Ectopic expression of the Drosophila Bam protein eliminates oogenic germline stem cells

Benjamin Ohlstein, Dennis McKearin

Research output: Contribution to journalArticlepeer-review

201 Scopus citations


The Drosophila germ-cell lineage has emerged as a remarkable system for identifying genes required for changes in cell fate from stem cells into more specialized cells. Previous work indicates that bam expression is necessary for cystoblast differentiation; bam mutant germ cells fail to differentiate, but instead proliferate like stem cells. This paper reports that ectopic expression of bam is sufficient to extinguish stem cell divisions. Heat-induced bam+ expression specifically eliminated oogenic stem cells while somatic stem cell populations were not affected. Together with previous studies of the timing of bam mRNA and protein expression and the state of arrest in bam mutant cells, these data implicate Bam as a direct regulator of the switch from stem cell to cystoblast. Surprisingly, ectopic bam+ had no deleterious consequences for male germline cells suggesting that Bam may regulate somewhat different steps of germ-cell development in oogenesis and spermatogenesis. We discuss a model for how bam+ could direct differentiation based on our data that Bam protein is essential to assemble part of the germcell-specific organelle, the fusome. We propose that fusome biogenesis is an obligate step for cystoblast cell fate and that Bam is the limiting factor for fusome maturation in female germ cells.

Original languageEnglish (US)
Pages (from-to)3651-3662
Number of pages12
Issue number18
StatePublished - 1997


  • Bag-of-marbles protein
  • Bam
  • Differentiation factor
  • Drosophila
  • Ectopic expression
  • Germ cell
  • Stem cell

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology


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