The in vitro effects of steroids,human chorionic gonadotropin and cyanoketone on germinal vesicle breakdown of striped mullet (Mugil cephalus L.) oocytes

The in vitro effects of steroids, human chorionic gonadotropin (HCG) and cyanoketone on germinal vesicle breakdown (GVBD) of striped mullet (Mugil cephalus L.) oocytes were investigated. All concentrations of HCG (5,10,50 I.U./ml), progesterone and pregnenolone at the highest concentrations(lug/ml) were moderately effective in inducing GVBD, whereas 17β-estrodiol, cortisol, testosterone, 11β-hydroxyandrostenedione and 11-ketotestosterone did not stimulate GVBD. 17α, 20βdihydroxy-4-pregnen-3-one (17α, 20βdiOHprog) and deoxycorticosterone (DOC) were the most potent steroids in stimulating final oocyte maturation. The results indicate that C21 hydroxylated steroids are potent inducers of final maturation in mullet. Further, co-incubations with 17β-estradiol, cortisol and testosterone did not alter the maturation-inducing effects of HCG or 17α,20βdiOHprog. Cyanoketone, a blocker of 3βHSD activity, was only partially effective in blocking GVBD induced by HCG. This suggests that Δ5 (pregnenolone derived) and Δ4 steroids may be involved in final oocyte maturation in this species.     

Effects of heavy metals （Pb^2＋ and Cd^2＋） on the ultrastructure, growth and pigment contents of the unicellular cyanobacterium Synechocystis sp. PCC 6803

The unicellular cyanobacterium Synechocystis sp. PCC 6803, a model organism known for its unique combination of highly desirable molecular genetic, physiological and morphological characteristics, was employed in the present study. The species was cultured in BG11 liquid medium contained various initial concentrations of Pb²⁺ and Cd²⁺ (0, 0.5, 1, 2, 4, 6 and 8 mg/L). The experiment was conducted for six days and the metal induced alterations in the ultrastructure, growth and pigment contents were assessed. Alterations in the ultrastructure of the Synechocystis sp. PCC 6803 cells became evident with the increased (>4 mg/L Pb²⁺) metal concentration. The photosynthetic apparatus (thylakoid membranes) were found to be the worst affected. Deteriorated or completely destroyed thylakoid membranes have made large empty spaces in the cell interior. In addition, at the highest concentration (8 mg/L Pb²⁺), the polyphosphate granules became more prominent both in size and number. Despite the initial slight stimulations (0.2, 3.8 and 6.5% respectively at 0.5, 1 and 2 mg/L Pb²⁺), both metals inhibited the growth in a dose-dependent manner as incubation progressed. Pigment contents (chlorophyll α, β carotene and phycocyanin) were also decreased with increasing metal concentration. Cells exposed to 6 mg/L Pb²⁺, resulted in 36.56, 37.39 and 29.34% reductions of chlorophyll α, β carotene and phycocyanin respectively over the control. Corresponding reductions for the same Cd²⁺concentrations were 57.83, 48.94 and 56.90%. Lethal concentration (96 h LC₅₀) values (3.47 mg/L Cd²⁺ and 12.11 mg/L Pb²⁺) indicated that Synechocystis sp. PCC 6803 is more vulnerable to Cd²⁺ than Pb²⁺. Supported by the Chinese Scholarship Council     

Steroids from green alga <Emphasis Type="Italic">Chaetomorpha basiretorsa</Emphasis> Setchell

Six steroids have been isolated from ethanolic extract of green alga Chaetomorpha basiretorsa Setchell by a combination of repeated normal phase silica gel and Sephadex LH-20 gel column chromatography as well as recrystallization. Using spectroscopic methods including MS and NMR, their structures were determined as β-1awsaritol （1）, saringosterol （2）, 24-hydroperoxy-24-vinyl- cholesterol （3）, β-stigmasterol （4）, stigmast-4-en-3α, 6β-diol （5）, 29-hydroxystigmasta-5, 24 （28）-dien-3β-ol （6）. All these compounds were obtained from this genus for the first time and they were inactive （IC50〉10μg/ml） against KB, Bel-7402, PC-3M, Ketr 3 and MCF-7 cell lines.     

Effect of lead on cytoskeletal protein stability in crucian carp <Emphasis Type="Italic">Carassius auratus</Emphasis>

Inorganic lead （Pb） is one of the most common environmental pollutants. Much evidence indicates that Pb exposure could directly affect fish growth and development. In this study, we investigated the cytotoxic effects of Pb on cytoskeletal protein stability at both protein and mRNA level in crucian carp Carassius auratus. Pb（NO3）2 treatment in concentration of 100 μmol/L resulted in decreased expression of both α- and β-tubulin but γ-tubulin as assayed with SDS-PAGE, Western Blot, and ELISA. In vivo and in vitro analyses on protein expression of tubulins are consistent. The effect of Pb on mRNA expression varied among different tissues. Our results suggest that cytotoxicity of Pb at protein translation level is stronger than at mRNA expression level.     

Chemical constituents of marine algal-derived endophytic fungus Exophiala oligosperma EN-21

Seven compounds (1–7) were identified from the cultivation of the endophytic fungus Exophiala oligosperma (EN-21) that was isolated from the inner tissue of the marine red alga Laurencia similis. Their structures were identified with spectroscopic and chemical methods as 2-phenoxynaphthalene (1), (2S, 3R, 4E, 8E)-1-O-β-D-glucopyranosyl-3-hydroxy-2-[(R)-2′-hydroxyoctadecanoyl] amino-9-methyl-4, 8-octadeca-diene (2), (22E,24R)-ergosta-7,22-dien-3β,5α,6β-triol (3), (22E, 24R)-3β, 5α, 9α-trihydroxy- ergosta-7, ...     

Cloning and analysis of phycoerythrin genes inGracilaria Lemaneiformis (Rhodophyceae)

Cloning and sequencing of the genes coding for the α- and β- subunit of phycoerythrin (PE) of a red alga—Gracilaria lemaneiformis (GL) are reported. Alignment of 1084 nucleotides sequenced with three known red algal PE genes,Rhodella violacea (RV),Polysiphonia boldii (PB) andAglaothamnion neglectum (AN), showed high level of conservation, and similarities of 77,6% (between GL and RV), 77.9% (GL and AN) and 79.0% (GL and PB). The similarities of amino acids were 84.8% (between GL and RV), 85.7% (GL and PB), and 80.6% (AN and GL), higher than those among nucleotides. Project 39670405 supported by NSFC and Japanese Science Promotion Society (JSPS).     

A comparative analysis of four kinds of polysaccharides purified from Furcellaria lumbricalis

Four kinds of polysaccharides (FA, FB, FC and FD) were extracted and purified from a red alga Furcellaria lumbricalis. Their monosaccharide composition, average molecular mass and structural feature were determined by gas chromatography (GC), high performance gel permeation chromatography (HPGPC) and Fourier transform infrared spectroscopy (FTIR), respectively. The results showed that FA and FB were composed of galactose (Gal), 3,6-anhydro-galactose (AnG) and 4-sulfated-galactose (G4S), which were structurally similar to β-carrageenan and κ-carrageenan. FC was composed of sulfated galactose and small amount of AnG, indicating that it was a hybrid-sulfated galactan. FD was composed of α-1,4-glucose and belonged to floridean starch. The respective yields of FA, FB, FC and FD were 4.84%, 33.74%, 8.76% and 13.5%, and the corresponding were 537 kD, 432 kD, 513 kD and 51 kD respectively. Owning to its high content (>60%) of polysaccharide, F. lumbricalis will be a good source of marine sulfated polysaccharide and shows its potential utilization in food and medicine.     

THE DYNAMIC EFFECTS OF A FINITE DEPTH AMBIENT FLUID ON BOTTOM EDDY

Scaling analysis shows that if o(ε~2, β_1ε, γε) ~o (δ), frontal geostrophic dynamics governs the behav-ior of an isolated bottom eddy in a finite depth ambient fluid; and that the ambient flow induced bybottom eddy migration satisfies quasi-geostrophic dynamics. This two layer model includes the impor-tant processes of advection of bottom eddy due to ambient flow, baroclinic instability, and form dragintroduced by Rossby waves. The numerical results show that the three processes enhance theinstability and alter the migration speed of the bottom eddy, and that the form drag induces asignificant meridional drift of the eddy.     

Immunotoxicity effect of benzo[α]pyrene on scallop Chlamys farreri

The toxic effects of benzo[α]pyrene (B[α]P) at different concentrations (0.1, 0.5, 1, 2.5 and 7.5 μgL⁻¹) on scallop (Chlamy farreri) immune system were studied. The results showed that B[α]P had significant toxic effects on the haemocyte counts, neutral red uptake, phagocytosis, bacteriolytic and antibacterial activity (P<0.05), while the seawater control and acetone control had no significant differences. The haemocyte counts, neutral red uptake, phagocytosis and bacteriolytic activity in all B[α]P treatment groups as well as antibacterial activity in groups of 0.5, 1, 2.5 and 7.5 μgL⁻¹ B[α]P decreased significantly (P<0.05). Some of these indices tended to be stable on the sixth day and others on the ninth day, and the indices showed clear time- and concentration-response to B[α]P. Bacteriolytic activity in 0.1μgL⁻¹ B[α]P treatment group and antibacterial activity in 0.1 μgL⁻¹ and 0.5 μgL- B[α]P treatment groups increased at the beginning of exposure and reached their peaks on day 1 and day 6, respectively. Following that, both activities decreased gradually and became stable after day 9. When all the indices reached stability, they were significantly lower than those in control group (P<0.05), except for antibacterial activity in 0.1 μgL⁻¹ B[α]P treatment group (P>0.05). Thus, B[α] has evident toxic effects on scallop immune system, which supports the view that a relationship exists between pollution and immunomodulation in aquatic organisms.     

Comparative studies on structural feature of agar polysaccharides fromPorphyra haitanensis grown in south and north China

The structural feature of agar polysaccharides fromPorphyra haitanensis grown in south China and transplanted to the north was investigated by fractionation on DEAE—Sephadex A 50, chemical analysis, and infrared and¹³C-NMR spectroscopy. The agars composed mainly of charged molecules were eluted from DEAE—Sephadex A 50 with 1.0 mol/L NaCl solution from the southernP. haitanensis and with 0.5 mol/L NaCl from the northern one. The¹³C-NMR spectra showed that agarobiose [(1→3)-β-D-galactopyranosyl-(1→4)-3,6-anhydro-α-L-galactopyranose] and the biological precursor of agarobiose [(1→3)-β-D-galactopyra nosyl-(1→4)-6-sulfate-α-L-galactopyranose] were the major disaccharide repeating units in the charged fractions. The content of the biological precursor in the agar polysaccharides from southernP. haitanensis was higher than that in the northern one, the content of the biological precursor extracted from cold water was higher than that from hot water, and the content of 6-OMe-D-galactose in the southernP. haitanensis polysaccharides was higher than in the northern one. This distinct difference will be of significance for further study of the physiological characters ofP. haitanensis. Contribution No. 1849 from the Institute of Oceanology, Academia Sinica.     

A new ketosteroid from red alga Acanthophora spicifera

A new ketosteroid, along with six known steroids, was isolated from the ethanolic extracts of red alga Acanthophora spicifera (Vahl.) Boergesen. The structures, identified using chemical and spectroscopic methods including 2D NMR, were: (1) 22-hydroxy-5α-cholest-3,6-dione, (2) 6-hydroxycholest-4-ene-3-one, (3) cholest-4-ene-3,6-dione, (4) cholest-5-ene-3β-ol, (5) 5α-cholestane-3,6-dione, (6) β-Sitosterol and (7) Saringosterol. The MTT method was used to test the cytotoxicity of the compounds against the human cancer cell lines, HCT-8, Bel-7402, BGC-823, A549 and HELA. Compounds 1, 2, 3 and 5 showed moderate cytotoxic activity against human cancer cell lines.     

Isolation and characterization of collagen from squid (Ommastrephes bartrami) skin

Collagen of squid (Ommastrephes bartrami) skin was examined in the present study. Histology showed that collagen fiber in the skin was partially cross-linked with muscle fiber. Acid-solubilized collagen (ASC) and pepsin-solubilized collagen (PSC) were extracted from the skin and characterized. The results of amino acid composition and electrophoretic patterns revealed that ASC and PSC were both type I collagen, containing α1 and α2 chains. FTIR (fourier transform infrared spectroscopy) investigations confirmed the existence of helical arrangements in PSC of squid skin. The denaturation temperature (T_d) and shrinkage temperature (T_s) of PSC were 29.4°C and 52.8°C, respectively.     

Effects of carboxymethyl-chitosan on wound healing in vivo and in vitro

Effects of carboxymethyl-chitosan with different molecular weights on wound healing were investigated in vivo and in vitro.A second degree burn model was performed in rats and the accelerative effects of carboxymethyl-chitosan on wound repair were observed.Contents of transforming growth factor(TGF)-β1,interleukin(IL)-6 and matrix metalloproteinase(MMP)-1 in wounds were determined by enzyme-linked immunosorbent assay(ELISA).In vitro study evaluated the influence of carboxy-methyl-chitosan on cytokines secretion of fibroblasts and macrophages.In vivo results showed that carboxymethyl-chitosan effec-tively accelerated the wound healing process in burned rats(P<0.05).Levels of TGF-β1,IL-6 and MMP-1 in carboxymethyl-chitosan groups were significantly elevated,compared with control group(P<0.05).In vitro results indicated that carboxymethyl-chitosan significantly promoted the proliferation of fibroblasts and stimulated its IL-8 and IL-10 secretion at different incubation time,but it did not affect collagen secretion of fibroblasts.Carboxymethyl-chitosan enhanced phagocytosis ability of macrophages,and in-creased its tumor necrosis factor(TNF)-α secretion.In conclusion,carboxymethyl-chitosan promoted wound healing by activating macrophages,accelerating fibroblasts growth and exerting considerable effects on the secretion of a series of cytokines.     

Bioaccumulation of Pb<Superscript>2+</Superscript> and its effects on growth,morphology and pigment contents of <Emphasis Type="Italic">Spirulina</Emphasis> (<Emphasis Type="Italic">Arthrospira</Emphasis>) <Emphasis Type="Italic">platensis</Emphasis>

A laboratory experiment was conducted to assess the bioaccumulation of Pb²⁺ and its effects on growth, morphology and pigment contents of Spirulina (Arthrospira) platensis. The specimen cultured in Zarrouk liquid medium was treated with various initial metal concentrations (0, 5, 10, 30, 50 and 100 μg mL⁻¹). The growth of S. platensis was adversely affected by Pb²⁺ at high concentrations (30, 50 and 100 μg mL⁻¹). However, at low concentrations (5 μg mL⁻¹), Pb²⁺ could stimulate its growth slightly. The pigment contents (chlorophyll α and β carotene) were decreased in a dose-dependent manner. The highest reductions (67% and 53% respectively in chlorophyll α and β carotene) were observed in 100 μg mL⁻¹ treatment group. The LC₅₀ (96 h) of Pb²⁺ was measured as 75.34 μg mL⁻¹. Apart from a few cases of filament breakages at elevated concentrations (50 and 100 μg mL⁻¹), morphological abnormalities are not specific. Metal bioaccumulation increased with Pb²⁺ concentrations, but decreased with exposure time. The maximum accumulated amount was 188 mg g⁻¹ dry weight. The bioconcentration factor (BCF) reached to a peak at day 2, followed by a gradual reduction for all the exposure concentrations. S. platensis is able to tolerate considerably high Pb²⁺ concentrations. Consequently it can be used as a potential species to remove heavy metal from contaminated waters.     

Effects of Mg2+, NaCl, citric acid, and other factors on synthesis and accumulation of β-carotene inDunaliella salina

The effect of Mg²⁺, NaCl and citric acid on the accumulation of β-carotene inDunaliella Salina was studied. The experimental results showed that 10.5 mmol/L Mg²⁺, 5 mol/L NaCl, 3 μmol/L citric acid, and CO₂ are favorable forDunaliella Salina cell growth and β-carotene accumulation. After 144 h culture under the above conditions, theDunaliella Salina biomass increased by 7.18 times; β-carotene reached 9.61%. Project 89023990 supported by the Shandong Natural Science Fund.     

Extraction of organochlorine pesticides in sediments using soxhlet,ultrasonic and accelerated solvent extraction techniques

The application of soxhlet, ultrasonic and accelerated solvent extraction techniques to the analysis of six organochlorine pesticides (α-HCH, β-HCH, γ-HCH, o, p'-DDT, p,p'-DDT and p, p'-DDE) in Taihu Lake sediment samples is described. It was found that the limits of quantification ranged from 0.002μgg-1 to 0.004μgg-1, and the recoveries of organochlorine pesticides with the three extraction techniques were acceptable (>80.7%). With a mass selective detector, better results were obtained by accelerated solvent extraction using hexane-acetone (1:1) as compared with soxhlet and ultrasonic extraction. It was shown that the accelerated solvent extraction was the optimum technique for the analysis of organochlorine pesticides in sediments. The general features of the three extraction techniques are also presented.     

SPECIES COMPOSITION, HORIZONTAL DISTRIBUTION AND SEASONAL SUCCESSION OF PHYTOPLANKTON IN THE CHANNEL FROM DONGTING LAKE TO THE CHANGJIANG RIVER, CHINA

The species composition, horizontal distribution and seasonal succession of the phyto-plankton at five sampling stations in the channel between Dongting Lake and the Changjiang River, China were studied from May 1995 to December 1997. A total of 416 taxa were observed; diatoms comprised the most diverse taxonomic group representing 58.2 % of the total species. The β-mezotrophic indicators were 92 taxa or 22 % of the total, the a-mezotrophic or α, β-eutrophic indicators decreased distinctly to 20 taxa or 4.8 % of the total. The species number and composition of various phyla were approximately similar at Stations 1, 2, 3 and 4, but at Station 5 the number of species was the minimum and the ratio of diatoms to total phytoplankton in the number of species was the highest. In seasonal succession of the phytoplank-ton species, the number was the highest in May and June, lower in December, January, March and July in the channel. The dominant species were different in different months. The ratio of diatoms species number to blue green algae and green algae species number diminished gradually from winter to summer and autumn, and then increased gradually from autumn to winter and early spring in the annual cycle. Margalef, Simpson and Shannon—Weaver diversity indices changed in different months, their values were higher in winter, lower in summer. Nygaard‘s diatoms quotients were lower in winter, then in spring and autumn, higher in summer. These results indicated that the water quality was the best in winter, better in spring and autumn than in summer. The relationship between the structure of the phytoplankton communi-ty and the water environmental quality was discussed.     

ANNUAL CHANGES IN PLASMA LEVELS OF CORTISOL AND SEX STEROID HORMONES IN MALE RAINBOW TROUT, ONCORHYNCHUS MYKISS

The profiles of cortisol, testosterone, ll-ketotestosterone and 17α， 20β- dihydroxy-4-pregnene-3-one in mule rainbow trout reared under constant water temperature and natural photoperiod were determined by radioimmunoassay. Gonads of male rainbow trout reached maturity when the fish were two years old. Changes in the plasma levels of both sex steroid hormones and cortisol were closely related to the GSI. Plasma levels of testosterone, 11-ketotestostemne and 17a, 2013-dihydroxy 4-pregnene-3-one showed a clear peak in the annual breeding season, when the GSI reached their maxima. Plasma cortisol levels also showed clearly seasonal changes in both two- and three-year-old fish. The results suggest that the elevated plasma levels of cortisol may not just be due to stresses during the breeding season but have certain physiological functions in the reproduction of rainbow trout.     

Chemical constituents of marine medicinal mangrove plant <Emphasis Type="Italic">Sonneratia caseolaris</Emphasis>

Twenty-four compounds including eight steroids (1–8), nine triterpenoids (9–16, 24), three flavonoids (20–22), and four benzenecarboxylic derivatives (17–19, 23) were isolated and identified from stems and twigs of medicinal mangrove plant Sonneratia caseolaris. The structures of the isolated compounds were determined by extensive analysis of their spectroscopic data. Among these metabolites, compounds 1, 4–20 and 22–24 were isolated and identified for the first time from S. caseolaris. In the in vitro cytotoxic assay against SMMC-7721 human hepatoma cells, compound 21 (3′,4′,5,7-tetrahydroxyflavone) exhibited significant activity with IC₅₀ 2.8 μg/mL, while oleanolic acid (14), 3,3′-di-O-methyl ether ellagic acid (18), and 3,3′,4-O-tri-O-methyl ether ellagic acid (19) showed weak activity. None of these compounds displayed significant antibacterial activites. Supported by the National Natural Science Foundation of China (No. 30770234); Knowledge Innovation Program of Chinese Academy of Sciences (KZCX2-YW-211-04); Department of Science and Technology of Shandong Province (No.2006GG2205023)