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Weitzman CL, Brown GP, Gibb K, Christian K. Cutaneous shedding in amphibians causes shifts in bacterial microbiomes. Integr Zool 2024. [PMID: 38897983 DOI: 10.1111/1749-4877.12858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Considerable research has focused on microbes on amphibian skin, as they act as the first line of defense against invading pathogens. This effort has generated substantial data on patterns across species, space, time, and ontogeny, alongside a growing list of beneficial antifungal symbionts. Though there is evidence of stability in amphibian skin microbial communities, there is also an indication that regular skin shedding reduces cultivable bacteria, with regrowth and recolonization in the period between sheds. This suggests that skin communities are in constant flux, and we lack an understanding of how the membership and structure of those communities are affected by shedding events. In this study, we conducted experiments on cane toads (Rhinella marina) to investigate the influence of shedding on skin microbiomes. We first used quantitative PCR to verify a positive correlation between bacterial loads and time in the days after shedding. We then resampled individuals over time to describe changes in community composition in the 38 h after shedding using amplicon sequencing. Similar to trends of bacterial loads, we found increases in alpha diversity over time after shedding, suggesting that shedding reduces bacterial diversity as it knocks down bacterial loads. During the 38-h period, community structure became similar to pre-shed communities in some individuals, but there was no consistent pattern in structural changes among individuals. In light of the amphibian chytridiomycosis pandemic, understanding how physiological events such as skin shedding affect beneficial bacteria and communities on amphibians would provide important insight into amphibian ecology.
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Affiliation(s)
- Chava L Weitzman
- Research Institute for the Environment and Livelihoods, Charles Darwin University, Casuarina, Northern Territory, Australia
| | - Gregory P Brown
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Karen Gibb
- Research Institute for the Environment and Livelihoods, Charles Darwin University, Casuarina, Northern Territory, Australia
| | - Keith Christian
- Research Institute for the Environment and Livelihoods, Charles Darwin University, Casuarina, Northern Territory, Australia
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2
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Getting ready for a long bath: skin permeability decreases prior to aquatic breeding in male toads. Naturwissenschaften 2021; 108:48. [PMID: 34601651 DOI: 10.1007/s00114-021-01761-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 09/17/2021] [Accepted: 09/20/2021] [Indexed: 10/20/2022]
Abstract
Vertebrate skin regulates exchanges between the organism and its environment and notably plays a fundamental role in regulating water fluxes. Dynamic changes of skin resistance to water fluxes are expected to occur in species that regularly shift between habitat types especially if these habitats differ in their hydric properties (e.g., terrestrial versus aquatic). We investigated changes of skin permeability using a study system (terrestrial toads) where reproduction induces a transition from terrestrial to freshwater habitats and a prolonged immersion that can last several weeks in males. In this system, the simultaneity between skin shedding and the onset of breeding suggests that the production of new integument layers prior to immersion for reproduction may regulate water influxes. We found that the skin permeability of male toads decreases significantly prior to breeding, suggesting that skin shedding at the onset of breeding regulates water fluxes to alleviate osmotic costs of immersion during reproduction. The continued decrease of skin permeability detected during breeding suggests that additional mechanisms interact with skin structure to further decrease permeability to water during a prolonged immersion. Future studies are required to assess whether changes in skin permeability to water tradeoffs with other skin characteristics (gas exchanges) relevant to aquatic breeding amphibians.
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3
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Medina-Ortiz K, López-Alvarez D, Navia F, Hansen T, Fierro L, Castaño S. Identification of Na +/K +-ATPase α/β isoforms in Rhinella marina tissues by RNAseq and a molecular docking approach at the protein level to evaluate α isoform affinities for bufadienolides. Comp Biochem Physiol A Mol Integr Physiol 2021; 254:110906. [PMID: 33476762 DOI: 10.1016/j.cbpa.2021.110906] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 01/12/2021] [Accepted: 01/12/2021] [Indexed: 12/24/2022]
Abstract
Na+/K+-ATPase (NKA) function is inhibited by Bufadienolides (BD), a group of cardiotonic steroids (CTS) primarily produced by anurans of the Bufonidae family, such as Rhinella marina. This study characterized the presence of α and β NKA subunit isoforms in R. marina via RNAseq in four tissues: oocytes, skin, heart, and skeletal muscle. Transcripts encoding three α-like isoforms (α1, α2, α3) and three β-like isoforms (β1, β2, β4) were identified. The amino acid sequence of α1-like isoform shared 99.4% identity with the α1 isoform previously published for R. marina. Sequences for α2, α3, and β4 from R. marina were previously unavailable. The first extracellular loop in the α2-like isoform in R. marina showed similar substitutions to those found in their susceptible homologues in other taxa (L/Q111T and S119T); in contrast, this same loop in α3-like isoform showed similar substitutions (Q111L and G120R) to those reported for toad-eating animals such as snakes, which suggests relatively lower affinity for CTS. Docking results showed that all three α-like isoforms identified in R. marina transcriptomes have low affinity to CTS compared to the susceptible α1 isoform of Sus scrofa (pig), with α1-like isoform being the most resistant. The tissue-specific RNAseq results showed the following expression of NKA α-like and β-like subunit isoforms: Oocytes expressed α1 and β1; skin α1, β1, and low levels of β2; heart α1, α3, and β1; skeletal muscle α1, β4, with low levels of α2, α3, and β1. R. marina could be used as an important model for future structural, functional and pharmacological studies of NKA and its isoforms.
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Affiliation(s)
- Katherine Medina-Ortiz
- Laboratorio de Herpetología y Toxinología, Department of Physiological Sciences, Universidad del Valle, Cali, Colombia.
| | - Diana López-Alvarez
- Laboratorio de Herpetología y Toxinología, Department of Physiological Sciences, Universidad del Valle, Cali, Colombia
| | - Felipe Navia
- Laboratorio de Herpetología y Toxinología, Department of Physiological Sciences, Universidad del Valle, Cali, Colombia
| | - Thomas Hansen
- Laboratorio de Herpetología y Toxinología, Department of Physiological Sciences, Universidad del Valle, Cali, Colombia
| | - Leonardo Fierro
- Laboratorio de Herpetología y Toxinología, Department of Physiological Sciences, Universidad del Valle, Cali, Colombia
| | - Santiago Castaño
- Laboratorio de Herpetología y Toxinología, Department of Physiological Sciences, Universidad del Valle, Cali, Colombia.
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Ohmer MEB, Cramp RL, White CR, Harlow PS, McFadden MS, Merino-Viteri A, Pessier AP, Wu NC, Bishop PJ, Franklin CE. Phylogenetic investigation of skin sloughing rates in frogs: relationships with skin characteristics and disease-driven declines. Proc Biol Sci 2020; 286:20182378. [PMID: 30963925 DOI: 10.1098/rspb.2018.2378] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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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Affiliation(s)
- Michel E B Ohmer
- 1 School of Biological Sciences, The University of Queensland , St Lucia, Queensland 4072 , Australia.,2 Department of Biological Sciences, University of Pittsburgh , Pittsburgh, PA 15260 , USA
| | - Rebecca L Cramp
- 1 School of Biological Sciences, The University of Queensland , St Lucia, Queensland 4072 , Australia
| | - Craig R White
- 3 School of Biological Sciences, Monash University, Centre for Geometric Biology , Victoria 3800 , Australia
| | - Peter S Harlow
- 4 Taronga Conservation Society Australia, Herpetofauna Division , Mosman, New South Wales , Australia
| | - Michael S McFadden
- 4 Taronga Conservation Society Australia, Herpetofauna Division , Mosman, New South Wales , Australia
| | - Andrés Merino-Viteri
- 5 Laboratorio de Ecofisiología/Museo de Zoología (QCAZ), Escuela de Ciencias Biológicas, Pontificia Universidad Católica del Ecuador , Quito , Ecuador
| | - Allan P Pessier
- 6 Department of Veterinary Microbiology and Pathology, College of Veterinary Medicine, Washington State University , Pullman, WA 99164 , USA
| | - Nicholas C Wu
- 1 School of Biological Sciences, The University of Queensland , St Lucia, Queensland 4072 , Australia
| | - Phillip J Bishop
- 7 Department of Zoology, University of Otago , Dunedin , New Zealand
| | - Craig E Franklin
- 1 School of Biological Sciences, The University of Queensland , St Lucia, Queensland 4072 , Australia
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5
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Burggren W, Bautista N. Invited review: Development of acid-base regulation in vertebrates. Comp Biochem Physiol A Mol Integr Physiol 2019; 236:110518. [DOI: 10.1016/j.cbpa.2019.06.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Revised: 06/24/2019] [Accepted: 06/25/2019] [Indexed: 12/26/2022]
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6
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Wu NC, McKercher C, Cramp RL, Franklin CE. Mechanistic basis for loss of water balance in green tree frogs infected with a fungal pathogen. Am J Physiol Regul Integr Comp Physiol 2019; 317:R301-R311. [PMID: 31141416 DOI: 10.1152/ajpregu.00355.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Chytridiomycosis, a lethal skin disease caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), 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 Bd infections. However, the mechanisms responsible for the loss of cutaneous osmotic regulation remain unknown. We measured the changes in whole animal water uptake rates, in vitro transcutaneous water fluxes across the ventral skin, and the mRNA expression of epithelial water transport proteins (aquaporins, AQPs) and junctional proteins in Bd-infected and uninfected Litoria caerulea 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, nonsloughing frogs had an impaired rate of water uptake and showed increased rates of in vitro 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 postsloughing 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 Bd.
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Affiliation(s)
- Nicholas C Wu
- School of Biological Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - Callum McKercher
- School of Biological Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - Rebecca L Cramp
- School of Biological Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - Craig E Franklin
- School of Biological Sciences, University of Queensland, Brisbane, Queensland, Australia
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7
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Doody KA, Ohmer ME, Cramp RL, Franklin CE. Do Frogs Infected with Batrachochytrium dendrobatidis Avoid Water While Sloughing? HERPETOLOGICA 2019. [DOI: 10.1655/d-18-00014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Kathleen A. Doody
- School of Biological Sciences, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Michel E.B. Ohmer
- School of Biological Sciences, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Rebecca L. Cramp
- School of Biological Sciences, The University of Queensland, St. Lucia, QLD 4072, Australia
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8
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Pokharel K, Weldenegodguad M, Popov R, Honkatukia M, Huuki H, Lindeberg H, Peippo J, Reilas T, Zarovnyaev S, Kantanen J. Whole blood transcriptome analysis reveals footprints of cattle adaptation to sub-arctic conditions. Anim Genet 2019; 50:217-227. [PMID: 30957254 PMCID: PMC6593690 DOI: 10.1111/age.12783] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/04/2019] [Indexed: 12/17/2022]
Abstract
Indigenous cattle breeds in northern Eurasia have adapted to harsh climate conditions. The local breeds are important genetic resources with cultural and historical heritages, and therefore, their preservation and genetic characterization are important. In this study, we profiled the whole‐blood transcriptome of two native breeds (Northern Finncattle and Yakutian cattle) and one commercial breed (Holstein) using high‐throughput RNA sequencing. More than 15 000 genes were identified, of which two, 89 and 162 genes were significantly upregulated exclusively in Northern Finncattle, Yakutian cattle and Holstein cattle respectively. The functional classification of these significantly differentially expressed genes identified several biological processes and pathways related to signalling mechanisms, cell differentiation and host–pathogen interactions that, in general, point towards immunity and disease resistance mechanisms. The gene expression pattern observed in Northern Finncattle was more similar to that of Yakutian cattle, despite sharing similar living conditions with the Holstein cattle included in our study. In conclusion, our study identified unique biological processes in these breeds that may have helped them to adapt and survive in northern and sub‐arctic environments.
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Affiliation(s)
- K Pokharel
- Production Systems, Natural Resources Institute Finland (Luke), Myllytie 1, Jokioinen, FI-31600, Finland
| | - M Weldenegodguad
- Production Systems, Natural Resources Institute Finland (Luke), Myllytie 1, Jokioinen, FI-31600, Finland.,Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 1627, Kuopio, FI-70311, Finland
| | - R Popov
- Yakutian Research Institute of Agriculture (FGBNU Yakutskij NIISH), ul. Bestyzhevo-Marlinskogo 23/1, Yakutsk, 67001, The Sakha Republic (Yakutia), Russia
| | - M Honkatukia
- Production Systems, Natural Resources Institute Finland (Luke), Myllytie 1, Jokioinen, FI-31600, Finland.,The Nordic Genetic Resources Center (Nordgen), P.O. Box 115, Ås, NO-1431, Norway
| | - H Huuki
- Production Systems, Natural Resources Institute Finland (Luke), Myllytie 1, Jokioinen, FI-31600, Finland
| | - H Lindeberg
- Production Systems, Natural Resources Institute Finland (Luke), Halolantie 31A, Maaninka, FI-71750, Finland
| | - J Peippo
- Production Systems, Natural Resources Institute Finland (Luke), Myllytie 1, Jokioinen, FI-31600, Finland
| | - T Reilas
- Production Systems, Natural Resources Institute Finland (Luke), Myllytie 1, Jokioinen, FI-31600, Finland
| | - S Zarovnyaev
- GBU Saha Agroplem, ul. Ordzhonkidze 20/204, Yakutsk, 67700, The Sakha Republic (Yakutia), Russia
| | - J Kantanen
- Production Systems, Natural Resources Institute Finland (Luke), Myllytie 1, Jokioinen, FI-31600, Finland
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9
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Wu NC, Cramp RL, Ohmer MEB, Franklin CE. Epidermal epidemic: unravelling the pathogenesis of chytridiomycosis. ACTA ACUST UNITED AC 2019; 222:jeb.191817. [PMID: 30559300 DOI: 10.1242/jeb.191817] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 12/05/2018] [Indexed: 12/18/2022]
Abstract
Chytridiomycosis, a lethal fungal skin disease of amphibians, fatally disrupts ionic and osmotic homeostasis. Infected amphibians increase their skin shedding rate (sloughing) to slow pathogen growth, but the sloughing process also increases skin permeability. Healthy amphibians increase active ion uptake during sloughing by increasing ion transporter abundance to offset the increased skin permeability. How chytridiomycosis affects the skin function during and between sloughing events remains unknown. Here, we show that non-sloughing frogs with chytridiomycosis have impaired cutaneous sodium uptake, in part because they have fewer sodium transporters in their skin. Interestingly, sloughing was associated with a transient increase in sodium transporter activity and abundance, suggesting that the newly exposed skin layer is initially fully functional until the recolonization of the skin by the fungus again impedes cutaneous function. However, the temporary restoration of skin function during sloughing does not restore ionic homeostasis, and the underlying loss of ion uptake capacity is ultimately detrimental for amphibians with chytridiomycosis.
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Affiliation(s)
- Nicholas C Wu
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Rebecca L Cramp
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Michel E B Ohmer
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Craig E Franklin
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
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10
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Christian K, Weitzman C, Rose A, Kaestli M, Gibb K. Ecological patterns in the skin microbiota of frogs from tropical Australia. Ecol Evol 2018; 8:10510-10519. [PMID: 30464823 PMCID: PMC6238143 DOI: 10.1002/ece3.4518] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 08/14/2018] [Accepted: 08/17/2018] [Indexed: 12/20/2022] Open
Abstract
The microbiota of frog skin can play an important role in protecting against diseases and parasites. The frog skin microbial community represents a complex mix of microbes that are promoted by the chemical environment of the frog skin and influenced by the animal's immediate past environment. The microbial communities of six species of frogs sampled from the campus of Charles Darwin University (CDU) were more similar within species than between species. The microbiota of the introduced cane toad (Rhinella marina) was most dissimilar among the species. Pairwise comparisons showed that the microbial communities of each species were different, except for the terrestrial Litoria nasuta and the arboreal L. rothii. The microbial communities of the six species were not related to ecological habit (arboreal or terrestrial), and neither was the alpha diversity of the microbes. The core microbes (defined as being on ≥90% of individuals of a species or group) were significantly different among all species, although 89 microbial operational taxonomic units (OTUs) were core microbes for all six species at CDU. Two species, Rhinella marina and Litoria rothii, were sampled at additional sites approximately 10 and 30 km from CDU. The microbial communities and the core OTU composition were different among the sites, but there were nevertheless 194 (R. marina) and 181 (L. rothii) core OTUs present at all three sites. Thus, the core microbiota varied with respect to geographic range and sample size.
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Affiliation(s)
- Keith Christian
- Research Institute for the Environment and LivelihoodsCharles Darwin UniversityDarwinNorthern TerritoryAustralia
| | | | - Alea Rose
- Research Institute for the Environment and LivelihoodsCharles Darwin UniversityDarwinNorthern TerritoryAustralia
| | - Mirjam Kaestli
- Research Institute for the Environment and LivelihoodsCharles Darwin UniversityDarwinNorthern TerritoryAustralia
| | - Karen Gibb
- Research Institute for the Environment and LivelihoodsCharles Darwin UniversityDarwinNorthern TerritoryAustralia
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11
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Langowski JKA, Dodou D, Kamperman M, van Leeuwen JL. Tree frog attachment: mechanisms, challenges, and perspectives. Front Zool 2018; 15:32. [PMID: 30154908 PMCID: PMC6107968 DOI: 10.1186/s12983-018-0273-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 06/29/2018] [Indexed: 11/16/2022] Open
Abstract
Tree frogs have the remarkable ability to attach to smooth, rough, dry, and wet surfaces using their versatile toe pads. Tree frog attachment involves the secretion of mucus into the pad-substrate gap, requiring adaptations towards mucus drainage and pad lubrication. Here, we present an overview of tree frog attachment, with focus on (i) the morphology and material of the toe pad; (ii) the functional demands on the toe pad arising from ecology, lifestyle, and phylogenetics; (iii) experimental data of attachment performance such as adhesion and friction forces; and (iv) potential perspectives on future developments in the field. By revisiting reported data and observations, we discuss the involved mechanisms of attachment and propose new hypotheses for further research. Among others, we address the following questions: Do capillary and hydrodynamic forces explain the strong friction of the toe pads directly, or indirectly by promoting dry attachment mechanisms? If friction primarily relies on van der Waals (vdW) forces instead, how much do these forces contribute to adhesion in the wet environment tree frogs live in and what role does the mucus play? We show that both pad morphology and measured attachment performance suggest the coaction of several attachment mechanisms (e.g. capillary and hydrodynamic adhesion, mechanical interlocking, and vdW forces) with situation-dependent relative importance. Current analytical models of capillary and hydrodynamic adhesion, caused by the secreted mucus and by environmental liquids, do not capture the contributions of these mechanisms in a comprehensive and accurate way. We argue that the soft pad material and a hierarchical surface pattern on the ventral pad surface enhance the effective contact area and facilitate gap-closure by macro- to nanoscopic drainage of interstitial liquids, which may give rise to a significant contribution of vdW interactions to tree frog attachment. Increasing the comprehension of the complex mechanism of tree frog attachment contributes to a better understanding of other biological attachment systems (e.g. in geckos and insects) and is expected to stimulate the development of a wide array of bioinspired adhesive applications.
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Affiliation(s)
- Julian K. A. Langowski
- Experimental Zoology Group, Department of Animal Sciences, Wageningen University & Research, De Elst 1, Wageningen, 6708 WD The Netherlands
| | - Dimitra Dodou
- Department of BioMechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Mekelweg 2, Delft, 2628 CD The Netherlands
| | - Marleen Kamperman
- Physical Chemistry and Soft Matter, Department of Agrotechnology and Food Sciences, Wageningen University & Research, Stippeneng 4, Wageningen, 6708 WE The Netherlands
| | - Johan L. van Leeuwen
- Experimental Zoology Group, Department of Animal Sciences, Wageningen University & Research, De Elst 1, Wageningen, 6708 WD The Netherlands
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12
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Russo CJM, Ohmer MEB, Cramp RL, Franklin CE. A pathogenic skin fungus and sloughing exacerbate cutaneous water loss in amphibians. ACTA ACUST UNITED AC 2018; 221:221/9/jeb167445. [PMID: 29752415 DOI: 10.1242/jeb.167445] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2017] [Accepted: 03/13/2018] [Indexed: 11/20/2022]
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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Affiliation(s)
- Catherine J M Russo
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Michel E B Ohmer
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Rebecca L Cramp
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Craig E Franklin
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
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13
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Wu NC, Cramp RL, Franklin CE. Body size influences energetic and osmoregulatory costs in frogs infected with Batrachochytrium dendrobatidis. Sci Rep 2018; 8:3739. [PMID: 29487313 PMCID: PMC5829222 DOI: 10.1038/s41598-018-22002-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 02/06/2018] [Indexed: 12/18/2022] Open
Abstract
Sloughing maintains the skins integrity and critical functionality in amphibians. Given the behavioural, morphological and osmoregulatory changes that accompany sloughing, this process is likely to be physiologically costly. Chytridiomycosis, a cutaneous disease of amphibians caused by the fungus Batrachochytrium dendrobatidis (Bd), disrupts skin function and increases sloughing rates. Moreover, mortality rates from chytridiomycosis are significantly higher in juveniles and so we hypothesised that smaller individuals maybe more susceptible to chytridiomycosis because of allometric scaling effects on the energetic and osmoregulatory costs of sloughing. We measured in-vivo cutaneous ion loss rates and whole animal metabolic rate (MR) of Green tree frogs, Litoria caerulea, over a range of body sizes both infected and uninfected frogs during sloughing. Infected animals had a greater rate of ion loss and mass-specific MR during non-sloughing periods but there were no additional effects of sloughing on either of these parameters. There were also significant interactions with body size and Bd load indicating that smaller animals with higher Bd loads have greater rates of ion loss and higher energetic demands. Our results shed light on why smaller Bd-infected anurans often exhibit greater physiological disruption than larger individuals.
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Affiliation(s)
- Nicholas C Wu
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Rebecca L Cramp
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Craig E Franklin
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, 4072, Australia.
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14
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Ohmer MEB, Cramp RL, Russo CJM, White CR, Franklin CE. Skin sloughing in susceptible and resistant amphibians regulates infection with a fungal pathogen. Sci Rep 2017; 7:3529. [PMID: 28615642 PMCID: PMC5471217 DOI: 10.1038/s41598-017-03605-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 05/05/2017] [Indexed: 11/09/2022] Open
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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Affiliation(s)
- Michel E B Ohmer
- The University of Queensland, School of Biological Sciences, St. Lucia, QLD 4072, Australia. .,University of Pittsburgh, Department of Biological Sciences, Pittsburgh, PA, 15260, United States.
| | - Rebecca L Cramp
- The University of Queensland, School of Biological Sciences, St. Lucia, QLD 4072, Australia
| | - Catherine J M Russo
- The University of Queensland, School of Biological Sciences, St. Lucia, QLD 4072, Australia
| | - Craig R White
- Monash University, Centre for Geometric Biology, School of Biological Sciences, Monash, VIC 3800, Australia
| | - Craig E Franklin
- The University of Queensland, School of Biological Sciences, St. Lucia, QLD 4072, Australia
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Knight K. Salt pumps protect leaky toads when replacing skin. J Exp Biol 2017. [DOI: 10.1242/jeb.162628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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