Pea plants (Pisum sativum cv. Dark Skin Perfection) were grown in a controlled-environment at 25°C day and 15°C night temperature and were then transferred to various high temperature environments. These environments were 32°, 35° and 38°C day temperature with 22°, 25° and 28°C night temperatures respectively. Sample plants were taken at three weeks after planting before transfer to high temperature; and after 1, 10, 100, 1000 minutes and 6 days of exposure to high temperature. The sample plants were analysed for total, organic, inorganic and lipid phosphorus. Growth measurements were also taken. There were no significant changes in the concentrations of organic, lipid and total phosphorus and of inorganic phosphorus except at 6 days exposure to high temperature at which time there was a marked increase in the concentration of inorganic phosphorus. Transfer of plants from the cooler environment to the warmer environments, generally resulted in shorter internode lengths and overall shorter plant height. / Land and Food Systems, Faculty of / Graduate

Plicatic acid and 5-isopropyltropolone, which are found in the heartwood of western red cedar (Thuja plicata, Donn), are known chelators of copper. A study has been made of their effects on some aspects of copper metabolism in rats and mice. As a basis of comparison similar experiments were carried out using penicillamine (PEN), a chelating agent with wide clinical use. In the experiments the sodium salt of 5-isopropyltropolone (T-Na) and the potassium salt of plicatic acid (P-K) were used. When administered daily, P-K and PEN caused an increase in urinary and fecal excretion of copper in rats on a normal diet and an increase in the level of copper in the liver and kidney and a decreased level of copper in the heart and brain. The increased urinary excretion is much more marked with PEN than with P-K. T-Na administered daily had no effect on the excretion of copper in rats on a normal diet and causes a rise in copper content of liver and kidney and a lowering of copper content of heart and brain. It appears that the copper level elevation in kidney and liver caused by P-K and PEN is due to an increased utilization of the routes of excretion while the increased level due to T-Na is probably due to deposition in the cells. When these compounds are administered daily to copper-fed rats similar observations were made with the difference that in organs where copper levels are increased the increases are greater and in organs where copper levels are decreased the decreases are smaller. With T-Na there is one marked difference in that the copper level in the brain is increased. It is felt that this increase is due to a greater penetrating ability of the T-Na-copper chelate because of its lipid solubility. P-K and PEN have very little effect on the toxicity of a single large dose of copper. Earlier experiments with T-Na showed that when T-Na is given shortly after a single large dose of copper the toxicity is greatly increased. The explanation of this is very likely that T-Na increases the penetration of the copper into the CNS and it is here that the toxic effect is exerted. It is felt that this is due to a solubility factor, T-Na and its chelate being lipld-soluble and P-K, PEN and their chelates being water-soluble. When T-Na, P-K and PEN are given to rats in small daily doses over a long period, the atria from such rats exhibited a reduced chronotropic response to tyramine. If at the same time as the rats are being given the chelating agent, they are given excess copper in drinking water the tyramine response remains close to normal. In this regard T-Na possesses the most activity. These observations support the theory that chelating agents inhibit dopamine-β-hydroxylase by rendering copper inaccessible to the enzyme and that subsequent to this inhibition the biosynthesis of the catecholamines is inhibited at the dopamine stage preventing the formation of norepinephrine and epinephrine. As the levels of endogenous norepinephrine and epinephrine fall, the result is a reduced tyramine response. If T-Na, P-K, PEN and D-Na are given in a large single dose the inhibition of dopamine-β-hydroxylase is not evident while it appears that COMT may be being inhibited. / Medicine, Faculty of / Anesthesiology, Pharmacology and Therapeutics, Department of / Graduate

Cation sensitive glass microelectrodes were inserted into single striated muscle fibers of the giant barnacle, Balanus nubilus, to measure directly the activities of sodium and potassium in the myoplasm. The total sodium and potassium content of the individual experimental fibers was determined by flame photometry. From these measurements, the percentage of sodium in the fiber which did not affect the microelectrodes and the percentage of water in the fiber which was not available to act as solvent for the potassium ions were calculated. The minimal percentages of "bound" sodium and water were 84% and 42% respectively. It was hypothesized that a significant fraction of this "bound" sodium was involved in ion pair formation with carboxyl moieties on the myosin molecules which comprise the thick filaments, and experiments were designed to test this hypothesis. In the second series of experiments, the activities of sodium, potassium and hydrogen in the myoplasm were measured as the temperature of the solution bathing the fibers was increased from 7 to 40°C. An irreversible shortening occurred in all fibers between 37 and 40°C. When the fibers shortened in a sodium free Ringer solution, the mean activity of sodium increased by 130%, the mean activity of potassium remained relatively constant, and the pH decreased from 7.17 to 6.77. These experiments provided strong evidence that sodium is bound to myosin in the living fiber, for extracted myosin is known to denature at 37°C and release its associated alkali metal cations. In the third series of experiments, the optical density, O.D., of the single striated muscle fibers was measured at 50 mµ intervals between 450 and 850 mµ. At all wavelengths, the O.D. decreased markedly when the normal Ringer bathing solution was replaced by sodium free sucrose Ringer. For example, at 850 mµ the O.D. of the fibers, relative to the initial value in normal Ringer, decreased from 1 to 0.21 ± 0.06 in 25 minutes. The corresponding increase in the transmittance, T, (O.D. = -log T) was from 5% to 55%. This change in O.D. could be reversed by returning the normal Ringer bathing solution to the bath. Large, reversible decreases in O.D. were also observed when potassium and tris were used as substitutes for sodium. These changes in O.D. are explained by the theory of light scattering if it is assumed that sodium is bound to the main scattering centers in the myoplasm, the thick filaments. When the fibers were bathed in sodium free, lithium substituted Ringer, a small reversible increase in the O.D. was observed, which may indicate that lithium is complexed more strongly than sodium to the binding sites on the thick filaments. In the final series of experiments, the number of sodium and potassium ions "bound" to the contractile proteins in a glycerinated fiber was measured. The free concentrations of hydrogen, sodium and potassium were maintained at values similar to those found in an intact fiber. The results indicated that substantial binding of both sodium and potassium occurred, and that proportionally more sodium than potassium ions were "bound". If the results are extrapolated to the intact fiber, they imply that about as much sodium is "bound" to the contractile proteins as is free in the myoplasm. This amount of "bound" sodium is sufficient to explain the results of the denaturation and light scattering experiments, but insufficient to account for the anomalously low activity of sodium in the myoplasm, as measured by a sodium sensitive microelectrode. Thus, it was concluded that either some factor must enhance the binding of sodium to the contractile proteins in a living cell, or that sodium must be sequestered in organelles which are destroyed by the glycerination process. / Medicine, Faculty of / Graduate

The acetohydroxy acid synthetase levels in streptomycin-sensitive, -dependent and -resistant mutants have been studied in four different strains of Escherichia coli. The activity of the ∝-acetolactate-forming system was found to be greater both at pH 6.0 and at pH 8.0 in streptomycin-dependent mutants than in the corresponding streptomycin-sensitive cultures. In general, streptomycin-resistant mutants demonstrated enzyme activities within the range found for streptomycin-sensitive organisms regardless of whether they were grown in the presence or absence of antibiotic. The acetohydroxy acid synthetase activity of streptomycin-sensitive and -resistant revertants was observed to be lower than that of the dependent Escherichia coli culture from which they were derived by back-mutation. Mutation to streptomycin-resistance or -dependence had no effect on glucokinase and glutamic dehydrogenase activities. The addition of the coenzyme flavin adenine dinucleotide to the incubation mixtures markedly stimulated the activities of all the extracts. This enhancement of acetohydroxy acid synthetase activity had little or no effect on the ratio of activities of this enzyme in the dependent and sensitive Escherichia coli strains investigated. ∝-Acetohydroxybutyrate formation was found to be greater in extracts from the streptomycin-dependent organism than in extracts prepared from the same strain of sensitive and resistant Escherichia coli. The degree of elevation of ∝-acetohydroxybutyrate paralleled that of ∝-acetolactate formation in the dependent mutant. It was concluded from these observations that excretion of L-valine by streptomycin-dependent Escherichia coli was a consequence of the elevated acetohydroxy acid synthetase activity of these mutants. In the dependent organism, it was postulated that streptomycin functioned as a wde-repressorw of acetohydroxy acid synthetase thus permitting the biosynthetic pathway leading to L-valine to serve as an important route of pyruvate dissimilation. / Medicine, Faculty of / Biochemistry and Molecular Biology, Department of / Graduate

The non-phosphorylated oxidative pathway of glucose dissimilation has been confirmed in Pseudomonas aeruginosa using whole cells and cell-free extracts. The oxidation of glucose to 2-ketogluconate was complete and stoichiometric in cell-free extracts and cell-free extracts of glucose grown cells were shown to be incapable of metabolizing 2-ketogluconate. It was shown that whole cells completely degraded 2-ketogluconate and quantitatively accumulated pyruvic acid in the presence of specific inhibitors. The initial step involved in 2-ketogluconate dissimilation was found to be exceptionally labile to the effects of a variety of metabolic inhibitors. The metabolism of 2-ketogluconate was demonstrated to involve the initial phosphorylation with adenosine triphosphate (ATP) as the phosphate donor. The resultant intermediate, 2-keto-6-phosphogluconate, was identified and was shown to undergo reduction by a nicotinamide adenine dinucleotide phosphate linked reductase to 6-phosphogluconate which, in turn, was metabolized to pyruvate by enzymes of the Entner-Doudoroff pathway. Radioactivity from 2-ketogluconate-C¹⁴ was rapidly incorporated into cellular constituents, primarily protein, by washed cell suspensions of P. aeruginosa, but oxidation of 2-ketogluconate did not involve the accumulation of keto-acid intermediates. The role of 2-ketogluconic acid as a key intermediate for the conservation of excess carbon under conditions where nitrogen is limiting was discussed. / Land and Food Systems, Faculty of / Graduate

The changes in the level of circulating thyroid hormone, or protein-bound iodine (PBI), in the male Holstein calf and the Wistar Albino rat during a portion of the growth period have been determined. Two levels of nutrition were employed.in each case to determine if the nutritional status exerted an appreciable effect on the measured PBI level. Repetitive measurements of the serum PBI were conducted with each of eight calves in order to assess age changes, while with the rats single determinations were made on animals killed at regular weight intervals. Carcass analysis of the rats, including body fat and water determinations of the individual animals, and protein and ash analysis of a pooled sample from each group, was conducted with the intent of relating age changes of the serum PBI to a measure of "metabolically active tissue". The PBI level of the Holstein calf was found to increase with age in the growth interval considered. The rate of change of the PBI level of the low plane calves appeared to be less than in the high plane animals; the degree of variability was such, however, that a definite effect of nutrition could not be shown. No correlation was found between either the initial PBI level or the level at slaughter and the daily rate of gain. The resting metabolic rate of the calves was determined prior to the removal of a blood sample for PBI analysis. No relationship between the serum PBI level and the metabolic rate existed. In the case of the rats, no correlation was found between the serum PBI level and chronological age, body weight or fat-free body weight. A great deal of variability of the PBI level among animals in the same group was observed. Possible reasons for this variability are discussed. The body composition data of the high plane rats followed accepted trends, with the body water, protein and ash fractions exhibiting differential growth with respect to body weight and fat-free body weight. The composition of the low plane rats was not appreciably different from that of the high plane animals at equal body weights. The realimentation period was characterized by the deposition of large quantities of body fat. The significance of these findings in terms of the results of other investigators is discussed. Various workers have attempted to relate the serum PBI level of a young animal with its potential productive worth. No evidence was obtained in this study of such a relationship; a discussion of the many factors affecting the serum PBI level is offered to support the contention that no such relationship should be anticipated. / Land and Food Systems, Faculty of / Graduate

The purpose of this study was to examine the effects of exercise of short duration, and the effects of re-exercise on carbohydrate metabolism. I feel that the levels of severe exercise studied approximate the levels of severe exercise which a rainbow trout probably experiences in its natural environment. The level of blood lactate, blood hemoglobin, muscle lactate, muscle glycogen, and liver glycogen were determined in unanesthetized, intact, one and one-half year old rainbow trout acclimated to 10.5°C. Samples were taken immediately after exercise of 3 seconds to 5 minutes, after recovery of 3 minutes to 60 minutes, and after re-exercise of 3 seconds to 5 minutes. The results indicate that exercise of even the shortest duration studied causes an immediate increase in the level of blood lactate, muscle lactate, and blood hemoglobin. Exercise also causes an immediate decrease in muscle glycogen, but does not cause a change in the level of liver glycogen. Changes during the 60 minute recovery period are slight. In general, the effects of re-exercise after a 60 minute recovery period are additive. A correlation analysis between muscle glycogen and muscle lactate indicates that there is a source of muscle lactate other than muscle glycogen at exercise levels of long duration. The source of this muscle lactate does not appear to come from liver glycogen. The energy may be supplied by catabolism of protein or lipid, or by absorption of foodstuffs from the gut. This study provides evidence that rainbow trout are not well adapted for recovery from severe exercise of short duration. / Medicine, Faculty of / Cellular and Physiological Sciences, Department of / Graduate

The lower British Columbia mainland waterways are inhabited by two races of the prickly sculpin Cottus asper Richardson. One race lives in the lower part of rivers or in estuaries and spends at least part of its life, particularly during the spawning season, under tidal influence. This race is the "coastal". The other race, called "inland", is confined entirely to fresh water where it is found in scattered, more or less isolated populations. By investigating the effects of ambient salinity on the oxygen consumption and on the utilization of injected radioiodine, it was found that salinity profoundly effects the iodine metabolism and, to a lesser degree, standard metabolic rates of the fish. In fresh water the thyroids of both races appear relatively quiescent but with increasing salinity, particularly in hyperosmotic environment, there is a marked increase in thyroid uptake of tracer iodine and also in the levels of circulating thyroid hormone. The inland fish demonstrate a greater ability than coastal fish to retain iodide in fresh water, and in sea water their thyroids appear more active. The inland fish also have a lower oxygen consumption in fresh water than do coastal fish. Viewed together, the results lead to the conclusion that the inland fish, with respect to their osmoregulating ability, show genetic divergence from the coastal forms. The latter probably more closely resemble the ancestral form. / Science, Faculty of / Zoology, Department of / Graduate

The concentration of glycolytic intermediates and co-factors in and pH values of P. superficlalis muscles from each of five 15 week-old and five 25 week-old White Cannon torn turkeys was measured at varying times between 0 and 180 min. post-mortem. Different rates of post-mortem glycolysis were evident among birds, independent of age. On the basis of ATP catabolism, pH and lactic acid accumulation, two groups categorized as "fast-" and "slow-glycolyzing" were evident. The different rates of glycolysis could not be explained by qualitative or quantitative differences in control of the glycolytic flux. The patterns of change in concentration of intermediates and co-factors expressed as mass action ratios suggested that regardless of glycolytic rate, post-mortem glycolysis in turkey breast muscle is susceptible to control at the reactions catalyzed by hexokinase, phosphofructo kinase, aldolase and triosephosphate isomerase, glyceraldehyde phosphate dehydrogenase and phosphoglycerokinase and pyruvate kinase. P. superficialis muscles from six 19 and six 27 week-old White Cannon torn turkeys were analyzed for ATP concentration at "0" and "60" min. post-mortem and muscle pH was determined during a three hour post-mortem period. The time required for excised muscle strips to achieve maximum contraction was determined by periodic measurement of strip length. Analysis of the data indicated a relationship between rate of ATP catabolism and time to maximum contraction. "Slow-" and "fast-glycolyzing" groups were evident and were independent of age. The "slow-glycolyzing" group had a higher initial ATP concentration, a larger proportion of initial ATP remaining at 60 min. and required a longer time for the muscle strips to achieve maximum contraction. / Land and Food Systems, Faculty of / Graduate

Six male and six female chinchilla (Chinchilla lanigera) in the late phase of growth were used to study the effects of sex, crude protein level in the ration and duration of experiment on body weight gains, digestibility of energy, dry matter, organic matter and protein and efficiency of protein utilization, as measured by biological value and net protein utilization. Two isocaloric rations of differing crude protein content (16.25% and 19.56%) were supplied ad libitum for three one-week experimental periods. The results showed that female chinchilla had significantly (P<0.05) greater body weight gains than males after adjustment for initial body weight and feed intake. There was a significant (P<0.05) effect of ration on the digestibility coefficients studied. The mean apparent digestibility coefficients for energy, dry matter, organic matter and protein for ration 1 (16.25% crude protein) were 65.09, 66.44, 67.73 and 62.83%, respectively; while for ration 2 (19.56% crude protein) the values were 67.32, 68.52, 70.21 and 73.23%, respectively. On the other hand, sex had no significant (P<0.05) effect on digestibility. There was a significant (P<0.05) effect of ration on the protein utilization indices studied. Biological value was not significantly (P<0.05) different for the two rations. The mean values for biological value and net protein utilization for ration 1 (16.25% crude protein) were 66.38 and 42.02%, respectively; while for ration 2 (19.56% crude protein) the values were 66.96 and 48.17%, respectively. On the other hand, sex had no significant (P<0.05) effect on protein utilization. The sensitivity of growing chinchilla to protein quality suggests a major role for prececal digestion and absorption although this does not preclude the synthesis and subsequent breakdown of microbial protein in the postcecal part of the gut. / Land and Food Systems, Faculty of / Graduate