Parasitic Worm Genomes Lack Genes Expected in All Animals

Members of the phylum Nematomorpha — a group of parasitic worms that are known to affect the behavior of their insect hosts — lack about 30 percent of the genes they are expected to have, a Harvard University-led research team reports. The team generated chromosome-level assemblies for the freshwater Acutogordius australiensis and the marine Nectonema munidae using a combination of Nanopore long reads and Illumina read polishing. But as they report in Current Biology, the researchers found that the worms were missing a number of genes expected to be found among all animals. After confirming the missing genes were not a sequencing artifact, the researchers note that the missing genes included ones linked to cilia and cell projections. "Based on previous observations, it didn't seem like hairworms had any cilia, but we didn't really know for sure," first author Tauana Cunha, a postdoc at the Field Museum in Chicago, says in a statement. "Now with the genomes, we saw that they actually lack the genes that produce cilia in other animals — they don't have the machinery to make cilia in the first place." She adds that it is as yet unclear whether this lack of cilia genes is associated with the worms' parasitic lifestyle.