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多倍体贝类的繁殖生物学研究进展 总被引：2，自引：0，他引：2
本文综述了国内外多倍体贝类繁殖生物学的研究现状。主要是从多倍体贝类的性腺发育、生殖细胞、减数分裂、繁殖力以及其性成熟年龄和性比等方面进行了论述。三倍体贝类的性腺虽然有一定程度的发育，但总体表现出高度的不育，而四倍体贝类的性腺发育正常；三倍体、四倍体贝类的生殖细胞明显大于同龄的二倍体的生殖细胞；多出的几套染色体使多倍体贝类减数分裂时染色体的分离形式复杂化；多倍体贝类的性成熟年龄与二倍体基本一致，三倍体贝类雌雄比例与二倍体有所不同，雌雄同体的比例增大。 相似文献
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将中华绒螯蟹三倍体大眼幼体群体 (三倍体率 64.38% )在池塘中养殖 ,对其早期生长及营养进行测定。结果表明 ,从三倍体群体自身的生长状况看 ,放养后 68— 78天是整个测量期间三倍体群体生长最快的阶段 ,其中壳长增长显著 (P <0 .0 5 ) ,壳宽和体重的增加极显著 (P <0 .0 1 )。与二倍体群体相比 ,放养后 68— 1 0 6天 ,三倍体群体在壳长、壳宽、体重上都表现出明显的生长优势 (P <0 .0 1 )。三倍体幼蟹蟹体氨基酸总量高于正常二倍体幼蟹 ,必需氨基酸中苏氨酸、苯丙氨酸、缬氨酸、亮氨酸、精氨酸、异亮氨酸、组氨酸和赖氨酸的含量高于二倍体 ,而蛋氨酸的含量则低于二倍体幼蟹。蟹体中不饱和脂肪酸所占比例三倍体幼蟹低于正常二倍体 ,EPA、DHA及多不饱和脂肪酸所占的比例也低于二倍体。结果表明 ,三倍体幼蟹的生长比正常二倍体具有优势 ,并且在营养组成上也和二倍体有所差异。 相似文献
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三倍体牡蛎在繁殖季节的生长研究 总被引：2，自引：0，他引：2
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 相似文献
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合浦珠母贝二倍体、三倍体和非整倍体群体的基因杂合度与生长比较 总被引：6，自引：0，他引：6
采用淀粉凝胶电泳方法对合浦珠母贝Pinctadamartensi(D.)雌性三倍体与雄性二倍体交配,细胞松弛素B抑制其受精卵第一极体释放产生的二倍体、三倍体及非整倍体3个群体进行了同工酶研究。二倍体、三倍体及非整倍体群体在6个多态位点的平均基因杂合度分别为0.255±0.087,0.286±0.097,0.275±0.089,三倍体的杂合度高出二倍体约12%,表明多倍体诱导能增加诱导群体的杂合度。但在单个位点上,三倍体的杂合度不一定高于二倍体;在各自群体内,平均杂合位点数与生长间无明显的相关性,单个位点上的杂合子也未完全表现出其生长大于纯合子,且差异不明显(p>0.05)。因此,合浦珠母贝三倍体的快速生长难以完全用杂合度增高假说解释,只能说明诱导处理能使三倍体的杂合度增高,而能量再分配和"巨型性"可能对其快速生长起着不可忽视的作用。非整倍体群体的杂合度高于二倍体群体,但其生长却小于二倍体,其原因可能是染色体的增减对机体的生长有一定的影响。 相似文献
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为了评估香港牡蛎二倍体及三倍体幼虫生物学特征,于2013~2015年,在湛江和北海两地比较了二倍体及三倍体幼虫生长、存活及变态差异,计算了三倍体优势率,评估了倍性与环境效应互作对其表型性状的影响。结果表明:三倍体D形幼虫显著大于二倍体幼虫,之后,伴随着个体增长,生长优势逐渐增大,15日龄时的三倍体优势率为8.9%~9.1%。三倍体幼虫存活力与二倍体相当,未出现大量致死现象。三倍体变态规格显著大于二倍体,其优势率为5.1%~5.3%;三倍体变态时间显著低于二倍体,但其变态率与二倍体相当,不存在显著差异(p>0.05)。经过双因子分析模型的方差分析检测,发现倍性和环境效应都会对香港牡蛎幼虫生长产生显著影响(p<0.001),环境是影响幼虫存活率及变态的主要因子(p<0.05)。 相似文献
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太平洋牡蛎多倍体研究 总被引：6，自引：0，他引：6
本文综述了太平洋牡蛎多倍体产生的途径、诱导方法、诱导结果、诱导机制、倍性鉴别方法、繁殖、生长、生理指标、抗逆性和口味等。提出：６－ＤＭＡＰ诱导牡蛎三倍体的技术前景广阔;四倍体与二倍体杂交的方法是产生三倍体的最好途径;四倍体是生物方法产生三倍体的中间材料,可以存活,应加大力度地研究和开发;三倍体的性腺能够发育,并可产生具有繁殖力的配子;在良好的环境里,四倍体的生长和抗逆性较二倍体优势;在繁殖季节,三 相似文献
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探讨多倍体牡蛎的遗传基础,通过染色体计数法对2龄杂交三倍体太平洋牡蛎(Crassostrea gigas)群体的染色体数目组成进行了分析,发现在80个具良好中期分裂相的牡蛎中,有56个三倍体(70.0%);12个非整倍体(15.0%),4个2n/3n嵌合体(5.0%);8个二倍体(10.0%)。12个非整倍体中包括9个29条染色体的亚三倍体(3n-1)和3个31条染色体的超三倍体(3n 1)。非整倍体与三倍体的生长差异不明显(P>0.05)。可能由于数量较少的原因,嵌合体和二倍体的生长没有表现明显生长滞后(P>0.05)。 相似文献
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栉孔扇贝三倍体与二倍体的生长比较 总被引：8，自引：0，他引：8
近几年在我国栉孔扇贝养殖业中出现了单产降低、品质下降、大面积死亡问题 ,其主要原因是缺少生长快、品质优、抗逆能力强的养殖新品种。对于养殖贝类来说 ,性成熟往往导致生长抑制、抗逆性下降和肉质下降。目前广泛开展的多倍体贝类研究的主要目的是产生不育的三倍体 ,充分利用三倍体的不育性和生长优势 ,为海水养殖业健康、稳定、持续地发展提供技术支持。通过对栉孔扇贝三倍体和二倍体的生长比较 ,证实栉孔扇贝三倍体具养殖实用价值。１材料与方法１．１材料栉孔扇贝Ｃｈｌａｍｙｓ(Ａｚｕｍａｐｅｃｔｅｎ) ｆａｒｒｅｒｉ取自青岛太平… 相似文献
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盘鲍三倍体及二倍体生长的比较 总被引：5，自引：0，他引：5
在室内工厂化养殖条件下 ,于 1 997年 1 0月对正常盘鲍二倍体个体及用细胞松驰素 B诱导法获得的盘鲍三倍体群的生长情况进行了比较。结果表明 :(1 )在育苗期的 1 4月龄内 ,盘鲍的三倍体群与二倍体个体间在生长上无明显差异 ;(2 ) 1 4月龄后盘鲍的三倍体群与二倍体个体间在生长上出现分化。两周龄的盘鲍三倍体群在壳长和体重上分别比二倍体个体大 1 4.76 %和5 0 .1 9%;两周龄半的盘鲍三倍体群在壳长和体重上分别比二倍体个体大 2 0 .0 0 %和 41 .89%;(3 )如按 6 cm壳长作为商品盘鲍的标准 ,则盘鲍三倍体群只需养殖 2 6个月 (包括育苗期 )即可达到商品盘鲍的标准 ,而二倍体个体则需养殖 3 0个月 (包括育苗期 )。由此可见 ,三倍体商品盘鲍比二倍体商品盘鲍在养殖时间上可缩短 4个月 ;(4)盘鲍三倍体群与二倍体个体群的氨基酸组分相同 ,但盘鲍三倍体群的氨基酸总量比二倍体个体的氨基酸总量高。 相似文献
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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
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Phylogenetic diversity and phenotypic characterization of cultivable bacterioplankton isolated from polar oceans 总被引：1，自引：0，他引：1
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. 相似文献
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Sediment properties, such as water content and density, have been used to estimate the dry and wet weights, as well as the volume of sediment recovered and discharged, during benthic impact experiments conducted in the Pacific and Indian Oceans. The estimates show that the weights of dry (355-1332 t) and wet sediment (1651-4888 t) recovered during the experiments, are not only a function of the total duration and distance covered during the experiment, but also depend on water content and density of the sediment. Estimation of dry sediment and its volumetric ratio in the discharge, are key parameters for calculating the discharged volume. The estimated volume of wet sediment recovered (1427-4049 m 3 ) as well as discharged (2693-6951 m 3 ) during the experiments, provide important inputs to evaluate the sediment resettlement and migration. Using these estimates, the average depth of excavation on the seafloor, can also been calculated. However, the stages of sediment recovery and discharge are expressed differently in some of the experiments. In order to standardize these, different stages have been identified, and definitions of certain terms have been suggested, for use in the future. The methods of calculating different properties, as well as weight and volume of discharged sediment are described in the paper for use in other applications concerning deep-sea discharges. 相似文献
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A vertically integrated model has been used to study the tidal circulation and currents in the Gulf of Kachchh along the west coast of India. The model is fully nonlinear and uses a semiexplicit finite difference scheme to solve the basic hydrodynamic equations on a staggered grid. The model is forced by prescribing the tides along the open boundary of the model domain. The flow is simulated both with and without the presence of the proposed tidal barrage across the Hansthal Creek in the Gulf of Kachchh. The results show a considerable change in the behavior of the tidal flow in the presence of the barrage. 相似文献
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利用中国GF-3卫星SAR和HY-2A卫星微波散射计的首次台风联合定量观测 总被引：4，自引：0，他引：4
<正>The typhoon,as a mature tropical cyclone that develops in the western part of the North Pacific Ocean with high wind speed and heavy rainfall,is one of the most lethal and costly of natural disasters for the densely populated countries of East Asia.It can be easily detected by space-borne sensors operated at microwave,visible or infrared bands(Liu et al.,2014).Synthetic Aperture Radar(SAR)is 相似文献
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Soil core samples fromRhizophora mangleL. andAvicennia schauerianaStapf & Leech forests from south-eastern Brazil were analysed for their total organic matter content and their sugars, amino acid and amino sugars composition. Organic carbon and nitrogen contents were higher inAvicenniathan inRhizophorasoils. The contribution of sugars and amino acids to the total organic carbon pool was constant with depth inRhizophorasoils whereas inAvicenniasoils it increased. Spectral distribution of sugars and amino acids showed a dominance of Ca-affine monomers, particularly acidic amino acids, and the sugar arabinose. Biogeochemical indicators derived from ratios of individual sugar and amino acid monomers confirm previous studies which showed that organic matter in both soils is mainly of mangrove origin. The results further suggest accumulation of organic matter inRhizophorasoils and a continuing degradation of organic matter inAvicenniasoils. The latter may thus release more nutrients to adjacent ecosystems thanRhizophorasoils. 相似文献
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《African Journal of Marine Science》2013,35(1):181-203
Orange roughy Hoplostethus atlanticus are unusual fish. They form dense aggregations that have fuelled lucrative fisheries at great depths (600–1 400 m), especially off Namibia, New Zealand and Australia. They are thought to be very long-lived (>100 years, maturity at 22 – 40 years), and to have exceptionally low natural mortality (M = 0.045–0.064 year?1) and slow growth rates (K = 0.055–0.070 year?1). In addition, they spawn large eggs and have low fecundity. These factors combine to make orange roughy highly susceptible to overfishing; most stocks are below 30% of pristine levels. Assessments are obtained from indices of catch rate and trawl, acoustic and egg surveys. Acoustic estimates are the most direct, but are confounded by the species' low target strength (?50 to ?53 dB)–attributable to the wax-filled swim bladder. Extracellular wax esters are stored in abundance and comprise mostly mono-unsaturated fatty acids, with low concentrations of the ω-3 fatty acid family. This unusual composition (resultant from the species' diet) ensures neutral buoyancy. Stock separation has been inferred mainly from biological studies, but genetic studies have also found differences among stocks within New Zealand and Australia. Deep-water habitat may be damaged by trawling operations and may take many years to recover, so in some quarters there is a call for a portion of suitable habitat to be set aside for preservation. Although Namibian orange roughy are shallower, smaller and younger than those in other stocks, the Namibian fishery sustained high catches for only a few years before quotas were reduced, from 12 000 to 1 875 tons. Three management lessons are suggested for developing orange roughy fisheries based on the Namibian experience: (1) imposition of catch limits during exploratory fishing; (2) starting the acoustic surveys earlier in the fishery, if possible; (3) greater reliance on trends in catch rate until a survey series has been established. 相似文献