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1.
The short wavelength cut-off (λc), the wavelength of the maximum spectral UV (λMax) of spectral pre-vitamin D3 effective solar UV irradiance (UVD3), and the spectral erythemal UV (UVEry) were compared at 5-min intervals over a 6-month period at solar zenith angles (SZA) ranging from 4.7° to 80°. Averaged over
the entire period, λc for UVD3 is higher by 1.05 nm than that for UVEry. The λMax is higher for UVD3 compared to UVEry for SZA < ~50°. For higher SZA (>55°), the ratio of λMax for UVD3 to that for UVEry is less than 1. As the erythemal action spectrum extends into the UVA, the ratio of UVD3 to UVEry irradiances decreases with increasing SZA, along with a decrease in the ratio of λMax for UVD3 compared to UVEry. The changes in λc and λMax influence both personal UVD3 and UVEry exposure and, to take this into account, a dual calibration technique for polysulphone dosimeters has been developed to simultaneously
provide measurements of both types of exposure. 相似文献
2.
Characterization was performed of a UV-resistant variant strain, UVr-10, derived from a human clonal cell line, RSb, with high sensitivity not only to the lethal effect of 254-nm far-ultraviolet (UV) irradiation but also to the effects of 4-nitroquinoline 1-oxide (4NQO) and N-methyl-N′-nitro-N-nitrosoguanidine (MNNG), and to the cell proliferation inhibition (CPI) effect of human leukocyte interferon (HuIFN-α) preparations.Colony-formation assays confirmed the increased resistance of UVr-10 cells to both UV and 4NQO, but no increased resistance to MNNG. The marked recovery from the inhibition of the total cellular DNA synthesis of UVr-10 cells, estimated by [methyl-3H]thymidine ([3H]dThd) uptake into the cellular DNA materials, was seen during 6 h after irradiation or 4NQO treatment even under the conditions without the recovery uptake into those of the parent RSb cells, but not during 6 h after MNNG treatment. Comparative studies on the activity of DNA repair synthesis between UVr-10 and RSb cells, by measuring the extent of UV-, 4NQO- or MNNG-induced unscheduled DNA synthesis (UDS) and DNA repair replication, revealed an increased activity of UVr-10 cells to UV and 4NQO but no significant increase of the activity to MNNG. These results suggest that increased DNA repair activities of a UVr-10 cell line may account for its becoming resistant to the lethal effect of UV and 4NQO.Concerning the CPI effect of HuIFN-α, UVr-10 cells showed increased resistance. Further, the DNA synthesis activity of UVr-10 cells was not so inhibited by HuIFN-α exposure as that of RSb cells. However, HuIFN-α-exposed UVr-10 cells showed more enhanced levels of activity of pppA(2′p5′A)n synthetase (2–5A synthetase) than the exposed RSb, thus suggesting that HuIFN-α could exert enough intracellular effect even in UVr-10 cells.The implication of the increased resistance of UVr-10 cells to the effects of UV, 4NQO and HuIFN-α, but not to those of MNNG, is discussed. 相似文献
3.
Using synchronous populations obtained by selectively detaching mitotic cells from cultures grown in monolayer, we demonstrate here that Chinese hamster ovary (CHO) cells exhibit a differential sensitivity to mutation induction by UV as a function of position in the cell cycle. When mutation induction to 6-thioguanine (TG) resistance is monitored, several maxima and minima are displayed during cell-cycle traverse, with a major maximum occurring in early S phase. Although cells in S phase are more sensitive to UV-mediated cell lethality than those in G1 or G2/M phases, there is not a strict correlation with induced mutation frequency. Fluence-response curves obtained at several times during the cell cycle yield Dq values approximating 6 J/m2. The primary survival characteristic which varies with cell cycle position is D0, ranging from 2.5 J/m2 at 6 h after mitotic selection to 5.5 J/m2 at 11 h afterward. Based on studies with asynchronous, logarithmically growing populations, as well as those mitotically selected to be synchronous, the optimum phenotypic expression time for induced TG resistance is 7–9 days and is essentially independent of both UV fluence and position in the cell cycle. All isolated mutants have altered hypozanthine—guanine phosphoribosyl transferase (HGPRT) activity, and no difference in the residual level of activity was detected among isolated clones receiving UV radiation during G1, S, or late S/G2 phases of the cell cycle. Changes in cellular morphology during cell-cycle traverse do not contribute to the differential susceptibility to UV-induced mutagenesis. 相似文献
4.
Vanessa Moura dos Santos Soares Hyago Keslley de Lucena Soares Suellen da Silva Santos Reinaldo Farias Paiva de Lucena 《Journal of ethnobiology and ethnomedicine》2018,14(1):77
Background
The use of wild birds, for several purposes, is directly associated with cultural, ecological, and conservation issues. This study aimed to inventory the wild birds known and used in three communities in Paraíba state, northeast Brazil, and to investigate the sociocultural context in which these activities occur.Methods
A total of 179 people (98 women and 81 men) were interviewed. Data were collected through free interviews, using semi-structured forms, and posing questions about the use of local wild birds. The species were identified by direct observation of the birds, analysis of photographic records, and the use of a scientific guide.Results
Each species’ use value (UV) was calculated in three different ways: UVgeneral, UVcurrent, and UVpotential. These UVs ranged from 0.01 to 1.15 for UVg, 0 to 0.21 for UVc, and 0.01 to 1.02 for UVp. A total of 99 species, 81 genera, and 40 families were recorded and classified into the use categories of food, breeding, and medicinal. Thraupidae (12 species), Columbidae, Accipitridae, and Icteridae (8 species each) were the most diverse families.Conclusions
The use of wild birds is a widespread activity in the studied areas, where many species are used. This demonstrates the need to conduct studies to assess the pressure suffered by these bird species, as well as the need to create public policies that intervene in the use and conservation of wild birds.5.
Three UV sensitive (UVs) mutants (CHO43RO, CHO423PV, CHO30PV), characterized by different levels of reduction in their ability to perform unscheduled DNA synthesis (UDS), were analysed for spontaneous and UV-induced frequency of chromosomal aberrations and for sensitivity to alkylating agents. The baseline frequency of chromosomal aberrations was in the normal range, whereas after UV irradiation a positive correlation between the degree of UV sensitivity and the rate of chromosomal breakage was observed. Survival experiments after mutagen exposure indicated that the UVs clones are characterized by different levels of hypersensitivity to bifunctional alkylating agents whereas the sensitivity to monofunctional alkylating agents is in the normal range. Genetic analysis performed by measuring the survival after UV in hybrids produced by fusing UVs cells with wild-type or UVs cells belonging to the six Chinese hamster complementation groups, indicated that the three clones carry recessive mutations and belong to c.g. 2. These findings suggest that defects in the same gene may result in different degrees of phenotypic alterations.Abbreviations CG
complementation group
- EMS
ethyl methane sulfonate
- MMS
methyl methane sulfonate
- MMC
mitomycin C
- UV
ultraviolet
- UDS
unscheduled DNA synthesis 相似文献
6.
Finn B. Haugli William F. Dove Antonio Jimenez 《Molecular & general genetics : MGG》1972,118(2):97-107
Summary Cycloheximide-resistant mutants of Physarum polycephalum were induced in the haploid myxamoebae by the combined action of UV1 and caffeine (Haugli and Dove, 1972) or by treatment with NMG2. Eight independent mutants segregated in a Mendelian fashion (Table 1). Crosses between 6 of the mutants revealed 2 loci, actA and actB, for cycloheximide resistance (Table 2).All mutants are expressed in the plasmodium and are recessive in heterozygotes (Fig. 1 and 2). One mutation, conferring resistance to high levels of cycloheximide, was studied in heterokaryons and found to be incompletely recessive.An in vitro peptide synthesizing system was constructed from ribosomes from Physarum and supernatant factors from Saccharomyces cerevisiae. Cycloheximide strongly inhibited the activity of ribosomes derived from either wild type or mutants at the actB locus. In contrast, ribosomes from mutants at the actA locus were resistant to cycloheximide. Thus, the actA locus operates through the ribosomes. 相似文献
7.
Deoxyribonucleic Acid Synthesis in Ultraviolet-Light-Irradiated Chinese Hamster Cells 总被引:2,自引:0,他引:2
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Two mammalian cell lines, Chinese hamster ovary (CHO) which can recover colony-forming ability between fractionated doses of ultraviolet light (UV), and Chinese hamster B-14FAF28 which cannot recover, were tested for the ability to bypass UV-induced photoproducts in DNA during postirradiation DNA synthesis. The molecular weight distributions of newly synthesized DNA in UV-irradiated populations of both cell lines showed evidence for photoproduct bypass. Hence, the bypass mechanism does not correlate with recovery after UV. 相似文献
8.
Background: FTIR spectroscopy is classically used to study the supramolecular organization of the stratum corneum lipids. Exposure to UVA is responsible for a small decrease in packing observed on cutaneous lipid films. Methods: Lipid films and human skin biopsies were either exposed to UVA irradiation of 120 J/cm2, UVB irradiation of 0.15 J/cm2 or put in contact with ethanol. Using FTIR in vitro and IR microspectroscopy ex vivo provided information on: i) the precise localisation of the stratum corneum in the skin, ii) its thickness, and iii) the organization of its constituted lipids. Results: Different action modes were observed for UV irradiation and the contact with ethanol with a certain destabilisation of the lipidic layer. Ethanol was also found to be responsible for the creation of pores. The destabilisation of the lipid cement was mainly observed ex vivo. Conclusion: The barrier function of the skin is affected by the action of physical and chemical external agents at the molecular level. The increased laxity of the lipid packing could enable the percutaneous penetration velocity of actives. 相似文献
9.
以中波紫外线为主的紫外辐射对人体健康具有多种生物学影响,城市森林能够为居民提供温和的紫外辐射环境。为了解林下紫外线辐射环境特征是否存在树种间差异,对北京市3种常见遮荫树种的夏季林下紫外辐射(UV)强度、林内与林外UV辐射的比值(SR)、UV-B在总UV辐射中占比(UV-B/UV),以及VD合成和红斑效应两种人体作用有效辐射强度(UVVD、UVer)进行了测算。结果表明:(1)三种林分林内紫外辐射总量是林外的3%—10%,不同林分的林内UV强度具有显著差异,元宝枫林对UV屏蔽能力最强,其次是栾树林和国槐林;(2)三种林分林冠对不同波长上紫外辐射能量的屏蔽能力具有明显的一致性,林冠对UV-B的屏蔽能力没有在UVA波段强和稳定,林内UV-B/UV普遍高于林外,其中元宝枫林最高,其次为栾树林,国槐林最低;(3)林冠明显改变了日光UVVD和UVer两种人体作用光谱曲线的形态,三种林分内的人体作用光谱曲线形态相似,强度上,林内外UVVD/UVer值均接近1,不同林分间... 相似文献
10.
Jeff Reeve Lorraine H. Kligman Robert Anderson 《Applied microbiology and biotechnology》1990,33(2):161-166
Summary Isolated lipids from Deinococcus radiodurans were reconstituted at final concentrations of 1 mg/ml into dioleoyl phosphatidyl choline (DOPC) vesicles and assayed for the ability to protect cells of Escherichia coli against killing by UV light (254 nm). Values of D37 (UV dose required to reduce the number of surviving cells to 37% of the original number) were calculated from killing curves. E. coli was afforded the greatest protection with an individual lipid, identified as vitamin MK8 (D37=310 J//m2, compared to D37=67 J/m2 for E. coli irradiated in the presence of DOPC alone). Liposome-mediated protection was dependent on UV254 absorbance and not on turbidity-related light-scattering. BOth vitamin MK8 from D. radiodurans and vitamin K1, which is available commercially, showed a similar degree of UV254-protection for E. coli. The UV-protective properties of vitamin K1 were also investigated on mammalian cells in comparison with other natural lipids and known sunscreens. Survival curves were obtained for mouse fibroblast (L) cells irradiated at UV254 in the absence or presence of DOPC liposomes into which were incorporated various natural lipids or standard sunscreen ingredients, all at final concentrations of 1 mg/ml. Experimentally determined values of D37 were as follows: Vitamin K1, 73 J/m2; \-carotene, 44 J/m2; -tocopherol, 20 J/m2; sulisobenzone, 156 J/m2; p-aminobenzoic acid (PABA), 113 J/m2; benzophenone, 80 J/m2; oxybenzone, 61 J/m2 and DOPC alone. 23 J/m2. Vitamin K1, the most protective lipid tested, was also compared with PABA and oxybenzone (all at concentrations of 20 mg/ml; applied topicall) for its ability to protec Skh-hairless mice from UV254-induced erythema, yielding a UV254 protection factor of 3.5. In addition, vitamin K1 (at 100 mg/ml) was able to provide hairless mice with a small degree of UVB protection, as indicated by an experimentally determined Solar Protection Factor of 1.5–2.0. Although it is concluded that vitamin K is not likely to account for the extraordinarily high degree of UV-resistance of D. radiodurans, vitamin K does show characteristics worthy of its consideration as a UV-screening agent.
Offprint requests to: R. Anderson 相似文献
11.
Variation In G1 Transit Time Relative to the Cycloheximide and Actinomycin D Drug Restriction Points
The transit time distribution at various points in the cell cycle of synchronized Chinese hamster ovary cells was determined from the mitotic index, [3H]thymidine labeling index and increase in cell number monitored at regular intervals after mitotic selection. Variation in G1 transit time compared with that for the total cell cycle indicates that variation in cell cycle transit time occurs mainly during G1 phase. the cycloheximide (5.0 μg/ml) and actinomycin D (3.0 μg/ml) restriction points occur 0.2 and 1.7 hr prior to entry into S phase, respectively. the transit time distributions are further characterized by the moments of the distributions. the variance (2nd moment about the mean) of the transit time distribution at the actinomycin D restriction point is similar to the variance of the transit time distribution at the G1/S border, thus variation in cell cycle transit time originates earlier than 1.7 hr prior to entry into S phase (i.e., the first 3/4 of G1). If G1 transit time variability and cell cycle control are related, then the results presented here indicate that the major regulatory events do not occur during late G1 phase. 相似文献
12.
Induction of forward mutations in mutationally defective yeast 总被引:5,自引:0,他引:5
Jeffrey F. Lemontt 《Molecular & general genetics : MGG》1972,119(1):27-42
Summary The 3 rev loci that reduce ultraviolet light (UV)-induced reversion in S. cerevisiae had a similar effect on forward mutation to auxotrophy induced by a single 400 erg/mm2 UV dose: rev1-1, rev2-1 and rev3-1 reduced average frequencies of auxotrophs to 4%, 64% and 4% that in wild type and reduced frequencies of mutants at ade1 or ade2 to 19%, 88% and 2% wild type, respectively. The rev2-1 strain exhibited high frequencies of spontaneous mutation. It is suggested that rev1-1 and rev3-1 block steps in a general UV mutation mechanism controlling forward and reverse mutation throughout the genome. The small effect of rev2-1, compared to the effect of rev1-1 or rev3-1, is consistent with previously obtained data on UV reversion and could be due to a specificity for induced mutation involving only certain types of UV damage or, on the other hand, it may be related to mutator activity. Although rev caused varying degrees of sensitivity to ethylmethanesulfonate (EMS), there was little or no significant effect on mutation induced by a single 30 min. dose of 3% EMS. Auxotroph frequencies were 79%, 109% and 94% wild type, whild frequencies at ade1 or ade2 were 82%, 56% and 51% wild type in the respective strains. It is suggested that steps blocked by rev, although they may participate in repair of lethal EMS damage, do not themselves generate EMS-induced mutations. 相似文献
13.
Dose-response curves for “mutation” to resistance to 5-iodo-2-deoxyuridine (IUdR) and excess thymidine (TdR) in P388 mouse lymphoma cells have been established after exposure of these cells to six chemical mutagens, UV |and| ionising radiations. The dose-response curves for all mutagens in both selective system show considerable similarities when induced mutation frequencies are plotted against survival. Expression time for both types of variants, IUdRr and TdRr, are similar, i.e. maximum frequencies are reached by 48 h and there is no fall in variant frequency at late expression times up to 144 h. Over the range of survival levels studied there appears to be little or no dependence of expression time on dose of mutagen. Some loss of mutants after high doses (i.e. at low survival levels) was observed due to the fact that a significant proportion of both TdRr and IUdRr clones were more sensitive to the mutagens than the wild-type population. The similarities in induced dose-response curves for different mutagens suggest that the mutants have a common origin, probably an error in repair, but it seems unlikely that errors in “cut and patch” repair are responsible. A comparison of spontaneous frequencies of IUdRr and TdRr variants suggests that IUdR is mutagenic in P388 cells. 相似文献
14.
Masami Watanabe 《Mutation research》1980,71(2):219-231
8-Azaguanine (8AG)-resistant mutations induced by X-rays, ultraviolet radiation (UV) and a chemical carcinogen, 4-hydroxyaminoquinoline 1-oxide (4-HAQO) were examined during the cell cycle of synchronized HeLa S3 cells. Mutants induced by 400 R of X-rays occurred in a higher frequency in the X-ray sensitive G1-S boundary phase than in the X-ray-resistant G2, S and early g2 phases. 8AG-resistant mutants induced by treatment with 10?5 M 4-HAQO for 20 min appeared in a higher frequency in the early to middle S phases than in the other phases. In the case of UV, however, we found no significant difference in the induced mutation frequencies the cell cyle, because the mutation frequencies induced by the UV doses (0–20 Jm2) used were too low for detection of the difference. These results suggest that there is a close correlation between the critical damage induced in DNA molecule(s) at the DNA-synthetic phase in the cell cycle and mutagenesis, because mitotic cells have a low mutability in spite of their high radio-sensitivity. 相似文献
15.
Summary A Monte Carlo simulation is proposed to study the dynamics of helper T-cells (N
H) and viral (N
V) populations in an immune response model relevant to HIV. Cellular states are binary variables and the interactions are described
by logical expressions. Viral population shows a nonmonotonic growth before reaching a constant value while helper T-cells
grow to a constant after a relaxation/reaction time. Initially, the population of helper cells grows with time with a power-law,
N
H ∼t
β, before reaching the steady-state; the growth exponent β increases systematically (β ≈ 1 – 2) with the mutation rate (P
mut≈0.1–0.4). The critical recovery time (t
c) increases exponentially with the viral mutation, t
c≈Ae
αP
mut
, with α=4.52±0.29 in low mutation regime and α=15.21±1.41 in high mutation regime. The equilibrium population of helper T-cell
declines slowly with P
mut and collapses at ∼ 0.40; the viral population exhibits a reverse trend, i.e., a slow increase before the burst around the
same mutation regime. 相似文献
16.
Rapid modulation of ultraviolet shielding in plants is influenced by solar ultraviolet radiation and linked to alterations in flavonoids
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Paul W. Barnes Mark A. Tobler Ken Keefover‐Ring Stephan D. Flint Anne E. Barkley Ronald J. Ryel Richard L. Lindroth 《Plant, cell & environment》2016,39(1):222-230
The accumulation of ultraviolet (UV)‐absorbing compounds (flavonoids and related phenylpropanoids) and the resultant decrease in epidermal UV transmittance (TUV) are primary protective mechanisms employed by plants against potentially damaging solar UV radiation and are critical components of the overall acclimation response of plants to changing solar UV environments. Whether plants can adjust this UV sunscreen protection in response to rapid changes in UV, as occurs on a diurnal basis, is largely unexplored. Here, we use a combination of approaches to demonstrate that plants can modulate their UV‐screening properties within minutes to hours, and these changes are driven, in part, by UV radiation. For the cultivated species Abelmoschus esculentus, large (30–50%) and reversible changes in TUV occurred on a diurnal basis, and these adjustments were associated with changes in the concentrations of whole‐leaf UV‐absorbing compounds and several quercetin glycosides. Similar results were found for two other species (Vicia faba and Solanum lycopersicum), but no such changes were detected in Zea mays. These findings reveal a much more dynamic UV‐protection mechanism than previously recognized, raise important questions concerning the costs and benefits of UV‐protection strategies in plants and have practical implications for employing UV to enhance crop vigor and quality in controlled environments. 相似文献
17.
We have determined the ability of UV254nm-irradiated murine lymphoma cells to adapt their NAD+ metabolism to the increased NAD+ consumption for the poly ADP-ribosylation of chromatin proteins. Two murine lymphoma sublines with differential UV-sensitivity
and poly(ADP-ribose) turnover were used as a model system. The first subline, designated LY-R is UV254nm-sensitive and tumorigenic in DBA/2 mice. The second subline, LY-S is UV254nm-resistant and nontumorigenic. Following treatment of these cells with 2 mM benzamide, an inhibitor of the NAD+-utilizing enzyme poly(ADP-ribose) polymerase, NAD+ levels slowly increased up to about 160% of control levels after 3 hours. When benzamide was added to these cultures 20 min
after UV254nm irradiation, a dramatic transient increase of NAD+ levels was observed within 4 min in LY-R cells and more moderately in LY-S cells. At later times after UV254nm irradiation, the NAD+ levels increased in both sublines reaching up to 200% of the concentrations prior to benzamide treatment. These results demonstrate
an adaptative response of NAD+ metabolism to UV254nm irradiation. In parallel, we observed a differential repartitioning of ADP-ribosyl residues between the NAD+ and poly(ADP-ribose) pools of LY-R and LY-S cells that correlates with the differential UV sensitivity of these cells. 相似文献
18.
Carol Bernstein Don Morgan Helen L. Gensler Silke Schneider George E. Holmes 《Molecular & general genetics : MGG》1976,148(2):213-220
Summary A temperature sensitive ligase allele of phage T4 reduced or eliminated HNO2 induced reversion of am mutants. Since at the temperatures used, the ligase mutant is defective in the repair of some types of lethal lesions (i.e., UV, MMS and EMS induced lesions) these results indicate that HNO2 mutagenesis may occur through a ligase dependent repair pathway. In contrast, 2AP induced mutation was not inhibited by mutants defective in the gene 30 ligase or in genes 32, 39, 41, 44, 45, 46, 47, 49, 52, 56, 58–61 and v. This indicates that 2AP mutagenesis probably does not depend on a repair pathway in phage T4. 相似文献
19.
Survival of adult Daphnia magna was assessed after acute (<96h) exposure to UV312 under various temperatures (6, 12 and 18°C)or oxygen concentrations (5.6, 8.5 and 14.1 mg O2 l1)in the laboratory. The surviving animals were screened for theenzymes catalase (CAT) and glutathione transferase (GST), whichmay protect against UV-induced oxidative damage. In addition,the same two enzymes were assayed in separate experiments afteracute exposure to UV312 (6 h, 0.014 mW cm2) and the differentlevels of temperature and oxygen. No differences were observedin either CAT or GST activity after exposure to the three levelsof oxygen, but there was a tendency for decreasing specificactivity with decreasing temperature for both enzymes. CAT activitywas not influenced by UV radiation, whereas GST activity displayeda slight increase. Oxygen concentration did not influence survivalduring UV exposure but, contrary to expectations, survival testsat different temperatures clearly showed that reduced temperatureincreased survival. The results indicate that temperature effectsmust be considered when comparing dose effect relationshipsin situ, and suggest that low temperature is not a major causeof UV susceptibility in cold-adapted alpine and Arctic populationsof Daphnia. 相似文献
20.
M Zernik-Kobak M Pirsel J Doniger J A DiPaolo A S Levine K Dixon 《Mutation research》1990,242(1):57-65
We have constructed a series of polyomavirus-based shuttle vectors for analyzing mechanisms of mutagenesis in rodent cell systems. These vectors contain the supF suppressor tRNA gene which serves as the mutagenesis target; the pBR327 replication functions and ampr gene for replication and selection in bacteria; and the polyomavirus genome which permits replication in rodent cells. The polyoma genomes used in these vectors vary in their enhancer regions, causing varying efficiencies of replication in different types of rodent cells. One of the vectors (pPySLPT-2) which replicates particularly well in several different rodent cell types (i.e., Chinese hamster ovary, mouse hepatoma and mouse lymphoma) was used to compare mutation induction by UV radiation in UV repair-deficient mouse lymphoma L5178Y-R cells with mutagenesis in the related UV repair-proficient line, L5178Y-S. In both cell types, UV-induced mutants could be recovered at frequencies up to 50-fold higher than that of the spontaneous background. At a given UV fluence the L5178Y-R cells were more highly mutable than the L5178Y-S cells. Our results indicate that these new polyomavirus-based vectors should be useful for analysis of the molecular mechanisms of mutation induction in rodent cell systems, and in particular should allow detailed analysis of mutagenesis in the well characterized rodent somatic cell mutants. 相似文献