The REU Program

Collaborative Projects: Students applying to our REU program will no doubt have divergent interests and backgrounds. Therefore, we have identified exciting collaborative project areas that fall under the umbrella heading of recognition system research and will be available for two students each. This project list is subject to change.

1. Resource Allocation and Reproduction in Colias Butterflies
   (S. Lewis & N. Tigreros)
   Most butterflies feed only as caterpillars, and during metamorphosis they must confront the herbivores' dilemma: how should they best allocate limited nitrogen to maximize their growth, survival, and reproduction? Evolutionary theory predicts that organisms will prioritize specific traits that are most directly related to fitness. This REU project will experimentally manipulate the dietary nitrogen of Colias butterflies and measure changes in resource allocation. Nitrogen allocation to different tissues will be measured for both sexes, and adult mating behavior and reproductive success will be monitored in large outdoor flight enclosures. This project combines lab and field studies that will enhance our understanding of sexual selection and the evolution of sexual size dimorphism.
    
2. Responses to stress by the honey bee (Apis mellifera)
   (P. Starks)
   Maintaining proper brood comb temperature is essential to the survival of a honey bee colony, thus the ability to recognize and respond to deviations from optimal temperatures is vital. Honey bees have been shown to augment their thermoregulatory behavior in response to abiotic (e.g., localized temperature fluctuations) and biotic (e.g., pathogens) stressors.
   1. Biotic Stress: Honey bees up-regulate brood-comb temperature in response to infestation with the heat sensitive fungal pathogen that causes chalk brood disease. The behavioral fever is preventative as A. apis is unable to significantly develop when the fever occurs. Honey bee colonies have also been shown to harbor many bacterial and fungal strains - some of which appear to be A. apis antagonists. The purpose of this REU project is to explore the preventative properties of both temperature and a fungal agent. Data gathered from these projects will potentially provide a chemical treatment for the disease.
   2. Abiotic Stress: The ability of honey bees to use their bodies as living insulation has only recently been identified. In response to localized temperature increases, worker bees shield the comb from the external heat source by positioning themselves on the hot interior region of the hive's walls. What is known of this behavior is that (1) the broodcomb is preferentially shielded over the honey-comb, (2) capped brood is preferentially shielded over uncapped brood and other cells within the brood-comb, (3) males avoid heat-shielding, and (4) bees between the ages of 12 and 14 days are significantly more likely to perform the behavior than are younger or older bees. This REU project is designed to explore thermoregulation in greater detail. Students involved in these research projects will work with animal behaviorist and an engineer to design their experiments to test specific hypotheses and gain experience in both field and laboratory work.
    
3. Characterization and identification of metamorphosisinducing factors in seawater conditioned by the marine gastropod, Crepidula fornicate
   (J. Pechenik & D. Cochrane)
   Factors (cues) that trigger metamorphosis (action) in the marine gastropod Crepidula fornicata are poorly understood. However, these animals typically metamorphose within 24 hours in response to seawater that has been conditioned by adults; that is, adults release a chemical cue(s) that stimulates their larvae to metamorphose. Recent work in our laboratories has shown that a major portion of this adult-produced metamorphosis-inducing activity can be captured by C18 μ-bondapek Sep-pak columns and eluted by 70% acetonitrile. The eluted material can be lyophilized, and the resulting material can then be stored at –0 C for prolonged periods (months) without destroying its metamorphosis-inducing activity. These results give us the remarkable opportunity to analyze this material in regard to its metamorphosis-inducing activity. This REU project will begin the characterization and identification of the active chemicals in this lyophilized material using a variety of pharmacological and biochemical approaches. Artificial seawater (ASW) will be conditioned by a known number of adults for 12 hours, applied to Sep-pak cartridges, eluted with 70 % acetonitrile, lyophilized, and reconstituted in seawater for analysis. Students will have the opportunity to work with marine biologist and a cellular physiologist to design experiments to test specific hypotheses. Students will also learn a variety of laboratory techniques in addition to aquaculture-related skills in working with the larvae of marine animals and their food supplies. Finally, students will see the many advantages of collaborating across disciplines.
    
4. The role of sensory signaling in softbodied locomotion
   (B.Trimmer, L. Dorfmann & J. Rife)
   In contrast to animals with stiff skeletons, soft-bodied animals have no easily defined joints. They can move in any plane by crumpling, rotating and bending. These movements are partly coordinated by central pattern generators but must also use information about body position (proprioception) and interactions with the environment (exteroception). It is not known how such sensory signaling is collected and incorporated into the control body of soft-bodied locomotion. This project will build on previous results from kinematic studies of the tobacco hornworm, Manduca sexta, to measure the forces exerted during multilegged crawling and to identify how such animals use sensory information during movement. Because soft-bodied animals constitute some of the most prevalent and successful terrestrial species, the results of these studies are expected to contribute to our understanding of animal movements and to the construction a new type of climbing and burrowing robot. Students involved in these research projects will work with a neuroethologist and will use a state-of the art motion analysis systems at the Tufts Biomimetic Devices Laboratory.
    
5. Transcription-coupled DNA repair and trinucleotide repeat instability in budding
   (C. Freudenreich and M. Koch)
   Maintaining genome stability is critical for every cell. Several fatal genetic diseases originate from an expansion in a trinucleotide repeat (TNR), such as the CAG repeat. TNRs can assume unusual structures, and are therefore difficult to replicate and repair. This can lead to repeat instability (expansions and/or contractions). Transcription-coupled nucleotide excision repair (TC-NER) has recently been identified as a pathway producing instability of CAG repeats. The Freudenreich lab explores instability of CAG repeats in a budding yeast model system, using an expanded CAG repeat from a human patient contained on an artificial chromosome. This REU project will involve investigating factors involved in transcription and/or TC-NER that influence CAG repeat instability. Students involved in this research project will use genetic and molecular techniques to address this research question. Using the yeast model system, this research will explore TC-NER and transcription to reveal clues about how this vital DNA repair pathway operates.
    
6. Recognition and repair of DNA double-strand breaks in Drosophila
   (M. McVey and E. Bolterstein)
   Repair of DNA lesions is critical to genome stability and cell survival. One of the most serious types of DNA damage is the DNA double-strand break. Several different pathways of break repair have been described that promote accurate rejoining of breaks and therefore prevent genomic instability. When these preferred repair pathways are compromised, the use of inaccurate repair mechanisms can lead to cellular dysfunction, cancer, and premature aging. This REU project will investigate the effects of mutation of various DNA repair genes on genome stability and overall fitness in the model metazoan Drosophila melanogaster. Undergraduates working on this project will apply both genetic and molecular techniques to gain insight into inaccurate repair mechanisms.
    
7. Effects of exotic insects on a native tree
   Sara Gómez (Post-doctoral Fellow) and Colin Orians (Professor of Biology and Director of Environmental Studies)
   The invasive hemlock woolly adelgid is causing widespread and rapid decline of eastern hemlock in North America. Despite fears that this insect would eliminate hemlocks from southern New England, mortality in this area is occurring much more slowly than predicted. It has been hypothesized that the interaction with another exotic insect, the elongate hemlock scale, could be the cause for this reduced mortality. Understanding how the interaction of invasive species changes eastern hemlock's physiology during the course of infestation is crucial in assessing the impact of these destructive pests and to establish appropriate management. More specifically, this project focuses on studying nutritional, defense-related, and biomechanical plant changes that may ultimately explain mortality or lack thereof in response to these harmful pests.
    
8. Ecology and Quality of Food and Medicinal Plant Green Roof Plots
   Selena Ahmed (Post-doctoral Fellow) and Colin Orians (Professor of Biology and Director of Environmental Studies)
   Green roofs offer vast potential to tap into limited urban space for the cultivation of useful food and medicinal plants and enhance the wellbeing of local communities. These spaces have also been shown to offer numerous other benefits including retention of storm water, lowering ambient air temperature, mitigating urban heat island effects, filtering air pollution, and providing insulation for buildings. However, green roofs have unique ecological challenges associated with limits of soil, fertilization, and water inputs. Ecological research is required to examine suitable food and medicinal plants species and combinations of plant species for thriving edible and healing green roof gardens. In addition, research is required to quantify how plant quality is affected by the harsh environmental conditions of a roof-top garden. We will be cultivating various combinations of drought-tolerant food and medicinal plants on the green roof of Tufts' Tisch library and analyzing secondary metabolite chemistry.
    
9. Impact of Climate Change on Food and Medicinal Plant Quality
   Selena Ahmed (Post-doctoral Fellow) and Colin Orians (Professor of Biology and Director of Environmental Studies)
   Changing patterns of climate variability threaten the quality of food and medicinal plants and pose a risk to producer livelihoods and consumer health. However, the mechanism and consequences of climate change on food and medicinal plant quality is largely unknown. To address this knowledge gap, we have developed an interdisciplinary research project at Tufts University with the Departments of Biology and Chemistry and Schools of Engineering and Nutrition. Our study focuses on understanding impacts of climate change on tea (Camellia sinensis (L.) Kuntze; Theaceae) and spinach (Spinacia oleracea L.; Amaranthaceae) quality via changes in secondary metabolite chemistry. We will be quantifying the effects that climate variables have on tea and spinach quality through in situ sampling coupled with experiments in climate-controlled spaces that manipulate precipitation and temperature events to those likely to occur under climate change.
    
10. The world of the woolcarder bee
    (P. Starks & K. Graham)
    The wool-carder bee, Anthidium manicatum, has a polygynous mating system featuring territorial defense by males. These males spend most of their time hovering over floral territories, waiting for females to visit in search of flowers, and violently confronting potential usurpers; beyond this, however, little is known about the behavior of this invasive bee species. This project will explore a variety of topics related to the behavioral ecology of A. manicatum, from territories as honest signals of mate quality to female mate choice to optimal foraging constraints. As such, students will have the opportunity to make significant contributions to our understanding of a largely unknown insect species. This REU project features a strong hands-on component: students will assist in the design and construction of a seminatural enclosure and will help manage a diverse collection of flowers within that enclosure. Students will also work with animal behaviorists to master basic techniques/theories of behavioral research with possible expansions into conservation and invasion biology.
     
11. Mutualistic microbes? The hidden microbial world of paper wasps
    (P. Starks & A. Madden)
    While microbes are associated with nearly every habitat on earth, most of these prokaryotes remain uncharacterized. Additionally, the relationships between multicellular organisms and their associated microbes are not well defined or understood. Of particular interest are the relationships between social insects and their associated microbes, as insects can act as vectors for pathogens and carriers of antimicrobial-producing symbionts. The objective of this project is to identify the culturable microbes associated with the two sympatric paper wasp species found in Massachusetts. Microbes will be isolated via dilution plating using numerous media recently found to increase the recoverable diversity of environmental isolates. Identity of microbes will be assessed by amplifying and sequencing a fragment of the 16S (or 18S for fungal isolates) rDNA gene and comparing them with those in the national GenBank repository. Antimicrobial production capability will be established by challenging isolates with human pathogens such as the gram negative E. coli, gram positive S. aureus, and yeast C. albicans. Students will learn how to isolate microbes from environmental samples and learn the use of molecular techniques such as PCR and DNA extraction to aid in strain identification. Students will design and use assays to aid in the characterization of these microbes as potential wasp symboints or pathogens.
     
12. Nutritional ecology of a native insect adapting to exotic invasive plant
    (F. Chew & R. Casagrande)
    The native mustard white butterfly is adapting to garlic mustard, an exotic, invasive plant that is very attractive to egg-laying female butterflies, but which kills many caterpillars. This "evolutionary trap" is mediated by the attraction of egg-laying female butterflies to plant chemicals, but the unsuitability of the plant for many of the caterpillars. More recently, there is evidence that the mustard white is evolving an escape from this "evolutionary trap." We have found that caterpillars show widely variable growth responses to garlic mustard ranging from early death (from starvation due to a feeding deterrent?) to slow growth (6 weeks versus the more usual 2.5 weeks) to rapid, robust growth. This project will collect data on nutritional assimilation indices to examine differences between families of the mustard white that appear to be completely adapted to the new plant, and others whose performance is less stellar. Some field work in Boston and western MA, some weekend work.
     
13. Latent effects of nutrition on sexual selection in cabbage butterflies
    (F.Chew & S. Lewis)
    Latent effects are experiences that occur early in an individual's life that may later affect fitness outcomes. As herbivores, cabbage butterflies assimilate as caterpillars all the nitrogen they will use as adults. For females this includes the provision of protein for egg yolks; for males this includes not only a protein-rich spermatophore given as a "nuptial gift" by the male to the female at mating, but also nitrogen for white wing pigments that are believed to contribute to a male's sexual attractiveness. This project will examine effects of limited larval nitrogen on mating behavior and follow-up on earlier experiments showing that males reared on nitrogen-deficient diets have nitrogen-poor spermatophores compared to males reared with normal levels of nitrogen in the diet. Some field work in Boston and western MA, some weekend work.
     
14. Stress responses in wild birds
    (L.M. Romero, C. Lattin & R. DeBruijn)
    We know that stress can have a multitude of bad effects, but we also know that in certain circumstances stress is beneficial, especially in relation to wild, free-living animals. This research will aim to increase our understanding of how the endocrine and physiological mechanisms underlying stress help wild animals survive stressful stimuli such as predators, storms, or anthropogenic changes. In order to explore this further, students will work with an endocrinologist, a physiologist, and an ecologist to design experiments to assess how wild birds respond to various stressful stimuli. Undergraduates will take an integrative approach to stress, focusing on neuroscience, endocrinology, and ecology. Focus will be on hypothesis testing, experimental design, and laboratory techniques (including standard endocrinological techniques including taking blood samples, hormone and receptor assays, and statistical analyses).
     
15. Genetics of Ecological Speciation
    (E. Dopman & C. Burke)
    According to the biological species concept, species arise from the evolution of barriers to gene exchange between diverging lineages. Ecological barriers, the result of ecologically-based natural selection, consist of habitat and temporal differences that limit gene exchange. The nature of ecological barriers, their genetic basis, and their impact on patterns of reproductive isolation and gene flow are largely unknown. This project will build on previous results from genetic studies of the European corn borer, Ostrinia nubilalis, to identify the molecular basis of temporal isolation. Because ecological barriers are regarded by some as among the most important forms of reproductive isolation in plants and animals, the results of these studies are expected to contribute to our fundamental understanding of the origin and maintenance of Earth's biodiversity. Students involved in these studies will work with a geneticist and will use modern physiological, computational, or molecular biology methods.
     
16. Genetics of Behavioral Speciation
    (E. Dopman & R. Burns)
    According to the biological species concept, species arise from the evolution of barriers to gene exchange between diverging lineages. Behavioral barriers include differences that lead to a lack of attraction and often arise as a result of changes in sexual signals and mate choice. The nature of behavioral barriers, their genetic basis, and their impact on patterns of reproductive isolation and gene flow are largely unknown. This project will build on previous results from genetic studies of the European corn borer, Ostrinia nubilalis, to identify the molecular basis of behavioral isolation. Because behavioral barriers are widespread among taxa, evolve rapidly, and contribute disproportionately to reproductive isolation, the results of these studies are expected to contribute to our fundamental understanding of the origin and maintenance of Earth's biodiversity. Students involved in these studies will work with a geneticist and will use modern behavioral, chemical, or molecular biology methods.
     

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