Coherent control of the efficiency of an artificial light-harvesting complex

Coherent control over the branching ratio between competing pathways for energy flow is realised for artificial light-harvesting complex. Direct insights to the mechanism featuring quantum interference of a low-frequency mode are presented.</p

Karyotypic conservatism in samples of Characidium cf. zebra (Teleostei, Characiformes, Crenuchidae): Physical mapping of ribosomal genes and natural triploidy

Basic and molecular cytogenetic analyses were performed in specimens of Characidium cf. zebra from five collection sites located throughout the Tietê, Paranapanema and Paraguay river basins. The diploid number in specimens from all samples was 2n = 50 with a karyotype composed of 32 metacentric and 18 submetacentric chromosomes in both males and females. Constitutive heterochromatin was present at the centromeric regions of all chromosomes and pair 23, had additional interstitial heterochromatic blocks on its long arms. The nucleolar organizer regions (NORs) were located on the long arms of pair 23, while the 5S rDNA sites were detected in different chromosomes among the studied samples. One specimen from the Alambari river was a natural triploid and had two extra chromosomes, resulting in 2n = 77. The remarkable karyotypic similarity among the specimens of C. cf. zebra suggests a close evolutionary relationship. On the other hand, the distinct patterns of 5S rDNA distribution may be the result of gene flow constraints during their evolutionary history

New records and extension of the known distribution of some freshwater shrimps in Brazil

Freshwater prawns are distributed in rivers and streams of inland and brackish waters throughout America. In Brazilian waters are registered 35 species into 4 families (Atyidae, Euryrhynchidae, Palaemonidae, and Sergestidae). Information about the geographic distribution of this fauna is scattered in the literature and frequently not founded on documented data in scientific collections. Here we examined a series of specimens and detected several new records and extension of the known distribution of some freshwater shrimps in Brazil