Table 1.

The specific 5′ splice site rule for the hth genes in insects.

Exon	Drosophila		Aedes		Anopheles		Bombyx		Tribolium		Apis		Acyrthosiphon
	bps	3′ & 5′ splicing recognition site	bps	3′ & 5′ splicing recognition site	bps	3′ & 5′ splicing recognition site	bps	3′ & 5′ splicing recognition site	bps	3′ & 5′ splicing recognition site	bps	3′ & 5′ splicing recognition site	bps	3′ & 5′ splicing recognition site
E2	281	cag–gtgagt	251	cag–gtaagt	254	cag–gtaagt	173	cag–gtgagt	224	cag–gtgagt	260	cag–gtgagt	283	cag–gtaagt
E3	142	cag–gtaaga	142	cag–gtaagt	142	cag–gtaagt	142	cag–gtatgt	142	cag–gtaagc	142	cag–gtaagc	142	tag–gtaata
E4	51	cag–gtaagt	51	cag–gtaagt	51	cag–gtaagt	51	cag–gtaagt	51	cag–gtaagt	51	cag–gtgagt	51	Tag–gtaagg
E5	51	cag–gtaagt	51	cag–gtaagt	51	tag–gtaagt	51	cag–gtgagt	51	cag–gtaagt	51	cag–gtgagt	51	cag–gtaagt
E6	186	cag–gtgagt	186	cag–gtgagt	186	cag–gtgagt	171	cag–gtgagt	195	cag–gtaagt	192	cag–gtgagt	255	cag–gtgagt
E7	124	cag–gtaagt	127	cag–gtatgt	127	cag–gtgagt	130	cag–gtaaga	124	cag–gtaaat	130	cag–gtaagt	130	cag–gtaagt
E8	3 or 48	cag–gtaagt	3	cag–gtaagt	3	cag–gtgagt	9	cag–gtgtgc	9	cag–gtaagt	0	–	6	cag–gtaagt
E9	96	cag–gtaagt	99	cag–gtaagt	99	cag–gtaagt	99	cag–gtaact	108	cag–gtgagt	108	cag–gtaagt	132	cag–gtaagt
E10	24	cag–gtaagc	0	–	0	–	0	–	0	–	0	–	0	–
E11	149	cag–gtgagt	149	cag–gtgagt	149	cag–gtaagt	152	cag–gtaaga	149	cag–gtaagt	149	cag–gtaagt	152	tag–gtaagc
E12	77	cag–gtgagt	77	cag–gtgagt	77	cag–gtaagt	77	cag–gtaata	77	cag–gtgagt	77	cag–gtaagt	77	cag–gtaagt
E13	59	cag–gtaact	59	cag–gtaata	59	cag–gttagt	59	cag–gtgtgt	59	cag–gtaagt	59	cag–gtaaga	59	cag–gtaagt

The 3′ and 5′ splice recognition sites for the internal exons in the hth gene from diverse insect species: Drosophila melanogaster (Diptera: Drosophilidae), Aedes aegypti (Diptera: Culicidae), Anopheles gambiae (Diptera: Culicidae), Bombyx mori (Lepidoptera), Tribolium castaneum (Coleoptera), Apis mellifera (Hymenoptera) and Acyrthosiphon pisum (Hemiptera). The length of each exon is also listed. The exon boundary of the internal exons in hth can be defined by CAG-exon-GTGAGT or CAG-exon-GTAAGT, which is a specific subset of the 5′ splice site motifs (Yeo and Burge, 2004). The length of exons 3, 4, 5, 12 and 13 are conserved. The other exons vary slightly in length, but the variations are always in-frame. The 24 bp exon 10 of hth is absent in all of the tested non-Drosophila species.