During genetic crosses between the interfertile green algae Chlamydomonas eugametos and Chlamydomonas moewusii, the I‐Ceul endonuclease encoded by the fifth group I intron (CeLSU · 5) in the C. eugametos chloroplast large subunit rRNA gene mediates the mobility of this intron by introducing a double‐strand break near the insertion site of the intron in the corresponding C. moewusii intronless allele. To characterize the biochemical properties of this endonuclease, we have purified I‐CeuI and determined the optimal reaction conditions for cleavage. I‐CeuI activity is maximal at 50°C, pH 10.0, 2.5 mM MgCl2 and in the absence of NaCl. Unlike the well‐characterized I‐SceI endonuclease, I‐CeuI remains stable following preincubation in the absence of substrate. We discuss the role that homing endonucleases may have played in the evolution of Chlamydomonas chloroplast group I introns.

Variations in copy number are the most common type of DNA structural variations. Many of these alterations are associated with disease or indicate disease susceptibility. Detection of copy number variants (CNVs) for clinical applications requires efficient, fast and cost effective methods. Here we describe the use of the NEBNext Direct® hybridization-based target enrichment method to identify somatic CNVs with high sensitivity. This approach begins with target enrichment followed by enzymatic digestion of off-target sequences and ligation of adapters that contain unique molecular identifiers (UMIs). The UMIs enhance the identification of duplicate reads and further increase the final number of on-target reads used for variant detection. We used a cell line known to contain a deletion in the CDKN2A gene and spiked DNA isolated from the cell line into a HapMap DNA sample that contains full diploid copies of CDKN2A. We were able to detect the gene deletion as a somatic CNV in a dose dependent manner with high sensitivity. Thus, we demonstrate that the NEBNext Direct approach is an efficient technique to detect somatic CNVs of high and low frequencies. Citation Format: Kruti M. Patel, Sarah K. Bowman, Noa Henig, Amy B. Emerman, Andrew Barry, Charles Elfe, Scott Adams, Salvatore Russello, Ted Davis, Cynthia L. Hendrickson. Somatic copy number variants detection using the NEBNext Direct target enrichment method [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 495. doi:10.1158/1538-7445.AM2017-495