Regeneration and dedifferentiation in marine worms

     A common belief is that if you cut a worm in half, you end up with two worms. Of course this is false but not entirely. In most cases, worm can regenerate lost body parts so only one half of the worm survive.

    A study led by Florian Raible at the University of Vienna set out to understand just exactly how worms can regenerate lost body parts and to what extent. The worm they chose to experiment on was Platynereis dumerilii, a type of marine worm. The reason this worm was chosen was because most worms rely on what is called a growth zone in order to regenerate. This growth zone usually houses stem cells which are used to repair the damage caused. However, marine worms, such as Platynereis dumerilii, can regenerate without a growth zone filled with stem cells. The researchers found that Platynereis dumerilii cells went under a process called dedifferentiation in order to regenerate. Cell differentiation is what causes the different types of individual cells found in multicellular organisms that require different cells for different functions. Dedifferentiation essentially undoes cell differentiation and returns the cell to a stem cell. This allows for Platynereis dumerilii to begin regenerating its lost body parts despite the lack of a growth zone. The dedifferentiated cells then went through differentiation again, returning to their original state before dedifferentiation

    The research also revealed that Myc and Sox2, components for stem cell producing medicine, played a role in the dedifferentiation of cells. Additionally, through a process known as single-cell transcriptomics, it was found that the stem cells responsible for Platynereis dumerilii's regeneration were split into two different camps, one that formed lost tissue and neurons and another camp that formed muscles and connective tissue.

Platynereis dumerilii

    I think this study was pretty interesting not for the fact that worms can regenerate but rather the fact that cells can revert back to a type of blank slate form. The article does state that "The concept of dedifferentiation was proposed over 60 years ago, but researchers at the time lacked the tools to test this idea" and that only now could they observe this process up close. In a previous post, I covered an article that used the term "reprogramming of cells" and it has once again appeared in this article, referring to dedifferentiation. It amazes me just how much we still have left to discover and how much a single piece of data could shake the world of genetics.

This gene may help worms live longer, but not healthier !

Links:
Article: http://www.punnettssquare.com
Related Article : https://www.sciencedaily.com/releases/2019/07/190717084249.htm


At the University of Pittsburgh, a geneticist studying aging named Arjumand Ghazi studies a gene that lengthens nematode worms' lives and allow how its necessity for reproduction also makes the worms more susceptible to infection and stress. Although usually longevity-promoting genes generally help organisms deal with stress, this proves to be the opposite in this case.

They found that a gene called TCER-1 increases life span and is needed for Caenorhabditis elegant worms to produce eggs and healthy offspring. However worms missing this particular gene fought off bacterial infection for nearly twice as long as worms with an intact gene, and worms that made more of the TCER-1 protein than usual succumbed to infection faster however they were able to overcome declines in fertility caused by exposure to a pathogen. These results indicated that when functioning normally, the gene helps suppress immune responses so more resources can be used for reproduction.

I found this article very interesting to read and understand how the body allocates resources, and how longevity genes in many animals increase resistance to stressors like infection. By diverted resources meant for stress management, the TCER-1 gene ensures that the animal reproduces efficiently to benefit the species.