Surface renewable graphite organosilicate composite electrode containing indium(III) hexacyanoferrate(II/III)

Indium(III) hexacyanoferrate(II/III) (InHCF) supported on graphite powder was prepared using the in situ chemical deposition procedure and subsequently dispersed into methyltrimethoxysilane-derived gels to yield a conductive graphite organosilicate composite. The composite was used as the electrode material to fabricate a three-dimensional InHCF-modified electrode. InHCF acts as a catalyst, graphite powder ensures conductivity by percolation, the silicate provides a rigid porous backbone and the methyl groups endow hydrophobicity and thus limit the wetting section of the modified electrode. The chemically modified electrode can electrocatalyze the oxidation of thiosulfate, and exhibits a good repeatability of surface-renewal by simple mechanical polishing, as well as simple preparation, good chemical and mechanical stability.

Chemical bond properties of rare earth ions in crystals

By using the dielectric description theory of ionicity of solids, chemical bond properties of rare earth ions with various ligands are studied. Calculated results show that chemical bond properties of the same rare earth ion and the same ligand in different crystals depend on the crystal structures. In a series of compounds, chemical bond properties of crystals containing different rare earth ions are similar. The magnitude of covalency of chemical bonds of trivalent rare earth ions and various ligands has an order like F

High efficient extraction of M@C-2n (M = La, Ce) by a high pressure and high temperature method

A high pressure and high temperature method was used to efficiently extract on a large scale metallofullerenes M@C-2n (M=La,Ce) in a closed vessel under argon gas protection. With pyridine as the HPHT solvent, about 60-80% M@C-2n and 30-55% M@C-82 can be enriched, M@C-82 is dissolved selectively; With toluene as the HPHT solvent, M@C-2n can also be efficiently extracted, especially M@C-74, which is a new member of M@C-2n soluble species. (C) 1998 Elsevier Science Ltd. All rights reserved.

High temperature and high pressure extraction of lanthanofullerenes by using different solvents

The traditional Soxhlet extraction of lanthanofullerenes was improved and the high temperature and high pressure method with different extraction solvents was used. It's found that La@C-2n can be efficiently extracted with toluene and pyridine from the insoluble part of the soot after the toluene Soxhlet extraction. Pyridine can more efficiently and selectively extract lanthofullerenes, especially La@C-82, while toluene can extract La@C-74, which is a new member added to the soluble species to lanthanofullerenes.

Crystal field splitting of Nd3+ ion and chemical bonds on the host crystals

In terms of the theory of chemical bonds on complex crystals(CBCC), the crystal structure and coordination, the chemical bond parameters of a group of ABO(4)-type crystals were calculated in detail, The results show that the relation between the crystal field splitting of Nd3+ ion and the covalency of the crystal is linear.

Effect of structures of modifiers on electrochemistry of di-mu-oxo dimanganese 2,2'-bipyridine complex

The gold electrodes modified with 2-picolinic acid , nicotinic acid, iso-nicotinic or thiophene were prepared using membrane transfer method, The electrochemistry of di-mu-oxodimanganese 2,2'-bipyridine complex was studied in the acetic acid buffer solution at different modified gold electrodes, It was found that the modifiers which can promote the electrochemical reaction of the complex should be of at least two functional groups, One group can be bound to the electrode surface and the other can form electron transfer pathway between the modifier and the complex through sal; bridge or hydrogen bond, In addition, the mechanism of the electrochemical reaction was discussed.

A STUDY ON CH5O+ IONS IN GAS PHASE CID EYPERIMENT AND QUANTUM CHEMISTRY CALCULATION

The structures of CH5O+ from two different reactions which are protonation of CH3OH from the above two pathways possess the same structures, CH3OH2+. The value of kinetic energy release for the metastable decomposition CH2OH3+-> CH2OH+ + H-2 determined from the experiment is in good agreement with that from theoretical calculations. The transition state of above reaction were disscussed.

Cloning and characterization of beta-carotene ketolase gene promoter in Haematococcus pluvialis

The unicellular green alga Haematococcus pluvialis accumulates a highly valuable ketocarotenoid, astaxanthin, under various environmental stresses. beta-carotene ketolase (BKT) plays a key role in astaxanthin biosynthesis in H. pluvialis. In this paper, an approximate 700 bp 5'-flanking region of the bkt gene containing a putative promoter was cloned through walking upstream. The results of the sequence analysis showed that this bkt 5'-flanking region might have cis-acting elements such as sterol regulatory element (SRE-1)-like motifs, the C-repeat/dehydration responsive element (DRE) and al-3 proximal element (APE)-like motifs, except for typical TATA and CCAAT boxes. The results of the P-galactosidase assay and the transient expression of lacZ driven by a series of sequential deletions revealed that a minimal promoter-like region might exist from -630 to -408 bp, and the highest promoter activity was observed to span the positions from -630 to -308 bp. The results of the site-directed mutagenesis of a C-repeat/DRE and two APE-like motifs in a promoter-like region (-630 to -308 bp) suggested that two APE-like motifs might be essential for transcriptional control of the bkt gene.

Recombination and heterologous expression of allophycocyanin gene in the chloroplast of Chlamydomonas reinhardtii

Heterogeneous expression of multiple genes in the nucleus of transgenic plants requires the introduction of an individual gene and the subsequent backcross to reconstitute multi-subunit proteins or metabolic pathways. In order to accomplish the expression of multiple genes in a single transformation event, we inserted both large and small subunits of allophycocyanin gene (apcA and apcB) into Chlamydomonas reinhardtii chloroplast expression vector, resulting in papc-S. The constructed vector was then introduced into the chloroplast of C. reinhardtii by micro-particle bombardment. Polymerase chain reaction and Southern blot analysis revealed that the two genes had integrated into the chloroplast genome. Western blot and enzyme-linked immunosorbent assay showed that the two genes from the prokaryotic cyanobacteria could be correctly expressed in the chloroplasts of C. reinhardtii. The expressed foreign protein in transformants accounted for about 2%-3% of total soluble proteins. These findings pave the way to the reconstitution of multi-subunit proteins or metabolic pathways in transgenic C. reinhardtii chloroplasts in a single transformation event.

Molecular cloning, characterization and evolutionary analysis of phytoene desaturase (PDS) gene from Haematococcus pluvialis

Phytoene desaturase is one of the most important enzymes necessary for the biosynthesis of carotenoids in some cyanobacteria, green algae and plants. In this study, genomic DNA and cDNA of pds were cloned from unicellular green alga Haematococcus pluvialis strain323 using PCR and RT-PCR methods. The cDNA was cloned into plasmid pET-28a and efficiently expressed in Escherichia coli BL21. The complete genomic PDS gene of H. pluvialis, 3.3 kb in size, included eight exons and seven introns. To locate transcriptional regulation elements, an approximate 1 kb of 5'-flanking region was isolated by genome-walking method. Results of bioinformatic analysis showed several putative cis-elements e.g. the ABRE motif (abscisic acid responsive element), the C-repeat/DRE (dehydration responsive element) motif and the GCN4 motif were located in 5'-flanking region of pds. Results of phylogenetic analyses reveal that different sources of PDS genes form a separate clade, respectively, with 100% bootstrap support. Moreover, a maximum likelihood approach was employed to detect evidence of positive selection in the evolution of PDS genes. Results of branch-site model analysis suggest that 7.9% of sites along the green algal branch are under positive selection, and the PDS gene in green algae exhibits a different evolutionary pattern from its counterparts in cyanobacteria and plants.

There are two 5 '-flanking regions of bkt encoding beta-carotene ketolase in Haematococcus pluvialis

The unicellular green alga Haematococcus pluvialis accumulates a commercially valuable astaxanthin, with levels reaching up to 4% dry weight under environmental stress. In recent years, much effort has been devoted to understanding the molecular mechanisms regulating astaxanthin biosynthetic pathways. Beta-carotene ketolase (bkt), with control being exhibited at the transcription level, plays an important role in astaxanthin biosynthesis by H. pluvialis. Here we demonstrate the presence of two separate 5'-flanking regions [1.5 kilobase (kb) and 2 kb] of bkt (bkt1 and bkt2) that possess regulatory elements similar to those of known stress-responsive genes in plants. Results of 5'-deletion constructs and transient beta-galactosidase expression assays demonstrate that there may be positive regulatory elements governing expression in the shorter promoter at -1060/-900 from the 1.5 kb 5' region, and in the longer promoter at -1838/-1219 and at -1046/ -734 from the 2 kb 5' region relative to each homologous ATG start codon. Furthermore, our present studies reveal that the first intron (+371/+497) downstream from the 1.5 kb 5' untranslated region of bkt1 may function as a negative regulatory element to regulate its own promoter.

The recombination and expression of the allophycocyanin beta subunit gene in the chloroplast of Chlamydomonas reinhardtii

A Chlamydomonas reinhardtii (C. reinhardtii) chloroplast expression vector, papc-B, containing the apc-B gene that encodes the beta subunit of the light-harvesting antenna protein allophycocyanin (APC) of cyanobacteria, was constructed and transferred to the chloroplast genome of C. reinhardtii by the biolistic method. The transformants were identified by Southern blot, Western blot and ELISA assays after selection on resistant medium. The recombinant APC beta subunit was expressed in the C. reinhardtii chloroplast and accounted for up to 2-3% (w/w) of the total soluble protein (TSP), suggesting a promising prospect of using C. reinhardtii chloroplasts to produce functional plant-derived proteins.

大西洋庸鲽Hippoglossus hippoglossus和大西洋鲑Salmo salar配子质量研究

种质问题是养殖健康发展的基础。在鱼类养殖中，卵子和精子的质量直接关系到受精、胚胎发育，仔稚鱼发育以及幼鱼生长等一系列过程。本论文针对大西洋庸鲽和大西洋鲑的配子质量进行研究。研究内容涉及大西洋庸鲽精子冷冻保存方法；促性腺激素释放激素类似物（GnRHa）使用对其精子冷冻保存效果、以及脂肪酸组成的影响；野生和驯养大西洋鲑卵子在脂肪酸、类胡萝卜素、矿物盐方面的差异比较。 精子冷冻保存通过提高对精子的利用效率，进而对于种质改良，推进鱼类养殖科研和生产具有重要意义。本实验建立了大西洋庸鲽精子大容量冷冻保存方法。八种抗冻剂冷冻保存实验结果表明：10% 及15% DMSO配以 HBSS 或KS 的抗冻剂组合冷冻保存效果最佳，4 mL体积冷冻保存可获得与1.6 mL同样的保存效果。 在繁殖季节后期注射GnRHa激素缓释剂，可获得质量稳定的大西洋庸鲽精液，将激素注射方法与精子冷冻保存方法相结合对于提高雄鱼利用率，扩大生产规模具有重要实用价值。本项研究分三个时间采集注射GnRHa激素后的雄鱼精子以及同期未注射激素的雄鱼精子，对所有精子样品使用同样的方法进行冷冻保存，检测冷冻保存后解冻精子的受精率与活力。结果表明，激素注射与否对于冷冻保存后精子的受精率和活力无显著影响，两类冷冻精液均达到鲜精水平。实验结果还表明，注射激素14天后的精子的密度显著的降低。说明GnRHa激素的使用可以显著降低精子密度，但不会影响精子的冷冻保存效果。 本相研究同时对注射GnRHa 缓释激素和未注射GnRHa 缓释激素的大西洋庸鲽精液脂肪酸成分进行分析，以检测该激素使用对精子生化组分的影响。结果表明激素的使用对在DHA (22:6n-3,二十二碳六烯酸)、EPA(20:5n-3,二十碳五烯酸)、AA(20:4n-6，花生四烯酸)等重要脂肪酸，不饱和脂肪酸、饱和脂肪酸以及n-3、n-6等重要种类的脂肪酸总量及其比例没有显著影响。精液脂肪酸中DHA含量最高，约占25%；PUFA约为44%。 作为世界性的重要养殖品种，野生和驯养大西洋鲑在形态、生化组成以及遗传 等方面表现出的差异被广泛关注。本论文，对野生和驯养大西洋鲑受精卵关键生化成分进行分析，通过与野生受精卵比较阐明驯养受精卵的质量状况，为亲鱼营养需求提供指导依据。本实验中野生配子和驯养配子的受精率没有显著差异，但重要脂肪酸组成、类胡萝卜素以及矿物盐含量都存在多方面显著差异。两类受精卵脂肪酸中含量最高的依次为18:1n-9（油酸）、DHA（二十二碳六烯酸）、16:0（棕榈酸）、EPA（二十碳五烯酸）。野生受精卵的单不饱和脂肪酸总量显著高于驯养受精卵，而多不饱和脂肪酸（PUFA）比例显著低于驯养的受精卵。在主要必需不饱和脂肪酸（EFA）中，DHA和EPA在野生受精卵中的比例高于驯养受精卵，AA（花生四烯酸）低于驯养受精卵。野生受精卵虾青素（Ax）的含量低于驯养受精卵而鸡油菌素（Cx）含量高于驯养受精卵。野生受精卵中多种矿物盐的含量（铝、铜、铁、硒和锌）含量显著高于驯养的受精卵。差别最大的为铜。诸多方面的差异表明，野生亲鱼与驯养亲鱼产出的卵子确实存在显著差异，因此关注亲鱼的营养极为重要。

Prevention of fish oil rancidity by phlorotannins from Sargassum kjellmanianum

Known only in the Phaeophyceae, phlorotannins (brown algal polyphenols) are a class of natural products with potential uses in pharmacology. This study reports that phlorotannins from Sargassum kjellmanianum can prevent fish oil from rancidification; the antioxidation activity was about 2.6 times higher than that of 0.02% BHT (tertbutyl-4-hydroxytoluene).