The cellular slime mold Dictyostelium discoideum is a eukaryote that lives on the forest floor as
independent motile cells. When their food supply is exhausted, the amoeba, stop dividing and gather
together to form tiny, multicellular worm like structures, which crawl about as glistening slugs and leave
trails of slime behind them. How do individual amoebae know when to stop dividing and how to find their way into a common aggregate?
It was shown that amoebae aggregate if placed on a glass coverslip under water, provided that simple salts are present. The center of aggregation pattern can be removed with a pipette and placed in a field of fresh amoebae, which immediately start streaming toward it. What does this imply?
Four experiments were designed to determine the nature of the signal by using an existing center of
aggregation as the source of the signal and previously unexposed amoebae as the target cells. The
arrangements of aggregation centers are shown in the figure * below.
What do the results show?
a) Individual amoebae know when to stop dividing by emitting chemical signals, these signals tells the amoebae when to stop dividing.
b) Amoeba starts streaming towards the aggregate because the aggregate emitted alluring signals.
c) The results show that;
In all the cases that there is an already aggregating amoeba and there is fresh non-aggregated Dictyostelium discoideum, it's also observed that there are secreted chemicals that signal the fresh amoeba aggregation.