We demonstrated the following by studying these subgroup molecules. We examined the expression pattern of NB-3 transcripts in mouse brain by in situ hybridization. We also determined the gene organization of NB-3 in mice and identified the promoter region. In a cross-sectional study, behavior is analyzed under the assumption that life history and experience are similar irrespective of age. However, learning performances would be affected not only by genetic factors but also by the impact of past life history across the life span by factors such as rearing environment or social interactions within the group.
Further analyses are in process.
It has been reported that humoral factors such as hormones, vitamins and growth factors, influence aging of cells and tissues in individuals. Using cell culture system, we investigated serum factors that stimulate or inhibit cell proliferation and migration, in several animals of different ages. We found some interesting phenomena. One discovery is that rat serum contains a novel growth factor that stimulates DNA synthesis exclusively in immortalized cells and that the serum concentration of this substance increases with aging. This substance drastically increased with early cancer development in the rat liver caused by ingesting a carcinogen.