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  • 1
    Electronic Resource
    Electronic Resource
    Can we predict the mating pattern ofDrosophila females from the sperm length distribution in males? (1991)
    Springer
    Cellular and molecular life sciences 47 (1991), S. 111-114 
    Details
    ISSN: 1420-9071
    Keywords: Drosophila ; repeat matings ; polyandrous pattern diversity ; sperm length
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In order to test the validity of the prediction of the mating pattern of females from the sperm length distribution in males, three species ofDrosophila were analysed. Males in the three species are equally polygynous but females differ in the level of polyandry. A ‘low recurrence polyandry’ is observed in the sperm dimorphic speciesD. affinis while a ‘high recurrence polyandry’ is observed in the sperm monomorphic speciesD. latifasciaeformis andD. littoralis. These results are consistent with the hypothesis proposed previously that sperm dimorphism in males can only be maintained by a selective alternative in females (i.e. facultative female polygamy), whereas a stricter mating system (e.g., ‘obligatory’ polyandry) should only result in sperm monomorphism irrespective of the absolute value of sperm length.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02041270
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  • 2
    Electronic Resource
    Electronic Resource
    Spectrin αIIa variant in dominant and non-dominant spherocytosis (1993)
    Springer
    Human genetics 〈Berlin〉 92 (1993), S. 153-156 
    Details
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Several polymorphic mutations are located on the spectrin α-chain; among these the variant termed αIIa is characterized by an acid shift in the isoelectric point of the tryptic digest peptides 46 kDa and 35 kDa. In this variant a single amino acid substitution (alanine to aspartic acid) occured at position 972 of the spectrin α-chain due to a point mutation (GCT to GAT) in the DNA. This variant, which seemed very rare in normal people, could be related to the recessive form of hereditary spherocytosis (HS) and could be absent in the dominant form of the disease. We have studied the αIIa variant by denaturing electrophoresis of the spectrin tryptic digest peptides from 179 subjects: 46 controls, 78 patients with dominant (d) or non dominant (nd) HS and 55 relatives of the patients. The confirmation of the results was obtained at the DNA level in 41 subjects. The frequency of the chromosome bearing the αIIa mutation was 7.6% in controls and higher (about 12–14%) in members of families with dHS as well ndHS. However, the family trees clearly showed that the mutation and the HS disease gene(s) were located on different chromosomes and inherited independently from each other. Furthermore, our study allows the conclusion that in most (if not all) cases of dHS, the αIIa the variant is not the cause, is not a marker, and does not influence the phenotypic expression of the disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219683
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  • 3
    Electronic Resource
    Electronic Resource
    Spectrin αIIa variant in dominant and non-dominant spherocytosis (1994)
    Springer
    Human genetics 〈Berlin〉 93 (1994), S. 614-614 
    Details
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00202839
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  • 4
    Electronic Resource
    Electronic Resource
    Murine H-2Dd-reactive monoclonal antibodies recognize shared antigenic determinant(s) on human HLA-B7 or HLA-B27 molecules or both (1983)
    Springer
    Immunogenetics 17 (1983), S. 357-370 
    Details
    ISSN: 1432-1211
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have evaluated the serological relationships between the murine H-2Dd and human HLA molecules using four H-2Dd-reactive monoclonal antibodies (mAbs) produced in the A.BY (KbIbDb) anti-A.TL (KsIkDd) combination. In the mouse, these reagents exhibited three distinct reactivity patterns: Dd, Ks, and H-2u (mAb 81.L); Dd, H-2p, and H-2u (mAb 81.R); and Dd, Kd, H-2p, H-2u, and H-2v (mAbs 97.G and 97.H). Sequential immunoprecipitation and cross-competitive mAb binding experiments revealed that these mAbs recognized determinants in two spatially distinct polymorphic domains on the H-2Dd molecule of B10.A(5R) cells (defined by mAbs 81.L and 81.R, 97.H, and 97.G, respectively). MAbs 81.R, 97.G, and 97.H, but not 81.L, also defined an HLA-linked polymorphism in the human, the main characteristics of which can be summarized as follows: (i) on B lymphoblastoid cell lines, mAbs 81.R and 97.H bound to cells expressing the HLA-B7, HL-B27 or -Bw40 cross-reacting specificities, (ii) on peripheral blood lymphocyte (PBL) panel mAb 81.R exerted C dependent cytotoxicity to 118 of 400 cells tested, including almost all HLA-B7 or HLA-B27 cells or both (r: 0.952), (iii) the expression of the 81.R. cross-reacting determinant segregated in an informative family with the parental haplotype carrying the HLA-B7 allele, and (iv) mAbs 81.R, 97.G, and 97.H recognized topologically related determinants on the same class I molecule(s) of the human B lymphoblastoid cells JY (HLA-A2,2, -B7,7). These data support the view that some, but not all H-2Dd allotopes have been conserved throughout evolution and are associated in the human with the HLA-B7, -B27 cross-reacting specificities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00372455
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  • 5
    Electronic Resource
    Electronic Resource
    Clonal analysis of B- and T-cell responses to Ia antigens (1981)
    Springer
    Immunogenetics 14 (1981), S. 481-495 
    Details
    ISSN: 1432-1211
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Thirty-five Iak-specific monoclonal alloantibodies, derived from hybridomas constructed by fusion between mouse myeloma and spleen cells from A.TH alloimmune mice (I S anti-I k ), have been used to estimate the allotypic polyporphism of the Ik-gene products. Cross-blocking studies using 17 mAb specific for the I-A molecule indicated that six determinants, which were associated with the conventional specificities Ia.2 and Ia.19, were organized in at least three distinct polymorphic areas of the I-Ak molecules. Similarly, another group of six determinants, which did not correspond to previously described conventional Ia specificities, were found to be topologically heterogeneous. By contrast, the five epitopes associated with the Ia. 1 specificity were clustered into a single region of this molecule. In addition the potentiation of binding observed between mAb specific for topologically distinct epitope regions of the I-Ak molecule, suggested that the latter may undergo conformational changes after binding of a given mAb. A similar analysis of 17 mAb specific for the I-Ek molecule indicated that specificity Ia. 7 of the Eα chain (as defined in this series by eight mAb) was composed of three topologically distinct polymorphic areas, one of which is also spatially related to a complex cluster of eight new determinants of the I-Ek molecule. Finally, one mAb identified a so far undescribed shared determinant of the I-Ak and I-Ek molecules. The present results, which provide a new estimate of the allotypic polymorphism of the Iak antigens, are discussed with regard to their functional, biochemical, and evolutionary implications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00350120
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  • 6
    Electronic Resource
    Electronic Resource
    High resolution proton magnetic resonance of sonicated phospholipids (1985)
    Springer
    European biophysics journal 11 (1985), S. 219-223 
    Details
    ISSN: 1432-1017
    Keywords: Phospholipid vesicles ; 1H-NMR ; spin lattice relaxation time ; spin label
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract We have recorded high resolution proton magnetic resonance spectra of sonicated phospholipid vesicles. The following lipids were used in separate experiments: phosphatidylglycerol, phosphatidylserine, phosphatidylethanolamine, and phosphatidylcholine from egg yolk as well as dimyristoyl phosphatidylcholine. Mixed lipid vesicles were also investigated. Assignments of the peaks associated with the various protons of the different lipids are presented. It is shown that in favorable cases, it is possible to resolve the different phospholipid head groups of mixed lipid samples. Spin lattice relaxation times (T1) of each peak were collected at 500 MHz and 90 MHz. The influence of the addition of a small concentration of spin labeled phospholipid on i) the linewidths ii) the spin lattice relaxation times, was determined. It is shown that nitroxide radicals selectively broaden the peaks associated with the protons localized at a comparable depth of the bilayer. On the other hand, T1 are less selectively perturbed. Potential applicability of 1H-NMR for the investigation of lipid-proton specificity in membranes is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00261998
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  • 7
    Electronic Resource
    Electronic Resource
    Lateral diffusion of erythrocyte phospholipids in model membranes comparison between inner and outer leaflet components (1990)
    Springer
    European biophysics journal 18 (1990), S. 33-41 
    Details
    ISSN: 1432-1017
    Keywords: Phospholipid asymmetry ; Lateral diffusion ; Photobleaching ; Spin-labels ; ESR ; Cholesterol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The physical properties of lipid bilayers with a similar composition to the outer and inner leaflets of the human erythrocyte membrane have been examined in protein-free model systems. The outer leaflet (OL) was represented by a phospholipid mixture containing phosphatidylcholine and sphingomyelin extracted from human erythrocytes, while a mixture of phosphatidylcholine, phosphatidylserine and phosphatidylethanolamine represented the inner leaflet (IL). The ratio of cholesterol to phospholipid was varied in both mixtures. The lateral diffusion coefficient of fluorescent phospholipids diluted in such lipid mixtures was determined by the modulated fringe pattern photobleaching technique. Contrast curves with a single exponential decay, indicative of homogeneous samples, were obtained only for temperatures above 15 °C and for a cholesterol to phospholipid molar ratio below 0.8. The rate of lateral diffusion was approximately five times faster in IL than in OL multilayers, in agreement with former results obtained in human erythrocytes (Morrot et al. 1986). Varying the cholesterol to phospholipid ratio from 0 to 0.8 (mol/mol) enabled us to decrease the diffusion constant by only a factor of approximately 2 for both IL and OL mixtures. The order parameter of a spin-labeled phospholipid was determined in the different systems and found to be systematically smaller in IL mixtures than in OL mixtures. The present study indicates that the difference in lipid diffusivity of the two erythrocyte leaflets may be accounted for solely by a difference in phospholipid composition, and may be independent of cholesterol and protein asymmetry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185418
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  • 8
    Electronic Resource
    Electronic Resource
    2H and 31P NMR study of pentalysine interaction with headgroup deuterated phosphatidylcholine and phosphatidylserine (1988)
    Springer
    European biophysics journal 16 (1988), S. 267-273 
    Details
    ISSN: 1432-1017
    Keywords: Phosphatidylserine ; polylysine ; lipidpeptide interaction ; deuterium NMR ; phosphorus NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The interaction of cationic pentalysine with phospholipid membranes was studied by using phosphorus and deuterium Nuclear Magnetic Resonance (NMR) of headgroup deuterated dimyristoyl phosphatidylcholine (DMPC) and dimyristoyl phosphatidylserine (DMPS). In the absence of pentalysine, some of the deuterium and phosphorus spectra of DMPC/DMPS 5:1 (m:m) membranes gave lineshapes similar to those of partially-oriented bilayers with the planes of the bilayers being parallel to the magnetic field. The deuterium NMR data show that the quadrupolar splittings of the deuterated methylenes of the DMPC headgroup are not affected by adsorption of pentalysine on the PC/PS membranes. By contrast, the pentalysine produces significant changes in the quadrupolar splittings of the negatively charged DMPS headgroup. The results are discussed in relation to previous 2H NMR investigations of phospholipid headgroup perturbations arising from bilayer interaction with cationic molecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00254062
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  • 9
    Electronic Resource
    Electronic Resource
    Biomembrane elastic response to intercalation of amphiphiles (1990)
    Springer
    European biophysics journal 19 (1990), S. 69-72 
    Details
    ISSN: 1432-1017
    Keywords: Elastic membrane ; Bilayer couple hypothesis ; Shape change ; Transverse asymmetry ; Erythrocyte membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract A model of the elastic behavior of a biomembrane in response to intercalation of amphiphiles into the bilayer is developed. This model takes into account the bilayer couple hypothesis (Sheetz and Singer 1974), and assumes that incorporation of amphiphiles into one layer of the membane exerts mechanical work on the elastic biomembrane. The model accounts for an apparent experimental discordance noted by several authors: the variation in area observed upon incorporating amphiphiles is smaller by a factor of about 2 than the variation expected using previous models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185088
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  • 10
    Electronic Resource
    Electronic Resource
    High-resolution 31P-1H two-dimensional Nuclear Magnetic Resonance spectra of unsonicated lipid mixtures spinning at the magic-angle (1996)
    Springer
    European biophysics journal 25 (1996), S. 131-137 
    Details
    ISSN: 1432-1017
    Keywords: Key words Liposome ; Solid-State NMR ; Magic-Angle Spinning ; Lipid-water interaction ; Spin-diffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract For multilamellar suspensions of phospholipids, the 1H and 31P Nuclear Magnetic Resonance (NMR) spectra obtained with magic-angle spinning (MAS) exhibit resolution comparable to that of sonicated vesicles. However, specific lipid head groups cannot be recognized in a lipid mixture using one-dimensional NMR spectroscopy. We show here that the combination of MAS and two-dimensional Heteronuclear Overhauser Effect SpectroscopY (HOESY) reveals magnetic interactions between the phosphate and its neighbouring protons and thus allows the distinction in situ of several lipids in a mixture. The 31P-1H HOESY spectra of suspensions of phosphatidylcholine and phosphatidylglycerol or phosphatidylcholine, phosphatidylethanolamine and sphingomyelin are shown as examples. In the course of these experiments, intramolecular spin-diffusion as well as intermolecular interactions between lipids and water were observed. The technique should enable the investigation of lipid-lipid and lipid-protein interactions, lipid hydration as well as lipid asymmetry in membranes without the use of isotopically labeled lipids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002490050024
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