Biological Sciences - Theses, Dissertations, and other Required Graduate Degree Essays

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Methylmercury uptake from water and food by aquatic organisms from different trophic levels. --

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
1974
Document type: 
Thesis
File(s): 
Senior supervisor: 
G.H. Geen
Department: 
Science: Department of Biological Sciences
Thesis type: 
Thesis (M.Sc.)

Effects of environmental and physiological factors on the acoustic behavior of Aedes aegypti (L.) (Diptera: Culicidae). --

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
1974
Document type: 
Thesis
File(s): 
Senior supervisor: 
P. Belton
Department: 
Science: Department of Biological Sciences
Thesis type: 
(Dissertation) Ph.D.

A study of the pancreatic islets and zinc toxicity in the rainbow trout, Salmo gairdneri Richardson

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
1980
Document type: 
Thesis
File(s): 
Senior supervisor: 
B.A. McKeown
Department: 
Science: Department of Biological Sciences
Thesis type: 
Thesis (M.Sc.)

Genetic studies on the gene coding for paramyosin in Caenorhabditis elegans unc-15 and the adjacent region

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
1979
Document type: 
Thesis
File(s): 
Senior supervisor: 
D.L. Baillie
Department: 
Science: Department of Biological Sciences
Thesis type: 
(Dissertation) Ph.D.

The effects of water temperature on oviposition and other aspects of the life history of Aedes Aegypti (L.) and Culex Pipiens L.

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
1978
Document type: 
Thesis
File(s): 
Senior supervisor: 
P. Belton
Department: 
Science: Department of Biological Sciences
Thesis type: 
Thesis (M.Sc.)

Hydrostatic pressure in relation to the synchronous culture of algae in open and closed systems.

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
1968
Abstract: 

Chlorella ellipsoidea cultured using conventional methods under a 14: 10 light-dark regime in Bai j eririck ' s medium at 25?+ 1?with 700 ft-c illumination resulted in synchronous division with an n number of 4. Under identical conditions of light intensity, temperature, culture medium, and light-dark regime but in a closed system which was designs to study the effects of hydrostatic pressure on synchronous algae cultures, synchronous cell division did not occur and the n number was 2 or less at 1 atm. The most significant difference in the culture conditions arises because the concentrations of dissolved gases (mainly CCu and O^) remain relatively constant throughout the growth cycle in the open system while the gases vary in concentration continuously during the cycle in the closed system. In the closed system C>2 increases continuously c?CO-p decreases during the light period; the reverse is true in the dark. Analyses of the rati.os of dry weight, protein content, and cell size showed increases of approximately 2 in the closed system and 4 in the open system. The intent of this study was to determine effects of hydrostatic pressure on the physiology and morphology of algae. Therefore it was essential to develop techniques for successful culture in a closed system. Various modifications of culture conditions were made in attempts (only partially successful) to obtain equal growth in the two systems. 11 The effects of variations in some environmental parameters on the n number, dry weight, protein concentration, and cell size in the open and closed systems were investigated. With varied growing conditions of light intensity (15-700 ft--c), light- dark regimes (14: 10, 16: 8, 18: 6, 6: 18, 8: 16, 10: 14), media (Beijerinck, Burr, Sorokin, Tamiya and Morimura, and Beijerinck's modified with bicarbonate), CC^ concentration (0-100% saturation), and the addition of organic substances (glycolate, ascorbate, dithiothreitol) the n number and the ratios of increase in the other growth criteria were 4 in the open system but never more than 2 in the closed system. The n number and ratios of increase in dry weight, protein content and cell size were 4 in the open system at atmospheric Cu concentration but only 2 or less at high 02 (50 and 95%) concentration. These results indicate that high C>2 is probably responsible for the descrepancies in the n number and the rEitios of increase of the other criteria between the open and closed systems. Photosynthetically evolved 0^ in the closed system during the light period appears to be sufficient to induce this Warburg Effect. It was hypothesized that the Warburg Effect is responsible for the observed differences in increases in the growth criteria in the open and closed systems. Experiments were carried out to determine if photosynthetically evolved 02 was inhibiting cell growth. Using the Biological Oxygen Monitor algal samples were exposed to ? concentrations varying from 0 to 100% saturation at 25?with 700 ft-c Ill illumination. On the basis of these results which have indicated a decrease in the relative rates of O^ evolution at high 02 concentrations, it was concluded that Op evolved in the closed system could be responsible for the inhibition of photosynthesis. Synchronous growth under pressure has not yet been obtained. However, pressure effects on cell division were investigated. The n number was 4 in cells dividing while exposed to pressures of up to 200 atm, but pressures above 335 atm completely inhibited cell division. A possible mutagenic effect of pressure exposure on algal cells was considered.

Document type: 
Thesis
File(s): 
Senior supervisor: 
William Vidaver
Department: 
Science: Department of Biological Sciences
Thesis type: 
(Dissertation) Ph.D.

Uptake and evolution of carbon dioxide during photosynthesis : a survey of plant divisions.

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
1968
Abstract: 

The exchange of CO2 in light was studied in plants of six divisions. The rates of CO2 uptake in light, of CO2 evolution in darkness, and the concentration of CO2 at C02 compensation point were measured in a closed system with an infrared gas analyser. The CO2 evolution rate in light was then calculated from these measurements. Rates of C02 exchange and CO2 compensation points were similarly measured at several concentrations of oxygen between 2% and 100%. The CO concentration at CO compensation point was a linear function of O2 concentration in eleven of the twelve species studied. The CO2 compensation point of corn was not affected by O2 . At 60% O2, the inhibition of rates of CO2 uptake was of the same magnitude in all species studied. The minimum rate of CO2 evolution in light was found to be at least twice the rate of CO2 evolution in the dark in ten of eleven species.

Document type: 
Thesis
File(s): 
Senior supervisor: 
C.D. Nelson
Department: 
Science: Department of Biological Sciences
Thesis type: 
(Thesis) M.Sc.

Light and electron microscope investigations of the germination of Lactuca sativa L. embryos

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
1967
Abstract: 

The structure of Lactuca sativa Ij. embryos was studied using light and electron microscopy. Dry embryos and seedlings ranging from 12 to 108 hrs. old were examined. Material for light microscopy was fixed in 10% acrolein and embedded in glycol methacrylate. Material for electron microscopy was fixed in glutaraldehyde and post-fixed in osmium tetroxide; it was embedded in araldite-DDSA. In general, cells of dry embryos are filled with reserve proteins and lipids. Nuclei, mitochondria, ribosomes, and some membranes appear to be only slightly changed by their dehydrated state. Plastids and the endoplasmic reticulum are less well-defined and other organelles are absent from the dry embryo. Variations in the structure of the plastids and the protein bodies suggest differences in the degree of dormancy of different parts of the embryo. Reactivation of cells begins just behind the root apex and progresses through the hypocotyl and acropetally in the cotyledons. Changes in the structure of organelles and reserve materials are described. Plastids undergo the most marked changes. Cells of the root tip, hypocotyl, and cotyledons each have a characteristic type of plastids.

Document type: 
Thesis
File(s): 
Senior supervisor: 
L. M. Srivastava
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.Sc.

Observations on the growth and physiology of Pinus strobus L. seedlings grown under various conditions of soil moisture and nitrogen and phosphorus nutrition.

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
1967
Abstract: 

PART I White pine seedlings (Pinus strobus L.) were grown at high or low soil-moisture levels. The leader stem length, fresh weight of the seedlings, respiration, photosynthesis, transpiration, translocation of photosynthate from shoots to roots, and bio-electric potentials between the tip and the base of the stem were measured throughout the growing season from April to October. At both moisture levels the lowest translocation of recent photosynthate from shoots to roots occurred during early summer, or at the time when the rate of root growth was the lowest and that of the shoot the highest. During 14 early summer the specific activity of CC>2 respired by the shoots of such plants remained high throughout an 8 h experimental period, indicating a continuous utilization of recent photosynthate as a respiratory substrate. On the other hand, early and late in the growing season, when translocation of recent photosynthate from shoots to roots and the rate of root growth were high, the specific activity 14 of CO- respired by the shoots rapidly decreased during the ^ 8 h experimental period, indicating a drop in the utilization of recent photosynthate as respiratory substrate. The highest positive values for the potential difference between the top and the base of the main shoot also occurred in early summer or during the period of high rates of i canspiration. PART II Potted white pine (Pinus strobus L.) seedlings were grown on media containing different amounts of nitrogen (N) and phosphorus (P). The seedlings were grown either in controlled environment chambers or outdoor cold frames. Following periods of five, seven and thirteen weeks on treatment the seedlings were analyzed to determine rates of respiration, photosynthesis and the degree of translocation of recent photosynthate to the roots. Shoot and root fresh weights were recorded. Analyses were made to determine the metabolic fate of the translocated sugars. The best overall growth and the highest root/shoot ratios were found in seedlings receiving intermediate levels of N and P. The range of nutritional conditions employed was found to have no effect upon rates of shoot and root respiration or photosynthesis, even after thirteen weeks of treatment. Lateral root formation was depressed under conditions of high N and P. Mycorrhizal abundance showed a maximum at intermediate levels of nutrients. Translocation of recent photosynthate to the roots was depressed by high P, this depression was however, reversed to some extent by increasing N levels. The hydrolysis of sucrose recently translocated to the roots was increased with increasing N supply. The resultant hexoses being metabolised to amino and organic acids. However, sucrose continued to be the dominant form in which VI 14 recently translocated C occurred in the roots. High levels of P reduced the effect of N on the metabolism of translocated sucrose. Relatively very few of the metabolically active compounds, isolated from the soluble fraction of the roots, showed distinct patterns of change which could be correlated to either the different nutritional levels of N and P supplied or to the incidence of mycorrhizae.

Document type: 
Thesis
File(s): 
Senior supervisor: 
C.D. Nelson
Department: 
Science: Biological Sciences
Thesis type: 
(Dissertation) Ph.D.

An approach to the study of the physiological control of translocation in higher plants.

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
1967
Abstract: 

Tne elective or tnis -nvestiga^icn v/a^ to ?'-,?ai.'. __.e insight into wnat limits or cor.trc^ transl^catior. i:" hi /. ~ plants. ?/ Photosynthesis and trans location xv^r^ studied v..,_.'.-v ^""CO.-,. Over 75% of the assimilated ~ c W?s incorporated into surcro~e via aspartic acid and malic acid. About 20% cf the "^C v.vnt _..tc ethanoi-insoluble compounds. Lowering the temperature to o" '?? ?delayed the incorporation of the ^ ""C i^to sucrose, out hac. little effect on the rate or amount of incorporation. In young corn plants all the leaves exported C, most of which went to the roots and the growing regions of the plants. Ail the leaves imported some 14G assimilated in other leaves. The only translocated organic compound in corn was sucrose-It was translocated down the leaf blade at a velocity in excess of 150 cm hour . The transiocation profile in the leaf blade v/as logarithmic and was found to be due to a reversible accumulation of t;.e translocate in the vascular tissue. Corn leaves were used to establish a method for measuring 14 transiocation from the leaf. Measuring the amount of C remaining in the fed area of leaf at various times after feeding ""^2 provided information on 3 characteristics of translocaticn; the relative rate of transiocation from the leaf, the total percentage of the assimilated C that is translocated, and the turnover time of the transiocation pool. From these measurements the transioca- tion in corn at 2600 ft-c was calculated to be 327 ugm of sucrose -2 -i d.;. mm . The turnover time of the transiocation pool in corn v,-_s 80 minutes. This method was used to study the effect of different factors on transiocation from the leaf. A decrease in te:..oari.tu.^ decreased the rate of translocation more or less linearly from 26 to 7? The turnover time of the translocation pool and the percentage of the assimilates translocated increased with a decrease in temperature. Light had no significant effect on translocation. The rate of translocation and the percentage of the assimilates translocated changed with the age of the leaf. The method of measuring the C remaining in the fed area of leaves was used in a comparative study of translocation in a number of species. The relative rate of translocation and the percentage of the assimilates translocated varied with the species. Corn, sorghum, millet and sunflower translocated between 70 and 90% of the assimilated ^C in 24 hours, whereas the other species translocated only between 40 and 60%. The compounds in which the 14C was held back in the leaf varied with the species. The turnover time of the translocation pool divided the species into 2 groups; tomato and radish had a turnover time of 40 minutes, all the other species had a turnover time of about 80 minutes. The result of the investigations suggest that the limiting process in translocation is the transfer of the translocate from the assimilating cells to the phloem. It is speculated that the main part of the control of translocation is at the membranes of the exporting cells.

Document type: 
Thesis
File(s): 
Senior supervisor: 
C.D. Nelson
Department: 
Science: Biological Sciences Department
Thesis type: 
(Dissertation) Ph.D.