Figure 3.

Southern hybridization analysis of cytosine methylation at bulk 180CEN repeats in sperm and vegetative nuclei of wild-type (Col-0) mature pollen. A subclass of 180CEN repeats contains one MspI/HpaII (CCGG) site and two CviAII/NlaIII (CATG) sites. Genomic DNA (30 ng) extracted from sorted SN or VN was digested using MspI, HpaII, CviAII or NlaIII, separated by gel electrophoresis and probed with 180CEN DNA. MspI and HpaII both cut CCGG but differ in that MspI is inhibited by methylation of outer C, whereas HpaII is inhibited by methylation of inner C. CviAII and NlaIII both cut CATG, but differ in that only NlaIII is inhibited by methylation. SN, sperm nuclei; VN, vegetative nuclei.