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You searched for subject:(Yeast bioassay). Showing records 1 – 3 of 3 total matches.

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1. Richter, Ingrid. Molecular evolution and functional characterisation of tunicate xenobiotic receptors.

Degree: 2015, Victoria University of Wellington

Marine microorganisms generate a wide range of ’bioactive’ compounds that can have far-reaching effects on biological and ecological processes. Metazoans have developed specialised biochemical pathways that metabolise and eliminate potentially toxic chemicals (xenobiotics) from their bodies. The vertebrate xenobiotic receptor, pregnane X receptor (PXR), is a ligand-activated nuclear receptor transcription factor regulating expression of multiple detoxification genes. Ligand-binding domains (LBDs) of vertebrate PXR orthologues may have adaptively evolved to bind toxins typically encountered by these organisms. Marine invertebrate filter-feeders are exposed to relatively high concentrations of xenobiotics associated with their diet. Tunicates (phylum: Chordata) are of particular interest as they form the sister clade to the Vertebrata. Genomes of the solitary tunicate Ciona intestinalis and the colonial tunicate Botryllus schlosseri both encode at least two xenobiotic receptors that are orthologues to both the vertebrate vitamin D receptor (VDR) and PXR. Pursuing the idea that tunicate xenobiotic receptors (VDR/PXR) may adaptively evolve to bind toxic chemicals commonly present in an organism’s environment, this thesis aims to identify if: (i) adaptive evolution is acting on putative tunicate VDR/PXR orthologues to enhance binding of dietary xenobiotics; (ii) these receptors are activated by dietary xenobiotics (e.g. microalgal biotoxins) and; (iii) tunicate VDR/PXR LBDs can be used as sensor elements in yeast bioassays for the detection of both natural and synthetic bioactive compounds. To identify genetic variation and to search for evidence of positive selection, next-generation sequencing was performed on three tunicate VDR/PXR orthologues genes. Recombinant yeast (Saccharomyces cerevisiae) cell lines were developed for the functional characterisation of tunicate VDR/PXR LBDs. These tunicate VDR/PXR LBD-based yeast bioassays were utilised to detect known microalgal biotoxins, natural bioactive compounds, and environmental contaminants. Next-generation sequencing revealed both an unusually high genetic diversity and strong purifying selection in VDR/PXR orthologues from C. intestinalis and B. schlosseri. Single-base-deletion allelic variants were found in C. intestinalis VDR/PXR orthologues resulting in predicted proteins having a DNA-binding domain but lacking a LBD. The persistence of these variants may reflect constitutive expression of detoxification genes as a selective advantage in the marine environment. To assess the functional characteristics of tunicate VDR/PXR orthologues, recombinant yeast cell lines were developed that express VDR/PXRα LBDs from C. intestinalis and B. schlosseri. These chimeric proteins mediate liganddependent expression of a lacZ reporter gene which encodes an easily assayed enzyme (β-galactosidase). These yeast bioassays were highly sensitive towards both synthetic and natural toxins (coefficients of variance, CV <25%). Microalgal biotoxins (okadaic acid and portimine) were two… Advisors/Committee Members: McNatty, Ken, Fidler, Andrew.

Subjects/Keywords: Yeast bioassay; PXR; Pregnane X receptor; Molecular evolution

…using bioassays based on functional expression of tunicate xenobiotic receptors in yeast… …Novel yeast bioassays based on tunicate xenobiotic receptors for high-throughput screening of… …Simplified schematic of modified yeast one-hybrid 37 bioassays. Figure 2.1 Genetic diversity… …Figure 3.3 Example of a 96-well plate format used in the tunicate 98 yeast bioassays. Figure… …recombinant yeast strains. Figure 3.5 Influence of L-histidine concentrations on background 106… 

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APA (6th Edition):

Richter, I. (2015). Molecular evolution and functional characterisation of tunicate xenobiotic receptors. (Doctoral Dissertation). Victoria University of Wellington. Retrieved from http://hdl.handle.net/10063/4652

Chicago Manual of Style (16th Edition):

Richter, Ingrid. “Molecular evolution and functional characterisation of tunicate xenobiotic receptors.” 2015. Doctoral Dissertation, Victoria University of Wellington. Accessed January 18, 2021. http://hdl.handle.net/10063/4652.

MLA Handbook (7th Edition):

Richter, Ingrid. “Molecular evolution and functional characterisation of tunicate xenobiotic receptors.” 2015. Web. 18 Jan 2021.

Vancouver:

Richter I. Molecular evolution and functional characterisation of tunicate xenobiotic receptors. [Internet] [Doctoral dissertation]. Victoria University of Wellington; 2015. [cited 2021 Jan 18]. Available from: http://hdl.handle.net/10063/4652.

Council of Science Editors:

Richter I. Molecular evolution and functional characterisation of tunicate xenobiotic receptors. [Doctoral Dissertation]. Victoria University of Wellington; 2015. Available from: http://hdl.handle.net/10063/4652


AUT University

2. Gurazada, Saroja. Use of yeast species as the biocomponent for priority environmental contaminants biosensor devices .

Degree: 2008, AUT University

Along with an increasing understanding of the harmful effects on the environment of a wide range of pollutants has come the need for more sensitive, faster and less expensive detection methods of identification and quantitation. Many environmental pollutants occur in low levels and often in complex matrices thus analysis can be difficult, time consuming and costly. Because of the availability and easy cultivation of the microorganisms with potentially high specificity, there is considerable interest in the use of living microorganisms as the analytical component (the biocomponent) of sensors for pollutants. While a number of biosensors using bacteria have been developed, yeast has been comparatively rarely used as the biocomponent. Yeast are attractive because they are easy to culture and they are eukaryotes which means their biochemistry is in many respects closer to that of higher organisms. This thesis describes the development of whole cell bioassays that use yeast cells as a sensing element and redox mediators to probe the intracellular redox reactions to monitor the catabolic activity of the yeast resulting from the external substrate, steady-state voltammetry is utilised as the electrochemical detection technique. The isogenic differential enzyme analysis (IDEA) concept of Lincoln Ventures Limited, lead NERF funded research consortium uses bacteria that have been cultured using specific organic pollutants as the carbon source which are the biocomponent in sensors. The use of wild type yeast Arxula adeninivorans that has the ability to use a very wide variety of substrates as sources of carbon and nitrogen was used as an alternative to bacteria to validate the “IDEA” concept. Naphthalene and di-butyl phthalate were chosen as model target contaminant molecules. The performance, detection limits and the usefulness of yeast based biosensor applications for environmental analysis are discussed. This thesis also describes the development and optimisation of a simple, cost effective in vivo estrogens bioassay for the detection of estrogens using either genetically modified or a wild type yeast Saccharomyces cerevisiae. In this study, catabolic repression by glucose was exploited to achieve specificity to estrogens in complex environmental samples that eliminates the requirement for conventional sample preparation. This is the first time that the use of wild type yeast to quantify estrogens has been reported. The attractive features of the bioassay are its use of a non-GMO organism, its speed, its high specificity and sensitivity with a detection limit of 10-15 M. The similarity of binding affinities for major estrogens to those of human estrogens receptors makes this in vivo estrogen bioassay very useful for analytical/screening procedures. The electrochemical detection method also makes it easy to interface with a variety of electronic devices. Advisors/Committee Members: Robertson, John (advisor).

Subjects/Keywords: Yeast; Biosensors; Environmental contaminants; Estrogen bioassay; Electrochemical deduction; Redox mediators

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APA (6th Edition):

Gurazada, S. (2008). Use of yeast species as the biocomponent for priority environmental contaminants biosensor devices . (Thesis). AUT University. Retrieved from http://hdl.handle.net/10292/430

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Gurazada, Saroja. “Use of yeast species as the biocomponent for priority environmental contaminants biosensor devices .” 2008. Thesis, AUT University. Accessed January 18, 2021. http://hdl.handle.net/10292/430.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Gurazada, Saroja. “Use of yeast species as the biocomponent for priority environmental contaminants biosensor devices .” 2008. Web. 18 Jan 2021.

Vancouver:

Gurazada S. Use of yeast species as the biocomponent for priority environmental contaminants biosensor devices . [Internet] [Thesis]. AUT University; 2008. [cited 2021 Jan 18]. Available from: http://hdl.handle.net/10292/430.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Gurazada S. Use of yeast species as the biocomponent for priority environmental contaminants biosensor devices . [Thesis]. AUT University; 2008. Available from: http://hdl.handle.net/10292/430

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


University of Florida

3. Graham, Jason. The Attraction of Bumble Bee (bombus Impatiens Cresson; Hymenoptera Apidae) Colonies to the Small Hive Beetle (aethina Tumida Murray; Coleoptera: Nitidulidae).

Degree: MS, Entomology and Nematology, 2009, University of Florida

The small hive beetle (Aethina tumida Murray, Coleoptera: Nitidulidae; SHB) a pest of the Western honey bee (Apis mellifera L.; Hymenoptera: Apidae) has been found in commercial bumble bee (Bombus impatiens Cresson, Hymenoptera: Apidae) colonies. A genus level host shift may be devastating to commercial and wild bumble bee colonies, a significant problem due to the value of bumble bees as pollinators. Further, bumble bee colonies may serve as an unmonitored source of SHB reproduction. For these reasons, understanding what mediates the attraction of SHBs to bumble bee colonies is important. Previously, investigators discovered a multitrophic interaction in which Kodamaea ohmeri (Ascomycota: Saccharomycetaceae), yeast transmitted by SHBs, played an important role in host location. Presumably, SHB deposit K. ohmeri onto pollen while they feed. When exposed to pollen, K. ohmeri produces components of honey bee alarm pheromone found to attract SHBs. To better understand SHB attraction to bumble bee colonies, three studies were conducted to investigate bumble bee/SHB interactions. In the first study (Chapter 2), SHB attraction to components present in honey bee and bumble bee colonies was investigated under the hypothesis that SHB are as attracted to bumble bee produced volatiles as they are to honey bee produced volatiles. The bumble bee vs. control bioassay results suggest that SHB are attracted to bumble bee adults, stored pollen, brood, wax, and the whole bumble bee hive though not to honey. SHB did not show a preference for honey bee or bumble bee components in the honey bee vs. bumble bee assays. Collectively, the data suggest that SHBs are as attracted to bumble bee colonies as they are to honey bee colonies and this attraction is chemically mediated. In the second study (Chapter 3), airborne volatiles were collected from commercial bumble bee and honey bee colonies and from each component of both colony types (adult bees, brood, honey, pollen and wax) to determine the chemical profile of volatiles present. In general, the volatile profiles of bumble bee and honey bee colonies were dissimilar with only 7 of 148 total compounds detected common to both colonies. In the final study (Chapter 4), eight commercial bumble bee colonies were tested for the presence of K. ohmeri which was present on all of the colony swab samples (n = 7 colonies times 8 swabs/colony = 56 samples). Furthermore, yeast was found in 6 of 7 adult bee samples, 2 of 5 pollen samples, 4 of 8 wax samples but not in brood or honey samples (each sample was from a different colony). This demonstrates that bumble bee nests are suitable micro-environments for the growth of K. ohmeri. Collectively, these findings support the overall hypothesis that attraction of SHBs to bumble bee colonies is chemically mediated. The success of the SHB at expanding its host range may be due to both types of bee colonies harboring K. ohmeri. Every effort should be made to determine the susceptibility of wild bee colonies to SHBs and the role K. ohmeri plays in SHB… Advisors/Committee Members: Ellis, James D. (committee chair), Boucias, Drion G. (committee member), Teal, Peter E. (committee member).

Subjects/Keywords: Bees; Beetles; Bioassay; Honey; Honey bee colonies; Honey bees; Parasite hosts; Pollen; Waxes; Yeasts; aethina, apis, bee, beetle, bombus, bumble, choice, hive, honey, impatiens, kodamaea, mellifera, ohmeri, parasite, small, social, symbiosis, tumida, yeast; City of Gainesville ( local )

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Graham, J. (2009). The Attraction of Bumble Bee (bombus Impatiens Cresson; Hymenoptera Apidae) Colonies to the Small Hive Beetle (aethina Tumida Murray; Coleoptera: Nitidulidae). (Masters Thesis). University of Florida. Retrieved from https://ufdc.ufl.edu/UFE0024736

Chicago Manual of Style (16th Edition):

Graham, Jason. “The Attraction of Bumble Bee (bombus Impatiens Cresson; Hymenoptera Apidae) Colonies to the Small Hive Beetle (aethina Tumida Murray; Coleoptera: Nitidulidae).” 2009. Masters Thesis, University of Florida. Accessed January 18, 2021. https://ufdc.ufl.edu/UFE0024736.

MLA Handbook (7th Edition):

Graham, Jason. “The Attraction of Bumble Bee (bombus Impatiens Cresson; Hymenoptera Apidae) Colonies to the Small Hive Beetle (aethina Tumida Murray; Coleoptera: Nitidulidae).” 2009. Web. 18 Jan 2021.

Vancouver:

Graham J. The Attraction of Bumble Bee (bombus Impatiens Cresson; Hymenoptera Apidae) Colonies to the Small Hive Beetle (aethina Tumida Murray; Coleoptera: Nitidulidae). [Internet] [Masters thesis]. University of Florida; 2009. [cited 2021 Jan 18]. Available from: https://ufdc.ufl.edu/UFE0024736.

Council of Science Editors:

Graham J. The Attraction of Bumble Bee (bombus Impatiens Cresson; Hymenoptera Apidae) Colonies to the Small Hive Beetle (aethina Tumida Murray; Coleoptera: Nitidulidae). [Masters Thesis]. University of Florida; 2009. Available from: https://ufdc.ufl.edu/UFE0024736

.