RNAi depletion of ALPH1 causes an increase in intact mRNA molecules, but no increase in 5’-3’ decay intermediates.

(A) Experimental design: The endogenous very long and short-lived mRNA Tb427.01.1740 was used as a reporter for mRNA metabolism [55]. Simultaneous probing of the extreme 5’ and 3’ ends with red and green fluorescent single mRNA FISH probes results in yellow, green or red fluorescent mRNA molecules, corresponding to intact mRNAs, mRNAs in 5’-3’ decay and mRNAs in transcription or 3’-5’ decay, respectively. (B) The numbers of yellow, green and red fluorescent spots were quantified from cells after induction of ALPH1 RNAi (0, 24 or 48 hours TET) from at least 130 cells per time-point, for three RNAi clones. Average data are shown; error bars represent the standard deviations between the different RNAi clones. The numbers of the differently coloured spots per total cell are shown (left), but also the numbers of spots in the nucleus (middle) or in the cytoplasm (right). If the centre of a spot was overlapping with the DAPI stained nucleus on a Z-stack projection image, the spot was defined as nuclear, otherwise as cytoplasmic. (C) Representative Z-stack projection images of untreated cells (no TET) and cells after 48 hours of ALPH1 RNAi (48 h TET).