Archives of Microbiology

, Volume 102, Issue 1, pp 129–137 | Cite as

Effects of diazepam on photosynthesis, respiration, rubidium uptake, and finestructure of Scenedesmus obliquus in synchronous cultures

  • Kurt Ober
Short Communications
Received:

Abstract

Effects of diazepam (Valium) on photosynthesis, chlorophyll/photosynthesis ratios, respiration, uptake of rubidium ions, and ultrastructure of Scenedesmus obliquus synchronized by a light-dark regimen of \(14:\overline {10}\) hrs were determined.

80 and 160 μM diazepam, added to the nutrient medium at the start of the light-dark change (i.e., start of the cell cycle) gradually reduced rates of photosynthesis below the initial rates from the beginning of the experiment. Contents of chlorophyll, however, remained nearly unaffected. Consequently, the diazepam-treated cells had a higher chlorophyll/photosynthesis ratio—also with regard to respiration in order to calculate the gross photosynthesis. The occurrence of photorespiration cannot be assumed. The net influx or rubidium was slightly reduced by 100 μM diazepam 0.5 and 2.0 hrs after the start of the cell cycle and was strongly inhibited after 5 to 14 hrs. 80 and 160 μM diazepam caused separation of thylakoids, formation of giant mitochondria and enlargement of vacuoles.

The results are discussed and it is finally suggested that diazepam acts on different membrane systems. Furthermore an ATP deficiency cannot be excluded.

Key words

Diazepam Benzodiazepines Scenedesmus Ultrastructure Photosynthesis Respiration Rubidium Uptake 

Non-Standard Abbreviations

LDR

light-dark regimen

Glut

glutaraldehyde fixation

Os-Cr

osmium-dichromate post-fixation

Mn

permanganate post-fixation

Pb

lead citrate stain of thin sections

D

dictyosome

M

mitochondrion

N

nucleus

St

starch deposit in the chloroplast

Sp

space between cell wall and plasma-(lemma)

V

vacuole. The scale line indicates 10 μm in low magnification micrographs (Figs. 6 and 9) and 1 μm in the other micrographs

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Copyright information

© Springer-Verlag 1975

Authors and Affiliations

  • Kurt Ober
    • 1
    • 2
  1. 1.Pflanzenphysiologisches Institut der Universität GöttingenGöttingenGermany
  2. 2.Lehrstuhl für Biologie IXFachbereich Biologie der UniversitätRegensburgFederal Republic of Germany

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