Slime Molds

Full skill ahead. Online video courses from $9.99

Related Posts


 Illustration shows the plasmodium slime mold life cycle, which begins when 1n spores germinate, giving rise to cells that can convert between amoeboid and flagellated forms. Fertilization of either cell type results in a 2n zygote. The zygote undergoes mitosis without cytokinesis, resulting in a single-celled, multinucleate mass visible to the naked eye. A photo inset shows that the plasmodium is bright yellow and looks like vomit. As the plasmodium matures, holes form in the center of the mass. Stalks with bulb-shaped sporangia at the top grow up from the mass. Spores are released when the sporangia burst open, completing the cycle.
Plasmodial slime molds. The life cycle of the plasmodial slime mold is shown. The brightly colored plasmodium in the inset photo is a single-celled, multinucleate mass. (credit: modification of work by Dr. Jonatha Gott and the Center for RNA Molecular Biology, Case Western Reserve University)

OpenStax Biology 2e

A subset of the amoebozoans, the slime molds, has several morphological similarities to fungi that are thought to be the result of convergent evolution. For instance, during times of stress, some slime molds develop into spore-generating fruiting bodies, much like fungi.

The slime molds are categorized on the basis of their life cycles into plasmodial or cellular types. Plasmodial slime molds are composed of large, multinucleate cells and move along surfaces like an amorphous blob of slime during their feeding stage. Food particles are lifted and engulfed into the slime mold as it glides along. The “dog vomit” slime mold seen in the image above is a particularly colorful specimen and its ability to creep about might well trigger suspicion of alien invasion. Upon maturation, the plasmodium takes on a net-like appearance with the ability to form fruiting bodies, or sporangia, during times of stress. Haploid spores are produced by meiosis within the sporangia, and spores can be disseminated through the air or water to potentially land in more favorable environments. If this occurs, the spores germinate to form ameboid or flagellate haploid cells that can combine with each other and produce a diploid zygotic slime mold to complete the life cycle.

The cellular slime molds function as independent amoeboid cells when nutrients are abundant. When food is depleted, cellular slime molds aggregate into a mass of cells that behaves as a single unit, called a slug. Some cells in the slug contribute to a 2–3-millimeter stalk, drying up and dying in the process. Cells atop the stalk form an asexual fruiting body that contains haploid spores. As with plasmodial slime molds, the spores are disseminated and can germinate if they land in a moist environment. One representative genus of the cellular slime molds is Dictyostelium, which commonly exists in the damp soil of forests.

The image shows several stages in the life cycle of Dictyostelium discoideum. It appears as fibers or very thin stalks topped with circular structures
Cellular Slime Mold. The image shows several stages in the life cycle of Dictyostelium discoideum, including aggregated cells, mobile slugs and their transformation into fruiting bodies with a cluster of spores supported by a stalk. (credit: By Usman Bashir (Own work) [CC BY-SA 4.0 (http://creativecommons.org/licenses/by-sa/4.0)], via Wikimedia Commons)

Source:

Clark, M., Douglas, M., Choi, J. Biology 2e. Houston, Texas: OpenStax. Access for free at: https://openstax.org/details/books/biology-2e


Advertisements
Advertisements


0 0 vote
Article Rating
Subscribe
Notify of
guest
0 Comments
Inline Feedbacks
View all comments