Genome-Wide Analysis of MicroRNAs in Relation to Pupariation in Oriental Fruit Fly.

Qiang Zhang,Guy Smagghe,Jin-Zhi Niu,Er-Hu Chen,Deng Pan,Wei Dou,Jin-Jun Wang

doi:10.3389/fphys.2019.00301

Qiang Zhang, Guy Smagghe + Show 5 more

Open Access

https://doi.org/10.3389/fphys.2019.00301

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Abstract

Insect metamorphosis is a complex process involving drastic morphological and physiological changes. microRNAs (miRNAs) are a class of endogenous small non-coding RNAs that play key roles in regulating various biological processes, including metamorphosis, by post-transcriptional repression of mRNAs. The oriental fruit fly, Bactrocera dorsalis, is one of the most destructive insect pests in many Asian countries and the Pacific Islands. The regulatory role of miRNAs in B. dorsalis metamorphosis is unclear. To better understand the molecular regulatory mechanisms of miRNAs in pupariation, Illumina sequencing of the wandering stage (WS), the late WS and the white puparium stage of B. dorsalis were performed. Two hundred forty-nine miRNAs, including 184 known miRNAs and 65 novel miRNAs, were obtained. Among these miRNAs, 19 miRNAs were differentially expressed in pupariation, and eight miRNAs showed relative high expression levels (>50 TPM), of which five differentially expressed miRNAs (DEMs) had target differentially expressed genes (DEGs) predicted by the expected miRNA–mRNA negative regulation pattern using the Illumina HiSeq data. Four sets of DEMs and their predicted target DEGs were confirmed by qPCR. Of the four miRNAs, two miRNAs were down-regulated: miR-981, which may target pdpc, and Bdo-novel-mir-55, which potentially regulates spsX1, psB/C, and chit3. The other two miRNAs were up-regulated: let-7a-3p, which possibly controls lap, and Bdo-novel-mir-24, which may regulate ipc and sp1/2. This study provides a useful resource to elucidate the regulatory role of miRNAs and understand the molecular mechanisms of metamorphosis.

Highlights

Metamorphosis is an important process, because pupation failure means death, and a complex process involving extensive morphological, biochemical, and cellular changes
Three small RNA library (sRNA) libraries were constructed from the whole body at three developmental stages (WS, LWS, and white puparium stage (WPS)) to understand the miRNA regulation involved in larval metamorphosis
The length distribution of the clean data for all three developmental stages mostly showed one main peak at 22 nt, which is the typical length of mature miRNAs, and another smaller peak at 26–27 nt, corresponding to piRNAlike sequences

Summary

Introduction

Metamorphosis is an important process, because pupation failure means death, and a complex process involving extensive morphological, biochemical, and cellular changes. Juvenile hormone (JH) and 20-hydroxyecdysone (20E) jointly regulate larval– pupal development. While both hormones are present at the larval stages, they have opposing roles in development. The role of JH is to maintain insects at the larval stage, whereas 20E induces metamorphosis. As chitin is a crucial component of the cuticle, insect metamorphosis is largely dependent on chitin degradation and synthesis, which are strictly coordinate and occur almost simultaneously during larval–pupal development (Yao et al, 2010). A series of chitin biosynthesis enzymes (such as chitin synthase) and catabolic pathway enzymes (such as chitinase) control the process of metamorphosis by regulating chitin

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