Terrestrial leads compared with

However, these findings may reflect only a tiny fraction of the true therapeutic potential of marine actinomycetes. Recent culture-independent studies have shown that marine environments contain a high diversity of actinomycetes that are rarely, if ever, recovered by culture-dependent methods.8 Most of these unculturable actinomycetes have very different 16S rRNA sequences when compared with their terrestrial counterparts,6,9 and the ability to cultivate these novel actinomycetes will provide a new source for the discovery of novel drug leads. The future success of bioprospecting marine actinomycetes relies on our ability to isolate and grow novel actinomycetes from the marine environments. 

Photolysis of O3 in the Hartley bands leads to 02( Ag) production, with 60% formed vibrationally excited,and under atmospheric conditions quenching is found to be a rapid process. Rates of formation of 02( Ag) by this mechanism in the upper atmosphere of Venus have been calculated and compared with those determined by observations of the 02( Ag) emission at 1.27 pm for the values to agree, the previously accepted ozone concentrations would have to be revised upwards by a factor of 10. In the terrestrial atmosphere, the photolysis of 1 6q 1 8q at wavelengths between 170—205 nm could be an important source of odd oxygen in the high stratosphere and mesosphere, as solar radiation not absorbed by discrete 02 features may penetrate these regions and photolyse the minor isotopic constituent (present as 4% of naturally occurring 02). ... 

The expected adverse effects of increased levels of uv-B radiation include increased incidence of skin cancer in fairskinned races, decreased crop yields and a variety of stresses on terrestrial and aquatic ecosystems. Such effects have been considered in the past in connection with possible reduction of the ozone shield by the operation of fleets of SST airplanes [65] and by the continued release of chlorofluoromethanes used as refrigerants and as propellants in aerosol spray cans [66]. The information available is insufficient to allow quantification of most of these effects. Epidemiological data were used in the NAS study [1] to estimate that a 50 % ozone shield reduction lasting 3 years would lead to an increase of skin carcinoma and melanoma of 3-30 % at midlatitudes, with a geometric mean of about 10 %, that will persist for 40 years. This may be compared with the estimate made in the same study that during the first generation a 10,000 Mt war would increase the spontaneous cancer death rate by about 2 % as a result of exposure to low levels of ionizing radiation from radioactive fallout. 

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