RESUMO
CRISPR-Cas9 homing gene drives are designed to induce a targeted double-stranded DNA break at a wild type allele ('recipient'), which, when repaired by the host cell, is converted to the drive allele from the homologous ('donor') chromosome. Germline localisation of this process leads to super-Mendelian inheritance of the drive and the rapid spread of linked traits, offering a novel strategy for population control through the deliberate release of drive individuals. During the homology-based DNA repair, additional segments of the recipient chromosome may convert to match the donor, potentially impacting carrier fitness and strategy success. Using Anopheles gambiae strains with variations around the drive target site, here we assess the extent and nature of chromosomal conversion. We show both homing and meiotic drive contribute as mechanisms of inheritance bias. Additionally, over 80% of homing events resolve within 50 bp of the chromosomal break, enabling rapid gene drive transfer into locally-adapted genetic backgrounds.
Assuntos
Anopheles , Sistemas CRISPR-Cas , Tecnologia de Impulso Genético , Anopheles/genética , Animais , Tecnologia de Impulso Genético/métodos , Feminino , Alelos , Conversão Gênica , Meiose/genética , Masculino , Quebras de DNA de Cadeia Dupla , Cromossomos de Insetos/genéticaRESUMO
The human malaria vector Anopheles gambiae is becoming increasingly resistant to insecticides, spurring the development of genetic control strategies. CRISPR-Cas9 gene drives can modify a population by creating double-stranded breaks at highly specific targets, triggering copying of the gene drive into the cut site ("homing"), ensuring its inheritance. The DNA repair mechanism responsible requires homology between the donor and recipient chromosomes, presenting challenges for the invasion of laboratory-developed gene drives into wild populations of target species An. gambiae species complex, which show high levels of genome variation. Two gene drives (vas2-5958 and zpg-7280) were introduced into three An. gambiae strains collected across Africa with 5.3-6.6% variation around the target sites, and the effect of this variation on homing was measured. Gene drive homing across different karyotypes of the 2La chromosomal inversion was also assessed. No decrease in gene drive homing was seen despite target site heterology, demonstrating the applicability of gene drives to wild populations.
RESUMO
An efficient Lewis acid induced nitrogen-driven rearrangement iminium-trapping cascade from an epoxytropinone 3 gives a 7-allylated 6-azabicyclo[3.2.1]octan-3-one 2, which is converted into the alkaloid (+/-)-peduncularine (1).