Permalink : http://hdl.handle.net/2115/45199

ハシリショウジョウバエの一種, Chymomyza costataは北半球の冷温帯と亜寒帯に広く分布し, ショウジョウバエ科の中では珍しく, 幼虫で休眠し越冬する. 幼虫休眠の誘導には短日が有効で, 札幌産では臨界日長が14時間付近にある. 臨界日長はどのように計られるのだろうか? 「光周反応の測時機構に概日時計が関わっている」というBünning（1936）の仮説があり, この証明を目指して行ったC. costataにおける遺伝子組換え実験の概要を紹介する. ターゲットにした遺伝子はtimelessで, piggyBacと呼ばれるトランスポゾン由来の遺伝子組換えベクターを介して, timelessの強制発現系統やノックアウト系統を確立した.
A drosophilid fly, Chymomyza costata is living in the cool temperate and subarctic zones of the Northern Hemisphere. This species enters winter diapause at the larval stage in contrast to most of other drosophilid species. Short-day photoperiods are effective for the induction of larval diapause. The critical photoperiod of a wild-type strain collected in Sapporo is about 14 hours. How is the length of day or night measured? Bünning (1936) has proposed a hypothesis that the photoperiodic time measurement system involves the circadian clock. To test this hypothesis, I prepared two transgenic lines of C. costata. In these lines, the expression of a circadian clock gene, timeless, was enhanced or inhibited with heat shock treatment. The germline transformation was mediated by a lepidopteran transposon, piggyBac.