The Mendenhall lab is working to understand how stochastic or epigenetic differences in gene expression affect the manifestation of traits among isogenic animals. Consider that not all people with dominant negative oncogenes will get cancer. Also, consider that monozygotic twins live for different amounts of time. Even genetically identical animals (isogenic, as close to identical as possible) raised in homogenous environments have differences in both discrete and complex traits, including development of neoplasias and lifespan.
Dr. Mendenhall’s laboratory uses the nematode C. elegans to understand how and why genetically identical populations of cells and animals in the same environment do different things. The lab is focused on identifying cis and trans control elements that affect “noise” in gene expression. Noise in gene expression can affect the manifestation of discrete and complex traits.
This lab directly observes events inside living cells. We study the causes and consequences of variation in gene expression and differences in cell physiology. Through these studies, we are able learn specific details about the physiology of particular cells by using a spectral confocal microscope to measure the physiological properties of individual cells. Many of the different physiological states we observe in single cells may be consequential. Additionally, some of these physiological states can only be identified by quantifying the outputs of multiple processes operating in individual cells.
The Mendenhall lab uses an array of reporter genes to identify cellular mechanisms that may cause variation in complex and discrete traits. We use these reporters to measure the functionality of different cellular subsystems from the basic biology of gene expression to the structure and function of organelles. The lab is currently working on two main projects. First, the lab is focused on understanding how differences in the penetrance of Ras mutations arise, and how the neoplasias caused by Ras gain of function mutations can be suppressed. Second, the lab is also working on environmental and genetic control of allele expression bias at the protein and RNA levels.
Dr. Mendenhall’s laboratory uses the nematode C. elegans to understand how and why genetically identical populations of cells and animals in the same environment do different things. The lab is focused on identifying cis and trans control elements that affect “noise” in gene expression. Noise in gene expression can affect the manifestation of discrete and complex traits.
This lab directly observes events inside living cells. We study the causes and consequences of variation in gene expression and differences in cell physiology. Through these studies, we are able learn specific details about the physiology of particular cells by using a spectral confocal microscope to measure the physiological properties of individual cells. Many of the different physiological states we observe in single cells may be consequential. Additionally, some of these physiological states can only be identified by quantifying the outputs of multiple processes operating in individual cells.
The Mendenhall lab uses an array of reporter genes to identify cellular mechanisms that may cause variation in complex and discrete traits. We use these reporters to measure the functionality of different cellular subsystems from the basic biology of gene expression to the structure and function of organelles. The lab is currently working on two main projects. First, the lab is focused on understanding how differences in the penetrance of Ras mutations arise, and how the neoplasias caused by Ras gain of function mutations can be suppressed. Second, the lab is also working on environmental and genetic control of allele expression bias at the protein and RNA levels.
MICROSCOPY The Zeiss LSM 780 spectral point scanning confocal microscope (shown above) allows quantification of photons emitted by fluorescent proteins, which are excited by laser light. This microscope measures the emission spectrum of every point in a biological sample, allowing our lab to quantify signals from many different fluorescent proteins at once. Being able to observe more signals at once allows us to observe many processes simultaneously in individual living cells. 
GENOME EDITING VIA MICROINJECTION
One advantage of using C. elegans as a biological model system is that we have full control of the genome. 21st century genome editing afforded by transposon-based tools and the CRISPR/Cas system allows us to perform precise genetic experiments at an unprecedented pace with unprecedented precision. To do so, scientists in the Mendenhall lab inject molecular 'cocktails' directly into the oocyte-producing gonads of C. elegans hermaphrodites. |
MICROFLUIDICS The Mendenhall lab uses microfluidic technologies for both animal and cell resolution studies. Our custom-designed microfluidic devices are fabricated to immobilize animals for microscopic examination in a more limited number of orientations at animal or cell resolution. The systems also permit imaging without anesthesia at animal or cell resolution, though images must be acquired faster. Pictures of a dye-filled device, and of adult C. elegans hermaphrodites suspended in the same microfluidic device are shown above. 
ENGINEERING REPORTER GENES The Mendenhall lab uses reporter genes to investigate the molecular and cellular bases underlying causes of physiological differences in genetically identical animals. To make these reporter genes, we harness the cost-effective, and powerful capacity of yeast DNA repair machinery to assemble multiple fragments of DNA into plasmids or genome editing repair templates. These reporter genes provide information about the physiological states of cells. |