In an Experience story published this past June, Matt Crossman wrote about a species of rainbow trout whose genetic origin is an enduring mystery — and an example of the biodiversity that marine biologists are just beginning to uncover. “We’re expanding our knowledge of our ignorance much faster than we’re expanding our knowledge,” marine biologist Dan Distel, director of Northeastern University’s Ocean Genome Legacy Center, told Crossman.
Recently, Crossman and Distel continued their conversation about the work of the center, which is the United States’ first public access DNA bank and research laboratory dedicated to marine life. Their conversation below has been edited and condensed for clarity.
What do you do at the Ocean Genome Legacy Center, and what is your mission?
[Humans are] having a big effect on the environment, and as a result, a lot of species are disappearing. Part of the mission of Ocean Genome Legacy is to capture the DNA from those organisms, freeze it away in our freezers, and make it freely available to researchers around the world. That can range from medical research to agricultural research to food-based research, all being done with samples from our collection.
How many samples do you have, and is there any way to even guess how many are yet out there?
We have in the neighborhood of 27,000 DNA samples in the collection— close to 5,000 species represented. It’s estimated that the marine environment could contain at least 2 million species, possibly many more. To put that in context, so far, the number of named species on Earth is just under 2 million. And the number of named species in the ocean — the ones we know about — is 240,000 to 250,000.
“Who would have thought of looking inside a clam in the ocean to find a potential medicine?”Dan Distel, Director of the Ocean Genome Legacy Project
Wow. You’re never going to run out of work to do.
No, we’re going to keep busy.
What do your freezers look like?
We’ve named them after famous scientists: Linnaeus, Darwin, Franklin. They are just like the freezers you have at home, just much, much colder — minus 84 degrees centigrade right now. At that temperature, we can keep samples essentially indefinitely, without any degradation. We have a second type of freezer, a liquid nitrogen freezer, currently at minus 182 degrees.
How is the DNA actually stored?
We have these boxes and each box contains 81 small tubes of purified DNA. We also have samples that contain tissues known as “voucher specimens.” If there’s ever a question as to the identity of any sample in our collection, voucher specimens can be used [in] the old-fashioned way of doing species identification, by shape and size and appearance.
Appearance only gets you so far, right? I learned, reporting the story, about two different species of fish: the “sculpin” and the “prickly-like sculpin.” Even an expert couldn’t tell, from just looking at them, which was which.
That is true. We have certain species that we cannot tell apart until we put them in the blender and extract and sequence the DNA. And then it’s very obvious that they’re different, but by eye, we can’t tell the difference. We presume they can tell each other apart.
So the prickly-like sculpin could swim up to the other sculpin and be like, “No, you ain’t one of us”?
Pretty much. A lot of that is through very subtle differences that they can detect, but also through chemical cues. There are chemicals, for example, called pheromones, that enable organisms to recognize potential mates and stimulate reproduction. But yeah, we know that they can tell each other apart because they do. Very often, we have species where the regions where they’re found overlap, but because they’re distinct species, we know that they don’t reproduce with one another.
How would scientists tell them apart, then?
The more we study, the more we understand what to look for. For example, we only see a portion of the visible spectrum of light. There are other organisms that see different parts of that visual spectrum. In the deep sea where it’s dark, scientists go down, shine different wavelengths of light, and suddenly realize that, hey, some of these things that look very nondescript are now glowing with very intricate patterns. And those patterns must mean something to their mates or to their predators or to their prey. They’re not there for no reason.
We observe and absorb and measure and collate the world in a very particular way. And we just assume that all animals do that. And it sounds like that, not only is that not true, but there are ways that they do it that we don’t even know or understand.
That’s right. The way we really learn about species is by comparing. For example, if you have a particular problem of how to live, say, at very cold temperature, or in dark or at high pressure — all of these common things in the ocean — different species have learned different ways to solve that problem. And when you begin to compare them, you begin to understand the basic chemistry and physics and biology that explains how they do it.
Sometimes I like to say, if a Martian came to Earth and saw an automobile, they’d have no idea what that was or what it was for. But the more cars you look at, you begin to see: Oh, well, they all have four wheels. That must do something. They all have an engine; that must do something. And by comparison, you begin to figure it out.
What has learning about the diversity of the ocean taught you about the power of life? In order for a creature to live way down at the bottom of the ocean, and for us to be so completely different, there is something powerful going on.
The thing that I always find exciting is, there’s so much that we don’t know, but it’s just beyond our reach. We can every day find something new and unexpected. For example, I work a lot with a group of organisms called shipworms. They’re bivalves that eat wood, and sailors in the old days used to be afraid of them because they would rot the hulls of their ships very quickly. There are reams of information written by the British Navy about shipworms. But we found more recently that shipworms have bacteria that live inside their cells — actually inside their cells, like an infection. Some of those bacteria help them to digest, but recently we found out that they also produce antibiotics.
Who would have thought of looking inside a clam in the ocean that eats wood to find a potential medicine? But by accident, by studying other things, we stumble across it. And we have colleagues in Utah and Minnesota who are working on various drugs that come from these bacteria, and they may have a big effect on people’s lives.