Biology and Diseases of Amphibians

O’Rourke, Dorcas P.; Rosenbaum, Matthew D.

doi:10.1016/b978-0-12-409527-4.00018-3

Cited by 23 publications

(9 citation statements)

References 124 publications

(188 reference statements)

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“…It is clear, however, that cancer occurs throughout vertebrate and invertebrate taxa, both in the wild and in captivity ([ 12 – 16 ] but see [ 17 ] for potential exception in long-lived decapods). Specifically, there are considerable data from captive populations showing neoplasia in amphibians [ 18 ] and reptiles [ 19 , 20 ], and captive reptiles have been argued to have an incidence of neoplasia comparable with that of mammals and birds [ 16 , 21 ]. In fact, a study by Madsen et al [ 20 ] demonstrates that reptiles in French zoo parks even have significantly higher cancer frequency than mammals.…”

Section: Introductionmentioning

confidence: 99%

Ectothermic telomeres: it's time they came in from the cold

Olsson

Wapstra

Friesen

2018

Phil. Trans. R. Soc. B

122

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We review the evolutionary ecology and genetics of telomeres in taxa that cannot elevate their body temperature to a preferred level through metabolism but do so by basking or seeking out a warm environment. This group of organisms contains all living things on earth, apart from birds and mammals. One reason for our interest in this synthetic group is the argument that high, stable body temperature increases the risk of malignant tumours if long, telomerase-restored telomeres make cells ‘live forever’. If this holds true, ectotherms should have significantly lower cancer frequencies. We discuss to what degree there is support for this ‘anti-cancer’ hypothesis in the current literature. Importantly, we suggest that ectothermic taxa, with variation in somatic telomerase expression across tissue and taxa, may hold the key to understanding ongoing selection and evolution of telomerase dynamics in the wild. We further review endotherm-specific effects of growth on telomeres, effects of autotomy (‘tail dropping’) on telomere attrition, and costs of maintaining sexual displays measured in telomere attrition. Finally, we cover plant ectotherm telomeres and life histories in a separate ‘mini review’.This article is part of the theme issue ‘Understanding diversity in telomere dynamics'.

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Section: Introductionmentioning

confidence: 99%

Ectothermic telomeres: it's time they came in from the cold

Olsson

Wapstra

Friesen

2018

Phil. Trans. R. Soc. B

122

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“…According to the World Organisation for Animal Health, the presented clinical and pathological findings are (30), once no other virus types have been associated with similar pathological findings (2,11,25). Minor findings contained focal caseating microgranulomas in the liver, spleen, and kidneys, suggesting Mycobacteria, already reported in the same geographic region (3,23), and cystic gastric helminths, suggesting Physaloptera sp.…”

Section: Discussionmentioning

confidence: 87%

Marked systemic necrotizing disease in a Leptodactylus vastus (Anura: Leptodactylidae) from an urban reserve in northeastern Brazil

Braga,

Eleutério,

Lima

et al. 2023

BJVP

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The decline of amphibian populations concerns scientists worldwide and has been related to the spreading infectious diseases, among other environmental factors. Acute mass mortality with hemorrhagic and necrotic lesions has been described and associated with wild amphibian viruses. These diseases were first recorded in Central America and Australia in the early 1990s and later in Brazilian Atlantic Forest fragments. Epizootiological data on these infections must be included in other Brazilian phytogeographic regions and domains. This work aimed to report a systemic necrotic morbid state in a native Leptodactylus vastus from an urban reserve in northeastern Brazil, describing clinical and pathological findings and discussing its importance and likely etiologies. An adult L. vastus presented an erythematous oral cavity with multifocal point-like erosions, sublingual congested vessels, oropharyngeal edema, and mild esophageal mucosal prolapse. After therapeutic protocol, the patient showed no improvement; then, he was humanely euthanized. Necropsy demonstrated moderate to marked multicentric chronic necrotizing lesions. Histopathology revealed diffuse necrotic tissues with a few intracytoplasmic amphophilic inclusions in cellular remnants, with minor hemoparasites, helminths, and bacterial granulomatous coinfections. Clinical and pathological findings suggested a major chronic viral infection with minor coinfections. In the current case, confirmation of etiology struggled with financial and logistic limitations. Future partnerships will enable definitive diagnostics. This is the first record of systemic necrotizing disease in a wild frog in Ceará state, northeastern Brazil, and it is a red flag to emerging infectious diseases surveillance in this geographic area.

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“…During transport or captivity, amphibians are vulnerable to injuries, and their wounds are often fatal due to secondary infections from ubiquitous gram-negative bacteria, such as Aeromonas , combined with sickness-induced anorexia ( 1 – 3 ). Furthermore, fungal pathogens such as Batrachochytrium dendrobatidis or Batrachochytrium salamandrivorans invade the skin, and prolonged infections are highly lethal in many species of frogs and salamanders ( 6 , 48 – 50 ). Factors that improve wound healing and immunity broadly across amphibians are needed ( 3 ), especially those that do not cause adverse side effects or concerns about persistence in wastewaters.…”

Section: Discussionmentioning

confidence: 99%

“…In amphibians, the skin is an important organ for respiration and immunity, but it is also easily injured and vulnerable to infection. Current treatments for skin wounds or diseases in captive amphibians are limited to antibiotics and antifungals, though pharmacokinetics and effective dosages are not well understood (4)(5)(6). While these are effective at preventing infection, they do not explicitly accelerate wound healing.…”

Section: Introductionmentioning

confidence: 99%

Evolutionary conservation of leptin effects on wound healing in vertebrates: Implications for veterinary medicine

et al. 2022

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In mammals, the cytokine hormone leptin promotes wound healing by increasing inflammation, cellular recruitment, angiogenic regrowth, and re-epithelialization; however, it is not known whether leptin has conserved actions on wound healing in other vertebrates. Here, we tested the hypothesis that leptin promotes both the quality and speed of wound healing in the South African clawed frog, Xenopus laevis. First, fluorescent immunohistochemistry using a polyclonal antibody specific to Xenopus leptin showed that in juvenile dorsal skin, leptin protein is expressed in the dorsal epidermal layer, as well in blood vessel endothelial cells and sensory nerves that run along the base of the dermis. Injection of recombinant Xenopus leptin (rXleptin) stimulates phosphorylated STAT3 (pSTAT3), indicative of leptin-activated JAK/STAT signaling in the epidermis. Similar to mammals, leptin protein expression increases at the wound site after injury of the epidermis. We then cultured “punch-in-a-punch” full-thickness dorsal skin explants in three doses of rXleptin (0, 10, and 100 ng/ml) and showed that leptin treatment doubled the rate of wound closure after 48 h relative to skin punches cultured without leptin. Food restriction prior to wound explant culture reduced the amount of wound closure, but leptin injection prior to euthanasia rescued closure to similar control levels. Leptin treatment also significantly reduced bacterial infection of these epidermal punches by 48 h in culture. This study shows that leptin is likely an endogenous promoter of wound healing in amphibians. Leptin-based therapies have the potential to expedite healing and reduce the incidence of secondary infections without toxicity issues, the threat of antibiotic resistance, or environmental antibiotic contamination. The conservation of leptin’s actions on wound healing also suggests that it may have similar veterinary applications for other exotic species.

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Biology and Diseases of Amphibians

Cited by 23 publications

References 124 publications

Ectothermic telomeres: it's time they came in from the cold

Ectothermic telomeres: it's time they came in from the cold

Marked systemic necrotizing disease in a Leptodactylus vastus (Anura: Leptodactylidae) from an urban reserve in northeastern Brazil

Evolutionary conservation of leptin effects on wound healing in vertebrates: Implications for veterinary medicine

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