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Analysis of four achaete-scute homologs in Bombyx mori reveals new viewpoints of the evolution and functions of this gene family.

Zhou Q, Zhang T, Xu W, Yu L, Yi Y, Zhang Z - BMC Genet. (2008)

Bottom Line: Functions besides neural development controlling have also been found in Drosophila AS-C genes.Proteins encoded by them contained the characteristic bHLH domain and the three proneural ones were also found to have the C-terminal conserved motif.AS-C gene duplication in insects occurs after or parallel to, but not before the taxonomic order formation during evolution.

View Article: PubMed Central - HTML - PubMed

Affiliation: The Biotechnology Research Institute, National Engineering of crop germplasm and genetic improvement, Chinese Academy of Agricultural Sciences, Beijing, 100081, China. Qingxiang_Zhou@meei.harvard.edu

ABSTRACT

Background: achaete-scute complexe (AS-C) has been widely studied at genetic, developmental and evolutional levels. Genes of this family encode proteins containing a highly conserved bHLH domain, which take part in the regulation of the development of central nervous system and peripheral nervous system. Many AS-C homologs have been isolated from various vertebrates and invertebrates. Also, AS-C genes are duplicated during the evolution of Diptera. Functions besides neural development controlling have also been found in Drosophila AS-C genes.

Results: We cloned four achaete-scute homologs (ASH) from the lepidopteran model organism Bombyx mori, including three proneural genes and one neural precursor gene. Proteins encoded by them contained the characteristic bHLH domain and the three proneural ones were also found to have the C-terminal conserved motif. These genes regulated promoter activity through the Class A E-boxes in vitro. Though both Bm-ASH and Drosophila AS-C have four members, they are not in one by one corresponding relationships. Results of RT-PCR and real-time PCR showed that Bm-ASH genes were expressed in different larval tissues, and had well-regulated expressional profiles during the development of embryo and wing/wing disc.

Conclusion: There are four achaete-scute homologs in Bombyx mori, the second insect having four AS-C genes so far, and these genes have multiple functions in silkworm life cycle. AS-C gene duplication in insects occurs after or parallel to, but not before the taxonomic order formation during evolution.

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Genomic structure of Bm-ASH genes. The red region stands for the ORF, and the yellow region stands for non-coding regions; gDNA stands for genomic DNA; (+) and (-) show the published genomic sequences [39] being forward or reverse compared with the cDNAs. "?" shows the region unsequenced. The 6 bp in Bm-ASH1 indicates that there is a 6 bp uncoding region in the first exon of the gene just following the coding region, so is the 4 bp in Bm-ASH2. Genomic sequences are all from SilkDB [39]. The name of the genomic DNA fragment in Bm-ASH1 is Scaffold002070, in Bm-ASH2 is Scaffold007910, in Bm-ASH3 is Scaffold013050, and in Bm-ase is Scaffold000880, respectively.
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Figure 3: Genomic structure of Bm-ASH genes. The red region stands for the ORF, and the yellow region stands for non-coding regions; gDNA stands for genomic DNA; (+) and (-) show the published genomic sequences [39] being forward or reverse compared with the cDNAs. "?" shows the region unsequenced. The 6 bp in Bm-ASH1 indicates that there is a 6 bp uncoding region in the first exon of the gene just following the coding region, so is the 4 bp in Bm-ASH2. Genomic sequences are all from SilkDB [39]. The name of the genomic DNA fragment in Bm-ASH1 is Scaffold002070, in Bm-ASH2 is Scaffold007910, in Bm-ASH3 is Scaffold013050, and in Bm-ase is Scaffold000880, respectively.

Mentions: cDNA sequence of each Bombyx ASH gene was used to blast the silkworm knowledgebase [39], and four separate scaffolds were screened out. The total length of the scaffolds is about 122 Kb (but we could not assemble them into one complex with the present data). Analysis results showed that there was an intron outside of the ORF region in Bm-ASH1 and Bm-ASH2, however there was no intron in either Bm-ASH3 or Bm-ase (Fig. 3).


Analysis of four achaete-scute homologs in Bombyx mori reveals new viewpoints of the evolution and functions of this gene family.

Zhou Q, Zhang T, Xu W, Yu L, Yi Y, Zhang Z - BMC Genet. (2008)

Genomic structure of Bm-ASH genes. The red region stands for the ORF, and the yellow region stands for non-coding regions; gDNA stands for genomic DNA; (+) and (-) show the published genomic sequences [39] being forward or reverse compared with the cDNAs. "?" shows the region unsequenced. The 6 bp in Bm-ASH1 indicates that there is a 6 bp uncoding region in the first exon of the gene just following the coding region, so is the 4 bp in Bm-ASH2. Genomic sequences are all from SilkDB [39]. The name of the genomic DNA fragment in Bm-ASH1 is Scaffold002070, in Bm-ASH2 is Scaffold007910, in Bm-ASH3 is Scaffold013050, and in Bm-ase is Scaffold000880, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2315653&req=5

Figure 3: Genomic structure of Bm-ASH genes. The red region stands for the ORF, and the yellow region stands for non-coding regions; gDNA stands for genomic DNA; (+) and (-) show the published genomic sequences [39] being forward or reverse compared with the cDNAs. "?" shows the region unsequenced. The 6 bp in Bm-ASH1 indicates that there is a 6 bp uncoding region in the first exon of the gene just following the coding region, so is the 4 bp in Bm-ASH2. Genomic sequences are all from SilkDB [39]. The name of the genomic DNA fragment in Bm-ASH1 is Scaffold002070, in Bm-ASH2 is Scaffold007910, in Bm-ASH3 is Scaffold013050, and in Bm-ase is Scaffold000880, respectively.
Mentions: cDNA sequence of each Bombyx ASH gene was used to blast the silkworm knowledgebase [39], and four separate scaffolds were screened out. The total length of the scaffolds is about 122 Kb (but we could not assemble them into one complex with the present data). Analysis results showed that there was an intron outside of the ORF region in Bm-ASH1 and Bm-ASH2, however there was no intron in either Bm-ASH3 or Bm-ase (Fig. 3).

Bottom Line: Functions besides neural development controlling have also been found in Drosophila AS-C genes.Proteins encoded by them contained the characteristic bHLH domain and the three proneural ones were also found to have the C-terminal conserved motif.AS-C gene duplication in insects occurs after or parallel to, but not before the taxonomic order formation during evolution.

View Article: PubMed Central - HTML - PubMed

Affiliation: The Biotechnology Research Institute, National Engineering of crop germplasm and genetic improvement, Chinese Academy of Agricultural Sciences, Beijing, 100081, China. Qingxiang_Zhou@meei.harvard.edu

ABSTRACT

Background: achaete-scute complexe (AS-C) has been widely studied at genetic, developmental and evolutional levels. Genes of this family encode proteins containing a highly conserved bHLH domain, which take part in the regulation of the development of central nervous system and peripheral nervous system. Many AS-C homologs have been isolated from various vertebrates and invertebrates. Also, AS-C genes are duplicated during the evolution of Diptera. Functions besides neural development controlling have also been found in Drosophila AS-C genes.

Results: We cloned four achaete-scute homologs (ASH) from the lepidopteran model organism Bombyx mori, including three proneural genes and one neural precursor gene. Proteins encoded by them contained the characteristic bHLH domain and the three proneural ones were also found to have the C-terminal conserved motif. These genes regulated promoter activity through the Class A E-boxes in vitro. Though both Bm-ASH and Drosophila AS-C have four members, they are not in one by one corresponding relationships. Results of RT-PCR and real-time PCR showed that Bm-ASH genes were expressed in different larval tissues, and had well-regulated expressional profiles during the development of embryo and wing/wing disc.

Conclusion: There are four achaete-scute homologs in Bombyx mori, the second insect having four AS-C genes so far, and these genes have multiple functions in silkworm life cycle. AS-C gene duplication in insects occurs after or parallel to, but not before the taxonomic order formation during evolution.

Show MeSH