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51.
52.
Twenty four plots, each 2.0 m2 in area, were established on St. Augustine loam soil series as field plots and microplots (containing lysimeters) in a completely randomised block design of four treatments (mulched fertilized, unmulched fertilized microplots; mulched fertilized and unmulched fertilized field plots), replicated three times. Labelled (15N) and unlabelled (NH2)2CO fertilizer were applied at rates of 400 kg N ha–1 and CaH2PO4 and KCl were applied at rates of 100 and 150 g ha–1 respectively to the field plots and microplots. Mulch (bagasse) was maintained to a depth of two cm and the plots were kept bare with regular applications of gramoxone.The maximum depth of leaching as measured by diffusion of NO
3
–
–15N in both the dry and wet seasons was 30 cm. The potential for downward movement of water and NO
3
–
–15N was low in the wet season because high intensity rainfall followed high soil moisture contents. Effects of mulching, on the mobility of applied N fertilizers were inconclusive. Infiltration rates were significantly (P=0.25) inversely correlated with soil moisture content, supporting the hypothesis that high intensity rainfall on a saturated soil surface is more likely to result in NO
3
–
–15N dispersion than NO
3
–
–15N leaching. 相似文献
53.
IV Zlatkin M Schneider FJ de Bruijn LJ Forney PhD 《Journal of industrial microbiology & biotechnology》1996,17(3-4):219-227
Culturable bacteria from the deep subsurface (179 m) at Cerro Negro, New Mexico were isolated and characterized. The average number of viable aerobic bacteria was estimated to be 5×105g–1 of sediment, but only about 0.1% of these could be recovered on agar medium when incubated under aerobic conditions. Of 158 strains isolated from this depth, 92 were characterized by cellular fatty acid profiles (FAME), 36 by analysis of partial 16S rDNA sequences, and 44 by rep-PCR genome fingerprint analysis using three different sets of oligonucleotide primers (REP, BOX, or ERIC). These analyses showed the majority of isolates (67%) were Gram-positive bacteria and primarily members of genera with a high %G+C DNA. The remaining isolates were -subdivisionProteobacteria (19%) and members of the flavobacteria group (14%). The diversity indices based on these different methods of characterization were very high suggesting this subsurface habitat harbors a highly diverse microbial community. 相似文献
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The effect of abscisic acid on growth, ultrastructure and nucleic acid biosynthesis was studied in tissue culture of spinach (Spinacia oleracea L.). Low concentration (0.01 mg l?1) of abscisic acid increased fresh and dry weight of calluses, whereas 1.0 mg l?1 was inhibitory. The stimulating effect was observed only in the presence of a relatively high concentration of kinetin (1 mg l?1). The inhibitory effect was partly overcome by the same kinetin concentration. The low concentration of abscisic acid probably accelerated the induction of callus growth after subculture and stimulated cell division in the exponential phase of growth. Electron microscopy showed the presence of numerous polysomes and rough endoplasmic reticulum in callus cells grown at the stimulating abscisic acid concentration. Control cells and cells at the inhibitory concentration had slightly hyaline cytoplasm and were more vacuolated. Incubation of callus tissue with 32P in the presence of stimulating concentration of abscisic acid showed a significant increase in the rate of biosynthesis of all nucleic acid classes after 8 h, whereas inhibitory concentration produced a decrease in 32P incorporation. However, when the tissue was grown in the presence of abscisic acid for 20 days, both concentrations decreased the rate of nucleic acid biosynthesis, as compared to the controls. 相似文献
56.
Changes in ionized calcium were studied in axons isolated from living squid by measuring absorbance of the Ca binding dye Arsenazo III using multiwavelength differential absorption spectroscopy. Absorption changes measured in situ were calibrated in vitro with media of ionic composition similar to axoplasm containing CaEGTA buffers. Calcium loads of 50-2,500 μmol/kg axoplasm were induced by microinjection, by stimulation in 112 mM Ca seawater, or by soaking in choline saline with 1-10 mM Ca. Over this range of calcium loading of intact axoplasm, the ionized calcium in the axoplasm rose about 0.6 nM/μM load. Similar loading in axons preteated with carbonyl cyanide 4- trifluoromethoxyphenylhydrazone (FCCP) to inhibit the mitochondrial proton gradient increased ionized calcium by 5-7 percent of the imposed load, i.e. 93-95 percent of the calcium load was buffered by a process insensitive to FCCP. This FCCP- insensitive buffer system was not saturated by the largest calcium loads imposed, indicating a capacity of at least several millimolar. Treatment of previously loaded axons with FCCP or apyrase plus cyanide produced rises in ionized calcium which could be correlated with the extent of the load. Analysis of results indicated that, whereas only 6 percent of the endogenous calcium in fresh axons is stored in the FCCP-sensitive (presumably mitochondrial) buffer system, about 30 percent of an imposed exogenous load in the range of 50-2,500 μM is taken up by this system. 相似文献
57.
为建立鸭乙型肝炎病毒LJ-76的转染细胞系,将LJ-76病毒DNA插入到pUC19的EcoRⅠ位点上,分离得到含有双拷贝LJ-76DNA的重组质粒.通过磷酸钙沉淀方法,将经CsCl等密度离心纯化的LJ-76DNA双体导入到人肝癌细胞BEL7402中.收集转染细胞的培养液进行蔗糖密度梯度离心,所得沉淀经检测发现含有LJ-76DNA并具有特异性DHBV内源性DNA多聚酶活性;对上述样品通过DotEIA检测DHBV核心抗原及表面抗原结果为阳性.Southernblot分析表明转染细胞内存在病毒DNA复制中间体cccDNA、ssDNA和rcDNA,而cccDNA被认为是复制活动较为活跃的标志.电镜观察转染细胞的上清发现有病毒颗粒的存在. 相似文献
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Danyel GJ Jennen Addie LJ Vereijken Henk Bovenhuis Richard MPA Crooijmans Jan J van der Poel Martien AM Groenen 《遗传、选种与进化》2005,37(3):215-228
In this report we describe the analysis of an advanced intercross line (AIL) to confirm the quantitative trait locus (QTL) regions found for fatness traits in a previous study. QTL analysis was performed on chromosomes 1, 3, 4, 15, 18, and 27. The AIL was created by random intercrossing in each generation from generation 2 (G2) onwards until generation 9 (G9) was reached. QTL for abdominal fat weight (AFW) and/or percentage abdominal fat (AF%) on chromosomes 1, 3 and 27 were confirmed in the G9 population. In addition, evidence for QTL for body weight at the age of 5 (BW5) and 7 (BW7) weeks and for the percentage of intramuscular fat (IF%) were found on chromosomes 1, 3, 15, and 27. Significant evidence for QTL was detected on chromosome 1 for BW5 and BW7. Suggestive evidence was found on chromosome 1 for AFW, AF% and IF%, on chromosome 15 for BW5, and on chromosome 27 for AF% and IF%. Furthermore, evidence on the chromosome-wise level was found on chromosome 3 for AFW, AF%, and BW7 and on chromosome 27 for BW5. For chromosomes 4 and 18, test statistics did not exceed the significance threshold. 相似文献
60.