| Comments |
P.2 right column 3rd paragraph: "The number rate of precursor consumption necessary for growth, S, is determined by the area growth rate of fibrils: S=(dA/dt)/σ (4) where dA/dt is the net growth of fibril area for all fibrils in a bundle following fibril formation, and σ is the area per precursor. The cross-sectional diameter of one collagen molecule is approximately 1.08 nm [BNID 112905], so that σ=0.916 nm^2. From figure 1, after birth (at t = 20 d) the number of fibrils per bundle is approximately fixed and so growth of total fibril area in a bundle is due to the increasing size of individual fibrils. [Investigators] approximate the growth of the total fibril area as linear in time, with dA/dt≈0.37 μm^2/day as indicated by the dashed line in figure 1(a). Linear growth provides a (conservative) lower bound on the maximal growth rate and hence on S. This fibril area growth rate gives S≈4.7/s, as the number of fully processed collagen molecules needed per second to support growth of each individual bundle." |