Application of the Deoxyribonucleic Acid/Ribonucleic Acid Hybridization Technique in Bdellovibrio as a Model for Studying Ribonucleic Acid Turnover in Host-Parasite Systems

Abstract

The kinetics of host ribonucleic acid (RNA) degradation and its resynthesis into Bdellovibrio -specific polyribonucleotides has been studied. The kinetics of RNA turnover was followed during a one-step synchronous growth cycle of Bdellovibrio growing within 32 PO 4 -labeled Escherichia coli host cells. The species of labeled RNA present at any given time was ascertained through the specificity of the deoxyribonucleic acid (DNA)/RNA hybridization technique. At nearsaturating levels of RNA and at zero time, 7% of the host DNA sequences and only 0.04% of the Bdellovibrio DNA became hybridized with 32 P-labeled host cell RNA (greater than 99% host specific). At the end of the burst, 98% of the labeled RNA sequences were specific for Bdellovibrio DNA. About 74% of the initial labeled host cell RNA became turned over into Bdellovibrio -specific sequences. We provide data indicating that host cell ribosomal RNA is assimilated by Bdellovibrio . Degradation of host cell RNA occurs in a gradual fashion over most of the Bdellovibrio developmental growth cycle. This application of the DNA/RNA hybridization technique and its general concept should be of value in elucidating the kinetics of nucleic acid turnover in other types of host-parasite systems.