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Andrei Tsentsevitsky, Leniz Nurullin, Evgeny Nikolsky, Artem Malomouzh
There is some evidence that glutamate (Glu) acts as a signaling molecule at vertebrate neuromuscular junctions where acetylcholine (ACh) serves as a neurotransmitter. In this study, performed on the cutaneous pectoris muscle of the frog Rana ridibunda, Glu receptor mechanisms that modulate ACh release processes were analyzed. Electrophysiological experiments showed that Glu reduces both spontaneous and evoked quantal secretion of ACh and synchronizes its release in response to electrical stimulation. Quisqualate, an agonist of ionotropic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic receptors and metabotropic Group I mGlu receptors, also exerted Glu-like inhibitory effects on the secretion of ACh but had no effect on the kinetics of quantal release...
October 22, 2016: Journal of Neuroscience Research
Thomas Pannicke, T Ivo Chao, Miriam Reisenhofer, Mike Francke, Andreas Reichenbach
Müller cells are the dominant macroglial cells in the retina of all vertebrates. They fulfill a variety of functions important for retinal physiology, among them spatial buffering of K(+) ions and uptake of glutamate and other neurotransmitters. To this end, Müller cells express inwardly rectifying K(+) channels and electrogenic glutamate transporters. Moreover, a lot of voltage- and ligand-gated ion channels, aquaporin water channels, and electrogenic transporters are expressed in Müller cells, some of them in a species-specific manner...
October 21, 2016: Glia
Dariusz Wodziak, Aiwen Dong, Michael F Basin, Anson W Lowe
A recently published study identified Anterior Gradient 2 (AGR2) as a regulator of EGFR signaling by promoting receptor presentation from the endoplasmic reticulum to the cell surface. AGR2 also promotes tissue regeneration in amphibians and fish. Whether AGR2-induced EGFR signaling is essential for tissue regeneration in higher vertebrates was evaluated using a well-characterized murine model for pancreatitis. The impact of AGR2 expression and EGFR signaling on tissue regeneration was evaluated using the caerulein-induced pancreatitis mouse model...
2016: PloS One
Irina Trofimova, Alla Krasikova
Tandemly organized highly repetitive DNA sequences are crucial structural and functional elements of eukaryotic genomes. Despite extensive evidence, satellite DNA remains an enigmatic part of the eukaryotic genome, with biological role and significance of tandem repeat transcripts remaining rather obscure. Data on tandem repeats transcription in amphibian and avian model organisms is fragmentary despite their genomes being thoroughly characterized. Review systematically covers historical and modern data on transcription of amphibian and avian satellite DNA in somatic cells and during meiosis when chromosomes acquire special lampbrush form...
October 20, 2016: RNA Biology
Garrett J McKinney, Ryan K Waples, Lisa W Seeb, James E Seeb
Whole genome duplications have occurred in the recent ancestors of many plants, fish, and amphibians, resulting in a pervasiveness of paralogous loci and the potential for both disomic and tetrasomic inheritance in the same genome. Paralogs can be difficult to reliably genotype and are often excluded from genotyping-by-sequencing (GBS) analyses; however, removal requires paralogs to be identified which is difficult without a reference genome. We present a method for identifying paralogs in natural populations by combining two properties of duplicated loci: 1) the expected frequency of heterozygotes exceeds that for singleton loci, and 2) within heterozygotes, observed read ratios for each allele in GBS data will deviate from the 1:1 expected for singleton (diploid) loci...
October 19, 2016: Molecular Ecology Resources
Alberto Muñoz, Xavier Santos, Ángel M Felicísimo
Ecological Niche Models (ENMs) are widely used to describe how environmental factors influence species distribution. Modelling at a local scale, compared to a large scale within a high environmental gradient, can improve our understanding of ecological species niches. The main goal of this study is to assess and compare the contribution of environmental variables to amphibian and reptile ENMs in two Spanish national parks located in contrasting biogeographic regions, i.e., the Mediterranean and the Atlantic area...
2016: PeerJ
Scott M Weir, David E Scott, Christopher J Salice, Stacey L Lance
Chemical contamination is often suggested as an important contributing factor to amphibian population declines, but direct links are rarely reported. Population modeling provides a quantitative method to integrate toxicity data with demographic data to understand the long-term effects of contaminants on population persistence. In this study we use laboratory-derived embryo and larval toxicity data for two anuran species to investigate the potential for toxicity to contribute to population declines. We use the southern toad (Anaxyrus terrestris) and the southern leopard frog (Lithobates sphenocephalus) as model species to investigate copper (Cu) toxicity...
September 2016: Ecological Applications: a Publication of the Ecological Society of America
Annette Aldrich, Marion Junghans, Caroline Aeberli, Carsten A Brühl, Franz Streissl, Benedikt R Schmidt
BACKGROUND: The majority of Swiss amphibians are threatened. There is a range of factors which have been discussed as possible causes for their decline, including plant protection products (PPPs). RESULTS: The influence of PPPs on amphibian populations has not yet been studied to any great extent, neither for active ingredients nor for the wetting agents, breakdown products or tank mixtures. A further topic of discussion was how to better protect amphibians by reducing their exposure to PPPs in agricultural fields...
2016: Environmental Sciences Europe
Katharina Kaufmann, Peter Dohmen
BACKGROUND: Literature data indicate that terrestrial life stages of amphibians may be more sensitive to xenobiotics than birds or mammals. It is hypothesized that dermal exposure could potentially be a significant route of exposure for amphibians, as there is evidence that their skin is more permeable than the skin of other vertebrate species. Thus, higher amounts of xenobiotics might enter systemic circulation by dermal uptake resulting in adverse effects. Heretofore, no guidelines exist to investigate dermal toxicity of chemicals to amphibians...
2016: Environmental Sciences Europe
Cody S Shirriff, John J Heikkila
Endoplasmic reticulum (ER) stress can result in the accumulation of unfolded/misfolded protein in the ER lumen, which can trigger the unfolded protein response (UPR) resulting in the activation of various genes including immunoglobulin-binding protein (BiP; also known as glucose-regulated protein 78 or HSPA5). BiP, an ER heat shock protein 70 (HSP70) family member, binds to unfolded protein, inhibits their aggregation and re-folds them in an ATP-dependent manner. While cadmium, an environmental contaminant, was shown to induce the accumulation of HSP70 in vertebrate cells, less information is available regarding the effect of this metal on BiP accumulation or function...
October 13, 2016: Comparative Biochemistry and Physiology. Toxicology & Pharmacology: CBP
M J Madison-Villar, Cheng Sun, Nelson C Lau, Matthew L Settles, Rachel Lockridge Mueller
Most of the largest vertebrate genomes are found in salamanders, a clade of amphibians that includes 686 species. Salamander genomes range in size from 14 to 120 Gb, reflecting the accumulation of large numbers of transposable element (TE) sequences from all three TE classes. Although DNA loss rates are slow in salamanders relative to other vertebrates, high levels of TE insertion are also likely required to explain such high TE loads. Across the Tree of Life, novel TE insertions are suppressed by several pathways involving small RNA molecules...
October 14, 2016: Journal of Molecular Evolution
Kristin Mühldorfer, Gudrun Wibbelt, Claudia A Szentiks, Dominik Fischer, Holger C Scholz, Michael Zschöck, Tobias Eisenberg
AIMS: Novel cases of Brucella infections in frogs are discussed together with results of published reports to extend our current knowledge on 'atypical' brucellae isolated from amphibians and discuss challenges we face on this extraordinary emerging group of pathogens. METHODS AND RESULTS: Since our first description, additional 14 isolates from 4 different frog species were collected. Novel isolates and a subset of Brucella isolates previously cultured from African bullfrogs were characterized by MALDI-TOF mass spectrometry, Fourier transform-infrared spectroscopy and broth microdilution susceptibility testing...
October 14, 2016: Journal of Applied Microbiology
Pedro F Soler-Lloréns, Chris R Quance, Sara D Lawhon, Tod P Stuber, John F Edwards, Thomas A Ficht, Suelee Robbe-Austerman, David O'Callaghan, Anne Keriel
Brucella are highly infectious bacterial pathogens responsible for brucellosis, a frequent worldwide zoonosis. The Brucella genus has recently expanded from 6 to 11 species, all of which were associated with mammals; The natural host range recently expanded to amphibians after some reports of atypical strains from frogs. Here we describe the first in depth phenotypic and genetic characterization of a Brucella strains isolated from a frog. Strain B13-0095 was isolated from a Pac-Man frog (Ceratophyrus ornate) at a veterinary hospital in Texas and was initially misidentified as Ochrobactrum anthropi...
2016: Frontiers in Cellular and Infection Microbiology
Jeffrey R Row, Michael E Donaldson, Jessica N Longhi, Barry J Saville, Dennis L Murray
A potential cause of amphibian population declines are the impacts of environmental degradation on tadpole development. We conducted RNA sequencing on developing northern leopard frog tadpoles and through de novo transcriptome assembly we annotated a large number of open reading frames comparable in number and extent to genes identified in Xenopus. Using our transcriptome, we found transcript level changes between early (Gosner 26-31) and late (Gosner 36-41) stage tadpoles were the greatest in the tail, which is reabsorbed throughout development...
October 11, 2016: Genomics
Vanessa A Mendes, Katia C Barbaro, Juliana M Sciani, Ruth C Vassão, Daniel C Pimenta, Carlos Jared, Marta M Antoniazzi
Corythomantis greeningi is a tree-frog endemic of the Brazilian semi-arid (Caatinga), mainly characterized by the flat, mineralized and spiny head, which is associated with phragmotic habits. It is already known that the skin secretion of this amphibian from both head and body is quite toxic and is used as an efficient chemical defence against predators. However, the biochemical characteristics and pharmacological effects of this secretion are still very little studied. We have tested the crude skin secretion, as well as the ten major fractions obtained by RP-HPLC for nociceptive and edema activity and for in vitro cytotoxicity using murine models...
October 5, 2016: Toxicon: Official Journal of the International Society on Toxinology
Freya E Rowland, Madelyn B Rawlings, Raymond D Semlitsch
Primary production can be controlled through bottom-up (e.g., resources) or top-down (e.g., predators) constraints. Two key bottom-up resources in small aquatic systems are light and nutrients, and forest canopy cover heavily influences these factors, whereas amphibian and invertebrate colonizers exert top-down pressure as grazers and predators. We designed our experiment to specifically manipulate two different top-down and bottom-up factors. We manipulated resources by altering light (low/high) and nutrient (low/high) availability; omnivores with the presence/absence of southern leopard frog tadpoles (Lithobates sphenocephalus); and predators with the presence/absence of spotted salamander larvae (Ambystoma maculatum) in a full-factorial experiment conducted over 14 weeks...
October 7, 2016: Oecologia
Enikő Fehér, Andor Doszpoly, Balázs Horváth, Szilvia Marton, Barbara Forró, Szilvia L Farkas, Krisztián Bányai, Tamás Juhász
Ranaviruses are emerging pathogens associated with high mortality diseases in fish, amphibians and reptiles. Here we describe the whole genome sequence of two ranavirus isolates from brown bullhead (Ameiurus nebulosus) specimens collected in 2012 at two different locations in Hungary during independent mass mortality events. The two Hungarian isolates were highly similar to each other at the genome sequence level (99.9% nucleotide identity) and to a European sheatfish (Silurus glanis) origin ranavirus (ESV, 99...
October 4, 2016: Infection, Genetics and Evolution
S Veron, P Clergeau, S Pavoine
BACKGROUND: Phylogenetic diversity and evolutionary distinctiveness are highly valuable components of biodiversity, but they are rarely considered in conservation practices. Focusing on a biodiversity hotspot, the Mediterranean Basin, we aimed to identify those areas where evolutionary history is highly threatened and range-restricted in the region. Using null models, we first compared the spatial distributions of three indices: two measured threatened evolutionary history-Expected PDloss and Heightened Evolutionary distinctiveness and Global Endangerment-and one measured endemic evolutionary history-Biogeographically Evolutionary Distinctiveness...
October 7, 2016: BMC Ecology
Weizhao Yang, Yin Qi, Jinzhong Fu
BACKGROUND: High-altitude adaptation provides an excellent system for studying how organisms cope with multiple environmental stressors and interacting genetic modifications. To explore the genetic basis of high-altitude adaptation in poikilothermic animals, we acquired transcriptome sequences from a high-altitude population and a low-altitude population of the Asiatic toad (Bufo gargarizans). Transcriptome data from another high-altitude amphibian, Rana kukunoris and its low-altitude relative R...
October 3, 2016: BMC Genetics
April L Bagwill, Matthew B Lovern, Thomas A Worthington, Loren M Smith, Scott T McMurry
Amphibian metamorphosis is complex and larval morphology and physiology are completely restructured during this time. Amphibians that live in unpredictable environments are often exposed to stressors that can directly and indirectly alter physiological systems during development, with subsequent consequences (carryover effects) later in life. In this study, we investigated the effects of water level reduction on development rate, spleen size and cellularity, and examined the role of corticosterone levels in premetamorphic, metamorphic, and postmetamorphic New Mexico spadefoot toads (Spea multiplicata)...
October 6, 2016: Journal of Experimental Zoology. Part A, Ecological Genetics and Physiology
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