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1.
Dr. Ed. Formánek 《Plant Systematics and Evolution》1888,38(12):419-423
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Dr. Ed. Formánek 《Plant Systematics and Evolution》1888,38(6):186-190
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Dr. Ed. Formánek 《Plant Systematics and Evolution》1884,34(5):157-168
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Ed Echeverria 《Physiologia plantarum》1991,81(1):51-54
The sucrose content of acid lime [ Citrus aurantifolia (Christm.) Swing.] juice tissue was measured at time 0 and at various times following incubation at 15.5, 26.6 and 37.7°C. The decline in sucrose content in fruit stored at 15.5°C paralleled the expected values for a sucrose solution at pH 2.1. At higher temperatures, the in vivo sucrose content decreased at significantly lower rates than the expected values. In fruit stored at 26.6 and 37.7°C, the vacuolar pH increased 0.11 and 0.23 units, respectively. When sucrose hydrolysis was recalculated at the increased vacuolar pH of juice cells stored at 26.6 and 37.7°C, the calculated values were similar to the measured values obtained in vivo. It is concluded that within the limits of the experimental conditions, the rates of sucrose acid hydrolysis are regulated by changes in the vacuolar H+ concentration. 相似文献
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Transient expression of the proto-oncogene int-1 during differentiation of P19 embryonal carcinoma cells. 总被引:6,自引:2,他引:4 下载免费PDF全文
In mouse embryos, the int-1 proto-oncogene is transiently expressed in areas of the developing neural system. Retinoic acid-treated P19 embryonal carcinoma cells have often been used as an in vitro model for the molecular basis of neural development. We shown here that int-1 is transiently expressed in differentiated P19 cells. The time course and retinoic acid dose dependence of int-1 expression suggest that the gene is specifically expressed during early neural differentiation. P19 cells may be a useful model to assist in the study, at the cellular level, of the role of int-1 in neural development. 相似文献
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PRODUCTION AND CHARACTERIZATION OF MULTIPLE-LAYERED POPULATIONS OF ANIMAL CELLS 总被引:11,自引:5,他引:6 下载免费PDF全文
Dense populations containing 129 x 106 Jensen sarcoma, 134 x 106 DON Chinese hamster, 28.9 x 106 WI-38 human diploid, 61.8 x 106 HEp-2 human carcinoma, and 67.4 x 106 WISH human amnion cells were produced from dilute inocula, 0.85 to 5.33 x 106, in 7 to 8 days in a perfusion system using replicate T-60 flasks. Perfusion rates as high as 560 ml medium/day/T-60 were required to maintain pH (to ca ±0.1 unit) and adequate nutrient supplies. The cell densities encountered are described by the term "monolayer equivalents" (M.E.), defined as number of cells per culture divided by number of cells in a monolayer. The M.E.'s for T-60 cultures containing unusually dense populations of 40 x 106 WI-38 and 250 x 106 DON cells (9-day perfusion) were 5 and 17, respectively, and numbers of cells in illustrations of stained cross-sections of membranes from these cultures were in excellent agreement. Threshold M.E.'s exist below which proliferation is the chief cellular activity and above which one or more cell functions may predominate even though proliferation persists. Cellular nutrition and metabolism may change with changes in M.E., as illustrated in different patterns of glutamic acid, proline, and glycine utilization or production in dense vs. dilute WI-38 cell populations. The results indicated that the role of contact inhibition phenomena in arresting cellular proliferation was diminished in perfusion system environments. 相似文献
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