Biology subjects

Gantz, V.

Publications and source records attributed to Gantz, V..

3 recordsLinked to original sources

bioRxiv2025

Sequence mismatch between gene-drive and target-site flanking regions significantly impairs homing efficiency in Culex quinquefasciatus

CRISPR/Cas9-based homing gene-drives (homing-drives) hold enormous potential as control tools for mosquito disease-vectors. These genomically-encoded technologies spread themselves through target populations by creating double-stranded DNA breaks on homologous chromosomes, into which the homing-drives are copied ( homed). Homing is dependent on sequence homology between the genomic regions flanking the transgene insertion and the break site. Homing efficiency (i.e. copying rate) substantially impacts the power of these systems: less efficient homing-drives spread slower, have fewer applications and are more resistance-prone. Understanding what influences homing-drive efficiency is therefore vital to the successful use of these technologies. Here we report a novel mechanism by which a homing-drives efficiency can be significantly impaired by natural sequence variation within a population into which it is spreading. Using a kmo-targeting split homing-drive in the West Nile virus mosquito Culex quinquefasciatus, we found that target-site heterology (sequence mismatch between the genomic regions flanking the target cut-site and the homing-drive transgene) of less than 10% reduced homing efficiency by up to 54%. While substantial research effort has been dedicated to increasing homing-drive efficiency through optimisation of within-construct components, our results highlight that the real-world efficacy of these systems may in part depend on variation beyond these controllable factors.

synthetic biology↗

bioRxiv2025

Genomic Resources for the Scuttle Fly Megaselia abdita: A Model Organism for Comparative Developmental Studies in Flies

The order Diptera (true flies) holds promise as a model taxon in evolutionary developmental biology due to the inclusion of the model organism, Drosophila melanogaster, and the ability to cost-effectively rear many species in laboratories. One of them, the scuttle fly Megaselia abdita (Phoridae) has been used in evolutionary developmental biology for 30 years and is an excellent phylogenetic intermediate between fruit flies and mosquitoes but remains underdeveloped in genomic resources. Here, we present a de novo chromosome-level assembly and annotation of M. abdita and transcriptomes of 9 embryonic and 4 postembryonic stages. We also compare 9 stage-matched embryonic transcriptomes between M. abdita and D. melanogaster. Our analysis of these resources reveals extensive chromosomal synteny with D. melanogaster, 28 orphan genes with embryo-specific expression including a novel F-box LRR gene in M. abdita, and conserved and diverged features of gene expression dynamics between M. abdita and D. melanogaster. Collectively, our results provide a new reference for studying the diversification of developmental processes in flies.

developmental biology↗

bioRxiv2022

ROBUST AND EFFICIENT ACTIVE GENETICS GENE CONVERSION IN THE RAT AND MOUSE

The utility of Active Genetic (AG) gene conversion systems in rats and mice holds great promise for facilitating the production of complex strains harboring multiple humanizing genes. The practical application of such systems requires the identification of a robust, reusable, and highly efficient system. By characterizing twenty-eight different promoter and target site pairs we aimed to define the parameters needed to establish an efficient conversion system in male and female rats and mice. Using three specific meiosis prophase I active promoters to drive Cas9 expression. We studied several variables, including the number of Cas9 target sites, the distance between target sites, the cis versus trans configuration in linked pairs, and the effect of Cas9 copy number. In the rat, three of twelve tested configurations provided efficient AG gene conversion in the 22% - 67% range, and four others catalyzed AG in the 0.7-1% range. The rat Ddx4 (Vasa) promoter provides higher AG efficiency than the Sycp1 promoter. In mice, ten of sixteen tested configurations, using the Sycp1 and pSycp1 promoters, provided efficiency in the 0.3% - 3.2% range. In rats, Cas9 expression levels are remarkably well correlated with AG gene conversion efficiency. The rat cis rCyp3A1/rCyp3A2 locus was the most successful configuration, with gene conversion efficiencies of 0.7%-67%. This target site has a special property; the two Cas9 target sites are nearly perfectly homologous in the 100 bases around the gRNA target site. Our findings identify key parameters that improve AG efficiency, including the use of two Cas9 target sites, and efficient promoters that drive high levels of Cas9 expression that are correctly timed during gamete development. These findings also uncover the unexpected benefit of high homology at paired gRNA target sites to promote efficiency. We provide new data to guide future efforts to develop yet further improved AG systems.

genetics↗