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F Orton, M Säfholm, E Jansson, Y Carlsson, A Eriksson, J Fick, T Uren Webster, T McMillan, M Leishman, B Verbruggen, T Economou, C R Tyler, C Berg
Amphibians are threatened on a global scale and pollutants may be contributing to population declines, but how chemicals impact on their reproduction is poorly understood. We conducted a life cycle analysis to investigate the impacts of early life exposure to two anti-androgens (exposure until completion of metamorphosis;stage 66): flutamide, (50 µg/L)/linuron (9 and 45 µg/L)) on sexual development and breeding competence in Xenopus tropicalis. Our analyses included: mRNA levels of dmrt1, cyp17, amh, cyp19, foxl2 and ar (tadpoles/metamorphs), gonadal histomorphology (metamorphs/adults), mRNA levels of ar/gr (adult male brain/gonad/forelimb), testosterone/corticosterone levels (adult males), secondary sexual characteristics (forelimb width/nuptial pad: adult males) and breeding competence (amplexus/fertility: adult males)...
June 14, 2018: Scientific Reports
Mark E Pownall, Ronald R Cutler, Margaret S Saha
Although polyploidy occurs throughout the fish and amphibian lineages, the Xenopus genus exhibits a high incidence of polyploidy, with 25 out of the 26 known species being polyploid. However, transcriptomic information is currently available for only one of these species, the tetraploid Xenopus laevis. Xenopus andrei, an octoploid species within the Xenopus genus, offers an opportunity for assessing a novel polyploid transcriptome during vertebrate development. RNA-Seq data was generated at nine different developmental stages ranging from unfertilized eggs through swimming tadpole stages and raw FASTQ files were deposited in the NCBI SRA database (accession number SRP134281)...
August 2018: Data in Brief
Richard Mollard
These data and analyses support the research article "Culture, cryobanking and passaging of karyotypically validated native Australian amphibian cells" Mollard (2018) [1]. The data and analyses presented here include: (1) three additional karyomaps of cells from the cryobanked and passaged frog and tadpole species Litoria infrafrenata ; and (2) combined short-to-long arm ratios of the four karyomaps measured from each respective animal here and in Ref [1].
June 2018: Data in Brief
Nicolas Buisine, Xiaoan Ruan, Yijun Ruan, Laurent M Sachs
Proper gene expression involves communication between the regulatory elements and promoters of genes. Today, chromosome conformation capture (3C)-based methods efficiently probe chromosome folding in the nucleus and thus provide a molecular description of physical proximity through DNA looping between enhancer(s) and their target promoter(s). One such method, chromatin interaction analysis using paired-end-tag (ChIA-PET) sequencing is a powerful high-throughput method for detection of genome-wide chromatin interactions...
June 12, 2018: Cold Spring Harbor Protocols
Nicolas Buisine, Xiaoan Ruan, Yijun Ruan, Laurent M Sachs
Proper gene expression involves communication between the regulatory elements and promoters of genes. Because regulatory elements can be located over a large range of genomic distances (from as close as a few hundred bp to as much as several Mb away), contact and communication between regulators and the core transcriptional machinery at promoters are mediated through DNA looping. Today, chromosome conformation capture (3C)-based methods efficiently probe chromosome folding in the nucleus and thus provide a molecular description of physical proximity between enhancer(s) and their target promoter(s)...
June 12, 2018: Cold Spring Harbor Protocols
Xiaoxuan Yang, Youssef Jounaidi, Jennifer B Dai, Francisco Marte-Oquendo, Elizabeth S Halpin, Lauren E Brown, Richard Trilles, Wenqing Xu, Renee Daigle, Buwei Yu, Scott E Schaus, John A Porco, Stuart A Forman
BACKGROUND: Many general anesthetics were discovered empirically, but primary screens to find new sedative-hypnotics in drug libraries have not used animals, limiting the types of drugs discovered. The authors hypothesized that a sedative-hypnotic screening approach using zebrafish larvae responses to sensory stimuli would perform comparably to standard assays, and efficiently identify new active compounds. METHODS: The authors developed a binary outcome photomotor response assay for zebrafish larvae using a computerized system that tracked individual motions of up to 96 animals simultaneously...
June 12, 2018: Anesthesiology
Angélica Arenas-Rodríguez, Juan Francisco Rubiano Vargas, Julio Mario Hoyos
Although comparative studies of anuran ontogeny have provided new data on heterochrony in the life cycles of frogs, most of them have not included ossification sequences. Using differential staining techniques, we observe and describe differences and similarities of cranial and postcranial development in two hylid species, Scinax ruber (Scinaxinae) and Dendropsophus labialis (Hylinae), providing new data of ontogenetic studies in these Colombian species. We examined tadpoles raining from Gosner Stages 25 to 45...
2018: PeerJ
Mitchell D Reed, Kimberly E Iceman, Michael B Harris, Barbara E Taylor
The development of amphibian breathing provides insight into vertebrate respiratory control mechanisms. Neural oscillators in the rostral and caudal medulla drive ventilation in amphibians, and previous reports describe ventilatory oscillators and CO2 sensitive regions arise during different stages of amphibian metamorphosis. However, inconsistent findings have been enigmatic, and make comparisons to potential mammalian counterparts challenging. In the current study we assessed amphibian central CO2 responsiveness and respiratory rhythm generation during two different developmental stages...
June 8, 2018: Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology
A Marta, N Kamenshchik, I Toderas
The present study documents three specimens of Benthophiloides brauneri from the River Dniester. It is one of the rarest freshwater fishes in Europe, living along the western coast of the Black and Asov Seas, but these new records are 200 river km from the coast. We discuss whether the species has recently started to establish inland populations or inland specimens have previously been overlooked. This article is protected by copyright. All rights reserved.
June 7, 2018: Journal of Fish Biology
Elvis Almeida Pereira, Lucas Custódio Lomba Rocha, Henrique Folly, Hélio Ricardo da Silva, Diego José Santana
Based on concordant differences in male advertisement call, tadpole morphology, and absence of haplotype sharing in the barcoding 16S mitochondrial DNA, we describe here a new species of spotted leaf frog of the genus Phasmahyla from Atlantic Forest, State of Rio de Janeiro, Southeast Brazil. The new species is most similar to P. cochranae (type locality) and P. spectabilis (type locality). It differs from these species by the size of the calcar, moderate-sized body (snout-vent length 30.4-34.4 mm in adult eight males), and in the advertisement call...
2018: PeerJ
Masaki Nakano, Itaru Hasunuma, Atsuko Minagawa, Shawichi Iwamuro, Kazutoshi Yamamoto, Sakae Kikuyama, Takeo Machida, Tetsuya Kobayashi
In amphibians, thyrotropin (TSH), corticotropin (ACTH) and prolactin (PRL) are regarded as the major pituitary hormones involved in metamorphosis and known to be controlled by corticotropin-releasing factor (CRF), arginine vasotocin (AVT), and thyrotropin-releasing hormone (TRH), respectively. It is also known that thyrotropes and corticotropes are equipped with CRF type-2 receptor and AVT V1b receptor, respectively. As for PRL cells, information about the type of receptor for TRH (TRHR) through which the action of TRH is mediated to induce the release of PRL is lacking...
June 1, 2018: General and Comparative Endocrinology
Francisca Bermedo-García, Jorge Ojeda, Emilio E Méndez-Olivos, Sylvain Marcellini, Juan Larraín, Juan Pablo Henríquez
The frog neuromuscular junction (NMJ) has been extensively used as a model system to dissect the mechanisms involved in synapse formation, maturation, maintenance, regeneration, and function. Early NMJ synaptogenesis relies on a combination of cell-autonomous and interdependent pre/postsynaptic communication processes. Due to their transparency, comparatively easy manipulation, and remarkable regenerative abilities, frog tadpoles constitute an excellent model to study NMJ formation and regeneration. Here, we aimed to contribute new aspects on the characterization of the ontogeny of NMJ formation in Xenopus embryos and to explore the morphological changes occurring at the NMJ after spinal cord injury...
May 25, 2018: Mechanisms of Development
Michelle M Giarmarco, Whitney M Cleghorn, James B Hurley, Susan E Brockerhoff
The retina is a complex tissue that initiates and integrates the first steps of vision. Dysfunction of retinal cells is a hallmark of many blinding diseases, and future therapies hinge on fundamental understandings about how different retinal cells function normally. Gaining such information with biochemical methods has proven difficult because contributions of particular cell types are diminished in the retinal cell milieu. Live retinal imaging can provide a view of numerous biological processes on a subcellular level, thanks to a growing number of genetically encoded fluorescent biosensors...
May 9, 2018: Journal of Visualized Experiments: JoVE
Beatrice Lindgren, Germán Orizaola, Anssi Laurila
Fast-growing genotypes living in time-constrained environments are often more prone to predation, suggesting that growth-predation risk trade-offs are important factors maintaining variation in growth along climatic gradients. However, the mechanisms underlying how fast growth increases predation-mediated mortality are not well understood. Here, we investigated if slow-growing, low-latitude individuals have faster escape swimming speed than fast-growing high-latitude individuals using common frog (Rana temporaria) tadpoles from eight populations collected along a 1500 km latitudinal gradient...
May 26, 2018: Journal of Evolutionary Biology
Katharina Ruthsatz, Myron A Peck, Kathrin H Dausmann, Nikita M Sabatino, Julian Glos
Anurans exhibit plasticity in the timing of metamorphosis and tadpoles show phenotypic plasticity in age and size at metamorphosis as a response to temperature variation. This developmental plasticity to changing thermal conditions is expected to be a primary factor that dictates the vulnerability of amphibians to increasing ambient temperatures such as are predicted in climate change scenarios. We analyzed the patterns of thermal effects on size and age at metamorphosis to investigate whether the intraspecific "temperature-size rule" is applicable over a broad range of anuran species by carrying out a combined analysis based on the data from 25 studies performed on 18 anuran species...
May 2018: Journal of Thermal Biology
Max R Lambert, Meredith S Smylie, Amber J Roman, L Kealoha Freidenburg, David K Skelly
All amphibian species are known to have genetic sex determination. However, a variety of environmental conditions can moderate sexual differentiation, in some cases leading to sex reversal and skewed sex ratios. While there has been a recent focus on chemically-induced sex reversal in amphibians, temperature can also influence sexual differentiation. Building upon a classic 1929 study by Emil Witschi, we assessed temperature-mediated sex reversal. Witschi found that the wood frog sex ratio is 100% male at a high temperature (32°C) compared to a 50:50 sex ratio at 20°C...
May 23, 2018: Journal of Experimental Zoology. Part A, Ecological and Integrative Physiology
Reyna I Martinez-De Luna, Michael E Zuber
Genetically controlled cell type-specific ablation provides a reproducible method to induce regeneration that can be temporally and spatially controlled. Until recently, regeneration studies in Xenopus have relied on surgical methods to stimulate regeneration. These methods are labor intensive and not as reproducible as a genetically controlled approach. In this protocol we describe selective ablation of rod photoreceptors in the premetamorphic Xenopus laevis retina using the nitroreductase/metronidazole (NTR/Mtz) system...
May 22, 2018: Cold Spring Harbor Protocols
Devin K Jones, Erika K Yates, Brian M Mattes, William D Hintz, Matthew S Schuler, Rick A Relyea
While the paradigm for increased tolerance to pesticides has been by selection on constitutive (naïve) traits, recent research has shown it can also occur through phenotypic plasticity. However, the time period in which induction can occur, the duration of induced tolerance, and the influence of multiple induction events remain unknown. We hypothesized that the induction of increased pesticide tolerance is limited to early sensitive periods, the magnitude of induced tolerance depends on the number of exposures, and the retention of induced tolerance depends on the time elapsed after an exposure and the number of exposures...
May 22, 2018: Environmental Toxicology and Chemistry
K Haydukivska, V Blavatska
We consider the complex polymer system, consisting of a ring polymer connected to the f_{1}-branched starlike structure, in a good solvent in the presence of structural inhomogeneities. In particular cases f_{1}=1 and f_{1}=2, such a system restores the synthesized tadpole-shaped polystyrenes [Doi et al., Macromolecules 46, 1075 (2013)MAMOBX0024-929710.1021/ma302511j]. We assume that structural defects are correlated at large distances x according to a power law x^{-a}. Applying the direct polymer renormalization approach, we evaluate the universal size characteristics such as the ratio of the radii of gyration of star-ring and star topologies, and compare the effective sizes of single arms in complex structures and isolated polymers of the same total molecular weight...
March 2018: Physical Review. E
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