Effect of cycloheximide on tryptophan binding to rat hepatic nuclei

Summary. This study evaluated whether cycloheximide, an inhibitor of protein synthesis, would affect the binding of L-tryptophan to rat hepatic nuclei or nuclear envelopes. Previous reports have indicated that the binding of L-tryptophan to hepatic nuclear envelope protein was saturable, stereospecific, and of high affinity. Also, the administration of L-tryptophan rapidly stimulated hepatic protein synthesis. In this study, we determined that the addition of cycloheximide in vitro inhibited ³H-tryptophan binding to hepatic nuclei or nuclear envelopes. Heat-treated cycloheximide failed to have this inhibitory binding effect. In vivo treatment of rats with cycloheximide diminished in vitro ³H-tryptophan binding to hepatic nuclei of treated rats compared to controls. Puromycin, another inhibitor of hepatic protein synthesis, when added in vitro did not affect ³H-tryptophan binding to hepatic nuclei but did diminish in vitro binding after in vivo treatment. Thus, cycloheximide added in vitro diminished ³H-tryptophan binding to hepatic nuclei probably by its structural effect on the receptor while cycloheximide administered in vivo may also act in part by inhibiting protein synthesis. Received March 22, 1999, Accepted May 31, 1999     

Effect of Micronutrients on Methylglyoxal-Mediated In Vitro Glycation of Albumin

Nonenzymatic glycation of long-lived proteins has been implicated in several complications related to age and diabetes. Dicarbonyl compounds such as methylglyoxal (MGO) have been identified as the predominant source for the formation of advanced glycation end-products (AGEs) in various tissues. We investigated the effect of 13 micronutrients on MGO-mediated in vitro glycation of bovine serum albumin (BSA), as formation of AGEs and protein carbonyls. BSA (10 mg/ml) was incubated at 37°C with 100 mM MGO for 24 hours, in presence of ascorbic acid, Trolox (water-soluble α-tocopherol analog), β-carotene, retinol, riboflavin, thiamin, folic acid, niacin, pyridoxine, zinc, iron, manganese, and selenium. Fluorescence was measured at the wavelength pair of 370 and 440 nm as an index of the formation of AGEs and spectra were recorded for promising interactions at λex = 280 nm and λex = 370 nm. Within four standard antiglycating agents, aminoguanidine showed highest inhibitory response for BSA glycation followed by quercetin, gallic acid, and tannic acid. Promising antiglycation potential was seen for Trolox, riboflavin, Zn, and Mn as evidenced by decrease in the formation of AGEs and protein carbonyls.     

Effect of natural b-carotene supplementation in children exposed to radiation from the Chernobyl accident

Attempts were made to evaluate 709 children (324 boys and 385 girls) who had been exposed long-term to different doses of radiation during and after the Chernobyl accident and had moved to Israel between 1990 and 1994. Upon arrival, all of them underwent a check-up for most common clinical disorders and were then divided into three groups according to their residences (distance from the reactor) and the level of irradiation exposure: no radiation, <5 Ci/m², and >5 Ci/m², respectively. Blood serum analyses for total carotenoids, retinol, α-tocopherol and oxidized conjugated dienes in 262 of the children showed increased HPLC levels of conjugated dienes, indicating increased levels of oxidation of in vivo blood lipids in children from the contaminated areas. The levels were higher in girls than in boys. Some 57 boys and 42 girls were given a basal diet with a diurnal supplementation of 40 mg natural 9-cis and all-trans equal isomer mixture β-carotene in a capsulated powder form of the alga Dunaliella bardawil, for a period of 3 months. Blood serum analyses were regularly conducted before supplementation to determine the baseline effect of radiation exposure to the children, after 1 and 3 months of natural β-carotene supplementation. After supplementation, the levels of the oxidized conjugated dienes decreased in the children's sera without any significant changes in the level of total carotenoids, retinol or α-tocopherol. Other common blood biochemicals were within the normal range for all tests and no statistical differences before or after supplementation of β-carotene were noted. High pressure liquid chromatography (HPLC) analyses for carotenoids in the blood detected mainly oxycarotenoids, and to a lesser extent, all-trans β-carotene, α-carotene, but not 9-cis β-carotene. The results suggest that irradiation increases the susceptibility of lipids to oxidation in the Chernobyl children and that natural β-carotene may act as an in vivo lipophilic antioxidant or radioprotector. Received: 20 March 1998 / Accepted in revised form: 1 August 1998     

Natural β-carotene and whole body irradiation in rats

β-Carotene and other carotenoids are reported to be potent free radical quenchers, singlet oxygen scavengers, and lipid antioxidants. Whole-body irradiation is known to cause an immunosuppression effect in mammals through the possible initiation and production of reactive oxygen species. We decided to test the possible antioxidative effect against whole-body irradiation of a natural β-carotene, composed of equal amounts of the all-trans and 9-cis isomers, obtained from the unicellular alga Dunaliella bardawil. Rats were fed on ground commercial food enriched with natural β-carotene (50 mg/kg diet). On completion of 1 week with β-carotene, the rats were exposed to a single dose of 4 Gy whole-body irradiation, after which their livers and blood were removed for β-carotene and retinol analysis in comparison with control livers of animals irradiated or not, or supplemented with β-carotene after irradiation. A normal increase in body weight with no ill effects was noted in the groups of rats whose diet was supplemented by β-carotene before and after irradiation, compared with the reduction in the specific growth rate in the group of rats irradiated without β-carotene. Liver β-carotene and retinol decreased significantly after irradiation compared with the rats which were not irradiated. This decrease was not shown in rats fed β-carotene prior to irradiation, and the effect of irradiation was partially cured by supplementation with β-carotene after irradiation. High-pressure liquid chromatography (HPLC) analysis of the irradiated animals showed a selective decline in 9-cis β-carotene and in retinol over all-trans β-carotene and retinyl esters. These results suggest that 9-cis β-carotene and retinol protect in vivo against the cellular damage by free radicals induced after whole-body irradiation. Received: 14 May 1996 / Accepted in revised form: 24 June 1996     

Micellar oleic and eicosapentaenoic acid but not linoleic acid influences the β-carotene uptake and its cleavage into retinol in rats

Improving the bioavailability of β-carotene is vital to manage vitamin A deficiency. The influence of micellar oleic (OA), linoleic (LA) and eicosapentaenoic (EPA) acids on plasma β-carotene response and its conversion to retinol has been studied in rats employing single (9 h time course) and repeated (10 days) dose administrations. After a single dose, the levels (area under the curve) of plasma β-carotene and retinyl palmitate in OA and EPA groups were higher (p < 0.05) by 13, 7 and 11, 6 folds than LA group. The liver β-carotene level in OA and EPA groups were higher (p < 0.05) by 3 and 1.2 folds than LA group. After repeated dose, the plasma β-carotene and retinyl palmitate levels in OA (6.2%, 51.7%) and EPA (25.4%, 17.23%) groups were higher (p < 0.05) than LA group. The liver β-carotene level in OA (21.2%) and EPA (17.6%) groups were higher (p < 0.05) than LA group. In both the experiments, the activity of β-carotene 15,15′-dioxygenase in the intestinal mucosa and plasma triglyceride levels were also higher in OA and EPA groups than LA group. β-Carotene excreted through urine and feces of OA and EPA groups was lower than the LA group. These results demonstrate an improved absorption and metabolism of β-carotene when fed mixed micelles with OA or EPA compared with LA. Although the mechanism involved in selective absorption of fatty acids needs further studies, intestinal β-carotene uptake and its conversion to vitamin A can be modulated using specific fatty acids.     

Spray-drying of Dunaliella salina to produce a β-carotene rich powder

Powders of Dunaliella salina biomass were obtained by spray drying a cell concentrate under different drying regimes. A three-factor, two-level experimental design was employed to investigate the influence of inlet temperature, outlet temperature and feed solids on β-carotene recovery. The effect of microencapsulation in a polymer matrix of maltodextrin and gum arabic was also studied. All powders were stored under specific conditions to assess the stability of the native β-carotene. There was a trend indicating that lower outlet temperature yielded higher carotenoid recoveries, β-carotene recovery varying between 57% and 91%. Microencapsulated biomass yielded 100% recoveries. All non-microencapsulated powders were unstable in terms of β-carotene content in the presence of natural light and oxygen showing 90% degradation over a 7-day period. The incorporation of a microencapsulating agent had a significant increase in the storage stability. Results indicated a first-order degradation of the β-carotene in microencapsulated powders with kinetic constants of 0.06 day⁻¹ and 0.10 day⁻¹. HPLC analysis showed no effect of drying processes on isomer composition (9-cis-β-carotene and all-trans-β-carotene ratio). This behaviour was also observed during storage of the microencapsulated powders. Received 16 October 1996/ Accepted in revised form 13 November 1997     

The synthetic peptide octraphin TPLVTLFK is a selective agonist of nonopioid β-endorphin receptor

The peptide TPLVTLFK (coined by the authors “octarphin”), corresponding to the amino acid sequence of β-endorphin fragment 12–19, and its analogs (LPLVTLFK, TLLVTLFK, TPLVLLFK, TPLVTLLK, TPLVTLFL) were synthesized. The peptide octarphin was labeled with tritium (specific activity, 28 Ci/mol) and its binding to the rat brain cortex membranes and mouse peritoneal macrophages was studied. [³H]Octarphin was found to bind to brain membranes and macrophages with high affinity (K _d = 2.6 ±0.2 and 2.3 +0.2 nM, respectively) and specificity. The specific binding of [³H]octarphin with rat brain membranes and mouse macrophages was inhibited by unlabeled β-endorphin (K _i = 2.4 +0.2 and 2.7 +0.2 nM, respectively) and selective agonist of nonopioid β-endorphin receptor synthetic peptide immunorphin (SLTCLVKGFY) (K _i = 2.9 +0.2 and 2.4 +0.2 nM, respectively) and was not inhibited by unlabeled naloxone, α-endorphin, γ-endorphin and [Met⁵]enkephalin (K _i > 10 mM). Inhibiting activity of unlabeled analogs of octarphin was more than 100 times lower than that of the unlabeled octarphin. Octarphin was shown to stimulate activity of mouse immunocompetent cells in vitro: at the concentration of 1 nM it enhanced the capacity of peritoneal macrophages to digest bacteria Salmonella typhimurium virulent strain 415 in vitro. Thus, octarphin is a selective agonist of nonopioid (insensitive to the opioid antagonist naloxone) β-endorphin receptor of rat brain cortex membranes and mouse peritoneal macrophages.     

The vitamin content of microalgae used in aquaculture

The vitamin content in four Australian microalgae, a Nannochloropsis-like sp., Pavlova pinguis, Stichococcus sp. and Tetraselmis sp., were examined. These were grown under a 12:12 h light:dark regimen (100 μmol photon m⁻²s⁻¹) and harvested during late-logarithmic phase. Typically, the content showed a two- to three fold range between the species. When expressed on a dry weight basis, the content of ascorbate ranged from 1.3 to 3.0 mg g⁻¹, β-carotene from 0.37 to 1.05 mg g⁻¹, α-tocopherol from 0.07 to 0.29 mg g⁻¹, thiamine from 29 to 109 μg g⁻¹, riboflavin from 25 to 50 μg g⁻¹, total folates from 17 to 24 μg g⁻¹, pyridoxine from 3.6 to 17 μg g⁻¹, cobalamin from 1.70 to 1.95 μg g⁻¹ and biotin from 1.1 to 1.9 μg g⁻¹. Retinol was detected only in Tetraselmis sp. (2.2 μg g⁻¹); any vitamins D₂ or D₃ were below the detection limit (≤0.45 μg g⁻¹). Nannochloropsis sp. was also grown under a 24:0 h light:dark light cycle and harvested at stationary phase. The content of most vitamins in Nannochloropsis sp. cultures differed significantly, and the degree of variation was similar to that observed between the four species grown under 12:12 h light:dark regimen (100 μmol photon m⁻²s⁻¹) and harvested during late-logarithmic phase. Thiamine content was also examined in six non-Australian strains commonly used in aquaculture, Chaetoceros muelleri, Thalassiosira pseudonana, Nannochloris atomus, Nannochloropsis oculata, Isochrysis sp. (T.ISO) and Pavlova lutheri. Values (average 61 μg g⁻¹; range 40 to 82) were similar to those in the Australian strains (average 61 μg g⁻¹; range 29 to 109) and increased during stationary phase (average 94 μg g⁻¹; 38 to 131). Comparison of the data with the known nutritional requirements for marine fish species and prawns suggests that the microalgae should provide excess or adequate levels of the vitamins for aquaculture food chains. The data may be used to guide the content of vitamins included in micro-diets developed as replacements for live diets. This revised version was published online in July 2006 with corrections to the Cover Date.     

Over-production of β-carotene from metabolically engineered Escherichia coli

To produce recombinant β-carotene in vitro, synthetic operons encoding genes governing its biosynthesis were engineered into Escherichia coli. Constructs harboring these operons were introduced into either a high-copy or low-copy cloning vector. β-Carotene production from these recombinant E. coli cells was either constitutive or inducible depending upon plasmid copy number. The most efficient β-carotene production was with the low-copy based vector. The process was increased incrementally from a 5 l to a 50 l fermentor and finally into a 300 l fermentor. The maximal β-carotene yields achieved using the 50 l and 300 l fermentor were 390 mg l⁻¹ and 240 mg l⁻¹, respectively, with overall productivities of 7.8 mg l⁻¹ h⁻¹ and 4.8 mg l⁻¹ h⁻¹.     

Properties and mechanism of the action of the synthetic peptide octarphin

The peptide TPLVTLFK, whose amino acid sequence corresponds to the 12–19 fragment of β-endorphin (the author’s name for the peptide octarphin), and its analogues (LPLVTLFK, TLLVTLFK, TPLVLLFK, TPLVTLLK, and TPLVTLFL) have been synthesized. Tritium-labeled octarphin (specific activity of 28 Ci/mol) has been obtained, and its binding to murine peritoneal macrophages has been studied. It was found that [³H]octarphin binds to macrophages with a high affinity (K _d 2.3 ± 0.2 nM) and specificity. The specific binding of [³H]octarphin to macrophages was inhibited by the unlabeled β-endorphin and the selective agonist of the nonopioid β-endorphin receptor synthetic peptide immunorphin (SLTCLVKGFY) (K _i 2.7 ± 0.2 and 2.4 ± 0.2 nM, respectively) and was not inhibited by unlabeled naloxone, α-endorphin, γ-endorphin, and [Met5]enkephalin (K _i > 10 μM). The inhibitory activity of the octarphin analogues was more than 100 times lower than that of octarphin. It was shown that octarphin stimulates the activity of mouse immunocompetent cells in vitro and in vivo; at a concentration of 1–10 nM, it increased the adhesion and spreading of peritoneal macrophages and their ability to digest the bacteria of the Salmonella typhimurium virulent strain 415 in vitro. The intraperitoneal injection of the peptide at a dose of 20 μg/animal on day 7, 3, and 1 prior to the isolation of cells led to an increase in the activity of the peritoneal macrophages and the Tand B lymphocytes of the spleen.     

Relationships among the biosyntheses of ubiquinone, carotene, sterols, and triacylglycerols in Zygomycetes

The Zygomycetes Phycomyces blakesleeanus and Blakeslea trispora are actual or potential sources of β-carotene, ergosterol, ubiquinone, edible oil, and other compounds. By feeding [¹⁴C]acetyl-CoA, L-[¹⁴C]leucine, or R-[¹⁴C]mevalonate in the presence of excess unlabeled glucose, we found that ubiquinone (the terpenoid moiety), β-carotene, and triacylglycerols were made from separate pools of all their common intermediates; the pools for ubiquinone and ergosterol were indistinguishable. Fatty acids were not labeled from mevalonate, showing the absence in these fungi of a shunt pathway that would recycle carbon from mevalonate and its products back to central metabolism. The overproduction of carotene in a Phycomyces mutant and in sexually mated cultures of Blakeslea modified the relative use of labeled and unlabeled carbon sources in the production of carotene, but not of the other compounds. We concluded that carotene, ubiquinone, and triacylglycerols are synthesized in separate subcellular compartments, while sterols and ubiquinone are synthesized in the same compartments or in compartments that exchange precursors. Carotene biosynthesis was regulated specifically and not by flow diversion in a branched pathway.     

Substrate specificity of a recombinant chicken <Emphasis Type="Italic">β</Emphasis>-carotene 15,15′-monooxygenase that converts <Emphasis Type="Italic">β</Emphasis>-carotene into retinal

The recombinant β-carotene 15,15′-monooxygenase from chicken liver was purified as a single 60 kDa band by His-Trap HP and Resource Q chromatography. It had a molecular mass of 240 kDa by gel filtration indicating the native form to be tetramer. The enzyme converted β-carotene under maximal conditions (pH 8.0 and 37°C) with a k _cat of 1.65 min⁻¹ and a K _m of 26 μM and its conversion yield of β-carotene to retinal was 120% (mol mol⁻¹). The enzyme displayed catalytic efficiency and conversion yield for β-carotene, β-cryptoxanthin, β-apo-8′-carotenal, β-apo-4′-carotenal, α-carotene and γ-carotene in decreasing order but not for zeaxanthin, lutein, β-apo-12′-carotenal and lycopene, suggesting that the presence of one unsubstituted β-ionone ring in a substrate with a molecular weight greater than C₃₀ seems to be essential for enzyme activity.     

Role of vitamin-zinc interactions on in vitro zinc uptake by human erythrocytes

In vitro zinc uptake by human erythrocytes was studied under a range of zinc concentrations representing three different plasma zinc levels i.e., zinc deficient [0.35–0.61 ppm], zinc normal [0.74–1.59 ppm], and zinc excess [1.65–2.3 ppm]. Further, interactions of physiological levels of riboflavin, flavin adenine dinucleotide (FAD), nicotinic acid, nicotinamide adenine dinucleotide (NAD), thiamine, thiamine pyrophosphate (TPP), folic acid, and ascorbic acid with zinc uptakes were studied in independent experiments. In control experiments, as compared to the normal zinc state, the rate of change of zinc uptake over change in zinc levels was 1.6 times in the excess state and 0.12 times in the deficient state, indicating three distinct patterns. Under the zinc-deficient state, thiamine significantly enhanced the zinc uptakes (p<0.05), whereas ascorbic acid and riboflavin inhibited zinc uptakes (p<0.05). The percent hemolysis of the cells was also significantly lower in the presence of thiamine (p<0.05). Under normal and excess zinc states, the vitamin-zinc interactions were not significant. The results suggest that with erythrocytes as the vehicles, thiamine might be playing an enhancer role in uptake of zinc, whereas the action of ascorbic acid might be inhibitory for zinc uptakes under deficient zinc states.     

Effect of pH, light intensity, salt and nitrogen concentrations on growth and β-carotene accumulation by a new isolate of Dunaliella sp

Summary In the present study Dunaliella sp. that could grow in the Johnson medium was isolated from hypersaline Lake Tuz and its β-carotene production was studied in a batch system, in order to determine the optimal conditions required for the highest β-carotene accumulation. In the experiments with light intensity, the cell numbers and β-carotene content were maximum at pH 9, with 20% of NaCl concentration and 48 kerg cm⁻² s⁻¹ light intensity. At this light intensity, the β-carotene content of Dunaliella sp. ranged between 0.177 and 1.095 mg/ml for the culture broth and 0.119 to 0.261 ng/cell on a per cell basis under the nitrogen limitation. At the end of the experiments, the maximum β-carotene accumulation and the cell number were obtained at pH 7, 5 mM NaNO₃ and 20% NaCl concentrations as 0.261 ng/cell, 4.2×10⁶ cell/ml, respectively.     

Substrate contribution on free radical scavenging capacity of carotenoid extracts produced from <Emphasis Type="Italic">Blakeslea trispora</Emphasis> cultures

Blakeslea trispora produces carotenoids mixtures consisting mainly of lycopene, γ-carotene and β-carotene, together with trace amounts of other carotenoid precursors. The yield of these carotenoids and their composition are greatly affected by culture substrate. The scavenging capacity of carotenoids extract from cultures of B. trispora growing in various substrates was estimated using the 2,2-diphenyl-1-picrylhydrazyl method. Fractions enriched in β-carotene, γ-carotene and lycopene, obtained after column chromatography in alumina basic II, were also examined. Substrates containing starch and oils mixture, Ni²⁺, and that with pantothenic acid presented higher antioxidant activity. An increase in the antioxidant activity of the crude carotenoid extract compared to that of the isolated fractions enriched in β-carotene, γ-carotene and lycopene respectively, observed in most samples, indicated a possible synergistic effect. The results are of interest and by expanding this study to more substrates and other microorganisms- producing antioxidants, a formulation of extract with high free radical scavenging potential could be produced.     

Spectroscopic properties and temperature induced electronic configuration changes of all-<Emphasis Type="Italic">trans</Emphasis> and 15-<Emphasis Type="Italic">cis</Emphasis> β-carotenes in ionic liquids

The clear vibrational structure of fluorescence spectrum of β-carotene in the solvent is reported for the first time at room temperature. This finding is in good agreement with recently discovered covalent 3 ¹A _g ⁻ new carotenoid state. The fluorescence yield of β-carotene in ionic liquid (1-methyl-3-octyloxymethylimidazolium tetrafluoroborate) is around hundred times higher than in standard solvent n-hexane. The all-trans and 15-cis β-carotene fluorescence yields in ionic liquid are 1.96±0.03 and 2.53±0.03 %, respectively. The ionic liquid is a very useful tool for modelling photosynthetic system in situ. We present the electronic absorption data of β-carotene in ionic liquids (so called neoteric solvents) with special interest in the absorption changes as a function of temperature in the range 0–90 °C (273–363 K). Ionic liquids are also very good medium for temperature study, because they are not changing up to several hundred °C and also not evaporating during heating. The relationship between spectral characteristics of β-carotene in new generation solvents with increasing and decreasing temperature is evaluated. The energy value of the ionic state 1 ¹B _u ⁺ of synthetic β-carotene in ionic liquids exhibits a linear and temperature reversible dependence on temperature up to 30 °C (303 K) and up to 40 °C (313 K) for 15-cis and all-trans β-carotenes, respectively. This is valid for both 0-0 and 0-1 transitions.     

Plasma tocopherol,retinol, and carotenoid concentrations in free-ranging Humboldt penguins (Spheniscus humboldti) in Chile

Plasma retinol and α-tocopherol concentrations were measured in heparinized blood samples collected from 51 free-ranging adult Humboldt penguins (Sphenicus humboldti) residing at two colonies off the Chilean coast. Thirty samples were collected in April 1992 from penguins inhabiting the Ex-islote de los Pájaros Niños in Algarrobo, Chile. In September 1992, 21 samples were collected from birds inhabiting Isla de Cachagua, Chile. Samples were assayed for retinol, retinyl palmitate, α-tocopherol, γ-tocopherol, lutein, β-cryptoxanthin, lycopene, α-carotene, and β-carotene. Retinol, α-tocopherol, and lutein were detected in all samples, while lycopene and γ-tocopherol were not detected in any. A significantly higher percentage of samples had detectable levels of retinyl palmitate and α-carotene in April (P < 0.001): for β-cryptoxanthin the percentage was higher in September (P < 0.001). Plasma concentrations of α-tocopherol and lutein were higher in September. Alpha-tocopherol concentrations were 1,877.1 ± 99.0 (SEM) μg/dl in April compared to 2.289 ± 122.3 μg/dl in September (P < 0.05); lutein concentrations were 4.16 ± 0.43 μg/dl in April vs. 10.68 ± 1.02 μg/dl in September (P < 0.001). Retinol concentrations were not significantly different (117 ± 8.0 μg/dl in April vs. 105.3 ± 7.6 μg/dl in September). Both physiologic changes associated with season, and the change in locale may have contributed to the differences seen in the assay means and the number of samples with detectable levels. © 1996 Wiley-Liss, Inc.     

Immunostimulating effect of the synthetic peptide octarphin corresponding to β-endorphin fragment 12–19

We have synthesized the peptide TPLVTLFK corresponding to β-endorphin fragment 12–19 (dubbed octarphin) and its analogs (LPLVTLFK, TLLVTLFK, TPLVLLFK, TPLVTLLK, TPLVTLFL). The octarphin peptide was labeled with tritium (specific activity 28 Ci/mol), and its binding to murine peritoneal macrophages was studied. [³H]Octarphin was found to bind to macrophages with high affinity (K _d = 2.3 ± 0.2 nM) and specificity. The specific binding of [³H]octarphin was inhibited by unlabeled β-endorphin and the selective agonist of nonopioid β-endorphin receptor synthetic peptide immunorphin (SLTCLVKGFY) (K _i = 2.7 ± 0.2 and 2.4 ± 0.2 nM, respectively) and was not inhibited by unlabeled nalox-one, α-endorphin, γ-endorphin, or [Met⁵]enkephalin (K _i > 10 μM). Inhibitory activity of unlabeled octarphin analogs was more than 100 times lower than that of unlabeled octarphin. Octarphin was shown to stimulate activity of murine immuno-competent cells in vitro and in vivo: at concentration of 1–10 nM it enhanced the adhesion and spreading of peritoneal macrophages as well as their ability to digest bacteria of Salmonella typhimurium virulent strain 415 in vitro; the peptide administered intraperitoneally at a dose of 20 μg/animal on day 7, 3, and 1 prior to isolation of cells increased activity of peritoneal macrophages as well as spleen T- and B-lymphocytes.     

Singlet oxygen as a signaling transducer for modulating artemisinin biosynthetic genes in <Emphasis Type="Italic">Artemisia annua</Emphasis>

Although crosstalk between cytosolic and plastidic terpenoid pathways has been validated in many plant species, we report here for the first time a striking elevation of the nucleus-encoded artemisinin biosynthesis relevant DBR2 mRNA following the incubation of plants with fosmidomycin (FM). FM decreased singlet oxygen (¹O₂) scavengers such as β-carotene and α-tocopherol and subsequently invoked ¹O₂ burst. The treatment of plants with fluridone (FD) neither decreased α-tocopherol content nor triggered ¹O₂ emission. In conclusion, FM can up-regulate ¹O₂-sensitive nuclear genes responsible for artemisinin biogenesis by mitigating the accumulation of plastidic scavenging terpenoids, thereby eliciting ¹O₂ generation and initiating ¹O₂ retrograde signaling.