Publication: The study of the transformer gene from Bactrocera dorsalis and B. correcta with putative core promoter regions
Issued Date
2016
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eng
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Mahidol University
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BioMed Central
Bibliographic Citation
BMC Genetics. Vol. 17, (2016), 34
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Kamoltip Laohakieat, Nidchaya Aketarawong, Siriwan Isasawin, Siripong Thitamadee, Sujinda Thanaphum The study of the transformer gene from Bactrocera dorsalis and B. correcta with putative core promoter regions. BMC Genetics. Vol. 17, (2016), 34. doi:10.1186/s12863-016-0342-0 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/2740
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Title
The study of the transformer gene from Bactrocera dorsalis and B. correcta with putative core promoter regions
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Abstract
Background: The transformer (tra) is a sex determining switch in different orders of insects, including Diptera, as in
the family Tephritidae. The lifelong autoregulatory loop of tra female-specific splicing can be reset by the
intervention of male-specific primary signals (M factor). In early development, the functional female and truncated
male TRA proteins relay the sexual fates to the alternative splicing of a bisexual switch gene, doublesex (dsx)
cascading the sexual differentiation processes. Bactrocera dorsalis (Hendel) and Bactrocera correcta (Bezzi) are among
the Bactrocera model worldwide key pests. Area-wide integrated pest management using the male-only Sterile
Insect Technique (SIT) relying on genetic sexing systems is effective in control programs. We undertook the
molecular characterization and comparative studies of the tra orthologues in the Bactrocera species, including the
Salaya1 genetic sexing strain (GSS).
Results: RT-PCR revealed that B. dorsalis tra (Bdtra) and B. correcta tra (Bctra) transcripts contained conservation of
both constitutive exons and male-specific exons as in other Bactrocera. However, new Bdtra male-specific exons
were retained, diversifying the pattern of the male-specifically spliced transcripts. The coding sequences of tra were
highly conserved in Bactrocera (86–95 %) but less so among related genera (61–65 %) within the same Tephritidae
family. A conservation of deduced amino acid sequences (18 residues), called the TEP region, was identified to be
distinctive among tephritids. The 5’ regulatory sequence containing many structural characteristics of the putative
core promoter was discovered in B. correcta. The expression patterns of Bdtra and Bctra were sex-specifically spliced
and the signals relayed to the dsx genes in the adult wild-types. However, the coexistence of male- and femalespecifically
spliced transcripts (980 and 626 bp, respectively) of the B. dorsalis wild-type strain was found in the
Salaya1 GSS adult males. The Bdtra RNA interference masculinized the XX karyotype females into pseudomales, but
their testes were mostly not well developed.
Conclusions: Bdtra and Bctra have sex-specific splicing, similar to Bactroceras, Ceratitis capitata (Wiedemann), and
Anastrephas. A newly identified TEP region is proposed in tephritids. A putative core promoter has been discovered
in Bctra.