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1.
17α-甲基睾酮刺激鲻鱼精子发生机制的初步研究   总被引:7,自引:0,他引:7  
在非繁殖季节,将17α-MT混入颗粒饵料,饲喂性腺未成熟的鲻鱼,对照组喂含酒精饵料,每日投饵一次,连续6周。研究结果表明:(1)实验后第二周,实验组有少数鱼轻压鱼腹可见少量精液流出,随后阳性率逐周提高,第五周达到高峰,其后持续较恒定水平。(2)激素处理组释精雄鱼的生殖指数大于不释精雄鱼,也大于对照组。(3)鲻鱼睾丸组织学切片看出,17α-MT处理的释精和不释精雄鱼精细管中各级生精细胞均处于生精活动的旺盛时期,而对照组精细管中充满精原细胞;另外,释精和不释精雄鱼的间质细胞的核的体积和数量都大于和多于对照组。因此,我们认为17αMT可刺激精原细胞增殖、精母细胞成熟分裂和精子形成。  相似文献   

2.
梭鱼(Mugil So-iny)属海产经济鱼类,产卵于海中,亦能进入咸淡水或淡水中生活。 六十年代以来,随着鲻科鱼类养殖在世界范围内的迅速推广,人工繁殖研究已引起普遍的重视。到目前为止,海水和咸淡水养殖的鲻鱼和梭鱼中,鲻鱼(Mugil cephalus)的人工繁殖已达数十万尾种苗的水平,梭鱼也已达数万尾水平。而淡水池塘和水库中混养梭鱼,日益获得推广。共中就天津市郊区来说,目前已有四千余亩水面混养了梭鱼,并取得亩产增产20—100斤梭  相似文献   

3.
海产鱼类中,鲻科Mugilidae鱼类为养殖的良好品种。赤眼梭Liza so-iuy(Basislewsky)即为其中之一。我国北方地区,养殖赤眼梭已有悠久的历史,至少有两百余年。这种鱼生活力强,适盐性广,于淡水以至盐度为34‰的海水中,均能生长。其饵料  相似文献   

4.
报道珠江河口近岸池塘酯、鲷、鲻等在的养殖概貌,主要病害的流行情况及其防治方法。可口近岸池养鱼类的病害明显具有淡水、海水两个区系的病原体;轮养、混养是解决病害发生、蔓延的生态防治措施之一;生活于海水的鱼类对有机磷等农药类较敏感,地重金属类药具有较强的耐药性。  相似文献   

5.
台湾乌鱼子     
在台湾访问期间的多次宴会上,我吃到了颜色黄褐色肥美的乌鱼子,味道清香可口。台湾乡亲介绍说:“这是闻名中外的台湾名特产,是海中奇珍”。乌鱼是台湾名产,学名鲻鱼,头背和体侧颜色黑灰色,腹部银白色,在水里只能看到乌黑的影子,故俗名乌鱼。乌鱼的肉嫩,味道鲜美,且有营养价值。东南沿海江湖均有产鲻鱼。明代孙文恪有“家在越州东近海,鲻鱼肥美胜鲈鱼”之句。鲻鱼生息在  相似文献   

6.
研究了在人工条件下,鲻鱼MugilcephalusLinnaeus幼体各部分形态、器官的发育时间、行为、营养和变态特点,划分了发育期。仔鱼在生长过程常因畸形、损伤和消化不良而死亡;生长差异则存在于整个发育期,并且差异随时间延长而增大。同时,对鲻鱼早期发育的生物学特点、疾病、变态危险期和生长差异等进行了讨论,指出鲻鱼与环境和饲育条件之间的生态生理关系,以及这种关系对鲻鱼生长和存活的影响。  相似文献   

7.
鲻鱼精子发生的组织学研究   总被引:7,自引:0,他引:7  
林君卓  翁幼竹  方永强  洪万树 《台湾海峡》2001,20(1):57-60,T002
本文报道用组织学方法研究了不同季节鲻鱼的精巢结构和精子发生过程。结果表明,鲻鱼精巢属于叶状结构。根据精子发生的特点,分为5个时期:精原细胞增殖期、初级精母细胞期、次级精母细胞期、精子形成期和精子成熟期。依雄性鲻鱼精子发育和成熟的季节来看,厦门鲻鱼繁殖季节为每年11-12月,系一次性排精类型。文中详细描述各级生精细胞的特征,并讨论了Sertoli细胞在精子发生中的生理作用。  相似文献   

8.
人工培育条件下鲻鱼早期发育的生理生态研究   总被引:8,自引:0,他引:8  
研究了在人工条件下,鲻鱼Mugil cephalus Linneus幼体各部分形态,器官的发育时间、行为、营养和变态特点,划分了发育期。仔鱼在生长常因畸形,损伤和消化不良而死亡;生长差异则存在于整个发育期,并且差异随时间延长而增大,同时,对鲻鱼早期发育地生物学特点,疾病、变态危险期和生长差异等进行了讨论,指出鲻鱼与环境和饲育条件之间的生态生理关系,以及这种关系对鲻鱼生长和存活的影响。  相似文献   

9.
我国没有头鲻Mugil cephalus Linnaeus,现今国内描述的头鲻,实为鲻鱼,应予更正。鲻鱼Mugil oeur Forskal存在变异个体,主要变异是第一背鳍Ⅲ棘,而正常个体Ⅳ棘。  相似文献   

10.
采用PHA体内注射──空气干燥制片法初步研究了5种海水鱼类的染色体。核型公式分别为鲻鱼、鲈鱼和黄姑鱼2n=48t,NF=48,其中鲻鱼的t1染色体、鲈鱼的t12染色体及黄姑鱼的t3染色体均为具明显次缢痕染色体,矛尾复虎鱼2n=44,2m+42st、t,NF=46,其t18染色体为具次缢痕染色体;绿鳍马面2n=40t,NF=40,其中t14染色体具次缢痕。  相似文献   

11.
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.
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   

13.
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   

14.
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   

15.
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.  相似文献   

16.
《海洋学报(英文版)》2014,(8):F0003-F0003
<正>Acta Oceanologica Sinica(AOS)is a comprehensive academic journal edited by the Editorial Committee of Acta Oceanologica Sinica and is designed to provide a forum for important research papers of the marine scientific community which reflect the information on a worldwide basis.The journal publishes scholarly papers on marine science and technology,including physics,chemistry,biology,  相似文献   

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This article presents a methodology developed to evaluate the instability of submarine slopes that extend over a large area. Special attention was paid to (1) the complex geometry (bathymetry) and the expanse of the slope, (2) the heterogeneity of the sediment, and (3) the distribution of the pore pressure. The safety factor was considered as a spatially varying quantity. The General Formulation (GLE, Fredlund and Krahn 1977), which fully satisfies equilibrium conditions, was used for evaluating the stability of the marine slope. The submarine slope failure, which occurred on 16 October 1979 during the construction of the new Nice airport, was studied in order to test the developed model. Geotechnical parameters were taken from experimental tests carried out by IFREMER on 19 cores extracted at different depths (from 27 m to 1300 m) (Cochonat, Bourillet, and Savoye, 1993; Mulder et al., 1994). Many scenarios were proposed in order to explain the cause of the Nice slope failure (Habib, 1994). In this article, two of those scenarios were tested. Simulation results are presented and discussed.  相似文献   

20.
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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