BioQuakes

AP Biology class blog for discussing current research in Biology

Tag: dna editing

Human Body Pig Kidney

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On April 17, 2024

In Student Post

For decades, scientists have been trying to figure out an alternative to conventional organ transplants due to the overwhelming need for human organs. With advancements in technology, a few experiments have been conducted with pig organs as an alternative, but mostly on brain-dead patients for safety. The exceptional pig-heart transplant on a living patient was unsuccessful, as the patient died shortly after the transplant. However, just recently, surgeons at Massachusetts General Hospital transplanted a pig kidney into a 62-year-old living patient, Richard Slayman. National Guard Kidney Transplant 099This surgery may be the first successful example of pig organ transplantation of many to come in the future, as he is expected to be discharged from the hospital soon. Slayman, who is recovering well after the kidney transplantation, sees his surgery not only as a way to help himself but also to provide hope for thousands of people in need of a transplant. Slayman has been on dialysis for the previous seven years after being diagnosed with type 2 diabetes and high blood pressure before a human kidney transplant in 2018, which showed signs of failure just five years later, restarting dialysis in 2023 and causing serious health problems. With the massive population in need of a human kidney, Slayman couldn’t have survived the wait time, according to his doctor Winfred Williams. The opportunity to receive a pig kidney became Slayman’s only hope as he later consented to the operation. Biotechnology company eGenesis uses the gene-editing system CRISPR to tweak the genes of pigs to make the pig organs suitable for people. With a total of 69 genetic edits in the pig’s DNA, the scientists took out sections of pig genes that the human immune system attacks and added seven human genes that help prevent immune-related problems possible of causing transplant rejection. In addition, they also disabled endogenous retroviruses in pigs’ genomes as they can hurt humans. This CRISPR technology has always been used in recent years to produce a solution to treat sickle cell disease, first approved in the U.K. and later in the U.S. in December 2023. CRISPR technologies have also been used to modify immune cells to attack tumors and cancerous cells in personalized cancer treatments. The apparent success of Slayman’s surgery represents not only a breakthrough in organ transplantation but also a potential solution to solving the unequal access for ethnic minorities to organ transplants and resources due to organ shortage and other problems. This connects to what we’ve learned in AP Biology on how different blood types can only receive blood donations of certain other blood types for their antigens exhibited. Carrying this to organ transplants means for some blood types, it’s extremely hard to find a matching organ for transplant. With this CRISPR pig kidney transplant marks a breakthrough in solving this problem. If you were to face an organ transplant, would you want to wait for years for a matching human organ or take the risk for a CRISPR pig organ?

 

Is De-Extinction Upon Us? The Woolly Mammoth is Planned to be Introduced Back on Earth by 2027

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On March 15, 2023

In Student Post

You may be familiar with the large Woolly Mammoth’s (Mammuthus primigenius) from the movie Ice Age. These animals had once roamed the Earth for thousands of years, only recently going extinct at the end of the Pleistocene Period. Scientists Ben Lamm and George Church are leading the research into the second ever human provoked de-extinction, planning to release the Mammoth’s in Siberia. With an initial $15 million dollars in private funding, the team has received an additional $60 million to help achieve the 2027 deadline.

The closest living relative to these Mammoths is the Asian Elephant. Having once shared an ancestor 6 million years ago, scientists are working on pinpointing the genetic differences that set the ancient species apart from their modern (living) cousins. Fragments of Mammoth DNA have been retrieved from their ancient fossils (One of my previous blogs I wrote about DNA in fossils!), making it possible for scientists to modify the genome of an elephant to produce something that would look and act like a mammoth. The team will try to create an elephant embryo with its genome modified to resemble an ancient mammoth. To do this, the scientists will need to remove DNA from an elephant egg and replace it with the mammoth-like DNA. Some traits the Mammoth’s will need is dense hair and thick fat to withstand the cold environment. Siegsdorfer Mammut

Some other challenges to this de-extinction process is the actual birth of a fetal Mammoth. Scientists have been able to create a sealed bag that can support a fetal lamb up to four weeks, but for the Mammoth to be successfully birthed, it will require an artificial uterus big enough to house a fetus for around two years, reaching a weight of 200 pounds (~22~ months). While this may seem like an impossible task to many, the researchers behind this operation have stated that they’re eager and confident that their expertise will prevail, showing the world that editing DNA can bring extinct species back to life.

This article connects to our most recent unit in AP Bio of genes, genetics, and DNA. As we know genes in DNA are what make each person different from the other. Physical traits are mostly represented through gene pools (genetics), such as the thicker fat needed for the mammoth to survive. DNA editing is a crucial step to bringing back this animal and the scientists are working carefully to create the closest representation of the extinct species. This goal cannot be succeeded without the things we learned in this unit!

The presence of Wooly Mammoths in todays world can help the Siberian tundra as it has been overruled by moss. The moss acts as an insulator for the permafrost soil from the cold temperatures, thus melting the permafrost and releasing harmful gasses such as methane and Co2 into the atmosphere. Mammoths are considered “ecosystem engineers” because they feed on the moss and provide a natural fertilizer with their waste. With the moss being broken up, it would allow the grasslands to come back which keep the soil from eroding and melting. Ecologists have imported bison into the tundra in an attempt to help the tundra return to grasslands, but they believe the Mammoth’s will be much more effective.

While the team is multiple steps away, facing many challenges not yet conquered, they are continuing to push on with their research, inching closer and closer to making this reality. If this mission is a success, it will open the door to numerous DNA editing opportunities, restoration of the Siberian Tundra, and will remain a great feat of human advancement.

Siberian tundra 05

Could Christmas Island rats make a comeback? Thanks to CRISPR gene editing, they might!

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On March 20, 2022

In Student Post

From climate change to overhunting by humans, there are many factors which contribute to the extinction of species in the animal kingdom. The Christmas Island rat, also known as Maclear’s rat, went extinct a century ago in what is believed to be the first and only case of extinction of a species due to disease. It has always been believed that once a species goes extinct, it is gone for good. That is until recently when scientists began experimenting with “de-extinction” efforts to bring back the Christmas Island rat.

Little does this rat know that his family reunions may be getting a whole lot bigger!

As published March 9 in the science journal, Current Biology, a team of paleo geneticists from the University of Copenhagen recently conducted a study into gene sequencing the Christmas Island rat, in order to estimate the possibilities of future gene editing experiments which could bring the species “back to life”. The process of genetic editing for de-extinction efforts, as explained by the research team in their abstract, consists of first identifying the genome of the species and then editing the genes of similar species to make it more similar to that of that extinct one. The team used frozen somatic cells of the extinct rats, cells with a 2n number of chromosomes which are made during the process of mitosis. The team was able to sequence the rats’ genome, aside from some small portions which remain missing. They then had to identify the modern species which they could gene edit. Their findings established that the Christmas Island rat shares around 95% of DNA with the modern Norway brown rat. At this point, it

Now that the rat’s genome has been sequenced to the best of the team’s ability and a similar species has been identified, the gene editing possibilities are endless, especially with CRISPR technologies and techniques. “CRISPR” stands for Clustered Regularly Interspaced Short Palindromic Repeats in DNA sequencing. This system was discovered by a group of scientists, led by Dr. Emmanuelle Charpentier. CRISPR uses Cas9, an enzyme which cuts DNA at specified sections as guided by RNA. There are three different types of edits drone with CRISPR technology: disruption, deletion, or correction/insertion. Disruption editing is when the DNA is cut at one point and base pairs are either added or removed to inactivate a gene. Deletion editing is when the DNA is cut at two points and a larger sequence of pairs is removed. Correction/insertion editing is when a new gene is added into a sequence using homology directed repair.

Thomas Gilbert, the lead scientist on the team, says that he would like to conduct CRISPR gene editing experiments on living species of rats before attempting to replicate the DNA of an extinct species. For example, attempting to mutate the DNA of the Norway brown rat into that of the common black rat. Once this experiment is conducted, the possibilities of reviving the Christmas Island rat will be more clear. Until then, we can only hope! Do you think it’s possible to see the Christmas Island rat revived anytime soon?

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