The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform

Haas Alexander - One of the best experts on this subject based on the ideXlab platform.

Bruce Waldman - One of the best experts on this subject based on the ideXlab platform.

  • Skin bacterial community reorganization following metamorphosis of the fire-bellied toad (Bombina orientalis)
    Microbial Ecology, 2018
    Co-Authors: Arnaud Bataille, Larisa Lee-cruz, Binu Tripathi, Bruce Waldman
    Abstract:

    In organisms with complex life histories, dramatic changes in microbial community structure may occur with host development and immune system maturation. Amphibian host susceptibility to diseases such as chytridiomycosis may be affected by the reorganization of skin microbial community structure that occurs during metamorphosis. We tracked changes in the bacterial communities inhabiting skin of Korean fire-bellied toads (Bombina orientalis) that we infected as tadpoles with different strains of Batrachochytrium dendrobatidis (Bd), the pathogenic fungus that causes chytridiomycosis. We found that B. orientalis undergoes a major change in skin bacterial community composition between 5 and 15 days following metamorphosis. Richness indices and phylogenetic diversity measures began to diverge earlier, between aquatic and terrestrial stages. Our results further reveal differences in skin bacterial community composition among infection groups, suggesting that the effect of Bd infection on skin microbiome composition may differ by Bd strain. Additional studies are needed to further investigate the structural and temporal dynamics of microbiome shifts during metamorphosis in wild and captive amphibian populations. Analyses of the ontogeny of microbiome shifts may contribute to an understanding of why amphibians vary in their susceptibility to chytridiomycosis.

  • Influence of geology and human activity on the genetic structure and demography of the Oriental fire-bellied toad (Bombina orientalis)
    Molecular phylogenetics and evolution, 2015
    Co-Authors: Jonathan J. Fong, Bao Tian Yang, Zheng Yan Zhou, Adam D. Leaché, Mi-sook Min, Bruce Waldman
    Abstract:

    Abstract The Oriental fire-bellied toad (Bombina orientalis) is a commonly used study organism, but knowledge of its evolutionary history is incomplete. We analyze sequence data from four genetic markers (mtDNA genes encoding cytochrome c oxidase subunit I, cytochrome b, and 12S–16S rRNA; nuDNA gene encoding recombination activating gene 2) from 188 individuals across its range in Northeast Asia to elucidate phylogeographic patterns and to identify the historic events that shaped its evolutionary history. Although morphologically similar across its range, B. orientalis exhibits phylogeographic structure, which we infer was shaped by geologic, climatic, and anthropogenic events. Phylogenetic and divergence-dating analyses recover four genetically distinct groups of B. orientalis: Lineage 1—Shandong Province and Beijing (China); Lineage 2—Bukhan Mountain (Korea); Lineage 3—Russia, Northeast China, and northern South Korea; and Lineage 4—South Korea. Lineage 2 was previously unknown. Additionally, we discover an area of secondary contact on the Korean Peninsula, and infer a single dispersal event as the origin of the insular Jeju population. Skyline plots estimate different population histories for the four lineages: Lineages 1 and 2 experienced population decreases, Lineage 3 remained stable, while Lineage 4 experienced a sharp increase during the Holocene. The timing of the population expansion of Lineage 4 coincides with the advent of rice cultivation, which may have facilitated the increase in population size by providing additional breeding habitat.

Engelkes Karolin - One of the best experts on this subject based on the ideXlab platform.

Tianbao Chen - One of the best experts on this subject based on the ideXlab platform.

  • the synergistic antimicrobial effects of novel bombinin and bombinin h peptides from the skin secretion of Bombina orientalis
    Bioscience Reports, 2017
    Co-Authors: Jie Xiang, Mei Zhou, Tianbao Chen, C. Shaw, Lei Wang
    Abstract:

    Bombinin and bombinin H are two antimicrobial peptide (AMP) families initially discovered from the skin secretion of Bombina that share the same biosynthetic precursor-encoding cDNAs, but have different structures and physicochemical properties. Insight into their possible existing relationship lead us to perform the combination investigations into their anti-infectious activities. In this work, we report the molecular cloning and functional characterisation of two novel AMPs belonging to bombinin and bombinin H families from secretions of Bombina orientalis . Their mature peptides (BHL-bombinin and bombinin HL), coded by single open-reading frame (ORF), were chemically synthesised along with an analogue peptide that replaced L-leucine with D-leucine from the 2nd position of the N-terminus (bombinin HD). Circular dichroism analysis revealed that all of them displayed well-defined α-helical structures in membrane mimicking environments. Furthermore, BHL-bombinin displayed broad-spectrum bactericidal activities on a wide range of micro-organisms, while bombinin H only exhibited a mildly bacteriostatic effect on the Gram-positive bacteria Staphylococcus aureus . The combination potency of BHL-bombinin with either bombinin HL or bombinin HD showed the synergistic inhibition activities against S. aureus (FICI 0.375). A synergistic effect has also been observed between bombinin H and ampicillin, which was further systematically evaluated and confirmed by in vitro time-killing investigations. Haemolytic and cytotoxic examinations exhibited a highly synergistic selectivity and low cytotoxicity on mammalian cells of these three peptides. Taken together, the discovery of the potent synergistic effect of AMPs in a single biosynthetic precursor with superior functional selectivity provides a promising strategy to combat multidrug-resistant pathogens in clinical therapy.

  • Peptide DV-28 amide: An inhibitor of bradykinin-induced arterial smooth muscle relaxation encoded by Bombina orientalis skin kininogen-2.
    Peptides, 2010
    Co-Authors: Lei Wang, Mei Zhou, Tianbao Chen, Yong Chen, Mu Yang, Da-yuan Sui, Christopher Shaw
    Abstract:

    Abstract Skin kininogens from bombinid toads encode an array of bradykinin-related peptides and one such kininogen from Bombina maxima also encodes the potent bradykinin B2-receptor antagonist, kinestatin. In order to determine if the skin secretion of the closely-related toad, Bombina orientalis , contained a bradykinin inhibitory peptide related to kinestatin, we screened reverse phase HPLC fractions of defensive skin secretion using a rat tail artery smooth muscle preparation. A fraction was located that inhibited bradykinin-induced relaxation of the preparation and this contained a peptide of 3198.5 Da as determined by MALDI-TOF MS. Automated Edman degradation of this peptide established the identity of a 28-mer as: DMYEIKGFKSAHGRPRVCPPGEQCPIWV, with a disulfide-bridge between Cys 18 and Cys 24 and an amidated C-terminal Val residue. Peptide DV-28 was found to correspond to residues 133–160 of skin pre-kininogen-2 of B. orientalis that also encodes two copies of (Thr 6 )-bradykinin. The C-terminal residue, Gly-161, of the precursor open-reading frame, acts as the C-terminal amide donor of mature DV-28. DV-28 amide thus represents a new class of bradykinin inhibitor peptide from amphibian skin secretion.

  • molecular cloning of mrna from toad granular gland secretion and lyophilized skin identification of bo8 a novel prokineticin from Bombina orientalis
    Peptides, 2005
    Co-Authors: Tianbao Chen, Mei Zhou, C. Shaw
    Abstract:

    Abstract Prokineticins are small (∼8 kDa), biologically active secretory proteins whose primary structures have been highly conserved throughout the Animal Kingdom. Representatives have been identified in the defensive skin secretions of several amphibians reflecting the immense structural/functional diversity of polypeptides in such. Here we describe the identification of a prokineticin homolog (designated Bo8) from the skin secretion of the Oriental fire-bellied toad ( Bombina orientalis ). Full primary structural characterization was achieved using a combination of direct Edman microsequencing, mass spectrometry and cloning of encoding skin cDNA. The latter approach employed a recently described technique that we developed for the cloning of secretory peptide cDNAs from lyophilized skin secretion, and this was further extended to employ lyophilized skin as the starting material for cDNA library construction. The Bo8 precursor was found to consist of an open-reading frame of 96 amino acid residues consisting of a putative 19-residue signal peptide followed by a single 77-residue prokineticin ( M r  = 7990 Da). Amino acid substitutions in skin prokineticins from the skin secretions of bombinid toads are confined to discrete sites affording the necessary information for structure/activity studies and analog design.

  • Identification and molecular cloning of novel trypsin inhibitor analogs from the dermal venom of the Oriental fire-bellied toad (Bombina orientalis) and the European yellow-bellied toad (Bombina variegata).
    Peptides, 2003
    Co-Authors: Tianbao Chen, Christopher Shaw
    Abstract:

    The structural diversity of polypeptides in amphibian skin secretion probably reflects different roles in dermal regulation or in defense against predators. Here we report the structures of two novel trypsin inhibitor analogs, BOTI and BVTI, from the dermal venom of the toads, Bombina orientalis and Bombina variegata. Cloning of their respective precursors was achieved from lyophilized venom cDNA libraries for the first time. Amino acid alignment revealed that both deduced peptides, consisting of 60 amino acid residues, including 10 cysteines and the reactive center motif, -CDKKC-, can be affirmed as structural homologs of the trypsin inhibitor from Bombina Bombina skin.

  • Bradykinins and their precursor Cdnas from the skin of the Fire-Bellied Toad (Bombina orientalis)
    Peptides, 2002
    Co-Authors: Tianbao Chen, David F. Orr, Anthony J. Bjourson, Stephen Mcclean, Martin O'rourke, David G. Hirst, Pingfan Rao, Christopher Shaw
    Abstract:

    Abstract Bradykinin and (Thr 6 )-bradykinin have been identified in the defensive skin secretion of the fire-bellied toad, Bombina orientalis . The homologous cDNAs for both peptides were cloned from a skin library using a 3′- and 5′-RACE strategy. Kininogen-1 (BOK-1) contained an open-reading frame of 167 amino acid residues encoding four repeats of bradykinin, and kininogen-2 (BOK-2) contained an open-reading frame of 161 amino acid residues encoding two repeats of (Thr 6 )-bradykinin. Alignment of both precursor nucleotide and amino acid sequences revealed a high degree of structural similarity. These amphibian skin kininogens/preprobradykinins are not biologically analogous to mammalian kininogens.

Myung Chan Gye - One of the best experts on this subject based on the ideXlab platform.

  • Nickel affects gill and muscle development in oriental fire-bellied toad (Bombina orientalis) embryos
    Aquatic toxicology (Amsterdam Netherlands), 2016
    Co-Authors: Chan-jin Park, Sang Ha Song, Dae Han Kim, Myung Chan Gye
    Abstract:

    Abstract The developmental toxicity of nickel was examined in the embryos of Bombina orientalis, a common amphibian in Korea. Based on a standard frog embryo teratogenesis assay, the LC50 and EC50 for malformation of nickel after 168 h of treatment were 33.8 μM and 5.4 μM, respectively. At a lethal concentration (100 μM), nickel treatment decreased the space between gill filaments and caused epithelial swelling and abnormal fusion of gill filaments. These findings suggest that nickel affects the functional development of gills, leading to embryonic death. At sublethal concentrations (1–10 μM), nickel produced multiple embryonic abnormalities, including bent tail and tail dysplasia. At 10 μM, nickel significantly decreased tail length and tail muscle fiber density in tadpoles, indicating inhibition of myogenic differentiation. Before hatching, the pre-muscular response to muscular response stages (stages 26–31) were the most sensitive period to nickel with respect to tail muscle development. During these stages, MyoD mRNA was upregulated, whereas myogenic regulatory factor 4 mRNA was downregulated by 0.1 μM nickel. Calcium-dependent kinase activities in muscular response stage embryos were significantly decreased by nickel, whereas these activities were restored by exogenous calcium. In tadpoles, 10 μM nickel significantly decreased the expression of the myosin heavy chain and the 12/101 muscle marker protein in the tail. Expression was restored by exogenous calcium. Our results indicate that nickel affects muscle development by disrupting calcium-dependent myogenesis in developing B. orientalis embryos.

  • Developmental and acute toxicity of cetylpyridinium chloride in Bombina orientalis (Amphibia: Anura).
    Aquatic toxicology (Amsterdam Netherlands), 2016
    Co-Authors: Chan-jin Park, Sang Ha Song, Dae Han Kim, Myung Chan Gye
    Abstract:

    Abstract In an effort to evaluate the toxicity of cetylpyridinium chloride (CPC), a cationic surfactant in amphibians, we examined the developmental and acute toxicity of CPC in Bombina orientalis embryos and tadpoles. Embryonic exposure to 2.0 μM (0.72 mg/l) CPC for 7 days significantly decreased the survival rates and increased DNA damage in the intestine of developed tadpoles. Exposure to 1.5 μM (0.54 mg/l) CPC significantly decreased the growth of embryos and increased developmental abnormalities. The 168-h LC50 and EC50 values of CPC were 1.95 μM (0.697 mg/l) and 1.48 μM (0.531 mg/l) in embryos, respectively. In an extended acute toxicity test using tadpoles, the 168-h LC50 value of CPC was 5.07 μM (1.82 mg/l). In terms of survival and growth rates, the lowest observed effective concentration of CPC was 1.5 μM. At sub-lethal concentrations (1.0 and 2.0 μM) CPC treatment to embryos increased lipid peroxidation in the intestine and gills of developed tadpoles, indicating that CPC can impose oxidative stress. At 2.0 μM CPC, pro-apoptotic Bax and Bak mRNA levels were significantly increased together with DNA fragmentation, indicative of apoptotic cell death. CPC in freshwater system may threaten the normal development of amphibian embryos.

  • effects of concrete materials for the stream restoration on Bombina orientalis embryos
    Ecology and resilient infrastructure, 2015
    Co-Authors: Chan-jin Park, Myung Chan Gye, Hong Kyu Ahn, Tae Hyeong Lee
    Abstract:

    Various adverse effects can occur due to direct exposure from toxic substances when toxic materials are used to restore river ecosystems. Thus, this study performed analysis on the development of toxicity in terms of survival and abnormality rates using embryos of Bombina orientalis living in Korea to analyze the toxicity of materials used in the river projects. The results showed that the toxicity in cement (C group) was the strongest whereas the toxicity in plant-based polyurethane (P1 group) was the weakest. Survival rates of B. orientalis embryos were 100%, 94 - 95%, 66 - 89% and 0% in control, P1, polyurethane (P2) and C groups, respectively. Abnormalities of embryos were 10.5%, 5.3 - 10.5%, 26.3 - 27.8% and 35.7% in control, P1, P2 and C groups, respectively. Furthermore, we verified that having a sufficient curing time reduced toxic substances that were extracted. The above result suggest that cement and polyurethane hamper the early development of amphibians. In conclusion, it is highly important to review biological safety with respect to the selection of materials used to restore rivers. This study shows the importance of the selection of eco-friendly materials and processes.

  • Developmental toxicity of treated municipal wastewater effluent on Bombina orientalis (Amphibia: Anura) embryos.
    Environmental toxicology and chemistry, 2014
    Co-Authors: Chan-jin Park, Hong Kyu Ahn, Hyo Min Ahn, Seong Chan Cho, Tae-hoon Kim, Seung-hoon Chun, Myung Chan Gye
    Abstract:

    Amphibian populations have been decreasing in urban freshwater systems in Korea. To elucidate the biological safety of treated wastewater effluent (TWE) in the Tancheon basin, the capital area of Korea, a 7-d–exposure Bombina orientalis embryo developmental toxicity assay was examined during the breeding season. In March, there were no significant differences in embryonic survival or malformation among the water samples. In July, following monsoon precipitation, embryonic lethality in TWE was significantly higher than in the upstream water sample. Malformation in TWE and TWE-mixed waters was significantly higher than in the control and upstream water samples. Tail muscle height of tadpoles also significantly decreased in TWE and TWE-mixed waters. Heavy metals were not detected in any samples. Total nitrogen, total phosphorous, and chemical oxygen demand in TWE markedly increased together with a decrease in dissolved oxygen in July. The increase in organic and inorganic loading following precipitation could have made TWE and TWE-mixed water not suitable for embryonic development. Though being managed based on physicochemical criteria, the water quality of TWE may not be sufficient to assure normal development of amphibian embryos. An amphibian developmental toxicity assay would be helpful for the water-quality management of TWE and urban freshwater systems in Korea. Environ Toxicol Chem 2014;33:954–961. © 2014 SETAC

  • effects of nonylphenol on early embryonic development pigmentation and 3 5 3 triiodothyronine induced metamorphosis in Bombina orientalis amphibia anura
    Chemosphere, 2010
    Co-Authors: Chan-jin Park, Han Seung Kang, Myung Chan Gye
    Abstract:

    Nonylphenol (NP) is an estrogenic endocrine disruptor in many aquatic species. In an effort to highlight the developmental toxicity of NP in amphibians, we examined the effects of NP on the embryonic survival, tadpole growth, melanophore development and metamorphosis of a native Korean amphibian species, Bombina orientalis (Anura). When treated to fertilized eggs, 1 μM NP significantly decreased embryonic survival at 48 h post fertilization (p.f.), suggesting that 1 μM NP can exert systemic toxicity in B. orientalis embryos. In the surviving embryos, there were no significant differences in malformation rates between NP-treated embryos and controls at 240 h p.f., suggesting no or low teratogenicity of NP in B. orientalis embryos. Below LC(50) NP significantly decreased body growth and development of melanophores at 0.1 μM, suggesting that NP far below the LC(50) targets multiple developmental events in tadpoles of this frog species. In metamorphosis assay using the premetamorphic tadpoles (corresponding to Nieuwkoop Faber stage 53 in Xenopus laevis) exogenous 3,5,3'-triiodothyronine (T3)-induced tail resorption was significantly decreased by 1 μM NP. However, NP (0.1 and 1 μM)-only treatment did not affected total body T3 and T4 levels, suggesting that NP at tested concentrations inhibits thyroid hormones action but not the synthesis of hormones during metamorphosis.