There’s a lot to love about the new preprint announcing the first-ever truly high-quality reference genome assembly for the Aedes aegypti mosquito. The large consortium of scientists — the paper features a total of 72 co-authors — came together on its own, with researchers signing on in droves after a tweeted plea from mosquito researcher Leslie Vosshall. The project took two years and yielded a remarkably complete assembly with a contig N50 of nearly 12 Mb. Here at Sage Science, we’re also delighted to see that two of our automated DNA size selection instruments, the SageELF and BluePippin, were used to prepare libraries for sequencing.
The preprint, currently titled “Improved Aedes aegypti mosquito reference genome assembly enables biological discovery and vector control,” comes from lead authors Benjamin Matthews, Olga Dudchenko, and Sarah Kingan. Scientists on the project hailed from Rockefeller University, Baylor College of Medicine, NHGRI, and dozens of other institutions.
Launched during the height of the Zika virus outbreak, the consortium aimed to generate a more complete and contiguous assembly for Aedes aegypti than was previously available. Since the mosquito genome is repetitive and spans more than a gigabase, prior assemblies were marked by thousands of gaps, short contigs, and sequence that couldn’t be mapped to chromosomes. “We used long-read Pacific Biosciences sequencing and Hi-C scaffolding to produce a new reference genome (AaegL5) that is highly contiguous, representing a decrease of 93% in the number of contigs, and anchored end-to-end to the three Ae. aegypti chromosomes,” the scientists report. They also produced a complete assembly of the mitochondrial genome with zero gaps.
Deep dives into the final assembly prove that it is more accurate and complete than previous resources, with more robust gene predictions. “The high-quality genome assembly and annotation described here will enable major advances in mosquito biology and has already allowed us to carry out a number of experiments that were previously impossible,” the team writes. For instance, they identified new candidate loci that appear to be associated with competence as a vector of dengue virus. They also learned more about the sex-determining mechanism, which is important for efforts to shift mosquito populations toward harmless-to-human males.
All in all, the scientists conclude, this new assembly should allow the community to make major strides in understanding mosquito biology and controlling their impact on human health.