119 research outputs found
Preliminary observations of caulerpin accumulation from the invasive Caulerpa cylindracea in native Mediterranean fish species
Recent studies have shown that the Mediterranean white sea bream Diplodus sargus includes the invasive green alga Caulerpa cylindracea in its diet, with consequent metabolic and enzymatic alterations. As a result of this novel alimentary habit, the bioactive algal red pigment caulerpin has been detected in its tissues. However, this may not be an isolated case: other fish species have also been reported to feed on C. cylindracea, although the possible accumulation of caulerpin in their tissues has not yet been investigated. In this report, we analysed stomach contents and caulerpin levels in the native sparid species Spondyliosoma cantharus, Sarpa salpa, and Diplodus vulgaris, and in the scarid Sparisoma cretense, along with the Lessepsian siganid Siganus luridus. C. cylindracea was found in the stomachs of all but one fish species, the exception being S. cretense, in which prey items could not be determined due to the high degree of digestion. Chemical analysis of fish tissues revealed that only S. cantharus and S. salpa accumulated caulerpin, while no traces of the compound were detected in the other species. Despite intense research efforts on natural products obtained from C. cylindracea, a complete picture of the impacts caused by fish including this alga in their diet has not been elucidated. The identification of caulerpin in other Mediterranean native fish suggests a need for further research in order to assess the possible transfer of such molecules to humans through seafood consumption
Anti‑predatory chemical defences in Antarctic benthic fauna
Antarctic benthic communities are largely structured by predation, which leads to the development of mechanisms of repellence. Among those mechanisms, chemical defences are quite extensive, yet poorly understood. To increase knowledge about the role of chemical defences in the Southern Ocean ecosystems, we assessed the incidence of feeding repellents in sessile and vagile invertebrates from nine phyla: Porifera, Cnidaria, Nemertea, Annelida, Mollusca, Bryozoa, Echinodermata, Hemichordata, and Tunicata (Ascidiacea). Samples were collected at depths of 120–789 m in the eastern Weddell Sea and Bouvet Island, and at depths ranging 0–100 m in the South Shetland Islands. When possible, specimens were dissected to study anatomical allocation of repellents. The common, eurybathic sea star Odontaster validus was chosen to perform feeding repellence bioassays, using diethyl ether (lipophilic) and butanol (hydrophilic) extracts from these samples. Among the 75 species tested, 52 % were studied for the first time for anti-predatory properties. Results provide further evidence of the prevalence of defensive metabolites in Antarctic organisms, with 47 % of the species exhibiting significant repellence within their lipophilic extracts. They also suggest a wider use of nonpolar defensive chemicals. Sessile taxa displayed highest repellence activities, with ascidians, cnidarians, and sponges being the most chemically protected. Overall, the present study indicates that natural products by mediating trophic interactions between prey and their potential predators play an important role in structuring Antarctic benthic ecosystems.Versión del editor2,011
Molecular Evidence of the Toxic Effects of Diatom Diets on Gene Expression Patterns in Copepods
Diatoms are dominant photosynthetic organisms in the world's oceans and are considered essential in the transfer of energy through marine food chains. However, these unicellular plants at times produce secondary metabolites such as polyunsaturated aldehydes and other products deriving from the oxidation of fatty acids that are collectively termed oxylipins. These cytotoxic compounds are responsible for growth inhibition and teratogenic activity, potentially sabotaging future generations of grazers by inducing poor recruitment in marine organisms such as crustacean copepods.Here we show that two days of feeding on a strong oxylipin-producing diatom (Skeletonema marinoi) is sufficient to inhibit a series of genes involved in aldehyde detoxification, apoptosis, cytoskeleton structure and stress response in the copepod Calanus helgolandicus. Of the 18 transcripts analyzed by RT-qPCR at least 50% were strongly down-regulated (aldehyde dehydrogenase 9, 8 and 6, cellular apoptosis susceptibility and inhibitor of apoptosis IAP proteins, heat shock protein 40, alpha- and beta-tubulins) compared to animals fed on a weak oxylipin-producing diet (Chaetoceros socialis) which showed no changes in gene expression profiles.Our results provide molecular evidence of the toxic effects of strong oxylipin-producing diatoms on grazers, showing that primary defense systems that should be activated to protect copepods against toxic algae can be inhibited. On the other hand other classical detoxification genes (glutathione S-transferase, superoxide dismutase, catalase, cytochrome P450) were not affected possibly due to short exposure times. Given the importance of diatom blooms in nutrient-rich aquatic environments these results offer a plausible explanation for the inefficient use of a potentially valuable food resource, the spring diatom bloom, by some copepod species
Biosynthetic Pathways in Marine Invertebrates as Untapped Resource of Biotechnological Applications
Marineinvertebrates have been emerging as a very promising source of both natural products and enzymatic activities. In this contribution, we have tried to provide a general overview of the present knowledge of the enzymatic transformations and biosynthetic pathways in marine molluscs, suggesting that marine enzymes have great, yet unexplored diversity in both mechanism and structure. We hope that the extraordinary mechanism and catalytic reactivity discussed throughout the manuscript may serve as an inspiration in searching for novel biocatalytic properties
One Metabolite, Two Pathways: Convergence of Polypropionate Biosynthesis in Fungi and Marine Molluscs
Structural similarity or even the identity of polyketide compounds does not necessarily imply unique biosynthesis. Feeding experiments with a 13C
labeled precursor establish that the C3 units in 7-methyl-cyercene-1 (1) are derived from intact propionate in the marine mollusc Ercolania funerea.
The same compound in the terrestrial fungus Leptosphaeria maculans/Phoma lingam is synthesized by an acetate/SAM pathway thus proving for
the first time metabolic convergence of polyketide biosynthesis in eukaryotes. Traditional 1H13C NMR correlation spectroscopy has been
successfully applied to estimate 13C incorporation in biosynthetic experiments
A chemical investigation of the Antarctic sponge Lyssodendoryx flabellata
From the Antarctic sponge Lyssodendoryx flabellata, a new polycyclic
compound, which we named flabellone, related to the oestrogenic hormone
oestrone, has been elucidated by spectrometric and spectroscopic means.
Along with flabellone, a glycosphingolipid (GSL) mixture featuring an
unusual -fucofuranosyl-3--glucopyranoside unit structurally identical to
the previously reported terpioside has been isolated and identified. The
mixture of GSL homologues exhibited inhibitory effects in mixed lymphocyte
reactions on human cells
UPLC-MS/MS method for analysis of sphingosine 1-phosphate in biological samples
A simple and sensitive liquid chromatography–tandem mass spectrometry (negative ion-electrospray
ionization) methodology to determine sphingosine 1-phosphate (S1P) and sphinganine 1-phosphate
(DH-S1P) in biological samples is described. The method has been validated over the linearity range
of 2–100 ng/ml (r > 0.999) using synthetic C17-sphingosine 1-phosphate (C17-S1P) as an internal standard.
In multiple reaction monitoring analysis (378.2 > 79.2), the lower limit of quantification for S1P
was 5.0 ng/ml but the detection limit for the bioactive lipid was below 5 pg (12 fmol). Chromatographic
separation was achieved on a UPLC BEH Hilic column with a binary mobile phase consisting of 30mM
ammonium acetate (pH 4.0) and acetonitrile/MeOH/30mM ammonium acetate buffer (pH 4.0). The
methodology detected 176.7±54.0 ng/ml of S1P and 81.2±23.3 ng/ml of DH-S1P in human plasma, as
well as 201.0±72.0 ng/ml of S1P and 96.5±20.1 ng/ml of DH-S1P in mice plasma
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