Stanford University News Service



Hopkins Marine Station: basic science on a living coastline

STANFORD and HOPKINS MARINE STATION -- When David Starr Jordan came to Stanford as its first president, he envisioned a seaside laboratory for the university dedicated to the academic interest closest to his own heart - the intensive study of marine organisms. The result was Hopkins Marine Station, founded in 1892 as the first marine laboratory on the American Pacific Coast. The research conducted there now ranges farther than Jordan could have imagined, to include bizarre life-forms in steaming undersea vents, schools of tuna prowling the open sea and the giant neurons of squid.

Built on a rocky headland along the southern shore of Monterey Bay and bordered by the Hopkins Marine Life Refuge, the station offers scientists and students a rich opportunity to study a complex world right outside their laboratory windows. It is one of the few scientific facilities where a sign is needed to remind the researchers: "No Wetsuits in the Library."

Located 90 miles south of Stanford, Hopkins is a branch of the university's Department of Biological Sciences. It is led by a resident faculty of eight biologists, plus a lecturer in biological sciences and two active emeritus faculty members. The station is also home to a staff of ten, plus graduate students, postdoctoral fellows and a distinguished succession of visiting scholars. An undergraduate education program offers classes in marine and general biology plus challenging opportunities to conduct field research. These courses are open to qualified students from any college or university and also to teachers of biology.

Hopkins biologists use marine organisms to study a number of fundamental questions in biology. Among other things, their work has implications for the preservation of resources; for a better understanding of human health and disease; for insights into the immune system and the workings of the brain, and for a better understanding of evolution and adaptation.


Dennis A. Powers, Professor - Director, Hopkins Marine Station
Harold A. Miller Professor of Marine Biology
Marine Biology, Biochemistry, Molecular Evolution, Physiological Ecology

Powers uses a multi-disciplinary approach to study the way that marine organisms adapt to short-term and long-term changes in environmental conditions, including temperature, salinity, oxygen, pressure and acidity. His studies of the molecular mechanisms of adaptation have provided insights into the mechanisms of evolution and the significance of genetic variation at the molecular level.

Researchers in Powers' lab are collaborating in a project to genetically engineer strains of fast-growing, disease-resistant fish and "super abalone." Powers is also developing a fish that can live in water with normally lethal levels of dissolved oxygen. If successful, this effort would provide new understanding of the molecular mechanisms that allow animals to adapt to extreme environments. It also might be useful for the aquaculture industry, where many millions of dollars' worth of fish are killed during brief periods when oxygen levels in fish ponds drop to lethally low levels.

Powers and his colleagues also use DNA fingerprinting and other molecular techniques to help fisheries biologists better manage important, potentially endangered fish stocks, such as pollock and salmon. The goal of another investigation is to determine the amount of genetic diversity in natural populations of non-reef-building corals. The lower the genetic variation, the less likely a population will be able to adapt successfully to changes in its environment. In yet another study, the researchers have shown that a 20 percent increase in ultraviolet radiation can decrease the growth rate of giant sea kelp by up to 50 percent. This research suggests that, if the ozone layer continues to deteriorate, increases in ultraviolet radiation could have a devastating effect on the marine food web.

In addition, some of Powers' graduate students are following up an earlier discovery that northern populations of a small fish called Fundulus have more lactate dehydrogenase (an enzyme that plays a key role in converting carbohydrates into energy) than do those from southern waters. They have found differences in the DNA sequences in the genes of the northern and southern populations that may account for this difference. The researchers now are studying the mechanisms responsible for regulating different levels of this and other gene products in the two populations.

Barbara A. Block, Assistant Professor
Ecological and Cellular Physiology, Molecular Biology, Biochemistry.

Block is co-director of the Tuna Research and Conservation Center (TRCC). She is an expert on the physiology of tunas and two closely related species, marlins and swordfish. She and her students work closely with the scientists and animal husbandry experts of the nearby Monterey Bay Aquarium, where the million-gallon Open Oceans exhibit is home to North America's largest school of captive tunas.

Tunas are among the world's few warm-blooded fish. By comparing them with their cold-blooded cousin, the bonito, Block's work is providing new insights into the origins of warm-bloodedness. Members of her lab are using new acoustic telemetry devices to listen to how the muscles and the heart work in captive fish at the TRCC. They want to find out whether warm fish generate more force and power with their muscles than cold-bodied species. Block and her post-docs also are working with engineers to develop portable monitoring devices that these long-distance travelers can wear for months or years in the open ocean. The tags will beam data to satellites about the position and physiology of the fish.

DNA analyses are being used in the Block lab to piece together the jigsaw puzzle of how swordfish are related to each other in oceans around the globe. The results are helping to define how best to preserve the current genetic biodiversity in swordfish populations worldwide.

Mark W. Denny, Associate Professor

Denny looks at the way intertidal organisms are designed and engineered. On the one hand, he is interested in figuring out the underlying factors that led to the ways in which mussels, crabs and kelp are designed. At the same time he keeps his eyes peeled for new solutions to basic engineering problems that nature has evolved.

Wave-swept shores are an ideal place to conduct research of this type because, next to flight, they place the strictest constraints on how organisms are designed. The Denny lab is a maze of wind tunnels, water tunnels, wave machines and a fog machine - all built to simulate and test the forces endured by creatures in the intertidal zone outside the lab's window.

Denny's studies of limpets and mussels have determined how much wave pounding they can withstand. Using basic information on the average size of waves in an area, he can calculate what fraction of mussel beds will be ripped out in a given year, a figure that is very important for scientists who are studying the community structure of intertidal communities. He also is studying the way that waves interact with kelp in an attempt to understand how these flexible and seemingly fragile plants survive.

David Epel, Professor
Cell and Developmental Biology

The sea is a hostile environment. Reproduction there is no easy task. Epel studies both the critical early events of fertilization and the methods that marine animals use to protect themselves from toxic materials at the most vulnerable stages of the life cycle. Epel's investigations of fertilization using sea urchins have added important new understanding of how cell division is triggered and how the development process is initiated within the egg.

In work that is proving applicable to the regulation of human fertility, his group also studies the means by which both egg and sperm remain dormant under most conditions and what turns on their metabolisms to enable fertilization. Sperm only become motile when they are released into the environment, while the egg only turns on its biosynthetic machinery upon contact with a sperm. Another research area is the biology of fertilization in the marine environment: There is much information about fertilization in the test tube, but little about how it occurs in nature.

Epel also studies how pollution and other toxins such as pathogens and ultraviolet radiation affect embryo development in the ocean. Using marine worms, his group also is studying mechanisms that organisms use to physically expel toxic materials. Although this is an organism's first line of defense, it has not been studied nearly as extensively as the immune system and other defensive systems that organisms employ for this purpose.

William F. Gilly, Associate Professor
Neurobiology, Cell Biology, Behavior

Understanding how individual nerve cells control sophisticated behaviors is the goal of Gilly's research. He approaches this problem by studying how the nervous systems of newly hatched squid grow in complexity as the animals respond to their environment. More specifically, he measures these changes in special giant nerve cells that are active when squid flee from predators using jet propulsion. Such responses are controlled by the way the squid's neurons transmit information in the form of electrical impulses. The electrical characteristics of the nerve cells, specifically their excitability, are strongly influenced by the common sodium and potassium ions that flow into and out of the cells through special protein gates, called channels.

In the brains of mammals, there are probably hundreds of different kinds of channels located in tiny nerve cells. The giant neurons of the squid are much simpler, however, with only one or two types of sodium and potassium channels. Gilly and his colleagues have cloned the genes that express these ion channels. His students have developed several methods to map different types of squid channel proteins and are exploring how these maps are established. They also have discovered that the giant neurons involved in escape responses also play a role in prey capture: When baby squid are raised exclusively on slow, easy-to-catch prey, their neurons fail to develop normal excitation patterns. As adults, not only do the squid have trouble catching faster prey but they also respond poorly to disturbing stimuli. A major focus of Gilly's work is to determine how and when genes are turned on and off to cause these changes in excitation patterns.

R. Paul Levine, Research Professor
Biochemistry and Molecular Biology

Levine's current research on the genetics and biochemistry of symbiosis and parasitism has led him to tests of a genetic vaccine for fish. The project stems from his studies of a bacterium that normally lives benignly in the kidneys of salmon. When the animal is put under stress, the bacteria divide, ultimately killing the fish. The disease has decimated a number of different fish populations, including the Chinook salmon in the Sacramento River. So Levine and his colleagues are testing a gene vaccine, inserting strands of DNA containing genes that encode bacterial proteins. The purpose is to generate antibodies and other cellular protective responses against the bacteria. To get the DNA into the fish kidneys, he wraps them around microscopic particles of gold, and shoots the gold into the fish.

In a second, related area of research, Levine's group is studying the symbiosis between sea anemones and algae. The microscopic green plants live between the cells of the anemone and feed on chemicals that the anemone provides. In return, they produce other chemicals by photosynthesis that the anemone cannot provide for itself. Most information about such relationships is limited to the symbiosis of nitrogen-fixing bacteria and their host plants. Levine's efforts center on identifying the genes and gene products involved in initiating, maintaining and causing this symbiosis to work - and to break down under stress. So far, the researchers have identified a number of genes and gene products that appear to be associated with the symbiosis and are in the process of sequencing the genes to determine the structure and function of the proteins that they encode.

George N. Somero, Professor
David & Lucile Packard Professor of Marine Biology

Somero joined the Hopkins faculty in 1995 as the faculty's unanimous choice for the new Packard Chair in Marine Biology. Internationally recognized for his work on how marine organisms adapt to extreme environments, he seeks his research subjects in the deep sea, the polar oceans and in the hydrothermal vents on the deep ocean floor. The ability to thrive in an environment with extreme temperatures, pressures or chemical conditions depends on adaptive variations in proteins. Somero's group has shown that only minor differences in the prevailing temperature of an organism's habitat are sufficient to favor evolutionary changes - and that organisms can adapt to a new environment with minor changes in protein sequence

Most studies of molecular evolution have emphasized proteins and nucleic acids, but Somero also studies the "micromolecular" parts of cells, the protons, inorganic ions and organic molecules in the cell fluid. He and his colleagues have shown why intracellular pH varies with body temperature, and why sharks accumulate high concentrations of urea within their cells.

Stuart H. Thompson, Associate Professor
Neurophysiology, Biophysics, Signal Transduction

Nerve cells process information in two different ways: e