The Science of “Syzygy”: Genetic Engineering

“Just take a bite.”

She appraised him suspiciously, then dropped her jaw like a snake and bit into the pitaya’s flesh. “What is this?” she mumbled around ravenous bites.

“It’s called a pitaya. Tons of vitamin C and calcium. Our scientists blended in genes from a legume to—.”

A wet mouthful of pulp flew across the cell and slapped onto the wall.

“This is engineered?” Skye demanded.

“Yeah. So what?”

“Tampering with genes is wrong. That’s what created the Spores and cast humanity out into space. It’s not our place to overrule nature.” An angry flush tinted her face.

“It’s better than starving,” said Ash. “Genetic modification is the only way we can get plants to grow in these conditions.” 

– Syzygy Part I: Transient Phenomena

*

During my childhood in the 1990s, I subscribed to several kids’ science magazines. One issue—I believe it was National Geographic World, anyone else remember that?—featured a short story about the then-new practice of genetically engineering crops. In the story, a boy takes a class trip to a crop laboratory and pricks his finger on the “gene gun” used to introduce transgenes into plants. Superhero origin? Not exactly. The genes in question belonged to a potato, so the boy—given to sedentary television habits—begins taking root in the family sofa.

Twenty years later, our techniques for manipulating genes are far more sophisticated, and so have our fictions about genetic engineering. One of my favorites, Margaret Atwood’s Oryx and Crake, has proven eerily prescient (that’s Atwood for ya) in its depiction of human organs grown in pigs. Genetic engineering also plays a critical role in my own Syzygy novella hexalogy: after a genetic engineering catastrophe drives humans from Earth, survivors on a lunar colony must rely on those same techniques to cultivate food and curate their own limited gene pool. The incredible power of genetic engineering versus the deadly illusion that we can control nature constitutes a classic sci-fi duality. How do these respective forces operate? Let’s examine the science behind two key processes.

CONTROLLED GENOME EDITING: THE CRISPR-CAS9 SYSTEM

We’ve seen it in headlines, but what does it actually mean? Clustered regularly interspaced short palindromic repeats (CRISPR) are short, repetitive sequences of DNA. They form part of prokaryotic immune systems, helping organisms recognize and remove foreign genetic material introduced by viruses. In 2013, scientists harnessed this natural process as a gene editing tool. Modifying CRISPRs allows us to target specific sequences of DNA, such as errors in the genome that cause genetic disease. First, we create a piece of “guide RNA” to locate the piece of the genome we want to remove. When the sequence finds its match, an enzyme it produces called Cas9 binds to that piece of DNA and “cuts” it off (this is why the CRISPR-Cas9 system is often analogized as “molecular scissors”) and the cell repairs the damaged area. The same tool can be used to add or modify genes. While CRISPR-Cas9 is not explicitly named in Syzygy, I imagine the scientist characters using similar techniques and write to this capability.

mrs_41_11_832-842-November16.indd

Illustration of the CRISPR-Cas9 system. Image courtesy of Cambridge University Press (cambridge.org).

Although CRISPR-Cas9 techniques are still relatively new, they hold great promise for enhanced study of gene function. Medical advances, like new methods for curing genetic diseases, may follow. Critics, however, fear that such selective editing of the human genome will invite ethically debatable practices and new realms of social inequality. Both the research and the arguments rage on. Meanwhile, laboratories aren’t the only places where organisms can alter their DNA.

EVOLUTIONARY EXCHANGES: HORIZONTAL GENE TRANSFER

One of Syzygy’s critical plot concepts is lateral or horizontal gene transfer (HGT), a mechanism of gene acquisition which involves movement of genetic material between different species. For example, pathogenic fungi or bacteria can introduce new genes into the plants they infect. (This was an alternative method to the gene gun in the early days of genetically modified crops.) HGT appears to play an important role in evolution, particularly among prokaryotes.

We eukaryokes aren’t above stealing genes, either: a study published in 2017 found that hundreds of human genes probably came from non-mammalian sources, suggesting HGT may be more prevalent in our own species than previously thought. That’s right, in addition to whatever ethnic ancestry we claim, we’re also part bacterium, fungus, and alga. These “transgenes” acquired from other species can confer new abilities to their possessors. For example:

  • Sequencing of a certain soil-dwelling amoeba revealed 18 genes likely acquired through HGT from bacteria, which conferred new functions on the amoeba such as a new type of enzymatic activity.
  • Galdieria sulphuraria, a red alga that lives in extreme environments, probably acquired some protein-encoding genes that help its ecological adaptation through to HGT from bacteria.
  • Colletotrichum, a genus of plant-pathogenic fungi, developed niche adaptations from at least 11 independent HGT events from bacterial genomes.
  • HGT probably helped some types of nematodes (animal parasites) develop the ability to infest plants as well.

FACT, FICTION, AND “FRANKENFOODS”

Although our genetic modification capabilities have come a long way since the 1990s, public opinion remains conflicted. Catchphrases such as “frankenfoods” and “designer babies” function as miniature horror stories about the consequences of genetic meddling. While any new technology has good and bad aspects depending on application, genetic engineering presents a twist because it’s an inherently natural process. Unlike cars or computers, which require humans to design and construct them, genes can change independently in spite of (or in addition to) human intervention. How will the escalating interaction between humans and genetic science unfold? Science fiction like Syzygy will continue exploring this question.

Check out previous posts in the Science of Syzygy series for the real science behind space elevators, lunar colonization, and terraforming.

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