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Innes C. Cuthill - One of the best experts on this subject based on the ideXlab platform.

  • Distance-dependent defensive coloration in the poison frog Dendrobates tinctorius, Dendrobatidae
    2018
    Co-Authors: James B. Barnett, Constantine Michalis, Nicholas E. Scott-samuel, Innes C. Cuthill
    Abstract:

    Poison dart frogs provide classic examples of warning signals: potent toxins signaled by distinctive, conspicuous coloration. We show that, counterintuitively, the bright yellow and blue-black color of Dendrobates tinctorius (Dendrobatidae) also provides camouflage. Through computational modeling of predator vision, and a screen-based detection experiment presenting frogs at different spatial resolutions, we demonstrate that at close range the frog is highly detectable, but from a distance the colors blend together, forming effective camouflage. This result was corroborated with an in situ experiment, which found survival to be background-dependent, a feature more associated with camouflage than aposematism. Our results suggest that in D. tinctorius the distribution of pattern elements, and the particular colors expressed, act as a highly salient close range aposematic signal, while simultaneously minimizing detectability to distant observers.

  • image_data
    2018
    Co-Authors: James B. Barnett, Constantine Michalis, Nicholas E. Scott-samuel, Innes C. Cuthill
    Abstract:

    Image data associated with Barnett, J.B. et al. "Distance dependent defensive coloration in the poison frog Dendrobates tinctorius, Dendrobatidae

  • survival_data
    2018
    Co-Authors: James B. Barnett, Constantine Michalis, Nicholas E. Scott-samuel, Innes C. Cuthill
    Abstract:

    Survival data associated with Barnett, J.B. et al. "Distance dependent defensive coloration in the poison frog Dendrobates tinctorius, Dendrobatidae

John W Daly - One of the best experts on this subject based on the ideXlab platform.

  • Dendrobates pumilio, and Comments on Taxonomic Use of Skin Alkaloids
    2016
    Co-Authors: Charles W. Myers, Martin H Garraffo, John W Daly, Anthony. Wisnieski
    Abstract:

    Dendrobates granuliferus, previously thought to be a characteristic endemic ofPacific-side rain for-est in the Golfo Dulce region, was found in sym-patry with Dendrobates pumilio on the Caribbean coast of southeastern Costa Rica, near the Pana-manian border. The sympatric frogs were easily separated by features of coloration and skin tex-ture. Relative abundance in microsympatry was about 100 pumilio:4 granuliferus. Inasmuch as Dendrobates pumilio is sometimes strikingly polymorphic within populations, the initial identifications were tested with bioacoust-ical, skin-alkaloid, and allozyme data. These com-parisons negate the possibility of intrapopulation

  • a siphonotid millipede rhinotus as the source of spiropyrrolizidine oximes of dendrobatid frogs
    2003
    Co-Authors: Ralph A. Saporito, Maureen A Donnelly, R L Hoffman, H M Garraffo, John W Daly
    Abstract:

    Poison frogs of the neotropical family Dendrobatidae contain a wide variety of lipophilic alkaloids, which are accumulated from alkaloid-containing arthropods. A small millipede, Rhinotus purpureus (Siphonotidae), occurs microsympatrically with the dendrobatid frog Dendrobates pumilio on Isla Bastimentos, Bocas del Toro Province, Panama. Methanol extracts of this millipede contain the spiropyrrolizidine O-methyloxime 236, an alkaloid previously known only from skin extracts of poison frogs, including populations of D. pumilio. Thus, R. purpureus represents a likely dietary source of such alkaloids in dendrobatid frogs.

  • Evidence for an enantioselective pumiliotoxin 7-hydroxylase in dendrobatid poison frogs of the genus Dendrobates
    2003
    Co-Authors: John W Daly, H. Martin Garraffo, Valerie C. Clark, Herman Ziffer, John F. Cover
    Abstract:

    Dendrobatid poison frogs readily accumulate alkaloids from diet into skin, where such compounds serve as a chemical defense against predators. Arthropods seem to be the source of decahydroquinolines (DHQs), several izidines, coccinellines, spiropyrrolizidines, pumiliotoxins (PTXs), and allopumiliotoxins (aPTXs). A DHQ iso-223F, and PTX (+)-251D were fed to poison frogs of the dendrobatid genera Dendrobates, Epipedobates, and Phyllobates. The two alkaloids were accumulated in skin unchanged except for the three species of Dendrobates, where ≈80% of accumulated PTX (+)-251D was stereoselectively hydroxylated to aPTX (+)-267A. The unnatural enantiomer PTX (-)-251D was accumulated efficiently when fed to Dendrobates auratus, but was not hydroxylated. The enantiomers of PTX 251D and their desmethyl analogs were synthesized from N-Boc-protected (-)- and (+)-proline methyl esters. Both PTX (+)-251D and aPTX (+)-267A proved to be potent convulsants in mice, with (+)-267A being ≈5-fold more toxic than (+)-251D. Both alkaloids were hyperalgesic at the site of injection. The unnatural PTX (-)-251D caused no overt effect in mice. Thus, the evolutionary development of a pumiliotoxin 7-hydroxylase would have provided frogs of the genus Dendrobates with a means of enhancing the antipredator potency of ingested PTXs.

  • structure of alkaloid 275a a novel 1 azabicyclo 5 3 0 decane from a dendrobatid frog Dendrobates lehmanni synthesis of the tetrahydrodiastereomers
    2001
    Co-Authors: H M Garraffo, Thomas F Spande, John W Daly, P Jain, Tappey H Jones, L J Smith, V E Zottig
    Abstract:

    The principal alkaloid 275A in skins of the Colombian poison frog Dendrobates lehmanni has been identified as the pyrrolo[1,2-a]azepane (1), the first occurrence in nature of this "izidine" system. Tetrahydro-1 proved identical to one of the four synthetic diastereomers, 2a--2d, thereby establishing that 1 has the 5Z,10E relative stereochemistry. Alkaloid 1 is often accompanied by other congeners, in particular a 5Z,10Z diastereomer 15, a dihydro analogue 16, and a ketone 17. Such izidines in frogs may arise from dietary ants, as do other classes of izidines.

  • alkaloids from frog skin the discovery of epibatidine and the potential for developing novel non opioid analgesics
    2000
    Co-Authors: John W Daly, Martin H Garraffo, Michael W Decker, James P Sullivan, Michael Williams
    Abstract:

    Research on the nature, structure and biological activity of the toxins present in the skin of poison-dart frogs of South America began in the Laboratory of Chemistry at the National Institutes of Health in the mid-1960s. The presence of toxins in the skin of such frogs had been discovered long ago by Indians of Western Colombia, who to this day use skin secretions from three Colombian species of dendrobatid frogs (genus Phyllobates) to poison the grooved tips of blow darts used in hunting small game and birds. Initial field work on a poison-dart frog of the Rio San Juan drainage, and preparation of extracts was first conducted by F. Marki in 1962 and then by Daly in 1964 and 1966. The toxic principles were isolated and proved on structural analysis to be steroidal alkaloids, which were named batrachotoxins.1 These were then shown to be specific and potent activators of sodium channels.2 Both the natural alkaloids and a radioactive analog have proven to be invaluable research tools for the study of sodium channels and their interaction with local anesthetics, anticonvulsants, antiarrythmics and other drugs.3 The structure of batrachotoxin and other alkaloids, subsequently isolated from frog skin, are shown in Fig. 1. These initial studies on the batrachotoxin alkaloids from the poison-dart frogs of Western Colombia might never have been extended to some sixty species of poison-frogs of the neotropical family Dendrobatidae, had not Charles W. Myers, a herpetologist working on the reptiles and amphibians of Panama, contacted Daly and proposed a collaboration on the toxicity of an extremely variable dendrobatid frog (genus Dendrobates) of the Bocas Archipelago of Panama. The initial hypothesis, namely that the more brightly colored populations would contain higher levels of toxic alkaloids, proved incorrect. However, the analyses revealed not the steroidal batrachotoxins, but instead a variety of simpler bicyclic alkaloids, including the relatively toxic pumiliotoxins and relatively nontoxic decahydroquinolines.4 The pumiliotoxins and related alkaloids later were shown to be potent myotonic/cardiotonic agents5 with modulatory effects on sodium channels.6 The initial field work by Myers and Daly led to a thirty year friendship and collaboration with the aim of analyzing the distribution, nature, structure and biological activity of alkaloids in frog skin. A major field trip by Myers and Daly in the early 1970s led to the isolation and structural determination of relatively nontoxic bicyclic histrionicotoxins,7 later established as highaffinity noncompetitive blockers of nicotinic acetylcholine receptor-channels (nAChRs).3 Over the next three decades more than 500 alkaloids of at least two dozen structural classes were discovered, most of which have, as yet, not been found elsewhere in nature.8,9 This is remarkable, since the dendrobatid frogs apparently do not synthesize any of their skin alkaloids, but instead sequester them unchanged into skin glands from dietary sources10 to be used as secreted chemical deterrents to predators. The search over the past five years for the dietary sources of the batrachotoxins, pumiliotoxins and histrionicotoxins has been frustrating, but some six classes of relatively simple decahydroquinolines, piperidines, pyrrolidines and “izidines” of dendrobatid frog skin have been found in ants, while certain of the tricyclic and spiropyrrolizidine alkaloids occur in beetles and millipedes, respectively.10,11 Fig. 1 Structures of epibatidine and other alkaloids discovered in skin extracts from poison frogs (family Dendrobatidae). Batrachotoxin from Colombian Phyllobates aurotaenia,1 pumiliotoxin B from Panamanian Dendrobates pumilio,4 histrionicotoxin from Colombian Dendrobates histrionicus,7 and epibatidine and alkaloids 251D, 251H and 341A from Ecuadorian Epipedobates tricolor.12–14,16 EMINENT SCIENTIST REVIEW

Vigo Rodríguez, Martha J. - One of the best experts on this subject based on the ideXlab platform.

James B. Barnett - One of the best experts on this subject based on the ideXlab platform.

  • Distance-dependent defensive coloration in the poison frog Dendrobates tinctorius, Dendrobatidae
    2018
    Co-Authors: James B. Barnett, Constantine Michalis, Nicholas E. Scott-samuel, Innes C. Cuthill
    Abstract:

    Poison dart frogs provide classic examples of warning signals: potent toxins signaled by distinctive, conspicuous coloration. We show that, counterintuitively, the bright yellow and blue-black color of Dendrobates tinctorius (Dendrobatidae) also provides camouflage. Through computational modeling of predator vision, and a screen-based detection experiment presenting frogs at different spatial resolutions, we demonstrate that at close range the frog is highly detectable, but from a distance the colors blend together, forming effective camouflage. This result was corroborated with an in situ experiment, which found survival to be background-dependent, a feature more associated with camouflage than aposematism. Our results suggest that in D. tinctorius the distribution of pattern elements, and the particular colors expressed, act as a highly salient close range aposematic signal, while simultaneously minimizing detectability to distant observers.

  • image_data
    2018
    Co-Authors: James B. Barnett, Constantine Michalis, Nicholas E. Scott-samuel, Innes C. Cuthill
    Abstract:

    Image data associated with Barnett, J.B. et al. "Distance dependent defensive coloration in the poison frog Dendrobates tinctorius, Dendrobatidae

  • survival_data
    2018
    Co-Authors: James B. Barnett, Constantine Michalis, Nicholas E. Scott-samuel, Innes C. Cuthill
    Abstract:

    Survival data associated with Barnett, J.B. et al. "Distance dependent defensive coloration in the poison frog Dendrobates tinctorius, Dendrobatidae

Diann E. Gaalema - One of the best experts on this subject based on the ideXlab platform.

  • Sexual conditioning in the dyeing poison dart frog (Dendrobates tinctorius)
    2013
    Co-Authors: Diann E. Gaalema
    Abstract:

    Amphibian populations worldwide are currently in decline. One approach to preventing extinction of some of the affected species is to create assurance colonies. These sustainable populations might some day be used to reestablish wild populations. One issue with creating assurance colonies is successful breeding; often difficulties arise when attempting to breed exotic animals in zoological institutions. Sexual conditioning, a form of Pavlovian conditioning, has been shown to improve breeding behavior. In this study the efficacy of sexual conditioning to improve breeding behavior in the dyeing dart frog (Dendrobates tinctorius) was tested. Pairs of frogs were exposed to one of three conditions. In two conditions pairs were trained with a stimulus (a flashing green light) that was either predictive of (experimental) or independent of (active control) exposure to a member of the opposite sex. The third condition was a no-treatment control. After training all three conditions were given five days to interact. Members of the experimental condition showed shorter latencies to a variety of breeding behaviors and produced more eggs than those in the control conditions. The sexual conditioning procedure was successful in increasing breeding behavior in this population of frogs.