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71.
Michele Yarnall Kathleen J. Reis Elia M. Ayoub Michael D.P. Boyle 《Journal of microbiological methods》1984,3(2):83-93
A rapid semiquantitative procedure that enables bacteria to be screened for surface or secreted receptors for the Fc region of human IgG is described. Surface Fc receptors were detected by direct transfer of bacterial colonies to nitrocellulose by electroblotting and then probing with 125I-labeled human IgG in the presence of a two fold molar excess of unlabeled F(ab′)2fragments. The blots were exposed to X-ray film and the intensity of the resulting autoradiograph was a measure of surface Fc receptors expression. This procedure reliably distinguished Staphylococcus aureus strains which expressed different levels of surface Fc receptors. When applied to the study of group A streptococci, a number of Fc receptor-positive strains were identified. Unlike the homogeneous Fc receptor expression on individual colonies of the staphylococcal strains, a wide variation in the level of Fc receptor expression was observed within a given streptococcal strain. Group A streptococcal substrains which expressed high and low levels of surface Fc receptors could be isolated from replica plates.Secreted Fc receptors were measured by a simple modification of the blotting procedure in which the nitrocellulose was placed on the opposite side of the agar from the bacterial colonies. Secreted Fc receptors was electroblotted through the agar onto nitrocellulose and probed as described above. This approach readily detected nanogram quantities of secreted type I Fc receptor (protein A) from the Staphylococcus aureus Cowan strain. None of the group A streptococcal strains tested were found to secrete detectable quantities of Fc receptors. 相似文献
72.
Kathleen Dobrosielski-Vergona 《In vitro cellular & developmental biology. Plant》1984,20(11):889-892
Summary Glucose-6-phosphatase activity decreases whereas gamma glutamyltranspeptidase activity increases during hepatocarcinogenesis
and the maintenance of hepatocytes in primary culture. This report describes the effect of culture conditions that are known
to preserve hepatic glucose-6-phosphatase activity on gamma glutamyltranspeptidase activity. The results indicate that the
regulation of glucose-6-phosphatase and gamma glutamyltranspeptidase activities is not coordinated in primary cultures of
hepatocytes.
This work was supported by a grant from the USPHS, NIH grant AG00439 awarded to Dr. Christopher C. Widnell and a Category
I Research Development Award from the University of Pittsburgh to Dr. Kathleen Dobrosielski-Vergona.
Editor's Statement Information communicated in this article contributes to a greater understanding of the mechanisms regulating
liver cell metabolism and provides some further insight concerning the complexity of the controls involved in vitro, and presumably
in vivo. David W. Barnes 相似文献
73.
Matthew J. Friedman Ante M. Krstulović Henri Colin Georges Guiochon Kathleen Pajer 《Analytical biochemistry》1984,142(2):480-486
Described in this paper is a rapid, isocratic assay for serum indole-3-acetic acid (IAA). The sample preparation involves only protein precipitation using sulfosalicylic acid, and the sensitivity of amperometric detection is in the picogram range. The chromatographic analysis time is approximately 4 min. The devised method was used for a longitudinal study of IAA levels in serum samples from control subjects and newly abstinent alcoholics. Dietary variations were eliminated by administering a 2.0-g loading dose of L-Trp to all subjects investigated. The results are presented in the form of cumulative frequency polygons. Preliminary data indicate no differences in IAA levels between newly abstinent alcoholics and control subjects. 相似文献
74.
Starting with anEscherichia coli strain containingglyT56, a glycine transfer RNA suppressor of the arginine codons AGA and AGG, and atrpA mutant containing lysine at position 211 of the tryptophan synthetase alpha chain, we have isolated AAG-suppressors that
fall into two classes. In class 1 are dominant suppressors that arose with the simultaneous loss ofglyT56 activity. They are approximately 50% cotransducible withargE, as isglyT, and appear to be derived fromglyT56. Class 2 suppressors, located betweenpurE andtrp on theE. coli map, are not near any glycine tRNA genes, and may represent novel missense suppressors. 相似文献
75.
Summary The major organelles within the cells of maleBangia atropurpurea (Roth) C. Ag. filaments undergo a series of ultrastructural transformations during the production of spermatia. Initially, thylakoids within the large axial chloroplast develop a reticulate pattern commencing at the central pyrenoid region. Subsequent changes involve loss of lobes and diminution of volume through division; chloroplasts in final stages contain a few dilated, distorted thylakoids and many plastoglobuli. During differentiation the large nucleolus disappears from the nucleus and four masses of chromatin aggregate near the nuclear envelope. Furrows originating from the nuclear envelope form double membranes around each of the chromatin masses and most of the nucleoplasm is eliminated. Several types of fibrillar vesicles are formed during the process and large floridean starch reserves are utilized. Multilamellar bodies and microbody-like structures occur within the cells during certain phases of spermatiogenesis. 相似文献
76.
The inverted repeats of Tn5 are functionally different 总被引:72,自引:0,他引:72
The inverted repeats of Tn5, which have identical restriction endonuclease cleavage patterns, have different functional properties. They differ with respect to RNA polymerase binding, full promotion of neomycin resistance, the polypeptides coded for by the repeats and their function in the transposition process. There is a week RNA polymerase binding site present in one repeat and not in the other which seems to be important for neomycin resistance. The two inverted repeats code for polypeptides of different molecular weights, with each repeat appearing to encode two polypeptides. The polypeptides from only one of the repeats of Tn5 appear to be absolutely required for Tn5 transposition. 相似文献
77.
Both muscular and respiratory biofeedback procedures have been employed in attempts to reduce symptoms of bronchial asthma. Research relating to these approaches is reviewed in the present article. Biofeedback training both for facial muscle relaxation and for respiratory resistance decrease improves short-term pulmonary function in asthmatic individuals. These forms of training represent promising avenues for the management of asthma. However, unqualified endorsement of these procedures is premature, at the present time, since their influence on asthma-related variables other than pulmonary function has not been determined and since their long-term effects have not been investigated. 相似文献
78.
Michael Salmon Gary Hyatt Kathleen McCarthy John D. Costlow 《Ethology : formerly Zeitschrift fur Tierpsychologie》1978,48(3):251-276
The factors responsible for reproductive isolation between two sibling species of fiddler crabs (Uca pugilator and U. panacea) were studied under both laboratory and field conditions. ♂♂ showed species differences in their visual and acoustical displays. These differences were exaggerated in the overlap zone, where U. pugilator showed character displacement of its acoustic signals. ♀♀ of U. pugilator confined with ♂♂ of U. panacea produced fewer clutches of young. Occasionally, forced matings took place in the laboratory, resulting in hybrids suffering greater mortality through development. The data indicate that both premating (behavioral) as well as postmating (higher larval mortality) barriers act to prevent interbreeding. 相似文献
79.
The present studies explored the role of adherent cells in tumor immunity. Lymph node cells from mice bearing large tumors appeared to be maximally stimulated in vivo and incapable of further stimulation by cells of the same tumor in vitro. Removal of the adherent cell population resulted in a marked decrease in the spontaneous background activity of the remaining nonadherent cells and allowed these cells to undergo stimulation when cultured in the presence of mitomycin-blocked tumor cells. The role of the adherent cell in the maintenance of a state of continuous stimulation was further elucidated by experiments in which lymph node cell populations were reconstituted from the adherent and nonadherent subpopulations. It was also shown that adherent lymphoid cells from tumor-bearing mice, but not from normal mice, were capable of stimulating tumor-immune lymphocytes in a manner similar to intact mitomycin-blocked tumor cells. 相似文献
80.