involvement of Ad4BP/SF-1 was investigated using the serial sex changing goby Trimma okinawae. First, a cDNA encoding Ad4BP/SF-1 was cloned from ovarian follicles. The open reading frame of goby Ad4BP/SF-1 encodes a protein of 489 amino acids. Ad4BP/SF-1 was expressed in gonadal tissues, brain, and kidney. Second, transcript levels of Ad4BP/SF-1 were measured in the ovary and testis of the same individuals. Expressions were related to sexual phases. Moreover, ovarian expression of Ad4BP/SF-1 increased during vitellogenesis and declined sharply during the post-vitellogenic period. Finally, the expression profile of Ad4BP/SF-1 was measured during serial sex change in the ovary. Ad4BP/SF-1 increased in parallel with the onset of the female-phase and decreased as female became male. Therefore, Ad4BP/SF-1 probably acts as an important indirect regulator of oocyte growth and maturation at female-phase of serial sex changing gobiid fish T okinawae. (c) 2005 Elsevier Inc. All rights reserved.