Preliminary characterisation of the blue-green pigment “marennine” from the marine tychopelagic diatom Haslea ostrearia (Gaillon/Bory) Simonsen

Abstract

Haslea ostrearia is a common marine tychopelagic diatom which has the particularity of synthesizing a blue-green hydrosoluble pigment called "marennine". This pigment, when released into the external medium, is known to be responsible for the colour of oyster gills. Here we present results for main biophysical and biochemical characteristics of pure intra-and extracellular marennine. Tests for chemical determination show that the nature of the two forms of marennine cannot be distinguished and could be related to a polyphenolic compound. Nevertheless, based on spectral properties and the molecular weight, which is about 10751 ± 1 and 9893 ± 1 Da, for the intracellular and extracellular forms respectively, we assess that the pigment accumulated in the apex of the cell and the one released in the external medium have probably distinct molecular structures.

Method for the quantification of the blue-green pigment “marennine” synthesized by the marine diatom Haslea ostrearia (Gaillon/Bory) Simonsen using HPLC gel-filtration and photodiode-array detection

“…The concentrations of marennine were calculated from these spectra by applying the Beer-Lambert's law. The specific extinction coefficients used were those of pure marennine standards in 250 mmol L −1 NaHCO 3, pH 8, determined according to Pouvreau et al (2006b). By this method, marennine concentrations were evaluated as 0.426 g L −1 in CE and at 0.010 g L −1 in BW.…”

“…Nevertheless, little is yet known about the complete structure, synthesis and biological function of marennine (Neuville and Daste 1978;Schubert et al 1995;Tremblin and Robert 1996;Pouvreau et al 2006b). To advance these studies, a reliable and precise method to monitor and quantify marennine routinely is needed.…”

“…In contrast, the amount of marennine assayed in BW by spectrophotometric measurement represented about 65% of that obtained by gel-filtration HPLC-PDA analysis. In this case, owing to the dependence on pH and ionic strength of the marennine extinction coefficient (Robert et al 2002;Pouvreau et al 2006b), the difference can be ascribed mainly to culture conditions. Compared to CE, the contaminating fraction in BW is quite low and does not contain pigments.…”

“…Quartz cuvettes with a 1 cm path length were used. The concentration of marennine can be determined by using Beer-Lambert's equation : [C]=A 1max /ε 1max × l, where A 1max is the absorbance of the solution at the maximum light absorption wavelength in the red region, l is the cuvette path length, and ε 1max is the specific extinction coefficient of pure marennine in NaHCO 3 250 mmol L −1 , pH 8 (ε 672 =6.88 L g −1 cm −1 for IMn and ε 677 =12.13 L g −1 cm −1 for EMn), calculated according to Pouvreau et al (2006b). All tests were carried out in triplicate.…”

Haslea karadagensis(Bacillariophyta): a second blue diatom, recorded from the Black Sea and producing a novel blue pigment

“…It has been shown from previous studies (Pouvreau et al, 2006a) that the supernatant obtained from cultures of H. ostrearia is composed of an extracellular form of marennine with a molecular weight of 9893 AE 1 Da, which is actively secreted into the medium, plus some of the intracellular form, with a molecular weight of 10751 AE 1 Da, released after cell death. Because Pouvreau et al (2006a) demonstrated that pH has a bathochromic effect on the absorption spectrum of marennine, we excluded possible artefacts by controlling the pH of the supernatants from the two species before measurement. At pH 8.0, both absorption peaks, in the UV and visible regions, differed between filtered supernatants from the two diatom cultures.…”