الملخص
In order to reveal the mechanism of silicon (Si) fertilizer in improving nitrogen (N) and phosphorus (P) nutrient availability in paddy soil, we designed a series of soil culture experiments by combining application of varying Si fertilizer concentrations with fixed N and P fertilizer concentrations. Following the recommendations of fertilizer manufacturers and local farmers, we applied Si in concentrations of 0, 5.2, 10.4, 15.6, and 20.8 μg/kg. At each concentration of added Si, the availability of soil N and P nutrients, soil microbial activity, numbers of ammonia-oxidizing bacteria and P-decomposing bacteria which means that the organic P is decomposed into inorganic nutrients which can be absorbed and utilized by plants, and urease and phosphatase activity first increased, and then decreased, as Si was added to the soil. These indicators reached their highest levels with a Si application rate of 15.6 μg/kg, showing values respectively 19.78%, 105.09%, 8.34%, 73.12%, 130.36%, 28.12%, and 20.15% higher than those of the controls. Appropriate Si application (10.4 to 15.6 µg/kg) could significantly increase the richness of the soil microbial community involved in cycling of N and P nutrients in the soil. When the Si application rate was 15.6 μg/kg, parameters for characterizing microbial abundance such as sequence numbers, operational taxonomic unit (OTU) number, and correlation indices of microbial community richness such as Chao1 index, the adaptive coherence estimator (ACE) index, Shannon index, and Simpson index all reached maximum values, with amounts increased by 14.46%, 10.01%, 23.80%, 30.54%, 0.18%, and 2.64%, respectively, compared with the control group. There is also a good correlation between N and P mineralization and addition of Si fertilizer. The correlation coefficients between the ratio of available P/total P (AP/TP) and the number of ammonia-oxidizing bacteria, AP/TP and acid phosphatase activity (AcPA), AP/TP and the Shannon index, the ratio of available N/total amount of N (AN/TN) and the number of ammoniated bacteria, and AN/TN and AcPA were 0.9290, 0.9508, 0.9202, 0.9140, and 0.9366, respectively. In summary, these results revealed that enhancement of soil microbial community structure diversity and soil microbial activity by appropriate application of Si is the key ecological mechanism by which application of Si fertilizer improves N and P nutrient availability.
الملخص
Aim To study gyrA and parC mutations of clinical Pseudomonas aeruginosa strains. Methods MIC values of 55 clinical P.aeruginosa isolates were determined by agar dilution test and 1 sensitive strain and 8 resistant strains were selected with standard sensitive strain ATCC27853 as control, the quinolone determining region (QRDR) of the gyrA and parC genes were amplified by PCR, the lengths of PCR products were 351 bp and 397 bp. The gyrA PCR products(351 bp) were digested with enzyme sacⅡ. The gyrA and parC gene were sequenced. Results In this study, gyrA genes of all resistant strains had an ACC to ATC mutation in codon 83, leading to the amino acid substitution of an isoleucine for a threonine, and three high level resistant strains also showed a GAC to GGC mutation in codon 87, leading to the substitution of a glycine for an aspartic acid. In addition, four resistant strains also had an TCG to TTG mutation in codon 87 of parC gene, leading to the amino acid substitution of a serine for a leucine. The strains with both gyrA and parC mutations were two to sixteen times more resistant than the strains which had only gyrA mutations. At the same time, a silent mutation (CAC to CAT) in codon 132 of gyrA gene and a silent mutation(GCT to GCG) in codon 115 of parC gene occured, which did not lead to amino acid change. Conclusion The mutations of 83 and 87 codons of gyrA and the mutatations of 87 codon of parC gene were related to fluroquinolone resistance, and the mutations of the 83 codon of gyrA gene were more important.
الملخص
Objective To investigate the localization and distribution of the five endocrine cells in the digestive tract mucosa of ricefield eel(Monopterus albus). Methods Using immunocytochemical technique of strept avidin-biotin-peroxidase complex(SABC) were used. Results At least 5 kinds of immunoreactive endocrine cells distributed in the digestive tract mucosa of M.albus. They were gastrin(Gas),somatostatin(Som),5-hydroxytryptamine(5-HT),insulin(Ins),and neurofilament (NF) immunoreactive endocrine(IRE) cells.Gas and Som-IRE cells distributed between stratified squamous epithelium and goblet cell in esophagus. A large number of Gas-IRE cells were found between gastric fundus epithelium and gastric glands, and only a few in the carcia. Ins, 5-HT and NF-IRE cells distributed in the epithelium pylorus and pyloric glandular tube respectively. No any immunoreactive positive reaction was found in the gut of M.albus.In addition, immunoreactive positive reaction of glucagons was not found in whole digestive tract.All immunoreactive endocrine cells were dark brown in color.Their morphology was irregular, cytoplasmic process was shorter and thicker, their nucleus showed an empty bubble.They distributed between esophageal epithelium and gastric epithelium or glandular epithelium, and cytoplasmic process extended to the gastric lumen and glandular cavity.Conclusion There is a complex endocrine function of the digestive system in ricefield eel (M.albus) at the lowest vertebrate.
الملخص
Objective To study the relationship between obesity and diabetic retinopathy (DR) in type 2 diabetes mellitus patients.Methods Seventy-two cases of type 2 diabetes mellitus patients were selectively divided into obesity group and non-obesity group according to BMI,obesity group were subdivided into A group(visceral type) and B group(subcutaneous type) according to waist-buttock girth ratio,the prevalance and severity of DR in two group were compared.Results DR in obesity group were significantly higher than those in non-obesity group,there were higher incidence of proliferative DR in obesity group,therefore,incidence of DR in A group was obviously higher than that in B group.Conclusions Obesity is one of the important factors to aggravate the DR in type 2 diabetes mellitus.
الملخص
The pharmacokinetic study of Rifapentine by daily oral administration for 10d and followed by twice weekly for another 3 weeks in 9 volunteers and in comparism with Rifandin were reported. The results showed that the absorption and excretion of Rifapentine were markedly slower than that of Rifandin, its T1/2 was 15h. The Peak plasma level and T1/2 decreased after repeated administration of the drug. This suggested that Rifapentine and Rifandin in similar to Ri-fampin were hepatic microsomal enzyme inducers.