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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
Ohne Zusammenfassung 相似文献
5.
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
6.
J. Stover 《Zoo biology》1987,6(3):265-271
Examination of the reproductive anatomy of six female white-tailed gnu revealed duplex uterus with varying degrees of cervical division. The division ranged from 36 to 100% of the length of the cervix, with one animal exhibiting double external ossa. This variability in reproductive anatomy could be important in artificial insemination or embryo transfer procedures in this species. 相似文献
7.
Interactions of the receptor for insulin-like growth factor II with mannose-6-phosphate and antibodies to the mannose-6-phosphate receptor 总被引:4,自引:0,他引:4
R A Roth C Stover J Hari D O Morgan M C Smith V Sara V A Fried 《Biochemical and biophysical research communications》1987,149(2):600-606
Recently, the sequence of the human receptor for insulin-like growth factor II (IGF-II) was found to be 80% identical [Morgan et al., (1987) Nature 329, 301-307] to the sequence of a partial clone of the bovine cation-independent mannose-6-phosphate receptor [Lobel et al., (1987) Proc. Natl. Acad. Sci. USA 84, 2233-2237]. In the present study, the purified receptor for insulin-like growth factor II (IGF-II) was found to react with two different polyclonal antibodies to the purified mannose-6-phosphate receptor. Moreover, mannose-6-phosphate was found to stimulate the binding of labeled IGF-II to the IGF-II receptor by two-fold. This effect had the same specificity and affinity as the reported binding of mannose-6-phosphate to its receptor; mannose-1-phosphate and mannose had no effect on the binding of labeled IGF-II to its receptor, and the half-maximally effective concentration of mannose-6-phosphate was 0.3 mM. Also, mannose-6-phosphate did not affect labeled IGF-II binding to the insulin receptor. These results support the hypothesis that a single protein of Mr-250,000 binds both IGF-II and mannose-6-phosphate. Furthermore, they indicate that mannose-6-phosphate can modulate the interaction of IGF-II to its receptor. 相似文献
8.
Expression and characterization of a functional human insulin-like growth factor I receptor 总被引:20,自引:0,他引:20
G Steele-Perkins J Turner J C Edman J Hari S B Pierce C Stover W J Rutter R A Roth 《The Journal of biological chemistry》1988,263(23):11486-11492
Stable transfectants of Chinese hamster ovary (CHO) cells were developed that expressed the protein encoded by a human insulin-like growth factor I (IGF-I) receptor cDNA. The transfected cells expressed approximately 25,000 high affinity receptors for IGF-I (apparent Kd of 1.5 X 10(-9) M), whereas the parental CHO cells expressed only 5,000 receptors per cell (apparent Kd of 1.3 X 10(-9) M). A monoclonal antibody specific for the human IGF-I receptor inhibited IGF-I binding to the expressed receptor and immunoprecipitated polypeptides of apparent Mr values approximately 135,000 and 95,000 from metabolically labeled lysates of the transfected cells but not control cells. The expressed receptor was also capable of binding IGF-II with high affinity (Kd approximately 3 nM) and weakly recognized insulin (with about 1% the potency of IGF-I). The human IGF-I receptor expressed in these cells was capable of IGF-I-stimulated autophosphorylation and phosphorylation of endogenous substrates in the intact cell. This receptor also mediated IGF-I-stimulated glucose uptake, glycogen synthesis, and DNA synthesis. The extent of these responses was comparable to the stimulation by insulin of the same biological responses in CHO cells expressing the human insulin receptor. These results indicate that the isolated cDNA encodes a functional IGF-I receptor and that there are no inherent differences in the abilities of the insulin and IGF-I receptors to mediate rapid and long term biological responses when expressed in the same cell type. The high affinity of this receptor for IGF-II also suggests that it may be important in mediating biological responses to IGF-II as well as IGF-I. 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