A New Kind of Sea Map

Researchers peer into organisms in the search for molecules with therapeutic promise

Over the years, researchers at Scripps Institution of Oceanography at UC San Diego have employed all sorts of maps of the ocean, from the seafloor bottom to oceanic currents.

Now a new type of map is emerging through collaborative research conducted in Scripps laboratories at the Center for Marine Biotechnology and Biomedicine and the UCSD Skaggs School of Pharmacy and Pharmaceutical Sciences. William Gerwick of Scripps and Pieter Dorrestein of the UCSD Skaggs School are using a new technology to develop molecular-level "maps" of marine organisms, depicting where organic compounds might be discovered for potential new drug products for treating human diseases.

The scientists, describing their achievements in papers published in the journals Proceedings of the National Academy of Sciences and Molecular Biosystems, probed marine organisms using an emerging technology called MALDI-TOF (Matrix Assisted Laser Desorption Ionization-Time of Flight) imaging mass spectrometry to decipher the inner molecular machinery within sea creatures.

The method could help researchers understand where natural compounds come from even when nature presents a daunting array of possibilities. In the case of marine sponges, for example, researchers often have trouble resolving where beneficial molecules are created their so-called "biosynthetic origins" and if therapeutic compounds are manufactured by the sponge, bacteria within the sponge, or through a chemical combination of the two for symbiotic purposes.

"Sea hares, for example, eat cyanobacteria (blue-green algae) and we know for a fact that they assimilate their chemistry," said Gerwick. "With sponges, there are communities of organisms living within them. What we need to find out is, within those communities, who really possesses the genes to make the critical compounds?"

Using the new technology, the researchers successfully created algae and sponge maps, allowing them to pinpoint clusters of molecules, some of which have promising therapeutic properties.

"Ultimately, we need to know who holds the genes that produce the promising compounds," said Gerwick. "That's a fundamental question with lots of implications. It's been very difficult to answer, but now we are showing that mass spectrometry offers some new ways to interrogate these kinds of issues."

—Mario C. Aguilera

 May 2008