Category Archives: General

Researchers Find Novel Way Plants Pass Traits to Next Generation

COLUMBUS, Ohio – New research explains how certain traits can pass down from one generation to the next – at least in plants – without following the accepted rules of genetics.

“This is the first example where somebody has been able to take an epigenetic source of variation and, through selective breeding, move it from an inactive state to an active state,” said Jay Hollick, associate professor of molecular genetics at The Ohio State University and lead author of the study. “The gene changes its expression in an epigenetic fashion and it doesn’t follow standard inheritance behaviors. Those two factors alone have pretty profound implications not only for breeding but also for evolution.”

With a longtime specialization in the molecular basis for unexpected gene activity in plants, Hollick had zeroed in on an enzyme called RNA polymerase IV (Pol IV). Multiple types of RNA polymerases are responsible for setting gene expression in motion in all cells, and Pol IV is an enigmatic RNA polymerase that is known in plants to produce small RNA molecules.

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2012-2013 Center for RNA Biology Fellowship Awards

The Center of RNA Biology announced the two 2013 RNA fellows, Paul Sample from the Alfonzo lab and Andrei Rajkovic from the Ibba lab. These students were chosen from eleven outstanding applicants. They will obtain full stipend and tuition for all of 2013 provided by the College of Arts and Sciences, the Office of Research and the College of Medicine.

Molecular geneticist receives NSF CAREER Award

R. Keith Slotkin, assistant professor, molecular genetics, just received the National Science Foundation’s highest award for the country’s most promising young scientists, the NSF CAREER Award. These grants are given to researchers who early in their careers have clearly demonstrated their potential for making significant discoveries in their fields. Slotkin studies transposable elements, sometimes called “jumping genes,” that are stretches of DNA that can duplicate or move from one location in the genome to another.

“These are fragments of DNA that reside in the genomes of multicellular organisms,” Slotkin said. “They’re not considered actual genes, but they’re like little genomic parasites. They are out only to duplicate themselves–not to help the organism they reside in.”

Their highly-successful ability to do just that has resulted in transposable elements occupying vast amounts of most plant and animal genomes. “For example, they occupy nearly half of the human genome, and 85% of corn,” Slotkin said.

In Arabidopsis thaliana, the plant that Slotkin and his students work on, transposable elements account for 20% of the genome.

Although often overlooked or dismissed as “junk DNA,” transposable elements have played an important role in the structure and evolution of these genomes.

One of the key questions is why transposable elements have been conserved through time.

“Maybe,” Slotkin said, “they have a key function in the organism. But we don’t yet know whether they are pure parasites or have another function.

“But we do know that when transposable elements are active—that is when they ‘jump,’ they cause damage, which includes chromosome breakage, instability, and disease and can destroy an organism very quickly from inside.”

It is no wonder that an organism puts a lot of its energy into suppressing or silencing transposable elements. To be successful, an organism must be able to determine which stretches of its genome are transposable elements and then shut them down.

This leads to questions of how a cell can tell transposable elements and regular genes apart and how a cell knows when to initiate silencing. The detailed molecular mechanism of how a cell determines which regions of DNA are composed of transposable elements, and how the silencing of transposable elements is initiated, are the key topics being addressed in the new NSF grant.

“Once they are silenced,” Slotkin said, “the organism is very good at keeping them silenced.

“In an animal, that silencing can be maintained only until it reproduces, because animal cells go through a re-setting process in utero.

“But in plants, this silencing can be passed down from mother to child, trans-generationally. This is not a mutation, but is epigenetic, or outside the genome; these are not changes to DNA sequence but are still inherited from cell to cell and in plants from parent-to-offspring.

“Plants offer a unique opportunity to study transposable elements,” Slotkin said. “Unlike animals, plants lack a germline that is set-aside early in embryonic development, meaning that epigenetic changes that occur during plant development are more likely to be transmitted to the next generation.

“Also plants have evolved a particularly diverse suite of mechanisms for encoding and propagating epigenetic modifications, such as forms of DNA methylation that specifically mark sites targeted by small RNA-based silencing.”

Studies into the location and timing of transposable element silencing in eukaryotes led to the identification of germ cells as the key spatial and temporal point of the lifecycle where this regulation and the initiation of transposable element silencing occurs.

Male germ cells (the equivalent of animal sperm cells) in flowering plants are housed in pollen grains. In Arabidopsis, mature pollen is a three-celled structure, containing two sperm cells embedded into a larger vegetative cell.

“Transposable element silencing is lost specifically in the pollen vegetative cell, resulting in the reactivation and mobilization of transposable elements,” Slotkin said.

“My laboratory studies transposable element epigenetic regulation at key developmental points in the plant life cycle, with particular interest in germ cells and pollen.

“We hope to discover how these mutagenic transposable elements are epigenetically repressed from generation to generation, as well as how this system has been adopted over evolutionary time to regulate non-transposable element genes,” Slotkin said.

They are asking several questions–how the cell recognizes which regions of the genome are genes and should be expressed, and which are transposable elements and shoud be selectively silenced; how epigenetic information targeting transposable elements for silencing is propogated from generation to generation, protecting each generation from new mutations; and how the recruitment of epigenetic control to transposable elements has been co-opted over evolutionary time to produce novel and interesting examples of gene regulation.

We look forward to the answers.

Physicists named American Physical Society Fellows

Physics professors Jim Beatty, Ralf Bundschuh and Yuri Kovchegov have been elected to the 2012 class of APS Fellows. Beatty has been recognized for contributions to cosmic ray astrophysics; Bundschuh for contributions to quantitative understanding of biophysical properties of nucleic acids and use of physical approaches in biological sequence analysis; and Kovchegov for contributions to understanding the structure and dynamics of strong color fields in nucleons and nuclei at high energies.

Center for RNA Biology Student Wins Awards at 2012 RNA Society Meeting

Catey Dominguez was the recipient of the National Institute of General Medical Sciences 50th Anniversary Symposium Travel Award at the 2012 RNA Society Meeting. Catey is seen posing with Dr. Douglas Black, President of the RNA Society and a Howard Hughes Medical Institute Investigator in the Department of Microbiology, Immunology, and Molecular Genetics at UCLA

CMBP Training Grant/CRB symposium a Success

Our first annual CMBP Training Grant/CRB symposium last held Tuesday was a great success thanks in large part to your enthusiastic response and participation. The talks and poster session presentations were all outstanding and we hope you enjoyed both the scientific and informal interactions throughout the day. The day was capped by the presentation by Executive Dean and Vice Provost Joseph Steinmetz to Dan Schoenberg of the first annual Excellence In RNA Biology Award for his “seminal scientific contributions and tireless efforts in establishing the Center for RNA Biology.” Congratulations Dan! Please see the attached photo.

The RNA Center Fellows (Andrea McCue, Hui-Yi Chu, Yu Zhang, Daniel Comiskey, Rebecca Williams-Wagner, Julie Dougherty, Christopher Jones, Kate Ehrensberger, Jamie Wolfe, Jonathan Picking, Sean McClory, Brian Smith) and CMBP Trainees (Ian Fleming, Tami Coursey, Brittany Suggs, Dalen Fultz, Douglas Cheung) deserve a lot of credit for the success of the symposium. In addition to presenting great talks and posters, they did an outstanding job hosting and introducing our distinguished guests and coordinating journal clubs in advance of this event.

Thanks again to Thomas Hyle and Zack Mikesell for their hard work in helping to organize this event.

2011-2012 Center for RNA Biology Fellowship Awards

The Center of RNA Biology announced the three 2012 RNA fellows, Daniel Comisky from the Chandler lab, Andrea McCue from the Slotkin lab, and Rebecca Williams-Wagner from the Henkin lab. These three students were chosen from twelve outstanding applicants. They will obtain full stipend and tuition for all of 2012 provided by the College of Arts and Sciences and the College of Medicine.