From birth defects to heart disease, small fish vital to understanding disease origins
Read the Video on Zebrafish text alternative.
As they strive to develop new treatments for birth defects, or to prevent them, scientists at the National Institutes of Health have found a big ally in a small fish.
An NIH video shows how the zebrafish, Danio rerio, is a valuable resource for scientists trying to understand the intricate process by which a fertilized egg develops into a fully formed individual, and the numerous diseases and conditions that can result when even a tiny part of the process goes wrong.
"Our institute supports research to ensure that human beings get the best start possible, so all people have the chance to reach their potential, regardless of disease or disability," said Alan E. Guttmacher, M.D., Director of the NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). "Many disorders and conditions arise early in embryonic life, when we can't directly observe them in humans. For this reason, we rely on animal models to stand in for humans to provide insight into the developmental process."
In the new video, "Zebrafish: A Key to Understanding Human Development,'' Dr. Guttmacher describes the role zebrafish play in the study of developmental processes.
Unlike human embryos, which develop in the mother, usually in nine months, Zebrafish eggs are fertilized outside the mother, and the embryos develop in the water, and development is rapid. The eggs and embryos are transparent, and so scientists can observe them under a microscope as they develop.
Because zebrafish have many genes in common with human beings, researchers can extrapolate what they learn from studies of zebrafish to human disorders and conditions. Like human beings, zebrafish are vertebrates—animals with backbones. Other common model organisms, such as the fruit fly, Drosphopila melanogaster, and the nematode worm, Caenorhabditis elegans, do not have backbones, so information from studying these organisms is less applicable to human development than is information from zebrafish studies.
Popular in home aquariums throughout the world, zebrafish are native to south Asia. They reach about 1 ½ inches in length and have alternating horizontal blue and white stripes.
The video includes footage of the NIH zebrafish facility. The facility is the largest in the world, with enough space for 19,000 tanks to accommodate 100,000 fish. Zebrafish females can produce hundreds of eggs in a single mating. Many studies require large numbers of fish, to test different compounds, to test varying doses of a compound, or to allow scientists to search for an uncommon genetic variation.
"Answering the most important questions in science requires a facility of this size," Dr. Guttmacher said.
The facility uses 25,000 gallons of water, only about 40 percent of which circulates through the tanks at any one time. The remainder flows through a high tech filtration system to remove wastes. The water temperature is maintained at 82 degrees Fahrenheit and the water chemistry is rigidly controlled. Before entering the tanks, the water is pumped past ultraviolet light to kill any bacteria or other organisms with the potential to cause disease. Lighting simulates a 24- hour day, with dawn and dusk. The fish are fed a variety of foods, including a dry, prepared mix as well as live brine shrimp.
The facility is operated jointly by the NICHD and the NIH's National Human Genome Research Institute. A number of other NIH institutes also conduct research at the facility, including the National Cancer Institute, the National Heart, Lung and Blood Institute, the National Eye Institute, and the National Institute of Alcohol Abuse and Alcoholism.
In addition, the National Institutes of Health also funds research studies employing zebrafish at a number of research institutions around the country and in other parts of the world, explained Lorette Javois, Ph.D., of NICHD's Developmental Biology, Genetics, and Teratology Branch. Dr. Javois is cochair of The Trans-NIH Zebrafish Initiative , which coordinates funding for research involving zebrafish among the NIH institutes. It also serves as a resource for scientists involved in research with zebrafish.
In the video, NICHD scientist Brant Weinstein, Ph.D., describes his work using zebrafish to study blood vessel development. Dr. Weinstein is the director of the program on Genomics of Differentiation.
"The detail is incredible—we can observe the formation of new blood vessels, down to the level of individual blood cells traveling through a vessel," Dr. Weinstein said.
Studies of blood vessel development in zebrafish may provide information on how to stimulate blood vessel development after a heart attack or on how to block the formation of blood vessels that supply tumors.
The video also includes an interview with Harold Burgess, Ph.D., of the Unit on Behavioral Neurogenetics. Burgess studies the zebrafish startle response—a reflexive swimming motion that 5-day-old zebrafish display when frightened by a sudden noise or vibration. Burgess is identifying brain cells that control this behavior, in hopes of finding clues to the development of the comparable behavior seen in human beings after sudden exposure to a loud noise. Understanding the startle reflex may lead to advances against conditions involving the startle reflex, such as post-traumatic stress disorder and anxiety disorders.
###About the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD): The NICHD sponsors research on development, before and after birth; maternal, child, and family health; reproductive biology and population issues; and medical rehabilitation. For more information, visit the Institute’s website at http://www.nichd.nih.gov/.
About the National Institutes of Health (NIH): NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit http://www.nih.gov.