Fig. 1. RNase protection assay reveals the expression of RyR1-slow in heater tissue. A ³²P-labeled RNA probe, synthesized from a blue marlin extraocular muscle clone, hybridized to slow-twitch skeletal muscle and heater organ but not to fast-twitch skeletal muscle. This isoform was named RyR1-slow to distinguish it from RyR1-fast, which is expressed in fish fast-twitch skeletal muscle. The probe was hybridized to 20 µg total RNA from each tissue. Yeast, control RNA; TFSB, toadfish fast-twitch swimbladder muscle; BMCard, blue marlin cardiac muscle; SFHO, swordfish heater organ; BMST, blue marlin slow-twitch skeletal muscle; BMFT, blue marlin fast-twitch skeletal muscle; BMHO, blue marlin heater organ.