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41.
An Improved Diluent for Rubella Hemagglutination and Hemagglutination-Inhibition Tests 总被引:3,自引:2,他引:1 下载免费PDF全文
Angela E. Auletta Gary L. Gitnick Carrie E. Whitmire John L. Sever 《Applied microbiology》1968,16(5):691-694
Rubella hemagglutinating (HA) antigen was prepared in BHK-21 tissue as 5% cell suspensions and from unconcentrated and 20× concentrated infected supernatant fluids. In some instances, unconcentrated fluids were treated with Tween 80 and ether; cell suspensions were treated with ether alone. Preparations were tested for HA activity in dextrose-gelatin-Veronal (DGV) buffer solutions; 0.85% NaCl; Sorenson's phosphate-buffered saline, pH 7.2; and a diluent of 0.9% NaCl, 0.1% CaCl2 (anhydrous), and 0.1% MgSO4·7H2O. HA titers were consistently two- to fourfold higher in the saline with added Ca++ and Mg++ than in DGV. Hemagglutination-inhibition titers of paired human sera were the same in either diluent. It is suggested that the interaction between rubella HA antigen and the red cells of young (less than 1-day-old) chicks may be at least partially ion dependent and that titers are enhanced by increased quantities of divalent cations. 相似文献
42.
Characterization of a Nerve Growth Factor-Stimulated Protein Kinase in PC12 Cells Which Phosphorylates Microtubule-Associated Protein 2 and pp250 总被引:15,自引:5,他引:10
Gary E. Landreth Deanna S. Smith Craig McCabe Cynthia Gittinger 《Journal of neurochemistry》1990,55(2):514-523
Treatment of PC12 cells with nerve growth factor (NGF) resulted in the rapid, but transient, activation of a protein kinase which specifically phosphorylated an endogenous 250-kDa cytoskeletal protein (pp250). We report that the microtubule-associated protein, MAP2, is an alternative substrate for the NGF-activated kinase. NGF treatment maximally activated the kinase within 5 min; however, the activity declined with longer exposure to NGF. The enzyme was localized predominantly in microsomal and soluble fractions and phosphorylated MAP2 on serine and threonine residues. The soluble enzyme was fractionated by DEAE chromatography and gel filtration and had an apparent Mr of 45,000. The enzyme was purified to near homogeneity by chromatofocussing and had a pI of 4.9. Kinetic analysis revealed that NGF treatment caused a sevenfold increase in Vmax for MAP2. The Km with respect to the MAP2 substrate was approximately 50 nM and was not altered by NGF treatment. A novel feature of the NGF-stimulated enzyme was its sharp dependence on Mn2+ concentration. The active enzyme is likely to be phosphorylated, because inclusion of phosphatase inhibitors was required for recovery of optimal activity and the activity was lost on treatment of the enzyme with alkaline phosphatase. Histones, tubulin, casein, bovine serum albumin, and the ribosomal subunit protein S-6 were not phosphorylated by this enzyme. The NGF-stimulated kinase was distinct from A kinase, C kinase, or other NGF-stimulated kinases. The rapid and transient activation of the protein kinase upon NGF treatment suggests that the enzyme may play a role in signal transduction in PC12 cells. 相似文献
43.
Gary Gibson Pamela Nielsen Victoria Mykytyn Ken Carlson John Blass 《Neurochemical research》1989,14(1):17-24
To further elucidate the molecular basis of the selective damage to various brain regions by thiamin deficiency, changes in enzymatic activities were compared to carbohydrate flux through various pathways from vulnerable (mammillary bodies and inferior colliculi) and nonvulnerable (cochlear nuclei) regions after 11 or 14 days of pyrithiamin-induced thiamin deficiency. After 11 days,large decreases (–43 to –59%) in transketolase (TK) occurred in all 3 regions; 2-ketoglutarate dehydrogenase (KGDHC) declined (–45%), but only in mammillary bodies; pyruvate dehydrogenase (PDHC) was unaffected. By day 14, TK remained reduced by 58%–66%; KGDHC was now reduced in all regions (–48 to –55%); PDHC was also reduced (–32%), but only in the mammillary bodies. Thus, the enzyme changes did not parallel the pathological vulnerability of these regions to thiamin deficiency.14CO2 production from14C-glucose labeled in various positions was utilized to assess metabolic flux. After 14 days, CO2 production in the vulnerable regions declined severely (–46 to 70%) and approximately twice as much as those in the cochlear nucleus. Also by day 14, the ratio of enzymatic activity to metabolic flux increased as much as 56% in the vulnerable regions, but decreased 18 to 30% in the cochlear nuclei. These differences reflect a greater decrease in flux than enzyme activities in the two vulnerable regions. Thus, selective cellular responses to thiamin deficiency can be demonstrated ex vivo, and these changes can be directly related to alterations in metabolic flux. Since they cannot be related to enzymatic alterations in the three regions, factors other than decreases in the activity of these TPP-dependent enzymes must underlie selective vulnerability in this model of thiamin deficiency.Abbreviations KGDHC
2-ketoglutarate dehydrogenase complex EC 1.2.4.2., EC 2.3.1.61, EC 1.6.4.3.
- PDHC
pyruvate dehydrogenase complex EC 1.2.4.2., EC 2.3.1.12, EC 1.6.4.3
- TK
transketolase (EC 2.2.1.1)
- TPP
thiamin pyrophosphate 相似文献
44.
Molecular and functional analysis of the ruv region of Escherichia coli K-12 reveals three genes involved in DNA repair and recombination 总被引:14,自引:0,他引:14
Gary J. Sharples Fiona E. Benson Graham T. Illing Robert G. Lloyd 《Molecular & general genetics : MGG》1990,221(2):219-226
Summary Recombinant plasmids carrying ruvA, ruvB, or both were constructed and used to investigate the genetic defects in a collection of UV-sensitive ruv mutants. The results revealed that efficient survival of UV-irradiated cells depends on both ruvA and ruvB, and on a third gene, ruvC, located upstream of the ruvAB operon. Southern blotting analysis was used to locate insertions in ruv and to examine putative deletion mutants. Two Tn10 insertions were located to the region encoding ruvA. Since these insertions caused a deficiency in the activities of both ruvA and ruvB, we concluded that they must exert a polar effect on ruvB. Two putative ruv deletion mutants were shown to be the result of deletion-inversion events mediated during imprecise excision of Tn10. The relevant inversion breakpoints in these mutants were located to ruvA and ruvC. 相似文献
45.
Catabolic plasmids of environmental and ecological significance 总被引:13,自引:0,他引:13
The environmental and ecological significance of catabolic plasmids and their host strains are discussed in the context of their potential application for environmental biotechnology. Included is a comprehensive list of naturally occurring discrete catabolic plasmids isolated from either natural habitats or selective enrichment studies. General properties, such as plasmid maintenance, stability and transfer, are discussed together with the techniques for plasmid detection and monitoring in the environment. The issues concerning the construction of catabolic strains with new or broader substrate ranges and the uses of monocultures or consortia for in situ treatment are addressed. 相似文献
46.
Ian T. Forrester Anthony C. Grabski Chittra Mishra Brian D. Kelley W. Nick Strickland Gary F. Leatham Richard R. Burgess 《Applied microbiology and biotechnology》1990,33(3):359-365
Summary Extracellular culture filtrates from ligninolytic cultures of the lignin-degrading basidiomycete Lentinula (syn. Lentinus) edodes (Berk.) Pegler contained one major peroxidase when grown on a commercial oak-wood substrate. The peroxidase was purified by polyethylenimine clarification, anion-exchange chromatography, and hydrophobic-interaction HPLC. The enzyme (MnP1) was a heme-iron protein with an apparent molecular weight of 44 600 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels and an isoelectric point of pH 3.2. The native enzyme had an absorption maximum at 407 nm, which shifted to 420 nm upon H2O2 addition. The pyridine-hemochrome-absorption spectrum indicated that one heme group was present per enzyme as protoporphyrin IX. N-terminal amino acid sequencing showed that MnP1 had higher sequence homology with manganese peroxidases than with lignin peroxidases reported from Phanerochaete chrysosporium. L. edodes MnP1 was capable of oxidizing lignin and lignin-model compounds in the presence of manganese and H2O2.On leave from the Department of Biochemistry, University of Otago, P. O. Box 56, Dunedin, New Zealand.Research carried out while a visiting scientist at the USDA Forest Products Laboratory from the National Chemistry Laboratory, Pune, India 41 1008
Offprint requests to: I. T. Forrester 相似文献
47.
A stress-muscle hyperactivity-pain (SMP) model has been proposed to explain the etiology of certain musculoskeletal pain disorders. According to this model, subjects should show physiological arousal during periods of stress relative to periods of rest. In a test of this prediction, 31 subjects performed a reaction time task that has been used in previous laboratory studies. Multiple psychophysiological variables were monitored during initial and final 10-minute baselines, during performance on nine 2-minute reaction time tasks, and during 36-second rest intervals following each of the 2-minute tasks. Results showed small but statistically significant differences generally supporting the SMP model when masseter EMG was averaged over time periods of 12 seconds to 2 minutes, but not when masseter EMG was averaged over 10- to 18-minute blocks. These results demonstrated the importance of carefully selecting time intervals for analysis. Additional analyses that compared TMD with symptom-free subjects revealed small differences in EMG that supported the SMP model. Analyses of EMG over shorter time intervals also showed, however, that masseter EMG increased during the 36-second rest interval following performance on a 2-minute stress task; this result suggested that a modification of the SMP model may be necessary.This research was supported in part by Grant 2 S06RR08038-17 funded by the National Institutes of Health. 相似文献
48.
Joyce Greene Mark Rosenbach Gary Darland 《Journal of industrial microbiology & biotechnology》1990,5(5):313-321
Summary Selection of spontaneous mutants ofNocardia lactamdurans MA2908 for resistance to 5-fluorouracil results in the simultaneous development of resistance to 5-fluorouridine. The resulting mutants fall into four distinct classes based on the amount of uracil accumulating in fermentation broths. An additional characteristic of these mutants is a reduction in the ability to incorporate exogenous uracil into nucleic acids even though transport and conversion to the nucleotide level appears normal. Finally, production of efrotomycin is increased in these mutants in both chemically defined and complex fermentation media to levels equivalent to those of MA4820, the first productivity mutant isolated in a conventional strain improvement program. Resistance development and uracil excretion are adequately explained by an elevation of the intracellular uridine nucleotide pool, in particular UMP. The role of the uridine necleotides in the efrotomycin fermentation is unknown. 相似文献
49.
Identification of consensus patterns in unaligned DNA sequences known to be functionally related 总被引:16,自引:0,他引:16
Hertz Gerald Z.; Hartzell George W. III; Stormo Gary D. 《Bioinformatics (Oxford, England)》1990,6(2):81-92
We have developed a method for identifying consensus patternsin a set of unaligned DNA sequences known to bind a common proteinor to have some other common biochemical function. The methodis based on a tnatrix representation of binding site patterns.Each row of the matrix represents one of the four possible bases,each column represents one of the positions of the binding siteand each element is determined by the frequency the indicatedbase occurs at the indicated position. The goal of the methodis to find the most significant matrix-i.e. the one with thelowest probability of occurring by chance-out of all the matricesthat can be formed from the set of related sequences. The reliabilityof the method improves with the number of sequences, while thetime required increases only linearly with the number of sequences.To test this method, we analysed 11 DNA sequences containingpromoters regulated by the Escherichia coli LexA protein. Thematrices we' found were consistent with the known consensussequence, and could distinguish the generally accepted LexAbinding sites from other DNA sequences.
Received on November 6, 1989; accepted on December 20, 1989 相似文献
50.
Mutants of Arabidopsis thaliana L. (Heynh), characterized asdeficient in their freezing tolerance after cold acclimation,were surveyed for some of the normal responses to cold exposure.In foliar tissue, the coldinducibility of three proteins, thelevels of sucrose and glucose, the fatty acyl composition oflipids, and the accumulation of anthocyanin was examined. Fourmutations (sfr3, sfr4, sfr6, and sfr7) reduced or eliminatedthe accumulation of anthocyanin during cold acclimation. Onemutation (sfr4) prevented the normally cold-induced elevationof sucrose and glucose levels; both sfr4 and another mutation(sfr7) affected fatty acid composition after (and only after)cold acclimation. On the other hand mutations sfr1, sfr2 andsfr5 did not differ significantly from the wild type in anyof the parameters tested, suggesting that they have other, perhapshighly specific, effects on lowtemperature responses. Key words: Arabidopsis thaliana, cold acclimation, freezing tolerance, mutation 相似文献