Roberto Abdala

Effect of nutrient supply on photosynthesis and pigmentation to short-term stress (UV radiation) in Gracilaria conferta (Rhodophyta).

The effects of increased photosynthetic active radiation (PAR), UV radiation (UVR), and nutrient supply on photosynthetic activity, pigment content, C:N ratio and biomass yield were studied in tank cultivated Gracilaria conferta (Rhodophyta). Electron transport rate (ETR) and biliprotein content were higher under high nutrient supply (HNS), obtained from fishpond effluents, compared to low nutrient supply (LNS), in contrast to mycosporine-like amino acids (MAAs) dynamic. The high MAA content in LNS-algae could be explained by higher UVR penetration in the thallus and by the competition for the use of nutrients with other processes. Effective quantum yield decreased after short-term exposure to high irradiance whereas full recovery in shade was produced only under slightly heat shock. UVA radiation provoked an additional decrease in photosynthesis under high water temperature. UVB radiation reversed UVAs negative effect mainly with HNS. Results support that nutrient-sufficiency help G. conferta to resist environmental changes as short-term temperature increase.

Photosynthetic performance and pigment content in the aquatic liverwort Riella helicophylla under natural solar irradiance and solar irradiance without ultraviolet light

Abstract The effects of solar radiation and solar radiation deprived of ultraviolet radiation (λ

Joint effects of climate warming and exotic litter (Eucalyptus globulus Labill.) on stream detritivore fitness and litter breakdown

Joint effects of climate warming and other stressors are potentially complex and difficult to predict. In stream ecosystems, exotic riparian species have the potential to alter leaf-shredding detritivorous invertebrate assemblages and leaf litter breakdown due to differences in the quality of litter inputs. This is the case for Eucalyptus plantations, which are widespread, occurring along riparian corridors of streams around the world. We hypothesised that the presence of Eucalyptus globulus (Labill.) litter (1) impairs detritivore fitness both directly (i.e., through leaf consumption) and indirectly (i.e., through leaf leachates in the water) and (2) impairs litter breakdown, (3) with stronger effects at higher temperatures. We tested these hypotheses in microcosm experiments with two detritivore species from two locations: the stonefly Diamphipnosis samali (Illies, 1960) in Chile and the caddisfly Calamoceras marsupus (Brauer 1865) in Spain. Eucalyptus leaves affected detritivore growth mainly by direct consumption, while the presence of both Eucalyptus leaves and leachates inhibited the breakdown of native litter. When both litter types were available, breakdown of Eucalyptus leaves was enhanced, possibly as a means of compensatory feeding. Increased temperature exacerbated the negative effect of Eucalyptus on native litter breakdown, possibly because it reduced detritivore survival. Our results add to the mounting evidence that joint effects of multiple stressors can be non-additive, and suggest that the sole presence of Eucalyptus leaves and leachates in the water may impact stream communities and ecosystem functions even if native litter is available, with further negative effects to be expected under a warmer climate.

Effect of dietary administration of Porphyridium cruentum on the respiratory burst activity of sole, Solea senegalensis (Kaup), phagocytes.

The stimulatory effect of the red microalga Porphyridium cruentum on respiratory burst activity of sole phagocytes was evaluated in vivo. Oral administration of a diet supplemented with lyophilized P. cruentum cells (10 g kg(-1)) stimulated respiratory burst activity after 4 weeks feeding in sole vaccinated with Photobacterium damselae subsp. piscicida bacterin.

Series temporales de medida de radiación solar ultravioleta y fotosintética en Málaga

Resumen Introduccion La radiacion ultravioleta es el principal factor etiopatogenico de las formas mas frecuentes del cancer de piel. En la provincia de Malaga es habitual la exposicion solar continuada, sobre todo por tener una alta afluencia de turismo y, ademas, por ser una region donde se desarrollan gran numero de actividades actinicas, tanto laborales como de ocio. Material y metodos Se determinan series temporales de medida de radiacion ultravioleta UVB, UVA y radiacion fotosinteticamente activa (PAR) solar en Malaga (36,5° N-4,7° O) utilizando la recien constituida Red de Medida de Radiacion Ultravioleta-Fotosintetica de Andalucia (UVIFAN) ( http://uvifan.scai.uma.es ). Resultados Se presentan ciclos anuales desde el ano 1997 hasta finales de 2001 de la dosis diaria total para las tres bandas de radiacion. Las dosis diarias maximas se observan en los meses estivales. El indice UV, que se alcanza en las horas centrales del dia, oscilo entre valores maximos de 7-8 durante los meses estivales y valores de 1-2 en los meses de invierno. Las relaciones de dosis PAR/UVA no varian a lo largo del ano, aunque la relacion UVB/UVA y UVB/PAR sigue un patron anual de variacion con valores maximos en los meses estivales, mientras que los valores mas bajos se obtuvieron durante los meses invernales. Conclusiones Estos datos confirman que en la provincia de Malaga, en los meses estivales existen niveles muy altos de radiacion UVA, UVB y PAR, por lo que es de suma importancia adoptar medidas especificas de fotoproteccion en esta epoca para evitar tanto las quemaduras a corto plazo, como la fotocarcinogenesis y el fotoenvejecimiento a largo plazo.

Biofiltration of fishpond effluents and accumulation of N-compounds (phycobiliproteins and mycosporine-like amino acids) versus C-compounds (polysaccharides) in Hydropuntia cornea (Rhodophyta)

The biofiltration capacity, biomass-yield and accumulation of N- and C-compounds of Hydropuntia cornea were analyzed. Algae were grown in different conditions for 28 d: outdoor and indoor, with or without fishpond effluents. N-uptake efficiency of these effluents was higher than 95% after 7 d both outdoors and indoors. N-enriched conditions reduced the extent of photoinhibition and increased the maximal quantum yield in H. cornea. The biomass-yield was higher in outdoor grown-algae after 7 d and decreased independently of the treatment after 28 d. N, acid polysaccharide (AP) and mycosporine-like amino acid (MAA)-yields decreased throughout the experiment in all conditions. The highest MAA-yield was observed in fishpond effluent outdoor-grown algae, indicating a positive effect of increased radiation on MAA accumulation. However, APs were higher under N-depleted conditions. The use of MAAs as UV-screening and antioxidants, and the use of AP as immunostimulants are discussed.

Screening of urocanic acid isomers in human basal and squamous cell carcinoma tumors compared with tumor periphery and healthy skin

Abstract:  Trans‐urocanic acid is a major chromophore for ultraviolet (UV) radiation in human epidermis. The UV induces photoisomerization of trans‐urocanic acid (tUCA) form to cis‐urocanic acid (cUCA) and has been reported as an important mediator in the immunosuppression induced by UV. This immunomodulation has been recognized as an important factor related to skin cancer development. This is the first time that UCA isomers have been measured in epidermis of skin biopsies from patients with squamous cell carcinoma (SCC) and with basal cell carcinoma (BCC) and compared with the tumor periphery and biopsies of healthy photoexposed and non‐photoexposed skin as controls. The UCA isomers were separated and quantified by high performance liquid chromatography. Analysis of UCA in healthy skin showed significant increase in total UCA content in non‐photoexposed body sites compared with highly exposed skins. In contrast, the percentage of cUCA was higher in photoexposed body sites. Maximal levels of cUCA were found in cheek, forehead and forearm and lower levels in abdomen and thigh. No differences were found in total UCA concentration between the tumor samples and healthy photoexposed skin. However, differences were found in relation between isomers. Higher levels of cUCA were detected in SCC biopsies (44% of total UCA) compared with samples of BCC and that of healthy photoexposed skin (30%). These results suggest that the UV radiation exposure, a main factor in development of SCC can be mediated, apart from direct effect to cells (DNA damage), by immunosuppression pathways mediated by high production of cUCA.