A new Drosophila melanogaster research resource: CRISPR-induced mutations for clonal analysis of fourth chromosome genes.

As part of an ongoing effort to generate comprehensive resources for the experimental analysis of fourth chromosome genes in Drosophila melanogaster, the Fourth Chromosome Resource Project has used CRISPR mutagenesis with single guide RNAs to isolate mutations in 62 of the 80 fourth chromosome, protein-coding genes. These mutations were induced on a fourth chromosome bearing a basal FRT insertion to facilitate experimental approaches involving FLP recombinase-induced mitotic recombination. To permit straightforward comparisons among mutant stocks, most of the mutations were generated on isogenic fourth chromosomes, which were then crossed into a common genetic background. Of the 119 mutations, 84 are frameshift mutations likely to be null alleles, 29 are small, in-frame deletions, and 6 have yet to be characterized molecularly. The mutations were tested for recessive lethal, female-sterile, and visible phenotypes. Stable stocks for most of the mutations have been submitted to repositories in the United States and Japan for public distribution.