담배거세미나방(Spodoptera litura) Chitinase gene의 RNA interference

RNA interference (RNAi) is the method which controls phenotypes of gene in live cells. Chitinase is the enzyme helping digestion and absorption of old cuticles during the ecdysis of insects. In order to investigate molting-inhibition effect with the chitinase related gene in Spodoptera litura, RNA was extracted from the $5^{th}$ instars. cDNA was synthesized and then we obtained about 700 bp size chitinase. After PCR products were cloned into a pGEM T-easy vector, colonies were picked. DNA was extracted from the colony cultures. EcoR I enzyme was used to check whether PCR products were inserted or not. And then we confirmed vector band of about 3 kb and insert band of about 700 bp. To synthesize the dsRNA, each DNA was cut with Spe I and Nco I enzymes (Circular DNA became lineared DNA). After synthesis of dsRNA, approximately 5 ul dsRNA was injected into the $3^{rd}$ abdominal segment of S. litura $4^{th}$ larvae. The concentration of dsRNA was about $10{\mu}g/{\mu}l$. We confirmed larval-larval molting : there were phenotypically abnormal individuals - for instance malformation, molting inhibition and change of integument color. Pupaadult molting : there were phenotypically abnormal individuals - for instance molting inhibition, change of wings and malformation. Also we could investigate the pupation, emergence and variation about noninjection, treated with DW and dsRNA. Each pupation was non-injection 83.3%, DW 78.3% and dsRNA 66.7%. Each emergence was non-injection 90.0%, DW 72.3% and dsRNA 65.0%. So we considered that chitinase dsRNA induced molting inhibition effect. But each variation was non-injection 8.9%, DW 2.9% and dsRNA 19.2%. Therefore dsRNA group showed the highest variation value. When 18 hours after injecting dsRNA, we could obtain abnormal individual. RNA interference(RNAi)는 살아있는 세포 내에서 유전자의 표현 형을 억제하는 작용을 하고 Chitinase는 곤충이 탈피를 하는 동안 오래된 큐티클의 분해와 재흡수를 도와주는 효소로 알려져 있다. 이러한 작용기작을 이용하는 연구를 수행하기 위하여 담배거세미나방의 chitinase와 관련하여 탈피저해 효과를 조사하였다. 담배거세미나방 5령 유충으로부터 RNA를 추출하고 이용하여 cDNA를 합성하고 약 700 bp의 chitinase를 증폭 하였다. 증폭한 PCR product를 pGEM T-easy vector에 cloning하여 competent cell (E.coli)에 형질전환 시키고 mixture를 배양 후 colony를 선발하고 plasmid DNA를 추출하였다. 그 결과 약 3 kb size의 vector band와 약 700 bp의 insert band를 확인 할 수 있었다. dsRNA를 합성하기 위해 각각의 DNA를 Spe I과 Nco I의 제한 효소 처리를 하여 linear form의 DNA로 만들었다. dsRNA 합성 후 약 $10{\mu}g/{\mu}l$의 농도로 $5{\mu}l$씩 담배거세미나방 4령 유충에 주입하였다. 그 결과 유충-유충간의 탈피에서는 기형발육, 탈피저해, 표피의 색소 변이가 나타났다. 번데기-성충 간의 탈피에서는 탈피저해, 날개변이, 기형발육 현상을 볼 수 있었다. 용화율의 경우