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This paper has identified, for the first time in a member of the Rhodophyta, a vacuolar organelle containing enzymes that are involved in the mevalonate pathway-an important step in red algal isoprenoid biosynthesis. These organelles were named mevalonosomes (Mev) and were found in the cortical cells (CC) of Plocamium brasiliense, a marine macroalgae that synthesizes several halogenated monoterpenes. P. brasiliense specimens were submitted to a cytochemical analysis of the activity of the 3-hydroxy-3-methylglutaryl-CoA synthase (HMGS). Using transmission electron microscopy (TEM), we confirmed the presence of HMGS activity within the Mev. Because HMGS is necessary for the biosynthesis of halogenated monoterpenes, we isolated a hexanic fraction (HF) rich in halogenated monoterpenes from P. brasiliense that contained a pentachlorinated monoterpene as a major metabolite. Because terpenes are often related to chemical defense, the antifouling (AF) activity of pentachlorinated monoterpene was tested. We found that the settlement of the mussel Perna perna was reduced by HF treatment (2.25 times less than control; 40% and 90% of fouled surface, respectively; P = 0.001; F9,9 = 1.13). The HF (at 10 µg · mL(-1) ) also inhibited three species of fouling microalgae (Chlorarachnion reptans, Cylindrotheca cloisterium, and Exanthemachrysis gayraliae), while at a higher concentration (50 µg · mL(-1) ), it inhibited the bacteria Halomonas marina, Polaribacter irgensii, Pseudoalteromonas elyakovii, Shewanella putrefaciens, and Vibrio aestuarianus. The AF activity of P. brasiliense halogenated monoterpenes and the localization of HMGS activity inside Mev suggest that this cellular structure found in CC may play a role in thallus protection against biofouling.
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Group B Streptococcus (GBS) is the leading cause of neonatal pneumonia, septicemia, and meningitis. We have previously shown that in adult mice GBS glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is an extracellular virulence factor that induces production of the immunosuppressive cytokine interleukin-10 (IL-10) by the host early upon bacterial infection. Here, we investigate whether immunity to neonatal GBS infection could be achieved through maternal vaccination against bacterial GAPDH. Female BALB/c mice were immunized with rGAPDH and the progeny was infected with a lethal inoculum of GBS strains. Neonatal mice born from mothers immunized with rGAPDH were protected against infection with GBS strains, including the ST-17 highly virulent clone. A similar protective effect was observed in newborns passively immunized with anti-rGAPDH IgG antibodies, or F(ab')(2) fragments, indicating that protection achieved with rGAPDH vaccination is independent of opsonophagocytic killing of bacteria. Protection against lethal GBS infection through rGAPDH maternal vaccination was due to neutralization of IL-10 production soon after infection. Consequently, IL-10 deficient (IL-10(-/-)) mice pups were as resistant to GBS infection as pups born from vaccinated mothers. We observed that protection was correlated with increased neutrophil trafficking to infected organs. Thus, anti-rGAPDH or anti-IL-10R treatment of mice pups before GBS infection resulted in increased neutrophil numbers and lower bacterial load in infected organs, as compared to newborn mice treated with the respective control antibodies. We showed that mothers immunized with rGAPDH produce neutralizing antibodies that are sufficient to decrease IL-10 production and induce neutrophil recruitment into infected tissues in newborn mice. These results uncover a novel mechanism for GBS virulence in a neonatal host that could be neutralized by vaccination or immunotherapy. As GBS GAPDH is a structurally conserved enzyme that is metabolically essential for bacterial growth in media containing glucose as the sole carbon source (i.e., the blood), this protein constitutes a powerful candidate for the development of a human vaccine against this pathogen.
Assuntos
Gliceraldeído-3-Fosfato Desidrogenases/imunologia , Imunidade Materno-Adquirida/imunologia , Interleucina-10/antagonistas & inibidores , Infiltração de Neutrófilos/imunologia , Infecções Estreptocócicas/prevenção & controle , Streptococcus agalactiae/imunologia , Streptococcus agalactiae/patogenicidade , Animais , Animais Recém-Nascidos , Feminino , Imunização Passiva , Interleucina-10/deficiência , Interleucina-10/imunologia , Camundongos , Camundongos Endogâmicos BALB C , VacinaçãoRESUMO
Total lipids from the Brazilian brown seaweed Sargassum vulgare were extracted with chloroform/methanol 2:1 and 1:2 (v/v) at room temperature. After performing Folch partition of the crude lipid extract, the lipids recovered from the Folch lower layer were fractionated on a silica gel column eluted with chloroform, acetone and methanol. The fraction eluted with methanol, presented a strong orcinol-positive band characteristic of the presence of sulfatides when examined by TLC. This fraction was then purified by two successive silica gel column chromatography giving rise to fractions F4I86 and F4II90 that exhibited strong activity against herpes simplex virus type 1 and 2. The chemical structures present in both fractions were elucidated by ESI-MS and ¹H/¹³C NMR analysis HSQC fingerprints based on their tandem-MS behavior as Sulfoquinovosyldiacylglycerols (SQDGs). The main SQDG present in both fractions and responsible for the anti-herpes activity observed was identified as 1,2-di-O-palmitoyl-3-O-(6-sulfo-α-D-quinovopyranosyl)-glycerol.
Assuntos
Antivirais/química , Glicolipídeos/química , Glicolipídeos/farmacologia , Sargassum/química , Alga Marinha/química , Animais , Antivirais/farmacologia , Brasil , Linhagem Celular , Chlorocebus aethiops , Herpesvirus Humano 1/efeitos dos fármacos , Herpesvirus Humano 2/efeitos dos fármacos , Lipídeos/química , Lipídeos/farmacologia , Células VeroRESUMO
To predict the risk associated with future introductions, ecologists seek to identify traits that determine the invasiveness of species. Among numerous designated characteristics, tolerance towards environmental stress is one of the most favored. However, there is little empirical support for the assumption that non-native species generally cope better with temporarily unfavorable conditions than native species. To test this concept, we ran five pairwise comparisons between native and non-native marine invertebrates at temperate, subtropical, and tropical sites. We included (natives named first) six bivalves: Brachidontes exustus and Perna viridis, P. perna and Isognomon bicolor, Saccostrea glomerata and Crassostrea gigas, two ascidians: Diplosoma listerianum and Didemnum vexillum as well as two crustaceans: Gammarus zaddachi and G. tigrinus. We simulated acute fluctuations in salinity, oxygen concentration, and temperature, while we measured respiration and survival rates. Under stressful conditions, non-native species consistently showed less pronounced deviations from their normal respiratory performance than their native counterparts. We suggest that this indicates that they have a wider tolerance range. Furthermore, they also revealed higher survival rates under stress. Thus, stress tolerance seems to be a property of successful invaders and could therefore be a useful criterion for screening profiles and risk assessment protocols.
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Bivalves/fisiologia , Crustáceos/fisiologia , Espécies Introduzidas , Estresse Fisiológico , Urocordados/fisiologia , Aclimatação , Animais , Bivalves/classificação , Crustáceos/classificação , Ecossistema , Consumo de Oxigênio , Dinâmica Populacional , Salinidade , Temperatura , Urocordados/classificaçãoRESUMO
Surface colonization by invertebrates can be stimulated or inhibited by cues produced by biofilms, conspecifics or other macroorganisms. To study the effects of living substrata on the attachment of the brown mussel, Perna perna, two different approaches were employed: (1) mussels were distributed in sets of Petri dishes consisting of one sterile set (controls), three sets in which marine biofilms were allowed to develop in aquaria for 1, 7 or 15 days and another set that had been immersed in a natural marine environment for 1-day. There was no significant effect of biofilms on attachment, suggesting that neither age nor the source of the biofilm influenced attachment. (2) Mussels were suspended over PVC panels (controls) and over panels on which Balanus trigonus (Crustacea), Schizoporella errata (Bryozoa), Symplegma rubra or Didemnum speciosum (Ascidiacea) were present. Attachment was significantly higher on the controls and on B. trigonus than on colonial taxa such as S. rubra, S. errata and D. speciosum, probably due to antifouling defenses of these species. The results show that the composition of the biological substratum is an important factor affecting mussel behavior.
Assuntos
Bivalves/fisiologia , Adesividade , Animais , Biofilmes , Especificidade por Substrato , Propriedades de SuperfícieRESUMO
Phlorotannins are primary and/or secondary metabolites found exclusively in brown seaweeds, but their geographic distribution and abundance dynamic are not very well understood. In this study we evaluated the phlorotannin concentrations among and within-species of brown seaweeds in a broad latitudinal context (range of 21°) along the Brazilian coast (Southwestern Atlantic), using the Folin-Ciocalteau colorimetric method. In almost all species (16 out of 17) very low phlorotannin concentrations were found (<2.0%, dry weight for the species), confirming reports of the typical amounts of these chemicals in tropical brown seaweeds, but with significantly distinct values among seven different and probably highly structured populations. In all 17 seaweed species (but a total of 25 populations) analyzed there were significant differences on the amount of phlorotannins in different individuals (t-test, p < 0.01), with coefficients of variation (CV) ranging from 5.2% to 65.3%. The CV, but not the total amount of phlorotannins, was significantly correlated with latitude, and higher values of both these variables were found in brown seaweeds collected at higher latitudes. These results suggest that brown seaweeds from higher latitudes can produce phlorotannins in a wider range of amounts and probably as response to environmental variables or stimuli, compared to low latitude algae.
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Plastic pollution is a pervasive problem to marine life. This study aimed (1) to investigate levels of microplastic in wild and farmed mussels (Perna perna), and (2) to assess the effectiveness of depuration in reducing microplastics. Wild and farmed mussels were sampled from Guanabara Bay (Southwestern Atlantic). Four treatments were compared (Nâ¯=â¯10 mussels/treatment): wild non-depurated mussels, wild depurated mussels, farmed non-depurated mussels, and farmed depurated mussels. Up to 31.2⯱â¯17.8 microplastics/mussel (≥0.45⯵m) were detected (means⯱â¯SD), and microplastics were present in all 40 individuals analyzed. Nylon fibers were more abundant than polymethyl methacrylate (PMMA) fragments. Blue, transparent, and red nylon fibers were more abundant in both wild and farmed mussels. Although 93â¯h-depuration significantly reduced microplastics (ANOVA, pâ¯=â¯0.02) in both wild (46.79%) and farmed mussels (28.95%), differences between farmed and wild mussels were not significant (pâ¯>â¯0.05). Depuration was more effective in removing blue fibers. Our results highlight the importance of depuration in reducing microplastic pollution in seafood.
Assuntos
Monitoramento Ambiental/métodos , Contaminação de Alimentos/análise , Perna (Organismo)/crescimento & desenvolvimento , Plásticos/análise , Alimentos Marinhos/análise , Poluentes Químicos da Água/análise , Animais , Animais Selvagens , Aquicultura , Perna (Organismo)/químicaRESUMO
Marine invertebrates settle, attach, and/or metamorphose in response to signals from several sources, including seaweeds. In response to the aquaculture challenge of producing constant numbers of juveniles from cultured species, natural inducers have been screened for their ability to improve those processes. However, few chemical inducers of attachment of invertebrates have been identified, and even less of these were secondary metabolites. The goal of this work was to isolate the natural products responsible for induction activity using bioassay-guided fractionation of the organic extract of the brown seaweed Stypopodium zonale and the attachment of juveniles of the common brown mussel, Perna perna, as a model. The meroditerpene epitaondiol, identified by comparison of spectral data with the literature, promoted as much as 4.7 times more mussel attachment compared to controls at the natural concentration found in this alga (0.041% of the crude extract or 0.012% of algal dry weight). This is the first report showing that a seaweed produces terpenoid compounds as cues for invertebrate attachment, and future studies evaluating this action on settlement of mussels in the field are expected to improve aquaculture technology by increasing mussel spat production.
Assuntos
Perna (Organismo)/efeitos dos fármacos , Perna (Organismo)/metabolismo , Phaeophyceae/química , Alga Marinha/química , Terpenos/farmacologia , Animais , Aquicultura , Bioensaio , Produtos Biológicos/química , Produtos Biológicos/isolamento & purificação , Produtos Biológicos/farmacologia , Análise Espectral , Terpenos/química , Terpenos/isolamento & purificaçãoRESUMO
Epibiosis or fouling on living organisms can have direct and indirect detrimental effects, in particular on photosynthetic organisms such as seaweeds. It thus seems reasonable to hypothesize that macroalgae have been selected for the presence or induction of antifouling (AF) defences. The red seaweed Cryptonemia seminervis is usually found in nature with an elevated cover of epibionts. To assess the effect of epibiosis on the susceptibility of this seaweed to herbivory and fouling, the abundance of fouling was evaluated and compared to herbivore consumption (by amphipods and sea urchins) of fouled (bryozoan and sponge) and non-fouled C. seminervis. Attachment of the mussel Perna perna to surfaces treated with extracts from seaweeds with and without epibionts was also assessed. Epibiosis corresponded to ca. 51% of the blade surface of C. seminervis, sometimes covering as much as 90% and up to 51% of the thallus weight, encompassing mainly the bryozoan Membranipora membranacea and an unidentified sponge. Algae colonized by M. membranacea were preferred compared to algae devoid of epibionts, a 'shared doom' effect, either by the amphipod Elasmopus brasiliensis or by the urchin Lytechinus variegatus (p < 0.01). Sponge epibiosis also increased consumption by both herbivores (p < 0.001), suggesting that epibionts may act as lures to herbivores, attracting consumers that otherwise would not feed significantly on the seaweed. Foods containing extracts from fouled C. seminervis were preferred by urchins over the alga devoid of epibionts. However, extracts from fouled alga inhibited mussel attachment when compared to epibiont-free alga. Differences might be a direct detrimental effect of the presence of epibionts. On the other hand, epibiosis may induce the production of AF defences in C. seminervis.
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Comportamento Alimentar , Rodófitas/crescimento & desenvolvimento , Simbiose , Anfípodes/metabolismo , Animais , Briozoários/crescimento & desenvolvimento , Lytechinus/metabolismo , Perna (Organismo)/crescimento & desenvolvimento , Porphyra/crescimento & desenvolvimentoRESUMO
Calcified sclerites are common in many benthic marine invertebrates, and despite their widespread occurrence, little is known about their ecological roles. Previous studies suggested that the sclerite composition of coral colonies may be altered in response to environmental cues such as predation and water motion. Furthermore, larger sclerites are thought to be more effective than small ones in deterring predators, while small sclerites may provide greater stiffness and resistance to deformation. The present study compared the length of the sclerites of the sea pansy Renilla muelleri from three depths in Guanabara Bay in southeastern Brazil. Our results show that sclerites are larger in deep-water specimens than in those from shallow water. Field assays were conducted in which sclerites from sea pansies at three depths were incorporated into artificial foods and offered to a natural assemblage of fish. These assays demonstrate that sclerites from R. muelleri from all three depths significantly reduced consumption by generalist carnivorous fishes. We conclude that R. muelleri uses skeletal elements not only to give the body its form but also as a defense against biotic threats.
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Adaptação Fisiológica , Ecossistema , Renilla/anatomia & histologia , Animais , Oceano Atlântico , Brasil , Perciformes/fisiologia , Comportamento Predatório/fisiologia , Renilla/fisiologia , Clima TropicalRESUMO
Despite advances in understanding the ecological functions of secondary metabolites from marine organisms, there has been little focus on the influence of chemically-defended species at the community level. Several compounds have been isolated from the gorgonian octocoral Phyllogorgia dilatata, a conspicuous species that forms dense canopies on rocky reefs of northern Rio de Janeiro State, Brazil. Manipulative experiments were performed to study: (1) the effects of live colonies of P. dilatata (physical presence and chemistry) on recruitment of sympatric benthic organisms; (2) the allelopathic effects of its chemicals on competitors; and (3) chemotactic responses of the non-indigenous brittle star, Ophiothela mirabilis. Early establishment of benthic species was influenced on substrates around live P. dilatata colonies and some effects could be attributed to the gorgonian's secondary metabolites.In addition, the gorgonian chemicals also exerted an allelopathic effect on the sympatric zoanthid Palythoa caribaeorum, and positive chemotaxis upon O. mirabilis. These results indicate multiple ecological roles of a chemically-defended gorgonian on settlement, sympatric competitors, and non-indigenous species.
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Microplastics, which are accumulating in marine sediments, are assumed to pose a risk for deposit feeding invertebrates. We tested whether the fiddler crab Uca rapax ingests and retains microplastics in its body. Furthermore, we investigated whether retention rates depend on (a) the quality of the marine environment in which the plastics were pre-weathered and on (b) their abundance. For this, polystyrene pellets were submersed at a polluted and a pristine site near Niterói, Brazil, for 2 weeks. Then specimens of U. rapax were, in laboratory experiments, exposed to fragments (180-250 µm) derived from these pellets for 2 months. After this period, microplastics were observed in the gills, stomach and hepatopancreas of the animals. However, fragment retention was not influenced by the two factors that we manipulated. The presence of microplastics in different organs of the crab supports the assumption that these particles have the potential to harm marine invertebrates.
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Braquiúros/metabolismo , Plásticos/metabolismo , Frutos do Mar , Poluentes Químicos da Água/metabolismo , Animais , Brasil , Meio Ambiente , Sedimentos Geológicos , Brânquias , Hepatopâncreas , Masculino , Poliestirenos/metabolismo , Estômago , Distribuição TecidualRESUMO
Marine macroalgae, or seaweeds, are a formidable source of natural compounds with diverse biological activities. In the last five decades it has been estimated that more than 3000 natural compounds were discovered from these organisms. The great majority of the published works have focused on terpenoids. In comparison, glycolipids are a neglected class of macroalgal secondary metabolites therefore remaining as a largely unknown reservoir of molecular diversity. Nevertheless, the interest regarding these compounds has been growing fast in the last decades as activities of ecological or pharmaceutical interest have been highlighted. This paper will review recent work regarding isolation and structural characterization of glycolipids from seaweeds and their prospective biological activities.
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Fatores Biológicos/química , Biotecnologia , Glicolipídeos/química , Alga Marinha/química , Animais , Fatores Biológicos/isolamento & purificação , Fatores Biológicos/farmacologia , Glicolipídeos/isolamento & purificação , Glicolipídeos/farmacologia , Humanos , Alga Marinha/classificaçãoRESUMO
Species richness is the most commonly used but controversial biodiversity metric in studies on aspects of community stability such as structural composition or productivity. The apparent ambiguity of theoretical and experimental findings may in part be due to experimental shortcomings and/or heterogeneity of scales and methods in earlier studies. This has led to an urgent call for improved and more realistic experiments. In a series of experiments replicated at a global scale we translocated several hundred marine hard bottom communities to new environments simulating a rapid but moderate environmental change. Subsequently, we measured their rate of compositional change (re-structuring) which in the great majority of cases represented a compositional convergence towards local communities. Re-structuring is driven by mortality of community components (original species) and establishment of new species in the changed environmental context. The rate of this re-structuring was then related to various system properties. We show that availability of free substratum relates negatively while taxon richness relates positively to structural persistence (i.e., no or slow re-structuring). Thus, when faced with environmental change, taxon-rich communities retain their original composition longer than taxon-poor communities. The effect of taxon richness, however, interacts with another aspect of diversity, functional richness. Indeed, taxon richness relates positively to persistence in functionally depauperate communities, but not in functionally diverse communities. The interaction between taxonomic and functional diversity with regard to the behaviour of communities exposed to environmental stress may help understand some of the seemingly contrasting findings of past research.
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Biodiversidade , Internacionalidade , Invertebrados/crescimento & desenvolvimento , Água do Mar , Animais , Dinâmica Populacional , Especificidade da EspécieRESUMO
Natural within-thallus concentrations of elatol produced by Laurencia obtusa (Huds.) J. V. Lamour. inhibit herbivory and prevent fouling. However, elatol occurs in larger amounts within the thallus compared with the quantities from the surface of this alga. We evaluated whether the surface elatol concentrations inhibit both herbivory and fouling and whether the content of corps en cerise can be transferred to the external cell walls. Surface elatol concentrations did not inhibit herbivory by sea urchins, settlement of barnacle larvae, or mussel attachment. Evidence of a connection between the corps en cerise, where elatol is probably stored, and the cell wall of L. obtusa was based on channel-like membranous connections that transport vesicles from the corps to the cell wall region. Therefore, L. obtusa presents a specific process of chemical transport between the cell storage structures and the plant surface. We hypothesized that if high amounts of elatol are capable of inhibiting herbivory and fouling, if the tested organisms are ecologically relevant, and if elatol really occurs on the surface of L. obtusa and this seaweed can transport this compound to its surface, the low natural concentration of defensive chemicals on the surface of L. obtusa is probably not absolute but may be variable according to environmental conditions. We also hypothesized that herbivory and fouling would not exert the same selective force for the production of defensive chemicals on L. obtusa's surface since the low concentrations of elatol were inefficient to inhibit either processes or distinguish selective pressures.
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Current antifouling technologies rely on metal-based paints, but due to their toxicity, an expected worldwide ban of organotin-containing paints is now prompting the quest for safe and effective alternatives. One of these is antifouling coatings whose active components are naturally occurring compounds in marine organisms. A number of laboratory bioassays has been designed to search for antifouling compounds. However, there is no evidence to date that these assays provide results reproducible through ecologically realistic field experiments. Natural concentrations of the extracts from the Brazilian seaweeds Laurencia obtusa and Stypopodium zonale were tested in the laboratory through the 'mussel test' and in the field through the 'phytagel method' in order to compare the efficiency of these methods in assessing antifouling activity. L. obtusa extract significantly inhibited fouling in both the laboratory and field assays, while S. zonale stimulated fouling in both assays. Major compounds from the extracts were identified. The findings suggest that the 'mussel test' is a reliable time and cost-saving screening method for antifouling substances, although field assays are more sensitive for detection of their activity spectrum.