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101.
Transgenetic studies implicate interactions between homologous PrP isoforms in scrapie prion replication 总被引:55,自引:0,他引:55
S B Prusiner M Scott D Foster K M Pan D Groth C Mirenda M Torchia S L Yang D Serban G A Carlson 《Cell》1990,63(4):673-686
Transgenic (Tg) mice expressing both Syrian hamster (Ha) and mouse (Mo) prion protein (PrP) genes were used to probe the mechanism of scrapie prion replication. Four Tg lines expressing HaPrP exhibited distinct incubation times ranging from 48 to 277 days, which correlated inversely with HaPrP mRNA and HaPrPC. Bioassays of Tg brain extracts showed that the prion inoculum dictates which prions are synthesized de novo. Tg mice inoculated with Ha prions had approximately 10(9) ID50 units of Ha prions per gram of brain and less than 10 units of Mo prions. Conversely, Tg mice inoculated with Mo prions synthesized Mo prions but not Ha prions. Similarly, Tg mice inoculated with Ha prions exhibited neuropathologic changes characteristic of hamsters with scrapie, while Mo prions produced changes similar to those in non-Tg mice. Our results argue that species specificity of scrapie prions resides in the PrP sequence and prion synthesis is initiated by a species-specific interaction between PrPSc in the inoculum and homologous PrPC. 相似文献
102.
Functional antagonism between oncoprotein c-Jun and the glucocorticoid receptor 总被引:121,自引:0,他引:121
R Schüle P Rangarajan S Kliewer L J Ransone J Bolado N Yang I M Verma R M Evans 《Cell》1990,62(6):1217-1226
103.
Novel method to extract large amounts of bacteriocins from lactic acid bacteria. 总被引:18,自引:5,他引:13 下载免费PDF全文
Antimicrobial peptides, bacteriocins, produced by lactic acid bacteria were adsorbed on the cells of producing strains and other gram-positive bacteria. pH was a crucial factor in determining the degree of adsorption of these peptides onto cell surfaces. In general, between 93 and 100% of the bacteriocin molecules were adsorbed at pHs near 6.0, and the lowest (< or = 5%) adsorption took place at pH 1.5 to 2.0. On the basis of this property, a novel isolation method was developed for bacteriocins from four genera of lactic acid bacteria. By using this method we made preparations of pediocin AcH, nisin, sakacin A, and leuconocin Lcm1 that were potent and concentrated. This method produced a higher yield than isolation procedures, which rely on precipitation of the bacteriocins from the cell-free culture liquor. It is simple and can be used to produce large quantities of bacteriocins from lactic acid bacteria to be used as food biopreservatives. 相似文献
104.
M F Canto M M Oliva J J Potter E Mezey V W Yang 《Biochemical and biophysical research communications》1992,188(2):684-689
The activity of the rat class I alcohol dehydrogenase (ADH) is enriched in certain tissues including the liver, intestine and testis. The tissue-specific expression of the gene encoding ADH in the rat was studied and found to closely correlate with tissue isozymic activity. A factor designated enhancer-site downstream binding protein (EDBP) was recently identified in the rat liver and found to interact with the proximal promoter of the class I ADH gene. The distribution of EDBP in nuclear extracts obtained from various tissues was examined based on its sequence-specific DNA binding property and found to correlate with tissue ADH expression. These findings suggest that EDBP is potentially a positive regulatory factor which is involved in controlling the tissue-specific expression of the ADH gene. 相似文献
105.
本文描述了云南省条鳅亚科鱼类一新属和一新种。根据形态特征并结合区系间的相互关系,探讨了属的分类地位。 相似文献
106.
An effort to identify the major general esterases of rat liver cytosol that are insensitive to the serine esterase inhibitor paraoxon (diethyl 4-nitrophenyl phosphate) has led to the isolation of a dozen enzymes. Four of these are electrophoretically homogeneous. Although purified on the basis of their hydrolytic activity toward 4-nitrophenyl acetate, each of the enzymes has a very broad and overlapping substrate specificity for aromatic esters. Thiol esters serve as substrates but, within the limits of the methods used, amides are not hydrolyzed. 相似文献
107.
108.
Identification of overlapping DNA-binding and centromere-targeting domains in the human kinetochore protein CENP-C. 总被引:9,自引:0,他引:9 下载免费PDF全文
C H Yang J Tomkiel H Saitoh D H Johnson W C Earnshaw 《Molecular and cellular biology》1996,16(7):3576-3586
The kinetochore in eukaryotes serves as the chromosomal site of attachment for microtubules of the mitotic spindle and directs the movements necessary for proper chromosome segregation. In mammalian cells, the kinetochore is a highly differentiated trilaminar structure situated at the surface of the centromeric heterochromatin. CENP-C is a basic, DNA-binding protein that localizes to the inner kinetochore plate, the region that abuts the heterochromatin. Microinjection experiments using antibodies specific for CENP-C have demonstrated that this protein is required for the assembly and/or stability of the kinetochore as well as for a timely transition through mitosis. From these observations, it has been suggested that CENP-C is a structural protein that is involved in the organization or the kinetochore. In this report, we wished to identify and map the functional domains of CENP-C. Analysis of CENP-C truncation mutants expressed in vivo demonstrated that CENP-C possesses an autonomous centromere-targeting domain situated at the central region of the CENP-C polypeptide. Similarly, in vitro assays revealed that a region of CENP-C with the ability to bind DNA is also located at the center of the CENP-C molecule, where it overlaps the centromere-targeting domain. 相似文献
109.
A novel type of DNA-binding protein interacts with a conserved sequence in an early nodulin ENOD12 promoter 总被引:3,自引:0,他引:3
110.
We investigated the metabolism and translocation of two gibberellins(GAs), [3H]GA20 and [3H]GA1, which were applied at low concentrationto the cotyledons of Pharbitis nil (cv. Violet). Seedlings weregrown under three different photoperiodic conditions: continuouslight (CL-CL), continous light followed by short day conditions(CL-DT) and long day conditions followed by short day conditions(DT-DT). Translocation of the applied [3H]GAs from cotyledonsto hypocotyls was promoted by DT for all GAs examined. Whilethe conversion of the translocated [3H]GA1 to [3H]GA8 and itsconjugates was rapid in hypocotyl, the conversion of translocated[3H]GA20 to [3H]GA29 was slow. Radioactivity in epicotyls wasdetected much more rapidly on application of [3H]GA20 than of[3H]GA1, [3H]GA8 and [3H]GA29 and their conjugates. The conversionof [3H]GA20 to [3H]GA1 in the epicotyl was more rapid underCL-CL conditions. This result in consistent with the higherlevel of endogenous GA1 existing in epicotyls under CL-DT thanDT-DT conditions. However, when [3H]GA1 was applied to the cotyledon,only small amounts of [3H]GA8 and its conjugates were detectedin the epicotyl regardless of the photoperiodic conditions.This result may suggest that the translocation and metabolismof [3H]GA20 from cotyledons to epicotyl was faster under CL-CLthan DT-DT conditions and may correlate with the increased epicotylelongation of GA20 treated plants under CL-DT than DT-DT conditions. (Received June 28, 1995; Accepted November 2, 1995) 相似文献