Dodecamer d-AGATCTAGATCT and a homologous hairpin form triplex in the presence of peptide REWER.

We have designed a dodecamer d-AGATCTAGATCT (RY12) with alternate oligopurines and oligopyrimidines tracts and its homologous 28 bp hairpin oligomer (RY28) that forms a triple helix only in the presence of a pentapeptide REWER. An intermolecular triplex is formed by the single strand invasion of the RY28 duplex by RY12 in the presence of REWER. 5'- oligopurine end of RY12 binds to oligopurine sequence of RY28 in a parallel orientation and its oligopyrimidine stretch then changes strand and adopts an antiparallel orientation with the other strand of the duplex.

Rec A-independent homologous recombination induced by a putative fold-back tetraplex DNA.

We have recently reported that a GC-rich palindromic repeat sequence presumably adopts a stable fold-back tetraplex DNA structure under supercoiling. To establish the biological significance of this structure, we inserted this sequence between two direct repeat sequences, separated by 200 bp, in a plasmid. We then investigated the effect of this sequence on homologous recombination events.

A palindromic repeat sequence adopts a stable fold back structure under supercoiling.

A synthetic deoxyoligonucleotide containing five palindromic repeats of GGATCC self assembles to form a parallel four-stranded structure held together by G-tetrads that shows slower mobility than duplex DNA. This structure is hypersensitive to S1 nuclease and resistant to DMS modification. The same oligonucleotide when cloned in a plasmid forms a different structure under supercoiling that persists stably even in the cleaved out insert.

Isolation, part characterization, immunogenicity, and specificity study of Plasmodium falciparum culture supernatant.

A Plasmodium falciparum malaria blood stage antigen was isolated from in vitro parasite culture supernatant. The chemical composition of the antigen was studied by high-performance thin-layer chromatography, thin-layer chromatography, gas-liquid chromatography, and other chemical methods. Such analysis indicated it to be a glycophospholipid (GPL) and to be composed of xylose, mannose, galactose, and glucose linked to a phospholipid, but no inositol.