Environmental UV Radiation Research Articles

Discovery of gene cluster for mycosporine-like amino acid biosynthesis from Actinomycetales microorganisms and production of a novel mycosporine-like amino acid by heterologous expression.

Mycosporines and mycosporine-like amino acids (MAAs), including shinorine (mycosporine-glycine-serine) and porphyra-334 (mycosporine-glycine-threonine), are UV-absorbing compounds produced by cyanobacteria, fungi, and marine micro- and macroalgae. These MAAs have the ability to protect these organisms from damage by environmental UV radiation. Although no reports have described the production of MAAs and the corresponding genes involved in MAA biosynthesis from Gram-positive bacteria to date, genome mining of the Gram-positive bacterial database revealed that two microorganisms belonging to the order Actinomycetales, Actinosynnema mirum DSM 43827 and Pseudonocardia sp. strain P1, possess a gene cluster homologous to the biosynthetic gene clusters identified from cyanobacteria. When the two strains were grown in liquid culture, Pseudonocardia sp. accumulated a very small amount of MAA-like compound in a medium-dependent manner, whereas A. mirum did not produce MAAs under any culture conditions, indicating that the biosynthetic gene cluster of A. mirum was in a cryptic state in this microorganism. In order to characterize these biosynthetic gene clusters, each biosynthetic gene cluster was heterologously expressed in an engineered host, Streptomyces avermitilis SUKA22. Since the resultant transformants carrying the entire biosynthetic gene cluster controlled by an alternative promoter produced mainly shinorine, this is the first confirmation of a biosynthetic gene cluster for MAA from Gram-positive bacteria. Furthermore, S. avermitilis SUKA22 transformants carrying the biosynthetic gene cluster for MAA of A. mirum accumulated not only shinorine and porphyra-334 but also a novel MAA. Structure elucidation revealed that the novel MAA is mycosporine-glycine-alanine, which substitutes l-alanine for the l-serine of shinorine.

Assessment of silicone as support to investigate the transformation routes of organic chemicals under environmental conditions and UV exposure. Application to selected fungicides

The suitability of bulk silicone as support to follow the degradation of chemical compounds under environmental conditions and UV radiation is illustrated selecting three fungicides (fenhexamid, FEN; triadimenol, TRI and difenoconazole, DIF) as model compounds. These precursor species were first absorbed in silicone supports (10 mm length × 2 mm i.d. and 0.5 mm thickness) and then kept outdoors for several days (up to 2 months) or exposed to UV radiation (254 nm), from a low pressure mercury lamp, in the laboratory. Degradation of precursor fungicides and by-products formation was followed by liquid chromatography (LC) quadrupole time-of-flight (QTOF) mass spectrometry (MS), after desorption of silicone supports using 0.5 mL of acetonitrile. Half-lives (t(1/2)) measured under UV exposure varied from 5 to 100 min. As regards environmental conditions, the most stable fungicide was DIF, degraded by just 15 % after 2 months; whereas, t(1/2) values of 30 and 83 h were calculated for FEN during summer and autumn, respectively. Supports contained by-products arising from precursor species through de-chlorination, cleavage, hydroxylation, intra-molecular cyclation and oligomerization reactions. Most of them have been previously identified in soil surface, vegetable leaves and water after application of fungicides in agriculture fields. The low cost of silicone tubes (ca. 0.4 Euros), added to their excellent chemical stability and capability to retain precursor species and their by-products, make them ideal supports to follow the transformation routes of organic compounds under environmental and simulated conditions, even for relatively stable species with t(1/2) in the range of weeks or months.

How does epidermal pathology interact with mental state?

The hypothesis is presented that human emotional state is influenced by epidermal pathology via the release from epidermal keratinocytes of a wide variety of chemical mediators (including neurotransmitters) that act on the brain. It has long been recognized that epidermal keratinocytes play a key role in the function of the stratum corneum as an impermeable barrier, and that skin diseases such as atopic dermatitis and psoriasis, which cause itching, sleep disturbance and concern over appearance, are associated with depression and anxiety. On the other hand, epidermal keratinocytes are known to produce and release multiple cytokines and chemical mediators in response to barrier impairment or insult, such as environmental dryness or UV radiation. Elevation of plasma cytokines is associated with depression in cancer patients. Serum levels of oxytocin and glucocorticoid have been shown to influence mental state, and a recent study showed that glucocorticoid is generated in injured epidermis. Thus, there are multiple plausible pathways through which changes in skin can affect emotional state.

Identification of BRAF mutations in eruptive melanocytic nevi: new insights into melanomagenesis?

Evaluation of: Sekulic A, Colgan MB, Davis MD et al. Activating BRAF mutations in eruptive melanocytic naevi. Br. J. Dermatol. 163(5), 1095–1098 (2010).Eruptive melanocytic nevi (EMN) is an unusual phenomenon characterized by the abrupt, simultaneous appearance of hundreds of melanocytic nevi on previously uninvolved sun-exposed skin. The mechanisms underlying this phenomenon are not well understood, but have been associated with both systemic immunosuppression and bullous dermatoses. The paper under evaluation brings new insight into the molecular events underlying EMN development in a patient receiving 6-mercaptopurine immunosuppressive therapy for ulcerative colitis. Sequencing of DNA from 20 eruptive nevi revealed the presence of BRAF V600E mutations in 85% of the lesions tested. The role of mutated BRAF in the initiation and progression of melanoma in conjunction with the strong correlation between nevus number and melanoma risk suggests the need for photoprotection in patients receiving thiopurine therapy. The study under evaluation further points to the possible interaction between environmental mutagens and UV radiation in the acquisition of BRAF mutations that may in turn increase the risk of melanoma development.

Efficacy of Steinernema carpocapsae for control of the lesser peachtree borer, Synanthedon pictipes: Improved aboveground suppression with a novel gel application

Safe and effective tactics are needed for control of the lesser peachtree borer, Synanthedon pictipes (Grote & Robinson), which is a major pest of stone fruits ( Prunus spp) in eastern North America. Virulence of the entomopathogenic nematode, Steinernema carpocapsae (Weiser) , to S. pictipes has been demonstrated in the laboratory. However, achieving field efficacy has been difficult because S. pictipes attacks the tree aboveground where nematodes are subjected to damaging environmental conditions, e.g., UV radiation and desiccation. We investigated the potential of various formulations to improve the efficacy of aboveground applications. First, we screened five potential adjuvants at 2%, 20%, and 40% concentrations in water for toxicity to S. carpocapsae in the laboratory: Anti-Stress, Moisturin®, Nu-Film®, Shatter-Proof, and Transfilm®. In general, the adjuvants did not adversely affect nematode survival except at the highest rate. Subsequently, Shatter-Proof was tested in field trials in 2008 and 2009. S. carpocapsae was applied alone or with Shatter-Proof to peach limbs pre-infested with S. pictipes larvae. Furthermore, the experiments included the following treatments: S. carpocapsae followed by a post-application covering of latex paint, moistened diaper, or a gel spray (Barricade®). Controls of water-only, or water plus Shatter-Proof, Barricade®, or paint (without nematodes) were also included. The nematodes-only treatment failed to reduce S. pictipes survival relative to the water-only control in either year. Additionally, the nematode treatments with Shatter-Proof or paint did not differ from nematodes-only, water-only or their respective control treatments without nematodes. The diaper treatment with nematodes showed some potential as an efficacy enhancer (e.g., insect survival was reduced relative to nematodes-only in one year). In contrast, in both years, nematodes plus Barricade® reduced S. pictipes relative to the controls and the nematodes-only treatment; survival in the Barricade® treatment was 30% and 0% in 2008 and 2009, respectively. We conclude that nematode treatments followed by application of a sprayable gel such as Barricade® can enhance control of S. pictipes and possibly other aboveground pests as well.

Roles of Small, Acid-Soluble Spore Proteins and Core Water Content in Survival of Bacillus subtilis Spores Exposed to Environmental Solar UV Radiation

Spores of Bacillus subtilis contain a number of small, acid-soluble spore proteins (SASP) which comprise up to 20% of total spore core protein. The multiple alpha/beta-type SASP have been shown to confer resistance to UV radiation, heat, peroxides, and other sporicidal treatments. In this study, SASP-defective mutants of B. subtilis and spores deficient in dacB, a mutation leading to an increased core water content, were used to study the relative contributions of SASP and increased core water content to spore resistance to germicidal 254-nm and simulated environmental UV exposure (280 to 400 nm, 290 to 400 nm, and 320 to 400 nm). Spores of strains carrying mutations in sspA, sspB, and both sspA and sspB (lacking the major SASP-alpha and/or SASP-beta) were significantly more sensitive to 254-nm and all polychromatic UV exposures, whereas the UV resistance of spores of the sspE strain (lacking SASP-gamma) was essentially identical to that of the wild type. Spores of the dacB-defective strain were as resistant to 254-nm UV-C radiation as wild-type spores. However, spores of the dacB strain were significantly more sensitive than wild-type spores to environmental UV treatments of >280 nm. Air-dried spores of the dacB mutant strain had a significantly higher water content than air-dried wild-type spores. Our results indicate that alpha/beta-type SASP and decreased spore core water content play an essential role in spore resistance to environmentally relevant UV wavelengths whereas SASP-gamma does not.

From UVs to Metastases: Modeling Melanoma Initiation and Progression in the Mouse

Cutaneous malignant melanoma is highly invasive and capable of metastasizing to distant sites where it is typically resistant to available therapy. While striving to prevent or eradicate melanoma, researchers have two significant advantages not shared by those working on many other cancers. The main environmental etiological agent, UV radiation, is known and melanocytic lesions are excisable for molecular analysis from most stages. Yet knowledge about how UV initiates melanoma has been insufficient to achieve prevention, and the understanding of metastatic mechanisms has been inadequate to reduce mortality. Here, we review the value of melanoma mouse models, focusing on these critical early and late stages.

Diversity and dynamics of Antarctic marine microbial eukaryotes under manipulated environmental UV radiation

In the light of the predicted global climate change, it is essential that the status and diversity of polar microbial communities is described and understood. In the present study, molecular tools were used to investigate the marine eukaryotic communities of Prydz Bay, Eastern Antarctica, from November 2002 to January 2003. Additionally, we conducted four series of minicosm experiments, where natural Prydz Bay communities were incubated under six different irradiation regimes, in order to investigate the effects of natural UV radiation on marine microbial eukaryotes. Denaturing gradient gel electrophoresis (DGGE) and 18S rRNA gene sequencing revealed a eukaryotic Shannon diversity index averaging 2.26 and 2.12, respectively. Phylogenetic analysis of 472 sequenced clones revealed 47 phylotypes, belonging to the Dinophyceae, Stramenopiles, Choanoflagellidae, Ciliophora, Cercozoa and Metazoa. Throughout the studied period, three communities were distinguished: a postwinter/early spring community comprising dinoflagellates, ciliates, cercozoans, stramenopiles, viridiplantae, haptophytes and metazoans; a dinoflagellate-dominated community; and a diatom-dominated community that developed after sea ice breakup. DGGE analysis showed that size fraction and time had a strong shaping effect on the community composition; however, a significant contribution of natural UV irradiance towards microeukaryotic community composition could not be detected. Overall, dinoflagellates dominated our samples and their diversity suggests that they fulfill an important role in Antarctic coastal marine ecosystems preceding ice breakup as well as between phytoplankton bloom events.

Pediatric Melanoma: Risk Factor and Survival Analysis of the Surveillance, Epidemiology and End Results Database

To evaluate risk factors for the development of and factors influencing survival in pediatric melanoma. We evaluated 1,255 children (age < 20 years) and 2,673 young adults (age 20 to 24 years) with melanoma in the 2001 National Cancer Institute (NCI) Surveillance, Epidemiology and End Results (SEER) database. We estimated exposure to UV radiation based on Environmental Protection Agency (EPA) measurements. The incidence of pediatric melanoma increased 46% (95% CI, 40 to 52) per year of age and 2.9% (95% CI, 2.1 to 3.6) per year from 1973 to 2001. Incidence rates were lower in black patients (-95%; 95% CI, -98 to -90) compared with white patients and in male patients (-39%; 95% CI -46 to -31) compared with females. Increased ambient UV radiation was associated with elevated risk (19% per kJ; 95% CI, 9 to 30). Children with melanoma had a 5-year melanoma-specific survival of 93.6% (95% CI, 91.9 to 94.9), which improved from 1973 to 2001. The hazard ratio of death from melanoma increased with male sex; older age; advanced disease; location of the primary other than extremities or torso; earlier year of diagnosis; and previous cancer. The incidence of melanoma in the United States is increasing rapidly in children. Risk factors for pediatric melanoma include being white, being female, increasing age, and environmental UV radiation. Survival is decreased for children and adolescents with unfavorable prognostic factors (male sex, unfavorable site, and/or second primary or regional or distant metastasis). More effective therapeutic strategies are needed for these groups.

Exposure Geometry and Spectral Environment Determine Photobiological Effects on the Human Eye¶†

ABSTRACTPhotobiological effects upon the human retina, cornea and lens are highly dependent on the optical exposure geometry as well as spectral characteristics of the exposure. The organ of sight is exquisitely sensitive to light because it performs well in very low nighttime illumination levels and yet it also must adapt to extremely bright environments where light exposures are greater by many orders of magnitude. The eye has evolved to protect itself reasonably well against excessive exposure in bright environments. The retina is minimally exposed in extremely bright environments and the cornea and lens are surprisingly well protected in harsh environments. Although these protective mechanisms are good, they are not perfect and adverse changes from both acute and chronic exposures to sunlight still exist. The geometrical protective factors must be understood and appreciated whenever assessing potential adverse effects of environmental UV radiation and light on ocular structures. These natural ocular protective factors also work with the ever‐changing spectrum of sunlight and the different spectral distribution of light and UV radiation across the eye's field of view. Spectral characteristics of the ocular media are also important. One can visualize a series of intraocular color filters that progressively filter shorter wavelengths and thereby aid in color vision, reduce the impact of chromatic aberrations and significantly reduce the optical radiation hazards to the lens and retina.

Exposure Geometry and Spectral Environment Determine Photobioligical Effects on the Human Eye

Photobiological effects upon the human retina, cornea and lens are highly dependent on the optical exposure geometry as well as spectral characteristics of the exposure. The organ of sight is exquisitely sensitive to light because it performs well in very low nighttime illumination levels and yet it also must adapt to extremely bright environments where light exposures are greater by many orders of magnitude. The eye has evolved to protect itself reasonably well against excessive exposure in bright environments. The retina is minimally exposed in extremely bright environments and the cornea and lens are surprisingly well protected in harsh environments. Although these protective mechanisms are good, they are not perfect and adverse changes from both acute and chronic exposures to sunlight still exist. The geometrical protective factors must be understood and appreciated whenever assessing potential adverse effects of environmental UV radiation and light on ocular structures. These natural ocular protective factors also work with the ever-changing spectrum of sunlight and the different spectral distribution of light and UV radiation across the eye's field of view. Spectral characteristics of the ocular media are also important. One can visualize a series of intraocular color filters that progressively filter shorter wavelengths and thereby aid in color vision, reduce the impact of chromatic aberrations and significantly reduce the optical radiation hazards to the lens and retina.

Role of pigmentation in protecting Bacillus sp. endospores against environmental UV radiation

Bacillus endospores show different kinds of pigmentation. Red-pigmented spores of Bacillus atrophaeus DSM 675, dark-gray spores of B. atrophaeus T DSM 7264 and light-gray spores of B. subtilis DSM 5611 were used to study the protective role of the pigments in their resistance to defined ranges of environmental UV radiation. Spores of B. atrophaeus DSM 675 possessing a dark-red pigment were 10 times more resistant to UV-A radiation than those of the other two investigated strains, whereas the responses to the more energetic UV-B and UV-C radiation were identical in all three strains. The methanol fraction of the extracted pigment from the spores absorbs in the associated wavelength area. These results indicate that the carotene-like pigment of spores of B. atrophaeus DSM 675 affects the resistance of spores to environmental UV-A radiation.

Biological UV dosimetry using the DLR-biofilm.

Changes of environmental UV radiation as part of global atmospheric changes will influence the biosphere substantially. The determination of the biological effects of these changes requires accurate and reliable UV monitoring systems that weight the spectral irradiance according to the biological responses under consideration. Biological UV dosimeters, which directly weight the incident UV components of sunlight in relation to the effectiveness of the different wavelengths and the potential interactions between them, can complement weighted physical UV measurements. Up to now several UV-dependent endpoints in biomolecules (e.g. uracil, DNA, provitamin D3), bacteriophages (e.g. T7), bacteria (e.g.E. coli, B. subtilis) and cultured eukaryotic cells have been suggested as sensing elements in biological UV dosimeters. One example is the DLR-biofilm consisting of immobilised spores of the bacterium B. subtilis as a UV sensor. It weights per se the incident UV radiation according to its DNA-damaging effectiveness. In several examples the applicability of the DLR-biofilm technique for personal UV dosimetry as well as for the measurement of the biologically weighted irradiance of the sun and of artificial UV sources is demonstrated.

Structure of dried cellular alginate matrix containing fillers provides extra protection for microorganisms against UVC radiation.

Soil microorganisms in general and biocontrol agents in particular are very sensitive to UV light. The packaging of biocontrol microorganisms into cellular solids has been developed as a means of reducing loss caused by exposure to environmental UV radiation. The bacterial and fungal biocontrol agents Pantoea agglomerans and Trichoderma harzianum were immobilized in freeze-dried alginate beads containing fillers and subjected to 254 nm UV radiation (UVC). Immobilization of cells in freeze-dried alginate-glycerol beads resulted in greater survival after UV irradiation than for a free cell suspension. Adding chitin, bentonite or kaolin as fillers to the alginate-glycerol formulation significantly increased bacterial survival. Immobilization in alginate-glycerol-kaolin beads resulted in the highest levels of survival. The transmissive properties of the dried hydrocolloid cellular solid had a major influence on the amount of protection by the cell carrier. Dried alginate matrix (control) transmitted an average of 7.2% of the radiation. Filler incorporation into the matrix significantly reduced UV transmission: Alginate with kaolin, bentonite and chitin transmitted an average of 0.15, 0.38 and 3.4% of the radiation, respectively. In addition, the filler inclusion had a considerable effect on the bead's average wall thickness, resulting in a approximately 1.5- to threefold increase relative to beads based solely on alginate. These results suggest that the degree of protection of entrapped microorganisms against UVC radiation is determined by the UV-transmission properties of the dried matrix and the cellular solid's structure. It is concluded that for maximum protection against UV-radiation-induced cell loss, biocontrol microorganisms should be immobilized in alginate-glycerol beads containing kaolin.

Assessment of integrated solar ultraviolet radiation by PM-355 detectors

The increase in environmental solar UV radiation due to depletion of ozone layer is a recent challenge to human health (skin cancer and eye effects) in countries having clear skies. Therefore, applying integrated, passive and inexpensive techniques to assess solar UV radiation is very much essential. Measurements of environmental solar UV radiation in Dhahran, Saudi Arabia area were carried out for a period of two months in the summer period in 1996 using two techniques in parallel namely: passive nuclear track detectors and active solar UV radiometers. Some of the nuclear track detectors were mounted in different conditions such as: under shadow band, on solar tracking mechanism following the solar rays. Others were mounted on perpendicular, tilted and horizontal surfaces in sunlight. All detectors were attached to a wooden background of the same thickness (0.5 cm) to eliminate interference of the heat effect of various support materials and have uniformity of the support materials. The assessment was carried out for different periods extending from two to nine weeks continuously. The investigated period covered the hottest months in Saudi Arabia (July and August) when the sky was clear of clouds. The results indicate linear correlation between alpha track diameters and the integrated exposure to solar UV as measured by the solar UV radiometer for all nuclear track detector positions and orientations. The highest slope has been observed for the detectors placed on solar tracking mechanism following the solar rays and the lowest from detectors oriented under the shadow band on horizontal position (measuring the diffused UV radiation only). The results show that most of the measured UV radiation (60%) were from the diffused UV radiation. The characteristics of the upper layer of the detectors are changed after chemical etching very quickly, with increase in the exposure time to UV solar radiation at certain orientation. The results encourage the use of nuclear track detectors for environmental and personal solar UV dosimetry on a large scale in Saudi Arabia and similar hot and clear-sky countries.

Quantification of biologically effective environmental UV irradiance

To determine the impact of environmental UV radiation on human health and ecosystems demands monitoring systems that weight the spectral irradiance according to the biological responses under consideration. In general, there are three different approaches to quantify a biologically effective solar irradiance. (i) weighted spectroradiometry where the biologically weighted radiometric quantities are derived from spectral data by multiplication with an action spectrum of a relevant photobiological reaction, e.g. erythema, DNA damage, skin cancer, reduced productivity of terrestrial plants and aquatic foodweb, (ii) wavelength integrating chemical-based or physical dosimetric systems with spectral sensitivities similar to a biological response curve, and (iii) biological dosimeters that directly weight the incident UV components of sunlight in relation to the effectiveness of the different wavelengths and to interactions between them. Most biological dosimeters, such as bacteria, bacteriophages, or biomolecules, are based on the UV sensitivity of DNA. If precisely characterized, biological dosimeters are applicable as field and personal dosimeters.

Spore dosimetry of solar UV radiation: applications to monitoring of daily irradiance and personal exposure.

Environmental UV radiation can be quantified using spore dosimetry, which measures the inactivation of repair-deficient Bacillus subtilis spores dried on a membrane filter. The system exhibits highly selective sensitivity to UV radiation, not being affected by various environmental adversities, such as high and low temperature and humidity. Biologically-effective dose rate and cumulative dose of ambient radiation are measurable under various conditions at various places on the earth, including tropical, temperate, and polar sites. Applications to monitor the exposure at the surface of organisms including humans and plants have also been advanced.

Biological UV dosimeters in the assessment of the biological hazard from environmental radiation

To determine the impact of environmental UV radiation, biological dosimeters that weight directly the incident UV components of sunlight have been developed, improved and evaluated in the frame of the BIODOS project. Four DNA-based biological dosimeters ((i) phage T7, (ii) uracil thin layer, (iii) spore dosimeter and (iv) DLR-biofilm) have been assessed from the viewpoint of their biological relevance, spectral response and quantification of their biological effectiveness. The biological dosimeters have been validated by comparing their readings with weighted spectroradiometer data, by comparison with other biological doses, as well as with the determined amounts of DNA UV photoproducts. The data presented here demonstrate that the biological dosimeters are potentially reliable field dosimeters for measuring the integrated biologically effective irradiance for DNA damage.

Intrinsic and extrinsic biomarkers for the assessment of risks from environmental UV radiation.

In the last decades the knowledge of the effects of UV radiation on human health, especially in skin cancerogenesis, but also in immunsuppression, photoaging, eye damages, has enlarged strongly. The increasing solar UV radiation and changes in life style strengthen the necessity to identify and quantitate intrinsic biomarkers which are indicative for the individual UV susceptibility and the accumulated individual UV burden. For the risk assessment of potentially deleterious UV effects extrinsic biomarkers have to be developed and tested as personal biological UV dosimeters. One example for such a well characterized biological UV dosimeter is the DLR-biofilm which consists of spores of the bacterium Bacillus subtilis as UV sensitive target.

Biological monitoring of radiation exposure

Complementary to physical dosimetry, biological dosimetry systems have been developed and applied which weight the different components of environmental radiation according to their biological efficacy. They generally give a record of the accumulated exposure of individuals with high sensitivity and specificity for the toxic agent under consideration. Basically three different types of biological detecting/ monitoring systems are available: (i) intrinsic biological dosimeters that record the individual radiation exposure (humans, plants, animals) in measurable units. For monitoring ionizing radiation exposure, in situ biomarkers for genetic (e.g. chromosomal aberrations in human lymphocytes, germ line minisatellite mutation rates) or metabolic changes in serum, plasma and blood (e.g. serum lipids, lipoproteins, lipid peroxides, melatonin, antibody titer) have been used. (ii) Extrinsic biological dosimeters/indicators that record the accumulated dose in biological model systems. Their application includes long-term monitoring of changes in environmental UV radiation and its biological implications as well as dosimetry of personal UV exposure. (iii) Biological detectors/biosensors for genotoxic substances and agents such as bacterial assays (e.g. Ames test, SOS-type test) that are highly sensitive to genotoxins with high specificity. They may be applicable for different aspects in environmental monitoring including the International Space Station.