Inducible Defenses Stay Up Late: Temporal Patterns of Immune Gene Expression in Tenebrio molitor

G3: Genes, Genomes, Genetics

Jens Rolff¹  Olga Makarova¹  Paul R Johnston¹ 

[1] Evolutionary Biology, Institute for Biology, Free University of Berlin, 14195 Berlin, GermanyEvolutionary Biology, Institute for Biology, Free University of Berlin, 14195 Berlin, GermanyEvolutionary Biology, Institute for Biology, Free University of Berlin, 14195 Berlin, Germany

关键词: RNAseq time course;    costs of immunity;    insect immunity;    persistent infection;    innate immunity;    complex genetics;    tolerance;    complex immunity;    infection;    resistance;   

DOI  :  10.1534/g3.113.008516

学科分类：生物科学（综合）

来源: Genetics Society of America

【 摘 要 】

The course of microbial infection in insects is shaped by a two-stage process of immune defense. Constitutive defenses, such as engulfment and melanization, act immediately and are followed by inducible defenses, archetypically the production of antimicrobial peptides, which eliminate or suppress the remaining microbes. By applying RNAseq across a 7-day time course, we sought to characterize the long-lasting immune response to bacterial challenge in the mealworm beetle Tenebrio molitor, a model for the biochemistry of insect immunity and persistent bacterial infection. By annotating a hybrid de novo assembly of RNAseq data, we were able to identify putative orthologs for the majority of components of the conserved insect immune system. Compared with Tribolium castaneum, the most closely related species with a reference genome sequence and a manually curated immune system annotation, the T. molitor immune gene count was lower, with lineage-specific expansions of genes encoding serine proteases and their countervailing inhibitors accounting for the majority of the deficit. Quantitative mapping of RNAseq reads to the reference assembly showed that expression of genes with predicted functions in cellular immunity, wound healing, melanization, and the production of reactive oxygen species was transiently induced immediately after immune challenge. In contrast, expression of genes encoding antimicrobial peptides or components of the Toll signaling pathway and iron sequestration response remained elevated for at least 7 days. Numerous genes involved in metabolism and nutrient storage were repressed, indicating a possible cost of immune induction. Strikingly, the expression of almost all antibacterial peptides followed the same pattern of long-lasting induction, regardless of their spectra of activity, signaling possible interactive roles in vivo.

【 授权许可】

Unknown