Roles for the yeast RAD18 and RAD52 DNA repair genes in UV mutagenesis.

PubMed

Armstrong, J D; Chadee, D N; Kunz, B A

1994-11-01

Experimental evidence indicates that although the Saccharomyces cerevisiae RAD18 and RAD52 genes are not required for nucleotide excision repair, they function in the processing of UV-induced DNA damage in yeast. Conflicting statements regarding the UV mutability of strains deleted for RAD18 prompted us to re-examine the influence of RAD18, and RAD52, on UV mutagenesis. To do so, we characterized mutations induced by UV in SUP4-o, a yeast suppressor tRNA gene. SUP4-o was maintained on a plasmid in isogenic strains that either carried one of two different rad18 deletions (rad18 delta) or had RAD52 disrupted. Both rad18 deletions decreased the frequency of UV-induced SUP4-o mutations to levels close to those for spontaneous mutagenesis in the rad18 delta backgrounds, and prevented a net increase in mutant yield. A detailed analysis of mutations isolated after UV irradiation of one of the rad18 delta strains uncovered little evidence of the specificity features typical for UV mutagenesis in the isogenic repair-proficient (RAD) parent (e.g., predominance of G.C-->A.T transitions). Evidently, UV induction of SUP4-o mutations is highly dependent on the RAD18 gene. Compared to the RAD strain, disruption of RAD52 reduced the frequency and yield of UV mutagenesis by about two-thirds. Closer inspection revealed that 80% of this reduction was due to a decrease in the frequency of G.C-->A.T transitions. In addition, there were differences in the distributions and site specificities of single base-pair substitutions. Thus, RAD52 also participates in UV mutagenesis of a plasmid-borne gene in yeast, but to a lesser extent than RAD18.

Analysis of mutagenic DNA repair in a thermoconditional mutant of Saccharomyces cerevisiae. III. Dose-response pattern of mutation induction in UV-irradiated rev2ts cells.

PubMed

Siede, W; Eckardt, F

1986-01-01

Recent studies regarding the influence of cycloheximide on the temperature-dependent increase in survival and mutation frequencies of a thermoconditional rev2 mutant lead to the suggestion that the REV2-coded mutagenic repair function is UV-inducible. In the present study we show that stationary-phase rev2ts cells are characterized by a biphasic linear-quadratic dose-dependence of mutation induction ("mutation kinetics") of ochre alleles at 23 degrees C (permissive temperature) but linear kinetics at the restrictive temperature of 36 degrees C. Mathematical analysis using a model based on Poisson statistics and a further mathematical procedure, the calculation of "apparent survival", support the assumption that the quadratic component of the reverse mutation kinetics investigated can be attributed to a UV-inducible component of mutagenic DNA repair controlled by the REV2 gene.

TP53 mutations in squamous-cell carcinomas of the conjunctiva: evidence for UV-induced mutagenesis.

PubMed

Ateenyi-Agaba, Charles; Dai, Min; Le Calvez, Florence; Katongole-Mbidde, Edward; Smet, Anouk; Tommasino, Massimo; Franceschi, Silvia; Hainaut, Pierre; Weiderpass, Elisabete

2004-09-01

Squamous cell carcinoma of the conjunctiva is associated with sun exposure and often occurs in HIV-positive individuals. We have analysed TP53 mutations in 21 cases of squamous cell carcinoma and 22 controls with benign conjunctival lesions from a region (Uganda, Africa) with a high prevalence of heavy sun exposure and HIV infection. TP53 mutations were detected in 11 cases (52%) and 3 controls (14%). Seven of the mutations (6 in cases and 1 in controls) were CC-->TT transitions, a molecular signature of mutagenesis by solar UV rays. A similar prevalence (56%) of TP53 mutations was found in 18 squamous cell carcinoma cases positive for epidermodysplasia verruciformis human papillomavirus types. The prevalence of CC-->TT transitions reported here is the highest observed in any cancer type and matches that of skin cancers in subjects with xeroderma pigmentosum, an inherited disease with hypersensitivity to UV damage. These results confirm at the molecular level the causal role of solar UV rays in the aetiology of squamous cell carcinoma of the conjunctiva and suggest that infection with epidermodysplasia verruciformis types of human papillomavirus may act as a cofactor to increase the sensitivity of conjunctiva cells to UV-induced mutagenesis.

A C. elegans homolog for the UV-hypersensitivity syndrome disease gene UVSSA.

PubMed

Babu, Vipin; Schumacher, Björn

2016-05-01

The transcription-coupled repair pathway (TC-NER) plays a vital role in removing transcription-blocking DNA lesions, particularly UV-induced damage. Clinical symptoms of the two TC-NER-deficiency syndromes, Cockayne syndrome (CS) and UV-hypersensitivity syndrome (UVSS) are dissimilar and the underlying molecular mechanism causing this difference in disease pathology is not yet clearly understood. UV-stimulated scaffold protein A (UVSSA) has been identified recently as a new causal gene for UVSS. Here we describe a functional homolog of the human UVSSA gene in the nematode Caenorhabditis elegans, uvs-1 (UVSSA-like-1). Mutations in uvs-1 render the animals hypersensitive to UV-B irradiation and transcription-blocking lesion-inducing illudin-M, similar to mutations in TC-NER deficient mutants. Moreover, we demonstrate that TC-NER factors including UVS-1 are required for the survival of the adult animals after UV-treatment. Copyright © 2016 Elsevier B.V. All rights reserved.

General and inducible hypermutation facilitate parallel adaptation in Pseudomonas aeruginosa despite divergent mutation spectra.

PubMed

Weigand, Michael R; Sundin, George W

2012-08-21

The successful growth of hypermutator strains of bacteria contradicts a clear preference for lower mutation rates observed in the microbial world. Whether by general DNA repair deficiency or the inducible action of low-fidelity DNA polymerases, the evolutionary strategies of bacteria include methods of hypermutation. Although both raise mutation rate, general and inducible hypermutation operate through distinct molecular mechanisms and therefore likely impart unique adaptive consequences. Here we compare the influence of general and inducible hypermutation on adaptation in the model organism Pseudomonas aeruginosa PAO1 through experimental evolution. We observed divergent spectra of single base substitutions derived from general and inducible hypermutation by sequencing rpoB in spontaneous rifampicin-resistant (Rif(R)) mutants. Likewise, the pattern of mutation in a draft genome sequence of a derived inducible hypermutator isolate differed from those of general hypermutators reported in the literature. However, following experimental evolution, populations of both mutator types exhibited comparable improvements in fitness across varied conditions that differed from the highly specific adaptation of nonmutators. Our results suggest that despite their unique mutation spectra, general and inducible hypermutation can analogously influence the ecology and adaptation of bacteria, significantly shaping pathogenic populations where hypermutation has been most widely observed.

Acquisition of pro-oxidant activity of fALS-linked SOD1 mutants as revealed using circular dichroism and UV-resonance Raman spectroscopy

NASA Astrophysics Data System (ADS)

Fujimaki, Nobuhiro; Nishiya, Ken; Miura, Takashi; Nakabayashi, Takakazu

2016-11-01

The acquisition of pro-oxidant activity of the mutated form of human Cu, Zn-superoxide dismutase (SOD1) has been investigated to clarify the relationship between mutations in SOD1 and the pathogenesis of amyotrophic lateral sclerosis (ALS). Ala4 → Val (A4V) and Gly93 → Ala (G93A) mutants, which are representative ALS-linked SOD1 mutants, have been found to exhibit both the denaturation and the gain of pro-oxidant activity after incubation in the apo-form at a physiological condition of 37 °C and pH 7.4 and the rebinding of Cu2+. These characteristics are similar to those previously reported for the His43 → Arg (H43R) mutant. UV-resonance Raman spectra indicated that the coordination structure of the Cu-binding site catalyzing the oxidation reaction is the same among the denatured A4V, G93A, and H43R. Since wild-type SOD1 does not exhibit the denaturation in its apo-form at 37 °C and pH 7.4, the instability of the protein structure due to mutation can be considered as a significant factor that induces the denaturation and the subsequent pro-oxidant activity.

Ultraviolet A within Sunlight Induces Mutations in the Epidermal Basal Layer of Engineered Human Skin

PubMed Central

Huang, Xiao Xuan; Bernerd, Françoise; Halliday, Gary Mark

2009-01-01

The ultraviolet B (UVB) waveband within sunlight is an important carcinogen; however, UVA is also likely to be involved. By ascribing mutations to being either UVB or UVA induced, we have previously shown that human skin cancers contain similar numbers of UVB- and UVA-induced mutations, and, importantly, the UVA mutations were at the base of the epidermis of the tumors. To determine whether these mutations occurred in response to UV, we exposed engineered human skin (EHS) to UVA, UVB, or a mixture that resembled sunlight, and then detected mutations by both denaturing high-performance liquid chromatography and DNA sequencing. EHS resembles human skin, modeling differential waveband penetration to the basal, dividing keratinocytes. We administered only four low doses of UV exposure. Both UVA and UVB induced p53 mutations in irradiated EHS, suggesting that sunlight doses that are achievable during normal daily activities are mutagenic. UVA- but not UVB-induced mutations predominated in the basal epidermis that contains dividing keratinocytes and are thought to give rise to skin tumors. These studies indicate that both UVA and UVB at physiological doses are mutagenic to keratinocytes in EHS. PMID:19264911

Mutation induction in haploid yeast after split-dose radiation exposure. II. Combination of UV-irradiation and X-rays.

PubMed

Keller, B; Zölzer, F; Kiefer, J

2004-01-01

Split-dose protocols can be used to investigate the kinetics of recovery from radiation damage and to elucidate the mechanisms of cell inactivation and mutation induction. In this study, a haploid strain of the yeast, Saccharomyces cerevisiae, wild-type with regard to radiation sensitivity, was irradiated with 254-nm ultraviolet (UV) light and then exposed to X-rays after incubation for 0-6 hr. The cells were incubated either on nutrient medium or salt agar between the treatments. Loss of reproductive ability and mutation to canavanine resistance were measured. When the X-ray exposure immediately followed UV-irradiation, the X-ray survival curves had the same slope irrespective of the pretreatment, while the X-ray mutation induction curves were changed from linear to linear quadratic with increasing UV fluence. Incubations up to about 3 hr on nutrient medium between the treatments led to synergism with respect to cell inactivation and antagonism with respect to mutation, but after 4-6 hr the two treatments acted independently. Incubation on salt agar did not cause any change in the survival curves, but there was a strong suppression of X-ray-induced mutation with increasing UV fluence. On the basis of these results, we suggest that mutation after combined UV and X-ray exposure is affected not only by the induction and suppression of DNA repair processes, but also by radiation-induced modifications of cell-cycle progression and changes in the expression of the mutant phenotype. Copyright 2004 Wiley-Liss, Inc.

Chemiexcitation of Melanin Derivatives Induces DNA Photoproducts Long after UV Exposure

PubMed Central

Premi, Sanjay; Wallisch, Silvia; Mano, Camila M.; Weiner, Adam B.; Bacchiocchi, Antonella; Wakamatsu, Kazumasa; Bechara, Etelvino J. H.; Halaban, Ruth; Douki, Thierry; Brash, Douglas E.

2015-01-01

Mutations in sunlight-induced melanoma arise from cyclobutane pyrimidine dimers (CPD), DNA photoproducts that are typically created picoseconds after an ultraviolet (UV) photon is absorbed at thymine or cytosine. Here we show that in melanocytes, CPD are generated for >3 hours after exposure to UVA, a major component of the radiation in sunlight and in tanning beds. These “dark CPD” constitute the majority of CPD and include the cytosine-containing CPD that initiate UV-signature C→T mutations. Dark CPD arise when UV-induced reactive oxygen and nitrogen species combine to excite an electron in fragments of the pigment melanin. This creates a quantum triplet state that has the energy of a UV photon but that induces CPD by energy transfer to DNA in a radiation-independent manner. Melanin may thus be carcinogenic as well as protective against cancer. These findings also validate the long-standing suggestion that chemically-generated excited electronic states are relevant to mammalian biology. PMID:25700512

UV irradiation-induced Raman spectra changes in lead silicate glasses

NASA Astrophysics Data System (ADS)

Jia, Hongzhi; Chen, Guanghui; Wang, Wencheng

2006-12-01

The Raman spectra for a series of lead silicate glasses with different PbO content before and after irradiation with different energy density by the frequency-quadrupled output of a Q-switched YAG laser (266 nm, 10 Hz repetition rate) were measured. The intensity of Pb-O band near 140 cm -1 in the Raman spectra decreases after UV irradiation and no new band appears in the Raman spectra. Exposed to the UV beam with high energy density (150 mJ/cm 2), although the total dose is smaller than the dose with low energy density (50 mJ/cm 2), the intensity of the 140 cm -1 band drops heavilier than exposed to the UV beam with low energy density. This shows that the UV irradiation can cause the broken of Pb-O bond in lead silicate glasses and the broken of Pb-O bond is related to the energy density of UV beam.

New mutations affecting induced mutagenesis in yeast.

PubMed

Lawrence, C W; Krauss, B R; Christensen, R B

1985-01-01

Previously isolated mutations in baker's yeast, Saccharomyces cerevisiae, that impair induced mutagenesis were all identified with the aid of tests that either exclusively or predominantly detect base-pair substitutions. To avoid this bias, we have screened 11 366 potentially mutant clones for UV-induced reversion of the frameshift allele, his4-38, and have identified 10 mutants that give much reduced yields of revertants. Complementation and recombination tests show that 6 of these carry mutations at the previously known REV1, REV1 and REV3 loci, while the remaining 4 define 3 new genes, REV4 (2 mutations), REV5 and REV6. The rev4 mutations are readily suppressed in many genetic backgrounds and, like the rev5 mutation, impart only a limited deficiency for induced mutagenesis: it is likely, therefore that the REV4+ and REV5+ gene functions are only remotely concerned with this process. The rev6 mutants have a more general deficiency, however, as well as marked sensitivity to UV and an increased spontaneous mutation rate, properties that suggest the REV6 gene is directly involved in mutation induction. The REV5 gene is located about 1 cM proximal to CYC1 on chromosome X.

iMARS--mutation analysis reporting software: an analysis of spontaneous cII mutation spectra.

PubMed

Morgan, Claire; Lewis, Paul D

2006-01-31

The sensitivity of any mutational assay is determined by the level at which spontaneous mutations occur in the corresponding untreated controls. Establishing the type and frequency at which mutations occur naturally within a test system is essential if one is to draw scientifically sound conclusions regarding chemically induced mutations. Currently, mutation-spectra analysis is laborious and time-consuming. Thus, we have developed iMARS, a comprehensive mutation-spectrum analysis package that utilises routinely used methodologies and visualisation tools. To demonstrate the use and capabilities of iMARS, we have analysed the distribution, types and sequence context of spontaneous base substitutions derived from the cII gene mutation assay in transgenic animals. Analysis of spontaneous mutation spectra revealed variation both within and between the transgenic rodent test systems Big Blue Mouse, MutaMouse and Big Blue Rat. The most common spontaneous base substitutions were G:C-->A:T transitions and G:C-->T:A transversions. All Big Blue Mouse spectra were significantly different from each other by distribution and nearly all by mutation type, whereas the converse was true for the other test systems. Twenty-eight mutation hotspots were observed across all spectra generally occurring in CG, GA/TC, GG and GC dinucleotides. A mutation hotspot at nucleotide 212 occurred at a higher frequency in MutaMouse and Big Blue Rat. In addition, CG dinucleotides were the most mutable in all spectra except two Big Blue Mouse spectra. Thus, spontaneous base-substitution spectra showed more variation in distribution, type and sequence context in Big Blue Mouse relative to spectra derived from MutaMouse and Big Blue Rat. The results of our analysis provide a baseline reference for mutation studies utilising the cII gene in transgenic rodent models. The potential differences in spontaneous base-substitution spectra should be considered when making comparisons between these test systems. The ease at which iMARS has allowed us to carry out an exhaustive investigation to assess mutation distribution, mutation type, strand bias, target sequences and motifs, as well as predict mutation hotspots provides us with a valuable tool in helping to distinguish true chemically induced hotspots from background mutations and gives a true reflection of mutation frequency.

Comparative studies on the lethal, mutagenic, and recombinogenic effects of ultraviolet -A, -B, -C, and visible light with and without 8-methoxypsoralen in Saccharomyces cerevisiae.

PubMed

Mondon, P; Shahin, M M

1992-05-01

Genetic effects of UV-A, UV-B, UV-C, and the combination of 8-methoxypsoralen (8-MOP) with UV-A or visible light were studied in the haploid strain XV185-14C and diploid strain D5 of Saccharomyces cerevisiae. The induction of his+, lys+, and hom+ reverse mutations was measured in strain XV185-14C. In strain D5 we measured the induction of genetically altered colonies, particularly twin spot colonies arising from a mitotic crossing-over. UV-C and UV-B induced point mutations at the three loci in the haploid strain and mitotic crossing-over and other genetic alterations in the diploid strain. UV-C was more mutagenic and recombinogenic than UV-B. UV-A or visible light alone did not induce genotoxic effects at the doses tested. However, UV-A plus 8-MOP produced lethal and mutagenic effects in the haploid strain XV185-14C, although mutagenic activity was less than that of UV-B. Visible light plus 8-MOP also induced genotoxic effects in strain XV185-14C. In the diploid strain D5, UV-A plus 8-MOP induced a higher frequency of genetic alterations than UV-B at comparative doses. Visible light plus 8-MOP was also genetically active in strain D5. The haploid strain was more sensitive to the lethal effects of UV-C, UV-B, UV-A, and impure visible light plus 8-MOP than the diploid strain.

The induction of mutation and recombination following UV irradiation during meiosis in Saccharomyces cerevisiae.

PubMed

Kelly, S L; Parry, J M

1983-03-01

Irradiation of yeast cultures with ultraviolet light at discrete stages during meiosis produces cyclic variations in sensitivity, i.e. cells are more sensitive to the lethal effects of UV light prior to entry into the meiotic DNA synthesis, and this corresponds to a peak of induction of point mutation. Cells become more resistant to both induced point mutation and lethality as they enter meiotic DNA synthesis, but become more sensitive again during spore formation. The induced level of intragenic recombination rises during the period of commitment to recombination to a level indistinguishable from the full meiotic level of spontaneous intragenic recombination. Induced reciprocal recombination remains above the spontaneous level up to the point of commitment to sporulation.

Mechanistic considerations on the wavelength-dependent variations of UVR genotoxicity and mutagenesis in skin: the discrimination of UVA-signature from UV-signature mutation.

PubMed

Ikehata, Hironobu

2018-05-31

Ultraviolet radiation (UVR) predominantly induces UV-signature mutations, C → T and CC → TT base substitutions at dipyrimidine sites, in the cellular and skin genome. I observed in our in vivo mutation studies of mouse skin that these UVR-specific mutations show a wavelength-dependent variation in their sequence-context preference. The C → T mutation occurs most frequently in the 5'-TCG-3' sequence regardless of the UVR wavelength, but is recovered more preferentially there as the wavelength increases, resulting in prominent occurrences exclusively in the TCG sequence in the UVA wavelength range, which I will designate as a "UVA signature" in this review. The preference of the UVB-induced C → T mutation for the sequence contexts shows a mixed pattern of UVC- and UVA-induced mutations, and a similar pattern is also observed for natural sunlight, in which UVB is the most genotoxic component. In addition, the CC → TT mutation hardly occurs at UVA1 wavelengths, although it is detected rarely but constantly in the UVC and UVB ranges. This wavelength-dependent variation in the sequence-context preference of the UVR-specific mutations could be explained by two different photochemical mechanisms of cyclobutane pyrimidine dimer (CPD) formation. The UV-signature mutations observed in the UVC and UVB ranges are known to be caused mainly by CPDs produced through the conventional singlet/triplet excitation of pyrimidine bases after the direct absorption of the UVC/UVB photon energy in those bases. On the other hand, a novel photochemical mechanism through the direct absorption of the UVR energy to double-stranded DNA, which is called "collective excitation", has been proposed for the UVA-induced CPD formation. The UVA photons directly absorbed by DNA produce CPDs with a sequence context preference different from that observed for CPDs caused by the UVC/UVB-mediated singlet/triplet excitation, causing CPD formation preferentially at thymine-containing dipyrimidine sites and probably also preferably at methyl CpG-associated dipyrimidine sites, which include the TCG sequence. In this review, I present a mechanistic consideration on the wavelength-dependent variation of the sequence context preference of the UVR-specific mutations and rationalize the proposition of the UVA-signature mutation, in addition to the UV-signature mutation.

PSO4: a novel gene involved in error-prone repair in Saccharomyces cerevisiae.

PubMed

Henriques, J A; Vicente, E J; Leandro da Silva, K V; Schenberg, A C

1989-09-01

The haploid xs9 mutant, originally selected for on the basis of a slight sensitivity to the lethal effect of X-rays, was found to be extremely sensitive to inactivation by 8-methoxypsoralen (8MOP) photoaddition, especially when cells are treated in the G2 phase of the cell cycle. As the xs9 mutation showed no allelism with any of the 3 known pso mutations, it was now given the name of pso4-1. Regarding inactivation, the pso4-1 mutant is also sensitive to mono- (HN1) or bi-functional (HN2) nitrogen mustards, it is slightly sensitive to 254 nm UV radiation (UV), and shows nearly normal sensitivity to 3-carbethoxypsoralen (3-CPs) photoaddition or methyl methanesulfonate (MMS). Regarding mutagenesis, the pso4-1 mutation completely blocks reverse and forward mutations induced by either 8MOP or 3CPs photoaddition, or by gamma-rays. In the cases of UV, HN1, HN2 or MMS treatments, while reversion induction is still completely abolished, forward mutagenesis is only partially inhibited for UV, HN1, or MMS, and it is unaffected for HN2. Besides severely inhibiting induced mutagenesis, the pso4-1 mutation was found to be semi-dominant, to block sporulation, to abolish the diploid resistance effect, and to block induced mitotic recombination, which indicates that the PSO4 gene is involved in a recombinational pathway of error-prone repair, comparable to the E. coli SOS repair pathway.

Beta HPV38 oncoproteins act with a hit-and-run mechanism in ultraviolet radiation-induced skin carcinogenesis in mice.

PubMed

Viarisio, Daniele; Müller-Decker, Karin; Accardi, Rosita; Robitaille, Alexis; Dürst, Matthias; Beer, Katrin; Jansen, Lars; Flechtenmacher, Christa; Bozza, Matthias; Harbottle, Richard; Voegele, Catherine; Ardin, Maude; Zavadil, Jiri; Caldeira, Sandra; Gissmann, Lutz; Tommasino, Massimo

2018-01-01

Cutaneous beta human papillomavirus (HPV) types are suspected to be involved, together with ultraviolet (UV) radiation, in the development of non-melanoma skin cancer (NMSC). Studies in in vitro and in vivo experimental models have highlighted the transforming properties of beta HPV E6 and E7 oncoproteins. However, epidemiological findings indicate that beta HPV types may be required only at an initial stage of carcinogenesis, and may become dispensable after full establishment of NMSC. Here, we further investigate the potential role of beta HPVs in NMSC using a Cre-loxP-based transgenic (Tg) mouse model that expresses beta HPV38 E6 and E7 oncogenes in the basal layer of the skin epidermis and is highly susceptible to UV-induced carcinogenesis. Using whole-exome sequencing, we show that, in contrast to WT animals, when exposed to chronic UV irradiation K14 HPV38 E6/E7 Tg mice accumulate a large number of UV-induced DNA mutations, which increase proportionally with the severity of the skin lesions. The mutation pattern detected in the Tg skin lesions closely resembles that detected in human NMSC, with the highest mutation rate in p53 and Notch genes. Using the Cre-lox recombination system, we observed that deletion of the viral oncogenes after development of UV-induced skin lesions did not affect the tumour growth. Together, these findings support the concept that beta HPV types act only at an initial stage of carcinogenesis, by potentiating the deleterious effects of UV radiation.

Beta HPV38 oncoproteins act with a hit-and-run mechanism in ultraviolet radiation-induced skin carcinogenesis in mice

PubMed Central

Müller-Decker, Karin; Accardi, Rosita; Flechtenmacher, Christa; Bozza, Matthias; Harbottle, Richard; Voegele, Catherine; Ardin, Maude; Zavadil, Jiri; Gissmann, Lutz

2018-01-01

Cutaneous beta human papillomavirus (HPV) types are suspected to be involved, together with ultraviolet (UV) radiation, in the development of non-melanoma skin cancer (NMSC). Studies in in vitro and in vivo experimental models have highlighted the transforming properties of beta HPV E6 and E7 oncoproteins. However, epidemiological findings indicate that beta HPV types may be required only at an initial stage of carcinogenesis, and may become dispensable after full establishment of NMSC. Here, we further investigate the potential role of beta HPVs in NMSC using a Cre-loxP-based transgenic (Tg) mouse model that expresses beta HPV38 E6 and E7 oncogenes in the basal layer of the skin epidermis and is highly susceptible to UV-induced carcinogenesis. Using whole-exome sequencing, we show that, in contrast to WT animals, when exposed to chronic UV irradiation K14 HPV38 E6/E7 Tg mice accumulate a large number of UV-induced DNA mutations, which increase proportionally with the severity of the skin lesions. The mutation pattern detected in the Tg skin lesions closely resembles that detected in human NMSC, with the highest mutation rate in p53 and Notch genes. Using the Cre-lox recombination system, we observed that deletion of the viral oncogenes after development of UV-induced skin lesions did not affect the tumour growth. Together, these findings support the concept that beta HPV types act only at an initial stage of carcinogenesis, by potentiating the deleterious effects of UV radiation. PMID:29324843

The timing of UV mutagenesis in yeast: a pedigree analysis of induced recessive mutation.

PubMed

James, A P; Kilbey, B J

1977-10-01

The mechanism of UV-induced mutation in eukaryotes was studied in individual yeast cells by a procedure that combined pedigree analysis and tetrad analysis. The technique involved the induction of recessive lethals and semilethals in G1 diploid cells. Induced frequencies were 25 and 61 percent at survival levels of 90 and 77 percent, respectively. No evidence of gross chromosome aberrations was detected. Recessive mutations that affect only one strand or that affect both strands of the DNA molecule are induced much at random among a population of cells, and both types can occur within the same cell. However, the data confirm that two-strand mutations are in the majority after a low level of irradiation. The simplest explanation involves a mechanism whereby most mutations are fixed in both strands prior to the first round of post-irradiation DNA replication. The recessive mutational consequences of irradiation are exhausted at the conclusion of the first post-irradiation cell division, although dominant-lethal sectoring continues at a high level through the second post-irradiation division. It is concluded that pyrimidine dimers that persist to the second round of DNA replication are rare or ineffective.

Induction of homologous recombination in Saccharomyces cerevisiae.

PubMed

Simon, J R; Moore, P D

1988-09-01

We have investigated the effects of UV irradiation of Saccharomyces cerevisiae in order to distinguish whether UV-induced recombination results from the induction of enzymes required for homologous recombination, or the production of substrate sites for recombination containing regions of DNA damage. We utilized split-dose experiments to investigate the induction of proteins required for survival, gene conversion, and mutation in a diploid strain of S. cerevisiae. We demonstrate that inducing doses of UV irradiation followed by a 6 h period of incubation render the cells resistant to challenge doses of UV irradiation. The effects of inducing and challenge doses of UV irradiation upon interchromosomal gene conversion and mutation are strictly additive. Using the yeast URA3 gene cloned in non-replicating single- and double-stranded plasmid vectors that integrate into chromosomal genes upon transformation, we show that UV irradiation of haploid yeast cells and homologous plasmid DNA sequences each stimulate homologous recombination approximately two-fold, and that these effects are additive. Non-specific DNA damage has little effect on the stimulation of homologous recombination, as shown by studies in which UV-irradiated heterologous DNA was included in transformation/recombination experiments. We further demonstrate that the effect of competing single- and double-stranded heterologous DNA sequences differs in UV-irradiated and unirradiated cells, suggesting an induction of recombinational machinery in UV-irradiated S. cerevisiae cells.

The Mechanism of Nucleotide Excision Repair-Mediated UV-Induced Mutagenesis in Nonproliferating Cells

PubMed Central

Kozmin, Stanislav G.; Jinks-Robertson, Sue

2013-01-01

Following the irradiation of nondividing yeast cells with ultraviolet (UV) light, most induced mutations are inherited by both daughter cells, indicating that complementary changes are introduced into both strands of duplex DNA prior to replication. Early analyses demonstrated that such two-strand mutations depend on functional nucleotide excision repair (NER), but the molecular mechanism of this unique type of mutagenesis has not been further explored. In the experiments reported here, an ade2 adeX colony-color system was used to examine the genetic control of UV-induced mutagenesis in nondividing cultures of Saccharomyces cerevisiae. We confirmed a strong suppression of two-strand mutagenesis in NER-deficient backgrounds and demonstrated that neither mismatch repair nor interstrand crosslink repair affects the production of these mutations. By contrast, proteins involved in the error-prone bypass of DNA damage (Rev3, Rev1, PCNA, Rad18, Pol32, and Rad5) and in the early steps of the DNA-damage checkpoint response (Rad17, Mec3, Ddc1, Mec1, and Rad9) were required for the production of two-strand mutations. There was no involvement, however, for the Pol η translesion synthesis DNA polymerase, the Mms2-Ubc13 postreplication repair complex, downstream DNA-damage checkpoint factors (Rad53, Chk1, and Dun1), or the Exo1 exonuclease. Our data support models in which UV-induced mutagenesis in nondividing cells occurs during the Pol ζ-dependent filling of lesion-containing, NER-generated gaps. The requirement for specific DNA-damage checkpoint proteins suggests roles in recruiting and/or activating factors required to fill such gaps. PMID:23307894

Stratospheric ozone loss, ultraviolet effects and action spectroscopy

NASA Astrophysics Data System (ADS)

Coohill, Thomas P.

The major effect of stratospheric ozone loss will be an increase in the amount of ultraviolet radiation reaching the ground. This increase will be entirely contained within the UV-B (290-320nm). How this will impact life on Earth will be determined by the UV-B photobiology of exposed organisms, including humans. One of the analytical methods useful in estimating these effects is Action Spectroscopy (biological effect as a function of wavelength). Carefully constructed action spectra will allow us to partially predict the increase in bio-effect due to additional UV exposure. What effect this has on the organism and the system in which the organism resides is of paramount importance. Suitable action spectra already exist for human skin cancer, human cell mutation and killing, and for one immune response. Comprehensive and widely applicable action spectra for terrestrial and aquatic plant responses are being generated but are not yet suitable for extensive analysis. There is little data available for animals, other than those experiments completed in the laboratory as model systems for human studies. Some polychromatic action spectra have proven useful in determining the possible impact of ozone loss on biological systems. The pitfalls and limits of this approach will be addressed.

Newly identified CHO ERCC3/XPB mutations and phenotype characterization

PubMed Central

Rybanská, Ivana; Gurský, Ján; Fašková, Miriam; Salazar, Edmund P.; Kimlíčková-Polakovičová, Erika; Kleibl, Karol; Thompson, Larry H.; Piršel, Miroslav

2010-01-01

Nucleotide excision repair (NER) is a complex multistage process involving many interacting gene products to repair a wide range of DNA lesions. Genetic defects in NER cause human hereditary diseases including xeroderma pigmentosum (XP), Cockayne syndrome (CS), trichothiodystrophy and a combined XP/CS overlapping symptom. One key gene product associated with all these disorders is the excision repair cross-complementing 3/xeroderma pigmentosum B (ERCC3/XPB) DNA helicase, a subunit of the transcription factor IIH complex. ERCC3 is involved in initiation of basal transcription and global genome repair as well as in transcription-coupled repair (TCR). The hamster ERCC3 gene shows high degree of homology with the human ERCC3/XPB gene. We identified new mutations in the Chinese hamster ovary cell ERCC3 gene and characterized the role of hamster ERCC3 protein in DNA repair of ultraviolet (UV)-induced and oxidative DNA damage. All but one newly described mutations are located in the protein C-terminal region around the last intron–exon boundary. Due to protein truncations or frameshifts, they lack amino acid Ser751, phosphorylation of which prevents the 5′ incision of the UV-induced lesion during NER. Thus, despite the various locations of the mutations, their phenotypes are similar. All ercc3 mutants are extremely sensitive to UV-C light and lack recovery of RNA synthesis (RRS), confirming a defect in TCR of UV-induced damage. Their limited global genome NER capacity averages ∼8%. We detected modest sensitivity of ercc3 mutants to the photosensitizer Ro19-8022, which primarily introduces 8-oxoguanine lesions into DNA. Ro19-8022-induced damage interfered with RRS, and some of the ercc3 mutants had delayed kinetics. All ercc3 mutants showed efficient base excision repair (BER). Thus, the positions of the mutations have no effect on the sensitivity to, and repair of, Ro19-8022-induced DNA damage, suggesting that the ERCC3 protein is not involved in BER. PMID:19942596

Mutagenesis during plant responses to UVB radiation.

PubMed

Holá, M; Vágnerová, R; Angelis, K J

2015-08-01

We tested an idea that induced mutagenesis due to unrepaired DNA lesions, here the UV photoproducts, underlies the impact of UVB irradiation on plant phenotype. For this purpose we used protonemal culture of the moss Physcomitrella patens with 50% of apical cells, which mimics actively growing tissue, the most vulnerable stage for the induction of mutations. We measured the UVB mutation rate of various moss lines with defects in DNA repair (pplig4, ppku70, pprad50, ppmre11), and in selected clones resistant to 2-Fluoroadenine, which were mutated in the adenosine phosphotrasferase gene (APT), we analysed induced mutations by sequencing. In parallel we followed DNA break repair and removal of cyclobutane pyrimidine dimers with a half-life τ = 4 h 14 min determined by comet assay combined with UV dimer specific T4 endonuclease V. We show that UVB induces massive, sequence specific, error-prone bypass repair that is responsible for a high mutation rate owing to relatively slow, though error-free, removal of photoproducts by nucleotide excision repair (NER). Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Are there mechanistic differences between ultraviolet and visible radiation induced skin pigmentation?

PubMed

Ramasubramaniam, Rajagopal; Roy, Arindam; Sharma, Bharati; Nagalakshmi, Surendra

2011-12-01

Most of the studies on sunlight-induced pigmentation of skin are mainly focused on ultraviolet (UV) radiation-induced pigmentation and ways to prevent it. Recent studies have shown that the visible component of sunlight can also cause significant skin pigmentation. In the current study, the extent of pigmentation induced by UV and visible regions of sunlight in subjects with Fitzpatrick skin type IV-V was measured and compared with pigmentation induced by total sunlight. The immediate pigment darkening (IPD) induced by the visible fraction of sunlight is not significantly different from that induced by the UV fraction. However, the persistent pigment darkening (PPD) induced by visible fraction of sunlight in significantly lower than that induced by the UV fraction. The dose responses of IPD induced by UV, visible light and total sunlight suggest that both UV and visible light interact with the same precursor although UV is 25 times more efficient in inducing pigmentation per J cm(-2) of irradiation compared to visible radiation. The measured diffused reflection spectra and decay kinetics of UV and visible radiation-induced pigmentation are very similar, indicating that the nature of the transient and persistent species involved in both the processes are also likely to be same.

A novel P53/POMC/Gαs/SASH1 autoregulatory feedback loop activates mutated SASH1 to cause pathologic hyperpigmentation.

PubMed

Zhou, Ding'an; Wei, Zhiyun; Kuang, Zhongshu; Luo, Huangchao; Ma, Jiangshu; Zeng, Xing; Wang, Ke; Liu, Beizhong; Gong, Fang; Wang, Jing; Lei, Shanchuan; Wang, Dongsheng; Zeng, Jiawei; Wang, Teng; He, Yong; Yuan, Yongqiang; Dai, Hongying; He, Lin; Xing, Qinghe

2017-04-01

p53-Transcriptional-regulated proteins interact with a large number of other signal transduction pathways in the cell, and a number of positive and negative autoregulatory feedback loops act upon the p53 response. P53 directly controls the POMC/α-MSH productions induced by ultraviolet (UV) and is associated with UV-independent pathological pigmentation. When identifying the causative gene of dyschromatosis universalis hereditaria (DUH), we found three mutations encoding amino acid substitutions in the gene SAM and SH3 domain containing 1 (SASH1), and SASH1 was associated with guanine nucleotide-binding protein subunit-alpha isoforms short (Gαs). However, the pathological gene and pathological mechanism of DUH remain unknown for about 90 years. We demonstrate that SASH1 is physiologically induced by p53 upon UV stimulation and SASH and p53 is reciprocally induced at physiological and pathophysiological conditions. SASH1 is regulated by a novel p53/POMC/α-MSH/Gαs/SASH1 cascade to mediate melanogenesis. A novel p53/POMC/Gαs/SASH1 autoregulatory positive feedback loop is regulated by SASH1 mutations to induce pathological hyperpigmentation phenotype. Our study demonstrates that a novel p53/POMC/Gαs/SASH1 autoregulatory positive feedback loop is regulated by SASH1 mutations to induce pathological hyperpigmentation phenotype. © 2016 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

NanoTIO(2) (UV-Titan) does not induce ESTR mutations in the germline of prenatally exposed female mice.

PubMed

Boisen, Anne Mette Zenner; Shipley, Thomas; Jackson, Petra; Hougaard, Karin Sørig; Wallin, Håkan; Yauk, Carole L; Vogel, Ulla

2012-06-01

Particulate air pollution has been linked to an increased risk of cardiovascular disease and cancer. Animal studies have shown that inhalation of air particulates induces mutations in the male germline. Expanded simple tandem repeat (ESTR) loci in mice are sensitive markers of mutagenic effects on male germ cells resulting from environmental exposures; however, female germ cells have received little attention. Oocytes may be vulnerable during stages of active cell division (e.g., during fetal development). Accordingly, an increase in germline ESTR mutations in female mice prenatally exposed to radiation has previously been reported. Here we investigate the effects of nanoparticles on the female germline. Since pulmonary exposure to nanosized titanium dioxide (nanoTiO(2)) produces a long-lasting inflammatory response in mice, it was chosen for the present study. Pregnant C57BL/6 mice were exposed by whole-body inhalation to the nanoTiO(2) UV-Titan L181 (~42.4 mg UV-Titan/m(3)) or filtered clean air on gestation days (GD) 8-18. Female C57BL/6 F1 offspring were raised to maturity and mated with unexposed CBA males. The F2 descendents were collected and ESTR germline mutation rates in this generation were estimated from full pedigrees (mother, father, offspring) of F1 female mice (192 UV-Titan-exposed F2 offspring and 164 F2 controls). ESTR mutation rates of 0.029 (maternal allele) and 0.047 (paternal allele) in UV-Titan-exposed F2 offspring were not statistically different from those of F2 controls: 0.037 (maternal allele) and 0.061 (paternal allele). We found no evidence for increased ESTR mutation rates in F1 females exposed in utero to UV-Titan nanoparticles from GD8-18 relative to control females.

Abnormal ultraviolet mutagenic spectrum in plasmid DNA replicated in cultured fibroblasts from a patient with the skin cancer-prone disease, xeroderma pigmentosum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seetharam, S.; Protic-Sabljic, M.; Seidman, M.M.

1987-12-01

A shuttle vector plasmid, pZ189, was utilized to assess the types of mutations that cells from a patient with xeroderma pigmentosum, complementation group D, introduce into ultraviolet (UV) damaged, replicating DNA. Patients with xeroderma pigmentosum have clinical and cellular UV hypersensitivity, increased frequency of sun-induced skin cancer, and deficient DNA repair. In comparison to UV-treated pZ189 replicated in DNA repair-proficient cells, there were fewer surviving plasmids, a higher frequency of plasmids with mutations, fewer plasmids with two or more mutations in the marker gene, and a new mutagenic hotspot. The major type of base substitution mutation was the G:C tomore » A:T transition with both cell lines. These results, together with similar findings published earlier with cells from a xeroderma pigmentosum patient in complementation group A, suggest that isolated G:C to A:T somatic mutations may be particularly important in generation of human skin cancer by UV radiation.« less

FANCJ localization by mismatch repair is vital to maintain genomic integrity after UV irradiation.

PubMed

Guillemette, Shawna; Branagan, Amy; Peng, Min; Dhruva, Aashana; Schärer, Orlando D; Cantor, Sharon B

2014-02-01

Nucleotide excision repair (NER) is critical for the repair of DNA lesions induced by UV radiation, but its contribution in replicating cells is less clear. Here, we show that dual incision by NER endonucleases, including XPF and XPG, promotes the S-phase accumulation of the BRCA1 and Fanconi anemia-associated DNA helicase FANCJ to sites of UV-induced damage. FANCJ promotes replication protein A phosphorylation and the arrest of DNA synthesis following UV irradiation. Interaction defective mutants of FANCJ reveal that BRCA1 binding is not required for FANCJ localization, whereas interaction with the mismatch repair (MMR) protein MLH1 is essential. Correspondingly, we find that FANCJ, its direct interaction with MLH1, and the MMR protein MSH2 function in a common pathway in response to UV irradiation. FANCJ-deficient cells are not sensitive to killing by UV irradiation, yet we find that DNA mutations are significantly enhanced. Thus, we considered that FANCJ deficiency could be associated with skin cancer. Along these lines, in melanoma we found several somatic mutations in FANCJ, some of which were previously identified in hereditary breast cancer and Fanconi anemia. Given that, mutations in XPF can also lead to Fanconi anemia, we propose collaborations between Fanconi anemia, NER, and MMR are necessary to initiate checkpoint activation in replicating human cells to limit genomic instability.

UV light-induced survival response in a highly radiation-resistant isolate of the Moraxella-acinetobacter group

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keller, L.C.; Thompson, T.L.; Maxcy, R.B.

1982-02-01

A highly radiation-resistant member of the Moraxella-Acinetobacter group, isolate 4, obtained from meat, was studied to determine the effect of preexposure to UV radiation on subsequent UV light resistance. Cultures that were preexposed to UV light and incubated for a short time in plate count broth exhibited increased survival of a UV light challenge dose. This response was inhibited in the presence of chloramphenicol. Frequencies of mutation to streptomycin, trimethoprim, and sulfanilamide resistance remained the same after the induction of this survival response and were not altered by treatment with mutagens, with the exception of mutation to streptomycin resistance aftermore » ..gamma..-irradiation or nitrosoguanidine or methyl methane sulfonate treatment. The results indicated that isolate 4 has a UV light-inducible UV light resistance mechanism which is not associated with increased mutagenesis. The characteristics of the radiation resistance response in this organism are similar to those of certain other common food contaminants. Therefore, considered as part of the total microflora of meat, isolate 4 and the other radiation-resistant Moraxella-Acinetobacter isolates should not pose unique problems in a proposed radappertizaton process.« less

Defect of Fe-S cluster binding by DNA polymerase δ in yeast suppresses UV-induced mutagenesis, but enhances DNA polymerase ζ - dependent spontaneous mutagenesis.

PubMed

Stepchenkova, E I; Tarakhovskaya, E R; Siebler, H M; Pavlov, Y I

2017-01-01

Eukaryotic genomes are duplicated by a complex machinery, utilizing high fidelity replicative B-family DNA polymerases (pols) α, δ and ε. Specialized error-prone pol ζ, the fourth B-family member, is recruited when DNA synthesis by the accurate trio is impeded by replication stress or DNA damage. The damage tolerance mechanism dependent on pol ζ prevents DNA/genome instability and cell death at the expense of increased mutation rates. The pol switches occurring during this specialized replication are not fully understood. The loss of pol ζ results in the absence of induced mutagenesis and suppression of spontaneous mutagenesis. Disruption of the Fe-S cluster motif that abolish the interaction of the C-terminal domain (CTD) of the catalytic subunit of pol ζ with its accessory subunits, which are shared with pol δ, leads to a similar defect in induced mutagenesis. Intriguingly, the pol3-13 mutation that affects the Fe-S cluster in the CTD of the catalytic subunit of pol δ also leads to defective induced mutagenesis, suggesting the possibility that Fe-S clusters are essential for the pol switches during replication of damaged DNA. We confirmed that yeast strains with the pol3-13 mutation are UV-sensitive and defective in UV-induced mutagenesis. However, they have increased spontaneous mutation rates. We found that this increase is dependent on functional pol ζ. In the pol3-13 mutant strain with defective pol δ, there is a sharp increase in transversions and complex mutations, which require functional pol ζ, and an increase in the occurrence of large deletions, whose size is controlled by pol ζ. Therefore, the pol3-13 mutation abrogates pol ζ-dependent induced mutagenesis, but allows for pol ζ recruitment for the generation of spontaneous mutations and prevention of larger deletions. These results reveal differential control of the two major types of pol ζ-dependent mutagenesis by the Fe-S cluster present in replicative pol δ. Copyright © 2016 Elsevier B.V. All rights reserved.

Characterizing the weathering induced changes in optical performance and properties of poly(ethylene-terephthalate) via MaPd:RTS spectroscopy

NASA Astrophysics Data System (ADS)

Gordon, Devin A.; DeNoyer, Lin; Meyer, Corey W.; Sweet, Noah W.; Burns, David M.; Bruckman, Laura S.; French, Roger H.

2017-08-01

Poly(ethylene-terephthalate) (PET) film is widely used in photovoltaic module backsheets for its dielectric break- down strength, and in applications requiring high optical clarity for its high transmission in the visible region. However, PET degrades and loses optical clarity under exposure to ultraviolet (UV) irradiance, heat, and moisture. Stabilizers are often included in PET formulation to increase its longevity; however, even these are subject to degradation and further reduce optical clarity. To study the weathering induced changes in the optical properties in PET films, samples of a UV-stabilized grade of PET were exposed to heat, moisture, and UV irradiance as prescribed by ASTM-G154 Cycle 4 for 168 hour time intervals. UV-Vis reflection and transmission spectra were collected via Multi-Angle, Polarization-Dependent, Reflection, Transmission, and Scattering (MaPd:RTS) spectroscopy after each exposure interval. The resulting spectra were used to calculate the complex index of refraction throughout the UV-Vis spectral region via an iterative optimization process based upon the Fresnel equations. The index of refraction and extinction coefficient were found to vary throughout the UV-Vis region with time under exposure. The spectra were also used to investigate changes in light scattering behavior with increasing exposure time. The intensity of scattered light was found to increase at higher angles with time under exposure.

A novel class of Saccharomyces cerevisiae mutants specifically UV-sensitive to "petite" induction.

PubMed

Moustacchi, E; Perlman, P S; Mahler, H R

1976-11-17

A mutant of Saccharomyces cerevisiae has been isolated which, though exhibiting a normal response to nuclear genetic damage by ultraviolet light (UV), is more sensitive than its wild type specifically in the production of the cytoplasmic (rho-) mutation by this agent. Some of the features of this mutation which has been designated uvsrho 5 are: i) The mutation is recessive, it exhibits a Mendelian, and hence presumably nuclear, pattern of segregation, but manifests its effects specifically and pleiotropically on mitochondrial functions. ii) Mutant cells resemble their wild type parents in a) growth characteristics on glucose; b) in their UV induced dose response to lethality or nuclear mutation and c) the ability of their mitochondrial genome, upon mating with appropriate testers, of transmitting and recombining various markers, albeit with enhanced efficiency. Similarly, d) they are able to modulate the expression of mitochondrial mutagenesis by ethidium bromide. Thus their mitochondrial DNA appears genetically as competent as that of the wild type. iii) Mutant cells differ from their wild type parents in a) growth characteristics on glycerol; b) susceptibility to induction of the mitochondrial (rho-) mutation by various mutagens, in that the rate of spontaneous mutation is slightly and that by UV is significantly enhanced, whild that by ethidium bromide is greatly diminished. Conversely, c) modulating influences resulting in the repair of initial damage are diminished fro UV and stimulated in the case of Berenil. iv) The amount of mitochondrial DNA per cell appears elevated in the mutant, relative to wild type, and its rate of degradation subsequent to a mutagenic exposure to either UV or ethidium bromide is diminished. v) A self-consistent scheme to account for this and all other information so far available for the induction and modulation of the (rho-) mutation is presented. In a previous study it was shown that some nuclear mutants of Saccharomyces cerevisiae, more sensitive to lethal damage induced by ultraviolet light (rad) than their parent wild type (RAD), also exhibit a concomitant modification in sensitivity to both nuclear and cytoplasmic genetic damage (Moustacchi, 1971). However, another class of rad mutants respond to the induction of the cytoplasmic "petite" also designated as rho- (or rho-) mutation by UV in a manner indistinguishable from that of the RAD strain. One possible interpretation of this last observation is that some of the steps in the expression of the UV damage on mitochondrial (mt)DNA may be governed by other nuclear and cytoplasmic genetic determinants, the products of which may then act specifically on mitochondrial lesions. If this assumption is correct, it should be possible to find mutants with a normal response to nuclear damage but specifically UV-sensitive towards induction of (rho-)...

Abnormal, Error-Prone Bypass of Photoproducts by Xeroderma Pigmentosum Variant Cell Extracts Results in Extreme Strand Bias for the Kinds of Mutations Induced by UV Light

PubMed Central

McGregor, W. Glenn; Wei, Dong; Maher, Veronica M.; McCormick, J. Justin

1999-01-01

Xeroderma pigmentosum (XP) is a rare genetic disease characterized by a greatly increased susceptibility to sunlight-induced skin cancer. Cells from the majority of patients are defective in nucleotide excision repair. However, cells from one set of patients, XP variants, exhibit normal repair but are abnormally slow in replicating DNA containing UV photoproducts. The frequency of UV radiation-induced mutations in the XP variant cells is significantly higher than that in normal human cells. Furthermore, the kinds of UV-induced mutations differ very significantly from normal. Instead of transitions, mainly C→T, 30% of the base substitutions consist of C→A transversions, all arising from photoproducts located in one strand. Mutations involving cytosine in the other strand are almost all C→T transitions. Forty-five percent of the substitutions involve thymine, and the majority are transversions. To test the hypothesis that the UV hypermutability and the abnormal spectrum of mutations result from abnormal bypass of photoproducts in DNA, we compared extracts from XP variant cells with those from HeLa cells and a fibroblast cell strain, MSU-1.2, for the ability to replicate a UV-irradiated form I M13 phage. The M13 template contains a simian virus 40 origin of replication located directly to the left or to the right of the target gene, lacZα, so that the template for the leading and lagging strands of DNA replication is defined. Reduction of replication to ∼37% of the control value required only 1 photoproduct per template for XP variant cell extracts, but ∼2.2 photoproducts for HeLa or MSU-1.2 cell extracts. The frequency of mutants induced was four times higher with XP variant cell extracts than with HeLa or MSU-1.2 cell extracts. With XP variant cell extracts, the proportion of C→A transversions reached as high as 43% with either M13 template and arose from photoproducts located in the template for leading-strand synthesis; with HeLa or MSU-1.2 cell extracts, this value was only 5%, and these arose from photoproducts in either strand. With the XP variant extracts, 26% of the substitutions involved thymine, and virtually all were T→A transversions. Sequence analysis of the coding region of the catalytic subunit of DNA polymerase delta in XP variant cell lines revealed two polymorphisms, but these do not account for the reduced bypass fidelity. Our data indicate that the UV hypermutability of XP variant cells results from reduced bypass fidelity and that unlike for normal cells, bypass of photoproducts involving cytosine in the template for the leading strand differs significantly from that of photoproducts in the lagging strand. PMID:9858539

MHY1485 ameliorates UV-induced skin cell damages via activating mTOR-Nrf2 signaling.

PubMed

Yang, Bo; Xu, Qiu-Yun; Guo, Chun-Yan; Huang, Jin-Wen; Wang, Shu-Mei; Li, Yong-Mei; Tu, Ying; He, Li; Bi, Zhi-Gang; Ji, Chao; Cheng, Bo

2017-02-21

Ultra Violet (UV)-caused skin cell damage is a main cause of skin cancer. Here, we studied the activity of MHY1485, a mTOR activator, in UV-treated skin cells. In primary human skin keratinocytes, HaCaT keratinocytes and human skin fibroblasts, MHY1485 ameliorated UV-induced cell death and apoptosis. mTOR activation is required for MHY1485-induced above cytoprotective actions. mTOR kinase inhibitors (OSI-027, AZD-8055 and AZD-2014) or mTOR shRNA knockdown almost abolished MHY1485-induced cytoprotection. Further, MHY1485 treatment in skin cells activated mTOR downstream NF-E2-related factor 2 (Nrf2) signaling, causing Nrf2 Ser-40 phosphorylation, stabilization/upregulation and nuclear translocation, as well as mRNA expression of Nrf2-dictated genes. Contrarily, Nrf2 knockdown or S40T mutation almost nullified MHY1485-induced cytoprotection. MHY1485 suppressed UV-induced reactive oxygen species production and DNA single strand breaks in skin keratinocytes and fibroblasts. Together, we conclude that MHY1485 inhibits UV-induced skin cell damages via activating mTOR-Nrf2 signaling.

Saccharomyces cerevisiae mutants with enhanced induced mutation and altered mitotic gene conversion.

PubMed

Ivanov, E L; Kovaltzova, S V; Korolev, V G

1989-08-01

We have developed a method to isolate yeast (Saccharomyces cerevisiae) mutants with enhanced induced mutagenesis based on nitrous acid-induced reversion of the ade2-42 allele. Six mutants have been isolated and designated him (high induced mutagenesis), and 4 of them were studied in more detail. The him mutants displayed enhanced reversion of the ade2-42 allele, either spontaneous or induced by nitrous acid, UV light, and the base analog 6-N-hydroxylaminopurine, but not by gamma-irradiation. It is worth noting that the him mutants turned out not to be sensitive to the lethal effects of the mutagens used. The enhancement in mutation induced by nitrous acid, UV light, and 6-N-hydroxylaminopurine has been confirmed in a forward-mutation assay (induction of mutations in the ADE1, ADE2 genes). The latter agent revealed the most apparent differences between the him mutants and the wild-type strain and was, therefore, chosen for the genetic analysis of mutants, him mutations analyzed behaved as a single Mendelian trait; complementation tests indicated 3 complementation groups (HIM1, HIM2, and HIM3), each containing 1 mutant allele. Uracil-DNA glycosylase activity was determined in crude cell extracts, and no significant differences between the wild-type and him strains were detected. Spontaneous mitotic gene conversion at the ADE2 locus is altered in him1 strains, either increased or decreased, depending on the particular heteroallelic combination. Genetic evidence strongly suggests him mutations to be involved in a process of mismatch correction of molecular heteroduplexes.

Fungal Gene Mutation Analysis Elucidating Photoselective Enhancement of UV-C Disinfection Efficiency Toward Spoilage Agents on Fruit Surface.

PubMed

Zhu, Pinkuan; Li, Qianwen; Azad, Sepideh M; Qi, Yu; Wang, Yiwen; Jiang, Yina; Xu, Ling

2018-01-01

Short-wave ultraviolet (UV-C) treatment represents a potent, clean and safe substitute to chemical sanitizers for fresh fruit preservation. However, the dosage requirement for microbial disinfection may have negative effects on fruit quality. In this study, UV-C was found to be more efficient in killing spores of Botrytis cinerea in dark and red light conditions when compared to white and blue light. Loss of the blue light receptor gene Bcwcl1 , a homolog of wc-1 in Neurospora crassa , led to hypersensitivity to UV-C in all light conditions tested. The expression of Bcuve1 and Bcphr1 , which encode UV-damage endonuclease and photolyase, respectively, were strongly induced by white and blue light in a Bcwcl1 -dependent manner. Gene mutation analyses of Bcuve1 and Bcphr1 indicated that they synergistically contribute to survival after UV-C treatment. In vivo assays showed that UV-C (1.0 kJ/m 2 ) abolished decay in drop-inoculated fruit only if the UV-C treatment was followed by a dark period or red light, while in contrast, typical decay appeared on UV-C irradiated fruits exposed to white or blue light. In summary, blue light enhances UV-C resistance in B. cinerea by inducing expression of the UV damage repair-related enzymes, while the efficiency of UV-C application for fruit surface disinfection can be enhanced in dark or red light conditions; these principles seem to be well conserved among postharvest fungal pathogens.

[Intragenic mitotic recombination induced by ultraviolet and gamma rays in radiosensitive mutants of Saccharomyces cerevisiae yeasts].

PubMed

Zakharov, I A; Kasinova, G V; Koval'tsova, S V

1983-01-01

The effect of UV- and gamma-irradiation on the survival and intragenic mitotic recombination (gene conversion) of 5 radiosensitive mutants was studied in comparison with the wild type. The level of spontaneous conversion was similar for RAD, rad2 and rad15, mutations xrs2 and xrs4 increasing and rad54 significantly decreasing it. The frequency of conversion induced by UV-light was greater in rad2, rad15 and xrs2 mutants and lower in xrs4, as compared to RAD. Gamma-irradiation caused induction of gene conversion with an equal frequency in RAD, rad2, rad15. Xrs2 and xrs4 mutations slightly decreased gamma-induced conversion. In rad54 mutant, UV-and gamma-induced conversion was practically absent. In the wild type yeast, a diploid strain is more resistant than a haploid, whereas in rad54 a diploid strain has the same or an increased sensitivity, as compared to a haploid strain (the "inverse ploidy effect"). This effect and also the block of induced mitotic recombination caused by rad54 indicate the presence in the yeast Saccharomyces cerevisiae of repair pathways of UV- and gamma-induced damages acting in diploid cells and realised by recombination. The data obtained as a result of many years' investigation of genetic effects in radiosensitive mutants of yeast are summarised and considered.

Gremlin inhibits UV-induced skin cell damages via activating VEGFR2-Nrf2 signaling

PubMed Central

Xu, Qiu-yun; Zhang, Jing; Lin, Meng-ting; Tu, Ying; He, Li; Bi, Zhi-gang; Cheng, Bo

2016-01-01

Ultra Violet (UV) radiation induces reactive oxygen species (ROS) production, DNA oxidation and single strand breaks (SSBs), which will eventually lead to skin cell damages or even skin cancer. Here, we tested the potential activity of gremlin, a novel vascular endothelial growth factor (VEGF) receptor 2 (VEGFR2) agonist, against UV-induced skin cell damages. We show that gremlin activated VEGFR2 and significantly inhibited UV-induced death and apoptosis of skin keratinocytes and fibroblasts. Pharmacological inhibition or shRNA-mediated knockdown of VEGFR2 almost abolished gremlin-mediated cytoprotection against UV in the skin cells. Further studies showed that gremlin activated VEGFR2 downstream NF-E2-related factor 2 (Nrf2) signaling, which appeared required for subsequent skin cell protection. Nrf2 shRNA knockdown or S40T dominant negative mutation largely inhibited gremlin-mediated skin cell protection against UV. At last, we show that gremlin dramatically inhibited UV-induced ROS production and DNA SSB formation in skin keratinocytes and fibroblasts. We conclude that gremlin protects skin cells from UV damages via activating VEGFR2-Nrf2 signaling. Gremlin could be further tested as a novel anti-UV skin protectant. PMID:27713170

Gremlin inhibits UV-induced skin cell damages via activating VEGFR2-Nrf2 signaling.

PubMed

Ji, Chao; Huang, Jin-Wen; Xu, Qiu-Yun; Zhang, Jing; Lin, Meng-Ting; Tu, Ying; He, Li; Bi, Zhi-Gang; Cheng, Bo

2016-12-20

Ultra Violet (UV) radiation induces reactive oxygen species (ROS) production, DNA oxidation and single strand breaks (SSBs), which will eventually lead to skin cell damages or even skin cancer. Here, we tested the potential activity of gremlin, a novel vascular endothelial growth factor (VEGF) receptor 2 (VEGFR2) agonist, against UV-induced skin cell damages. We show that gremlin activated VEGFR2 and significantly inhibited UV-induced death and apoptosis of skin keratinocytes and fibroblasts. Pharmacological inhibition or shRNA-mediated knockdown of VEGFR2 almost abolished gremlin-mediated cytoprotection against UV in the skin cells. Further studies showed that gremlin activated VEGFR2 downstream NF-E2-related factor 2 (Nrf2) signaling, which appeared required for subsequent skin cell protection. Nrf2 shRNA knockdown or S40T dominant negative mutation largely inhibited gremlin-mediated skin cell protection against UV. At last, we show that gremlin dramatically inhibited UV-induced ROS production and DNA SSB formation in skin keratinocytes and fibroblasts. We conclude that gremlin protects skin cells from UV damages via activating VEGFR2-Nrf2 signaling. Gremlin could be further tested as a novel anti-UV skin protectant.

DNA repair properties of Escherichia coli tif-1, recAo281 and lexA1 strains deficient in single-strand DNA binding protein.

PubMed

Whittier, R F; Chase, J W

1983-01-01

Mutations affecting single-strand DNA binding protein (SSB) impair induction of mutagenic (SOS) repair. To further investigate the role of SSB in SOS induction and DNA repair, isogenic strains were constructed combining the ssb+, ssb-1 or ssb-113 alleles with one or more mutations known to alter regulation of damage inducible functions. As is true in ssb+ strains tif-1 (recA441) was found to allow thermal induction of prophage lambda + and Weigle reactivation in ssb-1 and ssb-113 strains. Furthermore, tif-1 decreased the UV sensitivity of the ssb-113 strain slightly and permitted UV induction of prophage lambda + at 30 degrees C. Strains carrying the recAo281 allele were also constructed. This mutation causes high constitutive levels of RecA protein synthesis and relieves much of the UV sensitivity conferred by lexA- alleles without restoring SOS (error-prone) repair. In contrast, the recAo281 allele failed to alleviate the UV sensitivity associated with either ssb- mutation. In a lexA1 recAo281 background the ssb-1 mutation increased the extent of postirradiation DNA degradation and concommitantly increased UV sensitivity 20-fold to the level exhibited by a recA1 strain. The ssb-113 mutation also increased UV sensitivity markedly in this background but did so without greatly increasing postirradiation DNA degradation. These results suggest a direct role for SSB in recombinational repair apart from and in addition to its role in facilitating induction of the recA-lexA regulon.

Cholesteric liquid crystals as sensor materials for bioequivalent UV-dosimetry

NASA Astrophysics Data System (ADS)

Lisetski, Longin N.; Vashchenko, O. V.; Panikarskaya, V. D.; Sidletskiy, O. T.; Terenetskaya, Irina P.

2003-12-01

Selective reflection spectra have been studied for cholesteric matrices doped with certain steroids of vitamin D group, and substantial effect of the dopants upon the helical pitch was noted. Under UV irradiation, shifts of selective reflection peaks were observed. It is argued that the effect studied can be used for monitoring of vitamin D formation reactions induced by UV irradiation, thus being a base of bioequivalent UV dosimetry.

Assessment of UV biological spectral weighting functions for phenolic metabolites and growth responses in silver birch seedlings.

PubMed

Kotilainen, Titta; Venäläinen, Tuulia; Tegelberg, Riitta; Lindfors, Anders; Julkunen-Tiitto, Riitta; Sutinen, Sirkka; O'Hara, Robert B; Aphalo, Pedro J

2009-01-01

In research concerning stratospheric ozone depletion, action spectra are used as biological spectral weighting functions (BSWFs) for describing the effects of UV radiation on plant responses. Our aim was to evaluate the appropriateness of six frequently used BSWFs that differ in effectiveness with increasing wavelength. The evaluation of action spectra was based on calculating the effective UV radiation doses according to 1-2) two formulations of the generalized plant action spectrum, 3) a spectrum for ultraviolet induced erythema in human skin, 4) a spectrum for the accumulation of a flavonol in Mesembryanthemum crystallinum, 5) a spectrum for DNA damage in alfalfa seedlings and 6) the plant growth action spectrum. We monitored effects of UV radiation on the concentration of individual UV absorbing metabolites and chlorophyll concentrations in leaves and growth responses of silver birch (Betula pendula) seedlings. Experiments were conducted outdoors using plastic films attenuating different parts of the UV spectrum. Chlorophyll concentrations and growth were not affected by the UV treatments. The response to UV radiation varied between and within groups of phenolics. In general, the observed responses of phenolic groups and individual flavonoids were best predicted by action spectra extending into the UV-A region with moderate effectiveness.

Penetration of UV Radiation in the Earth's Oceans

NASA Technical Reports Server (NTRS)

Mitchell, B. Greg; Lubin, Dan

2005-01-01

This project was a collaboration between SIO/UCSD and NASA/GSFC to develop a global estimation of the penetration of UV light into open ocean waters, and into coastal waters. We determined the ocean UV reflectance spectra seen by satellites above the atmosphere by combining existing sophisticated radiative transfer models with in situ UV Visible data sets to improve coupled radiance estimates both underwater and within the atmosphere. Results included improved estimates of surface spectral irradiance, 0.3-1.0 micron, and estimates of photosynthetic inhibition, DNA mutation, and CO production. Data sets developed under this proposal have been made publicly available via submission to the SeaWiFS Bio-Optical Archive and Storage System. Numerous peer-reviewed publications and conference proceedings and abstracts resulted from the work supported by this research award.

Characterization of an Escherichia coli mutant (radB101) sensitive to. gamma. and uv radiation, and methyl methanesulfonate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sargentini, N.J.; Smith, K.C.

1983-03-01

After N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis of Escherichia coli K-12 (xthA14), an X-ray-sensitive mutant was isolated. This sensitivity is due to a mutation, radB101, which is located at 56.5 min on the E.coli K-12 linkage map. The radB101 mutation sensitized wild-type cells to ..gamma.. and uv radiation, and to methyl methanesulfonate. When known DNA repair-deficient mutants were ranked for their ..gamma..-radiation sensitivity relative to their uv-radiation sensitivity, their order was (starting with the most selectively ..gamma..-radiation-sensitive strain): recB21, radB101, wild type, polA1, recF143, lexA101, recA56, uvrD3, and uvrA6. The radB mutant was normal for ..gamma..- and uv-radiation mutagenesis, it showed only a slightmore » enhancement of ..gamma..- and uv-radiation-induced DNA degradation, and it was approx. 60% deficient in recombination ability. The radB gene is suggested to play a role in the recA gene-dependent (Type III) repair of DNA single-strand breaks after ..gamma.. irradiation and in postreplication repair after uv irradiation for the following reasons: the radB strain was normal for the host-cell reactivation of ..gamma..- and uv-irradiated bacteriophage lambda; the radB mutation did not sensitize a recA strain, but did sensitize a polA strain to ..gamma.. and uv radiation; the radB mutation sensitized a uvrB strain to uv radiation.« less

A compromised yeast RNA polymerase II enhances UV sensitivity in the absence of global genome nucleotide excision repair.

PubMed

Wong, J M; Ingles, C J

2001-02-01

Nucleotide excision repair is the major pathway responsible for removing UV-induced DNA damage, and is therefore essential for cell survival following exposure to UV radiation. In this report, we have assessed the contributions of some components of the RNA polymerase II (Pol II) transcription machinery to UV resistance in Saccharomyces cerevisiae. Deletion of the gene encoding the Pol II elongation factor TFIIS (SII) resulted in enhanced UV sensitivity, but only in the absence of global genome repair dependent on the RAD7 and RAD16 genes, a result seen previously with deletions of RAD26 and RAD28, yeast homologs of the human Cockayne syndrome genes CSB and CSA, respectively. A RAD7/16-dependent reduction in survival after UV irradiation was also seen in the presence of mutations in RNA Pol II that confer a defect in its response to SII, as well as with other mutations which reside in regions of the largest subunit of Pol II not involved in SII interactions. Indeed, an increase in UV sensitivity was achieved by simply decreasing the steadystate level of RNA Pol II. Truncation of the C-terminal domain and other RNA Pol II mutations conferred sensitivity to the ribonucleotide reductase inhibitor hydroxyurea and induction of RNR1 and RNR2 mRNAs after UV irradiation was attenuated in these mutant cells. That UV sensitivity can be a consequence of mutations in the RNA Pol II machinery in yeast cells suggests that alterations in transcriptional programs could underlie some of the pathophysiological defects seen in the human disease Cockayne syndrome.

P16 UV mutations in human skin epithelial tumors.

PubMed

Soufir, N; Molès, J P; Vilmer, C; Moch, C; Verola, O; Rivet, J; Tesniere, A; Dubertret, L; Basset-Seguin, N

1999-09-23

The p16 gene expresses two alternative transcripts (p16alpha and p16beta) involved in tumor suppression via the retinoblastoma (Rb) or p53 pathways. Disruption of these pathways can occur through inactivation of p16 or p53, or activating mutations of cyclin dependant kinase 4 gene (Cdk4). We searched for p16, Cdk4 and p53 gene mutations in 20 squamous cell carcinomas (SSCs), 1 actinic keratosis (AK), and 28 basal cell carcinomas (BCCs), using PCR-SSCP. A deletion and methylation analysis of p16 was also performed. Six different mutations (12%) were detected in exon 2 of p16 (common to p16alpha and p16beta), in five out of 21 squamous lesions (24%) (one AK and four SCCs) and one out of 28 BCCs (3.5%). These included four (66%) ultraviolet (UV)-type mutations (two tandems CC : GG to TT : AA transitions and two C : G to T : A transitions at dipyrimidic site) and two transversions. P53 mutations were present in 18 samples (37%), mostly of UV type. Of these, only two (one BCC and one AK) harboured simultaneously mutations of p16, but with no consequence on p16beta transcript. Our data demonstrate for the first time the presence of p16 UV induced mutations in non melanoma skin cancer, particularly in the most aggressive SCC type, and support that p16 and p53 are involved in two independent pathways in skin carcinogenesis.

Photochemical isomerizations of thiosemicarbazide, a matrix isolation study.

PubMed

Rostkowska, Hanna; Lapinski, Leszek; Kozankiewicz, Boleslaw; Nowak, Maciej J

2012-10-11

Two thione conformers of monomeric thiosemicarbazide were trapped from the gas phase into a low-temperature Ar matrix. A phototransformation converting the less stable form of the compound into the most stable conformer was induced by irradiation with near-IR (λ = 1462 nm) or UV (λ > 320 nm) light. This photoeffect allowed separation of the IR spectra of the observed thione forms. The structures of both observed isomers were identified by comparison of the separated experimental IR spectra with the spectra theoretically predicted for two most stable forms of the compound. The population ratio of the two conformers in an Ar matrix, prior to any irradiation, was estimated to be equal ≈2:1. Irradiation of matrix-isolated thiosemicarbazide with shorter-wavelength UV (λ > 270 nm) light induced a phototautomeric reaction generating thiol forms of the compound.

UV laser-induced fluorescence spectroscopy and laser Doppler flowmetry in the diagnostics of alopecia

NASA Astrophysics Data System (ADS)

Skomorokha, Diana P.; Pigoreva, Yulia N.; Salmin, Vladimir V.

2016-04-01

Development of optical biopsy methods has a great interest for medical diagnostics. In clinical and experimental studies it is very important to analyze blood circulation quickly and accurately, thereby laser Doppler flowmetry (LDF) is widely used. UV laser-induced fluorescence spectroscopy (UV LIFS) is express highly sensitive and widely-spread method with no destructive impact, high excitation selectivity and the possibility to use in highly scattering media. The goal of this work was to assess a correlation of UV laser-induced fluorescence spectroscopy and laser Doppler flowmetry parameters, and a possibility to identify or to differentiate various types of pathological changes in tissues according to their autofluorescence spectra. Three groups of patients with diffuse (symptomatic) alopecia, androgenic alopecia, and focal alopecia have been tested. Each groups consisted of not less than 20 persons. The measurements have been done in the parietal and occipital regions of the sculls. We used the original automated spectrofluorimeter to record autofluorescence spectra, and standard laser Doppler flowmeter BLF-21 (Transonic Systems, Inc., USA) to analyze the basal levels of blood circulation. Our results show that UV LIFS accurately distinguishes the zones with different types of alopecia. We found high correlation of the basal levels of blood circulation and the integrated intensity of autofluorescence in the affected tissue.

Comparative study of the mutagenetic effect of uv radiation and diethyl sulfate vapors on strain 1321 of Actinomyces antocyaneus (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alieva, R.M.; Shigaeva, M.Kh.

1970-01-01

A comparative study was made of the effects of uv irradiation and diethyl sulfate vapors on the frequency of the origin of different types of mutation in strain 1321 of A. antocyaneus. Of the two mutagens used, diethyl sulfate vapors appeared very effective in the proportion of new types of morphological mutations. Treatment with it caused greater variability with respect to indications of antibiotic formation with a larger yield of the' plus'' variant than with uv irradiation. Twelve biochemical mutants induced by uv irradiation and nine biochemical mutants under the effects of diethyl sulfate vapor were selected. -The majority ofmore » the biochemical mutants proved to be instable and reverted to the original prototrophic state. (tr-auth)« less

MHY1485 ameliorates UV-induced skin cell damages via activating mTOR-Nrf2 signaling

PubMed Central

Yang, Bo; Xu, Qiu-Yun; Guo, Chun-Yan; Huang, Jin-Wen; Wang, Shu-Mei; Li, Yong-Mei; Tu, Ying; He, Li; Bi, Zhi-Gang; Ji, Chao; Cheng, Bo

2017-01-01

Ultra Violet (UV)-caused skin cell damage is a main cause of skin cancer. Here, we studied the activity of MHY1485, a mTOR activator, in UV-treated skin cells. In primary human skin keratinocytes, HaCaT keratinocytes and human skin fibroblasts, MHY1485 ameliorated UV-induced cell death and apoptosis. mTOR activation is required for MHY1485-induced above cytoprotective actions. mTOR kinase inhibitors (OSI-027, AZD-8055 and AZD-2014) or mTOR shRNA knockdown almost abolished MHY1485-induced cytoprotection. Further, MHY1485 treatment in skin cells activated mTOR downstream NF-E2-related factor 2 (Nrf2) signaling, causing Nrf2 Ser-40 phosphorylation, stabilization/upregulation and nuclear translocation, as well as mRNA expression of Nrf2-dictated genes. Contrarily, Nrf2 knockdown or S40T mutation almost nullified MHY1485-induced cytoprotection. MHY1485 suppressed UV-induced reactive oxygen species production and DNA single strand breaks in skin keratinocytes and fibroblasts. Together, we conclude that MHY1485 inhibits UV-induced skin cell damages via activating mTOR-Nrf2 signaling. PMID:28061443

UV Raman spectroscopy of H2-air flames excited with a narrowband KrF laser

NASA Technical Reports Server (NTRS)

Shirley, John A.

1990-01-01

Raman spectra of H2 and H2O in flames excited by a narrowband KrF excimer laser are reported. Observations are made over a porous-plug, flat-flame burner reacting H2 in air, fuel-rich with nitrogen dilution to control the temperature, and with an H2 diffusion flame. Measurements made from UV Raman spectra show good agreement with measurements made by other means, both for gas temperature and relative major species concentrations. Laser-induced fluorescence interferences arising from OH and O2 are observed in emission near the Raman spectra. These interferences do not preclude Raman measurements, however.

The yeast p53 functional assay: a new tool for molecular epidemiology. Hopes and facts.

PubMed

Fronza, G; Inga, A; Monti, P; Scott, G; Campomenosi, P; Menichini, P; Ottaggio, L; Viaggi, S; Burns, P A; Gold, B; Abbondandolo, A

2000-04-01

The assumption of molecular epidemiology that carcinogens leave fingerprints has suggested that analysis of the frequency, type, and site of mutations in genes frequently altered in carcinogenesis may provide clues to the identification of the factors contributing to carcinogenesis. In this mini-review, we revise the development, and validation of the yeast-based p53 functional assay as a new tool for molecular epidemiology. We show that this assay has some very interesting virtues but also has some drawbacks. The yeast functional assay can be used to determine highly specific mutation fingerprints in the human p53 cDNA sequence. Discrimination is possible when comparing mutation spectra induced by sufficiently different mutagens. However, we also reported that the same carcinogen may induce distinguishable mutation spectra due to known influencing factors.

Photodamage: all signs lead to actinic keratosis and early squamous cell carcinoma.

PubMed

Wei, Jerry; Kok, Lai Fong; Byrne, Scott N; Halliday, Gary M

2015-01-01

Ultraviolet (UV) radiation is likely to drive the initiation and progression of skin cancer from actinic keratosis to squamous cell carcinoma. Signs of photodamage occur at multiple steps. UV radiation damages many cellular constituents, including lipids, proteins and DNA, all of which are likely to contribute to UV-induced skin cancer. Two biological events culminating from photodamage are mutations in the genes critical to the control of cell division, differentiation and invasion and immunosuppression. DNA photodamage, if unrepaired prior to cell division, can result in the incorporation of an incorrect nucleotide into newly synthesised DNA. Mutations in critical genes contribute to carcinogenesis. Photodamage to proteins such as those involved in DNA repair or proteins or lipids involved in cellular signalling can interfere with this repair process and contribute to mutagenesis. Mutations in key genes, including TP53, BRM, PTCH1, and HRAS, contribute to skin carcinogenesis. UV also damages immunity. Photodamage to DNA and signalling lipids as well as other molecular changes are detrimental to the key cells that regulate immunity. Photodamaged dendritic cells and altered responses by mast cells lead to the activation of T and B regulatory cells that suppress immunity to the protein products of UV-mutated genes. This stops the immune response from its protective function of destroying mutated cells, enabling the transformed cells to progress to skin cancer. UV appears to play a pivotal role at each of these steps, and therefore, signs of photodamage point to the development of skin cancer. © 2015 S. Karger AG, Basel.

Induction of diphtheria toxin-resistant mutants in human cells by ultraviolet light

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rocchi, P.; Ferreri, A.M.; Capucci, A.

1981-01-01

Stable spontaneous mutants resistant to the protein synthesis inhibitor diphtheria toxin (DT) have been selected in human cell line EUE at a very low frequency (less than 8 x 10(-6)). U.v.-induced mutation has been quantitatively measured: treatment of cells with u.v. light increased the frequencies of diphtheria toxin resistant (DTr) mutants up to 1000-fold. The maximum recovery of DTr mutants was observed after a short expression period, for all u.v. doses tested, and was followed by a decrease in mutation frequency on subsequent passages.

Induction of diphtheria toxin-resistant mutants in human cells by ultraviolet light

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rocchi, P.; Ferreri, A.M.; Capucci, A.

1981-01-01

Stable spontaneous mutants resistant to the protein synthesis inhibitor diphtheria toxin (DT) have been selected in human cell line EUE at a very low frequency (< 8 x 10/sup -6/). U.v.-induced mutation has been quantitatively measured: treatment of cells with u.v. light increased the frequencies of diphtheria toxin resistant (DTsup(r)) mutants up to 1000-fold. The maximum recovery of DTsup(r) mutants was observed after a short expression period, for all u.v. doses tested, and was followed by a decrease in mutation frequency on subsequent passages.

The Role of Inducible DNA Repair in W-Reactivation and Related Phenomena.

DTIC Science & Technology

1981-10-14

unexcised dimers in X DNA. This was consistent with the finding of Tomilin and Mosevitskaya (1975) which showed that the UV-endonuclease from Micrococcus ...of DNA in vitro with UV-endonuclease from Micrococcus luteus. Mutat. Res. 27, 147-156 (1975) Tomizawa, J., Ogawa, T.: Effect of ultraviolet irradiation

Determinants of spontaneous mutation in the bacterium Escherichia coli as revealed by whole-genome sequencing

PubMed Central

Foster, Patricia L.; Lee, Heewook; Popodi, Ellen; Townes, Jesse P.; Tang, Haixu

2015-01-01

A complete understanding of evolutionary processes requires that factors determining spontaneous mutation rates and spectra be identified and characterized. Using mutation accumulation followed by whole-genome sequencing, we found that the mutation rates of three widely diverged commensal Escherichia coli strains differ only by about 50%, suggesting that a rate of 1–2 × 10−3 mutations per generation per genome is common for this bacterium. Four major forces are postulated to contribute to spontaneous mutations: intrinsic DNA polymerase errors, endogenously induced DNA damage, DNA damage caused by exogenous agents, and the activities of error-prone polymerases. To determine the relative importance of these factors, we studied 11 strains, each defective for a major DNA repair pathway. The striking result was that only loss of the ability to prevent or repair oxidative DNA damage significantly impacted mutation rates or spectra. These results suggest that, with the exception of oxidative damage, endogenously induced DNA damage does not perturb the overall accuracy of DNA replication in normally growing cells and that repair pathways may exist primarily to defend against exogenously induced DNA damage. The thousands of mutations caused by oxidative damage recovered across the entire genome revealed strong local-sequence biases of these mutations. Specifically, we found that the identity of the 3′ base can affect the mutability of a purine by oxidative damage by as much as eightfold. PMID:26460006

The Saccharomyces cerevisiae RAD9, RAD17, RAD24 and MEC3 genes are required for tolerating irreparable, ultraviolet-induced DNA damage.

PubMed Central

Paulovich, A G; Armour, C D; Hartwell, L H

1998-01-01

In wild-type Saccharomyces cerevisiae, a checkpoint slows the rate of progression of an ongoing S phase in response to exposure to a DNA-alkylating agent. Mutations that eliminate S phase regulation also confer sensitivity to alkylating agents, leading us to suggest that, by regulating the S phase rate, cells are either better able to repair or better able to replicate damaged DNA. In this study, we determine the effects of mutations that impair S phase regulation on the ability of excision repair-defective cells to replicate irreparably UV-damaged DNA. We assay survival after UV irradiation, as well as the genetic consequences of replicating a damaged template, namely mutation and sister chromatid exchange induction. We find that RAD9, RAD17, RAD24, and MEC3 are required for UV-induced (although not spontaneous) mutagenesis, and that RAD9 and RAD17 (but not REV3, RAD24, and MEC3) are required for maximal induction of replication-dependent sister chromatid exchange. Therefore, checkpoint genes not only control cell cycle progression in response to damage, but also play a role in accommodating DNA damage during replication. PMID:9725831

The Saccharomyces cerevisiae RAD9, RAD17, RAD24 and MEC3 genes are required for tolerating irreparable, ultraviolet-induced DNA damage.

PubMed

Paulovich, A G; Armour, C D; Hartwell, L H

1998-09-01

In wild-type Saccharomyces cerevisiae, a checkpoint slows the rate of progression of an ongoing S phase in response to exposure to a DNA-alkylating agent. Mutations that eliminate S phase regulation also confer sensitivity to alkylating agents, leading us to suggest that, by regulating the S phase rate, cells are either better able to repair or better able to replicate damaged DNA. In this study, we determine the effects of mutations that impair S phase regulation on the ability of excision repair-defective cells to replicate irreparably UV-damaged DNA. We assay survival after UV irradiation, as well as the genetic consequences of replicating a damaged template, namely mutation and sister chromatid exchange induction. We find that RAD9, RAD17, RAD24, and MEC3 are required for UV-induced (although not spontaneous) mutagenesis, and that RAD9 and RAD17 (but not REV3, RAD24, and MEC3) are required for maximal induction of replication-dependent sister chromatid exchange. Therefore, checkpoint genes not only control cell cycle progression in response to damage, but also play a role in accommodating DNA damage during replication.

Differential responses to high- and low-dose ultraviolet-B stress in tobacco Bright Yellow-2 cells

PubMed Central

Takahashi, Shinya; Kojo, Kei H.; Kutsuna, Natsumaro; Endo, Masaki; Toki, Seiichi; Isoda, Hiroko; Hasezawa, Seiichiro

2015-01-01

Ultraviolet (UV)-B irradiation leads to DNA damage, cell cycle arrest, growth inhibition, and cell death. To evaluate the UV-B stress–induced changes in plant cells, we developed a model system based on tobacco Bright Yellow-2 (BY-2) cells. Both low-dose UV-B (low UV-B: 740 J m−2) and high-dose UV-B (high UV-B: 2960 J m−2) inhibited cell proliferation and induced cell death; these effects were more pronounced at high UV-B. Flow cytometry showed cell cycle arrest within 1 day after UV-B irradiation; neither low- nor high-UV-B–irradiated cells entered mitosis within 12 h. Cell cycle progression was gradually restored in low-UV-B–irradiated cells but not in high-UV-B–irradiated cells. UV-A irradiation, which activates cyclobutane pyrimidine dimer (CPD) photolyase, reduced inhibition of cell proliferation by low but not high UV-B and suppressed high-UV-B–induced cell death. UV-B induced CPD formation in a dose-dependent manner. The amounts of CPDs decreased gradually within 3 days in low-UV-B–irradiated cells, but remained elevated after 3 days in high-UV-B–irradiated cells. Low UV-B slightly increased the number of DNA single-strand breaks detected by the comet assay at 1 day after irradiation, and then decreased at 2 and 3 days after irradiation. High UV-B increased DNA fragmentation detected by the terminal deoxynucleotidyl transferase dUTP nick end labeling assay 1 and 3 days after irradiation. Caffeine, an inhibitor of ataxia telangiectasia mutated (ATM) and ataxia telangiectasia and Rad3-related (ATR) checkpoint kinases, reduced the rate of cell death in high-UV-B–irradiated cells. Our data suggest that low-UV-B–induced CPDs and/or DNA strand-breaks inhibit DNA replication and proliferation of BY-2 cells, whereas larger contents of high-UV-B–induced CPDs and/or DNA strand-breaks lead to cell death. PMID:25954287

Regulation of miR-21 expression in human melanoma via UV-ray-induced melanin pigmentation.

PubMed

Lin, Kuan-Yu; Chen, Chien-Min; Lu, Cheng-You; Cheng, Chun-Yuan; Wu, Yu-Hsin

2017-08-01

Excessive environmental ultraviolet (UV) radiation produces genetic mutations that can lead to skin cancer. This study was designed to assess the potential inhibitory activity of microRNA-21 (miR-21) on the UV irradiation-stimulated melanogenesis signal pathway in melanoma cells. The molecular mechanism of miR-21-induced inhibitory activity on UV-ray-stimulated melanogenesis-regulating proteins was examined in A375.S2 human melanoma and B16F10 mouse melanoma cells. UV irradiation for 30 min induced melanogenesis signal pathway by increasing melanin production and the number of A375.S2 cells. Similarly, UV radiation increased the expression of α-melanocyte-stimulating hormone (α-MSH) protein and decreased the melanogenesis-regulating signal, such as EGFR and Akt phosphorylation. Notably, miR-21 overexpression in UV-ray-stimulated A375.S2 cells decreased α-MSH expression and increased EGFR and Akt phosphorylation levels. Furthermore, miR-21 on UV-ray- induced melanogenesis was down-regulated by the Akt inhibitor and the EGFR inhibitor (Gefitinib). Results suggest that the suppressive activity of miR-21 on UV-ray-stimulated melanogenesis may involve the down-regulation of α-MSH and the activation in both of EGFR and Akt. © 2017 Wiley Periodicals, Inc.

Involvement of activation-induced cytidine deaminase in skin cancer development.

PubMed

Nonaka, Taichiro; Toda, Yoshinobu; Hiai, Hiroshi; Uemura, Munehiro; Nakamura, Motonobu; Yamamoto, Norio; Asato, Ryo; Hattori, Yukari; Bessho, Kazuhisa; Minato, Nagahiro; Kinoshita, Kazuo

2016-04-01

Most skin cancers develop as the result of UV light-induced DNA damage; however, a substantial number of cases appear to occur independently of UV damage. A causal link between UV-independent skin cancers and chronic inflammation has been suspected, although the precise mechanism underlying this association is unclear. Here, we have proposed that activation-induced cytidine deaminase (AID, encoded by AICDA) links chronic inflammation and skin cancer. We demonstrated that Tg mice expressing AID in the skin spontaneously developed skin squamous cell carcinoma with Hras and Trp53 mutations. Furthermore, genetic deletion of Aicda reduced tumor incidence in a murine model of chemical-induced skin carcinogenesis. AID was expressed in human primary keratinocytes in an inflammatory stimulus-dependent manner and was detectable in human skin cancers. Together, the results of this study indicate that inflammation-induced AID expression promotes skin cancer development independently of UV damage and suggest AID as a potential target for skin cancer therapeutics.

Involvement of activation-induced cytidine deaminase in skin cancer development

PubMed Central

Toda, Yoshinobu; Hiai, Hiroshi; Uemura, Munehiro; Nakamura, Motonobu; Hattori, Yukari; Bessho, Kazuhisa; Minato, Nagahiro

2016-01-01

Most skin cancers develop as the result of UV light–induced DNA damage; however, a substantial number of cases appear to occur independently of UV damage. A causal link between UV-independent skin cancers and chronic inflammation has been suspected, although the precise mechanism underlying this association is unclear. Here, we have proposed that activation-induced cytidine deaminase (AID, encoded by AICDA) links chronic inflammation and skin cancer. We demonstrated that Tg mice expressing AID in the skin spontaneously developed skin squamous cell carcinoma with Hras and Trp53 mutations. Furthermore, genetic deletion of Aicda reduced tumor incidence in a murine model of chemical-induced skin carcinogenesis. AID was expressed in human primary keratinocytes in an inflammatory stimulus–dependent manner and was detectable in human skin cancers. Together, the results of this study indicate that inflammation-induced AID expression promotes skin cancer development independently of UV damage and suggest AID as a potential target for skin cancer therapeutics. PMID:26974156

TRAIP promotes DNA damage response during genome replication and is mutated in primordial dwarfism.

PubMed

Harley, Margaret E; Murina, Olga; Leitch, Andrea; Higgs, Martin R; Bicknell, Louise S; Yigit, Gökhan; Blackford, Andrew N; Zlatanou, Anastasia; Mackenzie, Karen J; Reddy, Kaalak; Halachev, Mihail; McGlasson, Sarah; Reijns, Martin A M; Fluteau, Adeline; Martin, Carol-Anne; Sabbioneda, Simone; Elcioglu, Nursel H; Altmüller, Janine; Thiele, Holger; Greenhalgh, Lynn; Chessa, Luciana; Maghnie, Mohamad; Salim, Mahmoud; Bober, Michael B; Nürnberg, Peter; Jackson, Stephen P; Hurles, Matthew E; Wollnik, Bernd; Stewart, Grant S; Jackson, Andrew P

2016-01-01

DNA lesions encountered by replicative polymerases threaten genome stability and cell cycle progression. Here we report the identification of mutations in TRAIP, encoding an E3 RING ubiquitin ligase, in patients with microcephalic primordial dwarfism. We establish that TRAIP relocalizes to sites of DNA damage, where it is required for optimal phosphorylation of H2AX and RPA2 during S-phase in response to ultraviolet (UV) irradiation, as well as fork progression through UV-induced DNA lesions. TRAIP is necessary for efficient cell cycle progression and mutations in TRAIP therefore limit cellular proliferation, providing a potential mechanism for microcephaly and dwarfism phenotypes. Human genetics thus identifies TRAIP as a component of the DNA damage response to replication-blocking DNA lesions.

Inactivation and mutation induction in Saccharomyces cerevisiae exposed to simulated sunlight: evaluation of action spectra.

PubMed

Schenk-Meuser, K; Pawlowsky, K; Kiefer, J

1992-07-15

The effectiveness of polychromatic light irradiation was investigated for haploid yeast cells. Inactivation and mutation induction were measured in both a RAD-wildtype strain and an excision-repair defective strain. The behaviour of vegetative "wet" cells was compared to that of dehydrated cells. The aim of the study was to assess the interaction of UVC with other wavelengths in cells of different states of humidity. The irradiation procedure was therefore carried out using a solar simulator either with full spectrum or with a UVC-blocking filter (modified sunlight) added. The results were analysed on the basis of separately determined action spectra. The summation of the efficiency of individual wavelengths was compared to the values obtained from polychromatic irradiation. It is shown that the effects caused by the whole-spectrum irradiation in wet cells can be predicted sufficiently from the calculation, while dried wildtype cells exhibit higher mutation rates. Thus it can be assumed that drying-specific damage leads to lethal and mutagenic lesions which are processed in different ways, causing a synergistic behaviour in mutation induction. Irradiation of vegetative cells with modified sunlight (UVC-) results in less inactivation and lower mutation rates than were calculated. From these results it can be concluded that this antagonistic behaviour is caused by the interaction of near-UV photoproducts.

[Light protection for xeroderma pigmentosum].

PubMed

Ettinger, M; Berneburg, M

2017-05-01

Xeroderma pigmentosum is a rare autosomal recessive disorder which is caused by germinal mutations responsible for the repair of ultraviolet (UV) radiation-induced DNA lesions. It is characterized by hypersensitivity to UV radiation, poikiloderma, ocular surface disease, and in some patients pronounced sunburn and neurological disease. Patients have a very high risk of developing ocular and skin cancer on exposed body sites. No cure is available for these patients except complete protection from all types of UV radiation.

WRNIP1 functions upstream of DNA polymerase η in the UV-induced DNA damage response

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoshimura, Akari, E-mail: akari_yo@stu.musashino-u.ac.jp; Kobayashi, Yume; Tada, Shusuke

2014-09-12

Highlights: • The UV sensitivity of POLH{sup −/−} cells was suppressed by disruption of WRNIP1. • In WRNIP1{sup −/−/−}/POLH{sup −/−} cells, mutation frequencies and SCE after irradiation reduced. • WRNIP1 defect recovered rate of fork progression after irradiation in POLH{sup −/−} cells. • WRNIP1 functions upstream of Polη in the translesion DNA synthesis pathway. - Abstract: WRNIP1 (WRN-interacting protein 1) was first identified as a factor that interacts with WRN, the protein that is defective in Werner syndrome (WS). WRNIP1 associates with DNA polymerase η (Polη), but the biological significance of this interaction remains unknown. In this study, we analyzedmore » the functional interaction between WRNIP1 and Polη by generating knockouts of both genes in DT40 chicken cells. Disruption of WRNIP1 in Polη-disrupted (POLH{sup −/−}) cells suppressed the phenotypes associated with the loss of Polη: sensitivity to ultraviolet light (UV), delayed repair of cyclobutane pyrimidine dimers (CPD), elevated frequency of mutation, elevated levels of UV-induced sister chromatid exchange (SCE), and reduced rate of fork progression after UV irradiation. These results suggest that WRNIP1 functions upstream of Polη in the response to UV irradiation.« less

TERT promoter mutation status as an independent prognostic factor in cutaneous melanoma.

PubMed

Griewank, Klaus G; Murali, Rajmohan; Puig-Butille, Joan Anton; Schilling, Bastian; Livingstone, Elisabeth; Potrony, Miriam; Carrera, Cristina; Schimming, Tobias; Möller, Inga; Schwamborn, Marion; Sucker, Antje; Hillen, Uwe; Badenas, Celia; Malvehy, Josep; Zimmer, Lisa; Scherag, André; Puig, Susana; Schadendorf, Dirk

2014-09-01

Recently, TERT promoter mutations were identified at high frequencies in cutaneous melanoma tumor samples and cell lines. The mutations were found to have a UV-signature and to lead to increased TERT gene expression. We analyzed a large cohort of melanoma patients for the presence and distribution of TERT promoter mutations and their association with clinico-pathological characteristics. 410 melanoma tumor samples were analyzed by Sanger sequencing for the presence of TERT promoter mutations. An analysis of associations between mutation status and various clinical and pathologic variables was performed. TERT promoter mutations were identified in 154 (43%) of 362 successfully sequenced melanomas. Mutation frequencies varied between melanoma subtype, being most frequent in melanomas arising in nonacral skin (48%) and melanomas with occult primary (50%), and less frequent in mucosal (23%), and acral (19%) melanomas. Mutations carried a UV signature (C>T or CC>TT). The presence of TERT promoter mutations was associated with factors such as BRAF or NRAS mutation (P < .001), histologic type (P = .002), and Breslow thickness (P < .001). TERT promoter mutation was independently associated with poorer overall survival in patients with nonacral cutaneous melanomas (median survival 80 months vs 291 months for wild-type; hazard ratio corrected for other covariates 2.47; 95% confidence interval [CI] = 1.29 to 4.74; P = .006). UV-induced TERT promoter mutations are one of the most frequent genetic alterations in melanoma, with frequencies varying depending on melanoma subtype. In nonacral cutaneous melanomas, presence of TERT promoter mutations is independently associated with poor prognosis. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Variation of p53 mutational spectra between carcinoma of the upper and lower respiratory tract.

PubMed

Law, J C; Whiteside, T L; Gollin, S M; Weissfeld, J; El-Ashmawy, L; Srivastava, S; Landreneau, R J; Johnson, J T; Ferrell, R E

1995-07-01

Mutations of the p53 tumor suppressor gene are the most common genetic alterations associated with human cancer. Tumor-associated p53 mutations often show characteristic tissue-specific profiles which may infer environmentally induced mutational mechanisms. The p53 mutational frequency and spectrum were determined for 95 carcinomas of the upper and lower respiratory tract (32 lung and 63 upper respiratory tract). Mutations were identified at a frequency of 30% in upper respiratory tract (URT) tumors and 31% in lung tumors. All 29 identified mutations were single-base substitutions. Comparison of the frequency of specific base substitutions between lung and URT showed a striking difference. Transitions occurred at a frequency of 68% in URT, but only 30% in lung. Mutations involving G:C-->A:T transitions, which are commonly reported in gastric and esophageal tumors, were the most frequently identified alteration in URT (11/19). Mutations involving G:C-->T:A transversions, which were relatively common in lung tumors (3/10) and are representative of tobacco smoke-induced mutations were rare in URT tumors (1/19). Interestingly, G:C-->A:T mutations at CpG sites, which are characteristic of endogenous processes, were observed frequently in URT tumors (9/19) but only rarely in lung tumors (1/10), suggesting that both endogenous and exogenous factors are responsible for the observed differences in mutational spectra between the upper and lower respiratory systems.

A phase II randomized placebo-controlled trial of oral N-acetylcysteine for protection of melanocytic nevi against UV-induced oxidative stress in vivo

PubMed Central

Cassidy, Pamela B.; Liu, Tong; Florell, Scott R.; Honeggar, Matthew; Leachman, Sancy A.; Boucher, Kenneth M.; Grossman, Douglas

2016-01-01

Oxidative stress plays a role in UV-induced melanoma, which may arise from melanocytic nevi. We investigated whether oral administration of the antioxidant N-acetylcysteine (NAC) could protect nevi from oxidative stress in vivo in the setting of acute UV exposure. The minimal erythemal dose (MED) was determined for 100 patients at increased risk for melanoma. Patients were randomized to receive a single dose (1200 mg) of NAC or placebo, in double-blind fashion, and then one nevus was irradiated (1–2 MED) using a solar simulator. One day later, the MED was re-determined and the irradiated nevus and a control un-irradiated nevus were removed for histologic analysis and examination of biomarkers of NAC metabolism and UV-induced oxidative stress. Increased expression of 8-oxoguanine, thioredoxin reductase-1, and γ-glutamylcysteine synthase modifier subunit were consistently seen in UV-treated compared to unirradiated nevi. However, no significant differences were observed in these UV-induced changes or in the pre- and post-intervention MED between those patients receiving NAC vs. placebo. Similarly, no significant differences were observed in UV-induced changes between subjects with germline wild-type vs. loss of function mutations in the melanocortin-1 receptor. Nevi showed similar changes of UV-induced oxidative stress in an open-label post-trial study in 10 patients who received NAC 3 h before nevus irradiation. Thus a single oral dose of NAC did not effectively protect nevi from UV-induced oxidative stress under the conditions examined. PMID:27920018

Xeroderma pigmentosum variant cells are less likely than normal cells to incorporate dAMP opposite photoproducts during replication of UV-irradiated plasmids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Y.C.; Maher, V.M.; McCormich, J.J.

1991-09-01

Xeroderma pigmentosum (XP) variant patients show the clinical characteristics of the disease, with increased frequencies of skin cancer, but their cells have a normal, or nearly normal, rate of nucleotide excision repair of UV-induced DNA damage and are only slightly more sensitive than normal cells to the cytotoxic effect of UV radiation. However, they are significantly more sensitive to its mutagenic effect. To examine the mechanisms responsible for this hypermutability, the authors transfected an XP variant cell line with a UV-irradiated (at 254 nm) shuttle vector carrying the {sup F} gene as a target for mutations, allowed replication of themore » plasmid, determined the frequency and spectrum of mutations induced, and compared the results with those obtained previously when irradiated plasmids carrying the same target gene replicated in a normal cell line. The frequency of mutants increased linearly with dose, but with a slope 5 times steeper than that seen with normal cells. Sequence analysis of the {sup F} gene showed that 52 of 53 independent mutants generated in the XP variant cells contained base substitutions, with 62 of 64 of the substitutions involving a dipyrimidine.« less

Development of potent in vivo mutagenesis plasmids with broad mutational spectra

PubMed Central

Badran, Ahmed H.; Liu, David R.

2015-01-01

Methods to enhance random mutagenesis in cells offer advantages over in vitro mutagenesis, but current in vivo methods suffer from a lack of control, genomic instability, low efficiency and narrow mutational spectra. Using a mechanism-driven approach, we created a potent, inducible, broad-spectrum and vector-based mutagenesis system in E. coli that enhances mutation 322,000-fold over basal levels, surpassing the mutational efficiency and spectra of widely used in vivo and in vitro methods. We demonstrate that this system can be used to evolve antibiotic resistance in wild-type E. coli in <24 h, outperforming chemical mutagens, ultraviolet light and the mutator strain XL1-Red under similar conditions. This system also enables the continuous evolution of T7 RNA polymerase variants capable of initiating transcription using the T3 promoter in <10 h. Our findings enable broad-spectrum mutagenesis of chromosomes, episomes and viruses in vivo, and are applicable to both bacterial and bacteriophage-mediated laboratory evolution platforms. PMID:26443021

Development of potent in vivo mutagenesis plasmids with broad mutational spectra.

PubMed

Badran, Ahmed H; Liu, David R

2015-10-07

Methods to enhance random mutagenesis in cells offer advantages over in vitro mutagenesis, but current in vivo methods suffer from a lack of control, genomic instability, low efficiency and narrow mutational spectra. Using a mechanism-driven approach, we created a potent, inducible, broad-spectrum and vector-based mutagenesis system in E. coli that enhances mutation 322,000-fold over basal levels, surpassing the mutational efficiency and spectra of widely used in vivo and in vitro methods. We demonstrate that this system can be used to evolve antibiotic resistance in wild-type E. coli in <24 h, outperforming chemical mutagens, ultraviolet light and the mutator strain XL1-Red under similar conditions. This system also enables the continuous evolution of T7 RNA polymerase variants capable of initiating transcription using the T3 promoter in <10 h. Our findings enable broad-spectrum mutagenesis of chromosomes, episomes and viruses in vivo, and are applicable to both bacterial and bacteriophage-mediated laboratory evolution platforms.

[Effect of long-wave ultraviolet light (UV-A) and medium-wave ultraviolet rays (UV-B) on human skin. Critical comparison].

PubMed

Raab, W

1980-04-15

When discussing the effects of ultraviolet radiation on human skin, one should carefully distinguish between the long wave ultraviolet light (UV-A) and the short wave radiations (UV-B and UV-C). Ultraviolet A induces immediate pigmentation but, if high energies are applied, a permanent pigmentation is elicited. This type of ultraviolet A-induced pigmentation has been called "spontaneous" pigmentation as no erythematous reaction is necessary to induce or accelerate melanine formation. Ultraviolet B provokes erythema and consecutive pigmentation. Upon chronic exposure, ultraviolet B causes the wellknown actinic damage of the skin and even provokes carcinoma. With exposures to the sunlight (global radiation), one should be most careful. The public must be informed extensively about the dangers of excessive sunbaths. The use of artificial "suns" with spectra between 260 and 400 nm is limited as it may cause the same type of damage as the global radiation. An exact schedule for use of artificial lamps is strongly recommended. After one cycle of exposures, an interruption is necessary until the next cycle of irradiations may start. Upon continual use for tanning of the skin, artificial lamps may provoke irreversible damage of the skin. Radiation sources with emission spectra of wavelengths between 315 and 400 nm exclusively are well suited for the induction of skin pigmentation (cosmetic use). Potent radiation such as UVASUN systems provoke a "pleasant" permanent pigmentation after exposures for less than one hour. The use of ultraviolet A (UV-A) does not carry any risk for the human skin.

INTERACTION OF X AND ULTRAVIOLET RADIATION IN PRODUCTION OF RECESSIVE LETHALS IN DROSOPHILA MELANOGASTER (in Italian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nicoletti, B.; Olivieri, G.

1962-01-01

The possibility that uv rays given to different biological systems before or after x rays could modify genetic or cytological effects is reviewed and discussed. Kaufmann and Hollaender's conclusions about the recovering effect of uv rays on chromosomal damage induced in Drosophila sperms by a pre-treatment of x rays are discussed and analyzed taking into accourt some general considerations. Preliminary results of similar experiments on the frequency of sex-linked recessive lethals induced after single and combined x + uv treatments in Drosophila sperms are reported. All our experiments indicate no effect of the uv treatment (at the given wave lengthsmore » and doses) in lowering the frequency of the x-ray-induced recessive lethals. On the contrary, there are some indications for a synergistic action between the two radiations. These results not in agreement with the generally accepted theory that uv rays do recover X-ray- induced chromosomal damages, could be expiained With the well established correlation between chromosomal rejoined breaks and genic mutations. (auth)« less

SC79 protects retinal pigment epithelium cells from UV radiation via activating Akt-Nrf2 signaling

PubMed Central

Cao, Guo-fan; Cao, Cong; Jiang, Qin

2016-01-01

Excessive Ultra-violet (UV) radiation causes oxidative damages and apoptosis in retinal pigment epithelium (RPE) cells. Here we tested the potential activity of SC79, a novel small molecule activator of Akt, against the process. We showed that SC79 activated Akt in primary and established (ARPE-19 line) RPE cells. It protected RPE cells from UV damages possibly via inhibiting cell apoptosis. Akt inhibition, via an Akt specific inhibitor (MK-2206) or Akt1 shRNA silence, almost abolished SC79-induced RPE cytoprotection. Further studies showed that SC79 activated Akt-dependent NF-E2-related factor 2 (Nrf2) signaling and inhibited UV-induced oxidative stress in RPE cells. Reversely, Nrf2 shRNA knockdown or S40T mutation attenuated SC79-induced anti-UV activity. For the in vivo studies, we showed that intravitreal injection of SC79 significantly protected mouse retina from light damages. Based on these results, we suggest that SC79 protects RPE cells from UV damages possibly via activating Akt-Nrf2 signaling axis. PMID:27517753

TRAIP promotes DNA damage response during genome replication and is mutated in primordial dwarfism

PubMed Central

Leitch, Andrea; Higgs, Martin R.; Bicknell, Louise S.; Yigit, Gökhan; Blackford, Andrew N.; Zlatanou, Anastasia; Mackenzie, Karen J.; Reddy, Kaalak; Halachev, Mihail; McGlasson, Sarah; Reijns, Martin A. M.; Fluteau, Adeline; Martin, Carol-Anne; Sabbioneda, Simone; Elcioglu, Nursel H.; Altmüller, Janine; Thiele, Holger; Greenhalgh, Lynn; Chessa, Luciana; Maghnie, Mohamad; Salim, Mahmoud; Bober, Michael B.; Nürnberg, Peter; Jackson, Stephen P.; Hurles, Matthew E.; Wollnik, Bernd; Stewart, Grant S.; Jackson, Andrew P.

2015-01-01

DNA lesions encountered by replicative polymerases threaten genome stability and cell cycle progression. Here we report the identification of mutations in TRAIP, encoding an E3 RING ubiquitin ligase, in patients with microcephalic primordial dwarfism/Seckel syndrome. We establish that TRAIP relocalizes to sites of DNA damage where it is required for optimal phosphorylation of H2AX and RPA2 during S-phase in response to UV irradiation, as well as fork progression through UV-induced DNA lesions. TRAIP is necessary for efficient cell cycle progression and mutations in TRAIP therefore limit cellular proliferation, providing a potential mechanism for microcephaly and dwarfism phenotypes. Human genetics thus identifies TRAIP as a novel component of the DNA damage response to replication-blocking DNA lesions. PMID:26595769

Mutation and repair in an ultraviolet-sensitive Chinese hamster ovary cell line

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wood, R.D.

1981-11-01

An ultraviolet (UV) light-sensitive mutant of Chinese hamster ovary cells (CHO) has been isolated and characterized with respect to a number of post-irradiation responses. The UV-sensitive mutant, termed 43-3B, has the same growth rate and chromosome number as the wild-type CHO-9. 43-3B is hypersensitive to the lethal effects of UV light (D/sub 0/ of 0.3 J/m/sup 2/ as compared to 3.2 J/m/sup 2/ for the wild-type). A marked UV-hypermutability is observed in 43-3B as compared to the wild-type, as measured with markers for induced resistance to 6-thioguanine, ouabain, and diphtheria toxin. A factor of 38 to 65 more mutations aremore » induced per unit fluence in 43-3B than in CHO-9. The UV-sensitive mutant is also sensitive to killing by simulated solar light, although the D/sub 0/ ratio is not as great as for germicidal UV. 43-3B exhibits only about 17% of the wild-type level of UV-stimulated DNA repair synthesis, as measured by autoradiography of G/sub 1/ phase cells. A much reduced ability to recover control rates of semiconservative DNA synthesis after UV irradiation was observed in the repair-deficient 43-3B cell line. Recovery of colony-forming ability between fractionated UV exposures was observed in the wild-type CHO-9, but little recovery was seen in 43-3B. The present investigation demonstrates that a sensitive/wild-type pair of CHO cell lines can be used in comparative studies to determine the involvement of repair in a wide range of post-irradiation phenomena.« less

Epigenetic and genetic dissections of UV-induced global gene dysregulation in skin cells through multi-omics analyses

PubMed Central

Shen, Yao; Stanislauskas, Milda; Li, Gen; Zheng, Deyou; Liu, Liang

2017-01-01

To elucidate the complex molecular mechanisms underlying the adverse effects UV radiation (UVR) on skin homeostasis, we performed multi-omics studies to characterize UV-induced genetic and epigenetic changes. Human keratinocytes from a single donor treated with or without UVR were analyzed by RNA-seq, exome-seq, and H3K27ac ChIP-seq at 4 h and 72 h following UVR. Compared to the relatively moderate mutagenic effects of UVR, acute UV exposure induced substantial epigenomic and transcriptomic alterations, illuminating a previously underappreciated role of epigenomic and transcriptomic instability in skin pathogenesis. Integration of the multi-omics data revealed that UVR-induced transcriptional dysregulation of a subset of genes was attributable to either genetic mutations or global redistribution of H3K27ac. H3K27ac redistribution further led to the formation of distinctive super enhancers in UV-irradiated cells. Our analysis also identified several new UV target genes, including CYP24A1, GJA5, SLAMF7 and ETV1, which were frequently dysregulated in human squamous cell carcinomas, highlighting their potential as new molecular targets for prevention or treatment of UVR-induced skin cancers. Taken together, our concurrent multi-omics analyses provide new mechanistic insights into the complex molecular networks underlying UV photobiological effects, which have important implications in understanding its impact on skin homeostasis and pathogenesis. PMID:28211524

Pulsed UV laser-induced modifications in optical and structural characteristics of alpha-irradiated PM-355 SSNTD.

PubMed

Alghamdi, S S; Farooq, W A; Baig, M R; Algarawi, M S; Alrashidi, Talal Mohammed; Ali, Syed Mansoor; Alfaramawi, K

2017-10-01

Pre- and postalpha-exposed PM-355 detectors were irradiated using UV laser with different number of pulses (100, 150, 200, 300, and 400). UV laser beam energy of 20mJ per pulse with a pulse width of 9ns was incident on an area of 19.6mm 2 of the samples. XRD spectra indicated that for both reference and UV-irradiated samples, the structure is amorphous, but the crystallite size increases upon UV irradiation. The same results were obtained from SEM analysis. Optical properties of PM-355 polymeric solid-state nuclear track detectors were also investigated. Absorbance measurements for all PM-355 samples in the range of 200-400nm showed that the absorption edge had a blue shift up to a certain value, and then, it had an oscillating behavior. Photoluminescence spectra of PM-355 at 250nm revealed a decrease in the broadband peak intensity as a function of the number of UV pulses, while the wavelengths corresponding to the peaks had random shifts. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ultraviolet laser effects on the cornea

NASA Astrophysics Data System (ADS)

Zuclich, Joseph A.

1990-07-01

Ultraviolet radiation in the ambient environment or from artificial sources may pose both acute and chronic hazards to the skin and the ocular tissues. In general terrestrial conditions have evolved such that there are only narrow safety margins between ambient UV levels and exposure levels harmful to the human. Obvious examples of acute consequences ofUV overexposure are sunburn and snowblindness as well as analogous conditions induced by artificial sources such as the welder''s arc mercury vapor lamps and UV-emitting lasers. Further chronic UV exposure is strongly implicated as a causative agent in certain types of cataract and skin cancer. This presentation will summarize a number of specific cases where UV radiation affected the primate cornea. Data presented will include the action spectra for far- and near-UV induced ocular damage the pulsewidth and total energy dependencies of ocular thresholds studies of cumulative effects of repeated UV exposures and quantitative determinations of tissue repair or recovery rates. Depending on the exposure parameters utilized photochemical thermal or photoablative damage mechanisms may prevail. 1.

A Phase II Randomized Placebo-Controlled Trial of Oral N-acetylcysteine for Protection of Melanocytic Nevi against UV-Induced Oxidative Stress In Vivo.

PubMed

Cassidy, Pamela B; Liu, Tong; Florell, Scott R; Honeggar, Matthew; Leachman, Sancy A; Boucher, Kenneth M; Grossman, Douglas

2017-01-01

Oxidative stress plays a role in UV-induced melanoma, which may arise from melanocytic nevi. We investigated whether oral administration of the antioxidant N-acetylcysteine (NAC) could protect nevi from oxidative stress in vivo in the setting of acute UV exposure. The minimal erythemal dose (MED) was determined for 100 patients at increased risk for melanoma. Patients were randomized to receive a single dose (1,200 mg) of NAC or placebo, in double-blind fashion, and then one nevus was irradiated (1-2 MED) using a solar simulator. One day later, the MED was redetermined and the irradiated nevus and a control unirradiated nevus were removed for histologic analysis and examination of biomarkers of NAC metabolism and UV-induced oxidative stress. Increased expression of 8-oxoguanine, thioredoxin reductase-1, and γ-glutamylcysteine synthase modifier subunit were consistently seen in UV-treated compared with unirradiated nevi. However, no significant differences were observed in these UV-induced changes or in the pre- and postintervention MED between those patients receiving NAC versus placebo. Similarly, no significant differences were observed in UV-induced changes between subjects with germline wild-type versus loss-of-function mutations in the melanocortin-1 receptor. Nevi showed similar changes of UV-induced oxidative stress in an open-label post-trial study in 10 patients who received NAC 3 hours before nevus irradiation. Thus, a single oral dose of NAC did not effectively protect nevi from UV-induced oxidative stress under the conditions examined. Cancer Prev Res; 10(1); 36-44. ©2016 AACR. ©2016 American Association for Cancer Research.

Spatial correlation between chemical and topological defects in vitreous silica: UV-resonance Raman study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saito, M., E-mail: makina.saito@elettra.eu; D’Amico, F.; Bencivenga, F.

2014-06-28

A spatial correlation between chemical and topological defects in the tetrahedron network in vitreous silica produced by a fusion process of natural quartz crystals was found by synchrotron-based UV resonance Raman experiments. Furthermore, a quantitative correlation between these defects was obtained by comparing visible Raman and UV absorption spectra. These results indicate that in vitreous silica produced by the fusion process the topological defects disturb the surrounding tetrahedral silica network and induce further disorder regions with sub nanometric sizes.

Colloidal silver nanoparticles prepared by UV-light induced citrate reduction technique for the quantitative detection of uric acid

NASA Astrophysics Data System (ADS)

Maity, Anupam; Panda, Sovan Kumar

2018-04-01

Reddish-yellow color colloid consisting of silver nanoparticles (Ag NPs) has been synthesized by reducing aqueous AgNO3 solution by photo-induced citrate reduction technique under UV light. As prepared colloid exhibits single and intense plasmonic absorption peak in the violet region of the visible spectra with the peak centered at 405 nm. The NPs are fine and spherical with diameter ranging from 5 to 10 nm. These colloidal NPs have been used for the quantitative detection of uric acid by UV-VIS spectroscopy. A linear red shifting of the characteristics Plasmonic absorption peak of Ag NPs is observed with uric acid concentration. Uric acid can be detected by UV-VIS spectroscopy down to 5 nM limit using the prepared colloid.

An ultraviolet and visible spectroscopic study of a pulsational cycle of RY Sagittarii

NASA Technical Reports Server (NTRS)

Clayton, Geoffrey C.; Lawson, W. A.; Cottrell, P. L.; Whitney, Barbara A.; Stanford, S. Adam; De Ruyter, Frank

1994-01-01

High-dispersion visible and ultraviolet spectra and UBVRI photometry, covering a complete pulsation of the R Coronae Borealis star RY Sgr, have been obtained. The UV spectra were the first high-dispersion data ever obtained for the star. Together these observations comprise the most complete data set covering an RCB star pulsation cycle. The cycle observed was somewhat anomalous as it was affected by a second 55 day pulsation period as well as the primary 38 day period. However, the visible spectra showed the typical line splitting and radial velocity variations which have been observed previously. The simultaneous UV spectra showed much smaller, and phase-shifted, velocity variations than those seen in the visible. No evidence was seen of shock-induced emission at Mg II. These observations provide some support for the models of pulsating hydrogen deficient stars developed by Saio & Wheeler.

The mechanism of untargeted mutagenesis in UV-irradiated yeast.

PubMed

Lawrence, C W; Christensen, R B

1982-01-01

The SOS error-prone repair hypothesis proposes that untargeted and targeted mutations in E. coli both result from the inhibition of polymerase functions that normally maintain fidelity, and that this is a necessary precondition for translesion synthesis. Using mating experiments with excision deficient strains of Bakers' yeast, Saccharomyces cerevisiae, we find that up to 40% of cycl-91 revertants induced by UV are untargeted, showing that a reduction in fidelity is also found in irradiated cells of this organism. We are, however, unable to detect the induction or activation of any diffusible factor capable of inhibiting fidelity, and therefore suggest that untargeted and targeted mutations are the consequence of largely different processes. We propose that these observations are best explained in terms of a limited fidelity model. Untargeted mutations are thought to result from the limited capacity of processes which normally maintain fidelity, which are active during replication on both irradiated and unirradiated templates. Even moderate UV fluences saturate this capacity, leading to competition for the limited resource. Targeted mutations are believed to result from the limited, though far from negligible, capacity of lesions like pyrimidine dimers to form Watson-Crick base pairs.

Faster DNA Repair of Ultraviolet-Induced Cyclobutane Pyrimidine Dimers and Lower Sensitivity to Apoptosis in Human Corneal Epithelial Cells than in Epidermal Keratinocytes

PubMed Central

Mallet, Justin D.; Bastien, Nathalie; Gendron, Sébastien P.; Rochette, Patrick J.

2016-01-01

Absorption of UV rays by DNA generates the formation of mutagenic cyclobutane pyrimidine dimers (CPD) and pyrimidine (6–4) pyrimidone photoproducts (6-4PP). These damages are the major cause of skin cancer because in turn, they can lead to signature UV mutations. The eye is exposed to UV light, but the cornea is orders of magnitude less prone to UV-induced cancer. In an attempt to shed light on this paradox, we compared cells of the corneal epithelium and the epidermis for UVB-induced DNA damage frequency, repair and cell death sensitivity. We found similar CPD levels but a 4-time faster UVB-induced CPD, but not 6-4PP, repair and lower UV-induced apoptosis sensitivity in corneal epithelial cells than epidermal. We then investigated levels of DDB2, a UV-induced DNA damage recognition protein mostly impacting CPD repair, XPC, essential for the repair of both CPD and 6-4PP and p53 a protein upstream of the genotoxic stress response. We found more DDB2, XPC and p53 in corneal epithelial cells than in epidermal cells. According to our results analyzing the protein stability of DDB2 and XPC, the higher level of DDB2 and XPC in corneal epithelial cells is most likely due to an increased stability of the protein. Taken together, our results show that corneal epithelial cells have a better efficiency to repair UV-induced mutagenic CPD. On the other hand, they are less prone to UV-induced apoptosis, which could be related to the fact that since the repair is more efficient in the HCEC, the need to eliminate highly damaged cells by apoptosis is reduced. PMID:27611318

Evaporation of Particle-Stabilized Emulsion Sunscreen Films.

PubMed

Binks, Bernard P; Fletcher, Paul D I; Johnson, Andrew J; Marinopoulos, Ioannis; Crowther, Jonathan M; Thompson, Michael A

2016-08-24

We recently showed (Binks et al., ACS Appl. Mater. Interfaces, 2016, DOI: 10.1021/acsami.6b02696) how evaporation of sunscreen films consisting of solutions of molecular UV filters leads to loss of UV light absorption and derived sun protection factor (SPF). In the present work, we investigate evaporation-induced effects for sunscreen films consisting of particle-stabilized emulsions containing a dissolved UV filter. The emulsions contained either droplets of propylene glycol (PG) in squalane (SQ), droplets of SQ in PG or droplets of decane in PG. In these different emulsion types, the SQ is involatile and shows no evaporation, the PG is volatile and evaporates relatively slowly, whereas the decane is relatively very volatile and evaporates quickly. We have measured the film mass and area, optical micrographs of the film structure, and the UV absorbance spectra during evaporation. For emulsion films containing the involatile SQ, evaporation of the PG causes collapse of the emulsion structure with some loss of specular UV absorbance due to light scattering. However, for these emulsions with droplets much larger than the wavelength of light, the light is scattered only at small forward angles so does not contribute to the diffuse absorbance and the film SPF. The UV filter remains soluble throughout the evaporation and thus the UV absorption by the filter and the SPF remain approximately constant. Both PG-in-SQ and SQ-in-PG films behave similarly and do not show area shrinkage by dewetting. In contrast, the decane-in-PG film shows rapid evaporative loss of the decane, followed by slower loss of the PG resulting in precipitation of the UV filter and film area shrinkage by dewetting which cause the UV absorbance and derived SPF to decrease. Measured UV spectra during evaporation are in reasonable agreement with spectra calculated using models discussed here.

The circadian clock controls sunburn apoptosis and erythema in mouse skin.

PubMed

Gaddameedhi, Shobhan; Selby, Christopher P; Kemp, Michael G; Ye, Rui; Sancar, Aziz

2015-04-01

Epidemiological studies of humans and experimental studies with mouse models suggest that sunburn resulting from exposure to excessive UV light and damage to DNA confers an increased risk for melanoma and non-melanoma skin cancer. Previous reports have shown that both nucleotide excision repair, which is the sole pathway in humans for removing UV photoproducts, and DNA replication are regulated by the circadian clock in mouse skin. Furthermore, the timing of UV exposure during the circadian cycle has been shown to affect skin carcinogenesis in mice. Because sunburn and skin cancer are causally related, we investigated UV-induced sunburn apoptosis and erythema in mouse skin as a function of circadian time. Interestingly, we observed that sunburn apoptosis, inflammatory cytokine induction, and erythema were maximal following an acute early-morning exposure to UV and minimal following an afternoon exposure. Early-morning exposure to UV also produced maximal activation of ataxia telangiectasia mutated and Rad3-related (Atr)-mediated DNA damage checkpoint signaling, including activation of the tumor suppressor p53, which is known to control the process of sunburn apoptosis. These data provide early evidence that the circadian clock has an important role in the erythemal response in UV-irradiated skin. The early morning is when DNA repair is at a minimum, and thus the acute responses likely are associated with unrepaired DNA damage. The prior report that mice are more susceptible to skin cancer induction following chronic irradiation in the AM, when p53 levels are maximally induced, is discussed in terms of the mutational inactivation of p53 during chronic irradiation.

Spectrum of cisplatin-induced mutations in Escherichia coli

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burnouf, D.; Duane, M.; Fuchs, R.P.

1987-06-01

Using a forward-mutation assay based on the inactivation of the tetracycline-resistance gene located on plasmid pBR322, we have determined the mutation spectrum induced in Escherichia coli by cisplatin (cis-diamminedichloroplatinum(II)), a widely used antitumor drug. Cisplatin is known to form mainly intrastrand diadducts at ApG and GpG sites. We found that cisplatin efficiently induces mutations in an SOS-dependent way (i.e., dependent upon UV irradiation of the host bacteria). More than 90% of the mutations are single-base-pair substitutions occurring at the potential sites of cisplatin adducts (ApG and GpG). Taking into account the relative proportions of ApG and GpG adducts, we foundmore » that the ApG adducts are at least 5 times more mutagenic than the GpG adducts. Moreover, a strong mutation specificity was seen at the 5' side of the ApG adducts (A X T----T X A transversions). The observation that most mutations occur at the 5' end of the adduct at both ApG and GpG sites is discussed in relation to recent structural data.« less

Chronic low-dose ultraviolet-induced mutagenesis in nucleotide excision repair-deficient cells.

PubMed

Haruta, Nami; Kubota, Yoshino; Hishida, Takashi

2012-09-01

UV radiation induces two major types of DNA lesions, cyclobutane pyrimidine dimers (CPDs) and 6-4 pyrimidine-pyrimidine photoproducts, which are both primarily repaired by nucleotide excision repair (NER). Here, we investigated how chronic low-dose UV (CLUV)-induced mutagenesis occurs in rad14Δ NER-deficient yeast cells, which lack the yeast orthologue of human xeroderma pigmentosum A (XPA). The results show that rad14Δ cells have a marked increase in CLUV-induced mutations, most of which are C→T transitions in the template strand for transcription. Unexpectedly, many of the CLUV-induced C→T mutations in rad14Δ cells are dependent on translesion synthesis (TLS) DNA polymerase η, encoded by RAD30, despite its previously established role in error-free TLS. Furthermore, we demonstrate that deamination of cytosine-containing CPDs contributes to CLUV-induced mutagenesis. Taken together, these results uncover a novel role for Polη in the induction of C→T transitions through deamination of cytosine-containing CPDs in CLUV-exposed NER deficient cells. More generally, our data suggest that Polη can act as both an error-free and a mutagenic DNA polymerase, depending on whether the NER pathway is available to efficiently repair damaged templates.

Particle-fluorescence spectrometer for real-time single-particle measurements of atmospheric organic carbon and biological aerosol.

PubMed

Pan, Yong-Le; Pinnick, Ronald G; Hill, Steven C; Chang, Richard K

2009-01-15

A particle-fluorescence spectrometer (PFS) for real-time measurements of single-particle UV-laser-induced fluorescence (UV-LIF) excited with a pulsed (263-nm) laser is reported. The dispersed UV-LIF spectra are measured by a 32-anode PMT detector with spectral coverage from 280-600 nm. The PFS represents a significant improvement over our previous apparatus [Pinnick et al., Atmos. Environ. 2004, 38, 1657] and can (1) measure fluorescence spectra of bacterial particles having light-scattering sizes as small as 1 microm (previously limited to about 3 microm) and so can measure particles with size in the range of 1-10 microm, (2) measure each particle's elastic scattering which can be used to estimate particle size (not available previously), (3) measure single-particle fluorescence spectra with a laser and detector that can record spectra as fast as 90,000/s, although the highest rates we have found experimentally in atmospheric measurements is only several hundred per second (previously limited by detectors to only 25/s), and (4) provide a time stamp for a data block of spectra with time resolution from 10 ms to 10 min. In addition, the PFS has been modified to be more robust, transportable, and smaller. The use of an aerodynamic-focusing sheath inlet nozzle assembly has improved the sample rate. The PFS has been employed to measure UV-LIF spectra from individual atmospheric particles during October-December 2006 and January-May 2008 in New Haven, CT, and during January-May 2007 in Las Cruces, NM.

Sequencing analysis of mutations induced by N-ethyl-N-nitrosourea at different sampling times in mouse bone marrow.

PubMed

Wang, Jianyong; Chen, Tao

2010-03-01

In our previous study (Wang et al., 2004, Toxicol. Sci. 82: 124-128), we observed that the cII gene mutant frequency (MF) in the bone marrow of Big Blue mice showed significant increase as early as day 1, reached the maximum at day 3 and then decreased to a plateau by day 15 after a single dose of carcinogen N-ethyl-N-nitrosourea (ENU) treatment, which is different from the longer mutation manifestation time and the constancy of MFs after reaching their maximum in some other tissues. To determine the mechanism underlying the quick increase in MF and the peak formation in the mutant manifestation, we examined the mutation frequencies and spectra of the ENU-induced mutants collected from different sampling times in this study. The cII mutants from days 1, 3 and 120 after ENU treatment were randomly selected from different animals. The mutation frequencies were 33, 217, 305 and 144 x 10(-6) for control, days 1, 3, and 120, respectively. The mutation spectra at days 1 and 3 were significantly different from that at day 120. Considering that stem cells are responsible for the ultimate MF plateau (day 120) and transit cells are accountable for the earlier MF induction (days 1 or 3) in mouse bone marrow, we conclude that transit cells are much more sensitive to mutation induction than stem cells in mouse bone marrow, which resulted in the specific mutation manifestation induced by ENU.

How Alterations in the Cdt1 Expression Lead to Gene Amplification in Breast Cancer

DTIC Science & Technology

2011-07-01

absence of extrinsic DNA damage. We measured the TLS activity by measuring the mutation frequency in a supF gene (in a shuttle vector) subjected to UV...induced DNA damage before its introduction into the cells. Error-prone TLS activity will mutate the supF gene , which is scored by a blue-white colony...Figure 4A). Sequencing of the mutant supF genes , revealed a mutation spectrum consistent with error prone TLS (Supplemental Table 1). Significantly

A method for multi-codon scanning mutagenesis of proteins based on asymmetric transposons.

PubMed

Liu, Jia; Cropp, T Ashton

2012-02-01

Random mutagenesis followed by selection or screening is a commonly used strategy to improve protein function. Despite many available methods for random mutagenesis, nearly all generate mutations at the nucleotide level. An ideal mutagenesis method would allow for the generation of 'codon mutations' to change protein sequence with defined or mixed amino acids of choice. Herein we report a method that allows for mutations of one, two or three consecutive codons. Key to this method is the development of a Mu transposon variant with asymmetric terminal sequences. As a demonstration of the method, we performed multi-codon scanning on the gene encoding superfolder GFP (sfGFP). Characterization of 50 randomly chosen clones from each library showed that more than 40% of the mutants in these three libraries contained seamless, in-frame mutations with low site preference. By screening only 500 colonies from each library, we successfully identified several spectra-shift mutations, including a S205D variant that was found to bear a single excitation peak in the UV region.

Carcinogen susceptibility is regulated by genome architecture and predicts cancer mutagenesis.

PubMed

García-Nieto, Pablo E; Schwartz, Erin K; King, Devin A; Paulsen, Jonas; Collas, Philippe; Herrera, Rafael E; Morrison, Ashby J

2017-10-02

The development of many sporadic cancers is directly initiated by carcinogen exposure. Carcinogens induce malignancies by creating DNA lesions (i.e., adducts) that can result in mutations if left unrepaired. Despite this knowledge, there has been remarkably little investigation into the regulation of susceptibility to acquire DNA lesions. In this study, we present the first quantitative human genome-wide map of DNA lesions induced by ultraviolet (UV) radiation, the ubiquitous carcinogen in sunlight that causes skin cancer. Remarkably, the pattern of carcinogen susceptibility across the genome of primary cells significantly reflects mutation frequency in malignant melanoma. Surprisingly, DNase-accessible euchromatin is protected from UV, while lamina-associated heterochromatin at the nuclear periphery is vulnerable. Many cancer driver genes have an intrinsic increase in carcinogen susceptibility, including the BRAF oncogene that has the highest mutation frequency in melanoma. These findings provide a genome-wide snapshot of DNA injuries at the earliest stage of carcinogenesis. Furthermore, they identify carcinogen susceptibility as an origin of genome instability that is regulated by nuclear architecture and mirrors mutagenesis in cancer. © 2017 The Authors.

The mutation studies of mutagen-sensitive and DNA repair mutants of Chinese hamster fibroblasts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schultz, R.A.; Chang, C.C.; Trosko, J.E.

1981-01-01

We have previously reported the isolation and partial characterization of DNA repair and/or mutagen-sensitive mutant Chinese hamster cell strains. Here we present the results of a detailed study of the ultraviolet light (UV)-induced mutability of one of these strains, UVs-7, and provide preliminary mutability data on two additional lines, UVr-23 and UVs-40. UVs-7 in extremely deficient in unscheduled DNA synthesis (UDS) but only slightly more sensitive to UV than the parental line. When examined for the UV-inducibility of mutants resistant to ouabain, 6-thioguanine, or diphtheria toxin, UVs-7 was found to be hypermutable at all three loci as compared to themore » parental line. The degree of hypermutability was not the same for any two loci. UVs-40, a highly UV-sensitive strain, was also found to be hypermutable at the ouabain-resistant (ouar) locus. UVr-23, which is UV-resistant and more proficient at UDS than the parental line, appeared to exhibit a tendency toward hypomutability at both the ouabain(ouar) and 6-thioguanine--resistant (6TGr) loci. Further characterization of all these lines should aid in delineating mammalian mechanisms of DNA repair and mutagenesis.« less

Sun exposure causes somatic second-hit mutations and angiofibroma development in tuberous sclerosis complex

PubMed Central

Tyburczy, Magdalena E.; Wang, Ji-an; Li, Shaowei; Thangapazham, Rajesh; Chekaluk, Yvonne; Moss, Joel; Kwiatkowski, David J.; Darling, Thomas N.

2014-01-01

Tuberous sclerosis complex (TSC) is characterized by the formation of tumors in multiple organs and is caused by germline mutation in one of two tumor suppressor genes, TSC1 and TSC2. As for other tumor suppressor gene syndromes, the mechanism of somatic second-hit events in TSC tumors is unknown. We grew fibroblast-like cells from 29 TSC skin tumors from 22 TSC subjects and identified germline and second-hit mutations in TSC1/TSC2 using next-generation sequencing. Eighteen of 22 (82%) subjects had a mutation identified, and 8 of the 18 (44%) subjects were mosaic with mutant allele frequencies of 0 to 19% in normal tissue DNA. Multiple tumors were available from four patients, and in each case, second-hit mutations in TSC2 were distinct indicating they arose independently. Most remarkably, 7 (50%) of the 14 somatic point mutations were CC>TT ultraviolet ‘signature’ mutations, never seen as a TSC germline mutation. These occurred exclusively in facial angiofibroma tumors from sun-exposed sites. These results implicate UV-induced DNA damage as a cause of second-hit mutations and development of TSC facial angiofibromas and suggest that measures to limit UV exposure in TSC children and adults should reduce the frequency and severity of these lesions. PMID:24271014

Swift UVOT Grism Observations of Nearby Type Ia Supernovae - I. Observations and Data Reduction

NASA Astrophysics Data System (ADS)

Pan, Y.-C.; Foley, R. J.; Filippenko, A. V.; Kuin, N. P. M.

2018-05-01

Ultraviolet (UV) observations of Type Ia supernovae (SNe Ia) are useful tools for understanding progenitor systems and explosion physics. In particular, UV spectra of SNe Ia, which probe the outermost layers, are strongly affected by the progenitor metallicity. In this work, we present 120 Neil Gehrels Swift Observatory UV spectra of 39 nearby SNe Ia. This sample is the largest UV (λ < 2900 Å) spectroscopic sample of SNe Ia to date, doubling the number of UV spectra and tripling the number of SNe with UV spectra. The sample spans nearly the full range of SN Ia light-curve shapes (Δm15(B) ≈ 0.6-1.8 mag). The fast turnaround of Swift allows us to obtain UV spectra at very early times, with 13 out of 39 SNe having their first spectra observed ≳ 1 week before peak brightness and the earliest epoch being 16.5 days before peak brightness. The slitless design of the Swift UV grism complicates the data reduction, which requires separating SN light from underlying host-galaxy light and occasional overlapping stellar light. We present a new data-reduction procedure to mitigate these issues, producing spectra that are significantly improved over those of standard methods. For a subset of the spectra we have nearly simultaneous Hubble Space Telescope UV spectra; the Swift spectra are consistent with these comparison data.

[Genetic control of mitotic crossing-over in yeasts. III. Induction by 8-methoxypsoralen and long-wave UV irradiation (lambda=365 nm)].

PubMed

Fedorova, I V; Marfin, S V

1982-02-01

The lethal effect of 8-methoxypsoralen (8-MOP) plus 365 nm light has been studied in haploid radiosensitive strains of Saccharomyces cerevisiae. The diploid of wild type and the diploid homozygous for the rad2 mutation (this mutation blocks the excision of UV-induced pyrimidine dimers) were more resistant to the lethal effect of 8-MOP plus 365 nm light than the haploid of wild type and rad2 haploid, respectively. The diploid homozygous for rad54 mutation (the mutation blocks the repair of double-strand breaks in DNA) was more sensitive than haploid rad54. The method of repeated irradiation allowed to study the capacity of radiosensitive diploids to remove monoadducts induced by 8-MOP in DNA. This process was very effective in diploids of wild type and in the rad54 rad54 diploid, while the rad2 rad2 diploid was characterized by nearly complete absence of monoadduct excision. The study of mitotic crossing over and mitotic segregation in yeast diploids, containing a pair of complementing alleles of the ade2 gene (red/pink) has shown a very high recombinogenic effect of 8-MOP plus 365 nm light. The rad2 mutation slightly increased the frequency of mitotic segregation and mitotic crossing over. The rad54 mutation decreased the frequency of mitotic segregation and entirely suppressed mitotic crossing over. The method of repeated irradiation showed that the cross-links, but not monoadducts, are the main cause of high recombinogenic effect of 8-MOP plus 365 nm light. The possible participation of different repair systems in recombinational processes induced by 8-MOP in yeast cells is discussed.

Mutations of Profilin-1 Associated with Amyotrophic Lateral Sclerosis Promote Aggregation Due to Structural Changes of Its Native State.

PubMed

Del Poggetto, Edoardo; Bemporad, Francesco; Tatini, Francesca; Chiti, Fabrizio

2015-11-20

The PFN1 gene, coding for profilin-1, has recently been associated with familial amyotrophic lateral sclerosis (fALS), as three mutations, namely C71G, M114T, and G118V, have been found in patients with familial forms of the disease and another, E117G, has been proposed to be a moderate risk factor for disease onset. In this work, we have purified the four profilin-1 variants along with the wild-type protein. The resulting aggregates appear to be fibrillar, to have a weak binding to ThT, and to possess a significant amount of intermolecular β-sheet structure. Using ThT fluorescence assays, far-UV circular dichroism, and dynamic light scattering, we found that all four variants have an aggregation propensity higher than that of the wild-type counterpart. In particular, the C71G mutation was found to induce the most dramatic change in aggregation, followed by the G118V and M114T substitutions and then the E117G mutation. Such a propensity was found not to strictly correlate with the conformational stability in this group of profilin-1 variants, determined using both urea-induced denaturation at equilibrium and folding/unfolding kinetics. However, it correlated with structural changes of the folded states, as monitored with far-UV circular dichroism, intrinsic fluorescence spectroscopy, ANS binding, acrylamide quenching, and dynamic light scattering. Overall, the results suggest that all four mutations increase the tendency of profilin-1 to aggregate and that such aggregation behavior is largely determined by the mutation-induced structural changes occurring in the folded state of the protein.

Molecular pathology of skin neoplasms of the head and neck.

PubMed

Kraft, Stefan; Granter, Scott R

2014-06-01

Skin neoplasms include the most common malignancies affecting humans. Many show an ultraviolet (UV)-induced pathogenesis and often affect the head and neck region. To review literature on cutaneous neoplasms that show a predilection for the head and neck region and that are associated with molecular alterations. Literature review. Common nonmelanoma skin cancers, such as basal and squamous cell carcinomas, show a UV-induced pathogenesis. Basal cell carcinomas are characterized by molecular alterations of the Hedgehog pathway, affecting patched and smoothened genes. While squamous cell carcinomas show UV-induced mutations in several genes, driver mutations are only beginning to be identified. In addition, certain adnexal neoplasms also predominantly affect the head and neck region and show interesting, recently discovered molecular abnormalities, or are associated with hereditary conditions whose molecular genetic pathogenesis is well understood. Furthermore, recent advances have led to an increased understanding of the molecular pathogenesis of melanoma. Certain melanoma subtypes, such as lentigo maligna melanoma and desmoplastic melanoma, which are more often seen on the chronically sun-damaged skin of the head and neck, show differences in their molecular signature when compared to the other more common subtypes, such as superficial spreading melanoma, which are more prone to occur at sites with acute intermittent sun damage. In summary, molecular alterations in cutaneous neoplasms of the head and neck are often related to UV exposure. Their molecular footprint often reflects the histologic tumor type, and familiarity with these changes will be increasingly necessary for diagnostic and therapeutic considerations.

Stability study of PbSe semiconductor nanocrystals over concentration, size, atmosphere, and light exposure.

PubMed

Dai, Quanqin; Wang, Yingnan; Zhang, Yu; Li, Xinbi; Li, Ruowang; Zou, Bo; Seo, JaeTae; Wang, Yiding; Liu, Manhong; Yu, William W

2009-10-20

Infrared-emitting PbSe nanocrystals are of increasing interest in both fundamental research and technical application. However, the practical applications are greatly limited by their poor stability. In this work, absorption and photoluminescence spectra of PbSe nanocrystals were utilized to observe the stability of PbSe nanocrystals over several conventional factors, that is, particle concentration, particle size, temperature, light exposure, contacting atmosphere, and storage forms (solution or solid powder). Both absorption and luminescence spectra of PbSe nanocrystals exposed to air showed dependence on particle concentration, size, and light exposure, which caused large and quick blue-shifts in the optical spectra. This air-contacted instability arising from the destructive oxidation and subsequent collision-induced decomposition was kinetically dominated and differed from the traditional thought that smaller particles with lower concentrations shrank fast. The photoluminescence emission intensity of the PbSe nanocrystal solution under ultraviolet (UV) exposure in air increased first and then decreased slowly; without UV irradiation, the emission intensity monotonously decreased over time. However, if stored under nitrogen, no obvious changes in absorption and photoluminescence spectra of the PbSe nanocrystals were observed even under UV exposure or upon being heated up to 100 degrees C.

UV-biosensor for visual indication of vitamin D synthesis

NASA Astrophysics Data System (ADS)

Orlova, T. N.; Terenetskaya, I. P.

2008-04-01

Excessive UV doses have adverse effects on human health, but proper amount of UV is beneficial for people and is essential in the natural production of vitamin D# in skin. Most of broadband UV-radiometers that have an output in sunburn units are incapable to record correctly the vitamin D synthetic capacity of sunlight because of the difference between the CIE erythema and 'Vitamin D synthesis' action spectra. The liquid-crystalline UV sensor based on provitamin D photoconversions has been developed for direct observation of vitamin D synthesis under UV irradiation. UV-induced transformation of provitamin D in cholesteric liquid-crystalline matrix is accompanied by the change of cholesteric pitch value in the LC cell. The developed UV biosensor makes possible both instrumental and visual monitoring of the vitamin D synthetic capacity of sunlight and/or artificial UV source.

Direct on-strip analysis of size- and time-resolved aerosol impactor samples using laser induced fluorescence spectra excited at 263 and 351 nm.

PubMed

Wang, Chuji; Pan, Yong-Le; James, Deryck; Wetmore, Alan E; Redding, Brandon

2014-04-11

We report a novel atmospheric aerosol characterization technique, in which dual wavelength UV laser induced fluorescence (LIF) spectrometry marries an eight-stage rotating drum impactor (RDI), namely UV-LIF-RDI, to achieve size- and time-resolved analysis of aerosol particles on-strip. The UV-LIF-RDI technique measured LIF spectra via direct laser beam illumination onto the particles that were impacted on a RDI strip with a spatial resolution of 1.2mm, equivalent to an averaged time resolution in the aerosol sampling of 3.6 h. Excited by a 263 nm or 351 nm laser, more than 2000 LIF spectra within a 3-week aerosol collection time period were obtained from the eight individual RDI strips that collected particles in eight different sizes ranging from 0.09 to 10 μm in Djibouti. Based on the known fluorescence database from atmospheric aerosols in the US, the LIF spectra obtained from the Djibouti aerosol samples were found to be dominated by fluorescence clusters 2, 5, and 8 (peaked at 330, 370, and 475 nm) when excited at 263 nm and by fluorescence clusters 1, 2, 5, and 6 (peaked at 390 and 460 nm) when excited at 351 nm. Size- and time-dependent variations of the fluorescence spectra revealed some size and time evolution behavior of organic and biological aerosols from the atmosphere in Djibouti. Moreover, this analytical technique could locate the possible sources and chemical compositions contributing to these fluorescence clusters. Advantages, limitations, and future developments of this new aerosol analysis technique are also discussed. Published by Elsevier B.V.

Applicability of UV laser-induced solid-state fluorescence spectroscopy for characterization of solid dosage forms.

PubMed

Woltmann, Eva; Meyer, Hans; Weigel, Diana; Pritzke, Heinz; Posch, Tjorben N; Kler, Pablo A; Schürmann, Klaus; Roscher, Jörg; Huhn, Carolin

2014-10-01

High production output of solid pharmaceutical formulations requires fast methods to ensure their quality. Likewise, fast analytical procedures are required in forensic sciences, for example at customs, to substantiate an initial suspicion. We here present the design and the optimization of an instrumental setup for rapid and non-invasive characterization of tablets by laser-induced fluorescence spectroscopy (with a UV-laser (λ ex = 266 nm) as excitation source) in reflection geometry. The setup was first validated with regard to repeatability, bleaching phenomena, and sensitivity. The effect on the spectra by the physical and chemical properties of the samples, e.g. their hardness, homogeneity, chemical composition, and granule grain size of the uncompressed material, using a series of tablets, manufactured in accordance with design of experiments, was investigated. Investigation of tablets with regard to homogeneity, especially, is extremely important in pharmaceutical production processes. We demonstrate that multiplicative scatter correction is an appropriate tool for data preprocessing of fluorescence spectra. Tablets with different physical and chemical characteristics can be discriminated well from their fluorescence spectra by subjecting the results to principal component analysis.

Kinetics of mutation induction by ultraviolet light in excision-deficient yeast.

PubMed

Eckardt, F; Haynes, R H

1977-02-01

We have measured the frequency of UV-induced reversions (locus plus suppressor) for the ochre alleles ade2-1 and lys2-1 and forward mutations (ade2 adex double auxotrophs) in an excision-deficient strain of Saccharomyces cerevisiae (rad2-20). For very low UV doses, both mutational systems exhibit linear induction kinetics. However, as the dose increases, a strikingly different response is observed: in the selective reversion system a transition to higher order induction kinetics occurs near 9 ergs/mm2 (25% survival), whereas in the nonselective forward system the mutation frequency passes through a maximum near 14 ergs/mm2 (4.4% survival) and then declines. This contrast in kinetics cannot be explained in any straightforward way by current models of induced mutagenesis, which have been developed primarily on the basis of bacterial data. The bacterial models are designed to accommodate the quadratic induction kinetics that are frequently observed in these systems. We have derived a mathematical expression for mutation frequency that enables us to fit both the forward and reversion data on the assumptions that mutagenesis is basically a "single event" Poisson process, and that mutation and killing are not necessarily independent of one another. In particular, the dose-response relations are consistent with the idea that the sensitivity of the revertants is about 25% less than that of the original cell population, whereas the sensitivity of the forward mutants is about 29% greater than the population average. We argue that this relatively small differential sensitivity of mutant and nonmutant cells is associated with events that take place during mutation expression and clonal growth.

Ionization-induced solvent migration in acetanilide-methanol clusters inferred from isomer-selective infrared spectroscopy.

PubMed

Weiler, Martin; Nakamura, Takashi; Sekiya, Hiroshi; Dopfer, Otto; Miyazaki, Mitsuhiko; Fujii, Masaaki

2012-12-07

We present the resonance-enhanced multiphoton ionization, infrared-ultraviolet hole burning (IR-UV HB), and IR dip spectra of the trans-acetanilide-methanol (AA-MeOH) cluster in the S(0), S(1), and cationic ground state (D(0)) in a supersonic jet. The IR-UV HB spectra demonstrate the co-existence of two isomers in S(0,1), in which MeOH binds either to the NH or the CO site of the peptide linkage in AA, denoted as AA(NH)-MeOH and AA(CO)-MeOH. When AA(CO)-MeOH is selectively ionized, its IR spectrum in D(0) is the same as that measured for AA(+) (NH)-MeOH. Thus, photoionization of AA(CO)-MeOH induces migration of MeOH from the CO to the NH site with 100% yield. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Dot1 and Set2 Histone Methylases Control the Spontaneous and UV-Induced Mutagenesis Levels in the Saccharomyces cerevisiae Yeasts].

PubMed

Kozhina, T N; Evstiukhina, T A; Peshekhonov, V T; Chernenkov, A Yu; Korolev, V G

2016-03-01

In the Saccharomyces cerevisiae yeasts, the DOT1 gene product provides methylation of lysine 79 (K79) of hi- stone H3 and the SET2 gene product provides the methylation of lysine 36 (K36) of the same histone. We determined that the dot1 and set2 mutants suppress the UV-induced mutagenesis to an equally high degree. The dot1 mutation demonstrated statistically higher sensitivity to the low doses of MMC than the wild type strain. The analysis of the interaction between the dot1 and rad52 mutations revealed a considerable level of spontaneous cell death in the double dot1 rad52 mutant. We observed strong suppression of the gamma-in- duced mutagenesis in the set2 mutant. We determined that the dot1 and set2 mutations decrease the sponta- neous mutagenesis rate in both single and d ouble mutants. The epistatic interaction between the dot1 and set2 mutations and almost similar sensitivity of the corresponding mutants to the different types of DNA damage allow one to conclude that both genes are involved in the control of the same DNA repair pathways, the ho- mologous-recombination-based and the postreplicative DNA repair.

UV-B-induced DNA damage and repair in the mouse lens.

PubMed

Mesa, Rosana; Bassnett, Steven

2013-10-17

Epidemiologic studies have linked UV-B exposure to development of cortical cataracts, but the underlying molecular mechanism(s) is unresolved. Here, we used a mouse model to examine the nature and distribution of DNA photolesions produced by ocular UV-B irradiation. Anesthetized mice, eye globes, or isolated lenses were exposed to UV-B. Antibodies specific for 6-4 photoproducts (6-4 PPs) or cyclobutane pyrimidine dimers (CPDs) were used to visualize DNA adducts. Illumination of intact globes with UV-B-induced 6-4 PP and CPD formation in cells of the cornea, anterior iris, and central lens epithelium. Photolesions were not detected in retina or lens cells situated in the shadow of the iris. Photolesions in lens epithelial cells were produced with radiant exposures significantly below the minimal erythemal dose. Lens epithelial cells rapidly repaired 6-4 PPs, but CPD levels did not markedly diminish, even over extended postirradiation recovery periods in vitro or in vivo. The repair of 6-4 PPs did not depend on the proliferative activity of the epithelial cells, since the repair rate in the mitotically-active germinative zone (GZ) was indistinguishable from that of quiescent cells in the central epithelium. Even relatively modest exposures to UV-B produced 6-4 PP and CPD photolesions in lens epithelial cells. Cyclobutane pyrimidine dimer lesions were particularly prevalent and were repaired slowly if at all. Studies on sun-exposed skin have established a causal connection between photolesions and so-called UV-signature mutations. If similar mechanisms apply in the lens, it suggests that somatic mutations in lens epithelial cells may contribute to the development of cortical cataracts.

Comparative evaluation of differential laser-induced perturbation spectroscopy as a technique to discriminate emerging skin pathology

NASA Astrophysics Data System (ADS)

Kozikowski, Raymond T.; Smith, Sarah E.; Lee, Jennifer A.; Castleman, William L.; Sorg, Brian S.; Hahn, David W.

2012-06-01

Fluorescence spectroscopy has been widely investigated as a technique for identifying pathological tissue; however, unrelated subject-to-subject variations in spectra complicate data analysis and interpretation. We describe and evaluate a new biosensing technique, differential laser-induced perturbation spectroscopy (DLIPS), based on deep ultraviolet (UV) photochemical perturbation in combination with difference spectroscopy. This technique combines sequential fluorescence probing (pre- and post-perturbation) with sub-ablative UV perturbation and difference spectroscopy to provide a new spectral dimension, facilitating two improvements over fluorescence spectroscopy. First, the differential technique eliminates significant variations in absolute fluorescence response within subject populations. Second, UV perturbations alter the extracellular matrix (ECM), directly coupling the DLIPS response to the biological structure. Improved biosensing with DLIPS is demonstrated in vivo in a murine model of chemically induced skin lesion development. Component loading analysis of the data indicates that the DLIPS technique couples to structural proteins in the ECM. Analysis of variance shows that DLIPS has a significant response to emerging pathology as opposed to other population differences. An optimal likelihood ratio classifier for the DLIPS dataset shows that this technique holds promise for improved diagnosis of epithelial pathology. Results further indicate that DLIPS may improve diagnosis of tissue by augmenting fluorescence spectra (i.e. orthogonal sensing).

UV-vis spectra as an alternative to the Lowry method for quantify hair damage induced by surfactants.

PubMed

Pires-Oliveira, Rafael; Joekes, Inés

2014-11-01

It is well known that long term use of shampoo causes damage to human hair. Although the Lowry method has been widely used to quantify hair damage, it is unsuitable to determine this in the presence of some surfactants and there is no other method proposed in literature. In this work, a different method is used to investigate and compare the hair damage induced by four types of surfactants (including three commercial-grade surfactants) and water. Hair samples were immersed in aqueous solution of surfactants under conditions that resemble a shower (38 °C, constant shaking). These solutions become colored with time of contact with hair and its UV-vis spectra were recorded. For comparison, the amount of extracted proteins from hair by sodium dodecyl sulfate (SDS) and by water were estimated by the Lowry method. Additionally, non-pigmented vs. pigmented hair and also sepia melanin were used to understand the washing solution color and their spectra. The results presented herein show that hair degradation is mostly caused by the extraction of proteins, cuticle fragments and melanin granules from hair fiber. It was found that the intensity of solution color varies with the charge density of the surfactants. Furthermore, the intensity of solution color can be correlated to the amount of proteins quantified by the Lowry method as well as to the degree of hair damage. UV-vis spectrum of hair washing solutions is a simple and straightforward method to quantify and compare hair damages induced by different commercial surfactants. Copyright © 2014 Elsevier B.V. All rights reserved.

Uv Spectroscopy on Gas Phase Cu(I)-BIPYRIDYL Complexes

NASA Astrophysics Data System (ADS)

Xu, Shuang; Christopher, Casey; Weber, J. Mathias

2015-06-01

Transition metal complexes with bipyridine ligands are of great interest in metal-organic chemistry, since they are prototypes for many applications in photochemistry and homogeneous catalysis. Under-coordinated bipyridyl complexes are elusive species in the condensed phase, and the ligand-induced changes in electronic structure are of fundamental interest. We present UV photodissociation spectra of mass-selected monocationic copper(I)-bipyridyl complexes [bpy-Cu-L]+ with different ligands (L = H2O, D2, N2, MeOH, Cl). Complexes were prepared via electrospray ionization of copper/bipyridine solutions followed by accumulation and buffer gas cooling in a cryogenic Paul trap. In addition, we show spectra of similar species based on copper oxide, [bpy-CuO-L]+.

Mutational spectra of the lacI transgene isolated from Big Blue{reg_sign} mice exposed to three carcinogenic aromatic amines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Staedtler, F.; Locher, F.; Sreenan, G.

1997-10-01

In order to evaluate the in vivo genotoxic potential of three putative genotoxic mouse liver carcinogens, high doses of 4-chloro-o-phenylenediamine, 2-nitro-p-phenylenediamine and 2, 4-diaminotoluene were tested short term in the Big Blue{reg_sign} transgenic mouse mutation assay. Small statistically significant increases in the lacI mutant frequencies in the liver by factors 1.7 to 2.0 were found. A representative number of 347 lacI mutants isolated from liver tissue of male and female animals were analyses by DNA sequencing. The mutational spectra were examined with the Adams-Skopek algorithm. The spontaneous mutational spectra from untreated male and female animals were similar and consistent withmore » spectral Big Blue{reg_sign} control data stored in the lacI database. Most of the background mutations were located in the 5{prime} portion of the coding region of the lacI gene. Single base substitutions were most prominent. G:C to A:T transitions and G:C to T:A transversions occurred predominatly and were preferentially located at CpG sites. Despite the increases observed in the mutant frequencies of the treated animals, the corresponding mutational spectra did not differ from the controls. However, it is possible that certain classes of point mutations were substantially increased but not detected due to the limited number of sequenced mutants. In two animals treated with 2, 4- diaminotoluene unusually high mutant frequencies and the multiple occurrence of certain mutations in the liver was observed. From one of these animals six lacI mutants isolated from colon tissue were all different. Since 2, 4-diaminotoluene was shown to induce liver cell proliferation these results may reflect clonal expansion of single mutated liver cells.« less

Ultraviolet Spectra of Two Magnetic White Dwarfs and Ultraviolet Spectra of Subluminous Objects Found in the Kiso Schmidt Survey and Ultraviolet Absorptions in the Spectra of DA White Dwarfds

NASA Technical Reports Server (NTRS)

Wegner, Gary A.

1988-01-01

Research under NASA Grant NAG5-287 has carried out a number of projects in conjunction with the International Ultraviolet Explorer (IUE) satellite. These include: (1) studies of the UV spectra of DA white dwarfs which show quasi-molecular bands of H2 and H2(+); (2) the peculiar star HR6560; (3) the UV spectra of two magnetic white dwarfs that also show the quasi-molecular features; (4) investigations of the UV spectra of subluminous stars, primarily identified from visual wavelength spectroscopy in the Kiso survey of UV excess stars, some of which show interesting metal lines in their UV spectra; and (5) completion of studies of UV spectra of DB stars. The main result of this research has been to further knowledge of the structure and compositions of subluminous stars which helps cast light on their formation and evolution.

Generation of DNA single-strand displacement by compromised nucleotide excision repair

PubMed Central

Godon, Camille; Mourgues, Sophie; Nonnekens, Julie; Mourcet, Amandine; Coin, Fréderic; Vermeulen, Wim; Mari, Pierre-Olivier; Giglia-Mari, Giuseppina

2012-01-01

Nucleotide excision repair (NER) is a precisely coordinated process essential to avoid DNA damage-induced cellular malfunction and mutagenesis. Here, we investigate the mechanistic details and effects of the NER machinery when it is compromised by a pathologically significant mutation in a subunit of the repair/transcription factor TFIIH, namely XPD. In contrast to previous studies, we find that no single- or double-strand DNA breaks are produced at early time points after UV irradiation of cells bearing a specific XPD mutation, despite the presence of a clear histone H2AX phosphorylation (γH2AX) signal in the UV-exposed areas. We show that the observed γH2AX signal can be explained by the presence of longer single-strand gaps possibly generated by strand displacement. Our in vivo measurements also indicate a strongly reduced TFIIH-XPG binding that could promote single-strand displacement at the site of UV lesions. This finding not only highlights the crucial role of XPG's interactions with TFIIH for proper NER, but also sheds new light on how a faulty DNA repair process can induce extreme genomic instability in human patients. PMID:22863773

SHINING A LIGHT ON XERODERMA PIGMENTOSUM

PubMed Central

DiGiovanna, John J.; Kraemer, Kenneth H.

2012-01-01

Xeroderma pigmentosum (XP) is a rare, autosomal recessive disorder of DNA repair characterized by sun sensitivity and ultraviolet (UV) induced skin and mucous membrane cancers. Described in 1874 by Moriz Kaposi in Vienna, nearly 100 years later James Cleaver in San Francisco reported defective DNA repair in XP cells. This eventually provided the basis for a mechanistic link between sun exposure, DNA damage, somatic mutations and skin cancer. XP cells were found to have defects in 7 of the proteins of the nucleotide excision repair pathway and in DNA polymerase eta. XP cells are hypersensitive to killing by UV and XP cancers have characteristic “UV signature” mutations. Clinical studies at NIH found a nearly 10,000-fold increase in skin cancer in XP patients under age 20 years demonstrating the substantial importance of DNA repair in cancer prevention in the general population. About 25 % of XP patients have progressive neurological degeneration with progressive loss of neurons, probably from DNA damage induced by oxidative metabolism which kills non-dividing cells in the nervous system. Interestingly, patients with another disorder, trichothiodystrophy have defects in some of the same genes as XP but they have primary developmental abnormalities without an increase in skin cancer. PMID:22217736

RADH, a gene of Saccharomyces cerevisiae encoding a putative DNA helicase involved in DNA repair. Characteristics of radH mutants and sequence of the gene.

PubMed

Aboussekhra, A; Chanet, R; Zgaga, Z; Cassier-Chauvat, C; Heude, M; Fabre, F

1989-09-25

A new type of radiation-sensitive mutant of S. cerevisiae is described. The recessive radH mutation sensitizes to the lethal effect of UV radiations haploids in the G1 but not in the G2 mitotic phase. Homozygous diploids are as sensitive as G1 haploids. The UV-induced mutagenesis is depressed, while the induction of gene conversion is increased. The mutation is believed to channel the repair of lesions engaged in the mutagenic pathway into a recombination process, successful if the events involve sister-chromatids but lethal if they involve homologous chromosomes. The sequence of the RADH gene reveals that it may code for a DNA helicase, with a Mr of 134 kDa. All the consensus domains of known DNA helicases are present. Besides these consensus regions, strong homologies with the Rep and UvrD helicases of E. coli were found. The RadH putative helicase appears to belong to the set of proteins involved in the error-prone repair mechanism, at least for UV-induced lesions, and could act in coordination with the Rev3 error-prone DNA polymerase.

Induction and prevention of micronuclei and chromosomal aberrations in cultured human lymphocytes exposed to the light of halogen tungsten lamps.

PubMed

D'Agostini, F; Caimo, A; De Filippi, S; De Flora, S

1999-07-01

Previous studies have shown that the light emitted by halogen tungsten lamps contains UV radiation in the UV-A, UV-B and UV-C regions, induces mutations and irreparable DNA damage in bacteria, enhances the frequency of micronuclei in cultured human lymphocytes and is potently carcinogenic to the skin of hairless mice. The present study showed that the light emitted by an uncovered, traditional halogen lamp induces a significant, dose-related and time-related increase not only in micronuclei but also in chromosome-type aberrations, such as breaks, and even more in chromatid-type aberrations, such as isochromatid breaks, exchanges and isochromatid/chromatid interchanges, all including gaps or not, in cultured human lymphocytes. All these genotoxic effects were completely prevented by shielding the same lamp with a silica glass cover, blocking UV radiation. A new model of halogen lamp, having the quartz bulb treated in order to reduce the output of UV radiation, was considerably less genotoxic than the uncovered halogen lamp, yet induction of chromosomal alterations was observed at high illuminance levels.

Suppression of the UV-sensitive phenotype of Escherichia coli recF mutants by recA(Srf) and recA(Tif) mutations requires recJ+.

PubMed Central

Thoms, B; Wackernagel, W

1988-01-01

Mutations in recA, such as recA801(Srf) (suppressor of RecF) or recA441(Tif) (temperature-induced filamentation) partially suppress the deficiency in postreplication repair of UV damage conferred by recF mutations. We observed that spontaneous recA(Srf) mutants accumulated in cultures of recB recC sbcB sulA::Mu dX(Ap lac) lexA51 recF cells because they grew faster than the parental strain. We show that in a uvrA recB+ recC+ genetic background there are two prerequisites for the suppression by recA(Srf) of the UV-sensitive phenotype of recF mutants. (i) The recA(Srf) protein must be provided in increased amounts either by SOS derepression or by a recA operator-constitutive mutation in a lexA(Ind) (no induction of SOS functions) genetic background. (ii) The gene recJ, which has been shown previously to be involved in the recF pathway of recombination and repair, must be functional. The level of expression of recJ in a lexA(Ind) strain suffices for full suppression. Suppression by recA441 at 30 degrees C also depends on recJ+. The hampered induction by UV of the SOS gene uvrA seen in a recF mutant was improved by a recA(Srf) mutation. This improvement did not require recJ+. We suggest that recA(Srf) and recA(Tif) mutant proteins can operate in postreplication repair independent of recF by using the recJ+ function. PMID:2841294

UV-induced bond modifications in thymine and thymine dideoxynucleotide: structural elucidation of isomers by differential mobility mass spectrometry.

PubMed

St-Jacques, Antony; Anichina, Janna; Schneider, Bradley B; Covey, Thomas R; Bohme, Diethard K

2010-07-15

Differential mobility spectrometry has been applied to reveal the occurrence of isomerization of thymine nucleobase and of thymine dideoxynucleotide d(5'-TT-3') due to bond redisposition induced by UV irradiation at 254 nm of frozen aqueous solutions of these molecules. Collision-induced dissociation (CID) spectra of electrosprayed photoproducts of the thymine solution suggest the presence of two isomers (the so-called cyclobutane and 6,4-photoproducts) in addition to the proton-bound thymine dimer, and these were separated using differential mobility spectrometry/mass spectrometry (DMS/MS) techniques with water as the modifier. Similar experiments with d(5'-TT-3') revealed the formation of a new isomer of deprotonated thymine dideoxynucleotide upon UV irradiation that was easily distinguished using DMS/MS with isopropanol as the modifier. The results reinforce the usefulness of DMS/MS in isomer separation.

Effects of different levels of vitamin C on UV radiation-induced DNA damage

NASA Astrophysics Data System (ADS)

Zhou, Dianfeng; Heng, Hang; Ji, Kang; Ke, Weizhong

2005-05-01

The Raman spectra of DNA in different levels of vitamin C with 10- and 30-min ultraviolet (UV) radiations were reported. The intensity of UV radiation was 18.68 W/m2. The experimental results proved that vitamin C could alone prevent UV radiation from damaging DNA, but the effects depended on the concentration of vitamin C. When the concentration of vitamin C was about 0.08-0.4 mmol/L, vitamin C decreased UV radiation-induced DNA's damage. When the concentration of vitamin C exceeded 0.4 mmol/L, vitamin C accelerated DNA's damage instead. Maybe the reason is that when DNA in aqueous solution is radiated by UV, free radicals come into being, and vitamin C can scavenge free radicals, so vitamin C in lower concentration can protect DNA. The quantity of free radicals is finite, when vitamin C is superfluous, free radicals have been scavenged absolutely and vitamin C is residual. Vitamin C is a strong reductant. When the mixture of DNA and residual vitamin C is radiated by UV, vitamin C reacts with DNA. The more residual vitamin C and the longer time of UV radiation, the more DNA is damaged.

Ursolic Acid-Regulated Energy Metabolism—Reliever or Propeller of Ultraviolet-Induced Oxidative Stress and DNA Damage?

PubMed Central

Lee, Yuan-Hao; Sun, Youping; Glickman, Randolph D.

2014-01-01

Ultraviolet (UV) light is a leading cause of diseases, such as skin cancers and cataracts. A main process mediating UV-induced pathogenesis is the production of reactive oxygen species (ROS). Excessive ROS levels induce the formation of DNA adducts (e.g., pyrimidine dimers) and result in stalled DNA replication forks. In addition, ROS promotes phosphorylation of tyrosine kinase-coupled hormone receptors and alters downstream energy metabolism. With respect to the risk of UV-induced photocarcinogenesis and photodamage, the antitumoral and antioxidant functions of natural compounds become important for reducing UV-induced adverse effects. One important question in the field is what determines the differential sensitivity of various types of cells to UV light and how exogenous molecules, such as phytochemicals, protect normal cells from UV-inflicted damage while potentiating tumor cell death, presumably via interaction with intracellular target molecules and signaling pathways. Several endogenous molecules have emerged as possible players mediating UV-triggered DNA damage responses. Specifically, UV activates the PIKK (phosphatidylinositol 3-kinase-related kinase) family members, which include DNA-PKcs, ATM (ataxia telangiectasia mutated) and mTOR (mammalian target of rapamycin), whose signaling can be affected by energy metabolism; however, it remains unclear to what extent the activation of hormone receptors regulates PIKKs and whether this crosstalk occurs in all types of cells in response to UV. This review focuses on proteomic descriptions of the relationships between cellular photosensitivity and the phenotypic expression of the insulin/insulin-like growth receptor. It covers the cAMP-dependent pathways, which have recently been shown to regulate the DNA repair machinery through interactions with the PIKK family members. Finally, this review provides a strategic illustration of how UV-induced mitogenic activity is modulated by the insulin sensitizer, ursolic acid (UA), which results in the metabolic adaptation of normal cells against UV-induced ROS, and the metabolic switch of tumor cells subject to UV-induced damage. The multifaceted natural compound, UA, specifically inhibits photo-oxidative DNA damage in retinal pigment epithelial cells while enhancing that in skin melanoma. Considering the UA-mediated differential effects on cell bioenergetics, this article reviews the disparities in glucose metabolism between tumor and normal cells, along with (peroxisome proliferator-activated receptor-γ coactivator 1α)-dependent mitochondrial metabolism and redox (reduction-oxidation) control to demonstrate UA-induced synthetic lethality in tumor cells. PMID:28250388

Activation of KGFR-Akt-mTOR-Nrf2 signaling protects human retinal pigment epithelium cells from Ultra-violet.

PubMed

Hu, Haitao; Hao, Lanxiang; Tang, Chunzhou; Zhu, Yunxi; Jiang, Qin; Yao, Jin

2018-01-15

Ultra-violet (UV) radiation causes oxidative injuries to human retinal pigment epithelium (RPE) cells. We tested the potential effect of keratinocyte growth factor (KGF) against the process. KGF receptor (KGFR) is expressed in ARPE-19 cells and primary human RPE cells. Pre-treatment with KGF inhibited UV-induced reactive oxygen species (ROS) production and RPE cell death. KGF activated nuclear-factor-E2-related factor 2 (Nrf2) signaling in RPE cells, causing Nrf2 Ser-40 phosphorylation, stabilization and nuclear translocation as well as expression of Nrf2-dependent genes (HO1, NOQ1 and GCLC). Nrf2 knockdown (by targeted shRNAs) or S40T mutation almost reversed KGF-induced RPE cell protection against UV. Further studies demonstrated that KGF activated KGFR-Akt-mTORC1 signaling to mediate downstream Nrf2 activation. KGFR shRNA or Akt-mTORC1 inhibition not only blocked KGF-induced Nrf2 Ser-40 phosphorylation and activation, but also nullified KGF-mediated RPE cell protection against UV. We conclude that KGF-KGFR activates Akt-mTORC1 downstream Nrf2 signaling to protect RPE cells from UV radiation. Copyright © 2017 Elsevier Inc. All rights reserved.

Spectrally resolved infrared microscopy and chemometric tools to reveal the interaction between blue light (470nm) and methicillin-resistant Staphylococcus aureus.

PubMed

Bumah, Violet V; Aboualizadeh, Ebrahim; Masson-Meyers, Daniela S; Eells, Janis T; Enwemeka, Chukuka S; Hirschmugl, Carol J

2017-02-01

Blue light inactivates methicillin-resistant Staphylococcus aureus (MRSA), a Gram-positive antibiotic resistant bacterium that leads to fatal infections; however, the mechanism of bacterial death remains unclear. In this paper, to uncover the mechanism underlying the bactericidal effect of blue light, a combination of Fourier transform infrared (FTIR) spectroscopy and chemometric tools is employed to detect the photoreactivity of MRSA and its distinctive pathway toward apoptosis after treatment. The mechanism of action of UV light and vancomycin against MRSA is also investigated to support the findings. Principal component analysis followed by linear discriminant analysis (PCA- LDA) is employed to reveal clustering of five groups of MRSA samples, namely untreated (control I), untreated and incubated at ambient air (control II), irradiated with 470nm blue light, irradiated with 253.5 UV light, and vancomycin-treated MRSA. Loadings plot from PCA-LDA analysis reveals important functional groups in proteins (1683, 1656, 1596, 1542cm -1 ), lipids (1743, 1409cm -1 ), and nucleic acids region of the spectrum (1060, 1087cm -1 ) that are responsible for the classification of blue light irradiated spectra and control spectra. Cluster vector plots and scores plot reveals that UV light-irradiated spectra are the most biochemically similar to blue light- irradiated spectra; however, some wavenumbers experience a shift. The shifts between blue light and UV light irradiated loadings plot at ν asym PO 2- band (from 1228 to 1238cm -1 ), DNA backbone (from 970 to 966cm -1 ) and base pairing vibration of DNA (from 1717 to 1712cm -1 ) suggest distinctive changes in DNA conformation in response to irradiation. Our findings indicate that irradiation of MRSA with 470nm light induces A-DNA cleavage and that B-DNA is more resistant to damage by blue light. Blue light and UV light treatment of MRSA are complementary and distinct from the known antimicrobial effect of vancomycin. Moreover, it is known that UV-induced cleavage of DNA predominantly targets B-DNA, which is in agreement with the FTIR findings. Overall the results suggest that the combination of light and vancomycin could be a more robust approach in treating MRSA infections. Published by Elsevier B.V.

A novel XPD mutation in a compound heterozygote; the mutation in the second allele is present in three homozygous patients with mild sun sensitivity.

PubMed

Falik-Zaccai, Tzipora C; Erel-Segal, Reut; Horev, Liran; Bitterman-Deutsch, Ora; Koka, Sivan; Chaim, Sara; Keren, Zohar; Kalfon, Limor; Gross, Bella; Segal, Zvi; Orgal, Shlomi; Shoval, Yishay; Slor, Hanoch; Spivak, Graciela; Hanawalt, Philip C

2012-08-01

The XPD protein plays a pivotal role in basal transcription and in nucleotide excision repair (NER) as one of the ten known components of the transcription factor TFIIH. Mutations in XPD can result in the DNA repair-deficient diseases xeroderma pigmentosum (XP), trichothiodystrophy (TTD), cerebro-oculo-facial-skeletal syndrome, and in combined phenotypes such as XP/Cockayne syndrome and XP/TTD. We describe here an 18-year-old individual with mild sun sensitivity, no neurological abnormalities and no tumors, who carries a p.R683Q mutation in one allele, and the novel p.R616Q mutation in the other allele of the XPD gene. We also describe four patients from one family, homozygous for the identical p.R683Q mutation in XPD, who exhibit mild skin pigmentation and loss of tendon reflexes. Three homozygous patients presented with late-onset skin tumors, and two with features of premature aging and moderate cognitive decline. Cells from the compound heterozygous individual and from one of the patients homozygous for p.R683Q exhibited similar responses to UV irradiation: reduced viability and defective overall removal of UV-induced cyclobutane pyrimidine dimers, implying deficient global genomic NER. Cells from the compound heterozygous subject also failed to recover RNA synthesis after UV, indicating defective transcription-coupled NER. Mutations affecting codon 616 in XPD generally result in functionally null proteins; we hypothesize that the phenotype of the heterozygous patient results solely from expression of the p.R683Q allele. This study illustrates the importance of detailed follow up with sun sensitive individuals, to ensure appropriate prophylaxis and to understand the mechanistic basis of the implicated hereditary disease. Copyright © 2012 Wiley Periodicals, Inc.

Discrimination of corn from monocotyledonous weeds with ultraviolet (UV) induced fluorescence.

PubMed

Panneton, Bernard; Guillaume, Serge; Samson, Guy; Roger, Jean-Michel

2011-01-01

In production agriculture, savings in herbicides can be achieved if weeds can be discriminated from crop, allowing the targeting of weed control to weed-infested areas only. Previous studies demonstrated the potential of ultraviolet (UV) induced fluorescence to discriminate corn from weeds and recently, robust models have been obtained for the discrimination between monocots (including corn) and dicots. Here, we developed a new approach to achieve robust discrimination of monocot weeds from corn. To this end, four corn hybrids (Elite 60T05, Monsanto DKC 26-78, Pioneer 39Y85 (RR), and Syngenta N2555 (Bt, LL)) and four monocot weeds (Digitaria ischaemum (Schreb.) I, Echinochloa crus-galli (L.) Beauv., Panicum capillare (L.), and Setaria glauca (L.) Beauv.) were grown either in a greenhouse or in a growth cabinet and UV (327 nm) induced fluorescence spectra (400 to 755 nm) were measured under controlled or uncontrolled ambient light intensity and temperature. This resulted in three contrasting data sets suitable for testing the robustness of discrimination models. In the blue-green region (400 to 550 nm), the shape of the spectra did not contain any useful information for discrimination. Therefore, the integral of the blue-green region (415 to 455 nm) was used as a normalizing factor for the red fluorescence intensity (670 to 755 nm). The shape of the normalized red fluorescence spectra did not contribute to the discrimination and in the end, only the integral of the normalized red fluorescence intensity was left as a single discriminant variable. Applying a threshold on this variable minimizing the classification error resulted in calibration errors ranging from 14.2% to 15.8%, but this threshold varied largely between data sets. Therefore, to achieve robustness, a model calibration scheme was developed based on the collection of a calibration data set from 75 corn plants. From this set, a new threshold can be estimated as the 85% quantile on the cumulative frequency curve of the integral of the normalized red fluorescence. With this approach the classification error was nearly constant (16.0% to 18.5%), thereby indicating the potential of UV-induced fluorescence to reliably discriminate corn from monocot weeds.

Molecular and cellular analysis of the DNA repair defect in a patient in Xeroderma pigmentosum complementation group D who has the clinical features of Xeroderma pigmentosum and Cockayne syndrome

DOE Office of Scientific and Technical Information (OSTI.GOV)

Broughton, B.C.; Thompson, A.F.; Harcourt, S.A.

1995-01-01

Xeroderma pigmentosum (XP) and Cockayne syndrome (CS) are quite distinct genetic disorders that are associated with defects in excision repair of UV-induced DNA damage. A few patients have been described previously with the clinical features of both disorders. In this paper we describe an individual in this category who has unusual cellular responses to UV light. We show that his cultured fibroblasts and lymphocytes are extremely sensitive to irradiation with UV-C, despite a level of nucleotide excision repair that is 30%-40% that of normal cells. The deficiency is assigned to the XP-D complementation group, and we have identified two causativemore » mutations in the XPD gene: a gly{yields}arg change at amino acid 675 in the allele inherited from the patient`s mother and a -1 frameshift at amino acid 669 in the allele inherited from his father. These mutations are in the C-terminal 20% of the 760-amino-acid XPD protein, in a region where we have recently identified several mutations in patients with trichothiodystrophy. 44 refs., 5 figs., 2 tabs.« less

Synchrotron VUV-UV and positron lifetime spectroscopy study of vacancy-type defects in reactor neutron-irradiated MgO.nAl2O3 (n = 2)

NASA Astrophysics Data System (ADS)

Rahman, Abu Zayed Mohammad Saliqur; Cao, Xingzhong; Wang, Baoyi; Evslin, Jarah; Xu, Qiu; Atobe, Kozo

2016-12-01

We investigated neutron-irradiation-induced point defects in spinel single crystals using a synchrotron VUV-UV source and positron lifetime spectroscopy. Photoexcitation (PE) spectra near 230 nm and their corresponding photoluminescence (PL) spectra at 475 nm were attributed to F-centers. With increasing irradiation temperature and fluence, PE efficiency and PL intensity decreased dramatically. Positron lifetimes (PLT) of neutron-irradiated and non-irradiated samples were measured to identify the cation vacancies. A PLT measurement of 250 ps was obtained in a neutron-irradiated (20 K) sample which is tentatively attributed to an aluminum monovacancy. Decreasing PLT with higher irradiation indicates the formation of oxygen-vacancy complex centers.

Merkel Cell Polyomavirus Exhibits Dominant Control of the Tumor Genome and Transcriptome in Virus-Associated Merkel Cell Carcinoma.

PubMed

Starrett, Gabriel J; Marcelus, Christina; Cantalupo, Paul G; Katz, Joshua P; Cheng, Jingwei; Akagi, Keiko; Thakuria, Manisha; Rabinowits, Guilherme; Wang, Linda C; Symer, David E; Pipas, James M; Harris, Reuben S; DeCaprio, James A

2017-01-03

Merkel cell polyomavirus is the primary etiological agent of the aggressive skin cancer Merkel cell carcinoma (MCC). Recent studies have revealed that UV radiation is the primary mechanism for somatic mutagenesis in nonviral forms of MCC. Here, we analyze the whole transcriptomes and genomes of primary MCC tumors. Our study reveals that virus-associated tumors have minimally altered genomes compared to non-virus-associated tumors, which are dominated by UV-mediated mutations. Although virus-associated tumors contain relatively small mutation burdens, they exhibit a distinct mutation signature with observable transcriptionally biased kataegic events. In addition, viral integration sites overlap focal genome amplifications in virus-associated tumors, suggesting a potential mechanism for these events. Collectively, our studies indicate that Merkel cell polyomavirus is capable of hijacking cellular processes and driving tumorigenesis to the same severity as tens of thousands of somatic genome alterations. A variety of mutagenic processes that shape the evolution of tumors are critical determinants of disease outcome. Here, we sequenced the entire genome of virus-positive and virus-negative primary Merkel cell carcinomas (MCCs), revealing distinct mutation spectra and corresponding expression profiles. Our studies highlight the strong effect that Merkel cell polyomavirus has on the divergent development of viral MCC compared to the somatic alterations that typically drive nonviral tumorigenesis. A more comprehensive understanding of the distinct mutagenic processes operative in viral and nonviral MCCs has implications for the effective treatment of these tumors. Copyright © 2017 Starrett et al.

USP7 Is a Suppressor of PCNA Ubiquitination and Oxidative-Stress-Induced Mutagenesis in Human Cells.

PubMed

Kashiwaba, Shu-ichiro; Kanao, Rie; Masuda, Yuji; Kusumoto-Matsuo, Rika; Hanaoka, Fumio; Masutani, Chikahide

2015-12-15

Mono-ubiquitinated PCNA activates error-prone DNA polymerases; therefore, strict regulation of PCNA mono-ubiquitination is crucial in avoiding undesired mutagenesis. In this study, we used an in vitro assay system to identify USP7 as a deubiquitinating enzyme of mono-ubiquitinated PCNA. Suppression of USP1, a previously identified PCNA deubiquitinase, or USP7 increased UV- and H2O2-induced PCNA mono-ubiquitination in a distinct and additive manner, suggesting that USP1 and USP7 make different contributions to PCNA deubiquitination in human cells. Cell-cycle-synchronization analyses revealed that USP7 suppression increased H2O2-induced PCNA ubiquitination throughout interphase, whereas USP1 suppression specifically increased ubiquitination in S-phase cells. UV-induced mutagenesis was elevated in USP1-suppressed cells, whereas H2O2-induced mutagenesis was elevated in USP7-suppressed cells. These results suggest that USP1 suppresses UV-induced mutations produced in a manner involving DNA replication, whereas USP7 suppresses H2O2-induced mutagenesis involving cell-cycle-independent processes such as DNA repair. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Characterization of the hyperrecombination phenotype of the pol3-t mutation of Saccharomyces cerevisiae.

PubMed

Galli, Alvaro; Cervelli, Tiziana; Schiestl, Robert H

2003-05-01

The DNA polymerase delta (Pol3p/Cdc2p) allele pol3-t of Saccharomyces cerevisiae has previously been shown to increase the frequency of deletions between short repeats (several base pairs), between homologous DNA sequences separated by long inverted repeats, and between distant short repeats, increasing the frequency of genomic deletions. We found that the pol3-t mutation increased intrachromosomal recombination events between direct DNA repeats up to 36-fold and interchromosomal recombination 14-fold. The hyperrecombination phenotype of pol3-t was partially dependent on the Rad52p function but much more so on Rad1p. However, in the double-mutant rad1 Delta rad52 Delta, the pol3-t mutation still increased spontaneous intrachromosomal recombination frequencies, suggesting that a Rad1p Rad52p-independent single-strand annealing pathway is involved. UV and gamma-rays were less potent inducers of recombination in the pol3-t mutant, indicating that Pol3p is partly involved in DNA-damage-induced recombination. In contrast, while UV- and gamma-ray-induced intrachromosomal recombination was almost completely abolished in the rad52 or the rad1 rad52 mutant, there was still good induction in those mutants in the pol3-t background, indicating channeling of lesions into the above-mentioned Rad1p Rad52p-independent pathway. Finally, a heterozygous pol3-t/POL3 mutant also showed an increased frequency of deletions and MMS sensitivity at the restrictive temperature, indicating that even a heterozygous polymerase delta mutation might increase the frequency of genetic instability.

Luminescence and photoinduced absorption in ytterbium-doped optical fibres

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rybaltovsky, A A; Aleshkina, S S; Likhachev, M E

2011-12-31

Photochemical reactions induced in the glass network of an ytterbium-doped fibre core by IR laser pumping and UV irradiation have been investigated by analysing absorption and luminescence spectra. We have performed comparative studies of the photoinduced absorption and luminescence spectra of fibre preforms differing in core glass composition: Al{sub 2}O{sub 3} : SiO{sub 2}, Al{sub 2}O{sub 3} : Yb{sub 2}O{sub 3} : SiO{sub 2}, and P{sub 2}O{sub 5} : Yb{sub 2}O{sub 3} : SiO{sub 2}. The UV absorption spectra of unirradiated preform core samples show strong bands peaking at 5.1 and 6.5 eV, whose excitation plays a key role inmore » photoinduced colour centre generation in the glass network. 'Direct' UV excitation of the 5.1- and 6.5-eV absorption bands at 244 and 193 nm leads to the reduction of some of the Yb{sup 3+} ions to Yb{sup 2+}. The photodarkening of ytterbium-doped fibres by IR pumping is shown to result from oxygen hole centre generation. A phenomenological model is proposed for the IR-pumping-induced photodarkening of ytterbium-doped fibres. The model predicts that colour centre generation in the core glass network and the associated absorption in the visible range result from a cooperative effect involving simultaneous excitation of a cluster composed of several closely spaced Yb{sup 3+} ions.« less

Use of mutation spectra analysis software.

PubMed

Rogozin, I; Kondrashov, F; Glazko, G

2001-02-01

The study and comparison of mutation(al) spectra is an important problem in molecular biology, because these spectra often reflect on important features of mutations and their fixation. Such features include the interaction of DNA with various mutagens, the function of repair/replication enzymes, and properties of target proteins. It is known that mutability varies significantly along nucleotide sequences, such that mutations often concentrate at certain positions, called "hotspots," in a sequence. In this paper, we discuss in detail two approaches for mutation spectra analysis: the comparison of mutation spectra with a HG-PUBL program, (FTP: sunsite.unc.edu/pub/academic/biology/dna-mutations/hyperg) and hotspot prediction with the CLUSTERM program (www.itba.mi.cnr.it/webmutation; ftp.bionet.nsc.ru/pub/biology/dbms/clusterm.zip). Several other approaches for mutational spectra analysis, such as the analysis of a target protein structure, hotspot context revealing, multiple spectra comparisons, as well as a number of mutation databases are briefly described. Mutation spectra in the lacI gene of E. coli and the human p53 gene are used for illustration of various difficulties of such analysis. Copyright 2001 Wiley-Liss, Inc.

Holes influence the mutation spectrum of human mitochondrial DNA

NASA Astrophysics Data System (ADS)

Villagran, Martha; Miller, John

Mutations drive evolution and disease, showing highly non-random patterns of variant frequency vs. nucleotide position. We use computational DNA hole spectroscopy [M.Y. Suarez-Villagran & J.H. Miller, Sci. Rep. 5, 13571 (2015)] to reveal sites of enhanced hole probability in selected regions of human mitochondrial DNA. A hole is a mobile site of positive charge created when an electron is removed, for example by radiation or contact with a mutagenic agent. The hole spectra are quantum mechanically computed using a two-stranded tight binding model of DNA. We observe significant correlation between spectra of hole probabilities and of genetic variation frequencies from the MITOMAP database. These results suggest that hole-enhanced mutation mechanisms exert a substantial, perhaps dominant, influence on mutation patterns in DNA. One example is where a trapped hole induces a hydrogen bond shift, known as tautomerization, which then triggers a base-pair mismatch during replication. Our results deepen overall understanding of sequence specific mutation rates, encompassing both hotspots and cold spots, which drive molecular evolution.

Bioleaching of Arsenic-Rich Gold Concentrates by Bacterial Flora before and after Mutation

PubMed Central

Xie, Xuehui; Yuan, Xuewu; Liu, Na; Chen, Xiaoguang; Abdelgadir, Awad; Liu, Jianshe

2013-01-01

In order to improve the bioleaching efficiency of arsenic-rich gold concentrates, a mixed bacterial flora had been developed, and the mutation breeding method was adopted to conduct the research. The original mixed bacterial flora had been enrichedin acid mine drainage of Dexing copper mine, Jiangxi Province, China. It was induced by UV (ultraviolet), ultrasonic, and microwave, and their combination mutation. The most efficient bacterial flora after mutation was collected for further bioleaching of arsenic-rich gold concentrates. Results indicated that the bacterial flora after mutation by UV 60 s combined with ultrasonic 10 min had the best oxidation rate of ferrous, the biggest density of cells, and the most activity of total protein. During bioleaching of arsenic-rich gold concentrates, the density of the mutant bacterial cells reached to 1.13 × 108 cells/mL at 15 days, more than 10 times compared with that of the original culture. The extraction of iron reached to 95.7% after 15 days, increased by 9.9% compared with that of the original culture. The extraction of arsenic reached to 92.6% after 12 days, which was increased by 46.1%. These results suggested that optimum combined mutation could improve leaching ability of the bacterial flora more significantly. PMID:24381948

The acidic pH-induced structural changes in Pin1 as revealed by spectral methodologies

NASA Astrophysics Data System (ADS)

Wang, Jing-Zhang; Xi, Lei; Zhu, Guo-Fei; Han, Yong-Guang; Luo, Yue; Wang, Mei; Du, Lin-Fang

2012-12-01

Pin1 is closely associated with the pathogenesis of cancers and Alzheimer's disease (AD). Previously, we have shown the characteristics of the thermal denaturation of Pin1. Herein, the acid-induced denaturation of Pin1 was determined by means of fluorescence emission, synchronous fluorescence, far-UV CD, ANS fluorescence and RLS spectroscopies. The fluorescence emission spectra and the synchronous fluorescence spectra suggested the partially reversible unfolding (approximately from pH 7.0 to 4.0) and refolding (approximately from pH 4.0 to 1.0) of the structures around the chromophores in Pin1, apparently with an intermediate state at about pH 4.0-4.5. The far-UV CD spectra indicated that acidic pH (below pH 4.0) induced the structural transition from α-helix and random coils to β-sheet in Pin1. The ANS fluorescence and the RLS spectra further suggested the exposure of the hydrophobic side-chains of Pin1 and the aggregation of it especially below pH 2.3, and the aggregation possibly resulted in the formation of extra intermolecular β-sheet. The present work primarily shows that acidic pH can induce kinds of irreversible structural changes in Pin1, such as the exposure of the hydrophobic side-chains, the transition from α-helix to β-sheet and the aggregation of Pin1, and also explains why Pin1 loses most of its activity below pH 5.0. The results emphasize the important role of decreased pH in the pathogenesis of some Pin1-related diseases, and support the therapeutic approach for them by targeting acidosis and modifying the intracellular pH gradients.

UV-induced reversion of his4 frameshift mutations in rad6, rev1, and rev3 mutants of yeast.

PubMed

Lawrence, C W; O'Brien, T; Bond, J

1984-01-01

The UV-induced reversion of two his4 frameshift alleles was much reduced in rad6 mutants of Saccharomyces cerevisiae, an observation that is consistent with the hypothesis that RAD6 function is required for the induction of all types of genetic alteration in misrepair mutagenesis. The reversion of these his4 alleles, together with two others of the same type, was also reduced in rev1 and rev3 mutant strains; in these, however, the extent of the reduction varied considerably with test allele used, in a manner analogous to the results in these strains for base repair substitution test alleles. The general features of UV-induced frameshift and substitution mutagenesis therefore appear quite similar, indicating that they may depend on related processes. If this conclusion is correct, greater attention must be given to integrating models which account for the production of nucleotide additions and deletions into those concerning misrepair mutagenesis.

A UV-independent pathway to melanoma carcinogenesis in the redhair-fairskin background

PubMed Central

Mitra, Devarati; Luo, Xi; Morgan, Ann; Wang, Jin; Hoang, Mai P.; Lo, Jennifer; Guerrero, Candace R.; Lennerz, Jochen K.; Mihm, Martin C.; Wargo, Jennifer A.; Robinson, Kathleen C.; Devi, Suprabha P.; Vanover, Jillian C.; D’Orazio, John A.; McMahon, Martin; Bosenberg, Marcus W.; Haigis, Kevin M.; Haber, Daniel A.; Wang, Yinsheng; Fisher, David E.

2012-01-01

People with pale skin, red hair, freckles, and an inability to tan—the “redhair/fairskin” phenotype— are at highest risk of developing melanoma, compared to all other pigmentation types1. Genetically, this phenotype is frequently the product of inactivating polymorphisms in the Melanocortin 1 receptor (MC1R) gene. MC1R encodes a cAMP stimulating G-protein coupled receptor that controls pigment production. Minimal receptor activity, as in redhair/fairskin polymorphisms, produces red/yellow pheomelanin pigment, while increasing MC1R activity stimulates production of black/brown eumelanin2. Pheomelanin has weak UV shielding capacity relative to eumelanin and has been shown to amplify UVA-induced reactive oxygen species (ROS) 3–5. Several observations, however, complicate the assumption that melanoma risk is completely UV dependent. For example, unlike non-melanoma skin cancers, melanoma is not restricted to sun-exposed skin and UV signature mutations are infrequently oncogenic drivers6. While linkage of melanoma risk to UV exposure is beyond doubt, UV-independent events are also likely to play a significant role1,7. Here, we introduced into mice carrying an inactivating mutation in the Mc1r gene (who exhibit a phenotype analogous to redhair/fairskin humans), a conditional, melanocyte-targeted allele of the most commonly mutated melanoma oncogene, BRafV600E. We observed a high incidence of invasive melanomas without providing additional gene aberrations or UV exposure. To investigate the mechanism of UV-independent carcinogenesis, we introduced an albino allele, which ablates all pigment production on the Mc1r e/e background. Selective absence of pheomelanin synthesis was protective against melanoma development. In addition, normal Mc1re/e mouse skin was found to have significantly greater oxidative DNA and lipid damage than albino-Mc1re/e mouse skin. These data suggest that the pheomelanin pigment pathway produces UV-independent carcinogenic contributions to melanomagenesis by a mechanism of oxidative damage. While UV protection remains important, additional strategies may be required for optimal melanoma prevention. PMID:23123854

The effect of newly induced mutations on the fitness of genotypes and populations of yeast (Saccharomyces cerevisiae).

PubMed

Orthen, E; Lange, P; Wöhrmann, K

1984-12-01

This paper analyses the fate of artificially induced mutations and their importance to the fitness of populations of the yeast, Saccharomyces cerevisiae, an increasingly important model organism in population genetics. Diploid strains, treated with UV and EMS, were cultured asexually for approximately 540 generations and under conditions where the asexual growth was interrupted by a sexual phase. Growth rates of 100 randomly sampled diploid clones were estimated at the beginning and at the end of the experiment. After the induction of sporulation the growth rates of 100 randomly sampled spores were measured. UV and EMS treatment decreases the average growth rate of the clones significantly but increases the variability in comparison to the untreated control. After selection over approximately 540 generations, variability in growth rates was reduced to that of the untreated control. No increase in mean population fitness was observed. However, the results show that after selection there still exists a large amount of hidden genetic variability in the populations which is revealed when the clones are cultivated in environments other than those in which selection took place. A sexual phase increased the reduction of the induced variability.

Spectroscopic identification of rare earth elements in phosphate glass

NASA Astrophysics Data System (ADS)

Devangad, Praveen; Tamboli, Maktum; Muhammed Shameem, K. M.; Nayak, Rajesh; Patil, Ajeetkumar; Unnikrishnan, V. K.; Santhosh, C.; Kumar, G. A.

2018-01-01

In this work, rare earth-doped phosphate glasses were synthesized and characterized using three different spectroscopic techniques. The absorption spectra of the prepared praseodymium (Pr) and samarium (Sm) doped glasses, recorded by a UV-VIS-NIR spectrophotometer, show the characteristic absorption bands of these elements. To confirm this inference, laser-induced fluorescence spectra of Pr and Sm were obtained at a laser excitation of 442 nm. Their emission bands are reported here. The elemental analysis of these samples was carried out using a laser-induced breakdown spectroscopy (LIBS) system. Characteristic emission lines of Pr and Sm have been identified and reported by the recorded LIBS spectra of glass samples. Results prove that using these three complimentary spectroscopic techniques (absorption, fluorescence and LIBS), we can meaningfully characterize rare earth-doped glass samples.

Vibronic structure and coupling of higher excited electronic states in carotenoids

NASA Astrophysics Data System (ADS)

Krawczyk, Stanisław; Luchowski, Rafał

2013-03-01

Absorption spectra of all-trans carotenoids (lycopene, violaxanthin, ζ-carotene) at low temperature exhibit peculiar features in the UV range. The transition to the 11Ag+ state ('cis-band') weakens on cooling, indicating that it is induced by thermal deformations of the conjugated chain. The higher energy band has unique vibrational structure indicating the vibronic coupling of nBu with another electronic state. The electroabsorption spectra point to the electric field-induced mixing of the nBu state with the vibrational continuum of a lower-lying excited state (Fano effect). These observations widen the basis for elucidation of the vibronic coupling effects in the lower excited states.

Wavelength-dependent ultraviolet induction of cyclobutane pyrimidine dimers in the human cornea.

PubMed

Mallet, Justin D; Rochette, Patrick J

2013-08-01

Exposition to ultraviolet (UV) light is involved in the initiation and the progression of skin cancer. The genotoxicity of UV light is mainly attributed to the induction of cyclobutane pyrimidine dimers (CPDs), the most abundant DNA damage generated by all UV types (UVA, B and C). The human cornea is also exposed to the harmful UV radiations, but no UV-related neoplasm has been reported in this ocular structure. The probability that a specific DNA damage leads to a mutation and eventually to cellular transformation is influenced by its formation frequency. To shed light on the genotoxic effect of sunlight in the human eye, we have analyzed CPD induction in the cornea and the iris following irradiation of ex vivo human eyes with UVA, B or C. The extent of CPD induction was used to establish the penetrance of the different UV types in the human cornea. We show that UVB- and UVC-induced CPDs are concentrated in the corneal epithelium and do not penetrate deeply beyond this corneal layer. On the other hand, UVA wavelengths penetrate deeper and induce CPDs in the entire cornea and in the first layers of the iris. Taken together, our results are undoubtedly an important step towards better understanding the consequences of UV exposure to the human eye.

Accuracy of Td-DFT in the Ultraviolet and Circular Dichroism Spectra of Deoxyguanosine and Uridine.

PubMed

Miyahara, Tomoo; Nakatsuji, Hiroshi

2018-01-11

Accuracy of the time-dependent density functional theory (Td-DFT) was examined for the ultraviolet (UV) and circular dichroism (CD) spectra of deoxyguanosine (dG) and uridine, using 11 different DFT functionals and two different basis sets. The Td-DFT results of the UV and CD spectra were strongly dependent on the functionals used. The basis-set dependence was observed only for the CD spectral calculations. For the UV spectra, the B3LYP and PBE0 functionals gave relatively good results. For the CD spectra, the B3LYP and PBE0 with 6-311G(d,p) basis gave relatively permissible result only for dG. The results of other functionals were difficult to be used for the studies of the UV and CD spectra, though the symmetry adapted cluster-configuration interaction (SAC-CI) method reproduced well the experimental spectra of these molecules. To obtain valuable information from the theoretical calculations of the UV and CD spectra, the theoretical tool must be able to reproduce correctly both of the intensities and peak positions of the UV and CD spectra. Then, we can analyze the reasons of the changes of the intensity and/or the peak position to clarify the chemistry involved. It is difficult to recommend Td-DFT as such tools of science, at least from the examinations using dG and uridine.

Processing closely spaced lesions during Nucleotide Excision Repair triggers mutagenesis in E. coli

PubMed Central

Isogawa, Asako; Fujii, Shingo

2017-01-01

It is generally assumed that most point mutations are fixed when damage containing template DNA undergoes replication, either right at the fork or behind the fork during gap filling. Here we provide genetic evidence for a pathway, dependent on Nucleotide Excision Repair, that induces mutations when processing closely spaced lesions. This pathway, referred to as Nucleotide Excision Repair-induced Mutagenesis (NERiM), exhibits several characteristics distinct from mutations that occur within the course of replication: i) following UV irradiation, NER-induced mutations are fixed much more rapidly (t ½ ≈ 30 min) than replication dependent mutations (t ½ ≈ 80–100 min) ii) NERiM specifically requires DNA Pol IV in addition to Pol V iii) NERiM exhibits a two-hit dose-response curve that suggests processing of closely spaced lesions. A mathematical model let us define the geometry (infer the structure) of the toxic intermediate as being formed when NER incises a lesion that resides in close proximity of another lesion in the complementary strand. This critical NER intermediate requires Pol IV / Pol II for repair, it is either lethal if left unrepaired or mutation-prone when repaired. Finally, NERiM is found to operate in stationary phase cells providing an intriguing possibility for ongoing evolution in the absence of replication. PMID:28686598

Proteolytically-induced changes of secondary structural protein conformation of bovine serum albumin monitored by Fourier transform infrared (FT-IR) and UV-circular dichroism spectroscopy

NASA Astrophysics Data System (ADS)

Güler, Günnur; Vorob'ev, Mikhail M.; Vogel, Vitali; Mäntele, Werner

2016-05-01

Enzymatically-induced degradation of bovine serum albumin (BSA) by serine proteases (trypsin and α-chymotrypsin) in various concentrations was monitored by means of Fourier transform infrared (FT-IR) and ultraviolet circular dichroism (UV-CD) spectroscopy. In this study, the applicability of both spectroscopies to monitor the proteolysis process in real time has been proven, by tracking the spectral changes together with secondary structure analysis of BSA as proteolysis proceeds. On the basis of the FTIR spectra and the changes in the amide I band region, we suggest the progression of proteolysis process via conversion of α-helices (1654 cm- 1) into unordered structures and an increase in the concentration of free carboxylates (absorption of 1593 and 1402 cm- 1). For the first time, the correlation between the degree of hydrolysis and the concentration of carboxylic groups measured by FTIR spectroscopy was revealed as well. The far UV-CD spectra together with their secondary structure analysis suggest that the α-helical content decreases concomitant with an increase in the unordered structure. Both spectroscopic techniques also demonstrate that there are similar but less spectral changes of BSA for the trypsin attack than for α-chymotrypsin although the substrate/enzyme ratio is taken the same.

UV-induced Melanin Chemiexcitation: A New Mode of Melanoma Pathogenesis.

PubMed

Brash, Douglas E

2016-06-01

Mutations in sunlight-induced melanoma arise from cyclobutane pyrimidine dimers (CPDs), DNA photoproducts usually created picoseconds after an ultraviolet (UV) photon is absorbed at thymine or cytosine. Surprisingly, we found that, in melanocytes, CPDs were generated for hours after UVA or UVB exposure. These "dark CPDs" constituted the majority of CPDs in cultured human and murine melanocytes and in mouse skin, and they were most prominent in skin containing pheomelanin, the melanin responsible for blonde and red hair. The mechanism was also a surprise. Dark cyclobutane pyrimidine dimers (CPDs) arise when ultraviolet (UV)-induced superoxide and nitric oxide combine to form peroxynitrite, one of the few biological molecules capable of exciting an electron. This process, termed "chemiexcitation," is the source of bioluminescence in lower organisms. Excitation occurred in fragments of melanin, creating a quantum triplet state that had the energy of a UV photon but which induced CPDs by radiationless energy transfer to DNA. UVA and peroxynitrite also solubilized melanin and permeabilized the nuclear membrane, allowing melanin to enter. Melanin is evidently carcinogenic as well as protective. Chemiexcitation may also trigger pathogenesis in internal tissues because the same chemistry should arise wherever superoxide and nitric oxide arise near cells that contain melanin. © The Author(s) 2016.

Evidence that a burst of DNA depurination in SENCAR mouse skin induces error-prone repair and forms mutations in the H-ras gene.

PubMed

Chakravarti, D; Mailander, P C; Li, K M; Higginbotham, S; Zhang, H L; Gross, M L; Meza, J L; Cavalieri, E L; Rogan, E G

2001-11-29

Treatment of SENCAR mouse skin with dibenzo[a,l]pyrene results in abundant formation of abasic sites that undergo error-prone excision repair, forming oncogenic H-ras mutations in the early preneoplastic period. To examine whether the abundance of abasic sites causes repair infidelity, we treated SENCAR mouse skin with estradiol-3,4-quinone (E(2)-3,4-Q) and determined adduct levels 1 h after treatment, as well as mutation spectra in the H-ras gene between 6 h and 3 days after treatment. E(2)-3,4-Q formed predominantly (> or =99%) the rapidly-depurinating 4-hydroxy estradiol (4-OHE(2))-1-N3Ade adduct and the slower-depurinating 4-OHE(2)-1-N7Gua adduct. Between 6 h and 3 days, E(2)-3,4-Q induced abundant A to G mutations in H-ras DNA, frequently in the context of a 3'-G residue. Using a T.G-DNA glycosylase (TDG)-PCR assay, we determined that the early A to G mutations (6 and 12 h) were in the form of G.T heteroduplexes, suggesting misrepair at A-specific depurination sites. Since G-specific mutations were infrequent in the spectra, it appears that the slow rate of depurination of the N7Gua adducts during active repair may not generate a threshold level of G-specific abasic sites to affect repair fidelity. These results also suggest that E(2)-3,4-Q, a suspected endogenous carcinogen, is a genotoxic compound and could cause mutations.

The Aspergillus nidulans npkA gene encodes a Cdc2-related kinase that genetically interacts with the UvsBATR kinase.

PubMed Central

Fagundes, Marcia R V Z Kress; Lima, Joel Fernandes; Savoldi, Marcela; Malavazi, Iran; Larson, Roy E; Goldman, Maria H S; Goldman, Gustavo H

2004-01-01

The DNA damage response is a protective mechanism that ensures the maintenance of genomic integrity. We have used Aspergillus nidulans as a model system to characterize the DNA damage response caused by the antitopoisomerase I drug, camptothecin. We report the molecular characterization of a p34Cdc2-related gene, npkA, from A. nidulans. The npkA gene is transcriptionally induced by camptothecin and other DNA-damaging agents, and its induction in the presence of camptothecin is dependent on the uvsBATR gene. There were no growth defects, changes in developmental patterns, increased sensitivity to DNA-damaging agents, or effects on septation or growth rate in the A. nidulans npkA deletion strain. However, the DeltanpkA mutation can partially suppress HU sensitivity caused by the DeltauvsBATR and uvsD153ATRIP checkpoint mutations. We demonstrated that the A. nidulans uvsBATR gene is involved in DNA replication and the intra-S-phase checkpoints and that the DeltanpkA mutation can suppress its intra-S-phase checkpoint deficiency. There is a defect in both the intra-S-phase and DNA replication checkpoints due to the npkA inactivation when DNA replication is slowed at 6 mm HU. Our results suggest that the npkA gene plays a role in cell cycle progression during S-phase as well as in a DNA damage signal transduction pathway in A. nidulans. PMID:15342504

UV-tunable laser induced phototransformations of matrix isolated anethole.

PubMed

Krupa, Justyna; Wierzejewska, Maria; Nunes, Cláudio M; Fausto, Rui

2014-03-14

A matrix isolation study of the infrared spectra and structure of anethole (1-methoxy-4-(1-propenyl)benzene) has been carried out, showing the presence of two E conformers (AE1, AE2) of the molecule in the as-deposited matrices. Irradiation using ultraviolet-tunable laser light at 308-307 nm induced conformationally selective phototransformations of these forms into two less stable Z conformers (AZ1, AZ2). The back reactions were also detected upon irradiation at 301 nm. On the whole, the obtained results allow for full assignment of the infrared spectra of all the four experimentally observed anethole isomers and showed that the narrowband UV-induced E-Z photoisomerization is an efficient and selective way to interconvert the two isomers of anethole into each other, with conformational discrimination. Photolysis of anethole was observed as well, with initial methoxyl O-C bond cleavage and formation of CH3 and p-propenylphenoxy (AR) radicals, followed by radical recombination to form 2-methyl-4-propenyl-2,4-cyclohexadienone, which subsequently undergoes ring-opening generating several conformers of long-chain conjugated ketenes. Interpretation of the experimental observations was supported by density functional theory (B3LYP and B2PLYD) calculations.

The effect of DNA replication on mutation of the Saccharomyces cerevisiae CDC8 gene.

PubMed

Zaborowska, D; Zuk, J

1990-04-01

Incubation in YPD medium under permissive conditions when DNA replication is going on, strongly stimulates the induction of cdc+ colonies of UV-irradiated cells of yeast strains HB23 (cdc8-1/cdc8-3), HB26 (cdc8-3/cdc8-3) and HB7 (cdc8-1/cdc8-1). Inhibition of DNA replication by hydroxyurea, araCMP, cycloheximide or caffeine or else by incubation in phosphate buffer pH 7.0, abolishes this stimulation. Thus the replication of DNA is strongly correlated with the high induction of cdc+ colonies by UV irradiation. It is postulated that these UV-induced cdc+ colonies arise as the result infidelity in DNA replication.

A nuclear mutation defective in mitochondrial recombination in yeast.

PubMed

Ling, F; Makishima, F; Morishima, N; Shibata, T

1995-08-15

Homologous recombination (crossing over and gene conversion) is generally essential for heritage and DNA repair, and occasionally causes DNA aberrations, in nuclei of eukaryotes. However, little is known about the roles of homologous recombination in the inheritance and stability of mitochondrial DNA which is continuously damaged by reactive oxygen species, by-products of respiration. Here, we report the first example of a nuclear recessive mutation which suggests an essential role for homologous recombination in the stable inheritance of mitochondrial DNA. For the detection of this class of mutants, we devised a novel procedure, 'mitochondrial crossing in haploid', which has enabled us to examine many mutant clones. Using this procedure, we examined mutants of Saccharomyces cerevisiae that showed an elevated UV induction of respiration-deficient mutations. We obtained a mutant that was defective in both the omega-intron homing and Endo.SceI-induced homologous gene conversion. We found that the mutant cells are temperature sensitive in the maintenance of mitochondrial DNA. A tetrad analysis indicated that elevated UV induction of respiration-deficient mutations, recombination deficiency and temperature sensitivity are all caused by a single nuclear mutation (mhr1) on chromosome XII. The pleiotropic characteristics of the mutant suggest an essential role for the MHR1 gene in DNA repair, recombination and the maintenance of DNA in mitochondria.

Problems in abundance determination from UV spectra of hot supergiants

NASA Astrophysics Data System (ADS)

Deković, M. Sarta; Kotnik-Karuza, D.; Jurkić, T.; Dominis Prester, D.

2010-03-01

We present measurements of equivalent widths of the UV, presumably photospheric lines: C III 1247 Å, N III 1748 Å, N III 1752 Å, N IV 1718 Å and He II 1640 Å in high-resolution IUE spectra of 24 galactic OB supergiants. Equivalent widths measured from the observed spectra have been compared with their counterparts in the Tlusty NLTE synthetic spectra. We discuss possibilities of static plan-parallel model to reproduce observed UV spectra of hot massive stars and possible reasons why observations differ from the model so much.

Modification of mutagenesis initiated by ultraviolet light through posttreatment of bacteria with basic dyes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Witkin, E M

1961-12-01

Post treatment with basic dyes, in concentrations that retard cell division, was found to influence the tnduction of mutations to prototrophy by UV light in a tyrosine-requirtng strain of E.Coli. Pyronin, which is unique among the dyes in tts selective affinity for RNA, was found to duplicate the effects of chloramphenicol or amino acfd deprtvatfon in causfng the rapid and irreversible loss of potential prototrophs (mutation frequency decline, or MFD). Acriflavtne, methyl green. crystal violet, methylene blue, and toluidine blue, all of which are known to combine with DNA, delay or retard the occurrence of MFD under conditions of aminomore » acid deprivation. When acriflavine is removed from its combination with cellular components by the addition of an excess of sodium deoxyrtbonucleate, MFD begins promptly. The same basic dyes that delay MFD were also found to interfere with the fixation of mutations (MF) in an amino acid- enriched medium, and to cause marked enhancement of the mutagenic potency of low doses of UV light. While showing no independent mutagenic activity for unirradiated bacteria, all the dyes except pyronin increased the yield of induced mutations signtficantly when added to the enriched medium upon which trradiated bacteria were incubated.These results were interpreted as evidence that UV light initiates mutagenesis by producing unstable changas directly in genic DNA. MFD is interpreted as a repair process, blocked by the machinery of RNA and protein synthesis and by the presence of certain basic dyes.« less

UV-B Radiation Contributes to Amphibian Population Declines

NASA Astrophysics Data System (ADS)

Blaustein, Andrew

2007-05-01

UV-B (280-315 nm) radiation is the most significant biologically damaging radiation at the terrestrial surface. At the organismal level, UV-B radiation can slow growth rates, cause immune dysfunction and result in sublethal damage. UV-B radiation can lead to mutations and cell death. Over evolutionary time, UV radiation has been an important stressor on living organisms. Natural events, including impacts from comets and asteroids, volcanic activity, supernova explosions and solar flares, can cause large-scale ozone depletion with accompanying increases in UV radiation. However, these natural events are transient. Moreover, the amount of ozone damage due to natural events depends upon a number of variables, including the magnitude of the event. This is different from modern-day human-induced production of chlorofluorocarbons (CFCs) and other chemicals that deplete stratospheric ozone continuously, resulting in long-term increases in UV-B radiation at the surface of the earth. We will briefly review the effects of UV-B exposure in one group of aquatic organisms_amphibians. UV-B has been implicated as a possible factor contributing to global declines and range reductions in amphibian populations.

3H-1,2-dithiole-3-thione protects retinal pigment epithelium cells against Ultra-violet radiation via activation of Akt-mTORC1-dependent Nrf2-HO-1 signaling.

PubMed

Li, Ke-Ran; Yang, Su-Qing; Gong, Yi-Qing; Yang, Hong; Li, Xiu-Miao; Zhao, Yu-Xia; Yao, Jin; Jiang, Qin; Cao, Cong

2016-05-06

Excessive UV radiation and reactive oxygen species (ROS) cause retinal pigment epithelium (RPE) cell injuries. Nrf2 regulates transcriptional activation of many anti-oxidant genes. Here, we tested the potential role of 3H-1,2-dithiole-3-thione (D3T) against UV or ROS damages in cultured RPE cells (both primary cells and ARPE-19 line). We showed that D3T significantly inhibited UV-/H2O2-induced RPE cell death and apoptosis. UV-stimulated ROS production was dramatically inhibited by D3T pretreatment. D3T induced Nrf2 phosphorylation in cultured RPE cells, causing Nrf2 disassociation with KEAP1 and its subsequent nuclear accumulation. This led to expression of antioxidant response elements (ARE)-dependent gene heme oxygenase-1 (HO-1). Nrf2-HO-1 activation was required for D3T-mediated cytoprotective effect. Nrf2 shRNA knockdown or S40T dominant negative mutation as well as the HO-1 inhibitor Zinc protoporphyrin (ZnPP) largely inhibited D3T's RPE cytoprotective effects against UV radiation. Yet, exogenous overexpression Nrf2 enhanced D3T's activity in RPE cells. Further studies showed that D3T activated Akt/mTORC1 in cultured RPE cells. Akt-mTORC1 inhibitors, or Akt1 knockdown by shRNA, not only inhibited D3T-induced Nrf2-HO-1 activation, but also abolished the RPE cytoprotective effects. In vivo, D3T intravitreal injection protected from light-induced retinal dysfunctions in mice. Thus, D3T protects RPE cells from UV-induced damages via activation of Akt-mTORC1-Nrf2-HO-1 signaling axis.

Hydrogen atom transfer reactions in thiophenol: photogeneration of two new thione isomers.

PubMed

Reva, Igor; Nowak, Maciej J; Lapinski, Leszek; Fausto, Rui

2015-02-21

Photoisomerization reactions of monomeric thiophenol have been investigated for the compound isolated in low-temperature argon matrices. The initial thiophenol population consists exclusively of the thermodynamically most stable thiol form. Phototransformations were induced by irradiation of the matrices with narrowband tunable UV light. Irradiation at λ > 290 nm did not induce any changes in isolated thiophenol molecules. Upon irradiation at 290-285 nm, the initial thiol form of thiophenol converted into its thione isomer, cyclohexa-2,4-diene-1-thione. This conversion occurs by transfer of an H atom from the SH group to a carbon atom at the ortho position of the ring. Subsequent irradiation at longer wavelengths (300-427 nm) demonstrated that this UV-induced hydrogen-atom transfer is photoreversible. Moreover, upon irradiation at 400-425 nm, the cyclohexa-2,4-diene-1-thione product converts, by transfer of a hydrogen atom from the ortho to para position, into another thione isomer, cyclohexa-2,5-diene-1-thione. The latter thione isomer is also photoreactive and is consumed if irradiated at λ < 332 nm. The obtained results clearly show that H-atom-transfer isomerization reactions dominate the unimolecular photochemistry of thiophenol confined in a solid argon matrix. A set of low-intensity infrared bands, observed in the spectra of UV irradiated thiophenol, indicates the presence of a phenylthiyl radical with an H- atom detached from the SH group. Alongside the H-atom-transfer and H-atom-detachment processes, the ring-opening photoreaction occurred in cyclohexa-2,4-diene-1-thione by the cleavage of the C-C bond at the alpha position with respect to the thiocarbonyl C[double bond, length as m-dash]S group. The resulting open-ring conjugated thioketene adopts several isomeric forms, differing by orientations around single and double bonds. The species photogenerated upon UV irradiation of thiophenol were identified by comparison of their experimental infrared spectra with the spectra theoretically calculated for the candidate structures at the B3LYP/aug-cc-pVTZ level.

Analysis of mutational spectra by denaturant capillary electrophoresis

PubMed Central

Ekstrøm, Per O.; Khrapko, Konstantin; Li-Sucholeiki, Xiao-Cheng; Hunter, Ian W.; Thilly, William G.

2009-01-01

Numbers and kinds of point mutant within DNA from cells, tissues and human population may be discovered for nearly any 75–250bp DNA sequence. High fidelity DNA amplification incorporating a thermally stable DNA “clamp” is followed by separation by denaturing capillary electrophoresis (DCE). DCE allows for peak collection and verification sequencing. DCE in a mode of cycling temperature, e.g.+/− 5°C, CyDCE, permits high resolution of mutant sequences using computer defined analytes without preliminary optimization experiments. DNA sequencers have been modified to permit higher throughput CyDCE and a massively parallel,~25,000 capillary system, has been designed for pangenomic scans in large human populations. DCE has been used to define quantitative point mutational spectra for study a wide variety of genetic phenomena: errors of DNA polymerases, mutations induced in human cells by chemicals and irradiation, testing of human gene-common disease associations and the discovery of origins of point mutations in human development and carcinogenesis. PMID:18600220

Isolation of new white collar mutants of Neurospora crassa and studies on their behavior in the blue light-induced formation of protoperithecia.

PubMed Central

Degli-Innocenti, F; Russo, V E

1984-01-01

White collar (wc) mutants of Neurospora crassa are thought to be regulatory mutants blocked in the photoinduction of carotenogenesis. Eight new wc mutants have been isolated after UV mutagenesis; their morphology and linear growth rate are not altered, although blue light-induced carotenogenesis is completely blocked. All of the wc mutations fall into two complementation groups corresponding to the already-known wc-1 and wc-2 loci. It is shown that the wc mutations impair another blue light effect, the photoinduction of protoperithecia formation, as well as the low constitutive production of protoperithecia in the dark. These effects are not due to the lack of carotenoids since the albino mutants show a normal sexual development. The pleiotropic effects of the mutations in the wc genes indicate that they play a key role in the mechanisms of regulation of the blue light-induced responses of N. crassa. PMID:6235211

Shared Oncogenic Pathways Implicated in Both Virus-Positive and UV-Induced Merkel Cell Carcinomas.

PubMed

González-Vela, María Del Carmen; Curiel-Olmo, Soraya; Derdak, Sophia; Beltran, Sergi; Santibañez, Miguel; Martínez, Nerea; Castillo-Trujillo, Alfredo; Gut, Martha; Sánchez-Pacheco, Roxana; Almaraz, Carmen; Cereceda, Laura; Llombart, Beatriz; Agraz-Doblas, Antonio; Revert-Arce, José; López Guerrero, José Antonio; Mollejo, Manuela; Marrón, Pablo Isidro; Ortiz-Romero, Pablo; Fernandez-Cuesta, Lynnette; Varela, Ignacio; Gut, Ivo; Cerroni, Lorenzo; Piris, Miguel Ángel; Vaqué, José Pedro

2017-01-01

Merkel cell carcinoma (MCC) is a highly malignant neuroendocrine tumor of the skin whose molecular pathogenesis is not completely understood, despite the role that Merkel cell polyomavirus can play in 55-90% of cases. To study potential mechanisms driving this disease in clinically characterized cases, we searched for somatic mutations using whole-exome sequencing, and extrapolated our findings to study functional biomarkers reporting on the activity of the mutated pathways. Confirming previous results, Merkel cell polyomavirus-negative tumors had higher mutational loads with UV signatures and more frequent mutations in TP53 and RB compared with their Merkel cell polyomavirus-positive counterparts. Despite important genetic differences, the two Merkel cell carcinoma etiologies both exhibited nuclear accumulation of oncogenic transcription factors such as NFAT or nuclear factor of activated T cells (NFAT), P-CREB, and P-STAT3, indicating commonly deregulated pathogenic mechanisms with the potential to serve as targets for therapy. A multivariable analysis identified phosphorylated CRE-binding protein as an independent survival factor with respect to clinical variables and Merkel cell polyomavirus status in our cohort of Merkel cell carcinoma patients. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

The impact of solar UV radiation on the early biosphere

NASA Astrophysics Data System (ADS)

Horneck, G.

2007-08-01

Stratospheric ozone, photochemically produced from atmospheric oxygen, is a protective filter of the Earth's atmosphere by absorbing most of the biologically harmful UV radiation of our sun in the UV-C (190-280 nm) and short wavelength-region of the UV-B (280-315 nm). Numerous lines of isotopic and geologic evidence suggest that the Archean atmosphere was essentially anoxic. As a result the column abundance of ozone would have been insufficient to affect the surface UV radiation environment. Thus, as well as UV-B radiation, UV-C radiation would have penetrated to the Earth's surface with its associated biological consequences. The history of this ultraviolet stress for the early Earth has been determined from theoretical data and data obtained in Earth orbit on the inactivation of Bacillus subtilis spores under a simulated ozone layer of different thicknesses. Although the UV-C and UV-B regions contribute only 2 % of the entire solar extraterrestrial irradiance, photobiological experiments in space have demonstrated a high mutagenicity and lethality of this UV range to living organisms. The reason for these severe effects of extraterrestrial solar UV radiation - compared to conditions on present-day Earth - lies in the absorption characteristics of the DNA, which is the decisive target for inactivation and mutation induction at this UV range. Being a strong mutagen, UV-radiation is considered as a powerful promoter of biological evolution on the one hand, one the other hand, it may have deleterious consequences to individual cells and organisms, e.g. by causing inactivation, mutations or cancer induction. In response to potential harmful effects of environmental UV radiation, life on Earth has developed several strategies of survival, either avoiding exposure to UV radiation or restoring UV damage. Mechanisms of avoidance of exposure to UV radiation include (i) moving away from the UV radiation into shadowed areas, which requires the development of UV radiation sensing mechanisms; (ii) application of external shielding, such as covering by mud, sand or rock material; (iii) development of intrinsic UV screening pigments, such as tanning, inductive flavonoid production of plants, intracellular mycosporin production in cyanobacteria, (iv) accumulation of antioxidants and quenching substances. However, if UV damage has been induced - in spite of all avoidance efforts, organisms may restore their functionality by numerous repair processes. Repair pathways of a rich diversity and functional universality include (i) direct repair with the reversal of photochemical abnormalities, e.g. in the DNA; (ii) recombination repair removing the UV-induced abnormality by homologous recombination; and (iii) excision repair, where the section of the DNA strand containing the abnormality is removed and a repair patch is synthesized using the intact strand as a template. In addition to efficient repair systems for radiation-induced DNA injury, life has developed a variety of defense mechanisms, such as the increase in the production of stress proteins and the activation of the immune defence system. Some of these capacities have certainly already been evolved in the early biosphere, when it was exposed to the extended UV-spectrum of the sun. Only since the early Proterozoic, due to a rapid rise in the atmospheric oxygen concentration and consequently a photochemical built up of the stratospheric ozone layer, a more moderate UV radiation climate prevailed with wavelengths shorter than 295 nm being effectively cut off.

Thermally and vibrationally induced conformational isomerizations, infrared spectra, and photochemistry of gallic acid in low-temperature matrices

NASA Astrophysics Data System (ADS)

Justino, Licínia L. G.; Reva, Igor; Fausto, Rui

2016-07-01

Near-infrared (near-IR) narrowband selective vibrational excitation and annealing of gallic acid (3,4,5-trihydroxybenzoic acid) isolated in cryogenic matrices were used to induce interconversions between its most stable conformers. The isomerizations were probed by infrared spectroscopy. An extensive set of quantum chemical calculations, carried out at the DFT(B3LYP)/6-311++G(d,p) level of approximation, was used to undertake a detailed analysis of the ground state potential energy surface of the molecule. This investigation of the molecule conformational space allowed extracting mechanistic insights into the observed annealing- or near-IR-induced isomerization processes. The infrared spectra of the two most stable conformers of gallic acid in N2, Xe, and Ar matrices were fully assigned. Finally, the UV-induced photochemistry of the matrix isolated compound was investigated.

Variability of pre-vitamin D3 effectiveness of UV appliances for skin tanning.

PubMed

Sayre, Robert M; Dowdy, John C; Shepherd, James G

2010-07-01

While there is limited documentation that certain indoor tanning lamps effectively produce vitamin D, the diversity of such devices has not been extensively surveyed. This study compares the spectral effectiveness of a variety of tanning units, and solar spectra, for ultraviolet (UV) photosynthesis of pre-vitamin D3 (preD3) and UV induced erythema. Well-established techniques exist for the calculation of spectral effectiveness for photobiological responses that have defined action spectra. Using spectroradiometric data from sunlamp measurements, and standard solar reference spectra, we computed effective irradiances using the CIE action spectrum for the production of preD3 in human skin and the ISO/CIE human erythema reference action spectrum. We found, as with sunlight at different times or latitude, the preD3 and erythemal effectiveness of sunlamps varied as a function of the UV-B proportion of the spectrum. Ratios of sunlamp preD3 to erythemal effectiveness ranged from approximately 0.5 to nearly 2.0, similar to ratios for sunlight. Optimal risk to benefit conditions for preD3 from solar UV exposure occurs under high solar altitude, low zenith angle, midday midsummer sunlight. Analogous optimal preD3 exposure conditions are provided by low to intermediate pressure sunlamps with greater UV-B spectral overlap with the preD3 action spectrum. Similar to low altitude or high latitude sunlight, high pressure tanning units, filtered for negligible UV-B emissions, have insignificant vitamin D benefit. We conclude that while vitamin D can be made by both UVB exposure from indoor tanning units and by exposure UVB from sunlight, the effect is also comparably variable. Unlike sunlight, indoor tanning offers privacy and environmental conditions for practical full body exposure, lowering the requisite exposure per skin surface area, and device timers limit the potential of overexposure. Guidance for optimal use of tanning sources for vitamin D benefit is needed. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Raman spectroscopic analysis of the responds of desert cyanobacterium Nostoc sp under UV-B radiation

NASA Astrophysics Data System (ADS)

Wang, Gaohong; Hao, Zongjie; Hu, Chunxiang; Liu, Yongding

Cyanobacteria are renowned for tolerating extremes of desiccation, UV radiation, freezethaw cycles, hypersalinity and oligotrophy, which make them as candidate par excellence for terraforming in extraterrestrial planet. Recently Raman spectrum was applied to study the biochemical information changes in different field of life science. In this study, we investigated the respond of desert cyanobactreium Nostoc sp under UV-B radiation via FT-Raman spectra. It was found that the spectral biomarkers of protectant molecular of UV radiation such as β-carotene and scytonemin were induced by UV-B radiation, but Chlorophyll a content was decreased, and also the photosynthesis activity was inhibited significantly. After light adaptation without UV-B radiation, the Chlorophyll a content and photosynthesis activity returned to high level, butβ-carotene and scytonemin content remained in the cells. Those results indicated that desert Cyanobacteria have good adaptation ability for UV-B radiation and synthesis of protectant molecular may be an effective strategy for its adaptation in evolution.

Determining the Location of DNA Modification and Mutation Caused by UVB Light in Skin Cancer

DTIC Science & Technology

2013-09-01

we obtain cleavage patterns consistent with the administered UV dosage and that sequencing libraries generated for both yeast and human cells show...understanding the mutations they cause. 15. SUBJECT TERMS UV DNA modification, HeLa cells, Skin Cancer 16. SECURITY CLASSIFICATION OF: 17...of mutations that are caused by UV light in cells and correlate them to modification frequencies. Understanding the initial chemical changes

The UV-VIS optical environment of the shuttle

NASA Technical Reports Server (NTRS)

Torr, M. R.

1985-01-01

During the Spacelab 1 shuttle mission, spectroscopic measurements were made of the atmospheric emissions over a broad wavelength range extending from the extreme ultraviolet to the near infrared. Those measurements were made under a variety of vehicle attitude and sunlight conditions. Superimposed on such spectra would be any features associated with the induced vehicle environment and its interaction with solar photons and the ambient neutral atmosphere and plasma. Various anomalies and unexpected features in the spectra from the perspective of possible shuttle-induced origins are discussed. The data indicate a dramatic cleanup of the vehicle environment over the course of the 10-day mission, a strong non-atmospheric red continuum underlying the spectra at night and at large angles to the velocity vector, and a variety of molecular band distributions which are not explained by the present understanding of the atmosphere.

Shedding light on proteins, nucleic acids, cells, humans and fish

NASA Technical Reports Server (NTRS)

Setlow, Richard B.

2002-01-01

I was trained as a physicist in graduate school. Hence, when I decided to go into the field of biophysics, it was natural that I concentrated on the effects of light on relatively simple biological systems, such as proteins. The wavelengths absorbed by the amino acid subunits of proteins are in the ultraviolet (UV). The wavelengths that affect the biological activities, the action spectra, also are in the UV, but are not necessarily parallel to the absorption spectra. Understanding these differences led me to investigate the action spectra for affecting nucleic acids, and the effects of UV on viruses and cells. The latter studies led me to the discovery of the important molecular nature of the damages affecting DNA (cyclobutane pyrimidine dimers) and to the discovery of nucleotide excision repair. Individuals with the genetic disease xeroderma pigmentosum (XP) are extraordinarily sensitive to sunlight-induced skin cancer. The finding, by James Cleaver, that their skin cells were defective in DNA repair strongly suggested that DNA damage was a key step in carcinogenesis. Such information was important for estimating the wavelengths in sunlight responsible for human skin cancer and for predicting the effects of ozone depletion on the incidence of non-melanoma skin cancer. It took experiments with backcross hybrid fish to call attention to the probable role of the longer UV wavelengths not absorbed by DNA in the induction of melanoma. These reflections trace the biophysicist's path from molecules to melanoma.

Persistence of Repair Proteins at Unrepaired DNA Damage Distinguishes Diseases with ERCC2 (XPD) Mutations: Cancer-Prone Xeroderma Pigmentosum vs. Non-Cancer-Prone Trichothiodystrophy

PubMed Central

Boyle, Jennifer; Ueda, Takahiro; Oh, Kyu-Seon; Imoto, Kyoko; Tamura, Deborah; Jagdeo, Jared; Khan, Sikandar G.; Nadem, Carine; DiGiovanna, John J.; Kraemer, Kenneth H.

2012-01-01

Patients with xeroderma pigmentosum (XP) have a 1,000-fold increase in ultraviolet (UV)-induced skin cancers while trichothiodystrophy (TTD) patients, despite mutations in the same genes, ERCC2 (XPD) or ERCC3 (XPB), are cancer-free. Unlike XP cells, TTD cells have a nearly normal rate of removal of UV-induced 6-4 photoproducts (6-4PP) in their DNA and low levels of the basal transcription factor, TFIIH. We examined seven XP, TTD, and XP/TTD complex patients and identified mutations in the XPD gene. We discovered large differences in nucleotide excision repair (NER) protein recruitment to sites of localized UV damage in TTD cells compared to XP or normal cells. XPC protein was rapidly localized in all cells. XPC was redistributed in TTD, and normal cells by 3 hr postirradiation, but remained localized in XP cells at 24-hr postirradiation. In XP cells recruitment of other NER proteins (XPB, XPD, XPG, XPA, and XPF) was also delayed and persisted at 24 hr (p < 0.001). In TTD cells with defects in the XPD, XPB, or GTF2H5 (TTDA) genes, in contrast, recruitment of these NER proteins was reduced compared to normals at early time points (p < 0.001) and remained low at 24 hr postirradiation. These data indicate that in XP persistence of NER proteins at sites of unrepaired DNA damage is associated with greatly increased skin cancer risk possibly by blockage of translesion DNA synthesis. In contrast, in TTD, low levels of unstable TFIIH proteins do not accumulate at sites of unrepaired photoproducts and may permit normal translesion DNA synthesis without increased skin cancer. PMID:18470933

Rapid profiling of laser-induced photochemistry in single microdroplets using mass spectrometry.

PubMed

Tracey, Phillip J; Vaughn, Bartholomew S; Roberts, Brendon J; Poad, Berwyck L J; Trevitt, Adam J

2014-03-18

Rapid assessment of laser-induced photochemistry in single microdroplets is afforded by on-demand microdroplet generation coupled to a commercial ion-trap mass spectrometer. Single microdroplets (diameter ∼50 μm, 65 pL) fall on a steel needle held at +2 kV where they subsequently form a spray that is directed toward the inlet of an ion-trap mass spectrometer. It is demonstrated that single microdroplet mass spectra are recordable, one at a time, for methanol droplets containing 100 μM 4-iodoaniline. Extending on this, to probe laser-initiated photochemistry in single picoliter volumes, a UV laser pulse is timed to intercept the droplet before hitting the needle. Comparison of laser-on and laser-off mass spectra reveals the laser-initiated photochemical products. We demonstrate the technique by following UV laser initiated chemistry in methanol droplets containing 4-iodoaniline and 3-(iodomethyl)-N,N,N-trimethylbenzenamine and reveal numerous products within a few hundred single droplet experiments over several minutes. This technique allows for rapid detection of laser-initiated photochemistry in single picoliter volumes.

DNA polymerase ζ cooperates with polymerases κ and ι in translesion DNA synthesis across pyrimidine photodimers in cells from XPV patients

PubMed Central

Ziv, Omer; Geacintov, Nicholas; Nakajima, Satoshi; Yasui, Akira; Livneh, Zvi

2009-01-01

Human cells tolerate UV-induced cyclobutane pyrimidine dimers (CPD) by translesion DNA synthesis (TLS), carried out by DNA polymerase η, the POLH gene product. A deficiency in DNA polymerase η due to germ-line mutations in POLH causes the hereditary disease xeroderma pigmentosum variant (XPV), which is characterized by sunlight sensitivity and extreme predisposition to sunlight-induced skin cancer. XPV cells are UV hypermutable due to the activity of mutagenic TLS across CPD, which explains the cancer predisposition of the patients. However, the identity of the backup polymerase that carries out this mutagenic TLS was unclear. Here, we show that DNA polymerase ζ cooperates with DNA polymerases κ and ι to carry out error-prone TLS across a TT CPD. Moreover, DNA polymerases ζ and κ, but not ι, protect XPV cells against UV cytotoxicity, independently of nucleotide excision repair. This presents an extreme example of benefit-risk balance in the activity of TLS polymerases, which provide protection against UV cytotoxicity at the cost of increased mutagenic load. PMID:19564618

DNA polymerase zeta cooperates with polymerases kappa and iota in translesion DNA synthesis across pyrimidine photodimers in cells from XPV patients.

PubMed

Ziv, Omer; Geacintov, Nicholas; Nakajima, Satoshi; Yasui, Akira; Livneh, Zvi

2009-07-14

Human cells tolerate UV-induced cyclobutane pyrimidine dimers (CPD) by translesion DNA synthesis (TLS), carried out by DNA polymerase eta, the POLH gene product. A deficiency in DNA polymerase eta due to germ-line mutations in POLH causes the hereditary disease xeroderma pigmentosum variant (XPV), which is characterized by sunlight sensitivity and extreme predisposition to sunlight-induced skin cancer. XPV cells are UV hypermutable due to the activity of mutagenic TLS across CPD, which explains the cancer predisposition of the patients. However, the identity of the backup polymerase that carries out this mutagenic TLS was unclear. Here, we show that DNA polymerase zeta cooperates with DNA polymerases kappa and iota to carry out error-prone TLS across a TT CPD. Moreover, DNA polymerases zeta and kappa, but not iota, protect XPV cells against UV cytotoxicity, independently of nucleotide excision repair. This presents an extreme example of benefit-risk balance in the activity of TLS polymerases, which provide protection against UV cytotoxicity at the cost of increased mutagenic load.

Mutation induction in haploid yeast after split-dose radiation-exposure. I. Fractionated UV-irradiation.

PubMed

Schenk, K; Zölzer, F; Kiefer, J

1989-01-01

Mutation induction was investigated in wild-type haploid yeast Saccharomyces cerevisiae after split-dose UV-irradiation. Cells were exposed to fractionated 254 nm-UV-doses separated by intervals from 0 to 6 h with incubation either on non-nutrient or nutrient agar between. The test parameter was resistance to canavanine. If modifications of sensitivity due to incubation are appropriately taken into account there is no change of mutation frequency.

Oxidative stress-induced protein damage inhibits DNA repair and determines mutation risk and anticancer drug effectiveness

PubMed Central

McAdam, Elizabeth; Brem, Reto; Karran, Peter

2016-01-01

The relationship between sun exposure and non-melanoma skin cancer risk is well established. Solar ultraviolet radiation (UV; wavelengths 280-400 nm) is firmly implicated in skin cancer development. Nucleotide excision repair (NER) protects against cancer by removing potentially mutagenic DNA lesions induced by UVB (280-320 nm). How the 20-fold more abundant UVA (320-400 mn) component of solar UV radiation increases skin cancer risk is not understood. We demonstrate here that the contribution of UVA to the effects of UV radiation on cultured human cells is largely independent of its ability to damage DNA. Instead, the effects of UVA reflect the induction of oxidative stress that causes extensive protein oxidation. Because NER proteins are among those damaged, UVA irradiation inhibits NER and increases the cells’ susceptibility to mutation by UVB. NER inhibition is a common consequence of oxidative stress. Exposure to chemical oxidants, treatment with drugs that deplete cellular antioxidants, and interventions that interfere with glucose metabolism to disrupt the supply of cellular reducing power all inhibit NER. Tumor cells are often in a condition of oxidative stress and one effect of the NER inhibition that results from stress-induced protein oxidation is an increased sensitivity to the anticancer drug cisplatin. Statement of implication: Since NER is both a defence against cancer a significant determinant of cell survival after treatment with anticancer drugs, its attenuation by protein damage under conditions of oxidative-stress has implications for both cancer risk and for the effectiveness of anticancer therapy. PMID:27106867

A conformational study of protonated noradrenaline by UV-UV and IR dip double resonance laser spectroscopy combined with an electrospray and a cold ion trap method.

PubMed

Wako, Hiromichi; Ishiuchi, Shun-Ichi; Kato, Daichi; Féraud, Géraldine; Dedonder-Lardeux, Claude; Jouvet, Christophe; Fujii, Masaaki

2017-05-03

The conformer-selected ultraviolet (UV) and infrared (IR) spectra of protonated noradrenaline were measured using an electrospray/cryogenic ion trap technique combined with photo-dissociation spectroscopy. By comparing the UV photo dissociation (UVPD) spectra with the UV-UV hole burning (HB) spectra, it was found that five conformers coexist under ultra-cold conditions. Based on the spectral features of the IR dip spectra of each conformer, two different conformations on the amine side chain were identified. Three conformers (group I) were assigned to folded and others (group II) to extended structures by comparing the observed IR spectra with the calculated ones. Observation of the significantly less-stable extended conformers strongly suggests that the extended structures are dominant in solution and are detected in the gas phase by kinetic trapping. The conformers in each group are assignable to rotamers of OH orientations in the catechol ring. By comparing the UV-UV HB spectra and the calculated Franck-Condon spectra obtained by harmonic vibrational analysis of the S 1 state, with the aid of relative stabilization energies of each conformer in the S 0 state, the absolute orientations of catechol OHs of the observed five conformers were successfully determined. It was found that the 0-0 transition of one folded conformer is red-shifted by about 1000 cm -1 from the others. The significant red-shift was explained by a large contribution of the πσ* state to S 1 in the conformer in which an oxygen atom of the meta-OH group is close to the ammonium group.

Ultraviolet-radiation-induced inflammation promotes angiotropism and metastasis in melanoma

NASA Astrophysics Data System (ADS)

Bald, Tobias; Quast, Thomas; Landsberg, Jennifer; Rogava, Meri; Glodde, Nicole; Lopez-Ramos, Dorys; Kohlmeyer, Judith; Riesenberg, Stefanie; van den Boorn-Konijnenberg, Debby; Hömig-Hölzel, Cornelia; Reuten, Raphael; Schadow, Benjamin; Weighardt, Heike; Wenzel, Daniela; Helfrich, Iris; Schadendorf, Dirk; Bloch, Wilhelm; Bianchi, Marco E.; Lugassy, Claire; Barnhill, Raymond L.; Koch, Manuel; Fleischmann, Bernd K.; Förster, Irmgard; Kastenmüller, Wolfgang; Kolanus, Waldemar; Hölzel, Michael; Gaffal, Evelyn; Tüting, Thomas

2014-03-01

Intermittent intense ultraviolet (UV) exposure represents an important aetiological factor in the development of malignant melanoma. The ability of UV radiation to cause tumour-initiating DNA mutations in melanocytes is now firmly established, but how the microenvironmental effects of UV radiation influence melanoma pathogenesis is not fully understood. Here we report that repetitive UV exposure of primary cutaneous melanomas in a genetically engineered mouse model promotes metastatic progression, independent of its tumour-initiating effects. UV irradiation enhanced the expansion of tumour cells along abluminal blood vessel surfaces and increased the number of lung metastases. This effect depended on the recruitment and activation of neutrophils, initiated by the release of high mobility group box 1 (HMGB1) from UV-damaged epidermal keratinocytes and driven by Toll-like receptor 4 (TLR4). The UV-induced neutrophilic inflammatory response stimulated angiogenesis and promoted the ability of melanoma cells to migrate towards endothelial cells and use selective motility cues on their surfaces. Our results not only reveal how UV irradiation of epidermal keratinocytes is sensed by the innate immune system, but also show that the resulting inflammatory response catalyses reciprocal melanoma-endothelial cell interactions leading to perivascular invasion, a phenomenon originally described as angiotropism in human melanomas by histopathologists. Angiotropism represents a hitherto underappreciated mechanism of metastasis that also increases the likelihood of intravasation and haematogenous dissemination. Consistent with our findings, ulcerated primary human melanomas with abundant neutrophils and reactive angiogenesis frequently show angiotropism and a high risk for metastases. Our work indicates that targeting the inflammation-induced phenotypic plasticity of melanoma cells and their association with endothelial cells represent rational strategies to specifically interfere with metastatic progression.

Lack of chemically induced mutation in repair-deficient mutants of yeast.

PubMed

Prakash, L

1974-12-01

Two genes, rad6 and rad9, that confer radiation sensitivity in the yeast Saccharomyces cerevisiae also greatly reduce the frequency of chemically-induced reversions of a tester mutant cyc1-131, which is a chain initiation mutant in the structural gene determining iso-1-cytochrome c. Mutations induced by ethyl methanesulfonate (EMS), diethyl sulfate (DES), methyl methanesulfonate (MMS), dimethyl sulfate (DMS), nitroquinoline oxide (NQO), nitrosoguanidine (NTG), nitrogen mustard (HN2), beta-propiolactone, and tritiated uridine, as well as mutations induced by ultraviolet light (UV) and ionizing radiation were greatly diminished in strains homozygous for either the rad6 or rad9 gene. Nitrous acid and nitrosoimidazolidone (NIL), on the other hand, were highly mutagenic in these repair-deficient mutants, and at low doses, these mutagens acted with about the same efficiency as in the normal RAD strain. At high doses of either nitrous acid or NIL, however, reversion frequencies were significantly reduced in the two rad mutants compared to normal strains. Although both rad mutants are immutable to about the same extent, the rad9 strains tend to be less sensitive to the lethal effect of chemical mutagens than rad6 strains. It is concluded that yeast requires a functional repair system for mutation induction by chemical agents.

Anaerobically Grown Escherichia coli Has an Enhanced Mutation Rate and Distinct Mutational Spectra

PubMed Central

Shewaramani, Sonal; Finn, Thomas J.; Kassen, Rees; Rainey, Paul B.

2017-01-01

Oxidative stress is a major cause of mutation but little is known about how growth in the absence of oxygen impacts the rate and spectrum of mutations. We employed long-term mutation accumulation experiments to directly measure the rates and spectra of spontaneous mutation events in Escherichia coli populations propagated under aerobic and anaerobic conditions. To detect mutations, whole genome sequencing was coupled with methods of analysis sufficient to identify a broad range of mutational classes, including structural variants (SVs) generated by movement of repetitive elements. The anaerobically grown populations displayed a mutation rate nearly twice that of the aerobic populations, showed distinct asymmetric mutational strand biases, and greater insertion element activity. Consistent with mutation rate and spectra observations, genes for transposition and recombination repair associated with SVs were up-regulated during anaerobic growth. Together, these results define differences in mutational spectra affecting the evolution of facultative anaerobes. PMID:28103245

Specific behavior of the p-aminothiophenol--silver sol system in their Ultra-Violet-Visible (UV-Visible) and Surface Enhanced Raman (SERS) spectra.

PubMed

Firkala, Tamás; Tálas, Emília; Mihály, Judith; Imre, Tímea; Kristyán, Sándor

2013-11-15

The UV-Visible and Surface Enhanced Raman Spectroscopy (SERS) behavior of silver sol (a typical SERS agent) were studied in the presence of different bifunctional thiols such as p-aminothiophenol, p-mercaptobenzoic acid, p-nitrothiophenol, p-aminothiophenol hydrochloride, and 2-mercaptoethylamine hydrochloride in diluted aqueous solution. Our results confirm that the p-aminothiophenol induced aggregation of citrate stabilized silver colloid originates from its electrostatic nature, as well as the azo-bridge formation cannot be the reason of the observed time dependent UV-Visible spectra. Based on our parallel SERS and electrospray ionization mass spectrometry measurements, we have concluded that certain amount of oxidized form of the probe molecule has to be present for the so-called b2-mode enhancement in the SERS spectrum of p-aminothiophenol. Our findings seem to support the idea that the azo-bridge formation is responsible for the b2-mode enhancement in the SERS spectrum of p-aminothiophenol. Copyright © 2013 Elsevier Inc. All rights reserved.

Reduced graphene oxide-germanium quantum dot nanocomposite: electronic, optical and magnetic properties

NASA Astrophysics Data System (ADS)

Amollo, Tabitha A.; Mola, Genene T.; Nyamori, Vincent O.

2017-12-01

Graphene provides numerous possibilities for structural modification and functionalization of its carbon backbone. Localized magnetic moments can, as well, be induced in graphene by the formation of structural defects which include vacancies, edges, and adatoms. In this work, graphene was functionalized using germanium atoms, we report the effect of the Ge ad atoms on the structural, electrical, optical and magnetic properties of graphene. Reduced graphene oxide (rGO)-germanium quantum dot nanocomposites of high crystalline quality were synthesized by the microwave-assisted solvothermal reaction. Highly crystalline spherical shaped germanium quantum dots, of diameter ranging between 1.6-9.0 nm, are anchored on the basal planes of rGO. The nanocomposites exhibit high electrical conductivity with a sheet resistance of up to 16 Ω sq-1. The electrical conductivity is observed to increase with the increase in Ge content in the nanocomposites. High defect-induced magnetization is attained in the composites via germanium adatoms. The evolution of the magnetic moments in the nanocomposites and the coercivity showed marked dependence on the Ge quantum dots size and concentration. Quantum confinement effects is evidenced in the UV-vis absorbance spectra and photoluminescence emission spectra of the nanocomposites which show marked size-dependence. The composites manifest strong absorption in the UV region, strong luminescence in the near UV region, and a moderate luminescence in the visible region.

Thermally and vibrationally induced conformational isomerizations, infrared spectra, and photochemistry of gallic acid in low-temperature matrices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Justino, Licínia L. G., E-mail: liciniaj@ci.uc.pt; Reva, Igor; Fausto, Rui

2016-07-07

Near-infrared (near-IR) narrowband selective vibrational excitation and annealing of gallic acid (3,4,5-trihydroxybenzoic acid) isolated in cryogenic matrices were used to induce interconversions between its most stable conformers. The isomerizations were probed by infrared spectroscopy. An extensive set of quantum chemical calculations, carried out at the DFT(B3LYP)/6-311++G(d,p) level of approximation, was used to undertake a detailed analysis of the ground state potential energy surface of the molecule. This investigation of the molecule conformational space allowed extracting mechanistic insights into the observed annealing- or near-IR-induced isomerization processes. The infrared spectra of the two most stable conformers of gallic acid in N{sub 2},more » Xe, and Ar matrices were fully assigned. Finally, the UV-induced photochemistry of the matrix isolated compound was investigated.« less

Laser-induced optical breakdown spectroscopy of polymer materials based on evaluation of molecular emission bands

NASA Astrophysics Data System (ADS)

Trautner, Stefan; Jasik, Juraj; Parigger, Christian G.; Pedarnig, Johannes D.; Spendelhofer, Wolfgang; Lackner, Johannes; Veis, Pavel; Heitz, Johannes

2017-03-01

Laser-induced breakdown spectroscopy (LIBS) for composition analysis of polymer materials results in optical spectra containing atomic and ionic emission lines as well as molecular emission bands. In the present work, the molecular bands are analyzed to obtain spectroscopic information about the plasma state in an effort to quantify the content of different elements in the polymers. Polyethylene (PE) and a rubber material from tire production are investigated employing 157 nm F2 laser and 532 nm Nd:YAG laser ablation in nitrogen and argon gas background or in air. The optical detection reaches from ultraviolet (UV) over the visible (VIS) to the near infrared (NIR) spectral range. In the UV/VIS range, intense molecular emissions, C2 Swan and CN violet bands, are measured with an Echelle spectrometer equipped with an intensified CCD camera. The measured molecular emission spectra can be fitted by vibrational-rotational transitions by open access programs and data sets with good agreement between measured and fitted spectra. The fits allow determining vibrational-rotational temperatures. A comparison to electronic temperatures Te derived earlier from atomic carbon vacuum-UV (VUV) emission lines show differences, which can be related to different locations of the atomic and molecular species in the expanding plasma plume. In the NIR spectral region, we also observe the CN red bands with a conventional CDD Czerny Turner spectrometer. The emission of the three strong atomic sulfur lines between 920 and 925 nm is overlapped by these bands. Fitting of the CN red bands allows a separation of both spectral contributions. This makes a quantitative evaluation of sulfur contents in the start material in the order of 1 wt% feasible.

UV-B inhibition of hypocotyl growth in etiolated Arabidopsis thaliana seedlings is a consequence of cell cycle arrest initiated by photodimer accumulation

PubMed Central

Biever, Jessica J.; Brinkman, Doug; Gardner, Gary

2014-01-01

Ultraviolet (UV) radiation is an important constituent of sunlight that determines plant morphology and growth. It induces photomorphogenic responses but also causes damage to DNA. Arabidopsis mutants of the endonucleases that function in nucleotide excision repair, xpf-3 and uvr1-1, showed hypersensitivity to UV-B (280–320nm) in terms of inhibition of hypocotyl growth. SOG1 is a transcription factor that functions in the DNA damage signalling response after γ-irradiation. xpf mutants that carry the sog1-1 mutation showed hypocotyl growth inhibition after UV-B irradiation similar to the wild type. A DNA replication inhibitor, hydroxyurea (HU), also inhibited hypocotyl growth in etiolated seedlings, but xpf-3 was not hypersensitive to HU. UV-B irradiation induced accumulation of the G2/M-specific cell cycle reporter construct CYCB1;1-GUS in wild-type Arabidopsis seedlings that was consistent with the expected accumulation of photodimers and coincided with the time course of hypocotyl growth inhibition after UV-B treatment. Etiolated mutants of UVR8, a recently described UV-B photoreceptor gene, irradiated with UV-B showed inhibition of hypocotyl growth that was not different from that of the wild type, but they lacked UV-B-specific expression of chalcone synthase (CHS), as expected from previous reports. CHS expression after UV-B irradiation was not different in xpf-3 compared with the wild type, nor was it altered after HU treatment. These results suggest that hypocotyl growth inhibition by UV-B light in etiolated Arabidopsis seedlings, a photomorphogenic response, is dictated by signals originating from UV-B absorption by DNA that lead to cell cycle arrest. This process occurs distinct from UVR8 and its signalling pathway responsible for CHS induction. PMID:24591052

Effects of a high-pressure treatment on the wheat alpha-amylase inhibitor and its relationship to elimination of allergenicity

NASA Astrophysics Data System (ADS)

Yamamoto, S.; Takanohashi, K.; Hara, T.; Odani, S.; Suzuki, A.; Nishiumi, T.

2010-03-01

In this study, the effects of high-pressure treatment on structure and allergeincity of alpha amylase inhibitor (a-AI) were investigated. The pressure-induced structural changes of α-AI were estimated by fluorescence spectra and by fourth derivative UV-spectroscopy for probed tyrosine residues and by circular dichroism (CD) spectroscopy. The changes in the tertiary structure detected by fluorescence spectra and by fourth derivative UV-spectroscopy under high pressure were indicated at over 300 MPa. Measurements of CD spectroscopy suggested that the effects of a high-pressure treatment on changes in the secondary structure of α-AI were little. From our results, pressure-induced changes of the α-AI structure were not apparent. On the other hands, the IgE-specific binding activities of pressurized α-AI to sera from allergic patients against wheat, which is estimated by observations of dot-blotting, were decreased by high-pressure treatment. It is known that the pressure-induced elimination of allergenicity is related to the tertiary structural changes of allergen molecules. This study are suspected that the epitopes of α-AI do not contain tyrosine residues, and thus the decrease of IgE-specific binding activities is probably caused by the tertiary structural changes of these parts of α-AI.

VUV absorption spectroscopy of bacterial spores and DNA components

NASA Astrophysics Data System (ADS)

Fiebrandt, Marcel; Lackmann, Jan-Wilm; Raguse, Marina; Moeller, Ralf; Awakowicz, Peter; Stapelmann, Katharina

2017-01-01

Low-pressure plasmas can be used to inactivate bacterial spores and sterilize goods for medical and pharmaceutical applications. A crucial factor are damages induced by UV and VUV radiation emitted by the plasma. To analyze inactivation processes and protection strategies of spores, absorption spectra of two B. subtilis strains are measured. The results indicate, that the inner and outer coat of the spore significantly contribute to the absorption of UV-C and also of the VUV, protecting the spore against radiation based damages. As the sample preparation can significantly influence the absorption spectra due to salt residues, the cleaning procedure and sample deposition is tested for its reproducibility by measuring DNA oligomers and pUC18 plasmid DNA. The measurements are compared and discussed with results from the literature, showing a strong decrease of the salt content enabling the detection of absorption structures in the samples.

The pso4-1 mutation reduces spontaneous mitotic gene conversion and reciprocal recombination in Saccharomyces cerevisiae.

PubMed

Meira, L B; Fonseca, M B; Averbeck, D; Schenberg, A C; Henriques, J A

1992-11-01

Spontaneous mitotic recombination was examined in the haploid pso4-1 mutant of Saccharomyces cerevisiae and in the corresponding wild-type strain. Using a genetic system involving a duplication of the his4 gene it was shown that the pso4-1 mutation decreases at least fourfold the spontaneous rate of mitotic recombination. The frequency of spontaneous recombination was reduced tenfold in pso4-1 strains, as previously observed in the rad52-1 mutant. However, whereas the rad52-1 mutation specifically reduces gene conversion, the pso4-1 mutation reduces both gene conversion and reciprocal recombination. Induced mitotic recombination was also studied in pso4-1 mutant and wild-type strains after treatment with 8-methoxypsoralen plus UVA and 254 nm UV irradiation. Consistent with previous results, the pso4-1 mutation was found strongly to affect recombination induction.

Recharging processes, radiation induced strain and changes of OH - bands under H + ion implantation in Ti doped lithium niobate

NASA Astrophysics Data System (ADS)

Kumar, P.; Moorthy Babu, S.; Bhaumik, I.; Ganesamoorthy, S.; Karnal, A. K.; Kumar, Praveen; Rodrigues, G. O.; Sulania, I.; Kanjilal, D.; Pandey, A. K.; Raman, R.

2010-01-01

A systematic analysis of variations in structural and optical characteristics of Z-cut plates of titanium doped congruent lithium niobate single crystals implanted with 120 keV proton beam at various fluences of 10 15, 10 16 and 10 17 protons/cm 2 is presented. Through, high resolution X-ray diffraction, atomic force microscopy, Fourier transform infrared and UV-visible-NIR analysis of congruent lithium niobate, the correlation of properties before and after implantation are discussed. HRXRD (0 0 6) reflection by Triple Crystal Mode shows that both tensile and compressive strain peak are produced by the high fluence implantation. A distinct tensile peak was observed from implanted region for a fluence of 10 16 protons/cm 2. AFM micrographs indicate mountain ridges, bumps and protrusions on target surface on implantation. UV-visible-NIR spectra reveal an increase in charge transfer between Ti 3+/Ti 4+ and ligand oxygen for implantation with 10 15 protons/cm 2, while spectra for higher fluence implanted samples show complex absorption band in the region from 380-1100 nm. Variations of OH - stretching vibration mode were observed for cLN Pure, cLNT2% virgin, and implanted samples with FTIR spectra. The concentration of OH - ion before and after implantation was calculated from integral absorption intensity. The effect of 120 keV proton implantation induced structural, surface and optical studies were correlated.

UV-vis spectroscopic studies of CaF2 photo-thermo-refractive glass

NASA Astrophysics Data System (ADS)

Stoica, Martina; Herrmann, Andreas; Hein, Joachim; Rüssel, Christian

2016-12-01

A photo-thermo-refractive glass based on the system Na2O/K2O/CaO/CaF2/Al2O3/ZnO/SiO2 doped with Ag2O, CeO2, SnO2, Sb2O3 and KBr was investigated. This glass undergoes a permanent refractive index change after UV irradiation and subsequent two step heat treatment at temperatures above Tg. This is due to the formation of Ag metal clusters which act as nucleation centers for CaF2 crystallization. Oxidation of Ce3+ by UV light is the initial reaction and acts as photosensitizer in the glass. The UV-vis absorption spectra during this photo-induced crystallization process were measured. The spectral components that form the absorption spectra of cerium were studied in detail by a band separation with Gaussian functions. Deconvolution of the cerium absorption bands shows an envelope of five spectral components for the trivalent cerium due to the 4f-5d transitions and two spectral components for the tetravalent cerium caused by charge transfer transitions. The effect of different dopants and melting conditions on the photo-thermal process were studied to investigate the influence of glass technology on the photoprocess.

Detecting Kerogen as a Biosignature Using Colocated UV Time-Gated Raman and Fluorescence Spectroscopy.

PubMed

Shkolyar, Svetlana; Eshelman, Evan J; Farmer, Jack D; Hamilton, David; Daly, Michael G; Youngbull, Cody

2018-04-01

The Mars 2020 mission will analyze samples in situ and identify any that could have preserved biosignatures in ancient habitable environments for later return to Earth. Highest priority targeted samples include aqueously formed sedimentary lithologies. On Earth, such lithologies can contain fossil biosignatures as aromatic carbon (kerogen). In this study, we analyzed nonextracted kerogen in a diverse suite of natural, complex samples using colocated UV excitation (266 nm) time-gated (UV-TG) Raman and laser-induced fluorescence spectroscopies. We interrogated kerogen and its host matrix in samples to (1) explore the capabilities of UV-TG Raman and fluorescence spectroscopies for detecting kerogen in high-priority targets in the search for possible biosignatures on Mars; (2) assess the effectiveness of time gating and UV laser wavelength in reducing fluorescence in Raman spectra; and (3) identify sample-specific issues that could challenge rover-based identifications of kerogen using UV-TG Raman spectroscopy. We found that ungated UV Raman spectroscopy is suited to identify diagnostic kerogen Raman bands without interfering fluorescence and that UV fluorescence spectroscopy is suited to identify kerogen. These results highlight the value of combining colocated Raman and fluorescence spectroscopies, similar to those obtainable by SHERLOC on Mars 2020, to strengthen the confidence of kerogen detection as a potential biosignature in complex natural samples. Key Words: Raman spectroscopy-Laser-induced fluorescence spectroscopy-Mars Sample Return-Mars 2020 mission-Kerogen-Biosignatures. Astrobiology 18, 431-453.

Photoactivated UVR8-COP1 Module Determines Photomorphogenic UV-B Signaling Output in Arabidopsis

PubMed Central

Ouyang, Xinhao; Chen, Liangbi; Deng, Xing Wang

2014-01-01

In Arabidopsis, ultraviolet (UV)-B-induced photomorphogenesis is initiated by a unique photoreceptor UV RESISTANCE LOCUS 8 (UVR8) which utilizes its tryptophan residues as internal chromophore to sense UV-B. As a result of UV-B light perception, the UVR8 homodimer shaped by its arginine residues undergoes a conformational switch of monomerization. Then UVR8 associates with the CONSTITUTIVELY PHOTOMORPHOGENIC 1-SUPPRESSOR OF PHYA (COP1-SPA) core complex(es) that is released from the CULLIN 4-DAMAGED DNA BINDING PROTEIN 1 (CUL4-DDB1) E3 apparatus. This association, in turn, causes COP1 to convert from a repressor to a promoter of photomorphogenesis. It is not fully understood, however, regarding the biological significance of light-absorbing and dimer-stabilizing residues for UVR8 activity in photomorphogenic UV-B signaling. Here, we take advantage of transgenic UVR8 variants to demonstrate that two light-absorbing tryptophans, W233 and W285, and two dimer-stabilizing arginines, R286 and R338, play pivotal roles in UV-B-induced photomorphogenesis. Mutation of each residue results in alterations in UV-B light perception, UVR8 monomerization and UVR8-COP1 association in response to photomorphogenic UV-B. We also identify and functionally characterize two constitutively active UVR8 variants, UVR8W285A and UVR8R338A, whose photobiological activities are enhanced by the repression of CUL4, a negative regulator in this pathway. Based on our molecular and biochemical evidence, we propose that the UVR8-COP1 affinity in plants critically determines the photomorphogenic UV-B signal transduction coupling with UVR8-mediated UV-B light perception. PMID:24651064

Chemical and UV Mutagenesis.

PubMed

Bose, Jeffrey L

2016-01-01

The ability to create mutations is an important step towards understanding bacterial physiology and virulence. While targeted approaches are invaluable, the ability to produce genome-wide random mutations can lead to crucial discoveries. Transposon mutagenesis is a useful approach, but many interesting mutations can be missed by these insertions that interrupt coding and noncoding sequences due to the integration of an entire transposon. Chemical mutagenesis and UV-based random mutagenesis are alternate approaches to isolate mutations of interest with the potential of only single nucleotide changes. Once a standard method, difficulty in identifying mutation sites had decreased the popularity of this technique. However, thanks to the recent emergence of economical whole-genome sequencing, this approach to making mutations can once again become a viable option. Therefore, this chapter provides an overview protocol for random mutagenesis using UV light or DNA-damaging chemicals.

Phosphorylation of Nucleotide Excision Repair Factor Xeroderma Pigmentosum Group A by Ataxia Telangiectasia Mutated and Rad3-Related-Dependent Checkpoint Pathway Promotes Cell Survival in Response to UV Irradiation

PubMed Central

Wu, Xiaoming; Shell, Steven M.; Yang, Zhengguan; Zou, Yue

2006-01-01

DNA damage triggers complex cellular responses in eukaryotic cells, including initiation of DNA repair and activation of cell cycle checkpoints. In addition to inducing cell cycle arrest, checkpoint also has been suggested to modulate a variety of other cellular processes in response to DNA damage. In this study, we present evidence showing that the cellular function of xeroderma pigmentosum group A (XPA), a major nucleotide excision repair (NER) factor, could be modulated by checkpoint kinase ataxia-telangiectasia mutated and Rad3-related (ATR) in response to UV irradiation. We observed the apparent interaction and colocalization of XPA with ATR in response to UV irradiation. We showed that XPA was a substrate for in vitro phosphorylation by phosphatidylinositol-3-kinase-related kinase family kinases whereas in cells XPA was phosphorylated in an ATR-dependent manner and stimulated by UV irradiation. The Ser196 of XPA was identified as a biologically significant residue to be phosphorylated in vivo. The XPA-deficient cells complemented with XPA-S196A mutant, in which Ser196 was substituted with an alanine, displayed significantly higher UV sensitivity compared with the XPA cells complemented with wild-type XPA. Moreover, substitution of Ser196 with aspartic acid for mimicking the phosphorylation of XPA increased the cell survival to UV irradiation. Taken together, our results revealed a potential physical and functional link between NER and the ATR-dependent checkpoint pathway in human cells and suggested that the ATR checkpoint pathway could modulate the cellular activity of NER through phosphorylation of XPA at Ser196 on UV irradiation. PMID:16540648

Induction of mutations by bismuth-212 alpha particles at two genetic loci in human B-lymphoblasts.

PubMed

Metting, N F; Palayoor, S T; Macklis, R M; Atcher, R W; Liber, H L; Little, J B

1992-12-01

The human lymphoblast cell line TK6 was exposed to the alpha-particle-emitting radon daughter 212Bi by adding DTPA-chelated 212Bi directly to the cell suspension. Cytotoxicity and mutagenicity at two genetic loci were measured, and the molecular nature of mutant clones was studied by Southern blot analysis. Induced mutant fractions were 2.5 x 10(-5)/Gy at the hprt locus and 3.75 x 10(-5)/Gy at the tk locus. Molecular analysis of HPRT- mutant DNAs showed a high frequency (69%) of clones with partial or full deletions of the hprt gene among radiation-induced mutants compared with spontaneous mutants (31%). Chi-squared analyses of mutational spectra show a significant difference (P < or = 0.005) between spontaneous mutants and alpha-particle-induced mutants. Comparison with published studies of accelerator-produced heavy-ion exposures of TK6 cells indicates that the induction of mutations at the hprt locus, and perhaps a subset of mutations at the tk locus, is a simple linear function of particle fluence regardless of the ion species or its LET.

Genetic transformation of Neurospora tetrasperma, demonstration of repeat-induced point mutation (RIP) in self-crosses and a screen for recessive RIP-defective mutants.

PubMed Central

Bhat, Ashwin; Tamuli, Ranjan; Kasbekar, Durgadas P

2004-01-01

The pseudohomothallic fungus Neurospora tetrasperma is naturally resistant to the antibiotic hygromycin. We discovered that mutation of its erg-3 (sterol C-14 reductase) gene confers a hygromycin-sensitive phenotype that can be used to select transformants on hygromycin medium by complementation with the N. crassa erg-3+ and bacterial hph genes. Cotransformation of hph with PCR-amplified DNA of other genes enabled us to construct strains duplicated for the amplified DNA. Using transformation we constructed self-fertile strains that were homoallelic for an ectopic erg-3+ transgene and a mutant erg-3 allele at the endogenous locus. Self-crosses of these strains yielded erg-3 mutant ascospores that produced colonies with the characteristic morphology on Vogel's sorbose agar described previously for erg-3 mutants of N. crassa. The mutants were generated by repeat-induced point mutation (RIP), a genome defense process that causes numerous G:C to A:T mutations in duplicated DNA sequences. Homozygosity for novel recessive RIP-deficient mutations was signaled by self-crosses of erg-3-duplication strains that fail to produce erg-3 mutant progeny. Using this assay we isolated a UV-induced mutant with a putative partial RIP defect. RIP-induced mutants were isolated in rid-1 and sad-1, which are essential genes, respectively, for RIP and another genome defense mechanism called meiotic silencing by unpaired DNA. PMID:15280231

UVB-induced mutagenesis in hairless {lambda}lacZ-transgenic mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frijhoff, A.F.W.; Rebel, H.; Mientjes, E.J.

UVB-induced mutagenesis was studied in hairless 40.6 transgenic mice (Muta{trademark}Mouse), which contain the {lambda}gt1OlacZ shuttle vector as a target for mutagenesis. Mice were exposed at the dorsal side to either single doses of 200, 500, 800, or 1000 J/m{sup 2} UVB or to two successive irradiations of either 200 and 800 J/m{sup 2} UVB, with intervals of 1,3, or 5 days, or to 800 and 200 J/m{sup 2} UVB with a 5-day interval. At 23 days after the last exposure, lacZ mutant frequencies (MF) were determined in the epidermis. The lacZ MF increased linearly with increasing dose of UVB. Themore » mutagenic effect of two successive irradiations appeared to be additive. The UV-induced mutation spectrum was dominated by G:C{r_arrow}A:T transitions at dipyrimidine sites. DNA-sequence analysis of spontaneously mutated phages showed a diverse spectrum consisting of insertions, deletions and G:C {r_arrow} A:T transitions at CpG sites. the results indicate that the hairless {lambda}lacZ-transgenic mouse is a suitable in vivo model for studying UVB-induced mutations. 29 refs., 5 tabs.« less

The Spectrum of Replication Errors in the Absence of Error Correction Assayed Across the Whole Genome of Escherichia coli.

PubMed

Niccum, Brittany A; Lee, Heewook; MohammedIsmail, Wazim; Tang, Haixu; Foster, Patricia L

2018-06-15

When the DNA polymerase that replicates the Escherichia coli chromosome, DNA Pol III, makes an error, there are two primary defenses against mutation: proofreading by the epsilon subunit of the holoenzyme and mismatch repair. In proofreading deficient strains, mismatch repair is partially saturated and the cell's response to DNA damage, the SOS response, may be partially induced. To investigate the nature of replication errors, we used mutation accumulation experiments and whole genome sequencing to determine mutation rates and mutational spectra across the entire chromosome of strains deficient in proofreading, mismatch repair, and the SOS response. We report that a proofreading-deficient strain has a mutation rate 4,000-fold greater than wild-type strains. While the SOS response may be induced in these cells, it does not contribute to the mutational load. Inactivating mismatch repair in a proofreading-deficient strain increases the mutation rate another 1.5-fold. DNA polymerase has a bias for converting G:C to A:T base pairs, but proofreading reduces the impact of these mutations, helping to maintain the genomic G:C content. These findings give an unprecedented view of how polymerase and error-correction pathways work together to maintain E. coli' s low mutation rate of 1 per thousand generations. Copyright © 2018, Genetics.

Emission spectra of photoionized plasmas induced by intense EUV pulses: Experimental and theoretical investigations

NASA Astrophysics Data System (ADS)

Saber, Ismail; Bartnik, Andrzej; Skrzeczanowski, Wojciech; Wachulak, Przemysław; Jarocki, Roman; Fiedorowicz, Henryk

2017-03-01

Experimental measurements and numerical modeling of emission spectra in photoionized plasma in the ultraviolet and visible light (UV/Vis) range for noble gases have been investigated. The photoionized plasmas were created using laser-produced plasma (LPP) extreme ultraviolet (EUV) source. The source was based on a gas puff target; irradiated with 10ns/10J/10Hz Nd:YAG laser. The EUV radiation pulses were collected and focused using grazing incidence multifoil EUV collector. The laser pulses were focused on a gas stream, injected into a vacuum chamber synchronously with the EUV pulses. Irradiation of gases resulted in a formation of low temperature photoionized plasmas emitting radiation in the UV/Vis spectral range. Atomic photoionized plasmas produced this way consisted of atomic and ionic with various ionization states. The most dominated observed spectral lines originated from radiative transitions in singly charged ions. To assist in a theoretical interpretation of the measured spectra, an atomic code based on Cowan's programs and a collisional-radiative PrismSPECT code have been used to calculate the theoretical spectra. A comparison of the calculated spectral lines with experimentally obtained results is presented. Electron temperature in plasma is estimated using the Boltzmann plot method, by an assumption that a local thermodynamic equilibrium (LTE) condition in the plasma is validated in the first few ionization states. A brief discussion for the measured and computed spectra is given.

Mutagenesis in human cells with accelerated H and Fe ions

NASA Technical Reports Server (NTRS)

Kronenberg, Amy

1994-01-01

The overall goals of this research were to determine the risks of mutation induction and the spectra of mutations induced by energetic protons and iron ions at two loci in human lymphoid cells. During the three year grant period the research has focused in three major areas: (1) the acquisition of sufficient statistics for human TK6 cell mutation experiments using Fe ions (400 MeV/amu), Fe ions (600 MeV/amu) and protons (250 MeV/amu); (2) collection of thymidine kinase- deficient (tk) mutants or hypoxanthine phosphoribosyltransferase deficient (hprt) mutants induced by either Fe 400 MeV/amu, Fe 600 MeV/amu, or H 250 MeV/amu for subsequent molecular analysis; and (3) molecular characterization of mutants isolated after exposure to Fe ions (600 MeV/amu). As a result of the shutdown of the BEVALAC heavy ion accelerator in December 1992, efforts were rearranged somewhat in time to complete our dose-response studies and to complete mutant collections in particular for the Fe ion beams prior to the shutdown. These goals have been achieved. A major effort was placed on collection, re-screening, and archiving of 3 different series of mutants for the various particle beam exposures: tk-ng mutants, tk-sg mutants, and hprt-deficient mutants. Where possible, groups of mutants were isolated for several particle fluences. Comparative analysis of mutation spectra has occured with characterization of the mutation spectrum for hprt-deficient mutants obtained after exposure of TK6 cells to Fe ions (600 MeV/amu) and a series of spontaneous mutants.

Rapid long-wave infrared laser-induced breakdown spectroscopy measurements using a mercury-cadmium-telluride linear array detection system.

PubMed

Yang, Clayton S-C; Brown, Eiei; Kumi-Barimah, Eric; Hommerich, Uwe; Jin, Feng; Jia, Yingqing; Trivedi, Sudhir; D'souza, Arvind I; Decuir, Eric A; Wijewarnasuriya, Priyalal S; Samuels, Alan C

2015-11-20

In this work, we develop a mercury-cadmium-telluride linear array detection system that is capable of rapidly capturing (∼1-5  s) a broad spectrum of atomic and molecular laser-induced breakdown spectroscopy (LIBS) emissions in the long-wave infrared (LWIR) region (∼5.6-10  μm). Similar to the conventional UV-Vis LIBS, a broadband emission spectrum of condensed phase samples covering the whole 5.6-10 μm region can be acquired from just a single laser-induced microplasma or averaging a few single laser-induced microplasmas. Atomic and molecular signature emission spectra of solid inorganic and organic tablets and thin liquid films deposited on a rough asphalt surface are observed. This setup is capable of rapidly probing samples "as is" without the need of elaborate sample preparation and also offers the possibility of a simultaneous UV-Vis and LWIR LIBS measurement.

[The UV-Vis spectra and substituent effect of organoimido derivatives of polyoxometalates].

PubMed

Li, Qiang; Wei, Yong-ge; Wang, Yuan; Guo, Hong-you

2005-06-01

In the presence of a carbodiimine, i.e. DCC, a series of organoimido derivatives of polyoxometalates have been synthesized via the reaction of [alpha-Mo8O26]4- with aromatic amines and its hydrochloride salt. Elemental analysis, IR, 1H-NMR and UV-Vis spectra were used to characterize those hybrids, in particular their UV-Vis spectra have been studied. The results show that typical metal-ligand charge transfer (MLCT) transitions occur in the organic-inorganic hybrid molecules. There is a good linear relationship between the shift of UV-Vis absorptions (delta lamda max) and conjugation effect of the p-substituted group (sigmaR).

Methylglyoxal induced glycation and aggregation of human serum albumin: Biochemical and biophysical approach.

PubMed

Ahmed, Azaj; Shamsi, Anas; Khan, Mohd Shahnawaz; Husain, Fohad Mabood; Bano, Bilqees

2018-07-01

Serum protein glycation and formation of advanced glycation end products (AGEs) correlates with many diseases viz. diabetes signifying the importance of studying the glycation pattern of serum proteins. In our present study, methylglyoxal was investigated for its effect on the structure of human serum albumin (HSA); exploring the formation of AGEs and aggregates of HSA. The analytical tools employed includes intrinsic and extrinsic fluorescence, UV spectroscopy, far UV circular dichroism, Thioflavin T fluorescence, congo red binding, polyacrylamide gel electrophoresis (PAGE). UV and fluorescence spectroscopy revealed the structural transition of native HSA evident by new peaks and increased absorbance in UV spectra and quenched fluorescence in the presence of MG. Far UV CD spectroscopy revealed MG induced secondary structural alteration evident by reduced α-helical content. AGEs formation was confirmed by AGEs specific fluorescence. Increased ThT fluorescence and CR absorbance of 10mM MG incubated HSA suggests that glycated HSA results in the formation of aggregates of HSA. SEM and TEM were reported to have an insight of these aggregates. Molecular docking was also utilized to see site specific interaction of MG-HSA. This study is clinically significant as HSA is a clinically relevant protein which plays a crucial role in many diseases. Copyright © 2018 Elsevier B.V. All rights reserved.

Binding properties of food colorant allura red with human serum albumin in vitro.

PubMed

Wang, Langhong; Zhang, Guowen; Wang, Yaping

2014-05-01

Allura red (AR) is a widely used colorant in food industry, but may have a potential security risk. In this study, the properties of interaction between AR and human serum albumin (HSA) in vitro were determined by fluorescence, UV-Vis absorption and circular dichroism (CD) spectroscopy combining with multivariate curve resolution-alternating least squares (MCR-ALS) chemometrics and molecular modeling approaches. An expanded UV-Vis data matrix was resolved by MCR-ALS method, and the concentration profiles and pure spectra for the three reaction components (AR, HSA, and AR-HSA complex) of the system were then successfully obtained to evaluate the progress interaction of AR with HSA. The calculated thermodynamic parameters indicated that hydrogen binding and hydrophobic interactions played major roles in the binding process, and the interaction induced a decrease in the protein surface hydrophobicity. The competitive experiments revealed that AR mainly located in Sudlow's site I of HSA, and this result was further supported by molecular modeling studies. Analysis of CD spectra found that the addition of AR induced the conformational changes of HSA. This study have provided new insight into the mechanism of interaction between AR and HSA.

High-Resolution Genome-Wide Analysis of Irradiated (UV and γ-Rays) Diploid Yeast Cells Reveals a High Frequency of Genomic Loss of Heterozygosity (LOH) Events

PubMed Central

St. Charles, Jordan; Hazkani-Covo, Einat; Yin, Yi; Andersen, Sabrina L.; Dietrich, Fred S.; Greenwell, Patricia W.; Malc, Ewa; Mieczkowski, Piotr; Petes, Thomas D.

2012-01-01

In diploid eukaryotes, repair of double-stranded DNA breaks by homologous recombination often leads to loss of heterozygosity (LOH). Most previous studies of mitotic recombination in Saccharomyces cerevisiae have focused on a single chromosome or a single region of one chromosome at which LOH events can be selected. In this study, we used two techniques (single-nucleotide polymorphism microarrays and high-throughput DNA sequencing) to examine genome-wide LOH in a diploid yeast strain at a resolution averaging 1 kb. We examined both selected LOH events on chromosome V and unselected events throughout the genome in untreated cells and in cells treated with either γ-radiation or ultraviolet (UV) radiation. Our analysis shows the following: (1) spontaneous and damage-induced mitotic gene conversion tracts are more than three times larger than meiotic conversion tracts, and conversion tracts associated with crossovers are usually longer and more complex than those unassociated with crossovers; (2) most of the crossovers and conversions reflect the repair of two sister chromatids broken at the same position; and (3) both UV and γ-radiation efficiently induce LOH at doses of radiation that cause no significant loss of viability. Using high-throughput DNA sequencing, we also detected new mutations induced by γ-rays and UV. To our knowledge, our study represents the first high-resolution genome-wide analysis of DNA damage-induced LOH events performed in any eukaryote. PMID:22267500

Impact effects of gamma irradiation on the optical and FT infrared absorption spectra of some Nd3+-doped soda lime phosphate glasses

NASA Astrophysics Data System (ADS)

Marzouk, M. A.; Elkashef, I. M.; Elbatal, H. A.

2018-04-01

The main aim of the present work is to study by two collective optical and FTIR spectral measurements some prepared Nd2O3-doped soda lime phosphate glasses before and after gamma irradiation with dose (9 Mrad). The spectral data reveal two strong UV absorption peaks which are correlated with unavoidable trace iron impurities beside extended additional characteristic bands due to Nd3+ ions. Gamma irradiation on the undoped glass produces slight decrease of the intensity of the UV absorption and the generation of an induced visible band and these effects are controlled with two photochemical reduction of some Fe3+ ions to Fe2+ ions together with the formation of nonbridging oxygen hole center (NBOHC) or phosphorous oxygen hole center (POHC). The impact effect of gamma irradiation on the spectra of Nd2O3-doped glasses is limited due to suggested shielding behavior of neodymium ions. FT-infrared spectra show vibrational modes due to main Q2-Q3 phosphate groups and the response of gamma irradiation of the IR spectra is low and the limited variations are related to suggested changes in some bond angles and bond lengths which cause the observed decrease to the intensities of some IR bands.

UV photoprocessing of CO2 ice: a complete quantification of photochemistry and photon-induced desorption processes

NASA Astrophysics Data System (ADS)

Martín-Doménech, R.; Manzano-Santamaría, J.; Muñoz Caro, G. M.; Cruz-Díaz, G. A.; Chen, Y.-J.; Herrero, V. J.; Tanarro, I.

2015-12-01

Context. Ice mantles that formed on top of dust grains are photoprocessed by the secondary ultraviolet (UV) field in cold and dense molecular clouds. UV photons induce photochemistry and desorption of ice molecules. Experimental simulations dedicated to ice analogs under astrophysically relevant conditions are needed to understand these processes. Aims: We present UV-irradiation experiments of a pure CO2 ice analog. Calibration of the quadrupole mass spectrometer allowed us to quantify the photodesorption of molecules to the gas phase. This information was added to the data provided by the Fourier transform infrared spectrometer on the solid phase to obtain a complete quantitative study of the UV photoprocessing of an ice analog. Methods: Experimental simulations were performed in an ultra-high vacuum chamber. Ice samples were deposited onto an infrared transparent window at 8K and were subsequently irradiated with a microwave-discharged hydrogen flow lamp. After irradiation, ice samples were warmed up until complete sublimation was attained. Results: Photolysis of CO2 molecules initiates a network of photon-induced chemical reactions leading to the formation of CO, CO3, O2, and O3. During irradiation, photon-induced desorption of CO and, to a lesser extent, O2 and CO2 took place through a process called indirect desorption induced by electronic transitions, with maximum photodesorption yields (Ypd) of ~1.2 × 10-2 molecules incident photon-1, ~9.3 × 10-4 molecules incident photon-1, and ~1.1 × 10-4 molecules incident photon-1, respectively. Conclusions: Calibration of mass spectrometers allows a direct quantification of photodesorption yields instead of the indirect values that were obtained from infrared spectra in most previous works. Supplementary information provided by infrared spectroscopy leads to a complete quantification, and therefore a better understanding, of the processes taking place in UV-irradiated ice mantles. Appendix A is available in electronic form at http://www.aanda.org

Genotoxic action of sunlight upon Bacillus subtilis spores: monitoring studies at Tokyo, Japan.

PubMed

Munakata, N

1989-12-01

Samples of Bacillus subtilis spores dried on membrane filter were exposed to natural sunlight from solar-noon time at Tokyo. The survival and mutation induction of wild-type (UVR) and repair-deficient (UVS) spores were determined on 66 occasions since 1979. Two of the values were considered to be useful in monitoring solar UV intensity; the inverse of the time (in minutes) of exposure to kill 63% of the UVS spores ("sporocidal index") and the induced mutation frequency at 60 minutes of exposure of the UVR spores ("mutagenic index"). Both values were varied greatly due to time of a year, weather and other conditions. Estimates of year-round changes under clear skies were obtained by connecting the maximum values attained in these years. In these curves, there are more than 7-fold differences in the genotoxicity between winter and summer months, with major increases observed in early spring and decreases through autumn. Using a series of UV cut-off filters, the wavelengths most effective for the sporocidal actions were estimated to be in the range of 308-325 nm, shorter wavelengths being effective when the genotoxicity was higher. Sunburn meter of Robertson-Berger type seems to respond to slightly longer wavelength components of the solar spectrum. However, a reasonable correlation was obtained between the reading of the meter and the sporocidal index.

The ultraviolet-bright stars of Omega Centauri, M3, and M13

NASA Technical Reports Server (NTRS)

Landsman, Wayne B.; O'Connell, Robert W.; Whitney, Jonathan H.; Bohlin, Ralph C.; Hill, Robert S.; Maran, Stephen P.; Parise, Ronald A.; Roberts, Morton S.; Smith, Andrew A.; Stecher, Theodore P.

1992-01-01

Two new UV-bright stars detected within 2 arcmin of the center of Omega Cen are spectroscopically investigated with the short-wavelength spectrograph of the IUE. The IUE spectra of the UV-bright stars UIT-1 and UIT-2 in the core of Omega Cen superficially resemble those of Population I mid-B stars. The absorption lines of the core UV-bright stars are significantly weaker than in Population I stars, consistent with their membership in the cluster. Synthetic spectra calculated from low-metallicity Kurucz model stellar atmospheres are compared with the spectra. These objects are insufficiently luminous to be classical hydrogen-burning post-AGB stars. They may be evolved hot horizontal branch stars which have been brightened by more than 3 mag since leaving the zero-age horizontal branch. It is inferred from the spectra and luminosity of the core UV-bright stars that similar objects could provide the source of the UV light in elliptical galaxies.

Novel mutations in β-tubulin gene in Trichoderma harzianum mutants resistant to methyl benzimidazol-2-yl carbamate.

PubMed

Li, M; Zhang, H Y; Liang, B

2013-01-01

Twelve-low resistant (LR) mutants of Trichoderma harzianum with the capability of grow fast at 0.8 μg/mL methyl benzimidazol-2-yl carbamate (MBC) were obtained using UV mutagenesis. MR and HR mutants which could grow fast at 10 and 100 μg/mL MBC, respectively, were isolated by step-up selection protocols in which UV-treated mutants were induced and mycelial sector screening was made in plates with growth medium. Subsequently, β-tubulin genes of 14 mutants were cloned to describe-the molecular lesion likely to be responsible-for MBC resistance. Comparison of the β-tubulin sequences of the mutant and sensitive strains of T. harzianum revealed 2 new MBC-binding sites differed from those in other plant pathogens. A single mutation at-amino acid 168, having Phe (TTC) instead of Ser (TCC)', was demonstrated for the HR mutant; a double mutation in amino acid 13 resulting in the substitution of Gly (GGC) by Val (GTG) was observed in β-tubulin gene of MR mutant. On the other hand, no substitutions were identified in the β-tubulin gene and its 5'-flanking regions in 12 LR mutants of T. harzianum.

Effects of aspartic acid and potassium chloride on arginine kinase from shrimp.

PubMed

Tang, Hong-min; Yang, Yin-ye; Zhang, Song-fu

2006-12-15

The aspartic acid (Asp)-induced unfolding and the salt-induced folding of arginine kinase (AK) were studied in terms of enzyme activity, intrinsic fluorescence emission spectra, 1-anilino-8-naphthalenesulfonate (ANS) fluorescence spectra and far-UV circular dichroism (CD) spectra. The results showed that Asp caused inactivation and unfolding of AK with no aggregation during AK denaturation. The unfolding of the whole molecule and the inactivation of AK in different Asp concentrations were compared. Much lower Asp concentration was required to induce inactivation than to produce significant conformational changes of the enzyme molecule. However, with further addition of Asp, the molar ellipticity at 222 and 208 nm, the wavelength shift and the emission intensity of ANS hardly changed. Asp denatured AK was reactivated by dilution. In addition, potassium chloride (KCl) induced the molten globule state with a compact structure after AK was denatured with 7.5 mM Asp. These results collectively elucidate the osmotic effect of Asp anions for the molten globule formed during unfolding process. They also suggest that the effect of Asp differed from that of other denaturants such as guanidine hydrochloride or urea during AK folding. The molten globule state indicates that intermediates exist during AK folding.

Cloud cover and horizontal plane eye damaging solar UV exposures.

PubMed

Parisi, A V; Downs, N

2004-11-01

The spectral UV and the cloud cover were measured at intervals of 5 min with an integrated cloud and spectral UV measurement system at a sub-tropical Southern Hemisphere site for a 6-month period and solar zenith angle (SZA) range of 4.7 degrees to approximately 80 degrees . The solar UV spectra were recorded between 280 nm and 400 nm in 0.5 nm increments and weighted with the action spectra for photokeratitis and cataracts in order to investigate the effect of cloud cover on the horizontal plane biologically damaging UV irradiances for cataracts (UVBE(cat)) and photokeratitis (UVBE(pker)). Eighty five percent of the recorded spectra produced a measured irradiance to a cloud free irradiance ratio of 0.6 and higher while 76% produced a ratio of 0.8 and higher. Empirical non-linear expressions as a function of SZA have been developed for all sky conditions to allow the evaluation of the biologically damaging UV irradiances for photokeratitis and cataracts from a knowledge of the unweighted UV irradiances.

Timing, rates and spectra of human germline mutation.

PubMed

Rahbari, Raheleh; Wuster, Arthur; Lindsay, Sarah J; Hardwick, Robert J; Alexandrov, Ludmil B; Turki, Saeed Al; Dominiczak, Anna; Morris, Andrew; Porteous, David; Smith, Blair; Stratton, Michael R; Hurles, Matthew E

2016-02-01

Germline mutations are a driving force behind genome evolution and genetic disease. We investigated genome-wide mutation rates and spectra in multi-sibling families. The mutation rate increased with paternal age in all families, but the number of additional mutations per year differed by more than twofold between families. Meta-analysis of 6,570 mutations showed that germline methylation influences mutation rates. In contrast to somatic mutations, we found remarkable consistency in germline mutation spectra between the sexes and at different paternal ages. In parental germ line, 3.8% of mutations were mosaic, resulting in 1.3% of mutations being shared by siblings. The number of these shared mutations varied significantly between families. Our data suggest that the mutation rate per cell division is higher during both early embryogenesis and differentiation of primordial germ cells but is reduced substantially during post-pubertal spermatogenesis. These findings have important consequences for the recurrence risks of disorders caused by de novo mutations.

The 90-day report for SL4 experiment S019: UV stellar astronomy

NASA Technical Reports Server (NTRS)

1974-01-01

The use of Experiment S019 to obtain moderate dispersion stellar spectra extending down to 1300A with sufficient spectral resolution to permit the study of ultraviolet (UV) line spectra and of spectral energy distributions of early-type stars is studied. Data obtained from this experiment should be of sufficient accuracy to permit detailed physical analysis of individual stars and nebulae, but an even more basic consideration is the expectation of obtaining spectra of a sufficient number of stars so that a statistically meaningful survey may be made of the UV spectra of a wide variety of star types. These should include all luminosity classes of spectral types O, B and A, as well as peculiar stars such as Wolf-Rayet stars and Ap or Am stars. An attempt was also made to obtain, in the no-prism mode, low dispersion UV spectra in a number of Milky Way star fields and in nearby galaxies.

Large-mutation spectra induced at hemizygous loci by low-LET radiation: evidence for intrachromosomal proximity effects

NASA Technical Reports Server (NTRS)

Costes, S.; Sachs, R.; Hlatky, L.; Vannais, D.; Waldren, C.; Fouladi, B.; Chatterjee, A. (Principal Investigator)

2001-01-01

A mathematical model is used to analyze mutant spectra for large mutations induced by low-LET radiation. The model equations are based mainly on two-break misrejoining that leads to deletions or translocations. It is assumed, as a working hypothesis, that the initial damage induced by low-LET radiation is located randomly in the genome. Specifically, we analyzed data for two hemizygous loci: CD59- mutants, mainly very large-scale deletions (>3 Mbp), in human-hamster hybrid cells, and data from the literature on those HPRT- mutants which involve at least deletion of the whole gene, and often of additional flanking markers (approximately 50-kbp to approximately 4.4-Mbp deletions). For five data sets, we estimated f, the probability that two given breaks on the same chromosome will misrejoin to make a deletion, as a function of the separation between the breaks. We found that f is larger for nearby breaks than for breaks that are more widely separated; i.e., there is a "proximity effect". For acute irradiation, the values of f determined from the data are consistent with the corresponding break misrejoining parameters found previously in quantitative modeling of chromosome aberrations. The value of f was somewhat smaller for protracted irradiation than for acute irradiation at a given total dose; i.e., the mutation data show a decrease that was smaller than expected for dose protraction by fractionation or low dose rate.

A comparison of somatic mutational spectra in healthy study populations from Russia, Sweden and USA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noori, P; Hou, S; Jones, I M

Comparison of mutation spectra at the hypoxanthine-phosphoribosyl transferase (HPRT) gene of peripheral blood T lymphocytes may provide insight into the aetiology of somatic mutation contributing to carcinogenesis and other diseases. To increase knowledge of mutation spectra in healthy people, we have analyzed HPRT mutant T-cells of 50 healthy Russians originally recruited as controls for a study of Chernobyl clean-up workers (Jones et al. Radiation Res. 158, 2002, 424). Reverse transcriptase polymerase chain reactions and DNA sequencing identified 161 independent mutations among 176 thioguanine resistant mutants. Forty (40) mutations affected splicing mechanisms and 27 deletions or insertions of 1 to 60more » nucleotides were identified. Ninety four (94) single base substitutions were identified, including 62 different mutations at 55 different nucleotide positions, of which 19 had not previously been reported in human T-cells. Comparison of this base substitution spectrum with mutation spectra in a USA (Burkhart-Schultz et al. Carcinogenesis 17, 1996, 1871) and two Swedish populations (Podlutsky et al, Carcinogenesis 19, 1998, 557, Podlutsky et al. Mutation Res. 431, 1999, 325) revealed similarity in the type, frequency and distribution of mutations in the four spectra, consistent with aetiologies inherent in human metabolism. There were 15-19 identical mutations in the three pair-wise comparisons of Russian with USA and Swedish spectra. Intriguingly, there were 21 mutations unique to the Russian spectrum, and comparison by the Monte Carlo method of Adams and Skopek (J. Mol. Biol. 194, 1987, 391) indicated that the Russian spectrum was different from both Swedish spectra (P=0.007, 0.002) but not different from the USA spectrum (P=0.07), when Bonferroni correction for multiple comparisons was made (p < 0.008 required for significance). Age and smoking did not account for these differences. Other factors causing mutational differences need to be explored.« less

Hydrazine-induced post-chemiluminescence phenomenon of permanganate-luminol reaction and its applications.

PubMed

Du, Jianxiu; Lu, Jiuru

2004-01-01

The post-chemiluminescence phenomenon arising from the permanganate-luminol reaction induced by hydrazine and isoniazid was investigated. When hydrazine or isoniazid was injected into the mixture after the end of the reaction of permanganate with alkaline luminol, a new chemiluminescence (CL) reaction was initiated and strong CL signal was detected. A possible CL mechanism is suggested, based upon the studies of the kinetic characteristics of the CL reaction, the UV-visible spectra, the CL spectra and some other experiments. The present reactions allow the determination of 0.1-10.0 mg/L hydrazine and 0.02-1.0 mg/L isoniazid, with detection limits of 0.03 mg/L and 0.006 mg/L, respectively. The method was applied to the determination of isoniazid in pharmaceutical preparations.

Binding of anti-prion agents to glycosaminoglycans: Evidence from electronic absorption and circular dichroism spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zsila, Ferenc; Gedeon, Gabor

2006-08-11

The polyanionic glycosaminoglycans (GAGs) are intimately involved in the pathogenesis of protein conformational disorders such as amyloidosis and prion diseases. Several cationic agents are known to exhibit anti-prion activity but their mechanism of action is poorly understood. In this study, UV absorption and circular dichroism (CD) spectroscopic techniques were used to investigate the interaction between heparin and chondroitin-6-sulfate and anti-prion drugs including acridine, quinoline, and phenothiazine derivatives. UV band hypochromism of ({+-})-quinacrine, ({+-})-primaquine, tacrine, quinidine, chlorpromazine, and induced CD spectra of ({+-})-quinacrine upon addition of GAGs provided evidence for the GAG binding of these compounds. The association constants ({approx}10{sup 6}-10{supmore » 7} M{sup -1}) estimated from the UV titration curves show high-affinity drug-heparin interactions. Ionic strength-dependence of the absorption spectra suggested that the interaction between GAGs and the cationic drugs is principally electrostatic in nature. Drug binding differences of heparin and chondroitin-6-sulfate were attributed to their different negative charge density. These results call the attention to the alteration of GAG-prion/GAG-amyloid interactions by which these compounds might exert their anti-prion/anti-amyloidogenic activities.« less

Transient Fluorescence Spectroscopy and laser induced fluorescence lifetimes of terbium doped dipicolinic acid

NASA Astrophysics Data System (ADS)

Makoui, Anali

We have investigated the use of deep UV laser induced fluorescence for the sensitive detection and spectroscopic lifetime studies of terbium doped dipicolinic acid (DPA-Tb) and used this to study the optical characteristics of DPA which is a chemical surrounding most bacterial spores. Background absorption spectra, fluorescence spectra, and Excitation Emission Matrix (EEM) spectra were made of the DPA-Tb complex, using both fixed 266 nm wavelength and tunable (220 nm--280 nm) UV laser excitations. Of importance, the fluorescence lifetimes of the four main fluorescence peaks (488 nm, 543 nm, 581 nm, and 618 nm) of the DPA-Tb complex have been measured for the first time to our knowledge. The lifetimes of all the fluorescing lines have been measured as a function of DPA-Tb concentration, solvent pH, and solvent composition, including that for the weakest fluorescing line of DPA-Tb at 618 nm. In addition, a new spectroscopic lifetime measurement technique, which we call "Transient Fluorescence Spectroscopy", was developed. In this technique, a weak, quasi-CW, amplitude modulated UV laser (8.5 kHz) was used to measure the lifetimes of the fluorescence lines, and yields insight into energy transfer and excitation lifetimes within the system. This technique is especially useful when a high power laser is not either available or not suitable. In the latter case, this would be when a high power pulsed deep-UV laser could produce bleaching or destruction of the biological specimen. In addition, this technique simulated the excitation and fluorescence emission of the DPA-Tb using a 4-level energy model, and solved the dynamic transient rate equations to predict the temporal behavior of the DPA-Tb emitted fluorescence. Excellent agreement between the experiments and the simulation were found. This technique has the potential to provide a more accurate value for the fluorescence lifetime values. In addition, with the use of asymmetric excitation waveforms, the dynamic transient rate equation analysis may allow for detailed studies of selected transfer mechanisms in a wide range of other spectroscopic applications including rare-earth solid-state lasing materials and biological samples.

Far Ultraviolet Spectroscopy of Saturn's Icy Moon Rhea

NASA Astrophysics Data System (ADS)

Elowitz, Mark; Hendrix, Amanda; Mason, Nigel J.; Sivaraman, Bhalamurugan

2018-01-01

We present an analysis of spatially resolved, far-UV reflectance spectra of Saturn’s icy satellite Rhea, collected by the Cassini Ultraviolet Imaging Spectrograph (UVIS). In recent years ultraviolet spectroscopy has become an important tool for analysing the icy satellites of the outer solar system (1Hendrix & Hansen, 2008). Far-UV spectroscopy provides unique information about the molecular structure and electronic transitions of chemical species. Many molecules that are suspected to be present in the icy surfaces of moons in the outer solar system have broad absorption features due to electronic transitions that occur in the far-UV portion of the spectrum. The studies show that Rhea, like the other icy satellites of the Saturnian system are dominated by water-ice as evident by the 165-nm absorption edge, with minor UV absorbing contaminants. Far-UV spectra of several Saturnian icy satellites, including Rhea and Dione, show an unexplained weak absorption feature centered near 184 nm. To carry out the geochemical survey of Rhea’s surface, the UVIS observations are compared with vacuum-UV spectra of thin-ice samples measured in laboratory experiments. Thin film laboratory spectra of water-ice and other molecular compounds in the solid phase were collected at near-vacuum conditions and temperatures identical to those at the surface of Rhea. Comparison between the observed far-UV spectra of Rhea’s surface ice and modelled spectra based on laboratory absorption measurements of different non-water-ice compounds show that two possible chemical compounds could explain the 184-nm absorption feature. The two molecular compounds include simple chlorine molecules and hydrazine monohydrate. Attempts to explain the source(s) of these compounds on Rhea and the scientific implications of their possible discovery will be summarized.[1] Hendrix, A. R. & Hansen, C. J. (2008). Icarus, 193, pp. 323-333.

FE Line Diagnostics of Multiply Shocked Stellar Atmospheres: The Mira S. Carinae

NASA Technical Reports Server (NTRS)

Bookbinder, Jay

1997-01-01

Extensive LWP-HI spectra were obtained of the Mira S Car at a rapid time cadence as compared with the shock cycle time of S Car. These spectra were obtained in an attempt to understand the velocity structures in the shocked wind using the fluoresced iron lines. Data analysis of the IUE observations, which included the primary calibration of all of the IUE spectra obtained of S Car, was carried out. In addition, line identifications, flux calculations, background subtractions, and line profile analysis as a function of S Car's pulsational phase were performed. The database incorporated all line identifications as a function of pulsation phase for all IUE LWP-HI observations to date of S Car. At least 45 separate iron line features are identified in the S Car spectrum at one or more phases of the shock cycle, including those due to Fe II (UV 161) which is pumped by three different iron lines; Fe I(UV 44) which is pumped by the Mg II k line. Other strong multiplets that have been identified include UV(1), UV(2), UV(5), UV(32), UV(60), UV(63), UV(161), UV(207), and UV(399). Over 300 weaker lines have also been tentatively identified with Fe line transitions.

Photoionization of radiation-induced traps in quartz and alkali feldspars.

PubMed

Hütt, G; Jaek, I; Vasilchenko, V

2001-01-01

For the optimization of luminescence dating and dosimetry techniques on the basis of the optically stimulated luminescence, the stimulation spectra of quartz and alkali feldspars were measured in the spectral region of 250-1100 nm using optically stimulated afterglow. Optically stimulated luminescence in all studied spectral regions is induced by the same kind of deep traps, that produce thermoluminescence in the regions of palaeodosimetric peaks for both minerals. The mechanism for photoionization of deep traps was proposed as being due to delocalization of the excited state of the corresponding lattice defects. The excited state overlaps the zone states; i.e. is situated in the conduction band. Because of the high quantum yield of deep electron trap ionization in the UV spectral region, the present aim was to study the possibility of using UV-stimulation for palaeodose reconstruction.

[The role of remodeling complexes CHD1 and ISWI in spontaneous and UV-induced mutagenesis control in yeast Saccharomyces cerevisiae].

PubMed

Evstiukhina, T A; Alekseeva, E A; Fedorov, D V; Peshekhonov, V T; Korolev, V G

2017-02-01

Chromatin remodulators are special multiprotein machines capable of transforming the structure, constitution, and positioning of nucleosomes on DNA. Biochemical activities of remodeling complexes CHD1 and ISWI from the SWI2/SNF2 family are well established. They ensure correct positioning of nucleosomes along the genome, which is probably critical for genome stability, in particular, after action of polymerases, repair enzymes, and transcription. In this paper, we show that single mutations in genes ISW1, ISW2, and CHD1 weakly affect repair and mutagenic processes in yeast cells. At the same time, there are differences in the effect of these mutations on spontaneous mutation levels, which indicates certain specificity of action of protein complexes ISW1, ISW2, and CHD1 on expression of different genes that control repair and mutation processes in yeast.

COMPARATIVE MUTAGENICITY OF HALOMETHANES AND HALONITROMETHANES IN SALMONELLA TA100: STRUCTURE-ACTIVITY ANALYSIS AND MUTATION SPECTRA. (ERD)

EPA Science Inventory

Halonitromethanes (HNMs) are a recently identified class of disinfection by-products (DPBs) in drinking water that are mutagenic in Salmonella and potent inducers of DNA strand breaks in mammalian cells. Here we compared the mutagenic potencies of the HNMs to those of their halo...

COMPARATIVE MUTAGENICITY OF HALOMETHANES AND HALONITROMETHANES IN SALMONELLA TA100: STRUCTURE-ACTIVITY ANALYSIS AND MUTATION SPECTRA

EPA Science Inventory

Halonitromethanes (HNMs) are a recently identified class of disinfection by-products (DPBs) in drinking water that are mutagenic in Salmonella and potent inducers of DNA strand breaks in mammalian cells. Here we compared the mutagenic potencies of the HNMs to those of their halom...

Highly Sensitive Detection of UV Radiation Using a Uranium Coordination Polymer.

PubMed

Liu, Wei; Dai, Xing; Xie, Jian; Silver, Mark A; Zhang, Duo; Wang, Yanlong; Cai, Yawen; Diwu, Juan; Wang, Jian; Zhou, Ruhong; Chai, Zhifang; Wang, Shuao

2018-02-07

The accurate detection of UV radiation is required in a wide range of chemical industries and environmental or biological related applications. Conventional methods taking advantage of semiconductor photodetectors suffer from several drawbacks such as sophisticated synthesis and manufacturing procedure, not being able to measure the accumulated UV dosage as well as high defect density in the material. Searching for new strategies or materials serving as precise UV dosage sensor with extremely low detection limit is still highly desirable. In this work, a radiation resistant uranium coordination polymer [UO 2 (L)(DMF)] (L = 5-nitroisophthalic acid, DMF = N,N-dimethylformamide, denoted as compound 1) was successfully synthesized through mild solvothermal method and investigated as a unique UV probe with the detection limit of 2.4 × 10 -7 J. On the basis of the UV dosage dependent luminescence spectra, EPR analysis, single crystal structure investigation, and the DFT calculation, the UV-induced radical quenching mechanism was confirmed. Importantly, the generated radicals are of significant stability which offers the opportunity for measuring the accumulated UV radiation dosage. Furthermore, the powder material of compound 1 was further upgraded into membrane material without loss in luminescence intensity to investigate the real application potentials. To the best of our knowledge, compound 1 represents the most sensitive coordination polymer based UV dosage probe reported to date.

The Circadian Clock Controls Sunburn Apoptosis and Erythema in Mouse Skin

PubMed Central

Gaddameedhi, Shobhan; Selby, Christopher P.; Kemp, Michael G.; Ye, Rui; Sancar, Aziz

2014-01-01

Epidemiological studies of humans and experimental studies with mouse models suggest that sunburn resulting from exposure to excessive UV light and damage to DNA confers an increased risk for melanoma and non-melanoma skin cancer. Previous reports have shown that both nucleotide excision repair, which is the sole pathway in humans for removing UV photoproducts, and DNA replication, are regulated by the circadian clock in mouse skin. Furthermore, the timing of UV exposure during the circadian cycle has been shown to affect skin carcinogenesis in mice. Because sunburn and skin cancer are causally related, we investigated UV-induced sunburn apoptosis and erythema in mouse skin as a function of circadian time. Interestingly, we observed that sunburn apoptosis, inflammatory cytokine induction, and erythema were maximal following an acute early morning exposure to UV and minimal following an afternoon exposure. Early morning exposure to UV also produced maximal activation of Atr-mediated DNA damage checkpoint signaling including activation of the tumor suppressor p53, which is known to control the process of sunburn apoptosis. To our knowledge these data provide the first evidence that the circadian clock plays an important role in the erythemal response in UV-irradiated skin. The early morning is when DNA repair is at a minimum, thus the acute responses likely are associated with unrepaired DNA damage. The prior report that mice are more susceptible to skin cancer induction following chronic irradiation in the AM, when p53 levels are maximally induced, is discussed in terms of the mutational inactivation of p53 during chronic irradiation. PMID:25431853

Mutation-Induced Changes in the Protein Environment and Site Energies in the (M)L214G Mutant of the Rhodobacter sphaeroides Bacterial Reaction Center.

PubMed

Jankowiak, Ryszard; Rancova, Olga; Chen, Jinhai; Kell, Adam; Saer, Rafael G; Beatty, J Thomas; Abramavicius, Darius

2016-08-18

This work focuses on the low-temperature (5 K) photochemical (transient) hole-burned (HB) spectra within the P870 absorption band, and their theoretical analysis, for the (M)L214G mutant of the photosynthetic Rhodobacter sphaeroides bacterial reaction center (bRC). To provide insight into system-bath interactions of the bacteriochlorophyll a (BChl a) special pair, i.e., P870, in the mutated bRC, the optical line shape function for the P870 band is calculated numerically. On the basis of the modeling studies, we demonstrate that (M)L214G mutation leads to a heterogeneous population of bRCs with modified (increased) total electron-phonon coupling strength of the special pair BChl a and larger inhomogeneous broadening. Specifically, we show that after mutation in the (M)L214G bRC a large fraction (∼50%) of the bacteriopheophytin (HA) chromophores shifts red and the 800 nm absorption band broadens, while the remaining fraction of HA cofactors retains nearly the same site energy as HA in the wild-type bRC. Modeling using these two subpopulations allowed for fits of the absorption and nonresonant (transient) HB spectra of the mutant bRC in the charge neutral, oxidized, and charge-separated states using the Frenkel exciton Hamiltonian, providing new insight into the mutant's complex electronic structure. Although the average (M)L214G mutant quantum efficiency of P(+)QA(-) state formation seems to be altered in comparison with the wild-type bRC, the average electron transfer time (measured via resonant transient HB spectra within the P870 band) was not affected. Thus, mutation in the vicinity of the electron acceptor (HA) does not tune the charge separation dynamics. Finally, quenching of the (M)L214G mutant excited states by P(+) is addressed by persistent HB spectra burned within the B band in chemically oxidized samples.

A Simple Spreadsheet Program to Simulate and Analyze the Far-UV Circular Dichroism Spectra of Proteins

ERIC Educational Resources Information Center

Abriata, Luciano A.

2011-01-01

A simple algorithm was implemented in a spreadsheet program to simulate the circular dichroism spectra of proteins from their secondary structure content and to fit [alpha]-helix, [beta]-sheet, and random coil contents from experimental far-UV circular dichroism spectra. The physical basis of the method is briefly reviewed within the context of…

A shifting mutational landscape in 6 nutritional states: Stress-induced mutagenesis as a series of distinct stress input-mutation output relationships.

PubMed

Maharjan, Ram P; Ferenci, Thomas

2017-06-01

Environmental stresses increase genetic variation in bacteria, plants, and human cancer cells. The linkage between various environments and mutational outcomes has not been systematically investigated, however. Here, we established the influence of nutritional stresses commonly found in the biosphere (carbon, phosphate, nitrogen, oxygen, or iron limitation) on both the rate and spectrum of mutations in Escherichia coli. We found that each limitation was associated with a remarkably distinct mutational profile. Overall mutation rates were not always elevated, and nitrogen, iron, and oxygen limitation resulted in major spectral changes but no net increase in rate. Our results thus suggest that stress-induced mutagenesis is a diverse series of stress input-mutation output linkages that is distinct in every condition. Environment-specific spectra resulted in the differential emergence of traits needing particular mutations in these settings. Mutations requiring transpositions were highest under iron and oxygen limitation, whereas base-pair substitutions and indels were highest under phosphate limitation. The unexpected diversity of input-output effects explains some important phenomena in the mutational biases of evolving genomes. The prevalence of bacterial insertion sequence transpositions in the mammalian gut or in anaerobically stored cultures is due to environmentally determined mutation availability. Likewise, the much-discussed genomic bias towards transition base substitutions in evolving genomes can now be explained as an environment-specific output. Altogether, our conclusion is that environments influence genetic variation as well as selection.

A shifting mutational landscape in 6 nutritional states: Stress-induced mutagenesis as a series of distinct stress input–mutation output relationships

PubMed Central

Maharjan, Ram P.

2017-01-01

Environmental stresses increase genetic variation in bacteria, plants, and human cancer cells. The linkage between various environments and mutational outcomes has not been systematically investigated, however. Here, we established the influence of nutritional stresses commonly found in the biosphere (carbon, phosphate, nitrogen, oxygen, or iron limitation) on both the rate and spectrum of mutations in Escherichia coli. We found that each limitation was associated with a remarkably distinct mutational profile. Overall mutation rates were not always elevated, and nitrogen, iron, and oxygen limitation resulted in major spectral changes but no net increase in rate. Our results thus suggest that stress-induced mutagenesis is a diverse series of stress input–mutation output linkages that is distinct in every condition. Environment-specific spectra resulted in the differential emergence of traits needing particular mutations in these settings. Mutations requiring transpositions were highest under iron and oxygen limitation, whereas base-pair substitutions and indels were highest under phosphate limitation. The unexpected diversity of input–output effects explains some important phenomena in the mutational biases of evolving genomes. The prevalence of bacterial insertion sequence transpositions in the mammalian gut or in anaerobically stored cultures is due to environmentally determined mutation availability. Likewise, the much-discussed genomic bias towards transition base substitutions in evolving genomes can now be explained as an environment-specific output. Altogether, our conclusion is that environments influence genetic variation as well as selection. PMID:28594817

Flame Characterization Using a Tunable Solid-State Laser with Direct UV Pumping

NASA Technical Reports Server (NTRS)

Kamal, Mohammed M.; Dubinskii, Mark A.; Misra, Prabhakar

1996-01-01

Tunable solid-state lasers with direct UV pumping, based on d-f transitions of rare earth ions incorporated in wide band-gap dielectric crystals, are reliable sources of laser radiation that are suitable for excitation of combustion-related free radicals. We have employed such a laser for analytical flame characterization utilizing Laser-Induced Fluorescence (LIF) techniques. LIF spectra of alkane-air flames (used for studying combustion processes under normal and microgravity conditions) excited in the region of the A-X (0,0) OH-absorption band have been recorded and found to be both temperature-sensitive and positionally-sensitive. In addition, also clearly noticeable was the sensitivity of the spectra to the specific wavelength used for data registration. The LiCAF:Ce laser shows good prospects for being able to cover the spectral region between 280 and 340 nm and therefore be used excitation of combustion-intermediates such as the hydroxyl OH, methoxy CH30 and methylthio CH3S radicals.

Mutations in LZTR1 add to the complex heterogeneity of schwannomatosis.

PubMed

Smith, Miriam J; Isidor, Bertand; Beetz, Christian; Williams, Simon G; Bhaskar, Sanjeev S; Richer, Wilfrid; O'Sullivan, James; Anderson, Beverly; Daly, Sarah B; Urquhart, Jill E; Fryer, Alan; Rustad, Cecilie F; Mills, Samantha J; Samii, Amir; du Plessis, Daniel; Halliday, Dorothy; Barbarot, Sebastien; Bourdeaut, Franck; Newman, William G; Evans, D Gareth

2015-01-13

We aimed to determine the proportion of individuals in our schwannomatosis cohort whose disease is associated with an LZTR1 mutation. We used exome sequencing, Sanger sequencing, and copy number analysis to screen 65 unrelated individuals with schwannomatosis who were negative for a germline NF2 or SMARCB1 mutation. We also screened samples from 39 patients with a unilateral vestibular schwannoma (UVS), plus at least one other schwannoma, but who did not have an identifiable germline or mosaic NF2 mutation. We identified germline LZTR1 mutations in 6 of 16 patients (37.5%) with schwannomatosis who had at least one affected relative, 11 of 49 (22%) sporadic patients, and 2 of 39 patients with UVS in our cohort. Three germline mutation-positive patients in total had developed a UVS. Mosaicism was excluded in 3 patients without germline mutation in NF2, SMARCB1, or LZTR1 by mutation screening in 2 tumors from each. Our data confirm the relationship between mutations in LZTR1 and schwannomatosis. They indicate that germline mutations in LZTR1 confer an increased risk of vestibular schwannoma, providing further overlap with NF2, and that further causative genes for schwannomatosis remain to be identified. © 2014 American Academy of Neurology.

Laser induced fluorescence of biochemical for UV LIDAR application.

PubMed

Gupta, L; Sharma, R C; Razdan, A K; Maini, A K

2014-05-01

Laser induced fluorescence spectroscopy in the ultraviolet regime has been used for the detection of biochemical through a fiber coupled CCD detector from a distance of 2 m. The effect of concentration and laser excitation energy on the fluorescence spectra of nicotinamide adenine dinucleotide (NADH) has been investigated. The signature fluorescence peak of NADH was centred about 460 nm. At lower concentration Raman peak centred at 405 nm was also observed. The origin of this peak has been discussed. Detection limit with the proposed set up is found to be 1 ppm.

Photocarcinogenesis and Skin Cancer Prevention Strategies.

PubMed

Seebode, Christina; Lehmann, Janin; Emmert, Steffen

2016-03-01

In this review the basic principles of UV-induced carcinogenesis are summarized and the state of the art diagnosis and therapeutic strategies are discussed. The prevalent keratinocyte-derived neoplasms of the skin are basal cell and squamous cell carcinomas. Cutaneous melanoma is less frequent but associated with high mortality. Common risk factors for all three tumor entities include sun exposure and DNA-repair deficiencies. Photocarcinogenesis follows a multistep model of cancer development in which ultraviolet-induced DNA damage leads to mutations resulting in activation of oncogenes or silencing of tumor-suppressor genes. This ends in a cellular mutator phenotype even more prone to mutation acquisition. DNA repair, especially the nucleotide excision repair (NER) pathway, counteracts mutation formation and skin cancer development. This is vividly demonstrated by the NER-defective disorder xeroderma pigmentosum. Primary skin cancer preventative strategies, therefore, include reduction of DNA photodamage by protection from the sun. Secondary preventative strategies include skin cancer screening. This implies standard examination techniques with the naked eye, an epiluminescence microscope, or digital epiluminescence microscopy. More advanced techniques include confocal laser scan microscopy. Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

Comparing Ultraviolet Spectra Against Calculations: First Results

NASA Technical Reports Server (NTRS)

Peterson, Ruth C.

2003-01-01

The five-year goal of this effort is to calculate high fidelity mid-UV spectra for individual stars and stellar systems for a wide range of ages, abundances, and abundance ratios. In this first year, the emphasis was placed on revising the list of atomic line parameters used to calculate mid-UV spectra. First, new identifications of atomic lines and measurements of their transition probabilities were obtained for lines of the first and second ionization stages of iron-peak elements. Second, observed mid-UV and optical spectra for standard stars were re-analyzed and compared to new calculations, to refine the determination of transition probabilities and to estimate the identity of lines still missing from the laboratory lists. As evidenced by the figures, a dramatic improvement has resulted in the reproduction of the spectra of standard stars by the calculations.

Inducible DNA-repair systems in yeast: competition for lesions.

PubMed

Mitchel, R E; Morrison, D P

1987-03-01

DNA lesions may be recognized and repaired by more than one DNA-repair process. If two repair systems with different error frequencies have overlapping lesion specificity and one or both is inducible, the resulting variable competition for the lesions can change the biological consequences of these lesions. This concept was demonstrated by observing mutation in yeast cells (Saccharomyces cerevisiae) exposed to combinations of mutagens under conditions which influenced the induction of error-free recombinational repair or error-prone repair. Total mutation frequency was reduced in a manner proportional to the dose of 60Co-gamma- or 254 nm UV radiation delivered prior to or subsequent to an MNNG exposure. Suppression was greater per unit radiation dose in cells gamma-irradiated in O2 as compared to N2. A rad3 (excision-repair) mutant gave results similar to wild-type but mutation in a rad52 (rec-) mutant exposed to MNNG was not suppressed by radiation. Protein-synthesis inhibition with heat shock or cycloheximide indicated that it was the mutation due to MNNG and not that due to radiation which had changed. These results indicate that MNNG lesions are recognized by both the recombinational repair system and the inducible error-prone system, but that gamma-radiation induction of error-free recombinational repair resulted in increased competition for the lesions, thereby reducing mutation. Similarly, gamma-radiation exposure resulted in a radiation dose-dependent reduction in mutation due to MNU, EMS, ENU and 8-MOP + UVA, but no reduction in mutation due to MMS. These results suggest that the number of mutational MMS lesions recognizable by the recombinational repair system must be very small relative to those produced by the other agents. MNNG induction of the inducible error-prone systems however, did not alter mutation frequencies due to ENU or MMS exposure but, in contrast to radiation, increased the mutagenic effectiveness of EMS. These experiments demonstrate that in this lower eukaryote, mutagen exposure does not necessarily result in a fixed risk of mutation, but that the risk can be markedly influenced by a variety of external stimuli including heat shock or exposure to other mutagens.

Changes induced by UV radiation in the presence of sodium benzoate in films formulated with polyvinyl alcohol and carboxymethyl cellulose.

PubMed

Villarruel, S; Giannuzzi, L; Rivero, S; Pinotti, A

2015-11-01

This work was focused on: i) developing single and blend films based on carboxymethyl cellulose (CMC) and polyvinyl alcohol (PVOH) studying their properties, ii) analyzing the interactions between CMC and PVOH and their modifications UV-induced in the presence of sodium benzoate (SB), and iii) evaluating the antimicrobial capacity of blend films containing SB with and without UV treatment. Once the blend films with SB were exposed to UV radiation, they exhibited lower moisture content as well as a greater elongation at break and rougher surfaces compared to those without treatment. Considering oxygen barrier properties, the low values obtained would allow their application as packaging with selective oxygen permeability. Moreover, the characteristics of the amorphous phase of the matrix prevailed with a rearrangement of the structure of the polymer chain, causing a decrease of the crystallinity degree. These results were supported by X-rays and DSC analysis. FT-IR spectra reflected some degree of polymer-polymer interaction at a molecular level in the amorphous regions. The incorporation of sodium benzoate combined with UV treatment in blend films was positive from the microbial point of view because of the growth inhibition of a wide spectrum of microorganisms. From a physicochemical perspective, the UV treatment of films also changed their morphology rendering them more insoluble in water, turning the functionalized blend films into a potential material to be applied as food packaging. Copyright © 2015 Elsevier B.V. All rights reserved.

Observation of aggregation triggered by Resonance Energy Transfer (RET) induced intermolecular pairing force.

PubMed

Pan, Xiaoyong; Wang, Weizhi; Ke, Lin; Zhang, Nan

2017-07-20

In this report, we showed the existence of RET induced intermolecular pairing force by comparing their fluorescence behaviors under room illumination vs standing in dark area for either PFluAnt solution or PFluAnt&PFOBT mixture. Their prominent emission attenuation under room illumination brought out the critical role of photo, i.e. RET induced intermolecular pairing force in induction of polymer aggregation. Constant UV-Vis absorption and fluorescence spectra in terms of both peak shapes and maximum wavelengths implied no chemical decomposition was involved. Recoverable fluorescence intensity, fluorescence lifetime as well as NMR spectra further exclude photo induced decomposition. The controllable on/off state of RET induced intermolecular pairing force was verified by the masking effect of outside PFluAnt solution which function as filter to block the excitation of inside PFluAnt and thus off the RET induced intermolecular pairing force. Theoretical calculation suggest that magnitude of RET induced intermolecular pairing force is on the same scale as that of van der Waals interaction. Although the absolute magnitude of RET induced intermolecular pairing force was not tunable, its effect can be magnified by intentionally turn it "on", which was achieved by irradiance with 5 W desk lamp in this report.

SO2 in the middle atmosphere of Venus: IR measurements from Venera 15 and comparison to UV

NASA Technical Reports Server (NTRS)

Zasova, L. V.; Moroz, V. I.; Esposito, L. W.; Na, C. Y.

1992-01-01

Two sets of measurements of SO2 bands in the Venus spectra are presented and compared: IR spectra obtained on the USSR Venera 15 orbiter and UV spectra from the American Pioneer Venus orbiter and sounding rockets. The 40-mbar level was chosen as a reference level for comparison. The UV data are referred to this level. There are three SO2 bands in the infrared spectrum: at 519, 1150, and 1360 cm(exp -1). The levels of their formation in the atmosphere may differ significantly, by more than 10 km.

Photoinduced Effects in the ZnO Luminescence Spectra

NASA Astrophysics Data System (ADS)

Akopyan, I. Kh.; Labzovskaya, M. E.; Novikov, B. V.; Lisachenko, A. A.; Serov, A. Yu.; Filosofov, N. G.

2018-02-01

The effect of intense UV irradiation on the photoluminescence (PL) spectra of ZnO powders and nanocrystalline films obtained by atomic layer deposition (ALD) was investigated. At room temperature, the behavior of the spectra under continuous UV irradiation in multiple vacuum-atmosphere cycles was studied. The changes in the intensities of exciton radiation and radiation in the "green" band region, associated with the phenomena of oxygen photodesorption and photoadsorption, are discussed. In the temperature range of 5-300 K, the effect of strong UV irradiation on the near-edge luminescence spectrum of ZnO films was studied. The nature of a new line arising in the photoluminescence spectra of an irradiated film in the region of emission of bound excitons is discussed.

A damaged DNA binding protein 2 mutation disrupting interaction with proliferating-cell nuclear antigen affects DNA repair and confers proliferation advantage.

PubMed

Perucca, Paola; Mocchi, Roberto; Guardamagna, Isabella; Bassi, Elisabetta; Sommatis, Sabrina; Nardo, Tiziana; Prosperi, Ennio; Stivala, Lucia Anna; Cazzalini, Ornella

2018-06-01

In mammalian cells, Nucleotide Excision Repair (NER) plays a role in removing DNA damage induced by UV radiation. In Global Genome-NER subpathway, DDB2 protein forms a complex with DDB1 (UV-DDB), recognizing photolesions. During DNA repair, DDB2 interacts directly with PCNA through a conserved region in N-terminal tail and this interaction is important for DDB2 degradation. In this work, we sought to investigate the role of DDB2-PCNA association in DNA repair and cell proliferation after UV-induced DNA damage. To this end, stable clones expressing DDB2 Wt and DDB2 PCNA- were used. We have found that cells expressing a mutant DDB2 show inefficient photolesions removal, and a concomitant lack of binding to damaged DNA in vitro. Unexpected cellular behaviour after DNA damage, such as UV-resistance, increased cell growth and motility were found in DDB2 PCNA- stable cell clones, in which the most significant defects in cell cycle checkpoint were observed, suggesting a role in the new cellular phenotype. Based on these findings, we propose that DDB2-PCNA interaction may contribute to a correct DNA damage response for maintaining genome integrity. Copyright © 2018 Elsevier B.V. All rights reserved.

ERCC2/XPD Lys751Gln alter DNA repair efficiency of platinum-induced DNA damage through P53 pathway.

PubMed

Zhang, Guopei; Guan, Yangyang; Zhao, Yuejiao; van der Straaten, Tahar; Xiao, Sha; Xue, Ping; Zhu, Guolian; Liu, Qiufang; Cai, Yuan; Jin, Cuihong; Yang, Jinghua; Wu, Shengwen; Lu, Xiaobo

2017-02-01

Platinum-based treatment causes Pt-DNA adducts which lead to cell death. The platinum-induced DNA damage is recognized and repaired by the nucleotide excision repair (NER) system of which ERCC2/XPD is a critical enzyme. Single nucleotide polymorphisms in ERCC2/XPD have been found to be associated with platinum resistance. The aim of the present study was to investigate whether ERCC2/XPD Lys751Gln (rs13181) polymorphism is causally related to DNA repair capacity of platinum-induced DNA damage. First, cDNA clones expressing different genotypes of the polymorphism was transfected to an ERCC2/XPD defective CHO cell line (UV5). Second, all cells were treated with cisplatin. Cellular survival rate were investigated by MTT growth inhibition assay, DNA damage levels were investigated by comet assay and RAD51 staining. The distribution of cell cycle and the change of apoptosis rates were detected by a flow cytometric method (FCM). Finally, P53mRNA and phospho-P53 protein levels were further investigated in order to explore a possible explanation. As expected, there was a significantly increased in viability of UV5 ERCC2 (AA) as compared to UV5 ERCC2 (CC) after cisplatin treatment. The DNA damage level of UV5 ERCC2 (AA) was significant decreased compared to UV5 ERCC2 (CC) at 24 h of treatment. Mutation of ERCC2rs13181 AA to CC causes a prolonged S phase in cell cycle. UV5 ERCC2 (AA) alleviated the apoptosis compared to UV5 ERCC2 (CC) , meanwhile P53mRNA levels in UV ERCC2 (AA) was also lower when compared UV5 ERCC2 (CC) . It co-incides with a prolonged high expression of phospho-P53, which is relevant for cell cycle regulation, apoptosis, and the DNA damage response (DDR). We concluded that ERCC2/XPD rs13181 polymorphism is possibly related to the DNA repair capacity of platinum-induced DNA damage. This functional study provides some clues to clarify the relationship between cisplatin resistance and ERCC2/XPDrs13181 polymorphism. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Mutations in LZTR1 add to the complex heterogeneity of schwannomatosis

PubMed Central

Smith, Miriam J.; Isidor, Bertand; Beetz, Christian; Williams, Simon G.; Bhaskar, Sanjeev S.; Richer, Wilfrid; O'Sullivan, James; Anderson, Beverly; Daly, Sarah B.; Urquhart, Jill E.; Fryer, Alan; Rustad, Cecilie F.; Mills, Samantha J.; Samii, Amir; du Plessis, Daniel; Halliday, Dorothy; Barbarot, Sebastien; Bourdeaut, Franck

2015-01-01

Objectives: We aimed to determine the proportion of individuals in our schwannomatosis cohort whose disease is associated with an LZTR1 mutation. Methods: We used exome sequencing, Sanger sequencing, and copy number analysis to screen 65 unrelated individuals with schwannomatosis who were negative for a germline NF2 or SMARCB1 mutation. We also screened samples from 39 patients with a unilateral vestibular schwannoma (UVS), plus at least one other schwannoma, but who did not have an identifiable germline or mosaic NF2 mutation. Results: We identified germline LZTR1 mutations in 6 of 16 patients (37.5%) with schwannomatosis who had at least one affected relative, 11 of 49 (22%) sporadic patients, and 2 of 39 patients with UVS in our cohort. Three germline mutation–positive patients in total had developed a UVS. Mosaicism was excluded in 3 patients without germline mutation in NF2, SMARCB1, or LZTR1 by mutation screening in 2 tumors from each. Conclusions: Our data confirm the relationship between mutations in LZTR1 and schwannomatosis. They indicate that germline mutations in LZTR1 confer an increased risk of vestibular schwannoma, providing further overlap with NF2, and that further causative genes for schwannomatosis remain to be identified. PMID:25480913

Fluorimetric detection of Sn(2+) ion in aqueous medium using Salicylaldehyde based nanoparticles and application to natural samples analysis.

PubMed

Patil, Kishor S; Mahajan, Prasad G; Patil, Shivajirao R

2017-01-05

The fluorescent 2-[(E)-(2-phenylhydrazinylidene)methyl]phenol nanoparticles (PHPNPs) were prepared by a simple reprecipitation method. The prepared PHPNPs examined by Dynamic Light Scattering show narrower particle size distribution having an average particle size of 93.3nm. The Scanning Electron Microphotograph shows distinct spherical shaped morphology of nanoparticles. The blue shift in UV-absorption and fluorescence spectra of PHPNPs with respect to corresponding spectra of PHP in acetone solution indicates H- aggregates and Aggregation Induced Enhanced Emission (AIEE) for nanoparticles. The nanoparticles show selective tendency towards the recognition of Sn(2+) ions by enhancing the fluorescence intensity preference to Cu(2+), Fe(3+), Fe(2+), Ni(2+), NH4(+), Ca(2+), Pb(2+), Hg(2+) and Zn(2+) ions, which actually seem to quench the fluorescence of nanoparticles. The studies on Langmuir adsorption plot, fluorescence lifetime of PHPNPs, DLS-Zeta sizer, UV-visible and fluorescence titration with and without Sn(2+) helped to propose a suitable mechanism of fluorescence enhancement of nanoparticles by Sn(2+) and their binding ability during complexation. The fluorescence enhancement effect of PHPNPs induced by Sn(2+) is further used to develop an analytical method for detection of Sn(2+) from aqueous medium in environmental samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Fluorimetric detection of Sn2 + ion in aqueous medium using Salicylaldehyde based nanoparticles and application to natural samples analysis

NASA Astrophysics Data System (ADS)

Patil, Kishor S.; Mahajan, Prasad G.; Patil, Shivajirao R.

2017-01-01

The fluorescent 2-[(E)-(2-phenylhydrazinylidene)methyl]phenol nanoparticles (PHPNPs) were prepared by a simple reprecipitation method. The prepared PHPNPs examined by Dynamic Light Scattering show narrower particle size distribution having an average particle size of 93.3 nm. The Scanning Electron Microphotograph shows distinct spherical shaped morphology of nanoparticles. The blue shift in UV-absorption and fluorescence spectra of PHPNPs with respect to corresponding spectra of PHP in acetone solution indicates H- aggregates and Aggregation Induced Enhanced Emission (AIEE) for nanoparticles. The nanoparticles show selective tendency towards the recognition of Sn2 + ions by enhancing the fluorescence intensity preference to Cu2 +, Fe3 +, Fe2 +, Ni2 +, NH4+, Ca2 +, Pb2 +, Hg2 + and Zn2 + ions, which actually seem to quench the fluorescence of nanoparticles. The studies on Langmuir adsorption plot, fluorescence lifetime of PHPNPs, DLS-Zeta sizer, UV-visible and fluorescence titration with and without Sn2 + helped to propose a suitable mechanism of fluorescence enhancement of nanoparticles by Sn2 + and their binding ability during complexation. The fluorescence enhancement effect of PHPNPs induced by Sn2 + is further used to develop an analytical method for detection of Sn2 + from aqueous medium in environmental samples.

Spectral measurements of alpha-induced radioluminescence in various gases

NASA Astrophysics Data System (ADS)

Brett, Jaclyn; Koehler, Katrina E.; Bischak, Michael; Famiano, Michael; Jenkins, Jared; Klankowski, Levi; Niraula, Prashantamani; Pancella, Paul; Lakis, Rollin

2017-12-01

Radioluminescent emission in Ar, N2, O2, and dry air at P = 1 atm was observed induced by 5 MeV α particles. The wavelength range with a single detector spanned 250-1100 nm, extending the range well into the UV and IR bands with a single detector. Measured spectral lines for alpha-induced luminescence were corrected for detector transmission and intensities compared to previous work. The exploration of multiple gases over a wide frequency range opens the door to security and remote sensing applications, where different environments are routinely encountered. This work provides spectra that can be used in guiding future filter development focusing on remote alpha detection.

The photocatalytic investigation of methylene blue dye with Cr doped zinc oxide nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ray, Rajeev; Kumar, Ashavani, E-mail: ashavani@yahoo.com

2015-08-28

The present work reports eco-friendly and cost effective sol-gel technique for synthesis of Chromium doped ZnO nanoparticles at room temperature. In this process Zinc nitrate, Chromium nitrate were used as precursor. Structural as well as optical properties of Cr induced ZnO samples were analysed by X-ray diffraction technique (XRD), SEM, PL and UV-Visible spectroscopy (UV-Vis) respectively. XRD analysis shows that the samples have hexagonal (wurtzite) structure with no additional peak which suggests that Cr ions fit into the regular Zn sites of ZnO crystal structure. By using Scherrer’s formula for pure and Cr doped ZnO samples the average grain sizemore » was found to be 32 nm. Further band gap of pure and doped ZnO samples have been calculated by using UV-Vis spectra. The photo-catalytic degradation of methyl blue dye under UV irradiation was examined for synthesized samples. The results show that the concentration plays an important role in photo-catalytic activity.« less

Frameshift Suppression in SACCHAROMYCES CEREVISIAE. III. Isolation and Genetic Properties of Group III Suppressors

PubMed Central

Cummins, Claudia M.; Gaber, Richard F.; Culbertson, Michael R.; Mann, Richard; Fink, Gerald R.

1980-01-01

Suppressors of ICR-induced mutations that exhibit behavior similar to bacterial frameshift suppressors have been identified in the yeast Saccharomyces cerevisiae. The yeast suppressors have been divided into two groups. Previous evidence indicated that suppressors of one group (Group II: SUF1, SUF3, SUF4, SUF5 and SUF6) represent mutations in the structural genes for glycyl-tRNA's. Suppressors of the other group (Group III: SUF2 and SUF7) were less well characterized. Although they suppressed some ICR-revertible mutations, they failed to suppress Group II frameshift mutations. This communication provides a more thorough characterization of the Group III suppressors and describes the isolation and properties of four new suppressors in that group (SUF8, SUF9, SUF10 and suf11).——In our original study, Group III suppressors were isolated as revertants of the Group III mutations his4–712 and his4–713. All suppressors obtained as ICR-induced revertants of these mutations mapped at the SUF2 locus near the centromere of chromosome III. Suppressors mapping at other loci were obtained in this study by analyzing spontaneous and UV-induced revertants of the Group III mutations. SUF2 and SUF10 suppress both Group III his4 mutations, whereas SUF7, SUF8, SUF9 and suf11 suppress his4–713, but not his4–712. All of the suppressors except suf11 are dominant in diploids homozygous for his4-713. The suppressors fail to suppress representative UAA, UAG and UGA nonsense mutations.——SUF9 is linked to the centromere of chromosome VI, and SUF10 is linked to the centromere of chromosome XIV. A triploid mapping procedure was used to determine the chromosome locations of SUF7 and SUF8. Subsequent standard crosses revealed linkage of SUF7 to cdc5 on chromosome XIII and linkage of SUF8 to cdc12 and pet3 on chromosome VIII. PMID:7009319

FIRST ULTRAVIOLET REFLECTANCE SPECTRA OF PLUTO AND CHARON BY THE HUBBLE SPACE TELESCOPE COSMIC ORIGINS SPECTROGRAPH: DETECTION OF ABSORPTION FEATURES AND EVIDENCE FOR TEMPORAL CHANGE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stern, S. A.; Spencer, J. R.; Shinn, A.

We have observed the mid-UV spectra of both Pluto and its large satellite, Charon, at two rotational epochs using the Hubble Space Telescope (HST) Cosmic Origins Spectrograph (COS) in 2010. These are the first HST/COS measurements of Pluto and Charon. Here we describe the observations and our reduction of them, and present the albedo spectra, average mid-UV albedos, and albedo slopes we derive from these data. These data reveal evidence for a strong absorption feature in the mid-UV spectrum of Pluto; evidence for temporal change in Pluto's spectrum since the 1990s is reported, and indirect evidence for a near-UV spectralmore » absorption on Charon is also reported.« less

Observations of normal main-sequence and giant B stars

NASA Astrophysics Data System (ADS)

When interpreting the continuous and line spectra of B stars, it is helpful to think in terms of a model consisting of a photosphere and a mantle which is the outer part of the atmosphere where the effects of nonradiative heating are seen. A survey of the spectra of these stars shows that conditions in the photosphere determine most of what is seen, and in the case of most B stars, the presence of the mantle can be detected only by a special effort. The shape of the visible continuum spectrum and the shape and absolute value of the UV continuous spectrum as determined from low resolution spectra are discussed. Effective temperature for B stars in the main sequence, including corrections for interstellar extinction and bolometric corrections are explored. The major constituents of B-type spectra, variation of the strength of line along the main sequence band, the UV spectra, UV line blocking, intrinsic colors, and variations in light and spectra are also examined.

Effects of temperature and SDS on the structure of beta-glycosidase from the thermophilic archaeon Sulfolobus solfataricus.

PubMed Central

D'auria, S; Barone, R; Rossi, M; Nucci, R; Barone, G; Fessas, D; Bertoli, E; Tanfani, F

1997-01-01

The effects of temperature and SDS on the three-dimensional organization and secondary structure of beta-glycosidase from the thermophilic archaeon Sulfolobus solfataricus were investigated by CD, IR spectroscopy and differential scanning calorimetry. CD spectra in the near UV region showed that the detergent caused a remarkable change in the protein tertiary structure, and far-UV CD analysis revealed only a slight effect on secondary structure. Infrared spectroscopy showed that low concentrations of the detergent (up to 0.02%) induced slight changes in the enzyme secondary structure, whereas high concentrations caused the alpha-helix content to increase at high temperatures and prevented protein aggregation. PMID:9169619

SASH1 regulates melanocyte transepithelial migration through a novel Gαs-SASH1-IQGAP1-E-Cadherin dependent pathway.

PubMed

Zhou, Ding'an; Wei, Zhiyun; Deng, Shanshan; Wang, Teng; Zai, Meiqing; Wang, Honglian; Guo, Luo; Zhang, Junyu; Zhong, Hailei; He, Lin; Xing, Qinghe

2013-06-01

One important function of melanocytes (MCs) is to produce and transfer melanin to neighbouring keratinocytes (KCs) to protect epithelial cells from UV radiation. The mechanisms regulating the specific migration and localisation of the MC lineage remain unknown. We have found three heterozygous mutations that cause amino acid substitutions in the SASH1 gene in individuals with a kind of dyschromatosis. In epidermal tissues from an affected individual, we observed the increased transepithelial migration of melanocytes. Functional analyses indicate that these SASH1 mutations not only cause the increased migration of A375 cells and but also induce intensive bindings with two novel cell adhesion partners IQGAP1 and Gαs. Further, SASH1 mutations induce uniform loss of E-Cadherin in human A375 cells. Our findings suggest a new scaffold protein SASH1 to regulate IQGAP1-E-Cadherin signalling and demonstrate a novel crosstalking between GPCR signalling, calmodulin signalling for the modulation of MCs invasion. Copyright © 2013 Elsevier Inc. All rights reserved.

Reusable hydroxyapatite nanocrystal sensors for protein adsorption.

PubMed

Tagaya, Motohiro; Ikoma, Toshiyuki; Hanagata, Nobutaka; Chakarov, Dinko; Kasemo, Bengt; Tanaka, Junzo

2010-08-01

The repeatability of the adsorption and removal of fibrinogen and fetal bovine serum on hydroxyapatite (HAp) nanocrystal sensors was investigated by Fourier transform infrared (FTIR) spectroscopy and quartz crystal microbalance with dissipation (QCM-D) monitoring technique. The HAp nanocrystals were coated on a gold-coated quartz sensor by electrophoretic deposition. Proteins adsorbed on the HAp sensors were removed by (i) ammonia/hydrogen peroxide mixture (APM), (ii) ultraviolet light (UV), (iii) UV/APM, (iv) APM/UV and (v) sodium dodecyl sulfate (SDS) treatments. FTIR spectra of the reused surfaces revealed that the APM and SDS treatments left peptide fragments or the proteins adsorbed on the surfaces, whereas the other methods successfully removed the proteins. The QCM-D measurements indicated that in the removal treatments, fibrinogen was slowly adsorbed in the first cycle because of the change in surface wettability revealed by contact angle measurements. The SDS treatment was not effective in removing proteins. The APM or UV treatment decreased the frequency shifts for the reused HAp sensors. The UV/APM treatment did not induce the frequency shifts but decreased the dissipation shifts. Therefore, we conclude that the APM/UV treatment is the most useful method for reproducing protein adsorption behavior on HAp sensors.

Reusable hydroxyapatite nanocrystal sensors for protein adsorption

NASA Astrophysics Data System (ADS)

Tagaya, Motohiro; Ikoma, Toshiyuki; Hanagata, Nobutaka; Chakarov, Dinko; Kasemo, Bengt; Tanaka, Junzo

2010-08-01

The repeatability of the adsorption and removal of fibrinogen and fetal bovine serum on hydroxyapatite (HAp) nanocrystal sensors was investigated by Fourier transform infrared (FTIR) spectroscopy and quartz crystal microbalance with dissipation (QCM-D) monitoring technique. The HAp nanocrystals were coated on a gold-coated quartz sensor by electrophoretic deposition. Proteins adsorbed on the HAp sensors were removed by (i) ammonia/hydrogen peroxide mixture (APM), (ii) ultraviolet light (UV), (iii) UV/APM, (iv) APM/UV and (v) sodium dodecyl sulfate (SDS) treatments. FTIR spectra of the reused surfaces revealed that the APM and SDS treatments left peptide fragments or the proteins adsorbed on the surfaces, whereas the other methods successfully removed the proteins. The QCM-D measurements indicated that in the removal treatments, fibrinogen was slowly adsorbed in the first cycle because of the change in surface wettability revealed by contact angle measurements. The SDS treatment was not effective in removing proteins. The APM or UV treatment decreased the frequency shifts for the reused HAp sensors. The UV/APM treatment did not induce the frequency shifts but decreased the dissipation shifts. Therefore, we conclude that the APM/UV treatment is the most useful method for reproducing protein adsorption behavior on HAp sensors.

UV irradiation study of a tripeptide isolated in an argon matrix: A tautomerism process evidenced by infrared and X-ray photoemission spectroscopies

NASA Astrophysics Data System (ADS)

Mateo-Marti, E.; Pradier, C. M.

2013-05-01

Matrix isolation is a powerful tool for studying photochemical processes occurring in isolated molecules. In this way, we characterized the chemical modifications occurring within a tri peptide molecule, IGF, when exposed to the influence of Ultraviolet (UV) irradiation. This paper first describes the successful formation of the tripeptide (IGF) argon matrix under vacuum conditions, followed by the in situ UV irradiation and characterization of the molecular matrix reactivity after UV-irradiation. These studies have been performed by combining two complementary spectroscopic techniques, Fourier-Transform Reflexion Absorption Spectroscopy (FT-IRRAS) and X-ray Photoelectron Spectroscopy (XPS). The IR spectra of the isolated peptide-matrix, before and after UV irradiation, revealed significant differences that could be associated either to a partial deprotonation of the molecule or to a tautomeric conversion of some amide bonds to imide ones on some peptide molecules. XPS analyses undoubtedly confirmed the second hypothesis; the combination of IRRAS and XPS results provide evidence that UV irradiation of peptides induces a chemical reaction, namely a shift of the double bond, meaning partial conversion from amide tautomer into an imidic acid tautomer.

Predicting the Shifts of Absorption Maxima of Azulene Derivatives Using Molecular Modeling and ZINDO CI Calculations of UV-Vis Spectra

ERIC Educational Resources Information Center

Patalinghug, Wyona C.; Chang, Maharlika; Solis, Joanne

2007-01-01

The deep blue color of azulene is drastically changed by the addition of substituents such as CH[subscript 3], F, or CHO. Computational semiempirical methods using ZINDO CI are used to model azulene and azulene derivatives and to calculate their UV-vis spectra. The calculated spectra are used to show the trends in absorption band shifts upon…

The application of BTEM to UV-vis and UV-vis CD spectroscopies: the reaction of Rh4(CO)12 with chiral and achiral ligands.

PubMed

Cheng, Shuying; Gao, Feng; Krummel, Karl I; Garland, Marc

2008-02-15

Two different organometallic ligand substitution reactions were investigated: (1) an achiral reactive system consisting of Rh(4)(CO)(12)+PPh(3)right harpoon over left harpoonRh(4)(CO)(11)PPh(3)+CO in n-hexane under argon; and (2) a chiral reactive system consisting of Rh(4)(CO)(12)+(S)-BINAPright harpoon over left harpoonRh(4)(CO)(10)BINAP+2CO in cyclohexane under argon. These two reactions were run at ultra high dilution. In both multi-component reactive systems the concentrations of all the solutes were less than 40ppm and many solute concentrations were just 1-10ppm. In situ spectroscopic measurements were carried out using UV-vis (Ultraviolet-visible) spectroscopy and UV-vis CD spectroscopy on the reactive organometallic systems (1) and (2), respectively. The BTEM algorithm was applied to these spectroscopic data sets. The reconstructed UV-vis pure component spectra of Rh(4)(CO)(12), Rh(4)(CO)(11)PPh(3) and Rh(4)(CO)(10)BINAP as well as the reconstructed UV-vis CD pure component spectra of Rh(4)(CO)(10)BINAP were successfully obtained from BTEM analyses. All these reconstructed pure component spectra are in good agreement with the experimental reference spectra. The concentration profiles of the present species were obtained by performing a least square fit with mass balance constraints for the reactions (1) and (2). The present results indicate that UV-vis and UV-vis-CD spectroscopies can be successfully combined with an appropriate chemometric technique in order to monitor reactive organometallic systems having UV and Vis chromophores.

Rutherford Backscattering Spectrometry studies of 100 keV nitrogen ion implanted polypropylene polymer

NASA Astrophysics Data System (ADS)

Chawla, Mahak; Aggarwal, Sanjeev; Sharma, Annu

2017-09-01

The effect of nitrogen ion implantation on the structure and composition in polypropylene (PP) polymer has been studied. Implantation was carried out using 100 keV N+ ions at different fluences of 1 × 1015, 1 × 1016 and 1 × 1017 ions cm-2 with beam current density of ∼0.65 μA cm-2. Surface morphological changes in the pre- and post-implanted PP specimens have been studied using Rutherford Backscattering Spectrometry (RBS) and UV-Visible Spectroscopy. The spatial distribution of implantation induced modification in the form of carbonization and dehydrogenation in the near surface region of PP matrix, the projected range, retained dose of implanted nitrogen, the various elements present in the implanted layers and their differential cross-sections have been analyzed using RBS spectra. RUMP simulation yielded an increase in the concentration of carbon near the surface from 33 at.% (virgin) to 42 at.% at fluence of 1 × 1017 N+ cm-2. Further, optical absorption has been found to increase with a shift in the absorption edge from UV towards visible region with increasing fluence. UV-Vis absorption spectra also indicate a drastic decrease in optical energy gap from 4.12 eV (virgin) to 0.25 eV (1 × 1017 N+ cm-2) indicating towards the formation of carbonaceous network in the implanted region. All these changes observed using UV-Visible have been further correlated with the outcomes of the RBS characterization.

Thermoresistant revertants of an Escherichia coli strain carrying tif-1 and ruv mutations: non-suppressibility of ruv by sfi.

PubMed Central

Otsuji, N; Iyehara-Ogawa, H

1979-01-01

Spontaneous thermoresistant revertants were isolated from Tif1 Ruv- and Tif1 Ruv+ strains of Escherichia coli K-12. They were divided into five groups; backmutants to tif+ and recA structural gene mutants accounted for at least two of these groups. Mutations with an unconditional RecA- phenyotype were detected at a higher frequency in the Tif1 Ruv- strains (65%) than in the Tif1 Ruv+ strains (25%). A third group consisted of revertants exhibiting a RecA- phenotype at low temperature. Revertants with normal recombination ability and UV resistance, but with a thermosensitive defect in propagating lambda bio11 phage, were also isolated (group 4). The alleles responsible for this property were cotransducible with the srl gene, suggesting that they are located at the recA locus. Other revertants, which might carry lex, LEXB, or zab mutations, were UV sensitive and were able to propagate lambda bio11 phage (group 5). The sfi mutation, which suppresses filamentation in the Tif1 and UV-sensitive Lon- strains, does not restore UV resistance of the Ruv- mutant. PMID:374356

Tissue-specific mutation accumulation in human adult stem cells during life

NASA Astrophysics Data System (ADS)

Blokzijl, Francis; de Ligt, Joep; Jager, Myrthe; Sasselli, Valentina; Roerink, Sophie; Sasaki, Nobuo; Huch, Meritxell; Boymans, Sander; Kuijk, Ewart; Prins, Pjotr; Nijman, Isaac J.; Martincorena, Inigo; Mokry, Michal; Wiegerinck, Caroline L.; Middendorp, Sabine; Sato, Toshiro; Schwank, Gerald; Nieuwenhuis, Edward E. S.; Verstegen, Monique M. A.; van der Laan, Luc J. W.; de Jonge, Jeroen; Ijzermans, Jan N. M.; Vries, Robert G.; van de Wetering, Marc; Stratton, Michael R.; Clevers, Hans; Cuppen, Edwin; van Boxtel, Ruben

2016-10-01

The gradual accumulation of genetic mutations in human adult stem cells (ASCs) during life is associated with various age-related diseases, including cancer. Extreme variation in cancer risk across tissues was recently proposed to depend on the lifetime number of ASC divisions, owing to unavoidable random mutations that arise during DNA replication. However, the rates and patterns of mutations in normal ASCs remain unknown. Here we determine genome-wide mutation patterns in ASCs of the small intestine, colon and liver of human donors with ages ranging from 3 to 87 years by sequencing clonal organoid cultures derived from primary multipotent cells. Our results show that mutations accumulate steadily over time in all of the assessed tissue types, at a rate of approximately 40 novel mutations per year, despite the large variation in cancer incidence among these tissues. Liver ASCs, however, have different mutation spectra compared to those of the colon and small intestine. Mutational signature analysis reveals that this difference can be attributed to spontaneous deamination of methylated cytosine residues in the colon and small intestine, probably reflecting their high ASC division rate. In liver, a signature with an as-yet-unknown underlying mechanism is predominant. Mutation spectra of driver genes in cancer show high similarity to the tissue-specific ASC mutation spectra, suggesting that intrinsic mutational processes in ASCs can initiate tumorigenesis. Notably, the inter-individual variation in mutation rate and spectra are low, suggesting tissue-specific activity of common mutational processes throughout life.

Cryogenic Laboratory Experiments into Radiation Effects on the Spectra of Non-Ice Materials relevant to Ocean Worlds

NASA Astrophysics Data System (ADS)

Cahill, K. R. S.; Hibbitts, C.; Wing, B. R.

2017-12-01

The airless satellites of Jupiter and Saturn are bombarded by high-energy particles from solar wind and their planetary magnetospheres. The particles range up to MeV energies and penetrate sufficiently far (microns) into the surface to cause damage that can affect their UV - IR spectral signatures. These particles physically and chemically alter the exposed surface by damaging crystallinity, sputtering non-refractory neutrals, depositing into the material, and inducing chemical reactions between existing and/or exogenous components. Previous studies of salts irradiated at room temperature ( 293 K) under high vacuum (1e-7 Torr) demonstrated the formation of radiation-induced color centers, or Farbe-centers, that are active at near UV, visible, and near IR wavelengths [1,2]. In this study, we investigated the effects of irradiation on these and other materials at temperatures relevant to the surfaces of the Galilean and Saturnian satellites. Experiments at the appropriate temperatures are important because the diffusion of the H-centers, which can interact with F-centers [3], are strongly temperature dependent and may be inhibited. This could affect the spectral signature of the irradiated materials. The experiments simulated the radiation environment using 40 keV electrons at 80 microamps under high vacuum at 100 K while characterizing the spectral changes (UV through mid-IR). Spectral measurements were obtained in the UV-Visible ( 130-570 nm) using a McPherson monochromater and photomultiplier detector, in the Visible-SWIR ( 340-2500 nm) using a SVC point spectrometer, and in the NIR-MIR ( 1500 to 8000 nm) using a Bruker Vertex 70 FTIR coupled to a liquid nitrogen cooled MCT detector. Spectra were collected while the sample was held under high vacuum at cryogenic temperatures both before, during, and after irradiation. Our results characterize the spectral signature of radiation-induced color centers that can form at the temperatures present at the surface of airless ocean worlds. We will show the spectral change induced by irradiation at cryogenic temperatures and compare these results to performed at room temperature. [1] Hibbitts et al. [2017], Icarus, submitted. [2] Hand and Carlson. [2015], GRL, 42, 3174-3178. [3] Soppe et al. [1994] J. Nuc. Mat., 217, 1-31.

Ultraviolet-B phototoxicity and hypothetical photomelanomagenesis: intraocular and crystalline lens photoprotection.

PubMed

Mainster, Martin A; Turner, Patricia L

2010-04-01

Ultraviolet-B (UV-B) radiation can cause phototoxic macular injuries in young people who have been sunbathing but not sungazing and in welders. Welders have a reportedly increased risk of uveal melanoma. We analyze phakic and pseudophakic risks for solar and welding arc UV-B exposure. Optical radiation measurement, analysis, and perspective. Spectral transmittances were measured for UV-transmitting, UV-blocking, and blue-blocking intraocular lenses (IOLs). The photoprotective performances of crystalline and intraocular lenses were analyzed using relevant epidemiologic and laboratory data and action spectra for acute retinal phototoxicity and melanoma photocarcinogenesis. Crystalline lens UV-B retinal protection is deficient in children and young adults, increasing their potential susceptibility to acute retinal phototoxicity and hypothetical photomelanomagenesis. UV-B radiation has sufficient energy/photon to induce primary melanomagenic DNA lesions, unlike blue light or UV-A radiation. UV-blocking and blue-blocking IOLs have negligible UV-B transmittance. UV-transmitting IOL transmittance of UV-B radiation is equivalent to that of a 15-year-old crystalline lens. If optical radiation exposure is responsible for welders' increased risk of uveal melanoma, then UV-B radiation is the most probable causative agent and spectacle wear is a potential confounding factor in epidemiologic studies of ocular melanoma. Welders under 30 years of age are at greater risk for welding maculopathy than older welders. Children, adults under 30 years of age, and pseudophakic individuals with UV-transmitting IOLs should wear sunglasses in bright environments because of the UV-B window in their crystalline lenses or IOLs. Copyright 2010 Elsevier Inc. All rights reserved.

Importance of Vibronic Effects in the UV-Vis Spectrum of the 7,7,8,8-Tetracyanoquinodimethane Anion.

PubMed

Tapavicza, Enrico; Furche, Filipp; Sundholm, Dage

2016-10-11

We present a computational method for simulating vibronic absorption spectra in the ultraviolet-visible (UV-vis) range and apply it to the 7,7,8,8-tetracyanoquinodimethane anion (TCNQ - ), which has been used as a ligand in black absorbers. Gaussian broadening of vertical electronic excitation energies of TCNQ - from linear-response time-dependent density functional theory produces only one band, which is qualitatively incorrect. Thus, the harmonic vibrational modes of the two lowest doublet states were computed, and the vibronic UV-vis spectrum was simulated using the displaced harmonic oscillator approximation, the frequency-shifted harmonic oscillator approximation, and the full Duschinsky formalism. An efficient real-time generating function method was implemented to avoid the exponential complexity of conventional Franck-Condon approaches to vibronic spectra. The obtained UV-vis spectra for TCNQ - agree well with experiment; the Duschinsky rotation is found to have only a minor effect on the spectrum. Born-Oppenheimer molecular dynamics simulations combined with calculations of the electronic excitation energies for a large number of molecular structures were also used for simulating the UV-vis spectrum. The Born-Oppenheimer molecular dynamics simulations yield a broadening of the energetically lowest peak in the absorption spectrum, but additional vibrational bands present in the experimental and simulated quantum harmonic oscillator spectra are not observed in the molecular dynamics simulations. Our results underline the importance of vibronic effects for the UV-vis spectrum of TCNQ - , and they establish an efficient method for obtaining vibronic spectra using a combination of linear-response time-dependent density functional theory and a real-time generating function approach.

Fabrication of Ta nanoparticles induced by nanosecond laser ablation in ethanol: the study of laser fluence effects

NASA Astrophysics Data System (ADS)

Azadi Kenari, Fariba; Moniri, Samira; Hantehzadeh, Mohammad Reza; Dorranian, Davoud; Ghoranneviss, Mahmood

2018-05-01

Tantalum nanoparticles (Ta NPs) were synthesized in ethanol solution by ablation with a 1064 nm Nd:YAG laser. Prepared NPs were investigated by UV-visible absorption spectroscopy, Transmission electron microscopy, X-ray diffraction and Photoluminescence measurement. The average sizes of NPs were calculated to be in the range of 12-18 nm. From the UV-visible studies, the plasmon peak position of Ta NPs was observed in the spectral range of 206-208 nm. The XRD spectra clearly showed the crystalline structure of NPs and various peaks of Ta and Ta2O5. Moreover, the UV region in the PL spectrum included the free exciton and the bound exciton emission correlated with the defect concentration. In fact, the laser ablation in the organic and inorganic solvents is a strong technique to obtain some NPs with particular structures, which are impossible to produce by conventional methods.

Protective effect of maghemite nanoparticles on ultraviolet-induced photo-damage in human skin fibroblasts

NASA Astrophysics Data System (ADS)

Lee, Kwon-Jai; An, Jeung-Hee; Shin, Jae-Soo; Kim, Dong-Hee; Kim, Changman; Ozaki, Hajime; Koh, Jae-Gui

2007-11-01

This study examined the optical properties of an oxidized form of maghemite (γ-Fe2O3) nanoparticles and their protective effects against the photoaging of human skin fibroblasts irradiated with ultraviolet (UV) light. Nanoparticles with diameters ranging from 8.7 to 12 nm were prepared using a chemical co-precipitation method. The nanoparticles were coated with two surfactants to obtain a water-based product. The onset of the absorption of the γ-Fe2O3 nanoparticles in the UV-visible absorption spectra increased with increasing particle size. The γ-Fe2O3 nanoparticles significantly inhibited the production of matrix metalloproteinase-1 in human skin fibroblast HS 68 cells by 60% compared with the UV-irradiated control. These results suggest that γ-Fe2O3 nanoparticles have photoprotective properties, and have potential use as an agent against photoaging.

Combined In Situ Illumination-NMR-UV/Vis Spectroscopy: A New Mechanistic Tool in Photochemistry.

PubMed

Seegerer, Andreas; Nitschke, Philipp; Gschwind, Ruth M

2018-06-18

Synthetic applications in photochemistry are booming. Despite great progress in the development of new reactions, mechanistic investigations are still challenging. Therefore, we present a fully automated in situ combination of NMR spectroscopy, UV/Vis spectroscopy, and illumination to allow simultaneous and time-resolved detection of paramagnetic and diamagnetic species. This optical fiber-based setup enables the first acquisition of combined UV/Vis and NMR spectra in photocatalysis, as demonstrated on a conPET process. Furthermore, the broad applicability of combined UVNMR spectroscopy for light-induced processes is demonstrated on a structural and quantitative analysis of a photoswitch, including rate modulation and stabilization of transient species by temperature variation. Owing to the flexibility regarding the NMR hardware, temperature, and light sources, we expect wide-ranging applications of this setup in various research fields. © 2018 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Molecular basis for the Kallmann syndrome-linked fibroblast growth factor receptor mutation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thurman, Ryan D.; Kathir, Karuppanan Muthusamy; Rajalingam, Dakshinamurthy

Highlights: Black-Right-Pointing-Pointer The structural basis of the Kallmann syndrome is elucidated. Black-Right-Pointing-Pointer Kallmann syndrome mutation (A168S) induces a subtle conformational change(s). Black-Right-Pointing-Pointer Structural interactions mediated by beta-sheet G are most perturbed. Black-Right-Pointing-Pointer Ligand (FGF)-receptor interaction(s) is completely abolished by Kallmann mutation. Black-Right-Pointing-Pointer Kallmann mutation directly affects the FGF signaling process. -- Abstract: Kallmann syndrome (KS) is a developmental disease that expresses in patients as hypogonadotropic hypogonadism and anosmia. KS is commonly associated with mutations in the extracellular D2 domain of the fibroblast growth factor receptor (FGFR). In this study, for the first time, the molecular basis for the FGFR associatedmore » KS mutation (A168S) is elucidated using a variety of biophysical experiments, including multidimensional NMR spectroscopy. Secondary and tertiary structural analysis using far UV circular dichroism, fluorescence and limited trypsin digestion assays suggest that the KS mutation induces subtle tertiary structure change in the D2 domain of FGFR. Results of isothermal titration calorimetry experiments show the KS mutation causes a 10-fold decrease in heparin binding affinity and also a complete loss in ligand (FGF-1) binding. {sup 1}H-{sup 15}N chemical perturbation data suggest that complete loss in the ligand (FGF) binding affinity is triggered by a subtle conformational change that disrupts crucial structural interactions in both the heparin and the FGF binding sites in the D2 domain of FGFR. The novel findings reported in this study are expected to provide valuable clues toward a complete understanding of the other genetic diseases linked to mutations in the FGFR.« less

The Relationship between Ultraviolet Line Emission and Magnetic Field Strength in Magnetic Cataclysmic Variables

NASA Astrophysics Data System (ADS)

Howell, Steve B.; Cash, Jennifer; Mason, Keith O.; Herzog, Adrienne E.

1999-02-01

We present the first UV spectral observations of six magnetic cataclysmic variables discovered by the ROSAT Wide Field Camera (WFC). Using the^ International Ultraviolet Explorer (IUE), 1200-3400 Å spectra were obtained of the AM Herculis stars RE 0531-46, RE 1149+28, RE 1844-74, QS Tel (RE 1938-46), and HU Aqr (RE 2107-05) and the DQ Herculis star PQ Gem (RE 0751+14). The high-state UV spectra are dominated by strong emission lines. Continuum flux distributions for these stars (from 100 to 5500 Å) reveal that over this entire range, none of the spectral energy distributions can be fitted by a single-valued blackbody. Our new UV observations and additional archival IUE spectra were used to discover a correlation between the strength of the high-state UV emission lines and the strength of the white dwarf magnetic field. Model spectral results are used to confirm the production of the UV emission lines by photoionization from X-ray and EUV photons.

Application of in operando UV/Vis spectroscopy in lithium-sulfur batteries.

PubMed

Patel, Manu U M; Dominko, Robert

2014-08-01

Application of UV/Vis spectroscopy for the qualitative and quantitative determination of differences in the mechanism of lithium-sulfur battery behavior is presented. With the help of catholytes prepared from chemically synthesized stoichiometric mixtures of lithium and sulfur, calibration curves for two different types of electrolyte can be constructed. First-order derivatives of UV/Vis spectra show five typical derivative peak positions in both electrolytes. In operando measurements show a smooth change in the UV/Vis spectra in the wavelength region between λ=650 and 400 nm. Derivatives are in agreement with derivative peak positions observed with catholytes. Recalculation of normalized reflections of UV/Vis spectra obtained in operando mode enable the formation of polysulfides and their concentrations to be followed. In such a way, it is possible to distinguish differences in the mechanism of polysulfide shuttling between two electrolytes and to correlate differences in capacity fading. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermal behavior of J-aggregates in a Langmuir-Blodgett film of pure merocyanine dye investigated by UV-visible and IR absorption spectroscopy.

PubMed

Hirano, Yoshiaki; Tateno, Shinsuke; Maio, Ari; Ozaki, Yukihiro

2009-03-05

We have characterized the structure of J-aggregate in a Langmuir-Blodgett film of pure merocyanine dye (MS18) fabricated under an aqueous subphase containing a cadmium ion (Cd2+) and have investigated its thermal behavior by UV-visible and IR absorption spectroscopy in the range from 25 to 250 degrees C with a continuous scan. The results of both UV-visible and IR absorption spectra indicate that temperature-dependent changes in the MS18 aggregation state in the pure MS18 system are closely and mildly linked with the MS18 intramolecular charge transfer and the behavior of the packing, orientation, conformation, and thermal mobility of MS18 hydrocarbon chain, respectively. The J-aggregate in the pure MS18 system dissociates from 25 to 150 degrees C, and the dissociation temperature at 150 degrees C is higher by 50 degrees C than that in the previous MS18- arachidic acid (C20) binary system. The lower dissociation temperature in the binary system originates from the fact that temperature-dependent structural disorder of cadmium arachidate (CdC20), being phase-separated from MS18, has an influence on the dissociation of J-aggregate. From 160 to 180 degrees C, thermally induced blue-shifted bands, caused by the oligomeric MS18 aggregation, appear at around 520 nm in the pure MS18 system by contraries, regardless of the lack of driving force by the melting phenomenon of CdC20. The temperature at which the 520 nm bands occur is in good agreement with the melting point (160 degrees C) of hydrocarbon chain in MS18 with Cd2+, whereas its chromophore part is clearly observed to melt near 205 degrees C by UV-visible spectra. Therefore, it is suggested that the driving force that induces the 520 nm band in the pure MS18 system arises from the partial melting of hydrocarbon chain in MS18 with Cd2+.

Novel Galvanic Corrosion Inhibitors: Synthesis, Characterization, Fabrication and Testing

DTIC Science & Technology

2007-09-30

have attempted to develop methods based on chemical structural modification to prevent galvanically-induced composite corrosion. [9, 10-12] These...of the two metallopolymers 11 and 12 show characteristic MLCT (metal-to-ligand charge transfer) absorption band of tris(bipyridyl)Ru(II) unit at k...showed absorption band at 450 nm and emission band at 325 nm of tris(bipyridyl)Ru(II) units in its respective UV-vis and fluorescence spectra. Very

Structural and optical properties of CuO in zinc phosphate glasses and effects of gamma irradiation

NASA Astrophysics Data System (ADS)

Ouis, M. A.; ElBatal, H. A.; Abdelghany, A. M.; Hammad, Ahmed H.

2016-01-01

Collective optical and infrared measurements have been employed to investigate the state of increasing copper ions in host 0.5ZnO-0.5P2O5 glass composition. The same spectral measurements were repeated after gamma irradiation with a dose of 20 and 80 KGy. Optical absorption spectra reveal strong UV absorption due to trace ferric ions present as unavoidable impurities within the chemicals used in the preparation of the glasses. Copper containing glasses show an additional broad visible-near infrared band due to distorted octahedrally coordinated Cu2+ ions which at high CuO contents exhibit splitting to several component absorption peaks. Gamma irradiation causes several variations between the response of the base host zinc phosphate glass and effect of increasing CuO. These changes are correlated with both the formation of induced defects through suggested photochemical reactions in the UV region and some shielding effects with increasing CuO in the visible-near infrared spectrum. Infrared absorption spectra reveal repetitive vibrational bands due to phosphate groups mainly from metaphosphate units and the spectra show some variations with the increase of CuO content visualize by the increase of the intensity of the mid broad band extending in the range 800-1500 cm-1.

Elaboration, structural and optical investigations of ZnO/epoxy nanocomposites

NASA Astrophysics Data System (ADS)

Moussa, S.; Namouchi, F.; Guermazi, H.

2015-07-01

Hybrid nanocomposites were elaborated by incorporating ZnO nanoparticles into a transparent epoxy polymer matrix, using the direct dispersion method. The effect of the nanoparticles on the structural and optical properties of the polymer matrix was investigated using Fourier transform infrared (FTIR), Raman and UV-Visible spectroscopies. Nanocomposites FTIR spectra showed a variation of band intensities attributed to nanoparticles agglomeration within the polymer. The UV-Visible measurements showed a redshift on the band gap energy of the nanocomposites differently from neat epoxy resin, caused by interactions between ZnO NPs and polymer chains. Raman spectra confirm these interactions and the formation of hydrogen bonds in the nanocomposites. The UV-Visible transmittance spectra revealed that addition of a very low concentration (0.2wt%) of ZnO nanoparticles to a transparent epoxy matrix would maintain high visible-light transparency. The decrease of transmittance with increasing ZnO percentage is due to light scattering which originates from the agglomeration of nanoparticles in the matrix, the mismatch between the refractive index of ZnO and that of the epoxy matrix, and the increase of the surface roughness of the nanocomposite with increasing ZnO addition. Moreover, the UV-vis absorption spectra revealed that adding more than 1wt% ZnO leads to the improvement of the UV shielding properties of the nanocomposites. These results prove that the elaborated ZnO/epoxy nanocomposites can be used as UV shielding materials.

Can narrow-bandwidth light from UV-A to green alter secondary plant metabolism and increase Brassica plant defenses against aphids?

PubMed

Rechner, Ole; Neugart, Susanne; Schreiner, Monika; Wu, Sasa; Poehling, Hans-Michael

2017-01-01

Light of different wavelengths is essential for plant growth and development. Short-wavelength radiation such as UV can shift the composition of flavonoids, glucosinolates, and other plant metabolites responsible for enhanced defense against certain herbivorous insects. The intensity of light-induced, metabolite-based resistance is plant- and insect species-specific and depends on herbivore feeding guild and specialization. The increasing use of light-emitting diodes (LEDs) in horticultural plant production systems in protected environments enables the creation of tailor-made light scenarios for improved plant cultivation and induced defense against herbivorous insects. In this study, broccoli (Brassica oleracea var. italica) plants were grown in a climate chamber under broad spectra photosynthetic active radiation (PAR) and were additionally treated with the following narrow-bandwidth light generated with LEDs: UV-A (365 nm), violet (420 nm), blue (470 nm), or green (515 nm). We determined the influence of narrow-bandwidth light on broccoli plant growth, secondary plant metabolism (flavonol glycosides and glucosinolates), and plant-mediated light effects on the performance and behavior of the specialized cabbage aphid Brevicoryne brassicae. Green light increased plant height more than UV-A, violet, or blue LED treatments. Among flavonol glycosides, specific quercetin and kaempferol glycosides were increased under violet light. The concentration of 3-indolylmethyl glucosinolate in plants was increased by UV-A treatment. B. brassicae performance was not influenced by the different light qualities, but in host-choice tests, B. brassicae preferred previously blue-illuminated plants (but not UV-A-, violet-, or green-illuminated plants) over control plants.

Can narrow-bandwidth light from UV-A to green alter secondary plant metabolism and increase Brassica plant defenses against aphids?

PubMed Central

Neugart, Susanne; Schreiner, Monika; Wu, Sasa; Poehling, Hans-Michael

2017-01-01

Light of different wavelengths is essential for plant growth and development. Short-wavelength radiation such as UV can shift the composition of flavonoids, glucosinolates, and other plant metabolites responsible for enhanced defense against certain herbivorous insects. The intensity of light-induced, metabolite-based resistance is plant- and insect species-specific and depends on herbivore feeding guild and specialization. The increasing use of light-emitting diodes (LEDs) in horticultural plant production systems in protected environments enables the creation of tailor-made light scenarios for improved plant cultivation and induced defense against herbivorous insects. In this study, broccoli (Brassica oleracea var. italica) plants were grown in a climate chamber under broad spectra photosynthetic active radiation (PAR) and were additionally treated with the following narrow-bandwidth light generated with LEDs: UV-A (365 nm), violet (420 nm), blue (470 nm), or green (515 nm). We determined the influence of narrow-bandwidth light on broccoli plant growth, secondary plant metabolism (flavonol glycosides and glucosinolates), and plant-mediated light effects on the performance and behavior of the specialized cabbage aphid Brevicoryne brassicae. Green light increased plant height more than UV-A, violet, or blue LED treatments. Among flavonol glycosides, specific quercetin and kaempferol glycosides were increased under violet light. The concentration of 3-indolylmethyl glucosinolate in plants was increased by UV-A treatment. B. brassicae performance was not influenced by the different light qualities, but in host-choice tests, B. brassicae preferred previously blue-illuminated plants (but not UV-A-, violet-, or green-illuminated plants) over control plants. PMID:29190278

MUTATION SPECTRA OF SMOKY COAL COMBUSTION EMMISSIONS IN SALMONELLA REFLECTS THE TP53 AND KRAS MUTATIONS IN LUNG TUMORS FROM SMOKY COAL EXPOSED INDIVIDUALS

EPA Science Inventory

Mutation Spectra of Smoky Coal Combustion Emissions in Salmonella Reflect the TP53
and KRAS Mutations in Lung Tumors from Smoky Coal-Exposed Individuals

Abstract
Nonsmoking women in Xuan Wei County, Yunnan Province, China who use smoky coal for cooking and h...

Search for Organic Matter in Leonid Meteoroids

NASA Technical Reports Server (NTRS)

Rairden, Richard L.; Jenniskens, Peter; Laux, Christophe O.; DeVincenzi, Donald L. (Technical Monitor)

2000-01-01

Near-ultraviolet 300-410 nm spectra of Leonid meteors were obtained in an effort to measure the strong B to X emission band of the radical CN in Leonid meteor spectra at 387 nm. CN is an expected product of ablation of nitrogen containing organic carbon in the meteoroids as well as a possible product of the aerothermochemistry induced by the kinetic energy of the meteor. A slitless spectrograph with objective grating was deployed on FISTA during the 1999 Leonid Multi-Instrument Aircraft Campaign. Fifteen first-order UV spectra were captured near the 02:00 UT meteor storm peak on November 18. It is found that neutral iron lines dominate the spectrum, with no clear sign of the CN band. The meteor plasma contains less than one CN molecule per three Fe atoms at the observed altitude of about 100 km.

An atlas of ultraviolet spectra of star-forming galaxies

NASA Technical Reports Server (NTRS)

Kinney, A. L.; Bohlin, R. C.; Calzetti, D.; Panagia, N.; Wyse, Rosemary F. G.

1993-01-01

A systematic study is presented of the UV spectra of star-forming galaxies of different morphological type and activity class using a sample drawn from a uniformly reduced IUE data set. The spectra for a wide variety of galaxies, including normal spiral, LINER, starburst, blue compact, blue compact dwarf, and Seyfert 2 galaxies, are presented in the form of spectral energy distributions to demonstrate the overall characteristics according to morphology and activity class and in the form of absolute flux distributions to better show the absorption and emission features of individual objects. The data support the picture based on UV spectra of the Orbiting Astronomical Observatory and of the Astronautical Netherlands Satellite that spiral galaxies of later Hubble class have more flux at the shortest UV wavelengths than do spiral galaxies of earlier Hubble class.

A Landscape of Driver Mutations in Melanoma

PubMed Central

Hodis, Eran; Watson, Ian R.; Kryukov, Gregory V.; Arold, Stefan T.; Imielinski, Marcin; Theurillat, Jean-Philippe; Nickerson, Elizabeth; Auclair, Daniel; Li, Liren; Place, Chelsea; DiCara, Daniel; Ramos, Alex H.; Lawrence, Michael S.; Cibulskis, Kristian; Sivachenko, Andrey; Voet, Douglas; Saksena, Gordon; Stransky, Nicolas; Onofrio, Robert C.; Winckler, Wendy; Ardlie, Kristin; Wagle, Nikhil; Wargo, Jennifer; Chong, Kelly; Morton, Donald L.; Stemke-Hale, Katherine; Chen, Guo; Noble, Michael; Meyerson, Matthew; Ladbury, John E.; Davies, Michael A.; Gershenwald, Jeffrey E.; Wagner, Stephan N.; Hoon, Dave S.B.; Schadendorf, Dirk; Lander, Eric S.; Gabriel, Stacey B.; Getz, Gad; Garraway, Levi A.; Chin, Lynda

2012-01-01

SUMMARY Despite recent insights into melanoma genetics, systematic surveys for driver mutations are challenged by an abundance of passenger mutations caused by carcinogenic ultraviolet (UV) light exposure. We developed a permutation-based framework to address this challenge, employing mutation data from intronic sequences to control for passenger mutational load on a per gene basis. Analysis of large-scale melanoma exome data by this approach discovered six novel melanoma genes (PPP6C, RAC1, SNX31, TACC1, STK19 and ARID2), three of which - RAC1, PPP6C and STK19 - harbored recurrent and potentially targetable mutations. Integration with chromosomal copy number data contextualized the landscape of driver mutations, providing oncogenic insights in BRAF- and NRAS-driven melanoma as well as those without known NRAS/BRAF mutations. The landscape also clarified a mutational basis for RB and p53 pathway deregulation in this malignancy. Finally, the spectrum of driver mutations provided unequivocal genomic evidence for a direct mutagenic role of UV light in melanoma pathogenesis. PMID:22817889

Experimental and time-dependent density functional theory characterization of the UV-visible spectra of monomeric and μ-oxo dimeric ferriprotoporphyrin IX.

PubMed

Kuter, David; Venter, Gerhard A; Naidoo, Kevin J; Egan, Timothy J

2012-10-01

Speciation of ferriprotoporphyrin IX, Fe(III)PPIX, in aqueous solution is complex. Despite the use of its characteristic spectroscopic features for identification, the theoretical basis of the unique UV-visible absorbance spectrum of μ-[Fe(III)PPIX](2)O has not been explored. To investigate this and to establish a structural and spectroscopic model for Fe(III)PPIX species, density functional theory (DFT) calculations were undertaken for H(2)O-Fe(III)PPIX and μ-[Fe(III)PPIX](2)O. The models agreed with related Fe(III)porphyrin crystal structures and reproduced vibrational spectra well. The UV-visible absorbance spectra of H(2)O-Fe(III)PPIX and μ-[Fe(III)PPIX](2)O were calculated using time-dependent DFT and reproduced major features of the experimental spectra of both. Transitions contributing to calculated excitations have been identified. The features of the electronic spectrum calculated for μ-[Fe(III)PPIX](2)O were attributed to delocalization of electron density between the two porphyrin rings of the dimer, the weaker ligand field of the axial ligand, and antiferromagnetic coupling of the Fe(III) centers. Room temperature magnetic circular dichroism (MCD) spectra have been recorded and are shown to be useful in distinguishing between these two Fe(III)PPIX species. Bands underlying major spectroscopic features were identified through simultaneous deconvolution of UV-visible and MCD spectra. Computed UV-visible spectra were compared to deconvoluted spectra. Interpretation of the prominent bands of H(2)O-Fe(III)PPIX largely conforms to previous literature. Owing to the weak paramagnetism of μ-[Fe(III)PPIX](2)O at room temperature and the larger number of underlying excitations, interpretation of its experimental UV-visible spectrum was necessarily tentative. Nonetheless, comparison with the calculated spectra of antiferromagnetically coupled and paramagnetic forms of the μ-oxo dimer of Fe(III)porphine suggested that the composition of the Soret band involves a mixture of π→π* and π→d(π) charge transfer transitions. The Q-band and charge transfer bands appear to amalgamate into a mixed low energy envelope consisting of excitations with heavily admixed π→π* and charge transfer transitions.

Revived STIS. II. Properties of Stars in the Next Generation Spectral Library

NASA Technical Reports Server (NTRS)

Heap, Sara R.; Lindler, D.

2010-01-01

Spectroscopic surveys of galaxies at high redshift will bring the rest-frame ultraviolet into view of large, ground-based telescopes. The UV-blue spectral region is rich in diagnostics, but these diagnostics have not yet been calibrated in terms of the properties of the responsible stellar population(s). Such calibrations are now possible with Hubble's Next Generation Spectral Library (NGSL). The NGSL contains UV-optical spectra (0.2 - 1.0 microns) of 374 stars having a wide range in temperature, luminosity, and metallicity. We will describe our work to derive basic stellar parameters from NGSL spectra using modern model spectra and to use these stellar parameters to develop UV-blue spectral diagnostics.

Germline Mutations of BRCA1 and BRCA2 in Korean Ovarian Cancer Patients: Finding Founder Mutations.

PubMed

Choi, Min Chul; Heo, Jin-Hyung; Jang, Ja-Hyun; Jung, Sang Geun; Park, Hyun; Joo, Won Duk; Lee, Chan; Lee, Je Ho; Lee, Jun Mo; Hwang, Yoon Young; Kim, Seung Jo

2015-10-01

To investigate and analyze the BRCA mutations in Korean ovarian cancer patients with or without family history and to find founder mutations in this group. One hundred two patients who underwent a staging operation for pathologically proven epithelial cancer between January 2013 and December 2014 were enrolled. Thirty-two patients declined to analyze BRCA1/2 gene alterations after genetic counseling and pedigree analysis. Lymphocyte specimens from peripheral blood were assessed for BRCA1/2 by direct sequencing. BRCA genetic test results of 70 patients were available. Eighteen BRCA1/2 mutations and 17 unclassified variations (UVs) were found. Five of the BRCA1/2 mutations and 4 of the UVs were not reported in the Breast Cancer Information Core database. One BRCA2 UV (8665_8667delGGA) was strongly suspicious to be a deleterious mutation. BRCA1/2 mutations were identified in 11 (61.1%) of 18 patients with a family history and in 7 (13.5%) of 52 patients without a family history.Candidates for founder mutations in Korean ovarian cancer patients were assessed among 39 BRCA1/2 mutations from the present study and from literature reviews. The analysis showed that 1041_1043delAGCinsT (n = 4; 10.2%) and 3746insA (n = 4; 10.2%) were possible BRCA1 founder mutations. Only one of the BRCA2 mutations (5804_5807delTTAA) was repeated twice (n = 2; 5.1%). The prevalence of BRCA1/2 mutations in Korean ovarian cancer patients irrespective of the family history was significantly higher than previously reported. Possible founder mutations in Korean ovarian cancer patients were identified.

Application of Time-Dependent Density Functional and Natural Bond Orbital Theories to the UV-vis Absorption Spectra of Some Phenolic Compounds.

PubMed

Marković, Svetlana; Tošović, Jelena

2015-09-03

The UV-vis properties of 22 natural phenolic compounds, comprising anthraquinones, neoflavonoids, and flavonoids were systematically examined. The time-dependent density functional theory (TDDFT) approach in combination with the B3LYP, B3LYP-D2, B3P86, and M06-2X functionals was used to simulate the UV-vis spectra of the investigated compounds. It was shown that all methods exhibit very good (B3LYP slightly better) performance in reproducing the examined UV-vis spectra. However, the shapes of the Kohn-Sham molecular orbitals (MOs) involved in electronic transitions were misleading in constructing the MO correlation diagrams. To provide better understanding of redistribution of electron density upon excitation, the natural bond orbital (NBO) analysis was applied. Bearing in mind the spatial and energetic separations, as well as the character of the π bonding, lone pair, and π* antibonding natural localized molecular orbitals (NLMOs), the "NLMO clusters" were constructed. NLMO cluster should be understood as a part of a molecule characterized with distinguished electron density. It was shown that all absorption bands including all electronic transitions need to be inspected to fully understand the UV-vis spectrum of a certain compound, and, thus, to learn more about its UV-vis light absorption. Our investigation showed that the TDDFT and NBO theories are complementary, as the results from the two approaches can be combined to interpret the UV-vis spectra. Agreement between the predictions of the TDDFT approach and those based on the NLMO clusters is excellent in the case of major electronic transitions and long wavelengths. It should be emphasized that the approach for investigation of UV-vis light absorption based on the NLMO clusters is applied for the first time.

Constraining the Accretion Mode in LINER 1.9s

NASA Astrophysics Data System (ADS)

Sabra, Bassem; Der Sahaguian, Elias; Badr, Elie

2016-01-01

The accretion mode and the dominant power source in low-ionization nuclear emission-line regions (LINERs), a class of active galactic nuclei (AGN), are still elusive. We focus on a sample of 22 LINER 1.9s (Ho et al. 1997), a subclass of LINERs that show broad Halpha lines, a signature of blackhole-powered accretion, to test the hypothesis that the ionizing continuum emitted by a radiatively inefficient accretion flow (RIAF) could lead to the LINER ultraviolet (UV) emission-line ratios. Optical line-ratio diagrams are a weak diagnostic tool in distinguishing between possible power sources (Sabra et al. 2003). We search the Mikulski Archive for Space Telescopes (MAST) for UV spectra of the objects in the above sample and also perform photoionization simulations using CLOUDY (Ferland et al. 2013). Unfortunately, only one object (NGC 1052; Gabel et al. 2000) of the 22 LINER 1.9s has UV spectra that cover many emission lines; the rest of the objects either do not have any UV spectra, the spectral coverage is in-adequate, or the spectra have very low signal-to-noise ratios. Our photoionization simulations set up two identical grids of clouds with a range of densities and ionization parameters. We illuminate one grid with radiation emitted by a thin accretion disk (AD) and we illuminate the other grid with radiation from a RIAF. We overplot the UV emission-line ratio predictions for AD and RIAF illumination, together with the available line ratios for NGC 1052. Initial results show that UV lines could be used as diagnostics for the accretion mode in AGN. More UV spectral coverage of LINER 1.9s is needed in order to more fully utilize the diagnostic powers of UV emission line ratios.

H-aggregate analysis of P3HT thin films-Capability and limitation of photoluminescence and UV/Vis spectroscopy.

PubMed

Ehrenreich, Philipp; Birkhold, Susanne T; Zimmermann, Eugen; Hu, Hao; Kim, Kwang-Dae; Weickert, Jonas; Pfadler, Thomas; Schmidt-Mende, Lukas

2016-09-01

Polymer morphology and aggregation play an essential role for efficient charge carrier transport and charge separation in polymer-based electronic devices. It is a common method to apply the H-aggregate model to UV/Vis or photoluminescence spectra in order to analyze polymer aggregation. In this work we present strategies to obtain reliable and conclusive information on polymer aggregation and morphology based on the application of an H-aggregate analysis on UV/Vis and photoluminescence spectra. We demonstrate, with P3HT as model system, that thickness dependent reflection behavior can lead to misinterpretation of UV/Vis spectra within the H-aggregate model. Values for the exciton bandwidth can deviate by a factor of two for polymer thicknesses below 150 nm. In contrast, photoluminescence spectra are found to be a reliable basis for characterization of polymer aggregation due to their weaker dependence on the wavelength dependent refractive index of the polymer. We demonstrate this by studying the influence of surface characteristics on polymer aggregation for spin-coated thin-films that are commonly used in organic and hybrid solar cells.

Photodetachment and UV-Vis spectral properties of Cl2rad -·nHO clusters: Extrapolation to bulk

NASA Astrophysics Data System (ADS)

Pathak, A. K.; Mukherjee, T.; Maity, D. K.

2008-03-01

Vertical detachment energy (VDE) and UV-Vis spectra of Cl2rad -·nHO clusters ( n = 1-11) are reported based on first principle electronic structure calculations. VDE of the hydrated clusters are calculated following second order Moller-Plesset perturbation (MP2) as well as coupled cluster theory with 6-311++G(d,p) set of basis function. The excess electron in these hydrated clusters is mainly localized over the solute Cl atoms. A linear relationship is obtained for VDE vs. ( n + 2.6) -1/3 and bulk VDE of Cl2rad - aqueous solution is calculated as 10.61 eV at CCSD(T) level of theory. UV-Vis spectra of these hydrated clusters are calculated applying CI with single electron (CIS) excitation procedure. Simulated UV-Vis spectra of Cl2rad -·10HO cluster is noted to be in excellent agreement with the reported spectra of Cl2rad - (aq) system, λmax for Cl2rad -·11HO system is calculated to be red shifted though.

UV-spektra från Hubble-teleskopet avslöjar en stjärna i Vargen som lagrar tunga isotoper av mycket tunga grundämnen.

NASA Astrophysics Data System (ADS)

Johansson, S. E.; Leckrone, D. S.; Wahlgren, G. M.

1994-09-01

UV spectra from the Hubble Space Telescope reveal a star that stores heavy isotopes of very heavy elements. Atomic and plasma physics arguments for UV spectroscopy from space borne observatories are given. As an example, the authors discuss the analysis of high resolution spectra of the chemically peculiar star χ Lupi, obtained with the Hubble Space Telescope, in terms of identification of spectral lines of very heavy elements.

Spectral Measurements of Alpha-induced Radioluminescence in Various Gases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brett, Jaclyn; Koehler, Katrina Elizabeth; Bischak, Michael

Radioluminescent emission in Ar, N 2, O 2, and dry air at P=1 atm was observed induced by 5 MeV α particles. The wavelength range with a single detector spanned 250–1100 nm, extending the range well into the UV and IR bands with a single detector. Measured spectral lines for alpha-induced luminescence were corrected for detector transmission and intensities compared to previous work. The exploration of multiple gases over a wide frequency range opens the door to security and remote sensing applications, where different environments are routinely encountered. Finally, this work provides spectra that can be used in guiding futuremore » filter development focusing on remote alpha detection.« less

Spectral Measurements of Alpha-induced Radioluminescence in Various Gases

DOE PAGES

Brett, Jaclyn; Koehler, Katrina Elizabeth; Bischak, Michael; ...

2017-09-06

Radioluminescent emission in Ar, N 2, O 2, and dry air at P=1 atm was observed induced by 5 MeV α particles. The wavelength range with a single detector spanned 250–1100 nm, extending the range well into the UV and IR bands with a single detector. Measured spectral lines for alpha-induced luminescence were corrected for detector transmission and intensities compared to previous work. The exploration of multiple gases over a wide frequency range opens the door to security and remote sensing applications, where different environments are routinely encountered. Finally, this work provides spectra that can be used in guiding futuremore » filter development focusing on remote alpha detection.« less

Interactions of benzotriazole UV stabilizers with human serum albumin: Atomic insights revealed by biosensors, spectroscopies and molecular dynamics simulations.

PubMed

Zhuang, Shulin; Wang, Haifei; Ding, Keke; Wang, Jiaying; Pan, Liumeng; Lu, Yanli; Liu, Qingjun; Zhang, Chunlong

2016-02-01

Benzotriazole UV stabilizers (BZTs) belong to one prominent group of ultraviolet (UV) stabilizers and are widely used in various plastics materials. Their large production volumes, frequent detections in the environment and potential toxicities have raised increasing public concern. BZTs can be transported in vivo by transport proteins in plasma and the binding association to transport proteins may serve as a significant parameter to evaluate the bioaccumulative potential. We utilized a novel HSA biosensor, circular dichroism spectroscopy, fluorescence spectroscopy to detect the dynamic interactions of six BZTs (UV-326, UV-327, UV-328, UV-329, UV-P, and BZT) with human serum albumin (HSA), and characterized the corresponding structure-activity relationships (SAR) by molecular dynamics simulations. All test BZTs potently bind at Sudlow site I of HSA with a binding constant of 10(4) L/mol at 298 K. Minor changes in the moieties of BZTs affect their interactions with HSA and differently induce conformations of HSA. Their binding reduced electrochemical impedance spectra and α-helix content of HSA, caused slight red-shifted emission, and changed fluorescence lifetime components of HSA in a concentration-dependent mode. UV-327 and UV-329 form hydrogen bonds with HSA, while UV-329, UV-P and BZT bind HSA with more favorable electrostatic interactions. Our in vitro and in silico study offered a significant framework toward the understanding of risk assessment of BZTs and provides guide for future design of environmental benign BZTs-related materials. Copyright © 2015 Elsevier Ltd. All rights reserved.

Chemometric classification of Chinese lager beers according to manufacturer based on data fusion of fluorescence, UV and visible spectroscopies.

PubMed

Tan, Jin; Li, Rong; Jiang, Zi-Tao

2015-10-01

We report an application of data fusion for chemometric classification of 135 canned samples of Chinese lager beers by manufacturer based on the combination of fluorescence, UV and visible spectroscopies. Right-angle synchronous fluorescence spectra (SFS) at three wavelength difference Δλ=30, 60 and 80 nm and visible spectra in the range 380-700 nm of undiluted beers were recorded. UV spectra in the range 240-400 nm of diluted beers were measured. A classification model was built using principal component analysis (PCA) and linear discriminant analysis (LDA). LDA with cross-validation showed that the data fusion could achieve 78.5-86.7% correct classification (sensitivity), while those rates using individual spectroscopies ranged from 42.2% to 70.4%. The results demonstrated that the fluorescence, UV and visible spectroscopies complemented each other, yielding higher synergic effect. Copyright © 2015 Elsevier Ltd. All rights reserved.

Chromosomal mutations and chromosome loss measured in a new human-hamster hybrid cell line, ALC: studies with colcemid, ultraviolet irradiation, and 137Cs gamma-rays

NASA Technical Reports Server (NTRS)

Kraemer, S. M.; Waldren, C. A.; Chatterjee, A. (Principal Investigator)

1997-01-01

Small mutations, megabase deletions, and aneuploidy are involved in carcinogenesis and genetic defects, so it is important to be able to quantify these mutations and understand mechanisms of their creation. We have previously quantified a spectrum of mutations, including megabase deletions, in human chromosome 11, the sole human chromosome in a hamster-human hybrid cell line AL. S1- mutants have lost expression of a human cell surface antigen, S1, which is encoded by the M1C1 gene at 11p13 so that mutants can be detected via a complement-mediated cytotoxicity assay in which S1+ cells are killed and S1- cells survive. But loss of genes located on the tip of the short arm of 11 (11p15.5) is lethal to the AL hybrid, so that mutants that have lost the entire chromosome 11 die and escape detection. To circumvent this, we fused AL with Chinese hamster ovary (CHO) cells to produce a new hybrid, ALC, in which the requirement for maintaining 11p15.5 is relieved, allowing us to detect mutations events involving loss of 11p15.5. We evaluated the usefulness of this hybrid by conducting mutagenesis studies with colcemid, 137Cs gamma-radiation and UV 254 nm light. Colcemid induced 1000 more S1- mutants per unit dose in ALC than in AL; the increase for UV 254 nm light was only two-fold; and the increase for 137Cs gamma-rays was 12-fold. The increase in S1- mutant fraction in ALC cells treated with colcemid and 137Cs gamma-rays were largely due to chromosome loss and 11p deletions often containing a breakpoint within the centromeric region.

Checkpoint Defects Leading to Premature Mitosis Also Cause Endoreplication of DNA in Aspergillus nidulans

PubMed Central

De Souza, Colin P. C.; Ye, Xiang S.; Osmani, Stephen A.

1999-01-01

The G2 DNA damage and slowing of S-phase checkpoints over mitosis function through tyrosine phosphorylation of NIMXcdc2 in Aspergillus nidulans. We demonstrate that breaking these checkpoints leads to a defective premature mitosis followed by dramatic rereplication of genomic DNA. Two additional checkpoint functions, uvsB and uvsD, also cause the rereplication phenotype after their mutation allows premature mitosis in the presence of low concentrations of hydroxyurea. uvsB is shown to encode a rad3/ATR homologue, whereas uvsD displays homology to rad26, which has only previously been identified in Schizosaccharomyces pombe. uvsBrad3 and uvsDrad26 have G2 checkpoint functions over mitosis and another function essential for surviving DNA damage. The rereplication phenotype is accompanied by lack of NIMEcyclinB, but ectopic expression of active nondegradable NIMEcyclinB does not arrest DNA rereplication. DNA rereplication can also be induced in cells that enter mitosis prematurely because of lack of tyrosine phosphorylation of NIMXcdc2 and impaired anaphase-promoting complex function. The data demonstrate that lack of checkpoint control over mitosis can secondarily cause defects in the checkpoint system that prevents DNA rereplication in the absence of mitosis. This defines a new mechanism by which endoreplication of DNA can be triggered and maintained in eukaryotic cells. PMID:10564263

Benchmark studies of UV-vis spectra simulation for cinnamates with UV filter profile.

PubMed

Garcia, Ricardo D'A; Maltarollo, Vinícius G; Honório, Káthia M; Trossini, Gustavo H G

2015-06-01

Skin cancer is a serious public health problem worldwide, being incident over all five continents and affecting an increasing number of people. As sunscreens are considered an important preventive measure, studies to develop better and safer sunscreens are crucial. Cinnamates are UVB filters with good efficiency and cost-benefit, therefore, their study could lead to the development of new UV filters. A benchmark to define the most suitable density functional theory (DFT) functional to predict UV-vis spectra for ethylhexyl methoxycinnamate was performed. Time-dependent DFT (TD-DFT) calculations were then carried out [B3LYP/6-311 + G(d,p) and B3P86/6-311 + G(d,p) in methanol environment] for seven cinammete derivatives implemented in the Gaussian 03 package. All DFT/TD-DFT simulations were performed after a conformational search with the Monte-Carlo method and MMFF94 force field. B3LYP and B3P86 functionals were better at reproducing closely the experimental spectra of ethylhexyl methoxycinnamate. Calculations of seven cinnamates showed a λmax of around 310 nm, corroborating literature reports. It was observed that the energy for the main electronic transition was around 3.95 eV and could be explained by electron delocalization on the aromatic ring and ester group, which is important to UV absorption. The methodology employed proved to be suitable for determination of the UV spectra of cinnamates and could be used as a tool for the development of novel UV filters.

Two-Dimensional Electronic Spectroscopy of Benzene, Phenol, and Their Dimer: An Efficient First-Principles Simulation Protocol.

PubMed

Nenov, Artur; Mukamel, Shaul; Garavelli, Marco; Rivalta, Ivan

2015-08-11

First-principles simulations of two-dimensional electronic spectroscopy in the ultraviolet region (2DUV) require computationally demanding multiconfigurational approaches that can resolve doubly excited and charge transfer states, the spectroscopic fingerprints of coupled UV-active chromophores. Here, we propose an efficient approach to reduce the computational cost of accurate simulations of 2DUV spectra of benzene, phenol, and their dimer (i.e., the minimal models for studying electronic coupling of UV-chromophores in proteins). We first establish the multiconfigurational recipe with the highest accuracy by comparison with experimental data, providing reference gas-phase transition energies and dipole moments that can be used to construct exciton Hamiltonians involving high-lying excited states. We show that by reducing the active spaces and the number of configuration state functions within restricted active space schemes, the computational cost can be significantly decreased without loss of accuracy in predicting 2DUV spectra. The proposed recipe has been successfully tested on a realistic model proteic system in water. Accounting for line broadening due to thermal and solvent-induced fluctuations allows for direct comparison with experiments.

Alcohol-induced versus anion-induced states of alpha-chymotrypsinogen A at low pH.

PubMed

Khan, F; Khan, R H; Muzammil, S

2000-09-29

Characterization of conformational transition and folding intermediates is central to the study of protein folding. We studied the effect of various alcohols (trifluoroethanol (TFE), butanol, propanol, ethanol and methanol) and salts (K(3)FeCN(6), Na(2)SO(4), KClO(4) and KCl) on the acid-induced state of alpha-chymotrypsinogen A, a predominantly beta-sheet protein, at pH 2.0 by near-UV circular dichroism (CD), far-UV CD and 1-anilinonaphthalene-8-sulfonic acid (ANS) fluorescence measurements. Addition of alcohols led to an increase in ellipticity value at 222 nm indicating the formation of alpha-helical structure. The order of effectiveness of alcohols was shown to be TFE>butanol>propanol>ethanol>methanol. ANS fluorescence data showed a decrease in fluorescence intensity on alcohol addition, suggesting burial of hydrophobic patches. The near-UV CD spectra showed disruption of tertiary structure on alcohol addition. No change in ellipticity was observed on addition of salts at pH 2.0, whereas in the presence of 2 M urea, salts were found to induce a molten globule-like state as evident from the increases in ellipticity at 222 nm and ANS fluorescence indicating exposure of hydrophobic regions of the protein. The effectiveness in inducing the molten globule-like state, i.e. both increase in ellipticity at 222 nm and increase in ANS fluorescence, followed the order K(3)FeCN(6)>Na(2)SO(4)>KClO(4)>KCl. The loss of signal in the near-UV CD spectrum on addition of alcohols indicating disordering of tertiary structure results suggested that the decrease in ANS fluorescence intensity may be attributed to the unfolding of the ANS binding sites. The results imply that the alcohol-induced state had characteristics of an unfolded structure and lies between the molten globule and the unfolded state. Characterization of such partially folded states has important implications for protein folding.

Dynamic crystallography reveals early signalling events in ultraviolet photoreceptor UVR8

DOE PAGES

Zeng, Xiaoli; Ren, Zhong; Wu, Qi; ...

2015-01-08

Arabidopsis thaliana UVR8 (AtUVR8) is a long-sought-after photoreceptor that undergoes dimer dissociation in response to UV-B light. Crystallographic and mutational studies have identified two crucial tryptophan residues for UV-B responses in AtUVR8. However, the mechanism of UV-B perception and structural events leading up to dimer dissociation remain elusive at the molecular level. We applied dynamic crystallography to capture light-induced structural events in photoactive AtUVR8 crystals. Here we report two intermediate structures at 1.67Å resolution. At the epicenter of UV-B signaling, concerted motions associated with Trp285/Trp233 lead to ejection of a water molecule, which weakens an intricate network of hydrogen bondsmore » and salt bridges at the dimer interface. Partial opening of the β-propeller structure due to thermal relaxation of conformational strains originating in the epicenter further disrupts the dimer interface and leads to dimer dissociation. Ultimately, these dynamic crystallographic observations provide structural insights into the photo-perception and signaling mechanism of UVR8.« less

Inducible error-prone repair in B. subtilis. Progress report, September 1, 1978-August 31, 1979. [Role in mutagenesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yasbin, R E

1979-01-01

The mechanism of activation and the mode of action of the SOS system in the bacterium Bacillus subtilis is under study. Interesting aspects of the SOS system in B. subtilis are: (1) the differences between SOS functions in this bacterium and in the enteric bacteria; (2) the spontaneous activation of SOS functions in component cells; and (3) the difficulty in obtaining consistent results for mutation studies in this bacterium. In order to characterize the SOS system of B. subtilis, it was proposed to: (1) isolate bacteria mutated in genes controlling various repair function; (2) investigate inducible repair; (3) determine themore » role of endogeneous Bacillus prophages in SOS functions; and (4) develop a tester system for potential carcinogens from competent Bacillus subtilis cells. Research has been able to: (1) isolate strains of B. subtilis in which the endogeneous prophages have been removed or neutralized; (2) demonstrate the association of one SOS function with prophage SPB; (3) demonstrate that the survival of uv-irradiated B. subtilis is not significantly altered by the removal and neutralization of the endogeneous prophages; (4) develop competant B. subtilis into a tester system; and (5) show that DNA polymerase III is absolutely necessary for W reactivation. In addition, uv and mitomycin C resistant mutants have been isolated and inducible postreplication repair in excision-repair deficient mutants of B. subtilis has been studied. The last two results are somewaht confusing but highly exciting in regards to DNA repair mechanisms in B. subtilis.« less

Conformationally resolved spectroscopy of jet-cooled methacetin

NASA Astrophysics Data System (ADS)

Moon, Cheol Joo; Ahn, Ahreum; Min, Ahreum; Seong, Yeon Guk; Kim, Ju Hyun; Choi, Myong Yong

2017-11-01

The excitation spectra of jet-cooled methacetin (MA) have been measured using a combination of mass-selected resonant two-photon ionization and ultraviolet-ultraviolet hole-burning (UV-UV HB) spectroscopy in the gas phase. Four different UV-UV HB spectra originating from two conformers of MA (syn- and anti-MA) with their fundamental and hot transitions have been obtained. IR-dip spectroscopy has conclusively confirmed the coexistence of the two conformers with the aid of theoretical calculations. Vibronic band assignments in the low frequency region caused by internal methyl group rotation in the methyl-capped peptide group, which originate from the 1e rotational level, are presented.

A UV resonance Raman (UVRR) spectroscopic study on the extractable compounds of Scots pine ( Pinus sylvestris) wood . Part I: Lipophilic compounds

NASA Astrophysics Data System (ADS)

Nuopponen, M.; Willför, S.; Jääskeläinen, A.-S.; Sundberg, A.; Vuorinen, T.

2004-11-01

The wood resin in Scots pine ( Pinus sylvestris) stemwood and branch wood were studied using UV resonance Raman (UVRR) spectroscopy. UVRR spectra of the sapwood and heartwood hexane extracts, solid wood samples and model compounds (six resin acids, three fatty acids, a fatty acid ester, sitosterol and sitosterol acetate) were collected using excitation wavelengths of 229, 244 and 257 nm. In addition, visible Raman spectra of the fatty and resin acids were recorded. Resin compositions of heartwood and sapwood hexane extracts were determined using gas chromatography. Raman signals of both conjugated and isolated double bonds of all the model compounds were resonance enhanced by UV excitation. The oleophilic structures showed strong bands in the region of 1660-1630 cm -1. Distinct structures were enhanced depending on the excitation wavelength. The UVRR spectra of the hexane extracts showed characteristic bands for resin and fatty acids. It was possible to identify certain resin acids from the spectra. UV Raman spectra collected from the solid wood samples containing wood resin showed a band at ˜1650 cm -1 due to unsaturated resin components. The Raman signals from extractives in the resin rich branch wood sample gave even more strongly enhanced signals than the aromatic lignin.

A UV resonance Raman (UVRR) spectroscopic study on the extractable compounds of Scots pine (Pinus sylvestris) wood. Part I: lipophilic compounds.

PubMed

Nuopponen, M; Willför, S; Jääskeläinen, A-S; Sundberg, A; Vuorinen, T

2004-11-01

The wood resin in Scots pine (Pinus sylvestris) stemwood and branch wood were studied using UV resonance Raman (UVRR) spectroscopy. UVRR spectra of the sapwood and heartwood hexane extracts, solid wood samples and model compounds (six resin acids, three fatty acids, a fatty acid ester, sitosterol and sitosterol acetate) were collected using excitation wavelengths of 229, 244 and 257 nm. In addition, visible Raman spectra of the fatty and resin acids were recorded. Resin compositions of heartwood and sapwood hexane extracts were determined using gas chromatography. Raman signals of both conjugated and isolated double bonds of all the model compounds were resonance enhanced by UV excitation. The oleophilic structures showed strong bands in the region of 1660-1630 cm(-1). Distinct structures were enhanced depending on the excitation wavelength. The UVRR spectra of the hexane extracts showed characteristic bands for resin and fatty acids. It was possible to identify certain resin acids from the spectra. UV Raman spectra collected from the solid wood samples containing wood resin showed a band at approximately 1650 cm(-1) due to unsaturated resin components. The Raman signals from extractives in the resin rich branch wood sample gave even more strongly enhanced signals than the aromatic lignin.

Laboratory spectroscopy of meteorite samples at UV-vis-NIR wavelengths: Analysis and discrimination by principal components analysis

NASA Astrophysics Data System (ADS)

Penttilä, Antti; Martikainen, Julia; Gritsevich, Maria; Muinonen, Karri

2018-02-01

Meteorite samples are measured with the University of Helsinki integrating-sphere UV-vis-NIR spectrometer. The resulting spectra of 30 meteorites are compared with selected spectra from the NASA Planetary Data System meteorite spectra database. The spectral measurements are transformed with the principal component analysis, and it is shown that different meteorite types can be distinguished from the transformed data. The motivation is to improve the link between asteroid spectral observations and meteorite spectral measurements.

Pro-Apoptotic Role of the Human YPEL5 Gene Identified by Functional Complementation of a Yeast moh1Δ Mutation.

PubMed

Lee, Ji Young; Jun, Do Youn; Park, Ju Eun; Kwon, Gi Hyun; Kim, Jong-Sik; Kim, Young Ho

2017-03-28

To examine the pro-apoptotic role of the human ortholog (YPEL5) of the Drosophila Yippee protein, the cell viability of Saccharomyces cerevisiae mutant strain with deleted MOH1 , the yeast ortholog, was compared with that of the wild-type (WT)- MOH1 strain after exposure to different apoptogenic stimulants, including UV irradiation, methyl methanesulfonate (MMS), camptothecin (CPT), heat shock, and hyperosmotic shock. The moh1 Δ mutant exhibited enhanced cell viability compared with the WT- MOH1 strain when treated with lethal UV irradiation, 1.8 mM MMS, 100 µ CPT, heat shock at 50°C, or 1.2 M KCl. At the same time, the level of Moh1 protein was commonly up-regulated in the WT- MOH1 strain as was that of Ynk1 protein, which is known as a marker for DNA damage. Although the enhanced UV resistance of the moh1 Δ mutant largely disappeared following transformation with the yeast MOH1 gene or one of the human YPEL1-YPEL5 genes, the transformant bearing pYES2- YPEL5 was more sensitive to lethal UV irradiation and its UV sensitivity was similar to that of the WT- MOH1 strain. Under these conditions, the UV irradiation-induced apoptotic events, such as FITC-Annexin V stainability, mitochondrial membrane potential (ΔΨm) loss, and metacaspase activation, occurred to a much lesser extent in the moh1 Δ mutant compared with the WT- MOH1 strain and the mutant strain bearing pYES2- MOH1 or pYES2- YPEL5 . These results demonstrate the functional conservation between yeast Moh1 and human YPEL5, and their involvement in mitochondria-dependent apoptosis induced by DNA damage.

Bond Length Dependence on Quantum States as Shown by Spectroscopy

ERIC Educational Resources Information Center

Lim, Kieran F.

2005-01-01

A discussion on how a spreadsheet simulation of linear-molecular spectra could be used to explore the dependence of rotational band spacing and contours on average bond lengths in the initial and final quantum states is presented. The simulation of hydrogen chloride IR, iodine UV-vis, and nitrogen UV-vis spectra clearly show whether the average…

Airborne observations of astronomical objects

NASA Technical Reports Server (NTRS)

Sivjee, G. G.

1976-01-01

The UV spectra of the sun, as well as the differences and ratios of planetary and solar spectra, are presented. The results indicate that SO, SO2 and ClO2 may be present in Venus' atmosphere, and Formaldehyde CH2O and ClO2 on Jupiter. The solar UV measurements were analyzed to deduce ozone concentration in the earth's atmosphere.

Astrophysics Meets Atomic Physics: Fe I Line Identifications and Templates for Old Stellar Populations from Warm and Hot Stellar UV Spectra

NASA Astrophysics Data System (ADS)

Peterson, Ruth

2017-08-01

Imaging surveys from the ultraviolet to the infrared are recording ever more distant astronomical sources. Needed to interpret them are high-resolution ultraviolet spectral templates at all metallicities for both old and intermediate-age stars, and the atomic physics data essential to model their spectra. To this end we are proposing new UV spectra of four warm and hot stars spanning a wide range of metallicity. These will provide observational templates of old and young metal-poor turnoff stars, and the laboratory source for the identification of thousands of lines of neutral iron that appear in stellar spectra but are not identified in laboratory spectra. By matching existing and new stellar spectra to calculations of energy levels, line wavelengths, and gf-values, Peterson & Kurucz (2015) and Peterson, Kurucz, & Ayres (2017) identified 124 Fe I levels with energies up to 8.4eV. These provided 3000 detectable Fe I lines from 1600A to 5.4mu, and yielded empirical gf-values for 640 of these. Here we propose high-resolution UV spectra reaching 1780A for the first time at the turnoff, to detect and identify the strongest Fe I lines at 1800 - 1850A. This should add 250 new Fe I levels. These spectra, plus one at lower resolution reaching 1620A, will also provide empirical UV templates for turnoff stars at high redshifts as well as low. This is essential to deriving age and metallicity independently for globular clusters and old galaxies out to z 3. It will also improve abundances of trace elements in metal-poor stars, constraining nucleosynthesis at early epochs and aiding the reconstruction of the populations of the Milky Way halo and of nearby globular clusters.

Combining UV photodissociation action spectroscopy with electron transfer dissociation for structure analysis of gas-phase peptide cation-radicals.

PubMed

Shaffer, Christopher J; Pepin, Robert; Tureček, František

2015-12-01

We report the first example of using ultraviolet (UV) photodissociation action spectroscopy for the investigation of gas-phase peptide cation-radicals produced by electron transfer dissociation. z-Type fragment ions (●) Gly-Gly-Lys(+), coordinated to 18-crown-6-ether (CE), are generated, selected by mass and photodissociated in the 200-400 nm region. The UVPD action spectra indicate the presence of valence-bond isomers differing in the position of the Cα radical defect, (α-Gly)-Gly-Lys(+) (CE), Gly-(α-Gly)-Lys(+) (CE) and Gly-Gly-(α-Lys(+))(CE). The isomers are readily distinguishable by UV absorption spectra obtained by time-dependent density functional theory (TD-DFT) calculations. In contrast, conformational isomers of these radical types are calculated to have similar UV spectra. UV photodissociation action spectroscopy represents a new tool for the investigation of transient intermediates of ion-electron reactions. Specifically, z-type cation radicals are shown to undergo spontaneous hydrogen atom migrations upon electron transfer dissociation. Copyright © 2015 John Wiley & Sons, Ltd.

Improved discrimination between monocotyledonous and dicotyledonous plants for weed control based on the blue-green region of ultraviolet-induced fluorescence spectra.

PubMed

Panneton, Bernard; Guillaume, Serge; Roger, Jean-Michel; Samson, Guy

2010-01-01

Precision weeding by spot spraying in real time requires sensors to discriminate between weeds and crop without contact. Among the optical based solutions, the ultraviolet (UV) induced fluorescence of the plants appears as a promising alternative. In a first paper, the feasibility of discriminating between corn hybrids, monocotyledonous, and dicotyledonous weeds was demonstrated on the basis of the complete spectra. Some considerations about the different sources of fluorescence oriented the focus to the blue-green fluorescence (BGF) part, ignoring the chlorophyll fluorescence that is inherently more variable in time. This paper investigates the potential of performing weed/crop discrimination on the basis of several large spectral bands in the BGF area. A partial least squares discriminant analysis (PLS-DA) was performed on a set of 1908 spectra of corn and weed plants over 3 years and various growing conditions. The discrimination between monocotyledonous and dicotyledonous plants based on the blue-green fluorescence yielded robust models (classification error between 1.3 and 4.6% for between-year validation). On the basis of the analysis of the PLS-DA model, two large bands were chosen in the blue-green fluorescence zone (400-425 nm and 425-490 nm). A linear discriminant analysis based on the signal from these two bands also provided very robust inter-year results (classification error from 1.5% to 5.2%). The same selection process was applied to discriminate between monocotyledonous weeds and maize but yielded no robust models (up to 50% inter-year error). Further work will be required to solve this problem and provide a complete UV fluorescence based sensor for weed-maize discrimination.

Loss of second and sixth conserved cysteine residues from trypsin inhibitor-like cysteine-rich domain-type protease inhibitors in Bombyx mori may induce activity against microbial proteases.

PubMed

Li, Youshan; Liu, Huawei; Zhu, Rui; Xia, Qingyou; Zhao, Ping

2016-12-01

Previous studies have indicated that most trypsin inhibitor-like cysteine-rich domain (TIL)-type protease inhibitors, which contain a single TIL domain with ten conserved cysteines, inhibit cathepsin, trypsin, chymotrypsin, or elastase. Our recent findings suggest that Cys 2nd and Cys 6th were lost from the TIL domain of the fungal-resistance factors in Bombyx mori, BmSPI38 and BmSPI39, which inhibit microbial proteases and the germination of Beauveria bassiana conidia. To reveal the significance of these two missing cysteines in relation to the structure and function of TIL-type protease inhibitors in B. mori, cysteines were introduced at these two positions (D36 and L56 in BmSPI38, D38 and L58 in BmSPI39) by site-directed mutagenesis. The homology structure model of TIL domain of the wild-type and mutated form of BmSPI39 showed that two cysteine mutations may cause incorrect disulfide bond formation of B. mori TIL-type protease inhibitors. The results of Far-UV circular dichroism (CD) spectra indicated that both the wild-type and mutated form of BmSPI39 harbored predominantly random coil structures, and had slightly different secondary structure compositions. SDS-PAGE and Western blotting analysis showed that cysteine mutations affected the multimerization states and electrophoretic mobility of BmSPI38 and BmSPI39. Activity staining and protease inhibition assays showed that the introduction of cysteine mutations dramaticly reduced the activity of inhibitors against microbial proteases, such as subtilisin A from Bacillus licheniformis, protease K from Engyodontium album, protease from Aspergillus melleus. We also systematically analyzed the key residue sites, which may greatly influence the specificity and potency of TIL-type protease inhibitors. We found that the two missing cysteines in B. mori TIL-type protease inhibitors might be crucial for their inhibitory activities against microbial proteases. The genetic engineering of TIL-type protease inhibitors may be applied in both health care and agricultural industries, and could lead to new methods for breeding fungus-resistant transgenic crops and antifungal transgenic silkworm strains. Copyright © 2016 Elsevier Inc. All rights reserved.

Curcumin-Zn(II) complex for enhanced solubility and stability: an approach for improved delivery and pharmacodynamic effects.

PubMed

Sareen, Rashmi; Jain, Nitin; Dhar, K L

2016-08-01

The aim of present investigation was to prepare Curcumin-Zn(II) complex in a view to enhance solubility, stability and pharmacodynamic effect in experimentally induced ulcerative colitis. Curcumin-Zn(II) complex was prepared by stirring curcumin with anhydrous zinc chloride at a molar ratio of 1:1. The prepared curcumin metallocomplex was characterized by TLC, FTIR, UV spectroscopy and (1)H NMR. In vitro kinetic degradation and solubility of Curcumin and Curcumin-Zn(II) complex was analyzed spectrophotometrically. Pharmacodynamic evaluation of curcumin and its metal complex was assessed in ulcerative colitis in mice. Curcumin showed chelation with zinc ion as confirmed by the TLC, FTIR, UV spectroscopy and (1)H NMR. The results of TLC [Rf value], IR Spectroscopy [shifting of stretching vibrations of υ(C=C) and υ(C=O)], UV spectra [deconvoluted with absorption band at 432-466.4 nm] of Curcumin-Zn(II) complex compared to curcumin confirmed the formation of metallocomplex. (1)HNMR spectra of Curcumin-Zn(II) showed the upfield shift of Ha and Hb. Kinetic stability studies showed metallocomplex with zinc exhibited good stability. In vivo study revealed significant reduction in severity and extent of colonic damage with Curcumin-Zn(II) which were further confirmed by histopathological study. This study recognizes higher solubility and stability of Curcumin-Zn(II) complex and suggested better pharmacodynamic effects.

Effect of 3d-transition metal doping on the shielding behavior of barium borate glasses: a spectroscopic study.

PubMed

ElBatal, H A; Abdelghany, A M; Ghoneim, N A; ElBatal, F H

2014-12-10

UV-visible and FT infrared spectra were measured for prepared samples before and after gamma irradiation. Base undoped barium borate glass of the basic composition (BaO 40%-B2O3 60mol.%) reveals strong charge transfer UV absorption bands which are related to unavoidable trace iron impurities (Fe(3+)) within the chemical raw materials. 3d transition metal (TM)-doped glasses exhibit extra characteristic absorption bands due to each TM in its specific valence or coordinate state. The optical spectra show that TM ions favor generally the presence in the high valence or tetrahedral coordination state in barium borate host glass. Infrared absorption bands of all prepared glasses reveal the appearance of both triangular BO3 units and tetrahedral BO4 units within their characteristic vibrational modes and the TM-ions cause minor effects because of the low doping level introduced (0.2%). Gamma irradiation of the undoped barium borate glass increases the intensity of the UV absorption together with the generation of an induced broad visible band at about 580nm. These changes are correlated with suggested photochemical reactions of trace iron impurities together with the generation of positive hole center (BHC or OHC) within the visible region through generated electrons and positive holes during the irradiation process. Copyright © 2014 Elsevier B.V. All rights reserved.

Elucidating the interaction of clofazimine with bovine liver catalase; a comprehensive spectroscopic and molecular docking approach.

PubMed

Zaman, Masihuz; Nusrat, Saima; Zakariya, Syed Mohammad; Khan, Mohsin Vahid; Ajmal, Mohammad Rehan; Khan, Rizwan Hasan

2017-08-01

Nowadays, understanding of interface between protein and drugs has become an active research area of interest. These types of interactions provide structural guidelines in drug design with greater clinical efficacy. Thus, structural changes in catalase induced by clofazimine were monitored by various biophysical techniques including UV-visible spectrometer, fluorescence spectroscopy, circular dichroism, and dynamic light scattering techniques. Increase in absorption spectra (UV-visible spectrum) confers the complex formation between drug and protein. Fluorescence quenching with a binding constants of 2.47 × 10 4  M -1 revealed that clofazimine binds with protein. Using fluorescence resonance energy transfer, the distance (r) between the protein (donor) and drug (acceptor) was found to be 2.89 nm. Negative Gibbs free energy change (ΔG°) revealed that binding process is spontaneous. In addition, an increase in α-helicity was observed by far-UV circular dichroism spectra by adding clofazimine to protein. Dynamic light scattering results indicate that topology of bovine liver catalase was slightly altered in the presence of clofazimine. Hydrophobic interactions are the main forces between clofazimine and catalase interaction as depicted by molecular docking studies. Apart from hydrophobic interactions, some hydrogen bonding was also observed during docking method. The results obtained from the present study may establish abundant in optimizing the properties of ligand-protein mixtures relevant for numerous formulations. Copyright © 2017 John Wiley & Sons, Ltd.

UV and fluorescence spectral changes induced by neodymium binding of N,N'-ethylenebis[2-(o-hydroxyphenolic)glycine] and N,N'-di(2-hydroxybenzyl)ethylenediamine-N,N' diacetic acid.

PubMed

Wang, Zhijun; Yang, Binsheng

2006-11-01

In 0.01 M 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (Hepes), pH 7.4 and room temperature, the binding of neodymium to N,N'-ethylenebis[2-(o-hydroxyphenolic)glycine] (EHPG), or N,N'-di(2-hydroxybenzyl)ethylenediamine-N,N' diacetic acid (HBED) had been studied from 210 to 330 nm by means of difference UV spectra. Two peaks at 240 and 292 nm appear in difference UV spectra after neodymium binding to EHPG or HBED. The 1:1 stable complex can be confirmed from spectral titration curves. The molar extinction coefficient of Nd-EHPG and Nd-HBED complexes are Deltaepsilon(Nd-EHPG)=(12.93+/-0.21) x 10(3)cm(-1)M(-1), Deltaepsilon(Nd-HBED)=(14.45+/-0.51) x 10(5)cm(-1)M(-1) at 240 nm, respectively. Using EDTA as a competitor, the conditional equilibrium constants of the complexes are logK(Nd-EHPG)=11.89+/-0.09 and logK(Nd-HBED)=12.19+/-0.15, respectively. At the same conditions, fluorescence measurements show that neodymium binding to EHPG leads to a quenching of the fluorescence of EHPG at near 310 nm. However, there is no obvious fluorescence change of HBED at 318 nm with the binding of neodymium to HBED.

On induced-modifications in optical properties of Makrofol® DE 1-1 SSNTD by UVB and UVA

NASA Astrophysics Data System (ADS)

Al-Amri, A.; El Ghazaly, M.; Abdel-Aal, M. S.

The induced modifications in the optical properties of Makrofol® DE 1-1 solid state nuclear track detectors upon irradiation by UVB (302 nm) and UVA (365 nm) were characterized and compared. Makrofol® DE 1-1 detectors were irradiated separately for different durations with UVB (302 nm) and UVA (365 nm). The measurements revealed insignificant changes were observed at all in UVA (365 nm)-irradiated Makrofol® DE 1-1, irrespective the irradiation time (dose). All UVB (302 nm)-irradiated Makrofol® DE 1-1 detectors show a substantial red shift in UV-Vis spectra and a continuous increase in absorbance as the exposure time (Dose) to UVB increases. UVC-irradiated Makrofol® DE 1-1 exhibits absorption bands at 315 ± 5 nm in UV-visible spectra. The absorption increases exponential with the increasing the UVB irradiation time gets saturated started from 75 h to 400 h. In the visible light range no significant changes were observed in Makrofol® DE 1-1 detector irrespective the exposure time to UVB of 302 nm. It is found that the direct band gap is higher than indirect band gap and both decrease with the increase in the irradiation time of UVB of 302 nm. The obtained results of the Urbach energy and carbon atoms per cluster indicate that both increase with the increase in the irradiation time to UVB (302 nm). The induced modification in the optical properties of Makrofol® DE 1-1 can be used in UVB dosimetry, meanwhile it is not applicable for UVA of 365 nm.

Xeroderma pigmentosum complementation group E and UV-damaged DNA-binding protein

PubMed Central

Tang, Jean; Chu, Gilbert

2010-01-01

UV-damaged DNA-binding protein (UV-DDB) is composed of two subunits, DDB1 (p127) and DDB2 (p48). Mutations in the DDB2 gene inactivate UV-DDB in individuals from complementation group E of xeroderma pigmentosum (XP-E), an autosomal recessive disease characterized by sun sensitivity, severe risk for skin cancer and defective nucleotide excision repair. UV-DDB is also deficient in many rodent tissues, exposing a shortcoming in rodent models for cancer. In vitro, UV-DDB binds to cyclobutane pyrimidine dimers (CPDs), 6–4 photoproducts and other DNA lesions, stimulating the excision of CPDs, and to a lesser extent, of 6–4 photoproducts. In vivo, UV-DDB plays an important role in the p53-dependent response of mammalian cells to DNA damage. When cells are exposed to UV, the resulting accumulation of p53 activates DDB2 transcription, which leads to increased levels of UV-DDB. Binding of UV-DDB to CPDs targets these lesions for global genomic repair, suppressing mutations without affecting UV survival. Apparently, cells are able to survive with unrepaired CPDs because of the activity of bypass DNA polymerases. Finally, there is evidence that UV-DDB may have roles in the cell that are distinct from DNA repair. PMID:12509284

Role of damage-specific DNA polymerases in M13 phage mutagenesis induced by a major lipid peroxidation product trans-4-hydroxy-2-nonenal.

PubMed

Janowska, Beata; Kurpios-Piec, Dagmara; Prorok, Paulina; Szparecki, Grzegorz; Komisarski, Marek; Kowalczyk, Paweł; Janion, Celina; Tudek, Barbara

2012-01-03

One of the major lipid peroxidation products trans-4-hydroxy-2-nonenal (HNE), forms cyclic propano- or ethenoadducts bearing six- or seven-carbon atom side chains to G>C≫A>T. To specify the role of SOS DNA polymerases in HNE-induced mutations, we tested survival and mutation spectra in the lacZα gene of M13mp18 phage, whose DNA was treated in vitro with HNE, and which was grown in uvrA(-)Escherichia coli strains, carrying one, two or all three SOS DNA polymerases. When Pol IV was the only DNA SOS polymerase in the bacterial host, survival of HNE-treated M13 DNA was similar to, but mutation frequency was lower than in the strain containing all SOS DNA polymerases. When only Pol II or Pol V were present in host bacteria, phage survival decreased dramatically. Simultaneously, mutation frequency was substantially increased, but exclusively in the strain carrying only Pol V, suggesting that induction of mutations by HNE is mainly dependent on Pol V. To determine the role of Pol II and Pol IV in HNE induced mutagenesis, Pol II or Pol IV were expressed together with Pol V. This resulted in decrease of mutation frequency, suggesting that both enzymes can compete with Pol V, and bypass HNE-DNA adducts in an error-free manner. However, HNE-DNA adducts were easily bypassed by Pol IV and only infrequently by Pol II. Mutation spectrum established for strains expressing only Pol V, showed that in uvrA(-) bacteria the frequency of base substitutions and recombination increased in relation to NER proficient strains, particularly mutations at adenine sites. Among base substitutions A:T→C:G, A:T→G:C, G:C→A:T and G:C→T:A prevailed. The results suggest that Pol V can infrequently bypass HNE-DNA adducts inducing mutations at G, C and A sites, while bypass by Pol IV and Pol II is error-free, but for Pol II infrequent. Copyright © 2011 Elsevier B.V. All rights reserved.

Structural properties and UV to NIR absorption spectra of metal-free phthalocyanine (H2Pc) thin films P. B. Thakor, P. N. Gajjar and A. R. Jani: Different reference systems in the study of structural properties of some simple liquid metals Shazia Bashir, M. S. Rafique, M. Khaleeq-ur-Rahman, Faizan-ul-Haq and B. R. Alvina: CO2 and Nd:YAG laser radiation induced damage in aluminium Smail Bougouffa: The study of atomic transitions by use of Numerov technique in schematic model

NASA Astrophysics Data System (ADS)

El-Nahass, M. M.; Farid, A. M.; Attia, A. A.; Ali, H. A. M.

The structural properties and absorption spectra of H2Pc thin films have been studied. The films used in these studies were thermally evaporated on glass/quartz substrates with thickness ranging from 60 to 460 nm. The XRD studies of H2Pc thin films showed that the as-deposited films have a-form with monoclinic system. The mean crystallite size (L), the dislocation density (d) and the strain (x) were evaluated. The molecular structure of H2Pc thin films is confirmed by analysis of (FTIR) spectra. The surface morphology of H2Pc thin films was examined by scanning electron microscope. The absorption spectra of H2Pc recorded in the UV - VIS - IR region for the as-deposited and the annealed thin films of different thickness have been analyzed. The spectra showed two absorption bands namely the Q-band and the Soret (B)-band. The Q-band shows its characteristic splitting (Davydove splitting) with DQ = 0.21 eV. Values of some important optical parameters, namely optical absorption coefficient (a¢), molar extinction coefficient (emolar), half-band-width (Dl), electronic dipole strength (q2) and oscillator strength (f) were calculated. The fundamental and the onset of the indirect energy gaps were also determined as 2.47 and 1.4 eV, respectively.

Ultraviolet reflectance properties of asteroids

NASA Astrophysics Data System (ADS)

Butterworth, P. S.; Meadows, A. J.

1985-05-01

An analysis of the UV spectra of 28 asteroids obtained with the Internal Ultraviolet Explorer (IUE) satellite is presented. The spectra lie within the range 2100-3200 A. The results are examined in terms of both asteroid classification and of current ideas concerning the surface mineralogy of asteroids. For all the asteroids examined, UV reflectivity declines approximately linearly toward shorter wavelengths. In general, the same taxonomic groups are seen in the UV as in the visible and IR, although there is some evidence for asteroids with anomalous UV properties and for UV subclasses within the S class. No mineral absorption features are reported of strength similar to the strongest features in the visible and IR regions, but a number of shallow absorptions do occur and may provide valuable information on the surface composition of many asteroids.

Aromatic Cluster Sensor of Protein Folding: Near-UV Electronic Circular Dichroism Bands Assigned to Fold Compactness.

PubMed

Farkas, Viktor; Jákli, Imre; Tóth, Gábor K; Perczel, András

2016-09-19

Both far- and near-UV electronic circular dichroism (ECD) spectra have bands sensitive to thermal unfolding of Trp and Tyr residues containing proteins. Beside spectral changes at 222 nm reporting secondary structural variations (far-UV range), L b bands (near-UV range) are applicable as 3D-fold sensors of protein's core structure. In this study we show that both L b (Tyr) and L b (Trp) ECD bands could be used as sensors of fold compactness. ECD is a relative method and thus requires NMR referencing and cross-validation, also provided here. The ensemble of 204 ECD spectra of Trp-cage miniproteins is analysed as a training set for "calibrating" Trp↔Tyr folded systems of known NMR structure. While in the far-UV ECD spectra changes are linear as a function of the temperature, near-UV ECD data indicate a non-linear and thus, cooperative unfolding mechanism of these proteins. Ensemble of ECD spectra deconvoluted gives both conformational weights and insight to a protein folding↔unfolding mechanism. We found that the L b 293 band is reporting on the 3D-structure compactness. In addition, the pure near-UV ECD spectrum of the unfolded state is described here for the first time. Thus, ECD folding information now validated can be applied with confidence in a large thermal window (5≤T≤85 °C) compared to NMR for studying the unfolding of Trp↔Tyr residue pairs. In conclusion, folding propensities of important proteins (RNA polymerase II, ubiquitin protein ligase, tryptase-inhibitor etc.) can now be analysed with higher confidence. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

UV-induced association of the CSB remodeling protein with chromatin requires ATP-dependent relief of N-terminal autorepression

PubMed Central

Lake, Robert J.; Geyko, Anastasia; Hemashettar, Girish; Zhao, Yu; Fan, Hua-Ying

2009-01-01

Summary The ATP-dependent chromatin remodeler CSB is essential for transcription-coupled DNA repair, and mutations in CSB lead to Cockayne syndrome. Here we examined the recruitment of CSB to chromatin after UV irradiation and uncovered a regulatory mechanism that ensures the specific association of this remodeler with chromatin. We demonstrate that ATP hydrolysis by CSB is essential for stable CSB-chromatin association after UV irradiation, and that defects in this association underlie some forms of Cockayne syndrome. We also show that the N-terminal region of CSB negatively regulates chromatin association during normal cell growth. Interestingly, in the absence of the negative-regulatory region, ATP hydrolysis becomes dispensable for chromatin association, indicating that CSB uses energy from ATP hydrolysis to overcome the inhibitory effect imposed by its N-terminal region. Together, our results suggest that the recruitment of CSB to lesion-stalled transcription is an ATP-dependent process and involves a gross conformational change of CSB. PMID:20122405

Molten Globule-Like Partially Folded State of Bacillus licheniformis α-Amylase at Low pH Induced by 1,1,1,3,3,3-Hexafluoroisopropanol

PubMed Central

Abd Halim, Adyani Azizah; Zaroog, Mohammed Suleiman; Abdul Kadir, Habsah; Tayyab, Saad

2014-01-01

Effect of 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) on acid-denatured Bacillus licheniformis α-amylase (BLA) at pH 2.0 was investigated by far-UV CD, intrinsic fluorescence, and ANS fluorescence measurements. Addition of increasing HFIP concentrations led to an increase in the mean residue ellipticity at 222 nm (MRE222 nm) up to 1.5 M HFIP concentration beyond which it sloped off. A small increase in the intrinsic fluorescence and a marked increase in the ANS fluorescence were also observed up to 0.4 M HFIP concentration, both of which decreased thereafter. Far- and near-UV CD spectra of the HFIP-induced state observed at 0.4 M HFIP showed significant retention of the secondary structures closer to native BLA but a disordered tertiary structure. Increase in the ANS fluorescence intensity was also observed with the HFIP-induced state, suggesting exposure of the hydrophobic clusters to the solvent. Furthermore, thermal denaturation of HFIP-induced state showed a non-cooperative transition. Taken together, all these results suggested that HFIP-induced state of BLA represented a molten globule-like state at pH 2.0. PMID:24977228

UV-POSIT: Web-Based Tools for Rapid and Facile Structural Interpretation of Ultraviolet Photodissociation (UVPD) Mass Spectra

NASA Astrophysics Data System (ADS)

Rosenberg, Jake; Parker, W. Ryan; Cammarata, Michael B.; Brodbelt, Jennifer S.

2018-04-01

UV-POSIT (Ultraviolet Photodissociation Online Structure Interrogation Tools) is a suite of web-based tools designed to facilitate the rapid interpretation of data from native mass spectrometry experiments making use of 193 nm ultraviolet photodissociation (UVPD). The suite includes four separate utilities which assist in the calculation of fragment ion abundances as a function of backbone cleavage sites and sequence position; the localization of charge sites in intact proteins; the calculation of hydrogen elimination propensity for a-type fragment ions; and mass-offset searching of UVPD spectra to identify unknown modifications and assess false positive fragment identifications. UV-POSIT is implemented as a Python/Flask web application hosted at http://uv-posit.cm.utexas.edu. UV-POSIT is available under the MIT license, and the source code is available at https://github.com/jarosenb/UV_POSIT. [Figure not available: see fulltext.

UV-POSIT: Web-Based Tools for Rapid and Facile Structural Interpretation of Ultraviolet Photodissociation (UVPD) Mass Spectra.

PubMed

Rosenberg, Jake; Parker, W Ryan; Cammarata, Michael B; Brodbelt, Jennifer S

2018-06-01

UV-POSIT (Ultraviolet Photodissociation Online Structure Interrogation Tools) is a suite of web-based tools designed to facilitate the rapid interpretation of data from native mass spectrometry experiments making use of 193 nm ultraviolet photodissociation (UVPD). The suite includes four separate utilities which assist in the calculation of fragment ion abundances as a function of backbone cleavage sites and sequence position; the localization of charge sites in intact proteins; the calculation of hydrogen elimination propensity for a-type fragment ions; and mass-offset searching of UVPD spectra to identify unknown modifications and assess false positive fragment identifications. UV-POSIT is implemented as a Python/Flask web application hosted at http://uv-posit.cm.utexas.edu . UV-POSIT is available under the MIT license, and the source code is available at https://github.com/jarosenb/UV_POSIT . Graphical Abstract.

Experimental Evolution of UV-C Radiation Tolerance: Emergence of Adaptive and Non-Adaptive Traits in Escherichia coli Under Differing Flux Regimes

NASA Astrophysics Data System (ADS)

Moffet, A.; Okansinski, A.; Sloan, C.; Grace, J. M.; Paulino-Lima, I. G.; Gentry, D.; Rothschild, L. J.; Camps, M.

2014-12-01

High-energy ultraviolet (UV-C) radiation is a significant challenge to life in environments such as high altitude areas, the early Earth, the Martian surface, and space. As UV-C exposure is both a selection pressure and a mutagen, adaptation dynamics in such environments include a high rate of change in both tolerance-related and non-tolerance-related genes, as well changes in linkages between the resulting traits. Determining the relationship between the intensity and duration of the UV-C exposure, mutation rate, and emergence of UV-C resistance will inform our understanding of both the emergence of radiation-related extremophily in natural environments and the optimal strategies for generating artificial extremophiles. In this study, we iteratively exposed an Escherichia colistrain to UV-C radiation of two different fluxes, 3.3 J/m^2/s for 6 seconds and 0.5 J/m^2/s for 40 seconds, with the same overall fluence of 20 J/m^2. After each iteration, cells from each exposure regime were assayed for increased UV-C tolerance as an adaptive trait. The exposed cells carried a plasmid bearing a TEM beta-lactamase gene, which in the absence of antibiotic treatment is a neutral reporter for mutagenesis. Sequencing of this gene allowed us to determine the baseline mutation frequency for each flux. As an additional readout for adaptation, the presence of extended-spectrum beta-lactamase mutations was tested by plating UV-exposed cultures in cefotaxime plates. We observed an increase of approximately one-million-fold in UV-C tolerance over seven iterations; no significant difference between the two fluxes was found. Future work will focus on identifying the genomic changes responsible for the change in UV-C tolerance; determining the mechanisms of the emerged UV-C tolerance; and performing competition experiments between the iteration strains to quantify fitness tradeoffs resulting from UV-C adaptation.

Specificity in suppression of SOS expression by recA4162 and uvrD303

PubMed Central

Massoni, Shawn C.; Sandler, Steven J.

2013-01-01

Detection and repair of DNA damage is essential in all organisms and depends on the ability of proteins recognizing and processing specific DNA substrates. In E. coli, the RecA protein forms a filament on single-stranded DNA (ssDNA) produced by DNA damage and induces the SOS response. Previous work has shown that one type of recA mutation (e.g., recA4162 (I298V)) and one type of uvrD mutation (e.g., uvrD303 (D403A, D404A)) can differentially decrease SOS expression depending on the type of inducing treatments (UV damage versus RecA mutants that constitutively express SOS). Here it is tested using other SOS inducing conditions if there is a general feature of ssDNA generated during these treatments that allows recA4162 and uvrD303 to decrease SOS expression. The SOS inducing conditions tested include growing cells containing temperature-sensitive DNA replication mutations (dnaE486, dnaG2903, dnaN159, dnaZ2016 (at 37°C)), a del(polA)501 mutation and induction of Double-Strand Breaks (DSBs). uvrD303 could decrease SOS expression under all conditions, while recA4162 could decrease SOS expression under all conditions except in the polA strain or when DSBs occur. It is hypothesized that recA4162 suppresses SOS expression best when the ssDNA occurs at a gap and that uvrD303 is able to decrease SOS expression when the ssDNA is either at a gap or when it is generated at a DSB (but does so better at a gap). PMID:24084169

Specificity in suppression of SOS expression by recA4162 and uvrD303.

PubMed

Massoni, Shawn C; Sandler, Steven J

2013-12-01

Detection and repair of DNA damage is essential in all organisms and depends on the ability of proteins recognizing and processing specific DNA substrates. In E. coli, the RecA protein forms a filament on single-stranded DNA (ssDNA) produced by DNA damage and induces the SOS response. Previous work has shown that one type of recA mutation (e.g., recA4162 (I298V)) and one type of uvrD mutation (e.g., uvrD303 (D403A, D404A)) can differentially decrease SOS expression depending on the type of inducing treatments (UV damage versus RecA mutants that constitutively express SOS). Here it is tested using other SOS inducing conditions if there is a general feature of ssDNA generated during these treatments that allows recA4162 and uvrD303 to decrease SOS expression. The SOS inducing conditions tested include growing cells containing temperature-sensitive DNA replication mutations (dnaE486, dnaG2903, dnaN159, dnaZ2016 (at 37°C)), a del(polA)501 mutation and induction of Double-Strand Breaks (DSBs). uvrD303 could decrease SOS expression under all conditions, while recA4162 could decrease SOS expression under all conditions except in the polA strain or when DSBs occur. It is hypothesized that recA4162 suppresses SOS expression best when the ssDNA occurs at a gap and that uvrD303 is able to decrease SOS expression when the ssDNA is either at a gap or when it is generated at a DSB (but does so better at a gap). Copyright © 2013 Elsevier B.V. All rights reserved.

Unexpected solvent effects on the UV/Vis absorption spectra of o-cresol in toluene and benzene: in contrast with non-aromatic solvents

PubMed Central

Zheng, Dong; Yuan, Xiang-Ai; Ma, Haibo; Li, Xiaoxiong; Wang, Xizhang; Liu, Ziteng

2018-01-01

Cresol is a prototype molecule in understanding intermolecular interactions in material and biological systems, because it offers different binding sites with various solvents and protonation states under different pH values. It is found that the UV/Vis absorption spectra of o-cresol in aromatic solvents (benzene, toluene) are characterized by a sharp peak, unlike the broad double-peaks in 11 non-aromatic solvents. Both molecular dynamics simulations and electronic structure calculations revealed the formation of intermolecular π-complexation between o-cresol and aromatic solvents. The thermal movements of solvent and solute molecules render the conformations of o-cresol changing between trans and cis isomers. The π-interaction makes the cis configuration a dominant isomer, hence leading to the single keen-edged UV/Vis absorption peak at approximately 283 nm. The free conformation changes between trans and cis in aqueous solution rationalize the broader absorption peaks in the range of 260–280 nm. The pH dependence of the UV/Vis absorption spectra in aqueous solutions is also rationalized by different protonation states of o-cresol. The explicit solvent model with long-ranged interactions is vital to describe the effects of π-complexation and electrostatic interaction on the UV/Vis absorption spectra of o-cresol in toluene and alkaline aqueous (pH > 10.3) solutions, respectively. PMID:29657794

Unexpected solvent effects on the UV/Vis absorption spectra of o-cresol in toluene and benzene: in contrast with non-aromatic solvents.

PubMed

Zheng, Dong; Yuan, Xiang-Ai; Ma, Haibo; Li, Xiaoxiong; Wang, Xizhang; Liu, Ziteng; Ma, Jing

2018-03-01

Cresol is a prototype molecule in understanding intermolecular interactions in material and biological systems, because it offers different binding sites with various solvents and protonation states under different pH values. It is found that the UV/Vis absorption spectra of o -cresol in aromatic solvents (benzene, toluene) are characterized by a sharp peak, unlike the broad double-peaks in 11 non-aromatic solvents. Both molecular dynamics simulations and electronic structure calculations revealed the formation of intermolecular π-complexation between o -cresol and aromatic solvents. The thermal movements of solvent and solute molecules render the conformations of o -cresol changing between trans and cis isomers. The π-interaction makes the cis configuration a dominant isomer, hence leading to the single keen-edged UV/Vis absorption peak at approximately 283 nm. The free conformation changes between trans and cis in aqueous solution rationalize the broader absorption peaks in the range of 260-280 nm. The pH dependence of the UV/Vis absorption spectra in aqueous solutions is also rationalized by different protonation states of o -cresol. The explicit solvent model with long-ranged interactions is vital to describe the effects of π-complexation and electrostatic interaction on the UV/Vis absorption spectra of o -cresol in toluene and alkaline aqueous (pH > 10.3) solutions, respectively.

Single photon infrared emission spectroscopy: a study of IR emission from UV laser excited PAHs between 3 and 15 micrometers

NASA Technical Reports Server (NTRS)

Cook, D. J.; Schlemmer, S.; Balucani, N.; Wagner, D. R.; Harrison, J. A.; Steiner, B.; Saykally, R. J.

1998-01-01

Single-photon infrared emission spectroscopy (SPIRES) has been used to measure emission spectra from polycyclic aromatic hydrocarbons (PAHs). A supersonic free-jet expansion has been used to provide emission spectra of rotationally cold and vibrationally excited naphthalene and benzene. Under these conditions, the observed width of the 3.3-micrometers (C-H stretch) band resembles the bandwidths observed in experiments in which emission is observed from naphthalene with higher rotational energy. To obtain complete coverage of IR wavelengths relevant to the unidentified infrared bands (UIRs), UV laser-induced desorption was used to generate gas-phase highly excited PAHs. Lorentzian band shapes were convoluted with the monochromator-slit function in order to determine the widths of PAH emission bands under astrophysically relevant conditions. Bandwidths were also extracted from bands consisting of multiple normal modes blended together. These parameters are grouped according to the functional groups mostly involved in the vibration, and mean bandwidths are obtained. These bandwidths are larger than the widths of the corresponding UIR bands. However, when the comparison is limited to the largest PAHs studied, the bandwidths are slightly smaller than the corresponding UIR bands. These parameters can be used to model emission spectra from PAH cations and cations of larger PAHs, which are better candidate carriers of the UIRs.

Experimental and theoretical study on emission spectra of a nitrogen photoionized plasma induced by intense EUV pulses

NASA Astrophysics Data System (ADS)

Saber, Ismail; Bartnik, Andrzej; Skrzeczanowski, Wojciech; Wachulak, Przemyslaw; Jarocki, Roman; Fiedorowicz, Henryk; Limpouch, Jiri

2018-01-01

Spectral lines of low-temperature nitrogen photoionized plasma were investigated. The photoionized plasma was created in the result of irradiation N2 gas using laser plasma EUV radiation pulses. The source was based on a 10J/10ns Nd:YAG (λ = 1064 nm) laser system and a gas puff target. The EUV radiation pulses were collected and focused using a grazing incidence multifoil EUV collector. The emission spectra were measured in the ultraviolet and visible (UV/Vis) range. It was found that the plasma emission lines in the lower region of the UV range are relativley weak. Nonetheless, a part of the spectra contains strong molecular band in the 300 - 430 nm originated from second positive and first negative systems band transitions of nitrogen. These molecular band transitions were identified using a code for study the diatomic molecules, LIFBASE. The vibrational band of Δv = 0 and ±1 transitions were significantly populated than of that with Δv = ±2 and 3 transitions. A comparison of the calculated and measured spectrum is presented. With an assumption of a local thermodynamic equilibrium (LTE), the vibrational temperature was determined from the integrated band intensities with the help of the Boltzmann plot method and compared to the temperature predicted by SPECAIR and LIFBASE simulations. A summary of the results and the variations in the vibrational temperatures was discussed.

Optical study of gamma irradiated sodium metaphosphate glasses containing divalent metal oxide MO (ZnO or CdO)

NASA Astrophysics Data System (ADS)

Nabhan, E.; Abd-Allah, W. M.; Ezz-El-Din, F. M.

Sodium metaphosphate glasses containing divalent metal oxide, ZnO or CdO with composition 50 P2O5 - (50 - x) Na2O - x MO (ZnO, or CdO) where x = 0, 10, 20 (mol%) were prepared by conventional melt method. UV/visible spectroscopy and FTIR spectroscopy are measured before and after exposing to successive gamma irradiation doses (5-80 kGy). The optical absorption spectra results of the samples before irradiation reveal a strong UV absorption band at (∼230 nm) which is related to unavoided iron impurities. The effects of gamma irradiation on the optical spectral properties of the various glasses have been compared. From the optical absorption spectral data, the optical band gap is evaluated. The main structural groups and the influence of both divalent metal oxide and gamma irradiation effect on the structural vibrational groups are realized through IR spectroscopy. The FTIR spectra of γ-irradiated samples are characterized by the stability of the number and position for the main characteristic band of phosphate groups. To better understood the structural changes during γ-irradiation, a deconvolution of FTIR spectra in the range 650-1450 cm-1 is made. The FTIR deconvolution results found evidence that, the changes occurring after gamma irradiation have been related to irradiation induced structural defects and compositional changes.

Epidermal PPARγ influences subcutaneous tumor growth and acts through TNF-α to regulate contact hypersensitivity and the acute photoresponse

PubMed Central

Konger, Raymond L.; Derr-Yellin, Ethel; Travers, Jeffrey B.; Ocana, Jesus A.; Sahu, Ravi P.

2017-01-01

It is known that ultraviolet B (UVB) induces PPARγ ligand formation while loss of murine epidermal PPARγ (Pparg-/-epi) promotes UVB-induced apoptosis, inflammation, and carcinogenesis. PPARγ is known to suppress tumor necrosis factor-α (TNF-α) production. TNF-α is also known to promote UVB-induced inflammation, apoptosis, and immunosuppression. We show that Pparg-/-epi mice exhibit increased baseline TNF-α expression. Neutralizing Abs to TNF-α block the increased photo-inflammation and photo-toxicity that is observed in Pparg-/-epi mouse skin. Interestingly, the increase in UVB-induced apoptosis in Pparg-/-epi mice is not accompanied by a change in cyclobutane pyrimidine dimer clearance or in mutation burden. This suggests that loss of epidermal PPARγ does not result in a significant alteration in DNA repair capacity. However, loss of epidermal PPARγ results in marked immunosuppression using a contact hypersensitivity (CHS) model. This impaired CHS response was significantly alleviated using neutralizing TNF-α antibodies or loss of germline Tnf. In addition, the PPARγ agonist rosiglitazone reversed UVB-induced systemic immunosuppression (UV-IS) as well as UV-induced growth of B16F10 melanoma tumor cells in syngeneic mice. Finally, increased B16F10 tumor growth was observed when injected subcutaneously into Pparg-/-epi mice. Thus, we provide novel evidence that epidermal PPARγ is important for cutaneous immune function and the acute photoresponse. PMID:29228682

Photosynthetic benefits of ultraviolet-A to Pimelea ligustrina, a woody shrub of sub-alpine Australia.

PubMed

Turnbull, Tarryn L; Barlow, Alexandra M; Adams, Mark A

2013-10-01

The definition of photosynthetically active radiation (Q) as the visible waveband (λ 400-700 nm) is a core assumption of much of modern plant biology and global models of carbon and water fluxes. On the other hand, much research has focused on potential mutation and damage to leaves caused by ultraviolet (UV) radiation (280-400 nm), and anatomical and physiological adaptations that help avoid such damage. Even so, plant responses to UV-A are poorly described and, until now, photosynthetic utilization of UV-A has not been elucidated under full light conditions in the field. We found that the UV-A content of sunlight increased photosynthetic rates in situ by 12% in Pimelea ligustrina Labill., a common and indigenous woody shrub of alpine ecosystems of the Southern Hemisphere. Compared to companion shrubs, UV-A-induced photosynthesis in P. ligustrina resulted from reduced physical and chemical capacities to screen UV-A at the leaf surface (illustrated by a lack of cuticle and reduced phenol index) and the resulting ability of UV-A to excite chlorophyll (Chl) a directly, and via energy provided by the carotenoid lutein. A screening of 55 additional sub-alpine species showed that 47% of the plant taxa also display Chl a fluorescence under UV-A. If Chl a fluorescence indicates potential for photosynthetic gain, continued exclusion of UV-A from definitions of Q in this ecosystem could result in underestimates of measured and modeled rates of photosynthesis and miscalculation of potential for carbon sequestration. We suggest that carbon gain for alpine environs across the globe could be similarly underestimated given that UV-A radiation increases with altitude and that the frequently dominant herb and grass life-forms often transmit UV-A through the epidermis.

UV-Vis Action Spectroscopy Reveals a Conformational Collapse in Hydrogen-Rich Dinucleotide Cation Radicals.

PubMed

Korn, Joseph A; Urban, Jan; Dang, Andy; Nguyen, Huong T H; Tureček, František

2017-09-07

We report the generation of deoxyriboadenosine dinucleotide cation radicals by gas-phase electron transfer to dinucleotide dications and their noncovalent complexes with crown ether ligands. Stable dinucleotide cation radicals of a novel hydrogen-rich type were generated and characterized by tandem mass spectrometry and UV-vis photodissociation (UVPD) action spectroscopy. Electron structure theory analysis indicated that upon electron attachment the dinucleotide dications underwent a conformational collapse followed by intramolecular proton migrations between the nucleobases to give species whose calculated UV-vis absorption spectra matched the UVPD action spectra. Hydrogen-rich cation radicals generated from chimeric riboadenosine 5'-diesters gave UVPD action spectra that pointed to novel zwitterionic structures consisting of aromatic π-electron anion radicals intercalated between stacked positively charged adenine rings. Analogies with DNA ionization are discussed.

Space Telescope and Optical Reverberation Mapping Project VI. Variations of the Intrinsic Absorption Lines in NGC 5548

NASA Astrophysics Data System (ADS)

Kriss, Gerard A.; Agn Storm Team

2015-01-01

The AGN STORM collaboration monitored the Seyfert 1 galaxy NGC 5548 over a six-month period, with observations spanning the hard X-ray to mid-infrared wavebands. The core of this campaign was an intensive HST COS program, which obtained 170 far-ultraviolet spectra at approximately daily intervals, with twice-per-day monitoring of the X-ray, near-UV, and optical bands during much of the same period using Swift. The broad UV absorption lines discovered by Kaastra et al. (2014) and associated with the new soft X-ray obscurer are continuously present in the STORM campaign COS spectra. Their strength varies with the degree of soft X-ray obscuration as revealed by the Swift X-ray spectra. The narrow associated absorption lines in the UV spectrum of NGC 5548 remain strong. The lower-ionization transitions that appeared concurrently with the soft X-ray obscuration vary in response to the changing UV flux on a daily basis. Their depths over the longer term, however, also respond to the strength of the soft X-ray obscuration, indicating that the soft X-ray obscurer has a significant influence on the ionizing UV continuum that is not directly tracked by the observable UV continuum itself.

Forecasting of UV-Vis absorbance time series using artificial neural networks combined with principal component analysis.

PubMed

Plazas-Nossa, Leonardo; Hofer, Thomas; Gruber, Günter; Torres, Andres

2017-02-01

This work proposes a methodology for the forecasting of online water quality data provided by UV-Vis spectrometry. Therefore, a combination of principal component analysis (PCA) to reduce the dimensionality of a data set and artificial neural networks (ANNs) for forecasting purposes was used. The results obtained were compared with those obtained by using discrete Fourier transform (DFT). The proposed methodology was applied to four absorbance time series data sets composed by a total number of 5705 UV-Vis spectra. Absolute percentage errors obtained by applying the proposed PCA/ANN methodology vary between 10% and 13% for all four study sites. In general terms, the results obtained were hardly generalizable, as they appeared to be highly dependent on specific dynamics of the water system; however, some trends can be outlined. PCA/ANN methodology gives better results than PCA/DFT forecasting procedure by using a specific spectra range for the following conditions: (i) for Salitre wastewater treatment plant (WWTP) (first hour) and Graz West R05 (first 18 min), from the last part of UV range to all visible range; (ii) for Gibraltar pumping station (first 6 min) for all UV-Vis absorbance spectra; and (iii) for San Fernando WWTP (first 24 min) for all of UV range to middle part of visible range.

Diagnostic spectroscopic and computer-aided evaluation of malignancy from UV/VIS spectra of clear pleural effusions

NASA Astrophysics Data System (ADS)

Jevtić, Dubravka R.; Avramov Ivić, Milka L.; Reljin, Irini S.; Reljin, Branimir D.; Plavec, Goran I.; Petrović, Slobodan D.; Mijin, Dušan Ž.

2014-06-01

The automated, computer-aided method for differentiation and classification of malignant (M) from benign (B) cases, by analyzing the UV/VIS spectra of pleural effusions is described. It was shown that by two independent objective features, the maximum of Katz fractal dimension (KFDmax) and the area under normalized UV/VIS absorbance curve (Area), highly reliable M-B classification is possible. In the Area-KFDmax space M and B samples are linearly separable permitting thus the use of linear support vector machine as a classification tool. By analyzing 104 samples of UV/VIS spectra of pleural effusions (88 M and 16 B) collected from patients at the Clinic for Lung Diseases and Tuberculosis, Military Medical Academy in Belgrade, the accuracy of 95.45% for M cases and 100% for B cases are obtained by using the proposed method. It was shown that by applying some modifications, which are suggested in the paper, the accuracy of 100% for M cases can be reached.

Protonation effects on the UV/Vis absorption spectra of imatinib: a theoretical and experimental study.

PubMed

Grante, Ilze; Actins, Andris; Orola, Liana

2014-08-14

An experimental and theoretical investigation of protonation effects on the UV/Vis absorption spectra of imatinib showed systematic changes of absorption depending on the pH, and a new absorption band appeared below pH 2. These changes in the UV/Vis absorption spectra were interpreted using quantum chemical calculations. The geometry of various imatinib cations in the gas phase and in ethanol solution was optimized with the DFT/B3LYP method. The resultant geometries were compared to the experimentally determined crystal structures of imatinib salts. The semi-empirical ZINDO-CI method was employed to calculate the absorption lines and electronic transitions. Our study suggests that the formation of the extra near-UV absorption band resulted from an increase of imatinib trication concentration in the solution, while the rapid increase of the first absorption maximum could be attributed to both the formation of imatinib trication and tetracation. Copyright © 2014 Elsevier B.V. All rights reserved.

Archival Study of Energetic Processes in the Upper Atmosphere of the Outer Planets

NASA Technical Reports Server (NTRS)

Ballester, Gilda E.; Harris, Walter M.

1998-01-01

We compare International Ultraviolet Explorer (IUE) spectral observations of Jupiter's UltraViolet (UV) aurora in H-Lyman alpha (H-Lya) and H2 emissions with images of the UV aurora with HST to make more realistic interpretations of the IUE dataset. Use the limited spatial information in the IUE line-by-line spectra of the bright H-Lya line emission in the form of pseudo-monochromatic images at the IUE 3.5 arcsec resolution (Lya pseudo-images), to derive information on the emissions. Analysing of H2 spectra of Saturn's UV aurora to infer atmospheric level of auroral excitation from the methane absorption (color ratios). Analysing of a Uranus IUE dataset to determine periodicity in the emissions attributable to auroral emission fixed in magnetic longitude. Reviewing of the results from IUE observations of the major planets, upper atmospheres and interactions with the planets magnetospheres. Analysing of IUE spectra of the UV emissions from Io to identify excitation processes and infer properties of the Io-torus-Jupiter system.

UV EFFECTS IN TOOTH ENAMEL AND THEIR POSSIBLE APPLICATION IN EPR DOSIMETRY WITH FRONT TEETH

PubMed Central

Sholom, S.; Desrosiers, M.; Chumak, V.; Luckyanov, N.; Simon, S.L.; Bouville, A.

2009-01-01

The effects of ultraviolet (UV) radiation on ionizing radiation biodosimetry were studied in human tooth enamel samples using the technique of electron paramagnetic resonance (EPR) in X-band. For samples in the form of grains, UV-specific EPR spectra were spectrally distinct from that produced by exposure to gamma radiation. From larger enamel samples, the UV penetration depth was determined to be in the 60–120 μm range. The difference in EPR spectra from UV exposure and from exposure to gamma radiation samples was found to be a useful marker of UV equivalent dose (defined as the apparent contribution to the gamma dose in mGy that results from UV radiation absorption) in tooth enamel. This concept was preliminarily tested on front teeth from inhabitants of the region of the Semipalatinsk Nuclear Test Site (Kazakhstan) who might have received some exposure to gamma radiation from the nuclear tests conducted there as well as from normal UV radiation in sunlight. The technique developed here to quantify and subtract the UV contribution to the measured tooth is currently limited to cumulative dose measurements with a component of UV equivalent dose equal to or greater than 300 mGy. PMID:20065706

Variables that influence BRAF mutation probability: A next-generation sequencing, non-interventional investigation of BRAFV600 mutation status in melanoma.

PubMed

Gaiser, Maria Rita; Skorokhod, Alexander; Gransheier, Diana; Weide, Benjamin; Koch, Winfried; Schif, Birgit; Enk, Alexander; Garbe, Claus; Bauer, Jürgen

2017-01-01

The incidence of melanoma, particularly in older patients, has steadily increased over the past few decades. Activating mutations of BRAF, the majority occurring in BRAFV600, are frequently detected in melanoma; however, the prognostic significance remains unclear. This study aimed to define the probability and distribution of BRAFV600 mutations, and the clinico-pathological factors that may affect BRAF mutation status, in patients with advanced melanoma using next-generation sequencing. This was a non-interventional, retrospective study of BRAF mutation testing at two German centers, in Heidelberg and Tübingen. Archival tumor samples from patients with histologically confirmed melanoma (stage IIIB, IIIC, IV) were analyzed using PCR amplification and deep sequencing. Clinical, histological, and mutation data were collected. The statistical influence of patient- and tumor-related characteristics on BRAFV600 mutation status was assessed using multiple logistic regression (MLR) and a prediction profiler. BRAFV600 mutation status was assessed in 453 samples. Mutations were detected in 57.6% of patients (n = 261), with 48.1% (n = 102) at the Heidelberg site and 66.0% (n = 159) at the Tübingen site. The decreasing influence of increasing age on mutation probability was quantified. A main effects MLR model identified age (p = 0.0001), center (p = 0.0004), and melanoma subtype (p = 0.014) as significantly influencing BRAFV600 mutation probability; ultraviolet (UV) exposure showed a statistical trend (p = 0.1419). An interaction model of age versus other variables showed that center (p<0.0001) and melanoma subtype (p = 0.0038) significantly influenced BRAF mutation probability; age had a statistically significant effect only as part of an interaction with both UV exposure (p = 0.0110) and melanoma subtype (p = 0.0134). This exploratory study highlights that testing center, melanoma subtype, and age in combination with UV exposure and melanoma subtype significantly influence BRAFV600 mutation probability in patients with melanoma. Further validation of this model, in terms of reproducibility and broader relevance, is required.

Damage induced in garnets by heavy ion irradiations: a study by optical spectroscopies

NASA Astrophysics Data System (ADS)

Costantini, Jean-Marc; Miro, Sandrine; Lelong, Gérald; Guillaumet, Maxime; Toulemonde, Marcel

2018-02-01

The damage induced by heavy-ion irradiation has been studied in yttrium iron garnet (Y3Fe5O12 or YIG) films, doped with Ca, Tb and Tm, grown by liquid-phase epitaxy on gadolinium gallium garnet (Gd3Ga5O12 or GGG) substrates. Irradiations of doped-YIG epitaxial films and GGG substrates with 36-MeV 183W and 12-MeV 197Au ions were applied for fluences between 1 × 1013 and 3 × 1015 cm-2 near room temperature. The radiation damage was monitored by micro-Raman spectroscopy and UV-visible optical absorption spectroscopy. Raman spectra revealed that amorphisation was achieved in YIG for both ions, whereas a high lattice disorder was induced in GGG without reaching amorphisation for the Au ion irradiation. Raman spectra also showed that a major damage of the tetrahedral sites was induced in GGG, as previously found for YIG. It is concluded that with such ions reaching the stopping power threshold of track formation in YIG and GGG the observed rate of amorphisation may result from a combination of electronic and nuclear energy losses as calculated using the unified thermal spike model.

VizieR Online Data Catalog: Radial velocities of the Be star HR 2142 (Peters+, 2016)

NASA Astrophysics Data System (ADS)

Peters, G. J.; Wang, L.; Gies, D. R.; Grundstrom, E. D.

2016-11-01

Radial velocity measurements were made using the set of spectra summarized in Table 1. The main focus of this work is a set of 88 high resolution, SWP HIRES FUV spectra acquired over the lifetime of the International Ultraviolet Explorer (IUE) observatory. These were downloaded from MAST and resampled. We also collected a set of 49 LWR and LWP near-UV spectra that were used to inspect the orbital variations in the MgII2796,2803 feature. The UV spectra were supplemented with a large collection of Hα spectra that we secured with the KPNO Coude Feed telescope and that were obtained by amateur astronomers participating in the Be Star Spectra database project (Pollmann 2007IBVS.5778....1P; Neiner et al. 2011AJ....142..149N). (2 data files).

Raman spectroscopy of white wines.

PubMed

Martin, Coralie; Bruneel, Jean-Luc; Guyon, François; Médina, Bernard; Jourdes, Michael; Teissedre, Pierre-Louis; Guillaume, François

2015-08-15

The feasibility of exploiting Raman scattering to analyze white wines has been investigated using 3 different wavelengths of the incoming laser radiation in the near-UV (325 nm), visible (532 nm) and near infrared (785 nm). To help in the interpretation of the Raman spectra, the absorption properties in the UV-visible range of two wine samples as well as their laser induced fluorescence have also been investigated. Thanks to the strong intensity enhancement of the Raman scattered light due to electronic resonance with 325 nm laser excitation, hydroxycinnamic acids may be detected and analyzed selectively. Fructose and glucose may also be easily detected below ca. 1000 cm(-1). This feasibility study demonstrates the potential of the Raman spectroscopic technique for the analysis of white wines. Copyright © 2015 Elsevier Ltd. All rights reserved.

Xeroderma pigmentosum: diagnostic procedures, interdisciplinary patient care, and novel therapeutic approaches.

PubMed

Lehmann, Janin; Schubert, Steffen; Emmert, Steffen

2014-10-01

Xeroderma pigmentosum (XP) is an autosomal recessive disease, caused by a gene defect in the nucleotide-excision-repair (NER) pathway or in translesional DNA synthesis. At the age of eight, patients already develop their first skin cancers due to this DNA repair defect. In contrast, in the Caucasian population the first tumor formation in UV exposed skin regions occurs at a mean age of 60. The clinical picture among patients suffering from XP is highly diverse and includes signs of accelerated skin aging, and UV-induced skin cancers, as well as ophthalmologic and neurological symptoms. Patients should therefore receive interdisciplinary care. This includes dermatologists, ophthalmologists, ENT specialists, neurologists, and human geneticists. Patients with XP are clinically diagnosed, but this may be supported by molecular-genetic and functional analyses. These analyses allow pinpointing the exact disease-causing gene defect (complementation group assignment, detection of the type and location of the mutation within the gene). The resulting information is already relevant to predict the course of disease and symptoms and probably will be utilized for individualized therapeutic approaches in the future. Recently, enhanced repair of UV photolesions in xeroderma pigmentosum group C cells induced by translational readthrough of premature termination codons by certain antibiotics could be demonstrated. © 2014 Deutsche Dermatologische Gesellschaft (DDG). Published by John Wiley & Sons Ltd.

Airborne remote sensing of ultraviolet-absorbing aerosols during the NASA ATom, SEAC4RS and DC3 campaigns

NASA Astrophysics Data System (ADS)

Hall, S. R.; Ullmann, K.; Commane, R.; Crounse, J. D.; Daube, B. C.; Diskin, G. S.; Dollner, M.; Froyd, K. D.; Katich, J. M.; Kim, M. J.; Madronich, S.; Murphy, D. M.; Podolske, J. R.; Schwarz, J. P.; Teng, A.; Weber, R. J.; Weinzierl, B.; Wennberg, P. O.; Sachse, G.; Wofsy, S.

2017-12-01

Spectrally resolved up and down-welling actinic flux was measured from the NASA DC-8 aircraft by the Charged-coupled device Actinic Flux Spectroradiometers (CAFS) during recent campaigns including ATom, DC3 and SEAC4RS. The primary purpose is retrieval of 40 photolysis frequencies to complement the in situ chemistry. However, the spectra also provide the opportunity to examine absorption trends in the UV where few other measurements exist. In particular, absorption by brown (BrC) and black (BC) carbon aerosols result in characteristic UV signatures. A new technique exploits the spectral changes to detect the presence of these aerosols for qualitative, real-time, remote sensing of biomass burning (BB). The data may prove useful for examination of the evolution of BrC, including chemical processing and hygroscopic growth. The induced UV changes also feed back to the photolysis frequencies affecting the chemistry. Further work will determine the robustness of the technique and if quantitative spectral absorption retrievals are possible.

Mutants of Agrobacterium tumefaciens with elevated vir gene expression

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pazour, G.J.; Ta, C.N.; Das, A.

1991-08-15

Expression of Agrobacterium tumefaciens virulence (vir) genes requires virA, virG, and a plant-derived inducing compound such as acetosyringone. To identify the critical functional domains of virA and virG, a mutational approach was used. Agrobacterium A136 harboring plasmid pGP159, which contains virA, virG, and a reporter virB:lacZ gene fusion, was mutagenized with UV light or nitrosoguanidine. Survivors that formed blue colonies on a plate containing 5-bromo-4-chloro-3-indolyl beta-D-galactoside were isolated and analyzed. Quantification of beta-galactosidase activity in liquid assays identified nine mutant strains. By plasmid reconstruction and other procedures, all mutations mapped to the virA locus. These mutations caused an 11- tomore » 560-fold increase in the vegetative level of virB:lacZ reporter gene expression. DNA sequence analysis showed that the mutations are located in four regions of VirA: transmembrane domain one, the active site, a glycine-rich region with homology to ATP-binding sites, and a region at the C terminus that has homology to the N terminus of VirG.« less

Indications for an inducible component of error-prone DNA repair in yeast.

PubMed

Siede, W; Eckardt, F

1984-01-01

In a thermoconditional mutant of mutagenic DNA repair (rev 2ts = rad 5-8) of Saccharomyces cerevisiae recovery of survival and mutation frequencies can be monitored by incubating UV-irradiated cells in growth medium at a permissive temperature (23 degrees C) before plating and a shift to restrictive temperature (36 degrees C). Inhibition of protein synthesis with cycloheximide during incubation at permissive conditions blocks this REV 2 dependent recovery process in stationary phase rev 2ts cells, whereas it can be reduced but not totally abolished in exponentially growing cells. These results indicate a strict dependence on post-irradiation protein synthesis in stationary phase cells and argue for a considerable constitutive level and only limited inducibility in logarithmic phase cells. The UV inducibility of the REV 2 coded function in stationary phase cells could be confirmed by analysis of the dose-response pattern of the his 5-2 reversion: in stationary phase rev 2ts cells, the quadratic component of the biphasic linear-quadratic induction kinetics found at 23 degrees C, which is interpreted as the consequence of induction of mutagenic repair, is eliminated at 36 degrees C.

Calculation of UV, IR, and NMR Spectra of Diethyl 2,2'-[(1,1'-Biphenyl)-4,4'-Diylbis(Azanediyl)]Diacetate

NASA Astrophysics Data System (ADS)

Almodarresiyeh, H. A.; Shahab, S. N.; Zelenkovsky, V. M.; Ariko, N. G.; Filippovich, L. N.; Agabekov, V. E.

2014-03-01

The new substance diethyl 2,2'-[(1,1'-biphenyl)-4,4'-diylbis(azanediyl)]diacetate (M13) was modeled using the Hartree-Fock and density functional theory methods and then synthesized. The electronic absorption spectrum of M13 in dimethylformamide solution was calculated. The UV, IR, and NMR spectra of M13 were presented.

Application of Independent Component Analysis to Legacy UV Quasar Spectra

NASA Astrophysics Data System (ADS)

Richards, Gordon

2017-08-01

We propose to apply a novel analysis technique to UV spectroscopy ofquasars in the HST archive. We endeavor to analyze all of thearchival quasar spectra, but will first focus on those quasars thatalso have optical spectroscopy from SDSS. An archival investigationby Sulentic et al. (2007) revealed 130 known quasars with UV coverageof CIV complementing optical emission line coverage. Today, thesample has grown considerably and now includes COS spectroscopy. Ourproposal includes a proof-of-concept demonstration of the power of atechnique called Independent Component Analysis (ICA). ICA allows usto reduce complexity of of quasar spectra to just a handful ofnumbers. In addition to providing a uniform set of traditional linemeasurements (and carefully calibrated redshifts), we will provide ICAweights to the community with examples of how they can be used to doscience that previously would have been quite difficult. The time isripe for such an investigation because 1) it has been a decade sincethe last significant archival investigation of UV emission lines fromHST quasars, 2) the future is uncertain for obtaining new UV quasarspectroscopy, and 3) the rise of machine learning has provided us withpowerful new tools. Thus our proposed work will provide a true UVlegacy database for quasar-based investigations.

Ultraviolet stress delays chromosome replication in light/dark synchronized cells of the marine cyanobacterium Prochlorococcus marinus PCC9511

PubMed Central

2010-01-01

Background The marine cyanobacterium Prochlorococcus is very abundant in warm, nutrient-poor oceanic areas. The upper mixed layer of oceans is populated by high light-adapted Prochlorococcus ecotypes, which despite their tiny genome (~1.7 Mb) seem to have developed efficient strategies to cope with stressful levels of photosynthetically active and ultraviolet (UV) radiation. At a molecular level, little is known yet about how such minimalist microorganisms manage to sustain high growth rates and avoid potentially detrimental, UV-induced mutations to their DNA. To address this question, we studied the cell cycle dynamics of P. marinus PCC9511 cells grown under high fluxes of visible light in the presence or absence of UV radiation. Near natural light-dark cycles of both light sources were obtained using a custom-designed illumination system (cyclostat). Expression patterns of key DNA synthesis and repair, cell division, and clock genes were analyzed in order to decipher molecular mechanisms of adaptation to UV radiation. Results The cell cycle of P. marinus PCC9511 was strongly synchronized by the day-night cycle. The most conspicuous response of cells to UV radiation was a delay in chromosome replication, with a peak of DNA synthesis shifted about 2 h into the dark period. This delay was seemingly linked to a strong downregulation of genes governing DNA replication (dnaA) and cell division (ftsZ, sepF), whereas most genes involved in DNA repair (such as recA, phrA, uvrA, ruvC, umuC) were already activated under high visible light and their expression levels were only slightly affected by additional UV exposure. Conclusions Prochlorococcus cells modified the timing of the S phase in response to UV exposure, therefore reducing the risk that mutations would occur during this particularly sensitive stage of the cell cycle. We identified several possible explanations for the observed timeshift. Among these, the sharp decrease in transcript levels of the dnaA gene, encoding the DNA replication initiator protein, is sufficient by itself to explain this response, since DNA synthesis starts only when the cellular concentration of DnaA reaches a critical threshold. However, the observed response likely results from a more complex combination of UV-altered biological processes. PMID:20670397

Model Atmospheres and Spectral Irradiance Library of the Exoplanet Host Stars Observed in the MUSCLES Survey

NASA Astrophysics Data System (ADS)

Linsky, Jeffrey

2017-08-01

We propose to compute state-of-the-art model atmospheres (photospheres, chromospheres, transition regions and coronae) of the 4 K and 7 M exoplanet host stars observed by HST in the MUSCLES Treasury Survey, the nearest host star Proxima Centauri, and TRAPPIST-1. Our semi-empirical models will fit theunique high-resolution panchromatic (X-ray to infrared) spectra of these stars in the MAST High-Level Science Products archive consisting of COS and STIS UV spectra and near-simultaneous Chandra, XMM-Newton, and ground-based observations. We will compute models with the fully tested SSRPM computer software incorporating 52 atoms and ions in full non-LTE (435,986 spectral lines) and the 20 most-abundant diatomic molecules (about 2 million lines). This code has successfully fit the panchromatic spectrum of the M1.5 V exoplanet host star GJ 832 (Fontenla et al. 2016), the first M star with such a detailed model, and solar spectra. Our models will (1) predict the unobservable extreme-UV spectra, (2) determine radiative energy losses and balancing heating rates throughout these atmospheres, (3) compute a stellar irradiance library needed to describe the radiation environment of potentially habitable exoplanets to be studied by TESS and JWST, and (4) in the long post-HST era when UV observations will not be possible, the stellar irradiance library will be a powerful tool for predicting the panchromatic spectra of host stars that have only limited spectral coverage, in particular no UV spectra. The stellar models and spectral irradiance library will be placed quickly in MAST.

Molecular spectroscopic studies of lichen substances 1: parietin and emodin

NASA Astrophysics Data System (ADS)

Edwards, Howell G. M.; Newton, Emma M.; Wynn-Williams, David D.; Coombes, Steven R.

2003-03-01

The Raman and infrared spectra of the UV-radiation protectant parietin extracted from Xanthoria lichen species are reported and vibrational assignments made of key features which are important for the characterisation of parietin in situ in stress-tolerant living organisms. The spectra of parietin are compared with those of the chemically related emodin, which is of pharmaceutical interest. The key molecular vibrational bands of parietin will be used for the analysis of lichen specimens exposed to high UV-radiation stress growing on Leonie Island, Antarctica, under the 'ozone hole' to better understand the production of UV-protectants in controlled habitats.

Sensitivity of human cells expressing low-fidelity or weak-catalytic-activity variants of DNA polymerase ζ to genotoxic stresses.

PubMed

Suzuki, Tetsuya; Grúz, Petr; Honma, Masamitsu; Adachi, Noritaka; Nohmi, Takehiko

2016-09-01

Translesion DNA polymerases (TLS pols) play critical roles in defense mechanisms against genotoxic agents. The defects or mutations of TLS pols are predicted to result in hypersensitivity of cells to environmental mutagens. In this study, human cells expressing DNA polymerase ζ (Pol ζ) variants with low fidelity or weak catalytic activity have been established with Nalm-6-MSH+ cells and their sensitivity to mutagenicity and cytotoxicity of benzo[a]pyrene diol epoxide (BPDE) and ultraviolet-C light (UV-C) was examined. The low-fidelity mutants were engineered by knocking-in DNA sequences that direct changes of leucine 2618 to either phenylalanine (L2618F) or methionine (L2618M) of Pol ζ. The weak-catalytic-activity mutants were generated by knocking-in DNA sequences that direct changes of either tyrosine 2779 to phenylalanine (Y2779F) or aspartate 2781 to asparagine (D2781N). In addition, a +1 frameshift mutation, i.e., CCC to CCCC, was introduced in the coding region of the TK1 gene to measure the mutant frequencies. Doubling time and spontaneous TK mutant frequencies of the established cell lines were similar to those of the wild-type cells. The low-fidelity mutants displayed, however, higher sensitivity to the mutagenicity of BPDE and UV-C than the wild-type cells although their cytotoxic sensitivity was not changed. In contrast, the weak-catalytic-activity mutants were more sensitive to the cytotoxicity of BPDE and UV-C than the wild-type cells, and displayed much higher sensitivity to the clastogenicity of BPDE than the wild-type cells in an in vitro micronucleus assay. These results indicate that human Pol ζ is involved in TLS across DNA lesions induced by BPDE and UV-C and also that the TLS plays important roles in induction of mutations, clastogenicity and in cellular survival of the damaged human cells. Similarities and differences in in vivo roles of yeast and human Pol ζ in genome integrity are discussed. Copyright © 2016 Elsevier B.V. All rights reserved.

Nondestructive application of laser-induced fluorescence spectroscopy for quantitative analyses of phenolic compounds in strawberry fruits (Fragaria x ananassa).

PubMed

Wulf, J S; Rühmann, S; Rego, I; Puhl, I; Treutter, D; Zude, M

2008-05-14

Laser-induced fluorescence spectroscopy (LIFS) was nondestructively applied on strawberries (EX = 337 nm, EM = 400-820 nm) to test the feasibility of quantitatively determining native phenolic compounds in strawberries. Eighteen phenolic compounds were identified in fruit skin by UV and MS spectroscopy and quantitatively determined by use of rp-HPLC for separation and diode-array or chemical reaction detection. Partial least-squares calibration models were built for single phenolic compounds by means of nondestructively recorded fluorescence spectra in the blue-green wavelength range using different data preprocessing methods. The direct orthogonal signal correction resulted in r (2) = 0.99 and rmsep < 8% for p-coumaroyl-glucose, and r (2) = 0.99 and rmsep < 24% for cinnamoyl-glucose. In comparison, the correction of the fluorescence spectral data with simultaneously recorded reflectance spectra did not further improve the calibration models. Results show the potential of LIFS for a rapid and nondestructive assessment of contents of p-coumaroyl-glucose and cinnamoyl-glucose in strawberry fruits.

The Classification of Ground Roasted Decaffeinated Coffee Using UV-VIS Spectroscopy and SIMCA Method

NASA Astrophysics Data System (ADS)

Yulia, M.; Asnaning, A. R.; Suhandy, D.

2018-05-01

In this work, an investigation on the classification between decaffeinated and non- decaffeinated coffee samples using UV-VIS spectroscopy and SIMCA method was investigated. Total 200 samples of ground roasted coffee were used (100 samples for decaffeinated coffee and 100 samples for non-decaffeinated coffee). After extraction and dilution, the spectra of coffee samples solution were acquired using a UV-VIS spectrometer (Genesys™ 10S UV-VIS, Thermo Scientific, USA) in the range of 190-1100 nm. The multivariate analyses of the spectra were performed using principal component analysis (PCA) and soft independent modeling of class analogy (SIMCA). The SIMCA model showed that the classification between decaffeinated and non-decaffeinated coffee samples was detected with 100% sensitivity and specificity.

[The role of free radicals in the UV-induced skin damage. Photo-aging].

PubMed

Emri, Gabriella; Horkay, Irén; Remenyik, Eva

2006-04-23

The natural (intrinsic) ageing of the skin is enhanced by environmental factors (extrinsic ageing). One of the most important exogenous factors is the solar UV exposure, which results in photo-aging. Besides this, epidemiological and experimental data show a rapid increase in the incidence of human skin cancers, which is also in relation to the increased sunlight exposure of the skin. In the background of these processes there are cell biological effects, photochemical reactions, membrane receptor changes, lipid- and protein modifications, DNA-damage induced by UV. The qualities and quantities of them are wavelength dependent. The UVB photons are absorbed mostly by the DNA of the epidermal keratinocytes, therefore this spectrum is more relevant for photocarcinogenesis. The effect of UVA-irradiation is mainly manifested in the induction of free radicals, which have not only DNA-damaging, but also immunomodulating effect, which also can influence on tumour development. Furthermore, the free radicals cause dermal connective tissue damage as well via activating transcription factors, inducing matrix metalloproteinases, diminishing the procollagen I and fibrillin-1 synthesis. These processes are augmented by mitochondrial DNA mutations, protein oxidation, apoptosis induction. Therefore the enzymes neutralising free radicals and antioxidant molecules, respectively, have an important role in the defence mechanisms. In the therapy of photo-aging the local retinoids lived up to expectations, but the clinical effectiveness of antioxidant vitamins is lower than expected. The most important factor in the prevention of the photo-aging and photocarcinogenesis is the sun protection at present.

Preparation and enhanced daylight-induced photocatalytic activity of C,N,S-tridoped titanium dioxide powders.

PubMed

Zhou, Minghua; Yu, Jiaguo

2008-04-15

A simple method for preparing highly daylight-induced photoactive nanocrystalline C,N,S-tridoped TiO2 powders was developed by a solid-phase reaction. The as-prepared TiO2 powders were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectra, N2 adsorption-desorption measurements and transmission electron microscopy (TEM). The photocatalytic activity was evaluated by the photocatalytic oxidation of formaldehyde under daylight irradiation in air. The results show that daylight-induced photocatalytic activities of the as-prepared TiO2 powders were improved by C,N,S-tridoping. The C,N,S-tridoped TiO2 powders exhibited stronger absorption in the near UV and visible-light region with red shift in the band-gap transition. When the molar ratio of CS(NH2)2 to xerogel TiO2 powders (prepared by hydrolysis of Ti(OC4H9)4 in distilled water) (R) was kept in 3, the daylight-induced photocatalytic activities of the as-prepared C,N,S-tridoped TiO2 powders were about more than six times greater than that of Degussa P25 and un-doped TiO2 powders. The high activities of the C,N,S-tridoped TiO2 can be attributed to the results of the synergetic effects of strong absorption in the near UV and visible-light region, red shift in adsorption edge and two phase structures of un-doped TiO2 and C,N,S-tridoped TiO2.

FTIR Study of the Photoactivation Process of Xenopus (6-4) Photolyase†

PubMed Central

Yamada, Daichi; Zhang, Yu; Iwata, Tatsuya; Hitomi, Kenichi; Getzoff, Elizabeth D.; Kandori, Hideki

2012-01-01

Photolyases (PHRs) are blue-light activated DNA repair enzymes that maintain genetic integrity by reverting UV-induced photoproducts into normal bases. The FAD chromophore of PHRs has four different redox states: oxidized (FADox), anion radical (FAD•−), neutral radical (FADH•) and fully reduced (FADH−). We combined difference Fourier-transform infrared (FTIR) spectroscopy with UV-visible spectroscopy to study the detailed photoactivation process of Xenopus (6-4) PHR. Two photons produce the enzymatically active, fully reduced PHR from oxidized FAD: FADox is converted to semiquinone via light-induced one-electron and one-proton transfers, and then to FADH− by light-induced one-electron transfer. We successfully trapped FAD•− at 200 K, where electron transfer occurs, but proton transfer does not. UV-visible spectroscopy following 450-nm illumination of FADox at 277 K defined the FADH•/FADH− mixture and allowed calculation of difference FTIR spectra among the four redox states. The absence of a characteristic C=O stretching vibration indicated that the proton donor is not a protonated carboxylic acid. Structural changes in Trp and Tyr are suggested from UV-visible and FTIR analysis of FAD•− at 200 K. Spectral analysis of amide-I vibrations revealed structural perturbation of the protein’s β-sheet during initial electron transfer (FAD•− formation), transient increase in α-helicity during proton transfer (FADH• formation) and reversion to the initial amide-I signal following subsequent electron transfer (FADH− formation). Consequently, in (6-4) PHR, unlike cryptochrome-DASH, formation of enzymatically active FADH− did not perturb α-helicity. Protein structural changes in the photoactivation of (6-4) PHR are discussed on the basis of the present FTIR observations. PMID:22747528

Improving UV Resistance of High Performance Fibers

NASA Astrophysics Data System (ADS)

Hassanin, Ahmed

High performance fibers are characterized by their superior properties compared to the traditional textile fibers. High strength fibers have high modules, high strength to weight ratio, high chemical resistance, and usually high temperature resistance. It is used in application where superior properties are needed such as bulletproof vests, ropes and cables, cut resistant products, load tendons for giant scientific balloons, fishing rods, tennis racket strings, parachute cords, adhesives and sealants, protective apparel and tire cords. Unfortunately, Ultraviolet (UV) radiation causes serious degradation to the most of high performance fibers. UV lights, either natural or artificial, cause organic compounds to decompose and degrade, because the energy of the photons of UV light is high enough to break chemical bonds causing chain scission. This work is aiming at achieving maximum protection of high performance fibers using sheathing approaches. The sheaths proposed are of lightweight to maintain the advantage of the high performance fiber that is the high strength to weight ratio. This study involves developing three different types of sheathing. The product of interest that need be protected from UV is braid from PBO. First approach is extruding a sheath from Low Density Polyethylene (LDPE) loaded with different rutile TiO2 % nanoparticles around the braid from the PBO. The results of this approach showed that LDPE sheath loaded with 10% TiO2 by weight achieved the highest protection compare to 0% and 5% TiO2. The protection here is judged by strength loss of PBO. This trend noticed in different weathering environments, where the sheathed samples were exposed to UV-VIS radiations in different weatheromter equipments as well as exposure to high altitude environment using NASA BRDL balloon. The second approach is focusing in developing a protective porous membrane from polyurethane loaded with rutile TiO2 nanoparticles. Membrane from polyurethane loaded with 4% rutile TiO2 nanoparticles showed excellent protection of braid from PBO. Only 7.5% strength loss was observed. To optimize the degree of protection of the sheath loaded with UV blocker particles, computational models were developed to optimize the protective layer thickness/weight and the amount of UV particles that provide the maximum protection with lightest weight of the protective layer and minimum amount of UV particles. The simulated results were found to be higher that the experimental results due to the tendency of nanoparticles to be agglomerated in real experiments. The third approach to achieve a maximum protection with the minimum weight added is constructing a sleeve from SpectraRTM (Ultra High Molecular Weight Polyethylene (UHMWPE) high performance fiber), which is known to resist UV, woven fabric. Covering the braid from PBO fiber with Spectra RTM woven fabric provide hybrid structure with two compatible components that can share the load and thus maintain the high strength to weight ratio. Although the SpectraRTM fabric had maximum cover factor, 20 % of visible light and about 15 % of UV were able to penetrate the fabric. This transmittance of UV-VIS light negatively affected the protection performance of the SpectraRTM woven fabric layer. It is thought that SpectraRTM fabric be coated with a thin layer (mentioned earlier) containing UV blocker for additional protection while maintain strength contribution to the hybrid structure. To maximize the strength to weight ratio of the hybrid structure (with core from PBO braid and sheath from SpectraRTM woven fabric) an established finite element model was utilized. The theoretical results using the finite element theory indicated that by controlling the bending rigidity of the filling yarn of the SpectraRTM fabric, the extension at peak load of woven fabric in warp direction (loading direction) could be controlled to match the braid extension at peak load. The match in the extension at peak load of the two components of the hybrid structure allowed the maximum strength to weight ratio. Thus, the SpectraRTM woven layer could achieve both the protection from UV and the load share in the hybrid structure.

Effect of dehydration in the UV transmittance of "in vitro" corneas

NASA Astrophysics Data System (ADS)

Lincoln, Victor A. C.; Ventura, Liliane; Faria e Sousa, Sidney J.; Mello, Marcio M.

2012-03-01

In ophthalmology the research using "in vitro" corneas are an excellent model for studies of new ophthalmologic procedures, enabling the analysis of effectiveness, performance and even safety parameters of the procedure. In this work we studied four "in vitro" human corneas preserved in OPTISOL-GS, with initial average pachymetry of 542 microns and a post-mortem average of 6 days. The corneas were preserved in OPTISOL-GS and were washed with saline solution to remove the excess the preservative medium. The corneas were placed in a device aligned with an ultraviolet source of 3mw/cm2 and an optical fiber positioned after the device near the endothelium of the cornea. The UV transmittance spectra in the region of 360-370nm were captured by the emission of UV source for 3 seconds. These spectra were captured every 5 minutes in a total of 60 minutes, resulting in 13 spectra per cornea. The measured average initial UV transmittance was 73% and after 50 minutes of dehydration there was no significant difference in the corneal teansmittance properties. However, for the last 10 minutes we have observed a decrease in the UV transmittance of 4%, probably indicated by corneal dehydration and swelling (wrinkling of the cornea tissue. The final average pachymetry was 421 microns and the UV transmittance after the 60 minutes was 69%. Therefore we can suppose that the UV transmittance of corneas "in vitro" is invariant over a period of up to 60 minutes, even with the thickness decrease, since the material that absorbs in the UV region remains intact and only water loss occurs.

UV/blue light-induced fluorescence for assessing apple maturity

NASA Astrophysics Data System (ADS)

Noh, Hyun Kwon; Lu, Renfu

2005-11-01

Chlorophyll fluorescence has been researched for assessing fruit post-harvest quality and condition. The objective of this preliminary research was to investigate the potential of fluorescence spectroscopy for measuring apple fruit quality. Ultraviolet (UV) and blue light was used as an excitation source for inducing fluorescence in apples. Fluorescence spectra were measured from 'Golden Delicious' (GD) and 'Red Delicious' (RD) apples by using a visible/near-infrared spectrometer after one, three, and five minutes of continuous UV/blue light illumination. Standard destructive tests were performed to measure fruit firmness, skin and flesh color, soluble solids and acid content from the apples. Calibration models for each of the three illumination time periods were developed to predict fruit quality indexes. The results showed that fluorescence emission decreased steadily during the first three minutes of UV/blue light illumination and was stable within five minutes. The differences were minimal in the model prediction results based on fluorescence data at one, three or five minutes of illumination. Overall, better predictions were obtained for apple skin chroma and hue and flesh hue with values for the correlation coefficient of validation between 0.80 and 0.90 for both GD and RD. Relatively poor predictions were obtained for fruit firmness, soluble solids content, titrational acid, and flesh chroma. This research demonstrated that fluorescence spectroscopy is potentially useful for assessing selected quality attributes of apple fruit and further research is needed to improve fluorescence measurements so that better predictions of fruit quality can be achieved.

Radiation-induced total-deletion mutations in the human hprt gene: a biophysical model based on random walk interphase chromatin geometry

NASA Technical Reports Server (NTRS)

Wu, H.; Sachs, R. K.; Yang, T. C.

1998-01-01

PURPOSE: To develop a biophysical model that explains the sizes of radiation-induced hprt deletions. METHODS: Key assumptions: (1) Deletions are produced by two DSB that are closer than an interaction distance at the time of DSB induction; (2) Interphase chromatin is modelled by a biphasic random walk distribution; and (3) Misrejoining of DSB from two separate tracks dominates at low-LET and misrejoining of DSB from a single track dominates at high-LET. RESULTS: The size spectra for radiation-induced total deletions of the hprt gene are calculated. Comparing with the results of Yamada and coworkers for gamma-irradiated human fibroblasts the study finds that an interaction distance of 0.75 microm will fit both the absolute frequency and the size spectrum of the total deletions. It is also shown that high-LET radiations produce, relatively, more total deletions of sizes below 0.5 Mb. The model predicts an essential gene to be located between 2 and 3 Mb from the hprt locus towards the centromere. Using the same assumptions and parameters as for evaluating mutation frequencies, a frequency of intra-arm chromosome deletions is calculated that is in agreement with experimental data. CONCLUSIONS: Radiation-induced total-deletion mutations of the human hprt gene and intrachange chromosome aberrations share a common mechanism for their induction.

Zinc finger protein 598 inhibits cell survival by promoting UV-induced apoptosis.

PubMed

Yang, Qiaohong; Gupta, Romi

2018-01-19

UV is one of the major causes of DNA damage induced apoptosis. However, cancer cells adopt alternative mechanisms to evade UV-induced apoptosis. To identify factors that protect cancer cells from UV-induced apoptosis, we performed a genome wide short-hairpin RNA (shRNA) screen, which identified Zinc finger protein 598 (ZNF598) as a key regulator of UV-induced apoptosis. Here, we show that UV irradiation transcriptionally upregulates ZNF598 expression. Additionally, ZNF598 knockdown in cancer cells inhibited UV-induced apoptosis. In our study, we observe that ELK1 mRNA level as well as phosphorylated ELK1 levels was up regulated upon UV irradiation, which was necessary for UV irradiation induced upregulation of ZNF598. Cells expressing ELK1 shRNA were also resistant to UV-induced apoptosis, and phenocopy ZNF598 knockdown. Upon further investigation, we found that ZNF598 knockdown inhibits UV-induced apoptotic gene expression, which matches with decrease in percentage of annexin V positive cell. Similarly, ectopic expression of ZNF598 promoted apoptotic gene expression and also increased annexin V positive cells. Collectively, these results demonstrate that ZNF598 is a UV irradiation regulated gene and its loss results in resistance to UV-induced apoptosis.

Influence of CuO content on the structure of lithium fluoroborate glasses: Spectral and gamma irradiation studies.

PubMed

Abdelghany, A M; ElBatal, H A; EzzElDin, F M

2015-10-05

Glasses of lithium fluoroborate of the composition LiF 15%-B2O3 85% with increasing CuO as added dopant were prepared and characterized by combined optical and FTIR spectroscopy before and after gamma irradiation. The optical spectrum of the undoped glass reveals strong UV absorption with two distinct peaks at about 235 and 310 nm and with no visible bands. This strong UV absorption is related to the presence of unavoidable trace iron impurity (Fe(3+)) within the materials used for the preparation of this glass. After irradiation, the spectrum of the undoped glass shows a decrease of the intensity of the UV bands together with the resolution of an induced visible broad band centered at about 520 nm. The CuO doped glasses reveal the same UV absorption beside a very broad visible band centered at 780 nm and this band shows extension and splitting to several component peaks with higher CuO contents. Upon gamma irradiation, the spectra of all CuO-doped glasses reveal pronounced decrease of their intensities. The response of irradiation on the studied glasses is correlated with suggested photochemical reactions together with some shielding effect of the copper ions. The observed visible band is related to the presence of copper as distorted octahedral Cu(2+) ions. Infrared absorption spectra of the prepared glasses show repetitive characteristic triangular and tetrahedral borate units similar to that published from alkali or alkaline earth oxides B2O3 glasses. A suggested formation of (BO3/2F) tetrahedral units is advanced through action of LiF on B2O3 and these suggested units showing the same position and number as BO4 tetrahedra. Copyright © 2015 Elsevier B.V. All rights reserved.

Optical backbone-sidechain charge transfer transitions in proteins sensitive to secondary structure and modifications.

PubMed

Mandal, I; Paul, S; Venkatramani, R

2018-04-17

The absorption of light by proteins can induce charge transfer (CT) transitions in the UV-visible range of the electromagnetic spectrum. Metal-ligand complexes or active site prosthetic groups which absorb in the visible region exhibit prominent CT transitions. Furthermore, the protein backbone also exhibits CT transitions in the far UV range. In this manuscript, we present a detailed computational study of new near UV-visible CT transitions that involve amino acids with charged side chains. Specifically, using time dependent density functional theory calculations, we examine the absorption spectra of naturally charged amino acids (Lys, Glu, Arg, Asp and His), extracted from solution phase protein structures generated by classical molecular dynamics simulations, and phosphorylated amino acids (Tyr, Thr and Ser) from experimentally determined protein structures. We show that amino acids with charged sidechains present a directed electronic donor-bridge-acceptor paradigm, with the lowest energy optical excitations demonstrating peptide backbone-sidechain charge separations. The UV-visible spectral range of the backbone-sidechain CT transitions is determined by the chemical nature of the donor, bridge and acceptor groups within each amino acid, amino acid conformation and the protein secondary structure where the amino acids are located. Photoinduced CT occurs in opposite directions for the anionic and cationic amino acids along the ground state dipole moment vector for the chromophores. We find that photoinduced charge separation is more facile for the anionic amino acids (Asp, Glu, pSer, pThr and pTyr) relative to that for the cationic amino acids (Lys, Arg and Hsp). Our results provide a foundation for the development of spectroscopic markers based on the recently proposed Protein Charge Transfer Spectra (ProCharTS) which are relevant for the study of DNA-binding or intrinsically disordered proteins that are rich in charged amino acids.

Insight into the interaction of antitubercular and anticancer compound clofazimine with human serum albumin: spectroscopy and molecular modelling.

PubMed

Ajmal, Mohammad Rehan; Zaidi, Nida; Alam, Parvez; Nusrat, Saima; Siddiqi, Mohd Khursheed; Badr, Gamal; Mahmoud, Mohamed H; Khan, Rizwan Hasan

2017-01-01

The binding of clofazimine to human serum albumin (HSA) was investigated by applying optical spectroscopy and molecular docking methods. Fluorescence quenching data revealed that clofazimine binds to protein with binding constant in the order of 10 4  M -1 , and with the increase in temperature, Stern-Volmer quenching constants gradually decreased indicating quenching mode to be static. The UV-visible spectra showed increase in absorbance upon interaction of HSA with clofazimine which further reveals formation of the drug-albumin complex. Thermodynamic parameters obtained from fluorescence data indicate that the process is exothermic and spontaneous. Forster distance (R o ) obtained from fluorescence resonance energy transfer is found to be 2.05 nm. Clofazimine impelled rise in α-helical structure in HSA as observed from far-UV CD spectra while there are minor alterations in tertiary structure of the protein. Clofazimine interacts strongly with HSA inducing secondary structure in the protein and slight alterations in protein topology as suggested by dynamic light scattering results. Moreover, docking results indicate that clofazimine binds to hydrophobic pocket near to the drug site II in HSA.

Wavelengths, f-Values, and Cross Sections in the UV Spectra of Astrophysical Atoms, Ions, and Molecules

NASA Technical Reports Server (NTRS)

Crane, Phil (Technical Monitor); Raymond, John C.; Parkinson, W. H.

2004-01-01

Contents include the following: Improved UV wavelengths, energy levels, and f-values for iron group ions. Update of Kurucz database of wavelengths and f-values. Publication of improved UV photodissociation cross sections for H2O. UV photoabsorption cross sections for CO bands. Service Activities and Data Outreach.

Vesta's UV Lightcurve: Hemispheric Variation in Brightness and Spectral Reversal

NASA Technical Reports Server (NTRS)

Hendrix, Amanda R.; Vilas, Faith; Festou, Michael

2003-01-01

Spectra of asteroid 4 Vesta obtained in October 1990 with the International Ultraviolet Explorer are reanalyzed and reinterpreted. A large portion of the eastern hemisphere (based on the prime meridian definition of Thomas et al., 1997a) is darker at UV Wavelengths than much of the western hemisphere. The UV lightcurve is in contrast with the visible lightcurve, which shows that the eastern hemisphere is brighter than the western. These IUE spectra of Vesta thus may be evidence for the "spectral reversal." first seen on the Moon by Apollo 17. where the visibly brighter lunar highlands are darker than the maria at far-UV wavelengths. This effect was linked to space weathering when it was noted (Wagner et al., 1987) that the spectral reversal appears in the laboratory spectra of lunar soils but not powdered lunar rocks. We investigate Vesta's UV lightcurve and spectral reversal, and its possible connection with space weathering. The addition to grain coatings of small amounts of submicroscopic iron (SMFe) through vapor deposition causes drastic spectral changes at UV-visible wavelengths (Hapke, 2001). while the longer wavelength spectrum remains largely unaffected. Other laboratory results (e.g., Hiroi and Pieters, 1998) indicate that the UV-visible wavelength range is affected by simulated weathering processes in a manner similar to what is seen on Vesta. It is likely that Vesta has experienced relatively minor amounts of space weathering, as indicated by the spectral reversal, along with the subtle visible-near infrared weathering effects (e.g., Binzel et al., 1997).

Overview of xeroderma pigmentosum proteins architecture, mutations and post-translational modifications.

PubMed

Feltes, Bruno César; Bonatto, Diego

2015-01-01

The xeroderma pigmentosum complementation group proteins (XPs), which include XPA through XPG, play a critical role in coordinating and promoting global genome and transcription-coupled nucleotide excision repair (GG-NER and TC-NER, respectively) pathways in eukaryotic cells. GG-NER and TC-NER are both required for the repair of bulky DNA lesions, such as those induced by UV radiation. Mutations in genes that encode XPs lead to the clinical condition xeroderma pigmentosum (XP). Although the roles of XPs in the GG-NER/TC-NER subpathways have been extensively studied, complete knowledge of their three-dimensional structure is only beginning to emerge. Hence, this review aims to summarize the current knowledge of mapped mutations and other structural information on XP proteins that influence their function and protein-protein interactions. We also review the possible post-translational modifications for each protein and the impact of these modifications on XP protein functions. Copyright © 2014 Elsevier B.V. All rights reserved.

Opposing Forces of A/T-Biased Mutations and G/C-Biased Gene Conversions Shape the Genome of the Nematode Pristionchus pacificus

PubMed Central

Weller, Andreas M.; Rödelsperger, Christian; Eberhardt, Gabi; Molnar, Ruxandra I.; Sommer, Ralf J.

2014-01-01

Base substitution mutations are a major source of genetic novelty and mutation accumulation line (MAL) studies revealed a nearly universal AT bias in de novo mutation spectra. While a comparison of de novo mutation spectra with the actual nucleotide composition in the genome suggests the existence of general counterbalancing mechanisms, little is known about the evolutionary and historical details of these opposing forces. Here, we correlate MAL-derived mutation spectra with patterns observed from population resequencing. Variation observed in natural populations has already been subject to evolutionary forces. Distinction between rare and common alleles, the latter of which are close to fixation and of presumably older age, can provide insight into mutational processes and their influence on genome evolution. We provide a genome-wide analysis of de novo mutations in 22 MALs of the nematode Pristionchus pacificus and compare the spectra with natural variants observed in resequencing of 104 natural isolates. MALs show an AT bias of 5.3, one of the highest values observed to date. In contrast, the AT bias in natural variants is much lower. Specifically, rare derived alleles show an AT bias of 2.4, whereas common derived alleles close to fixation show no AT bias at all. These results indicate the existence of a strong opposing force and they suggest that the GC content of the P. pacificus genome is in equilibrium. We discuss GC-biased gene conversion as a potential mechanism acting against AT-biased mutations. This study provides insight into genome evolution by combining MAL studies with natural variation. PMID:24414549

[Preparation of a kind of SERS-active substrates for spot fast analysis].

PubMed

Ji, Nan; Li, Zhi-Shi; Zhao, Bing; Zou, Bo

2013-02-01

A kind of SERS-active substrates was prepared using chemical self-assembly method, aiming at spot fast analysis using portable Raman spectrometer. PDDA was first absorbed on the inner wall of vials, and then Ag colloids were assembled on the inner wall. UV-Vis spectra and Raman spectra of two kinds of blank vials were investigated and the transparent vials were thought to be better for SERS-vials. UV-Vis spectra were used to monitor the assembly process of Ag colloids. SERS activity of our substrates was characterized using p-ATP as probing molecules.

Ultraviolet Spectroscopic Monitoring of a Tidal Disruption Eventd

NASA Astrophysics Data System (ADS)

Kochanek, Chris

2017-08-01

Tidal disruption events (TDE), where supermassive black holes destroy stars toproduce accretion flares, are of great current observational andtheoretical interest. Here we propose a seven epoch STIS UV spectroscopic movie'' of a UV bright TDE spread over the first 90 days after a rapid TOO trigger. The roughly 15 day cadence is comparable to the expected and observed time scales for kinematic changes in theoptical and UV emission and absorption lines. We will measurethe evolution of UV absorption and emission lines from elements(e.g., C, N, Si) and ionization states/potentials not seen in optical spectra of TDEs, which should help to illuminate theirdynamical evolution. In some cases, the debris from the stellar cores should have significantly enhanced [N/C] abundances due to the CNO cycle, so UV spectra can provide a means of differentiating debris fromthe core and the envelope of the disrupted star. Optically-selectedTDEs are energetically dominated by their UV emission, making itthe wavelength range most needed to understand these fascinatingtransients.

MECHANISMS INVOLVED IN TRICHLOROETHYLENE INDUCED LIVER CANCER: IMPORTANCE TO ENVIRONMENTAL CLEANUP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bull, Richard J.; Thrall, Brain D.

2001-12-31

Trichloroethylene (TCE) is a common contaminant of groundwater as a result of poor disposal practices of the past. As a consequence, this solvent is the focus of many clean-up operations of uncontrolled hazardous waste sites. TCE is carcinogenic in both mice and rats, but at different sites, the liver and kidney, respectively (NCI 1976; NTP 1988; NTP 1990). Liver tumor induction in mice has been the tumor most critical from the standpoint of environmental regulation (Bull 2000). Under the proposed cancer risk guidelines of the Environmental Protection Agency (EPA 1996), identifying the dose-response behavior of key events involved in carcinogenicmore » responses can be used for developing alternative risk assessments. A major difficulty in developing alternative approaches for TCE is the fact that three of its metabolites are capable of inducing liver cancer in mice (Bull et al. 1990; Daniel et al. 1992; DeAngelo et al. 1999; Pereria 1996). Two of these metabolites have distinct modes of action, dichloroacetate (DCA) and trichloroacetate (TCA). The third metabolite, chloral hydrate, is probably active as a result of its conversion to one or both of these two metabolites. Ordinarily, the first approach to assigning causality to a metabolite in tumorigenesis would be an attempt to measure its concentration in the body and associate that with tumorigenic concentrations observed when the compound is itself administered. This can be done with relative ease with TCA. However, it has been more difficult with DCA since blood levels of this metabolite after exposure to carcinogenic doses of DCA fall rapidly below detection limits (Kato-Weinstein et al. 1998; Merdink et al. 1998). Mutations in the ras protooncogene have been used to determine if distinct patterns of DNAsequence alterations can provide indications of the type of DNA damage that might be produced by carcinogens. The presence of ras mutations in chemically-induced tumors was suggested as a means o f determining whether a chemical was genotoxic (Wiseman et al. 1986). However, the 7 discovery that spontaneous tumors also contain this oncogene indicated that this assumption may not be correct (Fox and Watanabe 1985). Several non-genotoxic carcinogens have been shown to produce tumors with a H-ras mutation frequency considerably below those that result spontaneously (Maronpot et al. 1995). Among these chemicals are a class called peroxisome proliferators, of which TCA and TCE are members. DCA and TCE were found to induce tumors with similar H-ras mutation spectra (Anna et al. 1994), whereas only limited data have been available on TCA (Fereira-Gonzalez et al. 1995). Thus, a major focus of this research was to evaluate whether the pattern and frequency of H-ras mutations in TCE-induced tumors could be explained by the same parameters in tumors induced by the metabolites TCA or DCA. The present project was organized around three interrelated objectives: The first objective addressed the pharmacokinetic questions regarding the formation and elimination of DCA and TCA in mice administered TCE and whether levels of these metabolites may account for the tumors induced by TCE. The second objective was to investigate potential molecular mechanisms by which TCA and DCA may, in the absence of directly causing mutations, promote the clonal growth and expansion of precancerous cell populations within mouse liver. The third objective was to investigate whether the genotype of tumors induced by TCA and DCA can be used to establish the relative roles of these metabolites in TCE-induced cancer. In particular, the focus of the latter studies was to compare the incidence and spectra of mutations in the H-ras gene (codon 61) to determine if the reported similarities in the genotype of DCA- and TCE-induced tumors have a causal relationship.« less

Changes in surface solar UV irradiances and total ozone during the solar eclipse of August 11, 1999

NASA Astrophysics Data System (ADS)

Zerefos, C. S.; Balis, D. S.; Meleti, C.; Bais, A. F.; Tourpali, K.; Kourtidis, K.; Vanicek, K.; Cappellani, F.; Kaminski, U.; Colombo, T.; Stübi, R.; Manea, L.; Formenti, P.; Andreae, M. O.

2000-11-01

During the solar eclipse of August 11, 1999, intensive measurements of UV solar irradiance and total ozone were performed at a number of observatories located near the path of the Moon's shadow. At the Laboratory of Atmospheric Physics (LAP) of the Aristotle University of Thessaloniki, Greece, global and direct spectra of UV solar irradiances (285-365 nm) were recorded with a double monochromator, and erythemal irradiances were measured with broadband pyranometers. In addition, higher-frequency measurements of global and direct irradiances at six UV wavelengths were performed with a single Brewer spectrophotometer. Total ozone measurements were also performed with Dobson and Brewer spectrophotometers at Hradec Kralove (Czech Republic), Ispra (Italy), Sestola (Italy), Hohenpeissenberg (Germany), Bucharest (Romania), Arosa (Switzerland), and Thessaloniki (Greece). From the spectral UV measurements the limb darkening effect of the solar disk was tentatively quantified from differences of measured solar spectral irradiances at the peak of the eclipse (near to limb conditions) and before the eclipse. Two blackbody curves were fit to the preeclipse and peak eclipse spectra, which have shown a difference in effective temperatures of about 165°K between the limb and the whole of the solar disk. The limb darkening effect is larger at the shorter UV wavelengths. The ratio of the diffuse to direct solar irradiances during the eclipse shows that the diffuse component is reduced much less compared to the decline of the direct solar irradiance at the shorter wavelengths. Moreover, a 20-min oscillation of erythemal UV-B solar irradiance was observed before and after the time of the eclipse maximum under clear skies, indicating a possible 20-min fluctuation in total ozone, presumably caused by the eclipse-induced gravity waves. This work also shows that routine total ozone measurements with a Brewer or a Dobson spectrophotometer should be used with caution during a solar eclipse. This is because the diffuse light increases by more than 30% with respect to the direct solar radiation, increasing more at the shorter wavelength side of the UV spectrum. This plausible mechanism introduces an artificial decrease in total ozone during solar eclipse of more than 30 Dobson units (DU), which is confirmed by all Brewer and Dobson measurements. Changes in total ozone cited earlier in the refereed literature have not been confirmed in the present study.

Theoretical and Experimental Spectroscopic Analysis of Cyano-Substituted Styrylpyridine Compounds

PubMed Central

Castro, Maria Eugenia; Percino, Maria Judith; Chapela, Victor M.; Ceron, Margarita; Soriano-Moro, Guillermo; Lopez-Cruz, Jorge; Melendez, Francisco J.

2013-01-01

A combined theoretical and experimental study on the structure, infrared, UV-Vis and 1H NMR data of trans-2-(m-cyanostyryl)pyridine, trans-2-[3-methyl-(m-cyanostyryl)] pyridine and trans-4-(m-cyanostyryl)pyridine is presented. The synthesis was carried out with an efficient Knoevenagel condensation using green chemistry conditions. Theoretical geometry optimizations and their IR spectra were carried out using the Density Functional Theory (DFT) in both gas and solution phases. For theoretical UV-Vis and 1H NMR spectra, the Time-Dependent DFT (TD-DFT) and the Gauge-Including Atomic Orbital (GIAO) methods were used, respectively. The theoretical characterization matched the experimental measurements, showing a good correlation. The effect of cyano- and methyl-substituents, as well as of the N-atom position in the pyridine ring on the UV-Vis, IR and NMR spectra, was evaluated. The UV-Vis results showed no significant effect due to electron-withdrawing cyano- and electron-donating methyl-substituents. The N-atom position, however, caused a slight change in the maximum absorption wavelengths. The IR normal modes were assigned for the cyano- and methyl-groups. 1H NMR spectra showed the typical doublet signals due to protons in the trans position of a double bond. The theoretical characterization was visibly useful to assign accurately the signals in IR and 1H NMR spectra, as well as to identify the most probable conformation that could be present in the formation of the styrylpyridine-like compounds. PMID:23429190

Severe Early-Onset Combined Immunodeficiency due to Heterozygous Gain-of-Function Mutations in STAT1.

PubMed

Baris, Safa; Alroqi, Fayhan; Kiykim, Ayca; Karakoc-Aydiner, Elif; Ogulur, Ismail; Ozen, Ahmet; Charbonnier, Louis-Marie; Bakır, Mustafa; Boztug, Kaan; Chatila, Talal A; Barlan, Isil B

2016-10-01

Loss and gain-of-function (GOF) mutations in human signal transducer and activator of transcription 1 (STAT1) lead to distinct phenotypes. Although recurrent infections are common to both types of STAT1 mutations, GOF mutations are distinguished by chronic mucocutaneous candidiasis and autoimmunity. However, the clinical spectra of STAT1 GOF mutations continue to expand. We here describe two patients with STAT1 GOF mutations presenting early in life with combined immunodeficiency (CID). Clinical data and laboratory findings including immunophenotyping, level of interferon (IFN)-γ/IL-17(+) T cells, interferon-induced STAT1 phosphorylation, and JAK inhibitor assays were evaluated. Sequencing of STAT1 gene was performed by Sanger sequencer. Patient 1 (P1) had persistent oral candidiasis and cytomegalovirus (CMV) infection since 2 months of age and later developed cavitary lung lesions due to Mycobacterium tuberculosis. Patient 2 (P2) presented with oral candidiasis and recurrent pneumonia at 4 months of age and subsequently developed CMV pneumonitis. Both patients suffered heterozygous missense mutations in STAT1, leading to deleterious amino acid substitutions in the DNA binding domain (P1: c.1154C > T; p.T385M; P2. c.971G > T; p.C324F). Circulating CD4(+) T cells of both patients exhibited increased interferon-γ and decreased IL-17 expression as compared to controls. They also exhibited increased IFN-β and -γ-induced STAT1 phosphorylation that was reversed upon treatment with the JAK kinase inhibitor ruxolitinib. STAT1 GOF mutations may present early in life with CID, consistent with the clinical heterogeneity of the disease. JAK kinase inhibitors may potentially be useful in some patients as adjunct therapy pending definitive treatment with bone marrow transplantation.

The effect of simulated low earth orbit radiation on polyimides (UV degradation study)

NASA Technical Reports Server (NTRS)

Forsythe, John S.; George, Graeme A.; Hill, David J. T.; Odonnell, James H.; Pomery, Peter J.; Rasoul, Firas A.

1995-01-01

UV degradation of polyimide films in air and vacuum were studied using UV-visible, ESR, FTIR, and XPS spectroscopies. The UV-visible spectra of polyimide films showed a blue shift in the absorption compared to Kapton. This behavior was attributed to the presence of bulky groups and kinks along the polymer chains which disrupt the formation of a charge transfer complex. The UV-visible spectra showed also that UV irradiation of polyimides result extensively in surface degradation, leaving the bulk of the polymer intact. ESR spectra of polyimides irradiated in vacuum revealed the formation of stable carbon-centered radicals which give a singlet ESR spectrum, while polyimides irradiated in air produced an asymmetric signal shifted to a lower magnetic field, with a higher g value and line width. This signal was attributed to oxygen-cenetered radicals of peroxy and/or alkoxy type. The rate of radical formation in air was two fold higher than for vacuum irradiation, and reached a plateau after a short time. This suggests a continuous depletion of radicals on the surface via an ablative degradation process. FTIR, XPS, and weight loss studies supported this postulate. An XPS study of the surface indicated a substantial increase in the surface oxidation after irradiation in air. The sharp increase in the C-O binding energy peak relative to the C-C peak was believed to be associated with an aromatic ring opening reaction.

Mutagenicity of furan in female Big Blue B6C3F1 mice

PubMed Central

Terrell, Ashley N.; Huynh, Mailee; Grill, Alex E.; Kovi, Ramesh C.; O’Sullivan, M. Gerard; Guttenplan, Joseph B.; Ho, Yen-Yi; Peterson, Lisa A.

2014-01-01

Furan is an abundant food and environmental contaminant that is a potent liver carcinogen in rodent models. To determine if furan is genotoxic in vivo, female B6C3F1 Big Blue transgenic mice were treated with 15 mg/kg bw furan by gavage 5 days a week for 6 weeks, or once weekly for 3 weeks. Liver cII trans-gene mutation-frequency and mutation spectra were determined. Furan did not increase the mutation frequency under either treatment condition. In the 6-week treatment regimen, there was a change in the cII transgene mutation-spectrum, with the fraction of GC to AT transitions significantly reduced. The only other significant change was an increase in GC to CG transversions; these represented a minor contribution to the overall mutation spectrum. A much larger furan-dependent shift was observed in the 3-week study. There was a significant increase in transversion mutations, predominantly GC to TA transversions as well as smaller non-significant changes in GC to CG and AT to TA transversions. To determine if these mutations were caused by cis-2-butene-1,4-dial (BDA), a reactive metabolite of furan, the mutagenic activity and the mutation spectrum of BDA was determined in vitro, in Big Blue mouse embryonic fibroblasts. This compound did not increase the cII gene mutation-frequency but caused a substantial increase in AT to CG transversions. This increase, however, lost statistical significance when adjusted for multiple comparisons. Together, these findings suggest that BDA may not be directly responsible for the in-vivo effects of furan on mutational spectra. Histopathological analysis of livers from furan-treated mice revealed that furan induced multifocal, hepatocellular necrosis admixed with reactive leukocytes and pigment-laden Kupffer cells, enhanced oval-cell hyperplasia, and increased hepatocyte mitoses, some of which were atypical. An indirect mechanism of genotoxicity is proposed in which chronic toxicity followed by inflammation and secondary cell proliferation triggers cancer development in furan-exposed rodents. PMID:25344163

Advances in Radiation Mutagenesis through Studies on Drosophila

DOE R&D Accomplishments Database

Muller, H. J.

1958-06-01

The approximately linear relation between radiation dose and induced lethals known for Drosophila spermatozoa, is now extended to spermatids. Data are included regarding oogonia. The linearity principle has been confined for minute structural changes in sperm as multi-hit events, on about the 1.5 power of the dose, long known for spermatozoa, is now extended to spermatids and late oocytes, for relatively short exposures. are found to allow union of broken chromosomes. Therefore, the frequencies are lower for more dispersed exposures of varies with lethals induced in late oocytes follow the same frequency pattern and there fore are multi-hit events. Yet han spermatozoan irradiation that two broken ends derived from nonreciprocal. The following is the order of decreasing radiation mutability of different stages found by ourselves and others: spermatids, spermatozoa in females, spermatozoa 0 to 1 day before ejaculation, earlier spermatozoa, late oocytes, gonia of either sex. Lethal frequencies for these stages range over approximately an order of magnitude, gross structural changes far more widely. Of potential usefulness is our extension of genesis by anoxia, known for spermatozoa in adult males, to those in pupal males and in females, to sperion is especially marked but the increase caused by substituting oxygen for air is less marked, perhaps because of enzymatic differences. In contrast, the induction of gross structural changes in oocytes, but not in spermatids, is markedly reduced by oxygen post-treatment; it is increased by dehydration. The efficacy of induction of structural changes by treatment of spermatozoa, whether with radiation or chemical mutagen, is correlated with the conditions of sperm utilization and egg production. Improving our perspective on radiation effects, some 800,000 offspring have been scored for spontaneous visible mutations of 13 specific loci. The average point-mutation rate was 0.5 to 1.0 per locus among 10/sup 5/ germ cells. Most mutation occurred in peri- fertilization stages. All loci studied mutated from one to nine times. Loci mutating oftener spontaneously also gave more radiation mutation, in other studies, Spectra of individual loci prove similar for spontaneous and induced mutation. Studies on back-mutation also showed similarity of spontaneous and radiation mutations. The doubling dose for back-mutations of forked induced in spermatozoa was several hundred roentgens, gonia at diverse loci. Recent analyses of human mutational load lead to mutation-rate estimated like those earlier based on extrapolations from Drosophila, thus supporting the significance for man of the present studies. (auth)

Genome sequencing of mucosal melanomas reveals that they are driven by distinct mechanisms from cutaneous melanoma.

PubMed

Furney, Simon J; Turajlic, Samra; Stamp, Gordon; Nohadani, Mahrokh; Carlisle, Anna; Thomas, J Meirion; Hayes, Andrew; Strauss, Dirk; Gore, Martin; van den Oord, Joost; Larkin, James; Marais, Richard

2013-07-01

Mucosal melanoma displays distinct clinical and epidemiological features compared to cutaneous melanoma. Here we used whole genome and whole exome sequencing to characterize the somatic alterations and mutation spectra in the genomes of ten mucosal melanomas. We observed somatic mutation rates that are considerably lower than occur in sun-exposed cutaneous melanoma, but comparable to the rates seen in cancers not associated with exposure to known mutagens. In particular, the mutation signatures are not indicative of ultraviolet light- or tobacco smoke-induced DNA damage. Genes previously reported as mutated in other cancers were also mutated in mucosal melanoma. Notably, there were substantially more copy number and structural variations in mucosal melanoma than have been reported in cutaneous melanoma. Thus, mucosal and cutaneous melanomas are distinct diseases with discrete genetic features. Our data suggest that different mechanisms underlie the genesis of these diseases and that structural variations play a more important role in mucosal than in cutaneous melanomagenesis. Copyright © 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Color tuning of photonic gel films by UV irradiation

NASA Astrophysics Data System (ADS)

Shin, Sung Eui; Kim, Su Young; Shin, Dong Myung

2010-02-01

Block copolymers have drawn increasing attention for fabricating functional nanomaterials due to their properties of self-assembly. In particular, photonic crystals hold promise for multiple optical applications. We prepared 1D photonic crystals with polystyrene-b-poly(2-vinyl pyridine) (PS-b-P2VP) lamellar films which is hydrophobic block-hydrophilic polyelectrolyte block polymer of 57 kg /mol-b-57 kg/mol. The lamellar stacks, which are alternating layers of hydrophilic and hydrophobic moiety of PS-b-P2VP, are obtained by exposing the spin coated film under chloroform vapor. The band gaps of the lamellar films interestingly varied after immersion into the quaternizing solvents containing 5wt% of iodomethane solubilized in n-hexane. We demonstrate about the influence of UV light on those photonic gel films. To study of different properties of films, UV-visible absorption spectra were measured as a different UV irradiation time at swollen films with distilled water. The UV-visible maximum absorption spectra shifted by UV irradiation time. Dependent on the time of UV irradiations, we can change the photonic band gap.

Oxidative damage in DNA bases revealed by UV resonant Raman spectroscopy.

PubMed

D'Amico, Francesco; Cammisuli, Francesca; Addobbati, Riccardo; Rizzardi, Clara; Gessini, Alessandro; Masciovecchio, Claudio; Rossi, Barbara; Pascolo, Lorella

2015-03-07

We report on the use of the UV Raman technique to monitor the oxidative damage of deoxynucleotide triphosphates (dATP, dGTP, dCTP and dTTP) and DNA (plasmid vector) solutions. Nucleotide and DNA aqueous solutions were exposed to hydrogen peroxide (H2O2) and iron containing carbon nanotubes (CNTs) to produce Fenton's reaction and induce oxidative damage. UV Raman spectroscopy is shown to be maximally efficient to reveal changes in the nitrogenous bases during the oxidative mechanisms occurring on these molecules. The analysis of Raman spectra, supported by numerical computations, revealed that the Fenton's reaction causes an oxidation of the nitrogenous bases in dATP, dGTP and dCTP solutions leading to the production of 2-hydroxyadenine, 8-hydroxyguanine and 5-hydroxycytosine. No thymine change was revealed in the dTTP solution under the same conditions. Compared to single nucleotide solutions, plasmid DNA oxidation has resulted in more radical damage that causes the breaking of the adenine and guanine aromatic rings. Our study demonstrates the advantage of using UV Raman spectroscopy for rapidly monitoring the oxidation changes in DNA aqueous solutions that can be assigned to specific nitrogenous bases.

Sequential folding of UmuC by the Hsp70 and Hsp60 chaperone complexes of Escherichia coli.

PubMed

Petit, M A; Bedale, W; Osipiuk, J; Lu, C; Rajagopalan, M; McInerney, P; Goodman, M F; Echols, H

1994-09-23

Replication-blocking lesions generate a signal in Escherichia coli that leads to the induction of the multigene SOS response. Among the SOS-induced genes are umuD and umuC, whose products are necessary for the increased mutation rate in induced bacteria. The mutations are likely to result from replication across the DNA lesion, and such a bypass event has been reconstituted in vitro (Rajagopalan, M., L, C., Woodgate, R., O'Donnel, M., Goodman, M. F., Echols, H. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 10777-10781). In this work, we show that the chaperone proteins promote the proper folding of UmuC protein in vitro. We treated purified and inactive UmuC with Hsp70 and Hsp60. After Hsp70 treatment, the DNA binding activity of UmuC was recovered, but the ability to promote replication across DNA lesions was not. However, lesion bypass activity was recovered upon further treatment with Hsp60. The biological significance of such a folding pathway for UmuC protein is strengthened by in vivo evidence for a role of DnaK in UV-induced mutagenesis.

Photon-induced formation of CdS nanocrystals in selected areas of polymer matrices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Athanassiou, Athanassia; Cingolani, Roberto; Tsiranidou, Elsa

2007-10-08

We demonstrate light-induced formation of semiconductor quantum dots in TOPAS registered polymer matrix with very high control of their size and their spatial localization. Irradiation with UV laser pulses of polymer films embedding Cd thiolate precursors results in the formation of cadmium sulfide nanocrystals well confined in the irradiation area, through a macroscopically nondestructive procedure for the host matrix. With increasing number of laser pulses, we accomplish the formation of nanoparticles with gradually increasing dimensions, resulting in the dynamic change of the spectra emitted by the formed nanocomposite areas. The findings are supported by x-ray diffraction and transmission electron microscopymore » measurements.« less

Induced Star Formation

NASA Astrophysics Data System (ADS)

Kennicutt, Robert C., Jr.

Overview: Induced Star Formation and Interactions Introduction Historical Background: First Hints Systematic Studies: Starbursts Interactions and Nuclear activity IRAS and Ultralumious starburst Galaxies The 1990's: HST, Supercomputers, and the Distant Universe Key Questions and Issues Organization of Lectures Star Formation Properties of Normal Galaxies Observational Techniques Results: Star Formation in Normal Galaxies Interpretation: Star Formation Histories Global Star Formation in interacting Galaxies A Gallery of Interactions and Mergers Star Formation Statistics: Guilt By Association Tests SFRs in Interacting vs Noninteracting Galaxies Kinematic Properties and Regulation of SFRs Induced Nuclear Activity and Star Formation Background: Nuclear Spectra and Classification Nuclear Star Formation and Starbursts Nuclear Star Formation and Interactions Induced AGN Activity: Statistics of Seyfert Galaxies Environments of Quasars Kinematic Clues to the Triggering of AGNs Infrared Luminous Galaxies and Starbursts Background: IR Luminous Galaxies and IRAS Infrared Luminosity Function and Spectra Infrared Structure and Morphology Interstellar Gas X-Ray Emission and Superwinds Optical, UV, and Near-Infrared Spectra Radio Continuum Emission Evidence for Interactions and Mergers The Power Source: Starbursts or Dusty AGNs? Spectral Diagnostics of Starbursts Evolutionary Synthesis Models Applications: Integrated Colors of Interacting Galaxies Applications: Hα Emission, Colors, and SFRs Applications: Spectral Modelling of Evolved Starbursts Infrared Starbursts and the IMF in starbursts Triggering and Regulation of Star Formation: The Problem Introduction: Star Formation as a Nonlinear Process The schmidt Law in Normal Galaxies Star Formation Regimes in Interacting Galaxies Summary Triggering and Regulation of Starbusts: Theoretical Ideas Gravitational Star Formation Thresholds Cloud Collision Models Radial Transport of Gas: Clues from Barred Galaxies Simulations of Starbursts in Merging Galaxies The Cosmological Role of Interactions and Starbursts Interactions in Hierarchical Cosmology Interaction-Induced Star Formation Today Interaction-Induced Star Formation in the Past Disk kinematics and the Merger Rate Global Effects of Starbursts and Superwinds Concluding Remarks References

Lysozyme Photochemistry as a Function of Temperature. The Protective Effect of Nanoparticles on Lysozyme Photostability

PubMed Central

Oliveira Silva, Catarina; Petersen, Steffen B.; Pinto Reis, Catarina; Rijo, Patrícia; Molpeceres, Jesús; Vorum, Henrik; Neves-Petersen, Maria Teresa

2015-01-01

The presence of aromatic residues and their close spatial proximity to disulphide bridges makes hen egg white lysozyme labile to UV excitation. UVB induced photo-oxidation of tryptophan and tyrosine residues leads to photochemical products, such as, kynurenine, N–formylkynurenine and dityrosine and to the disruption of disulphide bridges in proteins. We here report that lysozyme UV induced photochemistry is modulated by temperature, excitation power, illumination time, excitation wavelength and by the presence of plasmonic quencher surfaces, such as gold, and by the presence of natural fluorescence quenchers, such as hyaluronic acid and oleic acid. We show evidence that the photo-oxidation effects triggered by 295 nm at 20°C are reversible and non-reversible at 10°C, 25°C and 30°C. This paper provides evidence that the 295 nm damage threshold of lysozyme lies between 0.1 μW and 0.3 μW. Protein conformational changes induced by temperature and UV light have been detected upon monitoring changes in the fluorescence emission spectra of lysozyme tryptophan residues and SYPRO® Orange. Lysozyme has been conjugated onto gold nanoparticles, coated with hyaluronic acid and oleic acid (HAOA). Steady state and time resolved fluorescence studies of free and conjugated lysozyme onto HAOA gold nanoparticles reveals that the presence of the polymer decreased the rate of the observed photochemical reactions and induced a preference for short fluorescence decay lifetimes. Size and surface charge of the HAOA gold nanoparticles have been determined by dynamic light scattering and zeta potential measurements. TEM analysis of the particles confirms the presence of a gold core surrounded by a HAOA matrix. We conclude that HAOA gold nanoparticles may efficiently protect lysozyme from the photochemical effects of UVB light and this nanocarrier could be potentially applied to other proteins with clinical relevance. In addition, this study confirms that the temperature plays a critical role in the photochemical pathways a protein enters upon UV excitation. PMID:26656259

Lysozyme Photochemistry as a Function of Temperature. The Protective Effect of Nanoparticles on Lysozyme Photostability.

PubMed

Oliveira Silva, Catarina; Petersen, Steffen B; Pinto Reis, Catarina; Rijo, Patrícia; Molpeceres, Jesús; Vorum, Henrik; Neves-Petersen, Maria Teresa

2015-01-01

The presence of aromatic residues and their close spatial proximity to disulphide bridges makes hen egg white lysozyme labile to UV excitation. UVB induced photo-oxidation of tryptophan and tyrosine residues leads to photochemical products, such as, kynurenine, N-formylkynurenine and dityrosine and to the disruption of disulphide bridges in proteins. We here report that lysozyme UV induced photochemistry is modulated by temperature, excitation power, illumination time, excitation wavelength and by the presence of plasmonic quencher surfaces, such as gold, and by the presence of natural fluorescence quenchers, such as hyaluronic acid and oleic acid. We show evidence that the photo-oxidation effects triggered by 295 nm at 20°C are reversible and non-reversible at 10°C, 25°C and 30°C. This paper provides evidence that the 295 nm damage threshold of lysozyme lies between 0.1 μW and 0.3 μW. Protein conformational changes induced by temperature and UV light have been detected upon monitoring changes in the fluorescence emission spectra of lysozyme tryptophan residues and SYPRO® Orange. Lysozyme has been conjugated onto gold nanoparticles, coated with hyaluronic acid and oleic acid (HAOA). Steady state and time resolved fluorescence studies of free and conjugated lysozyme onto HAOA gold nanoparticles reveals that the presence of the polymer decreased the rate of the observed photochemical reactions and induced a preference for short fluorescence decay lifetimes. Size and surface charge of the HAOA gold nanoparticles have been determined by dynamic light scattering and zeta potential measurements. TEM analysis of the particles confirms the presence of a gold core surrounded by a HAOA matrix. We conclude that HAOA gold nanoparticles may efficiently protect lysozyme from the photochemical effects of UVB light and this nanocarrier could be potentially applied to other proteins with clinical relevance. In addition, this study confirms that the temperature plays a critical role in the photochemical pathways a protein enters upon UV excitation.

Effect of surface plasmon resonance on the photocatalytic activity of Au/TiO2 under UV/visible illumination.

PubMed

Tseng, Yao-Hsuan; Chang, I-Guo; Tai, Yian; Wu, Kung-Wei

2012-01-01

In this study, gold-loaded titanium dioxide was prepared by an impregnation method to investigate the effect of surface plasmon resonance (SPR) on photoactivity. The deposited gold nanoparticles (NPs) absorb visible light because of SPR. The effects of both the gold content and the TiO2 size of Au/TiO2 on SPR and the photocatalytic efficiency were investigated. The morphology, crystal structure, light absorption, emission from the recombination of a photoexcited electron and hole, and the degree of aggregation were investigated using transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-visible-diffuse reflectance spectra (UV-VIS-DRS), photoluminescence (PL) spectroscopy, and turbidimetry, respectively. Photocatalytic activity was evaluated by the decolorization of methyl orange solution over modified titania under UV and UV/GLED (green light emitting diode) illumination. Au/TiO2 NPs exhibited an absorption peak (530-570 nm) because of SPR. The results of our photocatalytic experiments indicated that the UV-inducedly photocatalytic reaction rate was improved by simultaneously using UV and green light illumination; this corresponds to the adsorption region of SPR. Au/TiO2 could use the enhanced electric field amplitude on the surface of the Au particle in the spectral vicinity of its plasmon resonance and thus improve the photoactivity. Experimental results show that the synergistic effect between UV and green light for the improvement of photoactivity increases with increasing the SPR absorption, which in turn is affected by the Au content and TiO2 size.

Ultraviolet electroluminescence from hybrid inorganic/organic ZnO/GaN/poly(3-hexylthiophene) dual heterojunctions.

PubMed

Chen, Yungting; Shih, Hanyu; Wang, Chunhsiung; Hsieh, Chunyi; Chen, Chihwei; Chen, Yangfang; Lin, Taiyuan

2011-05-09

Based on hybrid inorganic/organic n-ZnO nanorods/p-GaN thin film/poly(3-hexylthiophene)(P3HT) dual heterojunctions, the light emitting diode (LED) emits ultraviolet (UV) radiation (370 nm - 400 nm) and the whole visible light (400 nm -700 nm) at the low injection current density. Meanwhile, under the high injection current density, the UV radiation overwhelmingly dominates the room-temperature electroluminescence spectra, exponentially increases with the injection current density and possesses a narrow full width at half maximum less than 16 nm. Comparing electroluminescence with photoluminescence spectra, an enormously enhanced transition probability of the UV luminescence in the electroluminescence spectra was found. The P3HT layer plays an essential role in helping the UV emission from p-GaN material because of its hole-conductive characteristic as well as the band alignment with respect to p-GaN. With our new finding, the result shown here may pave a new route for the development of high brightness LEDs derived from hybrid inorganic/organic heterojuctions.

Tomographic separation of composite spectra. The components of Plaskett's Star

NASA Technical Reports Server (NTRS)

Bagnuolo, William G., Jr.; Gies, Douglas R.; Wiggs, Michael S.

1991-01-01

The UV photospheric lines of Plaskett's Star (HD 47129), a 14.4 day period, double lined O-type spectroscopic binary were analyzed. Archival data from IUE (17 spectra well distributed in orbital phase) were analyzed with several techniques. A cross correlation analysis, which showed that the secondary produces significant lines in the UV, indicates that the mass ratio is q = 1.18 + or - 0.12 (secondary slightly more massive). A tomography algorithm was used to produce the separate spectra of the two stars in six spectral regions. The interpolated spectral classifications of the primary and secondary, 07.3 I and 06.2 I, respectively, were estimated through a comparison of UV line ratios with those in spectral standard stars. The intensity ratio of the stars in the UV is 0.53 + or - 0.05 (primary brighter). The secondary lines appear rotationally broadened, and the projected rotational velocity V sin i for this star is estimated to be 310 + or - 20 km/s. The possible evolutionary history of this system is discussed through a comparison of the positions of the components and evolutionary tracks in the H-R diagram.

Examples for the importance of radiophysical measurements in clinical phototherapy.

PubMed

Schneider, Lars Alexander; Wlaschek, Meinhard; Dissemond, Joachim; Scharffetter-Kochanek, Karin

2007-05-01

Optimal UV therapy requires regular surveillance of the variables that influence therapeutic success. In daily practice, phototherapy equipment is often operated with an attitude of "autocontrol." This implies that thorough control measurements of the emission spectra and calibration of UV fluences are not routinely performed. For both quality control and patient safety, it is essential to regularly check whether a UV source is providing the right target spectrum with the correct dose to the skin. We have exemplarily taken three UV sources currently used in clinical practice and performed radiophysical measurements, i. e. determined emission spectra, radiation output and correctness of dose calculation. All three sources revealed either a largely inhomogeneous distribution pattern of radiation intensity, variation of radiation intensity over time or insufficient filtering of the UV lamp emission spectrum. Furthermore the dose calculation procedures had to be revised because of significant differences between the estimated and the administered UV doses. Radiophysical measurement of all UV-equipment in clinical use is a simple and effective way to improve the safety and reliability of phototherapy. Such measurements help to uncover technical flaws in radiation sources and prevent unnecessary side effects and UV exposure risks for the patient.

Stars and gas in the most metal-deficient galaxies in the Universe.

NASA Astrophysics Data System (ADS)

Wofford, Aida

2017-08-01

Improving our understanding of star formation at low metallicity is of large relevance for a variety of fields in astrophysics since it relates to multiple topical questions. These range from understanding the properties of galaxies that contributed to cosmic reionization to the evolution of metal poor massive stars that give rise to the formation of heavy binary black holes. Crucial are observational constraints for the theoretical predictions, which can be obtained from rest-frame UV spectra of local star-forming dwarf galaxies with ionized-gas oxygen abundances at the low-metallicity threshold of the nearby Universe.While samples of UV spectra exist for galaxies in the metallicity range above 1/20 solar, only two useful spectra covering from H I Lyman-alpha (LyA, 1216 Ang) to C III] 1909 are available at lower metallicites. We propose COS G140L observations of eight extremely-metal poor galaxies (XMPGs) with He II emission that will: i) provide three more spectra with 12+log(O/H)=<7.4 (suitable targets at such low Z are hard to find), and ii) leverage existing WFC3 and Chandra images which are useful for discrimintating among different sources of ionization. Combining this dataset with existing spectra at similar and higher metallicity will allow us to address three questions: 1) How does metallicity determine galaxy properties?, 2) Is narrow He II emission a good tracer of peculiar massive stars?, and 3) Can we probe star-formation at high redshift with UV lines other than LyA? Our study will provide valuable clues for interpreting rest-frame UV spectra of high-z galaxies that will challenge our understanding of star formation at low Z.

ATP interacts with the CPVT mutation-associated central domain of the cardiac ryanodine receptor.

PubMed

Blayney, Lynda; Beck, Konrad; MacDonald, Ewan; D'Cruz, Leon; Nomikos, Michail; Griffiths, Julia; Thanassoulas, Angelos; Nounesis, George; Lai, F Anthony

2013-10-01

This study was designed to determine whether the cardiac ryanodine receptor (RyR2) central domain, a region associated with catecholamine polymorphic ventricular tachycardia (CPVT) mutations, interacts with the RyR2 regulators, ATP and the FK506-binding protein 12.6 (FKBP12.6). Wild-type (WT) RyR2 central domain constructs (G(2236)to G(2491)) and those containing the CPVT mutations P2328S and N2386I, were expressed as recombinant proteins. Folding and stability of the proteins were examined by circular dichroism (CD) spectroscopy and guanidine hydrochloride chemical denaturation. The far-UV CD spectra showed a soluble stably-folded protein with WT and mutant proteins exhibiting a similar secondary structure. Chemical denaturation analysis also confirmed a stable protein for both WT and mutant constructs with similar two-state unfolding. ATP and caffeine binding was measured by fluorescence spectroscopy. Both ATP and caffeine bound with an EC50 of ~200-400μM, and the affinity was the same for WT and mutant constructs. Sequence alignment with other ATP binding proteins indicated the RyR2 central domain contains the signature of an ATP binding pocket. Interaction of the central domain with FKBP12.6 was tested by glutaraldehyde cross-linking and no association was found. The RyR2 central domain, expressed as a 'correctly' folded recombinant protein, bound ATP in accord with bioinformatics evidence of conserved ATP binding sequence motifs. An interaction with FKBP12.6 was not evident. CPVT mutations did not disrupt the secondary structure nor binding to ATP. Part of the RyR2 central domain CPVT mutation cluster, can be expressed independently with retention of ATP binding. Copyright © 2013 Elsevier B.V. All rights reserved.

Computational DNA hole spectroscopy: A new tool to predict mutation hotspots, critical base pairs, and disease ‘driver’ mutations

PubMed Central

Suárez, Martha Y.; Villagrán; Miller, John H.

2015-01-01

We report on a new technique, computational DNA hole spectroscopy, which creates spectra of electron hole probabilities vs. nucleotide position. A hole is a site of positive charge created when an electron is removed. Peaks in the hole spectrum depict sites where holes tend to localize and potentially trigger a base pair mismatch during replication. Our studies of mitochondrial DNA reveal a correlation between L-strand hole spectrum peaks and spikes in the human mutation spectrum. Importantly, we also find that hole peak positions that do not coincide with large variant frequencies often coincide with disease-implicated mutations and/or (for coding DNA) encoded conserved amino acids. This enables combining hole spectra with variant data to identify critical base pairs and potential disease ‘driver’ mutations. Such integration of DNA hole and variance spectra could ultimately prove invaluable for pinpointing critical regions of the vast non-protein-coding genome. An observed asymmetry in correlations, between the spectrum of human mtDNA variations and the L- and H-strand hole spectra, is attributed to asymmetric DNA replication processes that occur for the leading and lagging strands. PMID:26310834

Computational DNA hole spectroscopy: A new tool to predict mutation hotspots, critical base pairs, and disease 'driver' mutations.

PubMed

Villagrán, Martha Y Suárez; Miller, John H

2015-08-27

We report on a new technique, computational DNA hole spectroscopy, which creates spectra of electron hole probabilities vs. nucleotide position. A hole is a site of positive charge created when an electron is removed. Peaks in the hole spectrum depict sites where holes tend to localize and potentially trigger a base pair mismatch during replication. Our studies of mitochondrial DNA reveal a correlation between L-strand hole spectrum peaks and spikes in the human mutation spectrum. Importantly, we also find that hole peak positions that do not coincide with large variant frequencies often coincide with disease-implicated mutations and/or (for coding DNA) encoded conserved amino acids. This enables combining hole spectra with variant data to identify critical base pairs and potential disease 'driver' mutations. Such integration of DNA hole and variance spectra could ultimately prove invaluable for pinpointing critical regions of the vast non-protein-coding genome. An observed asymmetry in correlations, between the spectrum of human mtDNA variations and the L- and H-strand hole spectra, is attributed to asymmetric DNA replication processes that occur for the leading and lagging strands.

Comprehensive sequence analysis of nine Usher syndrome genes in the UK National Collaborative Usher Study.

PubMed

Le Quesne Stabej, Polona; Saihan, Zubin; Rangesh, Nell; Steele-Stallard, Heather B; Ambrose, John; Coffey, Alison; Emmerson, Jenny; Haralambous, Elene; Hughes, Yasmin; Steel, Karen P; Luxon, Linda M; Webster, Andrew R; Bitner-Glindzicz, Maria

2012-01-01

Usher syndrome (USH) is an autosomal recessive disorder comprising retinitis pigmentosa, hearing loss and, in some cases, vestibular dysfunction. It is clinically and genetically heterogeneous with three distinctive clinical types (I-III) and nine Usher genes identified. This study is a comprehensive clinical and genetic analysis of 172 Usher patients and evaluates the contribution of digenic inheritance. The genes MYO7A, USH1C, CDH23, PCDH15, USH1G, USH2A, GPR98, WHRN, CLRN1 and the candidate gene SLC4A7 were sequenced in 172 UK Usher patients, regardless of clinical type. No subject had definite mutations (nonsense, frameshift or consensus splice site mutations) in two different USH genes. Novel missense variants were classified UV1-4 (unclassified variant): UV4 is 'probably pathogenic', based on control frequency <0.23%, identification in trans to a pathogenic/probably pathogenic mutation and segregation with USH in only one family; and UV3 ('likely pathogenic') as above, but no information on phase. Overall 79% of identified pathogenic/UV4/UV3 variants were truncating and 21% were missense changes. MYO7A accounted for 53.2%, and USH1C for 14.9% of USH1 families (USH1C:c.496+1G>A being the most common USH1 mutation in the cohort). USH2A was responsible for 79.3% of USH2 families and GPR98 for only 6.6%. No mutations were found in USH1G, WHRN or SLC4A7. One or two pathogenic/likely pathogenic variants were identified in 86% of cases. No convincing cases of digenic inheritance were found. It is concluded that digenic inheritance does not make a significant contribution to Usher syndrome; the observation of multiple variants in different genes is likely to reflect polymorphic variation, rather than digenic effects.

Comprehensive sequence analysis of nine Usher syndrome genes in the UK National Collaborative Usher Study

PubMed Central

Le Quesne Stabej, Polona; Saihan, Zubin; Rangesh, Nell; Steele-Stallard, Heather B; Ambrose, John; Coffey, Alison; Emmerson, Jenny; Haralambous, Elene; Hughes, Yasmin; Steel, Karen P; Luxon, Linda M; Webster, Andrew R

2011-01-01

Background Usher syndrome (USH) is an autosomal recessive disorder comprising retinitis pigmentosa, hearing loss and, in some cases, vestibular dysfunction. It is clinically and genetically heterogeneous with three distinctive clinical types (I–III) and nine Usher genes identified. This study is a comprehensive clinical and genetic analysis of 172 Usher patients and evaluates the contribution of digenic inheritance. Methods The genes MYO7A, USH1C, CDH23, PCDH15, USH1G, USH2A, GPR98, WHRN, CLRN1 and the candidate gene SLC4A7 were sequenced in 172 UK Usher patients, regardless of clinical type. Results No subject had definite mutations (nonsense, frameshift or consensus splice site mutations) in two different USH genes. Novel missense variants were classified UV1-4 (unclassified variant): UV4 is ‘probably pathogenic’, based on control frequency <0.23%, identification in trans to a pathogenic/probably pathogenic mutation and segregation with USH in only one family; and UV3 (‘likely pathogenic’) as above, but no information on phase. Overall 79% of identified pathogenic/UV4/UV3 variants were truncating and 21% were missense changes. MYO7A accounted for 53.2%, and USH1C for 14.9% of USH1 families (USH1C:c.496+1G>A being the most common USH1 mutation in the cohort). USH2A was responsible for 79.3% of USH2 families and GPR98 for only 6.6%. No mutations were found in USH1G, WHRN or SLC4A7. Conclusions One or two pathogenic/likely pathogenic variants were identified in 86% of cases. No convincing cases of digenic inheritance were found. It is concluded that digenic inheritance does not make a significant contribution to Usher syndrome; the observation of multiple variants in different genes is likely to reflect polymorphic variation, rather than digenic effects. PMID:22135276

Skylab-3 Mission Onboard Photograph - Astronaut Bean working on Experiment S019

NASA Technical Reports Server (NTRS)

1973-01-01

This Skylab-3 mission onboard photograph shows Astronaut Alan Bean operating the Ultraviolet (UV) Stellar Astronomy experiment (S019) in the Skylab Airlock Module. The S019, a camera with a prism for UV star photography, studied the UV spectra of early-type stars and galaxies.

Spectral identification of abiotic O2 buildup from early runaways and rarefied atmospheres

NASA Astrophysics Data System (ADS)

Schwieterman, Edward; Meadows, Victoria; Domagal-Goldman, Shawn; Arney, Giada; Robinson, Tyler D.; Luger, Rodrigo; Barnes, Rory

2016-01-01

The spectral detection of oxygen (O2) in a planetary atmosphere has been considered a robust signature of life because O2 is highly reactive on planets with Earth-like redox buffers and because significant continuous abiotic sources were thought to be implausible. However, recent work has revealed the possibility that significant O2 may build-up in terrestrial atmospheres through (1) photochemical channels or (2) through the escape of hydrogen. We focus on the latter category here. Significant amounts of abiotic O2 could remain in the atmospheres of planets in the habitable zones of late type stars, where an early runaway greenhouse and massive hydrogen escape during the pre-main-sequence phase could have irreversibly oxidized the crust and mantle (Luger & Barnes 2015). Additionally, it has been hypothesized that O2 could accumulate in the atmospheres of planets with sufficiently low abundances of non-condensable gases such as N2 where water would not be cold trapped in the troposphere, leading to H-escape from UV photolysis in a wet stratosphere (Wordsworth & Pierrehumbert 2014). We self-consistently model the climate, photochemistry, and spectra of both rarefied and post-runaway, high-O2 atmospheres. Because an early runaway might not have lasted long enough for the entire water inventory to escape, we explore both completely desiccated scenarios and cases where a surface ocean remains. We find "habitable" surface conditions for a wide variety of oxygen abundances, atmospheric masses, and CO2 mixing ratios. If O2 builds up from massive or sustained H escape, the O2 abundance should be very high, and could be spectrally indicated by the presence of O2-O2 (O4) collisionally-induced absorption (CIA) features. We generate synthetic direct-imaging and transit transmission spectra of these atmospheres and calculate the strength of the UV/Visible and NIR O4 features. We find that while both the UV/Visible and NIR O4 features are strong in the radiance spectra of very high-O2 atmospheres, only the NIR O4 features are strong in transmission spectra. We also conclude that detection of N2-N2 CIA near 4.2 μm in transmission or direct-imaging spectra could rule out O2 origination from H-escape from thin atmospheres.

The versatile DNA nucleotide excision repair (NER) and its medical significance.

PubMed

Falik-Zaccai, Tzipora C; Keren, Zohar; Slor, Hanoch

2009-12-01

Two of DNA's worst enemies, ultraviolet light and chemical carcinogens, can cause damage to the molecule by mutating individual nucleotides or changing its physical structure. In most cases, genomic integrity is restored by specialized suites of proteins dedicated to repairing specific types of injuries. One restoration mechanism, called nucleotide excision repair (NER), recruits and coordinates the services of 20-30 proteins to recognize and remove structure-impairing lesions, including those induced by ultraviolet (UV) light. Mutations in a gene that encodes a protein from the NER machinery might cause a wide variety of rare inherited human disorders. Sun sensitivity, cancer, developmental retardation, neurodegeneration and premature aging characterize these syndromes. Identification of the causative genes and proteins in affected families in Israel allowed us to establish accurate molecular diagnosis of couples at risk, and provide them with better genetic counseling.

Quantitative classification of cryptosporidium oocysts and giardia cysts in water using UV/vis spectroscopy

NASA Astrophysics Data System (ADS)

Bacon, Christina P.; Rose, J. B.; Patten, K.; Garcia-Rubio, Luis H.

1995-05-01

Cryptosporidium and Giardia are enteric protozoa which cause waterborne diseases. To date, the detection of these organisms in water has relied upon microscopic immunofluorescent assay technology which uses antibodies directed against the cyst and oocyst forms of the protozoa. In this paper, the uv/vis extinction spectra of aqueous dispersions of Cryptosporidium and Giardia have been studied to investigate the potential use of light scattering-spectral deconvolution techniques as a rapid method for the identification and quantification of protozoa in water. Examination of purified samples of Cryptosporidium and Giardia suggests that spectral features apparent in the short wavelength region of the uv/vis spectra contain information that may be species specific for each protozoa. The spectral characteristics, as well as the particle size analysis, determined from the same spectra, allow for the quantitative classification, identification, and possibly, the assessment of the viability of the protozoa. To further increase the sensitivity of this technique, specific antibodies direction against these organisms, labelled with FITC and rhodamine are being used. It is demonstrated that uv/vis spectroscopy provides an alternative method for the characterization of Giardia and Cryptosporidium. The simplicity and reproducibility of uv/vis spectroscopy measurements makes this technique ideally suited for the development of on-line instrumentation for the rapid detection of microorganisms in water supplies.

UV filters for lighting of plants

NASA Astrophysics Data System (ADS)

Doehring, T.; Koefferlein, M.; Thiel, S.; Seidlitz, H. K.; Payer, H. D.

1994-03-01

The wavelength dependent interaction of biological systems with radiation is commonly described by appropriate action spectra. Particularly effective plant responses are obtained for ultraviolet (UV) radiation. Excess shortwave UV-B radiation will induce genetic defects and plant damage. Besides the ecological discussion of the deleterious effects of the excess UV radiation there is increasing interest in horticultural applications of this spectral region. Several metabolic pathways leading to valuable secondary plant products like colors, odors, taste, or resulting in mechanical strength and vitality are triggered by UV radiation. Thus, in ecologically as well as in economically oriented experiments the exact generation and knowledge of the spectral irradiance, particularly near the UV absorption edge, is essential. The ideal filter 'material' to control the UV absorption edge would be ozone itself. However, due to problems in controlling the toxic and chemically aggressive, instable gas, only rather 'small ozone filters' have been realized so far. In artificial plant lighting conventional solid filter materials such as glass sheets and plastic foils (celluloseacetate or cellulosetriacetate) which can be easily handled have been used to absorb the UV-C and the excess shortwave UV-B radiation of the lamp emissions. Different filter glasses are available which provide absorption properties suitable for gradual changes of the spectral UV-B illumination of artificial lighting. Using a distinct set of lamps and filter glasses an acceptable simulation of the UV-B part of natural global radiation can be achieved. The aging of these and other filter materials under the extreme UV radiation in the lamphouse of a solar simulator is presently unavoidable. This instability can be dealt with only by a precise spectral monitoring and by replacing the filters accordingly. For this reason attempts would be useful to develop real ozone filters which can replace glass filters. In any case chamber experiments require a careful selection of the filter material used and must be accompanied by a continuous UV-B monitoring.

UV filters for lighting of plants

NASA Technical Reports Server (NTRS)

Doehring, T.; Koefferlein, M.; Thiel, S.; Seidlitz, H. K.; Payer, H. D.

1994-01-01

The wavelength dependent interaction of biological systems with radiation is commonly described by appropriate action spectra. Particularly effective plant responses are obtained for ultraviolet (UV) radiation. Excess shortwave UV-B radiation will induce genetic defects and plant damage. Besides the ecological discussion of the deleterious effects of the excess UV radiation there is increasing interest in horticultural applications of this spectral region. Several metabolic pathways leading to valuable secondary plant products like colors, odors, taste, or resulting in mechanical strength and vitality are triggered by UV radiation. Thus, in ecologically as well as in economically oriented experiments the exact generation and knowledge of the spectral irradiance, particularly near the UV absorption edge, is essential. The ideal filter 'material' to control the UV absorption edge would be ozone itself. However, due to problems in controlling the toxic and chemically aggressive, instable gas, only rather 'small ozone filters' have been realized so far. In artificial plant lighting conventional solid filter materials such as glass sheets and plastic foils (celluloseacetate or cellulosetriacetate) which can be easily handled have been used to absorb the UV-C and the excess shortwave UV-B radiation of the lamp emissions. Different filter glasses are available which provide absorption properties suitable for gradual changes of the spectral UV-B illumination of artificial lighting. Using a distinct set of lamps and filter glasses an acceptable simulation of the UV-B part of natural global radiation can be achieved. The aging of these and other filter materials under the extreme UV radiation in the lamphouse of a solar simulator is presently unavoidable. This instability can be dealt with only by a precise spectral monitoring and by replacing the filters accordingly. For this reason attempts would be useful to develop real ozone filters which can replace glass filters. In any case chamber experiments require a careful selection of the filter material used and must be accompanied by a continuous UV-B monitoring.

Copernicus ultraviolet observations of mass-loss effects in O and B stars

NASA Technical Reports Server (NTRS)

Snow, T. P., Jr.; Morton, D. C.

1976-01-01

Far-UV spectra of 47 O, B, and A stars obtained with the Copernicus satellite are examined for P Cygni profiles. For all 40 stars with displaced absorption lines, values are given for the velocities of the short-wavelength edge, the line center, and the emission peak (if present). Parts of the spectra of 42 stars are reproduced, evidence for mass motions in ground-based spectra is discussed, and the best available data are summarized on the wavelengths and oscillator strengths of most lines likely to show mass-loss effects in either visual or UV spectra. The main conclusions are that: (1) the far-UV transitions, especially resonance lines, show that mass flow is present over a much wider group of stars than revealed by visible data on subordinate lines; (2) most of the line shifts imply mass motion away from the stars; (3) mass flow occurs in all but one star brighter than a bolometric magnitude of -6.0; and (4) the observed terminal velocities generally exhibit no significant correlation with temperature, luminosity, gravity, rotational velocity, or line strength.

[Spectroscopic analysis of the interaction of ethanol and acid phosphatase from wheat germ].

PubMed

Xu, Dong-mei; Liu, Guang-shen; Wang, Li-ming; Liu, Wei-ping

2004-11-01

Conformational and activity changes of acid phosphatase from wheat germ in ethanol solutions of different concentrations were measured by fluorescence spectra and differential UV-absorption spectra. The effect of ethanol on kinetics of acid phosphatase was determined by using the double reciprocal plot. The results indicate the ethanol has a significant effect on the activity and conformation of acid phosphatase. The activity of acid phosphatase decreased linearly with increasing the concentration of ethanol. Differential UV-absorption spectra of the enzyme denatured in ethanol solutions showed two positive peaks at 213 and 234 nm, respectively. The peaks on the differential UV-absorption spectra suggested that the conformation of enzyme molecule changed from orderly structure to out-of-order crispation. The fluorescence emission peak intensity of the enzyme gradually strengthened with increasing ethanol concentration, which is in concordance with the conformational change of the microenvironments of tyrosine and tryptophan residues. The results indicate that the expression of the enzyme activity correlates with the stability and integrity of the enzyme conformation to a great degree. Ethanol is uncompetitive inhibitor of acid phosphatase.

Two-dimensional imaging of molecular hydrogen in H2-air diffusion flames using two-photon laser-induced fluorescence

NASA Technical Reports Server (NTRS)

Lempert, W.; Kumar, V.; Glesk, I.; Miles, R.; Diskin, G.

1991-01-01

The use of a tunable ArF laser at 193.26 nm to record simultaneous single-laser-shot, planar images of molecular hydrogen and hot oxygen in a turbulent H2-air diffusion flame. Excitation spectra of fuel and oxidant-rich flame zones confirm a partial overlap of the two-photon H2 and single-photon O2 Schumann-Runge absorption bands. UV Rayleigh scattering images of flame structure and estimated detection limits for the H2 two-photon imaging are also presented.

Laser-induced hydrogen radical removal in UV MALDI-MS allows for the differentiation of flavonoid monoglycoside isomers.

PubMed

Yamagaki, Tohru; Watanabe, Takehiro; Tanaka, Masaki; Sugahara, Kohtaro

2014-01-01

Negative-ion matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectra and tandem mass spectra of flavonoid mono-O-glycosides showed the irregular signals that were 1 and/or 2 Da smaller than the parent deprotonated molecules ([M - H](-)) and the sugar-unit lost fragment ions ([M - Sugar - H](-)). The 1 and/or 2 Da mass shifts are generated with the removing of a neutral hydrogen radical (H*), and/or with the homolytic cleavage of the glycosidic bond, such as [M - H* - H](-), [M - Sugar - H* - H](-), and [M - Sugar - 2H* - H](-). It was revealed that the hydrogen radical removes from the phenolic hydroxy groups on the flavonoids, not from the sugar moiety, because the flavonoid backbones themselves absorb the laser. The glycosyl positions depend on the extent of the hydrogen radical removals and that of the homolytic cleavage of the glycosidic bonds. Flavonoid mono-glycoside isomers were distinguished according to their TOF MS and tandem mass spectra.

Genome-Wide Biases in the Rate and Molecular Spectrum of Spontaneous Mutations in Vibrio cholerae and Vibrio fischeri.

PubMed

Dillon, Marcus M; Sung, Way; Sebra, Robert; Lynch, Michael; Cooper, Vaughn S

2017-01-01

The vast diversity in nucleotide composition and architecture among bacterial genomes may be partly explained by inherent biases in the rates and spectra of spontaneous mutations. Bacterial genomes with multiple chromosomes are relatively unusual but some are relevant to human health, none more so than the causative agent of cholera, Vibrio cholerae Here, we present the genome-wide mutation spectra in wild-type and mismatch repair (MMR) defective backgrounds of two Vibrio species, the low-%GC squid symbiont V. fischeri and the pathogen V. cholerae, collected under conditions that greatly minimize the efficiency of natural selection. In apparent contrast to their high diversity in nature, both wild-type V. fischeri and V. cholerae have among the lowest rates for base-substitution mutations (bpsms) and insertion-deletion mutations (indels) that have been measured, below 10 - 3 /genome/generation. Vibrio fischeri and V. cholerae have distinct mutation spectra, but both are AT-biased and produce a surprising number of multi-nucleotide indels. Furthermore, the loss of a functional MMR system caused the mutation spectra of these species to converge, implying that the MMR system itself contributes to species-specific mutation patterns. Bpsm and indel rates varied among genome regions, but do not explain the more rapid evolutionary rates of genes on chromosome 2, which likely result from weaker purifying selection. More generally, the very low mutation rates of Vibrio species correlate inversely with their immense population sizes and suggest that selection may not only have maximized replication fidelity but also optimized other polygenic traits relative to the constraints of genetic drift. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Enhanced charge transport and photovoltaic performance of PBDTTT-C-T/PC70BM solar cells via UV-ozone treatment.

PubMed

Adhikary, Prajwal; Venkatesan, Swaminathan; Adhikari, Nirmal; Maharjan, Purna P; Adebanjo, Olusegun; Chen, Jihua; Qiao, Qiquan

2013-10-21

In this work, the electron transport layer of PBDTTT-C-T/PC70BM polymer solar cells were subjected to UV-ozone treatment, leading to improved cell performances from 6.46% to 8.34%. The solar cell efficiency reached a maximum of 8.34% after an optimal 5 minute UV-ozone treatment, and then decreased if treated for a longer time. To the best of our knowledge, the mechanism behind the effects of UV-ozone treatment on the improvement of charge transport and cell performance is not fully understood. We have developed a fundamental understanding of the UV-ozone treatment mechanism, which explains both the enhancements in charge transport and photovoltaic performance at an optimal treatment time, and also the phenomenon whereby further treatment time leads to a drop in cell efficiency. Transient photocurrent measurements indicated that the cell charge transport times were 1370 ns, 770 ns, 832 ns, 867 ns, and 1150 ns for the 0 min, 5 min, 10 min, 15 min, and 20 min UV-ozone treatment times, respectively. Therefore the 5 min UV-ozone treatment time led to the shortest transport time and the most efficient charge transport in the cells. The 5 min UV-ozone treated sample exhibited the highest peak intensity (E2) in the Raman spectra of the treated films, at about 437 cm(-1), indicating that it possessed the best wurtzite phase crystallinity of the ZnO films. Further increasing the UV-ozone treatment time from 5 to 20 min induced the formation of p-type defects (e.g. interstitial oxygen atoms), pushing the ZnO Fermi-level further away from the vacuum level, and decreasing the wurtzite crystallinity.

The modification of spectral characteristics of cytostatics by optical beams

NASA Astrophysics Data System (ADS)

Pascu, Mihail Lucian; Brezeanu, Mihail; Carstocea, Benone D.; Voicu, Letitia; Gazdaru, Doina M.; Smarandache, Adriana A.

2004-10-01

Besides the biochemical action of methotrexate (MTX) and 5-fluorouracil (FU) their effect in destroying cancer tumours could be enhanced by exposure to light at different doses. Absorption, excitation and emission spectra of 10-4M - 10-5M MTX solutions in natural saline and sodium hydroxide at pH = 8.4 were measured, while their exposure to coherent and uncoherent light in the visible and near ultraviolet (UV) spectral ranges was made (Hg lamps and Nitrogen pulsed laser radiation were used). Absorption spectra exhibit spectral bands in the range 200 nm - 450 nm. The 200 - 450 nm excitation spectra were measured with emission centered on 470 nm; MTX fluorescence excitation was measured at 390 nm and the emission was detected between 400 nm and 600 nm showing a maximum at 470 nm. Spectra modifications, nonlinearly depending on exposure time (varying from 1 min to 20 min), evidenced MTX photo-dissociation to the fluorescent compound 2,4 diamino-formylpteridine. In the 5-FU case the absorption spectra exhibit bands between 200 nm and 450 nm. The emission fluorescence spectra were measured between 400 nm and 600 nm, with λex = 350 nm for UV Hg lamp and with λex = 360 nm for laser irradiated samples; at irradiation with N2 laser emitted radiation the excitation spectra were measured in the range of 200 nm - 400 nm, with λem = 440 nm. New vascularity rapid destruction was observed for conjunctive impregnated with 5-FU solution whilst exposed to incoherent UV and visible light.

Erbb2 up-regulation of ADAM12 expression accelerates skin cancer progression.

PubMed

Rao, Velidi H; Vogel, Kristen; Yanagida, Jodi K; Marwaha, Nitin; Kandel, Amrit; Trempus, Carol; Repertinger, Susan K; Hansen, Laura A

2015-10-01

Solar ultraviolet (UV) radiation can cause severe damage to the skin and is the primary cause of most skin cancer. UV radiation causes DNA damage leading to mutations and also activates the Erbb2/HER2 receptor through indirect mechanisms involving reactive oxygen species. We hypothesized that Erbb2 activation accelerates the malignant progression of UV-induced skin cancer. Following the induction of benign squamous papillomas by UV exposure of v-ras(Ha) transgenic Tg.AC mice, mice were treated topically with the Erbb2 inhibitor AG825 and tumor progression monitored. AG825 treatment reduced tumor volume, increased tumor regression, and delayed the development of malignant squamous cell carcinoma (SCC). Progression to malignancy was associated with increased Erbb2 and ADAM12 (A Disintegin And Metalloproteinase 12) transcripts and protein, while inhibition of Erbb2 blocked the increase in ADAM12 message upon malignant progression. Similarly, human SCC and SCC cell lines had increased ADAM12 protein and transcripts when compared to normal controls. To determine whether Erbb2 up-regulation of ADAM12 contributed to malignant progression of skin cancer, Erbb2 expression was modulated in cultured SCC cells using forced over-expression or siRNA targeting, demonstrating up-regulation of ADAM12 by Erbb2. Furthermore, ADAM12 transfection or siRNA targeting revealed that ADAM12 increased both the migration and invasion of cutaneous SCC cells. Collectively, these results suggest Erbb2 up-regulation of ADAM12 as a novel mechanism contributing to the malignant progression of UV-induced skin cancer. Inhibition of Erbb2/HER2 reduced tumor burden, increased tumor regression, and delayed the progression of benign skin tumors to malignant SCC in UV-exposed mice. Inhibition of Erbb2 suppressed the increase in metalloproteinase ADAM12 expression in skin tumors, which in turn increased migration and tumor cell invasiveness. © 2014 Wiley Periodicals, Inc.

EFFECT OF THE ANTIMUTAGENS VANILLIN AND CINNAMALDEHYDE ON THE SPONTANEOUS MUTATION SPECTRA OF SALMONELLA TA104

EPA Science Inventory

Effect of the Antimutagens Vanillin and Cinnamaldehyde on the / Spontaneous Mutation Spectra of Salmonella TAlO4

Vanillin (VAN) and cinnamaldehyde (CIN) are dietary antimutagens that, when added to assay plates, reduced the spontaneous mutant frequency in Salmonella typhi...

Protein synthesis and the recovery of both survival and cytoplasmic "petite" mutation in ultraviolet-treated yeast cells. II. Mitochondrial protein synthesis.

PubMed

Heude, M; Chanet, R

1975-04-01

The contribution of mitochondrial proteins in the repair of UV-induced lethal and cytoplasmic genetic damages was studied in dark liquid held exponential and stationary phase yeast cells. This was performed by using the specific inhibitors, erythromycin (ER) anc chloramphenicol (CAP). It was shown that mitochondrial proteins are involved in the recovery of stationary phase cells. Mitochondrial proteins are partly implicated in the mechanisms leading to the restoration of the (see article) genotype in UV-irradiated dark liquid held exponential phase cells. Here again, in stationary phase cells, mitochondrial enzymes do not seem to participate in the negative liquid holding (NLH) process for the (see article) induction, as shown by inhibiting mitochondrial protein synthesis or both mitochondrial and nuclear protein synthesis. When cells are grown in glycerol, the response after dark liquid holding of UV-treated cells in the different growth stages are similar to that found for glucose-grown cells. In other words, the fate of cytoplasmic genetic damage, in particular, is not correlated with the repressed or derepressed state of the mitochondria.

Catalogue of UV sources in the Galaxy

NASA Astrophysics Data System (ADS)

Beitia-Antero, L.; Gómez de Castro, A. I.

2017-03-01

The Galaxy Evolution Explorer (GALEX) ultraviolet (UV) database contains the largest photometric catalogue in the ultraviolet range; as a result GALEX photometric bands, Near UV band (NUV) and the Far UV band (FUV), have become standards. Nevertheless, the GALEX catalogue does not include bright UV sources due to the high sensitivity of its detectors, neither sources in the Galactic plane. In order to extend the GALEX database for future UV missions, we have obtained synthetic FUV and NUV photometry using the database of UV spectra generated by the International Ultraviolet Explorer (IUE). This database contains 63,755 spectra in the low dispersion mode (λ / δ λ ˜ 300) obtained during its 18-year lifetime. For stellar sources in the IUE database, we have selected spectra with high Signal-To-NoiseRatio (SNR) and computed FUV and NUV magnitudes using the GALEX transmission curves along with the conversion equations between flux and magnitudes provided by the mission. Besides, we have performed variability tests to determine whether the sources were variable (during the IUE observations). As a result, we have generated two different catalogues: one for non-variable stars and another one for variable sources. The former contains FUV and NUV magnitudes, while the latter gives the basic information and the FUV magnitude for each observation. The consistency of the magnitudes has been tested using White Dwarfs contained in both GALEX and IUE samples. The catalogues are available through the Centre des Donées Stellaires. The sources are distributed throughout the whole sky, with a special coverage of the Galactic plane.

The Drosophila melanogaster Homologue of the Xeroderma Pigmentosum D Gene Product Is Located in Euchromatic Regions and Has a Dynamic Response to UV Light-induced Lesions in Polytene Chromosomes

PubMed Central

Reynaud, Enrique; Lomelí, Hilda; Vázquez, Martha; Zurita, Mario

1999-01-01

The XPD/ERCC2/Rad3 gene is required for excision repair of UV-damaged DNA and is an important component of nucleotide excision repair. Mutations in the XPD gene generate the cancer-prone syndrome, xeroderma pigmentosum, Cockayne’s syndrome, and trichothiodystrophy. XPD has a 5′- to 3′-helicase activity and is a component of the TFIIH transcription factor, which is essential for RNA polymerase II elongation. We present here the characterization of the Drosophila melanogaster XPD gene (DmXPD). DmXPD encodes a product that is highly related to its human homologue. The DmXPD protein is ubiquitous during development. In embryos at the syncytial blastoderm stage, DmXPD is cytoplasmic. At the onset of transcription in somatic cells and during gastrulation in germ cells, DmXPD moves to the nuclei. Distribution analysis in polytene chromosomes shows that DmXPD is highly concentrated in the interbands, especially in the highly transcribed regions known as puffs. UV-light irradiation of third-instar larvae induces an increase in the signal intensity and in the number of sites where the DmXPD protein is located in polytene chromosomes, indicating that the DmXPD protein is recruited intensively in the chromosomes as a response to DNA damage. This is the first time that the response to DNA damage by UV-light irradiation can be visualized directly on the chromosomes using one of the TFIIH components. PMID:10198066

Effect of C5-Methylation of Cytosine on the UV-Induced Reactivity of Duplex DNA: Conformational and Electronic Factors.

PubMed

Banyasz, Akos; Esposito, Luciana; Douki, Thierry; Perron, Marion; Lepori, Clément; Improta, Roberto; Markovitsi, Dimitra

2016-05-12

C5-methylation of cytosines is strongly correlated with UV-induced mutations detected in skin cancers. Mutational hot-spots appearing at TCG sites are due to the formation of pyrimidine cyclobutane dimers (CPDs). The present study, performed for the model DNA duplex (TCGTA)3·(TACGA)3 and the constitutive single strands, examines the factors underlying the effect of C5-methylation on pyrimidine dimerization at TCG sites. This effect is quantified for the first time by quantum yields ϕ. They were determined following irradiation at 255, 267, and 282 nm and subsequent photoproduct analysis using HPLC coupled to mass spectrometry. C5-methylation leads to an increase of the CPD quantum yield up to 80% with concomitant decrease of that of pyrimidine(6-4) pyrimidone adducts (64PPs) by at least a factor of 3. The obtained ϕ values cannot be explained only by the change of the cytosine absorption spectrum upon C5-methylation. The conformational and electronic factors that may affect the dimerization reaction are discussed in light of results obtained by fluorescence spectroscopy, molecular dynamics simulations, and quantum mechanical calculations. Thus, it appears that the presence of an extra methyl on cytosine affects the sugar puckering, thereby enhancing conformations of the TC step that are prone to CPD formation but less favorable to 64PPs. In addition, C5-methylation diminishes the amplitude of conformational motions in duplexes; in the resulting stiffer structure, ππ* excitations may be transferred from initially populated exciton states to reactive pyrimidines giving rise to CPDs.

Correlation fluorescence method of amine detection

NASA Astrophysics Data System (ADS)

Myslitsky, Valentin F.; Tkachuk, Svetlana S.; Rudeichuk, Volodimir M.; Strinadko, Miroslav T.; Slyotov, Mikhail M.; Strinadko, Marina M.

1997-12-01

The amines fluorescence spectra stimulated by UV laser radiation are investigated in this paper. The fluorescence is stimulated by the coherent laser beam with the wavelength 0.337 micrometers . At the sufficient energy of laser stimulation the narrow peaks of the fluorescence spectra are detected besides the wide maximum. The relationship between the fluorescence intensity and the concentration of amines solutions are investigated. The fluorescence intensity temporal dependence on wavelength 0.363 micrometers of the norepinephrine solution preliminarily radiated by UV laser with wavelength 0.337 micrometers was found. The computer stimulated and experimental investigations of adrenaline and norepinephrine mixtures fluorescence spectra were done. The correlation fluorescent method of amines detection is proposed.

METABOLISM, GENOTOXICITY, AND CARCINOGENICITY OF COMFREY

PubMed Central

Mei, Nan; Guo, Lei; Fu, Peter P.; Fuscoe, James C.; Luan, Yang; Chen, Tao

2018-01-01

Comfrey has been consumed by humans as a vegetable and a tea and used as an herbal medicine for more than 2000 years. Comfrey, however, produces hepatotoxicity in livestock and humans and carcinogenicity in experimental animals. Comfrey contains as many as 14 pyrrolizidine alkaloids (PA), including 7-acetylintermedine, 7-acetyllycopsamine, echimidine, intermedine, lasiocarpine, lycopsamine, myoscorpine, symlandine, symphytine, and symviridine. The mechanisms underlying comfrey-induced genotoxicity and carcinogenicity are still not fully understood. The available evidence suggests that the active metabolites of PA in comfrey interact with DNA in liver endothelial cells and hepatocytes, resulting in DNA damage, mutation induction, and cancer development. Genotoxicities attributed to comfrey and riddelliine (a representative genotoxic PA and a proven rodent mutagen and carcinogen) are discussed in this review. Both of these compounds induced similar profiles of 6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP)-derived DNA adducts and similar mutation spectra. Further, the two agents share common mechanisms of drug metabolism and carcinogenesis. Overall, comfrey is mutagenic in liver, and PA contained in comfrey appear to be responsible for comfrey-induced toxicity and tumor induction. PMID:21170807

Inhibitory Effects of Hydroethanolic Leaf Extracts of Kalanchoe brasiliensis and Kalanchoe pinnata (Crassulaceae) against Local Effects Induced by Bothrops jararaca Snake Venom

PubMed Central

Fernandes, Júlia Morais; Félix-Silva, Juliana; da Cunha, Lorena Medeiros; Gomes, Jacyra Antunes dos Santos; Siqueira, Emerson Michell da Silva; Gimenes, Luisa Possamai; Lopes, Norberto Peporine; Soares, Luiz Alberto Lira; Fernandes-Pedrosa, Matheus de Freitas; Zucolotto, Silvana Maria

2016-01-01

The species Kalanchoe brasiliensis and Kalanchoe pinnata, both known popularly as “Saião,” are used interchangeably in traditional medicine for their antiophidic properties. Studies evaluating the anti-venom activity of these species are scarce. This study aims to characterize the chemical constituents and evaluate the inhibitory effects of hydroethanolic leaf extracts of K. brasiliensis and K. pinnata against local effects induced by Bothrops jararaca snake venom. Thin Layer Chromatography (TLC) and High Performance Liquid Chromatography coupled with Diode Array Detection and Electrospray Mass Spectrometry (HPLC-DAD-MS/MS) were performed for characterization of chemical markers of the extracts from these species. For antiophidic activity evaluation, B. jararaca venom-induced paw edema and skin hemorrhage in mice were evaluated. In both models, hydroethanolic extracts (125–500 mg/kg) were administered intraperitoneally in different protocols. Inhibition of phospholipase enzymatic activity of B. jararaca was evaluated. The HPLC-DAD-MS/MS chromatographic profile of extracts showed some particularities in the chemical profile of the two species. K. brasileinsis exhibited major peaks that have UV spectra similar to flavonoid glycosides derived from patuletin and eupafolin, while K. pinnata showed UV spectra similar to flavonoids glycosides derived from quercetin and kaempferol. Both extracts significantly reduced the hemorrhagic activity of B. jararaca venom in pre-treatment protocol, reaching about 40% of inhibition, while only K. pinnata was active in post-treatment protocol (about 30% of inhibition). In the antiedematogenic activity, only K. pinnata was active, inhibiting about 66% and 30% in pre and post-treatment protocols, respectively. Both extracts inhibited phospholipase activity; however, K. pinnata was more active. In conclusion, the results indicate the potential antiophidic activity of Kalanchoe species against local effects induced by B. jararaca snake venom, suggesting their potential use as a new source of bioactive molecules against bothropic venom. PMID:28033347

Inhibitory Effects of Hydroethanolic Leaf Extracts of Kalanchoe brasiliensis and Kalanchoe pinnata (Crassulaceae) against Local Effects Induced by Bothrops jararaca Snake Venom.

PubMed

Fernandes, Júlia Morais; Félix-Silva, Juliana; da Cunha, Lorena Medeiros; Gomes, Jacyra Antunes Dos Santos; Siqueira, Emerson Michell da Silva; Gimenes, Luisa Possamai; Lopes, Norberto Peporine; Soares, Luiz Alberto Lira; Fernandes-Pedrosa, Matheus de Freitas; Zucolotto, Silvana Maria

2016-01-01

The species Kalanchoe brasiliensis and Kalanchoe pinnata, both known popularly as "Saião," are used interchangeably in traditional medicine for their antiophidic properties. Studies evaluating the anti-venom activity of these species are scarce. This study aims to characterize the chemical constituents and evaluate the inhibitory effects of hydroethanolic leaf extracts of K. brasiliensis and K. pinnata against local effects induced by Bothrops jararaca snake venom. Thin Layer Chromatography (TLC) and High Performance Liquid Chromatography coupled with Diode Array Detection and Electrospray Mass Spectrometry (HPLC-DAD-MS/MS) were performed for characterization of chemical markers of the extracts from these species. For antiophidic activity evaluation, B. jararaca venom-induced paw edema and skin hemorrhage in mice were evaluated. In both models, hydroethanolic extracts (125-500 mg/kg) were administered intraperitoneally in different protocols. Inhibition of phospholipase enzymatic activity of B. jararaca was evaluated. The HPLC-DAD-MS/MS chromatographic profile of extracts showed some particularities in the chemical profile of the two species. K. brasileinsis exhibited major peaks that have UV spectra similar to flavonoid glycosides derived from patuletin and eupafolin, while K. pinnata showed UV spectra similar to flavonoids glycosides derived from quercetin and kaempferol. Both extracts significantly reduced the hemorrhagic activity of B. jararaca venom in pre-treatment protocol, reaching about 40% of inhibition, while only K. pinnata was active in post-treatment protocol (about 30% of inhibition). In the antiedematogenic activity, only K. pinnata was active, inhibiting about 66% and 30% in pre and post-treatment protocols, respectively. Both extracts inhibited phospholipase activity; however, K. pinnata was more active. In conclusion, the results indicate the potential antiophidic activity of Kalanchoe species against local effects induced by B. jararaca snake venom, suggesting their potential use as a new source of bioactive molecules against bothropic venom.

Photo-Oxidative Stress-Driven Mutagenesis and Adaptive Evolution on the Marine Diatom Phaeodactylum tricornutum for Enhanced Carotenoid Accumulation.

PubMed

Yi, Zhiqian; Xu, Maonian; Magnusdottir, Manuela; Zhang, Yuetuan; Brynjolfsson, Sigurdur; Fu, Weiqi

2015-09-29

Marine diatoms have recently gained much attention as they are expected to be a promising resource for sustainable production of bioactive compounds such as carotenoids and biofuels as a future clean energy solution. To develop photosynthetic cell factories, it is important to improve diatoms for value-added products. In this study, we utilized UVC radiation to induce mutations in the marine diatom Phaeodactylum tricornutum and screened strains with enhanced accumulation of neutral lipids and carotenoids. Adaptive laboratory evolution (ALE) was also used in parallel to develop altered phenotypic and biological functions in P. tricornutum and it was reported for the first time that ALE was successfully applied on diatoms for the enhancement of growth performance and productivity of value-added carotenoids to date. Liquid chromatography-mass spectrometry (LC-MS) was utilized to study the composition of major pigments in the wild type P. tricornutum, UV mutants and ALE strains. UVC radiated strains exhibited higher accumulation of fucoxanthin as well as neutral lipids compared to their wild type counterpart. In addition to UV mutagenesis, P. tricornutum strains developed by ALE also yielded enhanced biomass production and fucoxanthin accumulation under combined red and blue light. In short, both UV mutagenesis and ALE appeared as an effective approach to developing desired phenotypes in the marine diatoms via electromagnetic radiation-induced oxidative stress.

Photo-Oxidative Stress-Driven Mutagenesis and Adaptive Evolution on the Marine Diatom Phaeodactylum tricornutum for Enhanced Carotenoid Accumulation

PubMed Central

Yi, Zhiqian; Xu, Maonian; Magnusdottir, Manuela; Zhang, Yuetuan; Brynjolfsson, Sigurdur; Fu, Weiqi

2015-01-01

Marine diatoms have recently gained much attention as they are expected to be a promising resource for sustainable production of bioactive compounds such as carotenoids and biofuels as a future clean energy solution. To develop photosynthetic cell factories, it is important to improve diatoms for value-added products. In this study, we utilized UVC radiation to induce mutations in the marine diatom Phaeodactylum tricornutum and screened strains with enhanced accumulation of neutral lipids and carotenoids. Adaptive laboratory evolution (ALE) was also used in parallel to develop altered phenotypic and biological functions in P. tricornutum and it was reported for the first time that ALE was successfully applied on diatoms for the enhancement of growth performance and productivity of value-added carotenoids to date. Liquid chromatography-mass spectrometry (LC-MS) was utilized to study the composition of major pigments in the wild type P. tricornutum, UV mutants and ALE strains. UVC radiated strains exhibited higher accumulation of fucoxanthin as well as neutral lipids compared to their wild type counterpart. In addition to UV mutagenesis, P. tricornutum strains developed by ALE also yielded enhanced biomass production and fucoxanthin accumulation under combined red and blue light. In short, both UV mutagenesis and ALE appeared as an effective approach to developing desired phenotypes in the marine diatoms via electromagnetic radiation-induced oxidative stress. PMID:26426027

Conformers, infrared spectrum and UV-induced photochemistry of matrix-isolated furfuryl alcohol.

PubMed

Araujo-Andrade, C; Gómez-Zavaglia, A; Reva, I D; Fausto, R

2012-03-08

The infrared spectra of furfuryl alcohol (2-furanmethanol, FFA) were investigated for FFA monomers isolated in low-temperature argon matrices. The structural interpretation of the obtained experimental spectra was assisted by analysis of the molecule's conformational landscape. According to the DFT(B3LYP)/6-311++G(d,p) calculations, five different minimum energy structures were found on the potential energy surface of the molecule. They can be defined by the orientation of the OCCO and CCOH dihedral angles: GG', GG, TG, TT, GT (G = +gauche, G' = -gauche, T = trans) and have a symmetry equivalent configuration: GG' = G'G, GG = G'G', TG = TG', GT = G'T. When zero-point energies are taken into account, only three (GG', GG, and TT) out of the five unique minima correspond to stable structures. The most stable conformer GG' (OCCO, 72.7°; CCOH, -59.3°), which in gas phase at room temperature accounts for ∼65% of the total population, was the only form isolated in the argon matrices at 14 K. The other two relevant forms convert into conformer GG' during matrix deposition. The low temperature glassy and crystalline states of FFA were also obtained and their infrared spectra assigned, suggesting the sole existence of the GG' conformer also in these phases. The photochemical behavior of FFA induced in situ, by tunable UV-laser, was also studied. The longest wavelength resulting in photochemical changes in the structure of the irradiated sample was found to be λ = 229 nm. Such UV irradiation of the matrix-isolated FFA led to production of formaldehyde and different isomeric C(4)H(4)O species. Cycloprop-2-ene-1-carbaldehyde and buta-2,3-dienal (two conformers) are the main initial C(4)H(4)O photoproducts formed upon short-time excitation at λ = 229 nm. But-3-ynal (two conformers) was the principal photoproduct resulting from prolonged excitation at λ= 229 nm, being consumed upon irradiation at shorter wavelengths (λ < 227.5 nm). Vinyl ketene is produced from FFA in the trans conformation and undergoes isomerization to the cis form upon irradiation at λ < 227.5 nm. Cyclopropene, propyne, allene, and CO were also identified in the irradiated matrices (in particular at the later stages of irradiation), suggesting that the photoproduced aldehydes partially decarbonylate during the performed photochemical experiments.

NORF5/HUG1 is a component of the MEC1-mediated checkpoint response to DNA damage and replication arrest in Saccharomyces cerevisiae.

PubMed

Basrai, M A; Velculescu, V E; Kinzler, K W; Hieter, P

1999-10-01

Analysis of global gene expression in Saccharomyces cerevisiae by the serial analysis of gene expression technique has permitted the identification of at least 302 previously unidentified transcripts from nonannotated open reading frames (NORFs). Transcription of one of these, NORF5/HUG1 (hydroxyurea and UV and gamma radiation induced), is induced by DNA damage, and this induction requires MEC1, a homolog of the ataxia telangiectasia mutated (ATM) gene. DNA damage-specific induction of HUG1, which is independent of the cell cycle stage, is due to the alleviation of repression by the Crt1p-Ssn6p-Tup1p complex. Overexpression of HUG1 is lethal in combination with a mec1 mutation in the presence of DNA damage or replication arrest, whereas a deletion of HUG1 rescues the lethality due to a mec1 null allele. HUG1 is the first example of a NORF with important biological functional properties and defines a novel component of the MEC1 checkpoint pathway.

Advances in radiation mutagenesis through studies on Drosophila

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muller, H. J.

The approximately linear relation between radiation dose and induced lethals, known for Drosophila spermatozoa, is now extended to spermatids. Data are included regarding oogonia. The linearity principle has been confirmed for minute structural changes in spermatozoa. The dependence of gross structural changes, as multi-hit events, on about the 1.5 power of the dose, long known for spermatozoa, is now extended to spermatids and late oocytes, for relatively short exposures. However, these stages unlike spermatozoa are found to allow union of broken chromosomes. Therefore, the frequencies are lower for more dispersed exposures of these stages, and the precise dose relation variesmore » with the timing. Part of the dominant and even recessive lethals induced in late oocytes follow the same frequency pattern and therefore are multi-hit events. Yet there is a much lower chance after oocytic than spermatozoan irradiation that two broken ends derived from different hits will unite, hence most such unions are nonreciprocal. The following is the order of decreasing radiation mutability of different stages found by ourselves and others: spermatids, spermatozoa in females, spermatozoa 0 to 1 day before ejaculation, earlier spermatozoa, late oocytes, gonia of either sex. Lethal frequencies for these stages range over approximately an order of magnitude, gross structural changes far more widely. Of potential usefulness is our extension of the principle of marked reduction of radiation mutagenesis by anoxia, known for spermatozoa in adult males, to those in pupal males and in females to spermatids and to oocytes. In spermatids this reduction is especially marked but the increase caused by substituting oxygen for air is less marked, perhaps because of enzymatic differences. In contrast, the induction of gross structural changes in oocytes, but not in spermatids, is markedly reduced by oxygen post-treatment; it is increased by dehydration. The efficacy of induction of structural changes by treatment of spermatozoa, whether with radiation or chemical mutagens, is correlated with the conditions of sperm utilization and egg production. Improving our perspective on radiation effects, some 800,000 offspring have been scored for spontaneous visible mutations of 13 specific loci. The average point-mutation rate was 0.5 to 1.0 per locus among 10/sup 5/ germ cells. Most mutations occurred in peri-fertilization stages. All loci studied mutated from one to nine times. Loci mutating oftener spontaneously also gave more radiation mutation, in other studies. Spectra of individual loci prove similar for spontaneous and induced mutation. Studies on back-mutations also showed similarity of spontaneous and radiation mutations. The doubling dose for back-mutations of forked induced in spermatozoa was several hundred roentgens, similar to that for direct point-mutations induced in gonia at diverse loci. Recent analyses of human mutational load lead to mutation-rate estimates like those earlier based on extrapolations from Drosophila, thus supporting the significance for man of the present studies. (auth)« less

Ultraviolet Spectroscopy of Supernovae: The First Two Years of Swift Observations

NASA Technical Reports Server (NTRS)

Immler, Stefan

2008-01-01

We present the entire sample of ultraviolet (1JV) spectra of supernovae (SNe) obtained with the Ultraviolet/Optical Telescope (UVOT) on board the Swift satellite during the first 2 years of observations (2005/2006). A total of 31 UV-grism and 22 V-grism spectra of 9 supernovae (SNe) have been collected. of which 6 are thermonuclear (type Ia) and 3 core collapse (type Ibc/II) SNe. All the spectra have been obtained during the photospheric phase. After a comparison of the spectra of our sample with those in the literature (SNe 1992A. 1990N and 1999em). we confirm some degree of diversity in the UV emission of Type Ia SNe and a greater homogeneity in the Type I1 Plateau SN sample. Signatures of interaction between the ejecta and the circumstellar environment have been found in the UV spectrum of SN 2006jc, the only SN Type Ib/c for which UVOT grism data are available. Currently, Swift LJVOT is the best suited instrument for early SN studies in the UV due to its fast response and flexible scheduling capabilities. However. in order to increase the quality of the data and significantly improve our understanding of the lJV properties of SNe and to fully maximize the scientific potential of UVOT grism observations. a larger investment in obsening time and longer exposures are needed.

Hypomorphic PCNA mutation underlies a human DNA repair disorder

PubMed Central

Baple, Emma L.; Chambers, Helen; Cross, Harold E.; Fawcett, Heather; Nakazawa, Yuka; Chioza, Barry A.; Harlalka, Gaurav V.; Mansour, Sahar; Sreekantan-Nair, Ajith; Patton, Michael A.; Muggenthaler, Martina; Rich, Phillip; Wagner, Karin; Coblentz, Roselyn; Stein, Constance K.; Last, James I.; Taylor, A. Malcolm R.; Jackson, Andrew P.; Ogi, Tomoo; Lehmann, Alan R.; Green, Catherine M.; Crosby, Andrew H.

2014-01-01

Numerous human disorders, including Cockayne syndrome, UV-sensitive syndrome, xeroderma pigmentosum, and trichothiodystrophy, result from the mutation of genes encoding molecules important for nucleotide excision repair. Here, we describe a syndrome in which the cardinal clinical features include short stature, hearing loss, premature aging, telangiectasia, neurodegeneration, and photosensitivity, resulting from a homozygous missense (p.Ser228Ile) sequence alteration of the proliferating cell nuclear antigen (PCNA). PCNA is a highly conserved sliding clamp protein essential for DNA replication and repair. Due to this fundamental role, mutations in PCNA that profoundly impair protein function would be incompatible with life. Interestingly, while the p.Ser228Ile alteration appeared to have no effect on protein levels or DNA replication, patient cells exhibited marked abnormalities in response to UV irradiation, displaying substantial reductions in both UV survival and RNA synthesis recovery. The p.Ser228Ile change also profoundly altered PCNA’s interaction with Flap endonuclease 1 and DNA Ligase 1, DNA metabolism enzymes. Together, our findings detail a mutation of PCNA in humans associated with a neurodegenerative phenotype, displaying clinical and molecular features common to other DNA repair disorders, which we showed to be attributable to a hypomorphic amino acid alteration. PMID:24911150

Defective removal of ribonucleotides from DNA promotes systemic autoimmunity

PubMed Central

Günther, Claudia; Kind, Barbara; Reijns, Martin A.M.; Berndt, Nicole; Martinez-Bueno, Manuel; Wolf, Christine; Tüngler, Victoria; Chara, Osvaldo; Lee, Young Ae; Hübner, Norbert; Bicknell, Louise; Blum, Sophia; Krug, Claudia; Schmidt, Franziska; Kretschmer, Stefanie; Koss, Sarah; Astell, Katy R.; Ramantani, Georgia; Bauerfeind, Anja; Morris, David L.; Cunninghame Graham, Deborah S.; Bubeck, Doryen; Leitch, Andrea; Ralston, Stuart H.; Blackburn, Elizabeth A.; Gahr, Manfred; Witte, Torsten; Vyse, Timothy J.; Melchers, Inga; Mangold, Elisabeth; Nöthen, Markus M.; Aringer, Martin; Kuhn, Annegret; Lüthke, Kirsten; Unger, Leonore; Bley, Annette; Lorenzi, Alice; Isaacs, John D.; Alexopoulou, Dimitra; Conrad, Karsten; Dahl, Andreas; Roers, Axel; Alarcon-Riquelme, Marta E.; Jackson, Andrew P.; Lee-Kirsch, Min Ae

2014-01-01

Genome integrity is continuously challenged by the DNA damage that arises during normal cell metabolism. Biallelic mutations in the genes encoding the genome surveillance enzyme ribonuclease H2 (RNase H2) cause Aicardi-Goutières syndrome (AGS), a pediatric disorder that shares features with the autoimmune disease systemic lupus erythematosus (SLE). Here we determined that heterozygous parents of AGS patients exhibit an intermediate autoimmune phenotype and demonstrated a genetic association between rare RNASEH2 sequence variants and SLE. Evaluation of patient cells revealed that SLE- and AGS-associated mutations impair RNase H2 function and result in accumulation of ribonucleotides in genomic DNA. The ensuing chronic low level of DNA damage triggered a DNA damage response characterized by constitutive p53 phosphorylation and senescence. Patient fibroblasts exhibited constitutive upregulation of IFN-stimulated genes and an enhanced type I IFN response to the immunostimulatory nucleic acid polyinosinic:polycytidylic acid and UV light irradiation, linking RNase H2 deficiency to potentiation of innate immune signaling. Moreover, UV-induced cyclobutane pyrimidine dimer formation was markedly enhanced in ribonucleotide-containing DNA, providing a mechanism for photosensitivity in RNase H2–associated SLE. Collectively, our findings implicate RNase H2 in the pathogenesis of SLE and suggest a role of DNA damage–associated pathways in the initiation of autoimmunity. PMID:25500883

Preparation and spectral properties of europium hydrogen squarate microcrystals

NASA Astrophysics Data System (ADS)

Kolev, T.; Danchova, N.; Shandurkov, D.; Gutzov, S.

2018-04-01

A simple scheme for preparation of europium hydrogen squarate octahydrate microcrystals, Eu(HSq)3·8H2O is demonstrated. The microcrystalline powders obtained have a potential application as non-centrosymmetric and UV radiation - protective hybrid optical material. The site-symmetry of the Eu - ion is C2V or lower, obtained from diffuse reflectance spectra. The formation of europium hydrogen squarate is supported by IR - spectroscopy, UV-vis spectroscopy, chemical analysis and X-ray diffraction. A detailed analysis of the UV-vis and IR spectra of the micropowders prepared is presented. The reaction between europium oxide and squaric acid leads to formation of microcrystalline plate-like crystals of europium hydrogen squarate Eu(HSq)3·8H2O, a non-centrosymmetric hybrid optical material with a potential application as UV radiation - protective coatings.

Fermi Level Control of Point Defects During Growth of Mg-Doped GaN

NASA Astrophysics Data System (ADS)

Bryan, Zachary; Hoffmann, Marc; Tweedie, James; Kirste, Ronny; Callsen, Gordon; Bryan, Isaac; Rice, Anthony; Bobea, Milena; Mita, Seiji; Xie, Jinqiao; Sitar, Zlatko; Collazo, Ramón

2013-05-01

In this study, Fermi level control of point defects during metalorganic chemical vapor deposition (MOCVD) of Mg-doped GaN has been demonstrated by above-bandgap illumination. Resistivity and photoluminescence (PL) measurements are used to investigate the Mg dopant activation of samples with Mg concentration of 2 × 1019 cm-3 grown with and without exposure to ultraviolet (UV) illumination. Samples grown under UV illumination have five orders of magnitude lower resistivity values compared with typical unannealed GaN:Mg samples. The PL spectra of samples grown with UV exposure are similar to the spectra of those grown without UV exposure that were subsequently annealed, indicating a different incorporation of compensating defects during growth. Based on PL and resistivity measurements we show that Fermi level control of point defects during growth of III-nitrides is feasible.

Tomographic separation of composite spectra. 2: The components of 29 UW Canis Majoris

NASA Technical Reports Server (NTRS)

Bagnuolo, William G., Jr.; Gies, Douglas R.; Hahula, Michael E.; Wiemker, Rafael; Wiggs, Michael S.

1994-01-01

We have analyzed the UV photospheric lines of 29 CMa, a 4.39 day period, double-lined O-type spectroscopic binary. Archival data from International Ultraviolet Explorer (IUE)(28 spectra well distributed in oribital phase) were analyzed with several techniques. We find that the mass ratio is q = 1.20 +/- 0.16 (secondary more massive) based on three independent arguments. A tomography algorithm was used to produce the separate spectra of the two stars in six UV spectral regions. The MK spectral classifications of the primary and secondary, O7.5-8 Iab and O9.7 Ib, respectively, were estimated through a comparison of UV line ratios with those in spectral standard stars. The flux ratio of the stars in the UV is 0.36 +/- 0.07 (primary brighter). The primary has a strong P Cygni NIV wavelength 1718 feature, indicating a strong stellar wind. We also present tomographic reconstructions of visual spectral data in the range 4300-4950 A, based on seven observations of differing orbital phases, which confirm the UV classifications, and show that the primary is an Of star. From the spectral classifications, we estimate the temperatures of the stars to be 33,750 K and 29,000 K for primary and secondary, respectively. We then fit visual and UV light curves and show that reasonably good fits can be obtained with these temperatures, a semicontact configuration, an inclination of 74 deg. +/- 2 deg., and an intensity ratio r is less than 0.5.

ACTION OF MUTAGENIC AGENTS ON AUXOTROPHIC STRAINS OF STREPTOMYCES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jarai, M.

1962-01-01

The mutagenic effect on Streptomyces auxotrophs of uv and x irradiation and of some chemical agerts was studied. From the observed reverse mutations it was concluded that uv and probably x irradiation have an optimal mutagenic dose. With nine auxotrophic strains it was shown that under the same conditions different gene loci reacted differently to the same mutagenic agent. With uy radiation, mutations occurred most frequently at doses falling within the range of 3500 to 4000 erg/mm/sup 2/. With such doses, the average mutation frequency for singly deficient mutants was 0.8 x 10/sup -6/, for doubly deficient mutants 8.4 xmore » 10/sup -8/. An analysis of the number of mutations as compared to the number of survivors in two biochemical mutants (N-4 and N-11) showed that with N- 4 the highest number of mutations was obtained at doses of 3500 to 4500 erg/mm/ sup 2/, namely, 12 to 15 per 10 surviving conidia, and with strain N-11, the highest frequency was obtained in the same dose range, namely, three to four mutations per 10/sup 6/ surviving conidia. The optimal dose of irradiation corresponds to 90 to 97% lethality. It was shown that, unlike the results with uv irradiation, with x rays no such definite relation existed between optimal dose and frequency of mutations. The highest mutation frequency occurred at doses of 20,000 to 25,000 r, which corresponded to 85 to 91% lethality. Of the chemical substances examined, a definite mutagenic action was exerted by acridine orange, streptomycin, hydroxylamine, phenyl, isocyannte, and 8-quinolinol. The maximum mutagenic frequency for survivors was 41.4 x 10/sup -6/ after uv irradiation (biochemical mutant arg 3-; frequency of sportaneous back mutation, 0.041 x 10/sup -6/). With x irradiation the maximum mutagenic frequency was 3.42 x 10/sup -6/ (biochemical mutant meth 1-; frequency of spontaneous back mutation, 0.28 X 10/sup -6/). With chemical agents the maximum mutation frequencies for the initial conidia number were as follows: acridine orange, 3.65 x 10/sup -6/ (biochemical mutant arg 3-); streptomycin, 2.05 x 10/sup -6/ (biochemical mutant arg 3-); hydroxylamine, 5.81 x 10/sup -6/ (biochemical mutant meth 1/sup -/); phenyl isocyanate, 6.11 x 10/sup -6/ (biochemical mutant meth 1/sup -/); 8- quinolinol, 1.02 x 10/sup -6/ (biochemical mutant meth 1/sup -/). (BBB)« less

The PSO4 gene is responsible for an error-prone recombinational DNA repair pathway in Saccharomyces cerevisiae.

PubMed

de Andrade, H H; Marques, E K; Schenberg, A C; Henriques, J A

1989-06-01

The induction of mitotic gene conversion and crossing-over in Saccharomyces cerevisiae diploid cells homozygous for the pso4-1 mutation was examined in comparison to the corresponding wild-type strain. The pso4-1 mutant strain was found to be completely blocked in mitotic recombination induced by photoaddition of mono- and bifunctional psoralen derivatives as well as by mono- (HN1) and bifunctional (HN2) nitrogen mustards or 254 nm UV radiation in both stationary and exponential phases of growth. Concerning the lethal effect, diploids homozygous for the pso4-1 mutation are more sensitive to all agents tested in any growth phase. However, this effect is more pronounced in the G2 phase of the cell cycle. These results imply that the ploidy effect and the resistance of budding cells are under the control of the PSO4 gene. On the other hand, the pso4-1 mutant is mutationally defective for all agents used. Therefore, the pso4-1 mutant has a generalized block in both recombination and mutation ability. This indicates that the PSO4 gene is involved in an error-prone repair pathway which relies on a recombinational mechanism, strongly suggesting an analogy between the pso4-1 mutation and the RecA or LexA mutation of Escherichia coli.

Computing UV/vis spectra using a combined molecular dynamics and quantum chemistry approach: bis-triazin-pyridine (BTP) ligands studied in solution.

PubMed

Höfener, Sebastian; Trumm, Michael; Koke, Carsten; Heuser, Johannes; Ekström, Ulf; Skerencak-Frech, Andrej; Schimmelpfennig, Bernd; Panak, Petra J

2016-03-21

We report a combined computational and experimental study to investigate the UV/vis spectra of 2,6-bis(5,6-dialkyl-1,2,4-triazin-3-yl)pyridine (BTP) ligands in solution. In order to study molecules in solution using theoretical methods, force-field parameters for the ligand-water interaction are adjusted to ab initio quantum chemical calculations. Based on these parameters, molecular dynamics (MD) simulations are carried out from which snapshots are extracted as input to quantum chemical excitation-energy calculations to obtain UV/vis spectra of BTP ligands in solution using time-dependent density functional theory (TDDFT) employing the Tamm-Dancoff approximation (TDA). The range-separated CAM-B3LYP functional is used to avoid large errors for charge-transfer states occurring in the electronic spectra. In order to study environment effects with theoretical methods, the frozen-density embedding scheme is applied. This computational procedure allows to obtain electronic spectra calculated at the (range-separated) DFT level of theory in solution, revealing solvatochromic shifts upon solvation of up to about 0.6 eV. Comparison to experimental data shows a significantly improved agreement compared to vacuum calculations and enables the analysis of relevant excitations for the line shape in solution.

Garlic Supplementation Ameliorates UV-Induced Photoaging in Hairless Mice by Regulating Antioxidative Activity and MMPs Expression.

PubMed

Kim, Hye Kyung

2016-01-08

UV exposure is associated with oxidative stress and is the primary factor in skin photoaging. UV-induced reactive oxygen species (ROS) cause the up-regulation of metalloproteinase (MMPs) and the degradation of dermal collagen and elastic fibers. Garlic and its components have been reported to exert antioxidative effects. The present study investigated the protective effect of garlic on UV-induced photoaging and MMPs regulation in hairless mice. Garlic was supplemented in the diet, and Skh-1 hairless mice were exposed to UV irradiation five days/week for eight weeks. Mice were divided into four groups; Non-UV, UV-irradiated control, UV+1% garlic powder diet group, and UV+2% garlic powder diet group. Chronic UV irradiation induced rough wrinkling of the skin with hyperkeratosis, and administration of garlic diminished the coarse wrinkle formation. UV-induced dorsal skin and epidermal thickness were also ameliorated by garlic supplementation. ROS generation, skin and serum malondialdehyde levels were significantly increased by UV exposure and were ameliorated by garlic administration although the effects were not dose-dependent. Antioxidant enzymes such as superoxide dismutase and catalase activities in skin tissues were markedly reduced by UV irradiation and garlic treatment increased these enzyme activities. UV-induced MMP-1 and MMP-2 protein levels were suppressed by garlic administration. Furthermore, garlic supplementation prevented the UV-induced increase of MMP-1 mRNA expression and the UV-induced decrease of procollagen mRNA expression. These results suggest that garlic may be effective for preventing skin photoaging accelerated by UV irradiation through the antioxidative system and MMP regulation.

Insights into the activity change of spore photoproduct lyase induced by mutations at a peripheral glycine residue

NASA Astrophysics Data System (ADS)

Yang, Linlin; Li, Lei

2017-03-01

UV radiation triggers the formation of 5-thyminyl-5,6-dihydrothymine, i.e. the spore photoproduct (SP), in the genomic DNA of bacterial endospores. These SPs, if not repaired in time, may lead to genome instability and cell death. SP is mainly repaired by spore photoproduct lyase (SPL) during spore outgrowth via an unprecedented protein-harbored radical transfer pathway that is composed of at least a cysteine and two tyrosine residues. This mechanism is consistent with the recently solved SPL structure that shows all three residues are located in proximity and thus able to participate in the radical transfer process during the enzyme catalysis. In contrast, an earlier in vivo mutational study identified a glycine to arginine mutation at the position 168 on the B. subtilis SPL that was later found to be > 15 Å away from the enzyme active site. This mutation appears to abolish the enzyme activity because endospores carrying this mutant were sensitive to UV light. To understand the molecular basis for this rendered enzyme activity, we constructed two SPL mutations G168A and G168R, examined their repair of dinucleotide SP TpT, and found that both mutants exhibit reduced enzyme activity. Comparing with the wildtype (WT) SPL enzyme, the G168A mutant slows down the SP TpT repair by 3 4 fold while the G168R mutant by 80 fold. Both mutants exhibit a smaller apparent (DV) kinetic isotope effect (KIE) but a bigger competitive (DV/K) KIE than that by the WT SPL. Moreover, the G168R mutant also produces a large portion of the abortive repair product TpT-SO2-; the formation of which indicates that cysteine 141 is no longer well positioned as the H-donor to the thymine allylic radical intermediate. All these data imply that the mutation at the remote glycine 168 residue alters the enzyme 3D structure, subsequently reducing the SPL activity by changing the positions of the essential amino acids involved in the radical transfer process.

Conformational Specific Infrared and Ultraviolet Spectroscopy of Cold YA(D-Pro)AA\\cdotH+ Ions: a Sterochemical "twist" on the Proline Effect

NASA Astrophysics Data System (ADS)

Harrilal, Christopher P.; DeBlase, Andrew F.; Burke, Nicole L.; McLuckey, Scott A.; Zwier, Timothy S.

2016-06-01

The "proline effect" is a well-known fragmentation phenomenon in mass spectrometry, in which y-fragments are produced preferentially over b-fragments during the collision induced dissociation of protonated L-proline containing peptide ions. This specific fragmentation channel is favored because of the high basicity of the secondary amine intermediate and the ring instability in alternative bn+ products [ASMS 2014, 25, 1705]. In contrast, peptides containing the D-Pro stereoisomer have been shown to largely favor the production of b4+ ions over y3+ ions. This strongly suggests that differences in the conformational preferences between the D-Pro and L-Pro diastereomers are likely to be responsible but structural evidence has been lacking to date. Using tandem mass spectrometry and IR-UV double resonant action spectroscopy we are able to compare the 3D structures of cold [YA(D-Pro)AA+H]+ to [YA(L-Pro)AA+H]+ ions. The UV action spectra reveals two major conformers in [YA(D-Pro)AA+H]+ and one major conformer in [YA(L-Pro)AA+H]+. Clear differences in the hydrogen bonding patterns are apparent between the two conformers observed in the D-Pro specie which are both distinct from the L-Pro diastereomer. Furthermore, conformer and diastereomer specific photofragmentation patterns are observed. It is also noted that a ten-fold photofragment enhancement unique to one of the D-Pro conformers is observed upon absorption of a resonant IR photon after UV excitation. Differences in the excited state photophysics between the two D-Pro conformers suggest that vibrational excitation of S1 turns on coupling to the dissociative -Tyr channel in one conformer, while this coupling is already present in the vibronic ground state of the other. Calculated harmonic spectra (M052X/6-31+G*) of conformers obtained from Monte Carlo searches to the experimental spectra.

X-Ray, UV and Optical Observations of Classical Cepheids: New Insights into Cepheid Evolution, and the Heating and Dynamics of Their Atmospheres

NASA Astrophysics Data System (ADS)

Engle, Scott G.; Guinan, Edward F.

2012-06-01

To broaden the understanding of classical Cepheid structure, evolution and atmospheres, we have extended our continuing secret lives of Cepheids program by obtaining XMM/Chandra X-ray observations, and Hubble space telescope (HST) / cosmic origins spectrograph (COS) FUV-UV spectra of the bright, nearby Cepheids Polaris, δ Cep and β Dor. Previous studies made with the international ultraviolet explorer (IUE) showed a limited number of UV emission lines in Cepheids. The well-known problem presented by scattered light contamination in IUE spectra for bright stars, along with the excellent sensitivity & resolution combination offered by HST/COS, motivated this study, and the spectra obtained were much more rich and complex than we had ever anticipated. Numerous emission lines, indicating 10^4 K up to ~3 x 10^5 K plasmas, have been observed, showing Cepheids to have complex, dynamic outer atmospheres that also vary with the photospheric pulsation period. The FUV line emissions peak in the phase range φ ∼ 0.8-1.0 and vary by factors as large as 10x. A more complete picture of Cepheid outer atmospheres is accomplished when the HST/COS results are combined with X-ray observations that we have obtained of the same stars with XMM-Newton & Chandra. The Cepheids detected to date have X-ray luminosities of log Lx ~ 28.5-29.1 ergs/sec, and plasma temperatures in the 2-8 x 10^6 K range. Given the phase-timing of the enhanced emissions, the most plausible explanation is the formation of a pulsation-induced shocks that excite (and heat) the atmospheric plasmas surrounding the photosphere. A pulsation-driven α^2 equivalent dynamo mechanism is also a viable and interesting alternative. However, the tight phase-space of enhanced emission (peaking near 0.8-1.0 φ) favor the shock heating mechanism hypothesis.

The role of ultraviolet-A reflectance and ultraviolet-A induced fluorescence in the appearance of budgerigar plumage: insights from spectrofluorometry and reflectance spectrophotometry.

PubMed Central

Pearn, Sophie M; Bennett, Andrew T D; Cuthill, Innes C

2003-01-01

Fluorescence has so far been found in 52 parrot species when illuminated with ultraviolet-A (UVA) 'black' lamps, and two attempts have been made to determine whether such fluorescence plays any role in sexual signalling. However, the contribution of the reflectance versus fluorescence to the total radiance from feathers, even in the most studied species to date (budgerigars), is unclear. Nor has the plumage of this study species been systematically assessed to determine the distribution of fluorescent patches. We therefore used spectrofluorometry to determine which areas of budgerigars fluoresce and the excitation and emission spectra involved; this is the first time that such a technique has been applied to avian plumage. We found that both the yellow crown and (normally hidden) white downy chest feathers exhibit strong UVA-induced fluorescence, with peak emissions at 527 nm and 436 nm, respectively. Conversely, the bright-green chest and dark-blue tail feathers do not fluoresce. When comparing reflectance spectra (400-700 nm) from the yellow crown using illuminants with a proportion of UVA comparable to daylight, and illuminants with all UVA removed, no measurable difference resulting from fluorescence was found. This suggests that under normal daylight the contribution of fluorescence to radiance is probably trivial. Furthermore, these spectra revealed that males had fluorescent crowns with substantially higher reflectance than those of females, in both the UV waveband and at longer wavelengths. Reflectance spectrophotometry was also performed on a number of live wild-type male budgerigars to investigate the chromatic contrast between the different plumage areas. This showed that many plumage regions are highly UV-reflective. Overall our results suggest that rapid surveys using UVA black lamps may overestimate the contribution of fluorescence to plumage coloration, and that any signalling role of fluorescence emissions, at least from the yellow crown of budgerigars, may not be as important as previously thought. PMID:12737665

Different mechanisms of radiation-induced loss of heterozygosity in two human lymphoid cell lines from a single donor

NASA Technical Reports Server (NTRS)

Wiese, C.; Gauny, S. S.; Liu, W. C.; Cherbonnel-Lasserre, C. L.; Kronenberg, A.

2001-01-01

Allelic loss is an important mutational mechanism in human carcinogenesis. Loss of heterozygosity (LOH) at an autosomal locus is one outcome of the repair of DNA double-strand breaks (DSBs) and can occur by deletion or by mitotic recombination. We report that mitotic recombination between homologous chromosomes occurred in human lymphoid cells exposed to densely ionizing radiation. We used cells derived from the same donor that express either normal TP53 (TK6 cells) or homozygous mutant TP53 (WTK1 cells) to assess the influence of TP53 on radiation-induced mutagenesis. Expression of mutant TP53 (Met 237 Ile) was associated with a small increase in mutation frequencies at the hemizygous HPRT (hypoxanthine phosphoribosyl transferase) locus, but the mutation spectra were unaffected at this locus. In contrast, WTK1 cells (mutant TP53) were 30-fold more susceptible than TK6 cells (wild-type TP53) to radiation-induced mutagenesis at the TK1 (thymidine kinase) locus. Gene dosage analysis combined with microsatellite marker analysis showed that the increase in TK1 mutagenesis in WTK1 cells could be attributed, in part, to mitotic recombination. The microsatellite marker analysis over a 64-cM region on chromosome 17q indicated that the recombinational events could initiate at different positions between the TK1 locus and the centromere. Virtually all of the recombinational LOH events extended beyond the TK1 locus to the most telomeric marker. In general, longer LOH tracts were observed in mutants from WTK1 cells than in mutants from TK6 cells. Taken together, the results demonstrate that the incidence of radi-ation-induced mutations is dependent on the genetic background of the cell at risk, on the locus examined, and on the mechanisms for mutation available at the locus of interest.

Discrimination Between Maturity and Composition from Integrated Clementine UltraViolet-Visible and Near-Infrared Data

NASA Astrophysics Data System (ADS)

Le Mouelic, S.; Langevin, Y.; Erard, S.; Pinet, P.; Daydou, Y.; Chevrel, S.

1999-01-01

The Clementine UV-VIS dataset has greatly improved our understanding of the Moon. The UV-VIS camera was limited to five spectral channels from 415 to 1000 nm. The Clementine near-infrared (NIR) camera was designed to complement this spectral coverage. The NIR filter at 2000 run allows the discrimination between olivine and pyroxene within identified mare basalts. In addition, we will show that the integration of Clementine UV-VIS and NIR datasets allows a better evaluation of the ferrous 1-micron absorption band depth and gives access to the slope of the continuum. The discrimination between maturity and FeO composition can be achieved by a principal component analysis performed on spectral parameters. We selected 952 Clementine UV-VIS and NIR images to compute a multispectral cube covering the Aristarchus Plateau. Aristarchus Plateau is one of the most heterogeneous areas on the Moon. Highland-type materials, mare basalts, and dark mantle deposits have previously been mentioned. The mosaic represents a set of about 500 x 600 nine-channel spectra. UV-VIS filters at 415, 750, 900, 950, and 1000 run were calibrated using the ISIS software. We applied the reduction method described elsewhere to reduce the NIR filters at 1100, 1250, 1500 and 2000 nm. Absolute gain and offset values were refined for the NIR images by using eight telescopic spectra acquired as references. With this calibration test, we were able to reproduce the eight telescopic spectra with a maximum error of 1.8%. The integration of UV-VIS and NIR spectral channels allows the visualization of complete low-resolution spectra. In order to investigate the spectral effects of the space-weathering processes, we focused our analysis on a small mare crater and its immediate surroundings. According to the small size of the crater (about 2-km) and its location on an homogeneous mare area, we can reasonably assume that the content in FeO is homogeneous. The impact event has induced a variation of the maturity of the soil by excavating fresh material. Graphs displays five absolute reflectance spectra extracted from this area. One graph displays the same spectra divided by a continuum, which is considered to be a right line fitting the spectra at 0.75 and 1.5 micron. Spectrum 1 is extracted from the brightest part of the crater interior, and spectrum 5 is extracted from the surrounding mare material. Spectra 2, 3, and 4 are extracted from intermediate distances between the two areas. The 1-and-2 micron absorption band depths and the overall reflectance increase from spectrum 5 (corresponding to a mature area) to spectrum 1 (the most immature area). Conversely, the continuum slope decreases from spectrum 5 to spectrum 1. These three spectral effects of maturity have also been identified on laboratory spectra of lunar samples. Most of the lunar soils exhibit a signature near 1 micron. This absorption band is due to the presence of Fe2+ in mafic minerals such as orthopyroxene, clinopyroxene, and olivine. In the case of Clementine UV-VIS data alone, the depth of the 1-micron feature is evaluated by the 950/750-nm reflectance ratio. This ratio combined to the reflectance at 750nm has been used to evaluate the global content in FeO of the lunar surface. Near-infrared data makes a more precise evaluation of the 1 micron band depth possible by providing the right side of the band. The continuum in the vicinity of the band can be evaluated by an arithmetic mean or a geometric interpolation of both sides of the band, which are taken at 750 and 1500nm. The geometric interpolation is less sensitive to residual calibration uncertainties. With this method, the 1-micron absorption band depth for the Aristarchus; Plateau can be refined by as much as 10%. The difference is maximum on Fe-poor, highland-type materials. Similarly, the NIR data provide the possibility to investigate the continuum slope of the spectra. The continuum slope is a key parameter in any spectral analysis. The continuum slope variations seem to be mainly dominated by maturity effects, as suggested by the high correlation with the independent evaluation of maturity (OMAT parameter). We have also found a good correlation between the continuum slope and the OMAT parameter on laboratory spectra of lunar samples of the J. B. Adams collection. The discrimination between maturity effects and composition effects can be achieved by using a principal component analysis (PCA) on three spectral parameters, which are the reflectance at 0.75 micron the depth of the 1-micron feature, and the continuum slope. These parameters are mostly affected by maturity and FeO content. The effects of various glass content are assimilated to maturity. The aim of the PCA is to decorrelate the FeO content and maturity effects in the three input parameters. The integration of UV-VIS and NIR datasets allows for a better understanding of the spectral properties of the lunar surface by giving access to key parameters such as the 1 and 2-micron band depths and the continuum slope. The continuum slope can be combined with the depth of the mafic 1-micron absorption feature and the reflectance at 750 nm to discriminate between maturity and composition. NIR images of the sample return stations will be very interesting to refine absolute FeO content and maturity evaluations. Additional information is available in original.

Variation of optical properties of gel-derived VO2 thin films with temperature

NASA Astrophysics Data System (ADS)

Hou, Lisong; Lu, Song W.; Gan, Fuxi

1991-11-01

VO2 thin films are prepared on three kinds of substrates by the sol-gel dip-coating method followed by heat treatment under vacuum conditions. The IR and UV-visible spectra of the films are studied during heating and cooling between room temperature and 100 degree(s)C. The experimental results show that the films exhibit thermally-induced reversible phase transition and, as a result, the maximum changes in transmittance and reflectivity are 58% and 25%, respectively, in the case of vacuum heat treatment at 400 degree(s)C and silica glass substrates. The refractive index n decreases and the extinction coefficient k increases when heating these films from room temperature to 100 degree(s)C, and vice versa. The reasons why the optical constants and IR absorption spectra change so remarkably are discussed.

Mining the HST "Advanced Spectral Library (ASTRAL) - Hot Stars": The High Definition UV Spectrum of the Ap Star HR 465

NASA Astrophysics Data System (ADS)

Carpenter, Kenneth G.; Ayres, T. R.; Nielsen, K. E.; Kober, G. V.; Wahlgren, G. M.; Adelman, S. J.; Cowley, C. R.

2014-01-01

The "Advanced Spectral Library (ASTRAL) Project: Hot Stars" is a Hubble Space Telescope (HST) Cycle 21 Treasury Program (GO-13346: Ayres PI). It is designed to collect a definitive set of representative, high-resolution ( 30,000-100,000), high signal/noise (S/N>100), and full UV coverage 1200 - 3000 A) spectra of 21 early-type stars, utilizing the high-performance Space Telescope Imaging Spectrograph (STIS). The targets span the range of spectral types between early-O and early-A, including both main sequence and evolved stars, fast and slow rotators, as well as chemically peculiar (CP) and magnetic objects. These extremely high-quality STIS UV echelle spectra will be available from the HST archive and, in post-processed and merged form, at http://casa.colorado.edu ayres/ASTRAL/. The UV "atlases" produced by this program will enable investigations of a broad range of problems -- stellar, interstellar, and beyond -- for many years to come. We offer a first look at one of the earliest datasets to come out of this observing program, a "high definition" UV spectrum of the Ap star HR 465, which was chosen as a prototypical example of an A-type magnetic CP star. HR 465 has a global magnetic field of ~2200 Gauss. Earlier analyses of IUE spectra show strong iron-peak element lines, along with heavy elements such as Ga and Pt, while being deficient in the abundance of some ions of low atomic number, such as carbon. We demonstrate the high quality of the ASTRAL data and present the identification of spectral lines for a number of elements. By comparison of the observed spectra with calculated spectra, we also provide estimates of element abundances, emphasizing heavy elements, and place these measurements in the context of earlier results for this and other Ap stars.

Gamma ray interaction with vanadyl ions in barium metaphosphate glasses; spectroscopic and ESR studies

NASA Astrophysics Data System (ADS)

Abdelghany, A. M.; ElBatal, H. A.; EzzElDin, F. M.

2017-11-01

Optical, FTIR, ESR investigations of prepared undoped barium metaphosphate glass and other samples with the same basic composition containing varying V2O5 contents (0.5, 1, 2, 3%) were carried out before and after gamma irradiation. The undoped glass shows a strong UV optical absorption which is correlated with unavoidable contaminated trace iron impurities. The V2O5-doped samples reveal two additional strong broad visible bands centered at 450 and 680 nm. Such extra peculiar and strong two broad visible bands are related to both tetravalent and trivalent vanadium ions in measurable percent due to the reducing behavior of barium phosphate host glass. Gamma irradiation on the undoped glass results in the generation of collective induced UV and visible bands which are originating from positive hole and electron centers. Glasses containing V2O5 reveal upon gamma irradiation induced defects in the UV as the undoped sample together with distinct splitting within the first broad visible band while the second broad band remains unchanged. This behavior is related to limited photoionization upon the addition of V2O5 indicating specific shielding effect of the vanadium ions towards gamma irradiation. It was noticed that irradiation causes no distinct variations in the FTIR spectra due to the presence of 50% of heavy metal oxide (BaO) and some shielding effect of vanadium ions.

Exploring the DNA damaging potential of chitosan and citrate-reduced gold nanoparticles: Physicochemical approach.

PubMed

Sonia; Komal; Kukreti, Shrikant; Kaushik, Mahima

2018-04-24

Nanomaterials offer a wide range of biomedical applications including gene/drug delivery, biosensing and bioimaging. The cytotoxic and genotoxic potential of nanoparticles need to be thoroughly investigated before their biomedical usage. This study aims to investigate and compare the nanotoxicology of chitosan (CH-Au-Np) and citrate (CI-Au-Np) reduced gold nanoparticles via exploring their interaction with Calf thymus DNA (Ct-DNA) utilizing various physicochemical techniques. Structural characterization of these Nps was done using UV-Visible Spectroscopy and Transmission Electron Microscopy (TEM). Analysis of UV-Visible absorbance spectra indicates that interaction of CH-Au-Np with Ct-DNA causes destabilization of DNA by inducing significant structural and conformational changes in Ct-DNA in a concentration dependent manner, whereas there was negligible interaction between CI-Au-Np and Ct-DNA. These observations were further supported by the results of agarose gel mobility, UV-thermal melting, Circular Dichroism (CD), Dynamic Light Scattering (DLS) and TEM studies. Fluorescence spectral studies using acridine orange (AO) as a fluorescence probe and analysis of thermodynamic parameters reveal that the interactions between Ct-DNA and CH-Au-Np were mainly governed by Van der Waal interactions and Hydrogen bonding. An insightful understanding of genotoxicity induced by CH-Au-Np can be advantageous, as it may provide valuable anticancer approach for cytotoxic drug designing. Copyright © 2018 Elsevier B.V. All rights reserved.

UV-observations with a Brewer spectrophotometer at Hohenpeissenberg

NASA Technical Reports Server (NTRS)

Vandersee, Winfried; Koehler, U.

1994-01-01

Regular spectral UV-B measurements with a Brewer spectrophotometer have been performed at Hohenpeissenberg since 1990. Intercomparison of the Brewer instrument with other UV-B monitoring devices have shown agreement to within plus or minus 10 percent. Comparisons of UV-B spectra measured on fair weather days reveal the well known increasing influence of ozone on UV-B irradiance with decreasing wavelengths. The integral amplification factor the erythemal irradiance reaches values up to 2.8, which can be diminished by increasing turbidity. The influence of cirrus cloud on the UV-B is also shown.

Preparation and characterization of a novel pH-sensitive hydrogel obtained from UV light-induced polymerization

NASA Astrophysics Data System (ADS)

Tian, R. Q.; Zhao, Y. G.; Cui, Y. Q.; Zhang, X. Y.; Zhang, J.; Liang, X. Y.; Shang, Q.

2015-05-01

The main aim of this study was to develop a novel pH-sensitive hydrogel prepared via an UV light-induced polymerization. Single-factor experiments were performed to acquire the optimum formula of final poly(MAA-co-PEGMA) hydrogel. Fourier transform infrared spectroscopy (FTIR) spectra were employed to confirm the successful preparation of the designed copolymers. Inner morphologies of the polymeric hydrogels were observed via an S-4800 scanning electron microscope (SEM). Swelling and reversible swelling-shrinking studies were carried out in different phosphate buffer solution (PBS) with various pH values. Drug-loading tests were performed with bovine serum albumin (BSA) as a model drug. The in vitro release profile was also investigated in PBS with the pH values of 1.2 and 7.4. FTIR spectra confirmed the preparation of the poly(MAA-co-PEGMA) copolymers without any residual monomers. The typical space grid structures were observed from the SEM photographs of hydrogels. The obtained hydrogel showed an excellent pH-sensibility and reversible swelling-shrinking property. The maximum drug-loading (40.9 %) was gained from the BSA concentration of 50.0 mg/mL. During the releasing process, only 5.8 ± 0.9 % of BSA was released at pH 1.2, but 82.1 ± 6.2 % was diffused at pH 7.4. These data suggested that such medicated hydrogel could deliver BSA to alkaline conditions (e.g., intestinal environments) site-specifically, which protected BSA from destroying by gastric acid or pepsase. Therefore, such hydrogel had a significant meaning in theoretical research and practical application.

Ultraviolet observations of clusters of Wolf-Rayet stars in the SBm3 galaxy NGC 4214 and Ultraviolet and optical observations of LINER's

NASA Technical Reports Server (NTRS)

Filippenko, Alexei V.

1992-01-01

The purpose of the grant was to obtain and analyze IUE (UV) and ground-based (optical) spectra of the central bar of NGC 4214, which contains several bright H II regions, in order to further explore the properties of the Wolf-Rayet stars in this galaxy. Several spatially distinct regions, with widely different equivalent widths of optical Wolf-Rayet lines, could be sampled by the large IUE entrance aperture. By using newly developed extraction techniques, the spectra of these H II regions could be isolated, and differences in their stellar populations would be systematically studied. Data were obtained with IUE in late February and early March, 1992. Some of the shifts were successful, but a few were not -- apparently the blind offset from the nearby star did not work equally well in all cases. Thus, the signal-to-noise ratio is somewhat lower than we had hoped. This necessitated a more careful extraction of the spectra of individual H II regions from the two-dimensional spectra. (A program that models the point spread function in the spatial direction was used to deblend the distinct H II regions.) The IUE data are currently being analyzed in conjunction with ground-based optical spectra. There appear to be obvious variations in the stellar population over angular scales of only a few arc seconds. The second part of the research performed under this grant was a continuation of a project that uses IUE (UV) and ground-based (optical) spectra to infer the physical conditions in Low-Ionization Nuclear Emission-Line Regions (LINER's). We have obtained spectra of a few key objects that cover a representative range in LINER continuum and emission-line properties. The overall goals are to (1) separate the emission into spatially distinct components, (2) establish whether the observed nuclear ultraviolet continua indicate sufficient photoionizing fluxes to account for the emission lines, (3) determine whether the nuclear emission can be explained by hot stars alone, (4) detect and measure the strengths of UV emission lines, and (5) search for systematic differences in the UV spectra of LINER's whose other properties differ in some respects.

Near ultraviolet spectroscopic studies of 2,4-diamino-6-piperidinopyrimidine-3-oxide (minoxidil) and 2,4-diamino-6-piperidinopyrimidine (desoxyminoxidil)

NASA Astrophysics Data System (ADS)

Thamann, Thomas J.

The near u.v. spectra of 2,4-diamino-6-piperidinopyrimidine (desoxyminoxidil) and 2,4-diamino-6-piperidinopyrimidine-3-oxide (minoxidil) can be viewed as perturbed pyrimidine spectra. The u.v. properties of pyrimidine and a series of aminopyrimidines, specifically 2,4,6-triaminopyrimidine, are examined to obtain u.v. spectral assignments for desoxyminoxidil and minoxidil. Minoxidil and its desoxy counterpart have C s symmetry, and all π → π* absorptions are allowed 1A' ← 1A' transitions. The two lowest energy π →- π* absorptions observed in minoxidil (262 nm, 292 nm) are tentatively assigned as very mild oxygen → pyrimidine ring charge-transfer transitions. Intensity decreases in protic solvents, and the results of simple Hückel molecular orbital calculations indicate that the 292 nm transition has more charge-transfer character than the 262 nm absorption. The protonated species of desoxyminoxidil and minoxidil have very similar u.v. spectra. This is due to the lack of oxygen-related charge transfer in protonated minoxidil, and the high probability that the positive charge resides in similar environments in the minoxidil and desoxyminoxidil molecular frameworks.

Newer views of the Moon: Comparing spectra from Clementine and the Moon Mineralogy Mapper

USGS Publications Warehouse

Kramer, G.Y.; Besse, S.; Nettles, J.; Combe, J.-P.; Clark, R.N.; Pieters, C.M.; Staid, M.; Malaret, E.; Boardman, J.; Green, R.O.; Head, J.W.; McCord, T.B.

2011-01-01

The Moon Mineralogy Mapper (M3) provided the first global hyperspectral data of the lunar surface in 85 bands from 460 to 2980 nm. The Clementine mission provided the first global multispectral maps the lunar surface in 11 spectral bands across the ultraviolet-visible (UV-VIS) and near-infrared (NIR). In an effort to understand how M3 improves our ability to analyze and interpret lunar data, we compare M3 spectra with those from Clementine's UV-VIS and NIR cameras. The Clementine mission provided the first global multispectral maps the lunar surface in 11 spectral bands across the UV-VIS and NIR. We have found that M3 reflectance values are lower across all wavelengths compared with albedos from both of Clementine's UV-VIS and NIR cameras. M3 spectra show the Moon to be redder, that is, have a steeper continuum slope, than indicated by Clementine. The 1 m absorption band depths may be comparable between the instruments, but Clementine data consistently exhibit shallower 2 m band depths than M 3. Absorption band minimums are difficult to compare due to the significantly different spectral resolutions. Copyright 2011 by the American Geophysical Union.

Newer views of the Moon: Comparing spectra from Clementineand the Moon Mineralogy Mapper

USGS Publications Warehouse

Georgiana Y. Kramer,; Sebastian Besse,; Nettles, Jeff; Jean-Philippe Combe,; Clark, Roger N.; Pieters, Carle M.; Matthew Staid,; Joseph Boardman,; Robert Green,; McCord, Thomas B.; Malaret, Erik; Head, James W.

2011-01-01

The Moon Mineralogy Mapper (M3) provided the first global hyperspectral data of the lunar surface in 85 bands from 460 to 2980 nm. The Clementine mission provided the first global multispectral maps the lunar surface in 11 spectral bands across the ultraviolet-visible (UV-VIS) and near-infrared (NIR). In an effort to understand how M3 improves our ability to analyze and interpret lunar data, we compare M3 spectra with those from Clementine's UV-VIS and NIR cameras. The Clementine mission provided the first global multispectral maps the lunar surface in 11 spectral bands across the UV-VIS and NIR. We have found that M3 reflectance values are lower across all wavelengths compared with albedos from both of Clementine's UV-VIS and NIR cameras. M3 spectra show the Moon to be redder, that is, have a steeper continuum slope, than indicated by Clementine. The 1 μm absorption band depths may be comparable between the instruments, but Clementine data consistently exhibit shallower 2 μm band depths than M3. Absorption band minimums are difficult to compare due to the significantly different spectral resolutions.

Study of interaction between ionic liquids and orange G in aqueous solution with UV-vis spectroscopy and conductivity meter.

PubMed

Zha, Jin-Ping; Zhu, Meng-Ting; Qin, Li; Wang, Xin-Hong

2018-05-05

The interactions between Orange G (OG) with three kinds of ionic liquid surfactants (C 10 mimBF 4 , C 12 mimBF 4 , C 16 mimBF 4 ) and CTAB were studied with UV-Vis spectra and conductivity measurements. The systematic changes in UV-Vis spectra with an increase of carbon-chain length may be observed in presence of OG. They correspond to CMC of every system, respectively, and the CMCs of four systems have exhibit the decrease of CMCs compared to pure surfactant. The binding constants are calculated from the results of conductivity measurements in the order of C 16 mimBF 4 >CTAB>C 12 mimBF 4 >C 10 mimBF 4 . Furthermore, system behaviors presented significant association of complex formation and micelles formation, i.e. the change in UV-Vis spectra before and after the formation of micelles in mixed systems. In addition, Fourier-transform infrared (FT-IR) spectroscopy and 1 H NMR analysis further confirmed that the complexes are formed by hydrogen bond and van der Waal force. These findings could provide scientific guidance for extraction and separation of dyes. Copyright © 2018 Elsevier B.V. All rights reserved.

Study of interaction between ionic liquids and orange G in aqueous solution with UV-vis spectroscopy and conductivity meter

NASA Astrophysics Data System (ADS)

Zha, Jin-Ping; Zhu, Meng-Ting; Qin, Li; Wang, Xin-Hong

2018-05-01

The interactions between Orange G (OG) with three kinds of ionic liquid surfactants (C10mimBF4, C12mimBF4, C16mimBF4) and CTAB were studied with UV-Vis spectra and conductivity measurements. The systematic changes in UV-Vis spectra with an increase of carbon-chain length may be observed in presence of OG. They correspond to CMC of every system, respectively, and the CMCs of four systems have exhibit the decrease of CMCs compared to pure surfactant. The binding constants are calculated from the results of conductivity measurements in the order of C16mimBF4 > CTAB > C12mimBF4 > C10mimBF4. Furthermore, system behaviors presented significant association of complex formation and micelles formation, i.e. the change in UV-Vis spectra before and after the formation of micelles in mixed systems. In addition, Fourier-transform infrared (FT-IR) spectroscopy and 1H NMR analysis further confirmed that the complexes are formed by hydrogen bond and van der Waal force. These findings could provide scientific guidance for extraction and separation of dyes.

The effect of induced strains on photoluminescence properties of ZnO nanostructures grown by thermal evaporation method

NASA Astrophysics Data System (ADS)

Arjmand, Yaser; Eshghi, Hosein

2016-03-01

In this paper, ZnO nanostructures have been synthesized by thermal evaporation process using metallic zinc powder in the presence of oxygen on p-Si (100) at different distances from the boat. The structural and optical characterizations have been carried out. The morphological study shows various shape nanostructures. XRD data indicate that all samples have a polycrystalline wurtzite hexagonal structure in such a way that the closer sample has a preferred orientation along (101) while the ones farther are grown along (002) direction. From the structural and optical data analysis, we found that the induced strains are the main parameter controlling the UV/green peaks ratios in the PL spectra of the studied samples.

UV stabilization of wood by nano metal oxides dispersed in propylene glycol.

PubMed

Nair, Sreeja; Nagarajappa, Giridhar B; Pandey, Krishna K

2018-06-01

Nanoparticles of some of the metal oxides are known to have high UV protective efficiency. The UV filtering efficiency of nanoparticles invariably depends on their size and stability in the dispersion. In the present work, a stable dispersion of nanoparticles of three metal oxides, zinc oxide (ZnO), cerium oxide (CeO 2 ) and titanium dioxide (TiO 2 ), was prepared in propylene glycol (PG) using ultrasonication. The method is easy and useful as no additional surfactant or dispersant is needed. The particle size and its distribution was confirmed by Scanning Electron Microscopy and Dynamic Light Scattering. The stability of dispersion was assessed by UV-visible absorption spectroscopy. The UV stability of wood surfaces of Wrightia tinctoria coated with nanodispersions of ZnO, CeO 2 and TiO 2 was evaluated under laboratory conditions in an accelerated weathering tester. Changes in the colour and FTIR spectra of exposed specimens were measured periodically. Rapid colour darkening (yellowing) was observed in uncoated and PG coated specimens. In contrast, nanodispersion coated specimens prevented photo-yellowing considerably with significant reduction in colour changes examined by CIE L*, a*, b* and ΔE*. Increase in concentration of nanoparticles in the dispersion imparted higher resistance to UV induced degradation. However, increased concentration of nanoparticles reduced the transparency of the coating. FTIR analysis indicated rapid degradation of lignin in uncoated and PG coated specimens due to UV exposure. Coating of wood surfaces with nanodispersions restricted lignin degradation. The study also demonstrates the potential of propylene glycol as a dispersant for developing stable and efficient UV protective nanodispersions for wood coating. Copyright © 2018 Elsevier B.V. All rights reserved.

UV induced visual cues in grasses

PubMed Central

Baby, Sabulal; Johnson, Anil John; Govindan, Balaji; Lukose, Sujith; Gopakumar, Bhaskaran; Koshy, Konnath Chacko

2013-01-01

Grasses are traditionally considered as wind pollinated, however, field observations confirmed frequent insect visits to grass flowers, suggesting insect pollination. Fruit and seed predators inflict heavy losses to cereals and millets during their growth, maturation and storage. The actual factors guiding insects and predators to grass flowers, fruits and seeds are not clear. Here, we report attractive blue fluorescence emissions on grass floral parts such as glumes, lemma, palea, lodicules, staminal filaments, pollens and fruits in ultraviolet (UV) 366 nm, whereas the stigmatic portions were not blue, but red fluorescent. We characterized the blue fluorescent constituent in grass reproductive structures as ferulic acid (FA). Fluorescence spectra of blue-emitting grass floral, seed extracts and isolated FA on excitation at 366 nm showed their emissions at 420–460 nm. We propose these FA-based blue fluorescence emissions in grass reproductive structures as visual cues that attract pollinators, predators and even pests towards them. PMID:24061408

Modified EVA Encapsulant Formulations for Low Temperature Processing: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mei, Z.; Pern, F. J.; Glick, S. H.

2001-10-01

Presented at the 2001 NCPV Program Review Meeting: We have developed several new ethylene-vinyl acetate (EVA) formulations modified on the basis of NREL patented EVA formulations [1]. The new formulations can be cured to a desired gel content of {approx}80% in the ambient at temperatures 20-30 C lower than the typical conditions in vacuum (i.e. {approx}150 C). Glass/glass laminates showed transmittance spectra that are essentially the same as that of EVA 15295P in the visible and NIR regions but higher in the UV region. Results of fluorescence analysis of the ambient-processed new EVA formulations showed the concentrations of the curing-generatedmore » {alpha},{beta}-unsaturated carbonyl chromophores, which are responsible for the UV induced EVA discoloration and photodegradation, were considerably lower than that of EVA 15295P, therefore suggesting a better photochemical stability of new EVA formulations.« less

Investigating the features in differential absorbance spectra of NOM associated with metal ion binding: A comparison of experimental data and TD-DFT calculations for model compounds.

PubMed

Yan, Mingquan; Han, Xuze; Zhang, Chenyang

2017-11-01

In this study, seven model compounds containing typical functional groups (phenolic and carboxylic groups) present in nature organic matter (NOM) were used to ascertain the nature of the characteristic bands in differential absorbance spectra (DAS) of NOM that are induced by metal ion binding. Some similarities were found between the DAS of the examined model compounds, caffeic acid, ferulic acid, sinapic acid, terephthalic acid, isophthalic acid, esculetin and myricetin and those of NOM. The binding of Cu(II) with carboxylic group might produce two peaks, A1 and A2, while the binding of Cu(II) with phenolic group might produce all four Gaussian peaks, from A1 to A4 displayed in the DAS of NOM. The UV-visible spectra predicted using time-dependent density functional theory (TD-DFT)-based methods met well with the experimental DAS of model compounds at different stages of Cu(II) binding. It demonstrates that the features in absorbance spectra are chiefly caused by HOMO (Highest Occupied Molecular Orbital) - LUMO (Lowest Unoccupied Molecular Orbital) transitions in the molecule and that the appearance of peaks in DAS reflects the changes of the molecular orbitals around reactive functional groups in a molecule before and after metal ion binding. The basis of the DAS features of NOM that are induced by metal ion binding could be identified primarily by the frontier molecular orbital theory. Copyright © 2017 Elsevier Ltd. All rights reserved.

Emergence of DNA Polymerase ε Antimutators That Escape Error-Induced Extinction in Yeast

PubMed Central

Williams, Lindsey N.; Herr, Alan J.; Preston, Bradley D.

2013-01-01

DNA polymerases (Pols) ε and δ perform the bulk of yeast leading- and lagging-strand DNA synthesis. Both Pols possess intrinsic proofreading exonucleases that edit errors during polymerization. Rare errors that elude proofreading are extended into duplex DNA and excised by the mismatch repair (MMR) system. Strains that lack Pol proofreading or MMR exhibit a 10- to 100-fold increase in spontaneous mutation rate (mutator phenotype), and inactivation of both Pol δ proofreading (pol3-01) and MMR is lethal due to replication error-induced extinction (EEX). It is unclear whether a similar synthetic lethal relationship exists between defects in Pol ε proofreading (pol2-4) and MMR. Using a plasmid-shuffling strategy in haploid Saccharomyces cerevisiae, we observed synthetic lethality of pol2-4 with alleles that completely abrogate MMR (msh2Δ, mlh1Δ, msh3Δ msh6Δ, or pms1Δ mlh3Δ) but not with partial MMR loss (msh3Δ, msh6Δ, pms1Δ, or mlh3Δ), indicating that high levels of unrepaired Pol ε errors drive extinction. However, variants that escape this error-induced extinction (eex mutants) frequently emerged. Five percent of pol2-4 msh2Δ eex mutants encoded second-site changes in Pol ε that reduced the pol2-4 mutator phenotype between 3- and 23-fold. The remaining eex alleles were extragenic to pol2-4. The locations of antimutator amino-acid changes in Pol ε and their effects on mutation spectra suggest multiple mechanisms of mutator suppression. Our data indicate that unrepaired leading- and lagging-strand polymerase errors drive extinction within a few cell divisions and suggest that there are polymerase-specific pathways of mutator suppression. The prevalence of suppressors extragenic to the Pol ε gene suggests that factors in addition to proofreading and MMR influence leading-strand DNA replication fidelity. PMID:23307893

Merkel Cell Carcinoma.

PubMed

Pulitzer, Melissa

2017-06-01

Merkel cell carcinoma (MCC) encompasses neuroendocrine carcinomas primary to skin and occurs most commonly in association with clonally integrated Merkel cell polyomavirus with related retinoblastoma protein sequestration or in association with UV radiation-induced alterations involving the TP53 gene and mutations, heterozygous deletion, and hypermethylation of the Retinoblastoma gene. Molecular genetic signatures may provide therapeutic guidance. Morphologic features, although patterned, are associated with predictable diagnostic pitfalls, usually resolvable by immunohistochemistry. Therapeutic options for MCC, traditionally limited to surgical intervention and later chemotherapy and radiation, are growing, given promising early results of immunotherapeutic regimens. Copyright © 2017 Elsevier Inc. All rights reserved.

Ectopic recombination between Ty elements in Saccharomyces cerevisiae is not induced by DNA damage.

PubMed

Parket, A; Kupiec, M

1992-10-01

Mitotic recombination is increased when cells are treated with a variety of physical and chemical agents that cause damage to their DNA. We show here, using Saccharomyces cerevisiae strains that carry marked Ty elements, that recombination between members of this family of retrotransposons is not increased by UV irradiation or by treatment with the radiomimetic drug methyl methanesulfonate. Both ectopic recombination and mutation events were elevated by these agents for non-Ty sequences in the same strain. We discuss possible mechanisms that can prevent the induction of recombination between Ty elements.

Thioperoxy derivative generated by UV-induced transformation of N-hydroxypyridine-2(1H)-thione isolated in low-temperature matrixes.

PubMed

Lapinski, Leszek; Gerega, Anna; Sobolewski, Andrzej L; Nowak, Maciej J

2008-01-17

Photochemical transformations of N-hydroxypyridine-2(1H)-thione and its deuterated isotopologue were studied using the matrix-isolation technique. Low-temperature Ar and N2 matrixes containing monomers of this compound were irradiated with continuous-wave near-UV light. Photogeneration of two products was observed in these experiments. The relative population of these photogenerated species was found to be dependent on the wavelength of the UV light used for irradiation. By comparison of the IR spectra of the photoproducts with the spectra simulated theoretically at the DFT(B3LYP)/6-311++G(d, p) level, the final and the intermediate products were identified as rotameric forms of 2-hydroxysulfanyl-pyridine. This is the first report on generation of this thioperoxy derivative of pyridine. The mechanism of photogeneration of 2-hydroxysulfanyl-pyridine involves a photoinduced cleavage of the N-O bond in N-hydroxypyridine-2(1H)-thione, generation of the .OH radical weakly bound with the remaining pyridylthiyl radical, and recombination of these two radicals by formation of the new -S-O- bond. A theoretical model supporting this interpretation was constructed on the basis of approximate coupled cluster (CC2) calculations of the potential energy surfaces of the ground and first excited singlet electronic states of the system. After electronic excitation of the monomeric N-hydroxypyridine-2(1H)-thione, the molecule evolves to the conical intersection with the potential energy surface of the ground state and then to the global minimum corresponding to 2-hydroxysulfanyl-pyridine.

A synthetic peptide blocking TRPV1 activation inhibits UV-induced skin responses.

PubMed

Kang, So Min; Han, Sangbum; Oh, Jang-Hee; Lee, Young Mee; Park, Chi-Hyun; Shin, Chang-Yup; Lee, Dong Hun; Chung, Jin Ho

2017-10-01

Transient receptor potential type 1 (TRPV1) can be activated by ultraviolet (UV) irradiation, and mediates UV-induced matrix metalloproteinase (MMP)-1 and proinflammatory cytokines in keratinocytes. Various chemicals and compounds targeting TRPV1 activation have been developed, but are not in clinical use mostly due to their safety issues. We aimed to develop a novel TRPV1-targeting peptide to inhibit UV-induced responses in human skin. We designed and generated a novel TRPV1 inhibitory peptide (TIP) which mimics the specific site in TRPV1 (aa 701-709: Gln-Arg-Ala-Ile-Thr-Ile-Leu-Asp-Thr, QRAITILDT), Thr 705 , and tested its efficacy of blocking UV-induced responses in HaCaT, mouse, and human skin. TIP effectively inhibited capsaicin-induced calcium influx and TRPV1 activation. Treatment of HaCaT with TIP prevented UV-induced increases of MMP-1 and pro-inflammatory cytokines such as interleukin (IL)-6 and tumor necrosis factor-α. In mouse skin in vivo, TIP inhibited UV-induced skin thickening and prevented UV-induced expression of MMP-13 and MMP-9. Moreover, TIP attenuated UV-induced erythema and the expression of MMP-1, MMP-2, IL-6, and IL-8 in human skin in vivo. The novel synthetic peptide targeting TRPV1 can ameliorate UV-induced skin responses in vitro and in vivo, providing a promising therapeutic approach against UV-induced inflammation and photoaging. Copyright © 2017 Japanese Society for Investigative Dermatology. Published by Elsevier B.V. All rights reserved.

Modifying the Standard Disk Model for the Ultraviolet Spectral Analysis of Disk-dominated Cataclysmic Variables. I. The Novalikes MV Lyrae, BZ Camelopardalis, and V592 Cassiopeiae.

PubMed

Godon, Patrick; Sion, Edward M; Balman, Şölen; Blair, William P

2017-09-01

The standard disk is often inadequate to model disk-dominated cataclysmic variables (CVs) and generates a spectrum that is bluer than the observed UV spectra. X-ray observations of these systems reveal an optically thin boundary layer (BL) expected to appear as an inner hole in the disk. Consequently, we truncate the inner disk. However, instead of removing the inner disk, we impose the no-shear boundary condition at the truncation radius, thereby lowering the disk temperature and generating a spectrum that better fits the UV data. With our modified disk, we analyze the archival UV spectra of three novalikes that cannot be fitted with standard disks. For the VY Scl systems MV Lyr and BZ Cam, we fit a hot inflated white dwarf (WD) with a cold modified disk ( [Formula: see text] ~ a few 10 -9 M ⊙ yr -1 ). For V592 Cas, the slightly modified disk ( [Formula: see text] ~ 6 × 10 -9 M ⊙ yr -1 ) completely dominates the UV. These results are consistent with Swift X-ray observations of these systems, revealing BLs merged with ADAF-like flows and/or hot coronae, where the advection of energy is likely launching an outflow and heating the WD, thereby explaining the high WD temperature in VY Scl systems. This is further supported by the fact that the X-ray hardness ratio increases with the shallowness of the UV slope in a small CV sample we examine. Furthermore, for 105 disk-dominated systems, the International Ultraviolet Explorer spectra UV slope decreases in the same order as the ratio of the X-ray flux to optical/UV flux: from SU UMa's, to U Gem's, Z Cam's, UX UMa's, and VY Scl's.

Simulating the UV Environment For the Synthesis of Prebiotic Molecules

NASA Astrophysics Data System (ADS)

Ranjan, S.; Sasselov, D.

2014-03-01

UV radiation plays a key role in the era of biogenesis. The young Sun was more UV-active than the modern Sun (Ribas et al. 2010), and the Earth lacked an ozone layer, implying a larger UV flux both on Earth, as well as on asteroids/comets. Ultraviolet radiation can help drive prebiotic molecule synthesis (e.g., Chyba et al. 1992; Powner et al. 2009) or destroy biologically important molecules (e.g., Johns et al. 1967). These effects are wavelength dependent: they are sensitive to ionzation, bond, and ro-vibrational transition energies of biologically relevant molecules and their precursors. When simulating the environment at biogenesis it is therefore important to ensure realistic levels of UV input, in both magnitude and spectral shape. Many laboratory simulations of biomolecule synthesis under prebiotic conditions to date have been done with atomic lamps (e.g., Powner et al. 2007). These lamps are safe, stable, and affordable UV sources, well-suited for initial studies. However, their emission spectra are a poor match to prebiotic conditions: low-pressure lamps are characterized by line emission, while higher-pressure lamps do not well-reproduce the spectrum of the young Sun. In this paper, we present spectra that are more realistic approximations to prebiotic conditions. Using published opacity lists and atmospheric models, we compute the attenuation of the flux from a young Sunanalog due to water, and from the present-day Sun due to a planetary atmosphere. We compare these spectra to those emitted by lamps used in studies today, and explore the potential biological implications of the differences. We conclude by discussing possibilities for better simulating the prebiotic UV environment in lab setups.

500 days of SN 2013dy: spectra and photometry from the ultraviolet to the infrared

NASA Astrophysics Data System (ADS)

Pan, Y.-C.; Foley, R. J.; Kromer, M.; Fox, O. D.; Zheng, W.; Challis, P.; Clubb, K. I.; Filippenko, A. V.; Folatelli, G.; Graham, M. L.; Hillebrandt, W.; Kirshner, R. P.; Lee, W. H.; Pakmor, R.; Patat, F.; Phillips, M. M.; Pignata, G.; Röpke, F.; Seitenzahl, I.; Silverman, J. M.; Simon, J. D.; Sternberg, A.; Stritzinger, M. D.; Taubenberger, S.; Vinko, J.; Wheeler, J. C.

2015-10-01

SN 2013dy is a Type Ia supernova (SN Ia) for which we have compiled an extraordinary data set spanning from 0.1 to ˜ 500 d after explosion. We present 10 epochs of ultraviolet (UV) through near-infrared (NIR) spectra with Hubble Space Telescope/Space Telescope Imaging Spectrograph, 47 epochs of optical spectra (15 of them having high resolution), and more than 500 photometric observations in the BVrRiIZYJH bands. SN 2013dy has a broad and slowly declining light curve (Δm15(B) = 0.92 mag), shallow Si II λ 6355 absorption, and a low velocity gradient. We detect strong C II in our earliest spectra, probing unburned progenitor material in the outermost layers of the SN ejecta, but this feature fades within a few days. The UV continuum of SN 2013dy, which is strongly affected by the metal abundance of the progenitor star, suggests that SN 2013dy had a relatively high-metallicity progenitor. Examining one of the largest single set of high-resolution spectra for an SN Ia, we find no evidence of variable absorption from circumstellar material. Combining our UV spectra, NIR photometry, and high-cadence optical photometry, we construct a bolometric light curve, showing that SN 2013dy had a maximum luminosity of 10.0^{+4.8}_{-3.8} × 10^{42} erg s-1. We compare the synthetic light curves and spectra of several models to SN 2013dy, finding that SN 2013dy is in good agreement with a solar-metallicity W7 model.

Jupiter Systems Data Analysis Program Galileo Multi-Spectral Analysis of the Galilean Satellites

NASA Technical Reports Server (NTRS)

Hendrix, Amanda; Carlson, Robert; Smythe, William

2002-01-01

Progress was made on this project at the University of Colorado, particularly concerning analysis of data of the galilean moons Io and Europa. The goal of the Io portion of this study is to incorporate Near Infrared Mapping Spectrometer (NIMS) measured sulfur dioxide (SO2) frost amounts into models used with Ultraviolet spectrometer (UVS) spectra, in order to better constrain SO2 gas amounts determined by the UVS. The overall goal of this portion of the study is to better understand the thickness and distribution of Io's SO2 atmosphere. The goal of the analysis of the Europa data is to better understand the source of the UV absorption feature centered near 280 rim which has been noted in disk-integrated spectra primarily on the trailing hemisphere. The NIMS data indicate asymmetric water ice bands on Europa, particularly over the trailing hemisphere, and especially concentrated in the visibly dark regions associated with chaotic terrain and lines. The UPS data, the first-ever disk-resolved UV spectra of Europa, shown that the UV absorber is likely concentrated in regions where the NIMS data show asymmetric water ice bands. The material that produces both spectral features is likely the same, and we use data from both wavelength regions to better understand this material, and whether it is endogenically or exogenically produced. This work is still in progress at JPL.

Ultraviolet spectra of extreme nearby star-forming regions - approaching a local reference sample for JWST

NASA Astrophysics Data System (ADS)

Senchyna, Peter; Stark, Daniel P.; Vidal-García, Alba; Chevallard, Jacopo; Charlot, Stéphane; Mainali, Ramesh; Jones, Tucker; Wofford, Aida; Feltre, Anna; Gutkin, Julia

2017-12-01

Nearby dwarf galaxies provide a unique laboratory in which to test stellar population models below Z⊙/2. Such tests are particularly important for interpreting the surprising high-ionization ultraviolet (UV) line emission detected at z > 6 in recent years. We present HST/COS UV spectra of 10 nearby metal-poor star-forming galaxies selected to show He II emission in SDSS optical spectra. The targets span nearly a dex in gas-phase oxygen abundance (7.8 < 12 + log O/H < 8.5) and present uniformly large specific star formation rates (sSFR ∼102 Gyr-1). The UV spectra confirm that metal-poor stellar populations can power extreme nebular emission in high-ionization UV lines, reaching C III] equivalent widths comparable to those seen in systems at z ∼ 6-7. Our data reveal a marked transition in UV spectral properties with decreasing metallicity, with systems below 12 + log O/H ≲ 8.0 (Z/Z⊙ ≲ 1/5) presenting minimal stellar wind features and prominent nebular emission in He II and C IV. This is consistent with nearly an order of magnitude increase in ionizing photon production beyond the He+-ionizing edge relative to H-ionizing flux as metallicity decreases below a fifth solar, well in excess of standard stellar population synthesis predictions. Our results suggest that often-neglected sources of energetic radiation such as stripped binary products and very massive O-stars produce a sharper change in the ionizing spectrum with decreasing metallicity than expected. Consequently, nebular emission in C IV and He II powered by these stars may provide useful metallicity constraints in the reionization era.

Solar UV Radiation and the Origin of Life On Earth

NASA Technical Reports Server (NTRS)

Heap, S. R.; Lanz, T.; Hubeny, I.; Gaidos, E.; Oegerle, William R. (Technical Monitor)

2002-01-01

We have embarked on a program aimed at understanding the atmosphere of the early Earth, because of its importance as a greenhouse, radiation shield and energy source for life. Here, we give a progress report on the first phase of this program to establish the UV radiation from the early Sun. We have obtained ultraviolet spectra (STIS, FUSE, EUVE) of carefully selected nearby, young solar-type stars, which act as surrogates for the early Sun We are making detailed non-LTE analyses of the spectra and constructing models of their photospheres + chromospheres. Once validated, these models will allow us to extrapolate our theoretical spectra to other metallicities and to unobserved spectral regions.

Somatic mutation detection in human biomonitoring.

PubMed

Olsen, L S; Nielsen, L R; Nexø, B A; Wassermann, K

1996-06-01

Somatic cell gene mutation arising in vivo may be considered to be a biomarker for genotoxicity. Assays detecting mutations of the haemoglobin and glycophorin A genes in red blood cells and of the hypoxanthine-guanine phosphoribosyltransferase and human leucocyte antigenes in T-lymphocytes are available in humans. This MiniReview describes these assays and their application to studies of individuals exposed to genotoxic agents. Moreover, with the implementation of techniques of molecular biology mutation spectra can now be defined in addition to the quantitation of in vivo mutant frequencies. We describe current screening methods for unknown mutations, including the denaturing gradient gel electrophoresis, single strand conformation polymorphism analysis, heteroduplex analysis, chemical modification techniques and enzymatic cleavage methods. The advantage of mutation detection as a biomarker is that it integrates exposure and sensitivity in one measurement. With the analysis of mutation spectra it may thus be possible to identify the causative genotoxic agent.

In Vivo Function of Tryptophans in the Arabidopsis UV-B Photoreceptor UVR8[W

PubMed Central

O’Hara, Andrew; Jenkins, Gareth I.

2012-01-01

Arabidopsis thaliana UV RESISTANCE LOCUS8 (UVR8) is a photoreceptor specifically for UV-B light that initiates photomorphogenic responses in plants. UV-B exposure causes rapid conversion of UVR8 from dimer to monomer, accumulation in the nucleus, and interaction with CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1), which functions with UVR8 in UV-B responses. Studies in yeast and with purified UVR8 implicate several tryptophan amino acids in UV-B photoreception. However, their roles in UV-B responses in plants, and the functional significance of all 14 UVR8 tryptophans, are not known. Here we report the functions of the UVR8 tryptophans in vivo. Three tryptophans in the β-propeller core are important in maintaining structural stability and function of UVR8. However, mutation of three other core tryptophans and four at the dimeric interface has no apparent effect on function in vivo. Mutation of three tryptophans implicated in UV-B photoreception, W233, W285, and W337, impairs photomorphogenic responses to different extents. W285 is essential for UVR8 function in plants, whereas W233 is important but not essential for function, and W337 has a lesser role. Ala mutants of these tryptophans appear monomeric and constitutively bind COP1 in plants, but their responses indicate that monomer formation and COP1 binding are not sufficient for UVR8 function. PMID:23012433

Skylab

NASA Image and Video Library

1970-01-01

This 1970 photograph shows Skylab's Ultraviolet (UV) Stellar Astronomy experiment, a scientific airlock-based facility/experiment that would study UV spectra of early-type stars and galaxies. The Marshall Space Flight Center had program management responsibility for the development of Skylab hardware and experiments.

UV-B Perception and Acclimation in Chlamydomonas reinhardtii[OPEN

PubMed Central

Chappuis, Richard; Allorent, Guillaume

2016-01-01

Plants perceive UV-B, an intrinsic component of sunlight, via a signaling pathway that is mediated by the photoreceptor UV RESISTANCE LOCUS8 (UVR8) and induces UV-B acclimation. To test whether similar UV-B perception mechanisms exist in the evolutionarily distant green alga Chlamydomonas reinhardtii, we identified Chlamydomonas orthologs of UVR8 and the key signaling factor CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1). Cr-UVR8 shares sequence and structural similarity to Arabidopsis thaliana UVR8, has conserved tryptophan residues for UV-B photoreception, monomerizes upon UV-B exposure, and interacts with Cr-COP1 in a UV-B-dependent manner. Moreover, Cr-UVR8 can interact with At-COP1 and complement the Arabidopsis uvr8 mutant, demonstrating that it is a functional UV-B photoreceptor. Chlamydomonas shows apparent UV-B acclimation in colony survival and photosynthetic efficiency assays. UV-B exposure, at low levels that induce acclimation, led to broad changes in the Chlamydomonas transcriptome, including in genes related to photosynthesis. Impaired UV-B-induced activation in the Cr-COP1 mutant hit1 indicates that UVR8-COP1 signaling induces transcriptome changes in response to UV-B. Also, hit1 mutants are impaired in UV-B acclimation. Chlamydomonas UV-B acclimation preserved the photosystem II core proteins D1 and D2 under UV-B stress, which mitigated UV-B-induced photoinhibition. These findings highlight the early evolution of UVR8 photoreceptor signaling in the green lineage to induce UV-B acclimation and protection. PMID:27020958

The spectroscopic (FTIR, FT-Raman and UV-Vis spectra), DFT and normal coordinate computations of m-nitromethylbenzoate

NASA Astrophysics Data System (ADS)

Gnanasambandan, T.; Gunasekaran, S.; Seshadri, S.

2013-08-01

A combined experimental and theoretical study on molecular structure, vibrational spectra, NBO and UV-spectral analysis of m-nitromethylbenzoate (MNMB) has been reported in the present work. The FT-IR solid phase (4000-400 cm-1) and FT-Raman spectra (3500-100 cm-1) of MNMB was recorded. The molecular geometry, harmonic vibrational frequencies and bonding features of MNMB in the ground-state have been calculated by using the density functional method B3LYP with 6-31G (d,p) and 6-31+G(d,p) basis sets. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the Scaled Quantum Mechanical Force Field Methodology (SQMFF). Stability of the molecule arising from hyperconjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The results show that charge in electron density (ED) in the σ∗ antibonding orbitals and E(2) energies confirms the occurrence of ICT (Intra-molecular Charge Transfer) within the molecule. The UV spectrum was measured in ethyl acetate solution. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) result complements the experimental findings. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Finally the calculation results were applied to simulated infrared and Raman spectra of the title compound which show good agreement with observed spectra.

Photo diagnosis of early pre cancer (LSIL) in genital tissue

NASA Astrophysics Data System (ADS)

Vaitkuviene, A.; Andersen-Engels, S.; Auksorius, E.; Bendsoe, N.; Gavriushin, V.; Gustafsson, U.; Oyama, J.; Palsson, S.; Soto Thompson, M.; Stenram, U.; Svanberg, K.; Viliunas, V.; De Weert, M. J.

2005-11-01

Permanent infections recognized as oncogenic factor. STD is common concomitant diseases in early precancerous genital tract lesions. Simple optical detection of early regressive pre cancer in cervix is the aim of this study. Hereditary immunosupression most likely is risk factor for cervical cancer development. Light induced fluorescence point monitoring fitted to live cervical tissue diagnostics in 42 patients. Human papilloma virus DNR in cervix tested by means of Hybrid Capture II method. Ultraviolet (337 nm) laser excited fluorescence spectra in the live cervical tissue analyzed by Principal Component (PrC) regression method and spectra decomposition method. PCr method best discriminated pathology group "CIN I and inflammation"(AUC=75%) related to fluorescence emission in short wave region. Spectra decomposition method suggested a few possible fluorophores in a long wave region. Ultraviolet (398 nm) light excitation of live cervix proved sharp selective spectra intensity enhancement in region above 600nm for High-grade cervical lesion. Conclusion: PC analysis of UV (337 nm) light excitation fluorescence spectra gives opportunity to obtain local immunity and Low-grade cervical lesion related information. Addition of shorter and longer wavelengths is promising for multi wave LIF point monitoring method progress in cervical pre-cancer diagnostics and utility for cancer prevention especially in developing countries.

Electron holes appear to trigger cancer-implicated mutations

NASA Astrophysics Data System (ADS)

Miller, John; Villagran, Martha

Malignant tumors are caused by mutations, which also affect their subsequent growth and evolution. We use a novel approach, computational DNA hole spectroscopy [M.Y. Suarez-Villagran & J.H. Miller, Sci. Rep. 5, 13571 (2015)], to compute spectra of enhanced hole probability based on actual sequence data. A hole is a mobile site of positive charge created when an electron is removed, for example by radiation or contact with a mutagenic agent. Peaks in the hole spectrum depict sites where holes tend to localize and potentially trigger a base pair mismatch during replication. Our studies of reveal a correlation between hole spectrum peaks and spikes in human mutation frequencies. Importantly, we also find that hole peak positions that do not coincide with large variant frequencies often coincide with cancer-implicated mutations and/or (for coding DNA) encoded conserved amino acids. This enables combining hole spectra with variant data to identify critical base pairs and potential cancer `driver' mutations. Such integration of DNA hole and variance spectra could also prove invaluable for pinpointing critical regions, and sites of driver mutations, in the vast non-protein-coding genome. Supported by the State of Texas through the Texas Ctr. for Superconductivity.

ARMS depletion facilitates UV irradiation induced apoptotic cell death in melanoma.

PubMed

Liao, Yi-Hua; Hsu, Su-Ming; Huang, Pei-Hsin

2007-12-15

Tumor cells often aberrantly reexpress molecules that mediate proper embryonic development for advantageous growth or survival. Here, we report that ankyrin repeat-rich membrane spanning (ARMS), a transmembrane protein abundant in the developing and adult neural tissues, is overexpressed in melanoma, a tumor ontogenetically originating from neural crest. Immunohistochemical study of 79 melanocytic lesions showed significantly increased expression of ARMS in primary malignant melanomas (92.9%) and metastatic melanoma (60.0%) in comparison with benign nevocellular nevi (26.7%). To investigate the role of ARMS in melanoma formation, murine B16F0 melanoma cells with stable knockdown of ARMS were established by RNA interference. Down-regulation of ARMS resulted in significant inhibition of anchorage-independent growth in soft agar and restrictive growth of melanoma in severe combined immunodeficient mice. Importantly, depletion of ARMS facilitated UVB-induced apoptosis in melanoma cells through inactivation of mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK)/ERK. Addition of MEK inhibitor PD98059 further sensitized ARMS-depleted melanoma cells to UVB-induced apoptosis, whereas constitutively active MEK rescued ARMS-depleted cells from apoptosis. We further showed that BRAF, a downstream signaling molecule of ARMS in ERK pathway, is not mutated as a constitutively active form in acral lentiginous melanoma; in contrast, BRAF(T1799A) mutation, which leads to constitutive activation of ERK signaling, was detected in 57.1% of superficial spreading melanoma. Our study suggests that overexpression of ARMS per se serves as one mechanism to promote melanoma formation by preventing stress-induced apoptotic death mediated by the MEK/ERK signaling pathway, especially in acral lentiginous melanoma, most of which does not harbor BRAF mutation.

Single-photon cesium Rydberg excitation spectroscopy using 318.6-nm UV laser and room-temperature vapor cell.

PubMed

Wang, Jieying; Bai, Jiandong; He, Jun; Wang, Junmin

2017-09-18

We demonstrate a single-photon Rydberg excitation spectroscopy of cesium (Cs) atoms in a room-temperature vapor cell. Cs atoms are excited directly from 6S 1/2 ground state to nP 3/2 (n = 70 - 100) Rydberg states with a 318.6 nm ultraviolet (UV) laser, and Rydberg excitation spectra are obtained by transmission enhancement of a probe beam resonant to Cs 6S 1/2 , F = 4 - 6P 3/2 , F' = 5 transition as partial population on F = 4 ground state are transferred to Rydberg state. Analysis reveals that the observed spectra are velocity-selective spectroscopy of Rydberg state, from which the amplitude and linewidth influenced by lasers' Rabi frequency have been investigated. Fitting to energies of Cs nP 3/2 (n = 70 -100) states, the determined quantum defect is 3.56671(42). The demodulated spectra can also be employed as frequency references to stabilize the UV laser frequency to specific Cs Rydberg transition.

The HST/STIS Next Generation Spectral Library

NASA Technical Reports Server (NTRS)

Gregg, M. D.; Silva, D.; Rayner, J.; Worthey, G.; Valdes, F.; Pickles, A.; Rose, J.; Carney, B.; Vacca, W.

2006-01-01

During Cycles 10, 12, and 13, we obtained STIS G230LB, G430L, and G750L spectra of 378 bright stars covering a wide range in abundance, effective temperature, and luminosity. This HST/STIS Next Generation Spectral Library was scheduled to reach its goal of 600 targets by the end of Cycle 13 when STIS came to an untimely end. Even at 2/3 complete, the library significantly improves the sampling of stellar atmosphere parameter space compared to most other spectral libraries by including the near-UV and significant numbers of metal poor and super-solar abundance stars. Numerous calibration challenges have been encountered, some expected, some not; these arise from the use of the E1 aperture location, non-standard wavelength calibration, and, most significantly, the serious contamination of the near-UV spectra by red light. Maximizing the utility of the library depends directly on overcoming or at least minimizing these problems, especially correcting the UV spectra.

The spectra of the chemically peculiar stars

NASA Astrophysics Data System (ADS)

Hack, M.

The spectral properties of the chemically peculiar (CP) stars and the information which is obtainable from them are reviewed. The identification and classification of CP stars in the basis of their spectra is discussed with particular emphasis on the He-rich stars and CNO stars, and recent classification systems based on narrow-band photometry, low-resolution spectrometry or UV spectra are considered. Attention is given to continuum flux distributions, particularly the infrared excesses and UV deficiencies, and the stellar properties (effective temperature and gravity, line blocking, discontinuities, mass and radius) that may be derived from them, and to the magnetic field measurements and evidence for spotted element distributions that may be inferred from spectral surface composition analyses made using LTE model atmospheres are considered which involve both large sample of stars and individual stars, and statistical studies of rotation, magnetic braking and membership in binary systems and clusters are indicated. Finally, UV and X-ray evidence for chromospheres and coronas in some CP stars is noted.