1. Institute
of Animal Reproduction and Food Research, Polish Academy of Sciences, Tuwima 10, 10-748 Olsztyn, Poland
2. Institute
of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego
5A, 02-106 Warsaw, Poland
3. Department
of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium