Figure 1.

Cellular distribution of 6mA in Tetrahymena. (A) 6mA occurs in vegetative cells with no obvious cell-cycle difference, shown by immunofluorescence staining with the modification-specific antibody. Note the absence of 6mA signal in MIC (arrowheads). Bar = 15 μm. (B) Differential distribution of 6mA in MAC and MIC, revealed by dot blot analysis using a specific anti-6mA antibody. Methylene blue hydrate staining was performed to determine the amount of loaded DNA. (C) 6mA occurs de novo in the newly developed MAC during conjugation. Cell stages are distinguished by nuclear events during conjugation. In the early phase of conjugation (starved, meiosis and zygotic), 6mA only exists in the parental MAC. Along with degradation of the old MAC, 6mA signal gradually builds up in the new MAC (dotted line circles). Bar = 15 μm.