Differential gene expression in Drosophila melanogaster and D. nigrosparsa infected with the same Wolbachia strain

Abstract

Wolbachia are maternally inherited endosymbionts that infect nearly half of all arthropod species. Wolbachia manipulate their hosts to maximize their transmission, but they can also provide benefits such as nutrients and resistance against viruses to their hosts. The Wolbachia strain wMel was recently found to increase locomotor activities and possibly trigger cytoplasmic incompatibility in the transinfected fly Drosophila nigrosparsa. Here, we investigated, in females of both D. melanogaster and D. nigrosparsa, the gene expression between animals uninfected and infected with wMel, using RNA sequencing to see if the two Drosophila species respond to the infection in the same or different ways. A total of 2164 orthologous genes were used. The two fly species responded to the infection in different ways. Significant changes shared by the fly species belong to the expression of genes involved in processes such as oxidation-reduction process, iron-ion binding, and voltage-gated potassium-channel activity. We discuss our findings also in the light of how Wolbachia survive within both the native and the novel host.

Figure 1

(A) Venn diagram of orthologous genes with posterior likelihoods in the fourth quartile of Drosophila melanogaster and Drosophila nigrosparsa. Unique genes and genes shared between species are shown. (B) Non-metric multidimensional scaling (NMDS) plot using Bray–Curtis dissimilarities with square root transformation of the uninfected and infected samples of both species. Stress (standardized residual sum of squares) values of NMDS and R-values of each group comparison calculated from ANOSIM (Rstatus is between uninfected and infected lines, Rline is among lines, and Rspecies is between species) are shown. For each sample, n = 5, except for mu_1 (n = 4).

Figure 2

(A) Gene expressions of Drosophila melanogaster uninfected (mu_0) and infected (mi_1, mi_2, and mi_3) and Drosophila nigrosparsa (B) uninfected (nu_0) and infected (ni_3, ni_6, and ni_8). Genes were clustered using Pearson correlation. Only orthologous genes with posterior likelihoods greater than 0.5 were selected (101 and 85 genes of D. melanogaster and D. nigrosparsa, respectively). The heatmaps were generated using the R package NMF.