Regeneration Spermidine

Inhibitors of DNA synthesis and cell replication are TGF-jl and HPI (= hepatic proliferation inhibitor). Their function is to block the growth-promoting factors once the nominal size of the liver has been reached. The regeneration course is, however, also linked to a complex network of biochemical processes, including the polyamines (putrescine, spermidine and spermine) as well as the precursors of nucleic acids (orotate, thymidine and uridine). (17, 33, 47-49, 55, 56)... 

Aminopropylation The transfer of decarboxylated SAMe is crucial to the synthesis of polyamines (spermine, spermidine, putresdne). Together with ornithine decarboxylase, SAMe determines the synthesis rate of polyamines, which are essential for cell regeneration. At 30 — 60 minutes, the half-fife of SAMe decarboxylase is very short and thus readily adaptable to various metabolic situations. 

D7. Dykstra, W. G., and Herbst, E. J., Spermidine in regenerating liver Relation to rapid synthesis of ribonucleis acid. Science 149, 428 (1965). 

H2. Hannonen, P., Raina, A., and Janne, J., Polyamine synthesis in the regenerating rat liver Stimulation of s-adenosylmethionine decarboxylase, and spermidine and spermine synthases after partial hepatectmny. Biochim. Biophys. Acta 273,... 

Rl. Raina, A., and Hannonen, P., Biosynthesis of spermidine and spermine in regenerating rat liver Some properties of the enzyme systems involved. Acta Chem. Scand. 24, 3061 (1970). 

The release of previously labeled messenger and ribosomal RNA from nuclei has been achieved in vitro without nuclear lysis in presence of dialyzed cytosol and spermidine. The release induced by the cytosol is energy dependent. The release from regenerating liver nuclei in presence of regenerating liver cytosol is twice what it is in presence of normal liver cytosol. It is postulated that the cytosol contains nondialysable factors that modulate the processing and transport of RNA to cytoplasm after transcription of the RNA has taken place [251]. 

Axonal transport of putrescine, spermidine and spermine in normal and regenerating goldfish optic nerves. Brain Res., 130 433-445. 

Experiments have shown that stress does not increase putrescine levels in all plants. Thus, in osmoticaUy stressed tobacco leaves putrescine levels and ADC activity actually decreased, while spermidine and spermine titer increased (Tiburcio et al, 1986b). Since similar responses were also observed in leaves and protoplasts from other species in which protoplasts are competent to divide and regenerate into complete plants we have proposed that this difference in response may account in part for the failure of cereal mesophyll protoplasts to divide in vitro (Tiburcio et al, 1986c). 

---