Ferraro, M., Buglia, G.L., & Predazzi, V. 1998 Analysis of methylcytosine distribution along the chromosomes of Planococcus citri (Homoptera, Coccoidea).. Cytogenetics and Cell Genetics 81(2): p.45, Suppl.

Notes: [Abstract only.] The mealybug Planococcus citri represents a good model system to study the phenomenon of genomic imprinting: in fact, early in the development in embryos who will develop as males the haploid set of chromosomes of paternal origin becomes heterochromatic, and will maintain the heterochromatic state in most of the tissues. Even though the correlation is still controversial, in vertebrates, among the mechanisms playing a role both in the establishment and/or the maintenance of imprinting, DNA methylation at cytosine residues has often been shown to be involved. As coccids are concerned, to our knowledge only four species have been so far examined as for the presence of this DNA modification, with different results reported even about the same species. We decided to investigate the presence of cytosine methylation in Planococcus citri as possibly involved in the imprinting of the paternal set of chromosomes. Namely, we investigated and compared the overall susceptibility of male and female chromosomes to the two isochizomeres HpaII and MspI, currently used to discriminate between methylated and unmethylated DNA. We applied a fluorescence in situ nick translation technique to fixed chromosomes after exposing them for appropriate time to these endonucleases. The possible presence of differences in specific chromosomal regions was also given attention. The results obtained seem to indicate a quite similar distribution of methylated/unmethylated sites along the chromosomes both in male and female cells.