Antimicrobial properties of a nanostructured eggshell from a compost-nesting bird

D’Alba, Liliana; Jones, Darryl; Badawy, Hope T.; Eliason, Chad M.; Shawkey, Matthew D.

doi:10.1242/jeb.098343

Cited by 54 publications

(56 citation statements)

References 58 publications

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“…() in L. ocellata and D'Alba et al . () in A. lathami , has antimicrobial properties that prevent infection of the developing embryo in the wet nesting environment (D'Alba et al ., ). Although, accessory layers are not rare in avian eggs, the clade Podicipedidae+Phoenicopteridae (Tullett et al ., ; Board et al ., ), in addition to the Guinea fowl (Board et al ., ), possess the same chemical and crystallographic accessory layer as L. ocellata .…”

Section: Discussionmentioning

confidence: 99%

The biomechanical, chemical and physiological adaptations of the eggs of two Australian megapodes to their nesting strategies and their implications for extinct titanosaur dinosaurs

Grellet-Tinner

Lindsay

Thompson

2017

Journal of Microscopy

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Megapodes are galliform birds endemic to Australasia and unusual among modern birds in that they bury their eggs for incubation in diverse substrates and using various strategies. Alectura lathami and Leipoa ocellata are Australian megapodes that build and nest in mounds of soil and organic matter. Such unusual nesting behaviours have resulted in particular evolutionary adaptations of their eggs and eggshells. We used a combination of scanning electron microscopy, including electron backscatter diffraction and energy-dispersive X-ray spectroscopy, to determine the fine structure of the eggshells and micro-CT scanning to map the structure of pores. We discovered that the surface of the eggshell of A. lathami displays nodes similar to those of extinct titanosaur dinosaurs from Transylvania and Auca Mahuevo egg layer #4. We propose that this pronounced nodular ornamentation is an adaptation to an environment rich in organic acids from their nest mound, protecting the egg surface from chemical etching and leaving the eggshell thickness intact. By contrast, L. ocellata nests in mounds of sand with less organic matter in semiarid environments and has eggshells with weakly defined nodes, like those of extinct titanosaurs from AM L#3 that also lived in a semiarid environment. We suggest the internode spaces in both megapode and titanosaur species act as funnels, which concentrate the condensed water vapour between the nodes. This water funnelling in megapodes through the layer of calcium phosphate reduces the likelihood of bacterial infection by creating a barrier to microbial invasion. In addition, the accessory layer of both species possesses sulphur, which reinforces the calcium phosphate barrier to bacterial and fungal contamination. Like titanosaurs, pores through the eggshell are Y-shaped in both species, but A. lathami displays unique mid-shell connections tangential to the eggshell surface and that connect some adjacent pores, like the eggshells of titanosaur of AM L#4 and Transylvania. The function of these interconnections is not known, but likely helps the diffusion of gases in eggs buried in environments where occlusion of pores is possible.

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Section: Discussionmentioning

confidence: 99%

The biomechanical, chemical and physiological adaptations of the eggs of two Australian megapodes to their nesting strategies and their implications for extinct titanosaur dinosaurs

Grellet-Tinner

Lindsay

Thompson

2017

Journal of Microscopy

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“…The inorganic component of avian eggshells is largely composed of calcite, but calcium phosphates have also been reported in eggshells of a number of species [31,35,52 -54]. In brush turkey eggs (Alectura lathami), phosphate is associated with approximately 300 nm spheres that produce a rough surface [35], whereas in chicken eggs, phosphate is associated with needle-like hydroxyapatite crystals that form spherical patterns in the cuticle [31]. Calcium phosphate is thus associated with both rough and smooth surfaces, suggesting that it may contribute to surface modification in entirely opposing ways.…”

Section: Discussionmentioning

confidence: 99%

A nanostructural basis for gloss of avian eggshells

Igic

Fecheyr-Lippens

Xiao

et al. 2015

J. R. Soc. Interface.

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The role of pigments in generating the colour and maculation of birds' eggs is well characterized, whereas the effects of the eggshell's nanostructure on the visual appearance of eggs are little studied. Here, we examined the nanostructural basis of glossiness of tinamou eggs. Tinamou eggs are well known for their glossy appearance, but the underlying mechanism responsible for this optical effect is unclear. Using experimental manipulations in conjunction with angle-resolved spectrophotometry, scanning electron microscopy, atomic force microscopy and chemical analyses, we show that the glossy appearance of tinamou eggshells is produced by an extremely smooth cuticle, composed of calcium carbonate, calcium phosphate and, potentially, organic compounds such as proteins and pigments. Optical calculations corroborate surface smoothness as the main factor producing gloss. Furthermore, we reveal the presence of weak iridescence on eggs of the great tinamou (Tinamus major), an optical effect never previously documented for bird eggs. These data highlight the need for further exploration into the nanostructural mechanisms for the production of colour and other optical effects of avian eggshells.

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“…In support of this hypothesis, D'Alba et al . () found that cuticular nanospheres of hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 ) had a hydrophobic effect, reducing the likelihood of bacterial attachment on the eggshells of the Australian Brushturkey Alectura lathami . Furthermore, a subsequent study found that cuticular nanospheres occur most commonly on the eggs of species that nest in warm, humid environments, suggesting an antimicrobial function (D'Alba et al .…”

Section: Discussionmentioning

confidence: 99%

A rare mineral, vaterite, acts as a shock absorber in the eggshell of a communally nesting bird

Portugal

Bowen

Riehl

2017

Ibis

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Birds' eggshells are primarily composed of calcite, an abundant polymorph of calcium carbonate (CaCO 3 ). However, the eggshells of some species are coated with spherules of vaterite, a rare and thermodynamically unstable polymorph of CaCO 3 , the function of which remains unknown. We experimentally tested the mechanical and physiological effects of the vaterite coating on eggshells of the Greater Ani Crotophaga major, a tropical cuckoo. Vaterite removal did not affect vapour conductance rates across the eggshell, indicating that the vaterite coating does not influence gas exchange during embryonic development. However, nanoindentation revealed that the hardness and elasticity of vaterite is similar to that of calcite, and white light interferometry showed that the vaterite layer increased the total thickness of the shell cuticle by up to 10%. Furthermore, calculations of contact mechanics found that when two eggs come into contact, the depth of the surface deformation caused by the contact is far less than the thickness of the vaterite coating. These results suggest that the layer of vaterite spherules may act as a shock absorber for the underlying calcite shell, protecting it from mechanical damage caused by collision with other eggs in the nest and reducing the risk of eggshell fracture during incubation.

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Antimicrobial properties of a nanostructured eggshell from a compost-nesting bird

Cited by 54 publications

References 58 publications

The biomechanical, chemical and physiological adaptations of the eggs of two Australian megapodes to their nesting strategies and their implications for extinct titanosaur dinosaurs

The biomechanical, chemical and physiological adaptations of the eggs of two Australian megapodes to their nesting strategies and their implications for extinct titanosaur dinosaurs

A nanostructural basis for gloss of avian eggshells

A rare mineral, vaterite, acts as a shock absorber in the eggshell of a communally nesting bird

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