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511.
A procedure for continuous measurement of 14CO2 production by cultured cells grown in Leighton tubes has been described. The apparatus developed also permits aliquots of the incubation medium to be taken during the experiments for analysis of labeled metabolites released into the solution. A simple method for determination of [14C]lactic acid in such aliquots has been described. The reproducibility and usefulness of the apparatus has been demonstrated by incubating fibroblasts with glucose labeled in the C-1 or C-6 position, and examining the effects of selected drugs on CO2 and lactic acid production. 相似文献
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M A Llorens M J Bermejo M C Salcedo A L Charro M Puente 《Journal of steroid biochemistry》1989,34(1-6):505-509
The incidence and levels of epidermal growth factor receptor (EGFR) were studied in 67 breast tumors and 22 endometrial carcinomas. Estrogen receptors (ER) were also measured in all samples and progesterone receptors (PR) were analyzed in 57 breast samples and 21 endometrial tumors. A high level of EGFR expression is found in both breast and endometrial carcinomas, although the incidence of EGFR content is greater in breast carcinomas. 36% of breast tumors had EGFR at levels 3-49.5 fmol/mg membrane protein, whereas this percentage of positivity was 27% for endometrial tumors. In 51% of breast carcinoma and 73% of endometrial tumors, there was a positive ER content, whereas 53% of breast tumors and 62% of endometrial carcinomas were positive. A clear inverse relationship between EGFR content and ER and PR status has been observed in breast tumors. Our data confirm the previously described inverse correlation between expression of EGFR and estrogen receptors in human breast cancer. We also show here that there is a similar inverse relationship between EGFR content and ER levels in endometrial tumors. 相似文献
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Heike Heklau Nicole Schindler Franois Buscot Nico Eisenhauer Olga Ferlian Luis D. Prada Salcedo Helge Bruelheide 《Ecology and evolution》2021,11(10):5424
- Recent studies found that the majority of shrub and tree species are associated with both arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) fungi. However, our knowledge on how different mycorrhizal types interact with each other is still limited. We asked whether the combination of hosts with a preferred association with either AM or EM fungi increases the host tree roots’ mycorrhization rate and affects AM and EM fungal richness and community composition.
- We established a tree diversity experiment, where five tree species of each of the two mycorrhiza types were planted in monocultures, two‐species and four‐species mixtures. We applied morphological assessment to estimate mycorrhization rates and next‐generation molecular sequencing to quantify mycobiont richness.
- Both the morphological and molecular assessment revealed dual‐mycorrhizal colonization in 79% and 100% of the samples, respectively. OTU community composition strongly differed between AM and EM trees. While host tree species richness did not affect mycorrhization rates, we observed significant effects of mixing AM‐ and EM‐associated hosts in AM mycorrhization rate. Glomeromycota richness was larger in monotypic AM tree combinations than in AM‐EM mixtures, pointing to a dilution or suppression effect of AM by EM trees. We found a strong match between morphological quantification of AM mycorrhization rate and Glomeromycota richness.
- Synthesis. We provide evidence that the combination of hosts differing in their preferred mycorrhiza association affects the host''s fungal community composition, thus revealing important biotic interactions among trees and their associated fungi.
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Detection of β‐exotoxin synthesis in Bacillus thuringiensis using an easy bioassay with the nematode Caenorhabditis elegans 下载免费PDF全文
519.
Lily Lee Salcedo Carl Franzblau 《In vitro cellular & developmental biology. Plant》1981,17(2):114-120
Summary This study describes the ability of aortic smooth muscle cells to synthesize and accumulate collagen with time in culture.
Inasmuch as smooth muscle cell cultures multilayer and continue to divide, albeit slowly, and can be maintained in the same
vessels where seeded for extended periods of time, a long-term aging study from a single subcultivated population of cells
was carried out. This is different from the usual cell-culture aging achieved by an increase in cell population doublings
obtained by repeated subcultivations. The latter process, which is trypsin induced, involves a changing cellular environment
including the extracellular matrix that is produced by the cells in culture.
Second subcultures of weanling rabbit, aortic media, smooth muscle cells maintained for different periods of time up to 14
wk displayed decreasing hydroxyproline formation with time. Proline hydroxylation was determined by pulsing these second-passage
cells with [14C]proline for 24 h at various times during the 14 wk period. The cell layer and medium were evaluated separately for radioactive
proline and hydroxyproline and the medium for bacterial collagenase-susceptible protein as well. The percent of hydroxylation
in the medium decreased from >31% within 1 wk after plating to 15.2% after 14 wk in culture. The percent of collagenase-susceptible
protein in the medium decreased in a comparable manner. The DNA levels increased during the entire period although initially
somewhat more rapidly. Accumulation of protein in the extracellular matrix continued during the 14-wk span. The accumulation
of hydroxyproline in the extracellular matrix also continued to increase throughout the culture period, but it did slow down
significantly. Yet the cells appear not to have lost their ability to accumulate connective tissue and protein in the insoluble
cell layer. The data suggest clearly that the percent collagen synthesis relative to total protein synthesis decreases in
the older cultures; total protein synthesis also decreases as expected.
This study was supported by NIH Program Projects AG00001 and HL 13262. 相似文献