Metabolic Scaling Physiology and the Uptake, Elimination and Toxicity of TFM (3-trifluoromethyl-4-nitrophenol) to Invasive Sea Lampreys (Petromyzon marinus)

Sea lampreys (Petromyzon marinus) have a complex life cycle that involves a parasitic phase in which they feed on the blood and bodily fluids of large piscivorous fishes. Following the invasion of the Great Lakes by sea lampreys in the early 20th century, sea lamprey parasitism contributed to major declines in the populations of commercial and sports fisheries in that basin. The lampricide 3-trifluoromethyl-4-nitrophenol (TFM), developed in the late 1950s,is now routinely applied to tributaries of the Great Lakes to control sea lamprey populations. This lampricide is selectively toxic to larval sea lampreys, which typically reside as burrow-dwelling filter-feeders in streams. Although the TFM concentrations commonly applied to streams and rivers is 1.2 - 1.5 times the 9 h LC99.9 (minimum lethal concentration; MLC)of the larvae, surviving residual sea lamprey may be observed after treatments. The underlying causes for “residuals” are poorly understood, however. The main goal of my M.Sc. thesis was to determine how body size and life stage influenced TFM uptake, excretion andsurvival of larval sea lampreys following TFM exposure. Because rates of oxygen consumption (ṀO2) are inversely proportional to body size in animals, I predicted that correspondingly lower rates of ventilation would result in lower rates of TFM uptake and greater TFM tolerance in larger compared to smaller larval sea lampreys. As predicted, smaller lampreys had exponentially higher rates of ṀO2 and TFM uptake compared to larger animals. I alsopredicted that due to higher metabolic demands, more activepost-metamorphic sea lampreys would have higher TFM uptake rates compared to larval sea lampreys. Surprisingly, both ṀO2 and TFM uptake rates were similar in size matched larval and post-metamorphic sea lampreys. Body mass wasalso correlated with TFM elimination, following intraperitoneal injection of TFM, but there were no differences in the TFM clearance rates between larval and post-metamorphic sea lampreys. Finally, toxicity tests indicated that larval sea lamprey with greater mass and condition factor (CF) were able to survive exposure to TFM longer than smaller sea lampreys. Collectively, these results suggest that large larval sea lampreys may be more tolerant to TFM, suggesting that streams containing high densities of large larvae may be at risk for increased residual sea lamprey following TFM treatment. Thus, it would be advisable to take precautions to reduce the chances of residuals when TFM is applied tosteams with high densities of large larvae

Development of a One-Pot Allylation and Claisen Rearrangement of Acetaminophen by Applying Microwave Radiation

The Claisen rearrangement is a widely applicable organic reaction that involves the shift of a sigma bond across the pi-system of an allyl vinyl ether to produce allylated phenols. In this project, we aim to develop a microwave assisted allylation of a phenol, followed by a subsequent Claisen rearrangement in one pot. The goals of this project are three-fold. First, we aim to accelerate these reactions using microwave assisted organic synthesis because to date, microwave technology has been sparsely used in Claisen chemistry. Second, we aim to perform these reactions in a single pot, enhancing the simplicity and elegance of the reaction. Finally, our research group has an interest in allylated phenols given the allyl group can be used to attach the ring to other molecules. Acetaminophen was chosen as a model phenol to test the chemistry. As a result, this also affords derivatives which like acetaminophen, could have analgesic properties. Initial studies reveal that the Claisen rearrangement of allylated acetaminophen requires a reaction time of under ten minutes in the microwave compared to hours when performed under reflux. Further optimization of other components of the reaction are ongoing

Activity-Dependent Modulation of Neural Circuit Synaptic Connectivity

In many nervous systems, the establishment of neural circuits is known to proceed via a two-stage process; (1) early, activity-independent wiring to produce a rough map characterized by excessive synaptic connections, and (2) subsequent, use-dependent pruning to eliminate inappropriate connections and reinforce maintained synapses. In invertebrates, however, evidence of the activity-dependent phase of synaptic refinement has been elusive, and the dogma has long been that invertebrate circuits are “hard-wired” in a purely activity-independent manner. This conclusion has been challenged recently through the use of new transgenic tools employed in the powerful Drosophila system, which have allowed unprecedented temporal control and single neuron imaging resolution. These recent studies reveal that activity-dependent mechanisms are indeed required to refine circuit maps in Drosophila during precise, restricted windows of late-phase development. Such mechanisms of circuit refinement may be key to understanding a number of human neurological diseases, including developmental disorders such as Fragile X syndrome (FXS) and autism, which are hypothesized to result from defects in synaptic connectivity and activity-dependent circuit function. This review focuses on our current understanding of activity-dependent synaptic connectivity in Drosophila, primarily through analyzing the role of the fragile X mental retardation protein (FMRP) in the Drosophila FXS disease model. The particular emphasis of this review is on the expanding array of new genetically-encoded tools that are allowing cellular events and molecular players to be dissected with ever greater precision and detail

Taste Preference Assay for Adult Drosophila

Olfactory and gustatory perception of the environment is vital for animal survival. The most obvious application of these chemosenses is to be able to distinguish good food sources from potentially dangerous food sources. Gustation requires physical contact with a chemical compound which is able to signal through taste receptors that are expressed on the surface of neurons. In insects, these gustatory neurons can be located across the animal's body allowing taste to play an important role in many different behaviors. Insects typically prefer compounds containing sugars, while compounds that are considered bitter tasting are avoided. Given the basic biological importance of taste, there is intense interest in understanding the molecular mechanisms underlying this sensory modality. We describe an adult Drosophila taste assay which reflects the preference of the animals for a given tastant compound. This assay may be applied to animals of any genetic background to examine the taste preference for a desired soluble compound

Thiol-disulfide Interchange in Formation of β-Lactoglobulin-κ-Casein Complex

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Thickness-dependent thermal properties of amorphous insulating thin films measured by photoreflectance microscopy

In this work, we report on the measurement of the thermal conductivity of thin insulating films of SiO2 obtained by thermal oxidation, and Al2O3 grown by atomic layer deposition (ALD), both on Si wafers. We used photoreflectance microscopy to determine the thermal properties of the films as a function of thickness in the 2 nm to 1000 nm range. The effective thermal conductivity of the Al2O3 layer is shown to decrease with thickness down to 70% for the thinnest layers. The data were analyzed upon considering that the change in the effective thermal conductivity corresponds to an intrinsic thermal conductivity associated to an additional interfacial thermal resistance. The intrinsic conductivity and interfacial thermal resistance of SiO2 were found to be equal to 0.95 W/m·K and 5.1 × 10− 9 m2K/W respectively; those of Al2O3 were found to be 1.56 W/m·K and 4.3 × 10− 9 m2K/W

The translational regulator dFMRP interacts with epidermal growth factor receptor to regulate apoptosis in Drosophila

poster abstractPosttranscriptional gene regulation is required for all aspects of cellular and tissue development and is a major mechanism underlying many diseases ranging from neurological disorders to cancer. The translational repressor fragile x mental retardation protein (FMRP) is ubiquitously expressed throughout development but is silenced in Fragile X Syndrome, an autism spectrum disorder. Interestingly, high levels of FMRP have recently been identified in human metastatic breast cancer. FMRP overexpression in these patients is directly correlated with increased lung metastasis suggesting a direct role for translational regulation both in cell proliferation and in invasive cell migration. Interestingly, however, FMRP can promote both proliferation and apoptosis. To dissect FMRP’s role in cancer development and progression, we are exploiting the powerful genetic system of Drosophila. Drosophila is an excellent model organism for human diseases associated with FMRP due to the strong evolutionary conservation of the fragile x mental retardation gene 1 which encodes this protein. dFMRP was overexpressed in the Drosophila imaginal wing disc, an epithelial tissue model. Contrary to a role in proliferation, overexpression of dFMRP leads to obvious cell loss in the adult wing and an increase in apoptotic markers. Using a combinatorial genetic screen, we have identified genes which are able to suppress this apoptotic phenotype and thus may be important for FMRP-­‐dependent tumorigenesis. Our focus is now on the epidermal growth factor receptor (EGFR) signaling pathway since blocking this mechanism is able to completely rescue the dFMRP-­‐overexpression wing defects. Clonal analysis reveals that dFMRP overexpressing cells survive their dFMRP-­induced apoptotic programming when co-­‐expressing a dominant negative form of EGFR. Additional clonal analyses are being used to explore the potential significance of this survival on tumor formation and metastasis

Iron deficiency reduces synapse formation in the Drosophila clock circuit

Iron serves as a critical cofactor for proteins involved in a host of biological processes. In most animals, dietary iron is absorbed in enterocytes and then disseminated for use in other tissues in the body. The brain is particularly dependent on iron. Altered iron status correlates with disorders ranging from cognitive dysfunction to disruptions in circadian activity. The exact role iron plays in producing these neurological defects, however, remains unclear. Invertebrates provide an attractive model to study the effects of iron on neuronal development since many of the genes involved in iron metabolism are conserved, and the organisms are amenable to genetic and cytological techniques. We have examined synapse growth specifically under conditions of iron deficiency in the Drosophila circadian clock circuit. We show that projections of the small ventrolateral clock neurons to the protocerebrum of the adult Drosophila brain are significantly reduced upon chelation of iron from the diet. This growth defect persists even when iron is restored to the diet. Genetic neuronal knockdown of ferritin 1 or ferritin 2, critical components of iron storage and transport, does not affect synapse growth in these cells. Together, these data indicate that dietary iron is necessary for central brain synapse formation in the fly and further validate the use of this model to study the function of iron homeostasis on brain development