Wang Guan-Hong, Niu Li-Ming, Ma Guang-Chang, Xiao Jin-Hua, Huang Da-Wei
Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.
BMC Genomics. 2014 Oct 13;15(1):893. doi: 10.1186/1471-2164-15-893.
Cryptic prophages are genetically defective in their induction and propagation, and are simply regarded as genetic remnants. There are several putative cryptic WO prophages in the sequenced Wolbachia genomes. Whether they are lytic is unclear and their functions are poorly understood. Only three open reading frames (ORFs) in cryptic WO prophages have been reported to be actively transcribed.
In this study, we comprehensively examined the transcription of the only cryptic WO prophage (WOSol) in a Wolbachia strain that infects a fig wasp, Ceratosolen solmsi (Agaonidae, Chalcidoidea). By analyzing the transcriptions of all the ORFs of WOSol in both sexes of C. solmsi, using qualitative and quantitative methods, we demonstrated that i) a high percentage of ORFs are actively transcribed (59%, 17/29); ii) the expression of these ORFs is highly sex-specific, with a strong male bias (three in females and 15 in males); iii) an ank (ankyrin-domain-containing) gene actively transcribed in both wasp sexes is more highly expressed in males.
A large proportion of the genes in the cryptic WO prophage WOSol are expressed, which overturns the concept that cryptic prophages are simply genetically defective. The highly sex-specific expression patterns of these genes in the host suggest that they play important roles in Wolbachia biology and its reproductive manipulation of its insect host, particularly through the males.
隐秘原噬菌体在诱导和增殖方面存在基因缺陷，仅被视为基因残余物。在已测序的沃尔巴克氏体基因组中有几个假定的隐秘WO原噬菌体。它们是否具有裂解性尚不清楚，其功能也了解甚少。据报道，隐秘WO原噬菌体中只有三个开放阅读框（ORF）会被积极转录。
在本研究中，我们全面检测了感染榕小蜂（榕小蜂科，小蜂总科）的沃尔巴克氏体菌株中唯一的隐秘WO原噬菌体（WOSol）的转录情况。通过定性和定量方法分析榕小蜂雌雄两性中WOSol所有ORF的转录情况，我们证明：i）高比例的ORF被积极转录（59%，29个中的17个）；ii）这些ORF的表达具有高度性别特异性，雄性偏好强烈（雌性中有3个，雄性中有15个）；iii）在雌雄两性黄蜂中均积极转录的一个ank（含锚蛋白结构域）基因在雄性中表达水平更高。
隐秘WO原噬菌体WOSol中的大部分基因都有表达，这推翻了隐秘原噬菌体只是简单存在基因缺陷的概念。这些基因在宿主中高度性别特异性的表达模式表明，它们在沃尔巴克氏体生物学及其对昆虫宿主的生殖操纵中发挥重要作用，特别是通过雄性发挥作用。
