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71.
Sukla Ghosh Patricia W. Oten Shymali Mukherjee Salil K. Das 《Molecular and cellular biochemistry》1991,101(2):157-166
Summary We have reported earlier that cholinephosphotransferase (EC 2.7.8.2) is present in both mitochondria and microsomes of fetal guinea pig lung. This study was designed to compare the properties of mitochondrial and microsomal cholinephosphotransferase in fetal guinea pig lung. Various parameters, such as substrate specificity, Km values, sensitivity to N-ethylmaleimide, dithiothreitol and trypsin were measured. Both showed significant preference for unsaturated diacylglycerols over saturated diacylglycerols. Data on Km and Vmax indicate that the affinity of this enzyme for different diacylglycerols varies between the two forms. The ID50 values for N-ethylmaleimide were 20 mM and 12.5 mM for the mitochondrial and microsomal form of the enzyme, respectively. Dithiothreitol showed an inhibitory effect on both; however, the mitochondrial form was inhibited less than the microsomal form. The effects of N-ethylmaleimide and dithiothreitol on both forms of enzyme indicated that the microsomal cholinephosphotransferase requires a higher concentration of -SH for its activity than the mitochondrial enzyme does. The enzyme was inhibited by trypsin in both mitochondria and microsome under isotonic condition suggesting that this enzyme is on the outside of the membrane in both endoplasmic reticulum and mitochondria. 相似文献
72.
Dr. Timothy J. Barrett James H. Green Patricia M. Griffin Andrew T. Pavia Stephen M. Ostroff I. Kaye Wachsmuth 《Current microbiology》1991,23(4):189-195
Shiga-like toxin-producingEscherichia coli O157:H7 are important causes of bloody diarrhea and hemolytic uremic syndrome. To facilitate the epidemiologic study of these organisms, we developed enzyme-linked immunosorbent assays (ELISAs) for antibodies to Shiga-like toxin I (SLT I), Shiga-like toxin II (SLT II), andE. coli O157 lipopolysaccharide (LPS). We tested serum samples from 83 patients in two outbreaks ofE. coli O157:H7 diarrhea and from 66 well persons. Forty-three patients (52%) had at least one serum sample positive for anti-O157 LPS antibodies; among 26 culture-confirmed patients, 24 (92%) had at least one positive serum sample. Two (3%) of 66 control sera had positive anti-O157 LPS titers. ELISA results for SLT I and II were compared with those of HeLa cell cytotoxicity neutralization assays on both patient and control sera. Neutralization assays detected anti-SLT I antibodies in at least one serum sample from each of 17 (20%) patients and 7 (10.6%) controls, while 16 (19%) patients and 7 controls had positive titers by anti-SLT I ELISA. Although all serum samples, including control sera, showed nonspecific neutralization of SLT II, no antibody titers to SLT II were detected by either neutralization or ELISA. These results indicate that ELISAs for SLT I and SLT II antibodies are comparable to HeLa cell cytotoxicity neutralization assays. Both the ELISAs and neutralization assays are insensitive in detecting infected patients. However, the ELISA for antibodies toE. coli O157 LPS is both sensitive and specific, and may be more useful than assays for antitoxic antibodies in detecting persons withE. coli O157:H7 infection. 相似文献
73.
74.
Adaptation of Phytoplankton-Degrading Microbial Communities to Thermal Reactor Effluent in a New Cooling Reservoir 下载免费PDF全文
Steven A. Schoenberg Ronald Benner Patricia Sobecky Robert E. Hodson 《Applied microbiology》1988,54(6):1481-1487
In water column and sediment inocula from a nuclear reactor cooling reservoir, natural phytoplankton substrate labeled with 14C was used to determine aerobic and anaerobic mineralization rates for a range of temperatures (25, 40, 55, and 70°C) expected during reactor operation. For experiments that were begun during reactor shutdown, aerobic decomposition occurred at temperatures of <55°C. After 2 months of reactor operation, aerobic rates increased substantially at 55 and 70°C, although maximum rates were observed at temperatures of ≤40°C. The temperature range for which maximum anaerobic mineralization (i.e., the sum of CH4 and CO2) was observed was 25 to 40°C when the reactor was off, expanding to 25 to 55°C during reactor operation. Increased rates at 55°C, but not 70°C, correlated with an increase in the ratio of cumulative methane to carbon dioxide produced over 21 days. When reduced reactor power lowered the maximum temperature of the reservoir to 42°C, aerobic decomposition at 70°C was negligible, but remained substantial at 55°C. Selection for thermophilic decomposers occurred rapidly in this system in both aerobic and anaerobic communities and did not require prolonged exposure to elevated temperatures. 相似文献
75.
Patricia Bedinger Eugenio L. de Hostos Patricia Leon Virginia Walbot 《Molecular & general genetics : MGG》1986,205(2):206-212
Summary A linear 2.3 kb DNA molecule found in maize mitochondria was cloned into pUC8. A natural deletion of this plasmid, found in cmsT and some N (fertile) types of maize plants, was mapped to one end of the plasmid. A minor sequence homology to S-2, another linear mitochondrial plasmid, was detected, as well as more significant sequence homology with chloroplast and maize nuclear DNA. Hybridization to teosinte mitochondrial DNA (mtDNA) revealed the presence of part of the maize plasmid in the high molecular weight mtDNA of the maize relatives. RNA dot hybridization indicates that the plasmid is transcribed in mitochondria. The termini of the 2.3 kb linear plasmid contain inverted repeated sequences; of the first 17 nucleotides of the termini, 16 are identical to the terminal inverted repeats of the linear S plasmids found in the mitochondria of cmsS maize plants. 相似文献
76.
Dr. Patricia Norris 《Applied psychophysiology and biofeedback》1986,11(1):1-20
This paper examines some of the philosophical and scientific relationships involving self-control, voluntary control, and psychophysiologic self-regulation. The role of biofeedback in mediating conscious and unconscious processes is explored. Demonstrations of superior voluntary control and its relationship to belief, confidence, and expectation are examined. Biofeedback demonstrates the potential of control to oneself, creating confidence in one's ability to establish enhanced and peak performance in athletics, education, and psychophysiologic therapy. Emphasis is placed on the power of images in all human functioning, and in enhancing human potential.Presidential address presented at the meetings of the Biofeedback Society of America, March 23, 1986, San Francisco. 相似文献
77.
78.
Patricia A. James F. Louise Lavender Gillian M. Lawrence Deryck G. Walker 《Biochemical genetics》1985,23(7-8):525-538
Partially purified preparations of the hepatic glucokinase from C3H/He and C58 inbred mice have been used to explore the molecular basis for the observed twofold difference in activity between the strains. The single codominant gene that appears to regulate activity, the alleles of which are designated Gka and Gkb, respectively, for the two strains, could represent a structural gene change. This now seems unlikely because the mouse enzyme, although showing small differences from rat glucokinase, appeared to be identical in the two strains with respect to thermal stability, electrophoretic mobility in agarose gels, and kinetic properties such as the apparent K
m values for MgATP2– and glucose and the unique cooperative interaction with the latter substrate. The enzymes also reacted identically in a range of immunological tests (double-diffusion, immunoelectrophoresis, immune precipitation and immune inhibition assays) and ELISA immune inhibition assays indicated that the twofold difference in activity was due to a similar difference in antigenically active enzyme. Genetic control over the physiologically significant regulation of enzyme amount is therefore probable.This work has been supported in part by a grant from the British Diabetic Association and a Training Studentship to PAJ from the Medical Research Council (U.K.). 相似文献
79.
Adaptation to High-Intensity, Low-Wavelength Light among Surface Blooms of the Cyanobacterium Microcystis aeruginosa 总被引:2,自引:0,他引:2 下载免费PDF全文
Hans W. Paerl Patricia T. Bland N. Dean Bowles Mark E. Haibach 《Applied microbiology》1985,49(5):1046-1052
Natural populations of the nuisance bloom cyanobacterium Microcystis aeruginosa obtained from the eutrophic Neuse River, N.C., revealed optimal chlorophyll a-normalized photosynthetic rates and resistance to photoinhibition at surface photosynthetically active radiation (PAR) intensities. At saturating PAR levels these populations exhibited higher photosynthetic rates in quartz than in Pyrex vessels. Eucaryotic algal populations obtained from the same river failed to counteract photoinhibition. At saturating PAR levels, such populations generally yielded lower photosynthetic rates in quartz containers than they did in Pyrex containers. Cultivation of natural Microcystis populations under laboratory conditions led to physiologically distinct populations which had photoinhibitory characteristics similar to those of other cultured cyanobacterial and eucaryotic algae. Our findings indicate that (i) photosynthetic production among natural surface populations is best characterized and quantified in quartz rather than Pyrex incubation vessels; (ii) extrapolation of natural photoinhibitory trends from laboratory populations is highly subjective to culture and PAR histories and may yield contradictory results; and (iii) buoyant surface-dwelling populations, rather than exhibiting senescence, are poised at optimizing PAR utilization, thereby maintaining numerical dominance in eutrophic waters when physico-chemical conditions favor bloom formation. 相似文献
80.
Patricia C. Weber F.R. Salemme Spencer H. Lin Yasuo Konishi H.A. Scheraga 《Journal of molecular biology》1985,181(3):453
A cross-linked derivative of ribonuclease A, Nε,Nε′-(2,4-dinitrophenylene-1,5)-(lysine7-lysine41)-RNase A, has been crystallized by dialysis against 30% () ethanol/water mixtures buffered at high pH. Single crystals belong to the orthorhombic space group P212121, , with one molecule in the Crystallographic asymmetric unit. 相似文献