cDNA cloning of two gonadotropin beta subunits (GTH-Ibeta and -IIbeta) and their expression profiles during gametogenesis in the Japanese flounder (Paralichthys olivaceus).
To clarify the profiles of two distinct gonadotropin (GTH-I and -II) mRNA levels during gametogenesis in a multiple spawner, the Japanese flounder (Paralichthys olivaceus), the cDNAs encoding GTH-Ibeta and -IIbeta from the pituitary gland have been cloned and sequenced. The nucleotide sequence of GTH-Ibeta was 542 bp long, encoding 120 amino acids, and that of GTH-IIbeta was 554 bp long, encoding 145 amino acids. In females, Northern blot analysis has revealed that relative mRNA levels of GTH-Ibeta and -IIbeta were low in immature fish, showed a gradual increase with ovarian development, and reached the highest level at the maturation stage. Both GTH-Ibeta and -IIbeta mRNA levels were highly correlated with gonadosomatic index (GSI) values and with circulating estradiol-17beta and testosterone (T) levels. In males, the mRNA levels of GTH-Ibeta increased with the increase in GSI values and in circulating 11-ketotestosterone and T levels, whereas the mRNA levels of GTH-IIbeta did not show any correlation with GSI values and with circulating steroid levels, suggesting a difference in regulatory mechanisms of GTH-I and -II synthesis in males. The similar changes in GTH-Ibeta and -IIbeta mRNA levels during oogenesis are considered to be characteristic of GTH synthesis in multiple spawners, differing from the differential changes reported in annual spawners such as salmonids.
Kajimura
S
S
Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo, 113-8657, Japan.
Yoshiura
Y
Y
Suzuki
M
M
Aida
K
K
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D003001:Cloning, Molecular; D017931:DNA Primers; D018076:DNA, Complementary / Q000096:biosynthesis* / Q000235:genetics; D005260:Female; D005432:Flounder / Q000235:genetics*; D005718:Gametogenesis / Q000235:genetics*; D005786:Gene Expression Regulation / Q000235:genetics*; D012739:Gonadal Steroid Hormones / Q000096:biosynthesis; D006065:Gonadotropins, Pituitary / Q000096:biosynthesis* / Q000235:genetics; D008297:Male; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000096:biosynthesis; D011863:Radioimmunoassay
D017931:DNA Primers; D018076:DNA, Complementary; D012739:Gonadal Steroid Hormones; D006065:Gonadotropins, Pituitary; D012333:RNA, Messenger