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Chen N, Zhang QG. Linking temperature dependence of fitness effects of mutations to thermal niche adaptation. J Evol Biol 2023; 36:1517-1524. [PMID: 37750539 DOI: 10.1111/jeb.14225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 07/28/2023] [Accepted: 08/23/2023] [Indexed: 09/27/2023]
Abstract
Fitness effects of mutations may generally depend on temperature that influences all rate-limiting biophysical and biochemical processes. Earlier studies suggested that high temperatures may increase the availability of beneficial mutations ('more beneficial mutations'), or allow beneficial mutations to show stronger fitness effects ('stronger beneficial mutation effects'). The 'more beneficial mutations' scenario would inevitably be associated with increased proportion of conditionally beneficial mutations at higher temperatures. This in turn predicts that populations in warm environments show faster evolutionary adaptation but suffer fitness loss when faced with cold conditions, and those evolving in cold environments become thermal-niche generalists ('hotter is narrower'). Under the 'stronger beneficial mutation effects' scenario, populations evolving in warm environments would show faster adaptation without fitness costs in cold environments, leading to a 'hotter is (universally) better' pattern in thermal niche adaptation. We tested predictions of the two competing hypotheses using an experimental evolution study in which populations of two model bacterial species, Escherichia coli and Pseudomonas fluorescens, evolved for 2400 generations at three experimental temperatures. Results of reciprocal transplant experiments with our P. fluorescens populations were largely consistent with the 'hotter is narrower' prediction. Results from the E. coli populations clearly suggested stronger beneficial mutation effects at higher assay temperatures, but failed to detect faster adaptation in populations evolving in warmer experimental environments (presumably because of limitation in the supply of genetic variation). Our results suggest that the influence of temperature on mutational effects may provide insight into the patterns of thermal niche adaptation and population diversification across thermal conditions.
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Affiliation(s)
- Nan Chen
- State Key Laboratory of Earth Surface Processes and Resource Ecology and MOE Key Laboratory for Biodiversity Science and Ecological Engineering, College of Life Sciences, Beijing Normal University, Beijing, China
| | - Quan-Guo Zhang
- State Key Laboratory of Earth Surface Processes and Resource Ecology and MOE Key Laboratory for Biodiversity Science and Ecological Engineering, College of Life Sciences, Beijing Normal University, Beijing, China
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Consequences of mutation accumulation for growth performance are more likely to be resource-dependent at higher temperatures. BMC Ecol Evol 2021; 21:109. [PMID: 34092227 PMCID: PMC8180013 DOI: 10.1186/s12862-021-01846-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 05/31/2021] [Indexed: 11/10/2022] Open
Abstract
Background Mutation accumulation (MA) has profound ecological and evolutionary consequences. One example is that accumulation of conditionally neutral mutations leads to fitness trade-offs among heterogenous habitats which cause population divergence. Here we suggest that temperature, which controls the rates of all biochemical and biophysical processes, should play a crucial role for determining mutational effects. Particularly, warmer temperatures may mitigate the effects of some, not all, deleterious mutations and cause stronger environmental dependence in MA effects. Results We experimentally tested the above hypothesis by measuring the growth performance of ten Escherichia coli genotypes on six carbon resources across ten temperatures, where the ten genotypes were derived from a single ancestral strain and accumulated spontaneous mutations. We analyzed resource dependence of MA consequences for growth yields. The MA genotypes typically showed reduced growth yields relative to the ancestral type; and the magnitude of reduction was smaller at intermediate temperatures. Stronger resource dependence in MA consequences for growth performance was observed at higher temperatures. Specifically, the MA genotypes were more likely to show impaired growth performance on all the six carbon resources when grown at lower temperatures; but suffered growth performance loss only on some, not all the six, carbon substrates at higher temperatures. Conclusions Higher temperatures increase the chance that MA causes conditionally neutral fitness effects while MA is more likely to cause fitness loss regardless of available resources at lower temperatures. This finding has implications for understanding how geographic patterns in population divergence may emerge, and how conservation practices, particularly protection of diverse microhabitats, may mitigate the impacts of global warming. Supplementary Information The online version contains supplementary material available at 10.1186/s12862-021-01846-1.
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Cyclic AMP receptor protein regulates cspE, an early cold-inducible gene, in Escherichia coli. J Bacteriol 2011; 193:6142-51. [PMID: 21926233 DOI: 10.1128/jb.05728-11] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
cspE, a member of the cspA family of cold shock proteins in Escherichia coli, is an early cold-inducible protein. The nucleic acid melting ability and transcription antiterminator activity of CspE have been reported to be critical for growth at low temperature. Here, we show that the cyclic AMP receptor protein (CRP), a global regulator involved in sugar metabolism, upregulates cspE in E. coli. Sequence analysis of the cspE upstream region revealed a putative CRP target site centered at -61.5 relative to the transcription start. The binding of CRP to this target site was demonstrated using electrophoretic mobility shift assays. The presence of this site was shown to be essential for P(cspE) activation by CRP. Mutational analysis of the binding site indicated that the presence of an intact second core motif is more important than the first core motif for CRP-P(cspE) interaction. Based on the promoter architecture, we classified P(cspE) as a class I CRP-dependent promoter. This was further substantiated by our data demonstrating the involvement of the AR1 domain of CRP in P(cspE) transcription. Furthermore, the substitutions in the key residues of the RNA polymerase α-subunit C-terminal domain (α-CTD), which are important for class I CRP-dependent transcription, showed the involvement of 265 and 287 determinants in P(cspE) transcription. In addition, the deletion of crp led to a growth defect at low temperature, suggesting that CRP plays an important role in cold adaptation.
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Cortés S, Salgado JM, Rivas B, Torrado AM, Domínguez JM. Fermentation kinetics and chemical characterisation of vino tostado, a traditional sweet wine from Galicia (NW Spain). JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2010; 90:121-131. [PMID: 20355022 DOI: 10.1002/jsfa.3794] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
BACKGROUND Grapes after harvesting are air dried and pressed in order to concentrate sugars, acids and flavour compounds to produce vino tostado (toasted wine), a wine with intense aroma and flavour notes and high residual sugar concentration. In order to get a better knowledge of the difficulties involved, several fermentations were conducted at 12 and 28 degrees C using 0, 15 and 30 g hL(-1) ammonium sulfate and 0, 25 and 50 g hL(-1) exogenous commercial yeast (Saccharomyces cerevisiae var. bayanus) to study the kinetics of sugar consumption and ethanol, acetic acid and glycerol production. RESULTS Fermentation kinetic parameters were calculated and metal concentrations and antioxidant activity were analysed. CONCLUSION The spontaneous fermentation at 12 degrees C and all fermentations conducted with the commercial yeast gave vino tostado of adequate quality, while the spontaneous fermentation at 28 degrees C was sluggish. High-temperature fermentations led to sweeter wines with higher volumetric productivities, although low-temperature fermentations produced better wines in terms of higher glycerol and lower acetic acid levels. Fructose was the only sugar to be consumed during spontaneous fermentations, while both glucose and fructose were consumed during fermentations of the inoculated musts, with preference for each monosaccharide depending on temperature.
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Affiliation(s)
- Sandra Cortés
- Viticulture and Enology Center of Galicia (EVEGA), Ponte San Clodio s/n, E-32427 Leiro (Ourense), Spain
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Hemoglobin senses body temperature. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2009; 38:589-600. [PMID: 19238378 DOI: 10.1007/s00249-009-0410-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2008] [Revised: 01/20/2009] [Accepted: 01/29/2009] [Indexed: 10/21/2022]
Abstract
UNLABELLED When aspirating human red blood cells (RBCs) into 1.3 mum pipettes (DeltaP = -2.3 kPa), a transition from blocking the pipette below a critical temperature T(c) = 36.3 +/- 0.3 degrees C to passing it above the T(c) occurred (micropipette passage transition). With a 1.1 mum pipette no passage was seen which enabled RBC volume measurements also above T(c). With increasing temperature RBCs lost volume significantly faster below than above a T(c) = 36.4 +/- 0.7 (volume transition). Colloid osmotic pressure (COP) measurements of RBCs in autologous plasma (25 degrees C < or = T < or = 39.5 degrees C) showed a T (c) at 37.1 +/- 0.2 degrees C above which the COP rapidly decreased (COP transition). In NMR T(1)-relaxation time measurements, the T(1) of RBCs in autologous plasma changed from a linear (r = 0.99) increment below T(c) = 37 +/- 1 degrees C at a rate of 0.023 s/K into zero slope above T(c) (RBC T(1) transition). IN CONCLUSION An amorphous hemoglobin-water gel formed in the spherical trail, the residual partial sphere of the aspirated RBC. At T(c), a sudden fluidization of the gel occurs. All changes mentioned above happen at a distinct T(c) close to body temperature. The T(c) is moved +0.8 degrees C to higher temperatures when a D(2)O buffer is used. We suggest a mechanism similar to a "glass transition" or a "colloidal phase transition". At T(c), the stabilizing Hb bound water molecules reach a threshold number enabling a partial Hb unfolding. Thus, Hb senses body temperature which must be inscribed in the primary structure of hemoglobin and possibly other proteins.
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Affiliation(s)
- A Rodríguez-Navarro
- Departamento de Biotecnología, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid, 28040, Madrid, Spain.
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Loray MA, De Figueroa LI, Höfer M. Monosaccharide uptake in a yeast hybrid produced by protoplast fusion. Folia Microbiol (Praha) 1997; 42:239-41. [PMID: 9378419 DOI: 10.1007/bf02818992] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- M A Loray
- PROIMI, Universidad Nacional de Tucumán, Argentina
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Toxicity of octanoic acid in Saccharomyces cerevisiae at temperatures between 8.5 and 30°C. Enzyme Microb Technol 1995. [DOI: 10.1016/0141-0229(94)00111-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Severin J, Langel P, Höfer M. Analysis of the H+/sugar symport in yeast under conditions of depolarized plasma membrane. J Bioenerg Biomembr 1989; 21:321-34. [PMID: 2545668 DOI: 10.1007/bf00762724] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
H+/sugar symport in the obligatory aerobic yeast Rhodotorula glutinis was analyzed under conditions where the plasma membrane was selectively depolarized by the lipophilic cation tetraphenylphosphonium (TPP+). Control experiments showed that this treatment did not impair the transmembrane delta pH, the cell energy charge, and the function of plasma membrane H+-ATPase. The kinetic data were fitted to elementary functions derived from a model constructed on the basis of some simplifying premises for ordered (either C + H+ + S or C + S + H+) and random reaction mechanisms. In addition, the comparison of the kinetic parameters in fully energized and depolarized cells provided information about the free carrier charge. It was concluded that the binding sequence of formation of the ternary carrier/H+/substrate complex follows a random mechanism and that the carrier bears a negative charge.
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Affiliation(s)
- J Severin
- Botanisches Institut der Universität, Bonn, FRG
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Measurement of plasma membrane potentials of yeast cells with glass microelectrodes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 1986. [DOI: 10.1016/0005-2736(86)90240-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Schulz B, H�fer M. Utilization of lactose in non-respiring cells of the yeast Debaryomyces polymorphus. Arch Microbiol 1986. [DOI: 10.1007/bf00470873] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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12
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Höfer M, Nicolay K, Robillard G. The electrochemical H+ gradient in the yeast Rhodotorula glutinis. J Bioenerg Biomembr 1985; 17:175-82. [PMID: 4040135 DOI: 10.1007/bf00751060] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The electrochemical gradient of protons, delta mu H+, was estimated in the obligatory aerobic yeast Rhodotorula glutinis in the pH0 range from 3 to 8.5. The membrane potential, delta psi, was measured by steady-state distribution of the hydrophobic ions, tetraphenylphosphonium (TPP+) for negative delta psi above pH0 4.5, and thiocyanate (SCN-) for positive delta psi below pH0 4.5. The chemical gradient of H+ was determined by measuring the chemical shift of intracellular Pi by 31P-NMR at given pH0 values. The values of pHi increased almost linearly from 7.3 at pH0 3 to 7.8 at pH0 8.5. In the physiological pH0 range from 3.5 to 6, delta mu H+ was fairly constant at values between 17-18 KJ mol-1, gradually decreasing at pH0 above 6. In deenergized cells, the intracellular pHi decreased to values as low as 6, regardless of whether the cell suspension was buffered at pH0 4.5 or 7.5. There was no membrane potential detectable in deenergized cells.
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Transport of an anionic substrate by the H+/monosaccharide symport inRhodotorula gracilis: Only the protonated form of the carrier is catalytically active. J Membr Biol 1984. [DOI: 10.1007/bf01868441] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Abstract
In a newly formulated growth medium lacking Na+ and NH4+, Saccharomyces cerevisiae grew maximally at 5 microM K+. Cells grown under these conditions transported K+ with an apparent Km of 24 microM, whereas cells grown in customary high-K+ medium had a significantly higher Km (2 mM K+). The two types of transport also differed in carbonyl cyanide-m-chlorophenyl hydrazone sensitivity, response to ATP depletion, and temperature dependence. The results can be accounted for either by two transport systems or by one system operating in two different ways.
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15
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Künemund A, Höfer M. Passive fluxes of K+ and H+ in wild strain and nystatin-resistant mutant of Rhodotorula gracilis (ATCC 26194). BIOCHIMICA ET BIOPHYSICA ACTA 1983; 735:203-10. [PMID: 6684954 DOI: 10.1016/0005-2736(83)90294-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The passive fluxes of protons and potassium ions have been studied in the obligatory aerobic yeast Rhodotorula gracilis. The cellular energy metabolism was suspended by introducing anaerobic conditions. The H+-permeability of the plasma membrane was modified by adding an uncoupler under both aerobic and anaerobic conditions. Unfortunately, the plasma membrane of R. gracilis was insensitive to K+-ionophores. The passive flows of H+ and K+ under anaerobic and/or uncoupled conditions were electrically coupled and exhibited a constant stoicheiometry of 1:1. The H+ permeability of the plasmalemma was shown to determine the velocity of the passive K+-H+ exchange. The nystatin-resistant mutant M 67 displayed distinctly lower permeability for both H+ and K+, which can explain the observed differences in some transport characteristics of the two strains. In order to account for the properties of passive K+ flows, a membrane-potential-gated channel for K+ has been proposed. Evidence is presented that the inhibitor of the plasmalemma-bound H+-ATPase, N,N'-dicyclohexylcarbodiimide (DCCD), reduced at first the permeability for both K+ and H+ and only upon prolonged incubation the ATPase itself. Since DCCD effected an immediate hyperpolarization of the membrane potential, it has been concluded that the H+ does not slip through the H+-ATPase under deenergized conditions.
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Höfer M, Thiele OW, Huh H, Hunneman DH, Mracek M. A nystatin-resistant mutant of Rhodotorula gracilis. Transport properties and sterol content. Arch Microbiol 1982; 132:313-6. [PMID: 6891206 DOI: 10.1007/bf00413381] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
A nystatin-resistant mutant of Rhodotorula gracilis was obtained by treatment of the wild strain cells with N-methyl-N-nitro-N-nitrosoguanidine and selected on agar plates containing 150 micrograms nystatin/ml. Three important transport functions of the plasma membrane of mutant cells: the accumulation of monosaccharides, the generation and maintenance of the pH-gradient and of the membrane potential, as well as the cell respiration were insensitive to at least 10(-5) M nystatin. This concentration of nystatin inhibited completely all these processes in wild strain cells. Analysis of cellular sterols revealed a defect of ergosterol biosynthesis in the mutant, which was localized at the last oxidative step between 5,6-dihydroergosterol and ergosterol.
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Proton pumps of the plasmalemma of the yeast Rhodotorula gracilis Their coupling to fluxes of potassium and other ions. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 1981. [DOI: 10.1016/0005-2736(81)90172-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Aldermann B, Ho¨fer M. The active transport of monosaccharides by the yeastMetschnikowia reukaufii: Evidence for an electrochemical gradient of H+ across the cell membrane. ACTA ACUST UNITED AC 1981. [DOI: 10.1016/0147-5975(81)90012-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Srivastava V, Misra PC. Effect of endosulfan on plasma membrane function of the yeast Rhodotorula gracilis. Toxicol Lett 1981; 7:475-80. [PMID: 7195616 DOI: 10.1016/0378-4274(81)90096-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The effects of endosulfan on Rhodotorula gracilis cells are varied and concentration-dependent. They are exhibited as increased rate of respiration, retardation in pH-recovering activity of cell suspensions and loss in the rate or D-xylose uptake. The temperature dependence of sugar uptake indicated that endosulfan reacts with some membrane component(s).
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Persell R, Haschemeyer AE. Effects of temperature on L-leucine transport in toadfish liver in vivo. BIOCHIMICA ET BIOPHYSICA ACTA 1980; 602:653-60. [PMID: 7437427 DOI: 10.1016/0005-2736(80)90343-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The effect of body temperature in the 4--30 degrees C range on L-leucine uptake by toadfish liver in vivo was examined by means of a single-injection pulse technique. The ratio of [14C]leucine to [3H]mannitol or [3H]inulin in blood leaving the liver was measured as a function of time after hepatic portal vein injection. Recoveries of the two isotopes in liver and [14C]leucine incorporation into protein were determined. The Q10 value for influx was 3.8, that for efflux 2.8. At all temperatures, the leucine influx was 8--10-times higher than its incorporation into protein. The directly energy-linked reactions appear to be the main site of increased temperature sensitivity at low temperatures.
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Heller KB, Höfer M. Temperature dependence of the apparent affinity and the maximum velocity of the membrane-bound monosaccharide transport system in the yeast Rhodotorula gracilis. BIOCHIMICA ET BIOPHYSICA ACTA 1978; 514:172-7. [PMID: 568938 DOI: 10.1016/0005-2736(78)90087-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Analysis of the temperature dependence of the monosaccharide transport system in the yeast Rhodotorula gracilis (ATCC 26194, CBS 6681), as tested with D-xylose, revealed that the apparent affinity of the transport system, measured as the reciprocal of the half-saturation constant KT, increased when transport velocity was stimulated by temperature (15--30 degrees C) and decreased when the rate of uptake was reduced at temperatures aboce 30 degrees C. Breaks in Arrhenius plots were accompanied by corresponding breaks in van't Hoff plots. Whereas untreated cells exhibited in the van't Hoff plot a discontinuity at 28--30 degrees C this was not observed in heat-treated cells (at either 37 or 45 degrees C). In heat-treated cells the maximum transport velocity was always lower and the apparent affinity higher than in untreated cells at the same temperature; the optimum temperature for both transport velocity and apparent affinity was shifted to higher values. The data are interpreted in terms of a reversible phase transition of membrane lipids effecting an irreversible alteration of membrane structure. The temperature-induced reversible alkalinization of unbuffered yeast suspensions supports this interpretation.
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Evidence for interactions between the energy-dependent transport of sugars and the membrane potential in the yeastRhodotorula gracilis (Rhodosporidium toruloides). J Membr Biol 1978. [DOI: 10.1007/bf01871695] [Citation(s) in RCA: 68] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Barnett JA, Sims AP. Some physiological observations on the uptake of D-glucose and 2-deoxy-D-glucose by starving and exponentially-growing yeasts. Arch Microbiol 1976; 111:185-92. [PMID: 797335 DOI: 10.1007/bf00446567] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Some methods for measuring the uptake of sugars by yeasts were investigated critically. A study was made of the effects of starvation of Pichia pinus, Candida utilis, Saccharomyces cerevisiae and Rhodosporidium toruloides on their uptake of D-glucose and 2-deoxy-D-glucose. Marked changes in the rates of uptake of these sugars occured during 10 h of starvation, including (a) an immediate increase of up to 75% above that for growing cells and (b) a continuous decline to as little as 4%. Each yeast behaved differently. The rates did not remain constant during the periods of starvation often used for studies on the transport of sugars into yeasts. For Pichia pinus, there were striking differences, associated with starvation, between the transport of 2-deoxy-D-glucose and D-glucose, despite evidence that the two sugars enter this yeast by means of the same carrier. Some physiological explanations for these findings are discussed.
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Dürr M, Boller T, Wiemken A. Polybase induced lysis of yeast spheroplasts. A new gentle method for preparation of vacuoles. Arch Microbiol 1975; 105:319-27. [PMID: 242301 DOI: 10.1007/bf00447152] [Citation(s) in RCA: 89] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The polybasic macromolecules DEAE-dextran (diethylaminoethyl-dextran, molecular weight 500000) and poly-DL-lysine (molecular weight 30000-70000) were absorbed with a high affinity by spheroplasts of Candida utilis and subsequently, induced lysis. The extent of lysis of spheroplasts and of the liberated vacuoles was studied under various conditions using alpha-glucosidase activity and soluble arginine as cytoplasmic and vacuolar markers, respectively. Adsorption of polybases was rapidly completed even at 0 degrees C; however, with small doses, lysis was poor at 0-12 degrees C and extensive at temperatures above 12 degrees C. This permitted the completion of adsorption before initiating lysis. The purified vacuoles were also sensitive to polybases though less so than the spheroplasts; however, after lysis of spheroplasts the liberated vacuoles were well protected against the action of polybases. A treatment with polybases which disrupted more than 99% of the spheroplasts left at least 70% of the vacuoles intact. Potassium chloride in high concentrations and calcium chloride in low concentrations inhibited polybase induced lysis of spheroplasts by preventing or even reversing the polybase adsorption. A polyacidic macromolecule, dextran sulfate, could prevent but not reverse the adsorption of polybase and subsequent lysis. Metabolic inhibitors reduced the susceptibility of spheroplasts to polybase induced lysis. Vacuoles isolated from polybase lysed spheroplasts still contained large pools of soluble amino acids, and their ability to transport arginine specifically is a further indication of their functional integrity.
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