Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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Item Heifer reproduction strategies: molecular insights into early embryonic development and viability(Montana State University - Bozeman, College of Agriculture, 2022) Manuel, Eden Elizabeth; Chairperson, Graduate Committee: Sarah R. McCoskiCurrent heifer development strategies aim to produce the most fertile female possible. However, in western states heifers commonly transition from high to relatively low nutritional planes following breeding. The effects of maternal nutritive status on the embryonic system are not defined, though this transition is likely contributing to the high rates of early embryonic mortality observed in these animals. This study aimed to decipher the impact of maternal nutrition on day 14 conceptuses collected from beef heifers maintained on ?100% or 70% NRC nutrient requirements. Conceptus RNA was isolated and sequenced to identify differentially expressed genes (DEGs). The DEG set included 771 annotated and 132 novel genes. The biological processes representing the most significant differential expression between conceptuses collected from Low- vs- High groups were hormone metabolic processes (Padj = 0.015), inner ear development (Padj = 0.015), inner ear morphogenesis (Padj = 0.015), hematopoietic progenitor cell differentiation (Padj = 0.015), and tissue morphogenesis (Padj = 0.018). KEGG analysis identified the biological pathways most affected between Low- and High-derived conceptuses. Analysis revealed viral fusion proteins, oocyte meiosis, mineral absorption, and sphingolipid metabolism were significantly affected. Interestingly, the pathways representing the highest number of DEGs were peptidases and inhibitors (n = 22 DEGs), MAPK signaling pathway (n = 17 DEGs), and viral fusion proteins (n = 17). Deeper analysis of the KEGG pathway and gene ontology results linked many of the DEGs to processes related to the cellular differentiation, formation, and function of extraembryonic tissues. While more advanced embryonic patterning and fetal development presented as areas of concern in the literature search, at this time they are not likely factors contributing with the most weight to the high rates of embryonic mortality observed in beef cattle. A majority of the DEGs were related to pathways that control early cell specification events that are necessary for the formation of the trophectoderm and the yolk sac. Data indicates that a decreased plane of maternal nutrition affects the expression of genes associated with critical embryonic events, and likely contributes to increased rates of embryonic mortality by altering the function of extraembryonic tissues.Item Comparing network models of gap gene interaction during Drosophila melanogaster development(Montana State University - Bozeman, College of Letters & Science, 2021) Andreas, Elizabeth Anne; Chairperson, Graduate Committee: Tomas GedeonEarly development of Drosophila melanogaster (fruit fly) facilitated by the gap gene network has been shown to be incredibly robust, and the same patterns emerge even when the process is seriously disrupted. In this thesis we plan to investigate this robustness using a previously developed computational framework called Dynamic Signatures Generated by Regulatory Networks (DSGRN). The principal result of this research has been in extending DSGRN to study how tissue-scale behavior arises from network behavior in individual cells, such as gap gene expression along the anterior-posterior (A-P) axis of the Drosophila embryo. Essentially, we extend DSGRN to study cellular systems where each cell contains the same network structure but operates under a parameter regime that changes continuously from cell to cell. We then use this extension to study the robustness of two different models of the gap gene network by looking at the number of paths in each network that can produce the observed gap gene expression. While we found that both networks are capable or replicating the data, we hypothesize that one network is a better fit than the other. This is significant in two ways; finding paths shows us that the spatial data can be replicated using a single network with different parameters along the A-P axis, and that we may be able to use this extension of DSGRN to rank network models.Item Evaluation of embryo suppression methods for nonnative lake trout in Yellowstone Lake, Yellowstone National Park, Wyoming, USA(Montana State University - Bozeman, College of Letters & Science, 2019) Poole, Alex Stephen; Chairperson, Graduate Committee: Alexander V. ZaleIntroduced Lake Trout Salvelinus namaycush threaten native Yellowstone Cutthroat Trout Oncorhynchus clarkii bouvieri in Yellowstone Lake, Yellowstone National Park. Gill nets have been used to suppress subadult and adult Lake Trout since 1995. Because survival of embryonic and larval life history stages can have profound effects on population dynamics of Lake Trout, suppression at those stages, especially if used in concert with intensive gill netting of older fish, could enhance suppression efforts. Therefore, I conducted controlled laboratory and field experiments to systematically evaluate the effects of a variety of candidate chemical (sodium chloride, calcium carbonate, gelatin, and liquid and powdered rotenone), biological (carcass and carcass analog), and physical (sediment) suppression methods on different developmental stages of Lake Trout embryos and larvae. Liquid and powdered rotenone applications, fish carcass and carcass analog exposures, and sediment deposition significantly increased embryo mortality in laboratory experiments. Sodium chloride, calcium carbonate, and gelatin applications were not effective. In-situ exposure to ground carcass material in Yellowstone Lake resulted in 100% embryo mortality in 14 and 28 kg/m 2 biomass treatments; sediment deposition caused 97% embryo mortality among overwintering incubators. Embryo mortality was probably caused by hypoxic conditions within substrates. Embryo suppression methods differed in their effectiveness, rate at which mortality was achieved, and ease of application. These differences, as well as Lake Trout spawning site characteristics such as depth, contour, fetch, substrate size, interstitial depth, isolation, and presence of non-target organisms ultimately determine which embryo suppression method will be most applicable in a given situation. Nevertheless, implementation of successful embryo suppression techniques evaluated in this study could be used to increase mortality of Lake Trout in Yellowstone Lake. Incorporating effective embryo suppression in an Integrated Pest Management approach has the potential to provide more effective Lake Trout suppression in the long term.Item Quantifying the spatial structure of invasive lake trout in Yellowstone Lake to improve suppression efficacy(Montana State University - Bozeman, College of Letters & Science, 2019) Williams, Jacob Robert; Chairperson, Graduate Committee: Christopher S. GuyConserving Yellowstone Cutthroat Trout by suppressing invasive Lake Trout in Yellowstone Lake is a high priority for Yellowstone National Park natural-resource managers. Insight into the spatial structure of Lake Trout throughout the lake will help increase the efficacy of the Lake Trout suppression program. Lake Trout (N = 578) were surgically implanted with dual acoustic and radio transmitters from 2015 through 2017. Mobile acoustic (boat) and radio (fixed-wing aircraft) telemetry surveys were performed to identify aggregations of Lake Trout. Telemetry surveys occurred during the spawning period (autumn) in 2016 and during the summer and spawning period in 2017. Lake Trout exhibited distinct aggregations during the summer and spawning period. Lake Trout aggregated at nine locations during the summer 2017 and were most frequently located in the West Thumb. Lake Trout aggregated at 22 locations during the spawning period including 12 previously undocumented putative spawning locations. Two aggregations in the West Thumb, Carrington Island and Anglers Bluff, had the highest relative densities of Lake Trout. Aggregations during the summer were generally farther from shore, greater in depth, and more dispersed than aggregations during the spawning period. Targeting locations of Lake Trout, as identified through telemetry, with gill nets was an effective strategy for increasing catch-per-unit-effort. The Lake Trout suppression program is probably altering the behavior of Lake Trout in Yellowstone Lake, which explains the high number of spawning locations and low spawning site fidelity relative to other research studies on Lake Trout spawning behavior. This study provided valuable insight into the spatial structure of Lake Trout in Yellowstone Lake. The areas Lake Trout aggregated will continue to be targeted by gillnetting and novel embryo suppression methods.Item Evaluation of suppression methods targeting non-native lake trout embryos in Yellowstone Lake, Yellowstone National Park, Wyoming, USA(Montana State University - Bozeman, College of Letters & Science, 2017) Thomas, Nathan Andrew; Chairperson, Graduate Committee: Christopher S. GuyNon-native Lake Trout Salvelinus namaycush threaten to extirpate native Yellowstone Cutthroat Trout Oncorhynchus clarkii bouvieri in Yellowstone Lake, Yellowstone National Park. Suppression of Lake Trout in Yellowstone Lake has been ongoing since 1995, primarily by gillnetting. Unfortunately, bycatch of Yellowstone Cutthroat Trout is associated with this removal method, which targets adult and subadult Lake Trout. Alternative methods effective at causing mortality in Lake Trout early life stage(s) could be used simultaneously with gillnetting to improve suppression effectiveness. The vulnerability of salmonid embryos suggest increasing Lake Trout embryo mortality is feasible and because population growth rates are sensitive to age-0 survival an effective embryo suppression method could have population-level effects. Thus, the primary objective of this study was to evaluate the efficacy of methods to increase mortality of Lake Trout embryos. In situ experiments tested the effect of suction dredging, electroshocking, tarping, and Lake Trout carcass deposition on embryo mortality. The secondary objective of this study was to evaluate interstitial water flow using NaCl dry injection to better understand the feasibility of using chemicals for embryo suppression. Concurrent laboratory studies have shown that Lake Trout embryos experience high mortality after chemical exposure. Tarping and suction dredging were not effective at increasing embryo mortality. Electroshocking caused 0.92 mortality of embryos at the substrate surface but only 0.38 at 20 cm depth in the substrate. Lake Trout carcass deposition caused 0.99 mortality of embryos, both at the surface and at 20 cm in the substrate. The direction and rate of interstitial water flow was not consistent and future work on a larger scale is needed to inform the feasibility of chemical suppression. Hypoxic conditions within the carcass sites may have caused embryo mortality. In addition, carbon dioxide CO 2 and hydrogen sulfide H 2S are byproducts of organic matter decomposition that harm developing salmonid embryos. Embryo suppression methods are unlikely to replace traditional Lake Trout suppression methods. However, the success of Lake Trout carcass deposition shows potential for the development of an effective additional suppression method that could be implemented on a large scale.Item Effect of excess degradable intake protein on ovarian steroids, oviductal proteins and early embryonic development in ewes(Montana State University - Bozeman, College of Agriculture, 1998) Weng, JieItem Effect of flunixin meglumine on early embryonic mortality in stressed beef female(Montana State University - Bozeman, College of Agriculture, 2004) Merrill, Melissa Lee; Chairperson, Graduate Committee: Raymond P. Ansotegui.The objectives of this study were to determine if an injection of flunixin meglumine (1.1 mg/kg BW) would affect early embryonic mortality in stressed beef females. Ninety-seven cows were assigned to one of three treatment groups (Experiment 1; El). Treatments were: 1.) control (CON) 2.) transportation stressed (S) and 3.) transportation stressed with flunixin meglumine (SFM). The following year 259 heifers (Experiment 2; E2) and 127 cows (Experiment 3; E3) were assigned to one of four treatments: the three treatments used in El plus control with flunixin meglumine (CONFM). Approximately 14 d following synchronization of estrus and artificial insemination (Al) treatments were applied in all three experiments. Rectal temperatures were recorded and blood samples were taken for serum concentration of progesterone, PGF metabolite, and cortisol. The CON and CONFM (NTS) remained at the ranch while S and SFM (TS) females were transported for 5-6 h. The SFM and CONFM (FM) treatments received an injection of flunixin meglumine (1.1 kg/mg BW, i.m.) while S and CON did not receive an injection of flunixin meglumine (NFM). Females were not exposed to clean-up bulls until after treatment. Transrectal ultrasonography was used to determine Al pregnancy status 33-35 d for heifers and 55-57 d for cows post-AI. Statistics were determined using a 2x2 factorial design. No differences were detected in progesterone or PGFM serum concentration (P>0.10) in El. Serum cortisol concentrations decreased for stressed animals (S and SFM) compared to control animals (CON) between pre- and post-treatment blood samplings (P<0.05) in El. In E2 and E3, serum cortisol concentrations were similar (P>0.10) at the initial blood sampling, increased for TS compared to NTS (P<0.01) at intermediate blood sampling and decreased greater for TS compared to NTS (PO.01) at the final blood sampling. Temperatures were similar for initial temperature collection among treatments of E2 and E3. At the E3 intermediate and E2 final temperature collection, FM was lower (P<0.05) than NFM. The Al pregnancy rates were higher (P=0.03) for FM (63%) than NFM (53%) when combining E2 and E3. The SFM cows had higher (P=0.06; 71%) Al pregnancy rates than S (60%) with CON (63%) being intermediate when combining El, E2, and E3. Final pregnancy rates did not differ. In conclusion, flunixin meglumine decreases the embryonic mortality in beef females that are transportation stressed d 12-14 post-AI but . the stress of handling needs to be explored.