A relationship between photosynthesis and translocation in plants stressed by ionizing radiation

Since previous investigations have shown that low levels of ionizing radiation can induce a reduction in the rates of apparent photosynthesis and in the magnitude of photoassimilated l4C exported out of a leaf, the present studies were designed and conducted to determine the relationship, if any, between the radiation effects on these two physiological processes. The experiments were particularly designed to determine if the radiation-induced reduction in export is the result of the reduction in photosynthesis and hence availability of materials for translocation or the result of a reduction in the amount of energy available for the vein loading process. This study has shown that the radiation-induced reduction in l4C export out of a leaf is likely related to a loss of energy available for the vein loading process rather than a reduction in the supply of materials available for export due to reduced C02 uptake. The process of photophosphorylation was shown to be reduced by exposure to radiation to an extent similar to the reduction in the export of l4C which was also observed. Both of these processes returned to their pre-irradiation rates 120 minutes following radiatruon exposure. The rate of photosynthetic C02 uptake was also reduced by radiation exposur~ howeve~ this process did not return to the control level nor was the extent of reduction as large as observed for photophosphorylation and photoassimilate export. The observed relationship between the reductions of export and photoph~sphorylation pointed to the utilization of photosynthetically produced ATP in the vein loading process. The radiation-induced reduction in the export of l4C was observed at the highest light intensity used in this study which would also imply the involvement of the photophosphorylation process as an energy seurce for vein loading. The lack of radiation-induced reduction in export at low light intensities was interpreted as being due to the utilization of respiratory derived ATP, a process known to be insensitive to radiation at the levels used in this study, as the energy source for the vein loading process. Studies using plants not stressed by radiation showed that there was an increase in export of 14C with higher light intensities. In summary, the data has been interpreted as showing that at high light intensities the ATP, produced by photophosphorylation, is available for use in the vein loading process. The site of ATP utilization could not be determined from the data obtained in this study but possible sites have been indicated from the work done by other physiologists and are discussed in the thesis.

A speculative systems model of the dynamic interaction among students, faculty and administration in the community college, with particular reference to intrinsic motivation and the teacher-administrator interface

The challenge the community college faces in helping meet the needs of the living open system of society is examined in this study. It is postulated that internalization student outcomes are required by society to reduce entropy and remain self-renewing. Such behavior is characterized as having an intrinsically motivated energy source and displays the seeking and conquering of challenge, the development of reflective knowledge and skill, full use of all capabilities, internal control, growth orientation, high self-esteem, relativistic thinking and competence. The development of a conceptual systems model that suggests how transactions among students, faculty and administration might occur to best meet the needs of internalization outcomes in students, and intrinsic motivation in faculty is a major purpose of this study. It is a speculative model that is based on a synthesis of a wide variety of variables. Empirical evidence, theoretical considerations, and speculative ideas are gathered together from researchers and theoretici.ans who are working on separate answers to questions of intrinsic motivation, internal control and environments that encourage their development. The model considers the effect administrators·have on faculty anq the corresponding effect faculty may have on students. The major concentration is on the administrator--teacher interface.For administrators the model may serve as a guide in planning effective transactions, and establishing system goals. The teacher is offered a means to coordinate actions toward a specific overall objective, and the administrator, teacher and researcher are invited to use the model to experiment, innovate, verify the assumptions on which the model is based, and raise additional hypotheses. Goals and history of the community colleges in Ontario are examined against current problems, previous progress and open system thinking. The nature of the person as a five part system is explored with emphasis on intrinsic motivation. The nature, operation, conceptualization, and value of this internal energy source is reviewed in detail. The current state of society, education and management theory are considered and the value of intrinsically motivating teaching tasks together with "system four" leadership style are featured. Evidence is reviewed that suggests intrinsically motivated faculty are needed, and "system four" leadership style is the kind of interaction-influence system needed to nurture intrinsic motivation in faculty.

An investigation into the effects of homopteran honeydew sugars versus floral nectar sugars on black fly longevity, flight performance and digestion /

Floral nectar is thought to be the primary carbohydrate source for most dipteran species. However, it has been shown that black flies (Burgin & Hunter 1997 a,b,c), mosquitoes (Foster 1995; Burkett et al. 1999; Russell & Hunter 2002), deer flies (Magnarelli & Burger 1984; Janzen & Hunter 1998; Ossowski & Hunter 2000), horse flies (Schutz & Gaugler 1989; Hunter & Ossowski 1999) and sand flies (MacVicker et al. 1990; Wallbanks et al. 1990; Cameron et al. 1992, 1995; Schlein & Jacobson 1994, 1999; Hamilton & EI Naiem 2000) feed on homopteran honeydew as well as floral nectar. Prior to 1997 floral nectar was thought to be the main source of carbohydrates for black flies. However, Burgin & Hunter (1 997a) demonstrated that up to 35% of black flies had recently consumed meals of homo pte ran honeydew. This information has necessitated a re-assessment of many life history aspects of black flies. Attempts are being made to examine the effects of nectar versus honeydew on black fly fecundity and parasite transmission (Hazzard 2003). Recently, Stanfield and Hunter (unpublished data) have shown that in female black flies, honeydew sugars produce flights of longer distance and duration than do nectar sugars. This thesis examines two aspects of black fly biology as it relates to sugar meal consumption. First, the effects of honeydew and nectar on black fly longevity are examined. Second, the proximate causation behind longer flight performances in honeydew-fed flies will be examined. The comparison between these two sources is important because nectar is composed of mainly simple sugars (monosaccharides and disaccharides) whereas honeydew is composed of both simple and complex sugars (including trisaccharides and tetrasaccharides ).

Effect of pH on non-photochemical quenching in spinach photsystem 2 particles as measured by picosecond fluorescence decay kinetics

Single photon timing was used to study picosecond chlorophyll a fluorescence decay kinetics of pH induced non-photochemical quenching in spinach photosystem 2 particles. The characteristics of this quenching are a decrease in chlorophyll a fluorescence yield as well as a decrease in photochemistry at low pH. Picosecond kinetics of room temperature fluorescence temporally resolve the individual components of the steady state fluorescence yield into components that are related to primary energy conversion processes in photosystem 2. Four components were resolved for dark adapted (Fo), light saturated (Fm), and chemically reduced (Nadithionite) photosystem 2 reaction centres. The fastest and slowest components, indicative of energy transfer to and energy capture by the photosystem 2 reaction centre and uncoupled ("dead") chlorophyll, respectively, were not affected by changing pH from 6.5 to 4.0. The two intermediate components, indicative of electron transfer processes within the reaction centre of photosystem 2, were affected by the pH change. Results indicate that the decrease in the steady state fluorescence yield at low pH was primarily due to the decrease in lifetime and amplitude of the slower of the intermediate components. These results imply that the decrease in steady state fluorescence yield at low pH is not due to changes in energy transfer to and energy capture by the photosystem 2 reaction centre, but is related to changes in charge stabilization and charge recombination in the photosystem 2 reaction centre.

An exploration of the experience of implementing the second step violence prevention curriculum in one primary general learning disabilities class /

Violence has always been a part of the human experience, and therefore, a popular topic for research. It is a controversial issue, mostly because the possible sources of violent behaviour are so varied, encompassing both biological and environmental factors. However, very little disagreement is found regarding the severity of this societal problem. Most researchers agree that the number and intensity of aggressive acts among adults and children is growing. Not surprisingly, many educational policies, programs, and curricula have been developed to address this concern. The research favours programs which address the root causes of violence and seek to prevent rather than provide consequences for the undesirable behaviour. But what makes a violence prevention program effective? How should educators choose among the many curricula on the market? After reviewing the literature surrounding violence prevention programs and their effectiveness, The Second Step Violence Prevention Curriculum surfaced as unique in many ways. It was designed to address the root causes of violence in an active, student-centred way. Empathy training, anger management, interpersonal cognitive problem solving, and behavioural social skills form the basis of this program. Published in 1992, the program has been the topic of limited research, almost entirely carried out using quantitative methodologies.The purpose of this study was to understand what happens when the Second Step Violence Prevention Curriculum is implemented with a group of students and teachers. I was not seeking a statistical correlation between the frequency of violence and program delivery, as in most prior research. Rather, I wished to gain a deeper understanding of the impact ofthe program through the eyes of the participants. The Second Step Program was taught to a small, primary level, general learning disabilities class by a teacher and student teacher. Data were gathered using interviews with the teachers, personal observations, staff reports, and my own journal. Common themes across the four types of data collection emerged during the study, and these themes were isolated and explored for meaning. Findings indicate that the program does not offer a "quick fix" to this serious problem. However, several important discoveries were made. The teachers feU that the program was effective despite a lack of concrete evidence to support this claim. They used the Second Step strategies outside their actual instructional time and felt it made them better educators and disciplinarians. The students did not display a marked change in their behaviour during or after the program implementation, but they were better able to speak about their actions, the source of their aggression, and the alternatives which were available. Although they were not yet transferring their knowledge into positive action,a heightened awareness was evident. Finally, staff reports and my own journal led me to a deeper understanding ofhow perception frames reality. The perception that the program was working led everyone to feel more empowered when a violent incident occurred, and efforts were made to address the cause rather than merely to offer consequences. A general feeling that we were addressing the problem in a productive way was prevalent among the staff and students involved. The findings from this investigation have many implications for research and practice. Further study into the realm of violence prevention is greatly needed, using a balance of quantitative and qualitative methodologies. Such a serious problem can only be effectively addressed with a greater understanding of its complexities. This study also demonstrates the overall positive impact of the Second Step Violence Prevention Curriculum and, therefore, supports its continued use in our schools.

Synechococcus sp. PCC 7002 CpcB lyase null mutations alter phycocyanin chromophore function and, consequently, affect the redistribution of excitation energy via the light state transition /

Phycobilisomes are the major light harvesting complexes for cyanobacteria and phycocyanin is the primary phycobiliprotein of the phycobilisome rod. The phycocyanobilin lyases responsible for chromophorylating the phycocyanin p subunit (CpcB) have been recently identified in the cyanobacterium Synechococcus sp. PCC 7002. Surprisingly, mutants missing the CpcB lyases were nevertheless capable of producing pigmented phycocyanin. 10K absorbance measurements revealed that the energy states of the p phycocyanin chromophores were only subtly shifted; however, 77K steady state fluorescence emission spectroscopy showed excitation energy transfer involving the targeted chromophores to be highly disrupted. Such evidence suggests that phycobilin orientation within the binding domain is specifically modified. We hypothesized that alternate, less specific lyases are able to act on the p binding sites. A phycocyanin linker-polypeptide deficient mutant was similarly characterized. The light state transition, a short term adaptation of the photosynthetic light harvesting apparatus resulting in the redistribution of excitation energy among the photo systems, was shown to be dominated by the reallocation of phycocyanin-absorbed excitation energy. Treatment with a high M phosphate buffer effectively prevented the redistribution of both chlorophyll a- and phycobilisome- absorbed excitation energy, suggesting that the two effects are not strictly independent. The mutant strains required a larger redistribution of excitation energy between light states, perhaps to compensate for their loss in phycobilisome antenna function.

National energy policies of the Federal Republic of Germany and Canada in the 1970s and 1980s: are economic and/or environmental concerns responsible for change?

The thesis presents a comparison of the national energy policies of the Federal Republic of Germany and Canada from 1973 until the late 1980s. The purpose of this paper is to analyze whether economic and/or environmental concerns were responsible for changes in the· West-German and Canadian national energy policies. Furthermore, the feasibility of implementing a soft energy path in West-Germany and Canada is examined. For better comprehension of the policy-making process and implemented changes in the national energy policies of the two states, the West-German and Canadian parliamentary systems and the political cultures were compared. For the analysis, several events with international impact were taken as guidelines. Furthermore, based on statistical data, the West-German and Canadian energy production and consumption were analyzed. With reference to these results the degree of the de facto changes in the national energy policies were analyzed. In addition, the thesis discusses the possibilities which a soft energy path offers to both national governments to renounce themselves from the dependencies on a few energy resources. The thesis reveals that changes in the West-German and Canadian national energy policies, in their energy production and consumption are correlated to various world events. In particular, governmental reponses security of energy supply by the two international oil crises of 1973 and 1979/1980 demonstrate that changes in the West-German and Canadian national energy policies were implemented in reaction to economic concerns than environmental ones. With the policies "away from oil" and "off oil", the West-German and Canadian government implemented the i i substitution of oil through various diverse energy supply resources. However, energy savings concepts and policies were initiated through the first oil crisis in 1973. The world recessions in 1975 and 1982 had no 'profound impacts on the agenda of West-German and Canadian energy policies. As a consequence of the stagnation or the negative growth of the world economic market, changes in their energy production and consumption can be perceived. However, the West-German and Canadian energy production and consumption intensified with the augmentation of the world economy. During the period of study, environmental concerns were taken into account in the energy policy agendas of the Federal Republic of Germany and Canada but they were not of primary concern. wi thin the decade of. the 1980s notably more environmental considerations were taken into account in the energy policies of the two states. The two nuclear reactor accidents in 1979 and 1986 sharpened to various degrees West-German and Canadian public discourse of present energy supply mix and attitude towards energy production and consumption. The statistical data reflects yet no changes in the energy policies in regard to the position of nuclear power. However, in the next several years possible changes can be observed through statistical data, because the planning, the construction and possible phase out of nuclear power requires several years. Finally, the thesis reveals that the implementation of a soft energy path requires profound changes in the consumer behaviour. As several studies indicate, a soft energy path is technological and economically feasible for the Federal Republic of Germany and Canada, its implementation remains to be a political decision.

Competing demands for a complex system : photosystem II repair, photoprotection and quantum yield

Photosynthesis in general is a key biological process on Earth and Photo system II (PSII) is an important component of this process. PSII is the only enzyme capable of oxidizing water and is largely responsible for the primordial build-up and present maintenance of the oxygen in the atmosphere. This thesis endeavoured to understand the link between structure and function in PSII with special focus on primary photochemistry, repair/photodamage and spectral characteristics. The deletion of the PsbU subunit ofPSII in cyanobacteria caused a decoupling of the Phycobilisomes (PBS) from PSII, likely as a result of increased rates of PSII photodamage with the PBS decoupling acting as a measure to protect PSII from further damage. Isolated fractions of spinach thylakoid membranes were utilized to characterize the heterogeneity present in the various compartments of the thylakoid membrane. It was found that the pooled PSIILHCII pigment populations were connected in the grana stack and there was also a progressive decrease in the reaction rates of primary photochemistry and antennae size of PSII as the sample origin moved from grana to stroma. The results were consistent with PSII complexes becoming damaged in the grana and being sent to the stroma for repair. The dramatic quenching of variable fluorescence and overall fluorescent yield of PSII in desiccated lichens was also studied in order to investigate the mechanism by which the quenching operated. It was determined that the source of the quenching was a novel long wavelength emitting external quencher. Point mutations to amino acids acting as ligands to chromophores of interest in PSII were utilized in cyanobacteria to determine the role of specific chromophores in energy transfer and primary photochemistry. These results indicated that the Hl14 ligated chlorophyll acts as the 'trap' chlorophyll in CP47 at low temperature and that the Q130E mutation imparts considerable changes to PSII electron transfer kinetics, essentially protecting the complex via increased non-radiative charge Photosynthesis in general is a key biological process on Earth and Photo system II (PSII) is an important component of this process. PSII is the only enzyme capable of oxidizing water and is largely responsible for the primordial build-up and present maintenance of the oxygen in the atmosphere. This thesis endeavoured to understand the link between structure and function in PSII with special focus on primary photochemistry, repair/photodamage and spectral characteristics. The deletion of the PsbU subunit ofPSII in cyanobacteria caused a decoupling of the Phycobilisomes (PBS) from PSII, likely as a result of increased rates of PSII photodamage with the PBS decoupling acting as a measure to protect PSII from further damage. Isolated fractions of spinach thylakoid membranes were utilized to characterize the heterogeneity present in the various compartments of the thylakoid membrane. It was found that the pooled PSIILHCII pigment populations were connected in the grana stack and there was also a progressive decrease in the reaction rates of primary photochemistry and antennae size of PSII as the sample origin moved from grana to stroma. The results were consistent with PSII complexes becoming damaged in the grana and being sent to the stroma for repair. The dramatic quenching of variable fluorescence and overall fluorescent yield of PSII in desiccated lichens was also studied in order to investigate the mechanism by which the quenching operated. It was determined that the source of the quenching was a novel long wavelength emitting external quencher. Point mutations to amino acids acting as ligands to chromophores of interest in PSII were utilized in cyanobacteria to determine the role of specific chromophores in energy transfer and primary photochemistry. These results indicated that the Hl14 ligated chlorophyll acts as the 'trap' chlorophyll in CP47 at low temperature and that the Q130E mutation imparts considerable changes to PSII electron transfer kinetics, essentially protecting the complex via increased non-radiative charge.