title: Selection of Reference Genes for RT-qPCR Analysis in the Monarch Butterfly, Danaus plexippus (L.), a Migrating Bio-Indicator.
abstract: Reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) is a powerful technique to quantify gene expression. To facilitate gene expression study and obtain accurate results, normalization relative to stably expressed reference genes is crucial. The monarch butterfly, Danaus plexippus (L.), is one of the most recognized insect species for its spectacular annual migration across North America. Besides its great voyages, D. plexippus has drawn attention to its role as a bio-indicator, ranging from genetically modified organisms (GMOs) to natural ecosystems. In this study, nine reference genes from D. plexippus genome were selected as the candidate reference genes. The expression profiles of these candidates under various biotic and abiotic conditions were evaluated using the four readily available computational programs, BestKeeper, Normfinder, geNorm, and ΔCt method, respectively. Moreover, RefFinder, a web-based computational platform integrating the four above mentioned algorisms, provided a comprehensive ranking of the stability of these reference genes. As a result, a suite of reference genes were recommended for each experimental condition. Specifically, elongation factor 1α (EF1A) and ribosomal protein 49 (RP49) were the most stable reference genes, respectively, under biotic (development, tissue, and sex) and abiotic (photoperiod, temperature, and dietary RNAi) conditions. With the recent release of a 273-million base pair draft genome, results from this study allow us to establish a standardized RT-qPCR analysis and lay a foundation for the subsequent genomic and functional genomic research in D. plexippus, a major bio-indicator and an emerging model for migratory animals.
authors.affiliation: Department of Entomology, University of Kentucky, Lexington, Kentucky, United States of America.
authors.forename: Huipeng
authors.initials: H
authors.lastname: Pan
authors.affiliation: Department of Entomology, University of Kentucky, Lexington, Kentucky, United States of America; Department of Entomology, Cornell University, Ithaca, New York, United States of America.
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Yang
authors.affiliation: Corn Insects and Crop Genetics Research Unit and Department of Entomology, Iowa State University, Ames, Iowa, United States of America.
authors.forename: Keith
authors.initials: K
authors.lastname: Bidne
authors.affiliation: Corn Insects and Crop Genetics Research Unit and Department of Entomology, Iowa State University, Ames, Iowa, United States of America.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Hellmich
authors.affiliation: Department of Entomology, University of Nebraska, Lincoln, Nebraska, United States of America.
authors.forename: Blair D
authors.initials: BD
authors.lastname: Siegfried
authors.affiliation: Department of Entomology, University of Kentucky, Lexington, Kentucky, United States of America.
authors.forename: Xuguo
authors.initials: X
authors.lastname: Zhou
mesh_terms: D025041:Animal Migration / Q000502:physiology*; D000818:Animals; D031108:Asclepias / Q000469:parasitology; D015415:Biomarkers / Q000032:analysis; D002080:Butterflies / Q000235:genetics* / Q000469:parasitology; D004279:DNA, Viral / Q000235:genetics*; D017344:Genes, Insect; D007814:Larva / Q000235:genetics / Q000469:parasitology; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods* / Q000592:standards*; D012015:Reference Standards; D012522:Sarcocystis / Q000472:pathogenicity*; D012523:Sarcocystosis / Q000235:genetics / Q000469:parasitology
chemical_list: D015415:Biomarkers; D004279:DNA, Viral