Tonight, I watched the London Calling 2024 session by Julie Dragon from the University of Vermont. The title was “Shining Light on a Dark Mystery: melanoma in Bullhead Benthic Fish in Lake Memphremagog.” Dragon stated the problem: melanoma is found consistently in 30% of one species of fish in one lake! The brown bullhead is a type of catfish that lives on the bottom of Lake Memphremagog and is shared by Vermont and Quebec. Brown bullheads have lesions from punctate dots to multiple raised lesions. Melanoma in these fish may be due to UV light exposure or a local landfill leachate. Some speculated that the cause could also be the genomic background of the brown bullhead fish. Dragon and the team collected fish samples for population genomics and a reference genome. Colleagues may perform microbiome analyses. The team assembled the genome from PromethION flow cell runs using Native Barcoding Sequencing Kit RB SQK-NBD114.24 and Singular G4 short read. The team assembled with Pegasus and annotated with Funannotate. Methylation status was analyzed with DeepMod2. Genome and coverage varied. Population genomics of almost 200 fish indicated that the affected fish are different from the reference. Based on posterior membership probability, the Lake Memphremagog fish are similar with some indications of mixing. Gene expression of affected fish did reveal some tumor-related genes. Somatic variants identified are also known for tumorigenesis. The team has begun to learn that there is increased methylation of key GPCR proteins. This session was not what I expected, and it gave me several ideas for the waxworm project!
