ECOLOGIA QUÍMICA MARINHA: ORIGEM, EVOLUÇÃO E PERSPECTIVAS NO BRASIL

MARINE CHEMICAL ECOLOGY: ORIGIN, DEVELOPMENT AND PERSPECTIVES IN BRAZIL. This report reviewed the information about development of marine chemical ecology in Brazil since its origin until May 2011 through analysis of scientific publications and professional formation at different levels. Basic macroalgal studies were predominant, mainly those studies focused on the effect of crude extracts and some pure compounds evaluated as chemical defenses against consumers. The macroalgal approaches also constitute important contributions related to structure and function, intra-population variation, storage and transport of chemical defenses. The number of invertebrate chemical ecology studies although small, verified the presence and activity of secondary metabolites, chemical cues for hosts to associated and chemical defenses in exotic species. Brazilian marine chemical ecology has evolved in accordance to this science in the world, as mostly papers were published in scientific journals of broad accessing. Despite the number of professionals has increased recently, the development of national marine chemical ecology remains slow due to reduced number of PhD formed and that could be head and spread new centers for research and professional formation. Considering the contribution of environmental and genetic factors for the production of chemical cues, the expansion of researches and professional formation, essentially PhDs, must be the basis to understand the pattern of abundance and action of secondary metabolites and their roles in marine community structure. Keywords:  Marine chemical ecology; chemical interactions; chemical defenses; alellopathy.ECOLOGÍA QUÍMICA MARINA: ORIGEN, EVOLUCIÓN Y PERSPECTIVAS EN BRASIL. El presente informe analizó el desarrollo de la ecología química marina en Brasil desde su origen hasta septiembre de 2010, a través del análisis de las publicaciones científicas y de la formación profesional en diferentes niveles. Los estudios básicos con macroalgas fueron predominantes, principalmente aquéllos enfocados en el efecto de extractos y algunas sustancias puras evaluadas como defensas químicas contra consumidores. Los estudios de macroalgas también constituyen importantes contribuciones, relacionadas con la estructura y función, la variación intra-poblacional, el almacenamiento y el transporte de defensas químicas. Sin embargo, el número de estudios de ecología química de invertebrados fue reducido, éstos verificaron la presencia y actividad de metabolitos secundarios, la señalización química para hospederos y defensas químicas en especies exóticas. La ecología química marina brasileña ha evolucionado en consonancia con esta ciencia en el mundo, una vez que predominan las publicaciones en revistas científicas de amplia circulación. A pesar del aumento reciente del número de profesionales en química marina, el desarrollo nacional continua siendo lento debido al número reducido de doctores formados. Considerando la contribución de factores genéticos y ambientales para la producción de señales químicas, la expansión de la investigación y formación profesional, esencialmente de doctores, debe ser la base para la comprensión de los patrones de abundancia y de acción de los metabolitos secundarios y sus funciones en la estructura de las comunidades marinas. Palabras clave: Ecología química marina; interacciones químicas; defensas químicas; alelopatía.Este relatório analisou as informações sobre o desenvolvimento da ecologia química marinha no Brasil desde sua origem até setembro de 2010 através da análise das publicações científicas e formação profissional em diferentes níveis.  Os estudos básicos de macroalgas foram predominantes, principalmente aqueles focados no efeito de extratos e algumas substâncias puras avaliadas como defesas químicas contra consumidores. As abordagens de macroalgas também constituem importantes contribuições relacionadas com a estrutura e função, a variação intra-populacional, armazenamento e transporte de defesas químicas. No entanto, o número de estudos de ecologia química de invertebrados mostrou-se reduzido, os quais verificaram a presença e a atividade de metabólitos secundários, sinalização química para hospedeiros e defesas químicas em espécies exóticas.  A ecologia química marinha brasileira tem evoluído em consonância com esta ciência no mundo, uma vez que predominam as publicações em revistas científicas de ampla circulação. Apesar do número de profissionais da química marinha ter aumentado recentemente, o desenvolvimento nacional continua a ser lento devido ao número reduzido de doutores formados. Considerando a contribuição de fatores genéticos e ambientais para a produção de sinais químicos, a expansão de pesquisas e formação profissional, essencialmente de doutores, deve ser a base para a compreensão do padrão de abundância e de ação dos metabólitos secundários e suas funções na estrutura das comunidades marinhas

Effect of Elatol, Isolated from Red Seaweed Laurencia dendroidea, on Leishmania amazonensis

In the present study, we investigated the antileishmanial activity of sesquiterpene elatol, the major constituent of the Brazilian red seaweed Laurencia dendroidea (Hudson) J.V. Lamouroux, against L. amazonensis. Elatol after 72 h of treatment, showed an IC50 of 4.0 μM and 0.45 μM for promastigote and intracellular amastigote forms of L. amazonensis, respectively. By scanning and transmission electron microscopy, parasites treated with elatol revealed notable changes compared with control cells, including: pronounced swelling of the mitochondrion; appearance of concentric membrane structures inside the organelle; destabilization of the plasma membrane; and formation of membrane structures, apparently an extension of the endoplasmic reticulum, which is suggestive of an autophagic process. A cytotoxicity assay showed that the action of the isolated compound is more specific for protozoa, and it is not toxic to macrophages. Our studies indicated that elatol is a potent antiproliferative agent against promastigote and intracellular amastigote forms, and may have important advantages for the development of new anti-leishamanial chemotherapies

Diel density variation of amphipods associated with Sargassum beds from two shores of Ubatuba, Southeastern, Brazil

Densities of mobile epifaunal assemblages associated with macrophytes are very variable during the day and the activity of visually-oriented predators is thought to have an important influence on this pattern. Here we compared densities of amphipods associated with a common brown alga, Sargassum stenophyllum (Phaeophyceae), at sites contrasting in water turbidity. We expected that diel variation of amphipods would occur in a shore with clear waters (Perequê), whereas no variation was expected in a shore with turbid waters (Lamberto). Amphipod density varied during the day at both shores, with no indication of a larger variation at Perequê. Most species showed two density peaks, one at night and the other in the afternoon. These peaks occurred close the times of high tide, suggesting that tidal rhythms could influence more amphipod densities than the activity of predators. Thus, more studies are necessary to understand factors that influence short-term variation of epifaunal assemblages

Variação ao longo do dia na densidade de anfípodos associados a bancos de Sargassum em duas praias de Ubatuba, SP, Brasil

Densities of mobile epifaunal assemblages associated with macrophytes are very variable during the day and the activity of visually-oriented predators is thought to have an important influence on this pattern. Here we compared densities of amphipods associated with a common brown alga, Sargassum stenophyllum (Phaeophyceae), at sites contrasting in water turbidity. We expected that diel variation of amphipods would occur in a shore with clear waters (Perequê), whereas no variation was expected in a shore with turbid waters (Lamberto). Amphipod density varied during the day at both shores, with no indication of a larger variation at Perequê. Most species showed two density peaks, one at night and the other in the afternoon. These peaks occurred close the times of high tide, suggesting that tidal rhythms could influence more amphipod densities than the activity of predators. Thus, more studies are necessary to understand factors that influence short-term variation of epifaunal assemblages.As densidades da epifauna móvel associada a macrófitas variam muito ao longo do dia, sendo a atividade de predadores visualmente orientados um dos principais fatores apontados para explicar este padrão. Neste estudo, comparamos as densidades de anfípodos associados a uma alga parda comum, Sargassum stenophyllum (Phaeophyceae), em praias contrastando em turbidez da água. Era esperada a ocorrência de variação ao longo do dia numa praia com águas claras (Perequê) e nenhuma variação na praia com águas turvas (Lamberto). A densidade de anfípodos variou ao longo do dia em ambas as praias, sem indicação de maior variação em Perequê. A maioria das espécies apresentou dois picos de densidade: um à noite e outro à tarde. Estes ocorreram próximos aos períodos de maré alta, sugerindo que o ritmo de maré poderia influenciar mais as densidades de anfípodos que a atividade de predadores. Assim, mais estudos são necessários para se compreender os fatores que influenciam a variação de curto prazo das comunidades epifaunais.400405Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Additional Evidence of the Trypanocidal Action of (−)-Elatol on Amastigote Forms through the Involvement of Reactive Oxygen Species

Chagas’ disease, a vector-transmitted infectious disease, is caused by the protozoa parasite Trypanosoma cruzi. Drugs that are currently available for the treatment of this disease are unsatisfactory, making the search for new chemotherapeutic agents a priority. We recently described the trypanocidal action of (−)-elatol, extracted from the macroalga Laurencia dendroidea. However, nothing has been described about the mechanism of action of this compound on amastigotes that are involved in the chronic phase of Chagas’ disease. The goal of the present study was to evaluate the effect of (−)-elatol on the formation of superoxide anions (O2•−), DNA fragmentation, and autophagy in amastigotes of T. cruzi to elucidate the possible mechanism of the trypanocidal action of (−)-elatol. Treatment of the amastigotes with (−)-elatol increased the formation of O2•− at all concentrations of (−)-elatol assayed compared with untreated parasites. Increased fluorescence was observed in parasites treated with (−)-elatol, indicating DNA fragmentation and the formation of autophagic compartments. The results suggest that the trypanocidal action of (−)-elatol might involve the induction of the autophagic and apoptotic death pathways triggered by an imbalance of the parasite’s redox metabolism

Role of ABC Proteins in Secondary Metabolism and Immune (=Defensive) Response in Seaweeds

Laurencia seaweed species synthesize a broad range of secondary metabolites, mainly terpenes (e.g., elatol), exhibiting diverse ecological roles, such as defense against fouling and herbivores. Recently, an intricate cellular machinery was described concerning terpenes biosynthetic pathways, storage inside corps en cerise (CC), and regulated exocytosis in these species. But for seaweeds in general, the proteins involved in transmembrane transport of secondary metabolites remain unknown. Assays with Rhodamine-123 and cyclosporine A (CSA) revealed the presence of ABC transporters in CC membrane of Laurencia dendroidea. In vivo incubation assays with CSA resulted in CC morphological changes, reduced intracellular elatol concentrations, and increased biofouling cover on the seaweed surface. Cultivation assays in the presence of a marine pathogenic bacteria induced the expression of ABC proteins belonging to the subfamilies ABCB, ABCD, ABCF, and ABCG. The latter subfamily is known to be associated with the transport of plant terpenes. Our results shed new light on the role of ABC proteins in key mechanisms of the defensive system in seaweeds against fouling and herbivory

Structure of Rhodolith Beds and Surrounding Habitats at the Doce River Shelf (Brazil)

The world’s largest rhodolith beds have been reported from the Brazilian continental shelf. Highly biodiverse beds are located in Southeast Brazil, but ecological aspects of these beds remain unknown. Despite their ecological importance, rhodolith beds (RBs) have recently been subjected to a severe threat, when more than 35 million cubic meters of mining residues slid down a mountainside on 5 November 2015, after a collapse of a gigantic dam upstream (the Mariana disaster), causing a huge impact on the Doce River. Our aim is to assess rhodolith beds and adjacent coralline formations on the Doce River Shelf (DRS) after the dam collapse. This paper describes the distribution, abundance, vitality, size and shape, as well as unmapped bryozoan rich sediment formations in this area, serving as baseline knowledge for environmental monitoring. Four distinct biogenic sea bottom habitats (bryozoan bottoms, rhodolith beds, carbonate concretions, and reefs) were recognized at different depth ranges with distribution indicated to be mostly related to the local sedimentary regime. Mud sediments dominated the seafloor up to 35 m depth. On the mid shelf, bryozoan bottoms were recorded from 35 to 45 m depth. Crustose coralline algae (CCA) occurring as rhodoliths and carbonate concretions extend over 1953 km2 in the mid and outer shelf. Rhodolith beds predominate in these areas, totaling 1521 km2 of sea bottom and were more abundant at depths between 45 and 65 m, occupying an extensive area south of the Doce River mouth. Northward, rhodolith beds are less abundant or absent likely due to the long-term deposition of fine sediments in this region. Carbonate concretions and reefs covered by CCA occupy sparse areas on the outer shelf (65–105 m depth). Differences in rhodolith features recorded, including coverage, density and size, may be related to the Doce River sedimentation and related factors (e.g., hydrodynamics, depth, and light). However, since there are no previous detailed studies on RBs along the DRS, we could not assess the impact of sedimentation of dam wastes on RBs’ abundance and density. In any case, these are valuable results for the further monitoring of long-term effects. Considering that the growth of these rhodoliths is relatively slow, and that they are affected by the sedimentation from the Doce River, the implementation of a management and conservation plan for this area is necessary in order to preserve this ecosystem

Molecular Mechanisms for Microbe Recognition and Defense by the Red Seaweed Laurencia dendroidea

ABSTRACT The ability to recognize and respond to the presence of microbes is an essential strategy for seaweeds to survive in the marine environment, but understanding of molecular seaweed-microbe interactions is limited. Laurencia dendroidea clones were inoculated with the marine bacterium Vibrio madracius. The seaweed RNA was sequenced, providing an unprecedentedly high coverage of the transcriptome of Laurencia, and the gene expression levels were compared between control and inoculated samples after 24, 48, and 72 h. Transcriptomic changes in L. dendroidea in the presence of V. madracius include the upregulation of genes that participate in signaling pathways described here for the first time as a response of seaweeds to microbes. Genes coding for defense-related transcription activators, reactive oxygen species metabolism, terpene biosynthesis, and energy conversion pathways were upregulated in inoculated samples of L. dendroidea, indicating an integrated defensive system in seaweeds. This report contributes significantly to the current knowledge about the molecular mechanisms involved in the highly dynamic seaweed-bacterium interactions. IMPORTANCE Marine bacteria are part of the healthy microbiota associated with seaweeds, but some species, such as Vibrio spp., are frequently associated with disease outbreaks, especially in economically valuable cultures. In this context, the ability of seaweeds to recognize microbes and, when necessary, activate defense mechanisms is essential for their survival. However, studies dedicated to understanding the molecular components of the immune response in seaweeds are rare and restricted to indirect stimulus. This work provides an unprecedentedly large-scale evaluation of the transcriptional changes involved in microbe recognition, cellular signaling, and defense in the red seaweed Laurencia dendroidea in response to the marine bacterium Vibrio madracius. By expanding knowledge about seaweed-bacterium interactions and about the integrated defensive system in seaweeds, this work offers the basis for the development of tools to increase the resistance of cultured seaweeds to bacterial infections

Trypanocidal action of (−)-elatol involves an oxidative stress triggered by Mitochondria dysfunction

Submitted by Franciele Moreira ([email protected]) on 2018-06-13T15:44:25Z No. of bitstreams: 2 Artigo - Vânia Cristina Desoti - 2012.pdf: 10300592 bytes, checksum: e08312a8af0cb537931b7e8dc2330e95 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)Approved for entry into archive by Luciana Ferreira ([email protected]) on 2018-06-14T11:39:32Z (GMT) No. of bitstreams: 2 Artigo - Vânia Cristina Desoti - 2012.pdf: 10300592 bytes, checksum: e08312a8af0cb537931b7e8dc2330e95 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)Made available in DSpace on 2018-06-14T11:39:33Z (GMT). No. of bitstreams: 2 Artigo - Vânia Cristina Desoti - 2012.pdf: 10300592 bytes, checksum: e08312a8af0cb537931b7e8dc2330e95 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2012Natural compounds have shown good potential for the discovery of new chemotherapeutics for the treatment of Chagas’ disease. Recently, our group reported the effective trypanocidal activity of (−)-elatol, extracted from the red macroalgae Laurencia dendroidea present in the Brazilian coast against Trypanosoma cruzi. However, the mechanism of action of this compound has remained unclear. There are only hypotheses concerning its action on mitochondrial function. Here, we further investigated the mechanisms of action of (−)-elatol on trypomastigotes of T. cruzi. For this, we evaluated some biochemical alterations in trypomastigotes treated with (−)-elatol. Our results show that (−)-elatol induced depolarization of the mitochondrial membrane, an increase in the formation of mitochondrial superoxide anion and loss of cell membrane and DNA integrity. Additionally, (−)-elatol induced formation of autophagic vacuoles and a decrease in cell volume. All together, these results suggest that the trypanocidal action of (−)-elatol involves multiple events and mitochondria might be the initial target organelle. Our hypothesis is that the mitochondrial dysfunction leads to an increase of ROS production through the electron transport chain, which affects cell membrane and DNA integrity leading to different types of parasite death