Evidence for generation of a large amount of nitric oxide-like vascular smooth muscle relaxant by cholesterol-rich neutrophils

To determine the effect of cholesterol incorporation on the ability of neutrophils to generate superoxide radicals and nitric oxide-like vasorelaxant material, isolated human neutrophils were incubated with cholesterol-rich liposomes, which increased total cholesterol content by 141% and esterified cholesterol content by 523%. Cholesterol loading resulted in 5 to 7 fold increase in cytosolic calcium in resting as well as in PMA or f-MLP-stimulated cells, but a marked (P less than 0.01) reduction in both PMA- and f-MLP-stimulated superoxide radical generation by these cells. Nitric oxide-like activity measured as relaxation of rat aortic rings was more pronounced (P less than 0.02) in cholesterol-rich than in cholesterol-poor cells. The greater relaxation of aortic rings in response to cholesterol-rich neutrophils was observed in rings with or without intact endothelium, and was potentiated by superoxide dismutase and inhibited by oxyhemoglobin as well as L-NMMA, thus suggesting that the vasorelaxant material was nitric oxide. The greater generation of nitric oxide by cholesterol-rich neutrophils occurs perhaps in response to increased cytosolic calcium.     

Developmental anomalies derived from exposure of zygotes and first-cleavage embryos to mutagens.

Results of continuing studies indicate that the mouse zygote and two-cell embryo stages are a window of susceptibility in the experimental induction of congenital anomalies with certain mutagenic agents. The mechanisms by which the mutagens initiate the pathogenesis of these developmental defects are not known. However, in certain cases there is evidence that a nonconventional, perhaps epigenetic, mechanism is involved. Detailed characterization of the spectrum of anomalies induced and comparison of responses at the various stages exposed allowed classification of the mutagens generally into two groups. One group is characterized by being effective only in the early stages of zygote development and capable of producing a relatively high incidence of fetal death and hydrops. The other group affects all of the zygote stages studied as well as the two cell-embryo, but does not increase the incidence of fetal death and hydrops. Except for hydrops, chemicals in the two groups do not differ in terms of the types of anomalies present among malformed live fetuses, which bear a resemblance to a subset of common, sporadic human developmental anomalies that are of unknown etiology. This similarity raises the possibility that certain human developmental defects may have their origins in events that happen in the zygote and early pre-implantation stages.     

Anthranilic acid metabolism by microorganisms. Formation of 5-hydroxyanthranilate as an intermediate in anthranilate metabolism byNocardia opaca

5-Hydroxyanthranilic acid was isolated and characterized as an intermediate in the metabolism of anthranilate byNocardia opaca. This compound appeared during the log phase of growth and led to the subsequent induction of high levels of enzymes for its subsequent degradation. Gentisate was also found as a product of 5-hydroxyanthranilate metabolism. Both 5-hydroxyanthranilate and gentisate were oxidized to pyruvate by extracts of anthranilate-grown cells, the ring cleavage of the diphenol being effected by an oxygenase with a typical Fe²⁺ requirement. Features of the metabolism of 5-hydroxyanthranilate and gentisate byN. opaca, which can also oxidize anthranilate through catechol, suggest that the gentisate pathway is a secondary route.     

DNA typing of grapevines: A universal methodology and database for describing cultivars and evaluating genetic relatedness

With established ampelographic techniques for grapevine identification it is often difficult to achieve a satisfactory, objective result. We have developed a DNA typing system using sequence-tagged microsatellite site markers as a means of differentiating cultivars of grapevine. A semi-automated analysis procedure was linked to an electronic database and found to be an objective and reliable system for cultivar identification using this simple marker type. The accumulated DNA typing data from over eighty cultivars demonstrated that cultivars that are difficult to differentiate phenotypically using ampelographic techniques can be distinguished by DNA typing. Parentage analysis uncovered errors in parent assignment of cultivar identification in specific cases. The electronic database has a conservative format to take into account the occurrence of null alleles and the possibility of missed alleles. Computer-assisted comparisons of cultivars in the database can be performed and various approaches for estimating the match probability that two unrelated cultivars have the same genotype simply due to chance are discused. We suggest that further development of the database through international co-operation using standardised sequence-tagged site markers offers the possibility of achieving a universal grapevine identification system.     

Detection thresholds for an olfactory mixture and its three constituent compounds

Single sub-threshold odorants can, according to a few reports,become perceptible in concert. That is, they can exhibit mixtureadditivity. The present study measured thresholds for mixtureof 1-butanol, 2-pentanone, and n-butyl acetate, and for eachof these separately. ‘Complete’ additivity resulted,in that the threshold concentration of each compound in themixture (measured by gas chromatography) turned out to be one-thirdof each component separately. Earlier threshold studies alsoclaimed complete additivity and even hyper-additivity (synergism);in this regard they, like this study, differ from the more numerousstudies of suprathreshold mixtures, which yield imperfect additivity(hypo-additivity). Mixtures not only enhance sensitivity, butthey may also promote stability; intersubject variability wassmaller for the mixture than for the components. Subjects were20 young (18–26 years) and 20 elderly (69–91 years)persons, who gave two sets of thresholds on 2 days. Concordantwith earlier findings, the elderly's thresholds averaged higher(     

The mTOR regulated RNA-binding protein LARP1 requires PABPC1 for guided mRNA interaction

The mammalian target of rapamycin (mTOR) is a critical regulator of cell growth, integrating multiple signalling cues and pathways. Key among the downstream activities of mTOR is the control of the protein synthesis machinery. This is achieved, in part, via the co-ordinated regulation of mRNAs that contain a terminal oligopyrimidine tract (TOP) at their 5′ends, although the mechanisms by which this occurs downstream of mTOR signalling are still unclear. We used RNA-binding protein (RBP) capture to identify changes in the protein-RNA interaction landscape following mTOR inhibition. Upon mTOR inhibition, the binding of LARP1 to a number of mRNAs, including TOP-containing mRNAs, increased. Importantly, non-TOP-containing mRNAs bound by LARP1 are in a translationally-repressed state, even under control conditions. The mRNA interactome of the LARP1-associated protein PABPC1 was found to have a high degree of overlap with that of LARP1 and our data show that PABPC1 is required for the association of LARP1 with its specific mRNA targets. Finally, we demonstrate that mRNAs, including those encoding proteins critical for cell growth and survival, are translationally repressed when bound by both LARP1 and PABPC1.     

The role of aortic chemoreceptors during acute anemia

The importance of aortic chemoreceptors in the circulatory and metabolic responses during acute anemia was studied in anesthetized dogs. Data were obtained from nine dogs in which the aortic chemoreceptors were surgically denervated prior to induction of anemia, and from seven sham-operated dogs. Cardiac output (QT), limb blood flow (QL), limb and whole body oxygen uptake (VO2) were determined at normal hematocrit (Hct) and at 30 min of anemia (Hct = 13%) produced by isovolemic dextran-for-blood exchange. At 30 min of anemia, QT was increased from 91 to 186 mL . kg-1 . min-1 (p less than 0.01) and from 99 to 153 mL . kg-1 . min-1 (p less than 0.01) in the sham and denervated groups, respectively. The increase in QT during anemia was less (p less than 0.05) in the aortic-denervated series. Limb flow was also increased during anemia in both groups (p less than 0.01); the mean value of 89 mL . kg-1 . min-1 in the denervated group was less than that of 130 mL . kg-1 . min-1 observed in the sham animals (p less than 0.05). Whole body VO2 decreased (p less than 0.05) in the denervated group at 30 min of anemia; limb VO2 was maintained at the preanemic control value in both groups. The data indicate that during acute anemia the aortic chemoreceptors contribute to the increase in QT.     

ALGAL COMPETITION IN AN EPILITHIC RIVER FLORA1

Field and laboratory procedures demonstrate that the effluent from the Willimantic, Connecticut, sewage treatment plant changes the numerical composition of the dominant epilithic algae in the Shetucket River. This effect is due to the effluent altering the competitive balance between chlorella sp. and Achnanthes deflexa Reim. The chlorella completely dominates highly polluted stretches of the river, and shares dominance with A. deflexa in other areas. The degree of river pollution can be estimated by enumerating the natural standing crops of these 2 algae. A 2-membered assay utilizing these organisms is a sensitive laboratory pollution monitor and a useful predictive tool. Dominant stands of these epilithic species develop in polluted and unpolluted zones in this river due to competition for the limited area on the cobbles.