The zygosity in the human HL-A transplantation system

Summary If by serological methods of tissue typing one antigen only is detected in one or both of the loci LA and 4 of the histocompatibility system HL-A, the question arises whether it is homozygous or heterozygous. The probability thereof is calculated. It depends on the frequency of the known and unknown genes in the HL-A-system. If e.g. the HL-A type of an examinee is 1,3,8 this subject could be homozygous 1,3,8,8 or heterozygous (with an unknown antigen X) 1,3,8,X. The frequencies of homozygous and heterozygous individuals are calculated in all possible combinations of the LA and 4 loci. The results justify always for both the LA-and 4 locus the assumption of heterozygosity, with the one exception that the gene HL-A 2 is under consideration. There the calculations result in a value of 49% for homozygosity (2,2) and 51% for heterozygosity (2,X). Neither alternative is in this case essentially more probable.For transplantations generally heterozygosity can be assumed — with the exception of HL-A 2 — and therefore the minor grade of histocompatibility.National Blood Group Reference Laboratory — WHO (Director: Prof. Dr. P. Speiser)     

Potent dihydroquinolinone dopamine D2 partial agonist/serotonin reuptake inhibitors for the treatment of schizophrenia

A dihydroquinolinone moiety was found to be a potent serotonin reuptake inhibitor pharmacophore when combined with certain amines. This fragment was coupled with selected D₂ ligands to prepare a series of dual acting compounds with attractive in vitro profiles as dopamine D₂ partial agonists and serotonin reuptake inhibitors. Structure–activity studies revealed that the linker plays a key role in contributing to D₂ affinity, function, and SRI activity.     

Nitrate uptake and carbon exudation – do plant roots stimulate or inhibit denitrification?

Plant and Soil - Plant growth affects soil moisture, mineral N and organic C availability in soil, all of which influence denitrification. With increasing plant growth, root exudation may stimulate...     

Production of monoclonal antibodies against surface antigens of spores from arbuscular mycorrhizal fungi by an improved immunization and screening procedure

Monoclonal antibodies (mAbs) were produced against surface antigens of chlamydospores of arbuscular mycorrhizal (AM) fungi by immunizing mice with crushed or complete spores. The intrasplenic approach proved to be superior to the intraperitoneal method of immunization with regard to the amount of antigen required for the immune response. The hybridoma technology was combined with an improved screening procedure, applying an immunogold-silver staining technique to semi-thin sections of spores. In this way, mAbs to surface antigens on the outer wall could be selected. Two mAbs were raised against Glomus etunicatum and G. scintillans spores. Cross-reactivities of the antibodies to other structures of the fungus, to other species of Glomus and to other soil-borne fungi were tested with indirect immunofluorescent labelling. The mAbs did not react with non-AM fungi. One mAb (A5B1) selectively recognized G. etunicatum, another (D12F11) exhibited limited interspecies cross-reactivities. One further mAb (H8F7), which reacted with spores of all AM fungi but not with other fungi, was shown to be specific for Bacillus mycoides. The implications are discussed.     

Polymorphism of glyoxalase I in Vienna.

Phenotype and gene frequencies of the GLO I polymorphism in Vienna are given. No exception to the postulated rule of inheritance could be found in 23 families with 51 children and 132 mother-child pairs. Linkage with the HLA system is confirmed, but no linkage disequilibrium between GLO alleles and HLA-A, B, C genes was detected. The use of the GLO I polymorphism in paternity cases is discussed.     

Von Hippel-Lindau (VHL) disease with pheochromocytoma in the Black Forest region of Germany: evidence for a founder effect

We identified a germline missense mutation at nucleotide 505 (T to C) of the VHL tumor suppressor gene in 14, apparently unrelated, VHL type 2A families from the Black Forest region of Germany. This mutation was previously identified in two VHL 2A families living in Pennsylvania (USA). All affected individuals in the 16 families shared the same VHL haplotype indicating a founder effect. This missense mutation at codon 169 (Tyr to His) would probably cause an alteration in the structure of the putative VHL protein. The association of this distinct mutation with the pheochromocytoma phenotype in VHL may help to elucidate the genetic mechanism of carcinogenesis in this multi tumor cancer syndrome.     

Single amino acid substitutions and deletions that alter the G protein coupling properties of the V2 vasopressin receptor identified in yeast by receptor random mutagenesis

To facilitate structure-function relationship studies of the V2 vasopressin receptor, a prototypical G(s)-coupled receptor, we generated V2 receptor-expressing yeast strains (Saccharomyces cerevisiae) that required arginine vasopressin-dependent receptor/G protein coupling for cell growth. V2 receptors heterologously expressed in yeast were unable to productively interact with the endogenous yeast G protein alpha subunit, Gpa1p, or a mutant Gpa1p subunit containing the C-terminal G alpha(q) sequence (Gq5). In contrast, the V2 receptor efficiently coupled to a Gpa1p/G alpha(s) hybrid subunit containing the C-terminal G alpha(s) sequence (Gs5), indicating that the V2 receptor retained proper G protein coupling selectivity in yeast. To gain insight into the molecular basis underlying the selectivity of V2 receptor/G protein interactions, we used receptor saturation random mutagenesis to generate a yeast library expressing mutant V2 receptors containing mutations within the second intracellular loop. A subsequent yeast genetic screen of about 30,000 mutant receptors yielded four mutant receptors that, in contrast to the wild-type receptor, showed substantial coupling to Gq5. Functional analysis of these mutant receptors, followed by more detailed site-directed mutagenesis studies, indicated that single amino acid substitutions at position Met(145) in the central portion of the second intracellular loop of the V2 receptor had pronounced effects on receptor/G protein coupling selectivity. We also observed that deletion of single amino acids N-terminal of Met(145) led to misfolded receptor proteins, whereas single amino acid deletions C-terminal of Met(145) had no effect on V2 receptor function. These findings highlight the usefulness of combining receptor random mutagenesis and yeast expression technology to study mechanisms governing receptor/G protein coupling selectivity and receptor folding.