Living Laboratories: How Model Organisms Advance Science

Edited by Stephanie Dutchen, National Institutes of Health

Date: 01 June 2011 Time: 09:26 AM ET

How does genetic inheritance occur? How do cells grow and divide? How do our brains work? What drives eating, sleeping, aggression and other human behaviors?

Because the basic operating principles are nearly the same in all living things, studies involving model organisms — microbes, fungi, plants and animals — can teach us about biological processes in people and give us insight into these fundamental questions. From amoebas to zebrafish, research using model organisms — much of it funded by the National Institutes of Health — continues to lead to new ways to maintain health and diagnose and treat disease.

Below, meet five of science's most popular model organisms.

1. E. coli (Bacterium)

E. coli is notorious for its link to tainted beef and other foods. But for scientists, E. coli is a key model organism that has helped uncover many of the cell's fundamental processes. Scientists have sequenced E. coli genomes to understand genetic differences between beneficial and harmful bacteria. Other studies focus on metabolism and gene expression, potentially uncovering new ways to treat bacterial infections and human disease.

"Once we understand the biology of Escherichia coli, we will understand the biology of an elephant," said Jacques Monod, a French Nobel laureate. Here, a map of surface proteins helps researchers better understand protein organization and cell signaling.
CREDIT: Derek Greenfield and Ann McEvoy, University of California, Berkeley.

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2. Dictyostelium discoideum (Slime Mold)

Though we may not appear to have much in common with a slime mold, scientists have discovered that many of its genes are close copies of our own. Because of its unusual properties and ability to live alone or in a group, the slime mold intrigues researchers who study cell division, movement and various aspects of organ and tissue development.

The fruit of Dictyostelium discoideum. A group of 100,000 are about the size of a grain of sand.
CREDIT: Rex Chisholm, Northwestern University.

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3. Neurospora crassa (Bread Mold)

There's a reason people joke about using moldy bread as a science experiment. Thousands of researchers study the common mold Neurospora to answer questions about how species arise and adapt as well as how cells and tissues change their shape in different environments. Since Neurospora produces spores on a 24-hour cycle, it's also useful for understanding biological clocks.

The bread mold Neurospora crassa has been a historically important model organism.
CREDIT: Namboori B. Raju, Stanford University.

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4. Saccharomyces cerevisiae (Yeast)

The same yeast used by bakers and brewers has been an indispensable tool for scientists. A fungus (not a plant, not an animal, but related to both) and a eukaryote (a "higher" organism with an organized, protective nucleus that holds its chromosomes), yeast has endeared itself to researchers in part because it grows fast and its genes are easy to work with. Because of that ease, experiments with yeast have taught us about how mammalian genes work and what happens when they don't work, clarified how genes are turned on or off and explained how cells that contain the same genes can be so different from one another. Yeast studies also helped scientists sort out the orderly sequence of events in which a cell divides. That information has benefited millions of people, since many cancer drugs interfere with the same cell cycle.

This snapshot, taken with X-ray microscopy, displays the inside of a rapidly frozen whole yeast cell as it buds before dividing in two. Seeing the parts of a cell captured in action helps scientists study complex structures and how molecules move inside them.
CREDIT: Carolyn Larabell, University of California, San Francisco, and the Lawrence Berkeley National Laboratory.

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5. Arabidopsis thaliana (Mustard Plant)

A small flowering plant related to cabbage and mustard, Arabidopsis — the most popular model for studying plant genetics — is appealing to biologists because ithas almost all of the same genes as other flowering plants and has relatively little DNA that doesn't encode for proteins. It also grows quickly, going from seed to mature plant in only 6 weeks. Because plant cells and cell parts communicate with each other in much the same way that human cells do, Arabidopsis and other plants make good models for genetic diseases that affect cell communication, such as cystic fibrosis, Huntington's disease and Fragile X syndrome.

This Arabidopsis embryo begins to polarize so its top half will form a shoot and the bottom half will send out roots. Any error in the carefully orchestrated plan can lead to major defects in the plant. Because humans and animals have similar gene networks that coordinate development, studying such polarity could help us better understand human development.
CREDIT: Zachery R. Smith, Jeff Long lab at the Salk Institute for Biological Studies.

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This Inside Life Science article was provided to LiveScience in cooperation with the National Institute of General Medical Sciences, part of the National Institutes of Health.