Giving Is Nicer than Taking: Preschoolers Reciprocate Based on the Social Intentions of the Distributor

Recent research has found that even preschoolers give more resources to others who have previously given resources to them, but the psychological bases of this reciprocity are unknown. In our study, a puppet distributed resources between herself and a child by taking some from a pile in front of the child or else by giving some from a pile in front of herself. Although the resulting distributions were identical, three- and five-year-olds reciprocated less generously when the puppet had taken rather than given resources. This suggests that children’s judgments about resource distribution are more about the social intentions of the distributor and the social framing of the distributional act than about the amount of resources obtained. In order to rule out that the differences in the children’s reciprocal behavior were merely due to experiencing gains and losses, we conducted a follow-up study. Here, three- and-five year olds won or lost resources in a lottery draw and could then freely give or take resources to/from a puppet, respectively. In this study, they did not respond differently after winning vs. losing resources.

Functional genomics of the Drosophila melanogaster X chromosome and the role of DWnt5 during development

The collection of X chromosome insertions (PX) lethal lines, which was isolated from a screen for essential genes on the X chromosome, was characterized by means of cloning the insertion sites, mapping the sites within genomic DNA and determination of the associated reporter gene expresssion patterns. The established STS flanking the P element insertion sites were submitted to EMBL nucleotide databases and their in situ data together with the enhancer trap expression patterns have been deposited in the FlyView database. The characterized lines are now available to be used by the scientific community for a detailed analysis of the newly established lethal gene functions. One of the isolated genes on the X chromosome was the Drosophila gene Wnt5 (DWnt5). From two independent screens, one lethal and three homozygous viable alleles were recovered, allowing the identification of two distinct functions for DWnt5 in the fly. Observations on the developing nervous system of mutant embryos suggest that DWnt5 activity affects axon projection pattern. Elevated levels of DWNT5 activity in the midline cells of the central nervous system causes improper establishment and maintenance of the axonal pathways. Our analysis of the expression and mutant phenotype indicates that DWnt5 function in a process needed for proper organization of the nervous system. A second and novel function of DWnt5 is the control of the body size by regulation of the cell number rather than affecting the size of cells. Moreover, experimentally increased DWnt5 levels in a post-mitotic region of the eye imaginal disc causes abnormal cell cycle progression, resulting in additional ommatidia in the adult eye when compared to wild type. The increased cell number and the effects on the cell cycle after exposure to high DWNT5 levels is the result of a failure to downregulate cyclin B and therefore the unsuccessful establishment of a G1 arrest.