Comparison of different extraction kits to isolate microRNA from Galleria mellonella (wax moth) larvae infected with Metarhizium brunneum (ARSEF4556)

MicroRNAs (miRNAs) play an important role in regulating gene expression and are involved in developmental processes in animals, plants and fungi. To understand the role of miRNAs in a biological system, it is important to optimise the extraction procedures to obtain high quality and quantity nucleic acid that enable high throughput sequencing and expression analysis. Numerous kit-based miRNA extraction protocols have been optimised generally to single cell or tissue cultures. Fungi, however, often occupy physically and chemically complex environments which miRNA make extraction challenging, such as fungal pathogens interacting within plant or animal host tissue. We used a Galleria mellonella (wax moth) larvae and entomopathogenic fungus Metarhizium brunneum ARSEF 4556 host/pathogen model to compare commercially available miRNA extraction kits (Invitrogen PureLink miRNA Isolation Kit, Ambion mirVanamiRNA Isolation Kit and Norgen microRNA purification Kit). Our results showed reproducible and significant differences in miRNAs extraction between the kits, with the Invitrogen PureLink miRNA Isolation protocol demonstrating the best performance in terms of miRNA quantity, quality and integrity isolated from fungus-infected insect tissue.