“…In Chlamydomonas, the level of mRNA encoding PBGS increased about seven-fold upon transfer of synchronously growing cells from dark to light, with a corresponding three-fold increase in PBGS activity (Matters and Beale, 1995ab). By comparison, PBGS, PBGD, and UROS activities have been reported to increase three-to six-fold in etiolated pea leaves during the first 48-60 h of greening (Smith, 1986;Spano and Timko, 1991;Witty et al, 1993). In addition, expression of PBGS, PBGD, and CPOX appears to be regulated to a greater extent by developmental age rather than light, with higher levels of immunodetectable protein and mRNA found early in leaf development in the light or dark compared to later stages when the tissues are completely differentiated (He et al, 1994;Kruse et al, 1995).…”