APR 02, 2018 5:06 PM PDT

Cracking the Eggshell's Structural Mysteries

WRITTEN BY: Carmen Leitch

Eggshells are a marvel of nature; they can resist breakage by outside forces, yet will easily crack open from the inside as a chick hatches. Scientists at McGill University have learned that the trick lies in the nanostructure of the eggshell. The perfect shell has evolved over millions of years, now this new work, reported in Science Advances, could help improve food safety.

Living tissue can make minerals, and subsequently stiffen up, in a process called biomineralization; eggshells are a biomineralized chamber that holds nutrients and protects chick embryos as they develop. Researchers wanted to know where these unique characteristics came from and utilized new procedures in sample preparation to analyze the eggshell’s interior. They wanted to get a look at the mechanical properties and molecular features.

"Eggshells are notoriously difficult to study by traditional means because they easily break when we try to make a thin slice for imaging by electron microscopy," explained McKee, a professor in McGill's Department of Anatomy and Cell Biology. "Thanks to a new focused-ion beam sectioning system recently obtained by McGill's Facility for Electron Microscopy Research, we were able to accurately and thinly cut the sample and image the interior of the shell."

Minerals and many proteins make up eggshells, including osteopontin, a protein also found in bone. The first author of this work, graduate student Dimitra Athanasiadou, found that a critical component of shell strength is a nanostructured mineral that is associated with osteopontin. 

Over their short lifetimes though, bird eggshells change their strength. For example, they get thinner and weaker before hatching begins. Now, researchers investigating eggshell structure have zeroed in on the fine structure and mechanical properties of chicken eggshells, and shell changes associated with chick hatching. / Credit: Carla Schaffer/ AAAS

The investigators also learned more about chick development during their study. A growing chick needs calcium to make bones; the interior of the eggshell dissolves as the chick develops, providing it with a supply of minerals. That process also weakens the structure of the shell, so that it can eventually be broken open by the chick.
 
The scientists and collaborators then used a variety of imaging methods to investigate that reciprocal relationship. Atomic force microscopy, X-ray and electron analysis techniques showed that tiny changes in the nanostructure of the shell make this process possible during the incubation of an egg.

Additional work indicated that a nanostructure similar to what they found could be recreated in the lab by adding osteopontin to growing mineral crystals.

Professor McKee suggested that a better understanding of how proteins function in calcification events that promote the hardening and strengthening of eggshells through biomineralization may have critical implications for food safety.

Eggshells have the integrity to protect a developing chick, but will crack when it's ready. / Image credit: Pixabay

"About ten to twenty percent of chicken eggs break or crack, which increases the risk of Salmonella poisoning," said McKee. "Understanding how mineral nanostructure contributes to shell strength will allow for selection of genetic traits in laying hens to produce consistently stronger eggs for enhanced food safety."


Sources: AAAS/Eurekalert! via McGill University, Science Advances

About the Author
BS
Experienced research scientist and technical expert with authorships on over 30 peer-reviewed publications, traveler to over 70 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
AUG 08, 2022
Genetics & Genomics
This Weed is a Super Plant, Providing Insight Into Drought Tolerance
AUG 08, 2022
This Weed is a Super Plant, Providing Insight Into Drought Tolerance
You may have seen a 'super plant' growing in between the cracks of sidewalks. Portulaca oleracea is commonly known as pu ...
AUG 15, 2022
Cell & Molecular Biology
Researchers Create the First Synthetic Mouse Embryo
AUG 15, 2022
Researchers Create the First Synthetic Mouse Embryo
Scientists have been able to create stem cells that can mimic the early stages of mouse development. The researchers use ...
AUG 24, 2022
Immunology
Immune Cells Can Use 'Waste' as a Powerful Fuel
AUG 24, 2022
Immune Cells Can Use 'Waste' as a Powerful Fuel
T cells are on the front lines of the immune system, monitoring the body for pathogens, and springing into action when t ...
SEP 27, 2022
Neuroscience
How the Lactate Receptor is Related to Brain Injury in Newborns
SEP 27, 2022
How the Lactate Receptor is Related to Brain Injury in Newborns
Hypoxic-ischemic brain injury, which occurs when the brain's supply of oxygen and blood is blocked for a period of time, ...
SEP 21, 2022
Plants & Animals
Mutation Correction Machinery from Moss Transplanted to Human Cells
SEP 21, 2022
Mutation Correction Machinery from Moss Transplanted to Human Cells
Protein creation is essential to the normal function of healthy cells. Proteins help communicate key information to vari ...
OCT 06, 2022
Chemistry & Physics
2022 Nobel Prize in Chemistry
OCT 06, 2022
2022 Nobel Prize in Chemistry
It’s that time of year again! Three scientists, Carolyn R. Bertozzi, Morten Meldal, and K. Barry Sharpless, were a ...
Loading Comments...