Ultrastructure and wear patterns of the ventral epidermis of four snake species (Squamata, Serpentes)

Klein, Marie-Christin G.; Gorb, Stanislav N.

doi:10.1016/j.zool.2014.01.004

Cited by 28 publications

(20 citation statements)

References 35 publications

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“…A cysteine-rich keratin component of reptilian claws has been lost due to gene inactivation during the evolution of snakes28. The presence of various ultrastructurally, but not biochemically, defined epidermal components such as fibers in the beta-layer29 and different granules in the oberhautchen and the clear layer of reptiles21 indicate that many structural proteins of snake epidermis remain to be identified.…”

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confidence: 99%

Identification and comparative analysis of the epidermal differentiation complex in snakes

Holthaus

Mlitz

Strasser

et al. 2017

Sci Rep

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The epidermis of snakes efficiently protects against dehydration and mechanical stress. However, only few proteins of the epidermal barrier to the environment have so far been identified in snakes. Here, we determined the organization of the Epidermal Differentiation Complex (EDC), a cluster of genes encoding protein constituents of cornified epidermal structures, in snakes and compared it to the EDCs of other squamates and non-squamate reptiles. The EDC of snakes displays shared synteny with that of the green anole lizard, including the presence of a cluster of corneous beta-protein (CBP)/beta-keratin genes. We found that a unique CBP comprising 4 putative beta-sheets and multiple cysteine-rich EDC proteins are conserved in all snakes and other squamates investigated. Comparative genomics of squamates suggests that the evolution of snakes was associated with a gene duplication generating two isoforms of the S100 fused-type protein, scaffoldin, the origin of distinct snake-specific EDC genes, and the loss of other genes that were present in the EDC of the last common ancestor of snakes and lizards. Taken together, our results provide new insights into the evolution of the skin in squamates and a basis for the characterization of the molecular composition of the epidermis in snakes.

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confidence: 99%

Identification and comparative analysis of the epidermal differentiation complex in snakes

Holthaus

Mlitz

Strasser

et al. 2017

Sci Rep

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“…Previous measurement of the frictional properties of dorsal and ventral scales from other species report large differences between the ventral and dorsal scales [4,5,55,56]. Ventral scales possess a lower friction coefficient compared with dorsal scales [5,35]. This reduction of friction at the ventral surface could be a direct result of the observed well-ordered lipid monolayer acting as a lubricating layer [57].…”

Section: Resultsmentioning

confidence: 94%

Evidence of a molecular boundary lubricant at snakeskin surfaces

Baio

Spinner

Jaye

et al. 2015

J. R. Soc. Interface.

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During slithering locomotion the ventral scales at a snake's belly are in direct mechanical interaction with the environment, while the dorsal scales provide optical camouflage and thermoregulation. Recent work has demonstrated that compared to dorsal scales, ventral scales provide improved lubrication and wear protection. While biomechanic adaption of snake motion is of growing interest in the fields of material science and robotics, the mechanism for how ventral scales influence the friction between the snake and substrate, at the molecular level, is unknown. In this study, we characterize the outermost surface of snake scales using sum frequency generation (SFG) spectra and near-edge X-ray absorption fine structure (NEXAFS) images collected from recently shed California kingsnake (Lampropeltis californiae) epidermis. SFG's nonlinear optical selection rules provide information about the outermost surface of materials; NEXAFS takes advantage of the shallow escape depth of the electrons to probe the molecular structure of surfaces. Our analysis of the data revealed the existence of a previously unknown lipid coating on both the ventral and dorsal scales. Additionally, the molecular structure of this lipid coating closely aligns to the biological function: lipids on ventral scales form a highly ordered layer which provides both lubrication and wear protection at the snake's ventral surface.

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“…Of the existing studies, only few animal skin have been investigated (e.g. few reptiles, porcine and rat [35][36][37][38][39][40][41][42]). Cross correlation of human skin performance to performance of other skin types is a very active topic within transdermal drug delivery.…”

Section: Sqmentioning

confidence: 99%

“…A schematic drawing of the layered structure of human skin. The figure depicts both a projection view and a skin cross-sectional isometric view of the various skin layersThe exuvium surface geometry of shed snake epidermis does not differ from that of a live animal[42,66,67]. Therefore, the shed skin of snakes reflects the frictional response of the live animal.…”

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confidence: 99%

A comparative study of frictional response of shed snakeskin and human skin

Abdel-Aal

Mansori

Zahouani

2017

Wear

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Skin in biological systems, including humans, perform several synchronized tasks (mechanical, protective, tactile, sensory, etc.). Tribological function is among skin tasks and may determine the survivability of many species. Cross comparison of tribological functional traits of skin of different species, albeit interesting, is rarely encountered, if at all exists, in tribology literature. One interesting example is that of snake and human skins. This skin pair was the subject of many studies for transdermal drug delivery. Results in that context concluded that snakeskin is highly compatible with human skin despite apparent differences in surface structure and topology. The reported compatibility raises curious question of whether there exists frictional or tribological compatibility between the two skins and if so, under what conditions, and which context. In this work, we report, for the first time in open literature, results of a comprehensive comparative investigation of shed snakeskin and human skin with respect to tribological behaviour. To this end, we compared the frictional response of shed skin obtained from P. regius and human skin from different anatomical sites, gender, and age. The results imply that, in essence, the mechanisms governing the friction response of human skin are common to snake skin despite difference in chemical composition and apparent surface structure. In particular, both skin types display sensitivity to hysteresis and adhesive dissipation. Human skin, however, being more sensitive to hysteresis than snakeskin. One interesting finding of the study is that the ratio of the coefficients of friction for snake and human skin, when sliding on the same interface, depends on the reciprocal of their respective moduli of elasticity.

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Ultrastructure and wear patterns of the ventral epidermis of four snake species (Squamata, Serpentes)

Cited by 28 publications

References 35 publications

Identification and comparative analysis of the epidermal differentiation complex in snakes

Identification and comparative analysis of the epidermal differentiation complex in snakes

Evidence of a molecular boundary lubricant at snakeskin surfaces

A comparative study of frictional response of shed snakeskin and human skin

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