Originally posted on WormAtlas by “Rani”, on January 19, 2006
Hello
I apologises for being slightly off-topic, but I’d just like to ask if anyone knows the lengths of both thick and thin filaments in the bodywall-muscle during the various developmental stages of the worm? Do the diameters change? I’d also be interested to learn about different methods for measuring the filament lengths; I’ve been looking in the literature but so far I’ve only managed to find one paper so far (MacKenzie and Epstein, 1980, Cell 22:747-755). Any help would be great.
Rani
Originally posted on WormAtlas by “hall”, on January 23, 2006
Your question might be answered most easily by using polarized light to view animals by light microscopy. I do not know exactly what you will find regarding any changes in filament length. But if you compare the relative distances between dense bodies along the length of the body, within one muscle cell (so being careful to follow exactly along the axis of a filament) you ought to be able to measure whether sarcomere length (and by analogy, filament length) varies or stays the same from larval stages to adult. By looking for the boundaries of M-lines vs dense bodies, etc., with polarized light, you may also get an exact measure of either actin length or myosin length.
You further asked if filaments might change in their cross-sectional dimensions over time. This could perhaps be measured best from thin sections of muscles. I have not tried the measurements, but my expectation is that actin fibrils and myosin fibrils do not change molecular constituents over time and ought to show essentially the same cross-sectional diameters.
David Hall