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

International audienceHaslea 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

Cell size-based, passive selection of the blue diatom Haslea ostrearia by the oyster Crassostrea gigas

International audiencePre-ingestive selection has been identified as a feeding mechanism of oysters that may influence their uptake of particles and microalgal cells. Oysters can feed specifically on the pennate diatom Haslea ostrearia, which produces the blue pigment marennine that is responsible for the greening of oysters. Because the size of particles or cells plays a significant role in the selection process, and given that diatoms experience a decrease in size as a consequence of vegetative reproduction, H. ostrearia consumption and marennine uptake might be influenced by pre-ingestive selection. We examined the role of H. ostrearia cell size in the selective feeding of Crassostrea gigas. Individual flow-through chambers were used to deliver mixtures of H. ostrearia of varying cell length to oysters. Inflow, outflow and pseudofaecal samples were collected from chambers during oyster feeding. Video-endoscopy was used to sample material in the dorsal and ventral particle tracts. Diatom cells counts showed that pseudofaeces contained on average larger cells than the ambient medium. However, proportions of the different populations of H. ostrearia in pseudofaeces were identical to those in the ventral tracts, indicating that no selection was performed by the labial palps. Video-endoscopy, plus imaging by scanning electron microscopy, of gills and labial palps revealed that only those larger H. ostrearia that were orientated dorsoventrally could enter the principal filaments (pfs) and then access the dorsal acceptance tract. These results show that for particles like Haslea cells with only one axis exceeding the width of the pfs, the selection on the oyster gills is passive and based on cell size

Cell size-based, passive selection of the blue diatom Haslea ostrearia by the oyster Crassostrea gigas

International audiencePre-ingestive selection has been identified as a feeding mechanism of oysters that may influence their uptake of particles and microalgal cells. Oysters can feed specifically on the pennate diatom Haslea ostrearia, which produces the blue pigment marennine that is responsible for the greening of oysters. Because the size of particles or cells plays a significant role in the selection process, and given that diatoms experience a decrease in size as a consequence of vegetative reproduction, H. ostrearia consumption and marennine uptake might be influenced by pre-ingestive selection. We examined the role of H. ostrearia cell size in the selective feeding of Crassostrea gigas. Individual flow-through chambers were used to deliver mixtures of H. ostrearia of varying cell length to oysters. Inflow, outflow and pseudofaecal samples were collected from chambers during oyster feeding. Video-endoscopy was used to sample material in the dorsal and ventral particle tracts. Diatom cells counts showed that pseudofaeces contained on average larger cells than the ambient medium. However, proportions of the different populations of H. ostrearia in pseudofaeces were identical to those in the ventral tracts, indicating that no selection was performed by the labial palps. Video-endoscopy, plus imaging by scanning electron microscopy, of gills and labial palps revealed that only those larger H. ostrearia that were orientated dorsoventrally could enter the principal filaments (pfs) and then access the dorsal acceptance tract. These results show that for particles like Haslea cells with only one axis exceeding the width of the pfs, the selection on the oyster gills is passive and based on cell size

Can the European abalone Haliotis tuberculata survive on an invasive algae? A comparison of the nutritional value of the introduced Grateloupia turuturu and the native Palmaria palmata, for the commercial European abalone industry

©. This manuscript version is made available under the CC-BY 4.0 license http://creativecommons.org/licenses/by/4.0/ This document is the Published/Accepted/Submitted Manuscript version of a Published Work that appeared in final form in [Journal of Applied Phycology]. To access the final edited and published work see[10.1007/s10811-015-0741-z

Greening effect on oysters and biological activities of the blue pigments produced by the diatom Haslea karadagensis (Naviculaceae)

International audienc

A new blue-pigmented hasleoid diatom, <i>Haslea provincialis</i>, from the Mediterranean Sea

International audienc

Marennine, Promising Blue Pigments from a Widespread Haslea Diatom Species Complex

In diatoms, the main photosynthetic pigments are chlorophylls a and c, fucoxanthin, diadinoxanthin and diatoxanthin. The marine pennate diatom Haslea ostrearia has long been known for producing, in addition to these generic pigments, a water-soluble blue pigment, marennine. This pigment, responsible for the greening of oysters in western France, presents different biological activities: allelopathic, antioxidant, antibacterial, antiviral, and growth-inhibiting. A method to extract and purify marennine has been developed, but its chemical structure could hitherto not be resolved. For decades, H. ostrearia was the only organism known to produce marennine, and can be found worldwide. Our knowledge about H. ostrearia-like diatom biodiversity has recently been extended with the discovery of several new species of blue diatoms, the recently described H. karadagensis, H. silbo sp. inedit. and H. provincialis sp. inedit. These blue diatoms produce different marennine-like pigments, which belong to the same chemical family and present similar biological activities. Aside from being a potential source of natural blue pigments, H. ostrearia-like diatoms thus present a commercial potential for aquaculture, cosmetics, food and health industries