<p>The rationale of this study is to apply light stable isotope chemistry towards investigations that require temporally high-resolution data. High-resolution (or high sampling frequency) data sets, are critical for testing environmental and/or paleoenvironmental hypotheses that seek to explain processes occurring over rapid or short time intervals. The investigation of climate variation (e.g., seasonality, El Niño, deglaciation), animal migration and physiology, and disturbance ecology (e.g., fire, flooding) benefits from the recovery of proxy information at decadal to subannual resolutions. The type of material used also dictates a spatial scale. Herein are presented four studies that utilize high-resolution light stable isotope profiles with contrasting temporal and spatial scales. The first study employs advances in three-dimensional computer-controlled micromilling to recover ~daily to weekly deposited carbonate from small (~1 cm) mollusc shells. Stable oxygen isotope values from freshwater mollusc shells are predictably related to the local environment of growth using previously published temperature-fractionation relationships, providing a paleoclimate record of temperature and precipitation. The second study investigates variation in stable carbon isotope values from Aplodinotus grunniens otoliths, for which high-resolution patterns were critical in assessing metabolic rate as the governing control. The third study employs high-resolution stable oxygen and carbon isotope values to determine chinook salmon (Oncorhynchus tshawytscha) seasonal and ontogenetic migration in Lake Ontario and its tributaries. Lastly, high-resolution stable hydrogen and carbon isotope values of chitin derived from Mexican free-tailed bat (Tadarida brasiliensis) guano are presented, providing a record of abrupt climate change. Thus, this thesis reports on promising new research avenues for paleoclimatology, paleoecology, and modern ecology.

This thesis describes a method for calculating lake evaporation as a proportion of water inputs (E/I) for large surface water bodies, using stable isotope ratios of oxygen (18O/16O) and hydrogen (2H/1H) in water. Evaporation as a proportion of inflow (E/I) is calculated for each Laurentian Great Lake using a new dataset of 516 analyses of δ18O and δ2H in waters sampled from 75 offshore stations during spring and summer of 2007. This work builds on previous approaches by accounting for lake effects on the overlying atmosphere and assuming conservation of both mass and isotopes (18O and 2H) to better constrain evaporation outputs. Results show that E/I ratios are greatest for headwater Lakes Superior and Michigan and lowest for Lakes Erie and Ontario, controlled largely by the magnitude of hydrologic inputs from upstream chain lakes. For Lake Superior, stable isotopes incorporate evaporation over the past century, providing long-term insights to the lake’s hydrology that may be compared to potential changes under a future – expectedly warmer – climate. Uncertainties in isotopically derived E/I are comparable to conventional energy and mass balance uncertainties. Isotope-derived E/I values are lower than conventional energy and mass balance estimates for Lakes Superior and Michigan. The difference between conventional and isotope estimates may be explained by moisture recycling effects. The isotope-based estimates include only evaporated moisture that is also advected from the lake surface, thereby discounting moisture that evaporates and subsequently reprecipitates on the lake surface downwind as recycled precipitation. This shows an advantage of applying an isotope approach in conjunction with conventional evaporation estimates to quantify both moisture recycling and net losses by evaporation. Depth profiles of 18O/16O and 2H/1H in the Great Lakes show a lack of isotopic stratification in summer months despite an established thermocline. These results are indicative of very low over-lake evaporation during warm summer months, with the bulk of evaporation occurring during the fall and winter. This seasonality in evaporation losses is supported by energy balance studies. For Lakes Michigan and Huron, the isotope mass balance approach provides a new perspective into water exchange and evaporation from these lakes. This isotope investigation shows that Lake Michigan and Lake Huron waters are distinct, despite sharing a common lake level. This finding advocates for the separate consideration of Lake Michigan and Lake Huron in future hydrologic studies.

<p>The rationale of this study is to apply light stable isotope chemistry towards investigations that require temporally high-resolution data. High-resolution (or high sampling frequency) data sets, are critical for testing environmental and/or paleoenvironmental hypotheses that seek to explain processes occurring over rapid or short time intervals. The investigation of climate variation (e.g., seasonality, El Niño, deglaciation), animal migration and physiology, and disturbance ecology (e.g., fire, flooding) benefits from the recovery of proxy information at decadal to subannual resolutions. The type of material used also dictates a spatial scale. Herein are presented four studies that utilize high-resolution light stable isotope profiles with contrasting temporal and spatial scales. The first study employs advances in three-dimensional computer-controlled micromilling to recover ~daily to weekly deposited carbonate from small (~1 cm) mollusc shells. Stable oxygen isotope values from freshwater mollusc shells are predictably related to the local environment of growth using previously published temperature-fractionation relationships, providing a paleoclimate record of temperature and precipitation. The second study investigates variation in stable carbon isotope values from Aplodinotus grunniens otoliths, for which high-resolution patterns were critical in assessing metabolic rate as the governing control. The third study employs high-resolution stable oxygen and carbon isotope values to determine chinook salmon (Oncorhynchus tshawytscha) seasonal and ontogenetic migration in Lake Ontario and its tributaries. Lastly, high-resolution stable hydrogen and carbon isotope values of chitin derived from Mexican free-tailed bat (Tadarida brasiliensis) guano are presented, providing a record of abrupt climate change. Thus, this thesis reports on promising new research avenues for paleoclimatology, paleoecology, and modern ecology.

Although the long-term therapeutic benefits of exercise are indisputable, contractile activity may induce divergent adaptations in insulin-resistant vs. insulin-sensitive skeletal muscle. The purpose of this study was to elucidate if the anabolic response following resistance exercise (RE) is altered in myocellular sub-fractions in the face of insulin resistance. Lean (Fa/?) and obese (fa/fa) Zucker rats were assigned to sedentary and RE groups and engaged in either cage rest or four lower-body RE sessions over an 8-d period. Despite obese Zucker rats having significantly smaller hindlimb muscles when compared to age-matched lean rats, basal 24-h fractional synthesis rates (FSR) of mixed protein pools were near normal in distally located muscle groups (gastrocnemius, plantaris, and soleus) and even augmented in those located more proximally (P<0.05; quadriceps). Although 2 x 2 ANOVA indicated a significant main effect of phenotype on mixed FSR in gastrocnemius and soleus (P < 0.05), phenotypic differences were partially accounted for by an exercise effect in the lean phenotype. Interestingly, obese rats exhibited a significant suppression of myofibrillar FSR compared to their lean counterparts (P<0.05; gastrocnemius), while synthesis rates of mitochondrial and cytosolic proteins were normal (gastrocnemius and quadriceps), suggesting a mechanism whereby translation of specific mRNA pools encoding for metabolic enzymes may be favored over other transcripts (e.g., contractile proteins) to cope with nutrient excess in the insulin-resistant state. Immunoblotting of the cytosolic fraction in gastrocnemius muscle indicated an augmented phosporylation of eIF4EBP1 (+ 9%) and p70s6k (+85%) in obese vs. lean rats, but a more potent baseline inhibition of polypeptide-chain elongation as evidenced by an increased phospho/total ratio of eEF2 (+78%) in the obese phenotype. Resistance exercise did not improve synthesis rates of myofibrillar, cytosolic, or mitochondrial proteins to the same extent in obese vs. lean rats, suggesting a desensitization to contractile-induced anabolic stimuli in the insulin-resistant state. We conclude that insulin resistance has diverse effects on protein metabolism, which may vary between muscle groups depending on fiber type distribution, location along the proximodistal body axis, and myocellular sub-fraction, and may blunt the anabolic response to voluntary resistance exercise.

In this work, 22-pole ion trap machines have been applied to investigate protonated water clusters H+(H2O)n (n=4..10) and ionic hydrocarbons CHn+ (n=2..5) at low temperatures. Protonated water clusters H+(H2O)n play an important role in atmospheric chemistry and in interstellar space. The Taipei 22-pole ion trap machine has been applied to kinetic and spectroscopic investigations of these clusters produced from a supersonic expansion in a corona discharge source. Using low-pressure He buffer gas for collisional thermalization, refrigeration of the ion trap by liquid nitrogen allows a good control of the cluster temperature over the range 80K-350K. This method provides an accurate means of determining the dissociation energies of the cluster ions by measuring their dissociation rates as a function of temperature and calculating their internal energies from vibrational frequencies provided by density functional theory. Results of the thermochemical measurements at well-defined cluster temperatures have been given for H+(H2O)n, n=4..10. The feasibility of using the ion trap to acquire temperature-dependent infrared spectra is presented. The deuteration and abstraction reactions of small ionic hydrocarbons CHn+ (n=2..5) with H2, HD and D2 and the subsequent association processes have been explored at temperatures down to 15K in the Chemnitz 22-pole apparatus. The reactions of the investigated ionic species and their isotopic variants are important for understanding ion-molecule processes in the interstellar medium. One of the starting points of the research program was the question whether protonated methane, CH5+, is subject to H-D-exchange in collisions with HD at low temperatures. It turns out that the rate coefficient for this deuteration process is very small, whereas CH3+ deuterates with HD by three subsequent fast exchange reactions to CD3+ at a temperature of 15K. The latter process is very efficient and happens close to the collision limit. The methane cation, CH4+, on the other hand, shows also some interesting features in collisions with H2, HD and D2. It exhibits an inverse temperature dependence with the rate coefficient increasing at least one order of magnitude going from 300K to 15K. Furthermore, reacting with HD at the temperature of 15K, the reaction channel leading to CH5+ is preferred over the D-atom abstraction channel (isotope effect). / Im Rahmen dieser Arbeit wurden zwei Apparaturen mit 22-Pol-Ionenfallen benutzt, um protonierte Wassercluster H+(H2O)n (n=4..10) und kleine ionische Kohlenwasserstoffe CHn+ (n=2..5) bei tiefen Temperaturen zu untersuchen. Die in einer Koronaentladungsquelle erzeugten Cluster H+(H2O)n wurden kinetisch und spektroskopisch untersucht. Dazu wurden sie in einem 22-Pol-Speicher mithilfe eines He-Puffergases auf einer Temperatur zwischen 80K und 350K thermalisiert. Die Bestimmung der Bindungsenergien fuer Cluster der Groesse n=4..10 wird ermoeglicht durch die Messung der temperaturabhaengigen Dissoziationsraten und durch die Ermittlung der inneren Energien mittels berechneter Schwingungsfrequenzen. Temperaturabhaengige IR-Spektren im Bereich der freien OH-Streckschwingung wurden aufgenommen. Die Austausch- und Abstreifreaktionen von ionischen Kohlenwasserstoffen CHn+ (n=2..5) mit H2, HD und D2 und die darauffolgenden Assoziationsprozesse wurden im Temperaturbereich 15K bis 300K untersucht. Es stellt sich z.B. heraus, dass der H-D-Austauschprozess zwischen CH5+ und HD bei 15K sehr langsam ist, wogegen CH3+ mit jeder Kollision einen Austausch ausfuehrt. In der Abstreifreaktion von CH4+ mit Wasserstoffmolekuelen beobachtet man eine inverse Temperaturabhaengigkeit. Dies wird vorlaeufig mit einer laengeren Komplexlebensdauer bei tiefen Temperaturen erklaert.

In quantitative proteomics, many of the LC-MS based approaches employ stable isotopic labelling to provide relative quantitation of the proteome in different cell states. In a typical approach, peptides are first detected and identified by tandem MS scans prior to quantifying proteins. This provides the researcher with a large amount of data that are not useful for quantitation. It is desirable to improve the throughput of current approaches to make proteomics a more routine experiment with an enhanced capacity to detect differentially expressed proteins. This thesis reports the developments towards this goal, including an assessment of the viability of stable dimethyl labelling for comparative proteomic measurements and the evaluation of a dynamic algorithm called Parallel Isotopic Tag Screening (PITS) for the detection of isotopically labelled peptides for quantitative proteomics without the use of tandem MS scans.

This study investigated the critical behaviour of ternary mixtures of DOPC and DPPC, with cholesterol. The properties of model membranes such as these are studied in order to provide insight into aspects of complex biological systems. Experiments were performed using the Jeener echo, a static solid-state NMR technique, however no information about the critical phenomena was obtained. Conversely, the sideband linewidths measured from 2H MAS NMR are sensitive to temperature and dependent upon the phase behaviour. By fitting the linewidth data to an equation from Suwelack et al. (J. Chem. Phys., 1980; 73(6):2559-2569), the critical temperature and the critical exponent for the correlation length of the system were calculated. The critical exponent values obtained from these samples ranged between νc = 0.65 and νc = 1.2, which encompasses the critical exponents for both the 2D and 3D Ising models within error. The universality class for these model membranes cannot be unambiguously assigned yet.

Migration acts as a selective force on the ecology and evolutionary trajectory of species, as well as presenting fundamental challenges for conservation. My thesis examines the impact of migration by exploring patterns of differentiation among and within migratory and non-migratory populations of the Loggerhead Shrike (Lanius ludovicianus). First, I use morphological, genotypic, stable isotope and leg band recovery data to quantify migratory connectivity in the species. Comparison across markers reveals a generally concordant pattern of moderate connectivity to the Gulf Coast, but overall mixing among populations on the wintering grounds. Combining data from multiple markers in a Bayesian framework improves the resolution of assignment of wintering birds to a breeding ground origin. Information on the species’ migratory patterns provides an explicit framework for interpreting patterns of genetic and ecological variation. I test two hypotheses regarding the interaction of gene flow and migratory habit: (1) migration facilitates gene flow; and (2) gene flow will occur most often along the axis of migration. Genetic population structure in migratory populations is weaker than in non-migratory populations, with gene flow facilitated by dispersal movements of females and first year breeders. As predicted, gene flow occurs most often along the north-south axis of migration, likely due either to opportunistic settling of dispersers or potentially, pairing on the wintering grounds. I investigate variation in the extent and scheduling of moult in relation to underlying genetic differences among populations, age, sex, body size, food availability and migratory habit. I find a pattern of interrupted moult across migratory populations, which may represent a trade-off between time allocated to breeding versus molt and migration. Loggerhead Shrikes in eastern and more southerly migratory populations undergo a greater extent of their moult on the breeding grounds and non-migratory individuals undergo a more extensive pre-formative moult than migratory individuals. I interpret this as suggesting a trade-off between resources allocated to molt versus those required for reproduction. / Thesis (Ph.D, Biology) -- Queen's University, 2011-01-25 15:54:36.593

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This thesis describes a method for calculating lake evaporation as a proportion of water inputs (E/I) for large surface water bodies, using stable isotope ratios of oxygen (18O/16O) and hydrogen (2H/1H) in water. Evaporation as a proportion of inflow (E/I) is calculated for each Laurentian Great Lake using a new dataset of 516 analyses of δ18O and δ2H in waters sampled from 75 offshore stations during spring and summer of 2007. This work builds on previous approaches by accounting for lake effects on the overlying atmosphere and assuming conservation of both mass and isotopes (18O and 2H) to better constrain evaporation outputs. Results show that E/I ratios are greatest for headwater Lakes Superior and Michigan and lowest for Lakes Erie and Ontario, controlled largely by the magnitude of hydrologic inputs from upstream chain lakes. For Lake Superior, stable isotopes incorporate evaporation over the past century, providing long-term insights to the lake’s hydrology that may be compared to potential changes under a future – expectedly warmer – climate. Uncertainties in isotopically derived E/I are comparable to conventional energy and mass balance uncertainties. Isotope-derived E/I values are lower than conventional energy and mass balance estimates for Lakes Superior and Michigan. The difference between conventional and isotope estimates may be explained by moisture recycling effects. The isotope-based estimates include only evaporated moisture that is also advected from the lake surface, thereby discounting moisture that evaporates and subsequently reprecipitates on the lake surface downwind as recycled precipitation. This shows an advantage of applying an isotope approach in conjunction with conventional evaporation estimates to quantify both moisture recycling and net losses by evaporation. Depth profiles of 18O/16O and 2H/1H in the Great Lakes show a lack of isotopic stratification in summer months despite an established thermocline. These results are indicative of very low over-lake evaporation during warm summer months, with the bulk of evaporation occurring during the fall and winter. This seasonality in evaporation losses is supported by energy balance studies. For Lakes Michigan and Huron, the isotope mass balance approach provides a new perspective into water exchange and evaporation from these lakes. This isotope investigation shows that Lake Michigan and Lake Huron waters are distinct, despite sharing a common lake level. This finding advocates for the separate consideration of Lake Michigan and Lake Huron in future hydrologic studies.