CHROMOSOME ELIMINATION IN 3 BALTIC, SOUTH-PACIFIC AND NORTHEAST PACIFIC HAGFISH SPECIES

We have confirmed that chromosome elimination occurs in the cells of M yxine glutinosa, collected from the Baltic Sea off Sweden, Eptatretus cirrhatus from the south Pacific Ocean off the east coast of New Zeala nd, and E. stoutii from the north-east Pacific Ocean off Canada, simil ar to cells of four Japanese hagfish species. In M. Glutinosa, E. cirr hatus type A, E. cirrhatus type B and E. stoutii, the differences in c hromosome number between spermatogonia (44, 72, 80 and 48) and somatic cells (28, 34, 34 and 34) were 16, 38, 46 and 14 respectively. The am ount of DNA eliminated from presumptive somatic cells averaged 43.5%, 48.7%, 54.6% and 52.8% respectively. Euchromatic chromosomes and/or pa rts of chromosomes in addition to heterochromatic chromosomes were cle arly eliminated in E. cirrhatus and E. stoutii. Adding our previous ob servations of four Japanese hagfish species, chromosome elimination oc curs in all seven of the hagfish species. These results suggest that t his phenomenon, chromosome elimination, generally occurs in the order Myxinida. In addition, B chromosomes were observed in the germ cells o f E. cirrhatus and E. stoutii, similar to the cells of E. okinoseanus, E. burgeri and Paramyxine atami (E. atami). This fact suggests that B -chromosomes might exist generally in the family Eptatretidae.