Evaluation and Standardization of RNA Extractions with Quality for RNA-Seq for <i>Balamuthia mandrillaris</i>

Abstract

Balamuthia mandrillaris is a free-living amoeba (FLA) that causes granulomatous amebic encephalitis (GAE) and skin lesions. Transcriptomic analysis is a powerful tool used to study B. mandrillaris pathogenic infections. However, preliminary tests of RNA extraction showed poor results, so it has become essential to standardize a protocol for high-quality RNA. The present study evaluated 11 RNA extraction protocols based on three commercial kits by making modifications to the temperature and centrifugation times, and by combining kits. Four protocols, namely Q3 (based on QIAGEN RNeasy Mini Kit, with modifications in temperature and centrifugation times), T1 (Invitrogen TRIzol Reagent), T2 (combination of TRIzol and QIAGEN modified protocols) and T3 (combination of TRIzol and PROMEGA SV Total RNA Isolation protocols), presented RNA with good integrity and purity, except for the T1 protocol, which obtained an A260/230 value below the acceptable threshold. High RNA integrity (RIN) values were obtained with the Q3 (9.8), T2 (9.2), and T3 (8.9) protocols, while the T1 protocol obtained a lower RIN value (7.1). The Q3, T2, and T3 protocols obtained high-quality RNA from B. mandrillaris based on the criteria of integrity, purity, and concentration, where the implemented modifications and combinations raised the quality; thus, their use is recommended to obtain accurate results when performing transcriptomic analysis.

Keywords

• <i>Balamuthia mandrillaris</i>
• RNA extraction
• free-living amoeba
• RNA integrity number
• transcriptomics