Exploring the Mysteries of Slime Molds

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Slime molds are mysterious organisms found in nature under cool, dark, humid conditions. Carolina kits offer high school and college students a unique opportunity to work with 2 common slime molds, Physarum polycephalum and Dictyostelium discoideum.

Physarum is easy to culture and handle and exists in 2 forms: a motile, multinucleate mass of protoplasm and a dry, resistant structure called a sclerotium. Dictyostelium is a cellular slime mold. Unlike Physarum, the cells of Dictyostelium always retain their individuality, even though they aggregate in a mass called a pseudoplasmodium.

With the Introduction to Physarum Kit, students observe cytoplasmic streaming and plasmodial fusion, plus investigate factors influencing plasmodial growth and sclerotia formation. The Chemotaxis in Physarum polycephalum Kit presents methods and procedures that enable students to design and conduct active investigations of slime mold chemotaxis.

Using the Introduction to Dictyostelium and Other Social Amoebae Kit, students explore the slime mold life cycle. Investigations include factors that trigger the development of different life cycle stages, the behavior and biology of the multicellular stages, how different species of cellular slime molds interact, and more.

There are 2 main reasons why Physarum and other slime molds have been popular research organisms for many years. First, they seem unusual to us because they possess characteristics that appear both fungal and protozoan. In 1859, de Bary suggested the name “Mycetozoa” (fungus-animal) to describe these organisms.

Second, as evidenced by their life cycle, slime molds display many of the same important eukaryotic features seen in more complex organisms such as vertebrates. These include cell differentiation, motility, and mitosis. Yet, slime molds can be grown and handled like microorganisms.

Displaying protozoan characteristics, the slime mold life cycle starts with haploid, independently feeding soil amoebae. Under appropriate conditions, amoebae fuse and form an amoeboid zygote, which undergoes mitosis without cell division. This produces a giant, multinucleate, diploid plasmodium.

Plasmodia are motile and crawl in search of food. As plasmodia eat, they continue to grow and can reach enormous sizes—from lab cultures more than 30 cm in diameter to natural specimens more than 100 cm in diameter! Actively avoiding the dark while feeding, plasmodia move toward the light when starved.

Displaying fungal characteristics, the plasmodium under appropriate conditions stops moving and forms fruiting bodies. Each fruiting body possesses thousands of resistant spores. In favorable conditions the spores germinate, each releasing an amoeba, and the life cycle can start again. Slime molds can also form 2 other types of resistant structures: amoebic cysts and plasmodial sclerotia.

Slime molds are mysterious, but with Carolina kits and cultures, high school and college students can develop a thorough understanding of these fascinating organisms. From cytoplasmic streaming and plasmodial fusion to chemotaxis, students can explore the many aspects of the slime mold life cycle. For our complete selection of slime mold kits and cultures, see our Carolina™ Science catalog or visit us online at  Carolina.com.