Regulation by Polyamines of Ornithine Decarboxylase Activity and Cell Division in the Unicellular Green Alga Chlamydomonas reinhardtii

Abstract

Polyamines are required for cell growth and cell division in eukaryotic and prokaryotic organisms. In the unicellular green alga Chlamydomonas reinhardtii, biosynthesis of the commonly occurring polyamines (putrescine, spermidine, and spermine) is dependent on the activity of ornithine decarboxylase (ODC, EC 4.1.1.17) catalyzing the formation of putrescine, which is the precursor of the other two polyamines. In synchronized C. reinhardtii cultures, transition to the cell division phase was preceded by a 4-fold increase in ODC activity and a 10-and a 20-fold increase, respectively, in the putrescine and spermidine levels. Spermine, however, could not be detected in C. reinhardtii cells. Exogenous polyamines caused a decrease in ODC activity. Addition of spermine, but not of spermidine or putrescine, abolished the transition to the cell division phase when applied 7 to 8 h after beginning of the light (growth) phase. Most of the cells had already doubled their cell mass after this growth period. The spermine-induced cell cycle arrest could be overcome by subsequent addition of spermidine or putrescine. The conclusion that spermine affects cell division via a decreased spermidine level was corroborated by the findings that spermine caused a decrease in the putrescine and spermidine levels and that cell divisions also could be prevented by inhibitors of S-adenosyl-methionine decarboxylase and spermidine synthase, respectively, added 8 h after beginning of the growth period. Because protein synthesis was not decreased by addition of spermine under our experimental conditions, we conclude that spermidine affects the transition to the cell division phase directly rather than via protein biosynthesis.

Melatonin reduces ultraviolet-B induced cell damages and polyamine levels in human skin fibroblasts in culture

“…Polyamines are present in living cells and play a pivotal role in cellular growth and developmental process (Theiss et al, 2002). The naturally occurring polyamines in mammamlian cells are putrescine, spermidine, and spermine (Megosh et al, 2002).…”

“…Total RNA (20 µg) was fractionated by 1% agarose gel electrophoresis (85 V, 5 h) after denaturating the samples with formaldehyde and formamide (Wahl et al, 1979). RNA transcripts obtained were transferred to the charged nylon filter (Zetaprobe, BioRad, CA) in 20×SSC overnight at 4 o C (Theiss et al, 2002). The filters was prehybridized for 12-18 h at 42 o C with prehybridization mixture (50% formamide, 0.1% SDS, 3×SSC, 1×Denhart's solution, 50 g/ml ss-DNA) and hybridized with [ 32 P]-labeled cDNA by nick translation at 42 o C for 24 to 36 h. Following hybridization, the filters were washed and autoradiography was performed.…”

Seaweed reproductive biology: environmental and genetic controls

“…Variation in the expression of GiODC was observed during cystocarp development with levels reduced in fertile tissue (García-Jiménez et al 2009). Ornithine decarboxylase has been characterized in several other algae (including Chlamydomonas, Theiss et al 2002) where it is involved in cell growth and cell division.…”

Bacterial and Plant Signal Integration via D3-Type Cyclins Enhances Symptom Development in the Arabidopsis-Rhodococcus fasciansInteraction

“…Diamines and polyamines are ubiquitously present in all living organisms, but in plants, they occur predominantly in young, actively growing tissues (Theiss et al, 2002). Polyamines are aliphatic polycations whose structure allows the interaction with DNA, RNA, proteins, and phospholipids.…”