The changes of three components in coelomic fluid of Urechis unicinctus exposed to different concentrations of sulfide

The changes in heme (associated with hemoglobin), hemoglobin and hematin in the coelomic fluid of marine worm,Urechis unicinctus, exposed to different concentrations of sulfide, were investigated using biochemical techniques. When exposed to different sulfide concentrations for up to 96 h, the relative amounts of the three components changed in a regular pattern suggesting that the coelomocytes play an important role in the worm's tolerance to sulfide. The possible roles of heme compounds in sulfide tolerance of this species are discussed on the basis of our experimental data. This research was supported by the NSFC-KOSEF scientific cooperation program and NSFC (No. 30271039)     

The effect of toxic sulfide exposure on oxygen consumption and oxidation products in Urechis unicinctus (Echiura: Urechidae)

To investigate sulfide detoxification in Urechis unicinctus,oxygen consumption rate and sulfide detoxification productswere analyzed during sulfide exposure under controlled laboratory conditions.The results showed that oxygen consumption rateswere elevated significantly during 3 h sulfide exposure compared to the control(P0.05).The concentration of sulfite in body walland hindgut of experimental worms increased significantly(P0.05)when exposed to 50μmolL-1sulfide,reached a maximum at24 h and then decreased.Similar result was observed in worms exposed to 150μmolL-1sulfide except that sulfite concentrationreached a maximum at 12 h.Contents of thiosulfate in body wall and hindgut of U.unicinctus exposed to sulfide were also significantly higher than that of the control without sulfide exposure.In conclusion,during short-time sulfide exposure U.unicinctus mayraise oxygen consumption to detoxify toxic sulfide into sulfite and thiosulfate.Sulfide detoxification was restrained when the expo-sure time was prolonged or sulfide concentration was increased,which was indicated by decrease of sulfite,the intermediate productof sulfide detoxification.     

Effects of <Emphasis Type="Italic">Urechis unicinctus</Emphasis> juveniles on chemical characteristics of organically contaminated coastal sediment

Biological activities of marine benthos such as burrowing and feeding may change sediment characteristics. We conducted three experiments to examine the potential of using juveniles of a spoon worm Urechis unicinctus to improve the quality of organically contaminated coastal sediment. Sediment samples were collected from a site that was heavily contaminated with organic matter (Seonso) and two sites that were clean (Myo-do, Dolsan-do). Urechis juveniles, obtained by artificial fertilization and cultured in the laboratory, were introduced to the sediment (weight 3 kg, depth 10 cm) at a density of 500 individuals per aquarium (length 50 cm, width 35 cm, height 30 cm) (Experiment 1), or at densities ranging from 100 to 900 individuals per beaker (Experiment 2). To examine how sediment contamination can be modified by the effects of Urechis, 500 individuals (per aquarium) were exposed to the Seonso contaminated sediment that had been mixed with 0–100% clean sand (Experiment 3). Each experiment lasted two months and sediment samples were collected every 15 d to determine the several indexes of sediment quality, which included acid volatile sulfide (AVS), chemical oxygen demand (COD) and total ignition loss (TIL). In Experiment 1, the existence of Urechis did not result in significant changes in quality indexes in the sediments collected from Myo-do, Dolsan-do. However, AVS, COD and TIL of the Seonso sediment all decreased significantly after co-incubation with Urechis juveniles for 30 to 45 d. Experiment 2 showed that a density of at least 300 juveniles per beaker was necessary to significantly reduce all three quality indexes, and the magnitude of reduction was positively correlated with juvenile density. Experiment 3 revealed that Urechis juveniles were effective in reducing the AVS, COD and TIL of the Seonso sediment that had been mixed with 60%, 80%, and 80% of clean sand, respectively. The results of the present study therefore indicated that juveniles of this spoon worm have the potential to be used to improve the quality of organically contaminated sediment in coastal waters.     

Studies on the Tolerating Mechanism for Sulfide in Urechis Unicinctus (Echiura:Urechidae)-cytological observation on Urechis Unicinctus in Different Hydrogen Sulfide Environment

This study on the cytological changes of the body wall ,aspiratory intestine and crissal bursa in Urechis unicincuts by light microscope(LM) and transmission electron microscope(TEM) showed that the difference between the body wall and the natural environment rich in H2S was not obvious,that the wall color of the aspiratory intestine in H2S rich environment changed from normal semitransparency to dark brown.that its epithelia were disassembled and the electron density of its cytoplasm matrix was lower;and that in H2S rich environment many basoplhilic granules occurred in the epithelia of the crissal bursa.Granules with single membrane and myelinefingure were found with TEM.     

The adaptability of three Arctic microalgae to different low temperatures

In order to study the adaptability of Arctic mieroalgae to different environmental temperatures, the growth curves and antioxidase system of three microalgae ( Skeletonema marinoi, Chlorella sp. and Chlam ydomonas sp. ) that were separated from the Ny-Alesund, the high Arctic, at different low temperatures (0 ℃, 4 ℃ and 8 ℃ ) were determined. The result showed that the adaptability of the microalgae to temperatures depended on the species. The growth rate, SOD and CAT activities of Skeletonema marinoi were the highest at 4 ℃,but MDA content was the lowest. The growth rate and enzyme activity of Chlorella sp. were the highest at 8 ℃, while the lowest MDA content presented at 0 ℃. The growth of Chlamydomonas sp. at the different temperatures was not so significant, the lowest MDA content presented at 8 ℃. The change of antioxidase system also depended on species and temperatures. Three indexes of antioxidase system of Skeletonema marinoi between 0 ℃ and 4 ℃ showed extremely significant difference (p < 0. 01 ). SOD activity of Skeletonema marinoi and Chlorella sp. between 0 ℃ and 8 ℃ showed significant difference (p<0.05),and the other two indexes of them differed insignificantly. Antioxidase systems of Chlamydomonas sp. at the three temperatures differed insignificantly. In conclusion, the three microalgae had good adaptability to the three temperatures;their MDA content presented a low level, and had unique physiological mechanism to adapt to the environment with different low temperatures.     

Biochemical response of the mussel Mytilus coruscus (Mytiloida: Mytilidae) exposed to in vivo sub-lethal copper concentrations

Many aquatic organisms are negatively affected by exposure to high copper concentrations.We investigated the biochemical response of the mussel Mytilus coruscus(Mytiloida:Mytilidae) to copper exposure.In vivo bioassays using M.coruscus and different copper concentrations were conducted.The activity of six biomarkers,namely superoxide dismutase(SOD),catalase(CAT),acid phosphatase(ACP),alkaline phosphatase(AKP),glutamic-oxaloacetic transaminase(GOT) and glutamic-pyruvic transaminase(GPT) were measured.Survival rates decreased with increased copper concentrations and exposure times.The LC50 values at 48,72,and 96 h exposure were 0.48,0.37,and 0.32 mg/L,respectively.Within digestive glands,CAT activity increased with increasing Cu concentrations.The activity of AKP showed no significant change,while the remaining four enzymes showed decreasing activity with increasing Cu concentrations.Within the gills,AKP activity increased when the Cu concentration was 0.05 mg/L,but showed no significant changes at higher concentrations.Activity of CAT and ACP within gills tended to decrease with increasing Cu concentration.The activity of SOD and GPT decreased at an exposure concentration of 0.2 mg/L.GOT activity within gills decreased at 0.1 mg/L and increased at an exposure concentration of 0.2 mg/L.Within the adductor muscle,AKP activity increased at 0.05 mg/L but did not change at higher exposure concentrations.ACP activity within adductor muscle tissue showed no change,while activities of CAT,GOT and GPT decreased with increasing Cu concentrations.SOD activity within the adductor muscle tissue significantly decreased at the 0.02,0.05 and 0.2 mg/L exposure concentrations.Our results show tissue specific differences for the six biomarkers in for M.coruscus.Our findings provide the basis for the establishment of reference activity levels against which biomarker changes can be estimated,and are essential preliminary steps in development of in vivo bioassays.     

Variations in retention efficiency of bivalves to different concentrations and organic content of suspended particles

Retention efficiencies (RE) of scallop (Chlamys farreri),oyster (Crassostrea gigas) and mussel (Mytilus edulis) in a flow-through system were measured to understand the short-term response to various particle and organic matter concentrations.By comparing the RE of C.farreri with that of C.gigas and M.edulis,we gained further knowledge on the feeding physiological characteristics of C.farreri and ascertained the possible cause of high summer mortalities of this species.The experimental feeding conditions in...     

Expression profiles of two small heat shock proteins and antioxidant enzyme activity in Mytilus galloprovincialis exposed to cadmium at environmentally relevant concentrations

Small heat shock proteins encompass a widespread but diverse class of proteins,which play key roles in protecting organisms from various stressors.In the present study,the full-length cDNAs of two small heat shock proteins(MgsHSP22 and MgsHSP24.1)were cloned from Mytilus galloprovincialis,which encoded peptides of 181 and 247 amino acids,respectively.Both MgsHSP22 and MgsHSP24.1 were detected in all tissues examined by real-time PCR,with the highest expression being observed in muscle and gonad tissues.The real-time PCR results revealed that Cd signifi cantly inhibited MgsHSP22 expression at 24 h and MgsHSP24.1 at 24 and 48 h under 5 μg/L Cd 2 + exposure.MgsHSP24.1 expression was also signifi cantly inhibited after 50 μg/L Cd 2+ exposure for 48 h.With regard to antioxidant enzymes,increased GPx and CAT activity were detected under Cd 2+ stress(5 and 50 μg/L),while no signifi cant difference in SOD activity was observed throughout the experiment.Overall,both MgsHsps and antioxidant enzymes revealed their potential as Cd stress biomarkers in M.galloprovincialis.     

Responses in growth, lipid accumulation, and fatty acid composition of four oleaginous microalgae to different nitrogen sources and concentrations

Nitrogen deficiency is an effective strategy for enhancing lipid production in microalgae. Close relationships exist among lipid production, microalgal species, and nitrogen sources. We report growth, lipid accumulation, and fatty acid composition in four microalgae （Chloroeoccum ellipsoideum UTEX972, Chlorococcum nivale LB2225, Chlorococcum tatrense UTEX2227, and Scenedesmus deserticola JNU19） under nitrate- and urea-nitrogen deficiencies. We found three patterns of response to nitrogen deficiency： Type-A （decrease in biomass and increase in lipid content）, Type-B （reduction in both biomass and lipid content）, and Type-C （enhancement of both biomass and lipid content）. Type-C microalgae are potential candidates for large-scale oil production. Chlorococcum ellipsoideum, for example, exhibited a neutral lipid production of up to 239.6 mg/（L＇d） under urea-nitrogen deficiency. In addition, nitrogen deficiency showed only a slight influence on lipid fractions and fatty acid composition. Our study provides useful information for further screening hyper-lipid microalgal strains for biofuel production.     

THE COLD AND HOT DAMAGES TO THE CITRUS IN THE THREE GORGES AREA OF THE CHANGJIANG RIVER

ＴＨＥＣＯＬＤＡＮＤＨＯＴＤＡＭＡＧＥＳＴＯＴＨＥＣＩＴＲＵＳＩＮＴＨＥＴＨＲＥＥＧＯＲＧＥＳＡＲＥＡＯＦＴＨＥＣＨＡＮＧＪＩＡＮＧＲＩＶＥＲＣｈｅｎＺｈｅｎｇｈｏｎｇ（陈正洪）；ＹａｎｇＨｏｎｇｑｉｎｇ（杨红青）；ＮｉＧｕｏｇｕ（倪国裕）（Ａｇｒｏ...