Limits...
Evolution of the sugar receptors in insects.

Kent LB, Robertson HM - BMC Evol. Biol. (2009)

Bottom Line: Twelve intron gains and 63 losses are inferred within the SR family.Examination of the SRs in these fly, mosquito, moth, beetle, and hymenopteran genome sequences reveals that they appear to have originated independently from single ancestral genes within the dipteran and coleopteran lineages, and two genes in the lepidopteran and hymenopteran lineages.The origin of the insect SRs will eventually be illuminated by additional basal insect and arthropod genome sequences.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Entomology, University of Illinois at Urbana-Champaign, 61801, USA. lkent@life.uiuc.edu

ABSTRACT

Background: Perception of sugars is an invaluable ability for insects which often derive quickly accessible energy from these molecules. A distinctive subfamily of eight proteins within the gustatory receptor (Gr) family has been identified as sugar receptors (SRs) in Drosophila melanogaster (Gr5a, Gr61a, and Gr64a-f). We examined the evolution of these SRs within the 12 available Drosophila genome sequences, as well as three mosquito, two moth, and beetle, bee, and wasp genome sequences.

Results: While most Drosophila species retain all eight genes, we find that the three Drosophila subgenus species have lost Gr64d, while D. grimshawi and the D. pseudoobscura/persimilis sibling species have also lost Gr5a function. The entire Gr64 gene complex was also duplicated in the D. grimshawi lineage, but only one potentially functional copy of each gene has been retained. The numbers of SRs range from two in the hymenopterans Apis mellifera and Nasonia vitripennis to 16 in the beetle Tribolium castaneum. An unusual aspect is the evolution of a novel exon from intronic sequence in an expanded set of four SRs in Bombyx mori (BmGr5-8), which appears to be the first example of such exonization in insects. Twelve intron gains and 63 losses are inferred within the SR family.

Conclusion: Examination of the SRs in these fly, mosquito, moth, beetle, and hymenopteran genome sequences reveals that they appear to have originated independently from single ancestral genes within the dipteran and coleopteran lineages, and two genes in the lepidopteran and hymenopteran lineages. The origin of the insect SRs will eventually be illuminated by additional basal insect and arthropod genome sequences.

Show MeSH

Related in: MedlinePlus

Intron locations and phases in the insect SR genes. Introns are named in an alphabetical series from 5' to 3' ends of the genes, positioned above a line representing a 450aa SR, with the longer N-terminus typical of the DmGr5a and 64e/f lineage. Hence the coordinates of the introns are ~20 aa later than those shown in Figure 4 of Robertson et al. [5]. Correspondence between intron names in Robertson et al. [5] and those herein is: a/a, b/b, d/f, j/h, o/j, r/m, y/o, a'/p, 2/r, 3/s. Intron phase is shown below the line (0 is between codons, 1 is after the first codon position, and 2 after the second codon position).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2667405&req=5

Figure 6: Intron locations and phases in the insect SR genes. Introns are named in an alphabetical series from 5' to 3' ends of the genes, positioned above a line representing a 450aa SR, with the longer N-terminus typical of the DmGr5a and 64e/f lineage. Hence the coordinates of the introns are ~20 aa later than those shown in Figure 4 of Robertson et al. [5]. Correspondence between intron names in Robertson et al. [5] and those herein is: a/a, b/b, d/f, j/h, o/j, r/m, y/o, a'/p, 2/r, 3/s. Intron phase is shown below the line (0 is between codons, 1 is after the first codon position, and 2 after the second codon position).

Mentions: A novel exon in BmGr5-8. The amino acids of the TM5 and TM6 regions encoded by the ends of the exons flanking the novel exon are shown aligned with each other for the seven moth SRs. Amino acids shared by at least six of the sequences are highlighted in bold font. Like other SRs, BmGr4 does not have the novel exon, and the same is predicted for HvCr1. The location of the phase 2 intron in BmGr4 (intron p in Figure 6) is shown. BmGr5-8 have a short novel exon encoding 15–20 unconserved amino acids, and an additional flanking phase 2 intron (intron q in Figure 6). HvCr5 is predicted to have an intron q, however the precise location cannot be predicted.


Evolution of the sugar receptors in insects.

Kent LB, Robertson HM - BMC Evol. Biol. (2009)

Intron locations and phases in the insect SR genes. Introns are named in an alphabetical series from 5' to 3' ends of the genes, positioned above a line representing a 450aa SR, with the longer N-terminus typical of the DmGr5a and 64e/f lineage. Hence the coordinates of the introns are ~20 aa later than those shown in Figure 4 of Robertson et al. [5]. Correspondence between intron names in Robertson et al. [5] and those herein is: a/a, b/b, d/f, j/h, o/j, r/m, y/o, a'/p, 2/r, 3/s. Intron phase is shown below the line (0 is between codons, 1 is after the first codon position, and 2 after the second codon position).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2667405&req=5

Figure 6: Intron locations and phases in the insect SR genes. Introns are named in an alphabetical series from 5' to 3' ends of the genes, positioned above a line representing a 450aa SR, with the longer N-terminus typical of the DmGr5a and 64e/f lineage. Hence the coordinates of the introns are ~20 aa later than those shown in Figure 4 of Robertson et al. [5]. Correspondence between intron names in Robertson et al. [5] and those herein is: a/a, b/b, d/f, j/h, o/j, r/m, y/o, a'/p, 2/r, 3/s. Intron phase is shown below the line (0 is between codons, 1 is after the first codon position, and 2 after the second codon position).
Mentions: A novel exon in BmGr5-8. The amino acids of the TM5 and TM6 regions encoded by the ends of the exons flanking the novel exon are shown aligned with each other for the seven moth SRs. Amino acids shared by at least six of the sequences are highlighted in bold font. Like other SRs, BmGr4 does not have the novel exon, and the same is predicted for HvCr1. The location of the phase 2 intron in BmGr4 (intron p in Figure 6) is shown. BmGr5-8 have a short novel exon encoding 15–20 unconserved amino acids, and an additional flanking phase 2 intron (intron q in Figure 6). HvCr5 is predicted to have an intron q, however the precise location cannot be predicted.

Bottom Line: Twelve intron gains and 63 losses are inferred within the SR family.Examination of the SRs in these fly, mosquito, moth, beetle, and hymenopteran genome sequences reveals that they appear to have originated independently from single ancestral genes within the dipteran and coleopteran lineages, and two genes in the lepidopteran and hymenopteran lineages.The origin of the insect SRs will eventually be illuminated by additional basal insect and arthropod genome sequences.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Entomology, University of Illinois at Urbana-Champaign, 61801, USA. lkent@life.uiuc.edu

ABSTRACT

Background: Perception of sugars is an invaluable ability for insects which often derive quickly accessible energy from these molecules. A distinctive subfamily of eight proteins within the gustatory receptor (Gr) family has been identified as sugar receptors (SRs) in Drosophila melanogaster (Gr5a, Gr61a, and Gr64a-f). We examined the evolution of these SRs within the 12 available Drosophila genome sequences, as well as three mosquito, two moth, and beetle, bee, and wasp genome sequences.

Results: While most Drosophila species retain all eight genes, we find that the three Drosophila subgenus species have lost Gr64d, while D. grimshawi and the D. pseudoobscura/persimilis sibling species have also lost Gr5a function. The entire Gr64 gene complex was also duplicated in the D. grimshawi lineage, but only one potentially functional copy of each gene has been retained. The numbers of SRs range from two in the hymenopterans Apis mellifera and Nasonia vitripennis to 16 in the beetle Tribolium castaneum. An unusual aspect is the evolution of a novel exon from intronic sequence in an expanded set of four SRs in Bombyx mori (BmGr5-8), which appears to be the first example of such exonization in insects. Twelve intron gains and 63 losses are inferred within the SR family.

Conclusion: Examination of the SRs in these fly, mosquito, moth, beetle, and hymenopteran genome sequences reveals that they appear to have originated independently from single ancestral genes within the dipteran and coleopteran lineages, and two genes in the lepidopteran and hymenopteran lineages. The origin of the insect SRs will eventually be illuminated by additional basal insect and arthropod genome sequences.

Show MeSH
Related in: MedlinePlus