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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
Luca Fusi, Valentina Percario, Elisabetta Brunello, Marco Caremani, Pasquale Bianco, Joseph D Powers, Massimo Reconditi, Vincenzo Lombardi, Gabriella Piazzesi
KEY POINTS: Myosin filament mechanosensing determines the efficiency of the contraction by adapting the number of switched ON motors to the load. Accordingly, the unloaded shortening velocity (V0 ) is already set at the end of the latency relaxation (LR), ∼10 ms after the start of stimulation, when the myosin filament is still in the OFF state. Here the number of actin-attached motors per half-myosin filament (n) during V0 shortening imposed either at the end of LR or at the plateau of the isometric contraction is estimated from the relation between half-sarcomere compliance and force during the force redevelopment after the shortening...
October 20, 2016: Journal of Physiology
Shawn Burgess
No abstract text is available yet for this article.
October 19, 2016: Nature
Adam M Session, Yoshinobu Uno, Taejoon Kwon, Jarrod A Chapman, Atsushi Toyoda, Shuji Takahashi, Akimasa Fukui, Akira Hikosaka, Atsushi Suzuki, Mariko Kondo, Simon J van Heeringen, Ian Quigley, Sven Heinz, Hajime Ogino, Haruki Ochi, Uffe Hellsten, Jessica B Lyons, Oleg Simakov, Nicholas Putnam, Jonathan Stites, Yoko Kuroki, Toshiaki Tanaka, Tatsuo Michiue, Minoru Watanabe, Ozren Bogdanovic, Ryan Lister, Georgios Georgiou, Sarita S Paranjpe, Ila van Kruijsbergen, Shengquiang Shu, Joseph Carlson, Tsutomu Kinoshita, Yuko Ohta, Shuuji Mawaribuchi, Jerry Jenkins, Jane Grimwood, Jeremy Schmutz, Therese Mitros, Sahar V Mozaffari, Yutaka Suzuki, Yoshikazu Haramoto, Takamasa S Yamamoto, Chiyo Takagi, Rebecca Heald, Kelly Miller, Christian Haudenschild, Jacob Kitzman, Takuya Nakayama, Yumi Izutsu, Jacques Robert, Joshua Fortriede, Kevin Burns, Vaneet Lotay, Kamran Karimi, Yuuri Yasuoka, Darwin S Dichmann, Martin F Flajnik, Douglas W Houston, Jay Shendure, Louis DuPasquier, Peter D Vize, Aaron M Zorn, Michihiko Ito, Edward M Marcotte, John B Wallingford, Yuzuru Ito, Makoto Asashima, Naoto Ueno, Yoichi Matsuda, Gert Jan C Veenstra, Asao Fujiyama, Richard M Harland, Masanori Taira, Daniel S Rokhsar
To explore the origins and consequences of tetraploidy in the African clawed frog, we sequenced the Xenopus laevis genome and compared it to the related diploid X. tropicalis genome. We characterize the allotetraploid origin of X. laevis by partitioning its genome into two homoeologous subgenomes, marked by distinct families of 'fossil' transposable elements. On the basis of the activity of these elements and the age of hundreds of unitary pseudogenes, we estimate that the two diploid progenitor species diverged around 34 million years ago (Ma) and combined to form an allotetraploid around 17-18 Ma...
October 19, 2016: Nature
Camille Lombard-Banek, Sally A Moody, Peter Nemes
Direct measurement of protein expression with single-cell resolution promises to deepen the understanding of the basic molecular processes during normal and impaired development. High-resolution mass spectrometry provides detailed coverage of the proteomic composition of large numbers of cells. Here we discuss recent mass spectrometry developments based on single-cell capillary electrophoresis that extend discovery proteomics to sufficient sensitivity to enable the measurement of proteins in single cells. The single-cell mass spectrometry system is used to detect a large number of proteins in single embryonic cells in the 16-cell embryo of the South African clawed frog (Xenopus laevis) that give rise to distinct tissue types...
2016: Frontiers in Cell and Developmental Biology
Ayako Yamaguchi, Jessica Cavin Barnes, Todd Appleby
Central pattern generators (CPG) in the brainstem are considered to underlie vocalizations in many vertebrate species, but the detailed mechanisms underlying how motor rhythms are generated, coordinated, and initiated remain unclear. We addressed these issues using isolated brain preparations of Xenopus laevis from which fictive vocalizations can be elicited. Advertisement calls of male X. laevis that consist of fast and slow trills are generated by vocal CPGs contained in the brainstem. Brainstem central vocal pathways consist of a premotor nucleus (DTAM) and a laryngeal motor nucleus (n...
October 19, 2016: Journal of Neurophysiology
Wei-Lin Wang, David Shechter
Chromatin, primarily a complex of DNA and histone proteins, is the physiological form of the genome. Chromatin is generally repressive for transcription and other information transactions that occur on DNA. A wealth of post-translational modifications on canonical histones and histone variants encode regulatory information to recruit or repel effector proteins on chromatin, promoting and further repressing transcription and thereby form the basis of epigenetic information. During metazoan oogenesis, large quantities of histone proteins are synthesized and stored in preparation for the rapid early cell cycles of development and to elicit maternal control of chromatin assembly pathways...
2016: International Journal of Developmental Biology
Takashi Onikubo, David Shechter
Chromatin is the complex of DNA and histone proteins that is the physiological form of the eukaryotic genome. Chromatin is generally repressive for transcription, especially so during early metazoan development when maternal factors are explicitly in control of new zygotic gene expression. In the important model organism Xenopus laevis, maturing oocytes are transcriptionally active with reduced rates of chromatin assembly, while laid eggs and fertilized embryos have robust rates of chromatin assembly and are transcriptionally repressed...
2016: International Journal of Developmental Biology
J Julian Blow, Ronald A Laskey
Here we discuss the important contributions that cell-free extracts have made to the study of complex biological processes. We provide a brief history of how cell-free extracts of frog eggs were developed to avoid many of the problems that can arise from the dilution and mixing of cellular components that typically occur when cell-free extracts are prepared. We briefly describe how Xenopus egg extracts have been fundamental to the study of many important cellular processes including DNA replication, cell cycle progression, nuclear protein import, nuclear assembly and chromosome organisation...
2016: International Journal of Developmental Biology
Fathy Abdel-Ghaffar, Rewaida Abdel-Gaber, Sherein Maher, Nashwa El Deeb, Reem Kamel, Saleh Al Quraishy, Heinz Mehlhorn
Myxozoans are one of the most economically important groups of protozoan parasites causing many serious diseases of their hosts. In the present study, a total of 60 live adult male specimens of the marsh frog Rana ridibunda have been randomly captured during the period of January-December 2015 in different areas at Kafr El-Sheikh Governorate, Egypt and were examined for infection by myxosporidian parasites. A total of 48 (80.0 %) out of 60 frog specimens were found to be infected with Myxobolus species. Parasitic infection was restricted to the testicular tissue of the examined frogs...
October 19, 2016: Parasitology Research
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
Po-Ya Wu, Hsuan-Hao Lu, Ching-Zhe Weng, Yen-Hung Chen, Shang-Da Yang
The phase retrieval algorithm of a frequency-resolved optical gating (FROG) is generalized to handle traces seriously distorted by group delay dispersion and non-uniform phase-matching spectra arising from the nonlinear crystal. In our proof-of-concept experiments, 15 mm thick aperiodically poled lithium niobate was employed in FROG, and successfully reconstructed chirped signal pulses were actually stretched by >5 times inside the crystal. This method is particularly promising in the measurement of weak few-cycle pulses produced by supercontinuum generation in fibers...
October 1, 2016: Optics Letters
Michela De Bellis, Roberta Carbonara, Julien Roussel, Alessandro Farinato, Ada Massari, Sabata Pierno, Marilena Muraglia, Filomena Corbo, Carlo Franchini, Maria Rosaria Carratù, Annamaria De Luca, Diana Conte Camerino, Jean-François Desaphy
Although the sodium channel blocker, mexiletine, is the first choice drug in myotonia, some myotonic patients remain unsatisfied due to contraindications, lack of tolerability, or incomplete response. More therapeutic options are thus needed for myotonic patients, which require clinical trials based on solid preclinical data. In previous structure-activity relationship studies, we identified two newly-synthesized derivatives of tocainide, To040 and To042, with greatly enhanced potency and use-dependent behavior in inhibiting sodium currents in frog skeletal muscle fibers...
October 12, 2016: Neuropharmacology
Elisa Rota, Gianfranco Tanteri, Gilberto Montori, Filippo Giachi, Giovanni Delfino, David M Sever
Several anuran species of the genus Phyllomedusa are known to possess specialized cutaneous glands producing lipids and exhibit a peculiar wiping behavior. This behavior is a stereotyped repertory of fore and hind limb movements distributing hydrophobic molecules onto the body surface and reducing evaporative water loss. No reports are presently available on the occurrence of lipid glands in other phyllomedusine genera, and data on the structure of the secretory units specialized for the production of cutaneous lipids are still unclear...
October 14, 2016: Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology
Tainã Rapp Py-Daniel, Anderson Kennedy Soares De-Lima, Fabiano Campos Lima, Aline Pic-Taylor, Osmindo Rodrigues Pires Junior, Antonio Sebben
The mouse, chicken, African clawed frog and zebrafish are considered "model organisms" due to their extensive embryological and genetic characterization. However they are far from representative of known diversity, impairing phylogenetic analyses of developmental patterns. Since squamates have historically received limited attention in developmental studies, we here describe the developmental sequence for Tropidurus torquatus, and provide the first post-ovipositional developmental series for the lizard family Tropiduridae...
October 14, 2016: Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology
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
Mark A Bee, Jakob Christensen-Dalsgaard
Acoustic signaling plays key roles in mediating many of the reproductive and social behaviors of anurans (frogs and toads). Moreover, acoustic signaling often occurs at night, in structurally complex habitats, such as densely vegetated ponds, and in dense breeding choruses characterized by high levels of background noise and acoustic clutter. Fundamental to anuran behavior is the ability of the auditory system to determine accurately the location from where sounds originate in space (sound source localization) and to assign specific sounds in the complex acoustic milieu of a chorus to their correct sources (sound source segregation)...
October 12, 2016: Biological Cybernetics
Damien A Fordham, Barry W Brook, Conrad J Hoskin, Robert L Pressey, Jeremy VanDerWal, Stephen E Williams
The effect of twenty-first-century climate change on biodiversity is commonly forecast based on modelled shifts in species ranges, linked to habitat suitability. These projections have been coupled with species-area relationships (SAR) to infer extinction rates indirectly as a result of the loss of climatically suitable areas and associated habitat. This approach does not model population dynamics explicitly, and so accepts that extinctions might occur after substantial (but unknown) delays-an extinction debt...
October 2016: Biology Letters
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