BioQuakes

AP Biology class blog for discussing current research in Biology

Tag: Taste

Sour Science!

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On November 5, 2023

In Student Post

Have you ever enjoyed an orange and wondered what causes its amazing citrus flavor? Well, scientists have recently discovered the origins of citrus’s sour taste. 

Scientists have recently discovered the origins of citrus fruits like oranges and lemons. In their study, they discovered a specific gene, PH4, that influences the fruits’ taste by regulating the fruits’ citric acid levels. Additionally, the researchers traced the fruits’ evolutionary journey from the Indian subcontinent to south-central China over millions of years and discussed influences that environments may have had on the citrus.

There are many reasons why these fruits evolved the way they did. One reason discussed in the article is human interference through selective breeding. Thousands of years ago, humans selectively bred certain types of citrus for food and medicinal purposes. Another reason they might have evolved to have more citric acid is to prevent bacterial infections. Bacteria, generally, prefer neutral environments with a pH of about 7. o.  Citric acid has a pH of about 3.2. Therefore, the more citric acid a fruit has the less likely bacteria can infect the fruit.

This relates to AP Bio through the involvement of genes in protein synthesis. During protein synthesis in a cell, the first thing that happens is transcription where information on the DNA is transcribed onto mRNA. The mRNA then is sent to the Rough Endoplasmic Reticulum where it is received on the cis face. There, on the ribosomes of the rough ER, the protein is synthesized. The type of protein that is synthesized here is determined by the information of the mRNA. Then the protein is sent to the Golgi where, based on the information from the mRNA, molecules are added to determine the final location of the protein. Genes, including PH4, are sections of DNA. Therefore, the PH4 gene, in part, determines what type of proteins are produced by the cell and where they go.

Wow! It is fascinating how a gene can influence an orange’s taste. I found this research so interesting because I love oranges. I wonder how other plants’ genes influence their taste?

To Smell or Not to Smell?: The Dangers of Covid-19 on your Senses

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On December 31, 2020

In Student Post

Out of all the symptoms caused by Covid-19, one of the most bizarre was the complete loss of taste and smell. The loss of taste and smell, more formally known as anosmia and ageusia, is now a very common symptom of Covid-19. Over 80% of people who catch the virus experience it, and it has become one of the most effective ways to diagnose the virus. However, the loss of taste and smell is different for Covid-19 than a regular cold or flu. For Covid-19 loss of taste and smell occurs regardless of a stuffy nose and it can last from 8 days to a whole month. In worse case scenarios those senses don’t come back at all.  Although this is a widely known symptom of Covid-19, have you stopped and wondered why this occurs? 

At first there was a lot of confusion as to why the virus affected our taste and smell. Some scientists thought signs of anosmia meant Covid-19 had entered the brain through the nose. This then damages the olfactory sensory neurons (sensory neurons in the nose) causing lasting damage to the brain. However, with more research and data this fortunately doesn’t seem to be the case. Experts at the Harvard Medical School have been conducting research on this topic and have come up with a possible reason why people have been experiencing anosmia.  To understand how the virus affects people, you first need to know how the virus enters the body. The virus enters the body through a process called receptor-mediated endocytosis. The virus enters the body through the nose and mouth then binds to a certain receptor called the ACE2 receptor protein found in many parts of the body, such as the lungs, liver and kidney. After binding to the receptor the virus enters the cell and releases its own genetic material that gets copied to produce more of it as well as more viruses to spread to the whole body. The researchers at the Harvard Medical School have found that olfactory sensory neurons don’t contain the ACE2 receptor protein, so there isn’t a way that the virus could enter through those cells. Instead they believe the virus affects nonneuronal cells that support the olfactory sensory neurons, such as basal cells and sustentacular cells found in the olfactory epithelium. The virus affecting these cells is what might be causing the loss of smell due to the sensory neurons not being able to function properly without it’s normal support.  There is a lot less known about why the loss there is a loss of taste as well, since taste receptor cells also don’t contain the ACE2 receptor protein. There is still a lot of speculation and a lot more research needed to be done.  However this is good progress and some insight as to how this virus is affecting the senses. 

As stated before most Covid-19 cases people get their sense of taste and smell back, but what happens if your fully recovered and your senses still haven’t returned? In one severe case a teen named Kenny Mayfield caught the virus and has yet to get his senses back. In March, when little was known about the virus, Kenny had been suffering through Covid-19, but wasn’t sure due to lack of testing and knowledge available during that time. After several months when he tested positive for antibodies he was certain that was the case. Although he was no longer suffering from the virus itself, he still had to face the consequences of it, his sense of smell had not returned. Now months later he is still trying to regain his sense of smell. He practices scent retraining to get back his senses, but the process could take 6 months to a year for it to get back to normal. He is able to taste, but without his scent it has become less enjoyable to him, causing him to lose his appetite and lose weight. There have been several other cases just like this one. A man named Eian Kantor has gone 7 month without his senses and is desperately trying to get them back to no avail. Another woman named Freya Sawbridge has begun to regain her sense of taste and smell, but claims everything is warped and unpleasant. Not only with food, these loss of senses can be incredibly dangerous if you can’t smell a gas leak or a fire.  Covid-19 can have a serious effect on your sense of taste and smell and should be taken much more seriously.

The most important thing you can take from this article is awareness. Although it is known that you lose your sense of taste and smell due to Covid- 19, I picked this specific topic because I’ve been very curious about why and how this occurs. I wanted to know more information on it.  Many people shrug off the symptom of loss and taste and smell, because they feel guaranteed that they will get it back. However, like these cases described, it is not always a definite guarantee things will go back to normal. You could end up never getting your senses back or have them return very altered. That is why it is essential to stay safe and keep yourself and others protected. Don’t take the risk, because you could be the one person to experience long term damage that could change your life forever. 

 

The Impact of Newfound Generalized Taste Buds in Mice

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On October 19, 2020

In Student Post

Background Information on Taste buds

According to this article about how taste buds work, taste buds are composed of cells that are structural, and cells that are chemical receptors. The surfaces of the receptor cells have proteins that bind with the chemicals that cause our perception of taste. As you all (should) know, the tongue does not actually have different sections for each flavor but instead, it has many different types of receptors that are stimulated by certain chemicals in food. The different reactions of receptors, which recognize bitter, sweet, sour, and umami flavors, are determined by specific genes in the DNA (It’s important to take note that the production of certain proteins and certain sequences of the DNA will even affect something as “simple” as taste). The receptor for salt, aka the epithelial sodium channel, functions differently from these receptors. It is basically a membrane that allows ions of sodium to permeate into specific cells.

 

The Mouse Research

An article (source article) from sciencenews.org reveals the findings of a research project that resulted in the discovery of generalized taste buds in mice that have the ability to taste four of the five flavors that these cells can recognize. These flavors include bitter, sweet, sour, and umami. The traditional belief in taste bud functionality is that taste buds only sense one or two specific flavors. Although mice possess both types of taste buds, the new research shows that clearly, the process is not as simple as just sensing specific tastes. Another article from sciencenews.org explains an experiment that demonstrates how taste is not just dependent on the taste buds themselves, but the brain plays a significant role in taste reception. In this experiment, certain receptors in the brains of mice were stimulated while the mice were drinking normal water. This caused the mice to react as if they were tasting sweet or bitter substances. The results of this experiment show that taste buds work with the brain to stimulate the perception of flavor.

Brown mouse eating

This mouse is currently eating, meaning that its taste buds are currently sending signals to the brain to stimulate the perception of flavor.

Going back to the first article, mice need a specific protein that allows the generalized taste bud to send signals to the brain. Through research, it was discovered that the taste buds with broader ranges did not function in the absence of this specific protein. This goes to show the many functions and the vast significance of proteins in organisms. Additionally, some of the taste buds that only sense specific flavors were not functioning as well. Due to this, researchers believe that these two different types of taste buds depend upon each other to send signals to the brain.

 

So What?

At this point, you may be wondering why certain functions of the taste buds of mice matter. In case you didn’t know, the taste buds of mice function similarly to those of humans. This means that further research on the taste buds of mice may contribute to human interests as well. For example, one’s sense of taste can be lost through certain treatments (ex: chemotherapy) and aging. This may potentially lead to loss of appetite, causing malnourishment and other issues. With more research, these conditions could be treated through artificial taste bud receptors and even more by understanding the relationship between taste buds and the brain. Personally, I believe that this research is good support for those who are struggling with the loss of appetite, as well as a gateway to even more possibilities. I’d like to know more about your thoughts on this research. Is it worth the time and effort to learn more about this topic? Do you think that there are more possibilities than just treating loss of appetite? What else could this research be useful for?

A Gene In Your Ears For Sour Taste?

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On October 11, 2018

In Student Post

Unlike the other four human tastes, our process of detecting sourness has always been a mystery, and scientists were definitely not expecting to find the answer in a  protein normally found in the inner ear.

https://pxhere.com/en/photo/994259

This protein, coded by the gene scientists refer to as Otop1, usually functions as part of the vestibular system to maintain balance. Given this more commonly known function of the protein, scientists were shocked to find its use for both balance and detecting the acids often associated with sour taste. The association is actually not as far- fetched as one might think. Otop1 codes for the synthesis of calcium carbonate crystals which rest on the hairs of the inner ear and detect gravity to help humans stand upright. Researchers found that the tongue also uses these crystals to detect sour taste. Calcium carbonate, a relatively basic compound, dissolves when it comes into contact with acid, which reaction can be detected by the brain and interpreted as sour taste.

How could such a protein find its way to use in both our senses of balance and taste?

The answer lies in evolution. If a certain protein proves advantageous over generations, organisms with it in surplus may evolutionarily find other uses for the it. Recently scientists have actually found several proteins for sensory organs that double as homeostatic sensors in other tissues. Otop1 is only one of many; smell receptors are found in the kidney in surplus, as are sweet taste receptors in the bladder.

Although we have unearthed a lot about the human body over the years, there is always so much more to learn!

“What Does Light Taste Like?” I Don’t Know, Ask A Nematode.

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On November 28, 2016

In Student Post

csiro_scienceimage_2818_group_of_nematodes

by Entomology on scienceimage.csiro.au

The vision of light is a beautiful blessing brought to us by our sight receptor cells. Since the sight of light is so great, the taste of it must be even better. Though we don’t know the taste of light, there may be a very tiny someone who does, the nematode. In the article Tasting Light: New type of photoreceptor is 50 times more efficient than the human eye, published on sciencedaily.com, it states that, at the University of Michigan, researchers have discovered a new photoreceptor amidst a bunch of taste receptor cells in nematodes and other invertebrates. This new receptor is called, LITE-1. Because of the receptor’s unusual location, it is believed that these animals have an ability to taste light. New studies have also shown that LITE-1 is no average photoreceptor.

LITR-1 was discovered in nematodes, which are eyeless roundworms only measuring about a millimeter in length. You might be thinking, “Nematodes don’t have eyes. So why would they need photoreceptors?” Shawn Xu, a senior study author who has a lab at University of Michigan Life Sciences Institute, where he is also a faculty member, demonstrated in his lab that even though nematodes are  eyeless, they still move away from flashes of light. The purpose of photoreceptors is to transform light into a signal that is usable for the body. This fact leads scientists to believe that it’s possible for that the roundworm uses this photoreceptor, located among its taste receptors, so that it can convert light into something that the worm can taste in order to perceive it. Xu also says that “LITE-1 actually comes from a family of taste receptor proteins first discovered in insects.”

Though these nematodes are extremely tiny, their peculiar LITE-1 photoreceptors are nothing to be looked over. Something that makes LITE-1 strange is that it has the astounding ability to absorb UVA and UVB light. Another unusual trait of LITE-1 is that it is unlike other photoreceptor proteins. Photoreceptors consist of two parts: a base protein and a chromophore. Breaking these two sections apart does not destroy all of their ability to function. However, LITE-1, when broken apart loses its ability to absorb light entirely.

LITE-1 also has a range possible future uses, such as being applied as a sunscreen that can absorb harmful rays or being used to promote the development light sensitivity in new types of cells. The future of LITE-1 shows great promise  and could open doors for the potential of other animals, besides invertebrates, to have a new and possibly delicious way of sensing light.

 

http://www.cell.com/cell/abstract/S0092-8674(16)31518-5

http://www.natureworldnews.com/articles/32317/20161119/animals-taste-light-new-type-photoreceptor-found-invertebrates.htm

 

 

Is it Time for a New Hot Chocolate Mug?

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On January 10, 2013

In Student Post

Hot Chocolate in front of a fireplace on a cold winter’s day is one of life’s finest delights. And, according to research done at the Polytechnic University of Valencia and the University of Oxford, the flavor of your mom’s famous hot cocoa can be enhanced by the color of the mug you drink it out of. It has been found that drinking hot chocolate out of a cream or orange colored cup can improve the flavor. Researchers had fifty-seven people drink the same hot chocolate (unbeknownst to them) out of four differently colored cups: white, cream, red and orange with white on the inside. Most participants found that the beverage tasted best when had out of the orange and cream colored cups. This shows that the brain also takes into account visual stimuli, on top of flavor and aroma, when processing taste. Similar effects have been seen with other beverages as well. For instance, a yellow color improves the lemon flavor in certain soft drinks, a pink cup makes some drinks taste more sugary, and brown cups seem to give coffee move flavor. So, the next time you go to drink hot chocolate, make sure that you pick the cream or orange colored cup!

Sweet Genes Not So Sweet

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On March 20, 2012

In Student Post

Do you enjoy eating foods that taste sweet? Do you also like to eat meat? Well, what would you do if you ate so much meat that your genes responsible for detecting the sweet taste suddenly stopped? Would you be upset? I certainly would be. Thankfully, humans do not have to worry about this problem yet, but a recent study shows that animals that are specialized carnivores have lost the power to taste sweetness.

Credit: Martin Heigan

The study analyzed twelve different mammals and their sweet detector gene Tas1r2. The researchers found that in seven out of the twelve animals, Tas1r2 experienced mutations. The gene carried disabling glitches in hyenas, otters, fossa, banded linsang, sea lions and two different kinds of seals. What these animals have in common is that they are all predators. The study’s coauthor Gary Beauchamp believes that this means that the mutations in Tas1r2 “could easily spread through populations.”

While these carnivores have lost their ability to taste sweetness, this loss is not universal among meat eaters. For example, animals like red wolves are fervent meat eaters, but have not lost their genetic sweet spot. Beauchamp believes that the carnivores that have not lost the function of this gene will soon lose it in the future due to evolution.

However, there are many arguments in opposition to Beauchamp’s proposal. Animals that do not specialize in meat may have also lost their ability to taste sweetness. Chickens eat both plant and animal foods, but do not seem to notice sweetness in their food and appear to lack a functional Tas1r2. Huabin Zhao of Wuhuan University in China believes that chickens are just one reason that Beauchamp’s conclusion is not convincing. Zhao suggests that “narrow diet specialization might be a better explanation” for the meat-eater sweet-loss scenario.

The only way to determine if Beauchamp’s conclusion is valid is

to see if there will be disabling genetic glitches in Tas1r2 in other types of carnivores in the future. If this does occur, then this genetic mutation has the potential to shape the evolution of carnivores. Similar to these carnivores, people have also had their “use-it-or-lose-it” sensory evolution. For example, humans are not great at detecting odors and even worse when it comes to noticing pheromones, the strong animal-to-animal chemical communications. Only time will tell if the mutations of Tas1r2 will spread to all carnivores, but let’s hope humans do not lose the functionality of their sweet detector gene because sweet food tastes too good!

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