Arch. Mikrobiol. 68, 187--190 (1969)

Kurze Mitteilung

A Colorless Chlorella Mutant Containing Thylakoids

MAHASIN S. GERGIS

Max-Planck-Institut fiir Ziichtungsforschung (Erwin-Baur-Institut) Abt. Menke KSln-Vogelsang

Received July 24, 1969

Summary. An electron microscope study of the colorless mutant I 125 of Chlorella vulgaris shows that the algae contain plastids with a lamellar system.

Previous studies with colorless algae revealed the presence of plastids without lamellar system: Prototheca ci/errii (MENKE and F~ICKE, 1962); Polytoma uvella (LAma, 1963); Euglena gracilis (Mol~I]3WR et al., 1963); Astasia longa (RING, 1963); Polytomella agilis (W~BsTE~ et al., 1967) and Nitzschia alba (Sc~r 1969). In higher plants the appearance of the lamellar system is associated with chlorophyll synthesis (s. SPnEY, 1968). In general formation of thylakoids and chlorophyll synthesis are correlated (GIBO~ and G~A~ICK, 1962). The present work reports that in a colorless mutant of Chlorella vulgaris I 125 the leucoplastid contains thylakoids.

The colorless mutant I 125 was isolated from the wild type green Chlorella vulgaris 11 h (Algensammlung des Pflanzenphysiologischen Instituts GSttingen) after treatment with P32-phosphate by SC~W~ZE and FRANDSEN (1960). Mixotro- phic cultures were grown in a light-dark cycle of 14 hours light: 10 hours dark as well as in the dark only (s. Sc~wnl~ZV,, 1965). Under these conditions there was neither chlorophyll nor carotenoid formation (Scmvn]) and Sc~rwARzv,, 1969). Cells were harvested during the lag phase (ca. 4 x 106/ml) by slow eentrifugation, fixed with glutaraldehyde and post fixed with potassium permanganate (s. WANKA, 1968). Fixed specimens were dehydrated gradually (SITTE, 1962) and embedded in Araldit (Serva). The sections were double stained with uranyl acetate (5~ and lead citrate (REYNOLDS, 1963).

This colorless mutant of Chlorella vulgaris (Fig. 1) contains cup- shaped plastids similar to the wild type (So~D~, 1964). In the plastid long separated thylakoids (MENKE, 1965) are observed which do not touch each other, and look essentially similar to those reported for Cyanophyeeae (MENKE, 1961); Rhodophyceae (BoucK, 1962; B~ow~ and W ~ I ~ , 1968). In addition tubules are present in the matrix (MENKE, 1960; PICKET-HEAl"S, 1968) and with aging, starch grains appear

188 M.S. GERGIS:

Fig. 1. Colorless Mutant of Chlorella vulgaris. The leukoplastid, depicted in two portions, shows separated thylakoids and tubules. Magnification • 18.900

between the lamellae. The other cell organelles are similar to those of green Chlorella. However the cell wall is thin in comparison with tha t of the wild type (s. SOEDE~, 1964).

The presence of thylakoids in this colorless m u t a n t is not surprising because different genes are involved in p igment synthesis and membrane formation. I n this connection it is of interest to note t h a t BoGo~A9 et al. (1963) have already described a chlorophyll free m u t a n t of Cyanidium

A Colorless Chlorella Mutant Containing Thy!akoids 189

caldarium with thylakoids. But the Cyanidium mutant contains carote- noids, while our Chlorella mutant lacks carotenoids.

I am greatly indebted to Professor W~EELM ME.Ks. for valuable advice and interest during this investigation. I also wish to thank Dr. GEO~G S C ~ D for ad- vice in electron microscopic technique and Dr. PAUn SCRWA~ZE for providing the necessary material. I am also deeply grateful for the excellent technical assistance of Mrs. F~E~A LIE~REC]IT and Miss MO~K~ SC~ITT.

References

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190 M.S. GERGIS: A Colorless Chlorella Mutant Containing Thylakoids

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MAWASIN S. GERGIS Max-Planck-Institut fiir Ziichtungs- forschung, Abteilung Menke 5000 KSln-Vogelsang