Category Archives: Issues in Science

Terminating Species for the Greater Good

Have you ever wished for an annoying species to disappear off the face of the Earth? Do some species seem to exist just to cause misery for the rest of the animals on this planet?

If you answered “yes” to any of the questions above then you are in luck! Humans have invented a clever way to get rid of pest populations. It is called the Sterile Insect Technique (SIT). This technique has existed since the 1950s and was pioneered by Dr. R.C. Bushland and Dr. E.F. Knipling. As you can tell from the diagram below, the concept of this technique is very simple. Basically, nuclear radiation is used to make the male species of the pest you are targeting infertile. Then these males are released into the wild. The wild females cannot detect that the males are infertile so they will still mate with each other. After mating, the females will lay their eggs but the eggs will never hatch because of the mutations the radiation causes.

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The Sterile Insect Technique (SIT) involves releasing sterile males into the wild. The sterile males can still mate but no eggs will be fertilized. Credit: igtrcn.org

Here is a video that does an amazing job of introducing SIT.

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Credit: FAOVideo

You may be wondering if humans should be playing God but SIT is currently safer than using conventional means such as pesticides. With pesticides, it is not just the pests that suffer but everyone else. Helpful bugs such as butterflies and ladybugs can be harmed. Pesticides also ruin the environment by contaminating soil, water, air, and non-target plants. Even you can be harmed since pesticides easily stick to food products and are hard to get rid of. It is estimated that one million people worldwide per year die from pesticide-related causes.

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SIT is safer compared to pesticide use. Credit: Wikimedia Commons

Another reason the Sterile Insect Technique is beneficial is that it can exterminate pests that can’t be targeted by pesticides. These pests torment livestock and humans. The first species that was experimented on using SIT was Cochliomyia hominivorax, a parasitic fly known as the screwworm fly. Unlike normal parasitic maggots which eat dead flesh, screwworm maggots only eat the living flesh of warm-blooded animals. If you’re wondering why the flies are called screwworms, that’s because if the maggots are disturbed, they will “screw” themselves deeper into the flesh. This causes severe injuries and death in livestock. Thankfully, the U.S. has managed to officially eradicate this nightmare in 1982 using SIT.

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The adult form of the screwworm fly. Credit: Wikimedia Commons

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The larva form of the screwworm fly. A wound can contain hundreds of larvae. Credit: USDA

Although this technique is very effective and safe, there are still limitations such as being expensive and requiring high levels of training and security. In the future, as technology improves, Sterile Insect Technique may become reliable enough to replace pesticides.

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A modern-day example of STI being used to eradicate mosquitoes. Credit: TheLipTV2

 

-Bowen Zhao

On immortality: a very human desire

If presented with the fountain of youth, would you drink?

People have entertained the idea of immortality across time. Greek mythology tells of the phoenix, a bird capable of rebirth. The prominence of comics as a publication medium early in the twentieth century gave rise to a slew of superheroes capable of super-regeneration and longevity, like Superman and Wolverine. Even Lord Voldemort [SPOILER: highlight to reveal] went through the trouble of creating seven horcruxes to secure a strong hold of the living realm. Why are we fascinated with the concept of immortality?

The motivation to discuss immortality is probably related to people’s natural aversion to death and aging. There are plenty of cosmetic products and procedures that generate a lot of revenue by reversing the effects of aging, such as Botox. But what if instead of merely combating the symptoms of aging, you could eliminate it completely?

Certain examples of non-aging exist in nature. Hydras have been observed to not age. While not quite immortal, lobsters have shown to not be strongly affected by age. What can we learn from these organisms?

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In DNA replication, DNA polymerase takes up a short space on the sequence that it doesn’t copy, like painting itself into the corner of a room. Image from ClipartHeaven.

At the ends of our DNA strands are sections called telomeres – repeats of nucleotides that prevent degradation of the gene as it replicates over time. Every time a cell divides, the telomeres get shorter. After many replications at a point called the Hayflick limit, the telomeres reach a critically short length and the cell stops dividing. In a way, telomere length is like a biological clock that can be used to determine lifespan.

Cells also produce an enzyme called telomerase, which adds nucleotide bases to the ends of telomeres. However, the rate of telomerases’ repair of the telomeres is overcome by the rate of cell division, so telomeres continue to grow shorter and the cell ages.

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Telomerase. Here, “senescence” means “old age”. Images from the National Institutes of Health.

So does the answer to immortality lie in telomerases? Not quite. High telomerase activity is detectable in more than 90% of malignant tumours. The action of telomerase can provide cells with the capacity to infinitely replicate – a defining factor of tumour cells.

So where does this bring us? We aren’t any closer to living forever, but average life expectancy has risen over time, owing to advancing medicine and lower infant mortality rates. Still, it is just as interesting to ponder how one might spend lottery winnings as it is amusing to think about what one would do with unlimited time. Perhaps the search shouldn’t be for biological immortality, but to leave an immortal legacy. As A. A. Milne had said, “I suppose that every one of us hopes secretly for immortality; to leave… a name behind him which will live forever in this world.”

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“Life Expectancy at Birth by Region 1950-2050” by Rcragun from Wikipedia.

– Trevor Tsang

What triggers Allergies?

 

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Some of the things that we’re allergic to – such as peanuts and pollen, for example – carry compounds that resemble proteins found in parasites. It is found that allergic reactions are actually miscommunicated immune responses: For our own protection, our bodies produce antibodies, which attack similar but harmless compounds. The action of an antibody on a harmful compound can be described through the following video:

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Various environmental and food proteins called allergens are recognized by an immune system antibody called immunoglobulin E (IgE). This part of the mammalian immune system is thought to have evolved as an additional rapid response mechanism to combat parasitic arthropods and worms called helminths. If IgE-mediated immune responses evolved to provide extra protection and not to cause allergic reactions,  then environmental allergens such as pollen should share key molecular properties with the parasite antigens that are specifically targeted by IgE in infected humans.antibodz

To test this, a team led by Nidhi Tyagi from the EMBL-European Bioinformatics Institute identified epitopic-like regions in 206 parasitic proteins and as the first example, it was found that a plant protein (BetV1) has similar binding sites for anti bodies, as it is found for allergens such as pollen in a worm. This confirms that the immune system targets allergens (Both plant protein and harmful parasites) via IgE antibodies and causes immune responses which fail to differentiate between useful and harmful compounds.

Their research also helped them to list 2,445 parasite proteins that show significant similarity in both sequence and structure with allergenic proteins, which can cause immune response against useful proteins. The research team then measured antibody responses in blood collected from 222 people living in the fishing village of Namoni on the shores of Lake Victoria in Uganda. These community members were suffering from schistomsomiasis which is caused by the worm Schistosoma mansoni(pictured below). The blood was collected immediately before anti-schistosomiasis treatment and five weeks afterwards.

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It turned out that a plant protein called BetV1 – the commonest allergen in pollen – is a target of IgE in humans infected with schistosomiasis.

Tyagi’s research adds to one of those definitions: environmental and food proteins that are similar to those parasite proteins against which IgE is an observed marker of protective immunity. Defining allergen-like molecules in parasites and understanding their link to the unregulated IgE response, will help with the discovery and design of molecules for future treatment of allergic conditions.

-RikulThapar

Crossed Legs, Health Risk or Not?

How do you usually sit on chairs? Sitting cross-legged is one of my unchanging habits because I feel very comfortable sitting like this. Even now, I have my legs crossed! Is this really harmful to us? Many say crossing legs can lead to numerous health problems even if it may seem harmless. Commonly known consequences of spending long hours with legs crossed are effects on blood pressures and heart, varicose veins, and blood circulation. Check the video below for brief overview.

Credit: Abilhail Abihu

According to the study in 2007, sitting with crossed legs at knee increased blood pressure, whereas with crossed legs at the ankles didn’t result the same. In the study, 50 healthy volunteers and 53 patients with hypertension, abnormally high blood pressure, participated and randomly allocated. Seated blood pressure was measured with their legs in three different positions; one with feet flat on the ground and two with legs crossed differently. During blood pressure measurements, crossing legs increased systolic and diastolic blood pressures in patients with hypertension. In contrast, healthy volunteers had an increased systolic blood pressure, and a little effect on diastolic blood pressure. Blood pressure was higher when seated legs crossed, but it was a temporary increase.

Varicose veins, enlarged veins that are visible through the skin due to increased blood pressure, appear commonly in legs and feet. Age, genetics, obesity, gender, and pregnancy are all risk factors. Dr. Mohmmed Moursi, an UAMS vascular surgeon, indicated that crossing legs isn’t the major cause of this vascular problem. Instead, they result from an intrinsic problem inside the veins. Another common belief he mentioned was that standing for long hours is another cause of varicose veins. Nonetheless, standing may magnify the existing problems with veins but shouldn’t directly cause them.

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Normal Vein (left) and Varicose Vein (right). National Heart Lung and Blood Institute via Wiki Commons

Many say crossing legs can cause problems for blood circulation but there aren’t many evidences supporting that. Not only sitting cross-legged, but also staying in one position for too long can lead to the numbness in feet. The sensation is from sitting legs crossed which created pressure on the peroneal nerve, located in the back of the knee. People generally change their position when they begin to feel uncomfortable. The recent study in Korea found that sitting legs crossed wasn’t the cause, and in fact, sitting sedentary positions for long time did affect.

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Women sitting with legs crossed. Ion Chibzii via Wiki Commons

Perhaps, avoiding sitting stationary or improving postures when seated are the solutions. In fact, good posture can improve muscle function, blood flow, lung functions, and mental health. Surprisingly, recent studies showed good posture affects intelligenceimproves abilities to remember, and protects from having back-problems. Thus, sitting with legs crossed isn’t the direct cause but sitting in the same position for long periods of time can be. Exercising regularly, stretching, taking walks in between, and even focusing on sitting up straight can help one change one’s sedentary lifestyle. 

By: Josephina Kim