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1.
采用紫外线照射的方式使精子遗传物质失活,通过细胞松弛素B(CB)的处理来抑制受精卵第二极体的释放,人工诱导紫贻贝(Mytilus gallopovincialis)雌核发育二倍体。将精子在强度为2561μW/(cm~2·s)的紫外线(254 nm)下进行时间梯度的照射,之后与正常的卵子受精,实验发现随照射时间的增加,卵裂率、早期胚胎存活率和D形幼虫发生率总体呈下降趋势,在照射55 s时D形幼虫发生率降为0。受精后25 min,用浓度0.5μg/mL的细胞松弛素B(CB)持续处理受精卵20 min,诱导出紫贻贝第二极体抑制型雌核发育二倍体。通过微卫星分析鉴定所得的子代个体均为雌核发育二倍体。 相似文献
2.
大黄鱼雌核发育二倍体的人工诱导 总被引：2，自引：0，他引：2
采用紫外线照射对大黄鱼(Pseudosciaena crocea Richardson)精子遗传物质进行完全灭活,灭活后精子与卵子受精获得雌核发育单倍体受精卵,再通过冷休克对单倍体受精卵进行倍性恢复,成功诱导出大黄鱼雌核发育二倍体。实验结果表明:(1)在紫外照射过程中照射剂量与大黄鱼精子和卵子受精后其成活率和孵化率呈现出明显的Hertwig效应,紫外照射时间超过2 min(剂量>2 400 ergs/mm2),可使大黄鱼精子遗传物质完全灭活。大黄鱼雌核发育诱导中精子遗传灭活的最适紫外照射时间为2.5 min(剂量为3 000 ergs/mm2);(2)冷休克法可成功抑制大黄鱼受精卵第二极体排放,诱导效果受处理时刻、处理时间和处理温度三因素的影响。综合雌核发育二倍体的诱导率、处理后受精卵早期胚胎存活率和仔鱼孵化率等因素,较适合的染色体加倍条件为23℃培育水温下授精后2 min,在3-4℃海水中处理10 min。 相似文献
3.
栉孔扇贝第1卵裂抑制型雌核发育二倍体的研究 总被引：5，自引：0，他引：5
利用6-二甲基氨基嘌呤(60μg/cm3;6-DMAP)和细胞松弛素B(0.5μg/cm3;CB)抑制受精卵的第1次卵裂,授精后60和65 min分别用CB和6-DMAP持续处理20和15 min,可诱导出12.5%和27.5%的第1卵裂抑制型雌核发育二倍体.细胞学观察显示,6-DMAP抑制第1次卵裂产生的雌核发育二倍体主要在第1次有丝分裂后期的受精卵,由于破坏了纺锤体和阻止了染色体分离,导致一个二倍性雌核的形成,而CB有效地阻止了第1次卵裂的胞质分裂.尽管倍化率和D型幼虫发生率较低,但该研究首次报道了栉孔扇贝第1卵裂抑制型雌核发育二倍体诱导的可行性. 相似文献
4.
人工诱导香港巨牡蛎雌核发育单倍体的研究 总被引：3，自引：0，他引：3
研究利用紫外线诱导香港巨牡蛎Crassostrea hongkongensis雌核发育的条件.结果表明,在强度为1820μW · (cm2·s)-1的紫外线(254nm)下分别照射精子0,5,10,15,20,25,30,35,40,45,50,55,60,70,80和90s后,照射30s的实验组能够保持较高的受精率(61.6%),该组的D形幼虫发生率为0,出现"Hertwig效应".研究表明,在强度为1 820 μW·(cm2·s)-1的紫外线下照射精子30s是获得香港巨牡蛎雌核发育单倍体的适宜条件.研究还表明受精率和D形幼虫发生率随照射时间的增加而下降,遗传失活的精子与正常卵子受精后其胚胎发育至D形幼虫前期停止.经紫外线照射的精子授精后所产生的单倍体胚胎发育速度慢于正常受精所产生的二倍体胚胎,各照射组均出现非整倍体. 相似文献
5.
异源精子诱导牙鲆雌核发育二倍体 总被引：13，自引：0，他引：13
采用紫外线照射处理的石鲽精子和受精后冷休克的方法诱导了牙鲆雌核发育。结果表明:用2只平行的相距15cm的20W紫外灯管,照射距离为10cm,在5~100s时间范围内照射石鲽精子时,受精卵的发育表现了典型的哈特维希效应,照射40s的精子所得胚胎的孵化率达到最高峰(41%),染色体观察结果显示,此照射剂量组的所有胚胎均为单倍体(n=24),表明照射精子遗传失活的有效性和可靠性。如果冷休克处理前受精卵保持在(15.5±0.5)℃,受精卵在一定的休克温度(0~10℃)条件下,用不同休克起始时间(受精后1~10min)及冷休克处理持续时间(15~90min)均能诱导染色体加倍。对冷休克处理条件的优化结果表明,在2~4℃条件下,受精后3min开始、冷休克处理45min时,二倍体诱导率最高,达79.7%。染色体鉴定显示,处理组的正常胚胎均为二倍体(2n=48),未发现单倍体和非整倍体。 相似文献
6.
利用6-二甲基氨基嘌呤(60 mg/L;6-DMAP)抑制第一卵裂,成功诱导出栉江珧(Atrina pectinata)雌核发育二倍体.研究结果表明在培养温度为24℃的条件下,受精后60 min用质量浓度为60 mg/L的6-DMAP处理栉江珧受精卵15 min进行雌核发育二倍体的诱导效果理想,D形幼虫发生率和诱导率分别为14.7%和22.7%.细胞学观察显示,6-DMAP阻止了纺锤体的形成和染色体的移动,导致一个融合的二倍性雌性原核的形成.本研究结果首次提供了栉江珧雌核发育二倍体的细胞学证据. 相似文献
7.
采用紫外线(UV)灭活的同源精子通过冷休克抑制第二极体排放诱导黄姑鱼(Nibea albiflora)的雌核发育。结果表明,黄姑鱼精子最适的灭活剂量为420mJ/cm2,紫外照射剂量与黄姑鱼精子和卵子授精后的受精率及孵化率之间表现出明显的Hertwig效应。多次试验筛选的黄姑鱼雌核发育的最适条件为授精后2min于3℃处理8min。雌核发育仔鱼经形态学和流式细胞仪鉴定为二倍体。进一步利用10对微卫星分析了遗传物质在亲本和子代中的传递情况,结果表明雌核发育后代的等位基因完全来自于母本,没有父本基因参与;雌核发育后代在5个微卫星位点具有较高的重组率,使其与母本保持了高度同质性。 相似文献
8.
9.
人工诱发合浦珠母贝雌核二倍体发生及“Hertwig效应”的初步研究 总被引：2，自引：0，他引：2
用中心波长为254nm、光照强度为4μW/cm~2的紫外线,照射合浦珠母贝[Pinctada ma-tensil(D_o)]和长耳珠母贝[Pinctada chemnitzi(P_o)]的精子,然后与合浦珠母贝的正常卵授精,在0-150s的照射范围内,从早期胚胎存活率上可以观察到“Hertwig效应”的存在,由此得到的单倍体和非整倍体胚胎在孵化前死亡。精子经120s紫外线照射后,染色体完全失活,但受精作用仍能正常发生。长耳珠母贝精子经 120s照射,异种授精(♀合×♂长)后21min,用浓度为0.4mg/l的细胞松弛素B处理15min,抑制受精卵的第二极体排放,可以诱发合浦珠母贝产生74.0％雌核二倍体胚胎,其孵化率为2.1％。 相似文献
10.
一种新方法——低渗诱导虾夷扇贝三倍体的研究 总被引：2，自引：0，他引：2
研究开发了1种多倍体诱导的新方法,采用低渗抑制受精卵第2极体(PB2)的释放诱导虾夷扇贝(Patinopecten yessoensis)三倍体.结果表明:以低渗盐度S=12,在第一个PB2出现时开始处理,持续处理20 min,诱导率可高达(84.74±3.82)%;三倍体处理组的幼虫比对照组具有明显的生长优势,但是幼虫存活率低于二倍体对照组. 相似文献
11.
Chandralata Raghukumar G. Sheelu P. A. Loka Bharathi Shanta Nair C. Mohandass 《Marine Georesources & Geotechnology》2001,19(1):1-16
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. 相似文献
12.
Arne Schnack-Friedrichsen Angela M. Davis Jim D. Bennell Dei G. Huws 《Marine Georesources & Geotechnology》2001,19(4):221-243
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. 相似文献
13.
Derek V. Ellis 《Marine Georesources & Geotechnology》2001,19(1):51-63
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. 相似文献
14.
G. Parthiban 《Marine Georesources & Geotechnology》2000,18(3):223-235
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. 相似文献
15.
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. 相似文献
16.
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。 相似文献
17.
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. 相似文献
18.
Shigehisa Nakamura 《Marine Geodesy》2000,23(1):55-61
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. 相似文献
19.
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. 相似文献
20.