Bacteriochlorophyllgehalt und Proteinmuster der Thylakoide von Rhodospirillum rubrum während der Morphogenese des Photosynthese-Apparates

Zusammenfassung Der Zusammenhang zwischen dem spezifischen Bacteriochlorophyllgehalt der Zellen und der Thylakoidmorphogenese wird an Rhodospirillum rubrum untersucht. Bei der Induktion des Photosynthese-Apparates wird zunächst Bacteriochlorophyll synthetisiert, obgleich noch keine Thylakoide gebildet werden (1. Phase). Werden Thylakoide ausgebildet, so steigt der spezifische Bacteriochlorophyllgehalt der Thylakoide in Abhängigkeit vom spezifischen Bacteriochlorophyllgehalt der Zellen an, bis ein Wert von 12–13 g Bacteriochlorophyll je mg Zellprotein erreicht ist (2. Phase). Während der Wert für die Zellen darüber hinaus weiter erhöht werden kann, bleibt der Wert der Thylakoide konstant bei 100 g Bacteriochlorophyll je mg Thylakoid-Protein (3. Phase). Isolierte Thylakoide aus Zellen mit niedrigem Bacteriochlorophyllgehalt besitzen geringere Durchmesser als Thylakoide aus Zellen mit höheren Werten. Auch hinsichtlich der Zusammensetzung der Thylakoide in Abhängigkeit von den steigenden Bacteriochlorophyllgehalten bei induzierten Zellen konnten Unterschiede festgestellt werden. Ähnlich wie die spezifischen Bacteriochlorophyllgehalte der Thylakoide, nähern sich die verschiedenen Proteinbausteine der Thylakoide einem festen Verhältnis zueinander, das sich oberhalb von 10–14 g Bacteriochlorophyll je mg Zellprotein nicht mehr ändert. Mit Zunahme des Bacteriochlorophyllgehaltes der Zellen steigt der Gehalt an thylakoidspezifischen Proteinen in den Membranen an und der Anteil der für die Cytoplasmamembran spezifischen Komponenten nimmt ab.

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The bacteriochlorophyll content and protein composition of chromatophores (=thylakoids) of Rhodospirillum rubrum during morphogenesis of the photosynthetic apparatus

Summary The correlation between the specific bacteriochlorophyll content of whole cells and the morphogenesis of chromatophores was investigated in Rhodospirillum rubrum. During the first phase after induction of the photosynthetic apparatus bacteriochlorophyll is synthesized without formation of chromatophores. In a second phase chromatophores increases in a linear correlation to the specific bacterichlorophyll content of the cells. In a third phase, when the specific bacteriochlorophyll content of the cells has reached 12–13 g/mg protein, the specific bacteriochlorophyll content of the chromatophores remains constant (100 g/mg protein). Isolated chromatophores from the second phase have smaller diameters, than chromatophores from the third phase. The composition of the protein compounds of isolated chromatophores changes during the development of the chromatophores in a similar fashion as the specific bacteriochlorophyll content of chromatophores does change. With increasing bacteriochlorophyll content of the cells the chromatophore specific proteins in the membranes increase whereas proteins specific for the cytoplasmic membrane decrease until both reach a constant level.

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Verwendete Abkürzungen BChl. Bacteriochlorophyll     

Quantitative DNS-Bestimmungen von Ameisenhirnzellen

Zusammenfassung Gehirnzellen von Myrmica laevinodis-Arbeiterinnen wurden Feulgengefärbt und dabei 1–6 oder 15 Std im Schiffschen Reagens behalten. Die Farbintensität wurde mikrospektrophotometrisch bestimmt. Die Tiere des einen Nestes zeigten ein Extinktionsmaximum nach 1 Std Aufenthalt im Schiffschen Reagens, die eines anderen Nestes nach 5 Std. Die Färbedauer ist also ein weiterer Faktor, der bei quantitativen DNS-Bestimmungen zu berücksichtigen ist.

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Quantitative determination of DNA in feulgen stained brain cells of antsI. The effect of the staining duration on the extinction

Summary Brains of adult Myrmica laevinodis (Hymenoptera, Formicidae) workers were Feulgen stained. They were kept in Schiff's reagens for 1 to 6 hours. In specimens from one nest the colour maximum was reached after 1 hour, in others from a different nest after 5 hours. The colour intensity measured by microspectrophotometry depended on the time the brains stayed in Schiff's reagens. This result means that the time of staying in Schiffs reagens is another factor influencing the amount of measurable DNA.

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Die Untersuchung wurde mit Unterstützung durch den Schweizerischen Nationalfond durchgeführt.

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Die Laborantin Frl. Elisabeth Räber trug mit tatkräftiger, selbständiger Arbeit zum Fortgang der Untersuchung bei. Prof. Dr. F. Ruch stellte uns großzügigerweise sein Mikrospektrophotometer zur Verfügung, wofür ich ihm herzlich danke.     

Die Carotinoide der grünen Schwefelbakterien: Carotinoidzusammensetzung in 18 Stämmen

Summary The composition of the carotenoids in 18 strains of photosynthetic green sulfur bacteria has been investigated.Chlorobactene predominates in all strains; this pigment seems to be characteristic for all photosynthetic green sulfur bacteria. This main carotenoid is accompanied by various amounts of precursors and the hydroxy compounds of all appearing pigments.     

Mortality of Altitude-exposed Mice Infected with Pasturella tularensis

The influence of reduced barometric pressure equivalent to an altitude of 18,000 ft (5,486 m) on the susceptibility of mice to tularemia was investigated by exposing groups of animals to the test environment before, after, or before and after intraperitoneal inoculation of 225 colony-forming units of Pasteurella tularensis. Similarly infected control animals were not exposed to the experimental environment. Two measurements of mortality were employed: (i) the day on which 50% of the mice were dead; and (ii) the number of dead mice on the 8th day. Continuous altitude exposure for 14 days prior to infection had no effect on host susceptibility but exposure after infection significantly increased mortality (P < 0.001).     

Auxintransport und Phototropismus

Summary Short illumination of excised coleoptiles (with or without apex) inhibits the subsequent transport of IAA-2-¹⁴C in these sections during darkness.To a certain extent the inhibition is dependent both on the light intensity and on the duration of illumination. Only the blue region of the visible spectrum is effective.The light induced inhibition is due to a decrease of the quantity of IAA transported; on the other hand, the velocity of transport remains unchanged.The inhibition of auxin transport can be observed only if coleoptiles contain endogenous or fed auxin during the preceding illumination period. Besides illumination inhibition of auxin transport can also be brought about by incubation of coleoptile sections with a previously illuminated IAA/FMN solution.Auxin transformed by peroxidase operates in the same way. The different oxidation products of IAA in the solutions used were identified: The only product which inhibits elongation growth and auxin transport was 3-M. The conversion of IAA to 3-M is accomplished by crude cell-free extracts from corn coleoptiles.An increased formation of labeled 3-M from IAA-2-¹⁴C during illumination of coleoptiles could be demonstrated.Since 3-M is not actively transported in coleoptiles, it must be assumed that 3-M functions as an inhibitor of auxin transport only at its site of formation.It is concluded that the phototropic curvature of coleoptiles and stems is triggered by the photooxidative formation of 3-M from IAA in the side exposed to light. The flow of growth substances will be partly blocked by 3-M in this side and can be directed to the shaded side.On the strength of these findings some phenomena of phototropism (transmission of stimulus, mneme, quantum yield) can easily be explained.

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Abkürzungen FMN Flayinmononucleotid - IES Indol-3-essigsäure - 3-M 3-Methylenoxindol - NES -Naphthylessigsäure Herrn Prof. Dr. L. Brauner zum 70. Geburtstag in Dankbarkeit gewidmet.