The medfly Ceratitis capitata contains a gene (Cctra) with structural and functional homology to ... more The medfly Ceratitis capitata contains a gene (Cctra) with structural and functional homology to the Drosophila melanogaster sex-determining gene transformer (tra). Similar to tra in Drosophila, Cctra is regulated by alternative splicing such that only females can encode a full-length protein. In contrast to Drosophila, however, where tra is a subordinate target of Sex-lethal (Sxl), Cctra seems to initiate an autoregulatory mechanism in XX embryos that provides continuous tra female-specific function and act as a cellular memory maintaining the female pathway. Indeed, a transient interference with Cctra expression in XX embryos by RNAi treatment can cause complete sexual transformation of both germline and soma in adult flies, resulting in a fertile male XX phenotype. The male pathway seems to result when Cctra autoregulation is prevented and instead splice variants with truncated open reading frames are produced. We propose that this repression is achieved by the Y-linked male-dete...
The Mediterranean fruitfly Ceratitis capitata (medfly) is an invasive agricultural pest of high e... more The Mediterranean fruitfly Ceratitis capitata (medfly) is an invasive agricultural pest of high economic impact and has become an emerging model for developing new genetic control strategies as an alternative to insecticides. Here, we report the successful adaptation of CRISPR-Cas9-based gene disruption in the medfly by injecting in vitro pre-assembled, solubilized Cas9 ribonucleoprotein complexes (RNPs) loaded with gene-specific single guide RNAs (sgRNA) into early embryos. When targeting the eye pigmentation gene white eye (we), a high rate of somatic mosaicism in surviving G0 adults was observed. Germline transmission rate of mutated we alleles by G0 animals was on average above 52%, with individual cases achieving nearly 100%. We further recovered large deletions in the we gene when two sites were simultaneously targeted by two sgRNAs. CRISPR-Cas9 targeting of the Ceratitis ortholog of the Drosophila segmentation paired gene (Ccprd) caused segmental malformations in late embryos...
The classic brown body (bwb) mutation in the housefly Musca domestica impairs normal melanization... more The classic brown body (bwb) mutation in the housefly Musca domestica impairs normal melanization of the adult cuticle. In Drosophila melanogaster, a reminiscent pigmentation defect results from mutations in the yellow gene encoding dopachrome conversion enzyme (DCE). Here, we demonstrate that the bwb locus structurally and functionally represents the yellow ortholog of Musca domestica, MdY. In bwb Musca strains, we identified two mutant MdY alleles that contain lesions predicted to result in premature truncation of the MdY open reading frame. We targeted wildtype MdY by CRISPR-Cas9 RNPs and generated new mutant alleles that fail to complement existing MdY alleles, genetically confirming that MdY is the bwb locus. We further found evidence for Cas9-mediated interchromosomal recombination between wildtype and mutant bwb alleles. Our work resolves the molecular identity of the classic bwb mutation in Musca domestica and establishes the feasibility of Cas9-mediated genome editing in th...
The Mediterranean fruit fly (medfly), Ceratitis capitata, is a major destructive insect pest due ... more The Mediterranean fruit fly (medfly), Ceratitis capitata, is a major destructive insect pest due to its broad host range, which includes hundreds of fruits and vegetables. It exhibits a unique ability to invade and adapt to ecological niches throughout tropical and subtropical regions of the world, though medfly infestations have been prevented and controlled by the sterile insect technique (SIT) as part of integrated pest management programs (IPMs). The genetic analysis and manipulation of medfly has been subject to intensive study in an effort to improve SIT efficacy and other aspects of IPM control. The 479 Mb medfly genome is sequenced from adult flies from lines inbred for 20 generations. A high-quality assembly is achieved having a contig N50 of 45.7 kb and scaffold N50 of 4.06 Mb. In-depth curation of more than 1800 messenger RNAs shows specific gene expansions that can be related to invasiveness and host adaptation, including gene families for chemoreception, toxin and insec...
The medfly Ceratitis capitata contains a gene (Cctra) with structural and functional homology to ... more The medfly Ceratitis capitata contains a gene (Cctra) with structural and functional homology to the Drosophila melanogaster sex-determining gene transformer (tra). Similar to tra in Drosophila, Cctra is regulated by alternative splicing such that only females can encode a full-length protein. In contrast to Drosophila, however, where tra is a subordinate target of Sex-lethal (Sxl), Cctra seems to initiate an autoregulatory mechanism in XX embryos that provides continuous tra female-specific function and act as a cellular memory maintaining the female pathway. Indeed, a transient interference with Cctra expression in XX embryos by RNAi treatment can cause complete sexual transformation of both germline and soma in adult flies, resulting in a fertile male XX phenotype. The male pathway seems to result when Cctra autoregulation is prevented and instead splice variants with truncated open reading frames are produced. We propose that this repression is achieved by the Y-linked male-dete...
The Mediterranean fruitfly Ceratitis capitata (medfly) is an invasive agricultural pest of high e... more The Mediterranean fruitfly Ceratitis capitata (medfly) is an invasive agricultural pest of high economic impact and has become an emerging model for developing new genetic control strategies as an alternative to insecticides. Here, we report the successful adaptation of CRISPR-Cas9-based gene disruption in the medfly by injecting in vitro pre-assembled, solubilized Cas9 ribonucleoprotein complexes (RNPs) loaded with gene-specific single guide RNAs (sgRNA) into early embryos. When targeting the eye pigmentation gene white eye (we), a high rate of somatic mosaicism in surviving G0 adults was observed. Germline transmission rate of mutated we alleles by G0 animals was on average above 52%, with individual cases achieving nearly 100%. We further recovered large deletions in the we gene when two sites were simultaneously targeted by two sgRNAs. CRISPR-Cas9 targeting of the Ceratitis ortholog of the Drosophila segmentation paired gene (Ccprd) caused segmental malformations in late embryos...
The classic brown body (bwb) mutation in the housefly Musca domestica impairs normal melanization... more The classic brown body (bwb) mutation in the housefly Musca domestica impairs normal melanization of the adult cuticle. In Drosophila melanogaster, a reminiscent pigmentation defect results from mutations in the yellow gene encoding dopachrome conversion enzyme (DCE). Here, we demonstrate that the bwb locus structurally and functionally represents the yellow ortholog of Musca domestica, MdY. In bwb Musca strains, we identified two mutant MdY alleles that contain lesions predicted to result in premature truncation of the MdY open reading frame. We targeted wildtype MdY by CRISPR-Cas9 RNPs and generated new mutant alleles that fail to complement existing MdY alleles, genetically confirming that MdY is the bwb locus. We further found evidence for Cas9-mediated interchromosomal recombination between wildtype and mutant bwb alleles. Our work resolves the molecular identity of the classic bwb mutation in Musca domestica and establishes the feasibility of Cas9-mediated genome editing in th...
The Mediterranean fruit fly (medfly), Ceratitis capitata, is a major destructive insect pest due ... more The Mediterranean fruit fly (medfly), Ceratitis capitata, is a major destructive insect pest due to its broad host range, which includes hundreds of fruits and vegetables. It exhibits a unique ability to invade and adapt to ecological niches throughout tropical and subtropical regions of the world, though medfly infestations have been prevented and controlled by the sterile insect technique (SIT) as part of integrated pest management programs (IPMs). The genetic analysis and manipulation of medfly has been subject to intensive study in an effort to improve SIT efficacy and other aspects of IPM control. The 479 Mb medfly genome is sequenced from adult flies from lines inbred for 20 generations. A high-quality assembly is achieved having a contig N50 of 45.7 kb and scaffold N50 of 4.06 Mb. In-depth curation of more than 1800 messenger RNAs shows specific gene expansions that can be related to invasiveness and host adaptation, including gene families for chemoreception, toxin and insec...
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Papers by giuseppe saccone