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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
Yong Cui, Huiming Li, Sihui Wu, Runzhen Zhao, Deyi Du, Yan Ding, Hongguang Nie, Hong-Long Ji
Unsaturated oxidative formaldehyde is a noxious aldehyde in cigarette smoke that causes edematous acute lung injury. However, the mechanistic effects of formaldehyde on lung fluid transport are still poorly understood. We examined how formaldehyde regulates human epithelial sodium channels (ENaC) in H441 and expressed in Xenopus oocytes and exposed mice in vivo. Our results showed that formaldehyde reduced mouse transalveolar fluid clearance in vivo. Formaldehyde caused a dose-dependent inhibition of amiloride-sensitive short-circuit Na(+) currents in H441 monolayers and of αβγ-ENaC channel activity in oocytes...
October 20, 2016: Scientific Reports
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
Laurence D Picton, Keith T Sillar
Dopamine plays important roles in the development and modulation of motor control circuits. Here we show that dopamine exerts potent effects on the central pattern generator circuit controlling locomotory swimming in post-embryonic Xenopus tadpoles. Dopamine (0.5-100 μM) reduced fictive swim bout occurrence and caused both spontaneous and evoked episodes to become shorter, slower and weaker. The D2-like receptor agonist quinpirole mimicked this repertoire of inhibitory effects on swimming, whilst the D4 receptor antagonist, L745,870, had the opposite effects...
October 20, 2016: Scientific Reports
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
Cristina Matthewman, Tyne W Miller-Fleming, David M Miller, Laura Bianchi
Hyperactivated DEG/ENaC channels cause neuronal death mediated by intracellular Ca(2+) overload. Mammalian ASIC1a and C. elegans MEC-4(d) neurotoxic channels conduct both Na(+) and Ca(2+) raising the possibility that direct Ca(2+) influx through these channels contributes to the intracellular Ca(2+) overload. However, we showed that homologous C. elegans DEG/ENaC channel UNC-8(d) is not Ca(2+) permeable yet it is neurotoxic, suggesting that Na(+) influx is sufficient to induce cell death. Interestingly, UNC-8(d) shows small currents due to extracellular Ca(2+) block in the Xenopus oocytes expression system...
October 19, 2016: American Journal of Physiology. Cell Physiology
Fredrik Elinder, Michael Madeja, Hugo Zeberg, Peter Århem
The transmembrane voltage needed to open different voltage-gated K (Kv) channels differs by up to 50 mV from each other. In this study we test the hypothesis that the channels' voltage dependences to a large extent are set by charged amino-acid residues of the extracellular linkers of the Kv channels, which electrostatically affect the charged amino-acid residues of the voltage sensor S4. Extracellular cations shift the conductance-versus-voltage curve, G(V), by interfering with these extracellular charges...
October 18, 2016: Biophysical Journal
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
Mateusz Debowski, Mohammed El Dika, Jacek Malejczyk, Robert Zdanowski, Claude Prigent, Jean-Pierre Tassan, Malgorzata Kloc, Miroslaw Lachowicz, Jacek Z Kubiak
During the cell cycle, cyclin dependent kinase 1 (CDK1) and protein phosphatase 2A (PP2A) play major roles in the regulation of mitosis. CDK1 phosphorylates a series of substrates triggering M-phase entry. Most of these substrates are dephosphorylated by PP2A. To allow phosphorylation of CDK1 substrates, PP2A is progressively inactivated upon M-phase entry. We have shown previously that the interplay between these two activities determines the timing of M-phase entry. Slight diminution of CDK1 activity by the RO3306 inhibitor delays M-phase entry in a dose-dependent manner in Xenopus embryo cell-free extract, while reduction of PP2A activity by OA inhibitor accelerates this process also in a dose-dependent manner...
2016: International Journal of Developmental Biology
Predrag Jevtić, Ana Milunović-Jevtić, Matthew R Dilsaver, Jesse C Gatlin, Daniel L Levy
Striking size variations are prominent throughout biology, at the organismal, cellular, and subcellular levels. Important fundamental questions concern organelle size regulation and how organelle size is regulated relative to cell size, also known as scaling. Uncovering mechanisms of organelle size regulation will inform the functional significance of size as well as the implications of misregulated size, for instance in the case of nuclear enlargement in cancer. Xenopus egg and embryo extracts are powerful cell-free systems that have been utilized extensively for mechanistic and functional studies of various organelles and subcellular structures...
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
Jacek Z Kubiak, Claude Prigent
The aim of this short review is to describe the contribution of Xenopus laevis egg extracts to the discovery and understanding of the regulation and function of the serine/threonine kinase Aurora-A. The power of these extracts to recapitulate cell cycle events makes them a precious tool to decipher complex biological processes at the molecular level, including the mechanisms that affect Aurora-A (post-translational modifications) and mechanisms in which Aurora-A plays a crucial role (bipolar spindle assembly)...
2016: International Journal of Developmental Biology
Vincenzo Sannino, Arun M Kolinjivadi, Giorgio Baldi, Vincenzo Costanzo
The correct duplication of genetic information is essential to maintain genome stability, which is lost in cancer cells. Replication fork integrity is ensured by a number of DNA metabolism proteins that assist replication of chromatin regions difficult to replicate due to their intrinsic DNA sequence composition, coordinate repair of DNA molecules resulting from aberrant replication events or protect replication forks in the presence of lesions impairing their progression. Some DNA metabolism genes involved in DNA repair are essential in higher eukaryotes even in unchallenged conditions, suggesting the existence of biological processes requiring these specialized functions in organisms with complex genomes...
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
Wang Zheng, Jungwoo Yang, Erwan Beauchamp, Ruiqi Cai, Shaimaa Hussein, Laura Hofmann, Qiang Li, Veit Flockerzi, Luc G Berthiaume, Jingfeng Tang, Xing-Zhen Chen
Transient receptor potential polycystin-3 (TRPP3) is a cation channel activated by calcium and proton and is involved in hedgehog signaling, intestinal development, and sour tasting. How TRPP3 channel function is regulated remains poorly understood. By N-terminal truncation mutations, electrophysiology and Xenopus oocytes expression, we first identified fragment D21-S42 to be functionally important. We then found that deletion mutant Δ1-36 (TRPP3 missing fragment M1-R36) has similar function as wild-type TRPP3 while Δ1-38 is functionally dead, suggesting the importance of V37 or C38...
October 17, 2016: Journal of Biological Chemistry
Yosuke Nakazawa, Mikako Oka, Megumi Funakoshi-Tago, Hiroomi Tamura, Makoto Takehana
PURPOSE: Although aquaporin 0 (AQP0) is a member of the AQP family, it has limited water permeability compared with other members. AQP0 may also have cell adhesion-related functions, but the evidence is still limited. Here, we studied the relationship of AQP0 to cell adhesion and determined the region required for cell adhesion. METHODS: L-cell fibroblasts stably expressing AQP0 or AQP1 (L-AQP0 or L-AQP1) were established. One group of cells was stained with CellTracker Red and cultured into a confluent monolayer, whereas the other group was loaded with CellTracker Blue and seeded over the monolayer...
October 18, 2016: Current Eye Research
Anahita Nourmahnad, Alex T Stern, Mayo Hotta, Deirdre S Stewart, Alexis M Ziemba, Andrea Szabo, Stuart A Forman
BACKGROUND: γ-Aminobutyric acid type A (GABAA) receptors mediate important effects of intravenous general anesthetics. Photolabel derivatives of etomidate, propofol, barbiturates, and a neurosteroid get incorporated in GABAA receptor transmembrane helices M1 and M3 adjacent to intersubunit pockets. However, photolabels have not been consistently targeted at heteromeric αβγ receptors and do not form adducts with all contact residues. Complementary approaches may further define anesthetic sites in typical GABAA receptors...
October 7, 2016: Anesthesiology
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
Xiuhong Cai, Xiang Li, Hong Qi, Fang Wei, Jianyong Chen, Jianwei Shuai
The gating properties of the inositol 1, 4, 5-trisphosphate (IP3) receptor (IP3R) are determined by the binding and unbinding capability of Ca(2+) ions and IP3 messengers. With the patch clamp experiments, the stationary properties have been discussed for Xenopus oocyte type-1 IP3R (Oo-IP3R1), type-3 IP3R (Oo-IP3R3) and Spodoptera frugiperda IP3R (Sf-IP3R). In this paper, in order to provide insights about the relation between the observed gating characteristics and the gating parameters in different IP3Rs, we apply the immune algorithm to fit the parameters of a modified DeYoung-Keizer model...
October 17, 2016: Physical Biology
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
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