Measurement of the adhesion of a desmid to a substrate

The paper describes a hydrodynamic method by which the adhesive strength of the mucilage produced from the apical proes of Closterium acerosum has been measured. An equation used to determine the drag force on the cells is presented, as are some measured adhesive strengths of the Closterium mucus to glass slides.     

Utility of rbcS gene as a novel target DNA region for brown algal molecular systematics

The usefulness of molecular phylogenetic studies has increased remarkably as the quantity and quality of available DNA sequences has increased. When compared with the progress that has occurred in angiosperms and animals, there have been relatively few target DNA regions identified for use in taxonomic studies of brown algae. Therefore, in this study, we developed a new set of primers to amplify Rubisco small subunit (rbcS) gene sequences and determined the rbcS gene sequences of various species of brown algae including those belonging to Dictyotales, Ectocarpales, Fucales and Sphacelariales. The level of sequence variations in the rbcS gene varied according to the brown algal lineages. When focusing on the relationship of species within the genus Sargassum, the rbcS gene sequences provided useful information regarding the phylogenetic relationship among sections of the subgenus Bactrophycus. Based on the broad applicability and phylogenetic utility of the rbcS gene, we suggest that the sequence be used as a new target region for the molecular systematics of brown algae.     

OPTIMIZATION OF SOME HEAVY METALS BIOSORPTION BY REPRESENTATIVE EGYPTIAN MARINE ALGAE1

Marine algae—as inexpensive and renewable natural biomass—have attracted the attention of many investigators to be used to preconcentrate and biosorb many heavy metal ions. Impressed by this concept, the metal uptake capacity of Egyptian marine algae was examined using representatives of green and brown algae, namely, Ulva lactuca L. and Sargassum latifolium (Turner) C. Agardh, respectively. The biosorption efficiencies of Cu²⁺, Co²⁺, Ni²⁺, Cd²⁺, Hg²⁺, Ag²⁺, and Pb²⁺ ions seem to depend on the type of the algae used as well as the conditions under which the uptake processes were conducted. It was demonstrated that a pH range of 7.5–8.8 was optimum for the removal of the tested metals. Similarly, the uptake process was markedly accelerated during the first 2 h using relatively low metal level and sufficient amounts of the dried powdered tested algae.     

Life history flexibility allows Sargassum polyceratium to persist in different environments subjected to stochastic disturbance events

Stochastic, stage-based matrix models were used to investigate the life history strategy of the seaweed Sargassum polyceratium in shallow intertidal and deep-water (18 m) populations. Matrix models were parameterized with 3 years of yearly transitions among four plant stages quantified from three bays on Curaçao (Netherlands Antilles). There were years without a storm, with a moderate (winter) storm and with a strong storm (Hurricane Lenny). The stochastic population growth rate varied among populations (λ_s: 0.54–1.03) but was not related to depth. The most important stages for population growth were reproductive adults (shallow) and non-reproductive adults (deep). With the occurrence of storms, vegetative growth (mainly deep) and fertility (mainly shallow) became the most important processes. Recruitment (shallow) and regeneration from holdfasts (deep) only contributed to population persistence after the hurricane. It is concluded that S. polyceratium has a flexible, depth-dependent, life history strategy that is adjusted to disturbance events.     

Inhibition of mouse liver lipid peroxidation by high molecular weight phlorotannins from Sargassum kjellmanianum

The inhibitory effects of high molecularweight phlorotannins (HMP) from Sargassum kjellmanianum on mouse liverlipid peroxidation were investigated byspectrophotometric methods. The content ofmalondialdehyde (MDA) in liver samples wasmeasured by TBA (thiobarbituric acid)assay. It showed that HMP significantlyinhibited the generation of MDA invivo and in situations induced byCCl₄ and Fe²⁺-Vc (ascorbic acid),and significantly decreased membraneswelling of mouse liver mitochondria,compared with controls (p<0.01). HMP werefound to have strong anti-oxidativeactivity in inhibiting mouse liver lipidperoxidation.     

羊栖菜中褐藻糖胶的组分分离及分析

为了确定羊栖菜褐藻糖胶中的活性组分 ,用分子量结合硫酸化程度的分级方法将其分成不同组分。经热水抽提的羊栖菜多糖 ,将去除褐藻胶、海带淀粉后剩余的褐藻糖胶经过DEAE—Sepharose离子交换色谱柱和Sepharose 4B凝胶层析柱被分成 5个褐藻糖胶组分。 5个组分中硫酸基和岩藻糖近似的分子数量之比分别为 1.863、0 .0 68、1.2 2 9、1.62 9,1.0 10 ;平均分子量分别为 2 .0× 10 4 、2 .2× 10 4 、8.2× 10 4 、2 1.4× 10 4 、32 .0× 10 4 ;百分含量分别为 8.6%、2 2 .9%、4 8.5 %、5 .7%、14.3%。     

海蒿子多糖DEⅠ、DEⅡ组分分离纯化、结构及抗癌活性研究

海蒿子干粉经热水抽提、乙醇沉淀、DEAE-Sephadex A-25柱层析分离,得到多糖DEⅠ、DEⅡ,总糖含量分别为52.40%、38.8%.经酸降解、薄层层析、气相色谱-质谱分析,证明其单糖组成均为木糖、岩藻糖、半乳糖、果糖、甘露糖、葡萄糖.其中岩藻糖含量最高.多糖DEⅠ、DEⅡ对P388肿瘤具有抑制活性.     

Spatial associations among palatable and unpalatable macroalgae: A test of associational resistance with a herbivorous amphipod

Associational resistance is the process by which plants may gain protection from spatial associations with neighbouring plants. We tested whether association with an unpalatable alga, Dictyopteris acrostichoides, affects the abundance and colonisation behaviour of the herbivorous amphipod Peramphithoe parmerong on its preferred host alga Sargassum linearifolium. Despite predictions, natural densities on S. linearifolium when surrounded by D. acrostichoides were higher than on isolated individuals of S. linearifolium. Colonisation experiments in the laboratory and the field tested the hypotheses that the observed variation in field abundance with algal neighbourhood was due to variation in the size of habitat patches, physical obstruction of host finding by D. acrostichoides and variation in the relative abundance of S. linearifolium and D. acrostichoides. None of these possible mechanisms was found to significantly alter rates of amphipod colonisation on the scales of individuals selecting among algal pieces in the laboratory or among habitat patches in the field. The failure of colonisation processes to explain observed variation in natural amphipod densities suggests that post-colonisation processes such as survival or emigration may vary with the spatial associations among algae.     

Early development of germlings of <Emphasis Type="Italic">Sargassum thunbergii</Emphasis> (Fucales,Phaeophyta) under laboratory conditions

Morphology and culture studies on germlings of Sargassum thunbergii (Mertens et Roth) Kuntze were carried out under controlled laboratory conditions. Growth characteristics of these germlings grown under different temperatures (from 10 to 25°C), irradiances (from 9 to 88 μmol photons m⁻² s⁻¹), and under blue and white light conditions are described. The development of embryonic germlings follows the classic “8 nuclei 1 egg” type described for Sargassaceae. Fertilized eggs spent 5–6 h developing into multicellular germlings with abundant rhizoids after fertilization. Under conditions of 20°C, 44 μmol photons m⁻² s⁻¹ and photoperiod of 12 h, young germlings with one or two leaflets reached 2–3 mm in length after 8 weeks. Temperature variations (10, 15, 20, 25°C) under 88 μmol photons m⁻² s⁻¹ significantly influenced the growth rate within the first week, although this effect became less obvious after 8 weeks, especially at 15 and 20°C. Variation in germling growth was highly significant under different irradiances (9, 18, 44, 88 μmol photons m⁻² s⁻¹) at 25°C. Low temperature (10°C) reduced germling growth. Growth of germlings cultured under blue light was lower than in white light. Optimal growth of these germlings occurred at 25°C and 44 μmol photons m⁻² s⁻¹.     

Abundance of drifting seaweeds in eastern East China Sea

Drifting seaweeds play important ecological roles in offshore waters. Recently, large amounts of drifting seaweed rafts were found in the eastern East China Sea between the continental shelf and the oceanic front of the Kuroshio Current. However, so far there have been no quantitative reports about this particular area. Two research cruises were organized to survey abundance and standing crop of drifting seaweeds in eastern East China Sea in May 2002 and March 2004, using visual census and net sampling of drifting seaweeds. Visual census data were composed of drifting seaweed raft diameter, perpendicular distance from the transect (navigation course of the research vessel) to the raft, and positions. Using these data, we calculated the “effective stripe width” using the DISTANCE software. Drifting seaweed abundance (composed exclusively of Sargassum horneri) in waters located between the continental shelf peripheral area and the Kuroshio oceanic front was estimated to be higher than in any other area within eastern East China Sea in March and May. Abundance means in May 2002 and March 2004 were 6.14 and 29.05 rafts km⁻², respectively, while standing crop reached 126.81 and 20.35 kg km⁻² (wet weight). Mean diameter and drifting seaweed rafts in May 2002 were significantly greater than in March 2004, reflecting seasonal growth of Sargassum horneri.