Transcriptional responses in a Drosophila defensive symbiosis
Transcriptional responses in a Drosophila defensive symbiosis
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DOI：
10.1111/mec.12603
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发表时间：
2014-03-01
影响因子：
4.9
通讯作者：
Perlman, Steve J.
中科院分区：
文献类型：
--
作者：
Hamilton, Phineas T.;Leong, Jong S.;Perlman, Steve J.
遗传性共生体在昆虫中普遍存在，可能对其宿主的健康产生重要影响。许多遗传性共生体可以保护宿主免受寄生虫或其他天敌的侵害。然而，大多数共生体提供保护的方式实际上是未知的。我们研究了最近发现的共生体介导的保护案例中的防御机制，其中细菌共生体螺原体保护果蝇新睾蝇免受剧毒线虫寄生虫霍华德拉·奥罗尼菲姆（Howardula aoronymphium）的侵害。利用螺原体感染强度的定量PCR和全转录组测序，我们试图区分以下防御模式：共生体-寄生虫竞争、宿主免疫启动和螺原体产生毒性因子。我们的研究结果并不支持Howardula和螺原体之间利用竞争来介导防御的模型，我们也没有发现对螺原体感染期间宿主免疫启动的有力支持。有趣的是，我们恢复了螺原体编码的假定毒素的序列，包括一种新的假定核糖体失活蛋白，其转录物响应线虫暴露而上调。通过产生毒素进行保护可能是昆虫遗传性防御共生中广泛使用且重要的机制。
Inherited symbionts are ubiquitous in insects and can have important consequences for the fitness of their hosts. Many inherited symbionts defend their hosts against parasites or other natural enemies; however, the means by which most symbionts confer protection is virtually unknown. We examine the mechanisms of defence in a recently discovered case of symbiont-mediated protection, where the bacterial symbiont Spiroplasma defends the fly Drosophila neotestacea from a virulent nematode parasite, Howardula aoronymphium. Using quantitative PCR of Spiroplasma infection intensities and whole transcriptome sequencing, we attempt to distinguish between the following modes of defence: symbiont-parasite competition, host immune priming and the production of toxic factors by Spiroplasma. Our findings do not support a model of exploitative competition between Howardula and Spiroplasma to mediate defence, nor do we find strong support for host immune priming during Spiroplasma infection. Interestingly, we recovered sequence for putative toxins encoded by Spiroplasma, including a novel putative ribosome-inactivating protein, transcripts of which are up-regulated in response to nematode exposure. Protection via the production of toxins may be a widely used and important mechanism in heritable defensive symbioses in insects.