Program and Abstracts(PDF)

Annotated Bibliography of Key Works
1. Selvaraj S., H. Kitano, Y. Fujinaga, H. Ohga, M. Yoneda, A. Yamaguchi, A. Shimizu, and M.
Matsuyama. 2010. Molecular characterization, tissue distribution, and mRNA expression
profiles of two Kiss genes in the adult male and female chub mackerel (Scomber japonicus)
during different gonadal stages. Gen. Comp. Endocrinol. DOI:10.1016/j.ygcen.2010.07.011.
The full-length cDNAs of Kiss1 and Kiss2 in the chub mackerel were cloned and sequenced.
Chub mackerel K iss1 and Kiss2 cDNAs encode 105 and 123 amino acids, respectively. A
comparison of the deduced amino acid sequences of chub mackerel Kiss1 and Kiss2 with those of
other vertebrate species showed a high degree of conservation only in the kisspeptin-10 region
(Kp-10). The Kp-10 of chub mackerel Kiss1 (YNFNSFGLRY) and Kiss2 (FNFNPFGLRF)
showed variations at three amino acids. The mRNA expression profiles of Kiss1 and Kiss2 in the
brain, pituitary, and gonads at different gonadal stages suggested the possible involvement of two
Kiss genes in the brain and Kiss1 in the gonads of chub mackerel during seasonal gonadal
development.
2. Selvaraj S., H. Kitano, Y. Fujinaga, M. Amano, A. Takahashi, A. Shimizu, M. Yoneda, A.
Yamaguchi, and M. Matsuyama. 2009. Immunological characterization and distribution of
three GnRH forms in the brain and pituitary gland of chub mackerel (Scomber japonicus).
Zool. Sci. 26: 828-839.
This study reports on the presence of three GnRH forms in the brain of the chub mackerel,
Scomber japonicus, namely, salmon GnRH (sGnRH), chicken GnRH-II (cGnRH-II), and
seabream GnRH (sbGnRH), as confirmed by combined high performance liquid chromatography
(HPLC) and time-resolved fluoroimmunoassay (TR-FIA). Immunocytochemical localization of
the three GnRH forms in the brain was investigated by using specific antisera, to elucidate
possible roles of each GnRH form in reproduction in this species, and double immunolabeling
was used to localize GnRH-ir (immunoreactive) fibers innervating the pituitary. The results of the
study indicated that multiple GnRH forms serve different functions, with sbGnRH having a
significant role in reproduction in stimulating FSH- and LH-producing cells, and sGnRH and
cGnRH-II serving as neurotransmitters or neuromodulators.
3. Shiraishi T., S.D. Ketkar, H. Kitano, M. Nyuji, A. Yamaguchi, and M. Matsuyama. 2008. Time
course of final oocyte maturation and ovulation in chub mackerel Scomber japonicus induced
by hCG and GnRHa. Fish. Sci. 74: 764-769.
The question of whether the ovulation and spawning time in chub mackerel Scomber
japonicus is entrained by a circadian rhythm was tested by administering human chorionic
gonadotropin (hCG) and gonadotropin-releasing hormone analogue (GnRHa) at two ‘opposite’
times, 14:00 and 02:00 hours, and the time courses of FOM and ovulation were compared. When
hCG was injected, ovulation occurred 33 h post-injection in both groups. Similarly, ovulation
began at 36 h post-injection of GnRHa, regardless of the timing of injection. These results
indicated that timing of ovulation in chub mackerel depends on the timing of luteinizing hormone
(LH) stimulation.
4. The following are published reports of our reproductive studies in chub mackerel:
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