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The interaction mechanism of nucleic acid with small organic molecules plays an important role in the recognition of the structure and function of nucleic acids, which can also reveal the biological function of nucleic acids and the mechanism of some drugs. Research on the interaction between nucleic acid and small organic molecules plays an important part in simulating the life process and exploring the essence of life. In the present article, detailed description of the fluorescence spectroscopy research methods used in this field is presented. The fluorescence quenching types of the interaction between nucleic acid and small organic molecules (including dyes and drugs) are discussed. There are many factors influencing the fluorescence quenching type, including the temperature, the rate constant of bimolecular quenching process, the fluorescence lifetime, changes of the absorption spectra and so on. So according to different affecting factors, the fluorescence quenching type can be determined based on corresponding theories. Many different kinds of calculation methods are also summarized, including the calculations of the binding constant, the distance between fluorescence donor and receptor, the interaction force type and the binding mode of nucleic acid with small organic molecules. Furthermore, the formation constant of nucleic acid with small organic molecules is studied with different binding numbers. These conclusions have guiding significance for studying the interaction between nucleic acid and small organic molecules. These results can also provide guidance for the development of new nucleic acid probe, and the design of new drug molecules, of which nucleic acid is the important target.

Responses of a select suite of protective enzymes in Lateolabrax japonicus including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (Gpx), reduced glutathione (GSH) glutathione S-transferase (GST), nitric oxide synthase (iNOS) in liver tissue and brain acetylcholinesterase (AChE), which could work as sensitively biochemical biomarkers were analyzed when exposed to different concentrations of sodium dodecylbenzene sulfonate (SDBS) and benzo[a]pyrene (B[a]P) under controlled laboratory conditions. Results showed that: (1) The biochemical biomarkers included in this investigation, different responses occurred in the enzymatic activities when exposed to different pollutants: the activities of SOD, GST, Gpx and GSH content were significantly induced by B[a]P (p < 0.05) while others present little different as compared to the control. Differently, SDBS exposure greatly affected the activities of CAT, Gpx, iNOS and AChE while showed little effect on the other evaluated biomarkers. Gpx was the most sensitive biomarker that sensitively indicated the organic pollution stress. (2) The simultaneous assay on heat shock protein 70 (Hsp70) expression was conducted by flow cytometry (FCM) and result presented that Hsp 70 expression could be effectively induced by SDBS as compared to the control throughout the experiment; however, B[a]P obviously induced Hsp70 during the first 12 d and then decreased to the level of the control. (3) The evaluated method of biomarker system combined with principal component analysis (PCA) could effectively distinguish different pollutants under controlled laboratory conditions and might be a promising and warning method for the early assessment of environmental change exposed to different organic pollutions.

The reaction of 2,4,6-tri(2-pyridyl)-1,3,5-triazine (TPTZ) with RECl3 in ethanol solution was studied. Seven solid coordination compounds of rare earth were synthesized. Their elemental analysis, rare earth complexometric titration, molar conduction, TG-DTA curve, IR spectra and UV spectra were studied. The results suggest that the composition of the complexes was RE(TPTZ)C13 x 3H2O(RE = Sm, Eu, Tb, Dy) and Tb0.5Ln0.5 (TPTZ)Cl3 x 3H2O(Ln = Gd, Y, La), where TPTZ acts as a tridentate ligand with rare earth ion, the rare earth ion is eight-coordinate being bonded to the tridentate TPTZ, two Cl- anions and three water molecules, and the complexes-bounded may be [RE(TPTZ) (H2O)3Cl2] x Cl and [(Tb0.5 Ln0.5) (TPTZ) (H2O)3Cl2] x Cl. They are all 1 : 1 electrolytes in the DMF. The fluorescence spectra of the complexes were determined at room temperature. The results show that the fluorescence intensity of Tb3+ complex is the strongest among the four (Eu3+, Sm3+, Tb3+ and Dy3+) complexes. The lowest excitation state energy level of Tb3+ ion and the triplet state energy level of the ligand (TPTZ) match well. The absorbing energy of the ligand is effectively transferred to Tb3+ ion. The fluorescence intensity of terbium doped complexes (Tb3+ mixed by Gd3+, Y2+ and La3+) is stronger than that of terbium complex, showing that the fluorescence intensity of Tb3+ ion is raised by Gd3+, Y3+ and La3+ ions.

In the title compound, C(21)H(20)O(3), the two terminal phenyl rings are each approximately perpendicular to the central benzene ring, making dihedral angles of 84.40 (16) and 75.12 (15)°. The H atom of the hydr-oxy group is disordered over two positions with equal occupancies. The mol-ecules are linked by O-H⋯O hydrogen bonds, forming a chain along the a axis.

The effects NaH2PO4, adenosine disodium triphosphate (ATP), glucose 6-phosphate (G-6-P) and sodium beta-glycerophosphate (G-P) on the growth and phosphatase activity of Skeletonema costatum and Prorocentrum donghaiense were studied. The results showed that both species could utilize both dissolved inorganic phosphate (DIP) and dissolved organic phosphorus (DOP), and DOP had more effects on the growth of two species than DIP. For S. costatum, after 8 days, the cell abundances of the four treatments (NaH2PO4, ATP, G-6-P and G-P) were 48 x 10(4), 73 x 10(4), 63 x 10(4) and 54 x 10(4) cells/mL, respectively; For P. donghaiense, after 10 days, the cell abundances of the four treatments were 8.7 x 10(4), 15.5 x 10(4), 12.4 x 10(4) and 9.5 x 10(4) cells/mL, respectively. On the first 3-4 days, the phosphatase activity of all treatments of the two species showed a decreasing trend, but different changes were observed for the different phosphorus substrate treatments in latter days. For the NaH2PO4 treatment, both the AP and AcP activity of two species increased from the fifth day onwards. For S. costatum, the AP activity of the ATP and G-6-P treatment groups showed no obvious changes and AcP activity had a slight increase from the fifth day to the eighth day, while the activity of G-P treatment had highest phosphatase activity which increased from the fifth day on. At the end of the experiment, the AP activity of the three DOP treatment groups (ATP, G-6-P and G-P) was 0.004 x 10(-5), 0.014 x 10(-5) and 0.029 x 10(-5) U/cell, respectively, and the AcP activity was 0.006 x 10(-5), 0.011 x 10(-5) and 0.018 x 10(-5) U/cell, respectively. For P. donghaiense, both the AP and AcP activity of the three DOP treatments had similar trends, i.e., ATP < G-6-P < G-P. Under the same nutrient conditions, S. costatum had a much higher phosphatase activity and could absorb P from the environment much faster than P. donghaiense.

The contents of cellular chlorophyll a (Chl-a), chlorophyll c (Chl-c), total coloured carotenoids (TCC) and the photosynthesis of Skeletonema costatum and Prorocentrum donghaiense under different nutrient conditions were studied. The results showed that both species in the low nutrient concentration conditions had lower cellular Chl-a, Chl-c and TCC content than those in the high nutrient concentration conditions. When the initial N/P ratio was 16/1 while the concentrations were different, the two species had different photosynthetic rate responses. For S. costatum, the photosynthetic rate normalized by cell in the low nutrient concentration group (64 micromol/L N and 4 micromol/L P) was significantly lower than that in the high concentration group (256 micromol/L N and 16 micromol/L P) from the fifth day, and at the end of the experiment (on the seventh day), the photosynthetic rate was 0.031 x 10(-4) micromol x (cell x h)(-1) and 0.13 x 10(-4) micromol x (cell x h)(-1) respectively, while the photosynthetic rate normalized by Chl-a was 12.92 micromol x (microg x h)(-1) and 13.03 micromol x (microg x h)(-1) for the two groups respectively, and there was no significant difference between them; however, for P. donghaiense, the photosynthetic rates normalized by both cell and Chl-a in the low concentration conditions (64 micromol/L N and 4 micromol/L P) were significantly higher than those in the high concentration conditions (256 micromol/L N and 16 micromol/L P). For the two species, when P was sufficient, the low N concentration group (64 micromol/L N and 36 micromol/L P) and when N was sufficient, the low P concentration group (883 micromol/L N and 4 micromol/L P) had higher photosynthetic rates normalized by both cell and Chl-a than the high N concentration group (256 micromol/L N and 36 micromol/L P) and the high P concentration group (883 micromol/L N and 16 micromol/L P) respectively. There was a significant positive relationship between the photosynthetic rate and the intracellular P for both species, and P. donghaiense had higher cellular photopigment contents and photosynthetic rates than S. costatum under the same nutrient conditions. It could be inferred from their photosynthetic characteristics that P. donghaiense would survive better in low nutrient conditions compared with S. costatum.