Plant Biology

One-celled algae provide food for fish and food for thought

In a pond, one-celled algae known as Chlamydomonas provide food for fish, waterbugs, and other creatures. In Carolyn Silflow's lab, the microscopic green creatures are providing food for thought as Silflow works to understand a type of subcellular structure that not only helps Chlamydomonas move, but also plays a part in a spectrum of biological functions, from reproduction in primitive plants to hearing in humans.

Carolyn Silflow and Paul Lefebvre conduct genetic research on Chlamydomonas, a one-celled algae, that is providing insights into a variety of human ailments.

A professor of plant biology, Silflow studies Chlamydomonas' flagella, two whiplike appendages that beat in a breast-stroke pattern to propel it through its watery world. In particular, she's got her eye on the root of the matter'subcellular structures called basal bodies from which flagella arise. By learning the role various genes play in the construction and function of basal bodies, Silflow hopes to shed light on how flagella and their close relatives, cilia, work' and why they don't when they don't.

To learn about basal bodies, Silflow is using a process called gene discovery. First, she creates mutations that affect the number, position, and movement of flagella. She then looks at the genetic material of the mutants to find out which gene has been altered. Once she knows the gene, she can identify the corresponding protein. Finally, she can figure out the protein's function based on what she knows about what's awry with the mutant. So far she's made seven kinds of mutants and has identified the genes and proteins associated with four of them.

The biochemical pathways Silflow is exploring as she works to learn how flagella work are fascinating for their own sake. But her research is drawing attention for other reasons, too. It turns out an amazing array of structures in people and other animals'tails of sperm, the ciliated cells that clear airways, light-sensing structures in eyes, sound-sensing cells in inner ears, cells that usher eggs from ovary to fallopian tube, kidney cells that help cleanse blood'all contain structures remarkably similar to flagella. As a result, information on how Chlamydomonas flagella work is providing valuable insights into a spectrum of human ailments, including some forms of infertility, vision problems, and kidney disorders.

'My motivation is not working on a particular disease; I get a lot of satisfaction just from the very basic work of trying to understand the molecular mechanisms,' Silflow says. 'But because these are highly conserved organelles I know that what I learn is important in the bigger picture.'

In addition to looking at specific mutations, Silflow has been working with Paul Lefebvre, another professor of plant biology who is using gene discovery to explore flagellar mutations, to create a molecular map of the Chlamydomonas genome. The map will improve researchers' ability to use gene discovery to identify and characterize genes that control various aspects of Chlamydomonas structure and function.

'It allows you to go from a phenotype to then clone the gene that is mutated to give you that phenotype,' Silflow says. 'So if you map the mutation genetically you can go into that region of the genome and clone the gene.'

'Mary K. Hoff