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1
Mouw, Ted. "Gravity's Rainbow: Modernist Discourse Vineland: Postmodernist Discourse." Oberlin College Honors Theses / OhioLINK, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=oberlin1397142953.
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Oliveira, Ana Valeria Duarte. "Avaliação do impacto da cirurgia de epilepsia no desenvolvimento de crianças com epilepsia refratária." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/17/17140/tde-22082017-170746/.
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A epilepsia é uma desordem cerebral definida por pelo menos duas crises não provocadas ocorrendo em um intervalo maior que 24 horas, uma crise não provocada e uma probabilidade de futuras crises similar ao risco de recorrência geral depois de duas crises não provocadas (pelo menos 60%) nos próximos 10 anos; ou o diagnóstico de uma síndrome epiléptica. Após o diagnóstico do tipo de epilepsia, existem situações em que o paciente não responde ao tratamento medicamentoso, apresentando pelo menos uma crise epiléptica por mês por um período mínimo de 2 anos. Se durante esse período, dois ou três diferentes fármacos antiepilépticos foram utilizados em monoterapia ou politerapia, e o paciente não obtém controle das crises, configura-se o quadro de epilepsia farmacorresistente. A intervenção cirúrgica é uma opção para essas crianças, atuando no controle das crises e, potencialmente no desenvolvimento neuropsicomotor. Neste estudo, avaliamos as variáveis clínicas como a idade de início da epilepsia, duração da epilepsia, frequência de crises, etiologia e a Escala de Comportamento Adaptativo de Vineland (ECAV) para caracterizar aspectos referentes aos domínios da comunicação, socialização, habilidades diárias e habilidades motoras, no período pré e pós-operatório de cirurgia de epilepsia. A nossa intenção foi determinar o impacto da cirurgia de epilepsia no desempenho dos pacientes nessas esferas avaliadas pela ECAV. Como resultados, encontramos que o grupo de participantes livre de crises após a cirurgia de epilepsia apresentou melhor desempenho cognitivo na segunda avaliação pós-operatória, quando comparado ao grupo que não teve controle de crises. A variável clínica duração da epilepsia influenciou a equivalência etária e as pontuações padrão da ECAV no período pré-operatório, sendo considerada determinante para o atraso neuropsicomotor dos pacientes submetidos à cirurgia de epilepsia. Quanto aos fatores preditivos de melhora das crises pós-operatórias, observou-se que Engel e cirurgia foram as variáveis consideradas significativas. A maioria dos pacientes (63,9%) na segunda avaliação pós-operatória ainda apresentou convulsões ou não obteve melhora. Nos achados da investigação sobre o impacto das crises em relação ao desenvolvimento neuropsicomotor na primeira avaliação 21,3 meses após a cirurgia, foi observado um ganho abaixo do esperado de apenas 4,4 meses na equivalência etária, não evidenciando melhora em curto prazo após a cirurgia, independente do controle de crises. Após 41,3 meses do procedimento cirúrgico os pacientes que apresentaram controle de crises tiveram ganhos adaptativos significativos de 15 meses na equivalência etária quando comparados com os que não apresentavam controle das crises. Nesses últimos pacientes, a equivalência etária permaneceu praticamente estável com um incremento de apenas 3 meses quando analisada as fases pré e pós - operatóriaEpilepsy is a disease of the brain defined by at least two unprovoked seizures occurring 24 h apart, one unprovoked seizure and a probability of further seizures like the general recurrence risk (at least 60%) after two unprovoked seizures, occurring over the next 10 years or diagnosis of an epilepsy syndrome. After epilepsy diagnosis, there are situations where patients do not respond to drug treatment, developing one seizure per month for a minimum of 2 years. If during this period two or three antiepileptic drugs different used as monotherapy or in combination, a condition known as drug-resistant epilepsy. Epilepsy surgery is an option for children with drug-resistant epilepsy acting on the seizure control seizures and, potentially on neuropsychomotor development. In this study, we evaluated clinical variables such as epilepsy age of onset, epilepsy duration, seizure frequency, etiology and adaptive behavior scale of Vineland to characterize aspects related to age equivalence through the domains of communication, socialization, daily skills and motor skills pre- and post-surgical period. Our intention was to determine the impact of epilepsy surgery on the performance of patients in these areas evaluated by Vineland. Thus, we found that the seizure free group participants showed better cognitive performance in the second evaluation, compared to the group that not seizure controlled. The clinical variable duration of epilepsy influenced the age equivalence and standard Vineland scores in the preoperative period, being considered determinant for the neuropsychomotor delay of patients submitted to epilepsy surgery. Regarding the predictive factors of improvement of postoperative crises, it was observed that Engel and surgery were the variables considered significant. The majority of the patients (63.9%) in the second postoperative evaluation still had seizures or did not improve. The findings of the research on the impact of crises on neuropsychomotor were that in the first evaluation 21.3 months after surgery there was a below-expected gain of only 4.4 months of age equivalence, not showing improvement in the short term after surgery, independent of control crisis. After 41.3 months of the surgical procedure, the patients presenting with seizure control had significant adaptive gains of 15 months when compared to those without seizure control. In the latter patients, the age equivalence remained practically stable with an increase of o preoperative only 3 months, analyzing the phases pre and postoperative evaluation
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Taylor, Kay M. "The problem of choice, and Karmic structure in Thomas Pynchon's Vineland /." Title page and introduction only, 1992. http://web4.library.adelaide.edu.au/theses/09AR/09art243.pdf.
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Stern, Megan. "The poetics of technoscience in Thomas Pynchon's Gravity's Rainbow and Vineland." Thesis, University of Kent, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296719.
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Oliveira, Luisa Abruzzi de. "Análise transcricional dos genes do sistema ISC em EUCALYPTUS GRANDIS e AZOBACTER VINELAND." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/61437.
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Os cofatores de ferro-enxofre [Fe-S] estão entre os mais versáteis e antigos cofatores enzimáticos encontrados na natureza. As células têm explorado as propriedades eletrônicas e estruturais destes cofatores inorgânicos para uma ampla variedade de atividades incluindo a transferência de elétrons, a catálise e a ativação de substratos. Um grande número de proteínas está envolvido na biogênese dos cofatores [Fe-S], e este processo pode ser dividido em três etapas principais: (i) formação do enxofre elementar, (ii) montagem do cofator [Fe-S], e (iii) inserção do cofator em apoproteínas. As plantas realizam fotossíntese e respiração, dois processos que requerem proteínas Fe-S, sendo os únicos organismos em que a biossíntese destas proteínas é compartimentalizada. Diversos fatores afetam o desenvolvimento das plantas, entre eles, a temperatura baixa, fator limitante à produtividade e à distribuição geográfica das plantas, incluindo Eucalyptus grandis, uma espécie com grande importância econômica. Devido a esse fato, foi realizada uma análise transcricional dos genes codificados pelo sistema ISC de biossíntese de cofatores [Fe-S] NFS1, ISA1 e ISU1 de E. grandis por meio de PCR quantitativa (RT-qPCR), após plântulas desta espécie serem submetidas ao tratamento de frio. O gene NFS1 teve sua expressão reprimida nas primeiras 48 horas de tratamento, porém, após esse período observa-se um aumento da expressão gênica em relação à condição controle. O genes ISU1 e ISA1 apresentaram maior expressão gênica nas primeiras duas horas de tratamento, diminuindo drasticamente logo após este período. Foi verificado um aumento na quantidade relativa de Fe e S nos nas plântulas submetidas ao tratamento de frio, indicando um possível aumento na quantidade de cofatores [Fe-S] requeridos para o reestabelecimento da homeostase celular. As bactérias, por sua vez, desenvolveram pelo menos três sistemas de biossíntese, altamente conservados, que estão envolvidos na formação dos cofatores [Fe-S], sendo estes NIF, ISC e SUF. Em muitas proteobactérias, a regulação da produção de cofatores [Fe-S] pelos sistemas ISC e SUF é controlada por uma única proteína, IscR, pertencente à família de reguladores Rrf2. A proteína IscR possui um domínio de ligação ao DNA na região N-terminal e um segundo domínio de ligação de cofatores com três resíduos de cisteínas (Cys) altamente conservados. A ligação de um cofator do tipo [2Fe-2S] reprime a transcrição do seu próprio promotor in vitro. O genoma de Azotobacter vinelandii não inclui um sistema SUF completo e, portanto, permite o estudo dos efeitos da regulação de IscR não relacionada a SUF. No presente trabalho, objetivamos analisar a expressão do operon isc em linhagens selvagens e mutantes para IscR de A. vinelandii por meio das técnicas de sequenciamento do transcritoma e RT-qPCR. As substituições das Cys92, Cys104, His107 e a deleção de 120 pb da região codificadora do segundo domínio de IscR levaram à indução de um aumento da expressão de todo o operon isc. Notou-se também uma diferença fenotípica clara no tamanho das colônias portadoras das substituições de Cys e His, sendo estas menores em relação à linhagem selvagem. As substituições das Cys98 e Cys111, ou ainda a dupla substituição Cys98/111 não levaram a alteração da expressão do operon. A ligação ou não do cofator [Fe-S] é, portanto, responsável pela regulação do operon isc em A. vinelandii, bem como, de outros operons codificadores de proteínas envolvidas em cadeias tranportadoras de elétrons.The iron-sulfur clusters [Fe-S] are among the oldest and most versatile enzyme cofactors found in nature. The cells have explored the structural and electronic properties of these inorganic clusters for a wide variety of activities including electron transfer, catalysis and activation of substrates. A large number of proteins is involved in the biogenesis of the [Fe-S] clusters, and this process can be divided into three main steps: (i) formation of elemental sulfur, (ii) assembly of the [Fe-S] cluster and (iii) insertion into apoproteins. Plants perform photosynthesis and respiration, two processes that require Fe-S protein, and in these organisms the synthesis of these proteins is compartmentalized. Several factors affect the development of plants, among them, the low temperature is a limiting factor to productivity and geographical distribution of plants, including Eucalyptus grandis, a specie with great economic importance. Due to this fact, we performed a transcriptional analysis by quantitative PCR (RT-qPCR) of the genes encoded by the E. grandis [Fe-S] cluster ISC system NFS1, ISA1 and ISU1 after seedlings were submitted to the chilling treatment. The NFS1 gene expression is repressed in the first 48 hours of treatment, but after this period there was an increase in gene expression relating to the control condition. The genes ISU1 and ISA1 showed higher gene expression in the first two hours of treatment, followed by a sharp decrease. There was an increase in the relative amount of Fe and S in the seedlings subjected to cold treatment, indicating a possible increase in the amount of [Fe-S] clusters, required for the reestablishment of cellular homeostasis. Bacteria have developed at least three synthesis systems, highly conserved, which are involved in the formation of Fe-S proteins, NIF, ISC and SUF. In many proteobacteria, the regulation of clusters production by ISC and SUF is controlled by a single protein, IscR, belonging to the Rrf2 regulators family. The protein IscR has a DNA binding site at the N-terminal domain and second cofactors binding domain with three cysteine residues (Cys) highly conserved. The binding of a [2Fe-2S] cluster represses the transcription of its own promoter in vitro. The genome of Azotobacter vinelandii does not include a full SUF system and thus permits the study of the effects of IscR regulation unrelated to SUF. In this study, the aim was to analyze the expression of isc operon in wild type and mutant strains of A. vinelandii IscR by the techniques of the transcriptome sequencing and qRT-PCR. The replacement of Cys92, Cys104, His107 and a deletion of 120 bp region encoding the second IscR domain led to an increased expression of the whole isc operon. It also showed a clear phenotypic difference in colonies size in the strains carrying the substitutions of His and Cys, it was smaller compared to the wild type strain. The replacement of Cys98 and Cys111, or the double substitution Cys98/111 not led to an altered operon expression. The [Fe-S] cluster binding or not, is therefore responsible for the regulation of the isc operon in A. vinelandii as well as of other operons encoding proteins involved in electron tranport chains.
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Stewart, Anne Catherine. ""No way to return" : agentic assemblies, switchback resistance, and spatializing Thomas Pynchon's narrative politics in Vineland." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/42831.
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This thesis focuses on one of the least acclaimed novels in Thomas Pynchon’s canon, Vineland. It was reviewed with disappointment by critics like Brad Leithauser, who writes that Vineland falters “chiefly through its failure in any significant degree to extend or improve upon what the author has done before.” I argue against such a reading, and position Vineland as a critical turning point for Pynchon’s work in which his articulation of the relationship between humans and nonhumans is dramatically refigured. I do this by reconsidering the history of American countercultural politics presented in Vineland in two distinct ways. First, attending to Pynchon’s critical interest in landscapes and urban spaces, I argue that the novel’s histories should be read as conceptual objects, materially coded into the landscape in such a way that they speak through these landscapes. Second, continuing to focus on ways in which space and materiality function in this novel, I draw out the nonhuman actors at work in the narrative in order to demonstrate a shift in Pynchon’s conceptualization of the relationship between what he often refers to as the animate and inanimate worlds. While his earlier novels posit an inanimate world that is threatening to humans, Vineland’s human-nonhuman dynamic is far more entangled in terms of its investment in how these actors function in assembly with each other. I pay particular attention to what Jane Bennett calls “agentic assemblages,” groupings of human and nonhuman materialities—a storm or a power grid, a city or a bioregion—that function together to author the spaces that they occupy in this novel. At stake here is a refiguring of historical agency as the product of a web of competing human and nonhuman discursive strategies. I argue that the novel’s narrative politics is one in which nonhumans have an authorial role, and that its form repeats this politics by deploying a spatial and discursive navigational strategy for human actors living in a world which is fundamentally nonanthropocentric. Through this narrative politics, Vineland emerges as a major contribution to late-20th century critical thought on spatiality, political ecology, materialist philosophy, and narrative theory.
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Dunkel-Jackson, Sarah Marie. "PEAK FOR IBI: EXAMINATION OF THE UTILITY OF THE PEAK RELATIONAL TRAINING SYSTEM FOR INTENSIVE BEHAVIORAL INTERVENTION." OpenSIUC, 2016. https://opensiuc.lib.siu.edu/dissertations/1306.
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The current set of experiments examined the utility of implementing the Promoting the Emergence of Advanced Knowledge (PEAK) Relational Training System (Dixon, 2014a, 2014b), an empirically validated assessment and intervention guide developed for children diagnosed with autism spectrum disorder (ASD), within Intensive Behavioral Intervention (IBI). Experiment 1 examined the relationship between scores on the commonly used Vineland Adaptive Behavior Scales Second Edition (VABS-II) (Sparrow, Cicchetto, & Balla, 2005) and scores on the PEAK Direct Training (PEAK-DT) (Dixon, 2014a) and PEAK Generalization (PEAK-G) (Dixon, 2014b) program assessments to examine additional psychometric properties suggesting the potential utility for use within IBI services. Experiment 2 examined the extent to which the PEAK manual (Dixon, 2014b) or additional staff training increased PEAK discrete trial training (DTT) procedural integrity of staff providing IBI to children diagnosed with ASD. Experiment 3 examined the effects of PEAK-G curriculum and instruction on the advanced language skills of children with ASD receiving IBI services. Results suggest that PEAK may be a valid assessment tool and effective intervention guide for use in IBI. Also, the manual and other effective staff training procedures (e.g., feedback, behavioral skills training) effectively enhance PEAK-G DTT procedural integrity. Lastly, the set of experiments in the current paper contributes to the dissemination of empirically based, behavior-analytic research that contributes to practical assessments and advanced interventions for children diagnosed with ASD. Specifically, PEAK-G enhances the language repertoires of children diagnosed with ASD through direct contingencies and programming for generalization across generalization gradients.
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Wiggins, Scott. "PEAK Relational Training System for Adults with Autism and Developmental Disabilities: Correlations with Vineland and VB-MAPP Assessments." OpenSIUC, 2015. https://opensiuc.lib.siu.edu/theses/1709.
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During the past decade, the prevalence of any developmental disability has increased from 12.84% to 15.04% (Boyle et al., 2011). In particular, the current rate of autism spectrum disorder (ASD) is estimated to effect 1 in every 68 children, 1 in 42 boys and 1 in 189 girls (Interagency Autism Coordinating Committee & US Department of Health and Human Services, 2012). Given that the prevalence of autism and other related disorders continues to increase, the number of children diagnosed with ASD who will become adolescents and adults over the next few years is considerable. More intensive evaluations and services are needed to address this aging population. A multiple probe design was used in the current study to demonstrate the effectiveness of the PEAK Relational Training System (PEAK; Dixon, 2014) in development of language and cognition in adults with autism. Additionally, this study evaluated if generalized behavior change occurred for participants following the implementation of the PEAK Direct Training assessment. This study will measure the effectiveness of the PEAK Relational Training System by comparing assessment scores from the Vineland Adaptive Behavior Scale-II (Sparrow, Cicchetti, & Balla, 2005) and the Verbal Behavior Milestones Assessment and Placement Program (VB-MAPP; Sundberg, 2008). Results revealed that verbal repertoires and adaptive functioning levels for participants increased following the implementation of programs from the PEAK Direct Training Assessment. Generalizes behavior change was achieved for all three participants through the acquisition of new untrained skills. Overall, this study provides empirical support for the PEAK Relational Training System in the development of language and cognition for adults with autism.
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Kondombo-Traoré, Fatimata. "L'utilisation des indices de développement de l'échelle de Vineland entre l'enfant autiste et ses parents : entre évaluation et remaillage des liens." Thesis, Normandie, 2020. http://www.theses.fr/2020NORMR086.
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Nous rendons compte ici d’une expérience de notre clinique institutionnelle avec des enfants souffrant de troubles du spectre de l’autisme en hôpital de jour. Notre objectif princeps est de trouver un accompagnement psychologique en nous appuyant sur l’évaluation par la VABS (Vineland Adaptive Behavior Scales) qui soit en adéquation avec les préoccupations des parents et des soignants, ce afin de les accompagner au mieux dans une démarche compréhensive des effets des troubles sur l’enfant et sur ses liens. Nous avons recueilli grâce à la double passation de l’échelle auprès des parents et des soignants référents leurs représentations sur les troubles de l’enfant, mais aussi sur ses compétences et ses ressources potentielles en émergence. Nous illustrons comment la VABS joue un rôle de médiation sur le suivi institutionnel de six jeunes dont deux filles et quatre garçons atteints de troubles du spectre de l’autisme. Les résultats obtenus portent sur l’observation et l’analyse de seize protocoles qui mettent en évidence des possibilités d’évolution de notre pratique clinique selon une approche intégrative et plurielle de la prise en charge institutionnelle et, en particulier, dans l’accompagnement des parents d’enfants atteints de troubles du spectre autistique. De plus nous présentons une expérience de clinique groupale où nous rendons compte aussi des résultats obtenus auprès de sept participants composés de parents et de familles d’accueil s’occupant quotidiennement d’enfants avec un TSAThe institutional practice in day hospital for children diagnosed with autism spectrum disorders is discussed here. The main objective focuses on a psychological intervention based on the rating with the VABS (Vineland Adaptive Behavior Scales) that takes into account the issues of both parents and caregivers to lead them to a better understanding of the impact of symptoms on the child and on the relationships. Double assessment of the scale on parents and on caregivers was conducted to collect their representations on the child disorder as well as their representations on his skills and his emerging potential. The function of the VABS on the mediation of the institutional follow-up of a six young people, including two girls and four boys, affected with autism spectrum disorders is illustrated. Results, which are based on the observation and analysis of sixteen protocols, point out the benefits of changing our clinical practice to a plural and integrative institutional approach, especially while tackling the assistance of parents confronted to autism spectrum disorders. Furthermore, outcomes on a group clinical experience, with seven participants composed of parents and foster families caring daily of children with ASDs, are also presented
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Garman, Jamie M. S. "Parental Expectations of the Future Functional Outcomes of Children Diagnosed with 22q11.2 Deletion Syndrome." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1491307765709204.
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Deang, Erelin. "An evaluation of derived relational responding, reasoning, and complex language: finding a correlation between the Vineland Adaptive Behavior Scale-II and PEAK Relational Training System – Transformation Module PA." OpenSIUC, 2018. https://opensiuc.lib.siu.edu/theses/2424.
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Many adults diagnosed with a developmental disability over the age of 20 have received inadequate care in the past due to the basic techniques, lack of funding, and minimal support when they were younger. Today, these adults are now receiving adequate care with behavioral support plans incorporating personal goals that they would like to achieve. Different assessments like Vineland Adaptive Behavior Scales have been utilized for children diagnosed with a disability measures a variety of skill sets one may have under the repertoire. These assessments could mold a curriculum to improve on the skills a child may lack. Even though these assessments are geared for children with developmental disabilities, they still could be utilized to assess adaptive skills especially with a focus on more complex reasoning and language amongst adults with disabilities. The present study measures the relationship between one’s adaptive skills with their complex thinking and reasoning. The assessments that were completed was the Vineland Adaptive Behavior Scales, 2nd Edition (VABS-II) for adaptive skills and Promoting the Emergence of Advanced Knowledge Relational Training System – Transformation Module Pre-Assessment (PEAK-T PA) for complex thinking and reasoning. The results indicated a significant correlation between not only one’s adaptive skills and their complex thinking (r = 0.53, p < 0.05), but also, between their expressive (r = 0.5, p < 0.05), receptive (r = 0.46, p < 0.05), and overall communication skills (r = 0.53, p < 0.05). This study extends the research on bridging the gap between derived relations and complex thinking.
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Reed, Mark Dobson. "The Role of Popular Mythology and Popular Culture in Post-war America, as represented by four novels - The Floating Opera and The End of the Road, by John Barth, White Noise, by Don DeLillo, and Vineland, by Thomas Pynchon." Thesis, The University of Sydney, 2004. http://hdl.handle.net/2123/627.
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The four novels - The Floating Opera, The End of the Road, White Noise, and Vineland - are representative of the cultural shift away from traditional moral concepts after World War II. Popular culture has increasingly become the guiding force for the continuation of American society, and in Don DeLillo�s White Noise, popular culture and its creation of myth (according to the author�s representation of America) has become embedded in the system and life of contemporary America. John Barth�s novel The End of the Road and its predecessor The Floating Opera are important in any discussion of the role of popular culture and popular mythology in post-war America. They both appear to signal an end to sincere intellectual thought or debate, and the notion of imposing a rational moral world upon the social landscape surrounding the individual. The Floating Opera explores the common tendency of society to avoid difficult intellectual struggles, and the central character and first-person narrator ultimately realises that questions about the nature of existence are of no objective value. In The End of the Road the character Jacob Horner adopts a superficial reflection of pre-existing rules and social conventions. Together these novels reflect much of what is at present understood as the postmodern aesthetic, and are indicative of many of the changes in America that were about to occur. The Floating Opera was published in 1956 and The End of the Road was published in 1958, but they are still highly relevant beyond the period in which they were written. White Noise (1984) portrays a system founded on the Hollywood mythology, and the superficial reflection of pre-existing rules and social conventions found in The End of the Road. The novel revolves around the experiences of the narrator, Jack Gladney, a university lecturer who teaches Hitler studies at Blacksmith College, and his wife Babette. The course which he teaches on Hitler is influenced by Hollywood myth, and the novel portrays a consumer-based society that has lost much of the firm moral basis which traditional religious concepts formerly supplied. The role of television, Hollywood, and the idea of simulation are all explored throughout the novel and are important forces in any examination of post-war American society. Finally, in Vineland (1990) the social upheavals which occurred during the late �60s and early �70s are explored from the perspective of the 1980s. The novel refers to a vast array of images and icons from popular culture, and the brief youth rebellion, in the late �60s, which failed to inspire any final social revolution. The result of this failed social revolution is a landscape of popular culture in modern America, where Godzilla leaves footprints in Japan and popular mythology from television or pulp novels coincides with everyday life. There are references in typical Pynchonesque fashion to those who must necessarily be orchestrating these social and cultural alterations, but they, as specific individuals, remain anonymous or hidden from the scope of the author (although, as in White Noise, there are deliberate references to the CIA and other agencies or departments within the U.S. Federal Government). Vineland is important, therefore, both as an account of the social changes which occurred in America between the late �60s and �80s, and the increasing role of popular culture in America. These four novels form the basis of an exploration of the role of popular mythology and popular culture in post-war America. They form a clear progression, and allow a detailed analysis of the social and cultural changes which contemporary America has undergone since the end of World War II.
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Reed, Mark Dobson. "The Role of Popular Mythology and Popular Culture in Post-war America, as represented by four novels - The Floating Opera and The End of the Road, by John Barth, White Noise, by Don DeLillo, and Vineland, by Thomas Pynchon." University of Sydney. English, 2004. http://hdl.handle.net/2123/627.
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The four novels - The Floating Opera, The End of the Road, White Noise, and Vineland - are representative of the cultural shift away from traditional moral concepts after World War II. Popular culture has increasingly become the guiding force for the continuation of American society, and in Don DeLillo�s White Noise, popular culture and its creation of myth (according to the author�s representation of America) has become embedded in the system and life of contemporary America. John Barth�s novel The End of the Road and its predecessor The Floating Opera are important in any discussion of the role of popular culture and popular mythology in post-war America. They both appear to signal an end to sincere intellectual thought or debate, and the notion of imposing a rational moral world upon the social landscape surrounding the individual. The Floating Opera explores the common tendency of society to avoid difficult intellectual struggles, and the central character and first-person narrator ultimately realises that questions about the nature of existence are of no objective value. In The End of the Road the character Jacob Horner adopts a superficial reflection of pre-existing rules and social conventions. Together these novels reflect much of what is at present understood as the postmodern aesthetic, and are indicative of many of the changes in America that were about to occur. The Floating Opera was published in 1956 and The End of the Road was published in 1958, but they are still highly relevant beyond the period in which they were written. White Noise (1984) portrays a system founded on the Hollywood mythology, and the superficial reflection of pre-existing rules and social conventions found in The End of the Road. The novel revolves around the experiences of the narrator, Jack Gladney, a university lecturer who teaches Hitler studies at Blacksmith College, and his wife Babette. The course which he teaches on Hitler is influenced by Hollywood myth, and the novel portrays a consumer-based society that has lost much of the firm moral basis which traditional religious concepts formerly supplied. The role of television, Hollywood, and the idea of simulation are all explored throughout the novel and are important forces in any examination of post-war American society. Finally, in Vineland (1990) the social upheavals which occurred during the late �60s and early �70s are explored from the perspective of the 1980s. The novel refers to a vast array of images and icons from popular culture, and the brief youth rebellion, in the late �60s, which failed to inspire any final social revolution. The result of this failed social revolution is a landscape of popular culture in modern America, where Godzilla leaves footprints in Japan and popular mythology from television or pulp novels coincides with everyday life. There are references in typical Pynchonesque fashion to those who must necessarily be orchestrating these social and cultural alterations, but they, as specific individuals, remain anonymous or hidden from the scope of the author (although, as in White Noise, there are deliberate references to the CIA and other agencies or departments within the U.S. Federal Government). Vineland is important, therefore, both as an account of the social changes which occurred in America between the late �60s and �80s, and the increasing role of popular culture in America. These four novels form the basis of an exploration of the role of popular mythology and popular culture in post-war America. They form a clear progression, and allow a detailed analysis of the social and cultural changes which contemporary America has undergone since the end of World War II.
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Sabra, Wael. "Microaerophilic production of alginate by Azotobacter vinelandii Mikroaerophile Alginatproduktion mit Azotobacter vinelandii /." [S.l. : s.n.], 1999. http://deposit.ddb.de/cgi-bin/dokserv?idn=956360513.
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Maia, Mauricio Silva. "Plasmids of Azotobacter vinelandii." Thesis, North Texas State University, 1986. https://digital.library.unt.edu/ark:/67531/metadc798298/.
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Nineteen laboratory strains of Azotobacter vinelandii and two organisms of the same species isolated from water samples were screened for the presence of plasmid deoxyribonucleic acid (DNA). Three laboratory strains and both organisms isolated from water samples contained one plasmid each. The migration distances of the plasmids in agarose gel electrophoresis were different molecular weights. The plasmids were cured by SDS or ethidium bromide treatment of the cultures.
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Chao, Ying L. (Ying Liang). "Ultrastructure of Azotobacter vinelandii." Thesis, North Texas State University, 1993. https://digital.library.unt.edu/ark:/67531/metadc798461/.
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The purpose of this research was to reveal the morphological and cytological characteristics of Azotobacter vinelandii cells cultured in dialyzed soil medium. Culture samples taken at two, four, eight, sixteen and thirty-two days were prepared and examined with the electron microscope. Comparisons of the morphology of Azotobacter vinelandii grown in dialyzed soil medium with those grown in Burk's nitrogen-free, chemically-defined medium were done.
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Brivonese, Anne Caterina. "Alginate biosynthesis in Azotobacter vinelandii." Thesis, University of Edinburgh, 1985. http://hdl.handle.net/1842/16946.
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Shen, Joan. "Roles of MoFe protein [alpha]-274-histidine, [alpha]-276-tyrosine and [alpha]-277-arginine residues in Azotobacter vinelandii nitrogenase catalysis /." This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06062008-162850/.
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Dalland, Marianne. "Transport av fenyl-lipid i Azotobacter vinelandii." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for bioteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-20997.
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Ved lav næringstilgang kan Azotobacter vinelandii gå inn i et cystestadium, hvor en del av fosfolipidene i yttermembranen erstattes med alkylresorcinoler og alkylpyroner. Gener involvert i syntese av alkylresorcinol og alkylpyron har tidligere blitt identifisert, og lokalisert i operonet arsABCD. Like oppstrøms for dette operonet ligger tre hypotetiske gener, Avin_29510, Avin_29500 og Avin_29490. Tidligere studier har vist at disse genene uttrykkes samtidig som arsABCD. Funksjonen av Avin_29510, Avin_29500 og Avin_29490 ble studert i denne oppgaven, genene fikk henholdsvis navnene arsF, arsD og arsH. arsF, arsG og arsH ble isolert fra A.vinelandii (villtype) ved PCR, og inaktivert ved å klone tetracyclinresistens-genene tetA og tetR inn i genene. Tre muterte stammer av A.vinelandii ble konstruert, hvor villtype-genet ble erstattet med henholdsvis inaktivert arsF, arsG og arsH. Dette ble utført ved homolog rekombinasjon. Cystestadium ble indusert i de tre mutant-stammene, før uttrykk av alkylresorcinol kunne undersøkes ved en fargereaksjon. Det kunne ikke detekteres alkylresorcinol i cystemembranen til mutantene. Da tidligere studier har vist at verken tetA eller tetR fører med seg polare effekter av betydning, ble det konkludert med at både arsF, arsG og arsH er essensielle for uttrykk av alkylresorcinol. Ved en bioinformatisk undersøkelse hvor de hypotetiske genene blant annet ble sekvenssammenstilt mot gener i andre organismer, ble det vist at arsF koder for en ATP-bindene komponent i en ABC-transportør. Det ble også vist at ArsG har likheter med permease-proteiner i ABC-transportsystem, og at ArsH muligens også er del av en ABC-transportør. For samtlige av de undersøkte genene ble det funnet homologe gener involvert i eksport av lipoprotein. De samlede resultatene fører med seg sterke indikasjoner på at arsF, arsG og arsH er involvert i eksport av alkylresorkinol ved cystedannelse. For å kunne verifisere at utslått arsF, arsG og arsH er årsaken til den observerte endringen i alkylresorcinol-produksjon hos muterte cyster, ble det dannet transposonplasmider med villtype-gen under kontroll av en Pm-promoter. Disse kan senere benyttes til å komplementere mutantene. Komplementeringsarbeidet ble ikke ferdigstilt i dette studiet grunnet tidsmangel.
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Gresholt, Ole Andreas. "Produksjon og transport av alkylresorcinol i Azotobacter vinelandii." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for bioteknologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-27117.
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A. vinelandii er kjent for sin evne til å danne cyster ved mangel på en tilstrekkelig næringskilde. Under cystedannelsen blir mange av fosfolipidene i yttermembranen erstattet med alkylresorcinoler og alkylpyroner. Et system tilstrekkelig for syntese av disse er blitt funnet å være kodet av operonet arsABCD. Nedstrøms for dette operonet finnes flere hypotetiske gener, hvorav 5 av dem blir sett nærmere på i dette prosjektet. Disse er Avin_29510 (arsF), Avin_29500 (arsG), Avin_29490 (arsH), Avin_29460 (gly), Avin_29450 (mal). arsFGH er tenkt å være involvert i dannelsen av en ABC-transportør med evne til å transportere alkylresorcinol gjennom cellemembranen. Avin_29450 (mal) er tenkt å kode for et enzym kalt malonyl-CoA-transferase, enzymet katalyserer en reaksjon med malonylCoA som er essensiell for biosyntesen av alkylresorcinol. Avin_29460 (gly) er tenkt å kode for enzymet glykosylase som kan være involvert i produksjonen av alkylresorcinol i A. vinelandii. Dette baseres på at noe av alkylresorcionolene produsert i A. vinelandii har blitt vist til å inneholde en galaktose gruppe.Strategien for å undersøke funksjonen av samtlige av disse gene var å konstruere separate delesjonsmutanter for hvert gen og analysere hvordan dette påvirket A. vinelandii sin evne til å produsere eller transportere alkylresorcinol. Delesjonsmutanter og transposonvektorer til arsFGH var allerede produsert ved starten av dette prosjektet. Disse mutantene skulle i dette prosjektet verifiseres ved komplementering. Pm-promotoren brukt til å utrykke villtype genet i transposonvektorerne til arsFGH blir under dette prosjekt vist til og ikke fungere etter hensikt ved cystedannelse og tilsatts av m-toluat. Det blir derfor konstruert nye transposonvektorer for disse gene med villtype-gen under kontroll av palgD. For deteksjon av alkylresorcinol ble det i dette prosjektet etablert en metode ved reaksjon med en løsning inneholdende Fast Blue B. Saltet Fast blue B og 5-n-alkylresorcinol / Orcinol(standard) reagerer med hverandre i nærvær av aceton og danner et rødt presipitat. Fargeomslag som følger av dette kan måles spektofotometrisk ved 520nm.Under dette prosjektet ble det konstruert en delesjonsmutant for Avin_29460 (gly) og funnet tegn på at dette genet kan påvirke vekstraten til A. vinelandii. Et knockout-plasmid for Avin_29450 (mal) ble også ferdigstilt, men en delesjonsmutant ble funnet til å være vanskelig å produsere. Dette kan tyde på at genet er viktig for veksten av A. vinelandii til den grad at villtypen tar over kulturen. Avin_29460 (gly) og Avin_29450 (mal) ble klonet som første trinn i prosessen med å lage vektor for å utrykke disse i A. vinelandii mutanter.
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Wilson, Mark Steven Michael. "Mutagenesis of nifE and nifN from Azotobacter vinelandii." Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/43071.
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The products of nifE and nifN from Azotobacter vinelandii, which
are involved in the biosynthesis of the iron-molybdenum cofactor (FeMo-co)
co) from nitrogenase, have been analyzed using a variety of mutagenic techniques.
NifE was the object of several site-specific, amino acid
substitutions that were designed to elicit information regarding metal cluster ligands, subunit-subunit interactions, and the proposed transfer
of FeMo-co.from a nifEN-products complex to the apo-MoFe protein. A
model of metal cluster binding; regions within the nifEN-products is
discussed insofar as it relates to the rationale for the targeting of
particular amino acids for-substitution.
A translational fusion between nifN and lacZ was constructed and
used to study the regulation of nifEN. This gene fusion was regulated
in the same manner as wild type nifN and produced a fusion protein which was enzymatically active with respect to substrates of β-galactosidase.
Results from mutant strains which carry lesions in nifH or nifA in
addition to the nifN::lacZ fusion are presented and discussed.Master of Science
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Comaratta, Leonard M. "Characterization of an altered MoFe protein from a nifV- strain from Azotobacter vinelandii." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36177.
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The site of substrate binding and reduction for the nitrogenase complex is located on the iron molybdenum cofactor (FeMo-co) which is contained within the a-subunit of the molybdenum iron protein. FeMo co consists of a metal sulfur core composed of an FeS cluster bridged by three inorganic sulfides to a MoFeS cluster. An organic acid, homocitrate, is coordinated to the Mo atom through its 2-carboxy and 2-hydroxy groups. Homocitrate is formed by the condensation of acetyl-CoA and a-ketoglutarate, which is catalyzed by a homocitrate synthase encoded by nifV. By deleting the nifV gene from Azotobacter vinelandii we were able to study the role of homocitrate in nitrogenase catalysis. A poly-histidine tail was incorporated into the C-termini of the a-subunit permitting isolation of the homocitrateless MoFe protein by using metal affinity chromatography. We have found that the addition of a poly-histidine tag does not alter the catalytic behavior of the native enzyme. In NifV- strains of Klebsiella pneumoniae, citrate has been found to replace homocitrate as the organic constituent of FeMo-co. We have found no evidence this is so in A. vinelandii. Gas chromatography mass spectrophotometry studies indicate little or no organic acids are associated with FeMo-co. We examined the catalytic properties of the NifV- MoFe protein In the mutant, H2 evolution is inhibited by the addition of CO, unlike in the wild type. We have found that the NifV- MoFe protein from A. vinelandii is able to catalyze the reduction of acetylene to both ethylene and ethane.Master of Science
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Silva, Adriana Navarro da [UNESP]. "Produção otimizada de alginato e plástico biodegradável (poli-hidroxibutirato) por Azotobacter vinelandii." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/88400.
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O alginato é um polissacarídeo normalmente extraído de paredes celulares de algas marrons utilizado nas indústrias de alimentos, farmacêuticas e biotecnológicas. A produção é concentrada no cultivo de algas marinhas marrons, mas várias bactérias do gênero Pseudomonas e Azotobacter produzem alginato. A estrutura química dos alginatos produzidos por algas é similar aos sintetizados pela A. vinelandii. Esta bactéria também produz polímeros intracelulares como o poli-hidroxibutirato (PHB), conhecido como bioplástico. Neste trabalho estudou-se a produção simultânea do alginato e PHB pela A. vinelandii utilizando sacarose, glicose e melaço de cana-de-açúcar como fontes de carbono, além de diferentes parâmetros de fermentação em agitador orbital rotatório. Os valores ótimos para a produção destes compostos foram determinados pela metodologia de superfície de resposta (MSR). O 1º experimento realizado para as três fontes de carbono foi um planejamento fatorial fracionado 26-2 (variáveis independentes: concentração da fonte de carbono; concentração de acetato de amônio; concentração de citrato de amônio e ferro (III); pH; temperatura de incubação e tempo de incubação). O 2º experimento baseou-se nos valores ótimos de produção de PHB para cada fonte de carbono e resultou em um planejamento fatorial completo 33-0 (variáveis independentes: concentração da fonte de carbono; temperatura de incubação e tempo de incubação). Verificou-se que a maior produtividade de PHB (100 mg/g de célula/h) utilizando o melaço de cana-de-açúcar ocorreu no tempo de incubação de aproximadamente 10 h, a 60,0ºC e nas concentrações de sólidos solúveis entre 14,0 - 25,0%. A glicose apresentou uma maior produtividade de PHB (60 mg/g de célula/h) no tempo de incubação de aproximadamente 10 h, entre 23,0-26,0ºC e concentração de glicose...
The alginate is a polysaccharide extracted from cell walls of brown seaweed used in the industries of food, pharmaceutical and biotechnology. The production is concentrated in the brown seaweed cultivation, but several bacteria, Pseudomonas and Azotobacter genus, produce alginate. The chemical structure of alginate produced by algae is similar to those synthesized by A. vinelandii. This bacterium also produces intracellular polymers such as polyhydroxybutyrate (PHB), known as bioplastic. In this work the simultaneous alginate and PHB production by A. vinelandii using sucrose, glucose and sugar cane molasses as carbon source, and different fermentation parameters in orbital shaker was studied. The optimum values for the production of these compounds were determined by the response surface methodology (RSM). The 1st experiment conducted for the three carbon sources was a fractionated factorial design 26-2 (independent variables: the carbon source concentration; ammonium acetate concentration; ammonium citrate and iron (III) concentration; pH; temperature and incubation time). The 2nd experiment was based on optimum values for the production of PHB for each carbon source and resulted in a full factorial design 33-0 (independent variables: the carbon source concentration; temperature and incubation time). The highest PHB yield (100 mg/g cell/h) using sugar cane molasses as a carbon source was found in 10 h at 60.0 ºC and solids soluble concentrations between 14.0 and 25.0%. The glucose showed the highest PHB yield (60 mg/g cell/h) in approximately 10 h, at temperature between 23.0 – 26.0 ºC and glucose concentration between 48.0 and 62.0 g/L. The sucrose, showed the highest PHB yield (45 mg/g cell/h) in approximately 18 h, 60.0 ºC and sucrose concentration of 10.0 g/L. For the alginate productivity using the glucose was observed that the yield was more... (Complete abstract click electronic access below)
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Mouncey, Nigel J. "Characterisation of molybdenum transport and processing in Azotobacter vinelandii." Thesis, University of Sussex, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262526.
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Lee, Yick-Shun. "Endogenous Nucleotide Pools in Growing Cells of Azotobacter Vinelandii." Thesis, North Texas State University, 1987. https://digital.library.unt.edu/ark:/67531/metadc500771/.
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The objective of this investigation was to examine the changes in the nucleotide pools of Azotobacter vinelandii during the growth cycle. Endogenous ribonucleotides were extracted from A. vinelandii using trichloroacetic acid (TCA; 12% w/v). The 5' mono-, di- and triphosphates of adenine, guanine, uracil and cytosine were separated and quantified by anion-exchange high performance liquid chromatography. Results indicated that the adenylate energy charge of A. vinelandii paralleled the growth rate during exponential phase and that it declined rapidly as the stationary phase was reached. In addition, the amount of each nucleotide in A. vinelandii tended to increase in the logarithmic phase and decrease in the stationary phase in a similar manner to the energy charge.
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Dong, Hanqing. "Structural and functional analysis of metalloproteins in Azotobacter vinelandii." Diss., Mississippi State : Mississippi State University, 2007. http://sun.library.msstate.edu/ETD-db/theses/available/etd-11062007-105105/.
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Kim, ChulHwan. "Azotobacter vinelandii nitrogenase : role of the MoFe protein [alpha]-subunit histidine-195 residue in catalysis /." This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06062008-164937/.
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Brewin, Brett. "Mechanism of ammonium excretion in NifL mutants of Azotobacter vinelandii." Thesis, University of East Anglia, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323244.
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Jradi, Hoda A. "The morphology of Azotobacter vinelandii grown in dialyzed soil medium." Thesis, University of North Texas, 1992. https://digital.library.unt.edu/ark:/67531/metadc798045/.
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This research describes the changes in cell morphology of Azotobacter vinelandii cells cultured in dialyzed soil medium. This particular culture medium was assumed to provide the bacteria with an environment similar to their natural habitat, the soil.
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Jack, Richard F. "Characterization and site-directed mutagenesis of NifU from Azotobacter vinelandii." Diss., This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-10042006-143858/.
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Jünemann, Susanne. "The catalytic mechanism of the cytochrome bd terminal oxidase complex." Thesis, King's College London (University of London), 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309173.
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Orišková, Sofia. "Inkorporace mikrobiálních buněk do hydrogelových nosičů." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2020. http://www.nusl.cz/ntk/nusl-433584.
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The presented diploma thesis focuses on the use of plant growth promoting bacteria as an ecological alternative to conventional fertilizers. The incorporation of bacterial cells into hydrogel carriers is already a well-studied topic, but due to its disadvantages it has not yet found wider application in agriculture. This work offers a novel concept of encapsulating bacteria by gelation directly from the culture. This is achieved by crosslinking the bacterial alginate produced by the model microorganism Azotobacter vinelandii. Since this process was not described before, first its optimization was needed. Alginate production was determined gravimetrically, and its parameters were further characterized using available analytical methods – infrared spectroscopy to monitor structural parameters (monomer composition and the extent of acetylation), dynamic light scattering to characterize the size distribution and AF4-MALS-dRI to obtain the molecular weight. Bacterial PHB production was also investigated using gas chromatography and infrared spectroscopy. The second part of the work is focused on the optimization of the gelling process using bacterial alginate from the culture and CaCl2 as a crosslinking agent. Rheological experiments were used as a tool in understanding the viscoelastic properties of the prepared gels. Gelation was demonstrated within the first day after inoculation. Maximum production of alginate (1,9 ± 0,3) g/l was reached on the fourth day after inoculation. It was found that the addition of 5 g/l of calcium carbonate promotes the production of alginate. Nevertheless, further addition of CaCO3 (30 g/l) showed adverse effects on the molecular weight and is therefore not recommended. Production of PHB was confirmed by both FTIR and GC measurements, with a maximum yield of (23 ± 3) % CDW. Rheological testing confirmed that the product of the crosslinking was a gel. It was found that the crosslinker concentration plays an important role at time 0 min of the gelation, forming a denser network in the structure and causing higher rigidity. Using the highest studied concentration of CaCl2, the critical strain reached values of (5,0 ± 0,7) %. Finally, the incorporation of bacterial cells into the hydrogel was confirmed using fluorescence microscope.
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Gogu, Sudhir Reddy. "Resistance and Morphology of Azotobacter Vinelandii Grown on Dialyzed Soil Agar." Thesis, North Texas State University, 1987. https://digital.library.unt.edu/ark:/67531/metadc798103/.
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The objectives of this research were to identify the form of Azotobacter as it exists in situ in the soil; to compare its resistance to that of laboratory grown cysts typical of those described in the literature; and to compare its resistance to that of cells grown on dialyzed soil agar. In addition, the morphology of the cells grown on dialyzed soil agar was examined by light and electron microscopy and then compared to the cysts grown on n-butanol Burk's medium. Dipicolinic acid and oxygen uptake rate were measured in cysts and on cells grown on dialyzed soil agar in order to determine whether the cells grown on dialyzed soil agar were endospores or other dormant form and also to measure the respiratory quotient in these cells.
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O'Carroll, Ina Puleri. "Assembly of Iron-Sulfur Clusters In Vivo." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/26289.
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Iron-sulfur [Fe-S] clusters are protein cofactors that facilitate various life-sustaining biological processes. Their in vivo assembly is accomplished by three different systems known to date. These are: the NIF system which provides [Fe-S] clusters for nitrogenase and other nitrogen-fixing proteins, the SUF system which is induced during conditions of oxidative stress and iron starvation in E. coli, and the ISC system which serves as the housekeeping assembly apparatus. The latter is the focus of this dissertation and includes the proteins IscR, IscS, IscU, IscA, HscB, HscA, Fdx, and IscX. IscU is purified in its cluster-less (apo) form, but can serve as a scaffold to assemble [Fe-S] clusters in vitro in the presence of excess iron and sulfide. To test the scaffold hypothesis and gain insight into the events that occur during [Fe-S] cluster assembly and delivery, we developed two methods that allow the isolation of IscU and other ISC proteins in vivo. In the first method, Azotobacter vinelandii IscU is isolated from its native host, whereas in the second, it is isolated recombinantly from E. coli using a vector that allows expression of the entire isc operon. We found that IscU exists in vivo in two forms: apo-IscU and [2Fe-2S]2+ cluster-loaded IscU which are believed to be conformationally distinct. Both transient and stable IscU-IscS complexes were identified, indicating that the two proteins interact in vivo in a manner that involves their association and dissociation. The [2Fe-2S]2+-IscU species was present as a single entity, whereas significant amounts of apo-IscU were found associated with IscS, suggesting that IscU-IscS dissociation is triggered by the completion of [2Fe-2S] clusters. Both apo and [2Fe-2S]2+-IscU were predominantly monomeric whereas IscU-IscS complexes were determined to have an α2β2 composition. IscU was purified in the absence of the chaperones HscA and HscB and was also shown to accommodate a [2Fe-2S]2+ cluster similar to the one bound to IscU isolated from wild type cells. The findings suggest that [2Fe-2S]2+-IscU exists in one conformation in vivo and that any conformational changes on IscU are exerted after [2Fe-2S] cluster formation. In silico studies showed that a flexible loop containing the conserved LPPVK motif, which is responsible for interactions with HscA, may facilitate cluster exposure to either mediate its delivery to acceptor proteins or participation in the construction of [4Fe-4S] clusters. Experiments with NfuA, a protein similar to the C-terminal domain of NifU, demonstrated that NfuA and similar proteins might serve as [Fe-S] cluster carriers to accomplish the efficient delivery of nascent cofactors to the various recipient proteins.Ph. D.
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Wang, Baomin. "Studies on the Regulation of the Assimilatory Nitrate Reductase Operon in Azotobacter vinelandii." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/195085.
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Azotobacter vinelandii is a free-living diazotroph. This bacterium fixes atmospheric nitrogen in different environments using three genetically distinct nitrogenases. A. vinelandii is also capable of utilizing nitrate and nitrite from the environment. Nitrate is reduced sequentially into nitrite and ammonia. The assimilatory nitrate reductase and nitrite reductase are encoded by the nasAB operon. Previous genetic studies identified a number of factors that influence nasAB expression. However, the molecular mechanisms controlling the expression of nasAB are unclear.The current study was initiated to characterize the region preceding the nasAB operon which was previously implicated in its regulation and to further study the molecular mechanisms of nasAB regulation. The results confirm that nasAB is subject to multiple layers of regulation. The operon is under the control of an NtrC-dependent promoter; nitrate/nitrite induction occurs at the post-transcriptional level via antitermination within the nasAB leader region; and nitrate/nitrite induction is mediated by NasS/NasT, a sensor-antiterminator two-component regulatory system.Together, these data suggest a model for the regulation of the assimilatory nitrate reductase operon in A. vinelandii.
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Schemberg, Jörg. "Biochemische Charakterisierung und Untersuchungen der Röntgenstruktur am Molybdänspeicherprotein aus Azotobacter vinelandii." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=983027374.
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Haugsnes, Margit Dagsdatter. "Karakterisering av gener som påvirker biosyntesen av alginat i Azotobacter vinelandii." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for bioteknologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18367.
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For å undersøke faktorer som innvirker på alginat-produksjonen til Azotobacter vinelandii har det blitt laget et mutant-bibliotek med stammen A. vinelandii ATCC 12518 som utgangspunkt. Etter screeningsforsøk med henblikk på vekst- og alginatproduksjon av mutant-stammene ble det plukket ut et antall opp- og nedmutanter som ble undersøkt videre for å bestemme hvilke gener som var muterte og deres funksjon i forbindelse med alginatbiosyntesen i A. vinelandii.Denne oppgaven startet med å undersøke 17 nedmutanter fra screening-undersøkelse av biblioteket. Det ble satt opp vekstforsøk med alginatessay i to runder.Da utvalgte mutanter ble sekvensert for å finne ut hvilke gener som hadde transposoninsersjon viste det seg at transposon-vektoren pCAM140 var tilstede i alle stammene. Denne delen av oppgaven ble avbrutt og strategien for oppgaven noe endret. Det ble plukket ut to stammer som var kjente ned-mutanter fra screeningsforsøk og som allerede var sekvensert. Stammene 20A6 og 21T3C ble undersøk for å bekrefte fenotype og forsøkt komplementert for å bekrefte/undersøke videre funksjon av gener. 20A6 har mutasjon i genet for sucA (Avin_29770) som sannsynligvis kotranskriberes med sucB og lpdA. Denne stammen viste seg å ha både vill-type alleler og mutant-alleler tilstede, selv etter langvarig forsøk på seleksjon for mutant-alleler. Stammen 21C3T har mutasjon i Avin_13880, et gen som koder for en transkripsjonsregulator av IclR-klasse. Komplementering gav ikke stammene forventet alginat-produksjon tilbake. Det ble også gjort bioinfomatiske undersøkelser og litteraturstudier for å forsøke å klarlegge hvilken funksjon de ovennevnte genene har i alginatsyntesen i A. vinelandii.
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Setterquist, Robert Alan. "Site-directed mutagenesis of the nitrogenase MoFe protein from Azotobacter vinelandii." Thesis, Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/50091.
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A model describing the potential amino acid ligands to the four 4Fe-4S centers (P-clusters) within the Azotobacter vinelandii nitrogenase MoFe protein is presented. Based on interspecies and intersubunit amino acid comparisons of the α- and ß-subunits of the MoFe protein, and the FeMoco biosynthetic proteins, NifE and NifN, four conserved residues (Cys62, His83, Cys88, Cys154 all proposed P-cluster ligands) within the α- subunit were targeted for site-directed mutagencsis studies. In order to define a range of acceptable substitutions, 35 specific site-mutants have been constructed, each with a different amino acid replacement at one of the four targeted positions. Previous studies indicated that these residues were important for MoFe activity, and may act as metallocenter ligands. Unusual redox and spectroscopic properties of the Fe-S centers suggest the involvement of ligands other than the four typical cysteines, though extrusion requirements indicate that some thiol ligands are likely. Surprisingly, mutants with an Asp, Gly, Thr, or Ser substituted for Cys88 are still capable of diazotrophic growth (Nif+), though whole cell and crude extract acetylene reduction activity is lowered. Several substitutions (Cys, Asp, Phe, Asn, Met, Tyr, Leu) are tolerated at the His83 position, these Nif+ mutant strains also have varying acetylene reduction rates and growth rates. All mutants with substitutions at positions 62, 154, resulted in complete loss of diazotrophic growth. The results could be interpreted by the following explanations:
1) Our proposed model for the P-cluster ligation within the MoFe protein is incorrect.
2) Some substitutions permit P-cluster rearrangement to a semi-functional state.
3) Either, P-clusters are not absolutely essential for diazotrophic growth, or the enzyme can function with a reduced number of these metal centers.Master of Science
incomplete_metadata
39
Silva, Adriana Navarro da [UNESP]. "Substratos alternativos para a produção de poli-hidroxibutirato e alginato por Azotobacter vinelandii." Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/100889.
Full textAbstract:
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Atualmente a destinação do lixo é uma das grandes preocupações da organização urbana e os problemas ambientais causados pela produção e acúmulo de materiais plásticos de origem petroquímica têm incentivado muitos países a realizarem estudos de gerenciamento do volume de lixo sólido, incluindo a diminuição de resíduos plásticos por meio do desenvolvimento de bioplásticos. Os bioplásticos possuem propriedades semelhantes às dos plásticos convencionais e apresentam a vantagem de serem facilmente degradados pela ação de microrganismos no ambiente, podendo citar como exemplo os poli-hidroxialcanoatos (PHA), dentre eles o poli-hidroxibutirato (PHB). Estes polímeros podem representar até 80% da massa seca total da célula, tendo como característica principal a biodegradabilidade em solos e a biocompatibilidade com o tecido animal. Entre os microrganismos produtores de PHAs, a bactéria Azotobacter vinelandii pode acumular grandes quantidades de PHB intracelular com a vantagem de utilizar durante seu crescimento uma ampla variedade de açúcares como os encontrados em melaço de cana-de-açúcar, beterraba e xarope de milho, além de resíduos da suinocultura, agroindustriais, etc. Além do PHB, a bactéria A. vinelandii é capaz de produzir alginato, composto muito empregado na área de análogos de frutas ou produtos tipo imitação como: fatias de pimentão para recheios de azeitonas, imitação de anéis de cebola, imitações de caviar, carne, pescados, produtos marinhos, etc. Tendo em vista que os principais fatores limitantes para a produção de biopolímeros estão associados, principalmente, com os custos dos substratos e ao fato de que muitos microrganismos são patogênicos dificultando a sua aceitação pela comunidade em geral, este trabalho teve como objetivo utilizar...
Currently, the waste disposal is a major concern of urban organization and the environmental problems caused by production and accumulation of petrochemical plastics have encouraged many countries to management studies of the solid waste volume, including the waste plastics reduction through the bioplastics development. Bioplastics have similar properties to conventional plastics and the advantage of being easily degraded by the microorganisms action in the environment, for example, poly-hydroxyalcanoatos (PHA), including poly-hydroxybutyrate (PHB). These polymers can represent up to 80% of total dry mass of the cell, having as main feature the biodegradability in soil and the biocompatibility with animal tissue. Among the microorganisms producing PHAs, the bacterium Azotobacter vinelandii can accumulate large amounts of intracellular PHB with the advantage that they grow a wide sugars variety like those found in molasses cane sugar, beet sugar and corn syrup, and swine waste, agribusiness, etc.. Besides the PHB, the bacterium A. vinelandii is able to produce alginate, a very useful compound in the similar area of type of fruit and imitation as sliced peppers for stuffing olives, onion rings imitation, caviar, meat, fish and marine products imitation, etc.. Given that the main limiting factors for the biopolymers production are mainly associated with the substrates costs and the fact that many microorganisms are pathogenic hindering its acceptance by the community in general, this study aimed to use the pollutant by-products environment (residual oil frying, glycerin, cassava wastewater – “manipueira”, vinasse and wastewater industry carbonated beverages or soft drinks) as a substrate for the poly-hydroxybutyrate and alginate production by non-pathogenic bacterium Azotobacter vinelandii. Fermentations... (Complete abstract click electronic access below)
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Raulfs, Estella Callie. "Isolation of in vivo intermediates in iron sulfur cluster biogenesis." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/26949.
Full textAbstract:
Iron-sulfur clusters are simple inorganic cofactors that are ubiquitous in living systems. The assembly of iron sulfur clusters is an essential process and must be carefully controlled in order to limit the release of toxic free iron or sulfide. Thus far there are three known protein systems for iron sulfur cluster assembly including the nif, suf, and isc systems. The nif system makes iron-sulfur clusters for nitrogenase production, while both the suf and isc systems provide iron-sulfur clusters for general cellular use. In Azotobacter vinelandii the isc operon contains eight genes which are transcribed together as a single operon: iscR iscS iscU iscA hscB hscA fdx iscX. The two central isc players include IscS, a cysteine desulfurase, and IscU the proposed site of iron-sulfur cluster assembly.
Using A. vinelandii as a model organism, we have sought to better understand the mechanism of in vivo isc cluster assembly. In order test the scaffold hypothesis, we constructed strains that allowed for quick and rapid isolation of IscU. The purification of IscU with a bound [2Fe-2S] cluster strongly supports the model that IscU serves as the site of cluster synthesis in vivo. Additionally, using this same genetic system we isolated an IscU39DA variant with an oxygen stable bound [2Fe-2S] cluster. The IscU39DA scaffold came in tight α₂β₂ complex with IscS and was not separated by high salt, size exclusion, or reducing conditions. On the other hand, wild-type IscU also associated with IscS in a α₂β₂ complex, but readily dissociated upon increased salt concentration. The tight association of IscU39DA and IscS was found to occur regardless of the presence of a bound [Fe-S] cluster. We conclude that the IscU Asp-39 residue is essential for mediating the dissociation of IscU and IscS.
In addition to studying IscS and IscU, we were interested to further understand how the isc system is regulated in response to external factors. Previous work has demonstrated that IscR controls expression of the isc operon in Escherichia coli. When IscR is holo this protein represses isc expression, while in its apo-form it allows isc expression. In A. vinelandii we found that ∆iscR strains exhibit in a 5 – 7 fold elevation of isc expression. Additionally, ∆iscR strains reveal a small growth phenotype on plates, and a tendency to form spontaneous suppressor mutations allowing reversion to wild-type growth. Loss of apo-IscR function was found to cause a more severe effect on growth than the loss of holo-IscR function, suggesting IscR has cellular roles in addition to the regulation of the isc operon.Ph. D.
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Choi, Munhyeong. "The possibility of branch conformation in Azotobacter vinelandii chromosomal DNA carrying multiple gene copies and its folded state in the cell." Thesis, University of North Texas, 1991. https://digital.library.unt.edu/ark:/67531/metadc798271/.
Full textAbstract:
Chromosomal DNA of A. vinelandii thought to carry multiple gene copies was examined in efforts to visualize its chromosomal structure using electron microscopy. The chromosomal DNA of A. vinelandii may have multiple circular genomic units carrying multiple copies of genes. Three possible branch construction schemes and their replication modes are postulated in this study.
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Melušová, Soňa. "Studium produkce polyhydroxybutyrátu u bakterií." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2009. http://www.nusl.cz/ntk/nusl-216477.
Full textAbstract:
Presented work is focused on study of polyhydroxybutyrate production in bacteria. In theoretical part short characterization of PHB was given and the most common representative of wide group of polyhydroxyalkanoates (PHA) were described. Then, production of PHB and copolymer P(HB-co-HV) in selected bacterial strains was experimentally proven. First, PHB production in Bacillus megaterium using synthetic medium was studied. The PHB content in cells was increased during cultivation under limiting conditions, despite low growth. Addition of ethanol into production media resulted in increased PHB synthesis as well as biomass production (21 % PHB of 1,8 g/l biomass). Further, BM medium containing 8 g/l glucose was tested. PHB production was more than 1 g/l at significant growth increase when compared with synthetic medium. The bacteria B.megaterium showed, except glucose, ability to utilize maltose and xylose. Another cultivations were tested with bacterial strain Azotobacter vinelandii, which is capable of copolymer P(HB-co-HV) synthesis. Maximal growth and copolymer content was reached on Burk's medium with 30 g/l of glucose. Addition of peroxide to growth medium influenced P(HB-co-HV) synthesis to 46 % of 2,6 g/l biomass. Bacteria A.vinelandii showed the best growth on maltose, even compared with glucose (54 % copolymer of biomass content). Finally, PHB production on industrial waste product – whey was monitored. Using Plackett-Burman design for statistical media optimization, the whey content was modified. B.megaterium grown on adjusted whey reached 0,5 g/l PHB, 32 % of cell's content.
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Sharpe, Anne. "Characterization of a gene required for catecholate siderophore biosynthesis in Azotobacter vinelandii." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0004/MQ40109.pdf.
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Burger, Eva-Maria Michaela [Verfasser], and Oliver [Akademischer Betreuer] Einsle. "Structural characterisation of nitrogen fixation by the enzyme nitrogenase of Azotobacter vinelandii." Freiburg : Universität, 2015. http://d-nb.info/1119805805/34.
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Silva, Adriana Navarro da. "Produção otimizada de alginato e plástico biodegradável (poli-hidroxibutirato) por Azotobacter vinelandii /." São José do Rio Preto : [s.n.], 2009. http://hdl.handle.net/11449/88400.
Full textAbstract:
Orientador: Crispin Humberto Garcia CruzBanca: Alexandre Rodrigo Coelho
Banca: Vanildo Luiz Del Bianchi
Resumo: O alginato é um polissacarídeo normalmente extraído de paredes celulares de algas marrons utilizado nas indústrias de alimentos, farmacêuticas e biotecnológicas. A produção é concentrada no cultivo de algas marinhas marrons, mas várias bactérias do gênero Pseudomonas e Azotobacter produzem alginato. A estrutura química dos alginatos produzidos por algas é similar aos sintetizados pela A. vinelandii. Esta bactéria também produz polímeros intracelulares como o poli-hidroxibutirato (PHB), conhecido como bioplástico. Neste trabalho estudou-se a produção simultânea do alginato e PHB pela A. vinelandii utilizando sacarose, glicose e melaço de cana-de-açúcar como fontes de carbono, além de diferentes parâmetros de fermentação em agitador orbital rotatório. Os valores ótimos para a produção destes compostos foram determinados pela metodologia de superfície de resposta (MSR). O 1º experimento realizado para as três fontes de carbono foi um planejamento fatorial fracionado 26-2 (variáveis independentes: concentração da fonte de carbono; concentração de acetato de amônio; concentração de citrato de amônio e ferro (III); pH; temperatura de incubação e tempo de incubação). O 2º experimento baseou-se nos valores ótimos de produção de PHB para cada fonte de carbono e resultou em um planejamento fatorial completo 33-0 (variáveis independentes: concentração da fonte de carbono; temperatura de incubação e tempo de incubação). Verificou-se que a maior produtividade de PHB (100 mg/g de célula/h) utilizando o melaço de cana-de-açúcar ocorreu no tempo de incubação de aproximadamente 10 h, a 60,0ºC e nas concentrações de sólidos solúveis entre 14,0 - 25,0%. A glicose apresentou uma maior produtividade de PHB (60 mg/g de célula/h) no tempo de incubação de aproximadamente 10 h, entre 23,0-26,0ºC e concentração de glicose... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The alginate is a polysaccharide extracted from cell walls of brown seaweed used in the industries of food, pharmaceutical and biotechnology. The production is concentrated in the brown seaweed cultivation, but several bacteria, Pseudomonas and Azotobacter genus, produce alginate. The chemical structure of alginate produced by algae is similar to those synthesized by A. vinelandii. This bacterium also produces intracellular polymers such as polyhydroxybutyrate (PHB), known as bioplastic. In this work the simultaneous alginate and PHB production by A. vinelandii using sucrose, glucose and sugar cane molasses as carbon source, and different fermentation parameters in orbital shaker was studied. The optimum values for the production of these compounds were determined by the response surface methodology (RSM). The 1st experiment conducted for the three carbon sources was a fractionated factorial design 26-2 (independent variables: the carbon source concentration; ammonium acetate concentration; ammonium citrate and iron (III) concentration; pH; temperature and incubation time). The 2nd experiment was based on optimum values for the production of PHB for each carbon source and resulted in a full factorial design 33-0 (independent variables: the carbon source concentration; temperature and incubation time). The highest PHB yield (100 mg/g cell/h) using sugar cane molasses as a carbon source was found in 10 h at 60.0 ºC and solids soluble concentrations between 14.0 and 25.0%. The glucose showed the highest PHB yield (60 mg/g cell/h) in approximately 10 h, at temperature between 23.0 - 26.0 ºC and glucose concentration between 48.0 and 62.0 g/L. The sucrose, showed the highest PHB yield (45 mg/g cell/h) in approximately 18 h, 60.0 ºC and sucrose concentration of 10.0 g/L. For the alginate productivity using the glucose was observed that the yield was more... (Complete abstract click electronic access below)
Mestre
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Cartini, F. "UNRAVELLING FUNCTIONAL INTERACTIONS OF THE RHODANESE-LIKE PROTEIN RhdA OF AZOTOBACTER VINELANDII." Doctoral thesis, Università degli Studi di Milano, 2008. http://hdl.handle.net/2434/59570.
Full textAbstract:
The subjects of the present investigation were A. vinelandii RhdA and E.coli SseA, that in the rhodanese-domain panorama represent two prototypes of tandem-domain rhodanese proteins. They belong to two different subfamilies: TSTs and MSTs and their active-site motifs, (CRXGX[R/T]) and (CG[S/T]GVT) respectively, are considered important in driving substrate recognition.
In this work, multiple approaches were exploited with the aim of elucidating physiological role(s) of RhdA. We first focused on searching a possible metabolic pathway involving RhdA. Starting from the experimental evidence of direct sulfane sulfur transfer from E. coli IscS to RhdA (Forlani et al., 2005), we analyzed whether RhdA could function as sulfane sulfur acceptor of A. vinelandii cysteine desulfurases taking in account the importance of the trafficking of the persulfide in the biosynthetic pathways (Meuller 2006).
Secondly, RhdA and SseA biological role(s) were investigated in vivo, taking advantage of the availability of an A. vinelandii mutant strain lacking rhdA gene (Colnaghi et al, 1996) and of an E. coli mutant strain lacking sseA gene (Celestini 2001). Different growth conditions in presence or in absence of oxidative agents have been evaluated, starting from the evidence that the RhdA null mutant MV474 was more prone than the wild-type strain UW136 to oxidative stress (Cereda et al., 2007).
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Silva, Adriana Navarro da. "Substratos alternativos para a produção de poli-hidroxibutirato e alginato por Azotobacter vinelandii /." São José do Rio Preto : [s.n.], 2012. http://hdl.handle.net/11449/100889.
Full textAbstract:
Orientador: Crispin Humberto Garcia-CruzBanca: Eleni Gomes
Banca: José Roberto Ernandes
Banca: Mário Antônio Alves da Cunha
Banca: Vanildo Luiz Del Bianchi
Resumo: Atualmente a destinação do lixo é uma das grandes preocupações da organização urbana e os problemas ambientais causados pela produção e acúmulo de materiais plásticos de origem petroquímica têm incentivado muitos países a realizarem estudos de gerenciamento do volume de lixo sólido, incluindo a diminuição de resíduos plásticos por meio do desenvolvimento de bioplásticos. Os bioplásticos possuem propriedades semelhantes às dos plásticos convencionais e apresentam a vantagem de serem facilmente degradados pela ação de microrganismos no ambiente, podendo citar como exemplo os poli-hidroxialcanoatos (PHA), dentre eles o poli-hidroxibutirato (PHB). Estes polímeros podem representar até 80% da massa seca total da célula, tendo como característica principal a biodegradabilidade em solos e a biocompatibilidade com o tecido animal. Entre os microrganismos produtores de PHAs, a bactéria Azotobacter vinelandii pode acumular grandes quantidades de PHB intracelular com a vantagem de utilizar durante seu crescimento uma ampla variedade de açúcares como os encontrados em melaço de cana-de-açúcar, beterraba e xarope de milho, além de resíduos da suinocultura, agroindustriais, etc. Além do PHB, a bactéria A. vinelandii é capaz de produzir alginato, composto muito empregado na área de análogos de frutas ou produtos tipo imitação como: fatias de pimentão para recheios de azeitonas, imitação de anéis de cebola, imitações de caviar, carne, pescados, produtos marinhos, etc. Tendo em vista que os principais fatores limitantes para a produção de biopolímeros estão associados, principalmente, com os custos dos substratos e ao fato de que muitos microrganismos são patogênicos dificultando a sua aceitação pela comunidade em geral, este trabalho teve como objetivo utilizar... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Currently, the waste disposal is a major concern of urban organization and the environmental problems caused by production and accumulation of petrochemical plastics have encouraged many countries to management studies of the solid waste volume, including the waste plastics reduction through the bioplastics development. Bioplastics have similar properties to conventional plastics and the advantage of being easily degraded by the microorganisms action in the environment, for example, poly-hydroxyalcanoatos (PHA), including poly-hydroxybutyrate (PHB). These polymers can represent up to 80% of total dry mass of the cell, having as main feature the biodegradability in soil and the biocompatibility with animal tissue. Among the microorganisms producing PHAs, the bacterium Azotobacter vinelandii can accumulate large amounts of intracellular PHB with the advantage that they grow a wide sugars variety like those found in molasses cane sugar, beet sugar and corn syrup, and swine waste, agribusiness, etc.. Besides the PHB, the bacterium A. vinelandii is able to produce alginate, a very useful compound in the similar area of type of fruit and imitation as sliced peppers for stuffing olives, onion rings imitation, caviar, meat, fish and marine products imitation, etc.. Given that the main limiting factors for the biopolymers production are mainly associated with the substrates costs and the fact that many microorganisms are pathogenic hindering its acceptance by the community in general, this study aimed to use the pollutant by-products environment (residual oil frying, glycerin, cassava wastewater - "manipueira", vinasse and wastewater industry carbonated beverages or soft drinks) as a substrate for the poly-hydroxybutyrate and alginate production by non-pathogenic bacterium Azotobacter vinelandii. Fermentations... (Complete abstract click electronic access below)
Doutor
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Johnson, Deborah Cumaraswamy. "Controlled Expression and Functional Analysis of the Iron-Sulfur Cluster Biosynthetic Machinery in Azotobacter vinelandii." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/27755.
Full textAbstract:
A system was developed for the controlled expression of genes in Azotobacter vinelandii by using genomic fusions to the sucrose catabolic regulon. This system was used for the functional analysis of the A. vinelandii isc genes, whose products are involved in the maturation of [Fe-S] proteins. For this analysis the scrX gene, contained within the sucrose catabolic regulon, was replaced by the A. vinelandii iscS, iscU, iscA, hscB, hscA, fdx, iscX gene cluster, resulting in duplicate genomic copies of these genes, one whose expression is directed by the normal isc regulatory elements (Pisc) and the other whose expression is directed by the scrX promoter (PscrX). Functional analysis of [Fe-S] protein maturation components was achieved by placing a mutation within a particular Pisc-controlled gene with subsequent repression of the corresponding PscrX-controlled component by growth on glucose as the carbon source.
This experimental strategy was used to show that IscS, IscU, HscBA and Fdx are essential in A. vinelandii and that their depletion results in a deficiency in the maturation of aconitase, an enzyme that requires a [4Fe-4S] cluster for its catalytic activity. Depletion of IscA results in null growth only when cells are cultured under conditions of elevated oxygen, marking the first null phenotype associated with the loss of a bacterial IscA-type protein. Furthermore, the null growth phenotype of cells depleted for HscBA could be partially reversed by culturing cells under conditions of low oxygen. These results are interpreted to indicate that HscBA and IscA could have functions related to the protection or repair of the primary IscS/IscU machinery when grown under aerobic conditions. Conserved amino acid residues within IscS, IscU, and IscA that are essential for their respective functions and/or display a partial or complete dominant-negative growth phenotype were also identified using this system. Inactivation of the IscR repressor protein resulted in a slow growth phenotype that could be specifically attributed to the elevated expression of an intact [Fe-S] cluster biosynthetic system.
This system was also used to investigate the extent to which the two [Fe-S] biosynthetic systems in A. vinelandii, Nif and Isc, can perform overlapping functions. Under normal laboratory growth conditions, no cross-talk between the two systems could be detected. However, elevated expression of Isc components as a consequence of inactivation of the IscR repressor protein results in a modest ability of the Isc [Fe-S] protein maturation components to replace the function of Nif-specific [Fe-S] protein maturation components. Similarly, when expressed at very high levels the Nif-specific [Fe-S] protein maturation components could functionally replace the Isc components. Oxygen levels were also found to affect the ability of the Nif and Isc systems to perform common functions. Nevertheless, the lack of significant reciprocal cross-talk between the Nif and Isc systems when they are produced only at levels necessary to satisfy their respective physiological functions, indicates a high level of target specificity with respect to [Fe-S] protein maturation.Ph. D.
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Shivaji, Sangeetha. "Functional analysis of a modC homolog in the Azotobacter vinelandii nif-gene cluster." Master's thesis, Mississippi State : Mississippi State University, 2008. http://library.msstate.edu/etd/show.asp?etd=etd-11052008-165140.
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Jepson, Brian John Nicholas. "Characterisation of anfa, the transcriptional activator of the FE-nitrogenase from Aztobacter vinelandii." Thesis, University of East Anglia, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251439.
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