The Research: Tropical Marine Research "At the Interface of Chemistry and Biology"
Exploring the Biodiversity Triangle In his field research Crews' targets the parts of the world with the highest marine diversity. Most marine ecologists agree this is within the triangle formed by New Guinea, Singapore, and the Philippines, and Crews' team has been to numerous sites within that region including Tonga, Fiji, and Vanuatu. He has also worked extensively in the Caribbean. Currently the major focus of his research is the coral reefs of New Guinea. Working in remote regions entails a number of significant challenges to any scientist, but especially one whose work depends on long-term sample preservation, as is the case with natural products research. Even if a research boat with generator and freezer can be found, keeping samples frozen for transport back to the U.S. can be challenging if not impossible, as dry ice is not a common commodity in developing countries. Because of this, Crews has developed a simple preservation method for samples that is unique among his colleagues. In the 1980s he discovered that if freshly collected sponges are soaked in a 50% alcohol-50% water solution for 10-20 hours, and the solution discarded, the sponges can then be stored at room temperature and still contain their natural products. While in the field the group does use chromatography to ensure that bioactive compounds associated with sponges are being collected, and to help identify sponges that may be of particular interest for collections. However, Crews says they have intentionally limited high-tech experimentation while away from the lab. "We don't think of taking HPLCs or mass spectrometers with us," says Crews, "We focus on keeping our heads underwater, being in nature, and trying to learn from the ecology of the organisms we're collecting which will be relevant to chemistry we're engaged in." Exploring Chemical Diversity The main ecological question Crews' research is designed to address is: What is the ultimate source of the secondary metabolites produced by sponges? So, when his group identifies compounds from a sponge with unique chemical architectures, they attempt to determine who is responsible for actually producing the compounds, because there is a lot more in a sponge than sponge. Some of those collected are as much as 50% bacteria. Crews and his team have found evidence of astounding molecular structure among bacteria-derived compounds. One focus for the group is the mixobacteria. Like other teams, they are still working to develop methods needed to effectively culture various species in the lab. In addition, they are working to get and sequence the DNA of bacteria they cannot currently culture in hopes of manufacturing the compounds they produce by recreating their biosynthetic pathways based on genetic information. "It's going to take a lot of investigators," says Crews of this line of research, "and having one or more folks get lucky. We're hoping we'll be the lucky ones." Marine Fungi: Untapped Potential? Crews' lab was among the first to realize and prove the concept that in addition to bacteria, sponges also contain an abundance of fungi, and the group is also working to isolate fungi from marine sediments. In studying fungi, the initial hope was that they would yield a whole new paradigm in molecular structures. This work is ongoing, and the group has already made some promising finds from the roughly 100 fungi compounds they have isolated, a few of which have garnered interest from biotech companies. The challenge with marine fungi, according to Crews, is isolating and identifying fungi and related compounds that are not also among those found on land, which have already been heavily studied. Crews views tapping the potential of marine fungi as an area best suited to academic researchers such as himself who can remain focused on the issue for the long-term, as opposed to biotech companies that require much faster payoff than appears likely in this case. Crews remains hopeful in the work overall. "I believe we're at the doorstep of interesting chemistry there, " says Crews of marine fungi research, "so stay tuned. We should have breakthroughs and know whether this is going to work or not in the next couple of years." The Crews group has more recently branched into studies of bacteria and fungi isolated from marine sediments collected in both shallow and deepwater. To date the work has focused on samples collected from Papua New Guinea, Vanuatu, San Diego, and the Monterey Bay Canyon. The group uses a modified collection device they dubbed the "Crews" Missile to collect sediment samples from as deep 2,000 feet. The most Interesting Field Locations - And the Most Dangerous! Crews' research has taken him to so many unique and exotic locations, that choosing a favorite is difficult, he says. Above the water, he puts the Kingdom of Tonga at the top of his list and is especially fond of the country's music and artwork, a selection of which is displayed at his house. Underwater, he says Fiji gets the highest marks so far. One of his favorite spots is the Beqa (pronounced "Benga") Lagoon, where he first discovered the sponges from which the bengamides, a series of promising bioactive compounds, were isolated. The lagoon includes a section of spectacular, cavernous passages he compares to Manhattan side streets that are littered with sponges, gorgonians tunicates, and seaweeds. "It's been a privilege to be able to go to these areas," says Crews. As you might expect, Crews has an abundance of stories about interesting, exciting, and tricky situations in which he and his team have found themselves while in the field. One of his most memorable experiences occurred in Papua New Guinea in 1999. Around many of the country's islands, the accepted practice before diving is to spend some time in the nearest village seeking permission from the chief and offering small gifts. Though the Crews team followed this protocol, their boat was once mistaken for that of a group of tourist divers who had blatantly disregarded procedure. In retaliation, the islanders began using slingshots to hurl rocks at the Crews team, and throwing spears from approaching outrigger canoes. Crews was on the boat at the time, but several members were on the bottom diving. "So, the challenge was to go down to about 70 or 80 feet and tell divers we need to exit ASAP, " says Crews. "We were trying to figure out what the underwater signal should be for a native attack with slingshots and spears, " he says. Thankfully the group was able to escape unharmed and clear up the misunderstanding with the village and so resume collections at the site. Educational Background A child's chemistry set was Phil Crews' first exposure to the field that would ultimately become his career. He recalls as a youngster completing some successful experiments with hydrogen sulfide, also known as rotten egg gas, but did not go much further until he began college. As an undergraduate at UCLA, he became interested in Nuclear Magnetic Resonance (NMR) and in his spare time began using NMR spectra to attempt to derive compound structures. While in LA he also learned how to surf and so expanded his fondness for the ocean. He says that, rather than academic concerns, it was UC Santa Barbara's good surf spots that drew him there where he received a Ph.D. doing NMR dissertation work. His next career step took him east for a postdoctoral fellowship at Princeton. He missed the West Coast, however, and soon returned there to join the UC Santa Cruz Department of Chemistry and Biochemistry. In the 1970s, after about 4 years studying theoretically interesting molecules, he decided to use spectroscopy to explore interesting marine-based problems. One of the catalysts to this shift came when he found, in a book an undergraduate student brought to him, a chapter explaining many wondrous biological properties of sponges, but that labeled their chemistry as "unknown." He began working on sponges, but eventually had to put this line or research on hold due in large part to the inadequacy of chemistry tools available at that time. After turning his attention to seaweeds for several years, he was able to return to sponges by the 1980s and has studied their chemistry ever since. |
