TRANSFORMING-GROWTH-FACTOR-BETA GENE-EXPRESSION IN AVIAN LOW SCORE NORMAL PECTORAL MUSCLE

The avian Low Score Normal (LSN) genetic muscle weakness is phenotypic ally characterized by a reduction in the ability of birds to right the mselves from a supine position. In previous studies, LSN birds exhibit ed elevated levels of decorin transcript and protein at embryonic Day 20 and a large increase in collagen crosslinking at 6 wk posthatch. Tr ansforming growth factor-beta (TGF-beta) expression has been reported to control decorin expression. Steady state levels of TGF-beta 1 and T GF-beta 2 transcripts were determined in ovo and posthatch in order to initiate an investigation of the mechanism underlying decorin express ion. On embryonic Day 20 through 1 wk posthatch, TGF-beta 2 transcript levels were elevated, whereas an increase in TGF-beta 1 was only note d at 1 d posthatch. These data suggest that the increase in decorin ex pression may be associated with a modification in a TGF-beta signal tr ansduction pathway.