations between specific ecomorphologies and oviposition sites, and demonstrate arboreal species exhibit an overall shift toward using lentic water systems for breeding. These results indicate that changes in microhabitat use associated with ecomorphology, which allow access to novel sites for reproductive behavior, oviposition, or larval development, may also promote reproductive mode diversity in anurans. PMID:27402182

Innate Immune Response and Off-Target Mis-splicing Are Common Morpholino-Induced Side Effects in Xenopus.

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Gentsch, George E; Spruce, Thomas; Monteiro, Rita S; Owens, Nick D L; Martin, Stephen R; Smith, James C

2018-03-12

Antisense morpholino oligomers (MOs) have been indispensable tools for developmental biologists to transiently knock down (KD) genes rather than to knock them out (KO). Here we report on the implications of genetic KO versus MO-mediated KD of the mesoderm-specifying Brachyury paralogs in the frog Xenopus tropicalis. While both KO and KD embryos fail to activate the same core gene regulatory network, resulting in virtually identical morphological defects, embryos injected with control or target MOs also show a systemic GC content-dependent immune response and many off-target splicing defects. Optimization of MO dosage and increasing incubation temperatures can mitigate, but not eliminate, these MO side effects, which are consistent with the high affinity measured between MO and off-target sequence in vitro. We conclude that while MOs can be useful to profile loss-of-function phenotypes at a molecular level, careful attention must be paid to their immunogenic and off-target side effects. Copyright © 2018 The Francis Crick Institute. Published by Elsevier Inc. All rights reserved.

A glyphosate micro-emulsion formulation displays teratogenicity in Xenopus laevis.

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Bonfanti, Patrizia; Saibene, M; Bacchetta, R; Mantecca, P; Colombo, A

2018-02-01

Glyphosate is the active ingredient in broad-spectrum herbicide formulations used in agriculture, domestic area and aquatic weed control worldwide. Its market is growing steadily concurrently with the cultivation of glyphosate-tolerant transgenic crops and emergence of weeds less sensitive to glyphosate. Ephemeral and lentic waters near to agricultural lands, representing favorite habitats for amphibian reproduction and early life-stage development, may thus be contaminated by glyphosate based herbicides (GBHs) residues. Previous studies on larval anuran species highlighted increased mortality and growth effects after exposure to different GBHs in comparison to glyphosate itself, mainly because of the surfactants such as polyethoxylated tallow amine present in the formulations. Nevertheless, these conclusions are not completely fulfilled when the early development, characterized by primary organogenesis events, is considered. In this study, we compare the embryotoxicity of Roundup ® Power 2.0, a new GBH formulation currently authorized in Italy, with that of technical grade glyphosate using the Frog Embryo Teratogenesis Assay-Xenopus (FETAX). Our results evidenced that glyphosate was not embryolethal and only at the highest concentration (50 mg a.e./L) caused edemas. Conversely, Roundup ® Power 2.0 exhibited a 96 h LC50 of 24.78 mg a.e./L and a 96 h EC50 of 7.8 mg a.e./L. A Teratogenic Index of 3.4 was derived, pointing out the high teratogenic potential of the Roundup ® Power 2.0. Specific concentration-dependent abnormal phenotypes, such as craniofacial alterations, microphthalmia, narrow eyes and forebrain regionalization defects were evidenced by gross malformation screening and histopathological analysis. These phenotypes are coherent with those evidenced in Xenopus laevis embryos injected with glyphosate, allowing us to hypothesize that the teratogenicity observed for Roundup ® Power 2.0 may be related to the improved efficacy in delivering

Effect of allyl isothiocyanate on developmental toxicity in exposed Xenopus laevis embryos

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John Russell Williams

2015-01-01

Full Text Available The pungent natural compound allyl isothiocyanate isolated from the seeds of Cruciferous (Brassica plants such as mustard is reported to exhibit numerous beneficial health-promoting antimicrobial, antifungal, anticarcinogenic, cardioprotective, and neuroprotective properties. Because it is also reported to damage DNA and is toxic to aquatic organisms, the objective of the present study was to determine whether it possesses teratogenic properties. The frog embryo teratogenesis assay-Xenopus (FETAX was used to determine the following measures of developmental toxicity of the allyl isothiocyanate: (a 96-h LC50, defined as the median concentration causing 50% embryo lethality; (b 96-h EC50, defined as the median concentration causing 50% malformations of the surviving embryos; and (c teratogenic malformation index (TI, equal to 96-h LC50/96-h EC50. The quantitative results and the photographs of embryos before and after exposure suggest that allyl isothiocyanate seems to exhibit moderate teratogenic properties. The results also indicate differences in the toxicity of allyl isothiocyanate toward exposed embryos observed in the present study compared to reported adverse effects of allyl isothiocyanate in fish, rodents, and humans. The significance of the results for food safety and possible approaches to protect against adverse effects of allyl isothiocyanate are discussed.

Peptide secretion in the cutaneous glands of South American tree frog Phyllomedusa bicolor: an ultrastructural study.

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Lacombe, C; Cifuentes-Diaz, C; Dunia, I; Auber-Thomay, M; Nicolas, P; Amiche, M

2000-09-01

The development of the dermal glands of the arboreal frog Phyllomedusa bicolor was investigated by immunocytochemistry and electron microscopy. The 3 types of glands (mucous, lipid and serous) differed in size and secretory activity. The mucous and serous glands were apparent in the tadpole skin, whereas the lipid glands developed later in ontogenesis. The peptide antibiotics dermaseptins and the D-amino acid-containing peptide opioids dermorphins and deltorphins are abundant in the skin secretions of P. bicolor. Although these peptides differ in their structure and activity they are derived from precursors that have very similar preproregions. We used an antibody to the common preproregion of preprodermaseptins and preprodeltorphins and immunofluorescence analysis to show that only the serous glands are specifically involved in the biosynthesis and secretion of dermaseptins and deltorphins. Scanning and transmission electron microscopy revealed that the serous glands of P bicolor have morphological features, especially the secretory granules, which differ from those of the glands in Xenopus laevis skin.

The polymorphic integumentary mucin B.1 from Xenopus laevis contains the short consensus repeat.

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Probst, J C; Hauser, F; Joba, W; Hoffmann, W

1992-03-25

The frog integumentary mucin B.1 (FIM-B.1), discovered by molecular cloning, contains a cysteine-rich C-terminal domain which is homologous with von Willebrand factor. With the help of the polymerase chain reaction, we now characterize a contiguous region 5' to the von Willebrand factor domain containing the short consensus repeat typical of many proteins from the complement system. Multiple transcripts have been cloned, which originate from a single animal and differ by a variable number of tandem repeats (rep-33 sequences). These different transcripts probably originate solely from two genes and are generated presumably by alternative splicing of an huge array of functional cassettes. This model is supported by analysis of genomic FIM-B.1 sequences from Xenopus laevis. Here, rep-33 sequences are arranged in an interrupted array of individual units. Additionally, results of Southern analysis revealed genetic polymorphism between different animals which is predicted to be within the tandem repeats. A first investigation of the predicted mucins with the help of a specific antibody against a synthetic peptide determined the molecular mass of FIM-B.1 to greater than 200 kDa. Here again, genetic polymorphism between different animals is detected.

Parental care in Hemisus (Anura: Hemisotidae) | van Dijk | African ...

African Journals Online (AJOL)

Accounts of parental care in Anura frequently include mention of the South African frog genus Hemisus and derive their infonnation from what was written by the late Vincent Wager, An analysis is given of what exactly is known and what has been written, either from original observations or derived from other publications.

A Tunable Silk Hydrogel Device for Studying Limb Regeneration in Adult Xenopus Laevis.

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Anne Golding

Full Text Available In certain amphibian models limb regeneration can be promoted or inhibited by the local wound bed environment. This research introduces a device that can be utilized as an experimental tool to characterize the conditions that promotes limb regeneration in the adult frog (Xenopus laevis model. In particular, this device was designed to manipulate the local wound environment via a hydrogel insert. Initial characterization of the hydrogel insert revealed that this interaction had a significant influence on mechanical forces to the animal, due to the contraction of the hydrogel. The material and mechanical properties of the hydrogel insert were a factor in the device design in relation to the comfort of the animal and the ability to effectively manipulate the amputation site. The tunable features of the hydrogel were important in determining the pro-regenerative effects in limb regeneration, which was measured by cartilage spike formation and quantified by micro-computed tomography. The hydrogel insert was a factor in the observed morphological outcomes following amputation. Future work will focus on characterizing and optimizing the device's observed capability to manipulate biological pathways that are essential for limb regeneration. However, the present work provides a framework for the role of a hydrogel in the device and a path forward for more systematic studies.

Complete Genome Sequence of Frog virus 3, Isolated from a Strawberry Poison Frog (Oophaga pumilio) Imported from Nicaragua into the Netherlands

NARCIS (Netherlands)

Saucedo, Bernardo; Hughes, Joseph; van Beurden, Steven J; Suárez, Nicolás M; Haenen, Olga L M; Voorbergen-Laarman, Michal A; Gröne, Andrea; Kik, Marja J L

2017-01-01

Frog virus 3 was isolated from a strawberry poison frog (Oophaga pumilio) imported from Nicaragua via Germany to the Netherlands, and its complete genome sequence was determined. Frog virus 3 isolate Op/2015/Netherlands/UU3150324001 is 107,183 bp long and has a nucleotide similarity of 98.26% to the

Complete genome sequence of frog virus 3, isolated from a strawberry poison frog (Oophaga pumilio) imported from nicaragua into the Netherlands

NARCIS (Netherlands)

Saucedo, Bernardo; Hughes, Joseph; Beurden, van Steven J.; Suárez, Nicolás M.; Haenen, Olga L.M.; Voorbergen-Laarman, Michal; Gröne, Andrea; Kika, Marja J.L.

2017-01-01

Frog virus 3 was isolated from a strawberry poison frog (Oophaga pumilio) imported from Nicaragua via Germany to the Netherlands, and its complete genome sequence was determined. Frog virus 3 isolate Op/2015/Netherlands/UU3150324001 is 107,183 bp long and has a nucleotide similarity of 98.26% to the

Triclosan exposure alters postembryonic development in a Pacific tree frog (Pseudacris regilla) Amphibian Metamorphosis Assay (TREEMA)

International Nuclear Information System (INIS)

Marlatt, Vicki L.; Veldhoen, Nik; Lo, Bonnie P.; Bakker, Dannika; Rehaume, Vicki; Vallée, Kurtis; Haberl, Maxine; Shang, Dayue; Aggelen, Graham C. van; Skirrow, Rachel C.; Elphick, James R.; Helbing, Caren C.

2013-01-01

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 thyroxine (T 4 ), 0.3, 3 and 30 μg/L (nominal) TCS, or combined T 4 /TCS treatments. Exposure effects were scored by morphometric (developmental stage, wet weight, and body, snout-vent and hindlimb lengths) and molecular (mRNA abundance using quantitative real time polymerase chain reaction) criteria. T 4 treatment alone accelerated development concomitant with altered levels of TH receptors α and β, proliferating cell nuclear antigen, and gelatinase B mRNAs in the brain and tail. We observed TCS-induced perturbations in all of the molecular and morphological endpoints indicating that TCS exposure disrupts coordination of postembryonic tadpole development. Clear alterations in molecular endpoints were evident at day 2 whereas the earliest morphological effects appeared at day 4 and were most evident at day 21. Although TCS alone (3 and 30 μg/L) was protective against tadpole mortality, this protection was lost in the presence of T 4 . The Pacific tree frog is the most sensitive species examined to date displaying disruption of TH-mediated development by a common antimicrobial agent.

Triclosan exposure alters postembryonic development in a Pacific tree frog (Pseudacris regilla) Amphibian Metamorphosis Assay (TREEMA)

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Marlatt, Vicki L. [Nautilus Environmental, 8864 Commerce Court, Burnaby, B.C. V5A 4N7 (Canada); Veldhoen, Nik [Department of Biochemistry and Microbiology, University of Victoria, P.O. Box 3055 Stn CSC, Victoria, B.C. V8W 3P6 (Canada); Lo, Bonnie P. [Nautilus Environmental, 8864 Commerce Court, Burnaby, B.C. V5A 4N7 (Canada); Bakker, Dannika; Rehaume, Vicki; Vallee, Kurtis [Department of Biochemistry and Microbiology, University of Victoria, P.O. Box 3055 Stn CSC, Victoria, B.C. V8W 3P6 (Canada); Haberl, Maxine; Shang, Dayue; Aggelen, Graham C. van; Skirrow, Rachel C. [Pacific and Yukon Laboratory for Environmental Testing, Emergencies Operational Analytical Laboratories and Research Support Division, Environment Canada, 2645 Dollarton Highway, North Vancouver, B.C. V7H 1B1 (Canada); Elphick, James R. [Nautilus Environmental, 8864 Commerce Court, Burnaby, B.C. V5A 4N7 (Canada); Helbing, Caren C., E-mail: chelbing@uvic.ca [Department of Biochemistry and Microbiology, University of Victoria, P.O. Box 3055 Stn CSC, Victoria, B.C. V8W 3P6 (Canada)

2013-01-15

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 {mu}g/L thyroxine (T{sub 4}), 0.3, 3 and 30 {mu}g/L (nominal) TCS, or combined T{sub 4}/TCS treatments. Exposure effects were scored by morphometric (developmental stage, wet weight, and body, snout-vent and hindlimb lengths) and molecular (mRNA abundance using quantitative real time polymerase chain reaction) criteria. T{sub 4} treatment alone accelerated development concomitant with altered levels of TH receptors {alpha} and {beta}, proliferating cell nuclear antigen, and gelatinase B mRNAs in the brain and tail. We observed TCS-induced perturbations in all of the molecular and morphological endpoints indicating that TCS exposure disrupts coordination of postembryonic tadpole development. Clear alterations in molecular endpoints were evident at day 2 whereas the earliest morphological effects appeared at day 4 and were most evident at day 21. Although TCS alone (3 and 30 {mu}g/L) was protective against tadpole mortality, this protection was lost in the presence of T{sub 4}. The Pacific tree frog is the most sensitive species examined to date displaying disruption of TH-mediated development by a common antimicrobial agent.

Pemanfaatan kulit kodok (bull frog

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Muchtar Lutfie

1995-06-01

Full Text Available The objective of this study was to measure the tensile strength and the elongation of finished leather made from Bull Frog skin, so that the utilization of that leather can be specified. The samples used were twenty pieces of wet salted Bull Frog skin from East Java which have been processed to finished leather using chromosal B. and Irgatan LV as the tanning agents. Laboratory tests shawed that the average tensile strength was 177,675 Kg/Cm2 and the average elongation was 89,9%. Based on those results, it can be concluded that Bull Frog leather was suitable for leather goods such as bag, wallet, etc. so it can be used as substitute for Glace leather.

Reversal to air-driven sound production revealed by a molecular phylogeny of tongueless frogs, family Pipidae

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Glaw Frank

2011-04-01

Full Text Available Abstract Background Evolutionary novelties often appear by conferring completely new functions to pre-existing structures or by innovating the mechanism through which a particular function is performed. Sound production plays a central role in the behavior of frogs, which use their calls to delimit territories and attract mates. Therefore, frogs have evolved complex vocal structures capable of producing a wide variety of advertising sounds. It is generally acknowledged that most frogs call by moving an air column from the lungs through the glottis with the remarkable exception of the family Pipidae, whose members share a highly specialized sound production mechanism independent of air movement. Results Here, we performed behavioral observations in the poorly known African pipid genus Pseudhymenochirus and document that the sound production in this aquatic frog is almost certainly air-driven. However, morphological comparisons revealed an indisputable pipid nature of Pseudhymenochirus larynx. To place this paradoxical pattern into an evolutionary framework, we reconstructed robust molecular phylogenies of pipids based on complete mitochondrial genomes and nine nuclear protein-coding genes that coincided in placing Pseudhymenochirus nested among other pipids. Conclusions We conclude that although Pseudhymenochirus probably has evolved a reversal to the ancestral non-pipid condition of air-driven sound production, the mechanism through which it occurs is an evolutionary innovation based on the derived larynx of pipids. This strengthens the idea that evolutionary solutions to functional problems often emerge based on previous structures, and for this reason, innovations largely depend on possibilities and constraints predefined by the particular history of each lineage.

The unexpected teratogenicity of RXR antagonist UVI3003 via activation of PPARγ in Xenopus tropicalis

International Nuclear Information System (INIS)

Zhu, Jingmin; Janesick, Amanda; Wu, Lijiao; Hu, Lingling; Tang, Weiyi; Blumberg, Bruce; Shi, Huahong

2017-01-01

The RXR agonist (triphenyltin, TPT) and the RXR antagonist (UVI3003) both show teratogenicity and, unexpectedly, induce similar malformations in Xenopus tropicalis embryos. In the present study, we exposed X. tropicalis embryos to UVI3003 in seven specific developmental windows and identified changes in gene expression. We further measured the ability of UVI3003 to activate Xenopus RXRα (xRXRα) and PPARγ (xPPARγ) in vitro and in vivo. We found that UVI3003 activated xPPARγ either in Cos7 cells (in vitro) or Xenopus embryos (in vivo). UVI3003 did not significantly activate human or mouse PPARγ in vitro; therefore, the activation of Xenopus PPARγ by UVI3003 is novel. The ability of UVI3003 to activate xPPARγ explains why UVI3003 and TPT yield similar phenotypes in Xenopus embryos. Our results indicate that activating PPARγ leads to teratogenic effects in Xenopus embryos. More generally, we infer that chemicals known to specifically modulate mammalian nuclear hormone receptors cannot be assumed to have the same activity in non-mammalian species, such as Xenopus. Rather they must be tested for activity and specificity on receptors of the species in question to avoid making inappropriate conclusions. - Highlights: • UVI3003 is a RXRs antagonist and shows teratogenicity to Xenopus embryos. • UVI3003 activated xPPARγ either in Cos7 cells or Xenopus embryos. • UVI3003 did not activate human or mouse PPARγ in Cos7 cells. • Activating PPARγ leads to teratogenic effects in Xenopus embryos.

Vectorcardiogram of the 'Man-Frog' | Skowron | South African ...

African Journals Online (AJOL)

South African Medical Journal. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 47, No 6 (1973) >. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Download this PDF file. The PDF file you selected should ...

Adult-type myogenesis of the frog Xenopus laevis specifically suppressed by notochord cells but promoted by spinal cord cells in vitro.

Science.gov (United States)

Yamane, Hitomi; Ihara, Setsunosuke; Kuroda, Masaaki; Nishikawa, Akio

2011-08-01

Larval-to-adult myogenic conversion occurs in the dorsal muscle but not in the tail muscle during Xenopus laevis metamorphosis. To know the mechanism for tail-specific suppression of adult myogenesis, response character was compared between adult myogenic cells (Ad-cells) and larval tail myogenic cells (La-cells) to a Sonic hedgehog (Shh) inhibitor, notochord (Nc) cells, and spinal cord (SC) cells in vitro. Cyclopamine, an Shh inhibitor, suppressed the differentiation of cultured Ad (but not La) cells, suggesting the significance of Shh signaling in promoting adult myogenesis. To test the possibility that Shh-producing axial elements (notochord and spinal cord) regulate adult myogenesis, Ad-cells or La-cells were co-cultured with Nc or SC cells. The results showed that differentiation of Ad-cells were strongly inhibited by Nc cells but promoted by SC cells. If Ad-cells were "separately" co-cultured with Nc cells without direct cell-cell interactions, adult differentiation was not inhibited but rather promoted, suggesting that Nc cells have two roles, one is a short-range suppression and another is a long-range promotion for adult myogenesis. Immunohistochemical analysis showed both notochord and spinal cord express the N-terminal Shh fragment throughout metamorphosis. The "spinal cord-promotion" and long-range effect by Nc cells on adult myogenesis is thus involved in Shh signaling, while the signaling concerning the short-range "Nc suppression" will be determined by future studies. Interestingly, these effects, "Nc suppression" and "SC promotion" were not observed for La-cells. Situation where the spinal cord/notochord cross-sectional ratio is quite larger in tadpole trunk than in the tail seems to contribute to trunk-specific promotion and tail-specific suppression of adult myogenesis during Xenopus metamorphosis.

Efficacy of ivermectin as an anthelmintic in leopard frogs.

Science.gov (United States)

Letcher, J; Glade, M

1992-02-15

Ivermectin administered cutaneously at dosages of 2 mg/kg of body weight eliminated nematode infections in leopard frogs. Three clinical trials were conducted. In the first trial, 5 groups of 11 frogs were given ivermectin IM at dosages of 0, 0.2, 0.4, 2, or 20 mg/kg. All frogs given ivermectin IM at dosages of 2.0 mg/kg or greater died. In trial 2, 44 frogs, allotted to 5 groups, were given ivermectin cutaneously at 0, 0.2, 2, or 20 mg/kg. Cutaneously administered ivermectin was not toxic at dosages up to 20 mg/kg. In trial 3, nematode infections were eliminated in all 10 frogs treated cutaneously with ivermectin at 2.0 mg/kg.

CARE AND FEEDING OF FROGS

International Nuclear Information System (INIS)

Pan, Margaret; Chiang, Eugene

2012-01-01

'Propellers' are features in Saturn's A ring associated with moonlets that open partial gaps. They exhibit non-Keplerian motion (Tiscareno et al.); the longitude residuals of the best-observed propeller, 'Blériot', appear consistent with a sinusoid of period ∼4 years. Pan and Chiang proposed that propeller moonlets librate in 'frog resonances' with co-orbiting ring material. By analogy with the restricted three-body problem, they treated the co-orbital material as stationary in the rotating frame and neglected non-co-orbital material. Here we use simple numerical experiments to extend the frog model, including feedback due to the gap's motion, and drag associated with the Lindblad disk torques that cause Type I migration. Because the moonlet creates the gap, we expect the gap centroid to track the moonlet, but only after a time delay t delay , the time for a ring particle to travel from conjunction with the moonlet to the end of the gap. We find that frog librations can persist only if t delay exceeds the frog libration period P lib , and if damping from Lindblad torques balances driving from co-orbital torques. If t delay ib , then the libration amplitude damps to zero. In the case of Blériot, the frog resonance model can reproduce the observed libration period P lib ≅ 4 yr. However, our simple feedback prescription suggests that Blériot's t delay ∼ 0.01P lib , which is inconsistent with the observed libration amplitude of 260 km. We urge more accurate treatments of feedback to test the assumptions of our toy models.

Large intestine bacterial flora of nonhibernating and hibernating leopard frogs (Rana pipiens).

OpenAIRE

Gossling, J; Loesche, W J; Nace, G W

1982-01-01

The bacteria in the large intestines of 10 northern leopard frogs (Rana pipiens) were enumerated and partially characterized. Four nonhibernating frogs were collected in the summer, four hibernating frogs were collected in the winter, and two frogs just emerged from hibernation were collected in the spring. All frogs had about 10(10) bacteria per g (wet weight) of intestinal contents and about 10(9) bacteria per g (wet weight) of mucosal scraping, although the counts from the winter frogs wer...

THE MOCHE BOTANICAL FROG (La rana botánica mochica)

OpenAIRE

Donna McClelland †

2011-01-01

Plants and animals with features which identify them as supernaturals characterize the art of the Precolumbian Moche culture of northern Peru. Among these animals is a frog with feline attributes and a consistent association with manioc tubers, stalks, and plants, the Botanical Frog. The Botanical Frog appears to have been patterned on Leptodactylus pentadactylus. It is shown copulating with felines. Fine line painted vessels and ones with low relief decoration show the Botanical Frog perform...

Peatlands and green frogs: A relationship regulated by acidity?

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Mazerolle, M.J.

2005-01-01

The effects of site acidification on amphibian populations have been thoroughly addressed in the last decades. However, amphibians in naturally acidic environments, such as peatlands facing pressure from the peat mining industry, have received little attention. Through two field studies and an experiment, I assessed the use of bog habitats by the green frog (Rana clamitans melanota), a species sensitive to various forestry and peat mining disturbances. First, I compared the occurrence and breeding patterns of frogs in bog and upland ponds. I then evaluated frog movements between forest and bog habitats to determine whether they corresponded to breeding or postbreeding movements. Finally, I investigated, through a field experiment, the value of bogs as rehydrating areas for amphibians by offering living Sphagnum moss and two media associated with uplands (i.e., water with pH ca 6.5 and water-saturated soil) to acutely dehydrated frogs. Green frog reproduction at bog ponds was a rare event, and no net movements occurred between forest and bog habitats. However, acutely dehydrated frogs did not avoid Sphagnum. Results show that although green frogs rarely breed in bogs and do not move en masse between forest and bog habitats, they do not avoid bog substrates for rehydrating, despite their acidity. Thus, bogs offer viable summering habitat to amphibians, which highlights the value of these threatened environments in terrestrial amphibian ecology.

Calculating the Degradation Rate of Individual Proteins Using Xenopus Extract Systems.

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McDowell, Gary S; Philpott, Anna

2018-05-16

The Xenopus extract system has been used extensively as a simple, quick, and robust method for assessing the stability of proteins against proteasomal degradation. In this protocol, methods are provided for assessing the half-life of in vitro translated radiolabeled proteins using Xenopus egg or embryo extracts. © 2019 Cold Spring Harbor Laboratory Press.

Conservation and divergence of ADAM family proteins in the Xenopus genome

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Shah Anoop

2010-07-01

Full Text Available Abstract Background Members of the disintegrin metalloproteinase (ADAM family play important roles in cellular and developmental processes through their functions as proteases and/or binding partners for other proteins. The amphibian Xenopus has long been used as a model for early vertebrate development, but genome-wide analyses for large gene families were not possible until the recent completion of the X. tropicalis genome sequence and the availability of large scale expression sequence tag (EST databases. In this study we carried out a systematic analysis of the X. tropicalis genome and uncovered several interesting features of ADAM genes in this species. Results Based on the X. tropicalis genome sequence and EST databases, we identified Xenopus orthologues of mammalian ADAMs and obtained full-length cDNA clones for these genes. The deduced protein sequences, synteny and exon-intron boundaries are conserved between most human and X. tropicalis orthologues. The alternative splicing patterns of certain Xenopus ADAM genes, such as adams 22 and 28, are similar to those of their mammalian orthologues. However, we were unable to identify an orthologue for ADAM7 or 8. The Xenopus orthologue of ADAM15, an active metalloproteinase in mammals, does not contain the conserved zinc-binding motif and is hence considered proteolytically inactive. We also found evidence for gain of ADAM genes in Xenopus as compared to other species. There is a homologue of ADAM10 in Xenopus that is missing in most mammals. Furthermore, a single scaffold of X. tropicalis genome contains four genes encoding ADAM28 homologues, suggesting genome duplication in this region. Conclusions Our genome-wide analysis of ADAM genes in X. tropicalis revealed both conservation and evolutionary divergence of these genes in this amphibian species. On the one hand, all ADAMs implicated in normal development and health in other species are conserved in X. tropicalis. On the other hand, some

Differences in mobility at the range edge of an expanding invasive population of Xenopus laevis in the west of France.

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Louppe, Vivien; Courant, Julien; Herrel, Anthony

2017-01-15

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 individuals from two sites: one from the center and one from the periphery of an expanding population of the clawed frog Xenopus laevis in France where it was introduced about 30 years ago. Additionally, we provide data on the morphology of frogs from two additional sites to test whether the observed differences can be generalized across the range of this species in France. Given the known sexual size dimorphism in this species, we also test for differences between the sexes in locomotor performance and morphology. Our results show significant sexual dimorphism in stamina and morphology, with males having longer legs and greater stamina than females. Moreover, in accordance with the predictions from theoretical models, individuals from the range edge had a greater stamina. This difference in locomotor performance is likely to be driven by the significantly longer limb segments observed in animals in both sites sampled in different areas along the range edge. Our data have implications for conservation because spatial sorting on the range edge may lead to an accelerated increase in the spread of this invasive species in France. © 2017. Published by The Company of Biologists Ltd.

Xenopus pax6 mutants affect eye development and other organ systems, and have phenotypic similarities to human aniridia patients.

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Nakayama, Takuya; Fisher, Marilyn; Nakajima, Keisuke; Odeleye, Akinleye O; Zimmerman, Keith B; Fish, Margaret B; Yaoita, Yoshio; Chojnowski, Jena L; Lauderdale, James D; Netland, Peter A; Grainger, Robert M

2015-12-15

Mutations in the Pax6 gene cause ocular defects in both vertebrate and invertebrate animal species, and the disease aniridia in humans. Despite extensive experimentation on this gene in multiple species, including humans, we still do not understand the earliest effects on development mediated by this gene. This prompted us to develop pax6 mutant lines in Xenopus tropicalis taking advantage of the utility of the Xenopus system for examining early development and in addition to establish a model for studying the human disease aniridia in an accessible lower vertebrate. We have generated mutants in pax6 by using Transcription Activator-Like Effector Nuclease (TALEN) constructs for gene editing in X. tropicalis. Embryos with putative null mutations show severe eye abnormalities and changes in brain development, as assessed by changes in morphology and gene expression. One gene that we found is downregulated very early in development in these pax6 mutants is myc, a gene involved in pluripotency and progenitor cell maintenance and likely a mediator of some key pax6 functions in the embryo. Changes in gene expression in the developing brain and pancreas reflect other important functions of pax6 during development. In mutations with partial loss of pax6 function eye development is initially relatively normal but froglets show an underdeveloped iris, similar to the classic phenotype (aniridia) seen in human patients with PAX6 mutations. Other eye abnormalities observed in these froglets, including cataracts and corneal defects, are also common in human aniridia. The frog model thus allows us to examine the earliest deficits in eye formation as a result of pax6 lesions, and provides a useful model for understanding the developmental basis for the aniridia phenotype seen in humans. Copyright © 2015 Elsevier Inc. All rights reserved.

Doppler optical cardiogram gated 2D color flow imaging at 1000 fps and 4D in vivo visualization of embryonic heart at 45 fps on a swept source OCT system.

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Mariampillai, Adrian; Standish, Beau A; Munce, Nigel R; Randall, Cristina; Liu, George; Jiang, James Y; Cable, Alex E; Vitkin, I A; Yang, Victor X D

2007-02-19

We report a Doppler optical cardiogram gating technique for increasing the effective frame rate of Doppler optical coherence tomography (DOCT) when imaging periodic motion as found in the cardiovascular system of embryos. This was accomplished with a Thorlabs swept-source DOCT system that simultaneously acquired and displayed structural and Doppler images at 12 frames per second (fps). The gating technique allowed for ultra-high speed visualization of the blood flow pattern in the developing hearts of African clawed frog embryos (Xenopus laevis) at up to 1000 fps. In addition, four-dimensional (three spatial dimensions + temporal) Doppler imaging at 45 fps was demonstrated using this gating technique, producing detailed visualization of the complex cardiac motion and hemodynamics in a beating heart.

Courtship in Frogs

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education; Volume 1; Issue 12. Courtship in Frogs Role of Acoustic Communication in Amphibian Courtship Behaviour. Debjani Roy. General Article Volume 1 Issue 12 December 1996 pp 39-48 ...

Which frog's legs do froggies eat? The use of DNA barcoding for identification of deep frozen frog legs (Dicroglossidae, Amphibia commercialized in France

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Annemarie Ohler

2017-02-01

Full Text Available Several millions frogs captured in the wild in Indonesia are sold for food yearly in French supermarkets, as deep frozen frog legs. They are commercialized as Rana macrodon, but up to 15 look-alike species might also be concerned by this trade. From December 2012 to May 2013, we bought 209 specimens of deep frozen frog legs, and identified them through a barcoding approach based on the 16S gene. Our results show that 206 out of the 209 specimens belong to Fejervarya cancrivora, two to Limnonectes macrodon and one to F. moodiei. Thus only 0.96 % of the frogs were correctly identified. Unless misclassification was intentional, it seems that Indonesian frog leg exporters are not able to discriminate between the species. The quasi absence of L. macrodon in our samples might be an indication of its rarity, confirming that its natural populations are declining rapidly, in agreement with its “vulnerable” status according to the IUCN Red List. Our results show that the genetic and morphological diversity of the frogs in trade is much higher than the genetic and morphological diversity measured so far by scientific studies. These results underline the need for large scale studies to assess the status of wild populations.

IgE antibodies of fish allergic patients cross-react with frog parvalbumin.

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Hilger, C; Thill, L; Grigioni, F; Lehners, C; Falagiani, P; Ferrara, A; Romano, C; Stevens, W; Hentges, F

2004-06-01

The major allergens in fish are parvalbumins. Important immunoglobulin (Ig)E cross-recognition of parvalbumins from different fish species has been shown. Recently frog parvalbumin alpha has been found to be responsible for a case of IgE-mediated anaphylaxis triggered by the ingestion of frog meat. The aim of this study was to investigate whether IgE antibodies of fish allergic persons cross-react with frog parvalbumin and to appreciate its clinical relevance. The sera of 15 fish allergic patients and one fish and frog allergic patient were tested by IgE-immunoblotting against frog muscle extract. Sera were tested against recombinant parvalbumin alpha and beta from Rana esculenta. Skin prick tests were performed in selected patients with recombinant frog parvalbumin. Ca(2+) depletion experiments and inhibition studies with purified cod and frog recombinant parvalbumin were done to characterize the cross-reactive pattern. Fourteen of the sera tested had IgE antibodies recognizing low molecular weight components in frog muscle extract. Calcium depletion experiments or inhibition of patient sera with purified cod parvalbumin led to a significant or complete decrease in IgE binding. When tested against recombinant parvalbumins, three of 13 sera reacted with alpha parvalbumin and 11 of 12 reacted with beta parvalbumin from R. esculenta. Skin prick tests performed with recombinant frog parvalbumin were positive in fish allergic patients. Inhibition studies showed that a fish and frog allergic patient was primarily sensitized to fish parvalbumin. Cod parvalbumin, a major cross-reactive allergen among different fish species, shares IgE binding epitopes with frog parvalbumin. This in vitro cross-reactivity seems to be also clinically relevant. Parvalbumins probably represent a new family of cross-reactive allergens.

Daphnia magna and Xenopus laevis as in vivo models to probe toxicity and uptake of quantum dots functionalized with gH625

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Galdiero E

2017-04-01

Full Text Available Emilia Galdiero,1 Annarita Falanga,2 Antonietta Siciliano,1 Valeria Maselli,1 Marco Guida,1 Rosa Carotenuto,1 Margherita Tussellino,1 Lucia Lombardi,3 Giovanna Benvenuto,4 Stefania Galdiero2 1Department of Biology, 2Department of Pharmacy and CiRPEB, University of Naples Federico II, 3Department of Experimental Medicine, Second University of Naples, 4Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli, Italy Abstract: The use of quantum dots (QDs for nanomedicine is hampered by their potential toxicologic effects and difficulties with delivery into the cell interior. We accomplished an in vivo study exploiting Daphnia magna and Xenopus laevis to evaluate both toxicity and uptake of QDs coated with the membranotropic peptide gH625 derived from the glycoprotein H of herpes simplex virus and widely used for drug delivery studies. We evaluated and compared the effects of QDs and gH625-QDs on the survival, uptake, induction of several responsive pathways and genotoxicity in D. magna, and we found that QDs coating plays a key role. Moreover, studies on X. laevis embryos allowed to better understand their cell/tissue localization and delivery efficacy. X. laevis embryos raised in Frog Embryo Teratogenesis Assay-Xenopus containing QDs or gH625-QDs showed that both nanoparticles localized in the gills, lung and intestine, but they showed different distributions, indicating that the uptake of gH625-QDs was enhanced; the functionalized QDs had a significantly lower toxic effect on embryos’ survival and phenotypes. We observed that D. magna and X. laevis are useful in vivo models for toxicity and drug delivery studies. Keywords: membranotropic peptide, delivery, blood–brain barrier, nanoparticles, genotoxicity

OCT imaging of craniofacial anatomy in xenopus embryos (Conference Presentation)

Science.gov (United States)

Deniz, Engin; Jonas, Stephan M.; Griffin, John; Hooper, Michael C.; Choma, Michael A.; Khokha, Mustafa K.

2016-03-01

The etiology of craniofacial defects is incompletely understood. The ability to obtain large amounts of gene sequence data from families affected by craniofacial defects is opening up new ways to understand molecular genetic etiological factors. One important link between gene sequence data and clinical relevance is biological research into candidate genes and molecular pathways. We present our recent research using OCT as a nondestructive phenotyping modality of craniofacial morphology in Xenopus embryos, an important animal model for biological research in gene and pathway discovery. We define 2D and 3D scanning protocols for a standardized approach to craniofacial imaging in Xenopus embryos. We define standard views and planar reconstructions for visualizing normal anatomy and landmarks. We compare these views and reconstructions to traditional histopathology using alcian blue staining. In addition to being 3D, nondestructive, and having much faster throughout, OCT can identify craniofacial features that are lost during traditional histopathological preparation. We also identify quantitative morphometric parameters to define normative craniofacial anatomy. We also note that craniofacial and cardiac defects are not infrequently present in the same patient (e.g velocardiofacial syndrome). Given that OCT excels at certain aspects of cardiac imaging in Xenopus embryos, our work highlights the potential of using OCT and Xenopus to study molecular genetic factors that impact both cardiac and craniofacial development.

Ant and Mite Diversity Drives Toxin Variation in the Little Devil Poison Frog.

Science.gov (United States)

McGugan, Jenna R; Byrd, Gary D; Roland, Alexandre B; Caty, Stephanie N; Kabir, Nisha; Tapia, Elicio E; Trauger, Sunia A; Coloma, Luis A; O'Connell, Lauren A

2016-06-01

Poison frogs sequester chemical defenses from arthropod prey, although the details of how arthropod diversity contributes to variation in poison frog toxins remains unclear. We characterized skin alkaloid profiles in the Little Devil poison frog, Oophaga sylvatica (Dendrobatidae), across three populations in northwestern Ecuador. Using gas chromatography/mass spectrometry, we identified histrionicotoxins, 3,5- and 5,8-disubstituted indolizidines, decahydroquinolines, and lehmizidines as the primary alkaloid toxins in these O. sylvatica populations. Frog skin alkaloid composition varied along a geographical gradient following population distribution in a principal component analysis. We also characterized diversity in arthropods isolated from frog stomach contents and confirmed that O. sylvatica specialize on ants and mites. To test the hypothesis that poison frog toxin variability reflects species and chemical diversity in arthropod prey, we (1) used sequencing of cytochrome oxidase 1 to identify individual prey specimens, and (2) used liquid chromatography/mass spectrometry to chemically profile consumed ants and mites. We identified 45 ants and 9 mites in frog stomachs, including several undescribed species. We also showed that chemical profiles of consumed ants and mites cluster by frog population, suggesting different frog populations have access to chemically distinct prey. Finally, by comparing chemical profiles of frog skin and isolated prey items, we traced the arthropod source of four poison frog alkaloids, including 3,5- and 5,8-disubstituted indolizidines and a lehmizidine alkaloid. Together, the data show that toxin variability in O. sylvatica reflects chemical diversity in arthropod prey.

Frogs Call at a Higher Pitch in Traffic Noise

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Kirsten M. Parris

2009-06-01

Full Text Available Male frogs call to attract females for mating and to defend territories from rival males. Female frogs of some species prefer lower-pitched calls, which indicate larger, more experienced males. Acoustic interference occurs when background noise reduces the active distance or the distance over which an acoustic signal can be detected. Birds are known to call at a higher pitch or frequency in urban noise, decreasing acoustic interference from low-frequency noise. Using Bayesian linear regression, we investigated the effect of traffic noise on the pitch of advertisement calls in two species of frogs, the southern brown tree frog (Litoria ewingii and the common eastern froglet (Crinia signifera. We found evidence that L. ewingii calls at a higher pitch in traffic noise, with an average increase in dominant frequency of 4.1 Hz/dB of traffic noise, and a total effect size of 123 Hz. This frequency shift is smaller than that observed in birds, but is still large enough to be detected by conspecific frogs and confer a significant benefit to the caller. Mathematical modelling predicted a 24% increase in the active distance of a L. ewingii call in traffic noise with a frequency shift of this size. Crinia signifera may also call at a higher pitch in traffic noise, but more data are required to be confident of this effect. Because frog calls are innate rather than learned, the frequency shift demonstrated by L. ewingii may represent an evolutionary adaptation to noisy conditions. The phenomenon of frogs calling at a higher pitch in traffic noise could therefore constitute an intriguing trade-off between audibility and attractiveness to potential mates.

Elastic modulus of tree frog adhesive toe pads.

Science.gov (United States)

Barnes, W Jon P; Goodwyn, Pablo J Perez; Nokhbatolfoghahai, Mohsen; Gorb, Stanislav N

2011-10-01

Previous work using an atomic force microscope in nanoindenter mode indicated that the outer, 10- to 15-μm thick, keratinised layer of tree frog toe pads has a modulus of elasticity equivalent to silicone rubber (5-15 MPa) (Scholz et al. 2009), but gave no information on the physical properties of deeper structures. In this study, micro-indentation is used to measure the stiffness of whole toe pads of the tree frog, Litoria caerulea. We show here that tree frog toe pads are amongst the softest of biological structures (effective elastic modulus 4-25 kPa), and that they exhibit a gradient of stiffness, being stiffest on the outside. This stiffness gradient results from the presence of a dense network of capillaries lying beneath the pad epidermis, which probably has a shock absorbing function. Additionally, we compare the physical properties (elastic modulus, work of adhesion, pull-off force) of the toe pads of immature and adult frogs.

Panamanian frog species host unique skin bacterial communities

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Lisa K. Belden

2015-10-01

Full Text Available Vertebrates, including amphibians, host diverse symbiotic microbes that contribute to host disease resistance. Globally, and especially in montane tropical systems, many amphibian species are threatened by a chytrid fungus, Batrachochytrium dendrobatidis (Bd, that causes a lethal skin disease. Bd therefore may be a strong selective agent on the diversity and function of the microbial communities inhabiting amphibian skin. In Panamá, amphibian population declines and the spread of Bd have been tracked. In 2012, we completed a field survey in Panamá to examine frog skin microbiota in the context of Bd infection. We focused on three frog species and collected two skin swabs per frog from a total of 136 frogs across four sites that varied from west to east in the time since Bd arrival. One swab was used to assess bacterial community structure using 16S rRNA amplicon sequencing and to determine Bd infection status, and one was used to assess metabolite diversity, as the bacterial production of anti-fungal metabolites is an important disease resistance function. The skin microbiota of the three Panamanian frog species differed in OTU (operational taxonomic unit, ~bacterial species community composition and metabolite profiles, although the pattern was less strong for the metabolites. Comparisons between frog skin bacterial communities from Panamá and the US suggest broad similarities at the phylum level, but key differences at lower taxonomic levels. In our field survey in Panamá, across all four sites, only 35 individuals (~26% were Bd infected. There was no clustering of OTUs or metabolite profiles based on Bd infection status and no clear pattern of west-east changes in OTUs or metabolite profiles across the four sites. Overall, our field survey data suggest that different bacterial communities might be producing broadly similar sets of metabolites across frog hosts and sites. Community structure and function may not be as tightly coupled in

Biodiversity of frog haemoparasites from sub-tropical northern KwaZulu-Natal, South Africa

OpenAIRE

Edward C. Netherlands; Courtney A. Cook; Donnavan J.D. Kruger; Louis H. du Preez; Nico J. Smit

2015-01-01

Since South Africa boasts a high biodiversity of frog species, a multispecies haemoparasite survey was conducted by screening the blood from 29 species and 436 individual frogs. Frogs were collected at three localities in sub-tropical KwaZulu-Natal, a hotspot for frog diversity. Twenty per cent of the frogs were infected with at least one of five groups of parasites recorded. Intraerythrocytic parasites comprising Hepatozoon, Dactylosoma, and viral or bacterial organisms, as well as extracell...

Tourism and the Conservation of Critically Endangered Frogs

Science.gov (United States)

Morrison, Clare; Simpkins, Clay; Castley, J. Guy; Buckley, Ralf C.

2012-01-01

Protected areas are critical for the conservation of many threatened species. Despite this, many protected areas are acutely underfunded, which reduces their effectiveness significantly. Tourism is one mechanism to promote and fund conservation in protected areas, but there are few studies analyzing its tangible conservation outcomes for threatened species. This study uses the 415 IUCN critically endangered frog species to evaluate the contribution of protected area tourism revenue to conservation. Contributions were calculated for each species as the proportion of geographic range inside protected areas multiplied by the proportion of protected area revenues derived from tourism. Geographic ranges were determined from IUCN Extent of Occurrence maps. Almost 60% (239) of critically endangered frog species occur in protected areas. Higher proportions of total range are protected in Nearctic, Australasian and Afrotopical regions. Tourism contributions to protected area budgets ranged from 5–100%. These financial contributions are highest for developing countries in the Afrotropical, Indomalayan and Neotropical regions. Data for both geographic range and budget are available for 201 critically endangered frog species with proportional contributions from tourism to species protection ranging from 0.8–99%. Tourism's financial contributions to critically endangered frog species protection are highest in the Afrotropical region. This study uses a coarse measure but at the global scale it demonstrates that tourism has significant potential to contribute to global frog conservation efforts. PMID:22984440

Which frog's legs do froggies eat? The use of DNA barcoding for identification of deep frozen frog legs (Dicroglossidae, Amphibia) commercialized in France

OpenAIRE

Ohler, Annemarie; Nicolas, Violaine

2017-01-01

International audience; Several millions frogs captured in the wild in Indonesia are sold for food yearly in French supermarkets, as deep frozen frog legs. They are commercialized as Rana macrodon, but up to 15 look-alike species might also be concerned by this trade. From December 2012 to May 2013, we bought 209 specimens of deep frozen frog legs, and identified them through a barcoding approach based on the 16S gene. Our results show that 206 out of the 209 specimens belong to Fejervarya ca...

EBF proteins participate in transcriptional regulation of Xenopus muscle development.

Science.gov (United States)

Green, Yangsook Song; Vetter, Monica L

2011-10-01

EBF proteins have diverse functions in the development of multiple lineages, including neurons, B cells and adipocytes. During Drosophila muscle development EBF proteins are expressed in muscle progenitors and are required for muscle cell differentiation, but there is no known function of EBF proteins in vertebrate muscle development. In this study, we examine the expression of ebf genes in Xenopus muscle tissue and show that EBF activity is necessary for aspects of Xenopus skeletal muscle development, including somite organization, migration of hypaxial muscle anlagen toward the ventral abdomen, and development of jaw muscle. From a microarray screen, we have identified multiple candidate targets of EBF activity with known roles in muscle development. The candidate targets we have verified are MYOD, MYF5, M-Cadherin and SEB-4. In vivo overexpression of the ebf2 and ebf3 genes leads to ectopic expression of these candidate targets, and knockdown of EBF activity causes downregulation of the endogenous expression of the candidate targets. Furthermore, we found that MYOD and MYF5 are likely to be direct targets. Finally we show that MYOD can upregulate the expression of ebf genes, indicating the presence of a positive feedback loop between EBF and MYOD that we find to be important for maintenance of MYOD expression in Xenopus. These results suggest that EBF activity is important for both stabilizing commitment and driving aspects of differentiation in Xenopus muscle cells. Copyright © 2010 Elsevier Inc. All rights reserved.

Gene expression analysis of the ovary of hybrid females of Xenopus laevis and X. muelleri

Directory of Open Access Journals (Sweden)

Malone John H

2008-03-01

Full Text Available Abstract Background Interspecific hybrids of frogs of the genus Xenopus result in sterile hybrid males and fertile hybrid females. Previous work has demonstrated a dramatic asymmetrical pattern of misexpression in hybrid males compared to the two parental species with relatively few genes misexpressed in comparisons of hybrids and the maternal species (X. laevis and dramatically more genes misexpressed in hybrids compared to the paternal species (X. muelleri. In this work, we examine the gene expression pattern in hybrid females of X. laevis × X. muelleri to determine if this asymmetrical pattern of expression also occurs in hybrid females. Results We find a similar pattern of asymmetry in expression compared to males in that there were more genes differentially expressed between hybrids and X. muelleri compared to hybrids and X. laevis. We also found a dramatic increase in the number of misexpressed genes with hybrid females having about 20 times more genes misexpressed in ovaries compared to testes of hybrid males and therefore the match between phenotype and expression pattern is not supported. Conclusion We discuss these intriguing findings in the context of reproductive isolation and suggest that divergence in female expression may be involved in sterility of hybrid males due to the inherent sensitivity of spermatogenesis as defined by the faster male evolution hypothesis for Haldane's rule.

Potential protective effect of L-cysteine against the toxicity of acrylamide and furan in exposed Xenopus laevis embryos: an interaction study.

Science.gov (United States)

Williams, John Russell; Rayburn, James R; Cline, George R; Sauterer, Roger; Friedman, Mendel

2014-08-06

The embryo toxicities of two food-processing-induced toxic compounds, acrylamide and furan, with and without added L-cysteine were examined individually and in mixtures using the frog embryo teratogenesis assay-Xenopus (FETAX). The following measures of developmental toxicity were used: (a) 96 h LC50, the median concentration causing 50% embryo lethality; (b) 96 h EC50, the median concentration causing 50% malformations of the surviving embryos; and (c) teratogenic index (96 h LC50/96 h EC50), an estimate of teratogenic risk. Calculations of toxic units (TU) were used to assess possible antagonism, synergism, or response addition of several mixtures. The evaluated compounds demonstrated counterintuitive effects. Furan had lower than expected toxicity in Xenopus embryos and, unlike acrylamide, does not seem to be teratogenic. However, the short duration of the tests may not show the full effects of furan if it is truly primarily genotoxic and carcinogenic. L-Cysteine showed unexpected properties in the delay of hatching of the embryos. The results from the interaction studies between combination of two or three components (acrylamide plus L-cysteine; furan plus L-cysteine; acrylamide plus furan; acrylamide plus furan and L-cysteine) show that furan and acrylamide seem to have less than response addition at 1:1 toxic unit ratio in lethality. Acrylamide and L-cysteine show severe antagonism even at low 19 acrylamide/1 L-cysteine TU ratios. Data from the mixture of acrylamide, furan, and L-cysteine show a slight antagonism, less than would have been expected from binary mixture exposures. Bioalkylation mechanisms and their prevention are discussed. There is a need to study the toxicological properties of mixtures of acrylamide and furan concurrently formed in heat-processed food.

Neuromuscular control of prey capture in frogs.

OpenAIRE

Nishikawa, K C

1999-01-01

While retaining a feeding apparatus that is surprisingly conservative morphologically, frogs as a group exhibit great variability in the biomechanics of tongue protraction during prey capture, which in turn is related to differences in neuromuscular control. In this paper, I address the following three questions. (1) How do frog tongues differ biomechanically? (2) What anatomical and physiological differences are responsible? (3) How is biomechanics related to mechanisms of neuromuscular cont...

Isolation of Brucella inopinata-Like Bacteria from White's and Denny's Tree Frogs.

Science.gov (United States)

Kimura, Masanobu; Une, Yumi; Suzuki, Michio; Park, Eun-Sil; Imaoka, Koichi; Morikawa, Shigeru

2017-05-01

Brucella inopinata strain BO1 and B. sp. strain BO2 isolated from human patients, respectively, are genetically different from classical Brucella species. We isolated bacteria of the genus Brucella from two species of wild-caught tropical frogs kept in the facilities in Japan: White's tree frog, which inhabits Oceania, and Denny's tree frog, which inhabits Southeast Asia. Phylogenetic analyses based on 16S rRNA and recA gene sequences and multilocus sequence analysis showed that two isolates of Brucella spp. showed significant similarity to BO1, BO2, and the isolates from other wild-caught frogs. These results suggest that a variety of frog species are susceptible to a novel clade of Brucella bacteria, including B. inopinata.

Regulation of Xenopus laevis DNA topoisomerase I activity by phosphorylation in vitro

International Nuclear Information System (INIS)

Kaiserman, H.B.; Ingebritsen, T.S.; Benbow, R.M.

1988-01-01

DNA topoisomerase I has been purified to electrophoretic homogeneity from ovaries of the frog Xenopus laevis. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the most purified fraction revealed a single major band at 110 kDa and less abundant minor bands centered at 62 kDa. Incubation of the most purified fraction with immobilized calf intestinal alkaline phosphatase abolished all DNA topoisomerase enzymatic activity in a time-dependent reaction. Treatment of the dephosphorylated X. laevis DNA topoisomerase I with a X. laevis casein kinase type II activity and ATP restored DNA topoisomerase activity to a level higher than that observed in the most purified fraction. In vitro labeling experiments which employed the most purified DNA topoisomerase I fraction, [γ- 32 P]ATP, and the casein kinase type II enzyme showed that both the 110- and 62-kDa bands became phosphorylated in approximately molar proportions. Phosphoamino acid analysis showed that only serine residues became phosphorylated. Phosphorylation was accompanied by an increase in DNA topoisomerase activity in vitro. Dephosphorylation of DNA topoisomerase I appears to block formation of the initial enzyme-substrate complex on the basis of the failure of the dephosphorylated enzyme to nick DNA in the presence of camptothecin. The authors conclude that X. laevis DNA topoisomerase I is partially phosphorylated as isolated and that this phosphorylation is essential for expression of enzymatic activity in vitro. On the basis of the ability of the casein kinase type II activity to reactivate dephosphorylated DNA topoisomerase I, they speculate that this kinase may contribute to the physiological regulation of DNA topoisomerase I activity

FROG: The Fast And Realistic OpenGL Event Displayer

CERN Document Server

Quertenmont, Loic

2009-01-01

FROG [1] [2] is a generic framework dedicated to visualisation of events in high energy experiment. It is suitable to any particular physics experiment or detector design. The code is light (< 3 MB) and fast (browsing time 20 events per second for a large High Energy Physics experiment) and can run on various operating systems, as its object-oriented structure (C++) relies on the cross-platform OPENGL [3] and GLUT [4] libraries. Moreover, FROG does not require installation of third party libraries for the visualisation. This documents describes the features and principles of FROG version 1.106, its working scheme and numerous functionalities such as: 3D and 2D visualisation, graphical user interface, mouse interface, configuration files, production of pictures of various format, integration of personal objects, etc. Finally the application of FROG for physic experiment/environement, such as Gastof, CMS, ILD, Delphes will be presented for illustration.

Courtship in Frogs

Indian Academy of Sciences (India)

well-defined physical characteristics and a clear biological meaning. ... men t most successfully were the frogs and toads (hereafter referred ... Sound Pressure Level (SPL) in decibels = 20 loglOPt/Pr where,. Pt is the .... R.erythraea (left) and mean spectrum and sonagram of the female ... and egg laying activities initiated. 5.

Distribution, structure and projections of the frog intracardiac neurons.

Science.gov (United States)

Batulevicius, Darius; Skripkiene, Gertruda; Batuleviciene, Vaida; Skripka, Valdas; Dabuzinskiene, Anita; Pauza, Dainius H

2012-05-21

Histochemistry for acetylcholinesterase was used to determine the distribution of intracardiac neurons in the frog Rana temporaria. Seventy-nine intracardiac neurons from 13 frogs were labelled iontophoretically by the intracellular markers Alexa Fluor 568 and Lucifer Yellow CH to determine their structure and projections. Total neuronal number per frog heart was (Mean ± SE) 1374 ± 56. Largest collections of neurons were found in the interatrial septum (46%), atrioventricular junction (25%) and venal sinus (12%). Among the intracellularly labelled neurons, we found the cells of unipolar (71%), multipolar (20%) and bipolar (9%) types. Multiple processes originated from the neuron soma, hillock and proximal axon. These processes projected onto adjacent neuron somata and cardiac muscle fibers within the interatrial septum. Average total length of the processes from proximal axon was 348 ± 50 μm. Average total length of processes from soma and hillock was less, 118 ± 27 μm and 109 ± 24 μm, respectively. The somata of 59% of neurons had bubble- or flake-shaped extensions. Most neurons from the major nerves in the interatrial septum sent their axons towards the ventricle. In contrast, most neurons from the ventral part of the interatrial septum sent their axons towards the atria. Our findings contradict to a view that the frog intracardiac ganglia contain only non-dendritic neurons of the unipolar type. We conclude that the frog intracardiac neurons are structurally complex and diverse. This diversity may account for the complicated integrative functions of the frog intrinsic cardiac ganglia. Copyright © 2012 Elsevier B.V. All rights reserved.

Plasticity of peripheral auditory frequency sensitivity in Emei music frog.

Science.gov (United States)

Zhang, Dian; Cui, Jianguo; Tang, Yezhong

2012-01-01

In anurans reproductive behavior is strongly seasonal. During the spring, frogs emerge from hibernation and males vocalize for mating or advertising territories. Female frogs have the ability to evaluate the quality of the males' resources on the basis of these vocalizations. Although studies revealed that central single torus semicircularis neurons in frogs exhibit season plasticity, the plasticity of peripheral auditory sensitivity in frog is unknown. In this study the seasonally plasticity of peripheral auditory sensitivity was test in the Emei music frog Babina daunchina, by comparing thresholds and latencies of auditory brainstem responses (ABRs) evoked by tone pips and clicks in the reproductive and non-reproductive seasons. The results show that both ABR thresholds and latency differ significantly between the reproductive and non-reproductive seasons. The thresholds of tone pip evoked ABRs in the non-reproductive season increased significantly about 10 dB than those in the reproductive season for frequencies from 1 KHz to 6 KHz. ABR latencies to waveform valley values for tone pips for the same frequencies using appropriate threshold stimulus levels are longer than those in the reproductive season for frequencies from 1.5 to 6 KHz range, although from 0.2 to 1.5 KHz range it is shorter in the non-reproductive season. These results demonstrated that peripheral auditory frequency sensitivity exhibits seasonal plasticity changes which may be adaptive to seasonal reproductive behavior in frogs.

The ribosome biogenesis factor Nol11 is required for optimal rDNA transcription and craniofacial development in Xenopus.

Directory of Open Access Journals (Sweden)

John N Griffin

2015-03-01

Full Text Available The production of ribosomes is ubiquitous and fundamental to life. As such, it is surprising that defects in ribosome biogenesis underlie a growing number of symptomatically distinct inherited disorders, collectively called ribosomopathies. We previously determined that the nucleolar protein, NOL11, is essential for optimal pre-rRNA transcription and processing in human tissue culture cells. However, the role of NOL11 in the development of a multicellular organism remains unknown. Here, we reveal a critical function for NOL11 in vertebrate ribosome biogenesis and craniofacial development. Nol11 is strongly expressed in the developing cranial neural crest (CNC of both amphibians and mammals, and knockdown of Xenopus nol11 results in impaired pre-rRNA transcription and processing, increased apoptosis, and abnormal development of the craniofacial cartilages. Inhibition of p53 rescues this skeletal phenotype, but not the underlying ribosome biogenesis defect, demonstrating an evolutionarily conserved control mechanism through which ribosome-impaired craniofacial cells are removed. Excessive activation of this mechanism impairs craniofacial development. Together, our findings reveal a novel requirement for Nol11 in craniofacial development, present the first frog model of a ribosomopathy, and provide further insight into the clinically important relationship between specific ribosome biogenesis proteins and craniofacial cell survival.

Poison frog colors are honest signals of toxicity, particularly for bird predators.

Science.gov (United States)

Maan, Martine E; Cummings, Molly E

2012-01-01

Antipredator defenses and warning signals typically evolve in concert. However, the extensive variation across taxa in both these components of predator deterrence and the relationship between them are poorly understood. Here we test whether there is a predictive relationship between visual conspicuousness and toxicity levels across 10 populations of the color-polymorphic strawberry poison frog, Dendrobates pumilio. Using a mouse-based toxicity assay, we find extreme variation in toxicity between frog populations. This variation is significantly positively correlated with frog coloration brightness, a viewer-independent measure of visual conspicuousness (i.e., total reflectance flux). We also examine conspicuousness from the view of three potential predator taxa, as well as conspecific frogs, using taxon-specific visual detection models and three natural background substrates. We find very strong positive relationships between frog toxicity and conspicuousness for bird-specific perceptual models. Weaker but still positive correlations are found for crab and D. pumilio conspecific visual perception, while frog coloration as viewed by snakes is not related to toxicity. These results suggest that poison frog colors can be honest signals of prey unpalatability to predators and that birds in particular may exert selection on aposematic signal design. © 2011 by The University of Chicago.

Frog species richness, composition and beta-diversity in coastal Brazilian restinga habitats.

Science.gov (United States)

Rocha, C F D; Hatano, F H; Vrcibradic, D; Van Sluys, M

2008-02-01

We studied the species richness and composition of frogs in 10 restinga habitats (sand dune environments dominated by herbaceous and shrubby vegetation) along approximately 1500 km of coastal areas of three Brazilian States: Rio de Janeiro (Grumari, Maricá, Massambaba, Jurubatiba and Grussaí), Espírito Santo (Praia das Neves and Setiba) and Bahia (Prado and Trancoso). We estimated beta-diversity and similarity among areas and related these parameters to geographic distance between areas. All areas were surveyed with a similar sampling procedure. We found 28 frog species belonging to the families Hylidae, Microhylidae, Leptodactylidae and Bufonidae. Frogs in restingas were in general nocturnal with no strictly diurnal species. The richest restinga was Praia das Neves (13 species), followed by Grussaí and Trancoso (eight species in each). The commonest species in the restingas was Scinax alter (found in eight restingas), followed by Aparasphenodon brunoi (seven areas). Our data shows that richness and composition of frog communities vary consistently along the eastern Brazilian coast and, in part, the rate of species turnover is affected by the distance among areas. Geographic distance explained approximately 12% of species turnover in restingas and about 9.5% of similarity among frog assemblages. Although geographic distance somewhat affects frog assemblages, other factors (e.g. historical factors, disturbances) seem to be also involved in explaining present frog assemblage composition in each area and species turnover among areas. The frog fauna along restinga habitats was significantly nested (matrix community temperature = 26.13 degrees; p = 0.007). Our data also showed that the most hospitable restinga was Praia das Neves and indicated that this area should be protected as a conservation unit. Frog assemblage of each area seems to partially represent a nested subset of the original assemblage, although we should not ignore the importance of historical

Life Histories of Frogs in the Namib Desert | Channing | African ...

African Journals Online (AJOL)

African Zoology. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 11, No 2 (1976) >. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Download this PDF file. The PDF file you selected should load here if your ...

Reel Royal Diversity? The Glass Ceiling in Disney’s Mulan and Princess and the Frog

Directory of Open Access Journals (Sweden)

Lauren Dundes

2016-12-01

Full Text Available Both in Mulan and Princess and the Frog, Disney eschews a traditional fairytale ending involving palatial opulence by substituting an alternative narrative for women of color. Mulan disguises herself as a male soldier in order to serve in her father’s place. After sharing victory with male companions, she willingly returns home to domesticity and the confines imposed by her gender. Tiana spends two thirds of the movie as a frog, substantially limiting her on-screen time as an African American female. Like Mulan, she is driven to please her father. She fulfills his dream of owning a high-end restaurant, ironically named Tiana’s Palace, the closest she comes to a royal lifestyle. Although protagonists with more realistic lives could potentially enhance viewers’ connection with them and model a work ethic or commitment to home life, the standard and more financially successful Disney narrative immerses viewers in a fantasy world of endless prospects including a life of royalty. These nonwhite heroines instead display a willingness to settle for more modest aspirations in stories replete with stereotypical gender and race-bound tropes. This divergent narrative suggests that protagonists of color are not entitled to a life of leisure and privilege that white Disney princesses enjoy.

Modeling potential river management conflicts between frogs and salmonids

Science.gov (United States)

Steven F. Railsback; Bret C. Harvey; Sarah J. Kupferberg; Margaret M. Lang; Scott McBain; Hart H. Welsh

2016-01-01

Management of regulated rivers for yellow-legged frogs (Rana boylii) and salmonids exemplifies potential conflicts among species adapted to different parts of the natural flow and temperature regimes. Yellow-legged frogs oviposit in rivers in spring and depend on declining flows and warming temperatures for egg and tadpole survival and growth,...

Plasticity of peripheral auditory frequency sensitivity in Emei music frog.

Directory of Open Access Journals (Sweden)

Dian Zhang

Full Text Available In anurans reproductive behavior is strongly seasonal. During the spring, frogs emerge from hibernation and males vocalize for mating or advertising territories. Female frogs have the ability to evaluate the quality of the males' resources on the basis of these vocalizations. Although studies revealed that central single torus semicircularis neurons in frogs exhibit season plasticity, the plasticity of peripheral auditory sensitivity in frog is unknown. In this study the seasonally plasticity of peripheral auditory sensitivity was test in the Emei music frog Babina daunchina, by comparing thresholds and latencies of auditory brainstem responses (ABRs evoked by tone pips and clicks in the reproductive and non-reproductive seasons. The results show that both ABR thresholds and latency differ significantly between the reproductive and non-reproductive seasons. The thresholds of tone pip evoked ABRs in the non-reproductive season increased significantly about 10 dB than those in the reproductive season for frequencies from 1 KHz to 6 KHz. ABR latencies to waveform valley values for tone pips for the same frequencies using appropriate threshold stimulus levels are longer than those in the reproductive season for frequencies from 1.5 to 6 KHz range, although from 0.2 to 1.5 KHz range it is shorter in the non-reproductive season. These results demonstrated that peripheral auditory frequency sensitivity exhibits seasonal plasticity changes which may be adaptive to seasonal reproductive behavior in frogs.

Frog sound identification using extended k-nearest neighbor classifier

Science.gov (United States)

Mukahar, Nordiana; Affendi Rosdi, Bakhtiar; Athiar Ramli, Dzati; Jaafar, Haryati

2017-09-01

Frog sound identification based on the vocalization becomes important for biological research and environmental monitoring. As a result, different types of feature extractions and classifiers have been employed to evaluate the accuracy of frog sound identification. This paper presents a frog sound identification with Extended k-Nearest Neighbor (EKNN) classifier. The EKNN classifier integrates the nearest neighbors and mutual sharing of neighborhood concepts, with the aims of improving the classification performance. It makes a prediction based on who are the nearest neighbors of the testing sample and who consider the testing sample as their nearest neighbors. In order to evaluate the classification performance in frog sound identification, the EKNN classifier is compared with competing classifier, k -Nearest Neighbor (KNN), Fuzzy k -Nearest Neighbor (FKNN) k - General Nearest Neighbor (KGNN)and Mutual k -Nearest Neighbor (MKNN) on the recorded sounds of 15 frog species obtained in Malaysia forest. The recorded sounds have been segmented using Short Time Energy and Short Time Average Zero Crossing Rate (STE+STAZCR), sinusoidal modeling (SM), manual and the combination of Energy (E) and Zero Crossing Rate (ZCR) (E+ZCR) while the features are extracted by Mel Frequency Cepstrum Coefficient (MFCC). The experimental results have shown that the EKNCN classifier exhibits the best performance in terms of accuracy compared to the competing classifiers, KNN, FKNN, GKNN and MKNN for all cases.

Biogeographic patterns of Colombian frogs and toads

International Nuclear Information System (INIS)

Lynch, John D.; Ruiz Carranza, Pedro M; Ardila Robayo, Maria Cristina

1997-01-01

Using the data provided in Ruiz-Carranza et al. (1996) the distributions of the 540 species of frogs and toads are partitioned among ten ecogeographic units of Colombia defined on the basis of precipitation and elevation. Some lowlands areas (pacific lowlands, Amazonian) exhibit high diversity (85-94 species) but lowlands areas in general are impoverished (30-52 species), especially when contrasted with upland areas. The three Andean cordilleras harbor between 87 and 121 species of frogs and toads, demonstrating that the biodiversity of Colombia resides primarily in its montane components, not in its lowland rain forests. When biological endemicity is separated from political endemicity, five areas of high endemicity remain (the three Andean cordilleras, the Sierra Nevada de Santa Marta, and the pacific lowlands). We endeavor to explain this description by recourse to cladistic analyses of several groups of leptodactylid frogs where we find that the general pattern of diversification is by means of horizontal diversification (allopatric speciation) with a minor contribution from vertical diversification

Parasites of the mink frog (rana septentrionalis) from Minnesota, U.S.A.

Science.gov (United States)

Schotthoefer, Anna M.; Bolek, M.G.; Cole, Rebecca A.; Beasley, Val R.

2009-01-01

Twenty-two mink frogs, Rana septentrionalis, collected from two locations in Minnesota, United States, were examined for helminth and protozoan blood parasites in July 1999. A total of 16 parasite taxa were recovered including 5 larval digenean trematodes, 7 adult digenean trematodes, 3 nematodes, and I Trypanosorna species. Infracommunities were dominated by the digeneans in terms of richness and abundance. In particular, echinostomatid metacercariae in the kidneys of frogs were the most common parasites found, infecting 100% of the frogs and consisting of about 90% of all helminth individuals recovered. Gorgodera amplicava, Gorgoderina multilohata, Haernaroloechus pan'iplexus, Haernatoloechus breviplexus, Cosnwcercoides dukae, and Oswaldocruzia pipiens represent new host records. The survey presented here represents the second known helminth survey of mink frogs conducted in North America. A summary of metazoan parasites reported from mink frogs is included.

Derived (mutated)-types of TRPV6 channels elicit greater Ca²+ influx into the cells than ancestral-types of TRPV6: evidence from Xenopus oocytes and mammalian cell expression system.

Science.gov (United States)

Sudo, Yuka; Matsuo, Kiyotaka; Tetsuo, Tomoyuki; Tsutsumi, Satoshi; Ohkura, Masamichi; Nakai, Junichi; Uezono, Yasuhito

2010-01-01

The frequency of the allele containing three derived nonsynonymous SNPs (157C, 378M, 681M) of the gene encoding calcium permeable TRPV6 channels expressed in the intestine has been increased by positive selection in non-African populations. To understand the nature of these SNPs, we compared the properties of Ca²+ influx of ancestral (in African populations) and derived-TRPV6 (in non-African populations) channels with electrophysiological, Ca²+-imaging, and morphological methods using both the Xenopus oocyte and mammalian cell expression systems. Functional electrophysiological and Ca²+-imaging analyses indicated that the derived-TRPV6 elicited more Ca²+ influx than the ancestral one in TRPV6-expressing cells where both channels were equally expressed in the cells. Ca²+-inactivation properties in the ancestral- and derived-TRPV6 were almost the same. Furthermore, fluorescence resonance energy transfer (FRET) analysis showed that both channels have similar multimeric formation properties, suggesting that derived-TRPV6 itself could cause higher Ca²+ influx. These findings suggest that populations having derived-TRPV6 in non-African areas may absorb higher Ca²+ from the intestine than ancestral-TRPV6 in the African area.

Analysis of neural progenitors from embryogenesis to juvenile adult in Xenopus laevis reveals biphasic neurogenesis and continuous lengthening of the cell cycle

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Raphaël Thuret

2015-12-01

Full Text Available Xenopus laevis is a prominent model system for studying neural development, but our understanding of the long-term temporal dynamics of neurogenesis remains incomplete. Here, we present the first continuous description of neurogenesis in X. laevis, covering the entire period of development from the specification of neural ectoderm during gastrulation to juvenile frog. We have used molecular markers to identify progenitors and neurons, short-term bromodeoxyuridine (BrdU incorporation to map the generation of newborn neurons and dual pulse S-phase labelling to characterise changes in their cell cycle length. Our study revealed the persistence of Sox3-positive progenitor cells from the earliest stages of neural development through to the juvenile adult. Two periods of intense neuronal generation were observed, confirming the existence of primary and secondary waves of neurogenesis, punctuated by a period of quiescence before metamorphosis and culminating in another period of quiescence in the young adult. Analysis of multiple parameters indicates that neural progenitors alternate between global phases of differentiation and amplification and that, regardless of their behaviour, their cell cycle lengthens monotonically during development, at least at the population level.

Frog species richness, composition and beta-diversity in coastal Brazilian restinga habitats

Directory of Open Access Journals (Sweden)

CFD. Rocha

Full Text Available We studied the species richness and composition of frogs in 10 restinga habitats (sand dune environments dominated by herbaceous and shrubby vegetation along approximately 1500 km of coastal areas of three Brazilian States: Rio de Janeiro (Grumari, Maricá, Massambaba, Jurubatiba and Grussaí, Espírito Santo (Praia das Neves and Setiba and Bahia (Prado and Trancoso. We estimated beta-diversity and similarity among areas and related these parameters to geographic distance between areas. All areas were surveyed with a similar sampling procedure. We found 28 frog species belonging to the families Hylidae, Microhylidae, Leptodactylidae and Bufonidae. Frogs in restingas were in general nocturnal with no strictly diurnal species. The richest restinga was Praia das Neves (13 species, followed by Grussaí and Trancoso (eight species in each. The commonest species in the restingas was Scinax alter (found in eight restingas, followed by Aparasphenodon brunoi (seven areas. Our data shows that richness and composition of frog communities vary consistently along the eastern Brazilian coast and, in part, the rate of species turnover is affected by the distance among areas. Geographic distance explained approximately 12% of species turnover in restingas and about 9.5% of similarity among frog assemblages. Although geographic distance somewhat affects frog assemblages, other factors (e.g. historical factors, disturbances seem to be also involved in explaining present frog assemblage composition in each area and species turnover among areas. The frog fauna along restinga habitats was significantly nested (matrix community temperature = 26.13°; p = 0.007. Our data also showed that the most hospitable restinga was Praia das Neves and indicated that this area should be protected as a conservation unit. Frog assemblage of each area seems to partially represent a nested subset of the original assemblage, although we should not ignore the importance of historical

Propulsive efficiency of frog swimming with different feet and swimming patterns

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Fan Jizhuang

2017-04-01

Full Text Available Aquatic and terrestrial animals have different swimming performances and mechanical efficiencies based on their different swimming methods. To explore propulsion in swimming frogs, this study calculated mechanical efficiencies based on data describing aquatic and terrestrial webbed-foot shapes and swimming patterns. First, a simplified frog model and dynamic equation were established, and hydrodynamic forces on the foot were computed according to computational fluid dynamic calculations. Then, a two-link mechanism was used to stand in for the diverse and complicated hind legs found in different frog species, in order to simplify the input work calculation. Joint torques were derived based on the virtual work principle to compute the efficiency of foot propulsion. Finally, two feet and swimming patterns were combined to compute propulsive efficiency. The aquatic frog demonstrated a propulsive efficiency (43.11% between those of drag-based and lift-based propulsions, while the terrestrial frog efficiency (29.58% fell within the range of drag-based propulsion. The results illustrate the main factor of swimming patterns for swimming performance and efficiency.

Xenopus egg extract: A powerful tool to study genome maintenance mechanisms.

Science.gov (United States)

Hoogenboom, Wouter S; Klein Douwel, Daisy; Knipscheer, Puck

2017-08-15

DNA repair pathways are crucial to maintain the integrity of our genome and prevent genetic diseases such as cancer. There are many different types of DNA damage and specific DNA repair mechanisms have evolved to deal with these lesions. In addition to these repair pathways there is an extensive signaling network that regulates processes important for repair, such as cell cycle control and transcription. Despite extensive research, DNA damage repair and signaling are not fully understood. In vitro systems such as the Xenopus egg extract system, have played, and still play, an important role in deciphering the molecular details of these processes. Xenopus laevis egg extracts contain all factors required to efficiently perform DNA repair outside a cell, using mechanisms conserved in humans. These extracts have been used to study several genome maintenance pathways, including mismatch repair, non-homologous end joining, ICL repair, DNA damage checkpoint activation, and replication fork stability. Here we describe how the Xenopus egg extract system, in combination with specifically designed DNA templates, contributed to our detailed understanding of these pathways. Copyright © 2017. Published by Elsevier Inc.

Do Nanoparticle Physico-Chemical Properties and Developmental Exposure Window Influence Nano ZnO Embryotoxicity in Xenopus laevis?

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Patrizia Bonfanti

2015-07-01

Full Text Available The growing global production of zinc oxide nanoparticles (ZnONPs suggests a realistic increase in the environmental exposure to such a nanomaterial, making the knowledge of its biological reactivity and its safe-by-design synthesis mandatory. In this study, the embryotoxicity of ZnONPs (1–100 mg/L specifically synthesized for industrial purposes with different sizes, shapes (round, rod and surface coatings (PEG, PVP was tested using the frog embryo teratogenesis assay-Xenopus (FETAX to identify potential target tissues and the most sensitive developmental stages. The ZnONPs did not cause embryolethality, but induced a high incidence of malformations, in particular misfolded gut and abdominal edema. Smaller, round NPs were more effective than the bigger, rod ones, and PEGylation determined a reduction in embryotoxicity. Ingestion appeared to be the most relevant exposure route. Only the embryos exposed from the stomodeum opening showed anatomical and histological lesions to the intestine, mainly referable to a swelling of paracellular spaces among enterocytes. In conclusion, ZnONPs differing in shape and surface coating displayed similar toxicity in X. laevis embryos and shared the same target organ. Nevertheless, we cannot exclude that the physico-chemical characteristics may influence the severity of such effects. Further research efforts are mandatory to ensure the synthesis of safer nano-ZnO-containing products.

Introducing the Forensic Research/Reference on Genetics knowledge base, FROG-kb.

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Rajeevan, Haseena; Soundararajan, Usha; Pakstis, Andrew J; Kidd, Kenneth K

2012-09-01

Online tools and databases based on multi-allelic short tandem repeat polymorphisms (STRPs) are actively used in forensic teaching, research, and investigations. The Fst value of each CODIS marker tends to be low across the populations of the world and most populations typically have all the common STRP alleles present diminishing the ability of these systems to discriminate ethnicity. Recently, considerable research is being conducted on single nucleotide polymorphisms (SNPs) to be considered for human identification and description. However, online tools and databases that can be used for forensic research and investigation are limited. The back end DBMS (Database Management System) for FROG-kb is Oracle version 10. The front end is implemented with specific code using technologies such as Java, Java Servlet, JSP, JQuery, and GoogleCharts. We present an open access web application, FROG-kb (Forensic Research/Reference on Genetics-knowledge base, http://frog.med.yale.edu), that is useful for teaching and research relevant to forensics and can serve as a tool facilitating forensic practice. The underlying data for FROG-kb are provided by the already extensively used and referenced ALlele FREquency Database, ALFRED (http://alfred.med.yale.edu). In addition to displaying data in an organized manner, computational tools that use the underlying allele frequencies with user-provided data are implemented in FROG-kb. These tools are organized by the different published SNP/marker panels available. This web tool currently has implemented general functions possible for two types of SNP panels, individual identification and ancestry inference, and a prediction function specific to a phenotype informative panel for eye color. The current online version of FROG-kb already provides new and useful functionality. We expect FROG-kb to grow and expand in capabilities and welcome input from the forensic community in identifying datasets and functionalities that will be most helpful

Remodeling of ribosomal genes in somatic cells by Xenopus egg extract

Energy Technology Data Exchange (ETDEWEB)

Ostrup, Olga, E-mail: osvarcova@gmail.com [Institute of Basic Animal and Veterinary Sciences, Faculty of Life Sciences, University of Copenhagen, Frederiksberg C (Denmark); Stem Cell Epigenetics Laboratory, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo (Norway); Norwegian Center for Stem Cell Research, Oslo (Norway); Hyttel, Poul; Klaerke, Dan A. [Institute of Basic Animal and Veterinary Sciences, Faculty of Life Sciences, University of Copenhagen, Frederiksberg C (Denmark); Collas, Philippe, E-mail: philc@medisin.uio.no [Stem Cell Epigenetics Laboratory, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo (Norway); Norwegian Center for Stem Cell Research, Oslo (Norway)

2011-09-02

Highlights: {yields} Xenopus egg extract remodels nuclei and alter cell growth characteristics. {yields} Ribosomal genes are reprogrammed within 6 h after extract exposure. {yields} rDNA reprogramming involves promoter targeting of SNF2H remodeling complex. {yields} Xenopus egg extract does not initiate stress-related response in somatic cells. {yields} Aza-cytidine elicits a stress-induced response in reprogrammed cells. -- Abstract: Extracts from Xenopus eggs can reprogram gene expression in somatic nuclei, however little is known about the earliest processes associated with the switch in the transcriptional program. We show here that an early reprogramming event is the remodeling of ribosomal chromatin and gene expression. This occurs within hours of extract treatment and is distinct from a stress response. Egg extract elicits remodeling of the nuclear envelope, chromatin and nucleolus. Nucleolar remodeling involves a rapid and stable decrease in ribosomal gene transcription, and promoter targeting of the nucleolar remodeling complex component SNF2H without affecting occupancy of the transcription factor UBF and the stress silencers SUV39H1 and SIRT1. During this process, nucleolar localization of UBF and SIRT1 is not altered. On contrary, azacytidine pre-treatment has an adverse effect on rDNA remodeling induced by extract and elicits a stress-type nuclear response. Thus, an early event of Xenopus egg extract-mediated nuclear reprogramming is the remodeling of ribosomal genes involving nucleolar remodeling complex. Condition-specific and rapid silencing of ribosomal genes may serve as a sensitive marker for evaluation of various reprogramming methods.

Birds and frogs in mathematics and physics

Energy Technology Data Exchange (ETDEWEB)

Dyson, Freeman J [Institute for Advanced Study, Princeton, NJ (United States)

2010-11-15

Some scientists are birds, others are frogs. Birds fly high in the air and survey broad vistas of mathematics out to the far horizon. They delight in concepts that unify our thinking and bring together diverse problems from different parts of the landscape. Frogs live in the mud below and see only the flowers that grow nearby. They delight in the details of particular objects, and they solve problems one at a time. A brief history of mathematics and its applications in physics is presented in this article. (from the history of physics)

Birds and frogs in mathematics and physics

International Nuclear Information System (INIS)

Dyson, Freeman J

2010-01-01

Some scientists are birds, others are frogs. Birds fly high in the air and survey broad vistas of mathematics out to the far horizon. They delight in concepts that unify our thinking and bring together diverse problems from different parts of the landscape. Frogs live in the mud below and see only the flowers that grow nearby. They delight in the details of particular objects, and they solve problems one at a time. A brief history of mathematics and its applications in physics is presented in this article. (from the history of physics)

Properties of the chromatin assembled on DNA injected into Xenopus oocytes and eggs

International Nuclear Information System (INIS)

Gargiulo, G.; Wasserman, W.; Worcel, A.

1983-01-01

The onset of DNA synthesis occurs between 10 and 30 minutes after activation of the egg and thus the transition from nuclease-sensitive to nuclease-resistant supercoils may take place on the newly replicated DNA. To test this possibility, the nonradioactive circular 5-kb DNA carrying the Drosophila histone gene repeat and [α -32 P]dCTP were coinjected into fertilized eggs. Such protocol labels both the injected, replicated heterologous DNA and the replicated endogenous, maternal Xenopus DNA. The labeled, presumably replicated, supercoiled DNA is resistant to micrococcal nuclease as expected. The endogenous, high-molecular-weight Xenopus DNA is degraded to 180-bp nucleosomal DNA. Thus, the nuclease resistance is not a general property of chromatin during the cleavage stage of the Xenopus embryo but is a peculiar feature of the injected DNA. 42 references, 5 figures

Xenopus laevis Kif18A is a highly processive kinesin required for meiotic spindle integrity

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Martin M. Möckel

2017-04-01

Full Text Available The assembly and functionality of the mitotic spindle depends on the coordinated activities of microtubule-associated motor proteins of the dynein and kinesin superfamily. Our current understanding of the function of motor proteins is significantly shaped by studies using Xenopus laevis egg extract as its open structure allows complex experimental manipulations hardly feasible in other model systems. Yet, the Kinesin-8 orthologue of human Kif18A has not been described in Xenopus laevis so far. Here, we report the cloning and characterization of Xenopus laevis (Xl Kif18A. Xenopus Kif18A is expressed during oocyte maturation and its depletion from meiotic egg extract results in severe spindle defects. These defects can be rescued by wild-type Kif18A, but not Kif18A lacking motor activity or the C-terminus. Single-molecule microscopy assays revealed that Xl_Kif18A possesses high processivity, which depends on an additional C-terminal microtubule-binding site. Human tissue culture cells depleted of endogenous Kif18A display mitotic defects, which can be rescued by wild-type, but not tail-less Xl_Kif18A. Thus, Xl_Kif18A is the functional orthologue of human Kif18A whose activity is essential for the correct function of meiotic spindles in Xenopus oocytes.

Use of femur bone density to segregate wild from farmed Dybowski's frog (Rana dybowskii).

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Yang, Shu Hui; Huang, Xiao Ming; Xia, Rui; Xu, Yan Chun; Dahmer, Thomas D

2011-04-15

Wildlife has been utilized by humans throughout history and demand continues to grow today. Farming of wildlife can supplement the supply of wild-harvested wildlife products and, in theory, can reduce pressure on free-ranging populations. However, poached wildlife products frequently enter legal markets where they are fraudulently sold as farmed wildlife products. To effectively close this illegal trade in wild-captured wildlife, there is a need to discriminate wild products from farmed products. Because of the strong market demand for wild-captured frog meat and the resulting strong downward pressure on wild populations, we undertook research to develop a method to discriminate wild from farmed Dybowski's frog (Rana dybowskii) based on femur bone density. We measured femur bone density (D(f)) as the ratio of bone mass to bone volume. D(f) of wild frogs revealed a slightly increasing linear trend with increasing age (R(2)=0.214 in males and R(2)=0.111 in females, p=0.000). Wild males and wild females of age classes from 2 to ≥ 5 years had similar D(f) values. In contrast, 2-year-old farmed frogs showed significantly higher D(f) values (p=0.000) among males (mean D(f)=0.623 ± 0.011 g/ml, n=32) than females (mean D(f)=0.558 ± 0.011 g/ml, n=27). For both sexes, D(f) of wild frogs was significantly higher than that of farmed frogs (p=0.000). Among males, 87.5% (28 of 32 individuals) of farmed frogs were correctly identified as farmed frogs and 86.3% (69 of 80 individuals) of wild frogs were correctly identified as wild frogs. These results suggest that femur bone density is one reliable tool for discriminating between wild and farmed Dybowski's frog. This study also highlights a novel strategy with explicit forensic potential to discriminate wild from captive bred wildlife species. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Expression and hypophysiotropic actions of corticotropin-releasing factor in Xenopus laevis.

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Boorse, Graham C; Denver, Robert J

2004-07-01

Members of the corticotropin-releasing factor (CRF) family of peptides play pivotal roles in the regulation of neuroendocrine, autonomic, and behavioral responses to physical and emotional stress. In amphibian tadpoles, CRF-like peptides stimulate both thyroid and interrenal (adrenal) hormone secretion, and can thereby modulate the rate of metamorphosis. To better understand the regulation of expression and actions of CRF in amphibians we developed a homologous radioimmunoassay (RIA) for Xenopus laevis CRF (xCRF). We validated this RIA and tissue extraction procedure for the measurement of brain CRF content in tadpoles and juveniles. We show that the CRF-binding protein, which is highly expressed in X. laevis brain, is largely removed by acid extraction and does not interfere in the RIA. We analyzed CRF peptide content in five microdissected brain regions in prometamorphic tadpoles and juveniles. CRF was detected throughout the brain, consistent with its role as both a hypophysiotropin and a neurotransmitter/neuromodulator. CRF content was highest in the region of the preoptic area (POa) and increased in all brain regions after metamorphosis. Exposure to 4h of handling/shaking stress resulted in increased CRF peptide content in the POa in juvenile frogs. Injections of xCRF into prometamorphic tadpoles increased whole body corticosterone and thyroxine content, thus supporting findings in other anuran species that this peptide functions as both a corticotropin- and a thyrotropin (TSH)-releasing factor. Furthermore, treatment of cultured tadpole pituitaries with xCRF (100nM for 24h) resulted in increased medium content, but decreased pituitary content of TSHbeta-immunoreactivity. Our results support the view that CRF functions as a stress neuropeptide in X. laevis as in other vertebrates. Furthermore, we provide evidence for a dual hypophysiotropic action of CRF on the thyroid and interrenal axes in X. laevis as has been shown previously in other amphibian species.

Determination of age, longevity and age at reproduction of the frog ...

Indian Academy of Sciences (India)

Unknown

separately in plastic bags and placed in 5 different aquaria. Each frog was anaesthetized (using anaesthetic ether), the body mass ... bone of each frog, were measured using an ocular .... One of the problems generally associated with skeleto-.

Female preferences for aposematic signal components in a polymorphic poison frog

NARCIS (Netherlands)

Maan, Martine E.; Cummings, Molly E.

Aposematic signals may be subject to conflicting selective pressures from predators and conspecifics. We studied female preferences for different components of aposematic coloration in the polymorphic poison frog Oophaga pumilio across several phenotypically distinct populations. This frog shows

Antimicrobial peptides from the skins of North American frogs.

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Conlon, J Michael; Kolodziejek, Jolanta; Nowotny, Norbert

2009-08-01

North America is home to anuran species belonging to the families Bufonidae, Eleutherodactylidae, Hylidae, Leiopelmatidae, Ranidae, and Scaphiopodidae but antimicrobial peptides have been identified only in skin secretions and/or skin extracts of frogs belonging to the Leiopelmatidae ("tailed frogs") and Ranidae ("true frogs"). Eight structurally-related cationic alpha-helical peptides with broad-spectrum antibacterial activity, termed ascaphins, have been isolated from specimens of Ascaphus truei (Leiopelmatidae) occupying a coastal range. Characterization of orthologous antimicrobial peptides from Ascaphus specimens occupying an inland range supports the proposal that this population should be regarded as a separate species A. montanus. Ascaphin-8 shows potential for development into a therapeutically valuable anti-infective agent. Peptides belonging to the brevinin-1, esculentin-1, esculentin-2, palustrin-1, palustrin-2, ranacyclin, ranatuerin-1, ranatuerin-2, and temporin families have been isolated from North American ranids. It is proposed that "ranalexins" represent brevinin-1 peptides that have undergone a four amino acid residue internal deletion. Current taxonomic recommendations divide North American frogs from the family Ranidae into two genera: Lithobates and Rana. Cladistic analysis based upon the amino acid sequences of the brevinin-1 peptides provides strong support for this assignment.

Environmental and Host Effects on Skin Bacterial Community Composition in Panamanian Frogs

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Brandon J. Varela

2018-02-01

Full Text Available Research on the amphibian skin microbiota has focused on identifying bacterial taxa that deter a pathogenic chytrid fungus, and on describing patterns of microbiota variation. However, it remains unclear how environmental variation affects amphibian skin bacterial communities, and whether the overall functional diversity of the amphibian skin microbiota is associated to such variation. We sampled skin microbial communities from one dendrobatoid frog species across an environmental gradient along the Panama Canal, and from three dendrobatoid frog species before and after the onset of the wet season in one site. We found frog skin microbial alpha diversity to be highest in frogs from sites with low soil pH, but no clear effect of the onset of the wet season. However, we found frog skin microbial community structure to be affected by soil pH and the onset of the wet season, which also resulted in a decrease in between-sample variation. Across the sampled frog species, bacterial functional groups changed with the onset of the wet season, with certain bacterial functional groups entirely disappearing and others differing in their relative abundances. In particular, we found the proportion of Bd-inhibitory bacteria to correlate with mean soil pH, and to increase in two of the frog species with the onset of the wet season. Taken together, our results suggest that structure and predicted function of amphibian bacterial skin communities may be influenced by environmental variables such as pH and precipitation, site effects, and host effects.

Pathological Study of Blood Parasites in Rice Field Frogs, Hoplobatrachus rugulosus (Wiegmann, 1834

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Achariya Sailasuta

2011-01-01

Full Text Available One hundred and forty adult rice field frogs, Hoplobatrachus rugulosus (Wiegmann, 1834, were collected in Srakaew province, Thailand. For blood parasite examination, thin blood smears were made and routinely stained with Giemsa. The results showed that 70% of the frogs (98/140 were infected with 5 species of blood parasites, including a Trypanosoma rotatorium-like organism, Trypanosoma chattoni, Hepatozoon sp. a, Hepatozoon sp. b, and Lankesterella minima. Pathological examination of the liver, lung, spleen, and kidney of the frogs that were apparently infected with one of these blood parasites were collected and processed by routine histology and subsequently stained with haematoxylin and eosin. Histopathological findings associated with the Trypanosoma rotatorium-like organism and Trypanosoma chattoni-infected frogs showed no pathological lesions. Hepatozoon sp. a and Hepatozoon sp. b-infected frogs developed inflammatory lesions predominantly in the liver, demonstrating granuloma-like lesions with Hepatozoon sp. meronts at the centre. Tissue sections of Lankesterella minima-infected frogs also showed lesions. Liver and spleen showed inflammatory lesions with an accumulation of melanomacrophage centres (MMCs surrounding the meronts and merozoites. It is suggested that Hepatozoon sp. a, Hepatozoon sp. b, and Lankesterella minima-infections are capable of producing inflammatory lesions in the visceral organs of rice field frogs, and the severity of lesions is tentatively related to levels of parasitemia.

Pathological Study of Blood Parasites in Rice Field Frogs, Hoplobatrachus rugulosus (Wiegmann, 1834)

Science.gov (United States)

Sailasuta, Achariya; Satetasit, Jetjun; Chutmongkonkul, Malinee

2011-01-01

One hundred and forty adult rice field frogs, Hoplobatrachus rugulosus (Wiegmann, 1834), were collected in Srakaew province, Thailand. For blood parasite examination, thin blood smears were made and routinely stained with Giemsa. The results showed that 70% of the frogs (98/140) were infected with 5 species of blood parasites, including a Trypanosoma rotatorium-like organism, Trypanosoma chattoni, Hepatozoon sp. a, Hepatozoon sp. b, and Lankesterella minima. Pathological examination of the liver, lung, spleen, and kidney of the frogs that were apparently infected with one of these blood parasites were collected and processed by routine histology and subsequently stained with haematoxylin and eosin. Histopathological findings associated with the Trypanosoma rotatorium-like organism and Trypanosoma chattoni-infected frogs showed no pathological lesions. Hepatozoon sp. a and Hepatozoon sp. b-infected frogs developed inflammatory lesions predominantly in the liver, demonstrating granuloma-like lesions with Hepatozoon sp. meronts at the centre. Tissue sections of Lankesterella minima-infected frogs also showed lesions. Liver and spleen showed inflammatory lesions with an accumulation of melanomacrophage centres (MMCs) surrounding the meronts and merozoites. It is suggested that Hepatozoon sp. a, Hepatozoon sp. b, and Lankesterella minima-infections are capable of producing inflammatory lesions in the visceral organs of rice field frogs, and the severity of lesions is tentatively related to levels of parasitemia. PMID:21918731

Sophisticated Communication in the Brazilian Torrent Frog Hylodes japi.

Science.gov (United States)

de Sá, Fábio P; Zina, Juliana; Haddad, Célio F B

2016-01-01

Intraspecific communication in frogs plays an important role in the recognition of conspecifics in general and of potential rivals or mates in particular and therefore with relevant consequences for pre-zygotic reproductive isolation. We investigate intraspecific communication in Hylodes japi, an endemic Brazilian torrent frog with territorial males and an elaborate courtship behavior. We describe its repertoire of acoustic signals as well as one of the most complex repertoires of visual displays known in anurans, including five new visual displays. Previously unknown in frogs, we also describe a bimodal inter-sexual communication system where the female stimulates the male to emit a courtship call. As another novelty for frogs, we show that in addition to choosing which limb to signal with, males choose which of their two vocal sacs will be used for visual signaling. We explain how and why this is accomplished. Control of inflation also provides additional evidence that vocal sac movement and color must be important for visual communication, even while producing sound. Through the current knowledge on visual signaling in Neotropical torrent frogs (i.e. hylodids), we discuss and highlight the behavioral diversity in the family Hylodidae. Our findings indicate that communication in species of Hylodes is undoubtedly more sophisticated than we expected and that visual communication in anurans is more widespread than previously thought. This is especially true in tropical regions, most likely due to the higher number of species and phylogenetic groups and/or to ecological factors, such as higher microhabitat diversity.

Sophisticated Communication in the Brazilian Torrent Frog Hylodes japi.

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Fábio P de Sá

Full Text Available Intraspecific communication in frogs plays an important role in the recognition of conspecifics in general and of potential rivals or mates in particular and therefore with relevant consequences for pre-zygotic reproductive isolation. We investigate intraspecific communication in Hylodes japi, an endemic Brazilian torrent frog with territorial males and an elaborate courtship behavior. We describe its repertoire of acoustic signals as well as one of the most complex repertoires of visual displays known in anurans, including five new visual displays. Previously unknown in frogs, we also describe a bimodal inter-sexual communication system where the female stimulates the male to emit a courtship call. As another novelty for frogs, we show that in addition to choosing which limb to signal with, males choose which of their two vocal sacs will be used for visual signaling. We explain how and why this is accomplished. Control of inflation also provides additional evidence that vocal sac movement and color must be important for visual communication, even while producing sound. Through the current knowledge on visual signaling in Neotropical torrent frogs (i.e. hylodids, we discuss and highlight the behavioral diversity in the family Hylodidae. Our findings indicate that communication in species of Hylodes is undoubtedly more sophisticated than we expected and that visual communication in anurans is more widespread than previously thought. This is especially true in tropical regions, most likely due to the higher number of species and phylogenetic groups and/or to ecological factors, such as higher microhabitat diversity.

THE MOCHE BOTANICAL FROG (La rana botánica mochica

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Donna McClelland †

2011-06-01

Full Text Available Plants and animals with features which identify them as supernaturals characterize the art of the Precolumbian Moche culture of northern Peru. Among these animals is a frog with feline attributes and a consistent association with manioc tubers, stalks, and plants, the Botanical Frog. The Botanical Frog appears to have been patterned on Leptodactylus pentadactylus. It is shown copulating with felines. Fine line painted vessels and ones with low relief decoration show the Botanical Frog performing as part of a ritual involving other animals and cultivated crops, suggesting that the Botanical Frog was associated with agriculture. ESPAÑOL: El arte de la cultura mochica de la costa norte del Perú presenta plantas y animales mostrando rasgos sobrenaturales. Uno de los animales es una rana con elementos felinos y asociada con tubérculos, ramas y plantas de yuca. La Rana Botánica probablemente tiene su origen en Leptodactylus pentadactylus, una rana carnívora de la selva amazónica. La Rana Botánica copula con felinos y, en vasijas pintadas con líneas finas o con escenarios representados en bajorrelieve, toma parte en ceremonias involucrando a otros animales y cosechas domésticas. Parece ser que la Rana Botánica era un ser sobrenatural asociado con la agricultura.

Field guide to malformations of frogs and toads: with radiographic interpretations

Science.gov (United States)

Meteyer, Carol U.

2000-01-01

In 1995, students found numerous malformed frogs on a field trip to a Minnesota pond. Since that time, reports of malformed frogs have increased dramatically. Malformed frogs have now been reported in 44 states in 38 species of frogs, and 19 species of toads. Estimates as high as 60% of the newly metamorphosed frog populations have had malformations at some ponds (NARCAM, ’99). The wide geographic distribution of malformed frogs and the variety of malformations are a concern to resource managers, research scientists and public health officials. The potential for malformations to serve as a signal of ecosystem disruption, and the affect this potential disruption might have on other organisms that share those ecosystems, has not been resolved. Malformations represent an error that occurred early in development. The event that caused the developmental error is temporally distant from the malformation we see in the fully developed animal. Knowledge of normal developmental principles is necessary to design thoughtful investigations that will define the events involved in abnormal development in wild frog populations.Development begins at the time an egg is fertilized and progresses by chemical communication between cells and cell layers. This communication is programmed through gene expression. Malformations represent primary errors in development, errors in chemical communication or translation of genetic information. Deformations arise later in development and usually result from the influence of mechanical factors (such as amputation) that alter shape or anatomy of a structure that has developed normally. The occurrence and the type of malformations are influenced by the type of error or insult as well as the timing of the error (the developmental stage at which the error occurred). The appearance of the malformation can therefore provide clues that suggest when the error may have occurred. If the malformation is an incomplete organ, such as an incomplete limb, the

Using a Phototransduction System to Monitor the Isolated Frog Heart

Science.gov (United States)

Stephens, Philip J.

2015-01-01

A simple and inexpensive method of monitoring the movement of an isolated frog heart provides comparable results to those obtained with a force transducer. A commercially available photoresistor is integrated into a Wheatstone bridge circuit, and the output signal is interfaced directly with a recording device. An excised, beating frog heart is…

Highly efficient gene knockout by injection of TALEN mRNAs into oocytes and host transfer in Xenopus laevis

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Keisuke Nakajima

2015-01-01

Full Text Available Zinc-finger nucleases, transcription activator-like effector nucleases (TALENs and the CRISPR/Cas (clustered regularly interspaced short palindromic repeats/CRISPR-associated proteins system are potentially powerful tools for producing tailor-made knockout animals. However, their mutagenic activity is not high enough to induce mutations at all loci of a target gene throughout an entire tadpole. In this study, we present a highly efficient method for introducing gene modifications at almost all target sequences in randomly selected embryos. The gene modification activity of TALEN is enhanced by adopting the host-transfer technique. In our method, the efficiency is further improved by injecting TALEN mRNAs fused to the 3′UTR of the Xenopus DEADSouth gene into oocytes, which are then transferred into a host female frog, where they are ovulated and fertilized. The addition of the 3′UTR of the DEADSouth gene promotes mRNA translation in the oocytes and increases the expression of TALEN proteins to near-maximal levels three hours post fertilization (hpf. In contrast, TALEN mRNAs without this 3′UTR are translated infrequently in oocytes. Our data suggest that genomic DNA is more sensitive to TALEN proteins from fertilization to the midblastula (MBT stage. Our method works by increasing the levels of TALEN proteins during the pre-MBT stages.

The island rule in the Brazilian frog Phyllodytes luteolus (Anura: Hylidae: incipient gigantism?

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Marcio Mageski

2015-10-01

Full Text Available ABSTRACT The island rule suggests that, when mainland animals are isolated on islands, large animals tend to become smaller, while small animals tend to become larger. A small frog in eastern Brazil, Phyllodytes luteolus (Wied-Neuwied, 1824, is widely distributed in association with bromeliads. At the end of the last glaciation, parts of the mainland became islands due to rising sea levels, thereby isolating frog populations on these islands. If the island rule holds, we predicted that frogs on islands would tend to be larger than frogs on the mainland. We compared sizes (weight and length of 30 randomly selected male frogs from the mainland with 30 from an island in the state of Espírito Santo, Brazil. We also sampled population density on the island and mainland because concurrent with changing sizes, depending on the causal relationship, density may also change. As predicted, island frogs tended to be larger (both in snout-vent length and weight and were much more abundant. While not specifically addressed in this study, the absence of predators and interspecific competitors may explain both of these trends.

Sexual differences in prevalence of a new species of trypanosome infecting túngara frogs.

Science.gov (United States)

Bernal, Ximena E; Pinto, C Miguel

2016-04-01

Trypanosomes are a diverse group of protozoan parasites of vertebrates transmitted by a variety of hematophagous invertebrate vectors. Anuran trypanosomes and their vectors have received relatively little attention even though these parasites have been reported from frog and toad species worldwide. Blood samples collected from túngara frogs (Engystomops pustulosus), a Neotropical anuran species heavily preyed upon by eavesdropping frog-biting midges (Corethrella spp.), were examined for trypanosomes. Our results revealed sexual differences in trypanosome prevalence with female frogs being rarely infected (frog-biting midges that find their host using the mating calls produced by male frogs. Following previous anuran trypanosome studies, we examined 18S ribosomal RNA gene to characterize and establish the phylogenetic relationship of the trypanosome species found in túngara frogs. A new species of giant trypanosome, Trypanosoma tungarae n. sp., is described in this study. Overall the morphometric data revealed that the trypomastigotes of T. tungarae n. sp. are similar to other giant trypanosomes such as Trypanosoma rotatorium and Trypanosoma ranarum. Despite its slender and long cell shape, however, 18S rRNA gene sequences revealed that T. tungarae n. sp. is sister to the rounded-bodied giant trypanosome, Trypanosoma chattoni. Therefore, morphological convergence explains similar morphology among members of two non-closely related groups of trypanosomes infecting frogs. The results from this study underscore the value of coupling morphological identification with molecular characterization of anuran trypanosomes.

Assessment of frog meat utilisation in Ibadan, Oyo state, Nigeria ...

African Journals Online (AJOL)

Frogs are among the most threatened species of wildlife in IUCN red list. Its utilisation in Ibadan, a major depot in western Nigeria was therefore conducted with the aim of assessing the forms and trend of use; and amongst others, reasons for frog meat consumption. Data for the study were collected through questionnaire, ...

The redesigned Forensic Research/Reference on Genetics-knowledge base, FROG-kb.

Science.gov (United States)

Kidd, Kenneth K; Soundararajan, Usha; Rajeevan, Haseena; Pakstis, Andrew J; Moore, Katherine N; Ropero-Miller, Jeri D

2018-03-01

The Forensic Resource/Reference on Genetics-knowledge base (FROG-kb) web site was introduced in 2011 and in the five years since the previous publication ongoing research into how the database can better serve forensics has resulted in extensive redesign of the database interface and functionality. Originally designed as a prototype to support forensic use of single nucleotide polymorphisms (SNPs), FROG-kb provides a freely accessible web interface that facilitates forensic practice and can be useful for teaching and research. Based on knowledge gained through its use, the web interface has been redesigned for easier navigation through the multiple components. The site also has functional enhancements, extensive new documentation, and new reference panels of SNPs with new curated data. FROG-kb focuses on single nucleotide polymorphisms (SNPs) and provides reference population data for several published panels of individual identification SNPs (IISNPs) and several published panels of ancestry inference SNPs (AISNPs). For each of the various marker panels with reference population data, FROG-kb calculates random match probabilities (RMP) and relative likelihoods of ancestry for a user-entered genotype profile (either completely or partially specified). Example genotype profiles are available and the User's Manual presents interpretation guidelines for the calculations. The extensive documentation along with ongoing updates makes FROG-kb a comprehensive tool in facilitating use of SNPs in forensic practice and education. An overview of the new FROG-kb with examples and material explaining the results of its use are presented here. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Propulsive force calculations in swimming frogs I. A momentum-impulse approach

NARCIS (Netherlands)

Nauwelaerts, S; Stamhuis, EJ; Aerts, P

Frogs are animals that are capable of locomotion in two physically different media, aquatic and terrestrial. A comparison of the kinematics of swimming frogs in a previous study revealed a difference in propulsive impulse between jumping and swimming. To explore this difference further, we

Guinea Worm in a Frog

Centers for Disease Control (CDC) Podcasts

2017-03-09

Dr. Mark Eberhard, a retired parasitologist and CDC guest researcher, discusses Guinea worm infection in a wild-caught frog.  Created: 3/9/2017 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 3/9/2017.

Frankixalus, a New Rhacophorid Genus of Tree Hole Breeding Frogs with Oophagous Tadpoles.

Directory of Open Access Journals (Sweden)

S D Biju

Full Text Available Despite renewed interest in the biogeography and evolutionary history of Old World tree frogs (Rhacophoridae, this family still includes enigmatic frogs with ambiguous phylogenetic placement. During fieldwork in four northeastern states of India, we discovered several populations of tree hole breeding frogs with oophagous tadpoles. We used molecular data, consisting of two nuclear and three mitochondrial gene fragments for all known rhacophorid genera, to investigate the phylogenetic position of these new frogs. Our analyses identify a previously overlooked, yet distinct evolutionary lineage of frogs that warrants recognition as a new genus and is here described as Frankixalus gen. nov. This genus, which contains the enigmatic 'Polypedates' jerdonii described by Günther in 1876, forms the sister group of a clade containing Kurixalus, Pseudophilautus, Raorchestes, Mercurana and Beddomixalus. The distinctiveness of this evolutionary lineage is also corroborated by the external morphology of adults and tadpoles, adult osteology, breeding ecology, and life history features.

Apoptosis regulates notochord development in Xenopus

OpenAIRE

Malikova, Marina; Van Stry, Melanie; Symes, Karen

2007-01-01

The notochord is the defining characteristic of the chordate embryo, and plays critical roles as a signaling center and as the primitive skeleton. In this study we show that early notochord development in Xenopus embryos is regulated by apoptosis. We find apoptotic cells in the notochord beginning at the neural groove stage and increasing in number as the embryo develops. These dying cells are distributed in an anterior to posterior pattern that is correlated with notochord extension through ...

Sequestered Alkaloid Defenses in the Dendrobatid Poison Frog Oophaga pumilio Provide Variable Protection from Microbial Pathogens.

Science.gov (United States)

Hovey, Kyle J; Seiter, Emily M; Johnson, Erin E; Saporito, Ralph A

2018-03-01

Most amphibians produce their own defensive chemicals; however, poison frogs sequester their alkaloid-based defenses from dietary arthropods. Alkaloids function as a defense against predators, and certain types appear to inhibit microbial growth. Alkaloid defenses vary considerably among populations of poison frogs, reflecting geographic differences in availability of dietary arthropods. Consequently, environmentally driven differences in frog defenses may have significant implications regarding their protection against pathogens. While natural alkaloid mixtures in dendrobatid poison frogs have recently been shown to inhibit growth of non-pathogenic microbes, no studies have examined the effectiveness of alkaloids against microbes that infect these frogs. Herein, we examined how alkaloid defenses in the dendrobatid poison frog, Oophaga pumilio, affect growth of the known anuran pathogens Aeromonas hydrophila and Klebsiella pneumoniae. Frogs were collected from five locations throughout Costa Rica that are known to vary in their alkaloid profiles. Alkaloids were isolated from individual skins, and extracts were assayed against both pathogens. Microbe subcultures were inoculated with extracted alkaloids to create dose-response curves. Subsequent spectrophotometry and cell counting assays were used to assess growth inhibition. GC-MS was used to characterize and quantify alkaloids in frog extracts, and our results suggest that variation in alkaloid defenses lead to differences in inhibition of these pathogens. The present study provides the first evidence that alkaloid variation in a dendrobatid poison frog is associated with differences in inhibition of anuran pathogens, and offers further support that alkaloid defenses in poison frogs confer protection against both pathogens and predators.

BIOMETRIC STUDY TO RANA RIDIBUNDA FROG SPECIES NEARNESS TO TIMISOARA LOCALITY

Directory of Open Access Journals (Sweden)

M. BURA

2007-10-01

Full Text Available Speciality literature provides little informations regarding Rana ridibunda frogbiometry. For supply this gap we studied the size and weight of 54 frogs sampled fromnearby Timişoara area ponds.The mean body lenght was 8,08 ± 0,54 cm for the females and respectively 6,17 ± 0,45cm for the males. Before evisceration on a par females weighted 62,28 ± 12,87 g andthe males 22,46 ± 5,3 g whereas after this action the carcase weighted 43,89 ± 8,91 gin the case of females and respectively 18,45 ± 4,42 g in the case of male lake frog. Themean leg lenght measured 12,59 ± 0,68 cm for female frogs and 9,78 ± 0,66 cm in thecase of male frogs. The hind stylopodium was estimated on a par as 13,23 ± 2,57 g forfemales and 5,33 ± 1,26 g for the males.

Sexual differences in prevalence of a new species of trypanosome infecting túngara frogs

Directory of Open Access Journals (Sweden)

Ximena E. Bernal

2016-04-01

Full Text Available Trypanosomes are a diverse group of protozoan parasites of vertebrates transmitted by a variety of hematophagous invertebrate vectors. Anuran trypanosomes and their vectors have received relatively little attention even though these parasites have been reported from frog and toad species worldwide. Blood samples collected from túngara frogs (Engystomops pustulosus, a Neotropical anuran species heavily preyed upon by eavesdropping frog-biting midges (Corethrella spp., were examined for trypanosomes. Our results revealed sexual differences in trypanosome prevalence with female frogs being rarely infected (<1%. This finding suggests this protozoan parasite may be transmitted by frog-biting midges that find their host using the mating calls produced by male frogs. Following previous anuran trypanosome studies, we examined 18S ribosomal RNA gene to characterize and establish the phylogenetic relationship of the trypanosome species found in túngara frogs. A new species of giant trypanosome, Trypanosoma tungarae n. sp., is described in this study. Overall the morphometric data revealed that the trypomastigotes of T. tungarae n. sp. are similar to other giant trypanosomes such as Trypanosoma rotatorium and Trypanosoma ranarum. Despite its slender and long cell shape, however, 18S rRNA gene sequences revealed that T. tungarae n. sp. is sister to the rounded-bodied giant trypanosome, Trypanosoma chattoni. Therefore, morphological convergence explains similar morphology among members of two non-closely related groups of trypanosomes infecting frogs. The results from this study underscore the value of coupling morphological identification with molecular characterization of anuran trypanosomes.

Hematophagous insects as vectors for frog trypanosomes.

Science.gov (United States)

Ramos, B; Urdaneta-Morales, S

1977-12-01

Experimental infections of three hematophagous arthropods (Rhodnius prolixus, Aedes aegypti, and Culex pipiens) with a trypanosome of the Trypanosoma rotatorium complex found in the frogs Hyla crepitans and Leptodactylus insularum revealed that A. aegypti is a good host for the flagellate; the course of development in the intestinal tract of the mosquito is described from 15 minutes to 168 hours. C. pipiens showed only low intestinal infections and R. prolixus did not permit development of the parasite. It is postulated that, in addition to the transmission of T. rotatorium by leeches, batrachophilic mosquitoes may transmit the parasite to frogs of more terrestrial habits by being ingested by these anurans.

Impact of Dams on Riparian Frog Communities in the Southern Western Ghats, India

Directory of Open Access Journals (Sweden)

Rohit Naniwadekar

2014-08-01

Full Text Available The Western Ghats is a global biodiversity hotspot and home to diverse and unique assemblages of amphibians. Several rivers originate from these mountains and hydropower is being tapped from them. The impacts of hydrological regulation of riparian ecosystems to wildlife and its habitat are poorly documented, and in particular the fate of frog populations is unknown. We examined the effects of dams on riparian frog communities in the Thamirabarani catchment in southern Western Ghats. We used nocturnal visual encounter surveys constrained for time, to document the species richness of frogs below and above the dam, and also at control sites in the same catchment. While we did not find differences in species richness below and above the dams, the frog community composition was significantly altered as a likely consequence of altered flow regime. The frog species compositions in control sites were similar to above-dam sites. Below-dam sites had a distinctly different species composition. Select endemic frog species appeared to be adversely impacted due to the dams. Below-dam sites had a greater proportion of generalist and widely distributed species. Dams in the Western Ghats appeared to adversely impact population of endemic species, particularly those belonging to the genus Nyctibatrachus that shows specialization for intact streams.

Aberrant femoral torsion presenting with frog-leg squatting mimicking gluteal muscle contracture.

Science.gov (United States)

Chiang, Chia-Ling; Tsai, Meng-Yuan; Chang, Wei-Ning; Chen, Clement Kuen-Huang

2012-04-01

Patients with frog-leg squatting have restricted internal rotation and adduction of the affected hips during sitting or squatting. In the surgical literature, the cause generally has been presumed to arise from and be pathognomonic for gluteal muscle contracture. However, we have encountered patients with frog-leg squatting but without gluteal muscle contracture. We therefore raised the following questions: What are the imaging features of patients with frog-leg squatting? Do conditions other than gluteal muscle contracture manifest frog-leg squatting? We retrospectively reviewed the MR images of 67 patients presenting with frog-leg squatting from April 1998 to July 2010. There were four females and 63 males; their mean age was 22.2 years (range, 4-50 years). During MRI readout, we observed aberrant axes of some femoral necks and obtained additional CT to measure femoral torsion angles in 59 of the 67 patients. MR images of 27 (40%) patients had signs of gluteal muscle contracture. Twenty-two (33%) patients (40 femora) had aberrant femoral torsion, including diminished anteversion (range, 6°-0°; average, 3.9°) in 11 femora of eight patients and femoral retroversion (range, muscle contracture or aberrant femoral torsion. The observation of aberrant femoral torsion was not anticipated before imaging studies. In addition to gluteal muscle contracture, aberrant femoral torsion can be a cause of frog-leg squatting. Level II, diagnostic study. See the guidelines for Authors for a complete description of levels of evidence.

A transgenic Xenopus laevis reporter model to study lymphangiogenesis

Directory of Open Access Journals (Sweden)

Annelii Ny

2013-07-01

The importance of the blood- and lymph vessels in the transport of essential fluids, gases, macromolecules and cells in vertebrates warrants optimal insight into the regulatory mechanisms underlying their development. Mouse and zebrafish models of lymphatic development are instrumental for gene discovery and gene characterization but are challenging for certain aspects, e.g. no direct accessibility of embryonic stages, or non-straightforward visualization of early lymphatic sprouting, respectively. We previously demonstrated that the Xenopus tadpole is a valuable model to study the processes of lymphatic development. However, a fluorescent Xenopus reporter directly visualizing the lymph vessels was lacking. Here, we created transgenic Tg(Flk1:eGFP Xenopus laevis reporter lines expressing green fluorescent protein (GFP in blood- and lymph vessels driven by the Flk1 (VEGFR-2 promoter. We also established a high-resolution fluorescent dye labeling technique selectively and persistently visualizing lymphatic endothelial cells, even in conditions of impaired lymph vessel formation or drainage function upon silencing of lymphangiogenic factors. Next, we applied the model to dynamically document blood and lymphatic sprouting and patterning of the initially avascular tadpole fin. Furthermore, quantifiable models of spontaneous or induced lymphatic sprouting into the tadpole fin were developed for dynamic analysis of loss-of-function and gain-of-function phenotypes using pharmacologic or genetic manipulation. Together with angiography and lymphangiography to assess functionality, Tg(Flk1:eGFP reporter tadpoles readily allowed detailed lymphatic phenotyping of live tadpoles by fluorescence microscopy. The Tg(Flk1:eGFP tadpoles represent a versatile model for functional lymph/angiogenomics and drug screening.

First report of Hepatozoon sp. in the Oregon spotted frog, Rana pretiosa.

Science.gov (United States)

Stenberg, Patricia L; Bowerman, William J

2010-07-01

From 2005 through 2008, we screened 650 Oregon spotted frogs (Rana pretiosa) from three populations in central Oregon, USA, for hemoparasites. A Hepatozoon sp., not previously reported in R. pretiosa, was found in one population of frogs, mostly as intracellular gamonts at a prevalence of 10.5% with parasitemias ranging from 0.02% to greater than 42% of erythrocytes within individual frogs. Intra-and extracellular merozoites were present, but rare. A potential vector, the mosquito Culex boharti, was common throughout the habitat of the population carrying Hepatozoon sp.

Bacterial flora on Cascades frogs in the Klamath Mountains of California

Science.gov (United States)

Karen Pope

2013-01-01

Amphibians are experiencing global declines due in part to the infectious disease chytridiomycosis. Some symbiotic bacteria residents on frog skin have been shown to inhibit the growth of Batrachochytrium dendrobatitis (Bd) but few studies have attempted to fully describe the resident bacterial flora of frog skin. We cultured and sequenced 130...

Salmonella Infection and Water Frogs

Centers for Disease Control (CDC) Podcasts

2010-01-12

This podcast, featuring lead investigator Shauna Mettee, discusses the first known outbreak of Salmonella in people due to contact with water frogs.  Created: 1/12/2010 by National Center for Zoonotic, Vector-Borne, and Enteric Diseases (NCZVED).   Date Released: 1/12/2010.

The cellular distribution of histone H5 in embryonic and adult tissues of Xenopus laevis and chicken

NARCIS (Netherlands)

Moorman, A. F.; de Boer, P. A.; Lamers, W. H.; Charles, R.

1986-01-01

The cellular distribution of histone H5 in embryonic and adult tissues of Xenopus laevis and chicken has been established with monoclonal antibodies to histone H5. Both in Xenopus and in chicken, the protein has presumably a more widespread cellular distribution than hitherto expected but is absent

Natural disturbance reduces disease risk in endangered rainforest frog populations.

Science.gov (United States)

Roznik, Elizabeth A; Sapsford, Sarah J; Pike, David A; Schwarzkopf, Lin; Alford, Ross A

2015-08-21

Natural disturbances can drive disease dynamics in animal populations by altering the microclimates experienced by hosts and their pathogens. Many pathogens are highly sensitive to temperature and moisture, and therefore small changes in habitat structure can alter the microclimate in ways that increase or decrease infection prevalence and intensity in host populations. Here we show that a reduction of rainforest canopy cover caused by a severe tropical cyclone decreased the risk of endangered rainforest frogs (Litoria rheocola) becoming infected by a fungal pathogen (Batrachochytrium dendrobatidis). Reductions in canopy cover increased the temperatures and rates of evaporative water loss in frog microhabitats, which reduced B. dendrobatidis infection risk in frogs by an average of 11-28% in cyclone-damaged areas, relative to unaffected areas. Natural disturbances to the rainforest canopy can therefore provide an immediate benefit to frogs by altering the microclimate in ways that reduce infection risk. This could increase host survival and reduce the probability of epidemic disease outbreaks. For amphibian populations under immediate threat from this pathogen, targeted manipulation of canopy cover could increase the availability of warmer, drier microclimates and therefore tip the balance from host extinction to coexistence.

Eleutherodactylus frog introductions to Hawaii

Science.gov (United States)

Kraus, Fred; Campbell, Earl W.; Allison, Allen; Pratt, Thane K.

1999-01-01

As an oceanic archipelago isolated from continental source areas, Hawaii lacks native terrestrial reptiles and amphibians, Polynesians apparently introduced seven gecko and skink species after discovering the islands approximately 1500 years ago, and another 15 reptiles and five frogs have been introduced in the last century and a half (McKeown 1996). The Polynesian introductions are probably inadvertent because the species involved are known stowaway dispersers (Gibbons 1985; Dye and Steadman 1990), In contrast, most of the herpetological introductions since European contact with Hawaii have been intentional. Several frog species were released for biocontrol of insects (e.g., Dendrobates auratus, Bufo marinus, Rana rugosa, Bryan 1932; Oliver and Shaw 1953), and most of the remaining species are released or escaped pets (e.g., Phelsuma spp., Chamaeleo jacksonii, Iguana iguana, McKeown 1996), Government-approved releases have not occurred for many years, but the rate of establishment of new species has increased in the past few decades because of the importation and subsequent release of pets.

Dry-season retreat and dietary shift of the dart-poison frog Dendrobates tinctorius (Anura: Dendrobatidae

Directory of Open Access Journals (Sweden)

Marga Born

2010-07-01

Full Text Available Seasonal rainfall affects tropical forest dynamics and behaviorof species that are part of these ecosystems. The positive correlation between amphibian activity patterns and rainfall has been demonstrated repeatedly. Members of Dendrobatidae, a clade of Neotropical dart-poison frogs, are well known for their habitat use and behavior during the rainy season, but their behavior during the dry season has received little attention. We studied habitat use and diet of the dendrobatid frog Dendrobates tinctorius in French Guiana during the rainy and dry seasons. Unlike many other dendrobatid frogs, D. tinctorius does not maintain territories for the entire rainy season. Both sexes colonize recently formed canopy-gaps and stay in these forest patches for only a few weeks. The frogs inthese patches consume a great diversity of prey, consisting of ants, beetles, wasps, insect larvae, and mites. During the dry season, frogs move to retreat sites in mature forest, such as palm bracts and tree holes. The frogs are less active and consume fewer prey items in the dry season, and they consume fewer wasps and insect larvae, but more termites. Ants are the most common prey items during both the wet and dry seasons. We discuss the effects of shifts in seasonal habitat use on the territorial behavior of dendrobatid frogs.

Archaeobatrachian paraphyly and pangaean diversification of crown-group frogs.

Science.gov (United States)

Roelants, Kim; Bossuyt, Franky

2005-02-01

Current models for the early diversification of living frogs inferred from morphological, ontogenetic, or DNA sequence data invoke very different scenarios of character evolution and biogeography. To explore central controversies on the phylogeny of Anura, we analyzed nearly 4000 base pairs of mitochondrial and nuclear DNA for the major frog lineages. Likelihood-based analyses of this data set are congruent with morphological evidence in supporting a paraphyletic arrangement of archaeobatrachian frogs, with an (Ascaphus + Leiopelma) clade as the sister-group of all other living anurans. The stability of this outcome is reinforced by screening for phylogenetic bias resulting from site-specific rate variation, homoplasy, or the obligatory use of distantly related outgroups. Twenty-one alternative branching and rooting hypotheses were evaluated using a nonparametric multicomparison test and parametric bootstrapping. Relaxed molecular clock estimates situate the emergence of crown-group anurans in the Triassic, approximately 55 million years prior to their first appearance in the fossil record. The existence of at least four extant frog lineages on the supercontinent Pangaea before its breakup gains support from the estimation that three early splits between Laurasia- and Gondwana-associated families coincide with the initial rifting of these landmasses. This observation outlines the potential significance of this breakup event in the formation of separate Mesozoic faunal assemblages in both hemispheres.

Semaphoring in an earless frog: the origin of a novel visual signal.

Science.gov (United States)

Lindquist, E D; Hetherington, T E

1998-10-01

Social communication in anuran amphibians (frogs and toads) is mediated predominantly by acoustic signals. Unlike most anurans, the Panamanian golden frog, Atelopus zeteki, lacks a standard tympanic middle ear and appears to have augmented its communicatory repertoire to include rotational limb motions as visual signals, referred to here as semaphores. The communicatory nature of semaphoring was inferred from experimental manipulations using mirrored self-image presentations and nonresident introductions. Male frogs semaphored significantly more when presented with a mirrored self-image than with a nonreflective control. Novel encounters between resident males and nonresident frogs demonstrated that semaphores were used directionally and were displayed toward target individuals. Females semaphored frequently and this observation represents a rare case of signaling by females in a typically male-biased communicatory regime. Semaphore actions were clearly linked to a locomotory gait pattern and appear to have originated as an elaboration of a standard stepping motion.

Interactive effects of ultraviolet-B radiation and pesticide exposure on DNA photo-adduct accumulation and expression of DNA damage and repair genes in Xenopus laevis embryos

International Nuclear Information System (INIS)

Yu, Shuangying; Tang, Song; Mayer, Gregory D.; Cobb, George P.; Maul, Jonathan D.

2015-01-01

Highlights: • Interactive effects of UVB radiation-pesticide co-exposures were examined in frogs. • Responses included induction of DNA photo-adducts and DNA damage and repair genes. • Elevated DNA adduct levels occurred for co-exposures compared to UVB alone. • One mechanism is that pesticides may alter nuclear excision repair gene expression. - Abstract: Pesticide use and ultraviolet-B (UVB) radiation have both been suggested to adversely affect amphibians; however, little is known about their interactive effects. One potential adverse interaction could involve pesticide-induced dysregulation of DNA repair pathways, resulting in greater numbers of DNA photo-adducts from UVB exposure. In the present study, we investigated the interactive effects of UVB radiation and two common pesticides (endosulfan and α-cypermethrin) on induction of DNA photo-adducts and expression of DNA damage and repair related genes in African clawed frog (Xenopus laevis) embryos. We examined 13 genes that are, collectively, involved in stress defense, cell cycle arrest, nucleotide excision repair (NER), base excision repair, mismatch repair, DNA repair regulation, and apoptosis. We exposed X. laevis embryos to 0, 25, and 50 μg/L endosulfan or 0, 2.5, and 5.0 μg/L α-cypermethrin for 96 h, with environmentally relevant exposures of UVB radiation during the last 7 h of the 96 h exposure. We measured the amount of cyclobutane pyrimidine dimers (CPDs) and mRNA abundance of the 13 genes among treatments including control, pesticide only, UVB only, and UVB and pesticide co-exposures. Each of the co-exposure scenarios resulted in elevated CPD levels compared to UVB exposure alone, suggesting an inhibitory effect of endosulfan and α-cypermethrin on CPD repair. This is attributed to results indicating that α-cypermethrin and endosulfan reduced mRNA abundance of XPA and HR23B, respectively, to levels that may affect the initial recognition of DNA lesions. In contrast, both pesticides

Biodiversity of frog haemoparasites from sub-tropical northern KwaZulu-Natal, South Africa.

Science.gov (United States)

Netherlands, Edward C; Cook, Courtney A; Kruger, Donnavan J D; du Preez, Louis H; Smit, Nico J

2015-04-01

Since South Africa boasts a high biodiversity of frog species, a multispecies haemoparasite survey was conducted by screening the blood from 29 species and 436 individual frogs. Frogs were collected at three localities in sub-tropical KwaZulu-Natal, a hotspot for frog diversity. Twenty per cent of the frogs were infected with at least one of five groups of parasites recorded. Intraerythrocytic parasites comprising Hepatozoon, Dactylosoma, and viral or bacterial organisms, as well as extracellular parasites including trypanosomes and microfilarid nematodes were found. A significant difference (P frog species. None of those species described as purely terrestrial and aquatic were infected. Hepatozoon and Trypanosoma species accounted for most of the infections, the former demonstrating significant differences in intensity of infection across species, families and habitat types (P = 0.028; P = 0.006; P = 0.007 respectively). Per locality, the first, the formally protected Ndumo Game Reserve, had the highest biodiversity of haemoparasite infections, with all five groups of parasites recorded. The other two sites, that is the area bordering the reserve and the Kwa Nyamazane Conservancy, had a lower diversity with no parasite infections recorded and only Hepatozoon species recorded respectively. Such findings could be ascribed to the anthropogenic impact on the latter two sites, the first by the rural village activities, and the second by the bordering commercial sugar cane agriculture. Future studies should include both morphological and molecular descriptions of the above parasites, as well as the identification of potential vectors, possibly clarifying the effects human activities may have on frog haemoparasite life cycles and as such their biodiversity.

Prostaglandin E2 release from dermis regulates sodium permeability of frog skin epithelium

DEFF Research Database (Denmark)

Rytved, Klaus A.; Brodin, Birger; Nielsen, Robert

1995-01-01

Arachidonic acid, cAMP, epithelium, frog skin, intracellular calcium, prostaglandin E*U2, sodium transport, tight epithelium.......Arachidonic acid, cAMP, epithelium, frog skin, intracellular calcium, prostaglandin E*U2, sodium transport, tight epithelium....

Sexual differences in prevalence of a new species of trypanosome infecting t?ngara frogs

OpenAIRE

Bernal, Ximena E.; Pinto, C. Miguel

2016-01-01

Trypanosomes are a diverse group of protozoan parasites of vertebrates transmitted by a variety of hematophagous invertebrate vectors. Anuran trypanosomes and their vectors have received relatively little attention even though these parasites have been reported from frog and toad species worldwide. Blood samples collected from túngara frogs (Engystomops pustulosus), a Neotropical anuran species heavily preyed upon by eavesdropping frog-biting midges (Corethrella spp.), were examined for trypa...

Functional evolution of the vitamin D and pregnane X receptors

Directory of Open Access Journals (Sweden)

Ou Junhai

2007-11-01

Full Text Available Abstract Background The vitamin D receptor (VDR and pregnane X receptor (PXR are nuclear hormone receptors of the NR1I subfamily that show contrasting patterns of cross-species variation. VDR and PXR are thought to have arisen from duplication of an ancestral gene, evident now as a single gene in the genome of the chordate invertebrate Ciona intestinalis (sea squirt. VDR genes have been detected in a wide range of vertebrates including jawless fish. To date, PXR genes have not been found in cartilaginous fish. In this study, the ligand selectivities of VDRs were compared in detail across a range of vertebrate species and compared with those of the Ciona VDR/PXR. In addition, several assays were used to search for evidence of PXR-mediated hepatic effects in three model non-mammalian species: sea lamprey (Petromyzon marinus, zebrafish (Danio rerio, and African clawed frog (Xenopus laevis. Results Human, mouse, frog, zebrafish, and lamprey VDRs were found to have similar ligand selectivities for vitamin D derivatives. In contrast, using cultured primary hepatocytes, only zebrafish showed evidence of PXR-mediated induction of enzyme expression, with increases in testosterone 6β-hydroxylation activity (a measure of cytochrome P450 3A activity in other species and flurbiprofen 4-hydroxylation activity (measure of cytochrome P450 2C activity following exposure to known PXR activators. A separate assay in vivo using zebrafish demonstrated increased hepatic transcription of another PXR target, multidrug resistance gene (ABCB5, following injection of the major zebrafish bile salt, 5α-cyprinol 27-sulfate. The PXR target function, testosterone hydroxylation, was detected in frog and sea lamprey primary hepatocytes, but was not inducible in these two species by a wide range of PXR activators in other animals. Analysis of the sea lamprey draft genome also did not show evidence of a PXR gene. Conclusion Our results show tight conservation of ligand

Detecting fish parvalbumin with commercial mouse monoclonal anti-frog parvalbumin IgG.

Science.gov (United States)

Chen, Lingyun; Hefle, Sue L; Taylor, Steve L; Swoboda, Ines; Goodman, Richard E

2006-07-26

Parvalbumin is a calcium-binding muscle protein that is highly conserved across fish species and amphibians. It is the major cross-reactive allergen associated with both fish and frog allergy. We used two-dimensional electrophoretic and immunoblotting techniques to investigate the utility of a commercial monoclonal anti-frog parvalbumin IgG for detecting parvalbumin present in some commonly consumed fish species. The 2D electrophoresis and immunoblots revealed species-specific differences in proteins that appear to represent various numbers of isoforms of parvalbumin in carp (5), catfish (3), cod (1) and tilapia (2). No parvalbumin was detected in yellowfin tuna. Based on minor differences in relative intensities of protein staining and immunodetection, parvalbumin isoforms may have slight differences in the epitope region recognized by the anti-frog parvalbumin antibody. These results suggest that the frog anti-parvalbumin antibody can be used as a valuable tool to detect parvalbumins from the fish tested in this study, except yellowfin tuna.

Effects of the Chytrid fungus on the Tarahumara frog (Rana tarahumarae) in Arizona and Sonora, Mexico

Science.gov (United States)

Stephen F. Hale; Philip C. Rosen; James L. Jarchow; Gregory A. Bradley

2005-01-01

We conducted histological analyses on museum specimens collected 1975-1999 from 10 sites in Arizona and Sonora to test for the pathogenic chytrid fungus (Batrachochytrium dendrobatidis) in ranid frogs, focusing on the Tarahumara frog (Rana tarahumarae). During 1981-2000, frogs displaying disease signs were found in the field, and...

Zebrafish transgenic constructs label specific neurons in Xenopus laevis spinal cord and identify frog V0v spinal neurons.

Science.gov (United States)

Juárez-Morales, José L; Martinez-De Luna, Reyna I; Zuber, Michael E; Roberts, Alan; Lewis, Katharine E

2017-09-01

A correctly functioning spinal cord is crucial for locomotion and communication between body and brain but there are fundamental gaps in our knowledge of how spinal neuronal circuitry is established and functions. To understand the genetic program that regulates specification and functions of this circuitry, we need to connect neuronal molecular phenotypes with physiological analyses. Studies using Xenopus laevis tadpoles have increased our understanding of spinal cord neuronal physiology and function, particularly in locomotor circuitry. However, the X. laevis tetraploid genome and long generation time make it difficult to investigate how neurons are specified. The opacity of X. laevis embryos also makes it hard to connect functional classes of neurons and the genes that they express. We demonstrate here that Tol2 transgenic constructs using zebrafish enhancers that drive expression in specific zebrafish spinal neurons label equivalent neurons in X. laevis and that the incorporation of a Gal4:UAS amplification cassette enables cells to be observed in live X. laevis tadpoles. This technique should enable the molecular phenotypes, morphologies and physiologies of distinct X. laevis spinal neurons to be examined together in vivo. We have used an islet1 enhancer to label Rohon-Beard sensory neurons and evx enhancers to identify V0v neurons, for the first time, in X. laevis spinal cord. Our work demonstrates the homology of spinal cord circuitry in zebrafish and X. laevis, suggesting that future work could combine their relative strengths to elucidate a more complete picture of how vertebrate spinal cord neurons are specified, and function to generate behavior. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 1007-1020, 2017. © 2017 Wiley Periodicals, Inc.

Dietary alkaloid sequestration in a poison frog: an experimental test of alkaloid uptake in Melanophryniscus stelzneri (Bufonidae).

Science.gov (United States)

Hantak, Maggie M; Grant, Taran; Reinsch, Sherri; McGinnity, Dale; Loring, Marjorie; Toyooka, Naoki; Saporito, Ralph A

2013-12-01

Several lineages of brightly colored anurans independently evolved the ability to secrete alkaloid-containing defensive chemicals from granular glands in the skin. These species, collectively referred to as 'poison frogs,' form a polyphyletic assemblage that includes some species of Dendrobatidae, Mantellidae, Myobatrachidae, Bufonidae, and Eleutherodactylidae. The ability to sequester alkaloids from dietary arthropods has been demonstrated experimentally in most poison frog lineages but not in bufonid or eleutherodactylid poison frogs. As with other poison frogs, species of the genus Melanophryniscus (Bufonidae) consume large numbers of mites and ants, suggesting they might also sequester defensive alkaloids from dietary sources. To test this hypothesis, fruit flies dusted with alkaloid/nutritional supplement powder were fed to individual Melanophryniscus stelzneri in two experiments. In the first experiment, the alkaloids 5,8-disubstituted indolizidine 235B' and decahydroquinoline were administered to three individuals for 104 days. In the second experiment, the alkaloids 3,5-disubstituted indolizidine 239Q and decahydroquinoline were given to three frogs for 153 days. Control frogs were fed fruit flies dusted only with nutritional supplement. Gas chromatography/mass spectrometry analyses revealed that skin secretions of all experimental frogs contained alkaloids, whereas those of all control frogs lacked alkaloids. Uptake of decahydroquinoline was greater than uptake of 5,8-disubstituted indolizidine, and uptake of 3,5-disubstituted indolizidine was greater than uptake of decahydroquinoline, suggesting greater uptake efficiency of certain alkaloids. Frogs in the second experiment accumulated a greater amount of alkaloid, which corresponds to the longer duration and greater number of alkaloid-dusted fruit flies that were consumed. These findings provide the first experimental evidence that bufonid poison frogs sequester alkaloid-based defenses from dietary

Differentiation of frog fats from vegetable and marine oils by Fourier Transform Infrared Spectroscopy and chemometric analysis

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A. N. Nina Naquiah

2015-01-01

Full Text Available The agro-based production and consumption of frogs coupled with world-wide trading have been increased in the recent years giving rise to the risk of frog fat adulteration in expensive vegetable and marine oils. For the first time, we profiled here frog fats using Fourier Transform Infrared (FTIR Spectroscopy coupled with multivariate principal component analysis (PCA. The comparison of the FTIR spectral absorbance intensities demonstrated linkage of frog fats to other edible fats and oils. Three commercially available marine oils and three vegetables oils were studied with frog fats and clear pattern of clusters with distinctive identifiable features were obtained through PCA modeling. PCA analysis identified 2922.21 cm-1, 2852.88 cm-1, 1745.45 cm-1, 1158.29 cm-1 and 721.51 cm-1 FTIR-frequencies as the most discriminating variables influencing the group separation into different clusters. This fundamental study has clear implications in the identification of frog fat from its marine and vegetable counterparts for the potential detection of frog fat adulteration in various fat and oils.

Biodiversity of frog haemoparasites from sub-tropical northern KwaZulu-Natal, South Africa

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Edward C. Netherlands

2015-04-01

Full Text Available Since South Africa boasts a high biodiversity of frog species, a multispecies haemoparasite survey was conducted by screening the blood from 29 species and 436 individual frogs. Frogs were collected at three localities in sub-tropical KwaZulu-Natal, a hotspot for frog diversity. Twenty per cent of the frogs were infected with at least one of five groups of parasites recorded. Intraerythrocytic parasites comprising Hepatozoon, Dactylosoma, and viral or bacterial organisms, as well as extracellular parasites including trypanosomes and microfilarid nematodes were found. A significant difference (P < 0.01 in the prevalence of parasitaemia was found across species, those semi-aquatic species demonstrating the highest, followed by semi-terrestrial frog species. None of those species described as purely terrestrial and aquatic were infected. Hepatozoon and Trypanosoma species accounted for most of the infections, the former demonstrating significant differences in intensity of infection across species, families and habitat types (P = 0.028; P = 0.006; P = 0.007 respectively. Per locality, the first, the formally protected Ndumo Game Reserve, had the highest biodiversity of haemoparasite infections, with all five groups of parasites recorded. The other two sites, that is the area bordering the reserve and the Kwa Nyamazane Conservancy, had a lower diversity with no parasite infections recorded and only Hepatozoon species recorded respectively. Such findings could be ascribed to the anthropogenic impact on the latter two sites, the first by the rural village activities, and the second by the bordering commercial sugar cane agriculture. Future studies should include both morphological and molecular descriptions of the above parasites, as well as the identification of potential vectors, possibly clarifying the effects human activities may have on frog haemoparasite life cycles and as such their biodiversity.

Evaluation of use of tiletamine/zolazepam for anesthesia of bullfrogs and leopard frogs.

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Letcher, J; Durante, R

1995-07-01

Use of tiletamine hydrochloride and zolazepam hydrochloride (1:1 fixed ratio combination) as an anesthetic agent in 2 anuran species was studied. A dosage of 5 mg/kg of body weight, administered IM, resulted in variable weak tranquilization. Intramuscular administration at dosages of 10 and 20 mg/kg induced variable states of tranquilization or anesthesia in leopard frogs (Rana pipiens) and bullfrogs (R catesbeiana). The dosages of 50 mg/kg induced anesthesia with greater consistency than lower dosages in bullfrogs, but resulted in mortalities. The same dosage was uniformly fatal in leopard frogs. Neither gross nor histologic lesions were identified in the frogs that died. Depth and duration of anesthesia was dosage related. At the 20 and 50 mg/kg dosages, leopard frogs attained a greater depth of anesthesia and remained anesthetized for a significantly greater duration than did bullfrogs; however, at the 5 and 10 mg/kg dosages, bullfrogs developed greater tranquilization for longer periods than did leopard frogs. Results of this study revealed profound intraspecies variation in depth and duration of effect of tiletamine/zolazepam; therefore, the drug does not appear to be a suitable injectable anesthetic in anurans.

Museum material reveals a frog parasite emergence after the invasion of the cane toad in Australia

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Phalen David N

2010-06-01

Full Text Available Abstract Background A parasite morphologically indistinguishable from Myxidium immersum (Myxozoa: Myxosporea found in gallbladders of the invasive cane toad (Bufo marinus was identified in Australian frogs. Because no written record exists for such a parasite in Australian endemic frogs in 19th and early 20th century, it was assumed that the cane toad introduced this parasite. While we cannot go back in time ourselves, we investigated whether material at the museum of natural history could be used to retrieve parasites, and whether they were infected at the time of their collection (specifically prior to and after the cane toad translocation to Australia in 1935. Results Using the herpetological collection at the Australian Museum we showed that no myxospores were found in any animals (n = 115 prior to the cane toad invasion (1879-1935. The green and golden bell frog (Litoria aurea, the Peron's tree frog (Litoria peronii, the green tree frog (Litoria caerulea and the striped marsh frog (Limnodynastes peronii were all negative for the presence of the parasite using microscopy of the gallbladder content and its histology. These results were sufficient to conclude that the population was free from this disease (at the expected minimum prevalence of 5% at 99.7% confidence level using the 115 voucher specimens in the Australian Museum. Similarly, museum specimens (n = 29 of the green and golden bell frog from New Caledonia, where it was introduced in 19th century, did not show the presence of myxospores. The earliest specimen positive for myxospores in a gallbladder was a green tree frog from 1966. Myxospores were found in eight (7.1%, n = 112 frogs in the post cane toad introduction period. Conclusion Australian wildlife is increasingly under threat, and amphibian decline is one of the most dramatic examples. The museum material proved essential to directly support the evidence of parasite emergence in Australian native frogs. This parasite can be

Habitat selection, movement patterns, and hazards encountered by northern leopard frogs (Lithobates pipiens) in an agricultural landscape

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Knutson, Melinda G.; Herner-Thogmartin, Jennifer H.; Thogmartin, Wayne E.; Kapfer, Joshua M.; Nelson, John

2018-01-01

Telemetry data for 59 Northern Leopard Frogs (Lithobates pipiens) breeding in ponds in Houston and Winona Counties, MN; 2001-2002. Agricultural intensification is causing declines in many wildlife species, including Northern Leopard Frogs (Lithobates pipiens). Specific information about frog movements, habitat selection, and sources of mortality can be used to inform conservation-focused land management and acquisition. We studied Northern Leopard Frogs in southeastern Minnesota, part of the Driftless Area ecoregion, characterized by hills and valleys and a mix of agriculture, forests, small towns and farmsteads. In this area, small farm ponds, originally built to control soil erosion are used by the species for breeding and wintering in addition to riparian wetlands. But, this agricultural landscape may be hazardous for frogs moving between breeding, feeding, and wintering habitats. We surgically implanted transmitters into the peritoneal cavity of 59 Northern Leopard Frogs and tracked them from May to October 2001-2002. The total distance traveled by radio-tagged frogs ranged from 12 to 3316 m, the 95% home range averaged 5.3 ± 1.2 (SE) ha, and the 50% core area averaged 1.05 ± 0.3 (SE) ha. As expected, Northern Leopard Frogs selected wetlands over all other land cover classes and row crops were generally avoided at all levels of selection. Only a few tracked frogs were successful at dispersing (n = 6). Most frogs attempting to disperse (n =31) ended up missing (n = 14), died due to mowing (n = 8), or were recorded as transmitter failure (n = 2) or unknown mortalities (n = 1). For the conservation of Northern Leopard Frogs in this agricultural setting, we must consider both the aquatic and the terrestrial needs of this species. Conservation agencies that restore, manage, and acquire wetlands should consider the hazards posed by land uses adjacent to frog breeding and wintering sites and plan for movement corridors between these locations. For example

A frog's-eye view of the landscape : quantifying connectivity for fragmented amphibian populations

NARCIS (Netherlands)

Vos, C.C.

1999-01-01

The spatial habitat requirements are studied for two amphibian species: the tree frog ( Hyla arborea ) and the moor frog ( Rana arvalis ). Fragmentation, the destruction of suitable habitat, results in small fragments that are separated by

Tumor immunology viewed from alternative animal models—the Xenopus story

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Banach, Maureen; Robert, Jacques

2017-01-01

a) Purpose of review Nonmammalian comparative animal models are important not only to gain fundamental evolutionary understanding of the complex interactions of tumors with the immune system, but also to better predict the applicability of novel immunotherapeutic approaches to humans. After reviewing recent advances in developing alternative models, we focus on the amphibian Xenopus laevis and its usefulness in deciphering the perplexing roles of MHC class I-like molecules and innate (i)T cells in tumor immunity. b) Recent findings Experiments using MHC-defined inbred and cloned animals, tumor cell lines, effective reagents, sequenced genomes, and adapted gene editing techniques in Xenopus, have revealed that the critical involvement of class I-like molecules and iT cells in tumor immunity has been conserved during evolution. c) Summary Comparative studies with the X. laevis tumor immunity model can contribute to the development of better and more efficient cancer immunotherapies. PMID:28944105

Remodeling of ribosomal genes in somatic cells by Xenopus egg extract

DEFF Research Database (Denmark)

Østrup, Olga; Hyttel, Poul; Klærke, Dan Arne

2011-01-01

Extracts from Xenopus eggs can reprogram gene expression in somatic nuclei, however little is known about the earliest processes associated with the switch in the transcriptional program. We show here that an early reprogramming event is the remodeling of ribosomal chromatin and gene expression....... This occurs within hours of extract treatment and is distinct from a stress response. Egg extract elicits remodeling of the nuclear envelope, chromatin and nucleolus. Nucleolar remodeling involves a rapid and stable decrease in ribosomal gene transcription, and promoter targeting of the nucleolar remodeling...... and elicits a stress-type nuclear response. Thus, an early event of Xenopus egg extract-mediated nuclear reprogramming is the remodeling of ribosomal genes involving nucleolar remodeling complex. Condition-specific and rapid silencing of ribosomal genes may serve as a sensitive marker for evaluation...

Abundance of green tree frogs and insects in artificial canopy gaps in a bottomland hardwood forest.

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Horn, Scott; Hanula, James L.; Ulyshen, Michael D.; Kilgo, John C.

2005-01-01

Horn, Scott, James L. Hanula, Michael D. Ulyshen, and John C. Kilgo. 2005. Abundance of green tree frogs and insects in artificial canopy gaps in a bottomland hardwood forest. Am. Midl. Nat. 153:321-326. Abstract: We found more green tree frogs (Hyla cinerea) in canopy gaps than in closed canopy forest. Of the 331 green tree frogs observed, 88% were in canopy gaps. Likewise, higher numbers and biomasses of insects were captured in the open gap habitat. Flies were the most commonly collected insect group accounting for 54% of the total capture. These data suggest that one reason green tree frogs were more abundant in canopy gaps was the increased availability of prey and that small canopy gaps provide early successional habitats that are beneficial to green tree frog populations.

Effects of acute exposure to magnetic field on ionic composition of frog sciatic nerve

International Nuclear Information System (INIS)

Salem, A.; Hafedh, A.; Mohsen, S.

2004-01-01

Objective: To evaluate the possible interaction between magnetic field and cadmium on ionic composition of frog sciatic nerve. Design: The combined effect of magnetic field and cadmium (1.5mg/kg; in lymphatic sac) were studied in frog sciatic nerves (Rana Esculenta). Sciatic nerve samples were extracted, weighed and mixed in bidistilled water in order to analyze by inductively coupled plasma (ICP) ionic composition. Setting: Frogs (Rana Esculenta) were reared in swimming-pool (Faculte des Sciences de Bizerte, Tunisia). Frogs were cared for under the Tunisian Code of Practice for the Care and Use of Animals for Scientific purpose and the Experimental Protocols were approved by the Ethics Committee. Subjects: Treated and control groups (n=6) weighing 50-100g at the time of experiments were housed in the same condition three weeks before the beginning of the experiments. Results: Acute exposure to magnetic field increased significantly the calcium (+298%, p<0.05) and iron (+50%, p<0.05) contents of frog sciatic nerve, whereas magnesium and copper contents remained unchanged. The association between magnetic field and cadmium, induced marked increase of calcium (+360%, p<0.05), whereas magnesium content remained stable. Conclusions: Magnetic field exposure alters the ionic composition in the frog sciatic nerve, especially calcium and iron. Magnetic field magnifies the effect of cadmium on calcium homeostasis. (author)

Factors influencing survival and mark retention in postmetamorphic boreal chorus frogs

Science.gov (United States)

Swanson, Jennifer E; Bailey, Larissa L.; Muths, Erin L.; Funk, W. Chris

2013-01-01

The ability to track individual animals is crucial in many field studies and often requires applying marks to captured individuals. Toe clipping has historically been a standard marking method for wild amphibian populations, but more recent marking methods include visual implant elastomer and photo identification. Unfortunately, few studies have investigated the influence and effectiveness of marking methods for recently metamorphosed individuals and as a result little is known about this life-history phase for most amphibians. Our focus was to explore survival probabilities, mark retention, and mark migration in postmetamorphic Boreal Chorus Frogs (Psuedacris maculata) in a laboratory setting. One hundred forty-seven individuals were assigned randomly to two treatment groups or a control group. Frogs in the first treatment group were marked with visual implant elastomer, while frogs in the second treatment group were toe clipped. Growth and mortality were recorded for one year and resulting data were analyzed using known-fate models in Program MARK. Model selection results suggested that survival probabilities of frogs varied with time and showed some variation among marking treatments. We found that frogs with multiple toes clipped on the same foot had lower survival probabilities than individuals in other treatments, but individuals can be marked by clipping a single toe on two different feet without any mark loss or negative survival effects. Individuals treated with visual implant elastomer had a mark migration rate of 4% and mark loss rate of 6%, and also showed very little negative survival impacts relative to control individuals.

An Analysis of Predator Selection to Affect Aposematic Coloration in a Poison Frog Species.

Science.gov (United States)

Dreher, Corinna E; Cummings, Molly E; Pröhl, Heike

2015-01-01

Natural selection is widely noted to drive divergence of phenotypic traits. Predation pressure can facilitate morphological divergence, for example the evolution of both cryptic and conspicuous coloration in animals. In this context Dendrobatid frogs have been used to study evolutionary forces inducing diversity in protective coloration. The polytypic strawberry poison frog (Oophaga pumilio) shows strong divergence in aposematic coloration among populations. To investigate whether predation pressure is important for color divergence among populations of O. pumilio we selected four mainland populations and two island populations from Costa Rica and Panama. Spectrometric measurements of body coloration were used to calculate color and brightness contrasts of frogs as an indicator of conspicuousness for the visual systems of several potential predators (avian, crab and snake) and a conspecific observer. Additionally, we conducted experiments using clay model frogs of different coloration to investigate whether the local coloration of frogs is better protected than non-local color morphs, and if predator communities vary among populations. Overall predation risk differed strongly among populations and interestingly was higher on the two island populations. Imprints on clay models indicated that birds are the main predators while attacks of other predators were rare. Furthermore, clay models of local coloration were equally likely to be attacked as those of non-local coloration. Overall conspicuousness (and brightness contrast) of local frogs was positively correlated with attack rates by birds across populations. Together with results from earlier studies we conclude that conspicuousness honestly indicates toxicity to avian predators. The different coloration patterns among populations of strawberry poison frogs in combination with behavior and toxicity might integrate into equally efficient anti-predator strategies depending on local predation and other ecological

Biodiversity of frog haemoparasites from sub-tropical northern KwaZulu-Natal, South Africa

Science.gov (United States)

Netherlands, Edward C.; Cook, Courtney A.; Kruger, Donnavan J.D.; du Preez, Louis H.; Smit, Nico J.

2015-01-01

Since South Africa boasts a high biodiversity of frog species, a multispecies haemoparasite survey was conducted by screening the blood from 29 species and 436 individual frogs. Frogs were collected at three localities in sub-tropical KwaZulu-Natal, a hotspot for frog diversity. Twenty per cent of the frogs were infected with at least one of five groups of parasites recorded. Intraerythrocytic parasites comprising Hepatozoon, Dactylosoma, and viral or bacterial organisms, as well as extracellular parasites including trypanosomes and microfilarid nematodes were found. A significant difference (P Hepatozoon and Trypanosoma species accounted for most of the infections, the former demonstrating significant differences in intensity of infection across species, families and habitat types (P = 0.028; P = 0.006; P = 0.007 respectively). Per locality, the first, the formally protected Ndumo Game Reserve, had the highest biodiversity of haemoparasite infections, with all five groups of parasites recorded. The other two sites, that is the area bordering the reserve and the Kwa Nyamazane Conservancy, had a lower diversity with no parasite infections recorded and only Hepatozoon species recorded respectively. Such findings could be ascribed to the anthropogenic impact on the latter two sites, the first by the rural village activities, and the second by the bordering commercial sugar cane agriculture. Future studies should include both morphological and molecular descriptions of the above parasites, as well as the identification of potential vectors, possibly clarifying the effects human activities may have on frog haemoparasite life cycles and as such their biodiversity. PMID:25830113

Diversity within diversity: Parasite species richness in poison frogs assessed by transcriptomics.

Science.gov (United States)

Santos, Juan C; Tarvin, Rebecca D; O'Connell, Lauren A; Blackburn, David C; Coloma, Luis A

2018-08-01

Symbionts (e.g., endoparasites and commensals) play an integral role in their host's ecology, yet in many cases their diversity is likely underestimated. Although endoparasites are traditionally characterized using morphology, sequences of conserved genes, and shotgun metagenomics, host transcriptomes constitute an underused resource to identify these organisms' diversity. By isolating non-host transcripts from host transcriptomes, individual host tissues can now simultaneously reveal their endoparasite species richness (i.e., number of different taxa) and provide insights into parasite gene expression. These approaches can be used in host taxa whose endoparasites are mostly unknown, such as those of tropical amphibians. Here, we focus on the poison frogs (Dendrobatidae) as hosts, which are a Neotropical clade known for their bright coloration and defensive alkaloids. These toxins are an effective protection against vertebrate predators (e.g., snakes and birds), bacteria, and skin-biting ectoparasites (e.g., mosquitoes); however, little is known about their deterrence against eukaryotic endoparasites. With de novo transcriptomes of dendrobatids, we developed a bioinformatics pipeline for endoparasite identification that uses host annotated RNA-seq data and set of a priori parasite taxonomic terms, which are used to mine for specific endoparasites. We found a large community of helminths and protozoans that were mostly restricted to the digestive tract and a few systemic parasites (e.g., Trypanosoma). Contrary to our expectations, all dendrobatid frogs regardless of the presence of alkaloid defenses have endoparasites, with their highest species richness located in the frog digestive tract. Some of these organisms (e.g., roundworms) might prove to be generalists, as they were not found to be co-diversifying with their frog hosts. We propose that endoparasites may escape poison frogs' chemical defenses by colonizing tissues with fewer alkaloids than the frog's skin

Discovery of skin alkaloids in a miniaturized eleutherodactylid frog from Cuba.

Science.gov (United States)

Rodríguez, Ariel; Poth, Dennis; Schulz, Stefan; Vences, Miguel

2011-06-23

Four phylogenetically independent lineages of frogs are currently known to sequester lipid-soluble skin alkaloids for which a dietary source has been demonstrated. We report here a remarkable fifth such instance, in Eleutherodactylus iberia and Eleutherodactylus orientalis, two species of miniaturized frogs of the family Eleutherodactylidae from Cuba. Six pumiliotoxins and two indolizidines were found in E. iberia, one of the smallest frogs in the world and characterized by a contrasting colour pattern for which we hypothesize an aposematic function. Analyses of stomach content indicated a numerical prevalence of mites with an important proportion of oribatids-a group of arthropods known to contain one of the pumiliotoxins detected in E. iberia. This suggests that miniaturization and specialization to small prey may have favoured the acquisition of dietary skin alkaloids in these amphibians.

Abundance of Green Tree Frogs and Insects in Artificial Canopy Gaps in a Bottomland Hardwood Forest.

Energy Technology Data Exchange (ETDEWEB)

Horn, Scott; Hanula, James, L.; Ulyshen, Michael D.; Kilgo, John, C.

2005-04-01

ABSTRACT - We found more green tree frogs ( Hyla cinerea) n canopv gaps than in closed canopy forest. Of the 331 green tree frogs observed, 88% were in canopv gaps. Likewise, higher numbers and biomasses of insects were captured in the open gap habitat Flies were the most commonlv collected insect group accounting for 54% of the total capture. These data suggest that one reason green tree frogs were more abundant in canopy gaps was the increased availability of prey and that small canopy gaps provide early successional habitats that are beneficial to green tree frog populations.

Introducing Environmental Toxicology in Instructional Labs: The Use of a Modified Amphibian Developmental Toxicity Assay to Support Inquiry-Based Student Projects

Science.gov (United States)

Sauterer, Roger; Rayburn, James R.

2012-01-01

Introducing students to the process of scientific inquiry is a major goal of high school and college labs. Environmental toxins are of great concern and public interest. Modifications of a vertebrate developmental toxicity assay using the frog Xenopus laevis can support student-initiated toxicology experiments that are relevant to humans. Teams of…

Food niche overlap between two sympatric leaf-litter frog species from Central Amazonia

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Leandro Talione Sabagh

2012-02-01

Full Text Available We studied the feeding habits and similarities in the diet of two sympatric and syntopic Amazonian frog species, Anomaloglossus stepheni (Aromobatidae and Leptodactylus andreae (Leptodactylidae in a forested area in Central Amazonia. The breadth of the trophic niche of these species was 5.89 and 3.75, respectively, and approximately 85% of their diets were similar. Ants were main food item in the diets of both frog species. The coexistence between these frog species may be facilitated by the significant differences in the size of their mouths. This difference allows them to consume preys items of different sizes.

Dermaseptins and Magainins: Antimicrobial Peptides from Frogs' Skin—New Sources for a Promising Spermicides Microbicides—A Mini Review

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Amira Zairi

2009-01-01

Full Text Available Sexually transmitted infections (STIs and human immunodeficiency virus (HIV, the causative agents of acquired immunodeficiency syndrome (AIDS, are two great concerns in the reproductive health of women. Thus, the challenge is to find products with a double activity, on the one hand having antimicrobial/antiviral properties with a role in the reduction of STI, and on the other hand having spermicidal action to be used as a contraceptive. In the absence of an effective microbicide along with the disadvantages of the most commonly used spermicidal contraceptive worldwide, nonoxynol-9, new emphasis has been focused on the development of more potential intravaginal microbicidal agents. Topical microbicides spermicides would ideally provide a female-controlled method of self-protection against HIV as well as preventing pregnancies. Nonoxynol-9, the only recommended microbicide spermicide, damages cervicovaginal epithelium because of its membrane-disruptive properties. Clearly, there is an urgent need to identify new compounds with dual potential microbicidal properties; antimicrobial peptides should be candidates for such investigations. Dermaseptins and magainins are two classes of cationic, amphipathic α-helical peptides that have been identified in the skin extracts of frogs Phyllomedusa sauvagei and Xenopus laevis. Regarding their contraceptive activities and their effect against various STI-causing pathogens, we believe that these two peptides are appropriate candidates in the evaluation of newer and safer microbicides spermicides in the future.

Research on moving object detection based on frog's eyes

Science.gov (United States)

Fu, Hongwei; Li, Dongguang; Zhang, Xinyuan

2008-12-01

On the basis of object's information processing mechanism with frog's eyes, this paper discussed a bionic detection technology which suitable for object's information processing based on frog's vision. First, the bionics detection theory by imitating frog vision is established, it is an parallel processing mechanism which including pick-up and pretreatment of object's information, parallel separating of digital image, parallel processing, and information synthesis. The computer vision detection system is described to detect moving objects which has special color, special shape, the experiment indicates that it can scheme out the detecting result in the certain interfered background can be detected. A moving objects detection electro-model by imitating biologic vision based on frog's eyes is established, the video simulative signal is digital firstly in this system, then the digital signal is parallel separated by FPGA. IN the parallel processing, the video information can be caught, processed and displayed in the same time, the information fusion is taken by DSP HPI ports, in order to transmit the data which processed by DSP. This system can watch the bigger visual field and get higher image resolution than ordinary monitor systems. In summary, simulative experiments for edge detection of moving object with canny algorithm based on this system indicate that this system can detect the edge of moving objects in real time, the feasibility of bionic model was fully demonstrated in the engineering system, and it laid a solid foundation for the future study of detection technology by imitating biologic vision.

Of volcanoes, saints, trash, and frogs

DEFF Research Database (Denmark)

Andersen, Astrid Oberborbeck

, at the same time as political elections and economic hardship. During one year of ethnographic fieldwork volcanoes, saints, trash and frogs were among the nonhuman entities referred to in conversations and engaged with when responding to the changes that trouble the world and everyday life of Arequipans...

An Analysis of Predator Selection to Affect Aposematic Coloration in a Poison Frog Species.

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Corinna E Dreher

Full Text Available Natural selection is widely noted to drive divergence of phenotypic traits. Predation pressure can facilitate morphological divergence, for example the evolution of both cryptic and conspicuous coloration in animals. In this context Dendrobatid frogs have been used to study evolutionary forces inducing diversity in protective coloration. The polytypic strawberry poison frog (Oophaga pumilio shows strong divergence in aposematic coloration among populations. To investigate whether predation pressure is important for color divergence among populations of O. pumilio we selected four mainland populations and two island populations from Costa Rica and Panama. Spectrometric measurements of body coloration were used to calculate color and brightness contrasts of frogs as an indicator of conspicuousness for the visual systems of several potential predators (avian, crab and snake and a conspecific observer. Additionally, we conducted experiments using clay model frogs of different coloration to investigate whether the local coloration of frogs is better protected than non-local color morphs, and if predator communities vary among populations. Overall predation risk differed strongly among populations and interestingly was higher on the two island populations. Imprints on clay models indicated that birds are the main predators while attacks of other predators were rare. Furthermore, clay models of local coloration were equally likely to be attacked as those of non-local coloration. Overall conspicuousness (and brightness contrast of local frogs was positively correlated with attack rates by birds across populations. Together with results from earlier studies we conclude that conspicuousness honestly indicates toxicity to avian predators. The different coloration patterns among populations of strawberry poison frogs in combination with behavior and toxicity might integrate into equally efficient anti-predator strategies depending on local predation and

Light-induced, GTP-binding protein mediated membrane currents of Xenopus oocytes injected with rhodopsin of cephalopods.

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Ando, H; Seidou, M; Kito, Y

1991-01-01

Xenopus oocytes that were injected with rhabdomeric membranes of squid and octopus photoreceptors acquired light sensitivity. The injected oocytes showed a light-induced current having characteristics similar to other G-protein-mediated Cl- currents induced by the activation of other membrane receptors. Pretreatment of the oocytes with pertussis toxin before the injection suppressed the generation of the light-induced current, indicating an ability of cephalopod rhodopsin to cross-react with an endogenous G-protein of Xenopus oocytes.

Metaflumizone is a novel sodium channel blocker insecticide.

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Salgado, V L; Hayashi, J H

2007-12-15

Metaflumizone is a novel semicarbazone insecticide, derived chemically from the pyrazoline sodium channel blocker insecticides (SCBIs) discovered at Philips-Duphar in the early 1970s, but with greatly improved mammalian safety. This paper describes studies confirming that the insecticidal action of metaflumizone is due to the state-dependent blockage of sodium channels. Larvae of the moth Spodoptera eridania injected with metaflumizone became paralyzed, concomitant with blockage of all nerve activity. Furthermore, tonic firing of abdominal stretch receptor organs from Spodoptera frugiperda was blocked by metaflumizone applied in the bath, consistent with the block of voltage-dependent sodium channels. Studies on native sodium channels, in primary-cultured neurons isolated from the CNS of the larvae of the moth Manduca sexta and on Para/TipE sodium channels heterologously expressed in Xenopus (African clawed frog) oocytes, confirmed that metaflumizone blocks sodium channels by binding selectively to the slow-inactivated state, which is characteristic of the SCBIs. The results confirm that metaflumizone is a novel sodium channel blocker insecticide.

Frog: Asynchronous Graph Processing on GPU with Hybrid Coloring Model

Energy Technology Data Exchange (ETDEWEB)

Shi, Xuanhua; Luo, Xuan; Liang, Junling; Zhao, Peng; Di, Sheng; He, Bingsheng; Jin, Hai

2018-01-01

GPUs have been increasingly used to accelerate graph processing for complicated computational problems regarding graph theory. Many parallel graph algorithms adopt the asynchronous computing model to accelerate the iterative convergence. Unfortunately, the consistent asynchronous computing requires locking or atomic operations, leading to significant penalties/overheads when implemented on GPUs. As such, coloring algorithm is adopted to separate the vertices with potential updating conflicts, guaranteeing the consistency/correctness of the parallel processing. Common coloring algorithms, however, may suffer from low parallelism because of a large number of colors generally required for processing a large-scale graph with billions of vertices. We propose a light-weight asynchronous processing framework called Frog with a preprocessing/hybrid coloring model. The fundamental idea is based on Pareto principle (or 80-20 rule) about coloring algorithms as we observed through masses of realworld graph coloring cases. We find that a majority of vertices (about 80%) are colored with only a few colors, such that they can be read and updated in a very high degree of parallelism without violating the sequential consistency. Accordingly, our solution separates the processing of the vertices based on the distribution of colors. In this work, we mainly answer three questions: (1) how to partition the vertices in a sparse graph with maximized parallelism, (2) how to process large-scale graphs that cannot fit into GPU memory, and (3) how to reduce the overhead of data transfers on PCIe while processing each partition. We conduct experiments on real-world data (Amazon, DBLP, YouTube, RoadNet-CA, WikiTalk and Twitter) to evaluate our approach and make comparisons with well-known non-preprocessed (such as Totem, Medusa, MapGraph and Gunrock) and preprocessed (Cusha) approaches, by testing four classical algorithms (BFS, PageRank, SSSP and CC). On all the tested applications and

Visualisation of cerebrospinal fluid flow patterns in albino Xenopus larvae in vivo

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Mogi Kazue

2012-04-01

Full Text Available Abstract Background It has long been known that cerebrospinal fluid (CSF, its composition and flow, play an important part in normal brain development, and ependymal cell ciliary beating as a possible driver of CSF flow has previously been studied in mammalian fetuses in vitro. Lower vertebrate animals are potential models for analysis of CSF flow during development because they are oviparous. Albino Xenopus laevis larvae are nearly transparent and have a straight, translucent brain that facilitates the observation of fluid flow within the ventricles. The aim of these experiments was to study CSF flow and circulation in vivo in the developing brain of living embryos, larvae and tadpoles of Xenopus laevis using a microinjection technique. Methods The development of Xenopus larval brain ventricles and the patterns of CSF flow were visualised after injection of quantum dot nanocrystals and polystyrene beads (3.1 or 5.8 μm in diameter into the fourth cerebral ventricle at embryonic/larval stages 30-53. Results The fluorescent nanocrystals showed the normal development of the cerebral ventricles from embryonic/larval stages 38 to 53. The polystyrene beads injected into stage 47-49 larvae revealed three CSF flow patterns, left-handed, right-handed and non-biased, in movement of the beads into the third ventricle from the cerebral aqueduct (aqueduct of Sylvius. In the lateral ventricles, anterior to the third ventricle, CSF flow moved anteriorly along the outer wall of the ventricle to the inner wall and then posteriorly, creating a semicircle. In the cerebral aqueduct, connecting the third and fourth cerebral ventricles, CSF flow moved rostrally in the dorsal region and caudally in the ventral region. Also in the fourth ventricle, clear dorso-ventral differences in fluid flow pattern were observed. Conclusions This is the first visualisation of the orchestrated CSF flow pattern in developing vertebrates using a live animal imaging approach. CSF flow

Water Frogs, Aquariums, and Salmonella -- Oh My!

Centers for Disease Control (CDC) Podcasts

2009-12-09

This CDC Kidtastics podcast discusses how people can get Salmonella from water frogs and aquariums.  Created: 12/9/2009 by National Center for Zoonotic, Vector-Borne, and Enteric Diseases (NCZVED).   Date Released: 12/9/2009.

Early-Life Diet Affects Host Microbiota and Later-Life Defenses Against Parasites in Frogs.

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Knutie, Sarah A; Shea, Lauren A; Kupselaitis, Marinna; Wilkinson, Christina L; Kohl, Kevin D; Rohr, Jason R

2017-10-01

Food resources can affect the health of organisms by altering their symbiotic microbiota and affecting energy reserves for host defenses against parasites. Different diets can vary in their macronutrient content and therefore they might favor certain bacterial communities of the host and affect the development and maintenance of the immune system, such as the inflammatory or antibody responses. Thus, testing the effect of diet, especially for animals with wide diet breadths, on host-associated microbiota and defenses against parasites might be important in determining infection and disease risk. Here, we test whether the early-life diet of Cuban tree frogs (Osteopilus septentrionalis) affects early- and later-life microbiota as well as later-life defenses against skin-penetrating, gut worms (Aplectana hamatospicula). We fed tadpoles two ecologically common diets: a diet of conspecifics or a diet of algae (Arthrospira sp.). We then: (1) characterized the gut microbiota of tadpoles and adults; and (2) challenged adult frogs with parasitic worms and measured host resistance (including the antibody-mediated immune response) and tolerance of infections. Tadpole diet affected bacterial communities in the guts of tadpoles but did not have enduring effects on the bacterial communities of adults. In contrast, tadpole diet had enduring effects on host resistance and tolerance of infections in adult frogs. Frogs that were fed a conspecific-based diet as tadpoles were more resistant to worm penetration compared with frogs that were fed an alga-based diet as tadpoles, but less resistant to worm establishment, which may be related to their suppressed antibody response during worm establishment. Furthermore, frogs that were fed a conspecific-based diet as tadpoles were more tolerant to the effect of parasite abundance on host mass during worm establishment. Overall, our study demonstrates that the diet of Cuban tree frog tadpoles affects the gut microbiota and defenses against

A success model and implementation on examining teacher’s attitude in using frog virtual learning environment

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Wan Rozaini Sheik Osman

2017-12-01

Full Text Available The Frog Virtual Learning Environment (Frog VLE together with school administrators, teachers, students and parents has formed the concept of a virtual community within the school environment. The research uses a qualitative approach that involves interviewing four selected teachers in a primary school located in the district of Baling/ Sik, Kedah. The study employs a structured questionnaire as an interview protocol instrument. The questionnaires were also distributed to sixteen other teachers to compare the responses. The findings showed that teachers were using Frog VLE application and it helps in teaching and learning. Frog VLE also motivates teachers to teach better. However, not all teachers are comfortable using it because there are many obstacles and constraints that teachers face when applying them. The analysis of result from the teacher’s attitude indicated that there was an important relationship between the teacher’s basic knowledge of ICT and the skills in accessing the Frog VLE.

Transgenic Xenopus laevis Line for In Vivo Labeling of Nephrons within the Kidney

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Mark E. Corkins

2018-04-01

Full Text Available Xenopus laevis embryos are an established model for studying kidney development. The nephron structure and genetic pathways that regulate nephrogenesis are conserved between Xenopus and humans, allowing for the study of human disease-causing genes. Xenopus embryos are also amenable to large-scale screening, but studies of kidney disease-related genes have been impeded because assessment of kidney development has largely been limited to examining fixed embryos. To overcome this problem, we have generated a transgenic line that labels the kidney. We characterize this cdh17:eGFP line, showing green fluorescent protein (GFP expression in the pronephric and mesonephric kidneys and colocalization with known kidney markers. We also demonstrate the feasibility of live imaging of embryonic kidney development and the use of cdh17:eGFP as a kidney marker for secretion assays. Additionally, we develop a new methodology to isolate and identify kidney cells for primary culture. We also use morpholino knockdown of essential kidney development genes to establish that GFP expression enables observation of phenotypes, previously only described in fixed embryos. Taken together, this transgenic line will enable primary kidney cell culture and live imaging of pronephric and mesonephric kidney development. It will also provide a simple means for high-throughput screening of putative human kidney disease-causing genes.

Anosmin-1 is essential for neural crest and cranial placodes formation in Xenopus.

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Bae, Chang-Joon; Hong, Chang-Soo; Saint-Jeannet, Jean-Pierre

2018-01-15

During embryogenesis vertebrates develop a complex craniofacial skeleton associated with sensory organs. These structures are primarily derived from two embryonic cell populations the neural crest and cranial placodes, respectively. Neural crest cells and cranial placodes are specified through the integrated action of several families of signaling molecules, and the subsequent activation of a complex network of transcription factors. Here we describe the expression and function of Anosmin-1 (Anos1), an extracellular matrix protein, during neural crest and cranial placodes development in Xenopus laevis. Anos1 was identified as a target of Pax3 and Zic1, two transcription factors necessary and sufficient to generate neural crest and cranial placodes. Anos1 is expressed in cranial neural crest progenitors at early neurula stage and in cranial placode derivatives later in development. We show that Anos1 function is required for neural crest and sensory organs development in Xenopus, consistent with the defects observed in Kallmann syndrome patients carrying a mutation in ANOS1. These findings indicate that anos1 has a conserved function in the development of craniofacial structures, and indicate that anos1-depleted Xenopus embryos represent a useful model to analyze the pathogenesis of Kallmann syndrome. Copyright © 2017. Published by Elsevier Inc.

COMPARATIVE ACTIVITY OF CECROPIN A AND POLYMYXIN B AGAINST FROG BACTERIAL PATHOGENS

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Ermin Schadich

2013-03-01

Full Text Available The antimicrobial activity of two antimicrobial peptides, cecropin A and polymyxin B against different bacterial pathogens associated with bacterial dermatosepticemia, a fatal bacterial infectious disease of frogs was investigated. The peptides were tested in serial of concentrations (100-0.19 µg/ml for growth inhibition of seven pathogens: Aeromonas hydrophila, Chryseobacterium meningosepticum, Citrobacter freundii, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus mirabilis and Serratia liquefaciens. Their antimicrobial activity was compared with that of two antimicrobial peptides from frog skin, magainin 2 and aurein 2.1. Both cecropin A and polymyxin B, completely inhibited the growth of three pathogens: C. freundii, K. pneumoniae and P. aeruginosa at a concentration some sixteen times less than two skin peptides. Furthermore, cecropin A inhibited the growth of three pathogens resistant to the two skin peptides, A. hydrophila, C. meningosepticum and P. mirabilis. Polymyxin B also inhibited the growth of three pathogens resistant to the skin peptides, A. hydrophila, C. meningosepticum and S. liquefaciens. Cecropin A and polymyxin B have marked antibacterial activity against different frog bacterial pathogens indicating potential for therapeutic measures.Keywords: frogs, antimicrobial, bacteria, cecropin, polymyxin, resistance

Cortical Isolation from Xenopus laevis Oocytes and Eggs.

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Sive, Hazel L; Grainger, Robert M; Harland, Richard M

2007-06-01

INTRODUCTIONIn Xenopus laevis, the cortex is the layer of gelatinous cytoplasm that lies just below the plasma membrane of the egg. Rotation of the cortex relative to the deeper cytoplasm soon after fertilization is intimately linked to normal dorsal axis specification. The cortex can be dissected from the egg to analyze its composition and activity or to clone associated RNAs. This protocol describes a procedure for isolating the vegetal cortex of the fertilized egg.

Habitat use and home range of the endangered gold-spotted pond frog (Rana chosenica).

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Ra, Nam-Yong; Sung, Ha-Cheol; Cheong, Seokwan; Lee, Jung-Hyun; Eom, Junho; Park, Daesik

2008-09-01

Because of their complex life styles, amphibians and reptiles living in wetlands require both aquatic and terrestrial buffer zones in their protected conservation areas. Due to steep declines in wild populations, the gold-spotted pond frog (Rana chosenica) is listed as vulnerable by the IUCN. However, lack of data about its movements and use of habitat prevents effective conservation planning. To determine the habitat use and home range of this species, we radio-tracked 44 adult frogs for 37 days between 10 July and 4 Nov. 2007 to observe three different populations in the breeding season, non-breeding season, and late fall. The gold-spotted pond frog was very sedentary; its daily average movement was 9.8 m. Frogs stayed close to breeding ponds (within 6.6 m), and did not leave damp areas surrounding these ponds, except for dormancy migration to terrestrial sites such as dried crop fields. The average distance of dormancy migration of seven frogs from the edge of their breeding ponds was 32.0 m. The average size of an individual's home range was 713.8 m(2) (0.07 ha). The year-round population home range, which accounts for the home ranges of a population of frogs, was determined for two populations to be 8,765.0 m(2) (0.88 ha) and 3,700.9 m(2) (0.37 ha). Our results showed that to conserve this endangered species, appropriately sized wetlands and extended terrestrial buffer areas surrounding the wetlands (at least 1.33 ha, diameter 130 m) should be protected.

The potential effects of climate change on the status of Seychelles frogs (Anura: Sooglossidae

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J. Gerlach

2011-11-01

Full Text Available The status of the Seychelles frogs of the family Sooglossidae was investigated, using monitoring data from 1993-2010, climate data from 1998-2010 and studies of populations and local climate effects. Climate monitoring at each plot covered rainfall and temperature, with leaf wetness and soil moisture being monitored additionally at one site. Analysis of the data and ecological modelling of the distribution identify geographical patterns in climate which explain the present distribution of the different sooglossid species. In addition it identifies a drying trend in the first quarter of the year which corresponds to frog population declines in mid-altitude forests. This is interpreted as evidence of an ongoing deterioration in the suitability of habitats for the frogs, with declines recorded in areas of marginal suitability. By extension it is assumed that currently optimal frog habitat is also undergoing a decline in suitability, due to early year decreases in moisture. Projected changes in climate were used to predict changes in ranges of the sooglossids over the next 90 years. This predicts significant declines, with the possible extinction of the palm frog Sooglossus pipilodryas by 2100. Accordingly all four sooglossid species should be categorised as Endangered, rather than their current status of Vulnerable. Captive assurance colonies have not been successfully established to date. Captive groups have been maintained with a high degree of success but breeding has not been recorded so far. Further work needed for the conservation of the frogs is outlined: development of a reliable method of monitoring the cryptic S. thomasseti and development of captive breeding techniques.

The B-subdomain of the Xenopus laevis XFIN KRAB-AB domain is responsible for its weaker transcriptional repressor activity compared to human ZNF10/Kox1.

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Born, Nadine; Thiesen, Hans-Jürgen; Lorenz, Peter

2014-01-01

The Krüppel-associated box (KRAB) domain interacts with the nuclear hub protein TRIM28 to initiate or mediate chromatin-dependent processes like transcriptional repression, imprinting or suppression of endogenous retroviruses. The prototype KRAB domain initially identified in ZNF10/KOX1 encompasses two subdomains A and B that are found in hundreds of zinc finger transcription factors studied in human and murine genomes. Here we demonstrate for the first time transcriptional repressor activity of an amphibian KRAB domain. After sequence correction, the updated KRAB-AB domain of zinc finger protein XFIN from the frog Xenopus laevis was found to confer transcriptional repression in reporter assays in Xenopus laevis A6 kidney cells as well as in human HeLa, but not in the minnow Pimephales promelas fish cell line EPC. Binding of the XFIN KRAB-AB domain to human TRIM28 was demonstrated in a classical co-immunoprecipitation approach and visualized in a single-cell compartmentalization assay. XFIN-AB displayed reduced potency in repression as well as lower strength of interaction with TRIM28 compared to ZNF10 KRAB-AB. KRAB-B subdomain swapping between the two KRAB domains indicated that it was mainly the KRAB-B subdomain of XFIN that was responsible for its lower capacity in repression and binding to human TRIM28. In EPC fish cells, ZNF10 and XFIN KRAB repressor activity could be partially restored to low levels by adding exogenous human TRIM28. In contrast to XFIN, we did not find any transcriptional repression activity for the KRAB-like domain of human PRDM9 in HeLa cells. PRDM9 is thought to harbor an evolutionary older domain related to KRAB whose homologs even occur in invertebrates. Our results support the notion that functional bona fide KRAB domains which confer transcriptional repression and interact with TRIM28 most likely co-evolved together with TRIM28 at the beginning of tetrapode evolution.

Pesticide concentrations in frog tissue and wetland habitats in alandscape dominated by agriculture

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Smalling, Kelly L.; Reeves, Rebecca; Muths, Erin L.; Vandever, Mark W.; Battaglin, William A.; Hladik, Michelle; Pierce, Clay L.

2015-01-01

Habitat loss and exposure to pesticides are likely primary factors contributing to amphibian decline in agricultural landscapes. Conservation efforts have attempted to restore wetlands lost through landscape modifications to reduce contaminant loads in surface waters and providing quality habitat to wildlife. The benefits of this increased wetland area, perhaps especially for amphibians, may be negated if habitat quality is insufficient to support persistent populations. We examined the presence of pesticides and nutrients in water and sediment as indicators of habitat quality and assessed the bioaccumulation of pesticides in the tissue of two native amphibian species Pseudacris maculata (chorus frogs) and Lithobates pipiens (leopard frogs) at six wetlands (3 restored and 3 reference) in Iowa, USA. Restored wetlands are positioned on the landscape to receive subsurface tile drainage water while reference wetlands receive water from overland run-off and shallow groundwater sources. Concentrations of the pesticides frequently detected in water and sediment samples were not different between wetland types. The median concentration of atrazine in surface water was 0.2 μg/L. Reproductive abnormalities in leopard frogs have been observed in other studies at these concentrations. Nutrient concentrations were higher in the restored wetlands but lower than concentrations thought lethal to frogs. Complex mixtures of pesticides including up to 8 fungicides, some previously unreported in tissue, were detected with concentrations ranging from 0.08 to 1500 μg/kg wet weight. No significant differences in pesticide concentrations were observed between species, although concentrations tended to be higher in leopard frogs compared to chorus frogs, possibly because of differences in life histories. Our results provide information on habitat quality in restored wetlands that will assist state and federal agencies, landowners, and resource managers in identifying and

Xenopus laevis embryos and tadpoles as models for testing for ...

African Journals Online (AJOL)

The toxicity of bio available Zn, Cu, Pb, and Cd on the life stages of Xenopus laevis embryos and tadpoles was investigated. Cu and Cd were found to affect the hatching success of the embryos, with a strong negative relationship existing between the increase in Cu concentrations and the hatching of the embryos.

Asplenium bird’s nest ferns in rainforest canopies are climate-contingent refuges for frogs

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Brett R. Scheffers

2014-12-01

Full Text Available Epiphytes are important for canopy dwelling organisms because they provide a cool and moist microhabitat in the relatively hot and dry canopy. Here we examine whether epiphytic Asplenium ferns act as important habitats for arboreal frogs. We conducted extensive fern and habitat surveys for frogs in the Philippines, and complimented these surveys with roaming day and night canopy surveys to identify the full extent of habitat use across the vertical strata. We artificially dried ferns of various sizes to identify relationships between water and temperature buffering. Ferns are the preferred diurnal microhabitat and breeding habitat for arboreal frogs. A strong positive relationship exists between fern size and frog usage and abundance. Our drying experiments show that large ferns buffer maximum temperatures and reduce variability in temperatures, and buffering is directly linked to their hydration. Frogs are likely using large ferns for their moist, cool, environments for breeding and daytime retreat, which supports the buffered microhabitat hypothesis—these plants promote species coexistence through habitat creation and amelioration of physical stress. However, drying experiments suggest that this buffering is contingent on regular rainfall. Altered rainfall regimes could lead to the unexpected loss of the functional capacity of these important fern habitats. Keywords: Climate change, Functionality, Microhabitat, Refuge, Ectotherm, Precipitation

ICE on the road to auditory sensitivity reduction and sound localization in the frog.

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Narins, Peter M

2016-10-01

Frogs and toads are capable of producing calls at potentially damaging levels that exceed 110 dB SPL at 50 cm. Most frog species have internally coupled ears (ICE) in which the tympanic membranes (TyMs) communicate directly via the large, permanently open Eustachian tubes, resulting in an inherently directional asymmetrical pressure-difference receiver. One active mechanism for auditory sensitivity reduction involves the pressure increase during vocalization that distends the TyM, reducing its low-frequency airborne sound sensitivity. Moreover, if sounds generated by the vocal folds arrive at both surfaces of the TyM with nearly equal amplitudes and phases, the net motion of the eardrum would be greatly attenuated. Both of these processes appear to reduce the motion of the frog's TyM during vocalizations. The implications of ICE in amphibians with respect to sound localizations are discussed, and the particularly interesting case of frogs that use ultrasound for communication yet exhibit exquisitely small localization jump errors is brought to light.

Convergent Substitutions in a Sodium Channel Suggest Multiple Origins of Toxin Resistance in Poison Frogs.

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Tarvin, Rebecca D; Santos, Juan C; O'Connell, Lauren A; Zakon, Harold H; Cannatella, David C

2016-04-01

Complex phenotypes typically have a correspondingly multifaceted genetic component. However, the genotype-phenotype association between chemical defense and resistance is often simple: genetic changes in the binding site of a toxin alter how it affects its target. Some toxic organisms, such as poison frogs (Anura: Dendrobatidae), have defensive alkaloids that disrupt the function of ion channels, proteins that are crucial for nerve and muscle activity. Using protein-docking models, we predict that three major classes of poison frog alkaloids (histrionicotoxins, pumiliotoxins, and batrachotoxins) bind to similar sites in the highly conserved inner pore of the muscle voltage-gated sodium channel, Nav1.4. We predict that poison frogs are somewhat resistant to these compounds because they have six types of amino acid replacements in the Nav1.4 inner pore that are absent in all other frogs except for a distantly related alkaloid-defended frog from Madagascar, Mantella aurantiaca. Protein-docking models and comparative phylogenetics support the role of these replacements in alkaloid resistance. Taking into account the four independent origins of chemical defense in Dendrobatidae, phylogenetic patterns of the amino acid replacements suggest that 1) alkaloid resistance in Nav1.4 evolved independently at least seven times in these frogs, 2) variation in resistance-conferring replacements is likely a result of differences in alkaloid exposure across species, and 3) functional constraint shapes the evolution of the Nav1.4 inner pore. Our study is the first to demonstrate the genetic basis of autoresistance in frogs with alkaloid defenses. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Hyperolius argus (Anura) in Natal: taxonomy, biogeography and ...

African Journals Online (AJOL)

South African frogs of the genus. Hyperolius in the Museum of Comparative Zoology,. Cambridge, Massachusetts. Ann. Transv. Mus. 20: 283 - 291. PARKER, H.W. 1930. A collection of frogs from Portuguese East. Africa. Proc. zool. Soc. Lond. 1930: 897 - 905. PASSMORE, N.I. & CARRUTHERS, V.C. 1979. South African.

FROG ASSEMBLAGE ASSOCIATED WITH BROMELIADS IN A SANDY COASTAL PLAIN IN THE STATE OF ESPÍRITO SANTO, SOUTHEASTERN BRAZIL

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MARCIO MARQUES MAGESKI

Full Text Available ABSTRACT Amphibians may use bromeliads for reproduction (i.e., bromeligenous species or only for refuge and foraging (i.e., bromelicolous species. The partition of bromeliad resources is essential to maintain the coexistence of the associated assemblages. We sampled 913 bromeliads in a sandy coastal plain (i.e., restinga habitat in southeastern Brazil and found 234 frogs belonging to seven species. One of the frog species was bromeligenous and the other six were facultative bromelicolous. The bromeliads of the genus Aechmea were the most frequently used by frogs. The low degree of frog occupancy of bromeliads (26% suggests habitat segregation. Our study highlights the importance of maintenance of bromeliad species for conservation of the associated frog assemblages.

Islet-1 is required for ventral neuron survival in Xenopus

International Nuclear Information System (INIS)

Shi, Yu; Zhao, Shuhua; Li, Jiejing; Mao, Bingyu

2009-01-01

Islet-1 is a LIM domain transcription factor involved in several processes of embryonic development. Xenopus Islet-1 (Xisl-1) has been shown to be crucial for proper heart development. Here we show that Xisl-1 and Xisl-2 are differentially expressed in the nervous system in Xenopus embryos. Knock-down of Xisl-1 by specific morpholino leads to severe developmental defects, including eye and heart failure. Staining with the neuronal markers N-tubulin and Xisl-1 itself reveals that the motor neurons and a group of ventral interneurons are lost in the Xisl-1 morphants. Terminal dUTP nick-end labeling (TUNEL) analysis shows that Xisl-1 morpholino injection induces extensive apoptosis in the ventral neural plate, which can be largely inhibited by the apoptosis inhibitor M50054. We also find that over-expression of Xisl-1 is able to promote cell proliferation and induce Xstat3 expression in the injected side, suggesting a potential role for Xisl-1 in the regulation of cell proliferation in co-operation with the Jak-Stat pathway.

How does the Xenopus laevis embryonic cell cycle avoid spatial chaos?

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Gelens, Lendert; Huang, Kerwyn Casey; Ferrell, James E.

2015-01-01

Summary Theoretical studies have shown that a deterministic biochemical oscillator can become chaotic when operating over a sufficiently large volume, and have suggested that the Xenopus laevis cell cycle oscillator operates close to such a chaotic regime. To experimentally test this hypothesis, we decreased the speed of the post-fertilization calcium wave, which had been predicted to generate chaos. However, cell divisions were found to develop normally and eggs developed into normal tadpoles. Motivated by these experiments, we carried out modeling studies to understand the prerequisites for the predicted spatial chaos. We showed that this type of spatial chaos requires oscillatory reaction dynamics with short pulse duration, and postulated that the mitotic exit in Xenopus laevis is likely slow enough to avoid chaos. In systems with shorter pulses, chaos may be an important hazard, as in cardiac arrhythmias, or a useful feature, as in the pigmentation of certain mollusk shells. PMID:26212326

Acute Toxicity of a Heavy Metal Cadmium to an Anuran, the Indian Skipper Frog Rana cyanophlyctis

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Ajai Kumar Srivastav

2016-08-01

Full Text Available Background: There has been increasing awareness throughout the world regarding the remarkable decrease in amphibian population. For such amphibian population decline several causes have been given. Cadmium, a heavy metal is released both from natural sources (leaching of cadmium rich soils and anthropogenic activities to the aquatic and terrestrial environments. This study evaluated the toxicity of heavy metal cadmium to Indian skipper frog Rana cyanophlyctis. Methods: For the determination of LC50 values for cadmium, four-day static renewal acute toxicity test was used. Five replicates each containing ten frogs were subjected to each concentration of cadmium chloride (15, 20, 25, 30, 35, 40, 45 and 50 mg/L. At different exposure periods (24, 48, 72 and 96 h, the mortality of the frog was subjected to Probit analysis with the POLO-PC software (LeOra Software to calculate the LC50 and 95% confidence level. Results: The LC50 values of cadmium chloride for the frog R. cyanophlyctis at 24, 48, 72, and 96 h are 32.586, 29.994, 27.219 and 23.048 mg/L, respectively. The results have been discussed with the toxicity reported for other aquatic vertebrate --fish. Conclusion: Cadmium caused mortality to the frog and this could be one of the reasons for population decline of frogs which inhabit water contaminated with heavy metals.

XenDB: Full length cDNA prediction and cross species mapping in Xenopus laevis

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Giegerich Robert

2005-09-01

Full Text Available Abstract Background Research using the model system Xenopus laevis has provided critical insights into the mechanisms of early vertebrate development and cell biology. Large scale sequencing efforts have provided an increasingly important resource for researchers. To provide full advantage of the available sequence, we have analyzed 350,468 Xenopus laevis Expressed Sequence Tags (ESTs both to identify full length protein encoding sequences and to develop a unique database system to support comparative approaches between X. laevis and other model systems. Description Using a suffix array based clustering approach, we have identified 25,971 clusters and 40,877 singleton sequences. Generation of a consensus sequence for each cluster resulted in 31,353 tentative contig and 4,801 singleton sequences. Using both BLASTX and FASTY comparison to five model organisms and the NR protein database, more than 15,000 sequences are predicted to encode full length proteins and these have been matched to publicly available IMAGE clones when available. Each sequence has been compared to the KOG database and ~67% of the sequences have been assigned a putative functional category. Based on sequence homology to mouse and human, putative GO annotations have been determined. Conclusion The results of the analysis have been stored in a publicly available database XenDB http://bibiserv.techfak.uni-bielefeld.de/xendb/. A unique capability of the database is the ability to batch upload cross species queries to identify potential Xenopus homologues and their associated full length clones. Examples are provided including mapping of microarray results and application of 'in silico' analysis. The ability to quickly translate the results of various species into 'Xenopus-centric' information should greatly enhance comparative embryological approaches. Supplementary material can be found at http://bibiserv.techfak.uni-bielefeld.de/xendb/.

Reciprocal Trophic Interactions and Transmission of Blood Parasites between Mosquitoes and Frogs

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Todd G. Smith

2012-04-01

Full Text Available The relationship between mosquitoes and their amphibian hosts is a unique, reciprocal trophic interaction. Instead of a one-way, predator-prey relationship, there is a cyclical dance of avoidance and attraction. This has prompted spatial and temporal synchrony between organisms, reflected in emergence time of mosquitoes in the spring and choice of habitat for oviposition. Frog-feeding mosquitoes also possess different sensory apparatuses than do their mammal-feeding counterparts. The reciprocal nature of this relationship is exploited by various blood parasites that use mechanical, salivary or trophic transmission to pass from mosquitoes to frogs. It is important to investigate the involvement of mosquitoes, frogs and parasites in this interaction in order to understand the consequences of anthropogenic actions, such as implementing biocontrol efforts against mosquitoes, and to determine potential causes of the global decline of amphibian species.

Discovery of alien water frogs (gen. Pelophylax in Umbria, with first report of P. shqipericus for Italy

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Dario Domeneghetti

2013-12-01

Full Text Available Allochthonous water frogs (gen. Pelophylax have been repeatedly introduced in several European countries, causing dramatic consequences for the conservation of indigenous taxa. In Italy, invasive populations are known for northern regions, where they were introduced mainly for edible and scientific purposes. Here, we report the first detection of an alien population of water frogs in Central Italy, along the Resina valley (Umbria. Genetic analysis of the mitochondrial ND3 gene polymorphism assigned some specimens to two different Pelophylax ridibundus clades widespread in Central and Eastern Europe. By contrast, two samples matched the mitochondrial DNA (mtDNA sequence of Pelophylax lessonae bergeri, an autochthonous taxon widespread in Central Italy, suggesting possible hybridization between alien and indigenous frogs. Finally, the specific haplotype of Pelophylax shqipericus, the Albanian Pool Frog, was also identified according to mtDNA polymorphism. This record, firstly reported for Italy, poses concerns for the conservation of this cryptic taxon, suggesting that international water frog trade may involve also particularly endangered species.

Structure and expression of the Xenopus retinoblastoma gene.

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Destrée, O H; Lam, K T; Peterson-Maduro, L J; Eizema, K; Diller, L; Gryka, M A; Frebourg, T; Shibuya, E; Friend, S H

1992-09-01

We have cloned a Xenopus homology (XRb1) of the human retinoblastoma susceptibility gene. DNA sequence analysis shows that the XRb1 gene product is highly conserved in many regions. The leucine repeat motif and many of the potential cdc2 phosphorylation sites, as well as potential sites for other kinases, are retained. The region of the protein homologous to the SV40 T antigen binding site and the basic region directly C-terminal to the E1A binding site are all conserved. XRb1 gene expression at the RNA level was studied by Northern blot analysis. Transcripts of 4.2 and 10-kb are present as maternal RNA stores in the oocyte. While the 4.2-kb product is stable until at least the mid-blastula stage, the 10-kb transcript is selectively degraded. Between stages 11 and 13 the 10-kb transcript reappears and also a minor product of approximately 11 kb becomes apparent. Both the 4.2- and the 10-kb transcripts remain present until later stages of development and are also present in all adult tissues examined, although at differing levels. Antibodies raised against human p105Rb which recognize the protein product of the XRb1 gene, pXRb1, detect the Xenopus 99-kDa protein prior to the mid-blastula stage, but at lower levels than at later stages in development.

Asymmetries in Cell Division, Cell Size, and Furrowing in the Xenopus laevis Embryo.

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Tassan, Jean-Pierre; Wühr, Martin; Hatte, Guillaume; Kubiak, Jacek

2017-01-01

Asymmetric cell divisions produce two daughter cells with distinct fate. During embryogenesis, this mechanism is fundamental to build tissues and organs because it generates cell diversity. In adults, it remains crucial to maintain stem cells. The enthusiasm for asymmetric cell division is not only motivated by the beauty of the mechanism and the fundamental questions it raises, but has also very pragmatic reasons. Indeed, misregulation of asymmetric cell divisions is believed to have dramatic consequences potentially leading to pathogenesis such as cancers. In diverse model organisms, asymmetric cell divisions result in two daughter cells, which differ not only by their fate but also in size. This is the case for the early Xenopus laevis embryo, in which the two first embryonic divisions are perpendicular to each other and generate two pairs of blastomeres, which usually differ in size: one pair of blastomeres is smaller than the other. Small blastomeres will produce embryonic dorsal structures, whereas the larger pair will evolve into ventral structures. Here, we present a speculative model on the origin of the asymmetry of this cell division in the Xenopus embryo. We also discuss the apparently coincident asymmetric distribution of cell fate determinants and cell-size asymmetry of the 4-cell stage embryo. Finally, we discuss the asymmetric furrowing during epithelial cell cytokinesis occurring later during Xenopus laevis embryo development.

cis- and trans-acting elements of the estrogen-regulated vitellogenin gene B1 of Xenopus laevis.

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Wahli, W; Martinez, E; Corthésy, B; Cardinaux, J R

1989-01-01

Vitellogenin genes are expressed under strict estrogen control in the liver of female oviparous vertebrates. Gene transfer experiments using estrogen-responsive cells have shown that the 13 bp perfect palindromic element GGTCACTGTGACC found upstream of the Xenopus laevis vitellogenin gene A2 promoter mediates hormonal stimulation and thus, was called the estrogen-responsive element (ERE). In the Xenopus vitellogenin genes B1 and B2 there are two closely adjacent EREs with one or more base substitutions when compared to the consensus ERE GGTCANNNTGACC. On their own, these degenerated elements have only a low or no regulatory capacity at all but act together synergistically to form an estrogen-responsive unit (ERU) with the same strength as the perfect palindromic 13 bp element. Analysis of estrogen receptor binding to the gene B1 ERU revealed a cooperative interaction of receptor dimers to the two adjacent imperfect EREs which most likely explains the synergistic stimulation observed in vivo. Furthermore, a promoter activator element located between positions --113 and --42 of the gene B1 and functional in the human MCF-7 and the Xenopus B3.2 cells has been identified and shown to be involved in the high level of induced transcription activity when the ERE is placed at a distance from the promoter. Finally, a hormone-controlled in vitro transcription system derived from Xenopus liver nuclear extracts was exploited to characterize two additional novel cis-acting elements within the vitellogenin gene B1 promoter. One of them, a negative regulatory element (NRE), is responsible for repression of promoter activity in the absence of hormone. The second is related to the NF-I binding site and is required, together with the ERE, to mediate hormonal induction. Moreover, we detected three trans-acting activities in Xenopus liver nuclear extracts that interact with these regions and demonstrated that they participate in the regulation of the expression of the vitellogenin

Glycogen accumulation in normal and irradiated minced muscle autografts on frog gastrocnemius

International Nuclear Information System (INIS)

Malhotra, R.K.; Kaul, R.; Malhotra, N.

1989-01-01

Alterations induced in glycogen content and phosphorylase activity have been studied in normal and irradiated minced muscle autografts on frog gastrocnemius at days 1, 3, 5, 7, 10, 15 and 30 postgrafting. The changes observed in the glycogen content and phosphorylase activity conform to the degeneration and regeneration phases of muscle repair. An attempt has been made to explain the altered glycogen utilizing capacities of the frog skeletal muscle during its repair and regeneration. (author)

Ichthyophonus sp. (Ichthyophonae, Ichthyophonida) infection in a South American amphibian, the hylid frog Hypsiboas pulchellus.

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Borteiro, Claudio; Verdes, José Manuel; Cruz, Juan Carlos; Sabalsagaray, María Jesús; Kolenc, Francisco; Martínez Debat, Claudio; Ubilla, Martín

2015-04-01

We report infection by Ichthyophonus sp. in a South American amphibian, the hylid frog Hypsiboas pulchellus in Uruguay. This frog had a large subcutaneous mass over the urostyle and dorsal musculature comprised of parasitic cysts with mild granulomatous inflammation but otherwise appeared healthy.

The Xenopus oocyte: a model for studying the metabolic regulation of cancer cell death.

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Nutt, Leta K

2012-06-01

Abnormal metabolism and the evasion of apoptosis are both considered hallmarks of cancer. A remarkable biochemical model system, the Xenopus laevis oocyte, exhibits altered metabolism coupled to its apoptotic machinery in a similar fashion to cancer cells. This review considers the theory that these two hallmarks of cancer are coupled in tumor cells and provides strong proof that the Xenopus laevis oocyte system is an appropriate model in which to dissect the biochemical events underlying the connection between the two hallmarks. By further elucidating the mechanisms through which metabolism suppresses apoptotic machinery, we may gain a better understanding about how normal cells transform into cancer cells. Copyright © 2012 Elsevier Ltd. All rights reserved.

Use of olfactory cues by newly metamorphosed wood frogs (Lithobates sylvaticus) during emigration

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Zydlewski, Joseph D.; Popescu, Viorel D.; Brodie, Bekka S.; Hunter, Malcom L.

2012-01-01

Juvenile amphibians are capable of long-distance upland movements, yet cues used for orientation during upland movements are poorly understood. We used newly metamorphosed Wood Frogs (Lithobates sylvaticus) to investigate: (1) the existence of innate (i.e., inherited) directionality, and (2) the use of olfactory cues, specifically forested wetland and natal pond cues during emigration. In a circular arena experiment, animals with assumed innate directionality did not orient in the expected direction (suggested by previous studies) when deprived of visual and olfactory cues. This suggests that juvenile Wood Frogs most likely rely on proximate cues for orientation. Animals reared in semi-natural conditions (1500 l cattle tanks) showed a strong avoidance of forested wetland cues in two different experimental settings, although they had not been previously exposed to such cues. This finding is contrary to known habitat use by adult Wood Frogs during summer. Juvenile Wood Frogs were indifferent to the chemical signature of natal pond (cattle tank) water. Our findings suggest that management strategies for forest amphibians should consider key habitat features that potentially influence the orientation of juveniles during emigration movements, as well as adult behavior.

Modeling Sexual Selection in Túngara Frog and Rationality of Mate Choice.

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Vargas Bernal, Esteban; Sanabria Malagon, Camilo

2017-12-01

The males of the species of frogs Engystomops pustulosus produce simple and complex calls to lure females, as a way of intersexual selection. Complex calls lead males to a greater reproductive success than what simple calls do. However, the complex calls are also more attractive to their main predator, the bat Trachops cirrhosus. Therefore, as M. Ryan suggests in (The túngara frog: a study in sexual selection and communication. University of Chicago Press, Chicago, 1985), the complexity of the calls lets the frogs keep a trade-off between reproductive success and predation. In this paper, we verify this trade-off from the perspective of game theory. We first model the proportion of simple calls as a symmetric game of two strategies. We also model the effect of adding a third strategy, males that keep quiet and intercept females, which would play a role of intrasexual selection. Under the assumption that the decision of the males takes into account this trade-off between reproductive success and predation, our model reproduces the observed behavior reported in the literature with minimal assumption on the parameters. From the model with three strategies, we verify that the quiet strategy could only coexists with the simple and complex strategies if the rate at which quiet males intercept females is high, which explains the rarity of the quiet strategy. We conclude that the reproductive strategy of the male frog E. pustulosus is rational.

FoxA4 favours notochord formation by inhibiting contiguous mesodermal fates and restricts anterior neural development in Xenopus embryos.

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Murgan, Sabrina; Castro Colabianchi, Aitana Manuela; Monti, Renato José; Boyadjián López, Laura Elena; Aguirre, Cecilia E; Stivala, Ernesto González; Carrasco, Andrés E; López, Silvia L

2014-01-01

In vertebrates, the embryonic dorsal midline is a crucial signalling centre that patterns the surrounding tissues during development. Members of the FoxA subfamily of transcription factors are expressed in the structures that compose this centre. Foxa2 is essential for dorsal midline development in mammals, since knock-out mouse embryos lack a definitive node, notochord and floor plate. The related gene foxA4 is only present in amphibians. Expression begins in the blastula -chordin and -noggin expressing centre (BCNE) and is later restricted to the dorsal midline derivatives of the Spemann's organiser. It was suggested that the early functions of mammalian foxa2 are carried out by foxA4 in frogs, but functional experiments were needed to test this hypothesis. Here, we show that some important dorsal midline functions of mammalian foxa2 are exerted by foxA4 in Xenopus. We provide new evidence that the latter prevents the respecification of dorsal midline precursors towards contiguous fates, inhibiting prechordal and paraxial mesoderm development in favour of the notochord. In addition, we show that foxA4 is required for the correct regionalisation and maintenance of the central nervous system. FoxA4 participates in constraining the prospective rostral forebrain territory during neural specification and is necessary for the correct segregation of the most anterior ectodermal derivatives, such as the cement gland and the pituitary anlagen. Moreover, the early expression of foxA4 in the BCNE (which contains precursors of the whole forebrain and most of the midbrain and hindbrain) is directly required to restrict anterior neural development.

A NuRD Complex from Xenopus laevis Eggs Is Essential for DNA Replication during Early Embryogenesis

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Christo P. Christov

2018-02-01

Full Text Available DNA replication in the embryo of Xenopus laevis changes dramatically at the mid-blastula transition (MBT, with Y RNA-independent random initiation switching to Y RNA-dependent initiation at specific origins. Here, we identify xNuRD, an MTA2-containing assemblage of the nucleosome remodeling and histone deacetylation complex NuRD, as an essential factor in pre-MBT Xenopus embryos that overcomes a functional requirement for Y RNAs during DNA replication. Human NuRD complexes have a different subunit composition than xNuRD and do not support Y RNA-independent initiation of DNA replication. Blocking or immunodepletion of xNuRD inhibits DNA replication initiation in isolated nuclei in vitro and causes inhibition of DNA synthesis, developmental delay, and embryonic lethality in early embryos. xNuRD activity declines after the MBT, coinciding with dissociation of the complex and emergence of Y RNA-dependent initiation. Our data thus reveal an essential role for a NuRD complex as a DNA replication factor during early Xenopus development.

Mirror-image duplication of the primary axis and heart in Xenopus embryos by the overexpression of Msx-1 gene.

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Chen, Y; Solursh, M

1995-10-01

The Msx-1 gene (formerly known as Hox-7) is a member of a discrete subclass of homeobox-containing genes. Examination of the expression pattern of Msx-1 in murine and avian embryos suggests that this gene may be involved in the regionalization of the medio-lateral axis during earlier development. We have examined the possible functions of Xenopus Msx-1 during early Xenopus embryonic development by overexpression of the Msx-1 gene. Overexpression of Msx-1 causes a left-right mirror-image duplication of primary axial structures, including notochord, neural tube, somites, suckers, and foregut. The embryonic developing heart is also mirror-image duplicated, including looping directions and polarity. These results indicate that Msx-1 may be involved in the mesoderm formation as well as left-right patterning in the early Xenopus embryonic development.

Pesticide concentrations in frog tissue and wetland habitats in a landscape dominated by agriculture.

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Smalling, Kelly L; Reeves, Rebecca; Muths, Erin; Vandever, Mark; Battaglin, William A; Hladik, Michelle L; Pierce, Clay L

2015-01-01

Habitat loss and exposure to pesticides are likely primary factors contributing to amphibian decline in agricultural landscapes. Conservation efforts have attempted to restore wetlands lost through landscape modifications to reduce contaminant loads in surface waters and providing quality habitat to wildlife. The benefits of this increased wetland area, perhaps especially for amphibians, may be negated if habitat quality is insufficient to support persistent populations. We examined the presence of pesticides and nutrients in water and sediment as indicators of habitat quality and assessed the bioaccumulation of pesticides in the tissue of two native amphibian species Pseudacris maculata (chorus frogs) and Lithobates pipiens (leopard frogs) at six wetlands (3 restored and 3 reference) in Iowa, USA. Restored wetlands are positioned on the landscape to receive subsurface tile drainage water while reference wetlands receive water from overland run-off and shallow groundwater sources. Concentrations of the pesticides frequently detected in water and sediment samples were not different between wetland types. The median concentration of atrazine in surface water was 0.2 μg/L. Reproductive abnormalities in leopard frogs have been observed in other studies at these concentrations. Nutrient concentrations were higher in the restored wetlands but lower than concentrations thought lethal to frogs. Complex mixtures of pesticides including up to 8 fungicides, some previously unreported in tissue, were detected with concentrations ranging from 0.08 to 1,500 μg/kg wet weight. No significant differences in pesticide concentrations were observed between species, although concentrations tended to be higher in leopard frogs compared to chorus frogs, possibly because of differences in life histories. Our results provide information on habitat quality in restored wetlands that will assist state and federal agencies, landowners, and resource managers in identifying and implementing

Interference of a short-chain phospholipid with ion transport pathways in frog skin

DEFF Research Database (Denmark)

Unmack, M A; Frederiksen, O; Willumsen, N J

1997-01-01

The effects of mucosal application of the short-chain phospholipid didecanoyl-L-alpha-phosphatidylcholine (DDPC; with two saturated 10-carbon acyl chains) on active Na+ transport and transepithelial conductance (G) in the frog skin (Rana temporaria) were investigated. Active Na+ transport...... of the frog skin epithelium and opens a paracellular tight junction pathway. Both effects may be caused by incorporation of DDPC in the apical cell membrane....

Cadmium-induced oxidative stress and apoptosis in the testes of frog Rana limnocharis

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Zhang Hangjun; Cai Chenchen; Shi Cailei; Cao Hui; Han Ziliu [Department of Environmental Sciences, Hangzhou Normal University, Xuelin Road 16, Xiasha Gaojiao Dongqu, Hangzhou, Zhejiang Province, 310036 (China); Jia Xiuying, E-mail: hznujiaxiuying@126.com [Department of Environmental Sciences, Hangzhou Normal University, Xuelin Road 16, Xiasha Gaojiao Dongqu, Hangzhou, Zhejiang Province, 310036 (China)

2012-10-15

Highlights: Black-Right-Pointing-Pointer Cd can cause vacuoles and deformity of the spermatogenic cells in the frog testes. Black-Right-Pointing-Pointer Cd can result in oxidative stress in the frog testes. Black-Right-Pointing-Pointer Cd can induce significantly increase of ROS contents triggered DNA damages in the frog testes. Black-Right-Pointing-Pointer Cd can cause apoptosis in the testes of male R. limnocharis. Black-Right-Pointing-Pointer Apoptosis by Cd in the frog testes is related to Caspase-3, Bax and Bcl-2 genes. - Abstract: This study explored the genetic damage induced by cadmium exposure in the testes of Rana limnocharis. Healthy adult frogs were exposed to 2.5, 5, 7.5, or 10 mg/L of cadmium solution for 14 days. The results showed that exposure to these concentrations increased the levels of reactive oxygen species and malondialdehyde content in the testes, clearly indicating a dose-effect relationship. Moreover, the same dosages of Cd{sup 2+} solution increased glutathione (reduced) content, with the values being significantly different from those observed in the control group (P < 0.01). The comet assay results demonstrated that the DNA damage rate, tail length, and tail moment of samples obtained from frogs exposed to 2.5-7.5 mg/L of cadmium solution significantly increased compared with those of samples obtained from the control group (P < 0.01). These findings suggest that cadmium can induce free radical generation, followed by lipid peroxidation and DNA damage. Ultrastructural observation revealed vacuoles in the spermatogenic cells, cell dispersion, incomplete cell structures, and deformed nucleoli. Moreover, cadmium exposure induced significant down-regulation of Bcl-2 expression and up-regulation of Bax and caspase-3 expressions. Taken together, these data indicate that cadmium can induce testicular cell apoptosis in R. limnocharis. Exploring the effects of cadmium on the mechanism of reproductive toxicity in amphibians will help provide a

Cadmium-induced oxidative stress and apoptosis in the testes of frog Rana limnocharis

International Nuclear Information System (INIS)

Zhang Hangjun; Cai Chenchen; Shi Cailei; Cao Hui; Han Ziliu; Jia Xiuying

2012-01-01

Highlights: ► Cd can cause vacuoles and deformity of the spermatogenic cells in the frog testes. ► Cd can result in oxidative stress in the frog testes. ► Cd can induce significantly increase of ROS contents triggered DNA damages in the frog testes. ► Cd can cause apoptosis in the testes of male R. limnocharis. ► Apoptosis by Cd in the frog testes is related to Caspase-3, Bax and Bcl-2 genes. - Abstract: This study explored the genetic damage induced by cadmium exposure in the testes of Rana limnocharis. Healthy adult frogs were exposed to 2.5, 5, 7.5, or 10 mg/L of cadmium solution for 14 days. The results showed that exposure to these concentrations increased the levels of reactive oxygen species and malondialdehyde content in the testes, clearly indicating a dose–effect relationship. Moreover, the same dosages of Cd 2+ solution increased glutathione (reduced) content, with the values being significantly different from those observed in the control group (P < 0.01). The comet assay results demonstrated that the DNA damage rate, tail length, and tail moment of samples obtained from frogs exposed to 2.5–7.5 mg/L of cadmium solution significantly increased compared with those of samples obtained from the control group (P < 0.01). These findings suggest that cadmium can induce free radical generation, followed by lipid peroxidation and DNA damage. Ultrastructural observation revealed vacuoles in the spermatogenic cells, cell dispersion, incomplete cell structures, and deformed nucleoli. Moreover, cadmium exposure induced significant down-regulation of Bcl-2 expression and up-regulation of Bax and caspase-3 expressions. Taken together, these data indicate that cadmium can induce testicular cell apoptosis in R. limnocharis. Exploring the effects of cadmium on the mechanism of reproductive toxicity in amphibians will help provide a scientific basis accounting for the global population decline in amphibian species.

Oral chytridiomycosis in the mountain yellow-legged frog (Rana muscosa)

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Fellers, G.M.; Green, E.D.; Longcore, J.E.

2001-01-01

The chytrid fungus Batrachochytrium dendrobatidis was originally reported in wild frog populations in Panama and Australia, and from captive frogs in the U.S. National Zoological Park (Washington, DC). This recently described fungus affects the keratinized epidermis of amphibians and has been implicated as a causative factor in the declines of frog populations. We report here the presence of B. dendrobatidis in larval and recently metamorphosed mountain yellow-legged frogs (Rana muscosa) in or near the Sierra Nevada Mountains of California, an area where declines have been documented in all five species of native anurans. Forty-one percent (158 of 387) of larval R. muscosa examined in the field with a hand lens and 18% (14 of 79) of preserved larvae had abnormalities of the oral disc. Twenty-eight larvae were collected from 10 sites where tadpoles had been observed with missing or abnormally keratinized mouthparts, and 24 of these were examined for infection. Sixty-seven percent (16 of 24) of these tadpoles were infected with B. dendrobatidis. Batrachochytrium dendrobatidis was cultured from both tadpoles and recent metamorphs from one of these sites. Tadpoles with mouthpart abnormalities or confirmed chytrid fungus infections were collected at 23 sites spanning a distance of > 440 km and an elevational range from 1658-3550 m. Life-history traits of R. muscosa may make this species particularly susceptible to infection by Batrachochytrium. We recommend that biologists examine tadpoles for oral disc abnormalities as a preliminary indication of chytridiomycosis. Further, we believe that biologists should take precautions to prevent spreading this and other amphibian diseases from one site to another.

Xenopus laevis Retinal Ganglion Cell Dendritic Arbors Develop Independently of Visual Stimulation

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Barbara Lom

2004-01-01

Full Text Available Newly formed neurons must locate their appropriate target cells and then form synaptic connections with these targets in order to establish a functional nervous system. In the vertebrate retina, retinal ganglion cell (RGC dendrites extend from the cell body and form synapses with nearby amacrine and bipolar cells. RGC axons, however, exit the retina and synapse with the dendrites of midbrain neurons in the optic tectum. We examined how visual stimulation influenced Xenopus RGC dendritic arborization. Neuronal activity is known to be an important factor in shaping dendritic and axonal arborization. Thus, we reared tadpoles in dark and light environments then used rhodamine dextran retrograde labeling to identify RGCs in the retina. When we compared RGC dendritic arbors from tadpoles reared in dark and light environments, we found no morphological differences, suggesting that physiological visual activity did not contribute to the morphological development of Xenopus RGC dendritic arbors.

Reflex Marine celebrates 10. anniversary of FROG crew transfer device

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Anon.

2010-07-15

Reflex Marine developed the initial 3-person FROG crew transfer device in response to the main risks identified from incidents involving traditional rope baskets for personnel transfer: falling, collisions, hard landings, and immersion. To address these issues, the FROG was developed with 4-point harnesses, a protective shell, shock-absorbing landing feet, and self-righting capability. As a result of industry demand for a higher capacity transfer device, the company introduced 6- and 9-man versions of the FROG. The perceptions and reality of marine transfers have changed greatly over the past decade, from the design of the device to vessel specifications and increased focus on crane operations. Marine transfers offer a low-risk alternative to helicopter transfers. The TORO, a low-cost crew transfer capsule launched in February 2009, fits into a standard shipping container, providing significant logistical advantages. The TORO can carry 4 passengers, offer protection from side impacts and hard landings, and is buoyant and self-righting. Most of the units are being used by major oil and gas companies, but offshore wind turbines are an emerging source of demand for the crew transfer system. 3 figs.

Cytological maps of lampbrush chromosomes of European water frogs (Pelophylax esculentus complex) from the Eastern Ukraine

Science.gov (United States)

2013-01-01

Background Hybridogenesis (hemiclonal inheritance) is a kind of clonal reproduction in which hybrids between parental species are reproduced by crossing with one of the parental species. European water frogs (Pelophylax esculentus complex) represent an appropriate model for studying interspecies hybridization, processes of hemiclonal inheritance and polyploidization. P. esculentus complex consists of two parental species, P. ridibundus (the lake frog) and P. lessonae (the pool frog), and their hybridogenetic hybrid – P. esculentus (the edible frog). Parental and hybrid frogs can reproduce syntopically and form hemiclonal population systems. For studying mechanisms underlying the maintenance of water frog population systems it is required to characterize the karyotypes transmitted in gametes of parental and different hybrid animals of both sexes. Results In order to obtain an instrument for characterization of oocyte karyotypes in hybrid female frogs, we constructed cytological maps of lampbrush chromosomes from oocytes of both parental species originating in Eastern Ukraine. We further identified certain molecular components of chromosomal marker structures and mapped coilin-rich spheres and granules, chromosome associated nucleoli and special loops accumulating splicing factors. We recorded the dissimilarities between P. ridibundus and P. lessonae lampbrush chromosomes in the length of orthologous chromosomes, number and location of marker structures and interstitial (TTAGGG)n-repeat sites as well as activity of nucleolus organizer. Satellite repeat RrS1 was mapped in centromere regions of lampbrush chromosomes of the both species. Additionally, we discovered transcripts of RrS1 repeat in oocytes of P. ridibundus and P. lessonae. Moreover, G-rich transcripts of telomere repeat were revealed in association with terminal regions of P. ridibundus and P. lessonae lampbrush chromosomes. Conclusions The constructed cytological maps of lampbrush chromosomes of P

Effects of oxymorphazone in frogs: long lasting antinociception in vivo, and apparently irreversible binding in vitro

Energy Technology Data Exchange (ETDEWEB)

Benyhe, S.; Hoffman, G.; Varga, E.; Hosztafi, S.; Toth, G.; Borsodi, A.; Wollemann, M.

1989-01-01

Oxymorphazone was found to be a relatively weak antinociceptive drug in intact frog (Rana esculenta) when acetic acid was used as pain stimulus. Frogs remained analgesic for at least 48 hrs following oxymorphazone administration. The ligand increased the latency of wiping reflex in spinal frogs too. There effects were blocked by naloxone. In equilibrium binding studies (/sup 3/H)oxymorphazone had high affinity to the opioid receptors of frog brain and spinal cord as well. Kinetic experiments show that only 25% of the bound (/sup 3/H)oxymorphazone is readily dissociable. Preincubation of the membranes with labeled oxymorphazone results in a washing resistant inhibition of the opioid binding sites. At least 70% of the (/sup 3/H)oxymorphazone specific binding is apparently irreversible after reaction at 5 nM ligand concentration, and this can be enhanced by a higher concentration of tritiated ligand.

Vision drives correlated activity without patterned spontaneous activity in developing Xenopus retina.

Science.gov (United States)

Demas, James A; Payne, Hannah; Cline, Hollis T

2012-04-01

Developing amphibians need vision to avoid predators and locate food before visual system circuits fully mature. Xenopus tadpoles can respond to visual stimuli as soon as retinal ganglion cells (RGCs) innervate the brain, however, in mammals, chicks and turtles, RGCs reach their central targets many days, or even weeks, before their retinas are capable of vision. In the absence of vision, activity-dependent refinement in these amniote species is mediated by waves of spontaneous activity that periodically spread across the retina, correlating the firing of action potentials in neighboring RGCs. Theory suggests that retinorecipient neurons in the brain use patterned RGC activity to sharpen the retinotopy first established by genetic cues. We find that in both wild type and albino Xenopus tadpoles, RGCs are spontaneously active at all stages of tadpole development studied, but their population activity never coalesces into waves. Even at the earliest stages recorded, visual stimulation dominates over spontaneous activity and can generate patterns of RGC activity similar to the locally correlated spontaneous activity observed in amniotes. In addition, we show that blocking AMPA and NMDA type glutamate receptors significantly decreases spontaneous activity in young Xenopus retina, but that blocking GABA(A) receptor blockers does not. Our findings indicate that vision drives correlated activity required for topographic map formation. They further suggest that developing retinal circuits in the two major subdivisions of tetrapods, amphibians and amniotes, evolved different strategies to supply appropriately patterned RGC activity to drive visual circuit refinement. Copyright © 2011 Wiley Periodicals, Inc.

Migratory and adhesive properties of Xenopus laevis primordial germ cells in vitro

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Aliaksandr Dzementsei

2013-11-01

The directional migration of primordial germ cells (PGCs to the site of gonad formation is an advantageous model system to study cell motility. The embryonic development of PGCs has been investigated in different animal species, including mice, zebrafish, Xenopus and Drosophila. In this study we focus on the physical properties of Xenopus laevis PGCs during their transition from the passive to the active migratory state. Pre-migratory PGCs from Xenopus laevis embryos at developmental stages 17–19 to be compared with migratory PGCs from stages 28–30 were isolated and characterized in respect to motility and adhesive properties. Using single-cell force spectroscopy, we observed a decline in adhesiveness of PGCs upon reaching the migratory state, as defined by decreased attachment to extracellular matrix components like fibronectin, and a reduced adhesion to somatic endodermal cells. Data obtained from qPCR analysis with isolated PGCs reveal that down-regulation of E-cadherin might contribute to this weakening of cell-cell adhesion. Interestingly, however, using an in vitro migration assay, we found that movement of X. laevis PGCs can also occur independently of specific interactions with their neighboring cells. The reduction of cellular adhesion during PGC development is accompanied by enhanced cellular motility, as reflected in increased formation of bleb-like protrusions and inferred from electric cell-substrate impedance sensing (ECIS as well as time-lapse image analysis. Temporal alterations in cell shape, including contraction and expansion of the cellular body, reveal a higher degree of cellular dynamics for the migratory PGCs in vitro.

Subcellular localization of class I histone deacetylases in the developing Xenopus tectum

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Xia eGuo

2016-01-01

Full Text Available Histone deacetylases (HDACs are thought to localize in the nucleus to regulate gene transcription and play pivotal roles in neurogenesis, apoptosis and plasticity. However, the subcellular distribution of class I HDACs in the developing brain remains unclear. Here, we show that HDAC1 and HDAC2 are located in both the mitochondria and the nucleus in the Xenopus laevis stage 34 tectum and are mainly restricted to the nucleus following further brain development. HDAC3 is widely present in the mitochondria, nucleus and cytoplasm during early tectal development and is mainly distributed in the nucleus in stage 45 tectum. In contrast, HDAC8 is broadly located in the mitochondria, nucleus and cytoplasm during tectal development. These data demonstrate that HDAC1, HDAC2 and HDAC3 are transiently localized in the mitochondria and that the subcellular distribution of class I HDACs in the Xenopus tectum is heterogeneous. Furthermore, we observed that spherical mitochondria accumulate in the cytoplasm at earlier stages, whereas elongated mitochondria are evenly distributed in the tectum at later stages. The activity of histone acetylation (H4K12 remains low in mitochondria during tectal development. Pharmacological blockades of HDACs using a broad spectrum HDAC inhibitor of Trichostatin A (TSA or specific class I HDAC inhibitors of MS-275 and MGCD0103 decrease the number of mitochondria in the tectum at stage 34. These findings highlight a link between the subcellular distribution of class I HDACs and mitochondrial dynamics in the developing optic tectum of Xenopus laevis.

Effect of cattle exclosures on Columbia Spotted Frog abundance

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Adams, Michael J.; Pearl, Christopher; Chambert, Thierry; Mccreary, Brome; Galvan, Stephanie; Rowe, Jennifer

2018-01-01

Livestock grazing is an important land use in the western USA and can have positive or negative effects on amphibians. Columbia Spotted Frog (Rana luteiventris) often use ponds that provide water for cattle. We conducted a long-term manipulative study on US Forest Service land in northeastern Oregon to determine the effects of full and partial exclosures that limited cattle access to ponds used by frogs. We found weak evidence of a short-term increase in abundance that did not differ between full and partial exclosures and that diminished with continuing exclusion of cattle. The benefit of exclosures was small relative to the overall decline in breeding numbers that we documented. This suggests that some protection can provide a short-term boost to populations.

Hind limb malformations in free-living northern leopard frogs (Rana pipiens) from Maine, Minnesota, and Vermont suggest multiple etiologies

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Meteyer, C.U.; Loeffler, I.K.; Fallon, J.F.; Converse, K.A.; Green, E.; Helgen, J.C.; Kersten, S.; Levey, R.; Eaton-Poole, L.; Burkhart, J.G.

2000-01-01

Background Reports of malformed frogs have increased throughout the North American continent in recent years. Most of the observed malformations have involved the hind limbs. The goal of this study was to accurately characterize the hind limb malformations in wild frogs as an important step toward understanding the possible etiologies. Methods During 1997 and 1998, 182 recently metamorphosed northern leopard frogs (Rana pipiens) were collected from Minnesota, Vermont, and Maine. Malformed hind limbs were present in 157 (86%) of these frogs, which underwent necropsy and radiographic evaluation at the National Wildlife Health Center. These malformations are described in detail and classified into four major categories: (1) no limb (amelia); (2) multiple limbs or limb elements (polymelia, polydactyly, polyphalangy); (3) reduced limb segments or elements (phocomelia, ectromelia, ectrodactyly, and brachydactyly; and (4) distally complete but malformed limb (bone rotations, bridging, skin webbing, and micromelia). Results Amelia and reduced segments and/or elements were the most common finding. Frogs with bilateral hind limb malformations were not common, and in only eight of these 22 frogs were the malformations symmetrical. Malformations of a given type tended to occur in frogs collected from the same site, but the types of malformations varied widely among all three states, and between study sites within Minnesota. Conclusions Clustering of malformation type suggests that developmental events may produce a variety of phenotypes depending on the timing, sequence, and severity of the environmental insult. Hind limb malformations in free-living frogs transcend current mechanistic explanations of tetrapod limb development.

Metabolomic profiling of Green Frogs exposed to Mixed Pesticides

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U.S. Environmental Protection Agency — GC/MS data from the metabolomic profiling of green frog livers after exposure to pesticides and their mixtures. This dataset is associated with the following...

Thermal ecological physiology of native and invasive frog species: do invaders perform better?

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Cortes, Pablo A; Puschel, Hans; Acuña, Paz; Bartheld, José L; Bozinovic, Francisco

2016-01-01

Biological invasions are recognized as an important biotic component of global change that threatens the composition, structure and functioning of ecosystems, resulting in loss of biodiversity and displacement of native species. Although ecological characteristics facilitating the establishment and spread of non-native species are widely recognized, little is known about organismal attributes underlying invasion success. In this study, we tested the effect of thermal acclimation on thermal tolerance and locomotor performance in the invasive Xenopus laevis and the Chilean native Calyptocephalella gayi . In particular, the maximal righting performance (μ MAX ), optimal temperature ( T O ), lower (CT min ) and upper critical thermal limits (CT max ), thermal breadth ( T br ) and the area under the performance curve (AUC) were studied after 6 weeks acclimation to 10 and 20°C. We observed higher values of μ max and AUC in X. laevis in comparison to C. gayi . On the contrary, the invasive species showed lower values of CT min in comparison to the native one. In contrast, CT max , T O and T br showed no inter-specific differences. Moreover, we found that both species have the ability to acclimate their locomotor performance and lower thermal tolerance limit at low temperatures. Our results demonstrate that X. laevis is a better performer than C. gayi . Although there were differences in CT min , the invasive and native frogs did not differ in their thermal tolerance. Interestingly, in both species the lower and upper critical thermal limits are beyond the minimal and maximal temperatures encountered in nature during the coldest and hottest month, respectively. Overall, our findings suggest that both X. laevis and C. gayi would be resilient to climate warming expectations in Chile.

Regulation of 5'-adenosine monophosphate deaminase in the freeze tolerant wood frog, Rana sylvatica.

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Dieni, Christopher A; Storey, Kenneth B

2008-04-22

The wood frog, Rana sylvatica, is one of a few vertebrate species that have developed natural freeze tolerance, surviving days or weeks with 65-70% of its total body water frozen in extracellular ice masses. Frozen frogs exhibit no vital signs and their organs must endure multiple stresses, particularly long term anoxia and ischemia. Maintenance of cellular energy supply is critical to viability in the frozen state and in skeletal muscle, AMP deaminase (AMPD) plays a key role in stabilizing cellular energetics. The present study investigated AMPD control in wood frog muscle. Wood frog AMPD was subject to multiple regulatory controls: binding to subcellular structures, protein phosphorylation, and effects of allosteric effectors, cryoprotectants and temperature. The percentage of bound AMPD activity increased from 20 to 35% with the transition to the frozen state. Bound AMPD showed altered kinetic parameters compared with the free enzyme (S0.5 AMP was reduced, Hill coefficient fell to approximately 1.0) and the transition to the frozen state led to a 3-fold increase in S0.5 AMP of the bound enzyme. AMPD was a target of protein phosphorylation. Bound AMPD from control frogs proved to be a low phosphate form with a low S0.5 AMP and was phosphorylated in incubations that stimulated PKA, PKC, CaMK, or AMPK. Bound AMPD from frozen frogs was a high phosphate form with a high S0.5 AMP that was reduced under incubation conditions that stimulated protein phosphatases. Frog muscle AMPD was activated by Mg.ATP and Mg.ADP and inhibited by Mg.GTP, KCl, NaCl and NH4Cl. The enzyme product, IMP, uniquely inhibited only the bound (phosphorylated) enzyme from muscle of frozen frogs. Activators and inhibitors differentially affected the free versus bound enzyme. S0.5 AMP of bound AMPD was also differentially affected by high versus low assay temperature (25 vs 5 degrees C) and by the presence/absence of the natural cryoprotectant (250 mM glucose) that accumulates during freezing

Characterization of kappa 1 and kappa 2 opioid binding sites in frog (Rana esculenta) brain membrane preparation

Energy Technology Data Exchange (ETDEWEB)

Benyhe, S.; Varga, E.; Hepp, J.; Magyar, A.; Borsodi, A.; Wollemann, M.

1990-09-01

The distribution and properties of frog brain kappa-opioid receptor subtypes differ not only from those of the guinea pig brain, but also from that of the rat brain. In guinea pig cerebellum the kappa 1 is the dominant receptor subtype, frog brain contains mainly the kappa 2 subtype, and the distribution of the rat brain subtypes is intermediate between the two others. In competition experiments it has been established that ethylketocyclazocine and N-cyclopropylmethyl-norazidomorphine, which are nonselective kappa-ligands, have relatively high affinities to frog brain membranes. The kappa 2 ligands (Met5)enkephalin-Arg6-Phe7 and etorphine also show high affinities to the frog brain. Kappa 1 binding sites measured in the presence of 5 microM/D-Ala2-Leu5/enkephalin represent 25-30% of (3H)ethylketocyclazocine binding in frog brain membranes. The kappa 2 subtype in frog brain resembles more to the mu subtype than the delta subtype of opioid receptors, but it differs from the mu subtype in displaying low affinity toward beta-endorphin and /D-Ala2-(Me)Phe4-Gly5-ol/enkephalin (DAGO). From our data it is evident that the opioid receptor subtypes are already present in the amphibian brain but the differences among them are less pronounced than in mammalian brain.

Characterization of kappa 1 and kappa 2 opioid binding sites in frog (Rana esculenta) brain membrane preparation

International Nuclear Information System (INIS)

Benyhe, S.; Varga, E.; Hepp, J.; Magyar, A.; Borsodi, A.; Wollemann, M.

1990-01-01

The distribution and properties of frog brain kappa-opioid receptor subtypes differ not only from those of the guinea pig brain, but also from that of the rat brain. In guinea pig cerebellum the kappa 1 is the dominant receptor subtype, frog brain contains mainly the kappa 2 subtype, and the distribution of the rat brain subtypes is intermediate between the two others. In competition experiments it has been established that ethylketocyclazocine and N-cyclopropylmethyl-norazidomorphine, which are nonselective kappa-ligands, have relatively high affinities to frog brain membranes. The kappa 2 ligands (Met5)enkephalin-Arg6-Phe7 and etorphine also show high affinities to the frog brain. Kappa 1 binding sites measured in the presence of 5 microM/D-Ala2-Leu5/enkephalin represent 25-30% of [3H]ethylketocyclazocine binding in frog brain membranes. The kappa 2 subtype in frog brain resembles more to the mu subtype than the delta subtype of opioid receptors, but it differs from the mu subtype in displaying low affinity toward beta-endorphin and /D-Ala2-(Me)Phe4-Gly5-ol/enkephalin (DAGO). From our data it is evident that the opioid receptor subtypes are already present in the amphibian brain but the differences among them are less pronounced than in mammalian brain

Medicinal use of secretions (“the frog vaccine” from the kambô frog (Phyllomedusa bicolor by non-indigenous peoples in Rondônia, Brazil

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Paulo Sérgio Bernarde

2009-09-01

Full Text Available Amphibians have pharmaceutically active skin secretions that protect against infections and predation. Some indigenous people in southwestern Amazonia use these secretions from P. bicolor for medicinal purposes. While the use of these secretions by indigenous people is relatively well-known, the use by non-indigenous peoples is very poorly studied. Here we describe the use of the “frog vaccine” by non-indigenous populations in the Brazilian state of Rondônia. Thirty-one people who had received this “vaccine” were interviewed. The use of this vaccine is not typical or habitual in this region, and the person who administers the vaccine must travel from another part of Amazonia. Users of the vaccine come from middle and upper social classes with reasonable levels of education (primary, secondary and university. Approximately half the people vaccinated felt that their health had improved after vaccination and if need be, they would take the vaccination again. Most of the people do not know the frog species from which the secretions are taken. While the people who use this treatment believe that it is good for any infirmity, the medicinal properties, if any, of the “frog vaccine” are under study and are still unknown.

Membrane junctions in Xenopus eggs: their distribution suggests a role in calcium regulation.

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Gardiner, D M; Grey, R D

1983-04-01

We have observed the presence of membrane junctions formed between the plasma membrane and cortical endoplasmic reticulum of mature, unactivated eggs of xenopus laevis. The parallel, paired membranes of the junction are separated by a 10-mn gap within which electron-dense material is present. This material occurs in patches with an average center-to-center distance of approximately 30 nm. These junctions are rare in immature (but fully grown) oocytes (approximately 2 percent of the plasma membrane is associated with junctions) and increase dramatically during progesterone-induced maturation. Junctions in the mature, unactivated egg are two to three times more abundant in the animal hemisphere (25-30 percent of the plasma membrane associated with junction) as compared with the vegetal hemisphere (10-15 percent). Junction density decreases rapidly to values characteristic of immature oocytes in response to egg activation. The plasma membrane-ER junctions of xenopus eggs are strikingly similar in structure to membrane junctions in muscle cells thought to be essential in the triggering of intracellular calcium release from the sarcoplasmic reticulum. In addition, the junctions' distinctive, animal-vegetal polarity of distribution, their dramatic appearance during maturation, and their disapperance during activation are correlated with previously documented patterns of calcium-mediated events in anuran eggs. We discuss several lines of evidence supporting the hypothesis that these junctions in xenopus eggs are sites that transduce extracellular events into intracellular calcium release during fertilization and activation of development.

Surveys for California red-legged frog and arroyo toad on the Los Padres National Forest

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Valerie K. Hubbartt; Thomas G. Murphey

2005-01-01

Starting in the spring of 1999 through the fall of 2000, USDA Forest Service biologists have conducted surveys throughout the Los Padres National Forest for the federally-listed California red-legged frog (Rana aurora draytonii) and arroyo toad (Bufo californicus). Sites known to have frogs or toads present were monitored for...

DNA is a co-factor for its own replication in Xenopus egg extracts

NARCIS (Netherlands)

Lebofsky, Ronald; van Oijen, Antoine M.; Walter, Johannes C.

Soluble Xenopus egg extracts efficiently replicate added plasmids using a physiological mechanism, and thus represent a powerful system to understand vertebrate DNA replication. Surprisingly, DNA replication in this system is highly sensitive to plasmid concentration, being undetectable below

Notochord-derived hedgehog is essential for tail regeneration in Xenopus tadpole.

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Taniguchi, Yuka; Watanabe, Kenji; Mochii, Makoto

2014-06-18

Appendage regeneration in amphibians is regulated by the combinatorial actions of signaling molecules. The requirement of molecules secreted from specific tissues is reflected by the observation that the whole process of regeneration can be inhibited if a certain tissue is removed from the amputated stump. Interestingly, urodeles and anurans show different tissue dependencies during tail regeneration. The spinal cord is essential for tail regeneration in urodele but not in anuran larva, whereas the notochord but not the spinal cord is essential for tail regeneration in anuran tadpoles. Sonic hedgehog is one of the signaling molecules responsible for such phenomenon in axolotl, as hedgehog signaling is essential for overall tail regeneration and sonic hedgehog is exclusively expressed in the spinal cord. In order to know whether hedgehog signaling is involved in the molecular mechanism underlying the inconsistent tissue dependency for tail regeneration between anurans and urodeles, we investigated expression of hedgehog signal-related genes in the regenerating tail of Xenopus tadpole and examined the effect of the hedgehog signal inhibitor, cyclopamine, on the tail regeneration. In Xenopus, sonic hedgehog is expressed exclusively in the notochord but not in the spinal cord of the regenerate. Overall regeneration was severely impaired in cyclopamine-treated tadpoles. Notochord maturation in the regenerate, including cell alignment and vacuolation, and myofiber formation were inhibited. Proliferation of spinal cord cells in the neural ampulla and of mesenchymal cells was also impaired. As in the axolotl, hedgehog signaling is required for multiple steps in tail regeneration in the Xenopus tadpole, although the location of the Shh source is quite different between the two species. This difference in Shh localization is the likely basis for the differing tissue requirement for tail regeneration between urodeles and anurans.

Growth-arrest-specific protein 2 inhibits cell division in Xenopus embryos.

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Tong Zhang

Full Text Available Growth-arrest-specific 2 gene was originally identified in murine fibroblasts under growth arrest conditions. Furthermore, serum stimulation of quiescent, non-dividing cells leads to the down-regulation of gas2 and results in re-entry into the cell cycle. Cytoskeleton rearrangements are critical for cell cycle progression and cell division and the Gas2 protein has been shown to co-localize with actin and microtubules in interphase mammalian cells. Despite these findings, direct evidence supporting a role for Gas2 in the mechanism of cell division has not been reported.To determine whether the Gas2 protein plays a role in cell division, we over-expressed the full-length Gas2 protein and Gas2 truncations containing either the actin-binding CH domain or the tubulin-binding Gas2 domain in Xenopus laevis embryos. We found that both the full-length Gas2 protein and the Gas2 domain, but not the CH domain, inhibited cell division and resulted in multinucleated cells. The observation that Gas2 domain alone can arrest cell division suggests that Gas2 function is mediated by microtubule binding. Gas2 co-localized with microtubules at the cell cortex of Gas2-injected Xenopus embryos using cryo-confocal microscopy and co-sedimented with microtubules in cytoskeleton co-sedimentation assays. To investigate the mechanism of Gas2-induced cell division arrest, we showed, using a wound-induced contractile array assay, that Gas2 stabilized microtubules. Finally, electron microscopy studies demonstrated that Gas2 bundled microtubules into higher-order structures.Our experiments show that Gas2 inhibits cell division in Xenopus embryos. We propose that Gas2 function is mediated by binding and bundling microtubules, leading to cell division arrest.

A comparative study of charge movement in rat and frog skeletal muscle fibres.

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Hollingworth, S; Marshall, M W

1981-12-01

1. The middle of the fibre voltage--clamp technique (Adrian & Marshall, 1977), modified where necessary for electrically short muscle fibres, has been used to measure non-linear charge movements in mammalian fast twitch (rat extensor digitorum longus), mammalian slow twitch (rat soleus) and frog (sartorius) muscles. 2. The maximum amount of charge moved in mammalian fast twitch muscle at 2 degrees C in hypertonic solution, was 3--5 times greater than in slow twitch muscle. The voltage distribution of fast twitch charge was 10--15 mV more positive when compared to slow twitch. 3. In both mammalian muscle types hypertonic Ringer solution negatively shifted the voltage distribution of charge some 6 mV. The steepness of charge moved around mechanical threshold was unaffected by hypertonicity. 4. The amount of charge in frog sartorius fibres at 2 degrees C in hypertonic solution was about half of that in rat fast twitch muscle; the voltage distribution of the frog charge was similar to rat soleus muscle. 5. Warming between 2 and 15 degrees C had no effect on either the amount of steady-state distribution of charge in mammalian or frog muscles. 6. At 2 degrees C, the kinetics of charge movement in fast and slow twitch mammalian muscles were similar and 2--3 times faster than frog muscle at the same temperature. In fast and slow mammalian fibres at 2 degrees C similar times were taken to shift the same fractions of the total amount of charge. The Q10 of charge movement kinetics was between 1.2 and 2.0 in the three muscles studied.

Electrophysiological evidence for an ATP-gated ion channel in the principal cells of the frog skin epithelium

DEFF Research Database (Denmark)

Brodin, Birger; Nielsen, Robert

2000-01-01

P2X receptor, Na+ absorption, Short circuit current, Cell potential, Microelectrodes, Frog skin, Cytosolic Ca2+......P2X receptor, Na+ absorption, Short circuit current, Cell potential, Microelectrodes, Frog skin, Cytosolic Ca2+...

Pesticides and Population Declines of California Alpine Frogs

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Airborne pesticides from the Central Valley of California have been implicated as a cause for population declines of several amphibian species, with the strongest evidence for the mountain yellow-legged frog complex (Rana muscosa and R. sierrae) in the Sierra Nevada. We measured ...

Short-term occupancy and abundance dynamics of the Oregon spotted frog (Rana pretiosa) across its core range

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Adams, Michael J.; Pearl, Christopher A.; Mccreary, Brome; Galvan, Stephanie

2014-01-01

The Oregon spotted frog (Rana pretiosa) occupies only a fraction of its original range and is listed as Threatened under the Endangered Species Act. We surveyed 93 sites in a rotating frame design (2010–13) in the Klamath and Deschutes Basins, Oregon, which encompass most of the species’ core extant range. Oregon spotted frogs are declining in abundance and probability of site occupancy. We did not find an association between the probability that Oregon spotted frogs disappear from a site (local extinction) and any of the variables hypothesized to affect Oregon spotted frog occupancy. This 4-year study provides baseline data, but the 4-year period was too short to draw firm conclusions. Further study is essential to understand how habitat changes and management practices relate to the status and trends of this species.

Consistent left-right asymmetry cannot be established by late organizers in Xenopus unless the late organizer is a conjoined twin.

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Vandenberg, Laura N; Levin, Michael

2010-04-01

How embryos consistently orient asymmetries of the left-right (LR) axis is an intriguing question, as no macroscopic environmental cues reliably distinguish left from right. Especially unclear are the events coordinating LR patterning with the establishment of the dorsoventral (DV) axes and midline determination in early embryos. In frog embryos, consistent physiological and molecular asymmetries manifest by the second cell cleavage; however, models based on extracellular fluid flow at the node predict correct de novo asymmetry orientation during neurulation. We addressed these issues in Xenopus embryos by manipulating the timing and location of dorsal organizer induction: the primary dorsal organizer was ablated by UV irradiation, and a new organizer was induced at various locations, either early, by mechanical rotation, or late, by injection of lithium chloride (at 32 cells) or of the transcription factor XSiamois (which functions after mid-blastula transition). These embryos were then analyzed for the position of three asymmetric organs. Whereas organizers rescued before cleavage properly oriented the LR axis 90% of the time, organizers induced in any position at any time after the 32-cell stage exhibited randomized laterality. Late organizers were unable to correctly orient the LR axis even when placed back in their endogenous location. Strikingly, conjoined twins produced by late induction of ectopic organizers did have normal asymmetry. These data reveal that although correct LR orientation must occur no later than early cleavage stages in singleton embryos, a novel instructive influence from an early organizer can impose normal asymmetry upon late organizers in the same cell field.

Lithobates sylvaticus (wood frog)

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Fuller, Pam

2016-01-01

A single specimen found southwest of Hattiesburg in Timberton (31.270391oN, 89.327675oW; WGS 84). 23 July 2015. Gary, Kat, and Ron Lukens. Verifi ed by Kenneth Krysko, Florida Museum of Natural History (UF-Herpetology 176455). This species has never been recorded from the state of Mississippi before (Dodd 2013. Frogs of the United States and Canada – Volume 2. John Hopkins University Press, Baltimore, Maryland. 982 pp.). According to Dodd (2013), the closest population is located in east central Alabama, approximately 400 km to the northeast, as documented by Davis and Folkerts (1986. Brimleyana 12:29-50).

Enzymatic regulation of seasonal glycogen cycling in the freeze-tolerant wood frog, Rana sylvatica.

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do Amaral, M Clara F; Lee, Richard E; Costanzo, Jon P

2016-12-01

Liver glycogen is an important energy store in vertebrates, and in the freeze-tolerant wood frog, Rana sylvatica, this carbohydrate also serves as a major source of the cryoprotectant glucose. We investigated how variation in the levels of the catalytic subunit of protein kinase A (PKAc), glycogen phosphorylase (GP), and glycogen synthase (GS) relates to seasonal glycogen cycling in a temperate (Ohioan) and subarctic (Alaskan) populations of this species. In spring, Ohioan frogs had reduced potential for glycogen synthesis, as evidenced by low GS activity and high PKAc protein levels. In addition, glycogen levels in spring were the lowest of four seasonal samples, as energy input was likely directed towards metabolism and somatic growth during this period. Near-maximal glycogen levels were reached by mid-summer, and remained unchanged in fall and winter, suggesting that glycogenesis was curtailed during this period. Ohioan frogs had a high potential for glycogenolysis and glycogenesis in winter, as evidenced by large glycogen reserves, high levels of GP and GS proteins, and high GS activity, which likely allows for rapid mobilization of cryoprotectant during freezing and replenishing of glycogen reserves during thawing. Alaskan frogs also achieved a near-maximal liver glycogen concentration by summer and displayed high glycogenic and glycogenolytic potential in winter, but, unlike Ohioan frogs, started replenishing their energy reserves early in spring. We conclude that variation in levels of both glycogenolytic and glycogenic enzymes likely happens in response to seasonal changes in energetic strategies and demands, with winter survival being a key component to understanding the regulation of glycogen cycling in this species.

Internal pigment cells respond to external UV radiation in frogs.

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Franco-Belussi, Lilian; Nilsson Sköld, Helen; de Oliveira, Classius

2016-05-01

Fish and amphibians have pigment cells that generate colorful skins important for signaling, camouflage, thermoregulation and protection against ultraviolet radiation (UVR). However, many animals also have pigment cells inside their bodies, on their internal organs and membranes. In contrast to external pigmentation, internal pigmentation is remarkably little studied and its function is not well known. Here, we tested genotoxic effects of UVR and its effects on internal pigmentation in a neotropical frog, Physalaemus nattereri We found increases in body darkness and internal melanin pigmentation in testes and heart surfaces and in the mesenterium and lumbar region after just a few hours of UVR exposure. The melanin dispersion in melanomacrophages in the liver and melanocytes in testes increased after UV exposure. In addition, the amount of melanin inside melanomacrophages cells also increased. Although mast cells were quickly activated by UVR, only longer UVR exposure resulted in genotoxic effects inside frogs, by increasing the frequency of micronuclei in red blood cells. This is the first study to describe systemic responses of external UVR on internal melanin pigmentation, melanomacrophages and melanocytes in frogs and thus provides a functional explanation to the presence of internal pigmentation. © 2016. Published by The Company of Biologists Ltd.

Mechanisms underlying the noradrenergic modulation of longitudinal coordination during swimming in Xenopus laevis tadpoles

DEFF Research Database (Denmark)

Merrywest, Simon D; McDearmid, Jonathan R; Kjaerulff, Ole

2003-01-01

Noradrenaline (NA) is a potent modulator of locomotion in many vertebrate nervous systems. When Xenopus tadpoles swim, waves of motor neuron activity alternate across the body and propagate along it with a brief rostro-caudal delay (RC-delay) between segments. We have now investigated the mechani......Noradrenaline (NA) is a potent modulator of locomotion in many vertebrate nervous systems. When Xenopus tadpoles swim, waves of motor neuron activity alternate across the body and propagate along it with a brief rostro-caudal delay (RC-delay) between segments. We have now investigated...... might promote postinhibitory rebound firing. The synaptic inputs during swimming were simulated using a sustained positive current, superimposed upon which were brief negative currents. When these conditions were held constant NA enhanced the probability of rebound firing--indicating a direct effect...

Distinct abscisic acid signaling pathways for modulation of guard cell versus mesophyll cell potassium channels revealed by expression studies in Xenopus laevis oocytes

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Sutton, F.; Paul, S. S.; Wang, X. Q.; Assmann, S. M.; Evans, M. L. (Principal Investigator)

2000-01-01

Regulation of guard cell ion transport by abscisic acid (ABA) and in particular ABA inhibition of a guard cell inward K(+) current (I(Kin)) is well documented. However, little is known concerning ABA effects on ion transport in other plant cell types. Here we applied patch clamp techniques to mesophyll cell protoplasts of fava bean (Vicia faba cv Long Pod) plants and demonstrated ABA inhibition of an outward K(+) current (I(Kout)). When mesophyll cell protoplast mRNA (mesophyll mRNA) was expressed in Xenopus laevis oocytes, I(Kout) was generated that displayed similar properties to I(Kout) observed from direct analysis of mesophyll cell protoplasts. I(Kout) expressed by mesophyll mRNA-injected oocytes was inhibited by ABA, indicating that the ABA signal transduction pathway observed in mesophyll cells was preserved in the frog oocytes. Co-injection of oocytes with guard cell protoplast mRNA and cRNA for KAT1, an inward K(+) channel expressed in guard cells, resulted in I(Kin) that was similarly inhibited by ABA. However, oocytes co-injected with mesophyll mRNA and KAT1 cRNA produced I(Kin) that was not inhibited by ABA. These results demonstrate that the mesophyll-encoded signaling mechanism could not substitute for the guard cell pathway. These findings indicate that mesophyll cells and guard cells use distinct and different receptor types and/or signal transduction pathways in ABA regulation of K(+) channels.

Cellular mechanisms of nociception in the frog

Czech Academy of Sciences Publication Activity Database

Kuffler, D. P.; Lyfenko, Alla; Vyklický st., Ladislav; Vlachová, Viktorie

2002-01-01

Roč. 88, č. 4 (2002), s. 1843-1850 ISSN 0022-3077 R&D Projects: GA ČR GA305/00/1639; GA MŠk LN00B122 Grant - others:NATO(XX) Grant 977062 Institutional research plan: CEZ:AV0Z5011922 Keywords : cellular mechanisms of nociception * frog Subject RIV: FH - Neurology Impact factor: 3.743, year: 2002

Trichobothrial mediation of an aquatic escape response: Directional jumps by the fishing spider, Dolomedes triton, foil frog attacks

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Robert B. Suter

2003-07-01

Full Text Available Fishing spiders (Pisauridae frequent the surfaces of ponds and streams and thereby expose themselves to predation by a variety of aquatic and semi-aquatic vertebrates. To assess the possibility that the impressive jumps of fishing spiders from the water surface function in evading attacks by frogs, attacks by bullfrogs (Rana catesbiana and green frogs (R. clamitans on Dolomedes triton were studied. Both the attack dynamics of the frogs and the evasive behaviors of the spiders were recorded at 250 frames per second. A freeze-dried bullfrog, propelled toward spiders with acceleration, posture, and position that approximated the natural attack posture and dynamics, was used to assess the spiders' behavior. Qualitatively, the spiders responded to these mock-attacks just as they had to attacks by live frogs: jumping (N=29 jumps, 56.9% of instances, rearing the legs nearest the attacking frog (N=15, 29.4%, or showing no visible response (N=7, 13.7%. Spiders that jumped always did so away (in the vertical plane from the attack (mean =137° vs. vertical at 90° or horizontally toward the frog at 0°. The involvement of the trichobothria (leg hairs sensitive to air movements, and the eyes as sensory mediators of the evasion response was assessed. Spiders with deactivated trichobothria were significantly impaired relative to intact and sham-deactivated spiders, and relative to spiders in total darkness. Thus, functional trichobothria, unlike the eyes, are both necessary and sufficient mediators of the evasion response. Measurements of air flow during frog attacks suggest that an exponential rise in flow velocity is the airborne signature of an attack.

Inventory of the pool frog, newt and gulyxne in Forsmark 2012

International Nuclear Information System (INIS)

Collinder, Per

2013-01-01

On assignment from the Swedish Nuclear Fuel and Waste Management Co (SKB), Ekologigruppen AB carried out inventories of species populations during the summer of 2012. Species included in the study are described in three separate chapters of this report. The three species were pool frog Rana lessonae, great crested newt Triturus cristatus, and fen orchid Liparis loeselii. SKB will follow up the development of the local populations. Inventory of pool frogs are already a follow-up on a study carried out in 2011. Concern for these species is due to their protection within the EU system of species and habitat protection. Construction of the planned depository for used nuclear fuel will involve redirection of groundwater, which could potentially drain these wetlands. The three species pool frog, great crested newt and fen orchid are inventoried by well-documented procedures, which will allow repletion of the study at the same locals and according to the same methods during consequent years. The inventories are not complete in the sense that they would give number of individuals in a local population. Rather, the result should be regarded as an index for comparison and monitoring

Immune evasion strategies of ranaviruses and innate immune responses to these emerging pathogens.

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Grayfer, Leon; Andino, Francisco De Jesús; Chen, Guangchun; Chinchar, Gregory V; Robert, Jacques

2012-07-01

Ranaviruses (RV, Iridoviridae) are large double-stranded DNA viruses that infect fish, amphibians and reptiles. For ecological and commercial reasons, considerable attention has been drawn to the increasing prevalence of ranaviral infections of wild populations and in aquacultural settings. Importantly, RVs appear to be capable of crossing species barriers of numerous poikilotherms, suggesting that these pathogens possess a broad host range and potent immune evasion mechanisms. Indeed, while some of the 95-100 predicted ranavirus genes encode putative evasion proteins (e.g., vIFα, vCARD), roughly two-thirds of them do not share significant sequence identity with known viral or eukaryotic genes. Accordingly, the investigation of ranaviral virulence and immune evasion strategies is promising for elucidating potential antiviral targets. In this regard, recombination-based technologies are being employed to knock out gene candidates in the best-characterized RV member, Frog Virus (FV3). Concurrently, by using animal infection models with extensively characterized immune systems, such as the African clawed frog, Xenopus laevis, it is becoming evident that components of innate immunity are at the forefront of virus-host interactions. For example, cells of the macrophage lineage represent important combatants of RV infections while themselves serving as targets for viral infection, maintenance and possibly dissemination. This review focuses on the recent advances in the understanding of the RV immune evasion strategies with emphasis on the roles of the innate immune system in ranaviral infections.

Joint effects of pesticides and ultraviolet-B radiation on amphibian larvae

International Nuclear Information System (INIS)

Yu, Shuangying; Wages, Mike; Willming, Morgan; Cobb, George P.; Maul, Jonathan D.

2015-01-01

A combination of multiple stressors may be linked to global amphibian declines. Of these, pesticides and UVB radiation co-exposures were examined on the African clawed frog (Xenopus laevis) to provide information that may be useful for amphibian conservation. The independent action model and inferential statistics were used to examine interactions between pesticides (malathion, endosulfan, α-cypermethrin, or chlorothalonil) and environmentally relevant UVB exposures. UVB radiation alone caused 35–68% mortality and nearly 100% of malformations. Pesticides and UVB had additive effects on larval mortality; however, several non-additive effects (antagonistic and synergistic interactions) were observed for total body length. Insecticides mainly affected axial development, whereas UVB radiation caused high incidence of edema, gut malformations, and abnormal tail tips. These results suggest that sublethal developmental endpoints were more sensitive for detecting joint effects. This work has implications for amphibian risk assessments for ecosystems where pesticides and high UVB radiation may co-occur. - Highlights: • Interactive effects of UVB radiation-pesticide co-exposures were examined in frogs. • UVB radiation alone caused 35–68% mortality and nearly 100% of malformations. • Pesticides and UVB had additive effects on larval mortality. • Several non-additive effects were observed for total body length. • Amphibian risk assessments should consider UVB radiation exposure as a co-stressor. - Possible interactions between pesticides and UVB radiation support the idea that amphibian risk assessments should consider these co-stressors when high UVB radiation exposure is high.

Extinction of an introduced warm-climate alien species, Xenopus laevis, by extreme weather events.

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Tinsley, Richard C; Stott, Lucy C; Viney, Mark E; Mable, Barbara K; Tinsley, Matthew C

Invasive, non-native species represent a major threat to biodiversity worldwide. The African amphibian Xenopus laevis is widely regarded as an invasive species and a threat to local faunas. Populations originating at the Western Cape, South Africa, have been introduced on four continents, mostly in areas with a similar Mediterranean climate. Some introduced populations are also established in cooler environments where persistence for many decades suggests a capacity for long-term adaptation. In these cases, recent climate warming might enhance invasion ability, favouring range expansion, population growth and negative effects on native faunas. In the cool temperate UK, populations have been established for about 50 years in Wales and for an unknown period, probably >20 years, in England (Lincolnshire). Our field studies over 30 and 10 years, respectively, show that in favourable conditions there may be good recruitment, fast individual growth rates and large body size; maximum longevity exceeds 23 years. Nevertheless, areas of distribution remained limited, with numbers extinct. The winters of 2009-2010 and 2010-2011 experienced extreme cold and drought (December 2010 was the coldest in 120 years and the third driest in 100 years). The extinction of X. laevis in these areas indicates that even relatively long-established alien species remain vulnerable to rare extreme weather conditions.

Effects of CFT Legumine (5% Rotenone) on tadpole survival and metamorphosis of Chiricahua leopard frogs Lithobates chiricahuensis, Northern leopard frogs L. pipiens, and American bullfrogs L. catesbeianus

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Alvarez, Guillermo; Caldwell, Colleen A.; Kruse, Carter G.

2017-01-01

Amphibians may experience collateral effects if exposed to CFT Legumine (5% rotenone), a piscicide that is used to remove invasive fish. A series of 48-h static toxicity tests assessed the acute effects of CFT Legumine on multi-aged tadpoles of the federally listed Chiricahua leopard frog Lithobates chiricahuensis, the widespread northern leopard frog L. pipiens, and the increasingly invasive American bullfrog L. catesbeianus. At the earliest Gosner stages (GS 21–25), Chiricahua leopard frogs were more sensitive to CFT Legumine (median lethal concentration [LC50] = 0.41–0.58 mg/L) than American bullfrogs (LC50 = 0.63–0.69 mg/L) and northern leopard frogs (LC50 = 0.91 and 1.17 mg/L). As tadpoles developed (i.e., increase in GS), their sensitivity to rotenone decreased. In a separate series of 48-h static nonrenewal toxicity tests, tadpoles (GS 21–25 and GS 31–36) of all three species were exposed to piscicidal concentrations of CFT Legumine (0.5, 1.0, and 2.0 mg/L) to assess postexposure effects on metamorphosis. In survivors of all three species at both life stages, the time to tail resorption was nearly doubled in comparison with that of controls. For example, mid-age (GS 31–36) Chiricahua leopard frog tadpoles required 210.7 h to complete tail resorption, whereas controls required 108.5 h. However, because tail resorption is a relatively short period in metamorphosis, the total duration of development (days from posthatch to complete metamorphosis) and the final weight did not differ in either age-group surviving nominal concentrations of 0.5-, 1.0-, and 2.0-mg/L CFT Legumine relative to controls. This research demonstrates that the CFT Legumine concentrations commonly used in field applications to remove unwanted fish could result in considerable mortality of the earliest stages of Lithobates species. In addition to acute lethality, piscicide treatments may result in delayed tail resorption, which places the tadpoles at risk by increasing

The rediscovered Hula painted frog is a living fossil.

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Biton, Rebecca; Geffen, Eli; Vences, Miguel; Cohen, Orly; Bailon, Salvador; Rabinovich, Rivka; Malka, Yoram; Oron, Talya; Boistel, Renaud; Brumfeld, Vlad; Gafny, Sarig

2013-01-01

Amphibian declines are seen as an indicator of the onset of a sixth mass extinction of life on earth. Because of a combination of factors such as habitat destruction, emerging pathogens and pollutants, over 156 amphibian species have not been seen for several decades, and 34 of these were listed as extinct by 2004. Here we report the rediscovery of the Hula painted frog, the first amphibian to have been declared extinct. We provide evidence that not only has this species survived undetected in its type locality for almost 60 years but also that it is a surviving member of an otherwise extinct genus of alytid frogs, Latonia, known only as fossils from Oligocene to Pleistocene in Europe. The survival of this living fossil is a striking example of resilience to severe habitat degradation during the past century by an amphibian.

Genomic analysis of Xenopus organizer function

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Suhai Sándor

2006-06-01

Full Text Available Abstract Background Studies of the Xenopus organizer have laid the foundation for our understanding of the conserved signaling pathways that pattern vertebrate embryos during gastrulation. The two primary activities of the organizer, BMP and Wnt inhibition, can regulate a spectrum of genes that pattern essentially all aspects of the embryo during gastrulation. As our knowledge of organizer signaling grows, it is imperative that we begin knitting together our gene-level knowledge into genome-level signaling models. The goal of this paper was to identify complete lists of genes regulated by different aspects of organizer signaling, thereby providing a deeper understanding of the genomic mechanisms that underlie these complex and fundamental signaling events. Results To this end, we ectopically overexpress Noggin and Dkk-1, inhibitors of the BMP and Wnt pathways, respectively, within ventral tissues. After isolating embryonic ventral halves at early and late gastrulation, we analyze the transcriptional response to these molecules within the generated ectopic organizers using oligonucleotide microarrays. An efficient statistical analysis scheme, combined with a new Gene Ontology biological process annotation of the Xenopus genome, allows reliable and faithful clustering of molecules based upon their roles during gastrulation. From this data, we identify new organizer-related expression patterns for 19 genes. Moreover, our data sub-divides organizer genes into separate head and trunk organizing groups, which each show distinct responses to Noggin and Dkk-1 activity during gastrulation. Conclusion Our data provides a genomic view of the cohorts of genes that respond to Noggin and Dkk-1 activity, allowing us to separate the role of each in organizer function. These patterns demonstrate a model where BMP inhibition plays a largely inductive role during early developmental stages, thereby initiating the suites of genes needed to pattern dorsal tissues

Correlation between chloride flux via the mitochondria-rich cells and transepithelial water movement in isolated frog skin (Rana esculenta)

DEFF Research Database (Denmark)

Nielsen, Robert

1995-01-01

Antidiuretic hormone; chloride transport; electroosmosis; Frog skin; Intercalated cells; Local osmosis; Mitochondria-rich cells.......Antidiuretic hormone; chloride transport; electroosmosis; Frog skin; Intercalated cells; Local osmosis; Mitochondria-rich cells....

Lateral mobility of plasma membrane lipids in dividing Xenopus eggs.

Science.gov (United States)

Tetteroo, P A; Bluemink, J G; Dictus, W J; van Zoelen, E J; de Laat, S W

1984-07-01

The lateral mobility of plasma membrane lipids was analyzed during first cleavage of Xenopus laevis eggs by fluorescence photobleaching recovery (FPR) measurements, using the lipid analogs 5-(N-hexadecanoyl)aminofluorescein ("HEDAF") and 5-(N-tetradecanoyl)aminofluorescein ("TEDAF") as probes. The preexisting plasma membrane of the animal side showed an inhomogeneous, dotted fluorescence pattern after labeling and the lateral mobility of both probes used was below the detection limits of the FPR method (D much less than 10(-10) cm2/sec). In contrast, the preexisting plasma membrane of the vegetal side exhibited homogeneous fluorescence and the lateral diffusion coefficient of both probes used was relatively high (HEDAF, D = 2.8 X 10(-8) cm2/sec; TEDAF, D = 2.4 X 10(-8) cm2/sec). In the cleaving egg visible transfer of HEDAF or TEDAF from prelabeled plasma membrane to the new membrane in the furrow did not occur, even on the vegetal side. Upon labeling during cleavage, however, the new membrane was uniformly labeled and both probes were mobile, as in the vegetal preexisting plasma membrane. These data show that the membrane of the dividing Xenopus egg comprises three macrodomains: (i) the animal preexisting plasma membrane; (ii) the vegetal preexisting plasma membrane; (iii) the new furrow membrane.

Old World frog and bird vocalizations contain prominent ultrasonic harmonics

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Narins, Peter M.; Feng, Albert S.; Lin, Wenyu; Schnitzler, Hans-Ulrich; Denzinger, Annette; Suthers, Roderick A.; Xu, Chunhe

2004-02-01

Several groups of mammals such as bats, dolphins and whales are known to produce ultrasonic signals which are used for navigation and hunting by means of echolocation, as well as for communication. In contrast, frogs and birds produce sounds during night- and day-time hours that are audible to humans; their sounds are so pervasive that together with those of insects, they are considered the primary sounds of nature. Here we show that an Old World frog (Amolops tormotus) and an oscine songbird (Abroscopus albogularis) living near noisy streams reliably produce acoustic signals that contain prominent ultrasonic harmonics. Our findings provide the first evidence that anurans and passerines are capable of generating tonal ultrasonic call components and should stimulate the quest for additional ultrasonic species.

Citizen Science Program Shows Urban Areas Have Lower Occurrence of Frog Species, but Not Accelerated Declines.

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Martin J Westgate

Full Text Available Understanding the influence of landscape change on animal populations is critical to inform biodiversity conservation efforts. A particularly important goal is to understand how urban density affects the persistence of animal populations through time, and how these impacts can be mediated by habitat provision; but data on this question are limited for some taxa. Here, we use data from a citizen science monitoring program to investigate the effect of urbanization on patterns of frog species richness and occurrence over 13 years. Sites surrounded by a high proportion of bare ground (a proxy for urbanization had consistently lower frog occurrence, but we found no evidence that declines were restricted to urban areas. Instead, several frog species showed declines in rural wetlands with low-quality habitat. Our analysis shows that urban wetlands had low but stable species richness; but also that population trajectories are strongly influenced by vegetation provision in both the riparian zone and the wider landscape. Future increases in the extent of urban environments in our study area are likely to negatively impact populations of several frog species. However, existing urban areas are unlikely to lose further frog species in the medium term. We recommend that landscape planning and management focus on the conservation and restoration of rural wetlands to arrest current declines, and the revegetation of urban wetlands to facilitate the re-expansion of urban-sensitive species.

FoxA4 favours notochord formation by inhibiting contiguous mesodermal fates and restricts anterior neural development in Xenopus embryos.

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Sabrina Murgan

Full Text Available In vertebrates, the embryonic dorsal midline is a crucial signalling centre that patterns the surrounding tissues during development. Members of the FoxA subfamily of transcription factors are expressed in the structures that compose this centre. Foxa2 is essential for dorsal midline development in mammals, since knock-out mouse embryos lack a definitive node, notochord and floor plate. The related gene foxA4 is only present in amphibians. Expression begins in the blastula -chordin and -noggin expressing centre (BCNE and is later restricted to the dorsal midline derivatives of the Spemann's organiser. It was suggested that the early functions of mammalian foxa2 are carried out by foxA4 in frogs, but functional experiments were needed to test this hypothesis. Here, we show that some important dorsal midline functions of mammalian foxa2 are exerted by foxA4 in Xenopus. We provide new evidence that the latter prevents the respecification of dorsal midline precursors towards contiguous fates, inhibiting prechordal and paraxial mesoderm development in favour of the notochord. In addition, we show that foxA4 is required for the correct regionalisation and maintenance of the central nervous system. FoxA4 participates in constraining the prospective rostral forebrain territory during neural specification and is necessary for the correct segregation of the most anterior ectodermal derivatives, such as the cement gland and the pituitary anlagen. Moreover, the early expression of foxA4 in the BCNE (which contains precursors of the whole forebrain and most of the midbrain and hindbrain is directly required to restrict anterior neural development.

Oxidative stress induced in PCB 126-exposed northern leopard frogs, Rana pipiens

Science.gov (United States)

Huang, Y.-W.; Hoffman, D.J.; Karasov, W.H.

2007-01-01

Northern leopard frogs Rana pipiens exposed to PCB 126 (3,3',4,4',5-pentachlorobiphenyl) were examined for hepatic oxidative stress. In a dose-response study, northern leopard frogs were injected intraperitoneally with either PCB 126 in corn oil (0.2, 0.7, 2.3, or 7.8 mg/kg body weight) or corn oil alone. In a time-course study, frogs received 7.8 mg/kg or corn oil alone, and were examined at 1, 2, 3, and 4 wk after dosing. Hepatic concentrations of reduced glutathione (GSH), thiobarbituric acid-reactive substances (TBARS), and total sulfhydryls (total SH), as well as activities of glutathione peroxidase (GSH-P), GSSG reductase (GSSG-R), glucose-6-phosphate dehydrogenase (G-6-PDH), and glutathione S-transferase (GSH-S-T) were measured. In the dose-response experiment, few effects were apparent 1 wk after dosing. In the time-course experiment, significant changes were observed in the 7.8-mg/kg group at 2 wk or more posttreatment. Hepatic concentrations of GSH and TBARS were higher than in corresponding controls at wk 3 and 4; the activities of GSSG-R and GSH-S-T were higher than in controls at wk 2 and 4; and the activity of G-6-PDH was increased at wk 2 and 4. These data collectively indicate that altered glutathione metabolism and oxidative stress occurred and were indicative of both toxicity and induction of protective mechanisms in frogs exposed to PCB. A similar delay in response was reported in fish and may relate to lower metabolic rate and physiological reactions in ectothermic vertebrates

Oxidative stress induced in PCB 126-exposed northern leopard frogs, Rana pipiens.

Science.gov (United States)

Huang, Yue-wern; Hoffman, David J; Karasov, William H

2007-04-15

Northern leopard frogs Rana pipiens exposed to PCB 126 (3,3',4,4',5-pentachlorobiphenyl) were examined for hepatic oxidative stress. In a dose-response study, northern leopard frogs were injected intraperitoneally with either PCB 126 in corn oil (0.2, 0.7, 2.3, or 7.8 mg/kg body weight) or corn oil alone. In a time-course study, frogs received 7.8 mg/kg or corn oil alone, and were examined at 1, 2, 3, and 4 wk after dosing. Hepatic concentrations of reduced glutathione (GSH), thiobarbituric acid-reactive substances (TBARS), and total sulfhydryls (total SH), as well as activities of glutathione peroxidase (GSH-P), GSSG reductase (GSSG-R), glucose-6-phosphate dehydrogenase (G-6-PDH), and glutathione S-transferase (GSH-S-T) were measured. In the dose-response experiment, few effects were apparent 1 wk after dosing. In the time-course experiment, significant changes were observed in the 7.8-mg/kg group at 2 wk or more posttreatment. Hepatic concentrations of GSH and TBARS were higher than in corresponding controls at wk 3 and 4; the activities of GSSG-R and GSH-S-T were higher than in controls at wk 2 and 4; and the activity of G-6-PDH was increased at wk 2 and 4. These data collectively indicate that altered glutathione metabolism and oxidative stress occurred and were indicative of both toxicity and induction of protective mechanisms in frogs exposed to PCB. A similar delay in response was reported in fish and may relate to lower metabolic rate and physiological reactions in ectothermic vertebrates.

Evolutionary and natural history of the turtle frog, Myobatrachus gouldii, a bizarre myobatrachid frog in the southwestern Australian biodiversity hotspot.

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Samantha Vertucci

Full Text Available Southwest Australia (SWA is a global biodiversity hotspot and a centre of diversity and endemism for the Australo-Papuan myobatrachid frogs. Myobatrachus gouldii (the turtle frog has a highly derived morphology associated with its forward burrowing behaviour, largely subterranean habit, and unusual mode of reproduction. Its sister genera Metacrinia and Arenophryne have restricted distributions in Western Australia with significant phylogeographic structure, leading to the recent description of a new species in the latter. In contrast, Myobatrachus is distributed widely throughout SWA over multiple climatic zones, but little is known of its population structure, geographic variation in morphology, or reproduction. We generated molecular and morphological data to test for genetic and morphological variation, and to assess whether substrate specialisation in this species may have led to phylogeographic structuring similar to that of other plant and animal taxa in SWA. We assembled sequence data for one mitochondrial and four nuclear DNA loci (3628 base pairs for 42 turtle frogs sampled throughout their range. Likelihood phylogenetic analyses revealed shallow phylogeographic structure in the mtDNA locus (up to 3.3% genetic distance and little variation in three of the four nDNA loci. The mtDNA haplotype network suggests five geographically allopatric groups, with no shared haplotypes between regions. These geographic patterns are congruent with several other SWA species, with genetic groups restricted to major hydrological divisions, the Swan Coastal Plain, and the Darling Scarp. The geographically structured genetic groups showed no evidence of significant morphological differentiation (242 individuals, and there was little sexual size dimorphism, but subtle differences in reproductive traits suggest more opportunistic breeding in lower rainfall zones. Call data were compared to sister genera Metacrinia and Arenophryne and found to be highly

Terrestrial activity and conservation of adult California red-legged frogs Rana aurora draytonii in coastal forests and grasslands

Science.gov (United States)

Bulger, J.B.; Scott, N.J.; Seymour, R.B.

2003-01-01

The federally threatened California red-legged frog Rana aurora draytonii occupies both aquatic and terrestrial habitats in its adult life stage. The terrestrial activities of this species are not well known and require documentation to assist in the development of appropriate levels of protection under the US Endangered Species Act. We studied the terrestrial activities of radio-tagged red-legged frogs (n = 8-26) inhabiting a coastal watershed in Santa Cruz County, California, during 1997-1998. In particular, we investigated (1) the use of terrestrial habitats by non-migrating adults in relation to season, breeding chronology, and precipitation, and (2) adult migration behavior, including seasonal timing, duration, distances traveled, and the use of corridors. Non-migrating red-legged frogs occupied terrestrial habitats briefly (median = 4-6 days) following infrequent summer rains, but resided nearly continuously on land (median = 20-30 days) from the onset of the winter wet-season until breeding activities commenced 1-2 months later. All of the non-migrating frogs remained within 130 m of their aquatic site of residence (median days), despite frequent and copious rainfall. Adult migration to and from breeding sites occurred from late October through mid-May (wet season). We monitored 25 migration events between aquatic sites that were 200-2800 m apart. Short distance movements ( days, longer movements required up to 2 months. Most migrating frogs moved overland in approximately straight lines to target sites without apparent regard to vegetation type or topography. Riparian corridors were neither essential nor preferred as migration routes. Frogs traveling overland occurred in upland habitats as far as 500 m from water. Approximately 11-22% of the adult population was estimated to migrate to and from breeding sites annually, whereas the bulk of the adult population was resident at these sites. Adequate protection of red-legged frog populations inhabiting

Heterotrimeric Kinesin II Is the Microtubule Motor Protein Responsible for Pigment Dispersion in Xenopus Melanophores

Science.gov (United States)

Tuma, M. Carolina; Zill, Andrew; Le Bot, Nathalie; Vernos, Isabelle; Gelfand, Vladimir

1998-01-01

Melanophores move pigment organelles (melanosomes) from the cell center to the periphery and vice-versa. These bidirectional movements require cytoplasmic microtubules and microfilaments and depend on the function of microtubule motors and a myosin. Earlier we found that melanosomes purified from Xenopus melanophores contain the plus end microtubule motor kinesin II, indicating that it may be involved in dispersion (Rogers, S.L., I.S. Tint, P.C. Fanapour, and V.I. Gelfand. 1997. Proc. Natl. Acad. Sci. USA. 94: 3720–3725). Here, we generated a dominant-negative construct encoding green fluorescent protein fused to the stalk-tail region of Xenopus kinesin-like protein 3 (Xklp3), the 95-kD motor subunit of Xenopus kinesin II, and introduced it into melanophores. Overexpression of the fusion protein inhibited pigment dispersion but had no effect on aggregation. To control for the specificity of this effect, we studied the kinesin-dependent movement of lysosomes. Neither dispersion of lysosomes in acidic conditions nor their clustering under alkaline conditions was affected by the mutant Xklp3. Furthermore, microinjection of melanophores with SUK4, a function-blocking kinesin antibody, inhibited dispersion of lysosomes but had no effect on melanosome transport. We conclude that melanosome dispersion is powered by kinesin II and not by conventional kinesin. This paper demonstrates that kinesin II moves membrane-bound organelles. PMID:9852150

Comparative pathology and ecological implications of two myxosporean parasites in native Australian frogs and the invasive cane toad.

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Ashlie Hartigan

Full Text Available Myxosporean parasites Cystodiscus axonis and C. australis are pathogens of native and exotic Australian frog species. The pathology and ecological outcomes of infection with these parasites were investigated in this study. Gliosis was correlated to Cystodiscus axonis plasmodia in the brains of (9/60 tadpoles and (3/9 adult endangered Green and golden bell frogs using ordinal regression. Severe host reactions to C. axonis (haemorrhage, necrosis, and vasulitis were observed in the brains of threatened Southern bell frogs (8/8, critically endangered Booroolong frogs (15/44 and Yellow spotted bell frogs (3/3. Severe brain lesions were associated with behavioural changes, neurological dysfunction, and spontaneous death. Both C. axonis and C. australis develop in the bile ducts of tadpoles, the plasmodia were significantly associated with biliary hyperplasia, inflammation and the loss of hepatocytes in (34/72 Green and golden bell frog tadpoles using ordinal regression. These lesions were so severe that in some cases 70% of the total liver was diseased. Normal liver function in tadpoles is necessary for metamorphosis, metabolism, and immune function. We postulate that this extensive liver damage would have significant host health impacts. Severe hepatic myxosporidiosis was more prevalent in tadpoles examined in autumn and winter (overwintered, suggestive of delayed metamorphosis in infected tadpoles, which would have serious flow-on effects in small populations. We compared the sensitivity of histopathology and species-specific PCR in the detection of C. australis and C. axonis. PCR was determined to be the most sensitive method (detection limit 1 myxospore equivalent of ribosomal DNA. Histology, however, had the advantage of assessing the impact of the parasite on the host. It was concluded that these parasites have the potential for significant ecological impacts, because of their high prevalence of infection and their ability to cause disease in

The repetitive portion of the Xenopus IgH Mu switch region mediates orientation-dependent class switch recombination.

Science.gov (United States)

Zhang, Zheng Z; Pannunzio, Nicholas R; Lu, Zhengfei; Hsu, Ellen; Yu, Kefei; Lieber, Michael R

2015-10-01

Vertebrates developed immunoglobulin heavy chain (IgH) class switch recombination (CSR) to express different IgH constant regions. Most double-strand breaks for Ig CSR occur within the repetitive portion of the switch regions located upstream of each set of constant domain exons for the Igγ, Igα or Igϵ heavy chain. Unlike mammalian switch regions, Xenopus switch regions do not have a high G-density on the non-template DNA strand. In previous studies, when Xenopus Sμ DNA was moved to the genome of mice, it is able to support substantial CSR when it is used to replace the murine Sγ1 region. Here, we tested both the 2kb repetitive portion and the 4.6 kb full-length portions of the Xenopus Sμ in both their natural (forward) orientation relative to the constant domain exons, as well as the opposite (reverse) orientation. Consistent with previous work, we find that the 4.6 kb full-length Sμ mediates similar levels of CSR in both the forward and reverse orientations. Whereas, the forward orientation of the 2kb portion can restore the majority of the CSR level of the 4.6 kb full-length Sμ, the reverse orientation poorly supports R-looping and no CSR. The forward orientation of the 2kb repetitive portion has more GG dinucleotides on the non-template strand than the reverse orientation. The correlation of R-loop formation with CSR efficiency, as demonstrated in the 2kb repetitive fragment of the Xenopus switch region, confirms a role played by R-looping in CSR that appears to be conserved through evolution. Copyright © 2015 Elsevier Ltd. All rights reserved.

Building the Future: Post-transcriptional Regulation of Cell Fate Decisions Prior to the Xenopus Midblastula Transition.

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Sheets, Michael D

2015-01-01

In all animals, a critical period in early development is when embryonic cells switch from relying solely upon maternally deposited RNAs and proteins to relying upon molecules encoded by the zygotic genome. Xenopus embryos have served as a model for examining this switch, as well as the maternally controlled stages that prepare for it. In Xenopus, the robust activation of zygotic transcription occurs at the 12th cleavage division and is referred to as the midblastula transition (MBT). Prior to MBT, gene expression is regulated by post-transcriptional events including mRNA and protein localization, protein post-translational modification, and mRNA translation. After the MBT, appropriate transcriptional regulation of the zygotic genome becomes critical and predominates. However, it is important to realize that the first key cell fate decisions that have profound impacts on development occur prior to the MBT and these are governed by regulating the expression of maternally deposited regulatory mRNAs and proteins. In this chapter, I will discuss post-transcriptional mechanisms that function during the maternal stages of Xenopus development with an emphasis on mechanisms known to directly modulate cell fate decisions. Emerging approaches and technologies that will help better understand this phase of development will also be discussed. © 2015 Elsevier Inc. All rights reserved.

Electron microscopy of the amphibian model systems Xenopus laevis and Ambystoma mexicanum.

Science.gov (United States)

Kurth, Thomas; Berger, Jürgen; Wilsch-Bräuninger, Michaela; Kretschmar, Susanne; Cerny, Robert; Schwarz, Heinz; Löfberg, Jan; Piendl, Thomas; Epperlein, Hans H

2010-01-01

In this chapter we provide a set of different protocols for the ultrastructural analysis of amphibian (Xenopus, axolotl) tissues, mostly of embryonic origin. For Xenopus these methods include: (1) embedding gastrulae and tailbud embryos into Spurr's resin for TEM, (2) post-embedding labeling of methacrylate (K4M) and cryosections through adult and embryonic epithelia for correlative LM and TEM, and (3) pre-embedding labeling of embryonic tissues with silver-enhanced nanogold. For the axolotl (Ambystoma mexicanum) we present the following methods: (1) SEM of migrating neural crest (NC) cells; (2) SEM and TEM of extracellular matrix (ECM) material; (3) Cryo-SEM of extracellular matrix (ECM) material after cryoimmobilization; and (4) TEM analysis of hyaluronan using high-pressure freezing and HABP labeling. These methods provide exemplary approaches for a variety of questions in the field of amphibian development and regeneration, and focus on cell biological issues that can only be answered with fine structural imaging methods, such as electron microscopy. Copyright © 2010 Elsevier Inc. All rights reserved.

Hibernal habitat selection by Wood Frogs (Lithobates sylvaticus) in a northern New England montane landscape

Science.gov (United States)

Groff, Luke A.; Calhoun, Aram J.K.; Loftin, Cynthia S.

2016-01-01

Poikilothermic species, such as amphibians, endure harsh winter conditions via freeze-tolerance or freeze-avoidance strategies. Freeze-tolerance requires a suite of complex, physiological mechanisms (e.g., cryoprotectant synthesis); however, behavioral strategies (e.g., hibernal habitat selection) may be used to regulate hibernaculum temperatures and promote overwintering survival. We investigated the hibernal ecology of the freeze-tolerant Wood Frog (Lithobates sylvaticus) in north-central Maine. Our objectives were to characterize the species hibernaculum microclimate (temperature, relative humidity), evaluate hibernal habitat selection, and describe the spatial arrangement of breeding, post-breeding, and hibernal habitats. We monitored 15 frogs during two winters (2011/12: N = 10; 2012/13: N = 5), measured hibernal habitat features at micro (2 m) and macro (10 m) spatial scales, and recorded microclimate hourly in three strata (hibernaculum, leaf litter, ambient air). We compared these data to that of 57 random locations with logistic regression models, Akaike Information Criterion, and Kolmogorov–Smirnov tests. Hibernaculum microclimate was significantly different and less variable than leaf litter, ambient air, and random location microclimate. Model averaging indicated that canopy cover (−), leaf litter depth (+), and number of logs and stumps (+; microhabitat only) were important predictors of Wood Frog hibernal habitat. These habitat features likely act to insulate hibernating frogs from extreme and variable air temperatures. For example, decreased canopy cover facilitates increased snowpack depth and earlier snowpack accumulation and melt. Altered winter temperature and precipitation patterns attributable to climate change may reduce snowpack insulation, facilitate greater temperature variation in the underlying hibernacula, and potentially compromise Wood Frog winter survival.

Road Impacts on Abundance, Call Traits, and Body Size of Rainforest Frogs in Northeast Australia

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Conrad J. Hoskin

2010-09-01

Full Text Available Frogs are potentially sensitive indicators of road impacts, with studies indicating particular susceptibility to road mortality. Calling, i.e., breeding, behavior could also be affected by traffic noise. We investigated effects on frog abundance and calling behavior where a busy highway crosses rainforest stream breeding habitat in northeast Australia. Frog abundance was repeatedly surveyed along five stream transects during a summer breeding season. Abundance of two species, Litoria rheocola and Austrochaperina pluvialis, increased significantly with perpendicular distance from the road along two transects. No trends in abundance were detected for A. pluvialis on two other transects where it was common, or for Litoria serrata on one transect where abundance was sufficient for analysis. Both species with lowered abundance near the road, L. rheocola and A. pluvialis, are rare in road kill statistics along this highway, suggesting road mortality is not the cause of reduced frog abundance near the road. We postulate that lowered abundance may reflect traffic noise effects. We analyzed calls of the International Union for Conservation of Nature endangered species L. rheocola along the one stream transect on which it was common. We found significant trends in two call traits over a very fine scale: both call rate and dominant frequency were significantly higher closer to the road. Furthermore, males were significantly smaller closer to the road. These call and body size trends most likely reflect road impacts, but resolving these is complicated by correlations between traits. Potential mechanisms, effects on fitness, and management recommendations to mitigate the impacts of roads on frogs are outlined.

Autometallographic tracing of mercury in frog liver

International Nuclear Information System (INIS)

Loumbourdis, N.S.; Danscher, G.

2004-01-01

The distribution of mercury in the liver of the frog Rana ridibunda with the autometallographic method was investigated. The mercury specific autometallographic (HgS/Se AMG ) technique is a sensitive histochemical approach for tracing mercury in tissues from mercury-exposed organisms. Mercury accumulates in vivo as mercury sulphur/mercury selenium nanocrystals that can be silver-enhanced. Thus, only a fraction of the Hg can be visualized. Six animals were exposed for one day and another group of six animals for 6 days in 1 ppm mercury (as HgCI 2 ) dissolved in fresh water. A third group of six animals, served as controls, were sacrificed the day of arrival at the laboratory. First, mercury appears in the blood plasma and erythrocytes. Next, mercury moves to hepatocytes and in the apical part of the cells, that facing bile canaliculi. In a next step, mercury appears in the endothelial and Kupffer cells. It seems likely that, the mercury of hepatocytes moves through bile canaliculi to the gut, most probably bound to glutathione and/or other similar ligands. Most probably, the endothelial and Kupffer cells comprise the first line of defense against metal toxicity. - Frogs can be good bioindicators of mercury

Physiologically-induced changes in proopiomelanocortin mRNA levels in the pituitary gland of the amphibian Xenopus laevis.

Science.gov (United States)

Martens, G J; Weterings, K A; van Zoest, I D; Jenks, B G

1987-03-13

In the pars intermedia of the pituitary gland of the amphibian Xenopus laevis the level of mRNA encoding proopiomelanocortin (POMC), the precursor protein for alpha-melanophore-stimulating hormone (alpha-MSH), is shown to be dependent on physiological parameters. POMC mRNA levels in the pars intermedia of black-background-adapted Xenopus are much higher than those of white-adapted animals. These physiological changes in POMC mRNA levels are tissue-specific because they were not found in the pars distalis of the pituitary gland. Background transfer experiments revealed that modulation of POMC gene activity is much slower than changes in the secretion of alpha-MSH.

Insights on the evolution of prolyl 3-hydroxylation sites from comparative analysis of chicken and Xenopus fibrillar collagens.

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David M Hudson

2011-05-01

Full Text Available Recessive mutations that prevent 3-hydroxyproline formation in type I collagen have been shown to cause forms of osteogenesis imperfecta. In mammals, all A-clade collagen chains with a GPP sequence at the A1 site (P986, except α1(III, have 3Hyp at residue P986. Available avian, amphibian and reptilian type III collagen sequences from the genomic database (Ensembl all differ in sequence motif from mammals at the A1 site. This suggests a potential evolutionary distinction in prolyl 3-hydroxylation between mammals and earlier vertebrates. Using peptide mass spectrometry, we confirmed that this 3Hyp site is fully occupied in α1(III from an amphibian, Xenopus laevis, as it is in chicken. A thorough characterization of all predicted 3Hyp sites in collagen types I, II, III and V from chicken and xenopus revealed further differences in the pattern of occupancy of the A3 site (P707. In mammals only α2(I and α2(V chains had any 3Hyp at the A3 site, whereas in chicken all α-chains except α1(III had A3 at least partially 3-hydroxylated. The A3 site was also partially 3-hydroxylated in xenopus α1(I. Minor differences in covalent cross-linking between chicken, xenopus and mammal type I and III collagens were also found as a potential index of evolving functional differences. The function of 3Hyp is still unknown but observed differences in site occupancy during vertebrate evolution are likely to give important clues.

Insights on the evolution of prolyl 3-hydroxylation sites from comparative analysis of chicken and Xenopus fibrillar collagens.

Science.gov (United States)

Hudson, David M; Weis, Maryann; Eyre, David R

2011-05-03

Recessive mutations that prevent 3-hydroxyproline formation in type I collagen have been shown to cause forms of osteogenesis imperfecta. In mammals, all A-clade collagen chains with a GPP sequence at the A1 site (P986), except α1(III), have 3Hyp at residue P986. Available avian, amphibian and reptilian type III collagen sequences from the genomic database (Ensembl) all differ in sequence motif from mammals at the A1 site. This suggests a potential evolutionary distinction in prolyl 3-hydroxylation between mammals and earlier vertebrates. Using peptide mass spectrometry, we confirmed that this 3Hyp site is fully occupied in α1(III) from an amphibian, Xenopus laevis, as it is in chicken. A thorough characterization of all predicted 3Hyp sites in collagen types I, II, III and V from chicken and xenopus revealed further differences in the pattern of occupancy of the A3 site (P707). In mammals only α2(I) and α2(V) chains had any 3Hyp at the A3 site, whereas in chicken all α-chains except α1(III) had A3 at least partially 3-hydroxylated. The A3 site was also partially 3-hydroxylated in xenopus α1(I). Minor differences in covalent cross-linking between chicken, xenopus and mammal type I and III collagens were also found as a potential index of evolving functional differences. The function of 3Hyp is still unknown but observed differences in site occupancy during vertebrate evolution are likely to give important clues.

Calling at the highway: The spatiotemporal constraint of road noise on Pacific chorus frog communication.

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Nelson, Danielle V; Klinck, Holger; Carbaugh-Rutland, Alexander; Mathis, Codey L; Morzillo, Anita T; Garcia, Tiffany S

2017-01-01

Loss of acoustic habitat due to anthropogenic noise is a key environmental stressor for vocal amphibian species, a taxonomic group that is experiencing global population declines. The Pacific chorus frog ( Pseudacris regilla ) is the most common vocal species of the Pacific Northwest and can occupy human-dominated habitat types, including agricultural and urban wetlands. This species is exposed to anthropogenic noise, which can interfere with vocalizations during the breeding season. We hypothesized that Pacific chorus frogs would alter the spatial and temporal structure of their breeding vocalizations in response to road noise, a widespread anthropogenic stressor. We compared Pacific chorus frog call structure and ambient road noise levels along a gradient of road noise exposures in the Willamette Valley, Oregon, USA. We used both passive acoustic monitoring and directional recordings to determine source level (i.e., amplitude or volume), dominant frequency (i.e., pitch), call duration, and call rate of individual frogs and to quantify ambient road noise levels. Pacific chorus frogs were unable to change their vocalizations to compensate for road noise. A model of the active space and time ("spatiotemporal communication") over which a Pacific chorus frog vocalization could be heard revealed that in high-noise habitats, spatiotemporal communication was drastically reduced for an individual. This may have implications for the reproductive success of this species, which relies on specific call repertoires to portray relative fitness and attract mates. Using the acoustic call parameters defined by this study (frequency, source level, call rate, and call duration), we developed a simplified model of acoustic communication space-time for this species. This model can be used in combination with models that determine the insertion loss for various acoustic barriers to define the impact of anthropogenic noise on the radius of communication in threatened species

Apomorphine effects on frog locomotor behavior

OpenAIRE

Chu, Joanne; Wilczynski, Walter

2007-01-01

The neuroanatomical pathways of the DA systems have been shown to be largely conserved across many vertebrate taxa. It is less certain whether the structural similarities seen between mammals and amphibians reflect a similar functional homology. DA is well known for its role in facilitating motor behaviors in mammals. We examined whether a similar role for DA exists in amphibians using the Northern Leopard Frog (Rana pipiens). We investigated the effects of the nonspecific DA agonist, apomorp...

Exploring the Underlying Mechanisms of the Xenopus laevis Embryonic Cell Cycle.

Science.gov (United States)

Zhang, Kun; Wang, Jin

2018-05-31

The cell cycle is an indispensable process in proliferation and development. Despite significant efforts, global quantification and physical understanding are still challenging. In this study, we explored the mechanisms of the Xenopus laevis embryonic cell cycle by quantifying the underlying landscape and flux. We uncovered the Mexican hat landscape of the Xenopus laevis embryonic cell cycle with several local basins and barriers on the oscillation path. The local basins characterize the different phases of the Xenopus laevis embryonic cell cycle, and the local barriers represent the checkpoints. The checkpoint mechanism of the cell cycle is revealed by the landscape basins and barriers. While landscape shape determines the stabilities of the states on the oscillation path, the curl flux force determines the stability of the cell cycle flow. Replication is fundamental for biology of living cells. We quantify the input energy (through the entropy production) as the thermodynamic requirement for initiation and sustainability of single cell life (cell cycle). Furthermore, we also quantify curl flux originated from the input energy as the dynamical requirement for the emergence of a new stable phase (cell cycle). This can provide a new quantitative insight for the origin of single cell life. In fact, the curl flux originated from the energy input or nutrition supply determines the speed and guarantees the progression of the cell cycle. The speed of the cell cycle is a hallmark of cancer. We characterized the quality of the cell cycle by the coherence time and found it is supported by the flux and energy cost. We are also able to quantify the degree of time irreversibility by the cross correlation function forward and backward in time from the stochastic traces in the simulation or experiments, providing a way for the quantification of the time irreversibility and the flux. Through global sensitivity analysis upon landscape and flux, we can identify the key elements for

Endemic infection of the amphibian chytrid fungus in a frog community post-decline.

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Richard W R Retallick

2004-11-01

Full Text Available The chytrid fungus Batrachochytrium dendrobatidis has been implicated in the decline and extinction of numerous frog species worldwide. In Queensland, Australia, it has been proposed as the cause of the decline or apparent extinction of at least 14 high-elevation rainforest frog species. One of these, Taudactylus eungellensis, disappeared from rainforest streams in Eungella National Park in 1985-1986, but a few remnant populations were subsequently discovered. Here, we report the analysis of B. dendrobatidis infections in toe tips of T. eungellensis and sympatric species collected in a mark-recapture study between 1994 and 1998. This longitudinal study of the fungus in individually marked frogs sheds new light on the effect of this threatening infectious process in field, as distinct from laboratory, conditions. We found a seasonal peak of infection in the cooler months, with no evidence of interannual variation. The overall prevalence of infection was 18% in T. eungellensis and 28% in Litoria wilcoxii/jungguy, a sympatric frog that appeared not to decline in 1985-1986. No infection was found in any of the other sympatric species. Most importantly, we found no consistent evidence of lower survival in T. eungellensis that were infected at the time of first capture, compared with uninfected individuals. These results refute the hypothesis that remnant populations of T. eungellensis recovered after a B. dendrobatidis epidemic because the pathogen had disappeared. They show that populations of T. eungellensis now persist with stable, endemic infections of B. dendrobatidis.

Endemic infection of the amphibian chytrid fungus in a frog community post-decline.

Science.gov (United States)

Retallick, Richard W R; McCallum, Hamish; Speare, Rick

2004-11-01

The chytrid fungus Batrachochytrium dendrobatidis has been implicated in the decline and extinction of numerous frog species worldwide. In Queensland, Australia, it has been proposed as the cause of the decline or apparent extinction of at least 14 high-elevation rainforest frog species. One of these, Taudactylus eungellensis, disappeared from rainforest streams in Eungella National Park in 1985-1986, but a few remnant populations were subsequently discovered. Here, we report the analysis of B. dendrobatidis infections in toe tips of T. eungellensis and sympatric species collected in a mark-recapture study between 1994 and 1998. This longitudinal study of the fungus in individually marked frogs sheds new light on the effect of this threatening infectious process in field, as distinct from laboratory, conditions. We found a seasonal peak of infection in the cooler months, with no evidence of interannual variation. The overall prevalence of infection was 18% in T. eungellensis and 28% in Litoria wilcoxii/jungguy, a sympatric frog that appeared not to decline in 1985-1986. No infection was found in any of the other sympatric species. Most importantly, we found no consistent evidence of lower survival in T. eungellensis that were infected at the time of first capture, compared with uninfected individuals. These results refute the hypothesis that remnant populations of T. eungellensis recovered after a B. dendrobatidis epidemic because the pathogen had disappeared. They show that populations of T. eungellensis now persist with stable, endemic infections of B. dendrobatidis.

The role of nitric oxide during embryonic epidermis development of Xenopus laevis

Czech Academy of Sciences Publication Activity Database

Tománková, Silvie; Abaffy, Pavel; Šindelka, Radek

2017-01-01

Roč. 6, č. 6 (2017), s. 862-871 ISSN 2046-6390 R&D Projects: GA AV ČR LK21305; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:86652036 Keywords : Development * Nitric oxide * Epidermis * Xenopus laevis Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Developmental biology Impact factor: 2.095, year: 2016

Endocrine-disrupting effects and reproductive toxicity of low dose MCLR on male frogs (Rana nigromaculata) in vivo

Energy Technology Data Exchange (ETDEWEB)

Jia, Xiuying; Cai, Chenchen; Wang, Jia; Gao, Nana; Zhang, Hangjun, E-mail: zhanghangjun@gmail.com

2014-10-15

Highlights: • Low-dose MCLR (1 μg/L) elicits a potential ecological effect on amphibian populations. • MCLR can induce abnormal sperm morphologies and activities on male frogs. • MCLR can induce a decrease in serum testosterone and an increase in serum estradiol of male frogs. • MCLR can increase SF-1 protein levels and decrease P450 aromatase levels in the gonads of frogs. - Abstract: Toxic cyanobacterial blooms are potential global threats to aquatic ecosystems and human health. The World Health Organization has set a provisional guideline limit of 1 μg/L microcystin-LR (MCLR) in freshwater. However, MCLR concentrations in several water bodies have exceeded this level. Despite this recommended human safety standard, MCLR-induced endocrine-disrupting effects and reproductive toxicity on male frog (Rana nigromaculata) were demonstrated in this study. Results showed that sperm motility and sperm count were significantly and negatively correlated with exposure time and concentration. By contrast, abnormal sperm rate was positively correlated with both parameters. Ultrastructural observation results revealed abnormal sperm morphologies, vacuoles in spermatogenic cells, cell dispersion, incomplete cell structures, and deformed nucleoli. These results indicated that MCLR could induce toxic effects on the reproductive system of frogs, significantly decrease testosterone content, and rapidly increase estradiol content. Prolonged exposure and increased concentration enhanced the relative expression levels of P450 aromatase and steroidogenic factor 1; thus, endocrine function in frogs was disrupted. This study is the first to demonstrate in vivo MCLR toxicity in the reproductive system of male R. nigromaculata. This study provided a scientific basis of the global decline in amphibian populations.

Endocrine-disrupting effects and reproductive toxicity of low dose MCLR on male frogs (Rana nigromaculata) in vivo

International Nuclear Information System (INIS)

Jia, Xiuying; Cai, Chenchen; Wang, Jia; Gao, Nana; Zhang, Hangjun

2014-01-01

Highlights: • Low-dose MCLR (1 μg/L) elicits a potential ecological effect on amphibian populations. • MCLR can induce abnormal sperm morphologies and activities on male frogs. • MCLR can induce a decrease in serum testosterone and an increase in serum estradiol of male frogs. • MCLR can increase SF-1 protein levels and decrease P450 aromatase levels in the gonads of frogs. - Abstract: Toxic cyanobacterial blooms are potential global threats to aquatic ecosystems and human health. The World Health Organization has set a provisional guideline limit of 1 μg/L microcystin-LR (MCLR) in freshwater. However, MCLR concentrations in several water bodies have exceeded this level. Despite this recommended human safety standard, MCLR-induced endocrine-disrupting effects and reproductive toxicity on male frog (Rana nigromaculata) were demonstrated in this study. Results showed that sperm motility and sperm count were significantly and negatively correlated with exposure time and concentration. By contrast, abnormal sperm rate was positively correlated with both parameters. Ultrastructural observation results revealed abnormal sperm morphologies, vacuoles in spermatogenic cells, cell dispersion, incomplete cell structures, and deformed nucleoli. These results indicated that MCLR could induce toxic effects on the reproductive system of frogs, significantly decrease testosterone content, and rapidly increase estradiol content. Prolonged exposure and increased concentration enhanced the relative expression levels of P450 aromatase and steroidogenic factor 1; thus, endocrine function in frogs was disrupted. This study is the first to demonstrate in vivo MCLR toxicity in the reproductive system of male R. nigromaculata. This study provided a scientific basis of the global decline in amphibian populations

Altered Immune Response of the Rice Frog Fejervarya limnocharis Living in Agricultural Area with Intensive Herbicide Utilization at Nan Province, Thailand

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Khattapan Jantawongsri

2015-01-01

Full Text Available Herbicides (atrazine, glyphosate and paraquat have been intensively used in Nan Province for a long time. Prior observations indicated that herbicide contamination and adverse health effects were found on the rice frog Fejervarya limnocharis living in paddy fields at Nan Province. Contamination of herbicides may influence disease emergence by acting directly or indirectly upon the immune system of amphibian or by causing disruptions in homeostasis, it is thus interesting to investigate potential effects of herbicide contamination in Nan Province on immune responses of the rice frog living in agricultural areas. Frogs were caught from a paddy field with no history of herbicide utilization (reference site and a paddy field with intensive herbicide utilization (contaminated site during 2010-2011. After dissection, frog livers were fixed in 10% neutral buffer formalin, processed by paraffin method and stained with hematoxylin and eosin. Number of melanomacrophage and melanomacrophage center (MMC were counted under a light microscope and used as markers of non-specific immune response. It was found that there was no significant sex-related difference in these numbers. However, there were significant seasonal differences in these numbers in both reference and contaminated site frogs, suggesting that seasonal difference in herbicide usage tend to affect frog's immune system in agricultural areas. Furthermore, numbers of melanomacrophage and MMC in early wet, late wet and early dry periods were markedly higher in the contaminated site frogs compared to those of the reference site frogs. The observation on amphibian's immune response to environmental contaminants could indicate the impacts of herbicide utilization on other vertebrates, as well as its role in amphibian declines.

Legacy of road salt: Apparent positive larval effects counteracted by negative postmetamorphic effects in wood frogs.

Science.gov (United States)

Dananay, Kacey L; Krynak, Katherine L; Krynak, Timothy J; Benard, Michael F

2015-10-01

Road salt runoff has potentially large effects on wetland communities, but is typically investigated in short-term laboratory trials. The authors investigated effects of road salt contamination on wood frogs (Rana sylvatica) by combining a field survey with 2 separate experiments. The field survey tested whether wood frog larval traits were associated with road salt contamination in natural wetlands. As conductivity increased, wood frog larvae were less abundant, but those found were larger. In the first experiment of the present study, the authors raised larvae in outdoor artificial ponds under 4 salt concentrations and measured larval vital rates, algal biomass, and zooplankton abundance. Salt significantly increased larval growth, algal biomass, and decreased zooplankton abundance. In the second experiment, the authors raised larvae to metamorphosis in the presence and absence of salt contamination and followed resulting juvenile frogs in terrestrial pens at high and low densities. Exposure to road salt as larvae caused juvenile frogs to have greater mortality in low-density terrestrial environments, possibly because of altered energy allocation, changes in behavior, or reduced immune defenses. The present study suggests that low concentrations of road salt can have positive effects on larval growth yet negative effects on juvenile survival. These results emphasize the importance of testing for effects of contaminants acting through food webs and across multiple life stages as well as the potential for population-level consequences in natural environments. © 2015 SETAC.

Persistence at distributional edges: Columbia spotted frog habitat in the arid Great Basin, USA.

Science.gov (United States)

Arkle, Robert S; Pilliod, David S

2015-09-01

A common challenge in the conservation of broadly distributed, yet imperiled species is understanding which factors facilitate persistence at distributional edges, locations where populations are often vulnerable to extirpation due to changes in climate, land use, or distributions of other species. For Columbia spotted frogs (Rana luteiventris) in the Great Basin (USA), a genetically distinct population segment of conservation concern, we approached this problem by examining (1) landscape-scale habitat availability and distribution, (2) water body-scale habitat associations, and (3) resource management-identified threats to persistence. We found that areas with perennial aquatic habitat and suitable climate are extremely limited in the southern portion of the species' range. Within these suitable areas, native and non-native predators (trout and American bullfrogs [Lithobates catesbeianus]) are widespread and may further limit habitat availability in upper- and lower-elevation areas, respectively. At the water body scale, spotted frog occupancy was associated with deeper sites containing abundant emergent vegetation and nontrout fish species. Streams with American beaver (Castor canadensis) frequently had these structural characteristics and were significantly more likely to be occupied than ponds, lakes, streams without beaver, or streams with inactive beaver ponds, highlighting the importance of active manipulation of stream environments by beaver. Native and non-native trout reduced the likelihood of spotted frog occupancy, especially where emergent vegetation cover was sparse. Intensive livestock grazing, low aquatic connectivity, and ephemeral hydroperiods were also negatively associated with spotted frog occupancy. We conclude that persistence of this species at the arid end of its range has been largely facilitated by habitat stability (i.e., permanent hydroperiod), connectivity, predator-free refugia, and a commensalistic interaction with an ecosystem

Effect of magnetic fields on green color formation in frog skin

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H. Kashiwagi

2017-05-01

Full Text Available The present work is focused on a dynamic and efficient optical control system that is made possible by investigation of the body surfaces of various animals. Specifically, we expect Japanese tree frog (Hyla japonica skin to provide a model for a flexible display device actuator mechanism. Tree frogs change body color from their original green to other colors in response to background colors. The color formation is controlled not only by chromatophores, but also by guanine microcrystals in iridophores. We collected sample microcrystals from the frog’s dorsal skin and made a model display sheet using the green skin layers. The transparent chamber that contained the crystal suspension was layered to enhance light reflection. Sheet color was observed while the angle of light incidence was varied, with and without magnetic field exposure at 0.3 T. A slight increase in red and green intensity was detected. Additionally, reflected intensity increased with increasing angle of incidence. These results indicate that the guanine crystal platelets in frog skin can efficiently switch the reflected light direction under application of a magnetic field. This in turn suggests that a several-micron-sized microcrystal of this type is a candidate material for development of flexible optical chips for ambient light control.

An addition to the diversity of dendrobatid frogs in Venezuela: description of three new collared frogs (Anura: Dendrobatidae: Mannophryne

Directory of Open Access Journals (Sweden)

César Luis Barrio-Amorós

2010-07-01

Full Text Available Three new species of collared frogs of the genus Mannophryne are described from Venezuela. Two are newly discovered taxa from the Venezuelan Andes, whereas the third species, previously confused with M. trinitatis, is from the Caracas area in the Cordillera de la Costa. The call of the three new species and that of Mannophryne collaris are described. Taxonomic, zoogeographic, and conservation issues are discussed.

Design and Dynamic Model of a Frog-inspired Swimming Robot Powered by Pneumatic Muscles

Science.gov (United States)

Fan, Ji-Zhuang; Zhang, Wei; Kong, Peng-Cheng; Cai, He-Gao; Liu, Gang-Feng

2017-09-01

Pneumatic muscles with similar characteristics to biological muscles have been widely used in robots, and thus are promising drivers for frog inspired robots. However, the application and nonlinearity of the pneumatic system limit the advance. On the basis of the swimming mechanism of the frog, a frog-inspired robot based on pneumatic muscles is developed. To realize the independent tasks by the robot, a pneumatic system with internal chambers, micro air pump, and valves is implemented. The micro pump is used to maintain the pressure difference between the source and exhaust chambers. The pneumatic muscles are controlled by high-speed switch valves which can reduce the robot cost, volume, and mass. A dynamic model of the pneumatic system is established for the simulation to estimate the system, including the chamber, muscle, and pneumatic circuit models. The robot design is verified by the robot swimming experiments and the dynamic model is verified through the experiments and simulations of the pneumatic system. The simulation results are compared to analyze the functions of the source pressure, internal volume of the muscle, and circuit flow rate which is proved the main factor that limits the response of muscle pressure. The proposed research provides the application of the pneumatic muscles in the frog inspired robot and the pneumatic model to study muscle controller.

[Biological testing of water with different structural states in rats and frogs].

Science.gov (United States)

Farashchuk, N F; Mikhaylova, R I; Telenkova, O G

2014-01-01

The effect of water samples with different structural states on some physiological indices of white laboratory rats, 5 groups of 10 animals (5 females and 5 males) and frogs has been studied. The investigation was performed for 1 month. For the determination of the content of liquid crystal associates (LCA) in water samples there was used the dilatometric method, the performance of experimental animals was studied by the swimming test (up to total fatigue). The performed experiment on growing rats with the use of water with varying degrees of structuredness showed that according to the weight gain there were optimal water "Lekor" and tap water, treated with Bioptron (the content of the structured fraction is 5.06 +/- 0.09% and 6.9 +/- 0.23%, respectively). On physical performance the best indices were in animals consumed water treated with the Bioptron lamp. In performance of experiments on frogs it was found that cardiac function in animals under experimental conditions over time weakens spontaneously: heart rate and cardiac output decline. Therefore, the effect of different water samples on the cardiac function was assessed on the intensity of its decrease for 15 minutes. In the experimental study of the effect of water with different content of LCA on heart rate and cardiac output of the frog it was found that the optimum level of structuredness of water is within the range of 5.06 +/- 0.09% (in water "Lekor") - 6.9 +/- 0.23% (tap water treated with Bioptron). All the other water samples, the content of nanocrystals in which was below or above this range, has a pronounced inhibitory effect on the heart performance of the frog.

The First Call Note Plays a Crucial Role in Frog Vocal Communication.

Science.gov (United States)

Yue, Xizi; Fan, Yanzhu; Xue, Fei; Brauth, Steven E; Tang, Yezhong; Fang, Guangzhan

2017-08-31

Vocal Communication plays a crucial role in survival and reproductive success in most amphibian species. Although amphibian communication sounds are often complex consisting of many temporal features, we know little about the biological significance of each temporal component. The present study examined the biological significance of notes of the male advertisement calls of the Emei music frog (Babina daunchina) using the optimized electroencephalogram (EEG) paradigm of mismatch negativity (MMN). Music frog calls generally contain four to six notes separated approximately by 150 millisecond intervals. A standard stimulus (white noise) and five deviant stimuli (five notes from one advertisement call) were played back to each subject while simultaneously recording multi-channel EEG signals. The results showed that the MMN amplitude for the first call note was significantly larger than for that of the others. Moreover, the MMN amplitudes evoked from the left forebrain and midbrain were typically larger than those from the right counterpart. These results are consistent with the ideas that the first call note conveys more information than the others for auditory recognition and that there is left-hemisphere dominance for processing information derived from conspecific calls in frogs.

Climatic influences on the breeding biology of the agile frog ( Rana dalmatina)

Science.gov (United States)

Combes, Magali; Pinaud, David; Barbraud, Christophe; Trotignon, Jacques; Brischoux, François

2018-02-01

Severe population declines of amphibians have been shown to be attributed to climate change. Nevertheless, the various mechanisms through which climate can influence population dynamics of amphibians remain to be assessed, notably to disentangle the relative synergetic or antagonistic influences of temperature and precipitations on specific life history stages. We investigated the impact of rainfall and temperature on the egg-clutch abundance in a population of agile frog ( Rana dalmatina) during 29 years (1987-2016) on 14 breeding sites located in Brenne Natural Park, France. Specifically, we examined the influence of environmental conditions occurring during five temporal windows of the year cycle corresponding to specific life history stages. Overall, our results suggest that the year-to-year fluctuations of egg-clutch abundances in Brenne Natural Park were partly dependent on local climatic conditions (rainfall and temperature). Climate seemed to influence breeding frogs during the autumn-winter period preceding reproduction. Spring and summer conditions did not influence reproduction. Additionally, we failed to detect effects of climatic conditions on newly metamorphosed individuals. Other factors such as density dependence and inter-specific interactions with introduced predators are likely to play a significant role in reproduction dynamics of the studied frog populations.

Evidence for a Na+/Ca2+ exchange mechanism in frog skin epithelium

DEFF Research Database (Denmark)

Madsen, K H; Brodin, Birger; Nielsen, R

1999-01-01

In the present study we investigated the possible existence of a Na+/Ca2+ exchange mechanism in the basolateral membrane of the frog skin epithelium and whether such a mechanism plays a role in the regulation of transepithelial Na+ transport. Cytosolic calcium ([Ca2+]i) was measured with the probe...... in serosal Na+ were followed by stepwise changes in [Ca2+]i. These observations indicate the existence of a Na+/Ca2+ exchange mechanism in the basolateral membrane of the frog skin epithelium. The transepithelial Na+ transport decreased from 13.2+/-1.8 to 9.2+/-1.5 microA cm-2 (n=8, P=0.049) when Na...

Tool path planning of hole-making operations in ejector plate of injection mould using modified shuffled frog leaping algorithm

Directory of Open Access Journals (Sweden)

Amol M. Dalavi

2016-07-01

Full Text Available Optimization of hole-making operations in manufacturing industry plays a vital role. Tool travel and tool switch planning are the two major issues in hole-making operations. Many industrial applications such as moulds, dies, engine block, automotive parts etc. requires machining of large number of holes. Large number of machining operations like drilling, enlargement or tapping/reaming are required to achieve the final size of individual hole, which gives rise to number of possible sequences to complete hole-making operations on the part depending upon the location of hole and tool sequence to be followed. It is necessary to find the optimal sequence of operations which minimizes the total processing cost of hole-making operations. In this work, therefore an attempt is made to reduce the total processing cost of hole-making operations by applying relatively new optimization algorithms known as shuffled frog leaping algorithm and proposed modified shuffled frog leaping algorithm for the determination of optimal sequence of hole-making operations. An industrial application example of ejector plate of injection mould is considered in this work to demonstrate the proposed approach. The obtained results by the shuffled frog leaping algorithm and proposed modified shuffled frog leaping algorithm are compared with each other. It is seen from the obtained results that the results of proposed modified shuffled frog leaping algorithm are superior to those obtained using shuffled frog leaping algorithm.

Dual-function vector for protein expression in both mammalian cells and Xenopus laevis oocytes

DEFF Research Database (Denmark)

Jespersen, Thomas; Grunnet, M; Angelo, K

2002-01-01

Both Xenopus laevis oocytes and mammalian cells are widely used for heterologous expression of several classes of proteins, and membrane proteins especially, such as ion channels or receptors, have been extensively investigated in both cell types. A full characterization of a specific protein wil...

METAMORPHIC INHIBITION OF XENOPUS LAEVIS BY SODIUM PERCHLORATE: EFFECTS ON DEVELOPMENT AND THYROID HISTOLOGY

Science.gov (United States)

The perchlorate anion inhibits thyroid hormone (TH) synthesis via inhibition of the sodium-iodide symporter. It is, therefore, a good model chemical to aid in the development of a bioassay to screen chemicals for effects on thyroid function. Xenopus laevis larvae were exposed to ...

Odorous and non-fatal skin secretion of adult wrinkled frog (Rana rugosa is effective in avoiding predation by snakes.

Directory of Open Access Journals (Sweden)

Yuri Yoshimura

Full Text Available The roles played by nonfatal secretions of adult anurans in the avoidance of predation remain unknown. The adult Wrinkled frog (Rana rugosa has warty skin with the odorous mucus secretion that is not fatal to the snake Elaphe quadrivirgata. We fed R. rugosa or Fejervarya limnocharis, which resembles R. rugosa in appearance and has mucus secretion, to snakes and compared the snakes' responses to the frogs. Compared to F. limnocharis, R. rugosa was less frequently bitten or swallowed by snakes. The snakes that bit R. rugosa spat out the frogs and showed mouth opening (gaping behavior, while the snakes that bit F. limnocharis did not show gaping behavior. We also compared the responses of the snakes to R. rugosa and F. limnocharis secretions. We coated palatable R. japonica with secretions from R. rugosa or F. limnocharis. The frogs coated by R. rugosa secretion were less frequently bitten or swallowed than those coated by F. limnocharis secretion. We concluded that compared to different frog species of similar sizes, the adult R. rugosa was less frequently preyed upon by, and that its skin secretion was effective in avoiding predation by snakes.

Odorous and non-fatal skin secretion of adult wrinkled frog (Rana rugosa) is effective in avoiding predation by snakes.

Science.gov (United States)

Yoshimura, Yuri; Kasuya, Eiiti

2013-01-01

The roles played by nonfatal secretions of adult anurans in the avoidance of predation remain unknown. The adult Wrinkled frog (Rana rugosa) has warty skin with the odorous mucus secretion that is not fatal to the snake Elaphe quadrivirgata. We fed R. rugosa or Fejervarya limnocharis, which resembles R. rugosa in appearance and has mucus secretion, to snakes and compared the snakes' responses to the frogs. Compared to F. limnocharis, R. rugosa was less frequently bitten or swallowed by snakes. The snakes that bit R. rugosa spat out the frogs and showed mouth opening (gaping) behavior, while the snakes that bit F. limnocharis did not show gaping behavior. We also compared the responses of the snakes to R. rugosa and F. limnocharis secretions. We coated palatable R. japonica with secretions from R. rugosa or F. limnocharis. The frogs coated by R. rugosa secretion were less frequently bitten or swallowed than those coated by F. limnocharis secretion. We concluded that compared to different frog species of similar sizes, the adult R. rugosa was less frequently preyed upon by, and that its skin secretion was effective in avoiding predation by snakes.

Importance of riparian remnants for frog species diversity in a highly fragmented rainforest.

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Rodríguez-Mendoza, Clara; Pineda, Eduardo

2010-12-23

Tropical forests undergo continuous transformation to other land uses, resulting in landscapes typified by forest fragments surrounded by anthropogenic habitats. Small forest fragments, specifically strip-shaped remnants flanking streams (referred to as riparian remnants), can be particularly important for the maintenance and conservation of biodiversity within highly fragmented forests. We compared frog species diversity between riparian remnants, other forest fragments and cattle pastures in a tropical landscape in Los Tuxtlas, Mexico. We found similar species richness in the three habitats studied and a similar assemblage structure between riparian remnants and forest fragments, although species composition differed by 50 per cent. Frog abundance was halved in riparian remnants compared with forest fragments, but was twice that found in pastures. Our results suggest that riparian remnants play an important role in maintaining a portion of frog species diversity in a highly fragmented forest, particularly during environmentally stressful (hot and dry) periods. In this regard, however, the role of riparian remnants is complementary, rather than substitutive, with respect to the function of other forest fragments within the fragmented forest.

Main alkaloids from the Brazilian dendrobatidae frog Epipedobates flavopictus: pumiliotoxin 251D, histrionicotoxin and decahydroquinolines.

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Mortari, Márcia Renata; Schwartz, Elisabeth N Ferroni; Schwartz, Carlos Alberto; Pires, Osmindo Rodrigues; Santos, Marcello Moreira; Bloch, Carlos; Sebben, Antonio

2004-03-01

Epipedobates flavopictus, Dendrobatidae, is a small aposematic frog found in Brazilian Cerrado bioma. In the present work, we isolated and characterized chemically the most abundant alkaloids present in the cutaneous extract of E. flavopictus. The specimens were collected in Pirenópolis (Goiás, Brazil), their skins were removed and extracted with methanol, and submitted to purification by HPLC and identification by gas chromatography and mass spectrometry. Pumiliotoxin 251D, histrionicotoxin 285Da and two decahydroquinolines, 219A and 243A, were identified. The pumiliotoxin 251D was tested on isolated frog sciatic nerve and on isolated guinea pig ileum muscle. The pumiliotoxin 251D slightly reduced the action potentials amplitude of frog sciatic nerve. The crude skin extract of E. flavopictus and the pumiliotoxin 251D produced rhythmic contractions and increased the muscular tension on isolated guinea pig ileum.

Development of a New Decision Tree to Rapidly Screen Chemical Estrogenic Activities of Xenopus laevis.

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Wang, Ting; Li, Weiying; Zheng, Xiaofeng; Lin, Zhifen; Kong, Deyang

2014-02-01

During the last past decades, there is an increasing number of studies about estrogenic activities of the environmental pollutants on amphibians and many determination methods have been proposed. However, these determination methods are time-consuming and expensive, and a rapid and simple method to screen and test the chemicals for estrogenic activities to amphibians is therefore imperative. Herein is proposed a new decision tree formulated not only with physicochemical parameters but also a biological parameter that was successfully used to screen estrogenic activities of the chemicals on amphibians. The biological parameter, CDOCKER interaction energy (Ebinding ) between chemicals and the target proteins was calculated based on the method of molecular docking, and it was used to revise the decision tree formulated by Hong only with physicochemical parameters for screening estrogenic activity of chemicals in rat. According to the correlation between Ebinding of rat and Xenopus laevis, a new decision tree for estrogenic activities in Xenopus laevis is finally proposed. Then it was validated by using the randomly 8 chemicals which can be frequently exposed to Xenopus laevis, and the agreement between the results from the new decision tree and the ones from experiments is generally satisfactory. Consequently, the new decision tree can be used to screen the estrogenic activities of the chemicals, and combinational use of the Ebinding and classical physicochemical parameters can greatly improves Hong's decision tree. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Columbia spotted frog (Rana luteiventris) in southeastern Oregon: A survey of historical localities, 2009

Science.gov (United States)

Pearl, Chistopher A.; Galvan, Stephanie K.; Adams, Michael J.; McCreary, Brome

2010-01-01

The Columbia spotted frog (Rana luteiventris) occupies a large range in western North America and is comprised of at least three genetic units. Concern exists regarding the status of the Great Basin populations in Oregon, Idaho, and Nevada. We surveyed target and nearby alternate sites on public lands in southeastern Oregon where there was evidence that Columbia spotted frogs were historically present. We found the species at 59.5 percent (25 of 42) of target or nearby alternate sites. They were in 15 of 23 permanent streams and 8 of 13 intermittent streams. Our surveys do not provide evidence of widespread population losses in our sites. Interpretation of status of Columbia spotted frogs in this study is limited by a lack of precision in some of the historical locations and by our inability to determine if locations where only adults were indicated in the historical record once had breeding populations. Our results support the need for continued investigation of these populations.

Effects of the herbicide imazapyr on juvenile Oregon spotted frogs

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Yahnke, Amy E.; Grue, Christian E.; Hayes, Marc P.; Troiano, Alexandra T.

2013-01-01

Conflict between native amphibians and aquatic weed management in the Pacific Northwest is rarely recognized because most native stillwater-breeding amphibian species move upland during summer, when herbicide application to control weeds in aquatic habitats typically occurs. However, aquatic weed management may pose a risk for aquatic species present in wetlands through the summer, such as the Oregon spotted frog (OSF, Rana pretiosa), a state endangered species in Washington. Acute toxicity of herbicides used to control aquatic weeds tends to be low, but the direct effects of herbicide tank mixes on OSFs have remained unexamined. We exposed juvenile OSFs to tank mixes of the herbicide imazapyr, a surfactant, and a marker dye in a 96-h static-renewal test. The tank mix was chosen because of its low toxicity to fish and its effectiveness in aquatic weed control. Concentrations were those associated with low-volume (3.5 L/ha) and high-volume (7.0 L/ha) applications of imazapyr and a clean-water control. Following exposure, frogs were reared for two months in clean water to identify potential latent effects on growth. Endpoints evaluated included feeding behavior, growth, and body and liver condition indices. We recorded no mortalities and found no significant differences for any end point between the herbicide-exposed and clean-water control frogs. The results suggest that imazapyr use in wetland restoration poses a low risk of direct toxic effects on juvenile OSFs.

Bioaccumulation of polychlorinated biphenyls in ranid frogs and northern water snakes from a hazardous waste site and a contaminated watershed.

Science.gov (United States)

Fontenot, L W; Noble, G P; Akins, J M; Stephens, M D; Cobb, G P

2000-04-01

Livers of bullfrogs (Rana catesbeiana) from a polychlorinated biphenyl (PCB) contaminated watershed and hazardous waste site located in Pickens County, South Carolina, contained significantly higher concentrations of PCBs (2.33 and 2.26 ppm, respectively) than those from a reference site (0.05 ppm). Green frogs (R. clamitans) from the two contaminated sites also accumulated higher levels of PCBs (2.37 and 3.88 ppm, respectively) than those from the reference site (0.02 ppm). No temporal variation was observed in PCB concentrations of bullfrogs or green frogs from the contaminated sites between 1992 and 1993. Levels of PCBs in the livers of northern water snakes (Nerodia sipedon) were significantly higher in snakes from the contaminated watershed (13.70 ppm) than in those from the waste site (2.29 ppm) and two reference sites (2.50 and 1.23 ppm). When compared to frogs, significantly higher bioaccumulation occurred in water snakes from the contaminated watershed. No significant differences in PCB levels were found with respect to sex or body size (snout-vent length (SVL) or body mass) for frogs or snakes. PCBs were detected also in eggs of both frogs and snakes. Results of this study provide baseline data and document the bioaccumulation of PCB residues in frog and snake tissues; however, the significance of these tissue residues to reproduction, survival, growth/development, and population dynamics in contaminated habitats is unknown.

Differential uptake of gold nanoparticles by 2 species of tadpole, the wood frog (Lithobates sylvaticus) and the bullfrog (Lithobates catesbeianus).

Science.gov (United States)

Thompson, Lucas B; Carfagno, Gerardo L F; Andresen, Kurt; Sitton, Andrea J; Bury, Taylor; Lee, Laura L; Lerner, Kevin T; Fong, Peter P

2017-12-01

Engineered nanoparticles are aquatic contaminants of emerging concern that exert ecotoxicological effects on a wide variety of organisms. We exposed cetyltrimethylammonium bromide-capped spherical gold nanoparticles to wood frog and bullfrog tadpoles with conspecifics and in combination with the other species continuously for 21 d, then measured uptake and localization of gold. Wood frog tadpoles alone and in combination with bullfrog tadpoles took up significantly more gold than bullfrogs. Bullfrog tadpoles in combination with wood frogs took up significantly more gold than controls. The rank order of weight-normalized gold uptake was wood frogs in combination > wood frogs alone > bullfrogs in combination > bullfrogs alone > controls. In all gold-exposed groups of tadpoles, gold was concentrated in the anterior region compared with the posterior region of the body. The concentration of gold nanoparticles in the anterior region of wood frogs both alone and in combination with bullfrogs was significantly higher than the corresponding posterior regions. We also measured depuration time of gold in wood frogs. After 21 d in a solution of gold nanoparticles, tadpoles lost >83% of internalized gold when placed in gold-free water for 5 d. After 10 d in gold-free water, tadpoles lost 94% of their gold. After 15 d, gold concentrations were below the level of detection. Our finding of differential uptake between closely related species living in similar habitats with overlapping geographical distributions argues against generalizing toxicological effects of nanoparticles for a large group of organisms based on measurements in only one species. Environ Toxicol Chem 2017;36:3351-3358. © 2017 SETAC. © 2017 SETAC.

Quantifying anuran microhabitat use to infer the potential for parasite transmission between invasive cane toads and two species of Australian native frogs.

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Lígia Pizzatto

Full Text Available Parasites that are carried by invasive species can infect native taxa, with devastating consequences. In Australia, invading cane toads (Rhinella marina carry lungworm parasites (Rhabdias pseudosphaerocephala that (based on previous laboratory studies can infect native treefrogs (Litoria caerulea and L. splendida. To assess the potential of parasite transmission from the invader to the native species (and from one infected native frog to another, we used surveys and radiotelemetry to quantify anuran microhabitat use, and proximity to other anurans, in two sites in tropical Australia. Unsurprisingly, treefrogs spent much of their time off the ground (especially by day, and in undisturbed forests but terrestrial activity was common at night (especially in anthropogenically modified habitats. Microhabitat overlap between cane toads and frogs was generally low, except at night in disturbed areas, whereas overlap between the two frog species was high. The situations of highest overlap, and hence with the greatest danger of parasite transmission, involve aggregations of frogs within crevices by day, and use of open ground by all three anuran species at night. Overall, microhabitat divergence between toads and frogs should reduce, but not eliminate, the transmission of lungworms from invasive toads to vulnerable native frogs.

Taxonomic variation in oviposition by tailed frogs (Aschaphus spp.).

Science.gov (United States)

Nancy E. Karraker; David S. Pilliod; Michael J. Adams; Evelyn L. Bull; Paul Stephen Corn; Lowell V. Diller; Linda A. Dupuis; Marc P. Hayes; Blake R. Hossack; Garth R. Hodgson; Erin J. Hyde; Kirk Lohman; Bradford R. Norman; Lisa M. Ollivier; Christopher A. Pearl; Charles R. Peterson

2006-01-01

Tailed frogs (Ascaphus spp.) oviposit in cryptic locations in streams of the Pacific Northwest and Rocky Mountains. This aspect of their life history has restricted our understanding of their reproductive ecology. The recent split of A. montanus in the Rocky Mountains from A. truei was based on molecular...

Biomimetic agent based modelling using male Frog calling behaviour as a case study

DEFF Research Database (Denmark)

Jørgensen, Søren V.; Demazeau, Yves; Christensen-Dalsgaard, Jakob

2014-01-01

by individuals to generate their observed population behaviour. A number of existing agent-modelling frameworks are considered, but none have the ability to handle large numbers of time-dependent event-generating agents; hence the construction of a new tool, RANA. The calling behaviour of the Puerto Rican Tree...... Frog, E. coqui, is implemented as a case study for the presentation and discussion of the tool, and results from this model are presented. RANA, in its present stage of development, is shown to be able to handle the problem of modelling calling frogs, and several fruitful extensions are proposed...

Peptidomic analysis of skin secretions supports separate species status for the tailed frogs, Ascaphus truei and Ascaphus montanus

Science.gov (United States)

Conlon, J.M.; Bevier, C.R.; Coquet, L.; Leprince, J.; Jouenne, T.; Vaudry, H.; Hossack, B.R.

2007-01-01

The tailed frog Ascaphus truei Stejneger, 1899 is the most primitive extant anuran and the sister taxon to the clade of all other living frogs. The species occupies two disjunct ranges in the Northwest region of North America: the Cascade Mountains and coastal area from British Columbia to Northern California, and an inland range in the northern Rocky Mountains and the Blue and Wallowa mountains. A previous study led to the isolation of eight peptides with antimicrobial activity (termed the ascaphins) from skin secretions of A. truei from the coastal range. The present study has used peptidomic analysis to identify the products of orthologous ascaphin genes in electrically-stimulated skin secretions from inland range specimens. Structural characterization of the peptides demonstrated that ascaphins from the inland range contained the following amino acid substitutions compared with orthologs from the coastal range frogs: ascaphin-1 (Ala12 → Glu), ascaphin-3 (Asp4 → Glu), ascaphin-4 (Ala19 → Ser), ascaphin-5 (Lys12 → Thr), and ascaphin-7 (Gly8 → Ser and Ser20 → Asn). Orthologs of ascaphins-2, -6, and -8 were not identified but a paralog of ascaphin-5, identical to ascaphin-5 from coastal range frogs, was found. The data support the claims, derived from analysis of the nucleotide sequences of mitochondrial genes, that the inland populations of the tailed frog should be recognized as a distinct species, the Rocky Mountain tailed frog Ascaphus montanus and that the divergence of the species from A. truei probably occurred in the late Miocene (approximately 10 Mya).

Cloning, embryonic expression, and functional characterization of two novel connexins from Xenopus laevis

NARCIS (Netherlands)

de Boer, Teun P.; Kok, Bart; Roël, Giulietta; van Veen, Toon A. B.; Destrée, Olivier H. J.; Rook, Martin B.; Vos, Marc A.; de Bakker, Jacques M. T.; van der Heyden, Marcel A. G.

2006-01-01

Vertebrate gap junctions are constituted of connexin (Cx) proteins. In Xenopus laevis, only seven different Cxs have been described so far. Here, we identify two new Cxs from X. laevis. Cx28.6 displays > 60% amino acid identity with human Cx25, Cx29 displays strong homology with mouse Cx26 and Cx30.

Evidence of auditory insensitivity to vocalization frequencies in two frogs

DEFF Research Database (Denmark)

Goutte, Sandra; Mason, Matthew J; Christensen-Dalsgaard, Jakob

2017-01-01

The emergence and maintenance of animal communication systems requires the co-evolution of signal and receiver. Frogs and toads rely heavily on acoustic communication for coordinating reproduction and typically have ears tuned to the dominant frequency of their vocalizations, allowing discriminat...

Foraging behaviour in tadpoles of the bronze frog Rana temporalis ...

Indian Academy of Sciences (India)

Unknown

The ability of bronze frog Rana temporalis tadpoles (pure or mixed parental lines) to ... less of whether they are siblings or non-siblings in a group, which correlates well with ..... Sutherland W J and Parker G A 1992 The relationship between.

Expression of LRRC8/VRAC Currents in Xenopus Oocytes: Advantages and Caveats.

Science.gov (United States)

Gaitán-Peñas, Héctor; Pusch, Michael; Estévez, Raúl

2018-03-02

Volume-regulated anion channels (VRACs) play a role in controlling cell volume by opening upon cell swelling. Apart from controlling cell volume, their function is important in many other physiological processes, such as transport of metabolites or drugs, and extracellular signal transduction. VRACs are formed by heteromers of the pannexin homologous protein LRRC8A (also named Swell1) with other LRRC8 members (B, C, D, and E). LRRC8 proteins are difficult to study, since they are expressed in all cells of our body, and the channel stoichiometry can be changed by overexpression, resulting in non-functional heteromers. Two different strategies have been developed to overcome this issue: complementation by transient transfection of LRRC8 genome-edited cell lines, and reconstitution in lipid bilayers. Alternatively, we have used Xenopus oocytes as a simple system to study LRRC8 proteins. Here, we have reviewed all previous experiments that have been performed with VRAC and LRRC8 proteins in Xenopus oocytes. We also discuss future strategies that may be used to perform structure-function analysis of the VRAC in oocytes and other systems, in order to understand its role in controlling multiple physiological functions.

Chiricahua leopard frog status in the Galiuro Mountains, Arizona, with a monitoring framework for the species' entire range

Science.gov (United States)

Lawrence L. C. Jones; Michael J. Sredl

2005-01-01

The Chiricahua leopard frog (Rana chiricahuensis) was historically widespread in suitable habitat throughout its range. Reports of recent population declines led to inventories of Chiricahua leopard frog localities. Surveys reported here establish a new baseline of occurrence in the Galiuros: only two of 21 historical localities were found to be...

Receptor-mediated endocytosis of lysozyme in renal proximal tubules of the frog Rana temporaria

Directory of Open Access Journals (Sweden)

E.V. Seliverstova

2015-04-01

Full Text Available The mechanism of protein reabsorption in the kidney of lower vertebrates remains insufficiently investigated in spite of raising interest to the amphibian and fish kidneys as a useful model for physiological and pathophysiological examinations. In the present study, we examined the renal tubular uptake and the internalization rote of lysozyme after its intravenous injection in the wintering frog Rana temporaria using immunohisto- and immunocytochemistry and specific markers for some endocytic compartments. The distinct expression of megalin and cubilin in the proximal tubule cells of lysozyme-injected frogs was revealed whereas kidney tissue of control animals showed no positive immunoreactivity. Lysozyme was detected in the apical endocytic compartment of the tubular cells and colocalized with clathrin 10 min after injection. After 20 min, lysozyme was located in the subapical compartment negative to clathrin (endosomes, and intracellular trafficking of lysozyme was coincided with the distribution of megalin and cubilin. However, internalized protein was retained in the endosomes and did not reach lysosomes within 30 min after treatment that may indicate the inhibition of intracellular trafficking in hibernating frogs. For the first time, we provided the evidence that lysozyme is filtered through the glomeruli and absorbed by receptor-mediated clathrin-dependent endocytosis in the frog proximal tubule cells. Thus, the protein uptake in the amphibian mesonephros is mediated by megalin and cubilin that confirms a critical role of endocytic receptors in the renal reabsorption of proteins in amphibians as in mammals.

Paxillin and embryonic PolyAdenylation Binding Protein (ePABP) engage to regulate androgen-dependent Xenopus laevis oocyte maturation - A model of kinase-dependent regulation of protein expression.

Science.gov (United States)

Miedlich, Susanne U; Taya, Manisha; Young, Melissa Rasar; Hammes, Stephen R

2017-06-15

Steroid-triggered Xenopus laevis oocyte maturation is an elegant physiologic model of nongenomic steroid signaling, as it proceeds completely independent of transcription. We previously demonstrated that androgens are the main physiologic stimulator of oocyte maturation in Xenopus oocytes, and that the adaptor protein paxillin plays a crucial role in mediating this process through a positive feedback loop in which paxillin first enhances Mos protein translation, ensued by Erk2 activation and Erk-dependent phosphorylation of paxillin on serine residues. Phosphoserine-paxillin then further augments Mos protein translation and downstream Erk2 activation, resulting in meiotic progression. We hypothesized that paxillin enhances Mos translation by interacting with embryonic PolyAdenylation Binding Protein (ePABP) on polyadenylated Mos mRNA. Knockdown of ePABP phenocopied paxillin knockdown, with reduced Mos protein expression, Erk2 and Cdk1 activation, as well as oocyte maturation. In both Xenopus oocytes and mammalian cells (HEK-293), paxillin and ePABP constitutively interacted. Testosterone (Xenopus) or EGF (HEK-293) augmented ePABP-paxillin binding, as well as ePABP binding to Mos mRNA (Xenopus), in an Erk-dependent fashion. Thus, ePABP and paxillin work together in an Erk-dependent fashion to enhance Mos protein translation and promote oocyte maturation. Copyright © 2017 Elsevier B.V. All rights reserved.

Frogs from the Leeward group, Venezuela and eastern Colombia

NARCIS (Netherlands)

Brongersma, L.D.

1948-01-01

The present notes deal with a small collection of frogs that was made by Dr. P. WAGENAAR HUMMELINCK during his visits to the islands of the Leeward Group, Venezuela and Eastern Colombia. I have included in this study the specimens of Pleurodema brachyops (Cope) already present in the Rijksmuseum van

Lipofection strategy for the study of Xenopus retinal development.

Science.gov (United States)

Ohnuma, Shin-ichi; Mann, Fanny; Boy, Sébastien; Perron, Muriel; Harris, William A

2002-12-01

The analysis of gene function during retinal development can be addressed by perturbing gene expression either by inhibition or by overexpression in desired regions and at defined stages of development. An in vivo lipofection strategy has been applied for stage-specific and region-specific expression of genes in Xenopus retina. Due to colipofection efficiency, this strategy enables us to study functional interaction of genes by lipofecting multiple expression constructs. This lipofection technique also allows us to transfect morpholino oligonucleotides into retinoblasts to block gene function. We present here various aspects of this technique, including recent improvements and modifications.

Deficient induction response in a Xenopus nucleocytoplasmic hybrid.

Directory of Open Access Journals (Sweden)

Patrick Narbonne

2011-11-01

Full Text Available Incompatibilities between the nucleus and the cytoplasm of sufficiently distant species result in developmental arrest of hybrid and nucleocytoplasmic hybrid (cybrid embryos. Several hypotheses have been proposed to explain their lethality, including problems in embryonic genome activation (EGA and/or nucleo-mitochondrial interactions. However, conclusive identification of the causes underlying developmental defects of cybrid embryos is still lacking. We show here that while over 80% of both Xenopus laevis and Xenopus (Silurana tropicalis same-species androgenetic haploids develop to the swimming tadpole stage, the androgenetic cybrids formed by the combination of X. laevis egg cytoplasm and X. tropicalis sperm nucleus invariably fail to gastrulate properly and never reach the swimming tadpole stage. In spite of this arrest, these cybrids show quantitatively normal EGA and energy levels at the stage where their initial gastrulation defects are manifested. The nucleocytoplasmic incompatibility between these two species instead results from a combination of factors, including a reduced emission of induction signal from the vegetal half, a decreased sensitivity of animal cells to induction signals, and differences in a key embryonic protein (Xbra concentration between the two species, together leading to inefficient induction and defective convergence-extension during gastrulation. Indeed, increased exposure to induction signals and/or Xbra signalling partially rescues the induction response in animal explants and whole cybrid embryos. Altogether, our study demonstrates that the egg cytoplasm of one species may not support the development promoted by the nucleus of another species, even if this nucleus does not interfere with the cytoplasmic/maternal functions of the egg, while the egg cytoplasm is also capable of activating the genome of that nucleus. Instead, our results provide evidence that inefficient signalling and differences in the

The Contribution of Prohibitin 1 to Prostate Cancer Chemoresistance

Science.gov (United States)

2015-10-01

dioleyloxy) propyl ]-N,N,N-trimethylammonium chloride ) to transfect human, rat, mouse, xenopus (frog) and drosophila cells with luciferase mRNA.31 The...self-assembly strategy leads to the synthesis of hybrid NPs with relatively small size (≤100 nm) and long circulation time (t1/2 ∼8 h). Smaller NPs...Materials and Methods Detailed materials and methods are provided in SI Appendix, SI Materials and Methods, including the synthesis of cationic lipid

Pathosphere.org: Pathogen Detection and Characterization Through a Web-based, Open-source Informatics Platform

Science.gov (United States)

2015-12-29

human), Homo sapiens chromosome (human), Mus_musculus ( rodent ), Sus scrofa (pig), mitochondrion genome, and Xenopus laevis (frog) . The taxonomy... Amazon Web Services. PLoS Comput Biol 2011, 7:e1002147. 10. Briese T, Paweska JT, McMullan LK, Hutchison SK, Street C, Palacios G, Khristova ML...human enterovirus C genotypes found in respiratory samples from Peru . J Gen Virol 2013, 94(Pt 1):120–7. 54. Jacob ST, Crozier I, Schieffelin JS

Choosing the safest route: frog orientation in an agricultural landscape

NARCIS (Netherlands)

Mazerolle, M.J.; Vos, C.C.

2006-01-01

Orientation is a key component to successful movements between habitats. We hypothesized that barren agricultural landscapes hinder the ability of frogs to orient and move between habitats. Specifically, we predicted that when presented with a choice between a short route through a hostile

Genomic Sequencing of Ranaviruses Isolated from Edible Frogs (Pelophylax esculentus)

DEFF Research Database (Denmark)

Ariel, Ellen; Subramaniam, Kuttichantran; Imnoi, Kamonchai

2017-01-01

Ranaviruses were isolated from wild edible frogs (Pelophylax esculentus) during epizootics in Denmark and Italy. Phylogenomic analyses revealed that these isolates are closely related and belong to a clade of ranaviruses that includes the Andrias davidianus ranavirus (ADRV), common midwife toad r...

Severe IgE-mediated anaphylaxis following consumption of fried frog legs: definition of alpha-parvalbumin as the allergen in cause.

Science.gov (United States)

Hilger, C; Grigioni, F; Thill, L; Mertens, L; Hentges, F

2002-11-01

IgE-mediated allergic reactions to bullfrog and edible frog have been reported. The implicated allergens have not been defined so far. The frog material and the patient's serum from a case of severe food-induced anaphylaxis were used to define the implicated allergen at the protein and DNA level. Immunoblotting techniques and N-terminal protein microsequencing were used to define the allergen recognized by the patient's serum. Back translation from the identified protein sequence was used to design degenerated primers to amplify the allergen's cDNA by polymerase chain reaction (PCR). We defined the nucleotide sequence of the allergen from the frog of Indonesian origin that was consumed by the patient, and the homologous cDNA from Rana esculenta. Protein microsequencing revealed that the implicated frog allergen belonged to the parvalbumin family. cDNAs coding for alpha- and beta-parvalbumin of R. esculenta and Rana species were cloned. Recombinant proteins were expressed in Escherichia coli. The patient's serum IgE antibodies recognized parvalbumin prepared from frog muscle and recombinant alpha-parvalbumin from R. species but not from R. esculenta. Recombinant beta-parvalbumin was not recognized by the IgE antibodies. This work defines at the protein and DNA levels alpha-parvalbumin as the allergen implicated in a case of IgE-mediated anaphylaxis to frog muscle. It also shows that a protein belonging to the parvalbumin family is implicated in type I allergies outside the fish species.

Expression and physiological regulation of BDNF receptors in the neuroendocrine melanotrope cell of Xenopus laevis

NARCIS (Netherlands)

Kidane, A.H.; van Dooren, S.H.; Roubos, E.W.; Jenks, B.G.

2007-01-01

Brain-derived neurotrophic factor (BDNF) and alpha-melanophore-stimulating hormone (alpha-MSH) are co-sequestered in secretory granules in melanotrope cells of the pituitary pars intermedia of the amphibian Xenopus laevis. alpha-MSH is responsible for pigment dispersion in dermal melanophores during

Fatal attraction: adaptations to prey on native frogs imperil snakes after invasion of toxic toads.

Science.gov (United States)

Hagman, Mattias; Phillips, Benjamin L; Shine, Richard

2009-08-07

Adaptations that enhance fitness in one situation can become liabilities if circumstances change. In tropical Australia, native snake species are vulnerable to the invasion of toxic cane toads. Death adders (Acanthophis praelongus) are ambush foragers that (i) attract vertebrate prey by caudal luring and (ii) handle anuran prey by killing the frog then waiting until the frog's chemical defences degrade before ingesting it. These tactics render death adders vulnerable to toxic cane toads (Bufo marinus), because toads elicit caudal luring more effectively than do native frogs, and are more readily attracted to the lure. Moreover, the strategy of delaying ingestion of a toad after the strike does not prevent fatal poisoning, because toad toxins (unlike those of native frogs) do not degrade shortly after the prey dies. In our laboratory and field trials, half of the death adders died after ingesting a toad, showing that the specialized predatory behaviours death adders use to capture and process prey render them vulnerable to this novel prey type. The toads' strong response to caudal luring also renders them less fit than native anurans (which largely ignored the lure): all toads bitten by adders died. Together, these results illustrate the dissonance in behavioural adaptations that can arise following the arrival of invasive species, and reveal the strong selection that occurs when mutually naive species first interact.

Accumulation of pesticides in pacific chorus frogs (Pseudacris regilla) from California's Sierra Nevada Mountains, USA

Science.gov (United States)

Smalling, Kelly L.; Fellers, Gary M.; Kleeman, Patrick M.; Kuivila, Kathryn

2013-01-01

Pesticides are receiving increasing attention as potential causes of amphibian declines, acting singly or in combination with other stressors, but limited information is available on the accumulation of current-use pesticides in tissue. The authors examined potential exposure and accumulation of currently used pesticides in pond-breeding frogs (Pseudacris regilla) collected from 7 high elevations sites in northern California. All sites sampled are located downwind of California's highly agricultural Central Valley and receive inputs of pesticides through precipitation and/or dry deposition. Whole frog tissue, water, and sediment were analyzed for more than 90 current-use pesticides and pesticide degradates using gas chromatography–mass spectrometry. Two fungicides, pyraclostrobin and tebuconazole, and one herbicide, simazine, were the most frequently detected pesticides in tissue samples. Median pesticide concentration ranged from 13 µg/kg to 235 µg/kg wet weight. Tebuconazole and pyraclostrobin were the only 2 compounds observed frequently in frog tissue and sediment. Significant spatial differences in tissue concentration were observed, which corresponded to pesticide use in the upwind counties. Data generated indicated that amphibians residing in remote locations are exposed to and capable of accumulating current-use pesticides. A comparison of P. regilla tissue concentrations with water and sediment data indicated that the frogs are accumulating pesticides and are potentially a more reliable indicator of exposure to this group of pesticides than either water or sediment.

Effects of oil sands waste water on the wood frog (rana sylvatica)

Energy Technology Data Exchange (ETDEWEB)

Hersikorn, B.; Smits, J.E. [Saskatchewan Univ., Regina, SK (Canada)

2007-07-01

The sustainability of various reclamation strategies can be determined by the growth and health of indigenous amphibians (Wood Frogs). This paper referred to the large quantities of tailings water that are generated by oil sand extraction activities. It presented the results of a study that was conducted in the spring and summer of 2006 and 2007 on reclaimed formation wetlands comprising tailings water. The objective was to understand the impact of these wetlands on native amphibians. Frogs were exposed to wetlands containing oil sands process affected water (OSPW) and reference water (no OSPW). Six experimental trenches were made at one site in the first year. Each trench had 3 enclosures with 50 tadpoles. In the second year, there were 13 sites, including 6 reference and 7 OSPW affected sites, which were classified as old (more than 8 yrs) or young (less than 7 yrs). Four enclosures, with 50 tadpoles each, were placed in each wetland. The study involved the evaluation of growth rate, survival, time to metamorphosis, thyroid hormone concentrations, liver EROD activity, and tissue retinol concentrations. In addition, stable isotopes were used to track carbon flow from primary production plants, through the food chain, to tadpoles and frogs which represent intermediate and higher trophic levels in reclaimed wetlands.

Calcium regulation in frog peripheral nerve by the blood-nerve barrier

International Nuclear Information System (INIS)

Wadhwani, K.C.

1986-01-01

The objectives of this research were: (a) to investigate the characteristics of calcium transport across the perineurium and the endoneurial capillaries, and (b) to gain a better understanding of the extent of calcium homeostasis in the endoneurial space. To study the nature of calcium transport across the perineurium, the flux of radiotracer 45 Ca was measured through the perineurial cylinder, isolated from the frog sciatic nerve, and through the perineurium into the nerve in situ. To study the nature of calcium transport across the endoneurial capillaries, the permeability-surface area product (PA) of 45 Ca was determined as a function of the calcium concentration in the blood. To study calcium homeostasis, the calcium content of the frog sciatic nerve was determined as a function of chronic changes in plasma [Ca

Measurement and Evaluation of Wear Frogs Switches ŽSR

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Urda Ján

2014-05-01

Full Text Available This paper deals with the measurement and evaluation of wear frogs switches ZSR. One of the main problems is the oversize wear. The possibilities analysis of this problem is offered through a set of switches and monitoring of selected parameters. One of these parameters is also monitoring the vertical wear

Effects of X-irradiation on some aspects of protein metabolism in the frog, Rana hexadactyla

International Nuclear Information System (INIS)

Rajarami Reddy, G.; Sasira Babu, K.

1980-01-01

Changes in the level of total proteins and protease in brain, muscle and liver tissues of normal and X-irradiated frogs were determined. Low doses of radiation produced an increment in protein level while high doses produced decrement. However, protease activity at all doses exhibited an elevatory trend. Exposure of frogs to lethal doses resulted in increased protease activity and decreased protein content during post-irradiation periods. The results are discussed on the basis of protein destruction and lysosomal damage. (auth.)

Minimal health impacts but detectable tissue residues after exposure of northern leopard frogs (Lithobates pipiens) to commercial naphthenic acids

International Nuclear Information System (INIS)

Hersikorn, B.; Young, R.; Fedorak, P.; Smits, J.

2010-01-01

This presentation reported on a study that examined whether naphthenic acids (NAs) are a toxic component in oil sands process-affected materials (OSPM). The study investigated the toxicity of commercial (Refined Merichem) NAs to native amphibians (northern leopard frogs) exposed to saline conditions comparable to those of reclaimed wetlands on oil sand leases. Gas chromatography-mass spectroscopy analysis showed that the exposure of frogs to NAs solutions for 28 days resulted in proportional NA concentrations in extracts of frog muscle tissue. Biological assays were performed to determine if the increasing exposure to NAs caused a proportional compromise in the health of test animals. The innate immune function, thyroid hormones, and hepatic detoxification enzyme induction did not differ in response to increased tissue concentrations of NAs. The commercial NAs were absorbed and deposited in muscle tissue. It was concluded that NAs play only a small, if any, role in the toxicity of OSPM to frogs.

Ontogenetic polychromatism in marsupial frogs (Anura: Hylidae Ontogenetic polychromatism in marsupial frogs (Anura: Hylidae

Directory of Open Access Journals (Sweden)

Duellman William E.

1986-12-01

Full Text Available Color polymorphism is common in many species of marsupial frogs.  Extreme cases of pattern polymorphism are documented in four species. In Amphignathodon guentheri, Castrotheca aureomaculata, G. qriswoldi, and G. helenae juveniles are known to have only one color morph, where as two or more patterns exist in adults. In these species, polymorphism apparently develops ontogenetically. El polimorfismo cromático es común a algunas especies de sapos marsupiales. Casos extremos del modelo de polimorfismo son evidentes en cuatro especies Amphignathodon guentheri, Gastrotheca aureomaculata, G. griswoldi, y G. helenae. En estas especies, se sabe que los juveniles tienen sólo un morfo de color; el polimorfismo, al parecer, se desarrolla ontogenéticamente.

Allozyme comparison of three Trypanosoma species (Kinetoplastida: Trypanosomatidae) of toads and frogs by starch-gel electrophoresis.

Science.gov (United States)

Martin, D S; Desser, S S; Hong, H

1992-04-01

Six metabolic enzymes, glucose-6-phosphate dehydrogenase, glucosephosphate isomerase, isocitrate dehydrogenase, malate dehydrogenase, phosphoglucomutase, and purine nucleoside phosphorylase, from clonal isolates of 3 presumptive species of Trypanosoma (T. fallisi, T. ranarum, and T. rotatorium) from 3 anuran hosts (Bufo americanus, Rana clamitans, and Rana catesbeiana) were compared using starch-gel electrophoresis. Although bands were shared among the different zymodemes of isolates of the same host genus, low genetic polymorphism of the enzyme loci was observed with few apparent shared bands between samples isolated from frogs and toads. A distance value calculated between toad and frog trypanosome isolates suggests the likelihood of long-time separation of species. Cluster analysis based on overall similarity distinguished the trypanosomes of toads and frogs as separate taxa, suggesting that host specificity and observed morphological differences are consistent with heritable allozyme differences.

Diversity and biogeography of frogs in the genus Amnirana (Anura: Ranidae) across sub-Saharan Africa.

Science.gov (United States)

Jongsma, Gregory F M; Barej, Michael F; Barratt, Christopher D; Burger, Marius; Conradie, Werner; Ernst, Raffael; Greenbaum, Eli; Hirschfeld, Mareike; Leaché, Adam D; Penner, Johannes; Portik, Daniel M; Zassi-Boulou, Ange-Ghislain; Rödel, Mark-Oliver; Blackburn, David C

2018-03-01

Frogs in the genus Amnirana (family Ranidae) are widely distributed across sub-Saharan Africa and present a model system for exploring the relationship between diversification and geography across the continent. Using multiple loci from the mitochondrial (16S) and nuclear genomes (DISP2, FICD, KIAA2013, REV3L), we generated a strongly supported species-level phylogeny that provides insights into the continental biogeography of African species of Amnirana, which form a monophyletic group within the genus. Species delimitation analyses suggest that there may be as many as seven additional species of Amnirana in Africa. The biogeographic history of Amnirana is marked by several dispersal and vicariance events, including dispersal from the Lower Guinean Forest into the Congo Basin. In addition, phylogeographic patterns within two widespread species, A. albolabris and A. galamensis, reveal undescribed cryptic diversity. Populations assigned to A. albolabris in western Africa are more closely related to A. fonensis and require recognition as a distinct species. Our analyses reveal that the Lower and Upper Guinean Forest regions served as important centers of interspecific and intraspecific diversifications for Amnirana. Copyright © 2017 Elsevier Inc. All rights reserved.

Selection on MHC class II supertypes in the New Zealand endemic Hochstetter's frog.

Science.gov (United States)

Lillie, Mette; Grueber, Catherine E; Sutton, Jolene T; Howitt, Robyn; Bishop, Phillip J; Gleeson, Dianne; Belov, Katherine

2015-04-13

The New Zealand native frogs, family Leiopelmatidae, are among the most archaic in the world. Leiopelma hochstetteri (Hochstetter's frog) is a small, semi-aquatic frog with numerous, fragmented populations scattered across New Zealand's North Island. We characterized a major histocompatibility complex (MHC) class II B gene (DAB) in L. hochstetteri from a spleen transcriptome, and then compared its diversity to neutral microsatellite markers to assess the adaptive genetic diversity of five populations ("evolutionarily significant units", ESUs). L. hochstetteri possessed very high MHC diversity, with 74 DAB alleles characterized. Extremely high differentiation was observed at the DAB locus, with only two alleles shared between populations, a pattern that was not reflected in the microsatellites. Clustering analysis on putative peptide binding residues of the DAB alleles indicated four functional supertypes, all of which were represented in 4 of 5 populations, albeit at different frequencies. Otawa was an exception to these observations, with only two DAB alleles present. This study of MHC diversity highlights extreme population differentiation at this functional locus. Supertype differentiation was high among populations, suggesting spatial and/or temporal variation in selection pressures. Low DAB diversity in Otawa may limit this population's adaptive potential to future pathogenic challenges.

Effects of mosquitofish (Gambusia affinis cues on wood frog (Lithobates sylvaticus tadpole activity

Directory of Open Access Journals (Sweden)

Katherine F. Buttermore

2011-06-01

Full Text Available We examined the changes in activity of wood frog (Lithobates sylvaticus tadpoles exposed to combinations of visual, chemical, and mechanical cues of the invasive mosquitofish (Gambusia affinis. We also examined whether the responses of the tadpoles to the predator cues were influenced by the short-term accumulation of chemical cues in the experimental container. In our experiment, the activity of wood frog (L. sylvaticus tadpoles was not affected by the presence of various cues from mosquitofish. Our experiment demonstrated that the repeated use of trial water can influence the activity level of tadpoles, regardless of the predator cue treatment used. Tadpoles in the first trial tended to be less active than tadpoles in subsequent trials. This effect does not appear to be mediated by the accumulation of predator cues since there was no significant interaction term. Our results suggest that short-term accumulation of predator chemical cues do not affect the behavior of wood frog tadpoles: however, our results suggest that the repeated use of the same water in consecutive trials may affect tadpole behavior, perhaps through the accumulation of conspecific chemical cues.

Comparative effects of DDT, allethrin, dieldrin and aldrin-transdiol on sense organs of Xenopus laevis

NARCIS (Netherlands)

Akkermans, L.M.A.; Bercken, J. van den; Versluijs-Helder, M.

1975-01-01

The effects of DDT, allethrin, dieldrin and aldrin-transdiol were studied in two different sense organs of Xenopus laevis; the lateral-line organ and the cutaneous touch receptors. DDT and allethrin produced pronounced repetitive firing in both preparations. Dieldrin and aldrin-transdiol, on the

INTRAOCULAR PRESSURE AND EXAMINATION FINDINGS IN THREE SPECIES OF CENTRAL AND SOUTH AMERICAN TREE FROGS (CRUZIOHYLA CRASPEDOPUS, CRUZIOHYLA CALCARIFER, AND ANOTHECA SPINOSA).

Science.gov (United States)

Lewin, Andrew C; Hausmann, Jennifer C; Miller, Paul E

2017-09-01

The purpose of this prospective study was to describe intraocular pressure (IOP) and examination findings in three tree frog species (Cruziohyla craspedopus [fringe leaf frog], Cruziohyla calcarifer [splendid leaf frog], and Anotheca spinosa [spiny-headed or coronated tree frog]). Thirty-one C. craspedopus, four C. calcarifer, and five A. spinosa were weighed, sexed based on phenotype where possible, and examined using slit-lamp biomicroscopy and indirect ophthalmoscopy. IOP was measured using the TonoVet and TonoLab rebound tonometers while the frogs were held two ways (unrestrained, then restrained). Statistical differences were determined using one-way analysis of variance (ANOVA) and t-tests. Mean ± SD IOP (TonoVet and TonoLab, respectively) was 15.1 ± 2.5 mmHg and 15.6 ± 4.1 mmHg in C. craspedopus; 14.8 ± 1.5 mmHg and 18.8 ± 3.1 mmHg in C. calcarifer; and 9.1 ± 2.1 mmHg and 10.8 ± 1.4 mmHg in A. spinosa. There was no significant difference in IOP in C. craspedopus by eye (Right vs Left), tonometer, or restraint method. IOP in female C. craspedopus was 1-3 mm Hg higher than in males with both devices (P Cruziohyla genus frogs and A. spinosa for the TonoVet (P < 0.05). There was no difference in IOP measurements between the TonoVet and TonoLab in C. craspedopus. IOP varied by gender in C. craspedopus and between species, but not by tonometer. Ocular abnormalities were minimal in this group of captive bred frogs.

Identification of Gender-specific Transcripts by Microarray in Gonad Tissue of Larval and Juvenile Xenopus tropicalis

Science.gov (United States)

Amphibian model species Xenopus tropicalis is currently being utilized by EPA in the development of a standardized in vivo reproductive toxicity assay. Perturbations to the hypothalamic-pituitary-gonadal axis from exposure to endocrine disrupting compounds during larval develop...

Optimal inverse magnetorheological damper modeling using shuffled frog-leaping algorithm–based adaptive neuro-fuzzy inference system approach

Directory of Open Access Journals (Sweden)

Xiufang Lin

2016-08-01

Full Text Available Magnetorheological dampers have become prominent semi-active control devices for vibration mitigation of structures which are subjected to severe loads. However, the damping force cannot be controlled directly due to the inherent nonlinear characteristics of the magnetorheological dampers. Therefore, for fully exploiting the capabilities of the magnetorheological dampers, one of the challenging aspects is to develop an accurate inverse model which can appropriately predict the input voltage to control the damping force. In this article, a hybrid modeling strategy combining shuffled frog-leaping algorithm and adaptive-network-based fuzzy inference system is proposed to model the inverse dynamic characteristics of the magnetorheological dampers for improving the modeling accuracy. The shuffled frog-leaping algorithm is employed to optimize the premise parameters of the adaptive-network-based fuzzy inference system while the consequent parameters are tuned by a least square estimation method, here known as shuffled frog-leaping algorithm-based adaptive-network-based fuzzy inference system approach. To evaluate the effectiveness of the proposed approach, the inverse modeling results based on the shuffled frog-leaping algorithm-based adaptive-network-based fuzzy inference system approach are compared with those based on the adaptive-network-based fuzzy inference system and genetic algorithm–based adaptive-network-based fuzzy inference system approaches. Analysis of variance test is carried out to statistically compare the performance of the proposed methods and the results demonstrate that the shuffled frog-leaping algorithm-based adaptive-network-based fuzzy inference system strategy outperforms the other two methods in terms of modeling (training accuracy and checking accuracy.

Viability of Vibrio cholerae 01 on frog legs under frozen and refrigerated conditions and low dose radiation treatment

International Nuclear Information System (INIS)

Sang, F.C.; Hugh-Jones, M.E.; Hagstad, H.V.

1987-01-01

Frog legs were contaminated with Vibrio cholerae 01, Inaba serotype, EITor biotype. The organism remained viable for more than 28 and 2 d when stored at -20°C and 4°C, respectively. Exposure to a multicuries 60 Cobalt source of 50 and 100 kilorads eliminated V. cholerae from both the frozen and fresh frog legs

The odds of duplicate gene persistence after polyploidization

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Chain Frédéric JJ

2011-12-01

Full Text Available Abstract Background Gene duplication is an important biological phenomenon associated with genomic redundancy, degeneration, specialization, innovation, and speciation. After duplication, both copies continue functioning when natural selection favors duplicated protein function or expression, or when mutations make them functionally distinct before one copy is silenced. Results Here we quantify the degree to which genetic parameters related to gene expression, molecular evolution, and gene structure in a diploid frog - Silurana tropicalis - influence the odds of functional persistence of orthologous duplicate genes in a closely related tetraploid species - Xenopus laevis. Using public databases and 454 pyrosequencing, we obtained genetic and expression data from S. tropicalis orthologs of 3,387 X. laevis paralogs and 4,746 X. laevis singletons - the most comprehensive dataset for African clawed frogs yet analyzed. Using logistic regression, we demonstrate that the most important predictors of the odds of duplicate gene persistence in the tetraploid species are the total gene expression level and evenness of expression across tissues and development in the diploid species. Slow protein evolution and information density (fewer exons, shorter introns in the diploid are also positively correlated with duplicate gene persistence in the tetraploid. Conclusions Our findings suggest that a combination of factors contribute to duplicate gene persistence following whole genome duplication, but that the total expression level and evenness of expression across tissues and through development before duplication are most important. We speculate that these parameters are useful predictors of duplicate gene longevity after whole genome duplication in other taxa.

The metamorphosis of amphibian toxicogenomics

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Caren eHelbing

2012-03-01

Full Text Available Amphibians are important vertebrates in toxicology often representing both aquatic and terrestrial forms within the life history of the same species. Of the thousands of species, only two have substantial genomics resources: the recently published genome of the Pipid, Xenopus (Silurana tropicalis, and transcript information (and ongoing genome sequencing project of Xenopus laevis. However, many more species representative of regional ecological niches and life strategies are used in toxicology worldwide. Since Xenopus species diverged from the most populous frog family, the Ranidae, ~200 million years ago, there are notable differences between them and the even more distant Caudates (salamanders and Caecilians. These differences include genome size, gene composition, and extent of polyploidization. Application of toxicogenomics to amphibians requires the mobilization of resources and expertise to develop de novo sequence assemblies and analysis strategies for a broader range of amphibian species. The present mini-review will present the advances in toxicogenomics as pertains to amphibians with particular emphasis upon the development and use of genomic techniques (inclusive of transcriptomics, proteomics, and metabolomics and the challenges inherent therein.

LOCALIZATION OF PERMEABILITY BARRIERS IN THE FROG SKIN EPITHELIUM

Science.gov (United States)

Martinez-Palomo, A.; Erlij, D.; Bracho, H.

1971-01-01

Ruthenium red and colloidal lanthanum were used to determine the site of the structural barriers to diffusion within the intercellular spaces of frog skin epithelium. Electron micrographs show that occluding zonules located at the outer border of the stratum corneum and at the outer layer of the stratum granulosum are true tight junctions since they are impermeable to these tracers. Measurement of 140La uptake by the living skin shows that lanthanum moves across the external surface of the skin readily, into and out of a compartment that has a limited capacity and is bounded on its internal side by a barrier impermeable to lanthanum. Examination of these skins with the electron microscope suggests that the compartment is localized between the external membrane of the cells at the outer layer of the s. granulosum and at the outermost surface of the skin. These observations and other findings described in the literature indicate that the site of the external high resistance barrier of the frog skin is localized at the outer border of the s. granulosum. PMID:4329611

Wet adhesion with application to tree frog adhesive toe pads and tires

International Nuclear Information System (INIS)

Persson, B N J

2007-01-01

Strong adhesion between solids with rough surfaces is only possible if at least one of the solids is elastically very soft. Some lizards and spiders are able to adhere (dry adhesion) and move on very rough vertical surfaces due to very compliant surface layers on their attachment pads. Flies, bugs, grasshoppers and tree frogs have less compliant pad surface layers, and in these cases adhesion to rough surfaces is only possible because the animals inject a wetting liquid into the pad-substrate contact area, which generates a relative long-range attractive interaction due to the formation of capillary bridges. In this presentation I will discuss some aspects of wet adhesion for tree frogs and give some comments related to tire applications

Wet adhesion with application to tree frog adhesive toe pads and tires

Energy Technology Data Exchange (ETDEWEB)

Persson, B N J [IFF, FZ-Juelich, 52425 Juelich (Germany)

2007-09-19

Strong adhesion between solids with rough surfaces is only possible if at least one of the solids is elastically very soft. Some lizards and spiders are able to adhere (dry adhesion) and move on very rough vertical surfaces due to very compliant surface layers on their attachment pads. Flies, bugs, grasshoppers and tree frogs have less compliant pad surface layers, and in these cases adhesion to rough surfaces is only possible because the animals inject a wetting liquid into the pad-substrate contact area, which generates a relative long-range attractive interaction due to the formation of capillary bridges. In this presentation I will discuss some aspects of wet adhesion for tree frogs and give some comments related to tire applications.

Histamine H1 receptors are expressed in mouse and frog semicircular canal sensory epithelia.

Science.gov (United States)

Botta, Laura; Tritto, Simona; Perin, Paola; Laforenza, Umberto; Gastaldi, Giulia; Zampini, Valeria; Zucca, Gianpiero; Valli, Stefano; Masetto, Sergio; Valli, Paolo

2008-03-05

Histamine-related drugs are commonly used in the treatment of vertigo and related vestibular disorders. Their site and mechanism of action, however, are still poorly understood. To increase our knowledge of the histaminergic system in the vestibular organs, we have investigated the expression of H1 and H3 histamine receptors in the frog and mouse semicircular canal sensory epithelia. Analysis was performed by mRNA reverse transcriptase-PCR, immunoblotting and immunocytochemistry experiments. Our data show that both frog and mouse vestibular epithelia express H1 receptors. Conversely no clear evidence for H3 receptors expression was found.

Lateral mobility of plasma membrane lipids in Xenopus eggs: Regional differences related to animal/vegetal polarity

NARCIS (Netherlands)

Laat, S.W. de; Bluemink, J.G.; Dictus, W.J.A.G.; Zoelen, E.J.J. van; Tetteroo, P.A.T.; Tertoolen, L.G.J.

1984-01-01

Regional differences in the lateral mobility properties of plasma membrane lipids were studied in unfertilized and fertilized Xenopus eggs by fluorescence photobleaching recovery (FPR) measurements. Out of a variety of commonly used lipid probes only the aminofluorescein- -1abelled fatty

Probing the biology of cell boundary conditions through confinement of Xenopus cell-free cytoplasmic extracts.

Science.gov (United States)

Bermudez, Jessica G; Chen, Hui; Einstein, Lily C; Good, Matthew C

2017-01-01

Cell-free cytoplasmic extracts prepared from Xenopus eggs and embryos have for decades provided a biochemical system with which to interrogate complex cell biological processes in vitro. Recently, the application of microfabrication and microfluidic strategies in biology has narrowed the gap between in vitro and in vivo studies by enabling formation of cell-size compartments containing functional cytoplasm. These approaches provide numerous advantages over traditional biochemical experiments performed in a test tube. Most notably, the cell-free cytoplasm is confined using a two- or three-dimensional boundary, which mimics the natural configuration of a cell. This strategy enables characterization of the spatial organization of a cell, and the role that boundaries play in regulating intracellular assembly and function. In this review, we describe the marriage of Xenopus cell-free cytoplasm and confinement technologies to generate synthetic cell-like systems, the recent biological insights they have enabled, and the promise they hold for future scientific discovery. © 2017 Wiley Periodicals, Inc.

Anfíbios Anuros do Distrito Federal The Frogs of the Federal District of Brazil

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Bertha Lutz

1954-03-01

Full Text Available The frogs of the Federal District of Brazil are listed and discussed as to habit, biology and ecology. The F. D is situated 22° 54' 24" S. & 43° 10' 21" W Gr. and comprises 1.356 km². Its topography includes sea-shore, maritime scrub, lagoons, plains and marsh, open slopes, forested mountains and great heads of rock. Three thousand feet of altitude are attained at two points. Fifty two different frogs occur in the F.D. Three fifths of them live in open country. Two fifths of these have never been found above the plains; the others range higher but mostly in open country. Their environment offers conditions suitable for average tadpoles and adults. these frogs are more or less unspecialized. There are six genera and thirty species. Two thirds of the latter belong to the type genera of the large neotropical families Bufonidae, Leptodactylidae and Hylidae. Only in the maritime scrub formation are conditions somewhat different. Water for average tadpoles is provided by the lagoons. The xerophytism of the vegetation is, however, so marked that bromeliads growing on the ground provide almost the only appropriate shelter for adult tree-frogs used to sleeping upright on the vegetation. One large Hylid genus lives entirely in them. It is casque-headed and phragmotic, shutting the lumen of the leaf-cup with head used as a plug. Another large Hylid genus shows a lesser degree of the same specialization. (Lutz A & Lutz B, 1939 II. One genus with two species is entirely saxicolous; it lives on wet ledges of rock at all phases of its life history. (B. Lutz 1948. The other two fifths of the frogs from F. D. are montane forest forms. Their environment offers numerous and varied biotopes and is near optimum for adults. There is,however, hardly any standing water available for larvae. These frogs are ecologically diversified. They also show a general trend towards spawning in the adult biotipe, which leads to delayed hatching, semi-aquatic and terrestrial

The effects of four arthropod diets on the body and organ weights of the leopard frog, Rana pipiens, during vitellogenesis.

Science.gov (United States)

Lehman, G C

1978-12-01

Wild-caught adult Rana pipiens females were captured in midsummer and fed diets of crickets, flies sowbugs or wax moth larvae during a three-month period of active vitellogenesis. The cricket diet supported the most extensive body weight gain during this time and promoted a prolonged period of weight increase in an additional long-term study. Synchronous growth of the oocytes occurred in all four groups, but the ovaries and oviducts of cricket-fed animals were significantly larger than those of frogs on the other three diets. The significantly higher liver weights of frogs fed wax moth larvae may have reflected an augmentation of hepatic energy stores. Fat body weights were also highest in this group of animals. Frogs fed crickets and wax moth larvae possessed larger fat bodies than did the midsummer control animals killed immediately after their arrival in the laboratory. In contrast, frogs fed flies and sowbugs had smaller fat bodies than did the initial controls, suggesting that animals on these diets had utilized fat body lipid during vitellogenesis. Gastrocnemius and final body weights were lowest in frogs fed wax moth larvae. These findings may have reflected the nutritional content of the diet or the reduction in appetite frequently noted in these animals during observations of feeding behavior.

Roles of ADAM13-regulated Wnt activity in early Xenopus eye development

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Wei, Shuo; Xu, Guofeng; Bridges, Lance C.; Williams, Phoebe; Nakayama, Takuya; Shah, Anoop; Grainger, Robert M.; White, Judith M.; DeSimone, Douglas W.

2012-01-01

Pericellular proteolysis by ADAM family metalloproteinases has been widely implicated in cell signaling and development. We recently found that Xenopus ADAM13, an ADAM metalloproteinase, is required for activation of canonical Wnt signaling during cranial neural crest (CNC) induction by regulating a novel crosstalk between Wnt and ephrin B (EfnB) signaling pathways (Wei et al., 2010b). In the present study we show that the metalloproteinase activity of ADAM13 also plays important roles in eye development in X. tropicalis. Knockdown of ADAM13 results in reduced expression of eye field markers pax6 and rx1, as well as that of the pan-neural marker sox2. Activation of canonical Wnt signaling or inhibition of forward EfnB signaling rescues the eye defects caused by loss of ADAM13, suggesting that ADAM13 functions through regulation of the EfnB-Wnt pathway interaction. Downstream of Wnt, the head inducer Cerberus was identified as an effector that mediates ADAM13 function in early eye field formation. Furthermore, ectopic expression of the Wnt target gene snail2 restores cerberus expression and rescues the eye defects caused by ADAM13 knockdown. Together these data suggest an important role of ADAM13-regulated Wnt activity in eye development in Xenopus. PMID:22227340

Movement ecology and seasonal distribution of mountain yellow-legged frogs, Rana muscosa, in a high-elevation Sierra Nevada basin.

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K.L. Pope; K.R. Matthews

2001-01-01

Movement ecology and seasonal distribution of mountain yellow-legged frogs (Rana muscosa) in Dusy Basin (3470 m), Kings Canyon National Park, California, were characterized using passive integrated transponder (PIT) surveys and visual encounter surveys. We individually PIT-tagged 500 frogs during the summers of 1997 and 1998 and monitored these individuals during seven...

Fox (forkhead) genes are involved in the dorso-ventral patterning of the Xenopus mesoderm.

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El-Hodiri, H; Bhatia-Dey, N; Kenyon, K; Ault, K; Dirksen, M; Jamrich, M

2001-01-01

Fox (forkhead/winged helix) genes encode a family of transcription factors that are involved in embryonic pattern formation, regulation of tissue specific gene expression and tumorigenesis. Several of them are transcribed during Xenopus embryogenesis and are important for the patterning of ectoderm, mesoderm and endoderm. We have isolated three forkhead genes that are activated during gastrulation and play an important role in the dorso-ventral patterning of the mesoderm. XFKH1 (FoxA4b), the first vertebrate forkhead gene to be implicated in embryonic pattern formation, is expressed in the Spemann-Mangold organizer region and later in the embryonic notochord. XFKH7, the Xenopus orthologue of the murine Mfh1(Foxc2), is expressed in the presomitic mesoderm, but not in the notochord or lateral plate mesoderm. Finally, XFD-13'(FoxF1b)1 is expressed in the lateral plate mesoderm, but not in the notochord or presomitic mesoderm. Expression pattern and functional experiments indicate that these three forkhead genes are involved in the dorso-ventral patterning of the mesoderm.

Ranavirus in wild edible frogs Pelophylax kl. esculentus in Denmark

DEFF Research Database (Denmark)

Ariel, Ellen; Kielgast, Jos; Svart, Hans Erik

2009-01-01

interviewed by phone and 10 cases were examined on suspicion of diseaseinduced mortality. All samples were negative for Bd. Ranavirus was isolated from 2 samples of recently dead frogs collected during a mass mortality event in an artificial pond near Slagelse, Denmark. The identity of the virus was confirmed...

RMND5 from Xenopus laevis is an E3 ubiquitin-ligase and functions in early embryonic forebrain development.

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Pfirrmann, Thorsten; Villavicencio-Lorini, Pablo; Subudhi, Abinash K; Menssen, Ruth; Wolf, Dieter H; Hollemann, Thomas

2015-01-01

In Saccharomyces cerevisiae the Gid-complex functions as an ubiquitin-ligase complex that regulates the metabolic switch between glycolysis and gluconeogenesis. In higher organisms six conserved Gid proteins form the CTLH protein-complex with unknown function. Here we show that Rmnd5, the Gid2 orthologue from Xenopus laevis, is an ubiquitin-ligase embedded in a high molecular weight complex. Expression of rmnd5 is strongest in neuronal ectoderm, prospective brain, eyes and ciliated cells of the skin and its suppression results in malformations of the fore- and midbrain. We therefore suggest that Xenopus laevis Rmnd5, as a subunit of the CTLH complex, is a ubiquitin-ligase targeting an unknown factor for polyubiquitination and subsequent proteasomal degradation for proper fore- and midbrain development.

RMND5 from Xenopus laevis is an E3 ubiquitin-ligase and functions in early embryonic forebrain development.

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Thorsten Pfirrmann

Full Text Available In Saccharomyces cerevisiae the Gid-complex functions as an ubiquitin-ligase complex that regulates the metabolic switch between glycolysis and gluconeogenesis. In higher organisms six conserved Gid proteins form the CTLH protein-complex with unknown function. Here we show that Rmnd5, the Gid2 orthologue from Xenopus laevis, is an ubiquitin-ligase embedded in a high molecular weight complex. Expression of rmnd5 is strongest in neuronal ectoderm, prospective brain, eyes and ciliated cells of the skin and its suppression results in malformations of the fore- and midbrain. We therefore suggest that Xenopus laevis Rmnd5, as a subunit of the CTLH complex, is a ubiquitin-ligase targeting an unknown factor for polyubiquitination and subsequent proteasomal degradation for proper fore- and midbrain development.

Hypertrophy of mature xenopus muscle fibres in culture induced by synergy of albumin and insulin

NARCIS (Netherlands)

Jaspers, R.T.; van Beek-Harmsen, B.J.; Blankenstein, M.A.; Goldspink, G.; Huijing, P.A.J.B.M.; van der Laarse, W.J.

2008-01-01

The aim of this study was to investigate effects of albumin and insulin separately as well as in combination on mature muscle fibres during long-term culture. Single muscle fibres were dissected from m. iliofibularis of Xenopus laevis and attached to a force transducer in a culture chamber. Fibres

CRIM1 Complexes with ß-catenin and Cadherins, Stabilizes Cell-Cell Junctions and Is Critical for Neural Morphogenesis

OpenAIRE

Ponferrada, Virgilio G.; Fan, Jieqing; Vallance, Jefferson E.; Hu, Shengyong; Mamedova, Aygun; Rankin, Scott A.; Kofron, Matthew; Zorn, Aaron M.; Hegde, Rashmi S.; Lang, Richard A.

2012-01-01

In multicellular organisms, morphogenesis is a highly coordinated process that requires dynamically regulated adhesion between cells. An excellent example of cellular morphogenesis is the formation of the neural tube from the flattened epithelium of the neural plate. Cysteine-rich motor neuron protein 1 (CRIM1) is a single-pass (type 1) transmembrane protein that is expressed in neural structures beginning at the neural plate stage. In the frog Xenopus laevis, loss of function studies using C...

Reactive oxygen species formation during tetanic contractions in single isolated Xenopus myofibers

OpenAIRE

Zuo, Li; Nogueira, Leonardo; Hogan, Michael C.

2011-01-01

Contracting skeletal muscle produces reactive oxygen species (ROS) that have been shown to affect muscle function and adaptation. However, real-time measurement of ROS in contracting myofibers has proven to be difficult. We used amphibian (Xenopus laevis) muscle to test the hypothesis that ROS are formed during contractile activity in isolated single skeletal muscle fibers and that this contraction-induced ROS formation affects fatigue development. Single myofibers were loaded with 5 μM dihyd...

Narrative performance of gifted African American school-aged children from low-income backgrounds.

Science.gov (United States)

Mills, Monique T

2015-02-01

This study investigated classroom differences in the narrative performance of school-age African American English (AAE)-speaking children in gifted and general education classrooms. Forty-three children, Grades 2-5, each generated fictional narratives in response to the book Frog, Where Are You? (Mayer, 1969). Differences in performance on traditional narrative measures (total number of communication units [C-units], number of different words, and mean length of utterance in words) and on AAE production (dialect density measure) between children in gifted and general education classrooms were examined. There were no classroom-based differences in total number of C-units, number of different words, and mean length of utterance in words. Children in gifted education classrooms produced narratives with lower dialect density than did children in general educated classrooms. Direct logistic regression assessed whether narrative dialect density measure scores offered additional information about giftedness beyond scores on the Peabody Picture Vocabulary Test-Fourth Edition (Dunn & Dunn, 2007), a standard measure of language ability. Results indicated that a model with only Peabody Picture Vocabulary Test-Fourth Edition scores best discriminated children in the 2 classrooms. African American children across gifted and general education classrooms produce fictional narratives of similar length, lexical diversity, and syntax complexity. However, African American children in gifted education classrooms may produce lower rates of AAE and perform better on standard measures of vocabulary than those in general education classrooms.

Developmental changes in drug-metabolizing enzyme expression during metamorphosis of Xenopus tropicalis.

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Mori, Junpei; Sanoh, Seigo; Kashiwagi, Keiko; Hanada, Hideki; Shigeta, Mitsuki; Suzuki, Ken-Ichi T; Yamamoto, Takashi; Kotake, Yaichiro; Sugihara, Kazumi; Kitamura, Shigeyuki; Kashiwagi, Akihiko; Ohta, Shigeru

2017-01-01

A large number of chemicals are routinely detected in aquatic environments, and these chemicals may adversely affect aquatic organisms. Accurate risk assessment requires understanding drug-metabolizing systems in aquatic organisms because metabolism of these chemicals is a critical determinant of chemical bioaccumulation and related toxicity. In this study, we evaluated mRNA expression levels of nuclear receptors and drug-metabolizing enzymes as well as cytochrome P450 (CYP) activities in pro-metamorphic tadpoles, froglets, and adult frogs to determine how drug-metabolizing systems are altered at different life stages. We found that drug-metabolizing systems in tadpoles were entirely immature, and therefore, tadpoles appeared to be more susceptible to chemicals compared with metamorphosed frogs. On the other hand, cyp1a mRNA expression and CYP1A-like activity were higher in tadpoles. We found that thyroid hormone (TH), which increases during metamorphosis, induced CYP1A-like activity. Because endogenous TH concentration is significantly increased during metamorphosis, endogenous TH would induce CYP1A-like activity in tadpoles.

Pecular Features of Hematopoiesis in the Liver of Mature and Immature Green Frogs (Pelophylax Esculentus Complex

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Akulenko N. M.

2016-12-01

Full Text Available The article describes characteristic features of the hematopoiesis in mature and immature green frogs (Pelophylax esculentus complex. Quantitative differences in liver myelograms were insignificant. However, in a sample of mature animals numerous significant correlations between the number of pigment inclusions in the liver and indicators of erythropoiesis and myelopoiesis were observed. Those correlations were absent in the immature frogs. We concluded that aft er the frogs’ breeding a lack of plastic resources, in particular, hemosiderin remains up to the hibernation.

Helminth parasites of the levantine frog (Pelophylax bedriagae Camerano, 1882 from the western part of Turkey

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Demır S.

2015-02-01

Full Text Available Fifty-four Pelophylax bedriagae (Levantine Frog from Turkey (İzmir and Manisa Provinces were examined for helminth parasites. The frogs were collected between 2012 and 2014 years. Eight species of helminth parasites were recorded: 3 species of Nematoda (Rhabdias bufonis, Cosmocerca ornata, Oswaldocruzia filiformis, 3 species of Digenea (Diplodiscus subclavatus, Haematoloechus bre-viansa, Gorgoderina vitelliloba, 1 species of Acanthocephala (Acanthocephalus ranae and 1 species of Hirudinea (Hirudo medicinalis. Pelophylax bedriagae is a new host record for these parasite species.

Underestimation of species richness in neotropical frogs revealed by mtDNA analyses.

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Antoine Fouquet

2007-10-01

Full Text Available Amphibians are rapidly vanishing. At the same time, it is most likely that the number of amphibian species is highly underestimated. Recent DNA barcoding work has attempted to define a threshold between intra- and inter-specific genetic distances to help identify candidate species. In groups with high extinction rates and poorly known species boundaries, like amphibians, such tools may provide a way to rapidly evaluate species richness.Here we analyse published and new 16S rDNA sequences from 60 frog species of Amazonia-Guianas to obtain a minimum estimate of the number of undescribed species in this region. We combined isolation by distance, phylogenetic analyses, and comparison of molecular distances to evaluate threshold values for the identification of candidate species among these frogs.In most cases, geographically distant populations belong to genetically highly distinct lineages that could be considered as candidate new species. This was not universal among the taxa studied and thus widespread species of Neotropical frogs really do exist, contrary to previous assumptions. Moreover, the many instances of paraphyly and the wide overlap between distributions of inter- and intra-specific distances reinforce the hypothesis that many cryptic species remain to be described. In our data set, pairwise genetic distances below 0.02 are strongly correlated with geographical distances. This correlation remains statistically significant until genetic distance is 0.05, with no such relation thereafter. This suggests that for higher distances allopatric and sympatric cryptic species prevail. Based on our analyses, we propose a more inclusive pairwise genetic distance of 0.03 between taxa to target lineages that could correspond to candidate species.Using this approach, we identify 129 candidate species, two-fold greater than the 60 species included in the current study. This leads to estimates of around 170 to 460 frog taxa unrecognized in Amazonia

Extracellular quaternary ammonium blockade of transient receptor potential vanilloid subtype 1 channels expressed in Xenopus laevis oocytes

DEFF Research Database (Denmark)

Rivera-Acevedo, Ricardo E; Pless, Stephan Alexander; Schwarz, Stephan K W

2012-01-01

expressed in Xenopus laevis oocytes, whereas the neutral local anesthetic, benzocaine, does not, suggesting that a titratable amine is required for high-affinity inhibition. Consistent with this possibility, extracellular tetraethylammonium (TEA) and tetramethylammonium application produces potent, voltage...

Variable Alkaloid Defenses in the Dendrobatid Poison Frog Oophaga pumilio are Perceived as Differences in Palatability to Arthropods.

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Bolton, Sarah K; Dickerson, Kelsie; Saporito, Ralph A

2017-03-01

Conspicuously colored dendrobatid frogs sequester alkaloid defenses from dietary arthropods, resulting in considerable alkaloid variation among populations; however, little is known about how variation is perceived as a defense against predators. Previous studies have found variable alkaloids in the dendrobatid Oophaga pumilio to be associated with differences in toxicity to laboratory mice, suggesting variable defenses are important. Arthropods are natural predators that use chemoreception to detect prey, including frogs, and may therefore perceive variation in alkaloid profiles as differences in palatability. The goal of the present study is to determine how arthropods respond to variable alkaloid defenses in O. pumilio. Frog alkaloids were sampled from individual O. pumilio from ten geographic locations throughout the Bocas del Toro region of Panama and the Caribbean coast of Costa Rica. Alkaloid extracts were used in feeding bioassays with the vinegar fly Drosophila melanogaster and the ant Ectatomma ruidum. Both species of arthropods fed significantly less on frog alkaloid extracts when compared to controls, and differences in alkaloid palatability were observed among frog populations, as well as between sexes and life stages within a population. Differences in alkaloid quantity, richness, and type were the main predictors of arthropod palatability. Our findings also represent the first direct evidence of a palatability spectrum in a vertebrate that sequesters chemical defenses from dietary sources. Further, the presence of a palatability spectrum suggests that variable alkaloid defenses in O. pumilio are ecologically relevant and play an important role in natural predator-prey interactions, particularly with respect to arthropod predators.

Analysis of skin derived peptides from the Cuyaba Dwarf Frog Physalaemus nattereri by off-line LC MALDI MS/MS

DEFF Research Database (Denmark)

Castro, Mariana S; Pires Júnior, Osmindo Rodrigues; Fontes, Wagner

2017-01-01

We have investigated the potential for analysis of the complex peptide mixtures secreted from frog skin using off-line LC-MALDI MS/MS. Since only limited information about the sequence of such peptides is available, de novo sequencing followed by Blast search was needed. An automated workflow has...... for future studies of peptides secreted from frogs....

REGIONAL DYNAMICS OF WETLAND-BREEDING FROGS AND TOADS: TURNOVER AND SYNCHRONY

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We used data from a statewide frog monitoring network to investigate population turnover and synchrony in eight wetland-breeding species. We found that subpopulations at many sites turn over frequently, with breeding choruses absent or undetectable in most years. Frequencies of d...

Is the red spotted green frog Hypsiboas punctatus (Anura: Hylidae) selecting its preys? The importance of prey availability.

Science.gov (United States)

López, Javier A; Scarabotti, Pablo A; Medrano, María C; Ghirardi, Romina

2009-09-01

The study of the feeding ecology of amphibians is an old issue in herpetology. Notwithstanding, the lack of food resources data in many studies of amphibians feeding has lead to partial understanding of frog feeding strategies. In this study we evaluate the trophic selectivity of a red spotted green frog (Hypsiboas punctatus) population from a Middle Paraná River floodplain pond in Argentina, and discuss the importance of prey availability data when interpreting results from diet analysis. We analyzed the gut contents of 47 H. punctatus adults and compared frog's diet with the environmental food resources. Prey availability was estimated by systematically seep-netting the microhabitat where anurans were localized foraging. We identified 33 taxonomic categories from gastrointestinal contents. Numerically, the most important prey categories were dipterans, followed by hemipterans, homopterans and coleopterans. The diet similarity between males and females was high and no statistical differences in diet composition were found. The most abundant food resources in the environment were dipterans, coleopterans, homopterans and collembolans. In order to assess whether frogs were selecting their preys, we calculated Pianka's niche overlap index and Jacobs' electivity index comparing gut contents to prey availability data. Trophic niche overlap was medium but significantly higher than expected by chance. The electivity index indicated that H. punctatus foraged dipterans slightly above their environmental abundance. Among the secondary preys, hemipterans were foraged selectively, homopterans were consumed in the same proportion to their occurrence in the environment, coleopterans were foraged quite under their availability and collembolans were practically ignored by frogs. Without food resources data, H. punctatus could be classified as a specialist feeder, but dipterans also were quite abundant in the environment. Our results show that H. punctatus fit better as a

Breeding Guild Determines Frog Distributions in Response to Edge Effects and Habitat Conversion in the Brazil's Atlantic Forest.

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Rodrigo B Ferreira

Full Text Available Understanding the response of species with differing life-history traits to habitat edges and habitat conversion helps predict their likelihood of persistence across changing landscape. In Brazil's Atlantic Forest, we evaluated frog richness and abundance by breeding guild at four distances from the edge of a reserve: i 200 m inside the forest, ii 50 m inside the forest, iii at the forest edge, and iv 50 m inside three different converted habitats (coffee plantation, non-native Eucalyptus plantation, and abandoned pastures, hereafter matrix types. By sampling a dry and a wet season, we recorded 622 individual frogs representing 29 species, of which three were undescribed. Breeding guild (i.e. bromeliad, leaf-litter, and water-body breeders was the most important variable explaining frog distributions in relation to edge effects and matrix types. Leaf-litter and bromeliad breeders decreased in richness and abundance from the forest interior toward the matrix habitats. Water-body breeders increased in richness toward the matrix and remained relatively stable in abundance across distances. Number of large trees (i.e. DBH > 15 cm and bromeliads best explained frog richness and abundance across distances. Twenty species found in the interior of the forest were not found in any matrix habitat. Richness and abundance across breeding guilds were higher in the rainy season but frog distributions were similar across the four distances in the two seasons. Across matrix types, leaf-litter species primarily used Eucalyptus plantations, whereas water-body species primarily used coffee plantations. Bromeliad breeders were not found inside any matrix habitat. Our study highlights the importance of primary forest for bromeliad and leaf-litter breeders. We propose that water-body breeders use edge and matrix habitats to reach breeding habitats along the valleys. Including life-history characteristics, such as breeding guild, can improve predictions of frog

Breeding Guild Determines Frog Distributions in Response to Edge Effects and Habitat Conversion in the Brazil's Atlantic Forest.

Science.gov (United States)

Ferreira, Rodrigo B; Beard, Karen H; Crump, Martha L

2016-01-01

Understanding the response of species with differing life-history traits to habitat edges and habitat conversion helps predict their likelihood of persistence across changing landscape. In Brazil's Atlantic Forest, we evaluated frog richness and abundance by breeding guild at four distances from the edge of a reserve: i) 200 m inside the forest, ii) 50 m inside the forest, iii) at the forest edge, and iv) 50 m inside three different converted habitats (coffee plantation, non-native Eucalyptus plantation, and abandoned pastures, hereafter matrix types). By sampling a dry and a wet season, we recorded 622 individual frogs representing 29 species, of which three were undescribed. Breeding guild (i.e. bromeliad, leaf-litter, and water-body breeders) was the most important variable explaining frog distributions in relation to edge effects and matrix types. Leaf-litter and bromeliad breeders decreased in richness and abundance from the forest interior toward the matrix habitats. Water-body breeders increased in richness toward the matrix and remained relatively stable in abundance across distances. Number of large trees (i.e. DBH > 15 cm) and bromeliads best explained frog richness and abundance across distances. Twenty species found in the interior of the forest were not found in any matrix habitat. Richness and abundance across breeding guilds were higher in the rainy season but frog distributions were similar across the four distances in the two seasons. Across matrix types, leaf-litter species primarily used Eucalyptus plantations, whereas water-body species primarily used coffee plantations. Bromeliad breeders were not found inside any matrix habitat. Our study highlights the importance of primary forest for bromeliad and leaf-litter breeders. We propose that water-body breeders use edge and matrix habitats to reach breeding habitats along the valleys. Including life-history characteristics, such as breeding guild, can improve predictions of frog distributions in

Correlates of virulence in a frog-killing fungal pathogen: evidence from a California amphibian decline.

Science.gov (United States)

Piovia-Scott, Jonah; Pope, Karen; Worth, S Joy; Rosenblum, Erica Bree; Poorten, Thomas; Refsnider, Jeanine; Rollins-Smith, Louise A; Reinert, Laura K; Wells, Heather L; Rejmanek, Dan; Lawler, Sharon; Foley, Janet

2015-07-01

The fungal pathogen Batrachochytrium dendrobatidis (Bd) has caused declines and extinctions in amphibians worldwide, and there is increasing evidence that some strains of this pathogen are more virulent than others. While a number of putative virulence factors have been identified, few studies link these factors to specific epizootic events. We documented a dramatic decline in juvenile frogs in a Bd-infected population of Cascades frogs (Rana cascadae) in the mountains of northern California and used a laboratory experiment to show that Bd isolated in the midst of this decline induced higher mortality than Bd isolated from a more stable population of the same species of frog. This highly virulent Bd isolate was more toxic to immune cells and attained higher density in liquid culture than comparable isolates. Genomic analyses revealed that this isolate is nested within the global panzootic lineage and exhibited unusual genomic patterns, including increased copy numbers of many chromosomal segments. This study integrates data from multiple sources to suggest specific phenotypic and genomic characteristics of the pathogen that may be linked to disease-related declines.

Population recovery following decline in an endangered stream-breeding frog (Mixophyes fleayi from subtropical Australia.

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David Alan Newell

Full Text Available Amphibians have undergone dramatic declines and extinctions worldwide. Prominent among these have been the stream-breeding frogs in the rainforests of eastern Australia. The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd has been postulated as the primary cause of these declines. We conducted a capture-mark-recapture study over a 7-year period on the endangered Fleay's barred frog (Mixophyes fleayi at two independent streams (30 km apart in order to assess the stability of these populations. This species had undergone a severe decline across its narrow geographic range. Mark-recapture modelling showed that the number of individuals increased 3-10 fold along stream transects over this period. Frog detection probabilities were frequently above 50% but declined as the populations increased. Adult survival was important to overall population persistence in light of low recruitment events, suggesting that longevity may be a key factor in this recovery. One male and female were present in the capture record for >6 years. This study provides an unambiguous example of population recovery in the presence of Bd.

Taxonomy Icon Data: Japanese tree frog [Taxonomy Icon

Lifescience Database Archive (English)

Full Text Available Japanese tree frog Hyla japonica Chordata/Vertebrata/Amphibia Hyla_japonica_L.png Hyla_jap...onica_NL.png Hyla_japonica_S.png Hyla_japonica_NS.png http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Hyla+jap...onica&t=L http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Hyla+japonica&t=NL http://biosciencedbc....jp/taxonomy_icon/icon.cgi?i=Hyla+japonica&t=S http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Hyla+jap

A new Gephyromantis (Phylacomantis frog species from the pinnacle karst of Bemaraha, western Madagascar

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Angelica Crottini

2011-02-01

Full Text Available We describe a new mantellid frog of the subfamily Mantellinae from the karstic Bemaraha Plateau, western Madagascar. The new species belongs to the genus Gephyromantis, subgenus Phylacomantis, which previously included G. azzurrae, G. corvus and G. pseudoasper. Gephyromantis atsingy sp. n. has a snout-vent length of 35–43 mm and is a scansorial frog living among the Tsingy de Bemaraha pinnacles and inside the caves present in the area. A morphological analysis and biomolecular comparison revealed the degree of differentiation between these four species of the Phylacomantis subgenus. The new species seems to be endemic to Tsingy de Bemaraha.

Water balance of field-excavated aestivating Australian desert frogs, the cocoon-forming Neobatrachus aquilonius and the non-cocooning Notaden nichollsi (Amphibia: Myobatrachidae).

Science.gov (United States)

Cartledge, Victoria A; Withers, Philip C; McMaster, Kellie A; Thompson, Graham G; Bradshaw, S Don

2006-09-01

Burrowed aestivating frogs of the cocoon-forming species Neobatrachus aquilonius and the non-cocooning species Notaden nichollsi were excavated in the Gibson Desert of central Australia. Their hydration state (osmotic pressure of the plasma and urine) was compared to the moisture content and water potential of the surrounding soil. The non-cocooning N. nichollsi was consistently found in sand dunes. While this sand had favourable water potential properties for buried frogs, the considerable spatial and temporal variation in sand moisture meant that frogs were not always in positive water balance with respect to the surrounding soil. The cocoon-forming N. aquilonius was excavated from two distinct habitat types, a claypan in which frogs had a well-formed cocoon and a dune swale where frogs did not have a cocoon. Cocoons of excavated frogs ranged in thickness from 19.4 microm to 55.61 microm and consisted of 81-229 layers. Cocooned claypan N. aquilonius were nearing exhaustion of their bladder water reserves and had a urine osmolality approaching that of the plasma. By contrast, non-cocooned N. aquilonius from the dune swale were fully hydrated, although soil moisture levels were not as high as calculated to be necessary to maintain water balance. Both species had similar plasma arginine vasotocin (AVT) concentrations ranging from 9.4 to 164 pg ml(-1), except for one cocooned N. aquilonius with a higher concentration of 394 pg ml(-1). For both species, AVT showed no relationship with plasma osmolality over the lower range of plasma osmolalities but was appreciably increased at the highest osmolality recorded. This study provides the first evidence that cocoon formation following burrowing is not obligatory in species that are capable of doing so, but that cocoon formation occurs when soil water conditions are more desiccating than for non-cocooned frogs.

The effects of aquatic oxygen concentration, body size and respiratory behaviour on the stamina of obligate aquatic (Bufo americanus) and facultative air-breathing (Xenopus laevis and Rana berlandieri) anuran larvae.

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Wassersug, R J; Feder, M E

1983-07-01

Larvae of the anurans Rana berlandieri and Xenopus laevis have lungs and can breathe air as well as irrigate buccal and pharyngeal surfaces for aquatic respiration. Larvae of Bufo americanus lack lungs until just before metamorphosis and are obligately aquatic. We examined the relationship between the locomotor stamina (time to fatigue), aquatic oxygen concentration, body size, and respiratory behaviour of swimming larvae of these species, with the following results: Stamina is size-dependent in all three species. Aquatic hypoxia reduces stamina in larvae of all three species, but most conspicuously in Bufo. Breathing air increases stamina in Rana larvae, especially in large animals and under aquatic hypoxia. In contrast to Rana larvae, Xenopus larvae swimming in normoxic water undergo a reduction in stamina when allowed to breathe air. In hypoxic water, aerial respiration moderates the reduction in stamina seen in Xenopus larvae. Branchial irrigation is associated with increased stamina in Xenopus, and is increased under hypoxia and at high swimming velocities. Respiratory demand, buoyancy and the drag associated with branchial irrigation all affect respiratory behaviour in Xenopus larvae. The great amount of interspecific variation in the relationship between respiratory behaviour and stamina reveals the importance of measuring performance directly when attempting to interpret the functional significance of respiratory structures and behaviour.

Control of melanin synthesis during oogenesis in Xenopus laevis

Energy Technology Data Exchange (ETDEWEB)

Kidson, S H

1985-01-01

The present study investigates the mechanisms that control the synthesis of pigment during Xenopus laevis oogenesis. In this study, in vitro and in vivo assays indicate that the activity of the enzyme tyrosinase, the only enzyme necessary for the synthesis of pigment also reaches a peak during mid-oogenesis. The isotopes carbon 14, tritium, phosphorus 32 and sulfur 35 are used in this experiments. Furthermore, in vitro tyrosinase assays of polysomes isolated from different stage oocytes show that the rise in tyrosinase activity during mid-oogenesis is accompanied by a rise in polysomes synthesizing tyrosinase. This suggests that the synthesis of tyrosinase is restricted to mid-oogenesis. It was also established that oocyte tyrosinase is synthesized as a 32 kd polypeptide and is processed intra-melanosomally into a 120-130 kd tetramer. It is this form that is catalytically active in vivo. Oocyte tyrosinase does not require post-translational protease activation. To investigate the hypothesis that the synthesis of tyrosinase is restricted to mid-oogenesis, the accumulation of messenger RNA coding for tyrosinase was measured at different stages of oogenesis using a tyrosinase cDNA probe. The preparation of the tyrosinase cDNA probe required the purification of tyrosinase mRNA. This was achieved by a technique based on affinity chromatography of polysomes. This enriched 'tyrosinase mRNA' translated in vitro into two major proteins of 32 kd and 20 kd. The mRNA microinjected into Xenopus oocytes is translated into active tyrosinase. Hybridization of the tyrosinase cDNA probe to dot blots of oocyte mRNA suggested that tyrosinase mRNA accumulation reaches a peak just before maximal tyrosinase synthesis. The absence of tyrosinase mRNA late in oogenesis suggests that this message is not synthesized at this stage. These results are interpreted in terms of the functional significance of lampbrush chromosomes.

The use of singleplex and nested PCR to detect Batrachochytrium dendrobatidis in free-living frogs.

Science.gov (United States)

Coutinho, Selene Dall'Acqua; Burke, Julieta Catarina; de Paula, Catia Dejuste; Rodrigues, Miguel Trefaut; Catão-Dias, José Luiz

2015-06-01

Many microorganisms are able to cause diseases in amphibians, and in the past few years one of the most reported has been Batrachochytrium dendrobatidis. This fungus was first reported in Brazil in 2005; following this, other reports were made in specimens deposited in museum collections, captive and free-living frogs. The aim of this study was to compare singleplex and nested-PCR techniques to detect B. dendrobatidis in free-living and apparently healthy adult frogs from the Brazilian Atlantic Forest. The sample collection area was a protected government park, with no general entrance permitted and no management of the animals there. Swabs were taken from the skin of 107 animals without macroscopic lesions and they were maintained in ethanol p.a. Fungal DNA was extracted and identification of B. dendrobatidis was performed using singleplex and nested-PCR techniques, employing specific primers sequences. B. dendrobatidis was detected in 61/107 (57%) and 18/107 (17%) animals, respectively by nested and singleplex-PCR. Nested-PCR was statistically more sensible than the conventional for the detection of B. dendrobatidis (Chi-square = 37.1; α = 1%) and the agreement between both techniques was considered just fair (Kappa = 0.27). The high prevalence obtained confirms that these fungi occur in free-living frogs from the Brazilian Atlantic Forest with no macroscopic lesions, characterizing the state of asymptomatic carrier. We concluded that the nested-PCR technique, due to its ease of execution and reproducibility, can be recommended as one of the alternatives in epidemiological surveys to detect B. dendrobatidis in healthy free-living frog populations.

Four new species of frogs and one new species of snake from the Chapare region of Bolivia, with notes on other species

Science.gov (United States)

Reynolds, R.P.; Foster, M.S.

1992-01-01

We report on a collection of 74 frogs, 11 lots of frog eggs or tadpoles, and two snakes collected from the Chapare Region in the yungas of the eastern Andean Cordillera de Cochabamba, Bolivia. Collecting localities range from approximately 300 m to >3200 m in elevation. The specimens pertain to 23 species, probably 10 of which are undescribed. We describe four new species of frogs, one each in the genera Bufo, Centrolenella, Colostethus, and Hyla, and one new species of snake, genus Dipsas. We place Atelopus rugulosus in synonymy with A. tricolor.

Roles of ADAM13-regulated Wnt activity in early Xenopus eye development

OpenAIRE

Wei, Shuo; Xu, Guofeng; Bridges, Lance C.; Williams, Phoebe; Nakayama, Takuya; Shah, Anoop; Grainger, Robert M.; White, Judith M.; DeSimone, Douglas W.

2011-01-01

Pericellular proteolysis by ADAM family metalloproteinases has been widely implicated in cell signaling and development. We recently found that Xenopus ADAM13, an ADAM metalloproteinase, is required for activation of canonical Wnt signaling during cranial neural crest (CNC) induction by regulating a novel crosstalk between Wnt and ephrin B (EfnB) signaling pathways (Wei et al., 2010b). In the present study we show that the metalloproteinase activity of ADAM13 also plays important roles in eye...

The Xenopus Oocyte: A Single-Cell Model for Studying Ca2+ Signaling

OpenAIRE

Lin-Moshier, Yaping; Marchant, Jonathan S.

2013-01-01

In the four decades since the Xenopus oocyte was first demonstrated to have the capacity to translate exogenous mRNAs, this system has been exploited for many different experimental purposes. Typically, the oocyte is used either as a “biological test tube” for heterologous expression of proteins without any particular cell biological insight or, alternatively, it is used for applications where cell biology is paramount, such as investigations of the cellular adaptations that power early devel...

Morfologfa conchffera, crecimiento, reproducción y letargo de los caracoles gigantes africanos : observaciones en laboratorio sobre Archachatina marginata suturalis, Achatina achatina y Achatina fulica'

Directory of Open Access Journals (Sweden)

Stiévenart, C.

1997-01-01

Full Text Available hell Shape, Growth, Reproduction and Estivation in Giant African Landsnails : Observations in Laboratory on"Archachatina marginata suturalis, Achatina achatina and Achatina fulica". Commercial frog farms exist in several countries. It seems hopeless believing that frog leg consumption can be prohibited, and the solution is probably a very strict control of the origin of the legs sold and imported. Uncontrolled hunting-poaching of frogs should be replaced by sustainable and rational breeding of frogs for sale. A large frog farm located near Singapore is described with the infrastructure and the management of the production. The two species bred are the American and the Asian bull-frogs Rana catesbeiana and R. tigerina. It is also mentioned that appropriate slaughtering techniques exist for frogs based on same guidelines as for conventional farm animals.