Little is known about the composition and organization of the I. scapularis genome. The genome is large in comparison to other sequenced arthropod genomes. Ullmann et al., (2005) estimated the I. scapularis genome is approximately 2.15 Gbp (2.1 x 109 bp) by re-association kinetics. This estimate has been supported by both flow cytometry (Geraci et al., 2007) and genome sequencing. For comparison, the genome of Anopheles gambiae (malaria vector mosquito) is an estimated 278 Mbp (2.78 x 108 bp). The Ixodes genome is reportedly comprised of ~ 40% moderately and ~ 30% highly repetitive DNA (Ullmann et al., 2005).
The JCVI and VectorBase are predicting a set of Ixodes gene models based on the i3 assembly. Community scientists will be asked to help improve gene annotations and to analyze the coding and non-coding portions of the genome. Fluorescence in situ hybridization (FISH) mapping techniques are being developed so that assembled sequence can be ordered and oriented on the 14 Ixodes chromosomes. FISH mapping is also being used to understand the organization of repetitive DNA in the genome.
Geraci, N.S., Johnston, J.S., Robinson, J.P., Wikel, S.K. and Hill, C.A. (2007). Variation in genome size of argasid and ixodid ticks. Insect. Biochem. Mol. Biol. 37, 399-408.
Ullmann, A.J., Lima, C.M.R., Guerrero, F.D., Piesman, J. and Black, W.C. (IV). (2005). Genome size and organization in the black-legged tick, Ixodes scapularis and the southern cattle tick, Boophilus microplus. Insect Mol. Biol. 14, 217-222.