The Experts below are selected from a list of 735 Experts worldwide ranked by ideXlab platform
Franklin, Craig E. - One of the best experts on this subject based on the ideXlab platform.
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Mechanistic basis for the loss of water balance in green tree frogs infected with a fungal pathogen
'American Physiological Society', 2019Co-Authors: Wu, Nicholas C., Cramp, Rebecca L., Mckercher Callum, Franklin, Craig E.Abstract:Chytridiomycosis, a lethal Skin disease caused by the fungal pathogen () disrupts Skin function of amphibians, interfering with ionic and osmotic regulation. To regulate fungal loads, amphibians increase their rate of Skin Sloughing. However, Sloughing also causes a temporary loss of ionic and osmotic homeostasis due to disruption of the Skin, a key osmoregulatory organ. The combined effects of increased Sloughing frequency and chytridiomycosis contribute to the high rates of mortality from infections. However, the mechanisms responsible for the loss of cutaneous osmotic regulation remain unknown. We measured the changes in whole-animal water uptake rates, trans-cutaneous water fluxes across the ventral Skin, and the mRNA expression of epithelial water transport proteins (aquaporins, AQPs) and junctional proteins in -infected and uninfected Skin. We hypothesize that infected frogs would show reduction/inhibition in cutaneous water transporters responsible for regulating water balance, and Sloughing would exacerbate cutaneous water fluxes. We found that infected, non-Sloughing frogs had an impaired rate of water uptake and showed increased rates of water efflux across the ventral Skin. In uninfected frogs, the expression of AQPs and junction genes increased significantly with Sloughing which may assist in regulating cutaneous water movements and barrier function in the newly exposed Skin. In contrast, infected frogs did not show this post-Sloughing increase in AQP gene expression. The combination of increased Sloughing frequency, impaired water uptake rates and increased rates of water loss likely contributes to the loss of osmotic homeostasis in frogs infected with
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Phylogenetic investigation of Skin Sloughing rates in frogs: relationships with Skin characteristics and disease-driven declines
'The Royal Society', 2019Co-Authors: Ohmer, Michel E. B., Cramp, Rebecca L., White, Craig R., Harlow, Peter S., Mcfadden, Michael S., Merino-viteri Andrés, Pessier, Allan P., Wu, Nicholas C., Bishop, Phillip J., Franklin, Craig E.Abstract: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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Data from: Skin Sloughing in susceptible and resistant amphibians regulates infection with a fungal pathogen
2017Co-Authors: Ohmer, Michel E. B., Cramp, Rebecca L., Russo, Catherine J. M., White, Craig R., Franklin, Craig E.Abstract:The fungal pathogen Batrachochytrium dendrobatidis (Bd) has been implicated in amphibian population declines globally. Given that Bd infection is limited to the Skin in post-metamorphic amphibians, routine Skin Sloughing may regulate infection. Skin Sloughing has been shown to reduce the number of cultivatable microbes on amphibian Skin, and Bd infection increases Skin Sloughing rates at high loads. However, it is unclear whether species specific differences in Skin Sloughing patterns could regulate Bd population growth on the Skin, and influence subsequent infection dynamics. We exposed five Australian frog species to Bd, and monitored Sloughing rates and infection loads over time. Sloughing reduced Bd load on the ventral Skin surface, in all five species, despite wide variation in susceptibility to disease. In the least susceptible species, an increase in Sloughing rate occurred at lower infection loads, and Sloughing reduced Bd load up to 100%, leading to infection clearance. Conversely, the drop in Bd load with Sloughing was only temporary in the more susceptible species. These findings indicate that the ability of Sloughing to act as an effective immune defence is species specific, and they have implications for understanding the pattern of Bd population growth on individual hosts, as well as population-level effects
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Data from: Skin Sloughing rate increases with chytrid fungus infection load in a susceptible amphibian
2014Co-Authors: Ohmer, Michel E. B., Cramp, Rebecca L., White, Craig R., Franklin, Craig E.Abstract:1. Amphibian chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is responsible for the greatest disease-driven loss of vertebrate biodiversity in recorded history. Understanding drivers of host susceptibility to this cutaneous disease is hindered by gaps in our knowledge of the host–pathogen relationship. One such overlooked aspect of susceptibility is variation in Skin maintenance processes, particularly Skin turnover via routine Sloughing. It has been suggested that Sloughing plays a role in immune defence, by removing Skin-associated microbes. Thus, Skin Sloughing may play an important role in the pathogenesis of chytridiomycosis. 2. To determine the relationship between Skin Sloughing and disease progression, we exposed adult Australian green tree frogs (Litoria caerulea) to a local Bd strain and monitored Sloughing rates and individual infection loads on a naturalistic cycling temperature regime (15–23 °C). 3. We determined Sloughing rates in real-time by using an array of infrared video cameras to film frog behaviour and monitored infection load before and after Sloughing by swabbing and analysis with quantitative PCR. 4. We found that Sloughing rate increased with Bd infection load in infected frogs, but Sloughing itself did not affect Bd load on the ventral Skin surface. Furthermore, Bd infection did not affect the duration of characteristic Sloughing behaviour, and Sloughing retained rhythmicity even at high infection loads. 5. Although an increased Sloughing rate might be considered advantageous for Bd-infected animals, it does not appear to curb the progression of disease and may actually contribute to the loss of physiological homoeostasis seen in terminally ill frogs by further inhibiting water and electrolyte transport across the Skin. 6. By measuring Sloughing rates directly for the first time, our results shed light on how Bd interacts with the physiological processes of the Skin and indicate that variation in Skin Sloughing frequency may play a role in the observed inter- and intraspecific variation in susceptibility to disease
Craig E. Franklin - One of the best experts on this subject based on the ideXlab platform.
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Phylogenetic investigation of Skin Sloughing rates in frogs: relationships with Skin characteristics and disease-driven declines
Proceedings of the Royal Society B: Biological Sciences, 2019Co-Authors: Michel E. B. Ohmer, Rebecca L. Cramp, Craig R. White, Peter S. Harlow, Michael Mcfadden, Andrés Merino-viteri, Allan P. Pessier, Phillip J. Bishop, Craig E. FranklinAbstract: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 t...
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A pathogenic Skin fungus and Sloughing exacerbate cutaneous water loss in amphibians
The Journal of Experimental Biology, 2018Co-Authors: Catherine J. M. Russo, Michel E. B. Ohmer, Rebecca L. Cramp, Craig E. FranklinAbstract:Abstract Batrachochytrium dendrobatidis ( Bd ) is a pathogenic fungus that causes the cutaneous, infectious disease chytridiomycosis and has been implicated in population declines of numerous anuran species worldwide. Proximate cause of death by chytridiomycosis is asystolic cardiac arrest as a consequence of severe disruption to electrolyte balance. Animals heavily infected with Bd also experience a disruption to their Skin Sloughing regime, indicating that core functions of the Skin, such as water retention, may be severely impacted. This study examined how Skin Sloughing, body size and Bd infection interact to influence water loss rates in five Australian frog species: Litoria caerulea , Limnodynastes peronii , Lechriodus fletcheri , Limnodynastes tasmaniensis and Platyplectrum ornatum . Rates of water loss more than doubled during Sloughing in L . caerulea . During active periods across all species, water loss rates were on average 232% higher in Bd infected frogs than in uninfected frogs. This indicates that dehydration stress may be a significant factor contributing to the morbidity of severely Bd infected anurans, a symptom that is then exacerbated by an increased rate of Sloughing. When taking size into account, smaller and/or juvenile anurans may be more at risk from dehydration due to Bd infection, as they lose a greater amount of water and slough more frequently than adults. This may in part explain the higher mortality rates typical for small and juvenile frogs infected with Bd . Understanding how Bd affects the core functions of the Skin, including rates of water loss, can improve our predictions of disease outcome in amphibians.
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Skin Sloughing in susceptible and resistant amphibians regulates infection with a fungal pathogen.
Scientific Reports, 2017Co-Authors: Michel E. B. Ohmer, Rebecca L. Cramp, Catherine J. M. Russo, Craig R. White, Craig E. FranklinAbstract:The fungal pathogen Batrachochytrium dendrobatidis (Bd) has been implicated in amphibian population declines globally. Given that Bd infection is limited to the Skin in post-metamorphic amphibians, routine Skin Sloughing may regulate infection. Skin Sloughing has been shown to reduce the number of cultivatable microbes on amphibian Skin, and Bd infection increases Skin Sloughing rates at high loads. However, it is unclear whether species specific differences in Skin Sloughing patterns could regulate Bd population growth on the Skin, and influence subsequent infection dynamics. We exposed five Australian frog species to Bd, and monitored Sloughing rates and infection loads over time. Sloughing reduced Bd load on the ventral Skin surface, in all five species, despite wide variation in susceptibility to disease. In the least susceptible species, an increase in Sloughing rate occurred at lower infection loads, and Sloughing reduced Bd load up to 100%, leading to infection clearance. Conversely, the drop in Bd load with Sloughing was only temporary in the more susceptible species. These findings indicate that the ability of Sloughing to act as an effective immune defence is species specific, and they have implications for understanding the pattern of Bd population growth on individual hosts, as well as population-level effects.
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Skin Sloughing rate increases with chytrid fungus infection load in a susceptible amphibian
Functional Ecology, 2014Co-Authors: Michel E. B. Ohmer, Rebecca L. Cramp, Craig R. White, Craig E. FranklinAbstract:Summary Amphibian chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is responsible for the greatest disease-driven loss of vertebrate biodiversity in recorded history. Understanding drivers of host susceptibility to this cutaneous disease is hindered by gaps in our knowledge of the host–pathogen relationship. One such overlooked aspect of susceptibility is variation in Skin maintenance processes, particularly Skin turnover via routine Sloughing. It has been suggested that Sloughing plays a role in immune defence, by removing Skin-associated microbes. Thus, Skin Sloughing may play an important role in the pathogenesis of chytridiomycosis. To determine the relationship between Skin Sloughing and disease progression, we exposed adult Australian green tree frogs (Litoria caerulea) to a local Bd strain and monitored Sloughing rates and individual infection loads on a naturalistic cycling temperature regime (15–23 °C). We determined Sloughing rates in real-time by using an array of infrared video cameras to film frog behaviour and monitored infection load before and after Sloughing by swabbing and analysis with quantitative PCR. We found that Sloughing rate increased with Bd infection load in infected frogs, but Sloughing itself did not affect Bd load on the ventral Skin surface. Furthermore, Bd infection did not affect the duration of characteristic Sloughing behaviour, and Sloughing retained rhythmicity even at high infection loads. Although an increased Sloughing rate might be considered advantageous for Bd-infected animals, it does not appear to curb the progression of disease and may actually contribute to the loss of physiological homoeostasis seen in terminally ill frogs by further inhibiting water and electrolyte transport across the Skin. By measuring Sloughing rates directly for the first time, our results shed light on how Bd interacts with the physiological processes of the Skin and indicate that variation in Skin Sloughing frequency may play a role in the observed inter- and intraspecific variation in susceptibility to disease.
Michel E. B. Ohmer - One of the best experts on this subject based on the ideXlab platform.
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Phylogenetic investigation of Skin Sloughing rates in frogs: relationships with Skin characteristics and disease-driven declines
Proceedings of the Royal Society B: Biological Sciences, 2019Co-Authors: Michel E. B. Ohmer, Rebecca L. Cramp, Craig R. White, Peter S. Harlow, Michael Mcfadden, Andrés Merino-viteri, Allan P. Pessier, Phillip J. Bishop, Craig E. FranklinAbstract: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 t...
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A pathogenic Skin fungus and Sloughing exacerbate cutaneous water loss in amphibians
The Journal of Experimental Biology, 2018Co-Authors: Catherine J. M. Russo, Michel E. B. Ohmer, Rebecca L. Cramp, Craig E. FranklinAbstract:Abstract Batrachochytrium dendrobatidis ( Bd ) is a pathogenic fungus that causes the cutaneous, infectious disease chytridiomycosis and has been implicated in population declines of numerous anuran species worldwide. Proximate cause of death by chytridiomycosis is asystolic cardiac arrest as a consequence of severe disruption to electrolyte balance. Animals heavily infected with Bd also experience a disruption to their Skin Sloughing regime, indicating that core functions of the Skin, such as water retention, may be severely impacted. This study examined how Skin Sloughing, body size and Bd infection interact to influence water loss rates in five Australian frog species: Litoria caerulea , Limnodynastes peronii , Lechriodus fletcheri , Limnodynastes tasmaniensis and Platyplectrum ornatum . Rates of water loss more than doubled during Sloughing in L . caerulea . During active periods across all species, water loss rates were on average 232% higher in Bd infected frogs than in uninfected frogs. This indicates that dehydration stress may be a significant factor contributing to the morbidity of severely Bd infected anurans, a symptom that is then exacerbated by an increased rate of Sloughing. When taking size into account, smaller and/or juvenile anurans may be more at risk from dehydration due to Bd infection, as they lose a greater amount of water and slough more frequently than adults. This may in part explain the higher mortality rates typical for small and juvenile frogs infected with Bd . Understanding how Bd affects the core functions of the Skin, including rates of water loss, can improve our predictions of disease outcome in amphibians.
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Skin Sloughing in susceptible and resistant amphibians regulates infection with a fungal pathogen.
Scientific Reports, 2017Co-Authors: Michel E. B. Ohmer, Rebecca L. Cramp, Catherine J. M. Russo, Craig R. White, Craig E. FranklinAbstract:The fungal pathogen Batrachochytrium dendrobatidis (Bd) has been implicated in amphibian population declines globally. Given that Bd infection is limited to the Skin in post-metamorphic amphibians, routine Skin Sloughing may regulate infection. Skin Sloughing has been shown to reduce the number of cultivatable microbes on amphibian Skin, and Bd infection increases Skin Sloughing rates at high loads. However, it is unclear whether species specific differences in Skin Sloughing patterns could regulate Bd population growth on the Skin, and influence subsequent infection dynamics. We exposed five Australian frog species to Bd, and monitored Sloughing rates and infection loads over time. Sloughing reduced Bd load on the ventral Skin surface, in all five species, despite wide variation in susceptibility to disease. In the least susceptible species, an increase in Sloughing rate occurred at lower infection loads, and Sloughing reduced Bd load up to 100%, leading to infection clearance. Conversely, the drop in Bd load with Sloughing was only temporary in the more susceptible species. These findings indicate that the ability of Sloughing to act as an effective immune defence is species specific, and they have implications for understanding the pattern of Bd population growth on individual hosts, as well as population-level effects.
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Skin Sloughing rate increases with chytrid fungus infection load in a susceptible amphibian
Functional Ecology, 2014Co-Authors: Michel E. B. Ohmer, Rebecca L. Cramp, Craig R. White, Craig E. FranklinAbstract:Summary Amphibian chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is responsible for the greatest disease-driven loss of vertebrate biodiversity in recorded history. Understanding drivers of host susceptibility to this cutaneous disease is hindered by gaps in our knowledge of the host–pathogen relationship. One such overlooked aspect of susceptibility is variation in Skin maintenance processes, particularly Skin turnover via routine Sloughing. It has been suggested that Sloughing plays a role in immune defence, by removing Skin-associated microbes. Thus, Skin Sloughing may play an important role in the pathogenesis of chytridiomycosis. To determine the relationship between Skin Sloughing and disease progression, we exposed adult Australian green tree frogs (Litoria caerulea) to a local Bd strain and monitored Sloughing rates and individual infection loads on a naturalistic cycling temperature regime (15–23 °C). We determined Sloughing rates in real-time by using an array of infrared video cameras to film frog behaviour and monitored infection load before and after Sloughing by swabbing and analysis with quantitative PCR. We found that Sloughing rate increased with Bd infection load in infected frogs, but Sloughing itself did not affect Bd load on the ventral Skin surface. Furthermore, Bd infection did not affect the duration of characteristic Sloughing behaviour, and Sloughing retained rhythmicity even at high infection loads. Although an increased Sloughing rate might be considered advantageous for Bd-infected animals, it does not appear to curb the progression of disease and may actually contribute to the loss of physiological homoeostasis seen in terminally ill frogs by further inhibiting water and electrolyte transport across the Skin. By measuring Sloughing rates directly for the first time, our results shed light on how Bd interacts with the physiological processes of the Skin and indicate that variation in Skin Sloughing frequency may play a role in the observed inter- and intraspecific variation in susceptibility to disease.
Ohmer, Michel E. B. - One of the best experts on this subject based on the ideXlab platform.
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Phylogenetic investigation of Skin Sloughing rates in frogs: relationships with Skin characteristics and disease-driven declines
'The Royal Society', 2019Co-Authors: Ohmer, Michel E. B., Cramp, Rebecca L., White, Craig R., Harlow, Peter S., Mcfadden, Michael S., Merino-viteri Andrés, Pessier, Allan P., Wu, Nicholas C., Bishop, Phillip J., Franklin, Craig E.Abstract: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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Data from: Skin Sloughing in susceptible and resistant amphibians regulates infection with a fungal pathogen
2017Co-Authors: Ohmer, Michel E. B., Cramp, Rebecca L., Russo, Catherine J. M., White, Craig R., Franklin, Craig E.Abstract:The fungal pathogen Batrachochytrium dendrobatidis (Bd) has been implicated in amphibian population declines globally. Given that Bd infection is limited to the Skin in post-metamorphic amphibians, routine Skin Sloughing may regulate infection. Skin Sloughing has been shown to reduce the number of cultivatable microbes on amphibian Skin, and Bd infection increases Skin Sloughing rates at high loads. However, it is unclear whether species specific differences in Skin Sloughing patterns could regulate Bd population growth on the Skin, and influence subsequent infection dynamics. We exposed five Australian frog species to Bd, and monitored Sloughing rates and infection loads over time. Sloughing reduced Bd load on the ventral Skin surface, in all five species, despite wide variation in susceptibility to disease. In the least susceptible species, an increase in Sloughing rate occurred at lower infection loads, and Sloughing reduced Bd load up to 100%, leading to infection clearance. Conversely, the drop in Bd load with Sloughing was only temporary in the more susceptible species. These findings indicate that the ability of Sloughing to act as an effective immune defence is species specific, and they have implications for understanding the pattern of Bd population growth on individual hosts, as well as population-level effects
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Data from: Skin Sloughing rate increases with chytrid fungus infection load in a susceptible amphibian
2014Co-Authors: Ohmer, Michel E. B., Cramp, Rebecca L., White, Craig R., Franklin, Craig E.Abstract:1. Amphibian chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is responsible for the greatest disease-driven loss of vertebrate biodiversity in recorded history. Understanding drivers of host susceptibility to this cutaneous disease is hindered by gaps in our knowledge of the host–pathogen relationship. One such overlooked aspect of susceptibility is variation in Skin maintenance processes, particularly Skin turnover via routine Sloughing. It has been suggested that Sloughing plays a role in immune defence, by removing Skin-associated microbes. Thus, Skin Sloughing may play an important role in the pathogenesis of chytridiomycosis. 2. To determine the relationship between Skin Sloughing and disease progression, we exposed adult Australian green tree frogs (Litoria caerulea) to a local Bd strain and monitored Sloughing rates and individual infection loads on a naturalistic cycling temperature regime (15–23 °C). 3. We determined Sloughing rates in real-time by using an array of infrared video cameras to film frog behaviour and monitored infection load before and after Sloughing by swabbing and analysis with quantitative PCR. 4. We found that Sloughing rate increased with Bd infection load in infected frogs, but Sloughing itself did not affect Bd load on the ventral Skin surface. Furthermore, Bd infection did not affect the duration of characteristic Sloughing behaviour, and Sloughing retained rhythmicity even at high infection loads. 5. Although an increased Sloughing rate might be considered advantageous for Bd-infected animals, it does not appear to curb the progression of disease and may actually contribute to the loss of physiological homoeostasis seen in terminally ill frogs by further inhibiting water and electrolyte transport across the Skin. 6. By measuring Sloughing rates directly for the first time, our results shed light on how Bd interacts with the physiological processes of the Skin and indicate that variation in Skin Sloughing frequency may play a role in the observed inter- and intraspecific variation in susceptibility to disease
Cramp, Rebecca L. - One of the best experts on this subject based on the ideXlab platform.
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Mechanistic basis for the loss of water balance in green tree frogs infected with a fungal pathogen
'American Physiological Society', 2019Co-Authors: Wu, Nicholas C., Cramp, Rebecca L., Mckercher Callum, Franklin, Craig E.Abstract:Chytridiomycosis, a lethal Skin disease caused by the fungal pathogen () disrupts Skin function of amphibians, interfering with ionic and osmotic regulation. To regulate fungal loads, amphibians increase their rate of Skin Sloughing. However, Sloughing also causes a temporary loss of ionic and osmotic homeostasis due to disruption of the Skin, a key osmoregulatory organ. The combined effects of increased Sloughing frequency and chytridiomycosis contribute to the high rates of mortality from infections. However, the mechanisms responsible for the loss of cutaneous osmotic regulation remain unknown. We measured the changes in whole-animal water uptake rates, trans-cutaneous water fluxes across the ventral Skin, and the mRNA expression of epithelial water transport proteins (aquaporins, AQPs) and junctional proteins in -infected and uninfected Skin. We hypothesize that infected frogs would show reduction/inhibition in cutaneous water transporters responsible for regulating water balance, and Sloughing would exacerbate cutaneous water fluxes. We found that infected, non-Sloughing frogs had an impaired rate of water uptake and showed increased rates of water efflux across the ventral Skin. In uninfected frogs, the expression of AQPs and junction genes increased significantly with Sloughing which may assist in regulating cutaneous water movements and barrier function in the newly exposed Skin. In contrast, infected frogs did not show this post-Sloughing increase in AQP gene expression. The combination of increased Sloughing frequency, impaired water uptake rates and increased rates of water loss likely contributes to the loss of osmotic homeostasis in frogs infected with
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Phylogenetic investigation of Skin Sloughing rates in frogs: relationships with Skin characteristics and disease-driven declines
'The Royal Society', 2019Co-Authors: Ohmer, Michel E. B., Cramp, Rebecca L., White, Craig R., Harlow, Peter S., Mcfadden, Michael S., Merino-viteri Andrés, Pessier, Allan P., Wu, Nicholas C., Bishop, Phillip J., Franklin, Craig E.Abstract: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)
-
Data from: Skin Sloughing in susceptible and resistant amphibians regulates infection with a fungal pathogen
2017Co-Authors: Ohmer, Michel E. B., Cramp, Rebecca L., Russo, Catherine J. M., White, Craig R., Franklin, Craig E.Abstract:The fungal pathogen Batrachochytrium dendrobatidis (Bd) has been implicated in amphibian population declines globally. Given that Bd infection is limited to the Skin in post-metamorphic amphibians, routine Skin Sloughing may regulate infection. Skin Sloughing has been shown to reduce the number of cultivatable microbes on amphibian Skin, and Bd infection increases Skin Sloughing rates at high loads. However, it is unclear whether species specific differences in Skin Sloughing patterns could regulate Bd population growth on the Skin, and influence subsequent infection dynamics. We exposed five Australian frog species to Bd, and monitored Sloughing rates and infection loads over time. Sloughing reduced Bd load on the ventral Skin surface, in all five species, despite wide variation in susceptibility to disease. In the least susceptible species, an increase in Sloughing rate occurred at lower infection loads, and Sloughing reduced Bd load up to 100%, leading to infection clearance. Conversely, the drop in Bd load with Sloughing was only temporary in the more susceptible species. These findings indicate that the ability of Sloughing to act as an effective immune defence is species specific, and they have implications for understanding the pattern of Bd population growth on individual hosts, as well as population-level effects
-
Data from: Skin Sloughing rate increases with chytrid fungus infection load in a susceptible amphibian
2014Co-Authors: Ohmer, Michel E. B., Cramp, Rebecca L., White, Craig R., Franklin, Craig E.Abstract:1. Amphibian chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is responsible for the greatest disease-driven loss of vertebrate biodiversity in recorded history. Understanding drivers of host susceptibility to this cutaneous disease is hindered by gaps in our knowledge of the host–pathogen relationship. One such overlooked aspect of susceptibility is variation in Skin maintenance processes, particularly Skin turnover via routine Sloughing. It has been suggested that Sloughing plays a role in immune defence, by removing Skin-associated microbes. Thus, Skin Sloughing may play an important role in the pathogenesis of chytridiomycosis. 2. To determine the relationship between Skin Sloughing and disease progression, we exposed adult Australian green tree frogs (Litoria caerulea) to a local Bd strain and monitored Sloughing rates and individual infection loads on a naturalistic cycling temperature regime (15–23 °C). 3. We determined Sloughing rates in real-time by using an array of infrared video cameras to film frog behaviour and monitored infection load before and after Sloughing by swabbing and analysis with quantitative PCR. 4. We found that Sloughing rate increased with Bd infection load in infected frogs, but Sloughing itself did not affect Bd load on the ventral Skin surface. Furthermore, Bd infection did not affect the duration of characteristic Sloughing behaviour, and Sloughing retained rhythmicity even at high infection loads. 5. Although an increased Sloughing rate might be considered advantageous for Bd-infected animals, it does not appear to curb the progression of disease and may actually contribute to the loss of physiological homoeostasis seen in terminally ill frogs by further inhibiting water and electrolyte transport across the Skin. 6. By measuring Sloughing rates directly for the first time, our results shed light on how Bd interacts with the physiological processes of the Skin and indicate that variation in Skin Sloughing frequency may play a role in the observed inter- and intraspecific variation in susceptibility to disease