日本產(chǎn)業(yè)技術(shù)綜合研究所在《美國國家科學(xué)院學(xué)報》網(wǎng)絡(luò)版上報告說,，他們發(fā)現(xiàn)臭蟲必須與一種寄生細(xì)菌共生，才能正常生長和繁殖,。這項成果將幫助人們防治臭蟲,。
從20世紀(jì)20年代起就有一些報告稱，臭蟲的精巢或卵巢附近有一種特殊細(xì)胞群,，里面的細(xì)胞內(nèi)存在大量細(xì)菌,。產(chǎn)業(yè)技術(shù)綜合研究所的研究人員以生長在日本和澳大利亞的105只臭蟲為研究對象，解剖它們精巢或卵巢附近的上述細(xì)胞群,，并進(jìn)行基因測試,，結(jié)果發(fā)現(xiàn)了名為尖音庫蚊沃爾巴克氏體的寄生細(xì)菌基因。研究人員說,，這說明105只臭蟲體內(nèi)都有這種寄生細(xì)菌,。
研究人員除去這些臭蟲體內(nèi)的尖音庫蚊沃爾巴克氏體，然后讓它們以吸食混入抗生物質(zhì)的血液為生,，結(jié)果這些臭蟲的卵的孵化率急劇下降,，即便孵化出幼蟲，也都不能發(fā)育為成蟲,。這表明,，感染尖音庫蚊沃爾巴克氏體對臭蟲的正常生長和繁殖非常重要。
那么,，尖音庫蚊沃爾巴克氏體到底為臭蟲提供了什么東西呢,？臭蟲以脊椎動物的血液為生,。血液看似營養(yǎng)豐富，實際上卻缺乏昆蟲所必需的B族維生素,。研究人員發(fā)現(xiàn),，在喂食臭蟲的血液中添加B族維生素，這樣即使臭蟲體內(nèi)的尖音庫蚊沃爾巴克氏體被清除,，臭蟲照樣能夠正常發(fā)育,。
大約60％至70％的昆蟲體內(nèi)都寄生著尖音庫蚊沃爾巴克氏體，而這次研究是人們首次發(fā)現(xiàn)這種寄生細(xì)菌與臭蟲有互利共生關(guān)系,。研究人員指出,，今后可以研制通過消除尖音庫蚊沃爾巴克氏體來防治臭蟲的方法。（生物谷Bioon.com）
生物谷推薦原始出處：
PNAS December 22, 2009, doi: 10.1073/pnas.0911476107
Wolbachia as a bacteriocyte-associated nutritional mutualist
Takahiro Hosokawa, Ryuichi Koga, Yoshitomo Kikuchi, Xian-Ying Meng and Takema Fukatsu1
National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8566, Japan
Many insects are dependent on bacterial symbionts that provide essential nutrients (ex. aphid–Buchnera and tsetse–Wiglesworthia associations), wherein the symbionts are harbored in specific cells called bacteriocytes that constitute a symbiotic organ bacteriome. Facultative and parasitic bacterial symbionts like Wolbachia have been regarded as evolutionarily distinct from such obligate nutritional mutualists. However, we discovered that, in the bedbug Cimex lectularius, Wolbachia resides in a bacteriome and appears to be an obligate nutritional mutualist. Two bacterial symbionts, a Wolbachia strain and an unnamed γ-proteobacterium, were identified from different strains of the bedbug. The Wolbachia symbiont was detected from all of the insects examined whereas the γ-proteobacterium was found in a part of them. The Wolbachia symbiont was specifically localized in the bacteriomes and vertically transmitted via the somatic stem cell niche of germalia to oocytes, infecting the incipient symbiotic organ at an early stage of the embryogenesis. Elimination of the Wolbachia symbiont resulted in retarded growth and sterility of the host insect. These deficiencies were rescued by oral supplementation of B vitamins, confirming the essential nutritional role of the symbiont for the host. The estimated genome size of the Wolbachia symbiont was around 1.3 Mb, which was almost equivalent to the genome sizes of parasitic Wolbachia strains of other insects. These results indicate that bacteriocyte-associated nutritional mutualism can evolve from facultative and prevalent microbial associates like Wolbachia, highlighting a previously unknown aspect of the parasitism-mutualism evolutionary continuum.
