Androgenetic reproduction in a freshwater diploid clam Corbicula fluminea (Bivalvia: Corbiculidae).

Two shell color types of the exotic bivalve Corbicula fluminea were collected in Kyoto city, Japan. DNA microfluorometry revealed that both types were diploids with non-reductional spermatozoa. Maternal chromosomes were found to be extruded as two polar bodies at the first meiosis, and the second meiosis could not be observed.

Selective and delay adaptation of human saccades.

The consistently triggered step back of a target during primary saccades of a human subject induced a gradual change in gain, the ratio of the saccade amplitude to the target eccentricity. After a few hundred trials, subjects were able to foveate the displaced target in a single saccade. Presentation of a displaced target showed that human memory guided saccades have gain adaptation just like the well-established adaptation of visually guided saccades.