Biology Projects

Projects are subject to change without notice.

Title: Identification of tetrodotoxin binding protein (TTXBP) genes in the rough skinned newt (Taricha granulosa)

Tetrodotoxin (TTX) is a potent neurotoxin found in a wide range of non-related organisms from single celled bacteria to blue ringed octopus, marine worms, salamanders, and newts.  This toxin works by blocking channels in nerve and muscle tissue, resulting in paralysis.  One species, the rough-skinned newt, Taricha granulosa, uses TTX as an anti-predator defense. Organisms that naturally harbor TTX must have a mechanism to prevent the neurotoxin from producing its negative effects like asphyxiation and death. Many species that harbor TTX are resistant to TTX due to changes in the structure of the channels TTX binds to. In addition, some TTX harboring organisms produce a protein that is capable of binding TTX. This protein is known as the TTX-binding protein (TTXBP) and has been shown to sequester TTX, protecting those species from the adverse effects of TTX.  We hypothesize that T. granulosa will possess a gene which codes for a tetrodotoxin binding protein that is similar to that of other TTX harboring organisms. This study will use a combination of molecular based methods to investigate the presence of tetrodotoxin binding protein genes in the rough-skinned newt, T. granulosa.


Title: Variation in arid-adapted legume plant responses and associations with nitrogen-fixing rhizobia bacteria

Symbiotic rhizobia bacteria have the potential to greatly alter plant traits and performance through biological nitrogen fixation. By converting atmospheric nitrogen gas (N2) into ammonia (NH3), these symbionts not only affect their plant host but can also alter the surrounding ecological community by influencing nutrient availability. However, not all species and individuals within the same species respond consistently to these interactions. In fact, my previous research has shown substantial intraspecific (within species) variation in how legumes interact with rhizobia and substantial diversity in the strains of rhizobia that associate with plant hosts across habitats. In water and nutrient limited arid environments driven by resource pulses, these interactions are expected to be especially important to partner fitness and to the surrounding community, yet remain understudied. To provide insight into the dynamics occurring between species in these important habitats, we will explore the differential plant responses to nitrogen-fixing rhizobia bacteria across and within arid-adapted legume host species, while also characterizing the diversity of rhizobia that associate with these legumes. Students will learn a mixture and field and laboratory techniques, such as: measuring plant traits and fitness to quantify the costs and benefits of these symbiotic associations; isolating and culturing bacterial strains; and performing DNA sequencing of
these isolated strains to identify the rhizobia.


Title: Virulence strategies of Gram-positive phytopathogenic bacteria

Plants are in constant interaction with microorganisms. Their surfaces and surroundings form nutrient-rich habitats for complex microbial populations that can positively or negatively influence plant health and growth. In order to gain access to a unique habitat, pathogens must overcome several challenges and it is clear that plant pathogenic bacteria are highly specialized microorganisms able to sense and adequately respond to their changing environment. Our lab focusses on soil-borne plant pathogenic bacteria. More specifically, we study the pathogenic species of the Gram-positive genera Streptomyces and Rhodococcus. The pathogenic species Streptomyces scabies, Streptomyces acidiscabies and Streptomyces turgidiscabies cause common scab on various root and tuber crops such as potato, radish and beet, while Rhodococcus fascians is responsible for leafy gall syndrome, severe malformations of the upper plant parts, to which nearly all plants are susceptible. We use various techniques ranging from common bacteriological to modern molecular and biotechnological techniques to answer fundamental and ecological questions related to bacterial communication and regulatory networks during the interaction of these bacteria and their host(s).


Title: The role of stress on tetrodotoxin production in rough-skinned newts (Taricha granulosa)

Newts of the genus Taricha have tetrodotoxin (TTX) in the glands of their skin, which is used to defend them from predation.  Tetrodotoxin is a small neurotoxin, that is most well known in puffer-fish, but is found in a wide array of other species.  Much is known about TTX in these species, but very little is known about the physiological constraints of TTX production by these species.  Stress has been shown to impact toxin/venom production in other species due to energetic costs, so it seems likely that this will also be the case in newts.  Students will learn to extract and quantify the stress hormone corticosterone in rough-skinned newts.  Further, students will learn to extract and quantify TTX in the tissues of newts.  This project will give students experience with basic lab skills like pipetting, as well as immunoassays and solid phase extraction as means of quantifying chemicals in the lab.