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Mohammad K, Appasani SL, Ito M, Percopo C, Desai SA. Optimized plasmid loading of human erythrocytes for Plasmodium falciparum DNA transfections. Int J Parasitol 2024:S0020-7519(24)00081-X. [PMID: 38719176 DOI: 10.1016/j.ijpara.2024.04.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 03/06/2024] [Accepted: 04/30/2024] [Indexed: 05/16/2024]
Abstract
In vitro modification of Plasmodium falciparum genes is the cornerstone of basic and translational malaria research. Achieved through DNA transfection, these modifications may entail altering protein sequence or abundance. Such experiments are critical for defining the molecular mechanisms of key parasite phenotypes and for validation of drug and vaccine targets. Despite its importance, successful transfection remains difficult and is a resource-intensive, rate-limiting step in P. falciparum research. Here, we report that inefficient loading of plasmid into erythrocytes limits transfection efficacy with commonly used electroporation methods. As these methods also require expensive instrumentation and consumables that are not broadly available, we explored a simpler method based on plasmid loading through hypotonic lysis and resealing of erythrocytes. We used parasite expression of a sensitive NanoLuc reporter for rapid evaluation and optimization of each step. Hypotonic buffer composition, resealing buffer volume and composition, and subsequent incubation affected plasmid retention and successful transfection. While ATP was critical for erythrocyte resealing, addition of Ca++ or glutathione did not improve transfection efficiency, with increasing Ca++ concentrations proving detrimental to outcomes. Compared with either the standard electroporation method or a previously reported hypotonic loading protocol, the optimized method yields greater plasmid loading and higher expression of the NanoLuc reporter 48 h after transfection. It also produced significantly faster outgrowth of parasites in transfections utilizing either episomal expression or CRISPR-Cas9 mediated integration. This new method produces higher P. falciparum transfection efficiency, reduces resource requirements and should accelerate molecular studies of malaria drug and vaccine targets.
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Affiliation(s)
- Kashif Mohammad
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Sri Lalana Appasani
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Mai Ito
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Caroline Percopo
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Sanjay A Desai
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA.
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2
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Literature Alerts. J Microencapsul 2008. [DOI: 10.3109/02652048609049586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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3
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Literature Alerts. J Microencapsul 2008. [DOI: 10.3109/02652048509033845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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4
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Burger KN, Staffhorst RW, De Kruijff B. Interaction of the anti-cancer drug cisplatin with phosphatidylserine in intact and semi-intact cells. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1419:43-54. [PMID: 10366669 DOI: 10.1016/s0005-2736(99)00052-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The anti-cancer drug cisplatin (cis-diamminedichloroplatinum(II)) forms a stable coordination complex with phosphatidylserine (PS) in model membrane systems (Speelmans et al., Biochemistry 36 (1997) 10545-10550). Because a similar interaction in vivo would be expected to have important physiological implications we studied cisplatin-PS interaction in human erythrocytes and tumor cell lines. Although cisplatin was efficiently taken up by intact erythrocytes, a cisplatin-PS complex was only detected in cells which had lysed as a result of prolonged storage or hypotonic shock. Despite the use of highly sensitive detection methods, and despite efficient cellular uptake of cisplatin, a complex could also not be detected in four human tumor cell lines, unless cells were permeabilized. In experiments in which cisplatin was incubated with PS-containing liposomes in the presence of an alternative cellular substrate, such as reduced glutathione, the relative affinity of cisplatin for PS was found to be low. Moreover, loading erythrocyte ghosts with physiological concentrations of glutathione strongly reduced cisplatin-PS complexation. Thus, in intact (tumor) cells a complex is not detected, most likely, because of the presence of higher affinity substrates. Though a transient complexation of cisplatin to PS cannot be excluded, our data suggest that cisplatin-PS does not play a direct role in the cellular (cyto)toxicity of cisplatin.
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Affiliation(s)
- K N Burger
- Department of Biochemistry of Membranes, Center for Biomembranes and Lipid Enzymology, Institute of Biomembranes, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
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5
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Artmann GM, Kelemen C, Porst D, Büldt G, Chien S. [Cellular engineering: crash tests with human erythrocytes reveal hidden properties of cellular proteins]. BIOMED ENG-BIOMED TE 1998; 43 Suppl:446-7. [PMID: 9859436 DOI: 10.1109/iembs.1998.746073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- G M Artmann
- Labor für Angewandte Zellbiophysik, FH Aachen-Abteilung Jülich
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6
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Artmann GM, Kelemen C, Porst D, Büldt G, Chien S. Temperature transitions of protein properties in human red blood cells. Biophys J 1998; 75:3179-83. [PMID: 9826638 PMCID: PMC1299989 DOI: 10.1016/s0006-3495(98)77759-8] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Human red blood cells (RBC) undergo a sudden change from blocking to passing through 1.3 +/- 0.2-micrometer micropipettes at a transition temperature (Tc) of 36.4 degrees C. For resealed RBC ghosts this transition occurs at 28.3 degrees C (Tg). These findings are attributed to an elastomeric transition of hemoglobin from being gel-like to a fluid and to an elastomeric transition of membrane proteins such as spectrin. Spectrin shows a uniform distribution along the aspirated RBC tongue above Tg in contrast to the linear gradient below Tg.
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Affiliation(s)
- G M Artmann
- Department of Cell Biophysics, Aachen University of Applied Sciences, Ginsterweg 1, D-52428 Jülich, Germany.
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7
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MacPhee PJ, Michel CC. Fluid uptake from the renal medulla into the ascending vasa recta in anaesthetized rats. J Physiol 1995; 487:169-83. [PMID: 7473246 PMCID: PMC1156607 DOI: 10.1113/jphysiol.1995.sp020869] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
1. We have investigated fluid movements between superficial ascending vasa recta (AVR) and the interstitium of exposed papillae of the renal medullae in 15-day-old Sprague-Dawley rats anaesthetized with Hypnorm and Hypnovel. 2. Using a development of the red cell micro-occlusion technique, fluid filtration and reabsorption rates per unit area of vessel wall (Jv/A) were determined in 54 single perfused AVR at known microvascular pressures (Pc). The relation between Jv/A and Pc was non-linear suggesting hydraulic permeabilities (Lp) of 50-100 x 10(-7) cm s-1 cmH2O-1 when Pc was between 0-10 cmH2O and 150-200 x 10(-7) cm s-1 cmH2O-1 when Pc was 10-15 cmH2O. 3. Rates of fluid reabsorption into the AVR estimated by a densitometric technique in a further fourteen vessels were consistent with Lp values of 50-100 x 10(-7) cm s-1 cmH2O-1 when Pc was -2 to 0 cmH2O. 4. The effective oncotic pressures of perfusates containing bovine serum albumin (BSA) were consistent with minimum values for the reflection coefficients of the walls of the AVR to BSA of between 0.59 and 0.72. 5. The concentration of native serum albumin in the papillary interstitial fluid was 9.1 +/- 0.6 mg ml-1 (mean +/- S.E.M., n = 16, from 9 rats), which is approximately 25% of the plasma level. 6. After their microinjection into the medullary interstitium, Patent Blue V and Evans Blue-albumin cleared within 1 min. There was no evidence of preferential movement of either dye towards the base of the exposed renal medulla. 7. Because Lp of the AVR is high, mean pressures of only approximately 3 cmH2O are necessary to account for the total clearance of fluid from the medullary interstitium into the AVR. From published data and from our own observations, it appears that differences in hydrostatic and oncotic pressure across the walls of the AVR are more than sufficient to provide this driving force. The possibility of the clearance of protein from the interstitium into the AVR is discussed.
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Affiliation(s)
- P J MacPhee
- Department of Physiology & Biophysics, St Mary's Hospital Medical School, Imperial College of Science, Technology and Medicine, London, UK
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8
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Friederichs E, Farley RA, Meiselman HJ. Influence of calcium permeabilization and membrane-attached hemoglobin on erythrocyte deformability. Am J Hematol 1992; 41:170-7. [PMID: 1415191 DOI: 10.1002/ajh.2830410306] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The present study was designed to evaluate the influence of intracellular calcium [Ca]i regulated membrane attached hemoglobin (Hbm) on the deformability of human RBC and ghosts. [Ca]i of RBC was elevated via the ionophore A23187 (10 microM); the deformability of RBC and resealed ghosts was determined via measuring RBC and ghost transit times through 5 microns diameter pores with the Cell Transit Analyzer (CTA). Salient results included: (1) significantly increased RBC levels of Hbm following ionophore treatment; (2) elevated Hbm with increasing lysing medium calcium concentration (0-5 mM); (3) decreased deformability of both intact RBC and ghosts with increasing Hbm and significant (P less than 0.02 or better) linear relationships between Hbm and RBC or ghost transit times; and (4) an increased sensitivity to ionophore treatment/membrane attached hemoglobin for the higher percentiles of the CTA transit time distribution (i.e., for more rigid subpopulations). Our results thus indicate that calcium-induced interaction of hemoglobin with the RBC membrane produces cellular rheological changes; in addition, they demonstrate the usefulness of the CTA system in measuring both average RBC rheologic behavior and the distribution of cellular rheologic properties within an erythrocyte population.
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Affiliation(s)
- E Friederichs
- Department of Physiology and Biophysics, University of Southern California, School of Medicine, Los Angeles 90033
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Ferrari P, Torielli L, Salardi S, Rizzo A, Bianchi G. Na+/K+/Cl- cotransport in resealed ghosts from erythrocytes of the Milan hypertensive rats. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1111:111-9. [PMID: 1390856 DOI: 10.1016/0005-2736(92)90280-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The erythrocytes (RBC) of the Milan hypertensive rats (MHS) have a smaller volume and faster Na+/K+/Cl- cotransport than RBC from normotensive controls (MNS). The difference in Na+/K+/Cl- cotransport is no longer present in inside-out Vesicles (IOV) of RBC membrane. To differentiate between cytoplasmic or membrane skeleton abnormalities as possible causes of these differences. Resealed ghosts (RG) were used to measure ion transport systems. The following results have been obtained: (1) RG from MHS have a smaller volume than MNS (mean +/- S.E. 20.7 +/- 0.45 vs. 22.09 +/- 0.42 fl, P < 0.05). (2) RG showed a bumetanide-sensitive Na efflux that retains the characteristics of the Na+/K+/Cl- cotransport of the original RBC: it is K(+)- and Cl(-)-sensitive and dependent on the intracellular Na+ concentration. (3) The Na+/K+/Cl- cotransport was faster in RG from MHS than in those from MNS (mean +/- S.E. 0.095 +/- 0.01 vs. 0.066 +/- 0.01 rate constant h-1, P < 0.01). These results, together with those of IOV, support the hypothesis that an abnormality in the membrane skeletal proteins may play a role in the different Na+/K+/Cl- cotransport modulation between MHS and MNS erythrocytes.
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Affiliation(s)
- P Ferrari
- Prassis Sigma-Tau Research Institute, Milan, Italy
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Zhang ZH, Solomon AK. Effect of pCMBS on anion transport in human red cell membranes. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1106:31-9. [PMID: 1316163 DOI: 10.1016/0005-2736(92)90218-b] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The kinetics of binding of the mercurial sulfhydryl reagent, pCMBS (p-chloromercuribenzene sulfonate), to the extracellular site(s) at which pCMBS inhibits water and urea transport across the human red cell membrane, have previously been characterized. To determine whether pCMBS binding alters Cl- transport, we measured Cl-/NO3- exchange by fluorescence enhancement, using the dye SPQ (6-methoxy-N-(3-sulfopropyl)quinolinium). An essentially instantaneous extracellular phase of pCMBS inhibition is followed by a much slower intracellular phase, correlated with pCMBS permeation. We attribute the instantaneous phase to competitive inhibition of Cl- binding to band 3 by the pCMBS anion. The ID50 of 2.0 +/- 0.1 mM agrees with other organic sulfonates, but is very much greater than that of pCMBS inhibition of urea and water transport, showing that pCMBS reaction with water and urea transport inhibition sites has no effect on anion exchange. The intracellular inhibition by 1 mM pCMBS (1 h) is apparently non-competitive with Ki = 5.5 +/- 6.3 mM, presumably an allosteric effect of pCMBS binding to an intracellular band 3-related sulfhydryl group. After N-ethylmaleimide (NEM) treatment to block these band 3 sulfhydryl groups, there is apparent non-competitive inhibition with Ki = 2.1 +/- 1.2 mM, which suggests that pCMBS reacts with one of the NEM-insensitive sulfhydryl groups on a protein that links band 3 to the cytoskeleton, perhaps ankyrin or bands 4.1 and 4.2.
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Affiliation(s)
- Z H Zhang
- Biophysical Laboratory, Harvard Medical School, Boston, MA
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11
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Vlasov VV, Ivanova EM, Krendelev YD, Kutyavin IV, Ovander MN, Ryte AS, Svinarchuk FP, Yakubov LA. Sendai virus envelopes and erythrocyte ghosts as membrane vehicles for transport of the reactive oligonucleotide derivatives into the cells. ACTA ACUST UNITED AC 1989. [DOI: 10.7124/bc.0000d3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- V. V. Vlasov
- Institute of Bioorganic Chemistry, Siberian Branch of the Academy of Sciences of the USSR
| | - E. M. Ivanova
- Institute of Bioorganic Chemistry, Siberian Branch of the Academy of Sciences of the USSR
| | - Yu. D. Krendelev
- Institute of Bioorganic Chemistry, Siberian Branch of the Academy of Sciences of the USSR
| | - I. V. Kutyavin
- Institute of Bioorganic Chemistry, Siberian Branch of the Academy of Sciences of the USSR
| | - M. N. Ovander
- Institute of Molecular Biology and Genetics, Academy of Sciences of the Ukrainian SSR
| | - A. S. Ryte
- Institute of Bioorganic Chemistry, Siberian Branch of the Academy of Sciences of the USSR
| | - F. P. Svinarchuk
- Institute of Bioorganic Chemistry, Siberian Branch of the Academy of Sciences of the USSR
| | - L. A. Yakubov
- Institute of Bioorganic Chemistry, Siberian Branch of the Academy of Sciences of the USSR
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12
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Ito T, Kon H. A flow EPR study of deformation and orientation characteristics of erythrocyte ghosts: a possible effect of an altered state of cytoskeletal network. J Membr Biol 1988; 101:57-65. [PMID: 2835487 DOI: 10.1007/bf01872820] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Using the flow EPR technique, we investigated the resealed ghost deformability in shear flow and the effects of the altered state of cytoskeletal network induced by hypotonic incubation of ghosts. Isotonically resealed ghosts in the presence of Mg-ATP, in which alteration of cytoskeletal network is not effected, have smooth biconcave discoid shapes, and show a flow orientation and deformation behavior similar to that of erythrocytes, except that higher viscosities are required to induce the same degrees of deformation and orientation as in erythrocytes. The flow behavior of resealed ghosts is Mg-ATP dependent, and the shape of the ghosts resealed without Mg-ATP is echinocytic. In contrast, the ghosts resealed by hypotonic incubation show a markedly reduced deformability even with Mg-ATP present. Nonreducing, nondenaturing polyacrylamide gel electrophoresis (PAGE) of the low ionic strength extracts from hypotonically resealed ghosts reveals a shift of the spectrin tetramer-dimer equilibrium toward the dimers. In the maleimide spin-labeled ghosts, the ratios of the weakly immobilized to the strongly immobilized EPR intensities are larger in hypotonically resealed ghosts than in the isotonically resealed ghosts, indicating an enhanced mobility in the spectrin structure in the former. Photomicrographs of hypotonically resealed ghosts show slightly stomatocytic transformations. These data suggest that the shape and the deformability loss in hypotonically resealed ghosts are related to an alteration of the spectrin tetramer-dimer equilibrium in the membrane. Thus, the shift of the equilibrium is likely to affect the regulation of the membrane deformability both in normal and pathological cells such as hereditary elliptocytes.
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Affiliation(s)
- T Ito
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892
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13
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Fukushima Y, Kon H. A flow EPR study of deformation and orientation characteristics of erythrocyte ghosts: effects of lysing and resealing conditions. J Membr Biol 1988; 104:265-73. [PMID: 3210224 DOI: 10.1007/bf01872328] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The effects of various conditions in lysing and resealing the red cell membrane on the degree of ghost deformation and orientation in flow are investigated using the flow EPR and spin-label method. The relatively low deformability of the standard ghost, which is lysed and resealed, respectively, in hypotonic and isotonic NaCl-Tris buffer, is markedly enhanced by the presence of Mg-ATP, chlorpromazine, or Ca2+ ion during resealing. The effect is concentration dependent, and there is an optimal level for each treatment. Chlorpromazine and Ca2+ are also effective when added to the resealed ghosts. Mg2+ ion shows an opposite effect reducing the ghost deformability in flow at all concentrations. An isotonic lysis in NH4HCO3 solution with less osmotic stress substantially raises ghost deformability above that of the standard ghosts. These results are interpreted on the basis of a misalignment between the bilayer leaflets that is probably brought about during hypotonic lysis and its recovery to the nearly normal bilayer state by the agents used during or after resealing. The novel finding of deformability enhancing effect of calcium is assumed to be caused by the electrostatic expansion of the inner layer relative to the outer leaflet. The explanations are supported by the resealed ghost shapes observed before and after the treatments; shape recovery from the monoconcave spheroid toward biconcave discoid is observed in most cases concomitantly with improvements of flow characteristics.
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Affiliation(s)
- Y Fukushima
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892
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Müller E, Hegewald H, Jaroszewicz K, Cumme GA, Hoppe H, Frunder H. Turnover of phosphomonoester groups and compartmentation of polyphosphoinositides in human erythrocytes. Biochem J 1986; 235:775-83. [PMID: 3019307 PMCID: PMC1146755 DOI: 10.1042/bj2350775] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The turnover of phosphomonoester groups of phosphatidylinositol 4-phosphate (PtdIns4P) and phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] was investigated in human erythrocytes by short-term labelling with [32P]Pi. The procedure applied ensured a quantitative extraction of erythrocyte polyphosphoinositides as well as their reliable separation for the determinations of pool sizes and specific radioactivities. The pool sizes of phosphatidylinositol (PtdIns), PtdIns4P and PtdIns(4,5)P2 are 25, 11 and 44 nmol/ml of cells respectively. Under steady-state conditions, the phosphorylation fluxes from [gamma-32P]ATP into PtdIns4P and PtdIns(4,5)P2 are in the ranges 14-22 and 46-94 nmol X h-1 X ml of cells-1 respectively. Only 25-60% of total PtdIns4P and 6-10% of total PtdIns(4,5)P2 take part in the rapid tracer exchange, i.e. are compartmentalized. In isolated erythrocyte ghosts, the turnover of PtdIns4P approximately corresponds to that in intact erythrocytes, although any compartmentation can be excluded in this preparation. Under the conditions of incubation employed, the turnover of PtdIns(4,5)P2 is more than one order of magnitude smaller in isolated ghosts than that obtained for intact erythrocytes.
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Rubinacci A, Fuller B, Wuytack F, De Loecker W. Ca2+ transport and permeability in inside-out red cell membrane vesicles after freezing. Cryobiology 1986; 23:134-40. [PMID: 3698642 DOI: 10.1016/0011-2240(86)90004-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
To evaluate the effects of freezing and thawing on Ca2+ transport and permeability, inside-out red cell membrane vesicles (IORCMV) are examined. Exposure to the cryoprotectant Me2SO as well as different cooling regimes on unprotected and cryoprotected vesicles do not affect the membrane Ca2+ transport. However, freezing and thawing increase the membrane permeability to sucrose.
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Nash GB, Tran-Son-Tay R, Meiselman HJ. Influence of preparative procedures on the membrane viscoelasticity of human red cell ghosts. BIOCHIMICA ET BIOPHYSICA ACTA 1986; 855:105-14. [PMID: 3942734 DOI: 10.1016/0005-2736(86)90194-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The effects of systematic variations in the preparative procedures on the membrane viscoelastic properties of resealed human red blood cell ghosts have been investigated. Ghosts, prepared by hypotonic lysis at 0 degrees C and resealing at 37 degrees C, were subjected to: measurement of the time constant for extensional recovery (tc); measurement of the membrane shear elastic modulus (mu) via three separate techniques; determination of the membrane viscosity (eta m) via a cone-plate Rheoscope. Membrane viscosity was also determined as eta m = mu X tc. Compared to intact cells, ghosts had shorter tc, regardless of their residual hemoglobin concentration (up to 21.6 g/dl). However, prolonged exposure to hypotonic media did increase their recovery time toward the intact cell value. The shear elastic modulus, as judged by micropipette aspiration of membrane tongues (mu p), was similar for all ghosts and intact cells. This result, taken with the tc data, indicates that ghosts have reduced membrane viscosity. Rheoscopic analysis also showed that eta m was reduced for ghosts, with the degree of reduction (approx. 50%) agreeing well with that estimated by the product mu p X tc. However, flow channel and pipette elongation estimates indicated that the ghost membrane elastic modulus was somewhat elevated compared to intact cells. We conclude that: ghosts have reduced membrane viscosity; ghosts have membrane rigidities close to intact cells, except possibly when the membrane is subjected to very large strains; the reduction in eta m is not directly related to the loss of hemoglobin; prolonged exposure of ghosts to low-ionic strength media increases the membrane viscosity toward its initial cellular level. These data indicate that the mechanical characteristics of ghost membranes can be varied by changing the methods of preparation and thus have potential application to further studies of the structural determinants of red cell membrane viscoelasticity.
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