RESUMEN
Chlorophyll d is a photosynthetic pigment that, based on chemical analyses, has only recently been recognized to be widespread in oceanic and lacustrine environments. However, the diversity of organisms harbouring this pigment is not known. Until now, the unicellular cyanobacterium Acaryochloris marina is the only characterized organism that uses chlorophyll d as a major photopigment. In this study we describe a new cyanobacterium possessing a high amount of chlorophyll d, which was isolated from waters around Heron Island, Great Barrier Reef (23° 26' 31.2â³ S, 151° 54' 50.4â³ E). The 16S ribosomal RNA is 2% divergent from the two previously described isolates of A. marina, which were isolated from waters around the Palau islands (Pacific Ocean) and the Salton Sea lake (California), suggesting that it belongs to a different clade within the genus Acaryochloris. An overview sequence analysis of its genome based on Illumina technology yielded 871 contigs with an accumulated length of 8 371 965 nt. Their analysis revealed typical features associated with Acaryochloris, such as an extended gene family for chlorophyll-binding proteins. However, compared with A. marina MBIC11017, distinct genetic, morphological and physiological differences were observed. Light saturation is reached at lower light intensities, Chl d/a ratios are less variable with light intensity and the phycobiliprotein phycocyanin is lacking, suggesting that cyanobacteria of the genus Acaryochloris occur in distinct ecotypes. These data characterize Acaryochloris as a niche-adapted cyanobacterium and show that more rigorous attempts are worthwhile to isolate, cultivate and analyse chlorophyll d-containing cyanobacteria for understanding the ecophysiology of these organisms.
Asunto(s)
Clorofila/análisis , Cianobacterias/química , Cianobacterias/aislamiento & purificación , Australia , Cromatografía Líquida de Alta Presión , Análisis por Conglomerados , Cianobacterias/citología , Cianobacterias/genética , ADN Bacteriano/química , ADN Bacteriano/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Luz , Microscopía Electrónica de Transmisión , Datos de Secuencia Molecular , Océano Pacífico , Filogenia , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Análisis EspectralRESUMEN
A kinematically complete measurement was made of the Coulomb dissociation of 8B nuclei on a Pb target at 83 MeV/nucleon. The cross section was measured at low relative energies in order to infer the astrophysical S factor for the 7Be(p,gamma)8B reaction. A first-order perturbation theory analysis including E1, E2, and M1 transitions was employed to extract the E1 strength relevant to neutrino-producing reactions in the solar interior. By fitting the measured cross section from E(rel) = 130 to 400 keV, we find S17(0) = 17.8(+1.4)(-1.2) eV b.
Asunto(s)
Anopheles/ultraestructura , Mutación , Animales , Anopheles/análisis , Larva , Microscopía ElectrónicaRESUMEN
A rickettsia-like organism causing high mortality and gross pathology has been found infecting over 40% of a population of the freshwater crustacean, Crangonyx (near) floridanus Bousfield, in Florida. This is the first report of a rickettsia-like organism from a strictly aquatic animal. Morphological and developmental stages of the organisms range in size and shape from small, dense bacilliform cells measuring 150 nm in diameter by 395 nm in length, to large sausage-shaped cells 0.5 by 3 mum.
