CLONING AND EXPRESSION OF THE SPARC CDNA FROM RAINBOW-TROUT

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