Molecular cloning and histological localization of LH-like substances in a bottlenose dolphin (Tursiops truncatus) placenta.
All mammals exhibit pituitary-specific expression of LH and FSH, whereas placental expression of gonadotropins has been reported only in primates and equids. Some cetaceans, such as dolphins, have a long gestational period and a sexual cycle of about 27 days almost comparable with that of humans. Histologically, dolphins have an epitheliochorial placentae that resembles placentas of Perissodactyla including horses. In the present study, we cloned cDNAs encoding gonadotropins and observed their immunohistochemical localization in the placenta of bottlenose dolphin. The cDNAs obtained encoded 120 amino acids for the alpha-subunit (including 96 amino acids of mature proteins), and 141 amino acids for the beta-subunit (including 121 amino acids of mature proteins). The sequence of the alpha-subunit was similar to that in the pig (Artiodactyla) pituitary glycoprotein hormone [96.7% homology at amino acids (aa) level], and the sequence of the beta-subunit was similar to that of luteinizing hormone (LH) in the pig [94.3% homology at aa level] and white rhinoceros (Perissodactyla) [93.3% homology at aa level]. Of interest, dolphin LHbeta lacks carboxyl-terminal-peptides (CTP). This fact suggests that CTP are not essential for placental expression of gonadotropin in dolphins. Immunohistochemical observations employing anti-ovine LHbeta antibody revealed positive staining in the villositycal tissue. Our observations suggest placental expression of gonadotropin homologues in cetaceans and possible evolutionary conservation of placentae-derived hormonal control of ovarian functions during pregnancy.
Watanabe
Nozomi
N
Department of Infectious Disease Control, Nihon University Advanced Medical Research Center, 30-1 Ohyaguchi-Kamimachi Itabashi-ku, Tokyo, 173-8610, Japan.
Hatano
Jun
J
Asahina
Kiyoshi
K
Iwasaki
Toshihide
T
Hayakawa
Satoshi
S
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D050681:Bottle-Nosed Dolphin / Q000502:physiology*; D003001:Cloning, Molecular; D005260:Female; D015292:Glycoprotein Hormones, alpha Subunit / Q000737:chemistry; D007150:Immunohistochemistry; D007986:Luteinizing Hormone / Q000032:analysis / Q000235:genetics*; D037101:Luteinizing Hormone, beta Subunit / Q000737:chemistry; D008969:Molecular Sequence Data; D010802:Phylogeny; D010920:Placenta / Q000737:chemistry*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013552:Swine
D015292:Glycoprotein Hormones, alpha Subunit; D037101:Luteinizing Hormone, beta Subunit; D007986:Luteinizing Hormone