Expression and localization of collagen type IV α1 chain in medaka ovary

概要

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A cDNA clone coding for collagen type IV α1 chain was obtained from the ovary of the medaka, Oryzias latipes. The clone encodes a protein of 1639 amino acids including a putative 21-residue signal peptide, and the deduced amino acid sequence of the α1 chain was homologous to those of the proteins from other species. Collagen type IV α1 chain mRNA was expressed in various tissues of the adult fish. In situ hybridization analysis revealed that the α1 chain mRNA was localized in the follicle layer of all growing follicles. In the post-ovulatory follicle that had released its oocyte in ovulation, the α1 chain transcript was detected in a winding line surrounding the tissue. This localization pattern was different from that of gelatinase B, a marker gene for granulosa cells. A specific antibody was prepared for the medaka collagen type IV α1 chain. Immunohistochemical analysis using this antibody yielded results consistent with those obtained by the in situ hybridization experiment. The current results indicate that in the medaka ovary, collagen type IV is synthesized by theca cells and is localized in the basement membrane.