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Nucleotide Distribution Patterns in Insect Genomes

Manoj Pratim Samanta

This work analyzed genome-wide nucleotide distribution patterns in ten insect genomes. Two internal measures were applied: (i) GC variation and (ii) third codon nucleotide preference. Although the genome size and overall GC level did not show any correlation with insect order, the internal measures usually displayed higher levels of consistency. GC variations in genomes of hymenopteran insects, honeybee and wasp, ranked highest among all eukaryotic genomes analyzed by us. Genomes of honeybee and beetle, insects of different orders with similar overall GC levels, showed significant internal differences. Honeybee genome stood out as unusual due to its high GC variation and 'left-handed' gene locations.

Ultraconserved Sequences in the Honeybee Genome - Are GC-rich Regions Preferred?

Manoj Pratim Samanta

Among all insect genomes, honeybee displays one of the most unusual patterns with interspersed long AT and GC-rich segments. Nearly 75% of the protein-coding genes are located in the AT-rich segments of the genome, but the biological significance of the GC-rich regions is not well understood. Based on an observation that the bee miRNAs, actins and tubulins are located in the GC-rich segments, this work investigated whether other highly conserved genomic regions show similar preferences. Sequences ultraconserved between the genomes of honeybee and Nasonia, another hymenopteran insect, were determined. They showed strong preferences towards locating in the GC-rich regions of the bee genome.

Supplementary table 1.