Horticulture for Pollinator Conservation

Pollinators worldwide are declining. Consequently, the agricultural and ecological services these insects provide are in danger of being lost. Land use intensification, via urbanization, has greatly influenced this decline in pollinators. Luckily, through targeted horticultural practices, stable populations of pollinators can be sustained within urban areas. The horticultural practices of planting diverse floral resources and managing pollinator habitat in urban areas can sustain these populations. Two studies were conducted with the intent to identify horticultural knowledge gaps that could be reduced to aid in pollinator conservation efforts. First, a study to compare Nebraska native and non-native ornamental plants was conducted. This study set out to understand the impact a plant’s native status has on its attractiveness to urban bees. Three pairings of plant species with similar flowering attributes were sampled for bees. Each pairing included one native plant and one non-native plant. The average abundance and diversity of bees per observation was compared. Results between pairings were mixed, suggesting the native origin of a plant species has little to no impact on attractiveness to urban bees. A weak correlation was discovered between various plant attributes and the abundance and diversity of foraging bees, suggesting plant qualities apart from native origin may be at play. Our recommendation is to use a diverse palette of native and non-native plant species that includes select plant species that attract specialist bee species. Second, a nationwide survey of horticulture retail employees was conducted. This survey aimed to assess the knowledge retailers possess pertaining to pollinators and to determine what plant and landscape recommendations they are giving customers for pollinator conservation. Responses were analyzed with demographics to determine discrepancies in knowledge among specific groups of employees. Overall, pollinator knowledge and conservation recommendations were accurate, but room for improvement was identified, suggesting opportunities for educational outreach. There still is much work to be done to improve horticulture practices that aim to conserve pollinators. These two studies serve as a starting point for future research projects. Horticulture can be an extremely useful method of promoting and increasing pollinator health. By conducting and implementing further scientific research, this scientific discipline can be used more effectively. Advisors: Douglas Golick & Kim Tod

Essential oil effects on rumen fermentation, animal performance, and meat quality of beef steers

"December 2013.""A Thesis presented to the Faculty of the Graduate School University of Missouri--Columbia In Partial Fulfillment of the Requirements for the Degree Master of Science."Thesis advisors: Dr. Monty S. Kerley and Dr. Bryon Wiegand.Efficiency in ruminants has historically been improved by using antibiotics and ionophores to alter rumen fermentation. Nutritionists, however, have begun searching for alternative rumen modifiers due to the negative attention received by non-therapeutic antibiotic use. Plant extracts, like essential oils, are being explored as a potential alternative to alter fermentation and improve growth and efficiency in ruminants. Essential oils are naturally occurring, secondary metabolites that can be distilled or extracted from most plants and possess antimicrobial properties. Next Enhance® (NE, Novus International Inc.) is comprised of garlic (diallyl disulfide) and cinnamon (cinnamaldehyde) extracts; both have demonstrated the ability to modify fermentation. A series of experiments was conducted to determine how feeding NE affects in vitro fermentation, site and extent of nutrient digestion, feedlot performance, carcass traits, meat quality, and consumer sensory characteristics of LM steaks from beef steers. The first experiment in this thesis examined how feedlot steer performance and carcass traits were affected by NE feeding. ADG and G:F were improved early in the feeding period by 150 mg·hd-1 ·d-1 targeted NE inclusion. DMI, overall ADG, and overall G:F were not affected by NE inclusion. All NE levels improved dressing percent, 12th rib backfat, LM area, and calculated USDA yield grade. Steers fed 150 mg·hd-1 ·d-1 NE yielded carcasses worth nearly $30 more than control steers. LM steaks were obtained from five head/treatment and used to evaluate meat quality and consumer sensory characteristics. L*, a*, and b* color values were not affected by TRT on d 0 or 14. Cook loss percent was increased when low NE levels were fed but decreased by high NE doses. Warner-Bratzler shear force, and percent drip loss, moisture, and fat were not affected by NE inclusion. A consumer sensory panel reported no difference in beef steer LM steak organoleptic properties due to NE. NE inclusion at 150-300 mgIncludes bibliographical references (pages 73-80)

Kerguelen Plateau Drift Deposits: outstanding high-resolution chronicle of Cenozoic climatic and oceanographic changes in the southern Indian Ocean

Cruise Leg SO272 with RV SONNE, leaving Port Louis, Mauritius, on January 11 2020, returning to Cape Town, South Africa, on March 4 2020, comprised seismic reflection studies and geological sampling of the Kerguelen Plateau in the southern part of the Indian Ocean. The Kerguelen Plateau rises up 2000 m above the surrounding seafloor and hence forms an obstacle for the flow of the Antarctic Circumpolar Current (ACC) and the Antarctic Bottomwater (AABW). The ACC is strongly deviated in its flow towards the north. A branch of the AABW flows northwards along the eastern flank of the plateau thereby shaping sediment drifts. A detailed study and analysis of the structure of the Labuan Basin and the central Kerguelen Plateau via seismic data and a correlation with results from DSP Leg 120 Sites 748, 750, and 751 was needed to supply information on the Cretaceous and Tertiary development of the AABW and its influence on the path of the Antarctic Circumpolar Current, This in turn will allow conclusions on the development of the East Antarctic Ice Sheet. Seismic profiles were gathered, which capture the structure of the Labuan Basin and the Kerguelen Plateau to basement and image sediment drifts. In total ~4000 km of high resolution seismic reflection data were recorded. Bathymetric and Parasound data were recorded parallel to the seismic profiling. To complement the seismic studies and provide ages of the outcropping sediment geological samples were retrieved at 11 locations using a gravity corer and multi-corer. Both datasets will form the base for an IODP proposal

Orbital forcing of the Paleocene and Eocene carbon cycle

This is the final version of the article. Available from the publisher via the DOI in this record.Multimillion-year proxy records across the Paleocene and Eocene show prominent variations on orbital time scales. The cycles, which have been identified at various sites across the globe, preferentially concentrate spectral power at eccentricity and precessional frequencies. It is evident that these cycles are an expression of changes in global climate and carbon cycling paced by astronomical forcing. However, little is currently known about the link between orbital forcing and the carbon cycle-climate system and the amplitude of associated atmospheric CO2 variations. Here we use simple and complex carbon cycle models to explore the basic effect of different orbital forcing schemes and noise on the carbon cycle. Our primary modeling target is the high-resolution, ∼7.7 Myr long, benthic isotope record at Ocean Drilling Program Site 1262 in the South Atlantic. For direct insolation forcing (as opposed to artificial eccentricity-tilt-precession), one major challenge is understanding how the system transfers spectral power from high to low frequencies. We discuss feasible solutions, including insolation transformations analogous to electronic AC-DC conversion (DC’ing). Regarding mechanisms, we focus on tropical insolation and a long-term carbon imbalance in terrestrial organic burial/oxidation but do not rule out other scenarios. Our analysis shows that high-latitude mechanisms are unlikely drivers of orbitally paced changes in the late Paleocene-early Eocene (LPEE) Earth system. Furthermore, we provide constraints on the origin and isotopic composition of a possible LPEE cyclic carbon imbalance/source responding to astronomical forcing. Our simulations also reveal a mechanism for the large 13C-eccentricity lag at the 400 kyr period observed in Paleocene, Oligocene, and Miocene sections. We present the first estimates of orbital-scale variations in atmospheric CO2 during the late Paleocene and early EoceneThis research was supported by U.S. NSF grants OCE12-20615 and OCE16-58023 to R.E.Z. and J.C.Z. and the Deutsche Forschungsgemeinschaft (DFG) to T.W

A high‐resolution benthic stable‐isotope record for the South Atlantic: implications for orbital scale changes in Late Paleocene–Early Eocene climate and circulation

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.The Late Paleocene and Early Eocene were characterized by warm greenhouse climates, punctuated by a series of rapid warming and ocean acidification events known as “hyperthermals”, thought to have been paced or triggered by orbital cycles. While these hyperthermals, such as the Paleocene Eocene Thermal Maximum (PETM), have been studied in great detail, the background low-amplitude cycles seen in carbon and oxygen-isotope records throughout the Paleocene–Eocene have hitherto not been resolved. Here we present a 7.7 million year (myr) long, high-resolution, orbitally-tuned, benthic foraminiferal stable-isotope record spanning the late Paleocene and early Eocene interval (∼52.5–60.5 Ma) from Ocean Drilling Program (ODP) Site 1262, South Atlantic. This high resolution (∼2–4 kyr) record allows the changing character and phasing of orbitally-modulated cycles to be studied in unprecedented detail as it reflects the long-term trend in carbon cycle and climate over this interval. The main pacemaker in the benthic oxygen-isotope (δ18O) and carbon-isotope (δ13C) records from ODP Site 1262, are the long (405 kyr) and short (100 kyr) eccentricity cycles, and precession (21 kyr). Obliquity (41 kyr) is almost absent throughout the section except for a few brief intervals where it has a relatively weak influence. During the course of the Early Paleogene record, and particularly in the latest Paleocene, eccentricity-paced negative carbon-isotope excursions (δ13C, CIEs) and coeval negative oxygen-isotope (δ18O) excursions correspond to low carbonate (CaCO3) and coarse fraction (%CF) values due to increased carbonate dissolution, suggesting shoaling of the lysocline and accompanied changes in the global exogenic carbon cycle. These negative CIEs and δ18O events coincide with maxima in eccentricity, with changes in δ18O leading changes in δ13C by ∼6 (±5) kyr in the 405-kyr band and by ∼3 (±1) kyr in the higher frequency 100-kyr band on average. However, these phase lags are not constant, with the lag in the 405-kyr band extending from ∼4 (±5) kyr to ∼21 (±2) kyr from the late Paleocene to the early Eocene, suggesting a progressively weaker coupling of climate and the carbon-cycle with time. The higher amplitude 405-kyr cycles in the latest Paleocene are associated with changes in bottom water temperature of 2–4 °C, while the most prominent 100 kyr-paced cycles can be accompanied by changes of up to 1.5 °C. Comparison of the 1262 record with a lower resolution, but orbitally-tuned benthic record for Site 1209 in the Pacific allows for verification of key features of the benthic isotope records which are global in scale including a key warming step at 57.7 Ma.Thanks to Alexis Kersey for picking foraminifera and assisting with sample processing (at UCSC), and to Walker Weir, Alejandro Aguilar, and Phillip Staudigel for lab assistance, and to Dyke Andreasen and Chih-Ting Hsieh for stable-isotope support (UCSC). Thanks to Barbara Donner (MARUM) for coordinating foraminifera picking, and to Monika Segl and her team (MARUM) for stable-isotope analyses. We thank Roy Wilkens (Hawaii) for core images analysis. Sediment samples were supplied by the Ocean Drilling Program. Funding for this project was provided by NSF grant (grant number EAR-0628719) to J.Z. and DFG grants (RO 1113/2 through RO 1113/4) to U.R

Kinetic and Thermodynamic Contributions to an Intermolecular Mechanism of Subunit Communication: Coordination of Pyruvate Carboxylase Activity Among Spatially Distinct Active Sites

Catalysis occurring in a multifunctional enzyme at spatially distinct active sites is controlled by an array of factors, including the structure of the enzyme, ligand binding, and productive interaction of substrates to facilitate turnover. Successful execution of the catalytic cycle is partially dependent upon the ability of spatially and functionally discrete active sites to communicate with one another, as well as with any allosteric regulatory regions of the enzyme. This type of long-range communication typically manifests measurable effects on substrate binding or product release. In the case of pyruvate carboxylase (PC), pyruvate binding to the carboxyl transferase (CT) domain induces translocation of the biotin carboxyl carrier (BCCP) domain and subsequently increases the rate of Pi release in the biotin carboxylase (BC) domain. While the kinetic mechanism and structural arrangement of the PC tetramer has largely been elucidated, the source of the intermolecular signals required to facilitate catalysis between distinct active sites remains unclear. The BC and CT domain active sites necessary to produce one oxaloacetate are located on two separate polypeptide chains, while binding of acetyl-CoA in its pocket formed between the allosteric domain and the BC domain is required for stimulation of the overall catalytic rate. In metabolic regulatory enzymes such as PC, it is essential to understand not only the overall mechanism of intersubunit communication, but also the thermodynamic driving forces behind each individual ligand relationship in order to piece together the network of amino acids and subunit domains that is responsible for the dramatic stimulatory response elicited upon binding of acetyl-CoA, the enzyme's essential allosteric activator. Ultimately, this would allow for elucidation of the molecular regulatory mechanism of PC and for subsequent development of therapeutic strategies to target the chronic hyperglycemia associated with its uncontrolled activity in Type 2 diabetics. To address how pyruvate occupancy in the CT domain impacts the behavior of other domains, we generated mixed hybrid tetramers using mutants of the catalytically relevant residues Glu218 (in the BC domain) and Thr882 (in the CT domain) and measured both the pyruvate carboxylation and inorganic phosphate release activities. Our results, which compared the apparent Ka pyruvate for pyruvate-stimulated Pi release catalyzed by the T882S:E218A(1:1) hybrid tetramer to that of the wild-type and the T882S homotetramer, were consistent with an intermolecular mechanism of subunit communication, whereby pyruvate binding at the T882S CT domain was responsible for inducing translocation of the E218A BCCP domain within the same face of the tetramer. We also determined the thermodynamic-linkage of each ligand of PC, that is, the extent to which the presence of one bound substrate or effector positively or negatively influences enzyme turnover in the presence of saturating and subsaturating concentrations of another. The ability of either MgATP or pyruvate to increase the affinity of PC for the other is observed in the presence of acetyl-CoA, while this relationship is entirely lost in its absence. These results have the potential to further reveal the nature of intersubunit communication, in that the enzyme's spatially distinct active sites, even in the presence of the preferred substrates, cannot communicate or coordinate productive catalytic coupling in the absence of the activator. Long-term implications of this proposal include determination of the consequences of imbalanced metabolic flux, such as that observed in Type 2 Diabetes, on the regulatory mechanism and catalytic activity of PC in the liver

Some comparison theorems for weak nonnegative splittings of bounded operators

AbstractThe comparison of the asymptotic rates of convergence of two iteration matrices induced by two splittings of the same matrix has arisen in the works of many authors. In this paper we derive new comparison theorems for weak nonnegative splittings and weak splittings of bounded operators in a general Banach space and rather general cones, and in a Hilbert space, which extend some of the results obtained by Woźnicki (Japan J. Indust. Appl. Math. 11(1994) 289–342) and Marek and Szyld (Numer. Math. 44(1984) 23–35). Furthermore, we present new theorems also for bounded operator which extend some results by Csordas and Varga (Numer. Math. 44. (1984) 23–35) for weak nonnegative splittings of matrices