Exploring the Possibility of Resurrecting Extinct Species
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The Future of Gene-Editing
It may resemble a plot from a science fiction story, yet scientists are actively pursuing the revival of species that have vanished from our planet. They are also exploring methods to make foods like milk, eggs, and peanuts safer for individuals with allergies, in addition to addressing inherited conditions such as Cystic Fibrosis and Sickle Cell Anemia. But how is this all achievable?
The key lies in gene-editing, particularly through a groundbreaking technology known as CRISPR-Cas9. This acronym, which stands for Clustered Regularly Interspaced Short Palindromic Repeats and CRISPR-associated protein 9, has transformed the landscape of scientific advancements, enabling feats that were once deemed unattainable.
What are the mechanics behind this technology, what applications does it have, and how might it influence our future?
The Emergence of CRISPR-Cas9
In 2012, researchers Jennifer Doudna and Emmanuelle Charpentier introduced the most advanced gene-editing tool available today: CRISPR-Cas9. This innovation empowers scientists to alter the DNA of various organisms—be it animals, plants, or microorganisms—by adding, removing, or modifying DNA sequences. Their remarkable work earned them the Nobel Prize in Chemistry in 2020, marking a historic moment as they became the first women to receive this accolade, setting a precedent for future scientific endeavors.
Though CRISPR-Cas9 is a synthetic construct, it draws inspiration from a natural phenomenon. Bacteria, which can be attacked by viruses, have developed an adaptive immune mechanism called CRISPR. When a virus injects its DNA into a bacterial cell, the CRISPR system captures fragments of this DNA and incorporates them into its genome. These sites of integration are known as CRISPR.
A crucial component of this system is the Cas9 protein, which carries RNA and actively seeks its complementary DNA. Upon locating this DNA, the Cas9-RNA complex works together to cut and eliminate it.
The ability of the Cas9 protein to be programmed for specific DNA sequences is significant. When DNA strands are severed, cells instinctively attempt to repair them. Hence, if scientists intentionally create breaks in targeted DNA, cells will endeavor to mend them. Doudna and Charpentier realized that by leveraging the natural function of CRISPR, they could develop a gene-editing tool that allows manipulation of any organism's DNA.
For instance, CRISPR-Cas9 could potentially eradicate Cystic Fibrosis by inducing a break in the genetic mutation responsible for the disease, prompting cells to repair it. If the repair process results in a correct DNA sequence, the organism would effectively be cured.
Ethical Considerations of CRISPR-Cas9
Since its inception, CRISPR-Cas9 has facilitated remarkable advancements. Scientists have engineered crops that withstand mold, pests, and drought, while also creating miniature pigs. However, the widespread availability of CRISPR-Cas9—where a starter kit can be purchased online for as little as $65—has raised significant ethical questions regarding its application.
In 2018, biophysics researcher He Jiankui made headlines by announcing the birth of the first gene-edited babies, utilizing CRISPR-Cas9. Working with eight couples, one partner of which was HIV-positive, Jiankui manipulated embryos in a lab setting, hoping to create individuals less susceptible to HIV. His actions ignited global outrage, even though he anticipated acclaim for his work.
Editing embryonic DNA means that the modifications could be inherited by future generations, potentially leading to unforeseen consequences—both beneficial and detrimental. Jiankui was ultimately sentenced to three years in prison for "illegal medical practice," a decision aimed at deterring similar actions by other scientists.
Could de-extinction be a potential outcome of CRISPR-Cas9? Researchers are already making strides toward reviving species such as the passenger pigeon, with hatching anticipated in 2022. Additionally, a team from Harvard is diligently working on resurrecting the woolly mammoth, a creature that has not roamed the Earth for millennia.
The implications of altering the natural ecosystem for human benefit are profound. While CRISPR-Cas9 holds the promise of positive change, it also possesses the potential to lead to adverse outcomes. The question remains: how far will science proceed in this endeavor?
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