|Thomas Alderson||HscB, the J-protein involved in Fe-S cluster biogenesis, utilizes two bindings sites to interact with its Hsp70 chaperone
Proteins from the ISC operon of E. coli constitute the machinery used for the synthesis of iron-sulfur clusters and their delivery to recipient apo-proteins. [2Fe-2S] cluster transfer from the holo-scaffold protein IscU depends on ATP hydrolysis in the nucleotide-binding domain (NBD) of HscA, a specialized Hsp70 chaperone. HscB, an Hsp40-type co-chaperone, binds to HscA and stimulates ATP hydrolysis to promote cluster transfer. Despite the significance of HscB-mediated stimulation of ATP hydrolysis in HscA, the interactions between HscA and HscB have remained largely uncharacterized, and, moreover, the role of HscA’s interdomain linker in modulating ATPase activity has not been explored. To address these issues, we have created three variants of the isolated HscA NBD truncated at different residues within the linker, and have shown that the linker binds to the NBD and autoactivates ATP hydrolysis. Using solution-state nuclear magnetic resonance (NMR) spectroscopy and chemical shift perturbations, apo-, ADP-, and ATP-HscA binding sites were mapped onto the structure of HscB, which illustrated nucleotide-dependent binding interactions that localized to two distinct regions of HscB. These NMR data provide the first evidence of a structural role for the ubiquitously conserved J-domain residues 31-HPD-33 of HscB, which bind selectively to the ATP-bound form of HscA. Lastly, via NMR spectroscopy, we have identified and characterized a previously unreported interaction between HscA and IscA, an iron-binding protein putatively involved in [4Fe-4S] cluster transfer. Supported by NIH grants U01 GM094622 and P41 GM103399.
|Kayla McKaveney||A study of current gel electrophoresis techniques in pharmaceutical quality assessment
Pharmaceutical compounds are highly regulated throughout and following the manufacturing process. A variety of gel electrophoresis techniques can be used to evaluate the purity, potency, and stability of biopharmaceuticals in conjunction with other analytical techniques. This study explores the effectiveness and quantization limits of these highly prevalent methods.
|Miche Tong||Obesity and Volumetric/Structural Brain Differences
Obesity is the nation’s most pressing health epidemic, yet its cause and effects on the brain remain uncertain. We examined volumetric and structural differences of the brain related to body mass index (BMI). 65 adult participants (age = 27-65, BMI = 20.1-50.1) provided structural magnetic resonance images (MRI) as part of the MIDUS study (midus.wisc.edu). The brain imaging software Freesurfer (surfer.nmr.mgh.harvard.edu) was used to reconstruct gray/white matter and pial surfaces; measure cortical thickness, surface area, and folding; and compute inter-subject registration based on the pattern of cortical folds for use in both volume-based and surfaced-based analyses. The CDC’s standard BMI classifications were used to group subjects. Our findings will add to our understanding of the structural brain differences associated with obesity.
|Kelley Putt||Ultrasound Alters Bixin Pigmentation in Aqueous Solution
The use of ultrasound technology has been gaining popularity in many industries as a relatively inexpensive, simple and energy saving technique. Ultrasound induced cavitation through the generation, growth, and collapse of large bubbles liberates high energy. When water is exposed to this high energy, the cavitation phenomenon generates highly reactive hydroxyl and hydrogen species. This study investigated the efficacy of ultrasound technology in reducing pigment intensity of bixin in aqueous solution. The cavitation phenomenon and resulting generation of reactive water species was hypothesized to alter the chemical structure of the bixin molecule, thus reducing pigment intensity.
The pigment annatto was studied because of its importance in applications such as whey bleaching. Annatto extract was added in various amounts (1, 2, 3 mL) to 12 L of distilled water. The solution was pumped through a closed ultrasound system, and samples were taken at designated intervals. Spectrophotometric methods were used to determine the degree of color intensity. The effectiveness of ultrasound was compared to chemical means of annatto bleaching. Anthocyanin and Beta-Carotene pigments were also exposed to the same treatments.
When exposed to ultrasound, the annatto pigment intensity was significantly diminished. A logarithmic relationship was found to exist between absorbance and exposure time. After the 60 minute experimental time frame, the degree of bleaching was 53%. The rate of bleaching was found to be 196 minutes. This can be compared to the control, which exhibited only 6% bleaching, with a 6415 minute rate. Chemical treatment resulted in a 98% degree of bleaching, with an 8 minute rate, while the combined strength of chemical and ultrasound exposure produced a 99% degree of bleaching and a 6 minute rate. For the other pigments investigated, the bleaching effects were less significant.
|Patrick Carney||5-Fluorouracil Effect on Colon Cancer Cells in Response to Aryl Hydrocarbon Receptor Expression in vitro
The aryl hydrocarbon receptor (AhR) is a ligand dependent transcription factor that acts as either an oncogenic pathway or tumor suppressive mechanism in human cancers, depending on cell and tissue type. The exact mechanism of AhR in colorectal cancer is unknown, but many common chemopreventatives activate the AhR pathway. The aryl hydrocarbon receptor activates a battery of cytochrome p450 surrogates, which play a major role in the metabolism of exogenous toxins and drugs, such as chemotherapeutic agents. CYP enzymes in particular are implicated in chemotherapeutic metabolism. We hypothesize that decreased expression of the aryl hydrocarbon receptor regulates the activity of anti-cancer agents such as 5-Fluorouracil (5-FU) in colon tissue in vitro through the activation or deactivation of its downstream gene surrogates, in particular P450 isozymes. We will use normal HCT 116 cells and HCT 116 cells transfected for low AhR expression, then treat them with 5-FU to determine the drug’s efficacy in AhR knockdown cells vs normal cells. We will also analyze the levels of downstream AhR enzymes implicated in chemotherapeutic pharmacokinetics. These studies will allow us to analyze the impact of the aryl hydrocarbon receptor in the metabolism of chemotherapeutic drugs and better understand its role in chemoresitance.
|Chin Leng Cheng||Characterization of the Noncanonical RNA Ligase RtcB
RNA ligases are vital enzymes responsible for biological processes such as RNA repair and tRNA maturation. RNA ligase RtcB has been identified as an enzyme that catalyzes the GTP-dependent ligation of 3′-P and 5′-OH RNA termini. The ligation reaction of RNA ligase RtcB proceeds in a three-step mechanism involving the binding of cofactor GTP to RtcB, the subsequent transfer of cofactor to the 3′-P of RNA and finally the ligation of RNA. Recently, we discovered another component of the ligation reaction, Archease, an activator that increases RNA ligation catalyzed by Pyrococcus horikoshii RtcB. In addition, we found that Archease expands the cofactor specificity of RtcB, allowing RtcB to also use ATP, dGTP, and ITP as cofactors. Through enzymatic assays, kinetic and structural studies, we provided mechanistic insight into RNA ligation catalyzed by the noncanonical RtcB and showed that RtcB and Archease indeed function collectively.
|Taylor Keding||Functional Neural Correlates of Emotion Regulation in Pediatric Post-traumatic Stress Disorder
Studies on adult post-traumatic stress disorder (PTSD) suggest abnormalities in emotion regulation brain circuitry, including increased amygdala, insula, and dorsal anterior cingulate cortex (ACC) activation and decreased ventromedial prefrontal cortex (PFC) activation in response to emotional stimuli. However, few studies have investigated the neural correlates of emotion regulation and developmental trajectory associated with pediatric PTSD. Twenty-eight non-traumatized healthy youth and 25 medication-free youth with PTSD completed fMRI while performing an implicit emotion regulation task. Subjects identified a color overlying a morphing emotional face (angry or happy) or shape across three blocks. Statistical analysis was performed in AFNI using group, condition, block, and age as factors, with sex included as a covariate of no interest. A priori search regions included the medial PFC and amygdala-hippocampus with multiple comparison corrections applied. Across emotion conditions, there were significant group x age interactions in the right amygdala, right frontal pole of the PFC (BA 10), and left rostral ACC (BA 32). In the amygdala and rostral ACC, the PTSD group showed increasing activation with age relative to decreasing activation with age in controls. The opposite trend was seen in the frontal pole. There was also a significant condition x group interaction in the bilateral dorsal ACC (BA 32). There were no group differences in the angry-shape contrast; however, in happy-shape, the PTSD group showed hyperactivation relative to the control group. These findings suggest that pediatric PTSD is associated with abnormal recruitment and development of prefrontal and limbic regions in the brain. Decreased activation in the PFC and increased activation in the amygdala and ACC may represent an altered trajectory in the development of healthy emotion regulation circuitry.
|Elizabeth Boots||Cardiorespiratory fitness is associated with brain structure, cognition, and mood in a middle-aged cohort at risk for Alzheimer’s disease
Background: Cardiorespiratory fitness (CRF) is an objective measure of habitual physical activity. The gold standard method for measuring CRF is graded exercise testing (GXT), but GXT is not feasible in many settings. The objective of this study was to examine whether a non-exercise estimate of CRF is related to gray matter (GM) volumes, white matter hyperintensities (WMH), cognition, objective and subjective memory function, and mood in a middle-aged cohort at-risk for Alzheimer’s disease (AD).
Methods: 315 cognitively-healthy adults (age=58.58 ± 6.33 years) enrolled in the Wisconsin Registry for Alzheimer’s Prevention participated in this study. Participants underwent structural MRI scanning, comprehensive cognitive testing, anthropometric assessment, venipuncture for laboratory tests associated with vascular risk, and a self-report physical activity (PA) questionnaire. CRF was calculated using a previously-validated equation incorporating sex, age, body-mass index, resting heart rate, and self-reported PA. FreeSurfer was used to derive GM volumes from AD-related regions of interest (ROIs), and WMH were quantified using the Lesion Segmentation Toolbox. We assessed correlations between the CRF measure and known lab- and anthropometry-based indices of cardiovascular risk. Linear regression, adjusted for relevant covariates, was used to examine relationships between CRF, GM volumes, and WMH. Pearson correlations were used to assess associations between CRF and self- and informant-reported memory complaints, and depressive symptoms.
Results: The CRF measure was negatively correlated with several cardiovascular risk factors including central adiposity (p<.001), systolic blood pressure (p=.001), and interleukin-6 (p=.002). Higher CRF was associated with greater GM volumes in several ROIs including the hippocampus (p=.010), amygdala (p=.026), precuneus (p=.033), supramarginal gyrus (p<.001), and rostral middle frontal gyrus (p=.028). Increased CRF was also associated with lower WMH (p<.001) and better cognitive performance in Verbal Learning & Memory (p=.022), Immediate Memory (p=.002), Speed & Flexibility (p=.033), and Visuospatial Ability (p<.001). Lastly, CRF was negatively correlated with self- and informant-reported memory complaints (p’s=.045 and.032, respectively), and depressive symptoms (p=.017).
Conclusions: Higher CRF is associated with increased brain volume, reduced white matter lesions, better cognitive abilities and mood, and fewer memory complaints. This suggests that habitual participation in physical activity may provide protection for brain structure and cognitive function, thereby decreasing future risk for AD.
|Peter Reiter||The influence of acute stroke on verbal working memory and cortical thickness
Several studies have investigated the influence of healthy aging and disease on working memory and cortical thickness. We investigated the influences of acute stroke on verbal working memory performance and cortical thickness. The experimental group was composed of patients with acute lesions (less than 7 days from stroke: N=18, male=12, female=6: average age=58 years: handedness right=16, left=2: lesion type cortical=14, subcortical=2, cerebral=2: lesion side right=6, left=11, both=1) and the control groups were healthy individuals with no history of neurological or psychiatric illness divided into young (30 years of age or younger: N=14, male=7, female=7: average age=23 years: handedness right =12, left=2) and old groups (40 years of age or older: N=12, male=5, female=7: average age=53 years: handedness right=12). Groups were tested on working memory through the digit span backward and forward test and a computerized verbal working memory test. Anatomical scans were collected on all subjects, which then were used to calculate cortical thickness via Freesurfer analysis. There was a significant difference between stroke patients and young controls on both measures of digit span and encoding and retrieval times on the working memory task (p<.01). A significant difference for all these measures was seen between stroke patients and old controls (p<.05). Results are discussed in terms of changes in cognition following stroke and correlation with stroke characteristics and brain plasticity changes.
|Meghan Turner||Attack Mechanism of the Antimicrobial Peptide Indolicidin on the Cytoplasmic Membrane of E. coli
The current antibiotic-resistance epidemic has led to increased focus on antimicrobial peptides (AMPs) as potential prototypes for the design of novel antibiotics. AMPs are short peptides that form a part of the natural immune defense system of multi-cellular organisms. Bulk biochemical assays have helped elucidate possible mechanisms by which these AMPs kill bacteria. In bulk studies, however, it is difficult to observe the sequence of events due to limited spatial and temporal resolution. Single cell, time-lapse fluorescence microscopy was used to study the attack of the AMP indolicidin on E. coli. Mutant deletion strains help determine the importance of mechanosensitive channels for membrane translocation of AMPs, the halting of cell growth, and cell survival. We hope to provide a detailed mechanistic explanation of the attack of indolicidin on the membrane system of E. coli to further improve designs of synthetic AMPs for use as alternatives to antibiotics.
|Erica Christensen||THE TCDD INDUCED ACTIVATION OF ARYL HYDROCARBON RECEPTOR (AHR) CREATES NEUROVASCULAR MALFORMATIONS
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a persistent environmental contaminant that exerts toxicity by activating aryl hydrocarbon receptor (AHR) signaling. AHR is a ligand-activated transcription factor that dimerizes with aryl hydrocarbon receptor nuclear translocator (ARNT) and binds to sequences known as aryl hydrocarbon receptor response elements (AHREs) upstream of target genes such as cytochrome P450, CYP1A.We wanted to see the impact TCDD and AHR had on neurovascular development. We have found malformations in the brain and its vasculature following activation of AHR by TCDD . Due to a genome duplication event, zebrafish have two AHRs, AhR1 and AhR2. To determine whether AHR 1+2 are important for normal zebrafish neurovascular development we used morpholino oligonucleotides (MOs) to block translation of AHR1+2 in zebrafish embryos We have found vascular malformations in embryos injecting AhR1 and AhR2 indicating that AhR 1 and AhR 2 are needed for normal zebrafish development. Proper brain vascularization is necessary for brain health and functioning.
|Wen Fu||Characterizing ?PR promoter DNA wrapping around E.coli RNA polymerase by fluorescence
Transcription is the first step in gene expression and regulation and plays an important role in cellular function. In the initial steps of transcription, RNA Polymerase (RNAP), after recognizing and binding the -10/-35 elements of promoter DNA, works as molecular isomerization machine to bend the downstream duplex into the cleft and open 13 base pairs (bp) to form an ‘open promoter complex’, RPo (Saecker et al., 2011). Cutting off DNA upstream of -65 slows that process of putting the downstream duplex in the cleft and opening it by an order of magnitude. Far upstream DNA is needed for efficient insertion of downstream DNA in the cleft (Davis et al., 2007). I propose to test the hypothesis that this upstream DNA wraps an RNA polymerase, and that upstream wrapping opens a gate in the downstream cleft to allow DNA to enter. To test this proposal, I will use equilibrium Fluorescence Resonance Electron Transfer (FRET) experiments on a strong promoter, ?PR, with fluorescent dyes on the upstream and downstream ends of the DNA. In order to study the DNA wrapping kinetics during transcription initiation, I will perform FRET experiment on the stopped flow fluorimeter. For future extended project, different promoters other than ?PR, such as T7A1 promoter DNA, will be used.
|Ryan Prestil||Creation of novel human pluripotent stem cell lines using RNA-guided gene editing
In order for human pluripotent stem cells to fulfill their promise of revolutionizing modern medicine and biology, it is essential that the genetic code be controlled precisely, easily, and effectively. The recently-discovered Cas9 nuclease utilizes a short segment of guide RNA complementary to a target genomic locus to induce highly specific double-stranded DNA cuts. The ability to direct custom mutations and insert reporters or gene circuits could pave the way for stem cell-based disease modeling, tissue engineering, and personalized therapies. After optimizing the protocol necessary to deliver the Cas9 nuclease and donor vector into the cell, we have created several original cell lines with a fluorescent marker on nuclear histone 2B, known has H2B-mCherry. These lines will be used to elucidate the effects of nuclear shape on fibroblast reprogramming efficiency and the subcellular mechanisms underpinning differentiation to various mature cell types.
|Emily Weber||Functional characterization of an antimicrobial protein from plants
Various plant species have an array of proteins and other macromolecules naturally occurring on their leaf surfaces that impart resistance to disease-causing pathogens. The DNA sequences of many of these proteins have been elucidated, but it has not yet been determined which structural motifs (or sections) of the proteins are responsible for their biological functions or if the entire sequence is necessary. We propose to determine whether or not truncated portions of a novel antimicrobial protein from Nicotiana tabacum expressed in a heterologous system can maintain their inhibitory function against plant pathogens. Specifically, we will truncate the genetic sequence coding for candidate-X, our novel antimicrobial protein, into two distinct derivatives, express them the yeast Kluyveromyces lactis (K. lactis), our heterologous system, and test for antimicrobial function in comparison with the full-length protein. We assigned specific sites for truncation along the DNA sequence and used polymerase chain reaction (PCR) to amplify the molecular constructs for introduction into K. lactis. Successful expression of a shortened genetic sequence that maintains its original function may ultimately improve the efficiency of laboratory- produced proteins and could be utilized in a variety of agricultural applications.
|Cal Melberg||Hedgehog signaling perturbation in the mouse: Phenotypic characterization of craniofacial malformations
The Hedgehog (Hh) signaling pathway is a critical molecular mediator of embryogenesis, including development of the brain, face, and limbs. Genetic and chemical disruption of the Hh pathway has been associated with numerous structural malformations including holoprosencephaly (HPE) and cleft lip and/or palate (CL/P) but how disruption of a single pathway can cause such distinct outcomes is presently unclear. By administering a potent pathway antagonist to timed-pregnant mice, we have shown that acute pathway inhibition recapitulates this spectrum, with the specific outcome dependent upon precise timing of exposure. Here, I propose to use a battery of techniques, including careful dissection, bone and cartilage, and hematoxylin and eosin staining, to methodically phenotype control and Hh antagonist exposed mouse fetuses. This represents the continuation of a project in which I have been intimately involved and will provide me the opportunity to learn new techniques, analyze data, and present my findings. The proposed project is also integrated into the broader research arc of our laboratory and promises to advance our efforts to better understand how genetic and chemical factors interact in the genesis of common and morbid human birth defects.
|Tianxiao Han||Characterization of the Effects of TraR, a Regulator of Ribosome Biosynthesis, in Escherichia Coli.
acteria survive various stresses, such as, entry into stationary phase, carbon starvation, and phosphate starvation, by modulating gene expression that alters metabolic output. During stress, the protein DksA and co-regulator guanosine tetraphosphate repress ribosomal RNA (rRNA) transcription, which consequently slows growth. Bioinformatic analysis identified the small protein, TraR, as a distant homolog of DksA. Blankschien et al., 2009 determined that, like DksA, TraR downregulates rRNA transcription. We aim to understand the mechanism of such downregulation. Our preliminary experiments suggest that TraR cloned into a plasmid construct is a valid experimental tool for analyzing the effect of wild-type TraR on rRNA transcription. Our future goal is to conduct site-directed mutagenesis on cloned TraR to identify critical amino acid residues that contribute to its structure and/or function.
|Monica Chou||Delayed aging in a pill: metabolic analysis of caloric restriction mimetics in mice.
It has been firmly established that caloric restriction (CR), a dietary intervention involving the reduction in caloric intake without malnutrition, delays aging and the onset of age-associated diseases. This effect is highly evolutionarily conserved. A better understanding of the mechanisms of CR will provide a unique perspective on the aging process. With this knowledge, pharmacological interventions can be designed to mimic CR’s mechanisms where health benefits of CR may be realized without reducing caloric intake by simply taking a pill. Work in the Anderson lab has shown that energy metabolism is central to CR’s ability to delay aging. Three drugs that target regulators of energy metabolism have been identified as potential CR mimetics: lithium carbonate, bezafibrate, and resveratrol. For all three drugs the direct or indirect target is PGC-1a (peroxisome proliferator activated receptor gamma co-activator 1 alpha), a master regulator of energy metabolism. The objective of this proposal is to measure the impact of these drugs on energy metabolism in mice at the tissue and cellular levels using quantitative imaging techniques. We will determine metabolic parameters liver, skeletal muscle, and white adipose tissue from 1 year old adult mice that have been untreated or treated for 10 months with CR or one of the three CR mimetics.
|Woojong Lee||BIOPHYSICAL APPRAOCH TO THE LEADING CAUSE OF THE BREAST CANCER: SND1 AND MTDH INTERACTION
Staphylococcal Nuclease homology Domain containing 1 (SND1) is known to be overly expressed in many different types of cancers, including lung, liver, and breast cancers by forming a complex with Metadherin (MTDH). However, the biophysical aspect of the duplex is poorly understood. With the knowledge of the structure of full-length SND1, It is possible to test how SN 1/2 domains affect the degradation of RNAs versus full SND1 structure using the proteins prepared by the standard molecular cloning. Particularly, knowing that SND1 interacts with MTDH, it is also possible to test whether MTDH peptides can affect the activity of SND1 to recognize and cleave double-stranded RNA. Based on previous observations, the 20-bp double-stranded RNAs containing four Watson?Crick base-paired AAUA/UAUU or four wobble-paired IIUI/UIUU can be possible candidates as substrates for RNA degradation by SND1.
|Christina Vaughan||Sequence analysis of Aleutian Disease Virus (ADV) strains in captive North American mink
Aleutian disease virus (ADV) is a member of the parvoviridae family which primarily affects mink, often resulting in death. A few strains have been identified and genotyped, but full genomic analysis of recent circulating strains has not been published in North America. Nine viral genomes were amplified in segments using polymerase chain reactions (PCR) and sequenced using Sanger dideoxy method. Sequences were assembled and aligned using CLC Workbench software and compared to known reference strains of ADV. The deduced amino acid sequences were also analyzed for changes that could affect pathogenicity. Phylogenetic trees were configured for the genomic sequence as well as the four viral proteins in order to identify strain relatedness. Phylogenetic analysis based on nucleotides revealed clustering based on ranch location, with the strains originating in Idaho and Utah clustered together and the Wisconsin strains forming a second cluster. The identification of similarities and differences between the strains can ultimately be used to help develop diagnostic tools to rapidly classify phylogenetic relationships.
|Kevin Miller||Characterization of sox9b expression and function in zebrafish neural development
The transcription factor Sox9 is involved in many developmental regulatory processes, but little is known about its spatial and temporal role in brain development in zebrafish. Sox9 has been shown to induce and maintain mammalian neural stem cells, and is implicated in the switch from neurogenesis to gliogenesis during development. Using a transgenic reporter line, I have characterized the expression pattern of the zebrafish homolog sox9b during neural development. In addition, I have shown that antisense morpholino oligonucleotide knockdown of sox9b perturbs the neurovascular network, glial cell morphology, and neuronal architecture. By using these two approaches, the important functional role of sox9b in zebrafish brain development can be better understood.
|Steven Nemcek||Fibroblasts and Mesenchymal Stromal Cells are Phenotypically Identical
Background: Human mesenchymal stromal/stem cells (MSCs), derived from many different tissues, are characterized by a fibroblast-like morphology, expression of certain cell surface markers, and their ability to differentiate into adipocytes, chondrocytes, and osteoblasts. A number of studies have shown that MSCs share characteristics with fibroblasts.
Methods: We used existing strains of fibroblasts from four different tissue sources and MSCs from two different tissue sources to compare properties that characterize MSCs and fibroblasts.
Results: We found that fibroblasts show similar morphology as MSCs, express the same surface markers as MSCs, and differentiate into adipocytes, chondrocytes, and osteoblasts like MSCs. Also like MSCs, fibroblasts do not express major histocompatibility complex class I (HLA-ABC) but do express class II (HLA-DR) when stimulated with interferon gamma (IFN?) and are capable of suppressing T cell proliferation. Lastly, we found that MSCs deposit extracellular matrices of fibronectin and collagen similar to those deposited by fibroblasts.
Discussion: Based on currently accepted definitions for cultured human MSCs and fibroblasts and protocols used to generate them, MSCs and fibroblasts are indistinguishable. Therefore, the use of fibroblasts may represent an alternative strategy for cellular therapy.
|Hailey Bussan||Is acyl-homoserine lactone a plant cell death signal?
Pectobacterium carotovorum is a gram-negative bacterium that causes soft rot, decay, and wilt on diverse plant species. P. carotovorum symptoms are caused by the plant cell wall degrading enzymes (PCWDE), which are secreted through the type II secretion system (T2SS). It also encodes a hrp type III secretion system (T3SS), multiple harpins, and a single known effector, DspE. Although the P. carotovorum T3SS is not required for expression of PCWDE or the T2SS in culture, strains lacking a functional T3SS or dspEF are impaired in initiating soft rot symptoms in potato and tobacco leaves. When P. carotovorum is infiltrated into leaves, numerous central metabolism and virulence genes are expressed at a significantly higher level in wild type P. carotovorum compared to strains lacking the T3SS sigma factor hrpL operon or dspEF. One of the down-regulated genes, the AHL synthase expI, is required for production of the quorum sensing molecule acyl-homoserine lactone (AHL). AHL is required for up-regulation of the PCWDE in culture and during disease. Co-infiltration of leaves with P. carotovorum wild type or mutant strains with an Escherichia coli strain carrying a plasmid that encodes GFP under the control of an AHL-inducible reporter confirmed that AHL sensing was enhanced when P. carotovorum encoded dspEF and was therefore able to elicit plant cell death. Our data suggest that plant leaf cells take up or modify AHL and that plant cell death elicited by the T3SS allows AHL to accumulate and be sensed by the bacterial cells, which then up-regulate virulence genes, including the PCWDE, and initiate symptom development.
|Owen Bowie||Optic nerve axon counts in a cat model of glaucoma
Bowie, Owen3; Teixeira, Leandro B.1; Nork, T.M.3,4; Dubielzig, Richard R.1,4; McLellan, Gillian J.3,4
1Pathobiological Science, UW-Madison School of Veterinary Medicine, Madison, WI; 2Comparative Ophthalmic Research Laboratories, Madison, WI; 3Ophthalmology and Visual Sciences, UW-Madison, Madison, WI; 4University of Wisconsin Eye Research Institute, Madison, WI
Purpose: To quantify axons loss in the optic nerves of glaucomatous and normal cats throughout different life stages.
Methods: Axons were counted in the optic nerves of cats with mild to severe glaucoma (n= 34) and normal cats (n=30). Optic nerves were selected from both a short-term cohort of young glaucomatous (n=10) and normal (n=8) cats euthanized at 10-12 weeks of age; and from a long-term cohort of cats euthanized either at 6 months, 12 months, 18months or 24 months which consisted of (n=23) glaucomatous and (n=23) normal cats. Following perfusion fixation with 4% paraformaldehyde and enucleation, 2mm long samples of optic nerve were dissected 2mm posterior to the globe fixed in glutaraldehyde, osmicated and resin embedded. Semi-thin sections stained with 1% p- phenylenediamine were evaluated by light microscopy. Axons were quantified by a previously validated, semi-automated targeted sampling method using commercially available image analysis software (cellSens Dimension®, Olympus) and optic nerve cross-sectional area measured using the same image analysis software. Values for normal and PCG cats were compared by student t-test with p=0.05 considered significant.
Results: The mean number of axons in the optic nerves of glaucomatous adult cats (95% CI=38,943- 57,641) was significantly lower than in normal cats (65,150-78,873; p=0.0006) . A significant reduction in optic nerve cross-sectional area was also evident in affected cats compared to normal cats (p=0.0002).
Conclusions: Moderate to severe axonal loss consistent with glaucomatous optic neuropathy was clearly demonstrable in cats with PCG. Our findings support the use of this novel feline model in glaucoma research.
|Kayla McKaveney||Activity of yeast chaperones Ssb and Zuo1 regulates viability and population growth
Molecular chaperones are ubiquitous among prokaryotes and eukaryotes and play a central role in protein homeostasis. Recent evidence demonstrates that the function of yeast chaperone protein partners Zuo1 and Ssb extends to growth regulation. Deletion strains continue growing to high cell densities in low nutrient environments and have longer chronological life spans than wild-type yeast. However, it remains unclear whether these phenotypes are a result of Zuo1 and Ssb-mediated growth arrest or from programmed cell death. I will investigate which of these cellular processes are influenced by Zuo1 and Ssb using Zuo1 mutant H128R, which exhibits less severe growth phenotypes than deletion strains. This project investigates whether partial phenotypes are a result of intermediate enzymatic activity, which may lend insight into growth arrest and programmed cell death. These findings in the Zuo1 and Ssb yeast chaperone system may give insight into growth regulation by orthologues in higher eukaryotes.
|Martin Feehan||Effects of climate on reproductive seasonality in the Northern muriqui (Brachyteles hypoxanthus).
The Northern muriqui (Brachyteles hypoxanthus) is a critically endangered primate species endemic to southeastern Brazil. Muriquis exhibit a seasonal reproductive pattern and anecdotal evidence suggests extended breeding periods follow heavy rainy seasons. This study investigates the effects of rainfall and temperature patterns on the temporal distribution of 181 births in a muriqui population to understand how climate change may affect reproduction in this species. El Niño Southern Oscillation (ENSO), a natural cycle caused by interactions between the Pacific Ocean and the atmosphere, is expected to increase in frequency and severity with global climate change. Analysis of 27 years of birth and climate data will provide insights into whether the more extreme seasonality of future ENSOs will result in more extreme reproductive seasonality in the muriquis.
|Sara Matasick||Feather growth bars as indicators of nutritional condition in Steller’s Jays
Ptilochronology is the study of growth rates of feathers using growth bar measurements. Each growth bar, consisting of alternating dark and light bars on feathers, indicates a 24 hour growing period. The number of bars in a feather corresponds with the feather’s growth rate, and therefore they are used as an indicator of the bird’s body condition at the time of feather growth. Since the most commonly used methods of measuring body condition in individual birds are often invasive and require expensive and complex equipment, growth bar analysis offers a better alternative. It is an easy-to-use method that can be implemented in the field, and when compared to lipid storage is shown to be an accurate measure of individual health.
Here, I assessed whether the number and width of growth bars was correlated with lipid stores in Steller’s Jays (Cyanocitta stelleri). I also tested for differences in mean feather growth bar width across age and sex classes. The use of feather growth bar analysis is an important tool for studies in avian ecology as it provides a reliable and non-invasive measure of body condition in birds.
|Jaob Goldfinger||Simulating fixation of novel mutations in the Moran model
Genetic drift is the change in allele frequencies due to the random sampling that occurs during reproduction. In this study, we use the Moran model to investigate the changing allele frequencies of a haploid population. The Moran model consists of a population of N haploid individuals and has the property that whenever one individual dies another reproduces, maintaining the population always at N. We use the Moran model because it can be used for modeling populations with overlapping generations. We are particularly interested in the dynamics of fixation of new mutant alleles introduced to the population. We use the sorting direct method stochastic simulation algorithm as implemented in Evolvix to simulate this population.
|Kayla Martens||Testing the protective effect of food products on the acid tolerance of Salmonella
One of the most significant hurdles foodborne pathogens encounter is the acid barrier of the stomach. If a pathogen can survive the stomach, it has an increased potential of causing an infection within the host. Certain pathogens such as E. coli 157:H7 are considered to be acid tolerant and thus have a low infectious dose. Other pathogens however, like Salmonella, are sensitive to the low pH of the stomach and require a higher infectious dose. Since Salmonella is not as robust as other foodborne pathogens, it is hypothesized that it may be able to survive due to the protective effect of certain food products. To test this hypothesis the in vitro transmission model (IVTM) was developed. The IVTM simulates the stressful environmental and host conditions a foodborne pathogen encounters as it moves from an asymptomatic host to contaminated food product and ultimately to a human host. The IVTM is a weeklong cycle that includes anaerobic growth conditions as well as varying temperatures and an acid shock with the same pH as the human stomach (pH 3). The focus of the study is to test whether specific conditions such as temperature, fat content, nutrient levels, or pH significantly affect the ability of Salmonella to survive the IVTM. Salmonella was chosen to be tested because it is a good model organism and one of the leading causes of foodborne illnesses in the United States. The food products tested include whole and skim milk, egg substitute and tomato juice.
|Cody Calkins||Nutrient Upcycling of Ammonia into Fertilizer
Nitrogen (N) pollution is a significant environmental problem, leading to groundwater contamination and eutrophication of surface waters. Moreover, it also incurs substantial economic costs. In the US alone, 2.34 million metric tons of N pass through wastewater treatment plants where over half this amount is intentionally volatilized, and thereby lost, as N2 and N2O in order to meet water quality standards. This process generates significant costs for the treatment plants. We propose to capture this nitrogen, valued at $768 per ton (USDA, 2012), concentrate it with an electrodialysis cell, and sell it as an agricultural fertilizer, providing an statewide economic benefit of over $32 million to wastewater treatment plants. Initial experiments show that ammonium enriched solutions can be concentrated by 30-50%, easily matching the amount of nitrogen currently volatilized by the municipal wastewater treatment plants. Furthermore, a number of other readily recoverable waste streams exist that can be electrochemically separated to yield aqueous ammonia including manure lagoons, industrial streams, and manure digesters.
|Eric Polich||RNA Binding Protein HuD Regulates Proliferation and Differentiation of Adult Neural Stem Cells
Adult neurogenesis in the adult brain has been shown to exist primarily in the dentate gyrus (DG) of the hippocampus and the subventricular zone (SVZ) of the lateral ventricles. These two distinct pools of neural stem cells (NSCs) generate different subtypes of neurons and respond independently to environmental cues. However, the mechanisms that differentially controls neurogenesis in these two brain regions are still unclear. The RNA binding protein HuD is a regulator of neuronal differentiation and involved in paraneoplastic encephalomyelitis disorders with learning deficits. Here, we found HuD has distinct expression patterns in these two neurogenic regions. HuD is expressed throughout the process of SVZ neurogenesis from NSCs to mature neurons, whereas HuD is only expressed in NSCs and doublecortin-positive immature neurons in the DG. We found that HuD exhibits differential regulatory roles in NSCs derived from these two neurogenic regions. Furthermore, we found HuD may regulate SVZ-NSCs and DG-NSCs differentiation through different molecular mechanisms. Taken together, investigation of the differential regulation in the SVZ and DG NSCs by HuD will not only shed light on a mechanism that governs the different neurogenesis in these two neurogenic zones, but also provide mechanistic insights into paraneoplastic encephalomyelitis.
|Nicole Worswick||Investigation of cross-presentation and dendritic cell targeting via the use of recombinant monoclonal antibodies
The adaptive immune system is essential for the elimination and immunological memory of pathogens that are not eliminated by the innate immune system. A key aspect of the adaptive immune system is the ability for antigen presenting cells (APCs) to recognize, internalize, process, and present antigens to specific cells that will continue coordinating a response. However, the mechanisms behind these processes are under investigation. Currently, it is known that a particular APC, the dendritic cell (DC), can process endogenous and exogenous pathogens, load them onto major histocompatibility complexes I/II (MHC I/II), and present respective antigens to CD8+ and CD4+ T cells respectively. However, cross-presentation, the process in which extracellular antigens are loaded onto MHC I and subsequently presented to CD8+ T cells, is not well understood. There are two proposed pathways: cytosolic and vacuolar. The key difference between these two pathways is the potential dependence of transporter associated with antigen processing protein (TAP) within the cytosolic pathway. With the use of recombinant monoclonal antibodies (rm-Abs) and dendritic cells derived from TAP1 knockout mice, we studied which proposed pathway is utilized in two different DC subclasses by analyzing subsequent CD8+ T cell activation. Concurrently, by targeting various DC receptors with respective rm-Abs, we also studied DC-targeting to determine which DC receptors, once targeted, will result in a larger CD8+ T cell activation. Further characterization of the mechanisms of the immune system and DC-targeting has exciting implications such as the potential for more efficient vaccination methods.
|Paul Rowley||Unexpected Brain MRI Findings in Research Volunteers
Author Block: P.A. Rowley, A. Field, E. Simcock, A. Munoz Del Rio, H. Rowley; Madison, WI/US
Methods and Materials: 6441 consecutive subjects (< 1 to 94 years) were recruited from a single institution, referred from over 100 IRB-approved brain research studies. All scans were uploaded to PACS and interpreted by Neuroradiologists using an on-line structured report. Research technologists and staff were also prospectively asked to document concerns discovered while scanning or processing.
|Kush Patel||Epigenetic regulation of matrix metalloproteinases by folic acid to alleviate spinal cord injury-induced neuropathic pain
A clinical problem that patients endure following spinal cord injury (SCI) is neuropathic pain (NP). We hypothesize that folic acid can alleviate spinal cord injury-induced neuropathic pain (NP) by DNA methylation-mediated suppression of the expression of matrix metalloproteinases (MMP). Inhibiting MMP2 and MMP9 expression significantly decreases neuropathic pain in animals that have undergone contusion spinal cord injury. The goal of this study is to determine if folic acid can regulate the expression of MMP genes. In this study, Sprague-Dawley rats will receive contusions to their spinal cord that mimic a SCI. Rats will then receive no treatment, distilled water, or folic acid. The spinal cord will be harvested and analyzed for MMP levels by western blot and zymography. This study will address the use of folic acid supplements as a way to manage pain from SCI.
|Maggie Sundstrom||Hopkins Verbal Learning Test, Brief Visuospatial Memory Test, and Trails Making Test in Stroke Patients
Deficits in memory, processing speed, and language abilities are frequently reported with increasing age and also with disease. Extensive research has investigated these changes and efforts are on to identify neuroimaging biomarkers that could be significant predictors of cognitive impairment. We hypothesized that acute stroke patients (less than 7 days from stroke) would show decreases in cognitive abilities based off of scores on Hopkins Verbal Learning Test(HVLT) and Brief Visuospatial Memory Test(BVMT),compared to patients with Transient Ischemic Attack (TIA) and healthy normal controls, and show improvements from acute to sub-acute stage (<6 months from stroke). . HVLT tests a subject’s verbal memory and BVMT tests a subject’s visual memory. Stroke patients, less than 7 days from stroke onset (N=50, mean age= 58.1) scored significantly (p<0.05) lower than TIAs (N=22, mean age=63.9) and healthy controls (N=44, mean age=37.8) in total recall and delayed recall categories. There was also a significant difference (p<0.05) between acute stroke (N=25, mean age=60.4) and sub-acute stroke (N=15, mean age=56.4) with sub-acute stroke patients scoring higher. There was no significant difference between TIA and healthy controls. In the Brief Visuospatial Memory Test, stroke patients (N=40, mean age=54.8) scored significantly lower (p<0.05) than healthy controls (N=42, mean age=36.9) in total recall, but higher in learning. Results are discussed in terms of change in cognitive profile following stroke and correlates with brain plasticity changes.
|John Brennan||Linking grasshopper diversity to plant diversity in the Ozark glades
The Ozark ecosystem has remained largely untouched by human influence. As such, the Ozarks make an ideal system to study basic ecological questions—especially with regards to biodiversity, and especially within glades, open areas of grassland surrounded and isolated by woods. The goal of this research was to determine if any correlation existed between grasshopper diversity and plant diversity within these glades. We collected samples of grasshopper communities from fifteen different sites within these glades, which had been previously surveyed for vegetative abundance and species diversity in 2012 and 2013. Combining the information recorded from the grasshopper and invertebrate analysis with the earlier vegetative analysis will allow a view of the interplay between invertebrates and plant species within these glades, information that can be applied to conservation policy in the Ozark glades themselves and elsewhere. We were able to determine a marginally significant trend that positively correlated grasshopper abundance to plant species richness in 12 of the glades studied.
|xxx||ROI Analysis of Rhesus MRIs
|Nicholas Sanchez||Non-enzymatic Approach to Carry out DNA Damage Response
Understanding natural DNA damage responses is essential to study consequent diseases resulting from the inability to repair damaged DNA and to ultimately develop treatments for these diseases. Double strand breaks (DSBs) are a form of DNA damage that are naturally repaired by ubiquitylation and sumoylation of RAP80 from the BRCA1-A complex. Thiol-ene chemistry can be used to mimic the ubiquitylation/sumoylation of RAP80 by creating hybrid ubiquitin/SUMO polymers. It has been shown that a SUMO-ubiquitin-ubiquitin trimer bound to RAP80 with high affinity and resulted in the activation of BRCA1-A (Guzzo et al. 2012). In this study, I will show that thiolene chemistry can be used to synthesize this trimer as well as a trimers of different linkages. Controlled synthesis of these polymers is the next step to understanding the DSB damage response. Thiol-ene chemistry is a novel method to synthesize ubiquitin and SUMO polymers that display features of natural protein linkages.
|Rehan Tariq||Can AHL Acylases of P.syringae Degrade AHLs of Neighboring Microbes?
Two Pseudomonas syringae strains, called Str1 and Str2, constitutively express AHL acylases and have the capacity to degrade AHLs, or acyl homoserine lactones. These signaling molecules are involved with quorum sensing, or the ability of bacterial cells to communicate in a cell density-dependent manner. The purpose of my research is to determine if these AHL acylases can degrade AHLs of neighboring microbes. Bioreporters Escherichia coli JB524 and P. syringae BHSL-BQ9 will be used to detect AHL degradation in overspray assays with wild type strains of E. coli, Agrobacterium tumefacieus, and P. syringae. We expect that the constitutive production of AHL acylases by strains Str1 and Str2 will allow the strains to degrade AHLs of neighboring bacteria.
|Claudia Roen||Mutations of green fluorescent protein (GFP) to produce binding variants with cyan and yellow fluorescence
Green fluorescent protein (GFP) is an inherently fluorescent molecule whose versatility gives rise to a broad spectrum of biological applications including detection of protein trafficking, labeling of virus strains and mapping of neuronal circuits. Previous work in our lab has demonstrated the ability of GFP to accommodate the insertion of the variable binding domains of antibodies to create novel GFAb molecules that can be used to selectively bind antigens as a single-step detection reagent. The barrel structure of GFP houses a chromophore that is responsible for the protein’s fluorescence and to which mutations make possible color variants such as cyan GFP (CFP) and yellow GFP (YFP). The engineering of a cyan GFAb (CFAb) and a yellow GFAb (YFAb) holds the potential to surpass the utility of binding and color GFP mutants alone and may be demonstrated through the application of fluorescence resonance energy transfer (FRET). FRET is a distance-dependent transfer of energy between two fluorophores and has been vital to the better understanding of protein interactions involved in drug therapies and disease. The combination of binding and color mutations to GFP will allow for the real time, intracellular labeling of multiple antigens in different colors simultaneously.
|Jeffrey Lin||Orifice-Drained Concrete Pavement (ODCP)
Flood damages amounted to $8.4 billion worth of damage across cities in the United States in 2011 (NOAA, 2011). Flooding is caused by stormwater runoff from impervious urban surfaces such as concrete pavement. Originating from precipitation or polluting snowmelt that is not absorbed and filtered by the ground, stormwater runoff is an engineering challenge that is becoming more prevalent due to factors such as climate change and urbanization.
Orifice-Drained Concrete Pavement (ODCP) can help us overcome this engineering challenge by evolving concrete sidewalks, streets, and parking lots into advanced stormwater management structures. ODCP provides stormwater pollution, flow control, and unique cold-weather safety features while being built from traditional concrete technology. Without sacrificing the benefits of modern conventional concrete that have made concrete a fundamental engineering material for nearly a hundred years, this invention can help make our cities safer, healthier, and more enjoyable places to live.
The research being disclosed is in regards to ODCP, a water permeable pavement system that drains water through tapered vertical drainage pathways that span the entire depth of the pavement system rather than off of side joints or through interparticle voids. In addition to stormwater management benefits, the concept of tapered drainage pathways adds cold weather safety and durability features to modern concrete pavement. The pathways can be filled with filtration material such as sand or gravel for greater water flow and pollution control. The invention can be produced on-site or in a plant from the same aggregate mixes as those of conventional concrete. Its production is made efficient by the use of a top mold system, which consists of multiple orifice molds, which is inserted during the casting process of the pavement. The pavement system is preferably placed over a subsurface reservoir capable of holding or transporting the water that passes through the pavement.
|Emily Halter-Lindquist||The Transformation of P. tremula x alba by A. rhizogenes in In Vitro and Ex Vitro Conditions
Plants have natural means of transformation through the delivery of foreign DNA by members of Agrobacterium tumafaciens and rhizogenes. The mechanism of this relationship can be put to work in directed transformation by first transforming a plasmid carrying genes of interest into the Agrobacteria before introducing the bacteria to the plants. P. tremula x Alba is inoculated with A. rhizogenes capable of transforming the roots with plasmids carrying fluorescent markers GFP and RFP, for easy identification of transformed tissues. Transformation can occur in in vitro or ex vitro conditions. The roots are screened to look for signs of fluorescence under the microscope to confirm transformation. Once found the transformed root is isolated and re-propagated to produce a fully transformed plant. When a successful procedure is established for P. tremula x alba, the A. rhizogenes will carry a cassette with a known mycorrhization gene to trigger RNA interference, and the transformed cuttings will provide a source of knock-down mutants with which to compare the chemical signaling mechanisms used in the pathway during establishment of mycorrhization.
|Melissa Ptak||A food-based approach to reducing Vitamin A deficiency among women and children ages 6-59 months in southern Ethiopia: a cross-sectional study of nutrition and health indicators
One micronutrient essential for proper growth and development is Vitamin A. Vitamin A plays a critical role in eye health, vision, proper immune system functioning, growth, and development in all human beings. Children and pregnant women are most susceptible to vitamin A deficiency (VAD) because of the higher intake requirements needed during critical growth periods. Globally, VAD affects 33.3% of preschool-age children and 15.3% of pregnant women. The highest prevalence and burden of VAD is in developing regions, where food security is low. Given the multi-faceted impacts of VAD, a food-based approach that emphasizes consumption of Vitamin-A rich foods is encouraged as a strategy to reduce VAD as a means to support sustainable livelihoods. In particular, the use of orange-fleshed sweet potato (OFSP), when introduced along with nutrition education at the community level, is a proven, cost-effective strategy for providing VA at high levels of bioavailability to vulnerable populations. In 2012, the International Potato Center (CIP) partnered with the University of Wisconsin-Madison (UW) and stakeholders from agriculture, nutrition and health in the Southern Nations, Nationalities, and Peoples Region (SNNPR), Ethiopia, to implement a food-based approach to reduce VAD among rural households from the Southern Nations, Nationalities, and Peoples’ Region (SNNPR), Ethiopia. This poster will present cross-sectional analysis of nutrition and health indicators associated with Vitamin A from surveys conducted in 150 households in 5 districts. Of 150 households surveyed, 63% of mothers self-reported knowledge about Vitamin A. Among those who reported knowledge about Vitamin A, 8% identified OFSP as a source of VA, 1% had consumed OFSP in the past 7 days, and 0% reported that they ever prepared OFSP with an animal- or vegetable-based fat. Among those reported knowledge about Vitamin A, 96% knew that it is necessary for good health. Vitamin-A related health issues among these households include night-blindness (32%), measles (32%), and malaria (72%). Further analysis is being conducted to understand the associations between Vitamin A knowledge and behavior and health outcomes in the local context.
|Ryan Raut||Altered functional activation maps in stroke patients due to neurovascular uncoupling
While blood oxygenation level-dependent functional MRI (BOLD fMRI) has proven to be a useful tool for functional brain mapping, its validity can be compromised in the presence of a diminished relationship between neural activity and cerebral blood flow. This phenomenon, known as neurovascular uncoupling, has previously been observed in the aging and various patient populations. For this reason, we hypothesized that stroke patients would show decreased vascular reactivity compared to healthy subjects. We compared the functional activation maps of acute stroke patients (< 7 days from stroke onset) (N = 30, mean age = 60 years) with those of younger ( 50 years) (N = 22, mean age = 59 years) healthy subjects from a breathhold task performed in the MRI scanner. Results indicated that stroke patients showed significantly less vascular reactivity in the right thalamus and right superior frontal gyrus (cluster p < .05) compared to older healthy subjects. These results suggest that neurovascular uncoupling may indeed be present in the stroke population, though further research is needed to better characterize the relationship between neural and vascular activity in this group.
|John Buol||Corn grain yield as influenced by nitrogen and pesticide inputs
Fertilizer and pesticides are integral components of cropping system management in Wisconsin agriculture. Volatile grain prices, shifting climate trends, the development of pesticide resistant crop pests, the loss of agricultural resources, and the expected surge in global population all combine to necessitate a better understanding of the relationship between management inputs and crop yields. We seek to characterize the relationship between two such inputs, nitrogen fertilizer (N) and varying degrees of pesticide input levels (PL), and to determine how this relationship affects corn grain yield. Initial field experiments were conducted at the University of Wisconsin Arlington Research Station in 2012 and 2013 and analyzed the relationships between two levels of N (207 kg N ha-1 or 151 kg N ha-1) and five levels of pesticide input (PL-1 through PL-5). Each treatment included a postemergence (POST) glyphosate application at V6 corn growth stage at the rate of 0.87 kg a.e. ha-1 plus 2.8 kg ha-1 ammonium sulfate. PL-2 through PL-5 then received additional pesticide control inputs in order of increasing input rigor. Analyses of crop yield data as influenced by the relationship between N rate and PL inputs will be used to develop further studies and to contribute to a growing understanding and manipulation of management input influence on crop yields.
|Jennifer Schlobohm||Daphnia Length Distribution in Response to the Invasive Spiny Water Flea
Bythotrephes longimanus is an invasive zooplankton species that preys upon native zooplankton, such as Daphnia galeata mendotae and Daphnia pulicaria. Bythotrephes is a size selective predator and has been documented to influence the length distribution of Daphnia species, causing it to become bimodal, comprised of only very small (2.5 mm) Daphnia. Lake Mendota and Lake Monona are eutrophic lakes that have been manipulated to induce a trophic cascade to increase water clarity, creating a food web that favors D. pulicaria grazing. Considering the value of water clarity in each lake, it is important to address the effect of a bimodal length distribution on Daphnia species’ grazing capacity since they are size selective algal grazers whose size distribution influences water clarity. The first step to addressing this issue is to determine whether Bythotrephes predation has selected for a bimodal length distribution in D. g. mendotae and D. pulicaria. In order to detect potentially bimodal length distributions the multimodality of Daphnia length distribution during growing season in the presence of Bythotrephes was compared that of the distribution without Bythotrephes. We found the length distribution of Daphnia to be more bimodal in the presence of Bythotrephes, which may likely impact water clarity.