Penetration of ultraviolet radiation in the marine environment. A review.

UV radiation (UVR) is a significant ecological factor in the marine environment that can have important effects on planktonic organisms and dissolved organic matter (DOM). The penetration of UVR into the water column is likely to change in the near future due to interactions between global warming and ozone depletion. In this study we report underwater instruments employed for the measurement of UVR and we review data dealing with the depth of UVR penetration in different oceanic areas including the open ocean, Antarctic waters and coastal waters.

Global production increased by spatial heterogeneity in a population dynamics model.

Spatial and temporal heterogeneity are often described as important factors having a strong impact on biodiversity. The effect of heterogeneity is in most cases analyzed by the response of biotic interactions such as competition of predation. It may also modify intrinsic population properties such as growth rate.

Systematics of Chaetognatha under the light of molecular data, using duplicated ribosomal 18S DNA sequences.

While the phylogenetic position of Chaetognatha has became central to the question of early bilaterian evolution, the internal systematics of the phylum are still not clear. The phylogenetic relationships of the chaetognaths were investigated using newly obtained small subunit ribosomal RNA nuclear 18S (SSU rRNA) sequences from 16 species together with 3 sequences available in GenBank. As previously shown with the large subunit ribosomal RNA 28S gene, two classes of Chaetognatha SSU rRNA gene can be identified, suggesting a duplication of the whole ribosomal cluster; allowing the rooting of one class of genes by another in phylogenetic analyses.

Characterization of unusual alkenones and alkyl alkenoates by electron ionization gas chromatography/mass spectrometry.

Unusual long-chain, diunsaturated alkenones and alkyl alkenoates exhibiting double bonds separated by three methylene units instead of the more usual five were characterized by electron ionization (EI) gas chromatography/mass spectrometry. In a first step, the positions of the double bonds of these compounds (isolated from Holocene Black Sea sediments) were confirmed after OsO4 treatment and silylation. Mass spectra of the resulting tetratrimethylsilyloxy derivatives allowed unambiguous determination of the positions of unsaturations.

Anaerobic Degradation of Hexadecan-2-one by a Microbial Enrichment Culture under Sulfate-Reducing Conditions.

A microbial enrichment culture from marine sediment was able to grow on hexadecan-2-one as the sole source of carbon and energy under sulfate-reducing conditions. Oxidation of the ketone involved carboxylation reactions and was coupled to sulfide production. This enrichment culture also grew on 6,10,14-trimethylpentadecan-2-one.

Three poorly known and rarely reported bucephalid species (Digenea) in fishes from the Western Mediterranean.

Three poorly known bucephalid species are described from off Corsica, in the Western Mediterranean Sea. Bucephalus gorgon (Linton, 1905) (syn. B.

Two species of the fish digenean genus Rhipidocotyle Diesing, 1858 (Bucephalidae) reported for the first time from European seas.

Two species of Rhipidocotyle are described from waters off the Scandola Nature Reserve, Corsica, France: these are the first records of these species from the Mediterranean Sea. R. capitata (Linton, 1940) from Auxis rochei and R.

Anaerobic n-alkane metabolism by a sulfate-reducing bacterium, Desulfatibacillum aliphaticivorans strain CV2803T.

The alkane-degrading, sulfate-reducing bacterium Desulfatibacillum aliphaticivorans strain CV2803T, recently isolated from marine sediments, was investigated for n-alkane metabolism. The total cellular fatty acids of this strain had predominantly odd numbers of carbon atoms (C odd) when the strain was grown on a C-odd alkane (pentadecane) and even numbers of carbon atoms (C even) when it was grown on a C-even alkane (hexadecane). Detailed analyses of those fatty acids by gas chromatography/mass spectrometry allowed us to identify saturated 2-, 4-, 6-, and 8-methyl- and monounsaturated 6-methyl-branched fatty acids, with chain lengths that specifically correlated with those of the alkane.

Electron ionization mass spectral fragmentation of cholestane-3beta,4alpha,5alpha-triol and cholestane-3beta,5alpha,6alpha/beta-triol bis- and tris-trimethylsilyl derivatives.

The electron ionization (EI) mass spectral fragmentation of the bis- and tris-trimethylsilyl derivatives of cholestane-3beta,4alpha,5alpha-triol, cholestane-3beta,5alpha,6beta-triol and cholestane-3beta,5alpha,6alpha-triol was investigated. The EI mass spectrum of the 3beta,4alpha-bis-trimethylsilyl derivative of cholestane-3beta,4alpha,5alpha-triol exhibits interesting fragment ions at m/z 142 and 332 resulting from the initial loss of TMSOH between the carbons 2 and 3 and subsequent retro-Diels-Alder (RDA) cleavage of the ring A. Trimethylsilyl transfer between the 4alpha- and the 5alpha-hydroxy groups acts significantly before RDA cleavage affording an ion at m/z 404.

First assessment of the Caulerpa racemosa (Caulerpales, Chlorophyta) invasion along the French Mediterranean coast.

The introduced green alga Caulerpa racemosa var. cylindracea has been rapidly spreading in the Mediterranean Sea since 1990. It was first observed in France in 1997 (Marseilles).

Restricted expression of a median Hox gene in the central nervous system of chaetognaths.

Hox genes encode a set of evolutionarily conserved transcription factors that regulate anterior-posterior patterning. Here we report the first developmental expression of a Hox gene from Chaetognatha. These metazoans have been shown recently to be part of the protostome group of bilaterians.

Effects of 12 years' operation of a sewage treatment plant on trace metal occurrence within a Mediterranean commercial sponge (Spongia officinalis, Demospongiae).

The present field study uses Spongia officinalis for assessing trace metals occurrence in time and space within Mediterranean rocky communities. Nine sites were selected in the Marseille area for studying spatial trends in 12 metal concentrations. Long term changes in 8 metal concentrations were assessed at sites that had been sampled before and 12 years after the opening of a treatment plant.

Molecular, biochemical, and physiological approaches for understanding the ecology of denitrification.

One of the major challenges in microbial ecology for the future is to establish links between structural and functional biodiversity. This is particularly difficult when one is interested in a phylogenetically diversified function such as denitrification. The data banks are very rich in functional gene sequences (nirS in this study), but most of them were obtained from not yet cultivated bacteria, and thus must be supplemented by sequences of organisms from the environment for which we could associate a taxonomic position and physiological characteristics.

Characterization of isomeric allylic diols resulting from chlorophyll phytyl side-chain photo- and autoxidation by electron ionization gas chromatography/mass spectrometry.

The electron ionization (EI) mass spectral fragmentation of the trimethylsilyl derivatives of 3-methylidene-7,11,15-trimethylhexadecane-1,2-diol, Z- and E-3,7,11,15-tetramethylhexadec-3-ene-1,2-diols and Z- and E-3,7,11,15-tetramethylhexadec-2-ene-1,4-diols resulting from chlorophyll phytyl side-chain photo- and autoxidation was investigated. Different pathways (substantiated by deuterium labelling) were proposed in order to explain the main fragmentation observed. Then, some sufficiently specific fragment ions were selected and used to characterize these compounds in natural environmental samples.

Visible light-induced oxidation of unsaturated components of cutins: a significant process during the senescence of higher plants.

9-Hydroperoxy-18-hydroxyoctadec-10(trans)-enoic and 10-hydroperoxy-18-hydroxyoctadec-8(trans)-enoic acids deriving from type II (i.e. involving 1O2) photooxidation of 18-hydroxyoleic acid were detected after visible light-induced senescence experiments carried out with Petroselinum sativum and subsequent cutin depolymerisation.

Regiospecific oxygenation of alkenones in the benthic haptophyte Chrysotila lamellosa Anand HAP 17.

Two groups of previously unidentified C37-C39 epoxyalkenones and alkenediones were detected in late stationary phase cultures of the haptophyte microalga Chrysotila lamellosa. The formation of these compounds is attributed to the involvement of enzymatic processes acting specifically on the C-21 or C-22 allylic carbon and the omega15 double bond of methyl and ethyl alkenones respectively. Thus, the epoxyalkenones appear to be derivatives of alkenones where the omega15 double bond is oxidized to the epoxide.

C(25) highly branched isoprenoid alkenes from the marine benthic diatom Pleurosigma strigosum.

The hydrocarbon composition of the marine diatom Pleurosigma strigosum isolated from coastal Mediterranean sediments is described. A suite of five C(25) highly branched isoprenoid (HBI) alkenes with 2-5 double bonds were detected together with n-C(21:4) and n-C(21:5) alkenes and squalene. The analysis by (1)H and (13)C NMR spectroscopy of two isolated HBI alkenes allowed the structural identification of a novel C(25) HBI triene (2,6,10,14-tetramethyl-7-(3-methylpent-4-enyl)-pentadeca-5E,13-diene) and the first identification in diatom cells of 2,6,10,14-tetramethyl-7-(3-methylpent-4-enyl)-pentadec-5E-ene, an HBI previously detected in marine sediments and particulate matter.

Redescription of Pleorchis polyorchis (Stossich, 1889) (Digenea: Acanthocolpidae), a rare and poorly known parasite of the intestine of Sciaena umbra l. (Perciformes: Sciaenidae) from the western Mediterranean Sea.

Pleorchis polyorchis (Stossich, 1889), the type-species of the genus, is described on the basis of new material from Sciaena umbra from off Corsica, France. This is only the second description of this species. The results of this study indicate that there are apparent errors in the original description in relation to the number of testes, the anterior limit of the vitellarium, the extent of the post-testicular field and the shape of the intestinal caeca, and that the type-species is closer to its congeners than previously believed.

Trimethylsilyl transfer during electron ionization mass spectral fragmentation of some omega-hydroxycarboxylic and omega-dicarboxylic acid trimethylsilyl derivatives and the effect of chain length.

The electron ionization (EI) mass spectral fragmentation of omega-hydroxycarboxylic and omega-dicarboxylic acid trimethylsilyl derivatives was investigated. The mass spectra of these compounds exhibited fragment ions resulting from classical fragmentation of the trimethylsilyl ether and ester groups, and others resulting from the interactions between the two functionalities (m/z 147, 204, 217, [M-31](+) and [M-105](+) in the case of omega-hydroxycarboxylic acid derivatives and m/z 147, 204, 217 and [M-131](+) in the case of omega-dicarboxylic acid derivatives). Several fragmentation pathways were proposed to explain the formation of these different fragment ions.

Identification of chaetognaths as protostomes is supported by the analysis of their mitochondrial genome.

Determining the phylogenetic position of enigmatic phyla such as Chaetognatha is a longstanding challenge for biologists. Chaetognaths (or arrow worms) are small, bilaterally symmetrical metazoans. In the past decades, their relationships within the metazoans have been strongly debated because of embryological and morphological features shared with the two main branches of Bilateria: the deuterostomes and protostomes.

Molecular phylogeny of Demospongiae: implications for classification and scenarios of character evolution.

An analysis of the phylogenetic relationships of the 13 orders of Demospongiae, based on 18S and C1, D1 and C2 domains of 28S rRNA (for, respectively, 26 and 32 taxa) has been performed. The class Demospongiae as traditionally defined is not found to be monophyletic. Instead, a clade comprising all demosponges except Homoscleromorpha is well-supported, and we define phylogenetically the name Demospongiae in this more restricted sense to preclude the possibility of drastic alterations of the meaning of Demospongiae in the future, depending on the position of Homoscleromorpha.

Autosomal differences between males and females in hybrid zones: a first report from Barbus barbus and Barbus meridionalis (Cyprinidae).

Narrow hybrid zones are generally subjected to the action of two forces: dispersal, which tends to homogenise the hybridising taxa, and selection against hybrids, which, in contrast, produces steep clines of introgression for diagnostic markers. Although differences between sexes in dispersal abilities or in susceptibility to hybrid counterselection are common in hybrid zones, autosomal genetic differences between males and females have never been reported to our knowledge. Barbus barbus and Barbus meridionalis (Cyprinidae) form a hybrid zone along the Lergue river.

Electron ionization mass spectral fragmentation of derivatized 4,5- and 5,6-epoxysterols.

The electron ionization (EI) mass spectral fragmentation of derivatized 4,5- and 5,6-epoxysterols was investigated. Interesting fragmentation processes involving a transannular cleavage of the epoxide ring after transfer of the trimethylsilyl group are significant in the case of 4,5-epoxysterol trimethylsilyl ethers (affording abundant fragment ions at m/z 403 and 404). Different pathways, which have been substantiated by deuterium labelling, are proposed in order to explain the formation of these ions.