Thèses : « Chemosensori »

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PIERSANTI, LUCA. « Nuovi chemosensori ottici aventi un derivato benzossazolico come unità sensibile ». Doctoral thesis, Urbino, 2015. http://hdl.handle.net/11576/2628889.

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Samuelsen, Chad L. « Chemosensory processing in the amygdala ». Tallahassee, Florida : Florida State University, 2009. http://etd.lib.fsu.edu/theses/available/etd-09212009-161414/.

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Thesis (Ph. D.)--Florida State University, 2009.
Advisor: Michael Meredith, Florida State University, College of Arts and Sciences, Dept. of Biological Science. Title and description from dissertation home page (viewed on May 4, 2010). Document formatted into pages; contains xv, 131 pages. Includes bibliographical references.

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Olofsson, Jonas. « Gender differences in chemosensory function ». Licentiate thesis, Umeå University, Department of Psychology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-22533.

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This thesis consists of two studies, in which gender differences in nasal chemosensory function are investigated. The first study assesses odor identification ability in a populationbased sample, varying from 45 to 90 yrs, screened for cognitive impairment and severe olfactory dysfunction. Results show that women are generally better than men at identifying odors, but there is no significant interaction of gender by age. Although odoridentification is influenced by semantic memory and cognitive speed, these cognitivefactors are unlikely to cause the observed gender difference in odor identification. The second study investigates chemosensory perception in men and women by assessing eventrelatedbrain potentials, and perceptual ratings for an odorant, which varies inconcentration and olfactory/irritating properties. The results display a generally larger cortical response in women than in men, beginning from about 350 ms after stimulus onset. Women report higher perceived intensity and npleasantness at the highest stimulus concentration, and a steeper psychophysical function, than do men. The results indicatethat stronger cortical responses of nasal chemosensory stimuli provide a neural basis for stronger supra-threshold perception in women than in men, which might enhance odor identification performance. The nature and causes of these gender-differences in nasal chemosensory function are discussed.

This thesis for the licenciate degree is based on the following studies:Larsson, M., Nilsson, L-G., Olofsson, J.K., & Nordin, S. (2004). Demographic and cognitive predictors of odor identification: Evidence from a population-based study.Chemical Senses, 29, 547-554.Olofsson, J.K., & Nordin, S. (2004). Gender differences in chemosensory perception andevent-related potentials. Chemical Senses, 29, 629-637.

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Roberts, Craig Dane. « cAMP Signaling in Chemosensory Transduction ». Scholarly Repository, 2008. http://scholarlyrepository.miami.edu/oa_dissertations/161.

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cAMP is a second messenger in a variety of chemosensory receptors, including taste buds and glucose-sensitive pancreatic beta-cells. cAMP is modulated during taste transduction, yet the significance of cAMP changes and the taste cell types in which they occur (Type I glial-like; Type II Receptor; Type III Presynaptic) remain unclear. I developed techniques to image real-time changes in intracellular cAMP in taste cells using genetically-encoded cAMP reporters. This FRET-based reporter permits one to measure single-cell cAMP levels with excellent spatial and temporal resolution (Zaccolo & Pozzan 2002, Science 295:1711). Using a biolistic approach I have transfected rat fungiform taste buds with cAMP reporter plasmids. Focal application of bitter tastant to living fungiform tastebuds in situ produced a decrease in [cAMP]i within individual taste receptor cells. These results are qualitatively similar to previous biochemical measurements from homogenized taste tissue (Yan et al. 2001, Am J Physiol Cell Physiol 280:C742) but are now allowing us to examine the cAMP response in individual, identified cells. I next explored the effect of elevating cAMP on calcium levels, using Fura-2 imaging of isolated mouse vallate taste buds. Elevating [cAMP]i in taste buds evoked calcium responses in presynaptic/Type III taste cells, which do not express GAD1. cAMP induced responses were generated by calcium influx. Using pharmacological antagonists, I determined that the calcium influx triggered by cAMP is through L-type calcium channels, whereas influx following depolarization is primarily through P/Q-type calcium channels. Consistent with these data, single cell RT-PCR showed that the L-type subunit (alpha 1C) was expressed primarily in GAD-negative Presynaptic cells, while the P/Q-type (alpha 1A) was expressed in all Presynaptic cells. Thus, cAMP may modulate the function of synapses in some taste cells. Finally, we have developed a mouse strain expressing a cAMP reporter in a tissue-specific and tetracycline-inducible manner. We crossed this mouse with another strain expressing tet-activator in beta cells of the pancreas. Such islets responded to increasing concentrations of glucose (5.5 to 35mM) with an increase in cAMP levels. The half maximum of 9mM glucose for the cAMP response corresponds well with reported glucose concentrations that elicit insulin release from whole islets. Stimulating pancreatic islets with glucose is known to drive calcium influx into beta-cells. When we simultaneously imaged both second messengers, we found that cAMP changes precede and are independent of calcium changes. In conclusion, these studies have outlined novel potential functions for cAMP signaling in the transduction of both primary tastant and plasma glucose information. In addition, the flexibility of the tet-system will enable cAMP reporter expression in numerous cell types, including those which mediate gustatory transduction.

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Stephens, Bonnie Baggett. « Chemosensory Responses in Azospirillum brasilense ». Digital Archive @ GSU, 2006. http://digitalarchive.gsu.edu/biology_diss/11.

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The ability to swim and navigate the surrounding environment confers an advantage to motile bacteria, allowing the occupation of niches that are optimum for survival and growth. Bacteria are too small to sense their environment spatially, so they must sense the environment temporally by comparing the past and present environments and altering their motility accordingly. Chemotaxis systems coordinate flagellar motility responses with temporal sensing of the environment. Chemotaxis is proposed to be involved in plant root colonization by directing soil bacteria toward root exudates of various cereals, promoting growth. The nitrogen-fixing alpha-proteobacterium Azospirillum brasilense utilizes chemotaxis to navigate its environment by integrating various environmental signals into a chemotaxis signal transduction pathway. In chemotaxis, transducers receive environmental sensory information and transmit the signal to the histidine kinase CheA, which relays the signal to the response regulator CheY. A novel chemotaxis transducer, Tlp1, has been identified and characterized as an energy sensor by constructing a tlp1 mutant and performing behavioral and root colonization assays. In order to adapt to changing environmental conditions, chemotactic microorganisms must employ a molecular “memory” comparing present environmental conditions to ones previously experienced and resetting the chemotaxis transducer to a prestimulatory status. A recently identified chemotaxis operon revealed a methyltransferase CheR and methylesterase CheB, comprising an adaptation system, suggesting that A. brasilense undergoes methylation-dependent taxis responses, contrary to previous reports. Chemotaxis and methanol release assays suggest that adaptation by methylation in locomotor behavior involves the presence of other unknown methylation systems, and the contribution of CheR and CheB to chemotactic and aerotactic responses is complex. There is growing evidence that chemotaxis-like signal transduction pathways control a myriad of other cellular processes regulated in a temporal fashion. This would convey an advantage to cells by allowing modulation of cellular processes based on slight changes in environmental conditions and provide checkpoints for energetically consuming processes. Mutations in components of the chemotaxis-like signal transduction system revealed differences in cell size and exopolysaccharide production. This work shows that the signal transduction pathway of A. brasilense modulates cell length in response to changes in nutrient conditions, independently of growth rate.

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Dujols, Virginie Elisabeth. « Rhodamine & ; anthracene-based chemosensors / ». The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487941504294111.

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Cabell, Larry Allen. « Chemosensors and competition sensing assays / ». Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.

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Fang, Albert Geeson. « Development of novel fluorescent chemosensors / ». Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2004. http://wwwlib.umi.com/cr/ucsd/fullcit?p3138822.

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Jin, Shan. « Development of Boronic Acid-Based Chemosensors ». Digital Archive @ GSU, 2009. http://digitalarchive.gsu.edu/chemistry_diss/31.

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It is well known that boronic acids can bind with diols and can be further applied as chemosensors for biomolecules such as carbohydrates and dopamine. Carbohydrates are known to mediate a large number of biological and pathological events. Small and macromolecules capable of carbohydrate recognition have great potentials as research tools, diagnostics, vectors for targeted delivery of therapeutic and imaging agents, and therapeutic agents.

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Lau, Hsien Lee. « Chemosensory context conditioning in Caenorhabditis elegans ». Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/25779.

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These studies were designed to investigate how environmental cues are associated during a non-associative learning process by studying chemosensory context conditioning for habituation in the nematode Caenorhabditis elegans. In chemosensory context conditioning for habituation animals that are trained and tested in the presence of either a taste or smell context cue show greater retention of habituation to tap stimuli when compared to animals trained and tested in different environments. This thesis is based on the work of Rankin (2000), in which taste (sodium acetate) context conditioning of habituation, extinction and latent inhibition of the cue were demonstrated. Here, I have shown context conditioning for an olfactory chemosensory cue (diacetyl) and dissociated the taste and smell pathways for this form of learning. odr-7 worms, with non-functional AWA olfactory chemosensory neuron (that detects diacetyl), showed short-term context conditioning to the taste but not to smell; the reverse was true for osm-3 worms with non-functional taste chemosensory neurons. This dissociation allows me to distinguish learning genes from genes involved in the detection of taste or smell. I also demonstrated long-term associative memory (24h) for context conditioning; context conditioning did not enhance normal long-term habituation, however, it produced memory in a training procedure that normally does not produce memory. My results showed that glr-1 (an AMPA-type ionotropic glutamate receptor subunit) and nmr-1 (an NMDA-type ionotropic glutamate receptor subunit) mutant worms did not show either short- or long-term context conditioning. To identify one site of plasticity, I showed that NMR-1 in the RIM interneurons was critical to produce short-term olfactory context conditioning. These studies lay the foundation to elucidate the cellular mechanisms of non-associative and associative learning for both short- and long-term memory, and may provide insights into how interneurons integrate information from multiple sensory systems.

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Martinez, Rebecca L. « Chemosensory Evaluation of Prostate Cancer Cells ». Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/46316.

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Prostate cancer is the most commonly diagnosed disease and second most commonly caused death among men in America. Although much controversy surrounds the current methods of detection, PSA test and biopsy, no new methods have been approved as an effective method of detection. Biomarkers and non-invasive means of detection are being investigated everyday in hopes of discovering new information that could be of use in the prostate cancer field. One such non-invasive technology is the use of an electronic nose. The electronic nose technology has been utilized in the agricultural, food, biomedical, and environmental. The objective of this current study is to determine the effectiveness of the electronic nose to discriminate between prostate cancer cells (DU-145 and PC-3) and non-tumor forming cells from the urinary tract (SVHUC). Specific factors that will be investigated are incubation period and cell population. For all three cell lines, two cell populations of 75,000 and 150,000 cells were cultured and tested after 2, 8, 12, and 24 hours using a conducting polymer based hand-held electronic nose. Multivariate analysis was performed on the data and determined that the greatest discrimination between incubation periods was between 2 hours of incubation and the remaining periods of 8, 12, and 24 hour periods. This presents the idea that by 8 hours, ample volatiles were produced to be detected by the electronic nose. Additionally, when compared to one another, all three cell lines showed distinct differences. The cell lines most closely related were PC-3 and DU-145, the prostate cancer cell lines. However some variation was seen between these cell lines, which may be attributed to the presence of PSA in PC-3 cells or other factors affecting prostate cancer patients. Finally, PCA plots clearly illustrated that after 2 hours of incubation, sufficient volatiles were produced to allow the electronic nose to clearly discriminate the three cell lines from one another, demonstrating the importance of incubation period on successful discrimination. Based on the findings that the electronic nose was effective at discriminating the three cell lines, testing was completed to determine if cell population or cell maturity had the greatest effect on discrimination. The cell lines were cultured and tested immediately using an initial cell population of the highest cell population observed after a 72 hour incubation period. The results concluded that when the cell lines were tested immediately after culturing, the Cyranose was able to detect the individual cell lines in culture while also determining a range of detection for each cell line. The range of detection for DU-145 was found to be 26,200 to 262,000 cells based on interclass m-distances of 6.829-9.170 for cell populations lower than 26,200. A range of detection of 51,400 to 514,000 cells was concluded for PC-3 cells based on interclass m-distances of 5.690-7.400 for cell populations lower than 51,400. Finally, the results showed a range of detection of 19,000 to 190,000 cells for SVHUC based on interclass m-distances of 5.520-9.076 for cell populations lower than 19,000. However, when attempting to discriminate the three cell lines against one another immediately after culture, the electronic nose was unable to make clear distinctions between the three cell lines. When testing cancerous and non-cancerous cells, incubation period of the cells should be the only factor considered. It is evident that the cells need time to metabolize and produce volatiles so that the electronic nose can clearly distinguish these cells from one another in culture.
Master of Science

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Mantotta, Jeevani Charika. « Analysis of chemosensory proteins in Rhodobacter sphaeroides ». Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249546.

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Rogers, Stephen M. « Chemosensory development and integration in Locusta migratoria ». Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298420.

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Santos, Carla Isabel Madeira dos. « Corroles : synthesis, functionalization and application as chemosensors ». Doctoral thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/11959.

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Departamento em Química
O trabalho de investigação apresentado nesta dissertação foi desenvolvido tendo como objectivo a síntese e funcionalização de meso-triarilcorróis para utilização como quimiossensores. Este trabalho encontra-se apresentado ao longo de cinco capítulos. No primeiro capítulo são apresentadas as características gerais, as metodologias de síntese e de funcionalização de macrociclos de tipo corrólico, e descrevemse algumas aplicações em que têm sido utilizados. São ainda abordadas algumas das propriedades e características dos quimiossensores e os mecanismos de deteção de diversos analítos. No segundo capítulo, após uma pequena introdução às reações de Wittig e de Diels-Alder, escolhidas para a funcionalização do macrociclo corrólico, descreve-se o estudo efectuado para a obtenção do complexo de gálio(III) do 3- vinil-5,10,15-tris(pentafluorofenil)corrol e o seu comportamento como dieno, em reações de Diels-Alder na presença dos dienófilos 1,4-benzoquinona e 1,4- naftoquinona. Desses estudos resultaram dois aductos cuja habilidade sensorial, bem como a dos seus precursores, foi estudada, em solução, na presença de aniões esféricos (F-, Br-, Cl-), lineares (CN-) e volumosos (CH3COO-, H2PO4 -). Dos macrociclos estudados verificou-se que o corrol base-livre 5,10,15-tris(pentafluorofenil)corrol apresenta uma elevada sensibilidade para o anião fluoreto (F-), e que a coordenação do núcleo corrólico com gálio(III) diminui a afinidade para este anião. Em geral, todos os compostos mostraram afinidade para o anião cianeto (CN-) mesmo quando em suportes poliméricos. O gel de poliacrilamida revelou-se muito promissor na determinação de CN- em amostras de água. No terceiro capítulo é avaliada a reatividade do complexo de gálio(III) do 3- vinil-5,10,15-tris(pentafluorofenil)corrol ainda como dieno mas agora na presença de um dienófilo linear, o acetilenodicarboxilato de dimetilo. Desse estudo resultaram dois novos derivados corrólicos. A habilidade sensorial dos mesmos perante os aniões fluoreto, cianeto, acetato, e fosfato foi avaliada por espectroscopia de absorção e emissão tendo um dos aductos mostrado ser colorimétrico para o anião cianeto. No quarto capítulo descreve-se a síntese e caracterização de dois conjugados do tipo corrol-cumarina, resultantes de reações de Hetero-Diels-Alder entre o 3-vinil-5,10,15-tris(pentafluorofenil)corrolatogálio(III)(piridina) e orto-quinonasmetídeos gerados in situ a partir de reacções de Knoevenagel entre cumarinas e paraformaldeído. Realizaram-se estudos de afinidade sensorial para aniões e catiões com estes macrociclos, bem como com conjugados porfirinacumarina análogos. A inserção de uma unidade cumarina conferiu uma excepcional solubilidade tendo os novos derivados apresentado solubilidade em etanol. No quinto e último capítulo desta dissertação é avaliada a capacidade sensorial do 5,10,15-tris(pentafluorofenil)corrol e da sua espécie monoaniónica, para os catiões metálicos Na+, Ca2+, Cu2+, Cd2+, Pb2+, Hg2+, Ag+, Al3+, Zn2+, Ni2+, Cr3+, Ga3+, Fe3+ em tolueno e acetonitrilo. Os macrociclos corrólicos mostraram ser selectivos e colorimétricos para o catião Hg2+. Neste trabalho descreve-se ainda a síntese do derivado -iminocorrol, que após funcionalização com o 3-isocianatopropiltrimetoxisilano originou um derivado do tipo alcoxisilano, que foi, posteriormente, ancorado a nanopartículas comerciais de sílica. As novas nanopartículas ancoradas com o alcoxisilano corrol foram estudadas na presença de Cu2+, Hg2+ e Ag+. Na presença do catião Ag+ assistiu-se a uma mudança de cor, de verde para amarelo.
The work described in this dissertation was focused on the synthesis of mesotriarylcorroles and their functionalization for later use as chemosensors. This work is divided in five chapters. In the first chapter it is described the general features of corroles, synthetic methodologies, the functionalization procedures and the applications of this kind of macrocycles. Additionally, some considerations about chemosensors and the importance of analytes that will be evaluated is also discussed. In the second chapter the Wittig and Diels- Alder reactions were chosen as post-functionalization procedures to apply to corroles. In this way, by the use of a Wittig reaction, the derivative 3–vinil-5,10,15- tris(pentafluorophenyl)corrolatogallium(III) was synthetized, from the corresponding 3-formy-5,10,15-tris(pentafluorophenyl)corrolatogallium(III), and its behavior as diene in Diels–Alder reactions, in the presence of the dienophiles 1,4-benzoquinone and 1,4-naphthoquinone was evaluated. These studies afforded two Diels-Alder adducts whose sensorial ability, as well as of their precursors, was studied in solution in the presence of spherical( F -, Br -, Cl -), linear (CN-) and bulky (CH3COO-, H2PO4 -) anions. The 5,10,15- tris(pentafluorophenyl)corrole showed to be the most sensitive macrocycle to the fluoride anion (F-). Although all derivatives have interacted with this anion the coordination of the corrole core with gallium(III) decreased their affinity for this anion. In general, all compounds showed interaction with cyanide (CN-) anions. By these results two low cost polymers based on polymethylmethacrylate and polyacrylamide were prepared and used in the detection of CN- in water. The polyacrylamide gel proved to be very promising. In the third chapter the reactivity of the gallium(III) (pyridine) complex of 3-vinyl- 5,10,15-tris(pentafluorophenyl)corrole as a diene was extended to dimethyl acetylenedicarboxylate as dienophile. This study afforded two new corrole derivatives. The sensorial ability of the new macrocycles towards fluoride, cyanide, acetate and phosphate anions was carried out by absorption and emission spectroscopy. One of the derivatives showed to be colorimetric to cyanide, where a change of colour from green to colourless was visualized. In the fourth chapter is described the synthesis and characterization of two new derivatives resulting from hetero-Diels-Alder reactions between the gallium(III) (pyridine) complex of 3-vinyl-5,10,15-tris(pentafluorophenyl)corrole and oquinone methides (o-QM) generated in situ from Knoevenagel reactions of coumarins with paraformaldehyde. The sensing ability of the resulting compounds was studied in the presence of different anions and cations. These sensorial studies were extended to porphyrin-coumarin analogues. The insertion of a coumarin moiety conferred an unusual solubility to these conjugates in ethanol. In the last chapter is shown the sensorial ability of 5,10,15- tris(pentafluorophenyl)corrole and of its monoanionic species towards Na+, Ca2+, Cu2+, Cd2+, Pb2+, Hg2+, Ag+, Al3+, Zn2+, Ni2+, Cr3+, Ga3+, Fe3+ metal ions in toluene and acetonitrile. The photophysical studies towards metal ions were carried out by absorption and emission spectroscopy. These corroles showed to be selective and colorimetric for Hg2+. In addition a new - imine corrole was successful synthetized and further functionalized with 3-isocyanatopropyltrimethoxysilane resulting an alkoxysilane derivative. The grafting of alkoxysilane derivative, with optically transparent silica nanoparticles (SiNPs) was also performed. The new-coated silica nanoparticles with corrole were studied in the presence of Cu2+, Hg2+ and Ag+ as metal ion probes. In the presence of Ag+ was observed a change of colour from green to yellow.

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Cheung, Sin Man. « Development of optical chemosensors for cation sensing ». HKBU Institutional Repository, 2007. http://repository.hkbu.edu.hk/etd_ra/771.

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Rosa-Gastaldo, Daniele. « Supramolecular chemosensors for the detection of phenethylamines ». Doctoral thesis, Università degli studi di Padova, 2019. http://hdl.handle.net/11577/3425410.

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In this work I described and discussed the results of a research project which focused on both development and application of the NMR-chemosensing technique. This technique is based on the combination of gold nanoparticles 2 nm in diameter coated with specific thiols and particular NMR experiments, and it allows to “extract” from the NMR spectrum of a mixture of substances the single NMR spectrum of the analyte bound by the nanoparticle. Specifically, the main goal of my work was to demonstrate how this technique can be successfully used for designer-drug detection. The majority of the new drugs that appear on the market every year belong to this category, i.e. they are structural analogs of already well-known drugs. Designer drugs represent a big health issue, because no studies on them are available, therefore the risks and potential long-term adverse effects are not known. Moreover, as reference standards are not available, their sensing with routine techniques is difficult. The technique that I will describe also works on real street samples, with no pretreatment, thus giving the possibility to get from the seizure of the powder to the characterization of the substance in a few hours. I’ll also show that to improve the potentialities of NMR chemosensing in terms of detection limit and sensitivity one can work from two sides. First, it is possible to improve the design of the coating thiol, obtaining a monolayer with different affinities and different capability of magnetization transfer, both crucial aspects for the technique. On the other hand, it is possible to im-prove sensitivity by acting directly on the type of NMR experiment used as well, also in combination with tricks that exploit magnetization enhancement, such as using the water trapped in the monolayer as an additional magnetization source or using the capability of gold nanoparticles to self-assemble on silica nanospheres, in order to enhance the nanoreceptor’s size. Combining all the various things, I will demonstrate how it is possible to sense inorganic species too, such as K+, which do not have an NMR signal per se. Finally, as NMR is not, as of now, a technique that is easy to apply for on-field analysis, in the last part of this paper I propose a point-of-care sensor developed in the form of an indicator strip in which a self-assembled supramolecular receptor composed of a cucurbituril and a dye can selectively sense the presence, or not, of a drug in a quick, safe and cheap way.
In questa tesi ho descritto e discusso i risultati ottenuti nell’ambito di un progetto di ricerca focalizzato sull’applicazione e lo sviluppo della tecnica dell’NMR-chemosensing. Questa tecnica è basata sulla combinazione di nanoparticelle d’oro da 2 nm di diametro passivate con opportuni tioli e di particolari esperimenti NMR e consente di “estrarre” dallo spettro NMR di una miscela di composti lo spettro NMR dell’analita riconosciuto dalla nanoparticella. In particolare, lo scopo primario del mio lavoro è stato dimostrare come questa tecnica possa essere usata con successo per il rilevamento delle cosiddette “designer drugs”. La maggior parte delle nuove droghe immesse sul mercato ogni anno altro non sono che analoghi strutturali di droghe già diffuse. Ciò rappresenta un grave problema di salute pubblica, perché non essendo queste nuove sostanze mai state studiate, non se ne conoscono i potenziali rischi e gli effetti a lungo termine. In più, non esistendo standard di riferimento, la loro rilevazione con tecniche tradizionali risulta difficoltosa. La tecnica che verrà descritta è stata testata e funziona anche su campioni reali, senza bisogno di pretrattamento del campione, e dà la possibilità di arrivare dal sequestro alla caratterizzazione strutturale della sostanza stupefacente nel giro di poche ore. Dimostrerò anche che per migliorare le potenzialità dell’NMR-chemosensing in termini sia di sensibilità che versatilità si può agire su un doppio fronte. Da un lato, è possibile migliorare la struttura del tiolo che ricopre le nanoparticelle, ottenendo un monostrato con maggior affinità e maggior capacità di trasferimento della magnetizzazione, entrambi aspetti fondamentali della tecnica. Dall’altro, è possibile migliorare la sensibilità agendo direttamente sul tipo di esperimento utilizzato, anche in abbinamento ad astuzie che possano aumentare l’efficienza del trasferimento di magnetizzazione, quali ad esempio usare l’acqua intrappolata nel monostrato come fonte supplementare di magnetizzazione oppure sfruttare la capacità delle nanoparticelle d’oro di autoassemblarsi su nanosfere di silice per aumentare le dimensioni del nanorecettore. Combinando tutte queste accortezze, dimostrerò come sia possibile analizzare con questa tecnica anche specie inorganiche, come K+, che di per sé non possiedono alcun segnale NMR. Infine, visto che l’NMR non è, per ora, una tecnica di facile applicazione per analisi sul campo, nell’ultima parte di questo lavoro di tesi mi sono occupato anche un sensore point-of-care sviluppato sotto forma di cartina indicatrice, in cui un recettore supramolecolare autoassemblato composto da un cucurbiturile e un colorante può indicare selettivamente la presenza o meno di sostanza stupefacenti in modo rapido, sicuro ed economico.

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Zhu, Jianfa. « Fluorescent chemosensor development based on multifunctional spirobenzopyrans ». HKBU Institutional Repository, 2011. https://repository.hkbu.edu.hk/etd_ra/1299.

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Williams, James Anthony Gareth. « Luminescence behaviour of macrocycle metal complexes ». Thesis, Durham University, 1995. http://etheses.dur.ac.uk/5313/.

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Luminescent complexes of lanthanide ions are of growing interest because the long lifetime of emission allows time-resolved detection procedures to be employed. A key step in the development of such systems lies in the preparation of highly luminescent complexes which display high stability in aqueous solution. A series of ligands based on 1,4,7,10-tetraazacyclododecane have been prepared, in which the nitrogen atoms are appended with coordinating phosphinate or amide groups, or a combination of both. The compounds obtained are octadentate ligands which form water-soluble lanthanide complexes of high stability. Complexes incorporating aryl groups in the pendent arms have been prepared and some display intense metal luminescence following excitation into the organic chromophores. A back energy transfer process occurs in the terbium complexes containing naphthyl or quinohnone groups. Measurements of the luminescence lifetimes in H(_2)O and H(_2)O show diat diere are no metal-bound water molecules in the tetrabenzylphosphinate complexes. Those incorporating one amide and three phosphinate groups display hydration states between 0 and 1. An attempt has been made to correlate this information with that obtained from an analysis of the nuclear magnetic resonance dispersion profiles of related gadolinium complexes. The complexes incorporating secondary amide groups display an additional deactivation pathway for the metal excited state involving energy transfer into N-H bonds. The luminescence behaviour of four macrocyclic tetraamide ligands incorporating naphthyl fluorophores has been studied. These compounds exhibit distinctive changes in luminescence in the presence of quenching (eg. Pb(^2+), Cu(^2+) and Ni(^2+)) and non- quenching ions (eg. Cd(^2+) and Zn(^2+)). This behaviour extends to non-aqueous solution. The protonated tetranaphthyl ligand forms an intramolecular excimer in which the excimer emission displays a sensitive dependence on the polarity of die solvent.

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Pancholi, Jessica. « Novel 'click' generated sensors and molecular machines for fluorescent sensing of Zn2+ ». Thesis, Queen Mary, University of London, 2015. http://qmro.qmul.ac.uk/xmlui/handle/123456789/15017.

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Zinc is now firmly established as an essential trace element in the human body. Whilst it has many key structural and catalytic fixed roles, it is also found in 'mobile' pools in many essential organs and organelles that are readily chelatable. The presence and trafficking of these zinc pools are thought to contribute in some form to many human disease states associated with these organs, for example, Type 2 diabetes in the pancreas, some forms of cancer in the prostate, and even ischemic stroke, epilepsy and Alzheimer's disease. The exact role however, remains largely unknown and this is due to our current limitations with the methods in which we monitor the movement of this important element in our body. This thesis presents our efforts to develop novel Zn2+ selective chemosensors that can meet contemporary criteria for successful and simple imaging. Many efforts are being made to develop simple fluorescent molecular probes to monitor the trafficking and progress of Zn2+ through these cells and organs in real time via these chelatable 'mobile' pools. Chapter 1 will outline some successful efforts towards these and discuss their relevance and mechanisms of action, as well as outlining 'click'-chemistry and its role in chemosensing to date. Chapter 2 describes a novel 'click'-chemistry approach designed to aid with the simple construction of novel zinc-chelating probes in a facile and high yielding manner. This methodology was taken forward to the synthesis of 6 novel Zn2+-selective small molecule fluorescent probes that incorporate a cell organelle targeting motif in their structure. These are described in Chapter 3, and their successful testing both in-vitro and in-cellulo in murine pancreatic islet cells is presented and discussed. Finally, Chapter 4 discusses the development of some modified fluorescent [2]rotaxanes as molecularly interlocked architectures capable of binding and sensing metals, and will specifically focus on how small structural changes led to vast differences in their fluorescence properties, ultimately resulting in a Zn2+-selective [2]rotaxane in organic media.

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Crowley-Gall, Amber. « Mechanisms underlying host shift in cactophilic Drosophila ». University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1553613245542061.

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Fink, Elie Marina-Lora 1989. « Diversity of chemosensory behaviour in the Drosophila genus ». Doctoral thesis, Universitat Pompeu Fabra, 2017. http://hdl.handle.net/10803/664282.

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This thesis work explores the diversity of olfactory behaviour of Drosophila species in a comparative approach. We identify differences in the levels of attraction of the larva of eight species, towards natural odours derived from their ecologies. We relate these differences to distinct chemotaxis strategies that arise from the unique modulation of various sensorimotor variables, as well as to genetic changes occurring at the level of the odorant receptors genes. Further, we detail the organisation of behavioural sequences of larval locomotion in different Drosophila species, and reveal unique foraging styles that result in differentiated strategies of escape and confinement responses in the presence of light gradients, known to mediate avoidance in Drosophila. We also describe the existence of striking dichotomies of odour preferences between species, resulting in a prominent shift from attraction to aversion in the Drosophila suzukii larva, and detail how this finding revealed odours with toxic modes of action, conferring paralysis on the adult fly of only some Drosophila species, and their potential application as green pesticides.
Este trabajo de tesis explora la diversidad del comportamiento olfativo de las especies de Drosophila con un enfoque comparativo. Identificamos diferencias en los niveles de atracción de la larva de ocho especies, hacia olores naturales derivados de sus ecologías. Relacionamos estas diferencias con distintas estrategias de quimiotaxis que surgen de la modulación única de varias variables sensomotoras, así como debido a cambios genéticos que ocurren a nivel de los genes de los receptores de olor. Además, detallamos la organización de las secuencias de comportamiento formando la locomoción de la larva en diferentes especies de Drosophila y revelamos estilos de forrajeo únicos que resultan en estrategias diferenciadas de reacciones de fuga o de confinamiento en presencia de gradientes de luz, conocidos por evocar reacciones de evasión en Drosophila. También describimos la existencia de dicotomías sorprendentes de las preferencias de olor entre las especies, dando como resultado un cambio prominente de la atracción a la aversión en la larva de Drosophila suzukii, y detallamos cómo esta observación reveló olores con modos tóxicos de acción, confiriendo parálisis en la mosca adulta de solamente algunas especies de Drosophila, y su posible aplicación como pesticidas ecológicos.

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Cancellieri, Paul Joseph. « CHEMOSENSORY ATTRACTION OF PFIESTERIA SPP. TO FISH SECRETA ». NCSU, 2001. http://www.lib.ncsu.edu/theses/available/etd-20010402-173118.

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Dinoflagellates represent a diverse group of both auxotrophic and heterotrophic protists. Most heterotrophic dinoflagellates are raptorial feeders that encounter prey using ?temporal-gradient sensing? chemotaxis wherein cells move along a chemical gradient in a directed manner toward the highest concentration. Using short-term ?memory? to determine the orientation of the gradient, dinoflagellates swim in a ?run-and-tumble? pattern, alternating directed swimming with rapid changes in orientation. As the extracellular concentration of the attractant increases, a corresponding increase in the ratio of net-to-gross displacement results in overall movement toward the stimulus.The dinoflagellates Pfiesteria piscicida and P. shumwayae are heterotrophic estuarine species with complex life cycles that include amoeboid, flagellated, and cyst stages, that have been implicated as causative agents in numerous major fish kills in the southeastern United States These organisms show documented ?ambush-predator? behavior toward live fish in culture, including rapid transformations among stages and directed swimming toward fish prey in a manner that suggests the presence of a strong signalling relationship between live fish and cells of Pfiesteria spp.Zoospores of the two species of Pfiesteria can be divided into three functional types: TOX-A designates actively toxic isolates fed on fish prey; TOX-B refers to temporarily non-toxic cultures that have recently (1 week to 6 months) been removed from fish prey (and fed alternative algal prey); and NON-IND refers to isolates without apparent ichthyotoxic ability (tested as unable to kill fish in the standardized fish bioassay process; or without access to fish for ca. 1.5 years). Several Pfiesteria-like dinoflagellates have been isolated from samples in which P. piscicida and P. shumwayae are also present, including several cryptoperidiniopsoid species that have repeatedly been tested as lacking ichthyotoxic capability under ecologically relevant conditions (cell densities that occur in estuaries).Microcapillary assay techniques were employed to determine the attraction of P. piscicida and P. shumwayae zoospores to sterile-filtered fish mucus and excreta. Differences in attraction were measured among functional types, and between these two species and several isolates of cryptoperidiniopsoids, in ten-minute trials in which zoospores entering tubes filled with test substances were observed and counted. TOX-A zoospores of both P. piscicida and P. shumwayae were strongly and comparably attracted to fish secreta/excreta, relative to their behavior toward microcapillary tubes that were filled with filtered seawater. TOX-B zoospores of both Pfiesteria species showed intermediate attraction toward fish materials that appeared to be inversely related to time isolated from fish prey. NON-IND zoospores exhibited low attraction to fish materials. Cryptoperidiniopsoid zoospores showed moderate attraction with no apparent influence of previous exposure to fish.In an additional experiment that examined the signal activity in fish materials over time after collection from fresh fish, unfiltered fish materials ceased to attract P. piscicida zoospores after approximately 48 hours and ultrafiltered materials maintained attractive ability over the duration of the experiment (72 hours). These data show that filtration of fish materials may be used to extend the useful life of the chemical signal, possibly by removing bacteria that consume or degrade it.In recent years, several researchers have identified fish kairomones (pheromones that benefit the recipient) present in fish mucus that induce life history and behavioral changes in a range of zooplankters. It is likely that one or more of these kairomones, or similar compounds, are responsible for the behavioral and developmental changes observed in Pfiesteria spp. in the presence of live fish. Data from these experiments support the current understanding that significant behavioral differences exist between functional types of Pfiesteria spp., and between these toxic dinoflagellate species and known lookalike dinoflagellates without ichthyotoxic activity under ecologically relevant conditions.

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Warren, Anna Victoria. « Analysis of the chemosensory operons of Rhodobacter sphaeroides ». Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275380.

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Jacobs, Stephen P. « Chemosensory proteins and odorant binding proteins in aphids ». Thesis, University of Nottingham, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435766.

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Kuntner, Jochen [Verfasser]. « Oil Condition Monitoring Using Physical Chemosensors / Jochen Kuntner ». Aachen : Shaker, 2008. http://d-nb.info/1164342134/34.

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Grantham, Andrew James. « The development of portable chemosensors for atmospheric radicals ». Thesis, University of York, 2017. http://etheses.whiterose.ac.uk/20210/.

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The complex photochemical oxidation cycles involved in the degradative removal of anthropogenic and biogenic hydrocarbons from the atmosphere are mediated by a range of radical intermediates (e.g. peroxyl radicals). Thus these radicals are of particular interest in relation to air quality and human health. Speciated measurements of atmospheric radicals pose considerable challenges to analytical chemists. Owing to their low concentrations, high reactivity and short lifetimes, free radical species cannot be easily sampled; therefore direct offline analysis is extremely difficult. Issues such as selectivity, full structure determination, portability and cost (logistics, power, expertise) remain challenging obstacles to atmospheric radical analysis. Within this thesis, the synthesis and development of a series of novel chemosensors is presented. These are organic trapping compounds that can efficiently and selectively react with a range of radical species. The chemosensor is designed with the aim of radical addition to a double bond, resulting in the loss of a stable radical leaving group. The trapped radical structure is maintained in the reaction products, which are sufficiently stable for offline mass spectrometry. This approach allows for accurate determination of the radical structures and is different to traditional spin trapping, with the captured radical now converted to a stable non radical form. The developed chemosensors have been tested and evaluated in laboratory and chamber experiments by application to a range of atmospherically relevant systems (e.g. alkene ozonolysis and reactions of .OH with alkanes), giving key insights into radical selectivity and reaction mechanisms. They have also been applied to measurements of indoor and outdoor air, providing evidence for the function of this system at atmospheric radical concentrations.

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Figueira, Flávio Alberto da Silva. « Expanded porphyrins and their evaluation as anion chemosensors ». Doctoral thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/13247.

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Doutoramento em Química
Expanded porphyrins are synthetic analogues of porphyrins, differing from the last ones and other naturally occurring tetrapyrrolic macrocycles by containing a larger central core, with a minimum of 17 atoms, while retaining the extended conjugation features that are a tremendous feature of these biological pigments. The core expansion results in various systems with novel spectral and electronic features, often uniques. Most of these systems can also coordinate cations and/or anions, and in some cases they can bind more than one of these species. In many cases, these molecules display structural features, such as non-planar structures, that have no antecedents in the chemistry of porphyrins or related macrocyclic compounds. This work will discuss several synthetic approaches for the synthesis of expanded porphyrins, namely the construction of new building blocks by Michael addition, as well as potential synthetic routes towards expanded porphyrins. The synthesis of smaller oligopyrrolic compounds namely, bipyrroles and dipyrromethanes, not only were developed for the synthesis of expanded porphyrins as they were also used in Knoevenagel condensations furnishing chromogenic compounds able to recognize different anions in solution. Also, an approach to the synthesis of novel expanded porphyrins namely sapphyrins has been done by aza-Michael additions. Several synthetic routes towards the synthesis of pyridyl and pyridinium N-Fused pentaphyrins and hexaphyrins have been explored in order to achieve compounds with potential applications in catalysis and PDI, respectively. Studies on the synthesis of compounds with potential anion binding properties, led to the structural characterization and NMR anion binding studies of [28]hexaphyrins functionalized with several diamines in the para position of their pentafluorophenyl groups. These compounds allow NH hydrogen bond interactions with various anions. All synthesized compounds were fully characterized by modern spectroscopic techniques.
Porfirinas expandidas são análogos sintéticos das porfirinas, diferindo destes apenas por possuírem um core contendo no mínimo 17 átomos. A expansão do core resulta em vários sistemas com novas características electrónicas e espectrais, e numa extraordinária química de coordenação. Em muitos casos é também possível interação supramolecular com um ou vários aniões. Outra característica interessante é a possibilidade destes macrociclos acomodarem mais do que um estado de oxidação variando as suas características de aromaticidade e planaridade sem antecedentes na química de macrociclos tetrapirrólicos e derivados. Este trabalho discute diversas rotas de síntese de macrociclos expandidos e sua derivatização, bem como a síntese de precursores bipirrólicos sobejamente conhecidos pela sua utilização como precursores na síntese de Porfirinas expandidas. Para este fim, unidades do tipo bipirrolico foram funcionalizadas através de adições de Michael. Estes pequenos compostos foram também derivatizados através de condensações de Knoevenagel para aplicação em coordenação de aniões demonstrando reconhecimento de diferentes aniões mediante uma variação de cor específica. No seguimento destes estudos de reactividade por Diels-Alder e/ou adições de Michael obtiveram-se novos derivativos do tipo safirina com substituições no interior do macrociclo. Tendo em vista a síntese de compostos com reconhecimento de aniões e potencial aplicação em PDT/PDI e catálise, macrocrociclos do tipo pentafirina e hexafirina foram derivatizados com diversos nucleófilos. Neste último, a introdução de grupos amino na sua periferia conduziu a um aumento drástico da capacidade de interação com aniões em solventes polares. Estudos de RMN com os compostos capazes de reconhecer aniões possibilitou a sua total caracterização estrutural demonstrando estruturalmente os grupos que participam no reconhecimento de aniões. Todos os compostos presentes sintetizados foram caracterizados estruturalmente com recurso a diversas técnicas espectroscópicas, nomeadamente: à ressonância magnética nuclear de protão, carbono 13 e de flúor 19, à absorção no Ultravioleta-Visível, à espectrometria de massa e sempre que possível a análise de raio-X de monocristal.

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Wolfram, Wendi K. « Scent-marking : investigating chemosensory signals in wolf urine ». Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/14207.

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Identifying the best control method for problematic wildlife is an ever present issue in wildlife management. Popular control methods have ranged from lethal techniques, extirpating the animal, to multiple non-lethal methods focused on deterring undesired behavior. In the past, lethal methods were the preferred choice. However, with increased awareness of the need for biodiversity conservation, new management methods focus on non-lethal control, with emphasis on exploiting aspects of naturally occurring organismal behaviors and ecology. Over the past decade, technological advances in extraction method’s and equipment have also developed new techniques providing a broader range of information about species biology for management use. One of the most well documented conflicts between wildlife and humans is that of the wolf. Using advanced technology and new techniques, we investigated the implication of using chemosensory signals in canid urine to modify behavior as a possible non-lethal alternative in large predator management. Here we used the SBSE method coupled with improved GC/MS equipment to analyze the volatile organic compounds in the urine of four canid species, gray wolf (Canis lupus), red wolf (Canis rufus), wolf-dog hybrids (Canis familiaris) and the domestic dog (Canis familiaris) in order to create working urinary profiles. The extraction method identified several compounds also seen in the urinary profiles of other large predators. In addition, similarities and differences were also noted between taxa and the sexes, and these can be further explored in future studies. Two identified urinary compounds, acetophenone and methyl propyl sulfide, were selected for further behavioral evaluation. We focused on these compounds and their influence as chemosensory signals triggering urine marking events in both the gray wolf and red wolf. Behavioral observations of the effects of these two chemicals indicated they elicited responses from captive wolves. At each of the three study sites, the combination of these chemicals produced urine-marking events along the territory boundary by dominant animals. As a result, the investigation focused on what triggered the urine-marking events, the chemicals themselves, their combination, or the breakdown of the chemicals producing other odorants. It was found that there was no significant degradation of the chemicals over time and environmental conditions produced no significant breakdown of the acetophenone prior to the addition of methyl propyl sulfide. This posed a number of new questions and illustrated the need for additional behavioral studies. The results of this study analyzing chemosensory signals in canid urine, provides biologists with new information to aid in the development of new non-lethal management strategies for handling problematic wildlife as well as providing useful information for future research involving reproduction, predator/prey dynamics, territory maintenance, and a host of other studies focusing on animal ecology in association with chemosensory signaling.

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Scott, Jodie Catherine. « Che6 chemosensory regulation of multicellularity in myxococcus xanthus ». Diss., University of Iowa, 2011. https://ir.uiowa.edu/etd/1077.

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Myxococcus xanthus is a δ-proteobacterium that displays a complex, multicellular life cycle involving vegetative growth, coordinated motility, and a developmental program culminating in sporulation. M. xanthus utilizes two genetically distinct yet coordinated systems to regulate motility comprised of either Type IV pili (T4P) or focal adhesion complexes (FAC). Both motility systems are regulated, in part, by multiple chemosensory systems. During development, cells aggregate into foci and gradually lose motility to become quiescent fruiting bodies containing mature heat- and sonication-resistant myxospores. In this study, I have characterized a new chemosensory system, Che6, in M. xanthus for its role in motility and development. The Che6 chemosensory system is comprised by six homologs to known chemotaxis proteins, Mcp6, CheW6a, CheW6b, CheA6, CheR6, and CheB6 and includes two previously identified proteins, a potassium efflux channel (KefC) and a sensor kinase (SocD). Mutations in each of the corresponding genes were found to affect motility and to disrupt development. Notably, the motility defects were well defined in a background strain with an impaired T4P system. In this background, the che6 mutants were observed to either positively or negatively affect reversal frequencies, highlighting their role in either FAC or T4P-based motility systems. Developmental defects were also identified for the che6 mutants and affected the timing of aggregation and sporulation. Interestingly, the overproduction of the CheB6 methylesterase resulted in spore formation independent of fruiting body formation. Uncoupling of sporulation and fruiting body formation for this mutant was found to be independent of a key developmental signal known as the C-signal. Moreover, we have demonstrated for the first time the association of a potassium efflux channel (KefC) with a chemosensory system (Che6) in bacteria. In this study, we provide evidence demonstrating that KefC provides an input signal for Mcp6 which transduces a signal through CheA to the histidine kinase SocD which serves as an output to regulate both motility and development in M. xanthus.

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Mummolo, Liviana <1992&gt. « Nanostructured luminescent chemosensors for environmental and biomedical applications ». Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amsdottorato.unibo.it/9836/1/PhD_Thesis_XXXIIIcycle_LMummolo_upload2.pdf.

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Nanomaterials are nowadays widely recognised as advantageous sensing tools due to their unique properties. Some natural nanomaterials, such as DNA or hyaluronic acid analysed in this PhD thesis, have an intrinsic biocompatibility that overcomes a series of issues in the field of sensing in biological environments. Therefore, the main aim of this project was to derivatize HA chains with luminescent dyes - both organic and metal complexes - in order to obtain natural polymer-based optical sensors. A derivatization of HA with these moieties was obtained and a photophysical characterization was provided. To prove their sensing ability towards nanomaterials, the interaction with. PluS Nanoparticles, featuring an outer PEG shell, was tested. It was mostly demonstrated that the main features of the luminophores used were present in the HA nanogels as well. For example, HA@Dansyl was proven to be a luminescent probe able to sense different environment polarities. Furthermore, in HA@PA the amount of excimers/monomers emission was found to be relatable to the degree of entanglement of HA chains, that changes upon interactions with nanoparticles. Moreover, two ruthenium bipyridyl derivatives were linked to HA and it was found out that HA interacts with long DNA sequences. Also, the presence of BPA, a small molecule of environmental concern, was detected using (i) an already studied hyaluronic acid derivative with rhodamine (HA@RB) , (ii) a dizinc ruthenium complex coordinating BPA to the metal centres, and (iii) a new probe constituted by PluSNPs@DEAC and HA@RB. Despite all the systems were found to be able to detect BPA, the latter probe presented advantages in terms of sensitivity. Furthermore, the chapter 2 of this thesis is focused on the detection of a NF-κB protein in PC3 cancer cells. via confocal microscopy by following a FRET signal variation on a triplex-hairpin derivatized with a FRET couple of dyes.

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Ziyatdinov, Andrey. « Biomimetic set up for chemosensor-based machine olfaction ». Doctoral thesis, Universitat Politècnica de Catalunya, 2014. http://hdl.handle.net/10803/285128.

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The thesis falls into the field of machine olfaction and accompanying experimental set up for chemical gas sensing. Perhaps more than any other sensory modality, chemical sensing faces with major technical and conceptual challenges: low specificity, slow response time, long term instability, power consumption, portability, coding capacity and robustness. There is an important trend of the last decade pushing artificial olfaction to mimic the biological olfaction system of insects and mammalians. The designers of machine olfaction devices take inspiration from the biological olfactory system, because animals effortlessly accomplish some of the unsolved problems in machine olfaction. In a remarkable example of an olfactory guided behavior, male moths navigate over large distances in order to locate calling females by detecting pheromone signals both rapidly and robustly. The biomimetic chemical sensing aims to identify the key blocks in the olfactory pathways at all levels from the olfactory receptors to the central nervous system, and simulate to some extent the operation of these blocks, that would allow to approach the sensing performance known in biological olfactory system of animals. New technical requirements arise to the hardware and software equipment used in such machine olfaction experiments. This work explores the bioinspired approach to machine olfaction in depth on the technological side. At the hardware level, the embedded computer is assembled, being the core part of the experimental set up. The embedded computer is interfaced with two main biomimetic modules designed by the collaborators: a large-scale sensor array for emulation of the population of the olfactory receptors, and a mobile robotic platform for autonomous experiments for guiding olfactory behaviour. At the software level, the software development kit is designed to host the neuromorphic models of the collaborators for processing the sensory inputs as in the olfactory pathway. Virtualization of the set up was one of the key engineering solutions in the development. Being a device, the set up is transformed to a virtual system for running data simulations, where the software environment is essentially the same, and the real sensors are replaced by the virtual sensors coming from especially designed data simulation tool. The proposed abstraction of the set up results in an ecosystem containing both the models of the olfactory system and the virtual array. This ecosystem can loaded from the developed system image on any personal computer. In addition to the engineering products released in the course of thesis, the scientific results have been published in three journal articles, two book chapters and conference proceedings. The main results on validation of the set up under the scenario of robotic odour localization are reported in the book chapters. The series of three journal articles covers the work on the data simulation tool for machine olfaction: the novel model of drift, the models to simulate the sensor array data based on the reference data set, and the parametrized simulated data and benchmarks proposed for the first time in machine olfaction. This thesis ends up with a solid foundation for the research in biomimetic simulations and algorithms on machine olfaction. The results achieved in the thesis are expected to give rise to new bioinspired applications in machine olfaction, which could have a significant impact in the biomedical engineering research area.
Esta tesis se enmarca en el campo de bioingeneria, mas particularmente en la configuración de un sistema experimental de sensores de gases químicos. Quizás más que en cualquier otra modalidad de sensores, los sensores químicos representan un conjunto de retos técnicos y conceptuales ya que deben lidiar con problemas como su baja especificidad, su respuesta temporal lenta, su inestabilidad a largo plazo, su alto consumo enérgético, su portabilidad, así como la necesidad de un sistema de datos y código robusto. En la última década, se ha observado una clara tendencia por parte de los sistemas de machine olfaction hacia la imitación del sistema de olfato biológico de insectos y mamíferos. Los diseñadores de estos sistemas se inspiran del sistema olfativo biológico, ya que los animales cumplen, sin apenas esfuerzo, algunos de los escenarios no resueltos en machine olfaction. Por ejemplo, las polillas machos recorren largas distancias para localizar las polillas hembra, detectando sus feromonas de forma rápida y robusta. La detección biomimética de gases químicos tiene como objetivo identificar los elementos fundamentales de la vía olfativa a todos los niveles, desde los receptores olfativos hasta el sistema nervioso central, y simular, en cierta medida, el funcionamiento de estos bloques, lo que permitiría acercar el rendimiento de la detección al rendimiento de los sistemas olfativos conociodos de los animales. Esto conlleva nuevos requisitos técnicos a nivel de equipamiento tanto hardware como software utilizado en este tipo de experimentos de machine olfaction. Este trabajo propone un enfoque bioinspirado para la ¿machine olfaction¿, explorando a fondo la parte tecnológica. A nivel hardware, un ordenador embedido se ha ensamblado, siendo ésta la parte más importante de la configuración experimental. Este ordenador integrado está interconectado con dos módulos principales biomiméticos diseñados por los colaboradores: una matriz de sensores a gran escala y una plataforma móvil robotizada para experimentos autónomos. A nivel software, el kit de desarrollo software se ha diseñado para recoger los modelos neuromórficos de los colaboradores para el procesamiento de las entradas sensoriales como en la vía olfativa biológica. La virtualización del sistema fue una de las soluciones ingenieriles clave de su desarrollo. Al ser un dispositivo, el sistema se ha transformado en un sistema virtual para la realización de simulaciones de datos, donde el entorno de software es esencialmente el mismo, y donde los sensores reales se sustituyen por sensores virtuales procedentes de una herramienta de simulación de datos especialmente diseñada. La propuesta de abstracción del sistema resulta en un ecosistema que contiene tanto los modelos del sistema olfativo como la matriz virtual . Este ecosistema se puede cargar en cualquier ordenador personal como una imagen del sistema desarrollado. Además de los productos de ingeniería entregados en esta tesis, los resultados científicos se han publicado en tres artículos en revistas, dos capítulos de libros y los proceedings de dos conferencias internacionales. Los principales resultados en la validación del sistema en el escenario de la localización robótica de olores se presentan en los capítulos del libro. Los tres artículos de revistas abarcan el trabajo en la herramienta de simulación de datos para machine olfaction: el novedoso modelo de drift, los modelos para simular la matriz de sensores basado en el conjunto de datos de referencia, y la parametrización de los datos simulados y los benchmarks propuestos por primera vez en machine olfaction. Esta tesis ofrece una base sólida para la investigación en simulaciones biomiméticas y en algoritmos en machine olfaction. Los resultados obtenidos en la tesis pretenden dar lugar a nuevas aplicaciones bioinspiradas en machine olfaction, lo que podría tener un significativo impacto en el área de investigación en ingeniería biomédica

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Gaaboub, Ibrahim Abd Alla. « Neural processing of chemosensory information from the locust legs ». [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=961248831.

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Tousson, Ehab Mostafa. « Neural processing of chemosensory information from the locust ovipositor ». [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=961892293.

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Bokeloh, Frank. « Development of organic microelectromechanical chemosensors based on fiber optics ». Thesis, Compiègne, 2017. http://www.theses.fr/2017COMP2381.

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Un (bio)capteur classique est principalement composé de deux éléments essentiels : une couche réceptrice sensible à l’analyte à laquelle on s’intéresse et un transducteur qui permet de convertir une stimulation chimique / biologique en un signal physique mesurable. Dans le cas idéal, un capteur ne doit pas nécessiter de marquage de la cible, doit posséder de très grandes sensibilité et sélectivité envers elle, ne requiert qu’une faible quantité de cette dernière et doit présenter un temps de réponse très court. Au vu de ces critères, les microsystèmes électromécaniques (MEMS) sont des candidats très prometteurs dans le développement de capteurs. Les polymères fonctionnels, tels que les polymères à empreinte moléculaire (MIPs), sont une approche très intéressante dans l’utilisation des MEMS car ils peuvent être intégrés dans des technologies existantes de MEMS à base de silicium ou complètement remplacer ces technologies. Le but de cette thèse porte sur le développement d’un capteur MEMS composé de polymères (fonctionnels). Un chapitre initial (chapitre 2) introduit des nouveaux systèmes de fabrication de polymères fonctionnels. Des biopuces composées de MIPs imprimés par jet d’encre sont présentées ainsi qu’une technique basée sur la polymérisation radicale contrôlée qui permet le dépôt d’un fin enrobage de MIPs sur des microstructures. La deuxième partie de ce chapitre présente la fabrication de polymères à empreinte moléculaire par stéréolithographie deux-photons, qui peut être vue comme une extension de l’impression 3D. Afin d’illustrer cette technologie de prototypage rapide, deux capteurs composés de MIPs sont présentés : un capteur à grille de diffraction et un capteur en microlevier. Les deux principaux chapitres de ce manuscrit (chapitre 3 et 4) se focalisent sur le développement d’un nouveau concept de fabrication pour les capteurs MEMS. Ce concept est basé sur la polymérisation d’une poutre à fort ratio de forme à l’extrémité d’une fibre optique de télécommunication. Cette poutre a été mise en vibration à sa résonnance et a ainsi pu être utilisée comme un capteur à base de levier. Le capteur en polymère a permis l’intégration de MIPs comme élément récepteur et la reconnaissance sélective de l’antibiotique enrofloxacine. De plus, un nouveau système de mesure intégré est présenté dans le chapitre 4. Ce système de mesure intègre la fibre optique en guidant un rayon laser à travers elle ainsi qu’à travers le levier qui y est attaché.Le rayon lumineux sortant est ensuite focalisé sur une photodiode sensible à la position du rayon lumineux, permettant ainsi la mesure du spectre de résonance de la poutre en polymère. Ce système de mesure est caractérisé et ses performances sont présentées au travers de la détection de masse du levier en polymère et de mesures faites en milieu liquide
A classical (bio)sensor consists of two key components: A receptor layer that detects the analyte of interest and the transducer which converts the chemical / biological stimuli into a physical measurable signal. Ideally a sensor is label-free, highly sensitive and selective towards the target, requires low sample amount and shows a fast response time. Regarding these criteria microelectromechanical systems (MEMS) offer great potential for the sensor development. One interesting approach for this development are functional polymer materials, such as molecularly imprinted polymers (MIPs), that can be either integrated to existing MEMS based on silicon or completely replace the silicon technology. The emphasis of this thesis is focused on the development of a MEMS sensor based on (functional) polymers. In an initial chapter (chapter 2) new fabrication schemes for functional polymers are introduced. Inkjet-printed biochips based on MIPs are presented and a technique based on controlled radical polymerization is shown that allows the deposition of thin MIP shells on a microfabricated pattern. In the second part of this chapter the fabrication of molecularly imprinted polymers by two-photon stereolithography is shown which can be seen as an extension of 3dimensional printing. As possible application of this rapid prototyping technology two sensors based on MIPs are introduced a diffraction grating sensor and a microcantilever sensor. The two main chapters of this manuscript (chapter 3 and chapter 4) report the development of a new fabrication concept for MEMS sensors. It is based on the polymerization of a high aspect ratio beam on the extremity of an optical telecommunication fiber which was actuated at resonance and thus could be used as a cantilever sensor. The polymer sensor allowed the integration of MIPs as sensing element and the selective recognition of the antibiotic enrofloxacin. Furthermore, is a new, integrated read-out scheme presented in chapter 4. This read-out scheme integrates the optical fiber, by guiding a probe laser beam through it and attached cantilever beam. The output light beam is then focused on a position sensitive photodiode and thus enabled to monitor the resonance spectra of the polymer beam. The read-out scheme is characterized and its performance is shown by demonstrating the mass sensitivity of the polymeric cantilever beam and by measurements in liquid environments

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Crisinel, Anne-Sylvie. « Tasty sounds : crossmodal associations between chemosensory and auditory stimuli ». Thesis, University of Oxford, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.558524.

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The sensory evaluation of food products prior to and during ingestion is a vital process. As such, it is influenced by a variety of factors, comprising both contextual cues and sensory features of the food. The research presented in this thesis was designed to explore the crossmodal associations between auditory (musical notes) and chemosensory stimuli. The reported experiments revolve around three main goals. The first goal was to demonstrate the existence of reliable crossmodal associations between auditory and chemosensory stimuli. To this end, both implicit and explicit tasks were used. Specific pairings of basic tastes, flavours, and odours with musical notes were shown to be preferred, both in term of the pitch of the note and its timbre. The second goal was to suggest potential mechanisms or factors underlying these crossmodal associations. Two such factors were studied: familiarity and pleasantness. The familiarity with the chemosensory stimuli appeared not to affect much the crossmodal associations with musical notes. The pleasantness of the chemosensory stimuli was a main factor in the associations with the timbre of the note, but failed to satisfactorily explain the associations with the pitch of the note. Finally, the third goal was to evaluate the influence the congruence of auditory stimuli might have on the perception of simultaneously-presented chemosensory stimuli. Background soundtracks were shown to influence ratings of a food item on the bitter-sweet continuum. No such effect was observed when musical notes were presented simultaneously with odours. The research reported in this thesis constitutes the first detailed account of crossmodal associations between musical notes and a variety of chemosensory stimuli. The level at which such crossmodal associations might happen, as well as potential applications, are discussed, as well as possible directions for further research on the topic.

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Hartley, Lauren Elizabeth. « Characterisation of the Aspartate Chemosensory Receptor of Campylobacter jejuni ». Thesis, Griffith University, 2009. http://hdl.handle.net/10072/366822.

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Campylobacter jejuni is a highly motile bacterium that responds via chemotaxis to environmental stimuli to migrate towards favourable conditions. Previous in-silico analysis of the C. jejuni strain NCTC 11168 genome sequence identified ten open reading frames, tlp1-10, that encode putative chemosensory receptors. This study describes the characterisation of the role and ligand specificity of the Tlp1 chemoreceptor of C. jejuni 11168-0 (Cj1506c).
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Medical Science
Griffith Health
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Hull, Mark Q. « The role of semiochemicals in the behaviour and biology of Lepeophtheirus salmonis (Kroyer, 1837) : potential for control ? » Thesis, University of Aberdeen, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310772.

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The role of semiochemicals in the behaviour and biology of Lepeophtheirus salmonis was investigated using a range of techniques. The potential use of semiochemicals in the behavioural ecology of mobile stages was examined using longitudinal monitoring and experimental manipulation of laboratory reared single cohort populations. The chronic and long term effects of separation from the host were also investigated using similar populations. The nature and chemosensory capability of the sense system of the parasite was assessed through morphological and ultrastructural studies. Finally, the nature of potential chemical stimuli during initial copepodid settlement, pair formation and mating, and host re-attachment of mobile stages, was examined using both in vitro and in vivo techniques. Longitudinal monitoring of populations created a model for mobile development and the timing and processes of pair formation and mating. There was evidence of a hierarchy of pair formation between female stages, periods of strong mate competition between males, and many factors within the processes were defined. Survival off the host was strongly related to the developmental stage and/or size of the louse; with adult females surviving for the longest and preadult I males for the shortest periods. The ability of adult males to re-attach and subsequently persist on the host was significantly reduced after only 72 hours of separation. Very few potential chemosensory setae were found on the appendages examined, the exception to this being the antennule. Two distinct populations of setae on the distal (14 setae) and proximal (27 setae) articles of the antennule demonstrated a wide range of morphology. The internal organisation, innervation and ultrastructure of these antennular setae was examined in detail. The setae could be divided into at least 6 distinct categories, when the internal data were combined with the external morphology.

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Richgels, Phoebe K. « Association of naturally occurring polymorphisms in odorant receptors with variation in olfactory behavior in Drosophila melanogaster ». University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1307043748.

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Gill, Daljeet Singh. « Olfactory development models driven by population coded chemosensor input ». Thesis, University of Leicester, 2004. http://hdl.handle.net/2381/30216.

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The early olfactory pathway has recently emerged as an important region in the central nervous system (CNS) in the study of neuronal development. It presents a remarkable wiring problem where millions of olfactory receptor neurons (ORNs) converge onto a few thousand points of integration in the olfactory bulb (OB). In addition, the continual turnover of ORNs allows development to be studied in adult organisms. In this thesis, the generation of a topographic map in the OB is investigated through models driven by high-density optical chemosensor arrays possessing similar properties to ORNs. The classical models of Von der Malsburg and Willshaw based on activity-dependent competition in the visual system are adapted to examine axonal targeting in the developing OB as uncovered by the above-mentioned experimental studies. The models, after exposure to relevant chemical stimuli, establish an appropriate connection scheme, and simultaneously identify the sensor types within arrays containing randomly dispersed microbeads - hence solving the so-called sensor decoding problem. Moreover, the final model also predicts a potential role for periglomerular cells in the formation of the olfactory topographic map. The data generated from the sensor arrays whilst exposed to various odours, are analysed statistically beforehand to ensure they form a suitable input to the models. In the process, both odour and sensor type discrimination analyses are demonstrated achieving high classification rates. This marks the first attempt to model the activity-dependent development of the early olfactory pathway. Furthermore, all models are driven by realistic input data to demonstrate robust performance.

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Yuan, Hongyan. « Development of mode-filtered light chemosensor and its applications ». HKBU Institutional Repository, 2002. http://repository.hkbu.edu.hk/etd_ra/422.

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Bertrand, Jacob Joseph. « Genetic analysis of the Chp chemosensory system of Pseudomonas aeruginosa ». Diss., Search in ProQuest Dissertations & ; Theses. UC Only, 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3378483.

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Pisut, Daniel P. (Daniel Peter). « The distance chemosensory behavior of the sea urchin Lytechinus variegatus ». Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5129.

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Many organisms that lack vision rely on chemical signals to glean information from their environment. Little is known, however, about the ability of sea urchins to detect and respond to such signals. This lack of understanding is especially surprising given the ecological impact of urchins in their respective communities. Regardless of geography, urchins exert strong top down control of plants, algae, and sedentary invertebrates, and these effects are especially evident when urchins, or urchin predators, are removed from an ecosystem. Facultative omnivorous species such as Lytechinus variegatus may greatly alter the abundances of other invertebrates in seagrass communities by preying on juvenile and adult bivalves as well as gastropod egg masses. These potential food resources, however, are patchily distributed within seagrass beds. To find such resources before other organisms can exploit them may require acute abilities to detect signals emanating from these patches. Experiments performed in this study demonstrated a consistent ability of L. variegatus to detect and orient to chemicals emanating from potential food resources over a distance of 1 m. Unlike what has been found in some other marine organisms, turbulent flow conditions did not negatively affect the ability of L. variegatus to find the source of this chemical cue. In fact, only the slowest flows hindered this ability; the bluff shape of the urchin formed a relatively large boundary layer at slow flows, preventing the delivery of chemical signals to the sensors. The relatively high success rates of L. variegatus in turbulent flows may allow it to effectively forage in areas where other organisms cannot. Thus, turbulence may provide a selective advantage for this animal, based on its comparative ability to detect and respond to signals in its environment.

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Moeller, Lisa Marie [Verfasser]. « Physiological characterization of chemosensory mechanisms in mice / Lisa Marie Moeller ». Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2014. http://d-nb.info/1065960441/34.

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Turkewitsch, Petra. « The synthesis of fluorescent chemosensors responsive tocAMP and other nucleotides ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0018/NQ44611.pdf.

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Riordan, Jr Timothy J. « Chemosensory-Mediated Deposit Feeding in the Spionid Polychaete Dipolydora Quadrilobata ». Fogler Library, University of Maine, 2001. http://www.library.umaine.edu/theses/pdf/RiordanTJ2001.pdf.

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Thompson, Stephen Richard. « A study of multiple chemosensory gene homologues in Rhodobacter sphaeroides ». Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436968.

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You, Qihua. « Development of fluorescent chemosensors based on different signal transduction mechanisms ». HKBU Institutional Repository, 2014. https://repository.hkbu.edu.hk/etd_oa/95.

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A series of fluorescent probes based on different signal transduction mechanisms for the detection of Fe3+, Zn2+, histidine and pH was designed and synthesized. Their photophysical properties, binding abilities and the further application in cell imaging were fully evaluated. Building on the groundwork of our previous study, molecular scaffold 19 has been appended to spirobenzopyran fluorophore to furnish a highly selective and sensitive Zn2+ sensor. To broaden the application scope of this trifunctional receptive molecule, 19 was incorporated onto rhodamine, antipyrine and coumarin moieties to give 20, 21 and 23, respectively. Probe 20 operative on a chelation-enhanced fluorescence mechanism exhibited highly selective response to Fe3+ with 2:1 stoichiometry of 20-Fe3+ complex. However, a possible tendency of probe 20 to hydrolyze induced by Fe3+ and the unsuccessful attempt of cell imaging would limit its application scope. Probe 21 with O-N-N-N-N-ligand showed a highly selective and sensitive detection of Zn2+. The probe displayed suppressed response to Cd2+ which is the most common interference ion in zinc metal detection. The binding of Zn2+ to probe 21 inhibited the photoinduced electron transfer process originating from the lone pair of the nitrogen atom in the antipyrine moiety to quinoline fluorophore. Therefore, a turn-on fluorescent probe was developed. A moderate binding constant with 1:1 stoichiometry of 21-Zn2+ complex was established by fluorescence titration. The binding mechanism was fully explained by 1H NMR titration. To our delight, probe 21 was successfully applied for recognizing Zn2+ in living cells. The preparation of probe 23 was achieved by appendage of 19 to coumarin derived fluorophore and the probe exhibited a good selectivity and fluorescent turn-off property to Cu2+. The 1:1 stoichiometry of 23-Cu2+ ensemble can serve as an efficient probe for the detection of histidine and biothiols. In the presence of NEM, the influence of biothiols could be eliminated. Furthermore, this sensing ensemble was also used in the detection of histidine in hard-to-transfect U87MG cells with very low cytotoxicity. Based on our group’s previous work on the spiropyran platform, a novel ratiometric near-infrared pH probe 27 operating on an excited-state intramolecular electron transfer mechanism was developed. The pKa was calculated to be 5.9 and the ring-opening/ring-closing mechanism triggered by protons was reasonably explained by 1H NMR titration. However, this spiropyran-based probe was found to be unsuitable for cell imaging. To continue the innovation of pH sensing and extend its application in bioimaging, a series of ratiometric pH probes 32 and 38 characterized by their high quantum yield working in the NIR range was developed. The appendage of N,O-disubstituted hemiaminal ether moiety onto coumarin fluorophore with C=C double bond conferred the sensory material with the ability to display a pH-dependent ratiometric output operating on the ring-opening/ring-closing mechanism. The pKa of 32 and 38 were 6.9 and 5.8 – 6.0, respectively, which rendered them suitable for pH measurement in near-neutral and acidic media. A preliminary work of intracellular pH measurement was also conducted and promising results were obtained

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Pisut, Daniel P. « The distance chemosensory behavior of the sea urchin Lytechinus variegatus ». Connect to this title online, 2004. http://etd.gatech.edu/theses/available/etd-01052004-121047/.

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Thesis (M.S.)--Georgia Institute of Technology, 2004.
Title from PDF t.p. (viewed on Oct. 28, 2006). Julia Kubanek, Committee Member; Mark Hay, Committee Member; Marc Weissburg, Committee Chair. Includes bibliographical references (p. 47-51).

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Shah, Alok Shirish. « Structural maintenance and chemosensory function of human airway motile cilia ». Diss., University of Iowa, 2009. https://ir.uiowa.edu/etd/2983.

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Cilia are finger-like projections that extend from the surface of most cells. These microtubule-based structures serve important mechanical or sensory functions. Motile cilia have been implicated in fluid movement whereas the non-motile primary cilia have been shown to play a role in sensory signal transduction. There exists a dichotomy in the field that primary cilia have only sensory function and motile cilia only have mechanical function. The central question of this thesis project is "what are the structural and functional components of airway motile cilia and are these cilia sensory?" In Chapter 2, the role of Bardet-Biedl Syndrome (BBS) proteins in maintaining the structure and function of airway motile cilia is examined. We found that BBS proteins localize to the cilium and to ciliary-related structures in human airway epithelia. Using mutant mice we found that BBS proteins play an essential role in motile cilia structure and the loss of BBS proteins results in reduced ciliary beat. These proteins have previously been shown to play a role in primary cilia structure and function, and our studies indicate a novel function for BBS proteins. Chapter 3 examines the sensory role of motile cilia. Our data show that bitter taste receptors and components of the bitter taste signal transduction pathway localize to the motile cilia or to the ciliated cells. Ciliated cells also show an increase in intracellular calcium in response to bitter compounds, accompanied by a corresponding increase in cilia beat. The increase in intracellular calcium originates at the ciliated cells and is propagated to adjacent cells. Chapter 4 delves into the possibility that every motile ciliated cell also contains a single, primary cilium. Using immunostaining and Smoothened as a marker for primary cilia, we found that every group of motile cilia contains a single Smoothened-positive cilium. Furthermore, downstream components of the Sonic Hedgehog pathway are also present in ciliated cells. Chapter 6 is a summary chapter including possible explanations for observed outcomes and plans for future experiments. Our results indicate that the divide between primary and motile cilia may not be as great as has been previously thought.

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Darnell, Cynthia Lynn. « Chemosensory regulation of development and heme homeostasis in Myxococcus xanthus ». Diss., University of Iowa, 2014. https://ir.uiowa.edu/etd/2063.

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Bacterial physiology and behavior is controlled by complex regulatory networks. Chemosensory systems are sophisticated signal transduction systems that can govern a range of cellular functions beyond that of traditional flagellar-based chemotaxis. The soil bacterium Myxococcus xanthus encodes eight chemosensory systems regulating multiple behaviors, including motility, exopolysaccharide production, and development. This work characterizes the Che7 system and demonstrates a role for Che7 in coupling aggregation and sporulation during multicellular development. The regulation requires an interaction between a single domain response regulator (CheY7) and a HEAT-repeat protein (Cpc7). A fatty acid desaturase, Des7, also impacts development in concert with the Che7 signaling system. Genetic analysis indicates the target of Che7 regulation is in the heme biosynthesis pathway, which is one aspect of iron homeostasis. Finally, characterization of iron and iron-responsive elements during development reveal a novel regulator, Fur2, that controls timing of development as well as che7 transcription. This work provides expands the known network regulating development in M. xanthus.

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