Every crop of seedless melons involves the participation of melons with three different genomes. — ELLE TAKES PHOTOS/Pexels
The Brazil nut effectI keep a tin of mixed nuts in the kitchen from which I pick a few a day to snack on, as a means of ensuring that I eat some good fibre every day. And it is always curious why the heaviest Brazil nuts always appear at the top of the tin. This is a gravity-defying phenomenon I think my dog would have found interesting, and as usual, he would be right, because there are several important scientific implications derived from this ‘Brazil Nut Effect’.
For a considerable period of time, scientists have struggled to explain why larger and often heavier particles in a mixture tend to rise to the top when agitated. The phenomenon, officially known as granular convection, occurs not just with nuts, but in cereal boxes, on riverbeds, and even on the surfaces of asteroids.
In 2021, a quirky study led by Parmesh Gajjar at the University of Manchester finally solved the puzzle. Using advanced computed tomography scanning techniques, Gajjar’s team created 181 scans of the Brazil Nut Effect in action as various types of edible nuts were vigorously agitated in a container.
Their findings revealed a surprising mechanism. When first placed in a container, Brazil nuts tend to lie horizontally. As the mixture is shaken, collisions between nuts cause some Brazil nuts to rotate into a more vertical position. This vertical orientation is the key to their rise through the other nuts, as the position creates space for smaller nuts to tumble down and accumulate at the bottom, effectively pushing the Brazil nuts upward.
There were some interesting statistics from the study too. The first Brazil nut typically reaches the top 10% of the mixture height after about 70 shaking cycles, and most of the remaining Brazil nuts reach the same level after around 150 shaking cycles. However, there were always a few that remained at the bottom, possibly because they were irregularly shaped or broken.
The Brazil Nut Effect is not just a curiosity of particle physics; it plays a role in shaping our planet. A study published in 2022 demonstrated that the effect occurs in the sediments on the ocean floor churned by various kinds of sea life (a process called bioturbation), and this profoundly influences the distribution of rare metal lumps, e.g., ferromanganese nodules.
The Brazil nut effect has been applied in geological research and even food production. — JESS VIDE/Pexels
These nodules, which can grow to the size of potatoes, are of increasing interest due to their high concentrations of valuable metals. The study found that particles as small as 1 mm can experience the Brazil Nut Effect in seafloor sediments, explaining why such nodules tend to remain on or near the sediment surface where they can merge and accumulate into larger nodules. Significant areas of the sea floor can then eventually become viable for mineral gathering and mining.
Such studies have led to highly accurate mathematical models based on empirical data, and these models are employed in several diverse areas, such as:
• Manufacturing of pharmaceutical products, by improving the uniformity of active ingredients in medicines.
• Food production, by ensuring the even distribution of ingredients in packaged foods.
• Mining and ore processing, by enhancing separation techniques for materials of different sizes and densities, and also for identifying the optimal regions for mining.
• Geological research, by providing better understanding on the formation of riverbeds and sedimentary processes which have affected the current landscapes.
• The Brazil Nut Effect is even used in space exploration as models can provide insights into the surface composition of asteroids and other celestial bodies based on different gravitational effects.
As our understanding of granular physics widen, so too does our ability to manipulate and harness these natural sorting processes, into areas even more diverse than the ones mentioned above.
From a tin of mixed nuts to the depths of the ocean floor, the Brazil Nut Effect is a reminder that even the most seemingly simple phenomena can lead to the understanding of complex and far-reaching scientific principles.
Hopefully, the next time you grab a handful of mixed nuts, you might now appreciate a little a remarkable natural sorting machine at work, obeying some laws of physics that you would probably never have thought of earlier.
Seedless watermelons
When shopping in a Spanish supermarket earlier this year, I came across some large and completely seedless red watermelons. As I am a fan of lycopene (which is allegedly helpful for preventing prostate issues), it was a delightful find, as such melons have a very high lycopene content. However, the following is not about lycopene (which would be a long ramble), but about how melons were originally bred to become seedless, and it is a good scientific chronicle.
The ingenious story behind the original seedless watermelons involve alterations to the plant genome itself via a process called mutation breeding, whereby plants were deliberately mutated by applying various chemicals. In 1939, the use of the compound colchicine finally started scientists on the road to the seedless melon. It was not an easy, obvious route though.
Most normal cells are diploids, which mean each cell contains two copies of each chromosome. There are exceptions, such as haploids in mammals, but that is another story. In melons, colchicine interferes with structural proteins in cells causing the chromosomes to fail to separate properly during cell division, resulting in events called ploidy changes or variations in the number of chromosome sets in the new cells.
The original experiments in 1939 resulted in tetraploid watermelon plants; i.e., they had four copies of each chromosome in each cell. When these tetraploids were then bred with ordinary diploid melons, the resulting melon plants were triploids (cells with three sets of chromosomes) – and triploids cannot produce seeds because the reproductive cells require an even number of matching chromosome sets.
The story does not end there. Triploid melons still have to be triggered to bear fruit and this is achieved by pollinating female flowers from triploids with pollen from the male flowers of diploid melons.
A recent study used AI to look at the link between current eating patterns and future health outcomes. — POLINA TANKILEVITCH/Pexels
So to produce a seedless watermelon, one first needs to create a tetraploid using colchicine, then mate the resulting tetraploid with a diploid (normal melon), and then the resulting triploid will have to be fertilised by a diploid before we achieve a seedless fruit. Therefore, every crop of seedless melons actually involves the participation of melons with three different genomes.
To increase the success rate, scientists have created diploid plants which do not produce female flowers thereby reducing the chances of two diploid melons producing seeded fruits. And the huge seedless watermelons now often seen in shops are probably due to the application of gibberellic acid-3 (GA3), on the plant during growth. The story behind GA3 is another interesting article for another time.
One can buy seeds from triploid plants but the instructions will always mention a need to have the plant fertilised by another normal melon plant.
Sweet tooth
A recent study using data from over 180,000 UK Biobank participants have uncovered fascinating links between food preferences, health outcomes, and biological markers. The research may one day become the basis of innovative approaches which could revolutionise how we understand the relationship between diet and future diseases.
The study, led by researchers from the University of Manches-ter, used AI to analyse food preference questionnaires and separated the participants into three distinct groups:
1. The health-conscious group: These individuals showed a low preference for animal-based and sweet foods, while favouring vegetables and fruits.
2. The omnivore group: This group had high preferences for all types of foods.
3. The sweet-tooth group: As the name suggests, these participants had a strong preference for sweet foods and sweetened beverages.
The very interesting outcome is how the above dietary preferences correlated with health outcomes. The health-conscious group exhibited lower risks of heart failure and chronic kidney disease compared to the other groups. On the opposite side, the sweet-tooth group faced higher risks of depression, diabetes, and stroke.
However, the study did not limit itself to disease risk. By examining blood samples, the researchers identified unique biological signatures for each group. The health-conscious group, for instance, showed lower levels of inflammatory markers like C-reactive protein, which are often elevated in common metabolic diseases. They also had higher levels of ketone bodies and growth hormone-related proteins, but lower levels of leptin – a hormone that regulates appetite.
Dr. Nophar Geifman, the study’s lead author, stated: “It’s not just about what we eat, but what we prefer to eat, that could be influencing our long-term health outcomes.”
The implications of this research are far-reaching. It opens up new possibilities for personalised nutrition and early disease prevention strategies based on an individual’s food preferences. There may soon be a future where a simple questionnaire about your food likes and dislikes could help predict your health risks and offer tailored dietary recommendations.
The relationships between diet, metabolism, and health are profound and complex, but AI studies like this can pave the way for more targeted and effective approaches to nutrition and disease prevention. The next time you pick the salad dish or the dessert, just be aware that your preferences today might be saying more about your future health than you realise.
The views expressed here are entirely the writer’s own.
