DNA damage after acute exposure of mice skin to physiological doses of UVB and UVA light

UV index-based model for predicting synthesis of (pre-)vitamin D3 in the mediterranean basin

The importance of solar radiation for the body's ability to synthesize Vitamin D3 is well documented, yet the precise amount of sun exposure required to avoid Vitamin D insufficiency is less clear. To address this knowledge gap, this study sought to utilize the sun in a suitable period at the optimum dose by utilizing numerical simulations to determine the amount of Vitamin D3 synthesis in the skin according to season, time of day, and geographical location in Turkey. The study was carried out in three stages; in the first stage, daily, monthly, and annual values were determined in cases where the solar zenith angle has the active UV-B wavelength. The second stage determined the level of Vitamin D that can be synthesized in all skin types at 25% solar radiation exposure. In the third stage, the sun exposure time required for 1000 International Units (IU) for all skin types was calculated. According to the analysis, the yearly period of active synthesis of D3 on Earth lasts from the beginning of March to the third week of October. During the day, it is between 10:00 and 16:00. For 1000 IU/day, the average annual estimated times (minutes) are 5.05 for Type I, 6.3 for Type II, 7.6 for Type III, 11.35 for Type IV, 15.15 for Type V, and 25.25 for Type VI. The results of this paper will impact awareness for academic-medical users.

Antioxidant peptides, the guardian of life from oxidative stress

Reactive oxygen species (ROS) are produced during oxidative metabolism in aerobic organisms. Under normal conditions, ROS production and elimination are in a relatively balanced state. However, under internal or external environmental stress, such as high glucose levels or UV radiation, ROS production can increase significantly, leading to oxidative stress. Excess ROS production not only damages biomolecules but is also closely associated with the pathogenesis of many diseases, such as skin photoaging, diabetes, and cancer. Antioxidant peptides (AOPs) are naturally occurring or artificially designed peptides that can reduce the levels of ROS and other pro-oxidants, thus showing great potential in the treatment of oxidative stress-related diseases. In this review, we discussed ROS production and its role in inducing oxidative stress-related diseases in humans. Additionally, we discussed the sources, mechanism of action, and evaluation methods of AOPs and provided directions for future studies on AOPs.

Long Non-coding RNA H19-Overexpressing Exosomes Ameliorate UVB-Induced Photoaging by Upregulating SIRT1 Via Sponging miR-138

UVB-induced photoaging is characterized by wrinkle formation, slackness and senile plaques, affecting the health and beauty of human being. Our previous study revealed that exosomes derived from adipose-derived stem cells (ADSCs) could efficiently alleviate UVB-induced photodamage. However, the functional ingredients in exosomes were undefined. LncRNA H19, one of the well-researched lncRNAs in exosomes, exhibits multiple physiological effects. This study aims to demonstrate the photo-protective role of lncRNA H19 on skin photoaging in UVB-irradiated human skin fibroblasts cells (HSFs) and Kunming mice. LncRNA H19-overexpressing exosomes (H19-Exo) were isolated from the supernatant of ADSCs infected with lncRNA H19-loaded lentivirus. The results showed that H19-Exo significantly inhibited MMPs production, DNA damage and ROS generation while enhancing procollagen type I synthesis in UVB-irradiated HSFs. Meanwhile, H19-Exo markedly reversed epidermal thickening and collagen degradation in UVB-irradiated mice. Furthermore, luciferase reporter assays indicated that lncRNA H19 acted as a sponge for miR-138 expression, and SIRT1 was targeted by miR-138. Evidence from both in vitro and in vivo studies also revealed that H19-Exo could enhance SIRT1 expression by knocking down miR-138. In conclusion, lncRNA H19 served as a therapeutic candidate in treating UVB-induced skin photoaging by upregulation of SIRT1 via miR-138.

Advances in Gelatin Bioinks to Optimize Bioprinted Cell Functions

Gelatin is a widely utilized bioprinting biomaterial due to its cell-adhesive and enzymatically cleavable properties, which improve cell adhesion and growth. Gelatin is often covalently cross-linked to stabilize bioprinted structures, yet the covalently cross-linked matrix is unable to recapitulate the dynamic microenvironment of the natural extracellular matrix (ECM), thereby limiting the functions of bioprinted cells. To some extent, a double network bioink can provide a more ECM-mimetic, bioprinted niche for cell growth. More recently, gelatin matrices are being designed using reversible cross-linking methods that can emulate the dynamic mechanical properties of the ECM. This review analyzes the progress in developing gelatin bioink formulations for 3D cell culture, and critically analyzes the bioprinting and cross-linking techniques, with a focus on strategies to optimize the functions of bioprinted cells. This review discusses new cross-linking chemistries that recapitulate the viscoelastic, stress-relaxing microenvironment of the ECM, and enable advanced cell functions, yet are less explored in engineering the gelatin bioink. Finally, this work presents the perspective on the areas of future research and argues that the next generation of gelatin bioinks should be designed by considering cell-matrix interactions, and bioprinted constructs should be validated against currently established 3D cell culture standards to achieve improved therapeutic outcomes.

Transcriptome analysis of pika heart tissue reveals mechanisms underlying the adaptation of a keystone species on the roof of the world

High-altitude environments impose intense stresses on living organisms and drive striking phenotypic and genetic adaptations, such as hypoxia resistance, cold tolerance, and increases in metabolic capacity and body mass. As one of the most successful and dominant mammals on the Qinghai-Tibetan Plateau (QHTP), the plateau pika (Ochotona curzoniae) has adapted to the extreme environments of the highest altitudes of this region and exhibits tolerance to cold and hypoxia, in contrast to closely related species that inhabit the peripheral alpine bush or forests. To explore the potential genetic mechanisms underlying the adaptation of O. curzoniae to a high-altitude environment, we sequenced the heart tissue transcriptomes of adult plateau pikas (comparing specimens from sites at two different altitudes) and Gansu pikas (O. cansus). Differential expression analysis and weighted gene co-expression network analysis (WGCNA) were used to identify differentially expressed genes (DEGs) and their primary functions. Key genes and pathways related to high-altitude adaptation were identified. In addition to the biological processes of signal transduction, energy metabolism and material transport, the identified plateau pika genes were mainly enriched in biological pathways such as the negative regulation of smooth muscle cell proliferation, the apoptosis signalling pathway, the cellular response to DNA damage stimulus, and ossification involved in bone maturation and heart development. Our results showed that the plateau pika has adapted to the extreme environments of the QHTP via protection against cardiomyopathy, tissue structure alterations and improvements in the blood circulation system and energy metabolism. These adaptations shed light on how pikas thrive on the roof of the world.

Activation of the JNKs/ATM-p53 axis is indispensable for the cytoprotection of dermal fibroblasts exposed to UVB radiation

Although UVB radiation is mainly absorbed by the epidermis, ~5-10% of its photons reach and affect the upper part of the dermis. Physiologically relevant UVB doses, able to provoke erythema, induce apoptosis in human dermal fibroblasts in vitro, as well as in the dermis of SKH-1 mice. Given the sparse and even contradictory existing information on the effect of UVB radiation on dermal fibroblasts' viability, aim of this work was to unravel the crucial signaling pathways regulating the survival of UVB-treated human dermal fibroblasts. We found that UVB radiation immediately stimulates the phosphorylation of MAPK family members, as well as Akt, and is genotoxic leading to the delayed ATM-p53 axis activation. Akt phosphorylation after UVB radiation is EGFR-mediated and EGFR inhibition leads to a further decrease of viability, while the Akt activator SC79 rescues fibroblasts to an extent by a mechanism involving Nrf2 activation. The known Nrf2 activator sulforaphane also exerts a partial protective effect, although by acting in a distinct mechanism from SC79. On the other hand, inhibition of JNKs or of the ATM-p53 axis leads to a complete loss of viability after UVB irradiation. Interestingly, JNKs activation is necessary for p53 phosphorylation, while the ATM-p53 pathway is required for the long-term activation of JNKs and Akt, reassuring the protection from UVB. Although UVB radiation results in intense and prolonged increase of intracellular ROS levels, classical anti-oxidants, such as Trolox, are unable to affect Akt, JNKs, or p53 phosphorylation and to reverse the loss of fibroblasts' viability. Collectively, here we provide evidence that the main viability-regulating UVB-triggered biochemical pathways act synergistically towards the protection of human dermal fibroblasts, with EGFR/Akt and Nrf2 serving as auxiliary anti-apoptotic machineries, while JNKs/ATM-p53 activation and interplay being overriding and indispensable for the perpetuation of cellular defense and the maintenance of cell viability.

Spectrally-selective mid-IR laser-induced inactivation of pathogenic bacteria

Micrometer-thick layers of Pseudomonas aeruginosa bacteria were prepared on fluorite substrates and scanned by focused mid-IR femtosecond laser radiation that was spectrally tuned to achieve the selective excitation of either the stretching C-H vibrations (3 μm), or stretching C = O, C-N vibrations (6 μm) of the amide groups in the bacteria. The enhanced biocidal efficiency of the latter selective excitation, compared to the more uniform 3-μm laser excitation, was demonstrated by performing viability assays of laser-treated bacterial layers. The bacterial inactivation by the 6-μm ultrashort laser pulses is attributed to dissociative denaturation of lipids and proteins in the cell membranes and intra-cell nucleic acids.

Skin exposure to UVB light induces a skin-brain-gonad axis and sexual behavior

Ultraviolet (UV) light affects endocrinological and behavioral aspects of sexuality via an unknown mechanism. Here we discover that ultraviolet B (UVB) exposure enhances the levels of sex-steroid hormones and sexual behavior, which are mediated by the skin. In female mice, UVB exposure increases hypothalamus-pituitary-gonadal axis hormone levels, resulting in larger ovaries; extends estrus days; and increases anti-Mullerian hormone (AMH) expression. UVB exposure also enhances the sexual responsiveness and attractiveness of females and male-female interactions. Conditional knockout of p53 specifically in skin keratinocytes abolishes the effects of UVB. Thus, UVB triggers a skin-brain-gonadal axis through skin p53 activation. In humans, solar exposure enhances romantic passion in both genders and aggressiveness in men, as seen in analysis of individual questionaries, and positively correlates with testosterone level. Our findings suggest opportunities for treatment of sex-steroid-related dysfunctions.

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UVB exposure increases circulating sex-steroid levels in mice and humans

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UVB exposure enhances female attractiveness and receptiveness toward males

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UVB exposure increases females’ estrus phase, HPG axis hormones, and follicle growth

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Skin p53 regulates UVB-induced sexual behavior and ovarian physiological changes

Regulation of p53 Activity by (+)-Epiloliolide Isolated from Ulva lactuca

Ulva lactuca (U. lactuca) is a green alga distributed worldwide and used as a food and cosmetic material. In our previous study, we determined the effects of U. lactuca methanol extracts on the UVB-induced DNA repair. In the present study, we fractionated U. lactuca methanol extracts to identify the effective compound for the DNA repair. MTT assay demonstrated that (+)-epiloliolide showed no cytotoxicity up to 100 μM in BJ-5ta human dermal fibroblast. Upon no treatment, exposure to UVB 400 J/m² decreased cell viability by 45%, whereas (+)-epiloliolide treatment for 24 h after UVB exposure significantly increased the cell viability. In GO and GESA analysis, a number of differentially expressed genes were uniquely expressed in (+)-epiloliolide treated cells, which were enriched in the p53 signaling pathway and excision repair. Immunofluorescence demonstrated that (+)-epiloliolide increased the nuclear localization of p53. Comet assay demonstrated that (+)-epiloliolide decreased tail moment increased by UVB. Western blot analysis demonstrated that (+)-epiloliolide decreased the levels of p-p53, p21, Bax, and Bim, but increased that of Bcl-2. Reverse transcription PCR (RT-PCR) demonstrated that (+)-epiloliolide decreased the levels of MMP 1, 9, and 13, but increased that of COL1A1. These results suggest that (+)-epiloliolide regulates p53 activity and has protective effects against UVB.

Gene network analysis to determine the effect of hypoxia-associated genes on brain damages and tumorigenesis using an avian model

BACKGROUND

Hypoxia refers to the condition of low oxygen pressure in the atmosphere and characterization of response to hypoxia as a biological complex puzzle, is challenging. Previously, we carried out a comparative genomic study by whole genome resequencing of highland and lowland Iranian native chickens to identify genomic variants associated with hypoxia conditions. Based on our previous findings, we used chicken as a model and the identified hypoxia-associated genes were converted to human's orthologs genes to construct the informative gene network. The main goal of this study was to visualize the features of diseases due to hypoxia-associated genes by gene network analysis.

RESULTS

It was found that hypoxia-associated genes contained several gene networks of disorders such as Parkinson, Alzheimer, cardiomyopathy, drug toxicity, and cancers. We found that biological pathways are involved in mitochondrion dysfunctions including peroxynitrous acid production denoted in brain injuries. Lewy body and neuromelanin were reported as key symptoms in Parkinson disease. Furthermore, calmodulin, and amyloid precursor protein were detected as leader proteins in Alzheimer's diseases. Dexamethasone was reported as the candidate toxic drug under the hypoxia condition that implicates diabetes, osteoporosis, and neurotoxicity. Our results suggested DNA damages caused by the high doses of UV radiation in high-altitude conditions, were associated with breast cancer, ovarian cancer, and colorectal cancer.

CONCLUSIONS

Our results showed that hypoxia-associated genes were enriched in several gene networks of disorders including Parkinson, Alzheimer, cardiomyopathy, drug toxicity, and different types of cancers. Furthermore, we suggested, UV radiation and low oxygen conditions in high-altitude regions may be responsible for the variety of human diseases.

All You Need Is Light. Photorepair of UV-Induced Pyrimidine Dimers

Although solar light is indispensable for the functioning of plants, this environmental factor may also cause damage to living cells. Apart from the visible range, including wavelengths used in photosynthesis, the ultraviolet (UV) light present in solar irradiation reaches the Earth's surface. The high energy of UV causes damage to many cellular components, with DNA as one of the targets. Putting together the puzzle-like elements responsible for the repair of UV-induced DNA damage is of special importance in understanding how plants ensure the stability of their genomes between generations. In this review, we have presented the information on DNA damage produced under UV with a special focus on the pyrimidine dimers formed between the neighboring pyrimidines in a DNA strand. These dimers are highly mutagenic and cytotoxic, thus their repair is essential for the maintenance of suitable genetic information. In prokaryotic and eukaryotic cells, with the exception of placental mammals, this is achieved by means of highly efficient photorepair, dependent on blue/UVA light, which is performed by specialized enzymes known as photolyases. Photolyase properties, as well as their structure, specificity and action mechanism, have been briefly discussed in this paper. Additionally, the main gaps in our knowledge on the functioning of light repair in plant organelles, its regulation and its interaction between different DNA repair systems in plants have been highlighted.

Genotoxic effect of simultaneous therapeutic exposure to polycyclic aromatic hydrocarbons and UV radiation

Polycyclic aromatic hydrocarbons (PAHs) and ultraviolet radiation (UV) represent genotoxic factors that commonly occur in the living and working environment. The dermal form of exposure represents a significant part of the total load of dangerous chemical and physical environmental factors to which an organism is subjected. However, simultaneous dermal exposures to PAHs (pharmaceutical crude coal tar [CCT]) and UV (UVA and UVB) also have therapeutic uses. A typical example is Goeckerman therapy (GT) for psoriasis. The question of the therapeutic efficacy of GT and the related level of genotoxic danger is still under discussion. The aim of the present study was to compare four GT variants (G1-G4) in terms of efficacy and acceptable genotoxic hazard. Efficacy was expressed by the psoriasis area of severity index (PASI) score, genotoxic hazard by chromosomal aberration in peripheral lymphocytes. The lowest risk of genotoxic hazard and the lowest efficiency was observed in G1 variant (3% of the CCT and UVA + UVB). The efficacy of G2 (4% CCT and UVA + UVB), G3 (4% CCT and UVB), and G4 variants (5% CCT and UVA + UVB) was comparable. The highest risk of genotoxic hazard was found in the G3 variant. In the terms of sufficient efficacy and acceptable genotoxic hazard, a combination of 4% or 5% of CCT and UVA and UVB seems to be acceptable (variants G2 and G4).

Repeat UVA exposure of human skin fibroblasts induces both a transitionary and recovery DNA methylation response

Aim: UVA radiation drives skin photoaging in the dermis, plausibly via persistent changes to DNA methylation in dermal fibroblasts. Methods: Genome-wide DNA methylation changes after five repeated daily UVA doses were determined at 48 h (transitionary) and 1 week (recovery) post final irradiation. Results: Differential methylation was found at the transitionary time point in active chromatin states near genes that are highly expressed in fibroblasts and are involved in cellular defensive mechanisms; the majority of these methylation differences were restored to control levels after 7 day recovery. At the recovery time point, new differential methylation occurred at repressed regions near developmental genes, normally weakly expressed in fibroblasts. Conclusion: UVA irradiation induces transitionary and recovery-associated DNA methylation responses in fibroblasts with contrasting functional characteristics.

Plateau Grass and Greenhouse Flower? Distinct Genetic Basis of Closely Related Toad Tadpoles Respectively Adapted to High Altitude and Karst Caves

Genetic adaptation to extremes is a fascinating topic. Nevertheless, few studies have explored the genetic adaptation of closely related species respectively inhabiting distinct extremes. With deep transcriptome sequencing, we attempt to detect the genetic architectures of tadpoles of five closely related toad species adapted to the Tibetan Plateau, middle-altitude mountains and karst caves. Molecular evolution analyses indicated that not only the number of fast evolving genes (FEGs), but also the functioning coverage of FEGs, increased with elevation. Enrichment analyses correspondingly revealed that the highland species had most of the FEGs involved in high-elevation adaptation, for example, amino acid substitutions of XRCC6 in its binding domains might improve the capacity of DNA repair of the toad. Yet, few FEGs and positively selected genes (PSGs) involved in high-elevation adaptation were identified in the cave species, and none of which potentially contributed to cave adaptation. Accordingly, it is speculated that in the closely related toad tadpoles, genetic selection pressures increased with elevation, and cave adaptation was most likely derived from other factors (e.g., gene loss, pseudogenization or deletion), which could not be detected by our analyses. The findings supply a foundation for understanding the genetic adaptations of amphibians inhabiting extremes.

5-aminolaevulinic acid-based photodynamic therapy inhibits ultraviolet B-induced skin photodamage

To evaluate the photoprotective effect of 5-aminolaevulinic acid-based photodynamic therapy (ALA-PDT) on ultraviolet B (UVB)-induced skin photodamage. In vivo experiments, the dorsal skin of hairless mice were treated with ALA-PDT or saline-PDT, and then exposed to 180 mJ/m2 UVB. Results showed that the number of sunburn cells and apoptotic cells in the epidermis of ALA-PDT-treated groups at 24 h after UVB irradiation were significantly decreased compared with those in the UVB groups. And the removal rate of CPDs was obviously higher in ALA-PDT-treated groups. At 48 h, the number of Ki67 positive nuclei in ALA-PDT-UVB group was significantly fewer than that in UVB group. Further in vitro experiments, human keratinocyte cell line (HaCaT) cells of two groups (one treated with ALA-PDT, the other untreated), were exposed to 60 mJ/m2 UVB irradiation. We found 0.5 mmol/L of ALA and 3 J/cm2 of red light did not affect the vitality of cells, and could reduce UVB induced apoptosis, accelerate the clearance of CPDs, inhibit proliferation and activate p53. Thus, our data demonstrate that ALA-PDT pretreatment can induce a protective DNA damage response that protects skin cells from UVB-induced photodamages.

Genomic analysis reveals variant association with high altitude adaptation in native chickens

Native chickens are endangered genetic resources that are kept by farmers for different purposes. Native chickens distributed in a wide range of altitudes, have developed adaptive mechanisms to deal with hypoxia. For the first time, we report variants associated with high-altitude adaptation in Iranian native chickens by whole genome sequencing of lowland and highland chickens. We found that these adaptive variants are involved in DNA repair, organs development, immune response and histone binding. Amazingly, signature selection analysis demonstrated that differential variants are adaptive in response to hypoxia and are not due to other evolutionary pressures. Cellular component analysis of variants showed that mitochondrion is the most important organelle for hypoxia adaptation. A total of 50 variants was detected in mtDNA for highland and lowland chickens. High-altitude associated with variant discovery highlighted the importance of COX3, a gene involved in cell respiration, in hypoxia adaptation. The results of study suggest that MIR6644-2 is involved in hypoxia and high-altitude adaptations by regulation of embryo development. Finally, 3877 novel SNVs including the mtDNA ones, were submitted to EBI (PRJEB24944). Whole-genome sequencing and variant discovery of native chickens provided novel insights about adaptation mechanisms and highlights the importance of valuable genomic variants in chickens.

The comet assay in animal models: From bugs to whales - (Part 2 Vertebrates)

The comet assay has become one of the methods of choice for the evaluation and measurement of DNA damage. It is sensitive, quick to perform and relatively affordable for the evaluation of DNA damage and repair at the level of individual cells. The comet assay can be applied to virtually any cell type derived from different organs and tissues. Even though the comet assay is predominantly used on human cells, the application of the assay for the evaluation of DNA damage in yeast, plant and animal cells is also quite high, especially in terms of biomonitoring. The present extensive overview on the usage of the comet assay in animal models will cover both terrestrial and water environments. The first part of the review was focused on studies describing the comet assay applied in invertebrates. The second part of the review, (Part 2) will discuss the application of the comet assay in vertebrates covering cyclostomata, fishes, amphibians, reptiles, birds and mammals, in addition to chordates that are regarded as a transitional form towards vertebrates. Besides numerous vertebrate species, the assay is also performed on a range of cells, which includes blood, liver, kidney, brain, gill, bone marrow and sperm cells. These cells are readily used for the evaluation of a wide spectrum of genotoxic agents both in vitro and in vivo. Moreover, the use of vertebrate models and their role in environmental biomonitoring will also be discussed as well as the comparison of the use of the comet assay in vertebrate and human models in line with ethical principles. Although the comet assay in vertebrates is most commonly used in laboratory animals such as mice, rats and lately zebrafish, this paper will only briefly review its use regarding laboratory animal models and rather give special emphasis to the increasing usage of the assay in domestic and wildlife animals as well as in various ecotoxicological studies.

RNA-Seq analysis revealed genes associated with UV-induced cell necrosis through MAPK/TNF-α pathways in human dermal fibroblast cells as an inducer of premature photoaging

Exposing the skin to solar UV radiation induces cascades of signaling pathways and biological alterations such as redox imbalance, suppression of antioxidant genes and programmed cell death. Therefore, the aim of this study was to use RNA-Seq to unravel the effects of UV radiation on Normal Human Adult Fibroblast cells (NHDF). Cells were exposed to UV (20 mJ/cm2 for 3 mins) and incubated for 24 h. Total mRNA from the cells generated libraries of 72,080,648 and 40,750,939 raw reads from UV-treated and control cells respectively. Of the differentially expressed genes (DEGs) produced 2,007 were up-regulated and 2,791 were down-regulated (fold change ≥2, p < 0.05). The expression of 4 genes was validated with RT-qPCR. Chemokine signaling pathways in cancer were significantly activated and antioxidant genes were down-regulated. This study applied Next Generation Sequencing technology to reveal the genes and pathways involved in UV-induced human dermal fibroblast cells necrosis.

Upregulation of autophagy by Ginsenoside Rg2 in MCF-7 cells

Autophagy is a major intracellular degradation process that plays an important role in cell survival, stress responses, nutrient sensing and development. Our previous studies have shown that Rg2, a triterpenoid saponin contained in ginseng, protects cells against UVB-induced genotoxicity by increasing DNA repair, in possible association with modulation of protein levels involved in p53 pathway. In this study, we determined an upregulation of autophagy by Rg2. Rg2 treatment for 24 h in MCF-7, a breast cancer cell, did not show cytotoxicity up to 200 μM. Rg2 also upregulated the level of p-p53, p-AMPK, p-ACC, Atg-7 and LC3-II and decreased the level of p62 in concentration-dependent manners. We also determined the level of p53, AMPK, p62, Atg-7 and LC3 after UVB exposure and subsequent incubation in growth medium for 24 h. UVB increased the level of p-p53, p-AMPK, p-ACC and decreased the levels of p62, Atg-7 and LC3-II. Interestingly, Rg2 treatment for 24 h after UVB exposure increased the levels of p-p53, p-AMPK, p-ACC, Atg-7 and LC3-II and decreased the level of cyclobutane pyrimidine dimer, a UVB-induced DNA damage in concentration-dependent manners. All these results suggest that Rg2 increased autophagy and decreased UVB-induced DNA damage, in possible association with the modulation of protein levels in p53- and autophagic pathways.

Penetrating effect of high-intensity infrared laser pulses through body tissue

Researchers have utilized infrared (IR) lasers as energy sources in laser therapy for curing skin diseases and skin injuries with remarkable effects. Preliminary experiments have also shown that high-intensity IR laser pulses could penetrate thick body tissues, resulting in remarkable effects for recovery from injuries in deep muscles and cartilage tissues. However, for deep-level IR laser therapy, it is unclear how much of the laser power density penetrates the body tissues at certain depths and which of the three major effects of laser irradiation, namely, laser-induced photo-chemical effect, photo-thermal effect and mechanical dragging effect, play a key role in the curing process. Thus, in this study, we developed micro-sized thin-film thermocouple (TFTC) arrays on freestanding Si₃N₄ thin-film windows as sensors for laser power density and local temperature. These devices showed excellent linear responses in output voltage to laser power density with wavelengths in the range of 325-1064 nm, and also indicated the local temperature at the laser spot. We systematically measured the penetrating effect and thermal effect through thick porcine tissues for high-intensity IR pulses with a laser system used in clinical treatment and subtracted the attenuation parameters for the porcine skin, fat and muscle tissue from the experimental data. The results offered reliable quantitative references for safe irradiation doses of high-intensity IR laser pulses in practical laser therapy.

A Wearable Colorimetric Dosimeter to Monitor Sunlight Exposure

The personal ultraviolet (UV) dosimeter is a useful measurement tool to prevent UV induced dermal damages; however, conventional digital dosimeters are either bulky or require external power sources. Here, a wearable, colorimetric UV film dosimeter that provides color transition, from purple to transparent, is reported to indicate the UV dose. The film dosimeter is made of a purple photodegradable dye ((2Z,6Z)-2,6-bis(2-(2,6-diphenyl-4H-thiopyran-4-ylidene)ethylidene)cyclohexanone or DTEC) blended in low density polyethylene film. The DTEC film discolored 3.3 times more under the exposure of UV light (302 nm) than visible light (543 nm), and a UV bandpass filter is developed to increase this selectivity to UV light. The DTEC film completely discolors to transparency in 2 h under an AM 1.5 solar simulator, suggesting the potential as an indicator for individuals with types I-VI skin to predict interventions to avoid sunburn. Finally, the DTEC film is integrated with the UV bandpass filter on a wristband to function as a wearable dosimeter for low cost and convenient monitoring of sunlight exposure.

A mechanism for semaphorin-induced apoptosis: DNA damage of endothelial and myogenic cells in primary cultures from skeletal muscle

One hallmark of cancer is its ability to recruit a vascular supply to support rapid growth. Suppression of angiogenesis holds potential as a second-line or adjuvant therapy to stunt cancer growth, progression, metastasis, and post-resection regeneration. To begin to test the hypothesis that semaphorin 3A and 3F together, will induce endothelial cell apoptosis by inducing DNA damage, mixed primary cultures isolated from normal adult mouse skeletal muscle were treated for 48 hr with Sema3A ± Sema3F (100ng/mL). Changes in surviving-cell density, DNA synthesis, DNA repair (gamma-Histone 2AX, γH2AX, an indirect measure for DNA damage), and apoptotic DNA fragmentation (TUNEL staining) were assayed in cultures of CD31+ endothelial and desmin+ muscle cells. Sema3F increased DNA damage-associated DNA repair in both cell types. Co-treatment with Sema3A+3F increased γH2AX staining ~25-fold over control levels, and further increased apoptosis compared to control and Sema3A alone. Results were negated by treatment with neutralizing anti-semaphorin antibodies and are interpreted as suggesting that Sema3A may sensitize endothelial but not muscle cells to Sema3F-induced DNA damage. These preliminary findings on a complex system of interacting cells may contribute to developing applications that could target angiogenic regulatory mechanisms for their therapeutic potential against cancer progression and metastasis.

MYC gene amplification is a rare event in atypical fibroxanthoma and pleomorphic dermal sarcoma

Atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS) are rare malignancies typically occurring in elderly patients and predominantly located in skin regions exposed to UV-light. Thus, a role of UV-radiation-induced damage for AFX and PDS tumorigenesis has been postulated. MYC gene amplification has been demonstrated as a distinctive feature of radiation-induced angiosarcoma. In order to investigate whether chronic exposure to UV-light might also lead to MYC copy number changes, 51 AFX and 24 PDS samples were retrospectively analyzed for MYC amplification by fluorescence in situ hybridization using a MYC and a CEP8 gene probe. Of the 44 analyzable AFX samples, one case showed MYC amplification (defined as a MYC/CEP8 ratio ≥2.0), whereas 13 cases demonstrated low level copy number gains (defined as MYC/CEP8 ratio ≥ 1.2-< 2.0). MYC amplification was seen in an AFX sample of extraordinary tumor thickness of 17.5 mm (vs. median 3.25 mm for all samples). Of the 24 PDS cases, five specimen demonstrated MYC low level copy number gains. Immunohistochemically, neither the AFX nor the PDS cases showed MYC protein expression. In summary, these findings rule out that MYC amplification is a major genetic driver in the process of AFX or PDS tumorigenesis. However, MYC amplification may occur as a late event during AFX development and hence might only be detectable in advanced, thick lesions.

Comparison of various methods to analyse toxic effects in human skin explants: Rediscovery of TTC assay

Skin explants are a suitable model which can replace dermatological experiments on animals or human volunteers. In this study, we searched for a fast, cheap and reproducible method for screening skin explant viability after treatment with UVA radiation or/and chemical agents. We compared frequently used methods: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), neutral red (NR) and lactate dehydrogenase (LDH) activity assay with a rarely used 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) assay for the evaluation of UVA radiation and/or chlorpromazine and 8-methoxypsoralen effect as model agents. Histological analysis of skin explants was also performed by a simple haematoxylin-eosin method. Only the TTC assay was able to show the toxicity of model agents in a dose- and concentration-dependent manner. LDH assay was partially able to demonstrate results comparable to the TTC method, however, the agents' effect was less pronounced. The MTT and NR assays completely failed in the evaluation. Haematoxylin-eosin staining showed discrete structural changes in samples treated with UVA alone and CPZ+UVA, but only after 48h. Therefore, the method is not useful for screening of toxic or phototoxic effects either. In conclusion, the TTC assay was the most suitable for the evaluation of toxicity or phototoxicity in ex vivo skin.

Quantifying phenotype-environment matching in the protected Kerry spotted slug (Mollusca: Gastropoda) using digital photography: exposure to UV radiation determines cryptic colour morphs

BACKGROUND

Animal colours and patterns commonly play a role in reducing detection by predators, social signalling or increasing survival in response to some other environmental pressure. Different colour morphs can evolve within populations exposed to different levels of predation or environmental stress and in some cases can arise within the lifetime of an individual as the result of phenotypic plasticity. Skin pigmentation is variable for many terrestrial slugs (Mollusca: Gastropoda), both between and within species. The Kerry spotted slug Geomalacus maculosus Allman, an EU protected species, exhibits two distinct phenotypes: brown individuals occur in forested habitats whereas black animals live in open habitats such as blanket bog. Both colour forms are spotted and each type strongly resembles the substrate of their habitat, suggesting that G. maculosus possesses camouflage.

RESULTS

Analysis of digital images of wild slugs demonstrated that each colour morph is strongly and positively correlated with the colour properties of the background in each habitat but not with the substrate of the alternative habitats, suggesting habitat-specific crypsis. Experiments were undertaken on laboratory-reared juvenile slugs to investigate whether ultraviolet (UV) radiation or diet could induce colour change. Exposure to UV radiation induced the black (bog) phenotype whereas slugs reared in darkness did not change colour. Diet had no effect on juvenile colouration. Examination of skin tissue from specimens exposed to either UV or dark treatments demonstrated that UV-exposed slugs had significantly higher concentrations of black pigment in their epithelium.

CONCLUSIONS

These results suggest that colour dimorphism in G. maculosus is an example of phenotypic plasticity which is explained by differential exposure to UV radiation. Each resulting colour morph provides incidental camouflage against the different coloured substrate of each habitat. This, to our knowledge, is the first documented example of colour change in response to UV radiation in a terrestrial mollusc. Pigmentation appears to be correlated with a number of behavioural traits in G. maculosus, and we suggest that understanding melanisation in other terrestrial molluscs may be useful in the study of pestiferous and invasive species. The implications of colour change for G. maculosus conservation are also discussed.

Pre-diagnostic leukocyte mitochondrial DNA copy number and skin cancer risk

No previous study has examined the association between mitochondrial DNA copy number (mtCN) and skin cancer risk prospectively. We examined the associations between peripheral blood leukocytes mtCN level and the risks of skin cancers in a case-control study nested within the Nurses' Health Study of non-Hispanic White women, including 272 melanoma cases and 293 controls, 508 squamous cell carcinoma (SCC) cases and 550 controls, and 515 basal cell carcinoma (BCC) cases and 536 controls. Relative mtCN in peripheral blood leukocytes was measured by quantitative PCR-based assay. Unconditional logistic regression models were used to examine the associations between mtCN and skin cancer risks. Compared with those with high mtCN, the risk for melanoma was 1.06 [95% confidence interval (CI) = 0.70-1.62] in the median group and 1.19 (95% CI = 0.78-1.81) for the low group. There was suggestive evidence that increased risk for melanoma was apparent among low constitutional susceptibility group [odds ratio (OR)low versus high = 1.80, 95% CI = 0.95-3.39, P for trend = 0.07, P for interaction = 0.06]. The increased risk of melanoma was also apparent among high cumulative UV exposure group (ORlow versus high = 3.40, 95% CI = 1.46-7.92, P for trend = 0.004, P for interaction = 0.01). For non-melanoma skin cancers, compared with high-mtCN group, low-mtCN group had an increased risk for SCC (OR = 1.26, 95% CI = 0.93-1.71) and BCC (OR = 1.35; 95% CI = 1.00-1.82). Because some of the associations were marginally significant, the results only provided suggestive evidence. Further studies are warranted to replicate these findings and better understand the underlying mechanisms.

Genotoxic changes in peripheral lymphocytes after therapeutic exposure to crude coal tar and ultraviolet radiation

AIMS

Goeckerman therapy is based on combined exposure to UV radiation (UVA, UVB) and crude coal tar (PAHs). Some indicators suggest a genotoxic hazard, however, the level of genotoxic risk of the therapy has not yet been investigated sufficiently. This study aims to assesss the genotoxic risk.

METHODS

The studied group consisted of patients with chronic stable plaque psoriasis treated by Goeckerman therapy (n = 29). Heparin-treated peripheral blood samples were collected one day before the first treatment and immediately after the last procedure. The lymphocytes were isolated from the blood. The level of genotoxicity was evaluated using an alkaline version of the Comet assay which detects DNA single strand breaks (DNA-SSBs), a neutral version of the Comet assay which detects DNA double strand breaks (DNA-DSBs), and using chromosomal aberrations.

RESULTS

The level of DNA-SSBs increased insignificantly (median; Q1-Q3): 1.4 (0.4; 0.1-1.4) vs. 2.5 (0.6; 0.3-2.7) %tDNA (P = 0.11) and the level of DNA-DSBs increased significantly: 7.8 (6.5; 3.4-10.5) vs. 20.7 (19.3; 14.2-24.6) % DNA (P < 0.001). The total number of aberrated cells (P < 0.001) and structurally aberrated cells (P < 0.001) increased significantly.

CONCLUSION

The elevated levels of the DNA-DSBs and the chromosomal aberrations in the peripheral lymphocytes indicated a genotoxic hazard. However, the elevated level of the chromosomal abnormalities was below the upper level of the reference range for healthy Czech adults. While, the genotoxic risk appears to be low, Goeckerman treatment represents a further contribution to the lifetime load of genotoxic factors.

Hesperidin Attenuates Ultraviolet B-Induced Apoptosis by Mitigating Oxidative Stress in Human Keratinocytes

Human skin cells undergo pathophysiological processes via generation of reactive oxygen species (ROS) upon excessive exposure to ultraviolet B (UVB) radiation. This study investigated the ability of hesperidin (C₂₈H₃₄O₁₅) to prevent apoptosis due to oxidative stress generated through UVB-induced ROS. Hesperidin significantly scavenged ROS generated by UVB radiation, attenuated the oxidation of cellular macromolecules, established mitochondrial membrane polarization, and prevented the release of cytochrome c into the cytosol. Hesperidin downregulated expression of caspase-9, caspase-3, and Bcl-2-associated X protein, and upregulated expression of B-cell lymphoma 2. Hesperidin absorbed wavelengths of light within the UVB range. In summary, hesperidin shielded human keratinocytes from UVB radiation-induced damage and apoptosis via its antioxidant and UVB absorption properties.

Genome Resequencing Identifies Unique Adaptations of Tibetan Chickens to Hypoxia and High-Dose Ultraviolet Radiation in High-Altitude Environments

Tibetan chicken, unlike their lowland counterparts, exhibit specific adaptations to high-altitude conditions. The genetic mechanisms of such adaptations in highland chickens were determined by resequencing the genomes of four highland (Tibetan and Lhasa White) and four lowland (White Leghorn, Lindian, and Chahua) chicken populations. Our results showed an evident genetic admixture in Tibetan chickens, suggesting a history of introgression from lowland gene pools. Genes showing positive selection in highland populations were related to cardiovascular and respiratory system development, DNA repair, response to radiation, inflammation, and immune responses, indicating a strong adaptation to oxygen scarcity and high-intensity solar radiation. The distribution of allele frequencies of nonsynonymous single nucleotide polymorphisms between highland and lowland populations was analyzed using chi-square test, which showed that several differentially distributed genes with missense mutations were enriched in several functional categories, especially in blood vessel development and adaptations to hypoxia and intense radiation. RNA sequencing revealed that several differentially expressed genes were enriched in gene ontology terms related to blood vessel and respiratory system development. Several candidate genes involved in the development of cardiorespiratory system (FGFR1, CTGF, ADAM9, JPH2, SATB1, BMP4, LOX, LPR, ANGPTL4, and HYAL1), inflammation and immune responses (AIRE, MYO1F, ZAP70, DDX60, CCL19, CD47, JSC, and FAS), DNA repair, and responses to radiation (VCP, ASH2L, and FANCG) were identified to play key roles in the adaptation to high-altitude conditions. Our data provide new insights into the unique adaptations of highland animals to extreme environments.

Comparative transcriptomic analysis revealed adaptation mechanism of Phrynocephalus erythrurus, the highest altitude Lizard living in the Qinghai-Tibet Plateau

BACKGROUND

Organisms living at high altitudes must overcome three major environmental challenges: hypoxia, cold, and intense UV radiation. The molecular mechanisms that enable these challenges to be overcome have mainly been studied in endothermic organisms; relatively little attention has been paid to poikilothermic species. Here, we present deep transcriptome sequencing in two closely related lizards, the high altitude-dwelling Phrynocephalus erythrurus and the lowland-dwelling P. putjatia, to identify candidate genes under positive selection and to explore the convergent evolutionary adaptation of poikilothermic animals to high altitude life.

RESULTS

More than 70 million sequence reads were generated for each species via Illumina sequencing. De novo assembly produced 56,845 and 63,140 transcripts for P. erythrurus and P. putjatia, respectively. P. erythrurus had higher Ka/Ks ratios than P. putjatia, implying an accelerated evolutionary rate in the high altitude lizard lineage. 206 gene ontology (GO) categories with accelerated evolutionary rates and 43 candidate positively selected genes were detected along the P. erythrurus lineage. Some of these GO categories have functions associated with responses to hypoxia, energy metabolism and responses to UV damage. We also found that the high-altitude ranid frog R. kukunoris had higher Ka/Ks ratios than the closely related low-altitude frog R. chensinensis, and that the functional categories with accelerated evolutionary rates in R. kukunoris overlapped extensively with those detected along the P. erythrurus lineage.

CONCLUSIONS

The mechanisms of high altitude adaptation in P. erythrurus were tentatively inferred. By comparing two pairs of low- and high-altitude poikilothermic species, we found that similar functional categories had undergone positive selection in high altitude-dwelling Phrynocephalus and Rana lineages, indicating that similar mechanisms of adaptation to high altitude might have evolved in both genera. Our findings provide important guidance for future functional studies on high altitude adaptation in poikilothermic animals.

Cell death in human articular chondrocyte: a morpho-functional study in micromass model

Chondrocyte death and loss of extracellular matrix are the central features in articular cartilage degeneration during osteoarthritis pathogenesis. Cartilage diseases and, in particular, osteoarthritis are widely correlated to apoptosis but, chondrocytes undergoing apoptosis "in vivo" more often display peculiar features that correspond to a distinct process of programmed cell death termed "chondroptosis". Programmed cell death of primary human chondrocyte has been here investigated in micromasses, a tridimensional culture model, that represents a convenient means for studying chondrocyte biology. Cell death has been induced by different physical or chemical apoptotic agents, such as UVB radiation, hyperthermia and staurosporine delivered at both 1 and 3 weeks maturation. Conventional electron microscopy was used to analyse morphological changes. Occurrence of DNA fragmentation and caspase involvement were also investigated. At Transmission Electron Microscopy, control cells appear rounding or slightly elongated with plurilobated nucleus and diffusely dispersed chromatin. Typically UVB radiation and staurosporine induce chromatin apoptotic features, while hyperthermia triggers the "chondroptotic" phenotype. A weak TUNEL positivity appears in control, correlated to the well known cell death patterns occurring along cartilage differentiation. UVB radiation produces a strong positivity, mostly localized at the micromass periphery. After hyperthermia a higher number of fluorescent nuclei appears, in particular at 3 weeks. Staurosporine evidences a diffuse, but reduced, positivity. Therefore, DNA fragmentation is a common pattern in dying chondrocytes, both in apoptotic and "chondroptotic" cells. Moreover, all triggers induce caspase pathway activation, even if to a different extent, suggesting a fundamental role of apoptotic features, in chondrocyte cell death.

Real-time PCR Tests in Dutch Exotic Mosquito Surveys; Implementation of Aedes aegypti and Aedes albopictus Identification Tests, and the Development of Tests for the Identification of Aedes atropalpus and Aedes japonicus japonicus (Diptera: Culicidae)

Since 2009, The Netherlands Food and Consumer Product Safety Authority carries out surveys focusing on, amongst others, the presence of invasive mosquito species (IMS). Special attention is given to exotic container-breeding Aedes species Aedes aegypti (L.), Aedes albopictus (Skuse), Aedes atropalpus (Coquillett), and Aedes japonicus japonicus (Theobald). This study describes the implementation of real-time PCR tests described by Hill et al. (2008) for the identification of Ae. aegypti and Ae. albopictus, and the development of two novel real-time PCR tests for the identification of Ae. atropalpus and Ae. j. japonicus. Initial test showed that optimization of elements of the Ae. aegypti and Ae. albopictus tests was needed. Method validation tests were performed to determine if the implemented and newly developed tests are fit for routine diagnostics. Performance criteria of analytical sensitivity, analytical specificity, selectivity, repeatability, and reproducibility were determined. In addition, experiments were performed to determine the influence of environmental conditions on the usability of DNA extracted from mosquito specimens trapped in BG-Sentinel traps. The real-time PCR tests were demonstrated to be sensitive, specific, repeatable, reproducible, and are less prone to false negative results compared to partial cytochrome c oxidase I gene sequencing owing to the DNA fragmentation caused by environmental influences.

Exploring the genetic basis of adaptation to high elevations in reptiles: a comparative transcriptome analysis of two toad-headed agamas (genus Phrynocephalus)

High elevation adaptation offers an excellent study system to understand the genetic basis of adaptive evolution. We acquired transcriptome sequences of two closely related lizards, Phrynocephalus przewalskii from low elevations and P. vlangalii from high elevations. Within a phylogenetic framework, we compared their genomic data along with green anole, chicken and Chinese softshell turtle, and identified candidate genes and functional categories that are potentially linked to adaptation to high elevation environments. More than 100 million sequence reads were generated for each species via Illumina sequencing. A de novo assembly produced 70,919 and 62,118 transcripts for P. przewalskii and P. vlangalii, respectively. Based on a well-established reptile phylogeny, we detected 143 positively selected genes (PSGs) along the P. vlangalii lineage from the 7,012 putative orthologs using a branch-site model. Furthermore, ten GO categories and one KEGG pathway that are over-represented by PSGs were recognized. In addition, 58 GO categories were revealed to have elevated evolutionary rates along the P. vlangalii lineage relative to P. przewalskii. These functional analyses further filter out PSGs that are most likely involved in the adaptation process to high elevations. Among them, ADAM17, MD, and HSP90B1 likely contributed to response to hypoxia, and POLK likely contributed to DNA repair. Many other candidate genes involved in gene expression and metabolism were also identified. Genome-wide scan for candidate genes may serve as the first step to explore the genetic basis of high elevation adaptation. Detailed comparative study and functional verification are needed to solidify any conclusions. High elevation adaptation requires coordinated changes in multiple genes that involve various physiological and biochemical pathways; we hope that our genetic studies will provide useful directions for future physiological or molecular studies in reptiles as well as other poikilothermic species.

Fucodiphlorethol G Purified from Ecklonia cava Suppresses Ultraviolet B Radiation-Induced Oxidative Stress and Cellular Damage

Fucodiphlorethol G (6’-[2,4-dihydroxy-6-(2,4,6-trihydroxyphenoxy)phenoxy]biphenyl-2,2’,4,4’,6-pentol) is a compound purified from Ecklonia cava, a brown alga that is widely distributed offshore of Jeju Island. This study investigated the protective effects of fucodiphlorethol G against oxidative damage-mediated apoptosis induced by ultraviolet B (UVB) irradiation. Fucodiphlorethol G attenuated the generation of 2, 2-diphenyl-1-picrylhydrazyl radicals and intracellular reactive oxygen species in response to UVB irradiation. Fucodiphlorethol G suppressed the inhibition of human keratinocyte growth by UVB irradiation. Additionally, the wavelength of light absorbed by fucodiphlorethol G was close to the UVB spectrum. Fucodiphlorethol G reduced UVB radiation-induced 8-isoprostane generation and DNA fragmentation in human keratinocytes. Moreover, fucodiphlorethol G reduced UVB radiation-induced loss of mitochondrial membrane potential, generation of apoptotic cells, and active caspase-9 expression. Taken together, fucodiphlorethol G protected human keratinocytes against UVB radiation-induced cell damage and apoptosis by absorbing UVB radiation and scavenging reactive oxygen species.

The formation of DNA single-strand breaks and alkali-labile sites in human blood lymphocytes exposed to 365-nm UVA radiation

The potency of UVA radiation, representing 90% of solar UV light reaching the earth's surface, to induce human skin cancer is the subject of continuing controversy. This study was undertaken to investigate the role of reactive oxygen species in DNA damage produced by the exposure of human cells to UVA radiation. This knowledge is important for better understanding of UV-induced carcinogenesis. We measured DNA single-strand breaks and alkali-labile sites in human lymphocytes exposed ex vivo to various doses of 365-nm UV photons compared to X-rays and hydrogen peroxide using the comet assay. We demonstrated that the UVA-induced DNA damage increased in a linear dose-dependent manner. The rate of DNA single-strand breaks and alkali-labile sites after exposure to 1J/cm(2) was similar to the rate induced by exposure to 1 Gy of X-rays or 25 μM hydrogen peroxide. The presence of either the hydroxyl radical scavenger dimethyl sulfoxide or the singlet oxygen quencher sodium azide resulted in a significant reduction in the UVA-induced DNA damage, suggesting a role for these reactive oxygen species in mediating UVA-induced DNA single-strand breaks and alkali-labile sites. We also showed that chromatin relaxation due to hypertonic conditions resulted in increased damage in both untreated and UVA-treated cells. The effect was the most significant in the presence of 0.5M Na(+), implying a role for histone H1. Our data suggest that the majority of DNA single-strand breaks and alkali-labile sites after exposure of human lymphocytes to UVA are produced by reactive oxygen species (the hydroxyl radical and singlet oxygen) and that the state of chromatin may substantially contribute to the outcome of such exposures.

Sensitivity and specificity of the empirical lymphocyte genome sensitivity (LGS) assay: implications for improving cancer diagnostics

Lymphocyte responses from 208 individuals: 20 with melanoma, 34 with colon cancer, and 4 with lung cancer (58), 18 with suspected melanoma, 28 with polyposis, and 10 with COPD (56), and 94 healthy volunteers were examined. The natural logarithm of the Olive tail moment (OTM) was plotted for exposure to UVA through 5 different agar depths (100 cell measurements/depth) and analyzed using a repeated measures regression model. Responses of patients with cancer plateaued after treatment with different UVA intensities, but returned toward control values for healthy volunteers. For precancerous conditions and suspected cancers, intermediate responses occurred. ROC analysis of mean log OTMs, for cancers plus precancerous/suspect conditions vs. controls, cancer vs. precancerous/suspect conditions plus controls, and cancer vs. controls, gave areas under the curve of 0.87, 0.89, and 0.93, respectively (P<0.001). Optimization allowed test sensitivity or specificity to approach 100% with acceptable complementary measures. This modified comet assay could represent a stand-alone test or an adjunct to other investigative procedures for detecting cancer.

Characterization of a human skin equivalent model to study the effects of ultraviolet B radiation on keratinocytes

The incidences of skin cancers resulting from chronic ultraviolet radiation (UVR) exposure are on the incline in both Australia and globally. Hence, the cellular and molecular pathways that are associated with UVR-induced photocarcinogenesis need to be urgently elucidated, in order to develop more robust preventative and treatment strategies against skin cancers. In vitro investigations into the effects of UVR (in particular, the highly mutagenic UVB wavelength) have, to date, mainly involved the use of cell culture and animal models. However, these models possess biological disparities to native skin, which, to some extent, have limited their relevance to the in vivo situation. To address this, we characterized a three-dimensional, tissue-engineered human skin equivalent (HSE) model (consisting of primary human keratinocytes cultured on a dermal-derived scaffold) as a representation of a more physiologically relevant platform to study keratinocyte responses to UVB. Significantly, we demonstrate that this model retains several important epidermal properties of native skin. Moreover, UVB irradiation of the HSE constructs was shown to induce key markers of photodamage in the HSE keratinocytes, including the formation of cyclobutane pyrimidine dimers, the activation of apoptotic pathways, the accumulation of p53, and the secretion of inflammatory cytokines. Importantly, we also demonstrate that the UVB-exposed HSE constructs retain the capacity for epidermal repair and regeneration after photodamage. Together, our results demonstrate the potential of this skin equivalent model as a tool to study various aspects of the acute responses of human keratinocytes to UVB radiation damage.

Cell-type-specific roles for COX-2 in UVB-induced skin cancer

In human tumors, and in mouse models, cyclooxygenase-2 (COX-2) levels are frequently correlated with tumor development/burden. In addition to intrinsic tumor cell expression, COX-2 is often present in fibroblasts, myofibroblasts and endothelial cells of the tumor microenvironment, and in infiltrating immune cells. Intrinsic cancer cell COX-2 expression is postulated as only one of many sources for prostanoids required for tumor promotion/progression. Although both COX-2 inhibition and global Cox-2 gene deletion ameliorate ultraviolet B (UVB)-induced SKH-1 mouse skin tumorigenesis, neither manipulation can elucidate the cell type(s) in which COX-2 expression is required for tumorigenesis; both eliminate COX-2 activity in all cells. To address this question, we created Cox-2(flox/flox) mice, in which the Cox-2 gene can be eliminated in a cell-type-specific fashion by targeted Cre recombinase expression. Cox-2 deletion in skin epithelial cells of SKH-1 Cox-2(flox/flox);K14Cre(+) mice resulted, following UVB irradiation, in reduced skin hyperplasia and increased apoptosis. Targeted epithelial cell Cox-2 deletion also resulted in reduced tumor incidence, frequency, size and proliferation rate, altered tumor cell differentiation and reduced tumor vascularization. Moreover, Cox-2(flox/flox);K14Cre(+) papillomas did not progress to squamous cell carcinomas. In contrast, Cox-2 deletion in SKH-1 Cox-2(flox/flox); LysMCre(+) myeloid cells had no effect on UVB tumor induction. We conclude that (i) intrinsic epithelial COX-2 activity plays a major role in UVB-induced skin cancer, (ii) macrophage/myeloid COX-2 plays no role in UVB-induced skin cancer and (iii) either there may be another COX-2-dependent prostanoid source(s) that drives UVB skin tumor induction or there may exist a COX-2-independent pathway(s) to UVB-induced skin cancer.

Vitamin D and cardiovascular disease: is the evidence solid?

Vitamin D deficiency, prevalent in 30-50% of adults in developed countries, is largely due to inadequate cutaneous production that results from decreased exposure to sunlight, and to a lesser degree from low dietary intake of vitamin D. Serum levels of 25-hydroxyvitamin D (25-OH D) <20 ng/mL indicate vitamin D deficiency and levels >30 ng/mL are considered optimal. While the endocrine functions of vitamin D related to bone metabolism and mineral ion homoeostasis have been extensively studied, robust epidemiological evidence also suggests a close association between vitamin D deficiency and cardiovascular morbidity and mortality. Experimental studies have demonstrated novel actions of vitamin D metabolites on cardiomyocytes, and endothelial and vascular smooth muscle cells. Low 25-OH D levels are associated with left ventricular hypertrophy, vascular dysfunction, and renin-angiotensin system activation. Despite a large body of experimental, cross-sectional, and prospective evidence implicating vitamin D deficiency in the pathogenesis of cardiovascular disease, a causal relationship remains to be established. Moreover, the cardiovascular benefits of normalizing 25-OH D levels in those without renal disease or hyperparathyroidism have not been established, and questions of an epiphenomenon where vitamin D status merely reflects a classic risk burden have been raised. Randomized trials of vitamin D replacement employing cardiovascular endpoints will provide much needed evidence for determining its role in cardiovascular protection.

Differential modulation of inflammatory markers in plasma and skin after single exposures to UVA or UVB radiation in vivo

BACKGROUND

Solar light generates inflammatory responses in exposed skin. These effects are generally attributed to UVB light. However, skin is expose d to a huge quantum of UVA photons as UVA is a predominant part of sunlight and the radiation used in tanning beds. We examined the effects of a single exposure to UVA and UVB wavebands on cytokine levels in skin and plasma, myeloperoxidase (MPO) activity, expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) in skin.

METHODS

Hairless mice were irradiated with either UVA (10 or 20 J/cm²) or UVB (200 or 800 mJ/cm²). The effects were assessed after 4/24 h. Plasma cytokine levels were evaluated using a Bio-Plex cytokine assay. Cytokine, iNOS and COX-2 levels in skin were determined by Western blot. Skin MPO activity was monitored spectrophotometrically.

RESULTS

UVB induced up-regulation of interleukin-1β (IL-1β) and interleukin-6 (IL-6) and decrease in interleukin-10 (IL-10) mainly after 4 h. In contrast, UVA caused increase in levels of tumor necrosis factor-alpha (TNF-α) and IL-6 after 4 h and up-regulated IL-10 and interleukin-12 (IL-12) after 24 h. The increase in MPO activity from infiltrated leucocytes was observed only in UVB irradiated animals. iNOS was up-regulated 4 h after UVA and UVB treatment. No significant effect on COX-2 expression was detected.

CONCLUSIONS

UVA and UVB light affected several inflammatory markers. For individual waveband, changes in plasma parameters did not correlate with those in skin. Thus evaluation of plasma samples cannot simply be replaced by determination in skin specimens and vice versa.

The effect of ultraviolet radiation on the transforming growth factor beta 1/Smads pathway and p53 in actinic keratosis and normal skin

Ultraviolet (UV) radiation is considered to be essential for the progression of actinic keratosis (AK) to squamous cell carcinoma (SCC); however, the mechanisms have not been fully elucidated. To understand this process, the effects of UV radiation on the transforming growth factor beta 1 (TGFβ1)/Smads pathway and p53 in normal skin and AK were studied. Normal human skin and AK tissues were cultured and divided into the following four groups according to the UV radiation dose: 0 (control group), 5, 10, and 20 J/cm2. The tissues were radiated for four consecutive days; 24 h after radiation, the tissues were collected for investigation. Compared with the control group, greater proliferative inhibition and apoptosis were induced by UV radiation in normal skin than AK. The expression of TGFβ1, Smad7, and p53 was increased in AK and normal skin, while the level of TβRII was decreased. Smad2 was reduced in AK only. The expressions of TβRI, Smad3, and Smad4 were not significantly changed. The results demonstrated that although p53 was induced, suppression of the TGFβ1/Smads pathway by UV radiation might contribute to the progression of AK to SCC.

Multi-chromatic control of mammalian gene expression and signaling

The emergence and future of mammalian synthetic biology depends on technologies for orchestrating and custom tailoring complementary gene expression and signaling processes in a predictable manner. Here, we demonstrate for the first time multi-chromatic expression control in mammalian cells by differentially inducing up to three genes in a single cell culture in response to light of different wavelengths. To this end, we developed an ultraviolet B (UVB)-inducible expression system by designing a UVB-responsive split transcription factor based on the Arabidopsis thaliana UVB receptor UVR8 and the WD40 domain of COP1. The system allowed high (up to 800-fold) UVB-induced gene expression in human, monkey, hamster and mouse cells. Based on a quantitative model, we determined critical system parameters. By combining this UVB-responsive system with blue and red light-inducible gene control technology, we demonstrate multi-chromatic multi-gene control by differentially expressing three genes in a single cell culture in mammalian cells, and we apply this system for the multi-chromatic control of angiogenic signaling processes. This portfolio of optogenetic tools enables the design and implementation of synthetic biological networks showing unmatched spatiotemporal precision for future research and biomedical applications.

Impact of external forces on cyanophage-host interactions in aquatic ecosystems

Cyanobacterial (algal) blooms have by convention been attributed to the excessive level of nutrients from pollution and runoff, which promotes the rapid growth and multiplication of cyanobacteria or algae. The cyanophage (virus) is the natural predator of cyanobacteria (the host). The aim of this review is to unveil certain pressures that disrupt cyanophage-host interactions and the formation of cyanobacterial blooms. This review focuses principally on the impact of greenhouse gases, ozone depletion, solar ultraviolet radiation (SUR) and the role of recently discovered virophages, which coexist with and in turn are the natural predator of phages. The key findings are that the increase in SUR, the mutation of cyanophages and cyanobacteria, along with changing nutrient levels, have combined with virophages to impede cyanophage-host interactions and the resultant viral infection and killing of the cyanobacterial cell, which is a necessary step in controlling cyanobacterial blooms. Consider this a 'call to action' for researchers interested in corrective action aimed at evolving aquatic ecosystems.