Biosynthesis and metabolism of 1,4-diaminobutane, spermidine, spermine, and related amines.

New aspects of polyamine biosynthesis in eukaryotic organisms.

The early history of polyamine research.

Hydroxycinnamic acid amides in fertile and cytoplasmic male sterile lines of maize

Ornithine decarboxylase activity and polyamine synthesis during kidney hypertrophy.

The fertilized chick egg is a highly organized system with all the properties for a normal differentiation and development. The events during the embryo development are characterized by a large series of complex and definite chemical reactions, all having a temporal sequence and regulated by the trinomial: DNA -+ RNA --+ proteins. This complex biological system is useful in studying the molecular mechanisms responsible for cellular growth and differentiation. Nevertheless, other embryos such as those of amphibians are more suitable for studying the unfertilized egg and the very early stages of development immediately after fertilization. There are two obvious variables during embryonic development of the chick: on the one hand there is an increase in the amount of living tissue, and on the other, a proportional depletion in the amount of available food material. The chemical growth of the embryo expressed by the actual weight or increase in weight, plotted against time, yields a characteristic S-line. This is common of many other organisms at different phylogenetic levels, and indicates that the chick embryo grows more rapidly during the second half of its development. Taking into consideration the percentage of growth rate of wet weight of the chick embryo (see FIGURE l ) , there is a rapid fall initially from very high to low values. The genera1 opinion of embryologists is that the decrease in the specific rate of growth is due to the slowing down of the biosynthetic processes and of the mitotic index.' The embryo can be an advantageous system for studying the polyamine role in cellular metabolism, considering the relationship existing between these substances and cellular growth as has been shown in microorganism^,^^^ in cultured cells,: in animal and vegetable tissues '3 and in regenerating liver.s The chick embryo was chosen because in previous experiments spermine and spermidine could not be detected in the yolk of unincubated eggs, whereas the presence of both in the early stage of embryo development indicated an en novo synthesis. The presence of polyamines in embryonic tissues and in those in which we observe a higher protein synthesis, such as pancreas, liver, and prostate gland, led us to suspect a close relationship between these polycationic compounds and nucleic acid metabolism. The first observation concerns the parallel behavior of both polyamine and nucleic acid concentrations during the successive stages of chick embryo development. The maximum levels of polyamines correspond to the nucleic acid ones. It is interesting to note that by inhibiting the amino oxidase activities, the polyamine concentration increased rapidly followed by a parallel increase

G. Moruzzi

Papers

Polyamines and nucleic acid metabolism in the chick embryo