Coming up on this week’s show
- Grapevines are more drought-tolerant than thought
- Can You Get the Flu Twice in One Season?
- A blood test could predict the risk of Alzheimer’s disease
- In wine, there's health: Low levels of alcohol good for the brain
Science News with Sophie McManus, Nevena Hristozova, and JD Goodwin
Grapevines are more drought-tolerant than thought
Vines are more drought-resistant than we previously thought.
Over a period of ten years, grapevines in Bordeaux and the Napa region of California never succumbed to drought, despite seasonal dry periods during this time. The scientists involved found that the lethal limit for the vines was 50% depletion of water – but they only reached this conclusion after greenhouse tests because the field conditions were never so extreme.
Fascinating – quote from SN ‘Typically, when plants become extremely dehydrated and water pressure drops, air bubbles can develop in the xylem, tissue that carries water up from the roots (SN: 05/14/16, p. 32). In plants, as in humans, an air bubble — also known as an embolism — can prove fatal because it stops the transport of nutrients and can cause leaves to drop.’
The team involved used a similar method to a CT scan to monitor the stems and see if these emboli developed. Grapevines sacrifice peripheral parts, such as leaves, to preserve water pressure and avoid fatal embolisms. Different grapevine varieties, like Syrah and Grenache, were all similarly resilient!
This finding is interesting because it reveals just how tough these plants are, but also because this may improve our water usage in drought-prone areas, which will be important in future as climates change. In California, 80% of freshwater resources are used for agriculture. Perhaps this isn’t actually needed for vineyards, perhaps water usage could be reduced. Of course, it is possible that vine survival doesn’t equate to vines THRIVING exactly.
Can You Get the Flu Twice in One Season?
Of course not! Right? We often think that once you’ve got the flu this season you’re off the hook and even if you lick a the door handles in the public transport you can’t get the flu again! BUT, this is actually not true… Generally… A story published in Real Clear Science explains why. The truth of the matter is that the flu virus is pretty much like any other pathogen – it has various strains which have their differences. If you’ve listened to one of our previous episodes where we covered the emergence of superbugs thanks to the increased concentration of trehalose in the food, there we talked how similar conditions in the gut gave rise to two very different yet more virulent than usual strain of otherwise normal gut microbes. While there it was a matter of metabolic differences, in the case of the flu viruses, it’s mostly a matter of structural differences since a virus doesn’t perform metabolic functions outside of the cell.
As all other pathogens, viruses activate the immune system of the host by unwillingly presenting ‘foreign’ molecules to the white blood cells and giving away the fact that they have infected the individual. In the case of viruses, more often than not, the molecule sensed is the surface protein envelope of the virus. Now, not all viruses have protein envelopes, but in the case of the flu viruses – they do so let's stick to this part of the story. When the white blood cells detect these proteins in the bloodstream, they signal to the immune system the threat. The immune system can sense this way many different pathogens.
Different strains of viruses exist all the time, and each flu season there are several which are much more potent than the others and spread widely around the world causing epidemics. This year for example, especially nasty is the H3N2 strain and slightly less popular – the H1N1, both from type B influenza viruses (think different breeds of same subspecies).
Each year, vaccine developers try to anticipate (based on various tests and statistics which strains of which types of flu viruses would be most virulent and would infect the most people. Then they develop the next flu season vaccine based on these results. But sometimes, they are not quite spot on and a more potent ‘unexpected’ strain surprises them. Then, even if you had a flu shot, if it didn’t contain any strain similar enough to provide cross protection you’d still get the flu.
The same way, if you had already the flu, your immune system builds a temporary immunity in terms of antibodies which circulate your bloodstream and if another virus infects you, it gets attached immediately and disarmed. But if the antibodies you have do not detect the surface of this new strain of virus you are exposed to – if it does not possess similar enough features to be recognised by the antibodies, it is as if your immune system senses it for the first time and by the time it is prepared to fight, you are already pinned to bed and in for a few days ‘in hell’.
And all this immune-pathogen warfare is the whole reason why you can indeed get the flu twice in a season and why doctors often recommend if you had the flu early in the season and haven’t had the shot yet, to still get it once healthy to avoid being the unlucky succer who gets it twice.
That should be a familiar sound to you.
It’s a woodpecker, and every time its bill strikes the tree its head absorbs more than ten times the force necessary to give any one of us a concussion. But we’re not seeing woodpeckers staggering around with stars swirling about their heads.
In a new study in PLOS ONE, researchers examined the brains of woodpeckers and found that they in fact had a large build-up of the tau protein in their little brains, something which would be indicative of brain damage in humans. Normally tau proteins can be helpful in stabilizing microtubules and neurons. But too much tau build-up can cause things to go haywire, disrupting communication between neurons. In fact, the pathologies of Alzheimer's and Parkinson's disease are associated with abnormal levels of these proteins
These specimens, pickled in alcohol, were kindly loaned to the researchers from the Field Museum in Chicago and Harvard University. They then removed the birds' brains and took incredibly thin sections and stained them with silver ions to highlight the tau proteins.
What did they find?
They found that the woodpeckers' brains had far more tau protein when compared to the control group, red-winged blackbirds…not known for bonking their heads against trees. So, woodpeckers show signs of what looks like brain damage in people
The researchers speculate that this could possibly be a protective adaptation in woodpeckers. Because every indication shows that these birds are specially adapted for this behavior, and have been doing it for more than 25 million years according to the fossil record.
And if that’s the case, how do these woodpeckers live with this build-up of tau protein, and can this be adapted and applied to humans who suffer from neurodegenerative disease?
That’s for the next study to find out.
A blood test could predict the risk of Alzheimer’s disease
A blood test for Alzheimer’s? Well, maybe. Scientists in Japan and Australia have been working to improve detection of a protein called amyloid-beta in the bloodstream of both Alzheimer’s patients and people without the disease.
This builds on an earlier study, by a different team of scientists – the leader of this earlier study hailed this most recent publication as a ‘fantastic confirmation’ of their work. Always good to be backed up!
As everyone is probably aware, Alzheimer’s is a progressive disease that is the most common cause of dementia. It slowly kills the affected person and we currently have no cure or real treatment. It mainly affects people over 65 but can occur in younger patients, for example in early-onset cases. Any Terry Pratchett fans will be well-aware that he contracted a rare form of early-onset Alzheimer’s in his fifties and died eight years later, after much work to raise awareness and funds for other sufferers. I would recommend reading his account of his diagnosis in the Observer, reprinted ‘a butt of my own jokes’.
Amyloid beta is a protein that accumulates in the brains of Alzheimer’s patients. It’s a sort of ‘sticky’ protein which makes clumps, or plaques, in the brain. This is considered the earliest evidence of pathology in the brain of someone who is developing Alzheimer’s. However, our understanding of Alzheimer’s is far from complete. It is a very complex disease in terms of what causes it and the range of symptoms and rate of progression.
Back to amyloid-beta. Currently, the best ways to check the level of beta amyloid in a person’s brain are via PET scan – a type of brain scan – or a spinal tap, which collects cerebrospinal fluid and is an invasive procedure.
Basically this work – published at the end of January in Nature – used a highly sensitive analysis technique called mass spectrometry to measure the tiny levels of amyloid-beta in the blood of patients (as well as controls). It also compared the ratios of different types of the protein. It is typically hard to detect amyloid-beta in the blood because levels are so low.
This test would avoid either of these options mentioned previously, brain scan or spinal tap. One issue is whether it proves cheaper than a PET scan or a spinal tap – if not, it seems unlikely to be picked up by health services.
We have no real treatment or cure for Alzheimer’s. As global populations age, the disease is becoming more common. This test for a marker of Alzheimer’s doesn’t offer hope of a cure. What it DOES offer is a better way of diagnosing people at the earlier stages of their disease, so selecting people for clinical trials for agents that may to improve outcomes for these people. It’s a hopeful clinical tool which doctors and scientists could use to treat Alzheimer’s in future.
In wine, there's health: Low levels of alcohol good for the brain
YES! On to the booze! Well not really. While some doctors say it’s ok to have a glass of wine with the meal to keep cardiovascular diseases and cholesterol away, others are afraid that it does more harm than helps.
According to a research published in Nature (under the title ‘Beneficial effects of low alcohol exposure, but adverse effects of high alcohol intake on glymphatic function’), and covered by the Uni of Rochester Medical Center’s Newsroom, Dr Nedergaard does not think like that. She and her team went as far to show that in rats, limited and prolonged exposure to ethanol (the main chemical in alcohol drinks) might be helping clear out toxins from the body including the few protein formations blamed for the development of Alzheimer’s.
According to their study, cerebral fluid is pumped into the brain and literally washes away bad chemicals accumulated after intake or as a result of the functioning of the cells.
Animals that were exposed to low levels of alcohol consumption, analogous to approximately 2 ½ drinks per day, actually showed less inflammation in the brain and their glymphatic system was more efficient in moving cerebral spinal fluid through the brain and removing waste, compared to control mice who were not exposed to alcohol. On the other hand, mice which were exposed to long term high doses of alcohol suffered from inflammation of the brain tissues and other severe consequences which made them sick.
Subsequent research has shown that the glymphatic system is more active while we sleep, can be damaged by stroke and trauma, and improves with exercise.
Also a disclaimer is that 2 and a half drinks per day can be way too much for some people, so don’t take this at face value yet! Also, because we are not as of last I checked rats!
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This episode of the Blue Streak Science Podcast comes to you from San Francisco, California; Brussels, Belgium; and Cambridge, England.