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Professor of Plant Biology
Department of Plant Biology Plant Biology Department
Selected Recent Publications; Publication List; Current Funding; Teaching; Lab Members; Lab website |
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Research
Chloroplast DNA is remarkably conservative in an evolutionary sense, with its genes governed by a slower "molecular clock" than are nuclear genes. This observation implies that the enzymes of chloroplast DNA replication and repair maintain a high level of fidelity in the maintenance of the chloroplast genome. Towards understanding the rules that govern this organelle genome, research projects in the Sears lab have investigated the controls of chloroplast DNA replication, the inheritance of chloroplasts, nuclear genes that affect the fidelity of chloroplast and mitochondrial DNA maintenance, and organelle mutation events, particularly replication slippage.
To study the mutation process, we have used the unicellular green alga Chlamydomonas reinhardtii because its small size allows billions of cells to be analyzed in a single experiment. In studying spontaneous mutations in the chloroplast DNA, we have observed a predominance of mutations resembling those that would be caused by oxidative damage. We hypothesize that under the high light growth conditions experienced by our Chlamydomonas cell lines, the chloroplast DNA repair systems may not have been able to handle all of the damage caused by the oxygen generated by the water-splitting activity of photosynthesis. We are currently testing the susceptibility of chloroplast DNA to photo-oxidative stress under various conditions, and we are seeking to determine if the high copy number of chloroplast DNA serves as a buffer to mutational damage.
In both Chlamydomonas and Oenothera (the evening primrose), we have examined the instability of chloroplast DNA microsatellites, which are composed of short direct repeated sequences. Short direct repeats are known to be prime substrates for replication slippage, which results in duplication or deletion of one or more repeats during transient dissociation of the replication complex. We have found that chloroplast microsatellites undergo mutation by duplication or deletion of repeats about 1000 times more frequently than individual nucleotides of the chloroplast DNA experience base substitution. Current studies are directed at identifying the components of the chloroplast replication and repair machinery that act to minimize both of these types of mutation.
MSU College of Natural Science
ZOL/PBL 341 - Fundamental Genetics
Every fall
GEN 810 - Theory & Practice of Teaching Genetics
Every fall
Undergraduate research projects (BMB 499, NSC 498, PLB 495)
Allison Blaine, undergraduate researcher
Ryan Mayle, undergraduate researcher
Ashita Nagori, undergraduate researcher
Kevin Raehtz, undergraduate researcher
Mike Baumgartner, undergraduate assistantback to top
Former Graduate Students:
Sara A. Kaplan
Wan-Ling Chiu
Pung-Choo Lee
Ellen M. Johnson
Mireille Khairallah
Wan-Ling Chiu
Pyung-Ok Lim
Susan Baldwin
Tseh-Ling Chang
Lara Stoike
Monica Guha-Majumdar
Elaine Palucki
Former Technicians:
Neta Holland
Gabi Schewe
Former Postdoctoral Associates:
Linda Schnabelrauch
Ruth Wolfson
Richard Glick
Karen Toth
David Jarrell
Kranthi Paladugu
Current Collaborators at MSU:
Christoph Benning, Biochemistry & Molecular Biology
Current Collaborators from outside MSU:
Andreas Weber, Heinrich Heine University of Duesseldorf
Krishna Niyogi, University of California, Berkeley
