Science Fair Projects and Laboratory Exercises

Materials for the following experiments are available from the Chlamydomonas Center. Kits designed for high school science fair projects include either cells ready to use in liquid culture or ingredients for making media at home using bottled water, and do not require use of an autoclave or other specialized equipment.

Prices include Federal Express shipping within the U.S.
For shipment to Canada, please add $10 per order.
For other countries, please add $20 per order.
A quarantine permit is required for shipment to Australia, New Zealand, or Hawaii.

We can also supply cultures and stock solutions for the experiments described on the Chlamydomonas Teaching Center page.

To order a kit, please send your complete mailing address, phone number and the day on which you would like to receive the kit to chlamy@duke.edu

For Tuesday delivery, please place your order by the preceding Wednesday. For Friday delivery, your order should be received by Monday morning of the same week.

Hydrogen evolution

Chlamydomonas, like a number of other kinds of algae, has a reversible hydrogenase that can reduce protons to molecular hydrogen. Melis et al. (Plant Physiology 122, 127-135, 2000) have shown that this activity is inducible in photosynthetically growing cells on deprivation of oxygen and sulfur. This process has potential economic importance as a source of hydrogen for fuel, especially if the native hydrogenase can be modified genetically to reduce its sensitivity to oxygen.

    Hydrogen project kit for one student: contains Chlamydomonas cultures in liquid, stock solutions for complete and sulfur-deficient media, copies of the Melis et al. paper and a review paper, plastic tubing and connectors, instructions. You will also need a fluorescent lamp and two 750 ml or 1-liter bottles of commercial spring water, preferably the kind with a pull-up drinking spout. $40

Phototaxis

Chlamydomonas cells perceive light using a primitive "eye". The light receptor is a rhodopsin, similar to the visual pigment in human and animal eyes. A specialized cellular region beneath this light receptor contains a layer of globules containing a carotenoid pigment, the orange "eyespot" depicted in the illustration at the top left corner of this page. The carotenoid layer helps focus the light on the true receptor, the rhodopsin. Movement can be toward or away from a light source, depending on its intensity.

Phototactic accumluation of cells can be demonstrated using just a petri dish partially covered with black electrical tape. A more elaborate apparatus for observation under a microscope, based on a design by Tony Moss, can also be constructed.

These experiments can be extended to include analysis of several mutant strains that are unable to carry out efficient phototaxis because they lack the eyespot structure, are defective in the signal transduction pathway that enables the cells to respond to light, or can't swim normally.

Some strains of Chlamydomonas show a strong circadian rhythm of phototaxis. This can be demonstrated in cells entrained for a week on a light-dark cycle.

    Phototaxis Mutant kit: Cultures of wild-type and mutant strains in liquid for observation by one student over a few days; no preparation of media or subculturing is required. For classroom use, we ship the cultures on agar and provide stock solutions for making the liquid medium. Some background material and references are also included. $40.

    Circadian Rhythm kit: Wild-type strain CC-124 for the circadian rhythm experiment, plus stock solutions for culture medium, and instructions $25

    Combined Phototaxis kit: Combination of #1 and #2, to do the circadian rhythm experiment and to examine phototaxis of mutant strains. $50.

Motility

Many Chlamydomonas mutants with impaired motility have been characterized. Because the structure of the Chlamydomonas flagellum is virtually identical to that of animal cilia, this system is an excellent model for investigation of flagellar and ciliary structure and function. Defects in central pair microtubules, dynein arms, radial spokes, and basal bodies produce characteristic alterations in swimming that are easily observed with a microscope.

    Motility kit: a selection of motility mutants, plus reference materials. $40.

Chlamy Mating and Dikaryon Rescue

For many years the Plant Diversity course at Duke has included a laboratory demonstration of Chlamydomonas mating. Droplets of mating type plus and minus gamete suspensions are mixed on a microscope slide. Pairing and cell fusion occur rapidly, and are followed by a transient stage where the newly formed zygote swims about with four flagella. No equipment is required except microscopes, and it's fun to watch.

The quadriflagellate cell produced by gamete fusion remains motile for about two hours before the flagella are resorbed and formation of the zygospore wall begins. During this motile period, flagellar assembly continues, and polypeptides contributed by both parental gametes are incorporated into all four flagella. Thus mating of two non-allelic paralyzed mutants usually results in restoration of full motility in this transient dikaryon, as each partner supplies a wild-type copy of the defective flagellar protein produced by the other gamete. Watching the restoration of motility makes a good laboratory exercise for an undergraduate biology course.

    Chlamy mating kit: gamete cultures in liquid, including complementing non-motile mutants and wild-type controls for the dikaryon rescue experiment, plus instructions $40. This kit provides enough material for 10 students.

    Note: the major biological supply houses also sell Chlamydomonas mating kits for classroom use. We've been told ours are much more active.

Uniparental Inheritance

Nuclear mutations in Chlamydomonas segregate 2:2 in meiotic tetrads, whereas chloroplast mutations are transmitted only by the mating type plus parent in most zygotes, producing a 4:0 segregation pattern. Some years ago Jacqueline Hoffman at Washington University developed a laboratory exercise using chloroplast antibiotic mutations in both mating types that has proved to be a classic experiment for demonstrating uniparental inheritance in college genetics courses.

    Uniparental Inheritance kit: cultures of antibiotic resistant mutants, detailed instructions, antibiotics, stock solutions for culture media. $100. If you'd prefer to provide your own antibiotics (streptomycin and erythromycin, available from Sigma, hospital pharmacies, or other suppliers), we can ship just the cultures and instructions for $40.

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