Condensed Matter Seminar: "Clogging and anti-clogging in biological networks"

Wed, 10/21/2015 - 16:00 - 18:00
Marcus Roper (UCLA)

Clogging, or congestion, is usually assumed to be the enemy of efficient transport, and a lot of energy is expended by human engineers to eliminate or tame clogging in transport networks -- whether they carry fluid, data or cars. In this talk I will describe two examples of biological transport networks, in which the potential for clogging exists. In the first example, flow regulation completely eliminates clogging. In the second clogging is intentfully triggered, suggesting that Nature's attitude to clogging may be more nuanced than we previously realized.

1) In filamentous fungi, continuous flow of cytoplasm and nuclei is needed to maintain growth at the edge of the fungal network. Organelles transported by these flows self-organize into anti-jams that sweep through the network. Anti-jams form because the flow is anti-clogging: that is, the more densely packed nuclei are on a hyphal highway, the faster they flow. Regular cycling of the cellular interior between phases of transport and quiescence during and after the passage of an anti-jam allows hyphal highways to switch temporally between functioning as transport conduits and performing other functions like growth and remodeling.

2) In arterial networks gas exchange occurs over billions of capillaries occur throughout the body at very different distances from the heart. Why don't the the vessels that are closest to the heart short circuit the network? Using the zebrafish embryo as a physical model, we show that controlled clogging of red blood cells within peripheral vessels make flows uniform between the smallest vessels. In addition to revealing a surprising design principle of peripheral vessels, the tradeoffs created between efficient flow and uniform flow suggest that vascular networks may prioritize uniformity over efficiency.

David Rittenhouse Laboratory, A4