Figure 3.

Analysis of transgenic mice. (a) Specific expression of transgenes in skeletal muscle. Northern analysis of RNA samples prepared from female mice was carried out by using simian virus 40 sequences as a probe. On longer exposures of these blots, no expression of the transgenes was observed in liver, kidney, spleen, or heart in any of these lines. (b) Muscle analysis. Sections were stained with hematoxylin and eosin. The gastrocnemius and plantaris muscles are outlined (Left). Center shows higher magnifications of representative areas from the gastrocnemius muscle. Right shows distribution of fiber diameters. Each graph represents the composite of 450 fiber measurements from 3 animals (150 per animal), except for the F3 graph, which represents 175 measurements from the F3 founder animal. Standard deviations of fiber sizes were 9, 11, 11, and 13 μm for control, B32, C27, and F3 animals, respectively. Black and gray arrows show the mean fiber diameters for control and transgenic animals, respectively. Note that in each case, the mean fiber diameter was increased in the transgenic animals (P < 0.001).