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Erick Arias, Brian Kubicki
A new salamander belonging to the genus Nototriton, subgenus Nototriton, is described from the Caribbean slopes of the southeastern Cordillera de Talamanca in Costa Rica, within Parque Internacional La Amistad, at an elevation ca. 1500 m a.s.l. This new taxon is distinguished from its congeners by its morphological characteristics and by its differentiation in DNA sequences of the 16S rRNA, cytochrome oxidase subunit I (COI), and cytochrome b mitochondrial genes. This new species represents the southernmost extension known for the genus Nototriton...
January 7, 2018: Zootaxa
Catherina G Becker, Thomas Becker, Jean-Philippe Hugnot
Spinal cord injury results in the loss of neurons and axonal connections. In mammals, including humans, this loss is permanent, but is repaired in other vertebrates, such as salamanders and fishes. Cells in the ependymal niche play a pivotal role for the outcome after injury. These cells initiate proliferation and generate new neurons of different types in regenerating species, but only glial cells, contributing to the glial scar, in mammals. Here we compare the cellular and molecular properties of ependymal zone cells and their environment across vertebrate classes...
April 9, 2018: Progress in Neurobiology
Steven Gardner, George Cline, Nixon Mwebi, James Rayburn
Arsenic (As) and chromium (Cr) are two contaminants that are detected in aquatic and terrestrial habitats. Using the spotted salamander, Ambystoma maculatum, to assess impacts from these contaminants may be advantageous as adults live and breed in such environments. Adult amphibians typically exhibit elevated tissue concentrations of contaminants present in their environment, while larval stages were found to exhibit increased sensitivity to pollutants. From January through March of 2015, during the spring breeding season, 5 adults and approximately 32 egg masses were collected from a local breeding site...
April 4, 2018: Journal of Toxicology and Environmental Health. Part A
Jian-Ping Jiang, Jia Jia, Meihua Zhang, Ke-Qin Gao
The Longdong Stream Salamander Batrachuperus londongensis , living in a mountain stream environment at Mt. Emei in Sichuan Province, China, represents a rare species that is facultatively neotenic in the family Hynobiidae. Although the species has been known to science for some 40 years since its initial discovery in the late 1970s, anatomical details of its osteology remain poorly understood and developmental information is still lacking for the species. This study (1) provides a detailed osteological account of B...
2018: PeerJ
Thierry Chambert, David S Pilliod, Caren S Goldberg, Hideyuki Doi, Teruhiko Takahara
Environmental DNA (eDNA) analysis of water samples is on the brink of becoming a standard monitoring method for aquatic species. This method has improved detection rates over conventional survey methods and thus has demonstrated effectiveness for estimation of site occupancy and species distribution. The frontier of eDNA applications, however, is to infer species density. Building upon previous studies, we present and assess a modeling approach that aims at inferring animal density from eDNA. The modeling combines eDNA and animal count data from a subset of sites to estimate species density (and associated uncertainties) at other sites where only eDNA data are available...
March 2018: Ecology and Evolution
Thomas J Hossie, Shawn MacFarlane, Amy Clement, Dennis L Murray
Intraspecific aggression represents a major source of mortality for many animals and is often experienced alongside the threat of predation. The presence of predators can strongly influence ecological systems both directly by consuming prey and indirectly by altering prey behavior or habitat use. As such, the threat of attack by higher level predators may strongly influence agonistic interactions among conspecifics via nonconsumptive (e.g., behaviorally mediated) predator effects. We sought to investigate these interactions experimentally using larval salamanders ( Ambystoma maculatum ) as prey and dragonfly nymphs ( Anax junius ) as predators...
March 2018: Ecology and Evolution
Shu Chen, Andrew A Cunningham, Gang Wei, Jian Yang, Zhiqiang Liang, Jie Wang, Minyao Wu, Fang Yan, Hanbin Xiao, Xavier A Harrison, Nathalie Pettorelli, Samuel T Turvey
The purpose of this study was to determine whether limited occurrence data for highly threatened species can provide useful spatial information to inform conservation. The study was conducted across central and southern China. We developed a habitat suitability model for the Critically Endangered Chinese giant salamander ( Andrias davidianus ) based on one biotic and three abiotic parameters from single-site locality records, which represent the only relevant environmental data available for this species. We then validated model quality by testing whether increased percentage of predicted suitable habitat at the county level correlated with independent data on giant salamander presence...
March 2018: Ecology and Evolution
Constanze Bickelmann, Gabriela Neiva Frota-Lima, Sandra Karla Triepel, Akane Kawaguchi, Igor Schneider, Nadia Belinda Fröbisch
Limb development in salamanders is unique among tetrapods in significant ways. Not only can salamanders regenerate lost limbs repeatedly and throughout their lives, but also the preaxial zeugopodial element and digits form before the postaxial ones and, hence, with a reversed polarity compared to all other tetrapods. Moreover, in salamanders with free-swimming larval stages, as exemplified by the axolotl (Ambystoma mexicanum), each digit buds independently, instead of undergoing a paddle stage. Here, we report gene expression patterns of Hoxa and d clusters, and other crucial transcription factors during axolotl limb development...
March 30, 2018: Journal of Experimental Zoology. Part B, Molecular and Developmental Evolution
Alicia K Bird, Sofia R Prado-Irwin, Vance T Vredenburg, Andrew G Zink
A multitude of microorganisms live on and within plant and animal hosts, yet the ecology and evolution of these microbial communities remains poorly understood in many taxa. This study examined the extent to which environmental factors and host taxonomic identity explain microbiome variation within two salamander genera, Ensatina and Batrachoseps , in the family Plethodontidae. In particular, we assessed whether microbiome differentiation paralleled host genetic distance at three levels of taxonomy: genus and high and low clade levels within Ensatina eschscholtzii ...
2018: Frontiers in Microbiology
Walter Jetz, R Alexander Pyron
Human activities continue to erode the tree of life, requiring us to prioritize research and conservation. Amphibians represent key victims and bellwethers of global change, and the need for action to conserve them is drastically outpacing knowledge. We provide a phylogeny incorporating nearly all extant amphibians (7,238 species). Current amphibian diversity is composed of both older, depauperate lineages and extensive, more recent tropical radiations found in select clades. Frog and salamander diversification increased strongly after the Cretaceous-Palaeogene boundary, preceded by a potential mass-extinction event in salamanders...
March 26, 2018: Nature Ecology & Evolution
Jim Kling
No abstract text is available yet for this article.
March 26, 2018: Lab Animal
Tara A Pelletier, Robert D Denton
Reproductive isolation is the result of either the inability to produce viable and fertile offspring or the avoidance of mating altogether. While these mechanisms can evolve either over time via genetic drift or natural selection, the genetic result is usually a complex set of traits that are often linked. Explaining how reproductive isolation proceeds from the initiation of divergence to the complete prevention of mating is often a difficult task, as the underlying genes for traits associated with reproductive isolation can change via molecular evolution and subsequent protein coding alterations or through alterations of gene expression regulation...
January 2018: Molecular Ecology
Fei Ke, Jian-Fang Gui, Zhong-Yuan Chen, Tao Li, Cun-Ke Lei, Zi-Hao Wang, Qi-Ya Zhang
BACKGROUND: Ranaviruses (family Iridoviridae, nucleocytoplasmic large DNA viruses) have been reported as promiscuous pathogens of cold-blooded vertebrates. Rana grylio virus (RGV, a ranavirus), from diseased frog Rana grylio with a genome of 105.79 kb and Andrias davidianus ranavirus (ADRV), from diseased Chinese giant salamander (CGS) with a genome of 106.73 kb, contains 99% homologous genes. RESULTS: To uncover the differences in virus replication and host responses under interspecies infection, we analyzed transcriptomes of CGS challenged with RGV and ADRV in different time points (1d, 7d) for the first time...
March 20, 2018: BMC Genomics
Xiangyi Wen, Matthew J Van Hook, Justin J Grassmeyer, Alex I Wiesman, Grace M Rich, Karlene M Cork, Wallace B Thoreson
Endocytosis is an essential process at sites of synaptic release. Not only are synaptic vesicles recycled by endocytosis, but the removal of proteins and lipids by endocytosis is needed to restore release site function at active zones after vesicle fusion. Synaptic exocytosis from vertebrate photoreceptors involves synaptic ribbons that serve to cluster vesicles near the presynaptic membrane. In this study, we hypothesize that this clustering increases the likelihood that exocytosis at one ribbon release site may disrupt release at an adjacent site and therefore that endocytosis may be particularly important for restoring release site competence at photoreceptor ribbon synapses...
March 19, 2018: Journal of General Physiology
Robert W Bryson, Eugenia Zarza, Jared A Grummer, Gabriela Parra-Olea, Oscar Flores-Villela, John Klicka, John E McCormack
Mountain formation in Mexico has played an important role in the diversification of many Mexican taxa. The Trans-Mexican Volcanic Belt in particular has served as both a cradle of diversification and conduit for dispersal. We investigated the evolutionary history of the Isthmura bellii group of salamanders, a widespread amphibian across the Mexican highlands, using sequence capture of ultraconserved elements. Results suggest that the I. bellii group probably originated in southeastern Mexico in the late Miocene and later dispersed across the Trans-Mexican Volcanic Belt and into the Sierra Madre Occidental...
March 16, 2018: Molecular Phylogenetics and Evolution
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
Ryan R Kerney, James Hanken, David C Blackburn
Direct-developing amphibians form limbs during early embryonic stages, as opposed to the later, often postembryonic limb formation of metamorphosing species. Limb patterning is dramatically altered in direct-developing frogs, but little attention has been given to direct-developing salamanders. We use expression patterns of two genes, sox9 and col2a1, to assess skeletal patterning during embryonic limb development in the direct-developing salamander Plethodon cinereus. Limb patterning in P. cinereus partially resembles that described in other urodele species, with early formation of digit II and a generally anterior-to-posterior formation of preaxial digits...
March 12, 2018: Evolution & Development
Ellen Heber-Katz, Phillip Messersmith
The capacity to regenerate entire body parts, tissues, and organs had generally been thought to be lost in evolution with very few exceptions (eg. the liver) surviving in mammals. The discovery of the MRL mouse and the elucidation of the underlying molecular pathway centering around hypoxia inducible factor, HIF-1α, has allowed a drug and materials approach to regeneration in mice and hopefully humans. The HIF-1α pathway is ancient and permitted the transition from unicellular to multicellular organisms. Furthermore, HIF-1α and its regulation by PHDs, important oxygen sensors in the cell, provides a perfect drug target...
March 7, 2018: Advanced Drug Delivery Reviews
Ruth Morona, Jesús M López, R Glenn Northcutt, Agustín González
Lungfishes are the closest living relatives of land vertebrates, and their neuroanatomical organization is particularly relevant for deducing the neural traits that have been conserved, modified, or lost with the transition from fishes to land vertebrates. The immunohistochemical localization of calbindin (CB) and calretinin (CR) provides a powerful method for discerning segregated neuronal populations, fiber tracts, and neuropils and is here applied to the brains of Neoceratodus and Protopterus, representing the two extant orders of lungfishes...
March 9, 2018: Journal of Comparative Neurology
Eugenia Sanchez, Eliane Küpfer, Daniel J Goedbloed, Arne W Nolte, Tim Lüddecke, Stefan Schulz, Miguel Vences, Sebastian Steinfartz
The postembryonic development of amphibians has been characterized as divided into three predominant periods, hereafter named primary developmental stages: premetamorphosis (PreM), prometamorphosis (ProM), metamorphic climax (Meta), and completion of metamorphosis (PostM), largely based on examination of anuran development. Here, we categorized the postembryonic development of larvae of a poisonous fire salamander (Salamandra salamandra) by integrating morphology and gene expression (transcriptomic) data. Morphological analysis revealed three distinct clusters suggestive of PreM, ProM, and Meta, which were confirmed in parallel by microarray-derived gene expression analysis...
March 5, 2018: Journal of Experimental Zoology. Part B, Molecular and Developmental Evolution
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