• bioluminescence;
  • circadian rhythms;
  • Gonyaulax polyedra;
  • in situ hybridization;
  • Pyrrophyta


Radiolabeled RNA transcripts from a cDNA clone of Gonyaulax polyedra Stein luciferin-binding protein (a protein involved in bioluminescence and which increases intracellularly at night) were synthesized in an in vitro transcription assay and hybridized to fixed, thin sections of Gonyaulax cells in both day and night phases. When visualized under dark-field microscopy, probes, which were complementary in sequence (anti-sense probes) to the luciferin-binding protein mRNA, bound to cell sections and revealed a dense, even distribution of photographic silver grains over the cytoplasm, with more intense labeling in night phase cells. Control probes, consisting of the identical sequence as the cellular mRNA (sense probe), revealed little specific labeling in day and night cells. This suggests that cellular levels of luciferin-binding protein mRNA are higher in night phase cells, which is in contrast to recent biochemical findings that the mRNA levels are constant throughout the day and night. This new data is compared with the previous work, and the utility and limitations of the in situ hybridization technique in analyzing message distribution and abundance is discussed.