The Relationship between the Kinetics of Ribonucleic Acid Accumulation and the Morphological Development of the Fern Gametophyte, Dryopteris borreri

Abstract

Fern gametophytes were grown under blue light with and without the addition of 5-fluorouracil or 8-azaguanine, and under red light. Nucleic acids were extracted by either the detergent-chloroform or the detergent-diethylpyrocarbonate method and analyzed by polyacrylamide gel electrophoresis. No significant differences in the relative distribution of the stable RNA components accompanied the transition to biplanar growth. The RNA content per average cell decreased with growth and also varied between the cultural conditions, yet it was independent of the pattern of morphological development. The falling RNA content per average cell resulted from a progressive reduction of the RNA content of the apical cell, as determined histochemically. Since filamentous growth occurred by division of this apical cell, the rate of cell division was independent of the RNA content of the dividing cell.The fern gametophyte can be used to study the RNA (8), since the chloroplasts of Dryopteris filix-mas were larger under blue than under red light (2). The distribution of RNA in various subcellular fractions was examined in Pteridiwn aquilinum grown under red and blue light, and higher RNA contents were observed under blue light for the chloroplast-rich fraction, and also for the nuclei-rich, the mitochondria-rich, and the supernatant fractions (23,24).In the present study the amount of each of the major stable RNA components was determined during growth and transition of Dryopteris borreri by extraction of the RNA and fractionation by polyacrylamide gel electrophoresis. Tissue was grown under red or blue light in order to compare the RNA extracted from continuous filamentous growth with that prepared from gametophytes undergoing transition to biplanar growth. In addition, tissue was grown under blue light in the presence of 5-fluorouracil and 8-azaguanine. Although these RNA base analogues neither prevented transition nor selectively inhibited the biplanar growth rate (5, 18, 26), these two experimental conditions permitted a more critical assessment of the relationship between RNA and the developmental morphology. In the presence of 5-fluorouracil, the filamentous growth rate was inhibited while the mean cell number at the time of transition was unaffected, so that the actual time of transition was retarded (5). Any RNA changes peculiar to transition should therefore occur later in the presence of 5-fluorouracil than in the blue light control. 8-Azaguanine allowed three cell divisions to occur before completely inhibiting further cell production and thereby preventing transition (5). MATERIALS AND METHODS

Ribonucleic Acid Synthesis Associated with a Developmental Change in the Gametophyte of Pteridium aquilinum

“…After 4 days in red light, the radioactive pattern was similar to that observed prior to the shift. (3,10,25,27,28).…”

Changes in Amounts of Chloroplast and Cytoplasmic Ribosomal‐RNAs and Photomorphogenesis in Dryopteris Gametophytes

“…mode and time course of photomorphogenesis) and biochemical differences {i.e. extractability of rRNA) between D. borreri and D. filixmas which these workers have themselves reported Ingle 1970, Ingle andBurns 1968). Since a change in the total-RNA base composition has been shown for D. erythrosora (Table 1 and Hotta 1960); and since a decrease in nucleolar size (Bergfeld 1967) and an increase in chloroplast size (Bergfeld 1963) have been shown to accompany the transition from filamentous to prothallial growth in D. filix-mas, it would be interesting to have such data from D. borreri.…”

“…This is consistent with the observation that chloramphenicol, presumed to have its primary effect on protein synthesis in the chloroplasts, did not prevent this photomorphogenetic transition (Bergfeld 1968). Burns and Ingle (1970) have recently reported that there is no change in the relative amount of chloroplast and cytoplasmic rRNAs during photomorphogenesis in unsterilized cultures of Dryopteris borreri. In addition these workers found that the chloroplast rRNA level did Table 3.…”

Photocontrol of the Orientation of Cell Division in Adiantum. Iii. Effects of Metabolic Inhibitors

“…However, little attention was paid to this point in previous works (SCHRAUDOLI MILLER, 1968;BURNS andINGLE, 1968, 1970;DAVIS, 1968DAVIS, , 1970SCHRAUDOLF and LEGLER, 1969;HOWLAND, 1972). On the contrary, the influences of the inhibitors o n the orientation of the cell plate were successfully examined for the first time under a microscope using an appropriate experimental system.…”

“…BEKCFELD (1964) also pointed out that much of the blue-light-induced protein synthesis resulted from chloroplast development. Lately, evidence has accumulated against the hypothesis (SOBOTA andPARTANW, 1966, 1967;SCHRAUDOLF, 1967;MILLER, 1968;DAVIS, 1968DAVIS, , 1970BURNS andINGLE, 1968,1970;SCHRAUDOLF and LEGLER, 1969;HOWLAND, 1972).…”