Cloning and expression of the SPARC cDNA from rainbow trout

A trout SPARC cDNA has been isolated and the sequence is highly conserved. The encoded protein shows 76% identity and 91% similarity between trout and human. Like the frog protein, trout SPARC deduced protein has one potential N-glycosylation site in position 96. SPARC mRNA was detected from brain tissue as early as hatching day. The transcript level increased rapidly during the early postnatal period and maintained high levels in adulthood. By week 7, the mRNA level was 11 times higher than that at hatching day. The pituitary gland showed a strong signal of SPARC mRNA, and it was detected also with high expression in muscle, gill and brain, and at the lowest level in the liver. These results demonstrate that SPARC is widely distributed in trout and suggest that SPARC has multiple functions. It may play a critical role in early brain development, such as cell migration, proliferation and angiogenesis. It is proposed also that SPARC modulates pituitary hormone release through regulation of the degradation of the extracellular matrix. (C) 1997 The Fisheries Society of the British Isles.