Scialog: Collaborative Teams - 2015
Physics, University of Massachusetts
Michael J. Rust
Molecular Genetics, University of Chicago
Building an Artificial Motile Tissue through Self-Organized Rhythmic Contractility
Three scientists have come together in an attempt to build a biologically based artificial tissue that moves under its own power. “We’re doing this to gain insights into how molecular-level interactions, chemical oscillators, and filament mechanics combine to cause large-scale motions,” they noted in their research proposal.
The three scientists are Rae Robertson-Anderson, associate professor of physics and biophysics, University of San Diego; Jennifer Ross, associate professor of physics, University of Massachusetts, Amherst; and Michael J. Rust, assistant professor of molecular genetics and cell biology, University of Chicago.
Robertson-Anderson, Ross, and Rust hope to create the moving artificial tissue in a way not unlike a master mechanic builds a functioning car from various stray parts.
The plan calls for salvaging a 24-hour circadian oscillator system from cyanobacteria, a type of bacteria, such as blue-green algae, that obtain their energy through photosynthesis. In basic terms, the oscillator system is composed of several proteins that undergo a process called phosphorylation, meaning the presence or absence of a phosphate molecule turns them on or off. Remarkably, this protein oscillator can keep running even outside of a living cell, making it a powerful tool for building synthetic systems. The researchers will use the oscillator to produce a rhythmic contraction of actomyosin, a complex of proteins forming contractile muscle tissue.
In addition they hope to create a gel that can be activated to compress or buckle. They plan to create the gel primarily from two important macromolecules found in the cytoskeleton of cells: semiflexible actin filaments, responsible for muscle function, and hollow rigid microtubules rods, that form the “bones” of a cell.
Then they plan on using the oscillator system to transmit synchronized contractions across the gel.
Finally, they hope to combine the oscillators, the gel and the enzyme adenosine triphosphate (ATP), a molecule that stores energy for living cells, to create a “complete oscillating contractile material.” The plan is to study this material with advanced techniques under various laboratory-imposed conditions. The goal is to determine precisely how and with what amount of force actin filaments “slide” to produce muscle contractions, as well as to observe the effects of gel composition, mechanical response, viscosity, and other factors on this process.