Satellite cell division and fiber hypertrophy alternate with new fiber formation during indeterminate muscle growth in juvenile lake sturgeon (Acipenser fulvescens)

Canadian Journal of Zoology, e-First Articles. Age-dependent changes in muscle fiber size, myonuclear domain volume, fiber-end-terminal configuration, fiber and fish growth, and stem cell or satellite cell (SC) number and proliferation were investigated in developing lake sturgeon (Acipenser fulvescens Rafinesque, 1817) to characterize indeterminate muscle growth during early life. We hypothesized that up to 29 months post hatch (MPH), SC numbers and mitotic activity, the mitotic cycle duration of SCs, fiber morphology, and the volume of cytoplasmic domains around fiber nuclei would change during periods of fiber hypertrophy and hyperplasia. Single-fiber cultures were used in pulse-chase studies of SC division and the Pax7+ SC population. The number of SCs per fiber increased until 17 MPH, peaking as a proportion of fiber nuclei at 3 and 17 MPH. SC cycle time decreased in duration with age after peaks at 3 and 5 MPH. Domain volume was high at 1 and 29 MPH and low from 2 to 6 MPH. Fibers with uniformly tapered ends were most frequent at 4 MPH. Results suggest 3 and 6 –17 MPH as intervals for both SC proliferation and fiber hypertrophy, and that fiber growth alternated with new fiber formation (termed fiber hyperplasia) from 4 to 5 MPH and from 17 to 29 MPH. These patterns of cellular dynamics in lake sturgeon muscle growth advance our understanding of indeterm inate growth.
Source: Canadian Journal of Zoology - Category: Zoology Authors: Source Type: research