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Parthena Soupiadou, Francisco Branoner, Hans Straka
Vestibulo-ocular reflexes (VOR) are mediated by three-neuronal brainstem pathways that transform semicircular canal and otolith sensory signals into motor commands for the contraction of spatially specific sets of eye muscles. The vestibular excitation and inhibition of extraocular motoneurons underlying this reflex is reciprocally organized and allows coordinated activation of particular eye muscles and concurrent relaxation of their antagonistic counterparts. Here, we demonstrate in isolated preparations of Xenopus laevis tadpoles that the discharge modulation of superior oblique motoneurons during cyclic head motion derives from an alternating excitation and inhibition...
March 19, 2018: Journal of Neurology
Sandra G Gonzalez Malagon, Anna M Lopez Muñoz, Daniel Doro, Triòna G Bolger, Evon Poon, Elizabeth R Tucker, Hadeel Adel Al-Lami, Matthias Krause, Christopher J Phiel, Louis Chesler, Karen J Liu
Neural crest migration is critical to its physiological function. Mechanisms controlling mammalian neural crest migration are comparatively unknown, due to difficulties accessing this cell population in vivo. Here we report requirements of glycogen synthase kinase 3 (GSK3) in regulating the neural crest in Xenopus and mouse models. We demonstrate that GSK3 is tyrosine phosphorylated (pY) in mouse neural crest cells and that loss of GSK3 leads to increased pFAK and misregulation of Rac1 and lamellipodin, key regulators of cell migration...
March 19, 2018: Nature Communications
Runlai Hang, Zhen Wang, Xian Deng, Chun Yan Liu, Bin Yan, Chao Yang, Xianwei Song, Beixin Mo, XiaoFeng Cao
Ribosome biogenesis is crucial for plant growth and environmental acclimation. Processing of ribosomal RNAs (rRNAs) is an essential step in ribosome biogenesis and begins with transcription of the rDNA. The resulting pre-rRNA transcript undergoes systematic processing, where multiple endonucleolytic and exonucleolytic cleavages remove the external and internal transcribed spacers (ETS and ITS). The processing sites and pathways for pre-rRNA processing have been deciphered in Saccharomyces cerevisiae and, to some extent, in Xenopus, mammalian cells, and Arabidopsis thaliana...
March 19, 2018: Plant Physiology
Briony D Smith, Krystal J Vail, Gwendolyn L Carroll, Maggie C Taylor, Nicholas D Jeffery, Tracy H Vemulapalli, James J Elliott
Often few alternative anesthetics for exotic species are available, due to the small numbers of these animals used in research. In this study, we evaluated the depth and duration of anesthesia in Xenopus laevis after their immersion in 3 doses of etomidate (15, 22.5, and 30 mg/L) and in 3 doses of benzocaine (0.1%, 0.5%, and 1%) compared with the 'gold standard,' tricaine methanesulfonate (MS222; 2 g/L). We then chose an optimal dose for each alternative anesthetic according to induction time, duration of surgical plane, and time to complete recovery...
March 1, 2018: Journal of the American Association for Laboratory Animal Science: JAALAS
Gang Wang, Qian Wang, Zhengyan Li, Chaoxu Liu, Xianli He
Xenopus kinesin-like protein 2 (TPX2) is a microtubule-associated protein that plays an important role in spindle assembly and dynamics. However, the clinical and prognostic value of TPX2 in the digestive system cancers remains unclear. The objective of this review was to evaluate the association of TPX2 expression with disease-free survival (DFS), overall survival (OS), and clinicopathological features of digestive system cancers. The software Stata 12.0 was used to analyze the outcomes, including OS, disease-free survival (DFS), and clinicopathological characteristics...
2018: OncoTargets and Therapy
Hyeyoon Lee, Seong-Moon Cheong, Wonhee Han, Youngmu Koo, Saet-Byeol Jo, Gun-Sik Cho, Jae-Seong Yang, Sanguk Kim, Jin-Kwan Han
Dishevelled (Dvl/Dsh) is a key scaffold protein that propagates Wnt signaling essential for embryogenesis and homeostasis. However, whether antagonism of Wnt signaling necessary for vertebrate head formation can be achieved through regulation of Dsh protein stability is unclear. Here we show that membrane-associated RING-CH2 (March2), a RING-type E3 ubiquitin ligase, antagonizes Wnt signaling by regulating the turnover of Dsh protein via ubiquitin-mediated lysosomal degradation in prospective head region of Xenopus We further found that March2 acquires regional and functional specificities for head formation from the Dsh-interacting protein Dapper1 (Dpr1)...
March 16, 2018: Development
Andrew M Holmes, Christopher J Emmans, Robert Coleman, Tessa E Smith, Charlotte A Hosie
Understanding the immediate and longer-term effects of transportation and re-housing in a laboratory species is crucial in order to refine the transfer process, enable the optimal introduction of new animals to a novel environment and to provide a sufficient acclimatisation period before usage. Whilst consideration of animal welfare in most model vertebrate species has received attention, little quantitative evidence exists for the optimal care of the common laboratory amphibian Xenopus laevis. Techniques for the non-invasive welfare assessment of amphibians are also limited and here a non-invasive physiological assay was developed to investigate the impacts of transportation, transport medium and re-housing on X...
March 12, 2018: General and Comparative Endocrinology
Jiejing Li, Mark Perfetto, Russell Neuner, Harinath Bahudhanapati, Laura Christian, Ketan Mathavan, Lance C Bridges, Dominique Alfandari, Shuo Wei
During vertebrate gastrulation, canonical Wnt signaling induces the formation of neural plate border (NPB). Wnt is also thought to be required for the subsequent specification of neural crest (NC) lineage at the NPB, but the direct evidence is lacking. We found previously that the disintegrin metalloproteinase ADAM13 is required for Wnt activation and NC induction in Xenopus Here we report that knockdown of ADAM13 or its close paralog ADAM19 severely downregulates Wnt activity at the NPB, inhibiting NC specification without affecting earlier NPB formation...
March 14, 2018: Development
Ellen A G Chernoff, Kazuna Sato, Hai V N Salfity, Deborah A Sarria, Teri Belecky-Adams
The differentiated state of spinal cord ependymal cells in regeneration-competent amphibians varies between a constitutively active state in what is essentially a developing organism, the tadpole of the frog Xenopus laevis , and a quiescent, activatable state in a slowly growing adult salamander Ambystoma mexicanum , the Axolotl. Ependymal cells are epithelial in intact spinal cord of all vertebrates. After transection, body region ependymal epithelium in both Xenopus and the Axolotl disorganizes for regenerative outgrowth (gap replacement)...
2018: Frontiers in Cellular Neuroscience
David R Shook, Eric M Kasprowicz, Lance A Davidson, Raymond Keller
Indirect evidence suggests that blastopore closure during gastrulation of anamniotes, including amphibians such as Xenopus laevis , depends on circumblastoporal convergence forces generated by the marginal zone (MZ), but direct evidence is lacking. We show that explanted MZs generate tensile convergence forces up to 1.5 mN during gastrulation and over 4 mN thereafter. These forces are generated by convergent thickening (CT) until the midgastrula and increasingly by convergent extension (CE) thereafter. Explants from ventralized embryos, which lack tissues expressing CE but close their blastopores, produce up to 2 mN of tensile force, showing that CT alone generates forces sufficient to close the blastopore...
March 13, 2018: ELife
J Kabutomori, O Beloto-Silva, R R Geyer, R Musa-Aziz
Xenopus laevis oocytes are a valuable tool for investigating the function of membrane proteins. However, regulations around the world, specifically in Brazil, render the import of Xenopus laevis frogs impractical, and, in some cases, impossible. Here, as an alternative, we evaluate the usefulness of the North American aquatic bullfrog Lithobates catesebeianus , which is commercially available in Brazil, for the heterologous expression of aquaporin (AQP) proteins. We have developed a method that combines a brief collagenase treatment and mechanical defolliculation for isolating individual oocytes from Lithobates ovaries...
March 12, 2018: Biology Open
Bo Zhang, Uyen Tran, Oliver Wessely
The development of the kidney relies on the establishment and maintenance of a precise tubular diameter of its functional units, the nephrons. This process is disrupted in Polycystic Kidney Disease (PKD) resulting in dilations of the nephron and renal cyst formation. In the course of exploring G-protein coupled signaling in the Xenopus pronephric kidney we discovered that loss of the G-protein alpha subunit Gnas results in a PKD phenotype. Polycystin-1, one of the genes mutated in human PKD, encodes for a protein resembling a G-protein coupled receptor...
March 12, 2018: Development
Md Fazlur Rahman, Radhika Raj, Rajgopal Govindarajan
Combination antiretroviral drug treatments depend on 3'-deoxy-nucleoside analogs such as AZT (3'-azido-3'-deoxythymidine) and DDI (2'3'-dideoxyinosine). Despite being effective in inhibiting HIV viral replication, these drugs produce a range of toxicities, including myopathy, pancreatitis, neuropathy and lactic acidosis, that are generally considered as sequelae to mitochondrial damage. While the cell surface localized nucleoside transporters (e.g., human equilibrative nucleoside transporter 2 (hENT2), human concentrative nucleoside transporter 1 (hCNT1)) are known to increase the carrier mediated uptake of 3'-deoxy-nucleoside analogs into cells, another ubiquitously expressed intracellular nucleoside transporter, namely, hENT3, has been implicated in the mitochondrial transport of 3'-deoxy-nucleoside analogs...
March 12, 2018: Drug Metabolism and Disposition: the Biological Fate of Chemicals
Ye Jin, Daniel C Weinstein
The cement gland in Xenopus laevis has long been used as a model to study the interplay of cell signaling and transcription factors during embryogenesis. It has been shown that an intermediate level of Bone Morphogenetic Protein (BMP) signaling is essential for cement gland formation. In addition, several transcription factors have been linked to cement gland development. One of these, the homeodomain-containing protein Pitx1, can generate ectopic cement gland formation; however, the mechanisms underlying this process remain obscure...
March 9, 2018: Developmental Biology
Asimina Kerimi, Hilda Nyambe-Silavwe, Alison Pyner, Ebun Oladele, Julia S Gauer, Yala Stevens, Gary Williamson
PURPOSE: The secoiridoid oleuropein, as found in olives and olive leaves, modulates some biomarkers of diabetes risk in vivo. A possible mechanism may be to attenuate sugar digestion and absorption. METHODS: We explored the potential of oleuropein, prepared from olive leaves in a water soluble form (OLE), to inhibit digestive enzymes (α-amylase, maltase, sucrase), and lower [14 C(U)]-glucose uptake in Xenopus oocytes expressing human GLUT2 and [14 C(U)]-glucose transport across differentiated Caco-2 cell monolayers...
March 9, 2018: European Journal of Nutrition
Mansour Alkobtawi, Heather Ray, Elias H Barriga, Mauricio Moreno, Ryan Kerney, Anne-Helene Monsoro-Burq, Jean-Pierre Saint-Jeannet, Roberto Mayor
The neural crest is a multipotent population of cells that originates a variety of cell types. Many animal models are used to study neural crest induction, migration and differentiation, with amphibians and birds being the most widely used systems. A major technological advance to study neural crest development in mouse, chick and zebrafish has been the generation of transgenic animals in which neural crest specific enhancers/promoters drive the expression of either fluorescent proteins for use as lineage tracers, or modified genes for use in functional studies...
March 6, 2018: Developmental Biology
Jacques Robert
Although the amphibian Xenopus laevis produces antibodies as diversified as those from mammals in the primary repertoire, antibody affinity maturation after immunization is relatively poor and has been associated with a poor B cell selection of AID-mediated hypermutations and lack of germinal centers in the spleen, the only secondary lymphoid organ of this amphibian. In this issue of the European Journal of Immunology, Neely et al., [Eur. J. Immunol. 2018. 48: 430-440] have unveiled the role of distinctive dendritic cell (DC) subset, XL cells, which have the capacity to acquire and retain native antigens for B cell maturation...
March 2018: European Journal of Immunology
Alexander Perniss, Kathrin Preiss, Marcel Nier, Mike Althaus
A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.
March 8, 2018: Scientific Reports
Lih-Chu Chiou, Hsin-Jung Lee, Margot Ernst, Wei-Jan Huang, Jui-Feng Chou, Hon-Lie Chen, Akihiro Mouri, Liang-Chieh Chen, Marco Treven, Takayoshi Mamiya, Pi-Chuan Fan, Daniel E Knutson, Chris Witzigmann, James Cook, Werner Sieghart, Toshitaka Nabeshima
BACKGROUND AND PURPOSE: The pathophysiological role of α6 subunit-containing GABAA receptors (α6GABAA Rs), which are mainly expressed in cerebellar granule cells, remains unclear. Recently, we demonstrated that hispidulin, a flavonoid isolated from a local herb that remitted a patient's intractable motor tics, attenuated methamphetamine-induced hyperlocomotion in mice as a positive allosteric modulator (PAM) of cerebellar α6GABAA Rs. Here, using hispidulin and a selective α6GABAA R PAM, the pyrazoloquinolinone Compound 6, we revealed an unprecedented role of cerebellar α6GABAA Rs in disrupted prepulse inhibition (PPI), which reflects sensorimotor gating deficits manifested in several neuropsychiatric disorders...
March 8, 2018: British Journal of Pharmacology
Rafal P Piprek, Milena Damulewicz, Malgorzata Kloc, Jacek Z Kubiak
Development of the gonads is a complex process, which starts with a period of undifferentiated, bipotential gonads. During this period the expression of sex-determining genes is initiated. Sex determination is a process triggering differentiation of the gonads into the testis or ovary. Sex determination period is followed by sexual differentiation, i.e. appearance of the first testis- and ovary-specific features. In Xenopus laevis W-linked DM-domain gene (DM-W) had been described as a master determinant of the gonadal female sex...
March 2, 2018: Differentiation; Research in Biological Diversity
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