Unusual Polymorphism Research Articles

Parasexual analysis of human pepsinogen molecular heterogeneity.

Pepsinogens (PGA) are the inactive precursors of pepsin, the major acid protease found in the stomach. Highly polymorphic variation of these proteins has been demonstrated in several populations, and comparison of the DNA restriction fragment patterns obtained from informative pepsinogen phenotypes suggest that the polymorphism results from chromosomal haplotypes containing variable numbers of pepsinogen genes. In order to isolate the three most common PGA haplotypes (A, B, and C) and to unambiguously demonstrate their relationship to the observed protein heterogeneity, we constructed mouse X human somatic cell hybrids from individuals heterozygous for PGA and INS (insulin). Here, we describe analysis of hybrid cell lines that segregated human chromosomes containing the PGA genes and thereby provided for the parasexual discrimination of the different haplotypes on chromosome 11 determining the corresponding heterozygous phenotypes. These studies demonstrate that the A, B, and C haplotypes contain three, two, and one PGA genes, respectively. This unusual polymorphism of genomic DNA encoding very similar proteins probably reflects recent evolution by gene duplication.

Analysis of C3b/C4b receptor (CR1) polymorphic variants by tryptic peptide mapping

The human C3b/C4b receptor (CR1) binds the major activation and opsonic fragments of the third (C3) and fourth (C4) components of complement. CR1 is a single chain integral membrane glycoprotein widely distributed on peripheral blood cells. Four codominantly inherited allelic variants with M rs of 160,000, 190,000, 220,000 and 250,000 have been described. To address the structural basis for this unusual polymorphism, CR1 from donors expressing three of the four allelic variants was purified from surface labeled ( 125I) erythrocytes by iC3-Sepharose affinity chromatography and the variants compared by tryptic peptide mapping (TPM). The TPMs of each variant contained the same major peaks and minor peak areas and were nearly identical to one another. Tryptic peptide mappings of the 190,000 M r erythrocyte CR1, which was purified prior to iodination, were similar to those derived from surface iodinated CR1. The TPMs of erythrocyte and granulocyte CR1 from the same donor differed by a single peak of increased prominence in the granulocyte map. These results indicate a conservation in amino acid sequence for those peptides detected. In view of these data and those of other studies of the structure and genetics of CR1 and related proteins, it is suggested in this paper that the allelic variation relates to CR1, being composed of repeating amino acid sequences.

Polymorphism of the C3b/C4b receptor (CR1): characterization of a fourth allele.

The receptor for C3b/C4b (C3bR or CR1) has an unusual polymorphism in which three codominant alleles determine variants with a large difference in Mr (160,000, 190,000, or 220,000). We found an individual who has, in addition to the common 190,000 Mr molecule, a C3bR whose Mr is 250,000. In this proband and in some members of his family, this novel heterozygous phenotype can be isolated from 125I surface-labeled cells by iC3 or iC4 affinity chromatography or by immunoprecipitation with the use of polyclonal or monoclonal anti-C3bR. Relative to the 190,000 Mr C3bR, E from individuals in this family have 20 to 30% of the total receptor counts in the 250,000 Mr C3bR. However, on C3bR-bearing leukocytes there is a much larger amount of the 250,000 Mr C3bR (approximately 60%) relative to the 190,000 Mr C3bR. Similar to the other three C3bR variants, the Mr is 5,000 greater on polymorphonuclear cells than on E, and treatment of this new C3bR with endoglycosidase F decreases its Mr by approximately 10,000. Therefore, because this variant is inherited and has structural and functional similarities to the other three C3bR, we conclude that this 250,000 Mr CR1 probably represents a fourth allele.

An unusual photo-induced conformational polymorphism: a crystallographic study of bis(p-methoxy)-trans-stilbene

A novel example of a photo-induced single-crystal to single-crystal phase transformation is described for title compound; the accompanying change in molecular conformation is rationalised in terms of an intermediate excimeric state.

Characterization of an unusual DNA length polymorphism 5' to the human antithrombin III gene.

Nucleotide sequence analysis revealed that a DNA length polymorphism 5' to the human antithrombin III gene is due to the presence of 32bp or 108bp nonhomologous nucleotide sequences (variable segments) 345bp upstream from the translation initiation codon. Sequences at the 3' borders of both variable segments can form intrastrand inverted repeat structures with sequences further downstream. An inverted repeat is also found immediately 5' to the site where the variable segments are located. Thus, cruciform structures may form flanking the variable segments of both alleles of this DNA length polymorphism. DNA secondary structure may be detected with single strand specific nucleases. S1 nuclease sensitive sites were mapped in recombinant plasmids containing the cloned alleles of the ATIII length polymorphism. The site most sensitive to S1 is located upstream from the variable segments in an AT-rich segment flanked by 6bp direct repeats. A region of lesser nuclease sensitivity was also observed in the AT-rich loops formed between the inverted repeats 5' to the variable segments.

Die Kristallstruktur von β-Li3VF6

Abstract The crystal structure of the metastable high temperature β-phase of Li3VF6 has been determined from 1404 independent reflections (R = 0.035). The space group is C2/c, Z = 12, a = 1440.5(6)pm, b = 868.8(3)pm, c = 1008.2(4) pm, β = 95.84(3)°, dc = 2.949 g cm−3, dm = 2.94 g cm−3. The hitherto unknown β-form of Li3CrF6 has been prepared using a mineralisator [lattice constants: a = 1438.2(5) pm, b = 859.4(3) pm, c = 1001.1(2)pm, β = 94.81(2)°]. In contrast to the cryolithe related room temperature α-form β-Li3VF6 represents a new structure type. While the V-atoms and 7/9 of the Li-atoms have octahedral coordination, the remaining 2/9 of the Li-atoms show a distorted tetrahedral environment and form binuclear [Li2F6]-groups. The octahedra are linked to units of one [VF6] and two [LiF6] groups having one common vertex and sharing three edges like the octahedra in some heteropoly anions. These units form a 3-dimensional network by additional edge and corner sharing with each other and the [Li2F6]-groups. The unusual polymorphism of the isotypic Li3MF6 compounds (M = Al, Ga, Cr, Fe, V, Ti) is discussed on the base of these new results.

Caste polymorphism inHarpagoxenus canadensis M. R. Smith (Hym. Formicidae)

The European slave-making antHarpagoxenus sublaevis has an unusual female polymorphism. In addition to ordinary workers, there are two kinds of reproductive females, the very rare full queens and the much more common ergatoid (i. e. workerlike) queens. A genetic mechanism is responsible for the development of larvae into either ergatoid or full queens. Sixty-one colonies of the closely related North American speciesHarpagotenus canadensis were collected from several localities in the provinces of Ontario and Quebec, Canada, and a total of 241 workers, 30 intermorphs, and 26 dealate full queens were dissected in order to discover whether a similar polymorphism occurs in this species. However,H. canadensis was found to have an essentialy normal polymorphism. All the fecundated reproductive females that we found were dealate full queens. A spermatheca, which constitutes the only significant difference between ergatoid queens and workers inH. sublaevis, is absent in all workers and intermorphs ofH. canadensis. In addition, we found that colonies ofH. canadensis are monogynous (likeH. sublaevis). However, minority of workers and intermorphs lay eggs even in queenright colonies. The average number of ovarioles is much lower inH. canadansis workers than in those ofH. sublaevis; but, in both species, it varies over about the same range (table IV). In this respect,H. canadensis workers resemble more closely the workers of the host species. The number of Malpighian tubules is five in both the reproductive females and workers. The poison gland is about the same size in bothHarpagoxenus species, but the Dufour's gland inH. canadensis is considerably smaller than inH. sublaevis. Thus, in several respects,H. canadensis bears a closer resemblance to the common host genusLeptothorax (subgenusMychothorax) thanH. sublaevis does.

Inherited unusual polymorphism of nucleolar organizer region of choromosome 22

Inherited unusual polymorphism of nucleolar organizer region of choromosome 22

An unusual caste polymorphism of the sternal gland and its trail pheromone production in the termiteTrinervitermes bettonianus

The sternal glands of the various castes inT. bettonianus differ drastically in size and potential trail-laying activity. In soldiers they are almost vestigial and without evident function. In workers they are normal in size compared with those of other termite species, and their secretion is employed for communicative trails. In the imagines, however, they are extremely large and contain enormous quantities of trail pheromone. This or other pheromones secreted by the sternal gland are functionally involved in courtship behaviour.

Polymorphism and Molecular Dynamics in Beryllium Oxyacetate, Be4O(CH3COO)6

The unusual polymorphism of beryllium oxyacetate, Be4O(CH3COO)6, was investigated by means of pulsed NMR between −196°C and the melting point (286.7°C). In the α modification of this substance, fast methyl group reorientation takes place, and the spin-spin and spin-lattice relaxation times proved to be insensitive to the presence of the reported second or higher order phase transitions. The onset of a relatively slow motion with an activation energy of 15.5± 0.8 kcal/mole was found above the first order phase transition at ∼148°C, and this motion is likely to be over-all molecular tumbling motion. The transition from a high symmetry cubic phase to a lower symmetry orthorhombic structure on raising the temperature is discussed. No self-diffusion is present up to the melting point. The high temperature γ phase of beryllium oxyacetate does not seem to be a plastic crystal as was proposed previously. In light of our results, the isotropic optical property by itself is of questionable usefulness as a criterion for plasticity of molecular crystals. Unusual behavior of the spin-lattice relaxation between −20°C and −196°C was determined, and the possibility that additional phase transitions are present has to be further studied.