Limits...
Australian endemic pest tephritids: genetic, molecular and microbial tools for improved Sterile Insect Technique.

Raphael KA, Shearman DC, Gilchrist AS, Sved JA, Morrow JL, Sherwin WB, Riegler M, Frommer M - BMC Genet. (2014)

Bottom Line: Transcriptomes from various species, tissues and developmental stages, to aid in identification of manipulation targets for improving SIT, have been assembled and are in the pipeline.Broad analyses of the microbiome have revealed a metagenome that is highly variable within and across species and defined by the environment.More specific analyses detected Wolbachia at low prevalence in the tropics but absent in temperate regions, suggesting a possible role for this endosymbiont in future control strategies.

View Article: PubMed Central - HTML - PubMed

ABSTRACT
Among Australian endemic tephritid fruit flies, the sibling species Bactrocera tryoni and Bactrocera neohumeralis have been serious horticultural pests since the introduction of horticulture in the nineteenth century. More recently, Bactrocera jarvisi has also been declared a pest in northern Australia. After several decades of genetic research there is now a range of classical and molecular genetic tools that can be used to develop improved Sterile Insect Technique (SIT) strains for control of these pests. Four-way crossing strategies have the potential to overcome the problem of inbreeding in mass-reared strains of B. tryoni. The ability to produce hybrids between B. tryoni and the other two species in the laboratory has proved useful for the development of genetically marked strains. The identification of Y-chromosome markers in B. jarvisi means that male and female embryos can be distinguished in any strain that carries a B. jarvisi Y chromosome. This has enabled the study of homologues of the sex-determination genes during development of B jarvisi and B. tryoni, which is necessary for the generation of genetic-sexing strains. Germ-line transformation has been established and a draft genome sequence for B. tryoni released. Transcriptomes from various species, tissues and developmental stages, to aid in identification of manipulation targets for improving SIT, have been assembled and are in the pipeline. Broad analyses of the microbiome have revealed a metagenome that is highly variable within and across species and defined by the environment. More specific analyses detected Wolbachia at low prevalence in the tropics but absent in temperate regions, suggesting a possible role for this endosymbiont in future control strategies.

Show MeSH

Related in: MedlinePlus

RNAi in B. tryoni with transformer and transformer-2. (a) Diagramatic representation of dsRNA used to inject B. tryoni early embryos. Four different dsRNA fragments were designed to cover either overlapping thirds or the entire transcript of both female-specific tra and non-sex specific tra-2. (b) Preliminary results for injections of dsRNA fragments of both tra and tra-2 into either 3 hour or 7 hour embryos of B. tryoni. (c) Results of crosses between transformed males and wildtype females. In two cases (1) all progeny that resulted were female. In other cases (2) normal 1:1 male:female ratios were observed.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4255846&req=5

Figure 5: RNAi in B. tryoni with transformer and transformer-2. (a) Diagramatic representation of dsRNA used to inject B. tryoni early embryos. Four different dsRNA fragments were designed to cover either overlapping thirds or the entire transcript of both female-specific tra and non-sex specific tra-2. (b) Preliminary results for injections of dsRNA fragments of both tra and tra-2 into either 3 hour or 7 hour embryos of B. tryoni. (c) Results of crosses between transformed males and wildtype females. In two cases (1) all progeny that resulted were female. In other cases (2) normal 1:1 male:female ratios were observed.

Mentions: Elimination of either tra or tra-2 by RNAi early in development disrupts the mechanism favouring female-specific splicing of tra and dsx in C. capitata, B. oleae and Anastrepha spp. [69,70,72-74] and leads to the expression of dsxM and the consequent development of male somatic tissue [75]. Preliminary assessment of tra and tra-2 in B. tryoni (Bttra and Bttra-2) suggests the same functionality. Injection of full-length Bttra-2 and partial Bttra dsRNA fragments into B. tryoni embryos of 3h and 7h AEL was performed (Figure 5), with seven intersexes recovered from Bttra-2 injections into 7h embryos suggesting incomplete phenotypic conversion. Complete conversion resulted from Bttra injections of 3h embryos, whereby two phenotypic males developed that sired all female offspring when mated to a normal female (Figure 5). Thus, either gene can independently induce sex reversal and both genes may also be useful targets for transgenic RNAi in this species. Concommitant injections of buffer showed only marginally higher pupation rates than injections with dsRNA fragments suggesting physical handling was the greatest influence on the resultant numbers of emerged adults.


Australian endemic pest tephritids: genetic, molecular and microbial tools for improved Sterile Insect Technique.

Raphael KA, Shearman DC, Gilchrist AS, Sved JA, Morrow JL, Sherwin WB, Riegler M, Frommer M - BMC Genet. (2014)

RNAi in B. tryoni with transformer and transformer-2. (a) Diagramatic representation of dsRNA used to inject B. tryoni early embryos. Four different dsRNA fragments were designed to cover either overlapping thirds or the entire transcript of both female-specific tra and non-sex specific tra-2. (b) Preliminary results for injections of dsRNA fragments of both tra and tra-2 into either 3 hour or 7 hour embryos of B. tryoni. (c) Results of crosses between transformed males and wildtype females. In two cases (1) all progeny that resulted were female. In other cases (2) normal 1:1 male:female ratios were observed.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4255846&req=5

Figure 5: RNAi in B. tryoni with transformer and transformer-2. (a) Diagramatic representation of dsRNA used to inject B. tryoni early embryos. Four different dsRNA fragments were designed to cover either overlapping thirds or the entire transcript of both female-specific tra and non-sex specific tra-2. (b) Preliminary results for injections of dsRNA fragments of both tra and tra-2 into either 3 hour or 7 hour embryos of B. tryoni. (c) Results of crosses between transformed males and wildtype females. In two cases (1) all progeny that resulted were female. In other cases (2) normal 1:1 male:female ratios were observed.
Mentions: Elimination of either tra or tra-2 by RNAi early in development disrupts the mechanism favouring female-specific splicing of tra and dsx in C. capitata, B. oleae and Anastrepha spp. [69,70,72-74] and leads to the expression of dsxM and the consequent development of male somatic tissue [75]. Preliminary assessment of tra and tra-2 in B. tryoni (Bttra and Bttra-2) suggests the same functionality. Injection of full-length Bttra-2 and partial Bttra dsRNA fragments into B. tryoni embryos of 3h and 7h AEL was performed (Figure 5), with seven intersexes recovered from Bttra-2 injections into 7h embryos suggesting incomplete phenotypic conversion. Complete conversion resulted from Bttra injections of 3h embryos, whereby two phenotypic males developed that sired all female offspring when mated to a normal female (Figure 5). Thus, either gene can independently induce sex reversal and both genes may also be useful targets for transgenic RNAi in this species. Concommitant injections of buffer showed only marginally higher pupation rates than injections with dsRNA fragments suggesting physical handling was the greatest influence on the resultant numbers of emerged adults.

Bottom Line: Transcriptomes from various species, tissues and developmental stages, to aid in identification of manipulation targets for improving SIT, have been assembled and are in the pipeline.Broad analyses of the microbiome have revealed a metagenome that is highly variable within and across species and defined by the environment.More specific analyses detected Wolbachia at low prevalence in the tropics but absent in temperate regions, suggesting a possible role for this endosymbiont in future control strategies.

View Article: PubMed Central - HTML - PubMed

ABSTRACT
Among Australian endemic tephritid fruit flies, the sibling species Bactrocera tryoni and Bactrocera neohumeralis have been serious horticultural pests since the introduction of horticulture in the nineteenth century. More recently, Bactrocera jarvisi has also been declared a pest in northern Australia. After several decades of genetic research there is now a range of classical and molecular genetic tools that can be used to develop improved Sterile Insect Technique (SIT) strains for control of these pests. Four-way crossing strategies have the potential to overcome the problem of inbreeding in mass-reared strains of B. tryoni. The ability to produce hybrids between B. tryoni and the other two species in the laboratory has proved useful for the development of genetically marked strains. The identification of Y-chromosome markers in B. jarvisi means that male and female embryos can be distinguished in any strain that carries a B. jarvisi Y chromosome. This has enabled the study of homologues of the sex-determination genes during development of B jarvisi and B. tryoni, which is necessary for the generation of genetic-sexing strains. Germ-line transformation has been established and a draft genome sequence for B. tryoni released. Transcriptomes from various species, tissues and developmental stages, to aid in identification of manipulation targets for improving SIT, have been assembled and are in the pipeline. Broad analyses of the microbiome have revealed a metagenome that is highly variable within and across species and defined by the environment. More specific analyses detected Wolbachia at low prevalence in the tropics but absent in temperate regions, suggesting a possible role for this endosymbiont in future control strategies.

Show MeSH
Related in: MedlinePlus