Title：Dissecting a transposable element burst: what is required, how has it evolved, and how does it spread?
Speaker：Susan Wessler (美國科學院院士)
Transposable elements (TEs) achieve high copy numbers through waves of amplification called bursts. For a TE to successfully burst it must be able to significantly increase its copy number without killing its host or being silenced by genome surveillance mechanisms. However, because the vast majority of TE bursts have been inferred after the fact – via computational analysis of whole genome sequence – the stealth features they require for success have remained largely undiscovered. Some features have recently been discovered by analyzing active bursts of the miniature inverted repeat transposable element (MITE) mPing and its autonomous partner Ping in four strains of domesticated rice (Oryza sativa, temperate japonica). First, mPing targets genic regions but avoids exon sequences, thus minimizing harm to the host. Second, because mPing does not share coding sequences with Ping, increases in its copy number and host recognition of its sequences do not silence Ping genes, thus allowing the continuous production of the proteins necessary to sustain the burst for decades.
Additional insights into the mPing burst come from analyses of an extensive collection of rice genomes including 3000 domesticated strains and a recombinant inbred population. While the survey of 3000 strains revealed that the burst is very recent and is restricted to a few closely related accessions, analysis of the sequences of 272 recombinant inbred lines demonstrated the potential of mPing to rapidly spread unimpeded through a large population.
Brief Introduction of Susan Wessler
Susan Wessler is Distinguished Professor of Genetics and the Neil and Rochelle Campbell Chair for Innovation in Science Education at the University of California Riverside. In 2011 she was elected Home Secretary of the U.S. National Academy of Sciences (NAS), the first women to hold this position in its 150-year history. She is a molecular geneticist known for her contributions to the field of transposon biology. A native of New York City, she received a Ph.D. in biochemistry from Cornell University (1980) and was a postdoctoral fellow at the Carnegie Institution of Washington (1980-1982). She began her career at the University of Georgia in 1983 where she remained until moving to UC Riverside in 2010.
She is the recipient of several awards including the Stephen Hales Prize (2011) from the American Society of Plant Biologists, the Excellence in Science Award from FASEB (2012) and the McClintock Prize for Plant Genetics and Genome Studies (2015). She is a member of the National Academy of Sciences (1998), the American Academy of Arts and Sciences (2007), the American Philosophical Society (2013), and a Foreign Member of the Royal Society (2017).
The seminar will be delivered in English.