UV-B radiation

For the first time, the photosynthetic performance of field-grown macroalgae from the Magellan Strait was evaluated with respect to their photoadaptation in the field and acclimation potential to ultraviolet radiation. Five macroalgal species were collected in the eulittoral and the upper sublittoral: Ulva intestinalis, Porphyra columbina, Adenocystis utricularis, Desmarestia confervoides and D. ligulata. Photosynthesis vs. irradiance (P-I) curves of macroalgae

The depletion of the stratospheric ozone layer leads to an increase in the level of ultraviolet-B radiations reaching the Earth's surface. UV-B radiations are known to have damaging effects on all forms of life. In plants, the UV-B exposure leads to the generation of reactive oxygen species (ROS), eventually resulting in oxidative stress. ROS induce lipid peroxidation of biological membranes, destroy the natural lipid-soluble antioxidants, and alter the expression of several genes through nonspecific signaling pathways. The integration of the thylakoid membrane appears to be much more sensitive than the activities of the photosynthetic components bound within. However, the decrease of mRNA transcripts in the photosynthetic complexes and other chloroplast proteins are among the early events of UV-B damage. Other genes, encoding defense-related proteins are rapidly upregulated under UV-B irradiation. UV-B radiation induced production of ROS, increased the antioxidant capacity and thus, minimized the magnitude of negative impact of UV-B on plants. Specific signaling pathway includes the UVR8 component that regulates the expression of a set of genes essential for the protection of plant against UV-B. This chapter comprises information regarding the UV-B perception, signal transduction, regulation of gene expression, ROS formation, and its metabolism from various studies performed under growth chamber, green house, and field conditions.

Las plantas son las encargadas de la realización de procesos metabólicos esenciales. Ellas tienen la posibilidad de generar oxígeno y compuestos alimenticios a través de la  fotosíntesis a partir del agua, el dióxido de carbono y la energía solar. Por lo tanto, son esenciales para el mantenimiento de la vida en el planeta. El lugar donde se desarrollan, se convierte en la fuente de información que determinará la cantidad y calidad de la cosecha. La luz es heterogénea y cambiante de ahí que las plantas se hallan expuestas a radiaciones adversas para la realización de sus procesos metabólicos. Es así, como han desarrollado una serie de adaptaciones estructurales y fisiológicas que les permiten soportar y aprovechar la radiación disponible. La energía solar ultravioleta es inhibidora, y puede ocasionar algunos desbalances biosintéticos, que a su vez, mediante las rutas del metabolismo  secundario, podrían generar propiedades especiales imprimiendo tipicidad en frutos producidos en climas fríos tropicales, con características regionales o de denominación de origen. La biosíntesis secundaria, suele hallarse restringida a fases específicas del desarrollo de la planta y a situaciones  de estrés; condiciones que inducen a la expresión de genes que codifican varias enzima de la ruta biosintética de compuestos fenilpropanoides

If you ask someone: “What is it most essential to have in life?” you will undoubtedly receive the response: “good health”.
New findings in the medical field show that we need to review our commonly shared understanding of the fear of exposure to sunlight and its association with carcinogenesis (creation of cancer). There is a strong indication that inadequate levels of vitamin D in the human body can be the cause of some terminal illnesses and contribute to poor health.

Στην άσκηση αυτή θα πραγματοποιηθεί μελέτη της υπεριώδους ακτινοβολίας UVB, διαμέσου μετρήσεων του δείκτη UV (UV Index) ανέφελης ημέρας σε χρονικό πλαίσιο μίας ώρας. Ακόμη, θα υπολογιστεί η λαμβανόμενη δόση ακτινοβολίας συναρτήσει διαφόρων τύπων ανθρώπινου δέρματος και θα εκτιμηθεί το πάχος σε mm της ολικής στήλης όζοντος από την οποία πέρασε η ακτινοβολία, πριν να καταφτάσει στην επιφάνεια της Γης και στον δέκτη του οργάνου.

The health risks associated with ozone depletion will principally be those due to increased ultraviolet B (UV-B) radiation in the environment, i.e., increased damage to the eyes, the immune system, and the skin. Some new risks may also be introduced with the increased use of alternatives to the ozone-depleting substances (ODSs). Quantitative risk estimates are available for some of the UV-B-associated effects, e.g., cataract and skin cancer; however, the data are insufficient to develop similar estimates for effects such as immunosuppression and the toxicity of alternatives. Ocular damage from UV exposures includes effects on the cornea, lens, iris, and associated epithelial and conjunctival tissues. The most common acute ocular effect of environmental ultraviolet radiation (UVR) is photokeratitis. Also known as snowblindness in skiers, this condition also occurs in other outdoor recreationists. Chronic eye conditions likely to increase with ozone depletion include cataract, squamous cell carcinoma, ocular melanoma, and a variety of corneal/conjunctival effects, e.g., pterygium and pinguecula. Suppression of local (at the site of UV exposure) and systemic (at a distant, unexposed site) immune responses to a variety of antigens has been demonstrated in both humans and animals exposed to UV-B. In experiments with animals these effects have been shown to worsen the course/ outcome of some infectious diseases and cancers. There is reasonably good evidence that such immunosuppression plays a role in human carcinogenesis; however, the implications of such immunosuppression for human infectious diseases are still unknown. In light-skinned populations, exposure to solar UVR appears to be the most important environmental risk factor for basal and squamous cell carcinomas and cutaneous melanoma. Originally it was believed that total accumulated exposure to UVR was the most important environmental factor in determining risk for these tumors. Recent information now suggests that only squamous cell carcinoma risk is related to total exposure. In the cases of both basal cell carcinoma and melanoma, new information suggests that increases in risk are tied to early exposures (before about age 15), particularly those leading to severe sunburns. Testing of a number of the chlorofluorocarbon (CFC) alternatives indicates that most of these chemicals have low acute toxicity, and low to moderate chronic toxicity. Some chemicals that were originally proposed as alternatives have been dropped from consideration because these tests raised concerns about toxicity and/or manufacturing difficulties. In one instance, high accidental occupational exposure was associated with liver damage, underlining the need for care in the use of these substitutes. Recent quantitative risk estimates have been developed for cataract, melanoma, and all skin cancers combined. These estimates indicate that under the Montreal Adjustments, cataract and skin-cancer incidence will peak mid-century at additional incidences of just under 3 per 100000 and about 7 per 100000, respectively.

Glucotropaeolin and total phenolic concentrations were assessed in three different organs (inflorescences, leaves, unripe seeds) of nasturtium (Tropaeolum majus L.), which are consumed as herbal plant products, in order to determine the effect of short-term and moderate UV-B exposure as targeted postharvest stress treatment on the secondary plant metabolism. For this purpose, nasturtium plants were subjected to two UV-B radiation levels: 0.075 and 0.15 W h m− 2. The results clearly demonstrate that the plant response to short-term and moderate UV-B exposure is organ-, plant tissue age-, and phytochemical-specific and that these factors influence a change of secondary metabolism as revealed by the different phytochemical concentration levels elicited.In food processing UV treatment is mainly attributed to disinfection. This study examined the feasibility of short-term and moderate UV-B application as emerging technology for enhancing health-promoting phytochemicals in freshly consumed plant products (inflorescences, leaves, unripe seeds) demonstrated by the herbal plant nasturtium. Optimizing phytochemical concentration by targeted postharvest UV-B applications will add health value and subsequently generate new opportunities for growers and processors by achieving the health-oriented food market.

A new series of measurements including global and UV radiation was initiated in 1994 at Penang. These high quality data were used to study diurnal and seasonal variations. The mean daily total UV-B and global radiation is about 1.43×104 J and 1.77×107 J, respectively. Maximum radiation values for both the UV-B and global radiation are received in March and September. The daily total global radiation shows a bigger seasonal variation than UV-B radiation. On clear days, the erythemal UV radiation flux is in the high or extreme range for about 5 h beginning at around 1030 hours throughout the year. Penang (5.3°N) and Natal (6°S) are found to exhibit similar daily maximum erythemal UV irradiance values. A simple empirical relationship for the noontime UV-B flux and global irradiance in the equatorial/tropical regions has been established.

Plants possess a number of defence systems against plant-stress related inflictions such as natural, but at times excessive UV-B radiation. One protection mechanism is the altered synthesis of antioxidative substances like flavonoids, carotenoids, and ascorbic acid. Antioxidants have gained wide recognition for their health promoting actions in human body metabolism. Plants grown under protected cultivation do not receive any UV-B

We present an improved method for genomic DNA extraction from cyanobacteria by updating the earlier method from our group (Sinha et al. 2001) that does not require lysozyme treatment or sonication to lyse the cells. This method use lysis buffer to lyse the cells and also skips the initial treatments to remove the exopolysaccharides or to break the clumps. To

— The investigation was carried out to find out whether enhanced UVB radiation increases the synthesis of secondary metabolites in some plants grown under tropical region. Like tropical plant temperate plant also grown successfully in the tropical region. Tropical plants are thought to have an inherent resistance to abiotic stress. The abiotic stress that enhances the ability of the plant by increasing the content of the secondary bioactive components. While the plants exposed to enhanced UVB radiation in the field condition, the synthesis of secondary pigments like flavonoids and anthocyanin level varied among species. In radish and beetroot the synthesis of flavonoid and anthocyanin the content was increased, whereas, in the onion and carrot, the level of synthesis of secondary pigment was less. But compared to ambient plants the UVB the irradiated the plant has more secondary pigment. So it proves that the UVB radiation increases the synthesis of secondary pigment content by activating the defence mechanism and to protect plants against UVB damage.

Scanning electron microscopic (SEM) study of gills of Catla catla catla (17-day-old) exposed to UV-B radiation (145 µW cm−2 at the water surface) for three different exposure times: 5, 10 and 15 min was conducted. Fish without UV-B exposure served as control. UV-B radiation damaged both gill filaments and lamellae. The intensity of damage was minimal in 5 min exposed fish, followed by 10 min exposed fish and maximal in 15 min. The gill epithelium was severely damaged in 15 min irradiated fish compared to control. Pavement cells (PVCs) were damaged and the numbers of microridges within PVCs decreased. The deep boundary of PVC was not clear. In some area of gill epithelium, PVCs were destroyed and mitochondrion-rich cells (MRCs) were exposed. The 5 min exposure reduced the number of microridges in the PVCs, but the boundary of PVCs was still visible. MRCs in the gill epithelium were not exposed in 5 min exposed fish. The damage to PVCs and subsequent exposure of MRCs in UV-B irradiated fish may hamper respiratory functions and disturb osmoregulation in catla.