Sunday 25 February 2024

Male vs female brain, whale songs & human cooperation | Last Week in Science (25th Feb 2024)

Is the male and female brain really different?

Medically speaking, we know that some neuropsychiatric and neurological diseases affect women more than men. Hormones are/may be one of the reasons for this difference. But is the brain of a male individual different from a female's? 

Researchers at Stanford University used artificial intelligence to find it out. They trained the AI to identify MRI scans of females and males by showing it brain scans of both the sexes. When tested with 1500 brain scans taken from individuals across USA and EU, the AI could correctly identify the sex of the individual. This increased the confidence in the training as it could work on diverse populations. So, what do we do by identifying males and females just by looking at a brain scan?

The scientists digged into how the AI was identifying the sex of the individual. This process makes it an explainable artificial intelligence instead of a black box of mystery. What they observed was that the identification was happening by studying the organization of three different brain regions, default mode network - which helps in understanding of self, striatum - which plays a role in reward, and limbic network - which is involved in learning amongst its other functions. 

What makes their study useful according to the authors is - 1. The differences in the male and female brain organization that they have undercovered can help in research for neuropsychiatric and neurological diseases. 2. Their AI model will help in identifying the brain circuits responsible for any type of behaviour - like say for a learning disability.

Reference: Stanford Medicine study identifies distinct brain organization patterns in women and men

What makes you cooperate?

Helping your family or friend makes sense, although it may not to everyone, but helping someone whom you would never meet again or someone from whom you have nothing to gain, how do we explain that? The origin of these one time altruistic interactions are difficult to explain. What we know about human cooperation is that when two individuals will be meeting repeatedly then they would want to ensure they remain on good terms so they cooperate, again does not apply to all individuals and all interactions. But then this hypothesis cannot explain the one time interactions. Another hypothesis is 'group competition'. A group which has more cooperative individuals would be at an advantage than a group with selfish or non-cooperative (the terms can be used interchangeably in this context) individuals. But both the hypotheses are not sufficient to explain why 'cooperation' or to say 'altruism' as a trait evolved and remained in today's population (and society). 

Researchers in University of Zurich created a model to understand this 'cooperative' human behavior. They then conducted a test on two different groups in Papua New Guinea. They paired individuals - once with a member of their own group (in-group) and then with a member of the other group (out-group). They asked the first member to give a certain amount of that individual's money to their partner following which they would give the double of that amount to their partner. They saw that in case of in-group partners the first member gave a higher sum and the second member gave back a much higher sum of money. While in the case of out-group pairings - the first member gave a smaller sum and the receiving individual gave a much lesser sum to the first one.

Now, when the researchers tested this result in their model then they found that such type of behaviour can explain the cooperation they saw in Papua New Guinea by a combination of both repeated interactions and group competition.

Reference: Why reciprocity is common in humans but rare in other animals

Eerie whale songs

Sailors would often tell stories of haunting sounds that could be heard in the ocean. It was only when the recordings of these songs became available to marine biologists that we understood that these sounds were whale songs. The mystery of how the songs were produced by the whales remained unexplainable for long because of the difficulty of studying these large marine mammals. But the researchers in Denmark might have found a piece of this puzzle that can help understand how whales are producing these sounds. The most interesting of the facts is that some of these whales can produce two different sounds at the same time. So, let us see what these scientists found.

Larynx the sound box has vocal cords or vocal folds present that is responsible for producing sound in mammals. As air passes through the larynx vocal cords - present on either side of the tube shaped larynx - vibrate to produce sound. The scientists studied the whale larynx dissected out from the dead bodies of whales. They passed air from the whales larynx to understand how sound is being produced. Now, the larynx in the whale has two different compartments unlike the larynx in land animals. A layer of fat - fat cushion, lines one side of the larynx creating a second compartment between fat cushion & vocal folds. Now, this creates two different surfaces - because of the presence of two vocal folds - lining next to the fat cushion that can vibrate as sound gets squeezed between the fat cushion and the vocal folds. Vibration of these two different surfaces can explain the production of two sounds at the same time. It also appears that the major sound production is via fat cushion- vocal fold instead of the air passing through the vocal folds.

This explanation still needs to be tested further in models where larynx is in an environment that still has the surrounding tissues intact. Another question that needs to be answered is how the sound is being produced underwater. And lastly, it would be interesting to see how some distinct and unusual whale sounds like - 'gunshot' and 'star wars' light-saber' like sounds are produced by whales.

Reference: An innovative way for whales to sing

Sunday 18 February 2024

Polar bears, joking apes, & predicting dementia | Last Week in Science (18th Feb 2024)

Will they survive?

With the global average temperature crossing the 1.5 degrees mark, the concern for animals in the Arctic and Antarctic has increased. Polar bears are one such organism that have been predicted to not survive the longer ice free days of the Arctic based on the studies done so far. Although, what these studies did not include were the differences in behavior, age, activity and thus energy expenditure of different bears. Researchers in Canada and USA studied polar bears in the Western Hudson bay to observe the differences between individuals.

Polar bears hunt and survive on seals exclusively. During the ice free period of summers they spend time on land - which has now increased to around 130 days and is expected to increase in the coming years based on the changes in the climate due to global warming. The scientists hypothesized that adult polar bears which have larger mass and more fat than females and younger bears would be able to hibernate and conserve energy when on land. While the younger bears would spend more time looking for and eating food sources that are available on the land in the absence of seals during that time of the year - with females foraging more as compared to younger adult males because of their smaller size - less fat and so more need for energy.

The scientists made these observations by making the bears wear GPS equipped cameras. They found that the age and size did not affect the hibernating or foraging behaviour of polar bears. Their energy expenditure based on their activity was dependent on the behaviour that had a high variation. Even though swimming is a high energy consuming activity, yet they found some of the bears, both males and females swimming. Polar bears were seen to lose body mass as the food available on land could not meet their energy needs. During hibernation, bears depend on the fat reserves in their body. But the scientists observed loss in lean muscle body mass instead of the depletion of fat reserves. It is another proof that the bears will not be to survive for long on the land for long because of eventual starvation. Although, it may be too complex to predict the overall behavior and adaptations of bears because of the high variations observed, the study still reiterated what we know.

Reference: Polar bear energetic and behavioral strategies on land with implications for surviving the ice-free period

Apes have a sense of humour

"Humor is mankind's greatest blessing." - Mark Twain

Humorous behaviour like joking and teasing (without harming the other individual) seems to increase bonding amongst individuals. Even infants as young as 8 months of age, who haven't even begun speaking show teasing behaviour like offering their toys and then pulling it back or taking something the moment you want to use it. 

Guess what, such behaviour is not just seen in humans but great apes like bonobos, gorillas, orangutans, and chimpanzees also show such teasing amongst themselves. Scientists in the University of California recorded these four different great ape species and got some 75 hours of video footage. They looked for signs of playful teasing, which is neither aggression nor play but one sided and involved one individual being targeted. This mostly involved poking, hitting, or pulling hair in the case of orangutans. This kind of behavior is also observed in human siblings and friends who are of the same age, but in the great apes the younger ones engaged with the adults to show such playful teasing.

But why study teasing in apes? Humour is a behaviour that utilises a lot of mental ability - judging of the situation, prediction of others' response and seems to be a way for bonding amongst individuals. Presence of this behaviour in apes who share a common ancestor with humans indicate that humourous behaviour evolved some 13 million years ago. So similar studies can help us in better understanding evolution of other behaviours and emotions. 

Reference: Spontaneous playful teasing in four great ape species 

Blood tests for early diagnosis of dementia

Dementia is a condition that is associated with memory loss and gradual decline of brain functioning. It is a condition seen in many neurodegenerative disease. It is usually too late by the time the disease is diagnosed because of the absence of diagnostic tests. Brain scans are done only after a substantial decline in mental functioning is seen, which shows the damage inside the brain. Scientists have been looking for blood tests that can help in the diagnosis of diseases that cause dementia before the symptoms appear.

Scientists at Fudan University, China have now found a blood test that can diagnose dementia as early as 15 years before the symptoms start to appear. They looked at some 52,000 human samples (taken from UK Biobank) and identified 1400 individuals that had developed dementia when followed up after 14 years. Using this data, they could find four different proteins in the blood that were found to have increased in individuals that developed dementia 14 years before they developed dementia.

We can hope for a blood test to be available once this study is tested and repeated again for consistency and robustness.

Reference: Plasma proteomic profiles predict future dementia in healthy adults

Sunday 11 February 2024

Firefly petunia, fighting cancer using its trick, & solar farms to bring rains | Last Week in Science (11th Feb 2024)

Firefly petunia that glows in the dark

Glowing green colored petunia plant leaves in dark
Credit: Light Bio

Who doesn't get mesmerized by the flickering light coming from the glowing fireflies in the dark? Imagine having a plant that would glow in the dark without needing any extra effort on your part, but just the regular and usual care that all plants need. I would definitely want one for myself and especially when you can get it for just under Rs 2500 ($29). Sounds like a cool Valentine's gift!

Firefly petunia are now open for pre booking on Light Bio's website  - the makers of bioluminescent plants - but for now they are only available in the USA. Fireflies have an enzyme - luciferase that generates light via a chemical reaction. Luciferase has been used in molecular biology research to answer various research questions ranging from whether a certain gene is on or not to measuring levels of different proteins. Plant biologists have also used it for similar purposes. So, we already had the technique and tools to genetically engineer such plants since 1980s. But the glow in such plants was faint and would require special chemicals to be supplied to the plants for them to luminescence. So, what is different in firefly petunias is the luciferase enzyme that has been taken from a mushroom. It glows constantly with an intensity as bright as the moon light and does not require any extra chemicals. The white flowers in the day time are visible with this soft green glow at night.   

While the concern for genetically engineered plants to be spreading their artificially introduced genes in other plants remain. The researchers and the founders have assured that petunia being a non invasive species do not pose any such risk. What makes this an achievement is the potential use of this gene editing technology to produce plants that can glow when stressed or infected and signal to farmers that they need attention. And yes, sensitising people about the benefits of genetic engineering by such beautiful plants is a bonus.

Source: Glow way! Bioluminescent houseplant hits US market for first 

Fighting cancer using its trick

You must have come across the news of the first patient who got cancer free after using CAR-T cell therapy that was approved last year and is developed by ImmunoACT - an Indian company. It is a huge achievement for the country. The treatment cost 42 lakhs which would have been 4 crores had it been taken in the USA or EU.

Let us see what CAR-T cells are. T cells are one of the immune cells of the body that can identify and destroy cancer cells in the body. But they fail at times and this is where gene editing can help. T- cells from the patients can be taken, edited and equipped with CAR (chimeric antigen receptor) that can help the CAR-T cell to recognize and kill the cancer cells in the body. The limitation of this therapy is - besides being super expensive that it can be used only to treat blood cancers. How can we tinker with the CAR-T cells to make them reach cancers in other places like breast or lungs? Scientists that co-founded Moonlight Bio have the answer. They used one of the mutations that helps cancer cells to spread through the body to make CAR-T cells reach tumors present inside organs. The therapy has been tested in mics so far but they are going to bring it out for humans and get the clinical trials started in the next 2-3 years. 

The concern of these modified CAR-T cells carrying a mutation that is present in the cancer cells itself which can cause cancer developing from the CAR-T cells has been addressed as the therapy has been found to be not just effective but also safe in mice. We can hope for more efficient and less expensive cancer therapies to be coming out soon.

Source: Cancer’s power harnessed — lymphoma mutations supercharge T cells

Solar farms to bring rain storms

We have a technology to artificially produce rain by seeding clouds. Remember when there were plans by the government to use it to mitigate air pollution in Delhi! Cloud seeding is regularly used in desert areas like in the UAE. But there is another way to produce rain.

In 2020, scientists modeled and predicted if there is a solar farm as large as the size of 1/3rd the size of India then it can cause rainfall in that area by hot air rising above leading to cloud formation and rainfall. Producing a solar farm this large is not possible and it would also impact the monsoon in other nearby regions. In a new modeling study, scientists discovered that if the solar panels are dark that completely absorb all the light without reflecting any then a smaller sized solar farm - as large as the Indira Gandhi International airport can bring about rainfall in that area. Now this is something that can be tried out in deserts!

Source: massive-solar-farms-could-provoke-rainclouds-desert

Sunday 4 February 2024

X chromosome, training AI, anti-obesity drugs for AD & PD | Last Week in Science (4th Feb 2024)

Is X making you sick?

Auto immunity is when your immune system starts attacking your own body. Two thirds of the cases of autoimmune diseases are seen in females. Sex hormones are thought to cause this higher susceptibility of females to develop autoimmune diseases like rheumatoid arthritis. X chromosome is also seems to be a probable culprit for development of autoimmunity.

Genetically human females and males are different because of the presence of two X chromosomes in females and one X and one Y chromosome in males. To compensate for the double dose of genes on the X chromosome in females, one of the chromosomes is made inactive. This process coats the chromosome with RNA and proteins. Xist is the RNA that wraps around one of the X chromosomes in the cells of human females.

In a recent study, it was found that auto antibodies are formed in the body that attack the proteins associated with Xist. Now, since all the cells of human females have Xist so it puts them at a higher risk of developing such auto antibodies and in turn autoimmune disease. Individuals that had auto immune diseases also had these auto antibodies present in their blood. Using this information the scientists will now be developing tests for early detection of autoimmune diseases. These auto antibodies can also be used for developing new treatment methods.

Anti-obesity drugs can treat Alzheimer's and Parkinson's Disease

The bestseller anti obesity drug of 2023 - semaglutide suppresses appetite and makes the brain believe you are full. It is used to treat diabetes and it also causes weight loss. It has recently found to decrease the risk of heart disease. And this drug has also shown to suppress inflammation - a process that happens when the immune cells are in the fight mode either attacking and/or clearing up the dead cells and the collateral damage after the attack is over. There are many diseases where the inflammation is either the cause or the effect. And semaglutide like drugs seem to reduce inflammation everywhere in the body.

There is brain inflammation in neurodegenerative diseases like Alzheimer's and Parkinson's Disease - where there is memory loss or individuals lose control of their motor function leading to tremors and falls. Currently, drugs similar to semaglutide are being tested as a medicine for AD and PD. And it is showing promising results, improving symptoms of these neurodegenerative diseases.

Training AI with the eyes of a toddler

Is language inherent or acquired? We all learn language when we are young. Can we train an AI by providing the same kind of experience? And if yes, then what will we gain out of this experiment?

Researchers at New York University made a toddler wear a camera on his head for 1 hour per week from the age of six months to two years. This footage was then used to train an AI algorithm. The audio was given as the transcript - thus the algorithm could associate words with the images in the video. This algorithm was not trained any language and it could still identify some of the words by the image and word association like crib and ball. This experiment challenges the view that language is inherent because the computer program could learn it without having no prior information of how language works.