passages.id: split_1_test_3457_passage
passages.type: progene_text
passages.text: The discovery that spoIVB is a forespore - expressed gene suggests that the spoIVB gene product , or a developmental event under its control , triggers the processing of pro - sigma K and thereby mediates the coupling of sigma K - directed gene expression in the mother cell to sigma G - directed gene expression in the forespore .