The molecular characterization of RNA segment S9 of grass carp hemorrhage virus (GCHV), an aquareovirus

Although reovirus infection is one of the major virus diseases of grass carp in China, the available knowledge on the structure and function of genes and proteins of the virus is limited. The complete sequence of the S9 genome segment of grass carp hemorrhage virus (GCHV) was determined. The segment consists of 1130 nucleotides and has a large open reading frame (ORF) encoding a protein of 352 amino acids with predicted molecular mass of 37.7 kDa. Amino acid sequence comparison revealed that the deduced protein encoded by GCHV S9 is closely related to the sigma NS proteins of mammalian reovirus (MRV) and avian reovirus (ARV). Secondary structure analysis displayed that the form of alpha -helices (40.1%) and beta -sheets (49.4%) are the richest two contents in the protein encoded by S9, and this protein is predicted to be a nonstructural protein. (C) 2001 Elsevier Science B.V. All rights reserved.

Determination of trace level microcystins in water using solid-phase extraction and high performance liquid chromatography

This paper presents a method for trace level analysis of microcystins in water using solid-phase extraction and high performance liquid chromatography. The optimized condition enabled the determination of common microcystins at levels as low as 0.02 similar to 0.05 mug/L, and the liner range is from 0.1 mug/L to 50 mug/L. The method has been applied to the analysis of field sample from Dianchi lake.

Comparative extraction of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F-s) from a variety of solid samples

Extraction experiments with spiking of C-13(12)-PCDD/Fs were performed with a variety of PCDD/Fs contaminated samples. The extraction recovery of PCDD/Fs was mainly influenced by PCDD/Fs concentration and the sample matrix. Generally, the first soxhlet extraction with toluene has suitable recovery. From the selected samples, only FAMS4 and 5 which are fly ashes with high concentration, the recovery of the first soxhlet extraction with 24 hr. is low, but PCDD/Fs were almost completely removed after 72 hr. Copyright (C) 1996 Elsevier Science Ltd

PURIFICATION AND CHARACTERIZATION OF A KINASE SPECIFIC FOR THE SERINE-RICH AND ARGININE-RICH PRE-MESSENGER-RNA SPLICING FACTORS

Members of the SR family of pre-mRNA splicing factors are phosphoproteins that share a phosphoepitope specifically recognized by monoclonal antibody (mAb) 104. Recent studies have indicated that phosphorylation may regulate the activity and the intracellular localization of these splicing factors. Here, we report the purification and kinetic properties of SR protein kinase 1 (SRPK1), a kinase specific for SR family members. We demonstrate that the kinase specifically recognizes the SR domain, which contains serine/arginine repeats. Previous studies have shown that dephosphorylated SR proteins did not react with mAb 104 and migrated faster in SDS gels than SR proteins from mammalian cells. We show that SRPK1 restores both mobility and mAB 104 reactivity to a SR protein SF2/ASF (splicing factor 2/alternative splicing factor) produced in bacteria, suggesting that SRPK1 is responsible for the generation of the mAb 104-specific phosphoepitope in vivo. Finally, we have correlated the effects of mutagenesis in the SR domain of SF2/ASF on splicing with those on phosphorylation of the protein by SRPK1, suggesting that phosphorylation of SR proteins is required for splicing.

Improved light extraction of GaN-based LEDs with nano-roughened p-GaN surfaces

p-GaN surfaces are nano-roughened by plasma etching to improve the optical performance of GaN-based light emitting diodes (LEDs). The nano-roughened GaN present a relaxation of stress. The light extraction of the LEDs with nano-roughened surfaces is greatly improved when compared with that of the conventional LEDs without nano-roughening. PL-mapping intensities of the nano-roughened LED epi-wafers for different roughening times present two to ten orders of enhancement. The light output powers are also higher for the nano-roughened LED devices. This improvement is attributed to that nano-roughened surfaces can provide photons multiple chances to escape from the LED surfaces.

Light extraction of GaN LEDs with 2-D photonic crystal structure

Ultraviolet photo-lithography is employed to introduce two-dimensional (2D) photonic crystal (PC) structure on the top surface of GaN-based light emitting diode (LED). PC patterns are transferred to 460-nm-thick transparent indium tin oxide (ITO) electrode by inductively coupled plasma (ICP) etching. Light intensity of PC-LED can be enhanced by 38% comparing with the one without PC structure. Rigorous coupled wave analysis method is performed to calculate the light transmission spectrum of PC slab. Simulation results indicate that total internal reflect angle which modulated by PC structure has been increased by 7 degrees, which means that the light extraction efficiency is enhanced outstandingly.

Extraction of intrinsic frequency response of p-i-n photodiodes

This letter presents a new method for extracting the intrinsic frequency response of a p-i-n photodiode (PD) from the measured frequency response of the PD at different bias voltages. This method is much simpler than the conventional calibration method, since only the measured scattering parameters are required, and there is no need to calibrate the test fixtures and the lightwave source. Experiment shows that the proposed method is as accurate as the calibration method.

Extraction of intrinsic response from S-parameters of laser diodes

We describe a new method for extracting the intrinsic response of a laser diode from S-parameters measured using a calibrated vector network analyzer. The experimental results obtained using the new method are compared with those obtained using the optical modulation method and the frequency response subtraction method. Good agreement has been obtained, confirming the new method validity and accuracy. The new method has the advantages of obtaining the intrinsic characteristics of a laser diode with conventional measurements using a network analyzer.

Wavelet denoising and feature extraction of seismic signal for footstep detection

Seismic sensors are widely used to detect moving target in ground sensor networks. Footstep detection is very important for security surveillance and other applications. Because of non-stationary characteristic of seismic signal and complex environment conditions, footstep detection is a very challenging problem. A novel wavelet denoising method based on singular value decomposition is used to solve these problems. The signal-to-noise ratio (SNR) of raw footstep signal is greatly improved using this strategy. The feature extraction method is also discussed after denosing procedure. Comparing, with kurtosis statistic feature, the wavelet energy feature is more promising for seismic footstep detection, especially in a long distance surveillance.

新外显子的起源与功能及短同源序列介导转录滑动产生嵌合RNA 的研究

新外显子的起源是一种重要的增加转录组和蛋白质组多样性的分子机制。 对于新外显子及其父本基因的进化和功能特征方面还有很多重要的问题有待于 解决。本研究首先在全基因组水平上鉴定在人和小鼠中产生的新外显子，随后 对这些外显子及其父本基因作进化和功能上的分析。我们发现新外显子倾向于 位于基因的UTR 区域，尤其是5’ UTR 区域，这表明可能有些新外显子的出现 与基因的表达调控相关。我们还发现，产生新外显子的基因具有较高的组织表 达特异性，其基因功能倾向于细胞调控和与外界环境相互作用。通过对外群中 直系同源基因的分析，我们的结果表明进化速率较高的基因更容易获得新的外 显子，纠正了先前认为的获得新外显子会加速基因进化速率的看法。 我们对哺乳类CDYL 基因家族中产生的新外显子进行了具体的进化分析和 功能研究。我们的结果表明CDYL 基因在哺乳类分化前在原先的基因上游区域 获得了一个新的启动子和三个新的外显子。随后在哺乳动物各个支系的分化中， CDYL 基因在小鼠，狗和人中分别独立的进化出一个新的外显子。同源比对的 结果表明，这些新外显子是通过内含子序列的外显子化这一分子机制产生。近 缘物种间的进化速率的计算结果表明这些新产生的外显子具有快速进化的模 式，并且其快速进化可能是由正选择所驱动。在人中，多种突变包括新外显子 的获得，启动子的改变，选择性剪切的发生使得人的CDYL 基因获得了一种新 的编码更长蛋白质的剪切体。在人Hela 细胞系中的实验表明，新产生的蛋白质 与原有的蛋白质相比都具有显著的转录抑制活性，但新的蛋白质的转录抑制活 性较弱，且两者之间存在相互干扰的关系。这一结果表明通过新外显子的获得 产生的新的蛋白质可以丰富原有的基因表达调控体系，使得生物体的调控网络 更加精确。 嵌合RNA 通常认为是由来源于不同的pre-mRNA 的外显子通过反式剪切连 接在一起形成的。这一现象在包括多种动物和植物中被广泛的报道。我们的研 究首先通过大规模表达序列（ESTs）的搜索，在酵母，果蝇，小鼠和人中鉴定 到了大量的嵌合RNA。这一结果表明形成嵌合RNA 在真核生物中是一种普遍 的生物学过程，是一种重要的增加转录组和蛋白质组的多样性的分子机制。对 嵌合RNA 的序列分析表明，仅有<20%的嵌合RNA 在接合处可以找到典型的剪切位点 GU-AG，可以用经典的反式剪切模型来解释其产生机制。然而有意思的 是，我们在大约一半的嵌合RNA 的供体基因之间找到了短的同源序列，这一发 现使我们提出了一种新的分子机制来解释这些嵌合RNA 的形成，我们称之为 “转录滑动”模型。在酵母我们，我们用实验的方法验证了短同源序列对形成嵌 合RNA 的必要性，有力地支持了我们这一模型。