title: Scrutinizing the immune defence inventory of Camponotus floridanus applying total transcriptome sequencing.
abstract: BACKGROUND
  Defence mechanisms of organisms are shaped by their lifestyle, environment and pathogen pressure. Carpenter ants are social insects which live in huge colonies comprising genetically closely related individuals in high densities within nests. This lifestyle potentially facilitates the rapid spread of pathogens between individuals. In concert with their innate immune system, social insects may apply external immune defences to manipulate the microbial community among individuals and within nests. Additionally, carpenter ants carry a mutualistic intracellular and obligate endosymbiotic bacterium, possibly maintained and regulated by the innate immune system. Thus, different selective forces could shape internal immune defences of Camponotus floridanus.
  
  
  RESULTS
  The immune gene repertoire of C. floridanus was investigated by re-evaluating its genome sequence combined with a full transcriptome analysis of immune challenged and control animals using Illumina sequencing. The genome was re-annotated by mapping transcriptome reads and masking repeats. A total of 978 protein sequences were characterised further by annotating functional domains, leading to a change in their original annotation regarding function and domain composition in about 8% of all proteins. Based on homology analysis with key components of major immune pathways of insects, the C. floridanus immune-related genes were compared to those of Drosophila melanogaster, Apis mellifera, and other hymenoptera. This analysis revealed that overall the immune system of carpenter ants comprises many components found in these insects. In addition, several C. floridanus specific genes of yet unknown functions but which are strongly induced after immune challenge were discovered. In contrast to solitary insects like Drosophila or the hymenopteran Nasonia vitripennis, the number of genes encoding pattern recognition receptors specific for bacterial peptidoglycan (PGN) and a variety of known antimicrobial peptide (AMP) genes is lower in C. floridanus. The comparative analysis of gene expression post immune-challenge in different developmental stages of C. floridanus suggests a stronger induction of immune gene expression in larvae in comparison to adults.
  
  
  CONCLUSIONS
  The comparison of the immune system of C. floridanus with that of other insects revealed the presence of a broad immune repertoire. However, the relatively low number of PGN recognition proteins and AMPs, the identification of Camponotus specific putative immune genes, and stage specific differences in immune gene regulation reflects Camponotus specific evolution including adaptations to its lifestyle.
authors.affiliation: Department of Bioinformatics, Biocentre, University of Würzburg, Am Hubland, D-97074, Würzburg, Germany. shishir.bioinfo@gmail.com.|Department of Microbiology, Biocentre, University of Würzburg, Am Hubland, D-97074, Würzburg, Germany. shishir.bioinfo@gmail.com.
authors.forename: Shishir K
authors.initials: SK
authors.lastname: Gupta
authors.affiliation: Department of Microbiology, Biocentre, University of Würzburg, Am Hubland, D-97074, Würzburg, Germany. maria.kupper@uni-wuerzburg.de.
authors.forename: Maria
authors.initials: M
authors.lastname: Kupper
authors.affiliation: Department of Microbiology, Biocentre, University of Würzburg, Am Hubland, D-97074, Würzburg, Germany. carolin.ratzka@googlemail.com.
authors.forename: Carolin
authors.initials: C
authors.lastname: Ratzka
authors.affiliation: Department of Animal Ecology, University of Bayreuth, 95440, Bayreuth, Germany. feldhaar@uni-bayreuth.de.
authors.forename: Heike
authors.initials: H
authors.lastname: Feldhaar
authors.affiliation: Institute of Phytopathology and Applied Zoology, Justus-Liebig University of Giessen, Heinrich-Buff-Ring 26-32, 35392, Giessen, Germany. Andreas.Vilcinskas@agrar.uni-giessen.de.
authors.forename: Andreas
authors.initials: A
authors.lastname: Vilcinskas
authors.affiliation: Department of Microbiology, Biocentre, University of Würzburg, Am Hubland, D-97074, Würzburg, Germany. roy@biozentrum.uni-wuerzburg.de.
authors.forename: Roy
authors.initials: R
authors.lastname: Gross
authors.affiliation: Department of Bioinformatics, Biocentre, University of Würzburg, Am Hubland, D-97074, Würzburg, Germany. dandekar@biozentrum.uni-wuerzburg.de.|EMBL Heidelberg, BioComputing Unit, Meyerhofstraße 1, 69117, Heidelberg, Germany. dandekar@biozentrum.uni-wuerzburg.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Dandekar
authors.affiliation: Department of Bioinformatics, Biocentre, University of Würzburg, Am Hubland, D-97074, Würzburg, Germany. frank.foerster@biozentrum.uni-wuerzburg.de.
authors.forename: Frank
authors.initials: F
authors.lastname: Förster
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001000:Ants / Q000235:genetics / Q000276:immunology*; D004330:Drosophila / Q000235:genetics / Q000276:immunology; D005786:Gene Expression Regulation; D049750:Genome, Insect / Q000276:immunology*; D007113:Immunity, Innate / Q000235:genetics*; D059467:Transcriptome / Q000235:genetics*