Biomarkers
Lipids in deep-sea Xenophyophoria
(Rhizopoda, Protozoa)
J. Laureillard (1) , J. Kohn (1) , L. Méjanelle (1) , M. Sibuet (2) , A. Saliot (1)
(1) Université de Paris 6, laboratoire de physique et chimie marines,
case 134, 4 place Jussieu, 75252 Paris Cedex 05, France - jlaureil@ccr.jussieu.fr
(2) Ifremer Brest, Dro/ep, BP 70, 29280 Plouzané, France
In the framework of the JGOFS-France programme, several sediment
samples were recovered by use of a boxcorer (modified USNEL type)
and a multicorer during the EUMELI 2 cruise, in order to investigate
the origin and fate of organic matter in the north-east tropical Atlantic.
The general aim of rhis cruise was to understand factors governing the
cycle of carbon and the role of the various benthic communities m the
recycling of organic matter. A special attention was paid in order ro
recover the sediment water interface without perturbation. Therefore,
it was possible to retrieve fragile xenophyophores in especially good
conditions of preservation, at a mesotrophic site. Xenophyophores are
large deep-sea protists in which the body and agglutinated particles
resulting from the animal digestion are covered by a voluminous test.
In spite of a wide geographic distribution, due to the great fragility of
their test, little information is available on their morphology, ecology
and nothing about their biochemical composition. Consequently, lipid
analyses were performed on these well-preserved animals with the
surficial sediment underneath, and on another surficial mesotrophic
sediment deprived of these protists, as a reference. Lipids possess molecular characteristics which can give an insight into the sources and
alterations affecting organic matter in the ocean. Indeed, lipid distributions often vary among different groups of biota: prokaryotes, phytoplankton, zooplankton and vascular plants, and it is that feature
that allows use of lipids as biomarkers.
The distribution of lipid classes was obtained by use of the Iatroscan
technique and several classes were investigated for fatty acids, hydrocarbons and sterols. Of special interest is the class of phospholipids,
important constituents of membranes, which contain the fatty acid
biomarkers, for living organisms.
These lipid analyses emphasize some characteristics of xenophyophores
and of the commensal bacterial populations compared with the neighbour sediment and the associated bacterial assemblage. It was also an
opportunity to compare the quantification of lipid class contents, using
Iatroscan or thin-layer chromatography-GC methods.
103
Lipids in deep-sea Xenophyophoria
(Rhizopoda, Protozoa)
J. Laureillard (1) , J. Kohn (1) , L. Méjanelle (1) , M. Sibuet (2) , A. Saliot (1)
(1) Université de Paris 6, laboratoire de physique et chimie marines,
case 134, 4 place Jussieu, 75252 Paris Cedex 05, France - jlaureil@ccr.jussieu.fr
(2) Ifremer Brest, Dro/ep, BP 70, 29280 Plouzané, France
In the framework of the JGOFS-France programme, several sediment
samples were recovered by use of a boxcorer (modified USNEL type)
and a multicorer during the EUMELI 2 cruise, in order to investigate
the origin and fate of organic matter in the north-east tropical Atlantic.
The general aim of rhis cruise was to understand factors governing the
cycle of carbon and the role of the various benthic communities m the
recycling of organic matter. A special attention was paid in order ro
recover the sediment water interface without perturbation. Therefore,
it was possible to retrieve fragile xenophyophores in especially good
conditions of preservation, at a mesotrophic site. Xenophyophores are
large deep-sea protists in which the body and agglutinated particles
resulting from the animal digestion are covered by a voluminous test.
In spite of a wide geographic distribution, due to the great fragility of
their test, little information is available on their morphology, ecology
and nothing about their biochemical composition. Consequently, lipid
analyses were performed on these well-preserved animals with the
surficial sediment underneath, and on another surficial mesotrophic
sediment deprived of these protists, as a reference. Lipids possess molecular characteristics which can give an insight into the sources and
alterations affecting organic matter in the ocean. Indeed, lipid distributions often vary among different groups of biota: prokaryotes, phytoplankton, zooplankton and vascular plants, and it is that feature
that allows use of lipids as biomarkers.
The distribution of lipid classes was obtained by use of the Iatroscan
technique and several classes were investigated for fatty acids, hydrocarbons and sterols. Of special interest is the class of phospholipids,
important constituents of membranes, which contain the fatty acid
biomarkers, for living organisms.
These lipid analyses emphasize some characteristics of xenophyophores
and of the commensal bacterial populations compared with the neighbour sediment and the associated bacterial assemblage. It was also an
opportunity to compare the quantification of lipid class contents, using
Iatroscan or thin-layer chromatography-GC methods.
103