Fernando Manuel Henriques
Universidade Nova de Lisboa, Ciências da Vida, Faculty Member
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Research Interests: Chemistry, Analytical Chemistry, Inorganic Chemistry, Environmental Remediation, Phytoremediation, and 10 moreEnvironmental Chemistry, Legislation, Plant species, Radioanalytical and Nuclear chemistry, Vascular Plants, Iberian Pyrite Belt, Soil Water, Agrostis castellana, Toxic elements, and agrostis
ABSTRACT Rice (Oryza sativa L.) plants were grown over a 30-day period in nutrient solution containing concentrations of copper varying from 0.002 to 6.25 mg/L. Shoot contents of copper, net photosynthesis, intercellular C02, stomatal... more
ABSTRACT Rice (Oryza sativa L.) plants were grown over a 30-day period in nutrient solution containing concentrations of copper varying from 0.002 to 6.25 mg/L. Shoot contents of copper, net photosynthesis, intercellular C02, stomatal conductance and photosynthetic capacity were measured. Copper concentration increased in the shoot with increasing levels of the metal in the solution, decreasing net photosynthesis and photosynthetic capacity above the 0.01 mg/L Cu treatment. Comparison of the effects of increasing copper concentrations on stomatal conductance to water and to intercellular CO2 concentrations in relation to net photosynthesis showed no significant differences. Chlorophyll a fluorescence measurements, partly supported by measurements of ATP synthetase activity and electron microscopy studies of thylakoids, suggested a primary site of copper inhibition on the antenna chlorophyll a molecules of PSII. Our data suggest that this copper inhibition can be attributed to thermal damage of photosynthetic membranes, which in turn limits the yield of ATP and NADPH required for the reductive pentosephosphate cycle.
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ABSTRACT This review on chlorophyll a fluorescence starts with an overview of the primary photochemistry occurring at PSII and a characterization of the so-called "open" and "closed" states of its... more
ABSTRACT This review on chlorophyll a fluorescence starts with an overview of the primary photochemistry occurring at PSII and a characterization of the so-called "open" and "closed" states of its reaction centers. This provides the theoretical background for understanding the origin of PSII-emitted fluorescence and how its yield varies with the fraction of open reaction centers. The review proceeds to discuss the changes in fluorescence emission following illumination of a dark-adapted leaf and to define the PSII intrinsic quantum yield of photochemistry, which in turn provides an indication of PSII capacity. In light-adapted leaves, it is discussed how the use of modulated fluorometers and the double lighting technique allow an evaluation of photochemical and non-photochemical quenching, two parameters that give useful information about the plant's photosynthetic performance under field conditions. Finally, it is described how the PSII operational efficiency can be used to calculate the photosynthetic electron transport rate and the conditions under which this is linearly related to the CO2 assimilation rate. Some requirements for a valid application of the technique as well as some limitations in interpreting its results are discussed.
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... entre pessimistas, que calculam que apenas 5 -10% da floresta tropical original sobreviverá em 2050 (Laurance, 1999; Dirzo, 2003; Millennium Ecos. ... Internacional de Primatologia elaborou uma lista das 25 espécies de primatas em... more
... entre pessimistas, que calculam que apenas 5 -10% da floresta tropical original sobreviverá em 2050 (Laurance, 1999; Dirzo, 2003; Millennium Ecos. ... Internacional de Primatologia elaborou uma lista das 25 espécies de primatas em maior risco de extinção -11 na Ásia, 7 na ...
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ABSTRACT Typha latifolia L. is one of the major plant species occurring in a pyrites mine tailing‐derived, waterlogged soil at Lousal, south of Portugal. Levels of Fe, Mn, Zn, Cu and Pb were measured in both below‐ and above‐ground... more
ABSTRACT Typha latifolia L. is one of the major plant species occurring in a pyrites mine tailing‐derived, waterlogged soil at Lousal, south of Portugal. Levels of Fe, Mn, Zn, Cu and Pb were measured in both below‐ and above‐ground tissues of Typha latifolia, as well as in the substrate supporting the plants. Metal levels in the soil, excluding Mn, were found to be substantially higher than in control soils, showing relative enrichment of Cu and Pb of the order of 20–70 times and 10–20 times, respectively. Compared to Typha latifolia controls collected from a nearby creek, upstream from the pyrites mine zone, the plants growing in the contaminated soil showed higher metal levels in their organs, with exception of Mn. Similarly to previous findings from other authors, we observed that the roots of Typha latifolia presented iron contents that were often much higher than those measured in the soil, which is probably due to the formation of a ferric hydroxide plaque at the root surface. Rhizome stripping showed that a large fraction of the Fe measured in this organ was associated with its external layer, supporting the view that varying, but significant amounts of this metal were adherent to the subterranean plant organs. Typha latifolia plants showed great capacity to accumulate manganese against a concentration gradient and to selectively prevent potentially toxic metal levels from reaching the shoot.
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Research Interests: Plant Biology, Protein Structure and Function, Plant Physiology, Nitrogen Fixation, Copper, and 13 moreHeavy Metal Pollution, Heavy Metal, Metallothionein, Electron Transport, Enzyme, Protein Metabolism, Botanical, Fatty Acid, Membrane Integrity, Growth Inhibition, The Botanical, Vegetative Growth, and Environmental Problem
ABSTRACT This review on chlorophyll a fluorescence starts with an overview of the primary photochemistry occurring at PSII and a characterization of the so-called "open" and "closed" states of its... more
ABSTRACT This review on chlorophyll a fluorescence starts with an overview of the primary photochemistry occurring at PSII and a characterization of the so-called "open" and "closed" states of its reaction centers. This provides the theoretical background for understanding the origin of PSII-emitted fluorescence and how its yield varies with the fraction of open reaction centers. The review proceeds to discuss the changes in fluorescence emission following illumination of a dark-adapted leaf and to define the PSII intrinsic quantum yield of photochemistry, which in turn provides an indication of PSII capacity. In light-adapted leaves, it is discussed how the use of modulated fluorometers and the double lighting technique allow an evaluation of photochemical and non-photochemical quenching, two parameters that give useful information about the plant's photosynthetic performance under field conditions. Finally, it is described how the PSII operational efficiency can be used to calculate the photosynthetic electron transport rate and the conditions under which this is linearly related to the CO2 assimilation rate. Some requirements for a valid application of the technique as well as some limitations in interpreting its results are discussed.
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ABSTRACT Rice (Oryza sativa L.) plants were grown for 1 month in nutrient solutions containing Cu concentrations ranging from 0.002 to 6.25 mg/L-and then subjected to kinetic studies of metal absorption and to biomass yield measurements.... more
ABSTRACT Rice (Oryza sativa L.) plants were grown for 1 month in nutrient solutions containing Cu concentrations ranging from 0.002 to 6.25 mg/L-and then subjected to kinetic studies of metal absorption and to biomass yield measurements. A biphasic kinetic pattern was found for Cu uptake rates, with a transition phase occurring at metal concentrations between 0.05 and 0.25 mg/L. From the apparent Vmax and Km values, it is proposed that Cu is absorbed by an active mechanism up to concentrations of 0.05 mg/L in the nutrient solution, with a passive absorption mechanism progressively taking over for increasing concentrations of the metal. The Cu uptake pattern is discussed in relation to biomass yields, which reach a maximum value in the 0.25 mg/L Cu treatment at the end of the 30-day experimental period. Data on translocation rates of Cu to the shoot are also presented.
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... AND DISTRIBUTION IN RUSH (JUNCUS CONGLOMERATUS L.) PLANTS GROWING IN PYRITES MINE TAILINGS AT LOUSAL, PORTUGAL* FERNANDO S. HENRIQUES ... Menon and Ghuman (1985) also found higher Mn and Zn levels in dead tissues than in living plants... more
... AND DISTRIBUTION IN RUSH (JUNCUS CONGLOMERATUS L.) PLANTS GROWING IN PYRITES MINE TAILINGS AT LOUSAL, PORTUGAL* FERNANDO S. HENRIQUES ... Menon and Ghuman (1985) also found higher Mn and Zn levels in dead tissues than in living plants of ...
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Recent claims of metal contamination in the lower reaches of the Sado River, in the Alcácer do Sal region, Portugal, a major rice-producing area were investigated by carrying out metal surveys in the area. The elements Fe, Mn, Zn, Cu and... more
Recent claims of metal contamination in the lower reaches of the Sado River, in the Alcácer do Sal region, Portugal, a major rice-producing area were investigated by carrying out metal surveys in the area. The elements Fe, Mn, Zn, Cu and Pb were measured in the soil and in rice plant parts--roots, shoots and grain--as well as in some weeds growing in the Sado banks, near the paddy fields. Results showed that the metal contents of paddy soils were similar to background concentrations, with the exception of Zn and Cu, which were above those concentrations and reached their highest levels at Vale de Guizo, the monitored station located furthest upstream in the Sado River. At some sites, plant roots accumulated relatively large amounts of Fe, Mn, Zn and Cu, but the shoot levels of these metals were within the normal range for rice plants. It is possible that varying, but significant, amounts of Fe associated with the roots were in the form of ferric hydroxide plaque covering their surfaces. Copper levels in the shoots of rice were below the normal contents cited for this plant in the literature. Metal levels of river sediments collected near Vale de Guizo seem to corroborate the possibility of some metal contamination in the Sado River, most probably derived from pyrites mining activity in the upper zone of the Sado basin.
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ABSTRACT The photosynthetic process of rice (Oryza sativa L.) plants grown over a 30-day period in a nutrient solution containing concentrations of copper ranging from 0.002 to 6.25 mg/L was investigated. The PSII-dependent H2O to DCIP... more
ABSTRACT The photosynthetic process of rice (Oryza sativa L.) plants grown over a 30-day period in a nutrient solution containing concentrations of copper ranging from 0.002 to 6.25 mg/L was investigated. The PSII-dependent H2O to DCIP electron transport showed its maximum in the 0.05 mg/L Cu treatment and decreased thereafter with increasing copper levels in the solution; however, when DPC was used, the electron transfer rate to DCIP was less inactivated. The DCIP to MV, as well as the over-all H2O to MV electron transfer, showed a continuous rate decrease from the 0.01 to the 6.25 mg/L Cu treatments. The experimental data indicate that copper inhibits the photosynthetic electron transport mainly before the DPC donation site in the PSII. The activities of Rubisco were also determined and showed a progressive decrease with increasing copper levels in the solution medium. We conclude that although excess copper affects the photosynthetic process in multiple ways, the prevailing effect is that on the activity of Rubisco, which in turn limits the over-all photosynthetic activity.
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... This work was also an attempt to better our understanding about the variations triggered by excess Cu on root growth as well as metal net uptake and translocation rate. Possible effects of excess Cu on the rice growth in the Alcacer... more
... This work was also an attempt to better our understanding about the variations triggered by excess Cu on root growth as well as metal net uptake and translocation rate. Possible effects of excess Cu on the rice growth in the Alcacer do Sal fields were also evaluated. ...
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Typha latifolia L. is one of the major plant species occurring in a pyrites mine tailing‐derived, waterlogged soil at Lousal, south of Portugal. Levels of Fe, Mn, Zn, Cu and Pb were measured in both below‐and above‐ground tissues of Typha... more
Typha latifolia L. is one of the major plant species occurring in a pyrites mine tailing‐derived, waterlogged soil at Lousal, south of Portugal. Levels of Fe, Mn, Zn, Cu and Pb were measured in both below‐and above‐ground tissues of Typha latifolia, as well as in the ...
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Thin sections of malva (Malva sp.) leaves collected in the field and showing mottle and vein-clearing symptoms were examined by electron microscopy. Cytoplasmic inclusions typical of potyvirus and consisting of pinwheels, laminated... more
Thin sections of malva (Malva sp.) leaves collected in the field and showing mottle and vein-clearing symptoms were examined by electron microscopy. Cytoplasmic inclusions typical of potyvirus and consisting of pinwheels, laminated aggregates, and scrolls were readily observed. In addition, rhabdoviruslike particles were also seen in the perinuclear space of phloem parenchyma cells and within membranous sacs scattered throughout the cytoplasm of other vascular bundle cells. Occasionally rhabdoparticles could be found embedded in an amorphous electron-dense body located within the cell vacuole. The rhabdovirus particles, approximately 75 × 300 nm, were bound by a membrane with outer projections and had an inner core displaying cross striations. The cytoplasm of infected mesophyll cells had chloroplasts containing large amorphous inclusion bodies and had extensive membranous tubules that were frequently associated with the potyvirus inclusions. These ultrastructural aspects, the size ...
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... Dixit, V., Padey, V., Shyam, R.: Chromium ions inactivate electron transport and enhance superoxide generation in vivo in pea (Pisum sativum L., cv. ... Yano, J., Kern, J., Sauer, K., Latimer, M., Pushkar, J., Biesiadka, J., Loll, B.,... more
... Dixit, V., Padey, V., Shyam, R.: Chromium ions inactivate electron transport and enhance superoxide generation in vivo in pea (Pisum sativum L., cv. ... Yano, J., Kern, J., Sauer, K., Latimer, M., Pushkar, J., Biesiadka, J., Loll, B., Saenger, W., Messinger, J., Zouni, A., Yachandra, V ...
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ABSTRACT Rice (Oryza sativa L.) plants were grown over a 30-d period in nutrient solution containing concentrations of Cu varying from 0.002 to 6.25 g m-3, and then oxygen toxicity was investigated in the chloroplasts. The Cu... more
ABSTRACT Rice (Oryza sativa L.) plants were grown over a 30-d period in nutrient solution containing concentrations of Cu varying from 0.002 to 6.25 g m-3, and then oxygen toxicity was investigated in the chloroplasts. The Cu concentration in the shoots increased with increasing levels of this metal in the nutrient solution, whereas the Fe concentration decreased after the 0.05 g m-3 Cu treatment and the Zn concentration did not show any clear trend. Catalase, glutathione reductase and Cu,Zn-superoxide dismutase activities decreased with increasing Cu levels. On a fresh mass basis, ethylene production decreased after the 0.05 g m-3 Cu treatment, whereas, on a chlorophyll (ChI) basis, it increased until the 1.25 g m-3 Cu treatment. The chloroplast lipid peroxidation increased (on a Chl and lipid basis) between the 0.01 and the 1.25 g m-3 Cu treatment. On a fresh mass basis the concentration of chloroplastic digalactosyldiacylglycerol, monogalactosyldiacylglycerol, phospha-tidylcholine, phosphatidylglycerol and phosphatidylinositol decreased, whereas, on a ChI basis, the concentration of the fiTst two lipids sharply decreased after the 0.01 g m-3 Cu treatment. Additionally, only a slight decrease was found in the concentration of phosphatidylglycerol with increasing Cu concentrations. Measurements of the linolenate hydroperoxide concentration in these acyl lipids showed an increase after the 0.01 g m-3 Cu treatment for the first two lipids as well as an increase with increasing Cu levels for phosphatidylglycerol. r- .
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Changes in pigment content, photosynthetic CO2 assimilation rate, photosystem II photochemical efficiency and lipid peroxidation of pecan [Carya illinoinensis (Wangenh.) C. Koch, cv. Kiowa] leaves induced by Mn deficiency were examined.... more
Changes in pigment content, photosynthetic CO2 assimilation rate, photosystem II photochemical efficiency and lipid peroxidation of pecan [Carya illinoinensis (Wangenh.) C. Koch, cv. Kiowa] leaves induced by Mn deficiency were examined. Mn limitation was found to cause extensive declines in total chlorophyll and carotenoid contents in leaves, but it only slightly affected the chl a:b and chl:car ratios. Photosynthetic CO2 assimilation rates per unit leaf area decreased with the decreasing chlorophyll content in such a manner that the photosynthetic rates of Mn-deficient leaves were identical to those of controls when expressed on a chlorophyll weight basis. Chlorophyll fluorescence induction measurements showed that the ratio of variable to maximum (Fv:Fm) fluorescence underwent only small decreases with increasing manganese deficiency, indicating that the intrinsic quantum efficiency of the PSII units remaining in Mn-deprived leaves was not significantly decreased. Further, the net...
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Arsenic is a type 1 carcinogen and its toxicity is critically dependent on chemical speciation. However, after decades of research, the biogenesis of at least fifty naturally occurring arsenic species is still not well understood. Here,... more
Arsenic is a type 1 carcinogen and its toxicity is critically dependent on chemical speciation. However, after decades of research, the biogenesis of at least fifty naturally occurring arsenic species is still not well understood.
Here, based on experimental work, it is proposed a set of pathways for the formation of multiple arsenic species that might help to clarify the present situation.
These are focused on the thiol protein arsenic bond and on its interaction with reactive metabolites. In fact, arsenic bound to glutathione interacting with sulfur adenosyl methionine (SAM), MethylCB12 and AdoCB12, forms a number of complexes that might be key intermediates in arsenic biochemistry. These include dimethylarsino glutathione (DMAG) m/z 412 [M+H] +, synthesized non-enzymatically from glutathione and cacodylate. Trimethylarsonio glutathione (TMAG) m/z 426 [M] + synthesized from DMA, GSH and SAM, apparently by a classical Challenger methylcarbonium attack. Tetramethyl arsonium ion m/z 135 [M] + is formed in a third step, apparently by carbanion methylation. The presence of trimethylarsine oxide (TMAO) m/z 137 [M+H] + is attributed to the hydrolysis of TMAG or TMA, or to carbanion methylation of dimethylarsinoyl glutathione (m/z 428 [M] +) formed from cacodylate and GSH. Cantoni type attacks of DMAG on SAM were unsuccessful, eventually due to competition of the trivalent S+ atom of SAM for the AsIII atom attack. The presence of dimethylarsonio diglutathione (DMADG m/z 717 [M] +), is suggested to result from a GS- attack on dimethylarsenoyl glutathione (m/z 428 [M+H] +). The presence of dimethylarsenoyladenosine (m/z 372 [M+H] +), trimethylarsenosugar adenine (m/z 370 [M] +), and dimethylthioarsenosugar adenine (m/z 388 [M+H] +), is explained by the synthesis of the pecursor dimethylarsonioadenosine glutathione DMAAG (m/z 661 [M] +), a likely source of oxo-and trimethylated arsenosugars, as well as of thio-arsenosugars by the cleavage of its SC bond. The results gathered suggest that cell vacuoles might play a major role in arsenic metabolism, and that the dominance of oxo-As sugars, in algae extracts, may be supported by a mechanism of synthesis independent of DMAAG (m/z 661).
They also offer an explanation for the reason why arsenobetaine, and tetramethylarsonium are loosely bound to biotic tissues. Four arsenic species new to science, to the best of our knowledge, and a number of known arsenic compounds were synthesized in this work, identified by HPLC-ESI-MSn and FTICR-ESI-MS, andsuggestions regarding their mechanisms of synthesis were advanced. These resultsprovide a framework for arsenic biochemistry which may explain the origin of a
significant part of arsenic known metabolites.
Here, based on experimental work, it is proposed a set of pathways for the formation of multiple arsenic species that might help to clarify the present situation.
These are focused on the thiol protein arsenic bond and on its interaction with reactive metabolites. In fact, arsenic bound to glutathione interacting with sulfur adenosyl methionine (SAM), MethylCB12 and AdoCB12, forms a number of complexes that might be key intermediates in arsenic biochemistry. These include dimethylarsino glutathione (DMAG) m/z 412 [M+H] +, synthesized non-enzymatically from glutathione and cacodylate. Trimethylarsonio glutathione (TMAG) m/z 426 [M] + synthesized from DMA, GSH and SAM, apparently by a classical Challenger methylcarbonium attack. Tetramethyl arsonium ion m/z 135 [M] + is formed in a third step, apparently by carbanion methylation. The presence of trimethylarsine oxide (TMAO) m/z 137 [M+H] + is attributed to the hydrolysis of TMAG or TMA, or to carbanion methylation of dimethylarsinoyl glutathione (m/z 428 [M] +) formed from cacodylate and GSH. Cantoni type attacks of DMAG on SAM were unsuccessful, eventually due to competition of the trivalent S+ atom of SAM for the AsIII atom attack. The presence of dimethylarsonio diglutathione (DMADG m/z 717 [M] +), is suggested to result from a GS- attack on dimethylarsenoyl glutathione (m/z 428 [M+H] +). The presence of dimethylarsenoyladenosine (m/z 372 [M+H] +), trimethylarsenosugar adenine (m/z 370 [M] +), and dimethylthioarsenosugar adenine (m/z 388 [M+H] +), is explained by the synthesis of the pecursor dimethylarsonioadenosine glutathione DMAAG (m/z 661 [M] +), a likely source of oxo-and trimethylated arsenosugars, as well as of thio-arsenosugars by the cleavage of its SC bond. The results gathered suggest that cell vacuoles might play a major role in arsenic metabolism, and that the dominance of oxo-As sugars, in algae extracts, may be supported by a mechanism of synthesis independent of DMAAG (m/z 661).
They also offer an explanation for the reason why arsenobetaine, and tetramethylarsonium are loosely bound to biotic tissues. Four arsenic species new to science, to the best of our knowledge, and a number of known arsenic compounds were synthesized in this work, identified by HPLC-ESI-MSn and FTICR-ESI-MS, andsuggestions regarding their mechanisms of synthesis were advanced. These resultsprovide a framework for arsenic biochemistry which may explain the origin of a
significant part of arsenic known metabolites.
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Page 1. Page Six Fernando Henriques domination through racialism ... Alexander Knox, Gobineau and Houston Chamberlain are 19th Century figures. The endeavour is to pro-vide a rationale of exploitation in order to remove the guilt which is... more
Page 1. Page Six Fernando Henriques domination through racialism ... Alexander Knox, Gobineau and Houston Chamberlain are 19th Century figures. The endeavour is to pro-vide a rationale of exploitation in order to remove the guilt which is inherent in such a situation. ...
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Research Interests: Water, Wetlands, Health, Prevention, Sampling, and 9 morePopulation, Surveys, Estuaries, Data Bases, Sediments, Translocation, Industries, Effluents, and Hazards
ABSTRACT
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The protein-Arsenic bond interacting with reactive metabolites such as Sulfur-adenosyl-methionine (SAM) and Methyl-cobalamin (Met-CB12), form intermediate complexes that might have a key role in the Arsenic chemistry of living systems.... more
The protein-Arsenic bond interacting with reactive metabolites such as Sulfur-adenosyl-methionine (SAM) and Methyl-cobalamin (Met-CB12), form intermediate complexes that might have a key role in the Arsenic chemistry of living systems. Particularly it seems reasonable to assume that the DMAsIIIGS complex (DMAG) (m/z 412 [M+H]+), formed from Cacodylate (DMA), Glutathione (GSH) and SAM, may have such a role. In this work it has been achieved the non-enzymatic synthesis of Trimethylarsonio glutathione, (GS-As+(CH3)3,(m/z 426), from DMAG, obtained in vitro, and SAM, apparently through the classical Challenger methylcarbonium attack. Full scan and MSn spectra as well accurate mass measurements obtained by electrospray ionization mass spectrometry strongly suggest that such complex (GS-As+(CH3)3)(m/z 426), was formed in the experiment. This intermediate, was apparently further methylated by the complex GSH-methylCB12, leading to the synthesis of Tetramethylarsonium ion As+(CH3)4 (m/z 135)...
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A comparative study of polypeptide composition and freeze-fracture morphology of chloroplast membranes isolated from different, but photosynthetically active, regions of a romaine lettuce shoot is presented. Chloroplasts prepared from... more
A comparative study of polypeptide composition and freeze-fracture morphology of chloroplast membranes isolated from different, but photosynthetically active, regions of a romaine lettuce shoot is presented. Chloroplasts prepared from outer dark-green leaves possess a fully developed light-harvesting chlorophyll-protein complex, have low chlorophyll a:b ratios and display fracture faces similar to those found in other higher plant chloroplast membranes; chloroplasts from leaves more to the interior of the shoot, have a much lower content of chlorophyll, show high chlorophyll a:b ratios, are depleted in components of the light-harvesting chlorophyll-protein complex, and exhibit extensive modifications of their fracture faces. We have also re-examined the freeze-fracture morphology of chloroplast membranes from a barley b-deficient mutant that lacks the light-harvesting chlorophyll-protein complex. A tentative interpretation of our findings suggests correlating the assembly of the light-harvesting chlorophyll-protein complex into the chloroplast membranes with the appearance of large freeze-fracture B face particles in the stacked interior-membrane region, and differentiation of typical fracture faces.