不同发育时期海带基因工程选择标记的研究

本文以海带(Saccharina japonica)配子体、配子体克隆及幼孢子体为实验材料,研究了不同发育时期的海带对草甘膦、草丁膦、氯霉素的敏感性,经SPSS软件计算出一定时间内3种选择试剂对不同发育时期海带的半致死剂量(LD50)。结果表明:海带配子体及配子体克隆对草甘膦和草丁膦极为敏感,对氯霉素较为敏感。4d时,草甘膦和草丁膦对海带配子体的LD50分别为8.19μg/mL和19.27μg/mL,对海带配子体克隆的LD50分别为73.69μg/mL和39.08μg/mL;而氯霉素对海带配子体及配子体克隆4天的LD50则高达742.00μg/mL和701.51μg/mL。海带幼孢子体仅对草甘膦极为敏感,4d的LD50为40.93μg/mL;对草丁膦和氯霉素较为敏感,4d的LD50分别为214.51μg/mL和907.86μg/mL。该结果说明草甘膦和草丁膦适合作为以海带配子体和配子体克隆为实验材料的基因工程选择试剂,草甘膦则更适合以海带幼孢子体为实验材料的基因工程选择试剂。     

孤雌生殖海带对草丁膦的敏感性

于1999年4－7月，以孤雌生殖海带为材料，运用统计学方法研究其对草丁膦的敏感性，以期得到一定剂量和时间范围内草丁膦对不同长度孤雌生殖海带的半数致死剂量（LD50）。结果表明，孤雌海带在0．5－1．6cm长度范围内，草丁膦的半数致死剂量与海带的长度不相关，而与草丁膦的剂量和作用时间相关。孤雌生殖海带对草丁膦比对氯霉素和潮霉素更为敏感。提示，bar基因有可能成为海带基因工程更为理想的选择标记基因。     

除草剂草丁膦抗性基因bar作为三角褐指藻基因工程选择标记的研究

研究了三角褐指藻(Phaeodactylum tricornutum)对氯霉素、卡那霉素、青霉素、链霉素、潮霉素5种抗生素和一种除草剂草丁膦的敏感性,发现三角褐指藻对草丁膦非常敏感,用统计学分析法得出了其72h半致死质量浓度为22mg/L。通过基因枪法将携带草丁膦抗性基因bar的载体pSVB导入三角褐指藻细胞中,通过草丁膦筛选成功获得了抗性藻细胞,PCR检测获得阳性结果,提示草丁膦更适合用于构建安全、高效、廉价的三角褐指藻表达系统。     

亚硝基肌(NTG)对雨生红球藻的诱变效应

用浓度分别为0，0．5，1，1．5，2，2．5，3，3．5g／L的亚硝基胍(NTG)处理雨生红球藻(Haematococcus Pluvialis)，处理后的藻细胞分别置于100mL三角烧瓶培养，3d后用细胞计数测定抑制率。结果表明，NTG浓度为2．5g／L时生长K值最大，为0．389；藻液的细胞干质量最大．为0．711g／L；虾青素含量也最多，为1．86975 mg／L，之后随着浓度的增加反而下降。     

光照强度和温度对雨生红球藻生长、虾青素及内源脱落酸积累的影响

本文探讨了光照强度和温度2个生态因子对雨生红球藻(Haematococcus plivialis)生长、虾青素及内源脱落酸积累的影响。研究表明,光照强度、温度及二者交互作用对雨生红球藻的生长、虾青素及内源脱落酸的积累均有显著影响(P0.05)。温度23℃时,细胞密度随光照强度的升高呈先上升后下降趋势,在200μmol/(m~2·s)时达到最大值4.9×105个/mL。适当的高光照强度和高温均能促进雨生红球藻中虾青素和内源脱落酸的积累,过高则起抑制作用。培养期间雨生红球藻中虾青素和内源脱落酸的最大峰值分别为6.266mg/L和322.641ng/g(干重),且最大峰值均出现于27℃、200μmol/(m~2·s)处理组。脱落酸含量的最大值出现在虾青素快速积累前,且在雨生红球藻的生活周期中,孢囊形成期的内源脱落酸含量最高。本研究所得到的规律对规模化培养雨生红球藻具有一定的指导意义。     

雨生红球藻光合和呼吸速率研究

于１９９４年在青岛以单细胞雨生红球藻为实验材料,利用ＭＣＭ改良配方制作培养洲,采用测溶解氧的方法,进行了光合和呼吸速率测定。结果表明,雨生红球藻光合速率、呼吸速率不仅与温度、光照强度有密切关系,同时还与其生活史中不同发育阶段有关。１７℃、２５℃、３３℃时,雨生红球藻游动细胞光饱和点光强度分别为２６０μＥ／（ｍ＾２．ｓ）、３２０μＥ／（ｍ＾２．ｓ）、３２０μＥ／（ｍ＾２．ｓ）左右,光补偿点光强分别为     

裙带菜配子体基因工程选择标记的研究

研究了裙带菜(Undaria pinnatifida)配子体对除草剂草丁膦的敏感性以及温度对草丁膦处理效果的影响。结果表明,裙带菜配子体对草丁膦敏感;统计学分析得出了草丁膦在不同温度条件下处理裙带菜配子体的半致死浓度(LD50)及95%可信限;温差达到10℃时,相同处理时间各组内不同处理温度样品的LD50之间呈现显著差异,第6天的LD50由10℃组的15.78 mg/L降为20℃组的11.56 mg/L和25℃组的10.33 mg/L。研究发现可以尝试采用草丁膦作为裙带菜配子体遗传转化的选择试剂。     

8种抗生素对塔玛亚历山大藻生长的影响

对一株有毒的塔玛亚历山大藻(Alexandrium tamarense(Lebour) Balech)进行了8种抗生素-氯霉素、红霉素、林可霉素、庆大霉素、金霉素、氨苄青霉素、新霉素和链霉素的敏感性实验.结果表明,该藻对抗生素较为敏感.其中的5种:氯霉素、红霉素、林可霉素、庆大霉素和金霉素,对藻8d比生长速率的EC₅₀分别为2.45μg/cm3,25.2μg/cm3,7.95μg/cm3,285u/cm3,58.7μg/cm3,可用作该藻基因工程的选择压力,其对应的抗性基因可以作为基因工程阳性选择标记基因,应用于塔玛亚历山大藻的遗传操作研究.新霉素和链霉素对A.tamarense的生长无明显抑制作用,可以用于藻株无菌化培养而应用于甲藻产毒机制和赤潮爆发机理的研究,还应用筛选出的抗生素对藻培养物进行了除菌实验.     

褪黑素对雨生红球藻(Haematococcus pluvialis)生理和虾青素积累的影响

本实验初步研究了不同浓度褪黑素(melatonin,MLT)对胁迫条件下雨生红球藻Haematococcus pluvialis LUGU生长、虾青素、相关生理指标及基因表达的影响。结果表明,10μmol/LMLT可显著提高藻细胞中虾青素产量(31.32mg/g),是对照组(13.27mg/g)的2.36倍;碳水化合物和蛋白含量同比提高了1.36、1.37倍。此外,虾青素合成相关基因pds和bkt的表达水平分别提高了5.79和12.16倍。研究表明,MLT可显著促进雨生红球藻中虾青素的积累,为利用微藻生产虾青素提供了一种有效的策略。     

雨生红球藻诱变及筛选方法的研究

为获得性状优良的雨生红球藻藻株,满足雨生红球藻商业化生产的需求。本文探索了不同诱变方式以及不同筛选条件对雨生红球藻的影响,得到了γCo~(60)辐射和离子束诱变处理以及将喹禾灵和达草灭作为筛选压对雨生红球藻的致死率曲线。确定离子束照射时间75s和γCo~(60)辐射300Gy为雨生红球藻的适宜诱变条件。喹禾灵30.0μmol/L以及达草灭0.09mmol/L为雨生红球藻的适宜筛选压浓度。对诱变后藻株与对照藻株进行了生物量、干重以及虾青素含量的比较,最终筛选得到三株性状优良的突变株,生物量较未诱变藻株分别提升了16.2%、13.8%和20.4%,虾青素含量与未诱变藻株相比提升了20.7%、15.5%和6.7%。     

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.     

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.     

A Review of Some Environmental Issues Affecting Marine Mining

This article reviews information recently available from existing marine and coastal mining for responses to environmental issues affecting marine mining at different depths. It is particularly but not exclusively concerned with those issues affecting seabed biodiversity impact and recovery. Much information has been gathered in the past 10 years from shallow mining operations for construction aggregate, diamonds, and gold, from coastal mines discharging tailings to shallow and deep water, and from experimental deep mining tests. The responses to issues identified are summarized in a series of eight tables intended to facilitate site-specific consideration. Since impacts can spread widely in the surface mixing layer SML, and can affect the biologically productive euphotic zone, the main issues considered arise from the depth of mining relative to the SML of the sea. Where mining is below the SML, the issue is whether it is environmentally better to bring the extraction products to the surface vessel for processing (and waste discharge), or to process the extraction products as much as possible on the seabed. Responses to the issues need to be sitespecific, and dependent on adequate preoperational environmental impact and recovery prediction. For deep tailings disposal from a surface vessel, there are four important environmental unknowns: (1) the possible growth of "marine snow" (bacterial flocs) utilizing the enormous quantities of fine tailings particles (hundreds or thousands of metric tons per day) as nuclei for growth, (2) the possibility that local keystone plankton and nekton species may migrate diurnally down to and beyond the depth of deep discharge and hence be subjected to tailings impact at depth, (3) the burrow-up capability of deep benthos and their ability to survive high rates of tailings deposition, and (4) the pattern and rate of dispersion of a tailings density current through the deep water column from discharge point to seabed. Actions to obtain relevant information in general and site-specifically are suggested.     

Increased Particle Fluxes at the INDEX Site Attributable to Simulated Benthic Disturbance

Particle fluxes were measured 7 m above the sea bottom during the predisturbance, disturbance, and postdisturbance periods by using time series sediment traps attached to seven deep-sea moorings deployed in the INDEX experiment site in the Central Indian Basin. The predisturbance particle fluxes varied between 22.3 to 55.1 mg m -2 day -1 . Increased and variable particle fluxes were recorded by the sediment traps during the disturbance period. The increase observed was 0.5 to 4 times more than the background predisturbance fluxes. The increases in particle fluxes (~4 times) recorded by the sediment trap located in the southwestern direction (DMS-1) were the greatest, which could be the result of preferential movement of resuspended particles generated during the deep-sea benthic disturbance along the general current direction prevailing in this area during the experimental period. Also, the traps located closer to the disturbance area recorded greater fluxes than did the traps far away, across the Deep Sea Sediment Resuspension System path. This variability in recorded particle fluxes by the traps around the disturbance area clearly indicates that physical characteristics such as grain size and density of the resuspended particles produced during the disturbance had an important effect on particle movement. The postdisturbance measurements during ~5 days showed a reduction in particle fluxes of ~50%, indicating rapid particle settlement.     

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.     

Determination of In Situ Sediment Shear Strength from Advanced Piston Corer Pullout Forces

The advanced piston corer (APC) has been used by the Ocean Drilling Program since 1985 for recovering soft sediments from the ocean floor. The pullout force measured on extracting the core barrel from the sediment is shown to correlate with the average shear strength of the sediment core measured in the ship's laboratory. A simple rule of thumb is derived relating the shear strength of the sediment to the pullout force. Multiple APC holes at individual sites allow the consistency of the pullout measurements to be assessed. The effects of different operational procedures during APC coring are also explored. Although generally applicable, the correlation between pullout force and laboratory measurements of shear strength breaks down for some APC holes, possibly because of the disturbance of some sediment types during the APC coring process. A better understanding of the physical process of APC coring, and its effect on the properties of the sediment both inside and immediately outside the core barrel, would indicate what confidence can be put on the measurement of pullout force as a way of evaluating the in situ shear strength of deep sea sediments.     

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.