Sargassum horneri C. Agardh space capacity estimation reveals that thallus surface area varies with wet weight.

Sargassum horneri C. Agardh is an important commercial edible seaweed species in east Asia. Benthic beds and floating rafts in coastal areas make excellent habitats for marine organisms to feed, hide, and spawn. Many commercially important fish species such as Japanese anchovy (Engraulis japonicus), yellowtail (Seriola quinqueradiata), and Japanese horse mackerel (Trachurus japonicus) live in seaweed beds. Chinese and Japanese fisherman rely on S. horneri beds as productive fish harvest areas. The Zhejiang government in China set a total allowable catch standard, to preserve the Ma'an Islands ecosystem, which is a marine protected area. In this study we analysed the association between weight and one-sided surface area of S. horneri beds, and calculated the ratio of one-sided surface area to change in wet weight over time. We collected samples from December 2014 to May 2015. Approximately 1 g of S. horneri biomass provided ~15 cm2 of one-sided surface area available to marine organisms. These calculations can be used as a reference regarding potential space to improve total allowable catch standard management in S. horneri beds, through the estimation of space capacity of seaweed beds.

The brown seaweed Sargassum cymosum: changes in metabolism and cellular organization after long-term exposure to cadmium.

Sargassum cymosum was exposed to cadmium (Cd) to determine any physiological and ultrastructural effects. To accomplish this, S. cymosum samples were cultivated under photosynthetic active radiation (PAR) and Cd (0, 0.1, 0.2, 0.4 and 0.8 mg L-1) during 7 and 14 days in laboratory-controlled conditions (0 mg L-1 Cd at both exposure times as control). Seaweeds had high retention capacity (over 90 %) for both exposure times. Growth rates showed significant increases by 14 days, especially for 0.1 and 0.4 mg L-1 Cd. Photosynthetic parameters were unaffected by Cd treatments. Chlorophyll contents were present in higher concentrations for all Cd treatments compared to respective control. Carotenoid profile showed significant differences in total composition and proportion of fucoxanthin and ß-carotene, and no lutein was detected at 14 days. Phenolic and flavonoid compounds showed major accumulation at 14 days. Transmission electron microscopy (TEM) analyses presented major alterations in Cd-treated samples, when compared with respective control, in particular disorganization of cell wall fibrils. When compared to respective control samples, multivariate analyses showed disparate and complex interactions among metabolites in Cd-exposed seaweeds, giving evidence of physiological defence response. Thus, it can be concluded that Cd is a stressor for S. cymosum, resulting in physiological and structural alterations related to defence mechanisms against oxidative stress and toxicological effects resulting from long-term metal exposure. However, in the present paper, some observed changes also appear to result from acclimation mechanisms under lower concentration of Cd relative to the tolerance of S. cymosum to experimental conditions.

Ultrastructural and structural characterization of zygotes and embryos during development in Sargassum cymosum (Phaeophyceae, Fucales).

This study investigates the pattern and performance of cellular structures during the early development of zygotes and embryos of Sargassum cymosum. The early development S. cymosum germlings has already been characterized and compared with the pattern of development established for all fucoid algae, in which the zygote remains attached to the receptacle by mucilage during the establishment of polarity and early cell division. As in the algae Fucus and Silvetia, the first division is transverse across the longer axis of the zygote of S. cymosum. However, the cell that will give rise to the rhizoids is not determined in the first division; rather, the formation of this cell occurs with the second division, forming a small cell in the embryo shaded site. Stabilizing polarity during the process of forming a multicellular embryo occurs rapidly. During development, significant cytoplasmic alterations take place. Initially, the cytoplasm shows large clusters of phenolic compounds located in specific parts, but later, in the course of development, these compounds are dispersed in the cytoplasm, although a significant amount remains confined to the nucleus. Moreover, to produce more zygotes and higher growth rates for the germlings, the best conditions found for the species S. cymosum were 22 and 26 °C, respectively.

Effect of heavy metals (Cu, Pb, and As) on the ultrastructure of Sargassum pallidum in Daya Bay, China.

Concentrations of Cu, Pb, and As were determined in seawater, surface sediment, Sargassum pallidum collected from the Daya Bay, China. The influence of metal contamination on the marine alga was investigated at chemical and ultrastructural level. Mean concentrations of Cu (19.44 mg kg(-1)) and Pb (33.99 mg kg(-1)) were found to be high in sediment, whereas concentration of As (122.29 mg kg(-1)) in S. pallidum was higher than that in water and sediment. The ultrastructure of S. pallidum cells was anomalous and aberrant. Energy-dispersive x-ray spectroscopic analysis revealed that the nanometal particles in the form of comparatively high-electron density substance diffused in the cell structures constituted by Cu, Pb, As, etc. There is a remarkable similarity or correspondence in the anomalous elements between the geochemistry and the botanic cell, and the heavy metals have potential hazardous effect on the ocean ecology system in Daya Bay.

Sargassum myriocystum mediated biosynthesis of gold nanoparticles.

Functionalized metal nanoparticles are unique in nature and are being developed for its specificity in drug targeting. In the present study, aqueous extract of Sargassum myriocystum is used for the biosynthesis of gold nanoparticles (AuNPs) by the reduction of chloroauric acid. The formation of nanoparticles reaction was complete within 15 min at 76 °C. The size, shape and elemental analysis of AuNPs were carried out using UV-visible absorption spectroscopy, FT-IR, TEM, SEM-EDAX, and XRD analysis. The newly formed AuNPs are stable, well-defined, polydispersed (triangular and spherical) and crystalline with an average size of 15 nm. The biomolecule involved in stabilizing AuNPs was identified using GC-MS.

Immunohistochemical localization of endogenous D-Aspartate in the marine brown Alga Sargassum fusiforme.

Immunohistochemical localization (cellular localization) of endogenous D-aspartate in the marine brown alga Sargassum fusiforme was investigated by the use of a specific polyclonal antibody raised against D-aspartate. D-Aspartate immunoreactivity was evident in the medullary layer in the blade of the alga, and weak staining was found in the cortical layer, whereas epidermal cells were found to lack D-aspartate. Within the cells of the layers, immunoreactivity was confirmed only in the cytosol and not in the cell wall, chloroplast, or vacuole. These results suggest that D-aspartate is present in S. fusiforme cells, and excludes the possibility that it is derived from attached or symbiotic organisms such as marine bacteria. This is the first report describing the localization of free D-aspartate in plant cells.

Biosorption of hexavalent chromium onto raw and chemically modified Sargassum sp.

Hexavalent chromium biosorption by raw algae is always accompanied with significantly high organic leaching. In this study, hydrochloric acid, sodium hydroxide, calcium chloride, formaldehyde, and glutaraldehyde were used for modification of raw Sargassum sp. seaweed (RSW), in order that the modified seaweed (MSW) has a lower organic leaching while the metal biosorption capacity is comparable to the RSW. The result shows that the chemical modification by 0.2% formaldehyde achieves such goals. The biosorption of both RSW and MSW is highly pH dependent. At the optimal pH of 2.0, the maximum biosorption capacities of MSW and RSW are 1.123 and 0.601 mmol g(-1), respectively. The surface treatment improves the reduction capacity of the biosorbents. The instrumental analysis demonstrates that the Cr(VI) biosorption is controlled by redox, ion exchange and coordination reactions, of which alcohol, carboxyl, amino and sulphonic groups play important roles. The complete uptake of hexavalent chromium is achieved in 20 h. The chemical reduction for Cr(VI) to Cr(III) is pH dependent and controls the overall chromium removal kinetics.

Influence of the drying conditions of Sargassum sp. alga on the bioadsorption of hexavalent chromium.

Industrial wastes containing synthetic organic compounds and heavy metals are among the most dangerous residues, whose growth has followed the increase in industrial activity. Heavy metals are readily assimilated into the food chain and therefore easily accumulated in the ecosystem. To remove heavy metals from aqueous solutions, marine algae may be used as adsorbents either in their natural form or after treatments by a cross-linking process to improve their mechanical resistance. Drying of biosorbents, such as marine algae, is mentioned in many previous works as a step preceding the adsorption/dessorption cycle. Concerning algae, drying of its fresh biomass allows for proper storage and enhances performance in the sorption of heavy metals. In this work, physical and morphological analyses of fresh and dried Sargassum sp. marine algae, harvested offshore São Sebastião, São Paulo state, Brazil, were performed in order to assess the influence of drying conditions on the biosorption process. Chromium concentrations were also determined in different parts of the algal structure before and after the biosorption process. The drying promoted structural changes in the algae, like shrinkage and porosity reduction. It was also observed that the chromium retention was dependent on the structural arrangement of the alga parts, in which the leaf was the major biosorbent.

[Description and histology identification of several algae of Sargassum sp].

This paper reported the description characters and microscopical identification of seven kinds of algae of Sargassum sp., Sargassum pallidum (Tum.) C. Ag., S. fusiforme (Harv.) Setch., S. horneri (Tum.) C. Ag., S. hemiphyllum (Turh.) C. Ag., S. thunbergii (Mert.) O'Kuntze, S. polycystum C. Ag. and S. kjellmanianum Yendo. The results revealed that there were clear differences in the description characters and microscopical identification of the seven kinds of algae of Sargassum sp. These studies provided a scientific basis for distinguishing crude drug of algae, developing and making use of alga natural resources of Sargassum sp.