Chlorophyll-a content is widely used as an indicator of the quality of freshwater bodies. Quantif... more Chlorophyll-a content is widely used as an indicator of the quality of freshwater bodies. Quantification of chlorophyll-a is a routine procedure in the test laboratories of water works, and in research laboratories. Although attempts have been made to standardise the measurement procedure, there are nonetheless many procedures currently in use. This work is focused on a careful re-examination of the
In early spring 2000, two incidents of bursting dams int he mines Baia Mare and Baia Borsa (Roman... more In early spring 2000, two incidents of bursting dams int he mines Baia Mare and Baia Borsa (Romania) produced peak amounts of cyanide (32 mg 1(-1)) and heavy metals (mostly lead [2.9 mg 1(-1) in April], copper [18 mg 1(-1) in February and 0.86 mg 1(-1) in April] and zinc [0.95 mg 1(-1) in February and 2.9 mg 1(-1) in April] – data at the Romanian-Hungarian border section). A major fish kill and severe damage of benthos populations resulted. The aim of this study was to investigate the impact of the accident on planktonic and periphytic algae. Apart from detailed taxonomic information, diversity, evenness and diatom indices, chlorophyll-a analysis, X-ray fluorescence spectroscopy (TXRF), spectral analysis and SEM were applied. While transient damage of periphyton, especially the sensitive Chladophora glomerata, could be detected in the River Tisza, the phytoplankton did not respond. Flooding may have prevented effects by dilution. The problems related to algae as suitable biota for immediate spill effects are discussed.
The relationship between the structural and functional changes of the photosynthetic apparatus in... more The relationship between the structural and functional changes of the photosynthetic apparatus in the flower bud of Lilium longiflorum during chloroplast–chromoplast transition was examined. Compared with green petals, there was a five‐fold increase of the carotenoid content in yellow petals, whereas the chlorophyll content decreased five‐fold. Absorption and emission fluorescence spectra of chromoplasts indicated that newly synthesized carotenoids were not associated with photosystem II (PSII) photochemistry. The maximum quantum yield in the remaining PSII reaction centers remained constant during the chromoplast formation, whereas the photosynthetic electron transport beyond PSII became inhibited, as indicated by a marked decrease of the O2 evolution capacity, of the photochemical quenching of chlorophyll‐a fluorescence and of the operational quantum yield of photosynthetic electron transport. Deconvoluted fluorescence emission spectra indicated a more rapid degradation of photosystem I (PSI) complexes than of PSII during chromoplast formation. Compared with green petals, the spillover between PSII and PSI decreased by approximately 40% in yellow petals. Our results indicate that during chloroplast–chromoplast transition in the flower bud of L. longiflorum, PSII integrity was preserved longer than the rest of the photosynthetic apparatus.
Pioneering investigations of the chlorophyll biosynthesis have shown that the knowledge of the pr... more Pioneering investigations of the chlorophyll biosynthesis have shown that the knowledge of the primary chemical structure of chlorophylls and their precursors is not nearly enough for understanding of the process of this biosynthesis. This is especially true for the final steps of this process; a large body of data has been accumulated about the complicated spectral phenomena during the phototransformation of protochlorophyllide (PChlide) into chlorophyllide-a (Chlide-a) and the phytilization process (see for review l). This, together with the spectral multiplicity of PChlide must be in connection with the differencies in the molecular interactions of the PChlide molecules and with the changes of these interactions (2,3).
Aggregation and spectroscopic properties of protochlorophyll were investigated in solid films and... more Aggregation and spectroscopic properties of protochlorophyll were investigated in solid films and in Triton X-100 detergent micelles. The protochlorophyll form with absorption maximum at 650 nm appeared in solid films treated with vapour of acetone or water as well in detergent micelles. In addition to this form, several long-wavelength forms were also found especielly in water vapour treated solid films. While the 650 nm and the 676 nm forms had intense CD signals — with positive Cotton effects around 650 nm — another long-wavelength forms were optically inactive. The structural reasons of the differences of spectroscopic properties of protochlorophyll forms are discussed.
ABSTRACT We describe Chloroparva pannonica Somogyi, Felföldi & Vörös gen. et sp. nov., a ... more ABSTRACT We describe Chloroparva pannonica Somogyi, Felföldi & Vörös gen. et sp. nov., a new trebouxiophycean picoplanktonic alga isolated from a turbid, shallow soda pan in Hungary. The cells are spherical to oval, less than 2 mm in diameter, with simple ultrastructure typical to small green algae. Cells divide by autosporulation, forming two daughter cells per autosporangium. Cell wall structure consists of an outer trilaminar layer, an inner microfibrillar layer and an electron transparent layer covering the plasma membrane. The trilaminar layer of the mother cell wall often persists around the autospores. Typical chlorophyte pigments have been found, including chlorophyll a and b and lutein as the dominant carotenoid. The main fatty acid was oleic acid. The phylogenetic position of the new chlorophyte confirms the proposal of a new genus within the Trebouxiophyceae. Based on its 18S rRNA gene sequence, this isolate is distantly related to Nannochloris eucaryotum UTEX 2502, Chlorella minutissima C-1.1.9 and C. minutissima SAG 1.80 (# 97.6% 18S rRNA gene pairwise similarities).
Short-wavelength protochlorophyllide forms and their phototransformation in epicotyl of pea (Pisu... more Short-wavelength protochlorophyllide forms and their phototransformation in epicotyl of pea (Pisum sativum)
Abstract The relationship between the structural and functional changes of the photosynthetic app... more Abstract The relationship between the structural and functional changes of the photosynthetic apparatus in the flower bud of Lilium longiflorum during chloroplast–chromoplast transition was examined. Compared with green petals, there was a five-fold increase of the carotenoid content in yellow petals, whereas the chlorophyll content decreased five-fold. Absorption and emission fluorescence spectra of chromoplasts indicated that newly synthesized carotenoids were not associated with photosystem II (PSII) photochemistry. The maximum quantum yield in the remaining PSII reaction centers remained constant during the chromoplast formation, whereas the photosynthetic electron transport beyond PSII became inhibited, as indicated by a marked decrease of the O2 evolution capacity, of the photochemical quenching of chlorophyll-a fluorescence and of the operational quantum yield of photosynthetic electron transport. Deconvoluted fluorescence emission spectra indicated a more rapid degradation of photosystem I (PSI) complexes than of PSII during chromoplast formation. Compared with green petals, the spillover between PSII and PSI decreased by approximately 40% in yellow petals. Our results indicate that during chloroplast–chromoplast transition in the flower bud of L. longiflorum, PSII integrity was preserved longer than the rest of the photosynthetic apparatus.
Unlike etiolated leaves, epicotyls contain the majority of protochlorophyllide (Pchlide) in monom... more Unlike etiolated leaves, epicotyls contain the majority of protochlorophyllide (Pchlide) in monomer state emitting at 629 and 636 nm at 77 K. The longer wavelength, 644 and 655 nm emitting forms are in small quantities. Flash illumination converts only a small amount of Pchlide. Dark-grown epicotyls can be greened with continuous light of low irradiance only; natural sunlight causes bleaching of the pigments, loos of turgor and wilting. In this work, details of the photosensitivity were studied on intact epicotyls and in their homogenates. Under illumination, an increased amount of water was found in the intracellular spaces in stereo microscopic studies and light activated water-loss of the epicotyls was measured with a potometer. Immediately after preparation, the spectral properties and the photochemical activity of the homogenates were identical to those of intact epicotyls. The bleaching of the samples could be prevented with Na-ascorbate. When homogenates were stored at ? 20 °C for 4 days, the amplitude of the emission band at 636 nm decreased while the 655 nm band increased. Flash illumination caused full photoconversion of this latter form into chlorophyllide emitting at 692 nm. The efficiency of this process was higher than that of intact epicotyls. The light stress reactions, i.e. bleaching and water loss, suggest a free-radical chain reaction process in vivo, which can be stopped with free-radical trap. The spectral changes at ? 20 °C refer to the aggregation of POR subunits, which can be the reason of the increased phototransformation and decreased photosensitivity.
Photoreduction and interconversion processes of different protochlorophyllide complexes were stud... more Photoreduction and interconversion processes of different protochlorophyllide complexes were studied in epicotyl segments of dark-germinated pea (Pisum sativum L.) seed- lings illuminated with low-intensity white or 632.8 nm laser light. Analyses of 77 K fluorescence emission spectra showed the direct phototransformation of the monomer, 636 nm emitting com- plex. The 629 nm emitting complex containing also monomer pigment, regenerated all longer wavelength, flash-photoactive complexes. A dynamic transformation of the protochlorophyllide complexes was also detected during the illumination and/or the subsequent dark-incubation. On the basis of these results, the protochlorophyllide phototransformation schemes can be completed with new pathways.
The photoreduction and photooxidation processes of different protochlorophyll(ide) forms were stu... more The photoreduction and photooxidation processes of different protochlorophyll(ide) forms were studied in the innermost leaves of cabbage (Brassica oleracea var. capitata L.) under monochromatic irradiations. Room-temperature fluorescence emission spectra were measured from the same leaf spots before and after illumination to follow the wavelength dependence of the photochemical reactions. Short-wavelength light of 7 µmol photons m(-2) s(-1) (625-630 nm) provoked mainly bleaching, and longer wavelengths (630-640 nm) caused both bleaching and photoreduction, while above 640 nm resulted in basically photoreduction. When bleached leaves were kept in darkness at room temperature, all protochlorophyll(ide) forms regenerated during 72 h. Oxygen-reduced environment decreased the extent of bleaching suggesting the involvement of reactive oxygen species. These results confirm that the short-wavelength, 628 nm absorbing, and 633 nm emitting protochlorophyll(ide) form in etiolated cabbage leaves sensibilizes photooxidation. However, the 628 nm light at low intensities stimulates the photoreduction of the longer wavelength protochlorophyllide forms. Kinetic measurements showed that photoreduction saturates at a low PFD (photon flux density) compared to bleaching, suggesting that the quantum yield of photoreduction is higher than that of bleaching.
Advances in High Pressure Bioscience and Biotechnology II, 2003
In dark-grown higher plants the chlorophyll biosynthetic pathway stops at protochlorophyllide bec... more In dark-grown higher plants the chlorophyll biosynthetic pathway stops at protochlorophyllide because the enzyme, NADPH-pchlide oxidoreductase (POR), responsible for the transformation of pchlide into chlorophyllide (chlide) requires light for catalysis. As a consequence, the transformation of pchlide into chlorophyllide can be triggered with illumination in dark-grown plants. The newly formed chlorophyllide-enzyme complexes undergo a spectral blue shift. The photoreduction and the blue spectral shift were studied in homogenates prepared from etiolated wheat leaves using fluorescence spectroscopy at pressures up to 400 MPa. The kinetic curves of photoreduction were fitted with the sum of two exponential functions. The activation volumes were calculated from the pressure dependence of the reaction rate constants of the exponential curves at 20 °C and 40 °C. The two activation volumes corresponding to the two processes linked to the photo-transformation of pchlide were 1.8±1.2 mL mol−1 and 2.9±0.5 mL mol−1 at 20 °C, and both activation volumes increased with increasing temperature. The blue shift showed strong pressure dependence below 100 MPa at 20 °C and was almost stopped at pressures higher than this value. The activation volume obtained for the pressure dependent phase of the blue shift was 43±11 mL mol−1. This activation volume decreased at 40 °C. The temperature dependence of the processes was analyzed at atmospheric pressure between 10 °C and 40 °C. The activation energy of the processes was calculated using Arrhenius plot. The activation energy of the blue shift was 98±20 kJ mol−1.
Chlorophyll-a content is widely used as an indicator of the quality of freshwater bodies. Quantif... more Chlorophyll-a content is widely used as an indicator of the quality of freshwater bodies. Quantification of chlorophyll-a is a routine procedure in the test laboratories of water works, and in research laboratories. Although attempts have been made to standardise the measurement procedure, there are nonetheless many procedures currently in use. This work is focused on a careful re-examination of the
In early spring 2000, two incidents of bursting dams int he mines Baia Mare and Baia Borsa (Roman... more In early spring 2000, two incidents of bursting dams int he mines Baia Mare and Baia Borsa (Romania) produced peak amounts of cyanide (32 mg 1(-1)) and heavy metals (mostly lead [2.9 mg 1(-1) in April], copper [18 mg 1(-1) in February and 0.86 mg 1(-1) in April] and zinc [0.95 mg 1(-1) in February and 2.9 mg 1(-1) in April] – data at the Romanian-Hungarian border section). A major fish kill and severe damage of benthos populations resulted. The aim of this study was to investigate the impact of the accident on planktonic and periphytic algae. Apart from detailed taxonomic information, diversity, evenness and diatom indices, chlorophyll-a analysis, X-ray fluorescence spectroscopy (TXRF), spectral analysis and SEM were applied. While transient damage of periphyton, especially the sensitive Chladophora glomerata, could be detected in the River Tisza, the phytoplankton did not respond. Flooding may have prevented effects by dilution. The problems related to algae as suitable biota for immediate spill effects are discussed.
The relationship between the structural and functional changes of the photosynthetic apparatus in... more The relationship between the structural and functional changes of the photosynthetic apparatus in the flower bud of Lilium longiflorum during chloroplast–chromoplast transition was examined. Compared with green petals, there was a five‐fold increase of the carotenoid content in yellow petals, whereas the chlorophyll content decreased five‐fold. Absorption and emission fluorescence spectra of chromoplasts indicated that newly synthesized carotenoids were not associated with photosystem II (PSII) photochemistry. The maximum quantum yield in the remaining PSII reaction centers remained constant during the chromoplast formation, whereas the photosynthetic electron transport beyond PSII became inhibited, as indicated by a marked decrease of the O2 evolution capacity, of the photochemical quenching of chlorophyll‐a fluorescence and of the operational quantum yield of photosynthetic electron transport. Deconvoluted fluorescence emission spectra indicated a more rapid degradation of photosystem I (PSI) complexes than of PSII during chromoplast formation. Compared with green petals, the spillover between PSII and PSI decreased by approximately 40% in yellow petals. Our results indicate that during chloroplast–chromoplast transition in the flower bud of L. longiflorum, PSII integrity was preserved longer than the rest of the photosynthetic apparatus.
Pioneering investigations of the chlorophyll biosynthesis have shown that the knowledge of the pr... more Pioneering investigations of the chlorophyll biosynthesis have shown that the knowledge of the primary chemical structure of chlorophylls and their precursors is not nearly enough for understanding of the process of this biosynthesis. This is especially true for the final steps of this process; a large body of data has been accumulated about the complicated spectral phenomena during the phototransformation of protochlorophyllide (PChlide) into chlorophyllide-a (Chlide-a) and the phytilization process (see for review l). This, together with the spectral multiplicity of PChlide must be in connection with the differencies in the molecular interactions of the PChlide molecules and with the changes of these interactions (2,3).
Aggregation and spectroscopic properties of protochlorophyll were investigated in solid films and... more Aggregation and spectroscopic properties of protochlorophyll were investigated in solid films and in Triton X-100 detergent micelles. The protochlorophyll form with absorption maximum at 650 nm appeared in solid films treated with vapour of acetone or water as well in detergent micelles. In addition to this form, several long-wavelength forms were also found especielly in water vapour treated solid films. While the 650 nm and the 676 nm forms had intense CD signals — with positive Cotton effects around 650 nm — another long-wavelength forms were optically inactive. The structural reasons of the differences of spectroscopic properties of protochlorophyll forms are discussed.
ABSTRACT We describe Chloroparva pannonica Somogyi, Felföldi & Vörös gen. et sp. nov., a ... more ABSTRACT We describe Chloroparva pannonica Somogyi, Felföldi & Vörös gen. et sp. nov., a new trebouxiophycean picoplanktonic alga isolated from a turbid, shallow soda pan in Hungary. The cells are spherical to oval, less than 2 mm in diameter, with simple ultrastructure typical to small green algae. Cells divide by autosporulation, forming two daughter cells per autosporangium. Cell wall structure consists of an outer trilaminar layer, an inner microfibrillar layer and an electron transparent layer covering the plasma membrane. The trilaminar layer of the mother cell wall often persists around the autospores. Typical chlorophyte pigments have been found, including chlorophyll a and b and lutein as the dominant carotenoid. The main fatty acid was oleic acid. The phylogenetic position of the new chlorophyte confirms the proposal of a new genus within the Trebouxiophyceae. Based on its 18S rRNA gene sequence, this isolate is distantly related to Nannochloris eucaryotum UTEX 2502, Chlorella minutissima C-1.1.9 and C. minutissima SAG 1.80 (# 97.6% 18S rRNA gene pairwise similarities).
Short-wavelength protochlorophyllide forms and their phototransformation in epicotyl of pea (Pisu... more Short-wavelength protochlorophyllide forms and their phototransformation in epicotyl of pea (Pisum sativum)
Abstract The relationship between the structural and functional changes of the photosynthetic app... more Abstract The relationship between the structural and functional changes of the photosynthetic apparatus in the flower bud of Lilium longiflorum during chloroplast–chromoplast transition was examined. Compared with green petals, there was a five-fold increase of the carotenoid content in yellow petals, whereas the chlorophyll content decreased five-fold. Absorption and emission fluorescence spectra of chromoplasts indicated that newly synthesized carotenoids were not associated with photosystem II (PSII) photochemistry. The maximum quantum yield in the remaining PSII reaction centers remained constant during the chromoplast formation, whereas the photosynthetic electron transport beyond PSII became inhibited, as indicated by a marked decrease of the O2 evolution capacity, of the photochemical quenching of chlorophyll-a fluorescence and of the operational quantum yield of photosynthetic electron transport. Deconvoluted fluorescence emission spectra indicated a more rapid degradation of photosystem I (PSI) complexes than of PSII during chromoplast formation. Compared with green petals, the spillover between PSII and PSI decreased by approximately 40% in yellow petals. Our results indicate that during chloroplast–chromoplast transition in the flower bud of L. longiflorum, PSII integrity was preserved longer than the rest of the photosynthetic apparatus.
Unlike etiolated leaves, epicotyls contain the majority of protochlorophyllide (Pchlide) in monom... more Unlike etiolated leaves, epicotyls contain the majority of protochlorophyllide (Pchlide) in monomer state emitting at 629 and 636 nm at 77 K. The longer wavelength, 644 and 655 nm emitting forms are in small quantities. Flash illumination converts only a small amount of Pchlide. Dark-grown epicotyls can be greened with continuous light of low irradiance only; natural sunlight causes bleaching of the pigments, loos of turgor and wilting. In this work, details of the photosensitivity were studied on intact epicotyls and in their homogenates. Under illumination, an increased amount of water was found in the intracellular spaces in stereo microscopic studies and light activated water-loss of the epicotyls was measured with a potometer. Immediately after preparation, the spectral properties and the photochemical activity of the homogenates were identical to those of intact epicotyls. The bleaching of the samples could be prevented with Na-ascorbate. When homogenates were stored at ? 20 °C for 4 days, the amplitude of the emission band at 636 nm decreased while the 655 nm band increased. Flash illumination caused full photoconversion of this latter form into chlorophyllide emitting at 692 nm. The efficiency of this process was higher than that of intact epicotyls. The light stress reactions, i.e. bleaching and water loss, suggest a free-radical chain reaction process in vivo, which can be stopped with free-radical trap. The spectral changes at ? 20 °C refer to the aggregation of POR subunits, which can be the reason of the increased phototransformation and decreased photosensitivity.
Photoreduction and interconversion processes of different protochlorophyllide complexes were stud... more Photoreduction and interconversion processes of different protochlorophyllide complexes were studied in epicotyl segments of dark-germinated pea (Pisum sativum L.) seed- lings illuminated with low-intensity white or 632.8 nm laser light. Analyses of 77 K fluorescence emission spectra showed the direct phototransformation of the monomer, 636 nm emitting com- plex. The 629 nm emitting complex containing also monomer pigment, regenerated all longer wavelength, flash-photoactive complexes. A dynamic transformation of the protochlorophyllide complexes was also detected during the illumination and/or the subsequent dark-incubation. On the basis of these results, the protochlorophyllide phototransformation schemes can be completed with new pathways.
The photoreduction and photooxidation processes of different protochlorophyll(ide) forms were stu... more The photoreduction and photooxidation processes of different protochlorophyll(ide) forms were studied in the innermost leaves of cabbage (Brassica oleracea var. capitata L.) under monochromatic irradiations. Room-temperature fluorescence emission spectra were measured from the same leaf spots before and after illumination to follow the wavelength dependence of the photochemical reactions. Short-wavelength light of 7 µmol photons m(-2) s(-1) (625-630 nm) provoked mainly bleaching, and longer wavelengths (630-640 nm) caused both bleaching and photoreduction, while above 640 nm resulted in basically photoreduction. When bleached leaves were kept in darkness at room temperature, all protochlorophyll(ide) forms regenerated during 72 h. Oxygen-reduced environment decreased the extent of bleaching suggesting the involvement of reactive oxygen species. These results confirm that the short-wavelength, 628 nm absorbing, and 633 nm emitting protochlorophyll(ide) form in etiolated cabbage leaves sensibilizes photooxidation. However, the 628 nm light at low intensities stimulates the photoreduction of the longer wavelength protochlorophyllide forms. Kinetic measurements showed that photoreduction saturates at a low PFD (photon flux density) compared to bleaching, suggesting that the quantum yield of photoreduction is higher than that of bleaching.
Advances in High Pressure Bioscience and Biotechnology II, 2003
In dark-grown higher plants the chlorophyll biosynthetic pathway stops at protochlorophyllide bec... more In dark-grown higher plants the chlorophyll biosynthetic pathway stops at protochlorophyllide because the enzyme, NADPH-pchlide oxidoreductase (POR), responsible for the transformation of pchlide into chlorophyllide (chlide) requires light for catalysis. As a consequence, the transformation of pchlide into chlorophyllide can be triggered with illumination in dark-grown plants. The newly formed chlorophyllide-enzyme complexes undergo a spectral blue shift. The photoreduction and the blue spectral shift were studied in homogenates prepared from etiolated wheat leaves using fluorescence spectroscopy at pressures up to 400 MPa. The kinetic curves of photoreduction were fitted with the sum of two exponential functions. The activation volumes were calculated from the pressure dependence of the reaction rate constants of the exponential curves at 20 °C and 40 °C. The two activation volumes corresponding to the two processes linked to the photo-transformation of pchlide were 1.8±1.2 mL mol−1 and 2.9±0.5 mL mol−1 at 20 °C, and both activation volumes increased with increasing temperature. The blue shift showed strong pressure dependence below 100 MPa at 20 °C and was almost stopped at pressures higher than this value. The activation volume obtained for the pressure dependent phase of the blue shift was 43±11 mL mol−1. This activation volume decreased at 40 °C. The temperature dependence of the processes was analyzed at atmospheric pressure between 10 °C and 40 °C. The activation energy of the processes was calculated using Arrhenius plot. The activation energy of the blue shift was 98±20 kJ mol−1.
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