Half-lives of oat mRNAs in vivo and in a polysome-based in-vitro system

Abstract

Abstract.We have used a cell-free polysome-based invitro mRNA-degradation system to investigate the halflives of plant cell mRNAs. In order to establish the fidelity of the in-vitro system, we used cordycepin to determine the in-vivo half-lives of 13-tubulin and actin mRNAs in the primary leaves of 4-d-old etiolated oat (Arena sativa L.) seedlings. The in-vitro rank order of half-lives for phytochrome A (45 min), 13-tubulin (105 min), and actin (220 min) mRNAs mimicked the in-vivo rank order. A pulse of red light given to excised etiolated primary leaves caused an in-vivo reduction in the half-life of 13-tubulin mRNA. The selectivity of the polysomebased system was further demonstrated by the decrease in the half-life of [3-tubulin mRNA (from 105 min to 60 min) induced by a pulse of red light given to the etiolated oat seedlings prior to isolation of polysomes. Red light did not affect the apparent half-lives of phytochrome A or actin mRNAs.

Fungal Elicitor-Induced Bean Proline-Rich Protein mRNA Down-Regulation Is Due to Destabilization That Is Transcription and Translation Dependent.

“…We showed that elicitor treatment decreased the P-tubulin mRNA half-life from -3 to -1 hr. The P-tubulin mRNA half-life in etiolated oat leaves was shown to be about 1.5 hr (Byrne et al, 1993). In a numberof mammalian cell cultures, a-tubulin and P-tubulin mRNA half-lives are 1 to 2 hr, and these mRNAs are destabilized by high levels of tubulin heterodimers (Cleveland et al, 1981;Pachter et ai., 1987;Gay et al, 1989).…”

“…Within -0.5 0 I 2 4 6 8 hr 3 hr, the mRNA level decreased to ~6% of the original level, indicating an apparent half-life of ~45 min during the rapid loss. Because transcription is ongoing in these elicited cells, the mRNA degradation kinetics provide an apparent half-life that represents the upper limit of the actual half-life (Belanger et al, 1986;Byrne et al, 1993). To directly evaluate whether the half-life of PvPRPI mRNA decreases in elicited cells, cells were pretreated with actinomycin D to block transcription and then treated with water or elicitor; the decay kinetics of the PvPRPI mRNA were monitored by RNA gel blot analysis ( Figures 3A and 4A).…”

“…The slope is loglo(NJN)/t, where No is the initial amount of mRNA, N is the amount of mRNA at time t, and tis the elapsed time. Under conditions of ongoing transcription, the apparent tth was estimated from mRNA degradation kinetics that defines the upper limit of the turnover rate (Belanger et al, 1986;Byrne et al, 1993).…”

RNase Activities Are Reduced Concomitantly with Conservation of Total Cellular RNA and Ribosomes in O2-Deprived Seedling Roots of Maize

“…Progress has been made in the identification of nucleotide sequences that target mRNAs for rapid degradation (for reviews, see Green, 1993Green, ,1994Abler and Green, 1996), and the description of the processes of decay of specific mRNAs in vivo (Thompson et al, 1992;Higgs and Colbert, 1994) and in vitro in plants (Byrne et al, 1993;Tanzer and Meagher, 1994). Specific mRNAs are destabilized by plant growth regulators and externa1 stimuli such as heat shock, funga1 elicitors, SUC starvation, and light (for review, see Abler and Green, 1996).…”

Iron regulatory elements (IREs): a family of mRNA non-coding sequences

“…In contrast with the RB/Ts-IREs of ferritin and eALAS mRNAs, there are no cell-free extracts currently available in which to study IRE-dependent mRNA stabilization. However, the conditions recently developed to study plant mRNA stability in vitro (Byrne et al, 1993) or c-myc mRNA half-life in vitro (Herrick and Ross, 1994) may be useful for studying TfR mRNAs as well.…”