Performance comparison of commercially available kits for wild birds RNA extraction

RNA extraction demands careful sample handling and processing due to the lack of stability of RNA in the environment. However, these conditions are sometimes challenging to achieve when working with free-ranging animals. The main objective of this study was to evaluate the efficiency of three commercial RNA extraction kits for biological samples obtained from six wild bird species (black-headed gull, griffon vulture, house sparrow, mallard, song thrush, and common starling). We extracted 24 samples (faeces, oropharyngeal swabs, and cloacal swabs) using RNeasy PowerMicrobiome Kit, RNeasy PowerFecal Pro Kit, and RNeasy Mini Kit (Qiagen). The extraction performance was assessed based on total RNA yield, RNA integrity, and purity ratios (260/280 and 260/230). Moreover, an analysis to determine the inhibitory effect of the extracted samples and a multiple linear regression model were performed. RNA extraction performance varied considerably among species, sample types, and extraction kits. Overall, the RNeasy PowerFecal Pro Kit yielded higher RNA integrity and purity values and showed lower quantitative reverse transcription polymerase chain reaction inhibition than the other kits, particularly in faecal samples. Our findings highlight the importance of selecting extraction methods according to both species and sample type when working with wildlife samples.