Research Title: Fish, invertebrates, & pond ecology 

Dr. Rettig's home page 

I study the ecology of ponds and the organisms that live in ponds.  On a broad scale I am interested in examining the  fish and invertebrate community composition of small ponds in relation to variables such as pond age, pond management intensity, and the degree of development surrounding the pond.  Within a pond I examine competitive and predation-linked interactions between larval and adult bluegill sunfish and I explore the short term and long term relationship between bluegill larvae and their zooplankton prey (tiny crustaceans).  For all of these projects I can use field surveys, experiments, or a combination of both to address my research questions.

Research Title: Neural mechanism of behavior

Dr. Rhode's home page 

I am interested in understanding how neural circuits produce perceptions and behaviors. In my current research I study the vocal circuit of the African clawed frog (Xenopus laevis). Xenopus produce rhythmic vocal patterns using a type of neural circuit called a central pattern generator (CPG). CPGs are neural circuits that are capable of generating a rhythmic output without any rhythmic input; they are essentially pacemakers. They are used to control a wide variety of rhythmic behaviors in other animals, such as walking, swimming, and breathing. CPG circuits can take many forms and we don't yet understand the structure or function of the Xenopus vocal CPG, but that's one of the goals of my research. The CPG in the Xenopus vocal system is cool in a couple of ways. First, we can activate it in an isolated brain preparation to evoke rhythmic neural activity patterns called fictive vocalizations (like vocalizations without a voice). Being able to reproduce the neural patterns associated with vocalizations in an isolated brain allows us to physically and pharmacologically manipulate the neural circuit and see how it affects vocal production. Second, the Xenopus vocal circuit is altered by hormones. Male and female frogs produce different calls, and by changing hormone exposure you can change the types of vocal rhythms the brain produces. For example, giving a female testosterone will cause her to produce male-like vocal patterns. I'd like to know more about how hormones alter the neural circuits to produce these effects. I am also interested in understanding what cues naturally activate the vocal CPG to cause the animals to start calling. What external stimuli or internal hormonal cues trigger vocal behavior and how? The techniques I use in my lab include electrophysiology (recording the electrical potentials produced by one or more active neurons in brain tissue), histology (examining anatomical features of neurons), immunocytochemistry (using antibodies find the locations of neurotransmitters and other chemicals in the brain), and behavioral studies (using automated underwater microphones to monitor frog vocal behavior). If you are interested in my research, read the publications listed below and also look up papers by Ayako Yamaguchi (my former mentor) and Darcy Kelley both of whom also study the Xenopus vocal system.

Research Title: Function of insect coloration   

Dr. Schultz's home page 

My scholarship involves two areas of research involving insects: the behavioral ecology of insect coloration, and the utility of insects as indicator taxa in bio-monitoring. As a behavioral ecologist, I am interested in how specific modes of color production are adaptive in thermoregulation, anti-predator defenses and intraspecific communication. I use spectroradiometry to study how insects produce color and reflect ambient light to either contrast with the visual background and provide conspicuous signals, or to blend with background noise to become cryptic. Much of my previous work has focused on how habitat preferences influence thermoregulatory behaviors and the evolution of defensive colorations in tiger beetles. Currently, I am exploring the intraspecific signals of damselflies in the context of the light environment of their preferred habitats. I am also frequently engaged in surveying and censusing specific insects that have utility as bioindicators. These studies contribute to long-term monitoring programs of local habitats, as well as investigations of the proximate mechanisms of habitat dependence that underlie the utility of these insects as indicator taxa.

Research Title: Effects of humans on amphibians and reptiles 

Dr. Smith's home page 

As an ecologist, my research focuses on extending our understanding of how the environment, in the broadest sense of the word, can influence individuals, populations, and communities. More specifically, my research at Denison seeks to understand how human alterations of the environment can affect populations and communities, and in particular, how they are affecting amphibian populations and communities. My current research can be divided into two major project lines: 1) studies examining factors that may influence amphibian individuals, populations, and communities, and 2) studies looking at what factors may influence the distributions and abundance of terrestrial salamanders. Both project lines seek to contribute to our understanding of the basic ecology of amphibians and to our understanding of human impacts on the environment. For more information, click the link below.

Research Title: Chromatin and DNA repair    

Dr. Thompson's home page 

Eukaryotic cells contain large amounts of genetic information which must be properly packaged within the nucleus so that the DNA can be effectively utilized.  This is achieved in part by a family of highly conserved proteins known as the histones, which interact with DNA and other proteins to form material called chromatin.  Chromatin can be arranged in a variety of structural conformations, regulated in part by numerous histone post-translational modifications, which influences DNA accessibility and functionality.  My lab utilizes genetic and molecular techniques to study the ways in which histones and their modifications influence chromatin structure and function in the yeast Saccharomyces cerevisiae.  We are currently working on a series of projects to gain insight into the roles that specific histone modifications play in the processes by which DNA damage, caused by environmental factors such as ultraviolet radiation, is detected and repaired.  In addition to providing insights into fundamental cellular and molecular processes, our work has implications that extend into cancer biology and the environmental impact of solar radiation.

Research Title: Pathogenesis of Burkholderia cenocepacia   

Dr. Weingart's home page 

My interest deals with Burkholderia cenocepacia, a soil bacterium that is also an opportunistic pathogen that causes pneumonia in cystic fibrosis (CF) patients.  It has emerged as a particular concern to the CF community for three major reasons: 1) It is inherently resistant to a battery of antibiotics.  2) It is ubiquitous. 3) It is unclear how disease occurs.  Because of these characteristics it has become critical to understand this bacterium by identifying how it causes disease.  My research trajectory is to identify and examine virulence factors (i.e., the factors it uses to cause disease) in B. cenocepacia with two projects.  Project 1: When bacteria are faced with new environmental conditions they must adjust in order to survive.  Bacteria adjust by modulating the expression of specific genes so the necessary proteins are produced.  I am interested in determining the genes expressed in B. cenocepacia in response to conditions similar to the CF airways as a way to identify virulence factors.   Project 2: Two-component systems are important regulatory systems that allow bacteria to adjust to environmental conditions.  The two-component system GacS/GacA is found in some disease-causing bacteria and is involved in regulating virulence factors.  My lab is characterizing a putative GacS/GacA system in B. cenocepacia.

Research Title: Evolution of developmental mechanisms  

Dr. Romano's home page 

Transcription is regulated by non-coding sequences known as cis-regulatory elements that are usually located upstream of the protein-coding sequence, but may be located downstream of the protein-coding sequence or even within an intron.  Proteins known as transcription factors interact with these cis-regulatory elements to specify the level, timing, and spatial expression of genes.  Changes in the sequence of cis-regulatory elements, or the activity of transcription factors that interact with them, can affect the morphological outcome of development.  In fact, such changes are hypothesized to be the primary basis for differences in the anatomy, physiology, and behavior of organisms (including disease susceptibility in humans).  My research utilizes a marine invertebrate, the sea urchin, as a model system to explore the functional consequence of changes in genes and their cis-regulatory elements with regard to protein-binding affinity, patterns of gene expression in the embryo, and/or phenotype.  My long-term goal is to obtain a better understanding of the molecular basis for morphological diversity, both within and between species.

Research Title: Pathogenesis of Burkholderia cenocepacia   

Dr. Weingart's home page 

My interest deals with Burkholderia cenocepacia, a soil bacterium that is also an opportunistic pathogen that causes pneumonia in cystic fibrosis (CF) patients.  It has emerged as a particular concern to the CF community for three major reasons: 1) It is inherently resistant to a battery of antibiotics.  2) It is ubiquitous. 3) It is unclear how disease occurs.  Because of these characteristics it has become critical to understand this bacterium by identifying how it causes disease.  My research trajectory is to identify and examine virulence factors (i.e., the factors it uses to cause disease) in B. cenocepacia with two projects.  Project 1: When bacteria are faced with new environmental conditions they must adjust in order to survive.  Bacteria adjust by modulating the expression of specific genes so the necessary proteins are produced.  I am interested in determining the genes expressed in B. cenocepacia in response to conditions similar to the CF airways as a way to identify virulence factors.   Project 2: Two-component systems are important regulatory systems that allow bacteria to adjust to environmental conditions.  The two-component system GacS/GacA is found in some disease-causing bacteria and is involved in regulating virulence factors.  My lab is characterizing a putative GacS/GacA system in B. cenocepacia.

Research Title: Tumor suppression and growth factor signaling  

Dr. Yoo's home page 

Cancer occurs when a combination of DNA mutations and abnormal gene expression in a cell leads to uncontrolled growth and invasion of surrounding tissues. It is critical to understand how mutations in individual genes, or more specifically, the series of events which occur as a result of those mutations, contribute to the development of tumors. My research focuses on a gene called Pten which is one of the most commonly mutated genes in human cancer. Previous work has shown that deletion or reduction in Pten function leads to increased cell proliferation, resistance to cell death, and heightened motility and invasiveness. I am interested in identifying the molecular changes which occur when Pten is mutated, and to elucidate the signaling pathways which are affected. In particular, I am studying the mechanism by which Pten deletion leads to increased cell size and the induction of the cyclin dependent kinase inhibitor p21. As a cell biologist, I use cell culture based methods in which Pten function can be reduced through the use of RNA interference, and assay for altered gene expression in candidate downstream pathways. I am also exploring the molecular basis for why certain tissues are much more susceptible than others to tumor development as a consequence of Pten mutation.

Research Title: Chromatin and DNA repair    

Dr. Thompson's home page 

Eukaryotic cells contain large amounts of genetic information which must be properly packaged within the nucleus so that the DNA can be effectively utilized.  This is achieved in part by a family of highly conserved proteins known as the histones, which interact with DNA and other proteins to form material called chromatin.  Chromatin can be arranged in a variety of structural conformations, regulated in part by numerous histone post-translational modifications, which influences DNA accessibility and functionality.  My lab utilizes genetic and molecular techniques to study the ways in which histones and their modifications influence chromatin structure and function in the yeast Saccharomyces cerevisiae.  We are currently working on a series of projects to gain insight into the roles that specific histone modifications play in the processes by which DNA damage, caused by environmental factors such as ultraviolet radiation, is detected and repaired.  In addition to providing insights into fundamental cellular and molecular processes, our work has implications that extend into cancer biology and the environmental impact of solar radiation.

Research Title: Amphibian ecology and conservation 

Dr. Homan's home page 

My research focuses on understanding the habitat requirements of pond-breeding amphibians, as well as on expanding the ways in which effects of habitat loss can be measured and monitored. Wetlands themselves have gained some protection in recent years, however many wetland organisms, including amphibians, rely heavily on the terrestrial upland. It is crucial to the protection of native wetland species that we understand both the quantity and quality of terrestrial habitat required to support a healthy population. Many pond-breeding amphibians, particularly Ambystoma species, can live for a decade or more, and this long life span can make traditional population studies challenging. Developing alternative techniques that can supplement, or in some time sensitive cases, replace traditional population studies may aid in the relatively rapid identification of at-risk populations, as well as enable the implementation of more effective management strategies. To that end, I am currently planning several experiments including a long-term population study of a pond-breeding salamander (A. maculatum) and several studies of potential rapid assessment techniques for identifying populations at risk of severe decline or extinction at local ponds.

Research Title: Fish, invertebrates, & pond ecology

Dr. Rettig's home page 

I study the ecology of ponds and the organisms that live in ponds.  On a broad scale I am interested in examining the  fish and invertebrate community composition of small ponds in relation to variables such as pond age, pond management intensity, and the degree of development surrounding the pond.  Within a pond I examine competitive and predation-linked interactions between larval and adult bluegill sunfish and I explore the short term and long term relationship between bluegill larvae and their zooplankton prey (tiny crustaceans).  For all of these projects I can use field surveys, experiments, or a combination of both to address my research questions. 

Research Title: Effects of humans on amphibians and reptiles

Dr. Smith's home page 

As an ecologist, my research focuses on extending our understanding of how the environment, in the broadest sense of the word, can influence individuals, populations, and communities. More specifically, my research at Denison seeks to understand how human alterations of the environment can affect populations and communities, and in particular, how they are affecting amphibian populations and communities. My current research can be divided into two major project lines: 1) studies examining factors that may influence amphibian individuals, populations, and communities, and 2) studies looking at what factors may influence the distributions and abundance of terrestrial salamanders. Both project lines seek to contribute to our understanding of the basic ecology of amphibians and to our understanding of human impacts on the environment.

Research Title:  Axon guidance

Dr. Liebl's home page

I am using second-site modifier genetic screens in Drosophila to identify components of tyrosine kinase signaling pathways. Once novel genes are identified, they are characterized through classical and molecular genetic techniques.

Research Title: Evolution of developmental mechanisms 

Dr. Romano's home page 

Transcription is regulated by non-coding sequences known as cis-regulatory elements that are usually located upstream of the protein-coding sequence, but may be located downstream of the protein-coding sequence or even within an intron.  Proteins known as transcription factors interact with these cis-regulatory elements to specify the level, timing, and spatial expression of genes.  Changes in the sequence of cis-regulatory elements, or the activity of transcription factors that interact with them, can affect the morphological outcome of development.  In fact, such changes are hypothesized to be the primary basis for differences in the anatomy, physiology, and behavior of organisms (including disease susceptibility in humans).  My research utilizes a marine invertebrate, the sea urchin, as a model system to explore the functional consequence of changes in genes and their cis-regulatory elements with regard to protein-binding affinity, patterns of gene expression in the embryo, and/or phenotype.  My long-term goal is to obtain a better understanding of the molecular basis for morphological diversity, both within and between species.

Research Title:  Amphibian ecology and conservation

Dr. Homan's home page 

My research focuses on understanding the habitat requirements of pond-breeding amphibians, as well as on expanding the ways in which effects of habitat loss can be measured and monitored. Wetlands themselves have gained some protection in recent years, however many wetland organisms, including amphibians, rely heavily on the terrestrial upland. It is crucial to the protection of native wetland species that we understand both the quantity and quality of terrestrial habitat required to support a healthy population. Many pond-breeding amphibians, particularly Ambystoma species, can live for a decade or more, and this long life span can make traditional population studies challenging. Developing alternative techniques that can supplement, or in some time sensitive cases, replace traditional population studies may aid in the relatively rapid identification of at-risk populations, as well as enable the implementation of more effective management strategies. To that end, I am currently planning several experiments including a long-term population study of a pond-breeding salamander (A. maculatum) and several studies of potential rapid assessment techniques for identifying populations at risk of severe decline or extinction at local ponds.

Research Title: Plant-animal ecology and evolution  

Dr. McCall's home page

I am broadly interested in the interactions among plants and their environment and visitors.  In particular, I like to investigate questions about pollination and herbivory, or how and why some animals eat plants.

My first big question is how population identity can affect pollinator visitation and seed set in the tallgrass prairie plant Echinacea angustifolia.  I have been working with Stuart Wagenius (Chicago Botanic Garden) and Ruth Shaw (U of Minnesota) to film pollinators in Western Minnesota in hopes of quantifying how often and how long certain insects visit these plants.  Because the tallgrass prairie is a very endangered ecosystem, I hope that our findings contribute to conservation efforts there.

My second question is how and why herbivores eat flowers.  I have been interested in this question for a long time, and have been collecting data on floral damage in the California annual Raphanus sativus for many years.  Together, with my students, I am trying to tease apart why some insects like to eat different colored petals versus others and whether this corresponds to what we see in the field.

Research Title: Fish, invertebrates, & pond ecology 

Dr. Rettig's home page 

I study the ecology of ponds and the organisms that live in ponds.  On a broad scale I am interested in examining the  fish and invertebrate community composition of small ponds in relation to variables such as pond age, pond management intensity, and the degree of development surrounding the pond.  Within a pond I examine competitive and predation-linked interactions between larval and adult bluegill sunfish and I explore the short term and long term relationship between bluegill larvae and their zooplankton prey (tiny crustaceans).  For all of these projects I can use field surveys, experiments, or a combination of both to address my research questions. 

Research Title: Function of insect coloration   

Dr. Schultz's home page 

My scholarship involves two areas of research involving insects: the behavioral ecology of insect coloration, and the utility of insects as indicator taxa in bio-monitoring. As a behavioral ecologist, I am interested in how specific modes of color production are adaptive in thermoregulation, anti-predator defenses and intraspecific communication. I use spectroradiometry to study how insects produce color and reflect ambient light to either contrast with the visual background and provide conspicuous signals, or to blend with background noise to become cryptic. Much of my previous work has focused on how habitat preferences influence thermoregulatory behaviors and the evolution of defensive colorations in tiger beetles. Currently, I am exploring the intraspecific signals of damselflies in the context of the light environment of their preferred habitats. I am also frequently engaged in surveying and censusing specific insects that have utility as bioindicators. These studies contribute to long-term monitoring programs of local habitats, as well as investigations of the proximate mechanisms of habitat dependence that underlie the utility of these insects as indicator taxa.

Research Title: Effects of humans on amphibians and reptiles 

Dr. Smith's home page 

As an ecologist, my research focuses on extending our understanding of how the environment, in the broadest sense of the word, can influence individuals, populations, and communities. More specifically, my research at Denison seeks to understand how human alterations of the environment can affect populations and communities, and in particular, how they are affecting amphibian populations and communities. My current research can be divided into two major project lines: 1) studies examining factors that may influence amphibian individuals, populations, and communities, and 2) studies looking at what factors may influence the distributions and abundance of terrestrial salamanders. Both project lines seek to contribute to our understanding of the basic ecology of amphibians and to our understanding of human impacts on the environment.

Research Title: Evolution of species in Adder's Tongue ferns  

Dr. Hauk's home page 

As a plant systematist, I am interested in studying how plants evolve, and how understanding their evolutionary history can help us classify them in more meaningful ways. My research focuses on primitive ferns of the family Ophioglossaceae (adder's tongue ferns), and I use both whole organism and molecular methods. I employ DNA sequencing to help understand evolutionary relationships among species, and a PCR based technique (ISSR markers) to evaluate genetic variation within and among populations of closely related species.

Research Title: Evolution of developmental mechanisms

Dr. Romano's home page 

Transcription is regulated by non-coding sequences known as cis-regulatory elements that are usually located upstream of the protein-coding sequence, but may be located downstream of the protein-coding sequence or even within an intron.  Proteins known as transcription factors interact with these cis-regulatory elements to specify the level, timing, and spatial expression of genes.  Changes in the sequence of cis-regulatory elements, or the activity of transcription factors that interact with them, can affect the morphological outcome of development.  In fact, such changes are hypothesized to be the primary basis for differences in the anatomy, physiology, and behavior of organisms (including disease susceptibility in humans).  My research utilizes a marine invertebrate, the sea urchin, as a model system to explore the functional consequence of changes in genes and their cis-regulatory elements with regard to protein-binding affinity, patterns of gene expression in the embryo, and/or phenotype.  My long-term goal is to obtain a better understanding of the molecular basis for morphological diversity, both within and between species.

Research Focus:

Dr. Jen's home page

Specifically, my interest is in the discursive production of "public health anxieties" and the ways systems of race, nation, and gender frame "risky bodies" and "at-risk bodies." In analyzing the 2002-03 multi-country outbreak of SARS (severe acute respiratory syndrome), I trace a genealogy of SARS scientific progress at primarily cellular and genetic levels which serves as a backdrop for political, regulatory, and popular science discourses. In addition, I am currently interested in "nail salons" as discursively produced sites of "public health anxiety," fear, and contagion.

Broadly, my area of scholarship aims to make connections across terrains of “natures” and “cultures.” Much of the public perceives the biological sciences as wholly residing in the natural world. In other words, the scientific study of the living natural world operates with an objectivity that produces value-free knowledge that is untouched by “culture,” that is without historical, political and economic contexts; scientific knowledge is an unblemished reflection of the natural world. On the hand, there is an analogous and equally troublesome misconception of “women’s studies” as wholly residing in culture, that is operating within a social constructionism that problematically annihilates subjects, objects, and “facts.” While neither of these caricatures does justice to these (inter)disciplines’ intents, they allow us to trace needed connections between feminist critiques and biological inquiries. Feminist science studies aims to examine and embrace dimensions of reality between the social and the material.

Research Title: Axon guidance  

Dr. Liebl's home page

I am using second-site modifier genetic screens in Drosophila to identify components of tyrosine kinase signaling pathways. Once novel genes are identified, they are characterized through classical and molecular genetic techniques.

Research Title: Chromatin and DNA repair    

Dr. Thompson's home page 

Eukaryotic cells contain large amounts of genetic information which must be properly packaged within the nucleus so that the DNA can be effectively utilized.  This is achieved in part by a family of highly conserved proteins known as the histones, which interact with DNA and other proteins to form material called chromatin.  Chromatin can be arranged in a variety of structural conformations, regulated in part by numerous histone post-translational modifications, which influences DNA accessibility and functionality.  My lab utilizes genetic and molecular techniques to study the ways in which histones and their modifications influence chromatin structure and function in the yeast Saccharomyces cerevisiae.  We are currently working on a series of projects to gain insight into the roles that specific histone modifications play in the processes by which DNA damage, caused by environmental factors such as ultraviolet radiation, is detected and repaired.  In addition to providing insights into fundamental cellular and molecular processes, our work has implications that extend into cancer biology and the environmental impact of solar radiation.

Research Title: Pathogenesis of Burkholderia cenocepacia   

Dr. Weingart's home page 

My interest deals with Burkholderia cenocepacia, a soil bacterium that is also an opportunistic pathogen that causes pneumonia in cystic fibrosis (CF) patients.  It has emerged as a particular concern to the CF community for three major reasons: 1) It is inherently resistant to a battery of antibiotics.  2) It is ubiquitous. 3) It is unclear how disease occurs.  Because of these characteristics it has become critical to understand this bacterium by identifying how it causes disease.  My research trajectory is to identify and examine virulence factors (i.e., the factors it uses to cause disease) in B. cenocepacia with two projects.  Project 1: When bacteria are faced with new environmental conditions they must adjust in order to survive.  Bacteria adjust by modulating the expression of specific genes so the necessary proteins are produced.  I am interested in determining the genes expressed in B. cenocepacia in response to conditions similar to the CF airways as a way to identify virulence factors.   Project 2: Two-component systems are important regulatory systems that allow bacteria to adjust to environmental conditions.  The two-component system GacS/GacA is found in some disease-causing bacteria and is involved in regulating virulence factors.  My lab is characterizing a putative GacS/GacA system in B. cenocepacia.

Research Title:  Evolution of developmental mechanisms 

Dr. Romano's home page 

Transcription is regulated by non-coding sequences known as cis-regulatory elements that are usually located upstream of the protein-coding sequence, but may be located downstream of the protein-coding sequence or even within an intron.  Proteins known as transcription factors interact with these cis-regulatory elements to specify the level, timing, and spatial expression of genes.  Changes in the sequence of cis-regulatory elements, or the activity of transcription factors that interact with them, can affect the morphological outcome of development.  In fact, such changes are hypothesized to be the primary basis for differences in the anatomy, physiology, and behavior of organisms (including disease susceptibility in humans).  My research utilizes a marine invertebrate, the sea urchin, as a model system to explore the functional consequence of changes in genes and their cis-regulatory elements with regard to protein-binding affinity, patterns of gene expression in the embryo, and/or phenotype.  My long-term goal is to obtain a better understanding of the molecular basis for morphological diversity, both within and between species.

Research Title: Chromatin and DNA repair    

Dr. Thompson's home page 

Eukaryotic cells contain large amounts of genetic information which must be properly packaged within the nucleus so that the DNA can be effectively utilized.  This is achieved in part by a family of highly conserved proteins known as the histones, which interact with DNA and other proteins to form material called chromatin.  Chromatin can be arranged in a variety of structural conformations, regulated in part by numerous histone post-translational modifications, which influences DNA accessibility and functionality.  My lab utilizes genetic and molecular techniques to study the ways in which histones and their modifications influence chromatin structure and function in the yeast Saccharomyces cerevisiae.  We are currently working on a series of projects to gain insight into the roles that specific histone modifications play in the processes by which DNA damage, caused by environmental factors such as ultraviolet radiation, is detected and repaired.  In addition to providing insights into fundamental cellular and molecular processes, our work has implications that extend into cancer biology and the environmental impact of solar radiation.

Research Title: Pathogenesis of Burkholderia cenocepacia   

Dr. Weingart's home page 

My interest deals with Burkholderia cenocepacia, a soil bacterium that is also an opportunistic pathogen that causes pneumonia in cystic fibrosis (CF) patients.  It has emerged as a particular concern to the CF community for three major reasons: 1) It is inherently resistant to a battery of antibiotics.  2) It is ubiquitous. 3) It is unclear how disease occurs.  Because of these characteristics it has become critical to understand this bacterium by identifying how it causes disease.  My research trajectory is to identify and examine virulence factors (i.e., the factors it uses to cause disease) in B. cenocepacia with two projects.  Project 1: When bacteria are faced with new environmental conditions they must adjust in order to survive.  Bacteria adjust by modulating the expression of specific genes so the necessary proteins are produced.  I am interested in determining the genes expressed in B. cenocepacia in response to conditions similar to the CF airways as a way to identify virulence factors.   Project 2: Two-component systems are important regulatory systems that allow bacteria to adjust to environmental conditions.  The two-component system GacS/GacA is found in some disease-causing bacteria and is involved in regulating virulence factors.  My lab is characterizing a putative GacS/GacA system in B. cenocepacia.

Research Title:  Axon guiadance 

Dr. Liebl's home page

I am using second-site modifier genetic screens in Drosophila to identify components of tyrosine kinase signaling pathways. Once novel genes are identified, they are characterized through classical and molecular genetic techniques.

Research Title: Neural mechanisms of behavior 

Dr. Rhode's home page 

I am interested in understanding how neural circuits produce perceptions and behaviors.  In my current research I study the vocal circuit of the African clawed frog (Xenopus laevis).  Xenopus produce rhythmic vocal patterns using a type of neural circuit called a central pattern generator (CPG).  CPGs are neural circuits that are capable of generating a rhythmic output without any rhythmic input; they are essentially pacemakers.  They are used to control a wide variety of rhythmic behaviors in other animals, such as walking, swimming, and breathing.  CPG circuits can take many forms and we don't yet understand the structure or function of the Xenopus vocal CPG, but that's one of the goals of my research.

The CPG in the Xenopus vocal system is cool in a couple of ways.  First, we can activate it in an isolated brain preparation to evoke rhythmic neural activity patterns called fictive vocalizations (like vocalizations without a voice).  Being able to reproduce the neural patterns associated with vocalizations in an isolated brain allows us to physically and pharmacologically manipulate the neural circuit and see how it affects vocal production.

Second, the Xenopus vocal circuit is altered by hormones.  Male and female frogs produce different calls, and by changing hormone exposure you can change the types of vocal rhythms the brain produces.  For example, giving a female testosterone will cause her to produce male-like vocal patterns.  I'd like to know more about how hormones alter the neural circuits to produce these effects.

I am also interested in understanding what cues naturally activate the vocal CPG to cause the animals to start calling.  What external stimuli or internal hormonal cues trigger vocal behavior and how?
The techniques I use in my lab include electrophysiology (recording the electrical potentials produced by one or more active neurons in brain tissue), histology (examining anatomical features of neurons), immunocytochemistry (using antibodies find the locations of neurotransmitters and other chemicals in the brain), and behavioral studies (using automated underwater microphones to monitor frog vocal behavior).

If you are interested in my research, read the publications listed below and also look up papers by Ayako Yamaguchi (my former mentor) and Darcy Kelley both of whom also study the Xenopus vocal system.

Research Title: Neural mechanisms of behavior 

Dr. Rhode's home page 

I am interested in understanding how neural circuits produce perceptions and behaviors.  In my current research I study the vocal circuit of the African clawed frog (Xenopus laevis).  Xenopus produce rhythmic vocal patterns using a type of neural circuit called a central pattern generator (CPG).  CPGs are neural circuits that are capable of generating a rhythmic output without any rhythmic input; they are essentially pacemakers.  They are used to control a wide variety of rhythmic behaviors in other animals, such as walking, swimming, and breathing.  CPG circuits can take many forms and we don't yet understand the structure or function of the Xenopus vocal CPG, but that's one of the goals of my research.

The CPG in the Xenopus vocal system is cool in a couple of ways.  First, we can activate it in an isolated brain preparation to evoke rhythmic neural activity patterns called fictive vocalizations (like vocalizations without a voice).  Being able to reproduce the neural patterns associated with vocalizations in an isolated brain allows us to physically and pharmacologically manipulate the neural circuit and see how it affects vocal production.

Second, the Xenopus vocal circuit is altered by hormones.  Male and female frogs produce different calls, and by changing hormone exposure you can change the types of vocal rhythms the brain produces.  For example, giving a female testosterone will cause her to produce male-like vocal patterns.  I'd like to know more about how hormones alter the neural circuits to produce these effects.

I am also interested in understanding what cues naturally activate the vocal CPG to cause the animals to start calling.  What external stimuli or internal hormonal cues trigger vocal behavior and how?
The techniques I use in my lab include electrophysiology (recording the electrical potentials produced by one or more active neurons in brain tissue), histology (examining anatomical features of neurons), immunocytochemistry (using antibodies find the locations of neurotransmitters and other chemicals in the brain), and behavioral studies (using automated underwater microphones to monitor frog vocal behavior).

If you are interested in my research, read the publications listed below and also look up papers by Ayako Yamaguchi (my former mentor) and Darcy Kelley both of whom also study the Xenopus vocal system.

Research Title:  Evolution of species in Adder's Tongue ferns  

Dr. Hauk's home page 

As a plant systematist, I am interested in studying how plants evolve, and how understanding their evolutionary history can help us classify them in more meaningful ways. My research focuses on primitive ferns of the family Ophioglossaceae (adder's tongue ferns), and I use both whole organism and molecular methods. I employ DNA sequencing to help understand evolutionary relationships among species, and a PCR based technique (ISSR markers) to evaluate genetic variation within and among populations of closely related species.

Research Title: Plant-animal ecology and evolution  

Dr. McCall's home page

II am broadly interested in the interactions among plants and their environment and visitors.  In particular, I like to investigate questions about pollination and herbivory, or how and why some animals eat plants.

My first big question is how population identity can affect pollinator visitation and seed set in the tallgrass prairie plant Echinacea angustifolia.  I have been working with Stuart Wagenius (Chicago Botanic Garden) and Ruth Shaw (U of Minnesota) to film pollinators in Western Minnesota in hopes of quantifying how often and how long certain insects visit these plants.  Because the tallgrass prairie is a very endangered ecosystem, I hope that our findings contribute to conservation efforts there.

My second question is how and why herbivores eat flowers.  I have been interested in this question for a long time, and have been collecting data on floral damage in the California annual Raphanus sativus for many years.  Together, with my students, I am trying to tease apart why some insects like to eat different colored petals versus others and whether this corresponds to what we see in the field.

Research Title: Amphibian ecology and conservation

Dr. Homan's home page 

Cancer occurs when a combination of DNA mutations and abnormal gene expression in a cell leads to uncontrolled growth and invasion of surrounding tissues. It is critical to understand how mutations in individual genes, or more specifically, the series of events which occur as a result of those mutations, contribute to the development of tumors. My research focuses on a gene called Pten which is one of the most commonly mutated genes in human cancer. Previous work has shown that deletion or reduction in Pten function leads to increased cell proliferation, resistance to cell death, and heightened motility and invasiveness. I am interested in identifying the molecular changes which occur when Pten is mutated, and to elucidate the signaling pathways which are affected. In particular, I am studying the mechanism by which Pten deletion leads to increased cell size and the induction of the cyclin dependent kinase inhibitor p21. As a cell biologist, I use cell culture based methods in which Pten function can be reduced through the use of RNA interference, and assay for altered gene expression in candidate downstream pathways. I am also exploring the molecular basis for why certain tissues are much more susceptible than others to tumor development as a consequence of Pten mutation. 

Research Title: Fish, invertebrates, & pond ecology 

Dr. Rettig's home page 

I study the ecology of ponds and the organisms that live in ponds.  On a broad scale I am interested in examining the  fish and invertebrate community composition of small ponds in relation to variables such as pond age, pond management intensity, and the degree of development surrounding the pond.  Within a pond I examine competitive and predation-linked interactions between larval and adult bluegill sunfish and I explore the short term and long term relationship between bluegill larvae and their zooplankton prey (tiny crustaceans).  For all of these projects I can use field surveys, experiments, or a combination of both to address my research questions. 

Research Title: Function of insect coloration   

Dr. Schultz's home page 

My scholarship involves two areas of research involving insects: the behavioral ecology of insect coloration, and the utility of insects as indicator taxa in bio-monitoring. As a behavioral ecologist, I am interested in how specific modes of color production are adaptive in thermoregulation, anti-predator defenses and intraspecific communication. I use spectroradiometry to study how insects produce color and reflect ambient light to either contrast with the visual background and provide conspicuous signals, or to blend with background noise to become cryptic. Much of my previous work has focused on how habitat preferences influence thermoregulatory behaviors and the evolution of defensive colorations in tiger beetles. Currently, I am exploring the intraspecific signals of damselflies in the context of the light environment of their preferred habitats. I am also frequently engaged in surveying and censusing specific insects that have utility as bioindicators. These studies contribute to long-term monitoring programs of local habitats, as well as investigations of the proximate mechanisms of habitat dependence that underlie the utility of these insects as indicator taxa.

Research Title: Effects of humans on amphibians and reptiles 

Dr. Smith's home page 

As an ecologist, my research focuses on extending our understanding of how the environment, in the broadest sense of the word, can influence individuals, populations, and communities. More specifically, my research at Denison seeks to understand how human alterations of the environment can affect populations and communities, and in particular, how they are affecting amphibian populations and communities. My current research can be divided into two major project lines: 1) studies examining factors that may influence amphibian individuals, populations, and communities, and 2) studies looking at what factors may influence the distributions and abundance of terrestrial salamanders. Both project lines seek to contribute to our understanding of the basic ecology of amphibians and to our understanding of human impacts on the environment.