Yocie Yoneshigue-Valentin

Marine Biodiversity in the Atlantic and Pacific Coasts of South America: Knowledge and Gaps

The marine areas of South America (SA) include almost 30,000 km of coastline and encompass three different oceanic domains--the Caribbean, the Pacific, and the Atlantic--ranging in latitude from 12∘N to 55∘S. The 10 countries that border these coasts have different research capabilities and taxonomic traditions that affect taxonomic knowledge. This paper analyzes the status of knowledge of marine biodiversity in five subregions along the Atlantic and Pacific coasts of South America (SA): the Tropical East Pacific, the Humboldt Current,the Patagonian Shelf, the Brazilian Shelves, and the Tropical West Atlantic, and it provides a review of ecosystem threats and regional marine conservation strategies. South American marine biodiversity is least well known in the tropical subregions (with the exception of Costa Rica and Panama). Differences in total biodiversity were observed between the Atlantic and Pacific oceans at the same latitude. In the north of the continent, the Tropical East Pacific is richer in species than the Tropical West Atlantic, however, when standardized by coastal length, there is very little difference among them. In the south, the Humboldt Current system is much richer than the Patagonian Shelf. An analysis of endemism shows that 75% of the species are reported within only one of the SA regions, while about 22% of the species of SA are not reported elsewhere in the world. National and regional initiatives focusing on new exploration, especially to unknown areas and ecosystems, as well as collaboration among countries are fundamental to achieving the goal of completing inventories of species diversity and distribution.These inventories will allow accurate interpretation of the biogeography of its two oceanic coasts and latitudinal trends,and will also provide relevant information for science based policies.

Ecological roles of natural products of the Brazilian red seaweed Laurencia obtusa

Laboratory and field experiments were performed to assess the ecological roles of natural products produced by the Brazilian red seaweed Laurencia obtusa. Laboratory assays revealed that the natural concentration of the crude organic extract of L. obtusa significantly inhibited feeding by two herbivores: the crab Pachygrapsus transversus and the sea urchin Lytechinus variegatus. It was verified that this chemically defensive action was due to halogenated sesquiterpenoid elatol, found to be the major natural product of this red seaweed. In addition, it was verified that the antifouling property of the chemicals produced by L. obtusa could make this red alga less attractive for fish grazing. Direct protection against two herbivore species and indirect protection against herbivory by fouling inibition constitute evidence that the major natural product from Brazilian L. obtusa plays multiple environmental roles, thereby increasing the adaptive value of these metabolites. On the other hand, the evidence reinforces the idea that marine natural products may have different functions in the sea.

Photosynthetic light‐response curves and photoinhibition of the deep‐water laminaria abyssalis and the intertidal laminaria digitata (phaeophyceae)

Photosynthetic light‐response curves of the deep‐water Laminaria abyssalis Oliveira and of the intertidal L. digitata Lamoroux were determined and related to photoinhibition phenomena as monitored by oxygen evolution and photosystem II efficiency (FV/FM). L. abyssalis has half the pigment content, number of cells and plastids, and photosynthetic capacity per unit area compared with L. digitata. L. abyssalis showed a higher in vivo Chl a absorption coefficient and higher photosynthetic efficiency on a Chl a basis, although the two algae showed somewhat similar light‐response curves on a Chl a basis. Both species showed similar Chl a/Chl c and Chl a/fucoxanthin ratios, and similar dark respiration rates and light compensation points. In addition, they also showed similar convexities in their light‐response curves and no differences in their light saturation of FV/FM. Room temperature chlorophyll fluorescence induction measurements of fronds incubated in 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea (DCMU) suggest that both species may have a similar PSII absorption cross section. Thus, L. abyssalis appears to optimize its light absorption at very low light intensities, not by increasing the pigment content, but by absorbing light more efficiently. However, L. abyssalis was more sensitive to photoinhibition than L. digitata and showed no recovery of FV/FM and O2 evolution after a photoinhibitory treatment, even with a subsequent exposure to 24 h of dim light. L. digitata, on the other hand, recovered its photosynthetic capacity within 6 h under dim light. These results suggest that photosynthetic light‐induction curves based on Chl a are not a good indicator of either the photosynthetic capacity or the sensitivity to photoinhibition when macroalgae of different species are being compared. Based on their light‐response and photoinhibition characteristics, we suggest that L. abyssalis, a deep‐water oceanic macroalgae, is an atypical shade alga whereas L. digitata has the properties of a sun alga.

Variação espaço-temporal de populações de Hypnea musciformis (Rhodophyta, Gigartinales) na baía de Sepetiba e Armação dos Búzios, RJ, Brasil

Three populations of H. musciformis were analyzed throughout Rio de Janeiro State; two sublittoral epiphytic populations located in the Sepetiba bay (Mangaratiba municipality), and one intertidal epilithic population on the shore facing the open sea (Rasa beach, Armacao dos Buzios municipality). These populations were analyzed for seasonality in biomass production, the accompanying flora species, and the possible interactions with some environmental factors. The biomass production of H. musciformis was different at each site, water movement, sunlight, accompanying flora, and the relation between the epiphyte and host, Sargassum spp., caused different effects on biomass production in different populations.

Inhibitory Effect of Extracts of Brazilian Marine Algae on Human T-Cell Lymphotropic Virus Type 1 (HTLV-1)-Induced Syncytium Formation In Vitro

Extracts from four species of Brazilian marine algae collected from the Rio de Janeiro State coast were screened to determine the inhibitory effect on HTLV-1-induced syncytium formation. Before performing the syncytium inhibition assay the 50% cytotoxic dose (CyD50) of the algal extracts was evaluated. The antiviral test was carried out in HeLa cells co-cultured with HTLV-I infected T-cell line (C91/PL cells) in the presence of marine algal extracts in the concentration inferior to that corresponding to the CyD50. It was observed that co-cultured cells exposed to Ulva fasciata extract showed 60.2% syncytium inhibition at a concentration of 2.5%. At 5% concentration, Sargassum vulgare and Vidalia obtusiloba extracts presented 78.8 and 76% syncytium inhibition, respectively. The best inhibitory activity was observed with Laminaria abyssalis that presented 100% syncytium inhibition at a concentration of 2.5%. This work shows that extracts of marine algae, mainly L. abyssalis extract, are able to inhibit the cell-to-cell contact essential for the spreading of the virus and could be useful to prevent the infection.

Antiviral activity of extracts from Brazilian seaweeds against herpes simplex virus

Organic extracts of 36 species of marine algae (sixteen species of Rhodophyta, eight species of Ochrophyta and twelve species of Chlorophyta) from seven locations on the Brazilian coast were evaluated for their anti-HSV-1 and anti-HSV-2 activity resistant to Acyclovir (ACV). Activity tests in crude extracts, followed by the identification of the major compounds present, were performed for all species. The chemical profiles of all crude extracts were obtained by 1H-NMR and 13C-NMR spectroscopy. The percentage of extracts with antiviral activity was higher for HSV-1 (86.1%) than for HSV-2 (55.5%). The green algae Ulva fasciata and Codium decorticatum both showed the highest activity (99.9%) against HSV-1, with triacylglycerols and fatty acids as the major components. The red alga Laurencia dendroidea showed good activity against HSV-1 (97.5%) and the halogenated sesquiterpenes obtusol and (-)-elatol were identified as the major components in the extract. Against HSV-2, the green alga Penicillus capitatus (Chlorophyta) and Stypopodium zonale (Ochrophyta) were the most active (96.0 and 95.8%). Atomaric acid, a meroditerpene, was identified as the major secondary metabolite in the S. zonale extract. These results reinforce the role of seaweeds as important sources of compounds with the potential to enter into the pipeline for development of new drugs against herpes simplex.

Two New Flat Species of Gracilaria (Gracilariales, Rhodophyta) From Brazil: G. Abyssalis sp. nov. and G. Brasiliensis sp. nov

C.F.D. Gurgel, S. Fredericq, J.N. Norris and Y. Yoneshigue-Valentin. 2008. Two new flat species of Gracilaria (Gracilariales, Rhodophyta) from Brazil: G. abyssalis sp. nov. and G. brasiliensis sp. nov. Phycologia 47: 249–264. DOI: 10.2216/06-59.1 A recent survey of the Brazilian Gracilariaceae (Rhodophyta, Gracilariales) flora aided by molecular-based phylogenetic analyses and comparative morphological data revealed two unidentified flat species of Gracilaria described here: G. abyssalis sp. nov. and G. brasiliensis sp. nov. Gracilaria abyssalis is a deep-water species characterized by a conspicuous holdfast; a long, branched, robust stipe; irregular to sympodial branching of the thallus; occasional presence of midrib; and an extensive range of broad blade morphologies. Gracilaria brasiliensis is a shallow intertidal species characterized by an inconspicuous stipe (< 1 cm), regular dichotomously branched thalli, and narrow blades and rounded apices. DNA sequence analyses of the chloroplast-encoded rbcL gene showed that flat species of Gracilaria in the western Atlantic belong to two distinct lineages. Maximum parsimony results placed G. brasiliensis as a member of the G. mammillaris clade with no support, while Bayesian results identified this species as a disntict new independent lineage. Furthermore, it was found that G. cuneata and G. curtissiae are recently diverged sister species and that rbcL phylogenetic distances among the morphologically distinct G. intermedia and G. yoneshigueana are quite small.

Micropropagation as a tool for sustainable utilization and conservation of populations of Rhodophyta

Micropropagation as a tool for sustainable utilization and conservation of populations of Rhodophyta. Micropropagation, or in vitro clonal propagation, allows the production of a large number of individuals within a short period. These micropropagated clones could be used as seedlings for seaweed cultivation, avoiding collection from natural beds. Consequently, there has been an increasing interest in micropropagation as a tool for preservation of populations of marine red algae on the Brazilian coast and for the sustainable production of raw material for commercial exploration. This paper reviews the literature on tissue culture and micropropagation of red algae published during the three last decades. Based on the literature, we can conclude that the regeneration process is complex and diversified in different species of Rhodophyta and that the success of micropropagation depends on this process. Species belonging to the orders Bangiales and Ceramiales showed low potential for regeneration, while Gigartinales species showed the highest potential for regeneration. Micropropagation of commercially important red algae is fundamental for the conservation of natural populations by providing seedlings for cultivation and for germplasm collections, both for the conservation of genetic diversity and for biotechnological applications.

Diterpenes from the Brown Alga Dictyota crenulata

The crude extract of the Brazilian brown alga Dictyota crenulata was analyzed by NMR spectroscopy and HRGC-MS techniques. Seven diterpenes were identified: pachydictyol A, dictyodial, 4β-hydroxydictyodial A, 4β-acetoxydictyodial A, isopachy-dictyol A, dictyol C and dictyotadiol. Xeniane diterpenes have previously been found in D. crenulata from the Pacific Ocean. The results characterize D. crenulata as a species that provides prenylated guaiane (group I) and xeniane diterpenes (group III), thus making it a new source of potential antiviral products.

Alterações na composição florística das algas da Praia de Boa Viagem (Niterói, RJ)

During the past three decades, the Guanabara Bay suffered continuous degradation, leading to severe changes in the surrounding area and environmental damages. Besides significant loss of its natural landscape, the quality of its water decreased with continuous disposal of non-treated domestic organic sewage and industrial effluents. The present study aimed to survey the algal flora of Boa Viagem beach (Niteroi, RJ) and to compare it with information gathered three decades ago. Results showed a decrease of 30 taxa (49%) of the algal species and an increase of 14 species (23%) in comparison with algal flora recorded three decades ago. The actual algal flora is dominated by Ulva fasciata Delile and Enteromorpha compressa (L.) Nees, species indicative of organic pollution. These results elucidate the environmental impacts caused upon the macroalgae community of the Guanabara Bay during throughout the period.