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bioRxiv · 10.1101/2023.03.27.533254

Cooperative Motility, Force Generation and Mechanosensing in a Foraging Non-Photosynthetic Diatom

Zheng, P.·Kumadaki, K.·Quek, C.·Lim, Z. H.·Ashenafi, Y.·Yip, Z. T.·Newby, J.·Alverson, A. J.·Jedd, G.
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Abstract

Diatoms are ancestrally photosynthetic microalgae. However, some underwent a major evolutionary transition, losing photosynthesis to become obligate heterotrophs. The molecular and physiological basis for this transition is unclear. Here, we isolate and characterize new strains of non-photosynthetic diatoms from the coastal waters of Singapore. These diatoms occupy diverse ecological niches and display glucose-mediated catabolite repression, a classical feature of bacterial and fungal heterotrophs. Live-cell imaging reveals deposition of secreted extracellular polymeric substance (EPS). Diatoms moving on pre-existing EPS trails (runners) move faster than those laying new trails (blazers). This leads to cell-to-cell coupling where runners can push blazers to make them move faster. Calibrated micropipettes measure substantial single cell pushing forces, which are consistent with high-order myosin motor cooperativity. Collisions that impede forward motion induce reversal, revealing navigation-related force sensing. Together, these data identify aspects of metabolism and motility that are likely to promote and underpin diatom heterotrophy.

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Zheng, P., Kumadaki, K., Quek, C., Lim, Z. H., Ashenafi, Y., Yip, Z. T., Newby, J., Alverson, A. J., Jedd, G.. 2023-03-27. Cooperative Motility, Force Generation and Mechanosensing in a Foraging Non-Photosynthetic Diatom. https://doi.org/10.1101/2023.03.27.533254

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