Categories
Biomedical Research

A Brief Overview of Telomeres

By Saharsh Satheesh

Published 1:07 PM EST, Mon May 3, 2021

Introduction

For centuries, scientists have pondered about the human body and the structures that make us who we are. In recent decades, advances in genetics have helped us understand more about the human genome and the processes by which we are able to live. One notable advancement was in the study of telomeres. It had been known that telomeres, which are caps on the end of chromosomes, help protect the chromosome. However, its composition and true use was not well understood.

Cells constantly divide, and every time they divide, the DNA copies as well. When this occurs, the telomeres at the ends wear down. In humans, telomeres consist of a repeating sequence of 5’-TTAGGG-3’. This sequence can be repeated over 3,000 times and some cells can reverse the process of losing telomeres by using the enzyme telomerase, where it functions by adding telomeres. Telomerase is usually inactive in somatic cells but can be active in fetal tissue and germ cells.

Studies

As cells replicate, these telomeres shorten, and studies have shown that this is associated with aging. A paper by Masood A. Shammas explains that “Telomere length in humans seems to decrease at a rate of 24.8–27.7 base pairs per year [12,13]. Telomere length, shorter than the average telomere length for a specific age group, has been associated with increased incidence of age-related diseases and/or decreased lifespan in humans [10,14,15]. Telomere length is affected by a combination of factors including donor age [16], genetic, epigenetic make-up and environment [17–20], social and economic status [21,22], exercise [21], body weight [12,23], and smoking [12,24]. Gender does not seem to have any significant effect on the rate of telomere loss [13]. When telomere length reaches below a critical limit, the cells undergo senescence and/or apoptosis [25,26].”

Thus, according to Shammas, although “telomere length shortens with age, [the] rate of telomere shortening can be either increased or decreased by specific lifestyle factors. Better choice of diet and activities has great potential to reduce the rate of telomere shortening or at least prevent excessive telomere attrition, leading to delayed onset of age-associated diseases and increased lifespan.”

Future Prospects

Much is still to be understood about telomeres and the secrets that they hold. Scientists are currently studying how telomeres may be useful in better understanding and possibly preventing cancer. Cancer cells are able to use telomerase to continuously replicate, but, according to Jerry W. Shay, “inhibition of telomerase may thus represent a novel anticancer therapeutic approach. If we can suppress telomerase, we may be able to drive cancer cells into a growth arrest state. Many laboratories, including [his] own, are studying this at the present time, and the preliminary results are very encouraging.”

Saharsh Satheesh, Youth Medical Journal 2021

References

Shay, Jerry W. “Do the Telomeres in Cancer Cells Shrink?” Scientific American, Scientific American, 8 Jan. 2001, http://www.scientificamerican.com/article/do-the-telomeres-in-cance/.

Shammas, Masood A. “Telomeres, lifestyle, cancer, and aging.” Current opinion in clinical nutrition and metabolic care vol. 14,1 (2011): 28-34. doi:10.1097/MCO.0b013e32834121b1

“Telomere.” Wikipedia, Wikimedia Foundation, 2 Apr. 2021, en.wikipedia.org/wiki/Telomere.

“Telomeres and Telomerase (Article).” Khan Academy, Khan Academy, http://www.khanacademy.org/science/biology/dna-as-the-genetic-material/dna-replication/a/telomeres-telomerase.

“What Is a Telomere?” Facts, The Public Engagement Team at the Wellcome Genome Campus, 25 Jan. 2016, http://www.yourgenome.org/facts/what-is-a-telomere.

Categories
Health and Disease

Prions and Associated Diseases

By Saharsh Satheesh

Published 5:50 PM EST, Sun March 14, 2021

Introduction

In the last thirty years, a significant finding in the world of medicine was the discovery of prions. Essentially, prions are misfolded proteins that can cause neurodegenerative diseases. One of the earliest cases of a prion-caused disease was scrapie, a disease afflicting sheep. The disease may take several years to develop, but once its symptoms are noticeable, a sheep usually has less than six months to live. In the months following the first symptoms, such as nervousness and behavioral changes, the sheep may begin to lose weight and become unable to maintain muscle coordination.

The main method by which animals are infected with prions is ingestion; prions can be found in urine, saliva, and dead animals. These prions can also be transferred if one comes in contact with infected nervous tissue. For instance, ingesting infected meat may cause the formation of prions. Additionally, a mistake in translation of mRNA to a protein may cause a prion to develop.

Mad Cow Disease

Another disease caused by prions is BSE (bovine spongiform encephalopathy), more commonly known as Mad Cow Disease. The disease was first discovered in the 1970s, and current research hypothesizes that prions are the cause of the disease. The disease affects the nervous system, and one of its first symptoms is the inability to coordinate movements. Similar to scrapie in sheep, cows usually have less than six months to live after the first symptoms are noticed.

How does the disease spread in cows? The disease is spread when a cow is fed the flesh of farm animals that have bovine origin proteins in it. In order to prevent the spread, the solution was to implement a ban against feed that contains mammalian-origin proteins.

However, according to the FDA rules and regulations, “while the prevalence of BSE in the United States is very much lower than in European countries with BSE, evidence from the European experience has demonstrated that, in countries with a high level of circulating BSE infectivity, measures on only ruminant feed were not sufficient to eliminate all transmission of BSE; new cases continued to be found in cattle born in the United Kingdom after implementation of a ruminant-to-ruminant feed ban.”

Creutzfeldt-Jakob disease

An example of a prion-caused disease in humans is known as Creutzfeldt-Jakob disease (CJD). Both Mad Cow Disease and CJD are transmissible spongiform encephalopathies (TSEs), but CJD is only present in humans. Early symptoms of CJD include memory loss and reduced coordination, but as the disease progresses, those affected may mentally decline and go into a coma.

There are three common forms of CJD: sporadic, familial, and acquired. Sporadic CJD (sCJD) is the most common form, and it generally occurs in those over the age of fifty. This form of CJD is when a protein randomly misfolds. Familial CJD is far less common than sCJD, and this form is caused by inherited CJD. This form of CJD is noticeable at a younger age than sCJD. Lastly, acquired CJD is the rarest form, and it usually occurs when one comes in contact with infected tissue.

Saharsh Satheesh, Youth Medical Journal 2021

References

“About BSE BSE (Bovine Spongiform Encephalopathy).” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 9 Oct. 2018, www.cdc.gov/prions/bse/about.html.

“CREUTZFELDT – JAKOB DISEASE (CJD) AND MAD COW DISEASE.” 2011. PDF file. https://dhss.delaware.gov/dph/files/cjdmadcowfaq.pdf

Federal Register, Volume 73 Issue 81 (Friday, April 25, 2008), http://www.govinfo.gov/content/pkg/FR-2008-04-25/html/08-1180.htm.

“Prion Diseases.” Johns Hopkins Medicine, http://www.hopkinsmedicine.org/health/conditions-and-diseases/prion-diseases.

“Prion.” Wikipedia, Wikimedia Foundation, 17 Feb. 2021, en.wikipedia.org/wiki/Prion#:~:text=It%20has%20been%20recognized%20that,make%20it%20rearrange%20its%20structure.

“Prion.” Wikipedia, Wikimedia Foundation, 17 Feb. 2021, en.wikipedia.org/wiki/Prion.

“Scrapie.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., http://www.britannica.com/science/scrapie.

What Are Prions?, http://www.prionalliance.org/2013/11/26/what-are-prions/.

“What Is Scrapie?” Scrapie Canada, scrapiecanada.ca/about-scrapie/.

Yan, Yu, and Yu Yan. Fact Checking Project on the Film Fresh, 2 Sept. 2014, blogs.commons.georgetown.edu/cctp-638-yy326/claims-and-facts/are-cows-eating-dead-cows-as-feed/#:~:text=Bovine%20Spongiform%20Encephalopathy%20(BSE)%2C,animals%20that%20are%20probably%20infected.&text=As%20a%20result%2C%20cows%20might,eating%20dead%20cows%2C%20just%20indirectly.

Categories
Biomedical Research

Mitosis and the Cell Cycle

By Saharsh Satheesh

Published 5:40 PM EST, Mon February 8, 2021

Introduction

The cell cycle is a process most cells go through that ultimately results in a cell dividing into two daughter cells. Although it may sound like a relatively simple process, every step of the process is very complex.

The cell cycle is divided into two main sections: interphase and mitosis. Interphase is when a cell grows and replicates its DNA, while mitosis is when a cell splits into two identical copies of itself. So why do cells need to split into two? One reason is because if our cells are damaged, mitosis helps us create new cells to take the place of damaged or lost cells.

The cell spends the majority of its time in interphase, preparing to undergo mitosis. Furthermore, mitosis is the shortest phase of the cell cycle.  

Interphase

Interphase is made up of 3 separate phases: G1, S, and G2. During G1, the cell grows and acquires essentials for the upcoming DNA replication and mitosis. In the S phase, the DNA of the cell undergoes replication and the organelles and centrosomes start to duplicate. Organelles are membrane-bound structures in a cell. Centrosomes are organelles that produce spindle fibers during cell division. DNA replication is a complex process, but to put it in simple terms, the DNA replicates so that the two cells produced from mitosis have the same DNA. Finally, in the G2 phase, there is more growth, and the duplication of the organelles and centrosome complete. Upon completing these 3 sections of interphase, the cell may now undergo mitosis. 

Mitosis

Mitosis is made up of 5 distinguished sections: Prophase, prometaphase, metaphase, anaphase, and telophase, though some coin prometaphase and metaphase as simply metaphase. In prophase, the nucleus of the cell dissolves, and the DNA takes shape from chromatin, which is unraveled DNA, to chromosomes, which is tightly packed DNA. In addition, the centrosomes begin to move apart. In prometaphase, the nuclear lamina dissolves and spindle fibers begin to form. Kinetochores, which are protein structures that the spindle fibers attach to, form in the chromosomes. In metaphase, the spindle fibers complete attaching to the kinetochores, and as a result, the centrosomes get pushed even further to opposite ends of the cell, causing the chromosomes to line up in the middle. In anaphase, the tugging force from the centrosomes drifting apart pushes the chromosomes apart and they split down the middle. In telophase, the centrosomes get pushed apart so much that there are essentially two cells that are attached together by the middle. The nuclear lamina and nucleus reform, and chromosomes change back into chromatin. Finally, in cytokinesis, the cleavage furrow is split by the contractile ring which is made of actin filaments. The cell is pinched into two. At last, the cell has divided, and now the whole process may repeat.

Saharsh Satheesh, Youth Medical Journal 2021

References

“Cell Cycle.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., http://www.britannica.com/science/cell-cycle.

“Cell Cycle.” Genome.gov, http://www.genome.gov/genetics-glossary/Cell-Cycle.

“How Cells Divide.” PBS, Public Broadcasting Service, http://www.pbs.org/wgbh/nova/body/how-cells-divide.html.

“Https://Www.ncbi.nlm.nih.gov/Books/NBK9876/.” The Cell Cycle & Mitosis Tutorial, http://www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/cells3.html.

“Phases of Mitosis | Mitosis | Biology (Article).” Khan Academy, Khan Academy, http://www.khanacademy.org/science/ap-biology/cell-communication-and-cell-cycle/cell-cycle/a/phases-of-mitosis.

Urry, Lisa A., et al. Campbell Biology, 11th Ed. Pearson, 2017.

Categories
Biomedical Research

A Glimpse Into The Origin and Discovery of Viruses

Introduction

Viruses are microscopic organisms, smaller than bacteria, that are only capable of reproducing in a host. They are extremely small, most ranging from 20 to 400 nanometers. They are of particular interest to scientists because some of their characteristics resemble those of living organisms. For instance, they all contain a nucleic acid genome and a protein capsid. However, they are unable to reproduce without the help of a host.

A general misconception is that viruses and bacteria are the same. However, they are incredibly different. One notable difference between the two is their sizes. Bacteria, on average, are hundreds of times smaller than viruses, which rely on hosts to reproduce. Bacteria, on the other hand, are able to reproduce without a host, truly making them living organisms.

With viruses being so different, the question arises: how did they come to be in the first place? Did they evolve from another organism? Unfortunately, there is not a confirmed theory, currently, but scientists are running various experiments to try to uncover this mystery. The three main hypotheses that virologists have developed over the years include the regressive, progressive, and virus-first hypotheses.

The regressive hypothesis essentially claims that viruses were once cells that eventually became what they are today, having just a genome and protein capsid. The basis of this theory comes from the fact that some viruses have double-stranded DNA, similar to humans. The progressive hypothesis tackles the shortcoming of the regressive hypothesis: the inability to explain the origins of viruses with RNA. It essentially says that DNA and RNA acquire the ability to transfer from cell to cell. Lastly, the virus-first hypothesis — like its name implies — suggests that viruses must have evolved first, predating even cells. The support for this theory comes from the fact that viruses are simpler than cells and thus evolution may have caused more complex cells to form. However, viruses rely on hosts, so if viruses did evolve first, then it begs the question of how they managed to survive.

Tobacco Mosaic Virus

In the second half of the 19th century, a prevalent disease was causing the discoloration of tobacco leaves. Due to this discoloration, farmers faced huge losses as over half of their crops were gone to waste. To try to discover what was causing this, Adolf Mayer, in 1879, tried to spot the virus causing this. However, as technology for viewing viruses had not been developed at the time, Mayer was unable to identify the cause. In 1892, biologist Dmitry Ivanovsky discovered that whatever was causing this disease was able to pass through porcelain filters, which meant it was smaller than bacteria. Finally, in 1898, Martinus Beijerinck was able to prove the culprit causing the disease was in an entirely new family of its own, now known as a virus.

This discovery was the basis for understanding viruses and eventually led to Wendell M. Stanley winning the Nobel Prize in Chemistry (1946) for being able to “show that the tobacco mosaic virus is composed of protein and ribonucleic acid, or RNA.” Each discovery since the discovery of the tobacco mosaic virus has been crucial to understanding more about viruses and the natural world. In fact, Dr. Harvey J. Alter, Michael Houghton, and Charles M. Rice were awarded The Nobel Prize in Physiology or Medicine last year for discovering the hepatitis C virus.

Our understanding of viruses has come a long way since the discovery of the tobacco mosaic virus, but with improving technology and more research being conducted, there is no doubt our understanding of viruses will continue to expand in the years to come.

Saharsh Satheesh, Youth Medical Journal 2021

References

Elmer, Nicole L, and About the author Nicole L Elmer . “Where Do Viruses Come From?” Biodiversity Center, 8 May 2020, biodiversity.utexas.edu/news/entry/where-do-viruses-come-from.

H;, Lecoq. “[Discovery of the First Virus, the Tobacco Mosaic Virus: 1892 or 1898?].” Comptes Rendus De L’Academie Des Sciences. Serie III, Sciences De La Vie, U.S. National Library of Medicine, pubmed.ncbi.nlm.nih.gov/11570281/.

“Intro to Viruses (Article).” Khan Academy, Khan Academy, http://www.khanacademy.org/science/high-school-biology/hs-human-body-systems/hs-the-immune-system/a/intro-to-viruses.

Machemer, Theresa. “How a Few Sick Tobacco Plants Led Scientists to Unravel the Truth About Viruses.” Smithsonian.com, Smithsonian Institution, 24 Mar. 2020, http://www.smithsonianmag.com/science-nature/what-are-viruses-history-tobacco-mosaic-disease-180974480/.

Moorman, Gary W. “Tobacco Mosaic Virus (TMV).” Penn State Extension, 26 Dec. 2020, extension.psu.edu/tobacco-mosaic-virus-tmv.

“The Nobel Prize in Chemistry 1946.” NobelPrize.org, http://www.nobelprize.org/prizes/chemistry/1946/stanley/facts/.

“Nobel Prize in Chemistry.” Our Scientists, http://www.rockefeller.edu/our-scientists/wendell-m-stanley/2538-nobel-prize/.

The Origin of New Flu Strains, sphweb.bumc.bu.edu/otlt/MPH-Modules/PH/PH709_Influenza/PH709_Influenza4.html.

“The Protein Capsid.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., http://www.britannica.com/science/virus/The-protein-capsid.

“Three Hypotheses on Origin of Viruses.” Www.donga.com, 6 June 2015, 7:16, http://www.donga.com/en/article/all/20150606/410836/1/Three-hypotheses-on-origin-of-viruses.

“Tobacco Mosaic Virus.” Tobacco Mosaic Virus – an Overview | ScienceDirect Topics, http://www.sciencedirect.com/topics/medicine-and-dentistry/tobacco-mosaic-virus.

Vidyasagar, Aparna. “What Are Viruses?” LiveScience, Purch, 6 Jan. 2016, http://www.livescience.com/53272-what-is-a-virus.html.

Virus Structure. msu.edu/course/mmg/569/Virus%20Structure.htm#:~:text=All%20viruses%20contain%20the%20following,virus%20is%20called%20the%20virion.

“Viruses and Evolution.” History of Vaccines, http://www.historyofvaccines.org/content/articles/viruses-and-evolution.

“Viruses vs Bacteria.” The Bella Moss Foundation, http://www.thebellamossfoundation.com/pet-carers/treatment/viruses-vs-bacteria/.

Wessner, David R. The Origins of Viruses. Nature Publishing Group, 2010, http://www.nature.com/scitable/topicpage/the-origins-of-viruses-14398218/.

Wu, Katherine J., and Daniel Victor. “Nobel Prize in Medicine Awarded to Scientists Who Discovered Hepatitis C Virus.” The New York Times, The New York Times, 5 Oct. 2020, http://www.nytimes.com/2020/10/05/health/nobel-prize-medicine-hepatitis-c.html.

Categories
Biomedical Research

Possibility of Life on Venus – Phosphine and Microbial Life

Introduction

Since the dawn of history, mankind has been on the search for signs of life outside of Earth. Every quest past the boundaries of our knowledge, from studying microscopic organisms to the content of the moon, has been to quench our thirst for answers. Until recently, in the search for answers to life outside of Earth, Venus was largely overlooked, but a fascinating, recent finding could unleash and spark future studies on our neighboring planet.

Venus is our solar system’s hottest planet with average temperatures of 460 degrees Celsius (around 860 degrees Fahrenheit). Its atmosphere is composed primarily of carbon dioxide but also contains sulfuric acid. Venus’ atmosphere also is over 90 times denser than the Earth’s. This contributes to making Venus the hottest planet as the green-house effect is highly prevalent under these conditions.

With such stark differences between Earth and Venus, it is no wonder that scientists’ attention was turned to bodies that are more similar to Earth. However, recent detections of phosphine have ignited talk about the possibility of life on Venus.

Phosphine is a gas that on Earth is produced from biological processes such as bacteria in anaerobic environments or can be artificially manufactured. Structurally, it is three hydrogen atoms bonded to phosphorus. For scientists, it is the possibility of phosphine being emitted from biological processes that intrigues them since a biological process implies life. However, only twenty molecules of phosphine were found for every billion molecules, a relatively minute quantity. Nonetheless, there is phosphine, irrespective of the quantity, so perhaps mankind is a step closer to discovering extraterrestrial life. All of this boils down to one question: does the presence of phosphine indicate the presence of microbes and thus life on Venus?

Studies

Though phosphine may be produced from biological processes, some argue that the phosphine may have been produced in other ways. For example, Ngoc Truong and Jonathan I. Lunine authored a study in which “[they] hypothesize that trace amounts of phosphides formed in the mantle would be brought to the surface by volcanism, and then subsequently ejected into the atmosphere, where they could react with water or sulfuric acid to form phosphine.”

Others claim that phosphine may not be present on Venus’ surface altogether. A group of scientists challenged the finding of phosphine by re-analyzing ALMA data and finding the results “statistically unreliable.” In their paper, they explain how “ALMA observations presented by GRB20 provide several arguments to support the validity of their identification of the PH3 feature, including a comparison to the JCMT data and a test at offset frequencies. [Their] analysis, however, shows that at least a handful of spurious features can be obtained with [the other] method, and therefore conclude that the presented analysis does not provide a solid basis to infer the presence of PH3 in the Venus atmosphere.”

It is also important to note that Venus is not the first planet for phosphine to be found in; phosphine has been found in Jupiter, Saturn, and of course, Earth. What scientists are striving to understand, though, is whether the phosphine in Venus’ atmosphere is caused by geological, chemical, biological, or other processes. If phosphine was produced by the more exciting possibility, a biological process, it begs the question of how microbial life managed to arrive on Venus in the first place. One theory is that microbes appeared when Venus had oceans several hundred years ago, but after the oceans dried up, the microbes took refuge in the sky.

Conclusion

Although it may seem like these contradicting studies extinguish the chance of finding life on Venus, that is not the case. In researching and discovering anything, contradicting data and studies will be present, and even if the contradicting data proves to be correct, it is a healthy progression that advances our knowledge of science. For example, if future studies indeed establish phosphine is not a result of biological processes, then our understanding of science will improve. By the same token, if future studies prove the presence of phosphine in Venus’ atmosphere is a result of biological processes, our understanding of science will still improve.

Ultimately, though all of these findings are relatively new, one thing is certain: the search for life on Venus will develop and expand. NASA administrator Jim Bridenstine himself said it is “time to prioritize Venus.” Perhaps spacecraft in the near future may provide more information about the phosphine in the Venusian atmosphere. Until then, mankind will have to wait.

Saharsh Satheesh, Youth Medical Journal 2020

References

“All About Venus.” NASA, NASA, 2 June 2020, spaceplace.nasa.gov/all-about-venus/en/.

Gough, Evan. “Maybe Volcanoes Could Explain the Phosphine in Venus’ Atmosphere.” Universe Today, 30 Sept. 2020, www.universetoday.com/148094/maybe-volcanoes-could-explain-the-phosphine-in-venus-atmosphere/.

“NASA Mulls Venus Mission after Recent Discoveries.” Yahoo! News, Yahoo!, 17 Sept. 2020, news.yahoo.com/nasa-mulls-venus-mission-recent-201520659.html.

O’Neill, Mike. “Signs of Life on Venus? What This Means for Earthlings.” SciTechDaily, 31 Oct. 2020, scitechdaily.com/signs-of-life-on-venus-what-this-means-for-earthlings/.

O’Neill, Mike. “What Is Phosphine and Why Does It Point to Extra-Terrestrial Life Floating in the Clouds of Venus?” SciTechDaily, 22 Sept. 2020, scitechdaily.com/what-is-phosphine-and-why-does-it-point-to-extra-terrestrial-life-floating-in-the-clouds-of-venus/.

Patel, Neel V. “Not Finding Life on Venus Would Be Disappointing. But It’s Good Science at Work.” MIT Technology Review, MIT Technology Review, 30 Oct. 2020, www.technologyreview.com/2020/10/31/1011487/not-finding-life-on-venus-disappointing-good-science-phosphine-biosignature/.

Re-Analysis of the 267-GHz ALMA Observations of Venus. 21 Oct. 2020, arxiv.org/pdf/2010.09761.pdf.

Siegel, Ethan. “Don’t Bet On Aliens: Phosphine Is Amazing, But Doesn’t Mean ‘Life On Venus’.” Forbes, Forbes Magazine, 15 Sept. 2020, www.forbes.com/sites/startswithabang/2020/09/15/dont-bet-on-aliens-phosphine-is-amazing-but-doesnt-mean-life-on-venus/?sh=601f03674fbc.

Stirone, Shannon, et al. “Life on Venus? Astronomers See a Signal in Its Clouds.” The New York Times, The New York Times, 14 Sept. 2020, www.nytimes.com/2020/09/14/science/venus-life-clouds.html.