[Distribution Characteristics of Near Surface Ozone Volume Fraction in Shanxi Province Based on Atmospheric Composition Observation Network].

Based on the continuous data of O3， NO， NO2， and NOx and the meteorological data from March 2019 to February 2020 at six atmospheric composition observation stations in Shanxi Province， the characteristics and influence factors of O3 volume fractions were studied using statistical analysis and backward trajectory analysis. The results showed that O3 volume fractions were generally higher from April to September and lower from October to the following March. During the study period， O3 pollution represented by φ（MDA8O3）， i.e.， the maximum daily 8-h average of O3 volume fractions， was the most serious at the Jincheng and Linfen stations in the south of Shanxi， followed by that in the Wutaishan， Shuozhou， and Datong stations in the north， with the least pollution occurring at the Taiyuan station in the middle. There were differences between the urban and alpine stations， although their seasonal O3 volume fractions were both summer > spring > autumn > winter. O3 volume fractions at the urban station were usually lower than those at the alpine station； O3 at the urban station might have been influenced by photochemical reactions with precursor NOx； however， this was not the main source of high O3 at the alpine station. The peak and valley values appeared at 15：00 and 06：00， respectively， at the urban station， whereas they appeared at 20：00 and 10：00， respectively， at the alpine station， representing diametrically opposite diurnal variation patterns. Further， the daily amplitude of O3 at the urban station was much larger than that at the alpine station. For urban stations specifically， temperature was the most important meteorological factor affecting O3 volume fraction， compared with sunlight hours， precipitation， and total cloud cover. The NO2 volume fraction in the daytime affected the daily amplitude of O3； although the photochemical generation potential of O3 at the Taiyuan station was good， the O3 volume fractions were the lowest among urban stations due to strong NO titration. The higher O3 corresponded to lower NOx in which NO2 was dominant， and the higher NOx was largely composed of NO， under which conditions O3 would be depleted completely. The surface wind that affected O3 volume fractions of all stations primarily came from the southeast， south， and southwest， and specific wind speed led to the increase in O3 volume fraction. The geographical situation of the station would cause the difference in the transport of atmospheric pollutants， whereas the horizontal transmissions of high O3 from the North China Plain and Fenwei Plain were likely to be the common reason for the increase in O3 volume fraction in Shanxi.

Overexpression of a New Zinc Finger Protein Transcription Factor OsCTZFP8 Improves Cold Tolerance in Rice.

Cold stress is one of the most important abiotic stresses in rice. C2H2 zinc finger proteins play important roles in response to abiotic stresses in plants. In the present study, we isolated and functionally characterized a new C2H2 zinc finger protein transcription factor OsCTZFP8 in rice. OsCTZFP8 encodes a C2H2 zinc finger protein, which contains a typical zinc finger motif, as well as a potential nuclear localization signal (NLS) and a leucine-rich region (L-box). Expression of OsCTZFP8 was differentially induced by several abiotic stresses and was strongly induced by cold stress. Subcellular localization assay and yeast one-hybrid analysis revealed that OsCTZFP8 was a nuclear protein and has transactivation activity. To characterize the function of OsCTZFP8 in rice, the full-length cDNA of OsCTZFP8 was isolated and transgenic rice with overexpression of OsCTZFP8 driven by the maize ubiquitin promoter was generated using Agrobacterium-mediated transformation. Among 46 independent transgenic lines, 6 single-copy homozygous overexpressing lines were selected by Southern blot analysis and Basta resistance segregation assay in both T1 and T2 generations. Transgenic rice overexpressing OsCTZFP8 exhibited cold tolerant phenotypes with significantly higher pollen fertilities and seed setting rates than nontransgenic control plants. In addition, yield per plant of OsCTZFP8-expressing lines was significantly (p < 0.01) higher than that of nontransgenic control plants under cold treatments. These results demonstrate that OsCTZFP8 was a C2H2 zinc finger transcription factor that plays an important role in cold tolerance in rice.

Reaction pattern of Bacillus cereus D-11 chitosanase on chitooligosaccharide alcohols.

The purified endochitosanase (Mw 41 kDa) from bacterium Bacillus cereus D-11 hydrolyzed chitooligomers (GlcN)5-7 into chitobiose, chitotriose, and chitotetraose as the final products. The minimal size of the oligosaccharides for enzymatic hydrolysis was a pentamer. To further investigate the cleavage pattern of this enzyme, chitooligosaccharide alcohols were prepared as substrates and the end products of hydrolysis were analyzed by TLC and HPLC. The chitosanase split (GlcN)4GlcNOH into (GlcN)3+ (GlcN)1GlcNOH, and (GlcN)5GlcNOH into (GlcN)4+ (GlcN)1GlcNOH and (GlcN)3+(GlcN)2GlcNOH. The heptamer (GlcN)6GlcNOH was split into (GlcN)5 [thereafter hydrolyzed again into (GlcN)3+(GlcN)2]+(GlcN)1GlcNOH, (GlcN)4+(GlcN)2GlcNOH, and (GlcN)3+(GlcN)3GlcNOH, whereas (GlcN)1-3GlcNOH was not hydrolyzed. The monomers GlcN and GlcNOH were never detected from the enzyme reaction. These results suggest that D-11 chitosanase recognizes three glucosamine residues in the minus position and simultaneously two residues in the plus position from the cleavage point.