Studies of total pulmonary capacity and its subdivisions. I. Normal, absolute and relative values: Hurtado, Alberto, and Boller, Charles: J. Clin. Investigation 12: 793, 1933

Abstract

The cyanobacterium (blue-green alga) Anacystis nidulans was shown to reversibly lose both intracytoplasmic membranes (thylakoids) and pigments when subjected to photooxidative conditions (light, air). For reversible photooxidation to OCl'ur, however, appropriate (pre)treatment was necessary. The bleaching conditions investigated in this paper were (a) low (2 -15°C) or high (48 -50°C) temperatures; (b) metabolic inhibitors (CCCP, DCCD, DCMU) and antibiotics (ehloramphenieol, penicillin); (c) certain divalent cations (Zn, Cd, Pb, Co), as well as agents strongly binding divalent cations, notably Ca2+ (EDTA, EGTA, phosphate).Reversible photooxidation appeared to take place in 2 distinct steps. In the first step, the structural and/or functional integrity of the membranes is somehow impaired by anyone of the conditions or agents employed, thus making the cells I iable to photooxidation proper, whieh occurs in the second step. This model is supported by the observations that (a) the same result, namely thylakoid-free “white” cells, was obtained regardless whether the 2 steps were allowed to proceed simultaneously or whether pretreatment had been applied in a preceding dark period under N2 before the cells were shifted to photooxidative conditions; and (b) only the chlorophyll containing thylakoids underwent photooxidation. Irrespective of the method used, the cytoplasmic memhrane remained essentially intact. Although the pretreatments affected of course both membmnes, photooxidation could occur only in the pigmented thylakoids. In the experiments deseribed here the derangement of the lIlPlIlbranes and, hence, their becoming susceptible towu,rcls photo oxidative atta('k might have resulted from various independent primary events, e.g.: lipid phase transitions in the membranes; or depleting the cells of metabolic energy and/or capability of vital protein turnover; or extracting or displacing Ca2+ from the membranes.Regardless of the treatment used the white cells were devoid of intracytoplasmic membranes. Nevertheless, after transfer to suitable conditions the white cells resynthesized both intracytoplasmic membranes and chlorophyll and eventually resumed growth.