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[chytridiomycosis in amphibians--first report in europe].declining of amphibian populations is a worldwide phenomenon. a cutaneous mycosis as a cause of death in free-living amphibians as well as in captive ones due to an chytrid fungus (batrachochytrium dendrobatidis) was reported at first in 1998. this infections were reported hitherto from australia, north, central and south america. this is the first report on chytrid infections in captive anurans from europe. dendrobates auratus and d. pumilo imported from costa rica and p. vittatus imported from ...200011084755
production of polyclonal antibodies to batrachochytrium dendrobatidis and their use in an immunoperoxidase test for chytridiomycosis in amphibians.polyclonal antibodies were produced for diagnosing chytridiomycosis in amphibians. two sheep and 4 rabbits were inoculated with homogenized whole culture of batrachochytrium dendrobatidis in freund's complete adjuvant or triple adjuvant. antisera from all animals reacted strongly with all stages of b. dendrobatidis and stained the walls, cytoplasm, rhizoids and zoospores in an indirect immunoperoxidase test. significant cross-reactivity occurred only with some fungi in the chytridiomycota, and t ...200212033708
clinical diagnosis and treatment of epidermal chytridiomycosis in african clawed frogs (xenopus tropicalis).an investigation was conducted to determine the cause of morbidity and mortality in a collection of 55 adult male xenopus (silurana) tropicalis at the university of california, berkeley. more than 80% of affected frogs died during the epizootic. all frogs were anorectic and lethargic, had dark pigmentation and excess skin sloughing, and lacked a slime layer. histologic examination revealed severe hyperplastic and spongiotic dermatitis associated with colonization of the stratum corneum by large ...200212102573
activities of temporin family peptides against the chytrid fungus (batrachochytrium dendrobatidis) associated with global amphibian declines.temporin a and structurally related peptides produced in amphibian dermal granular glands and in wasp venom were tested for growth inhibition of batrachochytrium dendrobatidis, a pathogen associated with global amphibian declines. two natural amphibian temporins, a wasp temporin, and six synthetic analogs effectively inhibited growth. differences in potency due to amino acid substitution suggest that ability to penetrate membranes and form an alpha-helical structure is important for their effect ...200312604562
survival of batrachochytrium dendrobatidis in water: quarantine and disease control implications.amphibian chytridiomycosis is an emerging infectious disease of amphibians thought to be moved between countries by trade in infected amphibians. the causative fungus, batrachochytrium dendrobatidis, produces aquatic, motile zoospores; infections have been achieved in experiments by exposing amphibians to water containing zoospores. however, the ability of this fungus to survive in the environment in the absence of an amphibian host is unknown. we show that b. dendrobatidis will survive in tap w ...200312967488
use of immunohistochemistry to diagnose chytridiomycosis in dyeing poison dart frogs (dendrobates tinctorius).chytridiomycosis, caused by batrachochytrium dendrobatidis, is an emerging disease of both wild and captive amphibians, posing a threat to their survival in many parts of the world. as the disease can be difficult to diagnose on routine pathologic sections, the purpose of this study was to develop an additional method for visualization. to accomplish this, immunohistochemical staining was applied to histologic skin sections from four experimentally infected dyeing poison dart frogs (dendrobates ...200314567242
effect of season and temperature on mortality in amphibians due to chytridiomycosis.to investigate the distribution and incidence of chytridiomycosis in eastern australian frogs and to examine the effects of temperature on this disease.200415354853
a dna-based assay identifies batrachochytrium dendrobatidis in amphibians.chytridiomycosis caused by batrachochytrium dendrobatidis (chytridiomycota) has been implicated in declines of amphibian populations on four continents. we have developed a sensitive and specific polymerase chain reaction-based assay to detect this pathogen. we isolated b. dendrobatidis from captive and wild amphibians collected across north america and sequenced the internal transcribed spacer regions of the rdna cassette of multiple isolates. we identified two primers (bd1a and bd2a) that are ...200415465708
origin of the amphibian chytrid fungus.the sudden appearance of chytridiomycosis, the cause of amphibian deaths and population declines in several continents, suggests that its etiologic agent, the amphibian chytrid batrachochytrium dendrobatidis, was introduced into the affected regions. however, the origin of this virulent pathogen is unknown. a survey was conducted of 697 archived specimens of 3 species of xenopus collected from 1879 to 1999 in southern africa in which the histologic features of the interdigital webbing were analy ...200415663845
antimicrobial peptide defenses against chytridiomycosis, an emerging infectious disease of amphibian populations.chytridiomycosis, an emerging infectious disease (eid) of the skin caused by the chytrid fungus, batrachochytrium dendrobatidis, has been linked with continuing amphibian population declines in the western usa, central america, europe, africa, and australia. genetic analysis suggests that b. dendrobatidis is a recently emerged pathogen. this article reviews the biology of this pathogenic chytrid and the evidence for chytridiomycosis as a cause of declines in amphibian populations worldwide. data ...200515784290
population trends associated with skin peptide defenses against chytridiomycosis in australian frogs.many species of amphibians in the wet tropics of australia have experienced population declines linked with the emergence of a skin-invasive chytrid fungus, batrachochytrium dendrobatidis. an innate defense, antimicrobial peptides produced by granular glands in the skin, may protect some species from disease. here we present evidence that supports this hypothesis. we tested ten synthesized peptides produced by australian species, and natural peptide mixtures from five queensland rainforest speci ...200616205955
antimicrobial peptide defenses of the mountain yellow-legged frog (rana muscosa).the mountain yellow-legged frog (rana muscosa) inhabits high elevation lakes in california that are largely undisturbed by human activities. in spite of this habitation in remote sites, populations continue to decline. although predation by non-native fish is one cause for declines, some isolated populations in fishless lakes are suffering new declines. one possible cause of the current wave of declines is the introduction of the pathogenic chytrid fungus (batrachochytrium dendrobatidis) which i ...200616330099
widespread amphibian extinctions from epidemic disease driven by global warming.as the earth warms, many species are likely to disappear, often because of changing disease dynamics. here we show that a recent mass extinction associated with pathogen outbreaks is tied to global warming. seventeen years ago, in the mountains of costa rica, the monteverde harlequin frog (atelopus sp.) vanished along with the golden toad (bufo periglenes). an estimated 67% of the 110 or so species of atelopus, which are endemic to the american tropics, have met the same fate, and a pathogenic c ...200616407945
virulence of the amphibian chytrid fungus batrachochytium dendrobatidis varies with the strain.although mortality in 3 groups of 15 green tree frogs litoria caerulea exposed to 3 isolates of batrachochytrium dendrobatidis was 100%, time to death varied with isolate, highlighting the importance of strain and/or passage history in pathogenicity studies and possibly in the epidemiology of chytridiomycosis. a standard naming scheme for isolates of b. dendrobatidis is proposed.200516465833
life cycle stages of the amphibian chytrid batrachochytrium dendrobatidis.an overview of the morphology and life cycle of batrachochytrium dendrobatidis, the cause of chytridiomycosis of amphibians, is presented. we used a range of methods to examine stages of the life cycle in culture and in frog skin, and to assess ultrastructural pathology in the skin of 2 frogs. methods included light microscopy, transmission electron microscopy with conventional methods as well as high pressure freezing and freeze substitution, and scanning electron microscopy with critical point ...200516465834
distribution of batrachochytrium dendrobatidis and pathology in the skin of green tree frogs litoria caerulea with severe chytridiomycosis.although histopathology is used routinely for diagnosis of chytridiomycosis in live and dead amphibians, there are no quantitative data on the distribution of the causative fungus, batrachochytrium dendrobatidis, in the skin. we performed quantitative histological examinations on 6 sites on the body and 4 toes of 10 free-ranging adult green tree frogs litoria caerulea found recently dead or dying from chytridiomycosis. large numbers of sporangia occurred in all areas of ventral skin and toes; on ...200516465835
ms-222 (tricaine methane sulfonate) does not kill the amphibian chytrid fungus batrachochytrium dendrobatidis.ms-222 (tricaine methane sulfonate) is an agent commonly used to anaesthetise or euthanize amphibians used in experiments. it is administered by immersing the animal to allow absorption through the skin. chytridiomycosis is an important disease of amphibians and research involves experiments with live animals. batrachochytrium dendrobatidis, the fungus which causes chytridiomycosis, is located in the skin and therefore the organism should come into contact with ms-222 when it is used. b. dendrob ...200516465838
emerging infectious disease and the loss of biodiversity in a neotropical amphibian community.pathogens rarely cause extinctions of host species, and there are few examples of a pathogen changing species richness and diversity of an ecological community by causing local extinctions across a wide range of species. we report the link between the rapid appearance of a pathogenic chytrid fungus batrachochytrium dendrobatidis in an amphibian community at el copé, panama, and subsequent mass mortality and loss of amphibian biodiversity across eight families of frogs and salamanders. we describ ...200616481617
predicted disease susceptibility in a panamanian amphibian assemblage based on skin peptide defenses.chytridiomycosis is an emerging infectious disease of amphibians caused by a chytrid fungus, batrachochytrium dendrobatidis. this panzootic does not equally affect all amphibian species within an assemblage; some populations decline, others persist. little is known about the factors that affect disease resistance. differences in behavior, life history, biogeography, or immune function may impact survival. we found that an innate immune defense, antimicrobial skin peptides, varied significantly a ...200616870844
first case of ranavirus-associated morbidity and mortality in natural populations of the south american frog atelognathus patagonicus.atelognathus patagonicus is an endangered leptodactylid frog endemic to a small region in and around laguna blanca national park in northern patagonia, argentina. all of the lakes and small ponds of the region (except laguna blanca itself) contain a. patagonicus and in all but one of these lakes the species shows clinical signs of a previously undiagnosed disease, the characteristics of which suggested a ranavirus. we collected symptomatic and asymptomatic a. patagonicus frogs and tadpoles from ...200617067077
multiple, non-allelic, intein-coding sequences in eukaryotic rna polymerase genes.inteins are self-splicing protein elements. they are translated as inserts within host proteins that excise themselves and ligate the flanking portions of the host protein (exteins) with a peptide bond. they are encoded as in-frame insertions within the genes for the host proteins. inteins are found in all three domains of life and in viruses, but have a very sporadic distribution. only a small number of intein coding sequences have been identified in eukaryotic nuclear genes, and all of these a ...200617069655
climate change and outbreaks of amphibian chytridiomycosis in a montane area of central spain; is there a link?amphibian species are declining at an alarming rate on a global scale in large part owing to an infectious disease caused by the chytridiomycete fungus, batrachochytrium dendrobatidis. this disease of amphibians has recently emerged within europe, but knowledge of its effects on amphibian assemblages remains poor. importantly, little is known about the environmental envelope that is associated with chytridiomycosis in europe and the potential for climate change to drive future disease dynamics. ...200717148254
diagnostic assays and sampling protocols for the detection of batrachochytrium dendrobatidis.batrachochytrium dendrobatidis is a fungus belonging to the phylum chytridiomycota, class chytridiomycetes, order chytridiales, and is the highly infectious aetiological agent responsible for a potentially fatal disease, chytridiomycosis, which is currently decimating many of the world's amphibian populations. the fungus infects 2 amphibian orders (anura and caudata), 14 families and at least 200 species and is responsible for at least 1 species extinction. whilst the origin of the agent and rou ...200717330737
on the biological relevance of a single batrachochytrium dendrobatidis zoospore: a reply to smith. 200717330746
removal of nonnative fish results in population expansion of a declining amphibian (mountain yellow-legged frog, rana muscosa).the mountain yellow-legged frog (rana muscosa) was once a common inhabitant of the sierra nevada (california, usa), but has declined precipitously during the past century due in part to the introduction of nonnative fish into naturally fishless habitats. the objectives of the current study were to describe (1) the effect of fish removal from three lakes (located in two watersheds) on the small, remnant r. muscosa populations inhabiting those lakes, and (2) the initial development of metapopulati ...200717396156
surveillance for batrachochytrium dendrobatidis using mixophyes (anura: myobatrachidae) larvae.fourteen populations of anuran larvae (tadpoles), including three populations of the endangered fleay's barred frog (mixophyes fleayi) and 11 populations of the common great barred frog (mixophyes fasciolatus), in creek sites in the southeast region of queensland were selected. site selection was based on a history (within the district) of adult frog population declines and/or disappearances or records of infection of adult frogs or larvae by batrachochytrium dendrobatidis. larvae were collected ...200717347393
chytridiomycosis in two species of telmatobius (anura: leptodactylidae) from argentina.dead specimens of telmatobius atacamensis and t. pisanoi were found in 2 localities in northwestern argentina. the diagnosis was positive for chytridiomycosis caused by batrachochytrium dendrobatidis. zoosporangia were identified in different stages: immature, mature with zoospores, empty and collapsed. this is the second report of chytridiomycosis in argentina but the first one involving highly endangered species.200617260836
the emerging amphibian pathogen batrachochytrium dendrobatidis globally infects introduced populations of the north american bullfrog, rana catesbeiana.batrachochytrium dendrobatidis is the chytridiomycete fungus which has been implicated in global amphibian declines and numerous species extinctions. here, we show that introduced north american bullfrogs (rana catesbeiana) consistently carry this emerging pathogenic fungus. we detected infections by this fungus on introduced bullfrogs from seven of eight countries using both pcr and microscopic techniques. only native bullfrogs from eastern canada and introduced bullfrogs from japan showed no s ...200617148429
relationships among size, development, and batrachochytrium dendrobatidis infection in african tadpoles.the fungal pathogen batrachochytrium dendrobatidis contributes to the global decline of amphibians. although mortality from b. dendrobatidis infections occurs primarily in postmetamorphic individuals, infected tadpoles may suffer reduced growth and developmental rates as a result of oral chytridiomycosis, possibly affecting adult fitness. we conducted a field study in which we examined south african tadpoles for oral chytridiomycosis and compared the body sizes of infected and uninfected individ ...200717432045
survival of three species of anuran metamorphs exposed to uv-b radiation and the pathogenic fungus batrachochytrium dendrobatidis.when exploring the possible factors contributing to population declines, it is necessary to consider multiple, interacting environmental stressors. here, we investigate the impact of 2 factors, ultraviolet radiation and disease, on the survival of anuran amphibians. exposure to ultraviolet-b (uv-b) radiation increases mortality and results in various sub-lethal effects for many amphibian species. infectious diseases can also negatively impact amphibian populations. in this study, we exposed meta ...200617140139
ecology: the proximate cause of frog declines?pounds et al. argue that global warming contributes to amphibian declines by encouraging outbreaks of the chytrid fungus batrachochytrium dendrobatidis. although our findings agree with the climate-linked epidemic hypothesis, this pathogen is probably not the only proximate factor in such cases: in the trasimeno lake area of umbria in central italy, for example, the water frog rana lessonae first declined in the late 1990s, yet chytridiomycosis was not observed until 2003 (refs 5, 6). here we sh ...200717538572
peptides with differential cytolytic activity from skin secretions of the lemur leaf frog hylomantis lemur (hylidae: phyllomedusinae).two peptides with differential cytolytic activity against bacteria, a fungus pathogenic to amphibians, and mammalian cells were isolated from norepinephrine-stimulated skin secretions of the lemur leaf frog hylomantis lemur boulenger, 1882. dermaseptin-l1 (glwskikeaakaagkaalnavtglvnqgdqps) was active against the gram-negative bacterium escherichia coli (mic=8 microm) but inactive against the gram-positive bacterium staphylococcus aureus. this peptide inhibited growth of zoospores of the chytrid ...200717561225
quantifying the disease transmission function: effects of density on batrachochytrium dendrobatidis transmission in the mountain yellow-legged frog rana muscosa.1. chytridiomycosis is an emerging infectious disease of amphibians, caused by the fungal pathogen batrachochytrium dendrobatidis, which has been implicated recently in population declines and possible extinctions throughout the world. 2. the transmission rate of this pathogen was quantified in the mountain yellow-legged frog rana muscosa through laboratory and field experiments, and a maximum likelihood approach was used to determine the form of the transmission function that was best supported ...200717584377
strain differences in the amphibian chytrid batrachochytrium dendrobatidis and non-permanent, sub-lethal effects of infection.the chytrid fungus batrachochytrium dendrobatidis (bd) is likely the cause of numerous recent amphibian population declines worldwide. while the fungus is generally highly pathogenic to amphibians, hosts express a wide range of responses to infection, probably due to variation among hosts and environmental conditions, but possibly also due to variation in bd. we investigated variation in bd by exposing standardized host groups to 2 bd strains in a uniform environment. all exposed frogs became in ...200717629114
population genetics of the frog-killing fungus batrachochytrium dendrobatidis.global amphibian decline by chytridiomycosis is a major environmental disaster that has been attributed to either recent fungal spread or environmental change that promotes disease. here, we present a population genetic comparison of batrachochytrium dendrobatidis isolates from an intensively studied region of frog decline, the sierra nevada of california. in support of a novel pathogen, we find low diversity, no amphibian-host specificity, little correlation between fungal genotype and geograph ...200717693553
prevalence of batrachochytrium dendrobatidis in american bullfrog and southern leopard frog larvae from wetlands on the savannah river site, south carolina.batrachochytrium dendrobatidis, an aquatic fungus, has been linked to recent amphibian population declines. few surveys have assessed b. dendrobatidis infections in areas where the disease is suggested to be less virulent and population declines have not been observed, such as southeastern north america. although adult rana catesbeiana and rana sphenocephala from the savannah river site, south carolina collected in 1979 and 1982 were identified as having b. dendrobatidis, it is unknown whether t ...200717699083
chytrid fungus in frogs from an equatorial african montane forest in western uganda.batrachochytrium dendrobatidis, the causative agent of chytridiomycosis, was found in 24 of 109 (22%) frogs from kibale national park, western uganda, in january and june 2006, representing the first account of the fungus in six species and in uganda. the presence of b. dendrobatidis in an equatorial african montane forest raises conservation concerns, considering the high amphibian diversity and endemism characteristic of such areas and their ecological similarity to other regions of the world ...200717699093
quantitative measurement of batrachochytrium dendrobatidis in amphibian skin.the ability to quantify infections provides a tool with which to perform comparative pathological research. the need exists for a simplistic standard method to compare infection levels of batrachochytrium dendrobatidis, a major cause of global amphibian declines. through examination of skin sloughs of the cape river frog afrana fuscigula, we present an accessible method that not only provides quantitative measurements of b. dendrobatidis, but also provides information that increases the confiden ...200617140138
detection of batrachochytrium dendrobatidis in eleutherodactylus fitzingeri: effects of skin sample location and histologic stain.batrachochytrium dendrobatidis is a fungal pathogen that has been implicated in amphibian declines worldwide. histopathologic techniques have been used to diagnose the disease, but their sensitivity has not been determined. it is also unclear whether the probability of detection varies between skin samples derived from different body parts. we examined 24 fitzinger's rainfrogs (eleutherodactylus fitzingeri) with chytridiomycosis. this is a common frog species with a broad range and high abundanc ...200616870852
possible modes of dissemination of the amphibian chytrid batrachochytrium dendrobatidis in the environment.amphibian chytridiomycosis caused by batrachochytrium dendrobatidis has spread at an alarming rate over large distances throughout sensitive frog populations in eastern australia, central america and new zealand. infected amphibians and contaminated water are implicated in translocation, but other vectors are unknown. through in vitro studies we show that potential means of translocation may be moist soil and bird feathers. b. dendrobatidis survived for up to 3 mo in sterile, moist river sand wi ...200516119886
environmental detection of batrachochytrium dendrobatidis in a temperate climate.the aetiological agent of amphibian chytridiomycosis batrachochytrium dendrobatidis is a primary cause of amphibian population declines. current surveillance is based on the detection of b. dendrobatidis in its host but in vitro work suggests infective stages may survive in the abiotic environment for at least 3 mo. we describe here a surveillance system using filtration and quantitative pcr that can detect b. dendrobatidis in small (< 1 l) volumes of water. after assessing the analytical sensit ...200717972751
co-localisation of batrachochytrium dendrobatidis and keratin for enhanced diagnosis of chytridiomycosis in frogs.chytridiomycosis is a disease of post-metamorphic frogs caused by the fungus batrachochytrium dendrobatidis and is associated with large declines in frog populations on a global scale. b. dendrobatidis is found only in the keratinised tissues, which include the mouthparts of healthy tadpoles. the epidermis of infected post-metamorphic frogs is thickened (hyperkeratosis) and the superficial layer can sometimes slough. diagnosis is most commonly performed on stained sections of toe clips or ventra ...200415584414
evaluation of tadpole mouthpart depigmentation as a diagnostic test for infection by batrachochytrium dendrobatidis for four california anurans.the objective of this study was to evaluate the utility of gross morphologic examination of larval mouthpart defects as a diagnostic screening test to detect batrachochytrium dendrobatidis infection in four california, usa, anuran species. we examined mouthparts of 2,034 tadpoles of bufo boreas, pseudacris regilla, and rana catesbeiana collected in 2003 and 2004 and bufo canorus collected in 2004. data were recorded for three morphologic features: upper toothrows, lower toothrows, and combined j ...200717984265
transmission of batrachochytrium dendrobatidis within and between amphibian life stages.chytridiomycosis is an emerging infectious disease caused by the chytrid fungus batrachochytrium dendrobatidis, which has been implicated in amphibian declines worldwide. the mountain yellow-legged frog rana muscosa is a declining amphibian species that can be infected by b. dendrobatidis; however, transmission between conspecifics has not been documented. here, we present experimental evidence that r. muscosa tadpoles can be infected by fungal zoospores and that they can transmit infection to e ...200415584413
the identification of 2,4-diacetylphloroglucinol as an antifungal metabolite produced by cutaneous bacteria of the salamander plethodon cinereus.beneficial bacteria that live on salamander skins have the ability to inhibit pathogenic fungi. our study aimed to identify the specific chemical agent(s) of this process and asked if any of the antifungal compounds known to operate in analogous plant-bacteria-fungi systems were present. crude extracts of bacteria isolated from salamander skin were exposed to hplc, uv-vis, gc-ms, and hr-ms analyses. these investigations show that 2,4-diacetylphloroglucinol is produced by the bacteria isolate lys ...200818058176
development of an assay for testing the antimicrobial activity of skin peptides against the amphibian chytrid fungus (batrachochytrium dendrobatidis) using xenopus laevis.this report describes the preliminary characterization of a bioassay for testing the antimicrobial activity of amphibian skin peptides against the chytrid fungus, batrachochytrium dendrobatidis. peptide secretions from xenopus laevis were induced by subcutaneous injections of norepinephrine. partially purified secretions were quantified and incubated at various dilutions with 10(7) cells/ml of freshly isolated zoospores for 7 days. peptide bioactivity was measured as cell growth inhibition over ...200818067960
endemic infection of the amphibian chytrid fungus in a frog community post-decline.the chytrid fungus batrachochytrium dendrobatidis has been implicated in the decline and extinction of numerous frog species worldwide. in queensland, australia, it has been proposed as the cause of the decline or apparent extinction of at least 14 high-elevation rainforest frog species. one of these, taudactylus eungellensis, disappeared from rainforest streams in eungella national park in 1985-1986, but a few remnant populations were subsequently discovered. here, we report the analysis of b. ...200415502873
rapid quantitative detection of chytridiomycosis (batrachochytrium dendrobatidis) in amphibian samples using real-time taqman pcr assay.batrachochytrium dendrobatidis is a major pathogen of frogs worldwide, associated with declines in amphibian populations. diagnosis of chytridiomycosis to date has largely relied upon histological and immunohistochemical examination of toe clips. this technique is invasive and insensitive particularly at early stages of infection when treatment may be possible. we have developed a real-time pcr taqman assay that can accurately detect and quantify one zoospore in a diagnostic sample. this assay w ...200415460858
chytridiomycosis impacts predator-prey interactions in larval amphibian communities.despite ecologists increasingly recognizing pathogens as playing significant roles in community dynamics, few experimental studies have quantified patterns of disease impacts on natural systems. amphibians are experiencing population declines, and a fungal pathogen ( batrachochytrium dendrobatidis; chytridiomycota) is a suspected causal agent in many declines. we studied the effects of a pathogenic fungus on community interactions between the gray treefrog, hyla chrysoscelis, and eastern newts, ...200415235903
fungicidal effects of chemical disinfectants, uv light, desiccation and heat on the amphibian chytrid batrachochytrium dendrobatidis.the efficacy of a number of disinfection treatments was tested on in vitro cultures of the fungus batrachochytrium dendrobatidis, the causative agent of chytridiomycosis in amphibians. the aim was to evaluate the fungicidal effects of chemical disinfectants, sterilising ultraviolet (uv) light, heat and desiccation, using methods that were feasible for either disinfection in the field, in amphibian husbandry or in the laboratory. the chemical disinfectants tested were: sodium chloride, household ...200314960039
antimicrobial peptide defenses in the salamander, ambystoma tigrinum, against emerging amphibian pathogens.skin peptides were collected from living ambystoma tigrinum larvae and adults and tested against two emerging pathogens, batrachochytrium dendrobatidis and the ambystoma tigrinum virus (atv), as well as bacteria isolated from a. tigrinum. natural mixtures of skin peptides were found to inhibit growth of b. dendrobatidis, staphylococcus aureus, and klebsiella sp., but activity against atv was unpredictable. skin peptides collected from salamanders held at three environmentally relevant temperatur ...200818436656
emerging pathogen of wild amphibians in frogs (rana catesbeiana) farmed for international trade.chytridiomycosis is an emerging disease responsible for a series of global declines and extinctions of amphibians. we report the causative agent, batrachochytrium dendrobatidis, in north american bullfrogs (rana catesbeiana) farmed for the international restaurant trade. our findings suggest that international trade may play a key role in the global dissemination of this and other emerging infectious diseases in wildlife.200312967500
growth characteristics and enzyme activity in batrachochytrium dendrobatidis isolates.batrachochytrium dendrobatidis is a member of the phylum chytridiomycota and the causative organism chytridiomycosis, a disease of amphibians associated with global population declines and mass mortality events. the organism targets keratin-forming epithelium in adult and larval amphibians, which suggests that keratinolytic activity may be required to infect amphibian hosts. to investigate this hypothesis, we tested 10 isolates of b. dendrobatidis for their ability to grow on a range of keratin- ...200818568420
life-history trade-offs influence disease in changing climates: strategies of an amphibian pathogen.life-history trade-offs allow many animals to maintain reproductive fitness across a range of climatic conditions. when used by parasites and pathogens, these strategies may influence patterns of disease in changing climates. the chytrid fungus, batrachochytrium dendrobatidis, is linked to global declines of amphibian populations. short-term growth in culture is maximal at 17 degrees-25 degrees c. this has been used in an argument that global warming, which increases the time that amphibians spe ...200818589527
chytridiomycosis survey in wild and captive mexican amphibians.mexico, a rich country in terms of amphibian diversity, hosts about 375 described species. population declines have been documented for several species where it is evident that their habitat is being destroyed or modified. however, other species which inhabit pristine areas are declining as well. it has been suggested that the chytrid fungus batrachochytrium dendrobatidis (b.d.) may be one of the causes of the enigmatic declines in mexico. we surveyed a total of 45 localities, in 12 states acros ...200818648793
emerging disease of amphibians cured by elevated body temperature.the emerging infectious disease chytridiomycosis is thought to have contributed to many of the recent alarming declines in amphibian populations. mortalities associated with these declines have often occurred during cooler seasons and at high elevations, suggesting that environmental temperature may be an important factor in disease emergence. we found that thermal environment affects the progress of the disease, and that housing frogs litoria chloris at an environmental temperature of 37 degree ...200312887256
multilocus sequence typing suggests the chytrid pathogen of amphibians is a recently emerged clone.chytridiomycosis is a recently identified fungal disease associated with global population declines of frogs. although the fungus, batrachochytrium dendrobatidis, is considered an emerging pathogen, little is known about its population genetics, including the origin of the current epidemic and how this relates to the dispersal ability of the fungus. in this study, we use multilocus sequence typing to examine genetic diversity and relationships among 35 fungal strains from north america, africa a ...200312535090
detection of chytridiomycosis caused by batrachochytrium dendrobatidis in the endangered sardinian newt (euproctus platycephalus) in southern sardinia, italy.the chytridiomycete fungus batrachochytrium dendrobatidis is known to be focally distributed across europe, but has only been linked to "chytridiomycosis at a few locations in spain. here we report the second occurrence of chytridiomycosis in european amphibians. we found a population of endangered sardinian newts (euproctus platycephalus) exhibiting clinical signs of disease including loss of digits and patchy, discolored skin. molecular examination of skin samples tested positive for b. dendro ...200818689659
antimicrobial peptide defenses of the tarahumara frog, rana tarahumarae.populations of the tarahumara frog rana tarahumarae have decreased markedly in recent years in the northern part of their range. infection by the chytrid fungus batrachochytrium dendrobatidis has been implicated in these declines. to determine whether antimicrobial peptides in the skin provide protection against this pathogen, norepinephrine-stimulated skin secretions were tested for their ability to inhibit growth of b. dendrobatidis in vitro. after concentration, crude mixtures of skin peptide ...200212237127
activity of antimicrobial skin peptides from ranid frogs against batrachochytrium dendrobatidis, the chytrid fungus associated with global amphibian declines.accumulating evidence suggests that a chytrid fungus, batrachochytrium dendrobatidis, is responsible for recent declines in amphibian populations in australia, central america, europe, and north america. because the chytrid infects the keratinized epithelium of the skin, we investigated the possible role of antimicrobial peptides produced in the skin as inhibitors of infection and growth. we show here that 10 peptides representing eight families of peptides derived from north american ranid frog ...200211906726
chytridiomycosis in native arizona frogs.twenty-seven adult/sub-adult lowland leopard frogs (rana yavapaiensis), two larval lowland leopard frogs, two adult chirichahua leopard frogs (rana chiricahuensis), and two adult canyon tree frogs (hyla arenicolor) collected from populations experiencing mortality events at eight sites were found to have characteristic lesions of chytrid fungus infection (batrachochytrium dendrobatidis). the mortalities occurred during december 1992 and between october and february in 1997-98 and december and fe ...200211838218
antimicrobial peptide defenses against pathogens associated with global amphibian declines.global declines of amphibian populations are a source of great concern. several pathogens that can infect the skin have been implicated in the declines. the pathogen most frequently associated with recent die-offs is a chytrid fungus, batrachochytrium dendrobatidis. a second fungus, basidiobolus ranarum, was isolated from declining populations of wyoming toads. a third pathogen, aeromonas hydrophila, is an opportunistic bacterium found in healthy frogs, but capable of inducing disease. among the ...200211687264
experimental transmission of cutaneous chytridiomycosis in dendrobatid frogs.in a series of three experiments during march-october, 1998, two species of captive-bred poison dart frogs (dendrobates tinctorius and d. auratus) were exposed to batrachochytrium dendrobatidis, a recently-described chytridiomycete fungus (chytrid) that was originally isolated from a blue poison dart frog (d. azureus). all frogs exposed to the chytrids developed a fatal skin disease, whereas none of the control frogs developed skin lesions. the most consistent clinical sign in chytrid-exposed fr ...200111272482
cryo-archiving of batrachochytrium dendrobatidis and other chytridiomycetes.batrachochytrium dendrobatidis is a major pathogen of frogs worldwide. it has been associated with catastrophic declines of frog populations including those in pristine habitats in queensland, australia. to facilitate genetic and disease studies of this fungus and related species, it is essential to have a reliable long-term storage method to maintain genetic integrity of isolates. we have adapted well-established techniques used for the long-term storage of tissue-culture cell lines to the pres ...200314524502
concurrent infection with ranavirus, batrachochytrium dendrobatidis, and aeromonas in a captive anuran colony.four species (dendrobates auratus, phyllobates terribilis, pyxicephalus adspersus, and rhacophorus dennysi) of captive anurans with a clinical history of lethargy and inappetence were found dead and were submitted for necropsy. gross lesions included irregular patches of sloughed skin and rare dermal ulcerations. histologic findings included epidermal proliferation that was most pronounced on the digits and that included intracytoplasmic chytrid organisms. bacteria were often associated with the ...200818817009
global gene expression profiles for life stages of the deadly amphibian pathogen batrachochytrium dendrobatidis.amphibians around the world are being threatened by an emerging pathogen, the chytrid fungus batrachochytrium dendrobatidis (bd). despite intensive ecological study in the decade since bd was discovered, little is known about the mechanism by which bd kills frogs. here, we compare patterns of global gene expression in controlled laboratory conditions for the two phases of the life cycle of bd: the free-living zoospore and the substrate-embedded sporangia. we find zoospores to be transcriptionall ...200818852473
latitudinal variation in the prevalence and intensity of chytrid (batrachochytrium dendrobatidis) infection in eastern australia.chytridiomycosis is a recently emerged, infectious skin disease of amphibians that has been linked directly to mass mortalities, population declines, and species extinctions worldwide. an understanding of the factors that limit the distribution and abundance of batrachochytrium dendrobatidis (the etiological agent of chytridiomycosis) is urgently required. we conducted disease surveys at 31 lowland sites distributed north-south along 2315 km of the australian east coast that encompassed 20.8 deg ...200717883493
emerging infectious disease as a proximate cause of amphibian mass mortality.a newly discovered infectious disease of amphibians, chytridiomycosis, caused by the fungal pathogen batrachochytrium dendrobatidis, is implicated in population declines and possible extinctions throughout the world. the purpose of our study was to examine the effects of b. dendrobatidis on the mountain yellow-legged frog (rana muscosa) in the sierra nevada of california (usa). we (1) quantified the prevalence and incidence of b. dendrobatidis through repeat surveys of several hundred r. muscosa ...200616922318
evaluating the links between climate, disease spread, and amphibian declines.human alteration of the environment has arguably propelled the earth into its sixth mass extinction event and amphibians, the most threatened of all vertebrate taxa, are at the forefront. many of the worldwide amphibian declines have been caused by the chytrid fungus, batrachochytrium dendrobatidis (bd), and two contrasting hypotheses have been proposed to explain these declines. positive correlations between global warming and bd-related declines sparked the chytrid-thermal-optimum hypothesis, ...200818987318
molecular toolkit unlocks life cycle of the panzootic amphibian pathogen batrachochytrium dendrobatidis. 200818997006
a non-lethal technique for detecting the chytrid fungus batrachochytrium dendrobatidis on tadpoles.batrachochytrium dendrobatidis (bd) infection on post-metamorphic frogs and salamanders is commonly diagnosed using polymerase chain reaction (pcr) of skin scrapings taken with mildly abrasive swabs. the technique is sensitive, non-lethal, and repeatable for live animals. tadpoles are generally not sampled by swabbing but are usually killed and their mouthparts excised to test for the pathogen. we evaluated a technique for non-lethal bd diagnosis using quantitative pcr (qpcr) on swabs scraped ov ...200617067076
persistence of the emerging pathogen batrachochytrium dendrobatidis outside the amphibian host greatly increases the probability of host extinction.pathogens do not normally drive their hosts to extinction; however, batrachochytrium dendrobatidis, which causes amphibian chytridiomycosis, has been able to do so. theory predicts that extinction can be caused by long-lived or saprobic free-living stages. the hypothesis that such a stage occurs in b. dendrobatidis is supported by the recent discovery of an apparently encysted form of the pathogen. to investigate the effect of a free-living stage of b. dendrobatidis on host population dynamics, ...200818048287
widespread occurrence of the amphibian chytrid fungus batrachochytrium dendrobatidis in the southeastern usa.from 1999 to 2006, we sampled > 1200 amphibians for the fungal pathogen batrachochytrium dendrobatidis (bd) at 30 sites in the southeastern usa. using histological techniques or pcr assays, we detected chytrid infection in 10 species of aquatic-breeding amphibians in 6 states. the prevalence of chytrid infection was 17.8% for samples of postmetamorphic amphibians examined using skin swab-pcr assays (n = 202 samples from 12 species at 4 sites). in this subset of samples, anurans had a much higher ...200819062748
riding the wave: reconciling the roles of disease and climate change in amphibian declines.we review the evidence for the role of climate change in triggering disease outbreaks of chytridiomycosis, an emerging infectious disease of amphibians. both climatic anomalies and disease-related extirpations are recent phenomena, and effects of both are especially noticeable at high elevations in tropical areas, making it difficult to determine whether they are operating separately or synergistically. we compiled reports of amphibian declines from lower central america and andean south america ...200818366257
effects of chytrid and carbaryl exposure on survival, growth and skin peptide defenses in foothill yellow-legged frogs.environmental contaminants and disease may synergistically contribute to amphibian population declines. sub-lethal levels of contaminants can suppress amphibian immune defenses and, thereby, may facilitate disease outbreaks. we conducted laboratory experiments on newly metamorphosed foothill yellow-legged frogs (rana boylii) to determine whether sublethal exposure to the pesticide carbaryl would increase susceptibility to the pathogenic chytrid fungus batrachochytrium dendrobatidis that is widel ...200717396672
first report of spontaneous chytridiomycosis in frogs in asia.this is the first report of amphibian chytridiomycosis in asia. we discovered a lethal outbreak in japan, among 45 exotic frogs from 18 species kept for breeding by a private owner. of these 45 frogs, 16 died and another 7 were found to be infected by chytrid fungus batrachochytrium dendrobatidis (bd) but survived after treatment. bd was detected in frogs from 9 species (lepidobatrachus laevis, ceratophrys cornuta, c. cranwelli, c. ornata, c. calcarata, chacophrys pierotti, occidozyga lima, lept ...200819149379
first record of chytridiomycosis in bolivia (rhinella quechua; anura: bufonidae).the finding of tadpoles of rhinella quechua (huayramayu river, carrasco national park, cochabamba, bolivia) with oral abnormalities caused by batrachochytrium dendrobatidis constitutes the first record of this fungal infection reported for bolivian amphibians.200819149380
proteomic and phenotypic profiling of the amphibian pathogen batrachochytrium dendrobatidis shows that genotype is linked to virulence.population genetics of the amphibian pathogen batrachochytrium dendrobatidis (bd) show that isolates are highly related and globally homogenous, data that are consistent with the recent epidemic spread of a previously endemic organism. highly related isolates are predicted to be functionally similar due to low levels of heritable genetic diversity. to test this hypothesis, we took a global panel of bd isolates and measured (i) the genetic relatedness among isolates, (ii) proteomic profiles of is ...200919161465
behaviour of australian rainforest stream frogs may affect the transmission of chytridiomycosis.the amphibian disease chytridiomycosis, caused by the pathogen batrachochytrium dendrobatidis, has been implicated in mass mortalities, population declines and extinctions of amphibians around the world. in almost all cases, amphibian species that have disappeared or declined due to chytridiomycosis coexist with non-declining species. one reason why some species decline from chytridiomycosis and others do not may be interspecific differences in behaviour. host behaviour could either facilitate o ...200717933392
quantitative pcr detection of batrachochytrium dendrobatidis dna from sediments and water.the fungal pathogen batrachochytrium dendrobatidis (bd) causes chytridiomycosis, a disease implicated in amphibian declines on 5 continents. polymerase chain reaction (pcr) primer sets exist with which amphibians can be tested for this disease, and advances in sampling techniques allow non-invasive testing of animals. we developed filtering and pcr based quantitative methods by modifying existing pcr assays to detect bd dna in water and sediments, without the need for testing amphibians; we test ...200717933393
batrachochytrium dendrobatidis and chytridiomycosis in anuran amphibians of colombia.in order to investigate the possible presence of the chytrid fungus batrachochytrium dendrobatidis (chytridiomycota: chytridiales) in frogs (amphibia: anura) of colombia, we made a retrospective examination of formalin-fixed specimens preserved in natural history collections. using the staining technique of hematoxylin and eosin to identify b. dendrobatidis in histological slices, we found evidence of the fungus in 3 of the 53 frog species examined from a total of 672 specimens collected in 17 d ...200818648794
presence of the chytrid fungus batrachochytrium dendrobatidis in populations of the critically endangered frog mannophryne olmonae in tobago, west indies.the emerging infectious disease chytridiomycosis is prevalent in central and south america, and has caused catastrophic declines of amphibian populations in the neotropics. the responsible organism, batrachochytrium dendrobatidis, has been recorded on three west indian islands, but the whole of the caribbean region is predicted to offer a suitable environment for the disease. monitoring the spread of chytridiomycosis is thus a priority in this region, which has exceptionally high levels of amphi ...200818648795
comparative evolutionary histories of the fungal chitinase gene family reveal non-random size expansions and contractions due to adaptive natural selection.gene duplication and loss play an important role in the evolution of novel functions and for shaping an organism's gene content. recently, it was suggested that stress-related genes frequently are exposed to duplications and losses, while growth-related genes show selection against change in copy number. the fungal chitinase gene family constitutes an interesting case study of gene duplication and loss, as their biological roles include growth and development as well as more stress-responsive fu ...200819204807
skin microbes on frogs prevent morbidity and mortality caused by a lethal skin fungus.emerging infectious diseases threaten human and wildlife populations. altered ecological interactions between mutualistic microbes and hosts can result in disease, but an understanding of interactions between host, microbes and disease-causing organisms may lead to management strategies to affect disease outcomes. many amphibian species in relatively pristine habitats are experiencing dramatic population declines and extinctions due to the skin disease chytridiomycosis, which is caused by the ch ...200919322245
retreat sites of rain forest stream frogs are not a reservoir for batrachochytrium dendrobatidis in northern queensland, australia.chytridiomycosis is a potentially fatal disease of amphibians caused by batrachochytrium dendrobatidis, and is implicated in declines and extinctions of amphibian populations and species around the world. to cause local host extinction, a disease organism must persist at low host densities. one mechanism that could facilitate this is the ability to persist in the environment. in the laboratory, b. dendrobatidis spreads by both frog-to-frog and environment-to-frog transmission, and can persist on ...200717425258
additional disinfectants effective against the amphibian chytrid fungus batrachochytrium dendrobatidis.chytridiomycosis, a disease contributing to amphibian declines worldwide, is caused by the fungus batrachochytrium dendrobatidis. identifying efficient and practical disinfectants effective against b. dendrobatidis is important to reduce the spread of the disease both in the wild and captivity. previous studies identified a range of suitable disinfectant strategies. we evaluated the suitability of 3 additional disinfectants: two of these (trigene virucidal disinfectant cleaner and f10 super conc ...200717425259
ecology: global warming and amphibian losses.is global warming contributing to amphibian declines and extinctions by promoting outbreaks of the chytrid fungus batrachochytrium dendrobatidis? analysing patterns from the american tropics, pounds et al. envisage a process in which a single warm year triggers die-offs in a particular area (for instance, 1987 in the case of monteverde, costa rica). however, we show here that populations of two frog species in the australian tropics experienced increasing developmental instability, which is evid ...200717538571
amphibian chemical defense: antifungal metabolites of the microsymbiont janthinobacterium lividum on the salamander plethodon cinereus.disease has spurred declines in global amphibian populations. in particular, the fungal pathogen batrachochytrium dendrobatidis has decimated amphibian diversity in some areas unaffected by habitat loss. however, there is little evidence to explain how some amphibian species persist despite infection or even clear the pathogen beyond detection. one hypothesis is that certain bacterial symbionts on the skin of amphibians inhibit the growth of the pathogen. an antifungal strain of janthinobacteriu ...200818949519
distribution of frogs in rice bays within an irrigated agricultural area: links to pesticide usage and farm practices.in the coleambally irrigation area (nsw, australia), the occurrence of four tadpole and frog species in rice bays on farms growing either rice only or both rice and corn was studied over two seasons. in addition to analysis of species occurrence, both gonadal histology and assessment of batrachochytrium dendrobatidis infection rates were performed. the rice acreage available as potential tadpole habitat was extensively distributed throughout the irrigation area, but more corn was grown in the no ...200919220075
electrolyte depletion and osmotic imbalance in amphibians with chytridiomycosis.mounting evidence implicates the disease chytridiomycosis, caused by the fungus batrachochytrium dendrobatidis, in global amphibian declines and extinctions. while the virulence of this disease has been clearly demonstrated, there is, as yet, no mechanistic explanation for how b. dendrobatidis kills amphibians. to investigate the pathology of chytridiomycosis, blood samples were collected from uninfected, aclinically infected and clinically diseased amphibians and analyzed for a wide range of bi ...200717972752
a zoospore inhibition technique to evaluate the activity of antifungal compounds against batrachochytrium dendrobatidis and unsuccessful treatment of experimentally infected green tree frogs (litoria caerulea) by fluconazole and benzalkonium chloride.effective and safe treatments of chytridiomycosis in amphibians, caused by batrachochytrium dendrobatidis, are needed to help prevent mortality in captive programs for threatened species, to reduce the risk of spread, and to better manage the disease in threatened populations. we describe a simple method to determine minimum inhibitory concentrations (mics) of antifungal agents that involves adding zoospores to various drug concentrations in 96 well plates and microscopic observation after four ...200919117582
diversity of cutaneous bacteria with antifungal activity isolated from female four-toed salamanders.among the microbiota of amphibian skin are bacteria that produce antifungal compounds. we isolated cutaneous bacteria from the skins of three populations of the nest-attending plethodontid salamander hemidactylium scutatum and subsequently tested the bacterial isolates against two different fungi (related to mariannaea elegans and rhizomucor variabilis) that were obtained from dead salamander eggs. the culturable antifungal bacteria were phylogenetically characterized based on 16s rrna phylogeny ...200818079731
detection of batrachochytrium dendrobatidis in endemic salamander species from central texas.a nested pcr protocol was used to analyze five endemic salamander species from central texas for the presence of the emerging pathogen, chytrid fungus (batrachochytrium dendrobatidis). chytrid fungus was detected from samples of each of the five species sampled: with low abundance, in the texas salamander (eurycea neotenes) (1 positive out of 16 individuals tested; 1/16), the blanco river springs salamander (e. pterophila) (1/20), the threatened san marcos salamander (e. nana) (1/17), and the en ...200919424755
disease associated with integumentary and cloacal parasites in tadpoles of northern red-legged frog rana aurora aurora.a total of 6830 northern red-legged frog rana aurora aurora tadpoles were examined under a dissecting microscope for oral disc, integumentary, and cloacal abnormalities in 13 ponds in and near redwood national park in northern california. of these, 163 tadpoles were collected for histopathological investigation, including 115 randomly collected individuals, 38 collected with oral disc abnormalities, and 10 collected due to severe morbidity of unknown etiology. the tadpoles were infected with 8 p ...200718159674
survey for the amphibian chytrid batrachochytrium dendrobatidis in hong kong in native amphibians and in the international amphibian trade.chytridiomycosis, caused by the pathogen batrachochytrium dendrobatidis, is responsible for many amphibian declines and has been identified in wild amphibian populations on all continents where they exist, except for asia. in order to assess whether b. dendrobatidis is present on the native amphibians of hong kong, we sampled wild populations of amolops hongkongensis, paa exilispinosa, p. spinosa and rana chloronota during 2005-2006. amphibians infected with b. dendrobatidis have been found in t ...200718286805
survival of the amphibian chytrid fungus batrachochytrium dendrobatidis on bare hands and gloves: hygiene implications for amphibian handling.hygiene protocols for handling amphibians in the field and in laboratories have been proposed to decrease the transmission of chytridiomycosis caused by infection with the amphibian chytrid fungus batrachochytrium dendrobatidis, which is responsible for global amphibian declines. however, these protocols are mainly based on theoretical principles. the aim of this study was to develop an evidence-based approach to amphibian handling hygiene protocols by testing the survival of b. dendrobatidis on ...200819149372
chemotaxis of the amphibian pathogen batrachochytrium dendrobatidis and its response to a variety of attractants.batrachochytrium dendrobatidis is a fungal pathogen of amphibians that is increasingly implicated as a major cause of large-scale mortalities of amphibian species worldwide. previous studies indicate that motile zoospores of b. dendrobatidis colonize the keratinized tissues of susceptible amphibians. infections spread to adults and cause destruction of epidermal tissue. in an effort to understand how the chytrid cues into its host we developed an assay to study chemotaxis in the fungus. here we ...200818488347
immune defenses of xenopus laevis against batrachochytrium dendrobatidis.amphibian populations are declining at an unprecedented rate worldwide. a number of declines have been linked to a pathogenic skin fungus, batrachochytrium dendrobatidis. although amphibians have robust immune defenses, many species seem to be very susceptible to infection by this fungus and to development of the lethal disease called chytridiomycosis. one species that is relatively resistant to b. dendrobatidis is xenopus laevis. because x. laevis has been used as a model for studies of immunit ...200919482684
batrachochytrium dendrobatidis, a novel pathogen approaching endemism in central california.the recent emergence of amphibian chytridiomycosis has precipitated competing hypotheses regarding the endemic versus novel nature of the causative agent, batrachochytrium dendrobatidis (bd). we conducted a retrospective survey of the california academy of sciences' (san francisco, california, usa) amphibian collection, testing for presence of bd in 4 amphibian species collected from central california between 1897 and 2005. the earliest detection of bd was found in 2 rana catesbeiana in 1961, a ...200919301630
addition of antifungal skin bacteria to salamanders ameliorates the effects of chytridiomycosis.chytridiomycosis, caused by the skin fungus batrachochytrium dendrobatidis (bd), has caused population declines of many amphibians in remote protected habitats. progress has been made in understanding the pathogen's life cycle, documenting its devastating effects on individual amphibians and on populations, and understanding how and why disease outbreaks occur. no research has directly addressed the critical question of how to prevent declines and extinctions caused by outbreaks of the disease. ...200919301631
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