Biology subjects

Fasulo, B.

Publications and source records attributed to Fasulo, B..

4 recordsLinked to original sources

bioRxiv2026

Essential function of femaleless in female gametogenesis controls gene drive spread in Anopheles gambiae

Insecticide resistance in mosquito vectors and antimalarial drug resistance in parasites threaten progress towards malaria elimination, prompting the development of alternative control strategies such as CRISPR-Cas9 gene drives. The sex determination gene femaleless (fle, AGAP013051), which is required for female development in Anopheles gambiae, is a promising target for population-suppression approaches aimed at disrupting female-specific genes that affect fertility or viability. However, its functions beyond sex determination remain unknown. Here, we engineered homing gene drives targeting fle and employed germline promoters with distinct temporal expression profiles, early-acting , zero population growth (zpg, AGAP006241) and late-acting sporulation defective 11 (spo11, AGAP010898), to modulate Cas9 activity. The zpg-driven system achieved up to 98% transmission through males but caused complete sterility in hemizygous females due to early biallelic disruption of fle during germline development. Delaying cas9 expression with the spo11 promoter partially restored female fertility, although female transmission remained close to Mendelian levels (59%). These results reveal an essential role for fle in female gametogenesis in addition to its established function in sex determination. Population modelling predicts that releasing zpg-drive males at 16.9% of the wild-type male population could reduce female abundance by 95% within 36 generations. Collectively, our findings reveal a previously unrecognised reproductive function of fle that limits gene-drive spread and provide important insights for the design of vector-control strategies targeting genes with essential germline functions.

synthetic biology↗

bioRxiv2025

A male-drive female-sterile system for the self-limited control of the malaria mosquito Anopheles gambiae

The use of insecticides and antimalarial drugs has been crucial in reducing the mortality and morbidity associated with malaria. However, since 2015, several challenges, including the development of resistance to these insecticides and treatments and changes in mosquito behaviour, have hindered the progress in fighting the disease. As a result, there is a pressing need for new tools to control malaria, including the potential use of genetically modified mosquitoes (GMMs) in the field. Various genetic strategies for vector control are currently being explored, ranging from self-sustaining GMMs with unrestricted geographic and temporal spread to self-limiting alternatives. Here, we propose a self-limiting gene drive strategy called Male Drive Female Sterile (MDFS) targeting Anopheles gambiae, a major malaria vector. The MDFS genetic construct causes dominant sterility in females, while transgenic males remain fertile, allowing them to transmit the female sterility trait at super-Mendelian rates. Laboratory studies have shown that repeated releases of MDFS can lead to the elimination of caged mosquito populations. Based on these findings, modelling suggests that MDFS could be a highly effective and self-limiting strategy for suppressing wild malaria mosquito populations.

molecular biology↗

bioRxiv2020

Engineered sex distortion in the global agricultural pest Ceratitis capitata

Genetic sex ratio distorters have potential for the area-wide control of harmful insect populations. Endonucleases targeting the X-chromosome and whose activity is restricted to male gametogenesis have recently been pioneered as a means to engineer such traits. Here we enabled endogenous CRISPR/Cas9 and CRISPR/Cas12a activity during spermatogenesis of the Mediterranean fruit fly Ceratitis capitata, a worldwide agricultural pest of extensive economic significance. In the absence of a chromosome-level assembly, we analysed long and short-read genome sequencing data from males and females to identify two clusters of abundant and X-chromosome specific sequence repeats. When targeted by gRNAs in conjunction with Cas9 they yielded a significant and consistent distortion of the sex ratio in independent transgenic strains and a combination of distorters induced a strong bias towards males (~80%). Our results demonstrate the design of sex distorters in a non-model organism and suggest that strains with characteristics suitable for field application could be developed for a range of medically or agriculturally relevant insect species.

synthetic biology↗

bioRxiv2019

A fly model establishes distinct mechanisms for synthetic CRISPR/Cas9 sex distorters

Synthetic sex distorters have recently been developed in the malaria mosquito, relying on endonucleases that target the X-chromosome during spermatogenesis. Although inspired by naturally-occurring traits, it has remained unclear how they function and, given their potential for genetic control, how portable this strategy is across species. We established Drosophila models for two distinct mechanisms for CRISPR/Cas9 sex-ratio distortion - "X-shredding" and "X-meddling" - and dissected their target-site requirements and repair dynamics. X-shredding relies on sufficient meiotic activity of the endonuclease to overpower DNA repair and can operate on a single repeat cluster of non-essential sequences. X-meddling by contrast, i.e. targeting putative haplolethal X-linked genes, induced a bias towards males that is coupled to a loss in reproductive output, although a dominant-negative effect may drive the mechanism of female lethality. Our model system will guide the study and the application of sex distorters to medically or agriculturally important insect target species.

synthetic biology↗