Characterization of the genome of the mealybug Planococcus lilacinus, a model organism for studying whole-chromosome imprinting and inactivation

• Published in: Genetical Research Vol. 79; no. 2; pp. 111 - 118
• Main Authors: MOHAN, K. NAGA, RAY, PARAMITA, CHANDRA, H. SHARAT
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.04.2002
• Subjects: Animals; Base Sequence; Blotting, Southern; Chromosomes - genetics; Chromosomes - metabolism; Dinucleotide Repeats - genetics; Drosophila melanogaster - genetics; Female; Gene Silencing - physiology; Genes, Insect; Genome; Genomic Imprinting - genetics; Hemiptera - genetics; Male; Microsatellite Repeats; Minisatellite Repeats; Molecular Sequence Data; Planococcus lilacinus; Pseudococcidae; Repetitive Sequences, Nucleic Acid - genetics; Sequence Analysis, DNA; Sequence Homology, Nucleic Acid
• ISSN: 0016-6723; 1469-5073
• DOI: 10.1017/S0016672302005566

The co-occurrence of three chromosome-wide phenomena – imprinting, facultative heterochromatization and diffuse centromere – in the mealybug Planococcus lilacinus makes investigation of the genomics of this species an attractive prospect. In order to estimate the complexity of the genome of this species, 300 random stretches of its DNA, constituting ∼0·1% of the genome, were sequenced. Coding sequences appear to constitute ∼53·5%, repeat sequences ∼44·5% and non-coding single-copy sequences ∼2% of the genome. The proportion of repetitive sequences in the mealybug is higher than that in the fruit fly Drosophila melanogaster (∼30%). The mealybug genome (∼220 Mb) is about 1·3 times the size of the fly genome (∼165 Mb) and its GC content (∼35%) less than that of the fly genome (∼40%). The relative abundance of various dinucleotides, as analysed by the method of Gentles and Karlin, shows that the dinucleotide signatures of the two species are moderately similar and that in the mealybug there is neither over-representation nor under-representation of any dinucleotide.