91 lines
9.3 KiB
HTML
91 lines
9.3 KiB
HTML
---
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title: Academic Achievements
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imageUrl: ../img/library.jpg
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blurImageUrl: ../img/library_blur.jpg
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motto: Academic Publications and Presentations
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---
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<dl>
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<dt>Metagenomic analysis of rumen populations in week-old calves as
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altered by maternal late gestational nutrition and mode of delivery</dt>
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<dd>
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T. A. Christensen II, K.J. Austin, K. M. Cammack, and H. C. Cunningham-Hollinger
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<br />
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Westion Section American Society of Animal Science Annual Meeting ● Boise, ID ● June 12, 2019
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<br />
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1<sup>st</sup> Place Undergraduate Poster Competition
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<br />
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<a data-toggle="collapse" data-target="#metagenomics-abstract" role="button">Abstract <span class="caret"></span></a>
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<div class="collapse" id="metagenomics-abstract">
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<p class="font-serif">Early colonization of the rumen microbiome is critical to host health and long term performance. Factors that influence early colonization include maternal factors such as gestational nutrition and mode of delivery. Therefore, we hypothesized that late gestational nutrition and mode of delivery would influence the calf rumen microbiome. Our objectives were to determine if nutrient restriction during late gestation alters the calf rumen microbiome and determine if ruminal microbiome composition differs in calves born vaginally versus caesarean. Late gestating Angus cows were randomly allocated to one of three treatment groups: control (<b>CON</b>; n = 6), caesarean section (<b>CS</b>; n = 4), and nutrient restricted (<b>NR</b>; n = 5), where CON were fed DDGS and hay to meet NRC requirements and calved naturally; CS were fed similarly to CON and calves were born via caesarean section; and NR were fed at a level to reduce BCS by 1.5-2.0 points over the last trimester compared to CON and calved naturally. Rumen fluid was collected via oral lavage prior to partition from cows and at d 7 from calves. Microbial DNA was isolated from the rumen fluid and metagenomic shotgun sequencing was performed using the Illumina HiSeq 2500 platform. Sequence data were analyzed using Metaxa2 for taxonomic assignment followed by QIIME1 and QIIME2 to determine differential abundance and alpha- and beta-diversity differences. There were no significant differences in alpha-diversity as measured by shannon index across treatment groups for cows (<em>P</em> = 0.239), but there were significant differences for calves (<em>P</em> = 0.015). Similarly, there were no significant differences in beta-diversity as measured by the bray-curtis dissimilarity matrix for cows (<em>P</em> = 0.059), but there were significant differences for calves (<em>P</em> = 0.007). Alpha-diversity differed (<em>P</em> < 0.001) between cows and calves, with cows having increased species richness compared to calves. Beta-diversity also differed (<em>P</em> = 0.001) between cows and calves. At total of 410 taxa were differentially abundant (<em>P</em> < 0.01) between cows and calves. These results suggest that the mature rumen microbiome of cows is able to withstand changes in feed intake, however the calf microbiome is susceptible to alteration by maternal factors. These data also suggest that there may be opportunities to develop management strategies during late gestation that influence calf health and performance long-term.</p>
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<p><b>Key words</b>: gestation, metagenomics, microbiome, rumen</p>
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</div>
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</dd>
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<hr />
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<dt>The ChemE Car that Cud: Entry and Documentation Packet to AIChE ChemE Car Contest</dt>
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<dd>
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Thomas Christensen II, Andrew Halverson, Kennedee True, Seth Messick, Amanda Christensen, Caleb Richmond, Alexander Brown, & Jake Maksin with Dr. David Bagley
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<br />
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Rocky Mountain Regional AIChE Student Conference ● Golden, CO ● April 6, 2019
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<br />
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2<sup>nd</sup> Place Poster Competition ● 7<sup>th</sup> Place Performance Competition
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<br />
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<a href="https://hdl.handle.net/20.500.11919/3817">Publication Link</a>
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<a data-toggle="collapse" data-target="#cheme-car" role="button">Abstract <span class="caret"></span></a>
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<div class="collapse" id="cheme-car">
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<p class="font-serif">The ChemE Car That Cud showcases Wyoming’s dominant industries of agriculture and mining by utilizing rumen fluid from a cannulated beef cow to generate hydrogen to be used in a hydrogen fuel cell and radioactive cesium, a byproduct of uranium that is often obtained from Wyoming’s mines, to time the car’s stop. The concentration of cesium-137 source is measured using the radioactive decay of cesium shielded by aluminum. The painted aluminum chassis was obtained from a previous team at UW, and modified using plastic k’nex toys to adapt to the current power source and stopping mechanism.</p>
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</div>
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</dd>
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<hr />
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<dt>Measuring Diffusion of Trichlorethylene Breakdown Products in Polyvinylalginate</dt>
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<dd>
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Thomas A. Christensen II, Samuel R. Wolfe, Jonathan Counts, Mark F. Roll, Kristopher V. Waynant, James G. Moberly
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<br />
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AIChE Annual Meeting ● Pittsburgh, PA ● October 29, 2018
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<br />
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3<sup>rd</sup> Place Environmental III Division Undergraduate Poster Competition
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<br />
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<a href="https://aiche.confex.com/aiche/2018/meetingapp.cgi/Paper/545790">Conference Schedule Listing</a>
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<a data-toggle="collapse" data-target="#pva-aiche" role="button">Abstract <span class="caret"></span></a>
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<div class="collapse" id="pva-aiche">
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<p class="font-serif">Trichloroethylene (TCE), a toxic and carcinogenic contaminant, presents unique challenges for cleanup because of its water solubility, density, and volatility. Bioremediation of TCE is a promising cleanup method; however, metabolism of TCE results in acid generation that inhibits remediating microorganisms. Calcium alginate(CA)-polyvinylalcohol (PVA) hydrogels show promise for protecting remediating microbes, however diffusion of TCE or its byproducts through these polymers is unknown. To measure the effective diffusion coefficient of TCE and byproducts through hydrogel membranes, we used a modified diaphragm cell. Measured effective diffusion coefficient of each species was (cm<sup>2</sup>/s ×10<sup>6</sup>): 14.0 ± 1.91 for H+ ions, 12.4 ± 1.64 for TCE, 7.83 ± 0.54 for cis-1,2-dichloroethylene (DCE), and 4.68 ± 4.14 for vinyl chloride. These results aid in engineering biobeads and suggest that CA-PVA hydrogel blends are effective in slowing diffusion of protons, buffering acids produced by trichloroethylene metabolism, and remains suitable for encapsulation of microorganisms involved in bioremediation.</p>
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</div>
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</dd>
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<hr />
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<dt>How to build a cow-cud fuel cell</dt>
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<dd>
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Thomas A. Christensen II
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<br />
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Idaho INBRE Summer Research Conference ● Moscow, ID ● August 1, 2018
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<br />
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3<sup>rd</sup> Place Fast-Pitch Science Presentation Contest
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<br />
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<a href="https://web.archive.org/web/20190928024416/https://inbre.uidaho.edu/research/research-conference/">Awards Listing</a>
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</dd>
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<hr />
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<dt>Measuring diffusion of protons in polyvinylalginate</dt>
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<dd>
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Thomas A. Christensen II, Jonathan Counts, James G. Moberly
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<br />
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Idaho INBRE Summer Research Conference ● Moscow, ID ● July 31, 2018
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<br />
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Undergraduate Poster Competition
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<br />
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<a href="https://eventmobi.com/idahoinbre2018/people/c861bd6f-f4a7-4d67-a59a-199e34515776/387725dc-c893-44b6-b611-0abdf5fbcf6e">Conference Schedule Listing</a>
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<a data-toggle="collapse" data-target="#pva-inbre" role="button">Abstract <span class="caret"></span></a>
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<div class="collapse" id="pva-inbre">
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<p class="font-serif">Trichloroethylene (TCE) is a toxic and carcinogenic contaminant that presents unique challenges for cleanup because of its density and volatility. Use of microorganisms may be a promising remediation method, however metabolism of TCE results in acid buildup, which consequently impedes the ability of microorganisms to perform this remediation. Polyvinylalginate (PVA) shows promise as a useful shield for microorganisms carrying out bioremediation of TCE by surrounding them in a protective biofilm-like layer, however, key information is missing which relates diffusion of TCE or its metabolic products through PVA. To measure the effective diffusion coefficient of H+ ions through a PVA membrane cross-linked with boric acid and calcium ions, we used a modified diaphragm cell. We found the effective diffusion coefficient to be 1.40 × 10<sup>-5</sup> ± 1.91 × 10<sup>-6</sup> cm<sup>2</sup>/s, a nearly seven-fold decrease in diffusivity compared to protons in water, with an unexpected significant but as of yet unquantified adsorption capacity. These results suggest that polyvinylalginate is effective in slowing diffusion of protons and buffering these acids produced by trichloroethylene metabolism, and remains suitable for encapsulation of microorganisms involved in bioremediation.</p>
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</div>
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</dd>
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</dl>
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