The ocean benefits human health and well-being in immeasurable
ways. The nutritional benefits of eating fish, rich in protein and omega-3 fatty acids, make the ocean an indispensable—but not unlimited—source of healthy food. Ocean science is revealing many other ways the ocean can benefit human health, from providing new sources of drugs to helping unravel many of the mysteries
of human disease.
The ocean is the most promising frontier for sources of new drugs.
In 1945, a young organic chemist named Werner Bergmann
set out to explore the waters off the coast of southern
Florida. Among the marine organisms he scooped from the sand that day was a Caribbean sponge that would later be called
Cryptotethya crypta. Back in his lab, Bergmann extracted a novel compound from this sponge that aroused his curiosity.
The chemical Bergmann identified in this sponge, spongothymidine, eventually led to the development of a whole class of drugs that treat cancer and viral diseases and are still in use today. For example, Zidovudine
(AZT) fights the AIDS virus, HIV, and cytosine arabinoside (Ara-C) is used in the treatment of leukemias and lymphomas. Acyclovir speeds the healing of eczema and some herpes viruses. These are just a few examples of how the study of marine organisms contributes
to the health of thousands of men, women, and children around the world.
New antibiotics, in addition to new drugs for fighting cancer, inflammatory diseases, and neurodegenerative diseases (which often cannot be treated successfully today), are greatly needed. With drug resistance nibbling away at the once-full toolbox of antibiotics, the limited effectiveness of currently available drugs has dire consequences
for public health.
Historically, many medicines have come from nature—mostly from land-based natural organisms. Because scientists have nearly exhausted the supply of terrestrial plants, animals, and microorganisms that have interesting medical properties, new sources of drugs are needed.
A cone snail uses its
powerful venom to kill
a fish.
Prialt, an effective
medication for managing
chronic
pain in AIDS
and cancer patients, was
derived from
the venom
produced by this type of
snail. (Image
from Kerry
Matz, University of Utah,
Salt Lake City)Occupying more than 70 percent of the Earth's surface, the ocean is a virtually unexplored treasure chest of new and unidentified species—one of the last frontiers for sources of new natural products. These natural products are of special interest because of the dazzling diversity and uniqueness of the creatures that make the sea their home.
One reason marine organisms are so interesting to scientists
is because in adapting to the various ocean environments,
they have evolved fascinating repertoires of unique chemicals to help them survive. For example, anchored to the seafloor, a sponge that protects itself from an animal trying to take over its space by killing the invader has been compared with the human immune
system trying to kill foreign cancer cells. That same sponge, bathed in seawater containing millions of bacteria, viruses, and fungi, some of which could be pathogens, has developed antibiotics to keep those pathogens under control. Those same antibiotics could be used to treat infections in humans.
Sponges, in fact, are among the most prolific sources of diverse chemical compounds. An estimated 30 percent of all potential marine-derived
medications currently in the pipeline—and about 75 percent
of recently patented marine-derived
anticancer compounds—come from marine sponges.
Marine-based microorganisms are another particularly
rich source of new medicines. More than 120 drugs available today derive from land-based microbes. Scientists
see marine-based microbes as the most promising source of novel medicines from the sea. In all, more than 20,000 biochemical compounds have been isolated from sea creatures since the 1980s.
Because drug discovery in the marine frontier is a relatively
young field, only a few marine-derived drugs are in use today. Many others are in the pipeline. One example
is Prialt, a drug developed from the venom of a fish-killing cone snail. The cone snails produce neurotoxins
to paralyze and kill prey; those neurotoxins are being developed as neuromuscular blocks for individuals
with chronic pain, stroke, or epilepsy. Other marine-derived drugs are being tested against herpes, asthma, and breast cancer.
The National Research Council report
Marine Biotechnology in the Twenty-First Century (2002) concluded that the exploration of unique habitats,
such as deep-sea environments, and
the isolation and culture of marine microorganisms
offer two underexplored opportunities
for discovery of novel chemicals with therapeutic
potential. The successes to date, which are
based upon a very limited investigation of both
deep-sea organisms and marine microorganisms, suggest a high potential for continued discovery of new drugs.
Marine organisms provide models for understanding human biology.
Among the most fascinating aspects of ocean science is the use of marine creatures as models for unraveling the mysteries
of basic biochemical and physiological processes.
Scientists have made many remarkable discoveries by studying marine life. For example, the big purple slug offers researchers clues about learning and memory. The toadfish teaches lessons about balance and equilibrium. The spiny dogfish shark and the horseshoe crab provide a glimpse of the mechanics of vision.
Study of such animals as sea stars, sharks, and sea squirts has enormously enhanced our understanding of how the human body fights diseases. Likewise, studying sea urchins has revolutionized understanding of how cells divide,
which is paving the way for exciting new research into the diagnosis and treatment of cancer.
These are just a few of the marine organisms that have had a powerful influence on medical research. Using marine animals as models of human physiological processes
is helping researchers better understand and treat a wide array of diseases and offer the potential to decipher
many more.
Case Study: Bioluminescent bacteria from the sea shed light on some human diseases.
The mysteries of nature are typically unraveled through detailed investigations designed to answer a specific question. Sometimes, however, amazing revelations come about unexpectedly. Such is the story behind an intriguing bioluminescent bacterium named
Vibrio fischeri.
The Hawaiian bobtail squid
has a unique mutually
beneficial (symbiotic)
relationship with the
bioluminescent
bacterium
Vibrio fischeri. (Image
from
M. J. McFall-Ngai and
E. G. Ruby, University
of
Hawaii; National
Science Foundation)Vibrio fischeri enjoys an exquisite, mutually beneficial (symbiotic) relationship with the Hawaiian bobtail squid as well as other marine animals. By producing light, the bacterium helps its host lure prey, scare enemies, or attract mates. In return, the host provides the symbiotic bacteria with nutrients.
Vibrio fischeri helped scientists unravel the phenomenon of "quorum sensing," which has ultimately led to a remarkable new strategy for combating bacterial infections. Quorum sensing describes the phenomenon of how bacteria count, or sense, the abundance of fellow bacteria. In the case of
Vibrio fischeri, the bacterium will only emit light when they are dense enough to make a difference in providing light for the host squid. When a quorum of
Vibrio fischeri is reached, they signal each other to manufacture the enzyme that makes them glow in the dark.
Unfortunately, quorum sensing in other types of bacteria are also responsible for many of the diseases that plague humankind. They cause cholera and food poisoning, and infiltrate the lungs of children with cystic fibrosis. When disease-causing bacteria reach a quorum they form slimy, adhesive biofilms and produce toxins, repelling immune responses and making people sick.
Along with an understanding of how quorum sensing bacteria make people sick, however, comes new insight on how to treat bacterial infections. Researchers have developed an entirely new class of antibiotics that can disrupt the signaling system of microbial communities or disperse biofilms after they form. Best of all, because these drugs do not directly kill the bacteria, the bacteria may be less likely to develop resistance.
These and other studies at the forefront of drug discovery for the twenty-first century had their genesis
in a microbial phenomenon discovered serendipitously through the study of marine organisms. Just think: What other surprises might come from the sea?
Marine products are being used as research tools and in industry.
Aequorin is a
bioluminescent compound
found in
some jellyfish.
Scientists can use this
compound
to
illuminate biological
processes. (Image from
Dr.
Osamu Shimomura,
Marine Biological
Laboratory,
Woods Hole,
Massachusetts)Another crucial application of marine products is their use as research tools. Some marine products, for example,
allow scientists to "see" inside a cell by means of proteins that glow in the dark. In the laboratory, these fluorescent proteins help researchers track biochemical processes and understand disease. Aequorin, a bioluminescent
compound found in some jellyfish, was used to illuminate the calcium activation wave that occurs when a sea urchin egg is fertilized. Fluorescent marine compounds,
such as the green fluorescent protein found in
squid, are widely used in biomedical research to diagnose
diseases, to study cellular processes essential to cancer research and to monitor genetic modification of organisms. Such fluorescent proteins can illuminate processes
that would otherwise require complex biochemical measurements in order to be observed.
In
addition
to
their
value
as
research
tools,
a
number
of
marine-derived
products
are
already
in
use
in
agriculture,
in
industry, in
cosmetics,
and
even
in
nutritional
supplements.
For
example,
organic
fertilizers
made from seaweed extract and fish emulsion serve a role in sustainable agriculture, while an exceptional adhesive made by the common blue mussel
Mytilus edulis improves
the adherence of paint. An anti-inflammatory chemical from the sea fan is used in Estée Lauder's skin care product Resilience. A compound called docosahexaenoic
acid (DHA)—a fatty acid essential for proper mental and visual function—was discovered in a marine microalga,
Cryptocodinium cohnii. This compound currently
is marketed as a nutritional supplement in baby formula in more than 0 countries around the world.
Because marine organisms have evolved a variety of unique chemicals that are not found among land creatures,
the sea presents a rich source of tools for improving
our understanding, not only of ocean environments, but also of human health and well-being.
Spotlight: The Surprising Squid
Photograph from NOAA.One of the biggest surprises in using animal models has come from the nerve
cells of the squid.
This animal's nerves are so enormous—an estimated
1,000 times larger than those of vertebrates—they were not immediately
recognized as nerves.
Because of their incredible size, scientists can easily insert electrodes directly into the nerve cells, allowing them to study the cells'
electrical properties.
These studies have opened the door to many medical
breakthroughs in diagnosing and treating nerve disorders.
Scientists face challenges in exploring unique ocean habitats.
The ocean is the most promising source of new drugs, yet there are multiple challenges in marine exploration. At the heart of the challenges to ocean science lies the problem of the rights of a country to its genetic resources,
in general, and the intellectual property rights of commercially promising discoveries, in particular. Complex
legal and political issues involved with collecting marine resources in the territorial waters of other countries
can present a major obstacle for researchers.
Another challenge that researchers face is obtaining a sufficient quantity of new marine-derived chemicals. On one hand, scientists need a sufficient quantity to determine whether a new chemical has medical potential.
On the other hand, protecting marine natural resources is essential. Exploitation of marine plants, animals, and microorganisms must be avoided to ensure that marine ecosystems and populations are not adversely impacted. The National Research Council report
From Monsoons to Microbes: Understanding the Ocean's Role in Human Health (1999) recommends that scientists pursue new ways to produce marine chemicals in a sustainable manner,
such as aquaculture, cell culture, and recombinant (molecular) techniques, to avoid depleting
natural populations of marine
organisms.
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