Abstract
Nitrogen (N) deprivation of Chlamydomonas reinhardtii cells triggers not only an adaptation program to acclimate to N starvation, but also a gamete program which permits them to mate to form zygotes. We searched genes from the Chlamydomonas cDNA macroarrays, whose expression is greatly enhanced under -N conditions, and isolated 19 novel genes, named Nsg (N-starved gametogenesis). In this study we analyzed their expression patterns during synchronized gametogenesis.
Synchronized vegetative cells in the early G1 phase were incubated in -N medium. Gametic differentiation occurred between 2 and 4 h, and over 95% cells became gametes within 5 h incubation. Northern blot analyses showed that Nsg genes are classified into 3 temporal classes; early (1-2 h, 1 gene), middle (3-4 h, 15 genes) and late (6-7 h, 3 genes). Early and late genes appeared to be related to the adaptation program, while middle genes to be related to the gamete program.
