生物谷報(bào)道：鳳蝶的幼蟲經(jīng)過幾次蛻皮后,，顏色會(huì)突然從黑白變?yōu)轷r艷的綠色,。日本科學(xué)家發(fā)現(xiàn),，幼蟲體內(nèi)保幼激素量的變化改變了基因的作用方式，從而促使幼蟲變色,。
鳳蝶幼蟲起先身披黑白相間斑紋,，全身遍布瘤一樣的凸起，它們以此偽裝成鳥類的糞便,，躲避天敵,。而幼蟲第四次蛻皮后，卻變成可以融入周圍草木的鮮艷的綠色,，身上的凸起也消失了,，因?yàn)樗鼈冮L大一些后如果依然是鳥類糞便的樣子，反而比較顯眼,。這個(gè)過程中,，促使幼蟲變色的機(jī)制以前一直沒有得到解釋。
日本東京大學(xué)教授藤原晴彥等人在新一期美國《科學(xué)》雜志上報(bào)告說,，他們發(fā)現(xiàn)保幼激素與此相關(guān),。研究人員測量了幼蟲體內(nèi)的激素水平，發(fā)現(xiàn)保幼激素在幼蟲體內(nèi)的濃度在第三次蛻皮后的約１天內(nèi)直線下降,，這種變化導(dǎo)致幼蟲第四次蛻皮后變色,。而如果在剛完成第三次蛻皮的幼蟲身上涂抹保幼激素,，那么這些幼蟲第四次蛻皮之后其身體斑紋依然是黑白相間。研究人員因此認(rèn)為,，保幼激素的濃度是鳳蝶幼蟲變色的關(guān)鍵,。
保幼激素是昆蟲在發(fā)育過程中分泌的一種激素，能抑制成蟲特征出現(xiàn),，使幼蟲蛻皮后仍保持幼蟲狀態(tài),。（新華網(wǎng)）
生物谷推薦英文原文：
Science 22 February 2008:
Vol. 319. no. 5866, p. 1061
DOI: 10.1126/science.1149786
Juvenile Hormone Regulates Butterfly Larval Pattern Switches
Ryo Futahashi1,2 and Haruhiko Fujiwara1*
Insect color patterns can be very diverse. This variation is also seen among many larval instar stages, which can take on vastly different phenotypes. Young caterpillars of the swallowtail butterfly, Papilio xuthus, are mimics of bird droppings, whereas the fifth larval instar is camouflaged among the leaves of host plants (cryptic pattern). We find that juvenile hormone (JH) titers decrease during the fourth larval instar. Furthermore, treatment with JH analog at the beginning of the fourth instar stage resulted in reproducing the mimetic pattern instead of the usual cryptic one and likewise altered gene expression patterns to that associated with the mimetic pattern. These findings suggest that JH regulates the progressive larval pattern switch of this insect.
1 Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Bioscience Building 501, Kashiwa, Chiba 277-8562, Japan.
2 National Institute of Agrobiological Sciences, 1-2 Owashi, Tsukuba, Ibaraki 305-8634, Japan.
* To whom correspondence should be addressed. E-mail: [email protected]
