NDSU Theses & Dissertations

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Research performed to achieve a formal degree from NDSU. Includes theses, dissertations, master's papers, and videos. The Libraries are currently undertaking a scanning project to include all bound student theses, dissertations, and masters papers.

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Aging and Early Life Stress: Telomerase Dynamics and The Consequences for Telomeres in a Wild Bird
(North Dakota State University, 2020) Vangorder-Braid, Jennifer Teresa
Aging is an underlying risk factor for many major diseases including cancer, cardiovascular disease, and neurodegeneration. Yet we still do not know the full extent of how our bodies age and what determines our lifespan. One mechanism that may play an important role are telomeres, which are protective caps at the end of chromosomes. Telomeres are directly linked to longevity and can be lengthened by the enzyme telomerase. Early life telomere length is critical for lifespan, but we do not know how telomerase performs during this period. Whether variation in telomerase levels can influence telomere length and loss during development with consequences to longevity is still unknown. This thesis focuses on the role of telomerase during post-natal development and its response to stressors and activators with effects on telomeres. Taken together this research enhances our understanding of how telomerase acts and influences telomere during post-natal development.
Alignment of Genetic Variation, Plasticity, and Selection, and the Effects of Cost of Plasticity
(North Dakota State University, 2021) Berdal, Monica Anderson
Phenotypic expression depends on both the underlying genetics and the environment the phenotype is expressed in, i.e., plasticity. Adaptive theory predicts that selection should align with the dimensions of most genetic variation and plasticity because this will increase the evolutionary rate of a population, meaning that a population would reach its fitness optimum faster than if they were misaligned. Alignment with selection is only predicted if there is directional selection, and not under stabilizing selection. In addition, only adaptive plasticity is predicted to align with both selection and genetic variation, with the proportion of the plastic variation consisting of adaptive plasticity determining how well aligned plasticity should be. In the first chapter of this dissertation, I outline the evolutionary consequences of the relationship between selection, genetic variation, and plasticity, as well as what the predictions are for their alignments and how to estimate them. In my second chapter I empirically test the alignment between selection, among- and within-individual variation (used as proxies for genetic variation and plasticity respectively) for three behaviors in a wild population of deer mice (Peromyscus maniculatus). I found that selection, among- and within-individual variation were all misaligned, and that there was very little variation in all three behaviors. This could indicate that the behaviors have already reached their fitness optimum due to previous selection pressure. Consequently, this population might not be able to adapt to environmental change. In my last chapter I investigate the cost of plasticity in response to a predatory cue on reproductive outputs in isogenic lines of the banded cricket (Gryllodes sigillatus). Plasticity is assumed to have associated costs which would affect its alignment with selection and genetic variation. I found no evidence for cost of plasticity in G. sigillatus, and in addition there was no genetic variation in plasticity among the lines. Again, previous selection might drive the population’s mean plasticity to its fitness optimum, reducing the variation and the costs of plasticity, making it harder to detect.
Alluvial Fans in the McMurdo Dry Valleys: A Proxy for Melting Along Terrestrial Margins of the East Antarctic Ice Sheet
(North Dakota State University, 2013) Zamora, Felix
Surface melting along Antarctic ice sheet margins is the most poorly understood input in models of future sea level rise. Alluvial fans in the McMurdo Dry Valleys originate from meltwater produced from high-elevation glaciers and snowbanks along these margins but many show no evidence for recent melting. These fans could serve as a record of past melting along terrestrial ice sheet margins, which would help quantify inputs to sea-level rise.To describe how melting has taken place in the past, five representative fans were examined. Fans are composed of thin, planar-bedded gravelly sands deposited by sheetflooding. Geospatial analsysis suggests the distance of the meltwater source from the Ross Sea is the predominant control on fan activity, and that aggradation results when regional climatic gradients shift inland. Geomorphic observations suggest centuries to millennia pass between periods of aggradation. OSL dating indicates that fans are no older than Holocene in age.
Ammonia Oxidizing Archaea in Engineered Water and Wastewater Systems: Presence, Activity and Relationship to Heavy Metal Inhibition, and Disinfectants
(North Dakota State University, 2017) Roy, Dhritikshama
Ammonia oxidizing archaea (AOA) have been found as a key player in ammonia oxidation. Over the past decade, AOA have been shown in some cases to outnumber ammonia oxidizing bacteria (AOB) in marine, terrestrial and aquatic environments, and to participate in nitrification. In this dissertation research, AOA along with AOB were examined for their presence and activities in wastewater treatment plants (WWTPs), and water treatment plants (WTPs) employing different disinfectants and their distribution systems (DSs). Firstly, this research investigated the abundance and seasonal variation of AOA and AOB by quantitative polymerase chain reaction targeting the ammonia monooxygenase subunit A gene (amoA) in the biofilm from trickling filters (TFs) and a moving bed bioreactor (MBBR) employed separately at two WWTPs. AOA and AOB dominated nitrifying cultures from the same WWTPs were selected using specific inhibitors, and investigated for nitrification activity. Secondly, this research examined copper inhibition of nitrification by attached and suspended growth ammonia-oxidizing cultures containing different fractions of AOA. The third and final research part investigated AOA and AOB abundance and nitrification activity in different treatment steps of WTPs practicing chloramination and chlorination and distal and proximal zones of their DSs. A laboratory experiment simulating DS conditions with chorine and chloramine was conducted to understand the effects of disinfectant concentration and type, and water temperature on AOA and AOB populations and activity. AOA were dominant in the nitrifying TF (NTF) and MBBR, while AOB dominated in the biochemical oxygen demand TF. AOA and AOB were more abundant during warm months. In-situ nitrification activity showed the oxidation of ammonia to nitrite decreased when AOA populations from the NTF and MBBR were inhibited, demonstrating that AOA contributes to nitrification. Nitrification by the cultures heavily dominated by AOA were less inhibited by copper than the cultures with less AOA dominance. In WTP systems studied, more AOA were observed in chloraminated DS compared to chlorinated DSs. More AOA and AOB were detected in the distal zones than the proximal zones of DSs suggesting that AOA and AOB grew in the distribution systems. AOA had longer inactivation time under cold water temperature compared to AOB.
Antipredator Behavior and Morphology in Isolated Cyprinodont Fishes
(North Dakota State University, 2018) Snider, Madison R.
For desert fishes in the American Southwest, predation by invasive species has triggered massive population declines for decades, leaving researchers speculating on the underlying cause. It has been shown that Post-Pleistocene isolation of desert fishes in small habitats with limited predation pressure has led to loss of antipredator traits. Determining the status of antipredator behavioral and morphological traits could identify the most vulnerable desert fishes. In aquatic ecosystems, detection and response to chemical alarm cues derived from epithelial tissue increases the probability of predation survival. In chapter two, I evaluate alarm cue responses of two desert cyprinodontids: endangered Pahrump poolfish and Amargosa pupfish. In chapter three, I assess the prevalence and densities of epithelial club cells, the source of chemical alarm cues, for several desert fishes: Pahrump poolfish, Amargosa pupfish, White Sands pupfish, White River Springfish, and Hot Creek Valley tui chub.
The Applicability of Physiology for Conservation and Management Purposes: A Case-Study Using the Breeding Season of the Red-winged Blackbird (Agelaius Phoeniceus)
(North Dakota State University, 2017) Mahoney, Jessica
Physiology has the potential to play a unique and important role in conservation and management practices by helping identify the mechanistic responses of populations to environmental changes, and providing physiological tools and knowledge that can be applied to help solve conservation and environmental problems. It has previously been unclear, however, if the increase of physiology in conservation and management literature has translated into the application of physiological tools and knowledge into conservation and management plans. There were two purposes of this disquisition: 1) analyze how physiological tools have been integrated into applied conservation by reviewing USFWS endangered species recovery plans, and provide suggestions to help conservation scientists and physiologists work synergistically to solve conservation and management problems, and; 2) provide an example of how studying the physiology of a species can provide useful information for making management decisions, using the study of stress physiology in the red-winged blackbird (Agelaius phoeniceus) during their breeding season as our case study. Our results suggest that physiology is being underutilized in USFWS endangered species recovery plans. We hypothesize this absence of physiological tools and knowledge in conservation planning is primarily due to a deficit of physiological knowledge passing between physiologists and the cohort of federal agency recovery plan writers. We suggest the need for increased training of federal agency employees, the inclusion of authors with academic affiliations, increased integration of physiology and conservation research, and enhanced communication between all concerned parties. To illustrate how physiology can be useful, we exposed female red-winged blackbirds to predator and nest parasitism effigies, thus causing additional stress, during the breeding season. We were able to examine how females respond behaviorally and physiologically to stress, and how these responses alter their reproductive decisions. We found that females are responding both behaviorally and physiologically to the increased threat of predation and nest parasitism. There is potential to exploit these responses to manage the species, such as causing females to forgo breeding. We also determined that an individual’s stress physiology can be changed when held in captivity. We suggest using caution when trying to extrapolate captive data to wild populations.
Assessment of Blackbird Damage to Sunflower and Corn Fields in the Prairie Pothole Region of North Dakota
(North Dakota State University, 2011) Klosterman, Megan Elise
North Dakota is the top sunflower producing state in the United States, annually harvesting about 405,000 ha (1 million acres). Up to 63% of this crop is grown in central North Dakota in an area known as the Prairie Pothole Region (PPR). Since the early 2000s, com also has become a major crop in the PPR due to the development of hybrids for northern crop areas and increases in com prices. Blackbirds (Icteridae) can cause significant damage to both ripening com and sunflower. It has been three decades since a comprehensive sunflower damage survey was conducted in the PPR. I assessed blackbird damage to ripening sunflower and com in 120 randomly-selected plots during three growing seasons, 2008-2010. Damage was analyzed across four strata (Northeast Drift Plains, Northwest Drift Plains, Southern Drift Plains and Missouri Coteau) within the PPR. Landcover was analyzed to determine possible variables (pasture, com, sunflower, open water, wetland, small grains, developed, wooded, beans and other) related to blackbird damage. Stepwise logistic regressions were performed along with AIC model selection to determine significant (p<0.1) independent variables related to sunflower and com damage. Average damage to sunflower (2.14%) was higher than damage to com (0.33%), with sunflower in the Southern Drift Plains having the greatest levels of damage (11.11 %). Beans and wetland showed the greatest significance in relation to sunflower damage (p=<0.001, p=0.035), according to the selected AIC model. The most significant landcover variables surrounding damaged corn fields was open water (p=0.022), showing an increase in damage, and pasture (p=0.056), showing a decrease in damage. The results of this study provide data to help producers make informed decisions about crop selection and location.
Attenuation of Nitrate from Simulated Agricultural Wastewater Using an Immobilized Anaerobic Biofilm
(North Dakota State University, 2012) Anar, Mohammad Jahidul
A number of methods are currently in use for attenuating nitrates from wastewater with varying degrees of efficiency. Bioremediation using bacteria may be an efficient and cost effective method. In an anaerobic bioremediation system, nitrate can replace carbon dioxide as an electron acceptor and aids in nitrate attenuation by assimilatory reduction. The purpose of this study was to investigate nitrate attenuation in a hyperfiltration system using a pure culture of strictly anaerobic, facultative Methanobrevibacter ruminantium bacteria. Filtration experiments were conducted using amalgamated Na- montmorillonite clay-glass beads compacted at 500 psi differential hydraulic pressure with or without a biofilm. A simulated agricultural wastewater of 3.105×10-4 moles/L of NO3- was bioremediated. The use of bacteria in attenuating nitrates offers promising results on a bench-scale.
Biogeochemistry of Wet Ecosystems from Root Zone to Landscape
(North Dakota State University, 2012) Kissoon, La Toya Tricia
The biogeochemistry of wetland ecosystems varies, causing them to act as sources, sinks, filters or transformers of nutrients and pollutants. Wetland plants play important roles in the cycling of elements in wet ecosystems. The structural and physiological adaptations that allow these plants to colonize wetland habitats as emergent or submerged species contribute to biogeochemical processes in wetland substrates. Rhizosphere (root zone) oxidation, iron and manganese oxide precipitation, acidification of the rhizosphere, root exudation, and microbial activity influence the mobility of elements in wetland substrates. Both emergent and submerged wetland plants can alter conditions in the rhizosphere that influence the mobility of elements. These plants are also capable of removing elements such as Cd, Cu, Fe, Mn, N, P and Zn from solution and accumulating them in their tissues. Root zone studies were carried out in the greenhouse using the wetland plants Typha angustifolia (cattail) and Rumex crispus (curly dock) and in the field using Triglochin maritima (seaside arrowgrass) to determine differences in element concentrations in the root and bulk zone under different soil moisture conditions. Studies involving shallow lakes of Minnesota were carried out to determine relationships among (1) landscape variables (e.g. lake watershed size, percent agriculture, percent woodland), water and sediment characteristics (turbidity, chlorophyll-a, organic content, particle size), (3) element concentrations in waters and sediments, and (3) plant abundance and community composition. The studies reported here showed that different factors influenced the distribution of multiple elements in the root zone of emergent wetland plants and in waters and sediments of shallow lakes. First, the root zone studies indicated that pH, redox and moisture content of wetland soils influenced the distribution of elements in the rhizosphere and subsequent uptake of these elements by wetland plants. Second, the shallow lake study showed that land cover uses (agriculture and woodland), lake watershed size, and sediment physical characteristics (organic content and particle size) influenced the distribution of elements in waters and sediments of shallow lakes. Concentrations of these elements, land cover uses, open water area, turbidity, chlorophyll-a concentrations and sediment physical characteristics influenced abundance and distribution of submerged and floating plants.
Body Shape Divergence Among Wild and Experimental Populations of White Sands Pupfish (Cyprinodon Tularosa)
(North Dakota State University, 2011) Kowalski, Brandon Michael
Reports of contemporary evolution have become ubiquitous, but replicated studies of phenotypic divergence for wild populations are exceptionally rare. In 2001, a series of experimental populations were established to replicate a historic translocation event that led to a case of contemporary body shape evolution in the White Sands pupfish. Using landmark-based geometric morphometric techniques I examined phenotypic variation for seven of these populations, and two wild populations over a 5 year period (5-10 generations) in the field. Significant body shape divergence was observed, but divergence patterns were not parallel, suggesting that the ponds were ecologically dissimilar. Considerable body shape variation found among populations suggests that the observed divergence maybe governed by temporal environmental variance. In this study, body shape variation was correlated with population density. These data suggest that habitat intrinsic factors or unmeasured habitat features may have strong affects on body shape, warranting continuous monitoring of recently translocated fishes.
Cell Entrapment for Mitigating Fouling in Membrane Bioreactors Treating Domestic Wastewater
(North Dakota State University, 2018) Juntawang, Chaipon
Membrane bioreactors (MBRs) have been a process of choice for wastewater treatment and reuse because of several advantages over conventional process (activated sludge) including superior quality effluent, less biomass yields and more compact design. However, membrane fouling is a major drawback that hampers widespread and full-scale applications of MBRs. Cell entrapment is a relatively new wastewater treatment process. It involves cells artificially entrapped in a porous polymer matrix. In this dissertation research, three versions of entrapped cells-based MBR processes, aerobic MBR, anaerobic MBR and anaerobic forward osmosis (FO) MBR, were developed by using polyvinyl alcohol as a cell entrapment matrix. Their domestic wastewater treatment performances and fouling characteristics were tested and compared with their suspended cells-based MBR counterparts. For aerobic and anaerobic MBRs, entrapped cells-based processes provided similar organic removal but experienced delayed fouling compared to suspended cells-based processes. The entrapment diminished bound extracellular polymeric substances (bEPS) and soluble microbial products (SMP), which are a main culprit of irreversible fouling through pore blocking. Entrapped cells-based aerobic and anaerobic processes had 5 and 8 times lower pore blocking resistance than corresponding suspended cells-based processes. For anaerobic FOMBR, the entrapment protected cells from reverse salt flux leading to slightly higher organic removal. Lower bEPS and SMP in entrapped cells-based FOMBR led to higher permeate flux compared to suspended cells-based FOMBR. The delayed membrane fouling in entrapped cells-based MBRs means lower costs associated with membrane cleaning processes and longer membrane lifespan. Another contribution of this study is novel knowledge on fouling conditions and mitigation for FOMBR, an emerging wastewater treatment process.
Characterization of Road Dust in Western North Dakota
(North Dakota State University, 2015) Ljepoja, Danijela
Samples were collected during summer 2014, at three locations: along 15th St. SW near agricultural test plots, along an access road leading to a newly built oil drilling pad, and adjacent to the pad. MiniVol™ TAS Samplers (Air metrics, Springfield, OR) were used for sampling. Total Suspended Particles (TSP), and particulates less than 10 or 5 microns (PM10 and PM2.5, respectively) were collected using quartz fiber filters. Samples were collected both pre and post access road and pad construction. The mass concentration of TSP at 15th St. ranged from 365 - 911 µg/m3 (mean 507 µg/m3). Concentrations at the access road ranged from 8 – 68 µg/m3 and near the pad from 9 – 42 µg/m3. SEM/EDS analyses show most particulates are silicate or carbonate mineral fragments or biogenetic particles. The most common particle size is between 2.5µm and 10µm. The main sources of airborne particulate matter observed were from road dust re-suspension, and biological sources.
Characterization of Variation in Growth Performance in Inbred Strains of Zebrafish (Danio Rerio)
(North Dakota State University, 2012) Meyer, Ben Michael
Although zebrafish have been a widely utilized model organism for several decades, there is little information available on physiological variation underlying genetic variation among the commonly used inbred strains. This study evaluated growth performance in response to fasting in six zebrafish strains [AB, TU, TL, SJA, WIK, and petstore (PET) zebrafish]. Fasting resulted in a decrease in whole blood glucose levels in PET, TL, and TU strains and did not affect glucose levels in AB, SJA, and WIK strains. Similarly, fasting had no effect on myostatin mRNA levels in AB, PET, TU, and WIK strains, but decreased myostatin-1 and -2 mRNA levels in SJA zebrafish. Fasting increased myostatin-2 mRNA levels in TL zebrafish. These data demonstrate that growth performance variation is present between commonly used zebrafish strains and can help future research endeavors by highlighting the attributes of each strain so that the most fitting strain may be utilized.
Characterizing the Immune Response of the Alfalfa Leafcutting Bee throughout Pupal Development
(North Dakota State University, 2015) Cummings, Sara Elizabeth
Megachile rotundata is a solitary cavity nesting bee that is the primary commercial pollinator of alfalfa in North America. During prepupal to adult development, they may be exposed to fungal, parasitic, and bacterial pathogens. However, little is known about their immune function throughout pupation. We characterized functional immunity of M. rotundata across development stages. We injected prepupal, pupal, and adult bees with live E. coli and compared mortality across groups. We also developed an assay to measure antimicrobial peptide (AMP) activity in hemolymph for the same age groups. Both pupal and prepupal bees are sensitive to injected E. coli, resulting in high mortality, while adult bees survived longer after infection. Pupal bees had significantly less AMP activity compared to prepupae and adults. Understanding immunity of M. rotundata will provide context for improving commercial rearing practices, where measuring AMP activity can now serve as a biological marker of bee quality.
Chemical Repellents for Reducing Blackbird Damage on Mature Sunflowers: The Importance of Plant Structure and Avian Behavior in Field Applications
(North Dakota State University, 2019) Kaiser, Brandon Amberg
Across North America, blackbirds (Icteridae) depredate high-energy crops, such as sunflower (Helianthus annuus), placing an economic burden on producers. Chemically-defended crops, in the form of human-applied repellents, may induce birds to forage elsewhere if a learned aversion can be established. However, repellent deployment must be feasible for producers at the scale of commercial agriculture. Thus, my main objective was to evaluate the efficacy of anthraquinone-based repellents applied to ripening sunflower for reducing blackbird damage. I conducted concentration response (no-choice) and preference tests (two-choice) to evaluate repellent efficacy on captive blackbirds using application strategies practical for agricultural producers. I evaluated field application strategies to assess the potential for broad-scale application using new drop-nozzle technology. Additionally, I describe behavior of captive blackbirds as they interact with ripening sunflower to further inform repellent application. Our results support the conclusion that application of anthraquinone-based repellents is not currently a feasible option for ripening sunflower.
Chironomids Then and Now: Climate Change Effects on a Tundra Food Web in the Alaskan Arctic
(North Dakota State University, 2019) Lackmann, Alec Ray
Although climate change is a global phenomenon, the Arctic is warming faster than any other region on earth. These climatic changes have driven rapid regional changes over the past half-century in both the physical landscape and the ecosystems therein. One such ecological interaction is between migratory shorebird survival and local insect emergence. Annually, tens of millions of migratory shorebirds travel to the Arctic to rear their young in the relative absence of predators, but in a relative abundance of food (insects). Over evolutionary time, these trophic levels have coupled: shorebird chicks tend to hatch during the period of highest terrestrial insect availability. However, climate change is currently uncoupling this food-web synchrony, creating potential for trophic mismatch. In the High Arctic near Utqiaġvik (formerly Barrow), Alaska, trophic mismatch between nesting shorebirds and their insect food base is already detectable. In this ecosystem, flies in the Family Chironomidae (non-biting midges) dominate the prey trophic level in the avian food web. We have found that the pre-emergence development of one particular midge, Trichotanypus alaskensis, defies conventional wisdom of the Family, as this species molts to an additional fifth larval instar prior to pupation and emergence (all other chironomids are known to have four larval instars). We discovered an Utqiaġvik midge that reproduces asexually, a species that was not documented in the 1970s. Utilizing controlled temperature rearings of Utqiaġvik midge larvae, we discovered that as temperatures rise, emerging chironomid adults are generally smaller in size. We have found that chironomid pre-emergence developmental rates follow a positive exponential relationship as temperatures increase, can vary by taxon, yet are consistent across field and lab settings for a given taxon. At Utqiaġvik in the 2010s, chironomid emergence occurs 8-12 days earlier than it did in the 1970s. These findings shape our understanding of trophic mismatch in this arctic food web.
The Conservation of Variation in Gryllodes sigillatus and Closely Related Cricket Species
(North Dakota State University, 2020) Dalos, Jeremy David
The ability to adjust behaviors to a particular environment has been well documented across taxa. Our understanding of behavioral plasticity is largely based on experiments in which individuals have a single exposure to an environment. Observed behavioral changes are then traditionally measured in small windows of responsiveness in a single population or species. In this project I investigated the effects of prolonged exposure to predator cues in Gryllodes sigillatus and also tested for the presence of trans-generational effects of this prolonged exposure. I found there were no differences in anti-predator behaviors when measured in subsequent assays compared to control individuals. These results were paired with a comparison of differences in average expressions of behaviors, differences in variances, and behavioral correlations of five closely related cricket species, including G. sigillatus. Our results showed that species differ in average behaviors and plasticity but did not significantly differ in behavioral correlations.
Crop Acreage Response Modeling in North Dakota and Greater Midwest
(North Dakota State University, 2017) Chowdhury, Nazea H Khan
Our research consists of two papers. First paper focus on the trend of North Dakota (ND) crop acreage changes and include economic factors (expected prices of crops, input price, crop yield, revenue of crops) and climate factors (precipitation, minimum and maximum temperature, growing degree days, and palmer drought severity index). We are using Geographic Information System (GIS) database for cropland areas throughout ND for the years 1998 through 2013. But we are using five crops for our analysis. We use Seemingly Unrelated Tobit Left Censored Regression and Monte Carlo Simulation techniques for our analysis. We also include renewable fuel standard dummy (year 2005 and 2007). Findings suggest that prices of crop, yield, revenue, input price significant impact on crop acreage. Marginal effects of crop price increase by $1 to own acreage of barley, corn, soybean, wheat, and oilseeds ranges between 50 to 295 acres, 28 to 572 acres, -24 to 45 acres, -198 to -39 acres, and 7 to 48 acres throughout ND and statistically significant except soybean. Elasticity of own-price to acreage of barley, corn, soybean, wheat, and oilseeds are 1.16%, 1.23%, 0.17%, -0.16%, and 0.53%, respectively, and statistically significant except soybean. Second paper mainly focus on three states ND, South Dakota (SD), and Minnesota (MN) causes of crop acres planted changes due to economic factors as well as weather factors. We are using Seemingly unrelated regression and Monte Carlo Simulation technique for that paper. We produce a balanced panel dataset with annual observations of the planted acreages of each of the five crops in each of the three states, along with the relevant price and yield variables for each crop and pertinent precipitation and temperature variables for each year in each state. Monte Carlo Simulation technique used to calculate own-price elasticity of MN state barley, corn, soybean, wheat, and sunflower to their own acreage are -0.506%, 0.197%, 0.116%, 0.566 %, and 11.34%, respectively; in SD state are -0.739%, 0.312%, 0.290%, 0.309%, and 1.72%, respectively and statistically significant except barley crop elasticity. This research findings will help forecast future agricultural land use trends & crop area response.
Determining Greenhouse Gas Emissions and Nitrogen Dynamics of Solid Beef Manure Applied to Fargo-Clay Soil of the Red River Valley
(North Dakota State University, 2018) Niraula, Suresh
Land application of solid beef manure may prompt greenhouse gases (GHGs) - nitrous oxide (N2O), methane (CH4), and carbon dioxide (CO2) emissions. Nitrogen (N) in manure can also be lost through ammonia volatilization (NH3), leaching (NO3-), denitrification, and erosion. The objectives of this research were to assess the effects of (i) land application of solid beef manure (SM) on emission of GHGs, NH3 volatilization, and corn (Zea mays L.) yield, (ii) soil moisture [(30, 60, and 90% water-holding capacity (WHC)] on GHGs and NH3 emissions from urea and manure application, and (iii) soil temperature (5, 10, 15, and 25°C) on GHGs and NH3 emissions from urea and manure amended Fargo-Ryan silty clay soil of the RRV. The two-year growing season cumulative N2O emission (cN2O) ranged from 0.3 (non-fertilized, NF) to 1.2 (urea only, UO) kg N ha-1. The UO reduced cumulative carbon dioxide (cCO2) by 42% compared to manure N sources. The cumulative CH4 (cCH4) emission ranged from -0.03 to 0.23 kg CH4-C ha-1 CH4-C ha-1, with the highest emission from manure with straw bedding (BM). Manure reduced cNH3 by ~11% compared to UO. Cumulative soil N in 2017 were significantly greater by 11%, respectively, compared to 2016. Nitrogen source did not show any difference in grain yield and grain N uptake in field study. In the laboratory, across WHC levels, 1.01% of the total applied N was lost as N2O at 60% WHC from urea treated soil. Soil CO2 from manure was up to two times the emission from CF treated soils. The cumulative NH3 volatilization loss from soil ranged from 29.4 to 1250.5 µg NH3-N kg−1 soil, with the highest loss from CF amended soils at 30% WHC. In addition, laboratory study showed cumulative GHGs and NH3 emission generally increased with increase in temperature, with the highest emission observed at 25 °C. The results highlight the challenge of meeting crop nutrients demand while reducing GHG emissions by selection of an N source.
Development and Genetic Regulation of the Novel Abdominal Appendages in the Male Sepsid Fly, Themira Biloba
(North Dakota State University, 2013) Herath, Bodini Jeevanthika
Evolutionary novel structures are structures with no known homology. Novel structures often provide a novel function to the organism. Some species of sepsid flies (family Sepsidae) have evolved novel abdominal appendages on the fourth segment in males and are thought to be used during mating to stimulate the female abdomen. However, the necessity of these appendages for the sepsid flies has not been determined, and a little is known about the genetic basis of these structures. Controlled laboratory experiments were conducted to identify the necessity of these appendages in sepsid Themira biloba. Surgical manipulation of the bristle length of the appendages prevented successful mating, and this was observed when the longest bristles were manipulated; reducing the length of short bristles had no effect. These results indicate that bristle length is important for mating success and that the longer bristles are critical. The genetic regulation of the initial specification of the abdominal appendages in sepsids was also investigated. In situ hybridization was done to examine the expression of abdominal-A and Abdominal-B genes in sepsid T. biloba, to determine whether their expression has deviated in forming the appendages. However, the expression domains of these genes are conserved in T. biloba, and are not different from those observed in D. melanogaster. Overall my research emphasizes the necessity of the abdominal appendages, and provides insight into the genetic basis of these novel structures.

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