Gene expression analysis of the endosymbiont-bearing midgut tissue during ontogeny of the carpenter ant Camponotus floridanus.
Gene expression analysis of the endosymbiont-bearing midgut tissue during ontogeny of the carpenter ant Camponotus floridanus.
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DOI：
10.1016/j.jinsphys.2013.03.011
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发表时间：
2013-06
影响因子：
2.2
通讯作者：
C. Ratzka;R. Gross;H. Feldhaar
中科院分区：
文献类型：
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作者：
C. Ratzka;R. Gross;H. Feldhaar
昆虫与细胞外和/或细胞内的细菌内共生体经常进化出互惠关系。内共生菌感染似乎影响宿主的几种细胞功能，如免疫途径、氧化应激调节和自噬。我们目前的知识，具体的主机因素导致内共生体的耐受性和/或控制仍然是稀缺的，是基于昆虫宿主和细菌之间的关联很少。Camponotus floridanus蚂蚁在称为细菌细胞的专门的中肠细胞内窝藏专性细胞内细菌Blochmannia floridanus。中肠组织内的Blochmannia内共生菌的数量在宿主发育过程中强烈增加，并在蛹后期达到最大值，整个中肠转化为共生器官。在工蜂羽化后，布氏花蝇的数量再次大幅减少。我们从C. floridanus可能参与宿主-共生体相互作用，这是基于它们与先前研究的来自其他昆虫的共生相关基因的显著同源性。我们确定了这些基因的表达，在内共生轴承中肠组织相比，残留的身体组织在不同的发展阶段的C。floridanus中，以揭示基因表达的变化与内共生体数量的变化每主机。引人注目的是，两种模式识别受体（酰胺酶PGRP-LB和PGRP-SC2）在蛹期的中肠组织中高度表达，可能下调IMD途径，使内共生体耐受。此外，我们还研究了蛹期对细菌攻击的免疫基因表达。结果表明，中肠组织的表达模式与残体不同。我们的研究结果支持了酰胺酶PGRP，特别是PGRP-LB，在调节C. floridanus和建议的溶酶体系统的控制Blochmannia内共生体的参与。
Insects have frequently evolved mutualistic relationships with extracellular and/or intracellular bacterial endosymbionts. Infection with endosymbionts seems to affect several cellular functions of the host such as immune pathways, oxidative stress regulation and autophagy. Our current knowledge about specific host factors leading to endosymbiont tolerance and/or control is still scarce and is based on very few associations between insect hosts and bacteria only. Camponotus floridanus ants harbour the obligate intracellular bacterium Blochmannia floridanus within specialized midgut cells called bacteriocytes. The number of Blochmannia endosymbionts within the midgut tissue increases strongly during host development and reaches a maximum at the late pupal stage, where the entire midgut is transformed into a symbiotic organ. After eclosion of workers the number of Blochmannia strongly decreases again. We chose 15 candidate genes from C. floridanus likely to be involved in host–symbiont interactions based on their significant homology to previously investigated symbiosis-relevant genes from other insects. We determined the expression of these genes in the endosymbiont-bearing midgut tissue in comparison to the residual body tissue at different developmental stages of C. floridanus in order to reveal changes in gene expression correlating with changes in endosymbiont number per host. Strikingly, two pattern recognition receptors (amidase PGRP-LB and PGRP-SC2) were highly expressed in the midgut tissue at the pupal stage, potentially down-modulating the IMD pathway to enable endosymbiont tolerance. Moreover, we investigated the immune gene expression in response to bacterial challenge at the pupal stage. Results showed that the midgut tissue differs in expression pattern in contrast to the residual body. Our results support a key role for amidase PGRPs, especially PGRP-LB, in regulation of the immune response towards endosymbionts in C. floridanus and suggest an involvement of the lysosomal system in control of Blochmannia endosymbionts.