In vivo estimation of pigment composition and optical absorption cross-section by spectroradiometry in four aquatic photosynthetic micro-organisms (original) (raw)
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The photobiological response of an isolate of the prymnesiophyte Chrysochromulina polylepis, obtained from a bloom in the Skagerrak in May-June 1988, was evaluated with respect to pigment composition, spectral dependence of light harvesting, and photosynthetic parameters of cultures grown at 75 to 120 gm01 m-2 S-' irradiance, 16 h day length and 15°C. Results were compared to similarly grown cultures of the diatom Skeletonerna costatum that appeared before and after the C. polylepis bloom. Chl a-specific absorption of light ("a,) and chl a-specific absorption of quanta transported to photosystem 11, estimated by means of a scaled fluorescence excitation spectrum ("F), were 1.7 to 2.1 times larger in C. polylepis than in S. costatum in the visible spectrum. C. polylepis harvested blue-green light (450 to 500 nm) particularly efficiently. This is related to a high proportion of 19'hexanoyloxyfucoxanthin and chl c3 relative to chl a. Nonetheless, both C. polylepis and S. costatum absorb light more efficiently in 'clearest' blue ocean water than in 'clearest' green coastal water according to calculations based on spectrally corrected absorbed quanta transported to photosystem I1 ("F). Carbon-specific light absorption was about the same in the 2 species since the chl a : C ratio in S. costatum was twice as high as in C. polylepis. C. polylepis had a much smaller maximum carbon uptake (P:) than S. costatum. Differences between the 2 species in terms of photosynthetic parameters, pigment composition, and spectral characteristics normalized to chl a, carbon, and cell are discussed.
Analysis of the red absorption band of chlorophyll a in vivo
Biochimica et biophysica acta, 1966
A precise and sensitive integrating spectrophotometer has been constructed in the shape of a dodecahedron with one photoelectric cell on each side. With the help of this instrument and a computer, the red chlorophyll a absorption band of algae and chloroplasts was resolved (after subtracting the chlorophyll b band) into two Gaussian components, with peaks at 668 and 683 nm**. The half-width of the twoband envelope is 32 nm; the half-width of each component, about 18 nm. In the bluegreen alga, Anacystis and the red alga, Porphyridium (both containing no chlorophyll b), the two-component bands seem to be in the same positions, but are considerably wider. (However, preliminary analysis suggests that the red band in Anacystis can be interpreted instead as the sum of three components-two belonging to chlorophyll a, and a third one probably due to allophycocyanin.) The relative heights of the two chlorophyll a components vary, in all plants used, only between o. 7 and o. 9, the 668-nm band always being the weaker one. Broadening of chlorophyll a absorption curves by the so-called "sieve effect" may to some extent change the analysis presented here, by causing the component bands in vivo to deviate from the Gaussian shape; this effect calls for further investigation but is unlikely to affect the qualitative conclusions. A comparison of the absorption spectrum so analyzed with that of the "Pigment systems I and II" (DuYsENS, I~'REXCH et al.) suggests that in Chlorella, a large portion of chlorophyll a 668 nm belongs, together with a large part of chlorophyll b, to System II, while a large part of chlorophyll a 683 nm must be identified with System I, although some of it probably belongs to System II. The simple identification of chlorophyll a 668 nm with System II, and chlorophyll a 683 nm with System I, as previously suggested, appears to be untenable. In red and blue-green algae, larger parts of both chlorophyll a 668 nm and chlorophyll a 683 nm seem to belong to System I. * This work is based on Ph.D. thesis of C. N'. CEDERSTRAND (1965). *" The term "nanometer" (nm) is used for lO-9 cm instead of millimicron (m/~).
Journal of Photochemistry and Photobiology B: Biology, 1999
The effect of ultraviolet (UV) radiation on thallus absorption, package effect, the concentration of photosynthetic pigments, photosynthetic oxygen production and effective quantum yield has been studied in the intertidal red macroalga Porphyru umbilicalis in the laboratory. High doses of UV-A and UV-B radiation result in a rapid decrease of thallus absorption and, after a 6 h exposure, total absorption is reduced to 25% of the initial value. Moreover, significant differences in the absorption peaks of the main pigments are found: while chlorophyll a (Chl a) and phycocyanin absorption peaks decrease by 65-67%, carotenoids and phycoerythrin (PE) peaks decrease by 75-82%. Uncoupling of the transfer of energy between PE and Chl a by UV is revealed by a gradual increase of fluorescence of PE up to 11 h of exposure, followed by a subsequent decrease of fluorescence of the PE, in parallel with the photobleaching of the pigments. Thalli with higher pigment concentration present a greater sensitivity to UV radiation, as revealed by a more pronounced decrease in total thallus absorption, oxygen production and effective quantum yield, and a less effective recovery under low irradiation. Exposure of the thalli to artificial UV radiation in an experimental chamber with spectra and doses more similar to those of the natural environment reveals that PAR + LJV-A radiation promotes a gradual increase of the total absorption over 24 h; in contrast, PAR + UV-A + UV-B induces a significant decrease of the thallus absorption. However, the concentration in vitro of Chl a, carotenoids and biliproteins does not change in any of these light treatments. The spectrally averaged in vivo absorption cross section normalized to Chl a (a*) increases after 24 h in PAR + LJV-A, but it does not change in PAR and PAR + UV-A+UV-B, indicating that the degree of packing of the pigments in the membranes of the thylakoids (package effect) is decreased by PAR + UV-A, but that the reverse is induced by PAR + UV-A + UV-B. It is proposed that UV-A radiation induces an enhancement of the efficiency of light capture mediated by a relaxation of pigment packing in the light-harvesting antennae of this intertidal macroalga, while the reverse is promoted by UV-B radiation. 0 1999 Elsevier Science S.A. All rights reserved.
The influence of phytoplankton photoacclimation and adaptation to natural growth conditions on the chlorophyll a-specific in vivo absorption coefficient (a* ph ) was evaluated for samples collected in estuarine, coastal and oceanic waters. Despite an overall gradient in the physio-chemical environment from estuaries, over coastal, to oceanic waters, no clear relationships were found between a* ph and the prevailing light, temperature, salinity and nutrient concentrations, indicating that short-term cellular acclimation was of minor importance for the observed variability in a* ph . The clear decline in a* ph from oceanic, over coastal, to estuarine waters was, however, strongly correlated with an increase in cell size and intracellular chlorophyll a (chl a) content of the phytoplankton, and a reduction of photosynthetic carotenoids relative to chl a. Variations in photoprotective carotenoids relative to chl a seemed to be of minor importance for the variability in a* ph . In addition, significant differences in phytoplankton composition and abundance were observed, primarily driven by an increase in the abundance of diatoms, which furthermore correlated with increasing pigment packaging and decreasing a* ph . The observed differences in a* ph were, therefore, primarily driven by longerterm adaptations of the phytoplankton community. Our data suggests that an overall increase in nutrient loading from oceanic to estuarine waters increases phytoplankton abundance and favors larger sized species, particularly within the diatoms. These changes eventually decrease a* ph through a rise in the package effect and a lower abundance of photosynthetic carotenoids relative to chl a.
Marine Ecology Progress Series, 1999
The photosynthetic prokaryote Prochlorococcus appears to have a high capacity to modify its physiological and optical properties in response to changes in available irradiance. In order to study the time scale of variations in light absorption induced by photoacclimation, 2 strains (MED. clone CCMP 1378, and SARG, unialgal strain) were grown in batch cultures at high (56.7 pmol quanta m-' s') or low (8.4 pmol quanta m-* s-') irradiance. Then the temporal changes over 3 to 4 d in spectral absorption coefficients, pigment composition, cell number density and size distribution were followed for cultures transferred from high to low irradiance, and vice versa. Both strains experienced significant changes in their divinyl-chlorophyll a-specific absorption coefficients (a') in response to the transfers. For the MED strain, photoacclimation appeared to be achieved within about 40 h (covering 2 cell generations) for the low to high irradiance transfer, while 3 to 4 d (corresponding to 1 doubling of the population) were necessary for the high to low irradiance transfer. For the SARG strain transferred from high to low irradiance, in spite of a rapid change in absorption during the first 25 h (i.e. within the same cell generation), full photoacclimation was not achieved after 3 d. The efficiency factors for absorption, c&i,, and the a'(X) coefficients, were reconstructed from theory at the different photoaccliiation stages from the cell characteristics, i.e. intracellular concentrations of the various pigments and cell size distribution. This permitted the determination of the parameters which are mainly responsible for the observed changes. The O,(h) values (and therefore the package effect) are enhanced at low irradiance by 2 effects resulting from photoacclimation: the increase of the intracellular concentration of divinylchlorophyll a, and (for the SARG strain only) the increase of the intracellular concentration of chlorophyll b. In addition, theqresence of zeaxanthin, in stable amounts within the cells whatever the irradiance. enhances the Q,(h) values for all light conditions, and thus 'moderates' its variations with irradiance. Contrary to what is commonly admitted because of its tiny size, the absorption efficiency of Prochlorococcus (per pigment unit) is not always maximal, but can be reduced by 20 to 25 % at low irradiances, such as those prevailing in the lower part of the euphotic zone. This reduction directly affects the amount of absorbed energy usable for photosynthesis. KEY WORDS: Prochlorococcus. Prochlorophyta Optical properties. Absorption Photoacclimation 'X 'E-mail: brfcaud&bs-vlfr.fr oceanic waters, and to account for a significant part of the biomass as well as the primary production, particularly in oligotrophic and mesotrophic ecosystems (e.g. Goericke & Welschmeyer 1993, Campbell et al. 1994; see also review by Partensky et al. 1999). Prochlorococcus is observed over a wide irradiance range, approximately 1 to 1500 urn01 quanta m-* s-' (Parten-0 Inter-Research 1999
Marine Ecology Progress Series, 1992
The photobiological response of an isolate of the prymnesiophyte Chrysochromulina polylepis, obtained from a bloom in the Skagerrak in May-June 1988, was evaluated with respect to pigment composition, spectral dependence of light harvesting, and photosynthetic parameters of cultures grown at 75 to 120 gm01 m-2 S-' irradiance, 16 h day length and 15°C. Results were compared to similarly grown cultures of the diatom Skeletonerna costatum that appeared before and after the C. polylepis bloom. Chl a-specific absorption of light ("a,) and chl a-specific absorption of quanta transported to photosystem 11, estimated by means of a scaled fluorescence excitation spectrum ("F), were 1.7 to 2.1 times larger in C. polylepis than in S. costatum in the visible spectrum. C. polylepis harvested blue-green light (450 to 500 nm) particularly efficiently. This is related to a high proportion of 19'hexanoyloxyfucoxanthin and chl c3 relative to chl a. Nonetheless, both C. polylepis and S. costatum absorb light more efficiently in 'clearest' blue ocean water than in 'clearest' green coastal water according to calculations based on spectrally corrected absorbed quanta transported to photosystem I1 ("F). Carbon-specific light absorption was about the same in the 2 species since the chl a : C ratio in S. costatum was twice as high as in C. polylepis. C. polylepis had a much smaller maximum carbon uptake (P:) than S. costatum. Differences between the 2 species in terms of photosynthetic parameters, pigment composition, and spectral characteristics normalized to chl a, carbon, and cell are discussed.
Marine Biology, 2006
Chl a and C-normalized pigment ratios were studied in two dinophytes (Prorocentrum minimum and Karlodinium micrum), three haptophytes (Chrysochromulina leadbeateri, Prymnesium parvum cf. patelliferum, Phaeocystis globosa), two prasinophytes (Pseudoscourfieldia marina, Bathycoccus prasinos) and the raphidophyte Heterosigma akashiwo, in low (LL, 35 lmol photons m À2 s À1 ) and high light (HL, 500 lmol photons m À2 s À1 ). Pigment ratios in LL and HL were compared against a general rule of photoacclimation: LL versus HL ratios ‡1 are typical for light-harvesting pigments (LHP) and <1 for photoprotective carotenoids. Peridinin, prasinoxanthin, gyroxanthin-diester and 19¢-butanoyloxy-fucoxanthin were stable chemotaxonomic markers with less than 25% variation between LL versus HL Chl a-normalized ratios. As expected, Chls exhibited LL/HL to Chl a ratios >1 with some exceptions such as Chl c 3 in P. globosa and MV Chl c 3 in C. leadbeateri. LL/HL to Chl a ratios of photosynthetic carotenoids were close to 1, except Hex-fuco in P. globosa (four-fold higher Chl a ratio in HL vs LL). Although pigment ratios in P. globosa clearly responded to the light conditions the diadinoxanthin-diatoxanthin cycle remained almost unaltered at HL. Total averaged pigment and LHP to C ratios were significantly higher in LL versus HL, reflecting the photoacclimation status of the studied species. By contrast, the same Chl a-normalized ratios were weakly affected by the light intensity due to covariation with Chl a. Based on our data, we suggest that the interpretation of PPC and LHP are highly dependent on biomass normalization (Chl a vs. C).
Specific in vivo absorption coefficient of chlorophyll a at 675nm
Limnology and Oceanography, 1987
Spectral absorption of phytoplankton from cultures and natural samples was measured by means of an integrating-sphere photometer. Measurements on suspension yielded specific absorption coefficients for healthy phytoplankton cultures in collimated light at 675 nm between 0.007 and 0.0 13 m2 (mg Chl a) I. These values were independent of cell density and cell wall material. Natural samples of Kiel harbor water yielded specific absorption coefficients at 675 nm of 0.009 and 0.017 m2 (mg Chl a)-I. The specific absorption coefficients in suspension were dependent on the optical properties of the individual cells (packaging effect), decreasing (ca. l/r) with increasing cell size (r radius) and increasing chlorophyll a content per cell as predicted by theory, but are significantly lower than theoretically expected. Comparison with published values shows that specific absorption coefficients of cell suspensions are often overestimated, presumably because of methodological problems.
Journal of Applied Phycology, 2003
The transfer of laboratory cultures of H. pluvialis to high irradiance outdoors caused a substantial decline in the maximum quantum yield of photosystem II (PSII), from 0.65 in the morning to 0.45 at midday, as measured by the ratio of variable to maximum fluorescence yields (F v /F m), and a steep rise in non-photochemical quenching (NPQ). Chlorophyll fluorescence induction curves of morning samples showed a clear I-step, reflecting a certain PSII heterogeneity. Single turnover flash measurements on samples taken from the outdoor photobioreactor in the middle of day showed an increase in the reoxidation time constant of the reduced plastoquinone Q A − , i.e., the time required for electron transfer from the primary plastoquinone acceptor of PSII Q A − to the secondary plastoquinone acceptor Q B. Photosynthesis rates were almost constant during the day. Along with the increase in nonphotochemical quenching, there was a slight increase in zeaxanthin and antheraxanthin contents and decrease in violaxanthin, showing the presence of an operative xanthophyll cycle in this microalga. A marked increase of secondary carotenoids was found at the end of the first day of exposure to sunlight, mainly astaxanthin monoester, which reached 15.5% of the total carotenoid content. Though cells turned reddish during the second day, the decline in the fluorescence parameter F v /F m in the middle of the day was less than during the first day, and there was no further increase in the value for NPQ. Similar behaviour was observed during the third day when the culture was fully red. After four days of exposure to sunlight, the dry weight reached 800 mg L −1 and the concentration of secondary carotenoids (81% astaxanthin monoester) reached 4.4% dry weight. Abbreviations: F o , F v , F m-minimum, variable and maximum fluorescence yields in dark-adapted cultures, F, FЈ m-steady-state and maximum fluorescence yields in light-adapted cultures, F v /F m-maximum photochemical quantum yield of photosystem II, NPQ-Stern-Volmer quenching, (F m /FЈ m)−1, DTT-dithiothreitol, Q A , Q Bprimary and secondary plastoquinone acceptors of photosystem II, PSII-photosystem II
Journal of Applied Phycology, 2009
The relationships between pigment (carotenoid and chlorophyll) content with accumulation of total fatty acids (TFA) and arachidonic acid (AA) were studied in the green microalga Parietochloris incisa (Trebouxiophyceae, Chlorophyta) grown under different PFDs (35, 200, and 400 μmol photons m −2 s −1 ) and nitrogen availabilities. The growth of P. incisa under higher light and nitrogen deficiency was accompanied by accumulation of FA, an increase in carotenoid and a decline in chlorophyll content. It was found that the carotenoid-to-chlorophyll ratio (but not the individual pigment content) correlates closely with the volumetric content of both TFA and AA. Analysis of scatteringcompensated absorption spectra of P. incisa suspensions revealed their tight relationship in the blue-green range of the spectrum with the carotenoid-to-chlorophyll ratio, TFA, and AA content. These findings allowed the development of algorithms for the non-destructive assay of TFA and AA in cell suspensions in the ranges of 0.09-3.04 and 0.04-1.7 μg mL −1 , with accuracy of 0.06 and 0.01 μg mL −1 , respectively, via analytically measured carotenoid-to-chlorophyll ratio and using the ratio of absorption coefficients at 510 and 678 nm, with accuracy of 0.07 and 0.02 μg mL −1 , respectively. The feasibility of obtaining essential spectral information con-cerning the physiological condition of P. incisa using a standard spectrophotometer is also shown.