GENE EXPRESSION DURING SEA LAMPREY EMBRYOGENESIS

These elimination events effectively silence all genes on these chromosomes in all somatic cells., and Pprevious studies in lamprey and other eliminating species have provided strong evidence that other epigenetic silencing marks (DNA and histone posttranslational modifications) are enriched in the germline-restricted chromosomes and contribute to micronucleus packaging during elimination.

These silencing marks include the histone marks H3K9me3 and H4K20me3, which are respectively deposited by KMT1A/SUV39 and KMT5/SUV420 methyltransferases in . To test whether lamprey homologs of methyltransferases contribute to deposition of these marks on elimination micronuclei and whether these marks contribute to the highly coordinated process of DNA elimination in sea lamprey, we leveraged CRISPR/Cas9 gene editing and lightsheet imaging to investigate their potential roles during early development and during the progression of DNA elimination.