Witnessing gene-cutting in action

The following article uses information from a variety of sources. The works referenced are listed at the end.

It’s described as debilitating. Each gasp for air can bring on a coughing fit, wheezing, or severe abdominal pain. Life with cystic fibrosis can be limiting, although more and more treatments are available to bring hope to those with the condition.

But the development of a new gene-splicing tool, the CRISPR, is rewriting science to address the underlying causes of diseases like cystic fibrosis. It all boils down to the human genome, with each DNA or RNA molecule playing an essential role in carrying out the proper function of the human body. On Jan. 14, scientists were able to capture the CRISPR in action for the first time since its creation. This provides greater insight into the understanding of the inner workings of gene-cutting, and also raises an important question: how important is it to visualize science, and what implications does this have for biology students?

Cutting it down

Freshman biology classes at MVHS spend a unit on genetic engineering that emphasizes the significance of the different structures of DNA. The life changing possibilities that exist within manipulating genetic material is an underlying theme throughout each lecture or lab and the CRISPR which is able to rewrite genes through the Cas 9, an enzyme with the ability to break bonds between the bases of DNA, reinforces this idea. However, the true origins of the tool may take many by surprise.

CAS9-Genome-Editing
This diagram shows how CRISPR can be used to edit genomes. The Cas9 protein can separate the two strands of DNA, and the guide RNA is used as a template for the genomic DNA. Image from origene.com

 

It all starts with a virus.

According to Ekaterina Pak, a biology student at Harvard Medical School, a virus is introduced to a bacteria cell, which produces a new region in the bacteria’s genome to defend against foreign objects. That new region is then integrated into the CRISPR’s RNA, which can be used for multiple different laboratory needs. In regards to genetic conditions, the CRISPR can essentially “cut out” errors in a gene.

Although this process seems groundbreaking, scientists have encountered a few restrictions. For one, it was physically impossible to monitor the CRISPR in action, leading to uncertainty and inconsistency in results. In addition, the Cas9 protein may cause additional mutations if it doesn’t align precisely with the desired section of DNA.

But scientists were able to move a step forward from those limitations, as a study led by Jennifer Doudna, a professor of molecular biology at UC Berkeley, developed a method for seeing the CRISPR in action.

By shooting X-rays through a crystallized form of the protein, the exact moment before the gene-splicing began was captured. The production of this image will allow further study in the accuracy of the CRISPR, and how it can be continually improved and revised to eventually be commonly available to fix certain genetic mutations.

Applications to medical biology

Current treatments for cystic fibrosis take the form of chest physical therapy, antibiotics, inhalers, or even lung transplants. Although these treatments are able to control symptoms and manage lung infections, it can be inconvenient and painful for patients to undergo this medical care.

But scientists see hope, as a study published in 2013 demonstrates the successful correction of the mutated gene in intestinal cells from pediatric donor patients. However, many are reluctant to test this process on a larger scale, as the effects of a few cells on a petri dish may not be repeated on an entire human body. The debate on testing new genetic tools on human embryos is ongoing and has escalated after a failed attempt on a human embryo in China.

Scientists hope to see further advancements in the near future, as the CRISPR is continually refined and perfected, that will allow the universal usage for cystic fibrosis and other related mutations.

In the classroom

Influential.

This is the first word that came to sophomore Carolyn Duan’s mind when she learned about gene-splicing in her freshman biology class. Although she hasn’t experienced the life-changing benefits firsthand, she believes that the ability to rewrite the genes of conditions like cystic fibrosis and sickle cell anemia is extremely beneficial.

“CRISPR is such a big deal since it allows scientists to splice genes a lot more accurately,” Duan said. “Scientists could base future machine designs off of this one, since it worked well.”

Duan also sees the implications of seeing CRISPR in action has for her AP Chemistry class. A lot of the time, labs are done to help students better visualize certain subjects or aspects of science, but Duan feels that it’s hard to draw parallels between the two.

“The idea of visualizing science should be implemented more in classrooms,” Duan said. “But I think the connection between the formulas and concepts should be emphasized more.”

As for AP Biology teacher Renee Fallon, the discovery of CRISPR in general reminds her of why she loves teaching biology in the first place. Its application to classrooms is a future pursuit, due to the many unknown facets that are still being tested.

“There are so many new biological discoveries that influence curriculum,” Fallon said. “A lot of the labs that we do in AP Bio I didn’t do until college.”

Genetic engineering is still included in current curriculum with a lecture and lab involving a green fluorescent protein and bacteria. Examples like sickle cell anemia are looked at to help students better understand mutations, and how future tools in the field of genetic engineering could be the solution to the problem.

According to Fallon, the accuracy of the CRISPR isn’t quite high enough to allow for modification of human genes, but it definitely holds a lot of potential, as many scientists and professors have asserted.

“It has got a huge impact on the scientific community,” Fallon said. “It’s likely to have a bigger impact than people realize. It’s still too new at this point, but it’s a potentially revolutionary technology.”


 

References

http://www.wired.com/2016/01/crispr-modification/http://sitn.hms.harvard.edu/flash/2014/crispr-a-game-changing-genetic-engineering-technique/

http://science.sciencemag.org/content/early/2016/01/13/science.aad8282

http://www.nytimes.com/2015/04/24/health/chinese-scientists-edit-genes-of-human-embryos-raising-concerns.html?smid=fb-nytimes&smtyp=cur&bicmp=AD&bicmlukp=WT.mc_id&bicmst=1409232722000&bicmet=1419773522000&_r=0

http://www.cell.com/cell-stem-cell/abstract/S1934-5909(13)00493-1

https://www.nhlbi.nih.gov/health/health-topics/topics/cf/treatment