Ultraviolet radiation: DNA damage, repair, and human disorders

Impact of double-strand breaks induced by uv radiation on neuroinflammation and neurodegenerative disorders

Exposure to UV affects the development and growth of a wide range of organisms. Nowadays, researchers are focusing on the impact of UV radiation and its underlying molecular mechanisms, as well as devising strategies to mitigate its harmful effects. Different forms of UV radiation, their typical exposure effects, the impact of UV on DNA integrity, and the deterioration of genetic material are discussed in this review; furthermore, we also review the effects of UV radiation that affect the biological functions of the organisms. Subsequently, we address the processes that aid organisms in navigating the damage in genetic material, neuroinflammation, and neurodegeneration brought on by UV-mediated double-strand breaks. To emphasize the molecular pathways, we conclude the review by going over the animal model studies that highlight the genes and proteins that are impacted by UV radiation.

Role of c-Fos in DNA damage repair

c-Fos, a member of the immediate early gene, serves as a widely used marker of neuronal activation induced by various types of brain damage. In addition, c-Fos is believed to play a regulatory role in DNA damage repair. This paper reviews the literature on c-Fos' involvement in the regulation of DNA damage repair and indicates that genes of the Fos family can be induced by various forms of DNA damage. In addition, cells lacking c-Fos have difficulties in DNA repair. c-Fos is involved in tumorigenesis and progression as a proto-oncogene that maintains cancer cell survival, which may also be related to DNA repair. c-Fos may impact the repair of DNA damage by regulating the expression of downstream proteins, including ATR, ERCC1, XPF, and others. Nonetheless, the underlying mechanisms necessitate further exploration.

Photolytic splitting of homodimeric quinone-derived oxetanes studied by ultrafast transient absorption spectroscopy and quantum chemistry

The photoinduced cycloreversion of oxetane derivatives is of considerable biological interest since these compounds are involved in the photochemical formation and repair of the highly mutagenic pyrimidine (6-4) pyrimidone DNA photoproducts ((6-4)PPs). Previous reports have dealt with the photoreactivity of heterodimeric oxetanes composed mainly of benzophenone (BP) and thymine (Thy) or uracil (Ura) derivatives. However, these models are far from the non-isolable Thy〈º〉Thy dimers, which are the real precursors of (6-4)PPs. Thus, we have synthesized two chemically stable homodimeric oxetanes through the Paternò-Büchi reaction between two identical enone units, i.e. 1,4-benzoquinone (BQ) and 1,4-naphthoquinone (NQ), that led to formation of BQ-Ox and NQ-Ox, respectively. Their photoreactivity has been studied by means of steady-state photolysis and transient absorption spectroscopy from the femtosecond to the microsecond time scale. Thus, photolysis of BQ-Ox and NQ-Ox led to formation of the monomeric BQ or NQ, respectively, through ring opening in a "non-adiabatic" process. Accordingly, the transient absorption spectra of the triplet excited quinones (3BQ* and 3NQ*) were not observed as a result of direct photolysis of the quinone-derived oxetanes. In the case of NQ-Ox, a minor signal corresponding to 3NQ* was detected; its formation was ascribed to minor photodegradation of the oxetane during acquisitions of the spectra during the laser experiments. These results are supported by computational analyses based on density functional theory and multiconfigurational quantum chemistry (CASSCF/CASPT2); here, an accessible conical intersection between the ground and excited singlet states has been characterized as the main structure leading to deactivation of excited BQ-Ox or NQ-Ox. This behavior contrasts with those previously observed for heterodimeric thymine-derived oxetanes, where a certain degree of ring opening into the excited triplet state is observed.

Integrative analysis of RNA-sequencing and microarray for the identification of adverse effects of UVB exposure on human skin

Background

Ultraviolet B (UVB) from sunlight represents a major environmental factor that causes toxic effects resulting in structural and functional cutaneous abnormalities in most living organisms. Although numerous studies have indicated the biological mechanisms linking UVB exposure and cutaneous manifestations, they have typically originated from a single study performed under limited conditions.

Methods

We accessed all publicly accessible expression data of various skin cell types exposed to UVB, including skin biopsies, keratinocytes, and fibroblasts. We performed biological network analysis to identify the molecular mechanisms and identify genetic biomarkers.

Results

We interpreted the inflammatory response and carcinogenesis as major UVB-induced signaling alternations and identified three candidate biomarkers (IL1B, CCL2, and LIF). Moreover, we confirmed that these three biomarkers contribute to the survival probability of patients with cutaneous melanoma, the most aggressive and lethal form of skin cancer.

Conclusion

Our findings will aid the understanding of UVB-induced cutaneous toxicity and the accompanying molecular mechanisms. In addition, the three candidate biomarkers that change molecular signals due to UVB exposure of skin might be related to the survival rate of patients with cutaneous melanoma.

Shedding light on cellular dynamics: the progress in developing photoactivated fluorophores

Photoactivated fluorophores (PAFs) are highly effective imaging tools that exhibit a removal of caging groups upon light excitation, resulting in the restoration of their bright fluorescence. This unique property allows for precise control over the spatiotemporal aspects of small molecule substances, making them indispensable for studying protein labeling and small molecule signaling within live cells. In this comprehensive review, we explore the historical background of this field and emphasize recent advancements based on various reaction mechanisms. Additionally, we discuss the structures and applications of the PAFs. We firmly believe that the development of more novel PAFs will provide powerful tools to dynamically investigate cells and expand the applications of these techniques into new domains.

Antibacterial micro/nanomotors: advancing biofilm research to support medical applications

Multi-drug resistant (MDR) bacterial infections are gradually increasing in the global scope, causing a serious burden to patients and society. The formation of bacterial biofilms, which is one of the key reasons for antibiotic resistance, blocks antibiotic penetration by forming a physical barrier. Nano/micro motors (MNMs) are micro-/nanoscale devices capable of performing complex tasks in the bacterial microenvironment by transforming various energy sources (including chemical fuels or external physical fields) into mechanical motion or actuation. This autonomous movement provides significant advantages in breaking through biological barriers and accelerating drug diffusion. In recent years, MNMs with high penetrating power have been used as carriers of antibiotics to overcome bacterial biofilms, enabling efficient drug delivery and improving the therapeutic effectiveness of MDR bacterial infections. Additionally, non-antibiotic antibacterial strategies based on nanomaterials, such as photothermal therapy and photodynamic therapy, are continuously being developed due to their non-invasive nature, high effectiveness, and non-induction of resistance. Therefore, multifunctional MNMs have broad prospects in the treatment of MDR bacterial infections. This review discusses the performance of MNMs in the breakthrough and elimination of bacterial biofilms, as well as their application in the field of anti-infection. Finally, the challenges and future development directions of antibacterial MNMs are introduced.

DNA Damage Induced by T-2 Mycotoxin in Human Skin Fibroblast Cell Line-Hs68

T-2 mycotoxin is the most potent representative of the trichothecene group A and is produced by various Fusarium species, including F. sporotrichioides, F. poae, and F. acuminatum. T-2 toxin has been reported to have toxic effects on various tissues and organs, and humans and animals alike suffer a variety of pathological conditions after consumption of mycotoxin-contaminated food. The T-2 toxin's unique feature is dermal toxicity, characterized by skin inflammation. In this in vitro study, we investigated the molecular mechanism of T-2 toxin-induced genotoxicity in the human skin fibroblast-Hs68 cell line. For the purpose of investigation, the cells were treated with T-2 toxin in 0.1, 1, and 10 μM concentrations and incubated for 24 h and 48 h. Nuclear DNA (nDNA) is found within the nucleus of eukaryotic cells and has a double-helix structure. nDNA encodes the primary structure of proteins, consisting of the basic amino acid sequence. The alkaline comet assay results showed that T-2 toxin induces DNA alkali-labile sites. The DNA strand breaks in cells, and the DNA damage level is correlated with the increasing concentration and time of exposure to T-2 toxin. The evaluation of nDNA damage revealed that exposure to toxin resulted in an increasing lesion frequency in Hs68 cells with HPRT1 and TP53 genes. Further analyses were focused on mRNA expression changes in two groups of genes involved in the inflammatory and repair processes. The level of mRNA increased for all examined inflammatory genes (TNF, INFG, IL1A, and IL1B). In the second group of genes related to the repair process, changes in expression induced by toxin in genes-LIG3 and APEX were observed. The level of mRNA for LIG3 decreased, while that for APEX increased. In the case of LIG1, FEN, and XRCC1, no changes in mRNA level between the control and T-2 toxin probes were observed. In conclusion, the results of this study indicate that T-2 toxin shows genotoxic effects on Hs68 cells, and the molecular mechanism of this toxic effect is related to nDNA damage.

Involvement of Nucleotide Excision Repair and Rec-Dependent Pathway Genes for UV Radiation Resistance in Deinococcus irradiatisoli 17bor-2

Strain Deinococcus irradiatisoli 17bor-2 was isolated from a soil sample exposed to γ radiation at Seoul Women's University, Republic of Korea. The genus Deinococcus is a Gram-negative, coccus-shaped, and extremophilic bacterium, well renowned as being a radiation-resistant bacterium. Therefore, the mechanism behind the resistance to radiation and the gene responsible for the resistance could be helpful for detailed experimental studies with biotechnological applications. To study the involvement of genes in UV radiation resistance in strain 17bor-2, the genomic DNA of the strain was sequenced and constructed using the Pacific Biosciences RS II system. In addition, the complete genome sequence of strain 17bor-2 was annotated and interpreted using the Genomes-Expert Review (IMG-ER) system, along with Prodigal and JGI GenePRIMP analysis. The genome analysis of strain 17bor-2 revealed evidence of excinuclease UvrABC genes, which are key enzymes in the nucleotide excision repair (NER) mechanism, as well as genes from the recA-dependent and recQ pathways. The genome of strain Deinococcus irradiatisoli 17bor-2 was a circular chromosome comprising 3,052,043 bp with a GC content of 67.0%, including 2911 coding sequences (CDs), 49 tRNA genes, and 9 rRNA genes. In addition, their complete genome sequence annotation features provided evidence that radiation resistance genes play a central part in adaptation against extreme environmental conditions. In recent decades, excision repair genes have been indicated in considerable detail for both prokaryote and eukaryote resistance against UV-C radiation.

Chromosome-level Asian elephant genome assembly and comparative genomics of long-lived mammals reveal the common substitutions for cancer resistance

The naked mole rat (Heterocephalus glaber), bats (e.g., genus Myotis), and elephants (family Elephantidae) are known as long-lived mammals and are assumed to be excellent cancer antagonists. However, whether there are common genetic changes underpinning cancer resistance in these long-lived species is yet to be fully established. Here, we newly generated a high-quality chromosome-level Asian elephant (Elephas maximus) genome and identified that the expanded gene families in elephants are involved in Ras-associated and base excision repair pathways. Moreover, we performed comparative genomic analyses of 12 mammals and examined genes with signatures of positive selection in elephants, naked mole rat, and greater horseshoe bat. Residues at positively selected sites of CDR2L and ALDH6A1 in these long-lived mammals enhanced the inhibition of tumor cell migration compared to those in short-lived relatives. Overall, our study provides a new genome resource and a preliminary survey of common genetic changes in long-lived mammals.

Nonionizing Electromagnetic Irradiations; Biological Interactions, Human Safety

Human is usually exposed to environmental radiation from natural and man-made sources. Therefore, it is important to investigate the effects of exposure to environmental radiation, partly related to understanding and protecting against the risk of exposure to environmental radiation with beneficial and adverse impacts on human life. The rapid development of technologies causes a dramatic enhancement of radiation in the human environment. In this study, we address the biological effects caused by different fractions of non-ionizing electromagnetic irradiation to humans and describe possible approaches for minimizing adverse health effects initiated by radiation. The main focus was on biological mechanisms initiated by irradiation and represented protection, and safety approaches to prevent health disorders.

Metal-rich stars are less suitable for the evolution of life on their planets

Atmospheric ozone and oxygen protect the terrestrial biosphere against harmful ultraviolet (UV) radiation. Here, we model atmospheres of Earth-like planets hosted by stars with near-solar effective temperatures (5300 to 6300 K) and a broad range of metallicities covering known exoplanet host stars. We show that paradoxically, although metal-rich stars emit substantially less ultraviolet radiation than metal-poor stars, the surface of their planets is exposed to more intense ultraviolet radiation. For the stellar types considered, metallicity has a larger impact than stellar temperature. During the evolution of the universe, newly formed stars have progressively become more metal-rich, exposing organisms to increasingly intense ultraviolet radiation. Our findings imply that planets hosted by stars with low metallicity are the best targets to search for complex life on land.

Colorless, Transparent, and High-Performance Polyurethane with Intrinsic Ultraviolet Resistance and Its Anti-UV Mechanism

Polyurethane (PU) is a widely used polymer material that will age under prolonged exposure to ultraviolet (UV) light, shortening the service life. Several methods have been used to prepare the anti-UV PU, including adding nonreactive anti-UV additives, functional fillers, and biological antioxidant molecules. However, the nonreactive anti-UV additives may migrate during long-term use, the functional fillers may damage the mechanical properties and seriously reduce the light transmittance of the sample, and the biological antioxidant molecules will inevitably color the sample. To solve these problems, in this work, a benzotriazole UV absorber (Chiguard R-455) was introduced into the PU molecular chains by in situ polymerization to prepare the nonmigrating intrinsic anti-UV PU sample with high performance and colorless transparency. The anti-UV PU samples exhibit light transmittance of over 88% in the visible range and superior mechanical properties with tensile strength higher than 65 MPa and elongation at break higher than 900%. After 24 h UV irradiation (200 W, 365 nm), the tensile strength and elongation at break of pure PU sample are significantly reduced to only 8.9 and 15.8% of the original one, respectively. On the contrary, the addition of Chiguard R-455 will endow the PU sample with excellent anti-UV performance. After 24 h UV irradiation, the tensile strength (67.2 ± 1.6 MPa) and elongation at break (917.4 ± 30.0%) of PU-0.5% (the content of Chiguard R-455 is only 0.5 wt %) have changed little compared with the sample without irradiation (67.4 ± 3.5 MPa and 919.4 ± 26.5%). Additionally, the anti-UV mechanism of the PU sample is systematically studied. This work provides a feasible method for preparing colorless, transparent, high-performance, nonmigrating intrinsic UV-shielding PU samples, which can be used as a UV light-shielding material in various fields with visible and aesthetic requirements, such as protection fields and wearable products.

Light-driven textile sensors with potential application of UV detection

Smart textiles based on monitoring systems of health conditions, structural behaviour, and external environmental conditions have been presented as elegant solutions for the increasing demands of health care. In this study, cotton fabrics (CFs) were modified by a common strategy with a dipping-padding procedure using reduced graphene oxide (RGO) and a photosensitive dye, spiropyran (SP), which can detect environmental UV light. The morphology of the CF is observed by scanning electron microscopy (SEM) measurements showing that the topography structure of coatings is related to the SP content. The resistance of the textile sensors decreases after UV radiation, which may be attributed to the easier electron transmission on the coatings of the CF. With the increase of SP content, the introduction of a large amount of SP within the composites could cause discontinuous distributions of RGO in the fiber surfaces, preventing electron transmission within the coatings of the RGO. The surface wettability of the coatings and the sweat sensitivity are also studied before and after UV radiation.

Transepithelial transport and cellular mechanisms of food-derived antioxidant peptides

Considering the involvement of oxidative stress in the etiology of many non-communicable diseases, food-derived antioxidant peptides (FDAPs) are strong candidates for nutraceutical development for disease prevention and management. This paper reviews current evidence on the transepithelial transport and cellular mechanisms of antioxidant activities of FDAPs. Several FDAPs have multiple health benefits such as anti-inflammatory and anti-photoaging activities, in addition to antioxidant properties through which they protect cellular components from oxidative damage. Some FDAPs have been shown to permeate the intestinal epithelium, which could facilitate their bioavailability and physiological bioactivities. Molecular mechanisms of FDAPs include suppression of oxidative stress as evidenced by reduction in intracellular reactive oxygen species production, lipid peroxidation and apoptotic protein activation as well as increase in antioxidant defense mechanisms (enzymatic and non-enzymatic). Since many FDAPs have demonstrated promising antioxidant activity, future investigation should focus on further elucidation of molecular mechanisms and human studies to explore their practical application for the prevention and management of oxidative stress-related diseases.

A second DNA binding site on RFC facilitates clamp loading at gapped or nicked DNA

Clamp loaders place circular sliding clamp proteins onto DNA so that clamp-binding partner proteins can synthesize, scan, and repair the genome. DNA with nicks or small single-stranded gaps are common clamp-loading targets in DNA repair, yet these substrates would be sterically blocked given the known mechanism for binding of primer-template DNA. Here, we report the discovery of a second DNA binding site in the yeast clamp loader replication factor C (RFC) that aids in binding to nicked or gapped DNA. This DNA binding site is on the external surface and is only accessible in the open conformation of RFC. Initial DNA binding at this site thus provides access to the primary DNA binding site in the central chamber. Furthermore, we identify that this site can partially unwind DNA to create an extended single-stranded gap for DNA binding in RFC’s central chamber and subsequent ATPase activation. Finally, we show that deletion of the BRCT domain, a major component of the external DNA binding site, results in defective yeast growth in the presence of DNA damage where nicked or gapped DNA intermediates occur. We propose that RFC’s external DNA binding site acts to enhance DNA binding and clamp loading, particularly at DNA architectures typically found in DNA repair.

Acetylation of H3K56 orchestrates UV-responsive chromatin events that generate DNA accessibility during Nucleotide Excision Repair

Histone modifications have long been related to DNA damage response. Nucleotide excision repair pathway that removes helix-distorting lesions necessitates DNA accessibility through chromatin modifications. Previous studies have linked H3 tail residue acetylation to UV-induced NER. Here we present evidences that acetylation of H3K56 is crucial for early phases of NER. Using H3K56 mutants K56Q and K56R, which mimic acetylated and unacetylated lysines respectively, we show that recruitment of the repair factor Rad16, a Swi/Snf family member is dependent on H3K56 acetylation. With constitutive H3K56 acetylation, Rad16 recruitment became UV-independent. Furthermore, H3K56 acetylation promoted UV-induced hyperacetylation of H3K9 and H3K14. Importantly, constitutive H3K56 acetylation prominently increased chromatin accessibility. During NER, lack of H3K56 acetylation that effectively aborted H3 tail residue acetylation and Rad16 recruitment, thus failed to impart essential chromatin modulations. The NER-responsive oscillation of chromatin structure observed in wild type, was distinctly eliminated in absence of H3K56 acetylation. In vitro assay with wild type and H3K56 mutant cell extracts further indicated that absence of H3K56 acetylation negatively affected DNA relaxation during NER. Overall, H3K56 acetylation regulates Rad16 redistribution and UV-induced H3 tail residue hyperacetylation, and the resultant modification code promotes chromatin accessibility and recruitment of subsequent repair factors during NER.

Tissue-specific DNA damage response in Mouse Whole-body irradiation

Background

Genomic instability is a hallmark of various cancers, and DNA repair is an essential process for maintaining genomic integrity. Mammalian cells have developed various DNA repair mechanisms in response to DNA damage. Compared to the cellular response to DNA damage, the in vivo DNA damage response (DDR) of specific tissues has not been studied extensively.

Objective

In this study, mice were exposed to whole-body gamma (γ)-irradiation to evaluate the specific DDR of various tissues. We treated male C57BL6/J mice with γ-irradiation at different doses, and the DDR protein levels in different tissues were analyzed.

Results

The level of gamma-H2A histone family member X (γH2AX) increased in most organs after exposure to γ-irradiation. In particular, the liver, lung, and kidney tissues showed higher γH2AX induction upon DNA damage, compared to that in the brain, muscle, and testis tissues. RAD51 was highly expressed in the testis, irrespective of irradiation. The levels of proliferating cell nuclear antigen (PCNA) and ubiquitinated PCNA increased in lung tissues upon irradiation, suggesting that the post-replication repair may mainly operate in the lungs in response to γ-irradiation.

Conclusion

These results suggest that each tissue has a preferable repair mechanism in response to γ-irradiation. Therefore, the understanding and application of tissue-specific DNA damage responses could improve the clinical approach of radiotherapy for treating specific cancers.

Developmental series of gene expression clarifies maternal mRNA provisioning and maternal-to-zygotic transition in a reef-building coral

BACKGROUND

Maternal mRNA provisioning of oocytes regulates early embryogenesis. Maternal transcripts are degraded as zygotic genome activation (ZGA) intensifies, a phenomenon known as the maternal-to-zygotic transition (MZT). Here, we examine gene expression over nine developmental stages in the Pacific rice coral, Montipora capitata, from eggs and embryos at 1, 4, 9, 14, 22, and 36 h-post-fertilization (hpf), as well as swimming larvae (9d), and adult colonies.

RESULTS

Weighted Gene Coexpression Network Analysis revealed four expression peaks, identifying the maternal complement, two waves of the MZT, and adult expression. Gene ontology enrichment revealed maternal mRNAs are dominated by cell division, methylation, biosynthesis, metabolism, and protein/RNA processing and transport functions. The first MZT wave occurs from ~4-14 hpf and is enriched in terms related to biosynthesis, methylation, cell division, and transcription. In contrast, functional enrichment in the second MZT wave, or ZGA, from 22 hpf-9dpf, includes ion/peptide transport and cell signaling. Finally, adult expression is enriched for functions related to signaling, metabolism, and ion/peptide transport. Our proposed MZT timing is further supported by expression of enzymes involved in zygotic transcriptional repression (Kaiso) and activation (Sox2), which peak at 14 hpf and 22 hpf, respectively. Further, DNA methylation writing (DNMT3a) and removing (TET1) enzymes peak and remain stable past ~4 hpf, suggesting that methylome programming occurs before 4 hpf.

CONCLUSIONS

Our high-resolution insight into the coral maternal mRNA and MZT provides essential baseline information to understand parental carryover effects and the sensitivity of developmental success under increasing environmental stress.

TEMPO/TCC as a Chemo Selective Alternative for the Oxidation of Hyaluronic Acid

Hyaluronic acid (HA)-based hydrogels are very commonly applied as cell carriers for different approaches in regenerative medicine. HA itself is a well-studied biomolecule that originates from the physiological extracellular matrix (ECM) of mammalians and, due to its acidic polysaccharide structure, offers many different possibilities for suitable chemical modifications which are necessary to control, for example, network formation. Most of these chemical modifications are performed using the free acid function of the polymer and, additionally, lead to an undesirable breakdown of the biopolymer’s backbone. An alternative modification of the vicinal diol of the glucuronic acid is oxidation with sodium periodate to generate dialdehydes via a ring opening mechanism that can subsequently be further modified or crosslinked via Schiff base chemistry. Since this oxidation causes a structural destruction of the polysaccharide backbone, it was our intention to study a novel synthesis protocol frequently applied to selectively oxidize the C6 hydroxyl group of saccharides. On the basis of this TEMPO/TCC oxidation, we studied an alternative hydrogel platform based on oxidized HA crosslinked using adipic acid dihydrazide as the crosslinker.

Extenuating role of lycopene against 254-nm UV-C radiation-mediated damages in Allium cepa L. roots

UV-C exposure has become a crucial risk for living organisms due to its widespread use in sterilization. In this study, the mitigating potential of lycopene was investigated against UV-C-mediated toxicity in Allium cepa L. roots. Allium bulbs were separated into six groups which treated with tap water, 215 mg/L lycopene, 430 mg/L lycopene, 254-nm UV radiation, 215 mg/L lycopene + 254-nm UV radiation, and 430 mg/L lycopene + 254-nm UV radiation. Germination percentage, root length, weight gain, mitotic index, micronucleus frequency, and other chromosomal aberrations as well as meristematic cell damages were investigated in all groups. Malondialdehyde level and the activities of superoxide dismutase and catalase enzymes were also analyzed to understand the severity of oxidative stress. UV-C radiation was revealed to negatively affect all parameters investigated, while the mitigating activities of lycopene against UV-C-mediated toxicity were dose-dependent. Therefore, the study evidently demonstrated the promising potential of lycopene in the protection against the detrimental effects of UV-C exposure in A. cepa.

Hymenobacter puniceus sp. nov., radiation resistant bacteria isolated from soil in South Korea

Two novel Gram-negative bacterial strains BT190^T and BT191 were isolated from soil collected in Uijeongbu city (37°44'55″N, 127°02'20″E), Korea. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strains BT190^T and BT191 belong to a distinct lineage within the genus Hymenobacter (family Hymenobacteraceae, order Cytophagales, class Cytophagia). The level of 16S rRNA gene sequence similarity between the strains BT190^T and BT190 was 99.5%. The strains BT190^T and BT191 were closely related to Hymenobacter swuensis DY53^T (97.0% 16S rRNA gene similarity), Hymenobacter metallilatus 9PBR-2 ^T (96.8%), Hymenobacter tibetensis XTM003^T (96.8%) and Hymenobacter yonginensis HMD1010^T (96.6%). The genome size of strain BT190^T was 4,859,864 bp. The DNA G+C content of strain BT190^T was 55.3 mol%. Bacterial growth was observed at 4-30 °C (optimum 25 °C) and pH 6.0-9.0 (optimum, pH 6.0-7.0) on R2A agar. Colonies of strains BT190^T and BT191 were raised, smooth, circular and red-pink colored. The sole respiratory quinone of strain BT190^T was MK-7 and the predominant cellular fatty acids were iso-C_15:0, C_16:1 ω5c, summed feature 3 (C_16:1 ω6c / C_16:1 ω7c) and summed feature 4 (iso-C_17:1 I / anteiso-C_17:1 B). The major polar lipids of strain BT190^T were aminophospholipid (APL) and phosphatidylethanolamine (PE). Based on the chemotaxonomic, biochemical, and phylogenetic analysis, strains BT190^T and BT191 can be suggested as a novel bacterial species within the genus Hymenobacter, for which the name Hymenobacter puniceus sp. nov is proposed. The type strain of Hymenobacter puniceus is BT190^T (= KCTC 72342 ^T = NBRC 114860 ^T).

Hymenobacter guriensis sp. nov., and Hymenobacter duratus sp. nov., Radiation-Resistant Species Isolated from Soil in South Korea

Two novel Gram-stain-negative, non-motile, aerobic, rod-shaped, circular, convex, red-colored and UV-tolerant strains BT594^T and BT646^T were isolated from soil collected in Guri city (37° 36' 0″ N, 127° 9' 0″ E) and Gwangju city (37° 22' 0″ N, 127° 17' 0″ E), respectively, South Korea. 16S rDNA sequence analysis indicated that strains BT594^T and BT646^T belong to a distinct lineage within the genus Hymenobacter (family Hymenobacteraceae, order Cytophagales, class Cytophagia, phylum Bacteroidetes, kingdom Bacteria). The 16S rDNA gene sequence similarity between the two strains BT594^T and BT646^T was 96.2%. The strain BT594^T was closely related to Hymenobacter psychrotolerans Tibet-IIU11^T (97.0% 16S rDNA gene similarity) and Hymenobacter tibetensis XTM003^T (96.3%). The strain BT646^T was closely related to Hymenobacter psychrotolerans Tibet-IIU11^T (98.6%), Hymenobacter kanuolensis T-3 ^T (96.8%) and Hymenobacter perfusus LMG 26000 ^T (96.7%). The two strains were found to have the same quinone system, with MK-7 as the major respiratory quinone. The major polar lipids of strains BT594^T and BT646^T were phosphatidylethanolamine (PE) and aminophospholipids (APL). The major cellular fatty acids of strain BT594^T were anteiso-C_15:0 (17.9%), iso-C_15:0 (16.1%) and summed feature 3 (C_16:1 ω6c / C_16:1 ω7c) (10.0%). The major cellular fatty acids of strain BT646^T were summed feature 3 (C_16:1 ω6c / C_16:1 ω7c) (18.3%), C_16:0 (17.2%) and summed feature 4 (iso-C_17:1 I / anteiso-C_17:1 B) (14.5%). Based on the polyphasic analysis, strains BT594^T and BT646^T can be suggested as two novel bacterial species within the genus Hymenobacter and the proposed names are Hymenobacter guriensis and Hymenobacter duratus, respectively. The type strain of Hymenobacter guriensis is BT594^T (= KCTC 21863 ^T = NBRC 114853 ^T) and the type strain of Hymenobacter duratus is BT646^T (= KCTC 21915 ^T = NBRC 114854 ^T).

Methylobacterium radiodurans sp. nov., a novel radiation-resistant Methylobacterium

A Gram-negative, aerobic, flagellated, rod-shaped, and pink-pigmented bacterium, strain 17Sr1-43 ^T, was isolated from a soil sample collected in Nowongu, Seoul, Korea. The isolate could grow at 18-37 °C (optimum, 28-30 °C), pH 6.0-8.0 (optimum, pH 7.0) and in the presence of 0-1.0% (w/v) NaCl (optimum, 0%) with aeration. The major cellular fatty acids were summed feature 8 (C_18:1 ω7c and/or C_18:1 ω6c) and summed feature 2 (iso-C_16:1 I and/or C_14:0 3-OH). The predominant respiratory quinone was Q-10 and the major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, phospholipid, and diphosphatidylglycerol. The G + C content of genomic DNA was 69.1 mol%. Strain 17Sr1-43 ^T was closely related to Methylobacterium gregans KACC 14808 ^T (98.4% 16S rRNA gene sequence similarity), Methylobacterium hispanicum KACC 11432 ^T (97.9%), and Methylobacterium phyllosphaerae CBMB27^T (96.1%). The complete genome of strain 17Sr1-43 ^T contains essential genes related to DNA repair processes including bacterial RecBCD dependent pathway and UmuCD system. Based on the phenotypic, genotypic, and chemotaxonomic characteristics, strain 17Sr1-43 ^T represents a novel species in the genus Methylobacterium, for which the name Methylobacterium radiodurans sp. nov. is proposed. The type strain is strain 17Sr1-43 ^T (= KCTC 52906 ^T = NBRC 112875 ^T).

Terahertz pulse-altered gene networks in human induced pluripotent stem cells

Terahertz (THz) irradiation has been exploited in biomedical applications involving non-invasive manipulation of living cells. We developed an apparatus for studying the effects of THz pulse irradiation on living human induced pluripotent stem cells. The THz pulse of the maximum electric field reached 0.5 MV/cm and was applied for one hour with 1 kHz repetition to the entire cell-culture area, a diameter of 1 mm. RNA sequencing of global gene-expression revealed that many THz-regulated genes were driven by zinc-finger transcription factors. Combined with a consideration of the interactions of metal ions and a THz electric field, these results imply that the local intracellular concentration of metal ions, such as Zn²⁺, was changed by the effective electrical force of our THz pulse.

Hymenobacter radiodurans sp. nov., isolated from soil in the Republic of Korea

A bacterial strain, designated 17J36-26^T, was isolated from the UV-irradiated soil from Jeju Island, South Korea. Cells are Gram negative, strictly aerobic, non-motile, non-spore forming, rod shaped, and catalase and oxidase positive. The major fatty acids of strain 17J36-26^T were summed feature 4 (17:1 iso I/17:1 anteiso B), summed feature 3 (16:1 ω6c/16:1 ω7c), C_16:1 ω5c and iso-C_15:0. The polar lipid profile contained phosphatidylethanolamine, unidentified aminophospholipid, phospholipids and four unidentified lipids. The G+C content of the strain 17J36-26^T was 62.6 mol%. The 16S rRNA gene sequence analysis showed that strain 17J36-26^T was phylogenetically related to Hymenobacter qilianensis DK6-37^T and Hymenobacter roseosalivarius AA718^T (97.5% and 96.8% sequence similarity, respectively). Strain 17J36-26^T showed resistance to UV radiation. Both average nucleotide identity (ANI) and in silico DNA-DNA hybridization (isDDH) values between strains 17J36-26^T and type strains of Hymenobacter species were lower than the cut-off (≥ 95-96% for ANI and ≥ 70% for isDDH) to define a bacterial new species. The polyphasic approach using genotypic, phenotypic and chemotaxonomic data showed that strain 17J36-26^T could be distinguished from its phylogenetically related species, and thus, the strain representative of a novel species within the genus Hymenobacter, for which the name Hymenobacter radiodurans sp. nov. (type strain 17J36-26^T = KCTC 62269^T = JCM 33185^T) is proposed.

Rufibacter radiotolerans sp. nov., a novel gamma-radiation-resistant bacterium isolated from rice field

A red-pigmented isolate, designated DG31D^T, was isolated from the soil of a rice field in South Korea. Cells were strictly aerobic, short rod-shaped, Gram-negative, oxidase-positive, and catalase-positive. The major polar lipid was phosphatidylethanolamine (PE), and the predominant respiratory quinone was MK-7. DG31D^T showed high resistance to both the UV and gamma radiations. Based on the 16S rRNA gene sequence, strain DG31D^T was related to Rufibacter immobilis MCC P1^T (97.1%) and Rufibacter tibetensis 1351^T (96.5%). The average nucleotide identity (ANI) and in silico DNA-DNA hybridization (isDDH) values between the strain DG31D^T and the related Rufibacter sp. were between 74.1-77.6% and 19.9-21.9%, respectively. Strain DG31D^T grew between 15 and 30 °C (optimum, 25 °C), at pH 6.0-8.0 (optimum, pH 7.0) and tolerated up to 1.0% NaCl (w/v). The major cellular fatty acids of the novel strain were summed feature 3 (C_16:1 ω7c/C_16:1 ω6c) and C_16:1 ω5c. Flexirubin-type pigments were absent. On the basis of the phenotypic, phylogenetic, and chemotaxonomic data, strain DG31D^T represents a novel species of the genus Rufibacter, for which the name Rufibacter radiotolerans sp. nov. is proposed. The type strain is DG31D^T (= JCM 19446^T = KCTC 32454^T).

Regiochemical memory in the adiabatic photolysis of thymine-derived oxetanes. A combined ultrafast spectroscopic and CASSCF/CASPT2 computational study

The photoinduced cycloreversion of oxetanes has been thoroughly investigated in connection with the photorepair of the well-known DNA (6-4) photoproducts. In the present work, the direct photolysis of the two regioisomers arising from the irradiation of benzophenone (BP) and 1,3-dimethylthymine (DMT), namely the head-to-head (HH-1) and head-to-tail (HT-1) oxetane adducts, has been investigated by combining ultrafast spectroscopy and theoretical multiconfigurational quantum chemistry analysis. Both the experimental and computational results agree with the involvement of an excited triplet exciplex 3[BPDMT]* for the photoinduced oxetane cleavage to generate 3BP* and DMT through an adiabatic photochemical reaction. The experimental signature of 3[BPDMT]* is the appearance of an absorption band at ca. 400 nm, detected by femtosecond transient absorption spectroscopy. Its formation is markedly regioselective, as it is more efficient and proceeds faster for HH-1 (∼2.8 ps) than for HT-1 (∼6.3 ps). This is in line with the theoretical analysis, which predicts an energy barrier to reach the triplet exciplex for HT-1, in contrast with a less hindered profile for HH-1. Finally, the more favorable adiabatic cycloreversion of HH-1 compared to that of HT-1 is explained by its lower probability to reach the intersystem crossing with the ground state, which would induce a radiationless deactivation process leading either to a starting adduct or to a dissociated BP and DMT.

Hymenobacter jejuensis sp. nov., a UV radiation-tolerant bacterium isolated from Jeju Island

A novel Gram-stain negative, aerobic, rod-shaped, non-motile and pink-coloured bacterium, designated strain 17J68-5^T, was isolated from soil in Jeju Island, Korea. The strain was found to grow at 18-37 °C (optimum 25 °C) in R2A medium at pH (6.0 to 7.5; optimum 6.5) in the presence of 0% (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain 17J68-5^T forms a distinct lineage within the family Hymenobacteraceae and is closely related to Hymenobacter daecheongensis DSM 21074^T (94.9% 16S rRNA gene sequence similarity), Hymenobacter rutilus K2-33028^T (94.6%) and Hymenobacter tibetensis XTM003^T (94.3%). The draft genome sequence of strain 17J68-5^Tis 5.1 Mb size. The calculated average nucleotide identity and the digital DNA-DNA hybridization between strain 17J68-5^T and closely related type strains were 81.3 to 84.1  % and 25.5 to 28.1%. The major cellular fatty acids (≥ 10%) of the strain 17J68-5^T were identified as summed feature 3 (C_16:1ω6c/C_16:1ω7c; 21.2%), iso-C_15:0 (19.1%), summed feature 4 (C_17:1 iso I/C_17:1 anteiso B; 17.9%) and C_16:1ω5c (13.1%). The predominant respiratory quinones were found to be menaquinone 7 and 6 (MK-7 and MK-6). The major polar lipid was found to be phosphatidylethanolamine. The genomic DNA G + C content based on the whole genome sequence is 59.6 mol %. The phenotypic, chemotaxonomic and genotypic properties clearly indicated that isolate 17J68-5^T represents a novel species within the genus Hymenobacter, for which the name Hymenobacter jejuensis sp. nov. is proposed. The type strain of Hymenobacter jejuensis is 17J68-5^T (= KCTC 62224^T = JCM 33182^T).

Somatic and Germline Mutation Periodicity Follow the Orientation of the DNA Minor Groove around Nucleosomes

Mutation rates along the genome are highly variable and influenced by several chromatin features. Here, we addressed how nucleosomes, the most pervasive chromatin structure in eukaryotes, affect the generation of mutations. We discovered that within nucleosomes, the somatic mutation rate across several tumor cohorts exhibits a strong 10 base pair (bp) periodicity. This periodic pattern tracks the alternation of the DNA minor groove facing toward and away from the histones. The strength and phase of the mutation rate periodicity are determined by the mutational processes active in tumors. We uncovered similar periodic patterns in the genetic variation among human and Arabidopsis populations, also detectable in their divergence from close species, indicating that the same principles underlie germline and somatic mutation rates. We propose that differential DNA damage and repair processes dependent on the minor groove orientation in nucleosome-bound DNA contribute to the 10-bp periodicity in AT/CG content in eukaryotic genomes.

Overexpressed vascular endothelial growth factor in adipose derived stem cells attenuates fibroblasts and skin injuries by ultraviolet radiation

Adipose-derived stem cells (ADSCs) and vascular endothelial growth factor (VEGF) contribute to the healing of wound. The purpose of the present study was to investigate the role of VEGF produced by ADSCs in the protection of fibroblasts and skin of mice from ultraviolet (UV) radiation. ADSCs and fibroblasts were extracted from adipose and skin on the abdomen of mice by enzyme digestion methods. ADSCs surface markers were detected using flow cytometry, and immunofluorescence was used to identify fibroblasts. The expression of VEGF in modified ADSCs with lentivirus was determined. Fibroblasts were injured by UV radiation and co-cultured with ADSCs carrying overexpressed VEGF or normal VEGF. Cell cycle was assessed by flow cytometry. Mice were treated with UV radiation dorsally and injected with ADSCs containing overexpressed VEGF or normal VEGF. mRNA and protein levels of cell senescence-related genes were measured by qPCR and western blot. It was found that ADSCs with overexpressed VEGF not only promoted the effect of ADSCs on down-regulating senescence-associated (SA)-β-Gal, p21 and matrix metalloproteinase (MMP)-1, the healing of wound injured by UV radiation and up-regulating collagen I expression in fibroblasts and wound, but also on inhibiting cell cycle arrest in fibroblasts injured by UV radiation and preventing the skin from photoaging caused by UV radiation. VEGF expression in ADSCs played a key role in protecting skin fibroblasts from ageing, which further allowed the skin to resist photoaging, thereby promoting the recovery of wound injured by UV radiation.

Paenibacillus albus sp. nov., a UV radiation-resistant bacterium isolated from soil in Korea

A novel Gram-stain-positive, motile, white color and endospore-forming bacterium, designated 18JY67-1^T, was isolated from soil in Jeju Island, Korea. The strain grow at 15-42 °C (optimum 30 °C) in R2A medium at pH (6.0-9.5) (optimum 7.5). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain 18JY67-1^T formed a distinct lineage within the family Paenibacillaceae (order Bacillales, class Bacilli), and was closely related to Paenibacillus rhizoryzae (KP675984; 96.9% 16S rRNA gene sequence similarity). The major cellular fatty acids of the strain 18JY67-1^T were C_16:0 and anteiso-C_15:0. The predominant respiratory quinones were MK-7. The major polar lipid was identified as diphosphatidylglycerol. On the basis of phenotypic, chemotaxonomic and genotypic properties clearly indicated that isolate 18JY67-1^T represents a novel species within the genus Paenibacillus, for which the name Paenibacillus flavus sp. nov. is proposed. The type strain of Paenibacillus flavus is 18JY67-1^T (= KCTC 33959^T = JCM 33184^T).

Antioxidant and cytoprotective effects of Stachys riederi var. japonica ethanol extract on UVA‑irradiated human dermal fibroblasts

Stachys riederi is one of the largest genera in the flowering plant family Lamiaceae. The aqueous extract of Stachys riederi var. japonica is known for its anti‑allergic effect. In the present study, the antioxidant and cytoprotective effects of Stachys riederi var. japonica ethanol extract (SREE) on ultraviolet A (UVA)‑irradiated human dermal fibroblasts (HDFs) were evaluated. At 100 µg/ml, SREE significantly inhibited production of reactive oxygen species (ROS) in UVA‑irradiated HDFs. SREE at 100 µg/ml additionally markedly interfered with the loss of mitochondrial membrane potential (ΔΨm) in these cells. In addition, SREE at 100 µg/ml attenuated UVA‑induced DNA fragmentation and caspase‑3 activation in HDFs. SREE at 100 µg/ml additionally increased mRNA and protein expressions of Bcl‑2 and decreased those of Bax and cytochrome c in UVA‑irradiated HDFs. In summary, to the best of our knowledge, these results demonstrate for the first time that SREE exhibited antioxidant and cytoprotective effects on UVA‑irradiated HDFs, which may be mediated through suppression of ROS generation, inhibition of the loss of ΔΨm and inhibition of apoptosis.

Translation regulation in skin cancer from a tRNA point of view

Protein synthesis is a central and dynamic process, frequently deregulated in cancer through aberrant activation or expression of translation initiation factors and tRNAs. The discovery of tRNA-derived fragments, a new class of abundant and, in some cases stress-induced, small Noncoding RNAs has perplexed the epigenomics landscape and highlights the emerging regulatory role of tRNAs in translation and beyond. Skin is the biggest organ in human body, which maintains homeostasis of its multilayers through regulatory networks that induce translational reprogramming, and modulate tRNA transcription, modification and fragmentation, in response to various stress signals, like UV irradiation. In this review, we summarize recent knowledge on the role of translation regulation and tRNA biology in the alarming prevalence of skin cancer.

Otological surgery in paediatric photosensitive patients

There are a wide range of genetic and auto-immune conditions where UV light exposure poses a threat of UV irradiation to the external auditory canal, tympanic membrane and surrounding skin. Preoperative Ultraviolet Light (UV) measurements were taken in the operating theatre with standard operating microscope and an approved UV light meter prior to surgery on a patient with xeroderma pigmentosa. UV light meter readings of UV index 75 were taken at an operating distance of 290mm. Proceeding with otological surgery with a high UV index would result in a significant UV radiation burn. Utilising a Dermagard and a specific UV filter applied to the microscope resulted in acceptable UV light readings. We highlight the potential morbidity of otological surgery in paediatric photosensitive conditions. We also recommend a management plan to avoid damage by UV radiation in photosensitive patients.

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.

Deinococcus irradiatisoli sp. nov., isolated from gamma ray-irradiated soil

Strain 17bor-2^T, a gamma-resistant, pink-to-red-coloured, aerobic, catalase-positive, oxidase-negative and Gram-stain-negative bacterium, was isolated from gamma ray-irradiated soil. The isolate grew aerobically at 18-37 °C (optimum, 28-30 °C), pH 6.0-8.0 (pH 6.5-7.5) and in the presence of 0-1 % (w/v) NaCl (0 % NaCl). Phylogenetic analysis based on its 16S rRNA gene sequence indicated that strain 17bor-2^T belonged to the genus Deinococcus with a highest sequence similarity of 96.4 % to Deinococcus alpinitundrae ME-04-04-52^T. The major fatty acids of the strain were summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), C16 : 0 and cyclo C17 : 0. The only respiratory quinone was MK-8. The major polar lipids of the strain were phosphoglycolipid, aminophospholipid and an unknown glycolipid. The DNA G+C content of strain 17bor-2^T was 62.8 mol%. On the basis of its phenotypic, genotypic and chemotaxonomic characteristics, strain 17bor-2^T should be classified as a novel species in the genus Deinococcus, for which the name Deinococcusirradiatisoli sp. nov. is proposed. The type strain is 17bor-2^T (=KCTC 33907^T=NBRC 113037^T).

Roseomonas radiodurans sp. nov., a gamma-radiation-resistant bacterium isolated from gamma ray-irradiated soil

A bacterial strain, designated 17Sr1-1^T, was isolated from gamma ray-irradiated soil. Cells of this strain were Gram-stain-negative, strictly aerobic, motile and non-spore-forming rods. Growth occurred at 18-42 ˚C and pH 6.0-8.0, but no growth occurred at 2 % NaCl concentration. The major fatty acids of strain 17Sr1-1^T were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c), iso-C17 : 1ω5c and C16 : 0. The polar lipid profile contained diphosphatidylglycerol, glycolipid, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and four unidentified lipids. The G+C content of the genomic DNA of 17Sr1-1^T was 71.9 mol%. The 16S rRNA gene sequence analysis showed that strain 17Sr1-1^T was phylogenetically related to Roseomonas pecuniae N75^T and Roseomonas rosea 173-96^T (96.6 and 96.3 % sequence similarity, respectively). The genotypic and phenotypic data showed that strain 17Sr1-1^T could be distinguished from its phylogenetically related species, and that this strain represented a novel species within the genus Roseomonas, for which the name Roseomonas radiodurans sp. nov. (type strain 17Sr1-1^T=KCTC 52899^T=NBRC 112872^T) is proposed as the first reported gamma ray-resistant Roseomonas species.

Genomic Approach to Understand the Association of DNA Repair with Longevity and Healthy Aging Using Genomic Databases of Oldest-Old Population

Aged population is increasing worldwide due to the aging process that is inevitable. Accordingly, longevity and healthy aging have been spotlighted to promote social contribution of aged population. Many studies in the past few decades have reported the process of aging and longevity, emphasizing the importance of maintaining genomic stability in exceptionally long-lived population. Underlying reason of longevity remains unclear due to its complexity involving multiple factors. With advances in sequencing technology and human genome-associated approaches, studies based on population-based genomic studies are increasing. In this review, we summarize recent longevity and healthy aging studies of human population focusing on DNA repair as a major factor in maintaining genome integrity. To keep pace with recent growth in genomic research, aging- and longevity-associated genomic databases are also briefly introduced. To suggest novel approaches to investigate longevity-associated genetic variants related to DNA repair using genomic databases, gene set analysis was conducted, focusing on DNA repair- and longevity-associated genes. Their biological networks were additionally analyzed to grasp major factors containing genetic variants of human longevity and healthy aging in DNA repair mechanisms. In summary, this review emphasizes DNA repair activity in human longevity and suggests approach to conduct DNA repair-associated genomic study on human healthy aging.

Visible Light-Induced Radical Mediated DNA Damage

Light-responsive compounds have been used to manipulate biological systems with spatial and temporal control of the event of interest. Illumination of alkylcobalamins with green light (>500 nm) produces carbon-centered radicals, which have been demonstrated to effectively cause DNA damage. Molecules that cause DNA and RNA strand scission are useful for studying polynucleotide structure and the binding of small molecules and proteins to polynucleotides. Most molecules that cause DNA damage in a light-dependent manner require high energy, short wavelength ultraviolet light, which is readily absorbed by nucleotide bases causing damage to the polynucleotides. Therefore, using alkylcobalamins is advantageous for causing strand scission of polynucleotides, because they are activated by light wavelengths that are not absorbed by nucleotide bases. Green-light illumination of methylcobalamin effectively causes DNA strand scission based on gel mobility assays. This cleavage is due to the generation of carbon-centered radicals based on the results of a radical trapping study. In addition, synthesis of an alkylcobalamin with a DNA binding moiety, spermine, improves DNA cleavage efficacy by an order of magnitude in comparison with methylcobalamin.

Kurthia ruminicola sp. nov., isolated from the rumen contents of a Holstein cow

Gram-staining-positive, motile, rod-shaped bacteria, designated as H31022^T and H31024 was isolated from rumen contents of a Holstein cow. Optimum growth occurred at 25°C and pH 7.0 on R2A agar medium. Oxidase and catalase activities are positive. The 16S rRNA gene sequence (1,452 bp) of the new isolates revealed they belong to the genus Kurthia of the phylum Firmicutes. Highest gene sequence similarities were assessed to be with Kurthia massiliensis JC30^T (98.4%), Kurthia senegalensis JC8E^T (97.5%), and Kurthia populi 10y-14^T (97.4%). Kurthia sibirica DSM 4747^T (97.3%), Kurthia zopfii NBRC 101529^T (97.0%), and Kurthia gibsonii NCIMB 9758^T (96.7%). DNA G + C content of strains H31022^T and H31024 were 34.4% and 39.7%. Strains H31022^T and H31024 has the following chemotaxonomic characteristics; the major fatty acids are iso-C_15:0, iso-C_14:0 and anteiso-C₁₅; polar lipid profile contained diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), unknown aminophospholipids (APL), unknown glycolipids (GL), unknown phospholipids (PL), and unknown polar lipids (L); the major quinone is MK-7. Based on polyphasic taxonomic analysis, strains H31022^T (= KCTC 33923^T = JCM 19640^T) and H31024 (= KCTC 33924^T = JCM 19641^T) identified a novel species in the genus Kurthia for which the name Kurthia ruminicola sp. nov. is proposed.

Transcriptome analysis for UVB-induced phototoxicity in mouse retina

Throughout life, the human eye is continuously exposed to sunlight and artificial lighting. Ambient light exposure can lead to visual impairment and transient or permanent blindness. To mimic benign light stress conditions, Mus musculus eyes were exposed to low-energy UVB radiation, ensuring no severe morphological changes in the retinal structure post-exposure. We performed RNA-seq analysis to reveal the early transcriptional changes and key molecular pathways involved before the activation of the canonical cell death pathway. RNA-seq analysis identified 537 genes that were differentially modulated, out of which 126 were clearly up regulated (>2-fold, P < .01) and 51 were significantly down regulated (<2-fold, P < .01) in response to UVB irradiation in the mouse retina. Gene ontology analysis revealed that UVB exposure affected pathways for cellular stress and signaling (eg, Creb3, Ddrgk1, Grin1, Map7, Uqcc2, Uqcrb), regulation of chromatin and gene expression (eg, Chd5, Jarid2, Kat6a, Smarcc2, Sumo1, Zfp84), transcription factors (eg, Asxl2, Atf7, Per1, Phox2a, Rxra), RNA processing, and neuronal genes (eg, B4gal2, Drd1, Grm5, Rnf40, Rnps1, Usp39, Wbp4). The differentially expressed genes from the RNA-seq analysis were validated by quantitative PCR. Both analyses yielded similar gene expression patterns. The genes and pathways identified here improve the understanding of early transcriptional responses to UVB irradiation. They may also help in elucidating the genes responsible for the inherent susceptibility of humans to UVB-induced retinal diseases.