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381.
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383.
C B Bagwell J L Hudson G L Irvin 《The journal of histochemistry and cytochemistry》1979,27(1):293-296
A nonparametric statistical test for the analysis of flow cytometry derived histograms is presented. The method involves smoothing and translocation of data, area normalization, channel by channel determination of the mean and S.D., and use of Bayes' theorem for unknown histogram classification. With this statistical method, different sets of histograms from numerous biological systems can be compared. 相似文献
384.
Pokeweed antiviral protein inactivates pokeweed ribosomes; implications for the antiviral mechanism 总被引:9,自引:0,他引:9
Maureen S. Bonness Michael P. Ready James D. Irvin Tom J. Mabry 《The Plant journal : for cell and molecular biology》1994,5(2):173-183
Pokeweed antiviral protein (PAP) and other ribosome-inactivating proteins (RIPs) had previously been thought to be incapable of attacking conspecific ribosomes, thus having no effect on endogenous processes. This assertion conflicts with a model for PAP's in vivo antiviral mechanism in which PAP (a cell wall protein) selectively enters virus-infected cells and disrupts protein synthesis, thus causing local suicide and preventing virus replication. We show here that pokeweed ( Phytolacca americana ) ribosomes, as well as endod ( Phytolacca dodecandra ) ribosomes, are indeed highly sensitive to inactivation by conspecific RIPs. Ribosomes isolated from RIP-free pokeweed and endod suspension culture cells were found to be highly active in vitro , as measured by poly(U)-directed polyphenylalanine synthesis. Phytolacca ribosomes challenged with conspecific RIPs generated doseresponse curves (IC50 of 1 nM PAP or dodecandrin) very similar to those from wheat germ ribosomes. To determine if Phytolacca cells produce a cytosolic 'anti-RIP' protective element, ribosomes were combined with Phytolacca postribosomal supernatant factors from culture cells, then challenged with conspecific RIPs. Resulting IC50 values of 3–7 nM PAP, PAP-II, PAP-S or dodecandrin indicate that supernatants from these Phytolacca cells lack a ribosomal protective element. This research demonstrates that PAP inactivates pokeweed ribosomes (and is therefore potentially toxic to pokeweed cells) and supports the local suicide model for PAP's in vivo antiviral mechanism. The importance of spatial separation between PAP and ribosomes of cells producing this RIP is emphasized, particularly if crop plants are transformed with the PAP gene to confer antiviral protection. 相似文献
385.
Chemical modifications of pokeweed antiviral protein: effects upon ribosome inactivation, antiviral activity and cytotoxicity 总被引:2,自引:0,他引:2
Pokeweed antiviral protein (PAP) is a protein known to inactivate eukaryotic ribosomes by an unknown enzymatic action and inhibit the production of mammalian viruses in tissue culture. This protein was subjected to a variety of chemical modifications to determine their effects upon ribosomal inactivation, antiviral action, and cytotoxicity. It was found that modifications of a number of different amino acid residues had similar effects upon all 3 activities. Also the inactivation of PAP with diethylpyrocarbonate was not due to its reaction with a histidine residue but to a modification of an unidentified amino acid residue. 相似文献
386.
Joseph A. DAnna Irvin Isenberg 《Biochemical and biophysical research communications》1974,61(1):343-347
Ultracentrifuge measurements show that the individual histones f2a1 and f3 interact to form tetramers in solution. The conditions which facilitate renaturation are discussed. 相似文献
387.
A simple and rapid method for minipreparation of DNA from tissue cultured plant cells 总被引:9,自引:0,他引:9
Irvin J. Mettler 《Plant Molecular Biology Reporter》1987,5(3):346-349
388.
Measurement of the effects of drugs, mediators and infectious agents on various models of lung disease, as well as assessment of lung function in the intact mouse has the potential for significantly advancing our knowledge of lung disease. However, the small size of the mouse presents significant challenges for the assessment of lung function. Because of compromises made between precision and noninvasiveness, data obtained may have an uncertain bearing on the mechanical response of the lung. Nevertheless, considerable recent progress has been made in developing valid and useful measures of mouse lung function. These advances, resulting in our current ability to measure sophisticated indices of lung function in laboratory animals, are likely to lead to important insights into the mechanisms of lung disease. 相似文献
389.
390.
Iso-accepting forms of tRNAmet, tRNAleu, tRNAlys, and tRNAtyr were isolated from combined walls and septa of tomato fruits at 5 consecutive stages of ethylene induced ripening. Changes in the relative amount of some tRNAleu and tRNAlys were discerned 10hr after exposure to ethylene. Individual patterns of change for each of several iso-acceptor tRNAs were evident throughout the ripening sequence. Maximal changes were: tRNAlys, ?66.3%; tRNAleu, ?24.8%; and tRNAmet, +26.7%. 相似文献