Amazing stuff!
"... F. alba, which has only ever been found in the environment one time (on some dog feces from Arkansas, back in the 1960s), drew little interest until a few years ago, when scientists from the University of Geneva became interested in its unique position on the evolutionary tree. While most previously characterized slime molds, such as Dictyostelium spp., are relatives of animals and plants, F. alba is instead more closely related to fungi than other slime molds.
“Fungi and animals are very closely related on the evolutionary tree,”...
“Fungi and animals are very closely related on the evolutionary tree,”...
Like most slime molds, it spends most of its life in a single-cell form, as an amoeba feeding on bacteria. At some point in its life cycle, however, it becomes multicellular, joining with others into volcanolike fruiting bodies, which release spores and help the slime mold propagate. ...
F. alba’s other multicellular behavior: invasion. ... that F. alba only entered its aggregative state when cocultured with bacteria—in this case, the common fecal bacteria Klebsiella pneumonia—that’s in a particular phase of the bacterial life cycle. ... It was exposure to bacteria in the scarcity-driven sunset phase that prompted the slime mold to aggregate ...
The researchers found that in its invasive social state, F. alba sweeps through the depleting bacterial lawn, feasting and searching for new food sources as it goes. The researchers compared this invasive mechanism to how cancer cells collectively burrow into surrounding tissues and fungi’s use of long, branching filaments to creep along, searching for new sources of food, though the mechanisms by which F. alba invade bacterial colonies remain unknown. The slime mold cells form multicellular tendrils that extend through bacteria-filled agar, in which “follower cells” are guided by a single “leader” cell. In this state, the cells in the tendril communicate—when a leader cell enters a bacteria-free environment, it signals the cells following it to turn around. Cancer cells also use a coordinated, leader-follower configuration to migrate into adjacent tissues from the primary tumor. ..."From the abstract:
"Multicellularity evolved in fungi and animals, or the opisthokonts, from their common amoeboflagellate ancestor but resulted in strikingly distinct cellular organizations. The origins of this multicellularity divergence are not known. The stark mechanistic differences that underlie the two groups and the lack of information about ancestral cellular organizations limits progress in this field. We discovered a new type of invasive multicellular behavior in Fonticula alba, a unique species in the opisthokont tree, which has a simple, bacteria-feeding sorocarpic amoeba lifestyle. This invasive multicellularity follows germination dependent on the bacterial culture state, after which amoebae coalesce to form dynamic collectives that invade virgin bacterial resources. This bacteria-dependent social behavior emerges from amoeba density and allows for rapid and directed invasion. The motile collectives have animal-like properties but also hyphal-like search and invasive behavior. These surprising findings enrich the diverse multicellularities present within the opisthokont lineage and offer a new perspective on fungal origins."
The cellular slime mold Fonticula alba forms a dynamic, multicellular collective while feeding on bacteria (open access)
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