Research on the ultrafast fluorescence property of thylakoid membranes of the wild-type and mutant rice

A high yielding rice variety mutant (Oryza sativa L., Zhenhui 249) with low chlorophyll b (Chl b) has been discovered in natural fields. It has a quality character controlled by a pair of recessive genes (nuclear gene). The partial loss of Chl b in content affects the efficiency of light harvest in a light harvest complex (LHC), thus producing the difference of the exciting energy transfer and the efficiency of photochemistry conversion between the mutant and wild-type rice in photosynthetic unit. The efficiency of utilizing light energy is higher in the mutant than that in the wildtype rice relatively. For further discussion of the above-mentioned difference and learning about the mechanism of the increase in the photochemical efficiency of the mutant, the pico-second resolution fluorescence spectrum measurement with delay-frame-scanning single photon counting technique is adopted. Thylakoid membranes of the mutant and the wild-type rice are excited by an Ar+ laser with a pulse width of 120 ps, repetition rate of 4 MHz and wavelength of 514 nm. Compared with the time and spectrum property of exciting fluorescence, conclusions of those ultrafast dynamic experiments are: 1) The speeds of the exciting energy transferred in photo-system I are faster than that in photo-system II in both samples. 2) The speeds of the exciting energy transfer of mutant sample are faster than those of the wildtype. This might be one of the major reasons why the efficiency of photosynthesis is higher in mutant than that in the wild-type rice.

Experimental study on polarization holographic storage in genetic mutant BR-D96N film

Recording with both parallel and orthogonal linearly polarized lights, polarization holographic storage in genetic mutant BR-D96N film is reported with both transmission type geometry and reflection type geometry. Polarization properties of diffraction light and scattering light are discussed for two different cases, parallel polarization recording and orthogonal polarization recording. It shows that, compared with recording with parallel polarization lights, orthogonal polarization holography can separate the diffraction light from the scattering noise, therefore improving the signal-to-noise ratio. It also shows that, compared with reconstruction with reference light, reconstruction with phase conjugated wave of the reference light can improve the signal-to-noise ratio of the reconstructed diffraction image, and also the wave-front aberration of the object light introduced by irregular phase object in the optical pass-way can also be corrected effectively, which ensures that the reconstructed diffraction image has a better fidelity. The preliminary angle-multiplexed volume holographic storage multiplexed by transmission type geometry and reflection type geometry is demonstrated in the BR-D96N film. Experiment shows that there is no cross-talk between the two pages of images except for some scattering noises.

Nonapeptide突变体制备及抗新城疫病毒活性研究；Preparation of Nonapeptide Mutant and Antiviral Effect on Newcastle Disease Virus

以生物工程技术表达及120 g/L SDS-PAGE电泳纯化Nonapeptide突变体,取制备的Non-apeptide突变体进行抗新城疫病毒(NDV)的鸡胚试验、鸡体内抗NDV试验。结果表明,当Nonapeptide突变体基因产物浓度达4μg/mL～6μg/mL,对鸡胚保护率均达到100%,感染鸡胚全部存活;Nonapeptide突变体基因产物浓度大于4μg/mL,对NDV有很好的抑制作用,鸡用药后3 d体内检测不到NDV,低剂量组(2μg/mL)也有较好的抑制NDV作用,鸡用药后5 d体内检测不到NDV。Nonapeptide突变体基因产物具有NDV多克隆抗体相似活性,能够抑制鸡胚中和组织培养中NDV的繁殖,具有中和、抑制NDV吸附作用。

~(12)C离子束辐照对酵母发酵能力的影响；Improved ethanol fermentation of a yeast mutant by C-12 ion beam irradiation

利用100MeV/u的12C6+离子束辐照酵母Saccharomyces cerevsiea YY,选育出一株高产突变菌株C03A,考察C03A发酵过程中不同温度、pH、糖汁浓度对发酵的影响。通过正交实验确定最佳发酵条件为:糖汁浓度24%、温度35℃、pH5.0。在10L发酵罐实验中,C03A发酵速率相对原始菌株高,36h发酵完全,比原始菌株缩短12h;发酵产酒率达到13.2%(V/V),比原始菌株高1.6%(V/V)。

Surface-enhanced resonance Raman spectroscopic study of yeast iso-1-cytochrome c and its mutant

The structural stability and redox properties of yeast iso-1-cytochrome c and its mutant, F82H, were studied by surface-enhanced resonance Raman scattering (SERRS) spectroscopy. Phenylalanine, which exists at the position-82 in yeast iso-1-cytochrome c, is replaced by histidine in the mutant. The SERRS spectra of the proteins on the bare silver electrodes indicate that the mutant possesses a more stable global structure with regard to the adsorption-induced conformational alteration. The redox potential of the mutant negatively shifts by about 400 mV, relative to that of yeast iso-1-cytochrome c. This is ascribed to axial ligand switching and higher solvent accessibility of the heme iron in the mutant during the redox reactions.

Circular dichroism and resonance Raman comparative studies of wild type cytochrome c and F82H mutant

The UV-visible, circular dichroism (CD), and resonance Raman (RR) spectra of the wild type yeast iso-1-cytochrome c (WT) and its mutant F82H in which phenylalanine-82 (Phe-82) is substituted with His are measured and compared for oxidized and reduced forms. The CD spectra in the intrinsic and Soret spectral region, as well as RR spectra in high, middle, and low frequency regions, are discussed. From the analysis of the spectra, it is determined that in the oxidized F82H the two axial ligands to the heme iron are His-18 and His-82 whereas in the reduced form the sixth ligand switches from His-82 to Met-80 providing the coordination geometry similar to that of WT. Based on the spectroscopic data, the conclusion is that the porphyrin macrocycle is less distorted in the oxidized F82H compared to the oxidized WT. Similar distortions are present in the reduced form of the proteins. Frequency shifts of Raman bands, as well as the decrease of the or-helix content in the CD spectra, indicate more open conformation of the protein around the heme. (C) 2000 John Wiley & Sons, Inc.

Induction and characterization of green pigmentation mutant in Porphyra yezoensis Ueda

The free living conchocelis of Porphyra yezoensis Ueda was treated with N-methyl-N-nitro-N-nitrosoguanidine to induce pigmentation mutants. The artificial green pigmentation mutant of P. yezoensis conchocelis, which was composed entirely of green cells, was isolated through visualization with the unaided eye. The acquired green conchocelis was further developed into a green gametophytic blade. This mutant was relatively stable in color in both gametophytic blade and conchocelis phases. The gametophytic blade mutant was successively cultivated for commerce at some Porphyra farms in Rudong, China, and few wild type or sectorially variegated gametophytic blade occurred, indicating that the green mutant has commercial value. The green mutant was characterized as having lower phycoerythrin and higher phycocyanin content, and SDS-PAGE suggested that phycoerythrin was missing the gamma-subunit in comparison to the wild type. The wild type and the green mutant showed a clear difference in 02 evolution rates in white, green, yellow, and red light, which might be due to the qualitative and quantitative changes of phycoerythrin, and the quantitative difference of phycocyanin. (C) 2008 Elsevier B.V. All rights reserved.

Construction and characterization of a live, attenuated esrB mutant of Edwardsiella tarda and its potential as a vaccine against the haemorrhagic septicaemia in turbot, Scophthamus maximus (L.)

The esrB gene of Edwardsiella tarda, which encodes a regulator protein of the type III secretion system, was mutated by the unmarked deletion method and reintroduced by allelic exchange into the chromosome of E. tarda LSE40 by means of the suicide vector pRE 112. The LSE40 esrB mutant was highly attenuated when inoculated intraperitoneally into turbot Scophthamus maximus L., showing a 50% lethal dose of 10(8.1) cfu/fish. The esrB mutants were not recoverable from the internal organs at 14 days post-inoculation. Vaccination with a single dose of 10(5)-10(7) cfu/fish of the esrB mutant elicited significant protection against the wildtype strain of E. tarda LSE40 (relative percentage survival > 50%). The protection correlated well with the antibody titres in the serum of vaccinated fish. (c) 2006 Elsevier Ltd. All rights reserved.

Comparative analysis of astaxanthin and its esters in the mutant E1 of Haematococcus pluvialis and other green algae by HPLC with a C30 column

A gradient reversed-phase high-performance liquid chromatography (HPLC) method using a C30 column was developed for the simultaneous determination of astaxanthin, astaxanthin monoesters and astaxanthin diesters in the green algae Chlorococcum sp., Chlorella zofingiensis, Haematococcus pluvialis and the mutant E1, which was obtained from the mutagenesis of H. pluvialis by exposure to UV-irradiation and ethyl methanesulphonate (EMS) with subsequent screening using nicotine. The results showed that the contents of total astaxanthins including free astaxanthin and astaxanthin esters ranged from 1.4 to 30.9 mg/g dry biomass in these green algae. The lower total astaxanthin levels (< 2 mg/g dry biomass) were detected in the green algae Chlorococcum sp. and C. zofingiensis. The higher total astaxanthin levels (> 16 mg/g dry biomass) were found in the green alga H. pluvialis and its mutant E1. It is notable that the mutant E1 is found to have considerably higher amounts of total astaxanthin (30.9 mg/g) as compared to the wild strain of H. pluvialis (16.1 mg/g). This indicates that UV-irradiation and EMS compound mutagenesis with subsequent screening using nicotine is an effective method for breeding of a high-producing astaxanthin strain of H. pluvialis. In addition, the green alga C. zofingiensis had a remarkably higher percentage of astaxanthin diesters (76.3% of total astaxanthins) and a remarkably lower percentage of astaxanthin monoesters (18.0% of total astaxanthins) in comparison with H. pluvialis (35.5% for diesters and 60.9% for monoesters), the mutant E1 (49.1% and 48.1%) and Chlorococcum sp. (18.0% and 58.6%).

Light energy conversion into H-2 by Anabaena variabilis mutant PK84 dense cultures exposed to nitrogen limitations

Concentrated cultures (25-86 mg Chl a l(-1)) of Anabaena variabilis PK84 were incubated under 99% Ar+1% CO2 atmosphere in the photobioreactor made of coaxial cylinders. Under illumination equal to 353 mu E m(-2) s(-1) they produced hydrogen with the rate more than 20 ml l(-1) h(-1) for several days. The efficiency of light energy conversion into H-2 was approx. 1% and did not depend significantly on initial Chl a concentration. H-2/O-2 ratio reached 41.5% of theoretical value for water photolysis. Data indicate that dense cultures might be used for outdoor systems under direct sun light. Supra-optimal temperatures 36 degrees C were not harmful for cultures even for 2 days period. Short-term incubation of cultures under 36 degrees C even increased H2 production rate and efficiency of light energy bioconversion by 1.25 times. (c) 2006 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.

固氮酶金属原子簇对其结构和功能的影响

一、 △nifZ MoFe蛋白的纯化、特性及晶体生长 从缺失nifZ的棕色因氮菌突变种DJ194中，经离子交换层析和凝胶过滤提纯得到△nifZ MoFe蛋白，其纯度可达SDS凝胶电泳纯。它的Fe、Mo含量分别为野生型OP MoFe蛋白的56.6%和75.0%左右;C_2H_2、H~+还原活性和△H_2均只有OP MoFe蛋白的14.6%、21.7%和21.7%;其可见吸收光谱、CD及AR谱都与OP MoFe蛋白有较大差异，其中，可以反应P-cluster氧还状态和含量的ε_(450nm)、ε_(700nm)及△ε_(450nm)均要比OP MoFe蛋白低;由紫外CD谱反映的△nifZ MoFe蛋白的构象也与OP MoFe蛋白有所不同。由此我们推测，nifZ可能与固氮酶MoFe蛋白中P-cluster的合成或组装有关。为进一步阐明△nifZ MoFe蛋白的结构和功能特性，我们对△nifZ MoFe蛋白的晶体生长进行了研究，通过对沉淀剂浓度、缓冲体系和pH、蛋白浓度以及温度等条件的不断优化组合，目前我们已获得棕色短斜四棱柱形△nifZ MoFe蛋白的最大晶体为0.15 * 0.09mm。 二、 MoFe(C,O)与含Mo、Mn和Cr重组液重组的比较研究 MoFe(R)经O_2和o-phen共同处理后，成为部分缺失FeMoco和P-cluster的不全蛋白(MoFe(C,O))，其C_2H_2还原活性降至MoFe(R)的40%左右，将其分别与含Mo、Cr和Mn的重组液进行保温重组，其C_2H_2还原活性及光谱学特征都得到明显恢复。通过对不同重组液及与MoFe(C,O)形成的重组蛋白的比较，我们认为：1)MoFe(R)中的Fe和Mo原子可能是逐步被鳌合除去的，且不同蛋白中的Fe和Mo原子的缺失程度不同，因而MoFe(C,O)会以多种状态存在;2)在重组液配制过程中，发生的一系列颜色变化及沉淀反应与其是否具有重组激活能力具有相关性，重组液中可能已合成一些简单的含M(M=Mo或Cr或Mn或V)的铁硫化物，但不可能形成完整的金属原子簇;3)含M(M=Mo或Cr或Mn)的重组液均能使MoFe(C,O)中遭到破坏的FeMoco和P-cluster及其连接部分得以重新组装和修复，进而恢复其底物还原活性和光谱学特征。 三、 含锰固氮酶的初步探索 棕色固氮菌突变种UW_3(nifH~-)不能在含钼的培养中固氮生长，但能在含MnSO_4的无氮培养基中固氮生长。用含MnSO_4的无钼无氮培养基培养该突变种从中纯化得到的固氮酶组分1蛋白，其C_2H_2及H~+还原活性约相当于MoFe(R)的20%左右，Mn元素含量测定表明，其中已经含有Mn元素，Fe/Mn比值比OP MoFe蛋白中的Fe/Mo低。这些结果表明：UW_3突变种在该种条件下可能已表达了不同于已发现的三种固氮酶的新的固氮酶组分1蛋白，并且其中含有Mn元素。