Two classes of alkaline phosphatase constitutive mutations which comprise the original phoS locus (genes phoS and phoT ) on the Escherichia coli genome have been implicated in the regulation of alkaline phosphatase synthesis. When these mutations were introduced into a strain dependent on a single system, the pst system, for inorganic phosphate (P i ) transport, profound changes in P i transport were observed. The phoT mutations led to a complete P i − phenotype in this background, and no activity of the pst system could be detected. The introduction of the phoS mutations changed the specificity of the pst system so that arsenate became growth inhibitory. Changes in the phosphate source led to changes in the levels of constitutive alkaline phosphatase synthesis found in phoS and phoT mutants. When glucose-6-phosphate or l -α-glycerophosphate was supplied as the sole source of phosphate, phoT mutants showed a 3- to 15- fold reduction in constitutive alkaline phosphatase synthesis when compared to the maximal levels found in limiting P i media. However, these levels were still 100 times greater than the basal level of alkaline phosphatase synthesized in wild-type strains under these conditions. The phoS mutants showed only a two- to threefold reduction when grown with organic phosphate sources. The properties of the phoT mutants selected on the basis of constitutive alkaline phosphatase synthesis were similar in many respects to those of pst mutants selected for resistance to growth inhibition caused by arsenate. It is suggested that the phoS and phoT genes are primarily involved in P i transport and, as a result of this function, play a role in the regulation of alkaline phosphatase synthesis.
Objectives The goal of this study is to describe modifiable lifestyle variables associated with reduced rate of Parkinson's disease (PD) progression. Methods The patient-reported outcomes in PD (PRO-PD) were used as the primary outcome measure, and a food frequency questionnaire (FFQ) was used to assess dietary intake. In this cross-sectional analysis, regression analysis was performed on baseline data to identify the nutritional and pharmacological interventions associated with the rate of PD progression. All analyses were adjusted for age, gender, and years since diagnosis. Results 1053 individuals with self-reported idiopathic PD were available for analysis. Foods associated with the reduced rate of PD progression included fresh vegetables, fresh fruit, nuts and seeds, nonfried fish, olive oil, wine, coconut oil, fresh herbs, and spices (P < 0.05). Foods associated with more rapid PD progression include canned fruits and vegetables, diet and nondiet soda, fried foods, beef, ice cream, yogurt, and cheese (P < 0.05). Nutritional supplements coenzyme Q10 and fish oil were associated with reduced PD progression (P = 0.026 and P = 0.019, resp.), and iron supplementation was associated with faster progression (P = 0.022). Discussion These are the first data to provide evidence that targeted nutrition is associated with the rate of PD progression.
Two hih-affinity iron uptake systems are known in Salmonella typhunurinum, one utiig iron-enteohelin and the other uliing ferichrome. It has been shown previously that expreon of several element of the iron-enterochelin uptake system are ated by the iron content of the medium, with growth in high-iron medium resulting in repon of enzymes of enterochelin synthsis and degradation and of the ability of whole cels to take up iron-enterochelin In this study we describe a mutant strain in which growth in high-iron medium was assciated with constitutive exreon of. (i) iron-enterochelin uptake by whole cells (ii) ferirome uptake by whole cells; (iii) synthesis of enterochelin; (iv) itracellular degradation of iron-enterochelin; and (v) synthesis of three major outer-membe prot (OM1, OM2, and OM3). In conbwtr in the wildtype strain the4s prorties were only after growth in iron-deficient medium. It is proposed that the mutation ffects a gene responsible for regulating expssion of the structual genes for the components of the high-affinity iron uptake ystems. The term fur, for iron (Fe) uptake regulation, is suggetd for this new class of mutant. Several high-affinity systems are known to perticipate in iron uptake in SabnoneUa typhimurinum and Ewcherichia coli. The enterochelin uptake system facilitates entry of iron complexed to enterochelin, a cyclic trimer of 2,3dihydroxybenzoylserine syntheized and excreted by the bacterium itself. This presumably represents the physiologically relevant system under most circunutances (3, 31). The fernchrome uptake system facilitates entry of iron complexed to siderophores produced by fimgi (3, 19, 23). A third high-affinity uptake systm facilitats entry ofiron-citrate complexes in E. coli but is not present in S. typhimurium (8, 32).
We have measured the microsecond rotational motions of myosin heads in contracting rabbit psoas muscle fibers by detecting the transient phosphorescence anisotropy of eosin-5-maleimide attached specifically to the myosin head. Experiments were performed on small bundles (10-20 fibers) of glycerinated rabbit psoas muscle fibers at 4 degrees C. The isometric tension and physiological ATPase activity of activated fibers were unaffected by labeling 60-80% of the heads. Following excitation of the probes by a 10-ns laser pulse polarized parallel to the fiber axis, the time-resolved emission anisotropy of muscle fibers in rigor (no ATP) showed no decay from 1 microsecond to 1 ms (r infinity = 0.095), indicating that all heads are rigidly attached to actin on this time scale. In relaxation (5 mM MgATP but no Ca2+), the anisotropy decayed substantially over the microsecond time range, from an initial anisotropy (r0) of 0.066 to a final anisotropy (r infinity) of 0.034, indicating large-amplitude rotational motions with correlation times of about 10 and 150 microseconds and an overall angular range of 40-50 degrees. In isometric contraction (MgATP plus saturating Ca2+), the amplitude of the anisotropy decay (and thus the amplitude of the microsecond motion) is slightly less than in relaxation, and the rotational correlation times are about twice as long, indicating slower motions than those observed in relaxation. While the residual anisotropy (at 1 ms) in contraction is much closer to that in relaxation than in rigor, the initial anisotropy (at 1 microsecond) is approximately equidistant between those of rigor and relaxation.(ABSTRACT TRUNCATED AT 250 WORDS)
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