Genomic organization of TipE gene family members in 11 insect species and Daphnia pulex. TipE gene family members exhibit well-maintained local gene neighbourhoods across Insecta. Orthologues of Drosophila melanogaster (Dmela) TipE (red), Teh2 (blue), and Teh3 (green) form a conserved synteny block nested in the last intron of CG18675 orthologues (orange), except in the silk moth (Bombyx mori, Bmori) and the four beetle (Tribolium castaneum, Tcast) where they have escaped from intronic nesting. The synteny block is extended by Teh4 orthologues (purple) in all insects except the mosquitoes (Anopheles gambiae, Agamb; Aedes aegypti, Aaegy; and Culex quinquefasciatus, Cquin) and the silk moth. The gene cluster is conserved in fruit flies with the inserted VhaM9.7-c gene in Dmela also present in Drosophila mojavensis (Dmoja) and ten other drosophilids (not shown). Although Teh1 orthologues (cyan) are often not linked to the TipE locus, the neighbouring location in the human body louse (Pediculus humanus, Phuma) is likely to represent the ancestral arrangement, supported by the genomic proximity of Teh1 in the pea aphid (Acyrthosiphon pisum, Apisu) and parasitoid wasp (Nasonia vitripennis, Nvitr). The honey bee (Apis mellifera, Amell) and flour beetle Teh1 orthologues have undergone translocation events relative to their Teh4-Teh2-Teh3-TipE clusters, but are retained on the same linkage groups. The genome of the crustacean water flea, Daphnia pulex (Dpule), encodes orthologues of TipE, Teh1, and Teh2, but only one Teh3/4-like gene (s8g331). As Teh3 is a single-coding-exon gene in all the insect genomes, it likely arose from the retrotransposition of a Teh4-like gene before the insect radiation. Putative orthologous relations among TipE gene family members are indicated with dashed lines. Start and end positions are indicated for scaffolds, supercontigs, linkage groups, or chromosomes with arrows indicating the direction of the forward strand of the reference assemblies. Complete gene models including untranslated regions and alternative transcripts are displayed for Dmela while only coding-sequence regions are depicted for the other species.
Li et al. BMC Evolutionary Biology 2011 11:337 doi:10.1186/1471-2148-11-337