Photochemistry and Photobiology

Cover image for Vol. 91 Issue 1

Edited By: Jean Cadet

Impact Factor: 2.684

ISI Journal Citation Reports © Ranking: 2013: 36/74 (Biophysics); 161/291 (Biochemistry & Molecular Biology)

Online ISSN: 1751-1097

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  • INVITED REVIEW: UV Signature Mutations

    INVITED REVIEW: UV Signature Mutations

    Sequencing complete tumor genomes and exomes has sparked the cancer field's interest in mutation signatures for identifying the tumor's carcinogen. This review and meta-analysis discusses signatures and their proper use. We first distinguish between a mutagen's canonical mutations—deviations from a random distribution of base changes to create a pattern typical of that mutagen—and the subset of signature mutations, which are unique to that mutagen and permit inference backward from mutations to mutagen. To verify UV signature mutations, we assembled literature datasets on cells exposed to UVC, UVB, UVA, or solar simulator light (SSL) and tested canonical UV mutation features as criteria for clustering datasets. A confirmed UV signature was: ≥60% of mutations are CT at a dipyrimidine site, with ≥5% CCTT. Other canonical features such as a bias for mutations on the nontranscribed strand or at the 3′ pyrimidine had limited application. The most robust classifier combined these features with criteria for the rarity of non-UV canonical mutations. In addition, several signatures proposed for specific UV wavelengths were limited to specific genes or species; UV's nonsignature mutations may cause melanoma BRAF mutations; and the mutagen for sunlight-related skin neoplasms may vary between continents.

  • INVITED REVIEW: Oculocutaneous Albinism in Sub-Saharan Africa: Adverse Sun-Associated Health Effects and Photoprotection

    INVITED REVIEW: Oculocutaneous Albinism in Sub-Saharan Africa: Adverse Sun-Associated Health Effects and Photoprotection

    Oculocutaneous albinism (OCA) is a genetically inherited autosomal recessive condition. Individuals with OCA lack melanin and therefore are susceptible to the harmful effects of solar ultraviolet radiation, including extreme sun sensitivity, photophobia and skin cancer. OCA is a grave public health issue in sub-Saharan Africa with a prevalence as high as 1 in 1000 in some tribes. This article considers the characteristics and prevalence of OCA in sub-Saharan African countries. Sun-induced adverse health effects in the skin and eyes of OCA individuals are reviewed. Sun exposure behavior and the use of photoprotection for the skin and eyes are discussed to highlight the major challenges experienced by these at-risk individuals and how these might be best resolved.

  • RESEARCH ARTICLE: Simultaneous Irradiation with Different Wavelengths of Ultraviolet Light has Synergistic Bactericidal Effect on Vibrio parahaemolyticus

    RESEARCH ARTICLE: Simultaneous Irradiation with Different Wavelengths of Ultraviolet Light has Synergistic Bactericidal Effect on Vibrio parahaemolyticus

    Ultraviolet (UV) irradiation is an increasingly used method of water disinfection. UV rays can be classified by wavelength into UVA (320–400 nm), UVB (280-320 nm), and UVC (<280 nm). We previously developed UVA sterilization equipment with a UVA light-emitting diode (LED). The aim of this study was to establish a new water disinfection procedure using the combined irradiation of the UVA-LED and another UV wavelength. An oxidative DNA product, 8-hydroxy-2’-deoxyguanosine (8-OHdG), increased after irradiation by UVA-LED alone, and the level of cyclobutane pyrimidine dimers (CPDs) was increased by UVC alone in Vibrio parahaemolyticus. Although sequential irradiation of UVA-LED and UVC-induced additional bactericidal effects, simultaneous irradiation with UVA-LED and UVC-induced bactericidal synergistic effects. The 8-OHdG and CPDs production showed no differences between sequential and simultaneous irradiation. Interestingly, the recovery of CPDs was delayed by simultaneous irradiation. The synergistic effect was absent in SOS response-deficient mutants, such as the recA and lexA strains. Because recA- and lexA-mediated SOS responses have crucial roles in a DNA repair pathway, the synergistic bactericidal effect produced by the simultaneous irradiation could depend on the suppression of the CPDs repair. The simultaneous irradiation of UVA-LED and UVC is a candidate new procedure for effective water disinfection.

  • RESEARCH ARTICLE:Sun protection Provided by Regulation School Uniforms in Australian Schools: An Opportunity to Improve Personal Sun protection During Childhood

    RESEARCH ARTICLE:Sun protection Provided by Regulation School Uniforms in Australian Schools: An Opportunity to Improve Personal Sun protection During Childhood

    Childhood sun exposure is linked to excessive pigmented mole development and melanoma risk. Clothing provides a physical barrier, protecting skin from ultraviolet radiation (UVR). Extending sleeves to elbow length and shorts to knee length has been shown to significantly reduce mole acquisition in preschoolers from tropical Queensland. We used publicly available uniform images and guidelines from primary schools in Townsville (latitude 19.25°S, n = 43 schools), Cairns (16.87°S, n = 46) and the Atherton Tablelands (17.26°S, n = 23) in tropical Australia to objectively determine the body surface proportion covered by regulation school uniforms. Uniforms of nongovernment, large (≥800 students), urban, educationally advantaged schools with comprehensive sun protection policies covered more skin than those of government schools (63.2% vs 62.0%; P < 0.001), smaller schools (63.4% vs 62.3%; P = 0.009), rural (62.7% vs 61.9%; P = 0.002) and educationally disadvantaged schools (62.8% vs 62.3%; P < 0.001) with underdeveloped sun protection policies (62.8% vs 62.2%; P = 0.002). Overall, SunSmart and non-SunSmart school uniforms covered identical body surface proportions (62.4%, P = 0.084). Although wearing regulation school uniforms is mandatory at most Australian primary schools, this opportunity to improve children's sun protection is largely overlooked. Recent evidence suggests that even encouraging minor alterations to school uniforms (e.g. slightly longer sleeves/dresses/skirts/shorts) to increase skin coverage may reduce mole acquisition and melanoma risk, especially in high-risk populations.

  • RESEARCH ARTICLE: The Employment of a Removable Chitosan-Derivatized Polymeric Sensitizer in the Photooxidation of Polyhydroxylated Water-Pollutants

    RESEARCH ARTICLE: The Employment of a Removable Chitosan-Derivatized Polymeric Sensitizer in the Photooxidation of Polyhydroxylated Water-Pollutants

    The known O2(1∆g)-sensitizer system Chitosan bounded Rose Bengal (CH-RB), with Rose Bengal (RB) immobilized by irreversible covalent bonding to the polymer Chitosan (CH), soluble in aquous acidic medium, was employed in the photodegradation of three tri-hydroxy benzene water-contaminants (THBs). The system sensitizes the O2(1∆g)-mediated photodegradation of THBs by a process kinetically favored, as compared to that employing free RB dissolved in the same solvent. Additionally the free xanthene dye, degradable by O2(1∆g) through self-sensitization upon prolonged light-exposure, is considerably protected when bonded to CH-polymer. The polymeric sensitizer, totally insoluble in neutral medium, can be removed from the solution after the photodegradative cycle by precipitation through a simple pH change. This fact constitutes an interesting aspect in the context of photoremediation of confined polluted waters. In other words, the sensitizing system could be useful for avoiding to dissolve dyestuffs in the polluted waters, in order to act as conventional sunlight-absorbing dye-sensitizers. In parallel the interaction CH - O2(1∆g) in acidic solution was evaluated. The polymer quenches the oxidative species with a rate constant 2.4 × 108 M−1 s−1 being the process mostly attributable to a physical interaction. This fact promotes the photoprotection of the bonded dye in the CH-RB polymer.

  • INVITED REVIEW: UV Signature Mutations
  • INVITED REVIEW: Oculocutaneous Albinism in Sub-Saharan Africa: Adverse Sun-Associated Health Effects and Photoprotection
  • RESEARCH ARTICLE: Simultaneous Irradiation with Different Wavelengths of Ultraviolet Light has Synergistic Bactericidal Effect on Vibrio parahaemolyticus
  • RESEARCH ARTICLE:Sun protection Provided by Regulation School Uniforms in Australian Schools: An Opportunity to Improve Personal Sun protection During Childhood
  • RESEARCH ARTICLE: The Employment of a Removable Chitosan-Derivatized Polymeric Sensitizer in the Photooxidation of Polyhydroxylated Water-Pollutants

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Oculocutaneous albinism (OCA) is a group of congenital disorders characterised by a complete or partial lack of melanin in the skin, eyes and hair. The most common form in the Black population of sub-Saharan Africa is OCA2 in which inhibition in the biogenesis of the melanosome and in the processing and transport of melanosomal proteins occur. OCA3 is also found but more rarely; here TRYP1 mutations affect the synthesis of melanin. Individuals with OCA are susceptible to the harmful effects of solar ultraviolet radiation (UVR), including extreme sun sensitivity, sunburn, photophobia, skin cancer and photoaging. OCA represents a grave public health issue in sub-Saharan Africa with a prevalence as high as 1 in 1 000 in some tribes. Given the gravity of the adverse consequences of solar UVR in OCA, health education regarding personal photoprotection as well as effective treatment regimens require urgent recognition and support in sub-Saharan Africa. For further details see the review paper “Oculocutaneous Albinism in Sub-Saharan Africa: Adverse Sun-Associated Health Effects and Photoprotection” by Caradee Wright et al on pages 27 – 32 in this issue.
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