Physiological responses of Acropora cervicornis to increased solar irradiance.

The effects of increased UV radiation (UV-B [280-320 nm] + UV-A [320-400 nm]; hereafter UVR) on the growth, production of photosynthetic pigments and photoprotective mycosporine-like amino acids (MAAs) were studied in the threatened Caribbean coral Acropora cervicornis transplanted from 20 to 1 m depth in La Parguera, Puerto Rico. The UVR exposure by the transplanted colonies was significantly higher than that at 20 m, while photosynthetically active radiation (PAR) only increased by 9%. Photosynthetic pigments, quantified with HPLC, as well as linear extension rates and skeletal densities, were significantly reduced 1 month after transplantation to 1 m depth, while MAAs increased significantly despite immediate paling experienced by transplanted colonies. While these colonies showed a significant reduction in photosynthetic pigments, there were no significant reductions in zooxanthellae densities suggesting photoacclimation of the coral's symbionts to the new radiation conditions. The results suggest that while corals might be able to survive sudden increases in UVR and PAR, their skeletal structure can be greatly debilitated due to a reduction in the photosynthetic capacity of their symbionts and a possible relocation of resources.

Relative Pigment Composition and Remote Sensing Reflectance of Caribbean Shallow-Water Corals.

Reef corals typically contain a number of pigments, mostly due to their symbiotic relationship with photosynthetic dinoflagellates. These pigments usually vary in presence and concentration and influence the spectral characteristics of corals. We studied the variations in pigment composition among seven Caribbean shallow-water Scleractinian corals by means of High Performance Liquid Chromatography (HPLC) analysis to further resolve the discrimination of corals. We found a total of 27 different pigments among the coral species, including some alteration products of the main pigments. Additionally, pigments typically found in endolithic algae were also identified. A Principal Components Analysis and a Hierarchical Cluster Analysis showed the separation of coral species based on pigment composition. All the corals were collected under the same physical environmental conditions. This suggests that pigment in the coral's symbionts might be more genetically-determined than influenced by prevailing physical conditions of the reef. We further investigated the use of remote sensing reflectance (Rrs) as a tool for estimating the total pigment concentration of reef corals. Depending on the coral species, the Rrs and the total symbiont pigment concentration per coral tissue area correlation showed 79.5-98.5% confidence levels demonstrating its use as a non-invasive robust technique to estimate pigment concentration in studies of coral reef biodiversity and health.

Hyperspectral sensing of disease stress in the Caribbean reef-building coral, Orbicella faveolata - perspectives for the field of coral disease monitoring.

The effectiveness of management plans developed for responding to coral disease outbreaks is limited due to the lack of rapid methods of disease diagnosis. In order to fulfill current management guidelines for responding to coral disease outbreaks, alternative methods that significantly reduce response time must be developed. Hyperspectral sensing has been used by various groups to characterize the spectral signatures unique to asymptomatic and bleached corals. The 2010 combined bleaching and Caribbean yellow band disease outbreak in Puerto Rico provided a unique opportunity to investigate the spectral signatures associated with bleached and Caribbean yellow band-diseased colonies of Orbicella faveolata for the first time. Using derivative and cluster analyses of hyperspectral reflectance data, the present study demonstrates the proof of concept that spectral signatures can be used to differentiate between coral disease states. This method enhanced predominant visual methods of diagnosis by distinguishing between different asymptomatic conditions that are identical in field observations and photographic records. The ability to identify disease-affected tissue before lesions become visible could greatly reduce response times to coral disease outbreaks in monitoring efforts. Finally, spectral signatures associated with the poorly understood Caribbean yellow band disease are presented to guide future research on the role of pigments in the etiology.

Niveles de luz ultravioleta ambiental asociados con apoptosis y necrosis en fibroblstos humanos / Environmental levels of ultraviolet light associated with apoptosis and necrosis in human fibroblstos

La apoptosis involucra una serie de episodios altamente organizados y programados que tienen por objeto mantener la estabilidad genómica eliminando células huésped defectuosas. El propósito de este estudio fue determinar las dosis umbral y los tiempos de exposición a UV-A y UV-B medioambientales suficientes como para producir apoptosis y necrosis en la células normales de una línea celular de fobroblastos humanos. Se midieron dosis de UV-A y UV-B durante un período de seis años con un radiómetro UV de cuatro canales. Se irradiaron los fibroblastos una vez utilizando Simuladores Solar UV Oriel con seis dosis de UV basados en el medio ambiente. Las dosis correspondieron a 0, 11, 19, 23 y 45 minutos de radiación ambiental de UV-A y UV-B al sol del mediodía en Puerto Rico. Se utilizó en método de unión de la anexina-V para diferenciar entre los fibroblastos normales y fibroblastos apoptóticos o necróticos. La dosis umbral de la apoptosis a la necrosis se halló entre 24-28 KJ/m2, correspondiente a los 19 y 23 minutos de exposición ambiental a UV-A y UV-B. Este estudio proporciona los primeros datos que especifican las dosis de umbral medioambientales de UV-A y UV-B en las que los fibroblastos humanos experimentas apoptosis y necrosis. Estos resultados pueden proporcionar valiosos umbrales dosis-respuesta de apoptosis y necrosis para futuros estudios mecanicistas y datos de línea de base para programas de prevención de cáncer de piel.