Absence Of UV Light Research Articles

Influence of Natural and Synthetic Compounds on the Infectivity of a Vairimorpha (Microspora) sp. in Trichoplusia ni (Lepidoptera: Noctuidae) Larvae

In this study, we examined the influence of phytochemicals and antiprotozoan drugs on the time to death in Trichoplusia ni (Hubner) larvae infected with a microsporidian pathogen belonging to the genus Vairimorpha . Of the 15 compounds tested, only xanthotoxin, a linear furanocoumarin with phototoxic properties, delayed mortality in infected insects. In the absence of UV light, larvae fed an artificial diet containing 0.02% fresh weight xanthotoxin survived a2 d longer than did their drug-free counterparts. With UV exposure, survival time increased to a3 d longer than that for larvae under drug-free conditions. The alkaloid camptothecin caused developmental delays at concentrations of 0.02% and this delay resulted in enhanced mortality in infected larvae due to their slower growth and therefore smaller size. Other compounds (onion extract containing alkyl sulfides, metronidazole, and albendazole) that have been shown previously to influence microsporidian infection under different conditions had no effect on Vairimorpha ( T. ni isolate) pathogenicity in T. ni . The lack of response of Vairimorpha ( T. ni isolate) to a wide range of biologically active compounds may reflect evolutionary exposure of the phytophagous host to a wide range of toxins.

Syntheses of photoactive analogues of adenosine diphosphate (hydroxymethyl)pyrrolidinediol and photoaffinity labeling of poly(ADP-ribose) glycohydrolase.

Two isomeric azidoadenosyl analogues of adenosine diphosphate (hydroxymethyl)pyrrolidinediol [ADP-HPD; Slama, J. T., et al. (1995) J. Med. Chem. 38, 389-393] were synthesized as photoaffinity labels for poly(ADP-ribose) glycohydrolase. 8-Azidoadenosine diphosphate (hydroxymethyl)pyrrolidinediol (8-N3-ADP-HPD) inhibited the enzyme activity by 50% at ca. 1 microM, a concentration 80-fold lower than that where the isomeric 2-azidoadenosine diphosphate (hydroxymethyl)pyrrolidinediol did. [alpha-32P]-8-N3-ADP-HPD was therefore synthesized and used to photoderivatize poly(ADP-ribose) glycohydrolase. Irradiation of recombinant poly(ADP-ribose) glycohydrolase and low concentrations of [alpha-32P]-8-N3-ADP-HPD with short-wave UV light resulted in the covalent incorporation of the photoprobe into the protein, as demonstrated by gel electrophoresis followed by autoradiography or acid precipitation of the protein followed by scintillation counting. No photoincorporation occurred in the absence of UV light. The photoincorporation saturated at low concentrations of the photoprobe and photoprotection was observed in the presence of low concentrations of ADP-HPD, an indication of the specificity of the photoinsertion reaction. These results demonstrate that [alpha-32P]-8-N3-ADP-HPD can be used to specifically covalently photoderivatize the enzyme to characterize the polypetides that constitute the ADP-HPD binding site of poly(ADP-ribose) glycohydrolase. The photoincorporation reaction was further used to determine the ability of ADP-ribose polymers of varying size to compete with [alpha-32P]-8-N3-ADP-HPD for binding to the enzyme. Photoincorporation of [alpha-32P]-8-N3-ADP-HPD was inhibited by 80% in the presence of low concentrations of short, unbranched ADP-ribose oligomers (5-15 ADP-ribose units in length). No similar photoprotection was afforded by the addition of a high-molecular weight highly branched polymer. These results indicate that the photolabel shares a binding site with the short, linear polymer, but not with the long, highly branched polymer.

Study of olefin epoxidation using binuclear Mn(II) complexes as catalyst in presence and absence of UV light

Mn(II) binuclear complexes of Schiff base ligands have been synthesised by the reaction of MnCl 2·2H 2O in ethanolic solution with the Schiff base obtained by the condensation of pyridine-2-carboxaldehyde and longer aromatic diamines like 44′ diamino diphenyl, 44′ diamino diphenyl methane and 44′ diamino diphenyl ether respectively. These complexes have been characterised by elemental analysis, spectral, magnetic, electrochemical and FAB mass spectral studies. These complexes have been used as catalyst for the epoxidation of olefin using iodosyl benzene as oxidant. The combined effect of light and catalyst on the catalytic activity have also been investigated.

An Arabidopsis photolyase mutant is hypersensitive to ultraviolet-B radiation.

Photolyases are DNA repair enzymes that use energy from blue light to repair pyrimidine dimers. We report the isolation of an Arabidopsis thaliana mutant (uvr2-1) that is defective in photorepair of cyclobutylpyrimidine dimers (CPDs). Whereas uvr2-1 is indistinguishable from wild type in the absence of UV light, low UV-B levels inhibit growth and cause leaf necrosis. uvr2-1 is more sensitive to UV-B than wild type when placed under white light after UV-B treatment. In contrast, recovery in darkness or in light lacking photoreactivating blue light results in equal injury in uvr2-1 and wild type. The uvr2-1 mutant is unable to remove CPDs in vivo, and plant extracts lack detectable photolyase activity. This recessive mutation segregates as a single gene located near the top of chromosome 1, and is a structural gene mutation in the type II CPD photolyase PHR1. This mutant provides evidence that CPD photolyase is required for plant survival in the presence of UV-B light.

An ethnobotanical study of the traditional medicine of the Mestizo people of Suni Miraño, Loreto, Peru

Research on the ethnobotany of Mestizos in Suni Miraño in 1994 documented 60 plant species used for medicinal purposes. Some cultural data on traditional healing and etiology were also collected. Of these 60 species, 31 were submitted to antibacterial and antifungal assays in the presence and absence of UV light and a number of species were shown to be active.

Degradation of commercial azo dyes in water using ozonation and UV enhanced ozonation process

The chemical oxidation of eight non-biodegradable azo dyes by ozonation and photooxidation process was studied in a pilot scale photochemical (UV/ozone) reactor. In experiments with ozone bubbling, the degradation of eight azo dyes was found to occur in the absence of UV light. The degradation rate of azo dyes was observed to be first order with respected to both azo dye and ozone concentrations. The pH of the solution decreased while the azo dyes degraded. UV light did not significantly enhance the degradation ability of the ozonation reaction under various conditions. No degradation was observed when the azo dye solution was irradiated by UV light alone. Effects of ozone dosage, and initial concentrations of azo dyes are discussed. Time for removal of 50 % of azo dye and rate constants can be used to determine the decomposition rate of each azo dye by different oxidation processes as a function of various conditions.

Advances in photochemical approaches for blood sterilization.

Advances in photochemical approaches for blood sterilization.

Effects of aging and washing on UV and ozone-treated poly(ethylene terephthalate) and polypropylene

In this study we investigated the stability of poly(ethylene terephthalate) (PET) and polypropylene (PP) surfaces modified using three combinations of UV light and ozone: ozone only, UV light in air (producing ozone), and UV light in air supplemented by additional ozone in the incoming air. Analysis was done using X-ray photoelectron spectroscopy and dynamic contact angle measurements. Our results showed that PET film is oxidized using these treatment conditions and it changes significantly within the first week of aging and after washing with water. These changes are reflected in the decrease in the Δ(O : C) ratio and the increase in the contact angle. Conversely, PP changes very little on aging or washing. Low-molecular-weight oxidized material (LMWOM), produced on the polymer surfaces treated with UV/air or UV/air + ozone, is easily removed with water washing. On aging PET, a number of the oxidized groups at the surface disappear, seeming to migrate into the bulk. The PP, however, does not favour migration as a path to reduce the overall free energy of the system, so the oxidized groups remain at the surface. Treatment with ozone only, in the absence of UV light, is a much different modification process in terms of the mechanism and the functional groups formed on the surface. This is reflected in the aging and washing behaviour of both the PET and the PP treated with ozone only.

Regulation of Melanogenesis Induced by 5‐Methoxypsoralen Without Ultraviolet Light in Murine Melanoma Cells

Melanogenesis in melanoma cells can be enhanced by psoralens in the absence of UV light. Melanin biosynthesis is regulated by a number of melanocyte-specific proteins, including tyrosinase, DOPAchrome tautomerase (DCT), and tyrosinase-related protein-1 (TRP-1, gp75). To get more insight on the molecular mechanisms involved in psoralens-induced melanogenesis, we determined tyrosinase and DCT activities as well as mRNA and protein levels of tyrosinase, DCT, and TRP-1 in S91 mouse melanoma cells treated by 5-MOP. High concentration of 5-MOP (5 x 10(-5) M) induced a time-dependent increase of tyrosinase activity and melanin content, which was correlated to an increase of both mRNA and protein levels of tyrosinase. These results demonstrate that the 5-MOP stimulation of melanogenesis is related to increased tyrosinase synthesis. In addition, 5-MOP stimulated TRP-1 synthesis and induced a dose-dependent decrease of DCT activity without any modification in the expression of the protein. We explored then the signalling pathways involved in 5-MOP-induced melanogenesis and, particularly, the role of cyclic AMP and protein kinase C (PKC). A small stimulation of cyclic AMP production was observed in presence of 5-MOP. Furthermore, 1-oleoyl-2-acetylglycerol (OAG), a PKC activator, potentiated the 5-MOP stimulation of tyrosinase activity, while calphostin, a specific PKC inhibitor, inhibited the 5-MOP induction of tyrosinase activity. Phorbol-myristate acetate (PMA), described as a strong activator of PKC, inhibited also the effect of 5-MOP when used at long term. Taken together, these results demonstrate that in murine melanoma cells 5-MOP stimulates melanogenesis by increasing activity and synthesis of tyrosinase. Tyrosinase and TRP-1 expression are coordinately regulated by 5-MOP. Furthermore, a negative correlation between melanogenesis and DCT activity was observed under 5-MOP stimulation. At least, PKA and PKC systems appear to play an important role in the melanogenic effect of 5-MOP.

Synthesis of 25-hydroxyvitamin D33.beta.-3'-[N-(4-azido-2-nitrophenyl)amino]propylether, a second-generation photoaffinity analog of 25-hydroxyvitamin D3: photoaffinity labeling of rat serum vitamin D-binding protein

Vulnerability of 25-hydroxy-[26,27-3H]vitamin D3 3 beta-N-(4-azido-2-nitrophenyl)glycinate, a photoaffinity analogue of 25-hydroxyvitamin D3 (25-OH-D3) (Ray et al., 1986) toward standard conditions of carboxymethylation promoted us to synthesize 25-hydroxyvitamin D3 3 beta-3'-[N-(4-azido-2-nitrophenyl)amino]propyl ether (25-ANE), a hydrolytically stable photoaffinity analogue of 25-OH-D3, and 25-hydroxyvitamin D3 3 beta-3'-[N-(4-azido-2-nitro-[3,5-3H]phenyl)amino] propyl ether (3H-25-ANE), the radiolabeled counterpart of 25-ANE. Competitive binding assays of 25-OH-D3 and 25-ANE with rat serum demonstrated that 25-ANE competes for the 25-OH-D3 binding site in rat serum vitamin D binding protein (rDBP). On the other hand, UV exposure of a sample of purified rat DBP (rDBP), preincubated in the dark with 3H-25-ANE, covalently labeled the protein. However, very little covalent labeling was observed in the absence of UV light or in the presence of a large excess of 25-OH-D3. These results provide strong evidence for the covalent labeling of the 25-OH-D3 binding site in rDBP by 3H-25-ANE.

Adaptive significance of furanocoumarin diversity inPastinaca sativa (Apiaceae)

Fruits ofPastinaca sativa (Apiaceae), the edible parsnip, contain six different furanocoumarins that are differentially capable of ultraviolet-mediated cross-linkage of DNA and inhibition of DNA transcription. Individually, none of the other furanocoumarins present in parsnip seeds is as toxic as the photosensitizer xanthotoxin. Nevertheless, the natural mixture of compounds is toxicologically more effective againstHeliothis zea (Lepidoptera: Noctuidae), both in the presence and absence of UV light, than is an equimolar amount of xanthotoxin. The difference in toxicity diminishes with increasing light levels. Thus, a series of structurally related natural products can display toxicity lacking in individual compounds and may represent an adaptive compromise to varying environmental conditions.

Stabilized dam mar picture varnish

AbstractAlthough films of dammar resin cannot be stabilized against photochemical degradation in the presence of ultraviolet light with currently available additives, a remarkable stabilization is obtained with a hindered amine light stabilizer (HALS) if the ultraviolet component of the light source is eliminated. Even in the absence of UV light the effect of HALS can be improved by further addition of a benzotriazole ultraviolet absorber. It is proposed that the UV absorber functions as a radical scavenger under such conditions. Films of dammar containing 2% Tinuvin 292 and 3% Tinuvin 328 remain intact when aged in a xenon arc fadeometer under exclusion of UV light for as long as 3700 hours, while they normally break down in a few hundred hours. After such a period of accelerated aging the original components of the resin are all still intact and the films remain removable with cyclohexane. No yellowing occurs during heat aging after a preceding period of prolonged fadeometer aging. Changes in the films ...

Synthesis and biological activities of a fluorescent photoaffinity analog of vasopressin.

The present study describes the synthesis and biological activities of a vasopressin (VP) analog which binds covalently to receptors via a photoreactive p-azido group in position 3 and which contains a rhodamine label in position 8 for localization of hormone-receptor complexes by image-intensified fluorescence microscopy. 1-Deamino[3-(p-azidophenylalanine)]-N epsilon-rhodamyllysine-VP (Rhod-N3-dLVP) was obtained in a two-step procedure from the precursor 1-deamino[3(p-aminophenylalanine)]-LVP which was synthesized by a solid phase technique. The rat antidiuretic activity of this compound was 0.34 +/- 0.3 U/mg. Although both Rhod-N3-dLVP and its congener without a rhodamine label, N3-dLVP, did not have any hydroosmotic activity in the isolated toad urinary bladder in the absence of UV light, after UV irradiation they increased both urea and water transport across the bladder wall. Moreover, these permeability effects of Rhod-N3-dLVP persisted during prolonged and repeated periods of washout, suggesting that the photoproducts of this analog had formed covalent complexes with toad bladder receptors. Binding of Rhod-N3-dLVP was inhibited when photolysis was carried out in the presence of 1-deamino-LVP. These studies suggest that Rhod-N3-dLVP has the requisite biological properties to serve as a tool for the localization by fluorescence microscopy of VP receptors in various target tissues.

1,6-α-Aminosuberic acid, 3-(p-azidophenylalanine),8-arginine]vasopressin as a photoaffinity label for renal vasopressin receptors: An evaluation

The photoreactive analog of vasopressin [1,6-α-aminosuberic acid, 3-(p-azidophenylalanine),8-arginine]vasopressin was labeled with tritium (specific radioactivity: 39 Ci/mmole). In the absence of UV-light, the tritium-labeled ligand retained a high binding affinity to the vasopressin receptor in plasma membranes from bovine kidney inner medulla (apparent dissociation constant KD: 1.4 × 10−8 M). Renal plasma membranes were irradiated under conditions of a high ratio of specific versus non-specific binding of the reactive ligand. Sodium dodecyl sulfate gel electrophoresis after solubilization and reduction demonstrated the preferential labeling of a polypeptide with an apparent molecular weight of Mr = 32 000. A comparison with stained gels revealed that this protein is a minor constitutent of the bovine kidney membrane. Our results suggest the 32 000-dalton polypeptide is either a component of the vasopressin receptor or that it is located in the immediate vicinity of the vasopressin binding protein.

FTIR-spectroscopic evidence of the generation of acid sulfates by SO 2-oxidation on carbonaceous particles

We used Fourier Transform Infrared (FTIR) spectrometry to study the small particle fractions (0.14 – 1.6 μm A.D.) of aerosol samples collected with a Berner ring jet impactor. These frequently showed complex sulfate band structures that were different from those of (NH 4) 2 SO 4, NH 4HSO 4 or (NH 4) 3 H(SO 4) 2. Similar spectra around 1100 cm −1 were seen with particles sampled from a chamber containing propane flame effluent, steam and SO 2, and with activated carbon exposed to humidity and SO 2 in the absence of UV light. In both types of experiment, acid particles were produced with a low NH 4 + to SO 4 neutralization ratio. Ambient aerosol sampling was performed in the city of Vienna and simultaneously at a rural station 10 km northwest. By correlating the results with differing wind directions, we show that acid sulfate particles, frequently found in the environment, are readily neutralized in Vienna by NH 3 and/or CaCO 3.

Evidence for a major strong binding site for tetrachlorosalicylanilide on human serum albumin.

Abstract— Solutions of human serum albumin(HSA) monomer were irradiated with UV light(360 nm) in the presence of [14C]‐3,3.4′S‐tetrachlorosalicylanilide([14C]‐T4CS).The [14C]‐T4 CS‐labeiled HSA was cleaved by cyanogen bromide and separated into two fractions. These fractions were reduced carboxymethylated and separated into their seven characteristic peptides and monitored for radioactivity. Tetrachlorosalicylanilide was found to bind mainly to one region of the sequence of HSA and this covalent binding site was located in residues 124 (Cys) to 298 (Met) of the molecule. The binding of 3,5‐dichlorosalicylamido‐4‐(2,2,6.6‐tetramethylpiperidine‐l‐oxyl (DCS‐TEMPO),a spin‐label analogue of T4CS, to HSA was studied by electron spin resonance spectroscopy. In the absence of UV light. DCS‐TEMPO bound non‐covalently (k = 6.1 times 106M1) to one major binding site on HSA. These results are evidence for the existence of a major strong binding site for the photochemical binding of T4CS to HSA.

Cardiotonic site directed irreversible inhibition of Na + + K +-ATPase by 3-azidoacetylstrophanthidin, a photochemical analogue of strophanthidin

A photochemical analogue of strophanthidin, 3-azidoacetylstrophanthidin (AAS) was synthesized and tested as a cardiotropic steroid (CS) site directed photoaffinity label for Na + + K +-ATPAse (ATP phosphohydrolase, E.C. 3.6.1.3). AAS-inhibited rat brain ATPase with an I 50 of about 1 × 10 −6 M readily displaced 3H-ouabain from its specific binding sites on this enzyme and produced a positive inotropic effect in guinea pig atrial strips. In the absence of UV light its interaction with the CS binding sites of Na + + K +-ATPase appeared reversible. In the presence of UV light and acetylphosphate, AAS produced about 15% irreversible inhibition of Na + + K +-ATPase, compared with about 5% irreversible inhibition in the absence of either UV light or acetyl phosphate. Since acetylphosphate supports specific glucoside binding at the CS binding sites of Na + + K +-ATPase these data are consistent with the concept that AAS is a cardiotonic steroid site directed photoactivatable inhibitor of Na + + K +-ATPase.