Meeting Abstract
2.3 Monday, Jan. 4 Electrical activity-dependent regulation of muscle gene expression in the electric organ after chronic stimulation in live Sternopygus macrurus MANSHAD, Ahmad/S.*; SALAZAR, Evan/E.; GÜTH, Robert; UNGUEZ, Graciela/A.; New Mexico State University; New Mexico State University; New Mexico State University; New Mexico State University amanshad@gmail.com
Skeletal muscle responds to changes in electrical activity by modifying its phenotypic properties. An extreme case of activity-dependent muscle plasticity occurs in electric fish whereby some differentiated skeletal muscle fibers convert into the non-contractile, current-producing cells (electrocytes) of the electric organ (EO). In the gymnotiform S. macrurus, mature EO down-regulates some, but not all muscle-specific genes, and neural activity is required to maintain this phenotype of electrocytes as removal of neural input results in the re-expression of sarcomeric proteins (Unguez & Zakon, 1998). The activity-dependent molecular mechanisms regulating the expression of select muscle-specific genes in the EO are not known. To test the hypothesis that the pattern of neural activity regulates muscle genes in EO, we will investigate the correlation between different activation patterns and expression levels of genes in molecular pathways that control the muscle program. To date, we have developed a system to chronically stimulate EO in live fish at frequencies of 10-300 Hz. After removal of endogenous neural input by spinal transection, electrodes were implanted subcutaneously in EO (N=3 fish) and stimulation sustained for at least 3 days. Preliminary data suggest no tissue damage beyond electrode placement (N=1). These results are novel in that we have created the first device for chronic stimulation of myogenic tissues in live fish. We will begin characterizing changes in molecular pathways known to regulate muscle phenotype (Kim et al., 2004; 2008) after chronic stimulation for up to 2 weeks with EO and muscle-like stimulation patterns.
