FLUORESCENTLY-LABELED OLIGONUCLEOTIDE PROBES CAN BE USED TO IDENTIFY PROTISTAN FOOD VACUOLE CONTENTS

In situ hybridization using fluorescent oligonucleotide probes complem entary to unique regions of 16S rRNA molecules provides a way of ident ifying the food vacuole contents of bactivorous protists. Laboratory e xperiments with Tetrahymena showed rRNAs in food vacuoles are degraded slowly enough to permit their use as hybridization targets for such p robes. A probe specific for a hypervariable region of the small subuni t rRNA of an unnamed proteobacterium abundant in a local rake was then synthesized. It was used to probe the food vacuoles of the ciliates p resent in fixed water samples collected from the same lake. The vacuol es of several filter-feeding ciliates bound the probe, indicating that such probes can be used to identify the food vacuole contents of cili ates collected from natural samples.