Distributing Plant Developmental Regulatory Proteins via Plasmodesmata

During plant development, mobile proteins, including transcription factors, abundantly serve as messengers between cells to activate transcriptional signaling cascades in distal tissues. These proteins travel from cell to cell via nanoscopic tunnels in the cell wall known as plasmodesmata. Cellular control over this intercellular movement can occur at two likely interdependent levels. It involves regulation at the level of plasmodesmata density and structure as well as at the level of the cargo proteins that traverse these tunnels. In this review, we cover the dynamics of plasmodesmata formation and structure in a developmental context together with recent insights into the mechanisms that may control these aspects. Furthermore, we explore the processes involved in cargo-specific mechanisms that control the transport of proteins via plasmodesmata. Instead of a one-fits-all mechanism, a pluriform repertoire of mechanisms is encountered that controls the intercellular transport of proteins via plasmodesmata to control plant development.

Early human interaction: mother and child

Studies of the differing means of definition problems of parturition and neonatal dependence, the extent of human variability underlying them, and the possibilities for enrichment of experience in early human interaction call into question such standard practices as isolation of the newborn, separation of mother and infant immediately after birth, and division of the family unit at the very time when it is symbolically and in reality becoming a family unit.