Characteristics of secondary cytotoxic T-cell responses in mice infected with influenza A viruses.

The cytotoxic T-cell response in mice infected with type A influenza viruses is dominated by a highly cross-reactive component. Previous experiments showed that after primary immunization the cytotoxic T-cell response apparently consists of a small but significant portion which is specific for the immunizing virus, and a larger component which is highly cross-reactive among all A strain viruses. The present study concentrates on the specificity of the T-cell response after secondary stimulation, using various combinations of type A virus strains. The underlying rationale was to determine whether there was any discernable pattern in the T-cell response which parallels the serologically defined antigenic pattern of influenza.That a virus strain-specific set of precursors does exist was evident in the primary response and even more so upon secondary challenge with the homologous virus (using an adoptive transfer protocol). However, upon secondary challenge with a heterologous influenza virus, this specific component was not evident no matter how closely related serologically the two challenge viruses were. No obvious relationships could be found between serologically defined antigenic patterns and the capacity to stimulate a secondary T-cell response specific for a particular type A influenza virus.     

Pyrroline-5-carboxylic acid reductase from soybean leaves

Pyrroline-5-carboxylic acid reductase was purified 40-fold from soybean leaves (Glycine max L. var Corsoy). The enzyme was fairly unstable, had a broad pH optimum, and was inactivated by heat and acid; NADH and NADPH both served as cofactors. It had a higher activity with NADH (about 4 ×) compared to NADPH, but a lower K_m for NADPH. NADP⁺ inhibited both the NADH- and NADPH-dependent activity. Sulfhydryl group blocking agents reduced the activity as did the carbonyl blocking agent, NH₂OH. Thiazolidine-4-carboxylic acid and phosphate inhibited the enzyme and proline inhibited only at high concentrations. ATP, GTP, and CTP were all effective inhibitors of both the NADH- and NADPH-dependent activity. Phosphorylated nucleotide inhibition was reversed by Mg²⁺ ions.     

Photoreduction of sulfur dioxide by spinach leaves and isolated spinach chloroplasts

Labeled sulfur dioxide was found to be extensively absorbed by spinach (Spinacea oleracea L.) leaves. Labeled sulfides detected in leaf blades following fumigations with sulfur dioxide in light indicated that photoreduction of sulfur dioxide had occurred. Measurable proportions of this labeled sulfur was localized within the chloroplast fraction. Suspensions of isolated chloroplasts supplied with labeled sulfur dioxide contained labeled sulfides following a 30-minute illumination period in water-cooled reaction vessels. With reference to recent studies of the chloroplast sulfur reduction pathway, probable points of entry for sulfur dioxide and the subsequent release of hydrogen sulfide are discussed.     

Whole-cell and membrane lipids of the methylotrophic bacterium Methylosinus trichosporium.

The lipid composition of the methylotrophic bacterium Methylosinus trichosporium was examined. Whole-cell lipid distribution was 39.1% neutral lipids, 34.5% polar lipids, and 26.4% poly-beta-hydroxybutyric acid. Membrane lipids were 83% phospholipids, with phosphatidylethanolamine and phosphatidylglycerol accounting for over 94% of the total. All the phospholipids had similar fatty acid compositions, with 18:1 accounting for about 87% of the total and most of the rest consisting of 16:1. Similarities between the lipid composition of this bacterium and other bacteria are discussed.     

Exercise increases the release of NAMPT in extracellular vesicles and alters NAD + activity in recipient cells

Aging is associated with a loss of metabolic homeostasis, with cofactors such as nicotinamide adenine dinucleotide (NAD⁺) declining over time. The decrease in NAD⁺ production has been linked to the age‐related loss of circulating extracellular nicotinamide phosphoribosyltransferase (eNAMPT), the rate‐limiting enzyme in the NAD⁺ biosynthetic pathway. eNAMPT is found almost exclusively in extracellular vesicles (EVs), providing a mechanism for the distribution of the enzyme in different tissues. Currently, the physiological cause for the release of eNAMPT is unknown, and how it may be affected by age and physical exercise. Here, we show that release of small EVs into the bloodstream is stimulated following moderate intensity exercise in humans. Exercise also increased the eNAMPT content in EVs, most prominently in young individuals with higher aerobic fitness. Both mature fit and young unfit individuals exhibited a limited increase in EV‐eNAMPT release following exercise, indicating that this mechanism is related to both the age and physical fitness of a person. Notably, unfit mature individuals were unable to increase the release of eNAMPT in EVs after exercise, suggesting that lower fitness levels and aging attenuate this important signalling mechanism in the body. EVs isolated from exercising humans containing eNAMPT were able to alter the abundance of NAD⁺ and SIRT1 activity in recipient cells compared to pre‐exercise EVs, indicating a pathway for inter‐tissue signalling promoted through exercise. Our results suggest a mechanism to limit age‐related NAD⁺ decline, through the systemic delivery of eNAMPT via EVs released during exercise.     

Cell specific expression of three genes involved in plasma membrane sucrose transport in developingVicia faba seed

Summary In developing seeds ofVicia faba, transfer cells line the inner surface of the seed coat and the juxtaposed epidermal surface of the cotyledons. Circumstantial evidence, derived from anatomical and physiological studies, indicates that these cells are the likely sites of sucrose efflux to, and influx from, the seed apoplasm, respectively. In this study, expression of an H⁺/sucrose symporter-gene was found to be localised to the epidermal-transfer cell complexes of the cotyledons. The sucrose binding protein (SBP) gene was expressed in these cells as well as in the thin-walled parenchyma transfer cells of the seed coat. SBP was immunolocalised exclusively to the plasma membranes located in the wall ingrowth regions of the transfer cells. In addition, a plasma membrane H⁺-ATPase was most abundant in the wall ingrowth regions with decreasing levels of expression at increasing distance from the transfer cell layers. The observed co-localisation of high densities of a plasma membrane H⁺-ATPase and sucrose transport proteins to the wall ingrowths of the seed coat and cotyledon transfer cells provides strong evidence that these regions are the principal sites of facilitated membrane transport of sucrose to and from the seed apoplasm.Abbreviations BCIP 5-bromo-4-chloro-3-indolyl phosphate - DIG digoxigenin - H⁺-ATPase plasma membrane H⁺-translocating adenosine triphosphatase - Ig immunoglobulin - LeSUT1 tomato H⁺/sucrose symporter - SBP sucrose binding protein     

Isolation of kappa-carrageenan oligosaccharides using ion-pair liquid chromatography--characterisation by electrospray ionisation mass spectrometry in positive-ion mode

Oligo-kappa-carrageenans participate as elicitors in the cell-cell recognition process in marine plants. Analytical methods can be usefully applied to gain insight into the biochemistry of these biological processes. Therefore, enzymatically digested oligomers of kappa-carrageenans have been separated and isolated on a Spherisorb ODS1 (250 x 4 mm i.d., particle size 5 microm) column using ion-pair liquid chromatography coupled with an evaporative light scattering detector. Heptylamine (5 mM, pH4) has been selected as the ion-pairing agent and MeOH as the organic modifier in a gradient mode. Overloading the column with 1mg of the mixture, the chromatographic mechanism presented adequate stability. The mobile phase of each isolated oligomer was evaporated and the residue was infused into an electrospray ionisation mass spectrometry (ESIMS) in positive-ion mode with 4:1 MeCN-water as mobile phase. Each ESIMS spectrum presented ions consisting of the oligomer attached with a number of heptylammonium ions depending on the molecule size. In addition, the different m/z values permitted direct detection of the oligomers in ESIMS positive-ion mode. The analytical method developed separated the oligomers up to dotriacontasaccharide.     

Reconfiguration of a Multi-oscillator Network by Light in the Drosophila Circadian Clock

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Heterocyclic ketones as inhibitors of histone deacetylase

Several heterocyclic ketones were investigated as potential inhibitors of histone deacetylase. Nanomolar inhibitors such as 22 and 25 were obtained, the anti-proliferative activity of which were shown to be mediated by HDAC inhibition.