Ultraviolet Radiation Absorbance by Coral Reef Fish Mucus: photo-protection and Visual Communication

Tropical reef fishes are exposed to high levels of damaging ultraviolet radiation. Here we report the widespread distribution of both UVA- and UVB-absorbing compounds in the epithelial mucus of these fishes. Mucus from 137 reef fish species was examined by spectrophotometry and 90% were found to have strong absorbance peaks between 290 and 400nm. Most fish species (78%) had more than one peak, that suggests a broad-band ultraviolet screening function for their mucus. Thalassoma duperrey, a tropical wrasse, was able to alter the absorbance of its epithelial mucus in response to both naturally and experimentally manipulated UV regimes. Visual modeling suggests that a fish with UV vision, such as Dascyllus albisella, could detect the changes in mucus spectra of T. duperrey that occurred in these experiments.     

Melanin and Cellular Reactions to Ultraviolet Radiation

THERE has been much discussion about the importance of melanin in protecting skin against the damaging effects of sunlight and/or ultraviolet radiation^1–4; absorption and scattering by melanin protect intracellular organelles and cells in vitro^5,6. But we now believe that a number of the so-called “sunburn cells”, the dyskeratotic cells present in epidermis 12–48 h after irradiation^7–9, contain granules of melanin. Furthermore, they contain more granules than neighbouring, apparently undamaged cells. Thus paradoxically, cells containing what should be a protective compound are killed, while those containing less or none are apparently undamaged.     

Ultraviolet Radiation Alters Maize Phyllosphere Bacterial Diversity

Epiphytic bacteria are subjected to very stressful environments, including UV radiation. Bacterial assemblages on Zea mays (maize) leaves exposure were examined with and without UV-B radiation. Culture-independent molecular techniques were utilized for bacterial identification, diversity analysis and selection of putative UV exposure marker sequences. Few sequences corresponded to previously characterized phyllosphere bacteria. There was a strong tendency toward increased 16S rDNA sequence diversity in UV samples. Overall community structure was assessed using denaturing gel gradient electrophoresis; significant alterations in community structure were found in comparisons of phyllosphere bacterial samples from control and solar UV-B exposed plants.     

Susceptibility of Legionella pneumophila to Ultraviolet Radiation

Distilled water suspensions of Legionella pneumophila were found to be sensitive to low doses of germicidal ultraviolet radiation.     

紫外线辐射对蓝藻细胞活性的影响

紫外线辐射 2种蓝藻Anabaena 6 3l和Anabaenaazollae不同时间 ,用UV30 0 0分光光度计测定活体连续吸收光谱 ,并测定细胞存活率。结果发现紫外线辐射对这 2种蓝藻的光合色素有不同程度的破坏作用 ;紫外线辐射 2min左右就可以杀死全部的A .6 3l和A .azollae细胞。实验还证实了小剂量刺激效应的存在。     

紫外辐射的细胞生物学效应及其机制

地球表面的生物体会受到来自阳光紫外辐射的照射。两极臭氧层空洞的形成使地球表面的紫外辐射水平,特别是UVB的水平增加,进而对生物体的危害日益加重。因此,深入研究紫外辐射生物学效应的信号转导机制并阐明其损伤机制和生物体的反应机制等具有重要意义,也可为紫外辐射损伤防护的研究提供新思路。本文综述了本领域近年来的相关研究,从紫外辐射所致生物学效应的信号转导机制(包括对DNA的直接损伤作用、细胞膜激酶和非激酶受体通路、细胞质通路以及microRNA)等方面对紫外辐射的损伤机制进行了比较系统的阐述和总结。     

Integrated Human and Ecological Risk Assessment: A Case Study of Ultraviolet Radiation Effects on Amphibians,Coral, Humans,and Oceanic Primary Productivity

Ultraviolet radiation (UVR) is a naturally occurring stressor to most forms of life. The sole relevant source of this stressor is the sun. The Earth's stratospheric ozone layer reduces the amount of UVR that reaches the Earth's surface. The potential for continued depletion of this ozone layer and environmental changes that increase the penetrance of aquatic habitat, both due to human activities, and the subsequent increase in UVR are global environmental concerns for both humans and ecosystems. An integrated risk assessment provides efficiency in data gathering, analysis and reporting by enabling risk assessors to use the combined knowledge from many disciplines to evaluate overall risk. This report describes the steps and example information that could be used for an integrated risk assessment but is not an actual risk assessment with all its associated calculations and conclusions. It is intended to illustrate the advantages of the integrated risk assessment approach for evaluating adverse effects of a nonchemical stressor.     

Ultraviolet Radiation and the Photobiology of Earth's Early Oceans

During the Archean era (3.9–2.5 Ga ago) the earth was dominatedby an oceanic lithosphere. Thus, understanding how life aroseand persisted in the Archean oceans constitutes a majorchallenge in understanding early life on earth. Using aradiative transfer model of the late Archean oceans, thephotobiological environment of the photic zone and the surfacemicrolayer is explored at the time before the formation of a significant ozonecolumn. DNA damage rates might have been approximately threeorders of magnitude higher in the surface layer of the Archeanoceans than on the present-day oceans, but at 30 m depth,damage may have been similar to the surface of the present-dayoceans. However at this depth the risk of being transported to surface waters in the mixed layer was high. The mixed layer mayhave been inhabited by a low diversity UV-resistant biota. Butit could have been numerically abundant. Repair capabilitiessimilar to Deinococcus radiodurans would be sufficient tosurvive in the mixed layer. Diversity may have beengreater in the region below the mixed layer and above the lightcompensation point corresponding to today's `deep chlorophyllmaximum'. During much of the Archean the air-water interface wasprobably an uninhabitable extreme environment for neuston. Thehabitability of some regions of the photic zone is consistentwith the evidence embodied in the geologic record, whichsuggests an oxygenated upper layer in the Archean oceans. Duringthe early Proterozoic, as ozone concentrations increased to acolumn abundance above 1 × 10¹⁷ cm^-2, UV stresswould have been reduced and possibly a greater diversity oforganisms could have inhabited the mixed layer. However,nutrient upwelling from newly emergent continental crusts mayhave been more significant in increasing total planktonic abundance inthe open oceans and coastal regions than photobiologicalfactors. The phohobiological environment of the Archean oceanshas implications for the potential cross-transfer of life betweenother water bodies of the early Solar System, possibly on earlyMars or the water bodies of a wet, early Venus.     

Effects of Ultraviolet Radiation on Amphibians: Field Experiments

SYNOPSIS. Numerous reports suggest that populations of amphibiansfrom a wide variety of locations are experiencing populationdeclines and/or range reductions. In some cases, unusually highegg mortality has been reported. Field experiments have beenused with increasing frequency to investigate ultraviolet radiationas one of the potential factors contributing to these declines.Results from field experiments illustrate that hatching successof eggs is hampered by ultraviolet radiation in a number ofspecies, while other species appear to be unaffected. Continuedmortality in early life-history stages may ultimately contributeto a population decline. Although UV-B radiation may not contributeto the population declines of all species, it may play a rolein the population decline of some species, especially thosethat lay eggs in open shallow water subjected to solar radiationand in those that have a poor ability to repair UV-induced DNAdamage.     

A Study of the Ultraviolet Radiation of Hybrid X-Pinches

Plasma Physics Reports - The results of an experimental study of hybrid X-pinches (HXPs) as sources of vacuum ultraviolet (VUV) radiation within the wavelength range of λ < 2000 Å...     

Ultraviolet Radiation Effects on Ehrlich Ascites Tumor Cells : Observations Using a Flying Spot Ultraviolet Microscope

A flying spot ultraviolet microscope, employing a fast scan and pulsed operation of the raster, has been used to induce radiation damage in ascites tumor slide cultures, and to study by time-lapse cinematography the progressive stages of cell damage. The cells observed came from a strain (EF₇) of the Ehrlich ascites carcinoma. Irradiated cells were found to show a characteristic syndrome of damage, involving blebbing at the cell surface, while control cells in the adjacent areas of the preparation remained unchanged. The end of the blebbing period is marked by swelling of the cells, and the time taken for this phenomenon to occur was used as a measure of the severity of the damage. It was found that the time required for swelling is dependent on the size of the dose employed, as well as on the sensitivity of the cells. This latter sensitivity was found to decline as the physiological age of the tumor increased. If ultraviolet illumination below 255 mµ is excluded, no symptoms of damage occur, even when very large doses are used. These observations are discussed in relation to the nature of the system in the cell which is affected.