Characterization and expression analysis of TNF-related apoptosis inducing ligand (TRAIL) in grass carp Ctenopharyngodon idella

TRAIL (Apo2 ligand) described as a type II transmembrame protein belonging to the TNF superfamily can induce apoptotic cell death in a variety of cell types. In the present study, a putative cDNA sequence encoding the 299 amino acids of TRAIL (GC-TRAIL) and its genomic organization were identified in grass carp Ctenopharyngodon idella. The predicted GC-TRAIL sequence showed 44 and 41% identities to chicken and human TRAILs, respectively. In a domain search, a tumor necrosis factor homology domain (THD) was identified in the C-terminal portion of TRAILs. The GC-TRAIL gene consists of five exons, with four intervening introns, spaced over approximately 4 kb of genomic sequence. Analysis of GC-TRAlL promoter region revealed the presence of a number of putative transcription factor binding sites, such as Sp1, NF-kappaB, AP-1, GATA, NFAT, HNF, STAT, P53 and IRFI sequences which are important for the expression of other TNF family members. Phylogenetic analysis placed GC-TRAIL and the putative zebrafish (Danio rerio) TRAIL obtained from searching the zebrafish database into one separate cluster near mammalian TRAIL genes, but apart from the reported zebrafish TRAIL-like protein, indicating that the GC-TRAIL is an authentic fish TRAIL. Expression analysis revealed that GC-TRAIL is expressed in many tissues, such as in gills, liver, trunk kidney, head kidney, intestine and spleen. (c) 2005 Elsevier B.V. All rights reserved.

Molecular cloning of TRAF2 binding protein gene and its promoter region from the grass carp Ctenopharyngodon idellus

A tumor necrosis factor receptor-associated factor 2 binding protein (T2BP) gene was isolated from the grass carp (Ctenopharyngodon idellus) by utilizing suppression subtractive hybridization (SSH) and rapid amplification of cDNA ends (RACE). The grass carp T2BP (GT2BP) gene contains an open reading frame of 579 nucleotide(s) (nt), encoding 193 amino acids, with 23 nt 5'-untranslated region and a long 3'-untranslated region of 434 nt including poly (A), 1 AUUUA motif and 4 AUUUUA motifs. No signal peptide has been detected in the predicted GT2BP, but a characteristic forkhead associated domain is present. The GT2BP mRNA shares 83% identity with the zebrafish DNA sequence, and they both have no introns in the genomic DNA. The putative transcription factor binding sites of GT2BP include two C/EBP alpha binding sites, and one c-Jun binding, one AP-1 binding, and one nuclear factor kappa B (NF kappa B) binding sites. Southern blot analysis revealed that the GT2BP was a single-copy gene. Individual difference was observed in GT2BP expression in examined organs of healthy grass carp. However, the expression of GT2BP in all examined organs in a fish with the highest copepod infection level and the significantly higher expression level in spleen and liver in infected fish may indicate its up-regulation with the parasite infection. (c) 2005 Elsevier B.V. All rights reserved.

Structure of the phytoplankton community and its relationship to water quality in Donghu Lake, Wuhan, China

The phytoplankton community structure, in terms of species composition, total standing crop, and abundance of the dominant algal species, at four stations in Donghu Lake, Wuhan, China, was investigated monthly from January 1994 to December 1996. A total of 260 taxa was observed, of which Chlorophyta (106 taxa) contributed the highest portion of the total number of taxa, followed by Bacillariophyta (82 taxa) and Cyanophyta (32 taxa). The total standing crop measured by means of chlorophyll a content, cell density, and cell biovolume, as well as the abundance of the dominant species, declined in the order of Station I to Station IV. Seasonal changes of the standing crop varied greatly among the four stations. Although the cell density at the four stations showed a single peak within a year, the peak density varied from July to November, dependent on the sampling year and the station. For chlorophyll a content and cell biovolume, multiple peaks were observed at Stations I and II, but a single peak was found at Stations III and IV. The phytoplankton community structure indicated that the trophic status was the highest at Station I (most eutrophic), followed by Station II; Stations III and IV were the least trophic areas. The long-term changes in phytoplankton community structure further suggested that changes in phytoplankton community structure were correlated with water quality, and eutrophication of Donghu Lake had been aggravated since the 1950s.

Expression and molecular analysis of phbB gene in Chlamydomonas reinhardtii

The expression vector containing phbB and ble genes was constructed and transformed into cell-wall-deficient strain Chlamydomonas reinhardtii CC-849 by the glass-head method. The transgenic alga was selected and maintained in the TAP agar plates containing 10 mug/mL Zeomycin. Transgenic alga, which could express phbB at the transcriptional level, was obtained and further confirmed with PCR, Southern blot and RT-PCR-DNA hybridization analysis.

Role of interface dipole in metal gate/high-k effective work function modulation by aluminum incorporation

The interface dipole and its role in the effective work function (EWF) modulation by Al incorporation are investigated. Our study shows that the interface dipole located at the high-k/SiO2 interface causes an electrostatic potential difference across the metal/high-k interface, which significantly shifts the band alignment between the metal and high-k, consequently modulating the EWF. The electrochemical potential equalization and electrostatic potential methods are used to evaluate the interface dipole and its contribution. The calculated EWF modulation agrees with experimental data and can provide insight to the control of EWF in future pMOS technology.

Influence of the cavity on the low-temperature photoluminescence of SiGe/Si multiquantum wells grown on a silicon-on-insulator substrate

The influences of the cavity on the low-temperature photoluminescence of Si0.59Ge0.41/Si multiquantum wells grown on silicon-on-insulator substrates are discussed. The positions of the modulated photoluminescence (PL) peaks not only relate to the nature of SiGe/Si multiquantum wells, but also relate to the characteristic of the cavity. With increasing temperature, a redshift of the modulated PL peak originating from the thermo-optical effect of the cavity is observed.

Electronic structures of wurtzite ZnO and ZnO/MgZnO quantum well

The band structures of wurtzite ZnO are calculated using the empirical pseudopotential method (EPM). The 8 parameters of the Zn and O atom pesudopotential form factors with Schluter's formula are obtained. The effective mass parameters are extracted by using k.p Hamiltonian to fit the EPM results. The calculated band edge energies (E-g, E-A, E-B, and E-C) at Gamma point are in good agreement with experimental results. The ordering of ZnO at the top of valence band is found to be A(Gamma(7))-B(Gamma(9))-C(Gamma(7)) due to a negative spin-orbit (SO) splitting. Based on the band parameters obtained, the valence hole subbands of wurzite ZnO/MgxZn1-xO tensile-strained quantum wells (QWs) with different well widths and Mg compositions are calculated using 6-band k.p method. (c) 2005 Elsevier B.V. All rights reserved.

Highly efficient and tunable microlasers on photonic crystal slab

zhangdi于2010-03-09批量导入

Experimental investigation of slow light phenomenon in photonic crystal waveguide line defect laser

The guide mode whose frequency locates in the band edge in photonic crystal single line defect waveguide has very low group velocity. So the confinement and gain of electromagnetic field in the band edge are strongly enhanced. Photonic crystal waveguide laser is fabricated and the slow light phenomenon is investigated. The laser is pumped by pulsed pumping light at 980nm whose duty ratio is 0.05%. The active layer in photonic crystal slab is InGaAsP multiple quantum well. Light is transimited by a photonic crystal chirp waveguide in one facet of the laser. Then the output light is coupled to a fiber and the character of laser is analysis by an optical spectrometer. It is found that single mode and multimode happens with different power of pumping light. Meanwhile the plane wave expansion and finite-difference time-domain methods are used to simulate the phenomenon of slow light. And the result of the experiment is compared with the theory which proves the slow light results in lasing oscillation.

Magnetic resonant cavity composing of a three layered plasmonic nanostructure

The magnetic-type plasmon resonant of a metal-dielectric-metal nanocavity working at the wavelength of 1.55 mu m is explored, in which the upper layer is periodically patterned with metallic nanostrip arrays. In the dielectric film layer, the magnetic energy intensity is enhanced about 1700 times when irradiated with a p-polarized plane wave. We numerically studied the dispersion of the modes and the Q-value of this periodic cavity arrays. Q value is estimated about 18 and still has room for further improvement. It provides a new type of nanocavity that exhibits a strong magnetic response.

Electronic structures of wurtzite ZnO and ZnO/MgZnO quantum well

The band structures of wurtzite ZnO are calculated using the empirical pseudopotential method (EPM). The 8 parameters of the Zn and O atom pesudopotential form factors with Schluter's formula are obtained. The effective mass parameters are extracted by using k.p Hamiltonian to fit the EPM results. The calculated band edge energies (E-g, E-A, E-B, and E-C) at Gamma point are in good agreement with experimental results. The ordering of ZnO at the top of valence band is found to be A(Gamma(7))-B(Gamma(9))-C(Gamma(7)) due to a negative spin-orbit (SO) splitting. Based on the band parameters obtained, the valence hole subbands of wurzite ZnO/MgxZn1-xO tensile-strained quantum wells (QWs) with different well widths and Mg compositions are calculated using 6-band k.p method. (c) 2005 Elsevier B.V. All rights reserved.

Simultaneous multiwavelength observations of sagittarius A

We observed Sgr A* using the Very Large Array (VLA) and the Giant Metrewave Radio Telescope (GMRT) at multiple centimeter and millimeter wavelengths on 2003 June 17. The measured flux densities of Sgr A*, together with those obtained from the Submillimeter Array (SMA) and the Keck II 10 m telescope on the same date, are used to construct a simultaneous spectrum of Sgr A* from 90 cm to 3.8 mu m. The simultaneous spectrum shows a spectral break at about 3.6 cm, a possible signature of synchrotron self-absorption of the strong radio outburst that occurred near epoch 2003 July 17. At 90 cm, the flux density of Sgr A* is 0.22 +/- 0.06 Jy, suggesting a sharp decrease in flux density at wavelengths longer than 47 cm. The spectrum at long cm wavelengths appears to be consistent with free-free absorption by a screen of ionized gas with a cutoff similar to 100 cm. This cutoff wavelength appears to be three times longer than that of similar to 30 cm suggested by Davies, Walsh, & Booth based on observations in 1974 and 1975. Our analysis suggests that the flux densities of Sgr A* at wavelengths longer than 30 cm could be attenuated and modulated by stellar winds from massive stars close to Sgr A*.

黄土高原长期种植苜蓿对土壤硫、钙、镁的影响

以22年定位试验为基础,研究黄土高原长期种植紫花苜蓿(Medicago sativaL.)情况下土壤硫、钙、镁组分的变化。结果表明:长期施P使苜蓿连作耕层土壤总硫、有效硫、水溶性硫、吸附性硫、HCl可溶性硫、总无机硫和有机硫含量分别增加9.41%、62.41%、47.51%、30.07%、2.25%、5.38%和17.54%;长期施NPM使苜蓿连作耕层土壤总硫、有效硫、水溶性硫、吸附性硫、HCl可溶性硫、总无机硫和有机硫含量分别增加20.89%、98.31%、68.44%、57.34%、8.07%、12.54%和37.69%。长期施P使苜蓿连作耕层土壤全钙、有效钙、水溶态钙、交换态钙和酸溶态钙含量增加分别增加4.64%、4.27%、11.66%、4.05%和8.59%,但残余态钙含量降低2.21%;长期施NPM使苜蓿连作耕层土壤全钙、有效钙、水溶态钙、交换态钙和酸溶态钙含量增加分别增加8.69%、8.30%、51.59%、6.73%和27.77%,但残余态钙含量降低26.23%。长期施NPM使苜蓿连作耕层土壤全镁、有效镁、水溶态镁、交换态镁、酸溶态镁和残余态镁含量分别增加7.38%、61.98%、63.16%...

两种土壤水分特征曲线间接推求方法对黄土的适应性评价

土壤水分特征曲线(SWCC)是模拟土壤水分运动和溶质运移的一个重要参数,利用土壤的基本物理性质来间接推求SWCC的方法已经成为当今土壤物理学领域的研究热点。为了比较两种SWCC间接推求方法——Arya-Paris物理经验方法(简称AP方法)和Tyler-Wheatcraft分形几何方法(简称TW方法)对黄土的适应性,该文分析了黄土高原296组土壤颗粒分布、容重和水分特征曲线等资料,利用简化的Fredlund(Fred3P)模型模拟得到连续的土壤颗粒分布曲线,然后应用AP和TW方法预测出相应吸力下的土壤含水量。研究结果表明,对于黄土性土壤,AP和TW两种方法的预测结果均达到了一定的精度,相比较而言AP方法的预测效果明显优于TW方法,且受质地影响小。

非洲爪蟾Nkx6.3在原肠运动和神经嵴诱导调控中的功能及爪蟾神经管腹侧图式形成的研究

神经嵴（neural crest）是一类脊椎动物特有的多潜能迁移细胞。这一类细胞历经“表皮—间充质”转换（EMT），与神经管背侧的其它细胞分离，经由不同路线迁移，定位于胚胎外周各处，后分化为不同的细胞类型包括外周神经系统、颅面骨骼系统及色素细胞等。神经嵴的发育是一个多途径多步骤的过程，受多种信号通路及转录因子调控。这些调控因子相互调节形成精密网络，可被划分为三个主要层次类群：分泌性信号分子（BMP、Wnt、FGF、Delta）、神经板边界特异基因（Msx、Pax3/7、 Zic1、Dlx3/5）、神经嵴特异基因（Snail/Slug、AP-2、FoxD3、Twist、Id、cMyc、Sox9/10）。本文第一章主要概述不同组织来源的各种分泌信号在神经嵴诱导中的作用以及他们之间的整合调控。 Nkx6家族蛋白是一类进化上保守的转录因子，在脊椎动物中枢神经系统（CNS)的图式形成和胰腺的发育中有重要作用。在第二章，我们描述了非洲爪蟾中Nkx6家族基因的克隆及其表达图式。与小鼠和鸡中的同源基因类似，爪蟾的Nkx6家族基因在胚胎发育过程中主要表达于中枢神经系统和前部内胚层组织。其中Nkx6.1和Nkx6.2在神经胚期神经板表达重合，晚期都表达于后脑和脊髓的腹侧。Nkx6.3从卵裂期到神经胚早期都表达于非神经外胚层，而尾芽期表达于后脑后部和腮弓。在内胚层中，Nkx6.2在尾芽期表达于底索。在蝌蚪期，Nkx6家族的三个基因分别表达于前部内胚层的衍生物，包括胰腺、胃、食道和肺。 Nkx6.3是最近发现的Nkx6家族新成员，它在爪蟾中的表达与Nkx6.1和Nkx6.2有了较大分歧。在第三章，我们通过功能获得及功能缺失实验来探讨Nkx6.3在爪蟾早期发育中的功能。我们发现原肠期前过量或抑制Nkx6.3表达都会影响胚胎原肠运动的正常进行。我们通过动物帽延伸实验证明Nkx6.3参与了细胞运动。半定量RT-PCR结果显示，Nkx6.3可以调控一些粘附分子的表达。以上结果说明Nkx6.3通过调控粘附分子的转录而参与细胞运动的调控。我们还发神经嵴（neural crest）是一类脊椎动物特有的多潜能迁移细胞。这一类细胞历经“表皮—间充质”转换（EMT），与神经管背侧的其它细胞分离，经由不同路线迁移，定位于胚胎外周各处，后分化为不同的细胞类型包括外周神经系统、颅面骨骼系统及色素细胞等。神经嵴的发育是一个多途径多步骤的过程，受多种信号通路及转录因子调控。这些调控因子相互调节形成精密网络，可被划分为三个主要层次类群：分泌性信号分子（BMP、Wnt、FGF、Delta）、神经板边界特异基因（Msx、Pax3/7、 Zic1、Dlx3/5）、神经嵴特异基因（Snail/Slug、AP-2、FoxD3、Twist、Id、cMyc、Sox9/10）。本文第一章主要概述不同组织来源的各种分泌信号在神经嵴诱导中的作用以及他们之间的整合调控。 Nkx6家族蛋白是一类进化上保守的转录因子，在脊椎动物中枢神经系统（CNS)的图式形成和胰腺的发育中有重要作用。在第二章，我们描述了非洲爪蟾中Nkx6家族基因的克隆及其表达图式。与小鼠和鸡中的同源基因类似，爪蟾的Nkx6家族基因在胚胎发育过程中主要表达于中枢神经系统和前部内胚层组织。其中Nkx6.1和Nkx6.2在神经胚期神经板表达重合，晚期都表达于后脑和脊髓的腹侧。Nkx6.3从卵裂期到神经胚早期都表达于非神经外胚层，而尾芽期表达于后脑后部和腮弓。在内胚层中，Nkx6.2在尾芽期表达于底索。在蝌蚪期，Nkx6家族的三个基因分别表达于前部内胚层的衍生物，包括胰腺、胃、食道和肺。 Nkx6.3是最近发现的Nkx6家族新成员，它在爪蟾中的表达与Nkx6.1和Nkx6.2有了较大分歧。在第三章，我们通过功能获得及功能缺失实验来探讨Nkx6.3在爪蟾早期发育中的功能。我们发现原肠期前过量或抑制Nkx6.3表达都会影响胚胎原肠运动的正常进行。我们通过动物帽延伸实验证明Nkx6.3参与了细胞运动。半定量RT-PCR结果显示，Nkx6.3可以调控一些粘附分子的表达。以上结果说明Nkx6.3通过调控粘附分子的转录而参与细胞运动的调控。我们还发现，在爪蟾胚胎中Nkx6.3的过表达或抑制表达都导致神经嵴标记基因表达降低。进一步研究发现，32细胞期在不同部位注射Nkx6.3 mRNA可以异位诱导或抑制Slug的表达。动物帽实验显示，Nkx6.3单独过表达可以诱导神经嵴发生，而迄今为止转录因子中只有Snail1具有这一单独诱导能力。在爪蟾胚胎及动物帽中，过表达Nkx6.3都可以诱导Fgf8、Wnt8而抑制BMP4的转录，而且Nkx6.3对这些分泌因子的调控方式是不同的。4细胞期过表达Nkx6.3的胚胎，在促进Fgf8和Wnt8而抑制BMP4的同时，却抑制神经板边界特异基因Msx1、Pax3和神经嵴特异基因Slug的表达，说明Nkx6.3对神经嵴的诱导调控在神经板边界基因层次还存在抑制作用。32细胞过表达Nkx6.3会细胞自主性抑制以及细胞非自主诱导Msx1、Pax3、Slug的表达。Nkx6.3异位诱导Dlx5却抑制Dlx3的表达，说明Dlx5可能是Nkx6.3负调控的直接靶基因。由此，我们提出Nkx6.3的神经嵴诱导调控分为两个层次：分泌信号分子水平的正调控和神经板边界决定水平的负调控。在脊椎动物的神经发生过程中，神经管背腹不同层次形成不同的神经元。这些神经元细胞的命运由背腹起源的多种形态发生素决定。形态发生素通过浓度梯度确定了一组转录因子在神经管背腹不同层次的特异表达，这些基因的组合调控决定了神经前体细胞的命运。然而，这些转录因子是如何解读形态发生素梯度信号的还不是很清楚。第四章，我们通过对神经管腹侧特异表达的转录因子的调控区进行预测，确定了可能调控这些基因表达的保守区段。此外，我们改进了爪蟾转基因操作，并用这一技术确证了Nkx6.2的调控区域。Dbx1、Nkx2.2及Pax6的转录调控区已在小鼠或爪蟾中报道过。由此我们得到了两对在神经管背腹图式中相互作用的转录因子的调控区域：Nkx6.2和Dbx1、Nkx2.2和Pax6。通过对Nkx6.2和Dbx1的调控保守区的转录因子结合位点的预测，我们发现这四个基因以及Wnt信号之间存在大量的相互调控。然而在这两个基因的调控区，我们没有发现Gli的调控位点，暗示这两个基因可能不受Shh的直接调控。我们还克隆了Dbx家族的两个基因，并检测了它们的时空特异性表达，发现Dbx2是母源性表达的，而Dbx1是合子型基因。这两个基因的表达图式相似，都在神经板中线两侧成线状表达，尾芽期在神经管中部表达。过表达Dbx2抑制神经元的初级分化，说明它可能与Dbx1一样具有维持神经板细胞未分化状态的功能。Dbx2的过表达还抑制Nkx6.2及Dbx1的表达，说明它们可能一起参与了神经管腹侧图式的调控。