Köln, Universiẗat, Diss., 2003.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第13851号 / 工博第2955号 / 新制||工||1436(附属図書館) / 26067 / UT51-2008-C767 / 京都大学大学院工学研究科合成・生物化学専攻 / (主査)教授 濵地 格, 教授 森 泰生, 教授 白川 昌宏 / 学位規則第4条第1項該当

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第17599号 / 工博第3758号 / 新制||工||1573(附属図書館) / 30365 / 京都大学大学院工学研究科合成・生物化学専攻 / (主査)教授 濵地 格, 教授 梅田 眞郷, 教授 杉野目 道紀 / 学位規則第4条第1項該当

2 p. / Grain yield, test weight, and other characteristics of barley, durum, and wheat varieties are provided in this publication. Revised 2017, Previous version10/2016. Previous version 10/2015.

2 pp. / Grain yield, test weight, and other characteristics of barley, durum, and wheat varieties are provided in this publication.Revised 10/2016. Previous version 10/2015.

A significant number of proteins function as multimeric structures, most commonly as dimers. One of the primary mechanisms by which proteins evolve is through gene duplication and mutations of the resulting duplicated gene. The evolution of dimeric proteins after gene duplication is of interest because it can form three types of dimer: two homodimers and a heterodimer. Point mutations that occur in the interface of dimers would affect their binding strength and might change their path in the evolution. Here we designed an evolutionary model for protein dimerization after gene duplication. In this work, we have used dimers' PDB structures to construct the network of contacts between amino acids in the interface. Several pairwise energy contact matrices were examined to find reasonable interface binding energies. Using the population genetics theory, we defined a selection criteria based on dimer interface strength and let them evolve as the mutations happen. We observed that the dimer structures are bound to be in the mostly homodimer state or mostly heterodimer state, and there are few occasions that we have all three types of structures as strong dimers. We anticipate three fates for the dimer protein's evolution after gene duplication, neofunctionalization, subfunctionalization, and loss of the gene. A loss of function in homodimer structures might eventually lead to a subfunctionalization since the two interfaces are different. On the other hand, if a heterodimer loss happens, we would have two strong homodimer structures so both neofunctionalization and subfunctionalization might still happen. In the first case, one could gain a new function while the other homodimer performs the protein's old function. In the latter case, the two separate homodimers could each assume different parts of the full function of the original gene (which is the definition of subfunctionalization). / Thesis / Master of Science (MSc) / A large fraction of proteins are found to exist as dimers composed to two identical subunits. If the gene for the single subunit is duplicated, three types of dimers can emerge, two homodimer structures and a heterodimer structure. Gene duplication is a major driving force of evolution as it can allow the proteins to perform new tasks. Here we define a model to understand the evolution of dimeric proteins as they undergo mutations in their interface, changing their stickiness to each other. We find that evolution favours the dimers to either be homodimer or heterodimer, but not both at the same time. When there are two homodimers, one of them can acquire a new function (which is known as neofunctionalization). When there is a heterodimer, both genes are now required to do the orginal job of a single gene (which is known as subfunctionalization). These mechanism provide two possible reasons why the duplicate gene cannot subsequently be deleted from the genome.

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The dietary protein requirements of endurance trained athletes have been previously shown to be higher or no different than those of sedentary persons. However, the current Canadian Recommended Nutrient Intake (RNI) for protein contains no allowance for the effects of habitual physical activity. The discrepancy as to whether the protein requirements of active individuals are elevated, is probably due to: varying study designs, the different training status of the subjects, dissimilar exercise intensities, and the dietary condition of the subjects studied. In addition, previous work (Tarnopolsky, LJ et al. J. Appl. Physiol. 68(1):302-308, 1990), has shown that males may catabolize an increased amount of protein, as a result of endurance exercise, compared to females. The present study examined protein turnover in trained male (n=6) and female (n=6) endurance athletes (runners) • Athletes were selected for equal training status and conditioning and were placed on a diet, isoenergetic with their habitual intake, containing protein at the Canadian RNI. All female athletes were tested during the mid-follicular phase of their menstrual cycle. After being adapted to the diet for 10 days during which the athletes exercised according to their habitual exercise schedule, each athlete completed a three day measurement of nitrogen balance. Nitrogen balance showed that the RNI was inadequate for the female athletes (mean± SE), nitrogen balance= -0.89 ± 0.33 g N·d⁻¹ (-15.9 ± 6.0 mg N·kg⁻¹·d⁻¹), and for male athletes, nitrogen balance = -1.69 ± 0.64 g N·d⁻¹ (-26.3 ± 11.0 mg N·kg1·d⁻¹). To examine the kinetics of leucine metabolism during exercise, each subject received a primed constant intravenous infusion of L-[1-¹³C]leucine while resting for 2.0 hand then during a 90 minute treadmill run at approximately 65% of VO₂ₘₐₓ. Blood samples were taken at steady state and analyzed for ¹³CO enrichment of a-ketoisocaproic acid and expired gas samples were analyzed for ¹³CO₂ enrichment. Corrections were made for changes in background ¹³CO₂/ ¹²CO₂ and changes in bicarbonate retention factor, during exercise, were also determined. Measurements of whole-body leucine kinetics (flux, oxidation, and non-oxidative leucine disposal) were calculated using the reciprocal pool model. Exercise resulted in a significant increase (P<O. 001) in leucine oxidation in both males and females. The increase was 95% above resting in females and 84% above resting in males. Male athletes oxidized a greater amount of leucine during the infusion than female athletes (P=O. 004). Leucine flux increased significantly (P<O. 001) during exercise in both groups of athletes. The non-oxidative portion of leucine flux did not change significantly throughout the infusion in either male or female subjects. Oxidation of leucine could account for 88% of the negative nitrogen balance in the female athletes and 90% of the negative nitrogen balance in the male athletes. It is concluded that the Canadian RNI for protein is inadequate for those persons who continually engage in endurance activities. In addition, leucine oxidation during prolonged sub-maximal exercise is greater in males than females and the increase in amino acid oxidation could account for approximately 90% of the negative nitrogen balance observed in these groups of athletes. Future investigations of protein requirements for athletes should consider males and females as distinct groups. / Thesis / Master of Science (MSc)