Biology subjects

Saccone, G.

Publications and source records attributed to Saccone, G..

7 recordsLinked to original sources

bioRxiv2024

Simultaneous silencing of gut nucleases and a vital target gene by adult dsRNA feeding enhances RNAi efficiency and mortality in Ceratitis capitata adults.

Ceratitis capitata, known as Mediterranean fruit fly (Medfly), is a major dipteran pest significantly impacting fruit and vegetable farming. Currently, its control heavily relies mainly on chemical insecticides, which pose health risks and have effects on pollinators. A friendly and species-specific alternative strategy involves providing double-stranded RNA (dsRNA) through feeding to disrupt essential functions in pest insects, which is poorly explored in dipteran species. Previous reports in Orthoptera and Coleoptera species suggested that dsRNA degradation by two specific nucleases in the intestinal lumen is among the major obstacle to feeding-mediated RNAi in insects. In our study, we experimented with three-day adult feeding using a combination of dsRNA molecules that target the expression of the ATPase vital gene and two intestinal dsRNA nucleases. These dsRNA molecules were recently tested separately in two Tephritidae species, showing limited effectiveness [1,2]. In contrast, we observed 79% mortality over seven days, which was associated with a decrease in mRNA levels of the three targeted genes. As expected, we also observed a reduction in dsRNA degradation following RNAi against nucleases. This research illustrates the potential of utilizing molecules as pesticides to achieve mortality rates in Medfly adults by targeting crucial genes and intestinal nucleases. Furthermore, it underscores the importance of exploring RNAi-based approaches for pest management Simple SummaryThe control of insect pest species, mainly belonging to Orthoptera, Hemiptera, and Coleoptera species, can be based on novel emerging species-specific pesticides. These consist of dsRNA molecules delivered by feeding to insect larvae or adults, which suppress vital gene functions by RNA-RNA sequence complementarity and RNA interference. However, fewer studies of dsRNA feeding have been performed in dipteran pest insects. Two studies in Orthoptera and Coleoptera species have shown that suppressing intestinal enzymes degrading external dsRNA can improve insect mortality rates. Ceratitis capitata (Tephritidae), the Mediterranean fruit fly (Medfly), is a major dipteran pest significantly impacting fruit and vegetable farming. Currently, its control heavily relies mainly on chemical insecticides, which pose health risks and have effects on beneficial pollinators. Previous attempts to induce mortality by adult dsRNA-feeding in this and other Tephritidae species, such as Bactrocera tryoni and B. dorsalis, showed some effectiveness, but were often limited. We improved this method by simultaneously silencing two intestinal nucleases and a vital gene. We have found a mix of three dsRNAs able to induce much higher mortality (79%) within one week, following only three days of adult feeding.

genetics↗

bioRxiv2021

Aedes albopictus bionomics in Procida Island, a promising Mediterranean site for the assessment of innovative and community-based integrated pest management methods.

The colonization of Mediterranean Europe and of other temperate regions by Aedes albopictus created in the last decades an unprecedented nuisance problem in highly infested areas, as well as a new public health threat due to the species competence to transmit exotic arboviruses, such as dengue, chikungunya and zika. The Sterile Insect Technique (SIT) and the Incompatible Insect Technique (IIT) are insecticide-free mosquito-control methods relying on mass release of irradiated/manipulated males which are believed to have a potential in complementing existing and only partially effective control tools. Testing and implementing these approaches are challenging and selection of study sites is an instrumental and crucial step. We carried out a 4-year study in Procida Island (Gulf of Naples, Italy) in strict collaboration with local administrators and citizens to estimate: i) the temporal dynamics, spatial distribution, and population size of Ae. albopictus; and ii) the dispersal and survival of irradiated males. Overall, results provide insights on the bionomics of the mosquito in Southern Europe and draw attention to Procida Island as an ideal site to test innovative control programs against Ae. albopictus which may be used in other Mediterranean and temperate areas."

ecology↗

bioRxiv2019

Maleness-on-the-Y (MoY) orchestrates male sex determination in major agricultural fruit fly pests

In insects, rapidly evolving primary sex-determining signals are transduced by a conserved regulatory module producing sex-specific proteins that direct sex determination and sexual differentiation1-4. In the agricultural pest Ceratitis capitata (medfly), a Y-linked maleness factor (M) is thought to repress the autoregulatory splicing of transformer (Cctra), which is required in XX individuals to establish and maintain female sex determination5,6. Despite previous attempts of isolating Y-linked genes using the medfly whole genome, the M factor has remained elusive7. Here, we report the identification of a Y-linked gene, Maleness-on the-Y (MoY), and show that it encodes a small novel protein which is both necessary and sufficient for medfly male sex determination. Transient silencing of MoY in XY individuals leads to the development of fertile females while transient expression of MoY in XX individuals results in fertile males. Notably, a cross between these sex reverted individuals gives rise to both fertile males and females indicating that a functional MoY can be maternally transmitted. In contrast to the diversity of M factors found in dipteran species8-11, we discovered MoY orthologues in seven other Tephritid species spanning [~]111 millions of years of evolution (Mya). We confirmed their male determining function in the olive fly (Bactrocera oleae) and the oriental fruit fly (Bactrocera dorsalis). This unexpected conservation of the primary MoY signal in a large number of important agricultural pests12 will facilitate the development of transferable genetic control strategies in these species, for example sterile male releases or sex-ratio-distorting gene drives.

genetics↗

bioRxiv2019

Genomics and transcriptomics to unravel sex determination pathway and its evolution in sand flies

BackgroundPhlebotomine sand flies (Diptera, Nematocera) are important vectors of several pathogens, including Leishmania parasites, causing serious diseases of humans and dogs. Despite their importance as disease vectors, most aspects of sand fly biology remain unknown including the molecular bases of their reproduction and sex determination, aspects also relevant for the development of novel vector control strategies.\n\nResultsUsing a comparative genomics/transcriptomics approach, we identified the sex determining genes in phlebotomine sand flies and proposed the first model for the sex determination cascade of these insects. For all the genes identified, we produced manually curated gene models, developmental gene expression profile and performed evolutionary molecular analysis. We identified and characterized, for the first time in a Nematocera species, the transformer (tra) homolog which exhibits both conserved and novel features. The analysis of the tra locus in sand flies and its expression pattern suggest that this gene is able to autoregulate its own splicing, as observed in the fruit fly Ceratitis capitata and several other insect species.\n\nConclusionsOur results permit to fill the gap about sex determination in sand flies, contribute to a better understanding of this developmental pathway in Nematocera and open the way for the identification of sex determining orthologs in other species of this important Diptera sub-order. Furthermore, the sex determination genes identified in our work also provide the opportunity of future biotech applications to control natural population of sand flies, reducing their impact on public health.

genomics↗

bioRxiv2017

Molluscs community associated with the brown algae of the genus Cystoseira in the Gulf of Naples (South Tyrrhenian Sea)

The brown macroalgae of the genus Cystoseira are important habitat forming species along the rocky coasts all over the Mediterranean Sea. However, their decline at basin and local scale has been documented in many studies. We have characterized malacofauna associated with Cystoseira amentacea, C. compressa and C. crinita along the coasts of Ischia Island (Gulf of Naples). Samples were collected by snorkeling in the infralittoral belt. The surface within 20 x 20 cm frames was scraped off and collected in three replicates each sites. The diversity and structure of community were described by number of species, the exponential Shannon and the reciprocal Simpsons indexes of diversity. The patterns of diversity at spatial scale were assessed by alpha, beta and gamma diversity. A total of 53 species of molluscs were identified in those associations. Gastropoda were the most species-rich class followed by Bivalvia and Polyplacophora. Bivalves were dominant in terms of number of individuals because of the mussel Mytilus galloprovincialis. The species M. galloprovincialis was the most frequent and top dominant one inhabiting Cystoseira associations along the coasts of Ischia Island (96.6 % of the total abundance). Most of the identified molluscs species belonged to two feeding guilds: micrograzers and filter feeders (29 and 13 species respectively). Only juveniles were found providing the importance of Cystoseira associations as nursery for molluscs recruitment. Differences in composition and structure of molluscs assemblages were found within the three algal associations and seem to correspond both to different morphology and habitat in which these algal species live.

ecology↗

bioRxiv2017

Highly efficient DNA-free gene disruption in the agricultural pest Ceratitis capitata by CRISPR-Cas9 RNPs

The Mediterranean fruitfly Ceratitis capitata (medfly) is an invasive agricultural pest of high economical impact and has become an emerging model for developing new genetic control strategies as 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 sgRNAs into early embryos. When targeting the eye pigmentation gene white eye (we), we observed a high rate of somatic mosaicism in surviving G0 adults. Germline transmission of mutated we alleles by G0 animals was on average above 70%, with individual cases achieving a transmission rate of 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 and in hatched larvae. Mutant phenotypes correlate with repair by non-homologous end joining (NHEJ) lesions in the two targeted genes. This simple and highly effective Cas9 RNP-based gene editing to introduce mutations in Ceratitis capitata will significantly advance the design and development of new effective strategies for pest control management.

genetics↗

bioRxiv2017

CRISPR-Cas9 targeted disruption of the yellow ortholog in the housefly identifies the brown body locus

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 the Musca model.

genetics↗