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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.

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Multiple alignment of the insect SRs. This is the CLUSTALX alignment employed for the phylogenetic analysis in Figure 3, except that positions of uncertain alignment and large gaps, specifically alignment positions 1–82, 150–160, 209–219, 340–355, 405–435, and 531–559, were excluded from the phylogenetic analysis. The Xs at the start of some sequences were added to facilitate splitting the figure into six convenient parts. Alignment positions are shown at the bottom, along with the "conservation" histogram from CLUSTALX. The predicted TM domains are evident as vertical bands of hydrophobic amino acids shaded blue, and the "pre-peak" is approximately alignment positions 84–103, TM1 is 121–142, TM2 is 161–189, TM3 is 224–234, TM4 is 291–314, TM5 is 378–398, TM6 is 438–457, and TM7 is 511–529.
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Figure 7: Multiple alignment of the insect SRs. This is the CLUSTALX alignment employed for the phylogenetic analysis in Figure 3, except that positions of uncertain alignment and large gaps, specifically alignment positions 1–82, 150–160, 209–219, 340–355, 405–435, and 531–559, were excluded from the phylogenetic analysis. The Xs at the start of some sequences were added to facilitate splitting the figure into six convenient parts. Alignment positions are shown at the bottom, along with the "conservation" histogram from CLUSTALX. The predicted TM domains are evident as vertical bands of hydrophobic amino acids shaded blue, and the "pre-peak" is approximately alignment positions 84–103, TM1 is 121–142, TM2 is 161–189, TM3 is 224–234, TM4 is 291–314, TM5 is 378–398, TM6 is 438–457, and TM7 is 511–529.

Mentions: Phylogenetic relationships of eight SRs in 12 Drosophila species. This is a corrected distance tree based on aligned amino acids and rooted at the midpoint. The variable length and sequence N-termini upstream of the conserved "pre-peak" region (Figures 7, 8, 9, 10, 11, 12 and 13) were removed from the alignment. Species names are abbreviated to the genus plus the first three letters of the species name, and are color-coded. The eight proteins are indicated on the right. Bootstrap support from 1000 replications of uncorrected distance analysis is shown for the major branches. Most orthologous relationships are in accordance with the known species relationships, or near enough, and bootstrap support is not shown for them. Intron losses are shown in lower case light blue letters above the branches to which they map, but only if not shown in Figure 3.


Evolution of the sugar receptors in insects.

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

Multiple alignment of the insect SRs. This is the CLUSTALX alignment employed for the phylogenetic analysis in Figure 3, except that positions of uncertain alignment and large gaps, specifically alignment positions 1–82, 150–160, 209–219, 340–355, 405–435, and 531–559, were excluded from the phylogenetic analysis. The Xs at the start of some sequences were added to facilitate splitting the figure into six convenient parts. Alignment positions are shown at the bottom, along with the "conservation" histogram from CLUSTALX. The predicted TM domains are evident as vertical bands of hydrophobic amino acids shaded blue, and the "pre-peak" is approximately alignment positions 84–103, TM1 is 121–142, TM2 is 161–189, TM3 is 224–234, TM4 is 291–314, TM5 is 378–398, TM6 is 438–457, and TM7 is 511–529.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 7: Multiple alignment of the insect SRs. This is the CLUSTALX alignment employed for the phylogenetic analysis in Figure 3, except that positions of uncertain alignment and large gaps, specifically alignment positions 1–82, 150–160, 209–219, 340–355, 405–435, and 531–559, were excluded from the phylogenetic analysis. The Xs at the start of some sequences were added to facilitate splitting the figure into six convenient parts. Alignment positions are shown at the bottom, along with the "conservation" histogram from CLUSTALX. The predicted TM domains are evident as vertical bands of hydrophobic amino acids shaded blue, and the "pre-peak" is approximately alignment positions 84–103, TM1 is 121–142, TM2 is 161–189, TM3 is 224–234, TM4 is 291–314, TM5 is 378–398, TM6 is 438–457, and TM7 is 511–529.
Mentions: Phylogenetic relationships of eight SRs in 12 Drosophila species. This is a corrected distance tree based on aligned amino acids and rooted at the midpoint. The variable length and sequence N-termini upstream of the conserved "pre-peak" region (Figures 7, 8, 9, 10, 11, 12 and 13) were removed from the alignment. Species names are abbreviated to the genus plus the first three letters of the species name, and are color-coded. The eight proteins are indicated on the right. Bootstrap support from 1000 replications of uncorrected distance analysis is shown for the major branches. Most orthologous relationships are in accordance with the known species relationships, or near enough, and bootstrap support is not shown for them. Intron losses are shown in lower case light blue letters above the branches to which they map, but only if not shown in Figure 3.

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