Scientists from J. Craig Venter Institute and Scripps Institution of Oceanography Publish Study Describing Function and Mechanisms of Diatom Centromeres

SAN DIEGO, July 6, 2017 /PRNewswire-USNewswire/ -- A research team from the J. Craig Venter Institute (JCVI) and Scripps Institution of Oceanography (SIO) have published a paper today describing the DNA sequences from the centromeres of a type of microalgae called, diatoms. The research by first author SIO's Rachel E. Diner, Ph.D., and senior author JCVI's Philip D. Weyman, Ph.D., was published in the journal Proceedings from the National Academy of Sciences (PNAS) early online edition. 

Diatoms are one of the most abundant species in aquatic environments and are often early and important indicators of the health and quality of their environment. They are also being explored for a variety of biotechnology uses including biofuels and biochemical production. Centromeres are regions in the chromosomes that are essential for cell division and cell growth in all eukaryotes. Since very little has been known about diatom centromeres, a more thorough understanding of these silica-shelled microoganisms, should enhance biological studies, including synthetic biology, and enable further development of key applications.

For this study researchers sequenced chromosomes of the model diatom, Phaeodactylum tricornutum, which has been studied extensively by some of this research team. Using a variety of methods including forward and reverse genetic approaches the team discovered 25 unique centromere sequences. They observed that diatom centromeres look very different than centromeres from land plants and animals. While land plants and animals have very long and complex sequences that define their centromeres, diatoms have very short sequences (2-3 kb) with a low content of the G and C base pairs. In fact, at least 70% of the bases in the core centromere DNA sequence were As and Ts.

The team also showed that foreign DNA from other bacteria and eukaryotes with similarly low-GC content and at least 500 bases comprising 70% A and T can mimic a diatom centromere and be maintained as artificial chromosomes.

"Most cells destroy foreign DNA to protect themselves. But in our study, we've found that if foreign DNA can mimic the cell's centromeres, it can not only avoid destruction, it can actually hijack the cell's replication machinery to create copies of itself," said Diner.

Weyman added, "DNA from bacteria may have played a large role in the evolution of diatoms. This presents fascinating hypotheses about the mechanisms by which that foreign DNA may have been acquired. Our research is continuing to add to the body of knowledge about diatoms and enables us and the research community to develop more genetic tools and applications from the enhanced understanding of these important microorganisms."

This research was supported by funds from the United States Department of Energy, the Gordon and Betty Moore Foundation, and the National Science Foundation.

About J. Craig Venter Institute

The JCVI is a not-for-profit research institute in Rockville, MD and La Jolla, CA dedicated to the advancement of the science of genomics; the understanding of its implications for society; and communication of those results to the scientific community, the public, and policymakers. Founded by J. Craig Venter, Ph.D., the JCVI is home to approximately 200 scientists and staff with expertise in human and evolutionary biology, genetics, bioinformatics/informatics, information technology, high-throughput DNA sequencing, genomic and environmental policy research, and public education in science and science policy. The JCVI is a 501 (c)(3) organization. For additional information, please visit http://www.JCVI.org.

SOURCE J. Craig Venter Institute

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