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The reputedly obligately organotrophic Thiobacillus ferrooxidans KG-4 cultured on glucose contained a small proportion of cells which grew autotrophically on ferrous-iron. 相似文献
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In an attempt to study mutagenesis in human diploid fibroblasts, clones derived from mass cultures treated with mutagen have been examined by starch-gel electrophoresis for 43 different enzyme loci. A technique of mutagen treatment was devised which facilitated the cloning and which enabled the cells to be exposed to very high doses of EMS and MNNG. Two alterations in phenotype, presumably the result of mutation, were observed, one involving peptidase D (PEPD) and the other phosphoglucomutase (PGM1). 相似文献
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Intragenic Sequences Affect the Expression of the Gene Encoding Glial Fibrillary Acidic Protein 总被引:6,自引:1,他引:5
We show that the expression of the gene encoding glial fibrillary acidic protein (GFAP) gene is affected by at least three cis-acting elements. A positive regulatory element that is located between nucleotides -1,631 and -1,479 can confer cell type-specific expression on a heterologous gene. A second regulatory element is located between nucleotides -97 and -80. The third is a negative regulatory element that is located within the first intron of the gene. Deletion of this element activates GFAP expression in HeLa cells, and affects promoter function in glioma cells. 相似文献
98.
A new species,Nyssa talamancana, with fruits larger than those of any other, either living or fossil, is described from Costa Rica and Panama. In size, number
of germination valves, and surface-sculpturing, its endocarps resemble those of the fossil assemblage more than those of the
other living species. The occurrence of this distinctive new member of a definitely Laurasian family, in association with
other endemic or nearly endemic Laurasian taxa, at wet mid-elevations lends credence to the idea that these forests harbor
remnants of the really ancient flora of southern Central America. 相似文献
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Martin D. Cassell Nicholas J. Mankovich Thackery S. Gray Terence H. Williams 《Peptides》1982,3(3):283-290
When viewed under dark-field illumination, peptidergic terminals in sections stained by the Sternberger PAP immunocytochemical method are seen as individual points of light. Under high magnification, the degree of brightness of various areas of immunoreactive terminals is seen to be a function of the density of terminals in these areas. By analyzying the relative brightness of the immunostained central nucleus of the amygdala (CNA) with an EyeCom II PDP- image analysis system, we have obtained a relative evaluation of the density distribution of neurotensin (NT)-, substance P (SP), VIP-, angiotensin II (AII), m-enkephalin (m-ENK) and somatostatin (SS)-immunoreactive terminals in terms of normal morphology and following a brain lesion. The EyeCom II system divides the presented image into 307200 picture elements (pixels) and assigns one of 256 grey values to the average brightness with each pixel. We have aggregated the grey level frequencies into 5 levels where level 1 corresponds to the highest terminal density and level 5 to the lowest density. At level 1, only NT- and VIP-immunoreactive terminals occupy a significant percentage of the cross-sectional area of the CNA (20%). About 15% of the area of the CNA has VIP terminals with level 5 density. The distributions of the top 20% of the terminal density range of NT, SP, AII and VIP support a classical medial/lateral division of the nucleus. The distribution of the same range of SS- and ENK terminals suggests a dorsoventral division of the CNA. A preliminary study indicates that comparison of grey level frequency histograms generated by image analysis from homologous lesioned and unlesioned sections of the CNA can yield useful information regarding post-lesion changes in the distribution of immunoreactive terminals. 相似文献