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With the rise of bacterial infections and antibiotic resistance, spectroscopic devices originally developed for bacterial detection have shown promise to rapidly identify bacterial strains and determine the ratio of live to dead bacteria. However, the detection of the photoreactivated pathogens remains a critical concern. This study utilizes fluorescence and Raman spectroscopy to analyze bacterial responses to UV irradiation and subsequent photoreactivation. Our experimental results reveal limitations in fluorescence spectroscopy for detecting photoreactivated bacteria, as the intense fluorescence of tryptophan and tyrosine amino acids masks the fluorescence emitted by thymine molecules. Conversely, Raman spectroscopy proves more effective, showing a detectable decrease in band intensities of E. coli bacteria at 1248 and 1665 cm−1 after exposure to UVC radiation. Subsequent UVA irradiation results in the partial restoration of these band intensities, indicating DNA repair and bacterial photoreactivation. This enhanced understanding aims to improve the accuracy and effectiveness of these spectroscopic tools in clinical and environmental settings. [ABSTRACT FROM AUTHOR]

Ultraviolet radiation (UVR) has positive and negative impacts on organisms and affects entire ecosystems. It is currently receiving attention because of the interactions of UVR with changes in climate that are likely to affect agriculture and food security.A review is provided on the effects of different types of UVR on the survival, development and reproduction of insects, collembolans and mites. The foci are on how UVR is used in pest control and how it affects arthropod coloration and distribution.Direct exposure to UV‐A, UV‐B and UV‐C delays development and reduces survival and host‐seeking ability of arthropods; immature stages are more sensitive than the adults. Increased exposure of crops to UVR has indirect effects on herbivory, and regions with high UVR levels may permit crop production in the absence of certain pest insect species.The Bunsen‐Roscoe law of reciprocity was upheld for Diaphorina citri and Tetranychus urticae under the range of irradiances and durations of exposure used in two studies, which showed that, for a constant dose, the effects of low irradiances of long durations were equivalent to those of higher irradiances of shorter durations.DNA damage caused by UV‐C and UV‐B can be repaired by photoreactivation; both white light and UV‐A are effective. [ABSTRACT FROM AUTHOR]

Abstract Background 6 − 4 photoproducts are the second most common UV-induced DNA lesions after cyclobutane pyrimidine dimers. In plants, they are mainly repaired by photolyases in a process called photoreactivation. While pyrimidine dimers can be deleterious, leading to mutagenesis or even cell death, 6 − 4 photoproducts can activate specific signaling pathways. Therefore, their removal is particularly important, especially for plants exposed to high UV intensities due to their sessile nature. Although photoreactivation in nuclear DNA is well-known, its role in plant organelles remains unclear. In this paper we analyzed the activity and localization of GFP-tagged AtUVR3, the 6 − 4 photoproduct specific photolyase. Results Using transgenic Arabidopsis with different expression levels of AtUVR3, we confirmed a positive trend between these levels and the rate of 6 − 4 photoproduct removal under blue light. Measurements of 6 − 4 photoproduct levels in chloroplast and nuclear DNA of wild type, photolyase mutants, and transgenic plants overexpressing AtUVR3 showed that the photoreactivation is the main repair pathway responsible for the removal of these lesions in both organelles. The GFP-tagged AtUVR3 was predominantly located in nuclei with a small fraction present in chloroplasts and mitochondria of transgenic Arabidopsis thaliana and Nicotiana tabacum lines. In chloroplasts, this photolyase co-localized with the nucleoid marked by plastid envelope DNA binding protein. Conclusions Photolyases are mainly localized in plant nuclei, with only a small fraction present in chloroplasts and mitochondria. Despite this unbalanced distribution, photoreactivation is the primary mechanism responsible for the removal of 6 − 4 photoproducts from nuclear and chloroplast DNA in adult leaves. The amount of the AtUVR3 photolyase is the limiting factor influencing the photoreactivation rate of 6 − 4 photoproducts. The efficient photoreactivation of 6 − 4 photoproducts in 35S: AtUVR3-GFP Arabidopsis and Nicotiana tabacum is a promising starting point to evaluate whether transgenic crops overproducing this photolyase are more tolerant to high UV irradiation and how they respond to other abiotic and biotic stresses under field conditions.

Background: 6 − 4 photoproducts are the second most common UV-induced DNA lesions after cyclobutane pyrimidine dimers. In plants, they are mainly repaired by photolyases in a process called photoreactivation. While pyrimidine dimers can be deleterious, leading to mutagenesis or even cell death, 6 − 4 photoproducts can activate specific signaling pathways. Therefore, their removal is particularly important, especially for plants exposed to high UV intensities due to their sessile nature. Although photoreactivation in nuclear DNA is well-known, its role in plant organelles remains unclear. In this paper we analyzed the activity and localization of GFP-tagged AtUVR3, the 6 − 4 photoproduct specific photolyase. Results: Using transgenic Arabidopsis with different expression levels of AtUVR3, we confirmed a positive trend between these levels and the rate of 6 − 4 photoproduct removal under blue light. Measurements of 6 − 4 photoproduct levels in chloroplast and nuclear DNA of wild type, photolyase mutants, and transgenic plants overexpressing AtUVR3 showed that the photoreactivation is the main repair pathway responsible for the removal of these lesions in both organelles. The GFP-tagged AtUVR3 was predominantly located in nuclei with a small fraction present in chloroplasts and mitochondria of transgenic Arabidopsis thaliana and Nicotiana tabacum lines. In chloroplasts, this photolyase co-localized with the nucleoid marked by plastid envelope DNA binding protein. Conclusions: Photolyases are mainly localized in plant nuclei, with only a small fraction present in chloroplasts and mitochondria. Despite this unbalanced distribution, photoreactivation is the primary mechanism responsible for the removal of 6 − 4 photoproducts from nuclear and chloroplast DNA in adult leaves. The amount of the AtUVR3 photolyase is the limiting factor influencing the photoreactivation rate of 6 − 4 photoproducts. The efficient photoreactivation of 6 − 4 photoproducts in 35S: AtUVR3-GFP Arabidopsis and Nicotiana tabacum is a promising starting point to evaluate whether transgenic crops overproducing this photolyase are more tolerant to high UV irradiation and how they respond to other abiotic and biotic stresses under field conditions. [ABSTRACT FROM AUTHOR]

The use of light to promote health, reduce harm, and restore functionality is a novel, non-accumulative physical strategy that contrasts with the predominantly chemical approaches used in Western medicine. This strategy may serve as an independent function for healthcare professionals and warrants further exploration. Photoreactivation, achieved by adjusting patients' physiological clocks at different times, utilizing specific wavelengths, varying color temperatures, and using illuminance, is a potent tool for improving mood and sleep quality, regulating autonomic nervous system balance, enhancing attention, and delaying cognitive decline. Light therapy is a rapidly expanding field in healthcare that offers new opportunities to enhance quality of life, prevent diseases, and improve overall well-being. This article elucidates the fundamental concepts of photoreactivation, explores its application across diverse health domains, examines its future development prospects, and discusses the challenges faced by photoreactivation and related solutions to ensure the responsible use of light to enhance and restore physiological and psychological functions. [ABSTRACT FROM AUTHOR]

Studies have demonstrated bacterial inactivation by radiations at wavelengths between 400 and 500 nm emitted by low-power light sources. The phototoxic activity of these radiations could occur by oxidative damage in DNA and membrane proteins/lipids. However, some cellular mechanisms can reverse these damages in DNA, allowing the maintenance of genetic stability. Photoreactivation is among such mechanisms able to repair DNA damages induced by ultraviolet radiation, ranging from ultraviolet A to blue radiations. In this review, studies on the effects of violet and blue lights emitted by low-power LEDs on bacteria were accessed by PubMed, and discussed the repair of ultraviolet-induced DNA damage by photoreactivation mechanisms. Data from such studies suggested bacterial inactivation after exposure to violet (405 nm) and blue (425–460 nm) radiations emitted from LEDs. However, other studies showed bacterial photoreactivation induced by radiations at 348–440 nm. This process occurs by photolyase enzymes, which absorb photons at wavelengths and repair DNA damage. Although authors have reported bacterial inactivation after exposure to violet and blue radiations emitted from LEDs, pre-exposure to such radiations at low fluences could activate the photolyases, increasing resistance to DNA damage induced by ultraviolet radiation. [ABSTRACT FROM AUTHOR]

Objective To investigate the reactivation of Escherichia coli in water after ultraviolet disinfection and the effects of ultraviolet dose, reactivation light intensity, low temperature, and dark time on the photoreactivation of Escherichia coli in water. Methods Escherichia coli was artificially contaminated into sterilized tap water, the irradiation distance and time of ultraviolet lamp were adjusted, and the test conditions before and after ultraviolet disinfection were changed, and then the number of reactivated bacteria was counted by nutrient agar pouring method. The reactivation rate of Escherichia coli was calculated and compared under different resurrection conditions. Results When the reactivation light intensity was constant, the photoreactivation rate of Escherichia coli decreased with the increase of ultraviolet dose, and there was a negative correlation between 8 h photoreactivation rate and ultraviolet dose (R2=0.954, P < 0,001), When the ultraviolet dose was constant, the photoreactivation rate of Escherichia coli increased with the increase of reactivation light intensity. Under the light intensity of 28& 386, and 504 Lux, the photoreactivation rates of Escherichia coli for 8 hours were (0.009±0.001) %, (0.020±0.002) %，and (0.075±0.008) %，respectively. There was no obvious photoreactivation of Escherichia coli after ultraviolet disinfection in water samples treated with low temperature, and the photoreactivation rate of Escherichia coli in 8 hours was (0.012 ± 0.003) which was significantly lower than that in water samples without low temperature treatment (0.113 ±0.004) %. The dark repair ability of Escherichia coli was weak and the reactivation phenomenon was not obvious. The average reactivation rate of Escherichia coli treated by avoiding light for different time was basically the same from initial light to 8 h light reactivation rate, and the 8 h light reactivation rate was similar. Conclusion Increasing ultraviolet dose, reducing reactivation light intensity and low temperature treatment can effectively reduce the degree of photoreactivation of Escherichia coli., while avoiding light treatment cannot effectively inhibit the photoreactivation of Escherichia coli. [ABSTRACT FROM AUTHOR]

Lower plants such as bryophytes often encounter submergence stress, even in low precipitation conditions. Our study aimed to understand the mechanism of submergence tolerance to withstand this frequent stress in moss (Semibarbula orientalis) during the day and at night. These findings emphasise that light plays a crucial role in photoreactivation of PSII in S. orientalis, which indicates that light not only fuels photosynthesis but also aids in repairing the photosynthetic machinery in plants. Submergence negatively affects photosynthesis parameters such as specific and phenomenological fluxes, density of functional PSII reaction centres (RC/CS), photochemical and non-photochemical quenching (Kp and Kn), quantum yields (φP0, φE0, φD0), primary and secondary photochemistry, performance indices (PIcs and PIabs), etc. Excessive antenna size caused photoinhibition at the PSII acceptor side, reducing the plastoquinone pool through the formation of PSII triplets and reactive oxygen species (ROS). This ROS-induced protein and PSII damage triggered the initiation of the repair cycle in presence of sunlight, eventually leading to the resumption of PSII activity. However, ROS production was regulated by antioxidants like superoxide dismutase (SOD) and catalase (CAT) activity. The rapid recovery of RS/CS observed specifically under sunlight conditions emphasises the vital role of light in enabling the assembly of essential units, such as the D1 protein of PSII, during stress in S. orientalis. Overall, light is instrumental in restoring the photosynthetic potential in S. orientalis growing under submergence stress. Additionally, it was observed that plants subjected to submergence stress during daylight hours rapidly recover their photosynthetic performance. However, submergence stress during the night requires a comparatively longer period for the restoration of photosynthesis in the moss S. orientalis. [ABSTRACT FROM AUTHOR]

The anti-ultraviolet (UV) role of a Rad4-Rad23-Rad33 complex in budding yeast relies on nucleotide excision repair (NER), which is mechanistically distinct from photorepair of DNA lesions generated under solar UV irradiation but remains poorly known in filamentous fungi. Here, two nucleus-specific Rad4 paralogs (Rad4A and Rad4B) and nucleocytoplasmic shuttling Rad23 ortholog are functionally characterized by multiple analyses of their null mutants in Metarhizium robertsii, an entomopathogenic fungus lacking Rad33. Rad4A was proven to interact with Rad23 and contribute significantly more to conidial UVB resistance (90%) than Rad23 (65%). Despite no other biological function, Rad4A exhibited a very high activity in photoreactivation of UVB-impaired/inactivated conidia by 5-h light exposure due to its interaction with Rad10, an anti-UV protein clarified previously to have acquired a similar photoreactivation activity through its interaction with a photolyase in M. robertsii. The NER activity of Rad4A or Rad23 was revealed by lower reactivation rates of moderately impaired conidia after 24-h dark incubation but hardly observable at the end of 12-h dark incubation, suggesting an infeasibility of its NER activity in the field where nighttime is too short. Aside from a remarkable contribution to conidial UVB resistance, Rad23 had pleiotropic effect in radial growth, aerial conidiation, antioxidant response, and cell wall integrity but no photoreactivation activity. However, Rad4B proved redundant in function. The high photoreactivation activity of Rad4A unveils its essentiality for M. robertsii's fitness to solar UV irradiation and is distinct from the yeast homolog's anti-UV role depending on NER. Resilience of solar ultraviolet (UV)-impaired cells is crucial for the application of fungal insecticides based on formulated conidia. Anti-UV roles of Rad4, Rad23, and Rad33 rely upon nucleotide excision repair (NER) of DNA lesions in budding yeast. Among two Rad4 paralogs and Rad23 ortholog characterized in Metarhizium robertsii lacking Rad33, Rad4A contributes to conidial UVB resistance more than Rad23, which interacts with Rad4A rather than functionally redundant Rad4B. Rad4A acquires a high activity in photoreactivation of conidia severely impaired or inactivated by UVB irradiation through its interaction with Rad10, another anti-UV protein previously proven to interact with a photorepair-required photolyase. The NER activity of either Rad4A or Rad23 is seemingly extant but unfeasible under field conditions. Rad23 has pleiotropic effect in the asexual cycle in vitro but no photoreactivation activity. Therefore, the strong anti-UV role of Rad4A depends on photoreactivation, unveiling a scenario distinct from the yeast homolog's NER-reliant anti-UV role. [ABSTRACT FROM AUTHOR]

In certain countries where fresh water is in short supply, the effluents from wastewater treatment plants are being recycled for other uses. For quality assurance, tertiary disinfection treatments are required. This study aims to evaluate the inactivating efficacy with an ultraviolet (UV) system on fecal bacteria from effluents of urban wastewater treatment facilities and the post-treatment influence of the environmental illumination. The effect from different UV doses was determined for native and standardized lyophilized strains of Escherichia coli right after the irradiation as well as after 24 h of incubation under light or dark conditions. To achieve 3 log-reductions of the initial bacterial concentration, a UV dose of approximately 12 mJ cm−2 is needed for E. coli ATCC 8739 and native E. coli. However, there is a risk of the reactivation of 0.19% and 1.54% of the inactivated organisms, respectively, if the treated organisms are stored in an illuminated environment. This suggests that the post-treatment circumstances affect the treatment success; storing the treated water under an illuminated environment may pose a risk even if an effective inactivation was achieved during the irradiation. [ABSTRACT FROM AUTHOR]

The Rad4-Rad23-Rad33 complex plays an essential anti-ultraviolet (UV) role depending on nucleotide excision repair (NER) in budding yeast but has been rarely studied in filamentous fungi, which possess two Rad4 paralogs (Rad4A/B) and orthologous Rad23 and rely on the photorepair of UV-induced DNA lesions, a distinct mechanism behind the photoreactivation of UV-impaired cells. Previously, nucleocytoplasmic shuttling Rad23 proved to be highly efficient in the photoreactivation of conidia inactivated by UVB, a major component of solar UV, due to its interaction with Phr2 in Beauveria bassiana, a wide-spectrum insect mycopathogen lacking Rad33. Here, either Rad4A or Rad4B was proven to localize exclusively in the nucleus and interact with Rad23, which was previously shown to interact with the white collar protein WC2 as a regulator of two photorepair-required photolyases (Phr1 and Phr2) in B. bassiana. The Δrad4A mutant lost ~80% of conidial UVB resistance and ~50% of activity in the photoreactivation of UVB-inactivated conidia by 5 h light exposure. Intriguingly, the reactivation rates of UVB-impaired conidia were observable only in the presence of rad4A after dark incubation exceeding 24 h, implicating extant, but infeasible, NER activity for Rad4A in the field where night (dark) time is too short. Aside from its strong anti-UVB role, Rad4A played no other role in B. bassiana's lifecycle while Rad4B proved to be functionally redundant. Our findings uncover that the anti-UVB role of Rad4A depends on the photoreactivation activity ascribed to its interaction with Rad23 linked to WC2 and Phr2 and expands a molecular basis underlying filamentous fungal adaptation to solar UV irradiation on the Earth's surface. [ABSTRACT FROM AUTHOR]

Ultraviolet (UV)-C light for disinfection has experienced a surge in popularity since the outbreak of COVID-19. Currently, many different UV-C systems, with varied properties that impact disinfection performance, are available on the market. Therefore this review aims to bundle the available information on UV-C disinfection to obtain an overview of its advantages, disadvantages, and performance-influencing parameters. A literature search was performed using the snowball search method in Google Scholar and PubMed with the following keywords: UV-C disinfection, UV-C dose, UV-C light source, UV-C repair mechanism, UV-C photoreactivation, and UV-C disinfection standards. The main parameters of UV-C disinfection are wavelength, dose, relative humidity, and temperature. There is no consensus about their optimal values, but, in general, light at a high dose and a spectrum of wavelengths containing 260 nm is preferred in an environment at room temperature with low relative humidity. This light can be generated by mercury-vapour, light-emitting diode (LED), pulsed-xenon, or excimer lamps. Multiple factors are detrimental to disinfection performance such as shadowing, a rough surface topography, a high level of contamination, repair mechanisms, and the lack of standardization. Also, there are health and safety risks associated with the UV-C technology when used in the proximity of people. UV-C disinfection systems have promising features and the potential to improve in the future. However, clarifications surrounding the different parameters influencing the technologies' effectiveness in hospital environment are needed. Therefore UV-C disinfection should currently be considered for low-level rather than high-level disinfection. [ABSTRACT FROM AUTHOR]

Ultraviolet disinfection has been extensively studied in recent years, especially in bacteria; however, there are still insufficient studies in fungal spores. Moreover, most studies use static batch reactors instead of continuous flow reactors, which are used mainly at the industrial scale. In the present work, the inactivation and reactivation characteristics of two species of filamentous fungi were studied using a single-pass flow-through UV-C reactor (FTR). For this purpose, Aspergillus niger and Penicillium sp. spores were suspended in water and circulated through the reactor at different UV-C doses. The effects on inactivation and reactivation after 24 in either light or dark conditions were studied. The two fungal strains studied show different UV-C treatment resistance and damage repair capacity. With the experimented FTR system, an inactivation efficiency of up to 2 log units (99% removal) was achieved with doses of 220.1 ± 24.3 mJ cm−2 in the case of Aspergillus niger and 123.8 ± 6.3 mJ cm−2 in the case of Penicillium sp. The effect of dark repair is negligible, while the photoreactivation process is relevant in the case of Penicillium sp., since D2 increased by 53.8% just after UV-C exposure due to photoreactivation. In general, A. niger is more UV-C resistant than Penicillium sp.; however, the latter has a greater capacity to photoreactivate.

Ultraviolet disinfection is an important method for controlling the large-scale outbreaks of diseases in aquaculture. As a novel and promising light source, ultraviolet light-emitting diode (UV-LED) has the advantages of safety, high efficiency and no environmental pollution risks. However, it remains unclear whether UV-LEDs can replace traditional UV light sources for aquaculture water treatment processes. Present study aimed to investigate the efficacy of UVC-LEDs (265 nm) on pathogenic bacteria, specifically Aeromonas salmonicida and Escherichia coli. The effects of UVC-LED dose, light conditions, and temperature on bacterial reactivation were also investigated. The results showed that exposure to UVC-LED effectively inactivated both types of bacteria. To achieve 4.5-log inactivation of A. salmonicida and E. coli, 24 mJ/cm2 and 28 mJ/cm2 UVC-LED irradiation were required, and the inactivation rate increased with increasing UVC-LED fluence. Both A. salmonicida and E. coli were revived after UVC-LED disinfection, and photoreactivation was significantly higher than dark reactivation. Bacterial reactivation rate due to high-dose UVC-LED treatment was significantly lower than that of low-dose. After 72 h of reactivation, photoreactivation and dark reactivation rates were 1 ± 0.4% and 2.2 ± 0.2%for A. salmonicida, and 0.02% and 0% for E. coli, respectively. Besides, the photoreactivation rates for the two bacteria exhibited different correlations with temperature. The highest photoreactivation rate for A. salmonicida was 68.7 ± 4% at 20°C, while the highest photoreactivation rate for E. coli was 53.98 ± 2.9% at 15°C for 48 h. This study reveals the rapid and efficient inactivation of bacteria by UVC-LED, and elucidates the mechanism and influencing factors for inactivation and reactivation by UVC-LED. The study also highlights that adequate UVC-LED irradiation and avoidance of visible light after UVC-LED disinfection can effectively inhibit bacterial reactivation. Our findings form a reference for the design and operation of UV disinfection in aquaculture.

Beauveria bassiana serves as a main source of global fungal insecticides, which are based on the active ingredient of formulated conidia vulnerable to solar ultraviolet (UV) irradiation and restrained for all-weather application in green agriculture. The anti-UV proteins Rad1 and Rad10 are required for the nucleotide excision repair (NER) of UV-injured DNA in model yeast, but their anti-UV roles remain rarely exploredin filamentous fungi. Here, Rad1 and Rad10 orthologues that accumulated more in the nuclei than the cytoplasm of B. bassiana proved capable of reactivating UVB-impaired or UVB-inactivated conidia efficiently by 5h light exposure but incapable of doing so by 24 h dark incubation (NER) if the accumulated UVB irradiation was lethal. Each orthologue was found interacting with the other and two white collar proteins (WC1 and WC2), which proved to be regulators of two photolyases (Phr1 and Phr2) and individually more efficient in the photorepair of UVB-induced DNA lesions than either photolyase alone. The fungal photoreactivation activity was more or far more compromised when the protein–protein interactions were abolished in the absence of Rad1 or Rad10 than when either Phr1 or Phr2 lost function. The detected protein–protein interactions suggest direct links of either Rad1 or Rad10 to two photolyase regulators. In B. bassiana, therefore, Rad1 and Rad10 tied to the photolyase regulators have high activities in the photoprotection of formulated conidia from solar UV damage but insufficient NER activities in the field, where night (dark) time is too short, and no other roles in the fungal lifecycle in vitro and in vivo. [ABSTRACT FROM AUTHOR]

Ultraviolet (UV) disinfection is an increasingly developed disinfection technology commonly used to kill pathogens in water by ultraviolet irradiation. However, in many ultraviolet disinfection applications, the potential repair of microbial ultraviolet damage is a problem of great concern. Given the photoreactivation of Escherichia coli (E. coli) after ultraviolet disinfection, this article reviews the effect of reactivation light intensity on the photoreactivation of Escherichia coli. The study showed that the light intensity of reactivation significantly affects the photoreactivation level of E. coli, and the influence law varies according to the different ultraviolet doses used in disinfection treatment. At a low UV dose, the light intensity does not affect the degree of photoreactivation of E. coli. Nevertheless, somewhat under a high UV dose, there is a threshold of photoreactivation intensity. When the intensity is lower than this value, E. coli photoreactivation is generally unnoticeable. However, the reactivation effect is significant when the intensity is higher than this value. It was also found that E. coli was inhibited when the photoreactivation intensity was zero (dark treatment), and exposure to high-intensity sunlight also had a harmful effect on the photoreactivation. [ABSTRACT FROM AUTHOR]

• The combination of UV and NH 2 Cl exhibited better performance than individual processes. • UV/NH 2 Cl performed better inactivation efficiency than that of UV/Cl 2. • The mechanisms of the synergistic effect during the UV/NH 2 Cl process were analyzed. • UV/NH 2 Cl can observably increase the membrane damage and intracellular ROS level. Ultraviolet (UV)/monochloramine (NH 2 Cl) as an advanced oxidation process was firstly applied for Aspergillus spores inactivation. This study aims to: i) clarify the inactivation and photoreactivation characteristics of UV/NH 2 Cl process, ii) compared with UV/Cl 2 in inactivation efficiency, photoreactivation and energy consumption. The results illustrated that UV/NH 2 Cl showed better inactivation efficiency than that of UV alone and UV/Cl 2 , and could effectively control the photoreactivation. For instance, the inactivation rates for Aspergillus flavus, Aspergillus niger and Aspergillus fumigatus in the processes of UV/NH 2 Cl (2.0 mg/L) was 0.034, 0.030 and 0.061 cm2/mJ, respectively, which were higher than that of UV alone (0.027, 0.026 and 0.024 cm2/mJ) and UV/Cl 2 (0.023, 0.026 and 0.031 cm2/mJ). However, there was no synergistic effect for Aspergillus flavus and Aspergillus fumigatus. As for Aspergillus niger , the best synergistic effect can reach 1.86-log 10. This may be due to their different resistance to disinfectants, which were related to the size, an outer layer of rodlets (hydrophobins) and pigments. After UV/NH 2 Cl inactivation, the degree of cell membrane damage and intracellular reactive oxygen species were higher than that of UV alone. UV/NH 2 Cl had the advantages of high inactivation efficiency and inhibition of photoreactivation, which provides a new entry point for the disinfection of waterborne fungi. [Display omitted] [ABSTRACT FROM AUTHOR]

The performance of two conventional monochromatic ultraviolet-C (UV-C) low pressure mercury (LPM) sources (single and multiple lamps) was measured and compared with three emerging UV sources: a monochromatic KrCl* excimer lamp and UV-LEDs, and a polychromatic pulsed light (UV-C PL) lamp. Fluence-based kinetic parameters and electrical energy per order (E E0) of the UV sources was determined for the inactivation of E. coli bacteria, the reduction of deoxynivalenol (DON) mycotoxin, and F. graminearum spore growth to assess feasibility for various processing targets. The impact on E. coli photoreactivation and dark repair was also assessed. Each of the five UV sources excelled in certain applications while not being feasible for others. The UV-C PL lamp was the most effective for E. coli inactivation, requiring the lowest fluence of 1.4 mJ/cm2 for 5-log 10 reduction. The KrCl* excimer lamp was the most effective for preventing subsequent photoreactivation. The UV-LEDs and LPM lamp were equally effective for reducing fungal spore growth requiring 77.0 and 90.1 mJ/cm2 to achieve 90% reduction, respectively. The KrCl* excimer and UV-C PL lamps were the most effective at reducing DON contamination requiring 1250 and 500 mJ/cm2 to achieve 90% reduction, respectively. The evaluation of E E0 showed that the conventional LPM source with multiple lamps had approximately 2–3-fold better electrical efficiency for the reduction of all three tested targets due to its high wall plug efficiency compared to the next best UV-C PL lamp. This indicates that energy efficiency of emerging UV sources needs to be improved in further development. • Conventional and emerging UV lights were tested against bacteria, fungi and DON. • The phosphor pulsed light lamp showed superior inactivation efficacy of E. coli. • The pulsed light and excimer lamps were the most effective at reducing DON content. • The low pressure lamp and UV-LEDs excelled at inhibiting Fusarium growth. • The low pressure and pulsed light lamps were the most electrically efficient. [ABSTRACT FROM AUTHOR]

• UV222 suppressed photoreactivation of E. coli by 2-log compared with UV254. • UV222 disinfection damaged multiple cellular targets—DNA, protein, and the cell membrane. • UV222 induced DNA damage at fewer sites than UV254, but the damage was more severe. • UV222 damaged the E. coli cell membrane by photolyzing membrane lipid and protein. • UV222 photolyzed nucleic acid bases and amino acids. Low-pressure mercury lamps emitting at 254 nm (UV254) are used widely for disinfection. However, subsequent exposure to visible light results in photoreactivation of treated bacteria. This study employed a krypton chloride excimer lamp emitting at 222 nm (UV222) to inactivate E. coli. UV222 and UV254 treatment had similar E. coli -inactivation kinetics. Upon subsequent irradiation with visible light, E. coli inactivated by UV254 was reactivated from 2.71-log to 4.75-log, whereas E. coli inactivated by UV222 showed negligible photoreactivation. UV222 treatment irreversibly broke DNA strands in the bacterium, whereas UV254 treatment primarily formed nucleobase dimers. Additionally, UV222 treatment caused cell membrane damage, resulting in wizened, pitted cells and permeability changes. The damage to the cell membrane was mainly due to the photolysis of proteins and lipids by UV222. Furthermore, the photolysis of proteins by UV222 destroyed enzymes, which blocked photoreactivation and dark repair. The multiple damages can be further evidenced by 4.0–61.1 times higher quantum yield in the photolysis of nucleobases and amino acids for UV222 than UV254. This study demonstrates that UV222 treatment damages multiple sites in bacteria, leading to their inactivation. Employing UV222 treatment as an alternative to UV254 could be viable for inhibiting microorganism photoreactivation in water and wastewater. [Display omitted] [ABSTRACT FROM AUTHOR]

The Rad4-Rad23-Rad33 complex plays an essential anti-ultraviolet (UV) role depending on nucleotide excision repair (NER) in budding yeast but has been rarely studied in filamentous fungi, which possess two Rad4 paralogs (Rad4A/B) and orthologous Rad23 and rely on the photorepair of UV-induced DNA lesions, a distinct mechanism behind the photoreactivation of UV-impaired cells. Previously, nucleocytoplasmic shuttling Rad23 proved to be highly efficient in the photoreactivation of conidia inactivated by UVB, a major component of solar UV, due to its interaction with Phr2 in Beauveria bassiana, a wide-spectrum insect mycopathogen lacking Rad33. Here, either Rad4A or Rad4B was proven to localize exclusively in the nucleus and interact with Rad23, which was previously shown to interact with the white collar protein WC2 as a regulator of two photorepair-required photolyases (Phr1 and Phr2) in B. bassiana. The Δrad4A mutant lost ~80% of conidial UVB resistance and ~50% of activity in the photoreactivation of UVB-inactivated conidia by 5 h light exposure. Intriguingly, the reactivation rates of UVB-impaired conidia were observable only in the presence of rad4A after dark incubation exceeding 24 h, implicating extant, but infeasible, NER activity for Rad4A in the field where night (dark) time is too short. Aside from its strong anti-UVB role, Rad4A played no other role in B. bassiana’s lifecycle while Rad4B proved to be functionally redundant. Our findings uncover that the anti-UVB role of Rad4A depends on the photoreactivation activity ascribed to its interaction with Rad23 linked to WC2 and Phr2 and expands a molecular basis underlying filamentous fungal adaptation to solar UV irradiation on the Earth’s surface.

In Antarctic continent, the organisms are exposed to high ultraviolet (UV) radiation because of damaged stratospheric ozone. UV causes DNA lesions due to the accumulation of photoproducts. Photolyase can repair UV-damaged DNA in a light-dependent process by electron transfer mechanism. Here, we isolated a CPD photolyase gene PnPHR1 from Antarctic moss Pohlia nutans , which encodes a protein of theoretical molecular weight of 69.1 KDa. The expression level of PnPHR1 was increased by UV-B irradiation. Enzyme activity assay in vitro showed that PnPHR1 exhibited photoreactivation activity, which can repair CPD photoproducts in a light-dependent manner. The complementation assay of repair-deficient E. coli strain SY2 demonstrated that PnPHR1 gene enhanced the survival rate of SY2 strain after UV-B radiation. Additionally, overexpression of PnPHR1 enhanced the Arabidopsis resistance to UV-B radiation and salinity stress, which also conferred plant tolerance to oxidative stress by decreasing ROS production and increasing ROS clearance. Our work shows that PnPHR1 encodes an active CPD photolyase, which may participate in the adaptation of P. nutans to polar environments. [Display omitted] • PnPHR1 is a characterized CPD photolyase from moss species. • PnPHR1 repairs CPD photoproducts and exhibits photoreactivation activity in vitro. • PnPHR1 enhances the survival rate of a photorepair-deficient E. coli after UV-B. • PnPHR1 overexpression improves plant resistance to UV-B and salinity stresses. [ABSTRACT FROM AUTHOR]

Light provides critical information for the behavior and development of basically all organisms. Filamentous fungi sense blue light, mainly, through a unique transcription factor complex that activates its targets in a light-dependent manner. In Trichoderma atroviride , the BLR-1 and BLR-2 proteins constitute this complex, which triggers the light-dependent formation of asexual reproduction structures (conidia). We generated an ENVOY photoreceptor mutant and performed RNA-seq analyses in the mutants of this gene and in those of the BLR-1, CRY-1 and CRY-DASH photoreceptors in response to a pulse of low intensity blue light. Like in other filamentous fungi BLR-1 appears to play a central role in the regulation of blue-light responses. Phenotypic characterization of the Δ env -1 mutant showed that ENVOY functions as a growth and conidiation checkpoint, preventing exacerbated light responses. Similarly, we observed that CRY-1 and CRY-DASH contribute to the typical light-induced conidiation response. In the Δ env -1 mutant, we observed, at the transcriptomic level, a general induction of DNA metabolic processes and strong repression of central metabolism. An analysis of the expression level of DNA repair genes showed that they increase their expression in the absence of env -1. Consistently, photoreactivation experiments showed that Δ env -1 had increased DNA repair capacity. Our results indicate that light perception in T. atroviride is far more complex than originally thought. [ABSTRACT FROM AUTHOR]

Two gene of class II photolyases, PiPhr1 (1833 bp) and PiPhr2 (1809 bp), from the Antarctic diatom Phaeodactylum tricornutum ICE-H were cloned, the recombinant proteins expressed and purified. The molecular weight of the recombinant photolyases were determined to be 68 kDa with a pI of 9.04 and 68.82 with a pI of 7.31, respectively. Activity studies showed that both the recombinant enzymes were involved in the repair DNA damaged by UV light, that is they were most likely photolyases involved in photorepair of DNA. Further confirmation of this function was demonstrated by the increased expression of PiPhr1 and PiPhr2 after exposure to UV radiation, blue light and dark conditions by qRT-PCR. In summary, PiPhr1 and PiPhr2 were up regulated by UVB irradiation and blue light at 0.5 h and 3 h. Longtime (3 h) exposure to dark also increased the expression of PiPhr1 and PiPhr2. In vitro photoreactivation assays showed that PiPhr1 and PiPhr2 could repair CPDs utilizing blue light. This is the first time CPD Class II photolyase has been reported from Antarctic diatom. These results will add to the knowledge of the diatom CPF family and assist in understanding the functional role of these genes in Antarctic diatoms. [ABSTRACT FROM AUTHOR]

Light provides critical information for the behavior and development of basically all organisms. Filamentous fungi sense blue light, mainly, through a unique transcription factor complex that activates its targets in a light-dependent manner. In Trichoderma atroviride, the BLR-1 and BLR-2 proteins constitute this complex, which triggers the light-dependent formation of asexual reproduction structures (conidia). We generated an ENVOY photoreceptor mutant and performed RNA-seq analyses in the mutants of this gene and in those of the BLR-1, CRY-1 and CRY-DASH photoreceptors in response to a pulse of low intensity blue light. Like in other filamentous fungi BLR-1 appears to play a central role in the regulation of blue-light responses. Phenotypic characterization of the Δenv-1 mutant showed that ENVOY functions as a growth and conidiation checkpoint, preventing exacerbated light responses. Similarly, we observed that CRY-1 and CRY-DASH contribute to the typical light-induced conidiation response. In the Δenv-1 mutant, we observed, at the transcriptomic level, a general induction of DNA metabolic processes and strong repression of central metabolism. An analysis of the expression level of DNA repair genes showed that they increase their expression in the absence of env-1. Consistently, photoreactivation experiments showed that Δenv-1 had increased DNA repair capacity. Our results indicate that light perception in T. atroviride is far more complex than originally thought.

Beauveria bassiana serves as a main source of global fungal insecticides, which are based on the active ingredient of formulated conidia vulnerable to solar ultraviolet (UV) irradiation and restrained for all-weather application in green agriculture. The anti-UV proteins Rad1 and Rad10 are required for the nucleotide excision repair (NER) of UV-injured DNA in model yeast, but their anti-UV roles remain rarely exploredin filamentous fungi. Here, Rad1 and Rad10 orthologues that accumulated more in the nuclei than the cytoplasm of B. bassiana proved capable of reactivating UVB-impaired or UVB-inactivated conidia efficiently by 5h light exposure but incapable of doing so by 24 h dark incubation (NER) if the accumulated UVB irradiation was lethal. Each orthologue was found interacting with the other and two white collar proteins (WC1 and WC2), which proved to be regulators of two photolyases (Phr1 and Phr2) and individually more efficient in the photorepair of UVB-induced DNA lesions than either photolyase alone. The fungal photoreactivation activity was more or far more compromised when the protein–protein interactions were abolished in the absence of Rad1 or Rad10 than when either Phr1 or Phr2 lost function. The detected protein–protein interactions suggest direct links of either Rad1 or Rad10 to two photolyase regulators. In B. bassiana, therefore, Rad1 and Rad10 tied to the photolyase regulators have high activities in the photoprotection of formulated conidia from solar UV damage but insufficient NER activities in the field, where night (dark) time is too short, and no other roles in the fungal lifecycle in vitro and in vivo.

In their 2019 study, Molina et al. evaluate a cell proliferation assay that fluorescently quantifies DNA for assessing ballast water treatment efficacy of organisms = 10 to 50 µm. Because of concerns with the overall experimental design, procedures, and authors' interpretations, their conclusions do not appear to be justified and the assay used to arrive at those conclusions is not proven appropriate. Specific concerns we highlight include UV and chlorine dose calculations and exposure conditions, bacterial contamination issues, poor agreement between controls, high detection limit of the assay, and mismatch between conclusions in the abstract and statistical significance of the data. Their conclusions that "population maintenance or growth was evident ... after UV treatment" and "photoreactivation could have been attributed to increased mean DNA concentrations" are therefore not scientifically defensible without further experimentation and verification. These concerns call into serious question the use of this study by the US Coast Guard or other governing bodies to (1) determine the applicability of this cell proliferation assay for assessing ballast water disinfection or (2) make conclusions regarding the suitability of UV treatment for inactivating organisms in ballast water. [ABSTRACT FROM AUTHOR]

Under natural conditions, plants are exposed to solar ultraviolet (UV) radiation, which damages chromosomal DNA. Although plant responses to UV-induced DNA damage have recently been elucidated in detail, revealing a set of DNA repair mechanisms and translesion synthesis (TLS), limited information is currently available on UV-induced mutations in plants. We previously reported the development of a supF -based system for the detection of a broad spectrum of mutations in the chromosomal DNA of Arabidopsis. In the present study, we used this system to investigate UV-induced mutations in plants. The irradiation of supF -transgenic plants with UV-C (500 and 1000 J/m2) significantly increased mutation frequencies (26- and 45-fold, respectively). G:C to A:T transitions (43–67% of base substitutions) dominated in the mutation spectrum and were distributed throughout single, tandem, and multiple base substitutions. Most of these mutations became undetectable with the subsequent illumination of UV-irradiated plants with white light for photoreactivation (PR). These results indicated that not only G:C to A:T single base substitutions, but also tandem and multiple base substitutions were caused by two major UV-induced photoproducts, cyclobutane-type pyrimidine dimers (CPDs) and pyrimidine (6-4) pyrimidone photoproducts (6-4 PPs). In contrast, a high proportion of A:T to T:A transversions (56% of base substitutions) was a characteristic feature of the mutation spectrum obtained from photoreactivated plants. These results define the presence of the characteristic feature of UV-induced mutations, and provide insights into DNA repair mechanisms in plants. • The supF system was used for the analysis of UV-induced mutations in plants. • The irradiation of supF -transgenic plants with UV-C increased mutation frequencies. • G:C to A:T transitions dominated in the mutation spectrum of base substitutions. • Most of the UV-induced mutations became undetectable by photoreactivation. • High proportion of A:T to T:A is a distinctive feature in photoreactivated plants. [ABSTRACT FROM AUTHOR]

Many plant-dwelling mites reside on lower leaf surfaces. The biological impact of solar ultraviolet-B (UV-B) radiation on spider mites has been demonstrated over the last decade. Due to the serious problem of acaricide resistance in spider mites, the development of alternative control methods and establishment of an integrated pest management (IPM) strategy are urgently needed, especially for greenhouse horticultural crops such as strawberries. A physical control method for spider mites using UV-B lamps (UV-B method) has been established. Using the UV-B method, simultaneous control of spider mites and powdery mildew, a major disease, is possible, making it is a favorable IPM strategy. Here, I introduce general findings regarding the biological impact of UV radiation on spider mites and phytoseiid mites, useful natural enemies for biological control, over the last decade, including dose response, effective wavelengths, and photoreactivation. Moreover, I introduce the application of UV-B to spider mite control in strawberry greenhouses, including the possibility of concurrent use with biological control via phytoseiid mites, and discuss its possible contributions to IPM. [ABSTRACT FROM AUTHOR]

Microwave discharge electrodeless lamp (MDEL) is a novel ultraviolet (UV) light source. Synergistic disinfection using UV light emitted by MDEL (MWUV) coupled with ozone (O 3) at an ultra-low dose was investigated. Escherichia coli and Bacillus subtilis were deactivated more effectively by MWUV/O 3 than by either MWUV or O 3 alone. MWUV/O 3 treatment using an O 3 concentration of 0.4 mg/L gave an E. coli inactivation rate of 5.52 log. The photoreactivation degree and rate of E. coli were lower after inactivation by MWUV/O 3 treatment than after MWUV treatment alone. The maximum photoreactivation rates after the MWUV/O 3 and MWUV treatments were 2.90% and 16.08%, respectively. MWUV/O 3 disinfection also inhibited dark resurrection of E. coli and gave a maximum dark resurrection rate of 0.0036%. Electron paramagnetic resonance spectroscopy indicated that more hydroxyl radicals were generated during MWUV/O 3 treatment. Scanning electron microscopy and laser confocal scanning microscopy observations indicated that O 3 played a key role in breaking down the cell structure. MWUV/O 3 treatment gave a good disinfection effect on fecal coliform bacteria in actual domestic wastewater. The results indicated that inactivation of bacteria can be more effectively achieved by MWUV treatment with O 3. [Display omitted] • Inactivation of bacteria by MWUV can be enhanced by an ultra-low concentration O 3. • MWUV/O 3 inhibited the photoreactivation and dark resurrection of bacteria. • MWUV/O 3 generated more HO·and accelerated the cell structure destruction. • MWUV/O 3 has a good disinfection effect on fecal coliform in actual wastewater. [ABSTRACT FROM AUTHOR]

Anti-ultraviolet (UV) roles of Rad2 and Rad14 depend on nucleotide excision repair (NER) of UV-induced DNA lesions in budding yeast but remain unexplored yet in filamentous fungi. Here, nucleus-specific Rad2 and Rad14 orthologs are shown to recover Beauveria bassiana , a main source of wide-spectrum mycoinsecticides, from solar UV damage through photorepair-depending photoreactivation. As a photorepair index, photoreactivation (germination) rates of lethal UVB dose-irradiated conidia via a 3- or 5-h light plus 9- or 7-h dark incubation at 25 °C were drastically reduced in the Δ rad2 and Δ rad14 mutants versus a wild-type strain. As an NER index, nighttime-mimicking 12-h dark reactivation rates of low UVB dose-impaired conidia decreased sharply compared to the corresponding photoreactivation rates in the presence or absence of either ortholog, indicating that its extant NER activity was limited to recovering light UVB damage in the field. The high photoreactivation activity of either Rad2 or Rad14 was derived from its tight link to a large protein complex formed by photolyase regulators and other anti-UV proteins through multiple protein-protein interactions revealed by yeast two-hybrid assays. Therefore, Rad2 and Rad14 recover B. bassiana from solar UV damage through photoreactiovation in vivo that depends primarily on photorepair, although they contribute little to the fungal lifecycle-related phenotypes. These findings unveil a novel scenario distinguished from the NER-depending anti-UV roles of Rad2 and Rad14 in the model yeast and broaden a biological basis crucial for rational application of fungal insecticides to improve pest control efficacy via feasible recovery of solar UV damage. [Display omitted] • Anti-UV roles of yeast Rad2 and Rad14 rely on nucleotide excision repair (NER). • Rad2 and Rad4 orthologs have hardly feasible NER activities in B. bassiana. • Both of them have high activities in photoreactivation of UVB-inactivated conidia. • Both of them are linked to DNA photorepair-reliant photolyase regulators. • The high activities are vital for improved application of B. bassiana insecticides. [ABSTRACT FROM AUTHOR]

The use of light to promote health, reduce harm, and restore functionality is a novel, non-accumulative physical strategy that contrasts with the predominantly chemical approaches used in Western medicine. This strategy may serve as an independent function for healthcare professionals and warrants further exploration. Photoreactivation, achieved by adjusting patients' physiological clocks at different times, utilizing specific wavelengths, varying color temperatures, and using illuminance, is a potent tool for improving mood and sleep quality, regulating autonomic nervous system balance, enhancing attention, and delaying cognitive decline. Light therapy is a rapidly expanding field in healthcare that offers new opportunities to enhance quality of life, prevent diseases, and improve overall well-being. This article elucidates the fundamental concepts of photoreactivation, explores its application across diverse health domains, examines its future development prospects, and discusses the challenges faced by photoreactivation and related solutions to ensure the responsible use of light to enhance and restore physiological and psychological functions.

Photoreactivation is a mechanism in which photolyase directly repairs either cyclobutane pyrimidine dimers (CPDs) or (6-4) photoproducts [(6-4) PPs] caused by ultraviolet (UV) light. In the filamentous fungus Neurospora crassa, some UVsensitive mutants such as mus-44 have been reported to exhibit a partial photoreactivation defect (PPD) phenotype, but its mechanism has not been elucidated for a long time. In this study, the N. crassa CPD photolyase PHR was overexpressed in the Δmus-44 strain, but photoreactivation ability was not increased. Furthermore, Escherichia coli CPD photolyase or Arabidopsis thaliana (6-4) PP photolyase was also introduced into Δmus-44; however, the PPD phenotype was not complemented. These results suggested that the PPD phenotype in N. crassa is not caused by residual unrepaired pyrimidine dimers, which are the main type of DNA damage caused by UV irradiation. Finally, we revealed that Δmus-44, but not the Δmus-43 strain, which does not show the PPD phenotype, displayed higher sensitivity with increasing dose rate of UV. Moreover, Δmus-44 was also sensitive to an interstrand crosslinking agent. This indicates that the high dose of UV in our experimental condition induces DNA damage other than pyrimidine dimers, and that such damage is a likely cause of the PPD phenotype. [ABSTRACT FROM AUTHOR]

RAD23 can repair yeast DNA lesions through nucleotide excision repair (NER), a mechanism that is dependent on proteasome activity and ubiquitin chains but different from photolyase-depending photorepair of UV-induced DNA damages. However, this accessory NER protein remains functionally unknown in filamentous fungi. In this study, orthologous RAD23 in Beauveria bassiana, an insectpathogenic fungus that is a main source of fungal insecticides, was found to interact with the photolyase PHR2, enabling repair of DNA lesions by degradation of UVBinduced cytotoxic (6-4)-pyrimidine-pyrimidine photoproducts under visible light, and it hence plays an essential role in the photoreactivation of UVB-inactivated conidia but no role in reactivation of such conidia through NER in dark conditions. Fluorescence-labeled RAD23 was shown to normally localize in the cytoplasm, to migrate to vacuoles in the absence of carbon, nitrogen, or both, and to enter nuclei under various stresses, which include UVB, a harmful wavelength of sunlight. Deletion of the rad23 gene resulted in an 84% decrease in conidial UVB resistance, a 95% reduction in photoreactivation rate of UVB-inactivated conidia, and a drastic repression of phr2. A yeast two-hybrid assay revealed a positive RAD23-PHR2 interaction. Overexpression of phr2 in the Δrad23 mutant largely mitigated the severe defect of the Δrad23 mutant in photoreactivation. Also, the deletion mutant was severely compromised in radial growth, conidiation, conidial quality, virulence, multiple stress tolerance, and transcriptional expression of many phenotype-related genes. These findings unveil not only the pleiotropic effects of RAD23 in B. bassiana but also a novel RAD23-PHR2 interaction that is essential for the photoprotection of filamentous fungal cells from UVB damage. IMPORTANCE RAD23 is able to repair yeast DNA lesions through nucleotide excision in full darkness, a mechanism distinct from photolyase-dependent photorepair of UV-induced DNA damage but functionally unknown in filamentous fungi. Our study unveils that the RAD23 ortholog in a filamentous fungal insect pathogen varies in subcellular localization according to external cues, interacts with a photolyase required for photorepair of cytotoxic (6-4)-pyrimidine-pyrimidine photoproducts in UV-induced DNA lesions, and plays an essential role in conidial UVB resistance and reactivation of UVB-inactivated conidia under visible light rather than in the dark, as required for nucleotide excision repair. Loss-of-function mutations of RAD23 exert pleiotropic effects on radial growth, aerial conidiation, multiple stress responses, virulence, virulence-related cellular events, and phenotype-related gene expression. These findings highlight a novel mechanism underlying the photoreactivation of UVB-impaired fungal cells by RAD23 interacting with the photolyase, as well as its essentiality for filamentous fungal life. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effect of riboflavin supplementation of culture medium on conidial UV-A tolerance of M. acridum (Driver & Milner) (Hypocreales: Clavicipitaceae) and M. robertsii (Bischoff, Rehner & Humber) (Hypocreales: Clavicipitaceae). These fungi were produced on culture medium supplemented, or not supplemented, with riboflavin. Relative germination and expression patterns of some photoprotection-related genes were evaluated after irradiating with artificial UV-A, or with filtered solar radiation (> 320 nm; UV-A and visible radiation). M. acridum conidia harvested from riboflavin-supplemented culture medium demonstrated enhanced UV-A tolerance when irradiated with artificial UV-A. Nevertheless, relative germination of conidia of both species produced on riboflavin-supplemented medium and exposed to filtered solar radiation was significantly higher than those produced on medium not supplemented with riboflavin. Riboflavin increased the transcription of photolyases, laccases and polyketide synthase genes. However, each fungal species induced different genes patterns involved in DNA repair and photoprotection. The addition of riboflavin to the substrate used for mass production of Metarhizium spp. and the resulting enhancement of conidial tolerance to solar radiation may improve the effectiveness of these fungi in biological control programs. [ABSTRACT FROM AUTHOR]

The depletion of the stratospheric ozone layer is a major environmental issue and has increased the dosage of ultraviolet-B (UV-B) radiation reaching the Earth’s surface. Organisms are negatively affected by enhanced UV-B radiation, and especially in crop plants this may lead to severe yield losses. Soybean (Glycine max L.), a major legume crop, is sensitive to UV-B radiation, and therefore, it is required to breed the UV-B-resistant soybean cultivar. In this study, 688 soybean germplasms were phenotyped for two categories, Damage of Leaf Chlorosis (DLC) and Damage of Leaf Shape (DLS), after supplementary UV-B irradiation for 14 days. About 5% of the germplasms showed strong UV-B resistance, and GCS731 was the most resistant genotype. Their phenotypic distributions showed similar patterns to the normal, suggesting UV-B resistance as a quantitative trait governed by polygenes. A total of 688 soybean germplasms were genotyped using the Axiom® Soya 180K SNP array, and a genome-wide association study (GWAS) was conducted to identify SNPs significantly associated with the two traits, DLC and DLS. Five peaks on chromosomes 2, 6, 10, and 11 were significantly associated with either DLC or DLS, and the five adjacent genes were selected as candidate genes responsible for UV-B resistance. Among those candidate genes, Glyma.02g017500 and Glyma.06g103200 encode cryptochrome (CRY) and cryptochrome 1 (CRY1), respectively, and are known to play a role in DNA repair during photoreactivation. Real-time quantitative RT-PCR (qRT-PCR) results revealed that CRY1 was expressed significantly higher in the UV-B-resistant soybean compared to the susceptible soybean after 6 h of UV-B irradiation. This study is the first GWAS report on UV-B resistance in soybean, and the results will provide valuable information for breeding UV-B-resistant soybeans in preparation for climate change.

Photoreactivation is a direct process of repairing a damaged DNA with the help of ultraviolet in the range of 320-370 nm. Research is designed to acknowledge the effect of time exposure and UV vis ray’s intensity to numbers of Coliforms and E.coli. The results prove the effect of UV exposure time on the increase of coliform which is 60,2% (p-value=0,0001). The increase of coliform happens after 180th minutes of exposure. But, in this research there is no effect of UV’s intensity towards both numbers of coliform (p-value = 0,152) and E.Coli (p-value=0,578). Besides buying a refilled mineral water from a water depot whose disinfecting with UV ray and ozone combined, closing the gallon of mineral water since the first day being used to avoid being exposed by UV vis ray from the sun is a must-do to avoid photoreactivation process.