Nav: Home

First-ever spider glue genes sequenced, paving way to next biomaterials breakthrough

June 05, 2019

UMBC postdoctoral fellow Sarah Stellwagen and co-author Rebecca Renberg at the Army Research Lab have published the first-ever complete sequences of two genes that allow spiders to produce glue--a sticky, modified version of spider silk that keeps a spider's prey stuck in its web. The findings appeared in Genes, Genomes, Genetics.

The innovative method they employed could pave the way for others to sequence more silk and glue genes, which are challenging to sequence because of their length and repetitive structure. Better understanding of these genes could move scientists closer to the next big advance in biomaterials.

Sticky solutions

Spider silk is what spider webs are made of, and it's been touted for years as the next big thing in biomaterials because of its unusual tensile strength combined with its flexibility. There are more than 45,000 known species of spiders, each of which makes between one and seven types of silk. However, despite many partial sequences, less is known about the full genetic structure of spider silk: Only about 20 complete genes have been sequenced. "Twenty pales in comparison to what's out there," Stellwagen says.

Plus, spider silk has proven tough to produce in large amounts. Spiders convert liquid blobs of silk into solid, spindly fibers in a complex process inside their bodies. Scientists can make the liquid, but "we can't replicate the process of going from liquid to solid on a large industrial scale," Stellwagen says.

Spider glue, however, is a liquid both inside and outside the spider. While the glue "does have its own challenges," Stellwagen says, that difference might make spider glue easier to produce in a lab than silk.

Stellwagen sees great potential for spider glue applications as organic pest control. After all, she says, "This stuff evolved to capture insect prey."

For example, farmers could spray the glue along a barn wall to protect their livestock from insects that bite or cause disease, and then could rinse it off without worrying about polluting waterways with dangerous pesticides. They could use glue similarly to protect crops from pests. It could also be applied in areas where mosquito-borne illnesses are prevalent. "It could also just be fun to play with," Stellwagen says.

A "behemoth of a gene"

Before Stellwagen and Renberg's work, which was funded by the Army Research Lab, the longest silk gene sequenced was about 20,000 base pairs. When she started this project, Stellwagen was expecting to sequence the glue genes quickly and then move on, building on what she learned from the sequence. Instead, it took her and Renberg two years just to finalize the sequence.

"It ended up being this behemoth of a gene that's more than twice as large as the previous largest silk gene," Stellwagen says. It was a long, hard road to the day she found Renberg in the lab and said, "I think our gene is 42,000 bases long. I think we finished it." And in the end, it was taking a risk on a cutting-edge technique that finally yielded the complete sequence.

Not only was the gene exceptionally long, but, like spider silk genes, it has many repetitions of the same sequence of bases--A, T, G, and C--in the middle. Modern sequencing techniques (called "next generation sequencing") work by generating DNA sequences for all of an organism's genes, but chopped up in little pieces. Then, like solving a puzzle, scientists must match up the overlapping ends of the short sections to determine the entire sequence.

However, if your gene is repetitive, you need a single sequence, or "read," that extends from before the repetitious region to beyond the end to know how many repetitions there are. If your repetitious section is long, as it is in the glue genes Stellwagen and Renberg studied, the chance that you would get the read you need with next-generation methods is slim.

Fortunately, "third-generation" sequencing techniques are now available. Third-generation sequencing produces longer reads, but fewer of them. Only by repeating the experiment several times do you have a chance of getting the reads you need to determine the number of repetitions and finally define the gene's entire sequence. "It's challenging," says Stellwagen. "You're picking a needle from a haystack."

But it worked. After two years of going to the computer and not seeing positive results, Stellwagen and Renberg finally got the reads they needed to define the entire gene's sequence.

Stellwagen is already thinking ahead to what comes next. "Now that we have a protocol for discovering full-length silk genes, what do silks from other species look like?" she asks.

"I'm super excited that I was able to finally figure out the puzzle, because it was just so hard," Stellwagen says. While it was a much bigger challenge than she expected, "Ultimately we learned a lot, and I am happy to put that out there for the next person who is trying to solve some ridiculous gene."
-end-


University of Maryland Baltimore County

Related Genes Articles:

New alcohol genes uncovered
Do you have what is known as problematic alcohol use?
How status sticks to genes
Life at the bottom of the social ladder may have long-term health effects that even upward mobility can't undo, according to new research in monkeys.
Symphony of genes
One of the most exciting discoveries in genome research was that the last common ancestor of all multicellular animals already possessed an extremely complex genome.
New genes out of nothing
One key question in evolutionary biology is how novel genes arise and develop.
Good genes
A team of scientists from NAU, Arizona State University, the University of Groningen in the Netherlands, the Center for Coastal Studies in Massachusetts and nine other institutions worldwide to study potential cancer suppression mechanisms in cetaceans, the mammalian group that includes whales, dolphins and porpoises.
How lifestyle affects our genes
In the past decade, knowledge of how lifestyle affects our genes, a research field called epigenetics, has grown exponentially.
Genes that regulate how much we dream
Sleep is known to allow animals to re-energize themselves and consolidate memories.
The genes are not to blame
Individualized dietary recommendations based on genetic information are currently a popular trend.
Timing is everything, to our genes
Salk scientists discover critical gene activity follows a biological clock, affecting diseases of the brain and body.
New genes on 'deteriorating' Y chromosome
Decoding Y chromosomes is difficult even with latest sequencing technologies.
More Genes News and Genes Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Making Amends
What makes a true apology? What does it mean to make amends for past mistakes? This hour, TED speakers explore how repairing the wrongs of the past is the first step toward healing for the future. Guests include historian and preservationist Brent Leggs, law professor Martha Minow, librarian Dawn Wacek, and playwright V (formerly Eve Ensler).
Now Playing: Science for the People

#565 The Great Wide Indoors
We're all spending a bit more time indoors this summer than we probably figured. But did you ever stop to think about why the places we live and work as designed the way they are? And how they could be designed better? We're talking with Emily Anthes about her new book "The Great Indoors: The Surprising Science of how Buildings Shape our Behavior, Health and Happiness".
Now Playing: Radiolab

The Third. A TED Talk.
Jad gives a TED talk about his life as a journalist and how Radiolab has evolved over the years. Here's how TED described it:How do you end a story? Host of Radiolab Jad Abumrad tells how his search for an answer led him home to the mountains of Tennessee, where he met an unexpected teacher: Dolly Parton.Jad Nicholas Abumrad is a Lebanese-American radio host, composer and producer. He is the founder of the syndicated public radio program Radiolab, which is broadcast on over 600 radio stations nationwide and is downloaded more than 120 million times a year as a podcast. He also created More Perfect, a podcast that tells the stories behind the Supreme Court's most famous decisions. And most recently, Dolly Parton's America, a nine-episode podcast exploring the life and times of the iconic country music star. Abumrad has received three Peabody Awards and was named a MacArthur Fellow in 2011.