Effects of Far-Red Light on K+ Fluxes in a Colorless Mutant of Chlorella

In a colorless mutant of Chlorella kessleri, far-red light significantlyenhanced the K⁺ efflux. This effect was abolished by the K⁺channel-blocker tetraethylammonium acetate. Using cyanine dyeto monitor membrane potential, we deduced that the K⁺ effluxunder far-red light was probably accompanied by hyperpolarizationof the plasmalemma. (Received August 30, 1993; Accepted November 16, 1993)     

N-Ethylmaleimide Blocks the H+ Pump in the Plasma Membrane of Chara corallina Internodal Cells

The sulfhydryl (SH) modifying reagent N-ethylmaleimide (NEM)was applied to the internodal cells of Chara corallina to studythe role of SH residues in the activity of the plasma membraneH⁺ pump. NEM (1 µM) caused a marked depolarizing shiftof the resting potential by 6410mV (n=7) together with depressionof the conductance peak at around —200 mV, indicatinga marked depression of the H⁺ pump activity. This effect ofNEM was partly reversible, the membrane repolarized and theconductance peak was restored after extracellular washing. TheH⁺ pump inhibitor, dicyclohexylcarbodiimide (DCCD), caused noadditive membrane depolarization and/or depression of the H⁺pump conductance, in the presence of NEM. This suggests thatNEM blocks the H⁺ pump and that SH residues play a pivotal rolein maintaining the H⁺ pump activity in Chara corallina. (Received April 10, 1993; Accepted July 29, 1993)     

Wall appositions induced by ionophore A 23187, CaCl2, LaCl3, and nifedipine in characean cells

Summary The formation of wall appositions (plugs) by ionophore A 23187, CaCl₂, LaCl₃, and nifedipine was studied in mature internodal cells of characeaen algae. CaCl₂ at concentrations above 10^–2M induces thick fibrillar plugs without callose inNitella flexilis. InChara corallina andNitella flexilis ionophore A 23187 (1.25×10^–5 to 5×10^–5M) and LaCl₃ (7.5×10^–5 to 2.5×10^–4M) cause flat appositions which contain callose and have a more granular structure. Plug formation by ionophore A 23187, CaCl₂, and LaCl₃ is pH-dependent and occurs beneath the alkaline regions of the cell. Nifedipine (10^–4 to 10^–5M) induces plugs inNitella flexilis after previous injury. These callose-containing wall appositions consist of a heterogeneous granular core which is covered by a fibrillar layer. The results of this work are compared with previous studies on wound wall formation and chlortetracycline (CTC)-induced plug formation which reveal that abundant coated vesicles occur only when a thick fibrillar wall layer is formed. Neither LaCl₃ nor nifedipine inhibit the formation of CaCl₂- or CTC-plugs. The unusual effects of these substances, which normally act as Ca²⁺ antagonists and therefore should prevent and not induce plug formation, are discussed. It is suggested that La³⁺ mimicks the effects of calcium and that nifedipine binding to the Ca²⁺ channels is altered in the alkaline regions of characean internodes and allows an influx of Ca²⁺.Abbreviations AFW artificial fresh water - CTC chlortetracycline - DCMU dichlorphenyldimethylurea - DMSO dimethylsulfoxide - EGTA ethyleneglycoltetraacetic acid - MES 2-(N-morpholino) ethanesulfonic acid - HEPES N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid - TAPS N-tris[hydroxymethyl]methyl-3-aminopropanesulfonic acid     

PH-DEPENDENCE OF CHLORTETRACYCLINE(CTC)-INDUCED PLUG FORMATION IN NITELLA FLEXILIS (CHARACEAE)1

The formation of chlortetracycline(CTC)-induced wall appositions (callose plugs) in Nitella flexilis (L.)Ag. was pH-dependent in the range between 4.3-8.3. Plug number and plug diameter increased with the pH of the CTC solution. At pH 4.3 plug formation was light-dependent and occurred below the alkaline regions of the cell surface which form during photo synthetic assimilation of HCO₃^?. Inhibition of photosynthesis by 3–(3′,4′-dichlorophenyl)-1, 1-dimethylurea prevented plug formation in the light. Dark-treated cells could be induced to form plugs by raising the pH of the CTC solution. The formation of large but incomplete plugs in the presence of cytochalasin B is explained by the formation of numerous weak alkaline sites. I suggest that CTC enhances locally the Ca²⁺content at the cytoplasm near the plasmamembrane. The ionophoric character of CTC is probably more pronounced at high pH mainly because of a weaker binding with cations and a closer contact with the membrane.     

Visualization of Membrane Calcium and Calmodulin in Embryo Sacs in situ and Isolated from Petunia hybrida L. and Nicotiana tabacum L.

We have used chlorotetracycline (CTC) and fluphenazine (FPZ)as fluorescent probes to visualize the distributional patternsof membrane calcium (mCa²⁺) and the Ca²⁺-receptor protein calmodulin(CaM) in various cell types of unfixed living isolated and unisolatedembryo sacs of Petunia hydrida L. and Nicotiana tabacum L. Ourresults indicate that in the young embryo sacs of Petunia, bothsynergids and the central cell sequester relatively higher amountsof mCa²⁺ and CaM than the egg cell and the antipodals. Much of the mCa²⁺ in the synergids is polarized in its distributionin that the mCa²⁺ is higher towards the micropylar end of thesynergids. Interestingly, in the mature embryo sacs of Petuniaonly one of the two synergids and the egg cell proper manifesta higher level of mCa²⁺. In vivo only one of the synergids inthe young as well as in the mature embryo sacs if Nicotianaconsistently show higher mCa²⁺. In the mature embryo sacs of Petunia the level of CaM is almostuniform in all the cell types except that one of the synergidsand the three antipodal cells show a slightly higher level ofCaM. The possible implications of these findings in the late eventsof vectorial orientation of pollen tube tip, pollen-tube-synergidinteractions and sperm delivery mechanism are discussed.Copyright1993, 1999 Academic Press Membrane-Ca²⁺, calmodulin, living embryo sacs, Petunia, Nicotiana, pollen tube-synergid interaction     

Aluminate-Induced Changes in Morphology and Ultrastructure of Thinopyrum Roots

The effects of aluminate [Al(OH)_4$$$] on the morphology andultrastructure of root cells were studied in the salt-tolerantgrasses Thinopyrum bessarabicum (Savul. and Rayss) A. Lve (2) and Thinopyrum junceum (L.) A. Lve (6) by light and transmissionelectron microscopy. Seedlings were grown in nutrient solutioncontaining 1 mol m^–3 [Al] and 5 mol m^–3 Na₂CO₃ atpH 100. Light microscopy revealed that root tips of [Al]-treated plantsdisplayed bending. Many cells of the cortex in the elongatingregion contained a fibrillar/granular material which renderedthem densely staining. Radial (anticlinal) walls of the epidermalcells were either cleft apart of unusually thickened. Amyloplastsof the central root cap cells contained fewer starch grains,while their distribution was disturbed. Electron microscopy showed that the most serious effects of[Al] toxicity occurred at the cell walls of the epidermal androot cap cells, as they lost their fibrillar fine structureand contained an amorphous electron-dense material distributedall over the wall section. Electron-opaque droplets were encounteredat the plasma membrane region of epidermal cells, while theelectron-dense material observed in the vacuoles of cortex cellscould be aluminate which had accumulated there. Thus, despitethe presence of a barrier to aluminate uptake, some [Al] doesenter the symplast. However, the cytoplasm of many epidermalcells displayed a normal fine structure and contained the usualsubcellular components. Dictyosomes, in particular, were abundantand surrounded by many vesicles denoting an active state. Theseobservations stress the role of cell walls as the major [Al]pool and of the plasma membrane as the ultimate barrier thatprotects the cytoplasm. Results are further discussed in relation to the findings inother plant species and it is concluded that, although aluminateis less toxic than Al³⁺, it causes morphological, structuraland, presumably, functional damage-to the roots of the speciesinvestigated. Key words: Thinopyrum, aluminate toxicity, cell walls, root bending     

Conformational Transitions and Modifications in Ionic Exchange Properties Induced by Alkaline Ions in the Nitella flexilis Cell Wall

The decrease in the cationic exchange capacity (CEC) concomitantto the replacement in the Nitella wall of adsorbed Mn²⁺ ionswas measured in different mixtures of alkaline ions. At lowexternal concentrations, the loss of CEC is enhanced in presenceof Li⁺ ions but is weaker when Na⁺ ions are present in the exchangemixtures. The relative affinity of the wall exchange sites foralkaline ions was Na⁺>K⁺>Rb⁺Cs⁺>Li⁺. As the CEC isprogressively reduced, the wall discrimination between the differentalkaline ions tends to cancel out except for the Na⁺-K⁺ pair.The wall preference for K⁺ is then increased. A diminution ofthe effective pK of the polygalacturonic acids constitutiveof the wall is also observed, while increasing the CEC loss.The simple disruption of divalent cation crosslinks cannot fullyexplain the CEC leakage at low monovalent concentrations. Itis suggested that the alkaline ions also cleave H bonds or solvatation-likebonds between the cell wall polyuronides and then cause a concomitantunfolding of the short pectic chains which involves their solubilization. (Received May 6, 1993; Accepted November 8, 1993)     

Distribution of Vacuolar H+-Pyrophosphatase and a Membrane Integral Protein in a Variety of Green Plants

Vacuolar membranes isolated from several species including fernand moss exhibited pyro-phosphate-dependent H⁺ transport activity.On immunoblot analysis, H⁺ -pyrophosphatase was detected inthe vacuolar membranes. A membrane integral protein of 23,000daltons was not found in the membranes of Chara, Conocephalum,or Kalanchoë. Thus, H⁺-pyrophosphatase may be a universalenzyme among green plants, but the 23-kDa protein is not a commonprotein of central vacuoles. (Received September 10, 1993; Accepted November 29, 1993)     

An Inwardly Rectifying Cation Current across the Plasma Membrane of the Green Alga Eremosphaera viridis

Ion currents across the plasma membrane of the unicellular greenalga Eremosphaera viridis were characterized with electrophysiologicalmethods, especially the two electrode voltage-clamp-technique.Under different conditions, at increased external Cl^–concentrations or after perfusion of different anion channelblockers (A9C (anthracen-9-carboxylic acid), NPPB ((5-nitro-2-3-phenylpropylamino)benzoic acid) and ZnCl₂), increased instantaneous negative currentswere observed. The negative currents were carried by cationfluxes into the cell. The transporter responsible had low selectivityamong potassium and sodium. Additionally also divalent cationswere transported. The cation influx was not affected by thepotassium channel inhibitors TEA (tetraethylammoniumsulfate),Ba²⁺ or Cs⁺ at concentrations of 1 mM, but was strongly reducedby 100 µM AlCl₃. Our results with E. viridis demonstrate,for the first time for an unicellular alga, the existence ofan inwardly rectifying cation current across the plasma membrane.Parallels and differences to inwardly rectifying cation currentsand channels described in plasma membranes of other plant cellsare discussed. (Received May 10, 1993; Accepted September 13, 1993)     

Time Course of Cell Biological Events Evoked in Legume Root Hairs by Rhizobium Nod Factors: State of the Art

In many common legumes, when host-specific nodule bacteria meettheir legume root they attach to it and enter through root hairs.The bacteria can intrude these cells because they instigatein the hairs the formation of an inward growing tube, the infectionthread, which consists of wall material. Prior to infectionthread formation, the bacteria exploit the cell machinery forwall deposition by inducing the hairs to form a curl, in whichthe dividing bacteria become entrapped. In most species, Nodfactor alone (a lipochito-oligosaccharide excreted by bacteria)induces root hair deformation, though without curling, thusmost aspects of the initial effects of Nod factor can be elucidatedby studying root hair deformation. In this review we discussthe cellular events that host-specific Nod factors induce intheir host legume root hairs. The first event, detectable onlya few seconds after Nod factor application, is a Ca²⁺influxat the root hair tip, followed by a transient depolarizationof the plasma membrane potential, causing an increase in cytosolic[Ca²⁺] at the root hair tip. Also within minutes, Nod factorschange the cell organization by acting on the actin cytoskeleton,enhancing tip cell wall deposition so that root hairs becomelonger than normal for their species. Since the remodellingof the actin cytoskeleton precedes the second calcium event,Ca²⁺spiking, which is observed in the perinuclear area, we proposethat the initial cytoskeleton events taking place at the hairtip are related to Ca²⁺influx in the hair tip and that Ca²⁺spikingserves later events involving gene expression. Copyright 2001Annals of Botany Company Review, Nod factor, tip growth, root hair, Rhizobium, legume, cytoskeleton, calcium, symbiosis     

Altered Synthesis and Composition of Cell Wall of Grape (Vitis vinifera L.) Leaves during Expansion and Growth-Inhibiting Water Deficits

The rate and composition of cell wall polysaccharide synthesisduring development and growth-inhibiting water deficits wereinvestigated in leaves of grape (Vitis vinifera L.). The rateof leaf expansion was monitored as plant water status was manipulatedby modulating the supply of irrigation water to potted plantsover several days. The corresponding wall synthesis was determinedby incubating leaf tissue with [¹⁴C]glucose and quantifyingincorporation into wall components. Samples were obtained fromrapidly expanding and mature leaves before, during, and following(recovery from) moderate water deficits. Uptake was approximately2-fold greater for mature leaf tissue than for rapidly expandingtissue at both high and low water status. In contrast, incorporationinto cell wall polysaccharides was 18 to 41% (under low andhigh water status) of uptake in expanding leaves but less than4% in mature tissue. Incorporation of precursor into wall polysaccharideswas insensitive to plant water status in mature leaves, butwas inhibited to less than 50% of well-watered controls in expandingleaves at low water potential. Incorporation of label into cellulose,uronic acid, and neutral sugar fractions was differentiallyaffected by water deficits, with cellulose synthesis apparentlyexhibiting the greatest sensitivity to low water status. Afterrewatering, growth, as well as uptake and incorporation of labelrecovered, although the latter did not attain prestress rates.The results indicate a high sensitivity of wall polysaccharide(particularly cellulose) synthesis to growth-inhibiting waterdeficits. ¹ Supported by United States Department of Agriculture, CompetitiveResearch grant GAM 8502539. (Received November 15, 1989; Accepted January 17, 1990)     

Effect of osmotic shock on auxin-induced cell extension, cell wall changes and acidification in Avena coleoptile segments

The effect of plasma membrane alteration caused by osmotic shockof different strengths on the auxin-induced responses of Avenacoleoptile cells was observed. Osmotic shock brought about by0.5–0.7 M mannitol solution for 10 or 30 min, followedby phosphate-buffer (1 mM, pH 6.0) treatment for 10 min at 4?Ccaused no significant inhibition of auxin-induced cell extension.The osmotic shock did not affect auxin-induced cell wall looseningrepresented by stress-relaxation time and a decrease in thenoncellulosic glucose level of the cell wall. The shock causedonly a temporary inhibition of transmembrane potential and noinhibition of oxygen consumption. However, it inhibited auxin-stimulatedH⁺ secretion which was reversed by 0.1 mM CaCl₂. We concludedthat the Osmotic shock may partly modify the plasma membranerelated to the hydrogen ion pump which interacts with auxin,but this modification which is reflected little by the transmembranepotential and cellular metabolism, is not closely related toauxin-induced cell wall loosening and thus cell extension inAvena coleoptiles. ³ Present address: Department of Botany, Faculty of Science,University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan (Received February 17, 1978; )     

Electrophysiological Evidence for an Electrogenic Proton Pump and the Proton Symport of Glucose in the Marine Fungus Dendryphiella salina

The marine hyphomycete Dendryphiella salina (Suth.) Nicot &Pugh has a resting membrane potential of –250 mV (insidenegative). The respiratory inhibitors sodium azide and FCCPinduced a rapid but reversible depolarization of the membraneof at least 180 mV; sodium azide also caused alkalinizationof the medium. Vanadate brought about significant depolarizationbut this was not always reversible. EDTA induced depolarizationthough to a lesser extent. DIDS and SITS caused a depolarizationof around 30–70 mV which was readily reversible, N-ethylmaleimideirreversibly depolarized the membrane by 180–200 mV. Ouabainhad no effect. When external concentrations of H⁺ , K⁺ , Na⁺or Cl^– were changed singly, only changes in H⁺ affectedmembrane potential, with shifts decreasing with increasing pH.Glucose and 3-O-methyl glucose depolarized the membrane in aconcentration-dependent manner which was enhanced by starvationof the hyphae. Recovery occurred in the presence of the hexose.Glucose caused an alkalinization of the medium, with time characteristicssimilar to the membrane potential changes. It is concluded thatthere is an electrogenic proton pump and a proton—glucosesymporter in D. salina. The retention of proton-based transportsystems suggests a terrestrial origin for the fungus. Key words: Marine fungi, Dendryphiella salina, membrane potential, electrogenic proton pump, proton symport, hexose     

Breakdown phenomena in the Chara membrane

The breakdown phenomenon in the Chara internodal cell was studiedusing the voltage clamp technique. When a slowly hyperpolarizingramp potential pulse was applied to the Chara membrane, thebreakdown occurred with hyperpolarization of about 220 mV. Thebreakdown was observed by less hyperpolarization, if the externalK⁺ concentration was increased. Such a breakdown phenomenonin the Chara membrane was caused principally by a large shiftof the membrane electromotive force toward depolarization. Thisshift frequently exceeded the peak level of the action potential. (Received July 26, 1976; )     

The Role of Calcium and Calmodulin in Carrot Somatic Embryogenesis

The role of Ca²⁺ and calmodulin in carrot somatic embryo formationwas examined. Embryogenic cell clumps were induced to form embryosin medium containing 0–3 mM Ca²⁺. Embryo formation wasnot affected until the concentration of Ca²⁺ was lower than200 µM and after this threshold was reached the percentof embryo formation decreased with lower Ca²⁺ concentrations.Treatment of developing embryos with either verapamil or nifedipine,Ca²⁺ -channel blockers, or the Ca²⁺ ionophore A23187 [GenBank] , inhibitedembryo formation. These results suggest that exogenous Ca²⁺or the maintenance of Ca²⁺ gradients are required for properembryo development. Analysis of membrane-associated Ca²⁺ andtotal membrane distribution using the fluorescent dyes chlorotetracyclineand N-phenyl-1-napthylamine, respectively, indicated changesin the distribution of membranes during embryogenesis withoutany significant alterations in the concentration of Ca²⁺ associatedwith the membranes. In heart- and torpedo-stage embryos, calmodulin-Ca²⁺complexes were localized in regions containing the developingmeristems of both the cotyledon tips and rhizoid regions whiletotal calmodulin protein appeared to be more uniformly distributed.Calmodulin mRNA levels increased slightly when cell clumps wereinduced to form embryos. (Received July 7, 1993; Accepted September 27, 1993)     

Modulation of the Plasma Membrane Electron Transfer System in Root Cells of Limnobium stoloniferum by External pH

The influence of ferricyanide on transmembrane electron transfer,proton secretion, membrane potential, and cytoplasmic pH ofLimnobium stoloniferum (G.F. Mey) Griseb. root cells was investigatedat different external pH HCF III reduction by the roots was accompanied by membrane depolarization,an increase in proton secretion and by alkalinization of thecytoplasm. Change of membrane potential and cytoplasmic pH aswell as transmembrane e^– transfer was more pronouncedat acid external pH. The rate of proton flux was linearly dependenton the rate of electron transfer. The slope of the relationshipwas around 1, independent of external pH The data are in agreement with the hypothesis that electrontransfer at the plasma membrane is directly coupled to protonsecretion. It is suggested that both e^– and redox-coupledH⁺ transport are activated by acid external pH Key words: Plasmalemma redox system, electron transfer, proton transport, pH, membrane potential, Limnobium stoloniferum     

The Membrane Potential of Enzymatically Isolated Nitella expansa Protoplasts as Compared with their Intact Cells

With the enzymatically isolated Nitella protoplasts, sufficientinsertions of micro-electrodes to make a stable measurementof the membrane potential by the conventional method could notbe made because of an ‘elasticity’ of the outermembrane. We developed an effective method in which a micro-electrodecould be inserted after the outer membrane was punctured bypassing an electrical impulse through the micro-electrode. Inthis method, Ca ions play a crucial role in the ‘punching’and ‘healing’ processes of the protoplast membrane. The effects of the cations K⁺, Na⁺, Ca²⁺ and the anions Cl^–,, , on the membrane potentials of Nitella expansa protoplasts were compared with those of intactcells. The membrane potential of protoplasts was less negativethan that of intact cells when concentrations of Na or K, inthe presence of Ca, were below certain levels which increasedwith increasing Ca concentration; and it tended to become identicalto that of intact cells when Na or K concentrations were beyondthose levels. Beyond those levels for K the membrane potentialsof both protoplasts and intact cells typically seemed to bethe Nernst potentials in the presence of 0•1 to 30 molm^–3 Ca²⁺. However, for Na, the difference in potentialsbetween intact cells and protoplasts decreased at much higherconcentrations than for K. Increase of Ca always gave less negativeprotoplast potentials than those in intact cells. Replacementof Ca by Mg did not change the membrane potential of intactcells, although it was deleterious to protoplasts. The cellwall potential of intact cells was also measured by the micro-electrodetechnique and was revealed as a simple Donnan potential, assumingthe fixed negative charge density of 0•8 equivalent perdm³. The membrane potential of intact cells seems to be a significantreflection of the plasmalemma potential which is thought tobe measured directly in their protoplasts in terms of ionicselectivity and concentration dependency of the ion speciesexamined. In addition, increased sensitivity to calcium in protoplastpotentials compared to intact cells is suggested, though themembrane potential of intact cells seems to be largely preservedin their enzymatically isolated protoplasts. Key words: Membrane potential, protoplasts, Nitella expansa, cell wall potential     

The Supramolecular Organization of Red Algal Vacuole Membrane Visualized by Freeze-fracture

The supramolecular organization of the vacuole membrane (orof the membranes of mucilage sacs) in 27 species of red algaeis studied in replicas of rapidly frozen and fractured cells.Intramembranous particle complexes composed of four particles('tetrads' with average diameters between 8·5 and 14·5have been observed in the protoplasmic fracture (PF) face butmost clearly and more frequently in the exoplasmic fracture(EF) face of the vacuole membrane of all red algae investigated.The tetrads lie individually within the vacuole membrane orform clusters in several species and are randomly distributed.In the species Ceramium diaphanum var. strictum and Laurenciaobtusa the intramembranous particle complexes ('tetrads') havebeen observed both in the EF and PF faces of the vacuole membrane;the 'membrane tetrads' at least as regards these two speciesseem to span both the outer and inner leaflets of the vacuolemembrane ('transmembrane particles'). The occurrence of particletetrads in the plasma membrane is probably due to exocytosiseither of the Golgi vesicles or of the mucilage sacs. Tetradfrequency in the EF face of the vacuole membranes of the investigatedred algae varies between 2 and 87 µm^-2, while that ofsingle particles varies between 102 and 695 µm^-2. ThePF face of the vacuole membrane is characterized by a higherparticle density than the EF face. The particle densities ofthe PF and EF faces of the plasma membrane for a given speciesare higher than those of the corresponding fracture faces ofthe vacuole membrane. Some members of Bangiophycidae bear smallerprotein particles (diameter between 8·5 and 10·5nm) in comparison with those of Florideophycidae (diameter between10·5 and 14·5 nm). It is suggested, based uponthe particle tetrads lying in depressions of the vacuole membraneand the origin of vacuoles (mucilage sacs) from ER, that theparticle tetrads originate from the ER or the Golgi complex.Since vacuoles (mucilage sacs) in red algae, along with theGolgi complex, are involved in the synthesis and export of cellsurface polysaccharides, it could be assumed that the 'membrane-tetrads'within the vacuole membrane represent a membrane-bound multienzymecomplex, participating in the synthesis of amorphous extracellularmatrix polysaccharides.Copyright 1993, 1999 Academic Press Red algae, freeze-fracture, vacuole membrane, mucilage sacs, membrane tetrads, supramolecular organization     

Effects of Acriflavine on the Formation of the Plasma Membrane of Escherichia coli

When cells of acriflavine-sensitive (acrA) and acriflavine-resistant(acrA⁺) Escherichia coli K-12 strains were treated with a ratherhigh concentration (100 µg ml^-1) of acriflavine in mediumthat had been adjusted to pH 8.1, distinct whirlpool-like structuresderived from the plasma membrane appeared not only in the acrAcells but also in the acrA⁺ cells. Chemical analysis was performedto determine the lipid composition of the cells by thin-layerchromatography on silica gel and gas-liquid chromatography.The amount of total fatty acids was significantly higher inthe acrA cells than in the acrA⁺ cells, when cells were culturedin the presence of acriflavine. This difference seems to becaused by the greater accumulation of unsaturated fatty acids(palmitoleic and cis-vaccenic acid) in the acrA mutant cellsthan in the acrA⁺ cells and by the acceleration of this accumulationas a result of the presence of the dye. A comparison of phospholipidcontents between the acrA and acrA⁺ cells cultured under acriflavine-freeconditions showed that the former cells contained more phosphatidylethanolamine(PE) and, in particular, more cardiolipin (CL) than the lattercells. However, the situation was reversed in the case of phosphatidylglycerol(PG). Addition of acriflavine to the medium led to a markedincrease in levels of PE and CL in both acrA and acrA⁺ cellsbut an increase in levels of PG was found only in the acrA⁺cells. (Received October 13, 1992; Accepted May 31, 1993)