Small heat shock proteins (sHSPs) are the most diverse but also the most poorly known family of molecular chaperones, and they play essential roles in various biological processes. The striped stem borer, Chilo suppressalis (Insecta: Lepidoptera: Pyralidae), is one of the most serious pests of rice, causing extensive damage and yield loss. In this study, we isolated and characterized five members of the sHSPs family-Cshsp19.8, Cshsp21.4, Cshsp21.5, Cshsp21.7a, and Cshsp21.7b-from C. suppressalis. The cDNAs of these genes encoded proteins of 177, 187, 191, 191, and 191 amino acids with isoelectric points of 7.0, 5.6, 6.1, 6.3, and 6.3, respectively. While Cshsp19.8, Cshsp21.5, and Cshsp21.7b had no introns, Cshsp21.4 and Cshsp21.7a contained one and two introns, respectively. Structural analysis indicated that all five Cshsps possessed conserved arginine and a V/IXI/V motif, which is related to hydrophobic characteristics of sHSPs. The five heat shock proteins can be classified into two main groups: an orthologous type (Cshsp21.4 and Cshsp21.7a) and a species-specific type (Cshsp19.8, Cshsp21.5, and Cshsp21.7b). Real-time quantitative PCR analyses revealed that Cshsp19.8, Cshsp21.5, Cshsp21.7a, and Cshsp21.7b all exhibited their highest expression levels within Malpighian tubules or the hindgut, while such levels were found in the head for Cshsp21.4. The expression of Csshsps at different developmental stages revealed that the mRNA levels of Cshsp19.8, Cshsp21.4, Cshsp21.5, and Cshsp21.7b peaked in adults, whereas the highest level of Cshsp21.7a was observed in first instar larvae. Cshsp19.8 and Cshsp21.7b were both upregulated dramatically by heat and cold, and Cshsp21.5 could be induced by cold stress. Neither Cshsp21.4 nor Cshsp21.7a responded to heat or cold. These results demonstrated that different Csshsps play distinctive roles in the regulation of the physiological activities in C. suppressalis.

Sublethal concentrations of chlorantraniliprole adversely affect the development and reproduction of C. suppressalis. The downregulation of CsVg by chlorantraniliprole might have negative impacts on the fecundity of C. suppressalis. © 2016 Society of Chemical Industry.

The pink stem borer, Sesamia inferens, which is endemic in China and other parts of Asia, is a major pest of rice and causes significant yield loss in this host plant. Very few studies have addressed gene expression in S. inferens. Quantitative real-time PCR (qRT-PCR) is currently the most accurate and sensitive method for gene expression analysis. In qRT-PCR, data are normalized using reference genes, which help control for internal differences and reduce error between samples. In this study, seven candidate reference genes, 18S ribosomal RNA (18S rRNA), elongation factor 1 (EF1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), ribosomal protein S13 (RPS13), ribosomal protein S20 (RPS20), tubulin (TUB), and β-actin (ACTB) were evaluated for their suitability in normalizing gene expression under different experimental conditions. The results indicated that three genes (RPS13, RPS20, and EF1) were optimal for normalizing gene expression in different insect tissues (head, epidermis, fat body, foregut, midgut, hindgut, Malpighian tubules, haemocytes, and salivary glands). 18S rRNA, EF1, and GAPDH were best for normalizing expression with respect to developmental stages and sex (egg masses; first, second, third, fourth, fifth, and sixth instar larvae; male and female pupae; and one-day-old male and female adults). 18S rRNA, RPS20, and TUB were optimal for fifth instars exposed to different temperatures (−8, −6, −4, −2, 0, and 27°C). To validate this recommendation, the expression profile of a target gene heat shock protein 83 gene (hsp83) was investigated, and results showed the selection was necessary and effective. In conclusion, this study describes reference gene sets that can be used to accurately measure gene expression in S. inferens.

Quantitative real-time polymerase chain reaction (qRT-PCR) is a valuable tool for estimating gene expression; however, the validity is largely dependent on the selection of stable reference genes. The suitability of various reference genes for qRT-PCR analysis was evaluated in, Chilo suppressalis (Walker). The ΔCt method, geNorm, NormFinder, and BestKeeper were used to evaluate the suitability of nine candidate reference genes for normalizing gene expression in larval tissues and organs and during high and low temperature stress. The ΔCt method, geNorm, and NormFinder produced similar stability rankings; H3, UBI, and EF1 were the most stable reference genes for monitoring gene expression in larval tissue and organs, and EF1, TUB, and AK were the optimal genes for thermal stress. However, for thermal stress, RPS11 was the most stable gene based on BestKeeper. To validate these recommendations, the expression profile of the gene encoding heat shock protein 60 (Hsp60) was investigated. Hsp60 transcript levels showed significant differences when normalized to the most versus least stable reference genes. These results further confirm the importance of testing reference genes using the selected experimental parameters. The reference genes identified in the present study will improve the quality of gene expression data obtained for C. suppressalis and will facilitate future studies aimed at understanding the biology of this important insect pest.

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Time-Resolved Fluorescence Resonance Energy Transfer (TR-FRET) technology is a widely used immunoassay that enables high-throughput quantitative measurements of proteins of interest. One of the well established examples is the TR-FRET assay for mutant huntingtin protein (HTT), which is the major cause of the neurodegenerative Huntington's disease (HD). To measure the mutant HTT protein, the published assays utilize a polyQ antibody, MW1, paired with HTT N-terminal antibodies. MW1 has much higher apparent affinity to mutant HTT with expanded polyQ stretch than to wild-type HTT with shorter polyQ, and thus the assays detect mutant HTT preferentially. Here we report a reversible temperature dependent change of TR-FRET signals for HTT N-terminal fragments: the signals become higher when the temperature is lowered from room temperature to 4°C. Interestingly, the temperature sensitivity of the TR-FRET signals is much higher for the Q25 (wild-type) than for the Q72 (mutant) protein. We further revealed that it is likely due to a temperature and polyQ length-dependent structural or spatial change of HTT, which is potentially useful for understanding polyQ structure and toxicity.

Liriomyza trifolii is a highly-invasive leafmining insect that causes significant damage to vegetables and horticultural crops worldwide. Relatively few studies have quantified gene expression in L. trifolii using real-time quantitative PCR (RT-qPCR), which is a reliable and sensitive technique for measuring gene expression. RT-qPCR requires the selection of reference genes to normalize gene expression data and control for internal differences between samples. In this study, nine housekeeping genes from L. trifolii were selected for their suitability in normalizing gene expression using geNorm, Normfinder, BestKeeper, the ΔCt method and RefFinder. HSP21.7, which encodes heat shock protein 21.7, was used as a target gene to validate the expression of candidate reference genes. Results indicated that ACTIN and 18S were optimal for developmental stage and low temperature, TUB and 18S showed the most stable expression for sex, and GAPDH and ACTIN were the best reference genes for monitoring gene expression at high temperature. Selection and validation of appropriate reference genes are critical steps in normalizing gene expression levels, which improve the accuracy and quality of expression data. Results of this study provide vital information on reference genes and is valuable in developing a standardized RT-qPCR protocol for functional genomics research in L. trifolii.

Quantitative real time PCR (qRT-PCR) has emerged as a reliable and reproducible technique for studying gene expression analysis. For accurate results, the normalization of data with reference genes is particularly essential. Once the transcriptome sequencing of Frankliniella occidentalis was completed, numerous unigenes were identified and annotated. Unfortunately, there are no studies on the stability of reference genes used in F. occidentalis. In this work, seven candidate reference genes, including actin, 18S rRNA, H3, tubulin, GAPDH, EF-1 and RPL32, were evaluated for their suitability as normalization genes under different experimental conditions using the statistical software programs BestKeeper, geNorm, Normfinder and the comparative ΔCt method. Because the rankings of the reference genes provided by each of the four programs were different, we chose a user-friendly web-based comprehensive tool RefFinder to get the final ranking. The result demonstrated that EF-1 and RPL32 displayed the most stable expression in different developmental stages; RPL32 and GAPDH showed the most stable expression at high temperatures, while 18S and EF-1 exhibited the most stable expression at low temperatures. In this study, we validated the suitable reference genes in F. occidentalis for gene expression profiling under different experimental conditions. The choice of internal standard is very important in the normalization of the target gene expression levels, thus validating and selecting the best genes will help improve the quality of gene expression data of F. occidentalis. What is more, these validated reference genes could serve as the basis for the selection of candidate reference genes in other insects.