栉江珧同工酶多态性的分析

采用垂直板聚丙烯酰胺梯度凝胶电泳对栉江珧(Atrina pectinata Linnaeus)消化盲囊进行了5 种酶(SOD、EST、MDH、ME、LDH) 的同工酶分析。结果表明不同个体的同工酶表达呈现多态现象,个体间酶带带型既有相一致的共同特征谱带,又有较多的变异,5种酶均可把样品大致区分为差异明显的2 种或3 种类型,而且酶谱类型与形态类型基本对应,同工酶表达上的多样性表明栉江珧种内在生化遗传上存在较大的变异, 具有较丰富的遗传多态性。

影响‘尤力克’柠檬不定芽发生主要因素的研究

国家自然科学基金资助项目(30070528)

水生动物虹彩病毒的分子生物学

国家自然科学基金 (3 0 170 72 6); “863”项目 (2 0 0 1AA62 60 3 0 ); 中国科学院方向性创新项目 (2 2 0 3 13 )资助

几种鲟鱼基因组大小、倍体的特性及鲟形目细胞进化的探讨

采用Feulgen-显微分光光度计方法，以鸡红细胞为标准DNA（3．22pg／2C）测定了长江白鲟、达氏鲟、中华鲟、史氏鲟和北美匙吻鲟的体细胞基因组大小（DNA含量）。结果表明，上述五种鲟鱼DNA含量分别为4.11、8．26、9.07、6.07和3．96Pg。长江白鲟和北美匙吻鲟均属于四倍体鱼类，分布在长江水系的中华鲟和达氏鲟两种鲟属鱼类为八倍体类型。史氏鲟初步判断为八倍体。据分析可能存在四倍体的类型。根据所得到的结果并结合已发表的DNA含量和染色体资料，分析了鲟形目鱼类在细胞遗传上的进化特点。鲟形目鱼类

白鲫(♀)×红鲫(♂)异源四倍体鱼的倍性操作及其生殖力的研究

采用热休克调控技术诱导出103尾第一代白鲫（♀）×红鲫（）异源四倍体鱼，并对其生殖力进行了研究。1或2龄的四倍体雄鱼能产生精子，而雌鱼不能产生正常的卵。将异源四倍体雄鱼与二倍体白鲫雌鱼交配产生倍间三倍体鱼，染色体检查证明是整三倍体（3N＝150），但其受精率很低（11．4—51．3％，平均32．4％）．网箱养殖结果表明，倍间三倍体白鲫的生长速度比白鲫快30％以上，雌雄均不育．并用冷休克处理回收异源四倍体4N（）×白鲫2N（♀）受精卵的第二极体产生了新的四倍体鱼．文中还对第一代异源四倍体鱼的批量生产、生殖能

中华双腔吸虫（Dicrocoelium Chinensis Tang et Tang，1978）（Trematoda：Digenea）卵子发生的超微结构研究

利用透射电镜技术观察了中华双腔吸虫（ＤｉｃｒｏｃｏｅｌｉｕｍｃｈｉｎｅｎｓｉｓＴａｎｇｅｔＴａｎｇ，１９７８）的卵巢结构和卵子发生过程，同时提出了划分复殖吸虫卵子发生过程的标准，总结了复殖吸虫卵子发生的一般规律以及中华双腔吸虫卵子发生的特有特征。此外比较分析了不同复殖吸虫的皮质颗粒特征，指出它在分类上可能有重要意义。中华双腔吸虫卵巢和卵子发生的超微结构与大多数复殖吸虫相似，但其卵巢中的各生殖细胞间有网状片层结构及一些颗粒、膜状碎片等支持和营养结构，还有退化的成熟卵母细胞。中华双腔吸虫的卵子发生分为卵原细胞

鲮鱼和二代混精鲮鱼低温耐受能力的差异

采用LKB循环冷却装置以程序降温方式比较鲮鱼及二代混精鲮鱼(草鱼混精鲮或多精混精鲮再用草鱼精液进行混精受精所得子代)的耐寒性能。无论是在7.0℃条件下的耐受时间,还是对低温耐受的极限,二代混精鲮鱼均优于鲮鱼,但这种改善是有限的。作者认为,混精受精法不能从根本上解决鲮鱼的不耐寒性能。应该寻求其他更有效的育种途径。

鲮鱼混精授精的育种试验

1979至1982年间,用瓦氏雅罗鱼、草鱼、链鱼、鲤鱼中的一种或多种精液同鲮鱼新鲜精液混合对鲮鱼成熟卵授精,使其发育成苗,并培育成鱼种。经养殖表明,有几组混精授精得到的鲮鱼,其抗寒性能比不混精授精的鲮鱼强;其中以四种混合精液授精以得混精鲮的耐寒能力最高。现将耐寒能力低达 5.5℃的混精鲮鱼选出,供进一步选育用。最后,根据各组试验结果,提出进一步工作的意见。

Analysis of genetic diversity in Glyptosternum maculatum (Sisoridae, Siluriformes) populations with AFLP markers

We determined the genetic diversity of geographic populations from three spawning grounds (Nyang River, Lhasa River, Shetongmon Reach of Yarlung Zangbo River) of Glyptosternum maculatum with amplified fragment length polymorphism (AFLP) markers. Five primer combinations detected 332 products, 51 of them (15.4%) were polymorphic in at least one population. The Shetongmon population was found to be the richest in genetic diversity as was indicated by the percentage of polymorphic loci and heterozygosity, followed by the Nyang population and the Lhasa population. The pair-wise genetic distance between populations were all very close, ranging from 0.0015 to 0.0042 with an average of 0.0024. The genetic distance was not proportional to the geographic distance. The analysis of molecular variance demonstrated that all variation occurred within populations. The average estimated fixation index (F (st)) of three populations across all polymorphic loci was -0.0184, indicating the absence of genetic differences among the three sampled populations. The differentiation among populations was not significant, and population structure was weak. Our observations will help identify the genetic relationship among populations as the first approach to understand the genetic diversity of Glyptosternum maculatum.

Effects of constructed wetland system on the removal of dibutyl phthalate (DBP)

Phthalic acid esters (PAEs) have become widely diffused in the environment via the manufacturing process. Numerous experiments have shown that the bioaccumulation of PAEs occurred in the aquatic and terrestrial food chain; meanwhile, it was found that some of PAEs were considered as potential carcinogens, teratogens and mutagens. In this research, two vertical/reverse-vertical flow constructed wetland systems were set up to study its removal efficiency of dibutyl, phthalate (DBP) pollution. The results showed that the constructed wetland system could remove DBP effectively, and the removal rates reached nearly 100%. Substrate microorganism and enzymatic activities probably played key roles during DBP removal, and the removal of DBP probably mainly took place in the upper layer of chamber A in the constructed wetland systems. (C) 2007 Elsevier GmbH. All rights reserved.

Removal of dibutyl phthalate by a staged, vertical-flow constructed wetland

Two sets of small scale systems of staged, vertical-flow constructed wetlands (VFCW) were operated in a greenhouse to study the purification of dibutyl phthalate (DBP) in admeasured water. Each system consisted of two chambers in which water flowed downward in chamber I and then upward in chamber 2. The systems were intermittently fed with wastewater under a hydraulic load of 420 mm(.)d(-1). The measured influent concentrations of DBP in the experimental system were 9.84 mg(.)l(-1), while the other system was used as a control and received no DBP. Effluent concentrations of the treated system averaged 5.82 mug(.)l(-1) and were far below the Chinese DBP discharge standard of less than or equal to0.2 mg(.)l(-1). These results indicate the potential purification capacity of this new kind of constructed wetland in removing DBP from a polluted water body.

Effect of natural dissolved humic material on bioavailability and acute toxicity of fenpropathrin to the grass carp, Ctenopharyngodon idellus

The effects of aquatic humic acids on the bioconcentration and acute toxicity of fenpropathrin were evaluated using grass carp, Ctenopharyngodan idellus, in laboratory freshwater systems. The results demonstrated that both bioavailability and acute toxicity decreased in the presence of aquatic humic acid 5 and 10 mg/liter. In addition, the extent of influence increased with increasing concentration of aquatic humic acid, (C) 1999 Academic Press.

Preferential orientation growth of AIN thin films on Si (111) substrates by LP-MOCVD

Aluminum nitride (AIN) thin films were deposited on Si (111) substrates by low pressure metalorganic chemical vapor deposition system. The effects of the V/III ratios on the film structure and surface morphology were systematically studied. The chemical states and vibration modes of AIN films were characterized by X-ray photoelectron spectroscopy and Fourier transform infrared spectrometer. The optical absorption property of the AIN films, characterized by ultraviolet-visible-near infrared spectrophotometer, exhibited a sharp absorption near the wavelength of 206 mm. The AIN (002) preferential orientation growth was obtained at the V/III ratio of 10,000 and the preferential growth mechanism is presented in this paper according to the thermodynamics and kinetics process of the AIN growth.

The field emission properties of nonpolar a-plane n-type GaN films grown on nano-patterned sapphire substrates

Si-doped nonpolar a-plane GaN films were grown on nanopatterned sapphire substrates by a low-pressure metal organic chemical vapor deposition (MOCVD) system. The structure, morphology and field emission properties of the sample were studied by means of high-resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM), and field emission measurement. The XRD analysis shows that the sample is a nonpolar a-plane (11 (2) over bar0) GaN film. The field emission measurement shows that the nonpolar GaN films exhibit excellent field emission properties with a threshold emission field of as low as 10 V/mu m at a current density of 0.63 mu A/cm(2), and a high field emission current density of 74 mA/cm(2) at an applied field of 24 V/mu m. Moreover, the Fowler-Nordheirn plot of the sample fits a near linear relation. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Dielectric relaxation and giant dielectric constant of Nb-doped CaCu3Ti4O12 ceramics under dc bias voltage

CaCu3Ti(4-x)Nb(x)O(12) (x = 0, 0.01, 0.08, 0.2) ceramics were fabricated by a conventional solid-state reaction method. The ceramics showed the body-centered cubic structure without any foreign phases and the grain size decreases with Nb doping. Two Debye-type relaxations were observed for the Nb-doped samples at low frequency and high frequency, respectively. The complex electric modulus analysis revealed that the surface layer, grains and grain boundaries contributed to the dielectric constant. The low-frequency dielectric constant relative to the surface layer decreased to a minimum and then increased with the dc bias voltage at 100 Hz, which were well explained in terms of a model containing two metal oxide semiconductors in series, confirming the surface layer in the ceramics. The shift voltage V-B corresponding to the minimal capacitance increased with increase of the composition x. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.