High Ultraviolet Radiation Research Articles

Durable colorful superhydrophobic cotton fabric constructed from modified microcrystalline cellulose prepared by Schiff base reaction

Cotton fabric is widely used for its excellent wearability but often suffers from drawbacks such as poor stain resistance, susceptibility to corrosion, and low colorfastness. Here, we introduce a novel method to create colorful superhydrophobic cotton fabric using octadecylamine-modified dialdehyde cellulose (DAC/ODA) particles as building units, which are synthesized via a Schiff base reaction and subsequently dyed with active dyes. Leveraging the film-forming ability of ODA and the affinity between cellulose materials, DAC/ODA formed a robust coating on the cotton surface, with its microstructure precisely controlled through thermal induction. The resulting fabric (DAC/ODA/Cotton) exhibited exceptional superhydrophobicity, with a water contact angle of 155° and an osmotic pressure of 426.2 mm. The uniform coverage of DAC/ODA on cotton fibers also ensured high air permeability (33.1 mm/s). Additionally, DAC/ODA/Cotton demonstrated outstanding antifouling performance against various common liquids and water can easily remove dust from its surface. Importantly, the fabric maintains its superhydrophobicity under extreme conditions such as high temperature, UV radiation, and acid-base exposure. Even after 100 abrasion cycles, no significant changes in surface morphology and color on DAC/ODA/Cotton were observed. This fluorine-free, environmentally friendly approach offers significant potential for developing multifunctional textiles and coatings with broad applications while reducing environmental impact.

Older Amphibian Larvae Are More Sensitive to Ultraviolet Radiation and Experience More Sublethal Carryover Effects Post-Metamorphosis.

Elevated ultraviolet radiation (UVR) is postulated as one of multiple, interrelated environmental stressors driving amphibian population declines globally. However, key knowledge gaps remain in elucidating the link between elevated UVR and amphibian declines in a changing climate, including whether timing and irradiance of UVR exposure in early life dictates the onset of detrimental carryover effects post-metamorphosis. In this study, striped marsh frog larvae (Limnodynastes peronii) were exposed to UVR at one of two different irradiances for up to 7 days, either as hatchlings (Gosner stage 23) or as older larvae (Gosner stage 25-28). These animals were then reared to metamorphosis in the absence of UVR to examine independent and interactive carryover effects throughout development. Older larvae were more sensitive to UVR than hatchlings, with 53.1% and 15.6% mortality in larvae exposed to high and low irradiance respectively, compared with no mortality of hatchlings in either irradiance treatment. Irradiance and timing of UVR exposure had interactive effects on larval body length, causing stunted growth patterns and a lack of compensatory growth following UVR exposure, particularly in animals exposed to high irradiance UVR later in development. Timing of UVR exposure also determined the severity of carryover effects into metamorphosis, including delayed metamorphosis and the first published account (to our knowledge) of latent UVR-induced depigmentation in an amphibian. These findings highlight how acute changes to the larval UVR exposure regime can impact on amphibian health later in life, with implications for our understanding of the effects of climate change on UVR-related amphibian declines.

Skin cancer prevention: a systematic review of the efficacy of clinical trial-based interventions

Skin cancer is one of the most common malignancies and its incidence continues to increase worldwide, especially in areas of high ultraviolet (UV) radiation. This systematic review highlights that an effective preventive approach combines sun protection, education, and workplace policies. Advanced sunscreens with DNA repair complexes are useful in reducing precursor lesions such as actinic keratosis. The implementation of workplace policies that provide protective equipment and create shaded areas is especially effective for outdoor workers. Educational programs in schools and on-the-job training encourage sun protection practices from childhood and in work settings, although their effectiveness depends on demographic and cultural factors. It is recommended to tailor interventions to each population and explore their long-term sustainability, as well as to evaluate the economic impact of these policies to achieve effective skin cancer prevention.

Metabolomic Analysis of Elymus sibiricus Exposed to UV-B Radiation Stress.

Plants cultivated on the Qinghai-Tibet Plateau (QTP) are exposed to high ultraviolet radiation intensities, so they require effective mechanisms to adapt to these stress conditions. UV-B radiation is an abiotic stress factor that affects plant growth, development, and environmental adaptation. Elymus sibiricus is a common species in the alpine meadows of the QTP, with high-stress resistance, large biomass, and high nutritional value. This species plays an important role in establishing artificial grasslands and improving degraded grasslands. In this study, UV-B radiation-tolerant and UV-B radiation-sensitive E. sibiricus genotypes were subjected to simulated short-term (5 days, 10 days) and long-term (15 days, 20 days) UV-B radiation stress and the metabolite profiles evaluated to explore the mechanism underlying UV-B radiation resistance in E. sibiricus. A total of 699 metabolites were identified, including 11 primary metabolites such as lipids and lipid-like molecules, phenylpropanoids and polyketides, organic acids and their derivatives, and organic oxygen compounds. Principal component analysis distinctly clustered the samples according to the cultivar, indicating that the two genotypes exhibit distinct response mechanisms to UV-B radiation stress. The results showed that 14 metabolites, including linoleic acid, LPC 18:2, xanthosine, and 23 metabolites, including 2-one heptamethoxyflavone, glycyrrhizin, and caffeic acid were differentially expressed under short-term and long-term UV-B radiation stress, respectively. Therefore, these compounds are potential biomarkers for evaluating E. sibiricus response to UV-B radiation stress. Allantoin specific and consistent expression was up-regulated in the UV-B radiation-tolerant genotype, thereby it can be used to identify varieties resistant to UV-B radiation. Different metabolic profiles and UV-B radiation response mechanisms were observed between the UV-B radiation-tolerant and UV-B radiation-sensitive E. sibiricus genotypes. A model for the metabolic pathways and metabolic profiles was constructed for the two genotypes. This metabolomic study on the E. sibiricus response to UV-B radiation stress provides a reference for the breeding of new UV-B radiation-tolerant E. sibiricus cultivars.

Superhydrophobic Coating Based on Nano-Silica Modification for Antifog Application of Partition Glass

In this study, vinyl triethoxysilane (VTES), KH-560 and trimethylchlorosilane (TMCS) were used to modify the surface groups of commercially available nano-silica (SiO2, 50 nm), and ethylene vinyl acetate copolymer (EVA) was used as a film-forming agent. EVA/SiO2, EVA/V-SiO2, EVA/K-SiO2 and EVA/T-SiO2 coatings were prepared, respectively. The coatings were characterized by SEM, FTIR, TG and contact angle. It was found that when the mass percentage of SiO2 was 66 wt%, the hydrophobicity performance of the coating could be significantly improved by silica modification. Compared to the EVA/SiO2, the water contact angle (WCA) of the EVA/V-SiO2, EVA/K-SiO2 and EVA/T-SiO2 were increased by 24.0%, 14.4% and 24.6%, respectively. The FTIR results indicated that VTES, KH-560 and TMCS could effectively replace the -OH groups on the surface of the SiO2 after hydrolysis, resulting in the presence of water transport groups on the SiO2 surface. The TG results certified that TMCS had the highest substitution rate (24.6%) for the -OH groups on the SiO2 surface after the hydrolysis. Additionally, the SEM results indicated that T-SiO2 was more easily dispersed in the EVA film-forming agent, leading to a uniform micro–nano surface rough structure, which aligned with the Cassie–Wenzel model. The durability test had demonstrated that the EVA/T-SiO2 maintained its hydrophobic properties even after enduring 40,000 drops of water and the impact of 200 g of sand. Furthermore, it exhibited excellent resistance to acid corrosion, along with superior self-cleaning properties and an anti-fog performance. It also provided outstanding protection against high temperatures and UV radiation for outdoor applications.

An experimental study of the biological impact of a superflare on the TRAPPIST-1 planets

ABSTRACT In this study, we conducted experiments to assess the biological effects of high fluences of UV radiation (UVR) on the TRAPPIST-1 planetary system (planets e, f, g within the habitable zone), unlike previous estimates made by other authors which used theoretical approaches. To this end, we first calculated the UV fluxes at the orbits of the planets of the TRAPPIST-1 system during quiescent conditions and during a superflare. We then studied the effects of UVR on microbial life by exposing UV-tolerant (Deinococcus radiodurans) and UV-susceptible bacteria (Escherichia coli) to fluences equivalent to a superflare on the unshielded surface of these planets. Based on the results of our laboratory experiments, we have found a survival fraction of $6.31\times 10^{-8}$ for D. radiodurans and a survival fraction below the limit of detection for E. coli at the surface of the planet e, which would receive the highest UVR flux. These survival fractions were higher for the planets f and g. In contrast to the results obtained by other authors which used theoretical estimates, we show that a fraction of the population of microorganisms could tolerate the high UVR fluences of a superflare on the surface of TRAPPIST-1 planets, even without any shielding such as that provided by an atmosphere or an ocean. Our study evidences the existence of methodological problems in theoretical approaches. It also emphasizes the importance of performing specifically designed biological experiments to predict microbial survival in extraterrestrial contexts.

Environmental characterization and impact of climatic fluctuations on the diversity of extremophilic bacterial communities of a high-altitude seasonal meltwater pond on Ojos del Salado (Dry Andes, Chile)

Earth has unique environments where only microorganisms adapted to extreme conditions can survive. The focus of this study was a high-altitude seasonal meltwater pond on the Altiplano plateau at 5900 m (Dry Andes). The polyextremophilic bacteria of this habitat must adapt to a range of extremities, including cold and dry climate, high UV radiation, and low nutrient availability. A macro-scale analysis was performed to characterize the environment using satellite imagery. To study the composition of bacterial communities, samples were taken from permafrost, water, and sediment of a meltwater pond during three subsequent expedition years under different weather conditions (average, high precipitation, severe drought). The bacterial diversity of the samples was revealed by Illumina MiSeq 16S rRNA gene amplicon sequencing. The results showed that the relative abundance of dominant phyla, such as Pseudomonadota, Bacteroidota, Acidobacteriota, and Verrucomicrobiota varied according to sample types and weather conditions, supported by the satellite environmental state analysis that showed correlations between the availability of snow, water surfaces, and the corresponding surface temperature values. Strong moisture-dependent quantitative changes were detected in the phyla Cyanobacteriota and Actinomycetota. Predominant sequences were linked to orders Chitinophagales, Burkholderiales, Flavobacteriales, and Sphingomonadales, known for their ability to degrade various organic compounds.

Temperature and ultraviolet radiation on a high mountain daphnid: When do interactions become lethal to highly adapted populations?

ABSTRACT Aquatic organisms from high mountain lakes experience extreme influences of climate and solar radiation, especially ultraviolet radiation (UVR), manifested through alterations in physiology, life history, and phenology. Zooplankton, a pivotal component of lake ecosystems, is particularly sensitive to changes in environmental conditions because of their short life cycles and diminished mobility. In the high mountains of the tropical Andes, zooplankton populations are adapted to low temperatures and high UVR because most of the Andean lakes are >4000 m a.s.l. This study focuses on Daphnia pulicaria populations originating from high-mountain Andean lakes, investigating their responses to different temperatures and UVR exposure by means of lab experiments. Key findings indicate that temperature is the most important factor impacting population variables, with high temperatures and UVR exposure leading to unfavorable population outcomes; however, physiological variables (cell viability and pigmentation, measured as melanin) are similarly influenced by temperature and UVR exposure. Pigmentation increases with temperature and is accentuated by solar radiation, indicating an adaptive response to mitigate UVR damage. Conversely, cellular viability declines with elevated temperatures and UVR exposure, showing that higher temperatures may offset the protective effects of pigmentation. Overall, these findings underscore the vulnerability of daphnid populations in high-mountain Andean systems to anticipated climate change impacts, with potential consequences for ecological dynamics in these critical ecosystems. More importantly, they show the importance of studying temperature and UVR (and probably other environmental conditions) as interacting variables because the results will dramatically differ if each factor is considered separately.

A 10 km daily-level ultraviolet-radiation-predicting dataset based on machine learning models in China from 2005 to 2020

Abstract. Ultraviolet (UV) radiation is closely related to health; however, limited measurements have hindered further investigation of its health effects in China. Machine learning algorithms have been widely used to predict environmental factors with high accuracy, but a limited number of studies have implemented it for UV radiation. The main aim of this study is to develop a UV radiation prediction model using the random forest approach and predict the UV radiation with a daily and 10 km resolution in mainland China from 2005 to 2020. The model was developed with multiple predictors, such as UV radiation data from satellites as independent variables and ground UV radiation measurements from monitoring stations as the dependent variable. Missing satellite-based UV radiation data were obtained using the 3 d moving average method. The model performance was evaluated using multiple cross-validation (CV) methods. The overall R2 and root mean square error between measured and predicted UV radiation from model development and model 10-fold CV were 0.97 and 15.64 W m−2 and 0.83 and 37.44 W m−2 at the daily level, respectively. The model that incorporated erythemal daily dose (EDD) retrieved from the Ozone Monitoring Instrument (OMI) had a higher prediction accuracy than that without it. Based on predictions of UV radiation at the daily level, 10 km spatial resolution, and nearly 100 % spatiotemporal coverage, we found that UV radiation increased by 4.20 %, PM2.5 levels decreased by 48.51 %, and O3 levels increased by 22.70 % from 2013–2020, suggesting a potential correlation among these environmental factors. The uneven spatial distribution of UV radiation was associated with factors such as latitude, elevation, meteorological factors, and season. The eastern areas of China pose a higher risk due to both high population density and high UV radiation intensity. Using a machine learning algorithm, this study generated a gridded UV radiation dataset with extensive spatiotemporal coverage, which can be utilized for future health-related research. This dataset is freely available at https://doi.org/10.5281/zenodo.10884591 (Jiang et al., 2024).

Does pigmentation provide protection to bdelloid rotifers in a high ultraviolet B environment?

AbstractAquatic species found in habitats with limited shade and little dissolved organic carbon (DOC) have increased vulnerability to ultraviolet radiation (UVR) damage. Pigmentation is a common mechanism used by animals for protection from UVR. A pigmented bdelloid rotifer, Philodina, occurs in high densities in shallow rock pools in El Paso Co., TX, and is subject to repeated desiccation and high UVR. To understand the roles of DOC, pigmentation, and dormancy in reducing the effects of UVR exposure in these rotifers: (1) DOC levels in rock pools were measured before and after the summer monsoon season and (2) hydrated or dormant bdelloids (desiccated for 0, 1, 7, or 32 d) that differed in degree of pigmentation (highly, moderately, lightly, and none) were exposed to three intensities of UVB radiation (low, mid, or high) and monitored for survival after 48 h. Pigmented bdelloids were found in rock pools with lower DOC concentrations. Logistic regression analysis indicated that pigmentation level, desiccation time, and UVB intensity all affected survival. Bdelloids in the dormant form for 1 d were more resistant to UVB exposure at all pigmentation levels. However, as desiccation time increased, the odds of surviving decreased. Hydrated highly pigmented bdelloids were three times more likely to survive desiccation, UVB radiation, and their combined effects. Prolonged periods of drought due to the changing climate will alter DOC concentrations, causing photoprotection to become an increasingly important survival strategy for aquatic invertebrates, especially those inhabiting shallow waters.

Characterization of Bacterial Isolates from Freshwater Environments in Livingstone Island, Antarctica, Using Cultivation and Molecular Methods

The present research work summarizes the investigation of the microbial characteristics of bacterial isolates obtained from freshwater samples collected at various points throughout the Bulgarian Antarctic base “St. Kliment Ohridski” on Livingstone Island. The ability of microorganisms in psychrophilic envi¬ronments to survive and reproduce at low temperatures, lack of nutrients, and high UV radiation, suggests that they have developed specific mechanisms to overcome these extreme conditions. To understand the range of influence of these environmental factors standard microbiological techniques were used. The re¬search provides data on the influence of UV light, temperature range, determination of minimum inhibitory concentration (MIC) to different heavy metals, and 16S rDNA taxonomic identification of the isolates. Ant¬arctic microorganisms are of great interest in food, textile, and brewing industries, production of detergents, etc. The microbial composition in such hostile habitats still little affected by the anthropogenic factor is es¬sential for understanding the potential of psychrophilic microorganisms in different practical applications.

Variations in polyphenol content and anthocyanin composition in bilberry populations (Vaccinium myrtillus L.) due to environmental factors

Anthocyanins are natural pigments belonging to the flavonoid group, subclasses of polyphenol compounds. Bilberry (Vaccinium myrtillus L.) is a commercially important wild berry species, which accumulates high quantities of polyphenols, especially anthocyanins in the skin and flesh. This research aimed to evaluate the total anthocyanins content (TA) and anthocyanin composition profile of fruits in thirty wild bilberry populations from five regions of northern Montenegro. Total anthocyanin content in examined wild bilberries ranged from 236 to 656 mg/100 g. Delphinidin was found to be the most abundant aglycone, followed by cyanidin. Regions at higher altitudes (1129–1699 m) and with high UV radiation (0.370–0.480 W/m²) had higher values of anthocyanins. There were significant variations in anthocyanin content within and between the populations, indicating differences in berry raw material. Variations in the anthocyanin content expressed in different bilberry populations from various regions are a result of the cumulative effects of genotype and environment.

Arsenic, selenium, and mercury speciation in hypersaline lakes of the Andean Altiplano: Link between extreme levels and biodiversity repartition

Arsenic (As) and mercury (Hg) are highly toxic contaminants whereas selenium (Se) is both an essential trace element and potentially harmful at higher concentrations. The hyper-saline lakes of southern Bolivian Altiplano, which are ecological niches for endemic species, are also expected to be enriched in these toxic trace elements. The biogeochemistry of As, Hg, and Se in such high-altitude extreme environments (e.g., high UV radiation and salt content) remains poorly understood. In this study, we investigated the concentrations and chemical forms (speciation) of As, Hg, and Se in sediment, water, and air samples of Lagunas Colorada (LC), Verde (LV), and Blanca (LB) in the South Lipez region (>4200 m a.s.l.). We compared them with the repartition of biodiversity (invertebrates, algae, and bacteria). Extreme As concentrations were found in water (up to 82 mg L−1), and the main As species was inorganic As(V), with neither biogenic methylated As nor volatile As forms being detected in water and air, respectively. Se concentrations in water were of 0.1 to 1.4 μg L−1, and Se existed under different redox states, i.e., Se(IV), Se(VI), and reduced Se (0, -II), including biogenic methylated Se(-II) (trimethyl selenonium). Volatile Se compounds (e.g., dimethyl selenide) were detected in water and air samples. Hg was enriched in the surface water (6 to 30 ng L−1) compared to other regional water bodies, and a significant amount of methyl-Hg and gaseous Hg(0) was detected. The drastic disparity between As, Se and Hg concentrations and speciation between lakes has important implications for their cycling in these extreme aquatic systems. While As mostly accumulated in its oxidized and non-volatile form, Hg and Se concentrations can be controlled by significant conversion to reduced and methylated forms, allowing efficient evasion to the atmosphere. Finally, the salinity, including major ions, and high levels of As were among the main drivers of biodiversity repartition between lakes.

Enhanced Marangoni flow to fabricate uniform and porous SiO2 films: Toward superior high transparency, antifogging, and self- cleaning properties

Fogging on transparent substrate greatly impacts transmittance, causing inconvenience and potential hazards. Increasing surface roughness to enhance hydrophilicity often reduces transmittance. Here, by enhancing the Marangoni flow to inhibit the coffee-ring effect during SiO2 droplet drying, we propose for the first time to manufacture superhydrophilic and high-transmittance coatings with porous structures on various substrates, including glass and resin. This approach relies on a simple, potentially large-scale ultrasonic spray method to enhance the Marangoni flow of SiO2 dispersion with different particle sizes by adding multiple surfactants to reduce the surface tension of the dispersion. The water contact angle of the SiO2 film decreases to below 5° within 0.5 s, imparting anti-fogging properties to the substrate. The film exhibits a transmittance of 93.1 % at 580 nm, surpassing the inherent 90.8 % transmittance of the bare glass. Notably, the film shows remarkable self-cleaning properties due to potent hydration from eco-friendly SiO2 nanoparticles and the porous structure. Owing to the hydrogen bonding between tightly packed small-sized SiO2 particles as well as between the particles and substrate, the surface morphology of the film on glass remains intact even after washing, and soaking. The porous SiO2 film, with a contact angle dropping to below 5° within 0.5 s, maintains its superhydrophilicity even after being exposed to high temperatures, UV irradiation, and humidity conditions. The simple production process of the porous SiO2 films offers a promising method for preparing high-transmittance anti-fogging films with significant industrial potential.

The copepod Acartia spinicauda feeds less and dies more under the influences of solar ultraviolet radiation and elevated pCO2

While solar ultraviolet radiation (UVR) is known to impact zooplankton, little has been documented on its impacts under elevated pCO2. Here, we show that exposure to UVR decreased the feeding and survival rates of the copepod Acartia spinicauda, that artificial UV-B of 2.25 W·m−2 for 4 h resulted in a 52 % inhibition of its grazing rates and a 45 % reduction in survival rates compared to visible light alone. On the other hand, an increase in pCO2 to 1000 μatm (pH drop of 0.4) immediately and significantly increased the UVR-induced inhibition of feeding. Subsequently, the combination of the high pCO2 (1000 μatm) and UVR resulted in about 65 % lethal impact, with UV-A contributing 21 % and UV-B 44 % compared to the visible light alone and ambient pCO2 conditions. While the copepod was shown to be able to sense and escape from UV-exposed areas, these findings suggest that UVR impacts on the copepod can be exacerbated with progressive ocean acidification or in high CO2 waters, including upwelled regions.

One-class modelling applied to ATR-FTIR spectroscopy for determining document forgeries related to paper aging

One of the great challenges of document analysis is determining document forgeries. The present work proposes a non-destructive approach to discriminate natural and artificially aged papers using infrared spectroscopy and soft independent modeling by class analogy (SIMCA) algorithms. This is of particular interest in cases of document falsifications made by artificial aging, for this study, SIMCA, and Data-Driven SIMCA (DD-SIMCA) classification models were built using naturally aged paper samples, taken from three time periods: 1st period from 1998 to 2003; 2nd period from 2004 to 2009; and 3rd period from 2010 to 2015. Artificially aged samples (exposed to high temperature or UV radiation) were used as test sets. Promising results in detecting document falsifications related to aging were obtained. Samples artificially aged at high temperature were correctly discriminated from the authentic samples (naturally aged) with 100% accuracy. In contrast, the samples under the photodegradation process showed a lower classification performance, with results above 90%.

Extraction of phenolic compounds from Moringa oleifera Lam. leaves with ultrasonic-assisted deep eutectic solvents.

In this study, deep eutectic solvents (DESs) combined with ultrasound-assisted extraction (UAE) were used to extract bioactive compounds from the leaves of Moringa oleifera Lam. The FT-IR method was used to analyze the structural characteristics of the DESs, and the extraction efficiencies of the DESs for total phenolic content (TPC) and total flavonoid content (TFC) were evaluated. The stability of the extracts under high temperature and UV radiation was assessed, and their antioxidant activity was investigated after undergoing in vitro simulated digestion. The results show that the seven DESs extracted more TPC and TFC than did the 70% ethanol (36.27 ± 1.58 mg GAE/g, 23.09 ± 1.47 mg RT/g), and the extraction process of UAE-DES was optimized by selecting choline chloride: citric acid as the DES solvent, which has the highest extraction of TPC (86.92 ± 1.34 mg GAE/g) and TFC (49.73 ± 0.85 mg RT/g). The stability results indicated that the DES phenolic extracts were less stable when exposed to high temperature and UV radiation, indicating that DES extracts have better bioactivity. Moreover, after in vitro simulated digestion, the DES extract shows a higher DPPH free radical scavenging capacity (12.79 ± 3.88 mmol Trolox/g of DES extracts, 6.99 ± 4.02 mmol Trolox/g of ethanol extracts) and ferric ion reducing antioxidant power (62.61 ± 1.71 mmol Trolox/g of DES extracts, 55.07 ± 1.66 mmol Trolox/g of ethanol extracts) than ethanol extracts. This study confirmed that DESs are a new and environmentally friendly solvent that can be used for the extraction of phenolic compounds.

The photoreactivation of 6 − 4 photoproducts in chloroplast and nuclear DNA depends on the amount of the Arabidopsis UV repair defective 3 protein

Background6 − 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.ResultsUsing 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.ConclusionsPhotolyases 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.

The astrobiological potential of the Makgadikgadi Basin, Botswana: Field analogue for planetary exploration

Terrestrial analogue sites have been crucial for studying Martian geology and mineralogy, integrating the direct evidence available from Mars through remote sensing and in situ measurements carried out by the instruments on board robotic missions. Studying readily available and accessible terrestrial analogues of Martian fossil or extant environments is considered the most efficient way to answer crucial scientific questions. These analogues offer opportunities to collect a range of geological and microbiological data. The Makgadikgadi Basin (MKB) in Botswana is one of such environments hosting a system of salt pans presenting striking similarities with Mars playa deposits. The MKB presents layered mounds, relict fan deltas with inverted channels, polygonal structures and evaporitic crusts harboring communities of extremophiles. The present-day MKB is predominantly fed by groundwater and local precipitations in an overall arid to semi-arid climate, characterized by high UV radiation and salinity, deposition of evaporitic minerals and authigenic clays. The shallow subsurface of the MKB pans is covered by diagenetic features (duricrusts) including silcretes and calcretes. These pans can serve as test beds for the physical and chemical characteristics of playa deposits on Mars and help improve our understanding of the conditions that might support life outside our planet.

Iris melanoma in an Australian cohort.

To report the clinicopathological features and epidemiology of iris melanoma in Queensland, Australia. This was a retrospective study of 86 patients with iris melanoma treated between 2001 and 2022 at the Queensland Ocular Oncology Service, Brisbane, Australia. Main outcome measures included demographics, clinical and phenotypic features, age-adjusted incidence and relative survival. Eighty-six patients (63% female) were included. Mean age was 54 years (range 17-82 years). The majority of patients (97%) were Caucasian, with blue eyes, fair skin and Fitzpatrick Skin Type I or II. Demographic features and clinical history showed a tendency for high ultraviolet radiation (UVR) exposure in the cohort. Histopathology was available in 69 cases (82%), and of these, 77% tumours were of spindle cell origin, with low-risk genetic profiles. Patients were followed for a mean of 8 years (median 7, range 1-21 years) after diagnosis, and only one case of metastasis was documented. The association of iris freckles, history of UVR exposure and dermatologic findings supports the role of UVR in iris melanoma. Occupation and avocation history, as well as evaluation of iris freckles may offer an easily accessible way of stratifying the risk of an individual for development of UVR-related uveal melanoma.