Temporal Expression Profiles Reveal Potential Targets during Postembryonic Development of Forensically Important Sarcophaga peregrina (Diptera: Sarcophagidae)

SIMPLE SUMMARY: Forensic entomology plays a major role in postmortem interval (PMI) estimation, mainly based on morphological characteristics of larvae colonized on decomposed corpses. However, weight and length cannot be used as relevant parameters to calculate the age of wandering at the larval and pupal stages. In order to identify a specific indicator that may serve as a potential target, studies on the mechanism during postembryonic development may provide a foundation to establish a molecular age determination method. Sarcophaga peregrina (Robineau-Desvoidy, 1830) is a species of medical and forensic importance. In this study, transcriptome analysis was performed to investigate gene expression profiles from the larval to pupal stages of S. peregrina, which were used to identify differentially expressed genetic markers as candidates for molecular age estimation. This study explores molecular mechanisms during postembryonic development of S. peregrina. The developmental, stage-specific gene profiles suggest genetic markers for age prediction of forensically important flies. ABSTRACT: Sarcophaga peregrina (Robineau-Desvoidy, 1830) is a species of medical and forensic importance. In order to investigate the molecular mechanism during postembryonic development and identify specific genes that may serve as potential targets, transcriptome analysis was used to investigate its gene expression dynamics from the larval to pupal stages, based on our previous de novo-assembled genome of S. peregrina. Totals of 2457, 3656, 3764, and 2554 differentially expressed genes were identified. The specific genes encoding the structural constituent of cuticle were significantly differentially expressed, suggesting that degradation and synthesis of cuticle-related proteins might actively occur during metamorphosis. Molting (20-hydroxyecdysone, 20E) and juvenile (JH) hormone pathways were significantly enriched, and gene expression levels changed in a dynamic pattern during the developmental stages. In addition, the genes in the oxidative phosphorylation pathway were significantly expressed at a high level during the larval stage, and down-regulated from the wandering to pupal stages. Weighted gene co-expression correlation network analysis (WGCNA) further demonstrated the potential regulation mechanism of tyrosine metabolism in the process of puparium tanning. Moreover, 10 consistently up-regulated genes were further validated by qRT-PCR. The utility of the models was then examined in a blind study, indicating the ability to predict larval development. The developmental, stage-specific gene profiles suggest novel molecular markers for age prediction of forensically important flies.