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181.
182.
The neuroblastoma x glioma NG108-15 hybrid cell line, a widely used model for the study of neuronal differentiation, contains a variety of gangliosides including GM1 and its sialosylated derivative, GD1a. To investigate the role of these a-series gangliotetraose gangliosides in neuritogenesis, we have obtained a mutated subclone of NG108-15 that is deficient in that family of gangliosides. NG108-15 cells were grown in the presence of cholera toxin, which killed the large majority of cells, and from the cholera-resistant survivors we isolated a clone, NG-CR72, that lacks GM1 and GD1a in the plasma and nuclear membranes. GM2 concentration was significantly higher in the plasma membrane. Enzyme assay indicated deficiency of UDP-Gal:GM2 galactosyltransferase (GM1 synthase), which was confirmed by incorporation studies with [3H]sphingosine. These cells resembled wild-type NG108-15 in extending dendritic processes in response to dendritogenic agents (retinoic acid, dibutyryl cAMP) but responded aberrantly to axonogenic stimuli (KCl, ionomycin) by extending unstable neurites that showed the cytoskeletal staining characteristic of dendrites. Moreover, mutant cells treated with the Ca2+ elevating axonogenic agents underwent apoptosis over time, attributed to dysfunction of Ca2+ regulatory mechanisms normally mediated by GM1. Such agents caused dramatic and sustained elevation of intracellular Ca2+ in mutant cells, in contrast to modest and temporary elevation in wild-type cells. Exogenous GM1, inserted into the plasma membrane, had no discernable protective effect on NG-CR72 cells whereas LIGA-20, a membrane-permeant derivative of GM1 that entered both plasma and nuclear membranes, blocked apoptosis, permitted extension of stable neurites, and attenuated the abnormal elevation of intracellular Ca2+. 相似文献
183.
Physiological basis of reduced Al tolerance in ditelosomic lines of Chinese Spring wheat 总被引:13,自引:0,他引:13
Aluminum tolerance was assessed in the moderately Al-tolerant wheat (Triticum aestivum L.) cultivar Chinese Spring and a set of ditelosomic lines derived from Chinese Spring. Three ditelosomic lines lacking chromosome
arms 4DL, 5AS and 7AS, respectively, exhibited decreased Al tolerance relative to the euploid parent Chinese Spring based
on reduced root growth in Al-containing solutions. The physiological basis of the reduced Al tolerance was investigated. Measurements
by inductively coupled argon plasma mass spectroscopy of root apical Al accumulation demonstrated that two of these three
lines had a decreased ability to exclude Al from the root apex, the site of Al phytotoxicity. As Al-induced malate exudation
has been suggested to be an important physiological mechanism of Al tolerance in wheat, this parameter was quantified and
malate exudation was shown to be smaller in all three deletion lines compared with Chinese Spring. These results suggest that
the decreased Al tolerance in at least two of the three ditelosomic lines is due to the loss of different genes independently
influencing a single Al-tolerance mechanism, rather than to the loss of genes encoding alternative Al-tolerance mechanisms.
Received: 3 July 2000 / Accepted: 9 August 2000 相似文献
184.
DNA content analysis of insect cell lines by flow cytometry 总被引:1,自引:0,他引:1
The DNA content of insect cell lines (6 lepidoptera, 1 coleoptera and 1 diptera) was determined by flow cytometry. The DNA
profiles of the 8 cell lines tested were different. They were characterized by the presence of several peaks (2 to 7) corresponding
to different ploidy levels, by differences in the fluorescence intensity of each peak and by the proportion of cells in each
peak. Two cell lines (Cf124 and BmN) were constituted of 2 distinct populations of cells. The DNA profiles of the cell lines
were stable among the passages and during the length of time culture. This technique was demonstrated to be useful for the
detection of mixed cell lines and nucleopolyhedrovirus cell infection, using Autographa californica MNPV. The flow cytometry
gives interesting results on the cell cycle and the ploidy level; it appears as a good tool for insect cell lines characterization.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
185.
Masuda T Ohmi K Yamaguchi H Hasegawa K Sugiyama T Matsuda Y Iino M Nonomura Y 《Molecular and cellular biochemistry》1999,190(1-2):99-104
Recently we have established an aortic smooth muscle cell line, p53LMAC01 obtained from p53 knockout mice. This cell line showed some differentiated properties which were accelerated by 5-azacytidine treatment [1]. In this study, further characterization of p53LMAC01 cell line was investigated according to cell growth and differentiation, and especially focused into the changes of cell feature, actin filaments' formation, and changes of intracellular calcium concentrations to sympathetic nerve transmitter, norepinephrine. While the cell feature was changed from flattened shape to extended form during 4 days, actin filaments were developing, arranging in parallel to longitudinal direction, and gathering under the surface membrane. In 11 days many cells died and detached from substrate, while actin filaments became poor except for the surface membrane in the remained cells. Appearance of calcium response to noradrenalin needed several days after passage as well as a morphological change of the cells for the extended form and development of actin filaments. The calcium response was maintained on 11 days, which coincided with the result that the cells hold actin filaments under the surface membrane. These results suggest that p53LMAC01 cell line maintains several differentiated characters of adult smooth muscle cell and that their expression needs several days after passage. 相似文献
186.
We report here the cloning and tissue distribution of the human B3GALT7 gene, a member of the beta1,3-Glycosyltransferase family, structurally related to the beta1,3-Galactosyltransferase family and beta1,3- N -acetylglucosaminyltransferase family, isolated from a human lung cDNA library. B3GALT7 is mapped to chromosome 19q13.2 by browsing the UCSC genomic database. It contains an ORF with length of 1191bp, encoding a protein with a signal peptide sequence and galactosyl-T domain, and its molecular weight and isoelectric point is predicted to be 43.3 kDa and 8.67 respectively. The molecular weight of the protein when expressed in E. coli corresponded to that expected. Northern blotting showed that B3GALT7 was highly expressed in lung, throat and ileum, whereas the expression level was low in tongue, breast, uteri, testis. In addition, it was also demonstrated that B3GALT7 is differentially transcribed in human tumor cell lines. 相似文献
187.
Jónsson TH 《Annals of botany》2004,94(5):753-762
BACKGROUND AND AIMS: Sub-arctic mountain birch Betula pubescens var. pumila communities in the North Atlantic region are of variable stature, ranging from prostrate scrubs to forests with trees up to 12 m high. Four hypotheses were tested, relating growth and population characteristics of sub-arctic birch woodland and scrub to tree stature; i.e. the variable stature of birch woods is due to differences in (1) the mean growth rate; (2) the age-related patterns of growth rate; (3) the life expectancy of stems; or (4) the tree form. Methods: A stratified random sample of 300 birch trees was drawn from the total population of indigenous birch woodlands and scrub in Iceland, yielding 286 valid sample genets. The population was divided into three sub-populations with dominant trees 0-2, 2-4 and 4-12 m tall, referred to as birch scrub, birch scrub-woodland and birch forest, respectively. KEY RESULTS: Trees in the scrub population were of more contorted growth form than birch in the scrub-woodland and forest populations. Mean growth rates, mean age and median life expectancies increased significantly with sub-population of greater tree stature. At the population level, annual increment and longevity of birch stems was apparently interrelated as the stems in vigorously growing birch sub-populations had a longer life expectancy than those of slower growth. However, no difference was observed between sub-populations in age-related patterns of extension growth rate. CONCLUSIONS: The results were consistent with hypotheses (1), (3) and (4), but hypothesis (2) was rejected. Hence, mountain birch of more vigorous growth attains a greater stature than birch of lesser increment due to faster extension growth rate and a longer lifespan. In addition, the more contorted stem form of scrub populations contributes to their low stature. 相似文献
188.
Diversity of G proteins in Lepidopteran cell lines: partial sequences of six G protein alpha subunits 总被引:2,自引:0,他引:2
The aim of this work was to sample the diversity of G protein alpha subunits in lepidopteran insect cell lines. Here we report the amplification by degenerate PCR of partial sequences representing six G protein alpha subunits from three different lepidopteran insect cell lines. Sequence comparisons with known G protein alpha subunits indicate that the Sf9, Ld and High Five cell lines each contain (at least) one Galpha(q)-like and one Galpha(i)-like Galpha subunit. All six PCR products are unique at the nucleotide level, but the translation products of the three Galpha q-like partial clones (Sf9-Galpha 1, Ld-Galpha 1, and Hi5-Galpha 1) are identical, as are the translation products of the three Galpha i-like partial clones (Sf9-Galpha 2, Ld-Galpha 2, and Hi5-Galpha 2). Both the Galpha(q)-like and Galpha(i)-like translation products are identical to known Galpha subunits from other Lepidoptera, are highly similar (88-98%) to Galpha subunits from other invertebrates including mosquitoes, fruit flies, lobsters, crabs, and snails, and are also highly similar (88-90%) to known mammalian Galpha subunits. Identification of G protein alpha subunits in lepidopteran cell lines will assist in host cell line selection when insect cell lines are used for the pharmacological analysis of human GPCRs. 相似文献
189.
Nuki Y Uchinokura S Miyata S Fukushima T Hamasuna R Nakano S Wakisaka S Akiyama Y Itoh H Kataoka H 《Human cell》2004,17(3):145-150
A cell line designated NYGM was established from a human cerebral glioblastoma multiforme (GBM) obtained from a 75-year-old Japanese woman. The cell line has grown slowly without interruption and has been propagated continuously by serial passages (more than 80 passage) during the past 3 years. The cultured cells were fusiform or polyhedral in shape. The population doubling time was 24 hours. The chromosomal number varied between 77 and 88, with modal chromosomal number of 84. NYGM cells concomitantly expressed MET receptor tyrosine kinase (a product of c-met protooncogene) and its ligand HGF/SF (hepatocyte growth factor/scatter factor), as well as HGF activator and HGF activator inhibitors. The cells might be useful for the study of pericellular regulation of HGF/SF-MET signaling and HGF activation of GBM cells. 相似文献
190.
An anchorage-dependent Wilms' tumor cell line, HFWT, has been found to be extremely susceptible to human natural killer (NK) cells. Here we established a transfectant of HFWT with the green fluorescence protein (GFP) gene, designated GHINK-1 cells, to apply to the activated NK cytotoxicity assay without radioisotope labeling. After being co-cultured with CD3 CD56+ NK cells, GHINK-1 cells released GFP into the medium. The intensity of the fluorescence from the released GFP correlated almost exactly with the radioactivity of a standard 51Cr-release assay performed with suspension-cultured K562 cells. Because it does not require separation of the remaining live target cells by centrifugation, the non-radioisotopic GFP release assay with GHINK-1 cells is a convenient alternative for monitoring human activated NK killing activity. 相似文献