Dr. Jack Kennell
Associate Professor - Ph.D., University of Florida
Phone: (314) 977-3905
Fax: (314) 977-3658
Mail: Department of Biology, St. Louis University, 3507 Laclede Ave. St. Louis, MO 63103-2010
Courses: General Microbiology (464) and Microbiology Lab (465) Spring semester; Molecular Biology (470, 506): Fall semester
Educational Interests: In the past, I have incorporated Service-Learning projects in my classes and found that these projects are very effective in stimulating student interest in Biology and lead to very favorable learning outcomes. SL projects allow students to experience biology in real-world settings and offer insight into concepts that underlie biological phenomena faced by our society in ways that cannot be adequately provided in the classroom.
If you are interested in incorporating Service Learning into a biology class, please feel free to contact me. You may wish to read about some ways to implement SL projects in the following article: Educational benefits associated with Service-Learning Projects in Biology curricula. In: Life, Learning, and Community. Concepts and Models for Service-Learning in Biology. D.C. Brubaker and J.H. Ostroff, eds. American Association for Higher Education. 2000. ISBN 1-56377-018-0
Research interests: 2 major projects
- Molecular Fossils = contemporary genetic elements that are ancient in origin and can tell us about our evolutionary past. Specifically, we're interested in plasmids that replicate by reverse transcription in the mitochondria of filamentous fungi.
- Mitochondrial-Nuclear Interactions: Interested in understanding how mitochondria communicate with the nucleus in eukaryotic cells, using fungi as a model system.
- Telomere-like plasmids: This project involves the characterization of a group of novel retroplasmids found in different forma speciales of the fungal plant pathogen, Fusarium oxysporum. Plasmids pFOXC1, pFOXC2 and pFOXC3 are telomere-like linear DNA plasmids that encode a reverse transcriptase which is involved in their replication. The plasmids have a unique structure includes a hairpin at one terminus and multiple copies of a 5-bp sequence at the other termini. The plasmids are the first reported autonomously-replicating retroelements that have a linear genome and have distinctive mechanisms involved in the replication of the plasmid termini. The plasmid reverse transcriptase is found associated with the plasmid RNA in a ribonucleoprotein complex and is capable of producing full-length (-) strand cDNA products. Taken together, the pFOXC plasmids appear to be leading contenders to be related to the evolutionary precursors of the enzyme complex Telomerase and can generally be described as "molecular fossils," which are defined as contemporary genetic elements that have an ancient origin and thereby can be instructive about events in the evolutionary past. In addition to their similarities to telomerase, the plasmid replication cycle provides a mechanism by which information molecules could have been converted from single-stranded RNAs to double-stranded DNAs which could have been involved in the transition from the RNA to DNA World. Currently, our aim is to understand the mechanism of reverse transcription by using an in vitro system to study cDNA synthesis, a project which is funded by the National Science Foundation.
- Mitochondrial-Nuclear Interactions: The second project involves the use of mitochondrial plasmids as tools to study communication pathways between the mitochondria and nucleus. The biological system used in these studies involves an autonomously-replicating retroelement present in certain strains of the fungus, Neurospora crassa. The Mauriceville retroplasmid is a well-characterized circular DNA plasmid the replicates using a plasmid-encoded reverse transcriptase. The wild-type plasmid is innocuous, yet variant forms of the plasmid can arise that initiate the process of senescence, or growth cessation. My lab has been analyzing of a strain that has a very predictable rate of senescence and yet is not associated with alterations in mitochondrial DNA which are characteristic of most senescent cultures. Senescence in this strain appears to be caused by a novel mechanism that involves the inhibition of mitochondrial protein synthesis due to the over-replication of a suppressive variant of the Mauriceville plasmid. Using the senescent phenotype, they have been able to select for strains that tolerate the growth-suppressive plasmids. Data indicate that the ability of these mutants (termed long-lived strains) to withstand the growth suppressive effects of the plasmid involves a defect in the mitochondrial-nuclear communication pathway. Neurospora has proven to be a very useful organism for the study of nuclear-mitochondrial interactions since it is amenable to a variety of molecular, genetic and biochemical techniques. Our studies suggest that it will also serve as a valuable model for the study of cellular senescence, mitochondrial diseases and aging.
For more information, please see the Kennell Lab website.
Research opportunities: Several opportunities exist for graduate and undergraduate students. The project that involves the study of telomere-like retroplasmids is currently funded by NSF, and I hope to attract one or two graduate students to help characterize the novel reverse transcriptase associated with these plasmids. There are also many opportunities for undergraduate researchers, ranging from small projects that demand only a few hours a week to larger commitments that would include working (and getting paid!) during the summer months. In the past, I have had 4 to 5 undergrads in my lab at any given time and several of these students have been included as authors on one or more research publications. Students interested in learning some basic skills in Micro and Molecular biology are encouraged to write or speak with me.
Recent Publications: Walther, T.C. and J.C. Kennell. (1999) Linear mitochondrial plasmids of F. oxysporum are novel, telomere-like retroelements. Molecular Cell, 4:229-238.
Stevenson, C.B., A.N. Fox and J.C. Kennell. (2000) Senescence associated with the over-replication of a mitochondrial retroplasmid of Neurospora crassa. Mol. Gen. Genet. 263: 433-444.
Fox, A.N. and J.C. Kennell. (2001) Association between variant plasmid formation and senescence in retroplasmid-containing strains of Neurospora spp. Current Genetics, 39:92-100.