據(jù)物理學(xué)家組織網(wǎng)報(bào)道，眾所周知,，飛蛾和蝴蝶,，尤其是家蠶，是產(chǎn)絲的好手,。我們也都知道蜘蛛吐絲結(jié)網(wǎng),。但是它們并不是無(wú)脊椎動(dòng)物中唯一利用這種強(qiáng)壯的多功能絲的動(dòng)物。澳大利亞聯(lián)邦工業(yè)與科技研究所昆蟲(chóng)學(xué)系的塔拉·薩瑟蘭博士和她的科研組,，正在尋找由其他昆蟲(chóng)吐絲的方法,，他們的研究結(jié)果發(fā)表在最近的《分子生物學(xué)和進(jìn)化學(xué)》雜志上，論文名稱為《卷曲螺旋絲基本結(jié)構(gòu)特征守恒(Conservation of Essential Design Features in Coiled Coil Silks)》,。
薩瑟蘭博士說(shuō)：“大部分人沒(méi)意識(shí)到蜜蜂和螞蟻也能產(chǎn)絲,，但是它們確實(shí)能，而且它們的分子結(jié)構(gòu)與飛蛾和蜘蛛絲中較大的蛋白質(zhì),、薄片結(jié)構(gòu)非常不同,。繭和巢絲看起來(lái)是由卷曲螺旋(一種蛋白質(zhì)排列結(jié)構(gòu)，由多重螺旋狀絲彼此纏繞)狀結(jié)構(gòu)組成,。這種結(jié)構(gòu)讓絲的重量更輕,、韌度更強(qiáng)。我們已經(jīng)鑒別出蜜蜂的絲蛋白基因,，現(xiàn)在我們正在鑒別并為大黃蜂,、公牛蟻和織工蟻的絲蛋白基因排序，并將它們與蜜蜂的絲蛋白基因進(jìn)行對(duì)比,。我們從中確定了這些昆蟲(chóng)結(jié)網(wǎng)或繭所必需的結(jié)構(gòu)元素,，以及卷曲螺旋狀絲的功能。為了做這些,，我們鑒別了繭的卷曲螺旋狀蛋白質(zhì)和其他橫跨群居膜翅目昆蟲(chóng)分子進(jìn)化樹(shù)的物種的巢絲,，并將它們進(jìn)行對(duì)比。”
蜜蜂和螞蟻產(chǎn)生高性能絲,，雖然這些物種的絲都是由幼蟲(chóng)產(chǎn)生,，而且是相同的腺體產(chǎn)生，但是它們的用途卻各不相同,。蜜蜂幼蟲(chóng)產(chǎn)絲是為了加固蜂房,，它們將在這里化蛹；公牛蟻幼蟲(chóng)織繭是為了在它們化蛹時(shí),，用來(lái)保護(hù)自己,；大黃蜂幼蟲(chóng)在蜂房?jī)?nèi)造繭，它們化蛹后,，這些繭將被用來(lái)儲(chǔ)存花粉和 蜂蜜,；織工蟻把它們的幼蟲(chóng)當(dāng)作“工具”,，用它們吐得絲將新鮮植物的葉子捆扎在一塊，形成一個(gè)龐大的公共巢穴,。與傳統(tǒng)的薄片絲相比,，這些昆蟲(chóng)群體的絲經(jīng)過(guò)進(jìn)化，變得更加堅(jiān)韌和穩(wěn)定,。也許這種不同尋常的物質(zhì)的進(jìn)化,，為群居膜翅目昆蟲(chóng)的發(fā)展壯大打下了堅(jiān)實(shí)基礎(chǔ)。卷曲螺旋狀絲在有刺的群居昆蟲(chóng)(即那些有刺但不屬于有刺寄生蜂的昆蟲(chóng))中非常常見(jiàn),。這些群居昆蟲(chóng)促進(jìn)了進(jìn)化樹(shù)的發(fā)展，顯然這種卷曲螺旋狀絲在1.55億年前就得到了進(jìn)化,。(新浪科技 楊孝文）
原始出處:
MBE Advance Access originally published online on August 16, 2007
Molecular Biology and Evolution 2007 24(11):2424-2432; doi:10.1093/molbev/msm171
Conservation of Essential Design Features in Coiled Coil Silks
Tara D. Sutherland*, Sarah Weisman*, Holly E. Trueman*, Alagacone Sriskantha*, John W. H. Trueman and Victoria S. Haritos*
* CSIRO Entomology, Canberra, ACT, Australia
School of Botany and Zoology, Australian National University, Canberra, ACT, Australia
E-mail: [email protected] .
Accepted for publication August 14, 2007.
Silks are strong protein fibers produced by a broad array of spiders and insects. The vast majority of known silks are large, repetitive proteins assembled into extended ß-sheet structures. Honeybees, however, have found a radically different evolutionary solution to the need for a building material. The 4 fibrous proteins of honeybee silk are small (30 kDa each) and nonrepetitive and adopt a coiled coil structure. We examined silks from the 3 superfamilies of the Aculeata (Hymenoptera: Apocrita) by infrared spectroscopy and found coiled coil structure in bees (Apoidea) and in ants (Vespoidea) but not in parasitic wasps of the Chrysidoidea. We subsequently identified and sequenced the silk genes of bumblebees, bulldog ants, and weaver ants and compared these with honeybee silk genes. Each species produced orthologues of the 4 small fibroin proteins identified in honeybee silk. Each fibroin contained a continuous predicted coiled coil region of around 210 residues, flanked by 23–160 residue length N- and C-termini. The cores of the coiled coils were unusually rich in alanine. There was extensive sequence divergence among the bee and ant silk genes (<50% similarity between the alignable regions of bee and ant sequences), consistent with constant and equivalent divergence since the bee/ant split (estimated to be 155 Myr). Despite a high background level of sequence diversity, we have identified conserved design elements that we propose are essential to the assembly and function of coiled coil silks.
Key Words: silk • coiled coils • bees • ants • social insects
