[Chromosomal radiosensitivity as associated with chromatin diminution in cyclops (Crustacea, Copepoda)].

Chromosomal radiosensitivity inferred from the yield of chromosome aberrations (CAs) was for the first time studied in Cyclops (Crustacea, Copepoda) before and after chromatin diminution (CD). A comparison was made for C. kolensis, in which CD denudes somatic embryo cells of the greatest (94%) DNA amount known for multicellular organisms, and C. insignis, which lacks CD. The two species have similar genome sizes, 4.6 and 4.3 pg. respectively. Radiosensitivity of C. kolensis chromosomes proved to be extremely high during prediminution cleavage divisions. This was attributed to membrane damage in granules that contain enzymes (topoisomerases) normally involved in cleavage and ligation of chromosomal DNA during CD.