UV-B radiation increased the sensitivity of Tibetan soil cyanobacterium Loriellopsis cavernicola to the herbicide glyphosate.

The high concentrations of herbicide and UV-B radiation are two stresses for Tibetan soil microorganisms, but there is limited information about the combined effects of herbicide and UV-B radiation on their levels of stress. In this study, the Tibetan soil cyanobacterium Loriellopsis cavernicola was used to investigate the combined inhibitory effect of the herbicide glyphosate and UV-B radiation on the cyanobacterial photosynthetic electron transport through an analysis of the photosynthetic activity, photosynthetic pigments, chlorophyll fluorescence and antioxidant system activity. The results demonstrated that treatment with herbicide or UV-B radiation and the combination of both stresses caused a decrease in the photosynthetic activity, interfered with the photosynthetic electron transport, and caused the accumulation of oxygen radicals and the degradation of photosynthetic pigments. In contrast, the combined treatment of glyphosate and UV-B radiation had a synergistic effect, i.e., the sensitivity of cyanobacteria to glyphosate increased in the presence of UV-B radiation, which caused the photosynthesis of cyanobacteria to have a greater impact. Since cyanobacteria are the primary producers of soil ecosystems, a high intensity of UV-B radiation in the plateau areas could enhance the inhibition of glyphosate on cyanobacteria, which could affect the ecological health and sustainable development of plateau soils.

Photosynthesis Responses of Tibetan Freshwater Algae Chlorella vulgaris to Herbicide Glyphosate.

With the development of agriculture and the widespread application of agrichemicals in Tibet, herbicide residues have become a threat to the ecological safety of Tibetan water bodies. Algae, as the producers in the food chain in water bodies, play an important role in aquatic ecosystems. Therefore, the impact of herbicides on Tibetan algae is of great significance for evaluating ecological health and the protection of Tibetan water ecosystems. In this study, we investigated the inhibitory effect of glyphosate, a herbicide, on the photosynthetic system of Chlorella vulgaris, Tibetan algae, by determining chlorophyll fluorescence and the activity of an antioxidant system. The results revealed that glyphosate at low concentration did not affect the photosynthetic activity of C. vulgaris; however, glyphosate at a high concentration significantly inhibited photosynthetic activity and reduced pigment content. Moreover, high levels of glyphosate also decreased photochemical efficiency and electron transport rate and resulted in ROS accumulation, high SOD activity, and lipid peroxidation. These results suggested that glyphosate could decrease the primary production of aquatic ecosystems and influence their performance. Therefore, reducing the herbicide levels could protect the Tibetan aquatic environment and maintain the health of ecosystems.

Relationship between onset of peptic ulcer and meteorological factors.

AIM: To discuss the relationship between onset of peptic ulcer (PU) and meteorological factors (MFs). METHODS: A total of 24,252 patients were found with active PU in 104,121 samples of gastroscopic examination from 17 hospitals in Nanning from 1992 to 1997. The detectable rate of PU (DRPU) was calculated every month, every ten days and every five days. An analysis of DRPU and MFs was made in the same period of the year. A forecast model based on MFs of the previous month was established. The real and forecast values were tested and verified. RESULTS: During the 6 years, the DRPU from November to April was 24.4 -28.8%. The peak value (28.8%) was in January. The DRPU from May to October was 20.0-22.6%, with its low peak (20.0%) in June. The DRPU decreased from winter and spring to summer and autumn (P<0.005). The correlated coefficient between DRPU and average temperature value was -0.8704, -0.6624, -0.5384 for one month, ten days , five days respectively (P<0.01). The correlated coefficient between DRPU and average highest temperature value was -0.8000,-0.6470,-0.5167 respectively (P<0.01). The correlated coefficient between DRPU and average lowest temperature value was -0.8091, -0.6617, -0.5384 respectively (P<0.01). The correlated coefficient between DRPU and average dew point temperature was -0.7812, -0.6246, -0.4936 respectively (P<0.01). The correlated coefficient between DRPU and average air pressure value was 0.7320, 0.5777, 0.4579 respectively (P<0.01). The average temperature, average highest and lowest temperature, average air pressure and average dew point temperature value of the previous month, ten days and five days could forecast the onset of PU, with its real and forecast values corresponding to 71.8%, 67.9% and 66.6% respectively. CONCLUSION: DRPU is closely related with the average temperature, average highest and lowest temperature,average air pressure and average dew point temperature of each month, every ten days and every five days for the same period. When MFs are changed, the human body produces a series of stress actions.A long-term and median-term based medical meteorological forecast of the onset of PU can be made more accurately according to this.

A new kinetic method for quantification phenoxyl free radicals.

In this work, a new kinetic method was proposed for quantification phenoxyl radicals generated in enzyme reaction. Instead of direct detecting the spectral signals of phenoxyl radicals, a molecular probe, the reduced form of nicotinamide adenine dinucleotide (NADH), was employed to indicate the formation of phenoxyl free radicals. It was found that the reactions of NADH and phenoxyl radicals are very fast, but can be followed by using stopped-flow fast scanning spectrophotometric technique. The initial rate of accelerated-oxidation of NADH represents the reactivity of phenoxyl free radical, which is proportional in a certain range to the initial concentration of the parent chlorophenols of the radicals. With this method, the phenoxyl radicals generated in oxidation reaction of chlorophenols (2-CP; 4-CP; 2,4-DCP; 2,4,6-TCP and 2,3,4,6-Tetra-CP) with hydrogen peroxide, catalyzed by horseradish peroxidase, were investigated. The method is highly sensitive. Phenoxyl radicals generated from as low as 1x10(-8)M 2,4-DCP, for example, can be readily detected with the proposed method. The results show that the reactivity of various phenoxyl radicals are in the following order: 2,4-DCP>4-CP>2-CP>2,4,6-TCP>2,3,4,6-Tetra-CP. A mechanism is proposed to explain the possible pathway of the probe reaction. The feasibility of this method was assessed by the determination of enzymatic generation of phenoxyl radicals in lake water samples.

Fluorometric assay of tiopronin based on inhibition of multienzyme redox system.

In this paper, a simple and sensitive fluorimetric method for the determination of tiopronin (N-(2-mercaptopropionyl)-glycine) is proposed. The method is based on the strong inhibitory effect of tiopronin on the multienzyme redox system of hemoglobin, nicotinamide adenine dinucleotide (NADH) and H(2)O(2), in which the intrinsic fluorescence of NADH was employed as the detection signal. The calibration graph is linear in the range 6.13 x 10(-7) to 6.13 x 10(-6) M with a detection limit of 1.65 x 10(-7) M and the relative standard deviation of 2.02%. Kinetics in the pseudo-first-order conditions was investigated by stopped-flow spectrofluorometry and the inhibition mechanism of tiopronin was verified of the competitive type.