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971.
The model conjugates phycocyanin-allophycocyanin (C-PC-APC) and phycoerythrocyanin-phycocyanin-allophycocyanin (PEC-C-PC-APC)
were synthesized by using a heterobifunctional coupling reagent N-succinimidyl-3-(2-pyridyldithio)propionate. The rod-core
complex (αβ)6
PCLRC
27(αβ)3
APCLC
8.9 and phycobilisomes were separated from Anabaena variabilis. Energy transfer features for the conjugates and the complexes
were compared. The absorption and fluorescence emission spectra indicated that the linker-peptides mediate interaction of
phycobiliproteins and prompt energy transfer. The energy transfer in the conjugates was detected by fluorescence emission
spectra and confirmed by the addition of dithiothreitol. The conjugates may be used as models for studying the energy transfer
mechanism in phycobilisomes.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
972.
973.
Silicon-mediated alleviation of Mn toxicity in Cucumis sativus in relation to activities of superoxide dismutase and ascorbate peroxidase 总被引:14,自引:0,他引:14
The effects of exogenous silicon (Si) on plant growth, activities of superoxide dismutase (SOD), guaiacol peroxidase (GPX), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), glutathione reductase (GR) and catalase, and concentrations of ascorbate and glutathione were investigated in cucumber (Cucumis sativus L.) plants treated with excess manganese (Mn) (600 microM). Compared with the treatment of normal Mn (10 microM), excess Mn significantly increased H2O2 concentration and lipid peroxidation indicated by accumulation of thiobarbituric acid reactive substances. The leaves showed apparent symptoms of Mn toxicity and the plant growth was significantly inhibited by excess Mn. The addition of Si significantly decreased lipid peroxidation caused by excess Mn, inhibited the appearance of Mn toxicity symptoms, and improved plant growth. This alleviation of Mn toxicity by Si was related to a significant increase in the activities of SOD, APX, DHAR and GR and the concentrations of ascorbate and glutathione. 相似文献
974.
Two novel ion-pair complexes, [RBzIQl]+[Ni(mnt)2]− (mnt2− = maleonitriledithiolate, [RBzIQl]+ = 4-R-benzylisoquinolinium; R = H (1), Cl (2)) have been characterized structurally and magnetically. The anions and [BzIQl]+ cations of 1 form 1D column of alternating between cations and anions via π?π stacking interaction between Ni(mnt)2 plane and isoquinoline ring, and the Ni(mnt)2 anions between adjacent columns exist C?N, C?N, and N?N interaction. The anions and cations of 2 stack into well-segregated columns in the solid state; and the Ni(III) ions form a 1D zigzag chain in a Ni(mnt)2 column through intermolecular Ni?S, S?S, Ni?Ni or π?π interactions. The chain is uniform in 2 with the Ni?Ni distances of 3.784 Å. Magnetic susceptibility measurements for these complexes in the temperature range 1.8-300 K show that 1 exhibits antiferromagnetic coupling behavior, and 2 exhibits unusual magnetic phase transitions around 45 K. The overall magnetic behavior for 2 indicates the presence of antiferromagnetic interaction in the high-temperature phase (HT) and spin gap in the low-temperature phase (LT). 相似文献
975.
Three group 10 complexes containing nido-carborane diphosphine, [NiCl(PPh3){7,8-(PPh2)2-7,8-C2B9H10}] (1), [PdCl(PPh3){7,8-(PPh2)2-7,8-C2B9H10}] · 1.25CH2Cl2 (2) and [PtCl(PPh3){7,8-(PPh2)2-7,8-C2B9H10}] · 2.5CH2Cl2 (3) have been synthesized by the reactions of [M(PPh3)2Cl2] (M = Ni, Pd, Pt) with closo carborane diphosphine 1,2-(PPh2)2-1,2-C2B10H10 in ethanol. For complex 3, it could also be obtained under solvothermal condition. All three complexes were characterized by elemental analysis, FT-IR, 1H and 13C NMR spectroscopy and X-ray structure determination. Single crystal structures show that their structures are similar to each other. In each complex, the nido [7,8-(PPh2)2-7,8-C2B9H10]−, which resulted from the degradation of the initial closo ligand 1,2-(PPh2)2-1,2-C2B10H10 during the reaction process, was coordinated bidentately through the P atoms to M(II) ion, and this resulted in a stable five-membered chelating ring between the bis-diphosphine ligand and the metal. The coordination mode of the metal can be described as a slightly distorted square-planar, in which the remaining two positions were occupied by one Cl− and one PPh3 group. 相似文献
976.
977.
Paul W. Weber Laurens E. Howle Mark M. Murray Joseph M. Corless 《Biophysical journal》2011,100(3):525
When radiolabeled precursors and autoradiography are used to investigate turnover of protein components in photoreceptive cone outer segments (COSs), the labeled components—primarily visual pigment molecules (opsins)—are diffusely distributed along the COS. To further assess this COS labeling pattern, we derive a simplified mass-transfer model for quantifying the contributions of advective and diffusive mechanisms to the distribution of opsins within COSs of the frog retina. Two opsin-containing regions of the COS are evaluated: the core axial array of disks and the plasmalemma. Numerical solutions of the mass-transfer model indicate three distinct stages of system evolution. In the first stage, plasmalemma diffusion is dominant. In the second stage, the plasmalemma density reaches a metastable state and transfer between the plasmalemma and disk region occurs, which is followed by an increase in density that is qualitatively similar for both regions. The final stage consists of both regions slowly evolving to the steady-state solution. Our results indicate that autoradiographic and cognate approaches for tracking labeled opsins in the COS cannot be effective methodologies for assessing new disk formation at the base of the COS. 相似文献
978.
截线抽样法广泛应用于鲸豚类动物的考察。通过文献调查并结合我们自己的研究工作,本文从考察设计、
野外考察和数据分析三个方面分析了截线抽样法在我国水域应用时可能出现的问题。针对考察设计,提出了截
线设计的建议。针对野外考察,主要从观察平台、人员配置、观察方法和记录方法几个方面提出建议。针对分
析过程,介绍了使用R 编程平台和Distance 软件进行数据预处理和数据分析的简要过程。笔者期望本文的相关
建议有助于促进我国鲸豚类考察方法的规范化。 相似文献
野外考察和数据分析三个方面分析了截线抽样法在我国水域应用时可能出现的问题。针对考察设计,提出了截
线设计的建议。针对野外考察,主要从观察平台、人员配置、观察方法和记录方法几个方面提出建议。针对分
析过程,介绍了使用R 编程平台和Distance 软件进行数据预处理和数据分析的简要过程。笔者期望本文的相关
建议有助于促进我国鲸豚类考察方法的规范化。 相似文献
979.
Li C Wang X Wang G Wu C Li N 《Comparative biochemistry and physiology. Part D, Genomics & proteomics》2011,6(3):264-270
Roxarsone is a commonly used additive in chicken (Gallus gallus) industry. However, little is known on the intrinsic molecular mechanism via which the growth performance of birds improves. This study was therefore performed to investigate the expression profiles of genes induced by roxarsone. Fifty-six broiler chickens were divided into two groups, namely treated and untreated with roxarsone. The treated group was provided a diet of 45.4 mg/kg roxarsone medication and the other group acted as control. Data analysis showed that roxarsone consistently and significantly (P < 0.05) increased chicken growth performance. In addition to this a significant (P < 0.05) increase of arsenic residue in liver has been seen. Microarray expression analysis of 8935 genes in liver showed that 22 genes (10 up- and 12 down-regulated) had altered expression throughout the experimental periods. Two novel genes (GenBank accession no. GU724343 and GU724344) were cloned through rapid amplification of cDNA ends (RACE). Gene GU724343 was predicted to encode an unidentified protein and the second gene GU724344 was presumed to encode a new member of immunoglobulin-like receptor (CHIR) family. Our results suggested for the first time that the role of roxarsone could be mainly to modify the expression levels of cell growth, immunity/defense and energy metabolism associated genes, as a result promoting animal growth. Further research on these genes should help to increase the knowledge of improving animal productivity safely and effectively. 相似文献
980.
Three phase partitioning (TPP) is most renowned technique used for extraction and purification of natural products. In previous studies of TPP, t-butanol is mainly used as an organic phase. This is the first report that explores ability of dimethyl carbonate (DMC) in the field of TPP as an alternate solvent for t-butanol. In the present study TPP process with t-butanol and DMC as organic phase along with different salts was applied to waste bitter gourd powder to obtained peroxidase enzyme. DMC was found to be compatible with most of salts such as ammonium sulphate and sodium citrate and explored as more efficient solvent than t-butanol. This TPP system provides 4.84 fold purity of peroxidase enzyme at optimum source concentration of 0.15 g/mL, with a system comprising DMC as organic phase, sodium citrate (20%) as salt, agitation speed 120 rpm, pH 7, temperature 30 °C and extraction time of 3 h. Present study has aimed for extraction and separation of peroxidase from bitter gourd waste with TPP technique and ensures the scope of carbonated solvents in extraction and purification of proteins. 相似文献