黑胸敗血芽孢桿菌（Bacillus bombyseptieus,，Bb）是一種典型的革蘭氏陽性細(xì)菌,，是家蠶生長過程中通過自然感染引起病變的主要病原之一。2009年12月1日,，PLoS ONE發(fā)表了西南大學(xué)和四川農(nóng)科院的研究成果,，報道了鱗翅目模式昆蟲家蠶對病原細(xì)菌黑胸敗血芽孢桿菌侵染的分子應(yīng)答特征。
研究人員在基因組水平上分析了家蠶在感染Bb前后的基因表達變化,。結(jié)果顯示,，在Bb感染后24小時,，2436個基因（占家蠶全基因組14632個基因的17%）的表達發(fā)生了至少2倍的上調(diào)或下調(diào)變化,，其中1403個基因在多種幼蟲組織，特別是在中腸中表達,。這些表達發(fā)生變化的基因主要分為酶催化活性,、結(jié)合與轉(zhuǎn)運、生物學(xué)過程調(diào)節(jié)等14類,，參與了遺傳信息加工和轉(zhuǎn)錄,、糖代謝、氨基酸和氮代謝,、核苷酸代謝,、輔因子和維生素代謝以及體內(nèi)異物的生物降解和代謝等6類基礎(chǔ)代謝途徑。這表明即使只有一種病原侵染,，也會引起寄主昆蟲全基因組水平上的廣泛應(yīng)答,。
有趣的是，和蘇云金芽孢桿菌（Bt）相似,，Bb也能夠誘導(dǎo)蠶對毒素相關(guān)的應(yīng)答反應(yīng),，比如，編碼中腸圍食膜隔膜蛋白氨基肽酶N受體和鈉/鈣調(diào)蛋白的基因就被誘導(dǎo)表達,。不僅如此,，本研究還首次發(fā)現(xiàn)Bb能誘導(dǎo)激素合成和代謝途徑相關(guān)基因的上調(diào)表達，可能與Bb在蠶體內(nèi)的繁殖相關(guān),。另外,，Bb也能夠觸發(fā)家蠶的免疫應(yīng)答，包括細(xì)胞免疫、絲氨酸蛋白酶黑色素級聯(lián)反應(yīng)和體液免疫,；特別重要的是,，Bb能通過Toll途徑誘導(dǎo)蠶產(chǎn)生系統(tǒng)性免疫應(yīng)答，導(dǎo)致大量抗菌肽基因（如Attacin,、Lebocin,、Enbocin、Gloverin和Moricin）在Bb感染后24小時上調(diào)表達,。該研究首次在基因組水平上揭示了病原微生物侵染對鱗翅目昆蟲（蠶）生理代謝及免疫反應(yīng)的全面影響,，為我們深入理解病原和寄主昆蟲之間的相互關(guān)系，以及開發(fā)提高宿主昆蟲防病抗病能力的新舉措提供了重要線索,。
該研究是在西南大學(xué)家蠶基因組研究團隊夏慶友教授的指導(dǎo)下,，由博士研究生黃璐琳等完成，得到了國家“973”計劃和長江學(xué)者創(chuàng)新團隊項目的資助,。(生物谷Bioon.com)
Science：家蠶基因組測序成功
生物谷推薦原始出處：
PLoS ONE 4(12): e8098. doi:10.1371/journal.pone.0008098
A Genome-Wide Survey for Host Response of Silkworm, Bombyx mori during Pathogen Bacillus bombyseptieus Infection
Lulin Huang1,3, Tingcai Cheng2, Pingzhen Xu1, Daojun Cheng1, Ting Fang1, Qingyou Xia1,2*
1 Institute of Sericulture and Systems Biology, Southwest University, Chongqing, China, 2 Institute of Agronomy and Life Science, Chongqing University, Chongqing, China, 3 Institute of Economic Crops Breeding and Cultivation, Sichuan Academy of Agricultural Sciences, Chengdu, China
Host-pathogen interactions are complex relationships, and a central challenge is to reveal the interactions between pathogens and their hosts. Bacillus bombysepticus (Bb) which can produces spores and parasporal crystals was firstly separated from the corpses of the infected silkworms (Bombyx mori). Bb naturally infects the silkworm can cause an acute fuliginosa septicaemia and kill the silkworm larvae generally within one day in the hot and humid season. Bb pathogen of the silkworm can be used for investigating the host responses after the infection. Gene expression profiling during four time-points of silkworm whole larvae after Bb infection was performed to gain insight into the mechanism of Bb-associated host whole body effect. Genome-wide survey of the host genes demonstrated many genes and pathways modulated after the infection. GO analysis of the induced genes indicated that their functions could be divided into 14 categories. KEGG pathway analysis identified that six types of basal metabolic pathway were regulated, including genetic information processing and transcription, carbohydrate metabolism, amino acid and nitrogen metabolism, nucleotide metabolism, metabolism of cofactors and vitamins, and xenobiotic biodegradation and metabolism. Similar to Bacillus thuringiensis (Bt), Bb can also induce a silkworm poisoning-related response. In this process, genes encoding midgut peritrophic membrane proteins, aminopeptidase N receptors and sodium/calcium exchange protein showed modulation. For the first time, we found that Bb induced a lot of genes involved in juvenile hormone synthesis and metabolism pathway upregulated. Bb also triggered the host immune responses, including cellular immune response and serine protease cascade melanization response. Real time PCR analysis showed that Bb can induce the silkworm systemic immune response, mainly by the Toll pathway. Anti-microorganism peptides (AMPs), including of Attacin, Lebocin, Enbocin, Gloverin and Moricin families, were upregulated at 24 hours post the infection.
