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11.
Human lung tumor sensitivity to difluoromethylornithine as related to ornithine decarboxylase messenger RNA levels 总被引:2,自引:0,他引:2
R A Casero S B Baylin B D Nelkin G D Luk 《Biochemical and biophysical research communications》1986,134(2):572-579
The differential response to polyamine depletion has been studied in two types of human lung tumor cells. Small cell lung carcinoma cells die following polyamine depletion by difluoromethylornithine treatment while non-small cell lines demonstrate a typical cytostatic response. We now report that a small cell line, NCI H82, has a lower apparent capacity for polyamine biosynthesis than does a representative non-small cell, NCI H157. In subconfluent cultures, the ornithine decarboxylase activity is 25 times lower in the small cell than the non-small cell and by comparison, the polyamines in the small cell line are markedly reduced. Most significantly, levels of mRNA coding for ornithine decarboxylase are approximately 100-fold lower in the small cell than the non-small cell line, and this difference does not appear to be a result of gene rearrangement. These results suggest that differential sensitivity to polyamine depletion is related to different steady-state levels of ornithine decarboxylase mRNA. 相似文献
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低温对植物叶片中超氧物歧化酶、过氧化氢酶和过氧化氢水平的影响 总被引:10,自引:0,他引:10
番茄和鸡蛋果叶片中可提取的SOD活性不受低温的影响。在电泳谱带上SOD主同工酶带被氰化物而不被低温抑制,次同工酶带在低温下不稳定,且活性很低,它的变化不影响总的SOD活性。一些冷敏感植物叶片中CAT活性被低温抑制,而H_2O_3水平在低温下稳定或有增加,这可能使毒性更强的羟基离子(OH·)易于形成。 相似文献
15.
Wingfield BD; Grant WS; Wolfaardt JF; Wingfield MJ 《Molecular biology and evolution》1994,11(3):376-383
The genus Ceratocystis sensu stricto includes important fungal pathogens of
woody and herbaceous plants. This genus is distinguished from species in
Ceratocystis sensu lato by the presence of Chalara anamorphs. Ascospore
shape has been used extensively in delineating Ceratocystis taxa, which
show a large variety of ascospore shapes. Sequence analysis of one region
of he 18S ribosomal RNA subunit and two regions of the 28S ribosomal RNA
subunit showed that there was a majority of multiple substitutions at
nucleotide sites and that there was a low transition/transversion ratio, T
= 0.72. Both of these results suggest that these are well established, old
species. Ascospore morphology, for the most part, was not congruent with
the molecular phylogeny, and the use of morphological characters may be
misleading in the taxonomy of these species.
相似文献
16.
BD Llewellyn 《Biotechnic & histochemistry》2013,88(4):159-177
The hematoxylin and eosin stain is the most common method used in anatomic pathology, yet it is a method about which technologists ask numerous questions. Hematoxylin is a natural dye obtained from a tree originally found in Central America, and is easily converted into the dye hematein. This dye forms coordination compounds with mordant metals, such as aluminum, and the resulting lake attaches to cell nuclei. Regressive formulations contain a higher concentration of dye than progressive formulations and may also contain a lower concentration of mordant. The presence of an acid increases the life of the solution and in progressive solutions may also affect selectivity of staining. An appendix lists more than 60 hemalum formulations and the ratio of dye to mordant for each. 相似文献
17.
Park JI Powers JF Tischler AS Strock CJ Ball DW Nelkin BD 《Experimental cell research》2005,303(1):79-88
Glial cell line-derived neurotrophic factor (GDNF) can induce neuron-like differentiation of mouse pheochromocytoma (MPC) cell lines derived from mice with a heterozygous knockout mutation of nf1, the murine counterpart of the human gene mutated in neurofibromatosis type 1 (NF1). Here, we show that GDNF-induced differentiation in the MPC 862L cell line is mediated by the MEK/extracellular signal-regulated kinase (ERK) pathway. Neurite outgrowth, increased expression of growth-associated protein 43, and decreased incorporation of bromodeoxyuridine (BrdU) were induced by treatment with GDNF, H-RasV12, or a constitutively active MEK2. GDNF also induces leukemia inhibitory factor (LIF) via the MEK/ERK pathway, and LIF itself can elicit these differentiative changes via a cell-extrinsic autocrine/paracrine pathway. Treatment with anti-LIF neutralizing antibody depleted the differentiative activity of the conditioned medium from cells stimulated for MEK/ERK signaling, while recombinant LIF could induce differentiation in MPC cells, indicating that LIF is the sole factor with differentiative activity. LIF could activate MEK1/2 and STAT3, but LIF-induced differentiation was blocked only by the MEK1/2-specific inhibitor U0126, indicating that the MEK/ERK pathway is necessary for LIF action in MPC cells. Our findings suggest that LIF may be utilized for signaling mediated by GDNF and may be important in the pathobiology of neuroendocrine tumors. 相似文献
18.
Interleukin-1beta (IL-1beta) is a pleiotropic cytokine that can induce several cellular signal transduction pathways. Here, we show that IL-1beta can induce cell cycle arrest and differentiation in the human medullary thyroid carcinoma (MTC) cell line, TT. IL-1beta induces cell cycle arrest accompanied by morphological changes and expression of the neuroendocrine marker calcitonin. These changes are blocked by the MEK1/2 specific inhibitor U0126, indicating that MEK1/2 is essential for IL-1beta signaling in TT cells. IL-1beta induces expression of leukemia inhibitory factor (LIF) and activation of STAT3 via the MEK/ERK pathway. This activation of STAT3 could be abrogated by treatment with anti-LIF neutralizing antibody or anti-gp130 blocking antibody, indicating that induction of LIF expression is sufficient and essential for STAT3 activation by IL-1beta. In addition to activation of the LIF/JAK/STAT pathway, IL-1beta also induced an MEK/ERK-mediated intracellular cell-autonomous signaling pathway that is independently sufficient for growth arrest and differentiation. Thus, IL-1beta activates the MEK/ERK pathway to induce growth arrest and differentiation in MTC cells via dual independent signaling mechanisms, the cell-extrinsic LIF/JAK/STAT pathway, and the cell-intrinsic autonomous signaling pathway. 相似文献
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Sabina I. Robinson Barry Nelkin Scott Kaufmann Bert Vogelstein 《Experimental cell research》1981,133(2)
A detergent insoluble 58 000 D polypeptide is phosphorylated at an increased rate during mitotic arrest in cultured Chinese hamster ovary cells. Using one-dimensional peptide mapping, this polypeptide was identified as a phosphorylated form of intermediate filament protein (IFP). The increased rate of phosphorylation is observed with either colcemid- or vinblastine-treated mitotic cells, but is not seen with similarly treated interphase cells. 相似文献