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The potential of reversed-phase high-performance liquid chromatography for the separation of various ribo and deoxyribo components of nucleic acids containing photohydrates of pyrimidines has been investigated. The chromatographic properties of the modified nucleobases, nucleosides and nucleotides of uracil and cytosine as well as of the dinucleoside monophosphate, ApU, have been studied. Monomers were separated isocratically in pure water and various water-buffer eluents containing methanol at different pH values. Modified and unmodified dinucleoside monophosphates were separated in acetate buffer with a methanol concentration gradient. The modified compounds have shorter retention times and are readily separated from the original ones. Satisfactory resolution has also been obtained for most diastereoisomeric derivatives of the photohydrates.

The fragments of cotton Gossipium hirsutum c.v. 108-f chloroplast genome were cloned in Escherichia coli cells. The cloned psbA and rbcL genes have been selected using the heterologous probes from spinach. The preliminary attempts to clone the complete psbA gene in pUC19 vector failed, probably, due to the toxicity of its product to Escherichia coli cells, and its 5'- and 3'-ends were cloned separately. Reconstruction experiments revealed that while the complete psbA gene was unable to be stably inherited by Escherichia coli cells, its structural part lacking the promoter region could be readily cloned in the bacterial cells.