meiotin-1 gene expression in normal anthers and in anthers exhibiting prematurely condensed chromosomes

We have cloned and sequenced the promoter of a meiotin-1 gene, and have det ermined the precise temporal and spatial pattern of meiotin-1 gene expressi on. The expression of the meiotin-1 gene is controlled in two increments. T he meiotin-1 gene is not expressed in any of the vegetative tissues examine d. Early in microsporogenesis, low levels of meiotin-1 RNA can be detected. At the onset of meiosis, there is a dramatic increase in meiotin-1 RNA lev els in both tapetal and meiotic cells. However, while meiotin-1 RNA is obse rved in both the nucleus and cytoplasm of meiotic cells, it is found only i n the nucleus of the tapetal cells. We have also examined the expression of the meiotin-1 gene in aberrant meiotic nuclei that prematurely condense th eir chromosomes; these nuclei have reduced levels of the meiotin-1 protein. The aberrant nuclei have only the basal level of meiotin-1 RNA; they do no t exhibit the transcriptional induction seen for normal cells at the onset of meiosis. Implications for the function of meiotin-1 in regulating chroma tin condensation, and in coordinating meiotic and tapetal cell activities a re discussed.