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Sporophytes of Laminaria digitata (L.) Lamour. were assayed for their content of accumulated iodine, which ranged from 0.4% of dry weight in adult plants up to 4.7% for young plantlets. Sporophyte tissue from Laminaria saccharina (L.) Lamour. and L. digitata took up iodide according to Michaelis-Menten kinetics. Hydrogen peroxide and various substances known to interfere with oxidative metabolism were shown to either inhibit or enhance the uptake of iodide, confirming that apoplastic oxidations play a key role in iodide uptake in Laminaria. Consistently, iodide uptake was triggered in L. saccharina protoplasts by incubation in the presence of hydrogen peroxide. Similarly, the uptake of iodide was enhanced in L. digitata gametophytes by addition of haloperoxidase, suggesting that this enzyme catalyses the oxidation of iodide by hydrogen peroxide and plays a key role in iodine uptake. Oxidative stress resulted in a marked efflux of the intracellular iodine. In both influx and efflux experiments, a marked proportion (10–30%) of the tracer was not accounted for, indicating volatilisation of iodine. The mechanism and possible functions of the accumulation of iodine by kelps are discussed. [ABSTRACT FROM AUTHOR]

Protoplast were isolated from a filamentous brown alga, Sphacelaria sp. (Sphacelariales, Phaeophyta), using alginate-lyases extracted from marine molluscs, and commercial pectinase and cellulase. Yields were about 4000 protoplasts per gram of fresh tissue. Different types of protoplasts, originating from apical, subapical, nodal and internodal cells, could be readily identified based on their size and pigmentation. Apical cells produced a higher percentage of protoplasts (approx. 2%), compared with other cell types. All apical-cell protoplasts regenerated into new thalli and most other types of protoplasts divided at least once in culture, but did not develop further. [ABSTRACT FROM AUTHOR]

Protoplasts were isolated from female gametophytes of Chondrus crispus (Stackh.) using commercial cellulase and various carrageenases prepared from marine bacteria. Depending on the nature of the donor tissue (apices or whole thallus, wild or cultivated strains), yields ranged from 1.0-8.5×10 protoplasts per gram of fresh tissue. Preincubating the tissue with a potassium chelator, Kryptofix 222, enhanced protoplast yields by 30-50 %. Based on staining with fluorescein diacetate most protoplasts were viable. A few protoplasts regenerated a cell wall and divided. [ABSTRACT FROM AUTHOR]

The entire nucleotide sequence containing the small-subunit ribosomal RNA gene ( SSU rRNA) from the mitochondrial genome of Chondrus crispus was determined. To our knowledge, this is the first sequence of a mitochondrial 16S-like rRNA from a red alga. The length of this gene is 1,376 nucleotides. Its secondary structure was constructed and compared with other known secondary structures from eubacteria and from mitochondria of land plants, green and brown algae, and fungi. Phylogenetic trees were built upon SSU rRNA sequence alignment from mitochondria and eubacteria. The results show that rhodophytes and chromophytes provide additional links in the evolution of mitochondria between the green plant lineage and the 'nonplant' lineages. [ABSTRACT FROM AUTHOR]

The purpose of this review is to present an account of our current understanding of the structure, organization and evolution of mitochondrial genomes, and to discuss the origin and evolution of mitochondria from the perspective recently provided by the extensive sequenc-ing of various mitochondrial genomes. Mitochondrial-en-coded protein phylogenies are congruent with nuclear phylogenies and strongly support a monophyletic origin of mitochondria. The newly available data from red-algal mitochondrial genomes, in particular, show that the structural and functional diversity of mitochondrial genomes can be accounted for by paralogous evolution. We also discuss the influence of other constraints, such as uniparental inheritance, on the evolution of genome organization in mitochondria. [ABSTRACT FROM AUTHOR]

Protoplasts were isolated from sporophytes and from gametophyte cultures of several species in the order Laminariales. For each example, the isolation and culture procedures were investigated systematically, to identify conditions leading to plant regeneration. After dedifferentiation through a filamentous stage, protoplasts isolated from adult Laminaria saccharina sporophytes regenerated polystichous bladelets. In contrast, cells isolated from Laminaria digitata sporophytes proved recalcitrant in culture, except when the donor plants were undifferentiated sporelings. The most critical factors for protoplast development were the origin of explants, the osmoticum used for cell isolation, cultivation in plain seawater, and the absence of stress during the first two weeks of culture. We also found that protoplast isolation from the sporophytes of members of the Laminariales results in the release of hydrogen peroxide, up to 5–120 μM final concentration in the macerating medium, a characteristic which may be related to protoplast recalcitrance. Protoplasts isolated from the gametophytic phase readily regenerated into normal gametophytes, capable of gametogenesis and producing sporophytes by fertilization. [ABSTRACT FROM AUTHOR]

The amounts of nuclear DNA in ten species of seaweeds belonging to the Rhodophyceae, Phaeophyceae, and Chlorophyceae were determined by flow cytometric analysis of nuclei isolated from protoplasts. Genome size was determined from the fluorescence of the nuclei stained with ethidium bromide. The size of the nuclear genome ranged from 0.13 pg per cell in the 1 C population of Ulva rigida to 3.40 pg per cell in the 2 C population of Sphacelaria sp. GC% analysis was based on staining with either Hoechst 33342 or mithramycin A, two fluorochromes specific for the bases A-T and G-C, respectively. Two models were used for the estimation of the proportion of guanine plus cytosine in the nuclear genome. The first one was based on the linear relationships mithramycin A fluorescence/G-C content and ethidium bromide fluorescence/total DNA content. The second model, based on the curvilinear relationships Hoechst 33342 fluorescence/A-T content and mithramycin A fluorescence/G-C content, resulted in comparatively more homogenous and consistent data and appears more accurate. Comparison with previous reports from other methods for the physical investigation of nuclear genomes shows that flow cytometry of nuclei isolated from protoplasts is an accurate, convenient and robust technique to assay for genome sizes and base pair composition in marine macroalgae. [ABSTRACT FROM AUTHOR]

Marine microbial diversity offers enormous potential for discovery of compounds of crucial importance in healthcare, food security and bioindustry. However, access to it has been hampered by the difficulty of accessing and growing the organisms for study. The discovery and exploitation of marine bioproducts for research and commercial development requires state-of-the-art technologies and innovative approaches. Technologies and approaches are advancing rapidly and keeping pace is expensive and time consuming. There is a pressing need for clear guidance that will allow researchers to operate in a way that enables the optimal return on their efforts whilst being fully compliant with the current regulatory framework. One major initiative launched to achieve this, has been the advent of European Research Infrastructures. Research Infrastructures (RI) and associated centres of excellence currently build harmonized multidisciplinary workflows that support academic and private sector users. The European Marine Biological Research Infrastructure Cluster (EMBRIC) has brought together six such RIs in a European project to promote the blue bio-economy. The overarching objective is to develop coherent chains of high-quality services for access to biological, analytical and data resources providing improvements in the throughput and efficiency of workflows for discovery of novel marine products. In order to test the efficiency of this prototype pipeline for discovery, 248 rarely-grown organisms were isolated and analysed, some extracts demonstrated interesting biochemical properties and are currently undergoing further analysis. EMBRIC has established an overarching and operational structure to facilitate the integration of the multidisciplinary value chains of services to access such resources whilst enabling critical mass to focus on problem resolution. [ABSTRACT FROM AUTHOR]