Functional connections between bird eggshell stiffness and nest characteristics through risk of egg collision in nests.

Eggs and nests are two critical traits for the ecological success of birds. Their functional interactions, however, remain unclear. Here, we examined the functional connections between egg stiffness and nest attachment, site and structure for 1350 avian species. We revealed high eggshell stiffness for eggs in nests with a pensile attachment, located on non-tree vegetation or having a domed shape, suggesting that birds produce stiffer eggs in response to higher egg-collision risk in unstable or enclosed nests. Interdependence models suggested that the evolution of eggshell stiffness was more likely to be driven by than drive that of nest characters. Our results implied a trade-off between investment in competing for established nesting niches and producing stiff eggs to explore novel niches with high collision risk, possibly mediated by predation or thermoregulation. This study highlights an overlooked connection between nests and eggshells that may have broadened the ecological niches of birds.

Elastic Moduli of Avian Eggshell.

We analyze 700 freshly-laid eggs from 58 species (22 families and 13 orders) across three orders of magnitude in egg mass. We study the elastic moduli using three metrics: (i) effective Young's modulus, EFEM, by a combined experimental and numerical method; (ii) elastic modulus, Enano, by nanoindentation, and (iii) theoretical Young's modulus, Etheory. We measure the mineral content by acid-base titration, and crystallographic characteristics by electron backscatter diffraction (EBSD), on representative species. We find that the mineral content ranges between 83.1% (Zebra finch) and 96.5% (ostrich) and is positively correlated with EFEM-23.28 GPa (Zebra finch) and 47.76 GPa (ostrich). The EBSD shows that eggshell is anisotropic and non-homogeneous, and different species have different degrees of crystal orientation and texture. Ostrich eggshell exhibits strong texture in the thickness direction, whereas chicken eggshell has little. Such anisotropy and inhomogeneity are consistent with the nanoindentation tests. However, the crystal characteristics do not appear to correlate with EFEM, as EFEM represents an overall "average" elasticity of the entire shell. The experimental results are consistent with the theoretical prediction of linear elasticity. Our comprehensive investigation into the elastic moduli of avian eggshell over broad taxonomic scales provides a useful dataset for those who work on avian reproduction.

The avian egg exhibits general allometric invariances in mechanical design.

The avian egg exhibits extraordinary diversity in size, shape and color, and has a key role in avian adaptive radiations. Despite extensive work, our understanding of the underlying principles that guide the "design" of the egg as a load-bearing structure remains incomplete, especially over broad taxonomic scales. Here we define a dimensionless number C, a function of egg weight, stiffness and dimensions, to quantify how stiff an egg is with respect to its weight after removing geometry-induced rigidity. We analyze eggs of 463 bird species in 36 orders across five orders of magnitude in body mass, and find that C number is nearly invariant for most species, including tiny hummingbirds and giant elephant birds. This invariance or "design guideline" dictates that evolutionary changes in shell thickness and Young's modulus, both contributing to shell stiffness, are constrained by changes in egg weight. Our analysis illuminates unique reproductive strategies of brood parasites, kiwis, and megapodes, and quantifies the loss of safety margin for contact incubation due to artificial selection and environmental toxins. Our approach provides a mechanistic framework for a better understanding of the mechanical design of the avian egg, and may provide clues to the evolutionary origin of contact incubation of amniote eggs.

[Plasma endothelin levels in patients with multiple organ dysfunction syndrome caused by fish gall bladder poisoning].

OBJECTIVE: To investigate the correlation between the change of plasma endothelin (ET) and the occurrence and progress of multiple organ dysfunction syndrome (MODS) caused by fish gall bladder poisoning. METHODS: Plasma ET was measured in 85 patients with fish gall bladder poisoning and 30 healthy controls and comparison of the levels of plasma ET was carried out between patients groups with different severity of fish gall bladder poisoning. The relationship between plasma ET levels and enzymology as well as some biochemistry indexes in patients with fish gall bladder poisoning was then analyzed. RESULTS: Plasma ET in patients with fish gall bladder poisoning (150.5 +/- 90.5) ng/L was much higher than that in controls (52.8 +/- 9.3) ng/L. The concentration of plasma ET in slight poisoning group (61.2 +/- 13.6) ng/L increased a little, but it was not significantly different with that in controls (P > 0.05). The concentration of plasma ET was significantly higher in moderate poisoning group and severe poisoning group (162.3 +/- 82.3) ng/L and (232.6 +/- 92.7) ng/L as compared with that in the controls (P < 0.01), with the severe poisoning group much higher than the moderate poisoning group and the latter much higher than the normal. At the same time, plasma ET in MODS group and non-MODS group (210.2 +/- 98.7) ng/L and (126.3 +/- 68.3) ng/L were both notably higher than that in the controls. Furthermore plasma ET in the MODS group was much higher than that in the non-MODS (P < 0.01). It was also found that a positive correlation existed between plasma ET and creatine kinase-MB, cardiac troponin I, lactate dehydrogenase, alanine aminotransferase, aspartate aminotransferase, blood urea nitrogen and serum creatinine (P < 0.01) and a negative correlation between plasma ET and endogenous creatinine clearance rate (P < 0.01). CONCLUSION: Plasma ET may be involved in the process of fish gall ladder poisoning and later in the progress of MODS. It was shown that the higher the level of plasma ET, the severer the degree of poisoning and the higher the fatality rate. So monitoring plasma ET level dynamically may be an important clinical index in judging the patients condition and their prognosis in fish gall bladder poisoning. Simultaneously it is useful for earlier diagnosis of fish gall bladder poisoning and alertness of MODS caused by it as well as for proper management with antagonist and inhibitor against plasma ET for prevention and cure of fish gall bladder poisoning.