dictyNews

Electronic Edition

Volume 46, number 25

September 11, 2020



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Abstracts

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Interplay of mesoscale physics and agent-like behaviors in the 

parallel 

evolution of aggregative multicellularity  



Juan A. Arias Del Angel,† Vidyanand Nanjundiah, Mariana Benítez, 

and Stuart A. Newman* 

 

†d. 2019  

*Corresponding author ([log in to unmask] (MB); 

[log in to unmask] (VN); [log in to unmask] (SAN))  





Evolution and Development, accepted  



Myxobacteria and dictyostelids are prokaryotic and eukaryotic 

multicellular lineages, respectively, that after nutrient depletion 

aggregate and develop into structures called fruiting bodies. The 

developmental processes and the resulting morphological 

outcomes resemble one another to a remarkable extent despite 

their independent origins, the evolutionary distance between them 

and the lack of traceable homology in molecular mechanisms. We 

hypothesize that the morphological parallelism between the two 

lineages arises as the consequence of the interplay within 

multicellular aggregates between generic processes, physical and 

physicochemical processes operating similarly in living and non-

living matter at the mesoscale (~10-3 to 10-1 m) and agent-like 

behaviors, unique to living systems and characteristic of the 

constituent cells, defined as autonomous entities acting according 

to internal rules in a shared environment. Here we analyze the 

contributions of generic and agent-like determinants in myxobacteria 

and dictyostelid development and their roles in the generation of 

their common traits. Consequent to aggregation, collective cell-cell 

contacts mediate the emergence of liquid-like properties, making 

nascent multicellular masses subject to novel patterning and 

morphogenetic processes. In both lineages, this leads to behaviors 

such as streaming, rippling, and rounding up, as seen in non-living 

fluids. Later the aggregates solidify, leading them to exhibit additional 

generic properties and motifs. Computational models suggest that 

the morphological phenotypes of the multicellular masses deviate 

from the predictions of generic physics due to the contribution of 

agent-like behaviors of cells such as directed migration, quiescence, 

and oscillatory signal transduction mediated by responses to 

external cues. These employ signaling mechanisms that reflect the 

evolutionary histories of the respective organisms. We propose 

that the similar developmental trajectories of myxobacteria and 

dictyostelids are due to shared generic physical processes in 

coordination with analogous agent-type behaviors rather than to 

convergent evolution under parallel selection regimes. Insights from 

the biology of these aggregative forms may enable a unified 

understanding of developmental evolution, including that of 

animals and plants.





submitted by: Vidya Nanjundiah [[log in to unmask]]

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[End dictyNews, volume 46, number 25]