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DNA methylation is one of the most extensively studied epigenetic modifications of genomic DNA. In recent years, sequencing of bisulfite-converted DNA, particularly via next-generation sequencing technologies, has become a widely popular method to study DNA methylation. This method can be readily applied to a variety of species, dramatically expanding the scope of DNA methylation studies beyond the traditionally studied human and mouse systems. In parallel to the increasing wealth of genomic methylation profiles, many statistical tools have been developed to detect differentially methylated loci (DMLs) or differentially methylated regions (DMRs) between biological conditions. We discuss and summarize several key properties of currently available tools to detect DMLs and DMRs from sequencing of bisulfite-converted DNA. However, the majority of the statistical tools developed for DML/DMR analyses have been validated using only mammalian data sets, and less priority has been placed on the analyses of invertebrate or plant DNA methylation data. We demonstrate that genomic methylation profiles of non-mammalian species are often highly distinct from those of mammalian species using examples of honey bees and humans. We then discuss how such differences in data properties may affect statistical analyses. Based on these differences, we provide three specific recommendations to improve the power and accuracy of DML and DMR analyses of invertebrate data when using currently available statistical tools. These considerations should facilitate systematic and robust analyses of DNA methylation from diverse species, thus advancing our understanding of DNA methylation.

Mast cell granules, obtained from sonically disintegrated rat peritioneal cells and suspended in sucrose, 0.34 M, were found to release histamine in the presence of bee venom. Three venom fractions were obtained by gel filtration; two of these had strong histamine releasing capacity, namely “F I” containing phosphatidase A, and “F III” with direct hemolytic properties. The third fraction, “F II”, which releases histamine from intact mast cells, had little effect on granules. Various possibilities for the release mechanism, namely phosphatidase activity, surface activity, and cation exchange, are discussed.

Radioactive methionine was injected into the thorax of honey bees. After several hours, mitochondrial and supernatant proteins were prepared from thorax and hydrolyzed with pronase. In these digests labelled N-formyl- and N-acetyl-methionine were detected. The latter was about evenly distributed between the two fractions, while the bulk of formyl-methionine was present in mitochondrial protein. Control experiments exclude a bacterial origin of these acyl-methionines.