Multiple Excitation Wavelength Fluorescence Emission Spectra Technique for Discrimination of Phytoplankton

In vivo fluorescence methods are efficient tools for studying the distribution of phytoplankton in nature.Different algae species usually have different pigments with different ratios,which results in different fluorescence emission spectra.Based on multiple excitation wavelength fluorescence emission spectra,a discrimination technique is established in this study.The discrimination method,established by multivariate linear regression and weighted least-squares,was used to differentiate the samples cultured in the laboratory and collected from Jiaozhou Bay near Qingdao at the division level.The correctly discriminated samples were ≥ 86% for single algae samples,≥ 88% for simulatively mixed ones,≥ 91% for physically mixed ones and 100% for samples collected from Jiaozhou Bay.The result in this research is more definite for the physically mixed samples in the laboratory.The method described here can be employed to monitor the phytoplankton population in the marine environment.

Photosynthetic Characteristics of Flag Leaves in Rice White Stripe Mutant 6001 During Senescence Process

Physiological, biochemical and electron microscopy analyses were used to investigate the photosynthetic performance of flag leaves in rice white stripe mutant 6001 during the senescence process. Results showed that the chlorophyll content at the heading and milk-ripe stages in rice mutant 6001 were about 34.78% and 3.00% less than those in wild type 6028, respectively. However, the chlorophyll content at the fully-ripe stage in rice mutant 6001 was higher than that in wild type 6028. At the heading stage, the net photosynthetic rate （Pn） in rice mutant 6001 was lower than that in wild type 6028. Rice mutant 6001 also exhibited a significantly slower decrease rate of Pn than wild type 6028 during the senescence progress, especially at the later stage. Furthermore, Ca2^-ATPase, Mg~^-ATPase and photophosphorylation activities exhibited the similar trends as the Po. During the senescence process, the 68 kDa polypeptide concentrations in the thylakoid membrane proteins exhibited a significant change, which was one of the critical factors that contributed to the observed change in photosynthesis. We also observed that the chloroplasts of rice mutant 6001 exhibited higher integrity than those of wild type 6028, and the chloroplast membrane of rice mutant 6001 disintegrated more slow during the senescence process. In general, rice mutant 6001 had a relatively slower senescence rate than wild type 6028, and exhibited anti-senescence properties.

Absorption and Fluorescence Emission Spectra of Molecules Containing Azo and/or Oxadiazole Units

The ground state structures of a series of organic molecules containing azo and/or oxadiazole units were obtained by means of density functional theory B3LYP/6-3IG（d） method. The first singlet excited state structures were optimized by virtue of singlet-excitation configuration interaction CIS/6-31G（d） method. The absorption and fluorescence emission spectra were then evaluated via the time-dependent density functional theory B3LYP and PBE1PBE methods with 6-31 l＋＋G（3df,2p） basis set. The calculation results show that compared with those of their parent molecules A-H, B-H, C-H, D-H, the absorption and emission wavelength values of all the derivatives show red shifts. The derivatives containing both the oxadiazole and methoxyl units are good candidates for longer absorption wavelength materials. The effects of azo, oxadiazole, and methoxyl units on the absorption and emission wavelength were discussed.

Luminescence Properties of Ca(NbO_3)_2∶Dy^(3+)

On the base of the luminescence properties of the Dy (3+) activated Ⅱ-Ⅴ group complex oxide,the luminescence properties of Ca(NbO_3)_2∶Dy (3+) and compensation effect by Na + for the Ca(NbO_3)_2∶Dy (3+) were introducted. The Dy (3+) concentrations in the phosphor powder of Ca(NbO_3)_2∶Dy (3+) and Ca(NbO_3)_2Na +∶Dy (3+) are different. The excitation spectrum,the emission spectrum and the blue-yellow ratios are obtained,and the spectrum law and the luminescence mechanism are also discussed.

PURIFICATION AND CHARACTERIZATION OF D_1-D_2-Cyt.b_(559) COMPLEX WITH THE ACTIVITY OF DCIP PHOTOREDUCTION FROM BROAD BEAN LEAVES

A PSII reaction center complex consisting of three polypeptides, D_1, D_2 and Cyt. b_(559), was first purified from broad bean leaves. The complex was fairly active inDCIP photoreduction in the presence of DPC, and showed signal Ⅱs either in the dark or under illumination. The complex also contained manganese atoms. Its Mn^(2+)-EPR intensity decreased by about 40% under continuous illumination and recovered to the original level when the complex was transferred to the dark. The above results indicated that the complex reported here contains all of the PSII electron transport chain components from the secondary donor Z to the stable primary electron acceptor Q_A, and it is possible that the complex contains manganese binding sites. The alternation in dark and illumination can induce reversible valence changes of the manganese atoms in the purified complex.