Megan Chu, Class of 2021
The fascination with as well as the search for immortality has been present in humanity for millennia. Recent scientific advancements in microbiology seem to be inching closer and closer to this elusive dream. Scientists are looking to plants and bacteria in our gut microbiome to unlock the secret of immortality. With this new knowledge, however, comes restraints since immortality is more complicated than just living forever.
Aging at the cellular level is primarily due to the shortening of the protective caps, telomeres, at the ends of the cell’s chromosomes. An inherent problem with replicating linear DNA is the loss of DNA at one end of the template strands of DNA. It would be very detrimental to the cell if important genetic information was lost because it was located at those susceptible areas of DNA. Instead, telomeres, which are unique repeating sequences of DNA, protect the ends of chromosomes during replication, ensuring that protein coding DNA is not lost. However, telomeres get shorter with each round of replication, which means that cells are limited to how many times they can divide. This inability to divide means that cells cannot “restore damaged tissues and/or replenish aging organs in our bodies” (Green, 2019). Furthermore, as a cell ages, its metabolic processes slow down, which is also associated with longer healing times, illness, and organ failure (Green, 2019).
One cellular mechanism that slows down this “molecular clock” of aging is the enzyme telomerase. Telomerase lengthens the telomeres at the ends of the chromosomes, which doesn’t completely immortalize the cells, but delays the aging process. It was first discovered in unicellular pond scum but has been found in multicellular organisms as well. However, these enzymes are highly divergent across eukaryotic species, so the recent discovery of its structure in plants could be the “key to understanding how this enzyme controls genome stability and cellular immortality in eukaryotic organisms” (LaMotte, 2019). On average, plants live much longer than animals so uncovering the role telomerases play in plants can hopefully be applied to human cells too.
In addition to looking to plants for clues to immortality, scientists are also researching how the gut microbiome can lengthen cellular life spans. The numerous species of microbes that coexist within animal guts have been connected to many aspects of health, including digestion, depression, and cancer. There have been studies that show that gut bacteria from healthy mice can restore the growth of muscle in mice that suffer from muscle atrophy. Building upon these studies, a team from the NTU Lee Kong Chian School of Medicine transplanted the bacteria from twenty four month old mice into six week old, germ free mice. After the transplantation, the young germ free mice exhibited more intestinal growth and neurogenesis, the production of neurons. After further testing, the scientists discovered that the transplanted bacteria from the old mice stimulated the production of a specific short chain fatty acid called butyrate. Butyrate then stimulates the production of hormones that help regulate the body’s energy and metabolism as well as reduce inflammation. Production of butyrate is one of the many cellular processes that slows down as we age, so the addition of bacteria that produce butyrate or butyrate alone “can compensate and support an aging body through positive stimulation” (Nanyang Technological University, 2019).
Although these findings are exciting, more research is needed to see if they apply to humans as well. Furthermore, restraint must be practiced with regard to whatever new technologies emerge from this research. For example, cancer cells utilize telomerases to achieve their uncontrolled growth. Therefore, drugs that lengthen the lifespans of all somatic cells could possibly increase rates of cancer. The quality of life, not just the quantity of life, must also be considered when weighing the possibilities of these new discoveries.
References
Aging at the cellular level is primarily due to the shortening of the protective caps, telomeres, at the ends of the cell’s chromosomes. An inherent problem with replicating linear DNA is the loss of DNA at one end of the template strands of DNA. It would be very detrimental to the cell if important genetic information was lost because it was located at those susceptible areas of DNA. Instead, telomeres, which are unique repeating sequences of DNA, protect the ends of chromosomes during replication, ensuring that protein coding DNA is not lost. However, telomeres get shorter with each round of replication, which means that cells are limited to how many times they can divide. This inability to divide means that cells cannot “restore damaged tissues and/or replenish aging organs in our bodies” (Green, 2019). Furthermore, as a cell ages, its metabolic processes slow down, which is also associated with longer healing times, illness, and organ failure (Green, 2019).
One cellular mechanism that slows down this “molecular clock” of aging is the enzyme telomerase. Telomerase lengthens the telomeres at the ends of the chromosomes, which doesn’t completely immortalize the cells, but delays the aging process. It was first discovered in unicellular pond scum but has been found in multicellular organisms as well. However, these enzymes are highly divergent across eukaryotic species, so the recent discovery of its structure in plants could be the “key to understanding how this enzyme controls genome stability and cellular immortality in eukaryotic organisms” (LaMotte, 2019). On average, plants live much longer than animals so uncovering the role telomerases play in plants can hopefully be applied to human cells too.
In addition to looking to plants for clues to immortality, scientists are also researching how the gut microbiome can lengthen cellular life spans. The numerous species of microbes that coexist within animal guts have been connected to many aspects of health, including digestion, depression, and cancer. There have been studies that show that gut bacteria from healthy mice can restore the growth of muscle in mice that suffer from muscle atrophy. Building upon these studies, a team from the NTU Lee Kong Chian School of Medicine transplanted the bacteria from twenty four month old mice into six week old, germ free mice. After the transplantation, the young germ free mice exhibited more intestinal growth and neurogenesis, the production of neurons. After further testing, the scientists discovered that the transplanted bacteria from the old mice stimulated the production of a specific short chain fatty acid called butyrate. Butyrate then stimulates the production of hormones that help regulate the body’s energy and metabolism as well as reduce inflammation. Production of butyrate is one of the many cellular processes that slows down as we age, so the addition of bacteria that produce butyrate or butyrate alone “can compensate and support an aging body through positive stimulation” (Nanyang Technological University, 2019).
Although these findings are exciting, more research is needed to see if they apply to humans as well. Furthermore, restraint must be practiced with regard to whatever new technologies emerge from this research. For example, cancer cells utilize telomerases to achieve their uncontrolled growth. Therefore, drugs that lengthen the lifespans of all somatic cells could possibly increase rates of cancer. The quality of life, not just the quantity of life, must also be considered when weighing the possibilities of these new discoveries.
References
- Green, Jenny. “Can plants tell us something about longevity?” 18 November 2019. [Internet] Available from: https://asunow.asu.edu/20191118-discoveries-asu-research-plants-longevity.
- LaMotte, Sandee. “Breakthrough discovery in plants’ DNA may lead to slowing aging process in humans.” 18 November 2019 [Internet] Available from: https://www.cnn.com/2019/11/18/health/plant-longevity-telomerase-scn-wellness/index.html?utm_source=CNN+Five+Things&utm_campaign=53ff160423-EMAIL_CAMPAIGN_2019_11_19_03_29&utm_medium=email&utm_term=0_6da287d761-53ff160423-96567457.
- Nanyang Technological University. “Bacteria in the gut may alter aging process, study finds.” 14 November 2019. [Internet] Available from: https://medicalxpress.com/news/2019-11-bacteria-gut-aging.html.
- Sandoiu, Ana. “Are gut bacteria the key to healthy aging?” 26 October 2018. [Internet] Available from: https://www.medicalnewstoday.com/articles/323484.php#1
