Pigments and Photosynthesis in a Carotenoid-Deficient Mutant Of chlamydomonas

Sager, Ruth; Zalokar, Marko

doi:10.1038/182098a0

Cited by 88 publications

(43 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(d) Its chloroplast functions including photosynthesis are dispensable if acetate is provided as a carbon source. Although several pigment mutants of Chlamydomonas have been isolated previously (Sager, 1955;Sager and Zalokar, 1958), including the yellow mutant (y-l) and a brown mutant (br) which accumulates PROTO, this organism has heretofore not been exploited to investigate the genetic control of chlorophyll biosynthesis. Recently we embarked on such a study in Chlamydomonas and have already isolated many mutants which block chlorophyll synthesis and accumulate porphyrin intermediates.…”

mentioning

confidence: 99%

GENETIC CONTROL OF CHLOROPHYLL BIOSYNTHESIS IN CHLAMYDOMONAS

Wang

Boynton

et al. 1974

The Journal of Cell Biology

View full text Add to dashboard Cite

In this report we describe two nonallelic Mendelian protoporphyrin accumulating mutants brs-I and bre-1. Results of experiments with these mutants lead us to postulate that porphyrin biosynthesis branches into light and dark steps between protoporphyrin-IX and magnesium protoporphyrin. We hypothesize that the br e locus controls a dark step while the br s locus either controls a step in the main pathway before the branch or mediates the preparation of the magnesium ion for its insertion into protoporphyrin-IX. The brs-1 mutant is thought to be light sensitive because a block prior to the branch point in the porphyrin pathway prevents chlorophyll formation in either the light or the dark. The brc-1 mutant, which also accumulates protoporphyrin in the dark, forms chlorophyll and chloroplast lamellae when transferred to the light, showing that function of the porphyrin pathway is normal in the light.

show abstract

mentioning

confidence: 99%

GENETIC CONTROL OF CHLOROPHYLL BIOSYNTHESIS IN CHLAMYDOMONAS

Wang

Boynton

et al. 1974

The Journal of Cell Biology

View full text Add to dashboard Cite

show abstract

“…These mutants are frequently sensitive to light, growing better in the dark than in the light when supplied with acetate. Several C. reinhardii mutants, selected as pigment-deficient strains, were found to be photosensitive (5,12,20,21), while others, selected as light-sensitive, included mutants with altered pigmentation (18,19). Some degree of photosensitivity was also associated with PSI and photophosphorylation-deficient mutants (14) even though these mutants were recovered in the light.…”

mentioning

confidence: 99%

Nuclear Suppressors of the Photosensitivity Associated with Defective Photosynthesis in Chlamydomonas reinhardii

Spreitzer

Ogren²

1983

Plant Physiol.

View full text Add to dashboard Cite

“…The absorbance increase at 518 nm (hereafter called A,,,), accompanied by a corresponding absorbance decrease at 475 nm, has since been observed in a variety of plants (4,14) and algae (7,12,23). The pigment producing A,8 has not been identified, although either /3-carotene (6,26) or chl a or b (13,18) has been proposed.…”

mentioning

confidence: 99%

The Necessity for β-Carotene in the 518 Nanometer Absorbance Change

Strichartz¹

1971

Plant Physiol.

View full text Add to dashboard Cite

The identity of the pigment responsible for the light-induced 518 nanometer absorbance change was investigated by extraction and reconstitution of spinach chloroplasts. Heptane extraction of carotene and quinones from lyophilized chloro. plasts removes absorbance changes at 518 and 475 nanometers activated by both laser flash and continuous illumination. Some electron transport activity is always present, even in carotene-and quinone-depleted chloroplasts, but the light-induced pH increase disappears following the first extraction step. Readdition of pure 8-carotene partially restores the 518 and 475 nanometer absorbance changes.Duysens (10) first reported reversible absorbance changes at 518 nm arising from the illumination of Chlorella cells by red light. The absorbance increase at 518 nm (hereafter called A,,,), accompanied by a corresponding absorbance decrease at 475 nm, has since been observed in a variety of plants (4,14) and algae (7,12,23). The pigment producing A,8 has not been identified, although either /3-carotene (6, 26) or chl a or b (13, 18) has been proposed.The present investigation shows that the removal of /3-carotene from chloroplasts completely inhibits the 518 nm absorbance change while only partially inhibiting electron transfer and, by implication, chlorophyll photooxidation. Furthermore, reconstitution of the chloroplasts using pure /3-carotene restores an absorbance change which is spectrally identical with A518- MATERIALS AND METHODSChloroplast Isolation. Chloroplasts were isolated from 60 g of deribbed spinach leaves (Spinacia oleracea). It was imperative that the tissue came from fresh leaves which were picked, washed, and stored in the cold as rapidly as possible. through four layers of cheesecloth and the filtrate was centrifuged at 500g for 30 sec. The supernatant was then centrifuged at i5OOg for 10 min, and the resulting pellet was resuspended in a minimal volume of isolating medium to give a final concentration of 2 to 4 mg chl/ml.Extraction of Chloroplasts. Isolated chloroplasts were lyophilized to dryness. Part of the original pellet was not lyophilized, but was stored in the dark at 0 C to be used as a control sample. An unlyophilized control sample was necessary because lyophilized chloroplasts invariably had lower activities than samples which were lyophilized and then rapidly swirled in heptane before drying and resuspension (cf. 2, 3).Lyophilized chloroplasts, containing about 10 mg of chl, were ground to a powder and shaken in 10 ml of heptane for 2 min on a reciprocal shaker. The suspension was centrifuged, the extract was decanted, a chloroplast sample was withdrawn, and fresh heptane was added. After the final extract was decanted, residual heptane was evaporated under vacuum. The dried, extracted chloroplasts were resuspended in a medium identical to the isolating medium but at pH 7.0. The entire extraction was conducted at 0 to 4 C. Reconstitution. Reconstitution was by a method similar to that of Emster et al. (11). Extracted chloroplasts were incubated w...

show abstract

Pigments and Photosynthesis in a Carotenoid-Deficient Mutant Of chlamydomonas

Cited by 88 publications

References 12 publications

GENETIC CONTROL OF CHLOROPHYLL BIOSYNTHESIS IN CHLAMYDOMONAS

GENETIC CONTROL OF CHLOROPHYLL BIOSYNTHESIS IN CHLAMYDOMONAS

Nuclear Suppressors of the Photosensitivity Associated with Defective Photosynthesis in Chlamydomonas reinhardii

The Necessity for β-Carotene in the 518 Nanometer Absorbance Change

Contact Info

Product

Resources

About