BioQuakes

AP Biology class blog for discussing current research in Biology

Tag: light

Leading Science with Light

Emmett Chappelle was a African American Scientist and one who contributed greatly to Medicine, Philanthropy, and Astrochemistry. Chapelle was born on October 24, 1925 in Phoenix, Arizona where he grew up to attend Phoenix College. During his time at Phoenix college, he received an Associate’s Degree in electrical engineering and then a Bachelor’s of Science in biology at the University of California. Following, Emmett Chappelle taught biochemistry at Meharry Medical College. He received many offers for his graduate studies which he completed for his Master’s Degree at the University of Washington. Continuing his studies, Chappelle earned a Ph.D at Stanford University for 4 years before leaving for a research position at the Research Institute for Advanced Studies in Maryland. After years of hard work, he moved on to work at NASA before moving on to work at the Goddard Space Flight.

While at NASA, where Chappelle worked as a Exobiologist and Astrochemist, he made several discoveries. Perhaps the most important aspect of his work in the field of biology was his exploration of how light is given off by different organisms. Chappelle learned that certain chemicals give off light when mixed with living cells as long as adenosine triphosphate is present, and use this finding to detect bacteria in various samples, including bodily fluids, water, and other foods. Chappelle used this knowledge to develop a means to determine the health of plants. By measuring the amount of fluorescents emitted by plants in a forest, he was able to determine the amount of photosynthesis occurring within that forest. Chappelle’s study of the enzymes luciferin and luciferase, used by fireflies, to make their cells glow paved the path for many current scientists who still use these chemicals as florescent tags to see cancer cells.

Chappelle was inducted into the National Inventors Hall of Fame for his discoveries related to bioluminescence and the important roles they have played in many fields of science. Aside from his recognition for his scientific discoveries that earned him 14 US patents, Chappelle was also respected for his service in the United States Army and for the time he spent mentoring minority high school and college students. Although he passed away in October of 2019, Chappelle will long be remembered for his many contributions to science.

 

 

 

 

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

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

 

 

Sensing neuronal activity with light

neurons

Researches have recently developed a tool that may help in mapping the neural networks of living organisms using light. Observing these electrical signals of neurons can lead to numerous advancements in our understanding of neural circuitry.

In a collaborative study between Viviana Gradinaru, Frances Arnold and Barbara Dickinson, they developed a method to sense neuronal activity with light. These researchers used a protein named Archaerhodopsin (Arch) and exploited its light responsive qualities. They were able to optimize Arch through a process known as directed evolution. Using this method they created a variant of the Arch protein, called archer1 that acted as a voltage sensor under a red light and an inhibitor under a green light, while generating a light intensive enough to detect. When this protein acts as a voltage sensor it can show which neurons are active and synaptically connected and which aren’t under certain stimuli.

These researchers were able to test Archer1 in the worm C. elegans, which was chosen for its near transparent tissue that made it ideal for observing the luminescent protein. This was the first place they were able to observe the circuits of the neurons light up if they were expressed and dim down if they were repressed. For future studies they hope to make Archer1 bright enough to be detected through opaque tissue and accurate enough to detect voltage changed in more complex, behaving mammals. This study can prove to help us in our understanding of neural networks.

Original papers:

http://www.pnas.org/content/111/36/13034

http://www.nature.com/ncomms/2014/140915/ncomms5894/full/ncomms5894.html  (You can only read abstracts; you have to pay to read the full text)

Dr. Light

Cardiac arrhythmia is a problem with the rate of heart beat that currently affects 4 million Americans. During arrhythmia, the heart may beat too fast, too slow, or have an obvious irregular rhythm. In some cases, this heart condition may be life-threatening with the ability to damage the brain, heart, and other organs due to the lack of blood flow.

Oscar Abilez, a cardiovascular physician at Stanford University has developed the solution to this condition: light. With his team, he is working to create a new biological pacemaker that is able to control the heart with light. The first phase of his research involves optogenetics. This uses techniques from both optics and genetics to control the activity of individual neurons in living tissue. In 2002, German scientists were able to isolate the genes for the proteins called opsins. Before this discovery, algae and few other organisms were the only know carriers of light sensitive cells. These opsins, however, are responsible for cells’ light sensitivity in humans and modify the genetic code of other cells so that they, too, would produce these opsins. 

The next phase of his research involves stem cells. Oscar Abilez hopes to convert the stem cells light-sensitive cardiomyocytes from a person who is suffering from this condition.  These cells that make up the muscle tissue in the heart  would be able to be “grafted” onto a person’s heart. This would then ideally carry out Abilez’s vision, which he hopes will be achieved in the next decade or so, allowing physicians to control the whole heart’s rhythm using light.VPC_1

Jet Lag Prevention

Jet lag can be a difficult issue to deal with when traveling across time zones and no one wants to be drowsy while on their vacation. Jet Lag is caused when your circadian rhythm  is out of sync with the environment you are in. Circadian rhythm is the internal, biological clock that drive changes within most organisms. Normally, your circadian rhythm is controlled by several factors such as exercise and melatonin levels but the most prevalent factor is light exposure. Light exposure can cause phase shifts which are changes in your circadian rhythm. With this information, scientist have shown in a recent study that you can follow four simple steps to minimize jet lag:

1. Estimate when your body temperature reaches a minimum. If sleeping 7 or fewer hours per night, assume this is 2 hours before your usual wake time. If sleeping more, assume this is 3 hours before your usual wake time.

2. Determine whether you need to advance or delay your circadian rhythms. If you are flying east (to a later time zone), such as from Los Angeles to New York, you will need to phase advance. Otherwise, if you are flying west, you will need to phase delay.

3. If you need to phase advance, avoid light for 4 hours before your body temperature minimum, and seek light for 4 hours after it. Otherwise, do the opposite.

4. Shift your estimated body temperature minimum by one hour earlier per day if phase advancing, or one and a half hours later per day if phase delaying.

Photo taken by Mary Lane

 

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