June 2015 (No. 1)
Gonadogenesis and slow proliferation of germ cells in juveniles of cultured yellowfin tuna, Thunnus albacores
Toru Kobayashi a, *, Tomoki Honryo b, Yasuo Agawa b, Yoshifumi Sawada b, Ileana Tapia c, Karla A. Macìas c, Amado Cano c, Vernon P. Scholey d, Daniel Margulies d, Naoki Yagishita a
a Laboratory for Aquatic Biology, Faculty of Agriculture, Kinki University, Japan
b Fisheries Laboratory of Kinki University, Japan
c Autoridad de los Recursos Acuáticos de Panamá (ARAP), Panama
d Inter American Tropical Tuna Commission (IATTC), Panama
To develop techniques for seedling production of yellowfin tuna, the behavior of primordial germ cells (PGCs) and gonadogenesis were examined at 1–30 days post hatching (dph) using morphometric analysis, histological examination, and in situ hybridization. Immediately after hatching, PGCs were located on the dorsal side of the posterior end of the rectum under the peritoneum of the larvae, and at 3 dph they came into contact with stromal cells. PGCs and stromal cells gradually moved forward from the anus prior to 5 dph. At 7–10 dph, germ cells were surrounded by stromal cells and the gonadal primordia were formed. In individu-als collected at 12 dph, PGCs were detected by in situ hybridization using a vasa mRNA probe that is a germ-cell-specific detection marker. The proliferation of germ cells in the gonadal primordia began at 7–10 dph. We observed double the number of germ cells at 30 dph (22 ± 3.2 cells), compared to that at 1 dph (11 ± 2.1 cells). Therefore, based on our data and previous reports, the initial germ cell proliferation of yellowfin tuna is relatively slower than that of other fish species.
Reproductive Biology 2015, 15 (2):
* Corresponding author at: Laboratory for Aquatic Biology, Department of Fisheries, Graduate School of Agriculture, Kinki University, Nara 631-8505, Japan. E-mail address: email@example.com (T. Kobayashi).