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How to tell if eggs are bad — according to science

Every once in a while, you come across an egg and you’re not exactly sure if it’s still good anymore. Maybe it smells a bit funny, maybe it’s past its due date, or it’s just been in the fridge for a few days and you wanna be sure. But due dates can be misleading, and smell alone is not a reliable indicator. So how can you tell if the eggs are still good?

We’ve looked at some of the methods and found what really works.

Why it matters

Every year, the average person on the globe consumes 197 eggs. In many countries (like the US) that figure is much higher, at almost 300 per year. But many eggs are also thrown away. In the UK alone, 720 million eggs are wasted every year and worldwide, and while global estimates are scarce, wasted eggs probably number in the billions every year.

Granted, some of this waste happens due to restaurants or producers, but consumers can also play their part and not throw away eggs unless they have gone bad. At the same time, you really don’t want to consume bad eggs, as this would increase the risk of Salmonella or E. coli infection — which can cause diarrhea, fever, and vomiting.

To reduce the risk of bacterial infection from eggs, you can keep eggs refrigerated (which keeps them fresh for a longer time), and cook them thoroughly. A 2011 research project has found that keeping eggs at steady, low temperatures can help their natural defenses against bacteria.

Generally speaking, you shouldn’t eat eggs past their expiration date. However, some eggs have sell-by dates, others have eat-by (or expiration dates), which can get confusing. Also, those dates aren’t absolute. Most health and food organizations note that eggs are usually good for several weeks past the stamped date, but they can also get bad quicker, if stored improperly.

This is why it’s important to have a reliable method to check if your eggs are still good.

How to tell if eggs are bad: the floating test

The most common (and probably most reliable) test to check if an egg is bad is the floating test. You take a glass (or a pot, or any container really), and fill it with room temperature water. Place your egg (or eggs, just one at a time) in the water. If the egg floats, it’s not good anymore — simple as that.

Good eggs are heavier than water, which is why they sink. But when an egg starts to decompose, it becomes lighter by giving off gases. This creates pockets of air, especially at the bottom of the egg. But if the egg was a perfectly isolated system, it wouldn’t float. After all, even when solid or liquid mass changes into gas, it has the same mass.

This common method is not a myth, it actually works, and there’s some interesting science as to why it does.

Why it works

There’s a common misconception about the egg float test. The reason why bad eggs float has to do with pockets of air forming, but that’s only half of the story.

Good eggs are heavier than water, which is why they sink. But when an egg starts to decompose, it becomes lighter. When an egg starts to decompose, it gives off gases. This creates pockets of air, especially at the bottom of the egg. But if the egg was a perfectly isolated system, it wouldn’t float. After all, even when solid or liquid mass changes into gas, it has the same mass.

However, eggs aren’t perfectly isolated, they have pores and gases can escape. These gases, light as they may be, still have mass, and when they escape, they make the egg lighter. At some point, when the egg becomes lighter than water, it floats — and it’s not good for consumption anymore. This is probably the best test to employ to see if eggs are still good.

The shake test

A less reliable but still useful test is to take an egg and shake it gently by your ear. Listen carefully; is there a sloshing sound and feel? If not, you’ve probably got a fresh egg. If you do hear it, you may be dealing with an egg that has gone bad.

Keep in mind that if you shake them hard enough, even fresh eggs can make a sloshing sound, so shake them gently.

Why it works

As an egg gets older, the yolk becomes more alkaline and runny. It’s hard to say exactly where exactly the point of no return is, but as a rule of thumb, if the yolk seems too runny, it’s a bad egg.

There’s a bit of art to this test, and it’s best to complement it with another.

The good old smell test

A good cracked egg.

We’ve mentioned before that smell alone is not a reliable indicator — and it’s not. But if you crack an egg and it just smells bad, you should throw it away (they don’t call them rotten eggs for nothing). There’s a good chance the egg may actually be bad, but even if it’s not, you probably won’t be able to enjoy it, so better not to take any risks.

Why it works

The smell from bad eggs is a mixture of things, but a key component is hydrogen sulfide (H2S) — a heavy and pungent gas. If you feel any sulfur-type smell coming from the eggs, that’s a sign of decomposition.

Fresh eggs don’t emit a smell, but keep in mind that eggs can “suck” up smells from your fridge (which is why you should keep them covered and in a carton that can absorb any unwanted smells).

The visual test

If you crack open an egg and you see a discolored yolk, it’s likely bad. The same thing goes for eggs with white parts that are cloudy. But if you’ve reached that point, the odds are the egg is stinky already.

Why it works

It’s not just decomposition and bacteria, there’s also some chemistry that changes the color (and smell) of the eggs. Eggs contain carbonic acid — an acid that forms when carbon dioxide reacts with water. Carbonic acid slowly turns into CO2 (and other gases), and leaves the egg; this is why the floating egg test works. But at the same time, this makes the remaining egg more alkaline, and more chemically capable of interacting with hydrogen.

This changing chemistry is a big part of why the inside of the egg looks different, and also a big part of why it smells differently.

The “not sure” test

Are you unsure if an egg is safe to eat? Just don’t eat it — that’s the “not sure” test.

We all want to play our part and fight food waste, and that’s a very noble goal. But if you’ve done the test and still have doubts about it, it’s best to just play it safe and not take any risks.

Egg tips

Boiling eggs and then storing them in the fridge for a few days can be useful for salads, sandwiches, etc.

Always cook eggs properly. Cooking isn’t just something we do to make food edible or tastier, it’s also something we do to kill off pathogens.

If you’ve got eggs and want to cook them but not consume them right away, the best thing to do is boil them. Boiled eggs don’t last as long as fresh eggs in the fridge, but hard-boiling eggs is a good way of giving them a couple of extra days. Boiled eggs can last up to a week when stored in the fridge, so if you’ve got a bunch of eggs you need to eat in a few days, you can use this for dressing or sandwiches or whatever else you like.

To give your eggs the most fridge life, store them in the coldest part of the fridge where they won’t freeze. It’s common to store eggs on the door, but that’s actually the least cold part of the fridge. Go deep and put them where it’s cold.

If you take eggs out, either put them back in quickly or cook them. When you take cold eggs out of the fridge, they “sweat” as the water condenses, creating an environment well-suited for bacterial growth. Avoid leaving eggs out for more than an hour, and if you do, it’s safest to cook them.

You can also freeze eggs (after cracking them), but if you don’t know what you’re doing, it’s best to avoid this.

As mentioned, leave eggs in their original carton. If you don’t have one, store them in something covered. Eggs can absorb smells and pick up unpleasant odors from your fridge.

Some countries (most notably in Western Europe) don’t store supermarket eggs in the fridge — but the fridge is still the best place to store them at home.

Some sperm cells swim faster and even poison their competition to climb to the top

It takes just one sperm to fertilize a woman’s egg and for each sperm that reaches the egg, there are millions that don’t. You probably knew that already, but here’s the thing: not all sperm cells are equal. Some have mutations in their DNA sequence that allow them to swim straighter, rather than in circles, and faster on average than their competition. What’s more, sperm cells can even employ gruesome tactics, such as poisoning their neighbors in order to enhance their odds of fertilizing the egg.

It’s not just about luck

 T-sperm outcompete their normal peers (+) in the race for the egg cell with genetic tricks, letting them swim in circles. Credit:  MPI f. Molecular Genetics/ Alexandra Amaral.

The difference between a ‘loser’ and a ‘winner’ sperm cell could be down to a protein: RAC1. In a new study, researchers at the Max Planck Institute for Molecular Genetics (MPIMG) in Germany studied mouse sperm cells under the microscope, finding that this protein is responsible for guiding the sperm in the right direction by chemically signaling from the outside and activating other proteins.

The RAC1 protein plays a critical role in controlling the motility of sperm, in particular the average path velocity and linearity. This protein is produced in sperm that carry a particular DNA sequence known as the t-haplotype.

The researchers in Germany knew from previous research that it is thanks to this genetic sequence that some sperm swim in a straighter path and at a faster velocity than sperm lacking the t-haplotype. However, they were shocked to learn that t-haplotype sperm can also ‘poison’ their competition by injecting them with certain genes that inhibit movement.

“Sperm with the t-haplotype manage to disable sperm without it,” study co-author Bernhard Herrmann, director at the MPIMG, said in a statement. “The trick is that the t‑haplotype ‘poisons’ all sperm, but at the same time produces an antidote, which acts only in t-sperm [those with the t-haplotype] and protects them.”

In other words, it literally is a race for life (or death) for the millions of sperm cells on a quest to fertilize egg cells — and luck seems to play a minor role.

“Imagine a marathon, in which all participants get poisoned drinking water, but some runners also take an antidote,” said Herrmann, who is also the director of the Institute of Medical Genetics at Charité – Universitätsmedizin Berlin. That’s the same hospital where Kremlin critic and Russian opposition leader Alexei Navalny was treated after being poisoned, allegedly by the Russian government.

According to experiments, the vast majority of sperm cells that made little progress on their paths were genetically “normal”, whereas those that moved in a straight and optimal path mostly had the t-haplotype genetic factor. Poisoned cells literally swam in circles until they died. Meanwhile,  t-haplotype sperm that had the antidote that inhibited the effects of the “poison” charge straight ahead.

“Our data highlight the fact that sperm cells are ruthless competitors,” says Herrmann. “Genetic differences can give individual sperm an advantage in the race for life, thus promoting the transmission of particular gene variants to the next generation,” says the scientist.

The findings were reported in the journal PLOS Genetics.

The earliest dinosaurs probably laid soft-shelled eggs

The first dinosaurs were huge softies, judging by the shells of the eggs they laid, a new study reports.

Photographs, histology and Raman spectroscopy of Protoceratops
and Mussaurus soft eggshells.
Image credits Mark A. Norell et al., (2020), Nature.

Researchers from the American Museum of Natural History and Yale University analyzed the eggs of two different non-avian dinosaurs to find that they resemble those of turtles in terms of microstructure, composition, and mechanical properties.

Meaning that early dinosaurs likely laid soft-shelled eggs. Under pressure from predators or the environment, dinosaurs evolved hard-shelled eggs at least three independent times, the team adds.

Getting an egg up

“The assumption has always been that the ancestral dinosaur egg was hard-shelled,” said lead author Mark Norell, chair and Macaulay Curator in the Museum’s Division of Paleontology. “Over the last 20 years, we’ve found dinosaur eggs around the world. But for the most part, they only represent three groups — theropod dinosaurs, advanced hadrosaurs like the duck-bill dinosaurs, and advanced sauropods.”

“At the same time, we’ve found thousands of skeletal remains of ceratopsian dinosaurs, but almost none of their eggs. So why weren’t their eggs preserved? My guess — and what we ended up proving through this study — is that they were soft-shelled.”

Amniotes are a group of animals including birds, mammals, and reptiles, which reproduce by laying eggs with an inner membrane or “amnion”. This membrane helps keep the embryo from drying out. Some amniotes, the team explains, including many turtles, lizards, and snakes, lay soft-shelled eggs, whereas others (mostly birds) lay hard-shelled eggs. Their hardness comes from high levels of calcification in the shell.

Harder eggshells provide better protection from the environment and was a big development for amniotes, as it allowed for more eggs to survive until hatching in more varied environments.

Modern crocodilians and birds, the closest living relatives to the dinosaurs, lay hard-shelled eggs. The fact that soft-shelled eggs rarely fossilize also helped as it made it extremely difficult to study the transition from soft to hard eggshells. So, it was assumed that non-avian dinosaurs used this type of shell.

But this was not the case, a new study reports. The authors studied embryo-containing fossil eggs of Protoceratops (a sheep-sized herbivore) and Mussaurus (a long-necked, big herbivore dino).

The skeletons of six among the Protoceratops embryos have been preserved surrounded by a black-and-white, egg-shaped halo, according to the team. Two of them (potentially hatched) were largely free of this halo. A closer analysis showed that the shapes were created from chemically-altered residues of the membrane lining the inside of all modern archosaur eggs. The same was true for the Mussaurus embryos.

Comparing the minerals that made up these shells with those in the eggshells of modern species, the team determined that the Protoceratops and Mussaurus eggs were indeed non-biomineralized, meaning they were leathery-soft.

“It’s an exceptional claim, so we need exceptional data,” said study author and Yale graduate student Jasmina Wiemann. “We had to come up with a brand-new proxy to be sure that what we were seeing was how the eggs were in life, and not just a result of some strange fossilization effect.”

“We now have a new method that can be applied to all other sorts of questions, as well as unambiguous evidence that complements the morphological and histological case for soft-shelled eggs in these animals.”

Using chemical composition data and the mechanical properties of eggshells from 112 other extinct and living relatives, the team determined that calcified eggs evolved independently at least three times in dinosaurs, probably from a soft-shelled type.

Soft eggshells are more sensitive to water loss and offer little protection against mechanical stress, so Protoceratops and Mussaurus probably buried them in sand or soil and incubated them with heat from decomposing plant matter, as some reptiles do today.

The paper “The first dinosaur egg was soft” has been published in the journal Nature.

Australian lizard is the first vertebrate seen to lay eggs and give birth in one pregnancy

Researchers at the University of Sydney report observing a three-toed skink (Saiphos equalis) lay eggs and give birth to live babies in the same litter. This is the first time a vertebrate has been witnessed doing so.

Image credits Bernard DUPONT / Flickr.

Three-toed skinks are one of the very few “bimodally reproductive” species we’ve ever found, animals in which some individuals lay eggs and others give birth to live offspring. But we’ve never seen one to do both. This world-first observation could help guide our research into the evolution of pregnancy.

Mixed approach

The lizard is native to the east coast of Australia. Individuals in the northern highlands of New South Wales typically birth live young, while those in and around Sydney lay eggs. Dr. Camilla Whittington at the University of Sydney reports on one of the lizards which lay three eggs and then weeks later give birth to a live baby from the same pregnancy.

“It is a very unusual discovery,” said Dr Camilla Whittington, from the School of Life and Environmental Sciences and Sydney School of Veterinary Science at the University of Sydney, the study’s lead author.

“We were studying the genetics of these skinks when we noticed one of the live-bearing females lay three eggs,” Dr Whittington said. “Several weeks later she gave birth to another baby. Seeing that baby was a very exciting moment!”

She quips that this finding makes the animal, which looks like a tiny snake with tinier legs, one of the “weirdest lizards in the world”.

Oh my god, that’s cute.
Image via Wikimedia.

The team published their observations along with advanced microscopy of the egg-coverings (shells). They explain that the first vertebrates laid eggs, and that some evolved over thousands of years to hold the young inside their bodies as they developed. Eventually, the length of time they did so became longer and led to them giving birth to live offspring.

Mammals are typically associated with this type of reproduction, but there are many modern reptile species that give birth, from turtles and lizards to snakes, crocodiles, and dinosaurs.

However, finding an individual that can both lay eggs and give birth is truly an incredible find. The team likens it to a snapshot in the process of evolution, allowing us to better understand it in action. The team hopes that more research on this animal can help us determine how major reproductive leaps take place in nature.

“Put in the context of evolutionary biology, being able to switch between laying eggs and giving live birth could allow animals to hedge their bets according to environmental conditions,” Dr Whittington adds.

The paper “Facultative oviparity in a viviparous skink (Saiphos equalis)” has been published in the journal Biology Letters.

Unhatched birds communicate with each other by vibrating shells

Developed but unhatched birds can not only pick up signals from their parents — they can also communicate with their (also unhatched) siblings by vibrating their shells.

Inside the eggs, gull embryos hear, and respond to, warning calls from adult gulls.

We humans are spoiled in many ways. We’re completely dependent on our parents for years, it takes us a long time to learn how to walk, and in most parts of the world, we rarely have to provide for ourselves. Other creatures don’t have these luxuries — they need to be prepared for danger as quickly as possible.

When danger lurks, most birds produce a distinctive warning sound. For gulls, it’s a specific “ha-ha-ha” sound. Chicks pick up on this signal and are alerted of the looming danger. But even before chicks are hatched, they can still pick up the danger.

A pair of researchers with Universidad de Vigo in Spain found that unhatched chicks can pick up the danger signal and vibrate their shells, transmitting the message to their less-developed siblings.

“We were very surprised,” said Jose Noguera, the lead author of the study from the Animal Ecology Group at the University of Vigo, Spain. “We were aware that bird embryos were able to produce egg vibrations, [but they vibrated] even more than we expected.”

This is not the first time embryonic communication has been studied. Previous research has shown that embryonic birds, amphibians, reptiles, and even insects receive sensory information that helps them prepare for the harsh realities of the real world. Being aware of these dangers and sharing this information with nestmates can help chicks adapt to real situations more quickly, boosting the family’s chances of survival.

The team also found that there are significant behavioral changes associated with this pre-hatching behavior.

In order to reach this conclusion, the team collected 90 yellow-legged gull eggs from Sálvora Island, a large breeding region off the coast of northern Spain. They sorted them into nests of three. Six days before hatching, two out of the three nest eggs were removed from the nest and then exposed to either a recording of a predator alarm or white noise. The third group was not exposed to any sounds.

The birds exposed to alarm calls vibrated in response. When they were reunited with the egg that was not exposed to any sounds, this egg also mimicked the vibrating sounds. The eggs also underwent genetic chances known to delay hatch time, as a response to looming danger, and had an increase in the production of stress hormones, which makes birds more aware of their surroundings after hatching. Birds that were exposed to alarm sounds were quicker to run and hide after hatching.

Researchers are still unsure how the embryos produce and understand these signals, but it’s an absolutely remarkable communication system, which may be much more widespread than it was previously realized.

The findings are published in the journal Nature Ecology and Evolution.

Eggs might not be that bad for you after all, new study finds

A new study finds that a consumption of up to one egg a day does not increase the risk of stroke.

Eating boiled eggs is substantially healthier than fried or scrambled.

Eggs are somewhat of an unsettled issue in modern nutrition: on the one hand, they have a wealth of valuable nutrients, but on the other hand, they also contain cholesterol and have been traditionally regarded as hazardous for cardiovascular health. Eggs have remained a controversial issue, with studies often finding contradictory results.

Now, a new effort finds that in low quantities (about 1 per day), eggs don’t seem to have any detrimental effect on the heart or blood pressure. In fact, there was a small inverse correlation between blood pressure and egg consumption.

The study analyzed the dietary habits of 1,950 Finnish men between 42 and 60 years old with no history of cardiovascular disease. The study also looked at carriers of a particular protein called E phenotype 4. This protein combines with fats (lipids) in the body to form molecules called lipoproteins. Lipoproteins are responsible for packaging cholesterol and other fats and delivering them through the bloodstream. People who carry this hereditary variant are particularly vulnerable to the effects of cholesterol. Finnish people are unusual in this regard: their prevalence of this variant is exceptionally high, affecting around 1 in 3 people. Presumably, if eating one egg a day would cause heart issues, you’d see it in this population first.

However, the study found that moderate egg consumption, even daily, does not seem to be associated with greater risk of stroke — even in people who are predisposed to the effects of cholesterol. While this is encouraging news for egg-lovers, it also shouldn’t be generalized: it all greatly depends on your total cholesterol intake (in this study, eggs represented an overall 25% of total cholesterol consumption). If your diet is rich in cholesterol and fats, then egg consumption can be the proverbial straw that breaks the camel’s back. Furthermore, the generalizability of this study is also weakened fact that the population in this study had no cardiovascular conditions or diseases, researchers say.

Nutrition is an amazingly complex topic, and eggs, in particular, are far from a settled issue. As it is so often the case, maintaining a balance is key. Overall, the research seems to indicate that, at least in a healthy diet, eggs can play a useful and important role. In other words, as long as you don’t eat too many saturated fats (butter, cheese, meats), you’ll probably be okay.

Journal Reference: Abdollahi et al. Egg consumption, cholesterol intake, and risk of incident stroke in men: the Kuopio Ischaemic Heart Disease Risk Factor Study. The American Journal of Clinical Nutrition, 2019; DOI:10.1093/ajcn/nqz066

Photograph of the holotype of Avimaia schweitzerae. Credit: Barbara Marrs.

Paleontologists find 110-million-year-old bird fossil with unlaid egg still inside it

Photograph of the holotype of Avimaia schweitzerae. Credit: Barbara Marrs.

Photograph of the holotype of Avimaia schweitzerae. Credit: Barbara Marrs.

A crushed, pancake-like fossil unearthed in northwestern China contains both a bird and its unlaid egg. The fossil also features a medullary bone — a special type of tissue which serves as a readily available store of calcium for the eggshell. This is the first time scientists have found such a bone and an egg together in the same fossil. Ironically, the authors say that the egg is what seems to have killed the mother.

Insight into the reproductive life of ancient birds

The new species, called Avimaia schweitzerae, belongs to a family of ancient birds known as Enantiornithes, which lived alongside their dinosaur cousins for more than 100 million years. Enantiornithine birds were widely distributed across the globe, with remains found in Argentina, North America, Mexico, Mongolia, Australia, Spain, and China. Paleontologists take a special interest in enantiornithines because the species includes both specialized and primitive features, suggesting they represent an evolutionary side branch of early avian evolution.

Paleontologists at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences found bits of eggshell preserved alongside the ancient bird’s fossilized skeleton. These eggshell fragments were detected inside the specimen’s abdomen, showing parts of the egg membrane and cuticle (a protein-covered outer layer that covers the surface of the egg and fills the pores that allow air inside for the growing chick). The researcher also detected small minerals made of calcium phosphate which are typically found among birds who bury their eggs. Previous evidence suggested that Enantiornithes buried their eggs, and these latest findings add more weight to this assumption.

At the same time, this particular eggshell features some unusual characteristics. The shell is too thin and it looks like it had two layers instead of one. This suggests that the mother bird went through egg-binding — when an egg takes longer than usual to pass out of the reproductive tract — and this may have been what ultimately killed her.

The analysis also showed that Avimaia schweitzerae had a reproductive tissue called the medullary bone, making it the only Mesozoic fossil featuring this kind of structure. Previously, scientists had argued that this tissue should to be present in other fossil birds, as well as dinosaurs and pterosaurs, but until now this identification proved ambiguous.

The findings appeared in the journal Nature Communications.

Dinosaurs laid colored eggs and passed this trait on to birds, new study shows

Not only were dinosaurs the masters of the land and the sea, but they were also the masters of color, a new study shows.

Speckled bird egg — but the dinosaurs did it first.

Lots of creatures lay eggs nowadays — reptiles, birds, and some fish — but only birds lay colored ones. Recently, the same pigments found in colored bird eggs have been discovered in some fossil dinosaur eggs. However, paleontologists weren’t sure if the birds inherited this trait from dinosaurs or developed it separately.

“The huge diversity of avian egg colour has previously been attributed to the exploration of empty ecological niches after the extinction of nonavian dinosaurs at the terminal Cretaceous event,” researchers write. “Different nesting environments, as well as nesting behaviours, are thought to influence egg colour. Egg colour may reflect selective pressure as a result of an ecological interaction between the egg producer and an egg predator (camouflage) or parasite (egg recognition).”

Jasmina Wiemann and colleagues from Yale University used spectroscopy to analyze a set of fossil eggshells, which included representatives of all major dinosaur groups, to look for evidence of pigmentation.

They found traces of pigments in the eggshells of all dinosaurs in the Maniraptora — a clade of small, bipedal, often feathered non-avian dinosaurs generally regarded as the ancestors of birds. The analysis revealed spotted and speckled patterns, deposited in a very similar fashion to what is observed in modern bird eggs.

Meanwhile, two more distant relatives of birds, called ornithischian and sauropod dinosaurs, were completely pigment free, indicating that these dinosaurs always had plain, colorless eggs. These two groups, which famously include Triceratops and Diplodocus had colorless eggs, the birds’ ancestors had colored eggs, birds have colored eggs — all this strongly suggest that pigmented eggs only evolved once, in bird-like therapods, and these pigments are carried through until the present day.

“The absence of colour in ornithischian and sauropod eggs represents a true signal,” researchers write.  They also describe “identical mechanisms of pigment deposition in nonavian and avian dinosaur eggs.”

Different nesting environments, as well as nesting behaviors, are thought to influence egg color. This still leaves us with a very straightforward question: why did colored eggs emerge in the first place?

“Egg colour may reflect selective pressure as a result of an ecological interaction between the egg producer and an egg predator (camouflage) or parasite (egg recognition),” the scientists continue. “Avian egg colour has previously been shown to react in a plastic fashion to changes in the incubation strategy or climate, or even in mating behaviour. However, all previously proposed selective factors rely on the fact that the eggs are exposed to the environment and, with scant exception, not buried or covered.”

Now, this study shows that if we want to truly understand egg coloration, we have to do so in the context of dinosaurs, not birds.

The study “Dinosaur egg colour had a single evolutionary origin” has been published in Nature.

Eggshells in Prof. McKee's lab. Credit: McGill University.

Scientists crack the eggshell nanostructure, finding what makes it so strong

Take a minute to marvel at the incredible complexity and resilience of a very familiar sight: the chicken egg. An egg’s shell is strong enough to not fracture from the outside, despite being quite thin, while at the same time being weak enough on the inside to allow a chick to hatch. What’s its secret? According to Canadian researchers at McGill University, it’s all in the eggshells nanostructure.

Eggshells in Prof. McKee's lab. Credit: McGill University.

Eggshells in Prof. McKee’s lab. Credit: McGill University.

In order to find out what makes a bird’s eggshell so unique, an interdisciplinary team comprised of dentistry researchers and engineers meticulously prepared eggshell samples, studying both their molecular nanostructure and mechanical properties. This was more challenging than it sounds. Because eggshells are so fragile, they easily break when you try to cut a slice for imaging by electron microscopy. The team solved this problem by using a focused-ion beam sectioning system to elegantly cut thin slices of eggshells and image their interior.

“Eggshells are remarkable in the world of biomineralization as they are one of the fastest know biomineralizing systems that we know of — a laying hen forms a 6-gram eggshell in about 17 hours almost every day. We were fascinated about how an eggshell could form so fast, and what its internal structure was like,” Marc McKee, a professor in McGill’s Department of Anatomy and Cell Biology and co-author of the new study, told ZME Science.

“We now have the research tools to cut very thin sections of the shells (a focused-ion beam that cuts just about anything), and this prevented the shell from shattering when we tried to cut it using previous methods.  With this very thin section, we were able to identify a fascinating subunit nanostructure within the interior of the shell using atomic force microscopy and electron microscopy. The ‘Aha’ moment was when we saw the nanostructure by various microscopies!  When had guessed it might be true because of the unique properties of the eggshell, but then we actually saw it, ‘Aha!’,” McKee added.

When a hen lays an egg, it is sufficiently hard not to break during brooding. As the embryo inside the egg develops, the inner portion of the shell dissolves to provide precious calcium, which the chick needs to grow bones. At the same time, this process weakens the shell enough for it to be broken by the hatching chick. McKee and colleagues learned that this dual-function is enabled by changes in the shell’s nanostructure during incubation. Specifically, the researchers singled out a nanostructured mineral associated with osteopontin — the eggshell protein also found in bones — as of the main factors driving shell strength. During an experiment, the researchers recreated a similar nanostructure in the lab by adding osteopontin to mineral crystals.

“Since we were able to reproduce something similar to the eggshell nanostructure in the laboratory setting by growing our own synthetic crystals in the presence of the eggshell protein osteopontin, this means that we can control nanostructure size of mineral in a protein matrix – thus making a nanocomposite biomaterial.  Nanocomposites, in general, are known for their strength and hardness, light weight and versatility and have many benefits and applications in many fields,” McKee said.

There are many potential applications to the findings. Understanding the role certain proteins play in the eggshell hardening process has important implications for food safety — cracked eggs have an increased risk of Salmonella poisoning, for instance. The findings could also open the door for a new class of eggshell-inspired composite materials that are both strong and lightweight.

“Because we could partly recreate eggshell structure in calcite mineral in the lab setting, this may allow us the ability to intentionally produce new nanocomposite materials with desirable properties.  Nanocomposites have amazing unique properties, and many new nanomaterials are being developed by many industries.  They are often strong and lightweight, amongst many other properties.  Of course, in the food industry, having a strong and tough eggshell will prevent cracks that allow pathogens access to the egg that might cause food poisoning.  Understanding more about shell nanostructure will allow us to select for strains of hens that consistently produce stronger eggs,” McKee told ZME.

In the future, researchers plan “to understand the mechanism of how the protein osteopontin controls the nanostructure and strength of the shell,” Mckee said.

“It is exciting because we are learning from Nature and 100s of millions of years of evolution how nanostructure provides optimal material properties for things as seemingly delicate as an avian eggshell.  In fact, the shell is remarkably strong and tough to serve its function, but also is finally delicate enough at a certain point in time to allow the chick to hatch from the egg by breaking the shell from the inside-out, all this results from nanostructure in general, and differences in nanostructure across the shell thickness.  As a biological nanocomposite, the interplay between a protein matrix and mineral provides unique and ideal properties for a shell structure that has persisted since the time of the dinosaurs,” the researcher concluded.

The findings were published in the journal Science Advances. 

How to boil the perfect egg, right to your taste, every time

Credit: Pixabay.

Boiling an egg doesn’t sound like the most challenging thing in the world. Just put a kettle on the stove, leave some eggs to boil for a couple minutes — presto! But if you’re after the perfectly boiled egg that is exactly to your taste, it’s going to take more diligence because eggs can be quite complex. Luckily, one quantum physicist has devised a calculator that tells you everything you need to do, based on pluggable parameters. With Easter right around the corner, you might want to give this a try.

The egg boiling calculator

There are many reasons why boiling an egg can go awry. For one, the yolk and white inside have different compositions of fats and proteins, which cook and harden at different temperatures and rates. This is why for a soft-boiled egg, you typically have to boil at a lower temperature and for a shorter while than for a hard-boiled egg. A smaller egg has a smaller surface area than a bigger egg, so it will cook faster — another thing you ought to consider.

An egg plucked straight from the fridge and into a kettle will boil differently than an egg that is stored at room temperature. Finally, altitude is very important as it affects the boiling point of water and, hence, the quality of your desired type of boiled egg. This latter parameter is also the most overlooked among the lot, despite having a significant impact. The higher up you climb relative to the sea level, the lower atmospheric pressure becomes. A liquid boils when its internal vapor pressure is equal to the atmospheric pressure, which is why the boiling point of water is lower at higher altitudes. In the city of El Alto, Bolivia (4,150 meters altitude), it takes two and half minutes longer to make a soft-boiled egg than at sea level. On Mt. Everest, the highest peak in the world, it’s impossible to boil an egg because the boiling point is too low for the proteins to get ‘cooked‘.

Miłosz Panfil, a theoretical physicist at the University of Warsaw, worked with Omni to devise an online calculator that takes all of these parameters into account and returns the optimal boiling time. The calculator is based on a formula devised almost twenty years ago by Charles Williams, a physicist at the University of Exeter. According to Science Alert, the simplified version looks like this:

t = m * K * log(ywr * (Tegg – Twater)/(T – Twater))

Where t stands for time, m is mass, K is the thermal conductivity of the egg, T is the temperature measured at a point between the white and yolk, Tegg is the egg temperature, Twater is the water temperature and ywr is the yolk-white ratio.

“We encountered typical issues with modeling natural phenomena: you have to make your ideas meet reality. Most of the work was done and perfectly explained by Charles Williams in his old paper. We had to tweak a bit some of the parameters, but with people working at OMNI this is not a challenge. Their enthusiasm for science made it a great adventure,” Panfil told ZME Science.

“I’m kind of excited to see if other people can follow our recipe and get a perfectly boiled egg,” Panfil added.

The maximum temperature you should set for a perfect soft- and hard-boiled egg is 65°C (149°F) and 77°C (170°F), respectively. If you’re using a gas burner to boil, you might find it difficult to maintain a constant temperature. A kitchen thermometer will save you a lot of headaches if you can’t control temperature.

Another parameter that might influence the quality of a boiled egg its source. The calculator, however, does not differentiate between eggs comes from free-range or caged hens, as this would have complicated matters even further.

“The type of hen’s diet likely influences the composition of an egg and there are claims the nutritional data varies for caged and free range eggs. That being said I would not expect a large difference. In home conditions, other factors are probably more important. However, I’m far from being an expert on the biochemistry of eggs so take it with a grain a salt,” according to Panfil, who said he likes his boiled eggs, “again, with a grain of salt. And a bit of pepper. I like them in their pure form. As I’m getting older my choice shifts from soft-boiled eggs to hard-boiled ones. My wife has a strong preference for soft-boiled eggs though. I guess it keeps me younger.”

Without further ado, here is the calculator.

[button url=”https://www.omnicalculator.com/other/eggs” postid=”” style=”btn-success” size=”btn-lg” target=”_self” fullwidth=”false”]Egg boiling calculator[/button]

egg spinning

Why a spinning hard-boiled egg always faces up

Sometimes, it takes a lot of time and dedication before a clever mind comes along and solves a long-standing mystery. Take the mind-boggling conundrum of the spinning hard-boiled egg that always stands upright as it continues to whirl around.

egg spinning

Credit: Giphy.

Physicists have come to learn that the spinning egg mainly rises due to the force of friction between the egg and the table. However, these explanations often employ complex equations and don’t capture the full picture. It was only recently that Rod Cross, a physicist at the University of Sydney, finally came up with a more elegant explanation.

Cross’ expertize is in plasma physics, but the retired Australian physicist is a sort of a local celebrity for his entertaining studies in Sports Mechanics, an interest that has led him to become a consultant to the police in murder investigations. On his website, you can find all sorts of video and explanations on everything from the physics of billiards and tennis balls to silly putty.

spinning egg

Credit: Ross Cross.

In a recent paper published in the European Journal of PhysicsCross showcased the findings of his experiments with a solid aluminum spheroid. The experiments showed that a spinning hard-boiled egg rotates, or precesses, about two different axes. One is the vertical axis, which is obvious as the egg spins. The other is the horizontal axis around which the egg rotates as it stands up on its end due to the horizontal friction force. When the egg starts rolling, the friction force drops to zero, stopping the egg’s motion.

“If an egg is on its fat end when it falls, it slides forward. On its pointy end, the egg rolls right over then slides. The egg has more potential energy when the fat end is at the top, so there is more kinetic energy when it falls. If the fat end remains at the bottom after falling, then the thin end can rotate all the way up to the top with enough energy left over to swing it past the top,” Cross wrote on his website. 

“Spun slowly clockwise, the egg precesses in a counter-clockwise direction,  rocking from one end to the other, in the same way that people move heavy furniture.”

Cross’ experiments also confirmed that the faster an egg spins, the more upright it stands. And if the egg isn’t spun with enough force, it won’t rise at all because friction causes the egg to roll instead of sliding and standing up. These characteristics are reminiscent of spinning coins and the inversion of a tippe top.

Rod Cross. Credit: Rod Cross.

Rod Cross. Credit: Rod Cross.

“Spinning eggs have been studied for more than 100 years, but there has not previously been a simple explanation for the rise, either of spinning eggs or the tippe top,” Cross told Phys.org. “The essential physics cannot be conveyed to an undergraduate student or to a physics teacher by explaining that an egg rises because the equations predict that it will rise.

“Part of the problem is that there have not been enough experimental measurements to pin down the separate roles of sliding and rolling friction in causing the egg (or tippe top) to rise and then causing it to stop rising if it is not spun fast enough.”

A 'black smoker' (left), the hottest type of vent. Skate egg cases collected in the area (right). Credit: Ocean Exploration Trust.

Deep-sea marine animals lay eggs near hydrothermal vents so they hatch faster

Deep-sea skates lay their eggs in the vicinity of hydrothermal vents to accelerate hatching, a surprising new study reveals. This is the first time that biologists have recorded such a behavior in marine animals.

A 'black smoker' (left), the hottest type of vent. Skate egg cases collected in the area (right). Credit: Ocean Exploration Trust.

A ‘black smoker’ (left), the hottest type of vent. Skate egg cases collected in the area (right). Credit: Ocean Exploration Trust.

The first time scientists suspected something like this was happening was in 2015 when they were surveying the seafloor northwest of the Galapagos Islands. The team, which was comprised of researchers at the University of Rhode Island and the Charles Darwin Research Station, was exploring the underwater mountains around the Galapagos when their remotely-operated submersible caught sight of something peculiar. Large numbers of egg cases of deep-sea skate, which are related to sharks and rays, were found littering the hot water around hydrothermal vents.

“We were on a really deep dive in a hydrothermally-active rift valley, with walls 30 meters tall on either side, and the ROV was meandering back and forth looking for vents,” said Brennan Phillips, an assistant professor of ocean engineering at the University of Rhode Island. “We started noticing all these egg cases, and we recorded their location and collected a few but then just kept going.”

Later, Phillips and colleagues analyzed the egg locations and found these coincided with known hydrothermal vent locations. A hydrothermal vent is a fissure in a planet’s surface from which geothermally heated water issues. Hydrothermal vents are commonly found near volcanically active places, areas where tectonic plates are moving apart at spreading centers, ocean basins, and hotspots.

The researchers hypothesize that the eggs are intentionally placed by the skates where the water is warmer than average in order to speed up hatching.

In total, 157 egg cases, each the size of an iPhone, were observed by the researchers. DNA analysis suggests these belonged to the Pacific white skate (Bathyraja spinosissima), which lives up to two thousand metres deep. Hence, not very much is known about this elusive creature.

Pacific White Skate. Credit: Wikimedia Commons.

Pacific White Skate. Credit: Wikimedia Commons.

About 58 percent of the egg cases were collected from within 20 meters of a black smoker, which is the hottest kind of hydrothermal vent, and 89 percent of all egg cases discovered by the group were laid in water that was hotter than the background temperature of 2.76 degrees Centigrade.

However, the eggs weren’t placed right next to the vents — temperatures there can exceed hundreds of degrees. Instead, most of the eggs were found in the lukewarm water not too far from the vents and near extinct vents, the authors wrote in Scientific Reports.

More skate egg cases. Credit: Ocean Exploration Trust.

More skate egg cases. Credit: Ocean Exploration Trust.

Phillips says that other marine animals likely do the same. When he showed the data to shark experts, they nodded their heads and said they had anecdotal evidence of shark and ray egg cases found near hydrothermal vents.

Non-marine animals take advantage of naturally warmer-than-average hot spots, as well. The Polynesian megapode (Megapodius pritchardii) nests in volcanically-heated soils, for instance. Even some dinosaurs likely did the same, judging from Cretaceous era sauropod fossils. 

Phillips believes that sharks, rays, skates, and possibly other animals — all of which evolved about 500 million years ago — have adapted to these unusual conditions and made the most of them.

“Seafloor volcanism comes and goes, and it is often one of the causes of mass extinctions,” he said. “It’s interesting to me that we’re seeing sharks and skates thriving around volcanoes and vent sites, like they’re especially resilient and have evolved to withstand the hot water environment.”


A lot of eggs in one basket: Paleontologists discover pterosaur egg bonanza

An extremely rare cache of over 200 eggs from pterosaurs from the Cretaceous era has been found by paleontologists in China. The finding, which researchers have described as “stellar” and “truly awesome” could allow researchers to understand the winged reptiles better than ever before.

Hundreds of pterosaur eggs and bones were found at the site. Image credits: Alexander Kellner/Museu Nacional/UFRJ.

Pterosaurs were flying reptiles which emerged during the Triassic period and lived until the Cretaceous. Although they weren’t related to the dinosaurs, they lived alongside them, shared certain similarities, and went extinct at about the same time as them. Along with bats and birds, pterosaurs are the only vertebrates to truly fly. While we’ve learned quite a bit about them from the fossil record, egg findings have been extremely scarce. Eggs are much more fragile than bones, and they require extremely specific conditions to properly fossilize. Up until now, only a handful of complete fossils have been recovered, and out of these, only six eggs are 3D — as in not flattened by millions of years of rock pressure.

The finding didn’t occur overnight. Researchers working in the Turpan-Hami Basin, in northwestern China, worked on uncovering the bones for ten years. The eggs were scattered around randomly and spanned a wide variety of sizes, indicating that this wasn’t a nest and that the eggs were probably laid by different animals, potentially from different species. It’s unclear how the eggs wound up together in such disarray; one possibility is that they were washed away together by a flood event. Unfortunately, this means that researchers don’t have access to important information, such as how many eggs female laid and how they were organized — but the sheer size of the discovery more than makes up for such shortcomings.

Example of fossilized pterosaur eggs. Credits: Alexander Kellner/Museu Nacional/UFRJ.

In total, paleontologists have discovered 215 eggs, with 16 of them containing embryonic remains of the pterosaur species Hamipterus tianshanensis. There may be even more of them, but scientists haven’t had time to properly analyze all the eggs, and CT scans are only partially useful.

“We want to find more eggs to make a much more detailed picture of embryonic development,” Alexander Kellner, a paleontologist with Laboratório de Sistemática e Tafonomia de Vertebrados Fósseis, told Newsweek. “So we are quite excited about that…. I’m quite certainly sure that there must be more embryos there.”

To make things even better, the fossil trove also includes skeletons from what appears to be all ages of pterosaur development — from hatchlings to adults. The discovery actually prompted the debate as to whether or not pterosaurs were capable of flying right after they were born. Since the hatchling fossils had much more developed hind legs than wings, this seems to indicate that the young were more inclined to walk around than fly.

“Thus, newborns were likely to move around but were not able to fly, leading to the hypothesis that Hamipterus might have been less precocious than advocated for flying reptiles in general … and probably needed some parental care,” the paper reads.

There’s still an ongoing debate about the validity of that theory, but one thing’s for sure: we’ve never had such a good view of how pterosaurs progressed from eggs to adulthood. It’s an embarrassment of riches, a once in a lifetime find.

“We learned a lot,” Kellner said. “For example, the bones associated with wings were less developed compared to the embryos development with their legs. So what we could learn from that? That most pterosaurs, when they hatched, they could walk, but they could not fly, so most likely they needed some parental care.”

H. tianshanensis was a giant flyer, with an estimated wingspan of 3.3 meters (11 feet). It had sharp teeth and a large crest running over its head, which probably made for quite a sight. It likely ate fish and lived in dry, sandy environments, where it buried its eggs on the shores of lakes and rivers (thus fitting with the idea of flowing water washing the eggs away). Pterosaurs were the first ever vertebrates to take to the skies — though why, how, and for how long they did this, remain unsolved mysteries. Even with such a rich find, the pterosaurs still manage to keep their secrets. But with paleontologists working more and more on the case, it only seems like only a matter of time now.

Journal Reference: Xiaolin Wang et al. Egg accumulation with 3D embryos provides insight into the life history of a pterosaur. DOI: 10.1126/science.aan2329.

This YouTube time-lapse of cellular division in action will have you hitting replay again and again

We’ve often talked about cellular multiplication or division, but have you actually ever seen it in action? Well, through the magic of modern technology and the cinematic flair of YouTuber francischeefilms, you’re about to have a front-row seat to the show.

Their time-lapse video shows a Rana temporaria / common frog tadpole egg on its journey from a humble four cells to several million, all in just 20 seconds.

That’s much faster than in real life. According to francischeefilms, the video took “about 33 hours at 15-17C approximately” to make.

“The whole microscope sits on anti-vibration table. [I]t doesn’t matter too much what microscope people use to perform this,” francischeefilms further explains on their YouTube page.

“There are countless other variables involved in performing this tricky shot, such as: the ambient temperature during shooting; the time at which the eggs were collected; the handling skills of the operator; the type of water used; lenses; quality of camera etc.”

The YouTuber had to design and put together his own equipment to capture these incredible shots, as well as get the lighting and microscope set-up exactly right.

But all that hard work certainly paid off — seeing a life just starting out with such enthusiasm is nothing short of amazing. So the next time division comes into discussion, you’ll know exactly what it looks like.


Scientists develop memory chips from egg shells

Eggshells might become the data storage of the future. A Chinese team showed that the material can be used to create greener RAM storage for out computers.

Image credits Steve Buissinne / Pixabay.

You’ve heard of eggplants, but what about eggcomputers? Seeking to bring the term about, a team from the Guizhou Institute of Technology hatched a cunning plan: they went to the market, bought a few random eggs, and ground their shells for three hours to make a homogeneous, nano-sized powder. After it was dry, the team mixed this powder into a solution and poured it onto a substrate.

They thus ended up with the part of a memory chip through which electricity actually flows — the electrolyte. But eggshells are not an item you tend to see in chip factories, so how could it function as RAM? Well, the team tested the egg-paste to see if it changes its electrical resistance when a voltage flows through it. This property can be used to create memory chips of the ReRAM, or resistive random access memory, variety. There’s a lot of interest in ReRAMas it could be used to create faster, denser, and more energy efficient storage media than traditional RAM or flash memory.

And it worked. The team was able to encode 100 bits of binary information into the eggmemory before it failed. It doesn’t stack up to the billions of cycles regular materials can take, but as a proof of concept it’s incredible.

It’s ground eggshell. That can store binary data.

Still, we’re a long way off from seeing one of these devices on the market. But if they do show promise for future applications and, with enough developement, could provide a clean, sustainable, and very egg-y alternative to the electrolytes in use today.

The full paper “A larger nonvolatile bipolar resistive switching memory behaviour fabricated using eggshells” have been published in the journal Current Applied Physics.

Mouse pups born from eggs released by lab-grown ovaries. Credit: O. Hikabe et. al.

Mouse eggs engineered entirely in the lab for the first time — later lead to healthy adults

Mouse pups born from eggs released by lab-grown ovaries. Credit: O. Hikabe et. al.

Mouse pups born from eggs released by lab-grown ovaries. Credit: O. Hikabe et. al.

A paper that has been met by everyone in the field with cheerful enthusiasm describes how the authors grew mice eggs from the ground up, starting from stem cells. The eggs were then fertilized with sperm and implanted in foster mothers. Though the success rate was less than 1%, some of the embryos grew into healthy pups and later into adults with no sign of dysfunctionality. The implications for fertility, but also the prospect of designer babies, are staggering.

From cell to egg to living mammal

The landmark procedure was performed by Katsuhiko Hayashi and colleagues at Kyoto University in Japan and took a decade to shape. At first, they started by coaxing pluripotent stem cells — cells that resemble stem cells and which theoretically can differentiate into any kind of cell in the body — to turn into egg and sperm cells.

In 2012, the Japanese researchers showed they could make fertile eggs from both mouse embryonic stem (ES) cells and induced pluripotent stem cells (iPS). While these iPSCs are similar to embryonic stem cells, the key difference is that they can be made from any cells from the host, like the skin. Pluripotency implies the capacity for stem cells to become a number of different cell types, but that does not necessarily provide the ability to develop an entire organism.

The discovery of induced pluripotent cells is one of the most important breakthroughs in biology because it means that you can now grow an entire liver or kidney that is biocompatible with the patient. In this case, the donor is the patient himself and millions of lives could be saved in the future once scientists get the knack of growing whole, functioning organs in the dish.

But going back to our mice and eggs, it was only this summer that Hayashi and colleagues fitted one of the last pieces of their jigsaw puzzle when they grew mouse ovaries in the lab, then used them to produce fertile eggs.

In total, around 50 eggs were produced, granted many presented chromosomal abnormalities. Still, 75% of the eggs had the correct number of chromosomes and these were mixed with sperm to produce 300-celled embryos.

The embryos were then implanted into foster mothers, but only 11 or 3% grew into full-term pups compared to 62%, in the case of eggs taken from adult mice and fertilized in vitro. The pups that did survive, though, grew into functioning adults.

“This is truly amazing,” says Jacob Hanna, a stem cell biologist at the Weizmann Institute of Science in Rehovot, Israel.  “To be able to make robust and functional mouse oocytes over and over again entirely in a dish, and see the entire process without the ‘black box’ of having to do any of the steps in host animals, is most exciting.”

“Parts of this work were done before — here they are put together in completeness. It’s impressive that they got pups that way,” says Dieter Egli, a stem cell biologist at the New York Stem Cell Foundation Research Institute.

The low success rate means we won’t be seeing human babies born this way anytime soon, but the paper demonstrated a way for infertile women to have their own babies. Another more ethically challenged pathway is that we could one day use this method to make designer babies starting from nothing but a few skin cells, with specific genetic alterations using a tool such as CRISPR-CAS9.

Both scenarios are very far away from becoming reality. The possibilities they entertain can only boggle the mind, though.

Three-parent baby’s birth sparks debate among scientists, public, and officials alike

Five months ago, a three-parent baby girl was born in Mexico. Debate sparked in the wake of her birth, with one side arguing we’re “playing God” while the other points out that if a procedure gives women with a particular genetic disorder a shot at having healthy children, why not use it?

Image credits Pixabay.

Limited information about the birth has published in anticipation of the American Society of Reproductive Medicine’s scientific congress in Salt Lake City, to be held next month, where the case will be debated at length.

What we know up to now is that the baby’s parents are Jordanian and the work was performed by a US team led by Dr John Zhang, of the New Hope Fertility Clinic in New York. The mother has Leigh syndrome, a genetic disorder passed on through mitochondrial DNA. It affects a developing fetus’ nervous system, usually leading to respiratory failure within the first two or three years of life. The mother herself is healthy but has already lost two children to the disease: a girl that lived to be six years old and an eight-month-old baby.

Naturally, the event sparked a heated debate. Critics believe that it’s the same as genetically editing humans or even “playing God”, while supporters say it gives couples a chance at having healthy babies related to them that they might otherwise never have.

So let’s take a look at how it all went down.

The technique used by the New Hope team (called pronuclear transfer) involved taking the nucleus from one of the mother’s eggs — her DNA — and implanting it into a donor egg whose nucleus has previously been removed but retained healthy mitochondrial DNA. Now, what’s really important to keep in mind here is that mitochondria have a special status in the human body — kind of like a friend who keeps crashing on your couch but can cook really well so you keep him around for the quality food. They retain their own DNA, completely separate from our own. They divide when they want, independent of when our cells do it. But they’re really, really good at turning what we eat into ATP, so we allow them their unequaled sovereignty inside our cells.

That’s why many scientists in the field insist the term “three-parent baby” is inaccurate. While mitochondrial DNA is inherited solely from the maternal line, the baby’s actual genetic makeup (sans the mitochondria) only comes from two people.

Still, because the technique isn’t approved in the US, the team invoked the pretty bad-ass argument that “there are no rules” in Mexico and just flew over for the procedure.

“To save lives is the ethical thing to do,” he told New Scientist.

Professor Bert Smeets, the director of the Maastricht University Genome Centre said that the egg replacement technique has already been proven safe by previous experiments and its introduction in clinics is only a matter of time.

“A US-based research group apparently escaped the more rigid regulatory framework in the US to perform this treatment in Mexico. That is a concern, especially as the framework not only safeguards the introduction into the clinic, but also the follow-up of the children born after this treatment,” he added.

“Hopefully, now the first child is born and the heat is off, it takes away the pressure to involve patients in unsecured treatments, when good alternatives are available.”

While specialists in the field welcomed news of Dr Zhang’s work, part of the public opinion and most regulators aren’t so thrilled about it. The British Parliament, for example, voted that creating “three-parent babies” is OK in principle but haven’t yet approved any specific technique to be used. The team also took some criticism for their choice to circumvent legal issues, even if the baby seems to be healthy.

“By performing the treatment in Mexico, the team were not subject to the same stringent regulation as some other countries would insist on. We have no way of knowing how skillful or prepared they were, and this may have been a risky thing to do. On the other hand, we have what appears to be a healthy baby. Because it was successful, fewer questions will be raised but it is important that we still ask them,” said Dr Dusko Ilic of King’s College London.

“It’s unfortunate to have people decide they’re just going to quite willingly engage in this kind of reproductive tourism — to go outside of a system that is in place to create the safest, most scientifically reproducible way forward,” said Lori P. Knowles, assistant professor, adjunct, at the University of Alberta School of Public Health told the CNN.

She also pointed out that four out of the five eggs the team fertilized weren’t viable.

“It shows you the technique itself is still quite fallible,” she said.

“Which is the whole reason you’re supposed to go slowly … and not jump right into creating babies.”

The team’s findings, under the title “First live birth using human oocytes reconstituted by spindle nuclear transfer for mitochondrial DNA mutation causing Leigh syndrome”, have been published in the journal Fertility and Sterility.


Hampton Creek,a San Francisco-based food startup best known for its egg-free mayonnaise spread and cookie dough, has garnered attention at every step of its recent development. Picture on the left is the company's CEO, Josh Tetrick.

The ‘egg conspiracy’: government-back lobby wanted to ruin a startup that makes eggless Mayo

A startling report by The Guardian reveals how the American Egg Board (AEB) – a government-backed board which gets a levy of 20 cents per case of eggs sold by its constituent members – lobbied against a food startup that’s been gathering steam lately. Feeling threatened, AEB used its influence to put pressure on the FDA, USDA and Unilever to basically ruin Hampton Creek’s business. Hampton Creek is a Silicon Valley startup which has so far gathered $120 million in funding. Its flagship products include eggs made out of plants and egg-less mayo, called Just Mayo which Joanne Ivy, president of the American Egg Board, refers to as “a crisis and major threat to the future of the egg product business.”

Hampton Creek,a San Francisco-based food startup best known for its egg-free mayonnaise spread and cookie dough, has garnered attention at every step of its recent development. Picture on the left is the company's CEO, Josh Tetrick.

Hampton Creek,a San Francisco-based food startup best known for its egg-free mayonnaise spread and cookie dough, has garnered attention at every step of its recent development. Picture on the left is the company’s CEO, Josh Tetrick.


The conspiracy was revealed after more than 600 pages of emails between AEB members and other industry key players were collected under the Freedom of Information Act (Foia). In short, the AEB exerted its influence to get Hampton Creek sued by Unilever (lawsuit since ceased), which makes Hellman’s mayonnaise, on the grounds Just Mayo shouldn’t be called mayo given it doesn’t contain eggs. Although the lawsuit was dropped, the FDA – pressured by AEB – ordered Hampton Creek to change its name.The AEB also hired a PR firm to contact bloggers and “encourage their readers to make a conscious decision to choose real and sustainable foods, like eggs, on their path to a healthier lifestyle.” In some of the emails, there was even talk of ordering a ‘hit’ on the Hampton Creek founder.

  • Key findings reported by The Guardian:
  • Outgoing AEB head Joanne Ivy advised Unilever on how to proceed against Hampton Creek after the food giant filed a false advertising lawsuit against its rival last year.
  • The Department of Agriculture’s national supervisor of shell eggs joined the AEB in its attack on Hampton Creek, suggesting Ivy contact the Food and Drug Administration (FDA) directly about Just Mayo with her concerns. The FDA later ruled Just Mayo must change its name.
  • The AEB attempted to have Just Mayo blocked from Whole Foods, asking Anthony Zolezzi, a partner at private equity firm Pegasus Capital Advisors and self-described “eco-entrepreneur”, to use his influence with Whole Foods to drop the product. (Whole Foods still sells Just Mayo.)
  • More than one member of the AEB made joking threats of violence against Hampton Creek’s founder, Josh Tetrick. “Can we pool our money and put a hit on him?” asked Mike Sencer, executive vice-president of AEB member organization Hidden Villa Ranch. Mitch Kanter, executive vice-president of the AEB, jokingly offered “to contact some of my old buddies in Brooklyn to pay Mr. Tetrick a visit”.
  • The AEB’s research arm, the Egg Nutrition Center (ENC), tested the strength of Hampton Creek’s patent for its egg replacer, Beyond Eggs, using a consultant, Gilbert Leveille. Leveille concluded that the patent was “not very strong and could be easily challenged with an alternate product”, he said in an email to Kanter. “Were I in your position I would focus on nutritional quality and on the emerging science, much of which ENC has sponsored,” Leveille wrote.

Josh Tetrick, the founder of Hampton Creek, says he was “shocked” when he was first handed the emails, but not entirely surprised. He says he won’t let himself be bullied and will fight back for the right to the Just Mayo label.

“I’m not entirely surprised that some industries that are lost in the past a little bit are fighting so hard,” he said. “Even though it was joking, some of those notes about putting a hit out – that’s some reckless stuff.”

“We don’t have any plans on changing the name,” he said. “Names matter, and they influence people. We want to connect to the everyday person who’s shopping at the Dollar Tree or shopping at Walmart.”

I’m not sure if anything the AEB has done is illegal per se, but it’s definitely immoral to say the least. Having their tentacles stuck through all sorts of powerful places, some boards and companies think they’re untouchable. But when a competitor is seen as a risk, it has to be liquidated. This time, for the AEB at least, this could severely backfire. But apart from some people losing their heads, will something dramatic change? I don’t know, but we can all at least do our own part. Eggs are important (I eat eggs every couple of days), so there’s no chance in boycotting them (or you could try). You can, however, send a letter to your local producer or distributor and express your disdain.

Scientists 3D print eggs, trick birds into thinking they’re real

It’s more than just a nasty trick – scientists have actually 3D printed eggs to help them better understand bird behaviour. They were especially interested in bird perception and what particular characteristics make them identify real eggs from fake ones.

Image via 3D print.

You can add “fooling birds” to the long list of things that 3D printing can do. Animal behaviorist Mark Hauber of CUNY Hunter College worked with Blender Foundation’s open-source 3D graphics software and based their egg model design on a photograph. The eggs were then printed with four internal shell layers built on top of each other, using 0.3 and 0.2 mm layer thicknesses, and 0% infill.  They then used a syringe to fill them with water and sealed them off.

Faking eggs is actually more common than you might think. Since the 1960s, biologists have made fake eggs for studies of bird behaviour, but 3D printing allows them to take it to a whole new level.

“Instead of using natural eggs, it’s best to use fake eggs, because you can control the size, and shape and the color much more accurately.”

Hauber remembers his first fake egg.

“In 1997, I went into a craft store and bought a beige speckled egg, which looks very much like a cowbird egg,” he says, recalling that it was actually an Easter decoration. He put it in the nest of a gray catbird, which promptly tossed it out.

The problem is that usually, the perfect fake egg can’t be found in a store, which is why they had to rely to 3D printing.

This particular study was aimed at cowbirds, brood parasitic species – they don’t care for their eggs, they simply dump them in he nests of other species. Sometimes the eggs get accepted, but sometimes they get rejected, and researchers wanted to see what makes the difference.

“It could be the size, it could be speckling itself or the lack thereof, and it could be the color — beige versus robin blue,” Hauber explains.

One of these things is not like the other: A 3-D printed model of a beige cowbird egg stands out from its robin’s egg nest mates, though their shape and heft are similar.

Usually, cowbirds manage to fool robins enough for the behaviour to make evolutionary sense, but they have to make the eggs as similar as possible to those of robbins. When it comes to behavioral studies, using fake eggs is better because you can manipulate their characteristics as you please.

They report that the 3D printed eggs stood up pretty well against the real thing – robins accepted them more often than not. Even when the fake eggs were painted blue as a test, robins accepted all the eggs. When they were painted white, they accepted only 21 percent of them – something which is coherent with previous plaster eggs studies. In case you didn’t know, robin eggs are deep blue – and it seems color plays a key role in identifying their eggs.

Christie Riehl, a biologist at Princeton University, was impressed by this study because it used a whole range of fake cowbird eggs — from small round ones to long skinny ones.

“You can imagine, it would be really labor-intensive and time-intensive to individually handcraft eggs that exploit that whole range of variation,” Riehl says, “and it would be very difficult to find commercially available eggs — like even wooden eggs or something — that would have the properties of size and shape that you’re trying to test.”

But an even more refined egg could have even more potential for this kind of research. All in all, Hauber and his colleagues seem to have opened a new door in terms of animal behaviour studies.

Journal Reference: Igic B, Nunez V, Voss HU, Croston R, Aidala Z, López AV, Van Tatenhove A, Holford ME, Shawkey MD, Hauber ME. (2015) Using 3D printed eggs to examine the egg-rejection behaviour of wild birds. PeerJ 3:e965https://dx.doi.org/10.7717/peerj.965

Scientists create see-through eggshell to reduce animal testing

If you’ve ever wondered what happens inside an egg, then science has you covered – researchers have developed transparent artificial eggshells; but they didn’t do this just out of curiosity – they want to create a controlled environment for bird embryo growth and development to aid stem cell research and drug treatment reaction.

When it comes to stem cells, you need a lot of research and testing; for this reason, numerous ‘on-a-chip’ technologies have been developed over the past few years. The point is to develop miniature replicas of human organs, to see how they react when administered certain drugs and medical substances.

“Unlike its ancestor – the conventional ‘lab-on-a-chip’, which is basically chemically based – the current ‘egg-on-a-chip’, intrinsically inherited with biological natures, opens a way to integrate biological parts or whole systems in a miniature-sized device,” the team writes in the journal Science China Technological Sciences.

The benefit here is that these transparent eggs offer a much more accurate view of how real human organs might respond to these treatments – in a way, you’re replacing animal testing with embryo testing, which is more humane, and promises to be more precise. For example, one of the practical applications would be allowing for blood and other types of organic fluids to be injected inside for early diagnosis, and rare gene variations to be cultured inside, Science Alert writes.

Personally, I really like the idea of reducing (even to a small extent) animal testing; the medical importance of animal testing cannot be overstated, but we should really look into alternatives – and this one shows some promise.

This gives researchers an unprecedented view inside the egg, without having to resort to the rather crude technique of windowing; windowing basically involved cutting a hole inside the egg, opening it and closing at will. So far, researchers have managed to culture avian embryos in their artificial, transparent egg  for just over 17 days – about three days before they would be expected to hatch. The researchers didn’t “hatch” living chickens from these artificial eggs and likely won’t do so, unless they have a specific research objective.

Meanwhile, at the very least, researchers will be able to study embryo development without having to cut holes in eggs – that’s something. Hopefully, more will come from this technique.

Journal Reference: LAI YiYu, LIU Jing. Transparent soft PDMS eggshell. DOI: 10.1007/s11431-014-5737-4