The 2.2 A crystal structure of a pocilloporin pigment reveals a nonplanar chromophore conformation

Reef-building corals contain host pigments, termed pocilloporins, that function to regulate the light environment of their resident microalgae by acting as a photoprotectant in excessive sunlight. We have determined the crystal structure of an intensely blue, non-fluorescent pocilloporin to 2.2 Angstrom resolution and a genetically engineered fluorescent variant to 2.4 Angstrom resolution. The pocilloporin chromophore structure adopts a markedly different conformation in comparison with the DsRed chromophore, despite the chromophore sequences (Gin-Tyr-Gly) being identical; the tyrosine ring of the pocilloporin chromophore is noncoplanar and in the trans configuration. Furthermore, the fluorescent variant adopted a noncoplanar chromophore conformation. The data presented here demonstrates that the conformation of the chromophore is highly dependent on its immediate environment.

The production, purification and crystallization of a pocilloporin pigment from a reef-forming coral

Reef-building corals contain fluorescent pigments termed pocilloporins that function by regulating the light environment of coral and acting as a photoprotectant in excessive sunlight. These pocilloporins are related to the monomeric green fluorescent protein and the tetrameric DsRed fluorescent proteins, which have widespread use as biotechnological tools. An intensely blue-coloured pocilloporin, termed Rtms5, was expressed in Escherichia coli, purified and crystallized. Rtms5 was shown to be tetrameric, with deep blue crystals that diffract to 2.2 Angstrom resolution and belong to space group I4(1)22. The colour of this pocilloporin was observed to be sensitive to pH and a yellow (pH 3.5) and a red form (pH 4.5) of Rtms5 were also crystallized. These crystals belong to space group P4(2)22 and diffract to 2.4 Angstrom resolution or better.

A randomized controlled trial to assess sunscreen application and beta carotene supplementation in the prevention of solar keratoses

Background: Solar keratoses (SKs) are among the strongest determinants of skin cancer, but little is known about the success of measures to control these common skin tumors. Objective: To determine whether daily sunscreen application and/or beta carotene supplementation retards the rate of occurrence of SKs in adults in the medium term. Design: Randomized controlled trial conducted between February 1992 and August 1996. Setting: General community of the subtropical township of Nambour, Australia (latitude, 26degrees south). Participants: A total of 1621 adults aged 25 to 74 years. Interventions: Participants were randomized to daily use of sunscreen (application of a high-protection sunscreen to their head, neck, arms, and hands every morning) or application of sunscreen at their usual discretionary rate. They were also randomly assigned to take either one 30-mg tablet of beta carotene or one placebo tablet each day. Main Outcome Measure: Change in the prevalent number of SKs in the intervention group relative to change in the control group. Results: The ratio of SK counts in 1994 relative to 1992 was lower in people randomized to daily sunscreen use (1.20; 95% confidence interval, 1.04-1.39) than in those randomized to discretionary sunscreen use (1.57; 95% confidence interval, 1.35-1.84). This 24% reduction is equivalent to the prevention of an average of I additional SK per person over that time. A reduction in the rate of change of SK prevalence was also seen in the sunscreen intervention group relative to the discretionary sunscreen group between 1994 and 1996, but it was not significant. No effect on the rate of change of prevalent SK counts was seen among those taking beta carotene supplements relative. to those taking placebo tablets. Conclusions: Daily application of sunscreen retarded the rate of SK acquisition among adults in a subtropical environment, while a beta carotene supplementation of 30 mg/d had no influence on the occurrence of SKs.

Merkel-cell carcinoma of the skin

Merkel-cell carcinoma (MCC) is a rare form of skin cancer of neuroendocrine origin that has been described as the most aggressive cutaneous malignancy. The cell of origin is thought to be the Merkel cell or skin-pressure receptor. It has the propensity for dermal-lymphatic invasion, and nodal and haematogenous spread. Factors that have been implicated in its cause include exposure to sunlight and immunosuppression. The tumour has many similarities to small-cell carcinoma of the lung, with intrinsic sensitivity to ionising radiation and chemotherapy, and an aggressive metastatic potential. The best treatment outcomes can be achieved with early diagnosis and the integration of surgery, radiation, and chemotherapy. The treatment challenges for the clinician are often enormous because many of the patients are elderly and because lesions occur in difficult sites such as the head and neck region and the lower leg.

Testing the 'photoinhibition' model of coral bleaching using chemical inhibitors

Explants of the hard coral Seriatopora hystrix were exposed to sublethal concentrations of the herbicide diuron DCMU (N'-(3,4-dichlorophenyl,-N,N-dimethylurea)) and the heavy metal copper. Pulse amplitude modulated (PAM) chlorophyll fluorescence techniques were used to assess the effects on the photosynthetic efficiency of the algal symbionts in the tissue (in Symbio), and chlorophyll fluorescence and counts of symbiotic algae (normalised to surface area) were used to assess the extent of coral bleaching. At 30 mug DCMU l(-1), there was a reduction in both the maximum effective quantum yield (DeltaF/F-m') and maximum potential quantum yield (F-v/F-m) of the algal symbionts in symbio. Corals subsequently lost their algal symbionts and discoloured (bleached), especially on their upper sunlight-exposed surfaces. At the same DCMU concentration but under low light (5% of growth irradiance), there was a marked reduction in DeltaF/F-m' but only a slight reduction in F-v/F-m and slight loss of algae. Loss of algal symbionts was also noted after a 7 d exposure to concentrations as low as 10 mug DCMU l(-1) under normal growth irradiance, and after 14 d exposure to 10 mug DCMU l(-1) under reduced irradiance. Collectively the results indicate that DCMU-induced bleaching is caused by a light-dependent photoinactivation of algal symbionts, and that bleaching occurs when F-v/F-n, (measured 2 h after sunset) is reduced to a value of less than or equal to 0.6. Elevated copper concentrations (60 mug Cu l(-1) for 10 h) also induced a rapid bleaching in S. hystrix but without affecting the quantum yield of the algae in symbio. Tests with isolated algae indicated that substantially higher concentrations (300 mug Cu l(-1) for 8 h) were needed to significantly reduce the quantum yield. Thus, copper-induced bleaching occurs without affecting the algal photosynthesis and may be related to effects on the host (animal). It is argued that warm-water bleaching of corals resembles both types of chemically induced bleaching, suggesting the need for an integrated model of coral bleaching involving the effect of temperature on both host (coral) and algal symbionts.

Seasonal variations of phenolic compounds in Australia-grown tea (Camellia sinensis)

Seasonal variations of phenolic compounds in fresh tea shoots grown in Australia were studied using an HPLC method. Three principal tea flavanols [epigallocatechin gallate (EGCG), epicatechin gallate (ECG), and epigallocatechin (EGC)] and four grouped phenolics [total catechins (Cs), total catechin gallates (CGs), total flavanols (Fla), and total polyphenols (PPs)] in fresh tea shoots were analyzed and compared during the commercial harvest seasons from April 2000 to May 2001. The levels of EGCG, ECG, and CGs in the fresh tea shoots were higher in the warm months of April 2000 (120.52, 34.50, and 163.75 mg/g, respectively) and May 2000 (128.63, 44.26, and 183.83 mg/g, respectively) and lower during the cool months of July 2000 (91.39, 35.16, and 132.30 mg/g, respectively), August 2000 (91.31, 31.56, and 128.64 mg/g, respectively), and September 2000 (96.12, 33.51, and 136.90 mg/g, respectively). Thereafter, the levels increased throughout the warmer months from October to December 2000 and remained high until May 2001. In the warmer months, the levels of EGCG, ECG, and CGs were in most cases significantly higher (P < 0.05) than those in the samples harvested in the cooler months. In contrast, the levels of EGC and Cs were high and consistent in the cooler months and low in the warmer months. The seasonal variations of the individual and grouped catechins were significant (P < 0.05) between the cooler and warmer months. This study revealed that EGCG and ECG could be used as quality descriptors for monitoring the seasonal variations of phenolics in Australia-grown tea leaves, and the ratio (EGCG + ECG)/EGC has been suggested as a quality index for measuring the differences in flavanol levels in fresh tea shoots across the growing seasons. Mechanisms that induce seasonal variations in tea shoots may include one or all three of the following environmental conditions: day length, sunlight, and/or temperature, which vary markedly across seasons. Therefore, further studies under controlled conditions such as in a greenhouse may be required to direct correlate flavonoid profiles of green tea leaves with their yields and also to with conditions such as rainfall and humidity.

Diel 'tuning' of coral metabolism: physiological responses to light cues

Hermatypic-zooxanthellate corals track the diel patterns of the main environmental parameters temperature, UV and visible light - by acclimation processes that include biochemical responses. The diel course of solar radiation is followed by photosynthesis rates and thereby elicits simultaneous changes in tissue oxygen tension due to the shift in photosynthesis/respiration balance. The recurrent patterns of sunlight are reflected in fluorescence yields, photosynthetic pigment content and activity of the two protective enzymes superoxide dismutase (SOD) and catalase (CAT), enzymes that are among the universal defenses against free radical damage in living tissue. All of these were investigated in three scleractinian corals: Favia favus, Plerogyra sinuosa and Goniopora lobata. The activity of SOD and CAT in the animal host followed the course of solar radiation, increased with the rates of photosynthetic oxygen production and was correlated with a decrease in the maximum quantum yield of photochemistry in Photosystem H (PSII) (Delta F'/F-m'). SOD and CAT activity in the symbiotic algae also exhibited a light intensity correlated pattern, albeit a less pronounced one. The observed rise of the free-radical-scavenger enzymes, with a time scale of minutes to several hours, is an important protective mechanism for the existence and remarkable success of the unique cnidarian-dinoflagellate associations, in which photosynthetic oxygen production takes place within animal cells. This represents a facet of the precarious act of balancing the photosynthetic production of oxygen by the algal symbionts with their destructive action on all living cells, especially those of the animal host.

Cone photoreceptor oil droplet pigmentation is affected by ambient light intensity

The cone photoreceptors of many vertebrates contain spherical organelles called oil droplets. In birds, turtles, lizards and some lungfish the oil droplets are heavily pigmented and function to filter the spectrum of light incident upon the visual pigment within the outer segment. Pigmented oil droplets are beneficial for colour discrimination in bright light, but at lower light levels the reduction in sensitivity caused by the pigmentation increasingly outweighs the benefits generated by spectral tuning. Consequently, it is expected that species with pigmented oil droplets should modulate the density of pigment in response to ambient light intensity and thereby regulate the amount of light transmitted to the outer segment. In this study, microspectrophotometry was used to measure the absorption spectra of cone oil droplets in chickens (Gallus gallus domesticus) reared under bright (unfiltered) or dim (filtered) sunlight. Oil droplet pigmentation was found to be dependent on the intensity of the ambient light and the duration of exposure to the different lighting treatments. In adult chickens reared in bright light, the oil droplets of all cone types (except the violet-sensitive single cones, whose oil droplet is always non-pigmented) were more densely pigmented than those in chickens reared in dim light. Calculations show that the reduced levels of oil droplet pigmentation in chickens reared in dim light would increase the sensitivity and spectral bandwidth of the outer segment significantly. The density of pigmentation in the oil droplets presumably represents a trade-off between the need for good colour discrimination and absolute sensitivity. This might also explain why nocturnal animals, or those that underwent a nocturnal phase during their evolution, have evolved oil droplets with low pigment densities or no pigmentation or have lost their oil droplets altogether.

Population differences in finger-length ratios: Ethnicity or latitude?

The relative length of the second and fourth fingers (the 2D:4D ratio) has been taken to be an indicator of prenatal exposure to testosterone, and hence possibly relevant to sexual orientation and other sex-differentiated behaviors. Studies have reported a difference in this ratio between Caucasian males in Britain and in the U.S.: higher average 2D:4D ratios were obtained in Britain. This raises the question of whether differences among different Caucasian gene pools were responsible or whether some environmental variable associated with latitude might be involved (e.g., exposure to sunlight or different day-length patterns). This question was explored by examining 2D:4D ratios for an Australian adolescent sample. The Australians were predominantly of British ancestry, but lived at distances from the equator more like those of the U.S. studies. The Australian 2D:4D ratios resembled those in Britain rather than those in the U.S., tending to exclude hypotheses related to latitude and making differences in gene pools a plausible explanation.

Sensory Processing in Aquatic Environments

Research on sensory processing or the way animals see, hear, smell, taste, feel and electrically and magnetically sense their environment has advanced a great deal over the last fifteen years. This book discusses the most important themes that have emerged from recent research and provides a summary of likely future directions. The book starts with two sections on the detection of sensory signals over long and short ranges by aquatic animals, covering the topics of navigation, communication, and finding food and other localized sources. The next section, the co-evolution of signal and sense, deals with how animals decide whether the source is prey, predator or mate by utilizing receptors that have evolved to take full advantage of the acoustical properties of the signal. Organisms living in the deep-sea environment have also received a lot of recent attention, so the next section deals with visual adaptations to limited light environments where sunlight is replaced by bioluminescence and the visual system has undergone changes to optimize light capture and sensitivity. The last section on central co-ordination of sensory systems covers how signals are processed and filtered for use by the animal. This book will be essential reading for all researchers and graduate students interested in sensory systems.

A RELAÇÃO ENTRE RELIGIÃO E SAÚDE NO DISCURSO DE ELLEN G. WHITE (1827-1915)

O objetivo principal da pesquisa encetada foi o de ressaltar a importância do discurso de Ellen White, uma importante líder religiosa do século XIX, nos Estados Unidos da América, para a formação de um estilo e prática de vida, que ainda hoje caracteriza os adventistas do sétimo dia no que se refere a saúde. Outro, não menos importante objetivo, foi o de comparar os principais conceitos de Ellen White sobre saúde e estilo de vida com algumas preocupações científicas e acadêmicas contemporâneas. Para isso, este trabalho mostra como a lista de oito remédios naturais propostos por White sumarizam o ideal de uma vida saudável ainda praticada por milhões de adventistas, 100 anos após a morte de sua Profetiza: ar puro, água, alimentação adequada, luz solar, exercícios físicos, repouso, abstinência, e confiança em Deus. Os conselhos de White foram contrastados com várias práticas culturais que relacionam religião e saúde, levando-nos à conclusão que a cultura adventista tem se mostrado como a mais adequada na salvaguarda da saúde. Isto porque White apresentou uma síntese de elementos da cultura judaica, cristã e ocidental. Nesse sentido, as suas orientações garantem-lhe um lugar privilegiado no movimento de reforma da saúde nos Estados Unidos que ocorreu naquele País na segunda metade do século XIX. Muitos de seus conselhos estão sendo atualmente colocados em prática por todos aqueles que se preocupam com a saúde, longevidade, e a adequação do estilo de vida com as regras inspiradas na natureza e numa espiritualidade sadia.

An ideal ocular nutritional supplement?

The role of nutritional supplementation in prevention of onset or progression of ocular disease is of interest to health care professionals and patients. The aim of this review is to identify those antioxidants most appropriate for inclusion in an ideal ocular nutritional supplement, suitable for those with a family history of glaucoma, cataract, or age-related macular disease, or lifestyle factors predisposing onset of these conditions, such as smoking, poor nutritional status, or high levels of sunlight exposure. It would also be suitable for those with early stages of age-related ocular disease. Literature searches were carried out on Web of Science and PubMed for articles relating to the use of nutrients in ocular disease. Those highlighted for possible inclusion were vitamins A, B, C and E, carotenoids beta-carotene, lutein, and zeaxanthin, minerals selenium and zinc, and the herb, Ginkgo biloba. Conflicting evidence is presented for vitamins A and E in prevention of ocular disease; these vitamins have roles in the production of rhodopsin and prevention of lipid peroxidation respectively. B vitamins have been linked with a reduced risk of cataract and studies have provided evidence supporting a protective role of vitamin C in cataract prevention. Beta-carotene is active in the prevention of free radical formation, but has been linked with an increased risk of lung cancer in smokers. Improvements in visual function in patients with age-related macular disease have been noted with lutein and zeaxanthin supplementation. Selenium has been linked with a reduced risk of cataract and activates the antioxidant enzyme glutathione peroxidase, protecting cell membranes from oxidative damage while zinc, although an essential component of antioxidant enzymes, has been highlighted for risk of adverse effects. As well as reducing platelet aggregation and increasing vasodilation, Gingko biloba has been linked with improvements in pre-existing field damage in some patients with normal tension glaucoma. We advocate that vitamins C and E, and lutein/zeaxanthin should be included in our theoretically ideal ocular nutritional supplement.

Seasonal growth of foliose lichens in successive years in South Gwynedd, Wales

The aim of this study was to test the hypothesis that differences in the pattern of seasonal growth in foliose lichens from year to year were determined by yearly differences in the distribution of rainfall, shortwave radiation and temperature. Hence, the radial growth of Parmelia conspersa (Ehrh. Ex Ach.) Ach. , P. glabratula ssp. fuliginosa (Fr. ex Duby) Laund. and Physcia orbicularis (Neck) Poetsch. was studied on slate fragments over 34 successive months in an area of South Gwynedd, Wales. U.K. Similarities and differences were observed in the pattern of seasonal growth in the three species. Periods of maximum growth of a species occurred in different seasons in successive years. Correlation and multiple regression analysis suggested that total rainfall per month was the most important climatic variable positively correlated with monthly growth. Significant positive correlations were found in some growth periods with number of raindays per month, average wind speed and maximum and minimum temperature. Total number of sunshine hours per month and the frequency of ground frosts were negatively correlated with monthly growth in some growth periods. For each species, monthly radial growth was correlated with different climatic variables in each growth period. Hence, the results support the hypothesis in that periods of maximum growth can occur in any season in South Gwynedd and depend on (1) the distribution of periods of high total rainfall and (2) whether or not these periods coincide with periods of maximum sunlight.

The development of a solar wall module using a selective surface

A need was indicated for the identification of a possible new solar energy product to improve the sales potential of a metal film with a selective surface, manufactured by the industriaI sponsor of this project (INCO). A possible way of overcoming the disadvantageous economics of solar energy collection was identified. This utilised the collection of solar energy by the walls of buildings constructed in such a manner as to allow the transfer of energy into the building, whilst providing adequate thermal insulation in the absence of sunlight. The actual collection element of the wall, being metallic, is also capable of performing the function of a low temperature heating .system in the absence of sunlight. As a result of this, the proposed system, by displacing both the wall and centraI heating system which would otherwise be necessary, demonstrates economic benefits over systems which are constructed solely for the purpose of collecting solar energy. The necessary thermodynamic and meteorological. characteristics and data: are established, and applied to a typical urban site in the North of England, for a typical average year, with and without a shading device incorporated into the construction. It is concluded that the proposed system may offer considerable benefit in reducing the effective heating season in all orientations of wall.

Energy saving and solar electricity in fan-ventilated greenhouses

Greenhouse cultivation is an energy intensive process therefore it is worthwhile to introduce energy saving measures and alternative energy sources. Here we show that there is scope for energy saving in fan ventilated greenhouses. Measurements of electricity usage as a function of fan speed have been performed for two models of 1.25 m diameter greenhouse fans and compared to theoretical values. Reducing the speed can cut the energy usage per volume of air moved by more than 70%. To minimize the capital cost of low-speed operation, a cooled greenhouse has been built in which the fan speed responds to sunlight such that full speed is reached only around noon. The energy saving is about 40% compared to constant speed operation. Direct operation of fans from solar-photovoltaic modules is also viable as shown from experiments with a fan driven by a brushless DC motor. On comparing the Net Present Value costs of the different systems over a 10 year amortization period (with and without a carbon tax to represent environmental costs) we find that sunlight-controlled system saves money under all assumptions about taxation and discount rates. The solar-powered system, however, is only profitable for very low discount rates, due to the high initial capital costs. Nonetheless this system could be of interest for its reliability in developing countries where mains electricity is intermittent. We recommend that greenhouse fan manufacturers improve the availability of energy-saving designs such as those described here.