Dr. Krassimir Joseph Yankulov

My lab studies the epigenetic mechanisms by which chromatin regulates gene expression and DNA replication. Recently we have embarked on the analysis of how and when genes switch on and off as directed by chromatin structure. Our primary goal is to link this type of regulation to the overhaul and reassembly of chromatin after the passing of DNA replication forks. These mechanisms of gene regulation and epigenetic inheritance are highly conserved between eukaryotes. Hence, the gained knowledge spans broadly to the fields of genetic disease and cancer, to parasite immune evasion and to the adaptation of organisms to the environment. Separately, I conduct research on education and student performance in higher level university courses.

• B.Sc. - Sofia, Bulgaria
• Ph.D. - Imperial Cancer Research Fund, London, England

1. Telomeres: epigenetics, gene repression and genome plasticity.
   We use the telomeres of the yeasts S.cerevisiae as a model for the analyses of gene repression and epigenetic inheritance. Telomeres are repetitive sequences at the ends of eukaryotic chromosomes. They confer the formation of repressive chromatin structures and exert strong gene repression signals. Interestingly, the length of telomeres and their structure have been implicated in longevity and in the regulation of genome stability. In addition, the genes that are positioned close the telomeres of S.cerevisiae(and to the telomeres of many other eukaryotes) convert between repressed and active states. We call these on-off switches. Ongoing studies focus on the possible role of dormant origins of DNA replication and associated factors in the epigenetic convertibility of genes. Using this simple model organism, we are attempting to decipher general principles of gene repression and its links to DNA replication.
2. DNA replication.
   DNA replication is tightly controlled to allow exactly one round of duplication of the genome in each cell cycle. In eukaryotes, this control is exerted through factors, which confer one single firing of defined origins of DNA replication. We know reasonably well how these factors operate. However, we do not know how these factors communicate with the complex chromatin environment in the eukaryotic nuclei. We are focusing on the origins in the vicinity of telomeres to address these questions.

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• Shaban, K, Sauty, S & Yankulov, K. (2021). Variation, Variegation and Heritable Gene Repression in S. cerevisiae. Frontiers in Genetics, 12, 630506. doi:10.3389/fgene.2021.630506
• Rowlands, H, Shaban, K, Foster, B, Proteau, Y & Yankulov, K. (2019). Histone chaperones and the Rrm3p helicase regulate flocculation in S. cerevisiae. Epigenetics and Chromatin, 12(1), 56. doi:10.1186/s13072-019-0303-8
• Yankulov, K & Lu, R. (2017). On the Possibility of Preferred Performance Styles and Their Link to Learning Styles. Frontiers in Education. doi:10.3389/feduc.2017.00032
• Jeffery, D, Wyse, B, Muhammad, R, Brown, G, You, Z, Oshidari R, Masai H, Yankulov K. (2013). Analysis of epigenetic stability and conversions in Saccharomyces cerevisiae reveals a novel role of CAF-I in position-effect variegation. Nucleic Acids Research, 41(18), 8475-88. doi:10.1093/nar/gkt623
• Jeffery, D., Naoko, K., You, Z., Gharib, M., Wyse, B., Drury, E., Weireich, M., Thibault, P., Verreault, A., Masai, H., Yankulov, K. (2015). CDC28 regulates the association of Chromatin Assembly Factor I with chromatin. Cell Cycle, 14 (01), 74 - 85.
• Jeffery, D., Wyse, B., Muhammad, R., Brown, G., You, Z., Oshidari, R, Masai H, Yankulov K (2013). Analysis of epigenetic stability and conversions in Saccharomyces cerevisiae reveals a novel role of CAF-I in position-effect variegation. Nucleic Acids Research, 41 (18), 8475-88.
• Wyse, B., Oshidary, R., Jeffery, D., & Yankulov, K. (2013). Parasite epigenetics and immune evasion: lessons from budding yeast. Epigenetics & Chromatin, 19;6(1):40. doi: 10.1186/1756-8935-6-40.
• Power, P., Jeffery, D., Rehman, M. A., Chatterji, A., & Yankulov, K. (2011). Sub-telomeric core X and Y' elements in S. cerevisiae suppress extreme variations in gene silencing. PLoS ONE. 6(3):e17523. doi: 10.1371/journal.pone.0017523
• Rehman MA, Wang D, Fourel G, Gilson E, Yankulov K. Subtelomeric ACS-containing proto-silencers act as antisilencers in replication factors mutants in Saccharomyces cerevisiae. (2009) Mol. Biol. Cell 20:631-41.

Complete list

• MBG*4110 – Epigenetics
• MCB*2050 - Molecular Biology of the Cell
• MGB*2040 – Foundations in Molecular Biology and Genetics

Teaching research and publications

• Yankulov, K. (2014). More than Spelling and Grammar: Students Who Prefer to Write Outperform Students Who Prefer to Present. American Journal of Educational Research, 2(11), pp 1029-1035. DOI: 10.12691/education-2-11-5
• Jeffery, D., Yankulov, K., Crerar, A., & Ritchie, K. (2014). How to achieve accurate peer assessment for high value written assignments in a senior undergraduate course? Assessment & Evaluation in Higher Education, doi: 10.1080/02602938.2014.987721
• Yankulov, K., and Couto, R. Peer review in class: metrics and variations in a senior course. Biochem Mol Biol Educ 2012: 40, 161-168.

Graduate Students

• Ashley Fisher