Kern- und Nucleolusausbildung in den Gametophytenzellen von Dryopteris filix-mas (L.) Schott bei Umsteuerung der Morphogenese

The young gametophytes of the fern Dryopteris filix-mas (L.) SCHOTT have different metabolic patterns in red and blue light with blue favouring protein formation. In connection with this, the morphogenesis is also different. Two-dimensional prothallia are developed in blue light; in red light, however, the gametophytes grow as filaments. In the present paper the influence of red and blue radiation upon the size of the nuclei and nucleoli has been studied in fully differentiated stable basal cells and actively dividing apical cells. Time course studies revealed that the apical cell of the red form always contains extremly large nuclei and nucleoli. This is in agreement with high synthetic activity of this cell. In contrast, the apical cells with two cutting faces of the blue grown gametophytes have much smaller nuclei and nucleoli (this may be due to the comparativly high dividing activity of this cells). In already differentiated basal cells, these two organelles are even smaller and show only minor differences between red and blue ones. Within the gametophytes there is a gradient in the nucleus and nucleolus size from the apical to the basal cells.

If blue grown gametophytes are brought into red light, or vice versa, typical changes in size of the nucleus and nucleolus in the direction of the respective forms are already visible after 3 hrs. under the new conditions. These changes in size and synthetic activity occur much earlier than any measurable morphological alteration. The data give good evidence for the fact that the striking change in the morphogenesis is preceded by a fundamental change in the synthetic activity of the nucleus and nucleolus.