Molecular cloning and expression of two closely related GTP-binding proteins from zebrafish.

Developmentally regulated GTP-binding proteins (DRGs) are a subclass of GTP-binding proteins that have been discovered recently. Here we report two zebrafish DRG cDNA clones closely related to human and mouse DRG genes. The two DRG sequences showed a high degree of similarity (55% identity, 72% similarity) at the amino acids level. Whole mount in situ hybridization revealed expression of zebrafish DRGs maternally, following the onset of zygotic transcription at the mid-blastula transition (MBT) and throughout embryonic. The expression of these two genes in different tissues follows a similar pattern, suggesting that they may serve a similar function.

Molecular cloning and expression of a smooth muscle-specific gene SM22alpha in zebrafish.

SM22alpha is a kind of 22-kDa protein which is exclusively expressed in smooth muscle containing tissues of the vertebrates. Here we report molecular cloning of a novel zebrafish SM22alpha gene. The full length of zebrafish SM22alpha cDNA is 1296bp and it encodes a polypeptide of 201 amino acids which shares 69.2%, 69.7%, 69.2%, 67.2%, and 61.2% overall identity with human, mouse, rat, chicken, and bovine SM22alpha, respectively. Characterization of zebrafish SM22alpha genomic sequence reveals that it spans 7.7kb and contains five exons and four introns. The expression pattern of SM22alpha in zebrafish embryonic development is studied by whole-mount in situ hybridization. Strong expression is observed in vascular, gut, swim bladder, branchial arches, and fin epidermis. Furthermore, we carry out gene knock-down by antisense morpholino oligonucleotide, which results in disappearance of yolk extension, caudal fin aberrance, and deficiency of circulation system in zebrafish embryo. Cross-section of SM22alpha-deficient embryo suggests that SM22alpha may play roles in smooth muscle cell morphology transform.