The spectral distribution of biologically active solar radiation at Miami, Florida, USA

The spectral distribution of solar radiation was studied under different sky conditions during a 15- month period in Miami, Florida (USA), and over a latitudinal gradient at solar maximum. Spectroradiometric scans were characterized for total irradiance (300- 3000 nm) and the relative energetic and photon contributions of the following wavelength regions: UV-B (300-320nm); UV-A (320-400nm); B (400-500rim); PAR (400-700 nm); R (600-700 nm); and FR (728- 732 rim). Notable results include: (i) significantly higher UV-A energy fluxes than currently in use for laboratory experiments involving the biological effects of this bandwidth (values ranged from 33.6 to 55.4 W/m 2 in Miami over the year); (ii) marked diurnal shifts in B:R and R:FR, with elevated R:FR values in early morning: (iii) a strong correlation between R: FR and atmospheric water content; and (iv) unusually high PAR values under direct sunlight with cloudy skies (2484 ~tmot/2 per s)

Microbial Regulation in Gorgonian Corals

Gorgonian corals possess many novel natural products that could potentially mediate coral-bacterial interactions. Since many bacteria use quorum sensing (QS) signals to facilitate colonization of host organisms, regulation of prokaryotic cell-to-cell communication may represent an important bacterial control mechanism. In the present study, we examined extracts of twelve species of Caribbean gorgonian corals, for mechanisms that regulate microbial colonization, such as antibacterial activity and QS regulatory activity. Ethanol extracts of gorgonians collected from Puerto Rico and the Florida Keys showed a range of both antibacterial and QS activities using a specific <em>Pseudomonas aeruginosa</em> QS reporter,<em> </em>sensitive to long chain AHLs and a short chain <em>N</em>-acylhomoserine lactones (AHL) biosensor, <em>Chromobacterium violaceium</em>. Overall, the gorgonian corals had higher antimicrobial activity against non-marine strains when compared to marine strains. <em>Pseudopterogorgia americana</em>, <em>Pseusopterogorgia acerosa</em>, and <em>Pseudoplexuara flexuosa</em> had the highest QS inhibitory effect. Interestingly, <em>Pseudoplexuara porosa</em> extracts stimulated QS activity with a striking 17-fold increase in signal. The stimulation of QS by <em>P. porosa</em> or other elements of the holobiont may encourage colonization or recruitment of specific microbial species. Overall, these results suggest the presence of novel stimulatory QS, inhibitory QS and bactericidal compounds in gorgonian corals. A better understanding of these compounds may reveal insight into coral-microbial ecology and whether a therapeutic potential exists