Principal Investigator


Dorothy Shippen
Phone:(979) 862-2342

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B.S. Auburn University (1982)

Ph.D. University of Alabama, Birmingham (1987)

Postdoc. University of California, Berkeley and University of California, San Francisco (1987-91)

Joined Texas A&M in 1991

Current Lab Members

 Post Doctoral Associates

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Behailu Aklilu

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Ph.D. (Genetics), 2015, University of New Hampshire, USA

M.Sc. (Agriculture and Biotechnology), 2008, Ben-Gurion University, Israel

B.Sc. (Plant Sciences), 2002, Haromaya University, Ethiopia

Research Assistant (2008-2009), Ben-Gurion University of the Negev Research Assistant (2003-2006), Ethiopian Institute of Agricultural Research

Research Interest:

The ends of eukaryotic linear chromosomes are capped by nucleoprotein structures called telomeres, which protect the termini from progressive chromosome shortening and the DNA damage response pathway. In the flowering plant, Arabidopsis thaliana, telomeres are bound by telomere specific ssDNA-binding protein complex, CST (CTC1/STN1/TEN1). The CST complex functions in both end protection and telomere replication through interactions with various proteins. In A. thaliana, it is proposed that CST engages both telomerase and DNA polymerase α (Polα) to promote G- and C-strand synthesis, respectively. My research is to investigate the dynamic in vivo interactions of CST with end protection and replication complexes. Other research interests of mine are investigating the role of A. thaliana Replication Protein A (RPA) in telomere maintenance; and Telomerase RNA Subunit 2 (TER2) in meiotic progression.

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Claudia Marcela Castillo-Gonzalez

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B.Sc. Microbiology - Minor in Chemistry, Universidad de Los Andes, Bogota D.C., Colombia (2005)

M.Sc. Microbiology, Universidad de Los Andes, Bogotá D.C., Colombia (2007)

Research Assistant, Universidad de São Paulo, São Paulo, Brazil (2009)

Ph.D. Biochemistry, Texas A&M University, College Station, Texas, USA (2017)

Post Doctoral Research Associate, Texas A&M University, College Station, Texas, USA (present) )

Research Interests:

Of the features that define a living organism, resilience is perhaps my favorite. I am deeply interested in the crosstalk of regulatory networks and chromatin modification, as means to inherit adaptive environmental information. Telomeres are the terminal structures of eukaryotic linear chromosomes, essential for maintaining genetic stability and widely regarded as the key to cell immortality. Protection of Telomeres 1(POT1) is a fundamental component of the telomere sheltering complex in mammals, whose role is to prevent the targeting of chromosome ends by the DNA repair pathway, and to modulate telomerase activity. Arabidopsis thaliana encodes three paralogs of the POT1 gene. While POT1a functions as mammalian POT1, the roles of POT1b and POT1c remain elusive. Previous work from our lab showed that POT1b acts as a negative regulator of telomerase activity, but its effect on telomere length is negligible in vivo. Loss-of-function pot1b mutants display a worsening phenotype after multiple generations, consisting of delayed development, decreased fitness, and hypersensitivity to DNA damage. We hypothesize that duplication of the POT1 gene in Arabidopsis has enabled the acquisition of specialized, non-canonical functions in POT1b. My research goal is to understand the roles of POT1b through the identification and characterization of its macromolecular complexes upon environmental stimuli.

Graduate Students


Callie Kobayashi

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B.S. in Chemistry from Sam Houston State University, Huntsville, US (2011)

Pursuing Ph.D. at Dept. of Biochemistry and Biophysics Texas A & M University, College Station, Texas (2011-present)

Research Interest:

My research focus is characterization of one of the POT1-like proteins (Protection Of Telomere), POT1c, in A. thaliana. Previous experimental results from our lab have suggested that POT1c functions in both telomerase regulation as well as telomere protection. I am using biochemical approaches to study the nucleic acid interactions of POT1c and genetic approaches to investigate its role in telomerase regulation and chromosome end protection. A second project involves the analysis of telomerase regulation in mammalian breast cancer.

Sreyashree Bose

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B.Tech (Major : Biotechnology) from West Bengal University of Technology, India (2010 - 2014)

Pursuing Ph.D. at Dept. of Biochemistry and Biophysics Texas A & M University, College Station, Texas (2014-present)

Research Interests:

Research from this lab has led to identification of three different types of RNA molecules which are involved in Telomere Biology and they are TER1, TER2 and TER2s. Among these TER2 has been seen to negatively regulate the activity of Telomerase Enzyme. Further research has shown that TER2 levels may be tuned under conditions of DNA damage indicating at the possible role of TER2 in regulating Telomerase under conditions of DNA damage. I am currently investigating the regulation of TER2 using biochemical and genetic approaches. I am also interested in studying about the pathway involved biogenesis of TER2 and involvement of TER2 in the growth and development of Arabidopsis thaliana.

Borja Barbero

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B.S in biochemistry - University of Delaware (2015)

Pursuing Ph.D at Dept. of Biochemistry and Biophysics, Texas A&M University, College Station, Texas (2015- present)

Research Interest:

Identification of function of POT1b in Arabidopsis thaliana. In humans, POT1 contributes to capping and recruitment of telomerase. Arabidopsis thaliana has evolved different POT1 genes, with different functions. As well I am interested in studying a possible collaboration between TEN1 and TER2 in the negative regulation of telomerase of Arabidopsis thaliana. A question that has intrigued me since I started working in the Shippen lab has been what recruits telomerase in arabidopsis

Jiarui Song (Gerry)

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B.S in Shandong University, China (2015)

Pursuing Ph.D. at Dept. of Biochemistry and Biophysics, Texas A and M University, College Station, Texas (2015-present)

Research Interest:

My research focus is to identify a RNA binding protein AtLa1 as a potential component involved in the Arabidopsis TER2 (Telomerase RNA 2) processing. Based on pervious study from this lab, there are three different telomerase RNAs in A. thaliana, and the non-canonical telomerase RNA- TER2 performs as negative regulator of telomerase activity. Further research has shown that AtLa1 can recognize and interact with the specific region of TER2, which suggests the hypothesis that AtLa1 is one missing component of TER2 processing or even TERs regulation. Biochemical and genetic approaches are used for identifying the telomere-related function of AtLa1. The second project is to determine whether another bona fide La protein- AtLa2 involves in the TERs maturation.

Undergraduate students

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Erica Branham

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Pursuing a B.S. in Genetics at Texas A&M University, College Station, TX (Graduation in May 2020)

Research Interest:









Elijah Canal

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Pursuing B.S. in Biochemistry at Texas A&M University, College Station, TX ( Graduate May 2019)

Research Interests:

My goal is to analyze mutants of the POT1b protein in order to understand the differences in function between POT1b and POT1a. The POT ( protector of telomeres) protein acts as a regulator of telomerase. Using side directed mutagenesis, changes in the POT1b sequence can be made then the mutant protein product can be examined and compared to the structure and function of POT1a.




Gabrielle Lessen

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B.S. in Biochemistry, Texas A&M University (Graduate in May 2018)

2015 Beckman Scholar

Research Interests:

I am an Undergraduate Biochemistry student currently working in the Shippen Lab through the Beckman Research Scholars Program. My goal is to test the lab’s working hypothesis that exchange between POT1a and TEN1 promotes the transition from extendible to non-extendable telomere states. I am testing this by investigating how CTC1, STN1, TEN1 and POT1a interact with each other and with the telomere during the cell cycle. The major goal of my project is to generate and characterize separation-of-function alleles that disrupt protein interactions within CST and telomerase to tease apart the contributions of individual telomere proteins in vivo. I am working to generate a series of mutant CTC1, STN1, TEN1 and POT1a proteins that disrupt protein-protein interactions and then to verify disruption of protein interactions in vitro. I plan to generate transgenic Arabidopsis plants that express mutant CST and POT1a proteins, to test whether disruption of CST-telomerase protein interactions alters CST and telomerase association with chromosome ends, and to investigate the biological consequences of disrupting specific CST-telomerase interactions.

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Majoring in Biochemistry and Genetics

Research Interests:

Currently we are looking at the sequences and structures of the similar proteins POT1a and POT1b. We are performing site directed mutagenesis on POT1b to make it more like the POT1a sequence in order to better understand their structures and functions. We are also generating POT1c mutants using the CRISPR-Cas9 system.


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Pursuing B.S. in Biomedical Sciences at Texas A&M University, College Station, Texas (Graduation in May 2018)

Research Interests:

My research project is to explore how Replication Protein A (RPA) is involved in telomere maintenance. A heterotrimeric single-stranded DNA binding protein, RPA plays a role in DNA replication, repair and recombination. By binding to ssDNA, it works to prevent secondary structures. Because replication at the telomeres is burdened by secondary structure formation, the role of RPA in telomere maintenance is interesting. By analyzing phenotype and telomere length across generations of mutated lines of model plant species Arabidopsis thaliana, we are investigating the function of the protein at the telomeres.



Michael Chung

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Pursuing a B.S. degree in Biochemistry at Texas A&M University (graduate May 2018)

Research Interests:

My goal is to help uncover the role of Replication Protein A (RPA) and its structural and functional homolog protein complex, CST, in telomere maintenance. We know that RPA takes part in the functions of DNA replication and repair, but it is unclear how RPA interacts with the telomeres in our model system, Arabidopsis thaliana. Specifically, I am focusing on the RPA1C subunit, and the CST complex. By manipulating the function and expression of both RPA1C and components of the CST complex, we can understand, more precisely, the function of RPA1C on the telomeres.

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Ryan Lynch

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Pursuing a B.S. degree in Biochemistry and Genetics at Texas A&M University (Graduation in May 2020)

Research Interests:

My interest is understanding the function of Replication Protein A (RPA) and its involvement in telomere maintenance. Function of RPA can be determined through genetic and phenotype measures in our model organism, Arabidopsis Thaliana.







Lauren Sampson

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Pursuing a B.S in Biochemistry at Texas A&M University (Graduation in 2020)

Research Interest:

Howdy! My research goal is to understand the function of Replication Protein A (RPA) in telomere maintenance in the research model organism, Arabidopsis thaliana. We know that RPA plays roles in DNA repair and replication, but its impact on telomere biology of higher eukaryotes is currently not clearly defined. Using reverse genetics, molecular biology, and biochemical studies, we hope to better understand the role RPA plays in telomere maintenance.






Haran Ganesh

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B.S. Biochemistry, B.S. Genetics (Graduation in May 2018)

Research Interest:

My current research focus is to identify the function of a telomere associated protein, POT1b, in Arabidopsis thaliana. Preliminary data suggest that POT1b may have a function outside telomere biology. Genetic approaches are being used in order to better understand POT1b function. My secondary research aim is to identify potential interaction partners of POT1b using biochemical approaches such as Tandem Affinity Purification and Mass Spectrometry.

understand the role RPA plays in telomere maintenance.