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Sanam Zarei, Kasra Zarei, Bernd Fritzsch, Karen L Elliott
Sonic Hedgehog (Shh) signaling plays a major role in vertebrate development, from regulation of proliferation to the patterning of various organs. In amniotes, Shh affects dorsoventral patterning in the inner ear but affects anteroposterior patterning in teleosts. Currently, it remains unknown the function of Shh in inner ear development in terms of how morphogenesis changes in the sarcopterygian/tetrapod lineage coincide with the evolution of limbs and novel auditory organs in the ear. In this study we used the tetrapod, Xenopus laevis, to test how increasing concentrations of the Shh signal pathway antagonist, Vismodegib, affects ear development...
October 14, 2017: Developmental Neurobiology
Sarah A Knutie, Caitlin Gabor, Kevin D Kohl, Jason R Rohr
1.Environmental stressors, such as pollutants, can increase disease risk in wildlife. For example, the herbicide atrazine affects host defenses (e.g. resistance and tolerance) of the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd), but the mechanisms for these associations are not always clear. Given that pollutants can alter the gut microbiota of hosts, which in turn can affect their health and immune systems, one potential mechanism by which pollutants could increase infection risk is by influencing host-associated microbiota...
October 14, 2017: Journal of Animal Ecology
Jonathan Zerweck, Erik Strandberg, Olga Kukharenko, Johannes Reichert, Jochen Bürck, Parvesh Wadhwani, Anne S Ulrich
PGLa and magainin 2 (MAG2) are amphiphilic α-helical membranolytic peptides from frog skin with known synergistic antimicrobial activity. By systematically mutating residues in the two peptides it was possible to identify the ones crucial for the synergy, as monitored by biological assays, fluorescence vesicle leakage, and solid-state (15)N-NMR. Electrostatic interactions between anionic groups in MAG2 and cationic residues in PGLa enhance synergy but are not necessary for the synergistic effect. Instead, two Gly residues (7 and 11) in a so-called GxxxG motif in PGLa are necessary for synergy...
October 13, 2017: Scientific Reports
Tyler D Hoskins, Michelle D Boone
We exposed Blanchard's cricket frogs (Acris blanchardi) to ecologically relevant concentrations (0, 0.1, 1, and 10 μg/L) of a commercial formulation of atrazine throughout the larval period to determine effects on survival, somatic growth and development (time to metamorphosis and mass at metamorphosis), and gonadal development (sex ratio at metamorphosis and the prevalence of testicular ova in phenotypic males). We tested the following hypotheses: 1) atrazine feminizes the sex ratio, 2) atrazine increases the proportion of phenotypic males with testicular ova, and 3) atrazine differentially affects somatic growth (mass at metamorphosis) and development (time to metamorphosis) for males and females...
October 13, 2017: Environmental Toxicology and Chemistry
Krzysztof Kowalski, Paweł Marciniak, Grzegorz Rosiński, Leszek Rychlik
BACKGROUND: Animal toxins can have medical and therapeutic applications. Principally, toxins produced by insects, arachnids, snakes and frogs have been characterized. Venomous mammals are rare, and their venoms have not been comprehensively investigated. Among shrews, only the venom of Blarina brevicauda has been analysed so far, and blarina toxin has been proven to be its main toxic component. It is assumed that Neomys fodiens employs its venom to hunt larger prey. However, the toxic profile, properties and mode of action of its venom are largely unknown...
2017: Frontiers in Zoology
Faget-Agius Catherine, Vincenti Aurélie, Guedj Eric, Michel Pierre, Richieri Raphaëlle, Alessandrini Marine, Auquier Pascal, Lançon Christophe, Boyer Laurent
This study aims to define functioning levels of patients with schizophrenia by using a method of interpretable clustering based on a specific functioning scale, the Functional Remission Of General Schizophrenia (FROGS) scale, and to test their validity regarding clinical and neuroimaging characterization. In this observational study, patients with schizophrenia have been classified using a hierarchical top-down method called clustering using unsupervised binary trees (CUBT). Socio-demographic, clinical, and neuroimaging SPECT perfusion data were compared between the different clusters to ensure their clinical relevance...
September 8, 2017: Psychiatry Research
Jon T Sack
Toxins are the poisonous products of organisms. Toxins serve vital defensive and offensive functions for those that harbor them: stinging scorpions, pesticidal plants, sanguinary snakes, fearless frogs, sliming snails, noxious newts, and smarting spiders. For physiologists, toxins are integral chemical tools that hijack life's fundamental processes with remarkable molecular specificity. Our understanding of electrophysiological phenomena has been transformed time and time again with the help of some terrifying toxins...
October 11, 2017: Journal of General Physiology
Jérémy Tissier, Jean-Claude Rage, Michel Laurin
Fossils are almost always represented by hard tissues but we present here the exceptional case of a three-dimensionally preserved specimen that was 'mummified' (likely between 40 and 34 million years ago) in a terrestrial karstic environment. This fossil is the incomplete body of a salamander, Phosphotriton sigei, whose skeleton and external morphology are well preserved, as revealed by phase-contrast synchrotron X-ray microtomography. In addition, internal structures composed of soft tissues preserved in three dimensions are now identified: a lung, the spinal cord, a lumbosacral plexus, the digestive tract, muscles and urogenital organs that may be cloacal glands...
2017: PeerJ
Yuya Nakai, Keisuke Nakajima, Yoshio Yaoita
Tail regression in amphibian tadpoles during metamorphosis is one of the most dynamic morphological changes in animal development and is induced by thyroid hormone (TH). It has been proposed that tail resorption is driven by immunological rejection in Xenopus laevis, based on experimental evidence showing that larval skin grafts become atrophic on syngenic recipient adult frogs. This led to the hypothesis that tail regression is induced by an immunological rejection against larval skin-specific antigens called Ouro proteins...
October 2017: Zoological Science
Lisa A Mangiamele, Matthew J Fuxjager
A hallmark of sexual selection is the evolution of elaborate male sexual signals. Yet, how the physiology of an animal changes to support a new or modified signal is a question that has remained largely unanswered. Androgens are important in regulating male reproductive behavior, therefore, selection for particular signals may drive the evolution of increased androgenic sensitivity in the neuro-motor systems underlying their production. Studies of the neuroendocrine mechanisms of anuran sexual signaling provide evidence to support this idea...
October 7, 2017: Journal of Comparative Physiology. A, Neuroethology, Sensory, Neural, and Behavioral Physiology
Sylvain Dubey, Christophe Dufresnes
Hybridogenesis is a special mode of hybrid reproduction where one parental genome is eliminated and the other is transmitted clonally. We propose that this mechanism can perpetuate the genome of extinct species, based on new genetic data from Pelophylax water frogs. We characterized the genetic makeup of Italian hybridogenetic hybrids (P. kl. hispanicus and esculentus) and identified a new endemic lineage of Eastern-Mediterranean origin as one parental ancestor of P. kl. hispanicus. This taxon is nowadays extinct in the wild but its germline subsists through its hybridogenetic descendant, which can thus be considered as a "semi living fossil"...
October 6, 2017: Scientific Reports
Robin W Warne, Lucas Kirschman, Lydia Zeglin
Exploration of the importance of developmental windows for microbial colonization in diverse animal taxa, and tests of how these shape both animal microbiomes as well as host phenotypes promise to shed needed light on host-microbe interactions. The aims of this study were to explore how gut microbiota diversity of larval amphibians varies among species and across ontogeny, and to test if manipulation of gut colonization can reveal how microbiomes develop. We found that gut microbiomes differ among species and change across larval ontogeny, with distinctive differences between larvae, metamorphic animals, and juvenile frogs...
July 26, 2017: Integrative and Comparative Biology
Esteban Vargas Bernal, Camilo Sanabria Malagon
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...
October 5, 2017: Bulletin of Mathematical Biology
Aude Anzeraey, Madeleine Aumont, Thierry Decamps, Anthony Herrel, Emmanuelle Pouydebat
The ability to grasp an object is fundamental from an evolutionary perspective. Involved in many daily activities, grasping has been extensively studied in primates and other mammals. Yet, other groups of tetrapods, including anurans, have also evolved significant forelimb prehensile capacities that are often thought to have originated in an arboreal context. However, grasping is also observed in aquatic species. Yet, how aquatic frogs use their forelimbs to capture and manipulate prey remains largely unknown...
October 5, 2017: Journal of Experimental Biology
A Kroth, V Mackedanz, C Matté, A T S Wyse, M F M Ribeiro, W A Partata
Sciatic nerve transection (SNT), a model for studying neuropathic pain, mimics the clinical symptoms of "phantom limb", a pain condition that arises in humans after amputation or transverse spinal lesions. In some vertebrate tissues, this condition decreases acetylcholinesterase (AChE) activity, the enzyme responsible for fast hydrolysis of released acetylcholine in cholinergic synapses. In spinal cord of frog Rana pipiens, this enzyme's activity was not significantly changed in the first days following ventral root transection, another model for studying neuropathic pain...
September 28, 2017: Brazilian Journal of Biology, Revista Brasleira de Biologia
Michele Menegon, Chiara Cantaloni, Ana Rodriguez-Prieto, Cesare Centomo, Ahmed Abdelfattah, Marzia Rossato, Massimo Bernardi, Luciano Xumerle, Simon Loader, Massimo Delledonne
Biodiversity research is becoming increasingly dependent on genomics, which allows the unprecedented digitization and understanding of the planet's biological heritage. The use of genetic markers i.e. DNA barcoding, has proved to be a powerful tool in species identification. However, full exploitation of this approach is hampered by the high sequencing costs and the absence of equipped facilities in biodiversity-rich countries. In the present work, we developed a portable sequencing laboratory based on the portable DNA sequencer from Oxford Nanopore Technologies, the MinION...
2017: PloS One
Wen Bo Liao, Yan Huang, Yu Zeng, Mao Jun Zhong, Yi Luo, Stefan Lüpold
The evolution of sperm quality and quantity is shaped by various selective processes, with sperm competition generally considered the primary selective agent. Particularly in external fertilizers, however, sperm limitation through gamete dispersal can also influence gamete investments, but empirical data examining this effect are limited. Here, we studied the relative importance of sperm competition and the spawning conditions in explaining the macroevolutionary patterns of sperm size and number within two taxa with external fertilization but differences in their reproductive biology...
October 4, 2017: Evolution; International Journal of Organic Evolution
Svetlana Deryusheva, Joseph G Gall
The branch point recognition region of spliceosomal snRNA U2 is heavily modified post-transcriptionally in most eukaryotic species. We focused on this region to learn how nearby positions may interfere with each other when targeted for modification. Using an in vivo yeast Saccharomyces cerevisiae cell system we tested modification activity of several guide RNAs from human, mouse, the frog Xenopus tropicalis, the fruit fly Drosophila melanogaster and the worm Caenorhabditis elegans. We experimentally verified predictions for vertebrate U2 modification guide RNAs SCARNA4 and SCARNA15, and identified a C...
September 29, 2017: RNA
Kurt R Venator, Michael J Ryan, Walter Wilczynski
We examined the vocal and non-vocal responses of male cricket frogs (Acris crepitans) to conspecific advertisement calls that had been attenuated or degraded by reducing the depth of amplitude modulation (AM). Both are characteristic of changes to the call as it is transmitted through natural habitats. As stimulus calls became more intense or less degraded, male cricket frogs gradually decreased their call rate and increased the number of call groups and pulse groups in their calls, changes indicative of increased aggressive interactions...
May 2017: Ethology: Formerly Zeitschrift Für Tierpsychologie
Petia Kupenova, Elka Popova, Liliya Vitanova
The contribution of the purinergic receptors P2X7 (P2X7Rs) to the electroretinographic (ERG) responses was studied by testing the effects of the selective P2X7R antagonist A438079 and the selective P2X7R agonist Bz-ATP on the electroretinograms obtained in perfused frog (Rana ridibunda) eyecup preparations under a variety of stimulation conditions. The P2X7R blockade by 200 µM A438079 diminished the amplitude of the photoreceptor components: the a-wave and the pharmacologically isolated mass receptor potential...
January 2017: Visual Neuroscience
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