[Responses of soil ammonia-oxidizing microorganisms to simulated nitrogen deposition in a natural Castanopsis carlesii forest]. / äºšçƒ­å¸¦ç±³æ§ å¤©ç„¶æž—åœŸå£¤æ°¨æ°§åŒ–å¾®ç”Ÿç‰©å¯¹æ¨¡æ‹Ÿæ°®æ²‰é™çš„å“åº”.

Subtropical region of China is one of the global hotspots receiving nitrogen deposition. Nitrogen deposition could affect the abundance and community structure of ammonia oxidizers including ammonia-oxidizing bacteria (AOB), ammonia-oxidizing archaea (AOA) and complete ammonia oxidizer (comammox Nitrospira), with consequences on soil nutrient cycling that are driven by microorganisms. There is limited understanding for the newly discovered comammox Nitrospira in the subtropical forest soils. Here, we investigated the effect of simulated N deposition on abundances of soil ammonia oxidizers in the Castanopsis fargesii Nature Reserve in Xinkou Town, Sanming City, Fujian Province, China. Soil samples were collected from the field plots which received long-term nitrogen deposition with different dosages, including: CK, no additional treatment; LN, low nitrogen deposition treatment, dosage of 40 kg N·hm-2·a-1; and HN, high nitrogen deposition treatment, dosage of 80 kg N·hm-2·a-1. After 8-year treatment, simulated N deposition decreased soil pH and organic matter content, and increased nitrate content. We failed to amplify the amoA gene of AOB in the tested soils. High nitrogen deposition increased the abundance of AOA, but did not affect the abundance of comammox Nitrospira clade A and clade B. The ratio of comammox Nitrospira to AOA decreased with N addition, indicating that N addition weakened the role of comammox Nitrospira in nitrification in the subtropical forest soils. However, there were strong non-specific amplifications for both comammox Nitrospira clades A and B, highlighting the demand for the development of high coverage and specificity primers for comammox Nitrospira investigations in the future. The abundance of comammox Nitrospira clade A was positively correlated with total nitrogen (TN) and NH4+ concentration, while that of clade B was positively associated with soil organic carbon (SOC), TN and NH4+ Concentration. Overall, our findings demonstrated that simulated N deposition increased the relative importance of AOA in nitrification in the natural Castanopsis carlesii forest soil. These findings could provide theoretical support in coping with global change and N deposition in these regions.

[Characteristics of Bacterioplankton Community Between River and Lake/Reservoir in the Yangtze River Basin].

To explore the bacterioplankton community structure in the Yangtze River basin, water samples were collected from 177 sampling sites, including the source to the estuary along the mainstream of the Yangtze River, eight primary tributaries, and several lakes and reservoirs. The 16S rRNA genes were used to explore the bacterioplankton communities based on single molecule real-time sequencing, with the aim to study the diversity and community characteristics in a border sampling area and higher species annotation accuracy. Based on α-diversity analysis, the river area had higher species richness than that of the lake/reservoir area, resulting in these two areas having different bacterioplankton community diversities. Based on the ß diversity analysis, the bacterioplankton showed different community compositions between the river and lake/reservoir areas; temperature was the key environmental factor for the river area, and pH was the key environmental factor for the lake/reservoir area. In order to study the influence of different bacterioplankton communities, this study further investigated the species, function, and community differences between the river and lake/reservoir areas. The results were as follows:for the river area, the eutrophication level gradually increased from west to east along the mainstream of the Yangtze River, resulting in a gradually increased relative abundance of specific species. The lake/reservoir area had a higher risk of cyanobacteria bloom, and the opportunistic pathogen had a high relative abundance in the Danjiangkou Reservoir, indicating a higher ecological risk. For species composition, the river and lake/reservoir areas shared most OTUs (84%); however, some uncultured bacteria showed a high relative abundance in the Yangtze River, meaning the bacterioplankton of the Yangtze River basin still requires further study. In general, the river and lake/reservoir shared most species; however, the different bacterioplankton diversity, community composition, and enriched species made the river and lake/reservoir have different key environmental factors, and they also showed differences in ecological functions.

[Long-term effects of imbalanced fertilization with lime and gypsum additions on denitrifying functional genes of an Ultisol at Yingtan, Jiangxi, China]. / é•¿æœŸç¼ºç´ æ–½è‚¥åŠçŸ³ç°çŸ³è†æ–½ç”¨å¯¹æ±Ÿè¥¿é¹°æ½­çº¢å£¤åç¡åŒ–å¾®ç”Ÿç‰©åŠŸèƒ½åŸºå› ä¸°åº¦çš„å½±å“.

The abundance of denitrifying functional genes plays a key role in driving the soil nitrous oxide (N2O) emission potential. Nitrite reductase genes (nirK and nirS) and nitrous oxide reductase genes (nosZ I and nosZ II) are the dominant denitrifying funtional genes. In this study, real-time quantitative PCR was conducted to evaluate the effects of 32-year imbalanced fertilization and lime and gypsum additions on the abundances of nirK, nirS, nosZ I and nosZ II genes in an Ultisol at Yingtan, Jiangxi Province. We further explored the underlying driving factors. The results showed that, compared with the balanced fertilization treatment, fertilization without phosphorus (P) signifi-cantly decreased the abundances of nirK, nirS, nosZ I and nosZ II genes. Fertilization without nitrogen (N) significantly reduced the abundances of nirK, nosZ I and nosZ II, but did not affect the abundance of nirS. Fertilization without potassium (K) did not affect the abundances of all denitri-fying functional genes. Results of stepwise regression analysis and random forest analysis showed that soil pH was a key environmental factor affecting the abundances of nosZ I and nosZ II. The application of lime or lime + gypsum significantly increased soil pH, which subsequently increased the abundances of nosZ II and nosZ II/nosZ I by 150%-231% and 127%-155%, respectively. Our results suggested that application of lime or lime + gypsum favored nosZ II more than nosZ I in upland Ultisols, which might enhance the relative importance of nosZ II in N2O reduction. Overall, fertilization without P would reduce denitrifying gene abundances, while the application of lime or lime + gypsum enriched nosZ II and increased ratio of nosZ II/nosZ I, which might be beneficial for reducing N2O emission potential in the Ultisols.

[Responses of denitrifying functional gene abundance to long-term fertilization regimes in an upland Ultisol]. / æ—±åœ°çº¢å£¤åç¡åŒ–åŠŸèƒ½åŸºå› ä¸°åº¦å¯¹é•¿æœŸæ–½è‚¥çš„å“åº”.

Fertilization affects soil nitrogen cycling and nitrous oxide (N2O) emissions, which are mainly driven by microbes. A 32-year field experiment was conducted to investigate the effects of chemical fertilizers and their combination with organic materials on the abundance of denitrifying functional genes (nirS, nirK, nosZ I and nosZ II) in Ultisol. The treatments comprised no fertilizer (CK), chemical fertilizer, chemical fertilizer+peanut straw, chemical fertilizer+rice straw, chemical fertilizer+radish and chemical fertilizer+pig manure. Compared with the single chemical fertilizer treatment, soil pH and organic carbon content increased in the chemical fertilizer plus organic material treatments, with chemical fertilizer+pig manure having the strongest effect. Long-term fertilization did not affect the abundance of nirK gene, but significantly altered the nirS gene abundance. Compared to CK, long-term chemical fertilizer application increased the abundance of nirS gene by 426%. However, partial replacement of chemical fertilizer by organic materials decreased the abundance of nirS gene. The abundance of nosZ I gene was one order of magnitude higher than that of nosZ II, indicating the domination of nosZ I in the acidic Ultisol. Long-term fertilization did not affect the abundance of nosZ II, whereas chemical fertilizer+pig manure increased the abundance of nosZ I by 138%. Results of stepwise regression analysis showed that available phosphorus content was the primary factor regulating the abundance of nosZ I gene, whereas the abundance of the nosZ II gene was mainly regulated by nitrate content. Moreover, the lowest (nirS+nirK)/(nosZ I+nosZ II) value in the chemical fertilizer+pig manure treatment indicated that long-term manure application might reduce N2O emission potential in Ultisols.

Epidermal growth factor receptor mutations in plasma DNA samples predict tumor response in Chinese patients with stages IIIB to IV non-small-cell lung cancer.

PURPOSE: Mutations in the epidermal growth factor receptor (EGFR) kinase domain can predict tumor response to tyrosine kinase inhibitors (TKIs) in non-small-cell lung cancer (NSCLC). However, obtaining tumor tissues for mutation analysis is challenging. We hypothesized that plasma-based EGFR mutation analysis is feasible and has value in predicting tumor response in patients with NSCLC. PATIENTS AND METHODS: Plasma DNA samples and matched tumors from 230 patients with stages IIIB to IV NSCLC were analyzed for EGFR mutations in exons 19 and 21 by using denaturing high-performance liquid chromatography. We compared the mutations in the plasma samples and the matched tumors and determined an association between EGFR mutation status and the patients' clinical outcomes prospectively. RESULTS: In 230 patients, we detected 81 EGFR mutations in 79 (34.3%) of the patients' plasma samples. We detected the same mutations in 63 (79.7%) of the matched tumors. Sixteen plasma (7.0%) and fourteen tumor (6.1%) samples showed unique mutations. The mutation frequencies were significantly higher in never-smokers and in patients with adenocarcinomas (P = .012 and P = .009, respectively). In the 102 patients who failed platinum-based treatment and who were treated with gefitinib, 22 (59.5%) of the 37 with EGFR mutations in the plasma samples, whereas only 15 (23.1%) of the 65 without EGFR mutations, achieved an objective response (P = .002). Patients with EGFR mutations had a significantly longer progression-free survival time than those without mutations (P = .044) in plasma. CONCLUSION: EGFR mutations can be reliably detected in plasma DNA of patients with stages IIIB to IV NSCLC and can be used as a biomarker to predict tumor response to TKIs.