The Research: Marine Natural Products Research
The Move to Marine Microbes After decades working with macroorgansims such as corals, Fenical shifted to focus mainly on microorganisms. To appreciate the significance of microorganisms to drug discovery, Fenical points to the discovery of penicillin in 1929 by Alexander Fleming. "This was perhaps the single most important event in the history of medicine," he says, because penicillin saved hundreds of millions of lives and spurred on the discovery of other antibiotics that collectively revolutionized medicine. "When you look at that, you realize that one of the most important areas, and perhaps the single most productive area for the discovery of drugs, has been to examine the microscopic world," he says. Microorganisms in ocean sediments, especially in the deep sea, are very closely related to those from the soil that have yielded revolutionary drugs. Nonetheless, the marine sediments were historically unexplored for biomedical potential and the presence of microorganisms of biomedical interest was often doubted. Fenical's explorations, however, have shown this resource's great potential. Not only has his team isolated important potential drugs from deep sediments, they have also found incredible diversity. While microorganisms were once thought to be spread somewhat homogenously throughout the deep sea, research by Fenical and others has shown that even though microorganisms could in principle migrate anywhere in the oceans, they do not, for reasons that are not yet clear. Instead, in many cases the organisms seem to be adapted to very specific places. The microorganisms on the surface of the ocean are different from those on the bottom, and every 150 feet or so of depth change is associated with microbial changes. "If you think about that, coupled with the vastness of the surface of the ocean, that's one of the most exciting points about developing microbial resources," says Fenical. "The number of resources for the discovery of a pharmaceutical product from these microbes is an enormous figure. We're just touching the surface of this vast resource." Sediment Collection Devices A critical challenge Fenical and his colleagues faced once the potential of deep-sea sediment microorganisms became clear, was how to collect samples, as no appropriate sampling devices existed. Oceanographers had been collecting sediment samples for many years, but the tools they had developed were not appropriate for rapid replicate sampling. Using existing equipment scientists were able to collect at best only a few deep samples in a day, but because sediments are typically quite patchy, multiple samples were needed to ensure that a reasonable cross section of microorganisms present could be collected. Another challenge was that existing equipment had to be deployed from ships, which are expensive to operate and not readily available in remote areas. So, Fenical and his team began to develop miniaturized portable sampling tools that allowed them to collect a large number of samples in a single day from whatever boat might be available. They began by modifying simple devices designed for collecting lake sediment samples that would freefall then collapse on impact with the bottom to grab a sample and then be retrieved. By adding weights and high-tech lines that are strong but lightweight, the group is now able to take samples down to about 3,600 feet. They have adapted an electric fishing reel for retrieval. The devices can be easily transported on a plane and deployed from small boats, allowing Fenical global access. Early on the group collected samples in the tropical Atlantic and near their home base in La Jolla, where deep canyons are found close to shore. They have since sampled at locations such as Palau, Guam, Hawaii, Mexico, the Egyptian Red Sea, and Australia. They have also developed similar devices that take core samples, allowing examination of deeper sediments and stratified changes in microbial communities from the aerobic surface sediments to the anaerobic sediments farther down. However, these corers require retrieval by more sophisticated devices. Fenical ultimately hopes to be able to collect samples from much greater depths, because the ocean is on average about 12,000 feet deep. To do that, his team is developing a remote sampling device that can be dropped without tether then retrieved using a timing device or weight release to return it to the surface. Ownership Like many biomedical researchers, Fenical is concerned about the ownership issues of working in other nations' waters as well as international waters. Determining who owns what is a difficult problem, he says. Developing countries especially are now highly focused on intellectual property and natural products and maintaining some rights to these resources, which he feels has been somewhat counter-productive to advancing the science. The American approach, has been to view natural product resources as open, so, especially in California, foreign investigators are not precluded from examining resources. Working with sediment organisms has taken Fenical at times into international waters, where no one really owns the resources. "I think this might be the first time in the history of natural drug discovery where there are free drug producing organisms without any nationalism being involved in this discovery and it's interesting to think about that and how we are going to develop those discoveries." How to Raise a Deep-Sea Microbe Early on in his lab's microbial work, Fenical turned to the pharmaceutical industry to learn how to culture organisms. However, it soon became apparent that the media and techniques typically used would not work with deep-sea microorganisms. What everyone had failed to realize was the fundamental differences between terrestrial and marine microbes, especially the differences in nutrients available to each. In the sea, unlike on land, there is no glucose, peptone or, with few exceptions, horse hooves-- all products used in common media for culturing terrestrial microorganisms. It took Fenical's team years, but they have developed completely new media based on such products as crab or fishmeal and seaweed. Besides determining the right nutrients to provide marine microorganisms to encourage their growth, the researchers had to determine what levels to provide. Classic microbiology called for 5-10% carbon in growth media, but many organisms in the sea are adapted to very low levels of nutrients, so the team had to scale back nutrients in their growth media accordingly. After working for years at what Fenical calls very basic environmental microbiology, the team is now very effective at growing the kinds of organisms they want. "Learning what's out there, and how they continually survive, that showed us the way to do it," says Fenical. Pioneer Days As one of the pioneering founders of the marine natural products fields, Fenical struggled during the 1970s against the widespread perception that there was little if anything of medicinal value in the oceans. "It was discouraging to press forward because of that," he says, "and difficult for young people who had a vision to look at this field to get a job." Nonetheless, a handful of researchers, mainly chemists, persevered. In addition to doubting the ocean's biomedical importance, some potential funders suggested that the work was more about lounging and diving in the tropics than drug discovery. To overcome this hurdle, Fenical and colleagues in about 1979 invited one funding agency representative along on an expedition to Tres Marias on Mexico's Pacific side. The reprentative ended up in a near shark attack, averted when another diver shoved a camera into the shark's mouth and hit him several times with a club. After that, says Fenical with a laugh, he consistently attested that the field was dangerous, but, more importantly, he came away from the trip with a clear understanding that the researchers were working very hard despite their enviable field locations. As the field progressed, chemists like Fenical, who were learning needed biology as they went, were making fascinating discoveries. "Very slowly, we began to see the presence of molecules that no one had seen before," says Fenical, "compounds that contained unusual elements even. " For example, the researchers found that bromine, a noxious gas, was actually incorporated by enzymatic processes into organic molecules in the ocean, largely as molecules that provided defense. Finally, by the 1980s, thanks to several drug discoveries, it was becoming clear that the ocean was indeed an important biomedical resource. By the end of that decade, says Fenical, the pharmaceutical industry began to make some investments in the field, mainly by collaboration. Fenical points to growing support, for instance from the National Institutes of Health, which recently awarded his lab a major marine biotechnology training grant, as a sign that recognition for the importance of marine natural products is now growing. "I'm happy after some 30 years or more that now we're really looking at a resource that's understood, appreciated and being developed at a rapid pace," he says. Success Stories One of Fenical's earliest successes was the discovery and development, along with Bob Jacobs of a group of unique anti-inflammatory agents called the pseudopterosins, which were isolated from the soft coral Pseudopterogorgia. Though still in development as a topical pharmaceutical product, the pseudopterosins were licensed by the Estee Lauder company, which developed a series of popular skin care products based on them called Resilience. Production of the products requires collection of the coral from the wild, a fact that initially caused dismay among some environmentalists, Fenical says. However, once he and his colleagues had the opportunity to explain the collection process, the work was used as an example of how conservation-sensitive new products could be developed from coral reefs. Rather than destroying the whole coral, the collections involve pruning or "feathering" about 80% of the corals, leaving a viable branchlet on the reef that, like a plant, regenerates, often to a more luxurious state than prior to pruning. More recently, Fenical's lab group has developed two potential cancer treatments from compounds produced by marine microorganisms. The first, called Halimide, was isolated from a microorganism that lives on marine algae. It is a fast-acting anti-cancer agent with the unique property of entering into a tumor's blood vessels and causing them to collapse, therefore removing the blood flow and causing the tumor to die within a few minutes. A second product, called Salinosporamide A, is proving more potent than most anti-cancer agents on the market, Fenical says. It targets a small bundle of enzymes in the middle of cancer cells called the proteosome and inhibits their function dramatically, even at sub-nanomaolar levels of compound. Salinosporamide A is a product of a newly discovered genus of microorganisms called Salinospora, that live in the deep ocean sediments. Both these products are licensed to and being developed by a small San Diego biotechnology company called Nereus Pharmaceuticals, which Fenical helped to found and currently consults for. A key focus of Nereus is the identification of drug candidates derived from marine microbes. These lead products are expected to reach clinical trials soon. Near-Fatal China Expedition Having traveled the world in search of marine natural products, Fenical has been involved in a number of tricky situations, but none so memorable as one that occurred on an expedition to China. He and colleagues had been invited to collect samples there in the early '80s, long before anything resembling free scientific exchange between the U.S. and China had been established. There were no hotels, so upon arrival in Beijing, they had to stay at rooms in the Communist party headquarters. They worked from Hainan Island, which at the time was almost completely isolated and unknown but would in 2001 become the focus of international attention as the landing site of a U.S. surveillance plane damaged during a collision with a Chinese jetfighter. While collecting algae samples working from Chinese fishing boats not far offshore, Fenical recalls hearing an enormous explosion and his ears ringing. He and his dive buddy looked at each other in confusion but neither knew what had happened. They thought perhaps something had happened to their scuba equipment but could find no problems, so they surfaced. About 50 yards away, another part of the team was working from a separate boat. Fenical and his buddy soon learned that Chinese fisherman using dynamite, a relatively common practice in some parts of the world for stunning fish for collection, had dropped dynamite near two of the divers. At the time Fenical surfaced, both were laying unconscious on the bottom. One of the wounded divers woke up and had the presence of mind to grab the mask that had blown off him, clear it, and find his regulator. He then grabbed his still unconscious partner and took him to the surface and got him breathing again. The team took them quickly to the island, but the hospital there was extremely primitive and lacked the medicine or expertise to treat the divers' injuries. The most critically wounded diver had only 10-15% of his lung function and the team knew it had to get him to better facilities in Hong Kong, some 300 miles away. Because of the nature of the injuries, an embolism was a serious concern and so the team felt they could not fly the diver out on an airplane because the altitude change could cause problems. So, they instead set about finding a way to get him off the island by helicopter, which proved an exceedingly complex task. As "luck" would have it, there was a pair of military helicopters on the island and a pilot there offered to do the flight, but for days made excuses why they would have to postpone departure. Finally, the team realized that the helicopters were not even functional but instead simply painted nicely to give the appearance of military capabilities. Finally, with help from the British Embassy in Beijing, the researchers made arrangements with a British Petroleum exploration team working nearby to come get the diver in its huge jet helicopter. Nothing like the sophisticated craft had ever been seen on the isolated island, so thousands of residents met it at the airport to see the spectacle. Fenical and his team had a difficult time just getting the injured diver to the helicopter through the crowd, but clearing the crowd for takeoff proved impossible. The pilot had to simply start the engine, whose blast knocked quite a few villagers down, but no one was injured. The drastic measures proved justified as the diver, treated in Hong Kong by a doctor trained in Belfast who specialized in bomb blast victims, completely recovered. Education William Fenical received a BS in biochemistry from California State Polytechnic University, and an MS in organic chemistry from San Jose State University. After receiving his Ph.D. in organic chemistry from the University of California, Riverside, Fenical worked briefly at the Shell Development Co. in Emeryville, Calif., and also did postdoctoral research at the University of California, Riverside while teaching at San Bernardino Valley College. He arrived at Scripps in 1973 and has remained there ever since. |
