Analysis of Morphogenesis and Differentiation of Dictyostellium by restriction enzyme mediated insertion (REMI)

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Takeuchi, I.organized Dictyostelium cDNA project with several members of this research group and started in the last autumn. He also found that prestalk and prespore cells sucked into a capillary tube do not differentiate at a constant propotion, as in ordinary slugs.Molecular mechanism of morphogenesis Suto, K.analyzed a REMI mutant which dose not develop after aggregation, and found that the mutated genes is a homologue of SSN6 gene of yeast. Ochiai, H.prepared rabbit polyclonal antibody raised against the membrance fraction isolated from Polysphondylium cells transformed with an antisence RNA-expressing plasmid to reduce cell-adhesion protein. As the antibody efficiently inhibits Polysphondylium cell-adhesion, it will be a good tool to analyze the mechanism in the formation of multeicellular structure of the organism. Molecular machanism of differentiation To investigate a switch mechanism from growth to differentiation, Maeda, Y.cloned two genes (Quit2,3) which are expressed around the critical point (PS point) of the cell cycle. He found that Quit2 encodes a new calcium-binding protein and Quit3 has a sequence coding for the complementary strand of annexin Vll gene. Oohata, A.isolated a factor induction of prespore differentiation in vitro. Maeda, M.revealed that the gene is essential for aggregation and that hetero-trimeric G proteins are not required for this regulation. Tanaka, Y.established the techniques for an insertional mutagenesis with Polysphondylium cells by the use of REMI method. Ishida, S.isolated 'sporogenous mutant', in which even single cells differentiate into spores and tag mutants which stop at the 'tight aggregate' stage. Urushihara, H.analyzed two sorts of REMI mutants (TMC1 and MCF1). TMC1 was normal for sexual cell fusion, but was unusual for chemotaxis. MCF1 had a defect in sexual cell fusion.