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Cold Acclimation: A Complex Interaction Of Low Temperature, Light And The Redox State Of Photosystem Ii, Gordon R. Gray
Cold Acclimation: A Complex Interaction Of Low Temperature, Light And The Redox State Of Photosystem Ii, Gordon R. Gray
Digitized Theses
The process of cold acclimation refers to the physiological processes by which cold-tolerant plants such as cereals, when developed at low temperature, acquire freezing tolerance. Photosynthesis provides the energy required for these complex metabolic changes to take place. However, photosynthetic organisms must maintain a balance between energy input as a result of photochemical reactions and energy consumption through intersystem electron transport and the various biochemical reactions of cellular metabolism. Imbalances may be sensed by changes in the redox state of photosystem II (PSII), as this represents the rate-limiting step of photosynthetic electron transport. The redox state of PSII is sensitive …
Photosynthetic Acclimation To Light And Temperature: Excitation Pressure And Redox Sensing, Denis Philip Maxwell
Photosynthetic Acclimation To Light And Temperature: Excitation Pressure And Redox Sensing, Denis Philip Maxwell
Digitized Theses
Photosynthetic acclimation to low temperature has been studied extensively. However, since low temperature causes a preferential decrease in the rates of biochemical as compared to photochemical reactions, some alterations brought about by acclimation to low temperature may be the result of the light-harvesting apparatus absorbing more light energy than can be readily dissipated through photosynthesis. This possibility was investigated by using two species of green algae, Chlorella vulgaris and Dunaliella salina and the techniques of chlorophyll a fluorescence, O{dollar}\sb2{dollar}-evolution, protein electrophoresis and Western blotting, high performance liquid chromatography, RNA blot hybridization, and enzyme and metabolite assays. Compared to algae grown …
Ecological Aspects Of Iron Acquisition In Synechococcus Sp (Cyanophyceae), Steven Wray Wilhelm
Ecological Aspects Of Iron Acquisition In Synechococcus Sp (Cyanophyceae), Steven Wray Wilhelm
Digitized Theses
As primary producers, marine cyanobacteria regulate the biological and biogeochemical cycles of aquatic ecosystems and influence ocean-atmosphere gas exchange. The purposes of this project were to determine if a Synechococcus sp. was capable of utilizing a high-affinity iron transport system during periods of iron-limited growth and if physiological changes due to iron limitation could be identified. Resolution of these factors was achieved by maintaining the cyanobacterium Synechococcus sp. PCC 7002 in continuous culture chemostats over a range of iron availabilities.;Changes in physiology were detected over a range of iron concentrations. Reductions in the levels of photosynthetic pigments were accompanied by …
Biosynthesis And Metabolism Of Dolichol And Polyprenol In The Seeds And Seedlings Of Rye (Secale Cereale L), Robert Thomas Rymerson
Biosynthesis And Metabolism Of Dolichol And Polyprenol In The Seeds And Seedlings Of Rye (Secale Cereale L), Robert Thomas Rymerson
Digitized Theses
The seeds of monocotyledonous plants contain both dolichol, an homologous series of {dollar}\alpha{dollar}-saturated polyisoprenoid alcohols, and polyprenol, and homologous series of {dollar}\alpha{dollar}-unsaturated polyisoprenoid alcohols. Dolichyl phosphate (Dol-P) participates in the N-glycosylation of proteins. The function of polyprenol is unknown. Several possible roles for polyprenol were investigated in rye (Secale cereale L.). Methods for the extraction, separation, analysis, and quantification of polyisoprenoids were developed. Rye embryos contained twice as much polyprenol as dolichol; the ratio of polyprenyl phosphate to dolichyl phosphate was estimated at three to one.;Experiments on the metabolic labelling of polyisoprenoids with ({dollar}\sp3{dollar}H) H{dollar}\sb2{dollar}O, H{dollar}\sb3\lbrack\sp{lcub}32{rcub}{dollar}P) PO{dollar}\sb4{dollar}, or ({dollar}\sp{lcub}14{rcub}{dollar}C) mevalonolactone …
Physiological And Biochemical Significance Of Peanut (Arachis Hypogaea L) Peroxidases In Growth, Xiaohong Zheng
Physiological And Biochemical Significance Of Peanut (Arachis Hypogaea L) Peroxidases In Growth, Xiaohong Zheng
Digitized Theses
The molecular structures of peanut peroxidases from the cell suspension culture medium have been well characterized. The aim of present work is to investigate some of the physiological roles of these peroxidases, namely the functions in growth.;Specific polyclonal antibodies against both anionic and cationic peroxidases were produced by affinity chromatography. Immunological assays showed virtually no cross-reactivity between these antibodies and other compounds. The peroxidases from peanut cell suspension culture medium had {dollar}>{dollar}80% immunological homologies with those from cultured cells and hypocotyls as determined by Ouchterlony gel diffusion, western blot and competitive ELISA. Based on these homologies both the purified …
The Organization Of The Maize Photosystem Ii Light-Harvesting Apparatus Under Normal And Chilling Conditions, Douglas A. Campbell
The Organization Of The Maize Photosystem Ii Light-Harvesting Apparatus Under Normal And Chilling Conditions, Douglas A. Campbell
Digitized Theses
The maize light harvesting system is structurally and functionally perturbed by chilling stress, with alterations in fluorescence parameters and protein processing. The molecular basis for these changes was investigated through biochemical analysis of the photosystem II-associated light-harvesting complexes (LHC II) of maize mesophyll thylakoids.;LHC II complexes from thylakoids were separated into three populations by mildly-denaturing electrophoresis. LHC II-1 contains four polypeptides and is equivalent to the oligomeric LHC IIb complex of Thornber et al. (1988). A less abundant oligomeric band, LHC II-2, contains a subset of the LHC IIb polypeptides, along with the LHC IIa complex (CP 29). The LHC …
Characterisation Of The Photosynthetic Responses Of Spring And Winter Wheat To Growth At Cold-Hardening Temperatures, Vaughan M. Hurry
Characterisation Of The Photosynthetic Responses Of Spring And Winter Wheat To Growth At Cold-Hardening Temperatures, Vaughan M. Hurry
Digitized Theses
In vivo room temperature chlorophyll a fluorescence coupled with CO{dollar}\sb2{dollar} and O{dollar}\sb2{dollar} exchange are measured to determine the effect of cold-hardening on the photosynthetic capacity and the susceptibility to photoinhibition of six cultivars of wheat (Triticum aestivum L.), covering a range of freezing tolerance. The role of the photosystem II (PSII) repair cycle in resistance to, and recovery from, photoinhibition is assessed at both low temperatures (5{dollar}\sp\circ{dollar}C & {dollar}-3\sp\circ{dollar}C) and in the presence of the 70S protein synthesis inhibitor, chloramphenicol. The effect of long-term, repeated photoinhibitory events and sustained reduction in PSII efficiency on net carbon gained is also assessed.;Winter …
Growth Temperature Effects On Photosynthesis And Photoinhibition Of Spinach (Spinacia Oleracea L), Steven Ray Boese
Growth Temperature Effects On Photosynthesis And Photoinhibition Of Spinach (Spinacia Oleracea L), Steven Ray Boese
Digitized Theses
Spinacea oleracea L. cv Savoy was utilized to determine the effects of growth temperature and temperature shifts after leaf expansion on growth, photosynthesis and photoinhibition.;Growth was slowed at 5{dollar}\sp\circ{dollar}C with the second leaves reaching full expansion at 92 days after planting compared to 32 days for 16{dollar}\sp\circ{dollar}C grown plants. Growth at 5{dollar}\sp\circ{dollar}C compared to 16{dollar}\sp\circ{dollar}C resulted in a 2 to 3 fold increases in leaf area, dry weight per area, and leaf thickness of fully expanded leaves. Further, growth at 5{dollar}\sp\circ{dollar}C resulted in an increase from 2 to 3 palisade layers and an increase in the freezing tolerance from {dollar}-2\sp\circ{dollar}C …
Polysome Metabolism In Winter Rye (Secale Cereale Cv Puma), Andre Laroche
Polysome Metabolism In Winter Rye (Secale Cereale Cv Puma), Andre Laroche
Digitized Theses
The effect of growth at low temperature on polysome metabolism in winter rye (Secale cereale cv Puma) has been investigated. A method for isolation of highly polymerized polysomes from mature leaf tissues has been developed. The degree of intactness of isolated polysomes was monitored by two independent but complementary methods: size class distribution on sucrose gradients and in vitro translation. The composition of the optimal polysome isolation buffer for mature rye leaves is similar for leaves grown at low (5{dollar}\sp\circ{dollar}) or high (20{dollar}\sp\circ{dollar}) temperature but different from that reported for young tobacco and pea leaves. The quantity of polysomes (per …
Biosynthesis Of Peroxidase In Peanut Cells In Suspension Culture, Ravindra Nath Chibbar
Biosynthesis Of Peroxidase In Peanut Cells In Suspension Culture, Ravindra Nath Chibbar
Digitized Theses
Peroxidase (E.C.1.11.1.7) has been widely used as a marker of altered growth and development in plants. However, a definitive role of physiological significance has yet to be ascribed. This may be partially due to studies, that have been performed with a peroxidase molecule neither isolated to purity nor characterized from the system of investigation. A cationic peroxidase molecule (molecular weight 40 kD) had been purified to apparent homogenity and characterized from cultured peanut cells. Antibodies were raised against this peroxidase molecule in rabbits and used for monitoring biosynthetic studies on this peroxidase molecule in cultured peanut cells.;The cationic peroxidase constituted …
Study Of Peroxidase Isozymes From Culture Medium Of Peanut Cell Suspension, Om Prakash Srivastava
Study Of Peroxidase Isozymes From Culture Medium Of Peanut Cell Suspension, Om Prakash Srivastava
Digitized Theses
No abstract provided.