Friday 12 April 2024

Exercise & time of the day | Last Week in Science (14 April 2024)

Exercise and the time of the day

Have you wondered what time of the day is best to exercise? While we may not know if it applies to all but a recent study conducted at University of Sydney has provided an answer for people with obesity.

Physical activity stretches or chunks of more than three minutes that makes one breathless reduce the risk of developing heart disease and type 2 diabetes. The kind of vigorous activity that makes one breathless increases one's oxygen demand and so increases the heart rate to supply more blood and oxygen to the muscles that are being exercised. In stretches of strenuous exercise that last less than 3 minutes, the muscles can work even without oxygen and has been found to be less beneficial.

Researchers recorded physical activity that included more than 3 minutes of strenuous activity in 30,000 individuals using wearable devices - like the one that is used to count steps. Their goal was to understand what time of the day - morning, afternoon, or evening is most beneficial for exercising in people with obesity. These 30,000 individuals were tracked for 8 years to record the development of cardiovascular disease, diabetes, or death. The researchers found that physical activity done during late afternoon or evening time is most effective in reducing the risk of heart disease and type 2 diabetes. The researchers did not include the total time of strenuous exercise which they suggest to be studied in future.

Self-control vs willpower

Although self-control and willpower are used interchangeably but lately the difference between the two has been recognized. Willpower can be thought of as an internal force to exercise self-control that can also be achieved via external strategies of incentives, restrictions, and punishments. Despite the effectiveness of such strategies, there seems to be a reluctance in using external strategies for self control to achieve one's goals.

To understand this reluctance, researchers designed multiple tests which were taken by 2800 participants in the United States. In one of the tests, participants were given 0.5$ and asked to loan it to a hypothetical second player. The amount would get tripled when received by the second player to 1.5$ and the second player would have the option to either keep it to themselves or split the half 0.75$ with the first player. More than 69% of the participants passed the money to the second player who exercised his willpower to achieve his goal instead of using an external strategy like a blocking app to not get distracted.

The scientists behind the study suggest that the use of incentives may be seen as an individual's admission of past failures to achieve something through self-control, which is perceived as a moral failure, thereby diminishing their integrity. Thus, despite the effectiveness and acceptance of external strategies and incentives in achieving goals or breaking habits, individuals who use them are perceived as less trustworthy. 

One of the interesting findings of the study was that the participants' trust did not depend on the usage of an external method but rather on the choice that a hypothetical individual made to use it. The study also revealed that individuals are more likely to use incentives when they know others won't find out. 


Saturday 6 April 2024

Growing mini livers, the left hand, & safe weight gain during pregnancy | Last Week in Science (7 April 2024)

Growing mini livers inside a human body

In a first of its kind clinical trial, a patient with liver failure has been administered cells that will grow into mini livers inside their body.

Liver is essential for our survival as it is involved in removing toxins from blood, helping in digestion and utilization of food. The current treatment for liver failure is liver transplant from a healthy donor. Transplant requires not just a donor but also the matching of the donor with the recipient so that the body's immune system does not attack the donor liver, which too can be fatal. LyGenesis, a company in Pennsylvania USA, has come up with an innovative solution to get past the shortage of a matching liver for transplant. This treatment strategy worked well in mice, dogs, and pigs and has now been tested in a human.

The treatment involves injecting donor liver cells into the recipient's lymph nodes present near the liver. Lymph nodes are present in large numbers in the body and help the body to fight infections, so modifying a few of them should not cause any harm. The injected lymph nodes have been shown to form mini livers and taking over the functions of liver. The patient receiving this treatment is now on immunosuppressive medications and will be followed up to find if the treatment has been successful.

LyGenesis has plans to grow kidneys and pancreas too in the near future if the mini livers are successful. They also plan to use patient's own stem cells so that there is no risk of rejection of the donor cells.

Reference: ‘Mini liver’ will grow in person’s own lymph node in bold new trial

The left hand

Are you left handed and wonder what made you so? Around 10% of the global population use their left hand predominantly for doing most of their tasks.

Multiple genes have been associated with left handedness in the studies done so far. One such gene is TUBB4B that forms tubulin protein. Tubulin forms microtubules that are required for movement of cell, its shape, its growth and division. Defects in tubulin gene is seen in many neurodevelopmental diseases.

In the current study, researchers in the Netherlands have found a rare mutation in the tubulin gene that is present in left handed people. This mutation is different than the one which causes diseases. So, how does a protein decide which hand you would use? The researchers think that when the brain is developing in the fetus - tubulin makes the right side of the brain different from the left, thus making right side dominant. The right side of the brain controls the left side of the body and vice versa . This does not mean that there are left or right brained people as for most of the functions - language processing, making art, and feeling emotions both sides of the brain have different roles to play. 

The role of tubulin seems to be important in shaping the asymmetry of brain. Brain asymmetry means that the left and right hemispheres are not exactly the same in terms of which aspects of a function of the body they control. Further studies on the role of tubulin in making the brain asymmetric may hold answers for how the brain develops and how minor changes can lead to diseases.

Safe weight gain during pregnancy in obese women

For the healthy growth of the developing embryo, more calories and thus weight gain is essential during pregnancy. WHO recommends guidelines for how much weight gain is required during pregnancy based on the weight of the mother. No weight gain is needed in the first trimester, but second trimester onwards a steady increase in weight every week is advised.

A weight gain of 5 - 10 kgs is advised for obese women (early pregnancy BMI before 14 weeks' gestation ≥30) during pregnancy, but the absence of systematic studies have made weight gain guidelines risky for obese women and the baby. Obesity increases the risk of diabetes or increased blood pressure during pregnancy and chances of stillbirth or death of the baby. It can also cause heart diseases after pregnancy. The chances of developing these conditions increase with weight gain during pregnancy.

A recent study at Karolinska Institutet, Sweden has found that a minimum of 5 kgs weight gain may not be needed. The scientists studied the medical records of 15,760 pregnant women with obesity in Sweden. They found that 2-3 kgs of weight gain is healthier and beneficial for both the mother and the baby as opposed to the recommended 5 kgs. The study suggests the need for revising the weight gain guidelines for obese women so as to reduce the pregnancy related complications for the baby or the mother.

Edited by Ashish Gourav

Sunday 31 March 2024

Choosing & storing permanent memories, and robot's smile | Last Week in Science (31st Mar 2024)

Choosing long term memories to save

Our daily experiences and events are encoded and saved in the brain as memories. Some of the memories are saved permanently while others are not. We do not know how the memories are chosen by the brain for permanent storage. A recent study conducted at New York University has now provided an answer.

For this study, scientists made mice explore a maze multiple times and gave them sugary treats at the end of each run. The brain activity of the mice was recorded while they were hard at work. After some of the maze runs, a particular type of brain activity was seen called 'sharp wave ripples' in some of the neurons. This activity represents a group of neurons getting activated together repeatedly in a rhythm. For different runs of the maze i.e, for different memories, the group of neurons were also different.

When the mice slept after all these maze runs and recordings, the rhythmic activity of neurons for some of the memories were repeated 1000s of times. The brain replayed only those memories that had shown wave ripples 15 - 20 times during the maze runs and others were not replayed. The replaying of memories 1000s of times strengthens the memory to store it for long term. Thus, the brain uses sharp wave ripple activity to select a memory for permanent storage.

Reference: Mechanism found to determine which memories last

How do memories get stored permanently?

According to our current understanding, our memories are encoded in micro circuits of neurons that form in the hippocampus. A micro circuit of neurons is called an engram and it represents the physical form of a memory. For the engram to form and persist, the individual neurons of the engram undergo biochemical changes to maintain strong connections with other neurons of the engram. One such change is damage to the neuron's DNA that gets corrected immediately.

A new study has found that there are neurons other than engram neurons in the hippocampus in which DNA breaks in response to/for memory formation but do not get repaired immediately. These neurons activate a protein called TLR9 in response to the DNA damage that further activates other proteins which help to repair the DNA damage. When scientists removed TLR9 from mice and then tested their memory, they found that the mice could not remember what they learnt. 

This study also shows that there are other group of neurons in addition to the engram neurons that are responsible for storage of permanent memories.

DNA damage is usually associated with diseases like cancer, neuro psychiatric and neurological conditions like neurodegeneration, where memory and learning is often affected. It is therefore intriguing that how such a dangerous step like DNA damage is used by our neurons for storing memory. A better understanding of this mechanism of memory storage would help in saving neurons, their connections and micro circuits, in conditions where we start to lose them.

I too can smile

Imagine meeting a humanoid robot who can mimic your facial expressions just like humans do. Eva is one such robot. But Eva would smile only after your smile is over. Eva takes time to know what emotion you expressed. To improve this ability and make robots appear more genuine in their responses to humans, Emo has been designed by the same team of scientists at Columbia University that had designed Eva.

Emo has high definition cameras in its eyes so that it can observe the expressions of the humans it is interacting with. It has 26 actuators and magnets under its replaceable face skin so that the facial expressions can be created without missing the finer details of the human smile. 23 motors control its face and three motors its neck to achieve the required expression. Yes, Emo has better hardware than Eva and can smile much better too but what makes it appear genuine?

Videos of humans smiling, were used to train a model for Emo. After this training, Emo can now predict a human's smile 839 milliseconds before the smile comes on their face to smile with them. I don't see a smiling robot taking over the world! Do you?

Reference: Human-robot facial coexpression

Inputs & editing by Ashish Gourav

Sunday 24 March 2024

Python meat, unique bird songs, & invisibility cloaks | Last Week in Science (24th Mar 2024)

Will you eat snake meat?

One of the major arguments of vegetarians, excluding religious reasons, is the impact of raising animals for meat on the environment. With deforestation and 10% of greenhouse gases being coming from the cows raised for beef, water pollution caused by pork and poultry, it sure is better to become a vegetarian. But one cannot even deny the nutritional benefits - proteins and certain vitamins- that come from animal sources. So why not look for alternative sources of protein?

Snake scientists propose that pythons may have the answer to eating meat without harming the environment. For one they are better at converting their food into protein than other animals that are consumed by humans, thereby leading to more protein production. And second they can survive without food for long durations and not lose much of their body mass. Thus, they would need much lesser to be a better source of protein than the existing animals used for meat production for human consumption.

Many parts of the world already consume snakes, so let us wait and see if switching to pythons for our protein requirements is a possibility or not.

Reference: Snake Steak Could Be a Climate-Friendly Source of Protein

The symphony of birds

All bird songs sound sweet to our human ears, but it is not the same for birds. While a lot of song birds sing many different songs, some like zebra finch sing only a single song throughout their life. The female birds, wherein males sing a variety of songs, use this variety as a criteria to select male birds, the more variety would mean greater fitness of the bird thereby increasing its chances of selection by the female. We do not know how a single song in zebra finch can help them decide the fitness of their mate.

Male zebra finches sing the songs that they have learnt in their childhood from their tutor - their father. So, each bird song is going to be unique and male birds sing this song in their adulthood to attract mates. The female birds choose their mate by listening to their song. Until now, we have classified bird songs based on pitch, duration, and loudness - factors that are perceptible to human ears. We do not know how and what features of the song the female birds use to select their mate.

In an attempt to understand this complex communication between birds, scientists recorded songs sung repeatedly, 1000 times, by 49 different male birds. They then used machine learning and artificial intelligence to make sense of this complex data. The different sounds or syllables of the songs were used to understand the complexity of the songs. The researchers found that male birds which produced more distinct sounds - that can be considered as high quality, were chosen by the females. Also, such songs were more difficult to learn as compared to the ones that did not have highly distinct sounds or syllables.

This study needs to be repeated to understand whether the female birds indeed use distinctness of syllables. And also what does the distinctness of syllables, estimated by machine learning, mean in terms of how we classify and understand sound.

Reference: Birds convey complex signals in simple songs

Invisibility cloaks

Credit: Lin Wang and Tak-Sing Wong / Penn State. Creative Commons

We see objects because they absorb certain wavelengths of light and reflect others. The color of the object is decided by the wavelength that it reflects. A material that will not reflect any visible light will be invisible to human eyes. Such anti reflective material coatings are used to coat glass screens and lenses to reduce glare. But the materials that are used to create anti reflective coating isn't suitable to make other surfaces invisible.

Researchers at Penn State University have now synthetically created a material that may someday lead to the creation of cloaking devices - that can make objects or individuals invisible. This synthetic material mimics a naturally occuring substance present on the body surface of leaf hoppers. Leaf hoppers cover themselves with particles called as brochosomes that are football shaped hollow structures with holes evenly distributed on their spherical surface. The function of brochosomes is not fully understood but it is known that their structure, which is of the same dimension in all the insects irrespective of the insects' size, absorbs UV and visible light completely. It is thought that the absorption of UV light makes them invisible to their predators that have UV vision. 

Scientists synthesized a scaled up version of brochosomes by 3D printing which was shown to absorb 94% of the visible light. Studies are underway on improving the production of brochosomes and also manufacturing much smaller versions that will be same in size as the ones in leaf hopper. The potential applications range from better anti reflective coatings for devices like solar cells, encryption technology with the possibility of decoding a message only under a specific wavelength and of course invisibility cloaks.

Reference: Backyard insect inspires invisibility devices, next gen tech

Sunday 17 March 2024

Menopause in females, female mammals larger than males, & non-antibiotics | Last Week in Science (17th March 2024)

Are longer lives to blame for menopause?

Menopause is the loss of the ability to produce children by the human female. We do not know the reason for the evolution of menopause but there is a grandmother hypothesis. It says that because of menopause grandmothers are invested in their grandkids so as to ensure that their genes get passed on beyond their children's generation. The second reason might be the elimination of competition of resources between their own children and grandchildren because both the grandmother and mother won't be reproductively active or in the child bearing phase at the same time. While there is no study done in females that can explain or substantiate the grandmother hypothesis, scientists have studied toothed whales to find an answer.

Menopause is not a unique feature of humans, but other mammals like some toothed whales are also known to undergo menopause. But not all the species of whales undergo menopause. Scientists compared these different species - the ones with menopause vs the others without by looking at their lifespan and fertility. They found that toothed whales that experience menopause have longer lives than the ones who do not. But since it is not possible to go in the wild and check for how long a whale lives or can produce children, so the scientists had relied on whales that were caught by shipping vessels, whales stranded on beaches. They looked at the ovaries of these females to guess for how long the whales would have been actively producing children. So, it seems we might have to wait till we find an answer to the reason of why menopause exists. It is also possible that menopause is just a side effect of long lives of females.

Reference: Whales make waves in the quest to discover why menopause evolved

Non-antibiotics that can act as antibiotics

Antibiotics are medicines that are used to treat infections caused by bacteria. There are other medicines as well which are not antibiotics but have the ability to kill bacteria. This does not mean that they can substitute the traditional antibiotics because these are medicines that are used to treat other conditions. Diabetes medication, non steroidal anti inflammatory drugs like aspirin, antipsychotic medicines are some examples. Although, we know how antibiotics kill bacteria but we do not know how these non-antibiotics work.

Scientists studied 200 non-antibiotics to understand how these drugs interact with bacteria and which genes of the bacteria might be causing their death by a particular drug. What they found was that non antibiotic medicines target the bacteria for killing by following a different path than the antibiotics. This means that the knowledge that we gain from how non antibiotics kill bacteria can be used to develop new antibiotics. During this study, the scientists also found that since the non antibiotic drugs affect the population of the bacteria in the body - mainly the gastrointestinal tract, it may be possible that they contribute towards antibiotic resistance which is when antibiotics are not able to kill bacteria which have become resistant. This particular finding is of utmost importance and needs to be further investigated. Hope the learnings from exploring non antibiotic medicines will help us in combating antibacterial resistance.

Reference: Antibacterial activity of nonantibiotics is orthogonal to standard antibiotics

Are male mammals larger than females?

From the last 150 years, it has been believed that all male mammals are larger in size than females because Darwin said so. Darwin had no proof for saying it. All the studies done so far to look at differences in size of male and female mammals have been biased as they included only a certain type of species, excluding bats and rodents, and relied only on the mean value of the body mass. This current study has challenged the long standing belief of males being larger than females in the mammalian world.

Scientists have now looked at body mass measurements of more than 400 species of mammals. The data that they used for this study included the variance along with the mean values of the body mass. Variance measures how much variation in size exists within a species. The study found that only 45% of the species have larger males than females. And in 39% of the species that were included in the study had no difference in the sizes of males and females. While in 16% of the species, females are larger than males. Thus, although males are larger in most cases when there exists a difference between male and female size in the mammalian world but it is neither universal nor that common as it was earlier thought.

Reference: New estimates indicate that males are not larger than females in most mammal species

Sunday 10 March 2024

Bumblebees & chimps, skin eating baby worms, & electric fish sensors | Last Week in Science (10 March 2024)

Is learning from others our super power?

One of the reasons for success of humans as a species is considered to be our ability to learn from the inventions of others and then build up on it. But it seems this is not an ability that is unique to humans. There are examples of pigeons who improve their flight by learning from each other but it is not as spectacular as what humans can achieve, like bringing a new iPhone model each year or foldable mobiles.

Researchers have now found that such learning can happen in our close relatives - chimpanzees too. When chimps were given a vending machine from which they can get peanuts after doing a task that is simple for us but a complicated maneuver for them. The chimps had to take a ball, open a drawer, put the ball in a slot and then close the drawer. For three months they tried but none of the 66 chimps they tested could figure out how to get the pack of peanuts from the machine. The researchers then trained two of the chimps as to how to use the machine. The other chimps were then made to see how the two chimps got peanuts from the machine. The researches then saw that 14 of the observer chimps learnt how to do this task. One may argue that chimps are smart and are known to make tools so it is not that big a deal.

But in another study, researchers made similar observations on bumblebee. The bumblebees had to remove a block to gain access to another block that when pushed will give them access to sugar. The researchers gave 24 days to bees to solve this puzzle on their own but they could not do so. But when they trained 9 bees and made 15 other bees see them solving and reaching the sugar reward, 5 of these 15 bees also learnt from this demonstration. It seems that learning from others may not be our super power.

Reference: Bees and chimpanzees learn from others what they cannot learn alone

Mystery of baby worms that feed only once a week

More than 20 years back scientists found a type of worm - caecilian- who would feed on the skin of their mother worm. They would do this once a week. It was astonishing because how can these baby worms survive with feeding just once in a week. To solve this mystery, scientists recorded the worm behavior for 200 hours. What they found was the young worms would make clicking sounds which would cause the mother to release a nutrient rich liquid - similar to milk, from its cloaca - opening of the body at the end of the digestive tract that is an outlet for both the digestive and reproductive system. The worms were also moving their heads inside the cloaca to feed.

Other species of this type of worm are known to release milk like liquid to the unborn worms that hatch inside their bodies. But the worms that were studied by the researchers hatch outside the body and feed on their mother's milk.

Reference: Got milk? Meet the weird amphibian that nurses its young

Story of electric fish sensors

Just like bats use sound for locating objects in their surroundings, electric fish use electrical signals to do the same. But unlike bats, these electric fish move in groups. One may wonder how the electrical signals of a fish would not interfere with that of the other fish. And scientists too have been focusing on their studies to understand the same. So, fish keep adjusting the frequency of their electrical signal pulses to ensure that they don't jam the signals of another fish in their shoal. In a recent finding, scientists have discovered that in one species of electric fish - elephantnose fish, the signal of another fish in their group is used to their advantage.

Sensing devices like sonars, radars and some CT scanners use multiple sensors to increase their field of sensing. Elephantnose fish also do the same by using other fish's signals. The information that comes back from the nearby fish helps them to sense a larger area of their surrounding environment.

Reference: Collective sensing in electric fish

Saturday 2 March 2024

Human tail, butterfly wings, & repetitive behaviour | Last Week in Science (3rd March 2024)

Tale of the tail

With the myriad functions the tail serves for organisms that have one, it is still a mystery as to why and how the common ancestor of apes and humans lost their tail.  One of the hypothesis for why our ancestor lost the tail is that the bipedal walking - walking on two limbs was easier without a tail. But a lot of animals have a tail and can still walk on two limbs. Certain AI models for robotics have even shown that a tail actually helps in stability while moving on two limbs. Although, we do not know the why but a group of scientists may have found the how.

Researchers in New York studied one of the genes - TBXT, which is involved in tail development in various species including mice and cats. They found that in apes including humans the TBXT gene is altered in a way that it forms a shorter RNA as compared to the RNA that gets formed from TBXT gene in other primates that have a tail. So, the code of the DNA is first transcribed into an RNA molecule which further forms a protein. A shorter RNA being formed means a shorter protein being formed in apes which could be the reason for loss of the tail. The scientists then introduced this altered TBXT gene of apes in mice to test whether the mice lost their tail. And they indeed lose their tails. I wonder now whether these mice can be trained to walk on two limbs like humans.

Reference: How humans lost their tails — and why the discovery took 2.5 years to publish 

Colors of butterfly wings

As soon as you read Biology in high school, you learn that the genes code for proteins which form via an intermediate molecule RNA. But then we now know that more number of genes code for RNA that never form proteins. This RNA must be doing something. The past few decades have shown that this RNA that is not coding for protein or non coding RNA plays an important role in deciding the formation of other proteins or as to say whether and when a specific gene is active to form the protein. When we talk about visible features and say that genes might be responsible then mostly it is the protein that is being formed from that gene is responsible. But that may not be true in the case of butterfly wing colors.

Who doesn't like looking at butterflies flapping their beautiful wings as they move from one flower to the other? Have you wondered what makes the butterfly have such colorful wings? By studying white butterflies, scientists found that it is not the protein but an RNA that decides whether the color pigments will form or not in the butterfly. This RNA molecule is a long non coding RNA or lncRNA. LncRNAs are known to be involved in many functions in the body and play important roles in the development of many diseases. But the current study is the first example where a visible trait is getting affected because of an lncRNA.

Reference: Surprise RNAs solve mystery of how butterfly wings get their colorful patterns

Beyond the role of glue

Half of the cells in the brain are not neurons but glia. The glial cells have been known to be the supporting cells for neurons till now. An increasing number of studies are showing that glia are much more than being the glue for neurons.

Repetitive behavior or doing an action again and again is present in disease conditions, like moving objects around to be in a specific order as seen in Obsessive Compulsive Disorder, repeated movement of limbs in Huntington's and Autism. A particular protein was found to be reduced in the brain of individuals with these conditions. In a surprising finding, the scientists found that this protein forms not in neurons but astrocytes - a type of glial cells. When they removed this protein from mice then repetitive behavior in the form of excessive self grooming, excessive licking of the water source in the cage, or excessive exploring of a familiar object stopped. Although, they still need to find how astrocytes are controlling neurons and thus the repetitive behavior, but this finding may soon lead to a better understanding of diseases like OCD and autism. 

Reference: Non-neuronal brain cells modulate behaviour

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.

Sunday 28 January 2024

Ants & lions, immune system & ageing, stress & bacteria in the intestine | Last Week in Science (28th Jan 2024)

The ants and the lions

The old moral story of how small ants can fight off an animal as huge as an elephant was true in the forests of Kenya until big headed ants started showing up. Scientists observed that the big head ants started to kill the native acacia ants which would have saved the acacia trees from being eaten up by the elephants.

You must be wondering how elephants getting more food to eat can affect the lions.

These acacia trees provide hiding spots to lions for hunting zebras. The absence of acacia ants, increased grazing of acacia trees by elephants that decreased the tree cover. Scientists at Wyoming University studied number of zebras in areas where big head ants had invaded comparing it to areas where they had not invaded. They also looked at how many zebras got killed in these two different regions. They also tracked the movement of lionesses in these different regions by bugging them with GPS.

After three years of tracking, the result was as the trees started getting less dense, creating more open space, the lions had trouble in hunting zebras. So, the lions started hunting buffaloes. But how can that be a big deal? For one it takes lions more energy to hunt buffaloes and at times the lions get killed in the process. Second, the increase in zebras could cause unexpected changes to the existing ecosystem of the forests in Kenya.

This study is a beautiful example of how one small change in the ecosystem can have big effects. 

Can we use the immune system to slow ageing?

Our immune system have a specific type of cells called as the T cells which are trained to recognize specific cell types - pathogens or infected cells. With the recent advances, these T cells can be trained outside the body to recognize other types of cells - like cancer cells. These trained cells are called as CAR-T cells for chimeric antigen receptor T - cell. These T cells recognize specific molecules that are present on the surface of a specific cell type.

The aged and defective cells are called as senescent cells are the ones that have stopped growing and dividing because of damage. These cells usually release signals to call immune system to destroy them and are important for preventing cancer and causing healing after injury. The senescent cells increase in different tissues as we age. Their removal becomes less effective because of the decline in the immune system as we age. In the recent study, scientists at Cold Spring Harbor Lab generated CAR-T cells to recognize aged cells of mice. What they found was when these CAR-T cells were introduced in aged mice then they prevented some of the diseases that come with ageing or because of consumption of high fat diet. These mice were also physically more active after this one time treatment.

But it still remains to be seen whether it can prolong life and whether we can use such an approach in humans.

Stress and the bacteria in the intestine

We all have heard examples of how stress can upset one's stomach. In severe cases, a disease called as Inflammatory Bowel Disease (IBD) is seen with stress that persists for a long time - called as chronic stress, which causes swelling of the intestines, stomach pain, and diarrhea. 

In the recent study, scientists at China Pharmaceutical University found that when mice were given chronic stress, for 2 weeks, they could not produce enough cells in their intestines to protect from infections and so causing swelling or inflammation. A specific type of bacteria of the Lactobacillus genus was found to be increased in their gut. These bacteria produced a chemical - indole-3-acetate (IAA). This chemical did not let the stem cells of the intestine to form the cells that would have protected the gut from infections.

What is interesting is scientists also found Lactobacillus and IAA in feces of humans who have depression. The scientists could treat the mice by giving a chemical called as alpha ketoglutarate. But it will still take time to see whether the same treatment would work in individuals suffering from inflammatory bowel disease or not. 

The scientists are still seeking answers to how the brain affects the bacteria in the intestines. These answers will help in understanding and treating many diseases that happen because of stress.

Saturday 20 January 2024

The tail wag, the sick chimps, reversing memory loss | Last Week in Science (21st Jan 2024)

The tail wag

Can't get enough of your dancing dog with their tail wagging on seeing you? Do you wonder why they wag their tails?

In a recent compilation of existing studies, researchers have made some interesting findings. Tail wagging is seen in many other animals like wolves for communicating. In the wild, wolves may show a sign of submission to a more aggressive wolf by tugging their tails between their legs or moving it slowly, which is also true for dogs. Dogs not only wag their tails more often than wolves but also show an asymmetry when it comes to their preference towards the object that they are wagging their tail after looking at. When they want to approach towards an object then their tail wags more towards the right side while it is towards the left when they want to move away from the object. The speed of their tail movement does help in distinguishing whether they are happy or aggressive.

But we still do not have clear answers to whether they feel happy and so less stressed after they dance with their tails wagging fervently, how does their brain control the movement of their tails and is this a behaviour that they can control voluntarily.

The sick chimps

It's not only animals who transfer disease causing microbes to humans but the reverse is also true. Remember how you were asked to stay away from your pets if you caught COVID-19. The cases of cheetah and deers getting affected of COVID-19 were also reported, which created a fear of SARS-COV2 evolving in these animals into more deadly forms. What we overlook is how we can affect the different species especially of apes like chimpanzees and gorillas who are closely related to us. There have been disease outbreaks in the wilderness of sanctuaries because of microbes that may not harm humans that much but have been deadly for the apes. The situation is more pertinent because many of these species have such low numbers that we cannot afford to lose them to such infections. 59% of deaths of these apes which had a known cause were because of infections coming from humans.

Transmission from tourists who do not follow safety guidelines of wearing masks and not going close to the animals are one of the causes.

A study that was conducted in Kibale National Park, Uganda traced the transmission from scientists working at the Park who had young children studying in schools. By testing children, their parents and the chimpanzees' stool samples the link was established. This brought to light the unhygienic conditions of the schools where these kids used to study and the initiation of Happy Children Happy Apes program with measures like creating awareness about infections in children. It is hoped that making scientist, tourists, Park officials, and nearby residents aware would help in keeping the apes safe. 

Reversing memory loss

Athletes like football players often get hit by the football on their heads. Multiple mild hits on the head can cause memory loss or what is known as amnesia. It was earlier thought that such a memory loss is because of the death of neurons in the brain, an event that cannot be reversed. But in a recent study scientists have shown that this isn't true. 

They gave multiple mild head injuries to mice to see the effects on its memory. These mice had neurons tagged in a manner that the scientists can switch them on and off. What they discovered was it is the connections between the neurons that are responsible for remembering a memory get affected and when the scientists switched on the specific neurons they could reverse the memory loss seen after the head injuries.

Although, we are still too far from using this finding in humans but what gives hope is the possibility of reversing memory loss in instances of mild brain injuries.