<p> It was known, prior to this study, that there is a factor, or factors, in the centromere-proximal region of Neurospora sitophila which affect recombination near the centromere whether it is in Neurospora sitophila or transferred to Neurospora crassa. A location of this factor, or factors, was performed using tetrad and prototroph analysis. Further mapping of linkage group I of Neurospora crassa was undertaken when the Neurospora sitophila centromere-proximal region was present.</p> / Thesis / Master of Science (MSc)

Les tilapias (espèces Oreochromis) sont le second groupe le plus important de poissons dans l'aquaculture mondiale ainsi qu'une des premières sources de protéines animales pour des millions de personnes dans les pays en cours de développement. En effet, Les tilapias ont la plupart des qualités requises dans le monde aquacole comme un taux de croissance important et une résistance aux maladies. Cependant leurs reproductions précoces et continues provoquent une surpopulation des bassins et un nanisme des individus. Pour surmonter ces difficultés, il s'agit de créer de nouvelles méthodes de contrôle du sexe (génétique et température) pour une meilleure compréhension de la détermination du sexe chez le tilapia. La détermination sexuelle chez les tilapias est complexe. En effet, le sexe est influencé par des facteurs génétiques majeurs (XX/XY), des facteurs génétiques mineur (sur les autosomes : LG3, LG23) et la température. Au cours des dernières années, de nombreuses ressources génomiques ont été progressivement développées (Bac End Sequences, Expressed sequence Tag, physical map, RH map…). Dans ce travail de thèse nous avons cherché à identifier, par des approches in silico, des gènes liés au sexe, en nous intéressant, en particulier, à ceux localisés sur LG3. Nous avons divisé notre travail en deux étapes. La première recouvre des travaux préliminaires de collecte et de comparaison d'informations existantes. Elle s'est concrétisée par la création d'une carte physique comparée entre le génome complet de l'épinoche et des BES du tilapia ainsi que d'une carte RH du tilapia. La deuxième étape porte sur l'analyse du chromosome correspondant au LG3 (Chr3). Nous avons pu grâce aux méthodes, outils et données développés lors de la première étape, reconstituer le Chr3, l'annoter et faire une liste de gènes impliqués dans la cascade du sexe chez le tilapia du Nil. / Tilapias (Oreochromis spp.) are the second most important fish group in aquaculture and a primary source of animal protein for millions of people in developing countries. Indeed, Tilapias have most of the qualities required in aquaculture such as a good growth-rate and resistance to diseases. Nevertheless, their early and constant reproduction leads to tank overpopulation and dwarfism of individuals. To overcome this, new sex controlling methods (genetics and temperature) are being studied to better understand the sex determination in tilapia. Sex determination in tilapia is complex since sex is influenced by major genetic factors (XX/XY), minor genetic factors (on an autosome: LG3, LG23) and temperature factors. Over the past years a great effort has been done to increase the genomic tools in tilapia by obtaining data on Bac End Sequences (BES), Expressed Sequence tags (EST), physical map, RH map.... The objective of our work is to identify, by in silico approaches, genes associated to sex, especially the ones located on the linkage group LG3. We divided our work in two steps. The first work is to collect heterogeneous and available information existing on tilapia using comparative genomic analyses. This step led to the creation of a comparative physical map between the complete genome of stickleback and the BES of tilapia along with a tilapia RH map. The second step is to analyse the chromosome corresponding to the LG3 (Chr3). Using methods, tools and data developed during the first step, we recreated the Chr3, annotated it and listed the genes involved in the sex cascade in Nile tilapia.

The commercialization of proton exchange membrane (PEM) fuel cells depends largely upon the development of PEMs whose properties are enhanced over current perfluorinated sulfonic acid PEMs. Understanding how a PEM's molecular weight and morphology affect its relevant performance properties is essential to this effort. Changes in molecular weight were found to have little effect on the phase separated morphologies, water uptake, and proton conductivities of random copolymers. Changes in block length, however, have a pronounced effect on multiblock copolymers, affecting surface and bulk morphologies, water uptake, proton conductivity, and hydrolytic stability, suggesting that multiblock copolymer PEM properties may be optimized by changes in morphology. A major goal of current proton exchange membrane fuel cell research involves developing high temperature membranes that can operate at ~120 °C and low humidites. Multiblock copolymers synthesized from 100% disulfonated poly(arylene ether sulfone) (BPSH100) and naphthalene polyimide (PI) oligomers may be an alternative. At block lengths of ~15 kg/mol they displayed no morphological changes up to 120 °C or even higher. Water desorption was observed to decrease with increasing block length. The copolymers exhibited little to no water loss during a 200 °C isotherm in contrast to random BPSH copolymers and Nafion. A BPSH100-PI multiblock copolymer with large block length appears to have morphological stability and retain water at temperatures exceeding 120 °C, suggesting its candidacy as a high temperature PEM. A growing number of alternative PEM research efforts involve multiblock copolymer chemistries, but little emphasis is placed on the methods used to couple the oligomers. Fluorinated linkage groups can help increase block efficiency during coupling, but their effect on a PEM is not well-known. The choice of linkage type, hexafluorobenzene (HFB) vs. decafluorobiphenyl (DFBP), appears to have small but observable influences on multiblock copolymers with disulfonated and unsulfonated poly(arylene ether sulfone) oligomers. DFBP linkages promote greater phase separation than HFB linkages, resulting in increased stiffness, decreased ductility, and increased proton conductivity at low humidities. DFBP linkages also promote more surface enrichment of fluorine, causing changes in surface morphology and slightly increased water desorption, but determining the impact on actual fuel cell performance requires further research. / Ph. D.

Chickpea (Cicer arietinum L.) was recently introduced to the Canadian prairies, a region which has a short growing season in which crop maturation often occurs under cool and wet conditions. To improve the yield of chickpea, crop duration must closely match the available growing season. The objectives of this study were to: i) examine the days to flowering of diverse chickpea accessions grown in either long or short-days; ii) examine the days to flowering of selected chickpea accessions grown in a range of thermal regimes combined with either long or short days and to examine the interaction between photoperiod and day and night temperatures on crop duration; iii) determine the timing and duration of the photoperiod-sensitive phase in selected chickpea accessions, and vi) determine the genetic basis of the association between flowering time and reaction to ascochyta blight in chickpea. A wide variation was observed in chickpea accessions for their response to flowering under long (16/8 hours day /night) and short days (10/14 hours day/night). Earlier flowering was observed under long photoperiod regimes compared with the short photoperiod regimes. Variability was detected among chickpea accessions for their flowering responses when different temperatures were combined with different photoperiods. Earlier flowering was observed under long days (16/8 hours day/night) coupled with high to moderate temperature regimes (24/16 ºC and 20/12 ºC, day and night respectively) compared to short-days (10/14 hours day and night) and moderate to low temperature regimes (20/12 ºC and 16/8 ºC day and night, respectively). Those chickpea accessions such as ICC 6821 and ICCV 96029 which originated from the lower latitudes of Ethiopia and India, respectively, flowered earlier compared to accessions such as CDC Corinne and CDC Frontier which originated from the higher latitudes and cooler temperate environments of western Canada. Photoperiod sensitivity phases were detected in chickpea accessions adapted to the cold environments of western Canada, whereas no photoperiod sensitivity phase was identified in the extra-early flowering cultivar ICCV 96029. The duration of the photoperiod sensitive phase in the chickpea accessions was longer under short days compared to long days. Field and growth chamber evaluation of a chickpea RIL population (CP-RIL-1) revealed the presence of variability among the lines and the two parents for their days to flowering and level of resistance to ascochyta blight. Broad sense heritability across different site-years for days to flower 0.45 to 0.78, plant height 0.48 to 0.78, ascochyta blight resistance 0.14 to 0.68, days to maturity 0.26, photoperiod sensitivity 0.83 and nodes number of first flowering 0.37 to 0.75 were estimated. Days to flower and photoperiod sensitivity were significantly r = -0.21 to -0.58 (P ≤ 0.05 to 0.001) and -0.28 to -0.41 (P ≤ 0.01 to 0.001), respectively and negatively correlated with ascochyta blight resistance in the CP-RIL-1 population. A genetic linkage map consisting of eight linkage groups was developed using 349 SNP markers. Seven QTLs were identified for days to flowering under growth chamber and field conditions on chromosomes 3, 5, 6 and 8 each and 3 QTLs on chromosome 4. The total phenotypic variation explained by QTLs for days to flowering ranged from 7 to 44%. Two QTLs for days to maturity were identified on chromosomes 3 and 8. Three QTLs, one each on chromosomes 3, 4 and 5 were identified for photoperiod sensitivity. The total phenotypic variation explained by each QTL for photoperiod sensitivity ranged from 7 to 41%. A total of three QTL for node of first flowering, one on chromosomes 3 and 8 each, and two on chromosome 4 were identified. The two QTL on chromosome 4 explained total phenotypic variations of 11 and 32%, respectively. Ten QTLs distributed across all chromosomes, except chromosomes 2 and 5, were identified for ascochyta blight resistance. The phenotypic variability explained by each QTL for ascochyta blight resistance ranged from 7 to 17%. The molecular markers associated with these QTLs have potential for use in chickpea breeding.