Matching Items (68)

137132-Thumbnail Image.png

Response of Daphnia feeding rate to food C:P ratio: a test for the ""stoichiometric knife edge"" mechanism

Description

It is well known that deficiencies in key chemical elements (such as phosphorus, P) can reduce animal growth; however, recent empirical data have shown that high levels of dietary nutrients

It is well known that deficiencies in key chemical elements (such as phosphorus, P) can reduce animal growth; however, recent empirical data have shown that high levels of dietary nutrients can also reduce animal growth. In ecological stoichiometry, this phenomenon is known as the "stoichiometric knife edge," but its underlying mechanisms are not well-known. Previous work has suggested that the crustacean zooplankter Daphnia reduces its feeding rates on phosphorus-rich food, causing low growth due to insufficient C (energy) intake. To test for this mechanism, feeding rates of Daphnia magna on algae (Scenedesmus acutus) differing in C:P ratio (P content) were determined. Overall, there was a significant difference among all treatments for feeding rate (p < 0.05) with generally higher feeding rates on P-rich algae. These data indicate that both high and low food C:P ratio do affect Daphnia feeding rate but are in contradiction with previous work that showed that P-rich food led to strong reductions in feeding rate. Additional experiments are needed to gain further insights.

Contributors

Agent

Created

Date Created
  • 2014-05

136646-Thumbnail Image.png

Symbiotic state & reproduction in the giant green sea anemone Anthopleura xanthogrammica

Description

The giant green sea anemone, Anthopleura xanthogrammica, hosts two different endosymbiotic algae. One is a unicellular chlorophyte, Elliptochloris marina; the other is Symbiodinium muscatinei, a dinoflagellate. Hosting these different symbionts

The giant green sea anemone, Anthopleura xanthogrammica, hosts two different endosymbiotic algae. One is a unicellular chlorophyte, Elliptochloris marina; the other is Symbiodinium muscatinei, a dinoflagellate. Hosting these different symbionts influences the life history strategy of A. xanthogrammica's congener A. elegantissima, directly impacting its reproductive strategy (asexual vs. sexual). My study sought to examine whether the type and density of symbiont also affects the reproductive condition of A. xanthogrammica, which reproduces only sexually. Gonad development was measured in anemones from Slip Point, Clallam Bay, WA and Tongue Point, WA along with symbiont type and density per mg of anemone protein. The results indicate a trend towards brown anemones having more developed gonads, especially in males. This may mean that A. xanthogrammica anemones that host zooxanthellae are more reproductively fit than zoochlorellate anemones. Thus, it may be favorable for anemones to host zooxanthellae. This is especially true in summer months when the high temperatures and mid-day low tides coincide with the period of most rapid gonad development.

Contributors

Agent

Created

Date Created
  • 2015-05

136921-Thumbnail Image.png

Characterization of a Polyclonal Antibody Specific for Synechococcus WH8102 Plastoquinol Terminal Oxidase.

Description

Photosynthesis is a critical process that fixes the carbon utilized in cellular respiration. In higher plants, the immutans gene codes for a protein that is both involved in carotenoid biosynthesis

Photosynthesis is a critical process that fixes the carbon utilized in cellular respiration. In higher plants, the immutans gene codes for a protein that is both involved in carotenoid biosynthesis and plastoquinol oxidation (Carol et al 1999, Josse et al 2003). This plastoquinol terminal oxidase (PTOX) is of great interest in understanding electron flow in the plastoquinol pool. In order to characterize this PTOX, polyclonal antibodies were developed. Expression of Synechococcus WH8102 PTOX in E. coli provided a useful means to harvest the protein required for antibody production. Once developed, the antibody was tested for limit of concentration, effectiveness in whole cell lysate, and overall specificity. The antibody raised against PTOX was able to detect as low as 10 pg of PTOX in SDS-PAGE, and could detect PTOX extracted from lysed Synechococcus WH8102. The production of this antibody could determine the localization of the PTOX in Synechococcus.

Contributors

Agent

Created

Date Created
  • 2014-05

137539-Thumbnail Image.png

Studying Plankton Community Dynamics in the Sargasso Sea Using Microscopy and Molecular Techniques

Description

The phytoplankton communities in the open oceans are dominated by picophytoplankton (0.7-2µm) and nanophytoplankton (3-5µm). Studying the community dynamics of these phytoplankton is important to learn about their role

The phytoplankton communities in the open oceans are dominated by picophytoplankton (0.7-2µm) and nanophytoplankton (3-5µm). Studying the community dynamics of these phytoplankton is important to learn about their role in the carbon cycle and food web of the oceans. Dilution experiments were used, along with microscopy and molecular techniques, to determine abundance, biomass and phytoplankton growth and grazing rates in the oligotrophic Sargasso Sea (western North Atlantic subtropical gyre) around the Bermuda Atlantic Time Series Station (BATS) in the summer of 2012. With low biomass and chlorophyll a, the Sargasso Sea appears to be unproductive at first glance, but I found that pico- and nanophytoplankton have high instantaneous growth rates that are balanced by the high grazing rates of microzooplankton.
Mesoscale eddies are important features in the Sargasso Sea that can increase or decrease the available nutrients in the euphotic zone. Two different mesoscale eddies were sampled: an anti-cyclonic eddy and the BATS station which was located at the edge of a cyclonic eddy. The results indicated that BATS had overall higher instantaneous growth (µ between 0.1 d-1 and 3.7 d-1) and grazing rates on pico- and nanophytoplankton, as well as diatoms, compared to the anti-cyclonic eddy (µ between 0.2 d-1 and 3 d-1). I also determined taxon-specific rates using quantitative polymerase chain reaction (qPCR) for the order Mamiellales, one of the smallest representatives of the abundant prasinophytes. This method yielded surprisingly high growth (9.7 d-1 ) and grazing rates (-8.2 d-1) at 80m for BATS. The euphotic zone (~100m) integrated biomass of all phytoplankton did not vary significantly between BATS (379 mg C m-2) and the anti-cyclonic eddy (408 mg C m-2) and the net growth rates at both locations were very close to zero for most of the groups. Although the biomass and net growth rates did not vary greatly between the two locations, the high instantaneous growth and grazing rates of pico- and nano-eukaryotic phytoplankton indicate an increase in the rate of the marine microbial food web, or microbial loop, compared to the anti-cyclonic eddy. This could have been due to the input of new nutrients in the edge of the cyclonic eddy at BATS. Thus, my study suggests that mesoscale variability is of considerable importance for the dynamics of the phytoplankton community and their role in the microbial loop. Much can be learned when using DNA based taxon-specific rates, especially to understand the relative importance and contribution of specific taxa.
More taxon-specific molecular studies will have to be carried out to quantify specific rates of more phytoplankton groups, which will supply a more complete knowledge of phytoplankton community dynamics in the Sargasso Sea. This will increase our understanding of the role of specific groups to the biological carbon dynamics in the euphotic zone into the deep ocean.

Contributors

Agent

Created

Date Created
  • 2013-05

135681-Thumbnail Image.png

The Neurochemical Consequences of Music Therapy on Dementia Patients

Description

As the incidence of dementia continues to rise, the need for an effective and non-invasive method of intervention has become increasingly imperative. Music therapy has exhibited these qualities in addition

As the incidence of dementia continues to rise, the need for an effective and non-invasive method of intervention has become increasingly imperative. Music therapy has exhibited these qualities in addition to relatively low implementation costs, therefore establishing itself as a promising means of therapeutic intervention. In this review, current research was investigated in order to determine its effectiveness and uncover the neurochemical mechanisms that lead to positive manifestations such as improved memory recall, increased social affiliation, increased motivation, and decreased anxiety. Music therapy has been found to improve several aspects of memory recall. One proposed mechanism involves temporal entrainment, during which the melodic structures present in music provide a framework for chunking information. Although entrainment's role in the treatment of motor defects has been thoroughly studied, its role in treating cognitive disorders is still relatively new. Musicians have also been shown to demonstrate extensive plastic changes; therefore, it is hypothesized that non-musicians may also glean some benefits from engaging in music. Social affiliation has been found to increase due to increases in endogenous oxytocin. Oxytocin has also been shown to strengthen hippocampal spike transmission, a promising outcome for Alzheimer's patients. An increase in motivation has also been found to occur due to music's ability to tap into the reward center of the brain. Dopaminergic transmission between the VTA, NAc and higher functioning regions such as the OFC and hypothalamus has been revealed. Additionally, relaxing music decreases stress levels and modifies associated autonomic processes, i.e. heart rate, blood pressure, and respiratory rate. On the contrary, stimulating music has been found to initiate sympathetic nervous system activity. This is thought to occur by either a reflexive brainstem response or stimulus interpretation by the amygdala.

Contributors

Agent

Created

Date Created
  • 2016-05

136342-Thumbnail Image.png

F2-isoprostanes and F2-isoprostane Metabolites: Biomarkers for Oxidative Stress and Therapeutic Efficacy

Description

F2-isoprostanes are a series of prostaglandin-like compounds derived from the free radical-mediated lipid peroxidation of arachidonic acid, a polyunsaturated fatty acid that is ubiquitously expressed in cell membranes. F2-isoprostanes are

F2-isoprostanes are a series of prostaglandin-like compounds derived from the free radical-mediated lipid peroxidation of arachidonic acid, a polyunsaturated fatty acid that is ubiquitously expressed in cell membranes. F2-isoprostanes are biomarkers of oxidative stress, an imbalance between oxidants and antioxidants that can cause damage to DNA, proteins, lipids, and carbohydrates. Increased production of lipid peroxidation products have been implicated in the pathology of a number of conditions and diseases in humans. The objective of this thesis was to (1) optimize the LC/MS/MS F2-isoprostane method currently used in human samples for use in research animals and veterinary medicine, including the use of solid phase extraction, and (2) validate the optimized method in rodent and canine experimental studies. Our optimized method showed that Lyprinol treatment in dogs with osteoarthritis decreases F2-isoprostane levels nearly 2-fold. In addition, adjuvant alpha-tocopherol prevented tumor-induced increased F2-isoprostane levels. Finally, contrary to earlier studies using less specific ELISA F2-isoprostane methods, we demonstrate that unconditioned dogs benefit from low intensity exercise. Our data demonstrate successful optimization of the human LC/MS/MS F2-isoprostane method in rats and canines. Importantly, our results emphasize the need to use the more sensitive and specific LC/MS/MS method as compared to ELISA-based assays in order to distinguish the 15- and 5-series F2-isoprostanes, evidenced in particular by the two canine studies.

Contributors

Agent

Created

Date Created
  • 2015-05

135875-Thumbnail Image.png

Quinone Removal and Replacement within the Reaction Center Protein of Rhodobacter sphaeroides

Description

With a quantum efficiency of nearly 100%, the electron transfer process that occurs within the reaction center protein of the photosynthetic bacteria Rhodobacter (Rh.) sphaeroides is a paragon for understanding

With a quantum efficiency of nearly 100%, the electron transfer process that occurs within the reaction center protein of the photosynthetic bacteria Rhodobacter (Rh.) sphaeroides is a paragon for understanding the complexities, intricacies, and overall systemization of energy conversion and storage in natural systems. To better understand the way in which photons of light are captured, converted into chemically useful forms, and stored for biological use, an investigation into the reaction center protein, specifically into its cascade of cofactors, was undertaken. The purpose of this experimentation was to advance our knowledge and understanding of how differing protein environments and variant cofactors affect the spectroscopic aspects of and electron transfer kinetics within the reaction of Rh. sphaeroides. The native quinone, ubiquinone, was extracted from its pocket within the reaction center protein and replaced by non-native quinones having different reduction/oxidation potentials. It was determined that, of the two non-native quinones tested—1,2-naphthaquinone and 9,10- anthraquinone—the substitution of the anthraquinone (lower redox potential) resulted in an increased rate of recombination from the P+QA- charge-separated state, while the substitution of the napthaquinone (higher redox potential) resulted in a decreased rate of recombination.

Contributors

Agent

Created

Date Created
  • 2015-12

136305-Thumbnail Image.png

Examining the Effect of Vinegar on Glucose Response

Description

The objective of this randomized, single-blind crossover study was to examine the effect of vinegar on the blood glucose response to meal ingestion. This study was associated with a

The objective of this randomized, single-blind crossover study was to examine the effect of vinegar on the blood glucose response to meal ingestion. This study was associated with a companion study Is Apple Cider Vinegar Effective for Reducing Heartburn Symptoms Related to Gastroesophageal Reflux Disease. Glucose meters were utilized to measure blood glucose levels immediately prior to, and at four ½ hour intervals following meal ingestion. Previous studies have demonstrated that vinegar modulates the meal-time glucose response. Hence an alternative hypothesis was used: that a significant difference will be observed between the control and the vinegar groups. The results from the study were not significant likely due to a small sample size. The test meal eaten with a drink composed of vinegar diluted in water appeared to be most effective at decreasing the overall change in postprandial blood glucose. The vinegar drink also played a role in decreasing the peak glucose level at 30 minutes post-meal.

Contributors

Agent

Created

Date Created
  • 2015-05

136243-Thumbnail Image.png

ELECTRON TRANSFER PROCESS BETWEEN COFACTORS OF HELIOBACTERIA'S REACTION CENTER

Description

ABSTRACT:
The experiment was conducted to analyze the role of menaquinone (MQ) in heliobacteria’s reaction center (HbRC). Their photosynthetic apparatus is a homodimeric of type I reaction center (1). HbRC

ABSTRACT:
The experiment was conducted to analyze the role of menaquinone (MQ) in heliobacteria’s reaction center (HbRC). Their photosynthetic apparatus is a homodimeric of type I reaction center (1). HbRC contains these cofactors: P800 (special pair cholorphyll), A0 (8-hydroxy-chlorophyll [Chl] a), and FX (iron-sulfur cluster). The MQ factor is bypassed during the electron transfer process in HbRC. Electrons from the excited state of P800 (P800*) are transported to A0 and then directly to Fx. The hypothesis is that when electrons are photoaccumulated at Fx, and without the presence of any electron acceptors to the cluster, they would be transferred to MQ, and reduce it to MQH2 (quinol). Experiments conducted in the past with HbRC within the cell membranes yielded data that supported this hypothesis (Figures 4 and 5). We conducted a new experiment based on that foundation with HbRC, isolated from cell membrane. Two protein assays were prepared with cyt c553 and ascorbate in order to observe this phenomenon. The two samples were left in the glove box for several days for equilibration and then exposed to light in different intensity and periods. Their absorption was monitored at 800 nm for P800 or 554 nm for cyt c553 to observe their oxidation and reduction processes. The measurements were performed with the JTS-10 spectrophotometer. The data obtained from these experiments support the theory that P800+ reduced by the charge recombination of P800+Fx-. However, it did not confirm the reduction of P800+ done by cyt c553¬ which eventually lead to a net accumulation of oxidized cyt c553; instead it revealed another factor that could reduce P800+ faster and more efficient than cyt c553 (0.5 seconds vs several seconds), which could be MQ. More experiments need to be done in order to confirm this result. Hence, the data collected from this experiment have yet to support the theory of MQ being reduced to MQH2 outside the bacterial membranes.

Contributors

Agent

Created

Date Created
  • 2015-05

136336-Thumbnail Image.png

The Optimization of Conditions for Maximum Hydrogen Production in Heliobacterium modesticaldum

Description

Hydrogen has the potential to be a highly efficient fuel source. Its current production via steam reformation of natural gas, however, consumes a large amount of energy and gives off

Hydrogen has the potential to be a highly efficient fuel source. Its current production via steam reformation of natural gas, however, consumes a large amount of energy and gives off carbon dioxide. A newer method has since surfaced: using a microorganism's metabolism to drive hydrogen production. In this study, the conditions for maximum hydrogen production in Heliobacterium modesticaldum were identified and assessed. The cells were grown under varying conditions and their headspaces were sampled using a gas chromatogram to measure the amount of accumulated hydrogen during each condition. Two cell batches were grown under nitrogen-fixing conditions (-NH4+), while the other two cell batches were grown under non-nitrogen-fixing conditions (+NH4+). The headspaces were then exchanged with either nitrogen (N2) or argon (Ar2). It was found that the condition for which the most hydrogen was produced was when the cells were grown under nitrogen-fixing conditions and the headspace was exchanged with argon. These results suggest that most of Heliobacteria modesticaldum's hydrogen production is due to nitrogenase activity rather than hydrogenase activity. Further research is recommended to quantify the roles of nitrogenase, [NiFe] hydrogenase, and [FeFe] hydrogenase.

Contributors

Agent

Created

Date Created
  • 2015-05