TOPICS > Science

Oceanic Expedition Uncovers Vast Genetic Diversity

March 16, 2007 at 6:40 PM EDT

RAY SUAREZ: The findings come from a global expedition that’s been compared to Charles Darwin’s sea voyages more than a century ago.

Scientists have been trawling the oceans since 2003 in search of the smallest organisms, microbes, to create a kind of microscopic marine census. The project was launched by geneticist Craig Venter, who turned his own private yacht, “Sorcerer Two,” into a floating laboratory.

Venter, already well known for his pioneering work to help crack the human genetic code, set off with his team from Halifax, in Canada on the Atlantic coast, sailed through the Panama Canal into the Pacific Ocean, heading for the Galapagos Islands and French Polynesia.

In a report published earlier this week, the team said it found millions of new genes and proteins among the bacteria and other microorganisms. The data that’s been analyzed to date has already doubled the number of known genes on Earth.

Venter and his team are now sharing the information they’ve gathered on the Internet.

Uncovering DNA codes

RAY SUAREZ: And for more about the significance of these findings and the voyage, I am joined by Craig Venter, the expedition's leader.

So we're out on the open ocean, and we take the serious high-tech bucket, and throw it over the side, and pull up water that's full of what?

CRAIG VENTER, Undersea Expedition Leader: Water, even crystal clear ocean water. We take a teaspoon of it. That teaspoon will contain millions of bacteria and tens of millions of viruses.

We've missed them because we can't see them with our own visual acuity. And when we try to culture these organisms, only about a tenth of a percent of them have ever grown in the laboratory.

So we've used the new tools that we developed for sequencing the human genome to take the DNA from these organisms in the ocean, sequence the DNA to find out, in fact, who's there and what they do.

RAY SUAREZ: Did we not know before that all that was in that water?

CRAIG VENTER: In fact, we clearly did not know. In fact, seas like the Sargasso Sea were thought to be a desert, very little life, because there was no nutrients.

So it is the new photo receptors, similar to our visual pigments in our eyes, that capture energy from the sun that allows these organisms to grow. And these are a key part of the carbon sink in the ocean for capturing CO-2.

Applications of the discoveries

RAY SUAREZ: How do all those organisms get into the water? And what are they doing in there?

CRAIG VENTER: Well, obviously, they've been there for hundreds of millions of years. In fact, we found such incredible diversity, unexpected from almost any type of study. Every 200 miles, 85 percent of the organisms and sequences were unique to that region.

So instead of this homogeneous primordial soup, it's millions of microenvironments, like miniature multi-cellular organisms involving the chemistry of the moment of that site. So they've been there; they've been evolving; they've been changing over time. And we're seeing them now for the first time by looking at their genetic code.

RAY SUAREZ: So you look at their genetic code. So, like us, and like a blade of grass, and like a fruit fly, they have a DNA sequence. What does knowing that get you to further find out about? What does that unlock for you?

CRAIG VENTER: It unlocks everything from understanding evolution better -- for example, genes that we thought were only unique to humans and mammals we're now finding go across all branches of life.

We just doubled the number of known genes that we have sequence from, so it expands the databases for everything from trying to understand how many proteins and genes we even have on our planet to finding practical uses for them.

We're trying to create bioenergy by taking some of these genes and pathways and converting, for example, sunlight into hydrogen or sugar into a burnable fuel.

We also allow now to try and understand the chemistry of the oceans, where we capture back the CO-2. We put 3.5 billion tons a year into the atmosphere. The ocean is the biggest carbon sink, over a hundred billion tons. If we can shift that equilibrium slightly, we might be able to capture back more that's actually doing real harm to our planet.

Warm, cold water differences

RAY SUAREZ: As you were taking these samples, every couple of hundred nautical miles on a long voyage, did you find that there's more stuff in cold water than warm, or shallow water than deep, or water that's close to land as opposed to the middle of the ocean?

CRAIG VENTER: What we found is each site differs from each other, but the diversity and the amount of organisms is extremely high everywhere.

But there's different ones that grow in the cold water of the North Atlantic than in the South Atlantic. The Atlantic Ocean is different than the Pacific Ocean. The fresh water of the Panama Canal is totally unique with organisms.

The most important thing we found is these photo receptors see the color of light in the region reflected by the seawater. In the Sargasso Sea, it's a deep indigo blue. The photo receptors, it's like having one eye only see blue light.

You get into coastal waters, they see green light reflected off the chlorophyll. And a single letter change in the genetic code changes one amino acid of this protein that changes the wavelength of light that these receptors see.

So we might have a huge, vast reserve of new molecules that capture different wavelengths of light that we might use to capture sunlight and unique metabolic processes.

A different view of the ocean

RAY SUAREZ: So here you've got these cells that are like the cells in the human eye. You've got these things that no one ever knew were in the ocean before. Do you look at the ocean differently now, almost like a living organism itself?

CRAIG VENTER: I definitely do. And it's hard, because our visual acuity looks like some of these places it's just the most beautiful, crystal clear water. And I constantly have to remind myself: I'm looking at billions of organisms just in that one area.

We have to change our thinking. These are the most abundant life forms on the planet. You can take all the bacteria out of the sea, and they outweigh all the plants and animals that we can see with our own eyes. It's a different view of biology and how it originated here.

RAY SUAREZ: Well, just like finding something in the Amazon rainforest or in a central African jungle, are there countries that are going to say, "Hey, Craig Venter this is part of our national patrimony, our genetic property, don't come and just take stuff out of there"?

CRAIG VENTER: Well, in fact, it is an issue. We've had to work through the State Department to get sampling permits from every country where we went out of international waters into their 200-mile limit. And we've been required to label every sequence in these public databases as the genetic patrimony of those countries where they're reserving commercial rights.

So it's a very different world than Darwin experienced, where he just traveled around on this expedition and collected species. We now have to get permission to even take a barrel of seawater.

RAY SUAREZ: Craig Venter, thanks for talking to us.

CRAIG VENTER: Great to be with you.