KENDALL, Lindsay R.*; MCMULLIN, Erin; MARSH, Adam G.; University of Delaware; University of Delaware; University of Delaware: Genome methylation patterns during early development in the Antarctic sea urchin, Sterechinus neumayeri

Some polar-adapted marine invertebrates such as the Antarctic sea urchin Sterechinus neumayeri exhibit slow rates of development with extended cell-cycle periods (> 12 h). This extended developmental period makes time-series sampling possible at a finer scale than is attainable with temperate species. In S. neumayeri embryos, we have identified changes in genome methylation patterns during development using a method based on amplified fragment length polymorphisms (AFLP) that is sensitive to the presence of 5'-methylcytosine nucleotides. This assay, the Methylation Sensitive Amplified Polymorphisms (MSAP), identifies and amplifies fragments containing methylated recognition sites. Cohorts of embryos from individual female Antarctic sea urchins (Sterechinus neumayeri) were sampled over developmental time at a fine-scale resolution. Samples taken through the MSAP technique were visualized by polyacrylamide gel electrophoresis. Each sample lane was scored as a + (band present) or a - (band absent) by visual examination of the gel. A binary matrix was created from all sample data and methylation patterns compared across time and between cohorts of different females for each different primer pair combination. Methylation patterns that were repeated in more than one cohort were cored from the polyacrylamide gel, cloned, and sequenced. Unique sequences of repeated MSAP bands are reported. From the work to date, there appears to be an immediate shift of methylation patterns in embryos of Sterechinus neumayeri within 10 minutes of fertilization. Patterns between 10 minutes and 24 hours show several conserved methylation state changes at specific MSAP band locations. These data indicate that the methylation epigenetic information system is dynamic across early embryogenesis in the Antarctic sea urchin.