| Dictyostelium discoideum is a lower eukaryotic protozoan. It is in the root of the Phylogenetic tree. It has a alternative development process in the life cycle. Dictyostelium discoideum bred by bipartition in the good growth environment and the single cells assembled to multi-cellular aggregate in the harsh condition. A pathway consists of aggregation, mound, slug, and fruiting body phases during the multi-cellular development of Dictyostelium discoideum. It is not only a change happened in cell morphology, but also a series of signaling molecules involved in the regulation of development process. At first, Dictyostelium discoideum release chemical signal of cAMP in the harsh environment so that cells can crawl to the source of cAMP, and under the influence of gp80 and DdCAD-1, cells gradually come together. Then under the influence of gp150 and DIF-1, cells start differentiation. In this process, the multi-cells differentiate into prestalk and prespore, prestalk have a further differentiation later. At last, prespore developed into mature spore cells and prestalk developed into mature stalk. Because Dictyostelium discoideum has a simple structure, the whole development process is only 24 hours, and it involved a series of signaling molecules in the regulation, Dictyostelium discoideum is a good material for study of signal transduction, cell development and cell movement. It is reported that gp150 regulated cell-cell adhesion by heterophilic interactions. The mutant type strain AK127, as a result of absence of gp150, can't complete multi-cellular development and the process is arrested at the loose aggregate phase, so gp150 is very important in the development of Dictyostelium discoideum. When we study the function of gp150 during the development of multi-cells, we founded another gene-- allantoicase gene. Therefore we speculate that allantoicase has some relationship with gp150. Allantoicase is an important enzyme in the metabolization of purines. It catalyzes the conversion of allantoicase into glyoxylate and Urea. And the latter was resolved into ammonia and CO2. Quit a long time ago, ammonia was proposed to be an important signaling molecule, which regulate the development of Dictysotelium discoideum. In order to know how the allantoicase work in the development of Dictyostelium discoideum, location and expression of allanoicase were observed in the wild type KAx-3 and mutant type AK 127 cells during development by immunofluorescent technique and Western blot respectively. The results showed that abundant of allanoicase existed near the cytomembrane at the aggregation stage, so we speculate that it may take part in the regulation at the aggregation stage of Dictysotelium discoideum. At the mound stage, the fluorescence of allanoicase in the peripheral cells of mound was stronger than other place cells, and the peripheral cells of mound will be the stalk cells. When they developed into slug stage, more allanoicase existed in prestalk cells than that in prespore cells. The fluorescence of allanoicase expressed strongly at the junction of prespore area and prestalk area at the fruiting body stage, these cells would differentiate into prestalk B cells. These data indicated that there may be some relationships between the expression of allanoicase and cell-type differentiation during Dictysotelium discoideum development.The results of Western blot showed that the expression of allanoicase increased gradually in the development of KAx-3 cells. The expression amount of allanoicase was maximum when the cells developed nearly 18 hours, then it declined sharply after 18 hours. But the expression of allanoicase in AK127 cells which gene of gp150 protein was knocked out was always at a low level. It shows that the expression of allanoicase would be affected in the absence of gp150. The results indicate that the expression of allanoicase has some relationships with the developmental time of the cells, and is also associated with the expression of gp150 gene.
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