title: Transcriptome response to elevated atmospheric CO2concentration in the Formosan subterranean termite,Coptotermes formosanusShiraki (Isoptera: Rhinotermitidae).
abstract: BACKGROUND
  Carbon dioxide (CO2) is a pervasive chemical stimulus that plays a critical role in insect life, eliciting behavioral and physiological responses across different species. High CO2concentration is a major feature of termite nests, which may be used as a cue for locating their nests. Termites also survive under an elevated CO2concentration. However, the mechanism by which elevated CO2concentration influences gene expression in termites is poorly understood.
  
  
  METHODS
  To gain a better understanding of the molecular basis involved in the adaptation to CO2concentration, a transcriptome ofCoptotermes formosanusShiraki was constructed to assemble the reference genes, followed by comparative transcriptomic analyses across different CO2concentration (0.04%, 0.4%, 4% and 40%) treatments.
  
  
  RESULTS
  (1) Based on a high throughput sequencing platform, we obtained approximately 20 GB of clean data and revealed 189,421 unigenes, with a mean length and an N50 length of 629 bp and 974 bp, respectively. (2) The transcriptomic response ofC. formosanusto elevated CO2levels presented discontinuous changes. Comparative analysis of the transcriptomes revealed 2,936 genes regulated among 0.04%, 0.4%, 4% and 40% CO2concentration treatments, 909 genes derived from termites and 2,027 from gut symbionts. Genes derived from termites appears selectively activated under 4% CO2level. In 40% CO2level, most of the down-regulated genes were derived from symbionts. (3) Through similarity searches to data from other species, a number of protein sequences putatively involved in chemosensory reception were identified and characterized inC. formosanus, including odorant receptors, gustatory receptors, ionotropic receptors, odorant binding proteins, and chemosensory proteins.
  
  
  CONCLUSIONS
  We found that most genes associated with carbohydrate metabolism, energy metabolism, and genetic information processing were regulated under different CO2concentrations. Results suggested that termites adapt to ∼4% CO2level and their gut symbionts may be killed under high CO2level. We anticipate that our findings provide insights into the transcriptome dynamics of CO2responses in termites and form the basis to gain a better understanding of regulatory networks.
authors.affiliation: Guangdong Key Laboratory of Integrated Pest Management in Agriculture, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Guangdong Institute of Applied Biological Resources , Guangzhou , Guangdong , China.
authors.forename: Wenjing
authors.initials: W
authors.lastname: Wu
authors.affiliation: Guangdong Key Laboratory of Integrated Pest Management in Agriculture, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Guangdong Institute of Applied Biological Resources , Guangzhou , Guangdong , China.
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Li
authors.affiliation: Guangdong Key Laboratory of Integrated Pest Management in Agriculture, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Guangdong Institute of Applied Biological Resources , Guangzhou , Guangdong , China.
authors.forename: Shijun
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Guangdong Key Laboratory of Integrated Pest Management in Agriculture, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Guangdong Institute of Applied Biological Resources , Guangzhou , Guangdong , China.
authors.forename: Yunling
authors.initials: Y
authors.lastname: Ke
authors.affiliation: Guangdong Key Laboratory of Integrated Pest Management in Agriculture, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Guangdong Institute of Applied Biological Resources, Guangzhou, Guangdong, China; College of Forestry, Northeast Forestry University, Harbin, Heilongjiang, China.
authors.forename: Yahui
authors.initials: Y
authors.lastname: Hou
keywords: Carbon dioxide response; Chemosensory receptor; Coptotermes formosanus; Gene expression; Next generation sequencing data; Transcriptome