An HpaII/MspI-PCR assay to measure methylation of DNA in Hoplosternum littorale (Callichthyidae, Siluriformes) from a polluted environment in the central Amazon basin

The HpaII/MspI-PCR is a method based on the sensitivity of restriction enzymes to methylation at their cleavage sites, which permits the comparison of the DNA methylation status of different organisms, based on the differential patterns of digestion. Prior to the present study, nothing was known of the methylation profile of specific DNA sequences in Amazonian fish based on enzymes sensitive to methylation. Given this, the present study investigated the methylation profile of the 18S rRNA gene of the armored catfish, Hoplosternum littorale, which inhabits relatively inhospitable environments in the Amazon basin. A differential methylation profile was found in the 18S rRNA sites, indicating that polluted environments may influence the methylation of DNA, and would have evolved in the species, initially, as a defense mechanism against the expression of transposable elements. (C) 2019 Elsevier B.V. All rights reserved.