Evaluation of Reference Genes for Quantitative Real-Time PCR Analysis in Manila Clam Ruditapes philippinarum Under Hypoxic Stress

Quantitative real-time PCR(qRT-PCR)has been widely used for gene expression analysis,and selection of reference genes is a key point to obtain accurate results.To find out optimal reference genes for qRT-PCR in Manila clam Ruditapes philippinarum in response to hypoxia,different tissues were used and compared to evaluate the stability of candidate reference genes under low oxygen stress(DO 0.5mgL^(−1) and DO 2.0mgL^(−1))and normal condition(DO 7.5mgL^(−1)).Seven candidate reference genes were selected to evaluate the stability of their expression levels.The reference genes were evaluated by Delta Ct,BestKeeper,NormFinder and geNorm,and then screened by RefFinder calculation.Under hypoxic stress of 0.5mgL^(−1),the most suitable reference gene for gill and hepatopancreas was RPL31,and the optimal reference genes for axe foot and adductor muscle were TUB and HIS,respectively.For hypoxic stress of 2.0mgL^(−1),the most stable reference gene for gill and hepatopancreas was RPL31,and the optimal reference genes for axe foot and adductor muscle were RPS23 and EF1A,respectively.At the normal condition,HIS and EF1A were identified as the optimal internal reference genes in gill and hepatopancreas respectively,and GFRP2 was the best internal reference gene for axe foot and adductor muscle.The present findings will provide important basis for the selection of reference genes for qRT-PCR analysis of gene expression level in bivalves under hypoxic stress,which might be helpful for the analysis of other molluscs too.

坡口形状对CLAM钢焊缝抗辐照损伤性能的影响

为探究坡口形状对中国低活化马氏体(CLAM)钢焊缝辐照损伤性能及辐照硬化性能的影响,采用扫描电子显微镜(SEM)、原子力显微镜(AFM)、透射电子显微镜(TEM)、掠入射X射线衍射(GIXRD)和纳米压痕技术等方法,研究了在室温下经能量为70 keV、剂量为1×10^(17)ions/cm^(2)的He^(+)辐照后,V型、U型和双U型坡口CLAM钢焊缝的辐照损伤情况及力学性能。结果表明,离子辐照后,不同坡口形状焊缝金属中均产生了氦泡、析出物等缺陷,力学性能呈现出不同程度的降低。与V型和U型坡口焊缝相比,双U型坡口焊缝辐照后焊缝内部缺陷分布更均匀、尺寸更小。这是由于在三类焊缝中,双U型坡口焊缝热输入更小,焊缝晶粒组织相对较小,晶界密度更高。更高密度的晶界阻碍了缺陷间的相互聚集,减小了缺陷的尺寸。辐照后双U型坡口焊缝表面粗糙度最低,氦泡、析出物尺寸最小,衍射峰偏移量、宽化率最低,表面硬度最低,抗辐照硬化性能最好。这表明通过控制焊接坡口的形状,细化焊缝晶粒组织,可显著提升焊缝抗辐照损伤性能及抗辐照硬化性能。

高能氦离子辐照对CLAM钢微观结构和力学行为的影响

聚变堆包层结构材料在服役期间会产生辐照损伤,CLAM钢作为热核聚变堆的首选结构材料,对其进行辐照行为研究十分有必要。采用高能氦离子对CLAM钢进行辐照实验,利用纳米压痕实验结合原子力显微镜(AFM)研究CLAM钢在辐照过程中的微观组织演化和力学性能的变化。结果表明:辐照后的CLAM钢中形成位错环和He泡,且随着辐照剂量的增加,位错环和He泡密度增加,尺寸增大。辐照后CLAM钢发生显著的辐照硬化效应,随着辐照剂量的增加,辐照硬化程度增加,但当辐照剂量增大到一定程度,辐照硬化效应减弱。利用DBH模型和FKH模型讨论辐照中微观结构的变化对辐照硬化效应的影响。随着辐照剂量的增加,压痕周围材料隆起堆积的范围减小,堆积高度增加,且高剂量辐照后压痕周围的堆积中出现了剪切带,表明CLAM钢辐照后脆性明显增加。

Physiological Responses of Clam(Ruditapes philippinarum)to Transport Modes with Different Temperatures

Given the increased circulation time after fishing,a series of changes take place in live clams,leading to a deterioration in quality even after death.Thus,in this study,we aimed to explore the optimal mode of transportation of clams.The container for holding clams was reformed,and a water circulation temperature control system was established.The physiological responses of clams during anhydrous and watery transportation at two temperatures(4 and 15℃)were investigated based on the aforementioned system.When comparing the transportation patterns after 3 d of transport,a higher survival rate was observed at 4℃(97%)than at 15℃(63%)in the anhydrous transportation groups and a lower survival rate was observed at 4℃(93%)than at 15℃(99%)in the watery transportation groups.In addition,the glycogen content,condition index(CI),and adenylate energy charge(A.E.C)value were higher at4℃((40.87±0.99)mg g^(-1),13.71%±0.50%and 57.45%±1.60%)than at 15℃((30.54±0.81)mg g^(-1),9.09%±0.30%and 43.12%±1.65%)in the anhydrous transportation groups.In the watery transportation groups,a lower glycogen content,CI,and A.E.C.value were observed at 4℃((33.78±0.84)mg g^(-1),9.78%±0.50%and 64.65%±1.25%)than at 15℃((41.53±0.93)mg g^(-1),12.72%±0.83%and 71.58%±1.27%).Results from this study show that anhydrous transportation(4℃)is the optimal transport condition for clams to maintain a high quality and good physiological conditions.Thus,this study will be particularly useful for establishing shellfish transportation systems.

pH胁迫对菲律宾蛤仔(Ruditapes philippinarum)耗氧率、排氨率、免疫和抗氧化酶活性以及组织形态的影响

随着人类工业迅速发展,CO_(2)大量排放,引起了海洋的酸化效应,不仅导致了全球气候变暖,也严重危害了海洋生物的生态健康。以菲律宾蛤仔(Ruditapes philippinarum)为研究对象,研究pH变化对菲律宾蛤仔耗氧率、排氨率、鳃组织结构以及鳃和内脏团的免疫、抗氧化酶活性的影响。将菲律宾蛤仔置于酸化海水(pH 6.4、7.1和7.7)中,以自然海水(pH 8.1)为对照。结果表明:耗氧率和排氨率随着pH的升高或降低而降低,在pH=8时达到最大值;6.4酸化组蛤仔鳃组织结构损伤严重,鳃丝间距扩大,纤毛黏合;鳃组织碱性磷酸酶(AKP)第42天所有酸化组活性显著高于对照组(P<0.05),所有酸化组溶菌酶(LZM)和酸性磷酸酶(ACP)活性显著低于对照组(P<0.05),7.7酸化组超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GSH-Px)活性和总抗氧化能力(T-AOC)显著高于对照组(P<0.05),所有酸化组丙二醛(MDA)含量显著低于对照组(P<0.05);内脏团7.1和7.7酸化组LZM活性显著高于对照组(P<0.05),所有酸化组T-AOC和SOD活性显著高于对照组(P<0.05),7.1和7.7酸化组MDA含量显著低于对照组(P<0.05)。酸化致使菲律宾蛤仔耗氧率和排氨率降低,减缓其生理活动,降低鳃组织的免疫和抗氧化酶活性,打破蛤仔原有的代谢水平,会增加蛤仔患病的可能性。

AFLP analysis revealed differences in genetic diversity of four natural populations of Manila clam (Ruditapes philippinarum) in China

The amplified fragment length polymorphism （AFLP） technology was used to analyze the genetic diversities in four natural populations of Manila clam （ Ruditapes philippinarum）, distributed in four sea areas of China, i.e. , the Bohai Sea, the Huanghai Sea, the East China Sea and the South China Sea. Two hundred and sixty-four AFLP loci were analysed in 195 individuals and revealed high levels of genetic diversity. The percentage of polymorphic loci ranged from 92.13% to 96.06% and the Shannon＇ s information index was from 0.256 8 to 0. 275 6. By analyzing molecular variance （ AMOVA）, it was found that there were high levels of genetic differentiation between populations of Qingdao and the other three sea areas. Cluster analysis by Nei＇ s pairwise distances grouped specimens by geographical origin, except the population of Qingdao. A conclusion can be drawn that there are high genetic diversities in the four natural populations of Manila clam in China and some distinct differences existed among and between the four populations. The results also indicated that human cultivation activities will have great influence on the genetic structure of the population of Qingdao.

Inbreeding Depression on Growth and Survival of Full-Sib Family of Manila Clam(Ruditapes philippinarum)

In present study, the inbreeding depression(ID) of growth and survival of Manila clam(Ruditapes philippinarum) was investigated at larval and juvenile stages. Nine inbred families(A_2, B_2, C_2, D_2, E_2, F_2, G_2, H_2 and I_2) were established by mating within nine full-sib families with expected inbreeding coefficient of 0.25. Inbred families showed significant differences in shell length and hatching rate of D-larvae(straight-hinged larvae). The larvae of the nine inbred families grew slower than those of control group(CG), and their ID value ranged from 0.81% ± 6.09% to 16.10% ± 1.49%. The ID value of larval survival rate varied between 27.47% ± 9.36% and 70.50% ± 13.66%. The ID was also detected for juvenile growth in A_2, B_2, C_2, and D_2, which ranged from 4.60 ± 2.21 to 17.71 ± 7.73. The A_2 family maintained the highest juvenile survival rate, whereas the other inbred families exhibited ID values varying between 62.79% ± 4.54% and 96.14% ± 0.87%. The linear relationship of estimated ID between growth and survival was negatively correlated(R =-0.434, P < 0.05). The results of this study suggested that the ID of growth was common at the larval stage but was less prevalent at juvenile stage. In contrast, the ID of survival increased from larval to juvenile stage. A better understanding of the effect of inbreeding may aid to selective breeding of Manila clam.

Identification of Perkinsus-like parasite in Manila clam, Ruditapes philippinarum using DNA molecular marker at ITS region

Genomic DNA was extracted from hypnospores of Perkinsus-like parasite of Manila clam Ruditapes philippinarum collected at the fishing grounds in Huanghai Sea coast Shicheng Island and East China Sea coast Ningbo, China. The internal transcribed spacer（ITS） in rDNA was PCR-amplified, cloned, sequenced, and compared with that of five Perkinsus species in GenBank. The fragment amplified from DNA of parasite of either Shicheng Island or Ningbo contained 649 bp, including partial ssrRNA（51 bp） and ITS（＋5.8 S） （598 bp） regions. The ITS（＋5.SS） sequences of Perkinsus-like parasite of both Shicheng Island and Ningbo were all 99% identical to those ofPerkinsis atlanticus, and were not more than 95% identical to those of other four Perkinsus species including P. marinus, P. andrewsi, P. qugwadi and P. medierraneus.The ITS （＋5.8S） sequence of Perkinsus-like parasite of Shicheng Island was 99% identical to that of Ningbo. These facts about nucleotide sequences suggested that the Perkinsus-like parasite in Manila clam, Ruditapes philippinarum collected from either the Huanghai Sea coast or the East China Sea coast was P. atlanticus, and might reflect P. atlanticus strains of distinct geographic distribution.

Mass Selection for Fast Growth in the Third Generation of the Orange Line of the Manila Clam Ruditapes philippinarum

The Manila clam Ruditapes philippinarum is natively distributed along the Pacific coast of Asia,where it is one of the most important bivalve species for local fisheries.This species has been intentionally introduced due to its high adaptability to various coastal environments and is currently widely cultivated in Europe and North America.We have initiated a selective breeding program to improve the growth rate of the Manila clam since 2007,and a full-sib family with orange shell color was selected.This family features high survival but slow growth.Thereafter,two generations of mass selection were conducted in this family by 10% upward selection for faster growth.In 2011,three types of lines were produced by selecting the breeder from the second-generation of selected lines.These lines are SS(subject to three generations of selection for growth in shell length),SC(selected for the second but not the third generation),and C(randomly sampled individuals from the national population).The genetic parameters of the shell length including hR^2(realized heritability),SR(selection response),and GG(genetic gain)were analyzed.Results showed that the shell length of the SS line was significantly larger than those of the SC and C lines at all developmental stages(P<0.05).For the larval stage,the values of hR^2,SR,and GG were 0.42,0.73,and 6.66,respectively.For the juvenile stage,the values of hR^2,SR,and GG were 0.40,0.69,21.76,respectively.For grow-out stage,the values of hR^2,SR,and GG were 0.48,0.83,and 18.22,respectively.The results of hR^2 indicated the good potential of the SS line in selective breeding.The level of GG improvement was encouraging and consistent with the previous expectations.No inbreeding depressions in the shell length were observed in the SS and SC lines at all sampling days.All of the results indicate that maintaining selection pressure in successive generations may be effective in the selective breeding program of this family.

Accumulation of petroleum hydrocarbons and heavy metals in clams (Ruditapes philippinarum) in Jiaozhou Bay,China

Accumulation and distributions of aliphatic and polyaromatic hydrocarbons (PAHs) and heavy metals were measured in tissues of the clam Ruditapes philippinarum collected from 5 sites in Jiaozhou Bay,Qingdao,China.The concentrations of total aliphatic hydrocarbon and PAHs ranged from 570 to 2 574 ng/gdw (gram dry weight) and from 276 to 939 ng/gdw,in the most and least polluted sites,respectively.The bio-accumulation of hydrocarbons and PAHs in the clams appeared to be selective.Aliphatic hydrocarbons were predominantly represented by short chain (<nC23) n-alkanes,suggesting that petroleum hydrocarbons were likely the major contamination source.The selective uptake of 3 and 4 ring PAHs,such as naphthalene,fluorene,phenanthrene,fluoranthene and pyrene,by the clams was probably related to the physiological and bio-kinetic processes that were energetically favorable for uptake of compounds with fewer rings.Accumulation of the metals Cd,Cu,Zn,Pb,Cr,Hg,and As in the clam tissues also showed high variability,ranging from 0.043 to 87 μg/gdw.Among the 7 detected metals,Zn,Cd,Cu,and As had a particularly high potential of accumulation in R.philippinarum.In general,a positive correlation was found between the tissue concentrations and sediment concentrations of hydrocarbons and of some metals.Our study suggests that moderate contamination with polyaromatic hydrocarbons,and low to moderate contamination with metals,currently exists for clam R.philippinarum in Jiaozhou Bay,in comparison with other regional studies.A long-term monitoring program is certainly needed for assessment of the potential ecological influence and toxicity of these contaminants of R.philippinarum in Jiaozhou Bay.

Impact of seawater acidification on shell property of the Manila clam Ruditapes philippinarum grown within and without sediment

Although the impact of ocean acidification on marine bivalves has been previously investigated under mainly controlled laboratory conditions,it is still unclear whether the impact of acidification on sediment-burrowing species differs between those within or without sediment.In order to fill this gap in our knowledge,we compared shell properties of the infaunal Manila clam(Ruditapes philippinarum)exposed to three pH concentrations(7.4,7.7,and 8.0),within and without sediments.In the first experiment(140 d),clams were exposed to seawater in an acidification system without sediment.A decrease in shell weight corresponding to the increase in dissolution rate was observed in the group ofpH 7.4,at which shell color disappeared or whitened.SEM observations confirmed the changes of the external shell surface.In the second experiment(170 d),sediment was placed at the bottom of each exposure chamber.The effects were found obvious in shell dissolution rate and shell color in the shell specimens exposed to overlying seawater but not found in the shell specimens exposed to sediment.Although the experimental period was longer in the second experiment,shell specimens in the first experiment were more seriously damaged than those in the second experiment under acidic seawater conditions.Our results,in relation to the defense function of the shell,show that marine bivalves in burrowing behavior are more adaptable to seawater acidification than those who do not burrow into sediment.

合金碳化物M_(23)C_(6)对CLAM钢晶界拉伸性能的影响机理研究

低活化马氏体-铁素体钢是目前核聚变反应堆的首选结构材料之一,钢中纳米级碳化物析出相对其韧塑性能起关键作用。本文以CLAM钢为研究对象,利用SEM、TEM对其显微组织、碳化物析出相M23C6(M=Fe,Cr)相及断裂微区进行表征与分析。结果表明,M_(23)C_(6)主要分布在马氏体板条边界,在拉伸过程中会造成位错缠结堆积,促发微裂纹的萌生和扩展。为了从原子尺度上探究碳化物对晶界变形行为的影响,采用分子动力学方法模拟了拉伸变形过程中晶界(∑5(031))上碳化物和位错的交互作用。模拟结果显示,晶界的塑性变形以位错滑移和非晶化塑性变形为主。随着碳化物尺寸增大和数量增多,非晶化塑性变形程度增强,位错运动受阻,造成局部结构应力集中并产生微裂纹。

The influence of salinity on toxicological effects of arsenic in digestive gland of clam Ruditapes philippinarum using metabolomics

Ruditapes philippinarum,a clam that thrives in intertidal zones of various salinities,is a useful biomonitor to marine contaminants.We investigated the influence of dilution to 75% and 50% of normal seawater salinity(31.1) on the responses of the digestive gland of R.philippinarum to arsenic exposure(20 μg/L),using nuclear magnetic resonance(NMR)-based metabolomics.After acute arsenic exposure for 48 h,salinity-dependent differential metabolic responses were detected.In normal seawater,arsenic exposure increased the concentrations of branched-chain amino acids,and of threonine,proline,phosphocholine and adenosine,and it decreased the levels of alanine,hypotaurine,glucose,glycogen and ATP in the digestive glands.Differential changes in metabolic biomarkers observed at lower salinity(～23.3) included elevation of succinate,taurine and ATP,and depletion of branched-chain amino acids,threonine and glutamine.Unique effects of arsenic at the lowest salinity(～15.6) included down-regulation of glutamate,succinate and ADP,and up-regulation of phosphocholine.We conclude that salinity influences the metabolic responses of this clam to arsenic.

Use of antioxidant enzymes of clam Ruditapesphilippinarum as biomarker to polycyclic aromatic hydrocarbon pollution

The typical organic pollutant polycyclic aromatic hydrocarbon(PAH) anthracene was selected as a contaminant to investigate its eff ects on the activities of superoxide dismutase(SOD), catalase(CAT) and glutathione peroxidase(GSH-Px) in the clam Ruditapes philippinarum. The results show that SOD, CAT and GSH-Px had diff erent induction and inhibition reactions to anthracene stress, and that three diff erent organs in R. philippinarum(visceral mass, muscle tissue and mantle) had diff erent sensitivities to anthracene stress. This study suggest that SOD activities of the visceral mass, CAT activitities of the mantle and the visceral mass, and GSH-Px activity of the muscle tissue could be used as sensitive indicators of anthracene stress in R. philippinarum.

CLAM钢表面Fe-Al/Al_(2)O_(3)涂层的制备及其耐腐蚀性能研究

采用热浸镀及热扩散工艺在中国低活化马氏体钢(CLAM)表面制备出一层FeAl合金层,通过氧化处理成功地在CLAM表面制备出一层致密的氧化涂层。利用高分辨透射电镜分析了表面生长的氧化层为单一的氧化铝涂层。利用场发射扫描电镜(FESEM)及能量散射谱仪(EDS)分析了不同氧化工艺对于涂层结构及组成的影响。通过电化学阻抗谱测试分析不同氧化条件下制备的样品的耐腐蚀性能。结果表明,750℃下氧化4 h制备的涂层耐腐蚀性能最佳,其极化电阻值为8 059.54Ω·cm^(2),有效孔隙率为0.142 87。

Annual Variations of Biogenic Element Contents of Manila Clam(Ruditapes philippinarum) Bottom-Cultivated in Jiaozhou Bay, China

Manila clam(Ruditapes philippinarum) was monthly sampled from its benthic aquaculture area in Jiaozhou Bay from May 2009 to June 2010. The annual variations of major elemental composition, organic content, fatness and element ratio of Manila clam were examined. The element removal effect of clam farming in Jiaozhou Bay was analyzed based on natural mortality and clam harvest. The results indicated that the variation trend of carbon content in shell(Cshell) was similar to that in clam(Cclam). Such a variation was higher in summer and autumn than in other seasons, which ranged from 9.10 ± 0.13 to 10.38 ± 0.09 mmol g-1 and from 11.28 ± 0.29 to 12.36 ± 0.06 mmol g-1, respectively. Carbon content of flesh(Cflesh) showed an opposite variation trend to that of shell in most months, varying from 29.42 ± 0.05 to 33.64 ± 0.62 mmol g-1. Nitrogen content of shell(Nshell) and flesh(Nflesh) changed seasonally, which was relatively low in spring and summer. Nshell and Nflesh varied from 0.07 ± 0.009 to 0.14 ± 0.009 mmol g-1 and from 5.46 ± 0.12 to 7.39 ± 0.43 mmol g-1, respectively. Total nitrogen content of clam ranged from 0.50 ± 0.003 to 0.76 ± 0.10 mmol g-1 with a falling tend except for a high value in March 2010. Phosphorus content of clam(Nclam) fluctuated largely, while phosphorus content of shell(Pshell) was less varied than that of flesh(Pflesh). Pshell varied from 0.006 ± 0.001 to 0.016 ± 0.001 mmol g-1; while Pflesh fluctuated between 0.058 ± 0.017 and 0.293 ± 0.029 mmol g-1. Pclam ranged from 0.015 ± 0.002 to 0.041 ± 0.006 mmol g-1. Carbon and nitrogen content were slightly affected by shell length, width or height. Elemental contents were closely related to the reproduction cycle. The removal amounts of carbon, nitrogen and phosphorus from clam harvest and natural death in Jiaozhou Bay were 2.92×104 t, 1420 t and 145 t, respectively. The nutrient removal may aid to reduce the concentrations of nitrogen and phosphorus, the main causes of eutrophication, and to maintain the ecosystem health of Jiaozhou Bay.

Seawater acidification affects the immune enzyme activities of the Manila clam Ruditapes philippinarum

Ocean acidification leads to changes in physiological and immune responses of bivalves, but the eff ect on the immune enzyme activities of the Manila clam, R uditapes philippinarum, when the pH is lower than the normal value has not been studied in detail. In this study, experiments were conducted to determine how pH(7.4, 7.7, 8.0) affects the immune enzyme activities in the gill and hemocytes of the Manila clam. Membrane stability and phagocytosis increased with decrease of pH from 8.0 to 7.7 and then decreased at pH 7.4. The total protein content in the hemocytes and gills decreased with decreasing pH. Lysozyme content in the hemocytes increased with decreasing pH, and the diff erences were significant among the different pH groups(P < 0.05). Adenosine triphosphatase activity at pH 7.4 was significantly higher than in the other two groups, but no significant diff erence was observed between pH 7.7 and 8.0. Catalase activity decreased from pH 8.0 to 7.7 and then increased at pH 7.4, and the dif ferences were significant among the experimental groups( P < 0.05). These findings provide valuable information about the immune response of R. philippinarum to reduced water pH and insights for future research investigating exposure of bivalves to elevated CO_2 conditions.

Growth Performance of Larval and Juvenile Manila Clam(Ruditapes philippinarum) from Divergently Selected Individuals of a Full-Sib Family

In this study, the method of divergent selection was employed to test the larval and juvenile growth performance within a full-sib family of Manila clam Ruditapes philippinarum. The 10% largest and 10% smallest clam individuals(on the basis of shell length) of a full-sib family were selected as parents for the fast and slow growing lines, respectively. The difference in shell length was significant among the three lines(fast, control, and slow) tested. The sequence of shell length were fast line > control line > slow line. The responses to selection, realized heritability, and genetic gain were 0.06%–0.81%, 0.04%–0.47% and 0.58%–18.89% in the fast direction, respectively; and were 0.14%–1.27%, 0.08%–0.73%, and 0.31%–49.03% in the slow direction, respectively. The results suggested that there was a large portion of additive genetic variance affecting the growth in the full-sib family. Selection in the fast direction within the full-sib family would greatly improve the growth of R. philippinarum.

冲绳海槽CLAM热液区低硫逸度热液成矿

冲绳海槽是琉球俯冲系统的重要组成部分,该区热液硫化物研究对揭示非成熟弧后盆地内部热液成矿作用特征具有重要意义。CLAM热液区位于冲绳海槽中部(27°33′N、126°58′E),大量研究表明,该区成矿作用特征与海槽其他热液区存在显著差异,但其成因尚不明确。对CLAM热液区硫化物矿物组成、共生组合关系及闪锌矿微区元素组成进行了系统分析测试,在此基础上提出,该区特殊的矿物学特征及矿物化学组成可能受热液流体硫逸度控制。本文研究样品为富Fe型块状硫化物,主要由磁黄铁矿及低温闪锌矿组成,磁黄铁矿的大量结晶暗示着该区热液流体具有低硫逸度特征。热液成矿过程中,流体温度及硫逸度经历了由低到高的演化。闪锌矿中极高的Fe含量同样受控于该区流体低硫逸度条件,计算结果表明,热液流体的硫逸度值为–15,与其他受沉积物影响的热液活动区一致。流体-沉积物反应过程中,沉积物中有机质的分解可能是导致CLAM热液区热液流体硫逸度系统性降低的主要原因。

三种有机紫外吸收剂对菲律宾蛤仔(Ruditapes philippinarum)鳃组织抗氧化能力和细胞凋亡相关基因表达的影响

二苯甲酮-3(BP-3)、4-甲基苄亚基樟脑(4-MBC)和4-甲氧基肉桂酸-2-乙基己酯(EHMC)是三种常用的有机紫外吸收剂,在水环境中被频繁检出,对水生生态系统安全构成潜在威胁。为探究三种有机紫外吸收剂对菲律宾蛤仔(Ruditapes philippinarum)鳃组织抗氧化响应和相关细胞凋亡基因的影响,将蛤仔分别暴露于环境相关浓度的三种紫外吸收剂溶液中,检测鳃组织抗氧化酶活性和细胞凋亡相关基因转录水平,并通过第二代整合生物标志物响应法(IBRv2)对三种紫外吸收剂的生物毒性进行比较分析。结果显示,三种紫外吸收剂短期暴露会诱导抗氧化响应提高抗氧化能力,而长期高浓度暴露会导致抗氧化能力的降低。BP-3、4-MBC和EHMC可能通过启动线粒体途径和fas介导的死亡受体途径诱导菲律宾蛤仔鳃组织产生细胞凋亡。通过IBRv2分析发现,在环境常见浓度1μg/L的暴露水平下,短期(1 d,7 d)暴露时,BP-3对菲律宾蛤仔鳃组织表现出的综合毒性效应最强,而随着暴露时间的延长(28 d),三种紫外吸收剂表现出的综合毒性效应相近。研究结果为水环境中有机紫外吸收剂的生态风险评估提供了参考数据。