利用不同盐度诱导长牡蛎三倍体的研究

采用低盐度(4、6、8、10、12、14、16)和高盐度(40、45、50、55、60、65、70)在40%~50%受精卵出现第一极体时处理10和15min,进行长牡蛎三倍体的诱导。在低盐度诱导三倍体实验中,随着盐度降低,D型幼虫孵化率逐渐降低,处理10和15min的卵裂率差异显著(P0.05),孵化率差异不显著(P0.05)。当盐度为8时,处理受精卵10与15min,三倍体诱导率最高分别可达84.4%和91.0%,两处理组三倍体诱导率差异显著(P0.05)。在高盐度诱导三倍体实验中,随着盐度升高,D型幼虫孵化率逐渐降低,处理10和15min的卵裂率和孵化率均差异显著(P0.05)。当盐度为55时,处理受精卵10min,三倍体诱导率最高为80.3%;当盐度为60时,处理受精卵15min,三倍体诱导率最高为97.1%,两处理组三倍体诱导率差异显著(P0.05)。研究发现,在盐度为8和60条件下,40%~50%的受精卵出现第一极体时,处理15min,长牡蛎三倍体诱导率最高。     

华贵栉孔扇贝三倍体的研究

本文报道了用细胞松驰素B、高温和低温休克等方法诱导华贵栉孔扇贝（Chlamys nobilis）三倍体的实验结果。在26.0～28.0℃条件下，选用不同浓度的细胞松驰素B0.1、0.3、0.5、0.7和1.0mg/dm^3，在受精后15min，处理受精卵15min，三倍体诱导率分别为12.5%、37.5%、68.0%、66.6%和81.0%，其中0.5～1.0mg/dm^3浓度的细胞松驰素B对改变倍性最有效。高温休克选用31.0、33.0、35.0和37.0℃处理受精卵，最高三倍体诱导率达46.7%（33.0℃,处理15min）。低温休克选用6.0、8.0、10.0和12.0℃处理受精卵，最高三倍体诱导率为40.7%（10.0℃，处理20min）。实验结果表明，随着处理强度的增大和处理时间的延长，三倍体诱导率增高、但孵化率下降，畸型率上升。用高温休克处理的实验组幼虫生长速度较对照组快。作者认为，在商业性生产中，温度休克是诱导扇贝三倍体的一种简便、有效的方法。文中还就细胞松驰素B与温度休克诱导三倍体的机制进行了讨论。     

三种化学诱导剂诱导太平洋牡蛎三倍体的比较研究

从三倍体率、D幼孵化率、幼虫生长速度、生产成本等方面比较了细胞松驰素 B、二甲基氨基嘌呤、咖啡因三种化学诱导剂诱导太平洋牡蛎产生三倍体的效果。 CB的三倍诱导率最高 ,为91.5% ,但 D幼孵化率最低 ,仅为 5.8% ,且成本最高 ,为 6 - DMAP和咖啡因的 4倍和 50倍。 6 -DMAP的三倍体诱导率略低于 CB,为 88.0 % ,但 D幼孵化率最高 ,为 6 0 .5% ,其成本仅为 CB的1/ 4。咖啡因的三倍体诱导率最低 ,为 82 .4 % ,幼虫孵化率为 30 .2 % ,但其成本最低 ,仅为 CB的 2 %和 6 - DMAP的 8%。三种诱导剂诱导的三倍体群幼虫在生长速度及成活率方面无显著差别。     

6-DMAP诱导黄河口近江牡蛎(Crassostrea ariakensis)三倍体的研究

用6-二甲基氨基嘌呤(6-DMAP)进行了黄河口近江牡蛎(Crassostreaariakensis)的三倍体诱导,以卵裂率、孵化率、诱导三倍体率和三倍体诱导组幼虫的生长率、存活率、三倍体率为指标,研究了诱导浓度、起始诱导时间、诱导持续时间三个因素对黄河口近江牡蛎三倍体的诱导效果。结果表明,三因素对近江牡蛎三倍体诱导效果的影响程度为起始诱导时间诱导持续时间诱导浓度。温度25℃,诱导浓度为300—450μmol/L,起始诱导时间为受精后14min,诱导持续时间为15min时,诱导三倍体率可达51.39%—71.67%,卵裂率、孵化率、幼虫壳高日平均生长率和幼虫平均存活率分别能达到65.16%—81.57%、61.25%—86.78%、8.76—9.88μm/d、69.16%—73.29%,眼点幼虫时期三倍体率达53.33%—62.16%。本研究为黄河口近江牡蛎的三倍体诱导提供了理论依据。     

高盐诱导太平洋牡蛎(Crassostrea gigas)三倍体的初步研究

初步探讨了利用高盐抑制受精卵第2极体(PB2)的释放的方法诱导太平洋牡蛎(Crassostrea gigas)三倍体。水温25℃条件下,分别进行不同高盐处理(盐度梯度为40、45、50、55、60、65、70、75、80)、不同处理时机(受精卵出现第一个PB1,30%和50%PB1,出现第一个PB2,50%PB2)和不同持续处理时间(10~25min)的实验,通过胚胎孵化率、三倍体诱导率及综合评价指数的分析表明,高盐诱导太平洋牡蛎三倍体的最适方案为:当50%受精卵出第一极体时,以盐度为65的高盐海水处理受精卵20min,三倍体诱导率最高达65.53%。     

6-DMAP诱导缢蛏三倍体的研究

用6-DMAP抑制受精卵第二极体排放的方法诱导缢蛏三倍体的试验．结果表明：6-DMAP在100～500μmol／dm^3处理浓度范围内均可以诱导出三倍体，随着药物处理浓度和处理时间的提高，三倍体倍化率和D形幼虫畸形率有不同程度的提高，而D形幼虫孵化率会随之下降．综合来看，在30％卵子受精并出现第一极体，6-DMAP浓度为300μmol／dm^3和处理持续时间为20min时的处理组的处理效果优于其他处理组组合．     

长牡蛎三倍体的诱导和培育

本文报道了采用高温结合咖啡因、CB、6 DMAP等方法诱导长牡蛎三倍体的研究结果。结果表明 :CB、6 DMAP的三倍体诱导率高 ,分别达 85 .39%和81 .2 6 % ,适用于大规模生产。高温结合咖啡因处理三倍体诱导率低 ,且存活率也很低。采用CB抑制受精卵第二极体排放诱导培育出三倍体种苗 7.2× 1 0 7粒。     

利用细胞松弛素B抑制第一极体排放诱导近江牡蛎(Crassostrea rivularis)四倍体

采用细胞松弛素B（CB）处理受精卵,抑制第一极体的排放,对近江牡蛎四倍体的诱导和培育进行了研究.结果表明,近江牡蛎在25-28℃时受精卵发育同步性较高.在28℃条件下,CB适宜处理剂量为0.6mg/L.在个别受精卵出现第一极体时实施处理,至对照组的第一极体出现率达到50%终止处理,四倍体的诱导效果较好.5个处理组D形幼虫的平均孵化率为11.0%,显著低于对照组72.4%的平均孵化率.在受精后4-12d期间处理组幼虫的存活率显著低于对照组.处理组胚胎和D形幼虫阶段四倍体的平均比例分别为41.8%和37.9%.四倍体的比例随着幼虫的生长发育呈下降趋势,至受精后12d在各处理组已检测不到四倍体.2组幼虫完成附着变态,从受精卵至稚贝的累计存活率平均为0.3%.本研究结果表明,使用CB处理抑制受精卵第一极体的释放可以有效诱导近江牡蛎四倍体,但所获得的四倍体幼虫存活力差,需要在未来的研究中解决.     

低渗诱导栉孔扇贝三倍体及与其它方法的比较

采用低渗抑制受精卵第2极体(PB2)的释放诱导栉孔扇贝(Chlamys farreri)三倍体。水温20℃时,分别进行不同盐度处理(8~20)、不同起始处理时间(受精后15~40 min)和不同持续处理时间(10~25 min)的实验,对三倍体处理组和对照组幼虫的生长进行观察,同时将低渗、6-DMAP、热休克、冷休克4种诱导方法进行对比。结果表明:受精后30 min开始处理20 min,诱导率最高,可达(92.36±2.41)%,卵裂率为(49.78±6.51)%,孵化率为(61.82±1.63)%;D形幼虫期,处理组幼虫表现出明显的生长优势(P0.01),不仅生长速度快,而且发育到变态时个体比二倍体大;低渗诱导的三倍体率与6-DMAP相比无显著差异(P0.05);与热休克和冷休克相比差异显著(P0.01)。     

细胞松弛素B诱导盘鲍三倍体的研究

每次在盘鲍三倍体诱导试验之前,都进行预试验,观察和了解在该温度下受精卵第一极体和第二极体出现的时间.当40%～50%的盘鲍受精卵出现第一极体时,采用以不同浓度的细胞松弛素B进行不同持续时间的处理抑制受精卵第二极体出现的方法诱导其三倍体.试验结果表明,在水温24.5℃下,诱导的起始时间为27min,诱导的浓度为0.70mg/dm^3,诱导的持续时间为10min,是三个诱导参数的较佳组合,其三倍体率达75%以上,并且胚胎的孵化率达75%,幼体的畸形率较低,为50%.本文还就诱导三倍体的一些问题进行了讨论.     

Microbial Biomass and Organic Nutrients in the Deep-Sea Sediments of the Central Indian Ocean Basin

In order to assess the impact of deep-sea mining on the in situ benthic life, we measured the microbial standing stock and concentration of organic nutrients in the deep-sea sediments of the Central Indian Ocean Basin in the Indian pioneer area. Sediments were collected using box core and grab samples during September 1996. The total bacterial numbers ranged from 10 10 -10 11 cells per g -1 dry weight sediment. There was a marginal decrease in the number of bacteria from surface to 30 cm depth, though the subsurface section registered a higher number than did the surface. The highest numbers were encountered at depths of 4-8 cm. The retrievable number of bacteria were two orders less in comparison with the direct total counts of bacteria. An almost homogeneous distribution of bacteria, total organic carbon, living biomass, and lipids throughout the depth of cores indicates active microbial and benthic processes in the deep sea sediments. On the other hand, a uniform distribution of total counts of bacteria, carbohydrates, and total organic carbon in all the cores indicates their stable nature and suggests that they can serve as useful parameters for long-term monitoring of the area after the benthic disturbance. Further studies on temporal variability in this region would not only verify the observed norms of distribution of these variables but would also help to understand restabilization processes after the simulated benthic disturbance.     

Assessing the Validity of Seismo-Acoustic Predictor Equations for Obtaining Seabed and Sub-Surface Sediment Physical Properties

The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths.     

海上大直径钢管桩打桩过程中桩周土强度弱化研究

海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。     

Geoacoustic Inversion via Genetic Algorithm and Its Application to Manganese Sediment Identification

An acoustic inversion method using a wide-band signal and two near field receivers is proposed and applied to multiple layered seabed models including a manganese sediment. The inversion problem can be formulated into a probabilistic model comprised of signals, a forward model, and additive noise. The forward model simulates wide-band signals, such as chirp signals, and is chosen to be the source-waveletconvolution plane wave modeling method. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the possible numerical ranges for a priori uniform distribution is based. The genetic algorithm is applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L 2 norm of the difference between measured and modeled signals. Not only the marginal pdf but also its statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm.     

Interannual Sea Level Variations and Annual Tides in the Northwestern Pacific

Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone.     

Deep-Sea Sediment Compression Curves: Some Controlling Factors, Spurious Overconsolidation, Predictions, and Geophysical Reproduction

Oedometer tests have been carried out on 70 undisturbed surficial clays (at approximately 250 mm below the mudline), mostly collected by free-fall corers from sites widely scattered throughout the deep-sea North Atlantic. Acoustic measurements were also made, initially on contiguous samples and ultimately on the same sample using a geophysically instrumented oedometer which also collected electrical resistivity data. Apart from those quiescent areas below the carbonate compensation depth, such as north of the West Indies where very fine clays exist, most of the samples are silty clays whose geotechnical-geophysical properties are dependent on the type of clay minerals present (and their ability to take in moisture), the sand-size fraction, and the quantity of carbonate present. Thus the pure clays have high compressibilities which decrease on the addition of coarse particles, while the converse is true for the acoustic parameters, these increasing with the sand fraction. Using the notion of the intrinsic compression line for all samples, and comparison to it of the measured compression curves, it is clear that, contrary to some previously held ideas, most deep-sea clays are normally consolidated; the addition of carbonate has the effect of creating an open, stronger sediment skeleton. Interestingly, where information is available, the variation with depth of a sample's acoustic velocity follows the void ratio pressure relationship of the compression curve. This allows the construction of an in-situ sediment compression curve using the in-situ geophysical observations.     

Flow Cytometric Analysis of Coastal Lagoon Bacterioplankton and Picophytoplankton: Fixation and Storage Effects

The effect of different fixation and storage protocols on the flow cytometric (FCM) simultaneous analysis of bacterioplankton and phytoplankton in coastal seawater samples (Mediterranean coastal lagoons) was investigated. FCM measurements (cell number, fluorescence and scatter characteristics) were obtained through DAPI staining. Three fixatives [glutaraldehyde (GA), formaldehyde (FA) and paraformaldehyde (PFA)] and two storage (3 months duration) methods (5 °C and −196 °C) were tested. Two dominant populations were detected in studied samples: bacteria and eukaryotic picophytoplankton. Adding fixatives (2% final concentration) appears necessary to obtain FCM exhaustive counts of all the bacteria and phytoplanktonic cells. This was related to the permeation effect of fixatives which allowed a better DAPI staining of the cells. Maximum fluorescence, i.e. optimal staining of the cells was obtained with FA or PFA, and significant lower fluorescences with GA. Fixed samples stored at 5 °C induced rapid cell loss. Only storage in liquid nitrogen of samples fixed with FA or PFA, allows mid-term (≥4 months) preservation of bacteria or picophytoplankton cell numbers, and limited evolution of DAPI-induced fluorescence and scatter characteristics.     

Phylogenetic diversity and phenotypic characterization of cultivable bacterioplankton isolated from polar oceans

A set of 27 marine planktonic bacteria isolated from the polar regions was characterized by 16S rDNA sequencing and physiological and biochemical testing. More than half of these bacteria were positive for caseinase, gelatinase and 13-glucosidase, and could utilize glucose, maltose or malic acid as carbon source for cell growth. Twelve isolates expressed nitrate reduction activities. Except for one antarctic isolate BSwlO175 belonging to Actinobacteria phylum, these isolates were classified as γ-Proteobacteria, suggesting that γ-Proteobacteria dominated in cultivable marine bacterioplankton at both poles. Genus Pseudoalteromonas was the predominant group in the Chukchi Sea and the Bering Sea, and genus ShewaneUa dominated in cultivable bacterioplankton in the Prydz Bay. With sequence similarities above 97%, genus Psychrobacter was found at both poles. These 27 isolates were psychrotolerant, and significant 16S rDNA sequence similarities were found not only between arctic and antarctic marine bacteria （ 〉 99% ）, but also between polar marine bacteria and bacteria from other aquatic environments （ ≥ 98.8% ）, including temperate ocean, deep sea, pond and lake, suggesting that in the polar oceans less temperature-sensitive bacteria may be cosmopolitan and have a bipolar, even global, distribution at the species level.