Synthesis, structure and antimicrobial activities of meso silver(I) histidinate [Ag2(D-his)(L-his)]n (Hhis = histidine) showing different self-assembly from those of chiral silver(I) histidinates

An achiral coordination polymer, [Ag₂(D-his)(L-his)]_n, DL-1 (Hhis = histidine), was prepared by slow diffusion of two aqueous solutions of chiral complexes, {[Ag(D-his)]₂}_n (D-2) and {[Ag(L-his)]₂}_n (L-2).¹ The crystal structure of DL-1 consists of a linkage of meso-form dimer units through two kinds of Ag?Ag contacts. Crystals of the achiral silver(I) histidinate complex DL-1 exhibited different self-assembly from those of chiral helical polymers (D-3 and L-3). The formation of DL-1 from the two aqueous solutions indicated that ligand exchange around silver(I) atoms took place in water. The antimicrobial activities of DL-1 against selected bacteria, yeasts and molds were evaluated by minimum inhibitory concentration (MIC).     

Effect of intramuscular injections of DL-α-tocopheryl acetate on growth performance and extracellular matrix of growing lambs

The effect of intramuscular injections of vitamin E on growth, carcass traits, intramuscular collagen (IMC) characteristics and decorin of growing lambs was studied. A total of 24 15-day-old Ile de France suckling male lambs were divided into two groups and weekly intramuscular injections of DL-α-tocopheryl acetate (control group, 0 IU; Vitamin E treatment, 150 IU) were given until the lambs were 64 days old. Lambs were individually weighted at 15, 29, 43, 57 days of age and at slaughter (71 days old). Dry matter intake and average daily weight gain were recorded. Hot and cold carcass weights were recorded and dressing percentages were calculated after dressing and chilling (2°C to 4°C for 24 h). Carcass shrink losses were calculated as well. Longissimus muscle (LM) pH and area were measured. The pelvic limb was removed and its percentage was calculated based on cold carcass weight. IMC and decorin analyses were assessed on LM and semimembranosus muscle (SM). DL-α-tocopheryl acetate treatment reduced (P<0.05) collagen maturity and increased (P<0.05) decorin in both LM and SM muscles of growing lambs, while it did not affect IMC content. In addition, vitamin E did not influence growth, carcass weight, dressing percentage, carcass shrink losses and area of LM but decreased (P<0.05) the pelvic limb percentage. The LM pH values were higher (P<0.05) in vitamin group than in control group. Furthermore, different IMC characteristics between the muscles (P<0.01) were apparent. Multiple intramuscular injections of DL-α-tocopheryl acetate influence extracellular matrix in lambs, which could affect meat tenderness.     

Sphingosine-1-phosphate (S1P) mediates darkness-induced stomatal closure through raising cytosol pH and hydrogen peroxide (H2O2) levels in guard cells in Vicia faba

The role and signaling of sphingosine-1-phosphate (S1P) during darkness-induced stomatal closure were examined in Vicia faba. Darkness substantially raised S1P and hydrogen peroxide (H₂O₂) levels and closed stomata. These darkness effects were significantly suppressed by DL-threo-dihydrosphingosine (DL-threo-DHS) and N,N-dimethylsphingosine (DMS), two inhibitors of long-chain base kinases. Exogenous S1P led to stomatal closure and H₂O₂ production, and the effects of S1P were largely prevented by the H₂O₂ modulators ascorbic acid, catalase, and diphenyleneiodonium. These results indicated that S1P mediated darkness-induced stomatal closure by triggering H₂O₂ production. In addition, DL-threo-DHS and DMS significantly suppressed both darkness-induced cytosolic alkalization in guard cells and stomatal closure. Exogenous S1P caused cytosolic alkalization and stomatal closure, which could be largely abolished by butyric acid. These results demonstrated that S1P synthesis was necessary for cytosolic alkalization during stomatal closure caused by darkness. Furthermore, together with the data described above, inhibition of darkness-induced H₂O₂ production by butyric acid revealed that S1P synthesis-induced cytosolic alkalization was a prerequisite for H₂O₂ production during stomatal closure caused by darkness, a conclusion supported by the facts that the pH increase caused by exogenous S1P had a shorter lag and peaked faster than H₂O₂ levels and that butyric acid prevented exogenous S1P-induced H₂O₂ production. Altogether, our data suggested that darkness induced S1P synthesis, causing cytosolic alkalization and subsequent H₂O₂ production, finally leading to stomatal closure.     

On the stereochemistry of 2,3-dihydroxy fatty acids of fungi sphingolipids. Resolution and configuration analysis of erythro-2,3-dihydroxyoctadecanoic acid

DL-erythro-2,3-dihydroxyoctadecanoic acid, synthesized according to Palameta and Pro?tenik (Tetrahedron, 19 (1969) 1463) was converted to the R(+)-1-phenylethylamide and the obtained diastereomers resolved by chromatography on silica gel. The enantiomeric erythro-2,3-dihydroxyoctadecanoic acids were recovered by acidic hydrolysis (m.p., 117°, [α]_D²² = ±3.28°, [M_D²² = ±10.38°). A comparison of the chromatographic mobility of R- and S-1-phenylethylamides and the optical rotation of 2,3-dihydroxy fatty acids from fungi sphingo-lipids shows that the natural occurring enantiomer has (+)D-erythro configuration.     

Isoleucine production in bifidobacteria

Summary About 300 strains of bifidobacteria were examined for their capacity to release L-isoleucine in the fermentation broth. A strain of the speciesBifidobacterium ruminale was selected as the best producer. After treatment of this strain with NTG a DL--aminobutyric acid-resistant mutant capable of producing about 5 mg/ml of L-isoleucine in presence of 1.5 % DL--aminobutyric acid was obtained. Cultural conditions and acetohydroxyacid synthetase activity were studied.     

Studies related to the synthesis of derivatives of 2,6-diamino-2,3,4,6-tetradeoxy-D-erythro-hexose (purpurosamine C), a component of gentamicin C12

Reduction of 1,6-anhydro-3,4-dideoxy-β-D-glycero-hex-3-enopyranos-2-ulose (levoglucosenone) with lithium aluminium hydride afforded principally 1,6-anhydro-3,4-dideoxy-β-D-threo-hex-3-enopyranose (3), which was converted into 3,4-dihydro-2(S)-hydroxymethyl-2H-pyran (8) following acid-catalysed methanolysis and reductive rearrangement of the resulting α-glycoside 4 with lithium aluminium hydride. 1,6-Anhydro-3,4-dideoxy-2-O-toluene-p-sulphonyl-β-D-threo-hexopyranose, prepared from 3, reacted slowly with sodium azide in hot dimethyl sulphoxide to give 1,6-anhydro-2-azido-2,3,4-trideoxy-β-D-erythro-hexopyranose, which was transformed into a mixture of methyl 2-acetamido-6-O-acetyl-2,3,4-trideoxy-α-D-erythro-hexopyranoside (10) and the corresponding β anomer following acid-catalysed methanolysis, catalytic reduction, and acetylation. Acid treatment of methyl 4,6-O-benzylidene-3-deoxy-α-D-erythro-hexopyranosid-2-ulose yielded the enone 15, which was readily transformed into methyl 6-O-acetyl-3,4-dideoxy-α-D-glycero-hexopyranosid-2-ulose (19). Procedures for the conversions of DL-8, 10, and 19 into methyl 2,6-diacetamido-2,3,4,6-tetradeoxy-α-D-erythro-hexopyranoside (methyl N,N′-di-acetyl-α-purpurosaminide C) have already been described.     

Increase in isoleucine accumulation by α-aminobutyric acid-resistant mutants ofBifidobacterium Ruminale

Summary A number of DL--aminobutyric acid-resistant mutants ofBifidobacterium ruminale were isolated. Several of these mutants were found to be superior to the parent strain in converting -aminobutyric acid to L-isoleucine and in the valine accumulation. One of them accumulated over 9 mg/ml of L-isoleucine in presence of 3% DL--aminobutyric acid and 3 mg/ml of L-valine in absence of the precursor.     

Polyamine Biosynthetic Enzymes and the Effect of their Inhibition on the Growth of Some Phytopathogenic Fungi

Studies were conducted on the distribution of two polyaminebiosynthetic enzymes, or-nithine decarboxylase (ODC) and argininedecarboxylase (ADC), and the effect of their inhibitors on growthand polyamine biosynthesis in four phytopathogenic fungi, namely,Helminthosporium maydis, H. carbonum, Fusarium oxysporum f.sp. lycopersici and Ceratocystis ulmi. Three species had highlevel of ODC as compared to ADC activity; in C. ulmi on theother hand, ADC was predominant with very little or no ODC activity.DL--difluoromethylornithine (DFMO) significantly inhibited ODCactivity in all species in vitro with little effect on ADC activity.ADC in all cases was inhibited by DL--difluoromethylarginine(DFMA) but not by DFMO. Mycelial growth of all fungi was inhibitedby 1 to 5 mM concentrations of either DFMO or DFMA within twodays except in H. maydis which remained unaffected even by thehighest concentration (5 mM) of DFMA. In general, the inhibitionwas more pronounced with DFMO as compared to DFMA. Putrescinecompletely reversed the inhibitory effects of DFMO and DFMAin all species. Among the polyamines, spermidine was predominantin all fungi. The cellular concentrations of putrescine andspermidine were considerably lower in the presence of eitherof the inhibitors while spermine levels were higher than thecontrol. ¹Scientific contribution number 1529 from the New HampshireAgricultural Experiment Station. (Received November 25, 1988; Accepted April 11, 1989)     

Polyamine Biosynthesis during Vegetative and Floral Bud Differentiation in Thin Layer Tobacco Tissue Cultures

Levels of putrescine, spermidine and spermine increase whenvegetative or floral buds form in cultures derived from surfaceexplants of inflorescences of Nicotiana tabacum L. cv. Wisconsin-38.Concomitantly, the activity of arginine decarboxylase (ADC)rises and that of ornithine decarboxylase (ODC) declines. DL--Difluoromethylarginine(DFMA), a specific suicide inhibitor of ADC, inhibits bud initiation,while DL--difluoromethylornithine (DFMO), the analogous suicideinhibitor of ODC, does not. On the other hand, DFMO inhibitsthe subsequent development of newly regenerated floral buds,while DFMA does not. It thus appears that polyamines derivedthrough ADC may be involved in bud initiation, while polyaminesderived through ODC are required for subsequent growth and developmentof such buds. Especially large increases of spermidine are associatedwith floral bud differentiation, indicating a possible specialmorphogenetic role for that polyamine. ¹Present address: Laboratori de Fisiologia Vegetal, Facultadde Farmacia, Universitat de Barcelona, 08028 Barcelona, Spain (Received April 25, 1988; Accepted August 12, 1988)     

Suppression of synthesis of serotonin: Effect on antinociception induced by microwave irradiation and analgesic remedies

We studied isolated and combined antinociceptive effects of analgesics (Analginum and Tramadol), as well as of microwave irradiation of an acupuncture point, in mice under conditions of suppression of synthesis of serotonin by an inhibitor of this synthesis, DL-p-chlorophenylalanine (p-CPA). Preliminary introduction of p-CPA weakened the antinociceptive effect of microwave irradiation and also moderated the combined effects of analgesics and microwave irradiation. Neirofiziologiya/Neurophysiology, Vol. 38, Nos. 5/6, pp. 498–499, September–December, 2006.     

Cytological events induced by the inhibition of polyamine biosynthesis in thin cell layers of tobacco

Summary The proliferative growth of thin cell layers ofNicotiana tabacum cultured on a rhizogenic medium was markedly disturbed when polyamine biosynthesis was inhibited. Treatments with polyamine inhibitors led to cell expansion, accompanied by thinning of the cell wall and inhibition of cell division, and frequent cases of nucleolar extrusion, mainly in the parenchymal layer in contact with the medium. Nucleolar extrusion was not correlated with cell expansion. The highest incidence of nucleolar extrusion occurred when the pathways of putrescine biosynthesis were inhibited and when spermidine synthesis, via S-adenosylmethionine decarboxylase, was blocked. The duration of the growth phase with nuclear amitotic divisions was prolonged in the presence of the inhibitors and root meristem formation delayed. When polyamines were added with the inhibitors, all reactions proceeded as in the controls.Abbreviations CHA cyclohexylamine - DFMA DL--difluoromethyl-arginine - DFMO DL--difluoromethylornithine - LS longitudinal section - MGBG methylglyoxal-bis(guanylhydrazone) - PA polyamine - Pu putrescine - RLS radial longitudinal section - S.E. standard error - Spd spermidine     

Studies on lysine analogs,aspartate-derived amino acids,and attempted mutant selection on oat seedlings

The lysine analogs S-2-aminoethyl-L-cysteine (AEC) and DL--hydroxylysine (DHL) caused severe growth inhibition in dark-grown oat seedlings (Avena sativa L. and A. nuda L.) at similar concentrations while L-lysine methyl ester (LME) had little effect. Lysine, arginine, and ornithine reversed the inhibition caused by AEC and DHL, the order of effectiveness being lysine>arginine>ornithine. Of aspartate-pathway amino acids, tested individually and in combinations for inhibitory effects on seedling growth, lysine and combinations containing lysine were the most inhibitory, but the inhibition was much less than that produced by AEC. Only slight synergistic effects occurred when oat seedlings were grown in the presence of paired combinations of aspartatepathway endproduct amino acids.Ca. 54,000 seeds obtained from 3,463 plants grown from ethyl-methanesulfonate (EMS) treated seed were screened for resistance to AEC. Three resistant variants were identified but the resistance was not recovered among their self-pollinated progeny.Abbreviations AEC S-2-aminoethyl-L-cysteine - DHL DL--hydroxylysine - EMS ethyl methanesulfonate - LME L-lysine methyl ester Paper No. 10351, Scientific Journal Series, Minnesota Agricultural Experiment Station     

The cyclization of 3-O-benzyl-6-deoxy-6-nitro-D-glucose and -L-idose to O-benzyldeoxynitroinositols,and epimerizations related thereto

3-O-Benzyl-1,2-O-isopropylidene-α-D-xylo-pentodialdo-1,4-furanose (1) was found to give, with nitromethane under catalysis by sodium methoxide, 3-O-benzyl-6-deoxy-1,2-O-isopropylidene-6-nitro- α-D-glucofuranose (2) as the kinetically favored product. Subsequent, spontaneous epimerization led to a 2:1 mixture of 2 and its β-L-ido isomer (3), from which crystalline 3 was isolated. The free nitro hexoses (4 and 5) obtained by deacetonation of 2 and 3 were subjected to barium hydroxide-catalyzed cyclization (internal Henry reaction) to give mixtures of O-benzyldeoxynitroinositols. Under conditions of kinetic control, the α-D-gluco derivative 4 furnished 6-O-benzyl-3-deoxy-3-nitro-muco-inositol (6) and optically active 4-O-benzyl-1-deoxy-1-nitro-L-myo-inositol (L-7) in a ratio of 3:1. The β-L-ido derivative 5 gave the enantiomer (D-7) of the myo compound and 4-O-benzyl-1-deoxy-1-nitro-scyllo-inositol (8) in a similar ratio. Slow, thermodynamically controlled epimerization led from each individual nitro inositol to mixtures of the same composition, with 17–18% of 6, 68–69% of DL-7, and 11–12% of 8. All of the nitroinositol benzyl ethers were isolated crystalline and characterized further as crystalline tetraacetates (6a–8a). The muco isomer 6 gave a di-O-isopropylidene derivative (6b).     

Cadaverine formation by specific lysine decarboxylation in Pisum sativum seedlings

Cadaverine was found to be formed in Pisum sativum seedlings via a specific lysine decarboxylation pathway as revealed by specific inhibitor studies. Lysine decarboxylation activity was recorded in the meristems and non-meristematic tissue of the shoots and the roots. In the shoot elongation zone, the specific activity was double that in the other tissues and cadaverine level was 90-fold higher. The results presented in this study suggest possible regulatory control by polyamines of lysine decarboxylase activity in Pisum sativum seedlings.Abbreviations LDC lysine decarboxylase - -DFMO DL--difluoromethyl ornithine - -DFMA DL--difluoromethyl arginine - PLP pyridoxal phosphate - DTT dithiothreitol This paper is Contribution No. 1380-E, 1985 series, from the Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel     

Involvement of the Serotonergic System in Analgesia Induced by the Influence of Low-Intensity Microwaves on an Antipain Acupuncture Point

In experiments on mice, we studied changes in the level of analgesia induced by irradiation of the antipain acupuncture point (AP) E36 by low-intensity microwaves under conditions of modification of the serotonin level in the brain; this level was modified by injection of 300 mg/kg DL-p-chlorophenylalanine (pCPA). The duration of the nociceptive behavioral reaction (licking the limb) caused by injection of the formalin solution into the foot dorsal surface increased 24, 48, and 72 h after pCPA injection by 99.9, 84.4, and 114.4%, as compared with those in animals subjected to microwave irradiation of the AP E36 with no preliminary pCPA injection. It is concluded that the brain serotonergic system is actively involved in the analgesia effects induced by irradiation of the AP by low-intensity microwaves.     

Effects of acid stress on polyamine levels,ion efflux,protective enzymes and macromolecular synthesis in cereal leaves

Wheat or oat leaf segments were floated on acid solutions and the changes in several parameters measured. The putrescine content of wheat leaves was 12.8-fold greater at pH 3.5 than at pH 6 after 72 h. The increase in putrescine was accompanied by an increase in the amount of K⁺ efflux from the leaf tissue to the external solution. The activities of superoxide dismutase and catalase of wheat leaves at pH 3.5 decreased to 51% and 40%, respectively, of their levels at pH 6 by 24 h. [³H]Uridine and [³H]leucine incorporation into macromolecules in oat leaves (with the lower epidermis removed) decreased to 58% and 28% of the control in response to acid stress in 8 h, at the same time as a 5-fold increase in putrescine. When DL--difluoro-methyarginine was added to the pH 3.5 buffered solution, the effect of acid was slightly less, with the incorporation into macromolecules being 64% and 35% of the pH 6 control. The results indicated that the putrescine accumulation under acid stress was concomitant with ion efflux, and a decrease in both macromolecular synthesis and the activities of superoxide dismutase and catalase in cereal leaves.Abbreviations Put putrescine - Spd spermidine - Spm spermine - SOD superoxide dismutase - CAT catalase - ADC arginine decarboxylase - DFMA DL--difluoromethylarginine This paper is dedicated to Dr. A.W. Galston in honor for his great achievements and in recognition of his continuing contributions to the study of plant science.     

Recent advances in the understanding of polyamine functions during plant development

Suggested roles for polyamine function, and the evidence for these functions, is reviewed. These include membrane stabilization, free radical scavenging, effects on DNA, RNA and protein synthesis, effects on the activities of RNase, protease and other enzymes, the interaction with ethylene biosynthesis, and effects on second messengers. It is concluded that in addition to interacting with plant hormones, polyamines are able to modulate plant development through a fundamental mechanism(s) common to all living organisms.Abbreviations ACC 1-aminocyclopropane-1-carboxylic acid - ADC arginine decarboxylase - Chl chlorophyll - DAP diaminopropane - DFMA DL--difluoromethylarginine - DFMO DL--difluoromethylornithine - PAs polyamines - Put putrescine - SAM S-adenosylmethionine - Spd spermidine - Spm spermine     

Activation and Inactivation of Alcohol Dehydrogenase in Germinating Pea Cotyledons

Alcohol dehydrogenase (E.C.1.1.1.1.) activity increases markedly in the germinating pea cotyledon in the first 2 days. The activity was not suppressed by the administration of actinomycin D, 6-methylpurine, DL-p-fluorophenylalanine, and D-chloramphenicol. The compounds rather depressed the decrease of alcohol dehydrogenase activity in cotyledons after 3 days of germination. The alcohol dehydrogenase activity in ungerminated pea seeds was activated by treatment with sodium lauryl sulphate, sodium dioctyl sulfosuccinate, dithiothreitol, 2-mercaptoethanol and NADH. The inhibitory effect caused by the extract from 7 day-old cotyledons was diminished markedly in the presence of dithiothreitol and 2-mercaptoethanol, as well as by addition of bovine serum albumin. If dithiothreitol was added to the extraction medium, the enzyme activity from older cotyledons was greatly enhanced.     

Stomatal closure induced by phytosphingosine-1-phosphate and sphingosine-1-phosphate depends on nitric oxide and pH of guard cells in <Emphasis Type="Italic">Pisum sativum</Emphasis>

Main conclusion

Phyto-S1P and S1P induced stomatal closure in epidermis of pea ( Pisum sativum ) by raising the levels of NO and pH in guard cells. Phosphosphingolipids, such as phytosphingosine-1-phosphate (phyto-S1P) and sphingosine-1-phosphate (S1P), are important signaling components during drought stress. The biosynthesis of phyto-S1P or S1P is mediated by sphingosine kinases (SPHKs). Although phyto-S1P and S1P are known to be signaling components in higher plants, their ability to induce stomatal closure has been ambiguous. We evaluated in detail the effects of phyto-S1P, S1P and SPHK inhibitors on signaling events leading to stomatal closure in the epidermis of Pisum sativum. Phyto-S1P or S1P induced stomatal closure, along with a marked rise in nitric oxide (NO) and cytoplasmic pH of guard cells, as in case of ABA. Two SPHK inhibitors, DL-threo dihydrosphingosine and N’,N’-dimethylsphingosine, restricted ABA-induced stomatal closure and prevented the increase of NO or pH by ABA. Modulators of NO or pH impaired both stomatal closure and increase in NO or pH by phyto-S1P/S1P. The stomatal closure by phyto-S1P/S1P was mediated by phospholipase D and phosphatidic acid (PA). When present, PA elevated the levels of pH, but not NO of guard cells. Our results demonstrate that stomatal closure induced by phyto-S1P and S1P depends on rise in pH as well as NO of guard cells. A scheme of signaling events initiated by phyto-S1P/S1P, and converging to cause stomatal closure, is proposed.

     

Effect of amino acids on production of xylanase and pectinase from Streptomyces sp. QG-11-3

Xylanase and pectinase production by Streptomyces sp. QG-11-3 was stimulated by DL-norleucine, L-leucine, DL-isoleucine, L-lysine monohydrochloride and DL--phenylalanine by up to 3.72- and 2.78-fold, respectively, whereas the combination of DL-norleucine, L-leucine and DL-isoleucine synergistically stimulated the xylanase and pectinase production by up to 6.72- and 5.62-fold, respectively. Glycine, DL-norvaline, DL-methionine, and DL-aspartic acid showed no significant stimulatory effect on enzyme production.