TSRC’s Town Talks: DNA, Unpredictable, Unstable Molecule that Holds the Future in its Strands

TSRC’s Town Talks: DNA, Unpredictable, Unstable Molecule that Holds the Future in its Strands

DNAInside every living cell is a long, coiled strand of DNA that contains all the information needed to make an entire organism. It’s been called the blueprint of life, but DNA sequences are hardly set in stone. In fact, they are constantly changing through natural processes such as evolution and mutation.

TSRC (Telluride Science Research Center) Town Talks introduces two scientists who study DNA dynamics: Paul Rainey, Professor of Evolutionary Genetics at New Zealand Institute for Advanced Studies, will discuss the “Evolution of Disease.” Xiaoliang Sunney Xie, Professor of Chemistry and Chemical Biology at Harvard, will present the “Single-cell Genome Sequencing: Life and Health at the Single Molecule Level.”

The talks happen Tuesday, July 30, 6 p.m., at the historic Sheridan Opera House (110 N. Oak Street).

Professor Rainey will trace the origins of disease from the time some of our ancestors believed it was caused by sin to London’s cholera outbreak to our current knowledge of microbial virulence and transmission. Rainey is particularly interested, however, in plant disease.

“With animals we understand a lot, like transmission from wild or farm animals to humans, but we have relatively no idea about the origins of plant disease.”

Take wheat rust for example, the fungus has been infecting crops for 15 years and continues to spread despite scientists’ efforts to control it.

“We tend to ignore plant disease outbreaks and focus on tuberculosis, AIDS, or malaria, but people die directly when crops fail,” said Rainey.

Rainey’s lab uses population genomics and evolutionary biology to investigate a unique pathogen that has been attacking kiwifruit since the 1980s. Parasitic elements (or “integrative conjugative elements”) are big chunks of DNA that integrate into kiwifruit’s genome. They carry with them an arsenal of disease-causing genes.

“Integrative conjugative elements share a subset of identical genes, but do not originate from the same plant clone or the same part of the world. This indicates three independent outbreaks from a single source population,” explained Rainey. “These bacteria are undergoing evolutionary change at a pace that is mind-boggling.”

Professor Xie detects genomic variations as well, but in individual human cells. His lab has developed a technique that takes a single cell, breaks it open, and sequences the entire genome in a linear, even fashion. Typically, there are two copies of a gene in each cell, but sometimes three, four, or zero gene copies can occur. These copy number variations can lead to hundreds of DNA sequence divergences. Some have no apparent effect on the organism, while others have been definitively linked to disease.

Abnormal copy number variations are common in circulating cancer cells. Xie’s lab has shown that they are actually tissue-specific. The same tumors have the same copy number patterns. He envisions creating a simple cancer diagnostic tool that can detect copy number variations in a patient’s blood sample.

Xie’s research is also focused where life begins – in the single cell, the sperm or the egg.

“We have developed pre-implantation genomic screening,” said Xie.

The process sequences “polar bodies,” the tiny cells produced with the egg cell, to detect for chromosome abnormalities.

In his talk, Xie will describe how DNA sequencing can be applied to human embryo selection for in vitro fertilization (IVF).

“Detecting chromosomal abnormalities before implantation can reduce the risk for miscarriages and genetic disorders like Down syndrome,” explained Xie.

Xie and colleagues are expecting their DNA screening method will generate an IVF baby as soon as next year.

Come to this Tuesday’s Town Talk to learn how DNA research is mitigating future crop outbreaks, defeating disease, and guaranteeing healthy babies.

For more information, visit telluridescience.org.

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