双酚A暴露对不同黑色素含量长牡蛎的影响研究

长牡蛎的壳色有很多种,其中壳色较深个体(黑壳)比较浅个体(白壳)的外套膜中含有更多的黑色素。本研究采用高效液相色谱-质谱法(HPLC-MS/MS)测定天然海水中白壳与黑壳长牡蛎外套膜双酚A (BPA)含量,发现黑壳长牡蛎外套膜中的BPA含量较白壳长牡蛎低(P0.05)。由于黑色素合成过程中的关键——酶酪氨酸酶是一种酚氧化酶,可以通过对氧化酚类或芳胺类等多种底物的氧化起催化作用,推测其在BPA等酚类毒物的降解中也发挥重要作用。为了进一步研究不同黑色素含量牡蛎对BPA降解能力和对BPA损伤抵抗能力的差异,本实验进行了浓度为1 mg/L,1.5 mg/L和2 mg/L的BPA亚慢性暴露实验:通过对暴露后长牡蛎外套膜组织中BPA含量分析发现,白壳与黑壳长牡蛎外套膜中BPA含量均随着暴露浓度的升高而升高,且3种浓度BPA亚慢性暴露后,黑壳长牡蛎外套膜BPA含量均低于白壳长牡蛎,但是差异不显著(P0.05)。采用3种浓度BPA亚慢性暴露后,黑壳长牡蛎外套膜组织中活性氧(ROS)荧光值均显著低于白壳长牡蛎(P0.01)。通过对外套膜组织学观察发现,2 mg/L的高浓度BPA暴露使白壳长牡蛎外套膜组织发生了明显的病理变化,黑壳长牡蛎外套膜未发生明显的病理变化。可见,黑壳长牡蛎对BPA暴露可能具有更强的抵抗能力。     

Reconstructing pre-colonial oyster demographics in the Chesapeake Bay, USA

Recent estimates of growth and mortality rates in extant Chesapeake Bay, USA oyster (Crassostrea virginica) populations are used to quantify changes in both population abundance (dN/dT) and shell accretion (dS/dT) associated with modern population demographics. The demographics of oyster populations that would be required to maintain reef accretion rates commensurate with sea level rise over geological time frames are examined using estimates of oyster longevity in pre-colonial (pre -1600) times combined with parallel estimates of pre-disease endemic mortality. The analysis demonstrates that modern populations, with their disease related, age-truncated demographics, are generally not capable of maintaining and building biogenic reefs through accretion. Estimates of filtration rates associated with Chesapeake Bay oyster populations prior to 1600 considerably underestimate actual benthic-pelagic coupling during that period. Pristine oyster populations would have supported water column turnover rates on the order of minutes to hours. Thus, the spatial footprint of oyster reefs was limited by available productivity in the estuary. Accretion rate calculations for pristine (pre-1600) oyster reefs describe the intimate relationship between benthic-pelagic coupling and the presence or absence of oyster reefs and the associated communities.     

Modelling growth and reproduction of the Pacific oyster Crassostrea gigas: Advances in the oyster-DEB model through application to a coastal pond

A bio-energetic model, based on the DEB theory exists for the Pacific oyster Crassostrea gigas. Pouvreau et al. [Pouvreau, S., Bourles, Y., Lefebvre, S., Gangnery, A., Alunno-Bruscia, M., 2006. Application of a dynamic energy budget model to the Pacific oyster, C. gigas, reared under various environmental conditions. J. Sea Res. 56, 156–167.] successfully applied this model to oysters reared in three environments with no tide and low turbidity, using chlorophyll a concentration as food quantifier. However, the robustness of the oyster-DEB model needs to be validated in varying environments where different food quantifiers reflect the food available for oysters, as is the case in estuaries and most coastal ecosystems. We therefore tested the oyster-DEB model on C. gigas reared in an Atlantic coastal pond from January 2006 to January 2007. The model relies on two forcing variables: seawater temperature and food density monitored through various food quantifiers. Based on the high temperature range measured in this oyster pond (3–30 °C), new boundary values of the temperature tolerance range were estimated both for ingestion and respiration rates. Several food quantifiers were then tested to select the most suitable for explaining the observed growth and reproduction of C. gigas reared in an oyster pond. These were: particulate organic matter and carbon, chlorophyll a concentration and phytoplankton enumeration (expressed in cell number per litre or in cumulative cell biovolume). We conclude that when phytoplankton enumeration was used as food quantifier, the new version of oyster-DEB model presented here reproduced the growth and reproduction of C. gigas very accurately. The next step will be to validate the model under contrasting coastal environmental conditions so as to confirm the accuracy of phytoplankton enumeration as a way of representing the available food that sustains oyster growth.     

长牡蛎早期胚胎发育中脂肪酸和氨基酸组成变化的研究

采用生物化学方法研究了长牡（Crassostrea gigas）早期胚胎发育过程中脂肪酸、氨基酸组成变化情况,分别获取受精后0、6、12、24h的胚胎或幼虫进行检测和分析,结果如下：在受精卵中共检测到27种脂肪酸,豆蔻酸（14：0）、软脂酸（16：0）、硬脂酸（18：0）,EPA（20：5ω3）和DHA（22：6ω3）...     

温度和铜离子浓度对近江牡蛎超氧化物岐化酶活力的联合效应

Superoxide dismutase(SOD) is a crucial antioxidant enzyme playing the first defense line in antioxidant pathways against reactive oxygen species in various organisms including marine invertebrates. There exist mainly two specific forms, Cu/Zn-SOD(SOD1) and Mn-SOD(SOD2), in eukaryotes. SODs are known to be concurrently modulated by a variety of environmental stressors. By using central composite experimental design and response surface method, the joint effects of water temperature(18–34°C) and copper ion concentration(0.1–1.5 mg/L) on the total SOD activity in the digestive gland of Crassostrea ariakensis were studied. The results showed that the linear effect of temperature was highly significant(P0.01), the quadratic effect of temperature was significant(P0.05); the linear effect of copper ion concentration was not significant(P0.05), while the quadratic effect of copper ion concentration was highly significant(P0.01); the interactive effect of temperature and copper ion concentration was not significant(P0.05); the effect of temperature was greater than that of copper ion concentration. The model equation of digestive gland SOD enzyme activity towards the two factors of interest was established, with R2 and predictive R2 as high as 0.961 6 and 0.820 7, respectively, suggesting that the goodness-offit to experimental data be very satisfactory, and could be applied to prediction of digestive gland SOD activity in C. ariakensis under the conditions of the experiment. Our results would be conducive to addressing the health of aquatic animals and/or to detecting environmental problems by taking SOD as a potential bioindicator.     

长牡蛎(Crassostrea gigas)野生与选育群体的微卫星遗传多样性分析

为了评估长牡蛎(Crassostrea gigas) 2个壳长性状(掌心形)快速生长选育群体(LY2-K4、LY2-K7)、1个壳高性状(速生型)快速生长选育群体(LY2-K11)和6个野生群体(QHD、LS、HD、ZH、WD、KTD)的遗传多样性和遗传结构, 用21对多态性丰富的微卫星引物对9个长牡蛎群体的269个个体进行了遗传分析。结果显示: 21个微卫星位点共检测出了460个等位基因(N_a),平均等位基因数为21.905; 21个微卫星位点的多态信息含量(PIC)均大于0.5, 具有高度遗传多态性; 选育群体LY2-K11的遗传多样性最低(N_a=13, I=2.128,H_e=0.831, PIC=0.825), 野生群体KTD的遗传多样性最高(N_a=29,I=3.112, H_e=0.941, PIC=0. 938); 189个群体位点组合有66%偏离哈代-温伯格平衡, 表明这些群体存在一定程度的杂合子缺失; 9个群体间的遗传分化指数(F_st)为0.012~0.064, 处于较低的遗传分化水平; AMOVA分析显示遗传变异主要来自于个体内; PCoA分析结果与UPGMA聚类树一致, LY2-K11群体单独聚为一类, QHD和HD群体聚为一类, 其他6个群体聚为一类。综上所述, 长牡蛎3个选育群体和6个野生群体遗传多样性均较高, 遗传分化水平较低; 选育群体LY2-K11多样性略有下降, 选育过程中应保证亲本的数量及质量, 防止因近交衰退造成遗传多样性降低, 苗种抗逆性变差。该结果将为长牡蛎新品种的选育和野生种质资源的保护提供科学指导。     

Rhythmic swimming of the isopod Exosphaeroma obtusum (Dana)

The tidal swimming rhythm of the New Zealand rocky shore isopod Exosphaeroma obtusum (Dana) is described. Peak swimming was on the ebb tide about 2.5 h after high water; the peak in the dark period was 6–8 times greater in amplitude than the daytime peak. Positive thigmotaxis was shown at all other times. The rhythm period in continuous darkness (free‐running period) was greater than tidal periodicity, and there was a semi‐lunar swimming pattern with peaks at the first and third quarters of the moon. Rheotropic experiments showed that changes in water flow did not initiate the swimming rhythm. The work was compared with the infaunal species Pseudaega punctala and the northern Eurydice pulchra. It was concluded that infaunal species rely more on endogenous control of the swimming rhythm because of their isolation, when buried, from exogenous Zeitgeber.     

The potential food poisoning hazard of Vibrio parahaemolyticus in New Zealand Pacific oysters

The level of Vibrio parahaemolyticus was generally very low in Pacific oysters sampled from 4 New Zealand oyster farms between November 1982 and May 1983. Of the 149 samples collected, only one was found to contain greater than the 1000 organisms g^‐1regarded as the maximum allowable by international standards (International Commission on Microbiological Specifications for Foods 1982: Micro‐organisms in Foods, Vol. 2. Academic Press, New York). V. parahaemolyticus was detected in 57% of the oyster samples, but 95% of these contained less than 10 organisms g^‐1. Maximum levels appeared to coincide with high water temperatures at the farm sites. Chilling, freezing, and depuration reduced V. parahaemolyticus numbers in oysters after harvest. However, holding at ambient temperatures (19–25°C) resulted in up to a 35‐fold increase in organism numbers with a maximum after one day. The food poisoning hazard from V. parahaemolyticus in New Zealand‐grown Pacific oysters thus appears to be minimal. Recommendations are made to keep harvested shellfish cool and to chill them as soon as practical.     

三倍体牡蛎在繁殖季节的生长研究

研究了在繁殖季节内三倍体太平洋牡蛎的生长情况。结果表明 ,三倍体牡蛎比二倍体对照组具有明显的生长优势。在整个繁殖期间 ,三倍体的体重明显高于二倍体。三倍体的生长速度较均匀 ,而二倍体变化较大。在集中排放前体重增长较快 ,集中排放后体重增长明显减慢。三倍体的平均体重在排放前比二倍体高 17%左右 ,在排放后则高达 30 %以上。集中排放前 ,二倍体的软体重增长很快并超过了三倍体 ,其出肉率比三倍体高 2 6 .4 8%。排放后二倍体的软体重明显降低 (降低 4 8% ) ,出肉率降低 4 0 .0 % ,而三倍体变化不明显 ,出肉率仅降低 5 .79%。繁殖高峰后三倍体的软体重比二倍体高 4 1.2 2 %。三倍体牡蛎较低但稳定的出肉率表明三倍体太平洋牡蛎具有高度的不育性 ,但三倍体的不育性并不是引起三倍体生长优势的主要原因     

四倍体太平洋牡蛎(Crassostrea gigas Thunberg)自群繁殖的研究

2004年7~8月,利用诱导的1龄四倍体太平洋牡蛎做亲本,通过解剖取卵、人工受精的方法进行四倍体的自群繁殖。结果表明四倍体太平洋牡蛎自群繁殖的受精率为95.54%,孵化率为37.38%,采用同一雌体四倍体牡蛎与二倍体雄贝杂交产生的三倍体组(TD)的受精率为85.19%,孵化率为99.9%,而以二倍体做母本、四倍体做父本的杂交组(DT)的受精率为98.73%,孵化率为87.63%,二倍体对照组的受精率为96.39%,孵化率为99.9%。四倍体牡蛎经自群繁殖培育出稚贝1130粒。经流式细胞仪分析,四倍体太平洋牡蛎幼虫和稚贝的四倍体率均达到100%。幼虫培育过程中,从孵化出D-形幼虫到出现眼点,幼虫的成活率达11.86%,眼点幼虫的变态率高达16.1%。实验证明四倍体太平洋牡蛎可以进行自群繁殖,比诱导的方法简单高效。