Regeneration mechanism of hemopoietic organs in the silkworm, , after heavy-ion irradiation; Analysis by transplantation of the irradiated organs using a transgenic silkworm strain

Shirai, Koji*; Kiguchi, Kenji*; Sakata, Toshiyuki*; Fukamoto, Kana; Sakashita, Tetsuya; Funayama, Tomoo; Hamada, Nobuyuki*; Kobayashi, Yasuhiko

Locally-targeted irradiation of the silkworm, Bombyx mori, with heavy-ions resulted in marked damage of the larval hemopoietic organs (HPOs), but that these were subsequently regenerated with high frequency. In order to clarify the origin of the stem cells responsible for the regeneration of heavy-ion-irradiated HPOs, we conducted transplantation experiments of the organs using transgenic silkworm larvae, which were characterized by GFP expression in cells. Here we suggest that the stem cells responsible for regeneration may also originate from the hemocytes in circulation. The implanted organs were recovered from the host larvae six days. Then GEP in the regenerated organs was immunohistochemically detected by using anti-GFP. As a result, GFP-signals were clearly detected in those HPOs that regenerated after heavy-ion irradiation. This finding suggests that the hemocytes expressing GFP in circulation, invade the implanted HPOs where they are involved in regeneration.