Caste-, sex-, and age-dependent expression of immune-related genes in a Japanese subterranean termite, <i>Reticulitermes speratus</i>

<div><p>Insects protect themselves from microbial infections through innate immune responses, including pathogen recognition, phagocytosis, the activation of proteolytic cascades, and the synthesis of antimicrobial peptides. Termites, eusocial insects inhabiting microbe-rich wood, live in closely-related family groups that are susceptible to shared pathogen infections. To resist pathogenic infection, termite families have evolved diverse immune adaptations at both individual and societal levels, and a strategy of trade-offs between reproduction and immunity has been suggested. Although termite immune-inducible genes have been identified, few studies have investigated the differential expression of these genes between reproductive and neuter castes, and between sexes in each caste. In this study, we compared the expression levels of immune-related genes among castes, sexes, and ages in a Japanese subterranean termite, <i>Reticulitermes speratus</i>. Using RNA-seq, we found 197 immune-related genes, including 40 pattern recognition proteins, 97 signalling proteins, 60 effectors. Among these genes, 174 showed differential expression among castes. Comparing expression levels between males and females in each caste, we found sexually dimorphic expression of immune-related genes not only in reproductive castes, but also in neuter castes. Moreover, we identified age-related differential expression of 162 genes in male and/or female reproductives. In addition, although <i>R</i>. <i>speratus</i> is known to use the antibacterial peptide C-type lysozyme as an egg recognition pheromone, we determined that <i>R</i>. <i>speratus</i> has not only C-type, but also P-type and I-type lysozymes, as well as other termite species. Our transcriptomic analyses revealed immune response plasticity among all castes, and sex-biased expression of immune genes even in neuter castes, suggesting a sexual division of labor in the immune system of <i>R</i>. <i>speratus</i>. This study heightens the understanding of the evolution of antimicrobial strategies in eusocial insects, and of sexual roles in insect societies as a whole.</p></div

Electronic supplemental information from Multi-functional roles of a soldier-specific volatile as a worker arrestant, primer pheromone and an antimicrobial agent in a termite

Supplementary figure

Electronic supplemental information from Multi-functional roles of a soldier-specific volatile as a worker arrestant, primer pheromone and an antimicrobial agent in a termite

Supplementary figure

Differential expression of serine proteases among castes.

<p>The heatmap indicates the differential expression of 70 serine protease transcripts among castes. Abbreviations are as indicated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0175417#pone.0175417.g001" target="_blank">Fig 1</a>. Relative expression level indicates the mean normalized CPM, ranging from black (scaled expression of 0) to white (scaled expression of 3.0). The tree at the left corresponds to hierarchical clustering of cluster-averaged expression.</p

Differential expression of lysozymes among castes.

<p>The heatmap indicates the differential expression of 9 lysozyme transcripts among castes. Abbreviations are as indicated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0175417#pone.0175417.g001" target="_blank">Fig 1</a>. Relative expression level indicates the mean normalized CPM, ranging from black (scaled expression of 0) to white (scaled expression of 2.75). The tree at the left corresponds to hierarchical clustering of cluster-averaged expression.</p

Differential expressions of CTLDs, GNBPs and PGRPs among castes.

<p>These heatmaps indicate the differential expression of 29 genes belonging to the CTLD superfamily, the GNBP family and PGRPs among termite castes (PQ: primary queen, PK: primary king, SQ: secondary queen). Relative expression level indicates the mean normalized count per million (CPM), ranging from black (scaled expression of 0) to white (scaled expression of 2.5). The tree at the left corresponds to hierarchical clustering of cluster-averaged expression. Numbers in parentheses after caste names refer to the numbers of biological replicates. Ten individuals were pooled for each sex of worker and soldier to obtain sufficient amounts of RNA, while single individuals were used for RNA extraction in the other castes. CTL: C-type lectin-like domain protein, LPSBP: lipopolysaccharide-binding protein, GNBP: Gram-negative binding protein, PGRP: peptidoglycan recognition protein.</p

Number of caste-, sex-, and age-specific immune-related genes.

<p>Number of caste-, sex-, and age-specific immune-related genes.</p

Differential expression of cathepsins among castes.

<p>The heatmap indicates the differential expression of 10 cathepsin transcripts among castes. Abbreviations are as indicated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0175417#pone.0175417.g001" target="_blank">Fig 1</a>. Relative expression level indicates the mean normalized CPM, ranging from black (scaled expression of 0) to white (scaled expression of 3.0). The tree at the left corresponds to hierarchical clustering of cluster-averaged expression.</p

Supplementary Materials from Age-based soldier polyethism: old termite soldiers take more risks than young soldiers

Supplementary textS1, S2, S3, Table S1, Figure S1, S2, S

Movie S1 from Age-based soldier polyethism: old termite soldiers take more risks than young soldiers

Royal guard soldiers defending the royal chamber of a large field colony (colony code: MS150719E) Misawa, Aomori prefecture, Japan