Assessment of heavy metal pollution and health risks in a main river in Huayuan County,Xiangxi, Hunan Province北大核心CSCD

To study heavy metal pollution and assess the health risk of river water in Huayuan County, Xiangxi, Hunan Province, 11 water samples were collected from the Huayuan River and Brother Rivers in August and December 2016. Heavy metal (Pb, Zn, Cr, Cu, Fe, and Ni) concentrations were determined from the samples. The health risk assessment model recommended by the U.S. Environmental Protection Agency (USEPA) was applied to assess the health risk of heavy metals in the main surface waters of Huayuan County. The results indicated that the concentrations of heavy metals (Pb, Zn, Cr, Cu, Fe, and Ni) of surface water in the research area were 2.57 × 10-3, 4.66 × 10-4, 1.65 × 10-3, 6.27 × 10-4, 0.19, and 8.50 × 10-4 mg/L, respectively. The health risk of surface waters with heavy metals was high. Therefore, the chemical carcinogenic substance (Cr) health risk index was five or six times higher than that of chemical non-carcinogens (Pb, Zn, Cu, and Ni). The average health risk indices of non-carcinogenic substances were in the order Pb > Cu > Zn > Ni. The correlation and principal component analysis of surface water showed that the six heavy metal elements were composed of three main components in the main surface waters of the county. The first principal component was comprised of Fe and Ni (33.28%), which was mainly from internal pollution. The second component was comprised of Cu and Cr (26.98%), which was primarily due to industrial waste water, rainwater leaching mineral waste produced by heavy metal mining, and smelting enterprises. The third component, resulting from geochemical pollution, was Zn (17.10%). The health risk indices triggered by heavy metal in surface waters was high. Heavy metal pollutants in the research area need to be controlled in the order Cr, Pb, Cu, Zn and Ni. © 2018 Science Press. All rights reserved.     

Spatial distribution and risk assessment of soil heavy metal contamination along roadsides of the northwestern Sichuan Plateau,China北大核心CSCD

Traffic activities in roadways are the major source of heavy metal contamination on the northwestern Sichuan Plateau, China. To characterize the spatial pattern of heavy metal distribution, we collected soil samples and measured the concentrations of five heavy metals (Cd, Cu, Ni, Pb, and Zn) from nine sites in Hongyuan County, Sichuan Province, including three transects that reflected typical gradients of traffic density. Each transect consisted of three levels of traffic density sites. We calculated single pollution index, Nemerow multi-factor index, and potential ecological risk index, to assess the ecological risk of the heavy metal contamination. Results showed that the soils were contaminated by Cd and Zn, with higher concentrations than that of the natural soil background values in all sampling sites. Moreover, Cd and Zn concentrations increased with increasing traffic density, suggesting that traffic activities were potentially responsible for the metal contaminations. The single pollution index indicated that the study sites were heavily contaminated by Cd and slightly polluted by Ni, Pb, and Zn, and the Nemerow multi-factor and potential ecological risk indexes indicated moderate potential ecological risks at the study sites. Specifically, the sites with high traffic density were moderately contaminated and the sites with low traffic density were mildly contaminated. In general, Cd and Zn were highly accumulated in soils of the study region; therefore focus should be on the high ecological hazard associated with soil heavy metal contamination, even in undeveloped regions. © 2018 Science Press. All rights reserved.     

Isolation,identification, and biological characteristics of a wild Chaga mushroom北大核心CSCD

In this study, a pure culture strain (numbered as F1501) was obtained using tissue separation and purification methods from the sclerotia of Chaga mushroom from Russia. Further researches included studies on classification, optimum growth conditions of mycelia, extracellular polysaccharides from fermentation broth and their antioxidant activity, and artificial acclimation. According to the identification of the internal transcribed spacer (ITS) region, it was confirmed that F1501 was a species of the genus Inonotus and family Hymenochaetaceae, which had 99% similarity with Inonotus obliquus. F1501 was further classified as I. obliquus based on the morphological characteristics of its mycelia and sclerotia. The optimal carbon source, nitrogen source, C/N ratio, growth factor, temperature, and pH value for the growth of the F1501 strain mycelia were maltose, beef extracts, 10/1, B2, 28 °C, and 8.0, respectively. Liquid fermentation of F1501 was performed using PD media and a 10% inoculation amount at 28 °C and 150 r/min for 7 d. The content of polysaccharides in the fermentation broth was 476.32 mg/L, with a total antioxidant activity of 0.19 mmol/L (Trolox) and hydroxyl free radical-scavenging activity of 72.7%. Artificial acclimation study revealed that the fruiting body-like structure was obtained using cottonseed hulls as the main substrate. In the present study, a new strain of I. obliquus and its biological characteristics were explored, which could provide a theoretical basis for the artificial acclimation and development of wild mushrooms. © 2018 Science Press. All rights reserved.     

Growth release and growth inhibition of Pinus tabulaeformis forest in the Loess Plateau of western Shanxi Province,China北大核心CSCD

There has been increased focus on the impacts of climate change on vegetation growth, and human activities that interfere with the vegetation. Discussing the effects of climate change and thinning activity on forest growth is essential to expand plantation areas. In this study, the dendroecological method was used to analyze the radial growth of Pinus tabulaeformis to reveal the impacts of climate change and human activities on forest stand growth. These samples were derived from three different density areas of P. tabulaeformis forest at the Linfen City of Shanxi Province (the east of Loess Plateau). The correlation analysis between tree ring width index and climatic factors indicated that the growth of P. tabulaeformis was negatively related to precipitation in January and the monthly maximum temperature in December of the previous year, whereas positively correlated with precipitation in July and the monthly maximum temperature in October in that year. The phenomena of growth release and inhibition could be attributed to the impacts of climate change and thinning during 1978-2003. However, growth inhibition was closely related to unsuitable climatic conditions. Plot 1 showed a moderate growth inhibition period when the growth variation was less than -50%, and growth release was caused by thinning. The growth variation was greater than 47% in the period of growth release. Moreover, a slight growth release occurred due to tending in plot 2, and the rate of growth change exceeded 39%. A slight growth suppression induced by uncomfortable climatic condition caused growth variation less than -32% and a moderate growth release by the interaction of cutting and comfortable counterpart made variation rate larger than 75% in plot 3. The release effects of thinning can last for about 5 years. In summary, inappropriate climatic conditions can inhibit the growth of trees, and thinning can promote tree growth by about 5 years. The results can provide a reference for local forest management. © 2018 Science Press. All rights reserved.     

Effects of a lead- and cadmium-resistant fungal strain on the absorption of heavy metals by Vetiveria zizanioides北大核心CSCD

A two-factor randomized complete block experiment was used to explore the remediation by a plant-microorganism combination on soils contaminated by lead (Pb) and cadmium (Cd). Factor A was the amount of fungi, for which four values were considered, namely, 0, 1, 3, and 5 g. Factor B was the level of contamination by lead and cadmium, for which six values were considered, namely, Cd0Pb0, Cd10Pb400, Cd20Pb600, Cd30Pb800, Cd50Pb1200, and Cd80Pb1800 (data in units of mg/ kg). The results showed that the resistant fungi promoted the growth of vetiver (Vetiveria zizanioides). At weights of 1, 3, and 5 g, the resistant fungi increased the biomass of vetiver by 41.9%, 74.9%, and 71.7% respectively. The resistant fungi stimulated the absorption of lead and cadmium by both the aerial and underground parts of vetiver. In the presence of 80 mg/kg of Cd2+ and 1 800 mg/kg of Pb2+, the contents of lead in the aerial parts of vetiver were increased by 120.6%, 265.4%, and 242.9%, while the lead content in the underground parts were increased by 110.3%, 278.2%, and 266.2%, after the addition of 1 g, 3 g, and 5 g of fungi, respectively. The content of cadmium in the aerial parts increased by 113.2%, 238.3%, and 217.3%, while the content of cadmium in the underground parts increased by 103.1%, 298.8%, and 274.4%, after the addition of 1 g, 3 g, and 5 g of fungi, respectively. The addition of fungi strengthened the effect of V. zizanioides to remediate soils contaminated by lead and cadmium, and the remediation after the addition of 3 g of fungi was better than that after treatment with 1 g and 5 g of fungi. The combination of resistant fungi and the heavy metal enrichment plant, vetiver, under different concentrations of lead and cadmium showed that the fungi had a significant effect on the remediation of soils contaminated by lead and cadmium. © 2018 Science Press. All rights reserved.     

Ecological stoichiometric characteristics of carbon,nitrogen, and phosphorus in three forests in the Lüliang Mountainous Area of Shanxi Province北大核心CSCD

Using a standard plot method, the stoichiometry of carbon (C), nitrogen (N), and phosphorus (P) in leaves, litter, and soil (0-20 cm depth) was investigated for three forest types: Populus davidiana, Larix principis-rupprechtii, and Pinus tabuliformis. The results showed that the stoichiometry of C, N, and P of the same component in the three forests were significantly different. The C and N contents in leaves, litter, and soil in P. davidiana forest were higher than those in L. principis-rupprechtii and P. tabuliformis forests were. However, P in the L. principis-rupprechtii forest was higher than that in the P. davidiana forest and P. tabuliformis forests were. The C, N, and P contents of the components in the three forests were, in order, leaves > litter > soil, and the three nutrient contents were significantly higher in leaves and litter than they were in soil. C:N and C:P in the three forests exhibited a trend of litter > leaves > soil, whereas that for N:P was leaves > soil > litter. There were highly significant positive relationships in N:P between the litter and the soil in the P. davidiana forest. Leaf C:N and litter C:P in the L. principis-rupprechtii forest were significantly negatively correlated, whereas N:P in the leaves and soil was positively correlated. There was a significant positive correlation in N:P between the leaves and the soil in the P. tabuliformis forest. In conclusion, the N contents in leaves and soil exhibited a significant positive correlation, whereas there was no significant correlation between C, N, and P in litter or soil. Environmental factors had a large influence on the stoichiometry of C, N, and P in soil. In particular, latitude and altitude had the most significant effects on C, N, P, C:N, and C:P and were significantly p ositively correlated. T hese results provide a scientific basis for f urther studies on nutrient utilization a nd t he cyclic characteristics of different forests in this area. © 2018 Science Press. All rights reserved.     

Isolation,identification, and the biodegradation characteristics of a benzoylurea insecticides-degrading strain北大核心CSCD

A chlorbenzuron, diflubenzuron, and hexaflumuron-degrading bacterium strain M6, was isolated from the activated sludge of an insecticide factory. The strain was identified as Achromobacter sp. according to an analysis on the 16S rRNA gene sequences, morphological, and physiological characteristics. Strain M6 could degrade more than 91% of 100 mg/L chlorbenzuron, diflubenzuron, and hexaflumuron within 48 hours, which could act as the sole carbon source. Strain M6 showed more chlorbenzuron degradation at a temperature range between 25 and 40 ℃ and a pH range between 6.0 and 8.0. The optimal temperature and the initial pH of medium for chlorbenzuron degradation by strain M6 were 30 ℃ and 7.0, respectively; the maximum chlorbenzuron tolerated concentration of strain M6 was as high as 400 mg/L. Strain M6 hydrolyzed 4-acetaminophenol into a purple-red product. Moreover, an approximately 1.4 kb DNA fragment, which could be expressed into an amidase to degrade amide pesticides, was amplified from the genomic DNA of strain M6. The results preliminarily proved that 3 benzoylurea insecticides could be degraded because of strain M6 hydrolyzing their amide bonds. This study obtained a highly efficient degrading strain and provided new resources and valuable information on benzoylurea insecticide degradation. © 2018 Science Press. All rights reserved.     

Effect of soil acidification on yield and quality of tea tree in tea plantations from Anxi county,Fujian Province北大核心CSCD

In order to investigate the effect of tea tree rhizosphere soil acidification on yield and quality of tea tree, the pH value, yield, and quality index of fresh tea leaves of different ages were analyzed, and the correlation between rhizosphere soil acidification and ages, yield, and quality index were studied from nine tea plantations in Anxi county, Fujian Province. The results showed that 37.67% of the nine soils were acidified, and 10.03% of them were suitable for planting tea tree. Furthermore, the results indicated that the age of tea tree was significantly and negatively correlated with the soil pH value, as shown by a decrease in soil pH values associated with an increase in tree age. In addition, the yield of spring and fall crops of tea from these nine plantations were all significantly and positively correlated with the pH value, with correlation coefficients distribution values of 0.912-0.952 and 0.898-0.973, respectively. In addition, quality indices, including polyphenols, theanine, and caffeine for the nine tea plantations were all significantly and positively correlated with their soil pH values, and their correlation coefficient distribution values were 0.897-0.959, 0.908-0.974, and 0.907-0.975, respectively. Above all, as tea tree ages increased, rhizosphere soil acidity was significantly increased, and yield and quality of tea presented a statistically significantly up/down trend. © 2018 Science Press. All rights reserved.     

Screening and degradation characteristics of a tetracycline-degrading bacterial strain北大核心CSCD

Tetracycline is widely used in livestock and poultry breeding industry, which can cause serious problems to the environment. Antibiotic pollution has become an important environmental issue. This study aimed to isolate and identify a well-functioning tetracycline-degrading bacteria strain from activated sludge and to investigate its optimum degradation conditions. The strain was identified through morphological features, Gram staining, and the sequence analysis of 16S rRNA. Furthermore, the temperature, initial pH of the medium, inoculation amount, and type of metallic salt were analyzed to investigate the tetracycline degradation performance of the isolated strain. Based on the single factor test, the method of response surface analysis was adopted to optimize the degradation condition. The strain was named TTC-1 and identified as Klebsiella pneumoniae. The optimum condition for tetracycline degradation was determined as follows: temperature of 34.4 °C, pH of 7.22, and MnSO4 concentration of 0.32 g/L. Under this optimum condition, the predicted tetracycline degradation rate was 93.77%, whereas the observed value was 94.26%. The experimental results showed that the proposed model had high accuracy. TTC-1 showed a good performance in degrading tetracycline, which can provide reference for the bacteria during the biological treatment of tetracycline containing wastewater. © 2018 Science Press. All rights reserved.     

Isolation,identification, culture conditions,and laccase production of a wild mushroom 'Huaier'北大核心CSCD

In the present study, fruiting bodies of a wild medicinal mushroom, 'Huaier, ' were collected from Populus canadensis in the Beijing Xiangshan Park. The pure culture strain was obtained from fruiting bodies using the tissue isolation method. It was stored and numbered as XS-01. It was systematically classified using morphological and ITS identification. Further studies were focused on mycelia optimum culture conditions and laccase production by liquid fermentation. A 598-bp partial ITS region sequence (GenBank accession number KY93348) was obtained using PCR method. Phylogenetic tree and genetic distance analysis were performed using the MEGA 6.0 software. The present strain possessed the highest homology (100%) with Perenniporia robiniophila, and the genetic distances were 0.000. Based on the ITS sequencing and morphological characteristics of fruiting bodies and mycelia, XS-01 was identified as P. robiniophila. Based on mycelial growth rate and quality, mycelia optimum culture conditions were revealed to be as follows: the optimum carbon sources were starch and maltose, the optimum nitrogen source was yeast extracts, the optimum C/N ratio range was 30/1 - 60/1, the best growth temperature was 32 °C, the optimum pH was 7, and the optimum growth factor was VB1. Further study of Cu2+ on extracellular laccase production revealed that 1.0 mmol/L Cu2+ could significantly enhance the enzyme production, with the highest activity of 417.5 U/mL when cultured for 96 h and an increase ratio of 93.4% to the control. On the other hand, 2.0 mmol/L Cu2+ can markedly decrease the enzyme production laccase activity at 96 h to 79.0 U/mL, which was 36.6% of that of the control. In conclusion, a pure strain of T. robiniophila with high extracellular laccase activity was obtained, suggesting its potential application for artificial cultivation and laccase production. © 2018 Science Press. All rights reserved.     

Isolation,identification, and the degradation characteristics of a BDE-47 degrading strain北大核心CSCD

In an effort to remove BDE-47 residues from the environment, a bacterial strain that is capable of utilizing BDE-47 as the sole carbon source was isolated and screened from soil collected from an e-waste recycling area in Tianjin to analyze the degradation properties. The strain was preliminarily identified as Enterobacter sp. according to a 16S rDNA gene sequence analysis. The strain degraded 35.8% of 525 μg/L of BDE-47 in 35 d when the initial concentration of bacteria was 7.1 × 105 cells/ mL. The product of the biodegradation of BDE-47 was BDE-28. The biodegradation of BDE-47 fit well with first-order kinetics, and its degradation kinetics was ln Ct = - 0.104t + 6.22. With the addition of an electron acceptor, such as Fe3+, SO4 2- and NO3 -, the BDE-47 degradation rate was significantly increased to 49.8%, 59.1%, and 67.3%, respectively. The above results revealed that the strain could degrade BDE-47, which is of importance in the application of environmental bioremediation of BDE-47. © 2018 Science Press. All rights reserved.     

Screening and characterization of extremophiles in spacecraft assembly environment北大核心CSCD

Spacecrafts need to strictly control microorganisms before entering space flight. The Spacecraft Assembly, Integration, and Test Center (AITC) is an important environmental source for spacecrafts to carry microorganisms. The assembly clean room has characteristics of ventilation, dryness, and lack of nutrients that are not conducive to the growth and reproduction of microorganisms, except for extremophiles. In this study, based on the internal air and surface environment of the AITC in China, 13 strains of bacteria were identified by plate culture and 16S sequence analysis, and their extreme environmental tolerance, antibiotic resistance, and film-forming ability were tested. All these bacteria belonged to the Firmicutes and Proteobacteria phyla, and nine strains belonged to the Bacillus genus. All 13 strains of bacteria were salt-tolerant, acid-tolerant, and alkali-tolerant, and 69.2% of the bacteria survived heat shock at 80 ℃. Among these, one strain of Sphingomonas sp. JCM7513 isolated from the surface environment was insensitive to all the tested antibiotics and had strong drug resistance, while the other 12 strains were sensitive to most β-lactam antibiotics but had strong resistance to tetracyclic antibiotics and erythromycin. Most of the isolated bacteria exhibited strong biofilm-forming abilities. The study showed that there are a certain number of extremophiles in the spacecraft assembly environment. To protect spacecrafts from biological corrosion and planetary protection forward pollution, more effective monitoring and elimination methods are needed. © 2022 Science Press. All rights reserved.     

Isolation,identification and desulfurization mechanism of a sulfur-oxidizing bacterium with salt tolerance北大核心CSCD

Micro-organism with efficient desulfurization performance is a key factor in the biological desulfurization technology. This study aimed to seek such a sulfur-oxidizing strain and understand its desulfurization mechanism. Wastewater in a sewage station of natural gas purification plant was used to screen the sulfide-oxidizing strain, and to identify it based on sequence similarity analysis of 16S rDNA and the morphological characteristics. Thiosulfate was used as substrate for investigating the sulfur oxidation performance and salinity tolerance; the OD600, content change of thiosulfate, sulfate, sulfur, pH and total alkalinity in the cultural system were also investigated. The strain DS-B was found to share the highest sequence similarity with Thioalkalivibrio thiocyanoxidans ARh2, therefore determined as Thioalkalivibrio. At the optimum temperature of 35 °C for growth and degradation, the removal efficiency of thiosulfate could reach 98.7% after 7 days. Strain DS-B had strong resistance to thiosulfate, and the optimal concentration of S2O32- was 2 × 104 mg/L. The analysis for sulfur oxides showed that it could oxidize thiosulfate by the pathway of S2O32-→SO42- / S2O32- → S → SO42-. Therefore the strain DS-B is a sulfur-oxidizing bacterium with great application prospect for its strong salt tolerance and conspicuous removal capability for thiosulfate.     

Estimating the removal of atmospheric particulate pollution by the urban tree canopy in Beijing北大核心CSCD

Urban green space, particularly the tree canopy, plays an important role in potential mitigation against atmospheric particulate pollution and protecting human health. In this study, current and future air particulate matter [including total suspended particulate (TSP), particulate matter 10 (PM10), and particulate matter 2.5 (PM2.5)] removal by the urban tree canopy of Beijing was estimated. A modeling approach was used based on the distributed measurement evaluation and a modified version. The urban tree canopy of Beijing, including mostly Platycladus sp., Pinus sp., Quercus sp., Robinia pseudoacacia, and economic forests, currently removes about 8.33 million kg/a air particulates, in which TSP accounted for 4.51 million kg/a, PM10 accounted for 2.74 million kg/a, and PM2.5 accounted for 1.08 million kg/a. The study on the removal of air particulates by different aged tree canopies showed that in coniferous trees, the ability to capture air particulates changed in the order of mature and over-mature > near-mature forest > young forest; in broadleaf forest, the ability changed in the order of near-mature forest > mature and over-mature > young forest. For total particulate matter, the biggest contribution was coarse particulates (60.74%); the contribution rate of fine particulates was different owing to different tree species groups. The results suggested that the ability of different trees to capture particles and age of forests varied widely and that suitable trees should be chosen to enhance pollution mitigation for city greening. © 2018 Science Press. All rights reserved.     

Responses of phytoplankton and periphytic diatoms to environmental factors in a tropical riverine reservoir北大核心CSCD

Riverine reservoirs have a short water retention time, which is ecologically more similar to that of rivers. Generally, phytoplankton-based approaches are used for lakes and periphytic diatom-based approach for rivers. To understand the differences in the responses of phytoplankton and periphytic diatoms to environmental variables for riverine reservoirs, we collected periphytic diatom samples on artificial substrata as well as phytoplankton samples from a tropical reservoir with a resident time less than 10 days. Our results showed that 131 phytoplankton species and 138 periphytic diatoms were detected; the variation of phytoplankton community was mainly reflected by the dominant species with a strong response to the environmental variables at a time scale, whereas the variation of periphytic diatom community was noted in both the species composition and the dominant species, with a strong response at spatial-temporal scales. The multivariate regression analysis and redundancy analysis showed that environmental factors have higher explanations for the variance of the periphytic diatom community (R2 = 0.27). Temperature was the key explanatory variable for phytoplankton, planktonic diatoms and periphytic diatoms (P < 0.01). However, dissolved oxygen and nitrate were also detected as significant explanatory factors associated with periphytic diatom community (P < 0.01). Thus, the periphytic diatoms were concluded to be more sensitive to environmental change and were associated with more environmental variables than phytoplankton. Periphytic diatoms appear to provide more ecological information than phytoplankton for riverine reservoirs. © 2018 Science Press. All rights reserved.     

Spatial evolution and specialization division of crop planting structure in counties of Tibet,China北大核心CSCD

从农业区域系统的角度分析农作物的空间集聚和专业化,可为农业产业结构调整及优化提供决策依据.以西藏粮食作物、油料作物、蔬菜和饲草4类作物为研究对象,基于1995-2020年西藏农业统计年鉴农作物播种面积数据分析西藏农作物种植面积时序变化,基于1995-2018年统计年鉴农作物播种面积数据和74个县域空间单元,综合运用重心模型、基尼系数、区位熵及空间自相关模型,通过ArcGIS软件分析西藏作物种植空间变化及专业化格局.结果显示:(1)西藏粮食作物种植面积占比历年均占绝对优势,但呈逐年下降趋势,油料作物种植面积整体呈波动性小幅上升,蔬菜和青饲料种植面积逐年明显增长.粮食作物、经济作物(含油料作物和蔬菜)、饲料作物比例从1995年的86:12:2调整到2020年的68:17:14.(2)1995-2015年间西藏粮食和油料生产重心较为稳定,未出现较大范围的地理迁移,其他农作物重心迁移距离较大,从东南向西北迁移416.7 km.(3)西藏农作物均呈现一定程度的空间集聚和区域专业化生产格局,但在研究期内生产集聚及专业化水平呈下降趋势.(4)将西藏粮食、油料和其他农作物划分为绝对优势区、比较优势区、优势衰退区、潜力优势区、不具优势区、优势退出区、可种植区和无种植区8种类型.本研究表明西藏农作物种植结构调整明显,基于生产格局及演变趋势划定了专业化分区,可引导农作物生产布局优化,对有效保障西藏地区粮食安全具有重要意义.(图6表5参26)     

Cloning,expression, and functional identification of CaSWEET7 and CaSWEET15 genes in Canarium album北大核心CSCD

糖外排转运蛋白(sugars will eventually be exported transporters,SWEET)介导植物光合同化产物蔗糖的跨膜运输.以橄榄(Canarium album(Lour.)Raeusch.)果实为材料,通过气相色谱串联质谱(GC-MS)检测橄榄果实中糖组分及含量变化,利用RT-PCR技术克隆得到CaSWEET7和CaSWEET15基因开放阅读框(ORF)序列.结果表明:CaSWEET7和CaSWEET15基因ORF全长分别为774 bp和951 bp,分别编码长度为257个和316个氨基酸残基,具有2个MtN3_slv结构域;进化树分析表明,CaSWEET7属于CladeⅡ,CaSWEET15属于CladeⅢ.实时荧光定量PCR(qRT-PCR)技术检测其在不同发育时期的果实中相对表达量变化,结果表明,随着果实发育,CaSWEET7和CaSWEET15表达量逐渐递增,且与果实发育蔗糖含量变化呈显著正相关(相关性系数分别为0.931和0.904,P<0.05);利用酵母功能互补证明CaSWEET7和CaSWEET15基因编码的蛋白具有转运蔗糖能力.本研究表明CaSWEET7和CaSWEET15基因可能在橄榄果实蔗糖积累中发挥作用.(图9表2参44)     

Population dynamics of farmland ladybug resources and dominant species in Nyingchi,Tibet, China北大核心CSCD

捕食性瓢虫是重要的天敌昆虫,有利于害虫的生物防治.为查清西藏林芝地区农田瓢虫资源与种群现状,明确优势种类及种群动态和规律,对林芝不同生态区域的青稞、小麦、油菜3种作物农田开展瓢虫资源调查研究,同时选取固定样地定期进行种群动态分析.结果显示:林芝地区农田瓢虫分为2个亚科4个族10个属,共13种,其中11种为捕食性瓢虫.主要优势瓢虫种类为横斑瓢虫、多异瓢虫、二星瓢虫.其中横斑瓢虫在全部调查样地中均有分布,在农田中总体优势度指数、相对多度为最高.3种优势瓢虫在不同作物中种群动态变化规律存在差异,其中横斑瓢虫虫口密度长期高于其余优势瓢虫,且与蚜虫密度曲线有较为明显的重合现象.横斑瓢虫种群密度峰值主要集中在6月中旬至7月上旬,但在不同作物农田中具体峰值时期存在差异.可见,林芝地区农田不同种类瓢虫之间有较大数量差异,在不同生态区域与作物环境下具有不同的种群特征,但是优势瓢虫种类与种群规律较为明确,可用于农田蚜虫生物防治;结果可为保护当地重要昆虫资源及开展生物防治提供基础数据支撑.(图4表6参23)