The quantitative and reversible compaction of open circular plasmid DNA (7676 bp) into toroids containing one to 19 molecules by sequential treatment with spermine and an excess of uranyl acetate is reported. The toroidal DNA structure was proven by cryoelectron microscopy. Linearized and supercoiled variants of the DNA also gave toroids under these conditions, but yields were significantly lower. In the presence of spermine alone no toroids were found. Open circular plasmid B-DNA helix was converted into the C-type helical form upon compaction as was shown by CD spectroscopy (negative peak at 255 nm) and electron microscopy (1.8-nm interduplex distance instead of 2.9 nm). Addition of uranyl salt to the DNA−spermine complexes resulted in the formation of netlike assemblies which further compacted to give toroids. A model containing a hexagonal arrangement of DNA strands with extensive strand crossings is proposed. Curvature and thus toroid formation is thought to be induced by the hydrophobic DNA coating of spermine methylene groups.

A cDNA clone of the mRNA coding for the human complement system control protein Factor I has been isolated. The predicted amino acid sequence obtained from the DNA sequence demonstrates a protein consisting of a heavy chain (Mr 35,400) linked to a light chain (Mr 27,600), both of which contain three sites for N-linked glycosylation. The light chain has clear homology with other serine proteinases, most notably in the region of the catalytically active and structurally important amino acids and shares some of the features characteristic of the plasminogen activators. The heavy chain has a clear 'mosaic' nature typical of the plasma serine proteinases; in particular it contains class A and class B LDL (low-density lipoprotein) receptor repeats with conserved cysteine residues similar to those found in other complement proteins.

We have quantified the effects of the regiochemical distribution of positive charges along the polyamine moiety in lipopolyamines for DNA molecular recognition. High affinity binding leads to charge neutralisation, DNA condensation and ultimately to lipofection. Binding affinities for calf thymus DNA were determined using an ethidium bromide displacement assay and condensation was detected by changes in turbidity using light scattering. The in vitro transfection competence of cholesterol polyamine carbamates was measured in CHO cells. In the design of DNA condensing and transfecting agents for non-viral gene therapy, the interrelationship of ammonium ions, not just their number, must be considered.z 1999 Federation of European Biochemical Societies.

This paper investigates whether people with Williams syndrome (WS) have prosodic impairments affecting their expression and comprehension of four main uses of intonation. Two adolescent males with WS were assessed using the PEPS-C battery, which considers prosodic abilities within a psycholinguistic framework, assessing prosodic form and function in both the input and output domains. The performances of the subjects with WS were compared with control data for age and language-comprehension matched children. The results revealed significant prosodic impairment affecting all areas of the profile. Crucially, however, different profiles of strengths and weaknesses were revealed for the two subjects. The results support the growing view that WS is a heterogeneous population in terms of linguistic abilities.

Polyaminhaltige Bolaamphiphile binden an DNA in einer Weise, dass diese eine kompakte, wohldefinierte Faltung einnimmt. Die Aggregate widerstehen dem Abbau durch Nucleasen, und sie können zur effizienten Transfektion von Eierstockzellen aus Hamstern dienen. Durch den Einbau eines geringen Prozentsatzes eines Polyethylen‐Bolaamphiphils wird die unspezifische Aufnahme verringert; die zielgerichtete Transfektion menschlicher T‐Zelllinien wurde demonstriert anhand eines Anti‐CD3‐Antikörper/Bolaamphiphil‐Konjugats, das zu 0.004 % in die supramolekulare Anordnung eingebaut wurde.