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EFFECTS OF BICARBONATE ION ON CHLOROPHYLL a FLUORESCENCE TRANSIENTS AND DELAYED LIGHT EMISSION FROM MAIZE CHLOROPLASTS
Author(s) -
Stemler Alan
Publication year - 1974
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1974.tb06503.x
Subject(s) - dcmu , bicarbonate , fluorescence , chemistry , photochemistry , chloroplast , photosystem ii , chlorophyll , chlorophyll fluorescence , ion , photosynthesis , biochemistry , optics , physics , organic chemistry , gene
— Using high‐intensity actinic light, the chlorophyll a fluorescence transient from HCO ‐ 3 ‐depleted chloroplasts shows a rapid initial rise (O → I) followed by a slow phase (I → P). In the presence of HCO ‐ 3 , the O → I rise is delayed but the I → P phase is much more rapid. Using low‐intensity actinic light, the chlorophyll a fluorescence transient from 3‐(3,4‐dichlorophenyl)‐1,1 dimethylurea (DCMU)‐treated chloroplasts is delayed in the presence of HCO ‐ 3 . Bicarbonate increases the amount of delayed light emission from chloroplasts given 10 s illumination with weak blue light (0·4 W/m 2 ). DCMU greatly increases the amount of delayed light seen in the presence of HCO ‐ 3 under these conditions but decreases the amount seen in the absence of HCO ‐ 3 . It is suggested that HCO ‐ 3 may somehow form or stabilize, in the dark, a number of reaction centers corresponding to the S 1 state in the model of B. Forbush, B. Kok and M. McGloin ( Photochem. Photobiol. 14, 307–321, 1971).