Video credit and details, from the Nikon Small World in Motion video competition, via Neatorama.
Lots of fascinating brief science videos at that second link*. This cytoplasmic streaming fascinates me. Can some reader explain what directs this motion? Are there cilia on the tubule walls?
*if/when you visit, check out the "soy sauce evaporating."
"This cytoplasmic streaming fascinates me. Can some reader explain what directs this motion? Are there cilia on the tubule walls?"
ReplyDeleteTHis is a reallly interesting question, and since I'm not a professional in the field I will defer to them from my fragmented understanding. What you're seeing is not cilia waving from one spot to push the fluid along, but that there are filaments being moved along the walls of the tube that are attached to chloroplasts and other elements. As these objects are moved along the tube, they "entrain" the fluid, pulling/ pushing it along. A way to think about it, is imagine you are were driving cars down a ditch full of water. The cars would push/ pull the water in the channel along with them producing a flow of water.
More technically, myosin filaments connect cell organelles to actin filaments. These actin filaments are generally attached to the chloroplasts and/or membranes of plant cells. The myosin molecules "walk" along the actin filaments dragging the organelles with them. This motion of dragging the organelles along through the fluid, causes the cytoplasmic fluid to become entrained and is pushed/pulled along.
Interesting that it is so well coordinated at the intracellular level that the flow becomes almost laminar rather than chaotic. That would imply that there is some ?neurologic communication between the myosin and actin filaments.
DeleteContributing, and possibly making it possible by increasing flow an decreasing resistance, actin is a polar molecule. This means that the myosin can only go one direction relative to the actin. It is fascinating to see and only happens when light is present (I think).
ReplyDeleteIt happens more/faster in the light.
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