In this study, the contributions of learning motivation, reasoning ability, learning orientation and gender to International Baccalaureate and National Program students&rsquo / mitosis and meiosis achievement was investigated. Participants of the study were 472 ninth grade students from a private high school in Ankara. Two hundred nineteen students (46%) were in International Baccalaureate Program and two hundred fifty three (54%) were in National Program. The study was conducted during the 2006-2007 Spring semester. Prior to the introduction of mitosis and meiosis topics, students&rsquo / motivations toward biology learning (self efficacy, active learning strategies, science learning value, performance goals, achievement goals, learning environment stimulation), formal reasoning abilities and learning approaches were measured by Students&rsquo / Motivation Towards Biology Learning Questionnaire, Test of Logical Thinking Ability scale and Learning Approach Questionnaire respectively. After the topics have been covered, a 20 item Mitosis and Meiosis Achievement Test was used to measure achievement in mitosis and meiosis topics. Multiple regression analysis revealed that achievement was explained in positive direction by formal reasoning ability and in negative direction by active learning strategies and rote learning in National Program classes. Self-efficacy and formal reasoning ability had significant contributions to achievement for International Baccalaureate students. The main predictor of achievement was formal reasoning ability for both International Baccalaureate and National Program students, explaining 4.7% and 10.9% variance respectively. Moreover, while 2.9% of the variance in achievement was explained by self efficacy in International Baccalaureate classes, rote learning explained 2.2% of the variance in achievement in negative direction in National Program classes.

Thesis (Ph. D.)--University of Oklahoma. / Bibliography: leaves 139-152.

Made available in DSpace on 2014-06-11T19:26:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-02-21Bitstream added on 2014-06-13T20:33:40Z : No. of bitstreams: 1 pires_wl_me_sjrp.pdf: 611018 bytes, checksum: 961d88c40b2d3d5b170049ad3384f050 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Os triatomíneos são vetores do protozoário Typanosoma cruzi, agente etiológico da moléstia de Chagas. Esses insetos são hematófagos e pertencem à ordem Heteroptera e à família Reduviidae. Disseminada por grandes extensões do Brasil e de outros países latinoamericanos, a doença de Chagas representa um grave e importante problema de saúde pública, caracterizando limitações e dificuldades aos tratamentos. Isso ocorre devido à precariedade apresentada pela vida dos contingentes humanos mais expostos à infecção. Atualmente, a parasitose tem grande participação entre as doenças cardíacas na América do Sul. Segundo a Organização Mundial de Saúde, estima-se que, até a década de 90, por volta de 20 milhões de indivíduos estavam infectados pelo Trypanosoma cruzi nas áreas endêmicas. Dados atuais revelam que o número de pessoas infectadas foi reduzido para 9,8 milhões graças à intensa erradicação desses insetos. No entanto, a vigilância deve continuar, pois é fundamental para se evitar novos casos. Citogeneticamente, o interesse sobre os triatomíneos está em seus cromossomos holocêntricos e no processo incomum da meiose, cuja segregação dos sexuais é pós-reducional. O número básico de cromossomos nos triatomíneos é de 2n=22. No presente trabalho foi analisado a espermatogênese de duas espécies do gênero Triatoma (Triatoma maculata e Triatoma pseudomaculata), com ênfase aos seguintes aspectos: fases da espermatogênese; estrutura cromatínica e dos cromossomos meióticos e acompanhamento do ciclo nucleolar. Essas espécies estão distribuídas principalmente nos estados do Nordeste brasileiro e são consideradas potencialmente vetores do T. cruzi. As espécies analisadas foram cedidas pelo insetário do Serviço Especial de Saúde de Araraquara (SESA), pertencente ao Departamento de Epidemiologia da Faculdade de Saúde Pública da USP. Os... / The triatomines are vectors of the protozoan Typanosoma cruzi, etiological agent of Chagas' disease. These insects are hematophages that belong to the order Heteroptera and to the family Reduviidae. Disseminated through large portions of Brazil and of other Latin American countries, Chagas' disease represents a grave and important public health problem, characterizing limitations and difficulties in treatments. This occurs due to the precariousness presented by life contingent to humans most exposed to the infection. Currently, parasitosis presents high participation among cardiac diseases in South America. According to the World Health Organization, it is estimated that, until the 1990s, approximately 20 million individuals were infected by Trypanosoma cruzi in endemic areas. Current data reveal that the number of persons infected was reduced to 9.8 million by virtue of intense eradiaction of these insects. Nevertheless, vigilance must continue, since it is fundamental to avoiding new cases. Cytogenetically, the interest in triatomines is in its holocentric chromosomes and in its uncommon meiosis process, whose sexual segregation is post-reductional. The basic number of chromosomes in triatomines is 2n=22. The present work analyzed the spermatogenesis of two species of the genus Triatoma (Triatoma maculata and Triatoma pseudomaculata), with emphasis on the following aspects: spermatogenesis phases; structure of chromatin and of meiotic chromosomes and accompaniment of the nucleolar cycle. These species are distributed principally in the states of northeastern Brazil and are considered potential vectors for T. cruzi. The species analyzed were supplied by the insectary of the Special Health Service of Araraquara (SESA), belonging to the Department of Epidemiology in the School of Public Health at USP. The organs studied were...(Complete abstract click electronic access below)

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The objectives of this study were: to determine the presence of prorenin and the receptor of (pro)renin [(P)RR] in cumulus cells (CC) and oocytes; evaluate the role of prorenin in the resumption of oocyte meiosis, ovulation and on levels of plasma progesterone (P4). The mRNA expression of prorenin and (P) RR was evaluated in oocytes and cumulus cells of the bovine species. The mRNA of prorenin and (P)RR was detected in CC, in oocytes only mRNA expression of (P)RR was found. The role of prorenin in the resumption of meiosis was determined from 3 experiments using a co-culture of cumulus-oocyte complex (COC) and follicular halves. In the first experiment, three different concentrations of prorenin (10-10, 10-9, and 10-8M) were tested, which stimulated the resumption of meiosis similar to the positive control and angiotensin II (Ang II). In experiment 2, the co-culture was supplemented with prorenin (10-10M) and aliskiren (direct inhibitor of renin, 10-3M, 10-5M and 10-7M). The aliskiren blocked the resumption of meiosis-induced by prorenin in all concentrations tested. The aliskiren (10-5M and 10-7M) was also evaluated in isolation in a culture system of COCs without follicular halves and the rate of oocytes that resumed meiosis was not different of the positive control. The third experiment was conducted to evaluate the stimulation of meiosis resumption by prorenin independent of Ang II using the combination of prorenin (10-10M) and saralasin [nonspecific Ang II receptor antagonist - Sar (10-5M)], which obtained a rate of oocytes at metaphase I (MI) similar to the positive control and treatments of AngII and prorenin. The prorenin also resumed the oocyte meiosis in a culture system of COCs suplemmented with forskolin, wicth blocks the meiosis by intracellular cAMP accumulation. To evaluate the regulation of (P)RR mRNA in the theca and granulosa cells by LH, cows who achieved follicular diameter ≥12mm after synchronization were submitted to the ovariectomy 0, 3, 6, 12 and 24 hours after GnRH analogue treatment. There was a higher mRNA expression of (P)RR in the theca cells at hour 6; and at hour 3 in the granulosa cells. The effect of (P)RR in ovulation and plasma P4 during luteinization was observed cows that were synchronized and induced by GnRH analogue (IM) associated for intrafollicular aliskiren (10-5M) or PBS (0hour/0day) and the ovulation was evaluated at 24, 48 and 72 hours by ultrasound, wicth was not different of the control (PBS). The leves of plasma P4 was analysed at day 6 and 8 after GnRH and intrafollicular treatment only in the cows that ovulated. The intrafollicular (P)RR blocks decreased plasma P4 at day 6. It was concluded that the prorenin / (P)RR participates in the peri-ovulatory period: in the resumption of oocyte meiosis independently of AngII, in the ovulation by LH stimulation to (P)RR mRNA and in the P4 synthesis during luteinization. / Os objetivos deste estudo foram: determinar a presença de prorenina e receptor de (pro)renina [(P)RR] nas células do cumulus (CC) e em oócitos; avaliar o papel da prorenina na retomada da meiose oocitária; na ovulação e sobre os níveis de progesterona plasmática (P4). A expressão do RNAm de prorenina e (P)RR foi avaliada em oócitos e CC da espécie bovina. O RNAm de prorenina e (P)RR foi detectado nas células do cumulus; nos oócitos ocorreu apenas expressão de RNAm de (P)RR. O papel da prorenina na retomada da meiose foi determinado a partir de 3 experimentos utilizando um sistema de co-cultivo de complexo-cumulus oócito (COC) e metades foliculares. No primeiro experimento, foram testadas três concentrações de prorenina (10-10; 10-9; e 10-8M), as quais estimularam a retomada da meiose semelhante ao controle positivo e angiotensina II (Ang II). No experimento 2, o co-cultivo foi suplementado com prorenina (10-10M) e alisquireno (inibidor direto de renina; 10-3M, 10-5M e 10-7M). O alisquireno bloqueou a retomada da meiose induzida pela prorenina em todas concentrações testadas. O alisquireno (10-5M e 10-7M) também foi avaliado isoladamente em sistema de cultivo de COC sem metades foliculares e a taxa de oócitos que retomaram a meiose não diferiu do controle positivo. O experimento 3 foi realizado para avaliar o estímulo da retomada da meiose pela prorenina independente da Ang II utilizando a associação de prorenina (10-10M) e saralasina [antagonista do receptor da Ang II - Sar (10-5M)], a qual obteve taxa de oócitos em metáfase I (MI) semelhante ao controle positivo e aos tratamentos AngII e prorenina. A prorenina também retomou a meiose oocitária em cultivo de COCs suplementado com forskolin, que bloqueia a meiose pelo acumulo de AMPc intracelular.Para avaliar a possível influência do pico de LH na expressão do RNAm de (P)RR nas células da teca e granulosa, vacas que apresentaram folículo ≥12mm de diâmetro após a sincronização farmacológica do ciclo estral foram ovariectomizadas 0, 3, 6, 12 e 24 horas após aplicação do análogo do GnRH. Houve maior expressão de RNAm de (P)RR nas células da teca na hora 6; e na hora 3 nas células da granulosa. O papel do (P)RR na ovulação e sobre a P4 plasmática durante a luteinização foi verificado em vacas sincronizadas farmacológicamente, induzidas pelo análogo de GnRH (IM) associado ao alisquireno (10-5M) ou PBS intrafolicular (hora 0/ dia 0) e foram avaliadas por ultrason 24, 48 e 72 horas quanto a ovulação, a qual não diferiu do controle (PBS). Os níveis de P4 plasmática foram analisados nos dias 6 e 8 após GnRH e tratamento intrafolicular apenas nas vacas que ovularam, nas quais o bloqueio de (P)RR reduziu P4 no dia 6. Concluiu-se que a prorenina/(P)RR participa do periodo peri-ovulatório: na retomada da meiose oocitária de forma independente da AngII, na ovulação pelo estímulo de LH sobre RNAm do (P)RR e na síntese de P4 durante a luteinização.

Orientador: Maria Tercília Vilela de Azeredo Oliveira / Banca: Alba Regina de Abreu Lima Catelani / Banca: Lilian Castiglioni / Resumo: Os triatomíneos são vetores do protozoário Typanosoma cruzi, agente etiológico da moléstia de Chagas. Esses insetos são hematófagos e pertencem à ordem Heteroptera e à família Reduviidae. Disseminada por grandes extensões do Brasil e de outros países latinoamericanos, a doença de Chagas representa um grave e importante problema de saúde pública, caracterizando limitações e dificuldades aos tratamentos. Isso ocorre devido à precariedade apresentada pela vida dos contingentes humanos mais expostos à infecção. Atualmente, a parasitose tem grande participação entre as doenças cardíacas na América do Sul. Segundo a Organização Mundial de Saúde, estima-se que, até a década de 90, por volta de 20 milhões de indivíduos estavam infectados pelo Trypanosoma cruzi nas áreas endêmicas. Dados atuais revelam que o número de pessoas infectadas foi reduzido para 9,8 milhões graças à intensa erradicação desses insetos. No entanto, a vigilância deve continuar, pois é fundamental para se evitar novos casos. Citogeneticamente, o interesse sobre os triatomíneos está em seus cromossomos holocêntricos e no processo incomum da meiose, cuja segregação dos sexuais é pós-reducional. O número básico de cromossomos nos triatomíneos é de 2n=22. No presente trabalho foi analisado a espermatogênese de duas espécies do gênero Triatoma (Triatoma maculata e Triatoma pseudomaculata), com ênfase aos seguintes aspectos: fases da espermatogênese; estrutura cromatínica e dos cromossomos meióticos e acompanhamento do ciclo nucleolar. Essas espécies estão distribuídas principalmente nos estados do Nordeste brasileiro e são consideradas potencialmente vetores do T. cruzi. As espécies analisadas foram cedidas pelo insetário do Serviço Especial de Saúde de Araraquara (SESA), pertencente ao Departamento de Epidemiologia da Faculdade de Saúde Pública da USP. Os...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The triatomines are vectors of the protozoan Typanosoma cruzi, etiological agent of Chagas' disease. These insects are hematophages that belong to the order Heteroptera and to the family Reduviidae. Disseminated through large portions of Brazil and of other Latin American countries, Chagas' disease represents a grave and important public health problem, characterizing limitations and difficulties in treatments. This occurs due to the precariousness presented by life contingent to humans most exposed to the infection. Currently, parasitosis presents high participation among cardiac diseases in South America. According to the World Health Organization, it is estimated that, until the 1990s, approximately 20 million individuals were infected by Trypanosoma cruzi in endemic areas. Current data reveal that the number of persons infected was reduced to 9.8 million by virtue of intense eradiaction of these insects. Nevertheless, vigilance must continue, since it is fundamental to avoiding new cases. Cytogenetically, the interest in triatomines is in its holocentric chromosomes and in its uncommon meiosis process, whose sexual segregation is post-reductional. The basic number of chromosomes in triatomines is 2n=22. The present work analyzed the spermatogenesis of two species of the genus Triatoma (Triatoma maculata and Triatoma pseudomaculata), with emphasis on the following aspects: spermatogenesis phases; structure of chromatin and of meiotic chromosomes and accompaniment of the nucleolar cycle. These species are distributed principally in the states of northeastern Brazil and are considered potential vectors for T. cruzi. The species analyzed were supplied by the insectary of the Special Health Service of Araraquara (SESA), belonging to the Department of Epidemiology in the School of Public Health at USP. The organs studied were...(Complete abstract click electronic access below) / Mestre

Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2016-08-15T17:53:44Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) A_Marques_PhD_thesis_2016_FINAL.pdf: 9324057 bytes, checksum: 92c1de27f6fa947d7e6b3e74ae09a849 (MD5) / Made available in DSpace on 2016-08-15T17:53:46Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) A_Marques_PhD_thesis_2016_FINAL.pdf: 9324057 bytes, checksum: 92c1de27f6fa947d7e6b3e74ae09a849 (MD5) Previous issue date: 2015-02-15 / capes / Cromossomos holocêntricos são caracterizados pela ausência de constrição primária e apresentam normalmente a proteína centromérica CENH3 distribuída ao longo de um eixo em cada cromátide. Embora muitos organismos com cromossomos monocêntricos apresentem sequências de DNA centroméricas específicas e associadas com a CENH3, nenhuma sequência centromérica havia sido identificada em organismos com cromossomos holocêntricos até o momento. Além disso, vários estudos reportam adaptações meióticas em espécies com cromossomos holocêntricos. Sendo observada em alguns casos uma inversão da ordem dos eventos meióticos (meiose invertida ou pós-reducional). Assim, o presente trabalho objetivou estudar a organização centromérica e a meiose de espécies com cromossomos holocêntricos do gênero Rhynchospora (Cyperaceae). Foi realizada uma análise citogenômica da organização e composição dos holocentrômeros de Rhynchospora pubera (2n = 10), sendo reportada a primeira descoberta de sequências centroméricas em espécies com cromossomos holocêntricos. Foi observado que os holocentrômeros de R. pubera são compostos principalmente por arranjos de DNA satélite (Tyba) e retroelementos centroméricos (CRRh) distribuídos pelo genoma. A análise detalhada da sucessão dos eventos meióticos de R. pubera e R. tenuis (2n = 4) reportou uma prófase inicial semelhante a de monocêntricos. No entanto, foi verificado que as cromátides-irmãs separam para polos opostos durante a anáfase I e os homólogos segregam somente durante a meiose II, comprovando uma meiose invertida para ambas as espécies. Curiosamente, durante a meiose de R. pubera foi observado uma organização diferencial dos centrômeros. Ao contrário do observado em mitose, durante meiose não foi observado a formação de holocentrômeros em forma de linha, sendo, na verdade, observado estruturas centroméricas aglomeradas. O restabelecimento de holocentrômeros em forma de linha se deu durante a primeira mitose do pólen. / Holocentric chromosomes are characterized by the absence primary constriction and normally show the centromeric protein CENH3 distributed along the axis of each chromatid. Although many monocentric organisms show centromere-specific DNA sequences associated to CENH3, no centromeric sequences had been identified in any holocentric organism so far. Furthermore, many studies report meiotic adaptations in holocentric species. In some cases is observed an inversion of the order of meiotic events. This type of meiosis has been named of inverted or post-reductional meiosis and would be exclusive of holocentric organisms. Thus, the present work aimed to study the centromere organization and meiosis of holocentric species of the genus Rhynchospora (Cyperaceae). A cytogenomic analysis of the composition and organization of the holocentromeres of Rhynchospora pubera (2n = 10) has been performed, being reported the first centromeric sequences from a holocentric species. It was observed that the holocentromeres of R. pubera are composed mainly by arrays of satellite DNA (Tyba) and centromeric retrotransposons (CRRh) distributed genomewide. The detailed analysis of the succession of meiotic events of R. pubera and R. tenuis (2n = 4) demonstrated an early meiotic prophase similar to that of monocentric. However, it was verified that sister chromatids separate to opposite poles during anaphase I, while homologs only segregate at meiosis II. These results prove the inverted meiosis for both species. Curiously, it was observed during meiosis of R. pubera a differential organization of centromere units. In contrast to the observed in mitosis, during meiosis we did not observed the formation of line-like holocentromeres, being in fact observed the formation of cluster-like holocentromeres. The reestablishment of a line-like holocentromere occurred during the first pollen mitosis.

O óxido nítrico (NO) é um mensageiro químico detectado em vários tipos celulares como células endoteliais, neurônios e macrófagos, desempenhando também funções variadas como vasodilatação, neurotransmissão e indução de morte celular. O NO é gerado pela atividade da enzima óxido nítrico sintase (NOS), a qual foi detectada em vários órgãos incluindo o sistema reprodutor. O sistema NOS/NO parece desempenhar papel importante na maturação oocitária entre outras funções. No entanto, apesar das evidências, há poucos estudos sobre o possível papel desse sistema em oócitos da espécie bovina. O presente estudo teve por objetivo investigar a importância do sistema NOS/NO na maturação in vitro (MIV) de oócitos bovinos. Para isso, foram avaliados os efeitos da inibição da NOS durante a MIV na presença de concentrações crescentes do inibidor de NOS (L-NAME, 0-1mM) e do aumento do NO durante a MIV na presença de concentrações crescentes do doador de NO (SNAP, 0-1mM) sobre a taxa de maturação (metáfase II) e formação de blastocistos após a fecundação in vitro. Também foi avaliado o efeito da pré-maturação com butirolactona (10µM BLI), seguida de MIV, na presença ou não de doador ou inibidor de NO em cada fase de cultivo, sobre o desenvolvimento de blastocistos. Após 22h de MIV os grupos tratados com L-NAME apresentaram uma taxa de metáfase II (MII) inferior (~80%, P<0,05) ao controle (95,5%). A taxa de blastocisto foi similar entre os grupos (34 a 41,5%, P>0,05). Apenas 7,2% (P<0,05) dos oócitos maturados com a maior concentração de SNAP (10-3M), atingiram o estádio de MII. Os demais tratamentos (71,6; 72,4 e 54,8% para controle, 10-7 e 10-5M, respectivamente) não diferiram entre si (P>0,05). Altos níveis de SNAP (10-3M) bloquearam o desenvolvimento embrionário, enquanto os demais tratamentos apresentaram cerca de 38% de blastocistos (P>0,05). As taxas de blastocistos (26,3 a 34,1%) e de eclosão (14,8 a 22,0%) adicionando ou não L-NAME em baixa concentração (10-7M) durante a pré-maturação, a maturação ou ambas as fases foram similares (P>0,05). Também não houve diferença (P>0,05) na taxa de blastocistos (25,5 a 39,7%) com a adição ou não de baixa concentração de SNAP (10-7M) durante a pré-maturação, a maturação ou ambas as fases. O grupo com SNAP (10-7M) na pré-maturação e MIV superou a taxa de eclosão (27,5%, P<0,05) dos demais grupos que tiveram SNAP adicionado somente no bloqueio, na MIV ou sem adição de SNAP (14,2 a 18,6 %, P>0,05). Esses resultados exibiram o duplo efeito do NO sobre oócitos bovinos, que tiveram a maturação reduzida com a inibição da síntese de NO e a maturação nuclear e citoplasmática bloqueadas pelo excesso de NO. / Nitric oxide (NO) is a chemical messenger detected in several cell types such as endothelial cells, neurons and macrophages, performing also varied functions as vasodilatation, neurotransmission and induction of cell death. NO is generated by the activity of the enzyme nitric oxide synthase (NOS), which has been detected in several organs including the reproductive system. The NOS/NO system seems to play an important role in oocyte maturation besides other functions. However, despite the evidence, there are few studies on the possible role of this system in bovine oocytes. The present study aimed to investigate the importance of the NOS/NO system on in vitro maturation (IVM) of bovine oocytes. The effects of NOS inhibition during IVM in the presence of increasing concentrations of NOS inhibitor (L-NAME, 0-1mM) and of the increase in NO during IVM with the NO donor SNAP (0-1mM) on maturation rates (metaphase II) and on blastocyst development after in vitro fertilization were assessed. The effect of prematuration with butyrolactone I (10µM BLI) followed by IVM, in the presence or not of NO inhibitor or donor in each culture period on blastocyst development was also investigated. After 22h IVM, L-NAME treated groups showed a lower (~80%, P<0.05) metaphase II (MII) rate when compared with controls (95.5%). Blastocyst rates were similar among all groups (34 to 41.5%, P>0.05). Only 7.2% (P<0.05) of oocytes matured with the highest SNAP concentration (10-3M) reached MII. The other treatments (71.6; 72.4 and 54.8% for control, 10-7 and 10-5M, respectively) were similar among them (P>0.05). High SNAP concentration (10-3M) blocked blastocyst development, while the other treatments presented about 38% blastocyst rates (P<0.05). Blastocyst (26.3 to 34.1%) and hatching rates (14.8 and 22.0%) were similar (P>0.05) when low L-NAME concentration (10-7M) was added or not during prematuration, maturation or both. Blastocyst rates (25.5 to 39.7%) were also similar (P>0.05) whether SNAP (10-7M) was added or not during prematuration, IVM or both. When low concentration of SNAP (10-7M) was added during both prematuration and IVM, hatching rates were increased (27.5%, P<0.05) when compared with oocytes cultured in the presence of SNAP only during prematuration or IVM or without it (14.2 to 18.6 %, P>0.05). These results shoe the dual effect of NO on bovine oocytes, which had maturation rates decreased when NO synthesis was inhibited and nuclear maturation and blastocyst development were blocked by excess NO.

La recombinaison méiotique via les Crossing-Overs (COs) est le principal mécanisme permettant le brassage de la diversité génétique. Cependant, le nombre et la position des COs entre paires de chromosomes homologues sont strictement régulés, limitant la séparation des loci en sélection variétale. Dans le cas du colza B. napus, l’utilisation d’allotriploïdes (AAC, 2n=3x=29), issus du croisement entre le colza (AACC, 2n=4x=38) et l’un de ses progéniteurs B. rapa (AA, 2n=2x=20), permet d’augmenter considérablement le nombre de COs entre chromosomes homologues A. L’objectif de cette étude était de déterminer les conséquences d’une telle variation sur la distribution des COs le long des chromosomes ainsi que d’identifier des facteurs régulant ce phénomène. Suite à la production et à la caractérisation cytogénétiques d’hybrides F1 présentant différents caryotypes, la recombinaison homologue a été évaluée par des analyses génétiques via des marqueurs SNPs physiquement ancrés sur l’ensemble duNous avons montré que l’addition du génome C chez les allotriploïdes conduit toujours à (1) la formation de COs surnuméraires, dont le nombre varie fonction des méioses mâle/femelle et du fond génétique, (2) une modification des profils de recombinaison, notamment au voisinage des centromères, et (3) une réduction de l’intensité d’interférence. De plus, nous avons révélé que le contrôle génétique de ces variations est imputé à des chromosomes C spécifiques et aurait divergé dans un contexte polyploïde. Nous avons donc identifié un levier permettant d’optimiser le brassage de la diversité gén / Meiotic recombination via crossovers (COs) is the main mechanism responsible for mixing genetic diversity. However, the number and position of COs between the pairs of homologous chromosomes are strictly regulated, limiting the loci separation in plant breeding. In the case of the rapeseed B. napus, the use of allotriploids (AAC, 2n=3x=29), resulting from the cross between rapeseed (AACC, 2n=4x=38) and one of its progenitors B. rapa (AA, 2n=2x=20), allows a substantial increase of the number of COs between homologous A chromosomes. The objective of this study was to determine the consequences of such a variation on the distribution of COs along the chromosomes and to identify factors regulating this phenomenon. Following the production and cytogenetic characterization of F1 hybrids with different karyotypes, homologous recombination was assessed by genetic analyzes via SNPs markers physically anchored on the whole A genome.We showed that the additional C genome in allotriploids always leads to (1) the formation of extra COs, for which the number depends on the male/female meiosis and the genetic background, (2) the modification of the recombination landscapes, especially in the vicinity of centromeres, and (3) the decrease of CO interference. In addition, we revealed that the genetic control of these variations is assigned to specific C chromosomes and could have evolved in a polyploid context. We have therefore identified a way to optimize the shuffling of genetic diversity in rapeseed breeding.

Au vignoble, des nuits froides peuvent se produire pendant la floraison et en particulier au moment de la méiose ovulaire dans les fleurs. La vigne est particulièrement vulnérable puisque la méiose ovulaire se produit lors de la transition du métabolisme de la plante d'un état hétérotrophe à un état autotrophe. Bien que la feuille soit l'organe photosynthétique principal, la jeune inflorescence de vigne possède un statut particulier et participe activement à l'effort reproducteur en exportant la majorité du carbone qu'elle assimile, permettant ainsi le développement des feuilles. Par conséquent, le métabolisme carboné de l'inflorescence lors du développement reproducteur peut être impliqué dans le futur rendement. Chez la vigne, le phénomène de coulure, propre à chaque cépage, peut engendrer des pertes de rendement importantes lorsque la plante est exposée à un stress. Le Pinot noir (PN) est considéré comme un cépage relativement « résistant » à la coulure alors que le taux d'abscission chez le Gewurztraminer (GW) augmente considérablement lors de conditions climatiques défavorables. Chez le PN, l'inflorescence effectue une photosynthèse inférieure et une respiration de nuit supérieure à celle de la feuille. L'activité et la régulation des deux photosystèmes sont très différentes entre ces deux organes lors des premiers stades de développement et les activités des deux photosystèmes sont supérieures au niveau de l'inflorescence. Néanmoins, la protection de la chaîne photosynthétique contre l'excès d'énergie est plus efficace dans la feuille. Contrairement à la feuille, l'activité photosynthétique de l'inflorescence évolue au cours de son développement. En effet, l'activité de la chaîne photosynthétique ainsi que la photosynthèse nette diminuent progressivement au cours de la floraison et le flux cyclique des électrons se met en place pour être finalement supérieur à celui de la feuille. L'activation de ce flux peut alors permettre une synthèse accrue d'ATP, une protection de la chaîne photosynthétique contre les dommages provoqués par un excès d'énergie ou encore la réparation des photosystèmes. Lorsque la nuit froide survient lors de la méiose ovulaire, le métabolisme carboné de l'inflorescence de PN est différemment modifié selon l'intensité du stress. Ainsi, après une nuit à 4°C, la modification de l'activité photosynthétique de l'inflorescence est due à des limitations de nature non-stomatique alors qu'après une nuit à 0°C, cette modification est due à des limitations de nature stomatique. Une nuit à -3°C altère profondément l'activité photosynthétique de l'inflorescence. Ces nuits froides induisent également une accumulation de glucides. Lors du développement floral en conditions optimales, le PN et le GW présentent une activité photosynthétique et un métabolisme carboné différents. La régulation des flux linéaire et cyclique des électrons est également différente. Ce dernier semble avoir une fonction différente chez ces deux cépages avec notamment une possible implication dans la réparation du PSII et/ou dans une synthèse d'ATP accrue à la fin du processus de floraison chez le PN. La chaîne photosynthétique du GW semble mieux protégée ce qui peut expliquer le rendement supérieur de ce cépage en conditions optimales. Néanmoins, l'exposition à une nuit froide entraine des modifications différentes de l'activité de l'inflorescence chez ces cépages avec une perturbation plus importante chez le GW. En effet, chez ce cépage, seule la photosynthèse nette est perturbée suite à la nuit froide alors que chez le PN, les processus de photosynthèse et de respiration sont modifiés. L'activité de la chaîne photosynthétique ainsi que l'activité métabolique de l'inflorescence de GW est également davantage affectée. De manière intéressante, nos résultats suggèrent que ces différentes perturbations de l'activité de l'inflorescence sont dues à des régulations différentes. / In the vineyard, cold night can occur during flowering and particularly at time of female meiosis in flowers. In grapevine, stress vulnerability is enhanced because female meiosis occurs when the whole plant physiology is switching its carbon nutrition from mobilization of wood reserves to photosynthesis in the leaves. Nevertheless, although leaf is the major photosynthetic organ, in grapevine, the young inflorescence has a particular status and takes part in the reproductive effort by exporting the majority of assimilated carbon, allowing in particular the leaves development. Consequently, the inflorescence metabolism during this phase can ultimately determines yield. In grapevine, coulure phenomenon, differing according to the cultivar, can generate important yield losses when a stress occurs. Pinot noir (PN) is considered as a cultivar relatively “resistant” to coulure phenomenon whereas Gewurztraminer (GW) abscission rate considerably increases under environmental stress.In PN, inflorescence performs a lower photosynthesis and a higher dark respiration than leaves. Functioning and regulation of PSI and PSII are very different between inflorescence and leaf during the first developmental stages and activities of these photosystems are higher in the inflorescence. Nevertheless, the photosynthetic chain against excess energy is more efficient in the leaf. Contrary to the leaf, the inflorescence photosynthetic activity evolves during the floral development. Indeed, photosynthetic chain activity and net photosynthesis progressively decrease and the cyclic electron flow appears and is higher than in leaf. This activation could provide ATP, protection against photodamage or repair of the photosystems.When cold night occurs at the female meiosis stage, carbohydrate metabolism of the PN inflorescence is differently modified according to the intensity of the cold stress. At 4°C, photosynthesis in the inflorescence is impaired through non-stomatal limitations, whereas at 0°C it is affected through stomatal limitations. A freezing night (-3°C) severely deregulates photosynthesis in the inflorescence. Cold nights also induce accumulation of sugars.Comparing PN and GW, different photosynthetic activity and carbohydrate metabolism have been showed during the floral development under optimal conditions. Regulations of the linear and cyclic electron flow are also different and the cyclic electron flow seems to have a different aim with particularly an implication in the recovery of PSII and ATP synthesis at the end of the flowering process in PN. GW could have higher protection of the photosynthetic chain and consequently gets a higher yield under optimal conditions. Nevertheless, chilling night impacts differently the activity of the inflorescences of both cultivars with higher modification in GW inflorescence. Indeed, in this cultivar, only the net photosynthesis is altered whereas in PN, both net photosynthesis and respiration processes are modified. The photosynthetic chain activity and metabolical activity of the inflorescence are also more affected by the cold night in GW. Interestingly, our results suggest that the different fluctuation of the inflorescence activities as response to the chilled night is due to different regulations.

Oxymonads are a group of poorly studied protists living as intestinal endosymbionts in the gut of insects and vertebrates. In this thesis I focused on the study of phylogeny, genomics and cell biology of oxymonads. Using culture-based approaches, we uncovered the hidden diversity of small oxymonads and described one new genus and six new species. In Monocercomonoides exilis, the only oxymonad with a published genome, we investigated the genome organization using fluorescence in situ hybdridization (FISH) against the telomeric regions and single-copy genes. Our results show that the genome is most probably haploid being organized in 6-7 chromosomes. Annotation of the genome revealed that the DNA replication and repair mechanisms in M. exilis are canonical and they seem more complete than those of other metamonads whose genomes are available. Although M. exilis lacks in any traces of mitochondria, its genome annotation revealed that other cellular systems do not markedly differ from other eukaryotes. Our taxon-rich phylogenetic analyses suggested that the genus Monocercomonoides is closely related to the oxymonad Streblomastix strix, which is found exclusively in the gut of the termites. Streblomastix strix, as opposed to M. exilis, is highly adapted to harbour bacterial ectosymbionts. Since S. strix...