Organotin Compounds (OTCs) in Saccharina latissima (Phaeophyceae) from the Barents Sea

Doklady Biological Sciences - The degree of contamination of Saccharina latissima, the dominant species among macrophyte algae in the sublittoral zones of the Kola Bay and Eastern Murman of the...     

Effects of site,depth and sori origin on the growth and minerals composition of cultivated Saccharina latissima (Phaeophyceae) in the north of Norway

Journal of Applied Phycology - Interest in the cultivation of Saccharina latissima is increasing in the north of Norway. In the present study, S. latissima was cultivated at two sites (Kraknes and...     

Morphological and physiological plasticity of Saccharina latissima (Phaeophyceae) in response to different hydrodynamic conditions and nutrient availability

Journal of Applied Phycology - Morphology and physiology are two key aspects of the adaptation of kelp to varying environments. Some of these kelp responses to co-occurring highly hydrodynamic...     

Development of Saccharina latissima (Phaeophyceae) kelp hatcheries with year-round production of zoospores and juvenile sporophytes on culture ropes for kelp aquaculture

Saccharina latissima is attractive for industrial cultivation for different usages, such as biofuels, feed supplements, and derivation of chemicals. A continuous supply of kelp sporelings throughout the year may ensure a year-round production of kelp juveniles on ropes. In this study, induction of sporangial areas (sorus portions) on the blade of S. latissima was performed throughout the year at three locations: Trondheim (Norway), Grenaa (Denmark), and Sylt island (Germany). The results indicate that a year-round sorus induction in S. latissima is possible and that this induction is controlled by applying short-day treatment of adult sporophytes throughout the year and by the removal of the basal blade meristem. The artificially induced and released zoospores formed viable sporelings at all seasons, but cultivation in the sea in Norway was successful only during autumn, winter, and spring, while the growth conditions were poor during the summer. The results are important for industrial scale-up and continuous production of kelp biomass.     

Lipid content and fatty acid consumption in zoospores/developing gametophytes of Saccharina latissima (Laminariales, Phaeophyceae) as potential precursors for secondary metabolites as phlorotannins

Phlorotannins are considered inter alia to act protective to a variety of stressors, while lipids in spores are known to fuel various metabolic processes during spore release and settlement. Here, phlorotannin production in zoospores/juvenile gametophytes in relation to lipid metabolism was investigated for the first time in order to study-related metabolic costs. The experiment was carried out in Ny-?lesund (Svalbard, Arctic) within the development from spores to juvenile gametophytes of the brown alga Saccharina latissima over 20 days. In the release stage, the total phlorotannin content of single zoospores was 1.5 × 10⁻⁷ μg and 1.9 × 10⁻⁷ μg in the surrounding medium. Upon release, the total amount of lipids was 1.76 × 10⁻⁵ μg lipid zoospore⁻¹ containing the major fatty acids 16:0 and 18:0, 18:1(n-9), 18:2 (n-6), 18:3(n-3), 20:4(n-6), and 20:5(n-3). During development from spores to gametophytes, a decrease in fatty acids was observed via electron microscopy and a decrease in the fatty acid 18:1(n-9) from 45 to 30% was measured by gas chromatography in particular. While phlorotannin content within the spores remained stable, phlorotannins accumulated in the surrounding medium of gametophytes to 4.0 × 10⁻⁷ μg phlorotannins spore⁻¹ indicating exudation processes. Results obtained support the key and multifunctional role of lipids in zoospore/gametophyte metabolism and may indicate that gametophytes of S. latissima need approximately 10 days to switch to photo-autotrophic strategies, becoming independent of storage lipids. In addition, fatty acids might represent an essential energy source to fuel adaptive responses.     

Protective function of silicon deposition in Saccharina japonica sporophytes (Phaeophyceae)

We investigated biogenic silica deposition in sporophytes of kelp, Saccharina japonica (Laminariaceae). Silicon content was measured in different sporophyte regions and there was a trend for the silicon content to increase longitudinally from the stipe-blade transition to apical regions. The transverse trend was for the content to be higher in the marginal region than in the medial region. The silicon content was also higher in the scar and sorus regions compared with the adjacent vegetative regions. High silicon content was detected in the margin of the disc and in the sorus region of cultured sporophyte discs. Moreover, rhodamine 123 staining suggested that silicon was deposited in the mouth of the marginal wound of the disc. Rhodamine 123 fluorescence was also detected in the paraphyses and mucilaginous caps of sori. These results suggest that silicon plays important roles in tissue protection and vegetative tissue wound healing. It is also suggested that silicon is required for the protection of reproductive tissues. We also discuss the physiological and ecological roles of biogenic silica deposition in kelp and its management in cultivated fields.     

Effects of ambient calcium concentration on morphological form of callus-like cells in Saccharina japonica (Phaeophyceae) sporophyte

Explants obtained from young sporophytes of Saccharina japonica were cultured in an artificial medium with different concentrations of Ca²⁺ (0–20?mM). The culture with 10?mM Ca²⁺ promoted the formation of unpigmented filamentous callus-like cells in the cortical layer. In contrast, explants cultured with 5?mM Ca²⁺ formed pigmented round callus-like cells in the epidermis at a high percentage. The thallus regeneration rate of explants in 5?mM Ca²⁺ was ten times higher than those of explants cultured in 10?mM Ca²⁺. Ambient Ca²⁺ concentrations also influenced the production of radical oxygen species (ROS) in explants. Explants cultured in 10?mM Ca²⁺ produced higher ROS than did those cultured in 5?mM. The ROS production was histologically observed mainly in the plasma membrane of callus-like cells using 2′, 7′-dichlorodihydrofluorescein diacetate. Moreover, a nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor, diphenyleneiodonium chloride, inhibited the ROS production with propagation of filamentous callus-like cells. These results suggest that Ca²⁺ concentration in medium influences the development of callus-like cells and thallus regeneration by affecting NADPH oxidase activity and ROS production in the plasma membrane of the callus-like cells. Therefore, the morphological form of callus-like cells and the development of thallus will be controlled by Ca²⁺ concentration in the medium.     

Comparing salinity tolerance in early stages of the sporophytes of a non-indigenous kelp (Undaria pinnatifida) and a native kelp (Saccharina latissima)

The short-term effects of low salinities on the survival of germlings of an introduced kelp Undaria pinnatifida and a native kelp Saccharina latissima were assessed under laboratory conditions. This experiment was designed to compare the differential stress tolerance to salinity of the early life history stages of sporophytes of these two kelps that co-occur on European Atlantic coasts. Germlings (young sporophytes) of both species were exposed for 4 days to salinities ranging from 31 (control) to 26, 21, 16, 11, and 6 psu. Afterwards, they were post-cultured in control seawater (31 psu) for another 4 days to corroborate the viability of injured germlings. Results showed that germlings of the introduced kelp were less resistant to low salinity, surviving to as low as 16 psu; whereas the germlings of the native kelp survived in salinities as low as 11 psu. Despite the observed differences, both species are relatively tolerant to low salinity. Our observations also indicated that, at least in a short term, gametophytes of both species were able to survive in salinities as low as 6 psu. The significance of low-salinity tolerance to the distribution of these kelps and for their offshore cultivation is discussed.     

Accumulation,effects on growth,and localization of zinc in Padina gymnospora (Dictyotales,Phaeophyceae)

The ability of young plants of the brown alga Padina gymnospora to tolerate and accumulate zinc was determined for different zinc concentrations in seawater over a period of 21 days. This species, among 10 macroalgae species studied in a contaminated coastal area near Rio de Janeiro city, presented the highest zinc contents. The accumulation of zinc by this species determined from in vitro experiments increased approximately linearly with the zinc concentration in the water. A steady state was not reached even for high concentrations (1000 µg 1^–1). Analytical electron microscopy techniques used for subcellular localization of this metal showed that the zinc was present as dense granules along the cell walls, starting in a region 15 to 25 cells away from the thallus apex, but being absent in the cytoplasm of viable cells. It is suggested that the cell walls play the main role in the zinc accumulation in Padina gymnospora.This paper is dedicated in honor of Prof. Carlos Chagas Filho, founder of the Institute of Biophysics, on the occasion of its 50^th anniversary     

Population studies of Laminaria hyperborea from its northern range of distribution in Norway

Eight populations of Laminaria hyperborea from wave-exposed localities in Finnmark (70–71°N) were compared with two populations in Vega (65°N). Standing stock in shallow water (3–5 m) was within the same range in the two areas (6–16 kg fr. wt. m^–2). Both the highest and lowest value of standing stock were registered in Finnmark. Degree of wave-exposure was determined by the numbers of sectors exposed to open sea at each locality, with each sector given a relative wind force value. The most wave-exposed locality in Vega had a slightly higher annual biomass production as a function of plant age compared with the populations from Finnmark within a similar range of wave exposure. Of the two localities in Vega the most wave-exposed one had a higher annual biomass production per plant than the more sheltered one. The most wave-exposed locality examined was situated in Finnmark and exhibited the lowest annual biomass production per plant. Recruits (one-year-old plants) were found at all the localities except at one locality in Finnmark. The plants reached a higher age in Finnmark (13–18 years) than in Vega (8–9 years).     

Taxonomy and distribution of Sargassum (Phaeophyceae) in the Gulf of Thailand

Ten species of Sargassum (Sargassaceae, Phaeophyceae) were found along the Gulf of Thailand. Morphological characteristics of Sargassum baccularia (Mertens) C.A. Agardh, S. binderi Sonder, S. cinereum J.G. Agardh, S.crassifolium J.G. Agardh, S. longifructum Tseng et Lu, S. oligocystum Montagne, S. polycystum C.A. Agardh, S. siliquosum J.G. Agardh, S. swartzii (Turner) C.A. Agardh and one unidentified species were examined and are described in detail. The most common species were S. polycystum distributed widely in almost all the study sites, S. crassifolium restricted to Prachuap Khirikhan Province, S. longifructum restricted to Chumphon Province, S. siliquosum restricted to Surat Thani Province and one unidentified species restricted to Songkhla Province. Three species (S. cinereum, S. longifructum and S. swartzii) are new records for the algal flora of Thailand. Five species (S. baccularia, S. cinereum, S. longifructum, S. polycystum and the unidentified species) belong to the section Zygocarpicae (J.G. Agardh) Setchell.     

Glycolate metabolism and subcellular distribution of glycolate oxidase in Spatoglossum pacificum (Phaeophyceae, Chromophyta)

Seven enzymes participating in glycolate metabolism were demonstrated to be present in crude extract of the brown alga Spatoglossum pacificum Yendo. These were phosphoglycolate phosphatase, glycolate oxidase, glutamate-glyoxylate aminotransferase, serine hydroxymethyltransferase, amino acid-hydroxy-pyruvate aminotransferase, hydroxypyruvate reductase and catalase. Malate synthase, which is involved in glycolate metabolism in the xanthophycean alga, could not be detected. On demonstration of subcellular distribution of glycolate oxidizing enzymes by linear sucrose density gradient centrifugation, glycolate oxidase was detected in the same fraction at a density of 1.23 g cm^?3 with catalase: that is, the marker enzyme of peroxisome and serine hydroxymethyltransferase was found in the same fraction at a density of 1.21 g cm^?3 with isocitrate dehydrogenase, the marker of mitochondria. From the present data, it is proposed that the brown alga Spatoglossum possesses the ability to metabolize glycolate to glycerate via the pathway which may be similar to that of higher plants.     

Pollination partners of Mucuna macrocarpa (Fabaceae) at the northern limit of its range

Mucuna macrocarpa is a plant found in tropical and subtropical regions that requires an “explosive opening.” Explosive opening is the process that exposes the stamen and pistil from the opening of the carina. This process is needed for cross pollination; however, the plant cannot open itself and opening by an animal is needed. The most common opener of Mucuna flowers is several nectar‐eating bats (e.g., Syconycteris), but the flying fox, Pteropus dasymallus, is the only opener of M. macrocarpa on the subtropical island of Okinawajima. Here, we present the explosive openers and possible pollinators in the northernmost and temperate Kamae region, Kyushu, Japan, where nectar‐eating bats are absent. The Japanese macaque, Macaca fuscata, and the Japanese marten, Martes melampus, were the explosive openers observed during our survey in Kamae. Martens opened flowers using their snout in a manner similar to that of the flying fox, whereas macaques opened flowers using their hands. This is the first time that an animal has been observed opening these flowers with its hands rather than snout. In total, 97% (n = 283) of explosively opened flowers were opened by macaques, and the macaque largely contributed to the overall flower opening. Because many pollen grains become attached to the explosive openers, they are considered to be primary pollinators. Furthermore, two bee species, Apis cerana japonica and Bombus ardens ardens, also visited opened flowers and collected pollen, and they were possibly secondary pollinators.