Feature: How Evolution Can Explain Allergies

Every summer, when I return home for my vacations, I am hesitant about eating food at roadside stalls because, you know, who knows how unhygienic the food there is? In a role reversal that I still find amusingly ironic, my mother would accuse me of being wimpy and shove a plateful of food into my hands. Her logic—if we are over-protective of our immune systems, they will ‘forget’ how to respond when hit by a major infection. Blood them in battle, she said.

I’m still going to hold off from the delicious and teeming-with-microbes sugarcane juice on Indian roads, but as it turned out my mother was on the right track. A variant of her statement does apply in the case of allergies in what has been proposed as the ‘Hygiene Hypothesis’. Did you know that the incidence of autoimmune diseases (allergies being a prime example of these) is much higher in industrialized countries? Exposure to infectious agents in childhood primes your immune system for a more effective immune response as you grow up. Conversely, an extremely sanitized environment (often seen in industrialized countries) during childhood can make your immune system weak, unprepared to face infections and respond to harmless molecules that then become allergens.

Evolutionary Mismatch

How, and why does this happen? The answer lies in an ‘evolutionary mismatch’. Our bodies evolved in an environment which is very different from the one we live in now.

Let’s travel back in time for a little bit. In the first stage of human history, members of our species were hunter-gatherers. Our immune systems were constantly being exposed to a host of microbial organisms and worms. Around 12,000 years ago, we started settling down and took to agriculture. We continued being exposed to microbes, and in fact the sedentary lifestyle led us to being exposed to them for longer periods and increased human-human transmission. And then came the Industrial Revolution, bringing with it sanitation, vaccines and the beginning of the world as we know it. Many of the organisms that our ancestors encountered on a daily basis are now depleted from our present-day environment.

[Image Credit: ucla/ Nature Immunology]

‘The Old Friends’ Hypothesis’

We have grown up in the industrial age, but our immune system has evolved over centuries in the first and second stages of human history. Microbes and worms were so omnipresent that our immune systems learned to tolerate their presence in the body if they were harmless. Reacting to an infection is costly for the body, as we know from the all-pervading weakness we experience after a fever. A wiser route for the immune system was to just let the microbe exist, and simultaneously, the worms evolved to release certain molecules that would down-regulate certain components of the human inflammatory system. In the current environment, our bodies do not contain the micro-organisms that regulated our immune system. Our immune systems thus rise to inflammatory baits in a heartbeat.

It’s still a hypothesis, but there’s plenty of evidence that supports it. Guts of children with allergies have been found to have fewer numbers of a bacterial species called lactobacillus. Another study in Argentina showed that people with fewer worms called helminths have fewer incidences of multiple sclerosis (MS).

Our bodies are thus not adapted to the environments we live in, leading to this kind of a mismatch. In context of public health, it is not feasible to think of returning to the environments of our ancestors, nor is it feasible to think of infecting allergic patients with 50 hookworms that would downregulate the immune response. However, learning more about the symbiotic  mechanisms between our ‘old friends’ and our immune systems could help design more effective therapies towards autoimmune disorders.

Sources:

Microbes, immunoregulation and the gut

Old Friends Hypothesis

How Parasites can trick your immune system

Could Your Genes Tell You Why You Hate Cilantro?

The next time you make a face at the cilantro (coriander in certain parts of the world) on your plate, you can blame your genes. A genetic component for the intense dislike of cilantro has been found.

Before you get outraged by the thought of studies performed on culinary preferences, responses to cilantro has been thought of as interesting for quite a while. There are polarizing reactions to it, with some people comparing its taste to soap. On the other hand, it continues to be used generously in South Asian and Latin American cuisines. This even prompted the New York Times to publish an article called ‘Cilantro Haters, It’s Not Your Fault’.

The distinct flavor of cilantro is because it contains a class of molecules called aldehydes. It was thus hypothesized that differences in proteins that can detect these molecules—called receptors—could be responsible for the strong variation in response to the herb. Now, researchers at the sequencing company 23andMe have used genome sequences of 14000 Europeans to hunt out a genetic cause.

Cilantro (also called coriander) is commonly used in many cuisines across the world. Different populations, however, often have sharply contrasting perceptions of its taste.

‘Crowdsourcing’ Data

This research was part of a larger group of projects under 23andMe, which could be called crowdsourcing. In this process, the company sequences people’s genomes and provides genetic analysis. Clients willing to participate in 23andMe’s research are then asked to fill up a questionnaire about various traits that might be genetic, for instance, whether they think cilantro has a ‘soapy’ taste (another example could be eye color). The company then uses this data for their analysis. In this experiment, they found that one varying position in the genome—called a single nucleotide polymorphism (SNP)—was found to be associated with the way people think cilantro tastes. To put it another way, people who detest cilantro were much more likely to have one version of this SNP as opposed to people who like it, who are more likely to have another version.

Having found this SNP, they realized that it lies within a cluster of 8 olfactory receptor genes, genes involved in the perception of smells. This could thus be a strong candidate gene responsible for the divisive response to cilantro.

However, this SNP only explains a very low percentage of the variance in the trait. What does this mean? Ideally, we would expect to be able to predict a person’s response to cilantro based on the SNP she has. However, that is not the case, only 1.5% of the variance in the trait can be explained. This could be because there are multiple genes that act together in determining cilantro response (and they have only managed to capture one of them), or that only a small amount of cilantro response is actually genetic. Thus, in the latter case, even a significant SNP cannot significantly affect cilantro detection. This study was only performed on a European population, studies capturing a greater diversity could yield further answers.

You can read about this research here.

Beauty and the Beak, How an American Bald Eagle’s Life was Saved

It is one of those stomach turning stories showing the ignorance of mankind that turns into a heartwarming story showing the best of mankind. Meet Beauty, pictured below, an American Bald Eagle who was the unfortunate victim of the cruelty of man. She was rescued in Alaska by Janie Fink of the Raptor Chapter located in St. Maries, Idaho. Someone had shot the top part of her beak off and left her to die. The damage was so extensive that officials gave her no chance of survival. However, Ms. Fink refused to give up on her and the story that follows is amazing.

Beauty
Beauty,an American Bald Eagle, pictured with her damaged beak (Courtesy of Kinetic Engineering Group Portfolio)

Beauty’s damage basically crippled her. Her beak was broken all the way back to her sinus cavity. She was emaciated and couldn’t drink or eat on her own. In fact, the Raptor Chapter folks had to feed her with liquefied food through tubes in order to get her strong enough to eat more solid food. Her injury was so debilitating, they described it as trying to eat food with a single chopstick. Beauty’s luck however, was about to change. On a fateful day when Janie Fink was making a raptor presentation, she ended with the riveting story of Beauty. This story fell on the ear of Nate Calvin, a Mechanical Engineer and founder of Kinetic Engineering Group. It just so happened he had brought his daughters to see the raptors that day and he was compelled to help Beauty get a new chance at life. Against all odds, and many naysayers, Nate and his team used highly advanced CAD software, typically used for aerospace engineering, to develop a prosthetic beak. This was a very complicated design that was a first of its kind. With the help of Nate’s personal dentist, he was able to fit Beauty with a prosthetic beak that actually permitted her to drink water on her own again. See the embedded video below for more details.

[Video Link]

[Beauty and the Beak from Keith Bubach on Vimeo.

Beauty will probably never be able to live in the wild, but hopefully this prosthesis will allow her a second chance at life. If you would like to contribute to Beauty’s cause, you can make donations to the following:

The Raptor Chapter
PO Box 585 St. Maries, Idaho 83861
208.245.1367

Email: [email protected]

or

Make checks out to “Birds of Prey NW” and mail to:

Birds of Prey NW
PO Box 3507
Coeur d’Alene, ID 83816

You may also make donations online using PayPal or VISA/MC, click here.

For more information, visit Kinetic Engineering Group’s website or Birds of Prey Northwest’s website.

Scientists Discover How Our Brains Age

We all know we acquire grey hair, declining senses and feel our body changing as we age, but how do our cells—those microscopic components that make up our body—change as we grow old? Biologists have known the answer for most cells in our bodies. As cells age, their DNA gets accumulatively damaged over time, and this DNA damage leads to a ‘senescence pathway’ via a DNA damage response (DDR). This DDR permanently arrests any further division of the cell and leads to changes in the expression of many genes (including many inflammatory genes) and also leads to dysfunction of the cell’s respiratory machine, the mitochondria. It doesn’t stop here. The DDR induces the damaged cell to release a host of toxic ‘reactive oxidative species’, which then affect the entire tissue.

Images showing how the brain ages
These fluorescence scans from brain cells show the difference in molecular markers (one marker in each row) between young brain cells (columns 1 and 2) and old cells (columns 3 and 4). The difference between columns 1 and 3 gives us markers whose activity increases substantially in aging cells. [Image Credit: von Zglinicki et al, Aging Cell]
However, this sequence of events has only been observed in cells that have the ability to divide—a category that includes most cells in the body, but leaves out the cells of the brain, the neurons. Researchers at Newcastle university have recently studied brain cells of mice to study how they age, and they have found the same senescence pathway active in the aging brain. To study this, they isolated cells from various brain regions of mice and looked for the presence of ‘molecular markers’—in this case, molecules that would indicate that a certain pathway or gene was activated. For instance, Interleukin-6 was a protein molecule that was used as a molecular marker for the inflammation found in aging cells. Using many such markers, they found that the exact senescence pathway previously found in dividing cells was also active in neurons.

Until now, it was assumed that aging pathways in the brain would be different, but this research shows that this is not the case. Using this information about aging neurons gives us an avenue to better understand the mechanisms of age-related mental disorders such as cognitive decline.

You can read about this research here.

Scientists Create First Light Controlled Nano-Switch

The drive to make faster and faster computers just got a huge optical jump! University of Pennsylvania researchers have made a quantum leap in designing new-age gates for use in new age computers. These gates are controlled by light!

Computers of today are made out of gates that are switched on and off by electrical signals. The crucial speed involved in the switching speeds of these gates is the velocity at which electrons (or other charge carriers) travel inside the substrate that make up the gate. In other words, how fast you can switch a gate on and then off and then on again depends on how fast the electrons feel the changing electric field and travel back and forth. All of this can be greatly accelerated if we use light signals and not electric ones!

Light Switches!

So here is the first photonic switch, all made out of cadmium sulphide nanowires. The team of researchers consists of an associate professor Ritesh Agarwal and graduate student Brian Piccione, from the Department of Material Sciences, Pennsylvania University.

They are carrying forward their earlier research finding, when they found that cadmium sulphide (CdS) nanowires is the perfect substance on which to attempt such a thing. Cadmium sulphide exhibits very strong light-matter coupling. This simply means that there exist mechanisms within the substrate that can control the way light behaves within the material.

How they did it

What they did was cut a gap in a CdS nanowire. Light was then shone on one of the sections. This light is perfectly transmitted down the length of the nanowire. Now, the team shone another light on the second part of the nanowire. This, believe it or not, cuts off the light that was already going through the nanowire. This phenomenon is called destructive interference. So now, you have a gate which you can turn on or off by shining light on the second part. All you need to do, in principle, is to measure the intensity of light coming out the second part of the wire.

And that’s it!

This is a basic switch. With switches you can make gates. With gates you can design a computer.

One of the basic types of gates is the so called NAND (Not AND) gate. The NAND gate can be used to construct any other gate. A NAND gate returns a high signal (‘1’) if either or both of the inputs is zero, and zero if both inputs are one. The team has built such a device using two CdS nanowires.

The paper appears in Nature Nanoscience: http://www.nature.com/nnano/journal/vaop/ncurrent/full/nnano.2012.144.html

Speaking Out Your Fears Helps You Face Them

If the results from a recent psychological experiment are to be believed, the saying ‘’Face Your Fears’ might just have to be changed to ‘Blurt Your Fears’. Researchers at the University California, Los Angeles, have found that saying your fears before facing them actually reduces the fear itself.

Fooling Yourself into Being Less Scared

Similar to other actions that intentionally regulate emotions, such as distraction, it has been increasingly believed that giving an emotion a label, either in verbal or in written form, can help downregulate it. This downregulation is not merely at a superficial level. Brain regions that are involved in emotional processing are actually found to be less active when an emotion is labelled as opposed to when it is not.

Speaking out your fears may help you face them. [Image credit: learnamericanenglishonline.com]

Is Labeling One’s Fear Better than Distracting Oneself or Rationalizing Away the Fear?

Scientists decided to apply this in a real-world context, by testing how different groups of people could change their fear of spiders (arachnidophobia). Participants were divided into four groups—each of which had to face a tarantula. The first group, called the ‘’affect labeling’ group, had to state their fear before they went closer to the spider. The second group, called the ‘reappraisal’ group, had to vocalize something neutral (and definitely not negative) about the spider and their emotions towards it, something that would prime them to think less negatively about how they approached the spider (for example, “Looking at the spider is not dangerous for me”). The third group was the ‘distraction’ group in which participants had to describe furniture in their room. Participants in a fourth ‘control’ group did not vocalize anything. Participants from all groups were again exposed to the spider a week following this test.

Our Bodies Show Different Responses From Our Minds

The skin conductance response test (SCR) was used as one indicator of emotional arousal while approaching the spider, so as to reduce subjectivity. It was found the the degree of this arousal (representing fear) decreased much more in participants of the ‘labeling’ group as opposed to all other groups, i.e., participants who had stated their fear of the spider showed the greatest reduction in this fear response a week later. Interestingly, none of the participants said they felt less scared when they were asked to self-report their fear, it was just that their bodies responded less…fearfully.

The authors propose that this result is similar to those achieved by being in a state of mindfulness, which is also associated with reduced activity in the regions of the brain involved in emotional response.

Thus, speaking out your fears might just be all you need to face them more easily. You can read the published article on this experiment here.

One Half Million Mile Solar Filament Observed

NASA’s Solar Dynamics Observatory (SDO) has observed an incredible whip-like filament extending high above the sun’s surface. Pictured below, the filament measures one half million miles long. To put that in perspective, the earth’s circumference at the equator is approximately 25,000 miles.

Whip
Credit: NASA/SDO

A solar filament is tethered to the sun’s photosphere and jets out towards the corona. It is a cooler material and thus the contrast can be observed. Below, you can see a video from NASA’s SDO which shows the incredible phenomenon.

[Video Link]

The Solar Dynamics Observatory was launched back in February of 2010. Since the time of its launch, the SDO has brought back stunning video and photos of never seen before views of our Sun.  According to NASA the purpose of the SDO is as follows:

The Solar Dynamics Observatory (SDO) will be taking a closer look at the Sun, the source of all Space Weather. Space Weather affects not only our lives here on Earth, but the Earth itself, and everything outside its atmosphere (astronauts and satellites out in space and even the other planets).

Space weather is a serious issue for astronauts and satellite developers. Because we enjoy the benefits of being surrounded by Earth’s atmosphere, we only have to worry about little things sunburns and using sunscreen. Outside the confines of our atmosphere though is a much larger danger. Extreme radiation coming from the Sun’s surface can be perilous to our astronauts, so getting a better understanding of this is critical for their safety. Communications satellites are not exempt from solar related problems either.

For more information about the SDO mission, visit NASA’s website at http://www.nasa.gov/mission_pages/sdo/main/index.html.

Curing the Inability to Smell in Mice

‘Anosmia’ is the inability to smell, which is more harmful than it sounds, primarily because it could lead to a tendency to eat less, often leading to starvation and weight loss in mice. Anosmia can be caused by a number of factors, one of which is ciliopathy—when there are problems with the tiny protuberances on sensory cells called cilia. Among other cells, these cilia are found on the neurons that function in odor perception, and serve as ‘antennae’.

Image Credit: University of Michigan Health System

Scientists at the University of Michigan have treated mice that had genetic defects in a protein IFT88, which causing them to have no cilia across the body. They injected a common virus into these mice carrying DNA with the normal version of this gene. As the virus inserted itself into the genomes of these mice, they started producing cilia and their feeding patterns were found to change considerably. Moreover, the mice showed a 60% increase in body weight. “By restoring the protein back into the olfactory neurons, we could give the cell the ability to regrow and extend cilia off the dendrite knob, which is what the olfactory neuron needs to detect odorants,” says postdoctoral fellow and first author Jeremy McIntyre, Ph.D.

This is only a starting point for ciliary disorders, primarily because a mutation in IFT88 in humans is fatal, and does not cause the same defects as in mice. Thus, though this research has some way to go before it could be extended to humans, it shows promise in treating olfactory diseases that are genetic and due to malfunctioning cilia. Moreover, cilia perform important functions in diseases that aren’t just related to smell perception. Polycystic kidney disease and a disease called retinitis pigmentosa in the eye also result from a problem with the cilia.

You can read about this research here.

Good at Maths? Your Brain Communicates Better

Have you ever wondered why you are decent at Mathematics? Well, it isn’t just because of wonderful Mrs. Gunderson who taught you in high school. It’s because certain parts of your brains have more ‘wires’, or neurons, connecting them.

Division of Labor—Recognizing Quantities and Computing Are Done by Two Different Halves

There is a region of the brain called the parietal cortex  that performs the role of numerical cognition. Additionally the left and the right halves of this cortex perform different parts of this activity. While the right parietal cortex primarily processes quantities, i.e. this half confers an intuitive sense of the magnitudes of numbers and their relationships, the left half performs numerical operations. What has remained unknown is how these two halves work together while we perform arithmetic that requires the functions of both halves.

The parietal cortex is the outer art of the parietal lobe. [Image Credit: thebrain.mcgill.ca]

Greater Neural Crosstalk Improves Arithmetic Ability

Researchers at the University of Texas and the University of Michigan used functional MRI to image the brains of 27 adults and found that the neural connectivity between the left and the right parietal cortex increased in each of these individuals when they were given mathematical problems to solve. Individual participants who were faster at performing the arithmetic tasks (subtraction in this case) were found to have greater connectivity between the two halves, whereas no such correlation was found between speed of computing and activity within each half. This implies that the speed at which we compute depends to some extent on how fast numerical quantities and operations transmit between the two halves of the cortex.

Before some of us rush to place the blame for our mathematics grades on our genes, it should be noted that the brain is remarkably plastic. The more we work on something, the better the brain becomes at it. The neural structure of our brains might be a result of extensive mathematics practice rather than inherited. This study therefore reflects the mechanism, and not the cause of arithmetic ability. Thus, you might just have to thank Mrs. Gunderson for your enhanced neuronal structure after all.

You can read about this research here.

Mother-in-Law, Daughter-in-Law Conflict Led to Evolution of Menopause

One evolutionary quandary that has plagued biologists is the existence of a menopause in women—the time after which a woman loses her ability to reproduce. Why would females of a species stop reproducing? What is the evolutionary advantage to this? Wouldn’t it be better for a woman if she could keep producing offspring and thus propagating her genes for as long as possible? In fact, menopause is relatively uncommon in animals, though it has not been widely studied.

Grandmothering Effect and Other Hypothesis

One hypothesis that has been proposed to explain this is the aging effect. As women age, they are more likely to develop mutations that they pass on to their children. Stopping their ability to reproduce could help protect the species from defective mutations. Another hypothesis is the ’Grandmother effect’. If older women use their resources to help bring up existing off-spring instead of creating new ones, the additional resources given to a child increases its fitness.

A research team has used data from a pre-industrial Finnish population to test these hypotheses. Since the 17th century, the Lutheran church has collected a register of all births, deaths and marriages in Finland. The researchers had access to three generations of 5 Finnish populations.

This age-old conflict runs deep enough for evolution to have acted upon it! [Image Credit: towntopics]

Mothers-in-Law Compete with Daughters-in-law, But Not With Their Daughters

Their most interesting result was that when a mother-in-law and a daughter-in-law had children within two years of each other, their off-springs had significantly smaller lifespan by up to 66%. This suggests that competition between in-laws have led to menopause evolving as an adaptation. On the other hand, when a mother-daughter pair had children within two years of each other, no reduction in children’s ages were seen.

A woman shares no genes with her daughter-in-law, and her grandchild only shares 1/4th of her DNA as opposed to her child (which has ½ of her DNA). Thus, there is no co-operation between the two during child-rearing leading to reduced fitness of all the off-spring. It is interesting to note the contrast when mother-daughter pairs bear children simultaneously and show no competition. The authors suggest that in-laws fought over resources for their children instead of co-operating as mothers and daughters might do.

Modeling this data, the authors of this research have proposed a combination of factors that lead to the evolution of menopause. The first is the grandmother effect, and the second is the avoidance of reproductive conflict between mothers-in-law and daughters-in-law.

You can read about this research here.