Figure 2.

Developmental expression of β-spectrin, α-fodrin, and β-fodrin in rat skeletal muscle analyzed by Northern blot. RNAs were isolated from rat hindlimb muscle at different ages, fractionated on 1% agarose gels, and transferred to nylon membranes. Three different membranes were hybridized to cDNA probes specific for β-spectrin (A), β-fodrin (B), and α-fodrin (C). The membranes were then stripped and hybridized with probes to 18S rRNA to indicate the relative amounts of RNA loaded (shown at the bottom of each blot). After normalization against the rRNA signal, the level of expression of each message at each age was plotted relative to its corresponding adult value: A′, β-spectrin (only the 11-kb transcript is shown); B′, β-fodrin; C′, α-fodrin. The values were averages of at least three independent experiments; values for the mean ± SEM molecular size standards, indicated to the left of each blot, are (from top to bottom) 9.5, 7.5, 4.4, 2.4, and 1.4 kb. The developmental stages tested were E16, E18, and E19 (embyronic days 16, 18, and 19), P1 (postnatal day 1), and adult (A).