Scott Holmes, associate professor of molecular biology and biochemistry, received a $5,125 National Science Foundation Research Experience for Undergraduates supplement to enhance his current grant, which supports research titled, “Epigenetic Silencing of Gene Expression in Saccharomyces Cerevisiae.”
Tag Archive for Scott Holmes
by Olivia Drake •
Scott Holmes, associate professor of molecular biology and biochemistry, received a grant worth $374,150 from the National Institutes of Health. The grant will support a study on “Functional interaction of histone H1 with the core nucleosome” until 2015. Several Wesleyan undergraduates conducted experiments crucial for developing this grant proposal, including Samantha Schilit ’10, MA ’11, who is currently in her first year as a Ph.D. candidate at the Harvard School of Medicine.
Histone proteins organize DNA into its basic organizational unit, the chromosome, and have a fundamental influence on the function of DNA. The four core histones assemble into the disc-shaped nucleosome, while the fifth histone, H1, associates with the DNA linking adjacent nucleosomes. While histone H1 is essential for life in most organisms, its specific functions remain enigmatic.
“We are using molecular genetics to examine the function of histone H1 in yeast cells, focusing on the joint contributions histone H1 and the core histones make to regulating gene expression,” Holmes explains.
by Lauren Rubenstein •
The Molecular Biology and Biochemistry Department sent three professors and six students to the international 2012 Yeast Genetics & Molecular Biology Meeting held at Princeton University recently, giving Wesleyan the largest per capita representation in the world.
Attending from the department were Associate Professor and Chair Michael McAlear and his graduate student, James Arnone; Assistant Professor Amy MacQueen and her graduate students Pritam Mukherjee and Lina Yisehak, and recent alumni Sarah Beatie ’12 and Louis Taylor ’12; and Associate Professor Scott Holmes and his graduate student, Rebecca Ryznar. All spoke or presented on various aspects of yeast genetics, molecular biology, mitosis and gene expression.
The meeting, sponsored by the Genetics Society of America and held July 31-Aug. 5, is the premier meeting for students, postdoctoral fellows, research staff, and principal investigators studying various aspects of eukaryotic biology in yeast.
by Olivia Drake •
This issue, we ask “5 Questions” of Scott Holmes, associate professor of molecular biology and biochemistry. He received a three-year grant from the National Science Foundation (NSF) to support his research on epigenetic silencing of gene expression.
Gene expression refers to the observable characteristics generated on a molecular level by a particular sequence of DNA or gene; epigenetic controls are essential in maintaining the specific patterns of gene expression that distinguish hundreds of distinct cell types in skin, muscles and other types of tissue. Epigenetic mechanisms also explain how humans can have more than 200 distinct cell types.
Q: Professor Holmes, you are an expert on genetics, molecular biology and chromosome structure. What led you to an interest in genetics and what does your lab research?
A: I had a strong affinity to genetics both as a field of study and as an experimental approach. Our DNA is present in our cells in structures known as chromosomes. My lab is addressing fundamental questions about how these structures are organized, and how that organization influences the function of genes present on the DNA. To accomplish this we primarily use genetic tools. In a directed manner we manipulate genes that we know or suspect will influence the structure of chromosomes, then assess the consequences of these changes.
Q: Last year, you received a three-year grant worth $599,832 from the National Science Foundation to support your research titled “Epigenetic Silencing of Gene Expression in Saccharomyces cerevisiae.” Please explain what epigenetic controls are and what role do they play in gene expression.
A: Most people are familiar with the basics of genetics: the DNA sequence of any two individuals varies by about 0.1 percent (about 1 in 1,000 positions in the DNA sequence), and some of that variation is manifested in measurable ways in our biochemistry, physiology, and outward appearance. Epigenetics refers to situations in which two cells or organisms have identical DNA sequences, yet establish distinct patterns of gene expression and exhibit different characteristics. Epigenetic mechanisms explain how humans can have over 200 distinct cell types despite the fact that all our cells have exactly the same DNA. The distinct gene expression patterns in these different cell types are dictated by their unique chromosome structures; we’d like to know how these structures are initially established, and then how they are inherited as cells grow and divide.
Q: What is the advantage of using Saccharomyces cerevisiae, a budding yeast, for studying gene expression?
A: Budding yeast has been used for centuries for baking and brewing;
by Olivia Drake •
For the next three years, the National Science Foundation (NSF) will support gene expression research led by Scott Holmes, associate professor of molecular biology and biochemistry.
On March 2, the NSF awarded Holmes a $599,832, three-year grant for his studies on “Epigenetic Silencing of Gene Expression in Saccharomyces cerevisiae.”
Gene expression refers to the observable characteristics generated on a molecular level by a particular sequence of DNA or gene; epigenetic controls are essential in maintaining the specific patterns of gene expression that distinguish hundreds of distinct cell types in skin, muscles and other types of tissue.
“I’m thrilled to get the funding,” Holmes says. “It’s very timely for us, and it’s a testament to the great work that graduate and undergraduate students have done in the lab over the last few years.”
Holmes, currently working with four graduate and four undergraduate students, uses a simple budding yeast, Saccharomyces cerevisiae, to study gene expression. Yeast uses an epigenetic gene repression mechanism, known as “silencing” to control the genes responsible for determining cell type.
“Two organisms, or two cells within the same organism, can have identical genetic information, or the same DNA sequence, but can have very different characteristics and functions,” Holmes explains. “We want to know how the gene expression patterns that determine cell type are first established, and then propagated as cells divide.”
The DNA in cells is organized into structures known as chromosomes. A key mechanism for controlling whether genes are on or off is by altering the structure of the chromosome. Once established, these alterations can become a stable, heritable part of the chromosome.
The nature of these structures and the manner in which they are inherited is not clear, Holmes says. Studies conducted on yeast will reveal the basic mechanisms of epigenetic inheritance.
This is the ninth year the NSF has supported Holmes’s research on yeast. He incorporates this research into the spring semester course MB&B 294, Advanced Laboratory in Genetics and Molecular Biology, which is required for undergraduate majors in the MB&B Department.
“This course is designed to familiarize undergraduates with the methods and approaches of the field in the context of pursuing novel research questions,” Holmes explains.
He also has partnered with a local high school biology teacher to devise and implement lesson plans, focusing on key concepts in genetics. Advanced students from this high school also visit the research lab to shadow graduate students.
by Olivia Drake •
Scott Holmes, associate professor of molecular biology and biochemistry, received a grant from the National Science Foundation (NSF) on March 2. The three year grant, worth $599,832, will support his studies on “Epigenetic Silencing of Gene Expression in Saccharomyces cerevisiae.”
Read more on Holmes’s study here.