MOULTING IN THE ANURA: THE NORMAL MOULTING CYCLE OF <i>BUFO REGULARIS</i> REUSS

Taylor, Sonya; Ewer, D. W.

doi:10.1111/j.1096-3642.1956.tb00482.x

Cited by 11 publications

(17 citation statements)

References 16 publications

(16 reference statements)

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“…Sloughing in Rhinella marina was strongly affected by temperature with the intermoult interval of animals maintained at 10−20°C twice that of animals maintained at 20−30°C. These results are consistent with those of Taylor & Ewer (1956), who showed that in Bufo regularis maintained at 20°C, sloughing occurred half as frequently as in animals maintained at 30°C. Moreover, in B. regularis, sloughing frequency decreased even more dramatically at temperatures below 20°C, with animals at 15°C sloughing 4 times less frequently than animals maintained at 30°C.…”

Section: Discussionsupporting

confidence: 92%

“…The effectiveness of sloughing in regulating microbial abundance will depend to a large degree on the frequency of sloughing, which, as this and earlier studies (e.g. Taylor & Ewer 1956) show, is influenced by ambient temperature. Sloughing in Rhinella marina was strongly affected by temperature with the intermoult interval of animals maintained at 10−20°C twice that of animals maintained at 20−30°C.…”

Section: Discussionsupporting

confidence: 53%

“…In amphibians, the stratum corneum is shed on a regular basis (Larsen 1976, Withers 1995; moreover, unlike mammals, sloughing of the stratum corneum in amphibians is usually entire (i.e. all of the stratum corneum is shed at once) (Taylor & Ewer 1956, Ling 1972, Larsen 1976, Withers 1995. As such, sloughing could play a significant role in regulating the abundance and persistence of microbes, both beneficial and pathogenic, at the body's surface.…”

Section: Resale or Republication Not Permitted Without Written Consenmentioning

confidence: 99%

“…Whether other amphibian species are similarly unable to acclimate sloughing frequency to low temperatures is difficult to say, as data on the effects of prolonged exposure to low temperature on sloughing are limited. Data from Taylor & Ewer (1956), at least, suggest acclimation of sloughing to low temperatures in Bufo regularis is also unlikely, with no increase in sloughing frequency over time in animals maintained at 20°C.Regardless of whether sloughing occurs frequently enough to limit pathogen abundance, the risk of disease will obviously also depend on the thermal biology of the pathogen, specifically the rate at which a microbe grows and multiplies. Microbial growth and reproduction rates are highly temperature-dependent; however, different microbes will have different optimal temperatures for growth and development.…”

mentioning

confidence: 99%

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Changes in cutaneous microbial abundance with sloughing: possible implications for infection and disease in amphibians

Meyer¹,

Cramp²,

Bernal³

et al. 2012

Dis. Aquat. Org.

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The emergence of disease as a significant global threat to amphibian diversity has generated considerable interest in amphibian defenses against cutaneous microbial infection and disease. To date, however, the influence of sloughing on the susceptibility of amphibians to infection and disease has been largely overlooked. To investigate the potential for sloughing to regulate topical microbial loads, the abundance of cultivable cutaneous bacteria and fungi in the cane toad Rhinella marina were compared before and after sloughing. Toads were also exposed to fluctuating thermal regimes (10−20 and 20−30°C) and variable photoperiods to investigate possible effects of season and climate on sloughing periodicity. Sloughing substantially reduced the abundance of cultivable cutaneous bacteria and fungi by up to 100%. The intermoult interval of toads maintained at 10−20°C was twice that of animals at 20−30°C and did not appear to thermally acclimate. Photoperiod had no discernable influence on sloughing periodicity. Results of this study suggest that normal sloughing cycles could play a significant role in controlling the persistence and build-up of cutaneous microbes, including pathogens. The loss of non-pathogenic commensal and protective skin microbiota after sloughing may also influence host susceptibility to cutaneous pathogens. We suggest that the spatio-temporal dynamics of chytridiomycosis, the widespread and often fatal disease caused by the fungal pathogen Batrachochytrium dendrobatidis, are related to temperature not only because of its effect on the growth of the fungus, but also because of its effect on the frequency of host sloughing.KEY WORDS: Skin · Shedding · Temperature · Rhinella marina · Pathogen · Batrachochytrium dendrobatidis · Commensal microbe · Epidermis · Cutaneous Resale or republication not permitted without written consent of the publisherDis Aquat Org 101: [235][236][237][238][239][240][241][242] 2012 and microbes adherent to the most peripheral skin layers can be shed with the shed keratinocytes (Dahl 1993). In amphibians, the stratum corneum is shed on a regular basis (Larsen 1976, Withers 1995; moreover, unlike mammals, sloughing of the stratum corneum in amphibians is usually entire (i.e. all of the stratum corneum is shed at once) (Taylor & Ewer 1956, Ling 1972, Larsen 1976, Withers 1995. As such, sloughing could play a significant role in regulating the abundance and persistence of microbes, both beneficial and pathogenic, at the body's surface.To investigate the influence of sloughing on microbial abundances on amphibian skin, we examined changes in the abundance of cultivable cutaneous microbes post-sloughing in cane toads Rhinella marina (Linnaeus, 1758). As ectotherms, physiological processes such as sloughing are likely to be affected by environmental factors such as temperature and day length. Seasonal differences in temperature and photoperiod may, therefore, affect sloughing periodicity and in turn contribute to the seasonality of some amphibian diseases (Berger et...

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Section: Discussionsupporting

confidence: 92%

Section: Discussionsupporting

confidence: 53%

Section: Resale or Republication Not Permitted Without Written Consenmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Changes in cutaneous microbial abundance with sloughing: possible implications for infection and disease in amphibians

Meyer¹,

Cramp²,

Bernal³

et al. 2012

Dis. Aquat. Org.

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“…Observed sloughing behaviour was consistent across individuals and aligns with previously published descriptions (Taylor & Ewer 1956;Larsen 1976; Despite this, the duration of sloughing (min, log-transformed) was not significantly longer in Table 2.2). This indicates that the stratum corneum of exposed frogs was no longer being sloughed in one piece, or the action of sloughing was less effective in exposed frogs.…”

Section: Sloughing Behavioursupporting

confidence: 87%

Interactions between amphibian skin sloughing and a cutaneous fungal disease: infection progression, immune defence, and phylogenetic patterns

Ohmer¹

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Worldwide, there has been an unprecedented rise in emerging infectious diseases of wildlife, and this has contributed to a widespread biodiversity crisis. Amphibian populations, in particular, are threatened by the fungal pathogen Batrachochytrium dendrobatidis (Bd), which in post-metamorphic animals only infects the skin, and causes the potentially lethal disease chytridiomycosis. Amphibians regularly slough their skin, and in doing so remove many skinassociated microbes. Thus, skin sloughing may play an important role in the pathogenesis of chytridiomycosis. To investigate this association, the influence of Bd infection on amphibian skin sloughing, and the role of sloughing in regulating infection, was examined. Furthermore, to better understand the variation in skin sloughing rates across species and ecological groups, and make inferences about the role of this process in susceptibility to this fungal disease, amphibian skin structure and function was investigated within a phylogenetic context. To determine the relationship between skin sloughing and disease progression (chapter 2), adult green tree frogs (Litoria caerulea) were exposed to an Australian Bd strain, and sloughing rates and infection load were monitored on a naturalistic cycling temperature regime (15 -23˚C).Sloughing rates were determined by filming frogs and infection intensity was monitored before and after sloughing with conventional swabbing and quantitative PCR. Sloughing rate was found to increase with Bd infection load in infected frogs, but sloughing itself did not affect Bd load on the ventral skin surface. Although a faster sloughing rate might be considered advantageous for Bdinfected animals, it does not appear to curb the progression of disease in susceptible species. In fact, sloughing may actually contribute to the loss of physiological homeostasis seen in terminally ill frogs by further inhibiting water and electrolyte transport across the skin.In some species less susceptible to chytridiomycosis, it has been demonstrated that Bd growth remains epibiotic, without penetrating the underlying epidermal layers. Therefore, sloughing may more effectively remove Bd zoospores in less susceptible species (chapter 3). To test this hypothesis, five Australian frog species, Lit. caerulea, Platyplectrum ornatum, Lechriodus fletcheri, Limnodynastes peronii, and Lim. tasmaniensis, were exposed to an Australian Bd strain, and their sloughing rates and infection loads monitored over time. Utilising an improved methodology to remove any artefacts from the swabbing itself, sloughing was found to reduce Bd load on the ventral skin surface, in all five species, despite wide ranging variation in susceptibility to Bd infection and subsequent disease. In less susceptible species, sloughing reduced Bd load up to 100%, leading to infection clearance. However, the drop in Bd load was only temporary in susceptible species, potentially due to the invasive growth of Bd in skin layers underlying the ii stratum corneum in these species. If less suscept...

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Epidermal keratinization in the salamander and a comparison with other amphibia

Spearman

1968

Journal of Morphology

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In a variety of amphibians examined the stratum corneum was one cell in depth, although in Xenopus it was up to three cells deep. The flattened horny cells were closely fused together along their lateral membranes to form a continuous sheet. Disulphide bonds of keratin were most concentrated in the peripheral cytoplasm, but the interiors of the cornified cells were sufficiently well keratinized to prevent mare than slight enzymatic cytolysis of the normal cell components. Characteristically large, weakly stainable, non-shrunken nuclear remnants were found in the salamander and frog horny layers, but the clawed toad had small pyknotic (parakeratotic) nuclei. The mature amphibian keratinocytes contained free fats, bound phospholipids, calcium and sulphydryl groups, together with acid phosphatase and non-specific esterase. Cornification appears to begin by a process of separate individual cell keratinization and lateral membranes of neighbouring cells only later become fused together. This differs from the process in higher vertebrates in which the cells undergoing keratinization form a uniform transitional layer in the epidermis. In the amphibian epidermis neighbouring cells occur in different stages of keratinization.

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MOULTING IN THE ANURA: THE NORMAL MOULTING CYCLE OF BUFO REGULARIS REUSS

Cited by 11 publications

References 16 publications

Changes in cutaneous microbial abundance with sloughing: possible implications for infection and disease in amphibians

Changes in cutaneous microbial abundance with sloughing: possible implications for infection and disease in amphibians

Interactions between amphibian skin sloughing and a cutaneous fungal disease: infection progression, immune defence, and phylogenetic patterns

Epidermal keratinization in the salamander and a comparison with other amphibia

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