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Scientific Reports Sep 2020Two species of parasitic fungi from the phylum Chytridiomycota (chytrids) are annihilating global amphibian populations. These chytrid species-Batrachochytrium...
Two species of parasitic fungi from the phylum Chytridiomycota (chytrids) are annihilating global amphibian populations. These chytrid species-Batrachochytrium dendrobatidis and B. salamandrivorans-have high rates of mortality and transmission. Upon establishing infection in amphibians, chytrids rapidly multiply within the skin and disrupt their hosts' vital homeostasis mechanisms. Current disease models suggest that chytrid fungi locate and infect their hosts during a motile, unicellular 'zoospore' life stage. Moreover, other chytrid species parasitize organisms from across the tree of life, making future epidemics in new hosts a likely possibility. Efforts to mitigate the damage and spread of chytrid disease have been stymied by the lack of knowledge about basic chytrid biology and tools with which to test molecular hypotheses about disease mechanisms. To overcome this bottleneck, we have developed high-efficiency delivery of molecular payloads into chytrid zoospores using electroporation. Our electroporation protocols result in payload delivery to between 75 and 97% of living cells of three species: B. dendrobatidis, B. salamandrivorans, and a non-pathogenic relative, Spizellomyces punctatus. This method lays the foundation for molecular genetic tools needed to establish ecological mitigation strategies and answer broader questions in evolutionary and cell biology.
Topics: Amphibians; Animal Diseases; Animals; Chytridiomycota; Electroporation; Host-Pathogen Interactions; Mycoses; Spores, Fungal
PubMed: 32934254
DOI: 10.1038/s41598-020-71618-2 -
Comparative Biochemistry and... Mar 2021The globin gene repertoire of gnathostome vertebrates is dictated by differential retention and loss of nine paralogous genes: androglobin, neuroglobin, globin X,...
The globin gene repertoire of gnathostome vertebrates is dictated by differential retention and loss of nine paralogous genes: androglobin, neuroglobin, globin X, cytoglobin, globin Y, myoglobin, globin E, and the α- and β-globins. We report the globin gene repertoire of three orders of modern amphibians: Anura, Caudata, and Gymnophiona. Combining phylogenetic and conserved synteny analysis, we show that myoglobin and globin E were lost only in the Batrachia clade, but retained in Gymnophiona. The major amphibian groups also retained different paralogous copies of globin X. None of the amphibian presented α-globin gene. Nevertheless, two clades of β-globins are present in all amphibians, indicating that the amphibian ancestor possessed two paralogous proto β-globins. We also show that orthologs of the gene coding for the monomeric hemoglobin found in the heart of Rana catesbeiana are present in Neobatrachia and Pelobatoidea species we analyzed. We suggest that these genes might perform myoglobin- and globin E-related functions. We conclude that the repertoire of globin genes in amphibians is dictated by both retention and loss of the paralogous genes cited above and the rise of a new globin gene through co-option of an α-globin, possibly facilitated by a prior event of transposition.
Topics: Amphibians; Animals; Evolution, Molecular; Globins; Phylogeny; Synteny
PubMed: 33202310
DOI: 10.1016/j.cbd.2020.100759 -
Integrative and Comparative Biology Sep 2014Pathogens act as agents of evolutionary change in host populations, altering the host's allele frequencies and phenotypes through selection. The mechanisms underlying... (Review)
Review
Pathogens act as agents of evolutionary change in host populations, altering the host's allele frequencies and phenotypes through selection. The mechanisms underlying these adaptive changes depend on which defense strategy the host adopts upon infection. With increased anthropogenic change and loss of biodiversity, ecological impacts on adaptive processes may reduce the ability of hosts to evolve resistance, or to persist within their tolerance limits, thus increasing the capacity of pathogens to cause disease and mortality. In this review, we use amphibians and a pathogenic chytrid fungus (Batrachochytrium dendrobatidis, Bd) to illustrate how integrating genomic approaches into current research, both for hosts and pathogens, will improve our understanding of factors promoting the outcome of disease. As new emerging pathogens continue threatening amphibian populations worldwide, we recommend that researchers focus on individuals that survive after natural epizootics or experimental challenges. These survivors represent an underutilized and underexploited genetic resource for characterizing adaptive traits involved in the clearance of pathogens or in their tolerance. We highlight two target areas that will benefit from focused research: (1) Identification of the genetic basis of the hosts' defense strategies (resistance and tolerance) and of Bd's pathogenicity traits and (2) genomic characterization of shifts in fitness that drive seasonal and/or temporal patterns in host-pathogen interactions. To provide insights into hosts' survival, we review recent literature--including experimental Bd challenges and longitudinal studies--that underscore the complexity of Bd infections as determined by a combination of genetic and environmental factors. Given the heterogeneity of disease-outcomes and broad diversity of host species, amphibians provide a unique opportunity to identify novel genetic determinants of resistance to a recently emerged fungal pathogen. Developing additional genetic resources (e.g., genomic profiles, resistance mapping, and dual RNA-seq) will advance our understanding of the components of the innate and adaptive immune system acting on infected hosts in varying environments. These ecoimmunomic applications, which link host-pathogen eco-evolutionary processes with applied conservation efforts, will specifically benefit threatened amphibians that remain safeguarded in captive colonies.
Topics: Amphibians; Animals; Chytridiomycota; Genomics; Host-Pathogen Interactions; Mycoses
PubMed: 24916476
DOI: 10.1093/icb/icu073 -
Zootaxa Jun 2023North Sweden ('Norrland' in Swedish) covers 243 000 km2 and lies mainly in the boreal biome. The herpetofauna comprises five amphibian and four reptile species:...
North Sweden ('Norrland' in Swedish) covers 243 000 km2 and lies mainly in the boreal biome. The herpetofauna comprises five amphibian and four reptile species: Lissotriton vulgaris, Triturus cristatus, Bufo bufo, Rana temporaria, Rana arvalis, Zootoca vivipara, Anguis fragilis, Natrix natrix, and Vipera berus. Successful conservation and management of amphibians and reptiles depend on accurate information about distribution, habitat affinities, and abundance. Such knowledge is also essential as a benchmark to assess changes in distribution and abundance that may come about as a result of climate change and human habitat alteration. This paper aims to present accurate distribution maps, describe habitat affinities, and provide abundance estimates for the herpetofauna of North Sweden for the period 1970-2022. Distribution data are presented by traditional faunistic provinces, as well as by biotic regions and alpine life zones. Separate sections address post-glacial colonization and a herpetological perspective on anthropogenic changes in relation to species´ present status. Bufo bufo, Rana temporaria, Rana arvalis, Zootoca vivipara, and Vipera berus are widely distributed throughout the boreal sub-regions. Rana temporaria, Zootoca vivipara, and Vipera berus also extend into the alpine region. Triturus cristatus, Anguis fragilis, and Natrix natrix occur mainly in the coastal parts of the Southern Boreal region. There are no signs of recent changes in distribution range, but Lissotriton vulgaris, Triturus cristatus, and Rana arvalis have been largely overlooked in the past and have a much wider occurrence than previously recognized. Most species are found in habitats usually not described in all-European field guides. Nearly all anurans hibernate in water. Abundance estimates suggest that some species are more common in the boreal than thought, supporting the notion that a large share of their total European population occurs there. Although local extinctions and declines are known, there are no signs of widespread population decline for any species during the study period.
Topics: Humans; Animals; Sweden; Amphibians; Reptiles; Ecosystem; Anura; Ranidae; Viperidae; Colubridae; Lizards
PubMed: 37518558
DOI: 10.11646/zootaxa.5301.3.1 -
Developmental Neurobiology May 2019Regeneration of lost cells in the central nervous system, especially the brain, is present to varying degrees in different species. In mammals, neuronal cell death often... (Comparative Study)
Comparative Study Review
Regeneration of lost cells in the central nervous system, especially the brain, is present to varying degrees in different species. In mammals, neuronal cell death often leads to glial cell hypertrophy, restricted proliferation, and formation of a gliotic scar, which prevents neuronal regeneration. Conversely, amphibians such as frogs and salamanders and teleost fish possess the astonishing capacity to regenerate lost cells in several regions of their brains. While frogs lose their regenerative abilities after metamorphosis, teleost fish and salamanders are known to possess regenerative competence even throughout adulthood. In the last decades, substantial progress has been made in our understanding of the cellular and molecular mechanisms of brain regeneration in amphibians and fish. But how similar are the means of brain regeneration in these different species? In this review, we provide an overview of common and distinct aspects of brain regeneration in frog, salamander, and teleost fish species: from the origin of regenerated cells to the functional recovery of behaviors.
Topics: Amphibians; Animals; Brain; Brain Injuries; Fishes; Metamorphosis, Biological; Nerve Regeneration; Species Specificity
PubMed: 30600647
DOI: 10.1002/dneu.22665 -
EcoHealth Dec 2017Amphibians are experiencing devastating population declines globally. A major driver is chytridiomycosis, an emerging infectious disease caused by the fungal pathogens... (Review)
Review
Amphibians are experiencing devastating population declines globally. A major driver is chytridiomycosis, an emerging infectious disease caused by the fungal pathogens Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal). Bd was described in 1999 and has been linked with declines since the 1970s, while Bsal is a more recently discovered pathogen that was described in 2013. It is hypothesized that Bsal originated in Asia and spread via international trade to Europe, where it has been linked to salamander die-offs. Trade in live amphibians thus represents a significant threat to global biodiversity in amphibians. We review the current state of knowledge regarding Bsal and describe the risk of Bsal spread. We discuss regional responses to Bsal and barriers that impede a rapid, coordinated global effort. The discovery of a second deadly emerging chytrid fungal pathogen in amphibians poses an opportunity for scientists, conservationists, and governments to improve global biosecurity and further protect humans and wildlife from a growing number of emerging infectious diseases.
Topics: Amphibians; Animals; Animals, Wild; Chytridiomycota; Communicable Diseases, Emerging; Mycoses; Pandemics
PubMed: 29147975
DOI: 10.1007/s10393-017-1278-1 -
Biotechnology and Bioengineering Feb 2024In recent years, environmental DNA (eDNA) has received attention from biologists due to its sensitivity, convenience, labor and material efficiency, and lack of damage... (Review)
Review
In recent years, environmental DNA (eDNA) has received attention from biologists due to its sensitivity, convenience, labor and material efficiency, and lack of damage to organisms. The extensive application of eDNA has opened avenues for the monitoring and biodiversity assessment of amphibians, which are frequently small and difficult to observe in the field, in areas such as biodiversity survey assessment and detection of specific, rare and threatened, or alien invasive species. However, the accuracy of eDNA can be influenced by factors such as ambient temperature, pH, and false positives or false negatives, which makes eDNA an adjunctive tool rather than a replacement for traditional surveys. This review provides a concise overview of the eDNA method and its workflow, summarizes the differences between applying eDNA for detecting amphibians and other organisms, reviews the research progress in eDNA technology for amphibian monitoring, identifies factors influencing detection efficiency, and discusses the challenges and prospects of eDNA. It aims to serve as a reference for future research on the application of eDNA in amphibian detection.
Topics: Animals; DNA, Environmental; Ecosystem; Amphibians; Biodiversity
PubMed: 37986625
DOI: 10.1002/bit.28592 -
The Science of the Total Environment Oct 2019Nanomaterials (NMs) have been used in a growing number of commercial products, and their rapid expansion could lead to their release into the aquatic environments.... (Review)
Review
Nanomaterials (NMs) have been used in a growing number of commercial products, and their rapid expansion could lead to their release into the aquatic environments. However, there is limited knowledge about the impact of NMs in the biota, especially the amphibians. The present study revised the historical use of amphibian species as a model system for nanoecotoxicological studies and summarized the data available in the scientific literature about the genotoxic, mutagenic, histopathological, embryotoxic and reproductive effects of NMs in different groups of amphibians. The interaction, bioaccumulation, mode of action (MoA) and ecotoxicity of NMs on amphibians were also revised. The nanoecotoxicological studies were conducted with 11 amphibian species, being eight species of the order Anura and three species of the order Caudata. Xenopus laevis was the most studied species. The studies were conducted mainly with inorganic NMs (72%) compared to organic ones. The nanoecotoxicity depends on NM behavior and transformation in the environment, as well as the developmental stages of amphibians. The known effects of NMs in amphibians were mainly reported with reactive oxygen species (ROS) production, oxidative stress, and genotoxic effects. Results emphasize the need for further studies testing the ecotoxicity of different NMs, concentrations and exposure periods at environmentally relevant approaches. Furthermore, standard protocols for nanoecotoxicological tests using amphibians are required. Revised data showed that amphibians are suitable organisms to assess the environmental impact of NMs and indicated significant research gaps concerning the ecotoxicity of NMs on freshwater ecosystems and recommendations for future researches.
Topics: Amphibians; Animals; Biota; Mutagens; Nanostructures; Oxidative Stress; Water Pollutants, Chemical
PubMed: 31181520
DOI: 10.1016/j.scitotenv.2019.05.487 -
Journal of Experimental Zoology. Part... Apr 2022Quantifying ectotherm body temperature is important to understand physiological performance under environmental change. The increasing availability of small,...
Quantifying ectotherm body temperature is important to understand physiological performance under environmental change. The increasing availability of small, commercially-available animal-borne biologgers increases accessibility to high-quality body temperature data. However, amphibians present several challenges to successful datalogger implantation including small body sizes and physiologically active skin. We developed a method for the implantation, extraction, and validation of temperature biologgers in captive salamanders. We assessed the effect of biologger implantation and extraction surgery on body condition. Implantation had no effects on short or long-term body condition. Body condition also did not differ between implant and control groups after datalogger extraction. Biologgers did not alter preferred temperature in a laboratory thermal gradient, indicating that temperature data would not be biased by implantation. We provide detailed recommendations for datalogger placement and refinement of surgical techniques to further improve outcomes, enhance our understanding of fitness, species range limitations, and responses to environmental and climatic change.
Topics: Amphibians; Animals; Body Temperature; Climate Change; Temperature; Urodela
PubMed: 34982510
DOI: 10.1002/jez.2575 -
Veterinary Research Nov 2015Amphibian declines and extinctions are emblematic for the current sixth mass extinction event. Infectious drivers of these declines include the recently emerged fungal... (Review)
Review
Amphibian declines and extinctions are emblematic for the current sixth mass extinction event. Infectious drivers of these declines include the recently emerged fungal pathogens Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans (Chytridiomycota). The skin disease caused by these fungi is named chytridiomycosis and affects the vital function of amphibian skin. Not all amphibians respond equally to infection and host responses might range from resistant, over tolerant to susceptible. The clinical outcome of infection is highly dependent on the amphibian host, the fungal virulence and environmental determinants. B. dendrobatidis infects the skin of a large range of anurans, urodeles and caecilians, whereas to date the host range of B. salamandrivorans seems limited to urodeles. So far, the epidemic of B. dendrobatidis is mainly limited to Australian, neotropical, South European and West American amphibians, while for B. salamandrivorans it is limited to European salamanders. Other striking differences between both fungi include gross pathology and thermal preferences. With this review we aim to provide the reader with a state-of-the art of host-pathogen interactions for both fungi, in which new data pertaining to the interaction of B. dendrobatidis and B. salamandrivorans with the host's skin are integrated. Furthermore, we pinpoint areas in which more detailed studies are necessary or which have not received the attention they merit.
Topics: Amphibians; Animals; Chytridiomycota; Dermatomycoses; Host-Pathogen Interactions; Species Specificity; Virulence
PubMed: 26607488
DOI: 10.1186/s13567-015-0266-0