Mentsük a menthetőt – új lehetőségek baromfifélék in vitro génmegőrzésé nek terén Irodalmi áttekintés

Abstract

SUMMARY The authors present a comprehensive review about the significance of the main tenance of genetic diversity, the possibilities of ex situ/in vitro gene conservation in poultry species. There is an introduction of the various ways of the preserva tion of genetic material, the results achieved so far at international level, as well as the present developments in the Centre for Farm Animal Gene Conservation, in Hungary. There is a detailed presentation of the difficulties and the results of sperm cryo preservation of the indigenous poultry breeds, which is the most effective and practical way for the long term storage of poultry genes at the present time, although in the case of spermatozoa only the haploid male genome can be preserved. However, by 6-8 re-crossing using frozen/thawed sperm the whole genome can be retained. The fertility rates obtained with frozen thawed semen are variable depending on the species and the employed protocols. According to the latest results chicken and gander spermatozoa seem to be more resistant to freezing damage than the spermatozoa of other domestic birds. Since in the case of avian species neither the oocytes nor the embryos can be frozen due to the high content of non-freezable yolk, the long term conservation of the early embryonic cells (BCs and PGCs) is the only way to preserve the whole genetic material. In these methods the collection of cells from the donor eggs, their freezing/thawing and the injection of them into the germinal discs or the dorsal aorta of the fertile recipient eggs mean big challenges for the research ers. Presently, by the manipulation with early embryonic cells the rate of donor derived progenies is highly variable. For long term maintenance of the female genome the only possibility is the dissection, freezing/thawing and grafting of the ovary of donor day old chick ens into the recipient ones with the same age. This method is the newest and most complicated, however, really promising way of the avian gene conserva tion. Nowadays, the applications of all the mentioned methods in the gene conservation programs are achievable.