Chlorophyll fluorescence and internal patterns of 14CO2 fixation were measured in sun and shade l... more Chlorophyll fluorescence and internal patterns of 14CO2 fixation were measured in sun and shade leaves of spinach after treatment with various light intensities. When sun leaves were irradiated with 2000μmol m−2 s−1 for 2h, FV/FM decreased by about 15%, but 14CO2 fixation was unaffected, whereas shade leaves exhibited a 21% decrease in Fv/FM and a 25% decrease in 14CO2 fixation. Irradiation of sun and shade leaves with 4000μmol m−1 for 4 h decreased FV/FM by 30% in sun leaves and 40% in shade leaves, while total 14CO2 fixation decreased by 41% in sun leaves and 55% in shade leaves. After light treatment, gradients of CO2 fixation across leaves were determined by measuring 14CO2 fixed in paradermal leaf sections after a 10s pulse of 14CO2. Gradients of 14CO2 fixation in control sun and shade leaves were identified when expressed on a relative basis and normalized for leaf depth. Treatment of leaves with 2000 μmol PAR m−2 s−1 for 2h did not after patterns of carbon fixation across sun leaves, but slightly altered the pattern in shade leaves. In contrast, treatment of sun and shade leaves with 4000μmol m−2 s−1 for 4h decreased carbon fixation more in the palisade mesophyll cells than in the spongy mesophyll cells of sun and shade leaves, and fixation in medial tissue of shade leaves was dramatically decreased compared to the adaxial and abaxial tissue. The interaction between leaf anatomy and biochemical parameters involved in tolerance to photoinhibition in spinach is discussed.
14Carbon methyl-β-D-glucopyranoside (14C-MeG) was applied to roots and shoots of Beta vulgaris L.... more 14Carbon methyl-β-D-glucopyranoside (14C-MeG) was applied to roots and shoots of Beta vulgaris L. and the label was tracked as it was transported and assimilated, primarily as a plant nutrient. Foliar application resulted in 6.7% of the 14C-MeG absorbed within 15 min of the solution drying into leaves. Roots in liquid medium with dissolved 14C-MeG absorbed approximately 97% of the 14C-label in 22 h. Whether fed in the light or dark, 40% of the 14C-MeG that was applied appeared in the cellulose fraction, incorporated completely intact. Rapid incorporation of 14C-MeG into the insoluble fraction with few 14C-labeled metabolites found in the soluble fraction were observed. In contrast to roots, a higher percentage of 14C-MeG was incorporated into starch and lipids of shoots.
The localization of the key photoreductive and oxidative processes and some stress-protective rea... more The localization of the key photoreductive and oxidative processes and some stress-protective reactions within leaves of mesophytic C3 plants were investigated. The role of light in determining the profile of Rubisco, glutamate oxaloacetate transaminase, catalase, fumarase, and cytochrome-c-oxidase across spinach leaves was examined by exposing leaves to illumination on either the adaxial or abaxial leaf surfaces. Oxygen evolution in fresh paradermal leaf sections and CO2 gas exchange in whole leaves under adaxial or abaxial illumination was also examined. The results showed that the palisade mesophyll is responsible for the midday depression of photosynthesis in spinach leaves. The photosynthetic apparatus was more sensitive to the light environment than the respiratory apparatus. Additionally, examination of the paradermal leaf sections by optical microscopy allowed us to describe two new types of parenchyma in spinach—pirum mesophyll and pillow spongy mesophyll. A hypothesis that oxaloacetate may protect the upper leaf tissue from the destructive influence of active oxygen is presented. The application of mathematical modeling shows that the pattern of enzymatic distribution across leaves abides by the principle of maximal ecological utility. Light regulation of carbon metabolism across leaves is discussed.
A simple method using the O2 electrode that allows examination of the response of respiration and... more A simple method using the O2 electrode that allows examination of the response of respiration and photosynthesis in leaf slices or algae to anoxia and high light under different temperatures useful for the examination of the interactions among photosynthesis, photorespiration, and respiration is described. The method provides a quantifiable assessment of stress tolerance that also permits us to examine fundamental biochemically and genetically related responses involved in stress tolerance and the cooperation among organelles. Additionally, we demonstrated a role for compounds, such as $ {\text{NO}}^{{\text{ - }}}_{{\text{3}}} $ and oxaloacetate, as protective agents against photoinhibition, and we examined the role of dark adaptation in the activation of photosynthesis and $ {\text{NO}}^{{\text{ - }}}_{{\text{3}}} $ -dependent O2 oxygen evolution. A physiological and ecological role of a dark period (night) in stress tolerance is presented. Utilizing the method to follow changes in such metabolic activities as protein synthesis, protein conformation states, enzymes activity, carbon metabolism, and gene expression at different points during the treatments will be educational.
The effect of Fe chlorosis on the mineral composition of field grown peach tree leaves was studie... more The effect of Fe chlorosis on the mineral composition of field grown peach tree leaves was studied in two different areas. No significant differences in total Fe content were found, whereas 2,2’ bipyridyl extractable Fe, K and the K/Ca ratio were significantly affected in both experiments. Phosphorus and the P/Fe ratio were significantly affected only in one experiment.
The chlorophyll-protein and polypeptide composition of manganese deficient and control sugar beet... more The chlorophyll-protein and polypeptide composition of manganese deficient and control sugar beet thylakoids was examined using three different detergent-electrophoresis systems. On a per chlorophyll basis, manganese deficiency reduced the amounts of CPa complex (separated by sodium dodecylsulfate (SDS)-polyacrylamide gel electrophoresis), and CP 47 and CP 43 complexes (separated by octylglucoside/SDS-polyacrylamide gel electrophoresis) without decreasing the amounts of light harvesting complexes. Lithium dodecylsulfate/Triton X-100 polyacrylamide gel electrophoresis showed that manganese deficiency decreased several thylakoid polypeptides, including a chlorophyll b containing 30 kilodalton chlorophyll-protein complex, but did not decrease the amounts of 28 and 29 kilodalton light-harvesting chlorophyll b-containing polypeptides.
Chlorophyll fluorescence and internal patterns of 14CO2 fixation were measured in sun and shade l... more Chlorophyll fluorescence and internal patterns of 14CO2 fixation were measured in sun and shade leaves of spinach after treatment with various light intensities. When sun leaves were irradiated with 2000μmol m−2 s−1 for 2h, FV/FM decreased by about 15%, but 14CO2 fixation was unaffected, whereas shade leaves exhibited a 21% decrease in Fv/FM and a 25% decrease in 14CO2 fixation. Irradiation of sun and shade leaves with 4000μmol m−1 for 4 h decreased FV/FM by 30% in sun leaves and 40% in shade leaves, while total 14CO2 fixation decreased by 41% in sun leaves and 55% in shade leaves. After light treatment, gradients of CO2 fixation across leaves were determined by measuring 14CO2 fixed in paradermal leaf sections after a 10s pulse of 14CO2. Gradients of 14CO2 fixation in control sun and shade leaves were identified when expressed on a relative basis and normalized for leaf depth. Treatment of leaves with 2000 μmol PAR m−2 s−1 for 2h did not after patterns of carbon fixation across sun leaves, but slightly altered the pattern in shade leaves. In contrast, treatment of sun and shade leaves with 4000μmol m−2 s−1 for 4h decreased carbon fixation more in the palisade mesophyll cells than in the spongy mesophyll cells of sun and shade leaves, and fixation in medial tissue of shade leaves was dramatically decreased compared to the adaxial and abaxial tissue. The interaction between leaf anatomy and biochemical parameters involved in tolerance to photoinhibition in spinach is discussed.
14Carbon methyl-β-D-glucopyranoside (14C-MeG) was applied to roots and shoots of Beta vulgaris L.... more 14Carbon methyl-β-D-glucopyranoside (14C-MeG) was applied to roots and shoots of Beta vulgaris L. and the label was tracked as it was transported and assimilated, primarily as a plant nutrient. Foliar application resulted in 6.7% of the 14C-MeG absorbed within 15 min of the solution drying into leaves. Roots in liquid medium with dissolved 14C-MeG absorbed approximately 97% of the 14C-label in 22 h. Whether fed in the light or dark, 40% of the 14C-MeG that was applied appeared in the cellulose fraction, incorporated completely intact. Rapid incorporation of 14C-MeG into the insoluble fraction with few 14C-labeled metabolites found in the soluble fraction were observed. In contrast to roots, a higher percentage of 14C-MeG was incorporated into starch and lipids of shoots.
The localization of the key photoreductive and oxidative processes and some stress-protective rea... more The localization of the key photoreductive and oxidative processes and some stress-protective reactions within leaves of mesophytic C3 plants were investigated. The role of light in determining the profile of Rubisco, glutamate oxaloacetate transaminase, catalase, fumarase, and cytochrome-c-oxidase across spinach leaves was examined by exposing leaves to illumination on either the adaxial or abaxial leaf surfaces. Oxygen evolution in fresh paradermal leaf sections and CO2 gas exchange in whole leaves under adaxial or abaxial illumination was also examined. The results showed that the palisade mesophyll is responsible for the midday depression of photosynthesis in spinach leaves. The photosynthetic apparatus was more sensitive to the light environment than the respiratory apparatus. Additionally, examination of the paradermal leaf sections by optical microscopy allowed us to describe two new types of parenchyma in spinach—pirum mesophyll and pillow spongy mesophyll. A hypothesis that oxaloacetate may protect the upper leaf tissue from the destructive influence of active oxygen is presented. The application of mathematical modeling shows that the pattern of enzymatic distribution across leaves abides by the principle of maximal ecological utility. Light regulation of carbon metabolism across leaves is discussed.
A simple method using the O2 electrode that allows examination of the response of respiration and... more A simple method using the O2 electrode that allows examination of the response of respiration and photosynthesis in leaf slices or algae to anoxia and high light under different temperatures useful for the examination of the interactions among photosynthesis, photorespiration, and respiration is described. The method provides a quantifiable assessment of stress tolerance that also permits us to examine fundamental biochemically and genetically related responses involved in stress tolerance and the cooperation among organelles. Additionally, we demonstrated a role for compounds, such as $ {\text{NO}}^{{\text{ - }}}_{{\text{3}}} $ and oxaloacetate, as protective agents against photoinhibition, and we examined the role of dark adaptation in the activation of photosynthesis and $ {\text{NO}}^{{\text{ - }}}_{{\text{3}}} $ -dependent O2 oxygen evolution. A physiological and ecological role of a dark period (night) in stress tolerance is presented. Utilizing the method to follow changes in such metabolic activities as protein synthesis, protein conformation states, enzymes activity, carbon metabolism, and gene expression at different points during the treatments will be educational.
The effect of Fe chlorosis on the mineral composition of field grown peach tree leaves was studie... more The effect of Fe chlorosis on the mineral composition of field grown peach tree leaves was studied in two different areas. No significant differences in total Fe content were found, whereas 2,2’ bipyridyl extractable Fe, K and the K/Ca ratio were significantly affected in both experiments. Phosphorus and the P/Fe ratio were significantly affected only in one experiment.
The chlorophyll-protein and polypeptide composition of manganese deficient and control sugar beet... more The chlorophyll-protein and polypeptide composition of manganese deficient and control sugar beet thylakoids was examined using three different detergent-electrophoresis systems. On a per chlorophyll basis, manganese deficiency reduced the amounts of CPa complex (separated by sodium dodecylsulfate (SDS)-polyacrylamide gel electrophoresis), and CP 47 and CP 43 complexes (separated by octylglucoside/SDS-polyacrylamide gel electrophoresis) without decreasing the amounts of light harvesting complexes. Lithium dodecylsulfate/Triton X-100 polyacrylamide gel electrophoresis showed that manganese deficiency decreased several thylakoid polypeptides, including a chlorophyll b containing 30 kilodalton chlorophyll-protein complex, but did not decrease the amounts of 28 and 29 kilodalton light-harvesting chlorophyll b-containing polypeptides.
Uploads
Papers by John Nishio