Two trichodinid ectoparasites from marine molluscs in the Yellow Sea, off China, with the description of Trichodina caecellae n. sp (Protozoa : Ciliophora : Peritrichia)

The morphology and infraciliature of two ectoparasitic ciliates, Trichodina caecellae n. sp. and T. ruditapicis Xu, Song & Warren, 2000, parasitising the gills of marine molluscs from the Shandong coast of the Yellow Sea, China, were investigated following wet silver nitrate and protargol impregnation. T. caecellae was found on the small marine sand clam Caecella chinensis Deshayes and is distinguished mainly by the acute triangle-like blade, the very delicate central part and the needle-shaped ray. T. ruditapicis was studied based on four populations from three clams: two populations from Ruditapes philippinarum (Adams) and one each from Saxidomus purpuratus (Sowerby) and Solen grandis Dunker. All four populations fell within the range of morphometry and agreed closely in the overall appearance of the adhesive disc. However, variability was found in the denticle structure, especially in populations from different host clams. Our observations suggest that denticle morphology may be more or less variable between and within populations, and that such minor differences should not be overestimated. It should be emphasised that, except for the denticle morphology, the bright granules or circles in the centre of the adhesive disc represent another important feature facilitating the identification of this trichodinid species.

Sesquiterpenes from the Marine Red Alga Laurencia saitoi

Together with five known sesquiterpenes, EtOH extraction of Laurencia saitoi yielded four new compounds, including three sesquiterpenes and one norsesquiterpene derivative. Their structures and relative configurations were elucidated by spectroscopic methods, including 1D- and 2D-NMR (H-1,H-1-COSY, HMQC, HMBC, and NOESY), as well as low- and high-resolution mass-spectrometric analyses.

A NOVEL BROMOPHENOL FROM MARINE RED ALGA Symphyocladia latiuscula

2,3,6-Tribromo-4,5-dihydroxybenzyl ethyl ether (1), a new bromophenol, was isolated from the ethanol extract of marine red alga Symphyocladia latiuscula, with a known compound, 2,3,6-tribromo-4,5-dihydroxybenzyl methyl ether ( 2). Their structures were elucidated by spectroscopic analysis, including high-resolution mass spectroscopy, and 1 and 2-dimensional NMR techniques. Compounds 1 and 2 showed inhibitory activity against Staphyloccocus aureus with IC50 102 and 50 mu g/mL, respectively.

Screening marine algae from China for their antitumor activities

Thirty-nine species of marine algae collected from the coast of China were screened for their antitumor activities, and eight species Leathesia difformes, Polysiphonia urcedata, Scytosiphon lomentarius, Gloiopeliis furcata, Punctaria latifolia, Symphyocladia latiuscula, Rhodomela confervoides and Ulva pertusa showed potent cytotoxic activities. Three, Rhodomela confervoides, Scytosiphon lomentarius and Gloiopeliis furcata, were used for further investigation. More than 30 compounds were isolated and purified, and 14 bromophenols, 1 steroid and 1 carotene were identified by advanced spectroscopic methods including IR, MS, and NMR techniques. Amongst the 16 identified compounds, 7 showed vigorously selective activities against KB, Bel7402 and A549 cancer cells, and 6 bromophenols were new compounds.

Antibacterial bromophenols from the marine red alga Rhodomela confervoides

Two bromophenols, together with three known compounds, were isolated from the methanolic extract of the marine alga, Rhodomela confervoides. By means of MS and NMR spectroscopic analyses, they were identified as 3-bromo-4-[2,3-dibromo-4,5-dihydroxyphenyl] methyl-5-(hydroxymethyl) 1,2-benzenediol (1) and 3-bromo-4-[2,3-dibromo-4,5-dihydroxyphenyl] methyl-5- (ethoxymethyl) 1,2-benzenediol (2). Three known compounds were also isolated, namely 3-bromo-4-[2,3-dibromo-4,5-dihydroxyphenyl] methyl-5-(methoxymethyl) 1,2-benzenediol (3), 4,4'- methylenebis [5,6-dibromo-1,2-benzenediol] (4) and bis (2,3-dibromo-4,5-dihydroxybenzyl) ether (5). Compound 5 was the most active against five strains of bacteria with the MIC less than 70 mug/ml, while compounds 2, 3 and 4 exhibited moderate activity.

Grey relational analysis on the relation between marine environmental factors and oxidation-reduction potential

The effects of marine environmental factors-temperature (T), dissolved oxygen (DO), salinity (S) and pH-on the oxidation-reduction potential (ORP) of natural seawater were studied in laboratory. The results show an indistinct relationship between these four factors and the ORP, but they did impact the ORP Common mathematical methods were not applicable for describing the relationship. Therefore, a grey relational analysis (GRA) method was developed. The degrees of correlation were calculated according to GRA and the values of T, pH, DO and S were 0.744, 0.710, 0.692 and 0.690, respectively. From these values, the relations of these factors to the ORP could be described and evaluated, and those of T and pH were relatively major. In general, ORP is influenced by the synergic effect of T, DO, pH and S, with no single factor having an outstanding role.

Prediction of marine sediment corrosion by fuzzy clustering analysis

Along with the development of marine industries, especially marine petroleum exploitation, more and more pipelines are buried in the marine sediment. It is necessary and useful to know the corrosion environment and corrosiveness of marine sediment. In this paper, field corrosion environmental factors were investigated in Liaodong Bay marine sediment containing sulfate-reducing bacteria (SRB) and corrosion rate of steel in the partly sediment specimens were determined by the transplanting burying method. Based on the data, the fuzzy clustering analysis (FCA) was applied to evaluate and predict the corrosiveness of marine sediment. On that basis, the influence factors of corrosion damage were discussed.

Corrosion failure of marine steel in sea-mud containing sulfate reducing bacteria

The corrosion failure behavior of marine steel is affected by stress, which exists in offshore structures at sea-mud region. The sulfate reducing bacteria (SRB) in the sea-mud made the steel more sensitive to stress corrosion cracking (SCC) and weaken the corrosion fatigue endurance. In this paper, a kind of natural sea-mud containing SRB was collected. Both SCC tests by slow strain rate technique and corrosion fatigue tests were performed on a kind of selected steel in sea-mud with and without SRB at corrosion and cathodic potentials. After this, the electrochemical response of static and cyclic stress of the specimen with and without cracks in sea-mud was analyzed in order to explain the failure mechanism. Hydrogen permeation tests were also performed in the sea-mud at corrosion and cathodic potentials. It is concluded that the effect of SRB on environment sensitive fracture maybe explained as the consequences of the acceleration of SRB on corrosion rate and hydrogen entry into the metal.

Study on corrosion of steels in marine environment by corrosion simulation device

Three kinds of steels were studied using electrically connected hanging specimen in the corrosion simulation device and offshore long scale hanging specimen. The experimental results obtained by the two methods show that the device can better reflect the offshore corrosion environment. A Ni-Cu-P steel specimen was studied through analysis of the specimen's corrosion products and corrosion types. The surface of the samples before and after the removal of the rust layer produced by these two methods were observed and compared after some experiments. The microstructure of the corrosion products under different marine environments were analyzed and compared through IR. It indicated good correlation between the electrically connected hanging specimen method and the long scale hanging specimen method.