Histone Lys methylation plays an important role in determining chromatin states and is mostly catalyzed by SET domaincontaining proteins. The outcome, transcriptional repression or activation, depends on the methylated histone residue, the degree of methylation, and the chromatin context. Dimethylation or trimethylation of histone H3 Lys 4 (H3K4me2 or H3K4me3) has been correlated with transcriptionally competent/active genes. However, H3K4 methylation has also been implicated in gene silencing. This dualistic nature of the H3K4 methyl mark has thus far remained unresolved. In the green alga Chlamydomonas reinhardtii, Mut11p, related to a subunit of trithorax-like methyltransferase complexes, is required for transcriptional silencing. Here, we show that Mut11p interacts with conserved components of H3K4 methyltransferase machineries, and an affinity-purified Mut11p complex(es) methylates histones H3, H2A, and H4. Moreover, a Mut11 mutant showed global loss of monomethylated H3K4 (H3K4me1) and an increase in dimethylated H3K4. By chromatin immunoprecipitation analysis, this strain also displayed substantial reduction in H3K4me1 and enrichment in H3K4me2 associated with transcriptionally derepressed genes, transgenes, and retrotransposons. RNA interference-mediated suppression of Set1, encoding an H3K4 methyltransferase, induced similar phenotypes, but of lower magnitude, and no detectable increase in H3K4me2. Together, our results suggest functional differentiation between dimethyl H3K4 and monomethyl H3K4, with the latter operating as an epigenetic mark for repressed euchromatin.

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What will it take to bring about the necessary transformation of STEM higher education described in Vision and Change (2011)? PULSE (Partnership for Undergraduate Life Sciences Education) is a collaborative effort by National Science Foundation (NSF), National Institutes of Health (NIH) and Howard Hughes Medical Institute (HHMI) to stimulate systemic change within biology departments at all types of post‐secondary educational institutions, based upon the 2011 report Vision and Change in Undergraduate Biology Education and other calls for transformation of life sciences education. As life science educators we understand the change mandate (the problem). We have sought the evidence to support change (the solutions). We now must implement and institutionalize, specifically at the departmental level, these evidence‐based best practices. The PULSE Leadership Fellows are tasked with facilitating partnerships to foster change in undergraduate life science education. This poster will share the PULSE action agenda and our work to date, enhance communication with the broader scientific community and engage the American Physiological Society (APS) in the PULSE community as we cultivate change.