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Os profissionais da área da saúde que atuam no serviço de atendimento pré-hospitalar podem estar sujeitos a fatores de risco cardiovasculares em razão do estilo de vida adotado e das características do trabalho. O objetivo principal do estudo foi avaliar a influência do plantão de 24 horas sobre a pressão arterial e os fatores de risco para afecções cardiovasculares nesses profissionais. Casuística e Método: Estudo transversal com 154 profissionais (90 enfermeiros, 41 médicos, 23 auxiliares de enfermagem) que atuavam no serviço de atendimento pré-hospitalar: Grupo de Atendimento Médico de Urgência (GRAU-193), Serviço Móvel de Urgência (SAMU-192) e Samu-Vale do Ribeira. Realizou-se medida da pressão arterial casual com aparelho automático validado e considerou-se hipertenso pressão 140/90mmHg e/ou uso de anti-hipertensivos. Procedeu-se a Monitorização Ambulatorial da Pressão Arterial (MAPA), durante o plantão no pré-hospitalar e em dia usual de atividade. Foram analisados o índice de massa corpórea (IMC), a circunferência abdominal (CA), a glicemia, o perfil lipídico e a proteína C reativa. O risco cardiovascular foi calculado pelo Escore de Risco de Framingham (ERF) e avaliada a presença da Síndrome Metabólica. Foram utilizados os instrumentos: Índice de Qualidade de Sono de Pittsburg, Self Report Questionnaire, Inventário de Depressão de Beck, Escala de Estresse no Trabalho e Malasch Burnout Inventory. O nível de significância adotado foi p<0,05, utilizou-se análise univariada e regressão logística para as variáveis significativas. Resultados: As características dos participantes foram: idade 40,9±7,8 anos. Sedentarismo 64,9%, CA alterado 70,2% e IMC sobrepeso/obeso de 65,6%. Alteração de glicose em 11%, colesterol elevado em 11%, LDL-c alto 7,8%, HDL-c alto 11% e triglicérides em 16,2%, proteína C reativa 40,3% nos quartis mais altos. A prevalência da hipertensão arterial pela medida casual no pré-hospitalar foi 33,1% e em dia usual de atividade 13,6%. Na MAPA de 24h no pré-hospitalar 29,3%, dia usual de atividade 22,6%; MAPA da vigília no pré-hospitalar 26,6%, dia usual de atividade 18,5%; MAPA no sono pré-hospitalar 63,0%, dia usual de atividade 42,5%. Houve diferenças significativas nos níveis pressóricos pré-hospitalares em relação ao dia usual de atividade para medida casual sistólica e diastólica (124,9±15,1mmHg/79,0±10,8 mmHg vs. 122,1±14,5mmHg/76,7±10,5mmHg) e na MAPA no período de sono, para a pressão diastólica (110,5±11,5mmHg/72,6±9,5mmHg vs. 111,8±10,8mmHg/67,6±7,9 mmHg). Os fatores associados à hipertensão foram a pela medida casual: HDL-c > 40 mg/dL (Odds Ratio (OR) 0,257; intervalo de confiança (IC) 95%: 0,0810,813) e ERF > 10% (OD: 23,159; IC 95%: 2,029264,378). b) pela MAPA: no período de 24 horas: sexo masculino (OR: 2,717; IC 95%: 1,206-6,122); trabalhar cansado raramente/nunca (OR: 0,197; IC 95%: 0,061-0,638) e às vezes (OR: 0,174; IC 95%: 0,050-0,614); glicemia > 100 mg/dL (OR: 9,983; IC 95%: 1,560-63,881). Para MAPA da vigília: sexo masculino (OR: 3,245; IC 95%: 1,385-7,606); trabalhar cansado raramente/nunca (OR: 0,142; IC 95%: 0,042-0,481); e às vezes (OR: 0,163; IC 95%: 0,045-0,590); glicemia > 100 mg/dL (OR:11,1809; IC 95%: 1,632-76,60) e IMC > 25kg/m2 (OR: 1,101; IC 95%: 1,006-1,206). Para MAPA do sono: IMC > 25kg/m2 (OR: 1,119; IC 95%: 1,021-1,226) e presença de sono diurno (OR: 0,140; IC 95%: 0,065-0,300). O Escore de Risco de Framingham foi médio/alto em 10,6%; Síndrome Metabólica presente em 28,6%, má qualidade de sono em 41,6%, transtornos mentais comuns em 16,2%, depressão em 7,8%, média de estresse no trabalho em 50,1% e Burnout em 29%. Conclusão: houve diferenças pressóricas durante o plantão no serviço pré-hospitalar em relação a um dia usual de atividade, e os profissionais estudados estavam expostos a fatores de risco modificáveis, sendo necessárias mudanças no estilo de vida / Professionals that work in pre-hospital assistance might be subject to the cardiovascular risk factors due to their adopted lifestyle and specific characteristics of their occupation. Casuistic and Method: Transversal study with 154 professionals (90 nurses, 41 physicians, 23 nurse auxiliaries) that work in prehospital: Grupo de Atendimento Médico de Urgência [Group of Emergency Medical Assistance] (GRAU-193), Serviço Móvel de Urgência [Emergency Rescue Service] (SAMU-192) and Samu-Vale do Ribeira. Measures were performed regarding casual blood pressure; it was considered arterial hypertensive pressure (HA) 140/90mmHg and/or use of antihypertensives. The Ambulatorial Monitoring of Blood Pressure (ABPM) was performed during the duty on prehospital and also on casual day of activities. The Body Mass Index (IMC), Abdominal Circumference (CA), glucose, lipids profile and C-reactive protein were analyzed. The cardiovascular risk was used Framingham Risk Score (ERF), Metabolic Syndrome were analyzed. The used tools were: Pittsburg Sleep Quality Index, Self Report Questionnaire, Beck Depression Inventory, Job Stress Scale and Malasch Burnout Inventory. Data were processed on SPSS System v.7.5. The level of significance adopted was p <0,05, univariate analysis was used and the logistic regression was performed for remarkable variables. Results: Age of 40,9 ± 7,8 years. Sedentary lifestyle 64,9%, CA altered 70,2% and IMC overweight/obese of 65,6%. Glucose alteration in 11%, elevated cholesterol in 11%, high LDL-c in 7,8%, high HDL-c in 11% and triglycerides in 16,2%, C-reactive protein in 40,3% on higher quartiles. The prevalence of prehospital HA: 33,1% and casual day of activities 13,6%. ABPM: 24h prehospital 29,3%, casual day of activities 22,6%; ABPM: daytime prehospital 26,6%, casual day of activities 18,5%; ABPM: nighttime prehospital 63,0%, casual day of activities 42,5%. There were significant differences on pressoric levels of prehospital in comparison with casual day of activities for casual measure of systolic and diastolic pressures (124,9±15,1 mmHg/79,0±10,8 mmHg vs. 122,1±14,5 mmHg; /76,7±10,5mmHg), and on ABPM of nighttime period for diastolic pressure (110,5 ± 11,5 mmHg/72,6±9,5 mmHg vs. 111,8±10,8 mmHg/67,6±7,9 mmHg). Factors related with casual HA: HDL-c > 40 mg/dL (Odds Ratio (OR) 0,257; confidence interval (IC) 95%: 0,0810,813) and ERF >10% (OD: 23,159; IC 95%: 2,029264,378). The HA measured by ABPM: on 24 hours period: male gender (OR: 2,717; IC 95%: 1,206-6,122); never/occasionally work tired (OR: 0,197; IC 95%: 0,061-0,638) and sometimes (OR: 0,174; IC 95%: 0,050-0,614); glucose > 100mg/dL (OR: 9,983; IC 95%: 1,560-63,881). For daytime: male gender (OR: 3,245; IC 95%: 1,385-7,606); never/occasionally work tired (OR: 0,142; IC 95%: 0,042-0,481); and sometimes (OR: 0,163; IC 95%: 0,045-0,590); glucose > 100mg/dL (OR: 11,1809; IC 95%: 1,632-76,60) and IMC > 25kg/m2 (OR: 1,101; IC 95%: 1,006-1,206). For nighttime period: IMC > 25kg/m2 (OR: 1,119; IC 95%: 1,021-1,226) and presence of somnolence during day (OR: 0,140; IC 95%: 0,065-0,300). Prevalence of Metabolic Syndrome: 28,6%; Framingham Risk Score: medium/high: 10,6%; poor quality of sleeping 41,6%, common mental disorders: 16,2%, depression: 7,8%, average job stress: 50,1% and Burnout 29%. It might be concluded: that there were pressoric differences during duty on prehospital in comparison with a casual day of activities, and that these professionals are exposed to the modifiable risk factor and need changes in their lifestyles.

Os profissionais da área da saúde que atuam no serviço de atendimento pré-hospitalar podem estar sujeitos a fatores de risco cardiovasculares em razão do estilo de vida adotado e das características do trabalho. O objetivo principal do estudo foi avaliar a influência do plantão de 24 horas sobre a pressão arterial e os fatores de risco para afecções cardiovasculares nesses profissionais. Casuística e Método: Estudo transversal com 154 profissionais (90 enfermeiros, 41 médicos, 23 auxiliares de enfermagem) que atuavam no serviço de atendimento pré-hospitalar: Grupo de Atendimento Médico de Urgência (GRAU-193), Serviço Móvel de Urgência (SAMU-192) e Samu-Vale do Ribeira. Realizou-se medida da pressão arterial casual com aparelho automático validado e considerou-se hipertenso pressão 140/90mmHg e/ou uso de anti-hipertensivos. Procedeu-se a Monitorização Ambulatorial da Pressão Arterial (MAPA), durante o plantão no pré-hospitalar e em dia usual de atividade. Foram analisados o índice de massa corpórea (IMC), a circunferência abdominal (CA), a glicemia, o perfil lipídico e a proteína C reativa. O risco cardiovascular foi calculado pelo Escore de Risco de Framingham (ERF) e avaliada a presença da Síndrome Metabólica. Foram utilizados os instrumentos: Índice de Qualidade de Sono de Pittsburg, Self Report Questionnaire, Inventário de Depressão de Beck, Escala de Estresse no Trabalho e Malasch Burnout Inventory. O nível de significância adotado foi p<0,05, utilizou-se análise univariada e regressão logística para as variáveis significativas. Resultados: As características dos participantes foram: idade 40,9±7,8 anos. Sedentarismo 64,9%, CA alterado 70,2% e IMC sobrepeso/obeso de 65,6%. Alteração de glicose em 11%, colesterol elevado em 11%, LDL-c alto 7,8%, HDL-c alto 11% e triglicérides em 16,2%, proteína C reativa 40,3% nos quartis mais altos. A prevalência da hipertensão arterial pela medida casual no pré-hospitalar foi 33,1% e em dia usual de atividade 13,6%. Na MAPA de 24h no pré-hospitalar 29,3%, dia usual de atividade 22,6%; MAPA da vigília no pré-hospitalar 26,6%, dia usual de atividade 18,5%; MAPA no sono pré-hospitalar 63,0%, dia usual de atividade 42,5%. Houve diferenças significativas nos níveis pressóricos pré-hospitalares em relação ao dia usual de atividade para medida casual sistólica e diastólica (124,9±15,1mmHg/79,0±10,8 mmHg vs. 122,1±14,5mmHg/76,7±10,5mmHg) e na MAPA no período de sono, para a pressão diastólica (110,5±11,5mmHg/72,6±9,5mmHg vs. 111,8±10,8mmHg/67,6±7,9 mmHg). Os fatores associados à hipertensão foram a pela medida casual: HDL-c > 40 mg/dL (Odds Ratio (OR) 0,257; intervalo de confiança (IC) 95%: 0,0810,813) e ERF > 10% (OD: 23,159; IC 95%: 2,029264,378). b) pela MAPA: no período de 24 horas: sexo masculino (OR: 2,717; IC 95%: 1,206-6,122); trabalhar cansado raramente/nunca (OR: 0,197; IC 95%: 0,061-0,638) e às vezes (OR: 0,174; IC 95%: 0,050-0,614); glicemia > 100 mg/dL (OR: 9,983; IC 95%: 1,560-63,881). Para MAPA da vigília: sexo masculino (OR: 3,245; IC 95%: 1,385-7,606); trabalhar cansado raramente/nunca (OR: 0,142; IC 95%: 0,042-0,481); e às vezes (OR: 0,163; IC 95%: 0,045-0,590); glicemia > 100 mg/dL (OR:11,1809; IC 95%: 1,632-76,60) e IMC > 25kg/m2 (OR: 1,101; IC 95%: 1,006-1,206). Para MAPA do sono: IMC > 25kg/m2 (OR: 1,119; IC 95%: 1,021-1,226) e presença de sono diurno (OR: 0,140; IC 95%: 0,065-0,300). O Escore de Risco de Framingham foi médio/alto em 10,6%; Síndrome Metabólica presente em 28,6%, má qualidade de sono em 41,6%, transtornos mentais comuns em 16,2%, depressão em 7,8%, média de estresse no trabalho em 50,1% e Burnout em 29%. Conclusão: houve diferenças pressóricas durante o plantão no serviço pré-hospitalar em relação a um dia usual de atividade, e os profissionais estudados estavam expostos a fatores de risco modificáveis, sendo necessárias mudanças no estilo de vida / Professionals that work in pre-hospital assistance might be subject to the cardiovascular risk factors due to their adopted lifestyle and specific characteristics of their occupation. Casuistic and Method: Transversal study with 154 professionals (90 nurses, 41 physicians, 23 nurse auxiliaries) that work in prehospital: Grupo de Atendimento Médico de Urgência [Group of Emergency Medical Assistance] (GRAU-193), Serviço Móvel de Urgência [Emergency Rescue Service] (SAMU-192) and Samu-Vale do Ribeira. Measures were performed regarding casual blood pressure; it was considered arterial hypertensive pressure (HA) 140/90mmHg and/or use of antihypertensives. The Ambulatorial Monitoring of Blood Pressure (ABPM) was performed during the duty on prehospital and also on casual day of activities. The Body Mass Index (IMC), Abdominal Circumference (CA), glucose, lipids profile and C-reactive protein were analyzed. The cardiovascular risk was used Framingham Risk Score (ERF), Metabolic Syndrome were analyzed. The used tools were: Pittsburg Sleep Quality Index, Self Report Questionnaire, Beck Depression Inventory, Job Stress Scale and Malasch Burnout Inventory. Data were processed on SPSS System v.7.5. The level of significance adopted was p <0,05, univariate analysis was used and the logistic regression was performed for remarkable variables. Results: Age of 40,9 ± 7,8 years. Sedentary lifestyle 64,9%, CA altered 70,2% and IMC overweight/obese of 65,6%. Glucose alteration in 11%, elevated cholesterol in 11%, high LDL-c in 7,8%, high HDL-c in 11% and triglycerides in 16,2%, C-reactive protein in 40,3% on higher quartiles. The prevalence of prehospital HA: 33,1% and casual day of activities 13,6%. ABPM: 24h prehospital 29,3%, casual day of activities 22,6%; ABPM: daytime prehospital 26,6%, casual day of activities 18,5%; ABPM: nighttime prehospital 63,0%, casual day of activities 42,5%. There were significant differences on pressoric levels of prehospital in comparison with casual day of activities for casual measure of systolic and diastolic pressures (124,9±15,1 mmHg/79,0±10,8 mmHg vs. 122,1±14,5 mmHg; /76,7±10,5mmHg), and on ABPM of nighttime period for diastolic pressure (110,5 ± 11,5 mmHg/72,6±9,5 mmHg vs. 111,8±10,8 mmHg/67,6±7,9 mmHg). Factors related with casual HA: HDL-c > 40 mg/dL (Odds Ratio (OR) 0,257; confidence interval (IC) 95%: 0,0810,813) and ERF >10% (OD: 23,159; IC 95%: 2,029264,378). The HA measured by ABPM: on 24 hours period: male gender (OR: 2,717; IC 95%: 1,206-6,122); never/occasionally work tired (OR: 0,197; IC 95%: 0,061-0,638) and sometimes (OR: 0,174; IC 95%: 0,050-0,614); glucose > 100mg/dL (OR: 9,983; IC 95%: 1,560-63,881). For daytime: male gender (OR: 3,245; IC 95%: 1,385-7,606); never/occasionally work tired (OR: 0,142; IC 95%: 0,042-0,481); and sometimes (OR: 0,163; IC 95%: 0,045-0,590); glucose > 100mg/dL (OR: 11,1809; IC 95%: 1,632-76,60) and IMC > 25kg/m2 (OR: 1,101; IC 95%: 1,006-1,206). For nighttime period: IMC > 25kg/m2 (OR: 1,119; IC 95%: 1,021-1,226) and presence of somnolence during day (OR: 0,140; IC 95%: 0,065-0,300). Prevalence of Metabolic Syndrome: 28,6%; Framingham Risk Score: medium/high: 10,6%; poor quality of sleeping 41,6%, common mental disorders: 16,2%, depression: 7,8%, average job stress: 50,1% and Burnout 29%. It might be concluded: that there were pressoric differences during duty on prehospital in comparison with a casual day of activities, and that these professionals are exposed to the modifiable risk factor and need changes in their lifestyles.

In South Africa various financial institutions and independent vendors have developed residential property valuation models to estimate the current value of historically traded properties. A natural extension to these models has been to develop historical property price indices. In this dissertation, three of the four approaches to developing property price indices will be examined. Through back–testing and other statistical methods, the most accurate and robust approach will be determined. The four major approaches available are the mean valuation per suburb, the median valuation per suburb, the repeat sales approach and hedonic regression. The mean valuation per suburb approach can be biased because of outliers in property prices. However, outliers in property prices will not influence the median valuation per suburb approach, but in cases where property values in a suburb have a skewed distribution, the valuation amount could be distorted. Neither of the above mentioned shortcomings influences the repeat sales or the hedonic regression approach. To follow the hedonic regression approach, the characteristics of the property need to be known. In South Africa, however, the available property data lacks detailed characteristics of traded properties. This dissertation will therefore focus on the first three methods. The repeat sales approach measures the growth in property prices by applying a generalized linear model to properties that have traded more than once. This approach is only possible if there is a representative amount of repeat sales able to fit a model. The focus of this project will be on the repeat sales approach, but all three the approaches discussed will be analysed to prove that the repeat sales approach is the most accurate in developing a property price index for properties in South Africa. / Thesis (M.Sc. (Risk Analysis))--North-West University, Potchefstroom Campus, 2011.

In South Africa various financial institutions and independent vendors have developed residential property valuation models to estimate the current value of historically traded properties. A natural extension to these models has been to develop historical property price indices. In this dissertation, three of the four approaches to developing property price indices will be examined. Through back–testing and other statistical methods, the most accurate and robust approach will be determined. The four major approaches available are the mean valuation per suburb, the median valuation per suburb, the repeat sales approach and hedonic regression. The mean valuation per suburb approach can be biased because of outliers in property prices. However, outliers in property prices will not influence the median valuation per suburb approach, but in cases where property values in a suburb have a skewed distribution, the valuation amount could be distorted. Neither of the above mentioned shortcomings influences the repeat sales or the hedonic regression approach. To follow the hedonic regression approach, the characteristics of the property need to be known. In South Africa, however, the available property data lacks detailed characteristics of traded properties. This dissertation will therefore focus on the first three methods. The repeat sales approach measures the growth in property prices by applying a generalized linear model to properties that have traded more than once. This approach is only possible if there is a representative amount of repeat sales able to fit a model. The focus of this project will be on the repeat sales approach, but all three the approaches discussed will be analysed to prove that the repeat sales approach is the most accurate in developing a property price index for properties in South Africa. / Thesis (M.Sc. (Risk Analysis))--North-West University, Potchefstroom Campus, 2011.

Text in English / The aim of the current study was to explore the impact of the Educhange and Research Foundation (ERF) self-awareness programme on the participants’ reactions, experiences, and changes in opinion regarding their knowledge of concepts of self-awareness. This study constitutes an evaluation of a workshop presented by the ERF which is a Non-Governmental Organisation (NGO) aimed at generating solutions toward a better education for all learners through the application of Kirkpatrick’s model of evaluating education and training programmes. Kirkpatrick’s model follows the goal-based evaluation approach and is based on four levels of evaluation. These four levels are widely known as reaction, learning, behaviour, and results. Due to the feasibility of the research, only the reaction and learning evaluation levels were researched. The population identified for the study comprised 15 grade 9 to 11 secondary school learners from Soweto in South Africa which were encouraged to volunteer to take part in the study at their convenience. The sample consisted of all the learners who attended the self-awareness workshop, in effect making this a purposive, convenience sampling. The ERF Board were responsible for the sample selection for their scholarship programme. One of the minimum criteria of selection to take part in the programme was that the learner must have obtained 70% and stem from poor backgrounds. The relatively small sample size possesses the potential to limit the generalisation of the findings. A mixed method approach was employed for this research. Positivist paradigm is the epistemological stance adopted due to the social reality investigated. The sources of data consisted of pre- and post-evaluation questionnaires on self-awareness. The results were thematically and statistically analysed. Thematic analysis included familiarisation with the data and first finding meaning, and then identifying patterns of recurring meaning by generating initial codes and lastly generating themes that run through these meanings.Statistical analysis was conducted through comparison of the data before and after the workshop using chi-square. Objective self-awareness theory and the self-regulation theory were the theoretical framework that informed the current research study. The main finding from this study was that the programme was perceived to have raised positive subjective opinions and feelings of most of the participants, although one participant raised negative subjective opinions about the programme and made suggestions for improvement. After the workshop, the participants felt that they had gained a better understanding of the key concepts of self-awareness, although most items were found to be statistically insignificant. / Psychology / M.A. (Psychology)

The aim of the current study was to explore the impact of the Educhange and Research Foundation (ERF) self-awareness programme on the participants’ reactions, experiences, and changes in opinion regarding their knowledge of concepts of self-awareness. This study constitutes an evaluation of a workshop presented by the ERF which is a Non-Governmental Organisation (NGO) aimed at generating solutions toward a better education for all learners through the application of Kirkpatrick’s model of evaluating education and training programmes. Kirkpatrick’s model follows the goal-based evaluation approach and is based on four levels of evaluation. These four levels are widely known as reaction, learning, behaviour, and results. Due to the feasibility of the research, only the reaction and learning evaluation levels were researched. The population identified for the study comprised 15 grade 9 to 11 secondary school learners from Soweto in South Africa which were encouraged to volunteer to take part in the study at their convenience. The sample consisted of all the learners who attended the self-awareness workshop, in effect making this a purposive, convenience sampling. The ERF Board were responsible for the sample selection for their scholarship programme. One of the minimum criteria of selection to take part in the programme was that the learner must have obtained 70% and stem from poor backgrounds. The relatively small sample size possesses the potential to limit the generalisation of the findings. A mixed method approach was employed for this research. Positivist paradigm is the epistemological stance adopted due to the social reality investigated. The sources of data consisted of pre- and post-evaluation questionnaires on self-awareness. The results were thematically and statistically analysed. Thematic analysis included familiarisation with the data and first finding meaning, and then identifying patterns of recurring meaning by generating initial codes and lastly generating themes that run through these meanings.Statistical analysis was conducted through comparison of the data before and after the workshop using chi-square. Objective self-awareness theory and the self-regulation theory were the theoretical framework that informed the current research study. The main finding from this study was that the programme was perceived to have raised positive subjective opinions and feelings of most of the participants, although one participant raised negative subjective opinions about the programme and made suggestions for improvement. After the workshop, the participants felt that they had gained a better understanding of the key concepts of self-awareness, although most items were found to be statistically insignificant. / Psychology / M.A. (Psychology)

Les légumineuses sont connues pour leurs capacités à établir une relation symbiotique avec des bactéries du sol fixatrices de l'azote atmosphérique. Cette interaction aboutit à la formation d'un nouvel organe au niveau des racines, la nodosité, au sein duquel le symbiote convertit l'azote atmosphérique (N2) en ammoniac, qui peut être directement consommé par les plantes. A l’intérieur de cette nodosité, la concentration en oxygène (O2) est maintenue à un très faible niveau car la réaction de réduction du N2 par l’enzyme bactérienne nitrogénase est inhibée par des traces d’oxygène. Un mécanisme de perception directe de l'O2 impliquant des membres de la famille des facteurs de transcription « Ethylene Responsive Factors » (ERFs) du groupe VII a récemment été découvert chez Arabidopsis thaliana. Ces facteurs de transcription (FT) possèdent une extrémité N-terminale caractéristique avec un résidu de cystéine à la seconde position. Dans des conditions normales d'O2, les FT sont conduit à la dégradation suivant une voie spécifique du protéasome. En condition de stress hypoxique, les TFs sont stabilisés et peuvent activer l’expression des gènes de réponse à l'hypoxie. Il a été démontré que la présence d’O2 et de NO était nécessaire pour déstabiliser ces protéines, et qu'une réduction de la disponibilité de l'un ou l'autre des gaz est suffisante pour protéger le résidu cystéine N-terminale de l'oxydation. L’objectif de cette thèse a été d'étudier le rôle de la famille ERF-VII dans la perception et l'adaptation au manque d'O2 chez M. truncatula. Des travaux ont aussi été menés pour déterminer l’importance du NO dans le fonctionnement en microoxie de la nodosité. Quatre gènes codant pour des facteurs de transcription de la famille ERF-VII ont été identifiés dans le génome de M. truncatula. La caractérisation de cette famille au niveau transcriptionnel a révélé que seul MtERF-B2.2 était induit par le stress hypoxique et au cours du développement des nodosités. Les trois autres, MtERF-B1.1, MtERF-B1.11 et MtERF-B2.3, sont constitutivement exprimés dans les feuilles, les racines et les nodosités. Pour étudier la stabilité de la protéine MtERF-B2.1, l’orthologue de RAP2.12 principal ERF-VII décrit dans la perception de l’O2 chez Arabidopsis, en fonction de la disponibilité de O2/NO, nous avons réalisé une protéine de fusion entre l’extrémité N-terminale de notre protéine et la protéine rapporteur luciférase. Les résultats obtenus sur des protoplastes d'Arabidopsis montrent l’implication la partie N-terminale de MtERF-B2.1 dans la régulation de la stabilité de la protéine, mais en contradiction avec les résultats obtenus en plantes composites de M. truncatula. La fonction de MtERF-B2.1 et MtERF-B2.11 a également été étudiée dans le cadre de la réponse au stress hypoxique et au cours du processus de nodulation en utilisant une stratégie d'interférence ARN. Des racines transgéniques dérégulées sur l’expression de MtERF-B2.1 et MtERF-B2.11 ont montré un défaut d’activation de plusieurs gènes de réponses à l'hypoxie tels que l’alcool déshydrogénase (ADH1) ou la pyruvate décarboxylase (PDC1). Ces racines transgéniques ARNi-MtERF-B2.1/B2.11 sont également affectées dans l'interaction symbiotique avec une réduction significative de la capacité de nodulation et de l'activité de fixation de l'azote dans les nodules matures. En conclusion, ces travaux révèlent que le mécanisme de détection d'O2 est médié par les ERF-VII dans les nodosités de M. truncatula et que ce mécanisme, associé aux cibles moléculaires régulées en aval, participe au développement de cet organe et au maintien de la capacité de fixatrice de celui-ci. De plus, les résultats indiquent que MtERF-B2.1/B2.11 sont des régulateurs positifs du métabolisme anaérobie et que les gènes associés au cycle hémoglobine-NO sont susceptibles d'activer d'autres voies de génération d'ATP. / Legume crops are known for their capacities to establish a symbiotic relationship with nitrogen fixing soil bacteria. This mutualism culminates in the formation of a new plant organ, the root nodule, in which the symbiont converts atmospheric nitrogen (N2) into ammonia, which can be directly consumed by plants. In nodules, bacterial nitrogenase enzyme is inhibited by traces of oxygen (O2) so different mechanisms maintain this organ at low O2 level. At the same time, nodules need to maintain a high ATP level to support the nitrogenase activity, which is highly energy demanding. Thus, a balance between a tight protection from O2 and an efficient energy production, referred as the “O2 paradox” of N2-fixing legume nodules, has to be reached. In Arabidopsis thaliana, a direct oxygen sensing mechanism has recently been discovered involving members of the ethylene responsive factors (ERFs) group VII. These transcription factors (TFs) possess a characteristic N-terminal amino acid with a cysteine residue at the second position that, under normal O2 conditions, leads to protein degradation following a specific pathway called the N-end rule pathway. Furthermore, it was shown that both O2 and nitric oxide (NO) are required to destabilize the ERFs VII and that a reduction in the availability of either gas is sufficient to stabilize these proteins. Therefore, the goal of this thesis was to investigated the role of ERF-VII family in O2 sensing and adaptation to hypoxia in M. truncatula, model plant for legumes, and to understand how NO interacts with O2 in hypoxic signalization in the microoxic environment that characterizes the nodule. We identified four genes belonging to the ERF-VII TF family in the M. truncatula genome, which present a strong similarity with ERF-VII of Arabidopsis. The characterization of this family at the transcriptional level revealed that only MtERF-B2.2 is up-regulated by hypoxia stress and during nodule development. The three others, MtERF-B1.1, MtERF-B1.11 and MtERF-B2.3 are found constitutively expressed in leaves, roots and nodules. To investigated the protein stability of MtERF-B2.1, the closest orthologous to AtRAP2.12 described as O2-sensors in Arabidopsis, in function of O2/NO availability, we realized a fusion protein with the luciferase reporter protein. Our results on Arabidopsis protoplasts indicated that the N-terminal part of MtERF-B2.1 drives its O2-dependent degradation by the N-end rule pathway. The function of MtERF-B2.1 and MtERF-B2.11 was also investigated both in response to hypoxia stress and during the nodulation process using an RNA interference strategy. Silencing of MtERFB2.1 and MtERF-2.11 showed a significant lower activation of several core hypoxia-responsive genes such as ADH1, PDC1, nsHb1 and AlaAT. These double knock-down transgenic roots were also affected in symbiotic interaction with a significant reduction of the nodulation capacity and nitrogen fixation activity in mature nodules. Overall, the results reveal that O2 sensing mechanism is mediated by ERF-VIIs in M. truncatula roots and nodules and that this mechanism, together with downstream targets, is involved in the organ development and ability to efficiently fix nitrogen. Furthermore, results indicated that MtERF-B2.1/B2.11 are positive regulator of the anaerobic metabolism and the Hb-NO cycle– related genes likely in order to activate alternative ATP generation pathways.