Modifications of lampbrush chromosome structure of the European domestic goose Anser anser

Abstract. Lampbrush chromosomes (LBCs) represent a new model in avian cytogenetics and are increasingly more often used in poultry chromosome analyses. Additionally, lampbrush chromosomes are considered as model structures in the study of transcription regulation. Changes in transcription activity are reflected as modifications of LBC morphological structure and associated with physiological processes in the organism. The aim of the present study was to compare transcriptional activity of the first five lampbrush macrochromosomes and ZW sex lampbrush bivalents sampled from the oocytes of geese prior to and after the reproductive period. The respective bivalents sampled before and after reproduction have similar sizes but differ in morphological structure. Side loops of lampbrush chromosomes are sites of transcription activity. The activity varies according to the loop size. As the loops become more prominent, the activity grows and vice versa. Lampbrush chromosomes sampled after reproduction have smaller side loops. On the other hand, inactive chromomeres become prominent in the chromosomes. Marker loops are the last structures to be degraded after the end of reproduction. Consequently, they are used for identifying particular bivalents at different stages of cellular transcriptional activity.