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Women in Science Learning Series

JudySakanariParasite Sleuth

by Mary Knudson

Science Can Be for You.

This series of learning kits introduces you to women who have madescience their career. The kits are produced by the University of Ne-braska State Museum in Lincoln, Nebraska. The entire series has beenfunded by the Howard Hughes Medical Institute.

Project production is directed by Judy Diamond with the collaborationof Gary Hochman, Michael Winkle and Joe Turco of Nebraska Educa-tional Telecommunications, Suzanne M. Gardner, Rayna Collins,Beth Schenker, Amy Spiegel, and Mary Knudson. We wish to give spe-cial thanks to Scott L. Gardner, Mark St. John, Roger Bruning, MarianLangan, Dana Esbensen, Rosemary Thornton, Edith Meints andMonica Norby. Most of all, we wish to express our gratitude to JudySakanari for the many hours she contributed to this project.

AuthorMary Knudson

DesignerRayna Collins

Project DirectorJudy Diamond, Ph.D.

Produced byUniversity of Nebraska State Museum

Funded byHoward Hughes Medical Institute

Copyright 1997

University of NebraskaLincoln, Nebraska

Permission is given to educators to reproduce all pages in this bookletfor classroom or training purposes.

A skinny, nine-year-old Japanese-American girl with shortstraight black hair walked down a slope to the creek where she and hertwo older brothers liked to go fishing. As she got close to the pier, shesaw a dead catfish floating in the water. Why had the fish died? Curiositygot the better of her. She picked up the catfish, pulled out a pocketknife she had borrowed from her Dad, and slit the fish open. Then shestood there staring in amazement at the fish’s insides.

The little girl, Judy Sakanari, grew up to be a scientist at the Univer-sity of California at San Francisco where she studies parasites that arefound in fish. A parasite is an animal that lives on or inside another ani-mal known as its host, and is dependent on the host for its food to sur-vive. As a nine-year-old, Judy didn’t know what a parasite was or what itlooked like when she opened up that catfish. But now she regularly ex-amines fish for parasites. One parasite she studies is a worm about aninch long that is found in fish.

Many animals have parasites. Dogs and cats can have parasites liketicks and fleas on their skin and roundworms and tapeworms inside.Humans can also get infected with parasites. “Basically I am interestedin studying parasites and the relationships of the parasites with theirhosts,” Judy said. “One of the larger questions I am interested in answer-ing is how parasites cause disease in humans.”

Unlike the relationship between a parasite and its host, some rela-tionships among animals are mutually beneficial. That means eachneeds the other, but each also helps the other. Judy gives one example ofa “cleaning station” where shrimp position themselves on rocks: “A fishwill come by and just open its mouth, and the shrimp will start pickingthe debris, bacteria, and parasites off the fish’s gills and off its skin.That way it benefits the fish because it’s getting cleaned, and the shrimpalso benefits because it’s getting a meal.”

However, the relationship parasites have with fish or animals is notmutually beneficial. The parasite benefits from living off its host, but thehost often is harmed by the parasite. For example, parasites can causelarge ulcers in the stomachs of marine mammals. They can also make

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pets and people very sick.Looking back to her years growing up, it’s hard for Judy to say when

her natural ability for learning science turned into a desire to become ascientist. She was always curious about fish, birds, insects, snakes andplants and wanted to learn more about them. In fifth grade, Judy’s par-ents bought her a toy microscope. She would hunt around in the refrig-erator for something to peer at under the microscope. She discoveredthat green onions have tiny cube-shaped cells. She examined strands ofher hair and even picked a scab to look at her blood under the micro-scope lens and saw her very own red blood cells!

Judy also liked to do experiments. In sixth grade she had a chemis-try set, and tried to do an experiment in class demonstrating acids andtheir opposites, alkalies or bases that neutralize acids. The experimentdidn’t work that day, but Judy didn’t get upset. Experiments workedsome days and not other days, and she kept on creating them. She alsobegan making science notebooks, often illustrating them by cutting pic-tures out of the National Geographic.

2

Judy with her

girlfriends at

age 12

3

Judy’s parents.

Growing up, Judy enjoyed playing softball, riding her bike, swimming and iceskating. She took ballet and violin lessons and became really good at playing the violin.She especially liked playing in the school orchestra with her friends.

When she was 12, Judy’s family moved from Glen Burnie, Maryland,to San Rafael, California, which is about 20 miles north of San Francisco. Her par-ents and two brothers, Gene and Byron, were born and raised in Califor-nia and her family wanted to move back there. It was always home tothem, even though her parents had both felt the impact of World War IIpersonally while living in California.

“In 1942, the U.S. government declared that all people of Japanese-American descent had to relocate to an internment camp, even thoughthey were loyal Americans,” Judy explains. When Judy’s mother was 18years old, she and her family were relocated from their home in the cen-tral valley of California to camps set up for American citizens of Japa-nese descent. Judy’s mother lived in the camp for three years until thewar ended. Judy’s father’s parents were also made to live in the campsduring the war. Like many other men of Japanese-American descent,Judy’s father felt it was necessary to show his loyalty to the United States,so he joined the army. He became an officer, and after retiring from the

A plate of sashimi prepared by Judy after carefully checking for parasites.

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military, worked in San Francisco for the federal government. As a stu-dent he had an interest in science and mathematics. Judy’s mother wasan elementary school teacher and later worked for the federal govern-ment. She enjoyed oil painting, flowers and cooking, and encouragedJudy’s appreciation of art and music.

Moving to California was an eye-opening experience for Judy. Shewas very surprised to discover that many Asians lived in California. Therewere not many Asians living in Glen Burnie, and sometimes children inher neighborhood rudely told Judy she looked different. But in the SanFrancisco Bay area there were many public reminders of her Japaneseancestry. There were many Asian students on university campuses, andthere were Asian restaurants and cultural festivals to attend. Judy learnedto eat various kinds of Asian food. Her family enjoyed the Japanese dishcalled “sashimi” which is sliced, raw fish. Once when her mother wascleaning a huge striped bass her uncle had caught off one of the beachesof San Francisco, Judy noticed a tiny coiled-up worm inside the fish.That worm was Anisakis (pronounced ann-is-sack-is) – one of the twoparasites she would grow up to study as a scientist!

Judy never thought about becoming a research scientist when she was growingup, because she had no idea what a scientist did. It was in college that she had to de-cide whether to pursue music or science, and science won out. At the University ofCalifornia at Berkeley Judy took a course in the physiology of aging that really inter-

Anisakis worm on a piece of raw fish.

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ested her. So she majored in physiology, the science that studies how living organismsfunction. Thinking she wanted to teach science, she went on to get a master’s degree inphysiology and biology at San Francisco State University.

Judy’s first job after graduate school would set the course for the rest of her lifein more ways than one. She got a job as a biologist studying the effects of pollution andparasites on the striped bass in California waters. There she met the man she wouldmarry, Mike Moser, the fish parasitologist working on the same project. He encour-aged her to continue studying parasites. When she first watched Mike working, Judywas astonished to see him put worms on his bare hands. She wondered how he coulddo that. Now, she finds herself doing the same thing when she works with worms.Mike, who had a doctorate degree in parasitology, told Judy stories about how intrigu-ing parasites can be — how good they are at avoiding being killed by the host’sdefense system. “There is a parasitic worm that can live in a person’s blood foryears,” Mike told Judy. “The host doesn’t recognize it as a foreign object, like a splin-ter, because the parasite coats itself with host molecules (the host’s own substances.)That way the host doesn’t react to the parasite because the host thinks it’s just part ofitself — like a wolf in sheep’s clothing.”

Judy went back to school to get another degree, this time her Ph.D (Doctor ofPhilosophy.) She continued working with parasites. She took a position called a

Judy and a colleague at work in her laboratory.

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“postdoc” — meaning after the doctorate degree — a period of research and traininga young scientist enters after receiving a Ph.D. Judy did her postdoc in the laboratoryof Dr. James H. McKerrow, chair of the pathology department at the University of Cali-fornia at San Francisco. Dr. McKerrow was Judy’s advisor. In the pathology depart-ment, medical doctors examine tissues to find out if they are diseased and scientistsstudy processes that cause disease.

Almost every scientist wants to have his or her own laboratory. Thatway, you’re your own boss. You decide what research projects you willpursue. But to do that, you have to have money to pay salaries and buysupplies and equipment. So you apply for grants from the federal gov-ernment and other organizations. “A scientist has to work very hard toget these grants because of the competition for the limited funds,” Judypoints out. The grants help the head of the laboratory hire young scien-tists to do part of the research. Eventually, scientists publish the resultsof their research in journals so that other scientists and interested peo-ple can learn what they found out.

Judy is now the head of her own lab. She has several other researchers in herlab, and now she has become an advisor to collegestudents, medical students, graduate students, postdocs and scientists who visit from

Students helping in Judy’s laboratory on “Take Your Daughter to Work Day.”

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other countries. She trains students by showing them her work and helps young sci-entists with their experiments. During the annual Take Our Daughters to Work Day,Judy talked to children 7 to 15 years old about parasites and explained what it's like towork in a science lab.

Judy’s lab studies the biochemistry and molecular biology of para-sites. She and the scientists in her lab work with the parasites’ proteinsand DNA (deoxyribonucleic acid), the basic units of heredity found inall cells. DNA contains instructions that tell the cells what to do.

The scientists work in a laboratory that has lots of special equip-ment. In a laboratory, a “bench” isn't something you sit on. It’s acountertop where scientists do much of their work. They use equipmentthat includes a centrifuge, rotator, incubators, pipettors and computers.The centrifuge spins particles at very high speeds, separating out heavymaterial and leaving it at the bottom and spinning lighter material tothe top. A rotator mixes up cells. Incubators work like ovens and scien-tists can set them at a certain temperature to grow organisms in a warmplace. Scientists use pipettors the way cooksuse measuring spoons and measuring cups, except that pipettors aredelicate instruments that measure very precise amounts of solutions. Sci-

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Judy collecting

parasites from sharks.

entists use computers to analyze results of their experiments and to helpthem predict what certain substances like DNA and the proteins theywant to isolate might look like.

Judy studies two different kinds of parasites. One is the Anisakisworm. The life cycle of Anisakis takes place in different hosts. The adultworms live in the stomachs of marine mammals such as dolphins andsea lions. The female worms lay eggs which the marine mammals ex-crete with their feces into the ocean. Very young worms called larvaehatch out of the eggs and are eaten by shrimp. The infected shrimp arethen eaten by fish or squid, which in turn are eaten by marine mam-mals. By now the parasite has matured to become an adult and the adultfemales lay eggs, so the Anisakis life cycle starts all over again.

Humans are not natural hosts of this parasite and the worm cannot complete itslife cycle inside a human. But people can become infected with the young worm by eat-ing lightly smoked salmon or raw fish dishes such as sashimi or sushi that are in-fected with Anisakis. The parasites attach to the lining of the human stomach or in-

Life cycle of the Anisakis worm: a. Eggs from adult Anisakis worms leave the

bodies of marine mammals in their feces. b. Anisakis larva hatch from the eggs and

c. are eaten by tiny crustaceans like krill. d. Squid and fish become infected when

they eat the infected krill. e. People are “accidental hosts” when they become infected

by eating raw or improperly prepared seafood. f. When ocean mammals eat infected

squid or fish the cycle is completed.

b

c

d

e

f

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a

testine, or sometimes move from one part of a person’s body to another part. Judywants to find out how they are able to move around in a person’s body. They can makepeople very sick, causing severe pain in the stomach or abdomen, nausea, vomitingand diarrhea. Part of Judy’s job is to teach medical students how parasites infect hu-mans so that when the students become doctors, they will know how to treat patientswho have parasites. She also gives talks to cooks and chefs about safe preparation ofraw fish dishes.

Despite knowing that fish can have parasites inside, Judy continuesto eat raw fish, but she does so very carefully. When she eats a raw fishdish in a restaurant, she examines it closely, looking for thin, flesh-

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colored worms. At home, she freezes raw fish for a few days to kill anyworms that might be in the fish before eating it.

In her role as a research scientist, Judy thinks that if she can findout how the worms can move through a person's body, she may be ableto stop them. She thinks she may find the answer by studying enzymesthat are released by the parasite. Enzymes create chemical changes inother substances, causing them to break down. For example, pepsin isan enzyme in the human stomach that helps digest food by breaking itdown. Judy thinks the parasites “spit out enzymes” that actually digesthuman tissue so that the parasites literally burrow their way from onepart of the body to another.

To conduct her research, Judy has to have parasites to work with. She has builtup a good relationship with distributors at the San Francisco Fisherman’s Wharf whogive out the daily fish catches to restaurants. She shows the distributors what to lookfor in the fish they sell, and she visits the wharf regularly to get specimens for her re-search. Judy goes back to the lab with her “catch” of fish carcasses, cuts out the in-sides and puts them in a beaker with an enzyme that is naturally found in the humanstomach. The enzyme eats away all the fish tissue. The next morning all that’s left areAnisakis worms wiggling around — the worms that were inside the fish.

Why doesn’t the enzyme digest the worms, too?“That’s the $64,000 question,” Judy said. The scientists in her lab

think that the parasite releases substances that prevent the host’s en-zymes from breaking down the parasite. “These substances are called in-hibitors,” Judy said. “The parasite’s inhibitors perhaps prevent the ani-mal’s enzymes from digesting the worm.”

Judy’s lab is studying the inhibitors to try to understand how theywork. If the scientists can learn exactly how the parasite avoids being di-gested, they could then try to design a drug that would prevent the in-hibitor from working. So they extract protein, DNA and other materialfrom the worms to study the biochemistry and molecular biology ofthese persevering parasites.

The other parasite Judy studies is not a worm, but a very tiny one-celled organism called a Protozoa. It’s name is Leishmania (pro-nounced leesh-man-ea.) This tiny parasite is transmitted from host to

Judy and her husband Mike in their garden.11

host by sand flies. If a sand fly bites a person, the parasite can get insidethe person’s skin and form a small sore. The parasite multiplies insidehuman cells and can get into the liver and spleen, making the personvery sick and even causing death. Judy says about 12 million people inthe world are infected with Leishmania. Many drugs used to kill thisparasite are very toxic to humans. Judy studies Leishmania to try to de-velop a better drug for people to take to get rid of this parasite. Shewants to find out if she can eliminate an enzyme the parasite needs forits nourishment. Without that enzyme, the parasite would die.

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When Judy isn’t busy working as a scientist, she and her husband,Mike, enjoy jogging, hiking and working in their vegetable and flowergardens. They live in a house 12 miles north of San Francisco. But beingtogether wasn’t always easy. It can be very difficult for two scientists whoare married to find jobs in the same location. Mike was doing researchat the University of California at Santa Cruz while Judy was in San Fran-cisco doing her postdoctoral work. For six years they lived in separatecities, getting together only on most weekends. But then Mike took anadministrative job at the University of California at Berkeley, and doeshis research during the summer, which allows Judy and Mike to live to-gether.

Although they have encountered some difficulties, there are also veryrewarding aspects of having a spouse who is a scientist, Judy says. Theycan talk to each other about their work. They share a number of friendswho are colleagues. And they get to travel together to many interestingplaces like the Philippines, Brazil, Scotland, England, Switzerland,France and Hawaii to do research and attend professional meetings.They often combine business in other countries with their vacations.Both do a lot of volunteer professional work. Judy helps organize profes-sional meetings, critiques grant applications made by other scientistsand spends time training young scientists.

Mike says what he likes most about his wife is her ability to be botha dedicated scientist and a caring person. Judy is “really disciplined toher work and I think when she makes up her mind to do something,she’s going to work very very hard to do that, and it’s the single-mindedness that will accomplish the goal,” he said. “At the same time,”he added, turning toward his wife over dinner, “you shift gears to bemore humane, to be a gentle person. There’s the shop and the home.”

Judy believes girls should grow up understanding they can find thatbalance as women. “I think it is important for young girls to believe thatthey can have a career as a scientist, be a loving spouse, and have a fam-ily if they so choose,” she said. “It’s not always easy, but I was raised tobelieve that ‘If there’s a will, there’s a way.’ No matter what careerchoice a girl desires, it is important for her to really enjoy the kind ofwork she does and be proud of the person she is.”

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GlossaryAcid - A substance that reacts with a base or alkali to form salt, andturns blue litmus paper red. Common acids are lemon juice andhydrochloric acid.

Alkali - A substance, also called a base, that dissolves in water andneutralizes acids by forming salts with them. It turns red litmus paperblue. Examples are baking soda and ammonia.Bacteria - One-celled organisms so tiny they can only be seen under amicroscope. Some cause diseases and others are useful in processes thatrequire substances to change. For example, some bacteria help cowsdigest grass and other bacteria are used to make yogurt.

Biochemistry - The science that deals with the chemistry of livingmatter.

Biologist - A scientist who specializes in biology, the science of plantand animal life.

Cell - The smallest unit of structure and function in all living things —plants, fish, animals, and humans.

Centrifuge - A machine that separates lighter matter from heavier ordenser matter by means of a rapid spinning motion called centrifugalforce.

Chemistry - The science that deals with the structure of matter and thereactions that occur when elements combine to form new substances.

Colleagues - People working in the same profession.

Debris - Bits and pieces of something that has been destroyed.

Diplomatically - Handled with tact and politeness.

Distributor - Someone who sends out goods to customers.

Diversity - Variety; the presence of many different types of living ornon-living things.

Enzyme - A protein substance produced in cells that acts to stimulate chemicalreaction without being changed itself. For example, enzymes are present in the mouth,stomach and intestines of humans to digest food.

Gills - Feathery structures in a fish with which it breathes under water.Through its gills, a fish brings oxygen into its blood and eliminatescarbon dioxide.

Inhibitor - A substance which prevents or keeps a process fromoccuring. For example, an inhibitor prevents an enzyme from beingactive.

Laboratory Bench - Countertop in a lab where a scientist doesresearch.

Larva - An early, immature stage of some animals which must undergomajor change or metamorphosis to become an adult.

Life Cycle - All the stages of development a living thing passes throughfrom birth to death.

Marine Mammals - Warm-blooded animals with backbones, such aswhales and sea lions, who live in the ocean. Females produce milk tofeed their offspring.

Microscope Lens - A curved piece of glass that makes things appearmuch larger than they are.

Molecular Biology - Study of the smallest particles of living things.

Neutralize - In chemistry, an acid and a base cancel each other’seffects and create a salt.

Parasite - An organism that lives on or in another living thing calledthe host. The parasite gets its food from the host and often harms it.

Pathology - The study of the causes and nature of diseases.

Penetrate - Pierce; get through or inside of something.

Physiology - The branch of biology that studies normal functions ofplants and animals.

Pollution - Any dirty or harmful things, particularly waste products, inthe environment.

Specimen - A sample of a substance or an example of a group, that isusually used for testing.

Wharf - A dock at the edge of a body of water where boats and shipscan load and unload.