Zur Regulation der RNS-Synthese durch Phytochrom bei der Photomorphogenese des Senfkeimlings (Sinapis alba L.)

Summary P₇₃₀, the active phytochrome, increases the rate of RNA synthesis (Table) and the RNA contents in the cotyledons of the mustard seedling (Sinapis alba L.) (Fig. 1) whereas the RNA contents in the hypocotyl is decreased under the influence of P₇₃₀ (Fig. 2).—It takes about 6 hours until changes in the RNA contents-which must be attributed to the formation of P₇₃₀—can be measured after the onset of light (continuous far-red). Since the lag-phases of positive photoresponses in the cotyledons and negative photoresponses in the hypocotyl (Mohr, 1966) are in general much shorter than 6 hours, the changes of the RNA contents of the organs cannot be regarded as being directly connected with the formation of characteristic positive photoresponses such as anthocyanin synthesis, induced enzyme synthesis, ascorbic acid synthesis, etc., or negative photoresponses such as inhibition of hypocotyl lengthening.We have rather to conclude that the changes of RNA contents are secondary adaptations of the organs which lead to an increase (cotyledons) or decrease (hypocotyl) of protein synthesizing capacity of the cells and tissues. The P₇₃₀-dependent increase of bulk RNA in the cotyledons is probably due to a differential gene activation and the P₇₃₀-dependent decrease of bulk RNA in the hypocotyl is due to a differential gene repression. The causalities of these processes are possibly complex.The hypothesis of differential gene activation or repression by P₇₃₀ (Mohr, 1966; Schopfer, 1967a, b) is not disproved by these results. We have rather to reach a conclusion which has already been suggested by other data (e.g. Karow and Mohr, 1966), namely, that positive as well as negative photoresponses are due to changes in the activity of a limited (possibly small) number of enzymes. Correspondingly changes in only a minute amount of the total RNA are directly involved in the formation of photoresponses. These changes cannot be detected by following RNA contents.—It seems to be of great interest, however, that P₇₃₀ eventually brings about strong tissue specific changes in the RNA contents per cell as described in the present paper.     

Untersuchungen zur Energetik der phytochrominduzierten Photomorphogenese des Senfkeimlings (Sinapis alba L.)

Zusammenfassung Im Zusammenhang mit der Energetik der Photomorphogenese wurden Trockenmasse, Fettgehalt und Verbrennungswärme zu Beginn und Ende des Versuchszeitraums bestimmt und die Kinetik der Sauerstoffaufnahme und Kohlendioxidabgabe aufgenommen. DR-Dauerbestrahlung verschiebt das Maximum der O₂-Aufnahme und CO₂-Abgabe auf einen späteren Zeitpunkt und führt insgesamt zu einer Steigerung des Gasstoffwechsels. Fettabbau und Energieabgabe werden ebenfalls gesteigert, obwohl die Syntheseleistungen des Keimlings (gemessen als fettfreie Trockenmasse bzw. deren Verbrennungswärme) geringer sind als bei den Dunkelkontrollen. Für das Absinken der Ausbeute während der Photomorphogenese werden verschiedene Erklärungsmöglichkeiten angegeben.Eine theoretische Ableitung zeigt, daß der relative Meßfehler bei der indirekten manometrischen Methode gegenüber der direkten Methode mit abnehmendem respiratorischen Quotientem immer größer wird.

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Investigations on the energetics of phytochrome mediated photomorphogenesis in mustard seedlings (Sinapis alba L.)

Summary To characterise the energetics of whole seedlings of Sinapis alba L. during photomorphogenesis under continuous far-red light, measurements were made (between 36 and 72 hours after sowing) of changes in dry weight, fat content, heat of combustion, O₂ uptake and CO₂ evolution in irradiated and dark treated control plants. Irradiation caused a delay in the time of maximum O₂ uptake and CO₂ evolution and led to an increase in the total gaseous metabolism. Likewise, the rates of breakdown of fats and release of energy were increased; this occurred even though the total synthesising capacity of the seedlings, as measured by fat free dry weight or by heat of combustion of fat free dry matter, was lower in the farred irradiated seedlings than in the dark controls. Thus, during the course of photomorphogenesis the yield of plant material, as measured by the increase in fat free dry matter divided by the decrease in fat, or by the increase in heat of combustion of fat free dry matter divided by the decrease in heat of combustion of fat, was markedly reduced (approximately 60%). Several possible explanations were put forward to account for this reduction, but lack of thermodynamic data allowed none to be favoured.Theoretical considerations showed that the experimental error associated with measurements of gaseous metabolism was always larger when the indirect manometric method rather than the direct method was used. This effect was more pronounced the higher the respiratory quotient was.

     

Kinetische studien zur Interpretation der Wirkung von Sukzedanbestrahlungen mit Hellrot und Dunkelrot bei der Photomorphogenese (Anthocyansynthese bei Sinapis alba L.)

Zusammenfassung In einer früheren Arbeit (Bertsch und Mohr, 1965) haben wir bei der lichtinduzierten Anthocyansynthese des Senfkeimlings gefunden, daß eine Vorbestrahlung mit Dunkelrot die Wirkung einer nachfolgenden Bestrahlung mit Hellrot steigert. Eine Vorbestrahlung mit Hellrot hingegen reduziert die Wirksamkeit einer nachfolgenden Bestrahlung mit Dunkelrot (Tabelle 1). Die 48 St nach Beginn des Bestrahlungsprogramms vorhandene Menge an Anthocyan wurde als ein Maß für die Wirksamkeit der Sukzedanbestrahlungen angesehen. — In der vorliegenden Arbeit wurde mit Hilfe kinetischer Studien gezeigt, daß ein spezifischer Effekt der Dunkelrot-Vorbestrahlung nicht existiert. Der apparente Effekt ist darauf zurückzuführen, daß das zuerst gegebene Dunkelrot die lag-Phase für das nachfolgende Hellrot eliminiert. — Der Effekt, daß eine Hellrot-Vorbestrahlung die Wirkung von nachfolgendem Dunkelrot stark reduziert, ist hingegen real. Dieser Effekt muß auf einen Verlust an Phytochrom zurückgeführt werden.

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Kinetical studies to interpret the effects of succedaneous irradiations with red and far-red on photomorphogenesis (anthocyanin synthesis in mustard seedlings, Sinapis alba L.)

Summary In a previous paper (Bertsch and Mohr, 1965) we reported that in light-induced anthocyanin synthesis of the mustard seedling (Sinapis alba L.) a preirradiation with far-red light increases the effectiveness of a following irradiation with red light, whereas a preirradiation with red reduces the effectiveness of a following irradiation with far-red (Table 1). The amount of anthocyanin present 48 hours after the onset of the irradiation programme was taken as a gauge for the effectiveness of the irradiation with succedaneous red and far-red (and vice versa).In the present paper it is shown—using detailed kinetical studies (Fig. 1 and 2) —that a specific potentiating effect of the preceding far-red is not involved. The apparent effect is due to the fact that the preceding far-red eliminates the lag-phase for the following red (Fig. 1). — On the other hand, the depressing effect of red light preceding far-red is very real. This latter effect must be attributed to a loss of phytochrome.We demonstrate in the present paper that the effects of succedaneous red and far-red irradiations can be attributed altogether to phytochrome if several assumptions concerning the stability of phytochrome 730 (Hartmann, 1966; Wagner and Mohr, 1966) are made. These assumptions seem to be well justified. — In any case our kinetical studies have revealed no data which indicate that in red or far-red light we have to deal with anything else except phytochrome.

     

Die Wechselwirkung von Hellrot,Dunkelrot und Blaulicht bei der Photomorphogenese von Farngametophyten [Dryopteris filix-mas (L.) Schott]

Summary In Fig. 1 we have reproduced the action spectrum of photomorphogenesis in fern gametophytes (Dryopteris filix-mas (L.) Schott). The morphogenetic index L/W is shown as a function of wavelength (L=length, W=maximal width of the protonema). In experiments in which simultaneous irradiation with red and far-red was applied it has been shown (Fig. 2) that the effect of red light (lowering of the L/W-index) can be nullified by a simultaneous application of a suitable quantum flux density of far-red light. This fact means that the effects of red and far-red light on morphogenesis as measured by the L/W-index (Fig. 1) can be attributed exclusively to phytochrome.The strong morphogenetic effect of short wavelenth visible (=blue) light (strong lowering of the L/W-index) cannot be influenced by simultaneously applied far-red light (Fig. 4), whereas red light cancels the effect of blue light to a certain extent as measured by the L/W-index (Fig. 5). It has been concluded that the effect of blue light is due to a photoreceptor other than phytochrome, probably a flavoprotein. The antagonism between blue and red can be understood if we assume that the phytochrome-mediated growth at the tip of the apical cell of the protonema (e.g. Etzold, 1965) is fully promoted by P₇₃₀ only at a high relative concentration of P₇₃₀. The low relative concentration of P₇₃₀ under far-red light is too low to counteract significantly the blue light dependent response. Blue light initiates isodiametric growth of the apical cell instead of tip growth (Mohr, 1965). Under far-red light (a low level of P₇₃₀) growth of the apical cell seems to be restricted to the extreme tip of the apical cell. Slender protonemas with a high L/W-index are the result. Under red light (a high level of P₇₃₀) the growing zone of the apical cell is somewhat broader. As a consequence the protonemas are broader and the L/W-index is lowered.     

Die lag-Phase bei der FUDR-Wirkung auf DNA-Synthese und Streckungswachstum bei Sinapis alba

Summary In the seedlings of Sinapis alba, the lag-phase between the application of 5-FUDR and the beginning of the inhibition of elongation growth and the inhibition of DNA-synthesis has been studied. The elongation was retarded after 7 h, and then, depending on the concentration of the FUDR, was completely stopped. In the cotyledons the DNA-synthesis was strongly reduced after about 50 minutes, and in the hypocotyls a lag-phase of less than 30 minutes was observed. With the addition of thymidine the DNA-synthesis was immediately resumed, while the growth began with a lag-phase of 5–7 h. In every case the change in the DNA-synthesis preceded the change in the elongation growth. The inhibition of elongation growth could, therefore, be the consequence of inhibition of DNA-synthesis.     

Die Phenylalaninammoniumlyase (PAL,EC 4.3.1.5) des Senfkeimlings (Sinapis alba L.), ein elektrophoretisch einheitliches Enzym

Summary Improved techniques in localization of phenylalanine ammonia-lyase (PAL) on polyacrylamide disk electrophoresis columns indicate that the enzyme synthesized under the control of phytochrome is electrophoretically indistinguishable from the enzyme present in dark grown mustard seedlings. Furthermore, no heterogeneity of PAL with respect to molecular size has been detected. However, the formation of high molecular weight aggregates with PAL activity in tris buffer of low concentration has been demonstrated. The data lead to the conclusion that phytochrome does not induce the synthesis of a novel PAL enzyme differing in its structural properties from the PAL in dark grown seedlings. The observations of other investigators on separable forms of PAL are critically discussed.     

Der Lichteinfluss auf die Haarbildung am Hypokotyl vonSinapis alba L.

Summary In an earlier paper (Mohr 1957) it was described that the formation of anthocyanin and the inhibition of lengthening of the hypocotyl of dark grown seedlings (Sinapis alba) is governed by the action of two photomorphogenic action systems. The one system is the well known reversible red far-red reaction system (low energy reaction), the other one is a high energy reaction system which can be called — in reference to the action peaks in the far-red and in the blue — blue far-red reaction system. The chemical nature of the absorbing pigments is still unknown.In the present paper another photomorphogenic response of the young dark grown seedlings ofSinapis alba, the light dependent formation of unicellular hairs from epidermal cells of the hypocotyl, has been investigated. It has been shown that this response is also governed by these two reaction systems. These systems have been physiologically separated. Experiments have been presented which evaluate the importance of the assumption that the red absorbing pigment of the reversible red far-red pigment system is reformed from a precursor when the pigment present before irradiation is transformed into the far-red absorbing pigment by an irradiation with red.

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Mit 3 Textabbildungen     

Phytochrome-regulated Expansion of Mustard (Sinapis alba L.) Cotyledons

In developing mustard (Sinapis alba L.) seedlings continuousred light acting via the agency of phytochrome stimulates therate of expansion of cotyledons. Although phytochrome actionon cotyledon expansion is evident only after 36 h from sowing,the photoresponse escapes from reversibility at about 15 h fromsowing. The time lag of 21 h between loss of photoreversibilityand the onset of photoregulated cotyledon expansion indicatesthe existence of long-lived components in the phytochrome-triggeredsignal chain. Phytochrome-regulated cotyledon expansion doesnot require the involvement of photosynthesis, as applicationof SAN 9789, an inhibitor of chloroplast biogenesis, did notaffect cotyledon expansion. The role of turgor pressure-relatedcellular parameters such as osmotic potential () cell wall extensibility(m), hydraulic conductivity (L) and yield threshold (Y) forcell expansion were examined during photoregulated cotyledonexpansion. Using the general equation of cell growth dv/dt =[Lm/(L+m)]( - Y), where dv/dt is the rate of volumetric growth,it was demonstrated that the light-mediated cotyledon expansionresults from an increase in cell wall extensibility (m). Theseresults are discussed in relation to the photoregulation ofcotyledon expansion. Key words: Cell wall extensibility, growth, Sinapis alba L., phytochrome     

Aerobe und anaerobe Glykolyse bei der Entwicklung des Froscheies (Rana temporaria L.)

Zusammenfassung Die Milchsäure wurde unter aeroben und anaeroben Verhältnissen in verschiedenen Stadien der Froschentwicklung bestimmt. Es wird eine anaerobe Glykolyse festgestellt. Die Atmung verdrängt die Milchsäure, denn aerob ist nur eine schwache Glykolyse festzustellen. Der Milchsäuregehalt des unbefruchteten und des befruchteten Eies ist gleich. Die anaerobe Glykolyse steigt im Laufe der Entwicklung. Die Entwicklung kann auch anaerob vor sich gehen, kommt aber schließlich zum Stillstand. Die Neurula sind bedeutend empfindlicher gegen Sauerstoffmangel als die Keime in früheren Stadien der Entwicklung.     

Ausbildungsformen von kutikula und kutikularen kleinorganen bei der honigbiene (Apis mellifica L.)

Zusammenfassung Ausbildungsformen der Kutikula bei Larve, Puppe und Imago werden beschrieben.Die Mächtigkeit der Kutikula ist abhängig von der Anzahl der sie aufbauenden Epidermiszellen.Polyploide Epidermiszellen bilden Verbände haarartiger, fächerartiger und höekerartiger Trichome, die teilweise die Länge der echten Haare übertreffen. Die Grö\Be der Trichombildung ist abhängig vom Polyploidiegrad der Bildungszellen.Borsten und Epithelzellen stehen in gesetzmäßigem Zusammenhang, der auf die Entwicklung aus Borsten-Epithel-Stammzellen zurückgeführt wird. Epidermiszellen können rich zu Nebenzellen differenzieren.Bei Gelenkflächen verhindern Trichome das Gleiten von Skleriten aufeinander. Bewegliche Gelenkmembranen ermöglichen starke Strekkungen. Die Epidermiszellen der Membranen werden in der Imago nicht rückgebildet.Sinnesorgane besitzen unterschiedliche Anzahlen von zugehörigen Epidermiszellen und Sinneszellen Bowie unterschiedliche Kernausstattung der Bildungszellen.Über Hautdrüsen bilden sich Kutikulasonderformen.Die Kastenmerkmale Trichome des Stachelapparates, Höcker des Pollenkneters und Widerhaken der Stechborsten differenzieren sich durch unterschiedlichen Polyploidiegrad der Bildungszellen. Die unterschiedliche Anzahl der Sammeltarsusborsten wird auf den untersehiedlichen Zeitpunkt der ersten differentiellen Teilung zurückgeführt.Bei den Porenplatten der Antennen, den Sinneskuppeln an den Stechborsten und den superfiziellen Postgenaldrüsen entwickelt sich die Arbeiterin wie bei den übrigen Merkmalen über das Stadium hinaus, auf dem die Konigin stehen bleibt. Die Befunde unterbauen die These von Demoll von der atavistischen Natur der Bienenkönigin.