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71.
Binding, internalization and intracellular processing of 125I-epidermal growth factor purified by isoelectric focusing 总被引:1,自引:0,他引:1
B E Magun S R Planck L M Matrisian J S Finch 《Biochemical and biophysical research communications》1982,108(1):299-306
When epidermal growth factor (EGF) which had been extensively purified by HPLC was subjected to iodination with sodium 125iodide, 5 major species of differing isoelectric points were produced. Some of these species bound to rat fibroblasts with different affinities but were internalized with equal efficiency. Examination of the internalized 125I-labelled molecules revealed processing of all the 125I-EGF species to macromolecules with more acidic isoelectric points. The 125I-EGF species with a pI of 4.5 corresponded in electrofocusing behavior with intact non-iodinated EGF. Other EGF species probably represented molecules which were covalently modified as a result of the iodination procedure. 相似文献
72.
Bruce Manchon 《Soil & Sediment Contamination》1992,1(4):321-338
An effective groundwater monitoring system can be implemented by the combined utilization of cone penetrometer (CPT), HydroPunch® sampling, and borehole geophysical methods. The combined techniques provide a cost‐effective method for the design of a groundwater monitoring system for geologists or hydrogeologists assessing a site. With the relatively high costs associated with determining groundwater quality for site assessments, coupled with regulatory agency compliance, these combined methods can provide an effective edge in an increasingly competitive environmental industry. CPT combined with HydroPunch sampling can delineate the horizontal and vertical extent and concentration of a contaminant plume, define the extent and thickness of a free product plume, define soil and aquifer characteristics, and aid in the proper selection of well location and screen placement. The use of borehole geophysics further enhances the interpretation provided from the CPT. The interpretation of borehole geophysics provides additional information about the deposition regime of the area of investigation and a more detailed investigation of the stratigraphy. The CPT and HydroPunch can be used in unconsolidated sediments, and HydroPunch sampling can be combined with a hollow‐stem auger system. Borehole geophysics can be run in almost any environment. CPT and borehole geophysics provide information on specific lithologic characteristics necessary to obtain a groundwater sample from vertically separated aquifers. The HydroPunch can obtain a discrete, chemically representative groundwater sample from the targeted aquifer. CPT and borehole geophysics can also be used to determine lithology and for correlation of equivalent stratas from one borehole or well to the next. Borehole geophysical interpretation also provides a means of determining not only the stratigraphy and lithology but also the aquifer parameters and the type of fluids in the aquifer. Hydrogeologic and geologic data obtained from using these three methods can be employed to maximize the cost‐effectiveness and design efficiency of a groundwater monitoring system. Proper location of wells and screened interval placements are determined by a coherent design process rather than by random chance. Two studies demonstrating the combined applications of CPT, HydroPunch, and borehole geophysics for the design and placement of groundwater monitoring wells are presented in the following discussion. 相似文献
73.
Eric P. Krenning Roel Docter Bert Bernard Theo Visser Georg Hennemann 《FEBS letters》1982,140(2):229-233
74.
An immobilized cyclic multi-step enzyme system -- the urea cycle 总被引:1,自引:0,他引:1
75.
Summary Ornithine decarboxylase activity was measured during organogenesis in rat embryos grown in utero and whole rat conceptuses
maintained in an in vitro culture system. Ornithine decarboxylase levels in vivo showed a distinct peak at embryonic age 10.5
d. Despite identical morphology, protein content, crown rump length and numbers of somites cultured embryos displayed a different
developmental pattern and possessed less than half the ODC activity of that in vivo. The data suggest that the normal embryonic
programming of ODC activity is significantly altered by the culture environment and that further biochemical comparisons of
embryos growing in utero and in vitro may be required to evaluate properly the applicability of this technique to detailed
studies of teratogenesis and developmental biology.
This work was supported by NIH-5-507-RR5359-17 and a 1980 Research Starter Grant from the Pharmaceutical Manufacturers Association
Foundation. 相似文献
76.
77.
Using BrdU-labeling and acridine orange staining, the behavior of X-chromosome replication was studied in 28 XXX and 19 XXY digynous mouse triploids. In some of these the paternal and maternal X chromosome could by cytologically distinguished. Such embryos were obtained by mating chromosomally normal females with males carrying Cattanach's X chromosome which contains an autosomal insertion that substantially increases the length of this chromosome. In the XXX triploids there were two distinct cell lines, one with two late-replicating X chromosomes, and the other with only one late-replicating X. The XXY triploids were also composed of two cell populations, one with a single late-replicating X and the other with no late replicating X chromosome. Assuming that the late-replicating X is genetically inactive, in both XXX and XXY triploids, cells from the embryonic region tended to have only one active X chromosome, whereas those from the extra-embryonic membranes tended to have two active X chromosomes. The single active X chromosome was either paternal or maternal in origin, but two active X chromosomes were overwhelmingly maternal in origin, suggesting paternal X-inactivation in extra-embryonic tissues. 相似文献
78.
James C. Fuscoe J.Patrick ONeill Richard Machanoff Abraham W. Hsie 《Mutation research》1982,96(1):15-30
We describe an assay for the quantification of reverse mutations at the hypoxanthine-guanine phosphoribosyltransferase (hgprt) locus in Chinese hamster ovary cells utilizing the selective agent L-azaserine (AS). Conditions are defined in terms of optimal AS concentration, cell density, and phenotypic expression time. After treatment, replicate cultures of 106 cells are allowed a 48-h phenotypic expression time in 100-mm plates. AS (10 μM) is then added directly to the growing culture and AS-resistant (ASr) cells form visible colonies. This assay is used to quantify ICR-191-, ICR-170-, and N-ethyl-N-nitrosourea-induced reversion of independently isolated HGPRT? clones. The ASr phenotype is characterized both physiologically and biochemically. All ASr clones isolated are stably resistant to AS and aminopterin but sensitive to 6-thioguanine. They also have re-expressed HGPRT enzyme. In addition, several revertants are shown to contain altered HGPRT. The data provide further evidence that ICR-191 and ICR-170 cause structural gene mutations in mammalian cells and also suggest that ICR-191, ICR-170, and N-ethyl-N-nitrosourea induce similar types of mutations in Chinese hamster ovary cells. 相似文献
79.
Summary The possibility that the somatostatin cells are derived from the neurectoderm has been questioned in avian embryos. Isotopic and isochronic transplantations of the neural primordium from quail into chick embryos were made at the vagal level (somites 1 to 7). Quail and chick cells can be distinguished by the structure of their nucleus. The somatostatin cells were characterized immunocytochemically. In no case did quail cells showing the immunological reaction originate from the neural crest. 相似文献
80.
Lipoxygenbase-derived products of arachidonic acid mediate stimulation of hexose uptake in human polymorphonuclear leukocytes 总被引:3,自引:0,他引:3
D A Bass M J Thomas E J Goetzl L R DeChatelet C E McCall 《Biochemical and biophysical research communications》1981,100(1):1-7
The titration of metal-freed bovine α-lactalbumin with Mg2+ ions causes a two-stepped decrease in the tryptophan fluorescence quantum yield and a pronounced spectral shift towards shorter wavelengths, which seems to be a result of the binding of two magnesium ions to the protein molecule. The magnesium binding constants evaluated from the fluorimetric Mg2+-titration are 2·103 and 2·102 M?1. Mg2+ ions in millimolar concentrations almost do not influence the binding of Ca2+ ions to the protein. 相似文献