Follicle-stimulating
hormone b, luteinizing hormone b and glycoprotein hormone a subunit
mRNA levels in artificially maturing Japanese eel Anguilla japonica
and naturally maturing New Zealand longfinned eel Anguilla dieffenbachii
K. Saito, P.M. Lokman, G. Young, Y. Ozak,
H. Matsubara, H. Okumura, Y. Kazeto, Y. Yoshiura, K. Aida, S. Adachi, K.
Yamauchi-2003
Fisheries
Science, 69(1):
146
Abstract:
cDNAs for three subunits of gonadotropin,
namely follicle-stimulating hormone (FSH)b, luteinizing hormone (LH) b and glycoprotein hormone (GP) a, of the New Zealand longfinned eel Anguilla dieffenbachii
were cloned. Based on their nucleotide sequences, which were more than 98%
identical to those of the Japanese eel Anguilla japonica, a real-time
reverse transcription-polymerase chain reaction method for the quantitative
assay of gonadotropin subunit mRNAs of the two eel species was developed
using the same primer sets. Accordingly, changes in pituitary gonadotropin
mRNA levels were analyzed in female Japanese eels induced to develop
artificially by salmon pituitary homogenate (SPH) treatment and in naturally
maturing female New Zealand longfinned eels collected from the wild. In
Japanese eels, the FSH b mRNA level was very high at the
previtellogenic stage (PV) and decreased remarkably after SPH injection,
whereas the reverse was seen in New Zealand longfinned eels. The mRNA levels
of LH b and GP a increased during gonadal
development in both species, albeit to a much greater extent in Japanese
eels. As the Japanese and New Zealand longfinned eels are closely related
species of the same genus, the different gonadotropin expression patterns
are likely to reflect differences in maturational conditions rather than
species. Our findings are indicative of aberrant gonadal development and may
explain the poor quality eggs obtained from artificially matured Japanese
eels.
(Division of Marine Biosciences, Graduate School of
Fisheries, Hokkaido University, Hakodate, Hokkaido 041-8611, Japan, Tel:
81-11-706-5166. Fax: 81-11-706-7821. Email: k-saito@med.hokudai.ac.jp)