Monday, December 17, 2018
Fastest? Hardly.
This article adds more knowledge of a super-simple critter. Trichoplax is in the running for simplest multi-celled animal, depending on how you define multi-celled.
Headline: Fastest-Ever Cell Contractions Observed in Primitive Invertebrate
Fastest?
The adult marine invertebrate Trichoplax adhaerens, a critter in the shape of a smashed wad of chewing gum no bigger than a piece of lint, consistently contracts and relaxes the cells on the top of its body at speeds nearly 10 times faster than ever before observed in an animal. When they recently used a fluorescent dye to visualize the cell membranes, they saw that cells in the top layer of epithelium contracted their surfaces more than 50 percent over the span of a single second—an observation that Prakash describes as “a huge surprise.”Faster than prestin? Prestin is found in the cell walls of the outer hair cells of cochleas, and helps to emphasize or cancel parts of the sound, under high-level control. If a frequency is deemed more important, the hair cells move with it; if a frequency is unwanted, the hair cells counter it. Here's how fast prestin moves:
Unlike the classical, enzymatically driven motors, this new type of motor is based on direct voltage-to-displacement conversion and acts several orders of magnitude faster than other cellular motor proteins. ... Stimulated at their basal end, cells from the apical (low‐frequency) cochlear turns responded with a latency of between 120 and 255 microseconds.A half-cycle of 120 microseconds implies a vibration of 4000 cps. Even ordinary muscles contract much faster than 1 second. Without trying you can vibrate your hand at 10 cps. Pianists and athletes can do much better. Maybe the trichoplax researchers are talking about the amount of contraction of one cell, down to 50% of its length in one second? Again, lots of ordinary muscles match or beat that number. Well then, what are they talking about? ¶ 2:59 PM
