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Title

The gene transformer-2 of Anastrepha fruit flies (Diptera, Tephritidae) and its evolution in insects

AuthorsSarno, Francesca ; Ruiz, María Fernanda ; Eirín-López, José María; Perondini, André L. P.; Selivon, Denise; Sánchez, Lucas
KeywordsDiptera
Tephritidae
Anastrepha obliqua
Bactrocera oleae
Ceratitis capitata
Sex determination processes
Molecular evolution
Developmental gene expression and regulation
Phylogeny
Double-stranded RNA
Insect ribonucleoproteins
Drosophila spp.
Issue Date13-May-2010
PublisherBioMed Central
CitationBMC Evolutionary Biology, 10:140-153 (2010)
AbstractIn the tephritids Ceratitis, Bactrocera and Anastrepha, the gene transformer provides the memory device for sex determination via its auto-regulation; only in females is functional Tra protein produced. To date, the isolation and characterisation of the gene transformer-2 in the tephritids has only been undertaken in Ceratitis, and it has been shown that its function is required for the female-specific splicing of doublesex and transformer pre-mRNA. It therefore participates in transformer auto-regulatory function. In this work, the characterisation of this gene in eleven tephritid species belonging to the less extensively analysed genus Anastrepha was undertaken in order to throw light on the evolution of transformer-2. [Results]: The gene transformer-2 produces a protein of 249 amino acids in both sexes, which shows the features of the SR protein family. No significant partially spliced mRNA isoform specific to the male germ line was detected, unlike in Drosophila. It is transcribed in both sexes during development and in adult life, in both the soma and germ line. The injection of Anastrepha transformer-2 dsRNA into Anastrepha embryos caused a change in the splicing pattern of the endogenous transformer and doublesex pre-mRNA of XX females from the female to the male mode. Consequently, these XX females were transformed into pseudomales. The comparison of the eleven Anastrepha Transformer-2 proteins among themselves, and with the Transformer-2 proteins of other insects, suggests the existence of negative selection acting at the protein level to maintain Transformer-2 structural features. [Conclusions]: These results indicate that transformer-2 is required for sex determination in Anastrepha through its participation in the female-specific splicing of transformer and doublesex pre-mRNAs. It is therefore needed for the auto-regulation of the gene transformer. Thus, the transformer/transfomer-2 > doublesex elements at the bottom of the cascade, and their relationships, probably represent the ancestral state (which still exists in the Tephritidae, Calliphoridae and Muscidae lineages) of the extant cascade found in the Drosophilidae lineage (in which tra is just another component of the sex determination gene cascade regulated by Sex-lethal). In the phylogenetic lineage that gave rise to the drosophilids, evolution co-opted for Sex-lethal, modified it, and converted it into the key gene controlling sex determination.
Description14 páginas, 6 figuras.
Additional information files can be downloaded from the BMC site: http://www.biomedcentral.com/1471-2148/10/140/additional/ 1. Number of nucleotides that compose the exons and introns of gene tra-2 of A. obliqua, C. capitata and D. melanogaster. Exons (boxes) and introns (lines) are not drawn to scale. Format: PPT, Size: 97KB for Microsoft PowerPoint Viewer. (http://www.biomedcentral.com/content/supplementary/1471-2148-10-140-s1.ppt) 2. Percentage similarity among the Anastrepha Tra2 proteins. Comparison of the Tra2 proteins of Anastrepha species. Format: DOC, Size: 55KB for Microsoft Word Viewer. (http://www.biomedcentral.com/content/supplementary/1471-2148-10-140-s2.doc) 3. Percentage similarity among the insect Tra2 proteins. Comparison of the Tra2 proteins of the insects so far characterised. A. obliqua was used as the reference species for the Anastrepha species. Format: DOC, Size: 55KB, for Microsoft Word Viewer. (http://www.biomedcentral.com/content/supplementary/1471-2148-10-140-s3.doc)
Publisher version (URL)http://dx.doi.org/10.1186/1471-2148-10-140
http://www.biomedcentral.com/1471-2148/10/140
URIhttp://hdl.handle.net/10261/33677
DOI10.1186/1471-2148-10-140
ISSN1471-2148
Appears in Collections:(CIB) Artículos
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