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For revealing the degradation effect of acid-alcohol modification on starch, commercial corn and potato starches were hydrolyzed by 0.36% HCl in methanol at 25°C for 1 to 15 days. Results showed the yields of the modified starches ranged from 91 to 100%, and the average granule size of the modified starch was slightly smaller as compared to their counterpart native starches. After 15 days of modification, no significant configuration change was found whereas the solubility of starches obviously increased with the increase in the hydrolysis time. Corn starch showed a slower increasing tendency than that of potato starch. Gelatinization onset temperatures (To) of starches after modification showed a decrease tendency in corn starch, and an increase tendency in potato starch. For both corn and potato starches, the peak (Tp) and conclusion (Tc) temperatures of gelatinization increased with the increase in the treatment time. Consequently, the range of gelatinization increased from 12.2 to 23.9°C for corn starch, and from 12.8 to 19.8°C for potato starch. However, the gelatinization enthalpies ( • H) of modified starches showed 1 to 2 J/g lower than their counterpart native starches. For the acid-alcohol treated starches, the area of amylopectin fractions determined by high-performance size exclusion chromatography (HPSEC) decreased with the treatment time. Compared to the gradual degradation pattern of corn starch, potato starch showed a stepwise pattern. The weight average degree of polymerization (DPW) of starches rapidly decreased within the first 5 days of treatment, and potato starch had a higher rate of decrease than corn starch. The number average degree of polymerization (DPn) of corn and potato starches after acid-alcohol treated for 15 days were 162 and 183, respectively. It was concluded that the degradation of amylopectin by the acid-alcohol modification might alter the molecular structure of starch, which resulted in the fast disruption of granule and the decrease of viscosity of starch paste during heating.
Homeodomain-leucine zipper (HD-Zip) transcription factor genes are unique in the plant kingdom. Studies have shown that HD-Zip transcription factor has four subfamilies (subfamilies I–IV), and each subfamily exerts similar or diverse functions in the growth and development as well as environmental stress responses of plants. Although a genome-wide analysis of this transcription factor has been performed in some species, systematic identification of sequences and expression patterns under biotic and abiotic stress have not been carried out in pear. In this study, we identified 52 putative HD-Zip genes within the pear genome. Based on the phylogenetic analysis, HD-Zip transcription factors were classified into four subfamilies: 18, 13, 5, and 16 members were identified separately in subfamilies I, II, III, and IV, respectively. Genes in the same subfamily shared the constituent structure and conserved motifs, thereby implying that the HDZip genes that shared similar structures may exert similar functions. Moreover, abundant stress-related and pathogenrelated cis-elements were observed in the promoter region of the pear HD-Zip I and II genes. Transcript abundance level of 20 selected HD-Zip I and II genes were analyzed by quantitative real-time RT-PCR (qRT-PCR) during the infection of Alternaria alternata, and abiotic stress conditions such as drought and salinity treatment. The results confirmed that some genes display stress-inducible and pathogen-inducible expression patterns.
The air pollution index (API) and meteorological parameters in four cities (Harbin, Changchun, Shenyang, and Dalian) in north-eastern China were analyzed in 2001-12, to study the characterization of the API and its influential factors. According to the monitoring data, air pollution is a significant problem in northeastern China, with all four industrial cities heavily polluted, especially Shenyang. During the study period, the API in the cities was down slightly. Clear interannual, seasonal, and monthly variations of air pollution were determined, which indicated that air quality was poorest in winter (especially November and December), but improved in summer (especially July and August). Air quality level varied in different weather conditions. Water vapor pressure was the most influential meteorological factor with regard to the API, followed by air temperature and surface pressure. Wind direction was found to be an important influential factor with regard to air pollution, because air flow from different directions has an impact on the accumulating or cleaning process of pollutants. However, the dominant meteorological factors influencing air pollution varied in each of the cities in terms of season, time scale, and level of air pollution. Our results highlight the significant impact of synoptic weather on API in northeastern China.
Artemisia annua L. is the main source of artemisinin, currently the most effective treatment for malaria. However, an affordable and abundant supply of artemisinin remains elusive. Trichoderma is a biocontrol agent that stimulates plant growth and defense responses, and improves soil quality. To date, relatively few studies have focused on improving leaf biomass and artemisinin production in A. annua using Trichoderma. To investigate the role of T. asperellum ACCC30536 in improving the artemisinin yield of A. annua, field-grown A. annua was inoculated with T. asperellum conidia and grown for 60 days. The results showed that leaf artemisinin concentration and dry weight were increased significantly after inoculation. The optimal inoculation dose was 200 mL of conidia suspension at 1 × 10⁷ colony-forming units (cfu)/mL, the highest artemisinin concentration was 8.83 mg/g, and the highest artemisinin production was 70.6 g on day 50. The results of qRT-PCR revealed that expression of genes encoding key enzymes for artemisinin biosynthesis, namely HMGR1, FPS, ADS, CYP71AV1, CPR, DBR, DXS1, and DXR1, was generally upregulated during days 20–50 following induction by Trichoderma. In addition, the moisture, pH stability, organic matter content, and availability of nitrogen, phosphorus, and kalium in inoculated soil were significantly improved. Thus, application of T. asperellum ACCC30536 may offer a novel approach for improving artemisinin production by upregulating the expression of key enzymes for artemisinin biosynthesis, increasing leaf yield, and improving soil fertility.
RT-qPCR is a widely used method in gene expression and transcriptome studies. Normalization based on reference genes is necessary to accurately analyze RtqPCR data. Thus, an accurate and systematic evaluation of these reference genes before experiments are conducted is necessary. In this study, 18 candidate reference genes were evaluated under various experimental conditions covering a range of tissue types and cultivars, NaCl, CaCl2 and temperature treatments, hormones (6-BA, ABA and NAA) and a set of osmotic stress (mannitol and PEG6000) treatments. Gene expression across 48 pear samples was evaluated using geNorm, NormFinder and BestKeeper statistical algorithms. Actin2/7 (ACT2/7), ubiquitin extension protein (UBI) and Yellow-leaf-specific gene 8 (YLS8) exhibited the most stable expression across all the pear samples tested. While in the other experimental groups, different sets of samples had their own best reference genes. In addition, the gene expression of PbCBL7, a member of the calcineurin B-like protein, was measured across all the 48 samples using the best three reference genes, it displayed variation in gene expression across different tissues and cultivars, and exhibited diverse up- or down-regulated expression patterns under various treatments, which indicate that PbCBL7 may play a role in response to specific abiotic stress in pear. These results are valuable for future research on gene expression and abiotic stress tolerance in pear.
Community surveys were performed in 30 forest stands with similar conditions under different management types in forests of northeastern China to study the influence of forest management on plant biodiversity. We evaluated this effect by calculating and analyzing species richness, vegetation structure, and aboveground biomass. Large variations in species composition, vegetation structure, species richness, and aboveground biomass were evident among the three types of common management types investigated (cut shrub tending, selective cutting, and understory planting). The species composition of the herb layer changed more than that of the shrub layer, and herbs were more vulnerable to impact from human activities. Each management type reduced the plant coverage, and this was most significant in planted plots. We found that in the cut shrub tending plots, the shrub height increased over time. The mean fresh weight of the control group was about 2 kg·m-2, which was about two-fold the selective cutting group (1 kg·m-2) and five-fold the understory planting group (0.4 kg·m-2). Our results also showed that management types in mixed forest stands strongly impact species diversity and, to some extent, environmental capacity, with negative effects on biodiversity.
We used the “space for time substitution” method to test the effects of reclamation history on evolution processes of soil properties and heavy metal concentrations. A total of 129 surface soil samples were collected in a reclamation zone of the Liaohe River Delta, which was divided into three reclaimed zones (1930s, 1960s, and 1990s), marsh, and intertidal flats. Soil metals (Fe, Mn, Cd, Cr, Cu, Ni, Pb, and Zn), soil particle size, pH, salinity, soil organic carbon (SOC), nitrate nitrogen (NO₃⁻-N), and available phosphorus (AP) were analyzed. Results obtained from correlation analysis and factor analysis showed that there were significant positive correlations (p<0.01) between the fine particle fractions (clay and silt) and metal concentrations. Using ANOVA, we found that soil erosion and leaching desalination had significant effects on the distributions of soil properties and heavy metal contents in short-term reclamation (1990s zone), and that sustained human activities have played an important role in long-term reclamation (1960s zone). Results of the enrichment factor (EF) and inverse distance weighting (IDW) indicated that Cd pollution had reached high pollution levels, followed by Cr pollution. Taking necessary measures is significant for sustainable utilization and management of coastal resources.
In order to investigate whether PCV2b can be transmitted across the placenta in sows thereby causing vertical infection of fetuses, six sows in 75 day of pregnancy were either intramuscularly inoculated with a PCV2b culture supernatant (n = 4) or mock infected with cell culture supernatant (n = 2). At parturition, 3 newborn piglets from each litter were randomly selected and euthanatized prior to suckling. Samples of the mesenteric lymph nodes, spleens, kidneys, hearts and lungs were collected for PCR, histopathological and immunohistochemical assays. The results showed that the newborn piglets from PCV2b-infected sows had histopathological lesions in the tested tissues. Moreover, PCV2b antigen and DNA were detected as well. These findings therefore suggested that porcine circovirus type 2b can be transmitted across the placenta of sows, thereby leading to PCV2b vertical infection of the fetuses.
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