Environmental control of growth and BChl a expression in an aerobic anoxygenic phototrophic bacterium, Erythrobacter longus (DSMZ6997)

1Introduction Aerobic anoxygenic phototrophic bacteria(AAPB) are facultative heterotrophs that can utilizelight for photosynthesis. These unique-functioningbacteria are widely distributed in marine environ-ments, such as coastal waters (Shiba et al., 1991…     

用包埋脱水法冰冻保存海洋饵料金藻

用包埋脱水法冰冻保存绿色巴夫藻(Pavlova uiridis)、湛江等鞭金藻(Isochrysis zhanjiangensis)和球等鞭金藻(Isochrysis galbana 3011)等三种海洋饵料金藻，探讨了脱水速率、胶球含水量以及化冻后恢复方法对冰冻保存存活率的影响。结果表明，三种藻都在-0．9％含水量／h的平均脱水速率下获得最高存活率：各种藻在冰冻前的胶球最佳含水量不同，绿色巴夫藻为35％，湛江等鞭金藻和球等鞭金藻都为30％。化冻后，含绿色巴夫藻的胶球在培养基中22℃暗放置48h存活率最高；另两种藻在相对湿度为75％的气相中22℃暗放置12h存活率最高。在本实验条件下，绿色巴夫藻、湛江等鞭金藻和球等鞭金藻的冰冻保存的存活率可分别达到74％、15％和17％。     

山东近海牙鲆(Paralichthys olivaceus)自然和养殖群体10个微卫星基因座位的遗传多态性分析

采用微卫星遗传标记技术对山东近海牙鲆自然群体和养殖群体的遗传多样性进行了研究。实验所用牙鲆于2003年5月分别采自山东近海和青岛胶南养鱼场，各20尾，取全血或肌肉组织，以酚-仿抽提方法提取基因组DNA，利用筛选获得的10对微卫星引物进行PCR扩增，反应产物经8％非变性聚丙烯酰胺凝胶电泳分离、EB显色，用ImageMasterl D Elite(Version 3．01)软件分析电泳结果，并计算了相应的遗传学参数。结果表明，在自然和养殖群体中，10个基因座位的等位基因平均数(α)分别为6．7和6．1，每个基因座位有效等位基因数(αe)分别为1．8—6．8和2．5—6．7，群体平均杂合度(H)分别为0．8120和0．7310；两个群体间的遗传相似性系数、遗传距离和基因分化系数为0．8558、0．1557和0．0558；自然群体内每个座位上的多态信息含量(PIC)为0．59—0．84、个体识别率(DP)为0．54—0．86、非父排除率(PPE)为0．41—0．72，其累积个体识别率和非父排除率均达到0．9999，表明所选座位属中高识别力的遗传标记，可以将它们应用于今后牙鲆雌核发育群体的遗传变异分析以及进一步的遗传育种的研究中。     

A New Pursuit Mode of Nonlinear Wave Surface

The numerical mode of nonlinear wave transformation based on both the Laplace equation for water field and the Bemoulli equation for water surface is a kind of time-domain boundary problem with initial conditions. And the basis for establishing the numerical mode of nonlinear wave in time domain is to trace the position of wave free surface and to calculale the instantaneous surface height and surface potential function. This paper firstly utilizes the ‘0-1‘ combined BEM to separate the boundary by means of discretization of Green‘ s integral equation based on the Laplace equation, then separates the free surface of wave with FEM and derives the FEM equation of wave surface that satisfies the nonlinear boundary conditions. By jointly solving the above BEM and FEM equations, the wave potential and surface height could be obtained with iteration in time domain. Thus a new kind of nonlinear numerical mode is established for calculating wave transformation. The wave test in the numerical wave tank shows that the numerical simulation with this mode is of high accuracy.     

基于雷达海冰图像互相关的冰漂流场测量

我国的渤海和黄海北部在每年冬季都出现不同程度的冰情,它直接影响结冰海区的石油平台、船舶以及港口等设施的正常作业,对海冰的观测与预报随着上述海区的开发利用越发显得重要,利用航海雷达连续准确地跟踪海冰漂移运动轨迹,是当今观测、调查、研究冰漂流移动规律的有效方法之一,我国的科研人员利用雷达成像技术对渤海的冰情进行了长期的雷达海冰观测、研究,在由雷达海冰图像对海冰的物理特征的识别、分类以及冰漂流场测量方面取得了一些进展[1-4]。     

河口涨落潮槽水动力特征及河槽类型判定

在前人对河口冲刷槽研究的基础上,选择长江口南支、新桥水道、南小泓和南港主槽作为典型涨、落潮槽研究对象,以2001年洪季和2003年枯季实测资料为根据,比较分析了长江口涨落潮槽的水流、泥沙、优势流和优势沙等动力特征,结果表明用单一因子分析河槽性质不够全面.提出了一个(无量纲因子)河槽类型系数(λ)来综合表述河槽的多种水文泥沙特征,可以较全面地用多个影响因子来合理地判断河槽类型.     

Seasonal variations of alkenones and U37 in the Chesapeake Bay water column

Alkenone unsaturation indices (U^K₃₇ and U^K′₃₇) have long been used as proxies for surface water temperature in the open ocean. Recent studies have suggested that in other marine environments, variables other than temperature may affect both the production of alkenones and the values of the indices. Here, we present the results of a reconnaissance field study in which alkenones were extracted from particulate matter filtered from the water column in Chesapeake Bay during 2000 and 2001. A multivariate analysis shows a strong positive correlation between U^K₃₇ (and U^K′₃₇) values and temperature, and a significant negative correlation between U^K₃₇ (and U^K′₃₇) values and nitrate concentrations. However, temperature and nitrate concentrations also co-vary significantly. The temperature vs. U^K₃₇ relationships (U^K₃₇=0.018 (T)−0.162, R²=0.84, U^K′₃₇=0.013 (T)−0.04, R²=0.80) have lower slopes than the open-ocean equations of Prahl et al. [1988. Further evaluation of long-chain alkenones as indicators of paleoceanographic conditions. Geochimica et Cosmochimica Acta 52, 2303–2310] and Müller et al. [1998. Calibration of the alkenone paleotemperature index U^K′₃₇ based on core-tops from the eastern South Atlantic and the global ocean (60°N–60°S). Geochimica et Cosmochimica Acta 62, 1757–1772], but are similar to the relationships found in controlled studies with elevated nutrient levels and higher nitrate:phosphate (N:P) ratios. This implies that high nutrient levels in Chesapeake Bay have either lowered the U^K₃₇ vs. temperature slope, or nutrient levels are the main controller of the U^K₃₇ index. In addition, particularly high abundances (>5% of total C₃₇ alkenones) of the tetra-unsaturated ketone, C_37:4, were found when water temperatures reached 25 °C or higher, thus posing further questions about the controls on alkenone production as well as the biochemical roles of alkenones.     

Fluxes and sources of suspended organic matter in an estuarine turbidity maximum region during low discharge conditions

Water column concentrations of total suspended solids (TSS), particulate organic carbon (POC) and particulate nitrogen (PN) were measured at three different depths in four different locations bracketing the estuarine turbidity maximum (ETM) along the main channel of a temperate riverine estuary (Winyah Bay, South Carolina, USA). Measurements were carried out over full tidal cycle (over 24 h). Salinity, temperature, current magnitude and direction were also monitored at the same time throughout the water column. Tidally averaged net fluxes of salt, TSS, POC and PN were calculated by combining the current measurements with the concentration data. Under the extreme low river discharge conditions that characterized the study period, net landward fluxes of salt were measured in the lower part of the study area, suggesting that the landward transport through the main channel of the estuary was probably balanced by export out through the sides. In contrast, the net fluxes of salt in the upper reaches of the study area were near zero, indicating a closed salt balance in this part of the estuary. In contrast to salt, the net fluxes of TSS, POC and PN in the deeper parts of the water column were consistently landward at all four sites in Winyah Bay indicating the non-conservative behavior of particulate components and their active transport up the estuary in the region around the ETM.The carbon contents (%POC), carbon:nitrogen ratios (org[C:N]a) and stable carbon isotopic compositions (δ¹³C_POC) of the suspended particles varied significantly with depth, location and tidal stage. Tidally averaged compositions showed a significant increase up the estuary in the %POC and org[C:N]a values of suspended particles consistent with the preferential landward transport of carbon-rich particles with higher vascular plant debris content. The combination of tidal resuspension and flood-dominated flow appeared to be responsible for the hydrodynamic sorting of particles along the estuary that resulted in denser, organic-poor particles being transported landward less efficiently. The elemental and isotopic compositions indicated that vascular C₃ plants and estuarine algae were the major sources of the particulate organic matter of all the samples, without any significant contributions from salt marsh C₄ vegetation (Spartina alterniflora) and/or marine phytoplankton.     

Numerical Solution of Lock-Release Gravity Current with Viscous Self-Similar Regime

Lock-release gravity currents with a viscous self-similar regime are simulated by use of the renormalization group(RNG) k - ε model for Reynolds-stress closure. Besides the turbulent regime with initially a slumping phase of a conslant current front speed and later an inviseid self-similar phase of front speed decreasing as t^-1/3(where t is the time measured from release), the viseous self-similar regime is satisfactorily reproduced with front speed decreasing as t^-4/5,consistent with well known experimental observations.     

A Forced System of Two Cylinders with Various Spacings

The spectrum characteristics and wake structures for a circular cylinder oscillating in a wake are investigated by use of the currently modified virtual boundary method. A forced system of two cylinders with a small spacing ( the downstream one is made to oscillate in the transverse direction) is studied and interesting flow characteristics are observed. A vortex switch and the change of vortex modes (between 2S mode and 2P mode) are observed in the “lock-in“ region. Vortex bands are formed and lost with the increasing excitation frequency. Information concerning saddle points in the flow field is obtained for different excitation frequencies. For a forced system of two cylinders with a large spacing, the upstream cylinder sheds vortexes because there is no downstream cylinder oscillating in the wake. No distinct “lock-in“ response is found for the downstream cylinder.