Developmental exposure to aryl hydrocarbon receptor (AhR) agonists in fish causes severe defects in the cardiovascular system. However, the effects of acute AhR agonist exposure on the adult fish cardiovascular system as well as the genes mediating developmental AhR-induced deformities remain unclear. In this thesis, two studies were carried out to address these issues. Before experiments could begin, methods for quantitative real-time reverse transcriptase polymerase chain reaction (rtrt-PCR) as well as larval exposure and rearing were developed, validated, and optimized.<p> Following method development, a series of experiments was performed on adult zebrafish (<i>Danio rerio</i>) to assess how expression of cytochrome P450 (CYP) and cyclooxygenase (COX) enzyme mRNA in hepatic and vascular tissues is altered after intraperitoneal injection of AhR agonists benzo(a)pyrene (BaP) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) alone and in combination with the purported AhR antagonists resveratrol (Res) or alpha-naphthoflavone (ANF). Both TCDD and BaP induced similar patterns of gene expression in arteries, although with different efficacies, and had slightly different effects in hepatic tissues. Resveratrol was generally without effect in all treatment groups and tissues with the exception of reducing TCDD-induced CYP1C2 in vascular tissues. In contrast, ANF antagonized TCDD- and BaP-induced changes, as well as reduced baseline gene expression in liver. However, in arteries, ANF alone acted as an agonist to increase expression of several of the genes investigated.<p> The second series of experiments involved zebrafish eggs aqueously exposed to BaP or TCDD alone and in combination with Res or ANF. Whole larvae CYP and COX isoform mRNA expression was quantified at 5 and 10 days post-fertilization (dpf), then correlated with developmental phenotype. Both TCDD and BaP caused concentration-dependent AhR-associated deformities with a significant increase in mortalities by 10 dpf and increased CYP1A mRNA expression, while TCDD alone decreased CYP1C2 expression. BaP/ANF co-exposure exhibited the highest rate of deformities and mortalities at both 5 and 10 dpf, caused marked alterations in cardiac and vascular morphology at 10 dpf, and increased CYP1A expression. Furthermore, ANF exhibited additive agonistic effects on gene expression with both BaP and TCDD. Correlation analyses revealed that gene expression at 5 dpf, but not 10 dpf, was strongly linked to abnormal cardiac and vascular phenotypes at 10 dpf with several genes related to cardiac development and one primary gene linked to vascular development.

Le cytochrome b6f est un complexe majeur de la chaîne photosynthétique oxygénique de par son activité quinol:plastocyanine oxydoréductase, qui contribue à la formation d'ATP via un transfert d'électrons couplé à un transfert de protons. La présence d'un hème c particulier lié par une seule liaison covalente, l'hème ci, au sein du site de réduction de quinone Qi du cytochrome b6f constitue une différence notable en comparaison avec son homologue de la chaîne respiratoire, le cytochrome bc1. Un cytochrome b6f dépourvu d'hème ci est dégradé, sa faible accumulation ne permet pas une croissance photosynthétique. Cette observation a donné lieu à une recherche de suppresseurs permettant une plus grande accumulation de cytochrome b6f dont la fonction même altérée, serait suffisante pour assurer une croissance photosynthétique. Cette approche génétique de recherche de suppresseur a été entreprise chez Chlamydomonas reinhardtii. Ce travail de thèse a permis l'isolation et la caractérisation d'un mutant de la protéase FtsH1 (mutation R420C qui affecterait l'activité ATPasique). Le mutant ftsh1-1 s'est révélé être un outil puissant pour l'étude fonctionnelle de complexes mutés autrement dégradés. Une approche multidisciplinaire combinant expériences de génétique, biochimie, physiologie et biophysique a démontré notamment que : (i) le mutant QiKO, dont le complexe b6f est dépourvu des hèmes bh et ci, peut pousser de manière phototrophique malgré un Q-cycle cassé, (ii) l'absence d'hème ci lié covalemment, pour le mutant Rccb2, génère une photosensibilité exacerbée en présence d'oxygène, ce qui sous-tend un rôle pour l'hème ci dans un environnement riche en oxygène, (iii) la protéase FtsH exerce un contrôle qualité global des complexes majeurs photosynthétiques.

L'acclimatation au froid chez les plantes est un processus dynamique qui nécessite un apport énergétique indispensable à l'induction de la tolérance au gel. Cette énergie est fournie par l'augmentation de la capacité photosynthétique durant l'acclimatation au froid à la suite d'une reprogrammation globale des enzymes photosynthétiques et respiratoires. Par ailleurs, des études ont déjà démontré une augmentation de biomasse chez les variétés de blé d'hiver et de printemps, en réponse au froid et à une concentration élevée de CO₂. Afin d'élucider le mécanisme impliqué dans la régulation énergétique durant l'acclimatation au froid et le rôle d'une concentration élevée de CO₂, nous avons entrepris d'étudier l'implication de plusieurs enzymes clés de la photosynthèse et de la respiration, en réponse aux basses températures durant la croissance chez deux variétés de blé : Norstar, une variété d'hiver et Katepwa, une variété de printemps. Parmi les enzymes régulées à la hausse, on a identifié la cytochrome c oxydase (COX II), une enzyme clé impliquée dans la synthèse d'ATP an niveau de la mitochondrie. Nos résultats ont révélé qu'en réponse au froid, la teneur en protéines solubles totales a augmenté de 39% et 83% respectivement chez Katepwa et Norstar après 30 jours. Au cours de l'acclimatation au froid (4°C), on observe une forte accumulation des protéines COX II chez Norstar (très tolérant au gel) et une faible accumulation de ces protéines chez Katepwa (sensible au gel). Nos résultats ont aussi montré une augmentation de l'activité cytochrome c oxydase chez les 2 variétés. En effet, on observe une hausse de 1,5 fois chez les plantes Norstar acclimatées au froid comparativement à leur témoin (20°C), alors que cette hausse est de 40% chez Katepwa. Ces données montrent qu'il existe une corrélation entre la tolérance au froid et l'accumulation des protéines COX II. Par ailleurs, une exposition des plantes de Norstar à une concentration élevée de CO₂ (770 ppm) durant 80 heures entraîne une réduction de l'activité cytochrome c oxydase de 20% chez les plantes non acclimatées et de 50% chez les plantes acclimatées au froid. Cependant, une exposition chronique des plantes de Norstar à une concentration élevée de CO₂ entraîne une hausse de l'activité cytochrome c oxydase de 40% chez les non acclimatées et 50% chez les acclimatées. Chez Katepwa, cette hausse est de 30% aussi bien chez les plantes acclimatées au froid que chez les plantes non acclimatées. En réponse à une concentration élevée de CO₂, la cytochrome c oxydase s'exprime de manière différentielle entre les deux variétés de blés étudiées. En conclusion, la cytochrome c oxydase est régulée par le CO₂ et le froid chez le blé et intervient probablement dans la tolérance au CO₂. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : cytochrome c oxydase, acclimatation, CO₂, froid, Triticum aestivum L.

Developmental exposure to aryl hydrocarbon receptor (AhR) agonists in fish causes severe defects in the cardiovascular system. However, the effects of acute AhR agonist exposure on the adult fish cardiovascular system as well as the genes mediating developmental AhR-induced deformities remain unclear. In this thesis, two studies were carried out to address these issues. Before experiments could begin, methods for quantitative real-time reverse transcriptase polymerase chain reaction (rtrt-PCR) as well as larval exposure and rearing were developed, validated, and optimized.<p> Following method development, a series of experiments was performed on adult zebrafish (<i>Danio rerio</i>) to assess how expression of cytochrome P450 (CYP) and cyclooxygenase (COX) enzyme mRNA in hepatic and vascular tissues is altered after intraperitoneal injection of AhR agonists benzo(a)pyrene (BaP) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) alone and in combination with the purported AhR antagonists resveratrol (Res) or alpha-naphthoflavone (ANF). Both TCDD and BaP induced similar patterns of gene expression in arteries, although with different efficacies, and had slightly different effects in hepatic tissues. Resveratrol was generally without effect in all treatment groups and tissues with the exception of reducing TCDD-induced CYP1C2 in vascular tissues. In contrast, ANF antagonized TCDD- and BaP-induced changes, as well as reduced baseline gene expression in liver. However, in arteries, ANF alone acted as an agonist to increase expression of several of the genes investigated.<p> The second series of experiments involved zebrafish eggs aqueously exposed to BaP or TCDD alone and in combination with Res or ANF. Whole larvae CYP and COX isoform mRNA expression was quantified at 5 and 10 days post-fertilization (dpf), then correlated with developmental phenotype. Both TCDD and BaP caused concentration-dependent AhR-associated deformities with a significant increase in mortalities by 10 dpf and increased CYP1A mRNA expression, while TCDD alone decreased CYP1C2 expression. BaP/ANF co-exposure exhibited the highest rate of deformities and mortalities at both 5 and 10 dpf, caused marked alterations in cardiac and vascular morphology at 10 dpf, and increased CYP1A expression. Furthermore, ANF exhibited additive agonistic effects on gene expression with both BaP and TCDD. Correlation analyses revealed that gene expression at 5 dpf, but not 10 dpf, was strongly linked to abnormal cardiac and vascular phenotypes at 10 dpf with several genes related to cardiac development and one primary gene linked to vascular development.

Potassium cyanide (KCN) is an inhibitor that reduces the activity of terminal oxidases in electron transport system of Klebsiella oxytoca. Previous research verified that K. oxytoca could induce cyanide-resistant respiration pathway when cells were grown in KCN condition. To address the role of cyanide-resistant pathway in regulating the respiration of bacterium in KCN incubation, 8-hydroxyquinoline (8-HQ), an inhibitor of cyanide-resistant pathway, was added to the bacterial suspension pretreated with KCN. This experiment was devised into 4 groups as below: (1). TSB (without KCN or 8-HQ), (2). TSB + 1 mM KCN, (3). TSB + 100 £gM 8-HQ, and (4). TSB + 1 mM KCN+ 100 £gM 8-HQ. Our results show 100 £gM 8-HQ exerted it slight toxicity to bacterial growth. However, the bacterial growth was severely impaired when the cells treated with KCN and 8-HQ concurrently as evidenced by the lower oxygen uptake rate of cells in comparison with the control group (without addition of 8-HQ). Furthermore, K. oxytoca grown in growth medium containing 100 £gM 8-HQ produced more significant H2O2. Thus we suggested that cyanide-resistant respiration of K. oxytoca could protect the cells from H2O2 damage. Since cytochrome d has been implicated in having an important role in KCN degradation in the K. oxytoca, we constructed cyd- mutant to explore the possible role in KCN degradation. In this study the sequence of the genes encoding this terminal oxidase (cydAB) of K. oxytoca mutant were deduced. Results showed that cytochrome d oxidase of K. oxytoca is not a cyanide-insensitive oxidase, but playing an important role in KCN degradation.

Family Pinguipedidae belong to the class Actinopterygii, subclass Neopterygii, order Perciformes, suborder Trachinoidei. Currently the interrelationships of the genera within this family and among the families in the Trachinoidei remain unequivocal. Also, whether the Cheimarrichthys should be included in the family Pinguipedidae has also been a controversial issue. This study aimed to reconstruct phylogenetic hypotheses in order to resolve these questions. Species of the Parapercis and Kochichtys in the family Pinguipedidae occur Taiwan. This study used osteological characters, 16S rRNA and Cyt b sequences to conduct phylogenetic analysis such that hypotheses can be proposed. The results revealed the monophyly of Parapercis, a taxonomic view consistent to the prevailary classification. Summarizing all the results, the 17 Parapercis species analysed can be divided into 4 groups. They are (1) Parapercis aurantiaca¡BP. decemfasciata¡BP. mimaseana¡BP. multifasciata¡BP. muronis¡Btwo morphotypes of P. sexfasciata¡F(2) P. cephalopunctata¡BP. clathrata¡BP. hexophthalma¡BP. kamoharai¡BP. tetracantha¡BP. xanthozona¡F(3) P. cylindrica and P. snyderi¡F(4) P. maculata¡BP. ommatura and P. somaliensis. Two color morphotypes have been shown for Parapercis sexfasciata. Data of the present study revealed that the ¡§ autapomorphic¡¨ osteological character known only in Kochichtys also occurred in three Parapercis species. This result supports a close relationship between these species. However, it also challenges the validity of the generic status of Kochichtys. About the dabate of the phylogenetic position of Cheimarrichthys, it should be put into its own family, Cheimarichthyide, rather than placed in the Pinguipedidae. The hypothesis for the sister group of Pinguipedidae to the Cheimarichthyide is not supported by all the data in this study completely. Morphological and molecular evidences are incongruence for closest phylogenetic relationship. Similar results were also obtained when the molecular sequences were analysed using different methods. More data analyses are needed for complete and reliable results. The present study suggests that the Trachinoidei is not a monophyletic group.

Bats of the genus Scotophilus are distributed throughout sub-Saharan Africa, parts of southern and Southeast Asia, a majority of the Indomalayan Islands, Reunion Island, and Madagascar. The genus is composed of 14 recognized species with seven distributed throughout sub-Saharan Africa including: (S. dinganii (A. Smith, 1833), S. leucogaster (Cretzschmar, 1830), S. nigritellus de Winton, 1899, S. nigrita (Schreber, 1774), S. nucella Robbins, 1983, S. nux Thomas, 1904, and S. viridis (Peters, 1852). The remaining species include four from southern and southeast Asia (S. celebensis Sody, 1928; S. collinus Sody 1936; S. heathi (Horsfield, 1831); S. kuhlii Leach, 1821), two on Madagascar (S. sp. nov. Goodman et al., in press; and S. robustus Milne-Edwards, 1881), and one endemic to Reunion Island (S. borbonicus (E. Geoffroy, 1803). The systematics and taxonomy of this genus have been controversial and continue to be confusing. The genus is plagued with problems in species definition and the systematic relationships among members of the genus are poorly understood. The major goal of this study was to use a molecular phylogenetic approach to clarify some of the controversy and confusion surrounding the members of this genus. Nucleotide differences from mtDNA and the Y chromosome were used to examine phylogenetic patterns within Scotophilus. Based on these data two new species of Scotophilus were identified. Phylogenetically, African Scotophilus were found to comprise a monophyletic group with S. nux as the most basal African taxon. Overall, the Asian S. kuhlii was the most basal taxon. A distant relationship was identified between S. kuhlii and S. heathi, the other Asian species examined. The multiple origins of Malagasy Scotophilus are apparent as the two Malagasy taxa in the study do not share a sister-group relationship. The large bodied S. nigrita is closely related to S. dinganii and the S. dinganii-like species all share a close relationship. S. nigrita has a S. dinganii-like mtDNA haplotype and a very distinct zfy haplotype, suggesting a possible hybridization event with a S. dinganii-like ancestor.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 128-147).

Thèse de doctorat : Sciences Agronomiques : INPL : 2006. / Titre provenant de l'écran-titre. Bibliogr.

Thèse doctorat : Ecotoxicologie : Metz : 2000. / Thèse soutenue sur ensemble de travaux. Bibliogr. Index.