1. Laboratory of Developmental Genetics; Institute of Experimental Endocrinology; Biomedical Centre; Slovak Academy of Sciences; Dúbravská cesta 9 84505 Bratislava Slovakia
2. Department of Genetics; Comenius University; Mlynská dolina B-1 84215 Bratislava Slovakia
3. Department of Medical Biochemistry; Jessenius Faculty of Medicine; Comenius University; Malá Hora 4 03601 Martin Slovakia
4. Faculty of Agrobiology; Food and Natural Resources; Czech Agricultural University; Kamýcká 129 16521 Prague 6 Czech Republic
5. Institute of Cellular Biology and Pathology; 1st Faculty of Medicine; Charles University in Prague; Albertov 4 12800 Prague Czech Republic
6. Department of Biology; University of Nebraska at Omaha; 6001 Dodge Street Omaha Nebraska 68182-0040 USA