Die Photomodulation der Akkumulationsrate von Ascorbinsäure beim Senfkeimling (Sinapis alba L.) durch Phytochrom

Summary Ascorbic acid accumulation in the mustard seedling is controlled by P _fr(active phytochrome). Kinetic studies demonstrate that P _frexerts a rapid and fully reversible control over the steady state rate of ascorbic acid accumulation. Following the terminology of Weisz (1967) for this type of metabolic control the term photomodulation by P _fr is used.—The control by P _fris independent of RNA synthesis. Therefore regulation of gene activity is probably not involved in photomodulation of the rate of ascorbic acid accumulation.—There is only a limited period within which P _frcan control ascorbic acid accumulation. This period is fixed by the time pattern of primary differentiation in the seedling. There is no interaction between photomodulation by P _frand control by primary differentiation of ascorbic acid accumulation.     

Der Einfluss von Phytochrom auf die Stationären Konzentrationen von Ascorbinsäure und Dehydroascorbinsäure beim Senfkeimling (Sinapis alba L.)

Zusammenfassung Der Senfkeimling (Sinapis alba L.) synthetisiert auch im Dunkeln beträchtliche Mengen an Ascorbinsäure. Durch Licht kann der Ascorbinsäure-Gehalt der Keimlinge stark erhöht werden. Dieser Lichteinfluß ist auf die Funktion von Phytochrom zurückzuführen. Die Photosynthese hat keinen wesentlichen Anteil an der Lichtwirkung. Die Konzentration an Dehydroascorbinsäure ist im Verhältnis zur Ascorbinsäurekonzentration stets sehr gering (5–8% der Konzentration an Totalascorbat) und wird vom Phytochrom nicht beeinflußt.Wenn die Funktion von Phytochrom bei den positiven Photomorphosen unter dem Aspekt der differentiellen Genaktivierung (vgl. Mohr, 1966) betrachtet wird, kann die folgende Arbeitshypothese aufgestellt werden: Die durch Phytochrom 730 induzierte Ascorbinsäureakkumulation führt im Bereich von potentiell aktiven Genen zu einer Spaltung gewisser DNS-Histon-Komplexe. Dadurch wird die Synthese von m-RNS an diesen Genen ermöglicht, was schließlich zur Ausbildung der positiven Photomorphosen führt. Die Argumente, welche zur Zeit für eine Funktion der Ascorbinsäure bei der Regulation der Genaktivität sprechen, werden kurz diskutiert.

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The control by phytochrome of the contents of ascorbic acid and dehydroascorbic acid in the mustard seedling (Sinapis alba L.)

Summary A dark grown seedling of white seeded mustard (Sinapis alba L.) contains an appreciable amount of ascorbic acid. The content of ascorbic acid, however, will strongly increase under the influence of light. This effect is due to phytochrome. Photosynthesis is not involved under our experimental conditions.The content of dehydroascorbic acid is always very low compared to ascorbic acid (5–8% of total ascorbate). Phytochrome does not influence this relation.The lag-phase of the phytochrome induced increase in ascorbic acid accumulation is remarkably short, about 1 hour after the onset of light compared to about 4 hours for phytochrome induced anthocyanin synthesis under our conditions.This is the shortest lag-phase we have observed hitherto in the case of positive photoresponses (Mohr, 1966).If we assume that the function of phytochrome in the case of positive photoresponses involves a differential gene activation of potentially active genes (Mohr, 1966) the following working hypothesis can be advanced: phytochrome induced accumulation of ascorbic acid will lead to a separation of DNA-histone complexes in the range of potentially active genes. This makes possible the DNA-dependent synthesis of m-RNAs at those sites which are lastly responsible for the initiation of positive photoresponses. — Arguments are briefly considered which support the view that ascorbic acid exerts a function in connection with the regulation of gene activity.

     

Vom Einfluß des Phytochroms auf die Xylemdifferenzierung im Hypokotyl des Senfkeimlings (Sinapis alba L.)

Zusammenfassung P₇₃₀, das aktive Phytochrom, bewirkt eine vermehrte Bildung von Gefäßen (Tracheen und Tracheiden) im Hypokotyl des Senfkeimlings. Das Differenzierungsmuster der Leitbündel und der Verlauf der Leitbahnen sind im belichteten und im etiolierten Keimling gleich. Es wird geschlossen, daß auch bezüglich der Ausbildung der Leitbahnen das P₇₃₀ lediglich im Rahmen einer sekundären Differenzierung als Auslöser wirkt. Die primäre Differenzierung (vgl. Wagner und Mohr, 1966 b) wird durch P₇₃₀ offenbar nicht beeinflußt.

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Phytochrome-mediated control of xylem differentiation in the hypocotyl of the mustard seedling (Sinapis alba L.)

Summary P₇₃₀, the active phytochrome, causes an increased formation of xylem elements (tracheids and vessel elements) in the hypocotyl of the mustard seedling (Figs. 3,4). On the other hand, the pattern of differentiation of the bundles and the course of the bundles within the hypocotyl (Figs. 1,2) are the same in etiolated as well as in illuminated seedlings.—It has been concluded that in connection with bundle differentiation P₇₃₀ acts only as a trigger at the level of secondary differentiation. The pattern of differentiation is laid down in the course of primary differentiation which apparently is not influenced by P₇₃₀. The same problem has been dealt with more in detail in a foregoing paper (Wagner and Mohr, 1966b).

     

Weitere Untersuchungen zur phytochrominduzierten Akkumulation von Ascorbinsäure beim Senfkeimling (Sinapis alba L.)

Summary The accumulation of ascorbic acid (AS) in the young mustard seedling is greatly increased by the action of the active form of phytochrome (P₇₃₀) (see Schopfer, 1966). There is no photosynthesis in continuous far-red light, which was used throughout the experiments. The phytochrome-mediated increase in AS approximately parallels the synthesis of anthocyanin in the seedling, although the onset of AS-accumulation precedes the anthocyanin synthesis by 2–3 hours (Fig. 4 and 5).—The action of P₇₃₀ increases the amount of AS in every part of the seedling (cotyledons, hypocotyl, radicula) (Fig. 1–3). This increase in AS parallels the formation of P₇₃₀ rather than the different growth responses of these organs (enlargement of the cotyledons, inhibition of hypocotyl and radicula lengthening). The lag in AS-accumulation after onset of far-red irradiation is the same in all 3 parts of the seedling (about 1 hour under the experimental conditions; Fig. 4).—Actinomycin D (10 g/ml), which strongly inhibits anthocyanin synthesis (Fig. 9 and 10), has no corresponding effect on P₇₃₀-dependent increase in AS-accumulation (Fig. 7 and 8). This result support the hypothesis that already active genes are only slightly influenced by actinomycin D (see Lange and Mohr, 1965). It also shows that, in contrast to its role in anthocyanin synthesis, P₇₃₀ probably does not act by initiating potentially active genes in the case of AS-accumulation. — A dark synthesis of anthocyanin in the cotyledons can be obtained by application of AS to the seedlings (Fig. 11). Glucose and sucrose are ineffective in this respect (Table 2). The effect of AS-feeding on anthocyanin synthesis can be inhibited by actinomycin D in very much the same way as light induced anthocyanin synthesis is inhibited (Table 3). — Also the RNA content of the cotyledons is increased by feeding AS in the dark (Table 4).These results are in line with the earlier suggested hypothesis (see Schopfer, 1966) that increase in AS-accumulation is a very early event in the mediation of some positive photoresponses, e.g. anthocyanin synthesis. According to the hypothesis of Mohr (1966 a, b) it has been concluded that AS functions as a part of the signal chain of phytochrome-mediated photomorphogenesis. This signal chain is thought to start differential gene activation to bring about positive photoresponses.     

Die Wirkung von „Störlicht” auf die Blütenbildung von Sinapis alba L.

Summary The induction of flowering in mustard (Sinapis alba L.) was studied by means of night-breaks (Störlicht). The plants were cultivated under fully controlled conditions: 8000 Lux white light (mixed fluorescent and incandescent) 18°C, 80% relative humidity. Raised under our conditions in short days (8 hours of white light) mustard behaved as a quantitative long-day plant (Fig. 2). Flowering can be promoted by long-day treatment (Fig. 3). The long day (16 hours of white light) can be replaced by a short day plus a night-break. The highest effectiveness of the night-break is found near the middle of the dark period (Figs. 4, 5). —The spectral dependence of flower induction was studied with blue, green, yellow, red (Fig. 1) and far-red light using a 2-hour break near the middle of the dark period. The dose response curves (Fig. 6) and the action spectrum (Fig. 7) indicate a very strong effectiveness in the blue part of the spectrum, a small response in red and yellow light and no response at all in green and far-red light. The participation of phytochrome is indicated (Table 1), but no far-red reversibility could be detected (Table 2). Simultaneous irradiation with red and far-red light yielded significant enhancement effects (Fig. 8). In view of the strong shadowing in the leaves (Figs. 9, 10) these data are interpretable on the basis of phytochrome.     

Der Einfluss von Pyrazon auf die Respiration von Senf-(Sinapis alba L.) und Zuckerrübenpflanzen

Rostliny ho??ice bílé a cukrovky byly post?ikány ve fázi prvého páru pravých list? herbicidem pyrazonem (= 1-fenyl-4-amino-5-chlorpyridazonem-6) ve formě suspenzního p?ípravku Pyraminu v 0,4% koncentraci. Za 1 den, za 4, 7 a 14 dní po post?iku byla stanovována respirace v nadzemních ?ástech rostlin na Warburgově respirometru. Metabolický kvocient (vyjád?ený v μl kyslíku spot?ebovaného na 1 mg su?iny za 1 hodinu) byl u ho??ice bílé, která je citlivá v??i pyrazonu, sní?en ve srovnání s rostlinami kontrolními. Potla?ení respirace bylo tím vět?í, ?ím del?í doba uplynula mezi post?ikem a stanovováním respirace. U cukrovky, která je odolná v??i ú?ink?m pyrazonu, byla respirace potla?ena jen za 1 den po post?iku, kde?to v dal?ích termínech zji?t'ování byla respirace potla?ena jen nepatrně. P?i pou?ití mírně subletální dávky herbicidu byl metabolický kvocient cukrovky za 7 dní a 14 dní po post?iku dokonce vy??í ne? v kontrolních rostlinách. Tyto rozdíly v?ak nebyly pr?kazné.     

Die Wirkung von Kinetin, 2,4-DNP und Antimetaboliten auf die Veränderungen im Aminosäurengehalt welkender Pflanzenblätter

Summary It has been established that in intact plants suffering from scarcity of water as well as in isolated withering leaves the amount of proline increases considerably. The main factor in the isolated leaves is thus the scarcity of water and not the injury due to the defoliation. The proline content of the leaves withering in the dark increases only for a few days and then decreases with the diminution of the carbohydrates. Of the active substances tested only 2,4-DNP inhibited the proline synthesis during the withering. It is very probable that in the course of withering the great amount of proline forms during the oxidation of carbohydrates via -ketoglutarate. The oxydative phosphorylation is uncoupled by 2,4-DNP. Kinetin, 2,4-D and antimetabolites applied do not inhibit the abnormal increase of proline.     

Die Hemmung der Phytochrominduzierten Photomorphogenese („Positive” Photomorphosen) des Senfkeimlings (Sinapis alba L.) Durch Actinomycin D und Puromycin

Zusammenfassung Die positiven Photomorphosen Öffnung des Hypokotylhakens und Entfaltung der Kotyledonen können ganz ähnlich wie die phytochrominduzierte Anthocyansynthese und andere positive Photomorphosen durch Actinomycin D und Puromycin gehemmt werden. Man kann daraus schließen, daß diese beiden photomorphogenetischen Reaktionen des Senfkeimlings ebenfalls durch eine von P₇₃₀ über eine Signalkette ausgelöste Aktivierung von potentiell aktiven Genen veranlaßt werden.

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The inhibition of phytochrome-mediated photomorphogenesis (positive photoresponses) by actinomycin D and puromycin in the mustard seedling (Sinapis alba L.)

Summary The many photochrome-mediated photoresponses of a seedling (Sinapis alba L., white seeded mustard) can be divided into 3 categories: positive, negative, and complex photoresponses. Positive photoresponses are those which are characterized by an initiation or a promotion of biosynthetic or growth processes (Mohr, 1966b). Phytochrome-mediated anthocyanin synthesis is the prototype of a positive photoresponse. It has been shown in previous papers (e.g. Lange and Mohr, 1965; Mohr et al., 1965) that positive photoresponses can be specifically inhibited by actinomycin D and puromycin. It has been concluded that in the case of positive photoresponses P₇₃₀ (the active phytochrome) exerts its function through differential gene activation.—In the present paper it has been demonstrated that phytochrome-mediated positive photoresponses of the mustard seedling like opening of the hypocotylar hook and unfolding of the cotyledons can be inhibited by relatively low doses of actinomycin D and puromycin in very much the same way as anthocyanin synthesis or cotyledon enlargement is inhibited. It has been concluded that in these cases too the action of P₇₃₀ must be attributed to an activation of potentially active genes in the manner postulated on the basis of the data on anthocyanin synthesis.

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Die Arbeit wurde durch Sachbeihilfen der Deutschen Forschungsgemeinschaft und der Stiftung Volkswagenwerk (an Prof. Mohr) ermöglicht.     

Die Wirkung der äusseren Bedingungen auf die Veränderung des Geschlechts und auf die Entwicklung von Daphnia pulex de Geer

Ohne Zusammenfassung     

Aktivitätsänderungen der Isocitritase (E C 4. 1. 3. 1.) Während der Photomorphogenese beim Senfkeimling (Sinapis alba L.)

Zusammenfassung In einer vorangegangenen Arbeit (Hock, Kühnert und Mohr, 1965) haben wir festgestellt, daß der Fettabbau im Senfkeimling über das aktive Phytochrom (= P₇₃₀) in einem bestimmten Ausmaß reguliert werden kann. Die Annahme lag nahe, daß die Regulation über die Isocitritase erfolge.In der vorliegenden Arbeit haben wir festgestellt, daß P₇₃₀ keinen Einfluß auf die Isocitritase-Aktivität des Senfkeimlings ausübt, obgleich sich die Isocitritase-Aktivität in dem von uns untersuchten Zeitraum (24–96 Std nach der Aussaat) stark verändert. Um diesen Nachweis zu führen, war es notwendig, störende phenolische Substanzen im Rohextrakt an Divergan zu adsorbieren und die Enzymaktivität auf die biologische Einheit Keimling zu beziehen.Puromycin hemmt die Isocitritase-Synthese stark; Actinomycin D hingegen hat kaum einen Einfluß. — Vielleicht liegt eine langlebige mRNS vor, und die Regulation erfolgt auf der Ebene der Translation. Auch andere Interpretationen sind jedoch möglich.

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Changes of activity of isocitritase (E C 4. 1. 3. 1.) during photomorphogenesis in mustard seedlings (Sinapis alba L.)

Summary In a previous paper (Hock, Kühnert and Mohr, 1965) we have shown that fat degradation in the cotyledons of the mustard seedling (Sinapis alba L). is under the control of active phytochrome (=P₇₃₀), at least to a certain extent. One could imagine that P₇₃₀ might exert this control over fat consumption through isocitritase (E C 4. 1. 3. 1). In the present paper we demonstrate that P₇₃₀ does not have any influence on the activity of isocitritase in the mustard seedling, although the enzyme activity does show a strong increase and a following decline during the time of our experimentation (Fig. 8, 9). — Isocitritase could be assayed in a satisfactory manner in the raw extract only after the adsorption of phenolic compounds on Divergan (Fig. 1, 3). Furthermore the biological unit of the seedling turned out to be the only reliable system of reference for the enzyme activity determined in the extract. Puromycin strongly inhibits isocitritase synthesis whereas Actinomycin D is hardly effective (Fig. 10). It has been concluded that there might exist a relatively stable m-RNA which has been formed during the early stage of germination. Regulation of enzyme synthesis might occur on the level of translation. The evidence for this conclusion is not convincing, however; other interpretations are not excluded.

     

Die Regulation der PAL-Aktivität durch Phytochrom in Senfkeimlingen (Sinapis alba L.)

Summary The present paper is a contribution to the molecular analysis of photomorphogenesis. L-phenylalanine ammonia-lyase (=PAL) (EC 4.3.1.5) has been used as a model system to demonstrate that enzyme synthesis, enzyme inactivation and gene repression are important in determining the response of a particular enzyme to phytochrome.The level of PAL in the mustard seedling is controlled by P_fr (the active form of phytochrome) in a characteristic manner which is illustrated in Fig. 1. The seedlings were irradiated with continuous standard far-red light. Long time irradiation with far-red will maintain a low but virtually constant level of the effector molecule P_fr in the seedling over an extended period of time. At the moment when the far-red light is turned off the action of P_fr will instantly decrease and will eventually cease probably within the order of an hour (cf. Karow and Mohr, 1969). The approach followed in the present paper has been to turn off the far-red light after varying periods and follow the enzyme kinetics in darkness (Fig. 2). The main results can be summarized as follows: The far-red kinetics of PAL (Fig. 1) can be explained as the result of three processes, namely, Pfr-mediated enzyme synthesis, inactivation of PAL by an inactivator, and eventual repression of enzyme synthesis.—During the period 1.5–12 hrs after the onset of far-red only enzyme synthesis occurs. Then enzyme inactivation comes into play while enzyme synthesis continues at a constant rate (Fig. 3). This antagonism of synthesis and inactivation leads to a true steady state which is observed between about 24 and 27 hrs after the onset of far-red. After this period the rate of enzyme synthesis decreases and as a consequence, inactivation dominates. 36 hours after the onset of far-red the P_fr-mediated PAL synthesis is hardly dtectable. The results of secondary irradiations with far-red (Fig.4) indicate that the inactivator of PAL does not have any direct influence on PAL synthesis. The kinetics in darkness (Fig.1,2) can best be understood by assuming that a certain enzyme level represented by the plateau cannot be overcome in the dark. The overshoot response which is obvious in the enzyme kinetics immediately after the cessation of far-red (Fig. 2) cannot be explained readily in molecular terms.

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PAL=Phenylalaninammoniumlyase (EC 4.3.1.5).

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Diese Arbeit ist Herrn Professor H. Borris, Greifswald, mit guten Wünschen zum 60. Geburtstag gewidmet.     

Die Wirkung des Mondes auf die Gewächse

Ohne Zusammenfassung     

Die Wirkung von Sulfhydrilkörpern auf die Histaminase des Mäusedarms

Zusammenfassung 1. Strahlenschutzstoffe der Sulfhydrilreihe und einzelne biogene Amine, insbesondere das Histamin, werden auf die Möglichkeit des Zusammenhanges ihrer Wirkungsweise hin untersucht.2. Es wird am Gewebe des Mäusedünndarms festgestellt, daß die freie SH-Gruppe eine Hemmung der verschiedenen Fermentkomplexe hervorruft, welche das in den Geweben freigesetzte Histamin oxydieren oder substitutiv verändern. Diese Beobachtung wird sowohl in vitro an Darmhomogenat als auch in vivo nach intraperitonealer Injektion des jeweiligen strahlenschutzwirksamen SH-Körpers gemacht.3. Die Hemmung ist in beiden Fällen von der Konzentration des verwendeten SH-Schutzstoffes abhängig.4. Disulfide, die als Strahlenschutzstoffe keine oder eine nur sehr geringe Wirkung haben, zeigen diese Hemmung weder in vitro noch nach Injektion am lebenden Tier. Die Hemmung der Aktivität der Fermente, welche das im Gewebe gebildete Histamin abbauen oder verändern, ist daher in diesem Falle vom Vorhandensein der freien SH-Gruppe abhängig.5. Auf Grund dieser Ergebnisse wird vermutet, daß die durch diese Vorgänge erzeugte lokale Häufung des Histamins im Gewebe möglicherweise eine zusätzliche Schutzwirkung hervorruft, die auf der bereits bekannten, pharmakologisch bedingten Schutzwirkung des Histamins beruht.

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The effect of sulfhydril compounds on the histaminase of the mouse intestine

Sulfhydril compounds and biogenic amines could have a similar mode of action as radioprotectors. In order to check on this possibility, the influence of several sulfhydril compounds on histaminase has been examined. Small known amounts of histamine were added to tissue homogenates in 0.1 M phosphate buffer pH 7.2 and fermentation at 37° C was interrupted after 60 minutes with perchloric acid. The estimation of remaining histamine was carried out fluorometrically by combining with o-Phthalaldehyde after extraction with butanol (modification ofShore's method). In mouse ileum and jejunum it was found that the enzymes oxydizing and substituting histamine were blocked by the free SH-group. With AET, cysteamine and cysteine this effect was shown in homogenates in vitro as well as in the same tissue of animals in vivo after intraperitoneal injection of suitable concentrations of the compounds mentioned above. The effect depended on the concentration of the substances varying between 10^–3 and 10^–4 M. Compounds with their sulfhydril group oxydized to the disulfide, e. g. cystine and cystamine, did not inhibit the enzymes in vitro and in vivo. This inhibition of enzymes which normally destroy histamine in the tissue by oxydation or substitution leads probably to an accumulation of histamine. It is assumed that this accumulation contributes to the prophylactic effect to the sulfhydril compounds against irradiation, since histamine lowers the oxygen tension in the tissues and acts as a good radio-protector. The effect mentioned in this work would reveal a common feature in the mode of action as radio-protectors both of sulfhydril compounds and biogenic amines.

     

Die Wirkung von d-Aminosäuren auf die Struktur und Biosynthese des Peptidoglycans

Zusammenfassung In einem Konzentrationsbereich von 0,02–0,2 M hemmt d-Serin das Wachstum aller untersuchten Bakterien. Gleichzeitig traten morphologische Veränderungen der Bakterienzellen auf. In den nucleotidaktivierten Vorstufen von gehemmten Zellen wurden die d-Alaninreste des Peptidanteils ganz oder teilweise durch d-Serin ersetzt. Auch das Peptidoglycan enthielt d-Serin anstelle von d-Alanin, jedoch weiniger als in den Vorstufen. Zusätzlich war das modifizierte Peptidoglycan zu einem geringeren Anteil quervernetzt als das normale. Vier weitere d-Aminosäuren (Threonin, Valin, Leucin, Methionin) verursachten bei einer Konzentration von 0.2 M ähnliche Wirkungen wie d-Serin. Die Wirkungsweise von d-Aminosäuren auf die Peptidoglycansynthese kann daher allgemein wie folgt beschreiben werden: In Gegenwart von wachstumshemmenden Konzentrationen an d-Aminosäuren werden modifizierte nucleotidaktivierte Peptidoglycanvorstufen synthetisiert, die zu einem geringeren Ausmaß in das Peptidoglycan eingebaut und im Peptidoglycan schlechter quervernetzt werden. Der Ersatz von d-Alanin in Position 4 der Peptiduntereinheit ist dabei in der Regel am wirkungsvollsten. Nur bei Corynebacterium insidiosum und Staphylococcus aureus erwies sich der Ersatz in Position 5 als stärker hemmend. Diese Wirkungsweise entspricht weitgehend derjenigen von Glycin. Im Unterschied zur Wirkung von Glycin kann l-Alanin in Position 1 der Peptiduntereinheit nicht durch d-Aminosäuren ersetzt werden.

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Mode of action of d-amino acids on the biosynthesis of peptidoglycan

The mechanism of growth inhibition by d-amino acids was studied. d-Serine at concentrations from 0.02–0.2 M was sufficient to cause partial growth inhibition in seven species of bacteria representing the four most common types of peptidoglycan. The inhibited cells displayed morphological alterations. In the nucleotide-activated peptidoglycan precursors of these cells, d-alanine residues in position 4 and/or 5 of the peptide moiety were partially or even completely replaced by d-serine. The peptidoglycan also contained d-serine instead of d-alanine, but the percentual content of d-serine was significantly lower than that in the precursors. In addition, the modified peptidoglycan was less cross-linked than the normal one. Four other d-amino acids (d-threonine, d-valine, d-leucine, d-methionine) at concentrations of about 0.2 M caused similar effects as did d-serine when applied to Corynebacterium callunae and Bacillus subtilis. Thus the mode of action of d-amino acids on peptidoglycan synthesis can be generally described as follows: in their presence, at growth inhibiting concentrations modified nucleotide-activated peptidoglycan precursors are formed in which d-alanine residues are replaced by the d-amino acids. They are less efficiently incorporated into peptidoglycan. A high percentage of the modified muropeptides remains non-cross-linked, since they are poor substrates for the transpeptidation reaction. In the majority of the organisms, cross-linking was decreased when d-alanine in position 4 of the peptide subunit was replaced, in two organisms (Corynebacterium insidiosum and Staphylococcus aureus) replacement in position 5 was most effective, however. The low extent of crosslinkage is consistent with the morphological aberrations of inhibited cells. In previous studies with glycine, results were described that were in close analogy to those obtained with d-amino acids. However, glycine can replace not only d-alanine residues in position 4 and 5 but also l-alanine in position 1 of the peptide subunit.

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Verwendete Abkürzungen Dab Diaminobuttersäure - m-Dmp meso-Diaminopimelinsäure - GlcNAc oder G N-Acetylglucosamin - MurNAc oder M N-Acetylmuraminsäure     

Die Wirkung negativer Luftionisation auf die Länge des Oestruszyklus bei Ratten

Zusammenfassung Bei 20 ausgewachsenen weiblichen Ratten mit verlängertem und unregelmässigem Oestruszyklus (13 ± 10 Tage) wurde nach 25 Tagen einer täglichen einstündigen Behandlung mit negativen Luftionen die Zykluslänge auf 6 ± 3 Tage reduziert.

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The irregular and prolonged oestrus cycle of 13 ± 10 days in 20 adult female rats was reduced to 6 ± 3 days after an 1-hr daily treatment with small negative ions for a period of 25 days.

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Resume 20 femelles de rats dont le cycle menstruel était irrégulier et prolongé (13 ± 10 jours) ont été exposées durant 25 jours à de l'air enrichi de petits ions négatifs et cela à raison de 1 heure par jour. Leur cycle en a été réduit à 6 ± 3 jours.

     

Protein- und RNS-Gehalt des Hypokotyls beim stationären Wachstum im Dunkeln und unter dem Einfluß von Phytochrom (Keimlinge von Sinapis alba L.)

Zusammenfassung Das Wachstum des Hypokotyls wurde an Restkeimlingen ohne Kotyledonen (Abb. 1) untersucht. Die Wachstumsgeschwindigkeit ist in dem von uns untersuchten Zeitraum sowohl im Dunkeln als auch unter dem Einfluß von P₇₃₀ (Dauer-Dunkelrot) praktisch konstant. Obgleich sich die Wachstumsgeschwindigkeiten im Dunkeln und im Dauer-Dunkelrot um den Faktor 4 unterscheiden, hat das Dunkelrot keinen signifikanten Einfluß auf den Gesamt-Proteingehalt des Hypokotyls (bzw. der durchschnittlichen Hypokotylzelle). Der Proteingehalt nimmt im Dunkeln und im Licht kontinuierlich ab. Auch der Gesamt-RNS-Gehalt zeigt innerhalb des Versuchszeitraums eine Abnahme, die unter dem Einfluß von Dunkelrot früher einsetzt als im Dunkeln. — Man kann aus den Daten der vorliegenden Arbeit schließen, daß nur ein kleiner Teil des Gesamt-Proteins und der Gesamt-RNS einer Zelle mit dem Zellwachstum unmittelbar in Verbindung gebracht werden kann.

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Protein and RNA contents of the hypocotyl during steady state growth lengthening in the dark and under the influence of phytochrome (seedlings of sinapis alba L.)

Summary Inhibition of hypocotyl lengthening by phytochrome can be regarded as a prototype of a negative photoresponse. The hypothesis has been advanced (Schopfer, 1967) that negative photoresponses are the consequence of a differential gene repression which is exerted by P₇₃₀, the active phytochrome. This hypothesis is mainly based on experiments with specific inhibitors of RNA- and protein synthesis. —The present paper is part of an experimental program which has been designed to check this hypothesis.—Continuous irradiation with standard far-red has been used to establish a virtually stationary concentration of P₇₃₀ over the whole period of experimentation (36–60 hours after sowing). To correlate more strictly the growth response of the hypocotyl with molecular changes in this organ the axis system without cotyledons has been used (Fig. 1). Even under these conditions the growth rate of the hypocotyl is nearly constant in light (continuous far-red) and dark during the whole period of experimentation (36–60 hours after sowing) (Fig. 2, 3). It is known from earlier experiments that cell division in the hypocotyl are very rare during this period and that there is virtually no increase in the DNA contents of the organ during the period of our experimentation (Weidner, 1967). Obviously the number of cells per hypocotyl is virtually constant between 36 and 60 hours after sowing. Organ (i.e. hypocotyl) lengthening is nearly exclusively due to cellular lengthening.—If we follow the protein contents of the hypocotyl we find (Fig. 4) that the total protein of the organ decreases steadily in spite of the fact that the organ grows at a constant rate. There is no significant difference in protein contents between dark-grown and far-red grown systems although the growth rates differ by a factor of 4 (Fig. 2, 3).—The situation is some-what different with respect to total RNA (Fig. 5). The RNA contents eventually decrease in far-red as well as in dark-grown systems but the decrease is significantly faster in the far-red treated systems than in the dark controls.—It is concluded that only a very small part of the total RNA and total protein of a cell can be related to the control of cellular growth. Changes in bulk RNA and bulk protein obviously do not necessarily reflect changes in the growth rate or growth capacity of an organ or a cell.

     

Jahreszyklische Veränderungen im Peritonealepithel des Froschhodens

Ohne Zusammenfassung