1,993 publications from this institution
One of the major challenges in molecular genetics is to determine the mechanisms which control the utilization of genetic information in time -and space -dependent manners. Differential gene activation is the basis for the processes of cellular differentiation and specialization. Through genetic analysis, a great deal has been learned about the general mechanisms which control these processes in organisms such as D. melanogaster and C . elegans . Although mammals, on the other hand, are refractory to genetic analysis, significant progress has been made in understanding the mechanisms involved in determining tissue specific gene expression in these organisms. This can be mostly attributed to a biochemical approach employing in vitro transcription systems in which differential promoter utilization could be observed, resulting in identification of transcription factors mediating cell-type specific gene expression (Scheidereit et al. 1987;
Youth are active in multiple locations, but it is unknown whether more physical activity in one location is associated with less in other locations. This cross-sectional study examines whether on days with more physical activity in a given location, relative to their typical activity in that location, youth had less activity in other locations (i.e., within-person associations/compensation). Participants were 528 adolescents, ages 12 to 16 (M = 14.12, SD = 1.44, 50% boys, 70% White non-Hispanic). Accelerometer and Global Positioning System devices were used to measure the proportion of time spent in moderate-to-vigorous physical activity (MVPA) in five locations: home, home neighborhood, school, school neighborhood, and other locations. Mixed-effects regression was used to examine within-person associations of MVPA across locations and moderators of these associations. Two of ten within-participant associations tested indicated small amounts of compensation, and one association indicated generalization across locations. Higher at-school MVPA (relative to the participant’s average) was related to less at-home MVPA and other-location MVPA (Bs = −0.06 min/day). Higher home-neighborhood MVPA (relative to the participant’s average) was related to more at-home MVPA (B = 0.07 min/day). Some models showed that compensation was more likely (or generalization less likely) in boys and non-whites or Hispanic youth. Consistent evidence of compensation across locations was not observed. A small amount of compensation was observed for school physical activity, suggesting that adolescents partially compensated for high amounts of school activity by being less active in other locations. Conversely, home-neighborhood physical activity appeared to carry over into the home, indicating a generalization effect. Overall these findings suggest that increasing physical activity in one location is unlikely to result in meaningful decreases in other locations. Supporting physical activity across multiple locations is critical to increasing overall physical activity in youth.
