Jun 22, 2021 07:27 PM
(This post was last modified: Jun 22, 2021 07:32 PM by C C.)
“Black fungus” surges in India—thousands blinded, maimed, dead
https://arstechnica.com/science/2021/06/...-in-india/
EXCERPTS: So-called “black fungus” infections are surging in India in the wake of a devastating wave of COVID-19. The rare but devastating infection can destroy the eyes and spread to the brain.
[...] Past medical reviews have estimated that the fungal infection—mucormycosis—has an overall fatality rate of around 50 percent. ... In India, the fungi appear to be mainly taking root in the nose and sinuses, where they can spread to facial bones, eyes, and even the brain. Once an infection is established, it can quickly become aggressive and lead to tissue death...
Mucormycetes are a ubiquitous group of molds, and they typically only strike immunocompromised patients, such as those with diabetes. The soil-lurking molds love acidic conditions, making patients with diabetic ketoacidosis—a complication in which the blood becomes acidic—particularly vulnerable... (MORE - details)
Secret workings of smell receptors revealed for first time
https://www.quantamagazine.org/secret-wo...-20210621/
INTRO: Smell, rather than sight, reigns as the supreme sense for most animals. It allows them to find food, avoid danger and attract mates; it dominates their perceptions and guides their behavior; it dictates how they interpret and respond to the deluge of sensory information all around them.
“How we as biological creatures interface with chemistry in the world is profoundly important for understanding who we are and how we navigate the universe,” said Bob Datta, a neurobiologist at Harvard Medical School.
Yet olfaction might also be the least well understood of our senses, in part because of the complexity of the inputs it must reckon with. What we might label as a single odor — the smell of coffee in the morning, of wet grass after a summer storm, of shampoo or perfume — is often a mixture of hundreds of types of chemicals. For an animal to detect and discriminate between the many scents that are key to its survival, the limited repertoire of receptors on its olfactory sensory neurons must somehow recognize a vast number of compounds. So an individual receptor has to be able to respond to many diverse, seemingly unrelated odor molecules.
That versatility is at odds with the traditional lock-and-key model governing how selective chemical interactions tend to work. “In high school biology, that’s what I learned about ligand-receptor interactions,” said Annika Barber, a molecular biologist at Rutgers University. “Something has to fit precisely in a site, and then it changes the [protein’s atomic arrangement], and then it works.”
Now, new work has taken a crucial and much anticipated step forward in elucidating the beginning stages of the olfactory process. In a preprint posted online earlier this year, a team of researchers at Rockefeller University in New York provided the first molecular view of an olfactory receptor as it bound to an odor molecule. “That’s been a dream in the field” ever since olfactory receptors were discovered 30 years ago, said Richard Benton, a biologist at the University of Lausanne in Switzerland who was not involved in the new study.
“It’s unequivocally a landmark paper,” Datta said. “Although we’ve had access to receptors as molecules for a long time, no one’s ever actually seen with their eyes what it looks like when an odor binds to a receptor.”
The result goes a long way toward confirming how animals identify and discriminate among astronomical numbers of smells. It also sheds light on key principles of receptor activity that might have far-reaching implications — for the evolution of chemical perception, for our understanding of how other neurological systems and processes work, and for practical applications like the development of targeted drugs and insect repellents... (MORE)
Why single people smell different
https://www.bbc.com/future/article/20210...-different
EXCERPTS: Our body odour can reveal details about our health, like the presence of diseases [...] "It can also reveal information about our diet," says Mehmet Mahmut, an olfaction and odour psychologist at Macquarie University, Australia. "There are a couple of studies that kind of contradict, but my group found that the more meat you consume the more pleasant your BO smells."
Men find women's body odour more pleasant and attractive during the follicular phase of the menstrual cycle, when women are most fertile, and least pleasant and attractive during menstruation...
[...] While it can change depending on our diet and health, a lot of what makes our smell unique is determined by our genetics. ... Identical twin body odour is so similar that matchers in this experiment even mistook duplicate T-shirts from the same individual as two twin T-shirts.
"This is important because it shows that genes influence how we smell," says Agnieszka Sorokowska [...] "so, we might be able to detect genetic information about other people by smelling them."
Your HLA profile is very likely to be different to everyone else you meet – though some people, like your close relatives, will be more similar to you than others. From a genetic point of view, it is an advantage to have a child with someone who has a dissimilar HLA profile. “If you have a partner who is genetically dissimilar in BO and immune profile, then your children will have a better resistance to pathogens,” says Sorokowska.
[...] Do humans use genetic information hidden in body odour to choose their partners? It would seem not. In a study of almost 3,700 married couples, the likelihood of people ending up with a HLA-dissimilar partner was no different to chance.
[...] Couples who had high HLA-dissimilarity – which presumably happened by chance – had the highest levels of sexual satisfaction and the highest levels of desire to have children. This link was more strongly seen in women. Women partnered with HLA-similar men reported more sexual dissatisfaction and lower desire to have children. Though when evidence from multiple studies is taken into account, the effect might not be conclusive.
[...] real-life scenarios are too complex to use scent information accurately. Our other senses can distort the information we take in from smell.
[...] In a separate study by Mahmut, strangers' BO also smelled stronger than married men's BO. He speculates that this might be because "there's some evidence of a correlation between high testosterone levels and stronger BO. We know there is an association between a reduction in testosterone and getting older, which might be due to the things going on in a married man's life as he gets over 40 – prioritising children and things like that. Men who are in relationships, and more so those that have had children, have lower testosterone.
So, we know that we give off information about our reproductive quality in our BO, and we know that we can detect it, but we don’t act on it. Should we?
"If your sole interest is finding a partner with good genes, then perhaps you should pay attention to their smell," says Sorokowska. "But for most people that is not the most important thing, and most people don't do it."
Mahmut agrees: "The usefulness of scent has somewhat decreased. We spent tens of thousands of years disguising what we smell like." (MORE - missing details, links to studies)
https://arstechnica.com/science/2021/06/...-in-india/
EXCERPTS: So-called “black fungus” infections are surging in India in the wake of a devastating wave of COVID-19. The rare but devastating infection can destroy the eyes and spread to the brain.
[...] Past medical reviews have estimated that the fungal infection—mucormycosis—has an overall fatality rate of around 50 percent. ... In India, the fungi appear to be mainly taking root in the nose and sinuses, where they can spread to facial bones, eyes, and even the brain. Once an infection is established, it can quickly become aggressive and lead to tissue death...
Mucormycetes are a ubiquitous group of molds, and they typically only strike immunocompromised patients, such as those with diabetes. The soil-lurking molds love acidic conditions, making patients with diabetic ketoacidosis—a complication in which the blood becomes acidic—particularly vulnerable... (MORE - details)
Secret workings of smell receptors revealed for first time
https://www.quantamagazine.org/secret-wo...-20210621/
INTRO: Smell, rather than sight, reigns as the supreme sense for most animals. It allows them to find food, avoid danger and attract mates; it dominates their perceptions and guides their behavior; it dictates how they interpret and respond to the deluge of sensory information all around them.
“How we as biological creatures interface with chemistry in the world is profoundly important for understanding who we are and how we navigate the universe,” said Bob Datta, a neurobiologist at Harvard Medical School.
Yet olfaction might also be the least well understood of our senses, in part because of the complexity of the inputs it must reckon with. What we might label as a single odor — the smell of coffee in the morning, of wet grass after a summer storm, of shampoo or perfume — is often a mixture of hundreds of types of chemicals. For an animal to detect and discriminate between the many scents that are key to its survival, the limited repertoire of receptors on its olfactory sensory neurons must somehow recognize a vast number of compounds. So an individual receptor has to be able to respond to many diverse, seemingly unrelated odor molecules.
That versatility is at odds with the traditional lock-and-key model governing how selective chemical interactions tend to work. “In high school biology, that’s what I learned about ligand-receptor interactions,” said Annika Barber, a molecular biologist at Rutgers University. “Something has to fit precisely in a site, and then it changes the [protein’s atomic arrangement], and then it works.”
Now, new work has taken a crucial and much anticipated step forward in elucidating the beginning stages of the olfactory process. In a preprint posted online earlier this year, a team of researchers at Rockefeller University in New York provided the first molecular view of an olfactory receptor as it bound to an odor molecule. “That’s been a dream in the field” ever since olfactory receptors were discovered 30 years ago, said Richard Benton, a biologist at the University of Lausanne in Switzerland who was not involved in the new study.
“It’s unequivocally a landmark paper,” Datta said. “Although we’ve had access to receptors as molecules for a long time, no one’s ever actually seen with their eyes what it looks like when an odor binds to a receptor.”
The result goes a long way toward confirming how animals identify and discriminate among astronomical numbers of smells. It also sheds light on key principles of receptor activity that might have far-reaching implications — for the evolution of chemical perception, for our understanding of how other neurological systems and processes work, and for practical applications like the development of targeted drugs and insect repellents... (MORE)
Why single people smell different
https://www.bbc.com/future/article/20210...-different
EXCERPTS: Our body odour can reveal details about our health, like the presence of diseases [...] "It can also reveal information about our diet," says Mehmet Mahmut, an olfaction and odour psychologist at Macquarie University, Australia. "There are a couple of studies that kind of contradict, but my group found that the more meat you consume the more pleasant your BO smells."
Men find women's body odour more pleasant and attractive during the follicular phase of the menstrual cycle, when women are most fertile, and least pleasant and attractive during menstruation...
[...] While it can change depending on our diet and health, a lot of what makes our smell unique is determined by our genetics. ... Identical twin body odour is so similar that matchers in this experiment even mistook duplicate T-shirts from the same individual as two twin T-shirts.
"This is important because it shows that genes influence how we smell," says Agnieszka Sorokowska [...] "so, we might be able to detect genetic information about other people by smelling them."
Your HLA profile is very likely to be different to everyone else you meet – though some people, like your close relatives, will be more similar to you than others. From a genetic point of view, it is an advantage to have a child with someone who has a dissimilar HLA profile. “If you have a partner who is genetically dissimilar in BO and immune profile, then your children will have a better resistance to pathogens,” says Sorokowska.
[...] Do humans use genetic information hidden in body odour to choose their partners? It would seem not. In a study of almost 3,700 married couples, the likelihood of people ending up with a HLA-dissimilar partner was no different to chance.
[...] Couples who had high HLA-dissimilarity – which presumably happened by chance – had the highest levels of sexual satisfaction and the highest levels of desire to have children. This link was more strongly seen in women. Women partnered with HLA-similar men reported more sexual dissatisfaction and lower desire to have children. Though when evidence from multiple studies is taken into account, the effect might not be conclusive.
[...] real-life scenarios are too complex to use scent information accurately. Our other senses can distort the information we take in from smell.
[...] In a separate study by Mahmut, strangers' BO also smelled stronger than married men's BO. He speculates that this might be because "there's some evidence of a correlation between high testosterone levels and stronger BO. We know there is an association between a reduction in testosterone and getting older, which might be due to the things going on in a married man's life as he gets over 40 – prioritising children and things like that. Men who are in relationships, and more so those that have had children, have lower testosterone.
So, we know that we give off information about our reproductive quality in our BO, and we know that we can detect it, but we don’t act on it. Should we?
"If your sole interest is finding a partner with good genes, then perhaps you should pay attention to their smell," says Sorokowska. "But for most people that is not the most important thing, and most people don't do it."
Mahmut agrees: "The usefulness of scent has somewhat decreased. We spent tens of thousands of years disguising what we smell like." (MORE - missing details, links to studies)