Spermidine is rapidly taken up and becomes bound to protein during the very early hours of sea urchin embryogenesis. During the first 6 hr after fertilization of freshly obtained sea urchin eggs (Strongylocentrotus purpuratus), which are incubated in the presence of exogenous [3H]-spermidine, up to 7% of the total cell-associated spermidine appears uniquely as spermidine bound in macromolecular...

BACKGROUND Many gram-negative bacterial pathogens employ Type III secretion systems (T3SS) to inject effector proteins into host cells in infectious processes. METHODOLOGY/PRINCIPAL FINDINGS By screening a transposon mutant library of P. aeruginosa, we found that mutation of spuDEFGH, which encode a major spermidine uptake system, abolished the expression of the exsCEBA operon that codes for ...

Two naturally occurring polyamines, spermidine and spermine, mimicked the actions of insulin on lipid and glucose metabolism in isolated rat adipocytes. In the concentration range of 0.001 to 0.1 mM, spermidine and spermine suppressed lipolysis and stimulated conversion of glucose to carbon dioxide. Structure-function studies revealed that the insulin-mimicking properties of polyamines are depe...

Polyamine composition in an aphid endosymbiotic bacterium, Buchnera sp., was determined by high-performance liquid chromatographic analysis. We found that Buchnera contained virtually only a single polyamine, spermidine. The spermidine content of Buchnera was considerably higher in young aphids and tended to decrease with the age of the host. Expression of speD and speE, whose gene products are...

Targeting polyamines of parasitic protozoa in chemotherapy has attracted attention because polyamines might reveal novel drug targets for antiparasite therapies (Müller et al. 2001). The biological function of the triamine spermidine in parasitic protozoa has not been studied in great detail although the results obtained mainly imply three different functions, i.e., cell proliferation, cell dif...

Putrescine, spermidine, and spermine are a group of small organic cations, collectively known as polyamines. They are present in all living cells, and their levels are generally increased in tumor cells. Progesterone receptor is a gene-regulatory protein that plays a major role in gestation and in hormonal responsiveness of breast cancer. We studied the effects of putrescine, spermidine, 2 lowe...

Polyamines are small poly-cations essential for all cellular life. The main polyamines present in metazoans are putrescine, spermidine and spermine. Their exact functions are still largely unclear; however, they are involved in a wide variety of processes affecting cell growth, proliferation, apoptosis and aging. Here we identify idefix, a mutation in the zebrafish gene encoding the enzyme sper...

The polyamines putrescine, spermidine, and spermine have been implicated in the regulation of both proliferation and differ entiation. Spermidine is required for DNA replication, and the intracellular depletion of this polyamine can be used to distinguish cellular events related to proliferation. We have demonstrated previously that depletion of intracellular spermidine results in cytostasis of...

The polyamines putrescine, spermidine, and spermine have been implicated in the regulation of both proliferation and differentiation. Spermidine is required for DNA replication, and the intracellular depletion of this polyamine can be used to distinguish cellular events related to proliferation. We have demonstrated previously that depletion of intracellular spermidine results in cytostasis of ...

BACKGROUND Spermidine, a naturally occurring polyamine, has recently emerged as exhibiting anti-aging properties. Its supplementation increases lifespan and resistance to stress, and decreases the occurrence of age-related pathology and loss of locomotor ability. Its mechanisms of action are just beginning to be understood. OBJECTIVES An up-to-date overview of the so far identified mechanisms...