Investigations on transcript sizes, steady state mRNA concentrations and diurnal expression of genes encoding fucoxanthin chlorophyll a/c light harvesting polypeptides in the centric diatom Cyclotella cryptica

The transcript sizes of fcp genes of Cyclotella cryptica, belonging to different fcp gene clusters and encoding different fucoxanthin chlorophyll a/c light harvesting polypeptides (Fcps), were determined. Furthermore, the diurnal expression of the fcp 1/fcp2/fcp3/fcp5 gene cluster and the steady state mRNA concentrations of all gene clusters were investigated in response to light quality and quantity. The mRNAs of the gene cluster consisting of fcp1/fcp2/fcp3/fcp5 are approx. 950 bases in length, whereas those of the fcp4 and the fcp6/fcp7/fcp12 clusters are approx. 1050 (fcp4), 880 (fcp6/fcp7) and 1150 (fcp12) bases in lengths. The transcript levels of the fcp1/fcp2/fcp3/fcp5 gene cluster increased with the onset of light, reached a maximum around noon and dropped in the afternoon. The steady state mRNA concentrations of the fcp1/fcp2/fcp3/fcp5 gene cluster and of the fcp4 gene cluster were higher, when Cyclotella cryptica was grown in low light, while the steady state mRNA concentration of the fcp6/fcp7/fcp12 gene cluster increased under high light growth conditions. The steady state mRNA concentrations of all gene clusters were highest when Cyclotella cryptica was grown in red light, intermediate in green light, and lowest in blue light.