Solar UV-B Research Articles

Cell damage repair mechanism in a desert green algae Chlorella sp. against UV-B radiation

The protective ozone layer is continually depleting owing to an increase in the levels of solar UV-B radiation, which has harmful effects on organisms. Algae in desert soil can resist UV-B radiation, but most research on the radiation resistance of desert algae has focused on cyanobacteria. In this study, we found that desert green algae, Chlorella sp., could maintain high photosynthetic activity under UV-B stress. To examine the tolerance mechanism of the desert green algae photosystem, we observed the physiological and transcriptome-level responses of Chlorella sp. to high doses of UV-B radiation. The results showed that the reactive oxygen species (ROS) content first increased and then decreased, while the malondialdehyde (MDA) content revealed no notable lipid peroxidation during the UV-B exposure period. These results suggested that Chlorella sp. may have strong system characteristics for scavenging ROS. The antioxidant enzyme system showed efficient alternate coordination, which exhibited a protective effect against enhanced UV-B radiation. DNA damage and the chlorophyll and soluble protein contents had no significant changes in the early irradiation stage; UV-B radiation did not induce extracellular polysaccharides (EPS) synthesis. Transcriptomic data revealed that a strong photosynthetic system, efficient DNA repair, and changes in the expression of genes encoding ribosomal protein (which aid in protein synthesis and improve resistance) are responsible for the high UV-B tolerance characteristics of Chlorella sp. In contrast, EPS synthesis was not the main pathway for UV-B resistance. Our results revealed the potential cell damage repair mechanisms within Chlorella sp. that were associated with high intensity UV-B stress, thereby providing insights into the underlying regulatory adaptations of desert green algae.

Growth of Sphagnum Riparium Contains the Signature of Short Wavelength UV-B Passing Through the Ozone Layer

It follows from the negative reaction of plant growth to UV-B that the wavelengths penetrating through the ozone layer, in contrast to the absorbed ones, should leave a specific signature in the form of growth inhibition. This signature is expected, for example, for peat mosses of the Sphagnum genus. To test this hypothesis, we studied the growth response of Sphagnum riparium Ångstr. to solar UV in the 200-310 nmrange, recorded outside the Earth’s atmosphere. It was found that wavelengths starting from 286 nm significantly inhibited the growth of Sphagnum, while shorter wavelengths hadno significant effect. It follows that wavelengths starting from 286 nm reach the Earth’s surface, while shorter ones are absorbed by the ozone layer. These data correspond to the physical concepts of the 286 nm limit for solar radiation penetration through the ozone layer. Based on the universal UVR8-dependent mechanism of UV-B reception in plants, we conclude that plants have potential as indicators for assessing the penetration of the shortest solar UV-B wavelengths through the ozone layer.
 Keywords: UV-B, 286 nm, Sphagnum, growing season, growth inhibition

Exposure to Low UV-B Dose Induces DNA Double-Strand Breaks Mediated Onset of Endoreduplication in Vigna radiata (L.) R. Wilczek Seedlings.

Multiple lines of evidence indicate that solar UV-B light acts as an important environmental signal in plants, regulating various cellular and metabolic activities, gene expression, growth and development. Here, we show that low levels of UV-B (4.0 kJ m-2) significantly influence plant response during early seedling development in the tropical legume crop Vigna radiata (L.) R. Wilczek. Exposure to low doses of UV-B showed relatively less growth inhibition yet remarkably enhanced lateral root formation in seedlings. Both low and high (8.0 kJ m-2) doses of UV-B treatment induced DNA double-strand breaks and activated the SOG1-related ATM-ATR-mediated DNA damage response pathway. These effects led to G2-M-phase arrest with a compromised expression of the key cell cycle regulators, including CDKB1;1, CDKB2;1 and CYCB1;1, respectively. However, along with these effects, imbibitional exposure of seeds to a low UV-B dose resulted in enhanced accumulation of FZR1/CCS52A, E2Fa and WEE1 kinase and prominent induction of endoreduplication in 7-day-old seedlings. Low dose of UV-B mediated phenotypical responses, while the onset of endoreduplication appeared to be regulated at least in part via UV-B induced reactive oxygen species accumulation. Transcriptome analyses further revealed a network of co-regulated genes associated with DNA repair, cell cycle regulation and oxidative stress response pathways that are activated upon exposure to low doses of UV-B.

Estimation of the Vitamin D (VD) Status of Pregnant Japanese Women Based on Food Intake and VD Synthesis by Solar UV-B Radiation Using a Questionnaire and UV-B Observations

Estimation of the Vitamin D (VD) Status of Pregnant Japanese Women Based on Food Intake and VD Synthesis by Solar UV-B Radiation Using a Questionnaire and UV-B Observations

Relationship Between Vitamin D Supplementation and Improvement in Body for Carcinogenesis: A Literature Review

Vitamins are probably the best-selling dietary supplements in the United States, in which an estimated 35% of the population take multivitamin and mineral supplements. Data relating microconstituents to carcinogenesis are extremely limited, as explained in the first report. A striking feature of many of the compounds in the three groups mentioned above is their capacity to prevent or retard the occurrence of neoplasia. However, there is a paucity of data concerning the conditions under which inhibition occurs, the mechanisms of inhibition, and the precise impact of these microconstituents on humans. A literature review was conducted in the electronic databases PubMed and Google Scholar using the index terms "carcinogenesis" and "cancer" and "vitamin D" All types of studies were included for this study, such as randomized controlled trials, systematic reviews, literature reviews, and pilot studies published between 2010 and 2021. Articles which not written in English were excluded from the study. This search resulted in 10 papers. Many of the mechanisms proposed for vitamin D and cancer prevention have been studied only in the context of one tissue or one type of cancer and so further studies must be conducted to determine if these mechanisms can be generalized. For example, while higher serum (25(OH)D3) is associated with reduced cancer risk, and CYP27B1 is expressed in non-renal cells, there is no evidence that the low-level expression of CYP27B1 in tissues leads to meaningful local production of 1a,25(OH)2D3 or calcitriol, and that this mediates the protection from cancer provided by high vitamin D status. In conclusion, we suggest that vitamin D compounds to be employed in the treatment of, alone or in combination with other anticancer agents. solar UV-B radiation, acting through the production of vitamin D, is a risk reduction factor for over a dozen forms of cancer.

Spectral Blocking of Solar Radiation in High Tunnels by Poly Covers: Its Impact on Nutritional Quality Regarding Essential Nutrients and Health-Promoting Phytochemicals in Lettuce and Tomato

Spectral characteristics of solar radiation have a major role in plant growth and development and the overall metabolism, including secondary metabolism, which is important for the accumulation of health-promoting phytochemicals in plants. The primary focus of this study was to determine the effect of spectral characteristics of solar radiation on the nutritional quality of lettuce (Lactuca sativa L., cv. red leaf ‘New Red Fire’ and green leaf ‘Two Star’ and tomato (Solanum lycopersicum L., cv. BHN-589) grown in high tunnels in relation to the accumulation of essential nutrients and phytochemicals. Solar spectrum received by crops was modified using photo-selective poly covers. Treatments included commonly used standard poly, luminescence poly (diffuse poly), clear poly, UV blocking poly, exposure of crops grown under the standard poly to full sun 2 weeks prior to harvest (akin to movable tunnel), and 55% shade cloth on the standard poly. All the poly covers and shade cloth reduced the PAR levels in the high tunnels, and the largest reduction was by the shade cloth, which reduced the solar PAR by approximately 48%. Clear poly allowed the maximum UV-A and UV-B radiation, while standard poly allowed only a small fraction of the solar UV-A and UV-B (between 15.8% and 16.2%). Clear poly, which allowed a higher percentage of solar UV-A (60.5%) and UV-B (65%) than other poly covers, increased the total phenolic concentration and the antioxidant capacity in red leaf lettuce. It also increased the accumulation of flavonoids, including quercetin-3-glucoside, luteolin-7-glucoside, and apigenin-3-glucoside in red leaf lettuce, compared to the standard poly. Brief exposure of crops grown in high tunnels to full sun prior to harvest produced the largest increase in the accumulation of quercetin-3-glucoside, and it also resulted in an increase in luteolin-7-glucoside and apigenin-3-glucoside in red leaf lettuce. Thus, clear poly and brief exposure of red leaf lettuce to the full sun, which can increase UV exposure to the plants, produced a positive impact on its nutritional quality. In contrast, shade cloth which allowed the lowest levels of solar PAR, UV-A and UV-B relative to the other poly covers had a negative impact on the accumulation of the phenolic compounds in red leaf lettuce. However, in green leaf lettuce, luminesce poly, clear poly, UV-block poly, and shade treatments increased the accumulation of many essential nutrients, including protein, magnesium, and sulfur in green leaf lettuce compared to the standard poly. Poly cover treatments including shade treatment did not affect the accumulation of either carotenoids (lutein, β-carotene, and lycopene) or essential nutrients in mature tomato fruits. The results show that clear poly cover can enhance the accumulation of many phenolic compounds in red leaf lettuce, as does the brief exposure of the crop to the full sun prior to harvest. Thus, UV radiation plays an important role in the accumulation of phenolic compounds in red leaf lettuce while the overall spectral quality of solar radiation has a significant influence on the accumulation of essential nutrients in green leaf lettuce.

Spectra of Photobiological Inactivation of SARS-CoV-2 by Solar UVB Radiation (280–320 nm)

Primary photoacceptors and spectra of photobiological inactivation of the SARS-CoV-2 molecular structures (genome and S-spike protein) by UVB radiation were determined for the first time based on experimental ground-based observations of the intensity and spectrum of solar UVB radiation in Tomsk (56°29′ N, 84°56.89′ E) from March 26, 2020, to March 26, 2021, and the analysis of works on the structure and chemical molecular composition of SARS-CoV-2.

A revised action spectrum for vitamin D synthesis by suberythemal UV radiation exposure in humans in vivo

Action spectra are important biological weighting functions for risk/benefit analyses of ultraviolet (UV) radiation (UVR) exposure. One important human benefit of exposure to terrestrial solar UVB radiation (∼295 to 315 nm) is the cutaneous synthesis of vitamin D3 that is initiated by the photoconversion of 7-dehydrocholesterol to previtamin D3 An action spectrum for this process that is followed by other nonphotochemical steps to achieve biologically active vitamin D3 has been established from ex vivo data and is widely used, although its validity has been questioned. We tested this action spectrum in vivo by full- or partial-body suberythemal irradiation of 75 healthy young volunteers with five different polychromatic UVR spectra on five serial occasions. Serum 25-hydroxyvitamin D3 [25(OH)D3] levels, as the most accurate measure of vitamin D3 status, were assessed before, during, and after the exposures. These were then used to generate linear dose-response curves that were different for each UVR spectrum. It was established that the previtamin D3 action spectrum was not valid when related to the serum 25(OH)D3 levels, as weighting the UVR doses with this action spectrum did not result in a common regression line unless it was adjusted by a blue shift, with 5 nm giving the best fit. Such a blue shift is in accord with the published in vitro action spectra for vitamin D3 synthesis. Thus, calculations regarding the risk (typically erythema) versus the benefit of exposure to solar UVR based on the ex vivo previtamin D3 action spectrum require revision.

Solar UV-B effects on composition and UV screening efficiency of foliar phenolics in Arabidopsis thaliana are augmented by temperature.

The accumulation of foliar phenolics constitutes one strategy of plants against the potentially harmful effects of ultraviolet-B and A (UV-B, UV-A) radiation. These compounds protect photosensitive tissues by shielding and antioxidative function. It is unknown, however, whether seasonal acclimation to natural conditions may modify the UV-B effect on phenylpropanoid composition and localisation, and thus their screening efficiency. To address this debate, a field experiment with the wildtype of Arabidopsis thaliana accession Landsberg erecta (Ler) was implemented over a whole year with plants exposed to different UV-filter treatments. While seasonal increases of UV-B radiation had a slight negative effect on the amount of hydroxycinnamic acids (HCAs), low temperatures increased foliar HCAs. HCAs, however, did not contribute substantially to seasonal changes of in vivo UV absorbance. Kaempferol and quercetin derivatives increased significantly under ambient UV-B radiation, and low temperature interacted with this effect. A shift of epidermal UV-A shielding from kaempferol to quercetin derivatives was elucidated in UV-B presence. Despite this, a substantial 20-fold increase of quercetin derivatives, during periods with high irradiance and low temperature, did not affect UV absorbance leading to the conclusion that quercetin accumulation was not exclusively in epidermal vacuoles. Using confocal microscopy, the potential occurrence of quercetin in mesophyll cells was demonstrated in plants grown with experimental UV-B radiation at low temperature for the first time in A. thaliana. The presented study discusses the idea that cross-talk of UV-B radiation and temperature might adjust the physiological function of quercetin from an (epidermal) screening to an antioxidant substance.

Generation of nanoplastics during the photoageing of low-density polyethylene

In this work, we studied the hydrolytic and photochemical degradation of three low-density polyethylene (LDPE) materials, within the size range of microplastics (MP). The MPs were exposed to mechanical agitation and UV irradiation equivalent to one year of solar UVB + UVA in a stirred photoreactor. Flow cytometry was used to track the formation of small (1–25 μm) MPs by applying Mie's theory to derive the size of MP particles from scattering intensity readings. The calculation was based on a calibration with polystyrene (PS) beads. The results showed that the generation of 1–5 μm MP reached 104-105 MPs in the 1–25 μm range per gram of LDPE. ATR-FTIR and micro-FTIR measurements evidenced the formation of oxygenated moieties, namely hydroxyl, carbonyl, and carbon-oxygen bonds, which increased with irradiation time. We also found evidence of the production of a high number of nanoplastics (<1 μm, NPs). The Dynamic Light Scattering size of secondary NPs was in the hundreds of nm range and might represent up to 1010 NPs per gram of LDPE. Our results allowed the unambiguous spectroscopic assessment of the generation of NPs from LDPE under conditions simulating environmental exposure to UV irradiation and used flow cytometry for the first-time to track the formation of secondary MPs.

The effects of increased exposure time to UV-B radiation on germination and seedling development of Anatolian black pine seeds.

Exhaustion of stratospheric ozone found at a height of 10-30 km around the world causes the solar UV-B (280-320 nm) radiation to penetrate through the atmosphere more, and thus to reach the Earth's surface quicker. The protective ozone layer gets damaged by human activities constantly, and the increasing levels of UV radiation present threats to all life forms, plants, animals, and even microorganisms. However, the studies conducted on the effects of UV radiation on plants, and especially forest trees, are rather limited. In this study, it was aimed to identify the effects of UV-B radiation on some germination and seedling characteristics of Anatolian black pine seeds. Within the scope of the study, seeds were exposed to UV-B radiation for 5, 10, 20, 30, 40, 50, and 60 min for germination experiments; and the germination speed (GS) was calculated as the ratio of the germinated seeds to the solid seeds at the end of the 7th day, whereas the germination percentage (GP) was calculated as the ratio of the germinated seeds to the solid seeds at the end of the 35th day. The seeds reserved for the seedling experiment were exposed to UV-B radiation for 1, 3, 5, and 7 h. With the measurements made at the end of the day, the seedling length (SL), the terminal bud length (TBL), the branch number (BN), the root collar diameter (RCD), the stem fresh weight (SFW), the root fresh weight (RFW), the stem dry weight (SDW) and the root dry weight (RDW), and the rooting percentage (RP) were determined. Variance analysis and Duncan test were applied to the obtained data with the help of SPSS package program. The study results revealed that the exposure time to increased UV-B radiation significantly affected all characters; the least affected character was RP, and that the most affected characters were RDW, SDW, and RCD. As a result of the study, it was found that even the applications with the lowest intensity took effect in most of the characters, that the seedling development decreased by more than 80% in terms of some characters at the end of 7-h application, and that even the decrease in the RP character, which was the least affected by the 7-h UV-B application, was above 50%.

Endocrinology, Vitamin D and the UK’s Covid-19 Disaster

The formation of cholecalciferol (Vitamin D3) in skin depends on solar UVB to break the B ring of 7-dehydrocholesterol. Its discovery more than a century ago resulted from the identification of rickets as due to deficient sunshine in latitudes far from the equator, exacerbated by the air pollution, factory work and indoor living. Rickets resulted from defective endocrine control of blood calcium, and was accompanied by epidemic tuberculosis from failure of the D3-dependent first-line immune system. The influenza pandemic of 2018 revealed the need for D3 to fight viruses. Half a century later the systemic hormone role of 1,25(OH)D3 of renal origin, under control of PTH, was a major stimulus to understanding the mechanism of action via the VDR-RXR heterodimer. It was soon realised that 1,25(OH)D3 is also produced and acts locally in many organs and tissues provided that there are adequate reserves of the (protein-bound) blood storage form, 25(OH)D. This is the common pool for 1-hydroxylation by any cells that need local activation of VDR for induction of specific genes. In the case of the immune system, the trigger is foreign proteins recognised as ‘non-self’. Local production and action of 1,25(OH)D, and then its local destruction by 24-hydroxylation must all occur below the ‘endocrine radar’, so as not to interfere with systemic calcium control. Coronaviruses through their ‘spike’ protein are internalised by interacting with the ACE-2 receptor, which in turn is down-regulated by Vitamin D. In the process, 25(OH)D is hydroxylated to the active 1,25(OH)D, which must later be degraded to 1,24,25(OH)D. So it is to be expected that when 25(OH)D reserves are low at the onset of infection, they will fall further, allowing virus to enter the cells and trigger a cytokine storm and other damage. Blood PTH will rise to claim any residual 25(OH)D for the dominating systemic role in calcium homeostasis. It follows that intake of vitamin D3 should always be much more than the minimum claimed by the globally-active endocrine system. Unfortunately, the UK’s Specialised Advisory Committee on Nutrition (SACN), does not recognise this. It is dominated by nutritionists, even though food sources of D3 are for most non-existent, and of D2, the vegetable substitute, highly variable. The 400IU of D3 reluctantly recommended for those ‘at risk’, based on endocrinology alone, is grossly inadequate; 4,000IU daily is needed to maintain a blood 25(OH)D at more than 30 ng/ml (75 nmol/l), and provide sufficient reserve for its many autocrine and paracrine functions. The dangers of letting the dominant endocrine function of 1,25(OH)D in ionic calcium control dictate the level of D3 supplements, have once again been underlined by the Covid-19 disaster.

Assessment of solar ultraviolet radiation in Tabriz city, Iran

Background: The solar radiation consists of a vast spectrum of wavelengths such as visible light and ultraviolet radiation (UVR). The amount of UVR that reaches the Earth's surface is very important due to its role in vitamin D synthesis and causing skin cancers. The hourly and daily mean values of solar UV type A, B, and visible light radiation were measured for the first time during the year. Materials and Methods: The hourly and daily mean values of UVR and visible light intensity of solar radiation at Tabriz were measured and analyzed between the 2017 and 2018 years. The intensity of solar UVA and UVB radiation was measured by Hand-held Lux-UV meter device from sunrise to sunset for one hour. Results: The results showed that the highest values of UVA and UVB radiation, reaching the Earth were between 12 and 13 o’clock. The maximum and minimum values of UVR were recorded during the months of May and January, respectively. The maximum amounts of UVA and UVB during the whole year were 52.48 and 2.82 W/m2, respectively. Also, the lowest intensity of UVA and UVB radiation during the whole year was 22.19 and 0.79 W/m2, respectively. Conclusion: Comparison of maximum and minimum UV amounts of type A and B in May was about 2.36 and 3.56 times more than in January. The measurements showed that the intensity of UVA was significantly higher than UVB amounts.

The effects of the printing direction and UV artificial degradation on the mechanical properties using AM PolyJet technology

This study addresses differences in the material properties due to the influence of the printing direction, UV degradation and the use of differently coloured materials. The specimens were manufactured employing PolyJet technology from the Vero material (VeroBlue, VeroYellow, VeroMagenta). Subsequently, the specimens were subjected to tension and compression testing. Ageing is simulated via the exposure of the specimens to solar UVA and UVB for 15 and 30 days (the calculated daylight UV exposure for half a year and a whole year, respectively). The differences in the material properties were also determined according to the types of material. The results were then subjected to a statistical analysis.

Sun Exposure and Vitamin D.

Vitamin D is generally accepted in its importance on the regulation of calcium homeostasis and bone metabolism. Moreover, further health effects due to vitamin D are under discussion. In its effect, vitamin D is more like a hormone. In the classic view, a vitamin is an essential nutrient, which cannot be synthesized independently in the body. Besides nutrition, vitamin D will be produced in the body itself. The skin contains the provitamin D3 7-dehydrocholesterol, a precursor of vitamin D. Provitamin D3 will be photoconverted to previtamin D3 by UVB radiation that penetrates the skin superficially. In this way, the vitamin D metabolism will be started independent of the nutrition. In everyday life, this photosynthesis will be carried out due to the solar UVB radiation penetrating the uncovered skin. In the same spectral waveband range of UVB radiation, which causes the beneficial health effect of starting the vitamin D metabolism, the UVB radiation causes simultaneously acute and chronic harmful health effects as UV erythema (sunburn), skin aging and skin cancer. There is no vitamin D production in the skin without simultaneous DNA damage in the skin. Against this background, risks and benefits have to be balanced carefully.

Spectra of photobiological inactivation of SARS-CoV-2 by solar UVB radiation (280-320 nm)

Spectra of photobiological inactivation of SARS-CoV-2 by solar UVB radiation (280-320 nm)

İZMİR İLİNDE AL2O3: C DOZİMETRELER KULLANILARAK SOLAR UVB RADYASYONUNUN ÖLÇÜLMESİ

It is well known that UV radiation has a significant effect on our ecologic system. The risks that may be caused by the increases in ultraviolet (UV) radiation reaching the earth’s surface due to the depletion of stratospheric ozone have been studied by many researchers. Although UVB radiation consists only a small fraction of the global solar UV radiation, it causes harmful effects on human, animal and plant. Furthermore, UVB may have several adverse effects on living organism in terrestrial and sea ecosystem. The aim of this work is to investigate the usability of thermoluminescence dosimeters (TLDs) in measuring the solar UVB radiation. TLDs have some superior characteristics such as their availability, being cheap and easy to use. In this study, we used Al2O3:C thermoluminescence dosimeters for measuring the UVB radiation, They are very sensitive to low ionizing radiation doses and UVB radiation. The daily exposures of the ground surface UVB radiation were periodically measured using aluminium oxide dosimeters. The measurements were taken from 09:00 to 16:00 in each study day. Obtained results were observed to be consistent with the UV data received from Ege University, Solar Energy Institute.

DESENVOLVIMENTO DE UM FOTOPROTETOR COM ÓLEO ESSENCIAL DE CANELA

Ativos naturais ao serem adicionados às formulações de fotoprotetores aumentam sua eficácia. Dessa forma, o objetivo desse trabalho foi avaliar a proteção frente à radiação UV do óleo essencial de canela (Cinnamomum cassia) e desenvolver um fotoprotetor. O óleo essencial de canela obtido de uma farmácia de manipulação foi analisado espectrofotométricamente nos comprimentos de onda de 210 a 400 nm (UVC-UVA). A concentração com a maior capacidade de proteção foi incorporada à base creme para o desenvolvimento de um fotoprotetor. Para a avaliação da proteção frente à radiação solar o fotoprotetor desenvolvido foi diluído a 10%(m/v) em álcool etílico absoluto e foi analisado espectrofotometricamente nos mesmos comprimentos de onda (UVC-UVA). O fotoprotetor com óleo essencial de canela na concentração de 1,5%(v/v) apresentou proteção frente à radiação solar UVB e UVA (280-400nm). A fórmula desenvolvida apresentou FPS 6,3, dentro do preconizado pela legislação brasileira que exige um FPS de no mínimo 6. O óleo essencial de canela apresentou potencial para ser utilizado como fotoprotetor em associação com outros produtos visto que não absorveu em toda faixa da radiação UVA. A atividade fotoprotetora pode estar relacionada ao seu potencial antioxidante. Novos estudos devem ser realizados para verificar a associação do óleo essencial de canela com outras substâncias fotoprotetoras e comprovar o aumento do potencial protetor relacionado à atividade antioxidante.

Preserved riparian forest protects endangered forest-specialists amphibian species against the genotoxic impact of sunlight and agrochemicals

Although agrochemicals and solar ultraviolet (UV) radiation are both environmental stressors currently associated with amphibian decline, little is known about their interactive effects on amphibian larvae. One potential hazardous consequence of this interaction could be the increase of chromosomal damage and induction of cell death, which culminate in tadpole mortality. In this study, the preservation level of the riparian forest of four different streams located at the Atlantic Forest in southern Brazil was evaluated through satellite imagery analysis. The incidence of solar UVB and UVA radiation were measured with a radiometer in the amphibian breeding sites, and the presence of agrochemicals in the water was quantified through liquid chromatography coupled in tandem to mass spectrometry. Tadpole population density of two endangered forest-specialist amphibian species (Boana curupi and Crossodactylus schmidti) was evaluated in each stream, and the chromosomal damage of the collected larvae was determined through cytogenetic analysis of blood samples. The results clearly indicate that the preservation of riparian forest efficiently blocks the incidence of UV radiation upon the water surface and reduce by 2.7-fold the entry of agrochemicals from adjacent agricultural crops. Tadpoles collected in streams with preserved and continuous riparian forest presented a significantly lower amount of micronuclei, as well as higher population density in comparison to tadpoles collected in streams located in converted agricultural landscape. Therefore, this study demonstrates that the preservation of the riparian forest has paramount importance in reducing the impact of environmental genotoxic agents into lotic breeding sites used by forest-specialist amphibian species.

Environmental and ecological factors of stomach cancer incidence and mortality: a systematic review study on ecological studies.

Stomach cancer (SC) is one of the most common and deadly types of cancer. It is the third leading cause of cancer deaths worldwide. The effect of environmental and ecological factors in SC have been assessed in some studies. Thus, we aimed to synthesize the environmental and ecological factors of SC incidence and mortality. In this systematic review study, the scientific databases, including Web of Science, Scopus and PubMed, were searched from inception to November 2019 for all primary articles written in English by using relevant Medical Subject Heading (Mesh) terms. Two independent authors conducted the screening process to decide on the eligibility and inclusion of the articles in the study. Thethird author acted as an arbiter to resolve any disagreements. A total of 157 potentially relevant articles were identified from the initial search 38 of which met the eligibility criteria; finally, 34 articles were included in the systematic review. The results revealed that soil arsenic exposure, coal and other opencast mining installations, living near incinerators and installations for the recovery or disposal of hazardous waste, installations for the production of cement, lime, plaster, and magnesium oxide, proximity to a metal industry sources, dietary iron, ingested asbestos, farming, arsenic in soil, altitude, organochlorines and environmental exposure to cadmium and lead have positive associations with SC incidence or death. Most of the ecological and environmental factors such as living near the mineral industries, the disposal of hazardous waste, metal industry sources and environmental exposure to cadmium and lead are positively related to SC mortality and incidence. However, solar UV-B, heat index and dietary zinc can be taken into account as protective factors against SC mortality and incidence.