Allozyme and RAPD variation in the eastern Pacific yellowfin tuna (Thunnus albacares)

Stock structure of eastern Pacific yellowfin tuna was investigated by analyzing allozymes and random amplified polymorphic DNAs (RAPDs) from 10 samples of 20–30 individuals each, collected between 1994 and 1996 from fishing vessels operating in the Inter-American Tropical Tuna Commission (IATTC) yellowfin regulatory area (CYRA). Allozyme analysis resolved 28 loci, eight of which were polymorphic under the 0.95 criterion: Aat-S*, Glud, Gpi-F*, Gpi-S*, La, Lgg, Pap-F*, and 6-Pgd, resulting in a mean heterozygosity over all allozyme loci of H = 0.052. Four polymorphic RAPD loci were selected for analysis, resulting in a mean heterozygosity of H = 0.43. Eight of 45 pairwise comparisons of allozyme allele frequencies among the ten samples showed significant differences after correction for multiple testing (P<0.0001), all of which involved comparisons with the Gulf of California sample. Confirmation of this signal of population structure would have management implications. No significant divergence in RAPD allele frequencies was observed among samples. Weir and Cockerham θ estimated for allozyme loci (θ=0.048; P<0.05) and RAPD loci (θ=0.030; P>0.05) revealed little population structure among samples. Mantel tests demonstrated that the genetic relationships among samples did not correspond to an isolation-by-distance model for either class of marker. Four of eight comparisons of coastal and offshore samples revealed differences of allele frequencies at the Gpi-F* locus (P<0.05), although none of these differences was significant after correction for multiple testing (P>0.001). Results are consistent with the hypothesis that the CYRA yellowfin tuna samples comprise a single genetic stock, although gene flow appears to be greater among coastal samples than between coastal and offshore samples.

软电离质谱在蛋白质组分析和生物活性分子表征中的应用

随着软电离技术的发展，特别是基质辅助激光解析（MALDI）和电喷雾（ESI）两种软电离技术的出现，使质谱分析生物大分子成为可能，将质谱的应用范围迅速扩展到生命科学的诸多研究领域，特别是成为了蛋白质组分析，医学诊断，药物分析等领域不可替代的新工具。首先，采用凝胶电泳与傅立叶变换离子回旋共振质谱（FT-ICR MS）的高分辨率和高质量精确度性能相结合的新方法，对不同肺病患者的支气管肺泡灌洗液进行了快速直接的蛋白质组分析，为肺疾病诊断学、肺病相关机理的研究以及高分辨质谱在蛋白质组分析中的应用奠定了基础。一维（1-D）和二维（2-D）凝胶电泳与高分辨FT-ICR MS相结合，对慢性支气管炎（cblonic broncnitis，CB）和囊泡纤维化（cystic fibrosis，CF）患者的支气管肺泡灌洗液（BALF）中表面蛋白A和D进行了鉴定；并对表面蛋白的翻译后修饰（hydroxy-prollne）进行了直接的确定；对来自于不同肺泡蛋白沉积症（PAP）患者的BALF中的特异性蛋白进行了鉴定，鉴定出表面蛋白A的两个降解片段，为研究与肺病相关的SP-A降解产物的可能降解途径提供了初步的信息。证实了FT-ICR MS的高分辨率和高质量精确度在蛋白质的鉴定过程中的突出作用：（i）利用单个多肤的精确质量，可以避免依赖离子的串联质谱数据进行蛋白质鉴定，即无需对谱图中的离子进行串联质谱分析，就可实现蛋白质或蛋白质混合物的快速、确切的鉴定；（ii）在数据库检索中应用很小的误差范围可以大大提高蛋白质鉴定时的选择性；（iii）通过来自于微量蛋白质的少量肤峰就可以进行蛋白质的准确鉴定。通过MALDI/EST FT-ICR MS、园二色谱（CD）和H／D交换实验（hydrogedeuteriuln exchange）对一系列人SP-C及其类似物进行了表征。证实了溶液相中FFI-SP-C和rh-SP-C的非共价二聚体的存在；研究了人SP-C在有机溶剂中的构象变化和聚集行为，为探讨肺病相关机理奠定了基础。其次，以电喷雾多级串联质谱为研究手段，对部分生物类黄酮及其络合物进行系统的质谱研究，发现二氢黄酮及二氢黄酮醇类化合物在电喷雾条件负离子模式下具有不同的特征质谱行为，为质谱区分这两类化合物提供了重要的依据；黄酮金属络合物的研究中，四种二价过渡金属（Cu（II），Zn，Mn（II）和Fe（II））与芸香普均可以形成络合物，探讨了芸香普一铜络合物软电离条件下的碎裂机理，并利用多级串联质谱数据探讨了络合物C和D的结构，为质谱方法探讨金属清除疾病相关自由基的机理以及提高金属的生物利用度奠定了基础。

Low-temperature heat capacity and thermodynamic properties of crystalline 2-chloro-5-trichloromethylpyridine

The low-temperature heat capacities of 2-chloro-5-trichloromethylpyridine were measured with a high-precision automated adiabatic calorimeter in the temperature range from 80 K to 345 K. A solid-liquid phase transition was observed from 318.57 K to 327.44 K with peak temperature 324.67 K; the molar enthalpy and entropy of phase transition, DeltaH(m) and DeltaS(m), were determined to be 14.50 +/-0.02 kJ mol(-1) and 44.66 +/- 0.07 kJ K-1 mol(-1), respectively. The thermal stability was investigated through thermogravimetric analysis (TG). The TG and DTG results reveal that 2-chloro-5-trichloromethylpyridine starts to lose mass at 332 K due to evaporation and completely changes into vapour at 483 K under the present experimental conditions.

One-Step Synthesis and Luminescent Properties of Nanocrystalline YVO4:Eu3+ powders

In this paper, nanocrystalline YVO4:Eu3+ powders have been successfully synthesized via high-temperature solution-phase synthesis process. The nanocrystalline YVO4:Eu3+ particles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UVNis absorption spectra and luminescence spectra, luminescence decay curve and Fourier transform infrared (FT-IR), X-ray photoelectron spectra (XPS) respectively. The as-prepared nanocrystalline YVO4:Eu3+ particles are well crystallized with ellipsoidal morphology.

"Sandglass"-shaped self-assembly of coil-rod-coil triblock copolymer containing rigid aniline-pentamer

The amphiphilic PEG1 500-b-EM AP-b-PEG1 500 (EM PAP) triblock copolymer of poly(ethylene glycol) (PEG) and emeraldine aniline-pentamer (EM AP) in its concentrated solution can self-assemble into a special shape like "sandglass", as observed by transmission electron microscopy (TEM), field emission scanning electron microscopy (ESEM) and atomic force microscopy (AFM). This "sandglass"- shaped assembly is composed of several "rods" aggregated in the middle, with every "rod" being about 8 VLrn in length and 300 nm in diameter.

Self-assembly of single-stranded RNA on carbon nanotube: Polyadenylic acid to form a duplex structure

All messenger-RNA (mRNA) molecules in eukaryotic cells have a polyadenylic acid [poly (rA)] tail at the 3'-end and human poly (rA) polymerase (PAP) has been considered as a tumor-specific target. A ligand that is capable of recognizing and binding to the poly(M) tail of mRNA might interfere with the full processing of mRNA by PAP and can be a potential therapeutic agent. We report here for the first time that single-walled carbon nanotubes (SWNTs) can cause single-stranded poly (M) to self-structure and form a duplex structure, which is studied by UV melting, atomic force microscopy, circular dichroism spectroscopy, and NMR spectrometry.

Multicolor Tuning of Manganese-Doped ZnS Colloidal Nanocrystals

In this paper, we report a facile route which is based Oil tuning doping concentration of Mn2+ ions in ZnS nanocrystals, to achieve deliberate color modulation from blue to orange-yellow under single-wavelength excitation. X-ray diffraction (XRD), transmission electron microscopy (TEM), as well as photoluminescence (PL) spectra were employed to characterize the obtained samples. In this process, the relative emission intensities of both ZnS host (blue) and Mn2+ dopant (orange-yellow) are sensitive to the Mn2+ doping concentration, due to the energy transfer from ZnS host to Mn2+ dopant. As a result of fine-tuning of these two emission components, white emission can be realized for Mn2+-doped ZnS nanocrystals. Furthermore.

In situ preparation and luminescent properties of LaPO4:Ce3+, Tb3+ nanoparticles and transparent LaPO4:Ce3+, Tb3+/PMMA nanocomposite

LaPO4:Ce3+, Tb3+ nanoparticles were prepared by the reverse microemulsion with functional monomer, methyl methacrylate (MMA) as oil phase, and LaPO4:Ce3+, Tb3+/poly(methyl methacrylate) (PMMA) nanocomposite was obtained via polymerization of MMA monomer. The nanoparticles and nanocomposite have been well characterized by XRD, SEM, TEM, UV/vis spectrum, photoluminescence excitation and emission spectra and luminescence decays. The obtained solid nanocomposite LaPO4:Ce3+, Tb3+/PMMA is highly transparent and exhibits strong green photoluminescence upon UV excitation, due to the integration of luminescent LaPO4:Ce3+, Tb3+ nanoparticles. The luminescent lifetime of Tb3+ is determined to be 1.25 ms in the nanocomposite. (C) 2009 Elsevier Inc. All rights reserved.

Synthesis of a novel electroactive ABA triblock copolymer and its spontaneous self-assembly in water

An electroactive triblock copolymer of poly(ethylene glycol) (PEG) and aniline pentamer (AP), PEG-block-AP-block-PEG (PAP), was synthesized via polycondensation in the presence of N,N'-dicyclohexylcarbodiimide (DCC). The UV-vis spectra and cyclic-voltammograms (CV) spectra exhibited an excellent electroactivity of the triblock copolymer. The amphiphilic triblock copolymer self-assembles spontaneously into uniform micellar aggregates when the triblock copolymer was added directly to the aqueous solution. The size of the aggregates can be changed with the oxidation state of the AP segment in the PAP copolymer and the aggregates were pH-sensitive to the surrounding water solution, which provides a potential application in controlled drug release.

Synthesis and characterization of electroactive and biodegradable ABA block copolymer of polylactide and aniline pentamer

A triblock copolymer PLA-b-AP-b-PLA (PAP) of polylactide (PLA) and aniline pentamer (AP) with the unique properties of being both electroactive and biodegradable is synthesized by coupling an electroactive carboxyl-capped AP with two biodegradable bihydroxyl-capped PLAs via a condensation reaction. Three different molecule weight PAP copolymers are prepared. The PAP copolymers exhibit excellent electroactivity similar to the AP and polyaniline, which may stimulate cell proliferation and differentiation. The electrical conductivity of the PAP2 copolymer film (similar to 5 x 10(-6) S/cm) is in the semiconducting region. Transmission electron microscopic results suggest that there is microphase separation of the two block segments in the copolymer, which might contribute to the observed conductivity. The biodegradation and biocompatibility experiments in vitro prove the copolymer is biodegradable and biocompatible. Moreover, these new block copolymer shows good solubility in common organic solvents, leading to the system with excellent processibility. These biodegradable PAP copolymers with electroactive function thus possess the properties that would be potentially used as scaffold materials for neuronal or cardiovascular tissue engineering.

Identification, Characterization, and Molecular Application of a Virulence-Associated Autotransporter from a Pathogenic Pseudomonas fluorescens Strain

A gene, pfa1, encoding an autotransporter was cloned from a pathogenic Pseudomonas fluorescens strain, TSS, isolated from diseased fish. The expression of pfa1 is enhanced during infection and is regulated by growth phase and growth conditions. Mutation of pfa1 significantly attenuates the overall bacterial virulence of TSS and impairs the abilities of TSS in biofilm production, interaction with host cells, modulation of host immune responses, and dissemination in host blood. The putative protein encoded by pfa1 is 1,242 amino acids in length and characterized by the presence of three functional domains that are typical for autotransporters. The passenger domain of PfaI contains a putative serine protease (Pap) that exhibits apparent proteolytic activity when expressed in and purified from Escherichia coli as a recombinant protein. Consistent with the important role played by PfaI in bacterial virulence, purified recombinant Pap has a profound cytotoxic effect on cultured fish cells. Enzymatic analysis showed that recombinant Pap is relatively heat stable and has an optimal temperature and pH of 50 degrees C and pH 8.0. The domains of PfaI that are essential to autotransporting activity were localized, and on the basis of this, a PfaI-based autodisplay system (named AT1) was engineered to facilitate the insertion and transport of heterologous proteins. When expressed in E. coli, AT1 was able to deliver an integrated Edwardsiella tarda immunogen (Et18) onto the surface of bacterial cells. Compared to purified recombinant Et18, Et18 displayed by E. coli via AT1 induced significantly enhanced immunoprotection.