[A historical review and some comments on the nuclear transplantation in fish]

In this review article, a brief history and main results of the studies on the nuclear transplantation (cloning) in fish was introduced. Late Professor T. C. Tung (TONG Di-Zhou), a noted Chinese Experimental Embryologist and his research group at the Institute of Zoology, the Chinese Academy of Sciences (CAS) in Beijing, China initiated and established successful technology of nuclear transplantation in fish in 1963. During the past 36 years, most of the studies on fish cloning were performed mainly by Chinese groups except only one article was published by authors in former USSR (Gasaryan et al. 1979), and the other one was published by Japanese authors in Japan (Niwa et al. 1999). The primary goals of the studies of Tung's group were: (1) to study the inter-relationship between the nucleus and the cytoplasm in terms of the controlling effects determined by nucleus or cytoplasm or both during the ontogenesis, cell differentiation and phenotypic expression in a developing animal; and (2) to produce fish clones of commercial importance for agricultural purposes. The most successful results that have been obtained by Tung's group in collaboration with the investigators at various fisheries institutions in China were the production of nucleocytoplasmic adult hybrid fish between different varieties, species, genera and subfamilies that produced viable offspring. Furthermore, these nucleocytoplasmic fish hybrid revealed that while most phenotypic characteristics are controlled by the nucleus, a few are controlled by the cytoplasm or by both. In addition, the resulting nucleocytoplasmic fish hybrids also showed some better characteristics of economic importance such as faster growth rate, increasing of protein content and reducing of fat content in muscle, etc. So far, no such kinds of evidences are available either in amphibian or in mammals. Another most important result obtained by other Chinese groups showed that the uncultured or cultured adult somatic cell in fish which can support the nuclear transplanted eggs developing into adults. They were: (1) a 17 month old gold-fish obtained by transplanting an adult erythrocytes into an enucleated egg (WU et al. 1982); (2) a subcultured kidney cell nucleus of Crucian carp (Carassius auratus) can support the transplanted enucleated egg of same species developing into a three years old adult with female sexual characteristics (CHEN et al. 1986) and (3) a cultured liver cell nucleus from grass carp (Ctenopharyngoden idellus) can support a nuclear transplanted unfertilized egg of the same species developing into an adult fish at least of one year old when that paper was published. Some discussions and comments for evaluating the results obtained from previous studies and suggestions for further investigations in this research field are also provided. More detailed information could be found in the book--"Cloning in Fish-nucleocytoplasmic Hybrids" which was written by Shaoyi Yan in English and published by International Union of Biological Sciences and Educational and Cultural Press Ltd. Hong Kong in 1998.