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Shawn Christensen

Name

[Christensen, Shawn]
  • Associate Professor, Department of Biology

Biography


Transposable Elements; Retroransposition

I am interested in parasitic (“selfish”) mobile genetic elements, in particular, the mechanisms by which these elements replicate and the methods by which host cells combat element replication. Mobile elements, generically called transposons, can be categorized based upon element structure and mechanism of transposition: DNA transposons, Long-Terminal-Repeat (LTR) retrotransposons, non-LTR retrotransposons (aka. LINES), and SINE elements. My lab focuses on non-LTR retrotransposons.

Non-LTR retrotransposons can have a major impact on host genomes -- over 34% of the Human genome is the result of element activity. These elements transpose through a process called Target Primed Reverse Transcription (TPRT), a process my lab studies at the biochemical level.

While biochemistry and molecular biology are my lab’s primary tools we also utilize bioinformatic and genetic approaches in our study of non-LTR retrotransposons.

Research and Expertise

  • Transposable Elements; Retroransposition
    I am interested in parasitic (“selfish”) mobile genetic elements, in particular, the mechanisms by which these elements replicate and the methods by which host cells combat element replication. Mobile elements, generically called transposons, can be categorized based upon element structure and mechanism of transposition: DNA transposons, Long-Terminal-Repeat (LTR) retrotransposons, non-LTR retrotransposons (aka. LINES), and SINE elements. My lab focuses on non-LTR retrotransposons. Non-LTR retrotransposons can have a major impact on host genomes -- over 34% of the Human genome is the result of element activity. These elements transpose through a process called Target Primed Reverse Transcription (TPRT), a process my lab studies at the biochemical level. While biochemistry and molecular biology are my lab’s primary tools we also utilize bioinformatic and genetic approaches in our study of non-LTR retrotransposons.

Publications

      Journal Article 2013
      • Shawn Christensen. Targeting target primed reverse transcription
        {Journal Article} [Refereed/Juried]
      2013
      • Rick Ricketson and Shawn Christensen‡. Targeting novel sites: NeSL-1 protease retains de-sumoylation activity.
        {Journal Article} [Refereed/Juried]

      Journal Article 2012
      • Bellah M, Christensen SM, Iqbal SM. Nanostructures for Medical Diagnostics. Journal of Nanomaterials 2012; 2012:Article ID 486301.
        {Journal Article} [Refereed/Juried]

      Journal Article 2011
      • Hariidha Shivram, Dillon Cawely, Shawn M. Christensen‡. Targeting novel sites: The N-terminal DNA binding domain of non-LTR retrotransposons is an adaptable module that is implicated in changing site specificities. Mobile Genetic Elements. 2011. 3:1-10
        {Journal Article} [Refereed/Juried]
      2011
      • Thompson B.K., Christensen S.M.‡ Independently derived targeting of 28S rDNA by A- and D-clade R2 retrotransposons: plasticity of integration mechanism. Mobile Genetic Elements. 2011; 1:29-37.
        {Journal Article} [Refereed/Juried]

      Journal Article 2010
      • Tracy,C., Rio,J., Motiwale,M., Christensen,S.M. and Betran,E. Convergently recruited nuclear transport retrogenes are male biased in expression and evolving under positive selection in Drosophila. Genetics 2010, 184, 1067-1076.
        {Journal Article} [Refereed/Juried]

      Journal Article 2009
      • Ramachandran, P. P.; Christensen, S. M.; Iqbal, S. M. Electronic detection of selective proteins using non antibody-based CMOS chip. Proceedings of IEEE-NIH, LiSSA'09 2009 (LiSSA'09), 1-4.
        {Journal Article} [Refereed/Juried]
      2009
      • Kierzek, E.; Christensen, S. M.; Eickbush, T. H.; Kierzek, R.; Turner, D. H.; Moss, W. N. Secondary structures for 5' regions of R2 retrotransposon RNAs reveal a novel conserved pseudoknot and regions that evolve under different constraints. J Mol Biol. 2009, 390, 428-442.
        {Journal Article} [Refereed/Juried]
      2009
      • Noor, M. R.; Goyal, S.; Christensen, S. M.; Iqbal, S. M. Electrical detection of single-base DNA mutation using functionalized nanoparticles. Applied Physics Letters 2009, 95 (073003).
        {Journal Article} [Refereed/Juried]

      Journal Article 2008
      • Kierzek, E.; Kierzek, R.; Moss, W. N.; Christensen, S. M.; Eickbush, T. H.; Turner, D. H. Isoenergetic penta- and hexanucleotide microarray probing and chemical mapping provide a secondary structure model for an RNA element orchestrating R2 retrotransposon protein function. Nucleic Acids Res. 2008, 36, 1770-1782.
        {Journal Article} [Refereed/Juried]

      Journal Article 2006
      • Christensen SM, Ye J, Eichbush TH. 2006. RNA from the 5' end of the R2 retrotransposon controls R2 protein binding to and cleavage of its DNA target site. PNAS.
        {Journal Article} [Refereed/Juried]

      Journal Article 2005
      • Christensen SM, Bibillo A, Eickbush TH. 2005. Role of the Bombyx mori R2 element amino-terminal domain in the target primed reverse transcription reaction. Nucleic Acids Res. 33(20):6461-8.
        {Journal Article} [Refereed/Juried]
      2005
      • Eickbush TH. 2005. R2 target primed reverse transcription: ordered cleavage and polymerization steps by protein subunits asymmetrically bound to the target DNA. Mol Cell Biol. 25(15):6617-28.
        {Journal Article} [Refereed/Juried]

      Journal Article 2004
      • Christensen, S. and Eickbush, T.H.  (2004). Footprint of the retrotransposon R2Bm protein on its target site before and after cleavage. J Mol Biol. 336(5):1035-45.
        {Journal Article} [Refereed/Juried]

      Journal Article 2000
      • Christensen, S., Pont-Kingdon, G., Carroll, D. (2000). Comparative studies of the endonucleases from two related Xenopus laevis retrotransposons, Tx1L and Tx2L: Target site specificity and evolutionary implications.  Genetica 110(3):245-56.
        {Journal Article} [Refereed/Juried]
      2000
      • Christensen, S., Pont-Kingdon, G., Carroll, D. (2000). Target specificity of the endonuclease from the Xenopus laevis non-long terminal repeat retrotransposon, Tx1L.  Mol. Cell Biol. 20(4): 1219-26.
        {Journal Article} [Refereed/Juried]

      Journal Article 1998
      • Pont-Kingdon, G., Chi, E., Christensen, S.M., and Carroll, D. (1998). RNA expression from a site-specific non-LTR retrotransposon microinjected into Xenopus oocytes.  Genetica. 104(1);67-76.
        {Journal Article} [Refereed/Juried]

      Journal Article 1997
      • Pont-Kingdon, G., Chi, E., Christensen, S.M., and Carroll, D. (1997).  Ribonucleoprotein formation by the ORF1 protein of the non-LTR retrotransposon Tx1L in Xenopus oocytes.  Nucleic Acids Research. Vol 25 No 15:3088-3094.
        {Journal Article} [Refereed/Juried]

Support & Funding

This data is entered manually by the author of the profile and may duplicate data in the Sponsored Projects section.
    • Feb 2010 to Jan 2015 Integration mechanism of site specific non-LTR retrotransposons sponsored by  - $677958

Courses

      • BIOL 1441-002 CELL AND MOLECULAR BIOLOGY

        The first of a two-part introductory biology sequence, this course focuses on the chemical and molecular basis of life, including metabolism, cell structure and function, and genetics. Laboratory experiments are designed to complement theory presented in lecture.

        Fall - Regular Academic Session - 2016 Download Syllabus Contact info & Office Hours
      • BIOL 1441-001 CELL AND MOLECULAR BIOLOGY

        Biol 1441 is the first of a two-part introductory biology sequence, this course focuses on the chemical and molecular basis of life, including metabolism, cell structure and function, and genetics. The Laboratory  experiments in the Lab associated with 1441 are designed to complement theory presented in lecture.

      • BIOL 1441-002 Cell and Molecular Biology

        Biol 1441 is the first of a two-part introductory biology sequence, this course focuses on the chemical and molecular basis of life, including metabolism, cell structure and function, and genetics. The Laboratory  experiments in the Lab associated with 1441 are designed to complement theory presented in lecture.

        Spring - Regular Academic Session - 2016 Download Syllabus Contact info & Office Hours
      • BIOL 1341-001 CELL AND MOLECULAR BIOLOGY

        Biol 1341 is the first of a two-part introductory biology sequence, this course focuses on the chemical and molecular basis of life, including metabolism, cell structure and function, and genetics.

        Spring - Regular Academic Session - 2016 Download Syllabus Contact info & Office Hours
      • BIOL 1441-002 CELL AND MOLECULAR BIOLOGY

        The first of a two-part introductory biology sequence, this course focuses on the chemical and molecular basis of life, including metabolism, cell structure and function, and genetics. Laboratory experiments are designed to complement theory presented in lecture.

        Fall - Regular Academic Session - 2015 Download Syllabus Contact info & Office Hours
      • BIOL 1441-002 Cell and Molecular Biology

        Description of Course Content (BIOL 1441): The first of a three-part introductory biology sequence, this course focuses on the chemical and molecular basis of life, including metabolism, cell structure and function, and genetics. Laboratory experiments are designed to complement theory presented in lecture. Required Textbook for Lecture: Campbell Biology, 10th Edition, by Reece and coauthors (Publisher: Benjamin-Cummings, Pearson) with the Mastering Biology online component. The cheapest way to accomplish this is to buy the electronic version of the text book along with Mastering Biology (MasteringBiology with Pearson eText -- Instant Access -- for Campbell Biology, 10th Edition $110.00 |
        ISBN-13: 978-0-321-83311-2; http://www.mypearsonstore.com/bookstore/campbell-
        biology-9780321775658?xid=PSED . For those that would rather have a paper version of the text book, the UTA bookstore has the physical text book packaged with online access to Mastering Biology. The bookstore also sells the book with no access to Mastering Biology, so pay attention to what you are buying. Do not buy the study guide sold at the UTA bookstore as Mastering Biology has the study guide material in it (and more).

        Fall - Regular Academic Session - 2014 Download Syllabus Contact info & Office Hours
      • BIOL 5334-001 Biol 5334-001

        This is a graduate course that covers the classification of transposable elements, and the mechanisms and regulation of transposition in a broad range of organisms. In addition to traditional lectures given by the instructor, students will present and discuss papers among the classic and recent literature on the topic.

        Fall - Regular Academic Session - 2013 Download Syllabus Contact info & Office Hours
      • BIOL 1441-002 Cell and Molecular Biology

        Description of Course Content (BIOL 1441): The first of a three-part introductory biology sequence, this course focuses on the chemical and molecular basis of life, including metabolism, cell structure and function, and genetics. Laboratory experiments are designed to complement theory presented in lecture. Formerly listed as BIOL 1449; credit will not be given for both.

        Fall - Regular Academic Session - 2013 Download Syllabus Contact info & Office Hours
      • BIOL 4331-001 ADVANCED MOLECULAR BIOLOGY
        No Description Provided.
        Spring - Regular Academic Session - 2013 Download Syllabus
      • BIOL 5331-001 ADVANCED MOLECULAR BIOLOGY
        No Description Provided.
        Spring - Regular Academic Session - 2013 Download Syllabus
      • BIOL 1441-002 CELL AND MOLECULAR BIOLOGY
        (BIOL 1441) The first of a three-part introductory biology sequence, this course focuses on the chemical and molecular basis of life, including metabolism, cell structure and function, and genetics. Laboratory experiments are designed to complement theory presented in lecture. Formerly listed as BIOL 1449; credit will not be given for both.
        Fall - Regular Academic Session - 2012 Download Syllabus
      • BIOL 5331-001 ADVANCED MOLECULAR BIOLOGY
        Nucleic acid biochemistry, protein-nucleic acid interactions, molecular biology, and the RNA world.
        Spring - Regular Academic Session - 2012 Download Syllabus
      • BIOL 4331-001 ADVANCED MOLECULAR BIOLOGY
        Nucleic acid biochemistry, protein-nucleic acid interactions, molecular biology, and the RNA world.
        Spring - Regular Academic Session - 2012 Download Syllabus