scholarly journals Development and worldwide use of a non-lethal and minimal population-level impact protocols for the isolation of chytrids from amphibians

2018 ◽  
Author(s):  
Matthew C. Fisher ◽  
Pria Ghosh ◽  
Jennifer M. G. Shelton ◽  
Kieran Bates ◽  
Lola Brookes ◽  
...  
Keyword(s):  
Fungal Pathogens ◽  
Batrachochytrium Dendrobatidis ◽  
Population Level ◽  
Ability To Work ◽  
Amphibian Species ◽  
Sterile Culture ◽  
Important Group ◽  
Fungal Isolates ◽  
Emerging Fungal Pathogens

ABSTRACTParasitic chytrid fungi have emerged as a significant threat to amphibian species worldwide, necessitating the development of techniques to isolate these pathogens into sterile culture for research purposes. However, early methods of isolating chytrids from their hosts relied on killing amphibians. We modified a pre-existing protocol for isolating chytrids from infected animals to use toe clips and biopsies from toe webbing rather than euthanizing hosts, and distributed the protocol to interested researchers worldwide as part of the BiodivERsA project RACE – here called the RML protocol. In tandem, we developed a lethal procedure for isolating chytrids from tadpole mouthparts. Reviewing a database of use a decade after their inception, we find that these methods have been widely applied across at least 5 continents, 23 countries and in 62 amphibian species, and have been successfully used to isolate chytrids in remote field locations. Isolation of chytrids by the non-lethal RML protocol occured in 18% of attempts with 207 fungal isolates and three species of chytrid being recovered. Isolation of chytrids from tadpoles occured in 43% of attempts with 334 fungal isolates of one species (Batrachochytrium dendrobatidis) being recovered. Together, these methods have resulted in a significant reduction and refinement of our use of threatened amphibian species and have improved our ability to work with this important group of emerging fungal pathogens.

scholarly journals Epidermal galactose spurs chytrid virulence and predicts amphibian colonization

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yu Wang ◽  
Elin Verbrugghe ◽  
Leander Meuris ◽  
Koen Chiers ◽  
Moira Kelly ◽  
...  
Keyword(s):  
Disease Ecology ◽  
Fungal Pathogens ◽  
Batrachochytrium Dendrobatidis ◽  
Host Susceptibility ◽  
Fungal Colonization ◽  
Amphibian Skin ◽  
Glycosylation Pattern ◽  
Amphibian Species ◽  
Juvenile Mortality ◽  
Galactose Content

AbstractThe chytrid fungal pathogens Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans cause the skin disease chytridiomycosis in amphibians, which is driving a substantial proportion of an entire vertebrate class to extinction. Mitigation of its impact is largely unsuccessful and requires a thorough understanding of the mechanisms underpinning the disease ecology. By identifying skin factors that mediate key events during the early interaction with B. salamandrivorans zoospores, we discovered a marker for host colonization. Amphibian skin associated beta-galactose mediated fungal chemotaxis and adhesion to the skin and initiated a virulent fungal response. Fungal colonization correlated with the skin glycosylation pattern, with cutaneous galactose content effectively predicting variation in host susceptibility to fungal colonization between amphibian species. Ontogenetic galactose patterns correlated with low level and asymptomatic infections in salamander larvae that were carried over through metamorphosis, resulting in juvenile mortality. Pronounced variation of galactose content within some, but not all species, may promote the selection for more colonization resistant host lineages, opening new avenues for disease mitigation.

scholarly journals Fungal infection, decline and persistence in the only obligate troglodytic Neotropical salamander

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9763
Author(s):  
Mizraim Olivares-Miranda ◽  
Vance T. Vredenburg ◽  
Julio C. García-Sánchez ◽  
Allison Q. Byrne ◽  
Erica B. Rosenblum ◽  
...  
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
Infection Intensity ◽  
Sampling Technique ◽  
Sympatric Species ◽  
Amphibian Declines ◽  
Small Range ◽  
Museum Specimens ◽  
Amphibian Species ◽  
Extant Population ◽  
Epidemic Wave

The fungal pathogen Batrachochytrium dendrobatidis (Bd) is implicated in global mass die-offs and declines in amphibians. In Mesoamerica, the Bd epidemic wave hypothesis is supported by detection of Bd in historic museum specimens collected over the last century, yet the timing and impact of the early stages of the wave remain poorly understood. Chiropterotriton magnipes, the only obligate troglodytic Neotropical salamander, was abundant in its small range in the decade following its description in 1965, but subsequently disappeared from known localities and was not seen for 34 years. Its decline is roughly coincident with that of other populations of Neotropical salamanders associated with the invasion and spread of Bd. To determine the presence and infection intensity of Bd on C. magnipes and sympatric amphibian species (which are also Bd hosts), we used a noninvasive sampling technique and qPCR assay to detect Bd on museum specimens of C. magnipes collected from 1952 to 2012, and from extant populations of C. magnipes and sympatric species of amphibians. We also tested for the presence of the recently discovered Batrachochytrium salamandivorans (Bsal), another fungal chytridiomycete pathogen of salamanders, using a similar technique specific for Bsal. We did not detect Bd in populations of C. magnipes before 1969, while Bd was detected at low to moderate prevalence just prior to and during declines. This pattern is consistent with Bd-caused epizootics followed by host declines and extirpations described in other hosts. We did not detect Bsal in any extant population of C. magnipes. We obtained one of the earliest positive records of the fungus to date in Latin America, providing additional historical evidence consistent with the Bd epidemic wave hypothesis. Genotyping results show that at least one population is currently infected with the Global Panzootic Lineage of Bd, but our genotyping of the historical positive samples was unsuccessful. The lack of large samples from some years and the difficulty in genotyping historical Bd samples illustrate some of the difficulties inherent in assigning causality to historical amphibian declines. These data also provide an important historical baseline for actions to preserve the few known remaining populations of C. magnipes.

scholarly journals Establishement of a national monitoring program based on environmental DNA for amphibians and the chytrid fungus Batrachochytrium dendrobatidis     

2021 ◽  
Vol 4 ◽  
Author(s):  
Omneya Osman ◽  
Johan Andersson ◽  
Tomas Larsson ◽  
Mats Töpel ◽  
Alexander Eiler
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
National Level ◽  
Monitoring Program ◽  
12S Rrna ◽  
Rrna Gene ◽  
Chytrid Fungus ◽  
Rana Arvalis ◽  
Amphibian Species ◽  
National Monitoring ◽  
Wide Range

National monitoring programs provide the basis for evaluating the integrity of ecosystems, their responses to disturbances, and the success of actions taken to conserve or recover biodiversity. In this study, we successfully established a national program for the invasive chytrid fungus Batrachochytrium dendrobatidis (Bd) based on dual TaqMan assays. Amphibian diversity based on metabarcoding of the mitochondrial 12S rRNA gene was also performed. Assays were optimized for sensitive detection of target species from a wide range of amphibian ponds with variable potential of inhibitions for eDNA based detection. An amphibian mock community of 5 species was used to validate the metabarcoding approach while internal standards were used in the case of the dual TaqMan assays. First sampling of over 170 ponds in Norway resulted in Bd detection in 12 environmental samples and one swab sample taken over multiple years indicating the establishment of Bd in Norway. Five amphibian species Bufo bufo, Lissotriton vulgaris, Triturus cristatus, Rana arvalis and Rana temporaria as predicted from data in long-term citizen science reporting systems were widely detected in the collected eDNA samples. Our large scale-monitoring program indicates a low risk of a Bd outbreak and amphibian decline caused by chytridiomycosis but continued monitoring is recommended in the future. These findings indicate that eDNA is an effective method to detect invasive species, and to monitor endangered amphibian species. Still, several shortcomings (such as PCR inhibitors and sample volume) were identified that need to be addressed to improve eDNA-based monitoring at the national level.

scholarly journals Habitat fragmentation in the Brazilian Atlantic Forest is associated with erosion of frog immunogenetic diversity and increased fungal infections

2021 ◽  
Author(s):  
Anat Belasen ◽  
Kevin Amses ◽  
Rebecca Clemons ◽  
Guilherme Becker ◽  
Felipe Toledo ◽  
...  
Keyword(s):  
Habitat Fragmentation ◽  
Atlantic Forest ◽  
Batrachochytrium Dendrobatidis ◽  
Fungal Infections ◽  
Emerging Infectious Diseases ◽  
Genetic Erosion ◽  
Population Level ◽  
Brazilian Atlantic Forest ◽  
Frog Species ◽  
Mhc Iib

Habitat fragmentation and infectious disease threaten amphibians globally, but little is known about how these two threats interact. In this study, we examined the effects of Brazilian Atlantic Forest habitat fragmentation on frog genetic diversity at an immune locus known to affect disease susceptibility in amphibians, the MHC IIB locus. We used a custom high-throughput assay to sequence the MHC IIB locus across six focal frog species in two regions of the Atlantic Forest. We also used a molecular assay to quantify infections by the fungal pathogen Batrachochytrium dendrobatidis (Bd). We found that habitat fragmentation is associated with genetic erosion at the MHC IIB locus, and that this erosion is most severe in frog species restricted to intact forests. Significant Bd infections were recovered only in one Atlantic Forest region, potentially due to the relatively higher elevation. In this region, forest specialists showed an increase in both Bd prevalence and loads in fragmented habitats. We also found that reduced population-level MHC IIB diversity was associated with increased Bd infection risk. On the individual-level, MHC IIB heterozygotes (by allelic genotype as well as supertype) exhibited a reduced risk of Bd infection. Our results suggest that habitat fragmentation increases infection susceptibility in amphibians, mediated at least in part through loss of immunogenetic diversity. Our findings have implications for the conservation of fragmented populations in the face of emerging infectious diseases.

Isolation and Identification of Fungal Isolates caused Otomycosis from some Hospitals and Clinics in Mosul with Determination of Their Virulence Factors

2021 ◽  
Vol 26 (4) ◽  
Author(s):  
Nabeel Al-Sharrad ◽  
Muhammad A. Al-Kataan ◽  
Maha A. Al-Rejaboo
Keyword(s):  
Fungal Infection ◽  
Virulence Factors ◽  
Biofilm Formation ◽  
Fungal Pathogens ◽  
Candida Parapsilosis ◽  
Isolation And Identification ◽  
Fungal Isolates ◽  
Biofilm Production ◽  
Etiological Agents

Otomycosis is a fungal infection that frequently involves the external auditory canal. In this study, we aimed to isolation and identification the fungal isolates as etiological agents of otomycosis from some hospitals and clinics in Mosul with determination of their virulence factors of fungal etiological agents. Positive fungal infection was found in (43) samples (71.6%). The most common fungal pathogens were Candida and Aspergillus species, with Candida parapsilosis being the predominant isolates in (11) samples (16.6%). Otomycosis was more common in Female in (26) samples (43.3%).Otomycosis was the highest prevalence aged group 15-40 years (19) samples (31.3%). The present study of virulence factors revealed that the highest biofilm formation isolates were C. parapsilosis is (10) isolates which were distributed between (2) strong and (8) weak biofilm formation.Where C.trpicales, was recorded as least isolates for biofilm production.

scholarly journals Ancestral chytrid pathogen remains hypervirulent following its long coevolution with amphibian hosts

2019 ◽  
Vol 286 (1904) ◽  
pp. 20190833 ◽  
Author(s):  
Minjie Fu ◽  
Bruce Waldman
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
Population Declines ◽  
Amphibian Species ◽  
South Korean ◽  
Global Pandemic ◽  
Litoria Caerulea ◽  
Experimental Treatments ◽  
Amphibian Chytrid Fungus ◽  
Genomic Recombination ◽  
Blank Solution

Many amphibian species around the world, except in Asia, suffer morbidity and mortality when infected by the emerging infectious pathogen Batrachochytrium dendrobatidis (Bd). A lineage of the amphibian chytrid fungus isolated from South Korean amphibians (BdAsia-1) is evolutionarily basal to recombinant global pandemic lineages (BdGPL) associated with worldwide amphibian population declines. In Asia, the Bd pathogen and its amphibian hosts have coevolved over 100 years or more. Thus, resilience of Asian amphibian populations to infection might result from attenuated virulence of endemic Bd lineages, evolved immunity to the pathogen or both. We compared susceptibilities of an Australasian amphibian, Litoria caerulea , known to lack resistance to BdGPL, with those of three Korean species, Bufo gargarizans , Bombina orientalis and Hyla japonica , after inoculation with BdAsia-1, BdGPL or a blank solution. Subjects became infected in all experimental treatments but Korean species rapidly cleared themselves of infection, regardless of Bd lineage. They survived with no apparent secondary effects. By contrast, L. caerulea , after infection by either BdAsia-1 or BdGPL, suffered deteriorating body condition and carried progressively higher Bd loads over time. Subsequently, most subjects died. Comparing their effects on L. caerulea , BdAsia-1 induced more rapid disease progression than BdGPL. The results suggest that genomic recombination with other lineages was not necessary for the ancestral Bd lineage to evolve hypervirulence over its long period of coevolution with amphibian hosts. The pathogen's virulence may have driven strong selection for immune responses in endemic Asian amphibian host species.

scholarly journals Tracking Batrachochytrium dendrobatidis Infection Across the Globe

EcoHealth ◽  
2020 ◽  
Vol 17 (3) ◽  
pp. 270-279
Author(s):  
Federico Castro Monzon ◽  
Mark-Oliver Rödel ◽  
Jonathan M. Jeschke
Keyword(s):  
Systematic Review ◽  
Host Species ◽  
Batrachochytrium Dendrobatidis ◽  
Atlantic Coast ◽  
Amphibian Species ◽  
Species Overlap ◽  
The Usa

AbstractInfection records of Batrachochytrium dendrobatidis (Bd), a pathogen that has devastated amphibian populations worldwide, have rapidly increased since the pathogen’s discovery. Dealing with so many records makes it difficult to (a) know where, when and in which species infections have been detected, (b) understand how widespread and pervasive Bd is and (c) prioritize study and management areas. We conducted a systematic review of papers and compiled a database with Bd infection records. Our dataset covers 71 amphibian families and 119 countries. The data revealed how widespread and adaptable Bd is, being able to infect over 50% of all tested amphibian species, with over 1000 confirmed host species and being present in 86 countries. The distribution of infected species is uneven among and within countries. Areas where the distributions of many infected species overlap are readily visible; these are regions where Bd likely develops well. Conversely, areas where the distributions of species that tested negative overlap, such as the Atlantic Coast in the USA, suggest the presence of Bd refuges. Finally, we report how the number of tested and infected species has changed through time, and provide a list of oldest detection records per country.

scholarly journals Phylogenetic investigation of skin sloughing rates in frogs: relationships with skin characteristics and disease-driven declines

2019 ◽  
Vol 286 (1896) ◽  
pp. 20182378 ◽  
Author(s):  
Michel E. B. Ohmer ◽  
Rebecca L. Cramp ◽  
Craig R. White ◽  
Peter S. Harlow ◽  
Michael S. McFadden ◽  
...  
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
Phylogenetic Signal ◽  
Interspecific Variation ◽  
Phylogenetic Position ◽  
Turnover Rates ◽  
Amphibian Skin ◽  
Amphibian Species ◽  
Wide Range ◽  
Skin Morphology ◽  
And Function

Amphibian skin is highly variable in structure and function across anurans, and plays an important role in physiological homeostasis and immune defence. For example, skin sloughing has been shown to reduce pathogen loads on the skin, such as the lethal fungus Batrachochytrium dendrobatidis ( Bd ), but interspecific variation in sloughing frequency is largely unknown. Using phylogenetic linear mixed models, we assessed the relationship between skin turnover rate, skin morphology, ecological traits and overall evidence of Bd -driven declines. We examined skin sloughing rates in 21 frog species from three continents, as well as structural skin characteristics measured from preserved specimens. We found that sloughing rate varies significantly with phylogenetic group, but was not associated with evidence of Bd -driven declines, or other skin characteristics examined. This is the first comparison of sloughing rate across a wide range of amphibian species, and creates the first database of amphibian sloughing behaviour. Given the strong phylogenetic signal observed in sloughing rate, approximate sloughing rates of related species may be predicted based on phylogenetic position. While not related to available evidence of declines, understanding variation in sloughing rate may help explain differences in the severity of infection in genera with relatively slow skin turnover rates (e.g. Atelopus ).

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