Four new experimental methods developed: 1) DNA amplification by the "lone-linker" method and RARGIP (random access retrieval of genetic information through PCR) method to greatly streamline the entire process from RNA to cDNA; 2) an equalized cDNA library for making a complete mRNA catalogue from a given organism; 3) an in-gel competitive reassociation (IGCR) method for recognizing subtle differences in DNA structure in cell types from various tissues and organs; and 4) the establishment of immortalized cell lines which maintain normal characteristics, the division of which can be controlled.
Germ plasm in Xenopus: Concerning a study of germ-cell differentiation, the germ plasm from Xenopus eggs was isolated by differential centrifugation and made specific monoclonal antibodies against the germ plasm, some of which react to both germinal granules and mitochondria.
Germ cell specific-mRNA encoding a regulator gene in mice: cDNA was cloned with a zinc-finger motif, which is specifically expressed in primordial germ cells and gonia in mice, using the lone-linker and RARGIP method. This function was examined.
Equalized cDNA library of developing mice: According to the previously reported principle, an equalized cDNA library was made using materials from fertilized eggs to the prenatal embryos in mice. A line-up filter of the equalized cDNA was also provided.
Changes in the primary DNA structure in rat brain: The testing of several alternative model systems to improve the sensitivity of the IGCR method and cloning differences in DNA structure between the brain and liver in the rat is being carried out.
Establishment of immortalized cell lines with normal characteristics: Transgenic mice with temperature-sensitive oncogenes were made, and several tissues from these mice were transferred to in vitro culture systems. Immortalized cell lines which maintained normal characteristics were successfully established.
Evolution: A new evolution theory has been proposed: the "Disparity theory of evolution".