Highly conserved and disease-specific patterns of carboxyterminally truncated Abeta peptides 1-37/38/39 in addition to 1-40/42 in Alzheimer's disease and in patients with chronic neuroinflammation

Human lumbar CSF patterns of Abeta peptides were analysed by urea-based beta-amyloid sodium dodecyl sulphate polyacrylamide gel electrophoresis with western immunoblot (Abeta-SDS-PAGE/immunoblot). A highly conserved pattern of carboxyterminally truncated Abeta1-37/38/39 was found in addition to Abeta1-40 and Abeta1-42. Remarkably, Abeta1-38 was present at a higher concentration than Abeta1-42, being the second prominent Abeta peptide species in CSF. Patients with Alzheimer's disease (AD, n = 12) and patients with chronic inflammatory CNS disease (CID, n = 10) were differentiated by unique CSF Abeta peptide patterns from patients with other neuropsychiatric diseases (OND, n = 37). This became evident only when we investigated the amount of Abeta peptides relative to their total Abeta peptide concentration (Abeta1-x%, fractional Abeta peptide pattern), which may reflect disease-specific gamma-secretase activities. Remarkably, patients with AD and CID shared elevated Abeta1-38% values, whereas otherwise the patterns were distinct, allowing separation of AD from CID or OND patients without overlap. The presence of one or two ApoE epsilon4 alleles resulted in an overall reduction of CSF Abeta peptides, which was pronounced for Abeta1-42. The severity of dementia was significantly correlated to the fractional Abeta peptide pattern but not to the absolute Abeta peptide concentrations.     

The expression of mutation sy2 causing nonhomologous synapsis in meiosis of diploid rye Secale cereale L

The cytological expression of spontaneous mutation sy2 isolated from a population of weedy rye was examined. It was demonstrated that the primary defect of meiosis in the mutant plants is nonhomologous synapsis, which occurs simultaneously with the homologous one. An electron microscope study of the synaptonemal complex (SC) at prophase I showed synaptic abnormalities that manifested as "switches" of synapting axial elements to the nonhomologous partner and the formation of foldbacks of lateral SC elements. The sy2 mutants are characterized by one to two such events per meiosis. Nonhomologous synapsis leads to the appearance of univalents at metaphase I (on average 4.16 +/- 0.022 per meiocyte) and multivalents (on average 0.12 +/- 0.007 per meiocyte). The presence of multivalents in 12.0% of meiocytes at metaphase I may result from recombination in ectopic regions of homology. It is suggested that the sy2 mutation impairs a component of the system that limits synapsis in meiocytes to only homologous chromosome pairs.     

Phylogeny of lobose amoebae based on actin and small-subunit ribosomal RNA genes

Lobose amoebae are abundant free-living protists and important pathogenic agents, yet their evolutionary history and position in the universal tree of life are poorly known. Molecular data for lobose amoebae are limited to a few species, and all phylogenetic studies published so far lacked representatives of many of their taxonomic groups. Here we analyze actin and small-subunit ribosomal RNA (SSU rRNA) gene sequences of a broad taxon sampling of naked, lobose amoebae. Our results support the existence of a monophyletic Amoebozoa clade, which comprises all lobose amoebae examined so far, the amitochondriate pelobionts and entamoebids, and the slime molds. Both actin and SSU rRNA phylogenies distinguish two well-defined clades of amoebae, the "Gymnamoebia sensu stricto" and the Archamoebae (pelobionts + entamoebids), and one weakly supported and ill-resolved group comprising some naked, lobose amoebae and the Mycetozoa.     

DNA slows dissociation of progesterone receptor-steroid ligand complexes

Steroid ligands are known to affect the interactions of their respective receptors with DNA. In the present study, the possibility of DNA interference in progesterone receptor-ligand interactions was investigated. An oligonucleotide containing a hormone response element (HRE) was shown to decrease the dissociation rate of complexes of [3H]progesterone or [3H]16alpha,17alpha-cycloalkanoprogesterones with PRs from rabbit and rat uterine cytosol. The extent to which the oligonucleotide affected the dissociation constant varied from about 4- to 1.5-fold depending on the ligand structure and was ranked in the following order: progesterone>16alpha,17alpha-cyclopropanoprogesterone approximately 16alpha,17alpha-cyclopentanoprogesterone>/=16alpha,17alpha-cyclohex-2'-enoprogesterone approximately 6alpha-methyl-16alpha,17alpha-cyclohexanoprogesterone>/=16alpha,17alpha-cyclohexanoprogesterone. The control oligonucleotide lacking HRE had a weak effect, if any, on the dissociation kinetics. No influence of the HRE-containing oligonucleotide on the equilibrium binding of ligands to PR was observed. The results suggest that the DNA partner affects binding of PR to its ligand.     

Modeling heterochromatin regions in transgenic mice

Transgenic mice carrying bovine satellite DNA IV were obtained. The size of the transgene integrated into the mouse genome was approximately 390 kb (about 100 transgene copies) as determined by a semiquantitative PCR. Restriction analysis with isoschizomeric restrictases HpaII and MspI, showed that the alien DNA was methylated. In the genome of a transgenic founder male, two integration sites for satellite DNA IV were revealed by in situ hybridization and in situ PCR. These sites are situated on two different chromosomes: in pericentromeric heterochromatin and within a chromosomal arm. In transgenic mice, de novo formation of heterochromatin regions (C-block and the CMA3 disk within the centromeric heterochromatin of another chromosome) was revealed by C-banding and staining with chromomycin A3. This formation is not characteristic of mice, because their chromosomes normally contain no interstitial C-blocks or sequences intensely stained by chromomycin A3.     

Mechanism of effect of extracellular pH on L-type Ca(2+) channel currents in human mesenteric arterial cells

Extracellular pH (pH(o)) influences vasoconstriction partly by modulating Ca(2+) influx through voltage-gated Ca(2+) channels in the vasculature. The mechanism of this effect of pH(o) is, however, controversial. Using the whole cell voltage-clamp technique, we examined the influence of pH(o) on L-type Ca(2+) channel currents in isolated human mesenteric arterial myocytes. Acidification to pH 6.2 and alkalinization to 8.2 from 7.2 decreased by approximately 50% and increased by 25-30%, respectively, the peak amplitude of Ca(2+) and Ba(2+) currents (1.5 and 10 mM), with an apparent pK(a) of 6.8. Activation and inactivation of Ca(2+) and Ba(2+) currents were shifted toward positive membrane voltages during acidification and in the opposite direction during alkalinization. The relationship between the current amplitude and shifts in the gating parameters in solutions of different pH(o) conformed closely to that predicted by the Gouy-Chapman model, in which the divalent cation concentration at the outer surface of the membrane varies with the extent to which protons neutralize the membrane surface potential.