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1

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Biosynthese der ribosomalen RNS bei der blaugrünen Alge Anacystis nidulans (1973)

Seitz, Ursula ; Seitz, Ulrich

Springer

Archives of microbiology 90 (1973), S. 213-222

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ISSN: 1432-072X

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Description / Table of Contents: Zusammenfassung 1. Der Biosyntheseweg der ribosomalen RNS der blaugrünen Alge Anacystis nidulans wurde untersucht. Die beiden rRNS-Komponenten 16S-RNS (Mol.-Gewicht 0,54×106) und 23S-RNS (Mol.-Gewicht 1,02×106) besitzen keine gemeinsame hochmolekulare Vorstufe. Die Synthese der 16S-RNS verläuft über eine Vorstufe (p16S-RNS) mit einem Mol.-Gewicht von 0,66×106. Sie tritt bereits nach 1 min Inkubation mit [3H]-Uridin im Polyacrylamidgel auf. Für die 23S-RNS ist ein solcher Vorläufer mit deutlich höherem Mol.-Gewicht nicht nachzuweisen. 2. Die p 16S-RNS ist nicht methyliert. Nach den bisher zu dieser Frage durchgeführten Experimenten erfolgt die Methylierung erst, wenn die rRNS die Kettenlänge des reifen Moleküls besitzt. 3. Außerdem wurde die Stabilität der rRNS in Abhängigkeit von Mg-Ionen in vivo und in vitro untersucht und diskutiert. In vivo: Im Mg-freien Kulturmedium reduziert sich der rRNS-Gehalt der Zellen relativ zu den übrigen Nucleinsäurekomponenten in Abhängigkeit von der Kulturdauer. Der Nachweis für diesen Effekt wird mit Hilfe von MAK-Chromatographie erbracht. In vitro: Wird Mg2+ im Extraktionspuffer weggelassen, zerfällt ein Teil der 23S-RNS. Die Bruchstücke wandern als getrennte Banden im Polyacrylamidgel. 2 bis 10 mM Mg2+ stabilisieren die 23S-RNS.

Notes: Summary 1. The biosynthetic pathway of rRNA in the blue-green alga Anacystis nidulans is investigated. The molecular weights of mature 16S and 23S RNA are 0.54×106 and 1.02×106 and were determined on the basis of electrophoretic mobility. No high molecular precursor for both RNA components exists in blue-green algae. A p 16 S RNA for which the molecular weight was determined to be 0.66×106 was found even after 1 min incubation with [3H]-uridine. On the contrary, no p23S RNA migrating slower than the 23 S RNA appears in the gel. 2. The p16S RNA is not methylated. A few experiments in this direction show that methylation takes place only after the rRNA attains its final molecular weight. 3. The dependence of rRNA on Mg2+ for stability in vivo and in vitro is studied. MAK chromatography shows that the proportion of rRNA is strongly reduced after Mg-starvation. In vitro: 23S RNA is partly cleaved when homogenization and extraction take place in a buffer system without Mg2+. Mg2+ in a concentration of 2 to 10 mM prevents the cleavage of this RNA during the process of extraction.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00424973

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Selektive Hemmung der Synthese der AMP-reichen RNS durch α-Amanitin in Zellen höherer Pflanzen (1971)

Seitz, Ulrich ; Seitz, Ursula

Springer

Planta 97 (1971), S. 224-229

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ISSN: 1432-2048

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary The effect of α-amanitin on the synthesis of AMP-rich RNA has been investigated. After incubation of freely suspended callus cells of parsley with the toxin and pulse labelling (30 min) with 32P-orthophosphate, the high AMP content of the RNA component eluted from MAK columns behind the 25 S-RNA disappears. The base ratio of this RNA becomes ribosomal (CMP 20.1, AMP 26.5, GMP 28.4, UMP 25.0). Polyacrylamide gel electrophoresis of the high molecular RNA shows that radioactivity is incorporated only into the 32 S-RNA. At higher α-amanitin concentrations the total nucleic acid synthesis is reduced. In this case only the high molecular RNA (32 S-RNA) is produced.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00389203

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3

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Purification and substrate specifities of hydroxycinnamate: CoA ligase from anthocyanin-containing and anthocyanin-free carrot cells (1977)

Heinzmann, Ursula ; Seitz, Ursula ; Seitz, Ulrich

Springer

Planta 135 (1977), S. 313-318

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ISSN: 1432-2048

Keywords: Anthocyanin ; Daucus ; Hydroxycinnamate: CoA ligase ; Tissue culture

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Callus cells of Daucus carota L. have different phenylpropanoid pathways depending on the medium composition. Cells propagated on a medium with gibberellic acid do not accumulate cyanidin but incorporate [14C]phenylalanine into chlorogenic acid at a high rate. Cells grown on a medium free of gibberellic acid accumulate cyanidin in very large amounts. We here describe partial purification of hydroxycinnamate: CoA ligase, and its properties in these two cell lines. The enzymes extracted from the two cell populations had different substrate specifities: for that from anthocyanin-containing cells, p-coumaric acid was the best substrate, and caffeic acid and ferulic acid were also activated. With enzyme from anthocyanin-free cells, the lowest Km values were obtained for caffeic acid, while ferulic acid had higher values, and p-coumaric acid was nearly inactive. The enzyme did not separate into isoenzymes during purification. Only on polyacrylamide gels the partially purified enzyme from anthocyanin-containing cells separated into three peaks, and that from anthocyanin-free cells, into only two peaks. This difference is discussed in the context of the lack of activity with p-coumaric acid in anthocyanin-free cells.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00384906

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4

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Kern-Plasma-Transport neusynthetisierter rRNS in Zellen einer Suspensionskultur von Petroselinum sativum (1972)

Seitz, Ursula ; Seitz, Ulrich

Springer

Planta 106 (1972), S. 141-148

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ISSN: 1432-2048

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary A rapidly labelled rRNA precursor can be detected in callus cells of Petroselinum sativum grown on a liquid synthetic medium. Its molecular weight has been calculated to be 2.3×106. This value agrees with that of the rRNA precursor from other plant material. In order to follow the synthesis and processing of rRNA in time and to correlate single steps in this process with cell organelles it was necessary to obtain pure fractions of nuclei and ribosomes. The isolation method for nuclei is given in detail. The nucleic acids are separated on polyacrylamide gels of low acrylamide concentration. Pulse-chase experiments show that the rRNA precursor is split into two fragments within the nucleus: an 18S and a 25S component. The 18S RNA leaves the nucleus rapidly. It is already found quantitatively in the ribosomal fraction after 30–60 min chase. At that time the 25S RNA is still within the nucleus; it appears much later in the ribosomes. Since the increase in ribosomal label occurs simultaneously with the decrease in nuclear label, it is concluded that there is no degradation of 18S RNA within the nucleus. Apparently there are two distinct transport mechanisms with different kinetics for the two RNA components.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00383993

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5

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Cryopreservation of Digitalis lanata Ehrh. cell cultures: Preculture and freeze tolerance (1991)

Göldner, Eva M. ; Seitz, Ursula ; Reinhard, Ernst

Springer

Plant cell, tissue and organ culture 24 (1991), S. 19-24

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ISSN: 1573-5044

Keywords: cell cultures ; cell viability ; cryopreservation ; Digitalis lanata ; preculture treatments

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Cryopreservation experiments were performed with Digitalis lanata cell cultures. The main stress was laid on the behaviour of the cells during the preculture period and the capacity of various preculture additives to induce freeze tolerance. The following compounds were used as preculture additives: trehalose, mannitol, sucrose, melibiose, proline, and sorbitol. They are listed in the order of their respective efficiency. Using trehalose, high post-thaw viability rates were achieved and the cells resumed growth after a short lag period. Melibiose was used as a preculture additive for the first time. Its suitability was in the range of that of sucrose. Proline and sorbitol were not able to induce freeze tolerance in Digitalis cells. Cell viability showed a considerable decrease at the beginning of the preculture period. This reduction was found to be transient in the presence of trehalose, mannitol, sucrose, and melibiose. The damaging effects of proline and sorbitol were too severe to be compensated for by the cells. The PAL activity increased markedly in the presence of proline, whereas the trehalose-treated and the control cells behaved nearly identical to one another.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00044260

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6

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Transcription and processing of rRNA in higher plant cells (Daucus carota, Petroselinum crispum, Acer pseudoplatanus) (1980)

Seitz, Ursula

Springer

Plant systematics and evolution 134 (1980), S. 11-21

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ISSN: 1615-6110

Keywords: Angiosperms ; Daucus ; Petroselinum ; Acer ; rRNA ; transcription ; precursors of less than 2.5 × 106 daltons ; processing

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Actively dividing cells from parsley (Petroselinum crispum) and carrot (Daucus carota) (bothApiaceae) andAcer pseudoplatanus (Aceraceae) were used to detect the primary gene product of the rDNA in plant cells. Parsley and carrot cells were labelled with [32P] orthophosphate. In both cases only one high molecular weight rRNA precursor was present on polyacrylamide gels under non-denaturing conditions. Its molecular weight did not exceed 2.5 × 106 daltons. The component emerged from the heterogenous material after a labelling period of 5–10 min. In parsley cells 45 min after onset of incubation labelled mature rRNA (25S and 18S) arrived in the cytoplasm. InAcer pseudoplatanus (incubation period 60 min) two rapidly labelled components did emerge from polyacrylamide gels; their molecular weights were 2.3 and 3.2− 3.4 × 106 daltons. After electrophoresis under denaturing conditions the larger component was no longer present, thus indicating that it was an aggregate of different RNA molecules. The molecular weights of the rRNA precursors ofD. carota andP. crispum determined after electrophoresis in formamide gels were about 2.1 × 106 daltons. From these results we have no evidence for the existence of rRNA precursors exceeding the molecular weight of 2.5 × 106 daltons.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00985028

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