Differential expression of the circadian clock in maternal and embryonic tissues of mice.

Background: Molecular feedback loops involving transcription and translation and several key genes are at the core of circadian regulatory cycles affecting cellular pathways and metabolism. These cycles are active in most adult animal cells but little is known about their expression or influence during development.

Methodology/principal Findings: To determine if circadian cycles are active during mammalian development we measured the expression of key circadian genes during embryogenesis in mice using quantitative real-time RT-PCR.

Developmental events and shoot apical meristem gene expression patterns during shoot development in Arabidopsis thaliana.

Critical developmental and gene expression profiles were charted during the formation of shoots from root explants in Arabidopsis tissue culture. Shoot organogenesis is a two-step process involving pre-incubation on an auxin-rich callus induction medium (CIM) during which time root explants acquire competence to form shoots during subsequent incubation on a cytokinin-rich shoot induction medium (SIM). At a histological level, the organization of shoot apical meristems (SAMs) appears to occur during incubation on SIM about the time of shoot commitment, i.