The flattering of the absorption spectrum of suspensions, as compared to that of solutions

Duysens, L.N.M.

doi:10.1016/0006-3002(56)90380-8

Cited by 692 publications

(313 citation statements)

References 1 publication

Supporting

Mentioning

306

Contrasting

Unclassified

Order By: Relevance

“…1) can be explained by the package effect (or internal self-shading) of MAAs. Duysens (1956) demonstrated theoretically that the absorption spectrum of a substance contained in particles appears flattened when compared with the absorption of the same substance (same concentration) in solution. The flattening in the UV waveband likely depends on the shape and size of cells, but also on the composition and internal distribution of the UV absorbing compounds within the cells (as seen for pigments in the visible range; e.g.…”

Section: Discussionmentioning

confidence: 99%

Packaging of mycosporine-like amino acids in dinoflagellates

Laurion¹,

Blouin²,

Roy³

2004

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

Synthesis of mycosporine-like amino acids (MAAs) can significantly protect phytoplankton cells against damaging ultraviolet (UV) radiation, depending on the concentration, type and cellular distribution of these UV sunscreens. We addressed the hypothesis that MAAs are concentrated around UV-sensitive organelles for improved efficiency, thereby increasing their 'package effect'. This was investigated for 2 species of MAA-producing dinoflagellates, with comparative analyses of a MAA-free diatom. Spectral absorbance of dinoflagellates suspended in their growth medium was relatively small throughout the MAA-absorbing region despite high concentrations of these compounds (determined by HPLC), suggesting that MAAs are highly packaged in intact cells. The measured in vivo absorbance of suspended and filtered phytoplankton cells revealed an extracellular release of water-soluble MAAs during freezing. The release of MAAs upon thawing enabled the calculation of an MAA packaging index based on the comparison between absorption characteristics before (MAAs inside cells in suspension) and after freezing (MAAs released from cells on thawed filters). Additionally, MAA packaging was evaluated from the reconstruction of absorption spectra from the individual MAA concentration. Consistent with our hypothesis, the results showed that UV absorption was up to 80% lower in the intact cells relative to the MAAs dissolved in solution. These results imply a high degree of MAA packaging in these dinoflagellates, that may increase the protection efficiency for specific cellular targets. KEY WORDS: Package effect · Photoprotection · MAAs · UV-absorbing compounds · Bio-optics · Alexandrium tamarense Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 279: [297][298][299][300][301][302][303] 2004 Pigment packaging has a major influence on the light harvesting efficiency of algal cells (Kirk 1994 and references therein). The absorption efficiency of phytoplankton is a non-linear function of pigment concentration, thylakoid arrangement and cell size (Berner et al. 1989, Nelson et al. 1993. A similar packaging effect for UV sunscreens could be of importance to MAAproducing phytoplankton. For UV sunscreens however, packaging can be viewed as effectiveness, since with equal investments, a large organism would benefit more than a small one. The bio-optical model developed by Garcia-Pichel (1994) indicates that MAAs should only be marginally effective at reducing UV radiation due to the short pathlength characteristic of relatively small phytoplankton cells (assuming a homogeneous cytoplasmic distribution of MAAs). However, the localization of MAAs around UV-sensitive organelles (packaged MAAs) might increase their efficiency, although this has not yet been assessed. MAA packaging has been suggested previously for the colonial prymnesiophyte Phaeocystis antarctica (Davidson & Marchant 1994, Moisan & Mitchell 2001. However, MAA concentrations observed in colonial prymnesiophytes appeared too h...

show abstract

Section: Discussionmentioning

confidence: 99%

Packaging of mycosporine-like amino acids in dinoflagellates

Laurion¹,

Blouin²,

Roy³

2004

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

show abstract

“…A series of papers derive essentially the same equation by different routes and arguments [1][2][3][4]10]. Using the symbols of Naqvi et al [10], the procedure is to calculate first the parameter α,…”

Section: Re-arrangement and Re-parameterisation Of Literature Equatiomentioning

confidence: 99%

“…The size of the flattening effect was first analysed in a classic paper by Duysens [1]. Since then there have been a series of approaches to modelling the effect [2][3][4][5][6][7][8][9][10][11][12][13][14], which are discussed in more detail in the Theory section.…”

Section: Introductionmentioning

confidence: 99%

Estimation of flattening coefficient for absorption and circular dichroism using simulation

Halling

2009

Analytical Biochemistry

View full text Add to dashboard Cite

The Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output. ABSTRACT.The absorbance and circular dichroism (CD) of suspensions is lower than if the same amount of chromophore were uniformly distributed throughout the medium. Several mathematical treatments of this absorption flattening phenomenon have been presented, using various assumptions and approximations. This paper demonstrates an alternative simulation approach, which allows relaxation of assumptions. On current desk-top computers the algorithm runs quickly with enough particles and light paths considered to get answers usually accurate to better than 3%. Results from the simulation agree with the most popular analytical model for 0.01 volume fraction of particles, showing that the extent of flattening depends mainly on the absorbance through a particle diameter. Unlike previous models, the simulation can show that flattening is significantly lower when volume fraction increases to 0.1, but higher if the particles have a size distribution. The simulation can predict the slope of the nearly linear relationship between flattening of CD and the absorbance of the suspension. This provides a method to correct experimental CD data, where volume fraction and particle size are known.

show abstract

“…and this effect cannot be completely ruled out in the case of the 'multi-pigment' method used here either. The flattening effect refers to the relative flattening of the absorption spectrum of partic1.e~ in suspension relative to that of the same material in solution (Duysens 1956). It depends on the particle size and shape and on the concentration of the absorbing material within the cells.…”

Section: Factors Influencing the Absorption Coefficientmentioning

confidence: 99%

“…The shape of the absorption spectrum of a phytoplankton population is determined mainly by its pigment composition and by the flattening effect of particles in suspension (Duysens 1956, Kirk 1983, Sathyendranath et al 1987. Changes in species composition and in physiological conditions affect the absorption properties of phytoplankton, and consequently Kd(h), since the latter depends on the absorption coefficient of phytoplankton, aph(h) (m-') (Kirk 1983, Smith et al 1989).…”

Section: Introductionmentioning

confidence: 99%

Absorption coefficient of phytoplankton:regional variations in the North Atlantic

Lutz¹,

Sathyendranath²,

Head³

1996

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

The effect of major pigments on the absorption characteristics of phytoplankton were evaluated by comparing the in vjvo absorption spectra of phytoplankton with pigment data obtained using high-performance liqu~d chromatography (HPLC) for samples of phytoplankton collected in the northwestern Atlantic Ocean, during spring. Four groups of spectra having distinct absorption characteristics and well-defined regional distributions were identified. The result of using general parameters to estimate the absorption coefficient of phytoplankton from any region, the 'general approach', was compared with the result of using specific parameters for each region, or the 'regional approach' Two methods of estlrnating the absorption coefficient were tested for each approach. These were: a 'slnglepigment' method (Prieur & Sathyendranath 1981, Limnol Oceanogr 26:671-689), and a 'multi-pigment' method (Hoepffner & Sathyendranath 1991, Mar Ecol Prog Ser 73:ll-23). It was shown that the regional approach performed better (<10% average error) than the general approach (~2 0 % average error). Nevertheless, the results given by the general approach could be acceptable for some applications. The multi-pigment and the single-pigment methods performed equally well in the context of the reglonal approach, whereas in the general approach, the s~ngle-pigment method gave better results than the multi-pigment method. Overall, it appears that part~tioning the oceans into regions according to their absorption characteristics should improve regional models of light transmission and the algorithms for detection of pigments by remote sensing.

show abstract

The flattering of the absorption spectrum of suspensions, as compared to that of solutions

Cited by 692 publications

References 1 publication

Packaging of mycosporine-like amino acids in dinoflagellates

Packaging of mycosporine-like amino acids in dinoflagellates

Estimation of flattening coefficient for absorption and circular dichroism using simulation

Absorption coefficient of phytoplankton:regional variations in the North Atlantic

Contact Info

Product

Resources

About