Spectral Changes in Anacystis nidulans Induced by Chilling

Abstract

When Anacystis nidulans, strain TX 20 was grown at 39 C, then rapidly chilled to 0 C, a pigment with a carotenoid-ike spectrum was bleached. This effect was not seen when ceUs which had been grown at 25 C were chiRled. The effect seen in 39 C-grown ceUs was not reversible except under extreme conditions such as beating to near boiling for several minutes. Bleaching could be prevented by prior exposure of cells to glutaraldehyde, but could not be reversed by glutaraldehyde treatment following chiUling. The effect occurred upon chiUling 39 C-grown cells even after extensive heating at 85 C, a treatment which destroys phycocyanin and metabolic activities. 25 C-grown cells were induced to bleach by chiRing when suspended in 50% glycerol. The results are interpreted as indicating a chiUl-induced change in aggregation state of a carotenoid, which changes its specific absorbance.As described in the preceding paper (13), Anacystis nidulans exhibits several specific effects when 39 C-grown cells are chilled to near 0 C which are not seen when 25 C-grown cells are treated in the same manner. These results appear to reflect differences in membranes of cells grown at 39 and 25 C. The work described in this and in the previous paper extends previous observations which demonstrated cold sensitivity in Anacystis (2, 5, 6) and a change in the physical state of Anacystis membranes as they are chilled (10).In this report, an additional effect of chilling A. nidulans is described. Bleaching of a pigment, observable spectrophotometrically, is shown to occur in cells grown at 39 C, but not those grown at 25 C. Evidence is presented that bleaching reflects physical changes within the photosynthetic membranes.MATERIALS AND METHODS A. nidulans, strain TX 20, was grown in continuous cultures as described in the preceding paper (13). Cells were routinely chilled to 0 C by placing them in a darkened 50-ml Erlenmeyer flask, then swirling in an ice water bath. The cell suspension was left in the bath for the duration of the chill time. Cell suspensions required approximately 2 min to reach below 4 C. For chill temperatures above 0 C, cells were placed in a darkened container and incubated in a water bath of appropriate temperature for the desired time. For temperatures below 0 C, cells were pelleted and resuspended in 50% (v/v) In experiments requiring glutaraldehyde fixation, cells were pelleted and resuspended in a 2% (v/v) glutaraldehyde solution in 0.05 M K-phosphate buffer (pH 6.8) of the same temperature as the cell suspension. Cell suspensions were kept in darkness during glutaraldehyde treatment.Experiments requiring heated cells were held in a darkened 50-ml Erlenmeyer flask in a water bath of appropriate temperature. The bath was placed over a hot plate with a magnetic stirrer and the contents slowly stirred during heating. A marble was placed over the flask during heating to prevent excessive evaporation.During chilling experiments, a control aliquot was always kept dark at the growth temperature to serve as a reference...

Primary Role of the Cytoplasmic Membrane in Thermal Acclimation Evidenced in Nitrate-Starved Cells of the Blue-Green Alga, Anacystis nidulans

“…In agreement with previous studies (3,4,13), we found that the absorption spectrum of the alga cells is greatly influenced by chilling pretreatment. An absorption increase occurs at 390 nm, which has been attributed to a conformational change or an aggregation of the zeaxanthin in the membrane, due to a lipid phase transition (13,25,26).…”

The action in vivo of glycine betaine in enhancement of tolerance of Synechococcus sp. strain PCC 7942 to low temperature

“…strains PCC 7942 and PCC 6301 (previously referred to as Anacystis nidulans) (4,8,19,23,34,36). Figure 5 shows that the phase transition of the membrane lipids of the PAM cells first became apparent at 10ЊC and ceased at 2ЊC, with a mid-point temperature at about 6ЊC.…”

“…strain PCC 6301 (previously termed A. nidulans) is caused by the transition of the lipid phase of plasma membranes from the liquid crystalline state to the phase-separated state (19). Since changes in the absorption spectra of carotenoids in intact cells are a good indicator of changes in the lipid phase in Synechococcus (4,8,19,23,34,36), we were able to determine the profiles of temperature dependence of the lipid phase of the plasma membranes in PAM and PAMCOD cells. The results demonstrated that the phase transition of the plasma membranes of PAMCOD cells was shifted toward lower temperatures, compared with that of PAM cells (Fig.…”

Chilling Susceptibility of the Blue-green Alga Anacystis nidulans

“…They seem to possess an evolutional position between bacteria and plants. Therefore, the chilling susceptibility of the blue-green algae can be a link which connects chilling injury and cold shock.A number of studies have been done to reveal that a blue-green alga, Anacystis nidulans, is susceptible to chilling (1,3,4,8,20 Kratz and Myers (9) bubbled with air enriched by 1% CO. Continuous illumination light with an intensity of 6,000 lux was provided from incandescent lamps.…”

“…A number of studies have been done to reveal that a blue-green alga, Anacystis nidulans, is susceptible to chilling (1,3,4,8,20). When the algal cells are exposed to low temperatures near 0 C, the viability of cells declines (20), the photosynthetic 02 evolution, 'This work was supported by Grant- 'To whom reprint requests should be addressed.…”